Message-ID: <3B5FE00D.A23F6E36@algor.co.uk> From: Rick Filipkiewicz X-Mailer: Mozilla 4.75 [en] (WinNT; U) X-Accept-Language: en MIME-Version: 1.0 Newsgroups: comp.arch.fpga Subject: PQFP sockets Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Organization: Algorithmics Ltd. Cache-Post-Path: mudchute.algor.co.uk!root@oval.algor.co.uk X-Cache: nntpcache 2.4.0b2 (see http://www.nntpcache.org/) Lines: 14 Date: Thu, 26 Jul 2001 10:17:01 +0100 NNTP-Posting-Host: 62.254.210.251 X-Complaints-To: abuse@ntlworld.com X-Trace: news6-win.server.ntlworld.com 996139023 62.254.210.251 (Thu, 26 Jul 2001 10:17:03 BST) NNTP-Posting-Date: Thu, 26 Jul 2001 10:17:03 BST Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news.ifi.unizh.ch!news.imp.ch!psinet-eu-nl!newsfeeds.belnet.be!news.belnet.be!colt.net!newspeer.clara.net!news.clara.net!news5-gui.server.ntli.net!ntli.net!news6-win.server.ntlworld.com.POSTED!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:8510 I know this is a bit off topic but there's a lot of general h/w expertise in this NG so here goes: What's the general view of PQFP sockets that mount on the same SMT footprint as the component itself ? o As test sockets ? o For production ? My experience of these this things is that they are as flakey as a bad case of dandruff but maybe there are better ones than those I've had to deal with. If so which ones are best ? ###### From: Greg Neff Newsgroups: comp.arch.fpga Subject: Re: PQFP sockets Date: Thu, 26 Jul 2001 10:03:10 -0400 Organization: Microsym Computers Inc. Lines: 35 Message-ID: References: <3B5FE00D.A23F6E36@algor.co.uk> NNTP-Posting-Host: hil-qbu-ptr-vty8.as.wcom.net Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Trace: suaar1aa.prod.compuserve.com 996156126 314 206.175.109.8 (26 Jul 2001 14:02:06 GMT) X-Complaints-To: newsmaster@compuserve.com NNTP-Posting-Date: 26 Jul 2001 14:02:06 GMT X-Newsreader: Forte Agent 1.8/32.548 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news.ifi.unizh.ch!news.imp.ch!news.stealth.net!news-east.rr.com!portc01.blue.aol.com!news.compuserve.com!news-master.compuserve.com!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:8544 On Thu, 26 Jul 2001 10:17:01 +0100, Rick Filipkiewicz wrote: >I know this is a bit off topic but there's a lot of general h/w >expertise in this NG so here goes: > >What's the general view of PQFP sockets that mount on the same SMT >footprint as the component itself ? > >o As test sockets ? > >o For production ? > >My experience of these this things is that they are as flakey as a bad >case of dandruff but maybe there are better ones than those I've had to >deal with. If so which ones are best ? I don't know about surface mount PQFP sockets. The only PQFP test sockets that we have used are Yamaichi through-hole clam shells: http://www.yeu.com/index_tb.html These have worked fairly well for us. The only place we have used these is on engineering evaluation boards to qualify ASICs in place of FPGAs. I would not use these in production. I don't even like socketing QFPs for programming (we use in-circuit programming). Why would you want to socket a PQFP on a production board? =================================== Greg Neff VP Engineering *Microsym* Computers Inc. greg@guesswhichwordgoeshere.com ###### Message-ID: <3B606568.43A71310@algor.co.uk> From: Rick Filipkiewicz X-Mailer: Mozilla 4.75 [en] (WinNT; U) X-Accept-Language: en MIME-Version: 1.0 Newsgroups: comp.arch.fpga Subject: Re: PQFP sockets References: <3B5FE00D.A23F6E36@algor.co.uk> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Organization: Algorithmics Ltd. Cache-Post-Path: mudchute.algor.co.uk!root@oval.algor.co.uk X-Cache: nntpcache 2.4.0b2 (see http://www.nntpcache.org/) Lines: 37 Date: Thu, 26 Jul 2001 19:46:00 +0100 NNTP-Posting-Host: 62.254.210.251 X-Complaints-To: abuse@ntlworld.com X-Trace: news6-win.server.ntlworld.com 996173163 62.254.210.251 (Thu, 26 Jul 2001 19:46:03 BST) NNTP-Posting-Date: Thu, 26 Jul 2001 19:46:03 BST Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!pinatubo.switch.ch!newsfeeds.belnet.be!news.belnet.be!news1.ebone.net!news.ebone.net!diablo.netcom.net.uk!netcom.net.uk!dispose.news.demon.net!demon!btnet-peer0!btnet!news5-gui.server.ntli.net!ntli.net!news6-win.server.ntlworld.com.POSTED!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:8547 Greg Neff wrote: > On Thu, 26 Jul 2001 10:17:01 +0100, Rick Filipkiewicz > wrote: > > >I know this is a bit off topic but there's a lot of general h/w > >expertise in this NG so here goes: > > > >What's the general view of PQFP sockets that mount on the same SMT > >footprint as the component itself ? > > > >o As test sockets ? > > > >o For production ? > > > >My experience of these this things is that they are as flakey as a bad > >case of dandruff but maybe there are better ones than those I've had to > >deal with. If so which ones are best ? > > I don't know about surface mount PQFP sockets. The only PQFP test > sockets that we have used are Yamaichi through-hole clam shells: > > http://www.yeu.com/index_tb.html > > These have worked fairly well for us. The only place we have used > these is on engineering evaluation boards to qualify ASICs in place of > FPGAs. I would not use these in production. I