TWI685865B - Manufacturing method of electrolytic capacitor - Google Patents

Abstract

[Problem] The present invention is to provide an electrolytic capacitor in which a metal case is coated with a polyester resin excellent in adhesion between a resin layer capable of suppressing peeling even when fastened and metal.

[Technical content] An electrolytic capacitor, which contains a capacitor element and a sealing member in a metal case, is sealed by fastening the side surface and opening end surface of the metal case, the metal case is formed with a polyester resin layer on the outer surface , By making the thickness of the metal shell on the side surface fastened to 1/2 or more of the thickness of the metal shell on the bottom surface, the peeling of the polyester resin layer from the metal shell can be suppressed, and high reliability in ensuring insulation can be achieved Electrolytic capacitor.

Description

Manufacturing method of electrolytic capacitor

The present invention relates to an electrolytic capacitor for improving a metal shell used as a shell for external equipment and a method for manufacturing the same.

In a conventional electrolytic capacitor, an anode foil and a cathode foil are wound through a separator to form a capacitor element, and the capacitor element is accommodated in a metal case such as aluminum by being impregnated with a driving electrolyte. The open end is sealed by a sealing member to form an electrolytic capacitor.

In order to achieve the insulation of the metal shell of the electrolytic capacitor, there has been a phenomenon in which a shrink tube such as polyvinyl chloride resin is used to cover the electrolytic capacitor, but the phenomenon of deterioration due to the influence of the shrink tube during high-temperature reflow soldering.

It has also been reviewed to replace this shrinkable tube, and a metal plate (aluminum plate) which is a material of a metal shell is coated with a resin layer to form a metal shell by drawing processing (Patent Document 1). However, when the adhesion between the resin layer and the aluminum surface in the metal shell coated with this resin is poor, the resin layer will peel off from the aluminum surface during the sealing process of the metal shell, that is, the fastening process. The resin layer of the metal shell is mainly responsible for the insulation of the metal shell of the electrolytic capacitor, but If it is peeled off from the metal plate, pinholes are likely to occur in the resin layer, and the insulation may decrease.

[Conventional Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 9-275043

Here, the present invention provides an electrolytic capacitor and a method for manufacturing the same, using a polyester-coated metal shell excellent in adhesion between a polyester resin layer that can suppress peeling even when fastened and a metal.

In order to achieve the foregoing object, the electrolytic capacitor of the present invention is to accommodate the capacitor element and the sealing member in a metal case in which a polyester resin layer is formed on the outer surface of the metal plate, and the side surface and opening end surface of the metal case are fastened to seal It is characterized in that the aforementioned metal shell is provided with a polyester resin layer on its outer back surface, and the thickness of the metal shell on the tightened side is made 1/2 or more of the thickness of the metal shell on the bottom surface.

In addition, the inner circumferential diameter of the metal shell on the tightened side is in the range of 85 to 95% of the inner circumferential diameter of the metal shell on the unfastened side.

And the polyester resin layer on the side of the metal shell that is fastened is exposed to a temperature above 100°C even after the metal shell is tightened It will not peel off.

In addition, the method for manufacturing an electrolytic capacitor of the present invention is to accommodate a capacitor element and a sealing member in a metal case, and to seal by fastening the side surface and the opening end surface of the metal case, characterized in that the metal case is on its outer surface A polyester resin layer is provided, and the thickness of the metal shell on the side surface to be fastened is set to be 1/2 or more of the thickness of the metal shell on the bottom surface.

In addition, the aforementioned metal shell is subjected to a heat treatment to make the temperature of the outer surface of the metal shell 140 to 200°C before tightening.

According to the electrolytic capacitor of the present invention and the manufacturing method thereof, any of the following effects can be obtained.

(1) By controlling the thickness of the side surface of the metal shell due to tightening, the adhesion between the metal shell and the resin layer can be improved, and peeling of the resin layer after tightening can be suppressed. By suppressing peeling of the resin layer, the insulation of the metal case is ensured, and an electrolytic capacitor with high reliability can be realized.

