JP2012138400A - Method for manufacturing electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an electrolytic capacitor having a precise marking part.SOLUTION: A method for manufacturing an electrolytic capacitor of the present invention includes the steps of: containing a capacitor element in a metal case having an outside surface on which a resin film made of an epoxy resin or a polyethylene terephthalate resin is formed; and irradiating the metal case with a laser beam to form a marking part. In the step of forming the marking part, the marking part is formed by removing the resin film at a portion irradiated with the laser beam.

Description

  The present invention relates to a method for manufacturing an electrolytic capacitor.

  Generally, product information is displayed on an electronic component. For example, if a defect occurs in an electronic component, the distribution history can be tracked from the above product information, and other electronic components manufactured on the same line can be collected to prevent further occurrence of the defect. Can do.

  Also in the electrolytic capacitor, product information is displayed at a visible position. For example, in an electrolytic capacitor in which a capacitor element is housed in a metal case, the outer surface of the metal case is covered with nylon resin, and UV curable ink is printed on the nylon resin using a printing device. Is generally displayed. Since nylon resin has high extensibility, it is suitable for forming a metal case by coating a metal plate with nylon resin and molding it.

  However, the above printing method is difficult to adjust the position of the electrolytic capacitor, the printing adjustment, the density adjustment, etc. in the printing apparatus, resulting in printing misalignment, printing fading, etc., and it is difficult to mark product information accurately and clearly. There was a problem. Further, in the above electrolytic capacitor, in order to prevent printing peeling, it is necessary to clean the surface of the metal case before printing, and there is a problem that manufacturing cost and manufacturing tact are increased.

  Moreover, the electrolytic capacitor is miniaturized, and accordingly, the printing space is reduced. For this reason, the marking part which shows sufficient product information cannot be formed, and tracking of a distribution history may become difficult. In order to solve this problem, it is necessary to accurately display product information with smaller symbols, characters, etc., but there is a problem that it is difficult to form a precise marking portion by printing with UV curable ink.

  In view of the above circumstances, an object of the present invention is to provide a method for manufacturing an electrolytic capacitor having a precise marking portion.

  The present invention includes a step of housing a capacitor element in a metal case provided with an outer surface of a resin film made of epoxy resin or polyethylene terephthalate resin, and a step of irradiating the metal case with a laser to form a marking portion. In the step of forming the marking portion, the marking portion is formed by removing the portion of the resin film irradiated with the laser.

  In the above electrolytic capacitor manufacturing method, the marking portion includes a groove portion formed on the outer surface of the metal case by removing the resin film, the side surface of the groove portion is partitioned by the resin film, and the bottom surface of the groove portion is the resin. It is preferable that the outer surface of the metal case exposed by removing the film is partitioned.

  In the method for manufacturing an electrolytic capacitor, the groove width of the groove is preferably 100 μm or less.

  In the method for manufacturing an electrolytic capacitor, the marking portion preferably includes a bar code display.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the electrolytic capacitor which has a precise marking part can be provided.

It is sectional drawing which shows typically one Embodiment of an electrolytic capacitor. It is a figure which shows typically one Embodiment of a capacitor | condenser element. It is a figure which shows typically one Embodiment of the metal case provided with the resin film. It is a figure which shows typically one Embodiment of the state which accommodated the capacitor | condenser element in the metal case. In examination 2, it is a figure which shows the display of the marking part formed in the bottom face of an electrolytic capacitor.

  Hereinafter, embodiments of an electrolytic capacitor manufacturing method according to the present invention will be described with reference to the drawings. The following embodiments are merely examples, and various embodiments can be implemented within the scope of the present invention. In the drawings of the present invention, the same reference numerals represent the same or corresponding parts.

<Embodiment 1>
FIG. 1 is a cross-sectional view schematically showing one embodiment of the electrolytic capacitor manufactured in the present embodiment. In FIG. 1, a capacitor element 10 is accommodated in a metal case 11 provided on the outer surface with a resin film 16 made of epoxy resin or polyethylene terephthalate (hereinafter referred to as “PET”) resin. Moreover, the marking part is formed in the outer surface of the metal case 11 of an electrolytic capacitor, for example, the bottom face 11b.

