Protecting PCB from corrosion and oxidation

Discussion in 'General Electronics Chat' started by cmartinez, May 27, 2015.

  1. cmartinez

    Thread Starter AAC Fanatic!

    Jan 17, 2007
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    I'd like to paint, or lacquer, the back of my in-house made (I hate the term home-made) PCB's. so as to protect them from deterioration and corrosion due to moisture.
    Can anyone recommend what specific type, or brand, of paint would be most suitable for this? I'd like it to look as professional as possible. Also, a link to your recommended product would be nice.
    Thanks in advance!
     
  2. DickCappels

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    Aug 21, 2008
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    I used to use Varathane brand polyester varnish to impregnate transformers and it would probably be good for coating PC boards. I also used it to fix up my weather-beaten wooden door :)
     
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  3. Kermit2

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  4. cmartinez

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  5. cmartinez

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    Thanks Dick. I did find the brand you've mentioned, though I found it in a polyurethane version, not polyester.
     
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  6. cmartinez

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    I wonder if the Almond green color shown in page 2 of this brochure would do the trick. Maybe if I applied it with an airbrush....
     
  7. MaxHeadRoom

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    I use the Conformal Coating same as commercial boards , bit of a devil to remove though when repairing.
    Max.
     
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  8. Dr.killjoy

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    Apr 28, 2013
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    What about using soldering paste to tin the whole board or using a running solution?? I have taken thicker solder and big tip iron and just coat my boards in the solder...
     
  9. Gdrumm

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    Aug 29, 2008
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    What precautions would need to be taken to prevent the board from drying out (and shrinking enough to cause problems a year or two from now)?
     
  10. ian field

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    Maplin stock cans of PCB laquer - but the stuff I bought from them seemed a bit prone to peeling, I cleaned the board with cellulose paint thinner, so it should have been OK.

    Wherever you get your etching supplies probably also stocks laquer.
     
  11. cmartinez

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    Good observation... I'll look into that and then get back with what I found. Thanks!
     
  12. ian field

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    When I built a motorcycle ignition module, I chose to melt an altar candle in a large tin and dip the board in it till it was up to the melting point.

    As it never sets, it doesn't crack, flake or peel - and its more waterproof than a coating that does any of those.

    And repairs are a doddle - you just apply the iron to any solder joints that need working as if the wax wasn't there. To complete a repair, you can either melt on some new wax where the old was disturbed, or cook up the melting tin and give it another dip.
     
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  13. AnalogKid

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    What you are describing is called conformal coating. It is used to protect pc boards from humid/corrosive/harsh environments like the salt spray of a ship's deck.
    http://en.wikipedia.org/wiki/Conformal_coating

    We use a single-part aerosol urethane with a UV dye. After air-drying overnight, we inspect it under a black light to see if there are any gaps in the coverage. Search for things like conformal coating spray cans and see what comes up.

    ak
     
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  14. nerdegutta

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    Dec 15, 2009
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    I'm using clear lack from Wurth or from Electrolube.
    lakk.JPG
    From left to right: This is a stuff that dissolve oxidation, This is a transparent protective lacquer, and to the right you have a clear transparent lacquer form Electrolube.

    If I get over a PCB with corrosion, I use this and a tooth brush, or a soft copper brush. Then I use isopropanol, and finally I spray it with lacquer.

    5v5a.JPG
    This is one of my latest boards. This is cleaned with isoprpanol and coated with the lacquer from Wuerth.
     
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  15. MaxHeadRoom

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    As I mentioned in a previous post.;)
    It certainly won't peel when applied correctly.
    Max.
     
  16. Dr.killjoy

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    What about using Liquid Electrical Tape too ?
     
  17. ian field

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    It was a prototype - as it turned out, it didn't need any further modification. The wax coating worked well enough, so there was no great urgency to change that either.
     
  18. cmartinez

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    Thanks Ian. One question, did you actually use wax, or was it paraffin?
     
  19. ian field

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    It was a melted altar candle as I mentioned previously.

    Many supermarkets stock them now.
     
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  20. cmartinez

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    Thanks for clarifying. I'm going to try that, see how it works.
     
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