I'm just wondering when we stop blaming "Black Pad" all the time? It well may be that the UBM on the Kerry's package wasn't electroless but electrolytic Ni, and he could see an example of "Brittle Fracture" type of phenomenon (it doesn't happen only on ENIG finished boards). Let see what the package supplier comes up with.
Regards,
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 Werner Engelmaier
Sent: Monday, June 13, 2005 1:04 PM
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
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