JP7593371B2 - Electrolytic capacitor and method for manufacturing the same - Google Patents

Description

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

Patent document 1 discloses a solid electrolytic capacitor in which the exterior body that covers the element contains an inorganic filler.

Patent Document 2 also discloses that the molded exterior resin of a chip-type solid electrolytic capacitor contains spherical fillers and crushed fillers.

JP 2011-003827 A JP 2009-176973 A

The exterior body protects the capacitor element from thermal load and oxidation during reflow, and also protects the capacitor element from dirt and condensation.
In addition, the exterior body also serves to block oxygen and water vapor in the atmosphere during actual use after mounting, thereby contributing to improving the reliability of the electrolytic capacitor.

Here, in order to increase the capacitance of the electrolytic capacitor, it is preferable to reduce the volume occupied by the exterior body and increase the volume occupied by the capacitor element.
However, making the exterior body smaller reduces the thickness of the exterior body, which reduces its strength. If the exterior body is not strong enough, when the electrolytic capacitor is exposed to a high-temperature environment during reflow, the exterior body cannot withstand the increase in internal pressure caused by vaporized moisture, and cracks occur in the exterior body.

Cracks that occur in the exterior body propagate through the exterior body, penetrating and exposing the exterior body's outer surface. If cracks are present in the exterior body, moisture and oxygen will penetrate into the interior of the exterior body through the cracks when the electrolytic capacitor is used after reflow, accelerating the deterioration of the internal capacitor elements and causing deterioration of the electrical characteristics of the electrolytic capacitor. Therefore, preventing cracks from being exposed on the exterior body's outer surface will improve the reliability of the electrolytic capacitor.

Therefore, as shown in Patent Documents 1 and 2, a material in which a resin contains a filler is used as the exterior body of a capacitor element, and attempts have been made to increase the strength of the exterior body by including a filler in the resin.
However, the methods described in Patent Documents 1 and 2 do not sufficiently improve the strength of the exterior body. Moreover, from the viewpoint of suppressing an increase in manufacturing costs, it is not enough to simply increase the amount of filler contained.
Therefore, there has been a demand for improving the strength of the exterior body by a method different from the methods described in Patent Documents 1 and 2.

The present invention has been made to solve the above problems, and aims to provide an electrolytic capacitor with excellent reliability. Furthermore, the present invention aims to provide a manufacturing method for an electrolytic capacitor that can realize an electrolytic capacitor with excellent reliability.

The electrolytic capacitor of the present invention has a rectangular resin molded body including a stack in which a plurality of capacitor elements, each of which includes an anode having a dielectric layer on its surface and a cathode facing the anode, are arranged along a first direction, and an exterior body that seals the periphery of the stack, and the resin molded body has a first main surface and a second main surface that face each other in the first direction, a first end surface and a second end surface that face each other in a second direction perpendicular to the first direction and expose the cathode and the anode, and a first side surface and a second side surface that face each other in a third direction perpendicular to the first direction and the second direction, and the exterior body contains insulating fibers, and the insulating fibers are oriented in the third direction and/or the first direction.

The method for manufacturing an electrolytic capacitor of the present invention includes a step of preparing a stack in which a plurality of capacitor elements, each of which includes an anode having a dielectric layer on its surface and a cathode facing the anode, are arranged along a first direction, and a sealing step of sealing the stack with an exterior body. In the electrolytic capacitor to be manufactured, when the direction perpendicular to the first direction and in which the anode and the cathode face each other is defined as a second direction, and the direction perpendicular to the first direction and the second direction is defined as a third direction, in the sealing step, a resin composition containing a resin and insulating fibers is caused to flow along a direction that is the third direction or the first direction of the electrolytic capacitor to be manufactured.

According to the present invention, it is possible to provide an electrolytic capacitor with excellent reliability. Furthermore, according to the present invention, it is possible to provide a manufacturing method for an electrolytic capacitor that can realize an electrolytic capacitor with excellent reliability.

FIG. 1 is a perspective view illustrating an example of an electrolytic capacitor according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line XX of the electrolytic capacitor shown in FIG. FIG. 3 is a cross-sectional view that illustrates an example of a capacitor element included in the electrolytic capacitor illustrated in FIG. FIG. 4 is a perspective view showing a schematic example of a crack occurring in an exterior body. FIG. 5 is a perspective view showing a schematic example of a crack occurring in an exterior body. FIG. 6 is a schematic diagram showing an example of the orientation of insulating fibers in an exterior body that constitutes the main surface of a resin molded body. FIG. 7 is a schematic diagram showing an example of the orientation of the insulating fibers when the resin molding (outer housing) is viewed from a second direction. FIG. 8 is a schematic diagram showing an example of the orientation of insulating fibers in an exterior body that constitutes a side surface of a resin molded body. FIG. 9 is a schematic diagram showing an example of the orientation of the insulating fibers when the resin molding (outer housing) is viewed from the second direction. FIG. 10 is a schematic diagram showing an example of the orientation of the insulating fibers when the resin molding (outer housing) is viewed from the second direction. FIG. 11 is a perspective view that illustrates an example of a first portion of an exterior body used in the method for manufacturing an electrolytic capacitor according to an embodiment of the present invention. FIG. 12 is a plan view that illustrates an example of a process for manufacturing the first portion of the exterior body illustrated in FIG. FIG. 13 is a front view of the step shown in FIG. FIG. 14 is a plan view illustrating a schematic diagram of another example of a process for manufacturing the first portion of the exterior body illustrated in FIG. FIG. 15 is a right side view of the step shown in FIG. FIG. 16 is a plan view illustrating an example of a workpiece used in the method for manufacturing an electrolytic capacitor according to an embodiment of the present invention. FIG. 17 is a diagram illustrating an example of a step of attaching an adhesive sheet to a first portion of an exterior body. FIG. 18 is a diagram illustrating an example of a process for supplying a conductive paste onto an adhesive sheet. Fig. 19A is a diagram showing an example of a process for preparing a stack of multiple capacitor elements. Fig. 19B is a diagram showing an example of a process for inserting the stack into a through hole. Fig. 19C is a diagram showing an example of a process for embedding a first portion of a tip side of each capacitor element in a conductive paste. Fig. 19D is a diagram showing an example of a process for filling a liquid material into a gap between each capacitor element (stack) inserted into a through hole and a first portion of an exterior body. FIG. 20 is a diagram illustrating an example of a step of cutting the first portion of the exterior body around the through hole.

The electrolytic capacitor and the method for producing the electrolytic capacitor of the present invention will be described below.
However, the present invention is not limited to the following configurations, and can be modified and applied as appropriate within the scope of the present invention. Note that the present invention also includes a combination of two or more of the individual desirable configurations described below.

[Electrolytic capacitor]
Fig. 1 is a perspective view showing an example of an electrolytic capacitor according to an embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line XX of the electrolytic capacitor shown in Fig. 1. Fig. 3 is a cross-sectional view showing an example of a capacitor element included in the electrolytic capacitor shown in Fig. 1.

As shown in FIG. 1, the electrolytic capacitor 100 has a substantially rectangular parallelepiped outer shape. The electrolytic capacitor 100 includes a rectangular parallelepiped resin molded body 110, a first external electrode 120, and a second external electrode 130.

1 and 2, the second direction of the electrolytic capacitor 100 and the resin molded body 110 is indicated by L, the third direction by W, and the first direction by T. Here, the second direction L, the third direction W, and the first direction T are mutually perpendicular. The direction in which the multiple capacitor elements included in the electrolytic capacitor 100 are arranged in a stacked manner is referred to as the first direction. When multiple capacitor elements are stacked, the first direction is also referred to as the stacking direction. The direction perpendicular to the first direction, in which the anode and cathode of the electrolytic capacitor face each other, is referred to as the second direction. The second direction is also referred to as the length direction. The direction perpendicular to the first and second directions is referred to as the third direction. The third direction is also referred to as the width direction.

The resin molded body 110 has a rectangular parallelepiped shape. The resin molded body 110 has a first main surface 110a and a second main surface 110b that face each other in a first direction T, a first side surface 110c and a second side surface 110d that face each other in a third direction W, and a first end surface 110e and a second end surface 110f that face each other in a second direction L.

As described above, the resin molded body 110 has a rectangular parallelepiped outer shape, but the corners and ridges may be rounded. A corner is a portion where three faces of the resin molded body 110 intersect, and a ridge is a portion where two faces of the resin molded body 110 intersect.

