Hi Chris, That may still be 'Black Pad'—remember the PCB is much hotter than the BGA and the solder joints are reflowed by conductive heating through the PCB. It stands to reason, that the traces are even hotter than just the resin surface ;thus, causing more Ni going into Sn-solution right there. Werner -----Original Message----- From: Chris Mahanna <[log in to unmask]> To: Werner Engelmaier <[log in to unmask]>; [log in to unmask] <[log in to unmask]> Sent: Mon, Oct 11, 2010 4:36 pm Subject: RE: [TN] Mech. damage or poor wetting? Werner, I’ve tried to describe it better Fan-out clocking correlation: The fractures/poor wetting appearto start at the trace to land junction, rather than what one might expect from t-cyclingfatigue, or ict strain. In the pictures I posted, I tried to show the damageclocking around with the traces. I thought that I had heard or read somewhere that this is common,but you guys are a lot faster than a literature search. Chris From: Werner Engelmaier[mailto:[log in to unmask]] Sent: Monday, October 11, 2010 4:10 PM To: [log in to unmask]; Chris Mahanna Subject: Re: [TN] Mech. damage or poor wetting? Hi Chris, What do you mean by 'fanout clocking?' I think you have a combination of 'Black Pad' and componentwarpage. 'What points to 'Black Pad' is the periphery location—during soldering theperiphery gets a lot more heat than the interior, thus more Ni goes intosolution with Sn, thus leaving a higher P-concentration at periphery pads, thusthey are weaker, thus component warping causes interfacial separation on theperiphery & pad cratering where the P-concentration is lower. Werner -----Original Message----- From: Chris Mahanna <[log in to unmask]> To: [log in to unmask] Sent: Mon, Oct 11, 2010 2:40 pm Subject: Re: [TN] Mech. damage or poor wetting? Here are a few pictures http://ipc-technet.groupsite.com/gallery/16011 this job is a mixed bag. Currently we suspect soldering, cratering, ICT and t-cycling damage Chris From: [log in to unmask] [mailto:[log in to unmask]] Sent: Monday, October 11, 2010 2:22 PM To: TechNet E-Mail Forum; Chris Mahanna Cc: [log in to unmask] Subject: Re: [TN] Mech. damage or poor wetting? Hi Chris - do you have any pictures you can share? Dave Hillman Rockwell Collins [log in to unmask] Chris Mahanna <[log in to unmask]> Sent by: TechNet <[log in to unmask]> 10/11/2010 11:29 AM Please respond to TechNet E-Mail Forum <[log in to unmask]>; Please respond to Chris Mahanna <[log in to unmask]> To [log in to unmask] cc Subject [TN] Mech. damage or poor wetting? We have a BGA dye-n-pry job that shows board side sj damage with a strong correlation to fan-out clocking. We also have some microsection evidence of poor wetting. All damage/dye is on perimeters. Is this an indication of heat sinking and subpar wetting, or can it be completely mechanical? Both? Thanks Chris ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. 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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 ----------------------------------------------------- ______________________________________________________________________ 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 -----------------------------------------------------