Structural, Thermal, and Electrical Behavior of Tin-aluminum Alloy Modified with Indium

Abstract

Lead-free solder alloys are crucial in the electronics production sector due to environmental and health concerns. While tin aluminum alloys are good alternatives, the addition of indium improves their properties. This study investigates the effect of indium addition on the structural, thermal, and electrical properties of tin aluminum alloys. Sn_95-xAl₅In_x alloys (where x = 5, 10, and 15 wt.%) were made, and examined using X-ray diffraction, scanning electron microscopy and differential  scanning calorimetry. The mechanical, electrical and thermal properties were measured. The addition of indium caused changes in the microstructure and the formation of intermetallic compounds. The Vickers hardness increased from 36.43 kg/mm² for Sn₉₅Al₅ alloys to 38.92 kg/mm² for Sn₈₀Al₅In₁₅ alloys, while the modulus of elasticity increased from 31.71 GPa to 37.92 GPa with increasing indium content. The melting temperature decreased by up to 130 °C, while mechanical strength and hardness varied with indium content. Electrical resistivity showed variations depending on indium concentration as well. This work is notable for investigating the change in electrical resistivity with varying indium content, highlighting the important role of indium in modifying these properties. The results demonstrate that tin-aluminum-indium alloys exhibit modified melting points and improved mechanical properties, suggesting their potential use in lead-free welding applications and improved welding efficiency.