Ramli Mohd Izrul Izwan, Salleh Mohd Arif Anuar Mohd, Sandu Andrei Victor, Amli Siti Farahnabilah Muhd, Said Rita Mohd, Saud Norainiza, Abdullah Mohd Mustafa Al Bakri, Vizureanu Petrica, Rylski Adam, Chaiprapa Jitrin, Nabialek Marcin
Center of Excellence Geopolymer & Green Technology (CEGeoGTech), Universiti Malaysia Perlis (UniMAP), Jalan Kangar-Arau 02600, Perlis, Malaysia.
Faculty of Chemical Engineering Technology, Universiti Malaysia Perlis (UniMAP), Jalan Kangar-Arau 02600, Perlis, Malaysia.
Materials (Basel). 2021 Sep 7;14(18):5134. doi: 10.3390/ma14185134.
This manuscript reports the isothermal annealing effect on the mechanical and microstructure characteristics of Sn-0.7Cu-1.5Bi solder joints. A detailed microstructure observation was carried out, including measuring the activation energy of the intermetallic compound (IMC) layer of the solder joints. Additionally, the synchrotron µX-ray fluorescence (XRF) method was adopted to precisely explore the elemental distribution in the joints. Results indicated that the CuSn and Cu3Sn intermetallic layers thickness at the solder/Cu interface rises with annealing time at a rate of 0.042 µm/h for Sn-0.7Cu and 0.037 µm/h for Sn-0.7Cu-1.5Bi. The IMC growth's activation energy during annealing is 48.96 kJ mol-1 for Sn-0.7Cu, while adding Bi into Sn-0.7Cu solder increased the activation energy to 55.76 kJ mol. The µ-XRF shows a lower Cu concentration level in Sn-0.7Cu-1.5Bi, where the Bi element was well dispersed in the β-Sn area as a result of the solid solution mechanism. The shape of the IMC layer also reconstructs from a scallop shape to a planar shape after the annealing process. The Sn-0.7Cu hardness and shear strength increased significantly with 1.5 wt.% Bi addition in reflowed and after isothermal annealing conditions.
本手稿报道了等温退火对Sn-0.7Cu-1.5Bi焊点力学和微观结构特性的影响。进行了详细的微观结构观察，包括测量焊点金属间化合物（IMC）层的激活能。此外，采用同步加速器微X射线荧光（XRF）方法精确探究焊点中的元素分布。结果表明，在焊料/Cu界面处，Sn-0.7Cu的CuSn和Cu3Sn金属间化合物层厚度随退火时间以0.042 µm/h的速率增加，而Sn-0.7Cu-1.5Bi的增加速率为0.037 µm/h。Sn-0.7Cu在退火过程中IMC生长的激活能为48.96 kJ mol-1，而在Sn-0.7Cu焊料中添加Bi后，激活能增加到55.76 kJ mol。µ-XRF显示Sn-0.7Cu-1.5Bi中的Cu浓度水平较低，由于固溶机制，Bi元素在β-Sn区域中分布良好。退火后，IMC层的形状也从扇贝形重构为平面形。在回流和等温退火条件下，添加1.5 wt.% Bi后，Sn-0.7Cu的硬度和剪切强度显著增加。
