JP5978605B2 - Capacitor manufacturing method - Google Patents

Description

The present invention relates to a method of manufacturing a capacitor such as an electrolytic capacitor, an electric double layer capacitor which is connected to the electrode foil the lead terminals by cold pressure welding method.

  Various capacitors such as electrolytic capacitors have lead terminals connected to electrode foils on the anode side and cathode side of the capacitor element. The capacitor element is wound with a separator interposed between the anode-side and cathode-side electrode foils. The capacitor element is impregnated with an electrolytic solution and then enclosed in an outer case. As the anode foil and the cathode foil, a foil formed of an electrode material such as aluminum is used. The anode foil is subjected to surface expansion treatment and chemical conversion treatment by etching on the foil surface. The cathode foil is subjected to surface expansion treatment and chemical conversion treatment as necessary.

  As a method for connecting the electrode foil and the lead terminal, there is a cold welding method. This pressure welding method is a method of connecting an electrode foil and a lead terminal by pressing a metal mold at a connecting portion. A mold having a trapezoidal pressing surface has been used for this pressing (for example, Patent Document 1 and Patent Document 2).

JP 7-235453 A JP 2007-273645 A

  By the way, it is known that the oxide film formed on the surface of the electrode foil by chemical conversion treatment is generally hard and brittle. In addition, capacitors are required to be smaller and have higher capacity. In increasing the capacity, an electrode foil that has been subjected to a high-magnification etching process to increase the surface area of the electrode foil is used. The remaining core portion of the electrode foil that has been subjected to this high magnification etching (the portion where the oxide film has not been formed) is thinner than the electrode foil that has not been subjected to the high magnification etching. For this reason, the electrode foil which performed the high magnification etching process and performed the chemical conversion process is weakened. When such an electrode foil is pressed with a cold pressure welding die, there is a problem that a part of the electrode foil is cracked or the reliability of connection is lowered.

  Further, in the miniaturized capacitor, since the width of the electrode foil is narrow, the distance between the connection portion with the lead terminal and the edge of the electrode foil is short. Cracks generated in the electrode foil at the connection portion reach the edge of the electrode foil, and this causes cracking of the foil. Such cracks and cracks in the electrode foil have a problem of deteriorating the connectivity with the lead terminal.

  Such cracks and foil cracks in the electrode foil are related to the shape of the pressing surface on which the cold pressure welding mold is pressed against the electrode foil. Conventionally, the pressing surface has a rectangular shape, and the cross-sectional shape has a trapezoidal shape. When a cold pressure welding die having such a shape is used, stress at the time of pressing is concentrated on the corner of the pressing surface. This stress concentration causes excessive stress from the corner portion of the pressing surface to the pressing portion of the electrode foil. In the electrode foil weakened by high-magnification etching or the like, there is a problem that the stress cannot be overcome and causes cracks.

The purpose of the capacitor fabrication method of the present invention has been made in view of the above problems, to prevent damage to the electrode foil, such as cracks or foil cracks due to cold weld connection, to increase the connection strength between the electrode foil and the lead terminal is there.

To achieve the above object, a manufacturing method of the capacitor of the present invention is as follows.

(1) In order to achieve the above object, the method for producing a capacitor of the present invention is a method for producing a capacitor in which an electrode foil and a lead terminal are connected by a cold pressure welding method, wherein the pressing portion of the cold pressure welding die is The cross-sectional shape is spherical and the planar shape is circular, the electrode foil used for the anode side electrode or cathode side electrode of the capacitor element is overlaid on the lead terminal, and a deformation prevention stopper is provided as a restraining standing wall on the side of the lead terminal. And pressurizing the extraction terminal in a space formed by the deformation prevention stopper and the extraction terminal, and pressing the cold pressure welding mold to the connection portion between the electrode foil and the extraction terminal, Connect the drawer terminal.

  According to the present invention, the following effects can be obtained.

  (1) Since the pressing surface of the cold pressure welding mold is circular and does not have a corner, local stress concentration on the electrode foil can be avoided, so that cracking and cracking of the electrode foil can be prevented.

  (2) The connectivity between the electrode foil and the lead terminal can be improved and the connection strength can be improved.

Other objects, features, and advantages of the present invention will become clearer with reference to the accompanying drawings and each embodiment.

It is a figure which shows the connection part of the electrode foil which concerns on 1st Embodiment, and an extraction terminal. It is sectional drawing which shows the IIA-IIA line cross section of FIG. It is a figure which shows the connection process of electrode foil and an extraction terminal. It is sectional drawing which shows the cold pressing metal mold | die which concerns on 2nd Embodiment, and a connection process. It is a figure which shows the modification of the connection process which used the constraining metal mold | die which concerns on 3rd Embodiment together. It is a figure which shows the modification which used the fixing jig together with the restraint metal mold | die.

[First Embodiment]

  FIG. 1 shows a connection portion between an electrode foil and a lead terminal according to the first embodiment. The configuration shown in FIG. 1 is an example, and the present invention is not limited to such a configuration.

  The electrode foil 2 is used as an anode side electrode or a cathode side electrode of a capacitor element. The electrode foil 2 is made of aluminum, for example. In the electrolytic capacitor, a metal foil obtained by subjecting the anode foil to a surface enlargement treatment by etching is further used, and a metal foil obtained by subjecting the cathode foil to a surface enlargement treatment by etching is used.

  The lead terminal 4 connected to the electrode foil 2 includes, as an example, an internal lead part 4-1, a support part 4-2, and an external lead part 4-3. The internal lead portion 4-1 is a flat portion obtained by compression-molding an aluminum rod-shaped body. The support part 4-2 is a prototype part of the above-described rod-shaped body in which the internal lead part 4-1 is not formed, and is passed through a sealing member of an outer case housing a capacitor element (not shown) and supported by the sealing member. It is a part to be made. The external lead portion 4-3 is thinner than the support portion 4-2, and is formed of a wire whose surface is plated with a solderable metal. The external lead part 4-3 is connected to the support part 4-2 by welding. The external lead portion 4-3 may be formed of a solderable metal wire.

  The lead terminal 4 is pressure-welded to the electrode foil 2 superimposed on the internal lead portion 4-1 by a cold pressure welding method. A plurality of connecting portions 6-1 and 6-2 are formed between the lead terminal 4 and the electrode foil 2. Each of the connecting portions 6-1 and 6-2 is a curved concave portion 8 having a circular shape in plan view. The curved recess 8 is an example of a recess having a circular planar shape. The curved concave portion 8 is a trace of the press contact connection generated in the electrode foil 2 and the extraction terminal 4 by pressing of the cold press contact mold 10 (FIG. 3).

  FIG. 2A shows a cross section of each of the connection portions 6-1 and 6-2. B of FIG. 2 shows an enlarged cross section of the IIB portion of A of FIG.

  As shown in FIG. 2A, each connection portion 6-1 and 6-2 is formed with a curved concave portion 8 having a hemispherical cross section. At the bottom of each curved recess 8, a connection is made between the electrode foil 2 and the internal lead part 4-1 of the lead terminal 4 by pressure contact. In this embodiment, as shown in FIG. 2B, the electrode foil 2 faces the curved recess 8, and the internal lead part 4-1 is crushed together with the stacked electrode foil 2. In the part shown with a broken line, the metal of the electrode foil 2 and the internal lead part 4-1 is integrated.

  FIG. 3 shows a connection process by a cold pressure welding method. This connection step is one step included in the method for manufacturing a capacitor. This embodiment is an example of a method for manufacturing a capacitor in which an electrode foil and a lead terminal are connected by a cold welding method. FIG. 3A shows a state before pressure contact. FIG. 3B shows the pressure contact process.

  This connection process includes an overlap process and a pressure contact process.

  (1) Overlay process

  In this stacking step, the electrode foil 2 is stacked on the upper surface of the internal lead portion 4-1 of the lead terminal 4 placed on the upper surface of the flat surface mold 12. In this case, a cold pressure welding die 10 having a spherical pressing surface 14 is used. The center of the lead terminal 4 is aligned with the center line O of the cold pressure welding die 10. The lead terminal 4 and the electrode foil 2 superimposed are held in place.

