0000950170-24-043516 | 20-F | XBRL Viewer

Year ended December 31,

Financial assets at fair value through other
comprehensive income

Foreign unlisted stocks

Expenses by nature

12 Months Ended

Dec. 31, 2023

Analysis of income and expense [abstract]

29.

Expenses by nature


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Raw materials and supplies used	5,518,145	4,512,527	3,991,490
Employee benefit expenses	6,757,888	6,466,303	5,836,068
Depreciation expenses	4,634,112	4,751,902	4,779,333
Others	5,053,088	4,699,586	4,926,828
	21,963,233	20,430,318	19,533,719

Pensions

12 Months Ended

Dec. 31, 2023

Disclosure of defined benefit plans [abstract]

Pensions

18.

Pensions

Defined Benefit Plans

The Company has a defined benefit pension plan in accordance with the Labor Standards Act, covering all regular employees’ service years prior to the enforcement of the Labor Pension Act on July 1, 2005 and service years thereafter of employees who chose to continue to be subject to the pension mechanism under the Labor Standards Act. Under the defined benefit pension plan, two units are accrued for each year of service for the first 15 years and one unit for each additional year thereafter, subject to a maximum of 45 units. Pension benefits are based on the number of units accrued and the average monthly salaries and wages of the last 6 months prior to retirement. The Company contributes monthly an amount equal to 2% of the employees’ monthly salaries and wages to the pension fund deposited with the Bank of Taiwan, the trustee, under the name of the independent pension fund committee. Also, the Company would assess the balance in the aforementioned labor pension reserve account by the end of every year. If the account balance is insufficient to pay the pension calculated by the aforementioned method, to the employees expected to be qualified for retirement next year, the Company will make contributions to cover the deficit by March of following year.

(a)

The amounts recognized in the statements of financial position are as follows:


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Present value of defined benefit obligations	(759,548)	(744,191)
Fair value of plan assets	500,333	516,854
Net defined benefit liability	(259,215)	(227,337)

(b)

Movements in net defined benefit liability are as follows:


	2021
	Present value of defined benefit obligations	Fair value of plan assets	Net defined benefit liability
	NT$000	NT$000	NT$000
January 1	(943,391)	431,740	(511,651)
Current services cost	(237)	—	(237)
Interest (expense) income	(4,629)	2,137	(2,492)
	(948,257)	433,877	(514,380)
Remeasurements:
Return on plan assets (excluding amounts included in interest income or expense)	—	5,613	5,613
Impact on changes in demographic assumptions	(20,022)	—	(20,022)
Financial assumption movement effect	23,757	—	23,757
Experience adjustments	(24,347)	—	(24,347)
	(20,612)	5,613	(14,999)
Pension fund contribution	—	26,091	26,091
Paid pension	9,192	(9,192)	—
December 31	(959,677)	456,389	(503,288)


	2022
	Present value of defined benefit obligations	Fair value of plan assets	Net defined benefit liability
	NT$000	NT$000	NT$000
January 1	(959,677)	456,389	(503,288)
Current services cost	(257)	—	(257)
Interest (expense) income	(6,589)	3,161	(3,428)
	(966,523)	459,550	(506,973)
Remeasurements:
Return on plan assets (excluding amounts included in interest income or expense)	—	34,550	34,550
Financial assumption movement effect	73,218	—	73,218
Experience adjustments	114,466	—	114,466
	187,684	34,550	222,234
Pension fund contribution	—	25,524	25,524
Paid pension	19,291	(19,291)	—
December 31	(759,548)	500,333	(259,215)


	2023
	Present value of defined benefit obligations	Fair value of plan assets	Net defined benefit liability
	NT$000	NT$000	NT$000
January 1	(759,548)	500,333	(259,215)
Current services cost	(133)	—	(133)
Interest (expense) income	(11,150)	7,441	(3,709)
	(770,831)	507,774	(263,057)
Remeasurements:
Return on plan assets (excluding amounts included in interest income or expense)	—	3,187	3,187
Impact on changes in demographic assumptions	14,216	—	14,216
Financial assumption movement effect	(7,103)	—	(7,103)
Experience adjustments	399	—	399
	7,512	3,187	10,699
Pension fund contribution	—	25,021	25,021
Paid pension	19,128	(19,128)	—
December 31	(744,191)	516,854	(227,337)

(c)

The Bank of Taiwan was commissioned to manage the fund of the Company’s defined benefit pension plan in accordance with the fund’s annual investment and utilization plan and the Regulations for Revenues, Expenditures, Safeguard and Utilization of the Labor Retirement Fund (Article 6: The scope of utilization for the fund includes deposit in domestic or foreign financial institutions, investment in domestic or foreign listed, over-the-counter, or private placement equity securities, investment in domestic or foreign real estate securitization products, etc.). With regard to the utilization of the fund, its minimum earnings in the annual distributions on the final financial statements shall be no less than the earnings attainable from the amounts accrued from two-year time deposits with the interest rates offered by local banks. If the earnings are less than aforementioned rates, government shall make payment for the deficit after being authorized by the authority. The Company has no right to participate in managing and operating

that fund and hence the Company is unable to disclose the classification of the fair value of plan asset in accordance with IAS 19, “Employee Benefits” paragraph 142. The composition of fair value of plan assets as of December 31, 2022 and 2023 is given in the Annual Labor Retirement Fund Utilization Report announced by the government.

(d)

The principal actuarial assumptions used were as follows:


	Year ended December 31,
	2022	2023
Discount rate	1.50%	1.40%
Future salary increase	3.50%	3.50%

Assumptions regarding future mortality are set based on actuarial advice in accordance with published statistics and experience in each territory.

The present value of defined benefit obligations is affected by the change in actuarial assumption. The analysis was as follows:


	Discount rate		Future salary increase
	Increase 0.25%	Decrease 0.25%	Increase 0.25%	Decrease 0.25%
	NT$000	NT$000	NT$000	NT$000
December 31, 2022
Effect on present value of defined benefit obligations	(20,992)	21,860	21,385	(20,651)
December 31, 2023
Effect on present value of defined benefit obligations	(17,562)	18,228	17,817	(17,262)

The sensitivity analysis above is based on a change in an assumption while holding all other assumptions constant. In practice, changes in some of the assumptions may be correlated. The method of sensitivity analysis and the method of calculating net defined benefit liability in the statements of financial position are the same.

The methods and types of assumptions used in preparing the sensitivity analysis remain unchanged from previous period.

(e)

Expected contributions to the defined benefit pension plans of the Company for the year ending December 31, 2024 amounts to NT$24,000 thousand.

(f)

As of December 31, 2023, the weighted average duration of that retirement plan is 9.7 years. The analysis of timing of the future pension payment was as follows:


		December 31, 2023
		NT$000
Within 1 year		69,288
1-2 years		42,487
2-5 years		115,279
5-10 years		181,850
		408,904

Defined Contribution Plans

(a)

Effective from July 1, 2005, the Company established a defined contribution pension plan (“New Plan”) under the Labor Pension Act, covering all regular employees with ROC nationality. Under the New Plan, the Company contributes monthly an amount based on 6% of the employees’ monthly salaries and wages to the employees’ individual pension accounts at the Bureau of Labor Insurance. The benefits accrued are paid monthly or in lump sum upon termination of employment. The pension costs under defined contribution pension plans of the Company for the years ended December 31, 2021, 2022 and 2023 were NT$197,076 thousand, NT$201,606 thousand and NT$190,913 thousand, respectively.

(b)

According to the defined contribution pension plan stipulated by PRC, ChipMOS Shanghai contributes monthly on amount based on a certain percentage of the local employees’ monthly salaries and wages. The contribution percentage was both 16% for the years ended December 31, 2021, 2022 and 2023. The pension of each employee is managed by the government and ChipMOS Shanghai has no further obligations except the monthly contribution. The pension costs under defined contribution pension plan of ChipMOS Shanghai for the years ended December 31, 2021, 2022 and 2023 were NT$209 thousand, NT$380 thousand and NT$604 thousand, respectively.

Pensions - Principal Actuarial Assumptions Used and Sensitivity Analysis of Present Value of Defined Benefit Obligation Effected by Changes of Principal Actuarial Assumptions (Detail)	Dec. 31, 2023	Dec. 31, 2022
Disclosure of sensitivity analysis for actuarial assumptions [abstract]
Discount rate	1.40%	1.50%
Future salary increases	3.50%	3.50%

Related Party Transactions - Key Management Personnel Compensation (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of transactions between related parties [abstract]
Salaries and other short-term employee benefits	$ 176,702	$ 211,620	$ 243,405
Post-employment compensation	2,158	2,197	2,156
Total key management personnel compensation	$ 178,860	$ 213,817	$ 245,561

Significant events after the reporting periods	12 Months Ended
Significant events after the reporting periods	Dec. 31, 2023
Significant events after the reporting period [Abstract]
Significant events after the reporting periods	39. Significant events after the reporting period On December 21, 2023, the Company’s Board of Directors approved its subsidiary ChipMOS BVI to sell the 45.0242% owned equity investment accounted for using equity method in Unimos Shanghai. The equity transfer is expected to be completed in the first half of 2024.

Other equity interest

12 Months Ended

Dec. 31, 2022

Disclosure of reserves within equity [abstract]

Other equity interest

22.

Other equity interest


	2021
	Financial statements translation differences of foreign operations	Unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income	Total
	NT$000	NT$000	NT$000
January 1	(61,330)	194,716	133,386
Currency translation differences
- The Company	(24,695)	—	(24,695)
Evaluation adjustment
- The Company	—	122,514	122,514
- Associates	—	21,094	21,094
Evaluation adjustment related tax
- The Company	—	(30,459)	(30,459)
December 31	(86,025)	307,865	221,840


	2022
	Financial statements translation differences of foreign operations	Unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income	Total
	NT$000	NT$000	NT$000
January 1	(86,025)	307,865	221,840
Currency translation differences
- The Company	68,656	—	68,656
Evaluation adjustment
- The Company	—	(46,419)	(46,419)
- Associates	—	(28,353)	(28,353)
Evaluation adjustment related tax
- The Company	—	12,559	12,559
December 31	(17,369)	245,652	228,283


	2023
	Financial statements translation differences of foreign operations	Unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income	Equity directly related to non-current assets held for sale	Total
	NT$000	NT$000	NT$000	NT$000
January 1	(17,369)	245,652	—	228,283
Currency translation differences
- The Company	16,713	—	—	16,713
- Non-current assets held for sale	—	—	(43,094)	(43,094)
Evaluation adjustment
- The Company	—	(217,785)	—	(217,785)
- Associates	—	12,605	—	12,605
Evaluation adjustment related tax
- The Company	—	51,638	—	51,638
December 31	(656)	92,110	(43,094)	48,360

Expenses by nature - Summary of Expenses by nature (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Analysis of income and expense [abstract]
Raw materials and supplies used	$ 3,991,490	$ 4,512,527	$ 5,518,145
Employee benefit expenses	5,836,068	6,466,303	6,757,888
Depreciation expenses	4,779,333	4,751,902	4,634,112
Others	4,926,828	4,699,586	5,053,088
Total operating costs and expenses	$ 19,533,719	$ 20,430,318	$ 21,963,233

Pensions - Sensitivity Analysis of Present Value of Defined Benefit Obligations Effected by Changes of Significant Actuarial Assumptions (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Actuarial assumption of discount rates [member]
Disclosure of sensitivity analysis for actuarial assumptions [Line Items]
Percentage increase in assumption	0.25%	0.25%
Effect on present value of defined benefit obligations due to increase in assumption	$ (17,562)	$ (20,992)
Percentage decrease in assumption	0.25%	0.25%
Effect on present value of defined benefit obligations due to decrease in assumption	$ 18,228	$ 21,860
Actuarial assumption of expected rates of salary increases [member]
Disclosure of sensitivity analysis for actuarial assumptions [Line Items]
Percentage increase in assumption	0.25%	0.25%
Effect on present value of defined benefit obligations due to increase in assumption	$ 17,817	$ 21,385
Percentage decrease in assumption	0.25%	0.25%
Effect on present value of defined benefit obligations due to decrease in assumption	$ (17,262)	$ (20,651)

Other income (expenses), net (Tables)

12 Months Ended

Dec. 31, 2023

Other income expenses net [abstract]

Summary of Other Income (Expenses), Net


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Gain on disposal of property, plant and equipment, net	33,935	74,548	18,431
Gain on disposal of scrapped materials	52,254	35,381	44,662
Gain on disposal of items purchased on behalf of others	21,945	19,107	12,729
Gain from lease modifications	891	139	—
Impairment loss on property, plant and equipment	(4,843)	(12,721)	(9,236)
Others	21,405	13,479	19,357
	125,587	129,933	85,943

Corporate and group information	12 Months Ended
Corporate and group information	Dec. 31, 2023
Disclosure of corporate and group information [abstract]
Corporate and group information	1. Corporate and group information ChipMOS TECHNOLOGIES INC. (the “Company” or “ChipMOS Taiwan”) was incorporated in the Republic of China (“ROC”) on July 28, 1997. The Company and its subsidiaries (collectively referred herein as the “Group”) are primarily engaged in the research, development, manufacturing and sale of high-integration and high-precision integrated circuits and related assembly and testing services. On April 11, 2014, the Company’s shares were listed on the Taiwan Stock Exchange (“TWSE”). On November 1, 2016, the Company’s American Depositary Shares (“ADSs”) were listed on the NASDAQ Global Select Market and traded under the ticker symbol “IMOS”.

Segment Information - Schedule of Geographical Information (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Non-current assets [abstract]
Total non-current assets	$ 20,367,567	$ 21,680,847
ROC [member]
Non-current assets [abstract]
Total non-current assets	20,360,166	21,677,980
PRC [member]
Non-current assets [abstract]
Total non-current assets	1,279	2,291
Others [Member]
Non-current assets [abstract]
Total non-current assets	$ 6,122	$ 576

The authorization of the consolidated financial statements	12 Months Ended
	Dec. 31, 2023
Disclosure of authorization of the consolidated financial statements [abstract]
The authorization of the consolidated financial statements	2. The authorization of the consolidated financial statements The accompanying consolidated financial statements were authorized for issuance by the Board of Directors on April 11, 2024.

Significant contingent liabilities and unrecognized contract commitments - Capital Expenditures that are Contracted for, but not Provided for (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Disclosure of detailed information about property, plant and equipment [abstract]
Property plant and equipment, Contracted capital expenditures	$ 1,940,740	$ 1,703,841

Revenue (Tables)

12 Months Ended

Dec. 31, 2023

Receivables from contracts with customers [abstract]

Summary of Revenue from Contracts with Customers


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Revenue from contracts with customers	27,400,035	23,517,064	21,356,228

Summary of Contract Assets

The Group has recognized the following contract assets in relation to revenue from contracts with customers:


	January 1, 2022	December 31, 2022	December 31, 2023
	NT$000	NT$000	NT$000
Contract assets	400,255	381,358	383,883

Leasing arrangements - leasee - Summary of profit and loss accounts relating to lease contracts (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Items affecting profit or loss
Interest expense on lease liabilities	$ 18,757	$ 14,556	$ 15,245
Expense on short-term lease contracts	$ 55,944	$ 95,213	$ 143,791

Financial statements schedule: valuation and qualifying accounts

12 Months Ended

Dec. 31, 2023

SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]

Financial statements schedule: valuation and qualifying accounts

43.

Financial statements schedule: valuation and qualifying accounts


	January 1	Additions charged to expense or deduction of revenue	Deduction / Write-offs / Reversal	December 31
	NT$000	NT$000	NT$000	NT$000
Year 2021
Allowance for impairment of property, plant and equipment	182,002	4,843	(3,666)	183,179
Allowance for impairment of obsolescence and decline in market value of inventories	79,815	41,771	—	121,586
Provision for deficiency compensation	3,463	11,898	(11,080)	4,281
Sales for allowance	9,864	34,744	(34,759)	9,849
Year 2022
Allowance for impairment of property, plant and equipment	183,179	12,721	(1,433)	194,467
Allowance for impairment of obsolescence and decline in market value of inventories	121,586	—	(15,956)	105,630
Provision for deficiency compensation	4,281	79,827	(57,465)	26,643
Sales for allowance	9,849	94,641	(67,367)	37,123
Year 2023
Allowance for impairment of property, plant and equipment	194,467	9,236	—	203,703
Allowance for impairment of obsolescence and decline in market value of inventories	105,630	80,633	—	186,263
Provision for deficiency compensation	26,643	21,495	(14,574)	33,564
Sales for allowance	37,123	112,488	(111,944)	37,667

For movements in loss allowance for contract assets, accounts receivable, and other receivables, please refer to Note 41 a).

Translation into U.S. Dollar Amounts - Additional Information (Detail)	Dec. 31, 2023
Foreign exchange rates [abstract]
Foreign exchange rate from New Taiwan dollars to U.S. dollars at the noon buying rate in the City of New York for cable transfers as certified for customs purposes by the Federal Reserve Bank of New York	30.62

Financial statements schedule: valuation and qualifying accounts (Tables)

12 Months Ended

Dec. 31, 2023

SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]

Disclosure Of Details Of Valuation And Qualifying Accounts

43.

Financial statements schedule: valuation and qualifying accounts


	January 1	Additions charged to expense or deduction of revenue	Deduction / Write-offs / Reversal	December 31
	NT$000	NT$000	NT$000	NT$000
Year 2021
Allowance for impairment of property, plant and equipment	182,002	4,843	(3,666)	183,179
Allowance for impairment of obsolescence and decline in market value of inventories	79,815	41,771	—	121,586
Provision for deficiency compensation	3,463	11,898	(11,080)	4,281
Sales for allowance	9,864	34,744	(34,759)	9,849
Year 2022
Allowance for impairment of property, plant and equipment	183,179	12,721	(1,433)	194,467
Allowance for impairment of obsolescence and decline in market value of inventories	121,586	—	(15,956)	105,630
Provision for deficiency compensation	4,281	79,827	(57,465)	26,643
Sales for allowance	9,849	94,641	(67,367)	37,123
Year 2023
Allowance for impairment of property, plant and equipment	194,467	9,236	—	203,703
Allowance for impairment of obsolescence and decline in market value of inventories	105,630	80,633	—	186,263
Provision for deficiency compensation	26,643	21,495	(14,574)	33,564
Sales for allowance	37,123	112,488	(111,944)	37,667

For movements in loss allowance for contract assets, accounts receivable, and other receivables, please refer to Note 41 a).

Consolidated Statements of Cash Flows $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Cash flows from operating activities
Profit before income tax	$ 2,268,226	$ 74,077	$ 4,027,872	$ 6,035,585
Adjustments to reconcile profit (loss)
Depreciation expenses	4,779,333	156,085	4,751,902	4,634,112
Expected credit losses (gains)	(302)	(10)	897	299
Interest expense	265,957	8,686	142,439	120,998
Interest income	(193,189)	(6,309)	(57,199)	(9,980)
Dividend income	(6,592)	(215)	(9,816)	(4,690)
Share of profit of associates and joint ventures accounted for using equity method	(219,891)	(7,182)	(453,715)	(625,733)
(Gain) loss on valuation of financial assets at fair value through profit or loss	(39,254)	(1,282)	69,404	(15,262)
Gain on disposal of property, plant and equipment, net	(18,431)	(602)	(74,548)	(33,935)
Gain from lease modifications			(139)	(891)
Impairment loss on property, plant and equipment	9,236	302	12,721	4,843
Deferred revenue	(20,839)	(681)	(17,859)	(12,389)
Financial assets at fair value through profit or loss	124,743	4,074	162,332	(290,637)
Current contract assets	(2,470)	(81)	18,788	(11,242)
Accounts and notes receivable	(944,603)	(30,849)	1,962,959	(980,816)
Other receivables	48,736	1,592	15,849	(46,089)
Inventories	641,761	20,959	(3,232)	(1,105,102)
Prepayments	3,104	101	37,748	(67,401)
Other non-current assets				6,915
Accounts and notes payable	224,469	7,331	(451,480)	42,694
Other payables	(90,786)	(2,965)	(161,212)	471,766
Current provisions	6,921	226	22,362	818
Current refund liabilities	544	18	27,274	(15)
Other current liabilities	1,293	42	8,097	(6,838)
Net defined benefit liability, non-current	(21,179)	(692)	(21,839)	(23,362)
Cash generated from operations	6,816,787	222,625	10,009,605	8,083,648
Interest received	194,136	6,340	42,170	10,344
Dividend received	10,327	337	26,416	17,140
Interest paid	(227,488)	(7,429)	(107,210)	(99,857)
Income tax paid	(186,280)	(6,084)	(1,354,548)	(691,566)
Net cash generated from operating activities	6,607,482	215,789	8,616,433	7,319,709
Cash flows from investing activities
Acquisition of financial assets at amortized cost	(72,201)	(2,358)	(133,182)
Proceeds from repayments of financial assets at amortized cost	130,220	4,253	69,022	188,023
Acquisition of financial assets at fair value through other comprehensive income	(12,500)	(408)
Proceeds from disposal of financial assets at fair value through profit or loss				9,427
Acquisition of property, plant and equipment	(3,073,881)	(100,389)	(4,699,369)	(5,881,506)
Proceeds from disposal of property, plant and equipment	83,679	2,733	77,339	120,586
(Increase) decrease in refundable deposits	1,064	35	(493)	(92)
Increase in other non-current assets	(160,703)	(5,248)	(400,569)	(501,177)
Increase in long-term deferred revenue	14,145	462	25,328	49,349
Net cash used in investing activities	(3,090,177)	(100,920)	(5,061,924)	(6,015,390)
Cash flows from financing activities
Proceeds from short-term bank loans	1,273,873	41,603	348,006	2,195,726
Payments on short-term bank loans	(1,273,873)	(41,603)	(1,079,757)	(1,463,975)
Payment on lease liabilities	(293,383)	(9,581)	(237,869)	(289,668)
Proceeds from long-term bank loans	2,430,224	79,367	4,567,672	4,908,782
Payments on long-term bank loans	(1,522,918)	(49,736)	(54,000)	(3,256,450)
Decrease in guarantee deposits	(365)	(12)	(25)	(45)
Cash dividend paid	(1,672,652)	(54,626)	(3,127,133)	(1,599,928)
Net cash generated from (used in) financing activities	(1,059,094)	(34,588)	416,894	494,442
Effect of foreign exchange rate changes	(780)	(25)	19,025	(6,236)
Net increase in cash and cash equivalents	2,457,431	80,256	3,990,428	1,792,525
Cash and cash equivalents at beginning of year	9,896,604	323,207	5,906,176	4,113,651
Cash and cash equivalents at end of year	$ 12,354,035	$ 403,463	$ 9,896,604	$ 5,906,176

Financial Risk Management And Fair Values Of Financial Instruments - Summary of Effect of Profit or Loss or of Other Comprehensive Income from Financial Assets Categorized (Detail) - Financial instruments at fair value through other comprehensive income [member] - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Favorable Changes	$ 2,231	$ 6,866
Unfavorable Changes In Fair Value	2,152	6,922
Discount for lack of marketability [member]
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Favorable Changes	1,453	3,990
Unfavorable Changes In Fair Value	1,413	4,039
Foreign unlisted stocks [member] \| Price to book ratio multiple [member]
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Favorable Changes	30
Unfavorable Changes In Fair Value	30
Foreign unlisted stocks [member] \| Enter prise value EBITDA multiple [member]
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Favorable Changes	748	2,876
Unfavorable Changes In Fair Value	$ 709	$ 2,883

Capital surplus

12 Months Ended

Dec. 31, 2023

Capital surplus [Abstract]

Capital surplus

20.

Capital surplus

Pursuant to the ROC Company Act, any capital surplus arising from paid-in capital in excess of par value on issuance of ordinary shares and donations can be used to cover accumulated deficits or to issue new shares or cash to shareholders in proportion to their share ownership, provided that the Company has no accumulated deficits. Furthermore, the ROC Securities and Exchange Act requires that the amount of capital surplus to be capitalized mentioned above may not exceed 10% of the paid-in capital each year. The capital surplus may not be used to cover accumulated deficits unless the surplus reserve is insufficient.


	2021
	Share premium	Others	Total
	NT$000	NT$000	NT$000
January 1	6,043,483	7,304	6,050,787
Changes in associates accounted for using equity method	—	4,834	4,834
December 31	6,043,483	12,138	6,055,621


	2022
	Share premium	Others	Total
	NT$000	NT$000	NT$000
January 1	6,043,483	12,138	6,055,621
Changes in associates accounted for using equity method	—	152	152
December 31	6,043,483	12,290	6,055,773


	2023
	Share premium	Others	Total
	NT$000	NT$000	NT$000
January 1	6,043,483	12,290	6,055,773
December 31	6,043,483	12,290	6,055,773

Cash and cash equivalents (Tables)

12 Months Ended

Dec. 31, 2023

Cash and cash equivalents [abstract]

Summary of Cash and Cash Equivalents


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Cash on hand and petty cash	450	450
Checking accounts and demand deposits	2,248,954	1,434,939
Time deposits	7,647,200	10,918,646
	9,896,604	12,354,035

The Group transacts with a variety of financial institutions all with high credit quality to disperse credit risk, so it expects that the probability of counterparty default is remote.

No cash and cash equivalents of the Group were pledged to others.

Accounts receivable - Summary of Accounts and notes receivable (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Jan. 01, 2022 TWD ($)
Disclosure of financial assets [Line Items]
Accounts receivable	$ 5,326,381	$ 173,951	$ 4,381,563
Accounts receivable [member]
Disclosure of financial assets [Line Items]
Accounts receivable	5,328,835		4,384,232	$ 6,344,246
Loss allowance [member]
Disclosure of financial assets [Line Items]
Accounts receivable	$ (2,454)		$ (2,669)

Interest income (Tables)

12 Months Ended

Dec. 31, 2023

Disclosure of Interest Income [Abstract]

Disclosure of Interest Income


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Bank deposits	8,772	56,612	191,265
Financial assets at amortized cost	1,187	587	1,861
Other interest income	21	—	63
	9,980	57,199	193,189

Segment Information - Net Revenue from Customers Representing at Least 10% of Total Revenue (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of major customers [Line Items]
Net revenue	$ 21,356,228	$ 697,460	$ 23,517,064	$ 27,400,035
Percentage of total revenue	100.00%	100.00%	100.00%	100.00%
Customer A [member]
Disclosure of major customers [Line Items]
Net revenue	$ 5,251,529		$ 4,705,064	$ 5,681,277
Percentage of total revenue	25.00%	25.00%	20.00%	21.00%
Customer B [Member]
Disclosure of major customers [Line Items]
Net revenue	$ 2,834,188		$ 1,868,583	$ 2,484,611
Percentage of total revenue	13.00%	13.00%	8.00%	9.00%
Customer M [Member]
Disclosure of major customers [Line Items]
Net revenue	$ 1,320,905		$ 2,278,645	$ 2,832,088
Percentage of total revenue	6.00%	6.00%	10.00%	10.00%

- Definition

The income arising in the course of an entity's ordinary activities. Income is increases in assets, or decreases in liabilities, that result in increases in equity, other than those relating to contributions from holders of equity claims.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2023-01-01
-Paragraph 28
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2023-en-r&anchor=para_28_a&doctype=Standard
-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2023-01-01
-Paragraph 23
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2023-en-r&anchor=para_23_a&doctype=Standard
-URIDate 2023-03-23

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2023-01-01
-Paragraph 32
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2023-en-r&anchor=para_32&doctype=Standard
-URIDate 2023-03-23

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 5
-IssueDate 2023-01-01
-Paragraph 33
-Subparagraph b
-Clause i
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=5&code=ifrs-tx-2023-en-r&anchor=para_33_b_i&doctype=Standard
-URIDate 2023-03-23

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2023-01-01
-Paragraph 33
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2023-en-r&anchor=para_33_a&doctype=Standard
-URIDate 2023-03-23

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2023-01-01
-Paragraph 34
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2023-en-r&anchor=para_34&doctype=Standard
-URIDate 2023-03-23

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 12
-IssueDate 2023-01-01
-Paragraph B12
-Subparagraph b
-Clause v
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2023-en-r&anchor=para_B12_b_v&doctype=Appendix&subtype=B
-URIDate 2023-03-23

Reference 8: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 12
-IssueDate 2023-01-01
-Paragraph B10
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2023-en-r&anchor=para_B10_b&doctype=Appendix&subtype=B
-URIDate 2023-03-23

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2023-01-01
-Paragraph 82
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2023-en-r&anchor=para_82_a&doctype=Standard
-URIDate 2023-03-23

Reference 10: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 1
-IssueDate 2023-01-01
-Paragraph 103
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2023-en-r&anchor=para_103&doctype=Standard
-URIDate 2023-03-23

Reference 11: http://www.xbrl.org/2003/role/exampleRef
-Name IAS
-Number 1
-IssueDate 2023-01-01
-Paragraph 102
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2023-en-r&anchor=para_102&doctype=Standard
-URIDate 2023-03-23

+ Details

Capital management (Tables)

12 Months Ended

Dec. 31, 2023

Disclosure of objectives, policies and processes for managing capital [abstract]

Summary of Group Monitors Capital using Liabilities to Assets Ratio

The liabilities to assets ratio at December 31, 2022 and 2023 were as follows:


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Total liabilities	20,303,685	21,397,287
Total assets	44,942,945	46,160,484
Liabilities to assets ratio	45.18%	46.35%

Investments accounted for using equity method

12 Months Ended

Dec. 31, 2023

Investments accounted for using equity method [abstract]

Investments accounted for using equity method

12.

Investments accounted for using equity method


Associates	December 31, 2022	December 31, 2023
	NT$000	NT$000
JMC ELECTRONICS CO., LTD. (“JMC”)	267,070	277,076
Unimos Microelectronics (Shanghai) Co., Ltd. (“Unimos Shanghai”) (Note)	4,086,378	—
Daypower Energy	—	13,466
	4,353,448	290,542

Note: On December 21, 2023, the Company's Board of Directors approved its subsidiary ChipMOS BVI to sell the investment accounted for using equity method in Unimos Shanghai and reclassified the investment as non-current assets held for sale. Information relating to non-current assets held for sale is provided in Note 14.

The carrying amount of the Group’s interests in all individually immaterial associates and the Group’s share of the operating results are summarized below:

As of December 31, 2022 and 2023, the carrying amount of the Group’s individually immaterial associates amounted to NT$4,353,448 thousand and NT$290,542 thousand, respectively.


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Profit for the year from continuing operations	625,733	453,715	1,714
Other comprehensive income (loss), net of income tax	28,843	(28,254)	12,993
Total comprehensive income	654,576	425,461	14,707

JMC has quoted market prices. As of December 31, 2022 and 2023, the fair value was NT$249,000 thousand and NT$303,780 thousand, respectively.

Both JMC and Daypower Energy are recognized as investment accounted for using equity method given that the Company retains significant influence by holding one seat in JMC’s and Daypower Energy’s Board of Directors.

