Influence of temperature and humidity on power cycling capability of power modules

Since power electronics becomes more and more important for harsh environments, its power cycling capability under these conditions needs to be known. The goal of this research is to identify how high temperature and humid environments contribute to the damage of power modules during power cycling. Therefore, IGBT modules are tested with power cycling in cold environment, hot, dry environment and hot, humid environment. Additionally, High Humidity High Temperature Reverse Bias testing is done for comparison of different failure mechanisms. Power modules under warm, humid conditions fail significantly earlier than in warm, dry, or even cold, dry environment. This is mainly attributed to two effects. Firstly to the moisture swelling and thermal expansion of the housing material at higher temperatures and humidity which have an influence on the pressure on the thermal interface and secondly the moisture uptake capability of the thermal interface material.