JPS6276711A - Manufacturing electrolytic condenser - Google Patents

Abstract

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

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention generally involves forming a photosensitive film made of a photosensitive aromatic polymer on the surface of a specific anode foil or cathode foil, and then applying the film through a negative or bond film. A portion of the photosensitive film is photocured and developed using active light to form a large number of fine protrusions or a microporous film on the first surface, and the anode foil or cathode foil is used to form an electrolytic capacitor. The present invention relates to a method of manufacturing a small, high-performance electrolytic capacitor with good reproducibility without using a spacer made of G.

[Technical background of the invention and its problems]

Conventionally, a dry foil type electrolytic capacitor is constructed by connecting a pair of anode and cathode foils made of aluminum foil to a pair of lead terminals made of aluminum or the like, and interposing a spacer between the anode and cathode foils of the terminal 1. Let it roll, and after that,
It was manufactured by impregnating a drive electrolyte, storing it in a case, and sealing the opening of the case. Generally, as mentioned above, the purpose of intervening a spacer is to insulate and isolate a pair of anode foil and cathode foil and to retain a driving electrolyte, which is an important structural requirement in a dry foil electrolytic capacitor. The spacer used in the above-mentioned known manufacturing method is generally made of kraft paper, and the kraft paper has a density of 0.3 to 0.8.
g/cffl, which is relatively high, and because the fibers are flattened, the apparent resistivity is large (tan δ)
Regarding FM characteristics, kraft paper has a thickness of 30 μm or more due to limitations in paper-making technology, and cannot be made any thinner than this, which is a factor that hinders miniaturization. Therefore, currently
It has been proposed and partially implemented to manufacture electrolytic capacitors using low-density manila paper instead of kraft paper in the above-mentioned manufacturing method in an attempt to improve the drawbacks of the above-mentioned known manufacturing method or known electrolytic capacitors. However, in the improved electrolytic capacitor, the jan δ characteristics etc. are greatly improved, but Manila paper is several times more expensive than kraft paper, and in addition, the strength after paper making is reduced during the manufacturing process of electrolytic capacitors ( In order to withstand the winding process (in particular, the winding process), it is necessary to use a material with a thickness of 40 μm or more, which makes it difficult to downsize the spacer. Instead, a spacer is interposed between a pair of anode and cathode foils for winding, which complicates the winding device and becomes an impediment to improving the efficiency of winding the capacitor element. It has the following drawbacks.

[Purpose of the invention]

This invention has been made in view of the above points, and it can be manufactured without using paper spacers, has good electrical characteristics, and can meet market demands such as miniaturization and weight reduction. The purpose of this invention is to provide a method for manufacturing electrolytic capacitors that has high practical value and can greatly contribute to cost reduction by simplifying the process.

[Components of the invention]

In this invention, an F6 liquid of a photosensitive aromatic polymer is applied to both sides of either an anode foil or a cathode foil made of a valve metal, or one side of both, and dried to form a photosensitive film, and then On the photosensitive film formed on the surface of the foil, a "negative or positive film" having a large number of fine patterns is closely superimposed, and the photosensitive film is partially photocured by irradiating light, and then After removing the negative or positive film,
The unphotocured portion of the photosensitive film is removed with a developer and developed to expose the surface of the foil, forming a large number of fine projections or a large number of penetrations made of the photocured layer on the surface of the foil. A microporous film consisting of a photocured layer having holes is formed, and finally, the anode foil and the cathode foil are stacked on top of each other so that the protrusions or the microporous film are present between the anode foil and the cathode foil, and the lamination is performed. An electrolytic capacitor characterized in that the body is wound around to form a capacitor element, and this capacitor element is impregnated with a driving electrolyte! ! I! This is related to the I manufacturing method.

[Detailed explanation of each requirement of the invention]

Hereinafter, the method for manufacturing an electrolytic capacitor of the present invention will be explained in more detail with reference to the drawings.

In this invention, first, for example, aluminum, tantalum,
The anode foil made of a valve metal such as titanium or niobium and the cathode 7f3 (the cathode foil does not have to be made of a valve metal) are coated on either side or one side of both with active light such as visible light or ultraviolet light. Appropriate coating of an organic solvent solution of a photosensitive aromatic polymer such as photosensitive aromatic polyamide or photosensitive aromatic polyimide, which has a large number of "photosensitive groups" including ethylenically unsaturated groups that can be crosslinked (polymerized). The method is applied uniformly at a coating temperature of preferably about 5 to 50 °C, particularly 10 to 40 °C, and the solvent is preferably gradually removed from the coated film to dry the coated film (pre-haking).
However, jI is preferably about 0°1 to 40 μm, especially 0.
A solidified film (photosensitive film) of a photosensitive aromatic polymer having a thickness of 5 to 30 μm is formed.