(2) By controlling the size of the fastening portion of the side surface of the metal shell due to tightening, the metal shell and the resin layer and peeling can be suppressed.

(3) By performing heat treatment before tightening, the adhesion between the metal shell and the resin layer can be improved, and peeling of the resin layer after tightening can be suppressed.

(4) Even after being exposed to a hot atmosphere (such as aging treatment or high-temperature reflow soldering) after the metal shell is tightened, the resin Layer peeling.

1‧‧‧Electrolytic capacitor

2‧‧‧Capacitor element

3‧‧‧Metal shell

4‧‧‧Sealing member

5‧‧‧lead terminal

6‧‧‧Polyester resin layer

7‧‧‧Open end fastening section

8‧‧‧Side fastening part

9‧‧‧Layered body

10‧‧‧Aluminum plate

11‧‧‧Stripping Department

[Figure 1] A diagram showing an example of a capacitor element before housing storage of an example.

[Figure 2] A diagram showing the manufacturing process of the metal shell, (a) is a metal plate covered with a resin layer before drawing, and (b) is a diagram showing the metal shell.

[Figure 3] A cross-sectional view showing a manufacturing process of a conventional electrolytic capacitor.

[FIG. 4] A cross-sectional view showing the manufacturing process of the electrolytic capacitor of the embodiment.

[Fig. 5] A cross-sectional view showing a metal case of the electrolytic capacitor of the embodiment.

The form for implementing the electrolytic capacitor of the present invention will be described below based on the examples.

[Example]

The electrolytic capacitor 1 of the embodiment will be described with reference to FIGS. 1 to 5. As shown in FIG. 1, the electrolytic capacitor 1 of the embodiment includes a capacitor element in which an anode foil and a cathode foil are wound through a separator 2, and a bottomed cylindrical metal case 3 that houses the capacitor element 2 and the electrolyte, and a sealing member 4 that seals the metal case 3.

The anode foil is made of valve-acting metal such as aluminum, and the surface is roughened by etching treatment, and an oxide film layer is formed on the surface. The cathode foil is made of valve-acting metal such as aluminum like the anode foil, and the surface is roughened by etching treatment. In these bipolar electrodes, the lead terminal 5 on the anode side of aluminum or the like, and the lead terminal 5 on the cathode side of aluminum or the like are electrically connected by connection methods such as sewing, cold welding, and ultrasonic welding. This lead-out terminal 5 is provided with: a flattened portion connected to the electrode foil and a lead-out portion (CP line) for external connection; and a strip-shaped body, one of which is connected to the electrode foil and the other is connected to The external terminal connector of the additional sealing member 4 for external extraction.

The separator between the anode foil and the cathode foil is electrically insulating, consisting of: Manila hemp paper, kraft paper, thatched paper, hemp paper, hemp paper, cuprammonium fiber, rayon, cotton or mixed paper of these, or synthetic It is composed of fiber and non-woven fabric or mixed paper of these.

In the capacitor element 2, the driving electrolyte and solid electrolyte as the electrolyte are contained in the capacitor element and housed in a bottomed cylindrical metal case 3 made of aluminum or the like. The opening of the metal case 3 is borrowed The sealing member 4 made of an elastic material such as rubber (for example, butyl rubber) is tightly sealed. In the sealing, the metal case 3 and the sealing member 4 are closely adhered by the fastening part 7 on the opening end surface of the metal case 3 and the fastening part 8 on the side surface of the metal case 3 to seal the electrolytic capacitor 1.

The driving electrolyte can be used for electrolytic capacitors Some driving electrolytes include, for example, γ-butyrolactone, ethylene glycol, cyclobutane, dimethylformamide, water, and mixed solvents of those. The solutes are, for example, organic acids, inorganic acids and salts, and examples include ammonium salts, quaternary ammonium salts, quaternary salt salts, and amine salts.

