JP5354085B2 - Solid electrolytic capacitor - Google Patents

Description

  The present invention relates to a solid electrolytic capacitor used in various electronic devices.

  In recent years, with the development of digital equipment, a capacitor having a low equivalent series resistance (hereinafter referred to as ESR) and excellent high-frequency characteristics has been strongly demanded. In response to such market demand, an electrolyte using a solid electrolyte layer such as manganese dioxide, polypyrrole, or polythiophene has been developed and commercialized.

  FIG. 2 is a cross-sectional view showing the structure of this type of conventional solid electrolytic capacitor. In FIG. 2, an anode body 1 obtained by sintering a valve action metal such as aluminum or tantalum into a porous body, An anode lead-out line 1a in which one end is buried and the other end is exposed, a dielectric oxide film layer 2 formed on the surface of the anode body 1 by an anodic oxidation method, and the dielectric oxide film A solid electrolyte layer 3 containing a conductive polymer such as polypyrrole provided on the surface of the layer 2 by electrolytic polymerization and / or chemical polymerization, and a cathode layer 4 sequentially formed on the surface of the solid electrolyte layer 3 The capacitor element 5 is constituted by the carbon layer 4a and the conductive layer 4b of silver paste. The capacitor element 5, the anode terminal 6 connected to the anode lead-out line 1a, the cathode terminal 8 connected to the conductor layer 4b constituting the cathode layer 4, and the anode terminal 6 and the cathode terminal 8 are respectively A solid electrolytic capacitor is constituted by the insulating exterior resin 9 covering the entire capacitor element 5 so as to expose the connecting portion 6a and the connecting portion 8a connected to the electronic circuit.

  The solid electrolytic capacitor having the above-described configuration has a feature that the specific resistance of the solid electrolyte layer 3 is extremely low. Therefore, it is said that the ESR characteristic of the solid electrolytic capacitor can be reduced.

  Also, a small amount of a surfactant is mixed into the carbon layer 4a, or a surfactant layer is provided between the carbon layer 4a and the solid electrolyte layer 3, and a polyethylene glycol lauryl ether is used as the surfactant. By doing so, it is said that the adhesion of the carbon layer 4a to the solid electrolyte layer 3 is initially improved, and tan δ of the solid electrolytic capacitor can be reduced and the capacitance appearance rate can be improved. As such a conventional technique, for example, one described in Patent Document 1 is known.

JP-A-3-159222

  However, the above-described conventional solid electrolytic capacitor contains polyethylene glycol lauryl ether in the carbon layer 4a, thereby reducing ESR as well as reducing the tan δ of the solid electrolytic capacitor and improving the capacitance appearance rate. However, in the case of a high temperature environment, there is a problem that ESR changes with time and becomes large.

  The main cause of this problem is that the carbon layer 4a formed on the solid electrolyte layer 3 containing the conductive polymer is likely to be peeled off in a high temperature environment, and the interface resistance between the solid electrolyte layer 3 and the carbon layer 4a is low. This is because the specific resistance of the solid electrolyte layer 3 itself increases due to external oxygen and moisture entering from the gap with the solid electrolyte layer 3 formed by the separation of the carbon layer 4a. The ESR of the electrolytic capacitor tends to change and increase with time.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a solid electrolytic capacitor in which a change with time of ESR is small even under a high temperature environment.

  In order to achieve this object, the present invention includes an anode body made of a valve metal, a dielectric oxide film layer formed on the surface of the anode body, and a surface of the dielectric oxide film layer. In a solid electrolytic capacitor having a solid electrolyte layer containing a dopant, and a capacitor element comprising a carbon layer and a conductor layer sequentially formed as a cathode layer on the surface of the solid electrolyte layer, the carbon layer is an aromatic sulfonic acid. The solid electrolytic capacitor includes at least one additive selected from formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof, and the additive has a configuration different from that of the dopant.

  As described above, according to the present invention, the carbon layer has a configuration containing at least one selected from aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof, even in a high-temperature environment. Since the adhesion of the carbon layer to the solid electrolyte layer is maintained, peeling of the carbon layer can be suppressed. As a result, it is possible to prevent an increase in the interfacial resistance between the solid electrolyte layer and the carbon layer, and to prevent an increase in the specific resistance of the solid electrolyte layer itself by suppressing the intrusion of external oxygen and moisture. Can be obtained.