  The electrolytic capacitor includes a step of housing the capacitor element 10 in the metal case 11 provided with the resin film 16 on the outer surface, and a step of irradiating the metal case 11 with a laser to form a marking portion. Can be manufactured by. Hereinafter, this manufacturing method will be described in detail with reference to FIGS.

(Preparation of capacitor element)
First, the capacitor element 10 shown in FIG. 2 is prepared. FIG. 2 shows a state before the outermost periphery of the wound body 20 is stopped.

  The manufacturing method of the capacitor element 10 is not particularly limited, and can be manufactured by a known method. Here, an example of a method for producing the capacitor element 10 including a conductive polymer layer as an electrolyte will be described, but an electrolytic solution may be included as an electrolyte.

  First, the anode body 21 on which the dielectric film is formed and the cathode body 22 are wound through the separator 23. At this time, by winding the lead tabs 15A and 15B while winding them, the lead tabs 15A and 15B can be erected in the wound body as shown in FIG.

  The anode body 21 and the cathode body 22 are each made of a metal foil. The kind of metal of the anode body 21 and the cathode body 22 is not specifically limited, For example, valve action metals, such as aluminum, a tantalum, niobium, can be used. The material of the separator 23 is not particularly limited, and for example, a nonwoven fabric mainly composed of synthetic cellulose, vinylon, or aramid fiber can be used. Moreover, the material of lead tab 15A, 15B is not specifically limited, What is necessary is just a material which can conduct electricity. The material of the lead wires 14A and 14B connected to each of the lead tabs 15A and 15B is not particularly limited as long as it can conduct electricity.

  Next, the winding tape 24 is disposed on the outer surface of the cathode body 22 located in the outermost layer among the wound anode body 21, cathode body 22 and separator 23, and the end of the cathode body 22 is fastened. Stopping with the tape 24, the wound body 20 is produced. Then, the capacitor element 10 is manufactured by forming a conductive polymer layer between the anode body 21 and the separator 23 and between the separator 23 and the cathode body 22. In addition, the formation method in particular of an electroconductive polymer layer is not restrict | limited, For example, it can form by the well-known chemical polymerization method or electrolytic polymerization method.

(Preparation of a metal case provided with a resin film)
Next, a metal case 11 having a resin film 16 made of epoxy resin or PET resin on the outer surface is prepared.

  As shown in FIG. 3, the metal case 11 is formed of a cylindrical body having an open top surface and a closed bottom surface, and a resin film 16 is provided on the outer surface of the cylindrical body. The metal case 11 provided with the resin film 16 may be formed by forming the resin film 16 on a metal plate and then forming the metal plate into a cylindrical body having a bottom surface, or the cylindrical metal case 11 having a bottom surface. After molding, the resin film 16 may be formed on the outer surface thereof. As a method for forming the resin film 16, for example, the resin constituting the resin film 16 may be applied to the outer surface of the metal case 11 and then cured, or the resin film 16 prepared in advance may be attached to the metal case 11. May be attached.

  The resin film 16 may be provided on the entire outer surface of the metal case 11, that is, on the entire bottom surface and the entire side surface, or may be provided on the entire bottom surface or part of the bottom surface. It may be provided in the part. At least in the step of forming a marking portion to be described later, the resin film 16 only needs to be provided at the laser irradiation position.

  The material of the metal case 11 is not particularly limited, and for example, aluminum, copper, iron, nickel, titanium, brass, and alloys thereof can be used. Aluminum is preferred because it is easy and inexpensive to form.

  The resin film 16 is made of epoxy resin or PET resin. The thickness of the resin film 16 is not particularly limited, but it is preferably thinner from the viewpoint that a miniaturized electrolytic capacitor is required. In particular, since the epoxy resin and the PET resin have high strength, the strength can be sufficiently maintained even when the thickness is 15 μm or less, further 6 μm or less. Further, since the thickness of the resin film 16 is thin, it is possible to reduce the time for laser irradiation in the step of forming a marking portion described later.

(Process for accommodating capacitor element)
Next, as shown in FIG. 4, the capacitor element 10 is accommodated in the metal case 11. In this step, for example, the capacitor element 10 can be accommodated in the metal case 11 by inserting the capacitor element 10 from the opening side of the metal case 11.

