JP2022040698A - Solid electrolytic capacitor and method for manufacturing the same - Google Patents

Abstract

To provide a solid electrolytic capacitor having a configuration where leakage current can be reduced even when heat treatment such as reflow is subjected.SOLUTION: A solid electrolytic capacitor 1 has an anode foil 2a on which an oxide film is formed, a cathode foil 2c, and a separator 2d arranged between the anode foil and the cathode foil, and also includes a solid electrolyte 20 formed by particulate conductive polymer compound 2e and a liquid composition 30 introduced to surround the solid electrolyte. The liquid composition contains an acid component and a basic component, and contains the basic components in an amount equal to or less than the number of moles of the acid component, the acid component containing hypophosphorous acid.SELECTED DRAWING: Figure 1

Description

The present invention relates to a solid electrolytic capacitor and a method for manufacturing the same.

A solid electrolytic capacitor using a conductive polymer compound has excellent temperature stability and features such as a small equivalent series resistance (abbreviated as ESR).

Conventionally, a solid electrolytic capacitor having a structure using γ-butyrolactone and mono (ethyldimethylamine) phthalate as an electrolytic solution has been proposed (Patent Document 1: International Publication No. 2016/088300). Further, a solid electrolytic capacitor having a structure using γ-butyrolactone, pyrrolitic acid, maleic acid, hypophosphoric acid, and 1-ethyl-3methylimidazolium as the electrolytic solution has been proposed (Patent Document 2: Special Patent Document 2: Open 2012-109635A, Patent Document 3: Japanese Patent Application Laid-Open No. 2006-114540). Then, a solid electrolytic capacitor having a structure using an amine salt of a carboxylic acid as an electrolytic solution has been proposed (Patent Document 4: International Publication No. 2011/099261).

International Publication No. 2016/088300 Japanese Unexamined Patent Publication No. 2012-109635 Japanese Unexamined Patent Publication No. 2006-114540 International Publication No. 2011/099261

Solid electrolytic capacitors are generally used after being heat-treated such as reflow at the mounting stage. Recently, unstable individuals have been found in which leakage current increases after heat treatment such as reflow, and the demand from the market is becoming stricter. However, with the prior art described in Patent Documents 1 to 4, it is extremely difficult to manufacture only a product having a small leakage current even when heat treatment such as reflow is performed. Even if the above-mentioned unstable individuals are unavoidably selected in an attempt to meet the above-mentioned requirements, the above-mentioned unstable individuals cannot be reliably removed, and the yield of low-leakage current products is greatly reduced, resulting in a sharp rise in manufacturing costs and unstable supply. There is a risk of becoming.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a solid electrolytic capacitor having a configuration capable of reducing a leakage current even when heat treatment such as reflow is performed.

As an embodiment, the problem is solved by a solution means as disclosed below.

The solid electrolytic capacitor of the present invention has an anode foil on which an oxide film is formed, a cathode foil, and a separator disposed between the anode foil and the cathode foil, and is a fine-grained conductive polymer. It comprises a solid electrolyte formed by the compound and a liquid composition introduced so as to surround the solid electrolyte. The liquid composition contains an acid component and a base component, and the base component is contained in an amount equal to or less than the number of moles of the acid component. The liquid composition contains an acid component and a base component, and the base is contained. One or more of the configurations containing the component in an amount of less than 0.06 [mol / kg], or the structure in which the liquid composition contains an acid component and the liquid composition does not contain a base component. Is. Moreover, the acid component is characterized by containing hypochlorous acid.
Further, the method for manufacturing a solid electrolytic capacitor of the present invention has an anode foil on which an oxide film is formed, a cathode foil, and a separator disposed between the anode foil and the cathode foil, and is in the form of fine particles. A method for producing a solid electrolytic capacitor including a solid electrolyte formed of the conductive polymer compound of the above and a liquid composition introduced so as to surround the solid electrolyte. The liquid composition is the following as an acid component. It is characterized in that the leakage current is reduced even after reflow by containing phosphite.

