Nano-Composite Barrier Anodic Aluminum Oxide for ICD Capacitors

摘要

Anodizing of aluminum in acid solutions has been widely used to produce nano-porous coatings on aluminum for architectural or decorative purposes. This amorphous oxide can be grown electrolytically to thicknesses of many microns with a relatively well organized array of nano-pores extending nearly down to the metal surface. Aluminum oxide for normal electrolytic capacitor applications is produced by different formation processes without the use of prior anodization. However, this nano-crystalline oxide forms in the tensile stress state which can lead to localized ruptures within the dielectric film. Present work shows that by adding a hydrothermal treatment between the anodization and the barrier layer formation step, one can produce a nano-composite barrier layer while maintaining an amorphous oxide layer adjacent to the metal. It is expected that this structure will offer the low stress, high stability of amorphous oxide while maintaining high capacitance typical of nano-crystalline oxide.