JP2001148331A - Solid electrolytic capacitors - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface mounting solid electrolytic capacitor whose impedance characteristic is superior and whose high temperature surface mounting is stable. SOLUTION: This solid electrolytic capacitor is constituted in such a way that a solid electrolyte layer and a cathode lead are formed on an anode on which a dielectric oxide film layer is formed and that a capacitor element 10 whose moisture is prescribed at 1 wt.% or less in terms of weight is covered with a packaging member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a solid electrolyte such as manganese dioxide, a tetracyanoquinodimethane complex salt, a conductive polymer comprising polystyrenesulfonic acid and its derivatives, polyethylenedioxythiophene and its derivatives, polypyrrole and its derivatives. The present invention relates to a solid electrolytic capacitor used.

[0002]

2. Description of the Related Art With the increase in the frequency of electronic devices, electrolytic capacitors as electronic components have been required to have better impedance characteristics in a high frequency range than before. Recently, in order to reduce the impedance in the high frequency region, an electrolytic capacitor using a solid electrolyte such as a tetracyanoquinodimethane complex salt (hereinafter referred to as TCNQ) having high electric conductivity or a conductive polymer has been studied. I have. On the other hand, in response to the demand for increasing the capacity of the capacitor, a wound type (anode foil and a cathode foil are wound via a separator, which is structurally easier to increase the capacity compared to the case of laminating electrode foils) TCNQ and conductive polymer electrolytes have been applied to electrolytic capacitors of the same type), but the study of surface mounting has been delayed compared to electrolytic capacitors that use an electrolytic solution. The reason why surface mounting is difficult for a capacitor using a solid electrolyte has not been clarified technically.

[0003] This is because a solid electrolytic capacitor using TCNQ or a conductive polymer as a solid electrolyte has a surface mounted electronic component on a printed circuit board as compared with a capacitor using a liquid electrolyte having a vapor pressure (ie, an electrolytic solution). Since the capacitor element does not have a component that vaporizes under a high-temperature atmosphere (specifically, 200 ° C. or more) when soldering with the above, the pressure rise inside the outer case during surface mounting is small, and It is generally considered that problems such as swelling and damage to the sealing member are reduced and surface mounting is easy. However, in practice, a large amount of water is retained in the capacitor element itself during the manufacturing process because the solid electrolyte itself easily adsorbs moisture in the air, and this adsorbed moisture evaporates under high temperature conditions during surface mounting, The present inventors have found that surface mounting is more difficult than that of the type using an electrolytic solution, and have led to the present invention.

In order to take the above-mentioned wound structure, it is necessary to interpose a separator in order to avoid contact between the anode foil and the cathode foil. However, in a conventional electrolytic capacitor using an electrolytic solution as an electrolyte, From the viewpoint of emphasizing the ease of wetting with an electrolytic solution, it is known to use so-called electrolytic paper made of manila hemp or kraft paper made of a cellulose component having a high affinity for water as a separator. In addition, as a separator for a wound electrolytic capacitor using a conductive polymer as an electrolyte, a glass fiber nonwoven fabric, a resin nonwoven fabric adjusted by a melt blow method, and heating or the like after winding a capacitor element using the above electrolytic paper. It has been known that carbonized electrolytic paper or the like obtained by carbonizing this electrolytic paper by the method described above is used as a separator.

[0005]

However, in the above-mentioned conventional structure, the glass fiber nonwoven fabric used as the separator is originally made of silica having a high affinity for water. There is a problem that the capability of adsorbing moisture therein is large, and even after the solid electrolyte is formed, the water content of the capacitor element is high, which is not suitable for surface mounting. Furthermore,
This glass fiber non-woven fabric has the drawback that the needle-like glass fiber scatters around during cutting or winding, causing a large problem in the working environment, and also has the disadvantage that the strength at the time of bending due to winding is brittle and the product is likely to short-circuit. Had.

[0006] Since carbonized electrolytic paper is originally made of cellulose having a high affinity for water, it has a greater ability to adsorb moisture in the air than a resin-made separator. Even after the formation, the capacitor element has a problem that the water content of the capacitor element is high and is not suitable for surface mounting.

Further, when carbonizing the electrolytic paper, unless the heat exceeding 250 ° C. is applied to the capacitor element for a long time, a sufficient carbonized state is created to hold the solid electrolyte and reduce the impedance in a high frequency region. This heating damages the dielectric oxide film and increases the leakage current. In addition, this heating oxidizes the plating layer (for example, tin / lead layer) of the lead wire of the electrolytic capacitor. In the case of a plated wire, the solder wettability at the lead wire portion of the completed product is significantly reduced, and therefore, there is a problem that an expensive silver-plated lead wire having strong oxidation resistance must be used. .

