IC packaging substrates
BOTTLENECKNittobo's control of T-glass cloth constrains ABF substrate output, with new capacity not arriving until 2027 and a deficit projected from H1 2026.
Multi-layer organic, glass, or ceramic substrates providing die-to-board interconnect for packaged AI chips. Layer count and wiring density limit I/O bandwidth and power delivery to accelerators. Unimicron leads ABF supply with the top five holding ~74%; the hard constraint is Nittobo’s ~90% grip on T-glass cloth, with new capacity not online until 2027 and an ABF deficit projected from H1 2026.
Why the concentration exists
Glass and ceramic cores are emerging as alternatives, and they relax a different constraint. Warpage in advanced packages is driven by the coefficient-of-thermal-expansion mismatch between silicon at 2.6 ppm/°C and the surrounding mold compound at 7 ppm/°C, and a new non-photosensitive polyimide from Hitachi Dupont Microsystems reduced that warpage by 79% on silicon substrates and 95% on ceramic substrates. Glass cores take a different route, because they can be made flat enough to support direct copper-to-copper hybrid bonding, which organic cores cannot. That property matters because hybrid bonding is the densest interconnect scheme currently being industrialized for AI accelerators.[5][7]
What the evidence shows
Protracted qualification cycles of 12–18 months inhibit rapid substitution when supply tightens.
indexbox.ioZhen Ding is committing over US$1 billion by 2027 to become a global supplier of high-end substrates.
yolegroup.comWho supplies it
Unimicron Technology is the reference supplier on the substrate-maker side. The company is a subsidiary of United Microelectronics Corporation, was founded in 1990, and has held the No. 1 ranking among global substrate suppliers by market share for nine consecutive years since 2016, and is the world's largest IC carrier board supplier. Unimicron is gearing up for a strong rebound in 2025, driven by surging demand for high-end ABF substrates used in cloud-based AI applications, and Unimicron and Nan Ya PCB profits were boosted in December 2025 due to AI demand. The company will invest NT$30 billion (US$981.03 million) to set up a new plant in Taiwan dedicated to production of IC substrates with high layer count and large area for AI applications, and runs annual R&D spending of about 1% of revenue, which grew from NTD 6.48 billion in 2019 to NTD 15.84 billion in 2022.[4][2][3][12][8][9][13][11]
Who controls it
No independently verified market-size figure is published for this node yet.
Where it sits in the stack
Takes in: ABF dielectric film (Ajinomoto sole ABF film supplier), T-glass fibre cloth, copper foil, laser via drilling
Sends on: High-layer-count organic or glass substrate for flip-chip packaging
What to watch
Glass core substrates are the architectural alternative with the clearest dated milestones, and several land in 2026. SK Absolics is targeting mass production of glass substrates in 2026, and Absolics, a US subsidiary of South Korean SK Group, announced it will manufacture glass-core package substrates and TGV-interposers in 2026, with Absolics already supplying mass-production samples to AMD as of January 2026. Intel debuted the first sample combining EMIB packaging with a glass core substrate at NEPCON Japan in January 2026, achieving No SeWaRe (no micro-cracks), measuring 78 mm × 77 mm with roughly 1,716 mm² of silicon area, and Intel's ATTD team has been working on glass substrates since 2014. Samsung and Rapidus are expected to roll out glass interposer solutions. TSMC announced its chip-on-panel-on-substrate products are planned to be shipped in late 2028 with a glass panel size of 310 mm × 310 mm.[6][1][10][14]
Related nodes
Sources
- edge-ai-vision.com · 2024-09-09T08:02:12
- digitimes.com · December 2025
- digitimes.com · Jun 20, 2025
- digitimes.com · Jun 2, 2023
- semiengineering.com
- insights.trendforce.com · January 2026
- semiengineering.com
- en.wikipedia.org
- nextpcb.com · 2026
- 3dincites.com · Dec 01, 2025
- uniflex.com.tw
- uniflex.com.tw · 2022
- theisig.com
- photoncap.net · January 2026
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