JP5025287B2 - Aluminum electrolytic capacitor - Google Patents

Description

  The present invention relates to an aluminum electrolytic capacitor. In particular, it relates to a lead lead tab for an aluminum electrolytic capacitor.

Conventionally, an aluminum electrolytic capacitor has been stored in a case with a sealing plate together with an electrolytic solution as a capacitor element by laminating or winding aluminum foil as an anode and a cathode through a separator. To pull out the electrode from the capacitor element, one end of a lead lead tab made of aluminum foil is connected to the anode and the cathode, and the other end of the lead lead tab is connected to an external terminal provided on the sealing plate. It was.
Since the lead lead tab is located in the space between the capacitor element and the sealing plate, the lead wire tab is exposed to halogen such as chlorine that has been deteriorated from the electrolyte solution or from the capacitor member due to long-term use. It may end up.
In order to prevent this corrosion disconnection, conventionally, a method of coating the surface of the lead tab with a thermoplastic resin such as polypropylene resin, polyethylene resin, polyethylene terephthalate resin, or polyvinylidene fluoride resin (Patent Document 1), silicone resin, urethane resin, A method of coating an epoxy resin or the like on the surface of the lead tab (Patent Document 2) and a method of coating the surface of the lead tab with a melamine resin after curing (Patent Document 3) are disclosed.
JP-A-3-261125 Japanese Utility Model Publication No. 7-27143 JP 2006-120808 A

  The problem to be solved is that the lead-out lead tab foil is exposed to halogen such as chlorine that is washed away from the electrolyte and the deterioration of the electrolytic solution due to long-term use of the capacitor. In order to prevent this corrosion disconnection, resin may be coated on the surface of the lead tab. However, it is difficult to coat the resin at the corners and sides of the foil because of the resin pinholes that are likely to occur when coated. There were limits.

The present invention provides a capacitor element having a strip-shaped aluminum lead-out tab, a case having an opening for accommodating the capacitor element, a sealing plate for sealing the opening, and a sealing plate provided on the sealing plate, in the case. and an external terminal connected to the drawer lead tab, the aluminum electrolytic capacitor having, on the external terminal of the case inner surface side of the sealing plate, the size protrude from the connecting point of the said external terminal the extraction lead tab, the sacrificial metal An aluminum electrolytic capacitor characterized by being provided is provided.
The present invention also provides a capacitor element having a strip-shaped aluminum lead lead tab, a case having an opening for accommodating the capacitor element, a sealing plate for sealing the opening, and a sealing plate provided on the sealing plate. In the aluminum electrolytic capacitor having an external terminal connected to the lead lead tab, the sacrificial metal, then the porous sheet, and then the lead lead tab are laminated and fixed from the inside to the case inner surface side of the external terminal. Or providing an aluminum electrolytic capacitor characterized in that a sacrificial metal wrapped in a porous sheet and then a lead-out lead tab are laminated and fixed in this order on the inner surface side of the external terminal from the inside. is there.
Another object of the present invention is to provide the above aluminum electrolytic capacitor characterized in that aluminum containing more dissimilar metals than the lead lead tab is used as the sacrificial metal.
Another object of the present invention is to provide the above aluminum electrolytic capacitor characterized in that magnesium or an alloy thereof is used as the sacrificial metal.

The lead lead tab of the present invention is provided with a sacrificial metal on the external terminal on the inner surface side of the case of the sealing plate, so that the sacrificial metal can be easily installed. Even when exposed to halogen such as chlorine, there is an advantage that corrosion disconnection is suppressed or prevented.
In the lead lead tab of the present invention, the sacrificial metal is first provided from the inside on the case inner surface side of the external terminal of the sealing plate, so that the sacrificial metal can be easily installed. There is an advantage that it does not get in the way of deformation.
Also, if the sacrificial metal is sandwiched between the porous sheet and the sealing plate, or if it is wrapped in the porous sheet, it will prevent contact with the counter electrode and the metal case, and it will be porous even if the sacrificial metal partially falls off. There is an advantage that it is easy to hold in the quality sheet.
In addition, when aluminum containing more dissimilar metals such as copper, zinc and iron than the lead lead tab is used as the sacrificial metal, the aluminum in the sacrificial metal preferentially melts as ions. There is the advantage that there is little worry of contamination by.
In addition, when magnesium or an alloy thereof is used as the sacrificial metal, magnesium in the sacrificial metal is more likely to be dissolved out as ions than aluminum, so that it is possible to effectively suppress or prevent corrosion disconnection of the lead lead tab of aluminum. There is.