Sectional drawing which shows the structure of the solid electrolytic capacitor in Embodiment 1 of this invention Sectional view showing the structure of a conventional solid electrolytic capacitor

(Embodiment 1)
Hereinafter, the present invention will be described using Embodiment 1 with reference to the drawings.

  FIG. 1 is a cross-sectional view showing the configuration of the solid electrolytic capacitor in the first embodiment.

  In FIG. 1, 11 is an anode body made of a foil of valve action metal such as aluminum, the surface is roughened by etching, the surface area is enlarged, and an end portion thereof is an anode lead portion 11a. The anode lead portion 11a and the anode body 11 are separated on the foil surface by an insulating resist material 20 provided so as to be in close contact with the surface of the foil.

  Reference numeral 12 denotes a dielectric oxide film layer, which is formed by an oxide film obtained by subjecting the surface of the anode body 11 to chemical conversion treatment.

  A solid electrolyte layer 13 is formed on the surface of the dielectric oxide film layer 12. The solid electrolyte layer 13 includes a precoat layer such as a manganese dioxide layer and a conductive polymer layer such as polypyrrole, polythiophene, and polyaniline.

  A cathode layer 14 is formed on the surface of the solid electrolyte layer 13 and serves as a cathode lead portion. The cathode layer 14 includes a carbon layer 14a sequentially formed on the surface of the solid electrolyte layer 13, and a conductor layer 14b containing conductive particles such as silver and nickel. Sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or at least one of these salts is contained, and specific examples include naphthalene sulfonic acid formalin condensate, arylphenol sulfonic acid formaldehyde condensate, phenol sulfonic acid Examples include formaldehyde condensate, anthraquinone sulfonic acid formaldehyde condensate, naphthalene sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, and sodium salts thereof.

  In this way, the capacitor element 15 is configured, and the anode terminal 16 is connected to the anode lead portion 11a of the capacitor element 15 and the cathode terminal 18 is connected to the conductor layer 14b constituting the cathode layer 14, respectively. The entire capacitor element 15 is covered with an insulating exterior resin 19 so that the terminal 16 and the cathode terminal 18 are connected to the electronic circuit so that the connection portion 16a and the connection portion 18a are exposed, thereby forming a solid electrolytic capacitor. .

  Next, a method for manufacturing the solid electrolytic capacitor according to Embodiment 1 configured as described above will be described with reference to FIG.

  First, a foil made of valve metal such as aluminum whose surface area is expanded by etching treatment is cut into a certain width and length to form an anode body 11, and a tape-like insulating resist material 20 is formed on the outer surface of the anode body 11. By pasting, the anode body 11 and the anode lead portion 11a provided at the end thereof are separated.

  Next, the anode body 11 is immersed in a solution such as an aqueous solution of ammonium dihydrogen phosphate, and a direct current voltage is applied to perform a chemical conversion treatment to form an oxide film on the surface of the anode body 11 to form a dielectric oxide film layer. Get 12.

  Thereafter, the anode body 11 on which the dielectric oxide film layer 12 is formed is dipped in a manganese nitrate aqueous solution and pulled up, and then excess manganese nitrate aqueous solution adhering to the surface is removed, followed by heat decomposition at about 300 ° C. By performing the treatment, a manganese dioxide layer is formed on the dielectric oxide film layer 12 to form a precoat layer of the solid electrolyte layer 13 described later.

  Next, a conductive polymer layer made of polypyrrole or the like is formed on the manganese dioxide layer formed as the precoat layer by an electrolytic polymerization method, and the solid electrolyte layer 13 is provided.

  Thereafter, submicron carbon particles are dispersed in an aqueous solution at 2 to 10 wt%, and a carbon aqueous solution in which at least one of the above-described aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof and carbon particles are turbid. The carbon aqueous solution is applied to the surface of the solid electrolyte layer 13 and dried at a high temperature of 130 ° C. to 215 ° C. to remove the solvent component and form the carbon layer 14a. As a method of applying the carbon aqueous solution to the surface of the solid electrolyte layer 13, the anode body 11 in which the solid electrolyte layer 13 is formed in the carbon aqueous solution is immersed, or a member such as a roller or sponge holding the carbon aqueous solution is used as the solid electrolyte layer 13 For example, there is a method of contacting the anode body 11 formed up to the above.

