International Business Machines Corporation
Flip chip packaging rework

Abstract:

Rework and recovery processes generally include application of liquid metal etchant compositions to selectively remove one layer at a time of a solder layer and underball metallurgy multilayer stack including a titanium-based adhesion layer, a copper seed layer, a plated copper conductor layer, and a nickel-based barrier layer. The rework and recovery process can be applied to the dies, wafers, and/or substrate.