How to Fix a Corroded Circuit Board

Written by ed wagner
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How to Fix a Corroded Circuit Board
Temperature controlled soldering iron (Hemera Technologies/PhotoObjects.net/Getty Images)

Corrosion on printed circuit boards can range from simple tarnish on pads to damaged or destroyed runs. Likewise, repairs range from simple to complex. An experienced technician should estimate the time and cost of a repair as compared to replacing the entire board assembly.

Skill level:
Moderately Challenging

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Things you need

  • Pencil eraser
  • Cotton swabs
  • Alcohol
  • Hobby knife
  • Bus wire
  • Rosin flux
  • Temperature controlled soldering iron
  • Solder
  • Solder wick
  • Board repair kit with runs and eyelets
  • Epoxy
  • Conformal coating

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Instructions

  1. 1

    Repair a tarnished copper pad by cleaning it with a pencil eraser. A tarnished pad has a dull brown colour. Polish it with the eraser, then clean it with cotton swabs and alcohol. Cleaning is important because the eraser gets its colour from some oils that should not be left on the board. A tarnished pad or one contaminated by oil will not bond with solder. The resulting joint will have a convex appearance much like a drop of water, while the desired joint should have uniform concave fillets.

    How to Fix a Corroded Circuit Board
    Use a pencil eraser to clean tarnished pads (NA/AbleStock.com/Getty Images)
  2. 2

    Repair a small corroded pad or run with a piece of bus wire. This is for a short run of half an inch or less. First, remove any remaining corrosive liquids with alcohol and cotton swabs. Cut the corroded run or pad, and remove the section. Form a piece of bus wire to replace it. Scrape the ends of the run to reveal copper. Apply flux and then tin to the ends with solder. Set the bus wire in place, and solder both ends. Clean up with cotton swabs and alcohol.

    How to Fix a Corroded Circuit Board
    Bus wire (Hemera Technologies/PhotoObjects.net/Getty Images)
  3. 3

    Repair long runs with replacement runs from the board repair kit. Cut out the damaged part. Select a run from the kit that is approximately the same width. It may be necessary to use several replacements if the original had any bends. Use the hobby knife to scrape down to the copper on the existing ends. Apply flux and then tin to the ends with solder. Carefully position the replacement run, and solder its ends. Clean up with alcohol. Tack the run in place with epoxy, and cover it with conformal coating.

    How to Fix a Corroded Circuit Board
    Runs and pads on a computer board (Photos.com/Photos.com/Getty Images)

Tips and warnings

  • Alcohol is flammable. Keep it away from a hot soldering iron.

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