gEDA-user: OT: UV exposure?

[Mike Hansen]

Most glass products block deep UV rays, you actually have to spend quite a 
bit of money if you want to use glass that will pass 350nm and below.  And 
most clear acrylics will block UV(again,you can get UV passing plastics but 
they cost $$$).   Glass has the advantage over plastic in that UV exposure 
will smash the bonds in the plastic and cause it to craze, this is what you 
see on older plastic car parts where it looks like the color has bled out of 
them or in clear acrylics the plastic almost appears to have shattered w/o 
breaking apart.  So if you want a window that holds up over time I suggest 
going with glass(and no boro float glass, that passes UV).

I might suggest only putting a window on the areas that require 
illumination.  Cover everything else up. UV is nasty and it's energy is 
great for smashing the bonds of just about any material, plastics or 
DNA(skin cancer anyone?).


>From: Dave McGuire <mcguire at neurotica.com>
>Reply-To: gEDA user mailing list <geda-user at moria.seul.org>
>To: geda-user at seul.org
>Subject: gEDA-user: OT: UV exposure?
>Date: Tue, 27 Jun 2006 02:21:16 -0400
>
>
>   Hey folks.  I'm working on a design which will live in direct sunlight.  
>It will be under glass and I can seal the chassis, so there won't be any 
>moisture issues, but the PCB will be exposed to sunlight every day.
>
>   Does anyone know if I'm going to have problems with the UV breaking down 
>the PCB material?  If so, is there some sort of coating that I could put on 
>the board to mitigate this?
>
>           Thanks,
>            -Dave
>
>--
>Dave McGuire
>Cape Coral, FL
>
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