Study On Technology Of Ultra-fine Silver Coated Copper Powder

Ultra-fine silver-coated copper powder can give full play to the high conductivity of silver and antioxidant properties,improve the physical and chemical properties of ultra-fine copper powder,reduce the application cost of pure silver powder.Therefore,ultra-fine silver-coated copper powder is more and more research in the application of conductive coatings,conductive plastic products.However,ultra-fine silver-coated copper powder in the application there is still insufficient conductivity,poor oxidation resistance of the shortcomings,and domestic products and some foreign companies compared to the product there are some deficiencies.Therefore,the purpose of this project is to study the preparation process of silver-coated copper powder,improve the performance of powder,fill the shortcomings of high-performance ultra-fine silver-coated copper powder in the market,and replace foreign related products.The significance of the implementation of this subject is that after the silver coating of ultra-fine copper powder,not only can improve the oxidation resistance of copper powder,conductivity,expand the application of ultra-fine electrolytic copper powder,and can replace the silver powder,to meet the electromagnetic shielding,conductive filler,conductive adhesives and other areas of the demand has important value.In this paper,the ultra-fine electrolytic copper powder was used as raw material.By analyzing the experimental principle and experimental results of direct replacement and chemical reduction method,the process of preparing superfine silver-coated copper powder by composite method was determined.The effect of dispersant and reducing agent on the properties of the powder was studied by optimizing the experimental method.The complex dispersant and reducing agent were determined.The pH value and the addition rate of silver ammonia were also studied.The structure and properties of ultra-fine silver-coated copper powder were analyzed by scanning electron microscopy,energy dispersive spectrometer,X-ray diffractometer,oxygen content tester,laser particle size analyzer and thermogravimetric analyzer.At the same time,Ultra-fine silver-clad copper powder products in the performance of a comparative study.Finally,the application of ultra-fine silver-clad copper powder in conductive adhesive was studied,and the performance and structure of conductive adhesive using different conductive powder as conductive filler were compared.The following conclusions are drawn:(1)In this experiment,ultra-fine electrolytic copper powder was selected as raw material for silver plating.By comparing the different electroless plating methods,this paper has a kind of replacement silver pre-silver and chemical reduction combined with the preparation of ultra-fine silver-coated copper powder.(2)Through the experimental analysis of the chemical reagents used in the preparation of ultra-fine silver-coated copper powder,the main reagents in the powder preparation process were determined as follows:a certain amount of EDTA-2Na was used as complex dispersant,potassium tartrate as a reductant is more appropriate;through the adjustment of the parameters of the process to determine the preparation of ultra-fine silver-coated copper powder in the process parameters are:the system temperature of 30?,the pH is 9?10,the bath concentration is 0.4mol/L,The bath adding rate is 8 mL/min.(3)The analysis of the structure of the powder shows that the powder particles are dispersed uniformly and the surface is smooth.The prepared ultra-fine silver-coated copper powder has a complete coating structure and the coating structure is uniform and compact.The silver coating of the powder can reach a certain thickness.The results show that the self-made powder has a lower oxygen content and a resistivity than that of a certain product in the market.The anti-oxidation performance of the coated powder is higher than that of the raw material copper powder.The results of thermogravimetric analysis show that the superfine silver anti-oxidation performance of copper-clad powder is better than that of raw copper powder and silver powder.(4)The conductive adhesive prepared by different conductive powder can be used to analyze the structure and performance of the conductive adhesive.The prepared ultra-fine silver-coated copper powder has good conductivity after the preparation of conductive adhesive,and has reached the market.The performance of some of the flake-like silver-coated copper powder;through the SEM picture can be seen that the prepared powder can be better in the conductive adhesive dispersion,play a conductive role.