What is Soldering? – Definition & Theory

Soldering is a process of jointing two piece of metal with the help of a third metal called solder. It is done at a low temperature not at higher temperature. The solder used is an alloy of lead and tin. The solder forms a surface uniform, and increases the mechanical strength of the joint. It increases the conductivity of the joint, fill up the gap in the joint.

For different purpose different solders are used as.

Electrical Purpose

  • Tin – 95%
  • Lead – 5%
  • Melting point – 200C

Cable joint soldering

  • Tin – 67%
  • Lead – 33%
  • Melting point – 190C

Soldering joints

  • Tin – 60%
  • Lead – 40%
  • Melting point – 192C

Ordinary soldering

  • Tin – 50%
  • Lead – 50%
  • Melting point – 205C

It is important that the melting temperature of the solder must be less than the metal to be soldered.

What is Flux?

For soldering the jobs, the flux is needed, these are the main functions of the flux;

  • It cleans the job.
  • It helps the solder to spread uniformly over the job.
  • It maintain the temperature of the solder and the solder does not cool soon.
  • It prevents the oxidation of the metal or jobs.

Resin, the flux which is known as fluxite, is used for soldering when lead tin alloy is used as the solder.

Procedure of soldering. Take the following steps:

(i) Clean the part or job to be soldered.

(ii) Heat the part to be soldered.

(iil) Carry the flux on the spot and then apply solder.

(iv) When the job has been soldered properly remove the soldering iron and clean the part which is soldered.

What is brazing?

Soldering at higher temperature using brass as solder is called brazing. Brazing is used where the strong joint is and welding is not possible. In soldering and brazing the metal to be soldered does not melt and fill up the gap.

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