Glass substrates, with their superior properties, are gradually emerging as a next-generation medium for advanced packaging. The current TGV (Through Glass Via) glass substrate technology is at a historic juncture, transitioning from fundamental laboratory research to mass production engineering, with overseas progress leading and domestic efforts accelerating to catch up. It is recommended to closely monitor the progress of downstream customer validation and the construction of mass production lines. Attention should also be paid to related companies in upstream raw glass sheet supply, equipment, other materials, and processing/manufacturing segments. The main views are as follows:

Glass Substrate: A New Advanced Packaging Material

As Moore's Law evolution slows, advanced packaging has become the core path for enhancing chip integration and system performance in the post-Moore era. Traditional organic substrates face physical bottlenecks such as warpage and deformation, limited wiring density, and signal loss in large-scale integration. Against this backdrop, glass substrates, leveraging their excellent characteristics including low dielectric constant, low dielectric loss, high flatness, high chemical stability, and a thermal expansion coefficient highly compatible with silicon, are progressively becoming the new advanced packaging medium.

Industrialization Accelerates: TGV Interposers and TGV Glass Core Substrates Develop in Parallel

Based on glass substrates, two advanced packaging solutions are emerging: replacing TSV (Through-Silicon Via) and replacing IC packaging substrates.

1) TGV Interposers replacing traditional TSV interposers: Intel showcased a physical sample combining EMIB packaging with glass substrates at NEPCON Japan earlier this year, utilizing a dual EMIB bridge structure to double the carrying capacity. TSMC's CoPoS solution adopts the TGV interposer route, "transforming circles into squares" to improve substrate utilization, with pilot line equipment delivered in February, production line construction expected to complete in June, and mass production slated to begin in 2028. Samsung is actively testing the application of glass substrates in next-generation HBM4 memory packaging to enhance stacking density and thermal performance.

2) TGV Glass Core Substrates replacing traditional IC packaging substrates: Intel is leading globally in commercialization, having shipped the world's first Xeon 6+ Clearwater Forest server processor equipped with a glass core substrate in January. Samsung Electro-Mechanics' pilot line is already operational, and it began supplying glass substrate samples for Apple's AI server chip "Baltra" in April.

Furthermore, in the field of CPO (Co-Packaged Optics), glass substrates have gradually become the preferred material for packaging-level optical waveguide integration technology in recent years due to their high transparency across a broad spectrum, low dielectric loss, high dimensional stability, and good process compatibility.

Key Technologies: TGV as the Core, Metallization Filling and RDL Determine Electrical Connection Quality

Core TGV processes include raw sheet manufacturing, TGV via formation, metallization filling, and RDL (Redistribution Layer). The fabrication of TGV glass vias is the core process in glass substrate packaging. Compared to traditional methods like physical drilling, laser direct ablation, or photosensitive glass, the Laser-Induced Deep Etching (LIDE) process offers advantages such as high aspect ratio, high processing precision, and efficiency, and is considered the optimal technical path for current large-scale, high-density TGV mass production. Additionally, TGV metallization filling and RDL technologies primarily achieve metal filling inside the vias and fine wiring on the surface, which are key to determining the quality of electrical connections on the glass substrate.

Current Status: Overseas Leads, Domestic Market Accelerates to Catch Up

Benefiting from earlier TGV technology accumulation by overseas semiconductor giants and the supply advantages of high-quality raw glass sheets from companies like Corning, overseas TGV progress is ahead. Looking at the industry chain: 1) Raw Sheets: Overseas giants like Corning, Schott, and AGC hold the vast majority of market share, but domestic substitution is accelerating. 2) Equipment: Including laser equipment, electroplating equipment, etc. According to company announcements, DR Laser has achieved comprehensive coverage of wafer-level and panel-level TGV packaging laser technology; Dongwei Technology has delivered and successfully accepted TGV electroplating equipment. 3) Other Materials: Including etching additives (e.g., Techwin), surface cleaning agents (e.g., Jianghua Microelectronics), etc.

Risk Analysis

Potential risks include slower-than-expected progress in TGV technology, a slowdown in AI capital expenditure, intensifying industry competition, and slower-than-expected domestic substitution.