RE: ESD generators max Contact discharge level
Another point is that at lower voltages, the real rise times (the dv/dt) can be quite a bit higher --- especially below about 5kV Mike Hopkins KeyTek -Original Message- From: Cortland Richmond [mailto:72146@compuserve.com] Sent: Wednesday, April 25, 2001 2:33 AM To: jrbar...@lexmark.com; ieee pstc list Subject: Re: ESD generators max Contact discharge level Lower voltages, because of less corona, tend to have more energy, sooner, relative to the total. You might pass a 15 kV air discharge test -- but fail, lower. We ALWAYS want margin, and others ALWAYS want none. My experience in a previous area of the industry is, this lasts until a rash of field failures costs someone a lot of money. The nature of the contact discharge test is such that the charge is not even applied to the electrode until it's in position, and then, humidity is not a factor. However, in a dryer atmosphere, you might experience more FIELD failures, since people using the equipment will be charging up to higher voltages. You have a good point, though; for the reason you mention, there is a limit on humidity for doing ESD testing, which I believe is 70 percent -- my references are at the office and I'm at home. Cortland --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall," --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall,"
Re: ESD generators max Contact discharge level
Lower voltages, because of less corona, tend to have more energy, sooner, relative to the total. You might pass a 15 kV air discharge test -- but fail, lower. We ALWAYS want margin, and others ALWAYS want none. My experience in a previous area of the industry is, this lasts until a rash of field failures costs someone a lot of money. The nature of the contact discharge test is such that the charge is not even applied to the electrode until it's in position, and then, humidity is not a factor. However, in a dryer atmosphere, you might experience more FIELD failures, since people using the equipment will be charging up to higher voltages. You have a good point, though; for the reason you mention, there is a limit on humidity for doing ESD testing, which I believe is 70 percent -- my references are at the office and I'm at home. Cortland --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall,"
RE: ESD generators max Contact discharge level
Ed, the main difference has to do with the tip. An air discharge tip is rounded, not sharp. While a contact tip is sharp. Each one will allow a spark to jump the gap to the DUT, but in different ways. > Michael Sundstrom > Product Test Technician EMC > Nokia Mobile Phones, Dallas PCC > > * Email michael.sundst...@nokia.com > % Desk (972) 374-1462 > *Mobile (817) 917-5021 > * Fax (972) 374-0901 amateur call: KB5UKT --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall,"
Re: ESD generators max Contact discharge level
Glyn, I just ran across this paper, which discusses in greater detail how lower ESD voltages can sometimes create greater upset of electronic equipment than high ESD voltages: [496a] Fujiwara, Osamu, "An Analytical Approach to Model Indirect Effect Caused by Electrostatic Discharge," IEICE Transactions on Communications, vol. E-79B no. 4, pp. 483-489, Apr. 4, 1996. (download from http://search.ieice.or.jp/1996/pdf/e79-b_4_483.pdf) John Barnes Advisory Engineer Lexmark International -- Forwarded by John Barnes/Lex/Lexmark on 04/24/2001 11:26 AM --- John Barnes 04/23/2001 10:56 AM To: "Glyn Garside(TUV)" cc: Subject: Re: ESD generators max Contact discharge level (Document link: JRBARNES Mail) Glyn, I have submitted a 21-page article on "Designing Electronic Equipment for ESD Immunity" to Printed Circuit Design magazine. In my literature search, I read over 70 books and nearly 1300 articles/papers/standards/application notes on Electrostatic Discharge (ESD) and related subjects over the last five months According to various authors, air-discharge voltages in the range of 4-6kV are the most likely to upset electronic equipment. At higher voltages you start getting corona from the person/air-discharge tip, which: 1. Slows down or eliminates the initial spike of the ESD zap, which 2. Slows down the risetime of the ESD zap from 0.5-1ns to some 5-10ns, which 3. Narrows the frequency range of the ESD zap from some 1-500MHz down to 1-60MHz or so, which 4. Makes slots and other imperfections in shields look much smaller with respect to the wavelengths of the ESD zap's magnetic and electric fields, greatly reducing leakage through the shields, AND Making unterminated wires, loops, and patches look much smaller than the wavelengths of the fields, greatly reducing coupling into victim circuits: * A monopole (a wire sticking up from a groundplane) is a very efficient antenna when its length is about n * lambda / 4, with n odd. * A dipole is a very efficient antenna when its length is about n * lambda / 2, with n odd. * A loop is a very efficient antenna when its length is about n * lambda, with n odd. There are a bunch of other effects, including resonances in shielded enclosures, resonances with parasitic capacitance/inductance, dI/dt, etc. But in general the wider frequency range of low-voltage ESD has a much higher chance of "getting" us than the high energy of high-voltage ESD. If we use filters without surge protection on input/output (I/O) lines, the energy that can sneak through is proportional to the square of the ESD voltage. So for direct discharges, high ESD voltages will dump more energy into the circuit than low ESD voltages, and thus increase the chances of damage/upset. Since it only takes one coupling path and one susceptible circuit to clobber a product, in our testing we need to make sure that we haven't left any "windows of opportunity" open for ESD. One author recommends ramping up the voltage for ESD tests in 1kV steps. All the others recommend using 2kV steps unless you have reasons to suspect otherwise (such as a narrow window that showed up in a similar product or earlier tests). Quite a few authors also suggest testing to at least 1-2kV above the specified limit to make sure you have some margin. The draft of EN 61000-4-2 that Doug Smith made available to us suggests using 2kV steps in the absence of other requirements (page 21). To reduce the confounding effect of relative humidity on corona and thus on air discharges, all of the current ESD standards that I've seen basically specify that: 1. "the ESD simulator should approach the EUT as quickly as possible without causing damage to the EUT or simulator" (IEC 61000-4-2 draft page 21). 2. "The simulator ... should be followed through until the electrode touches the surface." (ditto). John Barnes Advisory Engineer Lexmark International [3] Electrostatic Discharge (ESD) Protection Test Handbook, 2nd ed. KeyTek Instruments Corp., Burlington, MA, 1986. [17] Boxleitner, Warren, Electrostatic Discharge and Electronic Equipment-- A Practical Guide for Designing to Prevent ESD Problems. IEEE Press, New York, 1989. [32] Greason, William D., Electrostatic Damage in Electronics: Devices and Systems. John Wiley & Sons, New York, 1987. [34] Hartal, Oren, Electromagnetic Compatibility By Design 4th ed. R&B Enterprises, West Conshohocken, PA, 1996. [39] Kimmel, William D, and Gerke, Daryl D., Electromagnetic Compatibility in Medical Equipment. IEEE Press and Interpharm Press, Piscataway, NY, 1995. [41] Kodali,
