Composite Electroless Plating Is Used To Prepare Silver-coated Copper Powder With High Density And High Coverage

Silver-coated copper powder is a new type of composite material,it not only has the physicochemical properties of the copper powder,but also has the excellent metal characteristics of the silver coating layer,so that the composite powder has high electrical conductivity,oxidation resistance and thermal stability,and it overcomes silver migration defects of silver conductive adhesive.Achieving the goal of saving precious metals and reducing production costs.However,in the preparation technology of silver-coated copper powder,the density,coating rate and continuity of the silver coating have always been the key technical difficulties.A breakthrough in this technical difficulty direct ly affects the performance and application range of the silver-coated copper powder.C urrently known silver-coated copper powder can only be used in conductive shielding paints,low-temperature curing conductive pastes and other products,but can not meet the requirements of sintered paste.In this paper,spherical copper powder is used as the matrix material,and nano-composite electroless plating is adopted.Silver nanoparticles are added to the plating solution to co-deposit the silver ions with the silver nanoparticles,depositing a high density and high coverage silver layer on the surface of the copper powder,and an antioxidant and highly conductive silver-coated copper powder was obtained.This paper studied the effect of adding nanoparticles on the co-deposition of silver layer,screened and confirmed that the nano-silver particles were co-deposited nanoparticles;studied the effect of nano-silver concentration,stirring speed and temperature on the properties of silver-coated copper powder,using X-ray diffractometer(XRD),sca nning electron microscope(SEM),and digital ohmics characterize the phase composition,surface morphology,and electrical conductivity of silver-coated copper powder.Exploring the role of nano-silver in composite electroless plating and determining the best process conditions.A silver-coated copper powder with good oxidation resistance and good conductivity was prepared.Using the powder as the co nductive phase,an intermediate temperature sintered electrode slurry was prepared,and the performance was compared with the medium-temperature electrode silver paste to achieve the use requirements.Research indicates:(1)Comparing with the preparation method of three types of silver-coated copper powder without adding nanoparticles,adding nano-CeO2 and adding nano-Ag,the silver-coated copper powder prepared by adding nano-Ag has the best performance.(2)The effects of different process conditions on the properties of silver-coated copper powders were investigated.The process conditions were as follows: nano-Ag concentration 1 g/L,stirring speed 1000 r/min,and temperature 30°C.The silver-coated copper powder was prepared as high density,high coverage,strong anti-oxidation ability and good conductivity.(3)Using an optimized process,lengthening the reaction time and increasing the reaction temperature,effectively improved the yield of silver-coated copper powder.(4)Preparation of silver-coated copper powder by composite electroless plating: nano-Ag can effectively increase nucleation sites,compensate for crystal defects,and reduce porosity.The resulting silver coating has good compactness,high coverage,and the plating effect is significantly better than that without adding nano-Ag.When nano-Ag is added,silver-coated copper powder has good oxidation resistance and conductivity.(5)The electrode slurry prepared by high density and high coverage silver-coated copper powder has good conductivity,high stability and excellent practical value.