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This study aims to investigate the effect of a small amount of TiO₂ NPs addition on the microstructure, thermal, mechanical and electrical properties of environmentally friendly eutectic (SAC355)_100-x(TiO₂)_x (x = 0.1, 0.3, 0.5, 0.7 and 1 wt.%) solder alloys.

Mechanical, thermal and electrical properties and microstructure conditions are taken into major consideration in any study of materials containing nanoparticles. Dynamic resonance technique, X-ray diffraction and scanning electron microscopy were carried out to study stiffness, identification of the phases and the morphology features of the solder. Structure and microstructure analysis indicated that the presence of rhombohedral β–Sn phase in addition to orthorhombic intermetallic compound (IMC) Ag₃Sn and Cu₃Sn phase dispersed in Sn matrix. In addition, the results showed that TiO₂ NPs addition at a small trace amount into SAC355 system reduces and improves the particle size of both rhombohedral β–Sn and orthorhombic IMC Ag₃Sn and Cu₃Sn. The interstitial dispersion of TiO₂ NPs at grain boundaries resulted in Ag₃Sn being more uniform needle-like, which is distributed in the β–Sn matrix. The fine and uniform microstructure leads to improvement of mechanical strength.

Some important conclusions are summarized as follows: microstructure investigations revealed that the addition of TiO₂ NPs particles to eutectic SAC355 inhibited in reducing and refines the crystallite size as well as the Ag₃Sn IMC, which reinforced the strength of plain solder alloy. The mechanical properties values such as Young’s modulus and Vickers microhardness of SAC355 solder alloy can be significantly improved by adding a trace amount of TiO₂ NPs compared with plain solder because of the existence of appropriate volume fraction of Ag₃Sn IMC. The results show that the best creep resistance is obtained when the addition of 0.3 wt.% of TiO₂ NPs is compared to plain solder. TiO₂ NPs addition could increase the melting temperature, compared with plain solder. All results showed that TiO₂ NPs addition is an effective method to enhance new solder joints.

New solder alloys.

Development of TiO₂ NPs-doped eutectic SAC355 lead-free solder for electronic packaging.

This paper aims to summarise the effects of ZnO nanoparticles (0.1, 0.3, 0.5, 0.7 and 1.0 Wt.%) on the structure, mechanical, electrical and thermal stability of Sn–3.5Ag–0.5Cu (SAC355) solder alloys for high-performance applications.

The phase identification and morphology of the solders were studied using X-ray diffraction and scanning electron microscopy. Thermal parameters were investigated using differential scanning calorimetry. The elastic parameters such as Young's modulus (E) and internal friction (Q⁻¹) were investigated using the dynamic resonance technique, whereas the Vickers hardness (Hv) and creep indentation (n) were examined using a Vickers microhardness tester.

Microstructural analysis revealed that ZnO nanoparticles (NPs) were distributed uniformly throughout the Sn matrix. Furthermore, addition of 0.1, 0.3 and 0.7 Wt.% of ZnO NPs to the eutectic (SAC355) prevented crystallite size reduction, which increased the strength of the solder alloy. Mechanical parameters such as Young's modulus improved significantly at 0.1, 0.3 and 0.7 Wt.% ZnO NP contents compared to the ZnO-free alloy. This variation can be understood by considering the plastic deformation. The Vickers hardness value (Hv) increased to its maximum as the ZnO NP content increased to 0.5. A stress exponent value (n) of approximately two in most composite solder alloys suggested that grain boundary sliding was the dominant mechanism in this system. The electrical resistance (ρ) increased its maximum value at 0.5 Wt.% ZnO NPs content. The addition of ZnO NPs to plain (SAC355) solder alloys increased the melting temperature (T_m) by a few degrees.

Development of eutectic (SAC355) lead-free solder doped with ZnO NPs use for electronic packaging.