Re: ESD generators max Contact discharge level
"Glyn Garside(TUV)" on 04/21/2001 12:57:30 AM Please respond to "Glyn Garside(TUV)" To: "Douglas C. Smith" cc: emc-pstc%ieee@interlock.lexmark.com, owner-emc-pstc%ieee@interlock.lexmark.com, Terry Meck (bcc: John Barnes/Lex/Lexmark) Subject: Re: ESD generators max Contact discharge level >>On the other hand very low voltage (and energy) events, such as jingling >>change have very high di/dt because of the tens of ps risetimes that >>occur at low voltage. I think this is why, as I recall, some (maybe all?) IEC standards require you to test not only to the ESD level indicated, but also the lower levels too. For example, if you are required to test at level 4, you are also required test at levels 3, 2 and 1. This is counter-intuitive -- "Surely the highest voltage is the worst case?" -- but apparently grounded in good physics, which Doug explains better than I would. PS: As to testing at higher levels than typical IEC values, I have read that the human body can, rarely, gain a charge of up to about 30kV(??), in conditions of low RH. Others may have better insight into this. Also, some manufacturers may want to build some "margin" into their test results: if five samples pass at 8kV, how sure can you be that the next 995 production units would also pass? PPS: I have a question of my own, drifting off topic slightly: if the relative humidity was fairly high when you passed the ESD test, and you retest (esp. air discharge?, or indirect discharge?) some months later when humidity is lower, could the same EUT now fail? (I think the answer is, yes?) Best Regards, Glyn Glyn R. Garside (mailto:ggars...@us.tuv.com) Senior Engineer, Industrial Machinery Division TUV Rheinland of North America, Inc. (Chicago Office) 1945 Techny Rd, Unit 4, NORTHBROOK, IL 60062-5357, USA http://www.us.tuv.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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall,"
RE: ESD generators max Contact discharge level
My apologies to the group. I see what Ed is driving at. I should have specified "Direct Air Discharge" as opposed to just "Air Discharge". I assumed that everyone would assume the "Direct" part. It would have saved Ed, and possibly others, some confusion. IEC 1000-4-2 takes great pains to describe at least four different types of discharges, it takes the full definition in order to tell one from the other. > -Original Message- > From: Price, Ed [SMTP:ed.pr...@cubic.com] > Sent: Tuesday, April 24, 2001 10:04 AM > To: 'Gary McInturff'; 'Chris Maxwell'; 'EMC-PSTC Internet Forum' > Subject: RE: ESD generators max Contact discharge level > > Chris: > > Sorry, my ignorance is showing! I was assuming that an "air discharge" was > just that; i.e., a test electrode to test electrode discharge in air some > specific distance from the EUT. From your elaboration, I now see that > "contact discharge" is a deliberate conductive connection before > application > of the discharge. And an "air discharge" is actually a "touching" > discharge > to some surface, like paint or the non-conductive membrane over a keypad, > which may then penetrate the dielectric and discharge onto the conductive > paths below. > > Gary; don't forget that many industrial processes create ESD events, from > chip handlers to conveyor belts to fuel transferring. > > Regards, > > Ed > > Ed Price > ed.pr...@cubic.com > Electromagnetic Compatibility Lab > Cubic Defense Systems > San Diego, CA USA > 858-505-2780 (Voice) > 858-505-1583 (Fax) > Military & Avionics EMC Services Is Our Specialty > Shake-Bake-Shock - Metrology - Reliability Analysis > > > > >-Original Message- > >From: Gary McInturff [mailto:gary.mcintu...@worldwidepackets.com] > >Sent: Monday, April 23, 2001 3:39 PM > >To: 'Chris Maxwell'; 'EMC-PSTC Internet Forum' > >Subject: RE: ESD generators max Contact discharge level > > > > > > > >Hi Chris, > > I agree with your whole heartedly. If it weren't for > >people there > >wouldn't be an ESD problem. We are wither walking around > >charging others > >stuff like furniture or worse yet we charge ourselves and the go around > >touching stuff. For the most part I know of nobody that is > >able to hold a > >charge until they contact a surface and then dump it to ground > >at will. Even > >though somewhat less repeatable I think the test should > >attempt to model the > >discharge mode - Through air as people approach the equipment. > > I also have a hunch, and I have no data nor have I studied real > >hard, but I believe that if the guns are designed be more and > >more alike, a > >great deal of the variability goes out of the test. The test > >operator comes > >next, but they can be trained for reasonable repeatability when the are > >taught some of the issues. > > Even some of that gets leveled out if the test is run > >carefully and > >uses multiple test levels, say every 2k or even at 1K increments. > > Gary > > > >-Original Message- > >From: Chris Maxwell [mailto:chris.maxw...@gnnettest.com] > >Sent: Monday, April 23, 2001 11:36 AM > >To: 'EMC-PSTC Internet Forum' > >Subject: FW: ESD generators max Contact discharge level > > > > > > > >> Hi Ed, > >> > >> I fully agree that membrane keypads are one of the most common places > >> where a finger could discharge to the instrument. > >> > >> However, I disagree that contact discharge is the > >appropriate test method > >> for these surfaces. Current state of the art in test instruments and > >> methods dictates air discharge testing of such surfaces. Just for > >> clarity's sake, when I say air discharge testing, I mean > >approaching the > >> device under test with a blunt, charged ESD gun tip. If the > >device under > >> test has a weak insulator, an air discharge will occur. > >> > >> The IEC standards use contact discharge testing as the > >"preferred" method > >> because it is more repeatable than air discharge testing. The IEC > >> standards recognize air discharge testing on surfaces that > >won't allow a > >> contact discharge. > >> > >> I could write a book explaining why air discharge testing is > >the closest > >> simulation to real life (unless you're in a
RE: ESD generators max Contact discharge level