The solid electrolyte is an existing conductive polymer that can be used for solid electrolytic capacitors, and examples thereof include polythiophene, polypyrrole, polyaniline, and derivatives of those. In particular, 3,4-vinyldioxythiophene, 3-alkylthiophene, 3-dialkoxythiophene, 3-alkyl-4-dialkoxythiophene, 3,4-alkylthiophene, 3, 4-Dialkoxythiophene is the best.

The metal shell 3 is, as shown in FIG. 2(a), a laminate 9 in which a polyester resin layer 6 is formed on the surface of a metal plate (aluminum plate 10) made of a metal material such as aluminum, as shown in FIG. 2(b) As shown, by drawing this laminate 9 from the metal plate side, a bottomed cylindrical metal shell 3 provided with a polyester resin layer 6 can be formed on the outer surface.

The aluminum plate 10 means a plate-like body of pure aluminum or aluminum alloy, and specific examples include a plate-like shape of a pure aluminum-based 1000 series, an AL-Mn-based 3000 series alloy, and an AL-Mg-based 5000 series alloy. body. These aluminum plates 10 are not limited to those exemplified. In particular, considering the coating properties of the polyester resin, those of 1000 series or 3000 series are preferable.

The thickness of the aluminum plate 10 is preferably 0.1 to 1 mm, and more preferably 0.2 to 0.8 mm. If it is thinner than 0.1 mm, it becomes difficult to cover the polyester resin. On the other hand, if it is thicker than 1 mm, the drawability deteriorates.

The aluminum plate 10 may be subjected to various tempering treatments and pre-treatments such as solution treatment and aging treatment. Although the above pretreatment is not special It is not limited, but it is possible to remove the oil adhering to the surface of the aluminum plate 10, and it is preferable to remove the coating of the uneven oxide on the surface. For example, after degreasing treatment with a weakly alkaline resin solution is applied, it can be suitably used: after alkaline etching with sodium hydroxide aqueous solution, decontamination treatment with nitric acid aqueous solution; and acid after degreasing treatment Washing treatment, etc. Furthermore, aggressive etching at the same time as degreasing may roughen the surface of the aluminum plate 10 without coloring, so as to improve the anchor effect, and may also have a flat surface that is not roughened.

The polyester resin coated on the aluminum plate 10 is exemplified by: Taking polyethylene terephthalate and ethylene terephthalate units as the main body, the copolymerization component is isophthalic acid, naphthalene dicarboxylic acid or neopentyl glycol, which is also a copolymerized polyester A film composed of polyester, polyethylene naphthalene, and a composite resin containing these butylene terephthalate units as the main unit, particularly polyethylene terephthalate, is preferred.

In addition, in the polyester resin layer 6, it can be added as needed Additives such as stabilizers, oxidation inhibitors, charge inhibitors, pigments, slip agents, corrosion inhibitors, etc.

The thickness of the polyester resin layer 6 is 3μ~100μm Better, better is 5~15μm. When the thickness is less than 3 μm, it is very difficult to laminate the polyester resin layer 6 uniformly. Furthermore, when the obtained resin-coated aluminum plate 10 is deep-drawn, cracks are easily generated in the resin layer, and the corrosion resistance and electrical insulation are remarkable Deteriorated situation. On the other hand, when it exceeds 100 μm, it is economically disadvantageous.

The polyester resin-coated aluminum plate 10 of the present invention (laminate 9) The production method is not particularly limited, but it can be achieved by thermally fusing the polyester resin film-formed in advance by a layer roller to a furnace, induction heating roller, heating medium heating roller, etc. A method of heating the aluminum plate 10 to a temperature above the melting point of the polyester resin; or a method of extruding the heated and melted polyester resin onto the aluminum plate 10 and forming it by a known method.

