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Title: Advances in Pb-free solder microstructure control and interconnect design

New electronics applications demanding enhanced performance and higher operating temperatures have led to continued research in the field of Pb-free solder designs and interconnect solutions. In this paper, recent advances in the microstructural design of Pb-free solders and interconnect systems were discussed by highlighting two topics: increasing β-Sn nucleation in Sn-based solders, and isothermally solidified interconnects using transient liquid phases. Issues in β-Sn nucleation in Sn-based solders were summarized in the context of Swenson’s 2007 review of the topic. Recent advancements in the areas of alloy composition manipulation, nucleating heterogeneities, and rapid solidification were discussed, and a proposal based on a multi-faceted solidification approach involving the promotion of constitutional undercooling and nucleating heterogeneities was outlined for future research. The second half of the paper analyzed two different approaches to liquid phase diffusion bonding as a replacement for high-Pb solders, one based on the application of the pseudo-binary Cu-Ni-Sn ternary system, and the other on a proposed thermodynamic framework for identifying potential ternary alloys for liquid phase diffusion bonding. Furthermore, all of the concepts reviewed relied upon the fundamentals of thermodynamics, kinetics, and solidification, to which Jack Smith substantially contributed during his scientific career.
 [1] ;  [1] ;  [2] ;  [2] ;  [1]
  1. Purdue Univ., West Lafayette, IN (United States)
  2. Ames Lab. and Iowa State Univ., Ames, IA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 1547-7037; PII: 476
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Journal of Phase Equilibria and Diffusion
Additional Journal Information:
Journal Volume: 37; Journal Issue: 4; Journal ID: ISSN 1547-7037
ASM International
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
Country of Publication:
United States
36 MATERIALS SCIENCE; constitutional undercooling; grain nucleation; liquid phase diffusion bonding; Pb-free solder; ternary diagrams; transient liquid
OSTI Identifier: