Recent advances in electric motors and associated power electronics have led to a significant increase in power density requirements. This increase in power density means smaller heat exchange surfaces, which amplifies the challenges associated with dissipating the heat generated by power electronics components during operation. In fact, the lack of adequate heat dissipation causes electronic components to overheat, impacting their performance, durability, and reliability. Other issues related to cost, repairability, and thermomechanical constraints call into question traditional ceramic-based insulating thermal interfaces. It is therefore imperative to develop a new generation of heat-dissipating materials that take the system environment into account.
The objective of this thesis is to replace the ceramic substrate in power module systems, whose main role is to act as the system's dielectric layer, with a thermally conductive organic matrix composite. The current substrate has well-known limitations (fragility, poor interface, cycling limit, cost). The organic substrate must have the highest possible thermal conductivity (>3 W/m.k) in order to dissipate the heat emitted properly, while also being electrically insulating with a breakdown voltage of approximately 3kV/mm. It must also have a coefficient of thermal expansion (CTE) compatible with that of copper in order to eliminate delamination phenomena during the cycling undergone by the device during its lifetime. The innovation of the doctoral student's work will lie in the use of highly thermally conductive (nano)fillers that will be electrically insulated (insulating coating) and can be oriented in a polymer resin under external stimulus.

The development of the electrical insulating shell on the thermally conductive core will be carried out using the sol-gel method. The synthesis will be controlled and optimized in order to correlate the homogeneity and thickness of the coating with the dielectric and thermal performance of the (nano)composite. The charge/matrix interface (a potential source of phonon diffraction) will also be studied. A second part will focus on grafting magnetic nanoparticles (MNPs) onto thermally conductive (nano)fillers. Commercial MNPs will be evaluated (depending on requirements, grades synthesized in the laboratory may also be evaluated). The (nano)composites must have rheology compatible with pressing and/or injection processes.