Electrolytic capacitor

Abstract

This electrolytic capacitor comprises: a bottomed case that has an opening; a capacitor element and an electrolytic solution that are accommodated in the bottomed case; and a sealing body that contains an elastic polymer and seals the opening. The electrolytic solution contains an organic solvent, an acid component, a base component, and water. The organic solvent mainly contains a first solvent having a boiling point of 200°C to 300°C. The acid component includes a carboxylic acid compound. The base component includes at least one selected from the group consisting of an organic base and ammonia. The mass of the water per unit volume inside the electrolytic capacitor is 0.003 mg / mm3 or more. The total mass of the acid component and base component per unit volume inside the electrolytic capacitor is 0.008 mg / mm3 to 0.050 mg / mm3.

Description

Electrolytic capacitors Cross-reference of related applications

[0001] This disclosure claims priority rights to Japanese Patent Application No. 2024-231258, filed with the Japan Patent Office on 26 December 2024, and the entirety of the said patent application is incorporated herein by reference.

[0002] This disclosure relates to electrolytic capacitors.

[0003] An electrolytic capacitor comprises, for example, a bottomed case having an opening, a capacitor element and electrolyte housed within the bottomed case, and a sealant containing an elastic polymer that seals the opening. As the electrolyte, for example, a solution obtained by dissolving a solute in an organic solvent is used. The capacitor element includes, for example, an anode foil on which a dielectric layer is formed, and a cathode portion in contact with at least a part of the dielectric layer.

[0004] Patent Document 1 proposes that, in an aluminum electrolytic capacitor, a sealing member is used which is made by mixing 100 parts by weight of elastic polymer with 50 to 200 parts by weight of filler, 10 to 80 parts by weight of carbon black as a reinforcing agent, 0.1 to 10 parts by weight of vulcanizing agent, and 1 to 10 parts by weight of magnesium oxide, and then vulcanizing and molding these components. Furthermore, it proposes that the driving electrolyte uses γ-butyrolactone as the main solvent and a salt of a carboxylic acid of a quaternary compound having an N,N,N'-substituted amidine group as the electrolyte.

[0005] Patent document 2 proposes using an elastic member containing an elastic polymer and a specific hindered phenol compound as a sealing member for an energy storage device.

[0006] Japanese Patent Publication No. 11-274011, International Publication No. 2019 / 065950

[0007] One aspect of the present disclosure is an electrolytic capacitor comprising a bottomed case having an opening, a capacitor element and an electrolyte housed in the bottomed case, and a sealant containing an elastic polymer that seals the opening, wherein the electrolyte comprises an organic solvent, an acid component, a basic component, and water, the organic solvent mainly comprises a first solvent having a boiling point of 200°C or more and 300°C or less, the acid component comprises a carboxylic acid compound, the basic component comprises at least one selected from the group consisting of organic bases and ammonia, and the mass of water per unit volume inside the electrolytic capacitor is 0.003 mg / mm³. ３ The above is true, and the total mass of the acidic component and the base component per unit volume inside the electrolytic capacitor is 0.008 mg / mm³. ３ 0.050mg / mm or more ３ The following concerns electrolytic capacitors.

[0008] According to this disclosure, it is possible to provide an electrolytic capacitor that can be stably mounted on a substrate.

[0009] This is a schematic cross-sectional view of an electrolytic capacitor according to one embodiment of the present disclosure. This is a schematic diagram showing a portion of the capacitor element of the electrolytic capacitor in Figure 1 unfolded. This is a graph showing the relationship between the total mass of acid and base components per unit volume inside the electrolytic capacitor and the average swelling of the sealant for the electrolytic capacitors of the examples and comparative examples.

[0010] Novel features of the present invention are described in the appended claims, but the present invention, both in terms of structure and content, and in conjunction with other objects and features of the present invention, will be better understood by the following detailed description in conjunction with the drawings.

[0011] Electrolytic capacitors are mounted onto circuit boards, for example, by reflow soldering. Depending on the application of the electrolytic capacitor, relatively stringent conditions may be required for the reflow soldering process. In this case, the internal pressure of the electrolytic capacitor may rise, causing the encapsulation to bulge and easily impairing its mountability on the circuit board.

[0012] In electrolytic capacitors, a low moisture content is required to ensure stable capacitor performance. However, it is difficult to keep the moisture content low because moisture can be mixed into the electrolyte or generated by side reactions. If a large amount of moisture is present inside the electrolytic capacitor, it will vaporize during reflow soldering, increasing the internal pressure of the electrolytic capacitor.

[0013] Furthermore, organic solvents with a boiling point between 200°C and 300°C (hereinafter sometimes referred to as the first solvent) have been thought to have less vaporization during reflow and less impact on internal pressure compared to organic solvents with a boiling point below 200°C, such as ethylene glycol. However, in applications such as high-density mounting of electronic components on a substrate, electrolytic capacitors are sometimes required to undergo reflow processing under relatively severe conditions. When electrolytic capacitors are exposed to high temperatures during reflow processing, or heated for a relatively long period of time even at a temperature of around 200°C, the amount of vaporization increases even in the first solvent, which has a relatively high boiling point. In addition, acidic and basic components contained in the electrolyte gasify through decomposition, etc. As a result, the internal pressure of the electrolytic capacitor increases significantly. When the internal pressure increases significantly, the sealing part containing the elastic polymer swells, making it impossible to mount the electrolytic capacitor on the substrate, and reducing mounting stability.

[0014] Technical (1) In view of the above, an electrolytic capacitor according to one aspect of the present disclosure comprises a bottomed case having an opening, a capacitor element and an electrolyte housed in the bottomed case, and a sealant containing an elastic polymer that seals the opening. The electrolyte contains an organic solvent, an acid component, a basic component, and water. The organic solvent mainly contains an organic solvent (first solvent) having a boiling point of 200°C or more and 300°C or less. The acid component contains a carboxylic acid compound. The basic component contains at least one selected from the group consisting of organic bases and ammonia. The mass of water per unit volume inside the electrolytic capacitor is 0.003 mg / mm³. ３ That concludes the report. The total mass of the acidic and base components per unit volume inside the electrolytic capacitor is 0.008 mg / mm³. ３ 0.050mg / mm or more ３ The following applies:

