Trivalent gold cyanide-free gold plating solution based on coordination of heterocyclic alkaloids and its application

Abstract

The invention discloses a trivalent gold cyanide-free gold plating electroplating solution based on heterocyclic alkaloid coordination and application thereof. The electroplating solution comprises atrivalent gold salt, a coordination agent, a pH buffering agent, a mildew preventive and an additive, wherein taking chloroauric acid which provides trivalent gold as a main salt, and taking heterocyclic alkaloid as a coordination agent, and the mixture of anhydrous potassium carbonate and potassium dihydrogen phosphate is used as a pH buffer agent, sodium tetraborate or sodium benzoate or formaldehyde is used as a mildew preventive, and sulfur-containing organic matters are used as additives. According to trivalent gold cyanide-free gold plating electroplating solution based on heterocyclic alkaloid coordination and application thereof, the cyanide-free gold plating solution is convenient to source and outstanding in comprehensive performance; the plating solution has good plating resistance; the anti-replacement capability is high, and the phenomenon that the gold layer is replaced due to the fact that the fresh nickel plating piece is placed in the plating solution for 3 minutes isavoided; the binding force of the gold plating layer and the nickel and the copper substrate is good under the wide current density of the 0.1-1.2A / dm<2>, the brightness is high, and the color is uniform and golden; in addition, the method has the characteristic that the plating solution is simple to prepare, the gold plating process is convenient and controllable, and the like.

Description

technical field [0001] The invention belongs to the technical field of cyanide-free gold plating, and specifically relates to a trivalent gold cyanide-free gold plating solution based on heterocyclic alkaloid coordination and an application thereof. Background technique [0002] Gold electroplating is widely used in electrical appliances, connectors, printed circuit boards, integrated circuits and decoration fields. [0003] Common oxidation states of gold are trivalent and monovalent. During the reduction process of trivalent gold, first two electrons are obtained to reduce to monovalent gold, and then one electron is obtained to reduce to elemental gold. The reduction overpotential of simple and uncoordinated trivalent gold ions is small, and the resulting gold deposit particles are relatively coarse and may cause the inclusion of monovalent gold. In an aqueous solution without a complexing agent, monovalent gold is extremely prone to disproportionation reaction, turning...

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Problems solved by technology

In the above-mentioned monovalent gold cyanide-free gold plating process, the main salt or complexing agent contains sulfur, and the total amount used is large, and the obtained coating is easy to contain sulfur and may become brittle

[0008] In addition, due to the lack of stability of monovalent gold, some studies have used chloroauric acid as the main salt source, hypoxanthine as a complexing agent, and polyethyleneimine as an additive to a cyanide-free gold plating system. Although the stability of the electroplating solution has been improved, the The pH value of the system is high, which is easy to cause corrosion of electroplating equipment

[0009] In short, the current cyanide-free gold plating process or insufficient stability of the electroplating solution, or harsh electroplating conditions, or low-quality coatings, and easy-to-corrosion equipment all have defects that cannot meet the needs of electroplating processing.

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