Solder paste is a medium activity flux in the form of a paste, based on rosin and organic halogen activator, for easy soldering of copper, silver, zinc and nickel items. It is used in lead-tinning and soldering in the radio and telecommunication technology as well as in installation of electrical equipment. Post-soldering flux residues do not cause corrosion of non-ferrous metals and may remain on the joints. (it is advisable to wash them with alcohol remover). The product is used where rosin is not enough.