wavesoldering

Wavesoldering is a mass-production soldering process used in electronics manufacturing where a printed circuit board is passed over a wave of molten solder. The technique is mainly applied to through-hole components and mixed-technology boards, and is often used in conjunction with surface-mount assemblies that are already reflow-soldered. It is distinct from reflow soldering, which melts solder paste on the entire surface of the board.

The basic flow involves applying flux to the board, preheating to activate the flux and reduce thermal shock, and then passing the board over a standing wave of molten solder. The solder wets exposed copper surfaces on pads and component leads, forming fillets, after which the board is cooled to solidify the joints. Variants include open wave and submerged wave soldering. Flux can be rosin, water-soluble, or no-clean, depending on requirements and post-solder cleaning practices.

Equipment and process control are important for quality. A typical system includes a fluxer, preheater zones, a solder pot with a nozzle or submerged bath, a conveyor to carry the board, wave height and speed controls, and a cooling section. Alloys used include traditional leaded tin–lead solders and lead-free alternatives such as SAC alloys. Temperature and dwell time are carefully controlled to promote wetting while minimizing defects such as solder bridges, cold joints, or tombstoning.

Applications and limitations: wavesoldering offers high throughput and cost efficiency for boards with through-hole components and mixed assemblies but is less suitable for densely populated or fine-pitch surface-mount features. It has environmental and safety considerations related to flux use and solder composition, and regulatory requirements influence material choices and handling.