Warpage analysis of epoxy molded packages using viscoelastic based model

Package warpage during the cooling process just after the molding is one of the critical issues in the manufacture of plastic integrated circuit (IC) packaging. Such warpage depends on the epoxy molding compound characteristics and the dimensional details of the IC package design such as downset and the chip to die-pad area ratio. In this study, the analysis methodology using a viscoelastic based material model is adopted to account the time and temperature dependent behavior of epoxy molding compound. Using such model the effect of compound thickness ratio of the top to bottom side of the package is optimized to reduce the package warpage. Secondly, the effect of the cooling rate on the warpage is also examined in this study.