Introduction to the Copper Conductivity Materials Database
This section introduces copper conductivity materials (coppers and copper alloys) for electrical applications and provides details of properties and uses.
Copper has the highest conductivity of any non-precious metal. This, combined with its high ductility, good machinability, high strength, ease of jointing and good resistance to corrosion, makes copper the first choice as a conductor for electrical applications.
High conductivity copper is the most common form of the metal and it is widely available with consistent high quality. It is the first choice for the manufacture of bulk conductors such as cables, busbars, transformer windings and motor stators and rotors. However, for other electrical applications, such as connector parts, commutators and catenary wires, the mechanical properties may need to be enhanced by the addition of appropriate alloying elements. The ease with which copper can form alloys with other elements results in the availability of a very wide range of materials suitable for the full range of electrical applications.
As mechanical properties are enhanced by the addition of alloying elements, there is a trade off with a reduction in electrical conductivity.
The graph below shows how the addition of various alloying elements affects the conductivity of copper.
This graph plots tensile strength and conductivity for different copper alloys.
A downloadable reference publication, High Conductivity Copper for Electrical Engineering (Publication 122) describes the electrical and mechanical properties of high conductivity copper and copper alloys that are intended for use in electrical applications. It is primarily aimed at electrical engineers rather than metallurgists, but gives the basic metallurgical detail needed to understand the processing requirements of alloys.
The content in this section serves as an introduction to each copper conductivity material.
Copper Conductivity Material Selection Menu
Browse the coppers and copper alloys below, grouped by property, or use the Alloy Properties Table to link to information on individual alloys, including specifications, mechanical and physical properties, available product forms and applications.
Very High Conductivity
The standard copper for conducting electricity via wire, cables and busbars, with 100% IACS, is Cu-ETP. For special applications, such as vacuum, Cu-OF is used. Very small additions of alloying elements (e.g. silver, tin, tellurium) increase softening resistance at the expense of conductivity, whilst Cu-C offers a high conductivity (98% IACS) cast option. The coppers listed here have a minimum conductivity of 98% IACS.
High Conductivity + High Tensile Strength
Small additions of alloying elements (e.g. tin, magnesium, chromium, iron, zirconium) increase the strength of copper at the expense of conductivity. Applications include overhead grooved contact wires for trams and railways and high duty power cables. The coppers listed in this section have a minimum conductivity of 64% IACS and a minimum tensile strength of 460 N/mm2.
High to Very High Conductivity + Resistance to Softening
Small additions of alloying elements (e.g. tin, silver, chromium, zirconium, iron) increase the softening resistance of copper at the expense of conductivity. Applications include electric motors, generators, power cables and welding electrodes which run at high temperatures, whilst requiring excellent conductivity. Coppers in this section have a conductivity ranging from 64–100% IACS and a temperature limit minimum of 250°C.
High Conductivity + Resistance to Softening + High Tensile Strength
A small addition of iron gives the best combination of resistance to softening, strength and conductivity. The main application of this alloy is in leadframes. This copper has a conductivity of 90% IACS, a temperature limit of 360°C and a tensile strength of 500 N/mm2.
Good to High Conductivity + High Tensile Strength
The addition of small amounts of beryllium, nickel and silicon give heat treatable alloys of very high strength with good conductivity. Applications include contact springs, switchgear and stressed automobile components. These alloys also have the highest fatigue strength. The copper alloys in this section have a conductivity ranging from 44-98% IACS and a minimum tensile strength of 500N/mm2.
High Conductivity + Good Machinability
Additions of tellurium or sulphur to copper provide free machining properties needed for high precision CNC machining of components such as semi-conductor mounts, vacuum interrupters, plasma nozzles and resistance welding tips. These coppers range in conductivity from 64–98% IACS and have a minimum machinability index of 80%.
For components such as press-fit pins and contact springs, high strength and hardness with good conductivity is given by copper-nickel-silicon and copper-beryllium. These alloys range in conductivity from 45–60% IACS and have a minimum hardness of 220 HV.
Very High Conductivity + Good Castability
For complex shapes such as electrical switch gear which cannot be made by the use of wrought alloys, cast copper with a conductivity of up to 98% IACS may be used.
Low Conductivity + Excellent Castabilty
These brasses are much easier to cast for heavy duty components which only require low conductivity. They have conductivities in the region of 20% IACS.
Low Conductivity + Excellent Machinability
This leaded brass has the best machinability of any metallic alloy and offers a more cost-effective solution when only low conductivity is required. It has a conductivity of 22% IACS and a machinability index of 100%.
Low to Good Conductivity
The binary copper-zinc brasses are a cost effective choice for electrical applications which require a low (28% IACS) to good (56% IACS) electrical conductivity.
Alloy Properties Table
Indicative values are given in the table below for the most important mechanical and physical properties. Alloys are ordered in decreasing electrical conductivity. Click the alloy’s ISO designation to go to further information.
|Alloy||% IACS||%Tensile Strength N/mm2||Proof Strength||Elongation %||Hardness HV||Thermal Conductivity
|Index %||Temp. Limit oC|
|Oxygen-free High Conductivity Copper
|Electrolytic Tough Pitch Copper
|Electrolytic Tough Pitch Copper
|Oxygen-free Extra Low Phosphorus Copper
|Silver-bearing Tough Pitch Copper
|Silver-bearing Oxygen-free Copper
|Phosphorus Deoxidised Tough Pitch Copper