High performance Ag-Pd alloy wires for high frequency IC packages

Binary Ag-Pd alloy wires designed for both requirements of high reliability and low electrical resistivity have been developed and patented by Wire Technology Co. in Taiwan. The electrical resistivity of these Ag-Pd bonding wires are 1.98 to 3.5μΩ·cm. After stressing with various current densities, their mean times to failure are much higher than those of Au wire and Pd coated Cu wire. For the wire bonding of IC packages using these Ag-Pd binary alloy wires with forming gas, the units per hour (UPH) are similar to those using Au wire and better than those using Pd coated wire. In addition, these Ag-Pd alloy wires show sufficient intermetallic layers at the initial as-bonded stage on Al pads but slow growth rates during further aging at 150°C. The Au wire bonded interfaces reveal an overgrowth of intermetallic compounds in contrast to the diminutive intermetallics growth in Cu-wire bonded packages. The high reliability of such Ag-Pd wire-bonded IC products has been verified in a high frequency DDR III package.