A Method for Detecting the Initiation of Solder Joint Delamination in a 3-D PCB Assembly of WBG SiC MOSFET

Abstract

This article presents and discusses a method for evaluating the initiation of a solder joint delamination in a 3-D power electronics assembly of SiC MOSFETs integrated into printed circuit board substrate to design a more efficient half bridge. This assembly requires soldering two metallic parts and addresses the integration of active chips with small dimensions compared to the larger heat-sink dimensions to operate only with a convective cooling system. This technological development is part of an effort to assess the robustness of technological choices for a new assembly model of wide bandgap components. However, the conventional methods do not effectively meet the need for detecting the initiation of solder delamination due to the optimized electrothermal assembly design. The method relies on potential difference measurements that exhibit greater sensitivity to detect the onset of solder delamination. Finite element simulations are carried out to assess the method’s sensitivity and discriminating factors, such as geometry and materials involved. Based on the numerical results, the dedicated prototypes of the assembly are developed with controlled delamination rates at the solder joint corners. The results demonstrate that this method is sensitive to detect low delamination rates compared to the traditional method. An improvement of the PCB copper design is made by adding a routing to improve the robustness and the reliability of the method sensitivity.