Glass materials offer advantages such as high flatness, good dimensional stability, adjustable thermal expansion coefficient, low dielectric loss, minimal substrate loss, and suitability for rectangular panel processing, positioning them as a promising key substrate/interposer material for large-scale advanced packaging in AI/HPC.

Glass substrates are transitioning from thematic anticipation to industrial validation within the advanced packaging supply chain. In the context of Co-Packaged Optics (CPO), glass substrates are poised for near-term application in glass-based electrical interconnect substrates, with potential for longer-term extension towards glass optical waveguides and photonic integration.

Glass Substrates as the Ideal Material for Advanced Packaging Substrates/Interposers in the AI Era

Sustained strong demand for AI computing power is driving core components like high-end GPUs, ASICs, and HBM towards higher bandwidth, increased I/O density, and greater integration. Advanced packaging is evolving from a back-end manufacturing step into a platform for system performance optimization. As package sizes continue to increase, silicon interposers face growing challenges in scaling up due to constraints from single-exposure area limits of lithography tools, the layout efficiency of 12-inch wafers, defect probability, and cost-yield trade-offs. Concurrently, the limitations of traditional organic packaging substrates in high-frequency/high-speed interconnects, large-size packaging, thermal expansion matching, and warpage control are becoming more pronounced.

Industrialization Process Accelerates Significantly

Intel and TSMC are propelling advanced packaging-grade glass substrates into the industrial validation phase. In January 2026, Intel launched the world's first commercial CPU utilizing a glass core substrate, demonstrating the industrial feasibility of integrating glass materials at the packaging substrate level. For TSMC, its Chip-on-Package-on-Substrate (CoPoS) technology has progressed from initial feasibility studies to trial production validation. CoPoS production lines are expected to see a significant ramp in output between 2028 and 2029, indicating that glass substrates are moving from concept to practical verification within the advanced packaging ecosystem.

RF IPD and CPO Represent Fast-Moving Application Areas for Glass Substrates

For Radio Frequency Integrated Passive Devices (RF IPD), glass, with its high insulation, low dielectric loss, dimensional stability, and excellent high-frequency properties, has become a crucial substrate material. Companies such as YT Semiconductor and 3DGS have already achieved mass production of glass-based IPDs, with reliable validation in high-frequency, high-precision applications. Regarding CPO, glass substrates are expected to find initial application in glass-based electrical interconnect substrates in the short term, with the potential to extend towards glass optical waveguides and photonic integration over the longer term.

Core Process Challenges Lie in Raw Glass Sheets and Through-Glass Vias (TGV)

The manufacturing process for semiconductor-grade glass substrates includes raw glass sheet preparation, TGV formation, via wall metallization/copper filling, surface metallization, redistribution layer (RDL) formation, dielectric layers and multilayer interconnects, surface treatment, and reliability testing. Among these, the raw glass sheet determines flatness, thickness uniformity, low defect rates, and thermal expansion matching capability. TGVs, responsible for vertical interconnects between layers, are the key process that elevates glass substrates from structural support materials to three-dimensional interconnect platforms.

Industry Chain Focus on Raw Materials, Precision Processing, and Auxiliary Materials

The raw glass sheet segment is dominated by specialty glass companies. Overseas leaders like Corning, Schott, AGC, and NEG possess significant accumulated expertise. Domestic companies with a material foundation include Qibin Group, Gobige, Linuo Pharmaceutical Packaging, Kaisheng Technology, and Caihong Co., Ltd. The precision processing segment warrants attention for companies with capabilities in TGV formation, via metallization, copper plating, RDL patterning, and panel-level processing. Companies like Woge Optoelectronics and BOE A have advanced pilot lines for glass-based packaging substrates, sample validation, and small-batch production. In the auxiliary materials segment, material suppliers such as Tiancheng Technology have entered the customer validation and small-order stage.

Investment Recommendations

Within the raw materials segment, attention is advised on companies with potential for import substitution, such as Qibin Group, Gobige, Linuo Pharmaceutical Packaging, Kaisheng Technology, and Caihong Co., Ltd. For the precision processing and auxiliary materials segments, focus is suggested on companies demonstrating capabilities in TGV, copper plating, RDL, panel-level processing, and key material validation, including Woge Optoelectronics, BOE A, and Tiancheng Technology.

Key Risk Factors

Risks include slower-than-expected industrialization progress, delays in key process development, and setbacks in customer validation and order conversion.