JP7165903B2 - Electrolytic capacitor and manufacturing method thereof - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrolytic capacitor using a sealing member having an elastic member, and a manufacturing method thereof.

An electrolytic capacitor includes a capacitor element, a case that accommodates the capacitor element, and a sealing member that seals an opening of the case. The sealing member has an elastic member that is fitted into the opening of the case, and the elastic member is made of an elastic material such as rubber or rubber-like polymer (Patent Document 1, etc.).

JP-A-11-274011

When an electrolytic capacitor is used in a high-temperature environment, deterioration of the elastic member becomes remarkable. With conventional elastic members, it is difficult to sufficiently suppress deterioration.

One aspect of the present invention includes a capacitor element, a case having an opening and housing the capacitor element, and a sealing member that seals the opening,
The sealing member includes an elastic member fitted in the opening, and an insulating inorganic layer formed on the surface of the elastic member,
The elastic member has a first main surface arranged on the opening side,
The inorganic layer relates to an electrolytic capacitor formed on at least part of the first main surface.

Another aspect of the present invention is a method for manufacturing an electrolytic capacitor comprising a capacitor element, a case having an opening for accommodating the capacitor element, and a sealing member for sealing the opening,
The sealing member comprises an elastic member having a first main surface arranged on the opening side,
The manufacturing method relates to an electrolytic capacitor manufacturing method including an inorganic layer forming step of forming an insulating inorganic layer on at least part of the first main surface.

Deterioration of the elastic member constituting the sealing member can be suppressed in the electrolytic capacitor.

1 is a schematic cross-sectional view of an electrolytic capacitor according to a first embodiment of the invention; FIG. 2 is a schematic diagram for explaining the configuration of a capacitor element of the electrolytic capacitor of FIG. 1; FIG. FIG. 6 is a schematic cross-sectional view of a sealing member and its surroundings in an electrolytic capacitor according to a second embodiment of the present invention; FIG. 8 is a schematic cross-sectional view of a sealing member and its periphery in an electrolytic capacitor according to a third embodiment of the present invention; FIG. 10 is a schematic cross-sectional view of a sealing member and its periphery in an electrolytic capacitor according to a fourth embodiment of the present invention; FIG. 5 is a schematic cross-sectional view of an electrolytic capacitor according to a fifth embodiment of the invention;

[Electrolytic capacitor]
An electrolytic capacitor according to one embodiment of the present invention includes a capacitor element, a case having an opening and accommodating the capacitor element, and a sealing member that seals the opening. The sealing member includes an elastic member fitted in the opening of the case, and an insulating inorganic layer formed on the surface of the elastic member. The elastic member has a first main surface arranged on the opening side of the case, and the inorganic layer is formed on at least part of the first main surface.

Electrolytic capacitors are sometimes assumed to be used in high-temperature environments, such as in the engine compartment of automobiles. The opening of the case that houses the capacitor element is sealed by inserting an elastic member. Oxidative deterioration. Specifically, in a high-temperature environment, radicals are generated from the elastic polymer by the action of heat, oxygen is added, and this adduct further converts the elastic polymer into radicals. As these processes are repeated, the polymer chain of the elastic polymer becomes shorter and the elastic polymer deteriorates. Since the shortened elastic polymer evaporates due to the action of heat, the elastic member becomes brittle and the sealing function deteriorates.

In addition, carbon such as carbon black is generally added to the elastic member from the viewpoint of ensuring strength. Many such carbons exhibit electrical conductivity. However, when the elastic polymer constituting the elastic member is oxidized and degraded as described above, the carbon (particles and fibers) contained in the elastic member are likely to come into contact with each other, and the insulating property of the elastic member is lowered. In particular, since the first main surface of the elastic member on the side of the opening of the case is exposed to the outside air, deterioration of the elastic polymer and deterioration of insulating properties are likely to be remarkable on and near the first main surface. . In an electrolytic capacitor, an anode lead and a cathode lead, which are electrically connected to a capacitor element, are normally pulled out through separate through holes formed in an elastic member. Therefore, when the insulating property of the elastic member is lowered, leakage current is likely to occur between the anode lead and the cathode lead. More specifically, for example, when the first principal surface of the elastic member and its vicinity deteriorates and the insulation deteriorates, a leakage current flows between the anode lead and the cathode lead on the first principal surface and its vicinity. easier.

In this embodiment, as described above, the inorganic layer is formed on at least a portion of the first main surface of the elastic member that is located on the side of the opening of the case. Since the inorganic layer has high gas barrier properties, the inorganic layer can reduce or suppress contact of the elastic member with oxygen, and as a result, can suppress deterioration of the elastic member. Since deterioration of the elastic member is suppressed, high sealing performance by the sealing member can be ensured. In addition, the inorganic layer suppresses deterioration of the elastic member, thereby suppressing deterioration of the insulating property of the elastic member due to contact between carbon atoms contained in the elastic member. Therefore, it is possible to suppress the occurrence of leakage current between the anode lead and the cathode lead in the elastic member (in particular, the first main surface and its vicinity). In this way, by suppressing deterioration of the elastic member, it is possible to ensure high sealing performance of the elastic member and suppress leakage current between leads (that is, because the electrolytic capacitor has high heat resistance). ), it is possible to prolong the life of electrolytic capacitors.

