Fluxes

Flux / rosin

— additional materials used in soldering. More specifically, the common name for such materials is "fluxes", and rosin is just one of the varieties of fluxes.

The general purpose of all fluxes is to improve the "seize" efficiency of the solder during soldering. To do this, such compositions perform several functions at once. Firstly, they remove oxides and slags from the surface of the parts to be joined; secondly, they prevent the formation of new oxides on these surfaces; thirdly, they contribute to the spreading of liquid solder and more dense wetting of parts with it.

As for rosin, this is one of the most famous and common fluxes used in hand soldering. Rosin is extracted from the resin of coniferous trees, it is quite simple to obtain, as well as simple and safe to use. This type of flux can be used both in solid and liquid form (solution in ethyl or isopropyl alcohol). As for efficiency, molten rosin removes oxide films well on the surface of most metals, but it is poorly suited for heavily contaminated surfaces. Here, the use of other types of fluxes is more justified — in particular, acidic ones. The most popular type of such compositions is called “soldering acid”; it is an aqueous solution of zinc chloride. This is another type of flux often found commercially as a hand soldering consumable; however, be aware that soldering acid requires careful handling.