Wire bonding optimization with fine copper wire for volume production

Abstract

The adoption of copper wire in high volume wire bonding production has proven successful as seen in the tremendous increase in copper wire consumption in the past year. This increase largely came from the conversion from gold to copper wire in fine pitch devices which previously had been more conservative due to concerns related to copper wire reliability. Fine pitch applications with bond pad openings of 45um and less using 0.8mil and less wire diameter require more stringent control on bonding qualities. Specially designed copper hardware that maintains an oxygen free environment, as well as more elaborate wire bonding processes were required to meet the challenges in copper wire bonding, some with success but often with compromises to production throughput and mean-time-between-assist (MTBA).