  (2) Pressure welding process

  Through the above-described overlapping process, the cold pressure welding die 10 is lowered onto the upper surface of the electrode foil 2 superimposed on the extraction terminal 4. As a result, the electrode foil 2 and the internal lead part 4-1 of the lead terminal 4 are sandwiched between the cold pressure welding mold 10 and the flat surface mold 12. A pressure P toward the flat surface mold 12 is applied to the cold pressure welding mold 10. As a result, as shown in FIG. 3B, the spherical pressing surface 14 of the cold welding die 10 is formed on the connection portions 6-1 and 6-2 of the internal lead portion 4-1 of the electrode foil 2 and the lead terminal 4. A curved concave portion 8 is formed. As a result, the electrode foil 2 and the metal of the internal lead part 4-1 of the extraction terminal 4 are connected by being integrated.

  When the cold pressure welding die 10 having such a spherical pressing surface 14 is used, the following pressure welding connection is obtained.

  (a) Since the electrode foil 2 is pressed by the spherical pressing surface 14, the stress applied to the electrode foil 2 from the spherical pressing surface 14 acts radially from the spherical pressing surface 14, resulting in uniform stress and avoiding stress concentration it can. That is, since the spherical pressing surface 14 has no corners, there is no stress concentration generated in the corners in the conventional mold. The spherical pressing surface 14 can prevent stress from the cold pressure welding mold 10 from being concentrated at a specific location. For this reason, even if the electrode foil 2 is weakened, since there is no local concentration of stress, the generation of cracks due to the stress concentration can be prevented.

  (b) The electrode foil 2 pressed by the spherical pressing surface 14 and the pressure contact portion between the lead terminal 4 and the flat internal lead portion 4-1 are expanded. As a result, the area of the connection parts 6-1 and 6-2 is large, and the connection strength between the electrode foil 2 and the lead terminal 4 can be increased.

  [Second Embodiment]

  While the cold pressure welding mold 10 according to the first embodiment has a spherical pressing surface 14, the second embodiment uses a cold pressure welding mold 10 with a truncated cone-shaped pressing surface 16. ing. FIG. 4 shows a cold pressure welding die 10 having a truncated conical pressing surface 16 and a pressure welding connection according to the second embodiment using the same. 4, the same parts as those in FIG. 3 are denoted by the same reference numerals.

  In the second embodiment, the cold pressure welding die 10 is provided with a truncated cone-shaped pressing surface 16 as shown in FIG. The frustoconical pressing surface 16 has a curved surface portion 16-connecting the flat surface portion 16-1 and the conical surface portion 16-2 together with the flat surface portion 16-1 and the conical surface portion 16-2 at the distal end portion of the cold pressure welding die 10. 3 is provided.

  If the cold pressure welding die 10 provided with such a truncated conical pressing surface 16 is used, the curved concave portion 8 of the cold pressure welding die 10 is formed by the truncated conical pressing surface 16 as shown in FIG. 4B. The That is, in the curved concave portion 8 formed in the connection portions 6-1 and 6-2, the flat surface portion 18-1 is formed in the electrode foil 2 and the internal lead portion 4-1. A mortar-shaped conical surface portion 18-2 is formed around the flat surface portion 18-1. A continuous surface portion is formed by the curved surface portion 18-3 between the conical surface portion 18-2 and the flat surface portion 18-1.

  For this reason, the following press contact connection is obtained also in the second embodiment.

  (a) Since the electrode foil 2 is pressed by the truncated cone-shaped pressing surface 16, the stress applied to the electrode foil 2 from the truncated cone-shaped pressing surface 16 acts radially from the truncated cone-shaped pressing surface 16. In other words, since there is no corner in the truncated cone-shaped pressing surface 16, there is no stress concentration generated in the corner in the conventional mold. The frustum-shaped pressing surface 16 can prevent stress from the cold pressure welding mold 10 from being concentrated at a specific location. For this reason, even if the electrode foil 2 is weakened, as in the first embodiment, since there is no local concentration of stress, cracking due to stress concentration can be prevented.

  (b) As in the first embodiment, the electrode foil 2 pressed by the frustoconical pressing surface 16 and the contact portion between the lead terminal 4 and the flat internal lead portion 4-1 are expanded. As a result, the area of the connection parts 6-1 and 6-2 is large, and the connection strength between the electrode foil 2 and the lead terminal 4 can be increased.