Financial risk management and fair values of financial instruments

12 Months Ended

Dec. 31, 2023

Disclosure of detailed information about financial instruments [abstract]

Financial risk management and fair values of financial instruments

41.

Financial risk management and fair values of financial instruments

Financial instruments

(a)

Financial instruments by category


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Financial assets
Financial assets at fair value through profit or loss
Financial assets mandatorily measured at fair value through profit or loss	128,224	42,735
Financial assets at fair value through other comprehensive income
Designation of equity instruments	338,102	120,317
Financial assets at amortized cost
Cash and cash equivalents	9,896,604	12,354,035
Financial assets at amortized cost	136,093	78,477
Accounts receivable	4,381,563	5,326,381
Other receivables	131,863	44,576
Refundable deposits	21,771	20,707
	15,034,220	17,987,228
Financial liabilities
Financial liabilities at amortized cost
Notes payable	132	484
Accounts payable	560,802	784,919
Other payables	3,796,481	3,479,045
Other payables – related parties	—	58,549
Long-term bank loans (including current portion)	13,967,801	14,911,719
Lease liabilities (including current portion)	920,402	1,065,401
Guarantee deposits	21,600	21,235
	19,267,218	20,321,352

(b)

Risk management policies

The Group’s risk management objective is to manage the market risk, credit risk and liquidity risk related to its operating activities. The Group identifies, measures, and manages such risks by its policies and preferences.

ii)

The Group has established appropriate policies, procedures and internal controls for financial risk management. Before entering into significant financial transactions, a due approval process must be carried out by the Board of Directors based on related protocols and internal control procedures. The Group complies with its financial risk management policies at all times.

iii)

In order to minimize and manage financial risks, the Group’s overall risk management program focuses on analyzing, identifying, and evaluating financial risk factors that may potentially have adverse effects on the Group’s financial position, and provide feasible solutions to avoid those factors.

(c)

Significant financial risks and degrees of financial risks

Market risk

The Group’s market risk is the risk that the fair value or future cash flows of a financial instrument will fluctuate because of changes in market prices. Market risks comprise foreign currency risk, interest rate risk, and other price risks.

In practice, the risk variable rarely changes individually, and the change of each risk variable is usually correlative. The following sensitivity analysis did not consider the interaction of each risk variable.

Foreign exchange risk

The Group’s exposure to the risk of changes in foreign exchange rates relates primarily to the Group’s operating activities (when revenue or expense is denominated in a different currency from the Company’s and its subsidiaries’ functional currency) and the Group’s net investments in foreign operations.

The Group applies natural hedges by using accounts receivable and accounts payable denominated in the same currency. However, this natural hedge does not concur with the requirement for hedge accounting. Furthermore, as net investments in foreign operations are for strategic purposes, they are not hedged by the Group.

The Group’s foreign currency exposure gives rise to market risks associated with exchange rate movements against the NT dollar for cash and cash equivalents, accounts receivable, other receivables, bank loans, accounts payable and other payables (including related parties).

The Group’s businesses involve some non-functional currency operations. The information on assets and liabilities denominated in foreign currencies whose values would be materially affected by the exchange rate fluctuations is as follows:


	December 31, 2022
	Foreign currency	Exchange rate	Carrying amount (NT$000)
(Foreign currency: functional currency)
Financial assets
Monetary items
US$000	208,989	30.7100	6,418,052
JPY000	114,940	0.2324	26,712
RMB000	7,199	4.4080	31,733
Non-monetary items
JPY000	1,454,830	0.2324	338,102
RMB000	927,037	4.4080	4,086,378
Financial liabilities
Monetary items
US$000	11,031	30.7100	338,762
JPY000	1,587,732	0.2324	368,989


	December 31, 2023
	Foreign currency	Exchange rate	Carrying amount (NT$000)
(Foreign currency: functional currency)
Financial assets
Monetary items
US$000	149,837	30.7050	4,600,745
JPY000	188,904	0.2172	41,030
RMB000	5,595	4.3270	24,210
Non-monetary items
JPY000	553,946	0.2172	120,317
Financial liabilities
Monetary items
US$000	21,175	30.7050	650,178
JPY000	1,102,264	0.2172	239,412

The total exchange (losses) gains, including realized and unrealized (losses) gains arising from significant foreign exchange variations on monetary items held by the Group for the years ended December 31, 2021, 2022 and 2023, amounted to (NT$89,152) thousand, NT$448,097 thousand and NT$78,170 thousand, respectively.

Analysis of foreign currency market risk arising from significant foreign exchange variations:


	Year ended December 31, 2021
	Sensitivity analysis
	Change in exchange rate	Effect on profit (loss) (NT$000)	Effect on other comprehensive income (NT$000)
Financial assets
Monetary items
US$000	5%	260,390	—
JPY000	5%	1,702	—
RMB000	5%	1,074	—
Financial liabilities
Monetary items
US$000	5%	73,410	—
JPY000	5%	13,103	—


	Year ended December 31, 2022
	Sensitivity analysis
	Change in exchange rate	Effect on profit (loss) (NT$000)	Effect on other comprehensive income (NT$000)
Financial assets
Monetary items
US$000	5%	320,903	—
JPY000	5%	1,336	—
RMB000	5%	1,587	—
Financial liabilities
Monetary items
US$000	5%	16,938	—
JPY000	5%	18,449	—


	Year ended December 31, 2023
	Sensitivity analysis
	Change in exchange rate	Effect on profit (loss) (NT$000)	Effect on other comprehensive income (NT$000)
Financial assets
Monetary items
US$000	5%	230,037	—
JPY000	5%	2,052	—
RMB000	5%	1,211	—
Financial liabilities
Monetary items
US$000	5%	32,509	—
JPY000	5%	11,971	—

Price risk

The Group’s financial instruments, which are exposed to price risk, are the financial assets at fair value through profit or loss and financial assets at fair value through other comprehensive income. To manage its price risk arising from investments in financial instruments, the Group diversifies its portfolio. Diversification of the portfolio is in accordance with the limits set by the Group.

The Group invests in beneficiary certificates and listed stocks issued by the domestic companies. The prices of equity securities would change due to change of the future value of investee companies. For the years ended December 31, 2021, 2022 and 2023, it is estimated that the prices of equity securities increase or decrease by 1%, with all other variables held constant, would increase or decrease the Group’s profit before income tax by NT$3,600 thousand, NT$1,282 thousand and NT$427 thousand, respectively.

The Group’s investments in financial instruments comprise foreign unlisted stocks. The prices of financial instruments would change due to different valuation models and assumptions used. Analysis related to the effect on profit or other comprehensive income if these assumptions change is provided in Note 41 b) (g).

Interest rate risk on cash flow and fair value

Interest rate risk is the risk that the fair value or future cash flows of a financial instrument will fluctuate because of changes in market interest rates. The Group’s exposure to the risk of changes in market interest rates relates primarily to the Group’s bank loans with floating interest rates. The Group manages its interest rate risk by having a balanced portfolio of fixed and variable rate bank loans. The Group reassesses the hedge management periodically to make sure it complies with the cost effectiveness.

The sensitivity analysis depends on the exposure of interest rate risk at the end of the reporting period.

Analysis of debt with floating interest rates is based on the assumption that the outstanding debt at the end of the reporting period is outstanding throughout the period. The degree of variation the Group used to report to internal management is increase or decrease of 1% in interest rates which is assessed as the reasonable degree of variation by the management.

For the years ended December 31, 2021, 2022 and 2023, it is estimated that a general increase or decrease of 1% in interest rates, with all other variables held constant, would decrease or increase the Group’s profit before income tax approximately by NT$102,489 thousand, NT$140,561 thousand and NT$149,723 thousand, respectively, mainly due to the Group’s floating rate on bank loans.

ii)

Credit risk

Credit risk is the risk that a counterparty will not meet its obligations under a financial instrument or customer contract, leading to a financial loss, mainly resulted from its operating activities (primarily accounts receivable) and from its financing activities (primarily deposits with banks and financial instruments). The Group is exposed to credit risk arising from the carrying amount of the financial assets recognized in the consolidated statements of financial position.

Each business unit performs ongoing credit evaluations of its debtors’ financial conditions according to the Group’s established policies, procedures and controls relating to customer credit risk management. The Group maintains an account for loss allowance based upon the available facts and circumstances, history of collection and write-off experiences of all trade and other receivables which consequently minimize the Group’s exposure to bad debts.

Credit risk from balances with banks and financial institutions is managed by the Group’s finance unit in accordance with the Group’s policies. Transaction counterparty of the Group is determined through its internal controls policy. For banks and financial institutions, only parties rated above BBB+ by Taiwan Ratings are accepted. The probability of counterparty default is remote, so there is no significant credit risk.

The Group adopts the assumptions under IFRS 9, “Financial Instruments” and the default is deemed to have occurred when the contract payments are past due over 90 days.

The Group categorized contract assets, accounts receivable and other receivables by characteristics of credit risk and applied the simplified approach using loss rate methodology to estimate expected credit loss.

The Group referred to the forecastability of business monitoring indicators published by the ROC National Development Council to adjust the loss rate which is based on historical and current information when assessing the future default possibility of contract assets, accounts receivable and other receivables. As of December 31, 2022 and 2023 the loss rate methodologies are as follows:


	December 31, 2022
	Contract assets	Accounts receivable (including related parties)	Other receivables (including related parties)
	NT$000	NT$000	NT$000
Expected loss rate	0.060%	0.060%	0.060%
Total carrying amount	381,587	4,384,232	131,908
Loss allowance	(229)	(2,669)	(45)


	December 31, 2023
	Contract assets	Accounts receivable (including related parties)	Other receivables (including related parties)
	NT$000	NT$000	NT$000
Expected loss rate	0.045%	0.045%	0.045%
Total carrying amount	384,057	5,328,835	44,589
Loss allowance	(174)	(2,454)	(13)

Under the simplified approach, movements in relation to loss allowance for contract assets, accounts receivable, and other receivables are as follows:


	2021
	Contract assets	Accounts receivable (including related parties)	Other receivables (including related parties)
	NT$000	NT$000	NT$000
January 1	(117)	(1,620)	(10)
Provision for impairment loss	(3)	(290)	(6)
December 31	(120)	(1,910)	(16)


	2022
	Contract assets	Accounts receivable (including related parties)	Other receivables (including related parties)
	NT$000	NT$000	NT$000
January 1	(120)	(1,910)	(16)
Provision for impairment loss	(109)	(759)	(29)
December 31	(229)	(2,669)	(45)


	2023
	Contract assets	Accounts receivable (including related parties)	Other receivables (including related parties)
	NT$000	NT$000	NT$000
January 1	(229)	(2,669)	(45)
Reversal of impairment loss	55	215	32
December 31	(174)	(2,454)	(13)

The Group’s recorded financial assets at amortized cost include time deposits with contract period over 3 months and restricted bank deposits. Because of the low credit risk, expected credit losses for the period are measured through a loss allowance at an amount equal to the 12-month expected credit losses. There is no significant provision for the losses.

iii)

Liquidity risk

The Group manages and maintains adequate cash and cash equivalents to finance the Group’s operations, and minimize the impact from cash flow fluctuations. The Group also monitors its debt financing plans to ensure it is in compliance with the financial covenants required under its loan agreements.

The primary source of liquidity for the Group is from bank loans. See Note 17 for details of the unused credit lines of the Group as of December 31, 2022 and 2023.

The contractual undiscounted cash flows of notes payable, accounts payable and other payables (including related parties) due within one year and is equivalent to its carrying amount. Except for the aforementioned, the table below summarizes the maturity profile of the Group’s non-derivative financial liabilities based on the earliest repayment dates and contractual undiscounted payments, including principal and interest. The Group does not consider the probability of early repayments requested by the banks.


	December 31, 2022
	Within 1 year	1 to 3 years	3 to 5 years	Over 5 years	Total
	NT$000	NT$000	NT$000	NT$000	NT$000
Non-derivative financial liabilities
Long-term bank loans	1,699,165	5,675,288	5,354,335	1,914,280	14,643,068
Lease liabilities	174,460	182,767	57,057	704,503	1,118,787
Guarantee deposits	—	—	—	21,600	21,600
	1,873,625	5,858,055	5,411,392	2,640,383	15,783,455


	December 31, 2023
	Within 1 year	1 to 3 years	3 to 5 years	Over 5 years	Total
	NT$000	NT$000	NT$000	NT$000	NT$000
Non-derivative financial liabilities
Long-term bank loans	2,469,744	7,506,844	4,273,199	1,330,797	15,580,584
Lease liabilities	267,759	250,104	57,856	681,975	1,257,694
Guarantee deposits	—	—	—	21,235	21,235
	2,737,503	7,756,948	4,331,055	2,034,007	16,859,513

The difference between the floating interest rates and estimated interest rates will affect the non-derivative financial liabilities stated above.

Fair value information

(a)

The different levels of inputs used in valuation techniques to measure fair value of financial and non-financial instruments are defined as follows:

Level 1: Quoted prices (unadjusted) in active markets for identical assets or liabilities that can be accessed at the measurement date. An active market is a market in which trading for the asset or liability takes place with sufficient frequency and volume to provide pricing information on an ongoing basis.

Level 2: Inputs other than quoted prices from Level 1 that are observable information for the asset or liability, either directly or indirectly.

Level 3: Unobservable inputs for the asset or liability. The fair value of the Group’s investment in equity investment without active market is included in Level 3.

(b)

The carrying amounts of cash and cash equivalents, financial assets at amortized cost, contract assets, accounts receivable, other receivables, refundable deposits, long-term bank loans, notes payable, accounts payable, other payables (including related parties), and guarantee deposits are approximate to their fair values.

(c)

The related information of financial and non-financial instruments measured at fair value by level based on the nature, characteristics and risks of the assets and liabilities are as follows:

The related information of natures of the assets and liabilities are as follows:


	December 31, 2022
	Level 1	Level 2	Level 3	Total
	NT$000	NT$000	NT$000	NT$000
Assets
Recurring fair value measurements
Financial assets at fair value through profit or loss
- Listed stocks	128,224	—	—	128,224
Financial assets at fair value through other comprehensive income
- Foreign unlisted stocks	—	—	338,102	338,102
	128,224	—	338,102	466,326


	December 31, 2023
	Level 1	Level 2	Level 3	Total
	NT$000	NT$000	NT$000	NT$000
Assets
Recurring fair value measurements
Financial assets at fair value through profit or loss
- Listed stocks	42,735	—	—	42,735
Financial assets at fair value through other comprehensive income
- Foreign unlisted stocks	—	—	120,317	120,317
	42,735	—	120,317	163,052

ii)

The methods and assumptions the Group used to measure fair value are as follows:

The fair value of the Group’s listed stocks is measured by using the market quoted prices, which is categorized within Level 1 fair value.

Except for listed stocks with active markets, the fair value of the Group’s other financial instruments is measured by using valuation techniques or by reference to counterparty quotes. The fair value of financial instruments measured by using valuation techniques can be referred to current fair value of instruments with similar terms and characteristics in substance, discounted cash flow method or other valuation methods, including calculated by applying model using market information available at the consolidated statement of financial position date.

The Group’s financial instruments issued by foreign companies are measured by the comparable company valuation (EV/EBITDA ratio and P/B ratio).

The Group takes into account adjustments for credit risks to measure the fair value of financial and non-financial instruments to reflect credit risk of the counterparty and the Group’s credit quality.

(d)

The following table shows the movements of Level 3 for the years ended December 31, 2022 and 2023:


	Equity instruments
	2022	2023
	NT$000	NT$000
January 1	384,521	338,102
Gains or losses recognized in other comprehensive income
Recorded as unrealized loss on valuation of financial assets at fair value through other comprehensive income	(46,419)	(217,785)
Purchases	—	12,500
Reclassified as investments accounted for using equity method	—	(12,500)
December 31	338,102	120,317

(e)

The Group performs the fair value measurements being categorized within Level 3 with assistance from specialist. Such assessment is to ensure the valuation results are reasonable by applying independent information to make results close to current market conditions, confirming the resource of information is independent, reliable and in line with other resources and represented as the exercisable price, and frequently calibrating valuation model, updating inputs used to the valuation model and making any other necessary adjustments to the fair value.

(f)

The following is the qualitative information and sensitivity analysis of changes in significant unobservable inputs under valuation model used in Level 3 fair value measurement:


	Fair value as of December 31, 2022	Valuation technique	Significant unobservable input	Range	Relationship of inputs to fair value
	NT$000
Non-derivative equity instrument:
Foreign unlisted stocks	338,102	Comparable companies	Enterprise value to EBITDA multiple	4.82	The higher the multiple, the higher the fair value
			Discount for lack of marketability	15.80%	The higher the discount for lack of marketability, the lower the fair value


	Fair value as of December 31, 2023	Valuation technique	Significant unobservable input	Range	Relationship of inputs to fair value
	NT$000
Non-derivative equity instrument:
Foreign unlisted stocks	120,317	Comparable companies	Enterprise value to EBITDA multiple	8.23	The higher the multiple, the higher the fair value
			Price to book ratio multiple	1.64	The higher the multiple, the higher the fair value
			Discount for lack of marketability	15.70%	The higher the discount for lack of marketability, the lower the fair value

(g)

The Group has carefully assessed the valuation models and assumptions used to measure fair value. However, use of different valuation models or assumptions may result in different measurement. The following is the effect of profit or loss or of other comprehensive income from financial assets categorized within Level 3 if the inputs used to valuation models have changed:

          
         December 31, 2022

          
         Recognized in 
profit or loss

         Recognized in other
comprehensive income

          
         Input

         Change

         Favorable
change

         Unfavorable
change

         Favorable
change

         Unfavorable
change

         Financial assets:

           Foreign unlisted stocks

         Enterprise value to 
  EBITDA multiple

         ±1%

         —

         —

         2,876

         2,883

          
         Discount for lack 
  of marketability

         ±1%

         —

         —

         3,990

         4,039


			December 31, 2023
			Recognized in profit or loss		Recognized in other comprehensive income
	Input	Change	Favorable change	Unfavorable change	Favorable change	Unfavorable change
			NT$000	NT$000	NT$000	NT$000
Financial assets:
Foreign unlisted stocks	Enterprise value to EBITDA multiple	±1%	—	—	748	709
	Price to book ratio multiple	±1%	—	—	30	30
	Discount for lack of marketability	±1%	—	—	1,453	1,413
			—	—	2,231	2,152

Pledged assets - Certain Assets Provided as Collateral Mainly for Long-term Bank Loans and Leases (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disclosure assets pledged as collateral [Line Items]
Purpose	Lease and bank loan
Non-current financial assets at amortized cost	$ 37,411	$ 37,362
Assets pledged as collateral for liabilities	$ 13,964,988	14,080,591
Land [member]
Disclosure assets pledged as collateral [Line Items]
Purpose	Bank loan
Property, plant and equipment, net	$ 454,738	452,738
Buildings [member]
Disclosure assets pledged as collateral [Line Items]
Purpose	Bank loan
Property, plant and equipment, net	$ 5,299,221	5,385,508
Machinery and equipment [member]
Disclosure assets pledged as collateral [Line Items]
Purpose	Bank loan
Property, plant and equipment, net	$ 8,173,618	$ 8,204,983

Other gains and losses

12 Months Ended

Dec. 31, 2023

Disclosure of Other gains and losses [Abstract]

Other gains and losses

27.

Other gains and losses


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Foreign exchange (losses) gains, net	(89,152)	448,097	78,170
Gain (loss) on valuation of financial assets at fair value through profit or loss	15,262	(69,404)	39,254
Reimbursement of ADSs service charge	2,284	2,412	2,121
Compensation income	1,524	174	20
Others	4,253	5,288	15,936
	(65,829)	386,567	135,501

Finance costs

12 Months Ended

Dec. 31, 2023

Finance costs [Abstract]

Finance costs

28.

Finance costs


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Interest expense
Bank loans	116,946	138,731	254,892
Lease liabilities	15,245	14,556	18,757
Others	—	8	—
Less: Amounts capitalized in qualifying assets	(11,193)	(10,856)	(7,692)
	120,998	142,439	265,957
Finance expense	10,186	10,840	433
	131,184	153,279	266,390

Other equity interest (Tables)

12 Months Ended

Dec. 31, 2023

Other Equity Interests [Abstract]

Summary of Other Equity Interest


	2021
	Financial statements translation differences of foreign operations	Unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income	Total
	NT$000	NT$000	NT$000
January 1	(61,330)	194,716	133,386
Currency translation differences
- The Company	(24,695)	—	(24,695)
Evaluation adjustment
- The Company	—	122,514	122,514
- Associates	—	21,094	21,094
Evaluation adjustment related tax
- The Company	—	(30,459)	(30,459)
December 31	(86,025)	307,865	221,840


	2022
	Financial statements translation differences of foreign operations	Unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income	Total
	NT$000	NT$000	NT$000
January 1	(86,025)	307,865	221,840
Currency translation differences
- The Company	68,656	—	68,656
Evaluation adjustment
- The Company	—	(46,419)	(46,419)
- Associates	—	(28,353)	(28,353)
Evaluation adjustment related tax
- The Company	—	12,559	12,559
December 31	(17,369)	245,652	228,283


	2023
	Financial statements translation differences of foreign operations	Unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income	Equity directly related to non-current assets held for sale	Total
	NT$000	NT$000	NT$000	NT$000
January 1	(17,369)	245,652	—	228,283
Currency translation differences
- The Company	16,713	—	—	16,713
- Non-current assets held for sale	—	—	(43,094)	(43,094)
Evaluation adjustment
- The Company	—	(217,785)	—	(217,785)
- Associates	—	12,605	—	12,605
Evaluation adjustment related tax
- The Company	—	51,638	—	51,638
December 31	(656)	92,110	(43,094)	48,360

Retained earnings (Tables)

12 Months Ended

Dec. 31, 2023

Retained earnings [abstract]

Summary of Distribution Towards Legal Reserve and Cash Dividend

The appropriations and dividends per share are as follows:


	2020		2021		2022
	Amount	Cash distribution per share	Amount	Cash distribution per share	Amount	Cash distribution per share
	NT$000	NT$	NT$000	NT$	NT$000	NT$
Legal reserve	232,611		505,482		354,986
Special reserve	(19,802)		—		—
Cash dividend	1,599,928	2.20	3,127,133	4.30	1,672,652	2.30

Label	Element	Value
Additional paid-in capital [member]
Additional paid-in capital	ifrs-full_AdditionalPaidinCapital	$ 6,055,773,000
Additional paid-in capital [member] \| Others [Member]
Additional paid-in capital	ifrs-full_AdditionalPaidinCapital	12,290,000
Additional paid-in capital [member] \| Share premium [member]
Additional paid-in capital	ifrs-full_AdditionalPaidinCapital	$ 6,043,483,000

Property, plant and equipment, net (Tables)

12 Months Ended

Dec. 31, 2023

Disclosure of detailed information about property, plant and equipment [abstract]

Summary of Property, Plant and Equipment, Net


	2021
	Land	Buildings	Machinery and equipment	Tools	Others	Construction in progress and equipment to be inspected	Total
	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000
January 1
Cost	452,738	11,212,129	53,246,474	5,451,547	2,185,299	639,607	73,187,794
Accumulated depreciation and impairment	—	(7,119,843)	(41,898,177)	(4,499,186)	(1,675,902)	—	(55,193,108)
	452,738	4,092,286	11,348,297	952,361	509,397	639,607	17,994,686
January 1	452,738	4,092,286	11,348,297	952,361	509,397	639,607	17,994,686
Additions	—	1,345	11,829	407	189	6,538,932	6,552,702
Disposals	—	—	(66,873)	(9,502)	—	—	(76,375)
Reclassifications	—	673,208	4,890,400	690,346	241,656	(6,495,610)	—
Depreciation expenses	—	(423,283)	(2,896,612)	(795,622)	(239,515)	—	(4,355,032)
Impairment losses	—	—	(4,843)	—	—	—	(4,843)
Exchange adjustment	—	—	(13)	—	(4)	—	(17)
December 31	452,738	4,343,556	13,282,185	837,990	511,723	682,929	20,111,121
December 31
Cost	452,738	11,877,419	57,176,339	5,574,316	2,345,204	682,929	78,108,945
Accumulated depreciation and impairment	—	(7,533,863)	(43,894,154)	(4,736,326)	(1,833,481)	—	(57,997,824)
	452,738	4,343,556	13,282,185	837,990	511,723	682,929	20,111,121


	2022
	Land	Buildings	Machinery and equipment	Tools	Others	Construction in progress and equipment to be inspected	Total
	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000
January 1
Cost	452,738	11,877,419	57,176,339	5,574,316	2,345,204	682,929	78,108,945
Accumulated depreciation and impairment	—	(7,533,863)	(43,894,154)	(4,736,326)	(1,833,481)	—	(57,997,824)
	452,738	4,343,556	13,282,185	837,990	511,723	682,929	20,111,121
January 1	452,738	4,343,556	13,282,185	837,990	511,723	682,929	20,111,121
Additions	—	3,780	6,748	636	—	4,907,318	4,918,482
Disposals	—	—	(46,084)	(2,597)	—	—	(48,681)
Reclassifications	—	1,503,432	2,603,381	685,481	294,765	(5,086,047)	1,012
Depreciation expenses	—	(465,260)	(3,075,191)	(724,813)	(257,817)	—	(4,523,081)
Impairment losses	—	—	(12,721)	—	—	—	(12,721)
Exchange adjustment	—	—	50	—	23	—	73
December 31	452,738	5,385,508	12,758,368	796,697	548,694	504,200	20,446,205
December 31
Cost	452,738	13,379,852	59,197,255	5,716,357	2,615,959	504,200	81,866,361
Accumulated depreciation and impairment	—	(7,994,344)	(46,438,887)	(4,919,660)	(2,067,265)	—	(61,420,156)
	452,738	5,385,508	12,758,368	796,697	548,694	504,200	20,446,205


	2023
	Land	Buildings	Machinery and equipment	Tools	Others	Construction in progress and equipment to be inspected	Total
	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000
January 1
Cost	452,738	13,379,852	59,197,255	5,716,357	2,615,959	504,200	81,866,361
Accumulated depreciation and impairment	—	(7,994,344)	(46,438,887)	(4,919,660)	(2,067,265)	—	(61,420,156)
	452,738	5,385,508	12,758,368	796,697	548,694	504,200	20,446,205
January 1	452,738	5,385,508	12,758,368	796,697	548,694	504,200	20,446,205
Additions	—	1,303	5,579	291	1,376	3,219,922	3,228,471
Disposals	—	—	(16,574)	(11,038)	—	—	(27,612)
Reclassifications	2,000	469,597	1,787,140	586,090	226,610	(3,071,437)	—
Depreciation expenses	—	(557,187)	(3,043,504)	(635,227)	(262,388)	—	(4,498,306)
Impairment losses	—	—	(9,236)	—	—	—	(9,236)
Exchange adjustment	—	—	—	—	(19)	—	(19)
December 31	454,738	5,299,221	11,481,773	736,813	514,273	652,685	19,139,503
December 31
Cost	454,738	13,850,418	60,650,428	5,959,251	2,774,055	652,685	84,341,575
Accumulated depreciation and impairment	—	(8,551,197)	(49,168,655)	(5,222,438)	(2,259,782)	—	(65,202,072)
	454,738	5,299,221	11,481,773	736,813	514,273	652,685	19,139,503

Capitalization Interest and Capitalization Interest Rate Applied Related to Property, Plant and Equipment


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Amount of interest capitalized	11,193	10,856	7,692
Range of the interest rates for capitalization	1.1358%	1.0094%	1.4588%

Financial Risk Management and Fair Values of Financial Instruments - Summary of Movements of Level 3 (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of detailed information about financial instruments [Line Items]
Gains or losses recognized in profit or loss Recorded as non-operating income (expenses)	$ (39,254)	$ (1,282)	$ 69,404	$ (15,262)
Gains or losses recognized in other comprehensive gains (losses) Recorded as unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income	(217,785)	$ (7,113)	(46,419)	122,514
Level 3 [member] \| Debt instruments [member]
Disclosure of detailed information about financial instruments [Line Items]
Movement of financial instruments beginning balance	338,102		384,521
Movement of financial instruments ending balance			338,102	$ 384,521
Level 3 [member] \| Equity instruments [member]
Disclosure of detailed information about financial instruments [Line Items]
Movement of financial instruments beginning balance	338,102
Gains or losses recognized in other comprehensive gains (losses) Recorded as unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income	(217,785)		(46,419)
Purchases	12,500
Reclassified as investments accounted for using equity method	(12,500)
Movement of financial instruments ending balance	$ 120,317		$ 338,102

Retained Earnings - Details of Retained Earnings (Detail) - TWD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Legal reserve [member]
Disclosure of analysis of other comprehensive income by item [line items]
Appropriation of retained earnings	$ 354,986	$ 505,482	$ 232,611
Special Reserve [Member]
Disclosure of analysis of other comprehensive income by item [line items]
Appropriation of retained earnings			(19,802)
Cash Dividend [Member]
Disclosure of analysis of other comprehensive income by item [line items]
Appropriation of retained earnings	$ 1,672,652	$ 3,127,133	$ 1,599,928
Cash dividend, cash distribution per share	$ 2.3	$ 4.3	$ 2.2

Property, Plant and Equipment, Net - Capitalization Interest and Capitalization Interest Rate Applied Related to Property, Plant and Equipment (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of detailed information about property, plant and equipment [abstract]
Amount of interest capitalized	$ 7,692	$ 10,856	$ 11,193
Range of the interest rates for capitalization	1.4588%	1.0094%	1.1358%

Financial Assets at Fair Value Through Profit or Loss - Summary of Financial Assets at Fair Value Through Profit or Loss (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Financial Assets At Fair Value Through Profit Or Loss [line items]
Current financial assets mandatorily measured at fair value through profit or loss	$ 42,735	$ 1,396	$ 128,224
Listed stocks [member]
Financial Assets At Fair Value Through Profit Or Loss [line items]
Current financial assets mandatorily measured at fair value through profit or loss	53,747		171,988
Valuation adjustments [member]
Financial Assets At Fair Value Through Profit Or Loss [line items]
Current financial assets mandatorily measured at fair value through profit or loss	$ (11,012)		$ (43,764)

Segment information

12 Months Ended

Dec. 31, 2023

Disclosure of operating segments [abstract]

Segment information

42.

Segment information

General information

The Group engages mainly in the assembly and testing of semiconductors, memory modules and general investments. In accordance with IFRS 8, “Operating Segments”, the Group’s segments include Testing, Assembly, LCDD, Bumping and others as the five reportable segments.

Measurement of segment information

The Group’s reportable segments are strategic business units which provide different products and services. The accounting policies adopted by the operating segments are the same as the accounting policies described in Note 4.