The resin molded body 110 includes a capacitor element 10 and a stack 11 in which a plurality of capacitor elements 10 are arranged along a first direction. The resin molded body 110 further includes an exterior body 20 that seals the periphery of the stack 11, and a collecting electrode 30.
The number of capacitor elements 10 included in stack 11 is not particularly limited as long as it is two or more, and can be set appropriately.
In addition, the term "superimposed body" in this specification may be obtained by subjecting capacitor elements to a "stacking step" in the manufacturing process described below, or may be obtained without subjecting the capacitor elements to a "stacking step." A "superimposed body" is defined as a body in which capacitor elements are arranged in a certain direction (this direction is referred to as a first direction) as components of an electrolytic capacitor.
The cathode 43 of the capacitor element 10 is exposed at a first end surface 110e of the resin molded body 110, and the anode 40 of the capacitor element 10 is exposed at a second end surface 110f.

The exterior body 20 seals the plurality of capacitor elements 10. That is, a stack 11 of the plurality of capacitor elements 10 is embedded in the exterior body 20. The exterior body 20 also seals the collecting electrodes 30.
The exterior body 20 shown in FIG. 2 has a first portion 21 containing a first resin material and a second portion 22 containing a second resin material.

The first part 21 is a tubular structure having a through hole 23, and multiple capacitor elements 10 (superimposed body 11) are housed in the through hole 23. The second part 22 exists in the through hole 23 that houses the multiple capacitor elements 10 (superimposed body 11).

The configuration of the capacitor element and the configuration of the laminate will be described with reference to FIG. 2 and FIG.
Each capacitor element 10 includes an anode 40 which is a thin film (foil) having a rectangular shape in plan view and which is made of a porous valve metal base and has a substantially flat surface, a dielectric layer 41 (see FIG. 3, not shown in FIG. 2) provided on the surface of the anode 40 except for the base end surface 40b of the anode 40, a mask layer 42 which is a linear (extending in a strip-like shape) insulating member provided on the dielectric layer 41 along the base end surface 40b of the anode 40, and a cathode 43 provided on the dielectric layer 41 on the side of the mask layer 42 that is closer to the tip end surface 40a of the anode 40. In each capacitor element 10, the cathode 43 faces the anode 40 via the dielectric layer 41.

Here, each cathode 43 is part of the cathode of the electrolytic capacitor 100, and each anode 40 is part of the anode of the electrolytic capacitor 100. That is, the stack 11 of multiple capacitor elements 10 includes multiple cathodes 43 as multiple first internal electrodes and multiple anodes 40 as multiple second internal electrodes.

The anode 40 extends between the first end face 110e and the second end face 110f of the resin molded body 110, and has a first portion 40c on the first end face 110e side and a second portion 40d on the second end face 110f side.

The cathode 43 extends between the first end surface 110e and the second end surface 110f of the resin molded body 110, and has a first portion 43a on the first end surface 110e side and a second portion 43b on the second end surface 110f side. The cathode 43 also has a solid electrolyte layer 44 provided on the dielectric layer 41, a carbon layer 45 provided on the solid electrolyte layer 44, and a cathode conductor layer 46 provided on the carbon layer 45.

As shown in FIG. 2, the collecting electrode 30 is electrically connected to the multiple cathodes 43 of the multiple capacitor elements 10. The collecting electrode 30 is exposed to the first end surface 110e of the resin molded body 110, and is provided at least on the portion of the resin molded body 110 on the first end surface 110e side. The collecting electrode 30 is formed in a shape with a thickness at a position recessed from the first end surface 110e (end surface 21c of the first portion 21).

As shown in FIG. 2, at least the first portion 43a of each cathode 43 is embedded in the collector electrode 30, thereby ensuring electrical connection between each cathode 43 and the collector electrode 30.

The collecting electrode 30 is preferably a composite material of a conductive component (conductive material) and a resin component (resin material). The conductive component preferably contains, as a main component, a metal such as silver, copper, nickel, or tin, or an alloy containing at least one of these metals. The resin component preferably contains, as a main component, an epoxy resin, a phenolic resin, or the like. The collecting electrode 30 can be formed, for example, using a conductive paste such as silver paste.

As shown in FIG. 2, the first external electrode 120 is provided on the first end surface 110e of the resin molding 110. In FIG. 1, the first external electrode 120 is provided from the first end surface 110e of the resin molding 110 to each of the first main surface 110a, the second main surface 110b, the first side surface 110c, and the second side surface 110d. The first external electrode 120 is electrically connected to the collector electrode 30 exposed from the resin molding 110 at the first end surface 110e. That is, the first external electrode 120 is electrically connected to each cathode 43 via the collector electrode 30.

In addition, the collecting electrode 30 is present in the through hole 23 that houses the multiple capacitor elements 10 (superimposed body 11), and since the collecting electrode 30 and the first part 21 of the outer casing 20 form the first end surface 110e of the resin molded body 110, the first external electrode 120 can be formed on this first end surface 110e. Therefore, it is easy to electrically connect the first external electrode 120 and the collecting electrode 30, and it is possible to form the first external electrode 120 with a thin thickness.

Specifically, the first external electrode 120 may have a so-called sputtered film formed by a sputtering method. Examples of materials for the sputtered film include Ni, Sn, Ag, Cu, and Au.

The first external electrode 120 may also have a so-called vapor deposition film formed by a vapor deposition method. Examples of materials for the vapor deposition film include Ni, Sn, Ag, and Cu.

In this way, since the first external electrode 120 can be formed from a sputtered film and/or a vapor deposition film, the film thickness of the first external electrode 120 may be thinner than the film thickness of the second external electrode 130. Specifically, the film thickness of the first external electrode 120 is preferably 1 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm or less, and even more preferably 10 μm or more and 30 μm or less.

As shown in FIG. 2, the second external electrode 130 is provided on the second end surface 110f of the resin molding 110. In FIG. 1, the second external electrode 130 is provided from the second end surface 110f of the resin molding 110 to each of the first main surface 110a, the second main surface 110b, the first side surface 110c, and the second side surface 110d. The second external electrode 130 is electrically connected to the second portion 40d of the anode 40 (valve metal base) of the capacitor element 10 exposed from the resin molding 110 at the second end surface 110f. The second external electrode 130 may be directly or indirectly connected to the anode 40 at the second end surface 110f of the resin molding 110.

At least one of the first external electrode 120 and the second external electrode 130 may have a resin electrode layer containing a conductive component and a resin component. The conductive component preferably contains, as a main component, a metal such as silver, copper, nickel, or tin, or an alloy containing at least one of these metals. The resin component preferably contains, as a main component, an epoxy resin, a phenolic resin, or the like. The resin electrode layer can be formed, for example, using a conductive paste such as silver paste.

At least one of the first external electrode 120 and the second external electrode 130 may have a so-called plating layer formed by a plating method. Examples of the plating layer include a zinc-silver-nickel layer, a silver-nickel layer, a nickel layer, a zinc-nickel-gold layer, a nickel-gold layer, a zinc-nickel-copper layer, and a nickel-copper layer. On these plating layers, it is preferable to provide, in order, a copper plating layer, a nickel plating layer, and a tin plating layer (or with the exception of some plating layers).

At least one of the first external electrode 120 and the second external electrode 130 may have both a resin electrode layer and a plating layer. For example, the first external electrode 120 may have a resin electrode layer connected to the collecting electrode 30 and an outer plating layer provided on the surface of the resin electrode layer. The first external electrode 120 may have an inner plating layer connected to the collecting electrode 30, a resin electrode layer provided to cover the inner plating layer, and an outer plating layer provided on the surface of the resin electrode layer. The second external electrode 130 may have a resin electrode layer connected to the anode 40 (valve metal substrate) and an outer plating layer provided on the surface of the resin electrode layer. The second external electrode 130 may have an inner plating layer connected to the anode 40 (valve metal substrate), a resin electrode layer provided to cover the inner plating layer, and an outer plating layer provided on the surface of the resin electrode layer.

The electrolytic capacitor of the present invention is designed to prevent cracks from occurring in the exterior body. Here, cracks that occur in the exterior body will be described with reference to the drawings.
4 and 5 are perspective views each showing a schematic example of a crack occurring in an exterior body.
Figure 4 shows a crack 50a that has occurred in the outer casing that constitutes the first main surface 110a of the resin molding 110, and Figure 5 shows a schematic diagram of a crack 50c that has occurred in the outer casing that constitutes the first side surface 110c of the resin molding 110.
4 is generated along the second direction L. The crack 50c shown in FIG.

