Thermal shock resistance of flat plastic integrated circuit packages

Studies were made on the thermal shock resistance of flat packages (FP) to determine the correlations among thermal stress, polymer strength and median life. FP from a composite of different epoxy molding compounds were used to test thermal shock resistance. Results of the study indicated that when glass transition temperature, coefficient of linear expansion and modulus of elasticity values decrease, the median life to crack initiation increases. Median life depends on the cross-sectional areas of the FP and the lead frame, and is directly proportional to polymer strength.