The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: Joseph Legris
X-Mailer: Mozilla 4.77 [en]C-SYMPA (Win95; U)
Subject: Re: Side effects of potting compound !
Date: Sat, 02 Nov 2002 11:15:14 -0500
NNTP-Posting-Date: Sat, 02 Nov 2002 11:15:25 EST
Organization: Bell Sympatico
Bob Wilson wrote:
> In article <email@example.com>,
> firstname.lastname@example.org says...
> >"Tom Del Rosso" email@example.com wrote:
> >>"Gibbo" wrote in
> >>message news:firstname.lastname@example.org...
> >>> The square ones with a circular element and worm drive. Beats me how
> >>the hell
> >>> it's doing it. All three have moved by roughly the same amount (within
> >>a few
> >>> percent).
> >>> Can't leave it exposed as it'd buried really deep next to some high
> >>> components.
> >>If you did the conformal coating after gluing it with nail polish, then
> >>you could be really confident of it.
> >>It would be neat to have a trimmer remain exposed through a tunnel,
> >>especially if the screw is on top. I'm thinking of a piece of tubing
> >>wide enough to surround the whole trimmer, a little silicone squirted on
> >>the board around the base of the trimmer, and the tube placed over the
> >>trimmer before potting. Just a thought since you don't need it exposed.
> >Yeah that would be the ideal but the time meddling with it kinda kills the
> >Tomorrow is truth day. I did 2 more today. Calibrated them then covered the
> >entire preset with 2 part silicon sealer. Then potted them in polyeurethane
> >(instead of epoxy). If that fails then they're having them unpotted. I'm
> >starting to get bored of it now !
> This may be somewhat pointless. Silicone is completely incompressible. While
> it may SEEM soft and rubbery to the touch, this is only because it DISPLACES
> when you compress one part of it. While this may be great for locally
> applied pressure when unpotted, once it is entirely encapsulated by a
> rock-hard potting compound, there is nowhere for the material to displace
> when presure is applied. Thus, once potted, silicone is effectively as hard
> as a rock.
But it can still flow a little within the fixed volume.
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup