To solder a large number of electronic components on a Printed Circuit Board (PCB), a process termed as wave soldering is utilized. Since waves of melted solder are utilized in this process to solder pins of components on a PCB, it is therefore named as such. Molten solder is held in a tank in which components are placed on the Printed Circuit Board. This stuffed PCB has to travel through a wave of molten solder or we can view it as a waterfall of solder.
Reliable electrical connections are developed when metallic areas on the PCB without solder mask (a solder resist coating on the surface of a PCB) are connected with solder once it is exposed to molten solder. A high quality product which is in fact better one done manually is quickly finished using this technique.
This technique can be utilized for SMT (Surface Mount) components as well as the through-hole ones. In case of SMT, it is important to stick components with any an adhesive material on a PCB before running them through waves of molten solder.