The surface to be soldered must be cleaned & fluxed. The soldering iron switched on and bellowed to attain soldering temperature. The solder in form of wire is allied hear the component to be soldered and heated with iron. The surface to be soldered is filled, iron is removed and joint is cold without disturbing.

Solder Joints Are Supposed To:

Provide permanent low resistance path. Make a robust mechanical link between P.C.B. and leads of components. Allow heat flow between component, joining elements and P.C.B.

The following precaution should be taken while soldering:

Use always an iron plated copper core tip for soldering iron. Slightly for the tip with a cut file when it is cold. Use a wet sponge to wipe out dirt from the tip before Soldering instead of asking the iron.

Tighten the tip screw if necessary before iron is connected to Power supply. Clean component lead and copper pad before soldering.

Apply solder between component leads, P.C.B. pattern and tip of soldering iron. Iron should be kept in contact with the joint for 2-3 seconds only instead of keeping for very long or very small time. 

Cutting the leads:

Once we get our components, soldered into the circuit board, Surface mounting components onto a circuit board and takes the leads push through holes in the board, which some say is the easier of the two methods of soldering small components onto boards.