The manufacturing process flow for the aluminum electrolytic capacitors is as follows:
The anode foil, cathode foil, and electrolyte paper are cut to the specified width from the source rolls of the specified length.
Leads for contacting the cathode and anode foil electrodes are attached either by crimping or by ultrasonic welding.
The electrolytic paper is layered between the anode foil and the electrode foil. A coiled construction separates the electrodes. When the structure is coiled in this manner it is known as an "element."
The element is filled with the electrolyte using, for example, the vacuum method.
The rubber plug is attached to the filled element. Then, the element is placed in the case.
The case is slipped into a sleeve printed with the rated voltage, capacitance, and polarity. After which, the sleeve is heat shrunk on to the case.
The specified voltage is applied to grow an anode oxide thin film on the cut surface end and on any flaws in the formed oxide thin film.
All units are subjected to functional testing and cosmetic inspection. Non-conforming units are removed from production.