Three years ago, Intel made a judgment that sent a shockwave through the semiconductor packaging industry at a technology launch event—glass substrate packaging will become the key route for next-generation advanced packaging. On July 25, Intel announced a strategic partnership with Lens Technology to accelerate the development of glass substrate packaging solutions.
After being hotly debated for three years and holding high expectations, is glass substrate packaging truly arriving?
Who Will Glass Substrate Packaging Disrupt?
The growth in AI computing power demand has driven the market expansion of high-performance chips. Due to its highly matched coefficient of thermal expansion (CTE) with silicon chips, ultra-high flatness, and low signal loss, glass substrates are considered the ideal material for next-generation chip packaging substrates.
Zhang Jihua, founder of Triassic (Guangdong) Technology Co., Ltd. and professor at the University of Electronic Science and Technology of China, told reporters from China Electronics News that glass has three application scenarios in the chip packaging process: first, using glass as a "glass carrier" for 2D packaging or 2.5D packaging. During the packaging process, the glass provides mechanical support and is removed after use. This process is already quite mature and very close to mass production levels. Second, using glass interposers to replace silicon interposers to reduce costs. Third, using glass packaging substrates to replace PCBs (Printed Circuit Boards) or other organic substrates.
Schematic Diagram of TSMC (Taiwan Semiconductor Manufacturing Company) CoWoS Process
If we draw an analogy with the CoWoS (Chip on Wafer on Substrate) technology developed by TSMC, the second and third types of applications mentioned here can be respectively mapped to: using glass to replace the W (Wafer, silicon wafer) or S (Substrate, organic substrate) in CoWoS.
Simply put, what glass substrates aim to replace is not the green circuit board inside a computer, but the "packaging substrate" layer between the chip and the circuit board. This layer determines whether the chip can be efficiently packaged and whether signals can be stably transmitted.
The Most Critical "Fragility" Issue Has Been Basically Resolved
Glass substrates sound promising—featuring a low dielectric constant, tunable coefficient of thermal expansion, and extreme dimensional stability and high flatness—but over the past few years, a core issue has constantly plagued the entire industry: glass is too brittle.
Fragility makes glass unable to withstand processing—edge stress concentration after through-hole processing makes it prone to cracking during lamination processes, and it cannot withstand bumps and collisions—chips using glass substrates are highly susceptible to failure when subjected to physical impacts.
Now, this issue has been basically resolved.
Yu Zongguang, Chief Scientist at the 58th Research Institute of CETC and Rotating Chairman of the Packaging and Testing Branch of the China Semiconductor Industry Association, told reporters from China Electronics News: "The issues of glass brittleness and easy cracking have currently been systematically optimized through four dimensions: material selection, process optimization, structural reinforcement, and process control. It can fully meet the strength requirements for industrial-level mass production, packaging, and terminal applications. Glass brittleness is no longer a core obstacle to industrialization."
After more than a decade of technological iteration, companies represented by Triassic and Tongge Micro have completed technological optimization from multiple dimensions: first, selecting high-strength special glass substrates suitable for semiconductor packaging to improve structural stability from the raw material end; second, eliminating the stress concentration problem after through-hole processing through proprietary etching and edge passivation processes; third, optimizing multi-layer lamination and bonding processes to match the mechanical properties of glass materials and avoid the risk of cracking during processing; fourth, establishing a full-process precision process control system to ensure the strength consistency and stability of mass-produced products.
Yu Zongguang stated that currently, TGV (Through Glass Via) glass substrate products mass-produced and submitted for sampling by leading industry enterprises have passed customers' stringent reliability tests, meeting the standards in multiple tests such as high and low-temperature cycling, mechanical shock, and bending adaptation. This means that glass can stably adapt to industrial applications in high-end scenarios such as chip packaging and optical modules, and the brittleness issue no longer restricts the implementation of large-scale mass production. The current core competitive barriers in the industry have shifted from "solving basic brittleness issues" to high-level competition in "high-precision through-hole yield, multi-layer interconnection processes, and large-scale cost control."
TGV Becomes the Key to Mass Production of Glass Substrate Packaging
After the "basic brittleness issue" hindering the mass production of glass substrate packaging is basically resolved, the next problem to be solved is the "high-precision through-hole yield" challenge. The yield of the TGV (Through Glass Via) process directly determines the overall panel yield and is the main bottleneck currently faced in the industrialization of glass substrate packaging.
As the only way for glass substrates to achieve vertical electrical interconnection, the performance of TGV directly determines packaging density and signal integrity; TGV involves technologies such as ultra-precision through-holes, high aspect ratio filling, and interface reliability control, which is the core technical differentiator between glass substrates and organic substrates. In the processing cost of glass substrates, TGV through-holes and metallization also account for the highest proportion of costs, with the cost share of these two links exceeding 40%.
Yu Zongguang stated that breaking through TGV process limitations and achieving mass production of glass substrates is a systematic project, requiring the comprehensive improvement of "process algorithms + process systems + equipment adaptation + yield control." TGV equipment can be procured domestically or customized to meet requirements, but the process recipes, process logic, yield control systems, and full-process integration capabilities adapted to domestic scenarios are core barriers accumulated over the long term.
The core breakthroughs that need to be achieved in this technology are concentrated in three aspects:
First, high-precision through-hole forming process, which is the first core barrier for TGV. Traditional mechanical and physical removal processes, laser direct ablation processing technology, and photosensitive glass induced pore-forming technology suffer from insufficient precision, rough through-hole sidewalls, and uneven depth, failing to meet the needs of high-end packaging. Laser Induced Deep Etching (LIDE) is considered the optimal technical path for batch manufacturing of large-size, high-density TGVs currently. This process adopts a processing strategy of "modification first, etching later" to form high-quality through-holes.