[0015] The electrolytic solution contains moisture with a mass of 0.003 mg / mm or more per unit volume inside the electrolytic capacitor, a first solvent, the acid component described above, and the base component described above. In this case, when performing a reflow process on the electrolytic capacitor under relatively severe conditions, the evaporation amounts of the moisture and the first solvent are large, the acid component and the base component are easily decomposed, and the amount of generated gas increases. As a result, the increase in the internal pressure of the electrolytic capacitor becomes significant, the sealing body portion containing the elastic polymer bulges, and it becomes difficult to stably mount on the substrate. In contrast, in the present disclosure, the total mass of the acid component and the base component per unit volume inside the electrolytic capacitor is 0.008 mg / mm or more and 0.050 mg / mm or less. With this feature, even under conditions where the evaporation amounts and the gas generation amounts of the components contained in the electrolytic solution tend to increase as described above, an increase in the internal pressure during reflow can be suppressed, and bulging of the sealing body can be suppressed. As a result, even when the electrolytic capacitor is subjected to a reflow process under relatively severe conditions, the electrolytic capacitor can be stably mounted on the substrate. ３ The electrolytic solution contains moisture with a mass of 0.003 mg / mm or more per unit volume inside the electrolytic capacitor, a first solvent, the acid component described above, and the base component described above. In this case, when performing a reflow process on the electrolytic capacitor under relatively severe conditions, the evaporation amounts of the moisture and the first solvent are large, the acid component and the base component are easily decomposed, and the amount of generated gas increases. As a result, the increase in the internal pressure of the electrolytic capacitor becomes significant, the sealing body portion containing the elastic polymer bulges, and it becomes difficult to stably mount on the substrate. In contrast, in the present disclosure, the total mass of the acid component and the base component per unit volume inside the electrolytic capacitor is 0.008 mg / mm or more and 0.050 mg / mm or less. With this feature, even under conditions where the evaporation amounts and the gas generation amounts of the components contained in the electrolytic solution tend to increase as described above, an increase in the internal pressure during reflow can be suppressed, and bulging of the sealing body can be suppressed. As a result, even when the electrolytic capacitor is subjected to a reflow process under relatively severe conditions, the electrolytic capacitor can be stably mounted on the substrate. ３ or more and 0.050 mg / mm ３ or less. With this feature, even under conditions where the evaporation amounts and the gas generation amounts of the components contained in the electrolytic solution tend to increase as described above, an increase in the internal pressure during reflow can be suppressed, and bulging of the sealing body can be suppressed. As a result, even when the electrolytic capacitor is subjected to a reflow process under relatively severe conditions, the electrolytic capacitor can be stably mounted on the substrate.

[0016] "Mainly containing the first solvent" for the organic solvent means that the mass ratio of the first solvent is the largest among all the organic solvents contained in the electrolytic solution.

[0017] The internal volume of the electrolytic capacitor means the internal volume (unit: mm ３ ) surrounded by the bottomed case and the sealing body in the electrolytic capacitor. More specifically, the internal volume of the electrolytic capacitor is the volume (unit: mm ３ ) of the portion surrounded by the inner surface of the bottomed case and the inner surface of the sealing body. This volume is obtained by the following procedure. First, X-ray photographs are taken respectively through the center in the vertical direction and the center in the horizontal direction of the electrolytic capacitor, and the height h (unit: mm) from the inner bottom surface of the case to the inner bottom surface of the sealing body and the area S (unit: mm ２)(=S×h). By multiplying these measured values, the internal volume of the electrolytic capacitor can be obtained. By dividing the total mass (unit: mg) of the acid component and the base component contained in the electrolytic capacitor by the internal volume of the electrolytic capacitor, the total mass (mg / mm ３ ) of the acid component and the base component per unit volume inside the electrolytic capacitor is obtained. The total mass of the acid component and the base component is obtained from the mass of the electrolytic solution contained in the electrolytic capacitor and the concentrations of the acid component and the base component in the electrolytic solution. The mass of the electrolytic solution is obtained by recovering and weighing the electrolytic solution from the electrolytic capacitor. In accordance with the case of the acid component and the base component, the concentration of water is obtained from the electrolytic solution, and the mass of water contained in the electrolytic solution is obtained from the mass of the electrolytic solution and the concentration of water. The acid component, the base component, and water in the electrolytic solution are identified using gas chromatography mass spectrometry (GC-MS) or liquid chromatography mass spectrometry (LC-MS), etc., and the concentrations of each component are obtained. The measurement of volume, the analysis of water, the acid component, and the base component are performed on the initial electrolytic capacitor.

[0018] In this specification, the initial electrolytic capacitor is an unused electrolytic capacitor if it is an electrolytic capacitor after aging or conditioning charge and discharge or a commercially available product.

[0019] Technology (2) In the above technology (1), it is preferable that the first solvent contains at least one selected from the group consisting of a lactone compound and a sulfone compound. When these first solvents are subjected to a reflux treatment for a certain period of time even at a temperature of about 200 °C, for example, they vaporize and the internal pressure of the electrolytic capacitor increases. In the present disclosure, the total mass of the acid component and the base component per unit volume inside the electrolytic capacitor is within a specific range. Thereby, an increase in the internal pressure of the electrolytic capacitor during reflux when using the above first solvent can be suppressed, and mounting on a substrate can be stably performed.

[0020] Technology (3) In the above technology (1) or technology (2), the mass of the water per unit volume inside the electrolytic capacitor is 0.003 mg / mm ３ or more and 0.025 mg / mm ３The following is preferable. In this case, although moisture vaporizes due to the reflow process and the internal pressure is likely to increase, by setting the total mass of the acid component and the base component per unit volume inside the electrolytic capacitor within a specific range, the electrolytic capacitor can be stably mounted on the substrate. In addition, since the viscosity of the electrolytic solution is kept low and precipitation of the acid component, the base component, or salts thereof is suppressed, high capacitor performance can be easily obtained.

[0021] Technique (4) In any one of the above techniques (1) to (3), the elastic polymer contains butyl rubber. When using a sealing body containing butyl rubber, it is easy to seal the electrolytic capacitor with high airtightness. However, when the internal pressure increases, the sealing body is likely to bulge. In the present disclosure, since the increase in the internal pressure is suppressed, even when the sealing body contains butyl rubber, the electrolytic capacitor can be stably mounted on the substrate.

[0022] Technique (5) In any one of the above techniques (1) to (4), the electrolytic capacitor is suitable for use in applications that require a reflow process at a temperature of 200°C or higher for 80 seconds or longer. Under such reflow conditions, thermal stress is likely to be applied to the electrolytic capacitor. Therefore, not only does moisture vaporize, but also vaporization of the first solvent and decomposition of the acid component and the base component are likely to occur, and the internal pressure of the electrolytic capacitor is likely to increase. In the present disclosure, even under such reflow conditions, since the increase in the internal pressure of the electrolytic capacitor is suppressed, it is particularly suitable for the above applications.

