Why is rosin used by electric soldering irons?
Rosin is used as a flux in welding and acts as a flux. Theoretically speaking, the melting point of flux is lower than that of solder, and its specific gravity, viscosity, and surface tension are smaller than that of solder. Therefore, when soldering, the flux melts first, and quickly flows and covers the surface of the solder to isolate the air and prevent the metal surface. Oxidation, and can react with the oxide film on the surface of the solder and the metal to be welded at high temperature to melt it and restore the pure metal surface. Appropriate soldering tin helps to solder out a satisfactory solder joint shape and maintain the surface gloss of the solder joints.
Rosin is the most commonly used flux, it is neutral and will not corrode circuit components and soldering iron tips. If it is a newly printed circuit board, apply a layer of rosin perfume on the surface of the copper foil before soldering. If it is a circuit board that has already been made, it can be directly soldered. In fact, the use of rosin depends on personal habits. Some people will dip the tip of the soldering iron in rosin every time they solder a component; Dip some rosin on top. The use of rosin is also very simple, just open the rosin box and dip the tip of the energized soldering iron on it. If solid core solder is used for welding, it is necessary to add some rosin; if rosin tin soldering wire is used (flux is wrapped in the wire core), rosin may not be used.
Since the metal surface will form a layer of oxide film after contact with air, the higher the temperature, the more severe the oxidation. This layer of oxide film prevents liquid solder from wetting the metal, just as oil on the glass will prevent water from wetting. Flux is a special material used to remove oxide film, also known as flux.
Flux has three functions:
1. Remove oxide film. The essence is that the substances in the flux undergo a reduction reaction, thereby removing the oxide film, and the reaction product becomes suspended slag, floating on the surface of the solder.
2. Reduce the surface tension, increase the fluidity of the solder, and help the solder to wet the weldment.
3. Prevent oxidation. After it melts, it floats on the surface of the solder, forming an isolation layer, thus preventing oxidation of the soldering surface.
