Buyers who prepaid Ibiden are now financing its rival, on Ajinomoto's film

On 28 September 2026, Samsung Electro-Mechanics won board approval for 6.78 trillion won, about $4.99 billion, of new AI substrate capacity at Sejong and in Vietnam, the largest single-product investment in its history ¹². The decisive sentence sits inside the filing↗: global big-tech customers will fund part of the new facilities and guarantee mid- to long-term volumes ¹. Two days earlier, Japanese reporting carried Nvidia's Jensen Huang saying he had "no choice but to rely on" Ibiden, with an advance payment reported at 280 billion yen to hold substrate supply ³.

Nothing produces until September 2028

The Sejong tranche alone, 4.27 trillion won, equals 43.6% of consolidated shareholders' equity; equipment spending runs through May 2028 and mass production starts that September ⁴. The market is already paying for the shortage: first-half packaging sales rose 41% and operating profit more than tripled ⁵, and brokerage consensus for the third quarter↗ stands at 605.1 billion won, 2.3 times a year earlier ⁴.

Every new line runs on one company's film

Each copper layer in these substrates is insulated by Ajinomoto Build-up Film, more than 95% of it from Ajinomoto itself, with Sekisui holding roughly the remainder ⁶. Ajinomoto has raised film prices about 30%, effective this quarter ⁷, worth 3 to 6% on finished substrates ⁶, on top of SEMCO's own 30% substrate increase in August ².

Three countries race, one landlord collects

Ibiden is spending about 500 billion yen through fiscal 2028 to lift its production load to roughly 2.5 times the 2024 level, and has doubled its own operating-profit forecast to 127 billion yen↗ ⁸. Unimicron lifted 2026 capex from NT$34 billion to NT$53.7 billion, most of the increase for ABF substrates ². SEMCO's lines ran at 89% utilization with prices up 18.7%, and it already counts Nvidia, Google and Amazon as substrate customers ⁵.

The glut case, and why the film shrugs

If AI demand slows, output that starts in September 2028 lands in a buyer's market, and each new customer takes 12 to 24 months to qualify ². Ajinomoto's counter, about 25 billion yen for 50% more capacity by 2030, leaves the decade's gap standing ⁶. Its shares are up 56% this year ⁶.

Watch the film price land

Next readings: the film hike flowing into fourth-quarter substrate costs ², the names of the customers co-funding SEMCO's plants, and a third quarter expected to set a record ⁹. You can prepay your way out of a queue. You cannot prepay your way out of the only film in town.