US 2006/0125119 A1 · B-stageable underfill encapsulant and method for its application

Abstract

A curable underfill encapsulant composition that is applied directly onto semiconductor wafers before the wafers are diced into individual chips. The composition comprises a thermally curable resin system comprising an epoxy resin, a phenol-containing compound such as phenol or phenolic resin, a solvent, an imidazole phosphate salt catalyst, inorganic fillers, fluxing agents, and optionally, wetting agents. Various other additives, such as defoaming agents, adhesion promoters, flow additives and rheology modifiers may also be added as desired. The underfill encapsulant is B-stageable to provide a coating on the wafer that is smooth, non-tacky and will allow the wafer to be cleanly diced into individual chips. A method for producing an electronic package containing the B-stageable material may also utilize an unfilled liquid curable fluxing material on the substrate to which the chip is to be attached.

Claims37

Dependent claims

The B-stageable encapsulant of claim 1 comprising:

a) a thermal curable resin system comprising an admixture of at least one epoxy resin and at least one phenol-containing compound;
b) an imidazole phosphate salt catalyst;
c) at least one solvent;
and
d) at least one inorganic filler;
and
e) at least one fluxing agent,
wherein the encapsulant solidifies at a temperature in the range of about 80° C. to about 160° C. during the B-stage process to produce a smooth, non-tacky surface on a semiconductor wafer or silicon chip and initiates final cure at a temperature greater than about 180° C.

5 more elements

Dependencies are inferred from the claim text.

B-stageable underfill encapsulant and method for its application

Life of this patent

B-stageable underfill encapsulant and method for its application

Life of this patent

Abstract

Claims37