(1) 45 degree inclined crack with grain boundary sliding - some kindly of cyclic stress due to possibly thermal expansion difference between the module and board. (either a large chip, or multi-chip stack on module side... compare to the board of cte of 17ppm or so for example). The module must be very rigid or very flexable... - look like rigid would be apply... just a guess. (2) significant ppt of high melting phase prior to eutectic formation, the solder ball material look like is off eutectic Pb/Sn with reballing cooling at low rate. - weak structually speaking. (3) the operating temperature and environment may got something to do with it. - no info provided based on the email below. just a guess. jk On Aug 6, 2014, at 2:48 PM, Chris Mahanna wrote: > We see hundreds of cracked solder joints every year, but I can't > say that I've ever seen one quite like this. I have some > suspicions, but I'll keep them to myself, as to not prejudice the > crowd. > EDS maps are forthcoming. > > This is a caught in-the-wild field failure of a 48-pin BGA > Reballed to SnPb > ENIG on board side > Ni barrier on component side > > http://stevezeva.homestead.com/45268-1.JPG > > http://stevezeva.homestead.com/45268-2.JPG > > http://stevezeva.homestead.com/45268-8.JPG > > Thoughts? And Thanks to Steve! > > > Chris Mahanna > President, Technical Manager > Robisan Laboratory Inc. > > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud > service. > For more information please contact helpdesk at x2960 or > [log in to unmask] > ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________