Mechanism of the Electromigration in Ag-Pd Alloy Bonding Wires

The failure mechanism of the electromigration in Ag-Pd bonding wires was investigated through stressing with a current density of 1.23 × 105 A/cm2 at temperatures of 150 °C to 300 °C. It was found that the grains of the wire materials grew rapidly during current stressing for 100 minutes at various temperatures. In contrast, the grain structure remained almost unchanged after storage at these temperatures for 100 minutes without current stressing. The mean-time-to-failure (MTF) for various current-stressed Ag-Pd alloy wires decreased with increases in Pd content. The activation energy for the electromigration of these wire materials was measured, and the results indicated that the main driving force was surface diffusion of Ag.