Indium Blog

Flip Chip Epoxy Flux

Just in case you haven’t heard of epoxy flux yet, let me fill you in.

Epoxy flux is what I call a “super no-clean” flux. A no-clean flux is designed to entrap unused activator in a semi-solid residue. With epoxy flux, that residue is an actual epoxy – just like underfill. The advantage of this is the compatibility with underfill. Epoxy flux isn’t supposed to be used alone, it is used in place of a normal flip chip flux. After soldering with epoxy flux, you still encapsulate the flip chip with capillary underfill as usual. The capillary underfill can attach to the epoxy flux residue much better because of the similar chemical nature of both materials.

Authored by previous Indium Application Manager Jim Hisert