ESD Testing Method
The comments reminded me of a story I heard about some years ago. A pcb design included a metal canned crystal oscillator, the unit being mounted in a metal enclosure. During ESD testing, the system functioned correctly until before the end of the requisite zaps, the oscillator failed. After this had happened to several units, investigation showed that the oscillator's metal can was floating. The can to enclosure capacitance was such that after a few zaps sufficient charge was transferred to the can to cause an internal discharge, thereby destroying the oscillator. Regards, Neil Helsby ** This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This footnote also confirms that this email message has been swept by MIMEsweeper for the presence of computer viruses. www.mimesweeper.com ** --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: ESD Testing Method
Alex, Amendment 2:2001 to EN 61000-4-2:1995 (same as Amendment A2:2000 to IEC 61000-4-2:1995) calls for discharging ungrounded equipment, or ungrounded part(s) of equipment between ESD zaps. You use a bleeder cable with 470k resistors at both ends, connected to the horizontal coupling plane for tabletop equipment. You may leave the bleeder cable attached if it doesn't bother the equipment under test (EUT). But the definitive method is to briefly touch the bleeder cable to the EUT, zap the EUT, briefly touch the bleeder cable to the EUT, etc. This amendment also permits: * Long delays between ESD zaps. * Using a carbon-fiber brush with bleeder resistors. * Using an air ionizer (must be turned off for the air-discharge zaps). John Barnes KS4GL, SM IEEE dBi Corporation http://www.dbicorporation.com/ --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
Re: ESD Testing Method
Amendment 2 to IEC 61000-4-2:1995 specifically addresses the test method for ungrounded equipment. Refer to section 7.1.3 of that standard. To answer your first question, yes the charge applied to the product should be discharged before applying the next discharge. Regarding your follow up question, if you apply +8kV discharge followed by -8kV discharge, without removing the charge from the EUT between the discharges, then the actual potential voltage is 16kV which could very well overstress the product. Jim Hulbert Pitney Bowes Alex McNeil alex.mcneil@ingenicoforTo: 'emc-p...@majordomo.ieee.org' emc-p...@majordomo.ieee.org tronic.com cc: Sent by:Subject: ESD Testing Method owner-emc-pstc@majordomo .ieee.org 12/03/2002 11:15 AM Please respond to Alex McNeil Hi Guys, 1. For double insulated products (non-earthed) is it correct to state that the ESD test point, for Contact Discharge (CD) tests, should be discharged prior to applying the next discharge (I am sure I read this somewhere, but)? 2. As a follow on from the first question, I have a product that will pass +8KV Contact Discharge (CD) in +2KV steps. It will also pass -8KV CD in -2KV steps. However, if I test +XKV (50 zaps) followed by -XKV (1 zap) it will fail. What is the correct procedure as the standard does not say if +CD should follow -CD or vice versa or step up with the same polarity? In my opinion it would be unlikely in a particular customer environment that the +XKV would be quickly followed by a -XKV (or vice versa). I look forward, as per usual, to your kind and expert responses. Kind Regards Alex McNeil Principal Engineer Tel: +44 (0)131 479 8375 Fax:+44 (0)131 479 8321 email: alex.mcn...@ingenicofortronic.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click
RE: ESD Testing Method
Dear Alex McNeil, The intend of the standard is that each discharge is an individual event. This means: Electromagnetic consequence === All charges need to be drained before the next discharge is applied. You may use an Ionizer, a conductive brush, a ground wire etc. to remove the charge from the EUT. Be aware: An Ionizer may change the test results for air discharges a lot. Software consequence It is not the aim to apply an discharge while the EUT is still in some error correcting algorithm. So one can apply discharges at a fast rate, e.g., 20 pulses a sec to up the number of discharges (with 10 discharges the ESD test result uncertainty may be dominated by the time dependence of the susceptability function). Still, one needs to make sure that the EUT is back to its original software status before the next ESD is applied. David Pommerenke -Original Message- From: Alex McNeil [mailto:alex.mcn...