Physics-of-failure assessment methodology for power electronic systems

Driven by consumer markets and industrial needs, power electronic systems are operating at higher power densities, in smaller packages and in more exotic environments. As these trends continue, ensuring long-term operation in harsher conditions requires accurate reliability prediction models, most viably obtained through Physics-of-Failure (PoF) methodologies. This paper introduces a PoF-based system-level reliability assessment procedure in which the dominant failure mechanisms are identified for three primary subsystems: the power module, DC-link capacitors and the control circuitry. This report outlines the dominant failure modes and mechanisms for each subsystem and provides examples of how to improve subsystem reliability based upon the described assessment methodology. A case study is also presented in which the solder interconnect reliability of the gate-driver board in a mid-range variable frequency drive (VFD) was assessed.