Top 10 OSAT (Outsourced Semiconductor Assembly and Test) Companies

Ⅰ The flow of semiconductor assembly and test

The semiconductor assembly and test process flow typically begins when the wafer from the front-end fabrication process is cut into individual chips (Dies) through a scribing or dicing process. These cut dies are then mounted with adhesive onto a corresponding substrate or lead frame (frame island).

Next, the die's bond pads are connected to the corresponding leads of the substrate using ultra-fine metal wires (gold, tin, copper, aluminum) or conductive resin (flip-chip bonding). After interconnection, a series of operations are performed to seal the package, such as Molding, Post Mold Cure, Trim & Form, Plating, and Printing.

After packaging is completed, the finished product undergoes rigorous testing, usually through Incoming, Functional Test, and Packing processes, before finally being warehoused for shipment. A typical packaging process includes dicing, die attach, wire bonding (or flip-chip), molding, laser marking, trimming/forming, inspection, and final testing.

Semiconductor devices come in many package forms, generally classified into three categories: pin insertion type (Through-Hole), surface mount type (SMT), and advanced packaging. From DIP, SOP, QFP, PGA, BGA to CSP, and now SiP (System in Package) and 2.5D/3D Chiplets, technical indexes have become progressively advanced.

In general, semiconductor packaging has experienced four major innovations:    
1. The 1980s shift from pin-insertion to surface-mount, increasing PCB assembly density.    
2. The 1990s emergence of ball grid arrays (BGA), meeting demands for high pin counts.    
3. The 2000s move to Chip-Scale Packages (CSP) and System-in-Package (SiP) to minimize size.    
4. The current era of Heterogeneous Integration (Chiplets, CoWoS, FO-PLP), driven by AI and High-Performance Computing (HPC), which focuses on interconnecting multiple dies into a single high-performance package.

Ⅱ Revenue of global OSAT companies 2023-2024

OSAT stands for Outsourced Semiconductor Assembly and Test. After a period of inventory correction in 2023 due to a post-pandemic slowdown, the market rebounded in 2024, driven heavily by demand for Artificial Intelligence (AI) chips and High-Performance Computing (HPC).

According to recent industry reports (TrendForce/Yole), the top 10 OSAT companies hold a dominant market share, exceeding 80% of the global total. While consumer electronics faced headwinds in 2023, the rapid adoption of advanced packaging for AI GPUs and accelerators has become the primary growth driver for top-tier players like ASE and Amkor.

Notable Changes in Recent Rankings:

• ASE remains the undisputed industry leader, heavily investing in VIPack™ and CoWoS (Chip-on-Wafer-on-Substrate) capacity.

• JCET (China) has solidified its position in the top 3, showing strong resilience and growth in the automotive and advanced packaging sectors.

• Tongfu Microelectronics (TFME) has risen rapidly, benefiting significantly from its close partnership with AMD, especially in packaging CPUs and GPUs for data centers.

• UTAC was acquired by Wise Road Capital and is often now consolidated into rankings under the Wise Road entity or related holding groups, though it remains a key player in automotive and analog testing.

Top 10 Global OSAT Companies Revenue Estimates (2023-2024 Period)
(Approximate values in USD Billions)

Note: Revenue figures are approximate conversions from local currencies based on 2023/2024 fiscal reports. "Wise Road" includes revenue from acquired entities like UTAC.

The concentration of the top players continues to increase. The "Big 3" Chinese OSATs (JCET, TFME, Huatian) have seen significant market share gains due to localization trends and heavy investment in advanced packaging technologies like Chiplets and 2.5D integration.

Ⅲ An overview of the top 10 OSAT companies

1. ASE (ASE Technology Holding)

Headquartered in Kaohsiung, Taiwan, ASE was founded in 1984. It is the world's largest provider of outsourced semiconductor assembly and test services. In 2018, ASE officially merged with SPIL (Siliconware Precision Industries), forming ASE Technology Holding, further cementing its leadership.

