Ultrasonic wire bonding of aluminum wire has been carried out onto gold and chromium surfaces using K&S wedge wire bonder (Model: 4523). Three distinct settings, power, time, and force were varied to find and propose the optimal process parameters for strong mechanical and electrical bond between the Al wire and the Cr and Au surfaces. It turned out that the range of optimal process windows for bonding onto a Cr surface is much smaller than bonding onto an Au surface. The range of power, time, and force for Cr are 3.0 - 3.5, 3.0 - 5.0, and 2.0 - 3.0 ± 1.0, respectively. To the contrary, the range of power, time, and force for Au are 2.5 - 4.0, 4.0 - 5.0 ± 1.0, and 3.0 - 4.0 ± 1.0, respectively.