Cyanide-free silver plating liquid composition based on composite coordination system and application of cyanide-free silver plating liquid composition

Abstract

The invention discloses a cyanide-free silver plating liquid composition based on a composite coordination system and application of the cyanide-free silver plating liquid composition. pH=8.5-12.5. The cyanide-free silver plating liquid composition comprises silver salt, a coordination agent, conducting salt, a pH buffer agent, an adding agent and deionized water. The coordination agent is formedby a first coordination agent, a second coordination agent and a third coordination agent. The total molar concentration ranges from 0.25 mol / L to 2.8 mol / L. The molar ratio of the silver salt to thecoordination agent is 1:5-8. The cyanide-free silver plating liquid composition is quite stable, a solution is still transparent after being put for half a year, scanning electrochemical curves are basically overlapped, plating liquid components are basically not changed, the displacement resisting capacity is high, a silver replacement layer cannot be observed when an activated copper sheet is put in silver liquid for 3 min, the depth capacity and the covering capacity are good, and silver plating layers be obtained for parts in complex shapes or with deep holes in an electroplating manner; and a cyanide-free silver plating method is based on the composite coordination system, the proper multi-coordination system is selected, the comprehensive performance is close to and even superior tothat of the cyaniding silver plating process, and the industrial application foundation is achieved.

Description

technical field [0001] The invention belongs to the technical field of electroplating precious metals, and in particular relates to a cyanide-free silver plating solution composition based on a composite coordination system and an application thereof. Background technique [0002] Silver has many uses in industry as well as in everyday life. Silver has good electrical and thermal conductivity and good welding performance, and has important applications in the electronics industry; silver has sterilization properties and good electrical conductivity, so it is often used in medical devices and sensors; silver has a pleasing appearance, and is often used in decorations Such as jewelry, tableware, etc. In addition to pure silver devices, electroplating metal silver on the surface of metal devices also gives the device the characteristics of silver. [0003] Cyanide silver plating is a mature electroplating process. Cyanide and silver have strong coordination ability and can f...

AI Technical Summary

Problems solved by technology

Although the stability of the plating solution has been partially improved, its allowable current density range is narrow, and the thickness of the plating layer on the surface of parts with complex shapes is not uniform; the plating solution contains phosphorus, and wastewater treatment will be troublesome

[0008] Most cyanide-free silver plating systems use thiosulfate, nicotinic acid, succinimide, hydantoin and their derivatives as complexing agents, but there are some common problems in these systems: such as the allowable current density range Narrow, difficult to increase plating speed, obvious color difference of coating, poor stability of plating solution, overall properties of coating such as hardness, anti-tarnish performance and binding force need to be further stabilized and improved, difficult to adjust plating solution during production, etc.

In short, although the current cyanide-free silver plating process has its own characteristics, there are also defects that make it unable to meet the needs of electroplating processing.

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