Chris: Sorry, my ignorance is showing! I was assuming that an "air discharge" was just that; i.e., a test electrode to test electrode discharge in air some specific distance from the EUT. From your elaboration, I now see that "contact discharge" is a deliberate conductive connection before application of the discharge. And an "air discharge" is actually a "touching" discharge to some surface, like paint or the non-conductive membrane over a keypad, which may then penetrate the dielectric and discharge onto the conductive paths below. Gary; don't forget that many industrial processes create ESD events, from chip handlers to conveyor belts to fuel transferring. Regards, Ed Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis >-Original Message- >From: Gary McInturff [mailto:gary.mcintu...@worldwidepackets.com] >Sent: Monday, April 23, 2001 3:39 PM >To: 'Chris Maxwell'; 'EMC-PSTC Internet Forum' >Subject: RE: ESD generators max Contact discharge level > > > >Hi Chris, > I agree with your whole heartedly. If it weren't for >people there >wouldn't be an ESD problem. We are wither walking around >charging others >stuff like furniture or worse yet we charge ourselves and the go around >touching stuff. For the most part I know of nobody that is >able to hold a >charge until they contact a surface and then dump it to ground >at will. Even >though somewhat less repeatable I think the test should >attempt to model the >discharge mode - Through air as people approach the equipment. > I also have a hunch, and I have no data nor have I studied real >hard, but I believe that if the guns are designed be more and >more alike, a >great deal of the variability goes out of the test. The test >operator comes >next, but they can be trained for reasonable repeatability when the are >taught some of the issues. > Even some of that gets leveled out if the test is run >carefully and >uses multiple test levels, say every 2k or even at 1K increments. > Gary > >-Original Message- >From: Chris Maxwell [mailto:chris.maxw...@gnnettest.com] >Sent: Monday, April 23, 2001 11:36 AM >To: 'EMC-PSTC Internet Forum' >Subject: FW: ESD generators max Contact discharge level > > > >> Hi Ed, >> >> I fully agree that membrane keypads are one of the most common places >> where a finger could discharge to the instrument. >> >> However, I disagree that contact discharge is the >appropriate test method >> for these surfaces. Current state of the art in test instruments and >> methods dictates air discharge testing of such surfaces. Just for >> clarity's sake, when I say air discharge testing, I mean >approaching the >> device under test with a blunt, charged ESD gun tip. If the >device under >> test has a weak insulator, an air discharge will occur. >> >> The IEC standards use contact discharge testing as the >"preferred" method >> because it is more repeatable than air discharge testing. The IEC >> standards recognize air discharge testing on surfaces that >won't allow a >> contact discharge. >> >> I could write a book explaining why air discharge testing is >the closest >> simulation to real life (unless you're in a vacuum) and >another book about >> why contact discharge is used as a repeatable model for air >discharges >> but I'll spare everyone the details. I could explain more >fully if anyone >> is interested. >> >> The manual for my ESD gun (Keytek MiniZap, which is a >compliance grade >> instrument) recommends against contact discharges to >insulated surfaces as >> it has the potential to damage the high voltage relay in the >product. I >> can't speak for other guns. >> . >> For insulated membrane switches, the IEC standards and the >equipment that >> I have dictates that I use air discharge testing. >> >> Until a better test method comes along, I stand by my >original answer to >> Dan's question. >> >> Best regards, >> >> Chris >> >> P.S. Being forever curious, If anyone knows of an ESD >simulator or test >> method that does perform contact discharges to insulated >surfaces, I'd >> love to hear about it. I'm sure that it would be of >interest to the group >> as well. >> >> &g
RE: ESD generators max Contact discharge level
Hi Chris, I agree with your whole heartedly. If it weren't for people there wouldn't be an ESD problem. We are wither walking around charging others stuff like furniture or worse yet we charge ourselves and the go around touching stuff. For the most part I know of nobody that is able to hold a charge until they contact a surface and then dump it to ground at will. Even though somewhat less repeatable I think the test should attempt to model the discharge mode - Through air as people approach the equipment. I also have a hunch, and I have no data nor have I studied real hard, but I believe that if the guns are designed be more and more alike, a great deal of the variability goes out of the test. The test operator comes next, but they can be trained for reasonable repeatability when the are taught some of the issues. Even some of that gets leveled out if the test is run carefully and uses multiple test levels, say every 2k or even at 1K increments. Gary -Original Message- From: Chris Maxwell [mailto:chris.maxw...@gnnettest.com] Sent: Monday, April 23, 2001 11:36 AM To: 'EMC-PSTC Internet Forum' Subject: FW: ESD generators max Contact discharge level > Hi Ed, > > I fully agree that membrane keypads are one of the most common places > where a finger could discharge to the instrument. > > However, I disagree that contact discharge is the appropriate test method > for these surfaces. Current state of the art in test instruments and > methods dictates air discharge testing of such surfaces. Just for > clarity's sake, when I say air discharge testing, I mean approaching the > device under test with a blunt, charged ESD gun tip. If the device under > test has a weak insulator, an air discharge will occur. > > The IEC standards use contact discharge testing as the "preferred" method > because it is more repeatable than air discharge testing. The IEC > standards recognize air discharge testing on surfaces that won't allow a > contact discharge. > > I could write a book explaining why air discharge testing is the closest > simulation to real life (unless you're in a vacuum) and another book about > why contact discharge is used as a repeatable model for air discharges > but I'll spare everyone the details. I could explain more fully if anyone > is interested. > > The manual for my ESD gun (Keytek MiniZap, which is a compliance grade > instrument) recommends against contact discharges to insulated surfaces as > it has the potential to damage the high voltage relay in the product. I > can't speak for other guns. > . > For insulated membrane switches, the IEC standards and the equipment that > I have dictates that I use air discharge testing. > > Until a better test method