Copper-plated cold-rolled steel strip: Highly conductive and visually appealing
Copper-plated cold-rolled steel strip from Waelzholz is a composite material with an interesting combination of properties. Thanks to our in-house electroplating line at our production facility in São Paulo, Brazil, we have more than 30 years of experience in surface finishing through electrolysis. We discussed the advantages and unique properties of this material combination with our materials expert Thomas Frank.
Thanks to copper’s excellent electrical conductivity and attractive appearance, copper-plated cold-rolled steel strip is used primarily in electronics and electrical engineering, but also in decorative applications, such as eyelets and trouser buttons. Thomas Frank, who heads the Materials Technology Department at the Brazil site, explains the benefits of copper plating:
This pairs two materials with different strengths – cold-rolled steel strip delivers the mechanical properties such as stiffness, tensile strength, and elongation. In addition, the steel material provides load-bearing capacity and dimensional stability. Adding copper brings with it extremely high electrical conductivity, excellent contact properties, and stable electrical interfaces.
Homogeneous copper layer for uniform current flow
When used as an electrically conductive component, a uniform flow of current is essential, as a uniform current density not only ensures reliable electrical performance but also promotes even heat distribution, thereby helping to extend the component’s service life. Frank explains how this relates to the quality of the copper plating: “The homogeneity of the copper layer is crucial for a uniform flow of current. This means that it is important to optimize the strip for copper plating right from the start, so that the copper layer adheres perfectly throughout. Tight tolerances and reliable processes are essential. Finally, during the electroplating process, we ensure that the copper layer is applied extremely uniformly. By performing every step in-house – from cold rolling and copper plating to surface passivation – we ensure a seamlessly coordinated production process, which is a major advantage for our customers.” In this context, surface passivation adds an extra conversion layer to prevent the steel strip from oxidizing.
Copper coating makes complex forming operations possible
Galvanically copper-plated cold-rolled steel strip also stands out for its excellent formability – copper even adheres well to the steel substrate during deep-drawing processes and, thanks to its high ductility, is resistant to cracking. As Frank explains: “This is yet another example of how important the high quality we deliver is: When applied with absolute precision, copper has the potential to withstand even highly demanding forming operations – such as deep drawing or bending with large radii –when used as a thin surface coating on cold-rolled steel strip. Our products leverage this formability potential because we have precise control over the entire surface finishing process and monitor every step of it.”
Copper for efficient welding processes
According to Frank, it isn’t uncommon for copper surface coatings to also be used for efficient welding processes:
„Copper is excellent for welding. For this reason, cold-rolled steel strip with a copper coating on both sides is often used to manufacture double-walled tubes, which are used, for example, as brake or fuel lines in the automotive industry. In a continuous process, the cold-rolled steel strip is formed into a tube and joined together along the seam by brazing. The end result are tubes that are both durable and flexible.“
Copper-plated cold-rolled steel strip is the ideal solution wherever both mechanical strength and electrical performance are required. To ensure our customers can fully leverage these strengths, we advise them comprehensively throughout the entire process, as Frank explains: “As a reliable development partner, we bring our expertise to bear – from steel strip manufacturing to surface finishing. For our customers, this translates into a high-performance product that meets their requirements for further processing and subsequent performance properties in every respect.”
Copper plating coating thickness:
| Min. | Range | Max. |
|---|---|---|
| 1 µm | 4 µm | 7 µm |