Microstructure, mechanical, and thermal behaviors of SnBi/Cu solder joint enhanced by porous Cu

• Published in: Journal of materials science. Materials in electronics Vol. 31; no. 11; pp. 8258 - 8267
• Main Authors: Liu, Yang, Ren, Boqiao, Zhou, Min, Zeng, Xianghua, Sun, Fenglian
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.06.2020; Springer Nature B.V
• Subjects: Additives; Characterization and Evaluation of Materials; Chemistry and Materials Science; Copper; Grain size; Hardness; Heat conductivity; Heat transfer; Materials Science; Microstructure; Optical and Electronic Materials; Performance enhancement; Shear strength; Soldered joints; Soldering; Thermal conductivity; Tin
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-020-03361-3

Porous Cu sheets with the pores per inch (ppi) of 110 and 500 were used as additives to improve the performances of the Sn58Bi (SnBi) solder joint. The effects of porous Cu on the microstructure, interfacial IMC, hardness, shear behavior, and thermal conductivity of the solder were investigated in this study. Experimental results indicate that there are many Cu-surrounded areas in the SnBi@110-Cu solder bulk. The Bi-rich phase and β-Sn phase in those areas show refined grain size and high hardness. The density of porous Cu in SnBi@500-Cu is higher than that in SnBi@110-Cu, and the Cu distributes uniformly in the solder bulk. Porous Cu interacts with the molten SnBi during the soldering process, resulting in an increase of the Cu concentration in the solder matrix, and then the growth of the Cu 6 Sn 5 interfacial IMC is promoted. The addition of porous Cu has a positive effect on the improvement of the shear strength and thermal conductivity of the SnBi/Cu solder joint. In this study, the SnBi@500-Cu/Cu joint shows the highest shear strength and thermal conductivity with the average values of 83.51 MPa and 41.32 W/m K, respectively.