Characterization and modeling the thermo-mechanical cure-dependent properties of epoxy molding compound

Semi-conductor devices are mostly encapsulated by epoxy molding compound (EMC) materials. During encapsulation stresses are generated due to the curing of the molding compound. Moreover, additional stresses will build up during cooling down from molding to ambient temperature caused by the differences in the coefficient of thermal expansion. These residual stresses add up to the stresses generated during mechanical loading and may lead to product failure.The viscoelastic properties of the encapsulation material depend highly on temperature and degree of cure. In this paper the thermo-mechanical properties of an epoxy molding compound with and without filler are investigated both experimentally and theoretically. The cure dependent properties of the EMCs, likewise, the cure kinetics, coefficient of thermal expansion and cure shrinkage were measured using a Differential Scanning Calorimetry (DSC) and a GNOMIX high pressure dilatometer. In addition using a Dynamic Mechanical Analyzer (DMA) the time and temperature dependent storage modulus was measured and mastercurves were constructed.