JP2009290059A - Method of manufacturing electrolytic capacitor, and electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an electrolytic capacitor that improves the productivity by decreasing the frequency of replacement of a projection pattern for joining electrode foils and tab terminals together and also improves the yield by maintaining peeling strength even when the frequency of replacement is decreased to avoid foil breaking. <P>SOLUTION: The method of manufacturing the electrolytic capacitor 30 by superposing the electrode foils 38 and 39 and tab terminals 40 and 41 between the projection mold 50 having a projection portion 52 and a flat mold 51 disposed opposite the projection portion 52, and joining the electrode foils 38 and 39 and tab terminals 40 and 41 together by cold pressure bonding by placing the projection mold 50 or flat mold 51 in relative contacting/leaving motion uses the projection mold 50 such that an outer wall surface of the projection portion 52 pressing the electrode foils 38 and 39 and tab terminals 40 and 41 has a tilt angle of 40 to 50°. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrolytic capacitor in which an electrode foil and a tab terminal are joined by a joint formed by cold pressure bonding, and a manufacturing method for producing such an electrolytic capacitor.

  In an electrolytic capacitor, a capacitor element formed by winding a separator paper between an anode foil and a cathode foil (hereinafter sometimes collectively referred to as an electrode foil) is housed in a case. Configured. An anode terminal and a cathode terminal connected to the anode foil and the cathode foil of the capacitor element respectively protrude from the sealing body that seals the opening of the case.

  The surfaces of the anode foil and the cathode foil are etched for a surface expansion treatment for increasing the surface area. By performing the etching, the surface of each electrode foil is roughened and widened, and the capacitance of the capacitor can be increased.

  Each tab foil connected to each of the anode terminal and the cathode terminal is attached to each electrode foil subjected to the surface enlargement treatment. Each tab terminal is generally fixed by cold pressing (cold weld method) (see, for example, Patent Document 1 and Patent Document 2).

Here, the structure of the conventional convex type and flat type used for the cold press which joins a tab terminal to electrode foil as disclosed by patent document 1 is shown in FIG.
The tab terminal 2 and the electrode foil 1 are overlapped, and the convex mold 4 is disposed on the electrode foil 1 side. Further, a flat mold 9 is arranged on the tab terminal 2 side so as to face the convex mold 4. A plurality of convex portions 5 are formed on the convex mold 4, and each convex portion 5 presses the electrode foil 1 and the tab terminal 2 from the electrode foil 1 side to form the joint portion 7.

  The convex portion 5 is formed as an inclined surface 11 in which the opposing surfaces of the convex portions 5 are inclined by a predetermined angle. A shear surface 12 that is substantially perpendicular to the tab terminal 2 and the electrode foil 1 is formed on the surface of the convex portion 5 opposite to the inclined surface 11.

  In Patent Document 1, by lowering the convex mold 4, the electrode foil 1 is sheared in the stacking direction by the shear surface 12 of the convex portion 5 to form the sheared portion 8, and the inclined surface of the convex portion 5 is formed. 11 discloses that the electrode foil 1 and the tab terminal 2 flow due to plastic deformation, and the joint portion 7 is formed by the tip surface 6 of the convex portion 5.

JP 2007-273645 A Registered Utility Model No. 3136629

When designing an electrolytic capacitor, an electrode foil is selected according to the purpose of use of the electrolytic capacitor and required performance. One of the parameters for selecting the electrode foil is the thickness of the electrode foil.
On the other hand, when the electrode foil and the tab terminal are bonded, it is necessary to bond them well so as to have a sufficient bonding strength and not to cause a foil breakage or the like. The foil breakage refers to a phenomenon in which the foil becomes extremely thin at the joint and causes a break. As described above, when joining the electrode foil and the tab terminal, an appropriate convexity is considered in consideration of the thickness of the electrode foil, the hardness of the electrode foil (toughness, brittleness), the degree of surface expansion treatment of the electrode foil, and the like. You must choose a type.