When the electrolytic capacitor includes an assembly including a capacitor element and an exterior body that seals the periphery of the assembly, the direction in which cracks occur is often along the second direction L.
In the main surface (first main surface or second main surface) of the resin molded body, cracks are likely to occur along the second direction L when a force that tears the exterior body in the third direction (force in the direction indicated by the double arrow Fw in FIG. 4 ) is applied. In addition, in the side surface (first side surface or second side surface) of the resin molded body, cracks are likely to occur along the second direction L when a force that tears the exterior body in the first direction (force in the direction indicated by the double arrow Ft in FIG. 5 ) is applied.
Furthermore, cracks often occur on the main surface or side surface of the resin molding, but rarely occur on the end surface of the resin molding.
This is presumably because the main surface of the capacitor element is aligned along the second direction L, and therefore the direction of gas generation during reflow tends to be along the second direction L.
Therefore, it is necessary to suppress the occurrence of cracks in the second direction on the main surface or side surface of the resin molded body.
The electrolytic capacitor of the present invention can suppress the occurrence of cracks of this type.

In the electrolytic capacitor of the present invention, the outer casing contains insulator fibers, and the insulator fibers are oriented in the third direction and/or the first direction. When the insulator fibers contained in the outer casing are oriented in the third direction and/or the first direction, the occurrence of cracks in the second direction can be suppressed.

The case where the insulating fibers are oriented in the third direction will be described with reference to Figs.
Fig. 6 is a schematic diagram showing an example of the orientation of the insulator fibers in the exterior body constituting the main surface of the resin molded body. Fig. 6 shows a first main surface 110a of the resin molded body 110, and therefore Fig. 6 is a top view of the resin molded body (exterior body) as seen from a first direction.

Fig. 7 is a schematic diagram showing an example of the orientation of the insulator fibers when the resin molded body (exterior body) is viewed from a second direction. In this specification, "a view of the resin molded body (exterior body) viewed from a second direction" means a cross-sectional view as shown in Fig. 7. It may also be considered as a cross-sectional view of the electrolytic capacitor shown in Fig. 1 cut at a position along line Y-Y.
It should be noted that the internal structure of the capacitor element 10 is omitted in FIG. 7 and in FIGS. 9 and 10 which will be described later.

The exterior body constituting the first main surface 110a and the second main surface 110b of the resin molded body 110 is a first portion 21 of the exterior body. The insulator fibers 60 included in the first portion 21 of the exterior body are oriented in the third direction W.
When the insulation fibers are oriented in the third direction W, it means that when the orientation of the insulation fibers in the outer casing is observed, many of the insulation fibers are observed to be oriented in a specific direction (the third direction W).

When the outer casing is viewed from a first direction, it is preferable that the insulator fibers are oriented in a third direction, and that the acute angle between the orientation direction of the insulator fibers and the third direction is 40° or less for at least 60% of the insulator fibers.
In FIG. 6, an acute angle among the angles formed by the insulating fibers 60 and the third direction W is indicated by θ.
When the exterior body is viewed from a first direction, the angle indicated by θ in FIG. 6 is determined for each of the insulation fibers shown in the photographed microscope image.
Specifically, the surface of the outer casing to be measured is removed by 30 μm using a _YVO4 laser, and three areas of 1 mm x 1 mm are observed in the first portion of the exposed first main surface, and three areas of 1 mm x 1 mm are observed in the first portion of the exposed second main surface, for a total of six locations, to determine the angle between the third direction and the insulator fibers.
It is preferable that the angle between the third direction and the insulator fibers is 40° or less in at least 60% of the insulator fibers. "At least 60%" is determined by calculating the cumulative relative frequency of the angle between the third direction and the insulator fibers for the insulator fibers reflected in a 1 mm x 1 mm field of view of a microscope image to obtain an angle distribution.
In addition, when the outer casing is viewed from the first direction, it is preferable that the insulator fibers are oriented in a third direction, and that the acute angle between the orientation direction of the insulator fibers and the third direction is 20° or less for at least 60% of the insulator fibers.

When the outer casing is viewed from the second direction, it is preferable that the insulator fibers are oriented in a third direction, and that the acute angle between the orientation direction of the insulator fibers and the third direction is 40° or less for at least 60% of the insulator fibers.
This regulation relates to the orientation of the insulator fibers 60 included in the exterior body (first portion 21) of the portion (top and bottom sides in FIG. 7) constituting the main surface (first main surface 110a and second main surface 110b) of the resin molding 110. In FIG. 7, the orientation of the insulator fibers 60 included in the exterior body (first portion 21) of the portion (left and right sides in FIG. 7) constituting the side surface (first side surface 110c and second side surface 110d) of the resin molding 110 is not taken into consideration.
In Fig. 7, the acute angle between the insulator fiber 60 and the third direction W is indicated by θ. The thickness of the first portion may be thinned to about 0.1 mm (100 µm). To measure the orientation direction of the insulator fiber, the surface of the outer casing to be measured is scraped off by 30 µm with a _YVO4 laser, and three areas of 0.1 mm x 1 mm are observed in the first portion on the exposed first end face side, and three areas of 0.1 mm x 1 mm are observed in the first portion on the exposed second end face side, for a total of six locations, to determine the angle between the third direction and the fiber.
The method of measuring the angle is the same as that described with reference to FIG.
In addition, when the outer casing is viewed from the second direction, it is preferable that the insulator fibers are oriented in a third direction, and that the acute angle between the orientation direction of the insulator fibers and the third direction is 20° or less for at least 60% of the insulator fibers.

When the insulator fibers included in the exterior body are oriented in the third direction, it is possible to suppress the occurrence of cracks along the second direction L in the exterior body constituting the main surface (the first main surface or the second main surface) of the resin molded body. In other words, the crack occurrence mode as shown in FIG. 4 is prevented.
The force that causes cracks along the second direction L on the main surface of the resin molding is a force that tears the outer casing in a third direction (a force in the direction indicated by the double arrow Fw in Figure 4), but since the insulator fibers are oriented in the third direction, the tensile strength of the resin material that constitutes the outer casing in the third direction is increased, and the occurrence of cracks along the second direction L on the main surface of the resin molding is suppressed.

Next, a case in which the insulating fibers are oriented in the first direction will be described with reference to FIGS.
Fig. 8 is a schematic diagram showing an example of the orientation of the insulating fibers in the exterior body constituting the side surface of the resin molded body. Fig. 8 shows the first side surface 110c of the resin molded body 110, and therefore Fig. 8 is a side view of the resin molded body (exterior body) as seen from the third direction.

Figure 9 is a schematic diagram showing an example of the orientation of the insulator fibers when the resin molded body (outer body) is viewed from the second direction. Figures 9 and 7 are cross-sectional views taken from the same perspective, but Figure 9 shows an example in which the orientation of the insulator fibers is different from that of the cross-section shown in Figure 7.

The exterior body constituting the first side surface 110c and the second side surface 110d of the resin molded body 110 is a first portion 21 of the exterior body. The insulator fibers 60 included in the first portion 21 of the exterior body are oriented in a first direction T.
When the insulation fibers are oriented in the first direction T, it means that when the orientation of the insulation fibers in the outer casing is observed, many of the insulation fibers are observed to be oriented in a specific direction (the first direction T).

When the outer casing is viewed from a third direction, it is preferable that the insulator fibers are oriented in a first direction, and that the acute angle between the orientation direction of the insulator fibers and the first direction is 40° or less for at least 60% of the insulator fibers.
In Fig. 8, φ denotes an acute angle among the angles formed by the insulator fibers 60 and the first direction T. The method of measuring the angle is the same as the method described with reference to Fig. 6, and the angle formed by the first direction and the insulator fibers is obtained instead of the angle formed by the third direction and the insulator fibers.
In addition, when the outer casing is viewed from a third direction, it is preferable that the insulator fibers are oriented in the first direction, and that the acute angle between the orientation direction of the insulator fibers and the first direction is 20° or less for at least 60% of the insulator fibers.

