High-power-used thermal gel degradation Evaluation on board-level HFCBGA subjected to reliability tests

HFCBGA is a thermally enhanced FCBGA with its heat spreader extending 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 be checked not only at time zero, several types of reliability tests have to be examined to cover the field condition faced by end user. Temperature cycling test, highly-accelerated temperature and humidity stress test and multiple reflows are chosen for investigating thermal resistance of junction to case of a selected thermal gel.