Field Grading Composites Tailored by Electrophoresis—Part 3: Application to Power Electronics Modules Encapsulation
Sombel Diaham, Zarel Valdez‐Nava, Trong Trung Le, Louis Lévêque, Lionel Laudebat, Thierry Lebey
Abstract
A series of three articles presents an innovative way to build advanced functionally graded materials (FGM) based on polymer/ceramic (epoxy/SrTiO3) composites tailored by electrophoresis for field grading in power electronics. In Part 3, this method is applied in the context of power modules for DBC substrate encapsulation. An evaluation of the FGM performances is reported based on electrostatic simulations and breakdown voltage measurements on encapsulated DBC substrates. The results show a significant mitigation of the electric fringe field at the triple point while breakdown is largely increased by a factor 2 for FGM composites compared to neat epoxy. The process enables the use of electric field reinforcements of HV electrical systems (e.g. tips coming from the design), and thus potential weak points, to locally `self-heal' them in-situ. Such an electrophoresis process used to build FGM composites paves the way for the next generation of functionalized polymer composites used in high voltage power applications for improving the electrical aging of insulating materials and power system reliability.