Copper-clad aluminium wire, commonly abbreviated as CCAW or CCA, is a electrical conductor

Electrical conductor

In physics and electrical engineering, a conductor is a material which contains movable electric charges. In metallic conductors such as copper or aluminum, the movable charged particles are electrons...

 composed of an inner aluminium

Aluminium

Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....

 core and outer copper

Copper

Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...

 cladding

Cladding (metalworking)

Cladding is the bonding together of dissimilar metals. It is distinct from welding or gluing as a method to fasten the metals together. Cladding is often achieved by extruding two metals through a die as well as pressing or rolling sheets together under high pressure.The United States Mint uses...

.

Uses

The primary applications involve of this conductor revolve around weight reduction requirements. These applications include high-quality coil

Coil

A coil is a series of loops. A coiled coil is a structure in which the coil itself is in turn also looping.-Electromagnetic coils:An electromagnetic coil is formed when a conductor is wound around a core or form to create an inductor or electromagnet...

s, such as the voice coil

Voice coil

A voice coil 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...

s in headphones

Headphones

Headphones are a pair of small loudspeakers, or less commonly a single speaker, held close to a user's ears and connected to a signal source such as an audio amplifier, radio, CD player or portable Media Player. They are also known as stereophones, headsets or, colloquially, cans. The in-ear...

, portable loudspeaker

Loudspeaker

A loudspeaker is an electroacoustic transducer that produces sound in response to an electrical audio signal input. Non-electrical loudspeakers were developed as accessories to telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally useful...

s or mobile coils; high frequency coaxial applications; such as RF antennas; CATV distribution cables; and power cables.

CCA was also used in mains cable

Electrical wiring

Electrical wiring in general refers to insulated conductors used to carry electricity, and associated devices. This article describes general aspects of electrical wiring as used to provide power in buildings and structures, commonly referred to as building wiring. This article is intended to...

 for domestic and commercial premises. The copper/aluminium construction was adopted to avoid some of the problems with aluminium wire

Aluminium wire

Aluminum wire is a type of wiring used in houses, power grids, and airplanes. Aluminum provides a much better conductivity to weight ratio than copper, and therefore is used in power wiring of some aircraft....

, yet retain some of the cost advantage. But, solid copper is most commonly used in internal residential 120v or 240v wiring in the US.

CCA became extremely popular on emerging markets as a cheap replacement for copper category 5e twisted pair

Twisted pair

Twisted pair cabling is a type of wiring in which two conductors are twisted together for the purposes of canceling out electromagnetic interference from external sources; for instance, electromagnetic radiation from unshielded twisted pair cables, and crosstalk between neighboring pairs...

 cables.

Properties

The properties of copper-clad aluminium wire include:

• Lighter than pure copper
• Higher electrical conductivity than pure aluminium
• Higher strength than aluminium
• Better solderability than aluminium, due to the lack of the oxide layer which prevents solder adhesion when soldering bare aluminium.
• Less expensive than a pure copper wire
• Typically produced as a 10% or 15% by copper volume product

Skin effect

The skin effect

Skin effect

Skin effect is the tendency of an alternating electric current to distribute itself within a conductor with the current density being largest near the surface of the conductor, decreasing at greater depths. In other words, the electric current flows mainly at the "skin" of the conductor, at an...

 causes alternating current

Alternating current

In alternating current the movement of electric charge periodically reverses direction. In direct current , the flow of electric charge is only in one direction....

 to concentrate on the more-conductive copper cladding of the conductor, causing the resistance of the wire to approach that of a pure copper wire at high frequencies, which makes the copper-clad aluminium wire a good fit for such applications.
The skin effect is also utilized in copper-clad steel wire such as RG-6

RG-6

RG-6/U is a common type of coaxial cable used in a wide variety of residential and commercial applications. The term "RG-6" itself is quite generic and refers to a wide variety of cable designs, which differ from one another in shielding characteristics, center conductor composition, and...

coax, which is also commonly used in high frequency applications with high strength requirements.