The thermal conductivity of the inorganic material forming the inorganic layer is preferably higher than the thermal conductivity of the elastic polymer forming the elastic member. In this case, since the inorganic layer has a higher heat dissipation property than the elastic member, heat can easily escape from the inorganic layer to the case or the like, so that deterioration of the elastic member can be further suppressed. In addition, it is preferable that the inorganic layer is in contact with the case.

The inorganic layer preferably contains at least one inorganic material selected from the group consisting of oxides and nitrides. The inorganic material preferably contains at least one selected from the group consisting of Al, Si, and Ti. In addition to having high heat resistance, such an inorganic material easily forms a dense inorganic layer, so that high gas barrier properties can be easily obtained. In addition, since these inorganic materials have high thermal conductivity and high heat dissipation, the effect of suppressing deterioration of the elastic member is further enhanced.

From the viewpoint of easily ensuring high coverage with the inorganic layer and easily obtaining high film properties, it is preferable to form the inorganic layer by a vapor phase method. It is preferable to form an inorganic layer. According to the vapor phase method, the inorganic layer can be formed all at once, and a more uniform inorganic layer can be formed even if the thickness is small. In addition, according to the ALD method, the inorganic layer can be formed even on the surface of the elastic member at very slight irregularities and gaps. For example, when the electrolytic capacitor has leads drawn out from the capacitor element as described above, and the elastic member has through-holes through which the leads pass, the inorganic layer further forms the wall surfaces of the through-holes. It is preferable that it is also formed at least partially. As described above, when a vapor phase method such as the ALD method is used, high coverage of the inorganic layer can be ensured, so that the inorganic layer can be formed on the walls of the through holes. When the inorganic layer is formed on the wall surface of the through-hole, the effect of suppressing deterioration of the elastic member can be further enhanced, and the occurrence of leakage current between leads can be further suppressed.

The inorganic layer is preferably formed on 80% or more of the wall surfaces of the through holes. By covering many areas of the wall surface of the through hole with the inorganic layer, the effect of suppressing deterioration of the elastic member and occurrence of leakage current between the leads is further enhanced.

The elastic member has a first main surface, a second main surface arranged inside the case and opposite to the first main surface, a side surface facing the inner wall surface (that is, the inner side wall surface) of the case, and and an inorganic layer is preferably formed on at least part of this side surface. Since the inorganic layer is also present between the case and the elastic member, the effect of suppressing deterioration of the elastic member can be further enhanced.

The thickness of the inorganic layer is preferably 10 nm or more and 1 μm or less. When the inorganic layer has such a thickness, it is possible to ensure high gas barrier properties and to suppress the influence on product dimensions.

FIG. 1 is a schematic cross-sectional view of an electrolytic capacitor according to one embodiment of the present invention, and FIG. 2 is a schematic view showing a part of a capacitor element of the same electrolytic capacitor.

The electrolytic capacitor includes, for example, a capacitor element 10, a cylindrical case 11 that accommodates the capacitor element 10, a sealing member 17 that includes an elastic member 12 that closes the opening of the case 11, and a seat plate 13 that faces the elastic member 12. and two leads extending from the through hole 18 of the elastic member 12 and penetrating the seat plate 13 . In the illustrated example, one lead includes lead wire 14A and lead tab 15A, and the other lead includes lead wire 14B and lead tab 15B. Lead tabs 15A and 15B are connected to electrodes of capacitor element 10, respectively. Lead wires 14A and 14B respectively connected to the lead tabs 15A and 15B are drawn out from the two through holes 18, respectively. The vicinity of the open end of the case 11 is drawn inward, and the open end is curled and crimped against the elastic member 12 . A region 11a is formed in a portion of the case 11 facing the side surface 12c of the elastic member 12, where the diameter of the case 11 is reduced by drawing (specifically, horizontal drawing).

The elastic member 12 has a first main surface 12a arranged on the opening side of the case 11, a second main surface 12b opposite to the first main surface 12a, and a side surface 12c facing the inner wall surface of the case 11. It has The second main surface 12b is arranged inside the case 11 . In the through hole 18 portion, the elastic member 12 has a wall surface 12d. That is, the through hole 18 is surrounded by the wall surface 12d of the elastic member 12. As shown in FIG. In the illustrated example, the sealing member 17 includes an elastic member 12 and an inorganic layer 16 formed to cover the first main surface 12a of the elastic member 12 . Since the inorganic layer 16 prevents the elastic member 12 from coming into contact with oxygen, deterioration of the elastic member 12 can be suppressed even when the electrolytic capacitor is exposed to a high-temperature environment.

Note that the capacitor element 10 is produced from a wound body as shown in FIG. The wound body includes an anode section 21 connected to the lead tab 15A, a cathode section 22 connected to the lead tab 15B, and a separator 23. As shown in FIG. The wound body shown in FIG. 2 is a semi-finished product without electrolyte.

Anode part 21 and cathode part 22 are wound with separator 23 interposed therebetween. The outermost circumference of the wound body is fixed by a winding stop tape 24 . In addition, FIG. 2 shows a partially unfolded state before stopping the outermost circumference of the wound body.

Anode portion 21 includes a metal foil having a roughened surface, and a chemical conversion film is formed on the metal foil having the unevenness. In capacitor element 10, a solid electrolyte adheres to at least part of the surface of the chemical conversion film. The solid electrolyte may cover at least part of the surface of the cathode portion 22 and/or the surface of the separator 23 . An electrolytic capacitor is manufactured by housing a capacitor element 10 having a solid electrolyte formed therein in a case 11 and sealing the opening of the case 11 with a sealing member. When an electrolytic solution is used, the electrolytic solution is accommodated in case 11 together with capacitor element 10 .

