Werner, I’ve tried to describe it better Fan-out clocking correlation: The fractures/poor wetting appear to start at the trace to land junction, rather than what one might expect from t-cycling fatigue, or ict strain. In the pictures I posted, I tried to show the damage clocking 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 component warpage. 'What points to 'Black Pad' is the periphery location—during soldering the periphery gets a lot more heat than the interior, thus more Ni goes into solution with Sn, thus leaving a higher P-concentration at periphery pads, thus they are weaker, thus component warping causes interfacial separation on the periphery & 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]> [mailto:[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]<mailto:[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]<mailto:[log in to unmask]> Chris Mahanna <[log in to unmask]<mailto:[log in to unmask]>> Sent by: TechNet <[log in to unmask]<mailto:[log in to unmask]>> 10/11/2010 11:29 AM Please respond to TechNet E-Mail Forum <[log in to unmask]<mailto:[log in to unmask]>>; Please respond to Chris Mahanna <[log in to unmask]<mailto:[log in to unmask]>> To [log in to unmask]<mailto:[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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