Analysis on thermal simulation of MOSFET based on voids under working conditions

In automotive electronic water pumps, MOSFET is used as power conversion devices to drive water pump motors, however, the high temperature of the engine will cause the electronic water pump MOSFET to overheat and fail. In order to effectively reduce the overheating failure of MOSFET, a thermal simulation model of printed circuit board MOSFET for automotive electronic water pump controllers was established using FLUENT software. The temperature rise characteristics of MOSFET with different void rates under single and multi-void SMT states were analyzed. The analysis results indicate that the thermal resistance of MOSFET in printed circuit boards increases with the increase of void fraction, and the simulation results are verified through experiments, which are consistent with the simulation results. At the same time, when the void ratio is greater than 10 %, the heat dissipation effect of a single void is more pronounced than that of a void. The thermal analysis of printed circuit board MOSFET provides support for effectively controlling MOSFET temperature rise and reducing MOSFET thermal failure. • A CFD simulation model for MOSFET in engine water pump controllers was established to simulate and test its operation and temperature changes. The study investigated how voiding rate affects MOSFET's thermal resistance and temperature rise, noting that void forms also influence these factors. • Solder voiding directly impacts MOSFET's working temperature, increasing local temperatures in both single- and multi-void conditions. Notably, single-voids have a greater influence on temperature rise. • As voiding rate increases, MOSFET's thermal resistance rises, with a significant jump when single void rates exceed 10%, highlighting the substantial impact of large single voids. • Both single and multiple voiding rates significantly affect MOSFET's operating temperature, emphasizing the importance of avoiding large concentrated voids during PCB assembly to ensure normal operation.