An innovative annealing-twinned Ag-Au-Pd bonding wire for IC and LED packaging

An innovative annealing twinned Ag-(8-30%)Au-(0.01-6%) Pd wire for IC and LED packaging has been developed. It exhibits high thermal stability during aging at 600°C and a small heat affected zone after wire bonding. The mean failure time of this annealing twinned Ag-Au-Pd wire when stressed with a current density of 1.23 × 10⁵A/cm² is about double that of the conventional grained Ag-alloy wire. For packaging on Si chips with Al pads, it possesses sufficient intermetallic compounds at the initial as-bonded stage but a slow growth rate during further reliability tests. The excellent reliability of this new bonding wire has been verified in a DDRII BGA IC package and a 0605 LED package. In the LED package, this Ag-alloy wire provides the extra benefit of increasing the light output power (LOP) by about 3.2%.