From what I've read, the problem doesn't look like black pad since the balls were originally stuck to the device. Black pad would cause no wetting or improper soldering. The pics show tiny areas distributed evenly across the contact surface where complete alloying (i.e. solder jointing) has taken place, but the largest proportion of the area is intermetallic compound where the fracture has occurred. Strangely, most proper alloying, usually seems to take place around the perimeter of the join, but I don't see that here. Don't understand the phenomenon, so can't offer scientific explanation, but I offer is as a snippet of info for your consideration. Earl's problem looks very similar to one that our old friend Ingemar had at Eriksson a while back. He produced a large paper on the investigation they carried out - not 100% tidy, but very interesting reading indeed. One of his conclusions was that the Nickel plating bath was maybe too high in phosphor, causing weak or brittle Nickel layer. Another was Nickel passivation, [possibly caused by the substrate drying out between plating processes, or, as has been suggested, by too-thin a gold layer]. Given the commercial concerns of component manufacturers to offer product at the cheapest prices, it could be that they are extending the life of their plating baths too far in an attempt to keeps costs down. Earl, maybe you ought to see how frequently TI and others change their baths, or conversely, what they hold the phosphor content to. A recommendation I was handed was that P. content shouldn't exceed about 8%, though I've heard of 10% being acceptable. You have my heart-felt sympathy with your bains (and yes it is a proper term, as in 'bain of your life'). Peter "Furrow, Robert Gordon To: [log in to unmask] (Bob)" cc: (bcc: DUNCAN Peter/Asst Prin Engr/ST <furrow@LUCEN Aero/ST Group) T.COM> Subject: Re: [TN] Earls pics are up, and a Sent by: question... TechNet <[log in to unmask] ORG> 03/13/02 10:01 PM Please respond to "TechNet E-Mail Forum."; Please respond to "Furrow, Robert Gordon (Bob)" Earl, As others have stated, the 10X picture looks like there was never intended to be a ball there. Maybe it is the lower mag and a trick of the lighting that makes it look that way. Anyway, on the other pics it looks a lot like a clean fracture right at the intermetallic layer. Is the underlying metal nickel? Was the BGA fabricator using ENIG as a solderability coating prior to the attachment of the balls? Could this be another case of "black pad"? I know we have had instances where this has been the case. Very low level identified, but who knows how many times the actual cause is overlooked. As with the ENIG issue on PWB surfaces, some suppliers may be able to completely eliminate the problem, others may have it at a low level, and the unfortunate few may be plagued with this problem. Just some questions you might want to check in to. Thanks, Robert Furrow Printed Wiring Board Engineer Supply Chain Networks Lucent Technologies 978-960-3224 [log in to unmask] -----Original Message----- From: Earl Moon [mailto:[log in to unmask]] Sent: Wednesday, March 13, 2002 8:31 AM To: [log in to unmask] Subject: Re: [TN] Earls pics are up, and a question... Jim, BGA's used to be my best friend, except for Arleen Weinberger and other ladies of extreme beauty and brains. Now they are a bain, if tha's a proper term. It's like the whole BGA world has gone to hell. Even board suppliers are starting to suck who once had my total faith and confidence based on constant evaluation, re-evaluation, and qualification. At least now I have a compadre in this mess. Thanks for sharing the gief but I'm honestly stumped but for an undying dedication to gettin this damn thing resolved. The TI thing was bad enough but now another major supplier adds to the MESS. Did you give us your paper and/or its location? I'm reading all I can, OVER AND OVER AGAIN, notwithstanding posting my brains and guts out on this site. Hell, even Sir Werner and his cohorts can't do much. It has to be up to the suppliers to come forth. Thought I was working concurrently with TI. Now I'm not sure again, and haven't even begun talking with the other major supplier with whom my last pics are associated. Your statement about "Every time there was a component failure, it was attributed to an open BGA solder joint" sure used to ring true but was resolved, for a time. It seems now to be coming back. Sorry about your, hopefully healed black eye, but should not have been the case. However, some should suffer such a fate based on your thoughts about how the missing ball attachment area looked compared to mine. This solder "remnant" crap is exactly my problem and others soon to experience it. All other surface conditions point to some process management inadequacies and someone knows what they are and what are the failure modes/mechanisms. Just looks like unsolderable surfaces to me and whatever happened to the IMC layer whether too thick, too thin, or just plane way to oxidized. My progress is limited to a very small company resource capability. The company has spent way too much time and money doing minimal analysis. Who the hell could afford to do more anyway. Like Sir Werner says, this crap is just being thrown over the fence for all us ROOKIES to suck through a garden hose. I don't do that. I believe you're right about the nickel gold thing. What else could it be. TI even admitted one of its suppliers was replaced to do a better job. That hasn't been proven yet either. Maybe Friday it will when we get our first assemblies. We'll ge to the bottom, and I do mean bottom, of this soon but maybe not soon enough for some. Thanks JM for some outstanding insights. Finally feels a bit, though sadly, comforting having someone else having gone through this. Earl ---------------------------------------------------------------------------- ----- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------- ----- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 --------------------------------------------------------------------------------- [This e-mail is confidential and may also be privileged. If you are not the intended recipient, please delete it and notify us immediately; you should not copy or use it for any purpose, nor disclose its contents to any other person. Thank you.] --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d 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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site http://www.ipc.org/html/forum.htm for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------