Method for copper powder displacement for chemical silver plating

Abstract

The invention discloses a method for displacement chemical silver plating on copper powder. The method comprises the following steps of: cleaning and oil removal, water washing, acid etching, water washing, catalytic liquid treating, chemical silver plating and the like. In the method, a catalytic liquid capable of preplanting catalytic mass points is developed; the surface of the copper powder is preplanted with discretely distributed palladium mass points after the copper powder is treated by the catalytic liquid at a room temperature by controlling components, pH value and treatment time of the catalytic liquid; and the preplanted palladium mass points can catalyze and promote the silver ion reduction to improve precipitation speed and to retard copper-ammonia complex ions to be absorbed on the copper surface so as to obtain a sliver plating layer with good cladding performance in the chemical silver-plating process for the copper powder. Compared with the conventional method of displacement chemical silver plating, the method realizes surface activation of the copper powder by pretreating the catalytic liquid, a silver content of the silver plating copper powder is greatly improved, the problems of poor cladding performance of replacement type chemical silver plating and the like are solved, and the method is simple in process and convenient to operate and has good application prospect.

Description

technical field [0001] The invention relates to copper powder surface treatment technology, in particular to a method for copper powder to replace chemical silver plating; the silver-plated copper powder prepared by this method has good coating performance and can be widely used in various electromagnetic shielding fillers, conductive adhesives, conductive in paint. Background technique [0002] Cu-Ag metal powder can be widely used in fields such as electronic paste, electromagnetic shielding material and catalyst. At present, there are two commonly used chemical methods for preparing Cu-Ag metal powder: one is to directly use copper powder as a reducing agent to replace silver ammonia coordination ions to obtain silver particles, which are deposited on the surface of copper powder. The current research mainly adopts this method, but most of this kind of deposition forms a dotted coating structure. Copper has a strong adsorption effect on cuproammonia complex ions, which h...

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Problems solved by technology

[0005] Aiming at the strong adsorption effect of copper on cuproammonia complex ions in the replacement method, which hinders the further replacement of copper, resulting in poor coating of the silver plating layer and other problems

The present invention combines the advantages of the two methods, and proposes to use palladium with strong catalytic activity on the surface of the copper powder to form a catalytic center, promote the reduction and deposition of silver ions in the silver plating solution, and hinder the adsorption of copper ammonia complex ions on the copper surface, thereby Obtain a continuous silver plating layer, which greatly improves the density and silver content of the plating layer, and solves the problems of cumbersome processes of other displacement silver plating methods, easy decomposition of the plating solution of the reducing agent silver plating method, and non-environmental protection.

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