When the outer casing is viewed from a second direction, it is preferable that the insulator fibers are oriented in a first direction, and that the acute angle between the orientation direction of the insulator fibers and the first direction is 40° or less for at least 60% of the insulator fibers.
This regulation relates to the orientation of the insulator fibers 60 included in the exterior body (first portion 21) of the portion (left and right sides in FIG. 9) constituting the side surface (first side surface 110c and second side surface 110d) of the resin molding 110. In FIG. 9, the orientation of the insulator fibers 60 included in the exterior body (first portion 21) of the portion (top and bottom sides in FIG. 9) constituting the main surface (first main surface 110a and second main surface 110b) of the resin molding 110 is not taken into consideration.
In Fig. 9, φ denotes an acute angle among the angles formed by the insulator fibers 60 and the first direction T. The method of measuring the angle is the same as the method described with reference to Fig. 7, and the angle formed by the first direction and the insulator fibers is obtained instead of the angle formed by the third direction and the insulator fibers.
In addition, when the outer casing is viewed from a second direction, it is preferable that the insulator fibers are oriented in a first direction, and that the acute angle between the orientation direction of the insulator fibers and the first direction is 20° or less for at least 60% of the insulator fibers.

When the insulator fibers included in the exterior body are oriented in the first direction, it is possible to suppress the occurrence of cracks along the second direction L in the exterior body constituting the side surface (first side surface or second side surface) of the resin molding. In other words, the crack occurrence mode as shown in FIG. 5 is prevented.
The force that causes cracks along the second direction L on the side of the resin molded body is a force that tears the outer casing in the first direction (a force in the direction indicated by the double arrow Ft in Figure 5), but since the insulator fibers are oriented in the first direction, the tensile strength of the resin material that makes up the outer casing in the first direction is increased, and the occurrence of cracks along the second direction L on the side of the resin molded body is suppressed.

The insulating fibers contained in the exterior body may be oriented in the third direction and the first direction. This case will be described with reference to FIG.
Fig. 10 is a schematic diagram showing an example of the orientation of the insulator fibers when the resin molding (exterior body) is viewed from a second direction. Fig. 10 is a cross-sectional view taken from the same viewpoint as Figs. 7 and 9, but Fig. 10 shows an example in which the orientation of the insulator fibers is different from that of the cross-sections shown in Figs. 7 and 9.

In Figure 10, the insulating fibers 60 contained in the outer casing (first portion 21) of the portion (the upper and lower edges of Figure 10) that constitutes the main surfaces (first main surface 110a and second main surface 110b) of the resin molding 110 are oriented in the third direction, as in Figure 7.
Also, in Figure 10, the insulating fibers 60 contained in the outer casing (first portion 21) of the portion (the left and right sides of Figure 10) that constitutes the side (first side 110c and second side 110d) of the resin molding 110 are oriented in the first direction, as in Figure 9.

In this embodiment, it is possible to suppress the occurrence of cracks along the second direction L in the exterior body constituting the main surface (first main surface or second main surface) of the resin molded body. It is also possible to suppress the occurrence of cracks along the second direction L in the exterior body constituting the side surface (first side surface or second side surface) of the resin molded body. In other words, both of the crack occurrence modes shown in Figures 4 and 5 are prevented.

When the insulating fibers contained in the exterior body are oriented in the third direction in the portion that constitutes the main surface of the resin molded body, and are oriented in the first direction in the portion that constitutes the side surface of the resin molded body, the insulating fibers contained in the exterior body are considered to be oriented in the third direction and the first direction.

Even when the insulating fibers contained in the outer casing are oriented in the third direction and the first direction, the following aspect is preferable.
When the outer casing is viewed from a first direction, the insulator fibers are oriented in a third direction, and it is preferable that the acute angle between the orientation direction of the insulator fibers and the third direction is 40° or less for at least 60% of the insulator fibers, and more preferably 20° or less.
When the outer casing is viewed from the second direction, the insulator fibers are oriented in a third direction, and it is preferable that the acute angle between the orientation direction of the insulator fibers and the third direction is 40° or less for at least 60% of the insulator fibers, and more preferably 20° or less.

When the outer casing is viewed from the third direction, the insulator fibers are oriented in the first direction, and the acute angle between the orientation direction of the insulator fibers and the first direction is preferably 40° or less for at least 60% of the insulator fibers, and more preferably 20° or less.

When the outer casing is viewed from the second direction, the insulator fibers are oriented in the first direction, and the acute angle between the orientation direction of the insulator fibers and the first direction is preferably 40° or less for at least 60% of the insulator fibers, and more preferably 20° or less.

In addition, it is possible to predict to some extent which side of the resin molding and in which direction the crack will occur by performing a simulation that takes into account the dimensions of the resin molding, the dimensions of the capacitor element, the number of capacitor elements included in the laminate, the thickness of the resin that makes up the outer casing (the thickness of the first part), etc.
Therefore, it is advisable to adjust the orientation direction of the insulator fibers contained in the exterior body so as to prevent cracks from occurring in the surface and direction predicted by the simulation. If cracks are expected to occur on the main surface of the resin molding, it is advisable to orient the insulator fibers in the third direction. If cracks are expected to occur on the side surface of the resin molding, it is advisable to orient the insulator fibers in the first direction.

Although the occurrence of cracks can be prevented by increasing the thickness of the resin constituting the exterior body (the thickness of the first part), increasing the thickness of the resin is disadvantageous in that the size of the parts increases. The thickness of the resin is determined by the size of the parts and the tolerance of the product. In general, it is easy to tolerate increasing the thickness of the resin in the first direction (the thickness of the resin of the exterior body constituting the main surface of the resin molded body), but it is often difficult to increase the thickness of the resin in the third direction (the thickness of the resin of the exterior body constituting the side surface of the resin molded body). From that perspective, it is preferable to be able to prevent cracks occurring on the side surface of the resin molded body without increasing the thickness of the resin of the exterior body. Therefore, it is preferable to orient the insulating fibers contained in the exterior body constituting the side surface of the resin molded body in the first direction, thereby increasing the tensile strength of the resin material constituting the exterior body in the first direction and suppressing the occurrence of cracks along the second direction on the side surface of the resin molded body.

The average fiber length of the insulating fibers contained in the exterior body is preferably 100 μm or more, more preferably 300 μm or more. The average fiber length may be 1000 μm or less, and even better, 700 μm or less. The average fiber length can be defined as the average value of the lengths of the insulating fibers observed within a field of view by microscope observation.
When the average fiber length of the insulating fibers is long, the effect of improving the tensile strength of the exterior body in the orientation direction is high. Since the width of cracks that occur in the exterior body is often about 100 μm, it is preferable to use insulating fibers having an average fiber length of 100 μm or more, which is equal to or greater than the width of the cracks.

The insulating fiber contained in the exterior body is preferably an inorganic fiber, more preferably an amorphous fiber, and further preferably a glass fiber containing a glass component. From the viewpoint of mechanical strength characteristics and insulating properties, glass fiber is preferable.
The insulating fiber preferably contains 50% by weight or more of aluminum oxide or silicon oxide. The insulating fiber may be an alumina fiber, a silica fiber, or an alumina-silica fiber (including mullite fiber). These fibers are preferable because they are particularly excellent in terms of mechanical strength properties. The insulating fiber may be an amorphous fiber containing 50% by weight or more of aluminum oxide or silicon oxide, or may be a glass fiber.

The resin in the portion of the exterior body that contains the insulating fibers (the first resin material that constitutes the first portion) is preferably a thermoplastic resin. The melting point of the thermoplastic resin is preferably 260°C or higher, more preferably 275°C or higher, and even more preferably 300°C or higher. By using such a thermoplastic resin, the strength of the exterior body at high temperatures during reflow can be ensured.

There is no upper limit to the melting point of the thermoplastic resin, but it is usually 400°C or less, preferably 360°C or less, and more preferably 330°C or less.

As the thermoplastic resin, it is preferable to include at least one resin selected from the group consisting of PPS (polyphenylene sulfide), LCP (liquid crystal polymer), PBT (polybutylene terephthalate), polyimide, and polyamide. These resins are suitable as the first resin material because they have high strength at 150°C or higher and can be processed into a tubular shape, which is the shape of the first portion 21, by injection molding, which is a commonly used molding method for thermoplastic resins.

The second resin material constituting the second portion of the exterior body preferably contains at least one type of thermosetting resin selected from the group consisting of epoxy resin, silicone resin, and urethane resin. In the manufacturing method of the electrolytic capacitor described below, since the material is handled at room temperature, a material that is liquid at room temperature before curing is appropriate, and these resins may fall into this category. Furthermore, these resins are also suitable materials as capacitor sealing materials in terms of insulation, heat resistance, etc.

The blending ratio of the insulating fibers in the exterior body is preferably 30% by weight or more, more preferably 45% by weight or more, and is preferably 75% by weight or less, more preferably 60% by weight or less.
The mixing ratio of the insulating fiber contained in the exterior body can be calculated from the weight of the inorganic components remaining after cutting out the exterior body part from the electrolytic capacitor, measuring the total weight, and heating to a temperature equal to or higher than the thermal decomposition temperature of the resin to burn off the resin components, or from the weight of the inorganic components remaining after dissolving and removing the resin in a solvent that dissolves only the resin components.