[0023] Technique (6) In the above technique (5), the electrolytic capacitor is particularly suitable for use in applications that require at least two-stage reflow processing, namely a first reflow process with a peak temperature of 200°C or higher and less than 240°C and a second reflow process with a peak temperature of 240°C or higher and 300°C or lower. When the reflow process is performed in multiple stages, thermal stress is likely to be applied to the electrolytic capacitor. In the electrolytic capacitor of the present disclosure, even when the reflow process is performed in multiple stages under the above conditions, bulging of the electrolytic capacitor is suppressed and it can be stably mounted on the substrate.

[0024] Technical (7) In the above technical (6), the time for the second reflow process is preferably 20 seconds or more. When the second reflow process is performed at a high temperature for 20 seconds or more, the electrolytic capacitor is prone to thermal stress. In the electrolytic capacitor of this disclosure, even when the reflow process is performed in multiple stages under the above conditions, swelling of the electrolytic capacitor is suppressed and it can be stably mounted on the substrate.

[0025] The electrolytic capacitor of this disclosure will be described in more detail below, including the above-mentioned technologies (1) to (7), with reference to the drawings as necessary. Within the limits of what is technically consistent, at least one of the above-mentioned technologies (1) to (7) may be combined with at least one of the elements described below. Note that the figures are schematic representations, and the dimensions (e.g., thickness) of each component may differ from those of the actual components.

[0026] [Electrolytic Capacitor] An electrolytic capacitor comprises a bottomed case having an opening, a capacitor element and electrolyte housed in the bottomed case, and a sealant that seals the opening. An electrolytic capacitor comprises at least one capacitor element.

[0027] (Electrolyte) The electrolyte contains an organic solvent, an acid component, a basic component, and water. The electrolyte may also contain known additives as needed.

[0028] (Organic solvent) Examples of organic solvents include non-aqueous solvents. It is preferable to use at least a polar solvent as the organic solvent. Polar solvents include aprotic polar solvents and protic polar solvents. Examples of such organic solvents include sulfone compounds, lactone compounds, carbonate compounds, and alcohol compounds. The electrolyte may contain one of these organic solvents or a combination of two or more. It is preferable that the organic solvent is liquid at a temperature of 20°C to 40°C.

[0029] In this disclosure, the organic solvent mainly comprises a first solvent. The first solvent is an organic solvent with a boiling point of 200°C or higher and 300°C or lower. The first solvent is preferably an aprotic polar solvent. Examples of the first solvent include lactone compounds, sulfone compounds, and carbonate compounds.

[0030] Examples of lactone compounds include γ-butyrolactone (GBL, boiling point 204°C) and γ-valerolactone (boiling point approximately 207°C). As for sulfone compounds, cyclic sulfone compounds are preferred. Examples of cyclic sulfone compounds include sulfolane (SL, boiling point 285°C). As for carbonate compounds, cyclic carbonate compounds are preferred. Examples of cyclic carbonate compounds include ethylene carbonate (boiling point 243°C) and propylene carbonate (boiling point 242°C).

[0031] The electrolyte may contain one first solvent or a combination of two or more solvents. Preferably, the first solvent contains at least one selected from the group consisting of lactone compounds and sulfone compounds.

[0032] The organic solvent may include an organic solvent other than the first solvent (sometimes referred to as the second solvent). The second solvent may be an organic solvent that is liquid at temperatures between 20°C and 40°C. The boiling point of the second solvent may be less than 200°C or higher than 300°C. The second solvent may be an aprotic solvent or a protic solvent.

[0033] Examples of the second solvent include linear carbonate compounds (dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, etc.), sulfoxide compounds (dimethyl sulfoxide, diethyl sulfoxide, etc.), and alcohol compounds. Alcohol compounds, which are protic polar solvents, include monohydric alcohols and polyhydric alcohols. Examples of polyhydric alcohols include glycol compounds, glycerol compounds (glycerol, polyglycerol, etc.), sugar alcohol compounds, or alkylene oxide adducts thereof (ethylene oxide adducts, polyethylene oxide adducts, etc.). Examples of glycol compounds include alkylene glycols (ethylene glycol (EG), propylene glycol, etc.) and polyalkylene glycols (polyethylene glycol (PEG), polypropylene glycol, etc.). The electrolyte may contain one second solvent or two or more. The electrolyte may contain the first solvent and a protic solvent as the second solvent. The number-average molecular weight of polyalkylene glycol is preferably 200 to 1000, and more preferably 200 to 600.

[0034] In the organic solvent, the volume ratio of the first solvent is preferably 30% to 100% by volume, more preferably 50% to 100% by volume, and even more preferably 60% to 100% by volume. Within these ranges, the upper limit may be 80% by volume or less. The total volume ratio of the lactone compound and sulfone compound in the organic solvent may also be selected from these ranges. The volume ratio of the first solvent in the organic solvent is the value at 25°C.

[0035] (Moisture) The electrolyte contains moisture. The mass of moisture per unit volume inside an electrolytic capacitor is 0.003 mg / mm³. ３That concludes the explanation. When an electrolytic capacitor contains such a mass of moisture, swelling of the encapsulant is likely to become significant when reflow processing is performed under relatively severe conditions. In this disclosure, even in such cases, specific acid and base components are used, and the total mass of these components per unit volume inside the electrolytic capacitor is kept within a specific range. This suppresses swelling of the encapsulant and allows for stable mounting of the electrolytic capacitor. The mass of moisture per unit volume inside the electrolytic capacitor is 0.005 mg / mm³. ３ The above is preferable, and 0.008 mg / mm³ ３ 0.010 mg / mm³ or more ３ The above is more preferable. From the viewpoint of obtaining a higher effect in suppressing swelling of the sealant, the mass of water per unit volume inside the electrolytic capacitor should be 0.025 mg / mm³. ３ The following is preferred: 0.020 mg / mm³ ３ The following are preferable.

[0036] The mass of water per unit volume inside an electrolytic capacitor is 0.003 mg / mm³. ３ (or 0.005 mg / mm³) ３ or more) 0.025mg / mm ３ Below, 0.008mg / mm ３ (or 0.010 mg / mm³) ３ or more) 0.025mg / mm ３ Below, 0.003mg / mm ３ (or 0.005 mg / mm³) ３ or more) 0.020mg / mm ３ The following, or 0.008 mg / mm³ ３ (or 0.010 mg / mm³) ３ or more) 0.020mg / mm ３ The following is also acceptable.