According to this configuration, the leakage current can be reduced even when heat treatment such as reflow is performed. In addition to the above-mentioned effects, the configuration in which the acid component is composed only of hypochlorous acid can make the initial value of the leakage current particularly small. The structure in which the liquid composition contains the base component in an amount equal to or less than the number of moles of the acid component can make the initial value of the capacitance particularly large in addition to the above-mentioned effects. A structure in which the liquid composition contains a base component in an amount of less than 0.06 [mol / kg] or a structure in which the liquid composition does not contain a base component reflows in addition to the above-mentioned effects. The change in ESR due to heat treatment such as is particularly small.

The liquid composition preferably contains a liquid polyol compound as a solvent. This results in a liquid composition that is highly fluid and contains a large amount of hydroxyl groups, further improves the ability to repair defects in the anodic oxide film, and has the effect of preventing an increase in leakage current even when heat treatment such as reflow is performed. It will be higher. The liquid composition preferably contains a liquid polyol compound as a main solvent. As an example, a configuration in which the liquid composition contains water further enhances the ability to repair defects in the anodic oxide film. In the liquid composition, the proportion of water is preferably 10 [wt%] or less, more preferably 5 [wt%] or less, and even more preferably 2 [wt%] or less. As a result, the increase in the internal pressure of the solid electrolytic capacitor at high temperature is suppressed, so that the product can be produced with a smaller leakage current and no swelling of the case even when heat treatment such as reflow is performed. The liquid composition preferably has a hypochlorous acid ratio of 0.95 [wt%] or less. As a result, deterioration of the conductive polymer compound is suppressed, and it is possible to prevent the capacitance from being significantly reduced and the ESR from being significantly increased when heat treatment such as reflow is performed. The inorganic acid among the acid components contained in the liquid composition may be hypochlorous acid only.

According to the solid electrolytic capacitor of the present invention, the leakage current can be reduced even when heat treatment such as reflow is performed. Further, according to the method for manufacturing a solid electrolytic capacitor of the present invention, it is possible to eliminate an unstable individual in which a leakage current increases after a heat treatment such as reflow, and a low leakage current product can be stably supplied.

FIG. 1 is a diagram schematically showing a main part of a capacitor element according to an embodiment of the present invention. 2A is a schematic partial cross-sectional view showing the structure of the solid electrolytic capacitor having the main part shown in FIG. 1, and FIG. 2B is a schematic view of the solid electrolytic capacitor having the main part shown in FIG. 1 as viewed from the case opening side. Is. FIG. 3 is a diagram showing a state in which an anode foil to which a lead terminal is bonded, a cathode foil to which a lead terminal is bonded, and a separator are overlapped and wound in the present embodiment. FIG. 4 is a flowchart showing a manufacturing procedure of the solid electrolytic capacitor of the present embodiment.

First, the structure and the like of the capacitor element 2 according to the embodiment of the present invention will be described below. In all the drawings for explaining the embodiment, the members having the same function may be designated by the same reference numerals, and the repeated description thereof may be omitted.

FIG. 1 is a diagram schematically showing a main part of a capacitor element 2 in the solid electrolytic capacitor 1 of the present embodiment. The anode foil 2a and the cathode foil 2c are formed of a valve metal such as aluminum, tantalum, and niobium. The surface of the anode foil 2a is roughened by an etching treatment, and then an oxide film 2b is formed by a chemical conversion treatment. Further, the surface of the cathode foil 2c is roughened by an etching treatment in the same manner as the anode foil 2a, and then a natural oxide film 2h is formed. As an example, the anode foil 2a and the cathode foil 2c are made of aluminum. A separator 2d is arranged between the anode foil 2a and the cathode foil 2c. The separator 2d is, for example, a cellulose fiber that is chemically compatible with a conductive polymer or a water-soluble polymer, or nylon, polypropylene (PP), polyethylene (PE), or polyethylene terephthalate (PET) having excellent heat resistance. ), Polyphenylene sulfide (PPS) and other synthetic resins are applied. As an example, heat resistant cellulose paper is applied to the separator 2d. Then, the solid electrolyte 20 and the liquid composition 30 are introduced into the gap between the anode foil 2a and the cathode foil 2c so that the liquid composition 30 surrounds the solid electrolyte 20. On the anode side, the solid electrolyte 20 is formed so as to be in contact with the oxide film 2b of the anode foil 2a. As an example, the solid electrolyte 20 is formed in a columnar shape, a mesh shape, a layered shape, or the like. The solid electrolyte 20 contains the conductive polymer compound 2e in the form of fine particles having a size on the order of nanometers, and the liquid composition 30 is introduced so as to surround the solid electrolyte 20.

The conductive polymer compound 2e is, for example, poly (3,4-ethylenedioxythiophene) (PEDOT), poly (4-styrene sulfonic acid) -doped poly (3,4-ethylenedioxythiophene) (PEDOT). / PSS), tetracyanoquinodimethane (TCNQ), polypyrrole (PPy), polyaniline (PANI), polythiophene (PT), or other known conductive polymer compounds. According to this, it becomes possible to increase the withstand voltage, and as an example, the withstand voltage can be increased to 100 [V]. Further, the conductive polymer compound 2e preferably contains a conductive polymer compound having at least one of polystyrene sulfonic acid, toluene sulfonic acid, alkylbenzene sulfonic acid, and naphthalene sulfonic acid as a dopant. This stabilizes the conductivity. The average particle size of the conductive polymer compound 2e is, for example, 1 [nm] or more and 300 [nm] or less. When the average particle size of the conductive polymer compound 2e is less than 1 [nm], it may be difficult to produce the conductive polymer compound in the form of fine particles. On the other hand, when the average particle size of the conductive polymer compound 2e is larger than 300 [nm], it becomes difficult to introduce the conductive polymer compound 2e into the etching pits (recesses) on the surface of the anode foil 2a. There is. From such a viewpoint, the average particle size of the conductive polymer compound 2e is particularly preferably 2 [nm] or more, and more preferably 3 [nm] or more. Further, the average particle size of the conductive polymer compound 2e is particularly preferably 200 [nm] or less, and more preferably 100 [nm] or less.

FIG. 2A is an example of a schematic partial cross-sectional view showing the structure of the solid electrolytic capacitor 1 of the present embodiment. The solid electrolytic capacitor 1 is a capacitor element 2 in which a solid electrolyte 20 containing a finely divided conductive polymer compound 2e is formed, a lead terminal 5 and a lead terminal 6, and a sealing body in which through holes are formed in two places. 3 and a bottomed metal case 4 for accommodating the capacitor element 2 and a liquid composition 30 introduced so as to surround the solid electrolyte 20 are provided, and the opening side of the case 4 is sealed by the sealing body 3. It has been stopped. In the examples of FIGS. 2A and 2B, a horizontal diaphragm portion is formed on the side surface of the case 4 on the opening side, and the opening end portion is bent. The capacitor element 2 is not arranged on the opening side of the case 4, and a part of the first surface of the sealing body 3 and the extraction terminal of the lead terminal 5 (6) are exposed. The sealing body 3 is supported and fixed by the lateral throttle portion and the opening end portion of the case 4. Each of the lead terminal 5 and the lead terminal 6 has a round bar portion fitted in a through hole of the sealing body 3, and is supported and fixed by the sealing body 3. Here, in order to make it easier to explain the positional relationship of each part of the solid electrolytic capacitor 1, the directions are indicated by the arrows X, Y, and Z in the figure. When the solid electrolytic capacitor 1 is actually used, it is not limited to these directions, and there is no problem even if it is used in any direction.

The case 4 has a bottomed cylinder shape and is made of a metal such as aluminum. The sealing body 3 has high airtightness in order to prevent the infiltration of water and the scattering of the oxide film repairing substance, and has a substantially cylindrical shape matching the inner shape of the case 4. The sealing body 3 is made of an insulating rubber composition as an example. As an example, isobutylene / isoprene rubber, butyl rubber, ethylene propylene rubber, fluororubber, or other known elastomer is applied to the sealing body 3. The lead terminal 5 and the lead terminal 6 are each made of tin-plated copper-coated steel wire (CP wire) as an example. This facilitates soldering to an external substrate or the like. The extraction terminal may be a round pin or a square pin. The lead terminal 5 is bonded to the anode foil 2a, and the lead terminal 6 is bonded to the cathode foil 2c. The length of the lead terminal 5f of the lead terminal 5 is longer than the length of the lead terminal 6f of the lead terminal 6, which enhances the visibility of the polarity. As an example, the lead terminal 5 and the lead terminal 6 can have the same shape and the same structure except for the difference in the length of the drawer terminal. The flat portion, the first step portion, and the round bar portion of the lead terminal 5 and the lead terminal 6 are made of aluminum as an example, and are formed by press working.

