Junction for copper terminal and aluminium conductor and ultrasonic welding method thereof

Abstract

The invention belongs to the field of a wiring hardness and specifically relates to a junction for a copper terminal and an aluminium conductor and an ultrasonic welding method thereof. In order to solve the problem that in the prior art, the electrochemical corrosion exists in the welding between the copper terminal and the aluminium conductor and the mechanical property of a welding junction is low, according to the junction and the method, a spacing metal layer is added between the copper terminal and the aluminium conductor. The spacing metal layer is fixed at a welding end of a base material in modes such as electroplating, pressure welding, electric arc spray welding or electromagnetic welding, and then the three parts: the spacing metal layer, the copper terminal and the aluminium conductor are welded together. The ultrasonic welding method provided by the invention is applicable to the welding of the copper terminal and the aluminium conductor and also applicable to the welding of various junctions. The electrochemical corrosion resulting from the potential difference of copper and an aluminium electrode can be effectively reduced. The mechanical property of the junction is improved.

Description

technical field [0001] The invention belongs to the field of wire harnesses, in particular to a joint for connecting copper terminals and aluminum wires in the wire harness and an ultrasonic welding method thereof. Background technique [0002] Copper has good electrical conductivity, thermal conductivity, and plasticity and is widely used. However, copper resources are in short supply and copper costs are high. For this reason, people began to look for copper substitutes to reduce costs. The price of aluminum is relatively low, and it also has excellent electrical conductivity, thermal conductivity and plastic workability. Therefore, replacing copper with aluminum is the main trend of development at present. However, some properties of aluminum are still not as good as copper, and many components still cannot be fully used. Aluminum replaces copper, so there is joint welding between aluminum components and copper components. For example, wires made of aluminum-based mate...

AI Technical Summary

Problems solved by technology

[0003] For the connection conduction of aluminum and copper, there are two technical problems that have not been resolved: 1) aluminum is an active metal, and the dense oxide film with a thickness of about 50 angstroms (1 angstrom=0.1 nanometer) is formed immediately on the surface of aluminum in dry air, making Aluminum will not oxidize further, but it also greatly reduces the conductivity of the aluminum wire

2) Copper and aluminum are different elements. The metal inertness of copper is greater than that of aluminum. The electrode potential difference between copper and aluminum is 1.9997V. After the two metals are connected and energized, an electrochemical reaction will occur, causing the aluminum wire to be gradually oxidized , reduce the mechanical strength and electrical conductivity of the aluminum wire

Significant problems with ultrasonic brazing when joining copper terminals and aluminum wires to prepare joints precludes its use in the industrial preparation of copper terminals and aluminum wire joints

Specifically, the solder of ultrasonic brazing is not easy to fill the weld seam, and it is easy to form unfilled irregular gaps between the copper terminal and the aluminum wire

However, this kind of gap can only be tested by all destructive tests, which cannot guarantee that each joint can meet the requirements of electrical and mechanical properties stably.

Therefore, the method of preparing copper terminals and aluminum wire joints by ultrasonic brazing cannot be applied in mass industrial production.

[0008] In summary, in the prior art, there is no welding method that can meet the mechanical and electrical performance requirements of various shapes of copper terminals and aluminum wire joints used in wire harnesses.

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