Further, since the resin nonwoven fabric prepared by the melt blow method has a low ability to adsorb moisture in the air, the water content of the capacitor element after the solid electrolyte is formed is relatively low, and it is not suitable for surface mounting. Although it is easy to be oriented, it has a low tensile strength compared to electrolytic paper, so it is easy for the separator to break when winding the capacitor element, and due to the effect of the adhesive component used when bonding resin fibers together to form a sheet It is difficult to hold a solid electrolyte (especially a conductive polymer electrolyte) on a separator, and it has been difficult to manufacture a solid electrolytic capacitor having low impedance in a high-frequency region.

As the conductive polymer used for the electrolyte, polyethylene dioxythiophene and polypyrrole formed by chemically oxidizing and polymerizing ethylene dioxythiophene with an appropriate oxidizing agent are known. Since it is difficult to hold the resin separator made of polypropylene, it is difficult to increase the impedance due to the separation between the separator and the conductive polymer due to thermal stress or the like, and the capacity extraction rate is poor. However, the capacitor has a disadvantage that the size per capacity is larger than that of the capacitor.

The present invention solves such a conventional problem,
An object of the present invention is to provide a surface mount type solid electrolytic capacitor having excellent impedance characteristics and stable high temperature surface mount performance.

[0011]

In order to solve the above-mentioned problems, the present invention provides a solid electrolyte layer and a cathode lead portion on an anode electrode on which a dielectric oxide film layer is formed, and has a water content of 1 to 50% by weight. This is a solid electrolytic capacitor having a configuration in which a capacitor element specified in a weight percent or less is covered with an exterior member.

According to the present invention, a surface mount type solid electrolytic capacitor having excellent impedance characteristics and stable high temperature surface mount performance can be obtained.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION According to the first aspect of the present invention, a solid electrolyte layer and a cathode lead portion are provided on an anode electrode on which a dielectric oxide film layer is formed, and the amount of water is 1 wt. % Or less and a solid electrolytic capacitor composed of an exterior member coated with the capacitor element. According to this configuration, in the manufacturing process, the capacitor element having the solid electrolyte layer formed thereon is covered by the exterior member. In the inside of the hermetically sealed outer member (there is a capacitor element inside), which is formed by being sealed, the moisture contained in the capacitor element (specifically, the solid electrolyte which easily adsorbs moisture in the air) Is a component that evaporates and increases the pressure inside the hermetically sealed exterior member, so that the water content of the capacitor element that causes this The pressure increase inside the package member is less likely to occur even under high temperature conditions during surface mount by regulating the amount, an effect that can be exhibited stable surface mount capability.

According to a second aspect of the present invention, an anode foil and a cathode foil each having a dielectric oxide film layer formed thereon are wound through a separator, and a solid electrolyte layer is formed between the anode foil and the cathode foil. And a capacitor element having a water content of 1% by weight or less on a weight basis, a bottomed cylindrical metal outer case containing the capacitor element, and a polymer component sealing an opening of the outer case. According to this configuration, in the manufacturing process, the wound capacitor element in which the solid electrolyte is formed and wound is inserted into a metal outer case, and furthermore,
The inside of the sealed metal outer case (there is a wound capacitor element inside), which is formed by sealing the opening of the metal outer case, holds the wound capacitor element. Only the moisture that is generated (specifically, the contribution of the moisture possessed by the separator, which easily adsorbs moisture in the air more than the solid electrolyte) evaporates, increasing the pressure inside the sealed metal outer case. Since the amount of water contained in the wound capacitor element, which causes this, is regulated, the pressure inside the outer case hardly increases even under high temperature conditions during surface mounting, and stable surface mounting It can exhibit performance. In addition, the outer case made of a metal such as aluminum or an aluminum alloy has less plastic deformation due to an increase in the internal pressure.In addition to the above-described effects, the outer case is less likely to be deformed even under high temperature conditions during surface mounting. It is possible to exhibit more stable surface mounting performance.

