JPH0618157B2 - Method of manufacturing electrolytic capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a method of manufacturing an electrolytic capacitor, which has no spacer and is small in size, high in performance, and capable of meeting market demands such as flame retardancy.

(Prior Art) Conventionally, for example, an aluminum electrolytic capacitor has an anode foil in which 999.99% or more of aluminum foil is electrochemically etched to expand the surface and an oxide film is formed by chemical conversion treatment, and 99%.
Similar to the above anode foil, aluminum foil is electrochemically etched to form a device by winding a spacer between cathode foils whose surface is enlarged, with a spacer interposed therebetween, and the device is impregnated with a driving electrolyte solution, and then in a case. It is housed and the opening of the case is sealed.

Generally, the purpose of interposing a spacer is to insulate and insulate a pair of positive and negative electrode foils and to retain a driving electrolytic solution, which is an important constituent factor in a dry foil electrolytic capacitor. The commonly used spacer is kraft paper, and the kraft paper has a density of 0.3 to 0.8 g / cm ^3.
The density is relatively high, and the fibers are flat and crushed, so the apparent specific resistance becomes large and the tan δ characteristic is impaired. Also, kraft paper has a thickness of 30μ due to problems in papermaking technology.
Since the thickness is more than m, it cannot be made thinner anymore, which is a factor for hindering miniaturization. Further, there is a drawback that ignition may occur at the time of capacitor breakdown due to application of overvoltage or reverse voltage, and continuous combustion may occur. For this reason, there is a tendency to use low-density manila paper instead of kraft paper, which greatly contributes to the improvement of tan δ characteristics, but the cost of manila paper is several times higher than kraft paper, and the strength after papermaking is also increased. In order to withstand the manufacturing process of capacitors (especially the winding process), the thickness should be 4
Since the size of 0 μm or more must be used, it becomes a bottleneck for downsizing, and at the same time, the use of paper as a spacer remains unchanged, and the risk of ignition due to capacitor destruction and continued combustion cannot be eliminated. Since a spacer is interposed between the coils and the coil is wound, the coiling device is complicated, and as a result, it becomes a factor that hinders the efficiency improvement of the capacitor element winding work, resulting in many practical defects.

Therefore, the Applicant aims to eliminate various defects by using the spacers as described above.
There is a technology applied for in No. 05. That is, the prior-art technique is to form a coating film by applying a photosensitive heat-resistant resin in a mesh form on one surface or both surfaces of one or both of an anode foil and a cathode foil made of aluminum that has been subjected to etching treatment. It is designed such that the network resin coating film that is closely formed by irradiating the surface with ultraviolet light and then subjecting it to heat treatment serves as a spacer, which greatly contributes to the demands for improved characteristics and compactness and flame retardancy. Is. However,
In the technology having the above-mentioned configuration, since the coating film of the photosensitive heat-resistant resin on the anode foil and the cathode foil is formed after the surface is roughened by etching, a high-viscosity photosensitive heat-resistant resin is used when forming the coating film. As a result, the resin film is coated on the etching pit due to the capillary phenomenon,
It was an alienation factor for reducing the capacitance per cm ^{2 of the} foil and achieving the desired miniaturization.

(Problems to be solved by the invention) Compared to the case where a spacer is interposed by closely forming a mesh-like resin coating film on the anode foil and the cathode foil that have been subjected to the etching treatment as described above, and serving as a spacer. It is possible to improve tan δ characteristics and flame retardancy, and to a certain extent, but it is possible to expect a more effective miniaturization due to the reduction of the capacitance per cm ^{2 of the} foil due to the coating resin entering the etching pits. It wasn't something.

The present invention has been made in view of the above points, and secures an effective capacitance per cm ² of the foil, and provides a method of manufacturing an electrolytic capacitor in which a separator that can contribute to a large size reduction is eliminated. It is intended.

