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Ready, steady, solder

See how we stick metals together with solder alloy, and learn how to safely master a useful skill for life.
Plan a session with this activity

You will need

  • Clips or clamps
  • Components for the project of your choice
  • Safety glasses
  • Solder
  • Solder removing tool
  • Soldering iron
  • Soldering sponge

Before you begin

  • The Institution of Engineering and Technology (IET) have produced resources to guide you through a number of different plans and projects using soldering, which can be found here.
  • Try to encourage everyone to come to this session in old clothes, with long hair tied back and no dangling jewellery or accessories.
  • Make sure the working area is clean and tidy, with easy access to your electrical supply. You should be able to switch everything off quickly in case something goes wrong.

Run the activity

  1. Share this safety advice for soldering with the group:
    • Check the mains cable of your soldering iron before you plug it in. If it’s damaged, don’t use it! Keep the cable clear of the soldering iron, so that it isn’t damaged by the heat.
    • Never touch the tip of the soldering iron! It gets extremely hot (350 degrees) and will melt your fingers as well as the solder.
    • Always put the soldering iron back in its stand whenever you’re not using it, to prevent damage to anything else that could be burned or melted, including you!
    • Wear safety glasses when soldering and finishing your circuits. Solder can spit and sometimes the ends of components can fly off if you trim them.
    • Work in a well-ventilated area to avoid inhaling too many nasty fumes from the ‘flux’ that burns off from the solder. Remember to take regular breaks if soldering for a long time.
    • Always wash your hands after you’ve handled the solder.
  1. Gather all the components together for the circuits you’ll be working on. Make sure everything’s as it should be. Check voltages and resistance values before soldering anything, so you can be sure that the circuit will work. Remember to handle the components with care throughout, so nothing breaks.
  2. Dampen the sponge that’s on the soldering iron stand. This just needs to be damp, not soaking wet. Do this carefully, drying any drips from surfaces and moisture from hands before continuing.
  3. Put the iron on its stand, switch it on and let it heat for a few minutes.
  4. Touch the end of the iron gently against the damp sponge. If it steams, the iron is hot enough to use. Carefully wipe clean the tip of the iron with the sponge.
  5. Take your solder and melt a little on the tip of the iron. Do this until the tip is coated.
  1. Touch the tip of the soldering iron against the joint you want to solder and hold it there a few seconds. Try to keep it in contact with both the sides you’re soldering together.
  2. Touch the solder against the joint you’ve just heated up. Some should run and form into a volcano-shaped peak that connects the two sides. Don’t touch the solder against the iron itself.
  3. Remove the solder and then the iron. Your components need to stay in place until the liquid solder has cooled. Clamp them in place, if you can.
  4.  Clean the iron again with the sponge to remove any remnant of solder, return it to the stand and switch it off. Leave it to cool too.
  5.  Check back to see whether your solder has hardened. Treat your new joint with care, as it may still be delicate.
  6.  Share these extra tips with anyone who fancies trying out some more soldering:
    • Some electronic components, such as IC (integrated circuit) chips are easily damaged by too much heat. To avoid damaging components while soldering them, you can attach a crocodile clip to the component lead between the component body and the joint you’re soldering. The crocodile clip will act as a heat sink, drawing the heat away and stopping the component from overheating.
    • Get everything in the right place. Make sure you know what all your components are and where they need to go before you start. You could print out the circuit diagram for your project and tape the components to it so that you can find them easily when you start building your circuit.
    • If you find you want to remove some solder then you may need to use a solder removal tool. This sucks up melted solder so that you can remove the component and start again.

Reflection

Being able to solder lets you repair metal objects, make your own circuits and could even get you a job one day. It’s an example of a fine motor skill, as it involves working with small, fiddly bits and pieces in a precise way. How might knowing how to solder help us learn other fine motor skills, like building circuit boards?

Other examples of fine motor skills include writing, typing, buttoning up clothing and using cutlery. They are small things that add up to make a big difference. Just like these, soldering is a skill that’ll become easy with practice and can be just as useful.

Safety

Soldering

Soldering irons produce a lot of heat. Never touch the tip of the soldering iron on anything other than the things you’re soldering and use tweezers or clamps to hold things in place. Never solder near flammable gases or liquids or combustible materials such as wood, textiles, or paper. Make sure there’s a fire extinguisher and a first aid kit (with items to treat burns) nearby.

Wear non-flammable clothing, gloves, safety goggles, and closed-toe shoes. Cover your arms and legs to prevent burns and remove loose clothing (such as scarves).

Work in a well-ventilated area to avoid inhaling fumes and keep food and drink away from the working area to avoid contamination.

Electronics

Remove any equipment you’re working on from the power source before you begin. Never assume the power circuit’s off – test it with a voltmeter (and then test it again to be sure).

Only connect power to a circuit once you’ve finished working on it and have checked your work. Make sure your circuit isn’t overloaded, and return any covers you’ve removed.

Make sure that all electronics equipment is properly grounded. Use the right electronics tools, and always replace damaged equipment (for example, replace cables rather than repairing them with insulating tape). Always have safety equipment including a fire extinguisher, basic first aid kit, and mobile phone nearby.

Science

Supervise young people, and only do science activities that are advised and age appropriate for your section. Test activities first, to make sure you’re confident you can lead them safely. Use protective clothing where necessary.

Sharp objects

Teach young people how to use sharp objects safely. Supervise them appropriately throughout. Store all sharp objects securely, out of the reach of young people.

Glue and solvents

Supervise young people appropriately when they’re using glue and solvent products. Make sure there’s plenty of ventilation. Be aware of any medical conditions which could be affected by glue or solvent use and make adjustments as needed.