According to the latest research from TrendForce, AI server design is undergoing a structural transformation. From Nvidia's (NVDA.US) Rubin platform's cableless architecture to high-layer HDI designs in cloud giants' self-developed ASIC servers, PCBs are no longer just circuit carriers but have become the core layer for unleashing computing power. The PCB industry has officially entered the "three-high era" of high frequency, high power, and high density. The agency believes 2026 will mark a new starting point where PCB value is driven by technological sophistication.

The cableless interconnect design adopted by Rubin-generation servers signifies a turning point for the PCB industry. Previously, high-speed transmission between GPUs and switches relied on cables, but now multilayer PCBs such as Switch Tray, Midplane, and CX9/CPX directly handle these connections, making signal integrity (SI) and transmission stability core design metrics. To achieve low loss and low latency, the Rubin platform has upgraded materials comprehensively—Switch Tray uses M8U-grade (Low-Dk2 + HVLP4) with a 24-layer HDI design, while Midplane and CX9/CPX incorporate M9 (Q-glass + HVLP4), with layers reaching up to 104. This increases the PCB value per server by over two times compared to the previous generation and shifts design focus from board wiring to system-level interconnect and thermal management.

Moreover, Rubin’s design logic has become an industry standard, with ASIC AI servers like Google’s TPU V7 and AWS Trainium3 also adopting high-layer HDI, low-Dk materials, and ultra-low roughness copper foil. Meanwhile, the performance demands of AI servers on PCBs are driving qualitative changes in upstream materials. Glass fiber cloth and copper foil, with dielectric and thermal stability as key metrics, are now critical to overall system efficiency.

In glass fiber cloth, Japan’s Nittobo is investing ¥15 billion to expand production of T-glass, which is in short supply, with mass production expected by late 2026—tripling current capacity. T-glass, featuring low thermal expansion and high modulus, is a core material for ABF and BT substrates, priced several times higher than E-glass. Meanwhile, Q-glass and Low-DK2, used in CCL, are emerging as future standards due to their ultra-low dielectric constants and loss.

For copper foil, as high-speed transmission and skin effect intensify, low-roughness HVLP4 copper foil has become mainstream. However, each upgrade reduces capacity by about half, leading to long-term supply constraints and shifting pricing power from downstream manufacturers back to upstream material suppliers.