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conformal coating

Discussion in 'Electronic Components' started by RHRRC, Mar 7, 2009.

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  1. RHRRC

    RHRRC Guest

    I need a conformal coating that will protect a pcb in a saline
    atmosphere, maybe even the odd small drop of saline will land on the
    pcb.
    The temperature is room temp and the pcb dissipates only the odd mW
    (no hot components)

    Potting is not an option but dipping is!! (odd I know but
    nevertheless)

    Has ayone knowledge/experience of a suitable conformal coating?

    Thanks
     
  2. MooseFET

    MooseFET Guest

    How long do you need it to work for. A coating just slows the
    progress of the salt and water working its way towards the PCB.
    Potting is thicker so it works longer.
    Put it in a sealed housing and drop the coating?
    Does it travel to the destination by air? Does it get exposed to sun
    light.

    I have lots and lots of experience of unsuitable ones. I gave up long
    ago and went the sealed housing route.
     

  3. Dolph's

    http://www.dolphs.com/pdfs/DOL_spraychart.pdf

    The AC-41 is the stuff you want.

    These are aerosols. They also have it in 1 Gal pails or bigger as well.
     

  4. Name one modern electronic conformal coating that is attacked by normal
    saline solution.

    What a total bullshit declaration.
     

  5. Jeez what a stupid remark.

    He is looking for someone with favorable experience, not some dopey ****
    that gave up along the way.
     
  6. Nico Coesel

    Nico Coesel Guest

    The problem is not the coating, but there are always wires going
    towards a PCB. This is where most of the water creeps in. Even regular
    chips have this problem. Thats why chips need to be baked if they
    where stored in open air for more than a few hours. Otherwise the
    packages will split open due to boiling water.
     

  7. Apples and oranges. Water contained in parts has nothing to do with a
    sealed assembly being attacked externally by moisture.

    Of course the proper sealing method would be to bake the assembly and
    or apply vacuum to the assembly to remove ALL water from it BEFORE
    applying the coating.
     
  8. Guest

    I have experience with 3. Here they are, in order of effectiveness,
    most effective first:
    Parylene (Excellent)
    .. Excellent performance, but requires expensive equipment to
    apply.
    .. Can not be dipped or brushed.
    .. There are companies that will coat boards using Parylene.
    Resiweld
    .. Can be dipped or brushed.
    Humiseal
    .. The worst of the bunch, but OK for repair of small areas.
    Regards,
    Jon
     

  9. 'Worst of the bunch'? YOU are the worst of the bunch.
     
  10. MooseFET

    MooseFET Guest

    Name one that doesn't eventually let the saline through.
     
  11. MooseFET

    MooseFET Guest

    This looks like another nym for Always Wrong. He seems to be
    supporting the idea that a coating will work.
     
  12. MooseFET

    MooseFET Guest

    I am fairly certain that the AC-46 from these guys is one of the ones
    I tried. It worked about the same as the others. ie: it failed to
    keep the salt out of the PCB.
     
  13. MooseFET

    MooseFET Guest

    We had it done by an outside company. It was about the best of the
    ones I tried.
    I have used one that can be brushed. Brushing without making bubbles
    is a bit tricky. It is better to put multiple coats than to try to do
    it all in one go.

    Where I work, we called Humiseal "circuit stop". It was worse than an
    unsprayed PCB.
     
  14. Can you really be *that* stupid?
     

  15. You're a goddamned idiot. OF COURSE it would work!
     

  16. You are devoid of facts, ie therefore full of shit.

    What you know about coatings would fit on the tip of a molecular probe.
     

  17. Ever heard of reduced pressure, or a fucking vacuum, you retarded, know
    nothing ****?
     
  18. MooseFET

    MooseFET Guest

    Yup it must be Dim Bulb AKA Always Wrong.
     

  19. Yeah. I'm the guy that knows more about coatings and potting media than
    a punk, pussy twit like you ever will.
     
  20. Nico Coesel

    Nico Coesel Guest

    A part is also a sealed assembly! So if a small sealed assembly can't
    keep the water out, a big one can't either. Ofcourse you can use
    better materials which slow down the ingress of moisture but
    eventually you'll have moisture inside.
    That is standard procedure. Still, relying on the sealing is relying
    on false hope. Water molecules are fairly small so they can creep into
    very tiny openings.
     
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