Electrolytic capacitor "ESR", by a capacitive reactance "X" and by an inductive reactance "X" (Inductance) formula_4. Then "Z" is given by Electrolytic capacitor An electrolytic capacitor (abbreviated e-cap) is a polarized capacitor whose anode or positive plate is made of a metal that forms an insulating oxide layer through anodization. This oxide layer acts as the dielectric of the capacitor. A solid, liquid, or gel electrolyte covers the surface of this oxide layer, serving as the (cathode) or negative plate of the capacitor. Due to their very thin dielectric oxide layer and enlarged anode surface, electrolytic capacitors have a much higher capacitance-voltage
Aluminum electrolytic capacitor for better self-healing property of the oxide layer, so that the capacitors have the advantages of both low ESR and low leakage current. The basic material of the anode for aluminum electrolytic capacitors is a foil with a thickness of ~ 20–100 µm made of aluminum with a high purity of at least 99.99%. This is etched (roughened) in an electrochemical process to increase the effective electrode surface. By etching the surface of the anode, depending on the required rated voltage, the surface area can be increased by a factor of approximately 200 with respect to a smooth surface. After