Study On The Preparation And Properties Of Micro-Ag/nano-Ag-Cu Particles Mixed Solder Paste

Nano-Ag and nano-Cu are currently hot research topics in nano-interconnect materials,but Cu is prone to oxidation,and Ag’s resistance to electrochemical migration is too poor,which restricts the use of both.In addition,the elemental nano-material sintered body has the disadvantages of low density,poor conductivity,and poor thermal cycling resistance,and requires pressure to be applied during sintering and interconnection,which increases the process difficulty for the manufacture of electronic devices.Therefore,seeking a material that has both oxidation resistance and electromigration resistance has become an important research direction of nanointerconnect materials.This paper designs and prepares an Ag-Cu binary alloy nanoparticle with both oxidation resistance and electrochemical migration resistance.It also has excellent oxidation resistance and electromigration resistance.The preparation method is simple and the yield is high..The nano-particles and micro-Ag particles are used to prepare a micro-nano mixed solder paste,which has greatly improved the density,mechanical strength,electrical conductivity,and thermal conductivity compared with the traditional pure metal nano solder paste.Nano-Ag-Cu solid solution particles and micro-Ag particles were prepared by chemical liquid phase reduction method,and the effects of different raw material selection and process parameters on particle morphology and particle size were explored.It was found that when a strong reducing agent was used to simultaneously reduce AgNO₃ and Cu（NO₃）₂ and citric acid was used as the dispersant,nano Ag-Cu solid solution particles were obtained;when a weak reducing agent was used to reduce AgNO₃ and PVP was used as the dispersant,micron Ag particles was obtained.And different dropping methods and reaction temperature will have an important impact on the particle size and morphology of the particles.After the preparation of the particles was completed,the study of the oxidation resistance of the particles began.The results show that the nano-Ag-Cu solid solution particles have extremely strong oxidation resistance,and no oxidized phase is formed during storage for three months.The micro-nano mixed solder paste was prepared by mixing the micro-particles and nano-particles.The thermal performance test found that the sintering temperature was reduced,indicating that the addition of micro-Ag enhances the sintering driving force between the particles and thus helps the particles.Sintering.Micron and nanoparticles with different mixing ratios are used to prepare micronano mixed solder pastes to prepare Cu-Cu interconnect joints.Characterize the micromorphology of the sintered body and interconnection joints,and test and compare the shear strength,electrical conductivity,and thermal conductivity of the interconnection joints.The experimental results show that with the increase of the amount of micron Ag particles,the density of the sintered body,the mechanical strength,electrical conductivity and thermal conductivity of the interconnection joints are improved.When the amount of micron Ag added reaches 60% to 80%,the sintered state of the micronano mixed solder paste is the best,that is,the sintered state with the micro-particles as the support "framework" and the nano-particles as the "connection point",and does not need Apply pressure to sinter.