Ruichi robots have come to give you benefits. Today, Ruichi Robots pushes a practical article for you – the principle of automatic soldering machine!
In the definition of “solder” in soldering machines, it can be found that “wetting” is the main role in the soldering process. The so-called solder is to wet the substrate with liquid “solder” to achieve the bonding effect. This phenomenon is like water flowing back on a solid surface, except that the weld solidifies into a joint as the temperature decreases. Theoretically, when tin is wetted onto the parent metal, the metal chemical bonds will combine between the two to form a continuous bond. However, in practical applications, the base metal will be eroded by the air and the surrounding environment, forming an oxide film to block the “solder”, so that it can not achieve a better wetting effect. This phenomenon is like pouring water on a substrate. If the oxide film on the surface of the substrate is not removed, even if it is hardly covered by the solder, its bonding force is weak.
First, Capillary Action If two clean metal surfaces are placed together and immersed in molten solder, the solder will wet the two metal surfaces and climb up to fill the gap between adjacent surfaces, which is capillary action. If the metal surface is not clean, no wetting and capillary action will occur and the solder will not fill this point. When the through-hole printed circuit board passes through the wave soldering furnace, the capillary force fills the holes with tin and forms a so-called “soldering strip” on the printed circuit board and is not completely the pressure of the tin waves.
Second, wet and non-wet A piece of greased metal sheet is immersed in water. No wetting. The water will form spherical water droplets and will shake off, so the water will not get wet or stick to the metal plate. If the metal plate is washed in a hot cleaning solvent, carefully dried, and then immersed in water, the water will completely diffuse to the surface of the metal plate, forming a thin and uniform film layer that will not collapse.
Third, cleaning When the metal plate is very clean, the water will wet its surface. Therefore, when the “solder surface” and the “metal surface” are also cleaned, the solder also wets the metal surface. Its cleanliness requirements are much higher than the water on the metal plate because the solder and metal must be tightly connected, otherwise. A very thin layer of oxide is formed between them immediately. Unfortunately, almost all metals oxidize immediately when exposed to air, and this very thin oxide layer can impede the wetting of the solder on the metal surface.
Fourth, the difference between welding and gluing When the two materials are glued together, their surfaces will bond to each other and become a mechanical bond between them. Because the glue is not easily fixed between the two, the bright surface cannot be as good as a rough or etched surface. Gluing is a surface phenomenon that can be removed from the original surface when the glue is wet. Soldering is the process of forming metal chemical bonds between solder and metal. The solder molecules penetrate into the molecular structure of the metal on the surface of the substrate to form a solid and complete metal structure. When the solder melts, it is impossible to completely remove it from the metal surface because it has become part of the base metal.