From: Mike Monett
X-Mailer: Mozilla 2.02 (Win16; I)
Subject: Re: Low leakage parts
References: <firstname.lastname@example.org> <email@example.com>
Date: Sat, 04 Jan 2003 11:32:53 -0800
NNTP-Posting-Date: Sat, 04 Jan 2003 11:32:53 EST
Organization: Bell Sympatico
Winfield Hill wrote:
> While impressive that's not unreasonable, and it demonstrates
> that under good conditions both air and semiconductor plastics
> have much better insulation capabilities than some would think.
> - Win
Just to put some numbers on it, here's snips from Bob Pease:
"What's All This Femtoampere Stuff, Anyhow?"
"The other material we like to use for an insulator is the body of
the plastic-DIP ICs. This has an impedance up near 10^16 ohms, which
is about as good as you need."
"Ceramic DIP packages, on the other hand, aren't nearly as low in
leakage, more like 10^14 ohms - not very good for precision work at
Here's an interesting comment on reed relays:
"The interesting point is, that some standard, cheap and small
plastic dil reed relais by Siemens had a typical insulation
resistance of nearly 10 exp16 Ohms. Of course you could not put them
into the board, you had to wire the 'hot' contact directly and use
all the techniques described in Mr. Pease articles. But the relays
where damn good and we used them in some hundred devices. Maybe
their packages where made out of an equal low leakage material like
the LMC types or the BurrBrown INA116. The problem is, after six
years, they changed their packaging material and the wonder-relais
turned into ordinary ones with 10exp (12) or worse."