  As described above, when the conventional electrolytic capacitor is manufactured, it is necessary to replace the convex mold every time the manufactured product is changed. If the convex mold is replaced every time the product to be manufactured is changed, there is a problem that the work of replacing the convex mold, positioning the convex mold, adjusting the press pressure, and the like are required, and the productivity of the electrolytic capacitor is reduced.

  In addition, even if the product to be manufactured is changed, if the same convex mold is used without changing the convex mold, the manufactured electrolytic capacitor cannot obtain a sufficient bonding strength and the foil breaks. There is also a problem that the yield of electrolytic capacitors may decrease due to problems such as these.

  In general, the thickness of the cathode foil and that of the anode foil are different. For example, the thickness of the cathode foil used for the same electrolytic capacitor may be 20 μm, and the thickness of the anode foil may be 100 μm. As described above, since the cathode foil is generally thinner than the anode foil, the cathode foil is likely to break the foil when joined to the tab terminal.

  In particular, in order to prevent the foil from being cut simply in the cathode foil, it is conceivable to reduce the press pressure. However, if the press pressure is weakened, the peel strength from the tab terminal cannot be maintained even if the foil does not break.

Furthermore, as described above, the thickness of the electrode foil varies depending on the type of electrolytic capacitor. Speaking of the cathode foil, the thickness varies from about 15 to 60 μm.
For such cathode foils with various thicknesses, there has been a search for a convex type that does not cause foil breakage and can maintain the peel strength with the tab terminal even if the replacement frequency is reduced. ing.

  Therefore, the present invention has been made to solve the above-described problems, and the object of the present invention is to reduce the frequency of replacement of the convex type for joining the electrode foil and the tab terminal even when manufacturing various electrolytic capacitors. An object of the present invention is to provide an electrolytic capacitor manufacturing method capable of improving the yield by improving the productivity and maintaining the peel strength and preventing the occurrence of foil breakage even when the replacement frequency is reduced. .

According to the electrolytic capacitor manufacturing method of the present invention, the electrode foil and the tab terminal are arranged so as to overlap each other between the convex type having the convex part and the flat type arranged facing the convex part. In the manufacturing method of manufacturing the electrolytic capacitor by joining the electrode foil and the tab terminal by cold pressing by relatively moving the convex or flat mold, the convex mold, It is characterized by using the electrode foil and the inclination angle of the outer wall surface of the convex portion that presses the tab terminal is 40 ° to 50 °.
By adopting this method, even when various electrolytic capacitors are manufactured, it is possible to maintain a sufficient peel strength without inconvenience such as foil breakage without replacing the convex mold each time. This can save productivity and increase productivity and contribute to improving yield. The tab terminal of the present invention is formed in a foil shape.

  Moreover, it is good also using the thing whose inclination | tilt angle of the outer wall surface of the said convex part is 45 degrees. According to this method, there is no defect such as a foil breakage, and the peel strength can be improved.

Furthermore, the said convex part is good also as a square shape when planarly viewed.
According to this method, it is possible to prevent the convex mold from adhering to the electrode foil and the tab terminal, to improve the releasability and to prevent the foil from being cut.

Furthermore, the said convex type is arrange | positioned at the said electrode foil side, and may press the electrode foil and tab terminal which were piled up from the electrode foil side.
According to this method, it is possible to increase the peel strength and to improve the releasability.

  The convex shape may be a convex shape for a cathode for joining a cathode foil and a cathode tab terminal.

  According to the electrolytic capacitor in accordance with the present invention, in the electrolytic capacitor in which the electrode foil and the tab terminal are joined by the joint formed by cold crimping, the inclination angle of the inner wall surface of the recess formed in the joint is 40 ° to 50 °.

Further, the inclination angle of the inner wall surface of the recess formed in the joint may be 45 °.
Furthermore, the concave portion of the joint portion may have a square shape in plan view.

The concave portion of the joint portion may be formed so as to be recessed from the cathode foil toward the cathode tab terminal.
The junction may be a cathode junction formed by cold-pressing a cathode foil and a cathode tab terminal.

