PCI Brackets Problems
Rick, I have a similar experience with PCI card cage brackets. This architecture was never intended for today's environment. We have used various gasketing techniques. Some OEMs now include clips on the chassis to aid in the electrical seal with the card bracket. A.K. Stamping has a patent on one add-on gasket (US 5,856,632). The first problems we found were with ESD testing, not radiated EMI. Now, we have seen problems with both. Even a gasketed PCI card cage is mediocre as a shielded enclosure. Regards, Jim Jim Knighten, Ph.D. Teradata, a Division of NCR http://www.ncr.com <http://www.ncr.com> 17095 Via Del Campo San Diego, CA 92127 USA Tel: 858-485-2537 Fax: 858-485-3788 jim.knigh...@ncr.com <mailto:jim.knigh...@ncr.com> -Original Message- From: rbus...@es.com <mailto:rbus...@es.com> [mailto:rbus...@es.com] <mailto:[mailto:rbus...@es.com]> Sent: Friday, August 30, 2002 7:54 AM To: emc-p...@majordomo.ieee.org <mailto:emc-p...@majordomo.ieee.org> Subject:PCI Brackets Problems I am fighting the age old problem of PCI brackets on various PC chassis not making adequate electrical contact. Aperture leaks, especially at high frequencies, is a continual problem, to say nothing about the flimsy construction of the brackets. Has anyone had any success with the clips, gaskets and other EMI solutions? If you have any suggestions on types, or manufacturers please let me know. Thanks in advance... Rick Busche Evans & Sutherland rbus...@es.com <mailto:rbus...@es.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/ <http://www.ewh.ieee.org/soc/emcs/pstc/> To cancel your subscription, send mail to: majord...@ieee.org <mailto:majord...@ieee.org> with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com <mailto:emc-p...@hypercom.com> Dave Heald: davehe...@attbi.com <mailto:davehe...@attbi.com> For policy questions, send mail to: Richard Nute: ri...@ieee.org <mailto:ri...@ieee.org> Jim Bacher: j.bac...@ieee.org <mailto:j.bac...@ieee.org> All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ <http://ieeepstc.mindcruiser.com/> Click on "browse" and then "emc-pstc mailing list" Jim Knighten, Ph.D. Teradata, a Division of NCR http://www.ncr.com 17095 Via Del Campo San Diego, CA 92127 USA Tel: 858-485-2537 Fax: 858-485-3788 jim.knigh...@ncr.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: 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"
Re: PCI Brackets Problems
Beware that stainless steel has high impedance in GHz range, about 50 times higher than copper. That seriously degrades performance at high frequencies relative to BeCu or other good conductors. Neven > > Rick, > > Chomerics' Springline product line is an off-the-shelf solution: > > http://www.chomerics.com/products/cardcage.htm > > The spring-fingers on these one-piece gaskets are formed > toward the rear panel instead of toward the inside, where > damage due to snagging can be a problem. > > The only negative comment I have about this product concerns > the stainless steel material. In my experience, mixing stainless steel > and cold-rolled steel causes corrosion, even though the CRS is Zinc-plated. > Chomerics has offered to tin-plate the SS for us. > > Over the years, the design group I'm in has tried various > custom gaskets for this application--strips of tin-plated Be/Cu > or Phosphor-Bronze spring fingers between the PCI brackets > or fabric-over-foam gaskets, both of which have their > challenges. It seems we've come full-circle and have settled > on the above off-the-shelf solution. > > Good Luck, > Dan > > > X-MimeOLE: Produced By Microsoft Exchange V6.0.5762.3 > > content-class: urn:content-classes:message > > MIME-Version: 1.0 > > Subject: PCI Brackets Problems > > Date: Fri, 30 Aug 2002 08:54:09 -0600 > > X-MS-Has-Attach: > > X-MS-TNEF-Correlator: > > Thread-Topic: Curious about Tripp-Lite "isolation transformer" > > Thread-Index: AcJQM3jmO5hzvAL2Sl+Op3k/hH61TAAAMcqg > > From: > > To: > > Content-Transfer-Encoding: 8bit > > X-MIME-Autoconverted: from quoted-printable to 8bit by ruebert.ieee.org id > g7UEsCC20318 > > X-Resent-To: Multiple Recipients > > X-Listname: emc-pstc > > X-Info: Help requests to emc-pstc-requ...@majordomo.ieee.org > > X-Info: [Un]Subscribe requests to majord...@majordomo.ieee.org > > X-Moderator-Address: emc-pstc-appro...@majordomo.ieee.org > > > > > > I am fighting the age old problem of PCI brackets on various PC chassis not > making adequate electrical contact. Aperture leaks, especially at high > frequencies, is a continual problem, to say nothing about the flimsy > construction of the brackets. Has anyone had any success with the clips, > gaskets > and other EMI solutions? If you have any suggestions on types, or > manufacturers > please let me know. > > > > Thanks in advance... > > > > Rick Busche > > Evans & Sutherland > > rbus...@es.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: > > 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" --- 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"