  Further, a sealing member 12 formed so that the lead wires 14A and 14B penetrate therethrough is placed on the upper surface of the capacitor element 10 accommodated in the metal case 11, and the vicinity of the opening end on the side surface of the metal case 11 is horizontally reduced. The metal case 11 having the shape shown in FIG. 1 can be manufactured by processing and curling. Furthermore, by installing the seat plate 13 above the curled metal case 11, the capacitor element 10 can be sealed in the metal case 11 as shown in FIG. Alternatively, the dielectric coating may be repaired by performing an aging process after sealing the capacitor element 10.

(Process to form marking part)
Next, the metal case 11 is irradiated with a laser to form a marking portion.

  Specifically, the resin film 16 provided on the outer surface of the metal case 11 is irradiated with a laser. The resin film 16 in the portion irradiated with the laser is gasified by heat, and thereby the resin film 16 in the portion irradiated with the laser is removed. In particular, since the thermal deformation temperature of the epoxy resin and the melting point of the PET resin are high, for example, the resin film 16 in the vicinity of the resin film 16 that is irradiated with the laser is prevented from being removed. And the portion irradiated with the laser can be precisely removed. Note that the wavelength, intensity, and the like of the laser can be changed as appropriate depending on the thickness of the resin film 16 and the type of resin constituting the resin film 16.

  Therefore, the marking part formed by this process includes a groove part formed by removing the resin film 16 from the outer surface of the metal case 11, and the side surface of the groove part is partitioned by the resin film 16, and the bottom surface of the groove part Is formed by the outer surface of the metal case 11 exposed by removing the resin film 16.

  The resin film 16 preferably has a color tone different from that of the metal case 11. In this case, since the color tone of the metal case 11 exposed by removing the resin film 16 and the resin film 16 are different, visual observation of the marking portion and reading by the device are facilitated. The surface of the resin film 16 may be colored, the resin layer 16 may be a plurality of layers, and the color of the surface layer may be different from the color of the metal case 11. Also in these cases, since the color tone of the metal case 11 exposed by removing the resin film 16 and the surface of the resin film 16 are different, visual observation of the marking portion and reading by the device are facilitated.

  Further, the outer surface of the metal case 11 exposed by removing the resin film 16 may be irradiated with laser. By irradiating the outer surface of the metal case 11 with a laser, the surface of the metal case 11 can be discolored. Therefore, for example, by making the color tone of the resin film 16 different from the color tone after the color change of the metal case 11, the difference between the portion where the resin film 16 is not removed and the portion where the resin film 16 is removed. Becomes clear and the discrimination of the marking portion is further improved.

  In addition, with reference to FIG. 4, the marking part may be formed in the side surface 11a of the metal case 11, and may be formed in the bottom face 11b. In particular, in the metal case 11 made of a cylindrical body having the bottom surface 11b, it is preferable that the bottom surface 11b is a flat surface and a marking portion is formed on the bottom surface 11b. By forming the marking portion on the bottom surface 11b, which is a flat surface, the discrimination of the marking portion is further improved.

  Through the above steps, the capacitor element 10, the metal case 11 that houses the capacitor element 10, the resin film 16 made of epoxy resin or PET resin provided on the outer surface of the metal case 11, and a part of the resin film 16 An electrolytic capacitor including a marking portion formed by irradiating a laser is manufactured.

  According to the first embodiment, since the thermal deformation temperature of the epoxy resin and the melting point of the PET resin are high, for example, the resin film 16 in the vicinity thereof is removed together with the resin film 16 in the laser irradiated portion. The portion irradiated with the laser can be accurately removed. For this reason, a precise marking part can be formed.

  Further, in the conventional method of printing UV curable ink on a nylon resin, it is necessary to change the mold required for printing whenever the lot number of the product changes. In addition, it is necessary to clean the surface of the metal case before printing. On the other hand, since the marking part formed in said embodiment can be made into a desired shape by scanning a laser, product information can be easily displayed by a marking part. Further, since the laser is irradiated, it is not necessary to clean the metal case as in the prior art. Therefore, according to the above method for manufacturing an electrolytic capacitor, the manufacturing cost and the manufacturing tact can be reduced as compared with the conventional method.

  Further, the inventor has found that a marking portion composed of a groove portion having a groove width of 100 μm or less can be formed by irradiating a laser to the epoxy resin and the PET resin, and further, 50 μm or more and 100 μm or less. It has been found that a marking portion having a groove width can be formed. Therefore, more product information can be displayed on the electrolytic capacitor, and the distribution history can be traced more easily.

