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Segment Information - Financial Segment Information for Operating Segments (Detail) $ in Thousands, $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2024 TWD ($) | Dec. 31, 2024 USD ($) | Dec. 31, 2023 TWD ($) | Dec. 31, 2022 TWD ($)
Revenue |  |  |  |
Revenue | $ 22,695,909 | $ 692,159 | $ 21,356,228 | $ 23,517,064
Operating profit (loss) | 1,273,937 | 38,851 | 1,908,452 | 3,216,679
Depreciation expenses | (4,856,186) |  | (4,779,333) | (4,751,902)
Share of profit of associates | 2,683 | 82 | 219,891 | 453,715
Interest income | 197,719 | $ 6,030 | 193,189 | 57,199
Interest expense | (278,581) |  | (265,957) | (142,439)
Purchase of property, plant and equipment | 5,451,431 |  | 3,228,471 | 4,918,482
External [member] |  |  |  |
Revenue |  |  |  |
Revenue | 22,695,909 |  | 21,356,228 | 23,517,064
Operating segments [member] | Testing [member] |  |  |  |
Revenue |  |  |  |
Revenue | 4,967,849 |  | 4,394,726 | 5,243,997
Operating profit (loss) | 625,435 |  | 514,707 | 1,253,477
Depreciation expenses | (1,075,612) |  | (1,065,689) | (1,042,455)
Purchase of property, plant and equipment | 1,555,415 |  | 749,158 | 1,086,682
Operating segments [member] | Testing [member] | External [member] |  |  |  |
Revenue |  |  |  |
Revenue | 4,967,849 |  | 4,394,726 | 5,243,997
Operating segments [member] | Assembly [member] |  |  |  |
Revenue |  |  |  |
Revenue | 5,390,447 |  | 4,629,430 | 6,705,898
Operating profit (loss) | (1,190,575) |  | (1,180,481) | (93,585)
Depreciation expenses | (799,273) |  | (722,462) | (694,835)
Purchase of property, plant and equipment | 1,273,837 |  | 568,289 | 957,790
Operating segments [member] | Assembly [member] | External [member] |  |  |  |
Revenue |  |  |  |
Revenue | 5,390,447 |  | 4,629,430 | 6,705,898
Operating segments [member] | LCDD [member] |  |  |  |
Revenue |  |  |  |
Revenue | 7,318,997 |  | 7,821,640 | 7,288,642
Operating profit (loss) | 1,281,862 |  | 2,058,285 | 1,795,741
Depreciation expenses | (2,568,610) |  | (2,547,253) | (2,505,297)
Purchase of property, plant and equipment | 2,257,968 |  | 1,756,590 | 2,677,489
Operating segments [member] | LCDD [member] | External [member] |  |  |  |
Revenue |  |  |  |
Revenue | 7,318,997 |  | 7,821,640 | 7,288,642
Operating segments [member] | Bumping [member] |  |  |  |
Revenue |  |  |  |
Revenue | 5,018,616 |  | 4,510,432 | 4,278,527
Operating profit (loss) | 555,419 |  | 522,386 | 268,159
Depreciation expenses | (405,330) |  | (435,709) | (500,863)
Purchase of property, plant and equipment | 364,139 |  | 152,908 | 196,521
Operating segments [member] | Bumping [member] | External [member] |  |  |  |
Revenue |  |  |  |
Revenue | 5,018,616 |  | 4,510,432 | 4,278,527
Operating segments [member] | Others [member] |  |  |  |
Revenue |  |  |  |
Revenue | 60,131 |  | 59,481 | 50,600
Operating profit (loss) | 1,863 |  | (6,194) | (6,821)
Depreciation expenses | (7,361) |  | (8,220) | (8,452)
Share of profit of associates | 119,118 |  | 420,393 | 884,555
Interest income | 197,719 |  | 193,189 | 57,199
Interest expense | (278,581) |  | (265,957) | (142,439)
Purchase of property, plant and equipment | 72 |  | 1,526 | 0
Operating segments [member] | Others [member] | Intersegment [member] |  |  |  |
Revenue |  |  |  |
Revenue | 60,131 |  | 59,481 | 50,600
Elimination [member] |  |  |  |
Revenue |  |  |  |
Revenue | (60,131) |  | (59,481) | (50,600)
Operating profit (loss) | (67) |  | (251) | (292)
Share of profit of associates | (116,435) |  | (200,502) | (430,840)
Elimination [member] | Intersegment [member] |  |  |  |
Revenue |  |  |  |
Revenue | $ (60,131) |  | $ (59,481) | $ (50,600)

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