Liquid Cooled And Packaging Reliability Study Of IGBT For EV

In recent years, EV(Electrical Vehicle) has achieved a rapid development because of its environmental and energy saving. IGBT(Insulated Gate Bipolar Transistor) is an important and essential component of EV. It plays a role of level switch, AC-DC conversion, battery charging and system control. But it has a harsh working environment, large density of heat dissipation and a complicated packaging structure. Poor heat dissipation lead to temperature increase and will cause performance degradation even burned up. It will cause thermal stress when temperature changes of packaging model. Excessive and in homogeneitythermal stress will cause crack of chip and ceramic layer, lead to fatigue failure of packaging model. Liquid cooling and thermal stress of IGBT module are analyzed in detail.It provides a theory supporting by analyzing heat dissipation path and thermal resistance for improving heat-dissipating method. A convenient, accurate and economical comparing platform is proposed for comparing different types of plate-pin fin. Eight different plate-pin fin are compared through the platform, it presented that the 60° angle diamond shape staggered plate-pin fin performs better. A method of uniform design and regression analysis are used to optimize the parameters of plate-pin fin. The optimized 60° angle diamond shape staggered plate-pin fin is used in the Infineon Hybridpack2 heat dissipation model and obtain satisfactory effect.The study of aluminum coating on chip and aligned packaging method presented that the aluminum coating can significantly raise thermal stress on chip up to 25.3% and the thermal stress can be reduced at either end of the solder upon base plate. The biggest thermal stress appears in the ceramic of DBC plate.In order to improve the harsh environment of thermal stress, thermal stress buffer and slotting of base plate are proposed. Thickness, material type, three layer grade buffer and slotting of base plate are analyzed in detail. The results presented that thermal stress buffer has a significant effect in improving the thermal stress; With increases in the thickness of buffer, thermal stress has little rise; Three layer grade buffer can reduce stress of chip and the stress gradient of packaging materials. Slotting on base plate can reduce thermal stress of model but not related to the number of slotting.