TSMC Teams Up with Ibiden and Innolux to Push CoPoS — Reportedly Flooring the Accelerator in Glass Substrates
To meet robust AI chip demand, TSMC is not only ramping CoWoS advanced packaging capacity but has, for the first time, disclosed progress on its "glass substrate" technology. The company further signaled that the next-generation advanced packaging battle is gradually shifting from CoWoS to CoPoS (Chip-on-Panel-on-Substrate), as it moves to build out a complete ecosystem ahead of the curve.
According to equipment-side sources, TSMC recently shared a "Glass Substrate Development for CoWoS" program with its supply chain. It has confirmed a partnership with ABF substrate giant Ibiden and panel maker Innolux to jointly validate the feasibility of introducing glass substrates into next-generation CoWoS advanced packaging. The aim is to address the warpage, thermal management, signal transmission, and power delivery challenges that loom over future large-die AI chip packaging.
At the same time, the move reflects rapidly intensifying customer demands around technical specifications and capacity, as well as mounting competitive pressure from Intel and Samsung Electronics. That pressure has finally pushed TSMC—long known for advancing R&D on a "cautious, not aggressive" basis—to step on the accelerator.
Glass substrates are viewed as a key technology for the "post-CoWoS era" thanks to their low warpage, low thermal expansion, high rigidity, and excellent signal and power-delivery characteristics. Supply chain sources say the three-way collaboration among TSMC, Ibiden, and Innolux, together with simulation validation, has shown that glass substrates can improve the package-warpage indicator COP (Chip on Package) by 16%, lower the effective coefficient of thermal expansion (Effective CTE) by 19%, and raise the effective modulus (Effective Modulus) by 31%.
On power integrity, resistance fell by 27% and inductance by 42%. Overall, introducing glass substrates can deliver a marked improvement in package performance (PKG Improvement).
TSMC nonetheless stressed that continued research and validation are still needed on glass thickness (Glass Thickness) and large-size CoWoS layout (Large-size CoWoS Layout). While full-scale mass production remains some distance away, this marks the first time TSMC has publicly disclosed joint glass-substrate validation results with Ibiden and Innolux—signaling that glass substrates have formally entered the industrialization-validation phase.
Industry observers added that the 16% COP improvement indicates package warpage is being effectively controlled. As AI GPU dies grow ever larger—with NVIDIA's GB200, GB300, and the now-ramping Rubin platform all expanding in package size—the importance of package flatness and warpage control has risen sharply. The performance glass substrates show in reducing warpage should help lift the yield and reliability of large packages.
In addition, the 19% reduction in SBT effective CTE shows improved matching between the glass material and the silicon die.
Today, silicon's CTE differs substantially from that of conventional organic substrates, making it prone to stress under temperature swings that can compromise package reliability. By contrast, glass has a CTE closer to that of silicon, which helps reduce thermal stress and mitigate cracking and solder-joint fatigue. The 31% gain in effective modulus means higher overall rigidity, providing better structural support. In particular, as HBM stack heights keep increasing, substrate rigidity is becoming a critical condition for supporting large packages.
The test sample TSMC used this time featured a 0.8mm glass core substrate, a package spec of 5x reticle CoW, and an overall package size of 85×110mm—an AI GPU package-class footprint. TSMC specifically emphasized "No SeWaRe (severe warpage) & Delamination," meaning no severe warpage or delamination/peeling—both yield killers—occurred during testing.
For glass substrates, material bonding reliability has always been a key challenge, so maintaining a stable structure at large package sizes demonstrates considerable progress in technical maturity.
Another focus of the program was the comparison between Glass-SBT and Organic-SBT. TSMC noted that Glass-SBT achieves "thin but better COP," whereas Organic-SBT shows "thick but worse COP"—glass substrates can stay thinner while simultaneously improving package flatness and reliability.
The partner roster also hints at the direction of the future supply chain.
Ibiden currently sits in the critical substrate supply chain for NVIDIA and AMD AI chips and is regarded as a key player in industrializing glass substrates. It previously announced a ¥500 billion investment to expand its new Ono plant in Gifu Prefecture, dedicated to high-end packaging substrates for AI servers—underscoring its strong ambitions in the AI advanced-packaging market. Innolux's inclusion on the partner list is likewise seen as an important step toward staking out the next-generation glass-substrate battlefield.
Industry sources say the biggest challenge for glass substrates is not the glass itself but Through Glass Via (TGV) technology. Because glass is fundamentally an insulator, tens of thousands of TGVs must be formed to create vertical conductive paths before signal and power transmission becomes possible.
Glass is also both hard and brittle, making it prone to micro-cracks during processing that can affect reliability and yield. As a result, via forming, copper-fill quality, and long-term thermal reliability are considered the three core hurdles to mass-producing glass substrates.
Separately, Intel began investing in glass-substrate R&D more than a decade ago and is regarded as the earliest and deepest player globally. Its glass-substrate pilot line in Arizona is gradually moving toward commercialization, and Intel is aiming to win AI GPU and ASIC customer orders through glass substrates and ultra-large chiplet packaging.
Samsung Electro-Mechanics (Semco) established a glass-substrate pilot line in 2025 and has set up a joint venture with Japan's Sumitomo Chemical group to build out a glass-substrate supply chain ahead of the market.
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