Hand soldering is done during PCB rework in a production unit when a PCB gets rejected or fails the quality pass test. Hand soldering is also done for repairing and servicing printed circuit boards by service centers.
Soldering Tools and Materials Needed for Hand Soldering
Soldering iron or soldering station: You need a good quality soldering iron or temperature controlled soldering station that run on electricity. If you are dealing with ESD-sensitive PCB and electronic components, then you need an ESD-safe soldering station. If you are doing lead-free soldering, you will probably need a temperature controlled soldering iron or soldering station with higher wattage because the melting point of lead-free solder is higher than tin-lead solder.
Solder wire: For a good solder joint, you need good quality of solder wire. Solder wires are available in tin-lead and Pb-Free compositions in different diameters.
Other soldering materials: Apart from soldering tools and solder wire, you may also need few other consumables like solder flux, solder paste, braid etc. Chemtronics is a worldwide leader in manufacturer and supply of PCB rework material.
Once you are ready with all the tools and equipments needed for hand soldering, you are ready to start the job. Start by making sure the PCB and the leads of the electronic components are clean and free from any contamination such as dust or grease. PCB or electronic components which are not clean may have deposited oxides that can lead to bad solder joint. Apply a good quality solder flux on the area of the PCB to be soldered and on to the leads of the components. Flux will help to remove any deposited oxides from the surface of the metals thus leading to better solder joints. You can use a flux pen to dispense flux.
Doing Hand Soldering
Now is the time to solder.
Make sure the soldering iron is hot. Do not touch it.
Hold the soldering iron properly in one hand and solder wire in the other hand. Maintain proper angle between the two. Try to use a solder wire reel stand that holds the reed of the wire so that you can pull the wire properly.
Place the solder wire at the point where the lead of the electronic components meets the copper track on the PCB.
Apply heat at the point where solder wire touches the lead of the component.
Once done, remove the soldering iron.
Cut extra leads of the electronic components.
A good solder joint should look shiny. Dull solder joint suggests something is wrong. If you are doing lead-free soldering, the joint will look dull in any case.