Although FIG. 1 shows the case where the inorganic layer 16 is formed only on the first main surface 12a, the position of the inorganic layer 16 is not limited to this case. The inorganic layer 16 may be formed on at least the first main surface 12a of the elastic member 12, and the inorganic layer 16 may be formed from the group consisting of the first main surface 12a, the second main surface 12b, the side surface 12c, and the wall surface 12d of the through hole. and at least one selected. A few examples of these cases are shown in FIGS. 3 to 5 are schematic cross-sectional views showing a sealing member and its surroundings in electrolytic capacitors according to other embodiments, respectively. In these examples, the only difference is the position of the inorganic layer 16, and the other configurations are the same as in FIG. 1, and the description of FIG. 1 can be referred to.

In FIG. 3, the inorganic layer 16 is formed on the first main surface 12a and the second main surface 12b. In FIG. 4, the inorganic layer 16 is formed on the first main surface 12a, the second main surface 12b, and the wall surface 12d of the through hole 18. In FIG. In FIG. 5, the inorganic layer 16 is formed on the first main surface 12a, the second main surface 12b, the wall surface 12d of the through hole 18, and the side surface 12c. Although not shown, the inorganic layer 16 may be formed, for example, on the first main surface 12a and the side surface 12c of the through hole 18, and the first main surface 12a, the second main surface 12b, and the side surface 12c may be formed. It may be formed with

In this way, when the inorganic layer 16 is formed on the first main surface 12a and other surfaces of the elastic member 12, the effect of suppressing deterioration of the elastic member 12 can be further enhanced. The inorganic layer 16 can be easily formed on the walls of the through holes 18 by using a vapor phase method such as ALD. Therefore, since high coverage of the inorganic layer 16 can be ensured, deterioration of the elastic member 12 can be further suppressed, and deterioration of the insulating property of the elastic member 12 can be suppressed. Further, when the inorganic layer 16 is formed on the side surface 12c of the elastic member 12, the inorganic layer 16 is formed between the case 11 and the elastic member 12, so that the effect of suppressing deterioration of the elastic member 12 is further enhanced. be able to.

The inorganic layer 16 may be formed on at least a portion of the first main surface 12a of the elastic member 12, and may be formed on the entire first main surface 12a. Further, when the inorganic layer 16 is formed on a surface other than the first main surface 12a of the elastic member 12, the inorganic layer 16 may be formed on at least a part of each surface, and may be formed on the entire surface. good too.

In FIGS. 1 and 3 to 5, on the first main surface 12a of the elastic member 12, the inorganic layer 16 is also formed below the open end of the curled case 11 and its vicinity (that is, , the case where the open end of the case 11 and its vicinity exist above the inorganic layer 16). 1 and 3 to 5 show the case where the opening of the case 11 is sealed using the sealing member 17 having the elastic member 12 with the inorganic layer 16 formed thereon. However, it is not limited to such a case, and the inorganic layer 16 may be formed after the opening of the case 11 is sealed with the elastic member 12 . This case is shown in FIG.

FIG. 6 is a schematic cross-sectional view of an electrolytic capacitor according to still another embodiment. 6 differs from FIG. 1 in the position of the inorganic layer 16 and the formation of the inorganic layer 19 on the surfaces of the lead wires 14A and 14B and the surface of the case 11, but the other configurations are the same as in FIG. It is the same as FIG. 2, and the description of FIGS. 1 and 2 can be referred to.

In FIG. 6, the inorganic layer is formed over the entire surface of the electrolytic capacitor. In FIG. 6, for convenience, the inorganic layer formed on the elastic member 12 is assumed to be the inorganic layer 16, and the other regions (specifically, the outer surface of the case 11 and the lead wires 14A and 14B exposed from the elastic member 12). The inorganic layer formed on the surface of the portion) is referred to as the inorganic layer 19 . In the electrolytic capacitor having such inorganic layers 16 and 19, the capacitor element 10 is accommodated in the case 11, and the opening of the case 11 is sealed with the elastic member 12 in accordance with the case of FIG. It can be obtained by assembling an electrolytic capacitor (precursor) without layers 16 and 19 and then forming inorganic layers 16 and 19 on the surface of this precursor.

Although FIG. 6 shows the case where the inorganic layer is formed on the entire surface of the electrolytic capacitor, the elastic member is not limited to this case, and the elastic member can be formed as long as the inorganic layer can be formed at least on the surface of the opening side of the electrolytic capacitor. 2 can be obtained. In these cases, air is prevented from entering between the elastic member 12 and the lead or from the portion where the case 11 is crimped against the elastic member 12, so deterioration of the elastic member 12 can be further suppressed. . In addition, it is easy to ensure insulation between the two leads.

FIG. 6 shows an example in which an inorganic layer is formed on the surface of the precursor after assembling the electrolytic capacitor (precursor) without the inorganic layers 16 and 19, but the present invention is not limited to this case. Alternatively, the inorganic layer may be formed on the surface of the electrolytic capacitor after forming the inorganic layer on (at least part of) at least the first main surface 12a of the elastic member 12 .

The configuration of the electrolytic capacitor will be described in more detail below.
(Sealing member 17)
The sealing member 17 has an elastic member 12 and an inorganic layer 16 . Sealing member 17 seals the opening of case 11 in a state in which elastic member 12 is fitted into the opening of case 11 that accommodates capacitor element 10 .

