Ceramic nano-particles are frequently used as reinforcements in SAC alloys to improve their mechanical properties; however, the nano-particle dispersion and incorporation mechanisms are not well known.
We fabricated composite SAC alloys from 99Sn0.3Ag0.7Cu (SAC0307) alloy (Alpha) with TiO2 and SiC NPs (powder and fibers) in 0.5wt%. We used four types of NPs during the investigations. There were two types of TiO2 rutile nano-powders: TiO2-p1 with 21nm primary particle size, and TiO2-p2 with 200nm primary particle size; and two types of SiC NPs, SiC nano-powder, SiC-p < 100nm primary particle size, and SiC nano-fiber, SiC-f, with D<2.5μm diameter and a L/D≥20 length/diameter ratio.
We observed the solder joints’ microstructure by an FEI Inspect S50 Scanning Electron Microscopy (SEM) on the cross-sections. We measured the elemental compositions by energy dispersive x-ray spectroscopy (EDS). We performed secondary ion mass spectrometry (SIMS) measurements on the cross-sections using a CAMECA IMS SC Ultra instrument operating in an ultra-high vacuum around 4x10-10 mbar) to determine the nano-particle distribution along the solder joints' vertical cross-section. DFT calculations were done to investigate the possible interaction between the different nano-particles and the Sn atoms.
SIMS results showed that the distribution of the nano-particles is inhomogeneous in the solder bulk; furthermore, the density characteristics highly depend on the size and shape of the nano-particles. DFT calculations proved that the non-soluble TiO2 and SiC could form chemical bonds with the Sn during the soldering, which might further explain their positive effect on the physical properties of composite SAC alloys.
The dataset consists:
· the published figures in the article in high resolution
· supplementary SEM micrographs of the cross-sectioned solder joints
· the original data of the SIMS measurements (in Origin format). Free viewer for Origin files is available: https://www.originlab.com/viewer/
(2025-09-24)
