Wave soldering, also known as flow soldering, is normally performed in a protective gas atmosphere since the use of nitrogen offers an opportunity to reduce solder defects. While the wave soldering process can be designed to be more secure, it has distinct technological limitations.
Selective soldering is also a form of flow soldering and offers the only possible soldering method where through-hole components must be soldered on both sides of a two-sided printed circuit board assembly.
Although wave soldering can be used successfully for large unit volume production, since it is a form of mass soldering it has several disadvantages including:
Because of these disadvantages the overall operating costs for a typical wave soldering machine can be as high as five times greater when compared to a selective soldering machine.
Selective soldering is a variant of wave soldering used mainly for soldering printed circuit boards that are assembled partly or even entirely with through-hole components.
Selective soldering in most cases consists of three stages; 1) fluxing or the application of liquid flux, 2) preheating or the printed circuit board assembly, and 3) soldering with a site-specific solder nozzle.
Due to its inherent process flexibility, selective soldering can be used successfully for soldering a wide range of printed circuit board assemblies and has several distinct advantages including:
Process optimization can be obtained securely and quickly