Re: PCI Brackets Problems
Rick, Chomerics' Springline product line is an off-the-shelf solution: http://www.chomerics.com/products/cardcage.htm The spring-fingers on these one-piece gaskets are formed toward the rear panel instead of toward the inside, where damage due to snagging can be a problem. The only negative comment I have about this product concerns the stainless steel material. In my experience, mixing stainless steel and cold-rolled steel causes corrosion, even though the CRS is Zinc-plated. Chomerics has offered to tin-plate the SS for us. Over the years, the design group I'm in has tried various custom gaskets for this application--strips of tin-plated Be/Cu or Phosphor-Bronze spring fingers between the PCI brackets or fabric-over-foam gaskets, both of which have their challenges. It seems we've come full-circle and have settled on the above off-the-shelf solution. Good Luck, Dan > X-MimeOLE: Produced By Microsoft Exchange V6.0.5762.3 > content-class: urn:content-classes:message > MIME-Version: 1.0 > Subject: PCI Brackets Problems > Date: Fri, 30 Aug 2002 08:54:09 -0600 > X-MS-Has-Attach: > X-MS-TNEF-Correlator: > Thread-Topic: Curious about Tripp-Lite "isolation transformer" > Thread-Index: AcJQM3jmO5hzvAL2Sl+Op3k/hH61TAAAMcqg > From: > To: > Content-Transfer-Encoding: 8bit > X-MIME-Autoconverted: from quoted-printable to 8bit by ruebert.ieee.org id g7UEsCC20318 > X-Resent-To: Multiple Recipients > X-Listname: emc-pstc > X-Info: Help requests to emc-pstc-requ...@majordomo.ieee.org > X-Info: [Un]Subscribe requests to majord...@majordomo.ieee.org > X-Moderator-Address: emc-pstc-appro...@majordomo.ieee.org > > > I am fighting the age old problem of PCI brackets on various PC chassis not making adequate electrical contact. Aperture leaks, especially at high frequencies, is a continual problem, to say nothing about the flimsy construction of the brackets. Has anyone had any success with the clips, gaskets and other EMI solutions? If you have any suggestions on types, or manufacturers please let me know. > > Thanks in advance... > > Rick Busche > Evans & Sutherland > rbus...@es.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: > 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"
RE: PCI Brackets Problems
Oooops, my reply was really relevant to Compact PCI panels, not PCI. Sorry, I just realized it. I haven't worked on designs using PCI brackets for EMC. I believe that former Instrument Specielties, now part of Laird Technologies, can help you. They are very knowledgeable in the area of shielding/gasketing, one of the best resources, and have many products for that. Neven > > Yup, we had the same problem on a GNIC card. We made the card and its > L-shaped bracket. The card was intended for any ol' computer. The casual > contact > between the face of the bracket and the PC chassis was "iffy" at best. I put > a > couple of small dimples (punched slots really), on the long sides of the > bracket. They were on both sides of the bracket and spaced equidistant from > the > top and bottom of the opening in the PC's card mounting bracket. The dimples > made contact just before the end of the GNIC bracket aligned with the screw > hole > in the PC mounting bracket. This gave me enough force to make electrical > grounding contact, and effectively cut the card opening size by 1/3. Yes, it > does leave small slots between dimples, but these slots are significantly > smaller than the slots that are left unintentionally between the card and the > PC > mounting bracket. The GNIC, at the time, had a very noisy 1 X 9 laser > transceiver running at 1.25 GHz and this resolved my problem. The arrang! > ement ended up being tested multiple times because of changes in > transceivers, > and other circuit changes but I never had any more problems with the fit. > > Gary > > -Original Message- > From: rbus...@es.com [mailto:rbus...@es.com] > Sent: Friday, August 30, 2002 7:54 AM > To: emc-p...@majordomo.ieee.org > Subject: PCI Brackets Problems > > > > I am fighting the age old problem of PCI brackets on various PC chassis not > making adequate electrical contact. Aperture leaks, especially at high > frequencies, is a continual problem, to say nothing about the flimsy > construction of the brackets. Has anyone had any success with the clips, > gaskets > and other EMI solutions? If you have any suggestions on types, or > manufacturers > please let me know. > > Thanks in advance... > > Rick Busche > Evans & Sutherland > rbus...@es.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: > 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" --- 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"