[0037] The anode of a capacitor element generally has a dielectric coating (sometimes referred to as a dielectric layer) on its surface. If a defect occurs in the dielectric coating, leakage current occurs. If the organic solvent of the electrolyte mainly contains aprotic solvents, the repairability of the dielectric coating is low even if a defect occurs in the dielectric coating. In this disclosure, the mass of water per unit volume inside the electrolytic capacitor is 0.003 mg / mm³. ３ As a result, the dielectric film exhibits high repairability. Consequently, leakage current is suppressed, and the decrease in capacity during repeated charging and discharging is minimized.

[0038] (Acid component) The acid component includes a carboxylic acid compound (sometimes referred to as the primary acid). Examples of primary acids include carboxylic acids (aliphatic carboxylic acids, alicyclic carboxylic acids, aromatic carboxylic acids, etc.), carboxylic acid anhydrides (phthalic anhydride, pyromellitic anhydride, etc.), and coordination compounds of carboxylic acids. The primary acid may be a monocarboxylic acid compound or a polycarboxylic acid compound. From the viewpoint of relatively high heat resistance, it is preferable to use at least an aromatic carboxylic acid.

[0039] Examples of aromatic carboxylic acids include aromatic hydroxy acids (such as benzoic acid and salicylic acid), aromatic polycarboxylic acids (such as phthalic acid and pyromellitic acid), and sulfo-aromatic carboxylic acids (such as m-sulfobenzoic acid, 4-sulfophthalic acid, and 5-sulfosalicylic acid).

[0040] Examples of the coordination compounds mentioned above include a coordination compound in which at least one central atom selected from the group consisting of boron, aluminum, and silicon, and a carboxylic acid bonded to this central atom, are used. Specific examples of coordination compounds include borodisalicylic acid, borodisuoic acid, borodiglycolic acid, and borodigallic acid.

[0041] The acid component may consist of one primary acid, or it may consist of two or more acids in combination.

[0042] The acid component may include acids other than the primary acid (sometimes referred to as secondary acids). Examples of secondary acids include acids having carbonyloxy bonds other than carboxylic acids (such as oxocarbonic acid and meldrumic acid) or their coordination compounds, phenolic compounds (such as picric acid, p-nitrophenol, pyrogallol, and catechol) or their coordination compounds, sulfur-containing acids (such as sulfuric acid, sulfonic acid (such as aromatic sulfonic acid), oxyaromatic sulfonic acid (such as phenol-4-sulfonic acid)), compounds having sulfonyliimide bonds, boron-containing acids (such as boric acid, halide boric acid (such as tetrafluoroboric acid), or partial esters thereof), phosphorus-containing acids (such as phosphoric acid, halide phosphoric acid (such as hexafluorophosphate), phosphonic acid, phosphinic acid, or partial esters thereof), and nitrogen-containing acids (such as nitric acid and nitrite).

[0043] Examples of compounds containing a sulfonylimide bond include saccharin, 1,2-benzenedisulfonamide, cyclohexafluoropropane-1,3-bis(sulfonyl)imide, 4-methyl-N-[(4-methylphenyl)sulfonyl]benzenesulfonamide, dibenzenesulfonamide, trifluoromethanesulfonanilide, N-[(4-methylphenyl)sulfonyl]acetamide, benzenesulfonanilide, and N,N'-diphenylsulfamide.

[0044] Examples of the coordination compounds mentioned above include those comprising at least one central atom selected from the group consisting of boron, aluminum, and silicon, and an acid or phenol compound having a carbonyloxy bond bonded to this central atom. Specific examples of coordination compounds include borodicatechol and borodipyrogallol.

[0045] The acid component may contain one type of secondary acid, or a combination of two or more types.

[0046] In the acid component, the content of the first acid is preferably 50% by mass or more and 100% by mass or less, more preferably 70% by mass or more and 100% by mass or less, and even more preferably 85% by mass or more and 100% by mass or less. When the content of the first acid is within this range, gas is easily generated due to the decomposition of the first acid when reflow processing is performed under relatively severe conditions. In this disclosure, even under such conditions, the rise in internal pressure of the electrolytic capacitor is suppressed, swelling of the encapsulant is suppressed, and stable mounting on the substrate is possible.

[0047] The concentration of the acid component in the electrolyte is preferably 3% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 18% by mass or less, and even more preferably 3% by mass or more and 14% by mass or less. The lower limit of these ranges may be 5% by mass.

[0048] In the electrolyte, the acid groups (carboxyl groups, sulfonic acid groups, phosphate groups, phosphonic acid groups, phenolic hydroxyl groups, etc.) of the first and second acids may exist in any of the following forms: free form, salt form, anionic form, or form interacting with (compounding with) the components of the capacitor element (e.g., conductive polymer). Each of the acid groups of the first or second acid encompasses all of these forms.

[0049] (Basic component) The presence of a basic component in the electrolyte increases the dissociation of the acid component, making it easier to obtain high conductivity in the electrolyte. It also helps maintain a low pH in the electrolyte. Therefore, when the capacitor element contains a conductive polymer, the detachment of dopants from the conductive polymer is suppressed, ensuring high conductivity of the conductive polymer.

[0050] The basic component includes at least one base selected from the group consisting of organic bases and ammonia. These bases are prone to generating gas through decomposition when reflow processing is performed under relatively severe conditions. In this disclosure, even when the electrolyte contains such basic components, the rise in internal pressure of the electrolytic capacitor can be suppressed, swelling of the encapsulant can be suppressed, and the electrolytic capacitor can be stably mounted on the substrate.

[0051] Examples of organic bases include amines (specifically, primary amines, secondary amines, and tertiary amines), quaternary ammonium compounds, and amidinium compounds. The electrolyte may contain one of these bases or a combination of two or more.

[0052] The amine may be aliphatic, aromatic, or heterocyclic. Examples of amines include dialkylamines (such as diethylamine), trialkylamines (such as trimethylamine, ethyldimethylamine, triethylamine (TEA), tri-n-butylamine (TBA), and dimethyl-n-octylamine (DMOA)), alkylenediamines (such as ethylenediamine), aromatic amines (such as aniline), and heterocyclic amines (such as pyrrolidine, imidazole compounds (such as imidazole (Imd), 1,2,3,4-tetramethylimidazolinium), pyridine (Pyr), 4-dimethylaminopyridine, and diazabicycloundecene (DBU)). Both aromatic amines and heterocyclic amines may be monocyclic or polycyclic (such as fused rings or cross-linked rings). Examples of quaternary ammonium compounds include amidine compounds (including imidazole compounds).