  Further, according to the first embodiment, as described above, since a narrow groove portion having a groove width of 50 μm or more and 100 μm or less can be formed, for example, a barcode display is provided on the outer surface of the metal case 11. It becomes possible to display precisely.

<Embodiment 2>
In the first embodiment described above, after the capacitor element 10 is accommodated in the metal case 11, the marking portion is formed in the metal case 11. For example, the capacitor element 10 is accommodated in the metal case 11 in which the marking portion is formed. Also good.

  That is, in the second embodiment, the capacitor element 10 and the metal case 11 provided with the resin film 16 are prepared, and the marking portion is formed on the outer surface of the metal case 11 provided with the resin film 16. After the operation, the capacitor element 10 can be accommodated in the metal case 11.

  According to the second embodiment, since the thermal deformation temperature of the epoxy resin and the melting point of the PET resin are high as in the first embodiment, for example, the resin film 16 in the portion irradiated with the laser is positioned in the vicinity thereof. The portion of the resin film 16 to be removed can be prevented from being removed, and the portion irradiated with the laser can be precisely removed. For this reason, a precise marking part can be formed.

  Since the description other than the above in the second embodiment is the same as that in the first embodiment, the description thereof will not be repeated.

  The winding type electrolytic capacitor has been described above, but the electrolytic capacitor is not limited to this, and can be applied to any electrolytic capacitor manufacturing method as long as the capacitor element is accommodated in a metal case. it can.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Examination 1>
Example 1
In Example 1, a wound type electrolytic capacitor was produced. Below, the specific manufacturing method of an electrolytic capacitor is demonstrated.

(1) Preparation of Capacitor Element First, the surface of the aluminum foil was roughened by etching the aluminum foil, and then a dielectric coating was formed on the surface of the aluminum foil by chemical conversion treatment. And this aluminum foil was cut | judged so that length x width might become 6 mm x 100 mm, and the anode body was prepared.

  Next, a separator and a cathode body having the same area as the anode body were prepared, and the anode body and the cathode body were wound through the separator while a lead tab was wound. Next, the end of the outer surface of the wound body was stuck with a winding tape to produce a wound body. Aluminum foil was used as the cathode body, and a lead wire was connected to the end portion protruding from the wound body of the lead tab. Then, the produced wound body was subjected to a chemical conversion treatment again to form a dielectric film on the cut end portion of the anode body.

  Next, the conductive polymer layer made of polythiophene is formed by immersing the wound body in a polymerization solution containing 3,4-ethylenedioxythiophene and ferric p-toluenesulfonate, and heating it after lifting. Formed. A capacitor element was fabricated through the above steps.

(2) Preparation of metal case Next, as a metal case, an aluminum case having a cylindrical body having a bottom surface (see FIG. 3) was used, and a metal film provided with a resin film made of epoxy resin on the entire outer surface of the aluminum case. Prepared. The resin film was formed on the outer surface of the metal case by curing after application. The thickness of the resin film at this time was about 6 μm, and the thermal decomposition temperature of this epoxy resin was 270 degrees.

(3) Step of accommodating capacitor element And after accommodating the capacitor element in a metal case provided with a resin film, and further placing a rubber packing on the upper surface of the capacitor element on the opening side of the metal case The vicinity of the opening end of the side surface of the metal case was laterally drawn and curled. Then, a capacitor plate was sealed in the metal case by installing a seat plate above the curled metal case, and then subjected to an aging treatment.

(4) Step of forming marking portion Next, a laser beam was irradiated on the bottom surface of the metal case to form a marking portion including a bar code display indicating product information.

  Specifically, a YAG laser device (manufactured by SUNX, LP-F10R) is used against the bottom surface of the metal case for 0.5 seconds at a laser power of 100% so that the laser irradiation area matches the bar code display. Laser irradiation was performed. As a result, the resin film in the portion irradiated with the laser was removed, and the surface of the metal case exposed by removing the resin film was changed to black, thereby forming a marking portion composed of a bar code display. The thickness of each line constituting the bar code display was 70 μm, and the interval between the lines was 47 μm. Twenty electrolytic capacitors were manufactured through the above steps.

