Soldering method using longitudinal ultrasonic

An efficient ultrasonic soldering method of inserting the metal bumps into the solder is investigated in this work for electronic packaging. The effects of the process parameters such as the ultrasonic frequency, amplitude, dimensions of the metal bump and solder are analyzed through the viscoelastic modeling. The ultrasonic soldering was conducted using the Cu and Au bumps, and the acceptable bonding condition was determined from the tensile strength. Localized heating of the solder was achieved and the stirring action due to the ultrasonic influences the bond strength and microstructure of the eutectic solder. Since higher temperature is obtained with smaller solder, the proposed ultrasonic soldering method appears to be applicable to the high-density electronic packaging.