Semiconductor-based power electronics such as IGBT (insulated-gate bipolar transistor) modules are used in various applications. During their operation, several kilowatts of waste heat are produced in a single module, which must be specifically dissipated in order to guarantee reliable operation. With the trend towards the downsizing of modules and the demand for high power density in the development of new IGBT-modules, there is a need for efficient heat dissipation. Within the scope of a research project the principle of a natural circulation is investigated for the application of cooling power electronics referring to a patent of Fischer, Langebach and Lindenmüller (2017). A metal cover plate, a polycarbonate frame and the IGBT module form the experimental setup. The pool boiling of a low GWP refrigerant at the baseplate of the IGBT module is investigated. With the heat sink of the original base plate surface, a maximum heat flux of 88.6 kW/m² under certain conditions could be dissipated. This value is considerably lower than the results from literature. Additionally, various methods to improve the critical heat flux were conducted and the results are presented.