Cui Jianguo, Zhang Keke, Zhao Di, Pan Yibo
School of Materials Science and Engineering, Henan University of Science and Technology, Luoyang, 471023, China.
Provincial Ministerial Co-construction of Collaborative Innovation Center for Non-ferrous Metal New Materials and Advanced Processing Technology, Luoyang, 471023, China.
Sci Rep. 2021 Mar 18;11(1):6297. doi: 10.1038/s41598-021-85685-6.
Through ultrasonic wave assisted Sn2.5Ag0.7Cu0.1RExNi/Cu (x = 0, 0.05, 0.1) soldering test and - 40 to 125 °C thermal shock test, the microstructure and shear properties of Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints under thermal cycling were studied by the SEM, EDS and XRD. The results show that the Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints with high quality and high reliability can be obtained by ultrasonic assistance. When the ultrasonic vibration power is 88 W, the ultrasonic-assisted Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu solder joints exhibits the optimized performance. During the thermal cycling process, the shear strength of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints had a linear relationship with the thickness of interfacial intermetallic compound (IMC). Under the thermal cycling, the interfacial IMC layer of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints consisted of (Cu,Ni)Sn and CuSn. The thickness of interfacial IMC of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints was linearly related to the square root of equivalent time. The growth of interfacial IMC of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints had an incubation period, and the growth of IMC was slow within 300 cycles. And after 300 cycles, the IMC grew rapidly, the granular IMC began to merge, and the thickness and roughness of IMC increased obviously, which led to a sharp decrease in the shear strength of the solder joints. The 0.05 wt% Ni could inhibit the excessive growth of IMC, improve the shear strength of solder joints and improve the reliability of solder joints. The fracture mechanism of ultrasonic-assisted Sn2.5Ag0.7Cu0.1RExNi/Cu solder joints changed from the ductile-brittle mixed fracture in the solder/IMC transition zone to the brittle fracture in the interfacial IMC.
通过超声波辅助的Sn2.5Ag0.7Cu0.1RExNi/Cu（x = 0、0.05、0.1）焊接试验以及-40至125°C的热冲击试验，利用扫描电子显微镜（SEM）、能谱仪（EDS）和X射线衍射仪（XRD）研究了热循环下Sn2.5Ag0.7Cu0.1RExNi/Cu焊点的微观结构和剪切性能。结果表明，通过超声波辅助可获得高质量、高可靠性的Sn2.5Ag0.7Cu0.1RExNi/Cu焊点。当超声振动功率为88 W时，超声波辅助的Sn2.5Ag0.7Cu0.1RE0.05Ni/Cu焊点表现出最佳性能。在热循环过程中，超声波辅助的Sn2.5Ag0.7Cu0.1RExNi/Cu焊点的剪切强度与界面金属间化合物（IMC）的厚度呈线性关系。在热循环下，超声波辅助的Sn2.5Ag0.7Cu0.1RExNi/Cu焊点的界面IMC层由（Cu，Ni）Sn和CuSn组成。超声波辅助的Sn2.5Ag0.7Cu0.1RExNi/Cu焊点界面IMC的厚度与等效时间的平方根呈线性关系。超声波辅助的Sn2.5Ag0.7Cu0.1RExNi/Cu焊点界面IMC的生长有一个孕育期，在300次循环内IMC生长缓慢。300次循环后，IMC迅速生长，颗粒状IMC开始合并，IMC的厚度和粗糙度明显增加，导致焊点的剪切强度急剧下降。0.05 wt%的Ni可抑制IMC的过度生长，提高焊点的剪切强度并改善焊点的可靠性。超声波辅助的Sn2.5Ag0.7Cu0.1RExNi/Cu焊点的断裂机制从焊料/IMC过渡区的韧性-脆性混合断裂转变为界面IMC中的脆性断裂。
