Our study investigates the mechanism and effects of incorporating different ZrO2 nano-particles into SAC0307 solder alloys.
ZrO2 nano-powder and nano-fibers in 0.25 and 0.5 wt% were added to the SAC0307 alloy to prepare composite solder joints by surface mount technology. The ZrO2 had the following dimensions: nano-powder (np) with primary particle sizes of less than 100 nm, and nano-fibers (nf) with diameters of 200–800 nm ± 100 nm and lengths of 2–10 μm (polycrystalline).
The solder joints were shear tested before and after a 4000 h long 85 °C/85% RH corrosive reliability test. The solder joints were observed after each 1000 h of the test by a Thermo Scientific Quatro scanning electron microscope (SEM). FIB cuts were prepared and analyzed on the samples by a Thermo Scientific Scios 2 fo-cused ion beam (FIB) to study the microstructure of the solder joints. Elemental compo-sitions were measured by Bruker energy dispersive X-ray spectroscopy (EDS). The potential interaction between Sn and ZrO2 was investigated using density functional theory (DFT) calculations and simulations.
The incorporation of ZrO2 nano-particles enhanced the initial shear force of the solder joint, but they decreased the corrosion resistance in the case of 0.5 wt%. SEM, EDS, and FIB analysis revealed intensive growth of SnO2 on the solder joint surfaces, leading to the formation of Sn whiskers. Density functional theory (DFT) simulations showed that, despite Sn being able to bond to the surface of ZrO2, the binding energy was weak, and the whole system was therefore unstable. It was also found that ZrO2 nano-particles refined the microstructure of the solder joints. Decreased β-Sn grain size and more dispersed intermetallic compounds were observed. The microstructural refinement caused mechanical improvement of the ZrO2 composite solder joints by dispersion strengthening but could also decrease their corrosion resistance. While ZrO2 nano-particles im-proved the solder joint mechanical properties, their use is recommended only in non-corrosive environments, such as microelectronics for space applications.
The dataset consists:
· the published figures in the article in high resolution
· supplementary SEM micrographs of the cross-sectioned solder joints
· supplementary optical micrographs of the cross-sectioned solder joints
(2025-09-24)
