Ingemar and Ramon,
If you soak most polymers in alcohol, you are likely to have a detrimental
affect on the coating.
Coatings are NOT impervious they breathe. If you have any ionics under a
coating and you expose them to high levels of humidity then you will
initiate osmosis. This would certainly cause blistering to the coating and
nasty conductive growths under the coating.
Acrylics have been widely used in avionics applications because they are the
easiest to repair. We have seen assemblies under test actually running with
condensation to simulate take-off and landing and the acrylic performed
better than others.
--
Regards Graham Naisbitt
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On 2/2/05 2:20 pm, "Dehoyos, Ramon" <[log in to unmask]> wrote:
> Hi Ingemar:
> Do you want to see a board that the coating has potato
> chipped? I do not have anyone at the moment, but it is easy to do. Get a
> scrap board that is coated with polyurethane or Acrylic, soak it in alcohol
> for about five minutes. Place the soaked board in a sealed container. Leave it
> there 24 hours or so. The board coating will be very soft and in some areas
> will look like potato chips.
> Regards,
> Ramon
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Ingemar Hernefjord
> (KC/EMW)
> Sent: Wednesday, February 02, 2005 3:17 AM
> To: [log in to unmask]
> Subject: Re: [TN] Coating
>
>
> Sure? That was a very frightening message! Do you have example? Can you send
> pic offline?
> We've made a lot of boards for various aircrafts, with acrylic, never seen or
> heard of what you say.
>
> Acrylic coating does not always withstand stillstanding contaminated water.
> Exposed a longer time to such
> ionic wetness, the coating can absorb water, swell, and lift from the board.
> We don't know exactly how this
> happens, and have just seen a few cases. Acrylic coating use to be splendid.
> Ingemar Hernefjord
> Ericsson Microwave Systems
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]
> Sent: den 1 februari 2005 18:30
> To: [log in to unmask]
> Subject: [TN] Coating
>
>
>
>
>
>
>
> All Technetters :
>
> In advance, thanks for your insights. Does anybody have any experience
> with boards that are acrylic coated and exposed to Jet fuel fumes.? Boards
> are not located next to the jets, but the fumes propagate to the boards that
> are housed in a metal cabinet. My understanding is that jet fuel is similar to
> kerosene. Through experimentation, I know that alcohol fumes that are inside
> a close container with the a board , can weaken acrylic and polyurethane
> coating and sometimes the coating will potato chip.
>
> Regards,
> Ramon
>
>
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