Wire Bonding Improvement through Optimal Bonding Tools and Materials Selection

Traditionally, semiconductor capillaries and wires were individually developed because of their inherently different material and fabrication requirements, even though the performance of each component must complement the other during the wire bonding process for highest bondability and reliability. To further enhance performance, a combined capillary and wire solution was developed that significantly improved bonding performance levels. A 2N (99%) Au bonding wire, well known for its high-reliability performance, currently has narrow process windows. It was combined with a capillary re-engineered to improve the ultrasonic energy transmission between the wire and the bonding surface and therefore, enhance bondability. This combined solution was proven to be effective by the enlargement of the critical stitch bond process windows on Ag bonding surfaces. Two wire diameters, 1.0- and 0.6 mil, were used in the work to verify the effectiveness of the combined solution in both standard and ultra-fine pitch applications. The combined solution was tested in terms of bondability, high and ultra-low looping and high-temperature storage reliability at 200- degrees centigrade for 1,000 hours using leadframe and plastic PBGA devices at two different laboratories. A 3N (99.9%) Au wire, also well known for its high reliability and bondability performance, was added as a control parameter to better understand the significance of the combined solution.