Gold-silver-rhodium multilayer composite plating process

Abstract

The invention provides a gold-silver-rhodium multilayer composite plating process. According to the process, a rhodanizing coating does not crack, bubbling, peeling and falling off of each plating can be avoided, platings are well combined and do not discolor, the service life is high, and movement of a silver plating can be effectively constrained at a high temperature. According to the technical scheme, a cyaniding pre-silver-plating process is added before gold plating, a 3ml / L-8ml / L of cyaniding silver plating solution is added in a cyaniding tank, a reversing power supply is adopted after cyaniding, and a thin silver layer is plated reversely in the solution, after the cyaniding pre-silver-plating process, citrate is adopted for gold plating; after the gold plating, silver is plated through cyaniding, rhodium is plated through phosphate, after the rhodium plating, vacuum annealing heat treatment is performed at the temperature of 900-950 DEG C to evenly coat the three precious metal of the gold, the silver and the rhodium on the surface of a part. According to the process, under the condition that a rhodium plating of a contact type switching element such as a reed switch can not be welded, one end of a workpiece can be welded with a wire or sealed with glass, and bubbles, cracks and air tightness problems are not easy to cause.

Description

technical field [0001] The invention relates to a surface treatment technology for multi-layer precious metal gold, silver and rhodium electroplating, and is mainly aimed at the surface treatment method of the elastic reed of a reed switch. Background technique [0002] The multi-layer precious metal gold, silver and rhodium electroplating surface treatment process is a relatively complicated and costly process treatment method. Among them, technical parameters such as the electroplating solution formula, electroplating solution pH value, electroplating temperature, electroplating time, electrode current density and so on gold plating, silver plating process and rhodium plating process all have special requirements. To obtain the technical parameters of the precious metal gold, silver and rhodium multilayer composite electroplating process needs to pass through a long time, even many times of experiments. Multi-layer precious metal gold, silver and rhodium electroplating mu...

AI Technical Summary

Problems solved by technology

[0008] 3. Nickel-silver-platinum-rhodium multi-layer composite electroplating process uses nickel as the bottom layer of the silver layer. Because the hardness of nickel is high, it cannot restrain the running of the silver layer at high temperature. If the workpiece after nickel plating and silver plating is sealed with glass, it will And under high and low air pressure, the sealing head will crack, which will not be airtight, which will affect the reliability of the product

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