Silicon Interposer Packaging for Mixed-Chip Thermal Stability

A silicon interposer substrate is introduced as an intermediary carrier between components of different semiconductor technologies. The interposer has a coefficient of thermal expansion (3.0-4.0 ppm/°C) that matches silicon-based components, while a copper layer (CTE: 17.0 ppm/°C) is integrated to match non-silicon components. This mediator structure eliminates direct thermal expansion mismatches between dissimilar components, preventing cracking and warping under temperature cycling from -65°C to 150°C.

The interposer structure employs a composite design combining silicon substrate with integrated copper layers. The silicon base provides mechanical stability and compatibility with silicon components, while copper traces and vias provide thermal expansion matching for non-silicon components and enhanced thermal conductivity. This composite material approach enables simultaneous compatibility with multiple semiconductor technologies while maintaining structural integrity under extreme temperature conditions.

The silicon interposer serves as a thermal intermediary with high thermal conductivity (1.3-1.5 W/cmK), conducting heat away from active components. The integrated copper layers provide additional thermal pathways with superior thermal conductivity (3.8-4.2 W/cmK), creating a hybrid thermal management system that efficiently evacuates heat from multiple components simultaneously while maintaining their electrical and thermal independence.

The interposer design incorporates controlled thickness variations and copper layer configurations to optimize thermal conductivity parameters. By adjusting the copper layer thickness (0.5-2.0 µm) and density, the structure achieves enhanced heat evacuation capability while maintaining mechanical stability and electrical performance, enabling operation at elevated temperatures up to 150°C without overheating.

The silicon interposer acts as a stable intermediary platform with CTE matching silicon components, providing a thermally stable foundation for high-density interconnections. The copper integrated circuits on the interposer provide additional interconnection pathways with their own CTE characteristics, enabling dense routing patterns without transmitting thermal expansion stresses to the underlying PCB. This mediator structure decouples the high-density interconnection layer from the temperature-sensitive PCB substrate.

The interposer design employs optimized trace and via dimensions, as well as copper layer thickness, to achieve high interconnection density while maintaining thermal expansion compatibility. The structured arrangement of copper traces and vias with controlled pitch and spacing enables dense routing patterns that accommodate multiple components while the overall structure maintains dimensional stability across the -65°C to 150°C operating range, preventing warping even at high interconnection densities.