Impact of the die attach process on power & thermal cycling for a discrete style semiconductor package

This paper investigates the impact of die attach process, including a tilted die, on the power cycling and thermal cycling performance for a discrete style TO220 package. A non-linear material model for die attach solder material is introduced, and an advanced finite element methodology is developed to target the coupled thermal-mechanical problem. For power cycling, a transient thermal analysis is presented, that will show the thermal propagation as the power turned on and off, and the resulting temperature gradients. Then the authors used the cyclic transient temperature loads to apply to the model for the non-linear cycle stress analysis. For thermal cycling, the cycle temperature is directly applied to the model. The parameterized models for different die size and thickness´ are simulated and analyzed. Finally discussion and conclusion regarding this study are presented.