Information about segment profit or loss

The segment information provided to the chief operating decision maker for the reportable segments is as follows:


	Year ended December 31, 2021
	Testing	Assembly	LCDD	Bumping	Others	Elimination	Total
	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000
Revenue
External customers	5,899,600	7,963,714	8,211,099	5,325,622	—	—	27,400,035
Inter-segment	—	—	—	—	43,808	(43,808)	—
Total revenue	5,899,600	7,963,714	8,211,099	5,325,622	43,808	(43,808)	27,400,035
Operating profit (loss)	1,814,021	857,304	2,336,394	561,642	(6,987)	15	5,562,389
Depreciation expenses	(921,999)	(576,138)	(2,579,150)	(549,020)	(7,805)	—	(4,634,112)
Share of profit of associates	—	—	—	—	1,211,177	(585,444)	625,733
Interest income	—	—	—	—	9,980	—	9,980
Interest expense	—	—	—	—	(120,998)	—	(120,998)
Purchase of property, plant and equipment	1,841,359	1,553,475	2,748,697	408,751	420	—	6,552,702


	Year ended December 31, 2022
	Testing	Assembly	LCDD	Bumping	Others	Elimination	Total
	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000
Revenue
External customers	5,243,997	6,705,898	7,288,642	4,278,527	—	—	23,517,064
Inter-segment	—	—	—	—	50,600	(50,600)	—
Total revenue	5,243,997	6,705,898	7,288,642	4,278,527	50,600	(50,600)	23,517,064
Operating profit (loss)	1,253,477	(93,585)	1,795,741	268,159	(6,821)	(292)	3,216,679
Depreciation expenses	(1,042,455)	(694,835)	(2,505,297)	(500,863)	(8,452)	—	(4,751,902)
Share of profit of associates	—	—	—	—	884,555	(430,840)	453,715
Interest income	—	—	—	—	57,199	—	57,199
Interest expense	—	—	—	—	(142,439)	—	(142,439)
Purchase of property, plant and equipment	1,086,682	957,790	2,677,489	196,521	—	—	4,918,482


	Year ended December 31, 2023
	Testing	Assembly	LCDD	Bumping	Others	Elimination	Total
	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000
Revenue
External customers	4,394,726	4,629,430	7,821,640	4,510,432	—	—	21,356,228
Inter-segment	—	—	—	—	59,481	(59,481)	—
Total revenue	4,394,726	4,629,430	7,821,640	4,510,432	59,481	(59,481)	21,356,228
Operating profit (loss)	514,707	(1,180,481)	2,058,285	522,386	(6,194)	(251)	1,908,452
Depreciation expenses	(1,065,689)	(722,462)	(2,547,253)	(435,709)	(8,220)	—	(4,779,333)
Share of profit of associates	—	—	—	—	420,393	(200,502)	219,891
Interest income	—	—	—	—	193,189	—	193,189
Interest expense	—	—	—	—	(265,957)	—	(265,957)
Purchase of property, plant and equipment	749,158	568,289	1,756,590	152,908	1,526	—	3,228,471

Reconciliation for segment income (loss)

Revenue from external customers and segment income (loss) reported to the chief operating decision maker are measured using the same method as for revenue and operating profit in the financial statements. Thus, no reconciliation is needed.

Information on products and services


	Year ended December 31,
	2021		2022		2023
	NT$000	%	NT$000	%	NT$000	%
Testing	5,899,600	22	5,243,997	22	4,394,726	20
Assembly	7,963,714	29	6,705,898	29	4,629,430	22
LCDD	8,211,099	30	7,288,642	31	7,821,640	37
Bumping	5,325,622	19	4,278,527	18	4,510,432	21
	27,400,035	100	23,517,064	100	21,356,228	100

Geographical information


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Revenue
ROC	21,608,567	18,671,142	17,287,574
Japan	1,768,460	1,989,805	1,176,163
PRC	1,899,362	1,970,943	1,729,908
Singapore	1,630,733	390,488	676,088
Others	492,913	494,686	486,495
	27,400,035	23,517,064	21,356,228


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Non-current assets
ROC	21,677,980	20,360,166
PRC	2,291	1,279
Others	576	6,122
	21,680,847	20,367,567

Major customer information

The information on the major customers which constituted more than 10% of the Group’s total revenue for the years ended December 31, 2021, 2022 and 2023 is as follows:


	Year ended December 31,
	2021		2022		2023
	NT$000	%	NT$000	%	NT$000	%
Customers
Customer A	5,681,277	21	4,705,064	20	5,251,529	25
Customer B	2,484,611	9	1,868,583	8	2,834,188	13
Customer M	2,832,088	10	2,278,645	10	1,320,905	6

Financial assets at amortized cost (Tables)

12 Months Ended

Dec. 31, 2023

Financial assets at amortized cost [Abstract]

Summary of Financial Assets at Amortized Cost


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Current:
Time deposits	98,731	41,066
Non-current:
Restricted bank deposits	37,362	37,411

Amounts recognized in profit or loss in relation to financial assets at amortized cost are listed below:


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Interest income	1,187	587	1,861

Pensions - Analysis of Timing of the Future Pension Payment (Detail) $ in Thousands	Dec. 31, 2023 TWD ($)
Disclosure of net defined benefit liability (asset) [Line Items]
Defined benefit plan expected future pension payments	$ 408,904
Within 1 year [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Defined benefit plan expected future pension payments	69,288
1-2 years [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Defined benefit plan expected future pension payments	42,487
2-5 years [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Defined benefit plan expected future pension payments	115,279
5-10 years [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Defined benefit plan expected future pension payments	$ 181,850

Significant disaster loss	12 Months Ended
Significant disaster loss	Dec. 31, 2023
Disclosure of significant disaster loss [abstract]
Significant disaster loss	38. Significant disaster loss None.

Revenue - Summary of Contract Assets (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Jan. 01, 2022
Disclosure Of Contract Assets In Relation To Revenue [Abstract]
Contract assets	$ 383,883	$ 381,358	$ 400,255

Other Payables - Summary of Other Payables (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Trade and other current payables [abstract]
Payable to equipment suppliers	$ 1,196,181		$ 1,405,931
Salaries and bonuses payable	994,651		1,002,577
Employees' compensation payable	250,181		447,303
Pension payable	16,825		16,541
Directors' remuneration payable	6,255		11,182
Interest payable	9,625		7,768
Other expense payable	1,005,327		905,179
Other payables	$ 3,479,045	$ 113,620	$ 3,796,481

Financial Risk Management and Fair Values of Financial Instruments - Summary of Movements in Relation to Loss Allowance for Contract Assets, Accounts Receivable and Other Receivables (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of detailed information about financial instruments [Line Items]
Financial assets beginning balance	$ 15,034,220
Financial assets ending balance	17,987,228	$ 15,034,220
Contract assets [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets beginning balance	(229)	(120)	$ (117)
Provision for impairment loss		(109)	(3)
Reversal of impairment loss	55
Financial assets ending balance	(174)	(229)	(120)
Accounts receivable including related parties [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets beginning balance	(2,669)	(1,910)	(1,620)
Provision for impairment loss		(759)	(290)
Reversal of impairment loss	215
Financial assets ending balance	(2,454)	(2,669)	(1,910)
Other receivable including related parties [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets beginning balance	(45)	(16)	(10)
Provision for impairment loss		(29)	(6)
Reversal of impairment loss	32
Financial assets ending balance	$ (13)	$ (45)	$ (16)

- Definition

The amount of assets that are: (a) cash; (b) an equity instrument of another entity; (c) a contractual right: (i) to receive cash or another financial asset from another entity; or (ii) to exchange financial assets or financial liabilities with another entity under conditions that are potentially favourable to the entity; or (d) a contract that will, or may be, settled in the entity’s own equity instruments and is: (i) a non-derivative for which the entity is, or may be, obliged to receive a variable number of the entity’s own equity instruments; or (ii) a derivative that will, or may be, settled other than by the exchange of a fixed amount of cash or another financial asset for a fixed number of the entity’s own equity instruments. For this purpose the entity’s own equity instruments do not include puttable financial instruments classified as equity instruments in accordance with paragraphs 16A-16B of IAS 32, instruments that impose on the entity an obligation to deliver to another party a pro rata share of the net assets of the entity only on liquidation and are classified as equity instruments in accordance with paragraphs 16C-16D of IAS 32, or instruments that are contracts for the future receipt or delivery of the entity’s own equity instruments. [Refer: Financial instruments, class [member]; Financial liabilities]

+ References + Details

Income Tax Expense - Additional Information (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Disclosure of income tax expense [Line Items]
Taxable temporary differences not recognized as deferred tax liabilities	$ 1,245,171	$ 1,080,272

Accounts receivable - Aging of Accounts Receivable which are Past Due but not Impaired (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Jan. 01, 2022 TWD ($)
Disclosure of financial assets [Line Items]
Current trade receivables	$ 5,326,381	$ 173,951	$ 4,381,563
Accounts receivable [member]
Disclosure of financial assets [Line Items]
Current trade receivables	5,328,835		4,384,232	$ 6,344,246
Accounts receivable [member] \| Current [member]
Disclosure of financial assets [Line Items]
Current trade receivables	5,326,523		4,357,073
Accounts receivable [member] \| Within 1 month [member]
Disclosure of financial assets [Line Items]
Current trade receivables	2,089		$ 27,159
Accounts receivable [member] \| 1-2 months
Disclosure of financial assets [Line Items]
Current trade receivables	$ 223

Financial Risk Management and Fair Values of Financial Instruments - Summary of Financial Instruments by Category (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Financial assets at fair value through profit or loss
Financial assets mandatorily measured at fair value through profit or loss	$ 42,735		$ 128,224
Financial assets at fair value through other comprehensive income
Designation of equity instruments	120,317		338,102
Financial assets at amortized cost
Cash and cash equivalents	12,354,035	$ 403,463	9,896,604
Financial assets at amortized cost	78,477		136,093
Accounts receivable	5,326,381	173,951	4,381,563
Other receivables	44,576	1,456	131,863
Refundable deposits	20,707	676	21,771
Financial assets	17,987,228		15,034,220
Financial liabilities at amortized cost
Notes payable	484	16	132
Accounts payable	784,919	25,634	560,802
Other payables	3,479,045	113,620	3,796,481
Other payables - related parties	58,549	1,912
Long-term bank loans (including current portion)	14,911,719		13,967,801
Lease liabilities (including current portion)	1,065,401		920,402
Guarantee deposits	21,235	$ 694	21,600
Financial liabilities	$ 20,321,352		$ 19,267,218

Inventories - Summary of Inventories (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Disclosure of inventories [Line Items]
Raw materials	$ 2,568,648	$ 3,210,409
Gross carrying amount [member]
Disclosure of inventories [Line Items]
Raw materials	2,754,911	3,316,039
Allowance for impairment losses [member]
Disclosure of inventories [Line Items]
Raw materials	$ (186,263)	$ (105,630)

Revenue

12 Months Ended

Dec. 31, 2023

Receivables from contracts with customers [abstract]

Revenue

23.

Revenue


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Revenue from contracts with customers	27,400,035	23,517,064	21,356,228

The Group is primarily engaged in the assembly and testing services of high-integration and high-precision integrated circuits, and recognized revenue based on the progress towards completion of performance obligation during the service period. Information on revenue disaggregation is provided in Note 42.

Contract assets

The Group has recognized the following contract assets in relation to revenue from contracts with customers:


	January 1, 2022	December 31, 2022	December 31, 2023
	NT$000	NT$000	NT$000
Contract assets	400,255	381,358	383,883

The information relating to loss allowance for contract assets is provided in Note 41 a).

All of the service contracts are for periods of one year or less. As permitted under IFRS 15, “Revenue from Contracts with Customers”, the transaction price allocated to these unsatisfied contracts is not disclosed.

Capital Surplus - Details of Capital Surplus (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Capital surplus [line items]
Changes in associates accounted for using equity method	$ 152	$ 4,834
Ending balance	6,055,773
Capital surplus [member]
Capital surplus [line items]
Beginning balance	6,055,621	6,050,787
Changes in associates accounted for using equity method	152	4,834
Ending balance	6,055,773	6,055,621
Capital surplus [member] \| Share premium [member]
Capital surplus [line items]
Beginning balance	6,043,483	6,043,483
Ending balance	6,043,483	6,043,483
Capital surplus [member] \| Others [member]
Capital surplus [line items]
Beginning balance	12,138	7,304
Changes in associates accounted for using equity method	152	4,834
Ending balance	$ 12,290	$ 12,138

Non-current Financial Assets at Fair Value Through Other Comprehensive Income - Summary Amounts recognized in other comprehensive income in relation to the financial assets at fair value through other comprehensive income (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Financial assets at fair value through other comprehensive income [abstract]
Foreign unlisted stocks	$ (217,785)	$ (7,113)	$ (46,419)	$ 122,514

Changes in liabilities from financing activities

12 Months Ended

Dec. 31, 2023

Disclosure of reconciliation of liabilities arising from financing activities [abstract]

Changes in liabilities from financing activities

34.

Changes in liabilities from financing activities


	2021
	Short-term bank loans	Long-term bank loans (including current portion)	Guarantee deposits	Lease liabilities	Total liabilities from financing activities
	NT$000	NT$000	NT$000	NT$000	NT$000
January 1	—	7,733,565	21,670	870,495	8,625,730
Changes in cash flow from financing activities	731,751	1,652,332	(45)	(289,668)	2,094,370
Adjustment of right-of-use assets	—	—	—	255,179	255,179
Amortization of loan fees	—	7,646	—	—	7,646
Amortization of interest expense	—	19,822	—	15,245	35,067
December 31	731,751	9,413,365	21,625	851,251	11,017,992


	2022
	Short-term bank loans	Long-term bank loans (including current portion)	Guarantee deposits	Lease liabilities	Total liabilities from financing activities
	NT$000	NT$000	NT$000	NT$000	NT$000
January 1	731,751	9,413,365	21,625	851,251	11,017,992
Changes in cash flow from financing activities	(731,751)	4,513,672	(25)	(237,869)	3,544,027
Adjustment of right-of-use assets	—	—	—	292,464	292,464
Amortization of loan fees	—	10,026	—	—	10,026
Amortization of interest expense	—	30,738	—	14,556	45,294
December 31	—	13,967,801	21,600	920,402	14,909,803


	2023
	Long-term bank loans (including current portion)	Guarantee deposits	Lease liabilities	Total liabilities from financing activities
	NT$000	NT$000	NT$000	NT$000
January 1	13,967,801	21,600	920,402	14,909,803
Changes in cash flow from financing activities	907,306	(365)	(293,383)	613,558
Adjustment of right-of-use assets	—	—	419,625	419,625
Amortization of interest expense	36,612	—	18,757	55,369
December 31	14,911,719	21,235	1,065,401	15,998,355

Inventories (Tables)

12 Months Ended

Dec. 31, 2023

Inventories [abstract]

Summary of Inventories


	December 31, 2022
	Cost	Allowance for impairment losses	Carrying amount
	NT$000	NT$000	NT$000
Raw materials	3,316,039	(105,630)	3,210,409


	December 31, 2023
	Cost	Allowance for impairment losses	Carrying amount
	NT$000	NT$000	NT$000
Raw materials	2,754,911	(186,263)	2,568,648

Cost of Inventories Recognized as an Expense


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Cost of revenue	20,103,735	18,611,515	17,723,687
Loss on abandonment	552	9,448	2,483
Allowance for (reversal of) inventory valuation and obsolescence loss	41,770	(15,956)	80,633
	20,146,057	18,605,007	17,806,803

Capital Management - Percentages of Liabilities to Assets Ratio Used for Monitoring Capital (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Disclosure of objectives, policies and processes for managing capital [abstract]
Total liabilities	$ 21,397,287	$ 698,801	$ 20,303,685
Total assets	$ 46,160,484	$ 1,507,527	$ 44,942,945
Liabilities to assets ratio	46.35%	46.35%	45.18%

Significant events after the reporting period - Additional Information (Detail)	Dec. 21, 2023
Significant events after the reporting period [Abstract]
Proportion of subsidiary owned equity investment accounted for using equity method	45.0242%

Cash and cash equivalents

12 Months Ended

Dec. 31, 2023

Cash and cash equivalents [abstract]

Cash and cash equivalents


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Cash on hand and petty cash	450	450
Checking accounts and demand deposits	2,248,954	1,434,939
Time deposits	7,647,200	10,918,646
	9,896,604	12,354,035

The Group transacts with a variety of financial institutions all with high credit quality to disperse credit risk, so it expects that the probability of counterparty default is remote.

No cash and cash equivalents of the Group were pledged to others.

Income Tax Expense - Deferred Tax Charged to Other Comprehensive Income (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Income tax relating to components of other comprehensive income [abstract]
Unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income	$ (51,638)		$ (12,559)	$ 30,459
Remeasurement of defined benefit obligations	2,140		44,447	(2,999)
Total	$ (49,498)	$ (1,617)	$ 31,888	$ 27,460

Other Payables

12 Months Ended

Dec. 31, 2023

Trade and other current payables [abstract]

Other Payables

16.

Other payables


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Payable to equipment suppliers	1,405,931	1,196,181
Salaries and bonuses payable	1,002,577	994,651
Employees’ compensation payable	447,303	250,181
Pension payable	16,541	16,825
Directors’ remuneration payable	11,182	6,255
Interest payable	7,768	9,625
Other expense payable	905,179	1,005,327
	3,796,481	3,479,045

Financial Risk Management and Fair Values of Financial Instruments - Summary of Natures of Assets and Liabilities (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value through profit or loss	$ 42,735	$ 128,224
Financial assets at fair value through other comprehensive income	120,317	338,102
Financial assets at fair value	163,052	466,326
Financial assets at fair value	17,987,228	15,034,220
Foreign unlisted stocks [member] \| Recurring fair value measurement [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value through other comprehensive income	120,317	338,102
Listed stocks [member] \| Recurring fair value measurement [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value through profit or loss	42,735	128,224
Level 1 [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value	42,735	128,224
Level 1 [member] \| Listed stocks [member] \| Recurring fair value measurement [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value through profit or loss	42,735	128,224
Level 3 [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value	120,317	338,102
Level 3 [member] \| Foreign unlisted stocks [member] \| Recurring fair value measurement [member]
Disclosure of detailed information about financial instruments [Line Items]
Financial assets at fair value through other comprehensive income	$ 120,317	$ 338,102

Financial assets at amortized cost

12 Months Ended

Dec. 31, 2023

Financial assets at amortized cost [Abstract]

Financial assets at amortized cost


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Current:
Time deposits	98,731	41,066
Non-current:
Restricted bank deposits	37,362	37,411

Amounts recognized in profit or loss in relation to financial assets at amortized cost are listed below:


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Interest income	1,187	587	1,861

Without taking into account any collateral held or other credit enhancements, the maximum exposure to credit risk in respect of the amount that best represents the financial assets at amortized cost held by the Group is the carrying amount at the end of each reporting period.

Information about the financial assets at amortized cost that were pledged to others as collateral is provided in Note 36.

Information relating to credit risk of financial assets at amortized cost is provided in Note 41 a).

Related party transactions (Tables)

12 Months Ended

Dec. 31, 2023

Summary of Significant Related Party Transactions

Names of related parties and relationship


Name		Relationship
Unimos Shanghai		Associate
JMC		Associate
Daypower Energy		Associate
Siliconware Precision Industries Co., Ltd. (“SPIL”)		Entity that has significant influence over the Company

Significant related party transactions

(a)

Payable to equipment suppliers


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Daypower Energy	—	58,549

(b)

Acquisition of property, plant and equipment


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
SPIL	—	—	35,261

Key Management Personnel Compensation

Key management personnel compensation


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Salaries and other short-term employee benefits	243,405	211,620	176,702
Post-employment compensation	2,156	2,197	2,158
	245,561	213,817	178,860

Finance Costs - Summary of Finance Costs (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Analysis of Finance Costs [abstract]
Bank loans	$ 254,892		$ 138,731	$ 116,946
Lease liabilities	18,757		14,556	15,245
Others			8
Less: Amounts capitalized in qualifying assets	(7,692)		(10,856)	(11,193)
Interest expense	265,957		142,439	120,998
Finance expense	433		10,840	10,186
Finance costs	$ 266,390	$ 8,700	$ 153,279	$ 131,184

Income Tax Expense - Major Components of Income Tax Expense (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Current income tax:
Current income tax on profits for the period	$ 426,878		$ 771,378	$ 1,109,752
Income tax on unappropriated retained earnings	85,607		159,744	227,467
Prior year income tax overestimation	(182,778)		(255,935)	(184,284)
Total current income tax	329,707		675,187	1,152,935
Deferred income tax:
Relating to origination and reversal of temporary differences	(29,046)		(87,012)	(54,617)
Income tax expense	$ 300,661	$ 9,819	$ 588,175	$ 1,098,318

- Definition

The aggregate amount included in the determination of profit (loss) for the period in respect of current tax and deferred tax. [Refer: Current tax expense (income); Deferred tax expense (income)]

+ References + Details

Investments accounted for using equity method - Additional Information (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Disclosure of associates [line items]
Carrying amount of investment in associates	$ 290,542	$ 9,489	$ 4,353,448
Individually Immaterial Associates [member]
Disclosure of associates [line items]
Carrying amount of investment in associates	290,542		4,353,448
JMC ELECTRONICS CO., LTD. [member]
Disclosure of associates [line items]
Investment in associates at fair value	303,780		249,000
Carrying amount of investment in associates	$ 277,076		$ 267,070

Supplemental cash flow information (Tables)

12 Months Ended

Dec. 31, 2023

Statement of cash flows [abstract]

Partial Cash Paid for Investing Activities

Property, plant and equipment


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Purchase of property, plant and equipment	6,552,702	4,918,482	3,228,471
Add: Beginning balance of payable to equipment suppliers	1,145,359	1,816,555	1,405,931
Less: Ending balance of payable to equipment suppliers	(1,816,555)	(1,405,931)	(1,196,181)
Less: Ending balance of payable to equipment suppliers – related parties	—	—	(58,549)
Less: Transfer from other non-current assets	—	(629,737)	(305,791)
Cash paid during the year	5,881,506	4,699,369	3,073,881

Investments accounted for using equity method - Summarized Financial Information for Investment in Material Associates (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of associates [line items]
Other comprehensive income (loss), net of income tax	$ (170,976)	$ (5,584)	$ 184,329	$ 84,203
Total comprehensive income (loss) for the year	1,796,589	$ 58,674	3,624,026	5,021,470
Individually Immaterial Associates [member]
Disclosure of associates [line items]
Profit for the year from continuing operations	1,714		453,715	625,733
Other comprehensive income (loss), net of income tax	12,993		(28,254)	28,843
Total comprehensive income (loss) for the year	$ 14,707		$ 425,461	$ 654,576

- Definition

The amount of change in equity resulting from transactions and other events, other than those changes resulting from transactions with owners in their capacity as owners.

+ References + Details

Non-current financial assets at fair value through other comprehensive income (Tables)

12 Months Ended

Dec. 31, 2023

Non-current financial assets at fair value through other comprehensive income [abstract]

Summary of Non-current Financial Assets at Fair Value Through Other Comprehensive Income


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Designation of equity instruments
Foreign unlisted stocks	38,534	38,534
Valuation adjustment	299,568	81,783
	338,102	120,317

Summary Amounts recognized in other comprehensive income in relation to the financial assets at fair value through other comprehensive income

Employee benefit expenses

12 Months Ended

Dec. 31, 2023

Employee benefit expenses [Abstract]

Employee benefit expenses

30.

Employee benefit expenses


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Salaries	5,632,219	5,302,234	4,741,380
Directors’ remuneration	40,164	28,621	23,980
Labor and health insurance	424,901	449,223	432,568
Pension	200,014	205,671	195,359
Other personnel expenses	460,590	480,554	442,781
	6,757,888	6,466,303	5,836,068

In accordance with the Company’s Articles of Incorporation, employees’ compensation is based on the current year’s earnings, which should first be used to cover accumulated deficits, if any, and then 10% of the remaining balance distributed as employees’ compensation, including distributions to certain qualifying employees in affiliate companies, and no more than 0.5% as directors’ remuneration. Subject to the Board of Directors’ approval, employees’ compensation may be made by way of cash or share issuance. Distribution of employees’ compensation and directors’ remuneration shall be presented and reported in the subsequent shareholders’ meeting.

Based on profit as of the end of reporting period, for the years ended December 31, 2021, 2022 and 2023, the employees’ compensation were accrued at NT$673,387 thousand, NT$447,303 thousand and 250,181 thousand, respectively; the directors’ remuneration were accrued at NT$25,690 thousand, NT$11,182 thousand and NT$6,255 thousand, respectively.

For the year of 2022, employees’ compensation and directors’ remuneration recognized were consistent with the amounts resolved in the Board of Directors’ meeting.

Non-current Financial Assets at Fair Value Through Other Comprehensive Income - Additional Information (Detail) - TWD ($) shares in Thousands	1 Months Ended
	Apr. 30, 2023	Dec. 31, 2023
Non-current financial assets at fair value through other comprehensive income [Line Items]
Financial assets at fair value through other comprehensive income were pledged		$ 0
Daypower Energy [member] \| Ordinary shares [member]
Non-current financial assets at fair value through other comprehensive income [Line Items]
Number of shares acquired	1,000
Amount of shares acquired value	$ 12,500,000
Acquired Percentage Of Shareholdings	10.00%

Summary of material accounting policies

12 Months Ended

Dec. 31, 2023

Summary Of Material Accounting Policies [Abstract]

Summary of material accounting policies

The principal accounting policies applied in the preparation of these accompanying consolidated financial statements are set out below. These policies have been consistently applied during the reported periods, unless otherwise stated.

Statement of compliance

The consolidated financial statements of the Group have been prepared in accordance with IFRSs as issued by the IASB.

Basis of preparation

(a)

Except for the following items, the consolidated financial statements have been prepared under the historical cost convention:

Financial assets at fair value through profit or loss (including derivative instruments).

ii)

Financial assets at fair value through other comprehensive income.

iii)

Defined benefit liabilities were recognized based on the net amount of pension fund assets less the present value of benefit obligation.

(b)

The preparation of the consolidated financial statements in conformity with IFRSs requires the use of certain critical accounting estimates. It also requires management to exercise its judgment in the process of applying the Group’s accounting policies. The areas involving a higher degree of judgment or complexity, or areas where assumptions and estimates are significant to the consolidated financial statements are disclosed in Note 4 dd).

(c)

These consolidated financial statements are presented in New Taiwan dollars (“NT$”), which is the Company’s functional currency.

Basis of consolidation

(a)

Basis for preparation of consolidated financial statements:

All subsidiaries are included in the Group’s consolidated financial statements. Subsidiaries are all entities controlled by the Group. The Group controls an entity when the Group is exposed, or has rights, to variable returns from its involvement with the entity and has the ability to affect those returns through its power over the entity. Consolidation of subsidiaries begins from the date the Group obtains control of the subsidiaries and ceases when the Group loses control of the subsidiaries.

ii)

Transactions, balances and unrealized gains or losses on transactions between companies within the Group are eliminated. Accounting policies of subsidiaries have been adjusted where necessary to ensure consistency with the policies adopted by the Group.

iii)

Profit or loss and each component of other comprehensive income are attributed to the owners of the parent and to the non-controlling interests. Total comprehensive income is attributed to the owners of the parent and to the non-controlling interests even if this results in a deficit balance in the non-controlling interests.

iv)

Changes in a parent’s ownership interest in a subsidiary that do not result in the parent losing control of the subsidiary (transactions with non-controlling interests) are accounted for as equity transactions, i.e. transactions with owners in their capacity as owners. Any difference between the amount by which the non-controlling interests are adjusted and the fair value of the consideration paid or received is recognized directly in equity.

When the Group loses control of a subsidiary, the Group remeasures any investment retained in the former subsidiary at its fair value. That fair value is regarded as the fair value on initial recognition of a financial asset or the cost on initial recognition of the associate or joint venture. Any difference between fair value and carrying amount is recognized in profit or loss. All amounts previously recognized in other comprehensive income in relation to the subsidiary are reclassified to profit or loss on the same basis as would be required if the related assets or liabilities were disposed of. That is, when the Group loses control of a subsidiary, all gains or losses previously recognized in other comprehensive income in relation to the subsidiary should be reclassified from equity to profit or loss, if such gains or losses would be reclassified to profit or loss when the related assets or liabilities are disposed of.

(b)

Subsidiaries included in the consolidated financial statements:


				Percentage of Ownership (%)
				December 31,
Name of investor	Name of investee	Main business	Location	2022	2023
The Company	ChipMOS U.S.A., Inc. (“ChipMOS USA”)	Marketing of semiconductors and electronic related products	San Jose, USA	100	100
The Company	ChipMOS TECHNOLOGIES (BVI) LTD. (“ChipMOS BVI”)	Holding company	British Virgin Islands	100	100
ChipMOS BVI	ChipMOS SEMICONDUCTORS (Shanghai) LTD. (“ChipMOS Shanghai”)	Marketing of semiconductors and electronic related products	Shanghai, People’s Republic of China (“PRC”)	100	100

(c)

Subsidiaries not included in the consolidated financial statements: None.

(d)

Adjustments for subsidiaries with different statements of financial position dates: Not applicable.

(e)

No significant restrictions on the ability of subsidiaries to transfer funds to parent company.

(f)

Subsidiaries that have non-controlling interests that are material to the Group: None.

Foreign currency translation

Items included in the financial statements of each of the Group’s entities are measured using the currency of the primary economic environment in which the entity operates (the “functional currency”). The consolidated financial statements are presented in NT$, which is the Company’s functional currency and the Group’s presentation currency.

(a)

Foreign currency transactions and balances

Foreign currency transactions are translated into the functional currency using the exchange rates on the trade date or measurement date. Therefore, foreign exchange differences resulting from the settlement of such transactions are recognized in profit or loss in the period in which they arise.

ii)

Monetary assets and liabilities denominated in foreign currencies at the period end are re-translated at the exchange rates prevailing at the statements of financial position date. Exchange differences arising upon re-translation are recognized in profit or loss on the statements of financial position date.

iii)

Non-monetary assets and liabilities denominated in foreign currencies held at fair value through profit or loss are re-translated at the exchange rates prevailing at the statements of financial position date; their exchange differences are recognized in profit or loss. Non-monetary assets and liabilities denominated in foreign currencies held at fair value through other comprehensive income are re-translated at the exchange rates prevailing at the statements of financial position date; their exchange differences are recognized in other comprehensive income. However, non-monetary assets and liabilities denominated in foreign currencies that are not measured at fair value are translated using the historical exchange rates at the initial dates of the transactions.

iv)

All foreign exchange differences are presented in the statement of comprehensive income under “Other gains and losses” by the nature of transactions.

(b)

Translation of foreign operations

The operating results and financial position of all the group entities, associates that have different functional currency and presentation currency are translated into the presentation currency as follows:

Assets and liabilities for each statements of financial position are translated at the exchange rates prevailing at the statements of financial position date;

ii)

Income and expenses for each statement of comprehensive income are translated at average exchange rates of that period; and

iii)

All exchange differences are recognized in other comprehensive income.

