Peter Todd wrote:
> Unfortunately in this case the device is going to be battery powered,
> so heaters are totally out, well, almost, plutonium powered heaters
> would last long enough... :)

What's your budget?  :)

> A conformal coating wouldn't work in my case as I have a display, and I
> don't want condensation between the display and the (acrylic) walls of
> the box. 

Seems like you have two potentially separable issues, then - 
condensation causing electrical shorts on the board, and condensation 
getting in the way of the display.

Can you bond the display flush to the box wall with some clear adhesive? 
  Or cast the display face in resin to make a piece that could bond 
flush with the display wall?  Then you could conformal coat the rest of it.
-- 
Timothy J. Weber
http://timothyweber.org
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