Effect of ultrasonic conditions on microstructural and mechanical of Sn58Bi and Sn58Bi solder joints with 0.6 % Si3N4 nanoparticles

This study used ultrasonic time as a variable to test Sn58Bi and Sn58Bi solder joints with 0.6 % Si₃N₄ nanoparticles. Ultrasound was applied to the solder joints for 0, 5, 10, and 15 s to observe how the microstructural and mechanical properties changed in the solder joints. It was found that the microstructure of the solder joint became more uniform with increasing ultrasonic time, and the thickness of the IMC increased after the application of ultrasound. Compared with Sn58Bi, the IMC of Sn58Bi-0.6Si₃N₄ was thicker. The IMC became more uniform when the ultrasonic time reached 15 s. In the absence of ultrasonic treatment, the solder still contained large particles, but with the increase in ultrasonic time, the grains became smaller. The shear strength increased with increasing ultrasonic time, reaching a maximum at 15 s of ultrasonic treatment. Compared to Sn58Bi, Sn58Bi-0.6Si₃N₄ had smaller particles and higher shear strength in its solder joints for the same ultrasonic time. The maximum shear strength reached 58.50 MPa at 15 s of ultrasonic time.