[0053] The electrolyte may contain basic components in free form, in cation form, or in salt form. All of these forms are sometimes collectively referred to as basic components.

[0054] In this disclosure, the total mass of acidic and basic components per unit volume inside the electrolytic capacitor is 0.008 mg / mm³. ３ 0.050mg / mm or more ３ The following is the total mass: 0.008 mg / mm³. ３ Below this value, bulging of the encapsulant becomes noticeable when reflow processing is performed under relatively severe conditions, and the rate of mounting defects on the substrate increases. (Total mass of the above value is 0.050 mg / mm³) ３ If this value is exceeded, the viscosity of the electrolyte becomes excessively high, making it difficult to impregnate the capacitor elements, and causing electrolyte components to precipitate, thereby impairing the capacitor's performance. The above total mass is 0.045 mg / mm³. ３The following is preferred: 0.043 mg / mm³ ３ The following are preferable.

[0055] The equivalent ratio of the first acid to the base component (= first acid / base component) may be 0.5 or more and 10 or less, or 1.0 or more and 5.0 or less. In these cases, a high degree of dissociation of the first acid can be ensured, and corrosion of the electrode can be suppressed.

[0056] The equivalent ratio of the primary acid to the base component is calculated as follows: (Number of moles of primary acid * (Total number of carboxyl groups per molecule of primary acid)) / (Number of moles of base component * (OH groups that can be produced per molecule of base component)) － This is the ratio of the total number of moles.

[0057] The equivalent ratio of the acid component to the base component (= acid component / base component) may be 0.5 or more and 15 or less, or 1.0 or more and 10 or less. The equivalent ratio of the acid component / base component may be selected from the numerical range described above for the equivalent ratio of the first acid / base component.

[0058] The equivalent ratio of the acid component to the base component is (moles of acid component * (total number of acid groups per molecule of acid component)) / (moles of base component * (OH groups that can be produced per molecule of base component)) － This is the ratio of the total number of moles.

[0059] (Capacitor element) A capacitor element includes an anode, a dielectric layer formed on the surface of the anode, and a cathode portion in contact with a part of the dielectric layer.

[0060] (Anode) The anode may include a valve metal, an alloy containing a valve metal, and a compound containing a valve metal. These materials may be used individually or in combination of two or more. As valve metals, aluminum, tantalum, niobium, and titanium are preferred, for example.

[0061] An anode foil is preferred as the anode body. Preferably, the anode body has a porous portion with pores in at least its surface layer. Other anode bodies include porous sintered bodies or porous molded bodies of particles containing valve metal.

[0062] An anode foil having a porous portion can be obtained, for example, by roughening the surface of a substrate containing a valve-acting metal (such as a foil-shaped or plate-shaped substrate). Surface roughening may be carried out by etching (for example, electrolytic etching or chemical etching).

[0063] (Dielectric layer) The dielectric layer is formed, for example, by anodizing the valve metal on the surface of the anode. Anodizing is carried out, for example, by chemical conversion treatment. The dielectric layer is formed, for example, to cover at least a portion of the surface of the anode.

[0064] The dielectric layer contains, for example, an oxide of the valve metal. For example, when tantalum is used as the valve metal, the dielectric layer contains Ta ２ O ５ It includes. When aluminum is used as the valve metal, the dielectric layer is Al ２ O ３ This includes [the specified element]. However, the dielectric layer is not limited to this; any material that functions as a dielectric is acceptable.

[0065] The dielectric layer is typically formed on the surface of the anode. When the dielectric layer is formed on the surface of a porous portion of the anode, it forms along the inner walls of the pores in the porous portion or the depressions (pits) on the anode surface.

[0066] (Cathode section) The cathode section may consist of a cathode foil and may contain a conductive polymer. The cathode section may also contain a conductive polymer and a cathode extraction layer (such as a cathode foil).

[0067] (Conductive Polymer) The conductive polymer includes, for example, a conjugated polymer and a dopant. The conductive polymer covers at least a portion of the dielectric layer. This embodiment includes cases where the conductive polymer is in contact with at least a portion of the dielectric layer. If the capacitor element includes an anode foil and a cathode foil, the conductive polymer may be interposed between these foils. In this case, the conductive polymer may be impregnated into a separator interposed between the anode foil and the cathode foil. The conductive polymer may be in contact with at least a portion of the cathode foil in addition to at least a portion of the dielectric layer. The conductive polymer may constitute a layer. The conductive polymer is sometimes called a solid electrolyte. The conductive polymer constitutes at least a portion of the cathode body in an electrolytic capacitor. The conductive polymer may further contain additives as needed.

[0068] (Conjugated Polymers) Examples of conjugated polymers include known conjugated polymers used in electrolytic capacitors, such as π-conjugated polymers. Examples of conjugated polymers include polymers with polypyrrole, polythiophene, polyaniline, polyfuran, polyacetylene, polyphenylene, polyphenylenevinylene, polyacene, and polythiophenevinylene as their basic skeleton. The above polymers only need to contain at least one monomer unit that constitutes the basic skeleton. The above polymers also include homopolymers, copolymers of two or more monomers, and derivatives thereof (such as substituted products having substituents). For example, polythiophene also includes poly(3,4-ethylenedioxythiophene) (PEDOT).

[0069] Conjugated polymers may be used individually or in combination of two or more types.

[0070] The weight-average molecular weight (Mw) of the conjugated polymer is not particularly limited, and is, for example, between 1,000 and 1,000,000.

[0071] In this specification, weight-average molecular weight (Mw) or number-average molecular weight (Mn) is a polysaccharide-converted value measured by gel permeation chromatography (GPC). GPC is typically performed using a polyhydroxymethacrylate gel column and an aqueous sodium nitrate mobile phase.

[0072] (Dopants) Examples of dopants include relatively low-molecular-weight anions and high-molecular-weight anions. Examples of anions include sulfate ions, nitrate ions, phosphate ions, borate ions, organic sulfonate ions, and carboxylate ions. Compounds that produce these anions are used as dopants. Examples of dopants that produce sulfonate ions include aromatic sulfonic acid compounds (such as p-toluenesulfonic acid and naphthalenesulfonic acid). Aromatic sulfonic acid compounds may have, for example, at least one selected from the group consisting of a carboxyl group and a hydroxyl group.

