The lug welding on the lithium battery pack of the popular electric vehicles, as well as the welding of the wire harness and wire harness inside the vehicle, and the welding of the wire harness and terminal. This type of welding material is usually copper or aluminum with high conductivity. After ultrasonic welding, the product has low resistivity, good conductivity, and high welding strength. At the same time, ultrasonic metal welding has small heat affected area, no flux, no spark, and no high brightness. It is a very safe welding process.