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In situ imaging of microstructure formation in electronic interconnections

Salleh MA 1 , Gourlay CM 2 , Xian JW 2 , Belyakov SA 2 , Yasuda H 3 , McDonald SD 1 Show all authors , Nogita K 1

Affiliations 

  • 1 Nihon Superior Centre for the Manufacture of Electronic Materials (NS CMEM), School of Mechanical and Mining Engineering, The University of Queensland, 4072 St Lucia, Queensland, Australia
  • 2 Department of Materials, Imperial College, London SW7 2AZ, United Kingdom
  • 3 Department of Materials Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
Sci Rep, 2017 Jan 12;7:40010.
PMID: 28079120 DOI: 10.1038/srep40010

Abstract

The development of microstructure during melting, reactive wetting and solidification of solder pastes on Cu-plated printed circuit boards has been studied by synchrotron radiography. Using Sn-3.0Ag-0.5Cu/Cu and Sn-0.7Cu/Cu as examples, we show that the interfacial Cu6Sn5 layer is present within 0.05 s of wetting, and explore the kinetics of flux void formation at the interface between the liquid and the Cu6Sn5 layer. Quantification of the nucleation locations and anisotropic growth kinetics of primary Cu6Sn5 crystals reveals a competition between the nucleation of Cu6Sn5 in the liquid versus growth of Cu6Sn5 from the existing Cu6Sn5 layer. Direct imaging confirms that the β-Sn nucleates at/near the Cu6Sn5 layer in Sn-3.0Ag-0.5Cu/Cu joints.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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