Cu6Sn5 crystal growth mechanisms during solidification of electronic interconnections

J. W. Xian, S. A. Belyakov, M. Ollivier, K. Nogita, H. Yasuda, C. M. Gourlay

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)

Abstract

The growth mechanisms of primary Cu6Sn5 are studied in Sn-Cu alloys and solder joints by combining EBSD, FIB-tomography and synchrotron radiography. With increasing cooling rate and Cu content, Cu6Sn5 crystals developed from faceted hexagonal rods to grooved rods, in-plane branched faceted crystals and, finally, to nonfaceted dendrites. This range of growth morphologies has been rationalised into a kinetic microstructure map. Cu6Sn5 hexagonal rods grew along [0001] bounded by {101¯0} facets and Cu6Sn5 dendrites branched along <405> in the {101¯0} planes. The faceted to nonfaceted transition indicates a kinetic interface roughening transition and a gradual change in mechanism from lateral growth governed by anisotropic attachment kinetics to continuous growth governed by diffusion and curvature. Finally, it is shown that the full range of Cu6Sn5 morphologies that grew for different composition and cooling rate combinations in bulk alloys can be engineered to grow in solder joints made with a single composition (Sn-0.7 wt%Cu/Cu) by altering the peak temperature and the cooling rate.

Original languageEnglish
Pages (from-to)540-551
Number of pages12
JournalActa Materialia
Volume126
DOIs
Publication statusPublished - Mar 1 2017

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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