Thermal Design And Optimization Of Double-Sided Cooling Power Device Package

Power devices,as the core components of power electronic systems,are widely used in high-speed railroads,new energy vehicles and other fields.Driven by the goals of carbon neutrality and carbon emissions peak,power devices are developing rapidly towards high power and miniaturization.However,against the background of increasing package density and power consumption of power devices,the heat dissipation requirements of power devices are also increasing,as the increasing heat flux seriously affects their electrical performance and lifetime.It is a research hotspot in the industry for effective thermal management of power devices through its package thermal design.To improve the heat dissipation of power devices,a double-sided cooling power device(DCPD)packaging is designed,which is cooled by a finned heat sink and a microchannel embedded in the PCB.The results are shown below:(1)Based on the thermal conduction path and equivalent thermal resistance network,a double-sided cooling power device packaging is designed with reference to the circuit and internal structure of an intelligent power module.The packaging process of DCPD is to add laser drilling and copper plating based on the QFN process,and its feasibility is verified by experiments.Meanwhile,the thermal resistance of different substrate samples is tested by a T3 Ster thermal transient tester to determine the mechanism of substrate material influence on heat dissipation.The results show that the higher the thermal conductivity of the substrate material,the lower the thermal resistance and the lower the sample temperature.(2)The thermal-mechanical coupling simulation analyzes the plastic encapsulated intelligent power module and DCPD,and explores the effects of substrate,solder,copper-clad rate of PCB and copper plating on the thermal-mechanical characteristics of DCPD.The simulation results show that the maximum temperature,thermal resistance and maximum equivalent stress of DCPD are reduced by 38.56℃,94.76% and 18.55%respectively,compared with the former.In addition,the copper-clad rate of PCB and copper plating are also important for DCPD heat dissipation.As the thermal conductivity of the substrate and solder increases,the chip junction temperature and thermal resistance become lower.Furthermore,the area and thickness of the substrate are negatively correlated with the maximum equivalent stress.When the thickness of solder increases,the maximum equivalent stress of solder and chip increases overall.The greater the void ratio of solder,the greater the thermal stress of substrate,solder and chip.(3)To achieve better heat dissipation,the heat sink parameters and copper plating structure are optimized by the orthogonal test method to determine the optimal structure of DCPD.Finally,the thermal characteristics of the optimized DCPD are analyzed and the simulation results are as follows.When the total power is 30 W,the maximum chip temperature and thermal resistance of the optimized DCPD are 47.37°C and 2.60°C/W.When the chip junction temperature is 120°C,the power consumption and the maximum equivalent stress of the chip of DCPD is about 26 times and about 50% of that of the plastic encapsulated intelligent power module.In this paper,the research results can provide a practical package thermal design scheme for obtaining efficient heat dissipation of power devices and an optimization method for double-sided cooling.