Ultra-rapid and low-temperature soldering of hypereutectic Al-Si alloys by ultrasonic-assisted soldering with In interlayer in air for electronic application

Abstract

Hypereutectic Al-Si alloys were soldered by an ultrasonic-assisted soldering with In interlayer for only 0.1 s at 160 °C in air. The introduction of ultrasonic vibration into the soldering process promoted the formation of the liquid phase by its acoustic softening effect, ultrasonic cavitation effect and acoustic streaming. The effects of ultrasonic vibration on the formation of Al-In liquid phase were also discussed. The microstructure evolution of solder joint and the migration of Si particles were influenced by ultrasonic vibration. The complex solder joint obtained by the ultrasonic-assisted approach consisted of Si particles and Al-In solid solution. Si particles could be regarded as tracers and reinforced phase. The influence of ultrasonic vibration time, pressure and temperature on the microstructure of the solder joint was investigated. The effect of ultrasonic vibration on shear strength of the joints was also discussed. Image-Pro-Plus Analysis was used to estimate content of Si particles in solder joint. The shear strength of the joints was obtained, when the suitable ultrasonic vibration time, temperature and pressure were chosen.