Foamable underfill encapsulant

摘要

A thermoplastic or thermosetting B-stageable or pre-formed film underfill encapsulant composition that is used in the application of electronic components to substrates. The composition comprises a resin system comprising thermoplastic or thermally curable resin, an expandable microsphere, a solvent, and optionally a catalyst. Various other additives, such as adhesion promoters, flow additives and rheology modifiers may also be added as desired. The underfill encapsulant may be dried or B-staged to provide a coating on the substrate or component that is smooth and non-tacky. In an alternative embodiment, the underfill encapsulant is a pre-formed film. In both embodiments the expandable filler material expands upon the application of higher temperatures to form a closed-cell foam structure in the desired portion of the assembly.