[0073] Examples of polymer anions include polyvinyl sulfonic acid, polystyrene sulfonic acid (PSS), polyallyl sulfonic acid, polyacrylic sulfonic acid, polymethacrylate sulfonic acid, poly(2-acrylamido-2-methylpropanesulfonic acid), polyisoprene sulfonic acid, polyester sulfonic acid (such as aromatic polyester sulfonic acid), phenol sulfonic acid novolac resin, and polyacrylic acid. The polymer anion may be a polymer of a single monomer, a copolymer of two or more monomers, or a substituted product having substituents. Among these, polyanions derived from polystyrene sulfonic acid are preferred.

[0074] However, these dopants are merely examples and are not limited to them. A single dopant may be used alone, or two or more may be used in combination.

[0075] The conductive polymer may be formed, for example, by performing at least one of chemical polymerization and / or electropolymerization of a conjugated polymer precursor on a dielectric layer in the presence of a dopant. Alternatively, a conductive polymer (e.g., a layer of conductive polymer) may be formed by contacting a dielectric layer with a solution in which the conductive polymer is dissolved or a dispersion in which the conductive polymer is dispersed. The conductive polymer used in these solutions or dispersions can be obtained by polymerizing a conjugated polymer precursor in the presence of a dopant. Examples of conjugated polymer precursors include raw material monomers for conjugated polymers, oligomers and prepolymers in which multiple molecular chains of raw material monomers are linked together. One type of precursor may be used, or two or more types may be used in combination.

[0076] The Dopant's Mw is not particularly limited and may be between 1,000 and 1,000,000.

[0077] The amount of dopant contained in the conductive polymer may be 10 parts by mass or more and 1000 parts by mass or 20 parts by mass or more and 500 parts by mass per 100 parts by mass of the conjugated polymer.

[0078] (Cathode Extraction Layer) The cathode extraction layer comprises, for example, a first layer covering at least a portion of a conductive polymer. The cathode extraction layer may also comprise a first layer and a second layer covering the first layer. Examples of the first layer include a layer containing conductive particles and a metal foil (cathode foil). Examples of conductive particles include at least one selected from conductive carbon and metal powder. For example, the cathode extraction layer may be composed of a layer containing conductive carbon (such as graphite) as the first layer (also referred to as a carbon layer) and a layer containing metal powder or a metal foil as the second layer. When a metal foil is used as the first layer, the cathode extraction layer may be composed of this metal foil. The cathode extraction layer can be formed by known methods depending on the layer configuration.

[0079] A second layer containing metal powder can be formed, for example, by laminating a composition containing metal powder onto the surface of the first layer. Examples of such a second layer include a metal particle-containing layer (such as a silver particle-containing layer) formed using a composition containing metal particles such as silver particles and a resin (binder resin). As the resin, a thermosetting resin such as an imide resin or epoxy resin may be used, or a thermoplastic resin may be used.

[0080] When using metal foil as the first layer, the type of metal is not particularly limited, but it is preferable to use valve metals such as aluminum, tantalum, or niobium, or alloys containing valve metals. The surface of the metal foil may be roughened as needed. The surface of the metal foil may be coated with a chemical conversion film, or a coating of a metal different from the metal constituting the metal foil (dissimilar metal) or a nonmetal. Examples of dissimilar metals or nonmetals include metals such as titanium and nonmetals such as carbon (conductive carbon, etc.).

[0081] The above-mentioned dissimilar metal or nonmetal (for example, conductive carbon) coating may be used as the first layer, and the above-mentioned metal foil may be used as the second layer.

[0082] (Separator) A separator may be placed between the cathode (cathode foil, etc.) and the anode (anode foil, etc.). The separator is not particularly limited, and for example, nonwoven fabrics containing fibers of cellulose, polyethylene terephthalate, vinylon, or polyamide (e.g., aliphatic polyamide, aromatic polyamide such as aramid) may be used.

[0083] If the capacitor element includes a separator, the conductive polymer may be impregnated into the separator. In this case, the separator may be impregnated with an electrolyte. The conductive polymer is interposed between the anode (such as an anode foil) and the cathode (such as a cathode foil), and may be in contact with at least a portion of the dielectric layer and at least a portion of the cathode.

[0084] (Bottomed case) The bottomed case has an opening. The bottomed case may be cylindrical, for example.

[0085] The bottomed case is made of metal, resin, or the like. Examples of metal materials include aluminum, copper, iron, and other metals or their alloys (including stainless steel and brass). Examples of resin materials include thermoplastic resins or compositions containing them.

[0086] (Sealing body) The sealing body that seals the opening of the bottomed case contains an elastic polymer. Examples of elastic polymers include butyl rubber (IIR), isoprene rubber, nitrile rubber, silicone rubber, fluororubber, ethylene propylene rubber, ethylene propylene diene rubber, chloroprene rubber, and chlorosulfonated polyethylene rubber (such as Hypalon rubber). The sealing body may contain one type of elastic polymer, or a combination of two or more types.

[0087] When the encapsulant contains butyl rubber, if reflow processing is performed under relatively severe conditions, the internal pressure of the electrolytic capacitor increases, causing the encapsulant to swell and reducing its mountability on the substrate. In this disclosure, even in such cases, the increase in the internal pressure of the electrolytic capacitor can be suppressed, allowing the electrolytic capacitor to be stably mounted on the substrate.

[0088] The encapsulant may contain known additives such as fillers. Examples of fillers include carbon black and silica.

[0089] (Other) Electrolytic capacitors may be wound type, chip type, or multilayer type. Electrolytic capacitors have at least one capacitor element. Electrolytic capacitors may have multiple capacitor elements. For example, an electrolytic capacitor may have a multilayer structure of two or more capacitor elements, or it may have two or more wound type capacitor elements. The configuration or number of capacitor elements may be selected depending on the type or application of the electrolytic capacitor.

[0090] In a capacitor element, one end of the cathode lead is electrically connected to the cathode lead-out layer. One end of the anode lead is electrically connected to the anode body. The other end of the anode lead and the other end of the cathode lead are led out from the bottomed case. The other ends of each lead exposed from the bottomed case are used for soldering to the substrate on which the electrolytic capacitor is to be mounted. Lead wires or lead frames may be used for each lead.

