A Combined Analysis of Moisture Diffusion with Interface Fracture Mechanics on the Interface Delamination in the Plastic IC Packages During Reflow Soldering

Abstract

ABSTRACTThe popcorn cracking phenomenon of plastic IC packages during the reflow soldering was investigated by conducting the stress analysis of heat transfer and moisture diffusion. Vapor pressures at delaminated interfaces between the die pad and EMC(Epoxy molding compound) were calculated and mechanistic parameters such as energy release rate, stress intensity factor and phase angle were derived under various loading conditions; thermal, crack face vapor pressure and mixed loadings. It was shown that thermal loading was the main driving force for crack propagation for small cracks lengths, but vapor pressure loading played more significant role as the crack extended.