New copper conductors for high-frequency cables
Wide, ultra-thin silver-plated copper foil combines advantages of metal foils with precision electroplating for the RF industry and shielding applications.
Research and development for shielding material and electrical conductors is facing more demanding requirements from manufacturers in the high frequency cable market. Materials that provide an effective protection against EMI distortion are crucial for the industry. Not only do airplanes, satellites, and medical equipment rely on the transmission of high-speed digital signals free of any interference, but the consequences of any failure can be severe in these applications.
RF shielding and conductor materials are often based on copper with an electrodeposited layer of silver on the surface. The silver does not only increase the insulation (skin effect), but also protects the copper from corrosion (red plague). Historically, manufacturers used silvered copper wire for the shielding where the center conductor of the RF cable was wrapped outside with the insulation material. Equally important for an effective shielding are also the cable assemblies and connectors which have to be insulated as well.
New development focuses on materials with higher flexibility, reduced thickness, greater width, and extended lifetime. Elkem Inc and SCHLENK Metal Foils have started a partnership in the field of RF shielding to provide such enhanced materials. While SCHLENK specializes on metal strips as an alternative to wire, Elkem provides silver-plating of the copper surface.
Rolled copper foil, slit to strips
In the metal foils industry, SCHLENK is an industry leader, providing thinnest foils down to a thickness of .00025”. The foil is rolled in wide gauges and slit to size, either in coils up to 26” or in narrow strips down to .025”. Compared to the oval shape of flat-rolled wire, the foil provides an even shape and fine edges based on a precision slitting process. The silver can also be applied evenly in the plating process, resulting in a very uniform thickness tolerance. The characteristic of slit foil leads to a superior behavior at bending with ultimate durability.
Over the last decades, SCHLENK has become the market leader for plain, precise copper conductors in flexible flat cables, airbags, and heated windshields for the automotive industry. “In partnership with Elkem’s precision plating processes, we are very excited to offer this superior performance product to the high-frequency cable market,” confirmed Thorben Beckmann, National Sales Manager of SCHLENK.
Silver layer by precision electroplating
Headquartered in New Jersey, Elkem Inc is qualified to provide customers with a variety of metal plating finishes. Their equipment can accommodate metal ribbons up to .350” width and apply precise coatings of silver, tin, gold, and nickel from 5 up to 1,500 microinches. With over 50 years in the plating industry, their experience with RF cable applications allows them to provide the highest quality based on ASTM standards. Elkem is both an American family-owned business and an active member of the Wire Association International.
“We are extremely enthusiastic about the collaboration with SCHLENK and see a lot of potential,” said Jeff Lawrence, Vice President of Elkem and the WAI. This year, Elkem will further invest into additional plating equipment to provide increased capacity to the market. Additionally, Elkem has continued to expand its testing capabilities through acquisition of state-of-the-art thickness measuring equipment.
Wide aspect ratios and high flexibility
The market calls for wider and thinner materials that provide reduced sizes and weights. With the partnership of both manufacturers, aspect ratios of 400:1 will be possible in future (based on a .0006” thin and .275” wide foil). While wider and thinner materials provide increased flexibility, the conductivity and surface quality of these materials has to meet stringent requirements. SCHLENK foils will be able to cater to these requirements by providing industry-best edge quality and reduced stress on the edges. Durable materials that withstand long periods and millions of flex cycles will surpass current engineering requirements in the aerospace and automotive industry.
Engineers for RF materials will now be able to design smaller diameter in addition to more elastic cables. Additionally, these performance plated foils will offer next-level technical advantages for future applications in the EV Storage Market and Autonomous Driving. For the navigation of vehicles, further optimized and compact RF conductors will be required. Eventually, robotics and industry 4.0 will also look for such components. SCHLENK’s proprietary roll-clad technique offers a unique flatness and variety of material combinations for wider foils in these niche markets.
The RF shielding materials and conductors provided by Elkem and SCHLENK are available now from R&D sample quantities through full volume production. Stocking programs are also available for customers who require short lead times and Just-In-Time delivery. Both companies will present their joint products to the public this year. In May, Elkem will exhibit at the upcoming INTERWIRE Trade Show in Atlanta, GA while SCHLENK Metal Foils will focus on The Battery Show in Novi, MI later in fall. Representatives from Elkem and SCHLENK will be available at both shows for technical questions and support regarding these product lines.