According to the electrolytic capacitor manufacturing method of the present invention, even when various electrolytic capacitors are manufactured, productivity is improved by reducing the frequency of replacement of the convex shape for joining the electrode foil and the tab terminal, and Even if the replacement frequency is reduced, the yield can be improved by maintaining the peel strength and preventing the foil from being cut.
According to the electrolytic capacitor of the present invention, the foil does not break and the peel strength can be improved.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.
FIG. 1 shows the overall configuration of the electrolytic capacitor of this embodiment.
In the electrolytic capacitor 30 of this embodiment, a capacitor element 32 is disposed inside a bottomed cylindrical outer case 31 formed of a metal such as aluminum, and the opening of the outer case 31 is sealed with a rubber-laminated laminated resin plate or the like. The body 34 is closed.
The outer case 31 is covered with a sleeve 35 on which a performance indication of the capacitor is printed.

FIG. 2 shows the structure of the capacitor element.
The capacitor element 32 is configured by winding an anode foil 38, a cathode foil 39, and a separator paper 37 impregnated with an electrolytic solution, disposed between the anode foil 38 and the cathode foil 39.

  Anode terminal 42 and cathode terminal 43 are connected to anode foil 38 and cathode foil 39 via anode tab terminal 40 and cathode tab terminal 41, respectively. The anode terminal 42 and the cathode terminal 43 are disposed so as to protrude from the opening of the outer case 31.

As the anode foil 38, an aluminum foil whose surface has been enlarged by etching is used. Further, the etched anode foil 38 is further subjected to a chemical conversion treatment to form an oxide film on the surface subjected to the surface expansion treatment.
Similarly to the anode foil 38, the cathode foil 39 is made of an aluminum foil that has been subjected to a surface expansion treatment by etching, but the surface that has been subjected to the surface expansion treatment need not be subjected to a chemical conversion treatment to form an oxide film.

The anode tab terminal 40 fixed to the anode foil 38 is made of an aluminum plate material. As the anode tab terminal 40, an aluminum plate material subjected to surface enlargement by etching may be used. However, the etched anode tab terminal 40 is subjected to a chemical conversion treatment to form an oxide film on the surface subjected to the surface expansion treatment.
The cathode tab terminal 41 fixed to the cathode foil 39 is also made of an aluminum plate. The cathode tab terminal 41 may also be made of an aluminum plate whose surface has been enlarged by etching. However, the etched cathode tab terminal 41 need not be subjected to chemical conversion to form an oxide film.

A structure for attaching the cathode tab terminal 41 to the cathode foil 39 in this embodiment will be described with reference to FIG.
The cathode tab terminal 41 and the cathode foil 39 are attached by a joint 44 formed by cold pressure bonding. The joining portions 44 are formed at a plurality of locations, and are joined using a convex mold having a plurality of convex portions as will be described later. At the joint portion 44, the cathode tab terminal 41 and the cathode foil 39 are joined in a pressure-bonded state.

A method of attaching the cathode tab terminal to the cathode foil will be described with reference to FIG.
As described above, the cathode tab terminal 41 and the cathode foil 39 are attached by cold pressure bonding. In the cold press bonding, the cathode convex mold 50 and the cathode flat mold 51 provided in a not-shown pressing device are relatively moved toward and away from each other, and the stacked cathode tab terminal 41 and the cathode foil 39 are connected to the cathode. This is performed by pressing with a convex mold 50 and a flat cathode 51 for cathode.

In the present embodiment, the cathode convex mold 50 is disposed below and the cathode flat mold 51 is disposed above, and the cathode convex mold 50 is raised relative to the cathode flat mold 51 to perform press working. The
In the present embodiment, only one cathode convex portion 52 is formed on the cathode convex mold 50, but a plurality of cathode convex portions 52 are formed on one cathode convex mold 50. It is good to have.
In the present invention, the cathode convex mold 50 is disposed below and the cathode flat mold 51 is disposed above, and the cathode convex mold 50 is raised with respect to the cathode flat mold 51. For example, the cathode convex mold 50 may be disposed on the upper side and the cathode flat mold 51 may be disposed on the lower side, or the cathode flat mold 51 may be moved up or down with respect to the cathode convex mold 50. Good.

