Prestressed Method to Improve the Pressure Distribution Uniformity within Press Pack IGBTs

In this paper, a prestressed method is proposed to improve the pressure distribution uniformity within press pack IGBTs (PP IGBTs). The proposed method strengthens the compliance mechanism of plastic strain through a prestress clamping force and therefore obtain a more uniform pressure distribution under rating clamping force. The requirement of machining tolerances could be relaxed through the proposed method, which is generally hard to control in the manufacturing process of PP IGBTs. A simple formula is proposed to fast determine the prestress clamping force under different tolerance cases. The improvement effect of the proposed method is verified by FEM simulation results and experimental results.