Soldering

Soldering is defined as a metal joining process wherein coalescence is produced by heating the surfaces to be joined to a suitable temperature and melting the filler metal, which is a fusible alloy called solder (melting point usually less than 427'c), so that it may be distributed between properly fitted surfaces of the joint through capillary action. Soldering operation is performed by bringing molten solder in contact with the preheated surfaces (being joined) and heating the joint area to a good wetting temperature (about

55 to 80'c above the melting point of soldering alloy). The solder is then left to cool and freeze as quickly as possible to avoid development of internal micro cracks in the joint. The principle underlying soldering is that when the surfaces to be joined are cleaned off well from oxides, they can be joined together using molten solder that may adhere easily to the work piece surfaces due to molecular attraction. The molecules of solder entwine the parent metal molecules and form a strong bond. The various joints of soldering shown in figure.

Figure-Soldering