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Author Topic: Circuit trace sealant recommendations?  (Read 5559 times)
KU4UV
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Posts: 376




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« on: June 03, 2011, 05:28:16 PM »

Hello gang,

I Recently built a small kit and happened to accidentally nick a circuit trace on the underside of the circuit board.  The nick is quite small, but the copper trace is exposed.  I am wondering if anyone has any suggestions on a good way to seal the trace that I nicked?  The trace itself is still intact, I simply want to seal the trace from maybe rusting in the future.  Any tips or suggestions on what I can use to seal the trace?  I would think that something like polyurethane or finger nail gloss polish might work, however I don't want to use anything that could "eat away" at the board.  Any advice or suggestions?  Thank! Undecided

73,
Michael KU4UV
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KE3WD
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Posts: 5689




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« Reply #1 on: June 03, 2011, 06:00:57 PM »

1) It will never rust.  Because the traces are made of copper. 

2)  The coating is called "Solder Resist" and is applied only because of the way PCB's are manufactured, in wave soldering machines in which all components are populated onto the board and then the entire board is run through the wave soldering bath - and the Resist, usually green in color but not always - prevents the solder from adhering to the entire board traces, but only to the areas where there is no Resist. 

3) The board could last many decades before corrosion would be problematic where the Resist is removed like you describe. 

4)  If it absolutely bothers you, the fingernail polish is as good as anything else, maybe clear fingernail polish would look nicer'n red, 'k? 

*CONFORMAL COATING* is what we use to protect printed circuit boards from harsh environment such as salt water or extreme high humidity or corrosive environments, which the average home and hamshack does not ever see.  This is a clear coat that comes in spray cans and is obtainable from well-stocked Electronics Supply outfits.  In use, the entire board, components, solder joints and all, both sides, is sprayed with the clear conformal coating.  You don't need it on the stuff in the hamshack, not one little bit.  Besides, it ain't cheap like spray paint, which it isn't.  And it can make repair and rework a bit tricky. 

Worry not about the scratch in your board's Solder Resist. 


73
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KU4UV
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Posts: 376




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« Reply #2 on: June 03, 2011, 07:45:54 PM »

Thanks much! Smiley

73,
KU4UV
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WB6BYU
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Posts: 13243




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« Reply #3 on: June 03, 2011, 09:00:26 PM »

Quote from: KE3WD

*CONFORMAL COATING* is what we use to protect printed circuit boards from harsh environment such as salt water or extreme high humidity or corrosive environments, which the average home and hamshack does not ever see...

In the older equipment it was called MFP (Moisture and Fungus Proofing).  Made a lot of old military gear
a real adventure to work on.



But don't worry about a bit of copper.  Many of the older circuit boards didn't have any cover over the
copper traces and they still work 20 to 30 years later.
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AA4HA
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Posts: 1434




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« Reply #4 on: June 10, 2011, 08:28:55 AM »

Fingernail polish works fine. Go with a clear coating. Some of the colors have metallic flake in them.

Tisha Hayes, AA4HA
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
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