Influence of heat treatment process on leakage current of anodic aluminum oxide films

Nowadays, aluminum electrolytic capacitors have been extensively used due to their high specific capacitance, wide operating voltage range, and low cost. Anodic aluminum oxide films obtained by anodization of aluminum serve as the dielectric in an aluminum electrolytic capacitor, which primarily determine the performances of the aluminum electrolytic capacitors. The leakage current through the anodic aluminum oxide films is a key performance criterion for the capacitors. A lower leakage current means the excellent insulating property of the films. In this work, we investigated the influence of the heat treatment process at different temperatures on the leakage currents of anodic aluminum oxide films. FESEM and XRD results demonstrated that the morphology of anodic aluminum oxide film and the grain orientation of the aluminum substrate change after heat treatment. The aluminum grain orientation in the substrate can result in variations in the structure of the anodic film and its interfacial contact with the substrate, thereby changing the leakage currents. The leakage current of the anodic aluminum oxide films subjected to heat treatment at 110 °C is lower than those at other temperatures and has the best insulating performance.