Subsequently, a method for manufacturing the solid electrolytic capacitor 1 according to the present embodiment will be described below.

FIG. 4 is a flowchart showing a manufacturing procedure of the solid electrolytic capacitor 1. As an example, the solid electrolytic capacitor 1 is manufactured in the order of joining step S1, element forming step S2, first introduction step S3, second introduction step S4, fitting step S5, sealing step S6, and aging step S7. In addition to the above manufacturing procedure, the order of the second introduction step S4 and the fitting step S5 can be exchanged, and the sealing step S6 can be provided after the aging step S7. After the aging step S7, the fitting step S5 and the sealing step S6 can be provided.

In the joining step S1, as an example, the flat portion of the lead terminal 5 and the anode foil 2a are overlapped with each other, and a plurality of joining portions are formed at predetermined intervals by penetrating the predetermined portions with a needle or the like, and the formed burr portions are pressed. It is processed and joined to the anode foil 2a to enable electrical connection. The same applies to the cathode foil 2c. If a plurality of joint points are formed, the electrical connection state is stable. Therefore, there are cases where there are two connection points, three points, or four or more points.

As an example, in the element forming step S2, as shown in FIG. 3, a separator 2d is sandwiched between the anode foil 2a and the cathode foil 2c to separate the electrode foils, and the anode foil 2a and the cathode foil 2c are separated from each other. It is wound through the separator 2d to form a cylindrical shape. Then, a tape, a film, or the like is attached to the outer peripheral portion of the cylindrical shape to maintain the wound state (not shown). Next, in the chemical conversion treatment in the element formation step S2, as an example, a chemical conversion liquid tank containing the chemical conversion liquid is prepared, then the element is immersed in the chemical conversion liquid in the chemical conversion liquid tank, and the drawer terminal 5f and the chemical conversion liquid are immersed. A predetermined voltage is applied between and for a predetermined time. As an example, a voltage of 100 [V] is applied for 5 [minutes] to repair the oxide film defect existing at the end of the anode foil 2a and the oxide film defect that may exist on the surface (not shown). .. Then, the element is pulled up from the chemical conversion liquid tank and dried to be in a chemical conversion-treated state. Examples of the chemical conversion solution include aqueous solutions of ammonium adipate, ammonium borate, ammonium phosphate, ammonium glutarate, ammonium azelaite, ammonium tartrate, ammonium sebacate, ammonium pimelic acid, ammonium suberate and the like.

In the first introduction step S3, the dispersion liquid containing the fine particle conductive polymer compound 2e is introduced into the element in the chemical conversion treatment state and dried to form the solid electrolyte 20. The medium of the dispersion is either water or a water-soluble liquid, or both. In the first introduction step S3, as an example, a dispersion liquid tank containing the dispersion liquid is prepared. Next, the element in the chemical conversion treatment state is immersed in the dispersion liquid. Then, it is pulled up from the dispersion liquid tank, dried, and brought into the state of being first introduced. The number of drying times is one or two or more, and the first introduction step S3 may be repeated a plurality of times. The concentration of the conductive polymer compound 2e in the dispersion is, for example, 0.1 [vol%] or more and 10 [vol%] or less. By setting the concentration of the conductive polymer compound 2e to 0.1 [vol%] or more, the desired capacitor characteristics can be exhibited. By setting the concentration of the conductive polymer compound 2e to 10 [vol%] or less, the conductive polymer compound 2e is uniformly dispersed in the dispersion liquid. The concentration of the conductive polymer compound 2e is preferably 7 [vol%] or less, and the concentration of the conductive polymer compound 2e is more preferably 3 [vol%] or less. In the second introduction step S4, the liquid composition 30 capable of repairing the oxide film 2b of the anode foil 2a is introduced. As an example, a solution tank containing the liquid composition 30 is prepared. Next, the device in which the solid electrolyte 20 is formed is immersed in the liquid composition 30. Then, the element is pulled up from the solution tank to make the capacitor element 2 in the state where the liquid composition 30 has been introduced.

