To clarify a little, one brand has this field, a very large field, when the switch closes. The other brand does not. This happens before the intended approach to smack the victim. And it happens again after the intended discharge, when the switch is released to the open position. Details for detecting these fields is left as an exercise for the curious. It is quite simple, and very illuminating! 8-) Calibrations must be a challenge since closing the switch is likely to trigger the 'scope, as well as opening the switch. We use 2 people - one operating the gun, one operating the 'scope, so we can capture the waveform.
Bill In the event of a national emergency, click on the following links to provide directions to your duly elected mis-representatives.http://www.usa.gov/Contact/Elected.shtml or... https://writerep.house.gov/writerep/welcome.shtml http://www.senate.gov/general/contact_information/senators_cfm.cfmif really desperate... http://www.usa.gov/Contact/Elected.shtml --- On Fri, 12/10/10, Pommerenke, David <[email protected]> wrote: From: Pommerenke, David <[email protected]> Subject: RE: [SI-LIST] Re: variations in ESD simulators To: "Bill Owsley" <[email protected]>, "Douglas Smith" <[email protected]>, "emc-pstc" <[email protected]>, "Si-List" <[email protected]>, "Ram Chundru" <[email protected]> List-Post: [email protected] Date: Friday, December 10, 2010, 10:11 AM Group, All ESD generators use a high voltage relay for the contact mode ESD. This relay is closed for air discharge testing. It is pretty common for ESD generators to cause a small, but fast rising transient field pulse when the relay closes for the purpose of air discharge. Some avoid this by using two relays or other methods. Those pulses can be measured quite easily. Of course, these pulses are not what the ESD test standard (IEC 61000-4-2) intended. However, pulses of that nature can happen in reality quite easily. For example, if two smaller metal parts meet at low humidity you may see 100ps rise time pulses. If your DUT is sensitive to these pulses, and it is used in an environment at which those pulses can occur, then it might be a good idea to identify the root cause of the problem to fix it. Finding the root cause of ESD upset problems is not so difficult. Susceptibility near field scanning is typically used to identify the root cause of ESD upset problems. For further reference or information check "Muchaidze et.al., Susceptibility Scanning as a Failure Analysis Tool for System-Level Electrostatic Discharge (ESD) Problems, IEEE Transactions EMC, May 2008 50/2" or contact me directly. Regards, Dr. David Pommerenke Missouri University of Science and Technology (MST), former name: UMR 118 EECH, 301 W. 16th Street, Rolla, MO 65409-0040 573 341 4531, cell: 573 308 2019 -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Bill Owsley Sent: Friday, December 10, 2010 12:28 AM To: Douglas Smith; emc-pstc; Si-List; Ram Chundru Subject: [SI-LIST] Re: variations in ESD simulators We have an ESD gun that for air discharge, when the trigger is pulled, will broadcast a field that is known to us to cause most of our anomalies. Same happens when the trigger is released after the actual air discharge to the intended target. We have a name for this gun, but decency, what little I have, keep me from repeating it ... ps. two cal labs and the manufacturer, even when told what to look for and how to see it, say it is just fine, no problems, it works as intended. So it appears that outside of the defined performance, any performance is allowed ?!?!?! Bill In the event of a national emergency, click on the following links to provide directions to your duly elected mis-representatives.http://www.usa.gov/Contact/Elected.shtml or... https://writerep.house.gov/writerep/welcome.shtml http://www.senate.gov/general/contact_information/senators_cfm.cfmif really desperate... http://www.usa.gov/Contact/Elected.shtml --- On Thu, 12/9/10, Ram Chundru <[email protected]> wrote: From: Ram Chundru <[email protected]> Subject: Re: [SI-LIST] variations in ESD simulators To: "Douglas Smith" <[email protected]>, "emc-pstc" <[email protected]>, "Si-List" <[email protected]> List-Post: [email protected] Date: Thursday, December 9, 2010, 8:46 PM Hi Doug,The IEC 61000-4-2 standard is a loosely defined spec. It only specifies a few parameters for the discharge current and with pretty big tolerances (peak current has +/-10% tolerance, rise time has a range from 0.7 ns - 1 ns and current at 30 ns and 60 ns have +/-30% tolerance). Consequently it is possible for all the commercially available ESD generators to meet the specifications but still produce vastly different discharge current pulses. For example, one generator might produce a slowly falling first hump and another generator might produce a rapidly falling first hump as the fall time is not specified in the standard. This results in big differences in current derivatives (didt) which in turn results in big differences in the fields coupled by the two ESD generators to the EUT. The standard does not specify the transient fields generated by the ESD generators which are a combination of fields caused by the discharge current at the tip of the generators and the fields caused by the faster currents inside the ESD gun bodies. This variation in fields among ESD generators is a bigger contributor to the un-reproducibility of test results (soft failures) than the variations in the discharge currents (hard failures) since the current is somewhat regulated by the spec but not the fields. Thanks, RamEMC EngineerApple Inc. From: Douglas Smith <[email protected]> To: emc-pstc <[email protected]>; Si-List <[email protected]> Sent: Wed, December 8, 2010 9:45:25 PM Subject: [SI-LIST] variations in ESD simulators Hi All, My latest monthly article is out! Technical Tidbit - December 2010 Comparing "IEC 61000-4-2 Compliant" ESD Simulators Abstract: IEC 61000-4-2 compliant ESD Simulators (150 pF/330 Ohm network) arerequired to meet a specified waveform. Results are presented here comparing the current waveforms delivered into a metal tabletop (Horizontal Coupling Plane of IEC 61000-4-2) by three different simulators. The results were not as uniform as expected. The data presented has implications for the reproducibility of ESD testing. The link to the article is: http://emcesd.com/tt2010/tt120210.htm[1] Doug -- -------------------------------------------------------------- ___ _ Doug Smith \ / ) P.O. Box 1457 ========= Los Gatos, CA 95031-1457 _ / \ / \ _ TEL/FAX: 408-356-4186/358-3799 / /\ \ ] / /\ \ Mobile: 408-858-4528 | q-----() | o | Email: [email protected][2] \ _ / ] \ _ / Web: http://www.dsmith.org[3] -------------------------------------------------------------- --- Links --- 1 http://emcesd.com/tt2010/tt120210.htm 2 mailto:[email protected] 3 http://www.dsmith.org ------------------------------------------------------------------ To unsubscribe from si-list: [email protected] with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: http://www.freelists.org/webpage/si-list For help: [email protected] with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: http://www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu - ---------------------------------------------------------------- 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]> All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. 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]>
