It is well established that Pb free alloys tend to solder less readily than Sn/Pb. It is not clear that this is always a major problem, but two factors combine to make it more of a concern for flip chip than for other applications. Not surprisingly, wetting and spreading appears to become less effective as the solder volume is reduced and a larger fraction of it is near the surface. At the same time assembly yields tend to become more sensitive to this. The present paper addresses the assembly of flip chips with Sn/Ag/Cu bumps onto Ni/Au and OSP coated copper pads on organic substrates. Soldering defects observed included incomplete wetting and collapse, as well as poor self centering. The sensitivity to fluxes, reflow profiles, and substrate pads were investigated and potential consequences for assembly yields calculated numerically.
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ASME 2002 International Mechanical Engineering Congress and Exposition
November 17–22, 2002
New Orleans, Louisiana, USA
Conference Sponsors:
- Electronic and Photonic Packaging Division
ISBN:
0-7918-3648-7
PROCEEDINGS PAPER
Lead-Free Flip Chip Assembly Available to Purchase
Sunil Gopakumar,
Sunil Gopakumar
State University of New York at Binghamton, Binghamton, NY
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Vinodh Poyyapakkam,
Vinodh Poyyapakkam
State University of New York at Binghamton, Binghamton, NY
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Dan Blass,
Dan Blass
Universal Instruments Corporation, Binghamton, NY
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Peter Borgesen,
Peter Borgesen
Universal Instruments Corporation, Binghamton, NY
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K. Srihari
K. Srihari
State University of New York at Binghamton, Binghamton, NY
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Sunil Gopakumar
State University of New York at Binghamton, Binghamton, NY
Vinodh Poyyapakkam
State University of New York at Binghamton, Binghamton, NY
Dan Blass
Universal Instruments Corporation, Binghamton, NY
Peter Borgesen
Universal Instruments Corporation, Binghamton, NY
K. Srihari
State University of New York at Binghamton, Binghamton, NY
Paper No:
IMECE2002-39251, pp. 105-109; 5 pages
Published Online:
June 3, 2008
Citation
Gopakumar, S, Poyyapakkam, V, Blass, D, Borgesen, P, & Srihari, K. "Lead-Free Flip Chip Assembly." Proceedings of the ASME 2002 International Mechanical Engineering Congress and Exposition. Electronic and Photonic Packaging, Electrical Systems Design and Photonics, and Nanotechnology. New Orleans, Louisiana, USA. November 17–22, 2002. pp. 105-109. ASME. https://doi.org/10.1115/IMECE2002-39251
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