Study on Hardness and Shear Strength with Microstructure Properties of Sn52Bi/Cu + 1% Al₂O₃ Nanoparticles

<jats:title>Abstract</jats:title>
<jats:p>The Sn-58Bi (SB) lead-free solder was added with 1% nanoparticles (NP) of aluminium oxide (Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>) to investigate the shear strength based on microstructure and joint properties. The microstructures of the SB added with 1% Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> NP containing Bi precipitation and β-Sn grains. The spacing between the lamellar structures of a SB solder alloy was narrower. Proper arrangement of the microstructure of β-Sn, Bi and with the presence of Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> as discrete particles (dispersion strengthening) contributes to the increase on the shear strength and hardness value. The shear strength of the SB added with 1% Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> NP solder joint was enhanced by 50% compared to the bare SB solder joint while there was a 33% increase in the microhardness as well. The shear test was conducted based on ASTM D1002 specification of single lap joint method. The presence of Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> NP along the interface (Hall-Petch effect) contributes to the improvement in the shear strength by reducing the thickness of the IMC layer and retarding the growth of the Cu<jats:sub>6</jats:sub>Sn<jats:sub>5</jats:sub> IMC layer. This study provides evident results for the enhancement of the mechanical properties of the 1% Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> NP added SB solder.</jats:p>