Copper is the most widely used conductor material because of its fine electrical properties, durable physical properties and low cost. It can be easily formed and is available in a wide range of sizes and shapes. It can be used as a bare conductor or coated with silver, tin, nickel or other platings. Copper in its manufacturing process, will work harden. Consequently, it will have to be annealed in order to maintain its flexibility.
Copper Clad Steel
Copper clad steel was created to provide the industry with a conductor of much higher strength than ordinary copper. Although there is some loss of DC conductivity due to introduction of the steel, most applications are high frequency where loss would be detected due to the skin effect.
- Copper clad steel is commonly purchased in 30% and 40% conductivity.
- The percentage is of the conductivity of the copper clad steel versus the conductivity of regular annealed copper of equivalent size.
- Copper clad steel can be purchased in both hard drawn or annealed versions. The annealed version should be used when flexibility is desired.
Because copper and copper clad steel have limited flex life, alloys were designed to have high tensile strength and a long flex life. Cadminum copper, chromium copper, cadmium chrome and others were developed for this purpose. Although the high frequency conductivity is slightly lower than copper clad steel, the savings in weigh and the diameter reductions more than satisfied the applications when these alloys replaced copper clad steel. Because of the limited usage, alloys are more expensive than copper.
Although aluminum is similar to copper in most physical properties, there is only one advantage aluminum has over copper—weight. In applications requiring the lowest possible weight (such as aerospace related equipment), aluminum is used despite its termination problems and lower conductivity. Aluminum has had very limited usage in general purpose cable but is widely used in CATV and telephone applications.