Preparation of the micrometer-scale silver-coated copper powder by electroless plating with replacement reaction

The micrometer-scale silver-coated copper powder was prepared by a novel replacement chemical plating. Compared with the traditional chemical plating, further study on the application of silver coated copper powder in conductive adhesive. By changing the plating solution temperature, a series of silver loading curves from 10 ℃ to 60 ℃ were obtained respectively, from which a series of the rate constants of the replacement reaction at different temperatures were deduced with a theoretical fitting to the surface reaction kinetics. By fitting the Arrhenius equation, the activation energy of replacement reaction was achieved to be 4.1×104 J/mol. The morphology and crystal structure of the silver-coated copper powder were investigated by SEM and XRD, and the surface coverage of the prepared sample was tested by an immersion in a 20% HNO3 solution. It demonstrated that the copper powder can be completely covered by silver while the replacement reaction time is longer than 3 h. The thermogravimetric analysis proved that the silver coating can significantly improve the oxidation resistance of the material. The silver-coated copper powder and epoxy resin prepared at 40 ℃ are used to make 55% conductive adhesive. The results showed that the sample resistance keeps stable at a resistance of less than 0.8 Ω within 40 h baking, although it has a slight increase hereafter due to the thermal diffusion of the copper atoms to the particle surface. The results provided in the present manuscript show great potential in the practical application. © 2021, Chongqing Wujiu Periodicals Press. All rights reserved.