[Structure of the Invention] (Means for Solving Problems) A method for producing an electrolytic condensor according to the present invention comprises a mesh-shaped or linear resin coating on one surface or both surfaces of each of a pair of valve action metal foils. A step of forming a film in close contact, and after the step, a portion of one metal raw foil on which the resin coating film is not formed is etched to increase the surface area to form a cathode foil, and the other metal raw foil does not form the resin coating film. A step of etching-forming chemical conversion treatment to form an oxide film on the etched surface to form an anode foil, and then attaching lead terminals to arbitrary portions of the anode foil and the cathode foil and contacting the resin coating surfaces. It is characterized in that it sequentially undergoes a process of forming a capacitor element by laminating and winding an anode foil and a cathode foil.

(Function) According to the method of manufacturing an electrolytic capacitor configured as described above, since the method is to perform etching after forming the resin coating film and chemical conversion treatment in the case of an anode, both the anode foil and the cathode foil are coated with the resin coating film. Is a mask, the etching pits do not grow (erosion) in this part during etching, and the etching pits grow in the part where the resin coating film is not formed. The factor of the capacitance reduction can be removed without entering.

(Example) Hereinafter, the detail of this invention is demonstrated with reference to drawings.

Example 1 As shown in FIG. 2, for example, a coating material composed of a polyimide-based photosensitive heat-resistant resin, a polyamide-based photosensitive heat-resistant resin, an epoxy-based photosensitive heat-resistant resin, etc. For example, a coating film 2 is formed by coating using any means such as roller coating, doctor blade, bar coater or spin coating, and after pre-baking, as shown in FIG. 3, the coating film 2 surface is shown in FIG. As described above, for example, a mesh-like mask 4 having a plurality of through-holes 3 is brought into close contact with it and irradiated with ultraviolet rays 5, and then the mask 4 is removed, a pattern is removed by developing with a developing solution, and further immersed in a rinsing solution, followed by room temperature air. Medium drying is performed to remove portions other than the exposed-developed portion of the coating film 2, that is, the portion of the mask 4 located in the through hole 3 to 100-
Heat treatment is performed at 300 ° C. for 10 to 30 minutes to closely form a network resin coating film 2 having a thickness of 2 to 10 μm as shown in FIG.
Next, the other surface and the portion where the network resin coating film 6 is not formed are subjected to electrochemical etching to roughen the surface, followed by chemical conversion treatment to form an anodic oxide film on the roughened surface. As shown in FIG. 6, for example, the same coating material as used for forming the anode foil 7 is used on one surface of the original aluminum foil 8 having a purity of 99%.
An anode foil 10 is prepared, in which a mesh resin coating film 9 having a thickness of 10 μm is formed in close contact, and then electrochemically etched to roughen the other surface and a portion where the mesh resin coating film 9 is not formed. To do. Next, as shown in FIG. 1, the lead-out terminals 11 and 12 are attached to the anode foil 7 and the cathode foil 10, and the laminated winding capacitor without the mesh resin coating film 6 and the mesh resin coating film 9 contacting each other. The element 13 is formed. Then, the element 13 is impregnated with the driving electrolytic solution, and then housed in an outer case (not shown), and the outer case opening is sealed with a sealing body.

Example 2 As shown in FIG. 7, for example, a thermosetting resin made of epoxy or the like is pattern-printed in a mesh pattern on one surface of a high-purity aluminum raw foil 14 having a purity of 99.99% or more, and a heat treatment is applied at 85 to 105 ° C. 2 A mesh resin coating film 15 having a thickness of 10 μm is formed in close contact, and then electrochemically etched to roughen the other surface and a portion where the mesh resin coating film 15 is not formed,
Then, as shown in FIG. 8, an anode foil 16 having a roughened surface and anodized film formed on the roughened surface and, for example, 99% pure aluminum original foil 17 are provided with the same means for forming the anode foil 16 on one surface thereof. Take a 2-10 μm thick net-like resin coating film 18
Then, an anode foil 19 is prepared, which is formed by closely adhering, and then is electrochemically etched to roughen the other surface and the portion where the network resin coating film 18 is not formed. Next, the same means as in the above embodiment is taken to obtain an electrolytic capacitor.

