I guess I missed my point (pun intended). I was referring to making a good contact through the paint, a non-insulator, or assuming that a good contact was make, whether a sharp point or dull point or bent point is used. If the "proper" galvanic contact is not made, the scope I mentioned will display a waveform that can be used to notice this during testing the numerous locations. Calibration is another issue altogether. ps. what is calibrated on an ESD gun anyway? The ones I've had are verfied to perform as designed, or they are broken.
- Bill Indecision may or may not be the problem. --- On Fri, 5/29/09, Steve O'Steen <[email protected]> wrote: From: Steve O'Steen <[email protected]> Subject: RE: [PSES] ESD testing To: "Bill Owsley" <[email protected]>, [email protected], "John Woodgate" <[email protected]> Date: Friday, May 29, 2009, 1:39 PM Bill, I’ve conducted a similar experiment using the IEC 61000-4-2 target and have noted deviations in the discharge waveform between a sharp tip, dulled tip and bent tip. Unfortunately, if you try to scrape the paint away with the end of the tip, it can be deformed. There are a multitude of variables that could affect the recorded waveform, too many to mention, so I think an effort to control as many of these variables as possible just makes good sense. Preserving the shape of the discharge tip eliminates one of those variables. Regards, Steve O'Steen Director, EMC Advanced Compliance Solutions, Inc. [email protected] <http://us.mc01g.mail.yahoo.com/mc/[email protected]> 770-831-8048 ext. 210 www.acstestlab.com <http://www.acstestlab.com/> ****************CONFIDENTIAL**************** This e-mail and any attachments may contain information which is confidential, proprietary, privileged or otherwise protected by law. The information is solely intended for the named addressee (or a person responsible for delivering it to the addressee). If you are not the intended recipient of this message, you are not authorized to read, print, retain, copy or disseminate this message or any part of it. If you have received this e-mail in error, please notify the sender immediately by return e-mail and delete it from your computer. ________________________________ From: [email protected] [mailto:[email protected]] On Behalf Of Bill Owsley Sent: Friday, May 29, 2009 12:18 PM To: [email protected]; John Woodgate Subject: Re: [PSES] ESD testing We've used an old o'scope to monitor the ESD event. Set it up nearby with a bit of wire for an antenna attached to a channel, adjust to trigger on the ESD event, and watch the waveform. A good contact discharge makes one kind of waveform and nearly good contact makes noticeably different waveform. - Bill Indecision may or may not be the problem. --- On Fri, 5/29/09, John Woodgate <[email protected]> wrote: From: John Woodgate <[email protected]> Subject: Re: [PSES] ESD testing To: [email protected] List-Post: [email protected] List-Post: [email protected] List-Post: [email protected] Date: Friday, May 29, 2009, 11:19 AM In message <[email protected] <http://us.mc01g.mail.yahoo.com/mc/compose?to=0ed66cd2c9bd0a459d54fb9119a60567f4a...@mailserver.lecotc.com> >, dated Fri, 29 May 2009, "Kunde, Brian" <[email protected] <http://us.mc01g.mail.yahoo.com/mc/[email protected]> > writes: > Is that true? Has anyone done tests to see the difference of the ESD pulse > with a brand new sharp ESD Gun TIP vs a warn-out TIP that is no longer sharp? > I would think that as long as you make good contact with the metal that the > sharpness of the tip would have no or little affect on repeatability. Yes, 'as long as'. It's not easy to be sure that a non-conducting layer has been fully penetrated, so a sufficiently dull tip may give optimistic results. > > One last question. The TIPs on our ESD gun are made out of Brass and dull > very quickly. They are very costly from the manufacturer so our machine shop > has been making us new ones out of the same base material. However, because > they dull so quickly I would like to have them made out of a harder material, > such as Stainless Steel. Has anyone found that changing the tip material > affects the repeatability of the ESD test? Figure 3 of IEC 6000-4-2 does not specify the material of the tip. It doesn't even say that it must be conducting! (It actually says that there may be an insulating covering, but I guess it doesn't mean over the sharp point!) I can't see any reason why a hard metal tip should not be used. The hard (austenitic) variety of stainless steel, however, is naturally hard to work. Depending on the machining required, something else might be better. I can't see why the tip has to be 12 mm diameter. Since it is, the body could be a low-cost material, such as alumin(i)um, with a much smaller, interchangeable sharp point embedded. Has anyone got a store of phonograph/gramophone needles? No, not thorn ones, or diamond-tipped! -- OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk Things can always get better. But that's not the only option. John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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To post a message to the list, send your e-mail to <[email protected] <http://us.mc01g.mail.yahoo.com/mc/[email protected]> > All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. 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Website: http://www.ieee-pses.org/ Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher <[email protected]> David Heald <[email protected]> - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at http://www.ieeecommunities.org/emc-pstc Graphics (in well-used formats), large files, etc. can be posted to that URL. 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