Drahtbond

Drahtbond, known in English as wire bonding, is a method used to make electrical connections between a semiconductor die and a package lead or substrate by attaching a fine wire. It is a dominant interconnect technology in small- to medium-scale integrated circuits and electronic modules.

Two main bonding techniques are used: ball bonding and wedge bonding. Ball bonding forms a small spherical tip at the end of the wire and bonds it to the die pad and then to the lead or substrate using ultrasonic energy and sometimes heat (thermocompression). Wedge bonding uses a sharp wedge tool to form bonds, typically with ultrasonic energy and sometimes heat as well. The choice of technique depends on device geometry, materials, and required reliability.

Common bonding wires are made of gold, aluminum, or copper. Gold wires (often in the 18–25 micrometer range) provide high reliability and corrosion resistance, while aluminum and copper offer cost and performance advantages in modern designs. The pads on the die and the bonding sites on the leadframe or substrate are made of compatible metals or coated with surface finishes to promote reliable bonding.

Equipment and process control are critical, including precise wire feeding, capillary or wedge tools, and control of bonding force, ultrasonication, and temperature. Process developers optimize loop lengths, bond counts, and bond strength to ensure mechanical robustness and electrical integrity over the device’s lifetime.

Applications span semiconductor devices, memory modules, sensors, and automotive and industrial electronics. Drahtbonding remains a versatile, cost-effective interconnect method, though it competes with alternatives such as flip-chip and alternatives that use copper or advanced packaging techniques.