Solder is an alloy of two or more metals and is used to join metallic surfaces together when melted by soldering iron. The most common alloy used is 60/40-Tin/Lead and has a melting point of 374 deg. F (190 deg. C). Most soldering jobs can be done with flux cored solder (solder wire with flux in multiple cores). The surfaces to be joined have to be cleaned of dirt, grease, rust, soot etc. before soldering. The flux aids in cleaning oxides off the surfaces to be soldered.
Solder should have following qualities for best performance.
The organic, non-corrosive fluxes are used in electrical soldering. The most common flux used is a rosin flux (a kind of resin-organic compound insoluble in water) which is non-corrosive and non-conductive. Prior cleaning of electrical components is generally not necessary when using active rosin cored solder. However, flux will not remove grease or oil from surfaces. It only removes thin oxide/tarnish. The solder is also available without the inner flux core, for use with liquid/solid flux.
ANU Engineering - ENGN2211