Size control and characterization of Sn-Ag-Cu lead-free nanosolders by a chemical reduction process

Kam Chuen Yung, C. M.T. Law, C. P. Lee, B. Cheung, Tai Man Yue

Research output: Journal article publicationJournal articleAcademic researchpeer-review

23 Citations (Scopus)


Sn-3.0Ag-0.5Cu nanosolders were synthesized via a chemical reduction method. Polyvinyl pyrrolidone (PVP) and sodium borohydride (NaBH4) were employed as surfactant and reducing agent, respectively. Ultraviolet-visible (UV-visible) absorption and x-ray diffraction patterns revealed that alloying had successfully taken place during the reduction process. Different amounts of PVP and NaBH4additions influenced the nanosolder particle size. Under varying reaction temperatures and pH values, various ranges of nanosolder size were obtained. Optimized nanosolders were studied by differential scanning calorimetry to investigate the depression of the melting temperature, and were analyzed by transmission electron microscopy to measure actual particle sizes. The dependence of the particle size on the melting temperature was observed. The melting point was depressed to 204.4°C when the average diameter of the nanosolders was 20 nm. Although SnO2was formed on the nanosolders, it could be cleaned by citric acid. These low-melting-temperature Sn-Ag-Cu nanosolders are candidates for use in lead-free interconnect applications.
Original languageEnglish
Pages (from-to)313-321
Number of pages9
JournalJournal of Electronic Materials
Issue number2
Publication statusPublished - 1 Feb 2012


  • chemical reduction
  • Lead-free
  • melting temperature
  • nanosolders
  • Sn-3.0Ag-0.5Cu

ASJC Scopus subject areas

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


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