Hi Tom, As you recognized, this is bad quality, and thus not subject to any modeling or prediction capability. 1)Develop or identify some sort of standard physical test (shear or tensile) to measure the as-shipped or as-received strength of the ball-to-package joint, probably room temperature, maybe at an elevated temperature. We are way ahead of you on this; take alook at: IPC/JEDEC-9702 “Monotonic Bend Test Method for Surface Mount Solder Attachments” and upcoming IPC-9703 “Shock Test Methods and Qualification Requirements for Surface Mount Solder Attachments;” these standards address the issues of "brittle" failure and waek metallizations. IPC-9701 “Performance Test Methods and Qualification Requirements for Surface Mount Solder Attachments” deals with the reliability expectations of good solder joints on the various components. 2)Start gathering a data base, linking mean and variability to material and process. Unfortunately, that may not be particularly helpful, since these kind of 'defective' attachment metallizations are 'defective' on a sporadic basis without much in terms of 'predictors,' and when they occur they are typically catastrophic. 3)Start relating this relative ball-to-package strength data to maverick failures at the interface, in t-cycle testing. See 2) 4)Depending on results, and if these failures persist in mil/aero applications, consider adding a suitable qualification and lot-acceptance test and criteria to incoming BGAs. See 1) Regards, Werner Engelmaier Engelmaier Associates, L.C. Electronic Packaging, Interconnection and Reliability Consulting 7 Jasmine Run Ormond Beach, FL 32174 USA Phone: 386-437-8747, Fax: 386-437-8737, Cell: 386-316-5904 E-mail: [log in to unmask], Website: www.engelmaier.com --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 -----------------------------------------------------