Electrochemical deposition and structural characterization of Au-Sn alloys

Antonello Vicenzo, Michela Rea, Luca Vonella, Massimiliano Bestetti, Pietro Luigi Cavallotti

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


In the present work the electrochemical deposition of Au-Sn alloys is addressed and a cyanide-free process is presented. The electrolyte is an acidic thiourea solution containing gold as a Au[CS(NH2)2] + complex and tin as stannous ions. Results concerning the plating process development and deposit characterization are reported. Au-Sn alloy films with a Sn content up to 50 at% and a single-phase structure can be obtained from the acidic thiourea-Au(I) solution under pulsed current plating conditions. Alloy deposits show three main crystal structures: a face centred cubic (fcc) Au(Sn) solid solution, extending up to 7 at% Sn; a hexagonal close-packed structure, of the same type as the metallurgical ζ phase, up to about 18 at% Sn; and a NiAs-type structure, corresponding to the δ phase of the equilibrium diagram, with an enlarged homogeneity range. Mechanical properties of thin layers of Au-Sn alloys derived from micro-indentation measurements follow the structural modification with the alloy composition. The ordered intermetallic phases occurring in the equilibrium binary system, in particular the β and ζ′ phases at 8 at% and 16 at% Sn, respectively, are not detected in the electrodeposited alloys. The main factors controlling electrochemical phase formation are pointed out, considering the differences between the phase structure of the electrodeposited alloys and the equilibrium phase diagram.

Original languageEnglish
Pages (from-to)159-166
Number of pages8
JournalJournal of Solid State Electrochemistry
Issue number3
Publication statusPublished - Feb 2004
Externally publishedYes


  • Au-Sn electrodeposition
  • Electrodeposits structure
  • Thiourea
  • White gold

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Electrochemistry

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