Gideon Analytical Laboratories performed failure analysis on several IXYS IGBT IXGH32N60B transistors, encased in TO-247 packages. These transistors are 60 amp 600V 2.3 Rds 200W. The concern was that the devices were not functioning as 600V but topped out at 480V in the application.
Displayed in the picture above is a defect near the guard ring. Further analysis revealed there are several metal posts contacting more than likely underlying diffusion for voltage termination. These metal posts seem to be the area of vulnerability. There is a hole in the passivation, which has allowed moisture to ingress the metal. Because of the erratic behavior of the initial BVces measurements (baked out to eliminate moisture), the consistent failure mode of lower BVces associated with the termination structure, and the passivation integrity test demonstrating termination vulnerability leads one to conclude that the problem is an ingress moisture related issue, not an application issue. Good parts had nothing wrong with the passivation and functioned in the application with normal BVces.
Failure analysis performed by Gideon Analytical Laboratories can be a tremendously beneficial tool for a variety of companies in the electronics industry. If your company is having a process, component, design, manufacturing, or assembly failures, call us.