RELIABILITY ASSESSMENT OF REBALLED BGAsAuthors: J. Li, et al.
Company: Watson Institute for Systems Excellence at the State University of New York and Sanmina-SCI Corporation
Date Published: 10/4/2009 Conference: SMTA International
In this study, SAC305 solder bumps from lead-free components were replaced with SnPb solder bumps. A series of tests and inspections were carried out to evaluate the reliability of these reballed components. After the reballing operation, the solder bump sizes were measured and they exhibited ‘good’ dimensional consistency. Voiding, which has been reported as a concern in the case of reballed components, was assessed via X-ray inspection and was determined to be a non-issue. Ball shear testing, which was used as a solder joint-level mechanical test to evaluate the strength of the re-balled solder joints, indicated adequate solder joint strength. Solder joint microstructure was studied via metallographic techniques. It was found that the thickness of the interfacial Intermetallic Compound (or IMC) was in the acceptable range. In addition, after assembly of the reballed BGA components, the packages were subjected to Environmental Stress Screening (ESS) tests, followed by in-circuit and functional tests. No failures were detected. It was therefore inferred that the re-balled components exhibited adequate performance without any degradation and can serve as a solution for such a ‘mixed’ system.
Key words: Printed Circuit Board Assembly, BGA Components, Re-balling, Reliability, Mixed Alloy Assembly
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