In the fitting step S5, as an example, the case 4 and the sealing body 3 are prepared, and then the capacitor element 2 in the state where the liquid composition 30 has been introduced is housed in the case 4, and the lead terminal 5 is round. The rod portion and the round rod portion of the lead terminal 6 are fitted into the two through holes of the sealing body 3, respectively. In the sealing step S6, as an example, the opening side of the case 4 is caulked to form a horizontal drawing portion on the side surface of the case 4 on the opening side, and the opening end portion is bent. By this caulking process, as shown in FIG. 2, the sealing body 3 is supported and fixed by the lateral drawing portion and the opening end portion of the case 4. That is, the sealing body 3 and the capacitor element 2 are housed in the bottomed case 4, and the sealing body 3 is supported and fixed by the molding process on the opening side of the case 4.

In the aging step S7, after the opening side of the case 4 is sealed by the sealing body 3, the lead terminal 5, and the lead terminal 6, the outer sleeve is attached to the case 4, the outer sleeve is heat-processed, and the aging process is performed. .. In the aging treatment, a voltage is applied for a predetermined time under high temperature conditions, and the oxide film repairing action of the liquid composition 30 is used to use the metal base metal portion such as the joint portion and the cross section of the anode foil 2a and the weak portion of the oxide film 2b. To regenerate. As a result, the leakage current is suppressed and stabilized. The aging process also has a debugging effect such as removal of unexpected initial defects.

Subsequently, each Example and each Comparative Example will be described below.

The manufacturing method is as described above, and the winding type is formed by winding the anode foil 2a to which the lead terminal 5 is bonded and the cathode foil 2c to which the lead terminal 6 is bonded with the separator 2d interposed therebetween. The capacitor element 2 of the above was formed. Next, the capacitor element 2 is immersed in an aqueous solution of ammonium adipate, and a voltage of 100 [V] is applied between the lead terminal 5 on the anode foil 2a side and the chemical conversion solution by 5 [minutes] to end the anode foil 2a. The oxide film defect portion existing in the portion and the oxide film defect portion on the surface of the anode foil 2a were repaired, and then dried at a temperature of 105 [° C.] for 5 [minutes]. Next, a dispersion liquid in which poly (3,4-ethylenedioxythiophene) (PEDOT / PSS) doped with poly (4-styrene sulfonic acid) was dispersed in water as a particulate conductive polymer compound 2e was used. Then, a solid electrolyte 20 containing the fine-grained conductive polymer compound 2e was formed in the gap between the anode foil 2a and the cathode foil 2c in the condenser element 2. Then, in each example, the liquid composition 30 was introduced so as to surround the solid electrolyte 20 in the gap between the anode foil 2a and the cathode foil 2c. On the other hand, in each Comparative Example, a predetermined liquid was introduced so as to surround the solid electrolyte 20 in the gap between the anode foil 2a and the cathode foil 2c. Here, the solid electrolyte 20 is configured to contain 2 [wt%] or more of the conductive polymer compound 2e. Further, the liquid composition 30 is configured to contain water in an amount of 0.5 [wt%] or more and 2 [wt%] or less. Then, using the sealing body 3 made of isobutylene and isoprene rubber, the round bar portions of the lead terminal 5 and the lead terminal 6 of the capacitor element 2 are fitted into the through holes of the sealing body 3, and the capacitor element 2 is inserted. It was inserted into the case 4, and then caulked in the vicinity of the open end of the case 4 to support and fix the sealing body 3. Then, an aging process was performed by applying a predetermined voltage of 60 [minutes] at a temperature of about 85 [° C.] to produce a solid electrolytic capacitor 1 having a rated voltage of 25 [WV]. The number of samples is 20 each.