  Next, a conductive paste made of conductive particles such as silver and nickel and an epoxy resin is applied and cured on the carbon layer 14a to form a conductive layer 14b. The carbon layer 14a and the conductive layer 14b Is used as a cathode layer 14 to obtain a capacitor element 15.

  Thereafter, one end portion of the anode terminal 16 is connected to the anode lead portion 11 a provided at the end portion of the anode body 11, while the conductive adhesive 17 is interposed on the conductor layer 14 b constituting the cathode layer 14. Then, one end of the cathode terminal 18 is connected.

  Next, the other end of each of the anode terminal 16 and the cathode terminal 18 can be brought into contact with the electronic circuit board, and the other end is exposed to the connection portion 16a and the connection portion 18a connected to the electronic circuit. Then, the entire capacitor element 15 is covered with an insulating exterior resin 19 made of an epoxy resin or the like to produce a solid electrolytic capacitor.

  The anode body 11 uses a foil made of a valve metal, but is made of a porous sintered body made of a powder of a valve metal such as aluminum, tantalum, or titanium. The lead wire made of the working metal may be embedded in the anode body 11 so that a part of the lead wire is exposed, and the anode lead portion 11a may be formed.

  The conductive polymer forming the solid electrolyte layer 13 is a polymerization selected from at least one of pyrrole, thiophene, aniline, furan or derivatives thereof such as 3,4-ethylenedioxythiophene as a heterocyclic monomer. It is formed by an electrolytic polymerization method or a chemical oxidative polymerization method using a functional monomer.

  In the electrolytic polymerization method, a solid electrolyte of a conductive polymer is formed by supplying power from the outside in a polymerization solution containing a polymerizable monomer and a dopant.

  The chemical oxidative polymerization method involves impregnating a polymerization solution of a polymerizable monomer and then forming a conductive polymer using a method of impregnating a mixed solution of a dopant and an oxidizing agent or a compound solution of a dopant and an oxidizing agent. To do.

  As the dopant, an aromatic compound having at least one of a carboxyl group and a sulfonic acid group is used.

  In addition, as an aromatic compound having a sulfonic acid group used as a dopant, benzenesulfonic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, butylnaphthalenesulfonic acid, phenolsulfonic acid, sulfosalicylic acid, sulfobenzoic acid, naphthalene disulfonic acid, benzene It can be selected from compounds such as disulfonic acid and anthraquinone disulfonic acid, derivatives thereof, or salt compounds such as sodium salt, potassium salt and ammonium salt thereof.

  In addition, as an aromatic compound having a carboxyl group used as a dopant, from a compound such as benzoic acid, phthalic acid, sulfophthalic acid, hydroxybenzoic acid, or a derivative thereof, or a salt compound such as a sodium salt, potassium salt, or ammonium salt thereof You can choose.

  Further, as the oxidizing agent, for example, ferric salt, persulfate, permanganate, hydrogen peroxide, etc. are used. As the ferric salt, iron sulfate, p-toluenesulfonic acid, butylnaphthalenesulfonic acid, An iron salt with a dopant such as anthraquinone sulfonic acid can be used.

  In addition, as another conductive polymer, a conductive polymer may be formed using a solubilized conductive polymer such as polyaniline having an imino-p-phenylene structure.

  Further, instead of the manganese dioxide layer formed as the precoat layer of the solid electrolyte layer 13, a precoat layer may be formed using a conductive material such as a conductive polymer.

  The carbon particles contained in the carbon layer 14a are selected from graphite, carbon black, and graphite.

  Moreover, in the formation process of the carbon layer 14a, a method using a carbon paste may be used, and an organic binder such as an acrylic resin, a polyester resin, an epoxy resin, a urethane resin, or a vinyl acetate resin is used in an organic solvent composed of butyl acetate, alcohol, ketone, or the like. Then, carbon paste is added to 20 to 90 wt%, and a carbon paste in which at least one of aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof is mixed is used to form the carbon paste up to solid electrolyte layer 13. The carbon layer 14a is formed by applying to the anode body 11 and curing at high temperature.

  The carbon layer 14a may contain an aromatic compound represented by the general formula (Chemical Formula 1) in addition to at least one of aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof. In this case, in the method of using the carbon aqueous solution in the formation process of the carbon layer 14a, carbon is dispersed in the aqueous solution at 2 to 10 wt%, and the aromatic sulfonic acid and / or its salt formaldehyde condensate and the general formula (Formula 1) A carbon aqueous solution in which an aromatic compound represented by the formula is turbid may be used. In order to dissolve the aromatic compound represented by the general formula (Chemical Formula 1), a surfactant may be added, and for example, a monohydric alcohol such as methanol, ethanol, isopropyl alcohol may be added. it can.

  With the configuration and the manufacturing method as described above, the carbon layer 14a contains at least one of aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof, so that the solid electrolyte can be used even in a high temperature environment. Since the adhesion of the carbon layer 14a to the layer 13 is maintained, peeling of the carbon layer 14a can be suppressed. As a result, it is possible to prevent an increase in the interfacial resistance between the solid electrolyte layer 13 and the carbon layer 14a, and to prevent an increase in the specific resistance of the solid electrolyte layer 13 by suppressing the intrusion of external oxygen and moisture. There is an effect that it is possible to obtain a solid electrolytic capacitor having a small change with time.

  Further, the proportion of the aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof contained in the carbon layer 14a is in the range of 0.06 to 1.25 with respect to 1 carbon particle. It is preferable that the effect of maintaining the adhesion of the carbon layer 14a to the solid electrolyte layer 13 in a high temperature environment is great.

  In the case where the proportion of the aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof contained in the carbon layer 14a is less than 0.06 with respect to 1 in the carbon layer 14a, In a high temperature environment, the effect of maintaining the adhesion of the carbon layer 14a to the solid electrolyte layer 13 cannot be sufficiently obtained, and in the range exceeding 1.25, the specific resistance of the carbon layer 14a becomes large. , ESR increases.

  Among the aromatic sulfonic acid formaldehyde condensates, the phenol sulfonic acid formaldehyde condensate has a particularly large effect of maintaining the adhesion of the carbon layer 14a to the solid electrolyte layer 13 in a high temperature environment, and the ESR over time. A solid electrolytic capacitor with very little change can be obtained.

  Moreover, it is preferable to make the molecular weight of this polystyrene sulfonic acid and its salt into the range of 10,000-1 million, and the effect | action which maintains the adhesive force of the carbon layer 14a to the solid electrolyte layer 13 in a high temperature environment is large.

  In addition, when the molecular weight of polystyrene sulfonic acid and its salt is less than 10,000, the effect of maintaining the adhesion of the carbon layer 14a to the solid electrolyte layer 13 cannot be sufficiently obtained in a high temperature environment, and the range exceeding 1000000. Then, the specific resistance of the carbon layer 14a increases, and the ESR increases.

  In addition, as a method of forming a carbon layer 14a containing at least one of aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof and carbon particles on the solid electrolyte layer 13, an aromatic sulfonic acid is used. A turbid liquid in which at least one of formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof and carbon particles are mixed and turbid is applied on the solid electrolyte layer 13 and then dried, thereby drying the carbon in the turbid liquid. Since the dispersibility of the particles is high, a dense and homogeneous carbon layer 14a can be formed on the surface of the solid electrolyte layer 13, and the adhesion between the solid electrolyte layer 13 and the carbon layer 14a can be enhanced.

  In addition, the dispersibility of the carbon particles in the turbid liquid can be further improved by adding ammonia or the like to the suspension to make it alkaline (pH about 8 to 11).

  In addition, if the content of the carbon particles in the turbid liquid is 2 to 10 wt%, the dispersibility of the carbon particles can be improved.

  The carbon layer 14a contains an aromatic compound represented by the general formula (Chemical Formula 1) in addition to at least one of aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof. By adopting the configuration, the effect of sustaining the adhesion of the carbon layer 14a to the solid electrolyte layer 13 in a high temperature environment can be synergistically increased, and a solid electrolytic capacitor in which the change in ESR with time is further reduced can be obtained. There is an effect that can be.

  In addition, the content ratio of the aromatic compound represented by the general formula (Chemical Formula 1) contained in the carbon layer 14a is in the range of 0.1 to 1.8 with respect to 1 of the carbon particles, so that the high temperature environment Below, the effect | action which maintains the adhesive force of the carbon layer 14a to the solid electrolyte layer 13 becomes large, and the synergistic effect with aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or these salts becomes large.

