John, we have seen this a number of times,and I've been looking at some of these cases.You can start with some brief examinations: 1. are there any solder remnants on the board pads. If so, how does it look like? Randomly spread or ring formed along the pad's circumperifery? 2.apply a solder etchant that does not etch Nickel to get an opinion about the solder wetting 3. apply a nickel etchant that does not etch solder to get an opinion about the nickel covering, skip plating, IMC s 4. dispens a 50-100 micrometer solder paste on the failing board pads and run through your oven.Wetting, dewetting or non-wetting. You need a experienced person to do the tests and to interprete the results. In right hands, often better than pages and pages of EDAX analysis. Inge ---- Original Message ----- From: "John Parsons" <[log in to unmask]> To: <[log in to unmask]> Sent: Friday, November 19, 2010 9:31 PM Subject: [TN] BGA Falling off PCA >I am not seeing a lot of the usual Friday quiz traffic so I know you > guys-n-gals are just itching for some real work :o). > > > > We are a PCB fabricator and one of our customers has returned some > assemblies to us for feedback. What they noticed when someone > accidentally > dropped an assembly is that the BGA (352 pin Cirrus Logic EP9312-CBZ) > popped > off the board. They then proceeded to drop a few more from a height of > about a foot with the same results. All the other components on this > Pb-free assembly stay fast. > > > > We have received three PCA's and 5 BGA's. On one of the BGA's a single > ball > has remained on the PCB. The rest of them all the balls have broken > cleanly > from the PCB leaving a very flat (under x10 magnification) dull gray > surface. I sure wish that I could take photo's but lighting is critical > and > I don't think that I have the resources to get photo's that would do > justice > to what the naked eye is seeing. > > > > Also of note is that the BGA lands are mask defined with a 31mil circuit > pad > and 26mil solder mask relief. > > > > Does anyone have any ideas as to how we can determine the root cause of > this > failure. This part has been built for some time but previously the > surface > finish on the PCB was a solder finish. This is the first run of the > boards > that has an ENIG finish. This doesn't look to me like a raw board issue > but > that is where everyone looks first isn't it ;o). > > > > Regards > > > > John Parsons > > > > > > ______________________________________________________________________ > 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 > ----------------------------------------------------- ______________________________________________________________________ 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 -----------------------------------------------------