Inside every printed circuit board in AI hardware, from 800G switches to accelerator boards, sits a material the market barely talks about: glass fabric, the reinforcement in copper clad laminate (CCL). At signalling speeds of 224 Gb/s per lane, ordinary E-glass generates too much loss, so designers have to reach for low dielectric constant (low-Dk) grades, woven from filament thinner than a human hair. Every hardware generation adds board layers and pushes fabric consumption per system higher, while quality requirements get tighter.
Supply of this material is extremely concentrated. Japan's Nitto Boseki leads the top grades (NE-glass, T-glass), backed up by a narrow field of Taiwanese producers. The barrier to entry is decades of know-how in glass chemistry and in weaving ultra-thin yarns, and a new furnace takes roughly two years to build and then has to run without interruption. The investment decisions were made before the AI boom, so the market has entered a phase of structural shortage: order books run into 2027, price lists move up quarter after quarter, and customers are accepting long-term contracts and prepayments just to lock in allocations.