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Summary Translation
Recently, investors have been highly concerned about the mass production progress of the Trainium 3 substrate (ABF substrate) and are worried about potential delay risks. Through supply chain research, we have outlined the core progress: by the end of 2025, two substrate suppliers will start small batch shipments, but due to updates in substrate design, mass production will need to be paused until March-April 2026; this design update is planned to complete Tape-out (wafer fabrication) in December, involving only a single-layer substrate adjustment aimed at further enhancing accelerator performance, which is expected to be successfully implemented. Starting in April 2026, monthly production capacity is expected to significantly increase compared to the small batch production phase in December, and since the beginning of this year, the Trainium 3 substrate has undergone multiple Tape-outs, establishing a solid foundation for technological iteration.
Impact on Core Targets
1. Unimicron (3037.TW, Buy)
Although substrate shipments will be paused in the first quarter of 2026, we maintain our original assumptions regarding Unimicron’s Trainium-related business in 2026, with no downside risk. From Q4 2025 to 2026, the company’s main substrate production line will remain at full capacity, driven by strong demand in the TPU (Tensor Processing Unit) sector—Unimicron’s market share in this area is expected to significantly increase in 2026. Additionally, in the current tight market environment for T-glass supply, Unimicron’s strong purchasing power (comparable only to Japan’s Ibiden (4062.JP, Buy)) further highlights its competitiveness in most AI/HPC (High-Performance Computing) projects.
2. Copper Clad Laminate (CCL) and PCB Industry
Due to the delay in the official mass production of the Trainium 3 substrate until March-April 2026, the recovery of procurement for copper clad laminates for this product is expected to be postponed until April or even later (only the small batch substrate shipments in December may drive small batch demand for copper clad laminates in early 2026). Therefore, the ‘window period’ of impact on the copper clad laminate/PCB industry due to the delay in Trainium 3 mass production will last at least 5-6 months. In the long term, we are optimistic about the prospects of the copper clad laminate/PCB industry, but in the short term, caution is needed for companies with high exposure to Trainium business, as their catalysts will be relatively limited.
Key Risk Indicators
• Technical Risk: The Trainium 3 substrate’s December design update Tape-out may not meet expectations, potentially leading to further delays in mass production.
• Demand Risk: Demand in the TPU and AI/HPC sectors may not meet expectations, affecting Unimicron’s substrate capacity utilization and market share growth pace.
• Supply Chain Risk: Tightening supply of key materials such as T-glass may exceed Unimicron’s purchasing capacity, affecting project delivery.
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