The elastic member 12 has a first main surface arranged on the opening side of the case 11 . The inorganic layer 16 is formed at least on the first main surface 12a. The inorganic layer 16 may be formed on at least a portion of the first main surface 12a, and the inorganic layer 16 may be formed on the entire first main surface 12a or may be formed on a portion of the first main surface 12a. . From the viewpoint of reducing or suppressing the contact of the elastic member 12 with oxygen, in the electrolytic capacitor, it is preferable that at least the inorganic layer 16 is formed on the portion where the elastic member 12 is exposed from the case 11. The inorganic layer 16 is formed on 80% or more (preferably 90% or more) of the main surface 12a (that is, the area of the first main surface 12a (specifically, the projected area in the thickness direction of the elastic member 12)). is preferred.

The elastic member 12 generally has a second major surface 12b located opposite the first major surface 12a. Also, the elastic member 12 has a side surface 12c facing the inner wall surface of the case 11 . The inorganic layer 16 may be formed on the second main surface 12b and/or the side surface 12c in addition to the first main surface 12a. The inorganic layer 16 may be formed at least partially on each of the second main surface 12b and the side surface 12c. When the inorganic layer 16 is formed on at least part of the side surface 12c, the inorganic layer 16 exists between the case 11 and the elastic member 12, and air passes between the case 11 and the side surface 12c of the elastic member 12. Therefore, deterioration of the elastic member 12 can be further suppressed.

When the elastic member 12 has a through hole 18 through which the lead drawn out from the capacitor element 10 passes, the wall surface of the through hole 18 of the elastic member 12 (specifically, the wall surface of the elastic member 12 surrounding the through hole 18) An inorganic layer 16 may be formed. Since the through-holes 18 are small holes, the inorganic layer 16 on the walls of the through-holes 18 is usually formed by a vapor phase method such as ALD. Therefore, such an inorganic layer 16 has a high covering property and is advantageous in further suppressing deterioration of the elastic member 12 . In addition, since the inorganic layer is also present in the gap between the lead and the elastic member 12, the effect of suppressing deterioration of the elastic member 12 can be further enhanced.

The inorganic layer 16 may be formed on at least a portion of the wall surface of the through hole 18 of the elastic member 12, and may be formed on the entire wall surface. From the viewpoint of further reducing or suppressing the contact of the elastic member 12 with oxygen, it is preferable that the inorganic layer 16 be formed on the wall surface of the through-hole 18 over 80% or more of the wall surface (that is, the wall surface area). , 90% or more.

Note that the fact that the inorganic layer is formed on 80% or more (or 90% or more) of the area of the main surface or wall surface means, for example, that each main surface or wall surface is formed of a plurality of regions having the same area (for example, 20 area), and the ratio of the area where the inorganic layer component is detected to the entire area is 80% or more (or 90% or more). The detection of the components of the inorganic layer can be performed, for example, by detecting the presence of metal elements contained in the inorganic layer by inductively coupled plasma (ICP) emission spectrometry.

Elastic member 12 includes an elastic polymer. An insulating material is used as the elastic polymer. Examples of elastic polymers include butyl rubber, isoprene rubber, silicone rubber, fluororubber, ethylene propylene rubber, chlorosulfonated polyethylene rubber (hypalon rubber, etc.), and the like. One type of elastic polymer may be used alone, or two or more types may be used in combination. Although such an elastic polymer has a high sealing property, it is likely to be deteriorated by the action of oxygen as described above, resulting in deterioration of the elastic member 12 . According to this embodiment, since the inorganic layer 16 is provided, deterioration of the elastic member 12 can be effectively suppressed even when the elastic member 12 contains such an elastic polymer.

The elastic member 12 may optionally contain additives (reinforcing agents, antioxidants, cross-linking agents, cross-linking accelerators, dispersing aids, modifiers, vulcanizing agents, vulcanizing aids, and/or processing aids). etc.) may be included. As described above, the elastic member 12 normally contains carbon such as carbon black as a reinforcing material. In this embodiment, the inorganic layer 16 also suppresses deterioration of the elastic member 12 . Therefore, it is possible to suppress the carbon from easily coming into contact with each other due to the deterioration of the elastic member, thereby suppressing the deterioration of the insulating property of the elastic member and suppressing the occurrence of leakage current between the anode lead and the cathode lead. can.

The elastic member 12 has a shape corresponding to the shape of the opening of the case 11 (for example, a disc shape such as a disk shape).

The inorganic layer 16 is made of inorganic materials (or inorganic compounds) such as oxides, nitrides, and carbides. These materials have high heat resistance and easily form a dense inorganic layer 16, so that the inorganic layer 16 has high gas barrier properties. In addition, since these inorganic materials have high thermal conductivity and high heat dissipation, the effect of suppressing thermal deterioration of the elastic member 12 can be enhanced. Furthermore, these inorganic materials also have high insulating properties, which is advantageous in suppressing the occurrence of leakage current between leads. The inorganic layer may contain one kind of these inorganic materials, or two or more kinds thereof.

The thermal conductivity of the inorganic material is preferably higher than the thermal conductivity of the elastic polymer forming the elastic member 12 . In this case, since heat can easily escape from the inorganic layer 16 to the case 11, deterioration of the elastic member 12 can be further suppressed. In this case, the inorganic layer 16 is preferably in contact with the case 11 .

