High heat‐resistant (250°C) epoxy resin composites with excellent dielectric properties

Abstract Insulated gate bipolar transistor (IGBT) is the core of electric energy conversion and circuit control, which is widely used in the field of electric vehicles. Higher service temperature, higher power density, and higher operating voltage are the tendency for IGBT in which packing materials have to possess more stable temperature resistance and better insulating properties. In this work, cyanate ester (CE) and polyhedral oligomeric silsesquioxanes (POSS) are introduced into epoxy with various filling ratio to improve the dielectric and thermal properties. The curing process of every system is determined by non‐isothermal differential scanning calorimetry (DSC). N and Si element distribution mappings indicate that there are good compatibility between POSS, CE, and epoxy. The dielectric test shows that the dielectric constant decreases from 4.34 to 2.84 at 1 MHz and from 4.76 to 2.93 at 1 kHz when the filling ratio is 60 wt%. Meanwhile, the DC breakdown strength increases from 172.7 to 286.4 kV/mm. Furthermore, the glass transition temperature ( T g ) increases from 180 to 263°C and the yield of residual carbon increases from 6.2% to 23.7%. A new packing material, which can endure 250°C of operating temperature and has excellent dielectric properties has been synthesized.