Size Controlled Preparation And Low Temperature Sintering Of Nano Copper Powder For Semiconductor Package Interconnection

The application of third-generation semiconductors on high-power devices faces the reliability test of high temperature,high voltage,high frequency and high heat dissipation,and also challenges the materials and processes of package interconnection.Traditional package interconnect materials mainly use solder paste or conductive paste,but they can not meet the requirements of high-power devices.Therefore,nano-metal materials with unique physical and chemical properties have become the research hotspot of current package interconnect materials.After the sintering of nano-metals,the melting point,electrical conductivity and thermal conductivity of the bulk metal are close to meet the working environment of hightemperature service.At present,nano-metal silver and copper are ideal high-power device interconnection materials.Because nano-silver is expensive and has the disadvantage of electromigration,it cannot be mass-produced and used.The cost of nano-copper is relatively low,but the oxidation resistance is poor.It greatly limits its sintering properties and applications.Therefore,a new preparation method of nano-copper particles is proposed in this subject system.The effects of different experimental parameters on the particle size,morphology and dispersibility of nano-copper are studied.The optimal preparation parameters are obtained and analyzed.The nano-copper powder was characterized by low-temperature sintering performance,and the optimal sintering parameters were obtained.In this paper,nano-copper particles were prepared by liquid phase reduction method.The slightly soluble copper salt-copper acetate monohydrate,reducing agent ascorbic acid and protective agent polyvinylpyrrolidone K30 were selected to reduce the concentration of copper salt and reducing agent and protective agent.The molar ratio,reaction temperature and reaction time were analyzed to determine the optimum experimental conditions for the preparation of nano-copper particles.When the molar ratio of copper acetate to ascorbic acid and polyvinylpyrrolidone K30 was 1:4 and 1:2,respectively,the average size of the obtained nano copper particles was 60 nm.At the same time,the preparation of nano-copper particles by polyvinylpyrrolidone and 2-phenylimidazole as double-protecting agents was investigated.It was found that when the concentration ratio of 2-phenylimidazole to PVP was 1:6,the average size of the particles reached a minimum of 85 nm.The morphology,size,oxidation resistance and decomposition temperature of surface organic matter were analyzed by SEM,XRD,UV-Vis absorption spectroscopy and thermogravimetric curves of nanoparticles.Explore the best nanocopper configuration and sintering scheme for copper-copper interconnects in chip package interconnects.The suitable solvent is mixed with the nano copper powder to form 60%,70% and 80% nano-copper pastes,and the nano-copper paste is printed on a single-sided titanium-plated copper wafer for sintering.Good nano copper paste solid content.At the same time,the nano copper paste is sintered at 220 ° C,260 ° C,and 300 ° C to obtain the optimum sintering temperature.The SEM image and shear force of the sintered sample were analyzed.The experimental results show that the solid content is 80%,and the sintering effect at 300 ? is the best.