Preferably, the inorganic material is a metal compound. Metals constituting the metal compound include aluminum, titanium, tantalum, niobium, zirconium, hafnium, and silicon. The metal compound may contain one kind of these metals, or two or more kinds thereof. Among these metals, aluminum, silicon, and titanium are preferable from the viewpoint of high heat resistance and easy formation of a dense inorganic layer. When the inorganic material contains these metals, it is easy to ensure high thermal conductivity.

Among the metal compounds, examples of oxides include metal oxides containing the above metals, and examples of nitrides include metal nitrides containing the above metals. Silicon carbide and the like are preferable as the carbide. Among these inorganic compounds, oxides and nitrides are preferable from the viewpoint of facilitating film formation of the inorganic layer 16 and ensuring high gas barrier properties. Among them, the oxide is preferably at least one selected from the group consisting of alumina, titania and silica, and the nitride is preferably at least one selected from the group consisting of silicon nitride and aluminum nitride.

Although the thickness of the inorganic layer 16 is not particularly limited, it is, for example, 0.5 nm or more and 10 μm or less. Considering the followability of the shape change of the sealing member at the time of sealing or reflow, the thickness of the inorganic layer 16 is preferably 10 nm or more and 10 μm or less (for example, 10 nm or more and 1 μm or less), and is 50 nm or more and 1 μm or less, or 50 nm or more and 200 nm or less. is more preferred. When the thickness of the inorganic layer 16 is within such a range, it is advantageous in terms of ensuring a high gas barrier property as well as less influence on product dimensions due to a change in the shape of the sealing member.

In this specification, the thickness of the inorganic layer is determined by taking a cross-sectional image of the inorganic layer with a transmission electron microscope (TEM) and averaging the thickness of arbitrary 10 points of the cross section of the inorganic layer in the TEM image. be able to.

(Case 11)
Examples of materials for case 11 that accommodates capacitor element 10 include metals such as aluminum, stainless steel, copper, iron, and brass, and alloys thereof. After accommodating capacitor element 10, the opening of case 11 is sealed with a sealing member (or elastic member). The case 11 has a tubular shape such as a cylindrical shape, and may have a bottom portion as shown in the drawing. When using a bottomed case, one opening may be sealed with a sealing member. In addition, when both ends of the cylindrical case (that is, both ends in the length direction (or axial direction) of the cylindrical case) are open, both openings may be sealed with a sealing member. .

After the capacitor element 10 is housed in the case 11 and the elastic member 12 of the sealing member is fitted into the opening of the case 11, the case 11 is pressed against the side surface 12c of the elastic member 12 with its diameter reduced. Become. Due to this diameter reduction, the sealing member can be fixed and the sealing performance between the elastic member 12 and the side wall of the case 11 can be improved. The diameter reduction is performed by drawing the cylindrical case 11 from the outside to the side surface 12c of the elastic member 12 (specifically, lateral drawing).

If the diameter of the case 11 is reduced with respect to the side surface 12c of the elastic member 12 at the portion where the elastic member 12 is fitted, the outer diameter of the case 11 will be smaller at the reduced diameter region 11a than at other portions. Become. A region corresponding to the side surface 12c of the elastic member 12 and having a smaller outer diameter than other portions of the case 11 is referred to as a diameter-reduced region.

(lead)
The type and shape of the lead are not particularly limited, and known leads used in electrolytic capacitors can be used without particular limitation. Examples of lead materials include copper, copper alloys, aluminum, and aluminum alloys.

An inorganic layer 19 may be formed on the surfaces of the leads (lead wires 14A, 14B, lead tabs 15A, 15B) and/or the surface of the case 11 . The composition of the inorganic layer 19 may be the same as or different from the composition of the inorganic layer 16 .

The inorganic material forming the inorganic layer 19 may be selected from those described for the inorganic layer 16 . The thickness of inorganic layer 19 can also be selected from the range described for inorganic layer 16 .

(Capacitor element 10)
Capacitor element 10 includes an anode portion having a dielectric layer (chemical conversion film), a cathode portion, a separator interposed between the anode portion and the cathode portion, and an electrolyte in contact with the dielectric layer.

(Anode part)
Examples of the anode part include a metal foil and a sintered metal having a roughened surface. The type of metal that constitutes the anode portion is not particularly limited, but valve-acting metals such as aluminum, tantalum, niobium, and titanium, or alloys containing valve-acting metals can be used because the formation of the dielectric layer is easy. preferable.

Roughening of the metal foil surface can be performed by a known method. A plurality of irregularities are formed on the surface of the metal foil by roughening. Roughening is preferably performed by etching the metal foil, for example. The etching treatment may be performed by, for example, a DC electrolysis method or an AC electrolysis method.

(dielectric layer)
A dielectric layer is formed on the surface of the anode section. Specifically, since the dielectric layer is formed on the roughened surface of the metal foil, it is formed along the inner wall surfaces of the holes and depressions (pits) on the surface of the anode portion.

Although the method of forming the dielectric layer is not particularly limited, it can be formed by chemically treating the anode portion. The chemical conversion treatment may be performed, for example, by immersing the metal foil in a chemical conversion solution such as an ammonium adipate solution. In the chemical conversion treatment, if necessary, voltage may be applied while the metal foil is immersed in a chemical conversion solution.

