At 08:27 1998-01-30 PST, you wrote:
>Hi Guys
>
>Just doing a little thinking here and I was wondering what my options
>are to protect circuitry from the elements.  I was thinking of encassing
>the whole controller (PIC, crystal, regulator, adc, etc..) in epoxy to
>protect it from rain, snow, etc...  I'm just curious if this would cause
>the components to overheat and eventually breakdown. Please, if you have
>experience with this sorta thing let me know what you've tried and whats
>been succesfull.
>
>Thank you
>
>Charles

I am casting a little regulator in epoxy. 3k units so far.
The manufacturer can tell you the heat transfer properties.
I use a epoxi with 70% quartz powder (not sure of the english name is correct)
for many reasons: Better heat transfer, lower price per volume, more
environmental (less plastic), and a heat elongation more in correlation
with the glass reinforced PCB.

There are lots of brands and types of epoxy.

Thera are also lot of other plastics to cast in.

Another idea is to cast in silicone rubber. Thermal transfer vary. This is
highly flexible and will not cause mechanic stress on components caused by
thermal etc.

For outdoor or marine (I think) use the best is som e kins of very flexible
sticky silica gel. It will heal itself if you by example stick a needle in
it. It will also guarenteed stick to whatever is coming out or into your
PCB (cables, connecting rods...) so no water will find its way in. Other
material above may by time and wear crack in theese cases and let water in
along cables. You cant use It alone; you have to cast it in a pot or
something.

The silicone and silica gel is removable for testing and repair/upgrade
purposes. Both also come in transparent versions.

/Morgan
Morgan Olsson, MORGANS REGLERTEKNIK, Sweden, ph: +46 (0)414 70741; fax 70331
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