The external terminal described in the present invention is a terminal penetrating the sealing plate on the sealing plate of the capacitor case, and electrically connects the lead lead tab and the external circuit. The external terminal is generally formed in a substantially cylindrical shape, and a ridge is formed in the middle of the outer surface, and the ridge portion is embedded in the sealing plate. In general, a screw terminal having a screw hole is formed on the outer end face of the external terminal. At the other end of the external terminal, a connecting portion is provided by a riveting portion or an ultrasonic welding method for connecting and fixing the lead lead tab. Riveting is generally performed by providing a cylindrical portion that is thinner than the diameter of the external terminal, making a hole in the end portion of the lead tab and inserting it into the cylindrical portion, and then inserting a flat washer and caulking mechanically.
In the case of a sealing plate in which an insulating plate and a rubber plate are pasted together, the external terminal consists of a rivet and a metal plate terminal attached to it, and the other end is connected to and fixed to a lead lead tab. Generally, riveting is performed by making a hole in the end of the lead tab and inserting it into the cylindrical portion, then inserting a flat washer and caulking mechanically.

  The lead lead tab described in the present invention is a strip of 99.95% or more high-purity aluminum foil having a thickness of about 50 μm to 500 μm, and is not subjected to roughening such as etching. Plain foil is used. As the lead-out lead tab on the anode side, anodized one is also used. The lower ends of these terminals are electrically connected to the anode foil or the cathode foil. The electrical connection with the anode foil or the cathode foil is made by caulking or welding in a state where the anode lead lead tab and the cathode lead lead tab are overlapped on the surfaces of the anode foil and the cathode foil.

The sacrificial metal described in the present invention is made of aluminum containing more dissimilar metals than the lead lead tab, magnesium, or an alloy thereof, and has a shape of foil, sheet, plate, etc., metal crystal, amorphous, or sintered body ( Powder metallurgy). A composite material such as a clad material can also be used. These are appropriately selected depending on the usage environment of the capacitor. For handling, it is preferable to provide it as parallel as possible to the inner surface of the sealing plate.
Specifically, as aluminum containing a large amount of different metals, different metals such as copper, zinc, iron, lead, nickel, etc. are several tens to several hundreds as impurity components of aluminum having a purity of about 99.8%. In addition to those containing about 10 to several hundred ppm, other than conventional alloys with a maximum of several percent of copper, manganese, silicon, magnesium, zinc, etc. added to aluminum, iron, nickel, etc. The added one can be used. In particular, the copper alloy is preferably one having aluminum clad on one side.
As the magnesium alloy, magnesium added with aluminum, zinc, manganese, zirconia, or a rare earth element can be used.
The porous sheet described in the present invention can be used without any particular limitation, such as paper, nonwoven fabric, woven fabric, glass paper, and polyolefin porous membrane.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 shows all or part of an aluminum electrolytic capacitor according to the present invention. FIG. 1A shows a cross section of an aluminum electrolytic capacitor. FIG.1 (b) has shown the bottom face of the sealing board of an aluminum electrolytic capacitor, and has shown the state which provided the sacrificial metal in the external terminal of the case inner surface side of the said sealing board.
The aluminum electrolytic capacitor according to the present invention is a capacitor element in which an electrode foil is cut to an appropriate width and then a lead lead tab 1 is connected and wound or laminated together with a separator such as paper in the same manner as a normal aluminum electrolytic capacitor. 2 is housed in a case 3 made of a metal material such as aluminum having an upper surface opened and formed in a cylindrical shape or an elliptical cylindrical shape, and sealed with a sealing plate 4. Case 3 may be covered with an insulating tube.
The sealing plate 4 seals the opening on the upper surface of the case, and is made of an insulating resin such as polypropylene, polyphenylene sulfide, or phenol, and has a thickness of about 3 to 50 mm. It is placed on a protrusion provided on the inner peripheral surface in the vicinity of the case, and a stepped triangular protrusion is provided on the outermost periphery of the sealing plate, and an elastic body made of an elastic material such as rubber may be disposed. . The elastic body is inserted with the bent tip of the case by curling to improve the sealing performance. The external terminal 5 is set in advance in a molding die, and is molded by an insert resin mold or the like, and is integrally molded. The lead lead tab 1 is pulled out from the capacitor element 2 and connected and fixed on the inner surface side of the case 3 of the external terminal 5.
In many cases, the sealing plate is provided with a pressure valve or the like for releasing the pressure when the pressure inside the case rises. Moreover, it is preferable to provide partitioning projections 6 for separating the cathode and the anode on the inner surface of the sealing plate.
In FIG. 1A, a cylindrical portion that is thinner than the diameter of the external terminal 5 is provided inside the case of the external terminal 5, and first, the sacrificial metal 7 is inserted into the cylindrical portion of the external terminal on the anode side, and is porous. Insert the sheet 8 or reinforcing plate as necessary, then make a hole in the end of the drawer lead tab 1 and insert it into the cylindrical part of both external terminals 5, and finally insert a flat washer 9 Shows riveting. The diameter of the cylindrical portion of the external terminal on the anode side may be the same for the sacrificial metal portion and the lead lead tab portion, but the sacrificial metal 7 portion is more stable so that the lead lead tab is more stably connected to the external terminal. It is preferable that the portion of the lead lead tab is narrowed and the lead lead tab is fixed at the level difference.

FIG. 2 shows a lead lead tab and a sacrificial metal portion of an aluminum electrolytic capacitor according to the present invention.
The sacrificial metal 7 is wrapped in a porous sheet 8 and connected to the external terminal 5 together with the lead lead tab 1. Examples of the wrapping shape include a bag-like shape, a shape in which one side of a rectangle is folded, a shape in which two sides are folded, and a shape in which four sides of a ten o'clock shape are folded.

The lead tab of the capacitor element is made of aluminum foil having a thickness of 100 μm and a purity of 99.99% (impurities of 11 ppm of iron, 10 ppm of silicon, 50 ppm of copper, and 1 ppm or less). A plain foil with no plating was used, and the lead-out lead on the anode side was also subjected to anodization and provided in the capacitor element.
In the case inner part of the external terminal provided on the sealing plate with the external terminal, which is insert-molded with a phenol resin molding material containing a filler, a cylindrical part thinner than the diameter of the external terminal is provided. No. Insert a sacrificial metal sheet having a thickness of 300 μm from 1 to 10 into the above cylindrical portion of the external terminal on the anode side, and then insert a kraft paper having a thickness of 200 μm to hide the sacrificial metal sheet, Next, a hole was made in the end portion of the lead lead tab, inserted into the cylindrical portion of both external terminals, and finally a flat washer was inserted, and riveting was performed by mechanical caulking.
Next, the capacitor element was placed in an outer case together with the electrolytic solution, and sealed with a sealing plate.
When the surface condition of the lead lead tab after observing the applied lead voltage tab surface at 1000 ° C. for 1000 hours at an applied voltage of 650 V was observed, no erosion marks could be confirmed with the sacrificial metal sheet provided, but the sacrificial metal sheet was not attached. The one was corroded.

The whole or a part of the aluminum electrolytic capacitor according to the present invention is shown. 3 shows a lead lead tab and a sacrificial metal portion of an aluminum electrolytic capacitor according to the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Lead lead tab, 2 ... Capacitor element, 3 ... Case, 4 ... Sealing board, 5 ... External terminal, 6 ... Partitioning protrusion, 7 ... Sacrificial metal, 8 ... Porous sheet, 9 ... Flat washer.

Claims (4)

A capacitor element having a strip-shaped aluminum lead lead tab, a case having an opening for storing the capacitor element, a sealing plate for sealing the opening, and provided in the sealing plate and connected to the lead lead tab in the case in an aluminum electrolytic capacitor having an external terminal, a to, to the external terminal of the case inner surface side of the sealing plate, the size protruding from the connection portion between said external terminal the extraction lead tab, in that a sacrificial metal Features an aluminum electrolytic capacitor.   A capacitor element having a strip-shaped aluminum lead lead tab, a case having an opening for storing the capacitor element, a sealing plate for sealing the opening, and provided in the sealing plate and connected to the lead lead tab in the case In the aluminum electrolytic capacitor having the external terminal, the inner surface of the external terminal is fixed to the inner surface of the case from the inside, in the order of the sacrificial metal, then the porous sheet, and then the lead-out lead tab. An aluminum electrolytic capacitor characterized in that a sacrificial metal wrapped in a porous sheet and then a lead-out lead tab are laminated and fixed in this order on the inner surface side of the case from the inside.   3. The aluminum electrolytic capacitor according to claim 1, wherein aluminum containing a larger amount of a different metal than the lead lead tab is used as the sacrificial metal.   The aluminum electrolytic capacitor according to claim 1 or 2, wherein magnesium or an alloy thereof is used as the sacrificial metal.

Images