Analysis of Ultrasonic Welding Technology of Aluminum Wire Copper Terminals

Previously, we mentioned that aluminum wires with large wire diameters have been used in automobiles, and they are still achieved by welding aluminum wires with copper terminals. So how to judge the weldability of aluminum wires and copper terminals?

1. Ensure good electrical performance of the welded part and ensure that the selected aluminum wire specification is equivalent to that of copper wire

The standard for copper conductors currently used in the industry is ISO6722–1 and the standard for aluminum conductors is ISO 6722–2. The equivalent substitution of aluminum wire must consider the characteristics of conductivity, current carrying capacity, derating curve and other characteristics similar to that of the replaced copper wire, so as to replace the conductor material and maintain the original circuit protection strategy.

2. Molecular movement between aluminum wires through ultrasonic welding

Ultrasonic welding uses high-frequency vibration waves to transmit to the surfaces of two objects to be welded, and under the condition of applying pressure, the surfaces of the two objects rub against each other, thus forming a fusion between molecular layers.

3. Ensure good mechanical properties of the welded part

Cable assemblies are subject to the risk of being pulled by external forces during use, especially for battery wires with large cross-sections, which tend to act directly on a single cable. For example, in the process of assembling battery wires, when it is inconvenient to install, the operator will pull the wires to generate a straight pull force in the direction of the wires, or apply a tearing force perpendicular to the welded surface of the wires. Therefore, adequate protection measures need to be considered when designing the terminal structure to resist straight pull and tear forces.

4. Ensure good resistance to electrochemical corrosion of welded parts

In order to prevent galvanic corrosion of copper terminals and aluminum conductors, it is important to isolate the connection from the humid or salty environment.

5. Ensure good manufacturability of the welded part

Ultrasonic welding is a high-speed reciprocating relative motion of two material surfaces under a certain pressure and frequency, and the two surfaces are melted at high temperatures through frictional movement, and the fusion of molecular layers is formed. Usually, the terminals are fixed to the welding equipment, and the wires are reciprocating at high frequency relative to the fixed terminals. Therefore, the terminals need to have a reliable structure to be fixed.