When the exterior body has a first portion including a first resin material and a second portion including a second resin material, and the first portion has a tubular structure, it is preferable that the first portion includes an insulating fiber. It is also preferable that the blending ratio of the insulating fiber included in the exterior body described above is determined as the weight ratio of the insulating fiber to the weight of the first portion.
When the first portion has a tubular structure, the thickness of the first portion can be reduced by blending insulating fibers oriented in a specific direction. The thickness of the first portion is preferably 200 μm or less, and more preferably 100 μm or less.

By orienting the insulator fibers contained in the first portion of the exterior body that constitutes the main surface of the resin molded body in the third direction, the thickness of the first portion of the exterior body that constitutes the main surface of the resin molded body can be reduced. Therefore, the thickness of the first portion of the exterior body that constitutes the main surface of the resin molded body is preferably 200 μm or less, and more preferably 100 μm or less. In addition, the thickness of the first portion of the exterior body that constitutes the main surface of the resin molded body may be 30 μm or more.

In addition, by orienting the insulating fibers contained in the first portion of the exterior body that constitutes the side surface of the resin molded body in the first direction, the thickness of the first portion of the exterior body that constitutes the side surface of the resin molded body can be reduced. Therefore, the thickness of the first portion of the exterior body that constitutes the side surface of the resin molded body is preferably 150 μm or less, and more preferably 100 μm or less. In addition, the thickness of the first portion of the exterior body that constitutes the side surface of the resin molded body may be 30 μm or more.

In general, since there is often a demand to reduce the thickness of the exterior body constituting the side surface of the resin molded body, it is preferable to make the thickness of the exterior body constituting the side surface of the resin molded body relatively thin. From this viewpoint, it is preferable to make the thickness of the first part of the exterior body constituting the side surface of the resin molded body thinner than the thickness of the first part of the exterior body constituting the main surface of the resin molded body. For example, the ratio of the thickness of the first part of the exterior body constituting the side surface of the resin molded body to the thickness of the first part of the exterior body constituting the main surface of the resin molded body (thickness of the first part of the exterior body constituting the side surface/thickness of the first part of the exterior body constituting the main surface) may be 0.15 or more and 0.75 or less.

The exterior body of the electrolytic capacitor is not limited to an embodiment having the first and second parts, and may be one in which the periphery of the laminate is sealed with a single type of resin. If the resin as the exterior body sealing the periphery of the laminate contains insulating fibers and the insulating fibers are oriented in the third direction and/or the first direction, the occurrence of cracks in the exterior body can be suppressed.
As an exterior body for sealing the periphery of the laminate with a single type of resin, an exterior body for sealing the periphery of the laminate by a method such as transfer molding or compression molding can be used.

[Method of manufacturing electrolytic capacitor]
The method for manufacturing an electrolytic capacitor of the present invention includes the steps of preparing a stack in which a plurality of capacitor elements, each of which includes an anode having a dielectric layer on its surface and a cathode facing the anode, are arranged along a first direction, and sealing the stack with an outer casing, wherein when, in the manufactured electrolytic capacitor, a direction perpendicular to the first direction and in which the anode and the cathode face each other is defined as a second direction, and a direction perpendicular to the first direction and the second direction is defined as a third direction, in the sealing step, a resin composition containing a resin and insulating fibers is caused to flow along a direction which is the third direction or the first direction in the electrolytic capacitor to be manufactured.
An example of the method for producing the electrolytic capacitor of the present invention will now be described.

First, we will explain the process for manufacturing the first part of the exterior body used in the sealing process. The other processes will be described later.

11 is a perspective view showing an example of a first part of an exterior body used in a method for manufacturing an electrolytic capacitor according to an embodiment of the present invention, in which some through holes are seen through.
As shown in FIG. 11, a first portion 221 of an exterior body 220 (a member that becomes the first portion 21 of the exterior body 20) that contains a resin material and has a plurality of through holes 223 is manufactured.
When manufacturing the first portion 221 of the exterior body 220, it is preferable to orient the insulator fibers in a predetermined direction. The method for doing so will be described below.

FIG. 12 is a plan view that illustrates an example of a process for manufacturing the first portion of the exterior body illustrated in FIG. 11, and FIG. 13 is a front view of the process illustrated in FIG.
The first portion 221 is a member in which a flat plate material having a rectangular shape in a plan view and a predetermined thickness is provided with a plurality of through holes 223 vertically and horizontally. Each through hole 223 is provided in a direction perpendicular to the main surface of the first portion 221, and both ends thereof are open.

12 and 13 show the process of manufacturing the first part of the exterior body by injection molding, and show a runner 261 and a gate 262 used in injection molding.
When performing injection molding, a resin composition containing a thermoplastic resin and insulating fibers is poured into a mold (not shown) from a gate 262. The portion of the mold corresponding to the through hole 223 is a portion through which the resin composition does not pass.
Although the gate shown in Figures 12 and 13 is a film gate, the gate may be other types of gates.
As the thermoplastic resin, it is preferable to use at least one resin selected from the group consisting of PPS (polyphenylene sulfide), LCP (liquid crystal polymer), PBT (polybutylene terephthalate), polyimide and polyamide.

The gate direction, which is the direction in which the gate 262 is provided, is the direction in which the resin composition flows, and in Figures 12 and 13, the gate direction is the W direction. This W direction is the third direction W when the electrolytic capacitor is manufactured.
The insulating fibers contained in the resin composition tend to be oriented along the flow direction of the resin composition, and therefore, it is possible to orient the insulating fibers along the gate direction.
12 and 13 are schematic diagrams showing the state in which the insulator fibers 60 are oriented in the W direction. When the insulator fibers are oriented in the W direction in the process of manufacturing the first part of the exterior body, an electrolytic capacitor in which the insulator fibers are oriented in the third direction on the main surface of the resin molded body can be obtained.

14 is a plan view that illustrates another example of a process for manufacturing the first portion of the exterior body illustrated in FIG. 11, and FIG. 15 is a right side view of the process illustrated in FIG.
The shape of the first portion 221 shown in FIG. 14 is similar to the shape of the first portion 221 shown in FIG.
14 and 15 show the process of manufacturing the first part of the exterior body by injection molding, and show a runner 271 and a gate 272 used in injection molding.
When performing injection molding, a resin composition containing a thermoplastic resin and insulating fibers is poured into a mold (not shown) from a gate 272. The portion of the mold corresponding to the through hole 223 is a portion through which the resin composition does not pass.

The gate direction, which is the direction in which the gate 272 is provided, is the direction in which the resin composition flows, and the gate direction is direction T in Figures 14 and 15. This direction T is the first direction T when the electrolytic capacitor is manufactured.
14 and 15 are schematic diagrams showing the state in which the insulator fibers 60 are oriented in the T direction. When the insulator fibers are oriented in the T direction in the process of manufacturing the first part of the exterior body, an electrolytic capacitor in which the insulator fibers are oriented in the first direction on the main surface of the resin molded body can be obtained.

As explained so far, when performing an injection molding process using a thermoplastic resin as the resin, the orientation of the insulator fibers can be adjusted by adjusting the direction in which the resin composition flows. In addition, the orientation of the insulator fibers can also be adjusted by adjusting the injection molding conditions such as the viscosity, temperature, and flow rate of the resin composition, and the shape of the mold, and the orientation of the insulator fibers can also be adjusted by adjusting these conditions. Depending on the adjustment of the injection molding conditions, it is possible to manufacture the first part of the exterior body to obtain a resin molded body in which the insulator fibers are oriented in the third direction and the first direction.

Below, we will explain a method for manufacturing an electrolytic capacitor using the first part of the exterior body manufactured as described above. In the following example, we will explain a method for simultaneously manufacturing multiple capacitor elements using a large valve metal substrate.

Figure 16 is a plan view showing a schematic example of a workpiece used in a method for manufacturing an electrolytic capacitor according to an embodiment of the present invention.

First, as shown in FIG. 16, a workpiece 210 is prepared in which element portions 212 (multiple capacitor elements 10) are connected in strips at regular intervals to a band-shaped holding portion 211.

In detail, first, a valve metal substrate having a porous portion on its surface is cut by laser processing, punching processing, or the like, to form a shape including a plurality of element portions 212 and a holding portion 211.