Process of forming and forming aluminum plate 10 covered with polyester resin The degree makes the adhesion insufficient, and depending on the use environment, the corrosion resistance may be insufficient. In this case, between the polyester resin and the aluminum plate 10, a primer layer such as an organic silane coupling agent layer having a functional group such as an amine group, an epoxy group, an acrylic group, etc., and an acrylic group, a urethane Adhesive layers of functional groups such as epoxy groups, epoxy groups, polyester groups, etc., or stacked in between, can obtain required workability and corrosion resistance.

In order to make the metal shell 3 dense by deep drawing If it is sealed and fastened, since the deformability of the surface of the aluminum plate 10 constituting the aluminum plate 10 of the metal shell 3 is not good, the adhesion between the polyester resin layer 6 and the aluminum plate 10 will be affected during tightening. During this tightening, the polyester resin layer 6 is not easily peeled off from the aluminum plate 10. When the subsequent aging process and the mounting process of the electrolytic capacitor 1, that is, the reflow soldering process, are exposed to a temperature atmosphere exceeding 100 degrees, the polymer The ester resin layer 6 may have a problem of peeling from the aluminum plate 10.

As shown in Figure 3, the metal shell 3 to be drawn If the side is fastened, the side aluminum plate 10 will extend toward the inside and its thickness will gradually decrease. The polyester resin layer 6 coated on the side of the metal shell 3 is also elongated, which affects the aluminum plate 10 and the polyester resin layer 6 on the side Of adhesion. This is because the aluminum plate 10 on the side of the metal shell 3 is elongated by the fastening 8, and the smaller the thickness, the greater the influence on the adhesion. In such a situation, when exposed to a temperature atmosphere exceeding 100 degrees, the elongated polyester resin aggregates to produce a peeling portion 11 and expose the aluminum plate 10 to the side of the metal shell 3.

Here, as a result of the in-depth review, the inventors found that: By controlling the thickness of the fastening portion 8 on the side of the elongated metal shell 3, peeling of the polyester resin layer 6 from the metal plate can be suppressed. That is, as can be seen from FIG. 4, the thickness (T2) of the aluminum plate 10 of the fastening portion B on the side of the metal shell 3 is made 1/1/the thickness (T1) of the aluminum plate 10 on the bottom surface of the metal shell 3 2 or more, the peeling of the polyester resin layer 6 can be suppressed. The metal shell 3 is a deep drawing process of the laminate 9 of the aluminum plate 10 and the polyester resin layer 6, and the thickness (T1) of the bottom surface and the thickness (T2) of the side surface of the aluminum plate 10 vary depending on the height of the metal shell 3. The higher the shell size, the smaller the thickness (T2) of the aluminum plate 11 on the side, and the difference between the thickness (T1) of the bottom and the thickness (T2) of the side increases. In particular, when the height dimension of the metal shell 3 is larger than the diameter dimension of the metal shell 3, the side surface of the metal shell 3 extends more. In this state, by tightening the side surface, the side surface of the metal shell 3 is fastened The thickness (T2) is further reduced, and the polyester resin layer 6 is insufficiently tracked, and is easily peeled. That is, the thickness (T1) of the aluminum plate 10 on the bottom surface of the metal shell 3 and the thickness (T2) of the aluminum plate 10 of the fastening portion 8 on the side surface are related, and are set to a specific range, that is, by setting the side surface When the thickness (T2) of the fastening portion 8 is made to be 1/2 or more of the thickness (T1) of the bottom surface, the peeling of the polyester resin layer 6 can be suppressed. Fastening 8 thick The degree is the part of the metal plate (aluminum plate 10) that is thinned by being fastened on the side of the metal shell 3, that is, the part with the thinnest thickness.

And in order to suppress the polyester resin layer 6 from the metal plate (aluminum plate 10) Peeling, the tightening depth of the side of the metal shell 3 can be checked. Normally, the fastening part 8 on the side is fastened by contacting the top surface of the disc-shaped fastening surface with the side of the metal shell 3, but by controlling the fastening depth, the polyester resin layer 6 can be suppressed Peel from the aluminum plate 10. That is, as shown in FIG. 4, the inner circumferential diameter (T4) of the fastening portion 8 on the side surface of the metal shell 3 is set to a range of 85 to 95% of the inner circumferential diameter (T3) of the metal shell 3 that is not fastened. It is possible to reduce the extension of the side surface of the metal case 3 to suppress the peeling of the polyester resin layer 6 and maintain the sealing performance of the electrolytic capacitor 1.