ASE is a pioneer in System-in-Package (SiP) and advanced packaging. Their VIPack™ platform supports vertical integration for AI, 5G, and HPC applications. They are a critical partner to TSMC for CoWoS backend processing.

2. Amkor

Amkor Technology, founded in 1968 and headquartered in Tempe, Arizona, USA, is the world's second-largest OSAT. Amkor is a strategic partner for major automotive and communications chipmakers.

Recent major moves include the expansion of their manufacturing footprint in Vietnam and a new advanced packaging facility in Peoria, Arizona, to support US domestic semiconductor manufacturing (the CHIPS Act). Amkor specializes in Flip Chip, Wafer-Level Packaging, and through-silicon via (TSV) technology.

3. JCET

JCET (Jiangsu Changjiang Electronics Technology) is the largest OSAT in mainland China and globally ranked 3rd. Established in 1972, JCET accelerated its global reach by acquiring Singapore's STATS ChipPAC in 2015.

JCET has launched its XDFOI™ high-density multi-dimensional heterogenous integration chiplet technology, aimed at solving the power and performance bottlenecks in the post-Moore's Law era. They have production bases in China, Singapore, and Korea.

4. TFME (Tongfu Microelectronics)

TFME (formerly known as Tongfu or TFMC) was founded in 1997. It has grown rapidly through a deep strategic partnership with AMD. After acquiring AMD's assembly and test facilities in Suzhou and Penang in 2016, TFME became a primary supplier for AMD's CPUs and GPUs.

TFME currently possesses advanced capabilities in Chiplet packaging, which is essential for modern data center processors. Their "Joint Venture + Cooperation" model has allowed them to master 7nm, 5nm, and 4nm backend technologies.

5. PTI (Powertech Technology Inc.)

Founded in 1997 in Taiwan, PTI was historically known as the world's leader in Memory packaging (DRAM/NAND). However, in recent years, PTI has aggressively pivoted toward Logic IC packaging to diversify its revenue.

PTI utilizes specialized technologies like TSV and Fan-Out Panel Level Packaging (FOPLP) to serve the automotive and IoT markets.

6. Huatian Technology

Based in Tianshui, Gansu, Huatian Technology is one of the pillars of China's semiconductor backend industry. Founded in 2003, it expanded globally by acquiring FCI (FlipChip International) in the US.

Huatian provides a broad range of services from traditional lead-frame packaging to Fan-Out and TSV. They have seen significant growth by servicing the booming domestic Chinese demand for mobile and industrial chips.

7. Wise Road / UTAC

UTAC (United Test and Assembly Center), headquartered in Singapore, focuses heavily on automotive, industrial, and analog mixed-signal products. In 2020, UTAC was acquired by Wise Road Capital.

Under Wise Road, UTAC has been integrated into a larger ecosystem of semiconductor assets. They maintain a strong reputation for high-reliability packaging for automotive sensors and power management ICs (PMICs).

8. KYEC (King Yuan Electronics Corp)

Established in 1987 in Hsinchu, Taiwan, KYEC is the world's largest independent provider of semiconductor testing services (Pure-play Test). Unlike other OSATs that focus heavily on assembly, KYEC's primary revenue comes from wafer probing and final testing.

KYEC has become crucial in the AI era, as modern GPUs require significantly longer and more complex burn-in testing, driving demand for KYEC's specialized test capacity.

9. ChipMOS

ChipMOS, established in 1997, is a leader in packaging Display Driver ICs (DDIC) and Memory products. They hold a significant market share in the COF (Chip on Film) and COG (Chip on Glass) packaging used in LCD and OLED screens.

They serve major display panel manufacturers and memory makers, maintaining facilities across Taiwan and Shanghai.

10. Chipbond

Founded in 1997 in Hsinchu, Taiwan, Chipbond is ChipMOS's primary competitor. They specialize in driver IC packaging and testing, as well as bumping services (Gold bump, Solder bump).

Chipbond is integral to the supply chain for smartphones and televisions, providing the interconnect technology that links the display driver chip to the glass panel.