1. The printed circuit board runs forward with the conveyor belt from the entrance end of the wave soldering machine, and when it passes through the flux foaming tank (or spraying device), a thin layer of flux is evenly coated on the lower surface of the printed circuit board, all component ends and pin surfaces.
2. As the printed circuit board running with the conveyor belt enters the preheating zone (preheating temperature is 90 ~ 130℃), the solvent in the flux is volatilized, thus reducing the gas generated during welding.
3. Rosin and active agent in flux begin to decompose and activate, which can remove pollutants such as oxide film on printed circuit board pads, component ends and pins, and at the same time protect the metal surface from re-oxidation.
4. The printed circuit board and components are fully preheated, which can avoid the damage of thermal stress caused by the sharp rise of temperature during welding.
5. The printed circuit board continues to move forward, and its bottom surface first passes through the first melted solder wave, which is a chaotic wave (i.e. turbulent wave or vibration wave). The solder hits all the pads on the bottom of the printed circuit board, the welding terminals and pins of the components, and the molten solder permeates and diffuses to the metal surface purified by the flux. "Turbulence" has a high peak velocity and great vertical pressure on SMT components, which makes the solder have good permeability to solder joints with small size and high installation density, and overcomes the adverse effects caused by complex component shapes and "shadowing effect"; At the same time, the upward jet force of turbulent waves can make the flux gas discharge smoothly, greatly reducing the defects such as missing welding and incomplete penetration.
6. The bottom surface of the printed circuit board passes through the second molten solder wave. Because the second solder wave is a smooth wave, the solder flow rate is slow, and the flow rate at the outlet is almost zero, so the redundant solder on the terminal can be effectively removed, so that all the welding surfaces are well wetted, and the pulling and bridging caused by the first wave peak can be fully corrected.
7. When the printed circuit board continues to move forward and leaves the second solder wave, it is naturally cooled to form solder joints, that is, wave soldering is completed.
Wave soldering machine means that the soft solder (lead-tin alloy) that melts du is sprayed into the solder wave crest required by the design by an electric pump or an electromagnetic pump, or it can be formed by injecting nitrogen into the solder pool, so that the printed board with pre-installed components passes through the solder wave crest, and the mechanical and electrical connection between the solder terminal or pin of the component and the solder pad of the printed board is realized. According to the wave crests with different geometric shapes used by the machine, the wave soldering system can be divided into many types.