Preparation Technology And Application Of Micro-nano Silver Powder Conductive Materials

Micro and nano silver powders are widely used in electronic devices,screen printing and biological antibacterial applications for their excellent electrical,optical,catalytic and antibacterial properties,and have become popular research materials.It is found that the performance of micro-nano silver powder is closely related to its morphology,particle size and dispersibility.Therefore,it is of great significance to study the preparation process of micro and nano silver powder and to control the production process and shape of micro and nano silver powder.This thesis uses the liquid-phase chemical reduction method to prepare micro-nano silver powder,to investigate the preparation process of micro-nano silver powder,and the application study of micro-nano silver powder,and to compare the use performance of silver powder in flake and micro-nano silver powder.A study of the preparation process of micro-nano silver powder shows that the concentration of silver nitrate has a significant effect on the particle size of micro-nano silver powder.For micron silver powders,reducing the concentration of silver nitrate results in a uniform particle size distribution of the silver powder;For silver nanopowders,too low a concentration of silver nitrate can lead to agglomeration between particles.The dispersant directly affects the dispersion of the silver powder,too little dispersant will not achieve the site resistance effect,too much will make the post-processing more difficult;The p H of the solution has an important influence on the morphology and properties of the micron silver powder.For the preparation of micron silver powder by chemical reduction,ascorbic acid was chosen as the reducing agent and the prepared solution was acidic,In contrast to the chemical reduction method for the preparation of silver nanopowders,sodium borohydride was used as the reducing agent,and good properties can only be obtained under alkaline conditions.The experimental results showed that silver nanopowders with a particle size of40 nm were obtained at a temperature of 50°C,a PVP concentration of 0.3 g·L^-1,a silver nitrate concentration of 0.2 mol/L,a p H value of 11,ultrasonic cleaning and mechanical stirring for 20 min,with good dispersion and uniform particle size distribution.The experimentally produced micron silver powder was used to prepare conductive adhesive fillers,and its properties and applications were investigated.The micron silver powder was made into flake silver powder using a ball milling process,and the differences in the properties of the flake silver powder obtained with different ball milling aids were investigated,with the best performance of the flake silver powder obtained using oleic acid as a grinding aid.The effect of different fillers on the performance of conductive adhesives was studied and analyzed by putting silver flake powder and mixed fillers into conductive adhesives,The experimental results show that:The use of mixed silver flake powder and nano-silver powder as a conductive filler,the addition of nano-silver powder improves the conductivity of the conductive adhesive to enhance,due to the small size of the nano-silver powder can fill in the gaps in the flake silver powder,which helps to form a conductive pathway in the conductive adhesive,when the conductive adhesive containing nano-silver powder at 120℃heating and curing,the nano-silver powder will melt,the conductive adhesive will be connected to the flake silver powder,the formation of a stable conductive pathway,thereby enhancing the stability of the conductive adhesive,shear resistance and adhesive strength,to obtain good mechanical properties.