----------------------------------------- Stay ahead of the information curve. Receive PCB news and jobs on your desktop daily. Subscribe today to the PCB CafeNews newsletter. [ http://www10.pcbcafe.com/nl/newsletter_subscribe.php ] It's informative and essential. This message was sent to you from a machine at 192.35.156.11 -- Attached file included as plaintext by Ecartis -- -- File: Re: [SI-LIST] Re: Cross-hatched reference planes.eml Received: from 192.35.156.11 (SquirrelMail authenticated user cadpro2k) by cafemail.pcbcafe.com with HTTP; Wed, 4 Apr 2007 10:43:01 -0700 (PDT) Message-ID: <13632.192.35.156.11.1175708581.squirrel@xxxxxxxxxxxxxxxxxxxx> In-Reply-To: <380-22007434155153515@xxxxxxxxxxxxx> References: <380-22007434155153515@xxxxxxxxxxxxx> Date: Wed, 4 Apr 2007 10:43:01 -0700 (PDT) Subject: Re: [SI-LIST] Re: Cross-hatched reference planes From: "Mitch S. Morey" <cadpro2k@xxxxxxxxxx> To: leeritchey@xxxxxxxxxxxxx User-Agent: SquirrelMail/1.4.2 MIME-Version: 1.0 Content-Type: text/plain;charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Priority: 3 Importance: Normal And another response comes to mind when you get back to original question of "Cross-Hatched" and "Reference Planes" If you imply reference planes to be impedance associated reference planes, then: "Cross-Hatched Reference Planes equal disaster." If they are simply cross hatched power planes, that's a different matter. Still, like Lee mentions, with PCBs very select (few) cases are warranted. Good day. Mitch > > Jeff, > > I agree that there are a few exotic places where laminate to laminate > bonding is needed and is accomplished using cross hatching as well as in > flex circuits to improve flexibility, which I think was the original > question. > > I responded the way I did because there are still those who want to see > this done to ordinary PCBs made from copper and FR4 class resins, where it > was needed long ago. I did several designs this way just to prevent > delaminataion. The industry fixed this problem long ago. > > I don't think there is much to debate here. My goal was to make sure that > this old sock did not creep back into standard multilayer board design. > And, yes, this is often necessary in multilayer ceramic IC packages. > > Lee Ritchey > > >> [Original Message] >> From: Jeff Seeger <jseeger@xxxxxxxxxxxxxx> >> To: <leeritchey@xxxxxxxxxxxxx> >> Cc: <si-list@xxxxxxxxxxxxx> >> Date: 4/4/2007 8:27:09 AM >> Subject: Re: [SI-LIST] Re: Cross-hatched reference planes >> >> Lee Ritchey wrote: >> >> >All of those reasons, except the flex circuit one, went by the wayside > many >> >years ago. Wonder why they still linger around the industry like old > socks! >> > >> Agreed venting and bonding concerns first appeared in 60s military >> specs but I'll wager that if you were to chat up a substrate foundry >> there is current call for venting. >> >> On the bonding front we were recently asked to provide some "hatch", >> understood to be for laminate to laminate, in an area of a board >> lacking vias. The board involved fussy materials and a challenging >> end-use environment. I don't believe it was an offhanded request. >> >> We'll simply have to agree to disagree on cross hatching as a way >> to work with supply- and signal- dense areas to minimize the layer >> count *and* bow and twist. >> >> I'd be happy to debate further but suggest IPC's Technet as a more >> appropriate forum for the bandwidth on DFM issues. Old socks can >> become new again, it can be useful to recall where we put them. >> >> Respectfully, >> >> -- >> >> Jeff Seeger Applied CAD Knowledge Inc >> Chief Technical Officer Tyngsboro, MA 01879 >> jseeger "at" appliedcad "dot" com 978 649 9800 > > > ------------------------------------------------------------------ > To unsubscribe from si-list: > si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field > > or to administer your membership from a web page, go to: > //www.freelists.org/webpage/si-list > > For help: > si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > > > List technical documents are available at: > http://www.si-list.net > > List archives are viewable at: > //www.freelists.org/archives/si-list > or at our remote archives: > http://groups.yahoo.com/group/si-list/messages > Old (prior to June 6, 2001) list archives are viewable at: > http://www.qsl.net/wb6tpu > > > ----------------------------------------- Stay ahead of the information curve. Receive PCB news and jobs on your desktop daily. Subscribe today to the PCB CafeNews newsletter. [ http://www10.pcbcafe.com/nl/newsletter_subscribe.php ] It's informative and essential. This message was sent to you from a machine at 192.35.156.11 ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List technical documents are available at: http://www.si-list.net List archives are viewable at: //www.freelists.org/archives/si-list or at our remote archives: http://groups.yahoo.com/group/si-list/messages Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu