Wire bonding is a method of making interconnections between a microchip and the outside world as part of semiconductor device fabrication.

The wire is generally made up of one of the following:

• Gold
• Aluminum
• Copper

Wire diameters start at 15µm and can be up to several hundred micrometres for high-powered applications.

There are two main classes of wire bonding:

• Ball bonding
• Wedge bonding

Ball bonding usually is restricted to gold and copper wire and usually requires heat. Wedge bonding can use either gold or aluminum wire, with only the gold wire requiring heat.

In either type of wire bonding, the wire is attached at both ends using some combination of heat, pressure, and ultrasonic energy to make a weld.

Wire bonding is generally considered the most cost-effective and flexible interconnect technology, and is used to assemble the vast majority of semiconductor packages.