Predictive model for adhesion loss of molding compounds from exposure to humid environments

While absorbed moisture poses a significant threat to the reliability of microelectronic assemblies, the role of moisture to the constitutive damage behavior of interfacial adhesion is not clear. There currently exists a lag in fundamental empirical data depicting the loss in interfacial adhesion as a function of moisture concentration. Given this lag in experimental data, even less effort has been spent developing predictive models that account for the effect of moisture on interfacial adhesion. This paper presents a systematic study conducted to better understand the fundamental science of moisture-induced degradation of interfacial adhesion. It is comprised of both experimental and modeling components of analysis. The experimental portion of this work characterizes the intrinsic interfacial adhesion loss from moisture and identifies the major energy dissipation mechanisms involved in the debonding process for an epoxy-metal bond. The analytical model is based on absorption theory and uses fracture mechanics to predict the loss in adhesion as a function of moisture content. Good agreement is obtained when comparing model predictions to experimental data