Solder Defect Detection for Power Semiconductors by Adjacent Temperature Monitors

In this work a concept for detection of defects in the solder layer between a power semiconductor and the printed circuit board is proposed. Temperature sensors in form of discrete diodes are placed adjacent to the semiconductor. Three different test arrangements are investigated of which two possess a predefined fault within the solder layer. To experimentally validate the concept, the tested device is subjected to a power dissipation pulse and the temperature response at the sensors is recorded and evaluated. Conclusions about the existence and position of solder defects are drawn from the measured data. The sensitivity and usability of this concept is discussed. Furthermore, a 3D thermal simulation is provided to explain the measurement.