comes along, I stand by my original answer to > Dan's question. > > Best regards, > > Chris > > P.S. Being forever curious, If anyone knows of an ESD simulator or test > method that does perform contact discharges to insulated surfaces, I'd > love to hear about it. I'm sure that it would be of interest to the group > as well. > > > Ed's email attached * > > > Chris: > > I don't understand why a membrane switchpad would not be tested for > contact > discharge. It think that this is the absolutely most likely place where a > finger, attached to a charged human body, might be applied to the EUT. It > seems to me that you would want to be testing the dielectric strength of > the > insulation over the keypad conductive traces. > > The issue of whether a triggering of the testing gun, without a completed > discharge current, would damage the gun, isn't relevant to the need for > the > test. Dumping 15 or 20 kV to a probe tip, while not exactly trivial, still > shouldn't be critically sensitive to load conditions. > > Regards, > > Ed > > --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall," --- 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
RE: ESD generators max Contact discharge level
Ed, Desirability may be a moot point. Whether you want to test the membrane keypad as a contact discharge or not the test equipment may not let you. The Haefly-Trench ESD gun (PESD 1600?) for one checks continuity through the tip before it enables a contact discharge. If you pull the trigger and there is no continuity it displays a message to that effect and waits to be reset (trigger release). To the second point I agree with Chris that contact discharge is only valid for conductive surfaces. The standard prefers contact discharge WHERE APPLICABLE (emphasis mine) because it is a more repeatable test. It doesn't have the variables of approach speed and such that air discharge does. It does need a conductive surface to be valid. Your example of the membrane being a must test point due to real world considerations is well taken; but the real world event it sees is an air discharge (which is not a defining criteria, the defining criteria is if you have a conductive surface do a contact discharge, even if the real world threat is an air discharge) and do to its physical characteristics (non-conductive) it is tested with an air discharge. This is based on definitions and test procedures for IEC 1000-4-2 and EN 61000-4-2. there may be different requirements in other ESD test standards. There is at least one commercially available ESD gun that will only allow you test in the manner I describe. Paul McCoy -Original Message- From: Price, Ed [mailto:ed.pr...@cubic.com] Sent: Monday, April 23, 2001 9:47 AM To: emc-p...@ieee.org Subject: RE: ESD generators max Contact discharge level >-Original Message- >From: Chris Maxwell [mailto:chris.maxw...@gnnettest.com] >Sent: Monday, April 23, 2001 4:45 AM >To: 'Dan Kinney (A)'; Douglas C. Smith; Terry Meck >Cc: emc-p...@ieee.org >Subject: RE: ESD generators max Contact discharge level > > > >Hi Dan, > >Air discharges are made anywhere on the product where an >insulator covers >possibly sensitive features. > >Membrane keypads are a great example. The keypads contain traces and >circuitry that may be sensitive to ESD. However, since the >outermost layer >is an insulator, making a contact discharge would not be a >real world test. >I believe that it may also damage the contact discharge relay >in certain ESD >generators. I can explain that in more detail if you would >like. In my >experience, membrane keypads are always tested with air discharge. > SNIP > >Chris Maxwell >Design Engineer >NetTest >6 Rhoads Drive, Building 4 >Utica,NY 13502 >email: chris.maxw...@gnnettest.com >phone: 315-266-5128 >fax: 315-797-8024 > Chris: I don't understand why a membrane switchpad would not be tested for contact discharge. It think that this is the absolutely most likely place where a finger, attached to a charged human body, might be applied to the EUT. It seems to me that you would want to be testing the dielectric strength of the insulation over the keypad conductive traces. The issue of whether a triggering of the testing gun, without a completed discharge current, would damage the gun, isn't relevant to the need for the test. Dumping 15 or 20 kV to a probe tip, while not exactly trivial, still shouldn't be critically sensitive to load conditions. Regards, Ed Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall," --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net For policy questions, send mail to: Richard
RE: ESD generators max Contact discharge level
>-Original Message- >From: Chris Maxwell [mailto:chris.maxw...@gnnettest.com] >Sent: Monday, April 23, 2001 4:45 AM >To: 'Dan Kinney (A)'; Douglas C. Smith; Terry Meck >Cc: emc-p...@ieee.org >Subject: RE: ESD generators max Contact discharge level > > > >Hi Dan, > >Air discharges are made anywhere on the product where an >insulator covers >possibly sensitive features. > >Membrane keypads are a great example. The keypads contain traces and >circuitry that may be sensitive to ESD. However, since the >outermost layer >is an insulator, making a contact discharge would not be a >real world test. >I believe that it may also damage the contact discharge relay >in certain ESD >generators. I can explain that in more detail if you would >like. In my >experience, membrane keypads are always tested with air discharge. > SNIP > >Chris Maxwell >Design Engineer >NetTest >6 Rhoads Drive, Building 4 >Utica,NY 13502 >email: chris.maxw...@gnnettest.com >phone: 315-266-5128 >fax: 315-797-8024 > Chris: I don't understand why a membrane switchpad would not be tested for contact discharge. It think that this is the absolutely most likely place where a finger, attached to a charged human body, might be applied to the EUT. It seems to me that you would want to be testing the dielectric strength of the insulation over the keypad conductive traces. The issue of whether a triggering of the testing gun, without a completed discharge current, would damage the gun, isn't relevant to the need for the test. Dumping 15 or 20 kV to a probe tip, while not exactly trivial, still shouldn't be critically sensitive to load conditions. Regards, Ed Ed Price ed.pr...@cubic.com Electromagnetic Compatibility Lab Cubic Defense Systems San Diego, CA USA 858-505-2780 (Voice) 858-505-1583 (Fax) Military & Avionics EMC Services Is Our Specialty Shake-Bake-Shock - Metrology - Reliability Analysis --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall,"
RE: ESD generators max Contact discharge level