  If the content of the aromatic compound represented by the general formula (Chemical Formula 1) is less than 0.1, the effect of maintaining the adhesion of the carbon layer 14a to the solid electrolyte layer 13 in a high-temperature environment decreases, and the aromatic Synergistic effects with the aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or salts thereof are not sufficiently obtained, while the content of the aromatic compound represented by the general formula (Chemical Formula 1) exceeds 1.8. In this range, the specific resistance of the carbon layer 14a increases, and the ESR of the solid electrolytic capacitor increases.

  Further, the aromatic compound represented by the general formula (Chemical Formula 1) contained in the carbon layer 14a is optimally either catechol or pyrogallol, and the adhesion of the carbon layer 14a to the solid electrolyte layer 13 in a high temperature environment. Great effect of sustaining power.

  Further, on the solid electrolyte layer 13, a carbon layer 14 a containing an aromatic compound represented by the general formula (Chemical Formula 1) and at least one of aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof. As a method for forming the above, at least one of aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof, the aromatic compound represented by the general formula (Chemical Formula 1), and carbon particles are turbid. Since the turbid liquid is applied on the solid electrolyte layer 13 and dried, the dispersibility of the carbon particles in the turbid liquid is high, so that a dense and homogeneous carbon layer 14a is formed on the surface of the solid electrolyte layer 13, and the solid electrolyte The adhesion between the layer 13 and the carbon layer 14a can be increased.

  Further, in the process of drying the turbid liquid, the drying temperature is represented by the aromatic sulfonic acid formaldehyde condensate contained in the turbid liquid, polystyrene sulfonic acid, their salts, and the general formula (Formula 1). If the temperature is in the vicinity of the melting point of the aromatic compound, the adhesion between the solid electrolyte layer 13 and the carbon layer 14a can be increased, and the interface resistance can be reduced.

  However, since the solid electrolyte layer 13 is made of a conductive polymer such as polypyrrole, when the drying temperature is higher than 215 ° C., the specific resistance of the solid electrolyte layer 13 itself increases. Come.

  In addition, when the drying temperature is lower than 130 ° C., moisture in the turbid liquid cannot be removed, so that sufficient adhesion between the solid electrolyte layer 13 and the carbon layer 14a cannot be obtained.

  For this reason, the aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, their salts, and the aromatic compound represented by the general formula (Formula 1) have a melting point in the range of 130 ° C to 215 ° C. By doing so, the adhesion between the solid electrolyte layer 13 and the carbon layer 14a can be improved, and the interface resistance is reduced, and at the same time, the increase in the specific resistance of the solid electrolyte layer 13 itself is prevented and the ESR of the solid electrolytic capacitor is reduced. can do.

  Here, specific examples of the melting point of 130 ° C. to 215 ° C. or lower include aromatic sulfonic acid formaldehyde condensates and salts thereof, such as naphthalene sulfonic acid formalin condensate, arylphenol sulfonic acid formaldehyde condensate, phenol sulfone. Examples of polystyrene sulfonates such as acid formaldehyde condensate, anthraquinone sulfonic acid formaldehyde condensate, naphthalene sulfonic acid formaldehyde condensate, sodium salts thereof, and the like. Examples of group compounds include catechol and pyrogallol.

  In order to more clearly confirm the change in characteristics of the solid electrolytic capacitor in the first embodiment under a high temperature environment, a high temperature storage test was conducted using the capacitor element of the solid electrolytic capacitor in the first embodiment. Hereinafter, specific Examples 1 to 23 and Comparative Examples 1 to 4 in Embodiment 1 will be described.

  In addition, the concrete material name and content rate which are contained in the carbon layer 4a of Examples 1-11 and Comparative Examples 1-3 are shown together in (Table 1), and Examples 12-23 and Comparative Example 4 are shown. The specific material names and content ratios contained in the carbon layer 4a are collectively shown in (Table 2).

Example 1
An insulating resist material 20 is pasted on the front and back surfaces of the aluminum foil whose surface area has been enlarged by about 125 times by performing an etching process to separate the anode body 11 and the anode lead-out portion 11a, and the effective area of the anode body 11 portion. Was 3.2 mm × 3.9 mm.

  The anode body 11 was immersed in an aqueous solution of ammonium dihydrogen phosphate having a liquid temperature of 70 ° C. and a concentration of 0.3 wt%, and a 12 V DC voltage was applied for 20 minutes to form an anodized film. An oxide film layer 12 was obtained.

