Soldering is defined as a group of joining processes that produce coalescence of materials by heating them to the soldering temperature and by using of filler metal (solder) having a liquidus not exceeding 450 C degrees and below the solidus of the base metal. The solder is distributed between closely fitted faying surfaces of the joint by capillary action. Principles and Practices in soldering The metallurgical solder joint is produced by reaction of the base metal and the filler metal. The solder alloy is applied as a liquid metal that wets and spreads in the joint’ and generaly forms a layer of an intermetallic compound with a small amount of the base metal. Upon solidification’ the joint is held together by the same attraction between adjacent atoms that holds a piece of solid metal together. A sound soldered joint is achieved by the selection and use of proper materials and processes. Soldering is an attractive metal joining process. A major factor of in its popularity is that such a low temperature process has minimum effect on base metal properties. A wide range of heating methods can be adopted, giving flexibility in design and manufacturing procedures. The occasional defective soldered joints can be easily repaired. Soldering technology is an essential technique in modern industry.