In the current wave soldering, lead-free wave soldering system, the general use of dual-wave soldering. During wave soldering, the PCB touches the first peak and then the second peak.

The first crest is a turbulent wave crest jetted by a narrow nozzle with a fast flow rate and high vertical pressure on the assembly which allows the solder to have better permeability to the soldered ends of surface mounted components with small dimensions and high mounting density ; The turbulent molten solder scrubs the surface of the assembly in all directions to improve the wettability of the solder and overcome the problems associated with the complex shape and orientation of the components while also overcoming the shadowing effect of the solder, The jet force is sufficient to allow flux gas to drain. Therefore, there is no influence of flux gas even if no vent holes are provided on the printed board, so that welding defects such as leaky welding, bridging and insufficient weld bead are greatly reduced, and the welding reliability is improved.

After the first peak of the product, due to a short immersion tin and parts of the cooling itself and other factors, after immersion tin there are many short circuit, much tin, solder joint finish abnormal and welding strength is not enough and other undesirable content.

Therefore, the subsequent correction of poor immersion of tin was carried out by a secondary jet with a relatively wide jet stream surface and a more stable second peak. This is a smooth crest with slow flow rate that is conducive to the formation of a substantial weld while also effectively removing excess solder from the weld end and wetting the solder on all the weld surfaces with a modified weld surface that eliminates Possibility of tip and bridge, obtain full weld without defects, and ultimately ensure the reliability of component welding. The proper cooling after immersion tin helps to improve the bonding strength of the solder joint. At the same time, the cooled product is more conducive to the operation of the furnace operator. Therefore, the product after immersion tin needs to be cooled.