Simulating package behavior under power dissipation using uniform thermal loading

The thermomechanical behavior of electronic packages under power dissipatio n is simulated using uniform thermal loading. Two packages are studied, a l arge periphery leaded plastic quad flat pack (PQFP) package and a more comp act plastic ball grid array (PBGA) package, both mounted on a printed circu it board (PCB), Experimentally verified linear elastic finite element model s are used to find the displacements at the predicted failure location duri ng power dissipation, and then during uniform thermal loading. The results for the two cases are then analyzed to find correlations between power diss ipation levels and equivalent heating temperatures. One use of the results could be to replace power cycling fatigue tests with thermal cycling tests. For the packages studied, the results revealed that very little uniform hea ting is required to simulate the thermomechanical effects at the failure lo cation resulting from power dissipation. Due to the prestrained state of th e packages at room temperature, power dissipation decreases the expansion m ismatch while increasing the thermal mismatch between package and PCB.