JPS6378515A - Manufacture of electrolytic capacitor - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Purpose of the Invention] (Field of Industrial Application) The present invention is a 1Q electrolytic capacitor that eliminates spacers and meets market demands for small, high performance, flame retardant, etc. ! I decide how to make it.

(Prior Art) Conventionally, a dry foil type electrolytic capacitor connects a pair of anode and cathode foils made of aluminum foil to a pair of lead terminals also made of aluminum, with a spacer interposed between the pair of anode and cathode foils. It is wound, impregnated with a driving electrolyte, stored in a case, and the opening of the case is sealed. Generally, the purpose of interposing a spacer is to insulate and isolate a pair of anode and cathode foils and to retain a driving electrolyte, which is an important component in a dry foil electrolytic capacitor. However, the commonly used spacer is kraft paper, but the kraft paper has a density of 0.3 to
It has a relatively high density of 0.8 g/era 3, and the fibers are flattened, which increases the apparent resistivity and impairs the tan δ properties. The thickness is 30 μm or more, and it cannot be made any thinner, which hinders miniaturization.Furthermore, there is a risk of ignition and continued combustion when the capacitor is destroyed due to overvoltage or reverse voltage application. Therefore, there is currently a trend to use low-density manila paper instead of kraft paper, which greatly contributes to improving tanδ characteristics.
Manila paper is several times more expensive than kraft paper, and in order to have the strength after paper assembly to withstand the capacitor manufacturing process (especially the winding process), it must be 40 μm or thicker. At the same time, paper is still used as a spacer, and the risk of ignition and continued combustion when the capacitor breaks remains unresolved.
Furthermore, since winding is performed with a spacer interposed between a pair of anode and cathode foils, the winding device becomes more complicated, which results in many practical drawbacks such as hindering the efficiency improvement of capacitor element winding work. ing.

(Problems to be Solved by the Invention) As described above, the use of spacers not only obstructs miniaturization but also poses a risk of combustion, and also complicates the winding device and improves the efficiency of element winding work. This was a hindering factor.

The present invention has been made in view of the above points, and can meet market demands for miniaturization and flame retardancy by achieving good characteristics without using spacers, and can greatly contribute to cost reduction by simplifying the manufacturing process. The purpose of the present invention is to provide a method for manufacturing an electrolytic capacitor with high practical value.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a teng material consisting of a photosensitive heat-resistant resin on both sides of either an anode foil or a cathode foil made of a valve metal, or one side of both. After coating and baking, a mesh mask with a plurality of through holes of any shape and size is placed on the surface of the coated film and exposed to light.Then, the mask is removed and the pattern is cut out. After removing the parts of the membrane other than those located at the through-holes, heat treatment is performed to form a mesh-like resin coating on the electrodes, and lead terminals are attached to the anode foil and cathode foil, and the attachment parts and This method is characterized in that the end faces of the anode foil and the cathode foil are surrounded by a resin film, and then the pair of anode foil and cathode foil are stacked 56 times to form a capacitor element.

(Function) According to the above-mentioned means, compared to a spacer formed tightly on the electrode instead of a spacer, a thin mesh-like resin coating is used, which is superior in miniaturization and flame retardancy. Since the end faces of the anode foil and the cathode foil are surrounded by a resin film, there is no risk of short-circuiting, and furthermore, the device winding work can be greatly improved.

(Example) An embodiment of the present invention will be described in detail below.

That is, first, for example, the surface of an aluminum foil is roughened with an etching solution to increase the surface area, and then an anodized film is applied to produce an anodized film. Prepare an enlarged cathode foil. Next, as shown in Figure 2,
Polyimide-based photosensitive heat-resistant resin on both sides of the cathode foil (1),
Coating material T31 made of polyamide photosensitive heat resistant resin, epoxy photosensitive heat resistant resin, etc. is used, for example, by roller coating or doctor blade.

A coating 11!3 (2) is formed by coating using any means such as a bar coater or a spin code, and after baking, as shown in FIG. For example, a mesh mask (4) provided with a plurality of through holes (3) is placed in close contact with the mask and exposed to ultraviolet light (5).
After that, the mask (4) was removed, developed with a developer, treated as a pattern, and further immersed in a rinsing solution ((
Dry in air at room temperature, remove the exposed and developed part of the coating film (2), that is, the part other than the part located in the first hole (3) of the mask (4), and heat treat at 100 to 300°C for 10 to 30 minutes. As shown in Figures 5 and 6, the cathode foil (
1) A mesh resin coating film (6) with a thickness of 2 to 20 μm is closely formed on both sides. Next, as shown in Figures 7 to 9, the fifth
As shown in the figure and FIG. 6, a thermosetting polyimide resin liquid is applied to all end faces of the cathode foil (1), and a resin film (7) having a thickness of 10 μm is formed under heating conditions of 180° C. for 30 minutes. On the other hand, as shown in FIGS. 10 to 12, the entire end surface of the anode foil (8) prepared in advance was
A resin film (9) of μm is formed. However, next, the first
Anode foil (8) on which the resin film (9) is formed as shown in the figure
The cathode foil (1) on which the resin film (7) is formed is wound using a V1 winder (not shown) to form a capacitor element (1).
0). In addition, in the middle of winding, the anode lead terminal (11) is stitched or ultrasonic welded to the front &! Attach the cathode lead terminal (12) to the anode foil (8) and the cathode foil (1), respectively, apply a thermosetting polyimide resin liquid to the attachment portion, and form under heating conditions at 180° C. for 30 minutes. It is surrounded by a resin film C13) having a thickness of 10 μm. Then, the Content+1 element (10) is impregnated with a driving electrolyte, then stored in an outer case (not shown), and the opening of the outer case is sealed with a sealing body to form a finished product. .