@ingenicofortronic.com] Sent: Tuesday, December 03, 2002 10:16 AM To: 'emc-p...@majordomo.ieee.org' Subject: ESD Testing Method Hi Guys, 1. For double insulated products (non-earthed) is it correct to state that the ESD test point, for Contact Discharge (CD) tests, should be discharged prior to applying the next discharge (I am sure I read this somewhere, but)? 2. As a follow on from the first question, I have a product that will pass +8KV Contact Discharge (CD) in +2KV steps. It will also pass -8KV CD in -2KV steps. However, if I test +XKV (50 zaps) followed by -XKV (1 zap) it will fail. What is the correct procedure as the standard does not say if +CD should follow -CD or vice versa or step up with the same polarity? In my opinion it would be unlikely in a particular customer environment that the +XKV would be quickly followed by a -XKV (or vice versa). I look forward, as per usual, to your kind and expert responses. Kind Regards Alex McNeil Principal Engineer Tel: +44 (0)131 479 8375 Fax:+44 (0)131 479 8321 email: alex.mcn...@ingenicofortronic.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: ESD Testing Method
Alex, The new A2 (Feb 2001) of EN61000-4-2:1995 is very clear on this point. Paragraph 7.1.3 states the charge on the EUT shall be removed prior to each applied ESD pulse. I think this would take care of the problem you are seeing with the charge reversal that you talk about in question 2. Dan Kinney Horner APG --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
RE: ESD Testing Method
Most labs I have ever worked with return the EUT to a neutral level prior to applying opposite polarity discharges, which means use a wire attached to reference ground to short out any accumulated charge. However this has usually been with air discharge to non-conductive surfaces such as an overlay. The reasoning is that an opposite polarity discharge is twice the required level and does not relate to a real world event. Darrell Locke Advanced Input Devices -Original Message- From: Alex McNeil [mailto:alex.mcn...@ingenicofortronic.com] Sent: Tuesday, December 03, 2002 8:16 AM To: 'emc-p...@majordomo.ieee.org' Subject: ESD Testing Method Hi Guys, 1. For double insulated products (non-earthed) is it correct to state that the ESD test point, for Contact Discharge (CD) tests, should be discharged prior to applying the next discharge (I am sure I read this somewhere, but)? 2. As a follow on from the first question, I have a product that will pass +8KV Contact Discharge (CD) in +2KV steps. It will also pass -8KV CD in -2KV steps. However, if I test +XKV (50 zaps) followed by -XKV (1 zap) it will fail. What is the correct procedure as the standard does not say if +CD should follow -CD or vice versa or step up with the same polarity? In my opinion it would be unlikely in a particular customer environment that the +XKV would be quickly followed by a -XKV (or vice versa). I look forward, as per usual, to your kind and expert responses. Kind Regards Alex McNeil Principal Engineer Tel: +44 (0)131 479 8375 Fax:+44 (0)131 479 8321 email: alex.mcn...@ingenicofortronic.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
ESD Testing Method
Hi Guys, 1. For double insulated products (non-earthed) is it correct to state that the ESD test point, for Contact Discharge (CD) tests, should be discharged prior to applying the next discharge (I am sure I read this somewhere, but)? 2. As a follow on from the first question, I have a product that will pass +8KV Contact Discharge (CD) in +2KV steps. It will also pass -8KV CD in -2KV steps. However, if I test +XKV (50 zaps) followed by -XKV (1 zap) it will fail. What is the correct procedure as the standard does not say if +CD should follow -CD or vice versa or step up with the same polarity? In my opinion it would be unlikely in a particular customer environment that the +XKV would be quickly followed by a -XKV (or vice versa). I look forward, as per usual, to your kind and expert responses. Kind Regards Alex McNeil Principal Engineer Tel: +44 (0)131 479 8375 Fax:+44 (0)131 479 8321 email: alex.mcn...@ingenicofortronic.com --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on browse and then emc-pstc mailing list