Since the contact method requires penetrating thin, cosmetic coatings, it is a bad idea on membrane keypads; bore that sharp point into the contacts and it's ruined even before you hit the electronics. Not that they'd fare all that well with direct discharge! In any case, there is often some more properly accessible metal nearby. Cortland == Original Message Follows >> Date: 23-Apr-01 04:49:02 MsgID: 1078-34050 ToID: 72146,373 From: Chris Maxwell >INTERNET:chris.maxw...@gnnettest.com Subj: RE: ESD generators max Contact discharge level Chrg: $0.00 Imp: Norm Sens: StdReceipt: NoParts: 1 From: Chris Maxwell Subject: RE: ESD generators max Contact discharge level List-Post: emc-pstc@listserv.ieee.org Date: Mon, 23 Apr 2001 07:44:41 -0400 Reply-To: Chris Maxwell Hi Dan, Air discharges are made anywhere on the product where an insulator covers possibly sensitive features. Membrane keypads are a great example. The keypads contain traces and circuitry that may be sensitive to ESD. However, since the outermost layer is an insulator, making a contact discharge would not be a real world test. I believe that it may also damage the contact discharge relay in certain ESD generators. I can explain that in more detail if you would like. In my experience, membrane keypads are always tested with air discharge. There are other surfaces that offer more chance for interpretation and debate. The main sticking point here is the definition of insulation. Some people try to consider paint on a metal surface as insulation. In this case they will only make air discharges to painted metal surfaces. Others do not consider the paint as an insulator, they will poke the contact discharge tip down through the paint until it gets to bare metal and then make contact discharges. The same question arises with insulating passivation treatments such as black anodize treatment on Aluminum. Each product is different and each coating is different, this is where the compliance engineer has to use some honest judgement. My humble opinion is that I poke the tip through paints and passivation coatings of metals to perform contact discharges. If there is an actual piece of material such as a plastic overlay over the metal; then I use air discharge. I have a non-compliance collegue here that used to work on military projects. He has told me that there is a US military standard that actually classifies different metal treatments such as passivation coatings, paints and baked on enamels as "insulators" or not. However, I have never found this standard. In its absence, I have used the rule of thumb above. Chris Maxwell Design Engineer NetTest 6 Rhoads Drive, Building 4 Utica,NY 13502 email: chris.maxw...@gnnettest.com phone: 315-266-5128 fax: 315-797-8024 > -Original Message- > From: Dan Kinney (A) [SMTP:dan.kin...@heapg.com] > Sent: Friday, April 20, 2001 6:07 PM > To: Douglas C. Smith; Terry Meck > Cc: emc-p...@ieee.org > Subject: RE: ESD generators max Contact discharge level > > > While we're on the topic, I have a question (actually a couple) regarding > air discharge. Since contact discharge is the preferred method, as stated > in an earlier message and in EN61000-4-2, Paragraph 5, why would one > perform > the Air Discharge method? The same paragraph states "Air discharges shall > be used where contact discharge cannot be applied." What conditions would > make it such that contact discharge could not be applied? > > Thanks in advance. > Dan Kinney > Horner APG > > > -Original Message- > > From: Douglas C. Smith [SMTP:d...@emcesd.com] > > Sent: Friday, April 20, 2001 2:54 PM > > To: Terry Meck > > Cc: emc-p...@ieee.org > > Subject:Re: ESD generators max Contact discharge level > > > > > > Hi Terry and the group, > > > > Besides the question of finding a generator that can reach the level you > > mention, I am not aware of any natural ESD event that approaches the > > interference potential of even an 8 kV contact discharge. The problem > > comes in that high voltage air discharges have relatively slow > > risetimes, for 16 kV on the order of tens of ns, whereas contact > > discharges maintain a better than 1 ns risetime at all voltages. This > > makes for a much smaller dt to go along with the greater di to make a > > di/dt that is much higher, more than an order of magnitude, than you > > will see for these voltages in nature. > > > > Maybe if you were making atom bomb trigger mechanisms there would be a > > justification for this kind of testing, but not for real equipment. > > > > On the other hand very low voltage (and energy) events, such as
RE: ESD generators max Contact discharge level
Hi Dan, Air discharges are made anywhere on the product where an insulator covers possibly sensitive features. Membrane keypads are a great example. The keypads contain traces and circuitry that may be sensitive to ESD. However, since the outermost layer is an insulator, making a contact discharge would not be a real world test. I believe that it may also damage the contact discharge relay in certain ESD generators. I can explain that in more detail if you would like. In my experience, membrane keypads are always tested with air discharge. There are other surfaces that offer more chance for interpretation and debate. The main sticking point here is the definition of insulation. Some people try to consider paint on a metal surface as insulation. In this case they will only make air discharges to painted metal surfaces. Others do not consider the paint as an insulator, they will poke the contact discharge tip down through the paint until it gets to bare metal and then make contact discharges. The same question arises with insulating passivation treatments such as black anodize treatment on Aluminum. Each product is different and each coating is different, this is where the compliance engineer has to use some honest judgement. My humble opinion is that I poke the tip through paints and passivation coatings of metals to perform contact discharges. If there is an actual piece of material such as a plastic overlay over the metal; then I use air discharge. I have a non-compliance collegue here that used to work on military projects. He has told me that there is a US military standard that actually classifies different metal treatments such as passivation coatings, paints and baked on enamels as "insulators" or not. However, I have never found this standard. In its absence, I have used the rule of thumb above. Chris Maxwell Design Engineer NetTest 6 Rhoads Drive, Building 4 Utica,NY 13502 email: chris.maxw...@gnnettest.com phone: 315-266-5128 fax: 315-797-8024 > -Original Message- > From: Dan Kinney (A) [SMTP:dan.kin...@heapg.com] > Sent: Friday, April 20, 2001 6:07 PM > To: Douglas C. Smith; Terry Meck > Cc: emc-p...