The BGA device side may have low area of contact due to geometry, and large grain size (reflowed more than once = ball formation and assembly attach). Plus excessive substrate gold or immersion gold black pad may result either intermetallic formation (brittle) or poor interface (weak). My 2cents: (1) get a good vendor for the substrate (no black pad). (2) and/or use thin good quality gold (flash gold) (3) license Motorola patent (can't remember the number) to form a dam around the interface using thick solder mask, to force the fracture side at middle (fattest ball diameter area).... If you got easy fracture BGA (cheap, no qual, no licensing, etc)... do not use on wireless gadgets, like cell phone. it get drop a lot...(some blame goes to the design, slippy design, really. another story) jk -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Victor G. Hernandez Sent: Monday, June 13, 2005 3:16 PM To: [log in to unmask] Subject: Re: [TN] BGA Intermittent Saga, part 2 You state to look for Au cyanide etching in the eless Ni. With what instrument or is this under a high power micro scope (1000X). Can you describe what to look for or perhaps you can share a photo of the artifact you are suggesting. Victor, -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Leo Higgins Sent: Monday, June 13, 2005 1:39 PM To: [log in to unmask] Subject: Re: [TN] BGA Intermittent Saga, part 2 Excessive stress from pneumatic presses used to bond heat sinks to BGAs after board level assembly has been shown to induce failure at the solder to BGA pad on packages that meet pre-SMT assembly quality specs in all ways. Subsequent analyses may show no evidence of black pad (cross sectioning to look for Au cyanide etching into the eless Ni, etc.). Best regards, Leo Director of Applications Engineering ASAT, Inc. 3755 Capital of Texas Highway, Suite 100 Austin, Texas 78704 ph 512-383-4593 fx 512-383-1590 [log in to unmask] www.asat.com The information contained in this electronic message is CUSTOMER/SUPPLIER PRIVILEGED AND CONFIDENTIAL INFORMATION intended only for the use of the individual or entity named above. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution and copying of this communication is strictly prohibited. If you have received this communication in error, please immediately notify the sender by electronic mail. Thank you. -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Jana Carraway Sent: Monday, June 13, 2005 1:01 PM To: [log in to unmask] Subject: Re: [TN] BGA Intermittent Saga, part 2 Werner, If it's black pad on the component side, how would Kerry prove or disprove it? Could he find the cause by using Auger or cross-section? What would be the appropriate tests to perform to find root cause? Should he send a component back to the supplier for root cause analysis? Thank you, Jana Carraway Jana Carraway MSEI - Advanced Technology Group 6024 S.W. Jean Road Lake Oswego, OR 97035 503.697.5291, ext 1180 email: [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Werner Engelmaier Sent: Monday, June 13, 2005 10:04 AM To: [log in to unmask] Subject: Re: [TN] BGA Intermittent Saga, part 2 Hi Kerry, You most likely have 'Black Pad' on the componet side. That, together with the stess concentration from the SMD-geometry, caused a briitle ionterfacial overstress failure. 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 ----------------------------------------------------- --------------------------------------------------- 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 ----------------------------------------------------- --------------------------------------------------- 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 -----------------------------------------------------