Patent ID: 7482201

Claim:
A method of making an electrical assembly comprising the steps of: providing an electronic component; providing a substrate, either the electronic component or the substrate having solder bumps and the other having electrical bonding pads; providing a curable underfill bonding composition comprising: polyepoxide resin; curing catalyst; fluxing agent; and surface-treated nanoparticles that are substantially spherical, non-agglomerated, amorphous, and solid, said surface-treated nanoparticles comprising silica, said curable underfill bonding composition having a viscosity of from 1,000 to about 100,000 centipoise at 25° C.; positioning the curable composition between the electronic component and the substrate such that the solder bumps align with the electrical bonding pads to form a curable assembly; and applying heat to the curable assembly to cure the bonding composition.