The above-mentioned foil may be, for example, an aluminum foil, if necessary, whose surface is roughened with hydrochloric acid or an Enotinda solution containing a halide to increase its surface area, and then subjected to an anodizing treatment to form an anodized film. It is preferable to use an anode foil produced by the above-mentioned method, or a cathode foil whose surface area is expanded by roughening the surface of aluminum foil or the like with esotynda liquid in the same way as the anode foil.

For example, the photosensitive aromatic polymer can be photocrosslinked (photopolymerized) by active light such as visible light or ultraviolet light.
The polymer has a large number of "photosensitive groups" with ethylenically unsaturated groups that can be
Moreover, for example, N,N-dimethylformamide, N,
N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N-methyl-2
- High solubility in organic polar solvents such as pyrrolidone, dimethyl sulfoxide, hexamethylene phosphoramide, diglyme, etc., and ca.
Particularly preferred are photosensitive aromatic polymers such as photosensitive aromatic polyamides and photosensitive aromatic polyimides, which have heat resistance that can be used at high temperatures of 00 to 300° C. and resistance to sparks and the like.

Application of the photosensitive aromatic polymer solution can be carried out, for example, by
A coating film may be formed by coating to a uniform thickness using any means such as roller coating, a doctor blade, a bar coater, or a spin cord.

In drying the coating film, the drying temperature is about 20 to 2
It is preferable that the temperature is 00°C1, particularly about 30 to 150°C, and the drying time is about 0.1 to 100 minutes, particularly about 0.5 to 30 minutes.

In this invention, after forming a photosensitive film on the surface of the foil as described above, the portions that will become "many fine protrusions" etc. are then formed on the surface of the foil by photocuring the photosensitive film. A negative or positive film on which ``a large number of fine patterns'' are formed, which have a pattern corresponding to the planar shape of
are closely superimposed on the photosensitive film, and the photosensitive film is sufficiently irradiated with active light such as visible light or ultraviolet light that has passed through the negative or positive film to remove a part of the photosensitive film. In other words, the "portion that will become a large number of minute protrusions, etc." is sufficiently photocured so that it will not be easily dissolved in the current solution used in the next step, and then the negative or positive film is removed. After that, the uncured portions of the photosensitive film (i.e., the portions other than the photocured portions that form a large number of minute protrusions) are removed using a developer, and the surface of the foil in the uncured portions is exposed. ”, preferably about 0 to 80°C
Preferably, the entire surface of the foil is coated with a microporous film having "a large number of fine protrusions" or "a large number of minute through-holes" formed by photocuring of the photosensitive film at a temperature of It is formed uniformly over the entire area.

As mentioned above, the above-mentioned "negative or positive film" is a transparent part (a part that can transmit light rays) corresponding to parts such as "a large number of minute protrusions" formed on the surface of the anode and cathode foils.
If it is a film that has transparent and opaque parts with "many minute patterns" consisting of opaque parts and other opaque parts (parts that do not transmit light), what kind of species! It may have a pattern of n, for example, a dot, a circle, an oval, an arc, a crescent, a star, an L-shape, a cross, a quadrilateral (square, diamond, rectangle, etc.), a triangle ( Isosceles triangle, equilateral triangle, etc.), fine planar shapes such as hexagons (maximum length is preferably about 1 to 2000 μm, especially lO to 1000 μm)
A precise pattern in which a large number of "transparent parts" having a diameter of about 100% are arranged regularly and uniformly at appropriate intervals (preferably within a range of about 0.01 to 101%) In addition, the area of the transparent portion is approximately 20 to 70%, particularly 25 to 70%, of the total area of the negative or positive film.
The ratio is preferably about 60%.

Further, the material of the negative or bond film is not particularly limited, and may be made of the same material as that generally used for negative films such as photographs. Alternatively, one side of the positive film may be coated with an adhesive so that it can be brought into close contact with the photosensitive film of the foil.

In this invention, by photocuring a photosensitive film using the above-mentioned negative or positive film, a large number of extremely fine protrusions etc. are precisely and accurately arranged on the surface of the anode and cathode foil. Therefore, it can be easily formed with good reproducibility.