[0091] The electrolytic capacitors of this disclosure suppress the rise in internal pressure even under relatively severe reflow conditions, and are stably mounted on the substrate. Examples of such reflow conditions include high-temperature reflow and long-duration reflow. The electrolytic capacitors of this disclosure are suitable for applications requiring reflow at a temperature of 200°C or higher for 80 seconds or more (preferably applications requiring reflow at a temperature of 240°C or higher for 20 seconds or more, 35 seconds or more, or 40 seconds or more). Furthermore, the electrolytic capacitors of this disclosure are also suitable for applications requiring multi-stage reflow. Examples of such applications include those requiring at least two stages of reflow, such as a first reflow with a peak temperature of 200°C or higher and less than 240°C, and a second reflow with a peak temperature of 240°C or higher and 300°C or lower. In the first reflow, for example, reflow is performed at a temperature of 200°C or higher for 80 seconds or more, preferably 90 seconds or more. In the second reflow process, the reflow time is preferably 5 seconds or more, more preferably 20 seconds or more, and even more preferably 35 seconds or 40 seconds or more. For example, in applications where electronic components are mounted on a substrate at high density, the number of electrolytic capacitors mounted tends to be large. In this case, the mounting defect rate tends to increase, so it is necessary to ensure that each electrolytic capacitor is mounted on the substrate more reliably. In this case, to ensure more reliable mounting, the reflow process may be performed at a higher temperature than usual, the reflow process time may be extended, or the reflow process may be performed in multiple stages. With the electrolytic capacitors of this disclosure, even when reflow processing is performed under such relatively severe conditions, the mounting defect rate on the substrate is low, and stable mounting is possible. For example, even when reflow processing (such as the second reflow process) is performed at a temperature of 240°C or higher for a long period of time such as 20 seconds, 35 seconds, or 40 seconds, the electrolytic capacitors can be mounted on the substrate stably. The reflow process time is usually 5 minutes or less (or 4 minutes or less).

[0092] Prior to reflow processing at a temperature of 200°C or higher, a preheating process at a temperature of 160°C or higher but less than 200°C may be performed. The total time for preheating and reflow processing may be 7 minutes or less.

[0093] The electrolyte of this disclosure can be used in electrolytic capacitors such as hybrid electrolytic capacitors. The electrolytic capacitor of this disclosure has high mounting stability by suppressing swelling of the encapsulant even under relatively severe reflow conditions. Therefore, the electrolytic capacitor of this disclosure is suitable for applications that require high-temperature reflow processing or relatively long reflow processing (for example, applications where it is mounted at high density on a substrate). However, the applications of electrolytic capacitors are not limited to these.

[0094] Figure 1 is a schematic cross-sectional view of an electrolytic capacitor according to one embodiment of the present disclosure, and Figure 2 is a schematic diagram showing a part of the capacitor element relating to the electrolytic capacitor unfolded. However, the electrolytic capacitor of the present disclosure is not limited to the following embodiments. Furthermore, the components of the following embodiments may be arbitrarily combined with at least one of the above technologies (1) to (7) relating to the electrolytic capacitor of the present disclosure, or at least one of the above technologies (1) to (7) and the components described above.

[0095] An electrolytic capacitor comprises, for example, a capacitor element 10, a bottomed case 101, a sealing member 102 that closes the opening of the bottomed case 101, a base plate 103 that covers the sealing member 102, lead wires 104A, 104B, and lead tabs 105A, 105B. The bottomed case 101 houses the capacitor element 10 and an electrolyte (not shown). The area near the opening end of the bottomed case 101 is tapered inward, and the opening end is curled so as to be crimped to the sealing member 102. The lead wires 104A and 104B are led out from the sealing member 102 and pass through the base plate 103. The lead tabs 105A and 105B connect the lead wires 104A and 104B to the electrodes of the capacitor element 10, respectively.

[0096] The capacitor element 10 is, for example, a wound body as shown in Figure 2. The wound body comprises an anode foil 11 connected to a lead tab 105A, a cathode foil 12 connected to a lead tab 105B, and a separator 13. The anode foil 11 and the cathode foil 12 are wound around the separator 13. The outermost circumference of the wound body is secured by a winding stopper tape 14. Note that Figure 2 shows the state in which a portion of the wound body is unfolded before securing the outermost circumference.

[0097] In the capacitor element 10, a dielectric layer (not shown) is formed on at least a portion of the surface of the anode foil 11. A separator 13 and a conductive polymer (not shown) are interposed between the anode foil 11 and the cathode foil 12. The conductive polymer is in contact with at least a portion of the dielectric layer. The conductive polymer is also in contact with at least a portion of the cathode foil 12. The conductive polymer and the separator are impregnated with an electrolyte.

[0098] [Examples] The present invention will be described below in detail based on examples and comparative examples, but the present invention is not limited to the following examples.

[0099] Examples 1-12 and Comparative Examples 1-6: Wind-wound electrolytic capacitors (rated voltage 25V and rated capacitance 330μF) were fabricated and evaluated using the following procedure.

[0100] (Preparation of the anode) A 100 μm thick aluminum foil was etched to roughen its surface. Then, a dielectric layer was formed on the surface of the aluminum foil by chemical conversion treatment. The chemical conversion treatment was performed by immersing the aluminum foil in an ammonium adipate solution and applying a voltage to it. After that, the aluminum foil was cut to a size of 8 mm x 120 mm to prepare the anode.

[0101] (Preparation of the cathode) A 50 μm thick aluminum foil was etched to roughen its surface. Then, the aluminum foil was cut to a size of 8 mm x 120 mm to prepare the cathode.

[0102] (Fabrication of the wound body) Anode lead tabs and cathode lead tabs were connected to the anode and cathode bodies, and the anode and cathode bodies were wound together with paper separators, winding the lead tabs as they were wound. Anode lead wires and cathode lead wires were connected to the ends of each lead tab protruding from the wound body. Then, the fabricated wound body was subjected to another chemical conversion treatment to form a dielectric layer on the cut end of the anode body. Next, the ends of the outer surface of the wound body were fixed with winding tape to fabricate the wound body.

[0103] (Preparation of polymer dispersion containing conductive polymer) 3,4-ethylenedioxythiophene and the polymer dopant poly(4-styrenesulfonic acid) (PSS, Mw 100,000) were dissolved in deionized water to prepare a mixed solution. While stirring the mixed solution, an oxidizing agent (ferrous sulfate and ammonium persulfate) dissolved in deionized water was added to carry out the polymerization reaction. After the reaction, the resulting reaction solution was dialyzed to remove unreacted monomers and excess oxidizing agent, and a polymer dispersion containing PSS-doped poly(3,4-ethylenedioxythiophene) (PEDOT / PSS) as the conductive polymer was obtained. The Mw of the polymer dopant is the value measured under the conditions described above.

