Something's bothering me about this discussion. It's not what people have said that I disagree. Maybe it's to be put in the FWIW department,
1MV breaks down 1 meter of air @ STP. It then follows that 1KV breaks down 1 mm of air. So, that's 1mm AIR/1KV. FR4 has a dielectric factor of about 4.7. That simply means it's 4.7 times stronger than air. Therefore, *in theory* 1KV should in theory break down (1/4.7) mm of FR4, or 0.21 mm of FR4. So, that's 0.21mm FR4/1KV. Now the circuit you're working with, primary or TNV, ... will decide the highest amount of stress during test. If it's going to be 2KVDC, then it's 0.4 mm. If it's going to be 3KVDC, 0.6mm. If it's going to be 8KV with some ESD test, then it's 1.6mm. That's between layers. Wanna put a safety factor of x2 in? The 2KV changes to 0.8mm. The 3KV changes to 1.2mm. Etc ... Something to consider. That's strictly between layers. I'd personally use the air breakdown rule of 1mm/1KV for planes in proximity to vias. And I would always work this out by myself before looking up the standard. And *ALWAYS*, check the standard. 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: 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"
