One Layer Above the Die — The Week Power, Passives and Materials Became the AI Rack's New Battleground

Not the Die — One Layer Above It

For four months the question was simple: who supplies the HBM, and who packages it. This week's print, simultaneously across all four chip countries, said something different. The AI rack's next bottleneck is not the wafer but one layer above the wafer — silicon capacitors under the substrate, SiC switches in the PSU, optocouplers on the gate drivers, Low-DK glass fibers in the laminate, rare-earth magnets in the power-conversion stage, tungsten in the interconnect via. Korea opened a frontal attack on Japan's Murata. Taiwan filled Delta and Lite-On's AI PSU sockets. Japan reshored the materials. The US wrote the check. The same NVIDIA 1MW rack pulled all four.

Korea — First Frontal Crack in Murata's Wall

On June 13, Samsung Electro-Mechanics (009150) disclosed a ₩1.5T silicon capacitor supply contract with a global big-tech customer. It is Korea's first frontal entry into a market controlled for a decade by Japan's Murata and TSMC's silicon-capacitor line in Taiwan. Silicon capacitors sit directly under the AI accelerator package on the substrate; they absorb the transient current a Blackwell or Rubin draws when 1.4kW of compute fires up. The ₩1.5T number — call it ~$1.1B over multi-year — is large enough that the buyer can only be Microsoft, Meta, Google or Amazon, and large enough to imply that Korea is being deliberately designed in as a second source the customer wants to keep healthy. It is the same playbook that built SK Hynix's HBM moat — buyer funds a second supplier ring to discipline the incumbent. Now Korea has crossed into Japan's most defended subcomponent.

Taiwan — Side Doors Through Power, Optics and Glass

The Taiwan version of the same trade printed the same week. Everlight (2393) confirmed at its AGM that both its optocouplers and its SiC line are designed into Delta Electronics' and Lite-On's AI server PSUs — the 5.5kW shelves NVIDIA's HGX racks now require, where gate-driver isolation and high-voltage switching live. Episil (3016) told investors that silicon-photonics epitaxy will reach ~5% of 2026 revenue and double in 2027, while SiC and GaN have landed "Tier-1" customer slots. Taiwan Glass (1802) committed an additional NT$2B (~$65M) to Low-DK glass-fiber capacity for AI substrate laminates. None of these is the die. All are mandatory. All are getting pricing power back for the first time since 2022.

Japan — Material Lock-Down, and the Tungsten Shadow