@ieee.org > Subject: RE: ESD generators max Contact discharge level > > > While we're on the topic, I have a question (actually a couple) regarding > air discharge. Since contact discharge is the preferred method, as stated > in an earlier message and in EN61000-4-2, Paragraph 5, why would one > perform > the Air Discharge method? The same paragraph states "Air discharges shall > be used where contact discharge cannot be applied." What conditions would > make it such that contact discharge could not be applied? > > Thanks in advance. > Dan Kinney > Horner APG > > > -Original Message- > > From: Douglas C. Smith [SMTP:d...@emcesd.com] > > Sent: Friday, April 20, 2001 2:54 PM > > To: Terry Meck > > Cc: emc-p...@ieee.org > > Subject:Re: ESD generators max Contact discharge level > > > > > > Hi Terry and the group, > > > > Besides the question of finding a generator that can reach the level you > > mention, I am not aware of any natural ESD event that approaches the > > interference potential of even an 8 kV contact discharge. The problem > > comes in that high voltage air discharges have relatively slow > > risetimes, for 16 kV on the order of tens of ns, whereas contact > > discharges maintain a better than 1 ns risetime at all voltages. This > > makes for a much smaller dt to go along with the greater di to make a > > di/dt that is much higher, more than an order of magnitude, than you > > will see for these voltages in nature. > > > > Maybe if you were making atom bomb trigger mechanisms there would be a > > justification for this kind of testing, but not for real equipment. > > > > On the other hand very low voltage (and energy) events, such as jinjling > > change have very high di/dt because of the tens of ps risetimes that > > occur at low voltage. The combination of high voltage (and energy) with > > fast risetimes is too severe and meeting such a test is a waste of money > > for most equipment. > > > > Doug > > > > Terry Meck wrote: > > > > > > Hello again: > > > > > > Does anyone recall if there were any standard called for or ESD > > generator that simulated as the case may be => +-10 kV CONTACT > discharge. > > > > > > We have a customer that is specifying passing +-16 kV ESD without > > referring to AIR or Contact discharge. I am inclined to ask what they > > have in mind since I have not seen any generators that go that high in > the > > Contact
Re: ESD generators max Contact discharge level
Hi Glyn, Here is one way to approach 30kV. First, slide out of your car seat, the Ford Taurus is great for this effect. This puts a charge on your behind. As you get out of the car (everything is plastic so you remain charged with respect to the car) your voltage rises because Q=CV. Q stays the same (charge on your behind) but since C to the car goes down, voltage goes up. Then you go to close the metal door and a huge spark jumps between your hand and the door. Usually this results in jumping into the air muttering a few four letter words sometimes ending in (I am sure this happens with other cars, I just happen to own Fords, which I like) "F O R D". I wonder why the car companies don't make seat material out of anti-static material BTW, contact discharge has the same risetime at all reasonable voltages, as opposed to air discharges, but still some equipment will fail at a low voltage and pass at high voltages. I can imagine a few ways circuits might do this. The effect is more pronunced with air discharge because of the risetime dependence on voltage (really arc length and whatever effects that, including speed of approach). Doug "Glyn Garside(TUV)" wrote: > > >>On the other hand very low voltage (and energy) events, such as jingling > >>change have very high di/dt because of the tens of ps risetimes that > >>occur at low voltage. > > I think this is why, as I recall, some (maybe all?) IEC standards require > you to test not only to the ESD level indicated, but also the lower levels > too. For example, if you are required to test at level 4, you are also > required test at levels 3, 2 and 1. This is counter-intuitive -- "Surely > the highest voltage is the worst case?" -- but apparently grounded in good > physics, which Doug explains better than I would. > > PS: As to testing at higher levels than typical IEC values, I have read > that the human body can, rarely, gain a charge of up to about 30kV(??), in > conditions of low RH. Others may have better insight into this. Also, some > manufacturers may want to build some "margin" into their test results: if > five samples pass at 8kV, how sure can you be that the next 995 production > units would also pass? > > PPS: I have a question of my own, drifting off topic slightly: if the > relative humidity was fairly high when you passed the ESD test, and you > retest (esp. air discharge?, or indirect discharge?) some months later when > humidity is lower, could the same EUT now fail? (I think the answer is, > yes?) > > Best Regards, Glyn > > Glyn R. Garside (mailto:ggars...@us.tuv.com) > Senior Engineer, Industrial Machinery Division > TUV Rheinland of North America, Inc. (Chicago Office) > 1945 Techny Rd, Unit 4, NORTHBROOK, IL 60062-5357, USA > http://www.us.tuv.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: > Michael Garretson:pstc_ad...@garretson.org > Dave Healddavehe...@mediaone.net > > 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://www.rcic.com/ click on "Virtual Conference Hall," -- --- ___ _ 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: d...@dsmith.org \ _ /]\ _ / Website: http://www.dsmith.org --- --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall,"
Re: ESD generators max Contact discharge level
>>On the other hand very low voltage (and energy) events, such as jingling >>change have very high di/dt because of the tens of ps risetimes that >>occur at low voltage. I think this is why, as I recall, some (maybe all?) IEC standards require you to test not only to the ESD level indicated, but also the lower levels too. For example, if you are required to test at level 4, you are also required test at levels 3, 2 and 1. This is counter-intuitive -- "Surely the highest voltage is the worst case?" -- but apparently grounded in good physics, which Doug explains better than I would. PS: As to testing at higher levels than typical IEC values, I have read that the human body can, rarely, gain a charge of up to about 30kV(??), in conditions of low RH. Others may have better insight into this. Also, some manufacturers may want to build some "margin" into their test results: if five samples pass at 8kV, how sure can you be that the next 995 production units would also pass? PPS: I have a question of my own, drifting off topic slightly: if the relative humidity was fairly high when you passed the ESD test, and you retest (esp. air discharge?, or indirect discharge?) some months later when humidity is lower, could the same EUT now fail? (I think the answer is, yes?) Best Regards, Glyn Glyn R. Garside (mailto:ggars...@us.tuv.com) Senior Engineer, Industrial Machinery Division TUV Rheinland of North America, Inc. (Chicago Office) 1945 Techny Rd, Unit 4, NORTHBROOK, IL 60062-5357, USA http://www.us.tuv.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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall,"
