The ABF Substrate Supply Chain Behind AI Accelerators

ABF becomes more valuable as the package gets harder to build

ABF is the insulating layer inside high-density organic package substrates. Ajinomoto describes it as a thermosetting film built from organic epoxy resin, a hardener and inorganic microparticle filler. Substrate manufacturers laminate the film, create microscopic vias, deposit copper and pattern fine interconnects before repeating the process across multiple build-up layers. [3]

This puts Ajinomoto near the beginning of a long conversion chain.

The distinction matters for investors because additional ABF output does not automatically create additional accelerator substrate capacity.

Producing an advanced substrate requires repeated lamination, laser drilling, plating and fine-line patterning. As the package grows, more area has to pass through these processes. Additional build-up layers increase the number of manufacturing steps. Finer wiring raises process difficulty and yield sensitivity. Larger packages also make warpage and dimensional stability harder to control.

IBIDEN has explicitly linked AI server growth with larger and more multilayered substrates. Its 2026 investment program therefore represents considerably more than ordinary capacity replacement. It is an expansion of the manufacturing infrastructure required to turn dielectric film and copper into something an advanced GPU or ASIC can actually use. [1]

Nan Ya PCB is describing the same transition from another part of the market. In its May 2026 investor material, the company said it was developing next-generation ABF substrates for AI server ASICs as hyperscalers expanded data center capital expenditure. It is also targeting substrates for high-end networking equipment used to move data between increasingly large AI systems. [2]

The important signal is that both GPU growth and custom ASIC growth converge on the same substrate manufacturing processes.

The bottleneck extends in both directions from Ajinomoto

Ajinomoto is unusual because ABF sits deep inside the package while remaining technologically important to fine-pitch routing. But treating Ajinomoto as the entire ABF investment story misses two different dependency layers.

Downstream, substrate manufacturers including IBIDEN and Nan Ya PCB have to convert ABF into qualified, high-layer-count products. Other major FC-BGA and advanced substrate producers, including Unimicron, Kinsus and Shinko Electric, occupy similar positions in this manufacturing layer. Their exposure is not simply to semiconductor unit volumes. It is increasingly tied to package area, layer count, wiring density and the amount of processing required for each accelerator.

That makes substrate demand capable of growing faster than accelerator shipments themselves. A package generation that becomes larger and requires more build-up layers consumes more substrate process capacity even if the number of finished chips does not increase proportionally.

Upstream from Ajinomoto, the dependency becomes more chemical. Ajinomoto's own description of ABF identifies epoxy resin, a hardening system and inorganic microparticle filler as fundamental ingredients. [3] Those materials have to deliver electrical insulation, low thermal expansion, processability and mechanical stability at increasingly demanding geometries.

This upstream layer is easier to overlook because the raw material value per package can be small relative to the finished accelerator. That does not make it economically irrelevant.

A useful supply-chain distinction is the difference between cost share and production criticality. A material can represent a modest portion of a substrate maker's total costs while still being difficult to replace inside a qualified manufacturing process. Conversely, a substrate manufacturer can buy relatively inexpensive dielectric and chemical inputs but create significant economic value through manufacturing precision, yield management and customer qualification.

That asymmetry is why the ABF chain should not be analyzed by revenue size alone.

The second-order AI exposure is substrate process capacity

The obvious AI semiconductor exposures remain accelerator designers, foundries and HBM producers. ABF substrates introduce a different group of companies whose economics are connected to the physical complexity of those chips.

Ajinomoto benefits from greater demand for advanced build-up dielectric. IBIDEN and its peers are exposed to the manufacturing burden created when AI packages become larger and more complex. Nan Ya PCB's move toward next-generation AI ASIC substrates shows that this demand is broadening beyond conventional GPU architectures into hyperscaler-designed silicon. [2]

The common dependency is the substrate process itself.

That makes one distinction especially important for investors: growth in ABF demand and growth in finished substrate capacity are not interchangeable. If dielectric film supply expands faster than qualified substrate manufacturing, the bottleneck remains at the converter. If substrate manufacturers expand aggressively, attention can move upstream toward the specialized resins, fillers and other materials required to sustain higher production volumes.

Conclusion

The ABF supply chain behind AI accelerators is not a single-company story. Ajinomoto supplies a critical dielectric, but AI packaging demand becomes economically concentrated again at substrate manufacturers such as IBIDEN and Nan Ya PCB, where ABF must be transformed through increasingly intensive build-up and copper-patterning processes.

The most important variable is therefore not simply how many AI accelerators are produced. It is how much substrate area, how many layers and how much process capacity each new generation consumes. As AI packages become larger and more complex, that manufacturing burden pushes the investment exposure both downstream into advanced substrate producers and upstream into the specialized chemical materials from which ABF itself is made.

Sources

1. "Notice Regarding Capital Investment Plan for High-Performance IC Package Substrates," IBIDEN Co., Ltd., February 3, 2026, https://www.ibiden.com/company/2026/02/notice-regarding-capital-investment-plan-for-high-performance-ic-package-substrates.html

2. "2026 Investor Conference Presentation," Nan Ya Printed Circuit Board Corporation, May 6, 2026, https://www.nanyapcb.com.tw/nypcb/images/InvestorRelations/FinancialReport/NYPCBENG20260506.pdf

3. "Ajinomoto Build-up Film (ABF)," Ajinomoto Group, https://www.ajinomoto.com/innovation/our_innovation/buildupfilm

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