And further in order to suppress the polyester resin layer 6 from the metal plate (Aluminum plate 10) After peeling, the bottomed cylindrical metal shell 3 after drawing is heat-treated in a high-temperature atmosphere so that its outer surface becomes 140 to 200°C. As shown in FIG. 5, the aluminum plate 10 having the polyester resin layer 6 formed on the surface is formed by drawing to form a cylindrical metal shell 3 having a bottom. This metal shell 3 is heat-treated in a high-temperature atmosphere so that its outer surface becomes 140 to 200°C. For example, the metal shell 3 is placed in a high-temperature bath in a high-temperature atmosphere, and heat treatment is performed so that the temperature of the outer surface of the metal shell 3 becomes 140 to 200°C. The heat treatment time is preferably a treatment time of 30 minutes or more in the range of the temperature of the outer and back surfaces of the metal shell 3 in the range of 140 to 200°C. By this heat treatment, the state in which the side surface of the metal shell 3 is extended by drawing and the polyester resin layer 6 following it is elongated is relaxed, and it becomes the state of being in close contact with the metal shell 3 again. Because of this improved adhesion, even if it becomes the metal of the sealing process The fastening part 8 on the side of the shell 3 is stronger, and is exposed to the high temperature atmosphere (aging treatment and reflow soldering process, etc.) thereafter, and the polyester resin layer 6 will not peel off from the aluminum plate 10, which can ensure the metal shell 3 Insulation. In addition, if the temperature of the heat treatment is less than 140°C, the adhesion between the polyester resin layer 6 and the aluminum plate 10 is not improved, and if it exceeds 200°C, the polyester resin layer 6 itself deteriorates and affects insulation.

As described above, in the electrolytic capacitor 1 of the embodiment, the adhesion between the polyester resin layer 6 and the metal plate (aluminum plate 10) can be improved, and even after being exposed to a hot atmosphere after the fastening of the side of the metal shell 3, the polyester Even if the resin layer 6 is not peeled off, insulation can be ensured, and the electrolytic capacitor 1 with high reliability can be realized.

1‧‧‧Electrolytic capacitor

2‧‧‧Capacitor element

3‧‧‧Metal shell

4‧‧‧Sealing member

5‧‧‧lead terminal

7‧‧‧Open end fastening section

8‧‧‧Side fastening part

Claims (3)

A method of manufacturing an electrolytic capacitor is a method of manufacturing an electrolytic capacitor in which a capacitor element and a sealing member are accommodated in a metal case, and the side surface and the opening end surface of the metal case are fastened and sealed, and polyester is formed on the surface of the metal plate The laminate of the resin layer is drawn from the side of the metal plate so that the height dimension is greater than the diameter dimension, and a bottomed cylindrical metal case provided with a polyester resin layer on the outer surface is formed; the capacitor element and the sealing member are housed Before the metal shell is tightened, a heat treatment is applied so that the temperature of the outer surface of the metal shell becomes 140 to 200°C; the thickness of the metal shell on the side of the tightening is set to the thickness of the metal shell on the bottom Tighten by 1/2 or more. The method for manufacturing an electrolytic capacitor according to item 1 of the patent application range, wherein the inner circumferential diameter of the metal shell on the tightened side is in the range of 85 to 95% of the inner circumferential diameter of the metal shell on the unfastened side. The method for manufacturing an electrolytic capacitor according to claim 1 or claim 2, wherein the polyester resin layer on the side of the metal shell to be fastened is exposed to a temperature of 100°C or higher after the metal shell is tightened Will not peel off.

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