外能辅助下Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu钎焊接头组织与性能

采用SEM、EDS、XRD等方法研究了超声、电场外能辅助下Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu钎焊接头的组织与性能。结果表明,借助于超声、超声-电场外能辅助能细化Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu钎焊接头钎缝组织并使共晶组织比例增加,界面区金属间化合物(IMC)平均厚度、粗糙度和界面IMC颗粒尺寸减小。超声和电场外能辅助下Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu钎焊接头强度与其界面IMC层粗糙度密切相关,超声的作用更为显著,在超声-电场外能辅助钎焊接头界面IMC层粗糙度降低中占主导作用,施加超声-电场外能辅助下钎焊接头剪切强度与传统钎焊相比提高24.1%;施加超声、超声-电场外能辅助使Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu钎焊接头断裂途径由钎缝和界面IMC层组成的界面过渡区向钎缝侧迁移,呈界面(Cu,Ni)_6Sn_5 IMC解理和钎缝解理+韧窝的脆-韧混合型断裂机制,使接头剪切断口塑性区比例增加,从而提高接头剪切强度。

Microstructure and properties of Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu solder joints obtained by external energy assisted soldering

Abstract: The Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu solder joints were fabricated by the ultrasionc wave (USW) and the electric field (E) assisted soldering technique. The microstructure and mechanical properties of solder joints were analyzed by the scanning electron microscope (SEM), the energy dispersive spectrometer (EDS) and the X-ray diffraction (XRD). The Results showed that the USW or the USW-E have great influence on the microstructure of the solder joints. The USW or the USW-E assisted soldering technique not only can refine microstructure of the Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu solder joints and promote the proportion of eutectic structure, but also can reduce the average thickness, the roughness and the grain size of interfacial IMC. The shear strength of the Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu soldering joints under the USW-E assisted soldering is closely related to the roughness of interfacial IMC layer. The USW played an important role in the decrease of the roughness of the interfacial IMC during the USW-E assited soldering. Compared with shear strength of the traditional soldering joints, a 24.1% increase of shear strength of the soldering joints was achieved with the USW-E assisted soldering. With applying the USW or the USW-E, the fracture path of the Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu soldering joints was transferred from the interfacial transitional region composed of soldering seam and interfacial IMC layer to the side of soldering seam. The fracture mechanism of the soldering joints obtained by the USW or the USW-E assisted soldering was brittle-ductile mixed fracture with the cleavage of interfacial (Cu, Ni)6Sn5 IMC and the cleavage-dimple of soldering seam, which increased the proportion of ductile fracture zone and the shear strength of soldering joints.