Right, it does sound weird and on top of it, the Ni layer doesn't look that bad (cavitation wise I mean). What I think might have happen is that the platter had a problem with ENIG (gold layer to be exact) and decided to strip off Au and plate with Sn. As far as I know, they do it. Vladimir Vladimir Igoshev, Ph. D. Senior Materials Researcher Research in Motion 451 Phillip St. Waterloo, ON, N2L 3X2 Voice: (+1) 519-888-7465, ext. 5283 Fax: (+1) 519-886-0863 E-mail: [log in to unmask] -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Ingemar Hernefjord (KC/EMW) Sent: Wednesday, June 22, 2005 10:02 AM To: [log in to unmask] Subject: Re: [TN] BGA Intermittent Saga, part 2 Nickel corrosion? Under tin plating? I don't understand. I would rather suggest tin plating over bad wetting. In all metalurgical handbooks, nickel has the grade 'poor' , when talking solder wetting. I've had several incidents with bad tin plating on nickel the last year. E.g. a multipin plastic package, on which we could shear off the tin by pulling the component legs between your thumb and index finger nails!! If it's really nickel corrosion, what caused that? This is not a ENIG nickel corrosion situation. Is it possible to get a SEM cross section image? Good Luck Ingemar Hernefjord Ericsson Microwave Systems -----Original Message----- From: TechNet [mailto:[log in to unmask]]On Behalf Of Leo Higgins Sent: den 22 juni 2005 06:18 To: [log in to unmask] Subject: Re: [TN] BGA Intermittent Saga, part 2 I will send a pair of pictures from an Amkor paper showing optical micrographs showing Ni corrosion and a pad with no Ni corrosion to Steve to see if he can put up on his web site. Published studies on Black Pad issues often show similar structures. Steve can you post the 2 photos? I will send after this note. 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: [log in to unmask] [mailto:[log in to unmask]] Sent: Monday, June 13, 2005 2:16 PM To: [log in to unmask]; [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. 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