A Novel Thermal Expansion Matched Heatspreader for Plastic Encapsulation of Silicon Chips

Plastic package thermal resistance reductions of 50% were achieved by leadframe attachment to a novel SiC/graphite composite heatspreader prior to the plastic molding operation of silicon chips. As determined by extended high temperature operational life-tests on special VLSI chips dissipating 0.5 watt, the heatspreader resulted in a 2x improvement in chip lifetime for a wearout mechanism such as electromigration. In addition, Arrhenius extrapolations of instrinsic failure rates to 35°C ambient conditions indicate that an increase in reliability occurs (lower failure rate) of 2x, 4x, and 8x for chips consuming 0.5 watts, 1.0 watts, and 2.0 watts, respectively. Standard environmental lifetests such as biased humidity, autoclave, high temperature storage, and temperature cycling were conducted with favorable results reported.