High-powered thermal gel degradation evaluation on board-level HFCBGA subjected to reliability tests

HFCBGA is a thermally enhanced FCBGA with its heat spreader extending the heat conduction area by connecting itself to the rear side of the silicon die. A thermal interface material plays an important role as a heat conduction path. The thermal performance should not only be checked at time zero, and several reliability tests have to be undertaken to uncover the field conditions faced by end users. A temperature cycling test, highly-accelerated temperature and humidity stress test and multiple reflows are utilized to investigate the thermal resistance of junction to case of a selected thermal gel.