Alkaline cyanide-free silver plating electroplating liquid and silver plating method

Abstract

The invention relates to alkaline cyanide-free silver plating electroplating liquid and a silver plating method. The electroplating liquid is composed of the following components including 20 g / L-50 g / L of silver nitrate, 40 g / L-100 g / L of 5,5-dimethyl hydantoin, 70 g / L-100 g / L of potassium pyrophosphate, 0.8 g / L-1.2 g / L of 3,3'-dithiobis-1-propanesulfonic acid disodium salt, 0.10 g / L-0.15 g / L of benzotriazole, 10 mg / L-15 mg / L of N,N'-bi-oleoyl-Ethylenediamine-Sodium Diethyl sulfonate, 0.10 g / L-0.30 g / L of polyethylene glycol and the balance water, wherein due to a pH adjusting agent, the pH value of the system ranges from 8 to 12. By means of the alkaline cyanide-free silver plating electroplating liquid, all the components are matched and work collaboratively, stability is good, the copper replacement resisting performance is high, and the scattering capability of the plating liquid is high; crystal grains of a silver plated layer are fine, the crystal grains are densely and neatly arranged, the surface is flat and bright, glossiness is good, and the color changing resisting capability is high; and the hardness of the plated layer is high, the combining force with a base body is high, and the alkaline cyanide-free silver plating electroplating liquid is suitable for application and popularization.

Description

technical field [0001] The invention belongs to the technical field of electroplating silver, and in particular relates to an alkaline cyanide-free silver-plating solution, and also relates to a silver-plating method using the alkaline cyanide-free silver-plating solution. Background technique [0002] Electroplating technology, also known as electrodeposition, is one of the main methods to obtain metal coatings on the appearance of raw materials. It uses a direct current electric field to make the cathode and anode in the electrolyte solution (plating solution) form a circuit, so that the metal cations in the electrolyte move to the cathode. And the process of losing ions and reducing them to simple metals and then depositing on the surface of the plated parts. Among them, the electroplated silver layer is widely used in electronic engineering, decoration and other fields due to its unique silvery white luster, good electrical and thermal conductivity, ductility and brazing...

AI Technical Summary

Problems solved by technology

[0004] In the existing common cyanide-free silver plating process, the crystallization of the coating obtained by the thiosulfate silver plating system is fine and bright, the coating is silvery white, and has good anti-tarnish ability, but the coating contains a small amount of impurity sulfur, which affects its hardness and conductivity. , the allowable range of cathode current density is narrow

Ammonium iminodisulfonate silver plating (NS silver plating) system has simple components, the coating crystal is fine and bright, and the covering ability is close to that of cyanide silver plating solution, but the ammonia in the solution is easy to volatilize, the pH value is easy to change, and the presence of iron impurities It is easy to change the color of the plating solution and the bright area becomes smaller

The succinimide silver plating system has a wide pH value range and high gloss of the coating, but the disadvantage is that the succinimide complexing agent is prone to hydrolysis, and the anti-discoloration ability of the silver plating layer becomes poor.

5,5 dimethylhydantoin is selected as the complexing agent in the cyanide-free silver plating solution, the plating solution is stable, but the bonding force between the plating layer and the substrate is not strong, the plating layer is prone to fogging, and the brightness and hardness are not enough, which affects its use

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