Subsequently, each preparation example of the liquid composition used in Examples 1 to 23 and each preparation example of the predetermined liquid used in Comparative Examples 1 to 3 will be described below.

[Preparation Example A1]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.05 [wt%]. Contains no acid components other than hypochlorous acid. Moreover, the base component is not blended. The main solvent is diethylene glycol.

[Preparation Example A2]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.15 [wt%]. Other than that, it is the same as Preparation Example A1.

[Preparation Example A3]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.4 [wt%]. Other than that, it is the same as Preparation Example A1.

[Preparation Example A4]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.8 [wt%]. Other than that, it is the same as Preparation Example A1.

[Preparation Example A5]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.95 [wt%]. Other than that, it is the same as Preparation Example A1.

[Preparation Example B1]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.05 [wt%]. Contains no acid components other than hypochlorous acid. Moreover, the base component is not blended. The main solvent is polyethylene glycol (PEG200) having an average molecular weight of 200.

[Preparation Example B2]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.15 [wt%]. Other than that, it is the same as Preparation Example B1.

[Preparation Example B3]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.4 [wt%]. Other than that, it is the same as Preparation Example B1.

[Preparation Example B4]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.8 [wt%]. Other than that, it is the same as Preparation Example B1.

[Preparation Example C1]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.4 [wt%]. Contains no acid components other than hypochlorous acid. Moreover, the base component is not blended. The main solvent is a mixture of diethylene glycol and PEG200 at a weight ratio of 2: 1.

[Preparation Example C2]
The main solvent is a mixture of diethylene glycol and PEG200 at a weight ratio of 1: 1. Other than that, it is the same as Preparation Example C1.

[Preparation Example C3]
The main solvent is a mixture of diethylene glycol and PEG200 at a weight ratio of 1: 2. Other than that, it is the same as Preparation Example C1.

[Preparation Example C4]
The main solvent is a mixture of diethylene glycol and glycerin in a weight ratio of 1: 1. Other than that, it is the same as Preparation Example C1.

[Preparation Example D]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.05 [wt%]. Contains no acid components other than hypochlorous acid. Further, as a base component, ammonia was blended so as to have a molar ratio of the base component 1 to the acid component 1. The amount of the base component per unit mass in the liquid composition is 0.008 [mol / kg]. The main solvent is diethylene glycol.

[Preparation Example E]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.15 [wt%]. Contains no acid components other than hypochlorous acid. Further, as a base component, ammonia was blended so as to have a molar ratio of the base component 1 to the acid component 1. The amount of the base component per unit mass in the liquid composition is 0.02 [mol / kg]. The main solvent is diethylene glycol.

[Preparation Example F]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.4 [wt%]. Contains no acid components other than hypochlorous acid. Further, as a base component, ammonia was blended so as to have a molar ratio of the base component 1 to the acid component 1. The amount of the base component per unit mass in the liquid composition is 0.06 [mol / kg]. The main solvent is diethylene glycol.

[Preparation Example G1]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.8 [wt%]. Contains no acid components other than hypochlorous acid. Further, as a base component, ammonia was blended so as to have a molar ratio of the base component 1 to the acid component 1. The amount of the base component per unit mass in the liquid composition is 0.1 [mol / kg]. The main solvent is diethylene glycol.

[Preparation Example G2]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.8 [wt%]. Contains no acid components other than hypochlorous acid. Further, as a base component, ammonia was blended so as to have a molar ratio of the base component 1 to the acid component 2. The amount of the base component per unit mass in the liquid composition is 0.06 [mol / kg]. Other than that, it is the same as that of Preparation Example G1.

[Preparation Example H]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.15 [wt%]. Contains no acid components other than hypochlorous acid. Further, as a base component, triethylamine was blended so as to have a molar ratio of the base component 1 to the acid component 1. The amount of the base component per unit mass in the liquid composition is 0.02 [mol / kg]. The main solvent is diethylene glycol.

[Preparation Example K1]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.4 [wt%]. Contains no acid components other than hypochlorous acid. Further, as a base component, triethylamine was blended so as to have a molar ratio of the base component 1 to the acid component 1. The amount of the base component per unit mass in the liquid composition is 0.06 [mol / kg]. The main solvent is diethylene glycol.

