A Multiphysics Modeling and Experimental Analysis of Pressure Contacts in Power Electronics Applications

Abstract

This paper details a modeling and experimental assessment of the packaging process for a silicon carbide Schottky diode using pressure contacts. The work detailed in this paper is original, as it applies a combined electrothermomechanical modeling analysis to this packaging method supported by experimental validation. A key design objective for this packaging process is to identify suitable contact pad materials, heatsinks, and process variables such as clamping force to meet electrical, thermal, and reliability specifications. Molybdenum and aluminum graphite (ALG) have been identified as two suitable materials for the contact pads. Clamping forces ranging from 300 to 500 N and electric current ranging from 10 to 30 A have been investigated in terms of the resulting electrical and thermal contact resistances, temperatures, and stresses induced across the package. The performance of two heatsink designs with heat dissipation rates of 12 893 and 4991 W/ $\text{m}^{2}\text{k}$ has also been investigated. Both the modeling and initial experimental results detailed in this paper show that ALG provides better performance in terms of generating a lower average chip temperature. Both temperature and stress in the diode are predicted as a function of clamping force and load current. This will aid the packaging engineer to identify suitable process parameters to meet junction temperature requirements at different applied load currents.