Applied optimization of black oxide flat heat spreader for low-k molded flip chip packages

The most important factor associated with cracking phenomenon during reflow soldering and molding are delamination at the interface of component material of packages. Copper has been widely used as substrate and leadframe as it has good thermal performance. However, Copper surface exposed to environment leading to weak interface bond with polymeric adhesive and encapsulant. Black oxide is a conversion coating applied onto the copper to improve its interfacial adhesion with polymeric adhesives. In this paper we will optimize the parameter of black oxide processing and apply it to flat heat spreader. The experiment results showed that the interfacial-bond strengths between the blackoxide-coated copper heat spreader and epoxy-based molding compound were measured in book mold shear tests.