Mechanical Foundation
Rigid panels made from high-purity fused silica or borosilicate glass are increasingly used as the central support layer in advanced semiconductor packaging. Glass core substrates provide exceptional dimensional stability and flatness compared to traditional organic laminate cores. This structural layer allows for much finer routing density because the material does not warp or deform under thermal stress.
The high rigidity enables the manufacturing of thinner packaging profiles while supporting multiple high-density interconnect layers. Furthermore, the absence of resin-rich pockets ensures a highly uniform material structure that supports reliable laser drilling and through-hole metallization.
Thermal Match
Matching the coefficient of thermal expansion of the silicon die is a primary advantage of this structural material. It exhibits a thermal expansion coefficient of approximately three to eight parts per million per degree Celsius, which is closer to silicon than organic materials are. This similarity minimizes the thermal-mechanical stress placed on micro-bumps during thermal cycling.
Signal Integrity
The electrical properties of this insulating layer are characterized by very low dielectric loss and high breakdown voltage. It allows for the transmission of high-frequency signals with minimal attenuation, making the technology suitable for high-speed communication processors. Additionally, through-glass vias can be fabricated with high precision, providing short, direct electrical paths between the top and bottom redistribution layers.
Testing these cores involves optical inspection and high-voltage leakage testing to ensure no micro-cracks exist.
