Breakdown Characteristics of BN Modified Silicone Gel Composite Insulation Materials under High du/dt Voltage

With the development of wide bandgap power semiconductor devices represented by silicon carbide (SiC) to higher voltage levels and faster switching speeds, the reliability of packaging insulation is facing severe challenges. In this paper, the strategy of modifying silicone gel by nano boron nitride (BN) doping is proposed, and the breakdown characteristics of composite insulation materials under high du/dt voltage are studied. The experimental results show that the breakdown voltage of composite insulating materials with different BN doping mass fractions decreases significantly with the increase of voltage rise rate. The doping of BN can effectively improve the high du/dt breakdown voltage of the composite insulating medium, and the modification effect is the most significant when the doping mass fraction of BN is 2%. Further combined with molecular simulation studies, it is found that the change in energy level structure of composite insulating materials under the action of electric field will lead to an increase in the number of carriers, which will accelerate the initiation of avalanche breakdown under high du/dt conditions. The doping of BN changes the charge transport mechanism of the composite material, and enhances the polarization of the molecular chain, thus exhibiting better insulation performance under high du/dt conditions. This study provides important data support and theoretical basis for the development of new high-performance insulation materials for new generation power device packaging.