Multi-chip-module substrate decreasing signal delay and improving thermal conductivity

An MCM (multi-chip-module) substrate which has less parasitic capacitance and less thermal stress displacement than the conventional type of substrate has been developed. A low- epsilon fluorocarbon resin for interlayer insulator underneath the multi-wiring layers in the substrate on which LSI chips should be mounted was used. The remaining portion of the substrate was filled with insulating material which has high thermal conductivity and low expansion coefficient, e.g., polyimide resin or silicone resin mixed with boron nitride, alumina, silicon carbide, and/or silica. As a result, one could improve the signal delay and characteristic impedance by 30 approximately 40%, decrease the thermal stress displacement 0.22 approximately 0.39 times, and improve the thermal conductivity 1.5 approximately 1.8 times, compared with existing technology using polyimide only.<>