[sdiy] (no subject)

[David Anderson]

Epoxy potting is very common these days but it all depends on the epoxy 
you use. You'll want something with low shrinkage, which is what 
potting/encapsulating epoxies are made for.

Given your application, you probably want to use something like Durapot 
865, MG Chemicals 832TC or Robnor PX439n. All are potting compounds that 
are thermally conductive and dielectric. MG Chemicals 832TC is available 
from Mouser. Robnor PX439n is available from Rapid.

http://www.mouser.com/ProductDetail/MG-Chemicals/832TC-450ML/?qs=nnh8%2fA0SuH%2fLBKx%2fKG5%2fkw%3d%3d

http://www.rapidonline.com/Tools-Equipment/Thermal-Conductive-Epoxy-Resin-Px439n-250g-87-0222

David

On 11/29/2011 7:25 AM, Needham, Alan wrote:
> I have recently decided to use some SMT tempcos with wire tails in lieu
> of 'proper' through-hole resistors on VCOs.
>
> Some of the SDIY gang have used epoxy resin to encapsulate SMTs in this
> sort of application to provide some physical strength, is there any
> evidence of the set epoxy changing the component properties? Has anybody
> actually checked?
>
> I ask this because decades ago, I read about a tiny radio transmitter
> working fine until epoxy encapsulated and the fault being blamed on the
> resin 'crushing' the components as it cured and altering the tuning, I
> cannot remember if the faultfinding revealed if it was caps, coils, or
> whatever and I am only interested in the tempco here so it could be
> irrelevant.
>
> Any thoughts on this?
> Thanks.
>