Package Design And Chip Aging Study Of Press-pack SiC MOSFET Power Electronics

The power device is the core device in the power system.As the power of the power system increases,higher requirements are made on the power level and reliability of power devices.Power device performance is determined by chip performance and packaging performance,so there are two main aspects to improving device performance:using SiC chips and studying new packaging forms.The design and manufacture of SiC MOSFET chips are mature,but their long-term high-temperature working conditions are prone to aging,and the aging mechanism of SiC MOSFET chips at high temperatures is unclear.In terms of packaging,most of the power devices currently use soldered packages.Soldered packages have high thermal resistance,large stray parameters,and are prone to problems such as solder layer delamination and uneven current,which limits the overall voltage level of power device.Press-pack package is potential to improve the power level and reliability of the device,due to the low thermal resistance and the small stray parameters.Besides,there is no bonding wire and solder layer,which avoids solder layer delamination.Despite the significant progress made in the research of press-pack packaging at home and abroad,the problems of uneven current and temperature distribution inside the package have not been effectively resolved.Therefore,in view of the current urgent demand for high-power-level and high-reliability power devices in power systems,the research on the packaging of press-pack SiC MOSFET devices is carried out,focusing on the optimal design of the device package to solve the uniformity current and temperature distribution of the chip inside the device.The aging mechanism of SiC MOSFET chips at high temperature is explored to provide a basis for the development of high-reliability power chips.The main contents of this article are as follows:(1)The demand for high-performance power devices in the power system was analyzed.Based on the research of the domestic and international status of press pack packaging and aging of SiC MOSFET,the study goals and contents of this paper were proposed.(2)The influence of the stray parameters introduced by the package electrode on the electrical performance of the device was studied.(3)The thermo-mechanical coupling model of the press pack device was established,and the influence of the roughness and contact stress of component on the thermal performance of the device was analyzed.On this basis,the requirements of the contact pressure and roughness were put forward.(4)Packages with three type of submodule distributions and two type of cap shapes were designed,and the temperature distribution and current distribution of different packages were analyzed,and the package with uniform current and temperature was obtained.(5)A press pack SiC MOSFET device sample was produced,and the static test of the device was completed.(6)The high temperature electrical stress aging test platform was built,the high temperature electrical stress aging test of SiC MOSFET chip was carried out,and the aging mechanism of SiC MOSFET chip was analyzed.