ASE Technology Holding (ASEH) is a Taiwan-based holding company that owns the semiconductor assembly and test businesses of ASE and SPIL and the electronics manufacturing services business of USI. Its two main pillars are outsourced semiconductor assembly and test and EMS, while advanced packaging for chiplets, HBM and 2.5D/3D integration is an increasingly important growth driver.
This article explains the difference between ASE and ASEH, the group’s businesses, AI-era packaging technologies, global locations, 2025 financial performance and competitors based on information available in 2026.
ASE Technology Holding in brief
- One of the world’s largest semiconductor back-end manufacturing groups
- Combines the OSAT operations of ASE and SPIL with USI’s EMS operations
- Developing FOCoS, 2.5D/3D, SiP and chiplet/HBM integration
- 2025 revenue of NT$645.388 billion and net income attributable to owners of NT$40.016 billion
- What is ASE Technology Holding?
- ASE vs. ASE Technology Holding
- Two businesses: semiconductor back-end services and EMS
- Advanced packaging for AI: FOCoS, chiplets and HBM
- Customers and end markets
- Global manufacturing locations
- History and major transactions
- Financial performance
- Competitors
- Frequently asked questions
- Stock
- Summary
What is ASE Technology Holding?
ASE Technology Holding Co., Ltd. was established in 2018 as a listed holding company in Taiwan. Its shares trade under code 3711 on the Taiwan Stock Exchange, while its American depositary receipts trade under ASX on the New York Stock Exchange.
| Company | ASE Technology Holding Co., Ltd. |
|---|---|
| Chinese name | 日月光投資控股股份有限公司 |
| Abbreviation | ASEH |
| Established | 2018 |
| Headquarters | Kaohsiung, Taiwan |
| Chairman and CEO | Jason C.S. Chang |
| Employees | 105,955 at the end of 2025 |
| Markets | Taiwan Stock Exchange and New York Stock Exchange |
| Tickers | TWSE: 3711; NYSE: ASX (ADR) |
| Main businesses | Semiconductor assembly and test, advanced packaging and EMS |
Headquarters map
ASE Group is headquartered in Kaohsiung, the center of a major semiconductor manufacturing cluster in southern Taiwan.
ASE vs. ASE Technology Holding
The names are often used interchangeably, but they refer to different legal entities. Advanced Semiconductor Engineering, Inc. is an operating company responsible for semiconductor packaging and testing. ASE Technology Holding is the listed parent company formed in 2018 to own ASE and Siliconware Precision Industries, commonly known as SPIL, together with other group operations.
| Name | Role |
|---|---|
| ASE Technology Holding | Listed parent company of the group |
| ASE | Semiconductor assembly, packaging and testing |
| SPIL | Semiconductor packaging and testing subsidiary |
| USI | Electronics manufacturing services and system/module assembly |
Two businesses: semiconductor back-end services and EMS
Assembly, test and material operations
ASE and SPIL package and test semiconductor dies after wafer fabrication. Services include wire-bond and flip-chip packages, wafer-level packaging, fan-out packaging, system-in-package, substrate and material technologies, and final testing.
Electronics manufacturing services
USI provides design, miniaturization, module production and final system assembly. This gives ASEH a broader scope than a pure OSAT provider, extending from semiconductor packaging to electronics modules and systems.
2025 revenue mix
| Business | Approximate share of 2025 revenue |
|---|---|
| Packaging | 48% |
| Testing | 11% |
| EMS | 40% |
| Other | 1% |
Packaging revenue reached NT$308.343 billion and test revenue reached NT$71.900 billion in 2025, while EMS revenue declined to NT$257.193 billion. Semiconductor assembly and test, including demand related to AI and high-performance computing, drove consolidated growth.
Advanced packaging for AI: FOCoS, chiplets and HBM
AI accelerators combine large compute dies, high-bandwidth memory and multiple chiplets. Advanced packaging affects interconnect density, data bandwidth, power consumption and thermal performance, making it a critical part of AI-system design.
