In situ thermal runaway of Si-based press-fit diodes monitored by infrared thermography

Abstract

Overvoltage is one of the main causes that lead to the failure of electronic devices. This makes fundamental to understand the electrical and thermal mechanisms engaged in the process. In this work, the influence of the semiconductor technology on the thermal runaway involved in the dielectric breakdown of commercial press-fit diodes, operating in reverse conditions, has been studied. Infrared thermography has been used to monitor the temperature evolution before, during and after the failure. Schottky and Metal oxide semiconductor devices, based on Si, have been evaluated following this methodology. The current flowing through the diode causes its temperature to rise, which increases the current with a further increase in temperature that triggers the avalanche process. The diode configuration conditions the heating associated with the spark appearing during the breakdown. This process is faster for Schottky diodes than for Metal oxide semiconductors, leading to higher temperatures. Besides, mechanical breaking is observed in the semiconductor due to the stresses generated during the fast heating-cooling processes after the different breakdowns events. The reached temperatures are enough to melt the solder that creates an electrical path, which short-circuits the diodes and leads to their final failure. These differences in the failure behavior must be taken into account to choose the adequate technology in practical applications.