Wire strength of Cu wire on al metallization after high temperature reliability

Copper wire has been introduced to replace gold or aluminum wires and gets a lot of attention due to advantages below: 1. Copper wire material cost is much lower than gold wire. 2. Faster UPH compared to aluminum wire bonder. 3. Better electrical performance in comparison with gold or aluminum wires. 4. Better thermal performance than gold or aluminum wires. To further understand the behavior and limitation about the Cu-Al system, it is essential to investigate the the reliability of the Cu wire bonds under stress, especially with current demanding applications within consumer and automotive markets. The objective of this investigation is to evaluate the wire bonding reliability of Cu wires on Al based metallizations in comparison with Au wires. Metallurgical analysis was also carried out to assess the interface reliability after thermal storage.