Further, when curling is used for the opening of the outer case as a means for sealing the opening of the outer case made of metal, a sealing member containing an elastic polymer component is used. As a result, a stable sealing performance can be obtained, so that in addition to the above-described effects, deformation of the sealing surface hardly occurs even under a high temperature condition during surface mounting, and more stable surface mounting performance can be exhibited. It has the action of:

According to a third aspect of the present invention, in the second aspect of the present invention, the sealing member containing a polymer component is peroxide-cured and / or resin-cured and has an elastic modulus at 250 ° C. of 450N. / Cm ² or more, butyl rubber that has been vulcanized by peroxide and / or resin has high heat resistance, so that severe thermal stress during mounting can be reduced. A solid electrolyte capacitor with high reliability that does not promote deterioration of the sealing performance even after being added, hardly causes deterioration of the solid electrolyte due to the infiltration of moisture into the solid electrolytic capacitor over time, and Can be. Further, since the temperature at the time of mounting the solid electrolytic capacitor is usually in the range of 200 to 250 ° C., the temperature of the sealing rubber of the solid electrolytic capacitor is 250 ° C.
By setting the elastic modulus in the vicinity to 450 N / cm ² or more, the water content of the capacitor element evaporates during mounting, and the mechanical strength at that temperature is strong even when the internal pressure of the outer case rises. The deformation ratio due to the influence is small, and as a result, the appearance deformation of the solid electrolytic capacitor at the time of mounting can be suppressed, and an effect that stable surface mounting performance can be exhibited.

According to a fourth aspect of the present invention, the anode foil and the cathode foil each having the dielectric oxide film layer formed thereon are wound through a separator, and the solid electrolyte layer is formed between the anode foil and the cathode foil. A capacitor element, a bottomed cylindrical metal outer case containing the capacitor element, and butyl rubber having a vulcanized peroxide and / or a resin vulcanized and an elastic modulus at 250 ° C. of 450 N / cm ² or more. This is a solid electrolytic capacitor formed of a sealing member that is formed and seals the opening of the outer case. According to this configuration, the same effect as that of the invention according to the third aspect is obtained.

According to a fifth aspect of the present invention, there is provided the method according to any one of the second to fourth aspects, wherein the separator is made of a synthetic resin and has a thickness of 80 μm or less, and weighs 10 to 60 g. / M ² , and according to this configuration, synthetic resin (for example, polyester fiber (polyethylene terephthalate, polybutylene terephthalate, etc.), vinylon fiber, nylon fiber, rayon fiber, polyethylene) Fiber, polypropylene fiber, trimethylpentene fiber, polyphenylene sulfide fiber, and celluloid) have a very low water absorption rate in the air as compared with cellulose. Even for solid electrolytes, such as polymer electrolytes, which are susceptible to high-temperature oxygen degradation, 85 to a degree that does not lower the electrical conductivity
Drying of capacitor element at a temperature in the range of 125 ° C)
Therefore, it is easy to regulate the content to 1% by weight or less, and the use of the capacitor element formed using this separator has an effect that a solid electrolytic capacitor having stable mounting performance even in a high temperature atmosphere during surface mounting can be formed. .

When the thickness is set to a range exceeding 80 μm, the water absorption rate of the resin itself is small, but the effective water absorption area (the true surface area of the separator used per solid electrolytic capacitor) is increased. The amount of water absorption increases, and it is difficult to sufficiently exert the above-described effects. Further, when the thickness is set to a range exceeding 80 μm, even when an electrode foil having the same area is wound, the thickness of the separator becomes bulky, so that it becomes difficult to configure a solid electrolytic capacitor having a small diameter. It is also difficult to construct a solid electrolytic capacitor having a large capacity per volume.

Further, by limiting the weighing to the range of 10 to 60 g / m ² , a sufficient tensile strength is ensured even in a separator mainly composed of synthetic fibers to reduce the frequency of separator breakage during winding of the capacitor element. And the absolute water absorption of the separator can be restricted to a small range.
This has the effect that a solid electrolytic capacitor having stable mounting performance even in a high-temperature atmosphere during surface mounting can be formed.

If the weighing of the separator is less than 10 g / m ^2, it is not preferable because the separator often breaks during winding, and if the weighing exceeds 60 g / m ² , the effective water absorption area per unit area increases. The absolute water absorption increases, making it difficult to sufficiently exert the above-described effects.

The invention according to claims 6 and 7 is the invention according to claim 5, wherein the separator is a nonwoven fabric produced by a spunbonding method and a wet method containing a polyalkylene terephthalate resin and a derivative resin thereof. According to this configuration, among the synthetic resins, polyalkylene terephthalate resin (more preferably, polyethylene terephthalate resin and polybutylene terephthalate resin) has a particularly low water absorption rate, so that the water content of the capacitor element is small. (E.g., drying of a capacitor element in a temperature range of 85 to 125 ° C. to such an extent that the conductivity is not lowered even in a solid electrolyte such as a conductive polymer electrolyte which is easily deteriorated by high-temperature oxygen). Is easily regulated to 1% by weight or less. It can constitute a solid electrolytic capacitor having a very stable mounting performance even under a high temperature atmosphere at the time of surface mounting by using a capacitor element constituted by using the chromatography data.

