Articles » Glass vs. Silicon: Pros & Cons of Glass RF Interposers

Glass vs. Silicon: Pros & Cons of Glass RF Interposers

Published on February 20, 2026

6g glass interposer silicon interposer glass vs silicon

Introduction : Wireless technologies are advancing and we are moving toward 6G and sub-THz (frequencies above 100 GHz) domain. Traditional organic materials are becoming too noisy and lossy for high frequency signals. To solve this issues, interposers have been developed to bridge layers that connect high performance chips to circuit board.

For years, Silicon has been the gold standard for high density packaging. However, a new challenger is emerging that is Glass. Let us compare the two materials and look at the pros and cons of moving to a glass based architecture.

Comparison between Glass and Silicon

While Silicon is a semiconductor that can be engineered to be high resistivity for RF purposes, Glass is a natural insulator. The following table provides major differences between them based on how they handle high frequency signals.

FeatureSilicon InterposersGlass Interposers
RF LossHigh (without expensive additives)Exceptionally Low
ManufacturingWafer based (Mature)Panel based (Scaling)
Surface SmoothnessVery HighUltra-High (<10 nm roughness)
Thermal ConductivityHigh (Good for cooling)Low (Thermal Insulator)
Cost ScalingExpensive at large sizesCost effective at large panel sizes

Pros of Glass Interposers

Following are some of the benefits or advantages of glass interposers.

  1. It offers exceptional RF efficiency. At frequencies above 100 GHz, the loss tangent of a material becomes critical. Glass offers a wide dielectric range and near zero electrical leakage. This allows signals to travel through the packaging with minimal degradation, which is vital for the power sensitive antennas used in 6G.
  2. It offers dimensional stability and Coefficient of Thermal Expansion (CTE) tunability. This helps glass to perfectly match CTE with silicon dies it carries. This prevents warping and ensures the integrity of thousands of tiny vertical connections.
  3. Glass substrates can achieve a surface roughness of less than 10nm, providing a “mirror smooth” path for high frequency electricity.
  4. Unlike organic laminates, glass does not absorb water. This means the electrical performance of a glass based RF system won’t change whether it’s operating in a dry desert or a humid tropical environment.

Cons or challenges of Glass Interposers

  1. In silicon, we use “TSVs” (Through Silicon Vias) - tiny holes etched with chemicals. In glass, we use TGVs. Drilling millions of microscopic holes in a brittle sheet of glass without causing micro-cracks is a massive engineering challenge.
  2. It offers poor thermal conductivity. Silicon is a relatively good conductor of heat, helping pull warmth away from hot chips. Glass, however, is a thermal insulator. If you are running high power GaN (Gallium Nitride) amplifiers on a glass interposer, you have to be much more creative with your cooling solutions to prevent the device from overheating.
  3. Ecosystem maturity is also a concern. The semiconductor industry has spent 50 years perfecting the silicon wafer supply chain. Moving to large format glass panels require new equipment, new metallization processes and new handling standards.

Conclusion

  • Use Silicon if: You are building ultra-dense, logic heavy systems (like AI accelerators) where thermal management and mature high density routing are the top priorities.
  • Use Glass if: You are designing for 6G, mmWave Satcom or high end Radar. If your goal is to minimize signal loss at 100 GHz and above and you need a stable, moisture proof platform that can scale to large antenna arrays, glass option can be preferred.