  Next, the anode body 11 having the dielectric oxide film layer 12 formed thereon was dipped in a 20 wt% manganese nitrate aqueous solution at 25 ° C. for 3 seconds and then pulled up, and then the excess manganese nitrate aqueous solution attached to the surface was blown off with air. Subsequently, the temperature was raised to 250 ° C. or higher within 1 minute, and thermal decomposition was performed at 300 ° C. for 5 minutes to form a manganese dioxide layer on the dielectric oxide film layer, thereby forming a precoat layer of the solid electrolyte layer 13.

  Then, the solid electrolyte layer 13 of the conductive polymer which consists of a polypyrrole film | membrane was formed on the manganese dioxide layer formed in the anode body 11 by the electrolytic polymerization method.

  Subsequently, the manganese dioxide layer of the anode body 11 in a polymerization solution obtained by mixing 0.5 mol / L of a pyrrole monomer as a polymerizable monomer and 0.1 mol / L of sulfosalicylic acid as a dopant in an organic solvent. A solid electrode made of a conductive polymer is prepared by bringing a polymerization anode electrode close to the surface and applying a voltage so that a potential difference of 3 V is generated on the polymerization cathode electrode provided opposite to the polymerization anode electrode to produce a potential difference of 3 V. An electrolyte layer 13 was formed.

  Next, 5 wt% carbon particles and 0.3 wt% phenolsulfonic acid formaldehyde condensate are turbid, and an aqueous carbon solution is prepared by adding ammonia to pH 10. The solid electrolyte layer 13 is added to the turbid aqueous carbon solution. After the anode body 11 having been formed was dipped, it was pulled up and dried at 215 ° C. to remove the solvent component to form the carbon layer 14a (at this time, the carbon particles were condensed with phenolsulfonic acid formaldehyde with respect to 1 in the carbon layer 14a). The product is contained in a ratio of 0.06 and is uniformly dispersed in the carbon layer 14a).

  Subsequently, a conductive paste made of a silver filler and an epoxy binder resin is applied on the carbon layer 14a, and then cured at 150 to 200 ° C. for 10 to 60 minutes to form a conductor layer 14b. Obtained.

(Example 2)
In the above Example 1, as a method for forming the carbon layer 14a, a carbon aqueous solution in which 5 wt% carbon particles and 2.5 wt% phenolsulfonic acid formaldehyde condensate were turbid and ammonia was added to a pH of 10 was used. Except for the above, a capacitor element 15 was produced in the same manner as in Example 1 (At this time, in the carbon layer 14a, the carbon sulfonated formaldehyde condensate was contained at a ratio of 0.5 to 1 with respect to the carbon particles 14a. Uniformly distributed).

(Example 3)
In Example 1, the carbon layer 14a was formed by using a carbon aqueous solution in which 5 wt% carbon particles and 6.25 wt% phenolsulfonic acid formaldehyde condensate were turbid and ammonia was added to a pH of 10. Except for the above, a capacitor element 15 was produced in the same manner as in Example 1 (At this time, in the carbon layer 14a, the carbon particles were contained at a ratio of 1.25 to 1 for the phenolsulfonic acid formaldehyde condensate and the carbon layer 14a. Uniformly distributed).

Example 4
In Example 1 above, as a method for forming the carbon layer 14a, a carbon aqueous solution in which 5 wt% carbon particles and 0.3 wt% sodium naphthalene sulfonate formalin condensate are turbid and ammonia is added to a pH of 10 is used. The capacitor element 15 was produced in the same manner as in Example 1 except that the carbon layer 14a contained carbon naphthalene sulfonate formalin condensate at a ratio of 0.06 to carbon 1, and the carbon element 14 was Uniformly distributed in the layer 14a).

(Example 5)
In Example 1 above, as a method for forming the carbon layer 14a, a carbon aqueous solution in which 5 wt% carbon particles and 0.3 wt% arylphenol sulfonic acid formaldehyde condensate are turbid and ammonia is added to a pH of 10 is used. The capacitor element 15 was produced in the same manner as in Example 1 except that the carbon layer 14a contained the arylphenol sulfonic acid formaldehyde condensate at a ratio of 0.06 to the carbon layer 14a. Uniformly distributed in the layer 14a).

