Abstract
Roughening of metal surfaces frequently enhances the adhesion strength of polymers to metals by mechanical interlocking. When a failure occurs in a polymer/roughened metal system, the failure is prone to be cohesive within the polymer. In a previous work, an adhesion study on a polymer (epoxy molding compound, EMC)/roughened metal (brown-oxide-coated copper-based leadframe) system was carried out, and the correlation between the failure path and adhesion strength was investigated. In the present work, an attempt to explain why such failure paths occurred was made under the assumption that microvoids were formed in the EMC, as well as near the roots of the CuO needles during the compression-molding process. A simple adhesion model developed from the theory of fiber reinforcement of composite materials was introduced to explain the adhesion behavior and thereby explain the formation of failure paths. It is believed that the adhesion model developed in the present work can be used to explain the adhesion behavior of other similar polymer/roughened metal systems.