Classification of current and non-current assets and liabilities

(a)

Assets that meet one of the following criteria are classified as current assets:

Assets arising from operating activities that are expected to be realized, or are intended to be sold or consumed within the normal operating cycle;

ii)

Assets held mainly for trading purposes;

iii)

Assets that are expected to be realized within 12 months from the statements of financial position date;

iv)

Cash and cash equivalents, excluding restricted cash and cash equivalents and those that are to be exchanged or used to pay off liabilities more than 12 months after the statements of financial position date.

All assets that do not meet the above criteria are classified as non-current assets.

(b)

Liabilities that meet one of the following criteria are classified as current liabilities:

Liabilities that are expected to be settled within the normal operating cycle;

ii)

Liabilities arising mainly from trading activities;

iii)

Liabilities that are to be settled within 12 months from the statements of financial position date;

iv)

Liabilities for which the repayment date cannot be unconditionally extended to more than 12 months after the statements of financial position date. Liabilities bearing terms that could, at the option of the counterparty, result in its settlement by the issue of equity instruments do not affect its classification.

All liabilities that do not meet the above criteria are classified as non-current liabilities.

Cash equivalents

Cash equivalents refer to short-term, highly liquid investments that are readily convertible to known amounts of cash and are subject to an insignificant risk of changes in value (including time deposits with less than 3 months contract period). Time deposits that meet the above definition and are held for the purpose of meeting short-term cash commitments in operations are classified as cash equivalents.

Financial assets at fair value through profit or loss

(a)

Financial assets at fair value through profit or loss are financial assets that are not measured at amortized cost or fair value through other comprehensive income.

(b)

On a regular way purchase or sale basis, financial assets at fair value through profit or loss are recognized and derecognized using settlement date accounting.

(c)

At initial recognition, the Group measures the financial assets at fair value and recognizes the transaction costs in profit or loss. The Group subsequently measures the financial assets at fair value, and recognizes the gain or loss in profit or loss.

(d)

The Group recognizes the dividend income when the right to receive such payment is confirmed, inflow of the future economic benefits associated with the dividend is probable to the Group and the amount of the dividend can be measured reliably.

Financial assets at fair value through other comprehensive income

(a)

Financial assets at fair value through other comprehensive income comprise equity instruments which are not held for trading, and for which the Group has made an irrevocable election at initial recognition to recognize changes in fair value in other comprehensive income.

(b)

On a regular way purchase or sale basis, financial assets at fair value through other comprehensive income are recognized and derecognized using settlement date accounting.

(c)

At initial recognition, the Group measures the financial assets at fair value plus transaction costs. The Group subsequently measures the financial assets at fair value:

The changes in fair value of equity instruments that were recognized in other comprehensive income are reclassified to retained earnings and are not reclassified to profit or loss following the derecognition of the investment. Dividends are recognized as income when the right to receive such payment is confirmed, inflow of the future economic benefits associated with the dividend is probable to the Group and the amount of the dividend can be measured reliably.

Financial assets at amortized cost

(a)

Financial assets at amortized cost are those that meet all of the following criteria:

The objective of the Group’s business model is achieved by collecting contractual cash flows.

ii)

The financial assets’ contractual cash flows represent solely payments of principal and interest.

(b)

The Group’s time deposits which do not fall under cash equivalents are those with a short maturity period and are measured at initial investment amount as the effect of discounting is immaterial.

Accounts receivable

(a)

Accounts receivable entitle the Group a legal right to receive consideration in exchange for transferred goods or rendered services.

(b)

The short-term accounts receivable without bearing interest are subsequently measured at initial invoice amount as the effect of discounting is immaterial.

Impairment of financial assets

For financial assets at amortized cost, at each reporting date, the Group recognizes the impairment provision for 12 months expected credit losses if there has not been a significant increase in credit risk since initial recognition or recognizes the impairment provision for the lifetime expected credit losses if such credit risk has increased since initial recognition after taking into consideration all reasonable and verifiable information that includes forecasts. On the other hand, for accounts receivable or contract assets that do not contain a significant financing component, the Group recognizes the impairment provision for lifetime expected credit losses.

Derecognition of financial assets

The Group derecognizes a financial asset when the contractual rights to receive the cash flows from the financial asset have expired.

Inventories

Inventories are initially recorded at standard costs. Cost is determined on a weighted-average cost basis. At the end of reporting period, the differences between actual costs and standard costs were allocated to inventories and cost of revenue based on an appropriate rate. Allocation of fixed production overheads is based on the normal operating capacity of the production facilities. Costs associated with underutilized capacity are expensed in the period that the cost occurs.

Inventories are valued at the lower of cost and net realizable value. Net realizable value is the estimated selling price in the ordinary course of business less the estimated costs of completion and the estimated costs necessary to make the sale. The item by item approach is used in raw materials. The amount of any write-down of inventories to net realizable value and all losses of inventories are recognized as an expense in the period the write-down or loss occurs.

Non-current assets held for sale

Non-current assets are classified as assets held for sale when their carrying amount is to be recovered principally through a sale transaction rather than through continuing use, and a sale is considered highly probable. They are stated at the lower of carrying amount and fair value less costs to sell.

Investments accounted for using equity method – associates

(a)

Associates are all entities over which the Group has significant influence but not control. In general, it is presumed that the investor has significant influence, if an investor holds, directly or indirectly 20 percent or more of the voting power of the investee. Investments in associates are accounted for using the equity method and are initially recognized at cost.

(b)

The Group’s share of its associates’ post-acquisition profits or losses is recognized in profit or loss, and its share of post-acquisition movements in other comprehensive income is recognized in other comprehensive income. When the Group’s share of losses in an associate equals or exceeds its interests in the associate, including any other unsecured receivables, the Group does not recognize further losses, unless it has incurred legal or constructive obligations or made payments on behalf of the associate.

(c)

When changes in an associate’s equity that are not recognized in profit or loss or other comprehensive income of the associate and such changes not affecting the Group’s ownership percentage of the associate, the Group recognizes the Group’s share of change in equity of the associate in “Capital surplus” in proportion to its ownership.

(d)

Unrealized gains on transactions between the Group and its associates are eliminated to the extent of the Group’s interests in the associates. Unrealized losses are also eliminated unless the transaction provides evidence of an impairment of the asset transferred. Accounting policies of associates have been adjusted where necessary to ensure consistency with the policies adopted by the Group.

(e)

In the case where an associate issues new shares and the Group does not subscribe or proportionately acquire the new shares, which results in a change in the Group’s ownership percentage of the associate while maintaining significant influence on the associate, then the Group will treat the transaction as deemed disposal and reclassify to profit or loss the proportion of the gain or loss previously recognized in other comprehensive income relating to that reduction in ownership interest where appropriate.

(f)

When the Group disposes of its investment in an associate, if it loses significant influence on this associate, the amounts previously recognized in other comprehensive income in relation to the associate are reclassified to profit or loss, on the same basis as would be required if the relevant assets or liabilities were disposed of. If it still retains significant influence on this associate, then the amounts previously recognized in other comprehensive income in relation to the associate are reclassified to profit or loss proportionately in accordance with the aforementioned approach.

Property, plant and equipment

(a)

Property, plant and equipment are initially recorded at cost. Borrowing costs incurred during the construction period are capitalized.

(b)

Subsequent costs are included in the asset’s carrying amount or recognized as a separate asset, as appropriate, only when it is probable that future economic benefits associated with the item will flow to the Group and the cost of the item can be measured reliably. The carrying amount of the replaced part is derecognized. All other repairs and maintenance are charged to profit or loss during the financial period in which they are incurred.

(c)

Land is not depreciated. Other property, plant and equipment apply cost model and are depreciated using the straight-line method to allocate their cost over their estimated useful lives. Each part of an item of property, plant and equipment with a cost that is significant in relation to the total cost of the item must be depreciated separately.

(d)

The assets’ residual values, useful lives and depreciation methods are reviewed, and adjusted if appropriate, at each financial year-end. If expectations for the assets’ residual values and useful lives differ from previous estimates or the patterns of consumption of the assets’ future economic benefits embodied in the assets have changed significantly, any change is accounted for as a change in estimate under IAS 8, “Accounting Policies, Change in Accounting Estimates and Errors”, from the date of the change. The estimated useful lives of property, plant and equipment are as follows:


Buildings		1 to 51 years
Machinery and equipment		1 to 20 years
Tools		1 to 4 years
Others		1 to 7 years

Leasing arrangements (lessee) – right-of-use assets / lease liabilities

(a)

Leases are recognized as a right-of-use asset and a corresponding lease liability at the date at which the leased asset is available for use by the Group. For short-term leases or leases of low value assets, lease payments are recognized as an expense on a straight-line basis over the lease term.

(b)

Lease liabilities include the net present value of the remaining lease payments at the commencement date, discounted using the incremental borrowing interest rate.

Lease payments are comprised of the following:

Fixed payments, less any lease incentives receivable;

ii)

The exercise price of a purchase option, if the lessee is reasonably certain to exercise that option.

The Group subsequently measures the lease liability at amortized cost using the interest method and recognizes interest expense over the lease term. The lease liability is remeasured and the amount of remeasurement is recognized as an adjustment to the right-of-use asset when there are changes in the lease term or lease payments and such changes do not arise from contract modifications.

(c)

At the commencement date, the right-of-use asset is stated at the amount of the initial measurement of lease liability. The right-of-use asset is measured subsequently using the cost model and is depreciated from the commencement date to the earlier of the end of the asset’s useful life or the end of the lease term. When the lease liability is remeasured, the amount of remeasurement is recognized as an adjustment to the right-of-use asset.

Impairment of non-financial assets

The Group assesses at each statements of financial position date the recoverable amounts of those assets where there is an indication that they are impaired. An impairment loss is recognized for the amount by which the asset’s carrying amount exceeds its recoverable amount. The recoverable amount is the higher of an asset’s fair value less costs to sell or value in use. When the circumstances or reasons for recognizing impairment loss for an asset in prior years no longer exist or diminish, the impairment loss is reversed. The increased carrying amount due to reversal should not be more than what the depreciated or amortized historical cost would have been if the impairment had not been recognized.

Loans

Loans comprise long-term and short-term bank loans. Loans are recognized initially at fair value, net of transaction costs incurred. Loans are subsequently stated at amortized cost; any difference between the proceeds (net of transaction costs) and the redemption value is recognized as interest expense in profit or loss over the period of the loans using the effective interest method.

Accounts and notes payable

(a)

Accounts payable are liabilities for purchases of raw materials, goods or services and notes payable are those resulting from operating and non-operating activities.

(b)

The short-term accounts and notes payable without bearing interest are subsequently measured at initial invoice amount as the effect of discounting is immaterial.

Derecognition of financial liabilities

A financial liability is derecognized when the obligation specified in the contract is either discharged or cancelled or expires.

Provisions for deficiency compensation

Provisions are recognized when the Group has a present legal or constructive obligation as a result of past events, and it is probable that an outflow of economic resources will be required to settle the obligation and the amount of the obligation can be reliably estimated. Provisions are measured at the present value of the expenditures expected to be required to settle the obligation on the statements of financial position date, which is discounted using a pre-tax discount rate that reflects the current market assessments of the time value of money and the risks specific to the obligation. When discounting is used, the increase in the provision arising from the passage of time is recognized as interest expense. Provisions are not recognized for future operating losses.

Employee benefits

(a)

Short-term employee benefits

Short-term employee benefits are measured at the undiscounted amount of the benefits expected to be paid in respect of service rendered by employees and should be recognized as expenses when the employees render service.

(b)

Pensions

Defined contribution plans

For defined contribution plans, the contributions are recognized as pension expenses when they are due on an accrual basis. Prepaid contributions are recognized as an asset to the extent of a cash refund or a reduction in future payments.

ii)

Defined benefit plans

Net obligation under a defined benefit plan is defined as the present value of an amount of pension benefits that employees will receive on retirement for their services with the Group in the current period or prior periods. The liability recognized in the statements of financial position in respect of defined benefit pension plans is the present value of the defined benefit obligation at the statements of financial position date less the fair value of plan assets. The net defined benefit obligation is calculated annually by independent actuaries using the projected unit credit method. The discount rate is determined by using the interest rates of government bonds that are denominated in the currency in which the benefits will be paid, and that have terms to maturity approximating to the terms of the related pension liability.

Remeasurements arising on defined benefit plans are recognized in other comprehensive income in the period in which they arise and are recorded as retained earnings.

Past service costs are recognized immediately in profit or loss.

(c)

Termination benefits

Termination benefits are employee benefits provided in exchange for the termination of employment as a result from either the Group’s decision to terminate an employee’s employment before the normal retirement date, or an employee’s decision to accept an offer of redundancy benefits in exchange for the termination of employment. The Group recognizes an expense as it can no longer withdraw an offer of termination benefits, or it recognizes related restructuring costs, whichever is earlier. Benefits that are expected to be due more than 12 months after statements of financial position date shall be discounted to their present value.

(d)

Employees’ compensation and directors’ remuneration

Employees’ compensation and directors’ remuneration are recognized as expenses and liabilities, provided that such recognition is required under legal obligation or constructive obligation and those amounts can be reliably estimated. Any difference between the resolved amounts and the subsequently actual distributed amounts is accounted for as changes in estimates. If employee compensation is paid by shares, the Company calculates the number of shares based on the closing price at the previous day of the board meeting resolution.

Income tax

(a)

The income tax expense for the period comprises current and deferred tax. Income tax is recognized in profit or loss, except to the extent that it relates to items recognized in other comprehensive income or items recognized directly in equity, in which cases the income tax is recognized in other comprehensive income or equity.

(b)

The current income tax expense is calculated on the basis of the tax laws enacted or substantively enacted at the statements of financial position date in the countries where the Group and its subsidiaries operate and generate taxable income. Management periodically evaluates positions taken in tax returns with respect to situations in accordance with applicable tax regulations. It establishes provisions where appropriate based on the amounts expected to be paid to the tax authorities. An additional income tax is levied on the unappropriated retained earnings and is recorded as income tax expense in the year the profit generated.

(c)

Deferred tax is recognized, using the balance sheet liability method, on temporary differences arising between the tax bases of assets and liabilities and their carrying amounts in the consolidated statements of financial position. However, the deferred tax is not accounted for if it arises from initial recognition of an asset or liability in a transaction other than a business combination that at the time of the transaction affects neither accounting nor taxable profit or loss. Deferred tax is provided on temporary differences arising on investments in subsidiaries and associates, except where the timing of the reversal of the temporary difference is controlled by the Group and it is probable that the temporary difference will not reverse in the foreseeable future. Deferred tax is determined using tax rates (and laws) that have been enacted or substantially enacted at the statements of financial position date and are expected to apply when the related deferred tax asset is realized or the deferred tax liability is settled.

(d)

Deferred tax assets are recognized only to the extent that it is probable that future taxable profit will be available against which the temporary differences can be utilized. At each statements of financial position date, unrecognized and recognized deferred tax assets are reassessed.

(e)

A deferred tax asset shall be recognized for the carryforward of unused tax credits resulting from equity investments to the extent that it is possible that future taxable profit will be available against which the unused tax credits can be utilized.

(f)

If a change in tax rate is enacted or substantively enacted, the Group recognizes the effect of the change immediately in the period in which the change occurs. The effect of the change on items recognized outside profit or loss is recognized in other comprehensive income or equity while the effect of the change on items recognized in profit or loss is recognized in profit or loss.

Capital stock

(a)

Ordinary shares are classified as equity. Incremental costs directly attributable to the issue of new shares in net proceeds of tax are shown in equity as a deduction.

(b)

Where the Company repurchases the Company’s shares that have been issued, the consideration paid, including any directly attributable incremental costs (net of income taxes) is deducted from equity attributable to the Company’s equity holders. Where such shares are subsequently reissued, the difference between their book value and any consideration received, net of any directly attributable incremental transaction costs and the related income tax effects, is included in equity attributable to the Company’s equity holders.

Dividends

Dividends are recorded in the Company’s financial statements in the period in which they are resolved by the Company’s shareholders. Cash dividends are recorded as liabilities; stock dividends are recorded as stock dividends to be distributed and are reclassified to ordinary shares on the effective date of new shares issuance.

aa)

Revenue recognition

(a)

The Group is primarily engaged in the customized assembly and testing services of high-integration and high-precision integrated circuits based on customer’s specification demand to create or enhance the product. When providing assembly and testing services, the Group considers:

Customer controls the provided raw materials and the Group receives the instruction from the customer on providing assembly and testing services and subsequent treatments.

ii)

The Group provides assembly and testing services to create or enhance an asset which is solely provided and controlled by the customer. The Group has no right to transfer the asset for another use.

As the asset ownership belongs to the customer, who bears the significant risk and rewards and rights on the use of the asset, the Group recognizes assembly and testing service revenue based on the progress towards completion of performance obligation during the service period.

(b)

The progress towards completion on Assembly services, services for Display panel driver semiconductor assembly and testing (“LCDD”) and Bumping are measured by the actual input costs relative to estimate total expected input costs. The progress towards completion on testing services is measured by the actual incurred testing volume. The Group provides assembly and testing services based on customer’s specification, thus, the input costs incurred to assembly and testing volume completed in testing services are not linear over the duration of these services. Customer payment on assembly and testing services is based on predetermined payment schedule. A contract asset is recognized when the Group provides services in excess of customer’s payment.

bb)

Government grants

Government grants are recognized at their fair value only when there is reasonable assurance that the Group will comply with any conditions attached to the grants will be received. Government grants are recognized in profit or loss on a systematic basis over the periods in which the Group recognizes expenses for the related costs for which the grants are intended to compensate.

Government grants related to property, plant and equipment are recognized as non-current liabilities and are amortized to profit or loss over the estimated useful lives of the related assets using straight-line method.

cc)

Operating segments

Operating segments are reported in a manner consistent with the internal reporting provided to the chief operating decision maker. The Group’s chief operating decision maker, who is responsible for allocating resources and assessing performance of the operating segments, has been identified as the Chairman of the Board of Directors that makes strategic decisions.

dd)

Critical accounting judgments, estimates and key sources of assumption uncertainty

The preparation of the accompanying consolidated financial statements requires management to make critical judgments in applying the Group’s accounting policies and make critical assumptions and estimates concerning future events. Assumptions and estimates may differ from the actual results and are continually evaluated and adjusted based on historical experience and other factors. Such assumptions and estimates have a significant risk of causing a material adjustment to the carrying amounts of assets and liabilities within the next financial year; and the related information is addressed below:

Critical accounting estimates and assumptions – Revenue recognition

The Group recognizes revenue from services for Assembly, LCDD and Bumping based on the progress towards completion of performance obligation during the service period. The Group estimates total expected input costs based on historical experience and measures the progress towards completion by the actual input costs relative to the total expected input costs.

Segment Information - Schedule of Information on Products and Services (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of products and services [line items]
Net revenue	$ 21,356,228	$ 697,460	$ 23,517,064	$ 27,400,035
Percentage of total revenue	100.00%	100.00%	100.00%	100.00%
Testing [member]
Disclosure of products and services [line items]
Net revenue	$ 4,394,726		$ 5,243,997	$ 5,899,600
Percentage of total revenue	20.00%	20.00%	22.00%	22.00%
Assembly [member]
Disclosure of products and services [line items]
Net revenue	$ 4,629,430		$ 6,705,898	$ 7,963,714
Percentage of total revenue	22.00%	22.00%	29.00%	29.00%
LCDD [member]
Disclosure of products and services [line items]
Net revenue	$ 7,821,640		$ 7,288,642	$ 8,211,099
Percentage of total revenue	37.00%	37.00%	31.00%	30.00%
Bumping [member]
Disclosure of products and services [line items]
Net revenue	$ 4,510,432		$ 4,278,527	$ 5,325,622
Percentage of total revenue	21.00%	21.00%	18.00%	19.00%

- Definition

+ References

+ Details

Inventories - Cost of Inventories Recognized as an Expense (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Analysis of income and expense [abstract]
Cost of revenue	$ 17,723,687		$ 18,611,515	$ 20,103,735
Loss on abandonment	2,483		9,448	552
Allowance for (reversal of) inventory valuation and obsolescence loss	80,633		(15,956)	41,770
Cost of revenue	$ 17,806,803	$ 581,542	$ 18,605,007	$ 20,146,057

Financial Assets at Fair Value Through Profit or Loss - Summary of Amounts recognized in Profit or Loss in Relation to Financial Assets at Fair Value Through Profit or Loss (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Financial Assets At Fair Value Through Profit Or Loss [line items]
Financial assets mandatorily measured at fair value through profit or loss	$ 39,254	$ 1,282	$ (69,404)	$ 15,262
Foreign partnership interests [member]
Financial Assets At Fair Value Through Profit Or Loss [line items]
Financial assets mandatorily measured at fair value through profit or loss				(941)
Beneficiary certificates [member]
Financial Assets At Fair Value Through Profit Or Loss [line items]
Financial assets mandatorily measured at fair value through profit or loss	17,253		5,807	2,530
Listed stocks [member]
Financial Assets At Fair Value Through Profit Or Loss [line items]
Financial assets mandatorily measured at fair value through profit or loss	$ 22,001		$ (75,211)	$ 13,673

Income tax expense

12 Months Ended

Dec. 31, 2023

Income tax expense [abstract]

Income tax expense

31.

Income tax expense

(a)

Components of income tax expense:


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Current income tax:
Current income tax on profits for the period	1,109,752	771,378	426,878
Income tax on unappropriated retained earnings	227,467	159,744	85,607
Prior year income tax overestimation	(184,284)	(255,935)	(182,778)
Total current income tax	1,152,935	675,187	329,707
Deferred income tax:
Relating to origination and reversal of temporary differences	(54,617)	(87,012)	(29,046)
Income tax expense	1,098,318	588,175	300,661

(b)

The income tax (charge)/credit relating to components of other comprehensive income are as follows:


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income	30,459	(12,559)	(51,638)
Remeasurement of defined benefit obligations	(2,999)	44,447	2,140
	27,460	31,888	(49,498)

Reconciliation of income tax expense and the accounting profit:


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Tax calculated based on profit before tax and statutory tax rate	1,207,605	804,086	451,676
Effects from adjustments based on regulation	(152,618)	(131,873)	(74,094)
Gain on investment in associates	—	11,923	19,228
Prior year income tax overestimation	(184,284)	(255,935)	(182,778)
Income tax on unappropriated retained earnings	227,467	159,744	85,607
Effect of different tax rates in countries in which the Group operates	148	230	1,022
Income tax expense	1,098,318	588,175	300,661

The amounts of deferred tax assets or liabilities resulting from temporary differences and investment tax credits are as follows:


	2021
	January 1	Recognized in profit or loss	Recognized in other comprehensive income	December 31
	NT$000	NT$000	NT$000	NT$000
Deferred tax assets
Loss on inventories	15,963	8,354	—	24,317
Property, plant and equipment	36,401	235	—	36,636
Provisions	2,678	171	—	2,849
Deferred revenue	21,144	(6,506)	—	14,638
Net defined benefit liability	98,921	(4,672)	2,999	97,248
Unrealized exchange losses	9,915	(7,754)	—	2,161
Others	669	2,080	—	2,749
Total	185,691	(8,092)	2,999	180,598
Deferred tax liabilities
Property, plant and equipment	(255,484)	62,797	—	(192,687)
Financial assets at fair value through other comprehensive income	(54,943)	—	(30,459)	(85,402)
Others	—	(88)	—	(88)
Total	(310,427)	62,709	(30,459)	(278,177)
Information presented on statements of financial position:
Deferred tax assets	185,691			180,598
Deferred tax liabilities	(310,427)			(278,177)


	2022
	January 1	Recognized in profit or loss	Recognized in other comprehensive income	December 31
	NT$000	NT$000	NT$000	NT$000
Deferred tax assets
Loss on inventories	24,317	(3,191)	—	21,126
Property, plant and equipment	36,636	2,258	—	38,894
Provisions	2,849	10,010	—	12,859
Deferred revenue	14,638	(6,506)	—	8,132
Net defined benefit liability	97,248	(4,368)	(44,447)	48,433
Unrealized exchange losses	2,161	22,056	—	24,217
Others	2,749	2,876	—	5,625
Total	180,598	23,135	(44,447)	159,286
Deferred tax liabilities
Property, plant and equipment	(192,687)	75,713	—	(116,974)
Financial assets at fair value through other comprehensive income	(85,402)	—	12,559	(72,843)
Gain on investment in associates	—	(11,923)	—	(11,923)
Others	(88)	87	—	(1)
Total	(278,177)	63,877	12,559	(201,741)
Information presented on statements of financial position:
Deferred tax assets	180,598			159,286
Deferred tax liabilities	(278,177)			(201,741)


	2023
	January 1	Recognized in profit or loss	Recognized in other comprehensive income	December 31
	NT$000	NT$000	NT$000	NT$000
Deferred tax assets
Loss on inventories	21,126	16,127	—	37,253
Property, plant and equipment	38,894	1,847	—	40,741
Provisions	12,859	1,518	—	14,377
Deferred revenue	8,132	(6,506)	—	1,626
Net defined benefit liability	48,433	(4,236)	(2,140)	42,057
Unrealized exchange losses	24,217	(6,032)	—	18,185
Others	5,625	3,418	—	9,043
Total	159,286	6,136	(2,140)	163,282
Deferred tax liabilities
Property, plant and equipment	(116,974)	42,142	—	(74,832)
Financial assets at fair value through other comprehensive income	(72,843)	—	51,638	(21,205)
Gain on investment in associates	(11,923)	(19,228)	—	(31,151)
Others	(1)	(4)	—	(5)
Total	(201,741)	22,910	51,638	(127,193)
Information presented on statements of financial position:
Deferred tax assets	159,286			163,282
Deferred tax liabilities	(201,741)			(127,193)

The Company has not recognized taxable temporary differences associated with investments as deferred tax liabilities. As of December 31, 2022 and 2023, the amounts of temporary differences not recognized as deferred tax liabilities were NT$1,080,272 thousand and NT$1,245,171 thousand, respectively.

The Company’s income tax returns through 2021 have been assessed and approved by the Tax Authority.

Segment information (Tables)

12 Months Ended

Dec. 31, 2023

Disclosure of operating segments [abstract]

Financial Segment Information for Operating Segments

The segment information provided to the chief operating decision maker for the reportable segments is as follows:


	Year ended December 31, 2021
	Testing	Assembly	LCDD	Bumping	Others	Elimination	Total
	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000
Revenue
External customers	5,899,600	7,963,714	8,211,099	5,325,622	—	—	27,400,035
Inter-segment	—	—	—	—	43,808	(43,808)	—
Total revenue	5,899,600	7,963,714	8,211,099	5,325,622	43,808	(43,808)	27,400,035
Operating profit (loss)	1,814,021	857,304	2,336,394	561,642	(6,987)	15	5,562,389
Depreciation expenses	(921,999)	(576,138)	(2,579,150)	(549,020)	(7,805)	—	(4,634,112)
Share of profit of associates	—	—	—	—	1,211,177	(585,444)	625,733
Interest income	—	—	—	—	9,980	—	9,980
Interest expense	—	—	—	—	(120,998)	—	(120,998)
Purchase of property, plant and equipment	1,841,359	1,553,475	2,748,697	408,751	420	—	6,552,702


	Year ended December 31, 2022
	Testing	Assembly	LCDD	Bumping	Others	Elimination	Total
	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000
Revenue
External customers	5,243,997	6,705,898	7,288,642	4,278,527	—	—	23,517,064
Inter-segment	—	—	—	—	50,600	(50,600)	—
Total revenue	5,243,997	6,705,898	7,288,642	4,278,527	50,600	(50,600)	23,517,064
Operating profit (loss)	1,253,477	(93,585)	1,795,741	268,159	(6,821)	(292)	3,216,679
Depreciation expenses	(1,042,455)	(694,835)	(2,505,297)	(500,863)	(8,452)	—	(4,751,902)
Share of profit of associates	—	—	—	—	884,555	(430,840)	453,715
Interest income	—	—	—	—	57,199	—	57,199
Interest expense	—	—	—	—	(142,439)	—	(142,439)
Purchase of property, plant and equipment	1,086,682	957,790	2,677,489	196,521	—	—	4,918,482


	Year ended December 31, 2023
	Testing	Assembly	LCDD	Bumping	Others	Elimination	Total
	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000
Revenue
External customers	4,394,726	4,629,430	7,821,640	4,510,432	—	—	21,356,228
Inter-segment	—	—	—	—	59,481	(59,481)	—
Total revenue	4,394,726	4,629,430	7,821,640	4,510,432	59,481	(59,481)	21,356,228
Operating profit (loss)	514,707	(1,180,481)	2,058,285	522,386	(6,194)	(251)	1,908,452
Depreciation expenses	(1,065,689)	(722,462)	(2,547,253)	(435,709)	(8,220)	—	(4,779,333)
Share of profit of associates	—	—	—	—	420,393	(200,502)	219,891
Interest income	—	—	—	—	193,189	—	193,189
Interest expense	—	—	—	—	(265,957)	—	(265,957)
Purchase of property, plant and equipment	749,158	568,289	1,756,590	152,908	1,526	—	3,228,471

Schedule of information on products and services

Information on products and services


	Year ended December 31,
	2021		2022		2023
	NT$000	%	NT$000	%	NT$000	%
Testing	5,899,600	22	5,243,997	22	4,394,726	20
Assembly	7,963,714	29	6,705,898	29	4,629,430	22
LCDD	8,211,099	30	7,288,642	31	7,821,640	37
Bumping	5,325,622	19	4,278,527	18	4,510,432	21
	27,400,035	100	23,517,064	100	21,356,228	100

Geographic Information of Revenue

Geographical information


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Revenue
ROC	21,608,567	18,671,142	17,287,574
Japan	1,768,460	1,989,805	1,176,163
PRC	1,899,362	1,970,943	1,729,908
Singapore	1,630,733	390,488	676,088
Others	492,913	494,686	486,495
	27,400,035	23,517,064	21,356,228


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Non-current assets
ROC	21,677,980	20,360,166
PRC	2,291	1,279
Others	576	6,122
	21,680,847	20,367,567

Net Revenue from Customers Representing at Least 10% of Total Revenue

The information on the major customers which constituted more than 10% of the Group’s total revenue for the years ended December 31, 2021, 2022 and 2023 is as follows:


	Year ended December 31,
	2021		2022		2023
	NT$000	%	NT$000	%	NT$000	%
Customers
Customer A	5,681,277	21	4,705,064	20	5,251,529	25
Customer B	2,484,611	9	1,868,583	8	2,834,188	13
Customer M	2,832,088	10	2,278,645	10	1,320,905	6

Income Tax Expense - Reconciliation of Income Tax Expense and Accounting Profit Before Income Tax (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Reconciliation of income tax expense and accounting profit before income tax [abstract]
Tax calculated based on profit before tax and statutory tax rate	$ 451,676		$ 804,086	$ 1,207,605
Effects from adjustments based on regulation	(74,094)		(131,873)	(152,618)
Gain on investment in associates	19,228		11,923
Prior year income tax overestimation	(182,778)		(255,935)	(184,284)
Income tax on unappropriated retained earnings	85,607		159,744	227,467
Effect of different tax rates in countries in which the Group operates	1,022		230	148
Income tax expense	$ 300,661	$ 9,819	$ 588,175	$ 1,098,318

- Definition

The aggregate amount included in the determination of profit (loss) for the period in respect of current tax and deferred tax. [Refer: Current tax expense (income); Deferred tax expense (income)]

+ References + Details

Supplemental Cash Flow Information - Partial Cash Paid for Investing Activities (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Supplemental cash flow information [line items]
Purchase of property, plant and equipment	$ 3,228,471		$ 4,918,482	$ 6,552,702
Add: Beginning balance of payable to equipment suppliers	1,405,931		1,816,555	1,145,359
Less: Ending balance of payable to equipment suppliers	(1,196,181)		(1,405,931)	(1,816,555)
Less: Transfer from other non-current assets	(305,791)		(629,737)
Cash paid during the year	3,073,881	$ 100,389	$ 4,699,369	$ 5,881,506
Related parties [member]
Supplemental cash flow information [line items]
Less: Ending balance of payable to equipment suppliers	$ (58,549)

Significant contingent liabilities and unrecognized contract commitments

12 Months Ended

Dec. 31, 2023

Capital commitments [abstract]

Significant contingent liabilities and unrecognized contract commitments

37.

