Significant enhancement of comprehensive properties of SnBi solder through the addition of Cu@Ag core-shell particles

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 881; p. 145392
• Main Authors: Li, S.Q., Li, Q.H., Cao, H.J., Zheng, X.Z., Zhang, Z.H.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 10.08.2023
• Subjects: Electrical conductivity; Fracture; Microstructure; SnBi alloys; Tensile properties; Thermal conductivity; SnBi alloys; Thermal conductivity; Fracture; Electrical conductivity; Microstructure; Tensile properties
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2023.145392

As a critical low-temperature lead-free solder, SnBi eutectic solder was known for its abundant lamellar structures of Bi-rich phase, which often resulted in problems such as brittleness, low electrical conductivity, and low thermal conductivity. In this study, a method was introduced to enhance the comprehensive properties of SnBi solder by adding Cu@Ag core-shell particles. Our results revealed that the modified SnBi solder exhibited significant refinement in both grain size and intragranular eutectic structures, resulting in a shift from the original brittle fracture mode to a mixed brittle and tough mode and a consequent increase in tensile strength by 21%. Moreover, the modified solder demonstrated a significant 59% increase in electrical conductivity by forming interconnected highspeed channels for electron migration. In addition, the addition of Cu@Ag core-shell particles to SnBi solder resulted in remarkable contributions of both electrons and phonons to thermal conductivity, with its value of 41.33 W m−1 K−1. Our research addressed partial property deficiencies of SnBi solder, which could be valuable in expanding its application in low temperature electronic packaging. [Display omitted] •Cu@Ag core-shell particles of >15 wt% are successfully incorporated into SnBi solder.•Intragranular and intergranular refinement occur simultaneously in modified SnBi solder.•Dissolution and phase transformation of Ag shells contribute to improved solder strength.•Thermal conductivity of modified solder was significantly enhanced by electrons and phonons.