Jhon wrote:
>
> I would like to know if there is anybody has had any experience in
> designing ESD/EMI compliant hardware/software, and whether you would be
> willing to share some of your experiences with meeting the
> 801-2 requirements for electromagnetic compatibility
>
> Thanks in advaced
The first rule is to ground everything that is a metal surface
accessible to the ESD gun solidly to chassis ground (metal to metal).
Masking may be necessary for painted covers. In some instances
you may need to use toothed star washers.
Second is to ground cables and shields to cables at the point
of entry to your product. In other words, as soon as you can.
You may experience two phenomena (little understood) that mean
two entirely different things:
1. Your product fails at a minimum level, say 4KV and
continues to fail at any higher value. This is
USUALLY a grounding issue.
2. Your product fails within a band of voltage, say
4KV to 6KV, but operates below AND above these limits.
This is a more complicated reaction of your system
to the different spectral content of of the pulse
within the band 4KV-6KV then outside it.
This is usually a system frequency response issue
that can be very difficult to pinpoint and usually
results in alot of grounding effort that proves
useless. For instance, there could be a slot
antenna formed between the cover and the case
that 'activates' in the KV range as a tremendous
transmitter when current circulates around it
on its way to ground.
Anyway, keep a close eye on the results of where the spark
is being applied to the product and system ground. The current
will circulate through your product to that ground point
and unfortunately through anything in between if there isn't
a good ground.
*******************************************************
Doug McKean
doug_mckean@paragon-networks.com
-------------------------------------------------------
The comments and opinions stated herein are mine alone,
and do not reflect those of my employer.
-------------------------------------------------------
*******************************************************
Date: Thu, 07 Nov 1996 14:26:41 -0500
Original Subject: Re: ESD ZAPPPPPP ZAPPPPPPPP