To solder SMT components, glued to the PCB in a previous process, in a wave soldering system, two solder wave are required in the standard process. The function of the first wave met by the board while traveling towards the exit end of the system, is to wet all pads and leads on the boards where difficult geometries prevail. In the second solder wave the decisive soldering process takes place, where the final formation and the ultimate quality of the solder joint is determined. This second wave is frequently referred to as the "main wave". Modern nozzle designs combine the function of the first and the second wave in one solder wave.