Investigation on Formation and Evolution Behavior of Short-Circuit Path in Press-Pack IGBT Modules

The formation and the evolution behavior of short-circuit paths in press-pack IGBT (PP-IGBT) are investigated by combining test and finite element (FE) simulation. First, the large current impact test is conducted, and the characteristic parameters in the limited vision zone from the thermal runaway to the short-circuit path formation are obtained. The FE model of a short-circuit path with time-varying resistance is proposed to simulate the formation of a short-circuit path. Second, the durability test is conducted on a failed 3.3-kV/50-A submodule, and the FE model of the short-circuit path with the length-varying is proposed to simulate the evolution behavior in the submodule. Third, the durability test is conducted on a 3.3-kV/1.5-kA multichip module with a preembedded failed submodule. The FE model of a short-circuit path with failed submodule numbers-varying is proposed to simulate the evolution behavior in a multichip module. The results indicate that Al-Si fusion is an important reason for the short-circuit path formation. In the submodule, the short-circuit path extends around the edge of the active area. In the multichip module, the short-circuit path rapidly spreads from the central submodule to the edge submodule, then expands along the edge, exhibiting a thermal infection pattern, and finally forms a relatively stable short-circuit path.