I think your correct, but any component even passives have lower MTBF's than just copper over FR-4 (although the Printed circuit assemblies do have MTBF figures). Since the backplane is a huge hit time wise to repair or replace you would like to avoid any reason to have to do that if possible. Although I was thinking about the use of the daughter boards mentioned by someone. The connectors that are needed to attach the mid-plane adds some unreliability right back into the system. Less I would think than the a few part count passives but it still is heading in the wrong direction from a reliability standpoint. Gary (If cards are on both sides I believe its more correct to call it a mid-plane rather than backplane)
From: Grasso, Charles [mailto:charles.gra...@echostar.com] Sent: Thursday, February 05, 2004 2:58 PM To: 'John Woodgate'; 'emc-p...@majordomo.ieee.org' Subject: RE: Should Backplanes be passive? I thought the original poster was asking about power filters on the backplane?? Best Regards Charles Grasso Senior Compliance Engineer Echostar Communications Corp. Tel: 303-706-5467 Fax: 303-799-6222 Cell: 303-204-2974 Email: charles.gra...@echostar.com; Email Alternate: chasgra...@ieee.org From: John Woodgate [mailto:j...@jmwa.demon.co.uk] Sent: Thursday, February 05, 2004 1:56 PM To: emc-p...@majordomo.ieee.org Subject: Re: Should Backplanes be passive? I read in !emc-pstc that David Heald <hea...@symbol.com> wrote (in <s0224346....@symbol.com>) about 'Should Backplanes be passive?' on Thu, 5 Feb 2004: >We designed the >backplane from the get-go to accept rear daughtercards for EMI filters, >I/O cables/filters, and the like. This allowed for easy replacement, >re-work, and redesign of filters and active circuits when needed That's the way to do it! The backplane is often a *good* place electrically to put EMC filters but that conflicts with the reliability requirements. The daughter card solution satisfies both. -- Regards, John Woodgate, OOO - Own Opinions Only. The good news is that nothing is compulsory. The bad news is that everything is prohibited. http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ 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: emc_p...@symbol.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://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ 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: emc_p...@symbol.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://www.ieeecommunities.org/emc-pstc This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ieee-pses.org/ 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: emc_p...@symbol.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://www.ieeecommunities.org/emc-pstc
