Copper wire bond on MCM device (bond stitch on bump ball)

Copper wire bonding is becoming popular on multi chip (MCM) device in parallel with the general industry trend of integrating more functions into single product. In order to support device to device interconnect; bond stitch on ball (BSOB) bonding method is quite generally used in the industry. However, copper wire due to its material hardness is more difficult to be manufactured into BSOB as compared to gold wire. In this paper, key challenges for copper wire bond BSOB and its solutions are discussed. Problem solving methodology including copper material selection, bonding tool (capillary) design, bonding concept and special wire bond software features will be explored to develop robust process window for copper wire bonding with good reliability and production worthy.