With the move towards electrification in the transport industries, automotive and aerospace companies are looking to aluminium wire for electronics uses. Being cheaper than gold, aluminium is suitable for ultrasonic wedge bonding and eliminates the ‘purple plague’ associated with bonding gold wire to aluminium pads or substrates.
Microelectronic aluminium wire bonding tends to use 5/9s pure aluminium, 4/9s pure aluminium, or 0.5% Mg aluminium alloy, each of which deliver their own unique properties. 5/9s wire is preferred for high power applications, where it is easier to bond due to the increased elongation making the wire softer. 4/9s wire is often doped with nickel to improve corrosion resistance, allowing it to be used in a wider range of applications.
You can find out more about wire bonding with aluminium (and gold) here:
https://www.twi-global.com/technical-knowledge/faqs/what-is-wire-bonding
