Mechanical properties of IGBT module under Temperature Shock Test considering residual stress

Temperature Shock Test (TST) is a basic test for Insulated Gate Bipolar Transistor (IGBT) modules, which can effectively reveal the problems existing in device packaging. In engineering, the IGBT module baseplate will be prebent before packaging, and the baseplate becomes flat after reflow soldering. Considering the prebend of the baseplate, the residual stress and deformation of the IGBT module after reflow soldering were calculated based on finite element method. Considering the residual stress after reflow soldering, the stress and strain characteristics of IGBT modules under different TST conditions were studied, and the effects of different holding times on the equivalent stress and deformation of IGBT modules were analyzed. The calculation results show that after reflow soldering, the maximum residual stress of the solder layer is 47.8 MPa, at which time the prewarpage of the baseplate changes from 0.6 mm to 0.026 mm, therefore the baseplate becomes basically flat. Under temperature cycles, the deformation of the baseplate gradually increases. In the same time, when the holding time is 30 minutes, the deformation of the baseplate is relatively larger due to the number of cycles.