Effect of annealing on the microstructure and bonding interface properties of Ag–2Pd alloy wire

• The study developed an Ag–2Pd wire for high electrical conductivity and cost savings.
• Annealing at 275 °C is suitable for obtaining high-quality Ag–2Pd wire.
• The IMCs of the Ag–2Pd and Al system were mainly Ag3(Pd)Al and Ag2(Pd)Al.
• Annealing Ag–2Pd wire is a novel and efficient design.

This study investigated the mechanical and electrical properties of Ag–2Pd wire after thermal annealing. The thermal stability of the tested wire was examined by separately imposing static annealing at 275 °C, 325 °C and 375 °C in a vacuum environment. It was found that annealing the Ag–2Pd wire at 275 °C promoted the formation of a fully annealed structure with equiaxed grains. Annealing Ag–2Pd wire had a shorter heat affect zone (HAZ) length than those of conventional wire, and offered outstanding mechanical properties. A long-term electrical test found Ag3(Pd)Al and Ag2(Pd)Al compounds between the Ag–Pd ball and Al pad. These results confirmed the high-reliability properties of annealed Ag–2Pd wires for the wire bonding process.