Solder Flux

Fluxed solder or solder with flux inside, also known as tubular solder. This is a hollow rod, in the core of which there is a flux. The rod melts during the soldering process, due to which the flux is released and performs its protective function.

Soldering fluxes are divided into two groups:

• chemically active
• chemically passive.

The structure of active fluxes includes substances such as hydrochloric acid and zinc chloride. All of them destroy plaque and signs of corrosion well. Not used in everyday soldering and require proper qualification. Safety techniques when working with chemically active fluxes must be observed, otherwise there is a risk of burns, and in case of inept handling – deterioration of the material. There is none in radio electronics, as active fluxes tend to corrode the textolite. After each use, clean the soldering area from the remains of the active flux to avoid the appearance of new corrosion.

The structure of chemically passive fluxes contains organic matter. They do not have pronounced oxidizing properties and are therefore often used for soldering radio elements. Weakly active fluxes are able to remove grease and dirt, protect the soldering area from oxidation, but are not designed to remove corrosion or rust.

How to choose solder and flux?

Most modern equipment works with a soldering temperature of 200 °C, and for soldering radio electronics it is already recommended to choose rods with a melting temperature of up to 140 °C. The algorithm is simple – for soldering thick wires, use solders with a high melting point, and vice versa for thin ones.