Further, polyalkylene terephthalate resin and its derivative resin (more preferably, polyethylene terephthalate resin and polybutylene terephthalate resin)
Has excellent adhesion and adhesion to conductive polymers (for example, polyethylene dioxythiophene and polypyrrole). The impedance can be further reduced.

The nonwoven fabric produced by the spunbond method and the wet method is different from other synthetic resin nonwoven fabrics.
Since the sheet can be formed by a heat bonding method or a mechanical entanglement method without using an adhesive for bonding the fibers when forming the sheet, the solid electrolyte is hardly peeled off due to the influence of the adhesive component. It also has an effect that the solid electrolyte can be easily held by the separator and a solid electrolytic capacitor having a low impedance in a high frequency region can be formed.

Further, the nonwoven fabric produced by the spunbond method and the wet method has a single fiber length longer than that of the nonwoven fabric produced by the melt blow method, so that the same thickness,
When compared by weighing, there is an advantageous effect that the tensile strength is increased and the frequency of separator breakage during winding of the capacitor element is reduced.

According to an eighth aspect of the present invention, the polyalkylene terephthalate resin contains a polyethylene terephthalate resin and / or a polybutylene terephthalate resin, and the polyalkylene terephthalate resin has an improved wettability. According to this configuration, it is possible to adjust the water absorption of the separator by the wettability improving treatment of the separator. The effect of the invention described can be further enhanced.

According to a ninth aspect of the present invention, there is provided the electroconductive device according to any one of the first to eighth aspects, wherein the solid electrolyte comprises manganese dioxide, a tetracyanoquinodimethane complex salt, polystyrenesulfonic acid and a derivative thereof. The composition comprises at least one selected from the group consisting of a conductive polymer, polyethylene dioxythiophene and a derivative thereof, and polypyrrole and a derivative thereof. According to this configuration, the solid electrolyte is a solid electrolyte. Among them, since the water absorption is relatively low, it is possible to construct a solid electrolytic capacitor that has extremely stable mounting performance even in a high temperature atmosphere during surface mounting by using a capacitor element manufactured using this solid electrolyte. Has an action. The solid electrolyte formed by drying the water-soluble polyaniline has a high compatibility with water of the original polymer component, and therefore has a high water absorption, and it is difficult to sufficiently exert the above-described effects.

The invention described in claim 10 is the invention according to claims 1 to 9
In the invention according to any one of the above, the solid electrolyte is at least an anode foil, a cathode foil, at least one or more selected from the group of separators containing a binder component for reducing water absorption. Things,
The invention according to claim 11 is the invention according to claim 10, wherein the binder component for reducing water absorption is polycarbonate, polyacrylate, polymethacrylate, polystyrene, polyurethane, polyacrylonitrile, polybutadiene, polyisoprene, Polyether, polyester, polyethylene terephthalate, polybutylene terephthalate, polyamide, polyimide,
Butyral resin, silicone resin, melamine resin, alkyd resin, bisphenol A type epoxy, bisphenol F type epoxy, alicyclic epoxy and a polymer or a copolymer containing at least one selected from the group consisting of derivatives thereof According to this configuration, according to this configuration, it is difficult for these polymers or copolymers composed thereof to absorb moisture because they are hydrophobic, and at least the anode foil, the cathode foil, and the separator are selected from the group. Since the water absorption of the capacitor element can be reduced by incorporating these binder components into at least one or more of them, a method of relatively easily reducing the water content of the capacitor element (for example, such as a conductive polymer electrolyte) Even in a solid electrolyte which is susceptible to high-temperature oxygen deterioration, a value of 85 to 85 which does not decrease the conductivity of the solid electrolyte. (A drying treatment of the capacitor element at a temperature in the range of 25 ° C.) to easily regulate the content to 1% by weight or less, and also prevent moisture in the air from being re-adsorbed to the capacitor element in a shelf state after drying. This has the effect that a solid electrolytic capacitor having very stable mounting performance even in a high-temperature atmosphere during surface mounting can be formed.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIG.

