Broadcom owns its substrate plant; everyone else in AI is renting

Broadcom semiconductor chief Charlie Kawwas walked Deputy Prime Minister Gan Kim Yong through a 95,000 sq m plant in Jurong Lake District on 29 September, opening Singapore's first high-end substrate line months ahead of schedule ¹². The joint venture behind it, Advanced Substrate Technologies (AST), had declared the build complete a day earlier ³.

The line Broadcom keeps for itself

Owning means co-owning. AST belongs to Toppan Holdings and Broadcom, and the manufacturing technology is Toppan's, developed at and run alongside its main production hub in Niigata ⁴⁵. Broadcom is the anchor tenant: first output goes to Tomahawk switches and the custom AI accelerators called XPUs ⁴.

The motive is a pandemic scar. "We were getting wafers, but we were keeping those precious, expensive wafers waiting for substrates," Kawwas said↗ ⁴. High-value manufacturing begins by late 2026 ⁴⁵.

Everyone else pays deposits

Rivals rent. Samsung Electro-Mechanics' board approved 6.78 trillion won, about $4.99 billion, this week, its largest bet ever in a single product category, with unnamed big-tech customers supplying part of the capital and guaranteeing future volume ⁶. Demand for its substrates runs 50 percent ahead of capacity, and prices rose 30 percent in August ⁶.

Ibiden is spending about 500 billion yen to lift output toward 2.5 times current levels ⁶. Nvidia, AMD and hyperscalers are locking in ABF substrate capacity through 2028 ⁷. Every one of those lines feeds on insulating film from Ajinomoto, a seasoning company holding roughly 95 percent of supply ⁶.

Owning looks modest by comparison. Toppan never disclosed the Singapore bill; Japanese media put the first phase near 50 billion yen↗, S$405 million, with expansion expected past 100 billion ¹. Investment Monitor asked AST for the figure; none came ⁵.

The demand side is thinning

The risk sits with customers. China, Hong Kong included, fell from 32 percent of Broadcom revenue in fiscal 2023 to 17 percent in fiscal 2025, from $11.53 billion to $11.16 billion, while the total climbed from $35.82 billion to $63.89 billion ⁸¹⁰.

The growth all shipped elsewhere. Beijing's state-asset regulator has spent weeks surveying Broadcom switches in state-run data centers, where they may account for up to 90 percent of equipment, per a Financial Times report Reuters could not verify↗ ⁹. Any scale-back guidance would be informal and preliminary ⁹.

December decides

Hock Tan settles capital allocation at Broadcom's December board meeting, with dividends and buybacks beside a $10 billion repurchase authorization that expires 31 December↗ ⁸. Watch two things: Chinese guidance reaching past state-run sites, or work shifting at one of the six custom-chip customers the line was built to serve ⁸.

If that book holds, Broadcom owns its bottleneck outright. If it thins, it owns a very clean factory waiting for wafers.