Electrolytic capacitor with improved connection part

A method to manufacture an electrolytic capacitor, the method comprising:

• providing a can having an opening;
• providing a capacitor element;
• providing a covering element to close the opening of the can, the covering element having an inner surface directed to an inside of the can and an opposite outer surface directed to an outside of the can when closing the can;
• providing a connection element for externally applying an electrical signal to the capacitor element,
• wherein the connection element comprises an external terminal for applying the electrical signal and a lead tab for applying the electrical signal to the capacitor element and a rivet having a first and a second head,
• wherein the rivet penetrates the covering element so that the first head of the rivet protrudes out of the covering element at the inner surface of the covering element and the second head of the rivet protrudes out of the covering element at the outer surface of the covering element,
• wherein the rivet is configured such that the first head of the rivet fixes the lead tab to the covering element at the inner surface of the covering element and the second head of the rivet fixes the terminal to the covering element at the outer surface of the covering element,
• wherein the connection element comprises an upper washer and a lower washer respectively having an opening to receive the rivet,
• wherein the upper washer is placed between the lead tab and the first head of the rivet and the lower washer is placed between the lead tab and the inner surface of the covering element,
• wherein the upper washer is formed having a first surface directed to the inside of the can, a second surface being located opposite to the first surface and directed to the inner surface of the covering element and a third surface laterally located between the first and the second surface of the upper washer, and
• wherein the upper washer is configured such that the third surface is formed with a taper such that the second surface of the upper washer has a larger area than the first surface of the upper washer;
• providing a press machine to fix the terminal and the lead tab at the covering element by a riveting process, wherein the press machine comprises an outer jig to fix the upper washer and an inner jig to crash the rivet and to form the first head of the rivet, and wherein the outer jig comprises one of a tapered surface or rollers to be pressed to the third surface of the upper washer during the riveting process;
• inserting the capacitor element into the opening of the can;
• and
• closing the opening of the can by the covering element.

An electrolytic capacitor comprising:

• a can having an opening;
• a capacitor element being housed by the can;
• a covering element configured to close the opening of the can, the covering element having an inner surface directed to an inside of the can and an opposite outer surface directed to an outside of the can;
• and
• a connection element configured to externally apply an electrical signal to the capacitor element,
• wherein the connection element comprises an external terminal configured to externally apply the electrical signal and a lead tab being electrically coupled to the capacitor element and the external terminal,
• wherein the connection element comprises a rivet having a first and a second head,
• wherein the rivet penetrates the covering element so that the first head of the rivet protrudes out of the covering element at the inner surface of the covering element and the second head of the rivet protrudes out of the covering element at the outer surface of the covering element,
• wherein the rivet is configured such that the first head of the rivet fixes the lead tab to the covering element at the inner surface of the covering element and the second head of the rivet fixes the external terminal to the covering element at the outer surface of the covering element,
• wherein the connection element comprises an upper washer and a lower washer respectively having an opening, to receive the rivet,
• wherein the upper washer is placed between the lead tab and the first head of the rivet, the lower washer being placed between the lead tab and the inner surface of the covering element,
• wherein the upper washer has a first surface directed to the inside of the can, a second surface being located opposite to the first surface and directed to the inner surface of the covering element and a third surface laterally located between the first and second surfaces of the upper washer,
• wherein the upper washer is configured such that either the first surface of the upper washer comprises a cavity to receive the first head of the rivet or the second surface of the upper washer comprises a protrusion or the third surface of the upper washer has a taper such that the second surface has a larger area than the first surface of the upper washer,
• wherein the opening of the upper washer extends from the first surface of the upper washer to the second surface of the upper washer, and
• wherein the lead tab extends along the second surface of the upper washer and along a side wall of the opening of the upper washer and along the first surface of the upper washer.