In the above-mentioned development, the developer may be one whose main component is the same organic polar solvent as the organic polar solvent used in the adjustment of f6/& of the photosensitive aromatic polymer, and the developer may be a developer. The operation involves not only simply immersing or contacting the foil with the irradiated photosensitive film in a developer, but also
It is preferable to apply ultrasonic waves at the same time.

The large number of minute protrusions J or "microporous membrane having a large number of through holes" made of the photocured layer formed on the surface of the foil insulates the anode foil and the cathode foil, and at the same time and the height and thickness of the protrusions or microporous membrane so that the electrolyte can be retained in the void or through-hole between the cathode foil and each protrusion), size, shape, and spacing of each protrusion or each through-hole. (For example, when forming a large number of minute protrusions, the height of each protrusion should be approximately 0.1 to 40 μm.)
m, especially 0.5 to 30 μm, more preferably 1 to 20 μm
The maximum length of each protrusion (maximum length in the same plane direction as the surface of the anode and cathode foil) is preferably about 1 to 2000 μm, particularly about 10 to 1000 μm. , and the cross-sectional area of each protrusion is approximately 0. l×10 ~10sZ, especially 1×10
~5m#, more preferably about 1x10~I-.

On the surface of the anode foil or cathode foil on which the above-mentioned "many fine projections" or "microporous membrane having many through holes" are formed, the fine projections or the microporous membrane (
The total area of the exposed surface of the foil that is not covered with the photocured layer is the same as the total area of the foil (the area on the side where many fine protrusions are formed). , about 30~
A proportion of the order of 80%, especially 40-75% is preferred, especially for capacitor performance.

As mentioned above, a large number of fine protrusions made of a photocured layer
The anode and cathode foils in which the above-mentioned anode and cathode foils are uniformly formed over the entire surface of the foil are further heated at a temperature of about 100 to 400°C, particularly at a temperature of about 120 to 400°C.
Heat treatment (post-bake) at a temperature of 250°C for about 5 to 60 minutes increases the adhesion between the many fine protrusions (photocured layer) and the surface of the foil. It is suitable for improving physical properties, chemical resistance, etc.

In this invention, finally, the above-mentioned large number of fine protrusions (protrusions made of a photocured layer) are formed on both surfaces of either one of the anode foil and the cathode foil or on one side of both of the anode foil and cathode foil produced as described above. Preferably, the above-mentioned large number of anode and cathode foils are coated with a microporous film consisting of a photocured layer having uniformly formed over the entire surface or a large number of microscopic through holes formed over the entire surface. The anode and cathode foils are appropriately combined and overlaid to form a top layer such that minute protrusions or microporous membranes exist between the anode foil and the cathode foil, and the laminate is wound to form a capacitor element, and This capacitor element is impregnated with a driving electrolyte to produce a high-performance electrolytic capacitor.

Examples of the driving electrolyte include an ethylene glycol-organic carboxylic acid electrolyte solution.

As an embodiment of the present invention, for example, as shown in FIG. 2, a solution of a photosensitive aromatic polymer is applied to both sides of a cathode foil 1 using an appropriate coating means to form a coating film, and the coating film is After drying (pre-haking) to form a photosensitive film (solidified film) 2 with a thickness of about 2 to 20 μm, as shown in FIG. 0
The transparent part 3, such as a small circle with a weight of about 1 to 2.0 weight, is wrapped around 0.
A large number of negative films 4 arranged at intervals of about 1 to 5 times are brought into close contact with each other, and an arrow P is shown from above the negative film.
The photosensitive film 2 is photocured by irradiating light from a mercury lamp in the direction of , and then the negative film 4 is removed.
A developing operation is performed using a developer to remove the uncured portion of the surface of the cathode foil and expose the first surface. , dry the entire cathode foil, and then dry at 100 to 200°C for 10 to 20 minutes.
Heat treatment is performed for 30 minutes, and as shown in FIGS.
A circular cross section of 30 μm and a diameter of about 0.01 to 2 va) was formed into a vIf shaped bottom. Next, as shown in FIG. 1, a cathode foil 1j having a large number of fine protrusions with a height of 0.5 to 30 μm closely formed on both sides and an anode foil prepared in advance, as shown in FIGS. 7 are laminated and then wound using a winder (not shown) to form a capacitor element 8.

Note that the anode lead terminal 9 is attached to the anode foil 7 and the cathode lead terminal 10 is attached to the cathode foil 1 in advance.

