TrendForce Jibang Consulting: Rubin platform cable-free architecture and ASIC high HDI layer architecture drive the PCB industry to become the core of computing power

The Zhitong Finance App learned that the latest research by TrendForce Jibang Consulting indicates that AI server design is undergoing a structural transformation. From the cable-free architecture of the Nvidia (NVDA.US) Rubin platform to the high-rise HDI design of ASIC servers developed by major cloud manufacturers, PCBs are no longer just circuit carriers, but have become the core layer for releasing computing power. PCBs have officially entered the “Three High Era” of high frequency, high power consumption, and high density. The agency believes 2026 will be a new starting point for PCBs to “drive value with technical content.”

The cableless (cableless) interconnect design used in Rubin generation servers is the starting point for the reversal of the PCB industry's position. In the past, high-speed transmission between GPU and Switch relied on cables, but now they are directly handled by multi-layer PCB boards such as Switch Tray, Midplane, and CX9/CPX, making signal integrity (SI) and transmission stability the core indicators of design.

In order to achieve low loss and low latency, the Rubin platform has been fully upgraded using materials, including the Switch Tray using M8U grade (Low-Dk2+ HVLP4) and 24-layer HDI board design, and the Midplane and CX9/CPX are imported into M9 (Q-Glass+ HVLP4), with a maximum number of layers of 104 layers. This increased the PCB value of a single server by more than two times compared to the previous generation, and changed the design focus from board wiring to machine interconnection and cooling collaboration. Furthermore, Rubin's design logic has become the common language of the industry. ASIC AI servers, including Google TPU V7 and AWS Trainium3, also use high-grade HDI, low Dk materials, and extremely low roughness copper foil.

On the other hand, AI server demand for PCB performance also directly drives qualitative changes in upstream materials. Glass fiber cloth and copper foil, with dielectric and thermal stability as the core indicators, have become the key to affecting the efficiency of the whole machine.

In terms of glass fiber cloth, Japan's Nittobo (Nittobo) spent 15 billion yen to expand production of T-glass, which is out of stock. Mass production is expected to increase by 3 times the current situation by the end of 2026. T-glass has a low coefficient of thermal expansion and high modulus. It is the core material for ABF and BT carrier boards, and the price is about several times that of e-glass. The Q-glass and Low-DK2 used by CCL on the other end have extremely low dielectric constants and dielectric losses as future directions.

In terms of copper foil, as the impact of high-speed transmission and skin collection effect (Skin Effect) intensified, low-roughness HVLP4 copper foil became mainstream, but production capacity was reduced by about half for every upgrade, making supply tight for a long time, and bargaining power gradually returned from downstream machines to upstream materials.