Re: gEDA-user: OT: UV exposure?

[Dan McMahill <dan@xxxxxxxxxxxx>]

DJ Delorie wrote:
> I was thinking... epoxy coat the whole board (except your sensors).
> Then, put a second coat on and press a layer of aluminum foil into it
> (with suitable cutouts).  Then a third coat on the outside of the
> foil.
>
> Overkill, perhaps, but it should block all light and chemicals.

hmmm...  I'd be happier if the metal shield were grounded.  Obviously it 
depends on the exact circuit, but this could lead to some interesting 
coupling.  Shouldn't be too hard to calculate for a few cases.  Watch 
out for op-amp summing nodes, thats one place where you can easily 
couple in things.  Reminds me of a 4-layer board I saw once that had the 
ground and power planes swapped internally ( top, VDD, GND, bot instead 
of top, GND, VDD, bot) and the VDD plane ended up acting as the path for 
some unwanted signal coupling.

Neat idea though.

-Dan
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