(Example 6)
In Example 1 above, as a method of forming the carbon layer 14a, a carbon aqueous solution in which 5 wt% carbon particles and 0.3 wt% sodium polystyrene sulfonate (molecular weight: 10,000) are turbid and ammonia is added to a pH of 10. The capacitor element 15 was produced in the same manner as in Example 1 except that the carbon layer 14a contained sodium polystyrene sulfonate at a ratio of 0.06 to 1 in the carbon layer 14a. 14a).

(Example 7)
A capacitor element 15 was produced in the same manner as in Example 6 except that the molecular weight of sodium polystyrene sulfonate was changed to 1,000,000 in Example 6 (At this time, in the carbon layer 14a, the number of polystyrene particles in the carbon layer 14a was 1 for polystyrene sulfonic acid. Sodium is contained in a ratio of 0.06 and is uniformly dispersed in the carbon layer 14a).

(Example 8)
In Example 1 above, as a method of forming the carbon layer 14a, a carbon aqueous solution in which 5 wt% carbon particles and 2.5 wt% sodium polystyrene sulfonate (molecular weight: 20000) are turbid and ammonia is added to a pH of 10. The capacitor element 15 was fabricated in the same manner as in Example 1 except that the carbon layer 14a contained sodium polystyrene sulfonate at a ratio of 0.5 to 1 in the carbon layer 14a. 14a).

Example 9
In Example 1 above, as a method of forming the carbon layer 14a, a carbon aqueous solution in which 5 wt% carbon particles and 6.25 wt% sodium polystyrene sulfonate (molecular weight: 10,000) are turbid and ammonia is added to a pH of 10. A capacitor element 15 was produced in the same manner as in Example 1 except that the carbon layer 14a contained sodium polystyrene sulfonate at a ratio of 1.25 to 1 in the carbon layer 14a. 14a).

(Example 10)
A capacitor element 15 was produced in the same manner as in Example 9 except that the molecular weight of sodium polystyrene sulfonate was changed to 1,000,000 in Example 9 (At this time, in the carbon layer 14a, the carbon particles were 1 in terms of polystyrene sulfonic acid. Sodium is contained at a ratio of 1.25 and is uniformly dispersed in the carbon layer 14a).

(Example 11)
In Example 1 above, as a method of forming the carbon layer 14a, a carbon aqueous solution in which 5 wt% carbon particles and 0.3 wt% polystyrene sulfonic acid (molecular weight: 10,000) are turbid and ammonia is added to a pH of 10 is used. A capacitor element 15 was produced in the same manner as in Example 1 except that it was used. (At this time, in the carbon layer 14a, the carbon particles contained 1 in a ratio of 0.06 to polystyrene sulfonic acid. Evenly distributed).

(Example 12)
In Example 1 above, as a method for forming the carbon layer 14a, 5 wt% carbon particles, 0.3 wt% phenolsulfonic acid formaldehyde condensate, and 0.5 wt% pyrogallol are turbid, and ammonia is added. A capacitor element 15 was produced in the same manner as in Example 1 except that a carbon aqueous solution having a pH of 10 was used (at this time, in the carbon layer 14a, the carbon particle was 1 and the phenolsulfonic acid formaldehyde condensate was 0.06, Pyrogallol is contained at a ratio of 0.1 and is uniformly dispersed in the carbon layer 14a).

(Example 13)
In Example 12, a capacitor element 15 was produced in the same manner as in Example 12 except that the temperature for drying the solid electrolyte layer 13 coated with the carbon aqueous solution by dipping was 130 ° C. (At this time, in the carbon layer 14a) The carbon particles are contained in a proportion of 0.06 for phenolsulfonic acid formaldehyde condensate and 0.1 for pyrogallol, and are uniformly dispersed in the carbon layer 14a).

(Example 14)
In Example 1 above, as a method of forming the carbon layer 14a, 5 wt% carbon particles, 0.3 wt% phenolsulfonic acid formaldehyde condensate, and 5 wt% pyrogallol are turbid, and ammonia is added to a pH of 10 The capacitor element 15 was produced in the same manner as in Example 1 except that the carbon aqueous solution was used (in this case, in the carbon layer 14a, the carbon particle was 1 and the phenolsulfonic acid formaldehyde condensate was 0.06, pyrogallol was 1 and is uniformly dispersed in the carbon layer 14a).

