中文摘要：

利用液相法合成均径为57.5 nm的纳米铜颗粒,并对纳米铜颗粒进行系统的表征,包括有扫描电子显微镜（Scanning electron microscope,SEM）、透射电子显微镜（Transmission electron microscope,TEM）、X射线衍射（X-ray diffraction,XRD）以及热重分析（Thermal gravity analysis,TGA）和差热分析（Differential thermal analysis,DTA）,并利用超声手段将纳米铜颗粒均匀分散在水溶液中,从而得到了纳米铜焊膏。采取模板印刷的方法制备镍/纳米铜焊膏/铜的三明治结构,并研究不同脉冲电流烧结工艺下的三明治结构的剪切强度、截面微结构以及断口微结构特征。试验结果表明三明治结构的剪切强度随着电流的增加而增大,在电流为0.8 k A时,剪切强度可达到46.3 MPa,脉冲电流烧结纳米铜焊膏连接铜和镍基板在短时间（小于200 ms）内快速获得了高致密度、性能优良的焊点结构,同时纳米铜颗粒之间以及纳米铜颗粒与微米级的铜基板和镍基板之间实现了牢固的冶金连接。通过分析经脉冲电流烧结后得到的纳米铜焊膏内部的显微组织特征,提出了脉冲电流烧结纳米铜焊膏的烧结机理。

英文摘要：

A simple solution method to synthesize Cu nanoparticles with the mean diameter of 57.5 nm is developed, and as-synthesized Cu nanoparticles are characterized systematically, including scanning electron microscope（SEM）, transmission electron microscope（TEM）, X-ray diffraction（XRD）, thermal gravity analysis（TGA） and differential thermal analysis（DTA）. The nano copper paste is prepared by dispensing as-prepared Cu nanoparticles into deionized water with the assistance of ultrasonic. The sandwich structure of nickel/nano copper paste/copper is fabricated using a simple screen-printing method and the shear strength of the sandwich structure, the cross-sectional microstructure and fracture micro-structural features under the different pulsed current sintering processes is studied. Experimental results show that the shear strength of the sandwich structure increase as the current increase, and the shear strength reach the highest value, i.e. 46.3 MPa, when the current is 0.8 kA, also the pulse electric current sinter nano copper paste and connect nanometer copper particles and nickel as well as copper substrates in a short time （less than 200 ms） to obtain a high density and high performance joint structure. Mechanism of pulse current sintering nano copper paste is proposed by analyzing the nano-copper solder paste microstructural features after the pulse current sintering.