2002 Fiscal Year Final Research Report Summary
Research on non-cyanide electroless gold plating reactions for sustainable use
| Project/Area Number |
13650880
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
工業物理化学
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| Research Institution | Yokohama National University |
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Principal Investigator |
IMABAYASHI Shin-ichiro Yokohama National University, Faculty of Engineering, Associate Professor, 大学院・工学研究院, 助教授 (50251757)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Electroless gold plating / Non-cyanide / Sustainable use / Sulfite / Thiosulfate / Thiourea / Hydroquinone |
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| Research Abstract |
Aiming to establish non-cyanide electroless gold plating reactions for sustainable use, I have investigated redox reactions in the plating solution containing sulfite (SO_3^<2->) and thiosulfate as ligands for Au(I) ion, thiourea (TU) as a reducing agent, and hydroquinone (HQ). The following results were obtained
1) In the course of the plating reaction, HQ is oxidized to benzoquinone (Q) by thiyl radical which is a product of the reaction between Au(I) complex and TU, followed by the formation of hydroquinone sulfonic acid (HQSA) through the reaction between S0_3^<2-> and Q.HQSA is further sulfonated according to a similar reaction mechanism to that of HQ
2) It was found that TU is able to accelerate the reduction of Au(I) complexes. This acceleration is specifically observed on the gold electrode surface, not on glassy carbon (GC) electrodes
3) The possibility of the electrochemical desulfonation of HQSA was assessed in aqueous buffers (pH 5, 8) and organic solvents (DMSO, DMF) using Au, GC, Pt, and Au amalgam electrodes. The desulfonation reaction did not occur within the potential windows of these solvent-electrode systems
4) The supply of Au(I) complex as [Au(SO_3^<2->)_2]^<3-> during the plating was recommended, since the increase in the concentration of SO_3^<2-> in the plating solution, which is caused by the supply of [Au(SO_3^<2->)_2]^<3->, does not significantly affect the reduction of Au(I) complex
5) I proposed a new approach toward the establishment of the non-cyanide electroless gold plating reaction for sustainable use, in which dimethyl disulfonyl hydroquinone is used instead of HQ
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