Thermal Onboard Detection of Voids in the Solder Layer Between Power Semiconductor and PCB

In this work, a concept for the detection of defects in the solder layer between a power semiconductor and the printed circuit board (PCB) is proposed. Four temperature sensors in the form of discrete diodes are placed adjacent to the semiconductor. Multiple test devices with varying fault patterns in the solder layer are subjected to a power pulse, and the temperature response at the sensors is recorded and evaluated with two different methods. Conclusions about the existence, growth, and position of solder defects are drawn from the measured data. The sensitivity and usability of the concept are discussed.