A defined quantity of an inert fluid (usually perfluorpolyether) is vaporized during reflow soldering in the process chamber, which is hermetically sealed by means of a bulkhead. The vapor allows for extremely effective heat transfer to the PCBs due to the release of heat during condensation, and the temperature of the medium remains constant. In addition to this, the medium’s boiling point limits the maximum soldering temperature so that the PCBs cannot be damaged due to overheating. This, as well as the ability to control the volume of injected liquid and intermediate exhaust of the vapor, also makes it possible to precisely adjust the temperature/ reflow profile of the PCB. Flawlessly reproducible soldering results are thus guaranteed, which minimizes scrap rates.