Re: ESD generators max Contact discharge level
Hi Dan, Contact discharge is meant to be applied to conductive surfaces. If a product has a plastic case, breakdown voltage (through seams and holes) is the important parameter. This is best done with air discharge, the object of which is not to have one. Doug "Dan Kinney (A)" wrote: > > While we're on the topic, I have a question (actually a couple) regarding > air discharge. Since contact discharge is the preferred method, as stated > in an earlier message and in EN61000-4-2, Paragraph 5, why would one perform > the Air Discharge method? The same paragraph states "Air discharges shall > be used where contact discharge cannot be applied." What conditions would > make it such that contact discharge could not be applied? > > Thanks in advance. > Dan Kinney > Horner APG > > > -Original Message- > > From: Douglas C. Smith [SMTP:d...@emcesd.com] > > Sent: Friday, April 20, 2001 2:54 PM > > To: Terry Meck > > Cc: emc-p...@ieee.org > > Subject: Re: ESD generators max Contact discharge level > > > > > > Hi Terry and the group, > > > > Besides the question of finding a generator that can reach the level you > > mention, I am not aware of any natural ESD event that approaches the > > interference potential of even an 8 kV contact discharge. The problem > > comes in that high voltage air discharges have relatively slow > > risetimes, for 16 kV on the order of tens of ns, whereas contact > > discharges maintain a better than 1 ns risetime at all voltages. This > > makes for a much smaller dt to go along with the greater di to make a > > di/dt that is much higher, more than an order of magnitude, than you > > will see for these voltages in nature. > > > > Maybe if you were making atom bomb trigger mechanisms there would be a > > justification for this kind of testing, but not for real equipment. > > > > On the other hand very low voltage (and energy) events, such as jinjling > > change have very high di/dt because of the tens of ps risetimes that > > occur at low voltage. The combination of high voltage (and energy) with > > fast risetimes is too severe and meeting such a test is a waste of money > > for most equipment. > > > > Doug > > > > Terry Meck wrote: > > > > > > Hello again: > > > > > > Does anyone recall if there were any standard called for or ESD > > generator that simulated as the case may be => +-10 kV CONTACT discharge. > > > > > > We have a customer that is specifying passing +-16 kV ESD without > > referring to AIR or Contact discharge. I am inclined to ask what they > > have in mind since I have not seen any generators that go that high in the > > Contact mode. > > > I suspect the writer of the SOW knows nothing and the engineering group > > only thinks Air Discharge. > > > > > > What do you all think? > > > > > > Terry J. Meck > > > Accu-Sort Systems Inc. > > > > > > --- > > > 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: > > > Michael Garretson:pstc_ad...@garretson.org > > > Dave Healddavehe...@mediaone.net > > > > > > 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://www.rcic.com/ click on "Virtual Conference Hall," > > > > -- > > --- > > ___ _ 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: d...@dsmith.org > > \ _ /]\ _ / Website: http://www.dsmith.org > > --- > > > > --- > > This message is from the IEEE EMC Society Pr
RE: ESD generators max Contact discharge level
While we're on the topic, I have a question (actually a couple) regarding air discharge. Since contact discharge is the preferred method, as stated in an earlier message and in EN61000-4-2, Paragraph 5, why would one perform the Air Discharge method? The same paragraph states "Air discharges shall be used where contact discharge cannot be applied." What conditions would make it such that contact discharge could not be applied? Thanks in advance. Dan Kinney Horner APG > -Original Message- > From: Douglas C. Smith [SMTP:d...@emcesd.com] > Sent: Friday, April 20, 2001 2:54 PM > To: Terry Meck > Cc: emc-p...@ieee.org > Subject: Re: ESD generators max Contact discharge level > > > Hi Terry and the group, > > Besides the question of finding a generator that can reach the level you > mention, I am not aware of any natural ESD event that approaches the > interference potential of even an 8 kV contact discharge. The problem > comes in that high voltage air discharges have relatively slow > risetimes, for 16 kV on the order of tens of ns, whereas contact > discharges maintain a better than 1 ns risetime at all voltages. This > makes for a much smaller dt to go along with the greater di to make a > di/dt that is much higher, more than an order of magnitude, than you > will see for these voltages in nature. > > Maybe if you were making atom bomb trigger mechanisms there would be a > justification for this kind of testing, but not for real equipment. > > On the other hand very low voltage (and energy) events, such as jinjling > change have very high di/dt because of the tens of ps risetimes that > occur at low voltage. The combination of high voltage (and energy) with > fast risetimes is too severe and meeting such a test is a waste of money > for most equipment. > > Doug > > Terry Meck wrote: > > > > Hello again: > > > > Does anyone recall if there were any standard called for or ESD > generator that simulated as the case may be => +-10 kV CONTACT discharge. > > > > We have a customer that is specifying passing +-16 kV ESD without > referring to AIR or Contact discharge. I am inclined to ask what they > have in mind since I have not seen any generators that go that high in the > Contact mode. > > I suspect the writer of the SOW knows nothing and the engineering group > only thinks Air Discharge. > > > > What do you all think? > > > > Terry J. Meck > > Accu-Sort Systems Inc. > > > > --- > > 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: > > Michael Garretson:pstc_ad...@garretson.org > > Dave Healddavehe...@mediaone.net > > > > 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://www.rcic.com/ click on "Virtual Conference Hall," > > -- > --- > ___ _ 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: d...@dsmith.org > \ _ /]\ _ / Website: http://www.dsmith.org > --- > > --- > 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: > Michael Garretson:pstc_ad...@garretson.org > Dave Healddavehe...@mediaone.net > > 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://www.rcic.com/ click on "Virtual Conference Hall,&qu
Re: ESD generators max Contact discharge level
