Improving Thermal Stability and High-Temperature Performance of Silicone Gel Simultaneously Through Low-Concentration Fillers

High-density silicon carbide power electronics proposes high requirements for thermal stability of silicone gel encapsulant. Herein, low-concentration CeO2, AlN, and Al2O3particles are utilized to enhance thermal properties in silicone gel without increasing much viscosity. Different to Al2O3particles, the CeO2and modified AlN could improve thermal stability. Upon increasing the concentration, the decomposition temperature at 95% mass increases first and then decreases in CeO2filled silicone gel. The 0.5wt% CeO2filled silicone gel has the highest decomposition temperature and activation energy of methyl oxidation reaction with only a 10% increase in viscosity, which guarantees excellent thermal stability. It is estimated that the 0.5wt% CeO2filled silicone gel service life at 250°C is increased by approximately 150 times than the undoped silicone gel. Furthermore, thermal expansion coefficient and electrical conductivity at high temperatures are low, and the dielectric constant matching with substrates are great in 0.5wt% CeO2filled silicone gel, which ensures the excellent operation properties at high temperatures. The method improving thermal stability and high-temperature performance simultaneously with low viscosity can aid in high temperature encapsulants fabrication, promoting the development of high-density power electronics.