The cathode convex portion 52 may be one having an inclination angle α of the outer wall surface 52b of 40 ° to 50 °. In particular, the inclination angle α is preferably 45 °. In this way, foil breakage is prevented, and the cathode foil 39 and the cathode tab terminal 41 can be applied to the cathode foil 39 having various thicknesses while maintaining a predetermined peel strength. it can.
The inclination angle α of the cathode convex portion 52 is an angle formed by the outer wall surface (inclined surface) 52b of the cathode convex portion 52 and the base surface 52c of the cathode convex portion 52.

FIG. 5 shows a plan view of the cathode convex portion.
The top 52a of the cathode convex portion 52 is formed in a planar shape.
Moreover, the convex part 52 for cathodes is formed in the square shape when planarly viewed. Specifically, it is good to form in a square. In this way, by forming the cathode convex portion 52 in a square shape in plan view, it is possible to prevent the cathode convex portion 52 from sticking to the cathode foil 39 and the cathode tab terminal 41 after pressing, and to improve the releasability. In addition, the foil can be prevented from being cut.

Between the cathode convex mold 50 and the cathode flat mold 51, the cathode foil 39 and the cathode tab terminal 41 are arranged so that the cathode tab terminal 41 is superimposed on the cathode foil 39.
Thus, in the present embodiment, the cathode convex mold 50, the cathode foil 39, the cathode tab terminal 41, and the cathode flat mold 51 are arranged in this order from the bottom. Then, when the cathode convex mold 50 is raised, the cathode convex portion 52 presses the cathode foil 39 toward the cathode tab terminal 41 to cold-compress the cathode foil 39 and the cathode tab terminal 41. Thus, when the convex part 52 for cathodes presses the cathode foil 39 to the tab terminal 41 side for cathodes, it can raise peeling strength and can also make the mold release property at the time of manufacture favorable.

FIG. 6 shows a cross-sectional shape of a joint formed using such a convex mold.
In the present embodiment, the joining portion 44 is formed by the cathode convex portion 52 being formed by pressing the cathode foil 39 toward the cathode tab terminal 41 side, and therefore is recessed from the cathode foil 39 side toward the cathode tab terminal 41 side. A recess 55 is formed. The inclination angle α of the recess 55 (the angle formed by the inner wall surface 55a of the recess 55 and the surface of the cathode foil 39) is 40 ° to 50 °. In particular, the inclination angle α is preferably 45 °.

  Thus, when the inclination angle α of the concave portion 55 of the joint portion 44 is 40 ° to 50 °, particularly 45 °, there is no foil breakage, and the electrolytic capacitor can maintain the peel strength at a predetermined value or more. can do.

  The inclination angle of the convex part of the cathode convex part for joining the cathode foil and the cathode tab terminal is changed to 38 °, 40 °, 45 °, 50 °, 52 °, 60 °, and the thickness is 20 μm (for high voltage) ), 30 μm (for low voltage), 40 μm (for low voltage), 50 μm (for low voltage), 4 types of cathode foils are bonded to the cathode tab terminal, and each foil is checked for appearance (A), peeling Evaluation was performed based on strength measurement (B) and releasability (C). In addition, the press pressure of the press apparatus at this time is 1.5 Mpa.

(A) The appearance inspection is performed with a stereomicroscope 20 times or more for cracking or cutting of the foil.
(B) The peel strength is measured by fixing the cathode foil, applying a force to pull the joined cathode tab terminal in the vertical direction, and measuring the peeled force with a push-pull gauge. When the force at this time is larger than a predetermined value, it is determined as a non-defective product.
(C) Whether the releasability is good or not is determined by performing an appearance inspection with a stereomicroscope 20 times or more for the presence or absence of foil breakage resulting from poor releasability.