The electrolytic capacitor obtained by the above means is
Since the net-like resin coating films 6, 9 and 15, 18 forming the anode foils 7 and 16 and the cathode foils 10 and 19 are subjected to an etching treatment after formation, the net-like resin at the time of etching as shown in FIG. The portions where the coating films 6, 9 and 15, 18 are formed in close contact serve as a mask for etching, and this portion is not etched, and the other portions, that is, the network resin coating films 6, 9, 15 and 18 are formed. It has a structure in which pits 20 grow by etching only in the non-existing portion. Since there is no network resin coating film originally in the pit growing portion due to etching, there is no resin entering the pit growing portion due to etching, and the capacitance decreases. Will be resolved.

Next, a comparison of the product dimensions and electrical characteristics of the present invention (A), the reference example (B) and the conventional example (C) will be described.

The anode foil of the present invention-Aluminum original foil having a purity of 99.99% and one side of solid content% N-methyl-2pyrrolidone as a solvent are used. Polyimide-based photosensitive heat-resistant resin coating material is diethylene glycol dimethyl ether. Polymer concentration is 18% and viscosity is 1.
The coating film was adjusted to 00 cps to form a coating film by roller coating, the coating film was immediately polybaked at 80 ° C. for 10 minutes, and aluminum having a through hole with a hole diameter of 0.5 mm was provided at a porosity of 67% on the coating film surface. The mesh mask made of the above is adhered and exposed to a mercury lamp (300 to 400 mm) for 10 minutes to expose the coating film located in the through hole portion. Then N-
Ultrasonic dipping was performed for 2 minutes using a mixed solution of 85 parts of methyl-2pyrrolidone and 15 parts of methanol to develop the exposed area and pattern removal, and then dip in a methanol solution for 10 seconds to rinse and rinse the coated film except the developed area. And dry in air at room temperature, and then leave at 200 ° C for 30 minutes to obtain a thickness of 2
An anode foil in which a mesh-shaped resin coating film of μm is formed in close contact and then subjected to etching-chemical conversion treatment by a usual means.

Anode foil-a cathode foil in which a 2 μm-thick network resin coating film was adhered and formed on one surface of an original aluminum foil having a purity of 99% by the same means as the above-mentioned anode foil and then etched by usual means.

Lead terminals are attached to each of the anode foil and the cathode foil, wound, and impregnated with an ethylene glycol-adipic acid diameter paste as a driving electrolytic solution and housed in an aluminum case. Rating 2
5VDC-220μF electrolytic capacitor (A).

Reference Example Anode Foil-Aluminum foil having a purity of 99.99% was roughened to enlarge the surface, and then an anodic oxide film was formed. Then, a mesh resin coating film having a thickness of 2 μm was formed on one side by the same means as that of the present invention. Anode foil formed in close contact.

Cathode foil-A cathode foil in which a surface of a 99% pure aluminum foil is roughened, the surface is enlarged, and a 2 μm-thick network resin coating film is adhered and formed on one surface by the same means as the anode foil.

Lead terminals are attached to each of the anode foil and the cathode foil, wound, and impregnated with an ethylene glycol-adipic acid paste as a driving electrolytic solution and housed in an aluminum case. Rating 2
5VDC-220μF electrolytic capacitor (B).

Conventional example Anode foil-Anode foil with a 99.99% pure aluminum foil surface roughened to increase the surface area and then form an anodized film.

Cathode foil-A cathode foil with a 99% pure aluminum foil roughened surface area.

Spacer-Manila paper with a thickness of 40 μm.

Rating 2 in which a capacitor element formed by winding the anode foil and the cathode foil with the spacer interposed therebetween is impregnated with an ethylene glycol-adipic acid paste as a driving electrolyte.
5VDC-220μF electrolytic capacitor (C).

