Electrodeposition of Sn-Ag alloys and evaluation of connection reliability for automotive connectors

Hiroaki Nakano, Satoshi Oue, Masaaki Uranaka, Masataka Masuda, Hisaaki Fukushima, Yoshifumi Saka, Shigeru Sawada, Yasuhiro Hattori

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    11 Citations (Scopus)


    Electrodeposition behavior of Sn-Ag alloys was investigated at current density 1-1000 A·m-2 in both sulfate and pyrophosphate-iodide solutions at 298 K, and the contact resistance of Sn-Ag alloys deposited on a Cu connector was evaluated. In both solutions, Ag behaved as a more noble metal than Sn, showing regular codeposition. The difference in deposition potential between Ag and Sn was 0.4 V in the pyrophosphate-iodide solution and 0.2 V in a sulfate solution containing thiourea as a complexing agent for Ag+ ions. The deposits obtained from a pyrophosphate-iodide solution consisted of blocks of a few microns in size, while those from a sulfate solution exhibited grains smaller than 1 μm. The deposits containing Ag less than 45 mass% were composed of an Ag3Sn intermetallic compound and Sn. This is in accordance with the equilibrium phase diagram of the binary Ag-Sn system. The contact resistance of deposited Sn-Ag alloys, after heating at 433 K for 120h, was slightly smaller at Ag content below 45 mass% than that of reflow Sn plating. The connection reliability of connectors after abrasion was better in deposited films of Sn-Ag alloys than in those with reflow Sn plating.

    Original languageEnglish
    Pages (from-to)712-719
    Number of pages8
    JournalMaterials Transactions
    Issue number4
    Publication statusPublished - Apr 2010

    All Science Journal Classification (ASJC) codes

    • Materials Science(all)
    • Condensed Matter Physics
    • Mechanics of Materials
    • Mechanical Engineering


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