[time-nuts] wwvb weak on east coast especially when the pre-amps under wa...

Arnold Tibus arnold.tibus at gmx.de
Tue May 15 09:59:15 UTC 2012


>> What type of coating do you recommend? What is the downside of coating all electronics?
> As i wrote before, we usually use "Plastik 70" and "Urethan 71" for the
> stuff that does not need high specs. For those that are under water and/or
> more aggresive stuff (like body fluids) we use parylene.
More or less the same product as Plastik 70 (spray) is Acrylic Conformal
coating
from Ambersil which is perhaps better known in other countries. Both
companies
belong to CRC.com.
Both coatings are low viscosity, solvent-drying, acrylic based conformal
coatings with
excellent insulating properties (diel. strength >80kV/mm), developed
specially to
protect pc-boards.
> The down side is that it costs money (it needs a manual step) and it makes
> reworks more difficult as you have to ensure that after the rework the
> coating is made watertight again (which isn't as easy as it looks).
>
> Oh.. and connectors are really a pain with any coating. Either you
> coat them as well and lose the connectivity or you have a point where
> water can creep under the coating.
>
If I remember well there is no water creeping under these acrylic
coatings at normal
conditions and they remain somewhat eleastic. For repair works at least
PLASTIK 70
can be soldered through or be totally removed with acetone.

Urethane is a very good coating but can only be removed by abrasion/
scratching.

The product information sheets I found here:
http://www.crcind.com/wwwcrc/tds/TKC3%20PLASTIK70.PDF
http://www.crcind.com/wwwcrc/tds/TAI3%20CONFC.PDF

Don't forget to read the safety information sheets which are as well
available
from the manufacturer.

regards
Arnold






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