Calculation of Temperature Distribution of Power Si MOSFET with Electro-Thermal Analysis: The Effect of Boundary Condition

Abstract

This paper describes the effect of cooling performance from the bottom surface of power Si MOSFET on thermal properties of power Si MOSFET with electro-thermal analysis. Generally, the bottom surface is assumed to be 350 K as boundary condition in calculations to obtain thermal properties of power Si MOSFET. However, in fact, the bottom temperature is not always constant, and the temperature is depended on the cooling performance. And the bottom temperature is important factor on investigation of a temperature distribution of power Si MOSFET. Therefore, in this study, we investigate the effect of the variation of the cooling performance on the temperature distribution of power Si MOSFET with electro-thermal analysis. The results show, when the heat transfer coefficient is more than 5 × 10⁷ W/(m²·K), the bottom temperature is about 300 K. Further, the variation of the hot spot temperature with respect to the bottom temperature is almost linear.