Okay, now don't everyone write to my layout guys, but I never bothered to tell them they could change the constraint files for closer routing on inner layers, so they do apply the spacings. I have try to keep an eye for it causing us extra layers or any real grief and it hasn't. Gary
-----Original Message----- From: T.Sato [mailto:vef00...@nifty.ne.jp] Sent: Wednesday, August 14, 2002 6:41 PM To: emc-p...@majordomo.ieee.org Subject: RE: Creepage on PCB Internal Layers On Wed, 14 Aug 2002 15:22:21 -0400, John Juhasz <john.juh...@ge-interlogix.com> wrote: > While a different standard was originally referenced in this thread, > I'd like to consider for a moment Chris Maxwell's question > "...there should be some minimum distance... on an inner layer of the > board"L > The 950-based standards have guidelines in this regard. > > In section 2.9.6 'Enclosed or Sealed Parts' > "For components or sub-assemblies which are enclosed or hermetically > sealed against ingress of dirt or moisture, and which satisfy the following > compliance requirements, the minimum internal CREEPAGE DISTANCES and > CLEARANCES can be the values for Pollution Degree 1." I think the clause wouldn't be applied in this situation. In 60950, applicable clauses are 2.10.5.3 and 2.10.5.1 (I'm not reading genuine IEC/EN 60950, and I'm sorry if I'm wrong) - the former states that distance through insulation would be applied in such situation, and the latter set minimum thickness of 0.4mm for supplementary and reinforced insulation for peak working voltage greater than 71V. However, I think applying minimum distance for pollution degree 1 or that for coated PCBs (clause 2.10.6) for inner layers when designing PCBs are not bad idea, although both of them wouldn't be applied here. The latter set, for example, minimum distance of 1.2mm for reinforced insulation for working volgage up to 250V on coated PCBs. Regards, Tom -------------------------------------------------- Tomonori Sato <vef00...@nifty.ne.jp> URL: http://member.nifty.ne.jp/tsato/ ------------------------------------------- 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"