Second, high-reliability through-hole metallization process. After through-hole forming, a uniform, dense, and highly adhesive metal coating is the key to achieving stable conduction. In this link, the industry generally faces yield pain points, and it is difficult to achieve solid filling of through-holes.
Third, multi-layer RDL (Redistribution Layer) interconnection and bonding processes. High-end advanced packaging requires multi-layer RDL and high-density interconnection, but due to the low mechanical strength of glass and the large thermal mismatch with multi-layer wiring dielectrics, warpage or even tearing of composite substrates is the main issue.
Fragility is the most concerning issue in the use of TGV processes. "Copper leads need to be filled in glass through-holes, but the expansion coefficient of copper is much larger than that of glass. During the temperature rise, the expanding copper will crush the glass or destroy the circuits on the glass," Zhang Jihua stated. "To solve this problem, we are verifying various solutions, such as improving the strength and expansion coefficient of glass at the material level, or creating a flexible buffer layer in the middle of the glass at the process level."
2027 Will Be the Period of Order Release
Over the past two years, the entire industry has made numerous efforts to promote the maturity of glass substrate technology: through basic process research, it has achieved high-precision through-hole processing adaptation for multi-material glass; the upstream and downstream supporting industrial chains have gradually improved, the process routes have become clearer, and core yield issues such as uneven through-holes, metallization delamination, and lamination warpage have been effectively improved; scenario implementation has accelerated, and glass substrate technology has been successfully adapted in diverse application scenarios such as optical communication, MLED, AI chiplet integration, and RF packaging. Core processes that previously restricted industrialization, such as through-hole processing, metallization, multi-layer RDL interconnection, and bonding adaptation, have achieved significant iterative upgrades after years of concentrated research.
When Will Glass Substrate Packaging Be Mass-Produced?
Regarding this question, a consensus has basically been formed in the industry: 2026 will be the window for industrial verification, 2027 will see a gradual release of orders, and 2028 will enter the stage of volume ramp-up. Among overseas giants, Intel plans to achieve small-batch trial production in 2026 and scale up production in 2027; TSMC expects to start trial production in 2027 and achieve large-scale mass production in the second half of 2028. Some leading domestic enterprises have already built pilot production lines and achieved small-batch supply, steadily advancing towards large-scale mass production.
Yu Zongguang stated: "Glass substrate packaging technology is currently in a critical stage of transitioning from 'technology verification' to 'small-batch mass production.' This year is a 'critical verification period,' not the 'first year of comprehensive mass production.'"
From the perspective of the pace of industrial implementation, mid-to-high-end AI computing chips, heterogeneous chiplet integrated chips, MLED high-end display chips, and optical communication will be the first to achieve large-scale application of glass substrate packaging. The core reason is that these scenarios have the most urgent demand for high-frequency, high-speed, low-loss, high-flatness, and high-stability substrates, the performance bottlenecks of traditional organic substrates are the most prominent, the cost-effectiveness advantage of glass substrate substitution is significant, and the product verification cycle is shorter with a lower threshold for implementation.
In addition to application scenarios for mid-to-high-end computing chips, Zhang Jihua stated that glass substrates can also play a role in the fiber array unit (FAU) of optical modules, because the technical chain for producing the glass substrate structural components required in this scenario is shorter—it only requires drilling, without the need for filling and wiring, so it is expected to become the first type of product to be mass-produced. The function of FAU can be understood as a connector linking the optical module with external optical fibers—it can guide the light from the optical fibers into the optical module. Of course, 2D FAUs put forward new requirements in terms of substrate thickness, position accuracy, through-hole roundness, and special-shaped structures. The production line for producing FAUs using glass substrates is under construction, and such products are also in the verification stage, with production expected to start in 2027.
Poised for Full Localization
Looking ahead, global glass substrate packaging will usher in a growth scale of tens of billions of dollars. According to Omdia's calculations, the global market size for packaged glass substrates will reach $18.6 billion in 2026, and is expected to exceed $32 billion in 2030, with a compound annual growth rate of about 14.5%.
From the perspective of the current development status, key links in the TGV glass substrate industrial chain, including core processes, process technologies, and mass production equipment, are almost at the same starting line globally. Coupled with the continuous layout of Chinese enterprises, China has the opportunity to achieve full localization in this field.
Yu Zongguang stated that overall, China has already possessed international competitiveness in the TGV glass substrate track, with local leadership and overall parallel running. In comparison, overseas enterprises have formed a first-mover advantage through early patent layout, but their industrialization pace is conservative, process adaptability is weak, and costs are high; domestic enterprises have formed independent patent barriers and technological advantages in fields such as hybrid etching, multi-layer lamination, and glass-based overall packaging solutions, with multiple process indicators reaching or exceeding the levels of overseas peers.
However, in terms of high-end inspection equipment and special chemicals, it will take longer for domestic enterprises to catch up. Zhang Jihua stated that in terms of equipment, lasers, through-hole inspection, and plating solution analysis equipment used for glass substrate packaging mainly rely on imports, and there is currently a lack of mature mass-produced products domestically. Raw materials are mainly products from manufacturers such as Corning and SCHOTT. Localization is gradually advancing and has made gratifying progress.
Author | Ji Xiaoting Editor | Qiu Jiangyong Art Designer | Ma Liya Supervisor | Lian Xiaodong