Method for displacement chemical silver plating on copper powder

A technology of electroless silver plating and copper powder, applied in liquid chemical plating, coating, metal material coating process, etc. The problem of further replacement of copper, etc., achieves the effect of promoting reduction deposition, improving compactness and silver content, and simple composition

Inactive Publication Date: 2010-05-19
GUANGDONG UNIV OF TECH
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  • Abstract
  • Description
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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.

Method used

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  • Method for displacement chemical silver plating on copper powder
  • Method for displacement chemical silver plating on copper powder

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0032] 1) Clean and degrease the 200-mesh copper powder at room temperature, rinse with distilled water

[0033] 2) Use a nitric acid solution containing 5wt% at room temperature until the oxides on the surface of 75 grams of 200-mesh copper powder are removed, and rinse with distilled water;

[0034] 3) Put the pickled copper powder into a catalytic solution consisting of 0.035g / L palladium chloride and 20g / L hydrochloric acid, and wash it repeatedly with distilled water after 30 minutes at room temperature until the filtrate does not contain Cl - up to ions;

[0035] 4) Configure electroless silver plating solution: 28g / L silver nitrate, 60g / L trisodium citrate and triethylenetetramine mixed complexing agent, use ammonia water and sodium hydroxide to adjust the pH of the silver plating solution to 10.5;

[0036] 5) Put the activated copper powder into the silver plating solution, and react with electromagnetic stirring for 20 minutes

[0037] 6) Stop plating, wash and filt...

Embodiment 2

[0040] 1) Clean and degrease the 200-mesh copper powder at room temperature, rinse with distilled water

[0041] 2) Use a sulfuric acid solution containing 7wt% at room temperature until the oxides on the surface of 65 grams of 200-mesh copper powder are removed, and rinse with distilled water;

[0042] 3) Put the acid-washed copper powder into a catalytic solution composed of 0.098g / L palladium chloride, 25g / L hydrochloric acid and citric acid. Containing Cl- ions;

[0043] 4) Configure the electroless silver plating solution: 34g / L silver nitrate, 110g / L sodium lactate and ethylenediamine mixed complexing agent, use ammonia water and sodium hydroxide to adjust the pH of the silver plating solution to 12.5;

[0044] 5) Put the activated copper powder into the silver plating solution, mechanically stir and react for 20min

[0045] 6) Stop plating, wash and filter the silver-plated copper powder, and dry it under vacuum at 100°C.

[0046] The obtained silver-plated copper po...

Embodiment 3

[0048] 1) Clean and degrease the 400-mesh copper powder at room temperature, rinse with distilled water

[0049] 2) Use phosphoric acid solution containing 9.5wt% at room temperature until the oxide on the surface of 15 grams of 400 mesh copper powder is removed, and rinse with distilled water;

[0050]3) Put the pickled copper powder into an activation solution consisting of 0.130g / L palladium dichlorotetraammine and 15g / L ammonia water. After 10 minutes of treatment at room temperature, use distilled water to wash repeatedly until the filtrate does not contain Cl- ion so far;

[0051] 4) Configure an electroless silver plating solution: a mixed complexing agent of 25g / L silver nitrate, 96g / L sodium lactate and tetraethylenepentamine, use ammonia water and sodium hydroxide to adjust the pH of the silver plating solution to 13;

[0052] 5) Put the activated copper powder into the silver-plating solution, and stir it mechanically and electromagnetically for 20 minutes;

[005...

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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...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C18/44B22F1/02
Inventor 胡永俊张海燕成晓玲胡光辉李风陈天立曾国勋
Owner GUANGDONG UNIV OF TECH
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