Research on non-cyanide electroless gold plating reactions for sustainable use

可持续利用的无氰化学镀金反应研究

• 批准号: 13650880
• 负责人: IMABAYASHI Shin-ichiro
• 金额: $ 2.3万
• 依托单位: Yokohama National University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650880/
• 关键词: Electroless gold plating; Non-cyanide; Sustainable use; Sulfite; Thiosulfate; Thiourea; Hydroquinone; 無電解金メッキ; 亜硫酸ナトリウム; チオ硫酸ナトリウム

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 obtained1) 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 HQ2) 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) electrodes3) 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 systems4) 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) complex5) 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

为了建立可持续使用的无氰化学镀金反应，我研究了在含有亚硫酸盐（SO_3^<2->）和硫代硫酸盐作为Au（I）离子配体、硫脲（TU）作为还原剂和对苯二酚（HQ）的镀液中的氧化还原反应。结果表明：（1）在电镀反应过程中，Au（I）配合物与TU反应生成的巯基自由基将HQ氧化为苯醌（Q），然后SO_3 ~（2-）与Q反应生成氢醌磺酸（HQSA），HQSA进一步磺化的反应机理与HQ相似<2->;结果表明，TU能加速Au（I）配合物的还原。这种加速在金电极表面上特别观察到，而不是在玻璃碳（GC）电极上3）使用Au、GC、Pt和Au汞齐电极在水性缓冲液（pH 5、8）和有机溶剂（DMSO、DMF）中评估HQSA电化学磺化的可能性。4）由于[Au（SO_3<2->）_2]^<3->引起的镀液中SO_3 ~-浓度的增加对Au（I）络合物的还原没有显著影响，因此推荐<2->在镀液中以[Au（SO_3<2->）_2]^<3->的形式提供Au（I）络合物