纳米Ni颗粒增强无铅Sn-Cu-Ag复合钎料搅拌辅助低温钎焊技术

Low-temperature soldering technology with stirring for nano-Ni particle-reinforced lead-free Sn-Cu-Ag composite solders

采用搅拌辅助低温(半固态区间)钎焊技术,制备低银无铅钎料和纳米复合钎料钎焊接头。结果表明:240℃时复合钎料的润湿时间较基体的润湿时间缩短了31%,润湿力较基体的提高了3.8%;机械搅拌在破碎树枝晶和加速元素扩散的同时,降低了液相的温度梯度和成分过冷,大大削弱了钎料基体中金属间化合物(IMC)Cu6Sn5的枝晶生长,促使针状Cu6Sn5破碎呈短棒状;在低银无铅钎料中加入纳米Ni颗粒,Ni与Cu6Sn5生成孔洞状化合物(Cux Ni1-x)6Sn5及低温搅拌形成的气孔成为界面原子的扩散通道。搅拌形成的紊流和热流传递加快了原子的溶解与扩散,加速了界面IMC的生长。

The soldering joints of low silver solder and nano-particle lead-free Sn-Cu-Ag composite solder were prepared by the technology of low-temperature soldering （at semi-solid state） with stirring, respectively. The results show that the wetting time of nano-particle composite solder is decreased by 31% at 240 ℃, and the wetting power is increased by 3.8% compared those of with the matrix. Mechanical mixing can break dendrites and accelerate the diffusion of elements, and also reduce the temperature gradient and the composition undercooling of the liquid, thus, greatly weaken the growth of IMC-Cu6Sn5 dendrite in solder matrix and making needle-shaped intermetallic compound （IMC） Cu6Sn5 break into short rod-like. After adding nano-Ni particles into the low silver solder, cavitary compounds of （CuxNil-x） 6 Sn5 generated by Ni with Cu6Sn5 and the porosities formed by stirring at low temperature are as the diffusion path of interface atoms. The turbulent flow and heat flow due to stirring accelerate the dissolution and diffusion of the atom, and speed up the growth of IMC.