A predicted shortage of high-performance ABF substrates is sending ripples through the AI hardware supply chain.
This isn't just a minor supply hiccup; it's a structural bottleneck re-emerging due to a perfect storm of factors. At the heart of the issue are three interconnected drivers that have gained momentum in recent weeks.
First and foremost is a critical raw material shortage. A special type of glass fabric, known as T-Glass, is essential for making the high-layer-count substrates needed for AI chips. This material is almost entirely supplied by a single Japanese company, Nittobo. Recent reports indicate that Nittobo is struggling to meet demand, with prices already jumping 25-30% and significant new capacity not expected until late 2026. This directly squeezes the production pipeline for ABF substrates.
Second, demand is being supercharged by NVIDIA's next-generation Rubin platform. NVIDIA has confirmed that its Rubin GPUs will be deployed by major cloud providers in the second half of 2026. These new chips are more complex, requiring larger and more sophisticated ABF substrates. To avoid production delays, chipmakers and their partners are being forced to stockpile these high-end substrates well in advance, pulling demand forward into the first half of the year and amplifying the sense of urgency.
Third, the ongoing expansion of advanced packaging capacity, specifically TSMC's CoWoS technology, is solidifying this demand. As TSMC ramps up its CoWoS output to meet the insatiable demand from AI giants, it creates a rigid, non-negotiable need for a corresponding volume of high-quality ABF substrates. With major customers like NVIDIA locking in most of this capacity, the demand for substrates becomes a hard requirement rather than a flexible forecast.
This dynamic has put a spotlight on key Taiwanese substrate suppliers. Unimicron, the technology leader, is well-positioned to handle the most complex designs but trades at a premium. Kinsus, with a lower valuation, offers more potential upside as prices rise. Meanwhile, Zhen Ding-KY is emerging as a compelling "dark horse," diversifying with both high-end substrates and other AI-related circuit boards, offering a hedge against valuation risks.
- ABF Substrate: Ajinomoto Build-up Film substrate, a critical component that connects a powerful semiconductor chip to a circuit board, essential for high-performance computing.
- T-Glass: A specialized, low-dielectric glass fabric used as a raw material for high-frequency circuit boards and substrates, crucial for maintaining signal integrity in AI chips.
- CoWoS: Chip-on-Wafer-on-Substrate, TSMC's advanced packaging technology that stacks multiple chips together to create powerful, integrated processors for AI and HPC.