FIG. 1 is a partial cross-sectional perspective view showing a surface mount type solid electrolytic capacitor according to an embodiment of the present invention. As shown in FIG. A capacitor element 10 is formed by winding through a separator 3 an anode foil 1 made of an aluminum foil having a dielectric oxide film layer formed thereon and a cathode foil 2 obtained by etching the aluminum foil. Also, between the anode foil 1 and the cathode foil 2 (the anode foil 1
The solid electrolyte layer 4 made of TCNQ, a conductive polymer, or the like is formed (to make contact with the cathode foil 2) to form the capacitor element 10.

The capacitor element 10 is housed in a bottomed cylindrical outer case 8, and the open end of the outer case 8 is led out of each of the anode foil 1 and the cathode foil 2 by the sealing member 7 for external lead-out. 5 and the cathode lead 6 are sealed so as to penetrate the sealing member 7, and the anode plate 5 and the cathode lead 6 are further sealed so that the seat plate 9 penetrates the seat plate 9.
Are arranged, and at least a part of the external lead-out portion of the anode lead 5 and the cathode lead 6 is bent flat to form a surface-mount type solid electrolytic capacitor.

Next, specific embodiments of the present invention will be described, but the present invention is not limited thereto. Hereinafter, all parts are by weight.

(Embodiment 1) A polyethylene terephthalate spun bond separator (thickness: 50 μm, weighing 25 g / m ² ) is interposed between an anode foil and a cathode foil, and the outer periphery of the wound capacitor element A winding type capacitor element was formed by winding using a polyphenylene sulfide base material adhesive tape having a length 1.5 times as long as the above (this capacitor element was impregnated with a 10% by weight ethylene glycol solution of ammonium adipate). The capacitance at a frequency of 120 Hz when this was performed was 670 μF.)

Subsequently, a solution containing 1 part of ethylenedioxythiophene as a heterocyclic monomer, 2 parts of ferric p-toluenesulfonate as an oxidizing agent, and 4 parts of n-butanol as a polymerization solvent was prepared. After being immersed and pulled up, polyethylene dioxythiophene, a chemically polymerizable conductive polymer, was formed between the electrode foils by being left at 85 ° C. for 60 minutes.

Subsequently, the capacitor element was washed with water and dried, and then subjected to a drying treatment at 120 ° C., which is a temperature higher than the boiling points of n-butanol and water, for 30 minutes. Immediately after this operation, the capacitor element was immediately transferred into a dry air glove box, and dried in a dry air atmosphere at 120 ° C. for 1 hour in advance to seal the resin vulcanized butyl rubber having a reduced moisture content. Material (30 parts of butyl rubber polymer, 20 parts of carbon, 50 parts of inorganic filler, hardness: 70 IRHD [International rubber hardness unit],
After sealing in an aluminum alloy outer case together with an elastic modulus of 450 N / cm ^{2 at} 250 ° C.), the openings were sealed by curling treatment, and both leads respectively derived from the anode foil and the cathode foil were made of polyphenylene sulfide. By passing the lead through the seat plate and bending the lead portion flat, a surface mount type solid electrolytic capacitor was produced (size: diameter 10 mm × height 10.2 mm).

The solid electrolytic capacitor thus manufactured is disassembled in the dry air glove box used for the above assembly so as not to adsorb moisture in the air, and the capacitor element is taken out. The moisture content of the capacitor element is taken out. Was measured by the N ₂ gas introduction Karl Fischer method equipped with a moisture vaporization heating device, and the anode foil portion, the cathode foil portion, the separator, the solid electrolyte of the capacitor element,
Sum of the weights of the tapes (ie, the weight of the capacitor element excluding the weight of the anode and cathode leads)
The standard was 0.80% (hereinafter, the moisture content derived by this measurement method is referred to as W1).

Further, for the purpose of verifying the measurement accuracy of the moisture content obtained in this manner, the capacitor element obtained by removing both the anode and cathode leads from the above-mentioned capacitor element,
The weight after drying at 120 ° C. for 1 hour was subtracted from the weight before drying, and this value was divided by the weight before drying to obtain a weight change percentage (weight corresponding to the amount of water adsorbed on the capacitor element). The moisture percentage derived by this measurement method, which can be estimated as a percentage, is hereinafter referred to as W2) was 0.81% on a weight basis. From this result, it can be seen that the moisture content could be grasped with extremely high accuracy.

(Embodiment 2) In Embodiment 1, 1 part of ferric naphthalenesulfonate and 1 part of ferric triisopropylnaphthalenesulfonate are used as the oxidizing agent.
Embodiment 1 Except that 4 parts of ethanol was used as a polymerization solvent.
It was prepared in the same manner as The water content W1 according to the second embodiment was 0.89%, and W2 was 0.89%.

