13.1 What is Soldering?

Soldering is a process for joining metal parts by making use of any of the various fusible alloys (solder), whose melting temperature is lower than that of the material to be joined, and whereby the surface of the parts create an intermolecular bond, without becoming molten.

Soldering can be classified as soft soldering (soldering), which takes place at temperatures below 450 C and hard soldering (brazing), which is done at temperatures above 450 C. Hard soldering is commonly employed on such metals as silver, gold, steel and bronze where in it makes a much stronger joint than soft soldering, the shearing strength being 20 to 30 times higher. However, both thermal joining processes are generally termed as soldering, because in both cases, the molten metal (solder) is drawn into the capillary gap between two closely fitting clean solid metal surfaces.

A soldered connection ensures metal continuity. On the other hand, when two metals are joined to behave like a single solid metal by bolting, or physically attaching to each other, the connection could be discontinuous. Sometimes, if there is an insulating film of oxides on the surfaces of the metals, they may not be even in physical contact. The disadvantages of mechanical joints versus soldering are that oxidation will continually occur on the surface and will increase the electrical resistance. Moreover, vibration and other mechanical shocks may later make the joint loose. A soldered connection does away with both of these problems. There is no movement...