Effect of Ce and Cr Additions on the Physical and Mechanical Properties of Materials of Sn-9Zn Solder Alloy

<div>With rising environmental concerns, developing lead-free solders is crucial for sustainable electronics. Traditional lead-based solders, while effective, pose health and environmental risks, prompt a shift to safer alternatives that retain reliability. Sn-9Zn alloys, when alloyed with elements such as cerium (Ce) and chromium (Cr), show enhanced mechanical and thermal properties suited for modern electronics. This study examines the effects of Ce and Cr, and their combination in Sn-9Zn solder alloy, analyzing improvements in microstructure, thermal, wettability, and hardness properties. Microstructural analysis reveals that Ce and Cr additions refine the alloy’s structure, benefiting performance. Wettability testing shows that Sn-9Zn-0.05Ce achieves the lowest wetting angle, while Sn-9Zn-0.05Ce-0.1Cr displays a balanced angle between Sn-9Zn-0.05Ce and Sn-9Zn-0.1Cr. Differential scanning calorimetry (DSC) results indicate that Sn-9Zn-0.05Ce has the lowest melting temperature, while Sn-9Zn-0.1Cr has the highest, with Ce and Cr together reducing the melting temperature by 2.83°C from the peak in Sn-9Zn-0.1Cr. Apart from this, the Vickers microhardness test reveals the highest hardness in Sn-9Zn-0.05Ce-0.1Cr with 19.62 HV, underscoring the strengthening effects of Ce and Cr. The outcomes suggest Ce and Cr alloying as a promising approach to enhance the performance of lead-free solders in eco-friendly electronics.</div>