(Embodiment 3) In Embodiment 1, 1 part of pyrrole is used as a heterocyclic monomer, 2 parts of ammonium persulfate is used as an oxidizing agent, and a mixed solvent of 1 part of methanol and 3 parts of water is used as a polymerization solvent. Except for the above, it was manufactured in the same manner as in the first embodiment. The water content W1 according to the third embodiment is 0.88%,
W2 was 0.88%.

(Embodiment 4) A semiconductor device was manufactured in the same manner as in Embodiment 1 except that a polypropylene spunbond separator (thickness 50 μm, weighing 25 g / m ² ) was used as the separator. The water content W1 according to the fourth embodiment was 0.94%, and W2 was 0.94%.

(Embodiment 5) A production was performed in the same manner as in Embodiment 1, except that nitrated cellulose fiber paper obtained by nitrifying nitrile-treated Manila hemp electrolytic paper was used as the separator. The water content W1 according to the fifth embodiment is equal to 0.
97% and W2 were 0.96%.

(Embodiment 6) The procedure of Embodiment 1 was repeated, except that a glass fiber nonwoven fabric (80 μm thick, weighing 10 g / m ² ) was used as the separator. The water content W1 according to the sixth embodiment is 0.97.
% And W2 were 0.97%.

(Embodiment 7) In the first embodiment, electrolytic paper (thickness: 50 μm) made of manila hemp is wound between the anode foil and the cathode foil, and the capacitor element is placed in a nitrogen atmosphere. After heating at 275 ° C. for 2 hours to carbonize the electrolytic paper interposed between the electrode foils to form a capacitor element, this capacitor element was converted to a solid content of polyethylene dioxythiophene polystyrene sulfonic acid, which is a derivative of polystyrene sulfonic acid. 0.3% aqueous solution (Baytron P [trade name] manufactured by Bayer AG) and a suspension solution of sulfonic acid-modified polyethylene terephthalate as a binder component for reducing water absorption (aqueous solution having a solid content of 5.0%): (1) After adding a step of immersing and lifting in a mixed solution and drying it at 150 ° C. for 10 minutes, a heterocyclic monomer was added. In a ethylenedioxythiophene 1 parts of a oxidizing agent p- toluenesulfonic acid ferric 2
Immersed in a solution containing 4 parts of n-butanol as a polymerization solvent and raised, and then left at 85 ° C. for 60 minutes to form polyethylene dioxythiophene, a chemically polymerizable conductive polymer, between the electrode foils. Embodiment 1 except for
It was prepared in the same manner as The water content W1 according to the seventh embodiment was 0.78%, and W2 was 0.77%.

(Eighth Embodiment) In the first embodiment, the sealing member is made of peroxide-cured butyl rubber using dicumyl peroxide as a vulcanizing agent (32 parts of butyl rubber polymer, 20 parts of carbon). , Inorganic filler 48
And a hardness of 68 IRHD (international rubber hardness unit) and an elastic modulus of 400 N / cm ^{2 at} 250 ° C.). The water content W1 according to the eighth embodiment is 0.79%, and W2 is 0.78%.
Met.

(Embodiment 9) In Embodiment 1 described above, assembly was performed in an environment of a temperature of 30 ° C. and a relative humidity of 60% RH without moving into a dry air glove box (immediately after the capacitor element was dried). Except that the time required from assembly to assembly was 1.0 hour). The water content W1 according to the ninth embodiment is 1.2%, W
2 was 1.1%.

(Embodiment 10) In Embodiment 1, 1 part of ethylenedioxythiophene as a heterocyclic monomer, 2 parts of ferric p-toluenesulfonate as an oxidizing agent, and n-type as a polymerization solvent Same as Embodiment 1 except that a solution containing 4 parts of butanol and 1 part of a suspension of carboxylic acid-modified polyethylene terephthalate (aqueous solution having a solid concentration of 30%) is added as a binder component for reducing water absorption. Prepared. The water content W1 according to the tenth embodiment was 0.75%, and W2 was 0.73%.

Embodiment 11 A nonwoven fabric separator (thickness: 50 μm, weighing: 22.5 g / m ² ) manufactured by the wet method using polyethylene terephthalate fiber and its derivative fiber as the separator in Embodiment 1 described above.
Except for using, the same procedure as in Embodiment 1 was used. According to the eleventh embodiment, the water content W1 is 0.90%, and W2 is 0.1%.
It was 91%.

(Comparative Example 1) A wound capacitor element was formed by winding a polyethylene terephthalate spunbond separator (thickness: 50 μm, weighing 25 g / m ² ) between an anode foil and a cathode foil. (A frequency of 12% when this capacitor element was impregnated with a 10% by weight solution of ammonium adipate in ethylene glycol).
The capacitance at 0 Hz was 670 μF. ).

