Assembly process research of TO package power transistor in aerospace electronic products

In this paper, two processes which are adopted to produce TO packaged power devices are concerned about. The relationship between process factors and equivalent stress and deformation in the joint are studied. Finite element simulation method is adopted to analyze the equivalent stress, strain and deformation in the two processes. Results indicate that both the two processes produce large equivalent stresses, which are over 180MPa. The peak stress locates at the root of contact area of leg and pipe. On the whole, welding stress of process A is larger due to the relatively larger mechanical restraint. To improve the long term reliability for the TO package products, here we put forward a new process, by which smaller equivalent stress is produced.