⚡ When the world's biggest chip foundry decides to quit a technology your products depend on, you have two choices: find another supplier, or learn to make it yourself.

ROHM, the Kyoto-based chipmaker, is betting on the harder one. When TSMC announced it would walk away from manufacturing gallium nitride (GaN) power chips, ROHM was left especially exposed, because its flagship 650-volt parts were fabricated inside TSMC's fabs. Six months after its president publicly called the news a heavy blow, engineers are now gathering at a factory in Hamamatsu for a countdown to mass production in 2027. The question hanging over them: can Japan build this tiny but critical chip on its own?

The day a CEO admitted it hurt

GaN is a next-generation material for power semiconductors, the chips that convert and manage electricity. Next to the silicon that has dominated for decades, GaN runs cooler, switches faster, and packs more performance into a smaller footprint. Those palm-sized fast chargers for your laptop? GaN. The compact power supplies keeping AI data centers from overheating? Increasingly, GaN.

ROHM moved into the field early. In March 2022 it began mass-producing 150V GaN parts at its subsidiary, ROHM Hamamatsu. But for the higher-voltage 650V devices that drive most of the demand, it leaned on TSMC, adopting the foundry's 650V GaN process in 2023 and signing a strategic automotive-GaN partnership in December 2024.

Then the ground shifted. TSMC decided to exit GaN foundry services entirely by the end of July 2027. At an earnings briefing in November 2025, ROHM president Katsumi Azuma didn't sugarcoat it, calling the decision a serious and painful blow. Lose your foundry, and your flagship product line can simply stop shipping.

Why TSMC is walking away from GaN

Why would the world's most important chipmaker abandon a growing market? The answer is arithmetic.

GaN is expanding, but next to TSMC's core business of advanced processors for AI, it's small and lower-margin. TSMC plans to repurpose the fab it used for GaN into a hub for the advanced packaging, technologies like CoWoS, that's essential to assembling AI chips for customers such as NVIDIA. Faced with limited capacity, it's funneling everything toward the most lucrative work.

The other pressure comes from China. Innoscience, the Chinese company that leads the global GaN power-device market, is one of several low-cost GaN fabs scaling up fast. In a market where foundry prices keep falling, TSMC had little reason to stay. The company itself has only said the move reflects market dynamics and its long-term strategy.

Eighteen months to mass production

If the foundry disappears, make the chips yourself. That's the road ROHM chose.

In February 2026, ROHM announced it had licensed TSMC's GaN process technology and would build an integrated, in-house production line. TSMC's know-how is being transferred to the Hamamatsu plant, where ROHM is standing up an 8-inch (200mm) wafer line with a target of having production running within 2027. According to EE Times, engineers have been converging on Hamamatsu to hit a tight goal of roughly eighteen months to volume manufacturing.

The automotive partnership with TSMC will be wound down once the transfer is complete. It isn't a falling-out but a pivot, and the two will keep collaborating on making power systems smaller and more efficient. As a hedge against a sudden demand spike, ROHM has also lined up TSMC affiliate VIS (Vanguard International Semiconductor) to take on some volume.

Moving to 8-inch wafers isn't just a like-for-like swap. Bigger wafers yield more chips per run, which feeds directly into cost competitiveness.

China leads, America follows

ROHM's engineering is well regarded. But there's a hard truth to face: no Japanese company sits in the top five of the global GaN power-device market.

By TrendForce's 2024 figures, China's Innoscience leads with 29.9%, followed by America's Navitas (16.5%), EPC (12.4%), Germany's Infineon (10.3%), and America's Power Integrations (9.8%). The upper tier belongs to China and the United States.

TSMC's withdrawal has set off a scramble. Navitas is shifting production of its 650V parts to Taiwan's Powerchip over the next year or two. GlobalFoundries has licensed 650V and 80V technology from TSMC and is accelerating a U.S.-based GaN manufacturing hub. Infineon, meanwhile, has pushed ahead with 300mm wafer technology that yields 2.3 times more chips per wafer than 200mm lines. Everyone is trying to absorb the gap TSMC leaves into their own supply chain.

Betting the factory on vertical integration

ROHM's strategy is vertical integration: owning the chain from design to fabrication. Make the chips in-house rather than outsourcing them, and you can cut costs, move faster, and differentiate your products. In effect, the company turned a crisis into the argument for bringing production home.

There's a tailwind, too. NVIDIA's 2025 push toward 800V high-voltage DC power architecture for data centers vaulted GaN into a starring role. Yole Group expects data centers and telecom alone to generate more than $380 million in GaN revenue by 2030. Adoption is also spreading to EV onboard chargers, and ROHM is working with Mazda toward commercialization in fiscal 2027.

The hard constraint is time. There's less than two years until TSMC's exit, and China and the U.S. will keep pulling ahead in the meantime. Gallium prices have climbed 123% since early 2025, making raw materials harder to secure. Even so, the choice not to leave a critical component in another country's fabs carries a value beyond cost.

Who makes a chip, and where, has become a matter of national security. Which countries does yours rely on for the components inside everything you own?

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