Japan power semiconductor deal stalls as Rohm, Toshiba, Mitsubishi haggle

Japan's failed power-semiconductor consolidation is not a negotiation hiccup — it is a structural collision between three divergent technology roadmaps and a demand shock that outpaced their strategic planning. Rohm's SiC discrete devices, Toshiba's IGBT modules, and Mitsubishi's traction inverters each anchor different value pools; the real fight is over who owns the integration layer. The technical fallout is already compounding: duplicated SiC substrate capex while Infineon and STMicro lock in AI data-center power design wins. Chinese SiC players are scaling capacity at roughly 3× the Japanese pace, and within 12 months Japan's automotive-grade SiC share risks sliding below 15%. On the compliance front, METI's SEALION subsidies carry domestic-capacity covenants. A stalled merger dilutes subsidy efficiency and weakens Tokyo's supply-chain-security narrative at a moment when export-control regimes are tightening. Outlook: within 18 months, expect a government-brokered, foreign-capital-injected hybrid — a Rapidus 2.0. If that also fails, Japanese power semiconductors will permanently retreat into niche segments, ceding the main battlefield to Europe and mainland China.