2-Way Radios

How To Make a Good Solder Joint

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WARNING: This work refers to electrical soldering only.

Learning the correct technique means you can ensure trouble free soldered electrical joints which will be reliable over a long time, and progress to make cheap, easy repairs to your electrical equipment if they develop simple circuit joint faults.

  • Make sure it’s clean. Printed Circuit Boards (PCBs) may need washing – use a mild soap or detergent, but rinse thoroughly and blot on a paper towel, allowing the PCB to dry completely.
  • Clean component leads by lightly scraping with a blade or use emery or wet and dry paper, used dry. Flux helps to clean the joint and may help if sparingly applied to a reworked joint.
  • Ensure the join is mechanically stable. Solder is not really a glue; it provides electrical continuity for reliable circuitry. If components move during soldering, the joint may be unreliable or fail completely.
  • Use a suitable-size soldering iron with a clean bit. Using too small a bit for larger solder joints is inefficient and may heat the joint unevenly. This may cause the ‘solder’ to set in different strata/layers and prove to be an electrically poor joint – known as a ‘dry joint’. Conversely, using too large a bit is unwieldy and may overheat components which may fail completely.
  • Check the tip temperature. You can do this by touching the tip with the end of the solder, which should melt immediately forming a thin film, tinning the end of the tip. This helps to conduct heat to the work evenly. If the tip is not up to working temperature, leave it a little longer to come up to temperature.
  • Heat the joint – component leads and PCB pads – for a brief time (

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