Beginners Guide to Soldering

Beginners Guide to Soldering

Soldering is a very handy skill required by every hardware hacker and maker to either make small changes, repair a project or build complete prototypes. Soldering isn’t a skill that can be learnt overnight, it takes like anything else quite a bit of practice, a lot of trial and error to perfect the art.

Once mastered your skill will be used frequently from repairing frayed wires to replacing battery boxes on toys, so taking the time to learn it is essential. Although the process is fairly simple, everyone has their own tips and techniques to soldering, and will go down in to the amount of flux, tip temperature or content in the solder wire itself. So for the time being, learn the process then adapt it to what works best for you or your situation.

What you will need:

  • Soldering Iron
  • Solder
  • Stand
  • Tip Cleaner
  • Desolder Pump/Braid
  • Wire strippers
  • Wire cutters
  • Safety glasses
  • Helping hands grip stand

 

You may need:

  • Insulating tape
  • Heat shrink
  • Tweezers (for surface components)

 

What is soldering?

Soldering is the process of joining two pieces of metal together (i.e. the ends of wires, a component to a circuit board) with solder to create a secure joint that facilitates the flow of electricity.

Solder-Example

Through hole soldering is the soldering of components with legs that go through the PCB to be soldered on the reverse side, hence the name ‘through hole’, as they literally go through a hole on your circuit board. Surface mount components (commonly shortened to SMD – surface mount device or SMT – surface mount technology) sit on pads on top of the circuit board and are usually soldered on by machines as the components are considerably smaller than through hole components and they have to be placed and soldered precisely, they can be hand soldered but that is a more advanced level of soldering. This guide will help you start to solder through hole components and simple wires.

Through HoleSurface Mount Wire to wire

Safety Notes

Safety is important!

•    Soldering irons can get up to 450 degrees Celsius, you must use a stand and never touch the tip of the soldering iron.
•    Don’t place the soldering iron down on your workspace and keep your tools and components well away from the soldering iron.
•    Solder can spit when heated, safety goggles are recommended.
•    Always solder in a well ventilated area, and do not breathe in the smoke, even if you use lead free solder! Using a fan or extractor is recommended.
•    Wires and components will get hot, use clips or helping hands to hold things steady and protect your fingers

Practice

Practice makes perfect, and soldering is a skill that can be improved!
Practice as much as possible on old circuit boards or wires before you start your real project. It doesn’t matter if you make mistakes, try different techniques, find a way of holding the soldering iron that suits you, work out how much solder you need and how long to keep the solder and tip in place.

The idea is to make sure the two parts are firmly fixed together, the solder on a through hole component should make a neat and shiny molehill shape mound of solder.

GPIO Assembled Cobbler - cpc.docx solder3

Start up steps

  • Ensure your iron is stored safely in a stand
  • Turn on your soldering iron and allow it to heat up
  • Collect your materials, such as PCB and components, solder wire and solder tip cleaner

Quick start how to:

Place your hot soldering iron on the part to be soldered
solder4
Touch the soldering wire to the edge of the soldering iron tip and let it melt around the component
solder2
Remove the soldering iron and allow to cool
solder5

 

Soldering through hole components

Secure your circuit board with your helping hands stand, or blue tack
Check if your component has to be soldered a specific way, it is important you check each of your components before you begin soldering.

These common components DO usually have +/- sides, these need to correspond with your +/- current flow;
LEDs
Transistors
Electrolytic capacitors
Diodes

These common components DO NOT usually have +/- sides, and can usually be soldered any way around;
Headers
Resistors
Fuses
Ceramic capacitors

Push the legs of your component though the hole, making sure you have correctly identified the polarity of the component to be soldered and the side of the board the component should sit on. You can bend the leads of components with longer leads to help secure it in place.

solder6

Hold the soldering iron tip to the leg of the component you want to solder, touch the solder wire to the side of the tip and allow it to melt, remove the tip when enough solder has been applied.

solder7

Cut off the excess of the components’ leg using wire cutters to give a good finish and avoid accidental short outs.

solder8

Soldering wires together

Strip the plastic off just the ends of the wires to expose the inner wire, a length of 5-10mm is good.

wire1

Tin the exposed wires to give them a solderable surface by applying a little bit of solder to just one bare wire using the iron and solder wire.

wire2

Use something to hold the two wires in place, like blue tack or a helping hands stand.
Apply the soldering iron to the two wires, making sure a good amount of solder wire is applied to hold them together.

wire3

Allow the wires to cool down and cover the join with insulating tape or heat shrink.

wire4

Tinning

This is a process where you apply solder to the component, tip or wire before you attempt to join them, this provides a surface that is better suited to transfer heat and getting solder to stick.

Made a mistake?

Oops! Don’t worry use a desoldering pump or desoldering braid to clean up and remove solder, both of these work by reheating the solder with your iron and removing it by suction or melting it into copper braid, the easiest method is the desolder pump.

Tips:
•    New soldering irons may need the tip ‘tinning’ to provide the proper transfer of heat, apply a small amount of solder to the tip to give it a good surface to transfer heat
•    Use a damp sponge or brass tip cleaner to remove build up on your soldering iron tip
•    Never leave your soldering iron switched on when not in use, the oxygen in the atmosphere will oxidise on the tip and stop it from working efficiently
•    Your components will remain hot for some time after soldering, DO NOT touch them immediately afterwards, allow the component to cool down
•    Solder can spit when heated, use eye protection and cover you work surface to avoid damaging the table
•    Wash your hands with soap and water after you have finished