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The microstructure of Sn in near-eutectic Sn–Ag–Cu alloy solder joints and its role in thermomechanical fatigue

Published online by Cambridge University Press:  03 March 2011

Donald W. Henderson*
Affiliation:
IBM Corporation, Endicott, New York 13760
James J. Woods
Affiliation:
IBM Corporation, Endicott, New York 13760
Timothy A. Gosselin
Affiliation:
IBM Corporation, Endicott, New York 13760
Jay Bartelo
Affiliation:
IBM Corporation, Endicott, New York 13760
David E. King
Affiliation:
Endicott Interconnect Technologies, Endicott, New York 13760
T.M. Korhonen*
Affiliation:
Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853
M.A. Korhonen
Affiliation:
Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853
L.P. Lehman
Affiliation:
Physics Department, Materials Science Program, Binghamton University,Binghamton, New York 13902
E.J. Cotts
Affiliation:
Physics Department, Materials Science Program, Binghamton University,Binghamton, New York 13902
Sung K. Kang
Affiliation:
IBM Corporation, T.J. Watson Research Center, Yorktown Heights, New York 10598
Paul Lauro
Affiliation:
IBM Corporation, T.J. Watson Research Center, Yorktown Heights, New York 10598
Da-Yuan Shih
Affiliation:
IBM Corporation, T.J. Watson Research Center, Yorktown Heights, New York 10598
Charles Goldsmith
Affiliation:
IBM Corporation, Hopewell Junction, New York 12533
Karl J. Puttlitz
Affiliation:
IBM Corporation, Hopewell Junction, New York 12533
*
a) Address all correspondence to these authors. e-mail: donwhend@us.ibm.com, tkk3@cornell.edu, lplehman@binghamton.edu
a) Address all correspondence to these authors. e-mail: donwhend@us.ibm.com, tkk3@cornell.edu, lplehman@binghamton.edu
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Abstract

During the solidification of solder joints composed of near-eutectic Sn–Ag–Cu alloys, the Sn phase grows rapidly with a dendritic growth morphology, characterized by copious branching. Notwithstanding the complicated Sn growth topology, the Sn phase demonstrates single crystallographic orientations over large regions. Typical solder ball grid array joints, 900 μm in diameter, are composed of 1 to perhaps 12 different Sn crystallographic domains (Sn grains). When such solder joints are submitted to cyclic thermomechanical strains, the solder joint fatigue process is characterized by the recrystallization of the Sn phase in the higher deformation regions with the production of a much smaller grain size. Grain boundary sliding and diffusion in these recrystallized regions then leads to extensive grain boundary damage and results in fatigue crack initiation and growth along the recrystallized Sn grain boundaries.

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Articles
Copyright
Copyright © Materials Research Society 2004

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References

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