Significant contingent liabilities and unrecognized contract commitments

A letter of guarantee was issued by the financial institutions to the Customs Administration of the Ministry of Finance for making payment of customs-duty deposits when importing. As of December 31, 2022 and 2023, the amounts guaranteed by the financial institutions were NT$135,600 thousand and NT$71,900 thousand, respectively.

Capital expenditures that are contracted for, but not provided for are as follows:


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Property, plant and equipment, net	1,703,841	1,940,740

Changes in liabilities from financing activities - Reconciliation of Liabilities Arising from Financing Activities (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	$ 14,909,803	$ 11,017,992	$ 8,625,730
Changes in cash flow from financing activities	613,558	3,544,027	2,094,370
Adjustment of right-of-use assets	419,625	292,464	255,179
Amortization of loan fees		10,026	7,646
Amortization of interest expense	55,369	45,294	35,067
Ending balance	15,998,355	14,909,803	11,017,992
Short-term bank loans [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance		731,751
Changes in cash flow from financing activities		(731,751)	731,751
Ending balance			731,751
Long-term bank loans (include the current portion) [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	13,967,801	9,413,365	7,733,565
Changes in cash flow from financing activities	907,306	4,513,672	1,652,332
Amortization of loan fees		10,026	7,646
Amortization of interest expense	36,612	30,738	19,822
Ending balance	14,911,719	13,967,801	9,413,365
Guarantee deposits [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	21,600	21,625	21,670
Changes in cash flow from financing activities	(365)	(25)	(45)
Ending balance	21,235	21,600	21,625
Lease liabilities [member]
Disclosure of reconciliation of liabilities arising from financing activities [line items]
Beginning balance	920,402	851,251	870,495
Changes in cash flow from financing activities	(293,383)	(237,869)	(289,668)
Adjustment of right-of-use assets	419,625	292,464	255,179
Amortization of interest expense	18,757	14,556	15,245
Ending balance	$ 1,065,401	$ 920,402	$ 851,251

Long-term Bank Loans - Additional Information (Detail) $ in Millions		33 Months Ended
	May 15, 2018 TWD ($) Bank	Sep. 30, 2022 TWD ($)
Maximum [Member]
Disclosure of detailed information about borrowings [Line Items]
Maturity of loan		ten years
Minimum [Member]
Disclosure of detailed information about borrowings [Line Items]
Maturity of loan		seven years
Syndicated loan [member]
Disclosure of detailed information about borrowings [Line Items]
Number of banks in syndicate \| Bank	11
Principal amount of loan	$ 12,000
Maturity of loan	five years
Government granted bank loans [Member]
Disclosure of detailed information about borrowings [Line Items]
Principal amount of loan		$ 23,730

Leasing arrangements - leasee - Additional Information (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Leasing arrangements lessee [line items]
Additions to right of use asset	$ 419,625	$ 308,550
Payments of lease liabilities	$ 351,063	$ 333,133	$ 448,290
Top of range [member]
Leasing arrangements lessee [line items]
Lease term	30 years
Top of range [member] \| Land [member]
Leasing arrangements lessee [line items]
Lease term	30 years
Top of range [member] \| Machinery and equipment [member]
Leasing arrangements lessee [line items]
Lease term	3 years
Bottom of range [member]
Leasing arrangements lessee [line items]
Lease term	2 years
Bottom of range [member] \| Land [member]
Leasing arrangements lessee [line items]
Lease term	10 years
Bottom of range [member] \| Machinery and equipment [member]
Leasing arrangements lessee [line items]
Lease term	2 years

Earnings per share

12 Months Ended

Dec. 31, 2023

Earnings per share [abstract]

Earnings per share

32.

Earnings per share


	Year ended December 31, 2021
	Amount after income tax	Weighted average number of ordinary shares outstanding	Earnings per share
Basic earnings per share	NT$000	In thousands	NT$
Profit attributable to equity holders of the Company	4,937,267	727,240	6.79
Diluted earnings per share
Assumed conversion of all dilutive potential ordinary shares:
Employees’ compensation		15,618
Profit attributable to equity holders of the Company	4,937,267	742,858	6.65


	Year ended December 31, 2022
	Amount after income tax	Weighted average number of ordinary shares outstanding	Earnings per share
Basic earnings per share	NT$000	In thousands	NT$
Profit attributable to equity holders of the Company	3,439,697	727,240	4.73
Diluted earnings per share
Assumed conversion of all dilutive potential ordinary shares:
Employees’ compensation		15,406
Profit attributable to equity holders of the Company	3,439,697	742,646	4.63


	Year ended December 31, 2023
	Amount after income tax	Weighted average number of ordinary shares outstanding	Earnings per share
Basic earnings per share	NT$000	In thousands	NT$
Profit attributable to equity holders of the Company	1,967,565	727,240	2.71
Diluted earnings per share
Assumed conversion of all dilutive potential ordinary shares:
Employees’ compensation		7,698
Profit attributable to equity holders of the Company	1,967,565	734,938	2.68

Application of new and revised International Financial Reporting Standards, International Accounting Standards, International Financial Reporting Interpretations Committee Interpretations and Standing Interpretations Committee Interpretations issued by the International Accounting Standards Board

12 Months Ended

Dec. 31, 2023

Disclosure of initial application of standards or interpretations [abstract]

Application of new and revised International Financial Reporting Standards ("IFRS"), International Accounting Standards ("IAS"), International Financial Reporting Interpretations Committee ("IFRIC") Interpretations and Standing Interpretations Committee ("SIC") Interpretations issued by the International Accounting Standards Board ("IASB"), (collectively, "IFRSs")

Application of new and revised IFRS® Accounting Standards, International Accounting Standards (“IAS”), International Financial Reporting Interpretations Committee (“IFRIC®”) Interpretations and Standing Interpretations Committee (“SIC®”) Interpretations issued by the International Accounting Standards Board (“IASB”), (collectively, “IFRSs”)

Amendments to IFRSs and the new interpretation that are mandatorily effective for the current year


New Standards, Interpretations and Amendments		Effective date issued by IASB
Amendments to IAS 1, “Disclosure of Accounting Policies”		January 1, 2023
Amendments to IAS 8, “Definition of Accounting Estimates”		January 1, 2023
Amendments to IAS 12, “Deferred Tax related to Assets and Liabilities arising from a Single Transaction”		January 1, 2023
Amendments to IAS 12, “International Tax Reform–Pillar Two Model Rules”		May 23, 2023
IFRS 17, “Insurance Contracts”		January 1, 2023
Amendments to IFRS 17, “Insurance Contracts”		January 1, 2023
Amendment to IFRS 17, “Initial Application of IFRS 17 and IFRS 9 – Comparative Information”		January 1, 2023

Based on the Group’s assessment, the above standards and interpretations have no significant impact on the Group’s financial position and financial performance.

New standards, interpretations and amendments in issue but not yet effective


New Standards, Interpretations and Amendments		Effective date issued by IASB
Amendments to IFRS 16, “Lease Liability in a Sale and Leaseback”		January 1, 2024
Amendments to IAS 1, “Classification of Liabilities as Current or Non-current”		January 1, 2024
Amendments to IAS 1, “Non-current Liabilities with Covenants”		January 1, 2024
Amendments to IAS 7 and IFRS 7, “Supplier Finance Arrangements”		January 1, 2024
Amendments to IFRS 10 and IAS 28, “Sale or Contribution of Assets between an Investor and its Associate or Joint Venture”		To be determined by IASB
Amendments to IAS 21, “Lack of Exchangeability”		January 1, 2025

Based on the Group’s assessment, the above standards and interpretations have no significant impact on the Group’s financial position and financial performance.

Earnings Per Share - Income and Share Data Used in Basic and Diluted EPS Computations (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($) $ / shares shares	Dec. 31, 2023 $ / shares	Dec. 31, 2022 TWD ($) $ / shares shares	Dec. 31, 2021 TWD ($) $ / shares shares
Basic earnings per share, amount after tax
Equity holders of the Company - Amount after tax \| $	$ 1,967,565		$ 3,439,697	$ 4,937,267
Diluted earnings per share, amount after tax
Equity holders of the Company - Amount after tax \| $	$ 1,967,565		$ 3,439,697	$ 4,937,267
Weighted average number of ordinary shares outstanding	727,240		727,240	727,240
Diluted earnings per share, weighted-average number of ordinary shares outstanding
Employees' compensation	7,698		15,406	15,618
Weighted average number of ordinary shares outstanding	734,938		742,646	742,858
Ordinary shares [member]
Basic earnings per share
Equity holders of the Company - Earnings per share \| (per share)	$ 2.71	$ 0.09	$ 4.73	$ 6.79
Diluted earnings per share
Diluted earnings (loss) per share \| (per share)	$ 2.68	$ 0.09	$ 4.63	$ 6.65

Financial Risk Management and Fair Values of Financial Instruments - Maturity Profile of Non-derivative Financial Liabilities Based on Contracted Undiscounted Payments (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Long-term bank loans	$ 15,580,584	$ 14,643,068
Lease liabilities	1,257,694	1,118,787
Guarantee deposits	21,235	21,600
Total	16,859,513	15,783,455
Within 1 year [member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Long-term bank loans	2,469,744	1,699,165
Lease liabilities	267,759	174,460
Total	2,737,503	1,873,625
1 to 3 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Long-term bank loans	7,506,844	5,675,288
Lease liabilities	250,104	182,767
Total	7,756,948	5,858,055
3 to 5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Long-term bank loans	4,273,199	5,354,335
Lease liabilities	57,856	57,057
Total	4,331,055	5,411,392
Over 5 years [member]
Disclosure of maturity analysis for non-derivative financial liabilities [Line Items]
Long-term bank loans	1,330,797	1,914,280
Lease liabilities	681,975	704,503
Guarantee deposits	21,235	21,600
Total	$ 2,034,007	$ 2,640,383

Consolidated Statements of Changes in Equity $ in Thousands, $ in Thousands	TWD ($)	USD ($)	Capital stock [member] TWD ($)	Capital surplus [member] TWD ($)	Legal reserve [member] TWD ($)	Special reserve [member] TWD ($)	Unappropriated retained earnings [member] TWD ($)	Financial statements translation differences of foreign operations [member] TWD ($)	Unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income [member] TWD ($)	Equity directly related to non-current assets held for sale [member] TWD ($)
Beginning Balance at Dec. 31, 2020	$ 20,715,839		$ 7,272,401	$ 6,050,787	$ 1,837,894	$ 19,802	$ 5,401,569	$ (61,330)	$ 194,716
Profit for the year	4,937,267						4,937,267
Other comprehensive income (loss)	84,203						(4,251)	(24,695)	113,149
Total comprehensive income (loss) for the year	5,021,470						4,933,016	(24,695)	113,149
Appropriation of prior year's earnings:
Legal reserve					232,611		(232,611)
Special reserve						$ (19,802)	19,802
Cash dividends	(1,599,928)						(1,599,928)
Changes in associates accounted for using equity method	4,834			4,834
Ending Balance at Dec. 31, 2021	24,142,215		7,272,401	6,055,621	2,070,505		8,521,848	(86,025)	307,865
Profit for the year	3,439,697						3,439,697
Other comprehensive income (loss)	184,329						177,886	68,656	(62,213)
Total comprehensive income (loss) for the year	3,624,026						3,617,583	68,656	(62,213)
Appropriation of prior year's earnings:
Legal reserve					505,482		(505,482)
Cash dividends	(3,127,133)						(3,127,133)
Changes in associates accounted for using equity method	152			152
Ending Balance at Dec. 31, 2022	24,639,260		7,272,401	6,055,773	2,575,987		8,506,816	(17,369)	245,652
Profit for the year	1,967,565	$ 64,258					1,967,565
Other comprehensive income (loss)	(170,976)	(5,584)					8,947	16,713	(153,542)	$ (43,094)
Total comprehensive income (loss) for the year	1,796,589	58,674					1,976,512	16,713	(153,542)	(43,094)
Appropriation of prior year's earnings:
Legal reserve					354,986		(354,986)
Cash dividends	(1,672,652)						(1,672,652)
Ending Balance at Dec. 31, 2023	$ 24,763,197	$ 808,726	$ 7,272,401	$ 6,055,773	$ 2,930,973		$ 8,455,690	$ (656)	$ 92,110	$ (43,094)

- Definition

The amount of change in equity resulting from transactions and other events, other than those changes resulting from transactions with owners in their capacity as owners.

+ References + Details

- Definition

The amount of residual interest in the assets of the entity after deducting all its liabilities.

+ References + Details

- Definition

The total of income less expenses from continuing and discontinued operations, excluding the components of other comprehensive income. [Refer: Other comprehensive income]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 7
-IssueDate 2023-01-01
-Paragraph 18
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=7&code=ifrs-tx-2023-en-r&anchor=para_18_b&doctype=Standard
-URIDate 2023-03-23

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 1
-IssueDate 2023-01-01
-Paragraph 32
-Subparagraph a
-Clause ii
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=1&code=ifrs-tx-2023-en-r&anchor=para_32_a_ii&doctype=Standard
-URIDate 2023-03-23

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 1
-IssueDate 2023-01-01
-Paragraph 24
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=1&code=ifrs-tx-2023-en-r&anchor=para_24_b&doctype=Standard
-URIDate 2023-03-23

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2023-01-01
-Paragraph 28
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2023-en-r&anchor=para_28_b&doctype=Standard
-URIDate 2023-03-23

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Name IFRS
-Number 8
-IssueDate 2023-01-01
-Paragraph 23
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=8&code=ifrs-tx-2023-en-r&anchor=para_23&doctype=Standard
-URIDate 2023-03-23

Reference 6: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 12
-IssueDate 2023-01-01
-Paragraph B10
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=12&code=ifrs-tx-2023-en-r&anchor=para_B10_b&doctype=Appendix&subtype=B
-URIDate 2023-03-23

Reference 7: http://www.xbrl.org/2003/role/exampleRef
-Name IFRS
-Number 17
-IssueDate 2023-01-01
-Paragraph 113
-Subparagraph b
-URI https://taxonomy.ifrs.org/xifrs-link?type=IFRS&num=17&code=ifrs-tx-2023-en-r&anchor=para_113_b&doctype=Standard
-URIDate 2023-03-23

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2023-01-01
-Paragraph 81A
-Subparagraph a
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2023-en-r&anchor=para_81A_a&doctype=Standard
-URIDate 2023-03-23

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 1
-IssueDate 2023-01-01
-Paragraph 106
-Subparagraph d
-Clause i
-URI https://taxonomy.ifrs.org/xifrs-link?type=IAS&num=1&code=ifrs-tx-2023-en-r&anchor=para_106_d_i&doctype=Standard
-URIDate 2023-03-23

+ Details

Non-current Financial Assets at Fair Value Through Other Comprehensive Income - Summary of Non-current Financial Assets at Fair Value Through Other Comprehensive Income (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Financial assets at fair value through other comprehensive income [line items]
Designation of equity instruments	$ 120,317	$ 338,102
Foreign unlisted stocks [member]
Financial assets at fair value through other comprehensive income [line items]
Designation of equity instruments	38,534	38,534
Valuation adjustments [member]
Financial assets at fair value through other comprehensive income [line items]
Designation of equity instruments	$ 81,783	$ 299,568

Other income

12 Months Ended

Dec. 31, 2023

Other Income [Abstract]

Other income

26.

Other income


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Rental income	17,326	35,848	48,264
Grant income	12,480	21,327	22,727
Dividend income	4,690	9,816	6,592
	34,496	66,991	77,583

Capital stock

12 Months Ended

Dec. 31, 2023

Issued capital [abstract]

Capital stock

19.

Capital stock

As of December 31, 2023, the Company’s authorized capital was NT$9,700,000 thousand, consisting of 970,000 thousand ordinary shares, and the paid-in capital was NT$7,272,401 thousand with a par value of NT$10 per share, consisting of 727,240 thousand ordinary shares. All proceeds from shares issued have been collected.

As of December 31, 2023, the outstanding ADSs were approximately 4,234,970 units representing 84,699 thousand ordinary shares and each ADS represents 20 ordinary shares of the Company. The major terms and conditions of the ADSs are summarized as follows:

(a)

Voting rights:

ADS holders have no right to directly attend, vote or speak in shareholders’ meetings with respect to the deposited shares. The depository bank shall vote on behalf of ADS holders or provide voting instruction to the designated person of the Company. The depository bank shall vote in the manner as instructed by ADS holders.

(b)

Distribution of dividends:

ADS holders are deemed to have the same rights as holders of ordinary shares with respect to the distribution of dividends.

The number of the Company’s ordinary shares outstanding as of January 1 and December 31 of 2021, 2022 and 2023 were all 727,240 thousand shares, respectively.

Financial risk management and fair values of financial instruments (Tables)

12 Months Ended

Dec. 31, 2023

Disclosure of detailed information about financial instruments [abstract]

Summary of Financial Instruments by Category

(a)

Financial instruments by category


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Financial assets
Financial assets at fair value through profit or loss
Financial assets mandatorily measured at fair value through profit or loss	128,224	42,735
Financial assets at fair value through other comprehensive income
Designation of equity instruments	338,102	120,317
Financial assets at amortized cost
Cash and cash equivalents	9,896,604	12,354,035
Financial assets at amortized cost	136,093	78,477
Accounts receivable	4,381,563	5,326,381
Other receivables	131,863	44,576
Refundable deposits	21,771	20,707
	15,034,220	17,987,228
Financial liabilities
Financial liabilities at amortized cost
Notes payable	132	484
Accounts payable	560,802	784,919
Other payables	3,796,481	3,479,045
Other payables – related parties	—	58,549
Long-term bank loans (including current portion)	13,967,801	14,911,719
Lease liabilities (including current portion)	920,402	1,065,401
Guarantee deposits	21,600	21,235
	19,267,218	20,321,352

Information on Assets and Liabilities Denominated in Foreign Currencies whose Values would be Materially Affected by Exchange Rate Fluctuations

The information on assets and liabilities denominated in foreign currencies whose values would be materially affected by the exchange rate fluctuations is as follows:


	December 31, 2022
	Foreign currency	Exchange rate	Carrying amount (NT$000)
(Foreign currency: functional currency)
Financial assets
Monetary items
US$000	208,989	30.7100	6,418,052
JPY000	114,940	0.2324	26,712
RMB000	7,199	4.4080	31,733
Non-monetary items
JPY000	1,454,830	0.2324	338,102
RMB000	927,037	4.4080	4,086,378
Financial liabilities
Monetary items
US$000	11,031	30.7100	338,762
JPY000	1,587,732	0.2324	368,989


	December 31, 2023
	Foreign currency	Exchange rate	Carrying amount (NT$000)
(Foreign currency: functional currency)
Financial assets
Monetary items
US$000	149,837	30.7050	4,600,745
JPY000	188,904	0.2172	41,030
RMB000	5,595	4.3270	24,210
Non-monetary items
JPY000	553,946	0.2172	120,317
Financial liabilities
Monetary items
US$000	21,175	30.7050	650,178
JPY000	1,102,264	0.2172	239,412

Details of Exposure to Currency Risk Arising from Recognized Monetary Assets or Liabilities Denominated in a Currency Other Than Functional Currency

Analysis of foreign currency market risk arising from significant foreign exchange variations:


	Year ended December 31, 2021
	Sensitivity analysis
	Change in exchange rate	Effect on profit (loss) (NT$000)	Effect on other comprehensive income (NT$000)
Financial assets
Monetary items
US$000	5%	260,390	—
JPY000	5%	1,702	—
RMB000	5%	1,074	—
Financial liabilities
Monetary items
US$000	5%	73,410	—
JPY000	5%	13,103	—


	Year ended December 31, 2022
	Sensitivity analysis
	Change in exchange rate	Effect on profit (loss) (NT$000)	Effect on other comprehensive income (NT$000)
Financial assets
Monetary items
US$000	5%	320,903	—
JPY000	5%	1,336	—
RMB000	5%	1,587	—
Financial liabilities
Monetary items
US$000	5%	16,938	—
JPY000	5%	18,449	—


	Year ended December 31, 2023
	Sensitivity analysis
	Change in exchange rate	Effect on profit (loss) (NT$000)	Effect on other comprehensive income (NT$000)
Financial assets
Monetary items
US$000	5%	230,037	—
JPY000	5%	2,052	—
RMB000	5%	1,211	—
Financial liabilities
Monetary items
US$000	5%	32,509	—
JPY000	5%	11,971	—

Summary of Loss Rate Methodology

As of December 31, 2022 and 2023 the loss rate methodologies are as follows:


	December 31, 2022
	Contract assets	Accounts receivable (including related parties)	Other receivables (including related parties)
	NT$000	NT$000	NT$000
Expected loss rate	0.060%	0.060%	0.060%
Total carrying amount	381,587	4,384,232	131,908
Loss allowance	(229)	(2,669)	(45)


	December 31, 2023
	Contract assets	Accounts receivable (including related parties)	Other receivables (including related parties)
	NT$000	NT$000	NT$000
Expected loss rate	0.045%	0.045%	0.045%
Total carrying amount	384,057	5,328,835	44,589
Loss allowance	(174)	(2,454)	(13)

Summary of Movements in Relation to Loss Allowance for Contract Assets, Accounts Receivable and Other Receivables

Under the simplified approach, movements in relation to loss allowance for contract assets, accounts receivable, and other receivables are as follows:


	2021
	Contract assets	Accounts receivable (including related parties)	Other receivables (including related parties)
	NT$000	NT$000	NT$000
January 1	(117)	(1,620)	(10)
Provision for impairment loss	(3)	(290)	(6)
December 31	(120)	(1,910)	(16)


	2022
	Contract assets	Accounts receivable (including related parties)	Other receivables (including related parties)
	NT$000	NT$000	NT$000
January 1	(120)	(1,910)	(16)
Provision for impairment loss	(109)	(759)	(29)
December 31	(229)	(2,669)	(45)


	2023
	Contract assets	Accounts receivable (including related parties)	Other receivables (including related parties)
	NT$000	NT$000	NT$000
January 1	(229)	(2,669)	(45)
Reversal of impairment loss	55	215	32
December 31	(174)	(2,454)	(13)

Maturity Profile of Non-derivative Financial Liabilities Based on Contracted Undiscounted Payments


	December 31, 2022
	Within 1 year	1 to 3 years	3 to 5 years	Over 5 years	Total
	NT$000	NT$000	NT$000	NT$000	NT$000
Non-derivative financial liabilities
Long-term bank loans	1,699,165	5,675,288	5,354,335	1,914,280	14,643,068
Lease liabilities	174,460	182,767	57,057	704,503	1,118,787
Guarantee deposits	—	—	—	21,600	21,600
	1,873,625	5,858,055	5,411,392	2,640,383	15,783,455


	December 31, 2023
	Within 1 year	1 to 3 years	3 to 5 years	Over 5 years	Total
	NT$000	NT$000	NT$000	NT$000	NT$000
Non-derivative financial liabilities
Long-term bank loans	2,469,744	7,506,844	4,273,199	1,330,797	15,580,584
Lease liabilities	267,759	250,104	57,856	681,975	1,257,694
Guarantee deposits	—	—	—	21,235	21,235
	2,737,503	7,756,948	4,331,055	2,034,007	16,859,513

Summary of Natures of Assets and Liabilities

The related information of natures of the assets and liabilities are as follows:


	December 31, 2022
	Level 1	Level 2	Level 3	Total
	NT$000	NT$000	NT$000	NT$000
Assets
Recurring fair value measurements
Financial assets at fair value through profit or loss
- Listed stocks	128,224	—	—	128,224
Financial assets at fair value through other comprehensive income
- Foreign unlisted stocks	—	—	338,102	338,102
	128,224	—	338,102	466,326


	December 31, 2023
	Level 1	Level 2	Level 3	Total
	NT$000	NT$000	NT$000	NT$000
Assets
Recurring fair value measurements
Financial assets at fair value through profit or loss
- Listed stocks	42,735	—	—	42,735
Financial assets at fair value through other comprehensive income
- Foreign unlisted stocks	—	—	120,317	120,317
	42,735	—	120,317	163,052

Summary of Movements of Level 3

(d)

The following table shows the movements of Level 3 for the years ended December 31, 2022 and 2023:


	Equity instruments
	2022	2023
	NT$000	NT$000
January 1	384,521	338,102
Gains or losses recognized in other comprehensive income
Recorded as unrealized loss on valuation of financial assets at fair value through other comprehensive income	(46,419)	(217,785)
Purchases	—	12,500
Reclassified as investments accounted for using equity method	—	(12,500)
December 31	338,102	120,317

Summary of Qualitative Information and Sensitivity Analysis of Changes in Significant Unobservable Inputs Under Valuation Model Used in Level 3 Fair Value Measurement

(f)

The following is the qualitative information and sensitivity analysis of changes in significant unobservable inputs under valuation model used in Level 3 fair value measurement:


	Fair value as of December 31, 2022	Valuation technique	Significant unobservable input	Range	Relationship of inputs to fair value
	NT$000
Non-derivative equity instrument:
Foreign unlisted stocks	338,102	Comparable companies	Enterprise value to EBITDA multiple	4.82	The higher the multiple, the higher the fair value
			Discount for lack of marketability	15.80%	The higher the discount for lack of marketability, the lower the fair value


	Fair value as of December 31, 2023	Valuation technique	Significant unobservable input	Range	Relationship of inputs to fair value
	NT$000
Non-derivative equity instrument:
Foreign unlisted stocks	120,317	Comparable companies	Enterprise value to EBITDA multiple	8.23	The higher the multiple, the higher the fair value
			Price to book ratio multiple	1.64	The higher the multiple, the higher the fair value
			Discount for lack of marketability	15.70%	The higher the discount for lack of marketability, the lower the fair value

Summary of Effect of Profit or Loss or of Other Comprehensive Income from Financial Assets Categorized

          
         December 31, 2022

          
         Recognized in 
profit or loss

         Recognized in other
comprehensive income

          
         Input

         Change

         Favorable
change

         Unfavorable
change

         Favorable
change

         Unfavorable
change

         Financial assets:

           Foreign unlisted stocks

         Enterprise value to 
  EBITDA multiple

         ±1%

         —

         —

         2,876

         2,883

          
         Discount for lack 
  of marketability

         ±1%

         —

         —

         3,990

         4,039


			December 31, 2023
			Recognized in profit or loss		Recognized in other comprehensive income
	Input	Change	Favorable change	Unfavorable change	Favorable change	Unfavorable change
			NT$000	NT$000	NT$000	NT$000
Financial assets:
Foreign unlisted stocks	Enterprise value to EBITDA multiple	±1%	—	—	748	709
	Price to book ratio multiple	±1%	—	—	30	30
	Discount for lack of marketability	±1%	—	—	1,453	1,413
			—	—	2,231	2,152

Financial Statements Schedule: Valuation and Qualifying Accounts (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Allowance for Impairment of property, plant and equipment [member]
Disclosure of details of valuation and qualifying accounts [Line Items]
January 1	$ 194,467	$ 183,179	$ 182,002
Additions charged to expense or deduction of revenue	9,236	12,721	4,843
Deduction/Write-offs/Reversal		(1,433)	(3,666)
December 31	203,703	194,467	183,179
Allowance for Impairment of Obsolescence and Decline in Market Value of Inventories [Member]
Disclosure of details of valuation and qualifying accounts [Line Items]
January 1	105,630	121,586	79,815
Additions charged to expense or deduction of revenue	80,633		41,771
Deduction/Write-offs/Reversal		(15,956)
December 31	186,263	105,630	121,586
Provision for deficiency compensation [member]
Disclosure of details of valuation and qualifying accounts [Line Items]
January 1	26,643	4,281	3,463
Additions charged to expense or deduction of revenue	21,495	79,827	11,898
Deduction/Write-offs/Reversal	(14,574)	(57,465)	(11,080)
December 31	33,564	26,643	4,281
Sales for allowance [member]
Disclosure of details of valuation and qualifying accounts [Line Items]
January 1	37,123	9,849	9,864
Additions charged to expense or deduction of revenue	112,488	94,641	34,744
Deduction/Write-offs/Reversal	(111,944)	(67,367)	(34,759)
December 31	$ 37,667	$ 37,123	$ 9,849

Related party transactions

12 Months Ended

Dec. 31, 2023

Related party transactions

35.

Related party transactions

Parent and ultimate controlling party

The Company has neither a parent company nor an ultimate controlling party. The transactions between the Company and its subsidiaries were eliminated in the accompanying consolidated financial statements and were not disclosed herein. The transactions between the Group and other related parties are as follows.

