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Investigation of Bi Content Effects on Sn-0.7Cu Microstructure and Properties Under Different Processing Conditions.

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Bibliographic Details
Title:	Investigation of Bi Content Effects on Sn-0.7Cu Microstructure and Properties Under Different Processing Conditions.
Authors:	Yu, Zhuhuan¹ (AUTHOR) yzh0709qyy@xust.edu.cn, Wang, Ziyan¹ (AUTHOR), Yang, Xiong¹ (AUTHOR), Lv, Haiyan¹ (AUTHOR), Qiang, Junfeng¹ (AUTHOR), Yang, Zi¹ (AUTHOR), Shangguan, Xirui¹ (AUTHOR), Ma, Tianxiao¹ (AUTHOR)
Source:	JOM: The Journal of The Minerals, Metals & Materials Society (TMS). Jun2026, Vol. 78 Issue 6, p5622-5630. 9p.
Subjects:	Lead-free solder, Directional solidification, Electronic packaging, Mechanical behavior of materials, Melting, Microstructure
Abstract:	To address the demand for lead-free solders in electronic packaging and overcome Sn-Cu alloys' high melting point and insufficient mechanical properties, this study prepared Sn-0.7Cu-0.1Te-xBi solders (x = 0,2,3,4 wt%) via Te-Bi composite microalloying combined with resistance melting and directional solidification, investigating their microstructure, post-welding interfacial features, mechanical properties, and conductivity. Results showed Bi refined the β-Sn phase and modified Cu6Sn5 morphology. Directional solidification suppressed Bi segregation to realize a uniform component solid solution, while resistance melting easily caused Bi precipitation at grain boundaries. For directional solidification, 3 wt% Bi was optimal—the solder had 65 MPa tensile strength and good ductility, with a continuous, defect-free scallop-like intermetallic compound layer after welding. For resistance melting, 4 wt% Bi obtained the best hardness of 33.3 HV and tensile strength of 82.03 MPa, but ductility degraded sharply with only 8.86% elongation. Regarding conductivity, directional solidification solder resistivity rose steadily with Bi content, while resistance melting solder resistivity first increased then decreased. This study clarifies the solder's optimal composition and process, supporting high-performance Sn-Cu-based lead-free solder development. [ABSTRACT FROM AUTHOR]
	Copyright of JOM: The Journal of The Minerals, Metals & Materials Society (TMS) is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database:	Engineering Source

Description
Abstract:	To address the demand for lead-free solders in electronic packaging and overcome Sn-Cu alloys' high melting point and insufficient mechanical properties, this study prepared Sn-0.7Cu-0.1Te-xBi solders (x = 0,2,3,4 wt%) via Te-Bi composite microalloying combined with resistance melting and directional solidification, investigating their microstructure, post-welding interfacial features, mechanical properties, and conductivity. Results showed Bi refined the β-Sn phase and modified Cu6Sn5 morphology. Directional solidification suppressed Bi segregation to realize a uniform component solid solution, while resistance melting easily caused Bi precipitation at grain boundaries. For directional solidification, 3 wt% Bi was optimal—the solder had 65 MPa tensile strength and good ductility, with a continuous, defect-free scallop-like intermetallic compound layer after welding. For resistance melting, 4 wt% Bi obtained the best hardness of 33.3 HV and tensile strength of 82.03 MPa, but ductility degraded sharply with only 8.86% elongation. Regarding conductivity, directional solidification solder resistivity rose steadily with Bi content, while resistance melting solder resistivity first increased then decreased. This study clarifies the solder's optimal composition and process, supporting high-performance Sn-Cu-based lead-free solder development. [ABSTRACT FROM AUTHOR]
ISSN:	10474838
DOI:	10.1007/s11837-026-08304-7