wire bonding

Wire bonding connects die bond pads to package leads or substrate using thin metal wires (typically 15-50μm diameter gold or aluminum), providing electrical connections in traditional packaging. The process uses thermocompression, ultrasonic energy, or both to form metallurgical bonds. Ball bonding (most common) forms a ball at the wire end using electric flame-off, bonds it to the die pad, routes the wire to the package lead, and forms a crescent bond before cutting. Wedge bonding forms wedge-shaped bonds at both ends without ball formation. Wire bonding is mature, reliable, and cost-effective for moderate I/O counts and frequencies. Typical bond pad pitch is 40-100μm with wire lengths of 1-5mm. Wire bonding supports high-temperature applications and is widely used in automotive, industrial, and consumer electronics. Limitations include inductance from wire length (1-5nH), limited bandwidth, and susceptibility to wire sweep during molding. Advanced wire bonding uses copper wire for lower resistance and cost. Wire bonding is gradually being replaced by flip-chip for high-performance applications but remains dominant for cost-sensitive and moderate-performance devices.