Names of related parties and relationship


Name		Relationship
Unimos Shanghai		Associate
JMC		Associate
Daypower Energy		Associate
Siliconware Precision Industries Co., Ltd. (“SPIL”)		Entity that has significant influence over the Company

Significant related party transactions

(a)

Payable to equipment suppliers


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Daypower Energy	—	58,549

(b)

Acquisition of property, plant and equipment


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
SPIL	—	—	35,261

Key management personnel compensation


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Salaries and other short-term employee benefits	243,405	211,620	176,702
Post-employment compensation	2,156	2,197	2,158
	245,561	213,817	178,860

Financial Risk Management and Fair Values of Financial Instruments - Information on Assets and Liabilities Denominated in Foreign Currencies whose Values would be Materially Affected by Exchange Rate Fluctuations (Detail) ¥ in Thousands, ¥ in Thousands, $ in Thousands, $ in Thousands	Dec. 31, 2023 JPY (¥) $ / ¥ $ / ¥ $ / $	Dec. 31, 2023 TWD ($) $ / ¥ $ / ¥ $ / $	Dec. 31, 2023 CNY (¥) $ / ¥ $ / ¥ $ / $	Dec. 31, 2023 USD ($) $ / ¥ $ / ¥ $ / $	Dec. 31, 2022 JPY (¥) $ / ¥ $ / ¥ $ / $	Dec. 31, 2022 TWD ($) $ / ¥ $ / ¥ $ / $	Dec. 31, 2022 CNY (¥) $ / ¥ $ / ¥ $ / $	Dec. 31, 2022 USD ($) $ / ¥ $ / ¥ $ / $
Disclosure of detailed information about financial instruments [Line Items]
Assets denominated in foreign currencies \| $		$ 17,987,228				$ 15,034,220
Exchange rate	30.62	30.62	30.62	30.62
Currency Risk [member] \| US$ [member]
Disclosure of detailed information about financial instruments [Line Items]
Assets denominated in foreign currencies		$ 4,600,745		$ 149,837		6,418,052		$ 208,989
Liabilities denominated in foreign currencies		$ 650,178		$ 21,175		$ 338,762		$ 11,031
Currency Risk [member] \| US$ [member] \| Financial Liability [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate \| $ / $	30.705	30.705	30.705	30.705	30.71	30.71	30.71	30.71
Currency Risk [member] \| US$ [member] \| Financial Asset [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate \| $ / $	30.705	30.705	30.705	30.705	30.71	30.71	30.71	30.71
Currency Risk [member] \| JPY [member]
Disclosure of detailed information about financial instruments [Line Items]
Assets denominated in foreign currencies	¥ 188,904	$ 41,030			¥ 114,940	$ 26,712
Liabilities denominated in foreign currencies	¥ 1,102,264	$ 239,412			¥ 1,587,732	$ 368,989
Currency Risk [member] \| JPY [member] \| Financial Liability [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate	0.2172	0.2172	0.2172	0.2172	0.2324	0.2324	0.2324	0.2324
Currency Risk [member] \| JPY [member] \| Financial Asset [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate	0.2172	0.2172	0.2172	0.2172	0.2324	0.2324	0.2324	0.2324
Currency Risk [member] \| RMB [member]
Disclosure of detailed information about financial instruments [Line Items]
Assets denominated in foreign currencies		$ 24,210	¥ 5,595			$ 31,733	¥ 7,199
Currency Risk [member] \| RMB [member] \| Financial Asset [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate	4.327	4.327	4.327	4.327	4.408	4.408	4.408	4.408
Other Risks [Member] \| JPY [member]
Disclosure of detailed information about financial instruments [Line Items]
Assets denominated in foreign currencies	¥ 553,946	$ 120,317			¥ 1,454,830	$ 338,102
Other Risks [Member] \| JPY [member] \| Financial Asset [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate	0.2172	0.2172	0.2172	0.2172	0.2324	0.2324	0.2324	0.2324
Other Risks [Member] \| RMB [member]
Disclosure of detailed information about financial instruments [Line Items]
Assets denominated in foreign currencies						$ 4,086,378	¥ 927,037
Other Risks [Member] \| RMB [member] \| Financial Asset [member]
Disclosure of detailed information about financial instruments [Line Items]
Exchange rate					4.408	4.408	4.408	4.408

Financial assets at fair value through profit or loss

12 Months Ended

Dec. 31, 2023

Financial assets at fair value through profit or loss [abstract]

Financial assets at fair value through profit or loss


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Current:
Financial assets mandatorily measured at fair value through profit or loss
Listed stocks	171,988	53,747
Valuation adjustment	(43,764)	(11,012)
	128,224	42,735

Amounts recognized in profit or loss in relation to the financial assets at fair value through profit or loss are listed below:


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Financial assets mandatorily measured at fair value through profit or loss
Listed stocks	13,673	(75,211)	22,001
Beneficiary certificates*	2,530	5,807	17,253
Foreign partnership interests	(941)	—	—
	15,262	(69,404)	39,254

* Beneficiary certificates represent money market funds the Company held during the reporting period. As of December 31, 2021, 2022 and 2023, there were no beneficiary certificates classified as current financial assets at fair value through profit or loss (“FVTPL”).

No financial assets at FVTPL were pledged to others.

Information relating to price risk of financial assets at FVTPL is provided in Note 41 a).

Pensions - Movements in Net Defined Benefit Liability (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of net defined benefit liability (asset) [Line Items]
Beginning balance	$ (259,215)	$ (503,288)	$ (511,651)
Current service cost	(133)	(257)	(237)
Interest (expense) income	(3,709)	(3,428)	(2,492)
Total	(263,057)	(506,973)	(514,380)
Return on plan assets (excluding amounts included in interest income or expense)	3,187	34,550	5,613
Impact on changes in demographic assumptions	14,216		(20,022)
Financial assumption movement effect	(7,103)	73,218	23,757
Experience adjustments	399	114,466	(24,347)
Gain (loss) on remeasurement, net defined benefit liability (asset)	10,699	222,234	(14,999)
Pension fund contribution	25,021	25,524	26,091
Ending balance	(227,337)	(259,215)	(503,288)
Present Value of Defined Benefit Obligation [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Beginning balance	(759,548)	(959,677)	(943,391)
Current service cost	(133)	(257)	(237)
Interest (expense) income	(11,150)	(6,589)	(4,629)
Total	(770,831)	(966,523)	(948,257)
Impact on changes in demographic assumptions	14,216		(20,022)
Financial assumption movement effect	(7,103)	73,218	23,757
Experience adjustments	399	114,466	(24,347)
Gain (loss) on remeasurement, net defined benefit liability (asset)	7,512	187,684	(20,612)
Paid pension	19,128	19,291	9,192
Ending balance	(744,191)	(759,548)	(959,677)
Fair Value of Plan Assets [member]
Disclosure of net defined benefit liability (asset) [Line Items]
Beginning balance	500,333	456,389	431,740
Interest (expense) income	7,441	3,161	2,137
Total	507,774	459,550	433,877
Return on plan assets (excluding amounts included in interest income or expense)	3,187	34,550	5,613
Gain (loss) on remeasurement, net defined benefit liability (asset)	3,187	34,550	5,613
Pension fund contribution	25,021	25,524	26,091
Paid pension	(19,128)	(19,291)	(9,192)
Ending balance	$ 516,854	$ 500,333	$ 456,389

Pensions (Tables)

12 Months Ended

Dec. 31, 2023

Disclosure of defined benefit plans [abstract]

Summary of Amounts Recognized in Statements of Financial Position

(a)

The amounts recognized in the statements of financial position are as follows:


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Present value of defined benefit obligations	(759,548)	(744,191)
Fair value of plan assets	500,333	516,854
Net defined benefit liability	(259,215)	(227,337)

Summary of Movements in net Defined Benefit Liability

(b)

Movements in net defined benefit liability are as follows:


	2021
	Present value of defined benefit obligations	Fair value of plan assets	Net defined benefit liability
	NT$000	NT$000	NT$000
January 1	(943,391)	431,740	(511,651)
Current services cost	(237)	—	(237)
Interest (expense) income	(4,629)	2,137	(2,492)
	(948,257)	433,877	(514,380)
Remeasurements:
Return on plan assets (excluding amounts included in interest income or expense)	—	5,613	5,613
Impact on changes in demographic assumptions	(20,022)	—	(20,022)
Financial assumption movement effect	23,757	—	23,757
Experience adjustments	(24,347)	—	(24,347)
	(20,612)	5,613	(14,999)
Pension fund contribution	—	26,091	26,091
Paid pension	9,192	(9,192)	—
December 31	(959,677)	456,389	(503,288)


	2022
	Present value of defined benefit obligations	Fair value of plan assets	Net defined benefit liability
	NT$000	NT$000	NT$000
January 1	(959,677)	456,389	(503,288)
Current services cost	(257)	—	(257)
Interest (expense) income	(6,589)	3,161	(3,428)
	(966,523)	459,550	(506,973)
Remeasurements:
Return on plan assets (excluding amounts included in interest income or expense)	—	34,550	34,550
Financial assumption movement effect	73,218	—	73,218
Experience adjustments	114,466	—	114,466
	187,684	34,550	222,234
Pension fund contribution	—	25,524	25,524
Paid pension	19,291	(19,291)	—
December 31	(759,548)	500,333	(259,215)


	2023
	Present value of defined benefit obligations	Fair value of plan assets	Net defined benefit liability
	NT$000	NT$000	NT$000
January 1	(759,548)	500,333	(259,215)
Current services cost	(133)	—	(133)
Interest (expense) income	(11,150)	7,441	(3,709)
	(770,831)	507,774	(263,057)
Remeasurements:
Return on plan assets (excluding amounts included in interest income or expense)	—	3,187	3,187
Impact on changes in demographic assumptions	14,216	—	14,216
Financial assumption movement effect	(7,103)	—	(7,103)
Experience adjustments	399	—	399
	7,512	3,187	10,699
Pension fund contribution	—	25,021	25,021
Paid pension	19,128	(19,128)	—
December 31	(744,191)	516,854	(227,337)

Principal Actuarial Assumptions

(d)

The principal actuarial assumptions used were as follows:


	Year ended December 31,
	2022	2023
Discount rate	1.50%	1.40%
Future salary increase	3.50%	3.50%

Sensitivity Analysis of Present Value of Defined Benefit Obligations Effected by Changes of Significant Actuarial Assumptions

The present value of defined benefit obligations is affected by the change in actuarial assumption. The analysis was as follows:


	Discount rate		Future salary increase
	Increase 0.25%	Decrease 0.25%	Increase 0.25%	Decrease 0.25%
	NT$000	NT$000	NT$000	NT$000
December 31, 2022
Effect on present value of defined benefit obligations	(20,992)	21,860	21,385	(20,651)
December 31, 2023
Effect on present value of defined benefit obligations	(17,562)	18,228	17,817	(17,262)

Analysis of Timing of the Future Pension Payment

(f)

As of December 31, 2023, the weighted average duration of that retirement plan is 9.7 years. The analysis of timing of the future pension payment was as follows:


		December 31, 2023
		NT$000
Within 1 year		69,288
1-2 years		42,487
2-5 years		115,279
5-10 years		181,850
		408,904

Accounts receivable (Tables)

12 Months Ended

Dec. 31, 2023

Accounts Receivable [Abstract]

Summary of Accounts and notes receivable


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Accounts receivable	4,384,232	5,328,835
Less: Loss allowance	(2,669)	(2,454)
	4,381,563	5,326,381

Aging of Accounts Receivable which are Past Due but not Impaired


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Current	4,357,073	5,326,523
Within 1 month	27,159	2,089
1-2 months	—	223
	4,384,232	5,328,835

Accounts receivable

12 Months Ended

Dec. 31, 2023

Accounts Receivable [Abstract]

Accounts receivable


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Accounts receivable	4,384,232	5,328,835
Less: Loss allowance	(2,669)	(2,454)
	4,381,563	5,326,381

The Group’s credit term granted to customers is 30~90 days. Receivables do not bear interest. The loss allowance is determined based on the credit quality of customers. Information relating to credit risk is provided in Note 41 a).

The aging analysis of accounts receivable based on past due date are as follows:


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Current	4,357,073	5,326,523
Within 1 month	27,159	2,089
1-2 months	—	223
	4,384,232	5,328,835

As of December 31, 2022 and 2023, accounts receivable were all from contracts with customers. And as of January 1, 2022, the balance of accounts receivable from contracts with customers was NT$6,344,246 thousand.

Without taking into account of any collateral held or other credit enhancements, the amount that best reflects the Group’s maximum exposure to credit risk in respect of the accounts receivable is the carrying amount at the end of each reporting period.

No accounts receivable of the Group were pledged to others.

Significant contingent liabilities and unrecognized contract commitments - Additional Information (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Capital commitments [abstract]
Amounts guaranteed by the financial institutions	$ 71,900	$ 135,600

Financial Risk Management and Fair Values of Financial Instruments - Details of Exposure to Currency Risk Arising from Recognized Monetary Assets or Liabilities Denominated in a Currency Other Than Functional Currency (Detail) - Currency Risk [member] - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Financial assets, class [member] \| US$ [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Change in exchange rate	5.00%	5.00%	5.00%
Financial assets, class [member] \| JPY [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Change in exchange rate	5.00%	5.00%	5.00%
Financial assets, class [member] \| RMB [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Change in exchange rate	5.00%	5.00%	5.00%
Financial liabilities, class [member] \| US$ [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Change in exchange rate	5.00%	5.00%	5.00%
Financial liabilities, class [member] \| JPY [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Change in exchange rate	5.00%	5.00%	5.00%
Profit and Loss [member] \| Financial assets, class [member] \| US$ [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Effect of change in exchange rate	$ 230,037	$ 320,903	$ 260,390
Profit and Loss [member] \| Financial assets, class [member] \| JPY [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Effect of change in exchange rate	2,052	1,336	1,702
Profit and Loss [member] \| Financial assets, class [member] \| RMB [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Effect of change in exchange rate	1,211	1,587	1,074
Profit and Loss [member] \| Financial liabilities, class [member] \| US$ [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Effect of change in exchange rate	32,509	16,938	73,410
Profit and Loss [member] \| Financial liabilities, class [member] \| JPY [member]
Disclosure of nature and extent of risks arising from financial instruments [Line Items]
Effect of change in exchange rate	$ 11,971	$ 18,449	$ 13,103

Other gains and losses - Summary of Other gains and losses (Details) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of Other gains and losses [Abstract]
Foreign exchange (losses) gains, net	$ 78,170		$ 448,097	$ (89,152)
Gain (loss) on valuation of financial assets at fair value through profit or loss	39,254	$ 1,282	(69,404)	15,262
Reimbursement of ADSs service charge	2,121		2,412	2,284
Compensation income	20		174	1,524
Others	15,936		5,288	4,253
Total	$ 135,501	$ 4,425	$ 386,567	$ (65,829)

Financial assets at fair value through profit or loss (Tables)

12 Months Ended

Dec. 31, 2023

Financial assets at fair value through profit or loss [abstract]

Summary of Financial Assets at Fair Value Through Profit or Loss


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Current:
Financial assets mandatorily measured at fair value through profit or loss
Listed stocks	171,988	53,747
Valuation adjustment	(43,764)	(11,012)
	128,224	42,735

Summary of Amounts recognized in Profit or Loss in Relation to Financial Assets at Fair Value Through Profit or Loss

Amounts recognized in profit or loss in relation to the financial assets at fair value through profit or loss are listed below:


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Financial assets mandatorily measured at fair value through profit or loss
Listed stocks	13,673	(75,211)	22,001
Beneficiary certificates*	2,530	5,807	17,253
Foreign partnership interests	(941)	—	—
	15,262	(69,404)	39,254

No financial assets at FVTPL were pledged to others.

Information relating to price risk of financial assets at FVTPL is provided in Note 41 a).

Investments accounted for using equity method - Details of Investment in Associates (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Disclosure of associates [line items]
Carrying amount	$ 290,542	$ 9,489	$ 4,353,448
JMC ELECTRONICS CO., LTD. [member]
Disclosure of associates [line items]
Carrying amount	277,076		267,070
Unimos Shanghai [member]
Disclosure of associates [line items]
Carrying amount			$ 4,086,378
Daypower Energy [member]
Disclosure of associates [line items]
Carrying amount	$ 13,466

Income tax expense (Tables)

12 Months Ended

Dec. 31, 2023

Income tax expense [abstract]

Major Components of Income Tax Expense

(a)

Components of income tax expense:


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Current income tax:
Current income tax on profits for the period	1,109,752	771,378	426,878
Income tax on unappropriated retained earnings	227,467	159,744	85,607
Prior year income tax overestimation	(184,284)	(255,935)	(182,778)
Total current income tax	1,152,935	675,187	329,707
Deferred income tax:
Relating to origination and reversal of temporary differences	(54,617)	(87,012)	(29,046)
Income tax expense	1,098,318	588,175	300,661

Deferred Tax Charged to Other Comprehensive Income

(b)

The income tax (charge)/credit relating to components of other comprehensive income are as follows:


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income	30,459	(12,559)	(51,638)
Remeasurement of defined benefit obligations	(2,999)	44,447	2,140
	27,460	31,888	(49,498)

Reconciliation of Income Tax Expense and Accounting Profit Before Income Tax

Reconciliation of income tax expense and the accounting profit:


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Tax calculated based on profit before tax and statutory tax rate	1,207,605	804,086	451,676
Effects from adjustments based on regulation	(152,618)	(131,873)	(74,094)
Gain on investment in associates	—	11,923	19,228
Prior year income tax overestimation	(184,284)	(255,935)	(182,778)
Income tax on unappropriated retained earnings	227,467	159,744	85,607
Effect of different tax rates in countries in which the Group operates	148	230	1,022
Income tax expense	1,098,318	588,175	300,661

Details of Deferred Tax Assets (Liabilities)

The amounts of deferred tax assets or liabilities resulting from temporary differences and investment tax credits are as follows:


	2021
	January 1	Recognized in profit or loss	Recognized in other comprehensive income	December 31
	NT$000	NT$000	NT$000	NT$000
Deferred tax assets
Loss on inventories	15,963	8,354	—	24,317
Property, plant and equipment	36,401	235	—	36,636
Provisions	2,678	171	—	2,849
Deferred revenue	21,144	(6,506)	—	14,638
Net defined benefit liability	98,921	(4,672)	2,999	97,248
Unrealized exchange losses	9,915	(7,754)	—	2,161
Others	669	2,080	—	2,749
Total	185,691	(8,092)	2,999	180,598
Deferred tax liabilities
Property, plant and equipment	(255,484)	62,797	—	(192,687)
Financial assets at fair value through other comprehensive income	(54,943)	—	(30,459)	(85,402)
Others	—	(88)	—	(88)
Total	(310,427)	62,709	(30,459)	(278,177)
Information presented on statements of financial position:
Deferred tax assets	185,691			180,598
Deferred tax liabilities	(310,427)			(278,177)


	2022
	January 1	Recognized in profit or loss	Recognized in other comprehensive income	December 31
	NT$000	NT$000	NT$000	NT$000
Deferred tax assets
Loss on inventories	24,317	(3,191)	—	21,126
Property, plant and equipment	36,636	2,258	—	38,894
Provisions	2,849	10,010	—	12,859
Deferred revenue	14,638	(6,506)	—	8,132
Net defined benefit liability	97,248	(4,368)	(44,447)	48,433
Unrealized exchange losses	2,161	22,056	—	24,217
Others	2,749	2,876	—	5,625
Total	180,598	23,135	(44,447)	159,286
Deferred tax liabilities
Property, plant and equipment	(192,687)	75,713	—	(116,974)
Financial assets at fair value through other comprehensive income	(85,402)	—	12,559	(72,843)
Gain on investment in associates	—	(11,923)	—	(11,923)
Others	(88)	87	—	(1)
Total	(278,177)	63,877	12,559	(201,741)
Information presented on statements of financial position:
Deferred tax assets	180,598			159,286
Deferred tax liabilities	(278,177)			(201,741)


	2023
	January 1	Recognized in profit or loss	Recognized in other comprehensive income	December 31
	NT$000	NT$000	NT$000	NT$000
Deferred tax assets
Loss on inventories	21,126	16,127	—	37,253
Property, plant and equipment	38,894	1,847	—	40,741
Provisions	12,859	1,518	—	14,377
Deferred revenue	8,132	(6,506)	—	1,626
Net defined benefit liability	48,433	(4,236)	(2,140)	42,057
Unrealized exchange losses	24,217	(6,032)	—	18,185
Others	5,625	3,418	—	9,043
Total	159,286	6,136	(2,140)	163,282
Deferred tax liabilities
Property, plant and equipment	(116,974)	42,142	—	(74,832)
Financial assets at fair value through other comprehensive income	(72,843)	—	51,638	(21,205)
Gain on investment in associates	(11,923)	(19,228)	—	(31,151)
Others	(1)	(4)	—	(5)
Total	(201,741)	22,910	51,638	(127,193)
Information presented on statements of financial position:
Deferred tax assets	159,286			163,282
Deferred tax liabilities	(201,741)			(127,193)

Pensions - Additional Information (Detail) $ in Thousands	12 Months Ended
Pensions - Additional Information (Detail) $ in Thousands	Dec. 31, 2023 TWD ($) Unit	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of defined benefit plans [Line Items]
Weighted average duration of defined benefit obligation	9 years 8 months 12 days
Defined benefit plans expected contribution \| $	$ 24,000
ChipMOS Shanghai [Member]
Disclosure of defined benefit plans [Line Items]
Employer contribution percentage	16.00%	16.00%	16.00%
Pension costs under defined contribution pension plans \| $	$ 604	$ 380	$ 209
Defined benefit pension plan [Member]
Disclosure of defined benefit plans [Line Items]
Number of units accrued in first tranche \| Unit	2
Duration of first tranche	first 15 years
Number of units accrued in second tranche \| Unit	1
Duration of second tranche	Thereafter 15 years
Maximum number of units accruable under the pension plan \| Unit	45
Benefit measurement period	6 months
Employer contribution percentage	2.00%
Defined contribution pension plan [member]
Disclosure of defined benefit plans [Line Items]
Employer contribution percentage	6.00%
Pension costs under defined contribution pension plans \| $	$ 190,913	$ 201,606	$ 197,076

Leasing arrangements - leasee (Tables)

12 Months Ended

Dec. 31, 2023

Presentation of leases for lessee [abstract]

Summary of carrying amount of right-of-use assets and the depreciation expenses

The carrying amount of right-of-use assets and the depreciation expenses are as follows:


	Carrying amount
	December 31, 2022	December 31, 2023
	NT$000	NT$000
Land	630,969	615,385
Buildings	8,214	7,723
Machinery and equipment	257,196	411,809
Others	2,613	2,585
	898,992	1,037,502


	Depreciation expenses
	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Land	20,486	21,904	21,524
Buildings	9,870	10,861	11,738
Machinery and equipment	247,090	194,059	245,304
Others	1,634	1,997	2,461
	279,080	228,821	281,027

Summary of profit and loss accounts relating to lease contracts

The information on profit or loss accounts relating to lease contracts is as follows:


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Items affecting profit or loss
Interest expense on lease liabilities	15,245	14,556	18,757
Expense on short-term lease contracts	143,791	95,213	55,944

Financial Risk Management and Fair Values of Financial Instruments - Summary of Loss Rate Methodology (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Contract assets [member]
Disclosure of detailed information about financial instruments [Line Items]
Expected loss rate	0.045%	0.06%
Total carrying amount	$ 384,057	$ 381,587
Loss allowance	$ (174)	$ (229)
Accounts receivable including related parties [member]
Disclosure of detailed information about financial instruments [Line Items]
Expected loss rate	0.045%	0.06%
Total carrying amount	$ 5,328,835	$ 4,384,232
Loss allowance	$ (2,454)	$ (2,669)
Other receivable including related parties [member]
Disclosure of detailed information about financial instruments [Line Items]
Expected loss rate	0.045%	0.06%
Total carrying amount	$ 44,589	$ 131,908
Loss allowance	$ (13)	$ (45)

Cover Page	12 Months Ended
Cover Page	Dec. 31, 2023 shares
Document Information [Line Items]
Document Type	20-F
Amendment Flag	false
Document Period End Date	Dec. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Registrant Name	ChipMOS TECHNOLOGIES INC.
Entity Central Index Key	0001123134
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding	727,240,126
Document Annual Report	true
Document Transition Report	false
Entity Interactive Data Current	Yes
Document Shell Company Report	false
Entity Incorporation, State or Country Code	F5
Document Financial Statement Error Correction [Flag]	false
Document Accounting Standard	International Financial Reporting Standards
Entity Voluntary Filers	No
Entity Address, Address Line One	No. 1, R&D Road 1
Entity Address, Address Line Two	Hsinchu Science Park
Entity Address, City or Town	Hsinchu
Entity Address, Country	TW
Entity Address, Postal Zip Code	300-092
ICFR Auditor Attestation Flag	true
Auditor Name	PricewaterhouseCoopers, Taiwan
Auditor Firm ID	1345
Auditor Location	Taipei, Taiwan
Document Registration Statement	false
Securities Act File Number	001-37928
ADR [member]
Document Information [Line Items]
Trading Symbol	IMOS
Title of 12(b) Security	American Depositary Shares
Security Exchange Name	NASDAQ
Ordinary shares [member]
Document Information [Line Items]
Title of 12(b) Security	Common Shares, par value NT$10 per share
No Trading Symbol Flag	true
Security Exchange Name	NASDAQ
Business Contact [Member]
Document Information [Line Items]
Entity Address, Address Line One	No. 1, R&D Road 1
Entity Address, Address Line Two	Hsinchu Science Park
Entity Address, City or Town	Hsinchu
Entity Address, Country	TW
Entity Address, Postal Zip Code	300-092
City Area Code	886
Local Phone Number	3-577-0055
Contact Personnel Name	Silvia Su

Other income (expenses), net

12 Months Ended

Dec. 31, 2023

Other income expenses net [abstract]

Other income (expenses), net

24.

Other income (expenses), net


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Gain on disposal of property, plant and equipment, net	33,935	74,548	18,431
Gain on disposal of scrapped materials	52,254	35,381	44,662
Gain on disposal of items purchased on behalf of others	21,945	19,107	12,729
Gain from lease modifications	891	139	—
Impairment loss on property, plant and equipment	(4,843)	(12,721)	(9,236)
Others	21,405	13,479	19,357
	125,587	129,933	85,943

Non-current assets held for sale - Additional Information (Details)	Dec. 21, 2023
Disclosure of subsidiaries [line items]
Percentage of owned equity investment approved to sell	45.0242%
Unimos Shanghai [member]
Disclosure of subsidiaries [line items]
Percentage of owned equity investment approved to sell	45.0242%

Inventories

12 Months Ended

Dec. 31, 2023

Inventories [abstract]

Inventories

10.

Inventories


	December 31, 2022
	Cost	Allowance for impairment losses	Carrying amount
	NT$000	NT$000	NT$000
Raw materials	3,316,039	(105,630)	3,210,409


	December 31, 2023
	Cost	Allowance for impairment losses	Carrying amount
	NT$000	NT$000	NT$000
Raw materials	2,754,911	(186,263)	2,568,648

The cost of inventories recognized as an expense for the year:


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Cost of revenue	20,103,735	18,611,515	17,723,687
Loss on abandonment	552	9,448	2,483
Allowance for (reversal of) inventory valuation and obsolescence loss	41,770	(15,956)	80,633
	20,146,057	18,605,007	17,806,803

Allowance for inventory valuation and obsolescence loss was recognized due to the change in net realizable value.

No inventories of the Group were pledged to others.

Interest income - Disclosure of interest income (Details) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of Interest Income [Abstract]
Bank deposits	$ 191,265		$ 56,612	$ 8,772
Financial assets at amortized cost	1,861		587	1,187
Other interest income	63			21
Interest income	$ 193,189	$ 6,309	$ 57,199	$ 9,980

Pledged assets

12 Months Ended

Dec. 31, 2023

Disclosure assets pledged as collateral [abstract]

Pledged assets

36.

Pledged assets


		Carrying amount
Assets	Purpose	December 31, 2022	December 31, 2023
		NT$000	NT$000
Non-current financial assets at amortized cost	Lease and bank loan	37,362	37,411
Property, plant and equipment, net
- Land	Bank loan	452,738	454,738
- Buildings	Bank loan	5,385,508	5,299,221
- Machinery and equipment	Bank loan	8,204,983	8,173,618
		14,080,591	13,964,988

Segment Information - Geographic Information of Revenue (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of geographical areas [Line Items]
Revenue	$ 21,356,228	$ 697,460	$ 23,517,064	$ 27,400,035
ROC [member]
Disclosure of geographical areas [Line Items]
Revenue	17,287,574		18,671,142	21,608,567
Japan [member]
Disclosure of geographical areas [Line Items]
Revenue	1,176,163		1,989,805	1,768,460
People's Republic of China ("PRC") [member]
Disclosure of geographical areas [Line Items]
Revenue	1,729,908		1,970,943	1,899,362
Singapore [member]
Disclosure of geographical areas [Line Items]
Revenue	676,088		390,488	1,630,733
Others [member]
Disclosure of geographical areas [Line Items]
Revenue	$ 486,495		$ 494,686	$ 492,913

- Definition

+ References

+ Details

Other equity interest - Summary of Other Equity Interest (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of Other Equity Interest [Line Items]
Beginning balance	$ 228,283
Evaluation adjustment - The Company	(217,785)	$ (7,113)	$ (46,419)	$ 122,514
Ending balance	48,360	$ 1,579	228,283
Financial statements translation differences of foreign operations [member]
Disclosure of Other Equity Interest [Line Items]
Beginning balance	(17,369)		(86,025)	(61,330)
Currency translation differences - The company	16,713		68,656	(24,695)
Ending balance	(656)		(17,369)	(86,025)
Unrealized gain (loss) on valuation of financial assets at fair value through other comprehensive income [member]
Disclosure of Other Equity Interest [Line Items]
Beginning balance	245,652		307,865	194,716
Evaluation adjustment - The Company	(217,785)		(46,419)	122,514
Evaluation adjustment - Associates	12,605		(28,353)	21,094
Evaluation adjustment related tax - The Company	51,638		12,559	(30,459)
Ending balance	92,110		245,652	307,865
Equity directly related to non-current assets held for sale [member]
Disclosure of Other Equity Interest [Line Items]
Currency translation differences - Non-current assets held for sale	(43,094)
Ending balance	(43,094)
Other equity interest [member]
Disclosure of Other Equity Interest [Line Items]
Beginning balance	228,283		221,840	133,386
Currency translation differences - The company	16,713		68,656	(24,695)
Currency translation differences - Non-current assets held for sale	(43,094)
Evaluation adjustment - The Company	(217,785)		(46,419)	122,514
Evaluation adjustment - Associates	12,605		(28,353)	21,094
Evaluation adjustment related tax - The Company	51,638		12,559	(30,459)
Ending balance	$ 48,360		$ 228,283	$ 221,840

Other income (Tables)

12 Months Ended

Dec. 31, 2023

Other Income [Abstract]

Summary of Other income


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Rental income	17,326	35,848	48,264
Grant income	12,480	21,327	22,727
Dividend income	4,690	9,816	6,592
	34,496	66,991	77,583

Investments accounted for using equity method (Tables)

12 Months Ended

Dec. 31, 2023

Investments accounted for using equity method [abstract]

Details of Investment in Associates


Associates	December 31, 2022	December 31, 2023
	NT$000	NT$000
JMC ELECTRONICS CO., LTD. (“JMC”)	267,070	277,076
Unimos Microelectronics (Shanghai) Co., Ltd. (“Unimos Shanghai”) (Note)	4,086,378	—
Daypower Energy	—	13,466
	4,353,448	290,542

Summarized Financial Information for Investment in Material Associates


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Profit for the year from continuing operations	625,733	453,715	1,714
Other comprehensive income (loss), net of income tax	28,843	(28,254)	12,993
Total comprehensive income	654,576	425,461	14,707

Translation into U.S. dollar amounts	12 Months Ended
Translation into U.S. dollar amounts	Dec. 31, 2023
Translation into U S dollar amounts [abstract]
Translation into U.S. dollar amounts	5. Translation into U.S. dollar amounts The Company maintains its accounts and expresses its consolidated financial statements in New Taiwan dollars. For convenience purposes, U.S. dollar amounts presented in the accompanying consolidated financial statements have been translated from New Taiwan dollars to U.S. dollars at the noon buying rate in the City of New York for cable transfers as certified for customs purposes by the Federal Reserve Bank of New York as of December 29, 2023, which was NT$30.62 to US$1.00. These convenience translations should not be construed as representations that the New Taiwan dollar amounts have been, or could in the future be, converted into U.S. dollars at this or any other rate of exchange.