The valve metal substrate is made of a valve metal such as an elemental metal such as aluminum, tantalum, niobium, titanium, or zirconium, or an alloy containing these metals.
The valve metal base need only be composed of a core and a porous portion provided on at least one of the main surfaces of the core, and may be, for example, a metal foil having an etched surface or a metal foil having a porous sintered powder formed on the surface.

Next, a mask layer is formed on both main surfaces and both side surfaces of each element portion 212 along the short sides of each element portion 212.

The mask layer is formed by applying a mask material such as a composition containing an insulating resin by screen printing, roller transfer, dispenser, inkjet printing, etc. Examples of insulating resins include polyphenylsulfone (PPS), polyethersulfone (PES), cyanate ester resin, fluororesin (tetrafluoroethylene, tetrafluoroethylene-perfluoroalkylvinylether copolymer, etc.), a composition consisting of soluble polyimidesiloxane and epoxy resin, polyimide resin, polyamideimide resin, and derivatives or precursors thereof.

After this, a hydrophilic material may or may not be applied to the mask layer.

Next, an oxide film that will become a dielectric layer is formed on the surface of the valve metal substrate by anodizing the valve metal substrate. For example, the dielectric layer is made of aluminum oxide. At this time, an oxide film is also formed on the side of the element portion 212 that has been cut by laser processing, punching, or the like. Note that a chemical foil on which aluminum oxide has already been formed may be used as the valve metal substrate. In this case, an oxide film is also formed on the side of the cut element portion 212 by anodizing the valve metal substrate after cutting.

Next, a solid electrolyte layer is formed on the dielectric layer of the element portion 212. Specifically, the element portion 212 is immersed in a treatment liquid containing a solid electrolyte, so that the treatment liquid is impregnated into the porous portion of the valve metal substrate. After a predetermined period of immersion, the element portion 212 is removed from the treatment liquid and dried at a predetermined temperature for a predetermined period of time. The process of immersion in the treatment liquid, removal, and drying is repeated a predetermined number of times to form a solid electrolyte layer.

As the treatment liquid containing a solid electrolyte, for example, a dispersion liquid of a conductive polymer such as polypyrroles, polythiophenes, polyanilines, etc. is used. Among these, polythiophenes are preferred, and poly(3,4-ethylenedioxythiophene) called PEDOT is particularly preferred. The conductive polymer may also contain a dopant such as polystyrene sulfonic acid (PSS). A conductive polymer film can be formed by attaching a dispersion liquid of a conductive polymer to the outer surface of the dielectric layer and drying it. Alternatively, as the treatment liquid containing a solid electrolyte, a liquid containing a polymerizable monomer, for example, a polymerizable monomer such as 3,4-ethylenedioxythiophene, and an oxidizing agent may be used. This containing liquid can be attached to the outer surface of the dielectric layer to form a conductive polymer film by chemical polymerization. This conductive polymer film becomes the solid electrolyte layer.

Then, the element portion 212 is immersed in the carbon paste, pulled out, and dried to form a carbon layer in a predetermined area. The carbon paste is a conductive paste that contains carbon particles as a conductive component and a resin component such as epoxy resin or phenolic resin.

Then, the element portion 212 is immersed in the conductive paste, pulled up, and dried to form a cathode conductor layer in a predetermined area. Examples of conductive pastes for forming the cathode conductor layer include those that contain metal particles as a conductive component and a resin component such as epoxy resin or phenolic resin. Examples of metal particles include gold, silver, copper, platinum, etc. Among them, a silver paste that contains silver particles as a conductive component is preferable as a conductive paste for forming the cathode conductor layer.

As a result of the above, a workpiece 210 is created in which a capacitor element 10 is formed in each element portion 212.

Next, we will explain the chipping process.

First, as shown in FIG. 11, a first portion 221 having a plurality of through holes 223 is prepared. The first portion 221 has substantially rectangular parallelepiped through holes 223 with the same number and pitch as the capacitor elements 10 of the rectangular workpiece 210, and has a plurality of rows of such through holes 223.

Figure 17 is a diagram showing a schematic diagram of an example of a process for attaching an adhesive sheet to a first portion of an exterior body.

Next, as shown in FIG. 17, an adhesive sheet 250 (hereinafter, sometimes simply abbreviated as "sheet 250") is attached to the first portion 221 so as to close the first opening 223a of each through hole 223. That is, the adhesive sheet 250 is attached to the entire surface of one side of the first portion 221 so as to close one side of each through hole 223. This makes it possible to easily expose the end face of the collecting electrode 30 at the first end face 110e of the resin molded body 110 by peeling off the sheet 250 after sealing.

Note that it is sufficient for each through hole 223 to have the first opening 223a (lower opening) covered, and instead of attaching the adhesive sheet 250, the first opening 223a may be covered, for example, by placing the first part 221 on a flat table.

Figure 18 is a schematic diagram showing an example of a process for supplying conductive paste onto an adhesive sheet.

Next, as shown in FIG. 18, with the first opening 223a of each through hole 223 covered with the adhesive sheet 250, the conductive paste 230 is supplied onto the sheet 250 from the second opening 223b (upper opening) of each through hole 223. As a result, the conductive paste 230 is applied onto the sheet 250 in each through hole 223. For example, the conductive paste 230 may contain metal particles as a conductive component and a resin component such as epoxy resin or phenolic resin. For example, the metal particles may be silver, copper, nickel, tin, etc. Among them, the conductive paste 230 is preferably a silver paste containing silver particles as a conductive component. In addition, for example, a dispenser or the like may be used to supply the conductive paste 230.

Next, multiple capacitor elements 10 (superimposed body 11) are prepared and a resin curing process is carried out.

Figure 19A is a diagram showing an example of a process for preparing a stack of multiple capacitor elements. Figure 19B is a diagram showing an example of a process for inserting the stack into a through hole. Figure 19C is a diagram showing an example of a process for embedding a first portion of the tip side of each capacitor element in a conductive paste. Figure 19D is a diagram showing an example of a process for filling a liquid material into a gap between each capacitor element (stack) inserted into a through hole and a first portion of the exterior body.

First, as shown in FIG. 19A, multiple workpieces 210 are prepared, on which multiple capacitor elements 10 are formed in a strip shape, and a predetermined number of workpieces 210 are bundled together and fixed with a jig such as a clamp (not shown) so that the multiple capacitor elements 10 are arranged along a first direction. This results in a stack 11 of multiple capacitor elements 10 being arranged in a row (a row aligned perpendicular to the paper surface of FIG. 19A).

Then, multiple capacitor elements 10 are inserted into each through hole 223. That is, as shown in FIG. 19B, the multiple fixed workpieces 210 are moved relative to the first portion 221, and the stacks 11 (cathode and anode) are inserted into the through holes 223 in the same row from the second openings 223b.

In this way, by using the workpiece 210 in which multiple capacitor elements 10 are connected in the form of strips at regular intervals to the holding portion 211, the capacitor elements 10 (cathode and anode) can be inserted in strip units into the first portion 221, which can significantly improve productivity compared to inserting the capacitor elements 10 one by one or the stacks 11 one by one into the first portion 221.

At this time, as shown in FIG. 19C, the conductive paste 230 is spread by the tip of each capacitor element 10, i.e., the first portion 43a of the cathode 43, and at least the first portion 43a on the tip side of the cathode 43 of each capacitor element 10 is embedded in the conductive paste 230. In other words, the conductive paste 230 is connected to all of the capacitor elements 10.

Then, with each cathode 43 embedded, the conductive paste 230 is cured on the sheet 250, for example, by heating. As a result, the collector electrode 30 (see FIG. 2) is formed with at least the first portion 43a on the tip side of the cathode 43 of each capacitor element 10 embedded in the collector electrode 30.

Next, as shown in FIG. 19D, the liquid material 222 is filled into the gap between each capacitor element 10 (cathode and anode) inserted into each through hole 223, i.e., between the stack 11 and the first part 221. For example, the liquid material 222 is injected into each through hole 223 using a dispenser or the like, and vacuum degassing is performed to fill the gap between the first part 221 and each capacitor element 10 (cathode and anode), i.e., between the stack 11. The viscosity of the liquid material 222 may be reduced by heating during injection or vacuum degassing. The liquid material 222 contains the above-mentioned second resin material (however, liquid before hardening). The resin contained in the liquid second resin material is preferably a thermosetting resin such as epoxy resin, silicone resin, or urethane resin.