(Example 2)
Twenty electrolytic capacitors were manufactured in the same manner as in Example 1 except that a resin film made of PET resin was provided on the outer surface of the metal case. At this time, the thickness of the resin film was about 15 μm, and the thermal decomposition temperature of this PET resin was 265 degrees.

(Comparative Example 1)
Twenty electrolytic capacitors were formed in the same manner as in Example 1 except that a resin film made of nylon resin was provided on the outer surface of the metal case, and the marking portion was formed by a conventional UV curable ink printing method. Manufactured.

  Specifically, using a UV curing device, a barcode display was printed by attaching and curing a UV curable ink to the bottom surface of a metal case coated with nylon resin. At this time, the thickness of the resin film was about 15 μm, and the thermal decomposition temperature of this nylon resin was 225 degrees.

(Comparative Example 2)
Twenty electrolytic capacitors were manufactured by the same method as in Example 1 except that the resin film was the same as that of Comparative Example 1.

(Friction test)
The electrolytic capacitors manufactured in Examples 1 and 2 and Comparative Examples 1 and 2 each had a rated voltage of 16 V and a rated capacity of 390 μF. Each electrolytic capacitor had a diameter of 8 mm and a height of 12 mm.

  About each manufactured electrolytic capacitor, with respect to the marking part which consists of barcode display, the wiping operation was performed 10 times with the paper which contained ethanol, and the friction test was done. And the appearance defect of the marking part after a friction test was observed. In addition, the thing with the marking part floating and peeling off by visual observation was defined as a poor appearance. The results are shown in Table 1.

(Reading test)
A bar code display reading test was performed on each marking portion after the friction test, and a product for which product information could not be obtained by reading the bar code display was regarded as a reading failure. The results are shown in Table 1.

  Referring to Table 1, after the friction test, the electrolytic capacitors of Examples 1 and 2 and Comparative Example 1 did not show poor appearance, whereas the electrolytic capacitor of Comparative Example 2 had 16 appearances. It was determined to be bad.

  In the friction test, the appearance defect occurred in Comparative Example 2 because the melting point of the nylon resin was low and the gasification temperature was low, the resin part in the vicinity of the irradiated area was removed, and the resin part was lifted off and peeled off. It was thought that it was because of.

  Further, referring to Table 1, in the barcode reading test, product information could be obtained for the electrolytic capacitors of Examples 1 and 2, whereas for the electrolytic capacitors of Comparative Examples 1 and 2, 11 out of 20 were obtained. Product information could not be obtained with 5 out of 20 electrolytic capacitors.

  In the barcode reading test, reading failure did not occur in the electrolytic capacitors of Examples 1 and 2 because the thermal deformation temperature of the epoxy resin used in Examples 1 and 2 and the melting point of the PET resin were high, and the respective gases This is probably because only the resin film in the portion irradiated with the laser was accurately removed and the metal case under it was exposed accurately.

  On the other hand, in the barcode reading test, the reading failure occurred in the electrolytic capacitor of Comparative Example 2 because the melting point of the nylon resin is low and the gasification temperature is low, the resin portion in the vicinity of the irradiated region is removed, This is probably because the metal case in a different area from the code display was exposed. Further, the reason why the reading failure occurred in the electrolytic capacitor of Comparative Example 1 is considered that it is difficult to accurately print the barcode display with the UV curable ink.

<Examination 2>
Example 3
By the same method as (1) to (3) in Example 1, an electrolytic capacitor was prepared in which a capacitor element was enclosed in a metal case provided with an epoxy resin film on the outer surface. And the marking part was formed by the process of the following (5).

(5) Step of forming the marking portion A laser beam is irradiated on the bottom surface of the metal case, and the mark (hereinafter referred to as “mark A”) shown in FIG. 5 is made up of figures, alphabets, and hatched figures. The marking part which displays.) Was formed. The mark A was set to a size such that when the mark A was surrounded by a circle indicated by a dotted line in the figure, the diameter of the circle was 7 mm.

  That is, using a YAG laser device (manufactured by SUNX, LP-F10R) on the bottom surface of the metal case, the laser is irradiated for 0.5 seconds at a laser power of 50% so that the laser irradiation area is the black portion of the mark A. Irradiated. Thereby, the marking part which displays the mark A was formed by removing the resin of the part (black part of the mark A) irradiated with the laser, and exposing the metal under it. Fifty electrolytic capacitors were manufactured through the above steps (1) to (3) and (5).

