Element of the Month
Each month we will explore elements of interest from the periodic table, with a brief history of discovery and development, and a review of uses and applications.
Copper - Atomic Number: 29 - Chemical Symbol: Cu
Copper is a ductile reddish-gold metal. Artefacts dating back to 9000 BC have been found, and the development of copper alloys with tin around 2500 BC heralded the start of the Bronze Age.
It is a very good conductor of heat and electricity.
Copper helps enzymes transfer energy in human cells, and is an essential element for health.
Copper is toxic in excess.
As a Pure Element
Copper is predominantly used in electrical wiring and motors, because its electric current carrying capacity is very good. It is also widely used in plumbing systems and heat exchangers.
Printed circuit boards (PCB) use layers or tracks of copper to interconnect electronic components, and multi-layer PCB use copper coated through-holes of less than 1mm diameter to make connections between layers. Copper is electroplated into the hole and the deposit thickness is critical for correct operation of the finished electronic assembly. Learn more
It is an important part of the distilling process, converting sulphur fermentation by-products that would otherwise spoil the spirit into copper sulphate that adheres to the internal walls of the still and is washed out at the end of the process.
Electroplated copper is used as an initial levelling coat to improve surface finish in decorative applications such as costume jewellery and injection moulded plastics, or as a barrier layer for brass in connector manufacture. Learn more
It is also used in selective case hardening of steel alloys, where an approximately 25 µm thick copper layer is used to prevent diffusion of carbon or nitrogen in areas that are not to be hardened.
As an Alloy
There are many alloys that contain copper, including brass (copper-zinc), nickel silver (copper-nickel-zinc), and bronze (copper-tin)
Binary and ternary alloys of copper are electroplated for a number of purposes: –
- Brass (copper-zinc) – decorative – lamps & domestic fittings
- Yellow bronze (copper-tin) – functional – anti-galling coating used in oil and gas drilling cutters; also, an alternative to a nickel barrier layer in gold plated jewellery
- White bronze – functional – protective finish on brass connector shells; also, an alternative to a nickel barrier layer in plated jewellery
As a Compound
There are many copper compounds with a wide range of uses but probably the most important is in agriculture, where fungicides based on copper sulphate are effective controls over a very wide range of diseases in fruit trees and bushes, flowers, arable, and root crops.
Here are some key parameters for copper, quantifiable using instruments from Helmut Fischer GmbH
- Thickness of copper coatings on steel – in the range ~ 4 to 100 µm, measurable with a contacting probe instrument such as the Deltascope FMP30
- Thickness of copper coatings on brass, aluminium, or plastics – in the range ~ 4 to 30 µm, measurable using an instrument such as the Fischerscope XDL 230
- Thickness of copper layers on printed circuit boards and EMC shielding, measurable using an instrument such as the Fischer SR-Scope RMP30-S
- Fischer Phascope PMP10
- Thickness + composition of binary alloy coatings such as copper-tin on large components – in the range ~ 4 to 30 µm, measurable using an instrument such as the Fischerscope XAN 500
- Thickness + composition of ternary alloy coatings such as copper-tin-zinc on small connector components – in the range ~ 3 to 10 µm, measurable using an instrument such as the Fischerscope XDAL SDD