Re: PCI Brackets Problems
There are several types of gaskets. The ones with a continuous ridge along the centerline (inverted V-shape) are not compliant thus they can leave slots and cause difficulties with board insertion. The spiral gaskets make good contact but tend to kink, get caught and fall out of the groove in the panels. The best ones have a series of rounded clip- like "fingers" along the gasket, allowing each individual contact to comply with the size/shape between two panels. Regarding material, you want to use (plated) beryllium copper. I think the kind that is best is thermally treated after it has been formed. Unfortunately the standard panels are aluminum, which is not best material regarding developing contact resistance to a different gasket material over time, due to galvanic effect/corrosion. Neven > > I am fighting the age old problem of PCI brackets on various PC chassis not > making adequate electrical contact. Aperture leaks, especially at high > frequencies, is a continual problem, to say nothing about the flimsy > construction of the brackets. Has anyone had any success with the clips, > gaskets > and other EMI solutions? If you have any suggestions on types, or > manufacturers > please let me know. > > Thanks in advance... > > Rick Busche > Evans & Sutherland > rbus...@es.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: > 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"
RE: PCI Brackets Problems
Yup, we had the same problem on a GNIC card. We made the card and its L-shaped bracket. The card was intended for any ol' computer. The casual contact between the face of the bracket and the PC chassis was "iffy" at best. I put a couple of small dimples (punched slots really), on the long sides of the bracket. They were on both sides of the bracket and spaced equidistant from the top and bottom of the opening in the PC's card mounting bracket. The dimples made contact just before the end of the GNIC bracket aligned with the screw hole in the PC mounting bracket. This gave me enough force to make electrical grounding contact, and effectively cut the card opening size by 1/3. Yes, it does leave small slots between dimples, but these slots are significantly smaller than the slots that are left unintentionally between the card and the PC mounting bracket. The GNIC, at the time, had a very noisy 1 X 9 laser transceiver running at 1.25 GHz and this resolved my problem. The arrang! ement ended up being tested multiple times because of changes in transceivers, and other circuit changes but I never had any more problems with the fit. Gary -Original Message- From: rbus...@es.com [mailto:rbus...@es.com] Sent: Friday, August 30, 2002 7:54 AM To: emc-p...@majordomo.ieee.org Subject: PCI Brackets Problems I am fighting the age old problem of PCI brackets on various PC chassis not making adequate electrical contact. Aperture leaks, especially at high frequencies, is a continual problem, to say nothing about the flimsy construction of the brackets. Has anyone had any success with the clips, gaskets and other EMI solutions? If you have any suggestions on types, or manufacturers please let me know. Thanks in advance... Rick Busche Evans & Sutherland rbus...@es.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: 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"
PCI Brackets Problems
I am fighting the age old problem of PCI brackets on various PC chassis not making adequate electrical contact. Aperture leaks, especially at high frequencies, is a continual problem, to say nothing about the flimsy construction of the brackets. Has anyone had any success with the clips, gaskets and other EMI solutions? If you have any suggestions on types, or manufacturers please let me know. Thanks in advance... Rick Busche Evans & Sutherland rbus...@es.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: 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"