Example 4
Fifty electrolytic capacitors were manufactured in the same manner as in Example 3 except that the laser power applied to the bottom surface of the metal case was 100%.

(Example 5)
Fifty electrolytic capacitors were manufactured in the same manner as in Example 3 except that a resin film made of the same PET resin as in Example 2 was provided on the outer surface of the metal case. At this time, the thickness of the resin film was about 15 μm.

(Example 6)
50 electrolytic capacitors were manufactured in the same manner as in Example 5 except that the laser power applied to the bottom surface of the metal case was set to 100%.

(Comparative Example 3)
Fifty electrolytic capacitors were manufactured in the same manner as in Example 3, except that the same resin film made of nylon resin as in Comparative Example 1 was provided on the outer surface of the metal case. At this time, the thickness of the resin film was about 15 μm.

(Comparative Example 4)
Fifty electrolytic capacitors were manufactured in the same manner as in Comparative Example 3 except that the laser power applied to the bottom surface of the metal case was 100%.

(Friction test)
The electrolytic capacitors manufactured in Examples 3 to 6 and Comparative Examples 3 and 4 each had a rated voltage of 16V and a rated capacity of 220 μF. Each electrolytic capacitor had a diameter of 8 mm and a height of 12 mm.

  About each manufactured electrolytic capacitor, the marking part which displays the mark A was wiped 10 times with the paper which contained ethanol, and the friction test was done. And the appearance defect of the marking part after a friction test was observed. In addition, the thing with the marking part floating and peeling off by visual observation was defined as a poor appearance. The results are shown in Table 2.

  With reference to Table 2, the electrolytic capacitors of Examples 3 to 6 did not show poor appearance, but in Comparative Examples 3 and 4, 35 out of 50 and 40 were judged as poor appearance, respectively. . Then, when the marking part of Comparative Examples 3 and 4 determined to have a poor appearance was observed with a scanning electron microscope (SEM), the resin film near the black part of the mark A was peeled off and floated, It was also found that a part of the resin part located outside the irradiation region was partially removed. On the other hand, when the marking portions of Examples 3 to 6 were observed in the same manner, peeling or removal of the resin portion located other than the irradiated portion was not observed.

  This is because the thermal deformation temperature of the epoxy resin used in Examples 3 to 6 and the melting point of the PET resin are high, and the gasification temperature is high, so that only the portion irradiated with the laser is accurately removed. On the other hand, since the melting point of the nylon resin used in Comparative Examples 3 and 4 is low and the gasification temperature is low, the resin part in the vicinity of the irradiated region is removed, and it is considered that the nylon part is lifted off and peeled off. It was.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  INDUSTRIAL APPLICABILITY The present invention can be widely used for electrolytic capacitors, and can be suitably used for manufacturing electrolytic capacitors using a metal case.

  DESCRIPTION OF SYMBOLS 10 Capacitor element, 11 Metal case, 11a Side surface, 11b Bottom surface, 12 Sealing member, 13 Seat plate, 14A, 14B Lead wire, 15A, 15B Lead tab, 16 Resin film, 20 Winding body, 21 Anode body, 22 Cathode body , 23 Separator, 24 Winding tape.

Claims (4)

A step of accommodating a capacitor element in a metal case provided with an outer surface of a resin film made of epoxy resin or polyethylene terephthalate resin;
Irradiating the metal case with a laser to form a marking portion, and
The method of manufacturing an electrolytic capacitor, wherein in the step of forming the marking portion, the marking portion is formed by removing the resin film in a portion irradiated with the laser.   The marking portion includes a groove portion formed on the outer surface of the metal case by removing the resin film, and a side surface of the groove portion is partitioned by the resin film, and a bottom surface of the groove portion is the resin film. The method of manufacturing an electrolytic capacitor according to claim 1, wherein the electrolytic case is partitioned by an outer surface of the metal case exposed by removing the metal.   The method for manufacturing an electrolytic capacitor according to claim 2, wherein a groove width of the groove portion is 100 μm or less.   The said marking part is a manufacturing method of the electrolytic capacitor in any one of Claim 1 to 3 containing a barcode display.

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