Industrial uses of gold

Abstract

The industrial uses of gold are growing and today probably consume about 15% of the world's output of newly mined metal. Gold or gold alloys are chosen essentially for their resistance to tarnishing and oxidation at room and elevated temperatures, their corrosion resistance, or their selective reflectivity of radiation (which includes their colour). As a material for electrical make-and-break contacts operating with light pressures and controlling small currents, gold has the advantages that it is free from high-resistance oxide and sulphide films and also that it does not, like platinum, catalyse the breakdown of organic vapours to form black deposits on the contact surface. Among the disadvantages of gold are its tendency to weld on closure and its softness, which readily allows dust particles to become embedded and thus perhaps interfere with good contact between surfaces; alloying may be useful in overcoming this. Gold, often lightly alloyed and applied as an. electrodeposit, is extensively used in semiconductor assemblies and to form conducting paths, solderable surfaces, and contacting fingers in printed circuits. Other important applications are as corrosion-resistant spinnerettes (as a Pt-Au alloy) for extruding rayon fibres, as solder for high-temperature operations, and as reflective films, particularly for infra-red radiation.