Re: [SI-LIST] : ESD Gun

Doug Smith (dsmith@corp.auspex.com)
Mon, 09 Aug 1999 10:00:12 -0700

At 03:34 PM 8/3/99 -0700, you wrote:

>Can anybody suggest a best ESD Gun to generate the ESD pulses to test
>the
>ESD susceptibility of Digital Boards? We have looked into "ets" from
>Electro-Tech Systems Inc. and MINIZAP from KeyTek.
>
>Any suggestions / comments?
>
>Regards,
>
>Manix Velu.
>

Hi Manix,

I am posting this to all as there may be some general interest in my reply.
I am going to assume you mean testing boards for immunity with respect to
upset as opposed to damage. If you are talking about damage, that is a
Pandora's Box of issues. Although there have been many attempts to come up
with a method for testing boards for damage immunity from ESD, BellCore has
one as well as some private companies, there is not agreement on the
method. Of the methods I am familiar with, I don't consider any to be
adequate. It is possible to pass the test with a bad board design and
vice-versa. On the upset immunity front.....

I have used the Mini-Zap for years and am very happy with it.

One of the problems with the current IEC 61000-4-2 standard is that the
waveform is not very well characterized. There are some ESD guns on the
market that have lots of high frequency ringing on their waveforms (above 1
GHz) that can affect equipment but does not prevent passing the
requirements of 61000-4-2.

I have measured the Mini-Zap as part of my work with ESD WG14.0 standards
work several years ago. When measured with much higher bandwidth than
required, its waveform is still close to the picture in 61000-4-2.

Another affect is EM radiation directly from the gun. I have not measured
the Mini-Zap myself. But this parameter is not specified at all in the
standard so it is just a shot in the dark.

There are lots of stories of equipment passing with one brand of simulator
and failing with another. This is just an indication of the lack of
adequate simulator specs in 61000-4-2. In all fairness, when -4-2 was
written, the high bandwidth scopes we have now were not readily available
and the standard had to be written to use available test equipment.

Another characteristic of the Mini-Zap that I like: I travel quite a bit
with the Mini-Zap and appreciate that its profile on an airport X-Ray does
not look like a "gun" as some do. :-) When asked what it is by the airport
security people it becomes and ESD "simulator" as opposed to an ESD "gun".
This is followed by a (hopefully) short discussion on what "ESD" is.

Doug

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