采用液相化学还原法制备出平均粒径为20--35nm的纳米银,并考察不同温度及PVP用量对纳米银性质的影响。结果表明:当硝酸银与PVP的质量比为1∶4、反应温度为30℃时,纳米银的平均粒径最小,为22.4nm,且其团聚程度最小,粒径分布最佳。在压力10MPa、温度200℃、保温30min的烧结条件下,利用制得的纳米银配制焊膏,连接纯度为99.9%的无氧紫铜板,通过扫描电镜(SEM)观察烧结接头截面形貌,可见烧结界面连接紧密,接头组织有孔隙存在。
Silver nanoparticles with average diameter of 20-35 nm were prepared by aqueous reduction method,and the influence factors of nanoparticles characteristics,such as reaction temperature and PVP concentration,were investigated during reduction process.The results show that monodispersity of nanoparticles is remarkably improved while unfavorable agglomeration is avoided with the AgNO3/PVP mass ratio of 1∶4at the reaction temperature 30℃,and the average diameter of silver nanoparticles reaches the mininum of 22.4nm.Copper pads with the purity of 99.9%are successfully bonded at200℃ and under the pressure of 10 MPa for 30 min,using sintering paste employing fresh silver nanoparticles.Morphology of the bonding joint is analyzed with scanning electron microscope(SEM),the interface is compacted tightly and porous sintering characteristic is confirmed.