Anodization of aluminum electrolyte capacitor foil

摘要

In order to increase the crystalline oxide content of barrier layer oxide and hence its capacitance, aluminum electrolytic capacitor foil is anodized at an average current density of at most 3 mA/cm2 of effective surface area in an aqueous electrolyte of C4 to C7 unsubstituted aliphatic dicarboxylic acid containing 0 to 0.05 wt. % of citric acid or tartaric acid and preferably at a temperature above 70 DEG C. The anodized foil is subjected to a relaxation and reanodization treatment to stabilize the foil. The anodization at low current density promotes high crystalline oxide content of the barrier layer oxide, and the relaxation and reanodization insure a stable barrier layer oxide of increased capacitance.