Method for improving specific volume of low voltage aluminum anode foil

Abstract

The invention provides a method for improving specific volume of a low voltage aluminum anode foil, being capable of reducing chloride ion content, reducing leakage current density and improving the specific volume of the aluminum anode foil. The method provided by the invention is mainly characterized in that: chloride ion in the aluminum anode foil is separated out more rapidly by utilizing electrochemical treatment in the initial period of formation and uniform and dense aluminum oxide crystal nucleuses are formed in an aluminum foil; concentration, temperature and exchange traffic of forming liquid as well as size of on load voltage and magnitude of current are adjusted, and corrosion reaction between residual chloride ion in the aluminum foil and the aluminum foil is reduced, thus the residual chloride ion is diffused into the forming liquid; meanwhile, plenty of aluminum oxide crystal nucleuses are formed in the aluminum foil, the crystal nucleuses grow continuously in a subsequent anode oxidation process, and content of crystal alumina in a dielectric layer is improved, thus the specific volume of the aluminum anode foil is improved. Compared with untreated aluminum anode foil, the specific volume of the aluminum foil can be improved by 3-20%, and leakage current density is reduced by 40-60%. The method provided by the invention can be directly applied to the current industrial large-scale production.

Description

technical field [0001] The invention belongs to the technical field of electronic materials, and in particular relates to a method for increasing the specific capacity of an anode aluminum foil used in a low-voltage aluminum electrolytic capacitor. Background technique [0002] Alumina is the working medium of aluminum electrolytic capacitors and the core of aluminum electrolytic capacitors. The quality of its film layer determines many properties of aluminum electrolytic capacitors, such as leakage current, loss, life, capacitance, etc. Therefore, researchers have been continuously studying the formation process of alumina from theory and practice, so that the quality of alumina film has been continuously improved. Ions make it difficult to guarantee the performance of the aluminum oxide film formed by anodic oxidation, while the crystalline aluminum oxide film is beneficial to improve the performance of aluminum electrolytic capacitors. [0003] In recent years, with the ...

AI Technical Summary

Problems solved by technology

[0004] However, as the specific capacity of the anode aluminum foil is required to be higher and higher, the thickness of the aluminum foil used is getting thicker and the degree of corrosion is getting higher and higher. The corrosion holes are getting deeper and more complex in shape. It also becomes smaller and smaller, making it difficult to clean the etchant chloride ions in the corrosion holes thoroughly, and a large amount of chloride ions remain inside, which increases the difficulty of subsequent anodic oxidation of aluminum foil, resulting in a decrease in the performance of the oxide film

[0005] At present, the cleaning process for residual chloride ions generally follows the aluminum foil corrosion process, and the method used is mostly nitric acid method. The removal of residual chloride ions is rarely considered during the formation of aluminum foil, which reduces the anode aluminum foil to a considerable extent. specific capacity, increasing its leakage current density