Research On Insulation Characteristics Of Silicone Elastomer Resistant To 200? Or Higher Temperature For Packing High Voltage SiC Devices

Silicon carbide(SiC)power devices have become the most potential research object in the field of power devices because of their advantages in high voltage,high temperature and high frequency.Nowadays,SiC MOSFET and SiC SBD and other low-voltage devices have gradually begun to be commercially available,while high-voltage and high-power SiC devices for power grid applications are still in the development stage.the electrical insulation performance has become one of the most critical factors limiting the development of high-voltage SiC power devices,which makes the selection of packaging insulation material particularly important.the packaging insulation material is filled inside the device,which makes each chip of the device have good insulation.at the same time,the dielectric,conductance and discharge characteristics of the package insulation material will greatly affect the internal electric field distribution and the overall insulation performance of the SiC power device under the high temperature and high voltage condition of the SiC power device.The advantage of the SiC device is that at high temperature and high frequency,especially when the frequency above 200?is at the MHz level,because the SiC material has high thermal conductivity and band gap,the heat dissipation of the device is simple,thus greatly reducing the volume of the SiC device.Therefore,the packaging insulation materials of SiC devices need to consider high temperature and MHz high frequency with tolerance of more than 200?.Nowadays,in commercial packaging insulation materials,PI materials and BCB materials will produce voids after curing,the manufacturing process of p-xylene is complex,epoxy resin and silica gel can not meet the temperature requirements of high temperature packaging.Silicone elastomer has become the first choice for SiC device packaging insulation materials because of its high temperature resistance and good electrical insulation.Therefore,this paper focuses on the dielectric conductivity and insulation properties of silicone elastomer.First,the improved preparation method of silicone elastomer is obtained through experimental exploration,and the obtained samples of silicone elastomer are subjected to scanning electron microscopy,infrared spectroscopy,thermogravimetric analysis(20?800?)and thermal stimulation current tests.The key physicochemical properties of silicone elastomer in a wide temperature range are obtained and their effects on the insulating properties of silicone elastomer are analyzed.Secondly,the dielectric properties of organic silicone elastomer are obtained under 10-2?107 Hz,20?280?.Based on the dielectric data of organic silicone elastomer,the dielectric response process of organic silicone elastomer is summarized.The effects of temperature and frequency on the dielectric response process of organic silicone elastomer are analyzed.Thirdly,the modified Cole-Cole model is used to fit the dielectric spectrum data of silicone elastomer,and the fitting method of the improved Cole-Cole model is proposed.The quantitative effect of temperature on the dielectric relaxation process of silicone elastomer is obtained and the mechanism is explained.Finally,the discharge characteristic test platform of silicone elastomer and silicone elastomer under DBC structure are built.The dielectric strength of silicone elastomer at 20?250? is obtained by breakdown test.The effect of temperature on the dielectric strength of silicone elastomer is analyzed by Weibull distribution and its mechanism is explained.Through the discharge test of silicone elastomer under DBC structure,the effect mechanism of temperature on the local discharge of silicone elastomer is found.