- FOCoS: ASE’s fan-out chip-on-substrate platform
- 2.5D and 3D integration: dense connections among logic, memory and chiplets
- FCBGA: substrates and packages for large high-performance chips
- SiP: integrating multiple functions into one package or module
- HBM integration: connecting stacked memory close to AI and HPC processors
FOCoS is an ASE platform, whereas CoWoS is a TSMC platform. Both address high-performance multi-die integration, but their structures, process responsibilities and supplier ecosystems differ.
Customers and end markets
ASEH serves integrated device manufacturers, fabless chip companies and electronics brands across computing, communications, automotive, industrial and consumer markets. The company does not publicly identify every customer, so lists based only on media reports should not be treated as complete or current.
Global manufacturing locations
| Region | Main operations | Role |
|---|---|---|
| Taiwan | Kaohsiung, Chungli and SPIL sites | Core advanced packaging, high-volume assembly and testing |
| Malaysia | Penang operations, including expanded capacity | Automotive, memory, power and sensor back-end services |
| Japan | Takahata, Yamagata | ASE Japan packaging operations |
| Korea and the Philippines | Former Infineon-related back-end sites | Power-semiconductor and sensor capability |
| United States | ISE Labs and related operations | Semiconductor testing, engineering and customer support |
ASE opened its fifth Malaysian plant in February 2025 and integrated the former Analog Devices Penang facility into the group in May 2026. See the official ASE Malaysia page.
History and major transactions
- 1984: Advanced Semiconductor Engineering was founded
- 2010: the group expanded its EMS business through its investment in USI
- 2016: ASE and SPIL agreed to form a joint holding company
- 2018: ASE Technology Holding was established and ASE and SPIL became wholly owned subsidiaries
- 2024: the group acquired former Infineon back-end operations in Korea and the Philippines
- 2026: the former Analog Devices Penang facility was integrated into ASE Group
Financial performance
| Year | Revenue | Net income attributable to owners | Gross margin | Operating margin |
|---|---|---|---|---|
| 2023 | NT$581.914bn | NT$31.725bn | 15.8% | 6.9% |
| 2024 | NT$595.410bn | NT$32.483bn | 16.3% | 6.6% |
| 2025 | NT$645.388bn | NT$40.016bn | 17.7% | 8.0% |
Revenue increased 8.4% in 2025 and net income attributable to owners rose by approximately 25%. The main questions for future performance are the scale and utilization of AI-oriented advanced-packaging capacity, returns on investment in Kaohsiung and Malaysia, and the different margin profiles of the OSAT and EMS businesses. Source: ASEH 2025 full-year results.
Competitors
| Company | Positioning | Difference from ASEH |
|---|---|---|
| ASEH | ASE and SPIL OSAT operations plus USI EMS | Broad scope from semiconductor back-end services to system assembly |
| Amkor | Large US-headquartered OSAT provider | Global advanced, automotive and communications packaging |
| JCET | Major China-based OSAT provider | Strong China-market position and expanding advanced packaging |
| PTI | Taiwan memory OSAT specialist | Greater focus on DRAM, NAND and HBM-related services |
| KYEC | Taiwan semiconductor test provider | More concentrated in outsourced testing |
Frequently asked questions
What does ASE do?
ASE packages and tests semiconductor dies. The listed parent, ASE Technology Holding, also owns SPIL and USI’s electronics manufacturing services operations.
Does ASE fabricate semiconductor wafers?
Its main role is not front-end wafer fabrication. ASE specializes in assembly, packaging and testing after wafer fabrication, while USI produces electronic modules and systems.
What is the difference between FOCoS and CoWoS?
FOCoS is ASE’s fan-out chip-on-substrate technology, while CoWoS is TSMC’s advanced-packaging platform. Both serve AI and HPC integration but use different process flows and supplier responsibilities.
Stock
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Summary
ASE Technology Holding combines the semiconductor assembly and test operations of ASE and SPIL with USI’s EMS business, making it one of the world’s largest semiconductor manufacturing-services groups. In the AI era, FOCoS, 2.5D/3D, FCBGA and chiplet/HBM integration are becoming increasingly important. Investors should separate the economics of advanced OSAT operations from EMS and monitor capacity utilization, margins and returns on new facilities.