[Other Embodiments]

  (1) In order to suppress deformation of the internal lead part 4-1 of the lead terminal 4 in the flat surface mold 12 of the above embodiment, a constraining mold 20 may be used. In this constraining mold 20, a deformation preventing stopper 20-2 is provided as a constraining standing wall on the side of the flat surface portion 20-1 parallel to the flat surface of the flat surface mold 12, and each deformation preventing stopper 20-2 and the flat surface portion 20. The internal lead portion 4-1 may be pressurized in the space formed by -1. If it is set as such a structure, the foil crack by the stress deformation of the drawer terminal 4 can be prevented, and the connection strength of the connection parts 6-1 and 6-2 can be raised more.

  In other words, if the constraining die 20 is disposed, when the cold pressure welding die 10 is pressed, the extension of the lead terminal 4 in the width direction can be prevented, thereby preventing the electrode foil 2 from being stretched and the remaining core of the electrode foil 2 can be prevented. The elongation of the portion can be prevented, and the thickness of the electrode foil 2 can be prevented from being reduced. As a result, there is no expansion of the lead terminal 4 in the width direction when pressed, and cracking of the foil due to stress deformation of the lead terminal 4 can be prevented, and the connection strength of the connection portions 6-1 and 6-2 can be further increased.

  Furthermore, as shown in FIG. 6 when pressed against the electrode foil 2 side, the fixing jig 22 may be arranged so as to sandwich the electrode foil 2 with the deformation prevention stopper 20-2. With such a configuration, the drawing terminal 4 is restrained by the restraining die 20 when the cold pressure welding die 10 is pressed, and the force with which the drawing terminal 4 extends upward by the fixing jig 22 can be suppressed. As a result, the deformation of the lead terminal 4 and the extension of the electrode foil 2 can be prevented, so that the pressing force can be concentrated on the connection portions 6-1 and 6-2, and the connection strength of each connection portion 6-1 and 6-2. Is further enhanced.

  (2) In the above embodiment, the electrode foil of the electrolytic capacitor has been exemplified. However, the electrode foil other than the electrolytic capacitor may be used for pressure contact connection between the lead terminal.

As described above, the most preferable embodiment and the like of the present invention have been described. However, the present invention is not limited to the above description, and is described in the claims or a form for carrying out the invention. It goes without saying that various modifications and changes can be made by those skilled in the art based on the gist of the invention disclosed in the above, and such modifications and changes are included in the scope of the present invention.

In the present invention, the pressing surface portion of the cold pressure welding mold is formed into a spherical shape or a truncated cone shape, so that the electrode foil can be protected from the stress concentration generated at the time of pressing, cracks due to pressure welding and foil cracking can be prevented, and a highly reliable capacitor Contributes to provision and is useful.

2 Electrode foil 4 Lead terminal 4-1 Internal lead part 4-2 Support part 4-3 External lead part 6-1 Connection part 6-2 Connection part 8 Curved concave part 10 Cold pressure contact mold 12 Flat surface mold 14 Spherical shape Pressure surface 16 Frustum-shaped pressure surface 16-1 Flat surface portion 16-2 Conical surface portion 16-3 Curved surface portion 18-1 Flat surface portion 18-2 Conical surface portion 18-3 Curved surface portion 20 Restraint mold 20-1 Flat surface portion 20-2 Deformation prevention stopper 22 Fixing jig

Claims (1)

A method of manufacturing a capacitor in which an electrode foil and a lead terminal are connected by a cold welding method,
The pressing part of the cold pressure welding mold is formed into a spherical cross section and a circular planar shape,
Overlay the electrode foil used for the anode side electrode or cathode side electrode of the capacitor element on the lead terminal,
Provided with a deformation prevention stopper as a restraining standing wall on the side of the extraction terminal, pressurizing the extraction terminal in a space formed by the deformation prevention stopper and the extraction terminal,
Connecting the electrode foil and the extraction terminal by pressing the cold pressure welding mold to the connection portion between the electrode foil and the extraction terminal;
Capacitor manufacturing method.

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