Method for contact resistance determination of copper during fast temperature changes
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Method for contact resistance determination of copper during fast temperature changes Lukas Biele1,2,*
, Peter Schaaf1, and Florian Schmid2
1
Chair Materials for Electrical Engineering and Electronics, Institute of Materials Science and Engineering, Institute of Micro and Nanotechnology, MacroNano, TU Ilmenau, Gustav-Kirchhoff-Str. 5, 98693 Ilmenau, Germany 2 Corporate Sector Research and Advance Engineering, Robert Bosch GmbH, Post Box 30 02 40, 70442 Stuttgart, Germany
Received: 10 September 2020
ABSTRACT
Accepted: 21 October 2020
Contact resistance is crucial for temperature evolution at the fusion zone during resistance welding. In this paper, we introduce a new approach to determinate specific electrical contact resistance qcont;el for a constant contact pressure during dynamic temperature changes. We utilize total resistance curves from a specially designed experimental apparatus, implement them in a FEA-method and use this simulation method to separate material and contact resistance to calculate the specific contact resistance. The experimental setup is especially designed to achieve homogenous contact conditions during dynamic heating from real welding currents. We perform numerical and experimental validation of the developed determination method, including the usage of temperature measurements in the region of the fusion zone. Finally, we present pressureand temperature-dependent data for specific contact resistance of Cu-ETP R200 (CW004A, soft) up to temperatures of 400 C for two given contact pressures (64 MPa and 160 MPa) and a variation of contact surface properties. The data show a decrease in contact resistance with increasing temperature and pressure. Additionally, the properties of the surface show a strong influence on the contact resistance values.
Springer Science+Business
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Handling Editor: Kevin Jones.
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https://doi.org/10.1007/s10853-020-05490-w
J Mater Sci
GRAPHICAL ABSTRACT
Introduction Resistance welding (RW) is a widely used joining technology in the industry because of robustness and low costs of the process. In electrical applications, copper is the material of choice due to its low specific resistance resulting in low thermal losses. Typical applications are the connection of busbars with cables or pins with connectors. The property of the desirable low resistance of the joint results in a challenge with regard to the RW process of the components. Heat generation during the weld from Joule heating changes with local resistivity at the different regions of the assembly. Due to the low heat generation in the bulk material, additional heat generation from contact resistances at the contact surfaces is important for the process. Contact resistance (CR) is one of the crucial features of the weld and is a target in different studies performed. The focus of this work is the development of a method for the determination of specific contact resistance as a function of contact t
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