Fusing current of short aluminum bond wire

An analytical and experimental study of steady-state fusing current of unencapsulated aluminum wirebonds was performed, in order to confirm existing analytical work with more extensive experimental data. Finite element modeling results and experimental data were compared for wire heated by constant current, with wire lengths of 30-150 mils and diameters of 0.8-1.25 mils. Die temperatures were also varied from 30-100/spl deg/C. Material properties for the model were taken from the SRC/CINDAS database for Al 1%Si. Very good agreement was obtained between the experimental data and the one-dimensional finite element conduction model. A semi-empirical model was also derived to include the second order effect of convective cooling of the wire. The effect of over-bonding was shown to be minimal as was the effect of die temperature, within the range tested. Little variation was found between replicates of test conditions which were conducted in random order. Finally, the effect of CMOS transistor operating frequency above 100 MHz on wire burn-out was considered briefly.