Automatic Transient Thermal Impedance Tester for Quality Inspection of Soldered and Sintered Power Electronic Devices on Panel and Tile Level

Transient thermal analysis (TTA) is an established method to evaluate thermal integrity of interconnects in power semiconductor modules. In this paper the suitability to detect bad interconnects is investigated. In especially for sintered interconnects TTA has potential advantages compared to standard methods like X-Ray where voids but no bad wetted contact can be observed or SAM (scanning acoustic microscopy) where the device has to be immerged in water. An automated TTA equipment prototype was developed to enable fast automatic mass testing for soldered and sintered MOSFETs. The automatic TTA tester was benchmarked to X-Ray, SAM and shear strength tests on sintered MOSFETs. Thereby different packages, surface metallization and sinter profiles were tested. The measurements showed that the evaluation of X-Ray and SAM data is strongly limited for sintered interconnects. With TTA and the destructive shear strength test, small variation in quality were detectable.