The layer nobody sees

Before a graphics processor can be packaged, the silicon has to be mounted on something. That something is a build-up substrate: a laminated carrier of resin film and copper that routes tens of thousands of connections out of the chip stack and into the board. AI packages are getting physically larger and adding memory stacks, which means more layers, bigger panels and lower yields — and the industry that supplies them has spent a decade being treated as a commodity laminate business.

It is not being treated that way now. Ibiden, the Japanese group founded in 1912 that makes package substrates in its Electronics division alongside a ceramics business supplying diesel particulate filters, grew revenue 26.4% in the June quarter to ¥123.2bn — its fourth consecutive acceleration. Operating margin reached 21.1%, from 18.1% a year earlier. On 4 August it lifted its net profit forecast for the year to March 2027 to ¥84bn from ¥58bn, ahead of the ¥73.3bn analysts expected.

The Taiwanese carrier makers moved further. Unimicron, the Taoyuan maker of printed circuit boards and flip-chip carriers, expanded gross margin by 11.6 points in four quarters to 24.7%, with operating income up 342%. Nan Ya PCB, the Nan Ya Plastics subsidiary that builds substrates for processors, graphics chips and memory modules, expanded gross margin by 15.2 points and swung from a small quarterly loss to NT$2.90bn of operating income. Kinsus, a smaller Taoyuan carrier specialist, grew revenue 30.7% with margin up five points.

Why the pricing is holding

The mechanism is unusually legible. Demand for flip-chip ball-grid-array (FCBGA) substrates exceeds available capacity by more than 50%. Ajinomoto, the Japanese food group that controls roughly 98% of the intellectual property behind the build-up film these carriers are made from, raised film prices 30% for the third quarter, and substrate prices themselves are up 5-10% for the second half. TrendForce models the market moving from rough balance this year to a 22% shortfall in 2027 and 29% in 2028, despite $19.1bn of announced expansion.

Everyone is spending into it. Ibiden's board approved about ¥500bn of electronics capital spending through March 2029, targeting 2.5x its current substrate capacity, with its Ono plant — which started AI server output in October 2025 — still using only half its building. Unimicron raised 2026 capex a third time, to NT$53.7bn, with 80-85% aimed at build-up substrate. Ibiden and Unimicron between them hold about 74% of the FCBGA market, but Ibiden's grip on the very highest end is loosening as Unimicron qualifies. One caution on pricing: Ibiden itself told analysts last October it was not optimistic about product prices, even while describing its high-end capacity as sold out.

What the shares already assume

Gross margins here range from 10% at LG Innotek to 36% at Ibiden, so price against gross profit is the comparable lens. On that basis Ibiden has gone from 7.9x trailing gross profit a year ago to 17.8x in February to 40.0x now. Unimicron went from 12.7x to 65.3x, Kinsus from 6.2x to 45.0x, and Nan Ya PCB stands at 100.8x — dearest in the group on every measure.

The prior cycle is the uncomfortable comparison. Unimicron's trailing gross profit of NT$27.3bn is 54% of the NT$50.4bn it earned in 2022, when the last substrate shortage pushed its gross margin to 35.9%. Nan Ya PCB's is 29% of its 2022 figure; Kinsus remains 37% below. Only Ibiden has cleared the old peak, at ¥137.7bn against ¥127.5bn. Consensus closes the gap by assuming acceleration from here: Unimicron revenue up 48.7% in 2027 and Nan Ya PCB up 61.4%, faster than either is currently reporting. Nan Ya PCB's 76x forward earnings only becomes 29x if that lands, and analyst targets for it span NT$875 to NT$2,444.

The one going the other way

AT&S, the Austrian board and substrate maker in Leoben and the smallest of the group at €6.1bn, has fallen 34% from its June high. In that stretch it swung from a €55.9m quarterly loss to €40.9m of profit, gross margin rising from 5.5% to 22.2%, and raised full-year revenue growth guidance to 45-55% with margin guidance lifted and Malaysian expansion covered by long-term commitments from AMD and one other customer. It trades at 14.7x forward gross profit.

The two Korean names show the re-rating is specific. Samsung Electro-Mechanics earns only about 22% of revenue from substrates, the rest from ceramic capacitors and optics, yet carries Ibiden-like multiples. LG Innotek, mostly camera modules, sits at 5.5x forward gross profit. Strip both out and the remaining five average a 636% twelve-month gain, against 614% for all seven.

Recent trading has been driven by index moves as much as by substrates. Six of the seven had their best session on 31 July, when the KOSPI rose 17.9%, its largest one-day gain on record. Remove each company's two best days from the past month and the group's 10.9% average gain becomes a 14.8% decline. Unimicron and Kinsus made fresh highs on 17-18 August; Ibiden is 25% below its June peak.

The setup

Where it stands — Substrate profits are inflecting hard, but multiples have expanded roughly five to seven times over twelve months against far smaller gross-profit growth. Would confirm — Unimicron and Nan Ya PCB posting third-quarter gross margins above 25%, extending the four-quarter climb. Would invalidate — Taiwanese monthly revenue flattening sequentially, or 2027 consensus growth of 49% and 61% being cut. Watch next — Monthly Taiwanese revenue disclosures in early September, then Ibiden's September-quarter results in late October. Valuation — Unimicron 65.3x trailing and 52.3x forward gross profit; Ibiden 40.0x and 33.4x; AT&S 20.1x and 14.7x.