Subsequently, a solution containing 1 part of ethylenedioxythiophene as a heterocyclic monomer, 2 parts of ferric p-toluenesulfonate as an oxidizing agent, and 4 parts of n-butanol as a polymerization solvent was prepared. After being immersed and pulled up, polyethylene dioxythiophene, a chemically polymerizable conductive polymer, was formed between the electrode foils by being left at 85 ° C. for 60 minutes.

Subsequently, the capacitor element was washed with water and dried, and then subjected to a drying treatment at 120 ° C., which is a temperature not lower than the boiling point of n-butanol as a polymerization solvent, for 30 minutes. Subsequent to this operation, the capacitor element was sealed in a resin vulcanized butyl rubber sealing member (containing 32 parts of butyl rubber polymer, 20 parts of carbon, and 48 parts of inorganic filler) in an atmosphere of a temperature of 30 ° C. and a relative humidity of 60% RH, and a hardness of 68 IRHD. [International rubber hardness unit], elastic modulus 400 N / c at 250 ° C
m ² ), sealed in an aluminum alloy outer case, sealed the opening by curling treatment, and passed both lead terminals respectively derived from the anode foil and the cathode foil through a polyphenylene sulfide seat plate. The surface-mount type solid electrolytic capacitor was manufactured by bending the portion flat. (Size: diameter 10 mm × height 10.2)
mm). The moisture content W1 according to Comparative Example 1 was 1.2%, W2
Was 1.1%.

With respect to the solid electrolytic capacitors of Embodiments 1 to 11 of the present invention and Comparative Example 1 manufactured as described above, the capacitance (measuring frequency: 120 Hz), impedance (measuring frequency: 100 kHz), and surface mounting soldering were used. Of the sealing surface of the solid electrolytic capacitor after performing a reflow treatment (condition of 45 seconds exposed to a peak temperature of 250 ° C. or more than 200 ° C.) for the soldering and the lead floating at the time of mounting due to the swelling of the sealing surface. Table 1 shows the result of comparing the number of defective solders.

Each of the test pieces was 50 pieces.
The capacitance, the impedance, and the swelling amount of the sealing surface of the solid electrolytic capacitor were represented by an average value of 50 pieces.

[0053]

[Table 1]

As is clear from Table 1, the solid electrolytic capacitors according to the first to eighth and tenth to eleventh embodiments of the present invention have a water content of 1% by weight based on the weight of the capacitor element. % Or less, and the capacitor element is housed in the outer case and the opening of the outer case is sealed, so that the pressure inside the outer case hardly increases even under high temperature conditions during surface mounting. As a result, the swelling amount of the sealing surface of the solid electrolytic capacitor compared to Comparative Example 1 (plastic deformation of the sealing surface due to an increase in internal pressure)
Is small, and it can be seen that the swelling amount is controlled to be equal to or less than the swelling amount (= 0.20 mm) at which a problem occurs at the time of mounting. In addition, due to this effect, a solid electrolytic capacitor having stable high-temperature mounting performance could be formed without occurrence of soldering failure due to lead floating during mounting due to bulging of the sealing surface.

In the solid electrolytic capacitors according to the first to seventh and ninth to eleventh embodiments of the present invention, the opening of the outer case has an elastic modulus of 450 N / cm ² at 250 ° C.
Since the above structure is used for sealing using the peroxide-vulcanized butyl rubber sealing member, the temperature at the time of mounting (24
Even at 5 ° C.), sufficient mechanical strength of the sealing surface can be ensured. As a result, as compared with Comparative Example 1, the amount of swelling of the sealing surface of the solid electrolytic capacitor (plastic deformation of the sealing surface due to an increase in internal pressure)
Is small, and the swelling amount (=
0.20 mm) or less. In addition, due to this effect, a solid electrolytic capacitor having stable high-temperature mounting performance could be formed without occurrence of soldering failure due to lead floating during mounting due to bulging of the sealing surface.

The solid electrolytic capacitors according to the seventh and tenth embodiments of the present invention have a modified polyethylene terephthalate resin which is a kind of polyester as a binder component for reducing water absorption in the solid electrolyte, in addition to the above-mentioned effects. As a result, the moisture content of the capacitor element can be controlled to a minimum, and as a result, the amount of swelling of the sealing surface during mounting is minimized, and a solid electrolytic capacitor having more stable high-temperature mounting performance is configured. We were able to.

