Roger - What is the lead frame material? Just a guess, but I would be willing to bet it is Invar or Alloy 42 and the solderability is degraded due to age. Jeffrey A McGlaughlin, CID Engineering Designer Battelle Memorial Institute Columbus Ohio http://www.battelle.org [log in to unmask] -----Original Message----- From: Roger Stoops [mailto:[log in to unmask]] Sent: Thursday, January 06, 2005 3:12 PM To: [log in to unmask] Subject: Re: [TN] Solder Joint Failures after Short-term Vibration Ah, now this is something to think about... The grainy appearance of the leads is the first thing that drew my attention. However, these same parts are used on other assemblies with no apparent problems (but I will ask about potential lead plating/contamination problems). And 1) There are micro-voids in the solder joints. According to 610C, up to 25% voiding of BGA ball to board interface is process indicator but can be accepted. But our vendor is telling us they are passing anything under 50% (minus any area of lead not on land) total area , per 610C section 12.2.5.3 (pg. 12-45). Anyone know or have experience with how this relates to non-BGA joints? 2) Pads are about a mil [.025mm] wider than lead. (Never been a problem before, but...) And we are not seeing full height toe fillets; in fact, some toe fillets are less than 50% of the lead height. Roger -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Paul Edwards Sent: Thursday, January 06, 2005 2:49 PM To: [log in to unmask] Subject: Re: [TN] Solder Joint Failures after Short-term Vibration Roger, It almost sounds like you have a QFP lead plating problem.... The EMS is probably right and these meet the spec... However for your application IPC is not enough... The reason the top of the lead is grainy is because that is the reflowed condition of the QFP plating... I would guess that 1) If x-rayed you have micro-voids in the solder under the leads 2) Your pads are the same width as the leads on the QFPs for the failing lot You need to get full height toe fillets on the QFP leads...otherwise they will fail... It is possible to do but requires secondary operations... Paul Paul Edwards Process Engineering [log in to unmask] Tel: 408-433-4700 FAX: 408-433-9988 Surface Art Engineering 81Bonaventura Dr. San Jose, CA 95134 DUNS: 944740570 CAGE/NCAGE: 1XZ48 -----Original Message----- From: Roger Stoops [mailto:[log in to unmask]] Sent: Thursday, January 06, 2005 10:19 AM To: [log in to unmask] Subject: [TN] Solder Joint Failures after Short-term Vibration Hello all, We are having an ongoing problem with solder joint failures on a 144-pin PQFP processor, after short-term vibration. The board layout and mechanical mounting apparatus were designed with vibration in mind, and have passed vibration testing in the past. The same processor is used on a dozen other assemblies, none of which have this problem. The solder joints appear to exhibit dewetting, although there is a toe and heel fillet. The heel fillet is unusually large, and the top of the PQFP lead has a grainy appearance instead of a matte or shiny appearance. Some leads can be pushed off the solder joint with very little pressure. Sn62Pb36Ag2 solder is being used, and our EMS provider continues to claim that boards meet IPC-A-610 class 2 requirements. Any ideas as to what may be causing solder joint failures? Also, any suggestions or recommendations (preferred) for a test house to provide x-ray, microsection and composition analysis? TIA & Best Regards, Roger M. Stoops, CID+ Trimble Navigation Ltd., Dayton, OH, USA Ph: +01 937.245.5288 Fax: +01 937.233.7511 Oh, and BTW, changing EMS providers is not an option... --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------