Solder interconnection structure and process for making

A method of increasing the fatigue life of solder interconnections between a semiconductor device and a supporting substrate comprising attaching said device to said substrate by a plurality of solder connections that extend from the supporting substrate to electrodes on said semiconductor device to form a gap between said supporting substrate and said semiconductor device;

• filling said gap with a composition that contains:
• A. binder selected from the group of a cycloaliphatic epoxide, cyanate ester, prepolymer of cyanate ester and mixtures thereof, said binder having a viscosity at room temperature of no greater than about 5,000 centipoise;
• B. filler chosen from the group consisting of aluminum oxide, aluminum nitride, silicon nitride, silicon carbide, beryllium oxide, boron nitride, and diamond powder, said filler having a maximum particle size of 31 microns;
• wherein the amount of A is about 60 to about 25 percent by weight of the total of A and B, and correspondingly the amount of B is about 40 to about 75 percent by weight based upon the amount of A and B;
• and
• curing said composition.