The only generators that I know of that did contact discharge above 10 KV were the Experimental Physics, later sold by Electro-Metrics. There were 7.5, 15, 25 and 30 kV contact discharge models. But those have not been made in a while and I also doubt that the SOW writer meant contact discharge for those levels. --- Terry Meck wrote: > > Hello again: > > Does anyone recall if there were any standard called for or ESD generator that > simulated as the case may be => +-10 kV CONTACT discharge. > > We have a customer that is specifying passing +-16 kV ESD without referring > to AIR > or Contact discharge. I am inclined to ask what they have in mind since I > have > not seen any generators that go that high in the Contact mode. > I suspect the writer of the SOW knows nothing and the engineering group only > thinks Air Discharge. > > What do you all think? > > Terry J. Meck > Accu-Sort Systems Inc. > > > --- > 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: > Michael Garretson:pstc_ad...@garretson.org > Dave Healddavehe...@mediaone.net > > 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://www.rcic.com/ click on "Virtual Conference Hall," > = Best Regards Hans Mellberg Regulatory Compliance Consultant and Design Services By the Pacific Coast next to Silicon Valley Santa Cruz, CA, USA 408-507-9694 __ Do You Yahoo!? Yahoo! Auctions - buy the things you want at great prices http://auctions.yahoo.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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall,"
Re: ESD generators max Contact discharge level
I understood that only one company world wide had the patent for making the mercury wetted relay used in contact discharge ciruits, ABB if I remember correctly. I alos understood that these arc over at levels above 8 Kv. Is there a higher voltage offering available elsewhere? regards John Cronin >From: "Glyn Garside/TUV" >Reply-To: "Glyn Garside/TUV" >To: "Terry Meck" >CC: emc-p...@ieee.org >Subject: Re: ESD generators max Contact discharge level >Date: Fri, 20 Apr 2001 14:11:43 -0500 > > > > >>Does anyone recall [...] ESD generator that simulated [...] => +-10 kV >CONTACT discharge. > >I agree, your client _probably_ meant air, but better to ask. > >Nevertheless, as I recall, NoiseKen makes an ESD tester that does 16kV >contact / 30kV air. >http://www.noiseken.com/english/equip/equip.htm > > >Also, there seems to be a Haefely model -- PESD 3000 -- that offers 25kV >contact / 30kV air(?): >http://www.compliancesys.com/transientsystems.htm >There are probably other products, and most certainly other >vendors/distributors. (This was the first one my web search engine came up >with.) > >Online lists of vendors include: http://rbitem.com/products/default.asp > >USUAL DISCLAIMERS APPLY! >For information only. This is not intended to be an endorsement of any >product, vendor or website. > >Best Regards, Glyn > > >Glyn R. Garside (mailto:ggars...@us.tuv.com) >Senior Engineer, Industrial Machinery Division >TUV Rheinland of North America, Inc. (Chicago Office) >1945 Techny Rd, Unit 4, NORTHBROOK, IL 60062-5357, USA >http://www.us.tuv.com TEL 847-562-9888 ext 25 > > >--- >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: > Michael Garretson: pstc_ad...@garretson.org > Dave Heald davehe...@mediaone.net > >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://www.rcic.com/ click on "Virtual Conference Hall," > Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall,"
Re: ESD generators max Contact discharge level
Hi Terry and the group, Besides the question of finding a generator that can reach the level you mention, I am not aware of any natural ESD event that approaches the interference potential of even an 8 kV contact discharge. The problem comes in that high voltage air discharges have relatively slow risetimes, for 16 kV on the order of tens of ns, whereas contact discharges maintain a better than 1 ns risetime at all voltages. This makes for a much smaller dt to go along with the greater di to make a di/dt that is much higher, more than an order of magnitude, than you will see for these voltages in nature. Maybe if you were making atom bomb trigger mechanisms there would be a justification for this kind of testing, but not for real equipment. On the other hand very low voltage (and energy) events, such as jinjling change have very high di/dt because of the tens of ps risetimes that occur at low voltage. The combination of high voltage (and energy) with fast risetimes is too severe and meeting such a test is a waste of money for most equipment. Doug Terry Meck wrote: > > Hello again: > > Does anyone recall if there were any standard called for or ESD generator > that simulated as the case may be => +-10 kV CONTACT discharge. > > We have a customer that is specifying passing +-16 kV ESD without referring > to AIR or Contact discharge. I am inclined to ask what they have in mind > since I have not seen any generators that go that high in the Contact mode. > I suspect the writer of the SOW knows nothing and the engineering group only > thinks Air Discharge. > > What do you all think? > > Terry J. Meck > Accu-Sort Systems Inc. > > --- > 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: > Michael Garretson:pstc_ad...@garretson.org > Dave Healddavehe...@mediaone.net > > 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://www.rcic.com/ click on "Virtual Conference Hall," -- --- ___ _ 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: d...@dsmith.org \ _ /]\ _ / Website: http://www.dsmith.org --- --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall,"
Re: ESD generators max Contact discharge level
>>Does anyone recall [...] ESD generator that simulated [...] => +-10 kV CONTACT discharge. I agree, your client _probably_ meant air, but better to ask. Nevertheless, as I recall, NoiseKen makes an ESD tester that does 16kV contact / 30kV air. http://www.noiseken.com/english/equip/equip.htm Also, there seems to be a Haefely model -- PESD 3000 -- that offers 25kV contact / 30kV air(?): http://www.compliancesys.com/transientsystems.htm There are probably other products, and most certainly other vendors/distributors. (This was the first one my web search engine came up with.) Online lists of vendors include: http://rbitem.com/products/default.asp USUAL DISCLAIMERS APPLY! For information only. This is not intended to be an endorsement of any product, vendor or website. Best Regards, Glyn Glyn R. Garside (mailto:ggars...@us.tuv.com) Senior Engineer, Industrial Machinery Division TUV Rheinland of North America, Inc. (Chicago Office) 1945 Techny Rd, Unit 4, NORTHBROOK, IL 60062-5357, USA http://www.us.tuv.com TEL 847-562-9888 ext 25 --- 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: Michael Garretson:pstc_ad...@garretson.org Dave Healddavehe...@mediaone.net 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://www.rcic.com/ click on "Virtual Conference Hall,"
