Basic Soldering Guide Part 3 – Soldering Troubleshooter

Alan Winstanley covers a quick summary plus tips on trouble shooting solder joints and safety in this third instalment of an article originally reproduced by Everyday Practical Electronics magazine

© Alan Winstanley 1997-2010

Quick Summary Guide

To round off our practical guide to soldering, here’s a summary of how to make the perfect solder joint.

  1. All parts must be clean and free from dirt and contamination.
  2. Try to secure the work firmly to aid accuracy.
  3. Clean the tip of the hot soldering iron on a damp sponge.
  4. “Tin” the iron tip by applying a small amount of solder. Do this immediately, with new tips being used for the first time.
  5. Try to heat all parts of the joint with the iron for under a second or so, to bring them up to the same temperature.
  6. Continue heating and apply sufficient solder to form an adequate joint. It only takes two or three seconds at most, to solder the average p.c.b. joint.
  7. Remove the iron and return it safely to its stand.
  8. Do not move parts until the solder has cooled.

Troubleshooting Guide

The perfect solder joint should be quite shiny and smooth after cooling down. Here is a quick troubleshooting guide to help resolve any problems encountered with troublesome solder joints.

Solder won’t “take” or won’t flow properly to cover the joint.
  1. Grease or dirt present;
  2. Material may not be suitable for soldering with lead/tin solder.
  1. Desolder and treat parts with solvent or abrasive cleaners etc. as required;
  2. Use alternative type of solder alloy, or perhaps file away any plating to reveal base metal beneath.
Joint is crystalline or grainy-looking.
  1. Joint has been moved before being allowed to cool naturally;
  2. Joint was not heated adequately (too large a joint and/ or the iron temperature or power rating is too low).
  1. Desolder and remake.
  2. Use a more appropriate iron for the task, also check the temperature settings.
Solder joint forms a “spike” and applying the iron again makes it even worse! Probably overheated, burning
away the flux. The iron, when removed, would cause the solder to stand up in a spike.
It is usually best to desolder and remake the joint properly.


Potential Hazards and Simple First Aid

It is very seldom that soldering iron operators receive any burns or other injuries from the use of hot soldering irons. The technique is perfectly safe provided that common sense precautions are taken during the soldering operation. Here are a variety of precautions worth bearing in mind:

  • Components are obviously very hot after soldering, so let them cool before handling them to avoid skin burns.
  • Beware of splashes of molten solder caused by careless handling of a hot soldering iron.
  • Always park a hot iron safely on a stand in between use — never hang it vertically next to the bench.
  • Beware of wire offcuts flying off (danger to eyesight) when snipping wires to length before or after soldering.
  • Avoid the inhalation of fumes if at all possible as they can irritate the eyes or respiratory tracts.

If you are unlucky enough to receive a more serious skin burn which requires attention, the very first thing to do is cool the affected area immediately. Use plenty of cold running water, for example. Remove any objects which may prove constrictive, before any swelling starts (rings, watches, bracelets). Apply cold water for at least ten minutes and seek medical attention.

Finally, why not try your hand with one of the constructional projects described every month in Everyday Practical Electronics? Assembling a project successfully using your own bare hands is immensely satisfying and there is usually something for everyone in each monthly issue and constructing prototypes at home is an excellent way of gaining valuable experience in the art of soldering.

<<Part 1   <<Part 2

The on-line version of the Basic Soldering Guide (with colour photo gallery) can be accessed at

Other useful web sites:

Text and Photographs © Copyright © Alan Winstanley 1997-2010 The author can be contacted by


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