Sorry, we had noticed this oddity while prepping the board to replace a BGA that had been removed because it wasn't functioning properly and were wondering what the cause of the oddity might be. But we need the board so they are proceeding with the rework to replace the BGA. Likely all the lands are wick'd off by now. Seeing this on one BGA location after removal - any thoughts on what reliability risks might be present on other parts of this board? Or would you think this is most likely a result of the heat from the removal operation? -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of vladimir Igoshev Sent: June 1, 2010 11:46 AM To: [log in to unmask] Subject: Re: [TN] Crystalline solder balls Genny, You can send them to me, so I can take SEM images. Regards, Vladimir SENTEC Testing Laboratory Inc. 11 Canadian Road, Unit 7. Scarborough, ON M1R 5G1 Tel: (416) 899-1882 Fax: (905) 882-8812 www.sentec.ca -----Original Message----- From: Genny Date: Tue, 1 Jun 2010 09:23:41 To: <[log in to unmask]> Subject: Re: [TN] Crystalline solder balls Thanks for yours and Vladimir's comments. These are SAC balls. We don't have any SEM available. These are the best magnification we can come up with right now. We have better microscope images that we can see, but the camera is not on the best microscope. -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman Sent: May 28, 2010 12:24 PM To: [log in to unmask] Subject: Re: [TN] Crystalline solder balls Hi Genny - yes, these structures have been reported in the industry before so you are in luck. If these were tin/lead solderballs, you most likely are looking at copper/tin intermetallic needles structures and if these are SAC305 solderballs, you are most likely looking at silver/nickel intermetallic needles. These structures are an indication that the original reflow solder profile or the rework profile was temperature/time excessive. Once the intermetallic phases form, they have melting points much higher than the surrounding solder so when you removed the BGA component, they become more visible as the solder joint volume is removed. A second root cause would be incorrect metallurgical composition issues. Nice photo - the first one is going into my photo gallery. Do you have any higher magnification shots? Dave Hillman Rockwell Collins [log in to unmask] Genny Sent by: TechNet <[log in to unmask]> 05/28/2010 12:52 PM Please respond to TechNet E-Mail Forum <[log in to unmask]>; To [log in to unmask] cc Subject [TN] Crystalline solder balls http://ipc-technet.groupsite.com/gallery/13595 May not get many responses on a Friday before a long weekend, but your ideas on what I am seeing is appreciated. Sorry the camera on our microscope is not great. This is some of what remains on a board after a BGA is removed with a Summit hot air rework station. > Genny ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 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 -----------------------------------------------------