Generally, from the viewpoint of mass production, a metal foil made of a large-sized valve metal or the like is subjected to roughening treatment and chemical conversion treatment. In that case, the anode part with the dielectric layer formed thereon is prepared by cutting the treated foil to the desired size.

(cathode)
A metal foil, for example, is used for the cathode portion. Although the type of metal is not particularly limited, it is preferable to use a valve-acting metal such as aluminum, tantalum, or niobium, or an alloy containing a valve-acting metal. The cathode portion may be roughened and/or chemically treated as necessary. Surface roughening and chemical conversion treatment can be performed, for example, by the method described for the anode portion.

(separator)
The separator is not particularly limited, and for example, a nonwoven fabric containing fibers of cellulose, polyethylene terephthalate, vinylon, polyamide (eg, aromatic polyamide such as aliphatic polyamide and aramid) may be used.

(Electrolytes)
An electrolytic capacitor may comprise an electrolyte. As the electrolyte, an electrolytic solution or a solid electrolyte can be used, and the solid electrolyte and the electrolytic solution may be used together.

Solid electrolytes include, for example, manganese compounds and conductive polymers. Examples of conductive polymers that can be used include polypyrrole, polythiophene, polyaniline, and derivatives thereof. A solid electrolyte containing a conductive polymer can be formed, for example, by chemically and/or electrolytically polymerizing raw material monomers on a dielectric layer. Alternatively, it can be formed by applying a solution in which a conductive polymer is dissolved or a dispersion in which a conductive polymer is dispersed to the dielectric layer.

The electrolyte may be a non-aqueous solvent or a mixture of a non-aqueous solvent and an ionic substance (solute, for example, an organic salt) dissolved therein. The non-aqueous solvent may be an organic solvent or an ionic liquid. Examples of non-aqueous solvents that can be used include ethylene glycol, propylene glycol, sulfolane, γ-butyrolactone, and N-methylacetamide. Examples of organic salts include trimethylamine maleate, triethylamine borodisalicylate, ethyldimethylamine phthalate, mono-1,2,3,4-tetramethylimidazolinium phthalate, mono-1,3-dimethyl-2-phthalate, ethylimidazolinium and the like.

[Manufacturing method of electrolytic capacitor]
The electrolytic capacitor described above can be manufactured by a manufacturing method including at least a step of forming the inorganic layer 16 on at least a portion of the first main surface 12a of the elastic member 12 (inorganic layer forming step). The manufacturing method may include a step of housing capacitor element 10 in case 11 and a step of sealing the opening. The manufacturing method may further include a step of preparing capacitor element 10, and the like.
Each step will be described in more detail below.

(Step of preparing capacitor element 10)
Capacitor element 10 can be fabricated (or prepared) by a known method. For example, the capacitor element 10 is produced by stacking an anode portion and a cathode portion on which a dielectric layer is formed, with a separator interposed therebetween, and then forming a solid electrolyte layer between the anode portion and the cathode portion. good too. By winding the anode portion and the cathode portion on which the dielectric layer is formed, with a separator interposed therebetween, a wound body as shown in FIG. 2 is formed, and a solid electrolyte layer is formed between the anode portion and the cathode portion. may be made by forming When forming the wound body, the lead wires 14A and 14B may be erected from the wound body as shown in FIG. 2 by winding the lead tabs 15A and 15B.

Of the anode portion, the cathode portion and the separator, the outermost layer of the wound body (the cathode portion 22 in FIG. 2) is fixed at the end of the outer surface with a winding stop tape. When the anode portion is prepared by cutting a large-sized metal foil, the capacitor element 10 in a wound state or the like is subjected to a chemical conversion treatment in order to provide a dielectric layer on the cut surface of the anode portion. may be performed.

(Step of housing capacitor element 10 in case 11)
The prepared capacitor element 10 is accommodated in the case 11 .
When using an electrolytic solution, the electrolytic solution may be accommodated in the case 11 in this step.
When the capacitor element 10 is subjected to the chemical conversion treatment, the capacitor element 10 may be accommodated in the case 11 in this step.

(Sealing process)
In this step, the opening of the case 11 containing the capacitor element 10 is sealed with the sealing member 17 or the elastic member 12 . More specifically, the elastic member 12 is fitted into the opening of the case 11 so that the first main surface 12a of the elastic member 12 is arranged on the opening side of the case 11 . At this time, the elastic member 12 fitted in the opening of the case 11 may be the elastic member 12 before the inorganic layer 16 is formed, or the elastic member 12 after the inorganic layer 16 is formed (that is, the sealing member 17 is provided). It may be the elastic member 12 .

After fitting the elastic member 12 into the opening of the case 11, the open end of the case 11 is crimped against the elastic member 12 (or the sealing member 17) so that the open end is directly or indirectly attached to the elastic member 12. It is pressed and thereby sealed. At this time, the open end may be subjected to curling or the like as necessary. Further, the vicinity of the open end of the case 11 may be subjected to drawing as necessary.
The case 11 may be reduced in diameter as necessary.

When the elastic member 12 has the through hole 18 , the lead connected to the capacitor element 12 passes through the through hole 18 and is pulled out from the second main surface 12 b side of the elastic member 12 to the first main surface 12 a side. The elastic member 12 is fitted into the opening of the case 11 so as to be.

