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Wire bonders are a class of semiconductor packaging equipment that attach fine metallic wire between an integrated circuit die and its package leads or substrate. By this method, electrical connections are made between the die's bond pads and the external terminals of the package, enabling signal and power transfer to the outside world. Wire bonders are a key part of the assembly and packaging stage of semiconductor production, where individual chips are turned into finished, mountable devices.

Wire bonding typically employs a thermosonic process that combines ultrasonic vibration, heat, and pressure to create a metallurgical weld between the wire and the bond pads. The bonder feeds a continuous length of wire through a capillary tool, which is positioned over the first bond pad on the die. A small ball is formed at the wire tip and then pressed onto the bond pad while ultrasonic energy is applied, creating a strong first bond.

After the first bond is formed, the machine guides the tool in a controlled loop from the die to the second bond point, typically on a lead frame or substrate. The wire is then bonded in a stitch or wedge configuration, and the wire is subsequently cut off to complete the interconnection. The process is repeated for every pad on the die, building up a complete set of wire connections within the package.

Wire bonding takes place in the back-end of semiconductor manufacturing, after wafer fabrication and die singulation, and typically follows the die attach step in which the die is mounted onto a lead frame or substrate. The wire-bonded package then proceeds to encapsulation, where it is sealed in a molding compound to protect the delicate wires and die from environmental damage.

The finished packages subsequently go through processes such as deflashing, trimming and forming of the leads, marking, and final electrical testing before shipment. In the overall flow, wire bonding converts the bare die into an interconnected, packageable component, making it an essential step between die preparation and the final assembled product.