Relationship between Trace Mn and the Pitting Behavior of Aluminum Foil Used for High Voltage Electrolytic Capacitors

The effect of Mn addition in aluminum anode foils for high voltage electrolytic capacitors on the pitting behavior as well as the properties of the etched foils was studied. The Mn distribution in the aluminum foils which are processed with the same rolling and annealing condition was characterized by secondary ion mass spectrometer (SIMS). The results show that the distribution of Mn along the depth of the foil varies with the addition of Mn, while the volume fraction of the cube texture keeps stable. The SIMS results also show that the segregation tendency of Mn onto the foil surface becomes stronger with the increasing of Mn content. The square corrosion pits on the foils with higher Mn content after etching on the same condition are denser and more homogeneous. Also, the specific capacitance of the etched foils after forming at 520 V increases with the increase of Mn content in the range from 2.3 μg/g to 14.7 μg/g.