In a previous paper the authors had presented a novel, electrically insulating heatsink concept for power semicon-ductor switches (IGBT) based on natural circulation (Hu, et al., 2021). The working principle of the heatsink relies on pool boiling on the bottom of a vapor chamber and film condensation on the condenser above. An insulating refrigerant is used. The principle of this heatsink is introduced in a patent by Fischer, Langebach and Lindenmüller (Germany. Patent No. DE102017215952B3, 2017). In the mentioned paper (Hu, et al., 2021) the authors com-pared the direct contact between the IGBT’s bottom plate and the refrigerant with the utilization of a copper inter-face plate with a defined surface structure with open microgrooves. Other methods for increasing the critical heat flux (CHF) in the chamber, such as silicon pin-fins or free copper particles, were discussed as well.

In this paper the authors present an extension to the research done before. Since the direct contact between the power semiconductor module and the refrigerant has shown crucial drawbacks in CHF and thus overall cooling performance, this work focusses on the use of metal interface plates between the IGBT and the refrigerant. The influence of material choice and surface texture are discussed and experimentally verified. Additionally, a compari-son between two different refrigerants and their effect on cooling performance and CHF is shown. As a conclusion the use of sandblasted interface plates is recommended. Copper should be used, aluminum can be used, but with lower thermal performance.