Electronics and related devices

Copper electrical busbars distributing power to a large building

The electrical properties of copper are exploited in copper wires and devices such as electromagnets. integrated circuits and printed circuit boards increasingly feature copper in place of aluminium because of its superior electrical conductivity; heat sinks and heat exchangers use copper as a result of its superior heat dissipation capacity to aluminium. Vacuum tubes, cathode ray tubes, and the magnetrons in microwave ovens use copper, as do wave guides for microwave radiation.

Architecture and industry

Copper roof on the Minneapolis City Hall, coated with Patina

Because of the waterproof nature of copper, it has been used as the roofing material of many buildings since ancient times. The green colour on these buildings is due to a long-term chemical reaction: copper is first oxidised to copper(II) oxide, then to cuprous and cupric sulfide and finally to copper(II) carbonate, also called verdigris, which is highly corrosion-resistant. The copper used in this application is phosphorus deoxidized copper (Cu-DHP).  Lightening rods use copper as a means to divert electric current throughout the ground instead of destroying the main structure.  Copper has excellent brazingand soldering properties and can be welded; the best results are obtained with gas metal arc welding.

Copper in alloys

The alloy of copper and nickel, called cupronickel, is used in low-denomination statuary coins, often for the outer cladding. The US 5-cent coin called nickel consists of 75% copper and 25% nickel and has a homogeneous composition. The 90% copper/10% nickel alloy is remarkable by its resistance to corrosion and is used in various parts being exposed to seawater. Alloys of copper with aluminium (about 7%) have a pleasant golden color and are used in decorations.  Copper alloys with tin are part of lead-free solders.