High Capacitance Aluminum Matrix Composite Dielectric Film Preparation Techniques

Aluminum electrolytic capacitors play the indispensable role in electronic circuit due to their particular performance. In order to satisfy the high integrated requirements of electronic equipment, aluminum electrolytic capacitors are developing towards smaller volume, higher capacitance and lower cost. Anode aluminum foil is the key material for manufacturing aluminum electrolytic capacitors, and the size and application of aluminum electrolytic capacitors strongly depend on the properties of the anodic oxide film formed on which. Studies on the manufacture of high-capacitance anodic oxide film used for low-voltage aluminum electrolytic capacitor are essential in this dissertation, and the specific capacitance of aluminum foil was increased through three technologies.We introduced the progress of the research methods to improve the specific capatance firstly. Then discribed the preparation of Al₂O₃-Nb₂O₅,Al₂O₃-BST and Al₂O₃-BT composite oxide films in detail. The structure and composition of these composite oxide films were analysised by SEM,XPS and XRD methods.The important results and innovations are as follows:1. The Al₂O₃-Nb₂O₅ composite oxide films with high dieletric constant were prepared by complexation precipitation and anodizing. The complexation precipitation process,the technical conditions for preparing Nb₂O₅ coating layer and the anodic oxide process were discussed. Under the optimum conditions, the specific capacitance of aluminum foil is increased in ratio of 28%. XPS and XRD results show that there is Nb₂O₅ in the composite structure.2. Al₂O₃-BST and Al₂O₃-BT composite oxide films were prepared by Sol-gel method. Discussed the process of high dielectric phase BST and BT precipitation on the surface of aluminum etched foils and the anodic oxide process in detail. Under the optimum conditions, the specific capacitance of Al₂O₃-BST composite oxide films is increased in ratio of 26% at 50Vf, the specific capacitance of Al₂O₃-BT composite oxide films is increased in ratio of 26.7% at 20Vf. XPS and XRD results show that there are BST and BT phases in the composite structure.