Why do electric soldering irons use colophony?
Rosin serves as a soldering flux in welding, playing a soldering role. In theory, the melting point of flux is lower than that of solder, and its specific gravity, viscosity, and surface tension are all lower than that of solder. Therefore, during welding, the flux melts first, quickly flows and covers the surface of the solder, isolating air and preventing oxidation of the metal surface. It can react with the surface oxide film of solder and the soldered metal at high temperatures to melt and restore a pure metal surface. Proper soldering helps to produce satisfactory solder joint shapes and maintain the surface gloss of the solder joints.
Rosin is the most commonly used solder, which is neutral and does not corrode circuit components and soldering iron tips. If it is a newly printed circuit board, a layer of loose perfume should be coated on the surface of the copper foil before welding. If it is a pre made circuit board, it can be directly soldered. In fact, the use of rosin depends on personal habits. Some people will soak the soldering iron tip on the rosin after welding each component; I always soak some rosin on the tip of the soldering iron when it is oxidized and inconvenient to use. The use of rosin is also very simple. Open the rosin box and soak the powered soldering iron tip on it. If solid solder is used during welding, adding some rosin is necessary; If rosin tin solder wire is used (with flux wrapped inside the wire core), rosin can be omitted.
Due to the formation of an oxide film on the metal surface after contact with air, the higher the temperature, the more severe the oxidation. This oxide film prevents the wetting effect of liquid solder on the metal, just like oil on glass prevents water from wetting. Flux is a specialized material used to remove oxide films, also known as flux.
Flux has three main functions:
1. Remove the oxide film. The essence is that the substances in the flux undergo a reduction reaction, thereby removing the oxide film, and the reaction products become suspended slag, floating on the surface of the solder.
2. Reducing surface tension and increasing solder flowability can help wet solder joints.
3. Prevent oxidation. After melting, it floats on the surface of the solder, forming an isolation layer, thus preventing oxidation of the welding surface.