Then, as a result of comparison between the electrolytic capacitor of the present invention (A), the reference example (B), and the conventional example (C), product dimensions and electrical characteristics, the results are shown in the table.

As is clear from the above table, the present invention (A) has excellent capacitance, loss, and leakage current, and can be made smaller than the reference example (B) and the conventional example (C). We have shown the results that can greatly contribute to the market demand for short, small, light and thin products. However, the reason for miniaturization of the present invention (A) is that the capacitance per unit area of the anode foil, that is, the conventional example (C) 5.4 to 5.
5μF / cm ^2, Reference Example (B) 4.4~4.5μF / cm ^2, if the invention of (A) 5.2~5.3μF / cm ² and a difference in the conventional example (C), using spacers It had to be done.

In the above examples, the explanation was given by exemplifying the one in which the mesh resin coating film is provided on each of the anode foil and the cathode foil, but the mesh resin coating film is formed on both surfaces of the anode foil or both surfaces of the cathode foil, The same effect can be obtained even if the opposite electrodes are used as they are. Further, the mesh resin coating film shape is not limited to those exemplified in the above examples, and not only the mesh resin coating film having various shapes,
Needless to say, it may be a simple linear resin coating film. Further, in the above-mentioned embodiment, the case where the aluminum foil is used as the anode foil and the cathode foil has been described as an example, but the one using the valve action metal foil such as tantalum, titanium, and niobium can be applied.

[Effects of the Invention] As described above, according to the present invention, it is possible to obtain a method of manufacturing an electrolytic capacitor having high practical value, which is capable of maintaining excellent various characteristics and greatly contributing to miniaturization.

[Brief description of drawings]

1 to 6 are explanatory views for explaining a method of manufacturing an electrolytic capacitor according to an embodiment of the present invention. FIG. 1 is a development view showing a capacitor element, and FIG. 2 is one surface of an aluminum original foil. A partially cutaway enlarged perspective view showing a state in which a coating film is formed,
FIG. 3 is a partially cutaway enlarged perspective view showing a state in which a mesh mask is brought into close contact with the coating film surface and irradiated with ultraviolet rays, FIG. 4 is a partially cutaway enlarged perspective view showing the mesh mask, and FIG. FIG. 6 is a partially cutaway enlarged perspective view showing an anode foil having a mesh resin coating film formed thereon. FIG. 6 is a partially cutaway enlarged perspective view showing a cathode foil having a mesh resin coating film formed on one surface thereof. FIG. 7 relates to a method of manufacturing an electrolytic capacitor according to another embodiment of the present invention. FIG. 7 is a partially cutaway enlarged perspective view showing an anode foil having a mesh resin coating film formed on one surface, and FIG. A partially cutaway enlarged perspective view showing a cathode foil having a mesh resin coating film formed on one surface,
FIG. 9 is an enlarged sectional view showing a pit state due to etching of the anode foil or the cathode foil obtained by the present invention. 1,8,14,17 …… Aluminum original foil 6,9,15,18 …… Resin resin coating 7,16 …… Anode foil 10,19 …… Cathode foil 11,12 …… Lead terminal 13 …… Capacitor element

Claims (1)

[Claims] 1. A step of closely forming a mesh-like or linear resin coating film on one surface or both surfaces of each of a pair of valve action metal raw foils, and the resin of one metal raw foil after the step. A step of etching a part where a coating film is not formed to expand the surface area to form a cathode foil, and a part of the other metal raw foil where the resin coating film is not formed to be subjected to etching-chemical conversion treatment to form an oxide film on the etched surface to form an anode foil. Then, a step of sequentially forming a capacitor element by attaching lead-out terminals to arbitrary portions of the anode foil and the cathode foil and winding the anode foil and the cathode foil in a laminated manner without the resin coating surface surfaces contacting each other. A method of manufacturing an electrolytic capacitor, characterized in that