(Inorganic layer forming step)
The inorganic layer forming step may be performed before or after the sealing step (more specifically, fitting the elastic member 12 into the opening of the case 11). When forming the inorganic layer 16 before the sealing process, in the sealing process, the opening of the case 11 is sealed using the elastic member 12 (that is, the sealing member 17) on which the inorganic layer 16 is formed. When forming the inorganic layer 16 after the sealing process, in the sealing process, the opening of the case 11 is sealed using the elastic member 12 on which the inorganic layer 16 is not formed, and the opening of the case 11 is fitted. A sealing member 17 is formed by forming the inorganic layer 16 on the elastic member 12 . Further, the inorganic layer 16 may be formed after the opening of the case 11 is sealed using the sealing member 17 having the inorganic layer 16 .

When the inorganic layer 16 is formed before the sealing step, the inorganic layer 16 may be formed on the elastic member 12 (Method A), the inorganic layer 16 is formed on the precursor sheet of the elastic member 12, and the sealing member 17 is formed. You may cut out (Method B). Since the inorganic layer 16 can be formed on both the elastic member 12 and the precursor sheet in this way, the selectivity in forming the inorganic layer is high, which is advantageous in terms of increasing productivity.

In the case of method A, a precursor sheet for the elastic member 12 is cut into the shape of the elastic member 12 and the inorganic layer 16 is formed on at least the first main surface 12 . When the inorganic layer 16 is formed by a vapor phase method such as ALD, the inorganic layer 16 is likely to be formed on the entire exposed surface of the elastic member 12. Therefore, as shown in FIG. An inorganic layer 16 is formed on the two main surfaces 12b, the side surfaces 12c, and the wall surfaces 12d of the through holes 18. As shown in FIG. When the inorganic layer 12 is formed on the elastic member 12 by the vapor phase method, a region where the inorganic layer 16 is not desired may be masked.

In the case of method B, the inorganic layer forming step includes preparing a precursor sheet, forming the inorganic layer 16 on at least part of the main surface of the precursor sheet corresponding to the first main surface of the elastic member 12, and forming the inorganic layer 16. a step of cutting out a sealing member from the preformed sheet. If the through-holes 18 are formed in the precursor sheet before forming the inorganic layer 16, the inorganic layer 16 can also be formed on the walls of the through-holes 18 when forming the inorganic layer 16, as shown in FIG. After forming the inorganic layer 16 on the first main surface of the precursor sheet or on the first main surface and the second main surface, if the through holes 18 are formed, as shown in FIGS. , the inorganic layer 16 is not formed.

When the inorganic layer forming step is performed after the step of fitting the elastic member 12 into the opening of the case 11, the inorganic layer 16 is formed on the portion of the first main surface of the elastic member 12 exposed from the opening of the case 11. . When the inorganic layer 16 is formed by a vapor phase method such as ALD, the inorganic layer 19 is also formed on the outer surface of the case 11 and the surfaces of the leads as shown in FIG. If necessary, when forming the inorganic layer 16 or the inorganic layer 19, a region where the inorganic layer is not desired to be formed may be masked.

The inorganic layer may be formed, for example, by attaching an inorganic compound that forms the inorganic layer to the elastic member 12 or the precursor sheet, and exposing the raw material of the inorganic compound to an atmosphere containing an oxidizing agent, a nitriding agent, or the like. may be formed by The inorganic layer may be formed by a liquid phase method, but is preferably formed by a vapor phase method from the viewpoint of forming a more uniform inorganic layer even if the thickness is small. From the viewpoint of suppressing thermal deterioration of the elastic polymer when forming the inorganic layer, the inorganic layer is preferably formed in an atmosphere of, for example, 200° C. or lower (preferably 120° C. or lower).

Examples of the liquid phase method include a precipitation method and a sol-gel method. Vapor phase methods include, for example, physical vapor deposition (PVD), chemical vapor deposition (CVD), sputtering, and ALD. PVD and CVD are usually performed at a temperature higher than 200°C, but the sputtering method and ALD method can form an inorganic layer in an atmosphere of 200°C or lower, further 120°C or lower. From the viewpoint of suppressing thermal deterioration of the elastic polymer when forming the inorganic layer, it is preferable to form the inorganic layer by a sputtering method or an ALD method. The sputtering method and the ALD method (particularly, the ALD method) can ensure high coverage and form a more uniform inorganic layer. Among the sputtering methods, ultra-vacuum (MPS) sputtering can perform sputtering at a relatively low temperature and can also form a silicon nitride film having excellent film properties. Therefore, the effect of reducing or suppressing the contact of oxygen to the elastic member 12 can be further enhanced.

In the ALD method, metal compounds with high vapor pressure (for example, organometallic compounds and metal halides) are used as raw materials for inorganic compounds. Vaporizing such a raw material allows the molecular raw material to interact with the surface of the elastic member 12 . Even if unevenness or gaps exist in the elastic member 12, leads, case, or contact portions thereof, the molecular raw material can easily reach deep into the recesses or gaps, and easily form a homogeneous inorganic layer.

In the ALD method, for example, an inorganic layer is formed on the surface of the elastic member 12 or the precursor sheet by the following procedure.
First, an object (elastic member 12, precursor sheet, electrolytic capacitor (precursor) in which the opening of the case 11 is sealed with the elastic member 12, etc.) with at least the first main surface 12a exposed is accommodated. A gaseous first raw material (organometallic compound, metal halide, etc.) is introduced into the reaction chamber. Thereby, the object is exposed to the atmosphere containing the first raw material. After that, when the surface of the object is covered with a monomolecular layer of the first raw material, a self-terminating mechanism due to the organic groups and halogen atoms of the first raw material works, and the first raw material beyond that is adsorbed on the surface of the object. Gone. Excess first source material is purged with an inert gas or the like and removed from the reaction chamber.