According to the present invention, a surface mount type solid electrolytic capacitor having excellent impedance characteristics and stable high temperature surface mount performance can be obtained.

[0058]

As described above, in the solid electrolytic capacitor of the present invention, the solid electrolyte layer and the cathode lead portion are provided on the anode electrode on which the dielectric oxide film layer is formed, and the water content is 1% by weight or less on a weight basis. By adopting a configuration in which the capacitor element specified in (1) is covered with an exterior member, a surface mount type solid electrolytic capacitor having excellent impedance characteristics and stable high temperature surface mount performance can be obtained, and its industrial value is large. It becomes.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional perspective view showing a configuration of a solid electrolytic capacitor according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode foil 2 Cathode foil 3 Separator 4 Solid electrolyte layer 5 Anode lead 6 Cathode lead 7 Sealing member 8 Outer case 9 Seat plate 10 Capacitor element

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01G 9/10 H01G 9/02 331E 9/05 G (72) Inventor Yuki Murata 1006 Odakadoma, Kazuma, Kadoma, Osaka Address Matsushita Electric Industrial Co., Ltd. (72) Inventor Munehiro Morihiro 1006 Ojidoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (11)

[Claims] 1. A capacitor element having a solid electrolyte layer and a cathode lead portion provided on an anode electrode having a dielectric oxide film layer formed thereon and having a water content of 1% by weight or less on a weight basis, and the capacitor element is coated. Solid electrolytic capacitor consisting of exterior members. 2. An anode foil and a cathode foil each having a dielectric oxide film layer formed thereon are wound around a separator, a solid electrolyte layer is formed between the anode foil and the cathode foil, and the amount of water is determined by weight. A capacitor element of 1% by weight or less, a metal outer case having a bottomed cylindrical shape containing the capacitor element, and a sealing member containing a polymer component that seals an opening of the outer case. Solid electrolytic capacitor. 3. The sealing member containing a polymer component, wherein butyl rubber which is peroxide-cured and / or resin-cured and has an elastic modulus at 250 ° C. of 450 N / cm ² or more is used. Solid electrolytic capacitors. 4. A capacitor element in which an anode foil and a cathode foil on which a dielectric oxide film layer is formed are wound via a separator, and a solid electrolyte layer is formed between the anode foil and the cathode foil. And an opening of the outer case formed by butyl rubber having a modulus of elasticity of 450 N / cm ² or more at 250 ° C., which is vulcanized with a peroxide and / or resin and has a modulus of 450 N / cm ² or more. Solid electrolytic capacitor consisting of a sealing member whose part is sealed. 5. A separator having a thickness of not more than 80 μm mainly composed of a synthetic resin and weighing 10 to 60 g /
The solid electrolytic capacitor according to any one of claims 2-4 is in the range of m ^2. 6. The solid electrolytic capacitor according to claim 5, wherein the separator is a nonwoven fabric produced by a spunbond method containing a polyalkylene terephthalate resin and a derivative resin thereof. 7. The solid electrolytic capacitor according to claim 5, wherein the separator is a nonwoven fabric produced by a wet method containing a polyalkylene terephthalate resin and a derivative resin thereof. 8. The polyalkylene terephthalate resin and the derivative resin thereof contain a polyethylene terephthalate resin and / or a polybutylene terephthalate resin and have been subjected to a surface treatment for improving wettability. 8. The solid electrolytic capacitor according to 7. 9. The solid electrolyte, wherein the solid electrolyte is at least one selected from the group consisting of manganese dioxide, a tetracyanoquinodimethane complex salt, a conductive polymer composed of polystyrenesulfonic acid and its derivatives, polyethylenedioxythiophene and its derivatives, and polypyrrole and its derivatives. The solid electrolytic capacitor according to any one of claims 1 to 8, comprising at least one. 10. The solid electrolyte according to claim 1, wherein at least one selected from the group consisting of an anode foil, a cathode foil and a separator contains a binder component for reducing water absorption. 4. The solid electrolytic capacitor according to any one of the above. 11. A binder component for reducing water absorption, wherein polycarbonate, polyacrylate, polymethacrylate, polystyrene, polyurethane, polyacrylonitrile, polybutadiene, polyisoprene, polyether, polyester, polyethylene terephthalate, polybutylene terephthalate, polyamide, Polymer or copolymer containing at least one selected from the group consisting of polyimide, butyral resin, silicone resin, melamine resin, alkyd resin, bisphenol A epoxy, bisphenol F epoxy, alicyclic epoxy and derivatives thereof The solid electrolytic capacitor according to claim 10, which is a united product.