[0104] (Coating of the dielectric layer with conductive polymer) The wound body was immersed in a polymer dispersion contained in a predetermined container for 5 minutes in a reduced-pressure atmosphere (40 kPa), and then the wound body was removed from the polymer dispersion. Next, the wound body impregnated with the polymer dispersion was dried in a drying oven at 150°C for 20 minutes, and at least a portion of the dielectric layer was coated with a conductive polymer. In this way, a capacitor element was formed.

[0105] (Impregnation of electrolyte) A mixture obtained by mixing GBL, SL, and PEG (number average molecular weight: 300) in a volume ratio of GBL:SL:PEG = 1:1:1 was used as the solvent for the electrolyte. The electrolyte was prepared by dissolving the primary acid:phthalic acid (acid component) and the base component (TEA) in this mixture. The equivalent ratio of phthalic acid to the base component in the electrolyte (=phthalic acid / base component) was set to 2.0. By adjusting the concentrations of the acid and base components, the total mass of the acid and base components per unit volume inside the initial electrolytic capacitor, as measured by the procedure described above, was changed. The water content of the electrolyte, as measured by the procedure described above, was 0.010 mg / mm³ per unit volume inside the initial electrolytic capacitor. ３ The amount of water in the electrolyte was adjusted to achieve the desired result. The concentration of the acid component in the electrolyte of the example was 3% by mass or more and 14% by mass or less.

[0106] (Assembly of electrolytic capacitors) The capacitor elements were immersed in the electrolyte and placed in a reduced pressure atmosphere (40 kPa) for 5 minutes to allow the electrolyte to penetrate the capacitor elements.

[0107] A capacitor element impregnated with electrolyte was housed in a bottomed case, with the lead wires positioned on the opening side of the bottomed case. A seal containing an IIR, formed to allow the lead wires to pass through, was placed above the capacitor element. Then, a drawing process was performed near the opening end of the bottomed case, and the opening end was further curled to create a tight seal with the seal. In this way, the capacitor element and electrolyte were sealed inside the bottomed case. By placing a base plate on the curled portion, an electrolytic capacitor as shown in Figure 1 was completed. A total of 20 electrolytic capacitors were manufactured for each example. The manufactured electrolytic capacitors were subjected to an aging process at 130°C for 2 hours while applying the rated voltage.

[0108] [Evaluation] The length from the bottom of the electrolytic capacitor case to the top of the sealant (initial length L0) was measured with calipers immediately after the aging process.

[0109] Next, the electrolytic capacitor was subjected to a first reflow process at 200°C for 90 seconds, followed by a second reflow process at a temperature between 240°C and 260°C, with a peak temperature of 260°C, for 40 seconds. After these reflow processes, the length (L1) after reflow was measured with calipers in the same manner as described above.

[0110] Then, for each electrolytic capacitor, the bulge of the sealing material (unit: mm) was determined from L1 to L0, and the average value of 20 values ​​was calculated. The total mass of acidic and basic components per unit volume inside the electrolytic capacitor (unit: mg / mm) was also calculated. ３ The average swelling of the sealant (unit: mm) was plotted against the given values. The results are shown in Figure 3. In Figure 3, C1-C6 are Comparative Examples 1-6, and E1-E12 are Examples 1-12.

[0111] As shown in Figure 3, the total mass of acidic and basic components per unit volume inside the electrolytic capacitor is 0.008 mg / mm³. ３ When the value was less than 0.008 mg / mm³, the bulging of the sealant was significant (C1-C6). In contrast, when the total mass of acidic and basic components per unit volume inside the electrolytic capacitor was 0.008 mg / mm³, ３ 0.050mg / mm or more ３ In the following cases, the bulging of the sealant is very small (E1-E12), at 0.008 mg / mm³. ３ The trend was significantly different from the case where the value was less than [amount].

[0112] Figure 3 shows that the mass of water per unit volume inside the electrolytic capacitor is 0.010 mg / mm³. ３ This is the case. This mass is 0.003 mg / mm³. ３ When the value is less than the threshold, unlike in Figure 3, no critical point is observed where the swelling tendency of the sealant differs even when the total mass of acidic and basic components per unit volume inside the electrolytic capacitor changes.

[0113] Although the present invention has been described in relation to preferred embodiments at present, such disclosure should not be interpreted restrictively. Various modifications and alterations will undoubtedly become apparent to those skilled in the art in the field to which the invention pertains by reading the above disclosure. Accordingly, the appended claims should be interpreted as encompassing all modifications and alterations without departing from the true spirit and scope of the invention.

[0114] 100: Electrolytic capacitor 101: Bottomed case 102: Sealing material 103: Base plate 104A, 104B: Lead wires 105A, 105B: Lead tabs 10: Capacitor element 11: Anode foil 12: Cathode foil 13: Separator 14: Winding tape

Claims

1. An electrolytic capacitor comprising a bottomed case having an opening, a capacitor element and an electrolyte housed in the bottomed case, and a sealant containing an elastic polymer that seals the opening, wherein the electrolyte contains an organic solvent, an acid component, a basic component, and water, the organic solvent mainly comprises a first solvent having a boiling point of 200°C or more and 300°C or less, the acid component comprises a carboxylic acid compound, the basic component comprises at least one selected from the group consisting of organic bases and ammonia, and the mass of water per unit volume inside the electrolytic capacitor is 0.003 mg / mm³. ３ The above is true, and the total mass of the acidic component and the base component per unit volume inside the electrolytic capacitor is 0.008 mg / mm³. ３ 0.050mg / mm or more ３ The following are electrolytic capacitors.

2. The electrolytic capacitor according to claim 1, wherein the first solvent comprises at least one selected from the group consisting of lactone compounds and sulfone compounds.

3. The mass of water per unit volume inside the electrolytic capacitor is 0.003 mg / mm³. ３ 0.025mg / mm or more ３ The electrolytic capacitor according to claim 1 or 2, which is as follows:

4. The electrolytic capacitor according to claim 1 or 2, wherein the elastic polymer includes butyl rubber.

5. An electrolytic capacitor according to claim 1 or 2, used in applications requiring reflow processing at a temperature of 200°C or higher for 80 seconds or more.

6. The electrolytic capacitor according to claim 5, which is used in applications requiring at least two reflow processes, a first reflow process having a peak temperature of 200°C or more and less than 240°C, and a second reflow process having a peak temperature of 240°C or more and 300°C or less.

Images