Clamping Force Effects in Press-Pack FRD Chips: Single Pulse Surge Withstand Capability Analysis

Clamping force is a crucial factor affecting the robustness of press-pack fast recovery diode modules (PP-FRDs). However, there is currently a lack of understanding regarding the influence of clamping force on the surge withstand capacity limit of PP-FRDs. Therefore, this paper begins by experimentally exploring the effects of clamping force deviation and magnitude on the surge withstand limits of PP-FRD. The findings reveal that the degree of clamping force deviation is the predominant factor. Subsequently, the failure mechanisms of PP-FRD under surge conditions, along with its electrical, thermal, and mechanical behaviors, are examined by combining the surge failure morphology and the electro-thermal-mechanical coupled finite element model (FEM). Furthermore, a method is proposed to assess the surge limit of PP-FRD by quantifying the degree of clamping force non-uniformity using Fuji pressure paper. In addition, the mechanism of chip surge failure was also analyzed based on physical detection. Lastly, the influence of clamping force on the surge withstand capability of parallel PP-FRDs was experimentally examined. The results demonstrate that chips with uneven clamping force hinder the overall surge limit of the parallel dual PP-FRDs. The influence of imbalanced current sharing becomes significantly more evident as the number of parallel PP-FRDs increases to four.