Ultrasonic welding uses a piezo crystal to generate high-frequency vibrations in the kilohertz range, which cause friction between the joining partners. This results in heating and melting of the joint and therefore creates the welded interconnection.

The most important parameters for this process are the ultrasonic energy (frequency and amplitude), the contact pressure and the welding time.

Ultrasonic welding is used for wire bonding and for connecting terminals to power modules.