In Situ Contact Pressure Monitoring of Press Pack Power Module Using FBG Sensors

Abstract

For press pack power semiconductor modules, the contact pressure is a key parameter to monitor their operating condition and health status. Direct internal measurement using conventional sensors has been difficult due to the restricted space and strong electromagnetic interference (EMI). This paper proposes a method by using optical fiber Bragg grating (FBG) sensors. To facilitate the FBG measurement, the contact force needs to be converted to an appropriate tensile strain in a tailored spring stack structure within the modified power module, and the in-situ contact pressure is then measured using integrated FBG sensors to detect this tensile strain. The thermal influence on the strain measurement is eliminated by temperature compensation. The sensitivity and accuracy of the proposed method are verified in experiments.