High Cycle Fatigue Testing of Silicon IGBT Devices Under Application-Close Conditions

To speed up the testing time in a power cycling test, normally high-acceleration factors induced by high temperature swings are applied. With a classical Coffin–Manson lifetime approach, the induced fatigue can be modeled. This work uses test conditions at the transition between the elastic and plastic deformation zones. Testing the high cycle fatigue zone requires evolved equipment, so active power cycling with switching losses is implemented. It was found that for high junction temperatures (T_vj,max = 150 °C), a transition between the plastic and the elastic zones could not be detected down to ΔT = 18 K. However, for reduced junction temperatures (T_vj,max = 115 °C), the start of the elastic zone was found at around ΔT < 29 K. The main failure mechanism was found to be chip solder fatigue in the center of the solder layer. The experimental data are transferred into a 3-D simulation environment to further investigate the failure mode. With the findings, a lifetime model is described and applied, which predicts, depending on conditions, lifetime benefits up to 268% compared with a standard lifetime approach.