Fine pitch copper wire bonding in high volume production

Abstract

Wire bonding is the predominant mode of interconnection in electronic packaging. Gold wire bonding has been refined again and again to retain control of interconnect technology due to its ease of workability and years of reliability data. Economic realities are now enabling fine diameter copper wire to compete with gold wire. It needs to be demonstrated however that known challenges in the assembly process and long term reliability can be managed successfully. Here, a rigorous methodology has been established to introduce copper wire bonding on new as well as converted dice into manufacturing. Manufacturing efficiencies and yields have been driven to be equivalent to gold wires. Reliability testing has passed the usual criteria and has been extended to demonstrate the viability of this technology. Interfacial analysis has confirmed the observations that intermetallic compounds form and grow slowly.