TSMC CoPoS debut in 2029 to skip glass substrate, sources say

TSMC's first-generation CoPoS packaging platform will not use glass substrates, contradicting the narrative behind a speculative rally in Taiwan tech stocks.

TSMC's first-generation CoPoS (Chip-on-Panel-on-Substrate) packaging platform will not use glass substrates, and the company never considered a glass interposer for the technology, supply chain sources said — contradicting the market narrative that has fueled a speculative rally in Taiwan technology stocks.

"Market participants have broadly assumed glass substrates are a core component of CoPoS, but the first-generation roadmap tells a different story," a person familiar with TSMC's packaging plans said, asking not to be identified discussing non-public information.

CoPoS is expected to enter mass production in the first half of 2029, the sources said, later than the second half of 2028 timeline previously cited by industry researchers. Samsung Electro-Mechanics, Japan's Toppan, and other substrate makers have been developing glass-core substrates and have begun submitting engineering samples to TSMC, the sources added. Glass-core substrates sit beneath the interposer layer and serve as the package's mechanical carrier, distinct from the glass interposer that sits between the chip and substrate — a component TSMC never evaluated for CoPoS.

The clarification threatens to deflate a speculative rally in Taiwan-listed stocks tied to the glass substrate thesis. The global FO-PLP and glass substrate market is projected to grow more than tenfold to $8.1 billion by 2030 from $650 million in 2024, according to Counterpoint Research, with AI and HPC applications accounting for 45.6% of that total. But the first-generation CoPoS timeline suggests meaningful glass substrate revenue from TSMC's platform remains years away, potentially leaving suppliers that have rallied on the narrative facing a repricing.

The Glass Substrate Timeline

The glass substrate push is real but unfolding on a longer horizon than markets have priced. Intel added glass substrates to its advanced packaging roadmap in 2023 and demonstrated a sample combining its EMIB technology with a glass-core substrate at NEPCON Japan in January. TSMC's own glass substrate plans target a pilot line at subsidiary VisEra this year, trial production in 2027, and volume production in the second half of 2028, according to Counterpoint Research. But the first-generation CoPoS products rolling off that line will not incorporate glass, the sources said.

The distinction between glass-core substrates and glass interposers is critical. Glass interposers sit directly beneath the chip, handling high-speed interconnects between GPU and HBM memory. Glass-core substrates sit below the interposer, providing mechanical support and connection to the printed circuit board. TSMC evaluated neither for first-generation CoPoS, the sources said.

Intel's EMIB Challenge

The clarification comes as Intel challenges TSMC's dominance in advanced packaging. Google's next-generation TPU, codenamed Humufish, has selected Intel's EMIB-T technology over TSMC's CoWoS, according to SemiAnalysis — a notable defection from the industry-standard packaging platform. EMIB-T embeds small silicon bridges only where chip-to-chip connections are needed, avoiding the reticle-size constraints that limit CoWoS-S to roughly 3.3 times the reticle limit.

TSMC's CoPoS platform is designed to address those same constraints by moving from round wafers to 310-by-310-millimeter square panels, boosting substrate utilization to as much as 75%. But without glass substrates in the first generation, CoPoS will initially rely on organic materials — the same substrates that suffer from warpage issues as package sizes grow. Nvidia's Blackwell GPU already spans about 3.3 times the reticle limit, and the next-generation Vera Rubin is expected to reach four times that limit, according to TrendForce.

Investment Implications

For investors, the key question is which companies benefit from the first-generation CoPoS architecture and which are betting on a glass-substrate adoption curve that may take longer to materialize. Samsung Electro-Mechanics, Toppan, and other substrate suppliers have submitted engineering samples for glass-core substrates, suggesting they are positioning for later CoPoS generations. But near-term revenue from TSMC's panel-level packaging will flow to organic substrate suppliers, not glass specialists.

TSMC shares have gained 42% over the past 12 months, supported in part by optimism around its advanced packaging roadmap. The CoPoS clarification could introduce a more nuanced view of the timeline, separating the structural growth story from the speculative premium attached to glass substrate exposure. East Asia — Taiwan, Japan, and China — is expected to hold 84.8% of panel-level packaging capacity by 2030, according to Counterpoint Research, meaning the regional supply chain buildout continues regardless of the first-generation material choice.

This article is for informational purposes only and does not constitute investment advice.