Development of biphenyl epoxy type molding compound for surface mount devices

We developed and commercialized the biphenyl-type epoxy molding compound at the first time in 1989, which was suitable for surface mount devices. The biphenyl-type epoxy molding compound with low crosslinking density showed h igher fracture toughness at high temperature than conventional cresol novol ac-type epoxy molding compound. Furthermore, water absorption was reduced b y increasing the silica content through the addition of small amount of mic ro spherical silica that gave good fluidity to the molding compound. As a r esult, the biphenyl-type epoxy molding compound made a significant improvem ent on resistance against cracks during re-flow soldering process. We also developed and commercialized the halogen-free flame retardant epoxy molding compound in 1995. By decreasing content of flammable epoxy matrix resin in the compound and increasing aromatic group content in the epoxy ma trix resin, the flame resistance of the epoxy molding compound without eith er halogenated flame retardant or antimony compound successfully passed the level of UL94, V-0. It also possessed excellent reliability, such as heat resistance, humidity resistance and re-flow soldering resistance, due to it s low impurity and low water absorption.