Three years of fine Cu wire bonding in high volume manufacturing

The rapid ramping of fine pitch copper wire bonding production is a perfect example of a market driven technology implementation. The explosive increase in gold commodity pricing has paved the road for this conversion. Several challenges known from thick copper wire bonding had to be overcome to make this technology viable technically and economically. Some fundamental studies of copper wire bonding to the full spectrum of die surfaces and wafer nodes was available at the beginning of manufacturing implementation but over the last year, a large number of research papers have been published greatly enhancing the basic understanding of mechanism, metallurgy and chemistry of copper wire bonding. Equipment manufacturers have developed dedicated copper wire bonders and tool kits, wire manufacturers have developed softer copper wires as well as oxidation resistant wires, mold compound suppliers have developed low corrosion compounds and wire bond engineers have learned to optimize the bonding process to yield cost effective and reliable copper wire bond die packages. Here, high volume manufacturing experiences of copper wire bond packaging and long term reliability data will be presented.