SOLDERING DETERIORATION OF EPOXY-MOLDED IC PACKAGES AFTER MOISTURE ABSORPTION

Molding compounds for surface-mount devices were studied by using vari ous kinds of epoxy resins in a practical model compound with phenol re sins as curing agents. The physical properties of the cured compounds were studied at 215-degrees-C to simulate the condition that they enco unter during the soldering process that can relate to package cracks. The compounds that have low modulus at soldering temperature, low equi librium water concentration, and good adhesion toward the die pad deve loped few cracks after soldering. The compounds from difunctional epox y resins showed good durability, resisting this phenomenon. (C) 1994 J ohn Wiley & Sons, Inc.