US 2006/0142424 A1 · Foamable underfill encapsulant

Abstract

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.

Claims15

Dependent claims

An expandable thermoplastic or thermosetting underfill encapsulant for use in encapsulating one or more electronic components attached to one or more substrates with a solder that is reflowable at a reflow temperature, the underfill encapsulant consisting essentially of

a) a high molecular weight solid resin system component comprising, a thermoplastic polymer resin or a thermosetting resin and at least one catalyst and optionally at least one phenoxy-containing compound;
b) one or more expandable fillers;
and
c) optionally one or more of group consisting of surfactants, coupling agents, reactive diluents, air release agents, flow additives, adhesion promoters, solvents and mixtures thereof,
wherein the underfill encapsulant expands at a temperature at or above the reflow temperature of the solder.

2 more elements

Dependencies are inferred from the claim text.

Foamable underfill encapsulant

Life of this patent

Foamable underfill encapsulant

Life of this patent

Abstract

Claims15