Thermosonic gold-wire bonding to precious-metal-free copper leadframes

The consistency and quality of Au wire thermosonically wedge-bonded to copper-alloy leadframes plated with pure copper is investigated, and its bondability is compared to that of the Au/Ag and Au/Au bonds. The considerations required to achieve successful bonds are also described. Special emphasis is given to the importance of the surface finish of the Cu-plated leadframes, and the die-attach and wire-bonding conditions required in order to make a highly reliable and cost-effective package. Results of the reliability tests of the packages assembled using Au-wire-to-Cu plated leadframes are discussed and compared with the package reliability results for the standard Au/Ag and Au/Au bonding processes