Preparation And Characterizations Of Low Temperature Co-fired Ceramic Electronic Paste

Due to the rapid development of information technology,people have higher and higher requirements for electronic components(Especially in low temperature co-fired ceramics ‘Low temperature co-fired ceramics’,‘LTCC’),miniaturization and high-density requirements.And silver paste plays a very important role in electronic components.Because of its excellent electrical conductivity and stability,silver paste has received widespread attention and become the focus of research.The research on silver paste abroad has been very mature,but the domestic silver paste is only in the stage of rapid development.The country has also invested a lot of money in the research of silver paste.In order to break the foreign technology monopoly,the preparation technology and properties of silver paste were studied in this thesis.In this thesis,the liquid phase reduction method is used to prepare silver powders,silver nitrate is used as the silver precursor,ascorbic acid as the reducing agent,ammonia and nitric acid as p H regulators,gelatin,PVP,PVA,trisodium citrate,Tween80,oleic acid as a surfactant to prepare ultrafine silver powders.At the same time,a highly dispersible silver powder is prepared by means of sonification.The experimental results showed that when the concentration of silver nitrate was 50g/L,ascorbic acid was 25g/L,and the content of gelatin was 2wt.%,ammonia and nitric acid were used as p H regulators to adjust the p H of the reaction solution.It was found that silver powder prepared with three kinds of surfactants: gelatin,PVP and PVA had high dispersion performance after ultrasonic treatment,and the particle size distribution was uniform,all in the range of 500-1000 nm.As an important part of silver paste,organic carrier mainly affects the rheological properties,thixotropic properties,screen printing properties and many other properties of silver paste.This thesis studied the influence of the relative content of ethyl cellulose,acrylic resin,dioctyl phthalate,and dibutyl phthalate on the viscosity,thixotropy,yield stress and recovery properties of organic vehicles.When the content of ethyl cellulose was 12 wt.%,the content of acrylic resin was 2wt.%,and the ratio of dioctyl phthalate to dibutyl phthalate is 6:4,it has suitable viscosity,thixotropy,yield stress and recovery performance.Finally,the prepared silver powder,glass powder,and organic carrier were used to prepare silver paste by stirring and ball milling.The effects of adding different surfactants and thixotropic agents to the organic carrier on the viscosity,thixotropy and recovery properties of the organic carrier were aslo studied.The surfactants used are tributyl phosphate,Span85,castor oil and polymethacrylate amine(APMAA),and the thixotropic agents are hydrogenated castor oil,palmitic acid,furoic acid,stearylamine,corn oil,acrylic resin and Triolein.When the content of silver powder is78 wt.%,glass powder is 3wt.%,organic carrier is 1.84 wt.%,and alumina is 0.6wt.%,PVP and Span85 as surfactants have good performance.Its resistivity is 0.11mΩ·mm.When the thixotropic agent is hydrogenated castor oil and its content is 2wt.%,it has better thixotropic properties and better recovery property...