How copper wire material additive elements effect the reliability of wire bonded contacts in HAST testing

During the past ten years, copper (Cu) bond wires have increasingly replaced gold (Au) wire materials. While this development began in the consumer electronics sector, Cu wires are now increasingly advancing into applications with challenging environmental conditions and high reliability requirements, such as the automotive sector. In the meantime, several types of high reliability Cu wires are available in the market. However, there are only few papers describing/comparing the effect of the additive element used in the Cu bulk material. Thus, we investigated the failure and improving mechanisms of Cu wire bond contacts with different type of additive elements. Subsequent to the challenging artifact-free preparation routines, high resolution analyses (SEM, transmission electron microscopy - TEM, nanospot-EDS) were carried out on ball bond contacts to clarify the effect of additive elements to the reliability of the wire bonded contacts especially during HAST. The result s of this investigation will be valuable information for the wire users in selecting the optimal wire material required for automotive devices.