The solder wave is at the heart of wave soldering and selective soldering systems. The wave is formed by a nozzle, which is continuously supplied by a pump with fresh solder. The solder is made to overflow on the nozzle, and this overflowing solder constitutes the wave. The wave wets the pads and leads on the assembly; depending on the process it wets either the full area (wave soldering) or only partially (selective soldering). For wave soldering systems, a number of different wave geometries have been developed and brought to the market. Yet predictions on the quality of the soldering results attainable these different nozzles are virtually impossible, as the quality of the result is largely dependent on the layout of the board. Generalizations cannot be made. Geometries such as the Lambda nozzle, or nozzles with similar shape, deliver acceptable to good results.