An evaluation of the feasibility of copper ball‐wedge bonding on Au, Cu thick film and aluminium metallisations was carried out. This evaluation is not merely a check for feasibility, but will also give more insight into the problems concerning copper ball‐wedge bonding. This article does not pretend to represent profound research on copper ball bonding, but will give qualitative insight. Copper ball bonding, without using cover gas, is possible, but the bond quality decreases. Extrusion and penetration of the ball bond in the substrates are caused by the hardness of the copper. This can only be avoided when the hardness of the substrate is matched to the hardness of the copper ball/wire. Bonding mechanisms are similar for bonding on thick film to those for bonding on metallisations. Matching hardness of the substrate to the ball/wire seems to be a necessity for proper ball‐wedge bonding.
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