Investigation of ultrasonic bonding interface based on Ni micro-nano cones array

Ultrasonic bonding based on Ni micro-nano cones array (MCA) was developed in this study. Interfacial morphologies of bonding joints were investigated. The deformation of nanocones demonstrated the complexity of initial indentation process. Analysis of morphology evolution under different bonding pressure revealed that interfacial voids shrinkage faster as pressure increase. The time dependent morphology evolution was varied under different bonding pressure. The critical bonding pressure was defined as 7MPa. Under the pressure lower than 7MPa, longer bonding time did not enhance the joint but extended the voids to cracks. As bonding pressure raised to 7MPa or larger, bonding time strengthened the joint and void shrinkage process was observed. The Ni MCA morphology evolution from cone-like to ladder-like and finally plane-like was observed in the interfaces.