Detailed Explanation of Coaxial Cable Inner Conductor Material

The inner conductor materials of coaxial cables are diverse, generally including copper-clad steel, silver plated copper, tin plated copper, etc. This article will briefly introduce the characteristics and advantages of these three materials.

1, Copper clad steel

Copper clad steel wire is a composite wire with steel wire as the core and a layer of copper covering its surface. Copper clad steel wire combines the mechanical properties of high strength and high-temperature softening resistance of steel with the electrical properties of high conductivity and low contact resistance of copper. Therefore, it has the characteristics of high conductivity, low material cost, high tensile strength, light weight, and wear resistance. It can replace copper conductors in the cable industry as conductors for high and low frequency transmission cables in the communication industry. Copper clad steel wire combines the high strength of steel with the high conductivity and corrosion resistance of copper, making it an ideal wire in the communication, power, and electronics industries. The thicker the copper layer wrapped around the steel surface, the higher the DC conductivity.

Copper clad steel wire can be divided into three types based on conductivity: 21% IACS, 30% IACS, and 40% IACS (IACS international annealed copper standard conductivity). Copper clad steel wire can be divided into soft state (A), hard state (HS), and superhard state (EHS) according to its mechanical properties (annealed state). Generally, RF cables use soft copper-clad steel with 30% or 40% IACS as the inner conductor.

2, Silver plated copper

Silver plated copper wire is made by concentric plating of a silver layer on a copper core. It combines the characteristics of two metals, has good conductivity, a bright and glossy surface, and the silver layer has high corrosion resistance. Due to these advantages, silver plated copper wire has become the preferred choice for high-frequency wires.

Silver plated copper wire is divided into silver plated soft round copper wire and silver plated hard round copper wire. Silver plated soft round copper wire is annealed to change its physical properties in order to achieve softening. A good silver plated copper wire coating is continuously and firmly attached to the surface of the conductor, and the sample surface remains black after being tested. The surface of the silver plated coating should be smooth and continuous, without harmful defects such as silver particles, burrs, mechanical damage, etc.

Its performance characteristics include high conductivity and high-frequency characteristics (currently, most cables with high performance requirements use silver plated copper as the inner conductor, such as low loss cables and testing cables. The application scenarios are mostly in the aerospace and military fields). High temperature resistance, operating temperature range of -60 ℃~+250 ℃, and corrosion resistance.

3, tinned copper

Tin plated copper refers to a thin layer of metallic tin plated on the surface of copper, as tin forms a thin film of tin dioxide in air, thereby preventing copper from being oxidized. Tin can also form a thin film with halogens that has a similar effect. Therefore, it has good corrosion resistance, certain strength and hardness, good formability and easy welding, non-toxic and odorless tin layer, and a bright surface.

The main purpose of tin plating copper is to prevent oxidation of copper. In the cable series, tin plated copper conductors are also used as inner conductors, but they are more commonly chosen as outer conductors (tin plated copper wire braided) like semi flexible cables.