In the electrolytic capacitor obtained by the manufacturing method configured as described above, the mesh resin coating (6) provided on the cathode foil (1) is different from the anode foil (8) constituting the capacitor element (10).
) and the cathode foil (1), and the driving electrolyte is sufficiently retained between them, and the insulation separation between the anode foil (8) and the cathode foil (1) can be maintained at 1 minute, and no spacer is required. It is effective in improving the characteristics characterized by tan δ without using it.

In addition, the mesh resin coating (6) has superior heat resistance compared to the spacer, so even if the capacitor is destroyed due to overvoltage or reverse voltage application, the only temporary spark or flash of decomposed gas (less than 1 second) will prevent the spacer from being removed. It never ignites and burns like the ones used. Furthermore, when using a spacer υ, there are various restrictions as mentioned above.
µm, whereas Manila paper has a thickness of 40 µm, in the case of the mesh resin coating (6), a thickness of 2 to 20 µm is sufficient to retain the driving electrolyte and insulate the anode foil (8) and cathode foil (1). In addition to being significantly smaller in size to enable isolation, the cathode foil (1) simply forms a mesh resin coating (6) without using any spacers. Since the two sheets of i-electrode foil (8) are simply laminated facing each other and wound, the winding work is simplified and the workability is improved, which contributes to cost reduction. with a resin film (7) and an anode foil (8).
), the resin film (9) surrounds the attachment parts of the anode lead terminal (11) and cathode lead terminal (12) with the resin film (13), so that the cathode foil (1) and the anode foil ( 8) It has many advantages, including the fact that there is no risk of direct contact with the counter electrode foil through the attachment parts of the anode lead terminal (11) and cathode lead terminal (12), which is extremely effective in preventing short circuits.

In addition, in the above example, the mesh resin coating (6) was coated with a cathode foil (
Although the anode foil (8) formed on both sides of the anode foil (8) used as the counter electrode in 1) is used as it is, the cathode foil (8) formed on both sides of the anode foil is used as the counter electrode. The same effect can be obtained by using the same structure as it is, or by forming a network resin coating on one side of each of the anode foil and the cathode foil. Furthermore, the shape of the mesh-like resin coating film is not limited to those exemplified in the above embodiments. The same effect can be obtained even if the shape is changed in various ways.

Furthermore, in the above embodiment, the anode foil (8) and the cathode foil (1)
The explanation has been given using aluminum foil as an example, but for example, tantalum or titanium may be used.

Valve metals such as niobium f! This can be applied to items using foil.

Next, an example of comparison between an embodiment of the present invention and a conventional reference example will be described.

Example Anode Foil After roughening the aluminum foil surface and expanding the surface area, an anodic oxide film was formed, and the end surface was surrounded by a polyimide resin film. foil.

Cathode foil Aluminum foil The surface of the cathode foil has been roughened to increase its surface area.On both sides of the cathode foil, the solid content is 18%.Polyimide-based photosensitive heat-resistant resin containing N-methyl-2-pyrrolidone as a solvent is coated with diethylene glycol dimethyl ether, and the polymer concentration is 18%. , the viscosity was adjusted to 100 cps, a coating film was formed by roller coating, and the coating film was immediately heated to 80°C-1
After bribing and kinging for 0 minutes, an aluminum mesh mask with a 67% aperture ratio of through holes with a diameter of 0.5ffill was placed on the coated film surface, and a mercury lamp (3
00 to 400 M) for 10 minutes to expose the coating film located in the through hole. Next, ultrasonic immersion was performed for 2 minutes using a mixed solution of 85 parts of N-methyl-2-pyrrolidone and 15 parts of methanol, the exposed area was developed and the pattern was cut out, and then the coated film was immersed in a methanol solution for 10 seconds to rinse. The cathode foil was dried in air at room temperature, and left at 200°C for 30 minutes to form a 2 μm thick mesh resin coating, and all edges of the cathode foil were surrounded by a polyimide resin film. .

The anode foil and the defeating foil are laminated, a lead terminal is taken out from each of the anode foil and the cathode foil, and a thermosetting polyimide resin liquid is applied to the attachment portion and hardened to seal the attachment portion with resin. An electrolytic capacitor with a rating of 25V-220μF (^), surrounded by a membrane, formed into a wound capacitor element by the method shown in Figure 1, and impregnated with ethylene glycol-adipic acid paste as a driving electrolyte.

