But crossing t's and dotting i's is exactly what is required by
competence standards, including the several ISO 170XX series.
Furthermore, standards specify performance of test equipment, if
possible, and only if that is not possible, they specify design. If that
is not possible, they specify construction, and indeed many CISPR and
other standards specify test set-ups with elaborate drawings.
EMC testing is DIFFICULT. It does involve extensive experience and it is
costly. Management systems are/should be in place to catch errors. Daily
and weekly verifications are required. In many cases, running tests on a
known sample are OK, but that's dodgy for ESD, because repeated testing
WILL cause damage.
On 2023-08-12 03:25, Ken Javor wrote:
No way am I jumping in the middle of this debate, but it is extremely
useful in another way.
A few observations:
ESD is by its very nature a chaotic event (air discharge more so than
contact).
It is not entirely surprising that someone who has spent decades
working on something would find examples of non-idealities in the work
of technicians doing rote work following canned test procedures. A
test facility isn’t going to make a profit employing a septuagenarian
devoted to crossing every “t” and dotting every “i.” (Written by
someone pushing that age bracket pretty hard).
IFF (if and only if) Mr. Smith’s observations are correct, that is an
indictment of the test requirement/method. That is, it is the
responsibility of the standards committees to write these such that
they can be adequately performed by the average test facility and
personnel. If it takes someone with five decades of experience, and
they must spend an inordinate amount of time ($$$) to get it right,
then the standard is a failure.
--
Ken Javor
(256) 650-5261
*From: *"doug emcesd.com" <[email protected]>
*Reply-To: *"doug emcesd.com" <[email protected]>
*Date: *Friday, August 11, 2023 at 11:26 AM
*To: *<[email protected]>
*Subject: *Re: [PSES] thoughts on ESD test lab problems
I didn’t say most labs are bad. Errors do happen and for me
almost every lab I have used has made a mistake. These errors are rare
but do happen and the effect of a single error can be very costly.
One lab made an especially bad mistake for a small company that
engaged me that cost the company a lot of money, has since improved
their game by instituting quality procedures they should have had
anyway. The lab gave the company passing data but in fact the plot
looked like the technician forgot to plug the antenna in, noise level
of the instrumentation!
Based on that, the company signed a contract for price and delivery
for a million units of their product. The ultimate fix needed was a
different core design of an inductor that cost them US $0.30. $300k is
a lot of money for a small company.
I can give many more examples. Usually the problem causes a product to
fail when it actually should have passed. I have many examples that
happened to me over the last 40 years in both private and commercial labs.
The errors are still rare, but do happen. Over enough testing a
person, like myself, will encounter an error with any given lab.
Of the errors I have encountered, three were the result of the staff
in the lab not being competent (over a span of 40 years), the rest
were just simple mistakes, maybe another dozen or so. Again, this was
over decades, so rare, but many millions of dollars were at stake in
each case.
In two cases, the lab personnel became a bit belligerent when I gently
suggested they performed the test incorrectly. In both cases, the labs
relented and retested after we examined the test standard and they
realized they were testing incorrectly.
A lab client needs to keep an eye out to make sure such an error
does not happen to them.
On the other hand, I have seen a lot of great labs. One, in Silicon
Valley, I consider to be the best in the industry! But they did make
one mistake on a test for me years ago, minimal impact at the time and
it can't happen again.
Doug Smith
Sent from my iPhone
IPhone: 408-858-4528
Office: 702-570-6108
Email: [email protected]
Website: http://dsmith.org
------------------------------------------------------------------------
*From:* John Woodgate <[email protected]>
*Sent:* Friday, August 11, 2023 07:02
*To:* [email protected] <[email protected]>
*Subject:* Re: [PSES] thoughts on ESD test lab problems
That's right. It is good to call attention to problems that may well
be deeply hidden or not recognized as a possibility, but it is
necessary to concentrate on the facts and leave out peripheral matters
that don't help to deal with the issue.
On 2023-08-11 14:28, Larry K. Stillings wrote:
You could certainly word this in a different way that doesn’t
generalize how “most” test labs are bad and/or incompetent. How
about in the future you find a different way to word things.
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