Ball bonding

Ball bonding is a type of wire bonding, and is the most common way to make the electrical interconnections between a chip and the outside world as part of semiconductor device fabrication.

Gold or copper wire can be used, though gold is more common because its oxide is not as problematic in making a weld. If copper wire is used, nitrogen must be used as a cover gas to prevent the copper oxides from forming during the wire bonding process. Copper is also harder than gold, which makes damage to the surface of the chip more likely. However copper is cheaper than gold and has superior electrical properties, and so remains a compelling choice.