Abstract Gold coating is one of the choices to prevent copper circuit in PCBs from corrosion. Although galvanic replacement deposition is supposed to be a convenient method to prepare gold coating on copper circuit, compact gold coating is hard to be obtained through traditional galvanic replacement deposition. In this work, gold coatings were prepared on copper substrates through traditional and modified galvanic replacement deposition. According to the SEM, EDS, XPS and XRD tests, the gold coating prepared by traditional galvanic replacement deposition had lots of micropores and nanopores, and Cu-Au solid solution phase was generated on copper substrate other than the gold phase. Therefore, the gold coating prepared by traditional galvanic replacement deposition could not prevent copper substrate from corrosion, but slightly increased the corrosion current density of copper substrate in 3.5 wt% NaCl solution owing to the galvanic corrosion. However, compact gold coating could be obtained through modified galvanic replacement deposition, in which aluminum foil was contacted to the copper substrate to form galvanic couple and donated the electrons for the deposition of gold instead of the copper substrate. The SEM, EDS, XPS and XRD tests demonstrated the gold coating prepared by modified galvanic replacement deposition was compact and mainly composed of pure gold phase. The gold coating prepared by modified galvanic replacement deposition obviously enhanced the corrosion resistance of copper substrate, and it reduced the corrosion current density of copper substrate in 3.5 wt% NaCl solution to 1.773 μA·cm−2 from 87.40 μA·cm−2 with the corrosion inhibition efficiency of 98.0%.

中文翻译：

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传统与改良电置换沉积法制备的金镀层防铜腐蚀的对比研究

摘要 镀金是防止PCB中铜电路腐蚀的一种选择。虽然电置换沉积被认为是一种在铜电路上制备金涂层的便捷方法，但通过传统的电置换沉积很难获得致密的金涂层。在这项工作中，通过传统和改进的电置换沉积在铜基材上制备了金涂层。SEM、EDS、XPS和XRD测试表明，传统电置换沉积制备的金涂层具有大量微孔和纳米孔，除金相外，在铜基体上还生成了Cu-Au固溶相。因此，传统的电置换沉积制备的金涂层不能防止铜基体腐蚀，但由于电偶腐蚀，铜基体在 3.5 wt% NaCl 溶液中的腐蚀电流密度略有增加。然而，通过改进的电置换沉积可以获得致密的金涂层，其中铝箔与铜基板接触形成电偶，并提供电子用于金而不是铜基板的沉积。SEM、EDS、XPS 和 XRD 测试表明，通过改性电置换沉积制备的金涂层致密且主要由纯金相组成。改性电置换沉积制备的金涂层显着提高了铜基体的耐腐蚀性能，使铜基体在3.5 wt% NaCl溶液中的腐蚀电流密度从87降至1.773 μA·cm-2。