Microstructure and shear properties evolution of Mn-doped SAC solder joint under isothermal aging

• Published in: Journal of iron and steel research, international Vol. 30; no. 8; pp. 1650 - 1660
• Main Authors: Li, Cheng-ming, Chen, Shu-jin, Cai, Shan-shan, Peng, Ju-bo, Wang, Xiao-jing, Wang, Ying-wu
• Format: Journal Article
• Language: English
• Published: Singapore Springer Nature Singapore 01.08.2023
• Subjects: Applied and Technical Physics; Engineering; Machines; Manufacturing; Materials Engineering; Materials Science; Metallic Materials; Original Paper; Physical Chemistry; Processes; Shear mechanical behavior; Isothermal aging; Interfacial intermetallic compound; SAC305 solder; Mn doping
• ISSN: 1006-706X; 2210-3988
• DOI: 10.1007/s42243-023-01027-y

The effects of Mn addition (0.005, 0.01, 0.03, 0.05, and 0.07 wt.%) on microstructure, shear mechanical behavior, and interfacial thermal stabilities of SAC305 joints were investigated under isothermal aging temperatures of 170 °C with different aging time (0, 250, 500, and 750 h). It is found that Mn addition can increase fracture energy of joints without decreasing the shear strength. And the microstructures have transformed from the eutectic net-like structure in SAC305 solder joints into the structures based on β-Sn matrix with intermetallic compounds (IMCs) distributed. By doping 0.07 wt.% Mn, the Cu 6 Sn 5 growth along the SAC305/Cu interface during thermal aging can be inhibited to some extent. During isothermal aging at 170 °C, the maximum shear force of solder joint decreases continuously with aging time increasing, while the fracture energy rises first and then decreases, reaching the maximum at 500 h compared by that with the microstructure homogenization. Cu 3 Sn growth between Cu 6 Sn 5 /Cu interface has been retarded most at the aging time of 250 h with 0.07 wt.% Mn-doped joints. With the aging time prolonging, the inhibition effect of Mn on Cu 3 Sn IMC layer becomes worse. The strengthening effect of Mn can be explained by precipitation strengthening, and its mechanical behavior can be predicted by particle strengthening model proposed by Orowan.