Microstructure and mechanical behavior of novel rare earth-containing Pb-free solders

M. A. Dudek, R. S. Sidhu, Nikhilesh Chawla, M. Renavikar

Research output: Contribution to journalArticlepeer-review

71 Scopus citations


Sn-rich solders have been shown to have superior mechanical properties when compared to the Pb-Sn system. Much work remains to be done in developing these materials for electronic packaging. In this paper, we report on the micro-structure and mechanical properties of La-containing Sn-3.9Ag-0.7Cu alloys. The addition of small amounts of La (up to 0.5 wt.%) to Sn-Ag-Cu refined the microstructure by decreasing the length and spacing of the Sn dendrites and decreased the thickness of the Cu 6Sn 5 intermetallic layer at the Cu/solder interface. As a result of the change in the microstructure, Sn-Ag-Cu alloys with La additions exhibited a small decrease in ultimate shear strength but significantly higher elongations compared with Sn-Ag-Cu. The influence of LaSn 3 intermetallics on microstructural refinement and damage evolution in these novel solders is discussed. Our results have profound implications for improving the mechanical shock resistance of Pb-free solders.

Original languageEnglish (US)
Pages (from-to)2088-2097
Number of pages10
JournalJournal of Electronic Materials
Issue number12
StatePublished - Dec 2006


  • Ductility
  • Pb-free solder
  • Rare-earth

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry


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