Glass Substrates
Glass is one of the most common materials, yet it has rarely played a leading role in the semiconductor industry.
Over the past six months, investments in production lines and pilot lines for glass substrates have been successively launched from Gimcheon in Gyeongsangbuk-do, South Korea, to Bengbu, Anhui, China, and Georgia, the United States, with amounts often reaching hundreds of millions. These capital bets are all placed on the same endeavor: drilling millions of micron-level through-holes in glass, filling them with copper, and routing dozens of layers of circuits, enabling glass to take over part of the work of organic substrates and become the foundation for next-generation advanced packaging.
The contradiction lies here as well—no manufacturer has yet achieved stable, large-scale commercial mass production of this technology. GlaSSEM, a joint venture between Samsung Electro-Mechanics and Sumitomo Chemical, has delayed its mass production milestone from the second half of 2027 to 2028; industry research indicates that the yield rate for glass interposers currently remains below 40%.
As the mass production timeline is repeatedly pushed back, investments have not ceased, and glass substrates have advanced to the autumn of 2026 amidst this contrast.
01. A Component Manufacturer Bets 347 Billion KRW
On September 21, South Korean component manufacturer JNTC signed an investment memorandum of understanding with the Gyeongsangbuk-do Provincial Government and the Gimcheon City Government. The company plans to invest approximately 347 billion KRW (about 290 million USD) between 2027 and 2030 to build a new TGV glass substrate production line in the Gimcheon 1st General Industrial Park, creating 430 new jobs. According to South Korea's Electronic Times, the project covers an area of about 30,000 pyeong (approximately 100,000 square meters), and this investment is equivalent to 140% of JNTC's total equity.
Founded in 1996, JNTC started as a company manufacturing connectors and camera module components. The leap from connectors to semiconductor materials is significant, yet not unexpected within the context of South Korea's industrial landscape: glass substrates are regarded by the government and multiple large enterprises as core materials for the AI semiconductor era. Gyeongsangbuk-do has described this signing as the establishment of a production base for core AI semiconductor materials.
For JNTC, TGV is a process that must be conquered from scratch—drilling micron-level through-holes in glass and completing metal filling to enable signal transmission through the glass between upper and lower layers. The production line is scheduled to commence construction in 2027, followed by phased expansion. Equipment introduction, process validation, and customer certification—every step requires continuous investment, making the 347 billion KRW merely an entry ticket.
02. Glass Is Not Yet the Protagonist, So Why Is Everyone Betting on It?
Zooming out, glass is not currently the protagonist in the semiconductor substrate market.
The mainstay for high-end chip packaging is organic substrates; ABF substrates are used for computing chips like CPUs and GPUs, while BT substrates cover RF and memory chips; ceramic substrates are often chosen for power devices and high-temperature scenarios; in 2.5D packaging like TSMC's CoWoS, a silicon interposer is placed between the chip and HBM. Glass substrates are not yet mainstream among these options: the supply chain for organic substrates has been running for two decades, the silicon interposer is backed by an established foundry ecosystem, whereas for glass substrates, even the processing equipment, chemical materials, and inspection standards are still being built.
△Note: Assisted by AI
However, the number of manufacturers betting on it is increasing, driven by the expanding packaging area. Industry data shows that AMD's MI300 has a packaging size of approximately 75×75 mm, NVIDIA's Blackwell is about 73×81 mm, and future planned products are rumored to exceed 150×100 mm.
The larger the substrate, the harder it is to control warpage. The coefficient of thermal expansion (CTE) for organic substrates is typically above 10 ppm/°C, while silicon chips are only at 2-3 ppm/°C. When the temperature changes, the deformation of the two is not synchronized, making large-area substrates prone to bending. The CTE of glass is in the range of 3-5 ppm/°C, which is close to that of silicon, and its flatness is far superior to that of organic materials, enabling better dimensional stability in large-area packaging.
△Note: Assisted by AI
Glass also has advantages at the electrical level. It has a low dielectric constant and good insulation, resulting in lower loss and crosstalk when high-frequency signals pass through, which is a plus for increasingly fast chip interconnects; its surface roughness can be made lower, theoretically supporting higher-density routing, and BOE has already produced 20-layer structural samples on its pilot line. The raw material, glass itself, is cheap, but the processing is difficult: drilling, copper filling, and lamination—the yield rate of each process is driving up the overall cost. This is precisely the crux of why glass substrates are repeatedly mentioned yet remain difficult to mass-produce.
03. Over the Past Six Months, the List of Strategic Deployments Is Growing
AI computing chips are making packaging areas increasingly larger, pushing organic substrates to their limits in high-density, large-area scenarios. Glass substrates have become one of the few alternative paths repeatedly validated. Over the past six months, strategic deployments surrounding TGV glass substrates have been intensively launched globally.
South Korea has seen the most actions. The progress of Samsung Electro-Mechanics has attracted the most attention: on July 2, it signed a joint venture agreement with Sumitomo Chemical, a subsidiary of Sumitomo Chemical. The new company is named GlaSSEM, with Samsung Electro-Mechanics holding a 66.2% stake, and the mass production target set for 2028. However, according to The Elec, the glass substrates previously submitted by Samsung Electro-Mechanics to customers failed reliability assessments, equipment orders were delayed three times, and new samples need to be produced for re-evaluation. On the materials front, The Elec reported that Samsung Electro-Mechanics' cooperation with Solbrain has expanded from etchants to copper electroplating solutions and CMP slurries, covering the three key chemical materials for glass substrate manufacturing.
At the KPCA Show 2026 from September 9 to 11, South Korean equipment manufacturer Taesung exhibited physical TGV samples of 2.0 mm thick glass core substrates, having completed the entire process of etching, cleaning, and electroplating.
Absolics, a subsidiary of SKC, has built the world's first mass production line for glass substrates in Georgia. In late August, it raised 401.1 billion KRW through a capital increase, with SKC subscribing to 281 billion KRW of it. The funds are allocated to customer certification and yield improvement.
Progress in mainland China is concentrated on pilot lines and sample submissions. On September 7, BOE disclosed in an investor relations event that its glass-based packaging substrate pilot line achieved fully automated equipment integration in the first half of 2026. With a designed monthly capacity of 1,000 panels, it has integrated the entire process flow, including TGV drilling, deep-hole copper filling, and routing. The 20-layer (9-2-9 structure) large-size samples completed in 2025 have passed multiple reliability tests and been submitted to customers, with a cumulative investment of approximately 1.4 billion CNY. In May, BOE signed a memorandum of understanding with Corning to conduct joint development on glass-based packaging substrates.
On the evening of July 24, Lens Technology announced that its subsidiary Lens International (Hong Kong) signed a memorandum of understanding with Intel, with TGV advanced packaging as the key focus of their cooperation. Lens Technology is planning a 30,000-square-meter dedicated TGV factory building, which is expected to commence production by the end of 2026.
On the evening of July 27, Triumph Science & Technology announced its plan to invest approximately 150 million CNY to build a TGV advanced packaging glass pilot line in Bengbu. The company initiated key technology R&D for TGV through-holes and metal filling in 2024. The pilot line will be built within the factory area of the second phase of the Ultra-Thin Glass (UTG) project in the Bengbu High-tech Zone, used for key process optimization, product trial production, and customer validation.
Taiwan, China is also deploying production lines. On July 30, the board of directors of AU Optronics approved a capital expenditure of 8.641 billion TWD (approximately 1.83 billion CNY) for TGV and RDL production lines, as well as a glass substrate pilot line. At SEMICON Taiwan in late August, AU Optronics showcased glass core substrate samples, with the glass materials sourced from Corning.
On the same day, Chime Ball Technology announced the completion of the region's first TGV metallization foundry line. It has received sample orders from international glass material manufacturers, Mini LED enterprises, and leading substrate manufacturers, and plans to cooperate with mainland substrate manufacturers and the silicon photonics supply chain.
Aligning these public milestones, the progress of glass substrates is roughly as follows: samples and pilot lines are emerging intensively, customer certification has become a common bottleneck, and the mass production time window is concentrated between 2027 and 2028. Equipment manufacturers are beginning to receive actual orders, the scope of cooperation among material manufacturers is expanding, and the binding between substrate manufacturers, equipment manufacturers, and material manufacturers is taking shape.
Before glass substrates can become stably supplied packaging substrates, they still need to pass two hurdles: reliability validation and yield rate. These are also the most noteworthy variables in the next stage.
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