Plastronic Heat Pipe for the Direct Cooling of Power Electronic Components – CAPREP

The electrification of means of transport requires the development of converters from battery DC voltage to AC voltage for vehicule motorisations. An increase in the performance of these power converters requires power electronic components with very good performance as Gallium Arsenide (GaN) transistors. The consequence is a very high-power density to be dissipated in heat (> 500 W/cm2). The aim of this project is to propose an innovative thermal management of this type of converter by producing in a single piece the device for removing the heat from the transistors to the surrounding environment. An enclosure allowing direct thermal contact between the transistor housings and a liquid, ideally water, forms the evaporator of a heat pipe. The condenser, in the form of hollow fins, completes this unique part made of technical polymer with a thin copper deposit, all produced by plastronic techniques. The heatsink designed in this way eliminates the contact resistances that are prevalent in a conventional assembly. The project is divided into six lots. Lot 1, which is based on previous work between the partners, aims to design, develop and characterize plastronic heat pipes by assembling 3D printed parts using stereolithography. The visualization of the physical phenomena operating within the heat pipe - boiling on the heated surface and condensation in the hollow fins - will allow a better understanding of its operating limits and the implementation of effective methods to push them. Lot 2 explores the possibilities of manufacturing and operating a heat pipe using an industrializable process, requiring the use of a thermoplastic polymer such as polycarbonate. Although, at this stage, the parts will be made by thermoforming and extrusion processes, the shapes chosen will be compatible with an injection moulding process. The demonstration of a solution for dismantling the plastronic device is planned. Lot 3 will look for the optimal thermoplastic polymer with regard to the criteria for choosing the heat pipe, manufacturing constraints and recyclability. In lot 4, three electronic test vehicles will be designed first by conventional manufacturing with classical PCB, then by plastronics. Three developments will be considered: densification of the positioning of the GaN transistors in relation to each other, increase in the chopping frequency, design of a high-power converter (30 kW). Lot 5, dedicated to the manufacture of heat pipes, will supply the other lots. Finally, lot 6 will focus on the Life Cycle Assessment of the alternative device to evaluate the environmental impacts, linked for example to the reduction of mass, and linked to technological indicators such as recyclability. The CaPReP project, coordinated by the Energetic and Thermal center of Lyon (CETHIL), brings together the Power Electronics and Plastronics teams of the AMPERE laboratory, as well as the Institute of Polymer Materials (IMP). The electronic/thermal co-design methodology developed is of great interest, particularly for exploring different ways of improving electronics. Thanks to the collaboration of recognized partners, this multidisciplinary project with a high potential for innovation will enable the "plastronic heat pipe" technology to move from TRL3 to TRL4, thus meeting strong scientific, technological and environmental challenges. The results of the project will be likely to generate contracts with the plastics or electronics industries.