Wave soldering refers to the process of injecting molten soft solder (lead-tin alloy) into the designed solder wave through an electric pump or electromagnetic pump. It can also be formed by injecting nitrogen gas into the solder pool. Printed circuit boards with pre installed components are used to achieve mechanical and electrical connections between the solder ends or pins of the components and the solder pads of the printed circuit board through the solder wave.

After the PCB circuit board enters the wave soldering machine through a conveyor belt, it will pass through a certain form of flux coating device. Here, the flux is dispersed onto the circuit through wave soldering, foaming, or spraying methods. Since most flux must reach and maintain an activation temperature during welding to ensure complete wetting of the solder joints, the circuit board needs to pass through a preheating zone before entering the wave soldering slot. The preheating after the application of flux can gradually increase the temperature of the PCB and activate the flux, which can also reduce the thermal shock generated when the assembly enters the pollution peak. It can also be used to evaporate any moisture that may be absorbed or dilute the carrier solvent of the soldering flux. If these things are not removed, they will boil and cause tin sputtering when passing the wave peak, or form steam that remains inside the soldering tin to form hollow solder joints or sand holes. In addition, due to the large heat capacity of double-sided panels and multi-layer panels, they require higher preheating temperatures than single panels.

Currently, wave soldering machines mainly use thermal radiation for preheating, and the most commonly used wave soldering preheating methods include forced hot air convection, electric plate convection, electric rod heating, and infrared heating. Among these methods, forced thermal convection is usually considered the most effective heat transfer method for wave soldering machines in most processes. After preheating, the circuit board uses a single wave（ λ Wave or double wave (disturbance wave and λ Welding is carried out using the wave method. For perforated components, a single wave is sufficient. When the circuit board enters the wave ridge, the direction of solder flow is opposite to the direction of the board's travel, which can generate eddy currents around the component pins. This is like a washing process, which removes all residual flux and oxide film from the solder joint and forms wetting when the solder joint reaches the wetting temperature.

For mixed technology assembly parts, generally λ The wavefront also uses turbulence waves. This type of wave is relatively narrow and carries a high vertical pressure during disturbance, which allows solder to penetrate well between tightly placed pins and surface mounted component (SMD) pads, and then use λ Wave completes the formation of solder joints. Before making any evaluations of future equipment and suppliers, it is necessary to determine all technical specifications of the boards welded using wave crests, as these can determine the performance of the required machines.