Brad, The boards are manufactured to BS and IPC recommendations by a high volume international supplier if there are any problems with the plating, ( of which there is no evidence and which I doubt there are), then its not our problem.
As for the latest on the actual problem - board warping to well within IPC recomendations but outside of what we'd like, it seems that the latest boards have even less of a problem. Its not gone away, and we are still working on a better resolution, but for now we've decided to just run with them and see what the best and worst look like. Thanks for all your help, Jason. -----Original Message----- From: Brad Velander [mailto:[EMAIL PROTECTED]] Sent: 11 April 2002 16:41 To: 'Protel EDA Forum' Subject: Re: [PEDA] WANTED: PCB Expert (Off Topic) Jason, aside from your problems with warp and twist, there are other possible problems lurking if you do not know the actual thickness of your Nickel/Gold plating. There are a myriad of complicated electro/chemical/physics related problems which can occur with Nickel Gold plating, the most common of which is solder joint embrittlement. SN/PB/AU Solder joint embrittlement can cause solder joint failures in field units which are a devil to find because they will break connections during thermal or stress cycles and be fine other times. In conjunction with your warping, your design would be a prime candidate for these failures. In the extreme cases I have been told of boards having significant numbers of their components drop off the boards when the board is manually flexed. On a typical SMD land pattern design if your Gold is greater then approx. 25 - 30 microinches then you may have embrittlement problems if you do not use special solder compositions. I would suggest that you must find out what the nickel & gold plating thickness is for your board. Then you could discuss them here with us and we could give you some more detailed information. In the future you should specify the gold plating requirements and not rely on luck or a single fabricators judgement as to what plating thickness your require for your board. One of the best studies which I have found on this issue was performed by HP. The article was titled "Effect of AU on the Reliability of Fine Pitch Surface Mount Solder Joints" by Judith Glazer, HP, Palo Alto, California. It was published in "Proceedings, Surface Mount International Conference, Aug 25 - 29 (1991), San Jose, CA." It was republished in Circuit World 18, pg 41-46 1992 and Surface Mount Technology 4, pgs 15 - 28 (1992). Good luck Jason. Sincerely, Brad Velander. Lead PCB Designer Norsat International Inc. Microwave Products Tel (604) 292-9089 (direct line) Fax (604) 292-9010 email: [EMAIL PROTECTED] http://www.norsat.com See us at Booth S8155 at NAB 2002 in Las Vegas April 8 - 11. > -----Original Message----- > From: Jason Morgan [mailto:[EMAIL PROTECTED]] > Sent: Thursday, April 11, 2002 1:10 AM > To: 'Protel EDA Forum' > Subject: Re: [PEDA] WANTED: PCB Expert (Off Topic) > > > Monitoring - sort of, bit busy for full followup. > > Anyway, I did post a full explanation that the plating would > be Cu+Ni+Au, no > idea on the proportions. > > J. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[email protected] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