The liquid material 222 before curing preferably has a viscosity of 100 Pa·s or less at 25°C. A viscosity of 100 Pa·s or less allows for easy filling by simply degassing and heating in a vacuum oven, thereby increasing productivity. The viscosity of the liquid material 222 before curing is more preferably 30 Pa·s or less at 25°C, and even more preferably 5 Pa·s or less.

Although there is no lower limit to the viscosity of the liquid material 222 before hardening, it is preferable that the viscosity is not too low so that the liquid material 222 does not leak from the gap between the first portion 221 and the sheet 250 after the liquid material 222 is filled and before it is heated and hardened. More specifically, the viscosity of the liquid material 222 before hardening is usually 0.01 Pa·s or more at 25°C, preferably 0.1 Pa·s or more, and more preferably 0.3 Pa·s or more.

Then, the liquid material 222 filled in the gaps between each capacitor element 10 (superimposed body 11) and the first portion 221 is cured. For example, the liquid material 222 is heated and cured in a vacuum oven to form the second portion 222a of the exterior body 220 (the portion that becomes the second portion 22 of the exterior body 20).
A small number of air bubbles may remain in the second portion 222a which is the hardened product of the liquid material 222. A small gap may remain between the second portion 222a and the first portion 221 and/or between the second portion 222a and at least one capacitor element 10.

Then, for the other rows of through holes 223, the conductive paste 230 is supplied, multiple capacitor elements 10 (superimposed body 11) are inserted, the liquid material 222 is filled, and the liquid material 222 is hardened, so that multiple capacitor elements 10 (superimposed body 11) and second portions 222a are housed in all of the through holes 223.

After the resin curing process, the sheet 250 is peeled off from the first portion 221. The collector electrodes 30 to which the capacitor elements 10 are connected are exposed on the peeled surface, and this peeled surface becomes the first end surface 110e of the resin molded body 110. At least one end surface of the cathode may be exposed on this peeled surface.

On the other hand, the upper part of the first portion 221 contains unnecessary parts of each capacitor element 10, unnecessary parts of the liquid material 222, and the holding portion 211 of the workpiece 210. In addition, the height of the first portion 221 is the length of the chip in the longitudinal direction, and therefore needs to be adjusted to a predetermined length. Therefore, the unnecessary parts on the upper part of the first portion 221 are removed with a grinder or the like. The surface exposed after the unnecessary parts have been removed becomes the second end surface 110f of the resin molded body 110. The anode 40 (foil made of a valve metal base) of each capacitor element 10 is exposed on the second end surface 110f.

Next, cutting is done to separate the pieces.

Figure 20 is a schematic diagram showing an example of a process for cutting the first portion of the exterior body around the through hole.

As shown in FIG. 20, the first portion 221 is cut around each through hole 223. This makes it easy to form the first portion 21 of the tubular structure from the first portion 221. For example, a predetermined cut line (dotted line in FIG. 20) on the outside of each through hole 223 is cut using a dicer or the like.

This results in a resin molded body 110 having a stack 11 of capacitor elements 10.

The resin molded body 110 may then be barrel polished. Specifically, the resin molded body 110 may be polished by sealing the resin molded body 110 together with an abrasive in a barrel tank and rotating the barrel tank. This allows the corners and ridges of the resin molded body 110 to be rounded.

If necessary, metal particles may be sprayed and collided by an aerosol deposition method onto the second end surface 110f (anode end surface) of the resin molded body 110 that has been barrel polished. This may form a metal film on the base end surface 40b of each of the anodes 40 exposed on the second end surface 110f (anode end surface) of the resin molded body 110.

Next, the first external electrode 120 and the second external electrode 130 are formed on the first end face 110e (cathode end face) and the second end face 110f (anode end face) of the resin molded body 110, respectively. For example, a conductive paste is applied by a screen printing method or the like and cured to form resin electrode layers as the first external electrode 120 and the second external electrode 130, respectively. As the conductive paste for forming the resin electrode layer, a silver paste containing silver particles as a conductive component is suitable. After that, a plating layer may be formed on the resin electrode layer by plating.

At this time, the first external electrode 120 may be formed as a thin sputtered film and/or vapor deposition film, for example, several μm thick, by sputtering or vapor deposition.

The above method can be used to obtain an electrolytic capacitor 100.

In the above embodiment, the case where the collector electrode 30 is provided has been described, but the cathode 43 of each capacitor element 10 may be directly connected to the first external electrode 120 without providing the collector electrode 30. In this case, for example, after peeling off the adhesive sheet 250, the lower part of the first part 221 to which the sheet 250 was attached may be scraped off with a grinder or the like to expose each cathode 43 on the first end surface 110e (cathode end surface) of the resin molded body 110, and the first external electrode 120 may be formed on each cathode 43 exposed on the first end surface 110e.

In addition, when the collecting electrode 30 is not provided, the resin curing process may be performed according to the following process. That is, first, the liquid material 222 is injected into each through hole 223 of the first part 221 by using a dispenser or the like to fill it. Next, a plurality of capacitor elements 10 (superimposed body 11) are inserted into each through hole 223 filled with the liquid material 222, and the liquid material 222 is filled into the gap between the inserted plurality of capacitor elements 10 (superimposed body 11) and the first part 221. For example, after the insertion of the plurality of capacitor elements 10, vacuum degassing is performed to fill the liquid material 222 into the gap between the plurality of capacitor elements 10 and the first part 221. Then, the liquid material 222 filled into the gap between each capacitor element 10 (superimposed body 11) and the first part 221 is cured by heating it in a vacuum oven, for example.

In the above embodiment, the exterior body 20 is composed of only two types of resin materials, i.e., the first part 21 and the second part 22. However, the exterior body of the electrolytic capacitor may be composed of three types of resin materials. For example, one or more intermediate resin layers made of resin materials may be provided between the first part and the second part. Such an intermediate resin layer may be formed, for example, by forming the second part that seals the stack of multiple capacitor elements with dimensions smaller than the through hole of the first part by transfer molding or the like, and then inserting the stack of capacitor elements together with the second part into the through hole of the first part, and then filling the gap between the second part and the first part with liquid resin material and curing it.

In addition, in the above embodiment, a case has been described in which multiple resin molded bodies 110 are simultaneously produced using a first portion 221 having multiple through holes 223, but in the manufacturing method of the electrolytic capacitor of the present invention, the resin molded bodies may be produced one by one using a first portion having only one through hole.

The exterior body may be composed of only one type of part, or a laminate of multiple capacitor elements may be encapsulated by transfer molding or compression molding to obtain a resin molded body. The electrolytic capacitor of the present invention can be obtained by using a resin composition containing a resin component and insulating fibers as the resin composition for obtaining the resin molded body, and adjusting the orientation of the insulating fibers.

In the above embodiment, the electrolytic capacitor 100 is described as a solid electrolytic capacitor, but the electrolytic capacitor of the present invention is not particularly limited as long as it is an electrolytic capacitor that includes a capacitor element and an exterior body, and may be, in addition to a solid electrolytic capacitor, for example, a film capacitor, an electric double layer capacitor, a solid-state battery, etc.

The following items are disclosed in this specification:

The present disclosure (1) provides a rectangular parallelepiped resin molded body including a stack in which a plurality of capacitor elements, each of which includes an anode having a dielectric layer on a surface thereof and a cathode facing the anode, are arranged along a first direction, and an exterior body that seals a periphery of the stack,
the resin molded body has a first main surface and a second main surface opposing each other in the first direction, a first end surface from which the cathode is exposed and a second end surface from which the anode is exposed, which face each other in a second direction perpendicular to the first direction, and a first side surface and a second side surface opposing each other in a third direction perpendicular to the first direction and the second direction,
The electrolytic capacitor includes an outer casing including insulating fibers, the insulating fibers being oriented in the third direction and/or the first direction.

Disclosure (2) is the electrolytic capacitor according to disclosure (1), in which, when the exterior body is viewed from the first direction, the insulator fibers are oriented in the third direction, and an acute angle between the orientation direction of the insulator fibers and the third direction is 40° or less for at least 60% of the insulator fibers.

The present disclosure (3) is an electrolytic capacitor according to the present disclosure (2), in which, when the exterior body is viewed from the first direction, the insulator fibers are oriented in the third direction, and an acute angle between the orientation direction of the insulator fibers and the third direction is 20° or less for at least 60% of the insulator fibers.

The present disclosure (4) is an electrolytic capacitor in any combination with any of the present disclosures (1) to (3), in which, when the exterior body is viewed from the second direction, the insulator fibers are oriented in the third direction, and an acute angle between the orientation direction of the insulator fibers and the third direction is 40° or less for at least 60% of the insulator fibers.

