Been there, did this, done that and everything you say is correct. The current IPC-7095A does not deal in depth with the as-received BGA package prior to processing. Garbage in, Garbage out still applies. Dewey -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of John Perry Sent: Monday, October 18, 2004 12:32 PM To: [log in to unmask] Subject: [TN] BGA ball-to-package failures TechNet Posting on Behalf of Tom Clifford, Lockheed Martin, Sunnyvale CA: I'm concerned about incoming BGA ball-to-package integrity. All our solder-joint-cycle reliability predictions deal with cyclic-fatigue shear failure thru the solder-joint fillet, top and/or bottom. And, most t-cycle failures do occur thru the fillet, as anticipated. However, we have seen, dramatically, that BGA balls can pop right off the interface at the bottom of the BGA package, in "premature" failure. Certainly this sort of failure cannot be predicted on fundamental grounds, or even predicted based on actual test, or compensated for in our component/PWB selection/design/processing. If the BGA ball is "weak" at the ball-package interface, all prediction bets are off!!! We are at the mercy of the supplier and of that particular part...P/N/...lot...batch. Additionally, the exposure will get worse, in the hi-rel mil-aero world, as BGA applications increase in number and consequence, and as supply-chains expand. I'm thinking the industry (users and supplier/packagers) should do at least these things: 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. 2)Start gathering a data base, linking mean and variability to material and process. 3)Start relating this relative ball-to-package strength data to maverick failures at the interface, in t-cycle testing. 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. Certainly the causes and consequences and fixes will be and probably are being addressed, but industry recognition of the problem, up-front would be useful. Perhaps the "problem" has already been solved, but my guess is that it needs some attention, to help move it way down the list of reliability concerns. Comments? Tom Clifford Mike Green Production Design Engineering Dept 7JGS; B157; Col 3D3 Lockheed Martin Space Systems 1111 Lockheed Martin Way Sunnyvale, CA 94089 office 408-743-1635 Synergy works at LMC. "Show me the data." --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------