Then, the capacitor element 8 is impregnated with a driving electrolyte, then stored in an exterior case (not shown), and the opening of the exterior case is sealed with a sealing body to form a finished product (electrolytic capacitor). It is.

The electrolytic capacitor manufactured as described above has a cathode foil l
Since a large number of minute protrusions j provided in the capacitor element 8 are present between the anode foil 7 and the cathode foil 1,
The anode foil 7 and the cathode foil I are sufficiently insulated from each other, and also serve to form a suitable gap for holding the electrolyte, and furthermore, there is no need to use any paper spacers. This is effective in improving various capacitor characteristics including an δ. Furthermore, when using paper spacers, there are various restrictions as mentioned above. For example, the minimum thickness of paper spacers currently in practical use is 30 μm for kraft paper and 40 μm for Manila paper. On the other hand, in the case of the above-mentioned fine protrusion 6, the height is about 0.5~
It is easily possible to make the thickness of the electrode foil 1 to 30 μm, especially about 1 to 20 μm, and it is possible to sufficiently hold the driving electrolyte and insulate and isolate the cathode foil 7 and the cathode foil 1 with such a large number of fine protrusions. Therefore, the final electrolytic capacitor manufactured can be significantly miniaturized, and without using any paper spacer material, for example, the cathode foil l with a large number of minute protrusions 6 and the anode This method has many advantages, such as simply using two types of materials, stacking them facing each other and winding them, which simplifies the winding work and greatly contributes to cost reduction due to improved workability.

In the above embodiment, a large number of fine protrusions 6 are connected to the cathode 7f.
The anode foil 7 formed on both sides of the anode foil 7 to serve as the counter electrode has been described as an example of using the same as it is. may be used in combination with gold B foil as it is, or may be used in combination with anode foil and cathode foil each having a large number of fine protrusions formed on one side thereof.

In addition, as shown in FIG. 6, a negative or positive film with an optically completely opposite pattern is used, and instead of the above-mentioned large number of protrusions, a microporous film such as a mesh having a large number of through holes of 5° (
Exactly the same effect can be obtained with the cathode 7f31 (or anode foil) whose both sides (or one side) are covered at an angle of 6° (photocured layer).

〔Example〕

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

Example 1 As a cathode foil, an anode foil was prepared by roughening the surface of an aluminum foil with a thickness of 90 μm to expand the surface area and then forming an anodized film thereon. A cathode foil with an expanded surface area was prepared.

Photosensitive aromatic polyimide is coated on both sides of the cathode foil.
A photosensitive aromatic polymer solution (rotational viscosity: 100 centipoise) dissolved in N-methyl-2-pyrrolidone at a ratio of 0% by weight was applied using a roller coating device to form a coating film, and the coating film was immediately coated at 80% by weight. C. for 10 minutes (brining treatment) to form a 2 .mu.m thick photosensitive film on the cathode foil. On the surface of the photosensitive film of the cathode 2δ, a negative film having large and small circular transparent parts with a diameter of 0.5 am and a diameter of 0311 at an interval of about 0.75 layers was tightly attached, and the light from the mercury lamp ( Wavelength: 300-4501
In step m), the photosensitive film was irradiated with light for about 3 minutes to photocure the portions corresponding to the minute protrusions.

Next, using a mixture of 85 parts of N-methyl-2-pyrrolidone and 15 parts of methanol as a developer, and using ultrasonic waves together, the cathode foil with the irradiated photosensitive film was heated for 2 minutes. Development is performed, and the developer is rinsed by immersion in a methanol solution for 10 seconds to remove the uncured portion of the photosensitive film to form a large number of fine protrusions.Finally, the film is dried in air at room temperature. This was followed by heat treatment at 180° C. for 30 minutes to produce a cathode foil in which a large number of fine protrusions of 2 μm in height made of a photocured layer were formed in close contact with both surfaces of the cathode foil.

The anode foil and the cathode foil are laminated by the method shown in FIG. 1 so that a large number of fine protrusions exist between them, and the laminated body is wound to form a capacitor element, and further,
The capacitor element is impregnated with ethylene glycol-adipic acid paste as a driving electrolyte, and the rating is 25.
An electrolytic capacitor (A) of V, DC-220 μF was manufactured.

Comparative Example 1 An anode foil in which the surface of the aluminum foil was roughened to increase the surface area and an anodic oxide film was formed was prepared as the anode foil, and a cathode foil in which the surface of the aluminum foil was roughened and the surface area was expanded was prepared as the cathode foil. 40μ thick as spacer
I prepared a number of manila papers.

