Hmmm, good question. First thought is that it provides for a good toe/heel fillet which I guess depending on the lead style is where a good portion of the solder joint strength comes from. Maybe something to do with the surface tension of Pb-free solders? Other than that...? Anyone from the (1-13) Surface Mount Land Patterns Subcommittee listening? Roger -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Brooks,Bill Sent: Tuesday, November 16, 2004 1:39 PM To: [log in to unmask] Subject: Re: [TN] SOD323 problem... I added your pattern to the web page ... interesting how the PCB libraries one is so long and skinny... any advantage in that? I posted it on my website for comments... http://pcbwizards.com/faq.htm Best regards, Bill Brooks - KG6VVP PCB Design Engineer , C.I.D.+, C.I.I. Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510 e-mail:[log in to unmask] http://www.dtwc.com http://pcbwizards.com -----Original Message----- From: Roger Stoops [mailto:[log in to unmask]] Sent: Tuesday, November 16, 2004 9:56 AM To: TechNet E-Mail Forum; Brooks,Bill; Steve Gregory Subject: RE: [TN] SOD323 problem... Okay, I misread the package type, thought it was a SOD123. But we still have had no problems (yet) with the 323. Used the latest version of the PCBLibraries calculator to derive the "latest" land pattern for the SOD-323, and the calc says 1.4x.5mm lands on 2.2mm center (3.6mm overall length). Sent a pdf file with what the calculator came up with. For $57US, the calculator is a pretty good buy, takes a lot of guesswork out and meets IPC-735x standard. (http://www.pcblibraries.com) Attachment sent to Bill and Steve, maybe Steve could put it on his website for comments? More Regards and some apologies too, Roger "Want to see how dumb a dummy can be? Look no further, just look at me." -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Brooks,Bill Sent: Tuesday, November 16, 2004 11:44 AM To: [log in to unmask] Subject: Re: [TN] SOD323 problem... The part we are using is defined on this spec sheet... http://www.protekdevices.com/datasheets/gblc.pdf The recommended pads are 0.8mm square and 3.0mm at the extreme dimension from outside edge to outside edge of the pads. I don't see any reference to this package in the IPC-SM-782. What sort of geometries are you dealing with Steve? Best regards, Bill Brooks - KG6VVP PCB Design Engineer , C.I.D.+, C.I.I. Tel: (760)597-1500 Ext 3772 Fax: (760)597-1510 e-mail:[log in to unmask] http://www.dtwc.com http://pcbwizards.com -----Original Message----- From: Werner Engelmaier [mailto:[log in to unmask]] Sent: Tuesday, November 16, 2004 6:40 AM To: [log in to unmask] Subject: Re: [TN] SOD323 problem... Hi Bill, The immediate fix is to make the pads larger. The real problem is a larger CTE mismatch between the SOD323 and the PCB, and thoise leads do not even deserve to be called leads--zero compliancy. These 'leads' need to be turned UNDER the component body to decrease the DNP. BUT, neither of these steps assures a solution--it may simply move the failure mode from ripped-out pads to fractured solder attachments. The real solution is to turn the component upside-down and provide it with longer compliant leads; no sacrifice in real estate.. Regards, Werner Engelmaier Engelmaier Associates, L.C. Electronic Packaging, Interconnection and Reliability Consulting 7 Jasmine Run Ormond Beach, FL 32174 USA Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904 E-mail: [log in to unmask], Website: www.engelmaier.com --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------