[Preparation Example K2]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.4 [wt%]. Contains no acid components other than hypochlorous acid. Further, as a base component, triethylamine was blended so as to have a molar ratio of the base component 1 to the acid component 2. The amount of the base component per unit mass in the liquid composition is 0.03 [mol / kg]. Other than that, it is the same as Preparation Example K1.

[Preparation Example K3]
Hypophosphoric acid is added to the solvent and phthalic acid is added to the solvent so that the ratio of hypophosphoric acid is 0.4 [wt%] and the ratio of phthalic acid is 10 [wt%]. ], A liquid composition was prepared. Further, as a base component, triethylamine was blended so as to have a molar ratio of the base component 1 to the acid component 1. The amount of the base component per unit mass in the liquid composition is 0.7 [mol / kg]. Other than that, it is the same as Preparation Example K1.

[Preparation Example L]
Hypochlorous acid was added to the solvent, and a liquid composition was prepared so that the ratio of hypochlorous acid was 0.4 [wt%]. Contains no acid components other than hypochlorous acid. Further, as a base component, triethylamine was blended so as to have a molar ratio of the base component 1 to the acid component 2. The amount of the base component per unit mass in the liquid composition is 0.03 [mol / kg]. The main solvent is PEG200.

[Preparation example p]
Phosphoric acid was added to the solvent, and a predetermined liquid was prepared so that the ratio of phosphoric acid was 0.4 [wt%]. Does not contain hypochlorous acid. Moreover, the base component is not blended. The main solvent is diethylene glycol.

[Preparation example q]
Phosphoric acid was added to the solvent, and a predetermined solution was prepared so that the ratio of phosphoric acid was 0.4 [wt%]. Does not contain hypochlorous acid. Moreover, the base component is not blended. The main solvent is diethylene glycol.

[Preparation example r]
Phthalic acid was added to the solvent, and a predetermined solution was prepared so that the ratio of phthalic acid was 0.4 [wt%]. Does not contain hypochlorous acid. Further, as a base component, triethylamine was blended so as to have a molar ratio of the base component 1 to the acid component 2. The amount of the base component per unit mass in the predetermined liquid is 0.04 [mol / kg]. The main solvent is PEG200.

Next, the initial characteristics of each of the solid electrolytic capacitors of Examples 1 to 23 and Comparative Examples 1 to 3 described above were measured, and reflow of 10 [seconds] at a peak temperature of 260 [° C.] was performed twice in total. Then, the leakage current at the rated voltage application of 60 [seconds] was measured. Here, a product having a leakage current of 13 [μA] or less after reflow is defined as a low leakage current product after reflow, and the number of the corresponding products is counted. The results are shown in Table 1.

As shown in Table 1, when the number of samples was 20 each, in Examples 1 to 23, the yield of the low leakage current product after reflow was 100 [%]. On the other hand, when the number of samples was 20 each, the yields of the low leakage current products after reflow were only 30 [%] to 85 [%] in Comparative Examples 1 to 3. From the above results, in the configuration of the example in which hypophosphoric acid is added to the liquid composition, a low leakage current product after reflow, which is a low leakage current when heat treatment such as reflow is performed, can be obtained in high yield. found.

Next, the initial leakage current of each solid electrolytic capacitor of Examples 3, 16 and 20 having only hypophosphoric acid as an acid component was measured before reflow. Here, a product having a leakage current of 13 [μA] or less from the initial time before reflow is defined as a low leakage current product before reflow, and the number of the corresponding products is counted. The results are shown in Table 2.

As shown in Table 2, in Examples 3, 16 and 20 in which the number of samples is 20 and the acid component is hypochlorous acid only, the yield of the low leakage current product before reflow at the initial stage before reflow is performed. Became 100 [%]. From the above results, the configuration of the example in which the acid component consisting only of hypochlorous acid is added to the liquid composition is that a low leakage current product before reflow can be obtained in high yield regardless of the presence or absence of heat treatment such as reflow. There was found.

