As has been pointed out by Mr. Woods, humidity is only one of many parameters involved with ESD. And simulating a dry environment in a chamber that's completely lined with metal surfaces might not be sufficient for simulating a dry customer environment.
ESD failures at differing levels of voltage is an interesting problem since I've had at least two different types of failures each with entirely different casues. 1. A unacceptable hard ESD failure at a level of say 'x KV' and any level higher is most likely a grounding problem. To lower level 'x KV', look at the grounding setup. 2. A unacceptable hard ESD failure at a level of say 'x KV' but possibly no failure above this until a higher level is reached is more a decoupling problem in combination with a grounding problem. For instance, by a "grounding problem" I mean ground wire too short, improperly placed, ground wire too small, maybe braid should be used, maybe a strip of copper should be used, and if a braid or strip of copper are being used then maybe they're not wide enough, etc etc ... By a "decoupling problem" in combination with a grounding problem, I mean the ground problem described above in concert with incorrectly sized decoupling caps, the decoupling caps are improperly placed, leads too long on the caps, wrong sized ferrites if used, improperly placed ferrites, etc etc etc ... Regards, Doug McKean ------------------------------------------- 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: [email protected] Dave Heald: [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] 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"
