ASIC package lid effects on temperature and lifetime

When considering packaging choices for an ASIC, the target system and its lifetime should be considered. In this study, the overall system thermal conditions are included: heat sink available space, bypass, and air speed as well as chip power map, lid presence and material, and thermal interface materials at die and heat sink. The chip is an ASIC in a ball grid array (BGA) package on a multilayer board. Using numerical modeling to derive a linear response model and then analyzing a large number of samples with the Monte Carlo method, the study concludes that an AlSiC lid is beneficial versus a lidless package when used with a standard forged aluminum heat sink; the mean expected life also increases by 43% with a lid versus no lid. A lid also decreases maximum temperature sensitivity to the heat sink interface material resistivity by an order of magnitude.