Through-Glass Vias (TGVs): The Foundation of Next-Generation Semiconductor Packaging
As semiconductor devices continue to evolve beyond traditional Moore's Law scaling, innovation is increasingly shifting toward advanced packaging. Technologies such as heterogeneous integration, chiplets, photonics, and high-frequency RF systems demand glass substrates for advanced packaging that deliver exceptional electrical performance while enabling high-density interconnects.
Through-Glass Vias (TGVs) have emerged as a key enabling technology for these advanced packages. By combining vertical electrical interconnects with the unique properties of glass, TGVs provide a platform for building smaller, faster, and more efficient electronic systems.
At 3DGS Inc., TGV technology forms the foundation of our glass-based packaging platform for RF, photonics, AI infrastructure, aerospace, defense, and other high-performance applications. Learn more through our Technology Platforms page and the related subtopic for Integrated Passive Devices (IPD).
What is a Through-Glass Via?
A Through-Glass Via (TGV) is a metallized vertical electrical connection that passes through a glass substrate, creating an electrical path between circuits on opposite sides of the substrate. TGVs enable three-dimensional routing while preserving the excellent electrical characteristics of glass.
TGVs are commonly incorporated into glass interposers, Integrated Passive Devices (IPDs) RF modules, MEMS, sensor packages, and photonic assemblies, where signal integrity and package density are critical. As chiplet architectures and 3D heterogeneous integration (3DHI) become more prevalent, glass interposers incorporating TGVs are receiving increasing attention across the semiconductor industry.
Why Glass?
The substrate material has a direct impact on electrical performance, size, and efficiency of the semiconductor packaging design. Glass offers a unique combination of properties that make it well suited for advanced semiconductor packaging.
Low Dielectric Loss
Glass exhibits very low dielectric loss, allowing high-frequency signals to propagate with minimal attenuation. Lower dielectric loss translates into lower insertion loss and improved overall RF efficiency, making glass particularly attractive for microwave, millimeter-wave, and emerging sub-THz applications.
Excellent Electrical Isolation
Unlike semiconducting substrates, glass is an electrical insulator with extremely high resistivity. This minimizes substrate coupling, leakage currents, and unwanted electromagnetic interactions, improving signal integrity while reducing electrical noise and crosstalk.
Dimensional Stability
Glass provides excellent dimensional stability, a smooth surface for fine-line redistribution layers, and a coefficient of thermal expansion (CTE) that can be tailored for packaging applications. These characteristics support increasingly dense interconnect architectures and advanced manufacturing processes.
How Are Through-Glass Vias Manufactured?
While fabrication methods vary by manufacturer, TGV production generally includes several key steps:
Selection and preparation of the glass substrate
Precision via formation using laser drilling, chemical etching, or other advanced processes
Deposition of conductive seed layers
Copper or other metal metallization to create vertical electrical connections
Redistribution layer (RDL) formation for signal routing
Surface finishing and package integration
Modern manufacturing techniques continue to improve via diameter, aspect ratio, and pitch while supporting wafer- and panel-level production for high-volume manufacturing.
Why TGVs Matter for High-Frequency Design
As frequencies extend into the millimeter-wave range and beyond, substrate losses become increasingly important. Electrical energy lost within the substrate directly impacts insertion loss, signal integrity, and overall system efficiency.
Because glass combines low dielectric loss with excellent electrical isolation, it provides an ideal platform for applications requiring precise impedance control, reduced parasitic effects, and high signal fidelity. These characteristics make TGV-based glass substrates particularly well suited for RF front ends, phased-array antennas, radar systems, and high-speed digital interfaces.
Applications of Through-Glass Vias
TGV technology supports a wide variety of advanced electronic systems.
RF and Wireless Communications
Low-loss glass substrates improve the performance of RF front-end modules, filters, couplers, antennas, and transmission lines used in 5G, satellite communications, and emerging 6G systems.
Artificial Intelligence and High-Performance Computing
Glass interposers enable high-density routing between chiplets while supporting the bandwidth and signal integrity requirements of AI accelerators and advanced computing platforms.
Photonics and Co-Packaged Optics
Glass combines excellent electrical performance with optical transparency, making it well suited for photonic integration and next-generation optical interconnects.
Aerospace, Defense, and Radar
High-frequency radar, electronic warfare, and aerospace systems benefit from the low-loss electrical characteristics and stability of glass-based packaging technologies.
Frequently Asked Questions
How is a Through-Glass Via different from a conventional PCB via?
A TGV is a vertical electrical interconnect formed through a glass substrate, enabling electrical connections between opposite sides of the substrate while preserving the low-loss electrical properties of glass.
Why are glass substrates becoming more important?
As semiconductor packaging evolves toward heterogeneous integration and chiplet-based architectures, glass offers attractive electrical, mechanical, and manufacturing characteristics for advanced interposers and high-frequency applications. These advantages are central to the Technology Platforms framework and its supporting subtopic pages.
Are TGVs only used for RF?
No. Although TGVs are widely used in RF and microwave applications, they are also increasingly adopted in photonics, MEMS, AI computing, advanced sensors, and high-density semiconductor packaging.
Why 3D Glass Solutions?
3D Glass Solutions develops advanced glass-based technologies that enable next-generation semiconductor packaging. Our expertise includes Through-Glass Vias, glass interposers, integrated passive devices, RF packaging, and photonics integration, helping customers design compact, high-performance systems for demanding commercial and defense applications. Explore our Technology Platforms page to see how Integrated Passive Devices (IPD) support these solutions.
As advanced packaging becomes a primary driver of semiconductor innovation, TGV technology will play an increasingly important role in enabling higher bandwidth, improved signal integrity, and greater levels of system integration. By leveraging the unique advantages of glass, 3DGS is helping customers build the next generation of electronic systems.