gold wire bonding

**Gold Wire Bonding** is a semiconductor interconnect technique using thin gold wire (15-50μm diameter) to connect die bond pads to package lead frames or substrates. ## What Is Gold Wire Bonding? - **Material**: 99.99% pure gold (4N) or gold alloys - **Process**: Thermosonic bonding at 150-220°C - **Bond Types**: Ball bond (1st bond) and stitch bond (2nd bond) - **Speed**: 15-25 wires per second on modern equipment ## Why Gold Wire Bonding Matters Gold has been the industry standard for decades due to excellent conductivity, corrosion resistance, and reliable ball formation. ```svg Gold Wire Bonding — A Thermosonic Electrical Bridge heat, force, and ultrasonic motion weld a gold ball to the die pad and a stitch to the package lead PACKAGE CROSS-SECTION DURING FIRST-BOND FORMATION die paddle / copper leadframe package lead SILICON DIE active circuitry below passivation die attach Al BOND PAD BALL BOND Au wire ceramic capillary force F ultrasonic scrub STITCH / WEDGE BOND loop height bond span heated stage FORCEULTRASONICHEAT plastic deformation + oxide disruption + atomic contact mold flow wire sweep if loop is weak BALL / PAD INTERFACE · CONTROL INTERMETALLIC GROWTH Au ballAu–Al intermetallicAl pad excess time / temperature brittle phases + Kirkendall voiding increase contact resistance or lift risk MECHANICAL FAILURE LOCATIONS heel crack stitch lift pull / shear tests expose weak bonds Reliable wire bonds balance ball deformation, loop geometry, metallurgical compatibility, molding forces, and lifetime temperature. ``` **Gold vs. Copper Wire**: | Property | Gold | Copper | |----------|------|--------| | Cost | High ($60/oz) | Low ($0.30/oz) | | Conductivity | Good | Better | | Corrosion | Excellent | Needs protection | | Bond force | Lower | Higher | Gold remains preferred for high-reliability automotive and aerospace applications.

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