Effect of fullerene-C60&C70 on the microstructure and properties of 96.5Sn-3Ag-0.5Cu solder

Abstract

In this study, fullerene nanoparticles (FNSs, a mixture of approximately 80%C60, 20%C70), by varying their weight fractions (0.05, 0.1 and 0.2wt. %) were successfully added into the SAC305 lead free solder to fabricate composite solders through the powder metallurgy processing route. As well as the retained ratios of fullerene reinforcements in the solder joints were firstly tested, the composite solders were also characterized in terms of their microstructure, melting points, electrical conductivity, wettability and mechanical properties.The retained ratio of FNSs reinforcements in the solder joints shows a considerable decrease with the increase of reflow cycles. After FNSs addition to the solder alloy, the Sn rich phase and IMC phases (Cu 6 Sn 5 and Ag 3 Sn) with a finer microstructure were observed in the solder matrix. With the increasing addition of fullerene, the composite solders showed an improvement in their wetting property but an insignificant change in their melting points and conductivity. The mechanical results indicated that the addition of 0.2wt. % fullerene can lead to 12.1% and 28.2% improvement in micro-hardness and shear strength respectively, when compared with that of the unreinforced solders. Furthermore, the FNSs doped composites exhibited better mechanical performance throughout the 360h aging period.These results obtained from this study proved that the addition of fullerene can improve not only the mechanical properties of the solder alloy, but also the wettability without any notable effect on the melting point and conductivity. Thus, these fullerene doped composite solders can be further developed as a potential material for microelectronics assembly and packaging industry.

Enhancement of Microstructural and Physical Properties of Sn-0.7Cu Lead-Free Solder with the Addition of SiC Particles

“…The refined microstructure also contributed to the enhancement of microhardness value in the composite solder. Besides, Chen et al, [12] also found the addition of fullerene nanoparticles (FNSs) into the SAC305 were able to refine microstructure of the composite solder. The microstructure of SnCu composite lead-free solders was observed by using SEM backscattered image.…”

“…It believed the decreasing size of β-Sn region which has increased the microhardness of composite solder due to the classical dispersion strengthening theory. From that theory, the foreign particles that located in the solder alloy matrix and grain boundaries are likely to change the solder alloy's deformation characteristics by retarding dislocation movement as well as impeding grain-boundary sliding in solder matrix, resulting in enhancement in microhardness [12]. The additional of SiC particles influence the growth and size of the β-Sn region in SnCu-SiC composite lead-free solder.…”

Retained ratio of reinforcement in SAC305 composite solder joints: effect of reinforcement type, processing and reflow cycle

“…In the latter, a solder powder and reinforcement are blended by ball milling before compacting, sintering and subsequent extrusion or rolling. However, no matter what method is used, most of the reinforcement added is often excluded outside of the solder joints in the soldering process (Liu et al, 2008;Chen et al, 2015). In such cases, the amount of reinforcement retained in the final solder joints is quite different from the initial one, leading to a reduction in the enhancing effect due to limited doping with the reinforcement.…”