Pledged assets (Tables)

12 Months Ended

Dec. 31, 2023

Disclosure assets pledged as collateral [abstract]

Certain Assets Provided as Collateral Mainly for Long-term Bank Loans and Leases


		Carrying amount
Assets	Purpose	December 31, 2022	December 31, 2023
		NT$000	NT$000
Non-current financial assets at amortized cost	Lease and bank loan	37,362	37,411
Property, plant and equipment, net
- Land	Bank loan	452,738	454,738
- Buildings	Bank loan	5,385,508	5,299,221
- Machinery and equipment	Bank loan	8,204,983	8,173,618
		14,080,591	13,964,988

Financial Assets at Amortized Cost - Summary of Financial Assets at Amortized Cost (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)	Dec. 31, 2023 USD ($)
Financial Instruments At Amortised Cost Category [Line Items]
Time deposits	$ 41,066	$ 98,731		$ 1,341
Restricted bank deposits	37,411	37,362		$ 1,222
Interest income	1,861	587	$ 1,187
Time Deposits
Financial Instruments At Amortised Cost Category [Line Items]
Time deposits	41,066	98,731
Restricted Bank Deposits
Financial Instruments At Amortised Cost Category [Line Items]
Restricted bank deposits	$ 37,411	$ 37,362

Earnings per share (Tables)

12 Months Ended

Dec. 31, 2023

Earnings per share [abstract]

Income and Share Data Used in Basic and Diluted EPS Computations


	Year ended December 31, 2021
	Amount after income tax	Weighted average number of ordinary shares outstanding	Earnings per share
Basic earnings per share	NT$000	In thousands	NT$
Profit attributable to equity holders of the Company	4,937,267	727,240	6.79
Diluted earnings per share
Assumed conversion of all dilutive potential ordinary shares:
Employees’ compensation		15,618
Profit attributable to equity holders of the Company	4,937,267	742,858	6.65


	Year ended December 31, 2022
	Amount after income tax	Weighted average number of ordinary shares outstanding	Earnings per share
Basic earnings per share	NT$000	In thousands	NT$
Profit attributable to equity holders of the Company	3,439,697	727,240	4.73
Diluted earnings per share
Assumed conversion of all dilutive potential ordinary shares:
Employees’ compensation		15,406
Profit attributable to equity holders of the Company	3,439,697	742,646	4.63


	Year ended December 31, 2023
	Amount after income tax	Weighted average number of ordinary shares outstanding	Earnings per share
Basic earnings per share	NT$000	In thousands	NT$
Profit attributable to equity holders of the Company	1,967,565	727,240	2.71
Diluted earnings per share
Assumed conversion of all dilutive potential ordinary shares:
Employees’ compensation		7,698
Profit attributable to equity holders of the Company	1,967,565	734,938	2.68

Non-current assets held for sale

12 Months Ended

Dec. 31, 2023

Non-current assets held for sale

14.

Non-current assets held for sale

On December 21, 2023, the Company's Board of Directors approved its subsidiary ChipMOS BVI to sell the 45.0242% owned equity investment accounted for using equity method in Unimos Shanghai to Suzhou Oriza PuHua Zhixin Equity Investment Partnership (L.P.) and other local Chinese investment management companies. Therefore, the investment accounted for using equity method of Unimos Shanghai have been reclassified as non-current assets held for sale at the carrying amount. The equity transfer is expected to be completed in the first half of 2024.

Assets held for sale:


		December 31, 2023
		NT$000
Investment accounted for using equity method in Unimos Shanghai		4,278,658

Information relating to cumulative income or expense recognized in other comprehensive income relating to disposal assets classified as held for sale is provided in Note 22.

Summary of Material Accounting Policies - Estimated Useful Life for Depreciation of Individual Assets (Detail)	12 Months Ended
	Dec. 31, 2023
Buildings [member] \| Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	1 year
Buildings [member] \| Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	51 years
Machinery and equipment [member] \| Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	1 year
Machinery and equipment [member] \| Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	20 years
Tools [member] \| Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	1 year
Tools [member] \| Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	4 years
Other equipment [member] \| Bottom of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	1 year
Other equipment [member] \| Top of range [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Estimated useful life of individual assets	7 years

Finance costs (Tables)

12 Months Ended

Dec. 31, 2023

Finance costs [Abstract]

Summary of Finance Costs


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Interest expense
Bank loans	116,946	138,731	254,892
Lease liabilities	15,245	14,556	18,757
Others	—	8	—
Less: Amounts capitalized in qualifying assets	(11,193)	(10,856)	(7,692)
	120,998	142,439	265,957
Finance expense	10,186	10,840	433
	131,184	153,279	266,390

Cash and Cash Equivalents - Summary of Cash and Cash Equivalents (Detail) $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Cash and cash equivalents [abstract]
Cash on hand and petty cash	$ 450		$ 450
Checking accounts and demand deposits	1,434,939		2,248,954
Time deposits	10,918,646		7,647,200
Cash and cash equivalents	$ 12,354,035	$ 403,463	$ 9,896,604

Accounts receivable - Additional Information (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Jan. 01, 2022 TWD ($)
Disclosure of financial assets [Line Items]
Accounts receivable, net	$ 5,326,381	$ 173,951	$ 4,381,563
Accounts receivable [member]
Disclosure of financial assets [Line Items]
Accounts receivable, net	$ 5,328,835		$ 4,384,232	$ 6,344,246
Bottom of range [member]
Disclosure of financial assets [Line Items]
Credit term granted to customers	30 days
Top of range [member]
Disclosure of financial assets [Line Items]
Credit term granted to customers	90 days

Property, plant and equipment, net

12 Months Ended

Dec. 31, 2023

Disclosure of detailed information about property, plant and equipment [abstract]

Property, plant and equipment, net

13.

Property, plant and equipment, net


	2021
	Land	Buildings	Machinery and equipment	Tools	Others	Construction in progress and equipment to be inspected	Total
	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000
January 1
Cost	452,738	11,212,129	53,246,474	5,451,547	2,185,299	639,607	73,187,794
Accumulated depreciation and impairment	—	(7,119,843)	(41,898,177)	(4,499,186)	(1,675,902)	—	(55,193,108)
	452,738	4,092,286	11,348,297	952,361	509,397	639,607	17,994,686
January 1	452,738	4,092,286	11,348,297	952,361	509,397	639,607	17,994,686
Additions	—	1,345	11,829	407	189	6,538,932	6,552,702
Disposals	—	—	(66,873)	(9,502)	—	—	(76,375)
Reclassifications	—	673,208	4,890,400	690,346	241,656	(6,495,610)	—
Depreciation expenses	—	(423,283)	(2,896,612)	(795,622)	(239,515)	—	(4,355,032)
Impairment losses	—	—	(4,843)	—	—	—	(4,843)
Exchange adjustment	—	—	(13)	—	(4)	—	(17)
December 31	452,738	4,343,556	13,282,185	837,990	511,723	682,929	20,111,121
December 31
Cost	452,738	11,877,419	57,176,339	5,574,316	2,345,204	682,929	78,108,945
Accumulated depreciation and impairment	—	(7,533,863)	(43,894,154)	(4,736,326)	(1,833,481)	—	(57,997,824)
	452,738	4,343,556	13,282,185	837,990	511,723	682,929	20,111,121


	2022
	Land	Buildings	Machinery and equipment	Tools	Others	Construction in progress and equipment to be inspected	Total
	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000
January 1
Cost	452,738	11,877,419	57,176,339	5,574,316	2,345,204	682,929	78,108,945
Accumulated depreciation and impairment	—	(7,533,863)	(43,894,154)	(4,736,326)	(1,833,481)	—	(57,997,824)
	452,738	4,343,556	13,282,185	837,990	511,723	682,929	20,111,121
January 1	452,738	4,343,556	13,282,185	837,990	511,723	682,929	20,111,121
Additions	—	3,780	6,748	636	—	4,907,318	4,918,482
Disposals	—	—	(46,084)	(2,597)	—	—	(48,681)
Reclassifications	—	1,503,432	2,603,381	685,481	294,765	(5,086,047)	1,012
Depreciation expenses	—	(465,260)	(3,075,191)	(724,813)	(257,817)	—	(4,523,081)
Impairment losses	—	—	(12,721)	—	—	—	(12,721)
Exchange adjustment	—	—	50	—	23	—	73
December 31	452,738	5,385,508	12,758,368	796,697	548,694	504,200	20,446,205
December 31
Cost	452,738	13,379,852	59,197,255	5,716,357	2,615,959	504,200	81,866,361
Accumulated depreciation and impairment	—	(7,994,344)	(46,438,887)	(4,919,660)	(2,067,265)	—	(61,420,156)
	452,738	5,385,508	12,758,368	796,697	548,694	504,200	20,446,205


	2023
	Land	Buildings	Machinery and equipment	Tools	Others	Construction in progress and equipment to be inspected	Total
	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000	NT$000
January 1
Cost	452,738	13,379,852	59,197,255	5,716,357	2,615,959	504,200	81,866,361
Accumulated depreciation and impairment	—	(7,994,344)	(46,438,887)	(4,919,660)	(2,067,265)	—	(61,420,156)
	452,738	5,385,508	12,758,368	796,697	548,694	504,200	20,446,205
January 1	452,738	5,385,508	12,758,368	796,697	548,694	504,200	20,446,205
Additions	—	1,303	5,579	291	1,376	3,219,922	3,228,471
Disposals	—	—	(16,574)	(11,038)	—	—	(27,612)
Reclassifications	2,000	469,597	1,787,140	586,090	226,610	(3,071,437)	—
Depreciation expenses	—	(557,187)	(3,043,504)	(635,227)	(262,388)	—	(4,498,306)
Impairment losses	—	—	(9,236)	—	—	—	(9,236)
Exchange adjustment	—	—	—	—	(19)	—	(19)
December 31	454,738	5,299,221	11,481,773	736,813	514,273	652,685	19,139,503
December 31
Cost	454,738	13,850,418	60,650,428	5,959,251	2,774,055	652,685	84,341,575
Accumulated depreciation and impairment	—	(8,551,197)	(49,168,655)	(5,222,438)	(2,259,782)	—	(65,202,072)
	454,738	5,299,221	11,481,773	736,813	514,273	652,685	19,139,503

Amount of borrowing costs capitalized as part of property, plant and equipment and the range of the interest rates for such capitalization are as follows:


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Amount of interest capitalized	11,193	10,856	7,692
Range of the interest rates for capitalization	1.1358%	1.0094%	1.4588%

Information about the property, plant and equipment that were pledged to others as collaterals is provided in Note 36.

Significant contingent liabilities and unrecognized contract commitments (Tables)

12 Months Ended

Dec. 31, 2023

Capital commitments [abstract]

Capital Expenditures that are Contracted for, but not Provided for

Capital expenditures that are contracted for, but not provided for are as follows:


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Property, plant and equipment, net	1,703,841	1,940,740

Consolidated Statements of Comprehensive Income $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($) $ / shares	Dec. 31, 2023 USD ($) $ / shares	Dec. 31, 2022 TWD ($) $ / shares	Dec. 31, 2021 TWD ($) $ / shares
Consolidated statements of comprehensive income [Line Items]
Revenue	$ 21,356,228	$ 697,460	$ 23,517,064	$ 27,400,035
Cost of revenue	(17,806,803)	(581,542)	(18,605,007)	(20,146,057)
Gross profit	3,549,425	115,918	4,912,057	7,253,978
Sales and marketing expenses	(135,661)	(4,431)	(128,029)	(73,928)
General and administrative expenses	(497,742)	(16,255)	(538,684)	(604,029)
Research and development expenses	(1,093,513)	(35,712)	(1,158,598)	(1,139,219)
Other income (expenses), net	85,943	2,807	129,933	125,587
Operating profit	1,908,452	62,327	3,216,679	5,562,389
Interest income	193,189	6,309	57,199	9,980
Other income	77,583	2,534	66,991	34,496
Other gains and losses	135,501	4,425	386,567	(65,829)
Finance costs	(266,390)	(8,700)	(153,279)	(131,184)
Share of profit of associates and joint ventures accounted for using equity method	219,891	7,182	453,715	625,733
Profit before income tax	2,268,226	74,077	4,027,872	6,035,585
Income tax expense	(300,661)	(9,819)	(588,175)	(1,098,318)
Profit for the year	1,967,565	64,258	3,439,697	4,937,267
Other comprehensive income (loss):
(Loss) profit on remeasurements of defined benefit plans	10,699	350	222,234	(14,999)
Unrealized gain (loss) on valuation of equity instruments at fair value through other comprehensive income	(217,785)	(7,113)	(46,419)	122,514
Share of other comprehensive income (loss) of associates and joint ventures accounted for using equity method that will not be reclassified to profit or loss	12,993	424	(28,254)	28,843
Income tax effect on components that will not be reclassified to profit or loss	49,498	1,617	(31,888)	(27,460)
Components of other comprehensive income (loss) that will not be reclassified to profit or loss	(144,595)	(4,722)	115,673	108,898
Exchange differences on translation of foreign operations	16,713	546	68,656	(24,695)
Equity directly related to non-current assets held for sale	(43,094)	(1,408)
Components of other comprehensive (loss) income that will be reclassified to profit or loss	(26,381)	(862)	68,656	(24,695)
Other comprehensive income (loss), net of income tax	(170,976)	(5,584)	184,329	84,203
Total comprehensive income (loss) for the year	$ 1,796,589	$ 58,674	$ 3,624,026	$ 5,021,470
Ordinary shares [member]
Other comprehensive income (loss):
Earnings per share - basic \| (per share)	$ 2.71	$ 0.09	$ 4.73	$ 6.79
Earnings per share - diluted \| (per share)	2.68	0.09	4.63	6.65
American depositary share (each representing 20 common shares) [member]
Other comprehensive income (loss):
Earnings per share - basic \| (per share)	54.11	1.77	94.6	135.78
Earnings per share - diluted \| (per share)	$ 53.54	$ 1.75	$ 92.63	$ 132.93

Employee benefit expenses - Summary of Employee benefit expenses (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Classes of employee benefits expense [abstract]
Salaries	$ 4,741,380	$ 5,302,234	$ 5,632,219
Directors' remuneration	23,980	28,621	40,164
Labor and health insurance	432,568	449,223	424,901
Pension	195,359	205,671	200,014
Other personnel expenses	442,781	480,554	460,590
Total Employee benefit expenses	$ 5,836,068	$ 6,466,303	$ 6,757,888

Employee benefit expenses (Tables)

12 Months Ended

Dec. 31, 2023

Employee benefit expenses [Abstract]

Summary of Employee benefit expenses


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Salaries	5,632,219	5,302,234	4,741,380
Directors’ remuneration	40,164	28,621	23,980
Labor and health insurance	424,901	449,223	432,568
Pension	200,014	205,671	195,359
Other personnel expenses	460,590	480,554	442,781
	6,757,888	6,466,303	5,836,068

For the year of 2022, employees’ compensation and directors’ remuneration recognized were consistent with the amounts resolved in the Board of Directors’ meeting.

Other gains and losses (Tables)

12 Months Ended

Dec. 31, 2023

Disclosure of Other gains and losses [Abstract]

Summary of Other gains and losses


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Foreign exchange (losses) gains, net	(89,152)	448,097	78,170
Gain (loss) on valuation of financial assets at fair value through profit or loss	15,262	(69,404)	39,254
Reimbursement of ADSs service charge	2,284	2,412	2,121
Compensation income	1,524	174	20
Others	4,253	5,288	15,936
	(65,829)	386,567	135,501

Changes in liabilities from financing activities (Tables)

12 Months Ended

Dec. 31, 2023

Disclosure of reconciliation of liabilities arising from financing activities [abstract]

Reconciliation of Liabilities Arising from Financing Activities


	2021
	Short-term bank loans	Long-term bank loans (including current portion)	Guarantee deposits	Lease liabilities	Total liabilities from financing activities
	NT$000	NT$000	NT$000	NT$000	NT$000
January 1	—	7,733,565	21,670	870,495	8,625,730
Changes in cash flow from financing activities	731,751	1,652,332	(45)	(289,668)	2,094,370
Adjustment of right-of-use assets	—	—	—	255,179	255,179
Amortization of loan fees	—	7,646	—	—	7,646
Amortization of interest expense	—	19,822	—	15,245	35,067
December 31	731,751	9,413,365	21,625	851,251	11,017,992


	2022
	Short-term bank loans	Long-term bank loans (including current portion)	Guarantee deposits	Lease liabilities	Total liabilities from financing activities
	NT$000	NT$000	NT$000	NT$000	NT$000
January 1	731,751	9,413,365	21,625	851,251	11,017,992
Changes in cash flow from financing activities	(731,751)	4,513,672	(25)	(237,869)	3,544,027
Adjustment of right-of-use assets	—	—	—	292,464	292,464
Amortization of loan fees	—	10,026	—	—	10,026
Amortization of interest expense	—	30,738	—	14,556	45,294
December 31	—	13,967,801	21,600	920,402	14,909,803


	2023
	Long-term bank loans (including current portion)	Guarantee deposits	Lease liabilities	Total liabilities from financing activities
	NT$000	NT$000	NT$000	NT$000
January 1	13,967,801	21,600	920,402	14,909,803
Changes in cash flow from financing activities	907,306	(365)	(293,383)	613,558
Adjustment of right-of-use assets	—	—	419,625	419,625
Amortization of interest expense	36,612	—	18,757	55,369
December 31	14,911,719	21,235	1,065,401	15,998,355

Interest income

12 Months Ended

Dec. 31, 2023

Disclosure of Interest Income [Abstract]

Interest income

25.

Interest income


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Bank deposits	8,772	56,612	191,265
Financial assets at amortized cost	1,187	587	1,861
Other interest income	21	—	63
	9,980	57,199	193,189

Supplemental cash flow information

12 Months Ended

Dec. 31, 2023

Statement of cash flows [abstract]

Supplemental cash flow information

33.

Supplemental cash flow information

Partial cash paid for investing activities

Property, plant and equipment


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Purchase of property, plant and equipment	6,552,702	4,918,482	3,228,471
Add: Beginning balance of payable to equipment suppliers	1,145,359	1,816,555	1,405,931
Less: Ending balance of payable to equipment suppliers	(1,816,555)	(1,405,931)	(1,196,181)
Less: Ending balance of payable to equipment suppliers – related parties	—	—	(58,549)
Less: Transfer from other non-current assets	—	(629,737)	(305,791)
Cash paid during the year	5,881,506	4,699,369	3,073,881

Leasing arrangements - leasee

12 Months Ended

Dec. 31, 2023

Presentation of leases for lessee [abstract]

Leasing arrangements - leasee

15.

Leasing arrangements – lessee

The Group leases various assets, including land, buildings, machinery and equipment, and others. Lease contracts are typically made for periods of 2 to 30 years. For machinery and equipment, lease contracts are between 2 to 3 years. For land, lease contracts are between 10 to 30 years. Lease terms are negotiated on an individual basis and contain a wide range of different terms and conditions. The lease contracts do not impose covenants, but leased assets may not be used as security for borrowing purposes.

The carrying amount of right-of-use assets and the depreciation expenses are as follows:


	Carrying amount
	December 31, 2022	December 31, 2023
	NT$000	NT$000
Land	630,969	615,385
Buildings	8,214	7,723
Machinery and equipment	257,196	411,809
Others	2,613	2,585
	898,992	1,037,502


	Depreciation expenses
	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Land	20,486	21,904	21,524
Buildings	9,870	10,861	11,738
Machinery and equipment	247,090	194,059	245,304
Others	1,634	1,997	2,461
	279,080	228,821	281,027

For the years ended December 31, 2022 and 2023, additions to right-of-use assets were NT$308,550 thousand and NT$419,625 thousand, respectively.

The information on profit or loss accounts relating to lease contracts is as follows:


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Items affecting profit or loss
Interest expense on lease liabilities	15,245	14,556	18,757
Expense on short-term lease contracts	143,791	95,213	55,944

For the years ended December 31, 2021, 2022 and 2023, the Group’s total cash outflow for leases were NT$448,290 thousand, NT$333,133 thousand and NT$351,063 thousand, respectively.

Property, Plant and Equipment, Net - Summary of Property, Plant and Equipment, Net (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	$ 20,446,205		$ 20,111,121	$ 17,994,686
Additions	3,228,471		4,918,482	6,552,702
Disposals	(27,612)		(48,681)	(76,375)
Reclassifications	0		1,012	0
Depreciation expenses	(4,498,306)		(4,523,081)	(4,355,032)
Impairment losses	(9,236)	$ (302)	(12,721)	(4,843)
Exchange adjustments	(19)		73	(17)
Ending Balance	19,139,503	$ 625,065	20,446,205	20,111,121
Land [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	452,738		452,738	452,738
Additions	0		0	0
Disposals	0		0	0
Reclassifications	2,000		0	0
Depreciation expenses	0		0	0
Impairment losses	0		0	0
Exchange adjustments	0		0	0
Ending Balance	454,738		452,738	452,738
Buildings [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	5,385,508		4,343,556	4,092,286
Additions	1,303		3,780	1,345
Disposals	0		0	0
Reclassifications	469,597		1,503,432	673,208
Depreciation expenses	(557,187)		(465,260)	(423,283)
Impairment losses	0		0	0
Exchange adjustments	0		0	0
Ending Balance	5,299,221		5,385,508	4,343,556
Machinery and equipment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	12,758,368		13,282,185	11,348,297
Additions	5,579		6,748	11,829
Disposals	(16,574)		(46,084)	(66,873)
Reclassifications	1,787,140		2,603,381	4,890,400
Depreciation expenses	(3,043,504)		(3,075,191)	(2,896,612)
Impairment losses	(9,236)		(12,721)	(4,843)
Exchange adjustments	0		50	(13)
Ending Balance	11,481,773		12,758,368	13,282,185
Tools [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	796,697		837,990	952,361
Additions	291		636	407
Disposals	(11,038)		(2,597)	(9,502)
Reclassifications	586,090		685,481	690,346
Depreciation expenses	(635,227)		(724,813)	(795,622)
Impairment losses	0		0	0
Exchange adjustments	0		0	0
Ending Balance	736,813		796,697	837,990
Other [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	548,694		511,723	509,397
Additions	1,376		0	189
Disposals	0		0	0
Reclassifications	226,610		294,765	241,656
Depreciation expenses	(262,388)		(257,817)	(239,515)
Impairment losses	0		0	0
Exchange adjustments	(19)		23	(4)
Ending Balance	514,273		548,694	511,723
Construction in progress and equipment to be inspected [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	504,200		682,929	639,607
Additions	3,219,922		4,907,318	6,538,932
Disposals	0		0	0
Reclassifications	(3,071,437)		(5,086,047)	(6,495,610)
Depreciation expenses	0		0	0
Impairment losses	0		0	0
Exchange adjustments	0		0	0
Ending Balance	652,685		504,200	682,929
Gross carrying amount [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	81,866,361		78,108,945	73,187,794
Ending Balance	84,341,575		81,866,361	78,108,945
Gross carrying amount [member] \| Land [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	452,738		452,738	452,738
Ending Balance	454,738		452,738	452,738
Gross carrying amount [member] \| Buildings [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	13,379,852		11,877,419	11,212,129
Ending Balance	13,850,418		13,379,852	11,877,419
Gross carrying amount [member] \| Machinery and equipment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	59,197,255		57,176,339	53,246,474
Ending Balance	60,650,428		59,197,255	57,176,339
Gross carrying amount [member] \| Tools [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	5,716,357		5,574,316	5,451,547
Ending Balance	5,959,251		5,716,357	5,574,316
Gross carrying amount [member] \| Other [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	2,615,959		2,345,204	2,185,299
Ending Balance	2,774,055		2,615,959	2,345,204
Gross carrying amount [member] \| Construction in progress and equipment to be inspected [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	504,200		682,929	639,607
Ending Balance	652,685		504,200	682,929
Accumulated depreciation and impairment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	(61,420,156)		(57,997,824)	(55,193,108)
Ending Balance	(65,202,072)		(61,420,156)	(57,997,824)
Accumulated depreciation and impairment [member] \| Land [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	0		0	0
Ending Balance	0		0	0
Accumulated depreciation and impairment [member] \| Buildings [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	(7,994,344)		(7,533,863)	(7,119,843)
Ending Balance	(8,551,197)		(7,994,344)	(7,533,863)
Accumulated depreciation and impairment [member] \| Machinery and equipment [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	(46,438,887)		(43,894,154)	(41,898,177)
Ending Balance	(49,168,655)		(46,438,887)	(43,894,154)
Accumulated depreciation and impairment [member] \| Tools [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	(4,919,660)		(4,736,326)	(4,499,186)
Ending Balance	(5,222,438)		(4,919,660)	(4,736,326)
Accumulated depreciation and impairment [member] \| Other [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	(2,067,265)		(1,833,481)	(1,675,902)
Ending Balance	(2,259,782)		(2,067,265)	(1,833,481)
Accumulated depreciation and impairment [member] \| Construction in progress and equipment to be inspected [member]
Disclosure of detailed information about property, plant and equipment [Line Items]
Beginning Balance	0		0	0
Ending Balance	$ 0		$ 0	$ 0

Financial Risk Management and Fair Values of Financial Instruments - Additional Information (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of detailed information about financial instruments [Line Items]
Realized and unrealized gain and loss arising from significant foreign exchange variation	$ 78,170	$ 448,097	$ (89,152)
Adjustments to interest rate	1.00%	1.00%	1.00%
General increase or decrease of 100 basis points (1%) in interest rates [member]
Disclosure of detailed information about financial instruments [Line Items]
Estimated decrease or increase in the Group's profit and equity based on an increase or decrease in the interest rates	$ 149,723	$ 140,561	$ 102,489
Equity price risk [member]
Disclosure of detailed information about financial instruments [Line Items]
Estimated decrease or increase in the Group's profit and equity based on an increase or decrease in the interest rates	$ 427	$ 1,282	$ 3,600
Percentage of increase or decrease in price of equity securities	1.00%	1.00%	1.00%

Pensions - Defined Benefit Plans Amounts Recognized in Statements of Financial Position (Detail) - TWD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Surplus (deficit) in plan [abstract]
Present value of defined benefit obligations	$ (744,191)	$ (759,548)
Fair value of plan assets	516,854	500,333
Net defined benefit liability	$ (227,337)	$ (259,215)	$ (503,288)	$ (511,651)

Income Tax Expense - Details of Deferred Tax Assets (Liabilities) (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2020 TWD ($)
Disclosure of the detail of deferred tax assets and liabilities [line items]
Deferred tax assets	$ 163,282	$ 159,286	$ 180,598	$ 5,333	$ 185,691
Deferred tax liabilities	(127,193)	(201,741)	(278,177)	$ (4,154)	$ (310,427)
Deferred tax assets unrealized loss on inventories [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	21,126	24,317	15,963
Recognized in profit or loss	16,127	(3,191)	8,354
Ending balance	37,253	21,126	24,317
Property, plant and equipment, deferred tax assets [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	38,894	36,636	36,401
Ending balance	40,741	38,894	36,636
Provisions [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	12,859	2,849	2,678
Recognized in profit or loss	1,518	10,010	171
Ending balance	14,377	12,859	2,849
Deferred tax assets deferred revenue [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	8,132	14,638	21,144
Recognized in profit or loss	(6,506)	(6,506)	(6,506)
Ending balance	1,626	8,132	14,638
Net defined benefit liability [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	48,433	97,248	98,921
Recognized in profit or loss	(4,236)	(4,368)	(4,672)
Recognized in other comprehensive income	(2,140)	(44,447)	2,999
Ending balance	42,057	48,433	97,248
Unrealized exchange losses deferred tax assets [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	24,217	2,161	9,915
Recognized in profit or loss	(6,032)	22,056	(7,754)
Ending balance	18,185	24,217	2,161
Others [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	5,625	2,749	669
Recognized in profit or loss	3,418	2,876	2,080
Ending balance	9,043	5,625	2,749
Deferred tax asset [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	159,286	180,598	185,691
Recognized in profit or loss	6,136	23,135	(8,092)
Recognized in other comprehensive income	(2,140)	(44,447)	2,999
Ending balance	163,282	159,286	180,598
Property, plant and equipment, deferred tax liabilities [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	(116,974)	(192,687)	(255,484)
Recognized in profit or loss	42,142	75,713	62,797
Ending balance	(74,832)	(116,974)	(192,687)
Property, plant and equipment [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Recognized in profit or loss	1,847	2,258	235
Financial assets at fair value through other comprehensive income [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	(72,843)	(85,402)	(54,943)
Recognized in other comprehensive income	51,638	12,559	(30,459)
Ending balance	(21,205)	(72,843)	(85,402)
Gain on investment in associates [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	(11,923)
Recognized in profit or loss	(19,228)	(11,923)
Ending balance	(31,151)	(11,923)
Others [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	(1)	(88)
Recognized in profit or loss	(4)	87	(88)
Ending balance	(5)	(1)	(88)
Deferred tax liabilities [member]
Disclosure of the detail of deferred tax assets and liabilities [line items]
Beginning balance	(201,741)	(278,177)	(310,427)
Recognized in profit or loss	22,910	63,877	62,709
Recognized in other comprehensive income	51,638	12,559	(30,459)
Ending balance	$ (127,193)	$ (201,741)	$ (278,177)

Segment Information - Financial Segment Information for Operating Segments (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Revenue
Revenue	$ 21,356,228	$ 697,460	$ 23,517,064	$ 27,400,035
Operating profit (loss)	1,908,452	62,327	3,216,679	5,562,389
Depreciation expenses	(4,779,333)		(4,751,902)	(4,634,112)
Share of profit of associates	219,891	7,182	453,715	625,733
Interest income	193,189	$ 6,309	57,199	9,980
Interest expense	(265,957)		(142,439)	(120,998)
Purchase of property, plant and equipment	3,228,471		4,918,482	6,552,702
External [member]
Revenue
Revenue	21,356,228		23,517,064	27,400,035
Operating segments [member] \| Testing [member]
Revenue
Revenue	4,394,726		5,243,997	5,899,600
Operating profit (loss)	514,707		1,253,477	1,814,021
Depreciation expenses	(1,065,689)		(1,042,455)	(921,999)
Purchase of property, plant and equipment	749,158		1,086,682	1,841,359
Operating segments [member] \| Testing [member] \| External [member]
Revenue
Revenue	4,394,726		5,243,997	5,899,600
Operating segments [member] \| Assembly [member]
Revenue
Revenue	4,629,430		6,705,898	7,963,714
Operating profit (loss)	(1,180,481)		(93,585)	857,304
Depreciation expenses	(722,462)		(694,835)	(576,138)
Purchase of property, plant and equipment	568,289		957,790	1,553,475
Operating segments [member] \| Assembly [member] \| External [member]
Revenue
Revenue	4,629,430		6,705,898	7,963,714
Operating segments [member] \| LCDD [member]
Revenue
Revenue	7,821,640		7,288,642	8,211,099
Operating profit (loss)	2,058,285		1,795,741	2,336,394
Depreciation expenses	(2,547,253)		(2,505,297)	(2,579,150)
Purchase of property, plant and equipment	1,756,590		2,677,489	2,748,697
Operating segments [member] \| LCDD [member] \| External [member]
Revenue
Revenue	7,821,640		7,288,642	8,211,099
Operating segments [member] \| Bumping [member]
Revenue
Revenue	4,510,432		4,278,527	5,325,622
Operating profit (loss)	522,386		268,159	561,642
Depreciation expenses	(435,709)		(500,863)	(549,020)
Purchase of property, plant and equipment	152,908		196,521	408,751
Operating segments [member] \| Bumping [member] \| External [member]
Revenue
Revenue	4,510,432		4,278,527	5,325,622
Operating segments [member] \| Others [member]
Revenue
Revenue	59,481		50,600	43,808
Operating profit (loss)	(6,194)		(6,821)	(6,987)
Depreciation expenses	(8,220)		(8,452)	(7,805)
Share of profit of associates	420,393		884,555	1,211,177
Interest income	193,189		57,199	9,980
Interest expense	(265,957)		(142,439)	(120,998)
Purchase of property, plant and equipment	1,526			420
Operating segments [member] \| Others [member] \| Intersegment [member]
Revenue
Revenue	59,481		50,600	43,808
Elimination [member]
Revenue
Revenue	(59,481)		(50,600)	(43,808)
Operating profit (loss)	(251)		(292)	15
Share of profit of associates	(200,502)		(430,840)	585,444
Elimination [member] \| Intersegment [member]
Revenue
Revenue	$ (59,481)		$ (50,600)	$ (43,808)

Expenses by nature (Tables)

12 Months Ended

Dec. 31, 2023

Analysis of income and expense [abstract]

Summary of Expenses by nature


	Year ended December 31,
	2021	2022	2023
	NT$000	NT$000	NT$000
Raw materials and supplies used	5,518,145	4,512,527	3,991,490
Employee benefit expenses	6,757,888	6,466,303	5,836,068
Depreciation expenses	4,634,112	4,751,902	4,779,333
Others	5,053,088	4,699,586	4,926,828
	21,963,233	20,430,318	19,533,719

Summary of material accounting policies (Policies)

12 Months Ended

Dec. 31, 2023

Summary Of Material Accounting Policies [Abstract]

Statement of compliance

The consolidated financial statements of the Group have been prepared in accordance with IFRSs as issued by the IASB.