The spacer is sandwiched between the anode foil and the cathode foil to form a laminate, and a capacitor element formed by winding the laminate is impregnated with an ethylene glycol-adipic acid paste as a driving electrolyte. , rated 25V, DC
, -220 μF electrolytic capacitor (B) was manufactured.

Therefore, the electrolytic capacitor (A) in Example 1 according to the present invention is different from the electrolytic capacitor (A) in Comparative Example 1, which is a conventional method.
Compared to B), the volume ratio can be reduced by about 20%, which contributes to miniaturization.

Further, in the method of Example 1, the winding operation was simple because the anode foil and the cathode foil were simply laminated together and the laminate was wound, and the winding efficiency was also significantly improved.

Next, as a result of investigating the capacitance change rate and tan δ with respect to temperature and the frequency-impedance characteristics of the electrolytic capacitor (A) of the example and the electrolytic capacitor (B) of the comparative example, the results are shown in FIGS. 7 to 9. The result was as shown.

As is clear from FIGS. 7 to 9, the electrolytic capacitor (A) of the example is more stable than the electrolytic capacitor (B) of the comparative example in all characteristics.

〔Effect of the invention〕

According to the present invention, the photosensitive film formed on the anode and cathode foils is photocured using active light that passes through a negative or positive film on which many fine patterns are formed, and then developed. , a large number of fine protrusions are precisely arranged and formed on the Yang Yin Toki foil, or a microporous membrane having a large number of through holes is formed, and the method is an extremely reproducible method, This is a method that allows the precise formation of the large number of minute protrusions or the microporous membrane, and as a result, using an anode and cathode foil on which the large number of minute protrusions or the microporous membrane are arranged. Therefore, without using any paper spacers, it is possible to easily manufacture an electrolytic capacitor with good characteristics and high practical value that contributes to miniaturization, weight reduction, and cost reduction.

[Brief explanation of drawings]

1 to 5 are explanatory diagrams for explaining the manufacturing method of the present invention, in which FIG. 1 is a perspective view showing a capacitor element partially rewound, and FIG. FIG. 3 is a partially enlarged perspective view showing the cathode foil with a film formed thereon, and FIG. FIG. 4 is a partially enlarged perspective view of a cathode foil with many fine protrusions formed on both sides, and FIG. 5 is a perspective view showing a cathode foil with many fine protrusions formed on both sides. FIG. 3 is a vertical cross-sectional view showing a part of the cathode foil on an enlarged scale. Further, FIG. 6 is a partially enlarged perspective view showing a cathode foil in which a microporous film having a large number of N1IIl holes is formed on both sides using a negative film having a pattern opposite to that shown in FIG. Further, FIG. 7 is a temperature-capacitance change rate characteristic curve diagram, FIG. 8 is a temperature-tan δ characteristic curve diagram, and FIG. 9 is a frequency-impedance characteristic curve diagram. 1: Cathode foil, 2: Photosensitive film, 3: Transparent part of negative film, 4: Negative film, 5: Exposed surface of cathode foil, 5゛: N hole, 6: Fine protrusion, 6゛: Fine Porous membrane, 7; anode foil, 8; capacitor element. Patent applicant Ube Industries, Ltd. Marcon Electronics Co., Ltd. Hyman Parts Co., Ltd. Figure 1 Figure 5 Figure 6 Figure 6' Frequency (in Hz)

Claims (1)

[Claims] A solution of a photosensitive aromatic polymer is applied to both surfaces of one or both of an anode foil and a cathode foil made of a valve metal and dried to form a photosensitive film, and then, On the photosensitive film formed on the surface of the foil, a negative or positive film having a large number of fine patterns is closely overlaid, and a portion of the photosensitive film is photocured by irradiation with light. , after removing said negative or positive film,
The unphotocured portion of the photosensitive film is removed with a developer and developed to expose the surface of the foil, forming a large number of fine projections or a large number of penetrations made of the photocured layer on the surface of the foil. A microporous film consisting of a photocured layer having holes is formed, and finally, the anode foil and the cathode foil are stacked on top of each other so that the protrusions or the microporous film are present between the anode foil and the cathode foil, and the lamination is performed. A method for manufacturing an electrolytic capacitor, which comprises: winding a body to form a capacitor element, and impregnating the capacitor element with a driving electrolyte.