An Electric Field Assisted Dielectric Functional Gradient Layer for Insulated Gate Bipolar Transistor Packaging

Abstract

Wide-band gap insulated gate bipolar transistors (IGBTs) have attracted much attention due to their large energy gap and high breakdown electric field. However, the increased voltage levels of IGBT lead to higher electric field strength that conventional encapsulation materials cannot withstand. In this study, a finite element method is used to simulate the electric field distribution of the IGBT packaging. Based on the structure with rounded electrodes and protruding substrate, an electric field-assisted BaTiO3-Resin composite is proposed as an encapsulant to reduce the electric field strength within the IGBT. The effect of the dielectric functional gradient layer on reducing the maximum electric field strength was analyzed by simulation, and the feasibility of the electric field-assisted method was verified by experiment. Compared to the initial model, the maximum electric field strength of the optimal model reduces from 258 kV/mm to 39.9 kV/mm. The optimal structure with a dielectric layer reduces the electric field inhomogeneity factor from 9.0 to 1.5. Scanning electron microscope images indicate the feasibility of fabricating BaTiO3-Resin composites with electric field-assisted assembly. The integrated structure and material optimization strategy for the IGBT packaging with a dielectric functional gradient layer have promising applications for solid insulation.