Cavitation at filler metal/substrate interface during ultrasonic-assisted soldering. Part II: Cavitation erosion effect.

Using pure Sn as filler metal, this study investigated cavitation erosion effects during ultrasonic-assisted soldering. The physical process and mechanism of cavitation erosion were revealed. Superior erosion effects were observed under long ultrasonic times, small channel widths, and high ultrasonic powers. Different vibration intensities were obtained inside filler pool. Region I, which was located far from the sonotrode, exhibited a stronger vibration intensity and better erosion effect than those of the other regions. The erosion incubation stage was shorted than 0.5 s at the channel width of 0.2 mm. Complete oxide layer removal was obtained at an ultrasonic time of 2 s under this condition. The violent cavitation stage was shorter than the erosion incubation stage, and the removal of the oxide layer mainly depended on the stable cavitation stage.