No-flow underfill material having low coefficient of thermal expansion and good solder ball fluxing performance

摘要

A no-flow underfill composition comprising an epoxy resin in combination with epoxy hardener and optional reagents and a filler of a functionalized colloidal silica having a particle size ranging from about 1 nm to about 250 nm. The colloidal silica is functionalized with at least one organoalkoxysilane functionalization agent and subsequently functionalized with at least one capping agent. The epoxy hardener includes anhydride curing agents. The optional reagents include cure catalyst and hydroxyl-containing monomer. The adhesion promoters, flame retardants and defoaming agents may also be added to the composition. Further embodiments of the present disclosure include packaged solid state devices comprising the underfill compositions.