Reference Example Anode Foil Anode foil in which an anodized film is formed by roughening the aluminum foil surface and expanding the surface area.

Cathode foil aluminum Cathode foil with a roughened surface to expand the surface area.

Spacer J17 40μm Manila paper.

Rating 2, in which a capacitor element formed by winding between the anode foil and the cathode foil through the space is impregnated with an ethylene glycol-adipic acid paste as a driving electrolyte.
5V-220μF electrolytic capacitor (B).

Therefore, the electrolytic capacitor of Example (A) according to the present invention can be reduced in volume by about 20% compared to the conventional electrolytic capacitor of Reference Example (8), which contributes to miniaturization. Also an example (^).

Reference example (B) As a result of preparing 20 samples for each sample and investigating the combustion situation when a voltage twice the rated voltage was applied to destroy them, it was found that in reference example (8), all 20 samples emitted sparks or flashes, and 8 of them emitted sparks or flashes. In contrast, in Example (8), only a spark or a flash of light was emitted, and none of the samples ignited and continued to burn, demonstrating excellent flame retardant properties. Furthermore, the winding operation was simple, as it was simply winding the anode foil and the cathode foil, and the winding efficiency was greatly improved. Next, the capacitance change rate with respect to temperature, tan δ, and frequency-impedance characteristics of Example (A) and Reference Example (B) were investigated, and the results were as shown in FIGS. 13 to 15.

As is clear from FIGS. 13 to 15, it can be seen that Example (A) is more stable than Reference Example (B) in all characteristics.

In addition, apart from the above characteristic comparison, Example (A) of the present invention was the same as the present invention except that the end faces of the cathode foil and anode foil and the attachment portions of the cathode and anode lead-out terminals were not surrounded with a resin film. As a result of investigating the occurrence of short-circuit failures with Reference Example (C) configured as shown in FIG.

Margin below [Effects of the Invention] According to the present invention, the characteristics are improved without using any spacers, the device is made smaller, flame retardant, there is no risk of short circuit, and the efficiency of element winding is greatly improved. A method for manufacturing electrolytic capacitors with high practical value that can contribute to cost reduction.

[Brief explanation of the drawing]

Figures 1 to 12 are explanatory diagrams for explaining a manufacturing method according to an embodiment of the present invention, in which Figure 1 is a developed view showing a capacitor element, and Figure 2 is a state in which a coating film is formed on both sides. FIG. 3 is an enlarged partially cutaway perspective view showing the cathode foil in which a mesh mask is brought into close contact with the coating film formed on both sides of the cathode foil and ultraviolet rays are irradiated. FIG. Partially cutaway enlarged perspective views showing the mesh mask, FIGS. 5, 13 and 6
The figures show a cathode foil with a mesh-like resin coating formed on both sides. Figure 5 is an enlarged partially cutaway perspective view, Figure 6 is a partially cutaway enlarged front view, and Figures 7 to 9 are full end faces. Figure 7 shows the cathode foil cut out in the middle after the resin film has been formed.
Figure 8 is a cross-sectional view taken along the line X-X in Figure 7, Figure 9 is a sectional view taken along Y-Y in Figure 7, and Figures 10 to 12 show the anode foil with a portion cut out after the resin film has been formed on the entire end surface. Figure 10 is a plan view, 1
Figure 1 is a cross-sectional view of Figure 10 x'-x', Figure 12 is Figure 10 Y
13 is a temperature-capacity change rate characteristic curve diagram, FIG. 14 is a temperature-tnδ characteristic curve diagram, and FIG. 15 is a frequency-inveneance characteristic curve diagram. (1)・・・Cathode foil (2)・・・・・・
Coating film (3)...Through hole (4)...
...mesh mask (5) ...ultraviolet rays
(6)...Mesh resin coating (7)...Resin film (8)...Anode foil (9)...
... Resin film (10) ... Capacitor element (11) ... Anode lead terminal (12) ...
... Cathode lead terminal (13) ...Resin film patent application Marukon Electronics Co., Ltd. Figure 6 S Figure 7 X-x decoy Figure 8 Figure 9 4 A% Pukoshir, attack-giaYig 1 Shino Sumi n Fig. 10 Fig. 11 Y'-Y' decoy drawing Fig. 12

Claims (1)

[Claims] A means for forming a coating film by coating and prebaking a coating material made of a photosensitive heat-resistant resin on both sides of either one of an anode foil and a cathode foil made of a valve metal, or one side of both, and a coating film formed by the means means for exposing a mesh mask having a plurality of through holes on its surface by irradiating ultraviolet rays from the surface of the mask, and removing the mask after the means, developing with a developer, and then subjecting the mask to a rinse heat treatment to form a mesh pattern. means for forming a resin coating; means for stacking the anode foil and the cathode foil facing each other and attaching the anode lead terminal to the anode foil and the cathode lead terminal to the cathode foil; and the attachment portion and the anode foil. manufacturing an electrolytic capacitor, comprising: a means for surrounding all end faces of a cathode foil with a resin film to form a wound capacitor element; and a means for impregnating the capacitor element with a driving electrolyte. Method.