Selecting Operating Conditions of Power MOSFETs in a Power Cycling Test Based on Thermal Time Constants

This paper presents the results of research on the effect of temperature on damage processes occurring in power MOSFETs. The impact of changes in the activation energy of selected mechanisms initiating the damage process in power MOSFETs during continuous operation on their lifetime is analyzed. Computer analyses and experiments illustrating the effect of transistor switching frequency on time to failure are also conducted. The impact of the relationship between the transistor’s thermal time constants and its switching period on lifetime is assessed. The effect of the transistor’s switching frequency on its junction temperature swing and average value is also assessed. Recommendations for designers of systems using these transistors are formulated to improve their reliability.