don't even like > socketing QFPs for programming (we use in-circuit programming). Why > would you want to socket a PQFP on a production board? I don't. I'm trying to convince one of my colleagues that SMT QFP sockets come in the ``Don't go there'' [I'd put it more strongly - ``Don't even walk past there''] category or, failing that, to come up with the least unreliable one. ###### From: "Speedy Zero Two" Newsgroups: comp.arch.fpga Subject: Re: PQFP sockets Date: Thu, 26 Jul 2001 21:44:54 +0100 Lines: 56 Message-ID: <9jpv7k$900$1@news5.svr.pol.co.uk> References: <3B5FE00D.A23F6E36@algor.co.uk> <3B606568.43A71310@algor.co.uk> NNTP-Posting-Host: modem-875.articuno.dialup.pol.co.uk X-Trace: news5.svr.pol.co.uk 996180020 9216 217.135.23.107 (26 Jul 2001 20:40:20 GMT) NNTP-Posting-Date: 26 Jul 2001 20:40:20 GMT X-Complaints-To: abuse@theplanet.net X-Priority: 3 X-MSMail-Priority: Normal X-Newsreader: Microsoft Outlook Express 5.00.2919.6600 X-MimeOLE: Produced By Microsoft MimeOLE V5.00.2919.6600 Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news.ifi.unizh.ch!news.imp.ch!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!diablo.theplanet.net!news.theplanet.net!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:8560 Hi Rick, Putting IC's in sockets is generally a bad idea. The faster you want you logic to run the more problems you will have. Lead inductance is a major headache, decoupling the power supply can be a real problem! Hope this helps your cause. Dave <--Just putting something back into the system--> ---------------------------------------------------------- "Rick Filipkiewicz" wrote in message news:3B606568.43A71310@algor.co.uk... > > > Greg Neff wrote: > > > On Thu, 26 Jul 2001 10:17:01 +0100, Rick Filipkiewicz > > wrote: > > > > >I know this is a bit off topic but there's a lot of general h/w > > >expertise in this NG so here goes: > > > > > >What's the general view of PQFP sockets that mount on the same SMT > > >footprint as the component itself ? > > > > > >o As test sockets ? > > > > > >o For production ? > > > > > >My experience of these this things is that they are as flakey as a bad > > >case of dandruff but maybe there are better ones than those I've had to > > >deal with. If so which ones are best ? > > > > I don't know about surface mount PQFP sockets. The only PQFP test > > sockets that we have used are Yamaichi through-hole clam shells: > > > > http://www.yeu.com/index_tb.html > > > > These have worked fairly well for us. The only place we have used > > these is on engineering evaluation boards to qualify ASICs in place of > > FPGAs. I would not use these in production. I don't even like > > socketing QFPs for programming (we use in-circuit programming). Why > > would you want to socket a PQFP on a production board? > > I don't. I'm trying to convince one of my colleagues that SMT QFP sockets > come in the ``Don't go there'' [I'd put it more strongly - ``Don't even walk > past there''] category or, failing that, to come up with the least > unreliable one. > ###### Message-ID: <3B60B2C4.A4B735D@algor.co.uk> From: Rick Filipkiewicz X-Mailer: Mozilla 4.75 [en] (WinNT; U) X-Accept-Language: en MIME-Version: 1.0 Newsgroups: comp.arch.fpga Subject: Re: PQFP sockets References: <3B5FE00D.A23F6E36@algor.co.uk> <3B606568.43A71310@algor.co.uk> <9jpv7k$900$1@news5.svr.pol.co.uk> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Organization: Algorithmics Ltd. Cache-Post-Path: mudchute.algor.co.uk!root@oval.algor.co.uk X-Cache: nntpcache 2.4.0b2 (see http://www.nntpcache.org/) Lines: 33 Date: Fri, 27 Jul 2001 01:16:04 +0100 NNTP-Posting-Host: 62.254.210.251 X-Complaints-To: abuse@ntlworld.com X-Trace: news6-win.server.ntlworld.com 996192966 62.254.210.251 (Fri, 27 Jul 2001 01:16:06 BST) NNTP-Posting-Date: Fri, 27 Jul 2001 01:16:06 BST Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news.ifi.unizh.ch!news.imp.ch!fr.clara.net!heighliner.fr.clara.net!isdnet!195.200.0.51.MISMATCH!shale.ftech.net!news.ftech.net!newspeer.clara.net!news.clara.net!news5-gui.server.ntli.net!ntli.net!news6-win.server.ntlworld.com.POSTED!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:8548 Speedy Zero Two wrote: > Hi Rick, > > Putting IC's in sockets is generally a bad idea. The faster you want you > logic to run the more problems you will have. > > Lead inductance is a major headache, decoupling the power supply can be a > real problem! > > Hope this helps your cause. > > Dave > <--Just putting something back into the system--> > I'm more worried that I won't even get to these problems because the physical issues, i.e. soldering, will kill me first. The part being considered has its leads underneath the socket plastic and its a 208QFP so any open or short is going to be *HARD* to fix. There's a plastic frame inside the socket at the bottom that could be removed for access but my experience with PLCC sockets tells me that once you've done this its very difficult to get the chip to seat properly. The other class of SMT socket I've seen looks more like a normal chip but the leads have been extended downwards & the socket sits up off the board. The killer with these is that wicking can lead to shorts behind the wall of IC pins which are impossible to fix.