Studies on the reliability of power packages based on strength and fracture criteria

Thermal cycling induced failure in power packages has been studied comparing thermal cycling (TC) with thermal shock (TS) tests by thermo-mechanical analyses. The major question for the time reduction is if the failure mechanism changes and if it depends on loading type and duration. These questions were addressed by theoretical analyses including coupled transient thermal–mechanical analyses and interface fracture mechanics applying the cohesive zone approach. By the latter, critical states for delamination failures could be derived. Finally, critical interface fracture parameters of the package were compared with results from the button shear test.