Next, with respect to Examples 1 to 4 and 8 in which the base component was not blended and Examples 14 to 23 in which the base component was blended in an amount equal to or less than the number of moles of the acid component, those to which hypophosphoric acid was not added were used as standard products. The rate of increase in capacitance with respect to the initial capacitance at a frequency of 120 [Hz] was compared. The results are shown in Table 3.

As shown in Table 3, it was confirmed that the initial capacitance was increased by adding hypochlorous acid to the liquid composition. In addition, by blending the base component in the liquid composition in an amount equal to or less than the number of moles of the acid component, the rate of increase in the initial capacitance became more than 1 [%]. From the above results, the configuration of the example in which hypophosphoric acid is added to the liquid composition and the basic component is blended in an amount equal to or less than the number of moles of the acid component has a low leakage current when heat treatment such as reflow is performed. It was found that the post-low leakage current product can be obtained in high yield and the initial capacitance can be made particularly large.

Next, the solids of Examples 1 to 4 and 8 in which the basic component was not blended and Examples 14, 15, 19, 21 and 23 in which the basic component was blended in an amount of less than 0.06 [mol / kg]. For the electrolytic capacitor, the ESR magnification by reflow was confirmed. The results are shown in Table 4.

As shown in Table 4, Examples 1 to 4 and 8 in which the base component was not blended and Examples 14, 15, 19, 21 in which the base component was blended in an amount of less than 0.06 [mol / kg], 23 has an ESR magnification of 1.3 or less due to reflow. From the above results, the configuration of the example in which hypophosphite is added to the liquid composition and the base component is not blended, or the hypophosphite is added to the liquid composition and the base component is less than 0.06 [mol / kg]. In the configuration of the example blended in the amount of, a high leakage current product after reflow, which is a low leakage current when heat-treated such as reflow, can be obtained in a high yield, and the ESR magnification by the heat treatment such as reflow is particularly high. It turned out to be small.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the present invention.

1 Solid Electrolyte Condenser 2 Capacitor Element 2a Anode Foil 2b Oxidation Film 2c Cathode Foil 2d Separator 2e Conductive Polymer Compound 3 Sealing Body 4 Case 5 Lead Terminal 6 Lead Terminal 20 Solid Electrolyte 30 Liquid Composition

Claims (5)

A solid electrolyte having an anode foil on which an oxide film is formed, a cathode foil, and a separator disposed between the anode foil and the cathode foil, and formed of a finely divided conductive polymer compound. The liquid composition is provided with a liquid composition introduced so as to surround the solid electrolyte, and the liquid composition contains an acid component and a base component, and the base component is contained in an amount equal to or less than the number of moles of the acid component. And,
A solid electrolytic capacitor characterized in that the acid component contains hypochlorous acid. A solid electrolyte having an anode foil on which an oxide film is formed, a cathode foil, and a separator disposed between the anode foil and the cathode foil, and formed of a finely divided conductive polymer compound. The liquid composition is provided with a liquid composition introduced so as to surround the solid electrolyte, and the liquid composition contains an acid component and a base component, and the base component is contained in an amount of less than 0.06 mol / kg. There,
A solid electrolytic capacitor characterized in that the acid component contains hypochlorous acid. A solid electrolyte having an anode foil on which an oxide film is formed, a cathode foil, and a separator disposed between the anode foil and the cathode foil, and formed of a finely divided conductive polymer compound. The liquid composition is provided with a liquid composition introduced so as to surround the solid electrolyte, the liquid composition contains an acid component, and the liquid composition does not contain a base component.
A solid electrolytic capacitor characterized in that the acid component contains hypochlorous acid. The solid electrolytic capacitor according to any one of claims 1 to 3, wherein the liquid composition contains a liquid polyol compound as a solvent. A solid electrolyte having an anode foil on which an oxide film is formed, a cathode foil, and a separator disposed between the anode foil and the cathode foil, and formed of a finely divided conductive polymer compound. A method for manufacturing a solid electrolytic capacitor including a liquid composition introduced so as to surround the solid electrolyte.
A method for producing a solid electrolytic capacitor, wherein the liquid composition contains hypophosphoric acid as an acid component to reduce a leakage current even after reflow.

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