Copper-clad aluminium wire (CCAW or CCA) is a dual-metal

electrical conductor In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. The flow of negatively c ...

composed of an inner

aluminium Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

core and outer

copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...

cladding.

Production

A copper strip is formed into the shape of a cylinder, while it is being wrapped around an aluminum core and the edges of the copper strip are welded together. The assembly is then pulled through a die, where the cladded wire is squeezed and stretched while also improving the bonding between the copper and the aluminum core.

Uses

The primary applications of this conductor revolve around weight reduction requirements. These applications include high-quality coils, such as the

voice coil A voice coil (consisting of a former, collar, and winding) is the coil of wire attached to the apex of a loudspeaker cone. It provides the motive force to the cone by the reaction of a magnetic field to the current passing through it. Th ...

s in

headphones Headphones are a pair of small loudspeaker drivers worn on or around the head over a user's ears. They are electroacoustic transducers, which convert an electrical signal to a corresponding sound. Headphones let a single user listen to an ...

or portable

loudspeaker A loudspeaker (commonly referred to as a speaker or, more fully, a speaker system) is a combination of one or more speaker drivers, an enclosure, and electrical connections (possibly including a crossover network). The speaker driver is an ...

s; high frequency coaxial applications, such as RF antennas and

cable television Cable television is a system of delivering television programming to consumers via radio frequency (RF) signals transmitted through coaxial cables, or in more recent systems, light pulses through fibre-optic cables. This contrasts with bro ...

distribution cables; and power cables. CCA was also used in

electrical wiring Electrical wiring is an electrical installation of Electrical cable, cabling and associated devices such as switches, distribution boards, sockets, and light fittings in a structure. Wiring is subject to safety standards for design and in ...

for buildings. The copper/aluminium construction was adopted to avoid some of the problems with aluminium wire yet retain most of the cost advantage. Its low copper content makes it unattractive to copper thieves. CCA is also seen in counterfeit

unshielded twisted pair Twisted pair cabling is a type of communications cable in which two conductors of a single Electronic circuit, circuit are twisted together for the purposes of improving electromagnetic compatibility. Compared to a Single-ended signaling, sin ...

networking cables. These cables are often less expensive than their full-copper counterparts, but the official specifications such as Category 6 require conductors to be pure copper. This has exposed the manufacturers or installers of cable with fake certification to legal liabilities.

Properties

The properties of copper-clad aluminium wire include: * Less expensive than a pure copper wire * Lighter than pure

* Higher

electrical conductivity Electrical resistivity (also called volume resistivity or specific electrical resistance) is a fundamental specific property of a material that measures its electrical resistance or how strongly it resists electric current. A low resistivity in ...

than pure

* Higher strength than aluminium * Electrical connections typically more reliable than pure aluminium{{Citation needed, date=December 2015

Disadvantages

* Easily sold as counterfeit

copper wire Copper has been used in electrical wiring since the invention of the electromagnet and the telegraph in the 1820s. The invention of the telephone in 1876 created further demand for copper wire as an electrical conductor. Copper is the electri ...

to unaware clients * Much more prone to mechanical fatigue failure than pure copper wire * Gets much hotter than pure copper in case of severe overcurrent, such as short circuits, although this is not an issue for code-compliant installations with proper fuses or

circuit breaker A circuit breaker is an electrical safety device designed to protect an Electrical network, electrical circuit from damage caused by current in excess of that which the equipment can safely carry (overcurrent). Its basic function is to interr ...

Skin effect

The

skin effect In electromagnetism, skin effect is the tendency of an alternating current, alternating electric current (AC) to become distributed within a Conductor (material), conductor such that the current density is largest near the surface of the conduc ...

forces

alternating current Alternating current (AC) is an electric current that periodically reverses direction and changes its magnitude continuously with time, in contrast to direct current (DC), which flows only in one direction. Alternating current is the form in w ...

to flow on the outer periphery of any wire; in this case, the outer copper cladding of the conductor which has lower resistance than the mostly unused aluminum interior. The better conductor on the outer path causes the wire's resistance at high frequencies, where the

is greater, to approach that of a pure copper wire. This improved conductivity over bare aluminum makes the copper-clad aluminium wire a good fit for

radio frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the u ...

use. The skin effect is similarly exploited in

copper-clad steel Copper-clad steel (CCS), also known as copper-covered steel or the trademarked name Copperweld is a bi-metallic product, mainly used in the wire industry that combines the high mechanical strength of steel with the conductivity and corrosion re ...

wire, such as the center conductors of many

coaxial cable Coaxial cable, or coax (pronounced ), is a type of electrical cable consisting of an inner Electrical conductor, conductor surrounded by a concentric conducting Electromagnetic shielding, shield, with the two separated by a dielectric (Insulat ...

s, which are commonly used for

high frequency High frequency (HF) is the ITU designation for the band of radio waves with frequency between 3 and 30 megahertz (MHz). It is also known as the decameter band or decameter wave as its wavelengths range from one to ten decameters (ten to one ...

feedlines with high strength and conductivity requirements.

References