The present disclosure (5) is the electrolytic capacitor according to the present disclosure (4), in which, when the exterior body is viewed from the second direction, the insulator fibers are oriented in the third direction, and an acute angle between the orientation direction of the insulator fibers and the third direction is 20° or less for at least 60% of the insulator fibers.

The present disclosure (6) is an electrolytic capacitor in any combination with any of the present disclosures (1) to (5), in which, when the exterior body is viewed from the third direction, the insulator fibers are oriented in the first direction, and an acute angle between the orientation direction of the insulator fibers and the first direction is 40° or less for at least 60% of the insulator fibers.

The present disclosure (7) is the electrolytic capacitor according to the present disclosure (6), in which, when the exterior body is viewed from the third direction, the insulator fibers are oriented in the first direction, and an acute angle between the orientation direction of the insulator fibers and the first direction is 20° or less for at least 60% of the insulator fibers.

The present disclosure (8) is an electrolytic capacitor in any combination with any of the present disclosures (1) to (7), in which, when the exterior body is viewed from the second direction, the insulator fibers are oriented in the first direction, and an acute angle between the orientation direction of the insulator fibers and the first direction is 40° or less for at least 60% of the insulator fibers.

The present disclosure (9) is the electrolytic capacitor according to the present disclosure (8), in which, when the exterior body is viewed from the second direction, the insulator fibers are oriented in the first direction, and an acute angle between the orientation direction of the insulator fibers and the first direction is 20° or less for at least 60% of the insulator fibers.

The present disclosure (10) is an electrolytic capacitor in any combination with any of the present disclosures (1) to (9), in which the average fiber length of the insulating fibers is 100 μm or more.

The present disclosure (11) is an electrolytic capacitor in any combination with any of the present disclosures (1) to (10) in which the insulating fibers are amorphous fibers.

The present disclosure (12) is an electrolytic capacitor in any combination with any of the present disclosures (1) to (11), in which the insulating fibers contain 50% by weight or more of aluminum oxide or silicon oxide.

The present disclosure (13) provides a method for manufacturing a capacitor comprising: preparing a stack in which a plurality of capacitor elements, each of which includes an anode having a dielectric layer on a surface thereof and a cathode facing the anode, are arranged along a first direction; and sealing the stack with an exterior body,
In the electrolytic capacitor to be manufactured, when a direction perpendicular to the first direction and in which the anode and the cathode face each other is defined as a second direction, and a direction perpendicular to the first direction and the second direction is defined as a third direction,
In the sealing step, a resin composition containing a resin and insulating fibers is caused to flow along a direction that will be the third direction or the first direction of the electrolytic capacitor to be manufactured.

The present disclosure (14) is a method for producing an electrolytic capacitor according to the present disclosure (13), in which the resin is a thermoplastic resin and the sealing step includes an injection molding step.

The present disclosure (15) is a method for manufacturing an electrolytic capacitor according to the present disclosure (14), in which the insulator fibers are oriented along the gate direction in the injection molding process.

10 Capacitor element 11 Stack 20 Exterior body 21 First portion 21c End surface of first portion 22 Second portion 23 Through hole 30 Collector electrode 40 Anode 40a Anode tip surface 40b Anode base end surface 40c Anode first portion 40d Anode second portion 41 Dielectric layer 42 Mask layer 43 Cathode 43a Cathode first portion 43b Cathode second portion 44 Solid electrolyte layer 45 Carbon layer 46 Cathode conductor layer 50a Crack 50c occurring on first main surface of resin molded body Crack 60 occurring on first side surface of resin molded body Insulator fiber 100 Electrolytic capacitor 110 Resin molded body 110a First main surface 110b Second main surface 110c First side surface 110d Second side surface 110e First end surface 110f Second end surface 120 First external electrode 130 Second external electrode 210 Work 211 Holding portion 212 Element portion 220 Exterior body 221 First portion of exterior body 222 Liquid material 222a Second portion of exterior body 223 Through hole 223a First opening of through hole 223b Second opening of through hole 230 Conductive paste 250 Adhesive sheets 261, 271 Runners 262, 272 Gate

Claims (15)

a rectangular parallelepiped resin molded body including a stack in which a plurality of capacitor elements, each of which includes an anode having a dielectric layer on a surface thereof and a cathode facing the anode, are arranged along a first direction, and an exterior body that seals the periphery of the stack;
the resin molded body has a first main surface and a second main surface opposing each other in the first direction, a first end surface from which the cathode is exposed and a second end surface from which the anode is exposed, which face each other in a second direction perpendicular to the first direction, and a first side surface and a second side surface opposing each other in a third direction perpendicular to the first direction and the second direction,
An electrolytic capacitor, wherein the outer casing contains insulating fibers, and the insulating fibers are oriented in the third direction in the portions constituting the first main surface and the second main surface , and/or are oriented in the first direction in the portions constituting the first side surface and the second side surface . The electrolytic capacitor according to claim 1, wherein, when the outer casing is viewed from the first direction, the insulator fibers are oriented in the third direction, and an acute angle between the orientation direction of the insulator fibers and the third direction is 40° or less for at least 60% of the insulator fibers. The electrolytic capacitor according to claim 2, wherein when the outer casing is viewed from the first direction, the insulator fibers are oriented in the third direction, and an acute angle between the orientation direction of the insulator fibers and the third direction is 20° or less for at least 60% of the insulator fibers. An electrolytic capacitor according to any one of claims 1 to 3, in which, when the exterior body is viewed from the second direction, the insulator fibers are oriented in the third direction, and an acute angle between the orientation direction of the insulator fibers and the third direction is 40° or less for at least 60% of the insulator fibers. The electrolytic capacitor according to claim 4, wherein, when the outer casing is viewed from the second direction, the insulator fibers are oriented in the third direction, and an acute angle between the orientation direction of the insulator fibers and the third direction is 20° or less for at least 60% of the insulator fibers. An electrolytic capacitor according to any one of claims 1 to 3, in which, when the exterior body is viewed from the third direction, the insulator fibers are oriented in the first direction, and an acute angle between the orientation direction of the insulator fibers and the first direction is 40° or less for at least 60% of the insulator fibers. The electrolytic capacitor according to claim 6, wherein, when the outer casing is viewed from the third direction, the insulator fibers are oriented in the first direction, and an acute angle between the orientation direction of the insulator fibers and the first direction is 20° or less for at least 60% of the insulator fibers. An electrolytic capacitor according to any one of claims 1 to 3, in which, when the exterior body is viewed from the second direction, the insulator fibers are oriented in the first direction, and an acute angle between the orientation direction of the insulator fibers and the first direction is 40° or less for at least 60% of the insulator fibers. The electrolytic capacitor according to claim 8, wherein, when the outer casing is viewed from the second direction, the insulator fibers are oriented in the first direction, and an acute angle between the orientation direction of the insulator fibers and the first direction is 20° or less for at least 60% of the insulator fibers. An electrolytic capacitor according to any one of claims 1 to 3, in which the average fiber length of the insulating fibers is 100 μm or more. An electrolytic capacitor according to any one of claims 1 to 3, in which the insulating fibers are amorphous fibers. An electrolytic capacitor according to any one of claims 1 to 3, in which the insulating fibers contain 50% by weight or more of aluminum oxide or silicon oxide. The method includes the steps of: preparing a stack in which a plurality of capacitor elements, each of which includes an anode having a dielectric layer on a surface thereof and a cathode facing the anode, are arranged along a first direction; and sealing the stack with an exterior body,
In the electrolytic capacitor to be manufactured, when a direction perpendicular to the first direction and in which the anode and the cathode face each other is defined as a second direction, and a direction perpendicular to the first direction and the second direction is defined as a third direction,
A method for manufacturing an electrolytic capacitor, in which the sealing process involves flowing a resin composition containing resin and insulator fibers along a direction that will be the third direction of the electrolytic capacitor to be manufactured to form portions that constitute the first and second main surfaces of the outer casing that face each other in the first direction, or flowing the resin composition along a direction that will be the first direction of the electrolytic capacitor to be manufactured to form portions that constitute the first and second side surfaces of the outer casing that face each other in the third direction . The method for manufacturing an electrolytic capacitor according to claim 13, wherein the resin is a thermoplastic resin, and the sealing step includes an injection molding step. The method for manufacturing an electrolytic capacitor according to claim 14, wherein the insulator fibers are oriented along the gate direction in the injection molding process.

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