Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

----- Original Message -----
From: "Steve" <alienrelics@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, December 01, 2003 11:29 PM
Subject: [Homebrew_PCBs] Low leakage coatings? Re: how can i prevent
corosion?


> --- In Homebrew_PCBs@yahoogroups.com, "Leon Heller" <leon_heller@h...>
> wrote:
> >
> > ----- Original Message -----
> > From: "Steve" <alienrelics@y...>
> > To: <Homebrew_PCBs@yahoogroups.com>
> > Sent: Monday, December 01, 2003 6:28 PM
> > Subject: [Homebrew_PCBs] Low leakage coatings? Re: how can i prevent
> > corosion?
> >
> >
> > > Does anyone here have experience and suggestions for low-leakage
> > > coatings? I've got some circuits in mind that in the past I've done
> > > dead-bug style to avoid surface leakage on a PCB. Is there a good not
> > > to expensive low leakage coating?
> > >
> > > I'm thinking of an input with an impedance in the rage of 100M to 10G.
>
> >
> > Have you used 'guard ring' techniques and Teflon standoffs?
> >
>
> That blocks interference but it can actually make leakage worse as the
> path to ground is shorter.
>
> No, haven't tried Teflon. Is it that good an insulator? What am I
> using the stand-offs for? If you mean the supports for the PCB, that
> still leaves me with surface leakage across the PCB.

The technique I was thinking of was to bend up the input pin and solder it
to a Teflon standoff. Teflon is a very good insulator. This is sometimes
done if a very high input impedance is required.

Leon
--
Leon Heller, G1HSM
Email: aqzf13@...
http://www.geocities.com/leon_heller