クエン酸アンモニウム-ヨウ化カリウム浴からのSn-Ag合金めっきにおけるアノードの挙動 Anode Behaviors in Sn-Ag Alloy Plating from Ammonium Citrate-potassium Iodide Baths
Anodic current density-potential curves of Sn, Ag, Pt, and graphite were measured to obtain informations on the selection of anode materials in ammonium citrate-potassium iodide baths for Sn-Ag alloy plating. The Sn anode was dissolved at small overpotentials in ammonium citrate solutions containing iodide and showed a very smooth electrode surface. However, a displacement deposition of rough Ag was observed when solutions contained Ag<sup>+</sup>. The Ag anode also dissolved at small overpotentials. Nevertheless, AgI was precipitated at the anode and therefore the limiting current densities were smaller than 10mA/cm<sup>2</sup>. The main electrode reaction at the Pt and graphite anode was oxidation of iodide to form I<sub>3</sub><sup>-</sup>. This reaction also occurred at the Sn and Ag anode at high overpotentials. Sn<sup>2+</sup> species was chemically oxidized by I<sub>3</sub><sup>-</sup> formed at the anode, accumulating Sn<sup>4+</sup> species in baths. To prevent both Ag displacement deposition and anodic oxidation of iodide, the electrode potential of the anode in Sn-Ag alloy plating baths must be maintained between -0.2V and 0.4V vs. NHE.
- 表面技術 = The Journal of the Surface Finishing Society of Japan
表面技術 = The Journal of the Surface Finishing Society of Japan 49(12), 1316-1321, 1998-12-01
The Surface Finishing Society of Japan