Amkor Technology (AMKR)
The leading US-based OSAT and a key TSMC CoWoS outsourcing partner for NVIDIA's Rubin AI chips. Amkor is the strategic overflow valve for TSMC's fully-booked advanced packaging lines — and the primary US-based advanced packaging capacity for AI chips.
1. Core Product / Service
Amkor Technology (NASDAQ: AMKR) is the world's largest outsourced semiconductor assembly and test (OSAT) company by revenue, and the only major OSAT with significant US-based advanced packaging capacity. Key AI-relevant services:
CoWoS and CoWoS-like packaging — Amkor handles NVIDIA's next-generation "Rubin" chip packaging (outsourced from TSMC due to TSMC CoWoS capacity being fully booked). Also handles AMD's CoWoS-L for Venice CPU (80,000 wafers in 2026) and automotive chips.
HBM packaging — Amkor stacks HBM for AI accelerators; the physical handling and bonding of sk-hynix HBM onto GPU base dies.
Advanced test — burn-in and testing of AI chips.
Fan-out packaging — for inference chips and custom ASICs.
Amkor is strategically positioned as the neutral OSAT that TSMC outsources to when its own CoWoS capacity is insufficient — and as a way to prevent orders flowing to Samsung [2].
2. Target Users & Pain Points
- NVIDIA — TSMC outsources some Rubin AI accelerator packaging to Amkor because TSMC's own CoWoS capacity is fully booked [2]. This is a massive vote of confidence in Amkor's technical capabilities.
- AMD — 80,000 CoWoS-L wafers in 2026 for Venice CPU (out of TSMC) [1]
- TSMC itself — uses Amkor as capacity overflow; a customer and partner simultaneously
- Broadcom — some advanced packaging for custom ASICs
- Qualcomm, MediaTek — for mobile and inference chips
Pain solved: AI chip packaging demand is unlimited (CoWoS capacity booked through 2027 at TSMC [5]) but CoWoS supply is finite. Amkor provides the overflow capacity that allows AI chip production to continue even when TSMC is fully utilized. Without Amkor, AI chip supply would be even more constrained.
3. Competitive Landscape
| Company | Position | vs Amkor |
|---|---|---|
| ASE/SPIL (ASE Technology) | #1 global OSAT; Taiwanese headquarters | ASE is larger; Amkor's advantage is US-based capacity which is strategically valued by US customers and for US-based AI chips |
| JCET / PTI (China) | Large OSAT in China | Subject to US-China tech restriction risk; less advanced packaging for leading-edge AI chips |
| SPIL | Part of ASE group | Same as above |
| Samsung Semiconductor | Internal OSAT + foundry | Samsung packages its own chips; doesn't use Amkor |
Amkor's moat: US-based advanced packaging capacity — with TSMC's US fabs still limited, Amkor's US facilities provide domestic packaging for AI chips manufactured at TSMC's US facilities or destined for US-based AI clusters. This is a geopolitical asset as well as a technical one.
4. Unique Observations
- NVIDIA CoWoS capacity: 60% of 1M global CoWoS wafers in 2026 booked by NVIDIA [3]. But TSMC's CoWoS is fully booked → outsourcing to Amkor for Rubin.
- TSMC's strategic reason for outsourcing to Amkor: prevent orders flowing to Samsung. TSMC outsources to neutral OSATs (Amkor, ASE) rather than Samsung to keep advanced packaging within its ecosystem control [2].
- CoWoS volume for Amkor: NVIDIA Vera CPU + automotive chips: ~65k wafers in 2026 outsourced outside TSMC; this includes Amkor [4]. This is growing to 140k in 2027.
- ASE and Amkor split TSMC CoWoS overflow: ASE handles most AMD CoWoS-L (80k wafers 2026); Amkor handles NVIDIA Vera CPU + automotive [1].
- HBM4 implication: Amkor's HBM stacking capacity for sk-hynix HBM + nvidia/AMD GPUs expands with HBM4 (16-Hi). The more complex stacking requires more OSAT handling.
- The critical number to track: Amkor's advanced packaging revenue as % of total. In 2025 it was rising sharply. If Amkor reports AI packaging revenue >40% of total, the supply constraint thesis is confirmed.
- Geographic advantage: Unlike Asia-based OSATs (ASE, JCET), Amkor's US presence makes it a safer partner for US hyperscalers concerned about supply chain geography.
5. Financials / Funding
- Listed: NASDAQ: AMKR; market cap ~$8B+ (2026)
- Revenue: ~$7B range (2025 est); OSAT revenue driven by AI packaging in 2025-2026
- AI packaging revenue growth: accelerated sharply in 2025-2026 as NVIDIA/AMD CoWoS outsourcing volumes increased
- Operating margin: recovering from 2023-2024 trough; AI packaging commands premium margins
6. People & Relationships
- Key customer/partner: tsmc (outsourcing partner — uniquely both customer and competitor)
- NVIDIA: packaging Rubin AI accelerator
- AMD: CoWoS-L for Venice CPU via TSMC → Amkor
- Broadcom: advanced packaging for custom ASICs
- Strategic context: Amkor is the barometer for TSMC CoWoS capacity tightness — when TSMC outsources more to Amkor, it means TSMC's own CoWoS lines are at capacity. The volume of TSMC-outsourced CoWoS at Amkor is a direct proxy for how supply-constrained advanced packaging is.