Advanced interconnect equipment and process development

With increased demand for higher reliability in power modules and the automotive industry, aluminum-based interconnects are becoming one of the bottlenecks in module performance and will potentially be replaced by copper-based advanced interconnects. This paper lists the challenges that have to be overcome before the replacement can really happen, and introduces solutions that K&S is working on to overcome those challenges. An overall solution consisting of equipment, bond heads, consumables, and bonding processes is being developed and provided to customers for evaluation. A configurable bond head with critical features was developed to enable the advanced interconnect development, providing enough ultrasonic power, bond force, and cutting system rigidity. It can be easily reconfigured within an hour, among 3 configurations, to test different bonding materials and packaging platforms. To improve consumable lifetime, a ridged bond tool (a K&S patented design), that has better coupling to copper (Cu) wire, and a cutter blade, made of wearable material, were developed and demonstrated to have a >100,000 bond life time. The bonding mechanism for Cu-based bonding materials is sophisticated and very different from that of Al-based materials. A multi-phase bond profile was proposed and a multi-segmented bonding program was developed to enable parameter optimization at each stage of the bonding process to achieve a better bond quality. A stable process of >100,000 bonds was demonstrated in our lab.