Basis of preparation

(a)

Except for the following items, the consolidated financial statements have been prepared under the historical cost convention:

Financial assets at fair value through profit or loss (including derivative instruments).

ii)

Financial assets at fair value through other comprehensive income.

iii)

Defined benefit liabilities were recognized based on the net amount of pension fund assets less the present value of benefit obligation.

(b)

(c)

These consolidated financial statements are presented in New Taiwan dollars (“NT$”), which is the Company’s functional currency.

Basis of consolidation

(a)

Basis for preparation of consolidated financial statements:

ii)

iii)

iv)

(b)

Subsidiaries included in the consolidated financial statements:


				Percentage of Ownership (%)
				December 31,
Name of investor	Name of investee	Main business	Location	2022	2023
The Company	ChipMOS U.S.A., Inc. (“ChipMOS USA”)	Marketing of semiconductors and electronic related products	San Jose, USA	100	100
The Company	ChipMOS TECHNOLOGIES (BVI) LTD. (“ChipMOS BVI”)	Holding company	British Virgin Islands	100	100
ChipMOS BVI	ChipMOS SEMICONDUCTORS (Shanghai) LTD. (“ChipMOS Shanghai”)	Marketing of semiconductors and electronic related products	Shanghai, People’s Republic of China (“PRC”)	100	100

(c)

Subsidiaries not included in the consolidated financial statements: None.

(d)

Adjustments for subsidiaries with different statements of financial position dates: Not applicable.

(e)

No significant restrictions on the ability of subsidiaries to transfer funds to parent company.

(f)

Subsidiaries that have non-controlling interests that are material to the Group: None.

Foreign currency translation

(a)

Foreign currency transactions and balances

ii)

iii)

iv)

All foreign exchange differences are presented in the statement of comprehensive income under “Other gains and losses” by the nature of transactions.

(b)

Translation of foreign operations

Assets and liabilities for each statements of financial position are translated at the exchange rates prevailing at the statements of financial position date;

ii)

Income and expenses for each statement of comprehensive income are translated at average exchange rates of that period; and

All exchange differences are recognized in other comprehensive income.

Classification of current and non-current assets and liabilities

(a)

Assets that meet one of the following criteria are classified as current assets:

Assets arising from operating activities that are expected to be realized, or are intended to be sold or consumed within the normal operating cycle;

ii)

Assets held mainly for trading purposes;

iii)

Assets that are expected to be realized within 12 months from the statements of financial position date;

iv)

All assets that do not meet the above criteria are classified as non-current assets.

(b)

Liabilities that meet one of the following criteria are classified as current liabilities:

Liabilities that are expected to be settled within the normal operating cycle;

ii)

Liabilities arising mainly from trading activities;

iii)

Liabilities that are to be settled within 12 months from the statements of financial position date;

iv)

All liabilities that do not meet the above criteria are classified as non-current liabilities.

Cash equivalents

Financial assets at fair value through profit or loss

(a)

Financial assets at fair value through profit or loss are financial assets that are not measured at amortized cost or fair value through other comprehensive income.

(b)

On a regular way purchase or sale basis, financial assets at fair value through profit or loss are recognized and derecognized using settlement date accounting.

(c)

(d)

Financial assets at fair value through other comprehensive income

(a)

(b)

On a regular way purchase or sale basis, financial assets at fair value through other comprehensive income are recognized and derecognized using settlement date accounting.

(c)

At initial recognition, the Group measures the financial assets at fair value plus transaction costs. The Group subsequently measures the financial assets at fair value:

Financial assets at amortized cost

(a)

Financial assets at amortized cost are those that meet all of the following criteria:

The objective of the Group’s business model is achieved by collecting contractual cash flows.

ii)

The financial assets’ contractual cash flows represent solely payments of principal and interest.

(b)

The Group’s time deposits which do not fall under cash equivalents are those with a short maturity period and are measured at initial investment amount as the effect of discounting is immaterial.

Accounts receivable

(a)

Accounts receivable entitle the Group a legal right to receive consideration in exchange for transferred goods or rendered services.

The short-term accounts receivable without bearing interest are subsequently measured at initial invoice amount as the effect of discounting is immaterial.

Impairment of financial assets

Derecognition of financial assets

The Group derecognizes a financial asset when the contractual rights to receive the cash flows from the financial asset have expired.

Inventories

Non-current assets held for sale

Investments accounted for using equity method – associates

(a)

(b)

(c)

(d)

(e)

(f)

Property, plant and equipment

(a)

Property, plant and equipment are initially recorded at cost. Borrowing costs incurred during the construction period are capitalized.

(b)

(c)

(d)


Buildings		1 to 51 years
Machinery and equipment		1 to 20 years
Tools		1 to 4 years
Others		1 to 7 years

Leasing arrangements (lessee) – right-of-use assets / lease liabilities

(a)

(b)

Lease liabilities include the net present value of the remaining lease payments at the commencement date, discounted using the incremental borrowing interest rate.

Lease payments are comprised of the following:

Fixed payments, less any lease incentives receivable;

ii)

The exercise price of a purchase option, if the lessee is reasonably certain to exercise that option.

Impairment of non-financial assets

Loans

Accounts and notes payable

(a)

Accounts payable are liabilities for purchases of raw materials, goods or services and notes payable are those resulting from operating and non-operating activities.

(b)

The short-term accounts and notes payable without bearing interest are subsequently measured at initial invoice amount as the effect of discounting is immaterial.

Derecognition of financial liabilities

A financial liability is derecognized when the obligation specified in the contract is either discharged or cancelled or expires.

Provisions for deficiency compensation

Employee benefits

(a)

Short-term employee benefits

(b)

Pensions

Defined contribution plans

ii)

Defined benefit plans

Remeasurements arising on defined benefit plans are recognized in other comprehensive income in the period in which they arise and are recorded as retained earnings.

Past service costs are recognized immediately in profit or loss.

(c)

Termination benefits

(d)

Employees’ compensation and directors’ remuneration

Income tax

(a)

(b)

(c)

(d)

(e)

Capital stock

(a)

Ordinary shares are classified as equity. Incremental costs directly attributable to the issue of new shares in net proceeds of tax are shown in equity as a deduction.

Dividends

Revenue recognition

aa)

Revenue recognition

(a)

Customer controls the provided raw materials and the Group receives the instruction from the customer on providing assembly and testing services and subsequent treatments.

ii)

The Group provides assembly and testing services to create or enhance an asset which is solely provided and controlled by the customer. The Group has no right to transfer the asset for another use.

(b)

Government grants

bb)

Government grants

Operating segments

cc)

Operating segments

Critical accounting judgments, estimates and key sources of assumption uncertainty

dd)

Critical accounting judgments, estimates and key sources of assumption uncertainty

Critical accounting estimates and assumptions – Revenue recognition

Non-current financial assets at fair value through other comprehensive income

12 Months Ended

Dec. 31, 2023

Non-current financial assets at fair value through other comprehensive income [abstract]

Non-current financial assets at fair value through other comprehensive income

11.

Non-current financial assets at fair value through other comprehensive income


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Designation of equity instruments
Foreign unlisted stocks	38,534	38,534
Valuation adjustment	299,568	81,783
	338,102	120,317

Based on the Group’s business model, the foreign unlisted stocks held for strategic investments were elected to classify as Financial assets at fair value through other comprehensive income. As of December 31, 2022 and 2023, the fair value of aforementioned investments is the carrying amount at the end of each reporting period.

Amounts recognized in other comprehensive income in relation to the financial assets at fair value through other comprehensive income are listed below:

No financial assets at fair value through other comprehensive income were pledged to others.

In April 2023, the Company acquired 1,000 thousand ordinary shares of Daypower Energy Co., Ltd. (“Daypower Energy”) in the amount of NT$12,500 thousand, representing 10% of shareholding and was recorded as financial assets at fair value through other comprehensive income. Subsequently, in August 2023, the Company participated in the re-election of the directors of Daypower Energy and obtained significant influence by holding one seat in Daypower Energy’s Board of Directors. As a result, the Company reclassified the investment as investment accounted for using equity method from financial assets at fair value through other comprehensive income. Information related to Daypower Energy investment is provided in Note 12.

Information about fair value measurement is provided in Note 41 b).

Capital stock - Additional Information (Detail) $ / shares in Units, $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($) $ / shares shares	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 TWD ($) shares	Dec. 31, 2021 shares
Disclosure of classes of share capital [line items]
Ordinary shares par value \| $ / shares	$ 10
Number of shares outstanding	727,240,000	727,240,000	727,240,000	727,240,000
Authorised capital \| $	$ 9,700,000
Number of shares authorized	970,000,000	970,000,000
Paid in capital	$ 7,272,401	$ 237,505	$ 7,272,401
Ordinary shares [member]
Disclosure of classes of share capital [line items]
Number of shares outstanding	84,699,000	84,699,000
American depositary shares [member]
Disclosure of classes of share capital [line items]
Number of shares represented by each unit of ADS	20
Number of shares outstanding	4,234,970	4,234,970

Long-term bank loans (Tables)

12 Months Ended

Dec. 31, 2023

Borrowings [abstract]

Summary of Bank Loans


Type of loans	Period and payment term	December 31, 2022	December 31, 2023
		NT$000	NT$000
Government granted bank loans	Borrowing period is from March 11, 2020 to October 15, 2032; interest is repayable monthly; principal is repayable monthly from March 15, 2023	14,056,131	14,972,311
Less: Unamortized interest on government granted bank loans		(88,330)	(60,592)
Less: Current portion (fee included)		(1,522,917)	(2,263,718)
		12,444,884	12,648,001
Interest rate range		1.075%~1.625%	1.2%~1.75%
Unused credit lines of long-term bank loans
NT$000		9,671,868	7,232,770

Other Payables (Tables)

12 Months Ended

Dec. 31, 2023

Trade and other current payables [abstract]

Summary of Other Payables


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Payable to equipment suppliers	1,405,931	1,196,181
Salaries and bonuses payable	1,002,577	994,651
Employees’ compensation payable	447,303	250,181
Pension payable	16,541	16,825
Directors’ remuneration payable	11,182	6,255
Interest payable	7,768	9,625
Other expense payable	905,179	1,005,327
	3,796,481	3,479,045

Capital surplus (Tables)

12 Months Ended

Dec. 31, 2023

Capital surplus [Abstract]

Summary of Capital Surplus


	2021
	Share premium	Others	Total
	NT$000	NT$000	NT$000
January 1	6,043,483	7,304	6,050,787
Changes in associates accounted for using equity method	—	4,834	4,834
December 31	6,043,483	12,138	6,055,621


	2022
	Share premium	Others	Total
	NT$000	NT$000	NT$000
January 1	6,043,483	12,138	6,055,621
Changes in associates accounted for using equity method	—	152	152
December 31	6,043,483	12,290	6,055,773


	2023
	Share premium	Others	Total
	NT$000	NT$000	NT$000
January 1	6,043,483	12,290	6,055,773
December 31	6,043,483	12,290	6,055,773

Revenue - Summary of Revenue From Contracts with Customers (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Receivables from contracts with customers [abstract]
Revenue from contracts with customers	$ 21,356,228	$ 23,517,064	$ 27,400,035

Other Income - Summary of Other income (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Analysis of other income [Abstract]
Rental income	$ 48,264	$ 35,848	$ 17,326
Grant income	22,727	21,327	12,480
Dividend income	6,592	9,816	4,690
Other non-operating income (expenses), net	$ 77,583	$ 66,991	$ 34,496

Non-current assets held for sale - Summary of Assets Held for Sale (Details) - Dec. 31, 2023 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Disclosure of subsidiaries [line items]
Investment accounted for using equity method in Unimos Shanghai	$ 4,278,658	$ 139,734
Unimos Shanghai [member]
Disclosure of subsidiaries [line items]
Investment accounted for using equity method in Unimos Shanghai	$ 4,278,658

Leasing arrangements - leasee - summary of carrying amount of right-of-use assets and the depreciation expenses (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)	Dec. 31, 2023 USD ($)
Disclosure of quantitative information about right-of-use assets [line items]
Carrying amount	$ 1,037,502	$ 898,992		$ 33,883
Depreciation expenses	281,027	228,821	$ 279,080
Land [member]
Disclosure of quantitative information about right-of-use assets [line items]
Carrying amount	615,385	630,969
Depreciation expenses	21,524	21,904	20,486
Buildings [member]
Disclosure of quantitative information about right-of-use assets [line items]
Carrying amount	7,723	8,214
Depreciation expenses	11,738	10,861	9,870
Machinery and equipment [member]
Disclosure of quantitative information about right-of-use assets [line items]
Carrying amount	411,809	257,196
Depreciation expenses	245,304	194,059	247,090
Others [member]
Disclosure of quantitative information about right-of-use assets [line items]
Carrying amount	2,585	2,613
Depreciation expenses	$ 2,461	$ 1,997	$ 1,634

Other Income (Expenses), Net - Summary of Other Income (Expenses), Net (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2021 TWD ($)
Analysis of income and expense [abstract]
Gain on disposal of property, plant and equipment, net	$ 18,431		$ 74,548	$ 33,935
Gain on disposal of scrapped materials	44,662		35,381	52,254
Gain on disposal of items purchased on behalf of others	12,729		19,107	21,945
Gains from lease modifications			139	891
Impairment loss on property, plant and equipment	(9,236)	$ (302)	(12,721)	(4,843)
Others	19,357		13,479	21,405
Other operating income (expense), Total	$ 85,943	$ 2,807	$ 129,933	$ 125,587

Retained earnings

12 Months Ended

Dec. 31, 2023

Retained earnings [abstract]

Retained earnings

21.

Retained earnings

Under the Company’s Articles of Incorporation, upon the final settlement of accounts, if there is net profit, the Company shall first set aside the tax payable and offset its losses before setting aside a legal capital reserve at 10% of the remaining profit. The Company shall then set aside or reverse the special capital reserve in accordance with the laws and regulations and as requested by the competent authorities. The remaining profit of that fiscal year, as well as the accumulated undistributed profit at the beginning of the same year and the adjusted undistributed profit of the given fiscal year, shall be distributable profit. If there is any surplus distributable profit after the Board of Directors sets aside a reserve based on the Company’s operational needs, such surplus profit may be distributed in full or in part to shareholders as dividends, subject to the approval of the shareholders’ meeting.

The Company’s dividend policy is summarized here. A proposal on the distribution of dividends shall be submitted by the Board of Directors annually to the shareholders’ meeting, and be based on factors such as past years’ profit, the current and future investment environment, the Company’s capital needs, competition in the domestic and foreign markets, and budgets, with an aim to pursuing shareholders’ interests and balancing the dividend distribution and the long-term financial plan of the Company. The distribution of profits of the Company can be made in the form of cash dividends or stock dividends, provided that the cash dividend shall account for at least 10% of the total profit distributed as dividends in the given year.

Except for covering accumulated deficits or issuing new shares or cash to shareholders in proportion to their share ownership, the legal reserve may not be used for any other purpose. The use of the legal reserve for the issuance of shares or cash to shareholders in proportion to their share ownership is permitted, provided that the distribution of the reserve is limited to the portion in excess of 25% of the Company’s paid-in capital.

In accordance with the regulations, the Company must set aside a special reserve from the debit balance on other equity items at the statements of financial position date before distributing earnings. When the debit balance on other equity items is reversed subsequently, the reversed amount may be included in the distributable earnings.

The appropriations of 2020, 2021 and 2022 earnings were resolved in the shareholders’ meeting held on July 12, 2021, May 26, 2022 and May 30, 2023, respectively. The appropriations and dividends per share are as follows:


	2020		2021		2022
	Amount	Cash distribution per share	Amount	Cash distribution per share	Amount	Cash distribution per share
	NT$000	NT$	NT$000	NT$	NT$000	NT$
Legal reserve	232,611		505,482		354,986
Special reserve	(19,802)		—		—
Cash dividend	1,599,928	2.20	3,127,133	4.30	1,672,652	2.30

Non-current assets held for sale (Tables)

12 Months Ended

Dec. 31, 2023

Summary of Assets Held for Sale

Assets held for sale:


		December 31, 2023
		NT$000
Investment accounted for using equity method in Unimos Shanghai		4,278,658

Employee benefit expenses - Additional Information (Detail) - TWD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disclosure of defined benefit plans [Line Items]
Accrued Employee Compensation	$ 250,181	$ 447,303	$ 673,387
Accrued Directors remuneration	$ 6,255	$ 11,182	$ 25,690
Defined benefit pension plan [Member]
Disclosure of defined benefit plans [Line Items]
Employees' compensation distribution rate	10.00%
Director remuneration rate no more than	0.50%

Long-term Bank Loans - Summary of Long-term Bank Loans (Detail) $ in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2023 TWD ($)	Dec. 31, 2022 TWD ($)	Dec. 31, 2023 USD ($)
Disclosure of detailed information about borrowings [Line Items]
Bank loans	$ 14,911,719	$ 13,967,801
Less: Unamortized interest on government granted bank loans	(60,592)	(88,330)
Less: Current portion (fee included)	(2,263,718)	(1,522,917)	$ (73,930)
Syndicated bank loans, excluding current portion	12,648,001	12,444,884	$ 413,063
Long-term bank loans [Member]
Disclosure of detailed information about borrowings [Line Items]
Unused credit lines of long-term bank loans	$ 7,232,770	$ 9,671,868
Gross carrying amount [member] \| Minimum [Member]
Disclosure of detailed information about borrowings [Line Items]
Interest rate range	1.20%	1.075%	1.20%
Gross carrying amount [member] \| Maximum [Member]
Disclosure of detailed information about borrowings [Line Items]
Interest rate range	1.75%	1.625%	1.75%
Gross carrying amount [member] \| Government granted bank loans from March 2020 To October 2032 [Member]
Disclosure of detailed information about borrowings [Line Items]
Bank loans	$ 14,972,311	$ 14,056,131
Period and payment term	Borrowing period is from March 11, 2020 to October 15, 2032; interest is repayable monthly; principal is repayable monthly from March 15, 2023

Financial Risk Management and Fair Values of Financial Instruments - Summary of Qualitative Information and Sensitivity Analysis of Changes in Significant Unobservable Inputs Under Valuation Model Used in Level Fair Value Measurement (Detail) - TWD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Fair value	$ 120,317,000	$ 338,102,000
Non derivative equity instruments [member] \| Foreign unlisted stocks [member]
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Fair value	$ 120,317,000	$ 338,102,000
Valuation technique	Comparable companies	Comparable companies
Non derivative equity instruments [member] \| Foreign unlisted stocks [member] \| Price book value multiple [member]
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Range (weighted average method)	$ 1.64
Relationship of inputs to fair value	The higher the multiple, the higher the fair value
Non derivative equity instruments [member] \| Foreign unlisted stocks [member] \| Enter prise value EBITDA multiple [member]
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Range (weighted average method)	$ 8.23	$ 4.82
Relationship of inputs to fair value	The higher the multiple, the higher the fair value	The higher the multiple, the higher the fair value
Non derivative equity instruments [member] \| Foreign unlisted stocks [member] \| Discount for lack of marketability [member]
Disclosure of significant unobservable inputs used in fair value measurement of equity [line items]
Range (weigted average method)	15.70%	15.80%
Relationship of inputs to fair value	The higher the discount for lack of marketability, the lower the fair value	The higher the discount for lack of marketability, the lower the fair value

Consolidated Statements of Financial Position $ in Thousands, $ in Thousands	Dec. 31, 2023 TWD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 TWD ($)
Current assets
Cash and cash equivalents	$ 12,354,035	$ 403,463	$ 9,896,604
Current financial assets at fair value through profit or loss	42,735	1,396	128,224
Current financial assets at amortized cost	41,066	1,341	98,731
Current contract assets	383,883	12,537	381,358
Accounts receivable, net	5,326,381	173,951	4,381,563
Other receivables	44,576	1,456	131,863
Current tax assets	403	13
Inventories	2,568,648	83,888	3,210,409
Prepayments	120,273	3,928	123,377
Non-current assets held for sale, net	4,278,658	139,734
Total current assets	25,160,658	821,707	18,352,129
Non-current assets
Non-current financial assets at fair value through other comprehensive income	120,317	3,929	338,102
Non-current financial assets at amortized cost	37,411	1,222	37,362
Investments accounted for using equity method	290,542	9,489	4,353,448
Property, plant and equipment, net	19,139,503	625,065	20,446,205
Right-of-use assets	1,037,502	33,883	898,992
Deferred tax assets	163,282	5,333	159,286
Refundable deposits	20,707	676	21,771
Other non-current assets	190,562	6,223	335,650
Total non-current assets	20,999,826	685,820	26,590,816
Total assets	46,160,484	1,507,527	44,942,945
Current liabilities
Notes payable	484	16	132
Accounts payable	784,919	25,634	560,802
Other payables	3,479,045	113,620	3,796,481
Other payables - related parties	58,549	1,912
Current tax liabilities	505,600	16,512	361,770
Current provisions	33,564	1,096	26,643
Current lease liabilities	251,668	8,219	160,955
Long-term bank loans, current portion	2,263,718	73,930	1,522,917
Current refund liabilities	37,667	1,230	37,123
Other current liabilities	23,611	771	22,318
Total current liabilities	7,438,825	242,940	6,489,141
Non-current liabilities
Long-term bank loans	12,648,001	413,063	12,444,884
Deferred tax liabilities	127,193	4,154	201,741
Non-current lease liabilities	813,733	26,575	759,447
Long-term deferred revenue	120,963	3,950	127,657
Net defined benefit liability, non-current	227,337	7,425	259,215
Guarantee deposits	21,235	694	21,600
Total non-current liabilities	13,958,462	455,861	13,814,544
Total liabilities	21,397,287	698,801	20,303,685
Equity attributable to equity holders of the Company
Capital stock	7,272,401	237,505	7,272,401
Capital surplus	6,055,773	197,772	6,055,773
Retained earnings
Legal reserve	2,930,973	95,721	2,575,987
Unappropriated retained earnings	8,455,690	276,149	8,506,816
Other equity interest	48,360	1,579	228,283
Total equity	24,763,197	808,726	24,639,260
Total liabilities and equity	$ 46,160,484	$ 1,507,527	$ 44,942,945

Summary of material accounting policies (Tables)

12 Months Ended

Dec. 31, 2023

Summary Of Material Accounting Policies [Abstract]

Summary of Ownership Interests in Subsidiaries


				Percentage of Ownership (%)
				December 31,
Name of investor	Name of investee	Main business	Location	2022	2023
The Company	ChipMOS U.S.A., Inc. (“ChipMOS USA”)	Marketing of semiconductors and electronic related products	San Jose, USA	100	100
The Company	ChipMOS TECHNOLOGIES (BVI) LTD. (“ChipMOS BVI”)	Holding company	British Virgin Islands	100	100
ChipMOS BVI	ChipMOS SEMICONDUCTORS (Shanghai) LTD. (“ChipMOS Shanghai”)	Marketing of semiconductors and electronic related products	Shanghai, People’s Republic of China (“PRC”)	100	100

Estimated Useful Life for Depreciation of Individual Assets


Buildings		1 to 51 years
Machinery and equipment		1 to 20 years
Tools		1 to 4 years
Others		1 to 7 years

Long-term bank loans

12 Months Ended

Dec. 31, 2023

Borrowings [abstract]

Long-term bank loans

17.

Long-term bank loans


Type of loans	Period and payment term	December 31, 2022	December 31, 2023
		NT$000	NT$000
Government granted bank loans	Borrowing period is from March 11, 2020 to October 15, 2032; interest is repayable monthly; principal is repayable monthly from March 15, 2023	14,056,131	14,972,311
Less: Unamortized interest on government granted bank loans		(88,330)	(60,592)
Less: Current portion (fee included)		(1,522,917)	(2,263,718)
		12,444,884	12,648,001
Interest rate range		1.075%~1.625%	1.2%~1.75%
Unused credit lines of long-term bank loans
NT$000		9,671,868	7,232,770

On January 1, 2019, Ministry of Economic Affairs, ROC (“MOEA”) implemented the Action Plan for Welcoming Overseas Taiwanese Businesses to Return to Invest in Taiwan and companies are subsidized with preferential interest loans for qualified investment projects. The Company has obtained the qualification from the MOEA, and signed loan agreements with financial institutions during January 2020 and September 2022 with the line of credit amounted to NT$23.73 billion and terms from seven to ten years. Funding from these loans was used to invest in machineries, equipment and plant expansions and broaden the Company’s working capital.

On May 15, 2018, the Company entered into a syndicated loan with eleven banks in Taiwan, including Taiwan Cooperative Bank, in the amount of NT$12 billion with a term of five years. Funding from this syndicated loan was used to repay the existing debt of financial institutions and broaden the Company’s mid-term working capital. Pursuant to the syndicated loan agreement, the Group is required to maintain certain financial ratios including current ratio, interest protection multiples and debt to equity ratio during the loan periods. The syndicated loan was fully repaid in advance in March 2022.

Information about the items that are pledged to others as collaterals for long-term bank loans is provided in Note 36.

Related Party Transactions - Summary of Significant Related Party Transactions (Detail) - 12 months ended Dec. 31, 2023 $ in Thousands, $ in Thousands	TWD ($)	USD ($)
Disclosure of transactions between related parties [Line Items]
Payable to equipment suppliers	$ 58,549	$ 1,912
Unimos Shanghai [member]
Disclosure of transactions between related parties [Line Items]
Relationship	Associate
JMC ELECTRONICS CO., LTD. [member]
Disclosure of transactions between related parties [Line Items]
Relationship	Associate
Daypower Energy [member]
Disclosure of transactions between related parties [Line Items]
Relationship	Associate
Payable to equipment suppliers	$ 58,549
Siliconware Precision Industries Co., Ltd. [member]
Disclosure of transactions between related parties [Line Items]
Relationship	Entity that has significant influence over the Company
Acquisition of property, plant and equipment	$ 35,261

Capital management

12 Months Ended

Dec. 31, 2023

Disclosure of objectives, policies and processes for managing capital [abstract]

Capital management

40.

Capital management

The Group’s objectives when managing capital are to safeguard the Group’s ability to continue as a going concern in order to provide returns for shareholders and to maintain an optimal capital structure to reduce the cost of capital. In order to maintain or adjust the capital structure, the Group may adjust the amount of dividends paid to shareholders, return capital to shareholders, issue new shares or sell assets to reduce debt. The Group monitors capital on the basis of the liabilities to assets ratio. Total capital is shown as “Equity” in the consolidated statements of financial position, which is also equal to total assets minus total liabilities.

The liabilities to assets ratio at December 31, 2022 and 2023 were as follows:


	December 31, 2022	December 31, 2023
	NT$000	NT$000
Total liabilities	20,303,685	21,397,287
Total assets	44,942,945	46,160,484
Liabilities to assets ratio	45.18%	46.35%

Summary of Material Accounting Policies - Summary of Ownership Interests in Subsidiaries (Detail)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
ChipMOS U.S.A., Inc. [member]
Disclosure of joint ventures [line items]
Name of investor	The Company	The Company
Main businesses	Marketing of semiconductors and electronic related products	Marketing of semiconductors and electronic related products
Location	San Jose, USA	San Jose, USA
Percentage of Ownership (%)	100.00%	100.00%
ChipMOS TECHNOLOGIES (BVI) LTD. [member]
Disclosure of joint ventures [line items]
Name of investor	The Company	The Company
Main businesses	Holding company	Holding company
Location	British Virgin Islands	British Virgin Islands
Percentage of Ownership (%)	100.00%	100.00%
ChipMOS SEMICONDUCTORS (Shanghai) LTD. [Member]
Disclosure of joint ventures [line items]
Name of investor	ChipMOS BVI	ChipMOS BVI
Main businesses	Marketing of semiconductors and electronic related products	Marketing of semiconductors and electronic related products
Location	Shanghai, People’s Republic of China (“PRC”)	Shanghai, People’s Republic of China (“PRC”)
Percentage of Ownership (%)	100.00%	100.00%