Reliability research on power MOSFET using coupled electrical-thermal-mechanical analysis

As an integral component of electronic equipments, power MOSFET with its degenerate performance affects the reliability of the whole system. The modeling of power device based on structural geometry, material properties, and boundary conditions can reduce the repetition test and shorten the failure analysis cycle. In this paper, coupled electrical-thermal-mechanical analysis based on finite element model of TO-247 package power MOSFET was performed. First, electrical-thermal simulation was accomplished to obtain the distribution of temperature under power cycling. Then, thermal-mechanical analysis was carried out to calculate the inelastic strain range generated by the thermal stress. Finally, on the basis of simulations above, the fatigue path can be achieved to predict the thermal fatigue life of MOSFET by Coffin-Manson´s law.