Next, a gaseous second raw material is introduced into the reaction chamber containing the object. Thereby, the object is exposed to an atmosphere containing the second raw material, and a reaction between the monomolecular layer of the first raw material and the second raw material occurs. When this reaction is finished, no more second raw material is adsorbed on the surface of the object. Excess second source material is purged with an inert gas or the like and removed from the reaction chamber.

As described above, by repeating a series of operations consisting of introduction of the first raw material, purging, introduction of the second raw material, and purging, an inorganic compound is generated on the surface of the object, thereby forming a film of the inorganic compound. An inorganic layer is formed.

The inorganic layer can also be formed on the surface of the object by repeating a series of operations of introducing the first raw material and the second raw material into the reaction chamber and purging. If necessary, repeating the introduction of the first raw material and the second raw material and purging may be combined with repeating the introduction of the first raw material, the purge, the introduction of the second raw material, and the purging.

The first raw material is not particularly limited, and an appropriate metal compound may be selected according to the type of inorganic layer desired. Examples of the first raw material include metal compounds (organometallic compounds and/or metal halides, etc.) containing at least one metal selected from the group consisting of aluminum, titanium, tantalum, niobium, zirconium, hafnium, and silicon. be done. Various organometallic compounds and metal halides conventionally used in the ALD method may be used as the first raw material.

Organometallic compounds include compounds having the above metal and an organic group. Examples of organic groups include hydrocarbon groups (e.g., alkyl groups, cycloalkyl groups, cyclopentadienyl groups, etc.), nitrogen-containing organic groups (e.g., organic amino groups, amide groups, imide groups, etc.), oxygen-containing organic groups (e.g., For example, an alkoxy group, a carbonyl group, an ester group, etc.). The organometallic compound may have one or more of these organic groups. The organometallic compound may additionally have halogen atoms (eg, fluorine, chlorine, bromine, and/or iodine).

Halogen atoms contained in metal halides include fluorine, chlorine, bromine, and/or iodine. Specific examples of metal halides include titanium tetrachloride, silicon tetrachloride, silicon tetrabromide, and hafnium tetrachloride.

As the second raw material, an oxidizing agent, a nitriding agent, or the like is used according to the type of the inorganic compound forming the inorganic layer. The oxidizing agent includes water (water vapor), oxygen, ozone, and the like. Examples of nitriding agents include nitrogen and ammonia. If necessary, hydrogen or the like may be used together. As for the second raw material, one kind may be used, or two or more kinds may be used in combination, if necessary.

In addition, you may use 3 or more types of raw materials. That is, one or more raw materials may be used in addition to the first raw material and the second raw material. For example, a series of operations consisting of introducing a first raw material, purging, introducing a second raw material, purging, introducing a third raw material different from the first raw material and the second raw material, and purging may be repeated.

When the inorganic layer 16 is formed on the precursor sheet, the sealing member 17 is cut out in the inorganic layer forming step. The cutting of the sealing member 17 is not particularly limited, and can be performed by a known method.

In the above embodiment, a wound type electrolytic capacitor has been described, but the scope of application of the present invention is not limited to the above. It can also be applied to chip-type electrolytic capacitors and laminated-type electrolytic capacitors using metal plates instead of anode foils.

INDUSTRIAL APPLICABILITY The present invention can be used for electrolytic capacitors (hybrid electrolytic capacitors, solid electrolytic capacitors, etc.) having a sealing member.

10: capacitor element, 11: bottomed case, 12: elastic member, 12a: first main surface, 12b: second main surface, 12c: side surface, 12d: wall surface of through hole, 13: seat plate, 14A, 14B: Lead wire, 15A, 15B: lead tab, 16: inorganic layer, 17: sealing member, 18: through hole, 19: inorganic layer, 21: anode foil, 22: cathode foil, 23: separator, 24: winding stop tape

Claims (5)

A method for manufacturing an electrolytic capacitor comprising a capacitor element, a case having an opening for housing the capacitor element, and a sealing member for sealing the opening,
The electrolytic capacitor includes lead wires drawn out from the capacitor element,
The sealing member comprises an elastic member having a first main surface arranged on the opening side,
the elastic member has a through hole through which the lead passes;
In the manufacturing method, the first main surfaceand said through holeEquipped with an inorganic layer forming step of forming an insulating inorganic layer in
housing the capacitor element in the case;
placing the first main surface on the opening side of the opening of the case, and crimping the elastic member in a state in which the lead is pulled out from the through hole;
After the step of crimping the elastic member, the inorganic layer forming step is performed by an atomic layer deposition method. A method for manufacturing an electrolytic capacitor. 2. The method of manufacturing an electrolytic capacitor according to claim 1, wherein said inorganic layer is formed on the outer surface of said case. . 3. The method of manufacturing an electrolytic capacitor according to claim 1, wherein said inorganic layer is formed on the surface of said lead. 4. The method of manufacturing an electrolytic capacitor according to claim 3, wherein said inorganic layer formed on said first main surface, said case and said leads are integrally formed. 3. The method of manufacturing an electrolytic capacitor according to claim 1, wherein said inorganic layer is formed at a temperature of 120[deg.] C. or less.

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