The results are shown in Table 1. In Table 1, evaluation is made with ○, Δ, and ×, but as described above, the three evaluations of appearance inspection (A), peel strength measurement (B), and releasability (C) are comprehensively viewed. I am evaluating.
In particular,
○: (A), (B), (C) are all good.
(Triangle | delta): There exists an indication of a crack and a piece of electrode foil. However, the acceptable range for the product. Moreover, there is difficulty in releasability. Therefore, the productivity is affected.
X: The electrode foil has cracks / cuts.

  According to the experimental results as described above, when the inclination angle of the convex portion for the cathode is in the range of 40 ° to 50 °, it can be produced as a product for various types of cathode foils. In particular, in the case of 45 °, almost no defective product was generated, and the product was able to be produced satisfactorily, and a very favorable result was obtained.

  In the above-described embodiment, only the inclination angle of the convex portion in the convex shape for the cathode that joins the cathode foil and the cathode tab terminal has been described. However, in the present invention, the anode foil that joins the anode foil and the anode tab terminal is described. The inclination angle of the convex portion in the convex shape can also be adapted.

  While the present invention has been described above with reference to a preferred embodiment, the present invention is not limited to this embodiment, and it goes without saying that many modifications can be made without departing from the spirit of the invention. .

It is sectional drawing from the side of the electrolytic capacitor concerning this invention. It is a perspective view of a capacitor element. It is explanatory drawing which shows the attachment structure of the tab terminal for cathodes, and cathode foil. It is a side view which shows the convex type for cathodes and the flat type for cathodes used for cold press bonding. It is a top view of the convex type for cathodes. It is sectional drawing of the junction part after cold-bonding cathode foil and the tab terminal for cathodes. It is explanatory drawing which shows the mode of joining of the conventional electrode foil and a tab terminal.

Explanation of symbols

30 Electrolytic Capacitor 31 Exterior Case 32 Capacitor Element 34 Sealing Body 35 Sleeve 37 Separator Paper 38 Anode Foil 39 Cathode Foil 40 Anode Tab Terminal 41 Cathode Tab Terminal 42 Anode Terminal 43 Cathode Terminal 44 Joint 50 Cathode Convex 52 Convex part 51 Flat type for cathode 55 Concave part

Claims (10)

Between the convex mold having the convex portion and the flat mold arranged opposite to the convex portion, the electrode foil and the tab terminal are arranged to overlap each other,
In the manufacturing method of manufacturing the electrolytic capacitor by joining the electrode foil and the tab terminal by cold pressure bonding by relatively moving the convex type or the flat type.
A method for producing an electrolytic capacitor, characterized in that the convex shape has an inclination angle of an outer wall surface of a convex portion pressing the electrode foil and the tab terminal of 40 ° to 50 °.   2. The method of manufacturing an electrolytic capacitor according to claim 1, wherein an inclination angle of the outer wall surface of the convex portion is 45 degrees.   The method for manufacturing an electrolytic capacitor according to claim 1, wherein the convex portion has a square shape when seen in a plan view.   The said convex type is arrange | positioned at the said electrode foil side, and presses the electrode foil and tab terminal which were piled up from the electrode foil side, The any one of Claims 1-3 characterized by the above-mentioned. Manufacturing method of the electrolytic capacitor.   5. The method for manufacturing an electrolytic capacitor according to claim 1, wherein the convex shape is a convex shape for a cathode for joining a cathode foil and a tab terminal for a cathode. 6. . In an electrolytic capacitor in which an electrode foil and a tab terminal are joined by a joint formed by cold pressure bonding,
The electrolytic capacitor according to claim 1, wherein an inclination angle of an inner wall surface of the concave portion formed in the joint portion is 40 ° to 50 °.   The electrolytic capacitor according to claim 6, wherein an inclination angle of an inner wall surface of the concave portion formed in the joint portion is 45 °.   The electrolytic capacitor according to claim 6 or 7, wherein the concave portion of the joint portion has a square shape when seen in a plan view.   9. The electrolytic capacitor according to claim 6, wherein the concave portion of the joint portion is formed so as to be recessed from the cathode foil toward the cathode tab terminal.   The electrolysis according to any one of claims 6 to 9, wherein the joint is a cathode joint formed by cold-pressing a cathode foil and a cathode tab terminal. Capacitor.

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