An ultrasonic weld is a weld accomplished through high-frequency ultrasonic acoustic vibrations. Usually ultrasonic welds are done to weld plastics and joining dissimilar materials. This type of welding is used to build assemblies that are too small, too complex, or too delicate for more common welding techniques. In ultrasonic welding, there are no connective bolts, nails, soldering materials, or adhesives necessary to bind the materials together.