Wire bonding is the part of the fabrication that allows an electrical component to communicate with the outside world. A thin electrically conductive wire – typically gold, aluminium, copper or silver – is used to allow electricity to flow from contacts on the component to, or from, its packaging. There are two commonly used types of wire bonding – wedge and ball. Which one is more suitable depends on the substrate, the contact material, the bonding material, and a number of other physical factors. Bonders can be manual or automated, and some can feature pattern recognition software to help speed the bonding process up.
Bonding a wafer to another wafer is a step commonly used when packaging components in an micro or nanoelectrical device. It can help a form new functions in a device, or can ensure mechanical and hermetic encapsulation of devices and electronics. The result is irreversible.Common bonding methods include using heat or with an adhesive for thermally sensitive samples.
Annealing is a process that can reduce residual stress in a substrate that has accumulated during prior processes such as deposition.The material is heated to high temperatures and allowed to cool at a controlled rate. This allows the material’s crystal structure to relax into a less intrinsically stressed state, and to settle into a more desirable microstructure as it cools.