Copper Wire Bonding is a semiconductor interconnect technique using copper wire as a lower-cost alternative to gold wire, now dominant in high-volume packaging.

What Is Copper Wire Bonding?

• Material: 99.99% pure copper (4N Cu) or palladium-coated copper
• Process: Thermosonic bonding, similar to gold but higher force/power
• Advantage: 90%+ cost reduction vs. gold wire
• Challenge: Oxidation prevention requires forming gas (N₂/H₂)

Why Copper Wire Bonding Matters

With gold at $60+/oz vs copper at $0.30/oz, the cost savings for high-volume products like smartphones is substantial—millions of dollars annually.

Copper vs. Gold Wire Bonding:
Property        | Gold      | Copper
----------------|-----------|----------
Material cost   | High      | Very low
Ball hardness   | Soft      | Hard
Bond force      | Low       | 2-3× higher
Pad damage risk | Low       | Higher
Oxidation       | None      | Requires N₂/H₂
Conductivity    | Good      | Better (10%)

Process Requirements for Copper:

• Forming gas atmosphere (95% N₂ / 5% H₂) or nitrogen
• Higher bonding force and ultrasonic power
• Specialized capillaries for harder material
• Enhanced FAB (free air ball) formation control