Copper Alloy Wire Selection Methodology for High Reliability Automotive IC packages

The role of Cu Alloy wire type in wire bonding as high-performance wire for automotive has not been clearly understood. As well as the criticality ultra-fine pitch application (<60umBPP) with Cu wire bonding as difficulty to pass and achieve a good humidity test reliability for packages with Al bond pad, which has no capability to convert with noble metal bonding pad surface. With ST experience of proper optimization and characterization for wire bonding process adding altogether into the process of wire type material selections has been put into a methodology. To select the best wire material to meet the robust solution for high reliability automotive requirement to match its compatibility, and to meet the target of high reliability requirement of automotive ultra fine pitch IC packages. The methodologies used are the understanding how to achieve robust intermetallic coverage, 1st bonding concept approach, and new corrosion characterization are the techniques that have been used in this experiment. This paper will show the selection of wire between 99.99% Cu wire (4N Cu wire) production and 99% Cu wire (Cu Alloy) types used in this experiment justify the wire compatibility vs. ST products. And after completion of this development this methodology was found to be the best approach to deploy to all other packing as it has consistent and robust response in manufacturing with no complaint about any reliability failures.