| Intermediate Technology Education | Energy and Power Technology | Pre-Design | Topic 3 | Optional Activity 7 |


The purpose of this activity is to develop technological capability to complete introductory electrical/electronic soldering
  • Identify the tools and materials required for making electrical soldered connections.
  • Identify the correct procedure for tinning an electrical lead or contact point
  • Tin an electrical leads and contact points
  •  Identify the correct procedure for soldering one electrical lead or contact to another
  • Solder electrical leads together.

Tools and Equipment

Making soldered electrical connections requires very simple tools.

  • Wire cutter.  There are many types, but smaller ones are best.
  • Wire stripper.  Again many types are available, but simple inexpensive ones work fine.
  • Soldering iron.  An iron with a 25 to 40 watt very small, pointed tip works best. One designed for electrical use works best as it produces the correct temperature to heat the wire enough to melt the solder.
  • Solder.  Solder that is labeled for electrical use is required.  It has a resin (flux) core that cleans the contacts as it solders.
  • Holding jig.  A small device with a weighted base and arms with alligator clips, useful for holding small components for soldering.   

Samples are shown below.


Figure. Wire Cutter

Wire Stripper

Figure. Wire Stripper

Soldering Iron

Figure.  Electrical Soldering Iron.  Note the yellow sponge.  It is wetted and used to clean the iron.


Figure. Electrical Solder (Resin Core)

Holding Jig

Figure.  Holding Jig, sometimes called helping hands.


Tinning refers to the process of applying a thin coating of solder to the end of a lead on a component or the end of a wire.  This makes it easier to solder the components together. 

The process follows this sequence

  • Trim the wire or component lead to the correct length
  • Strip enough insulation to allow the connection to be made
  • Plug in the soldering iron and allow it to come to full temperature (5 to 10 minutes)
  • Clean the soldering iron tip, by wiping it a few times on a wet sponge or paper towel.
  • Mount the component or wire to be soldered securely in a holder or clip
  • Apply heat to the wire or lead
  • Put the tip of the solder on the wire or lead, away from the iron tip.  When it reaches the correct temperature, the solder will flow along the wire or lead.
  • Do not apply solder to the tip of the iron—it must be applied to the wire or lead.


Soldering is a joining process known as adhesion. Solder (a mixture of lead, tin and other materials) is melted around the join, and cools, holding the materials together.  When done properly, the solder will have a shiny appearance, not a dull one.

Soldering components or leads together follows this sequence

  • Prepare the components by tinning them
  • Place the components in contact along the area to be joined.  The strongest connections also have a good mechanical join (for example, a western union splice; the wire goes through hole; or is twisted), but often this is not possible. 
  • Apply heat to the leads (or wires, or contact points)
  • When the tinning begins to flow, apply additional solder to the components. 
  • Remove the heat and allow the parts to cool before moving them.  This last bit is important—moving the part before the solder has solidified with severely weaken the join both mechanically and electrically.

For More information

For more information on these topics, check out these web pages

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