(Example 15)
In Example 1 described above, as a method of forming the carbon layer 14a, 5 wt% carbon particles, 0.3 wt% phenolsulfonic acid formaldehyde condensate, and 9 wt% pyrogallol are turbid, and ammonia is added to adjust the pH to 10. The capacitor element 15 was produced in the same manner as in Example 1 except that the carbon aqueous solution was used (in this case, in the carbon layer 14a, the carbon particle was 1 and the phenolsulfonic acid formaldehyde condensate was 0.06, pyrogallol was 1.8 and contained uniformly in the carbon layer 14a).

(Example 16)
In Example 1 above, as a method of forming the carbon layer 14a, 5 wt% carbon particles, 0.3 wt% sodium naphthalene sulfonate formalin condensate, and 0.5 wt% pyrogallol are turbid, and ammonia is added. A capacitor element 15 was produced in the same manner as in Example 1 except that a carbon aqueous solution having a pH of 10 was used (at this time, in the carbon layer 14a, the carbon particle was 1 and the sodium naphthalenesulfonate formalin condensate was 0.1. 06, pyrogallol is contained at a ratio of 0.1 and is uniformly dispersed in the carbon layer 14a).

(Example 17)
In Example 1 above, as a method of forming the carbon layer 14a, 5 wt% carbon particles, 0.3 wt% arylphenol sulfonic acid formaldehyde condensate, and 0.5 wt% pyrogallol are turbid, and ammonia is added. A capacitor element 15 was produced in the same manner as in Example 1 except that a carbon aqueous solution adjusted to pH 10 was used (at this time, in the carbon layer 14a, the carbon particles were 1 and the arylphenol sulfonic acid formaldehyde condensate was 0.1. 06, pyrogallol is contained at a ratio of 0.1 and is uniformly dispersed in the carbon layer 14a).

(Example 18)
In Example 1 above, as a method for forming the carbon layer 14a, 5 wt% carbon particles, 0.3 wt% sodium polystyrene sulfonate (molecular weight: 10,000), and 0.5 wt% pyrogallol are turbid, and ammonia is added. A capacitor element 15 was produced in the same manner as in Example 1 except that a carbon aqueous solution having a pH of 10 was added (at this time, in the carbon layer 14a, the carbon particle was 1 and the polystyrene sodium sulfonate was 0.06). Pyrogallol is contained at a ratio of 0.1 and is uniformly dispersed in the carbon layer 14a).

(Example 19)
In Example 18, except that the molecular weight of sodium polystyrene sulfonate was changed to 1,000,000, a capacitor element 15 was produced in the same manner as in Example 18 (At this time, in the carbon layer 14a, the carbon particles had a polystyrene sulfonic acid ratio to 1. Sodium is contained in a ratio of 0.06 and pyrogallol is contained in a ratio of 0.1 and is uniformly dispersed in the carbon layer 14a).

(Example 20)
In Example 1 above, as a method for forming the carbon layer 14a, 5 wt% carbon particles, 0.3 wt% sodium polystyrene sulfonate (molecular weight: 20000), and 5 wt% pyrogallol are turbid, and ammonia is added. A capacitor element 15 was produced in the same manner as in Example 1 except that a carbon aqueous solution having a pH of 10 was used (at this time, in the carbon layer 14a, the carbon particles were 1 and the polystyrene sulfonate sodium was 0.06, pyrogallol). Is contained in a ratio of 1 and is uniformly dispersed in the carbon layer 14a).

(Example 21)
In Example 1 above, as a method for forming the carbon layer 14a, 5 wt% carbon particles, 0.3 wt% sodium polystyrene sulfonate (molecular weight: 10,000), and 9 wt% pyrogallol are turbid, and ammonia is added. A capacitor element 15 was produced in the same manner as in Example 1 except that a carbon aqueous solution having a pH of 10 was used (at this time, in the carbon layer 14a, the carbon particles were 1 and the polystyrene sulfonate sodium was 0.06, pyrogallol). Is contained in a ratio of 1.8 and is uniformly dispersed in the carbon layer 14a).

(Example 22)
A capacitor element 15 was produced in the same manner as in Example 21 except that the molecular weight of sodium polystyrene sulfonate was changed to 1,000,000 in Example 21 (at this time, in the carbon layer 14a, the carbon particles were 1 in terms of polystyrene sulfonic acid. Sodium is contained in a ratio of 0.06 and pyrogallol is contained in a ratio of 1.8 and is uniformly dispersed in the carbon layer 14a).

(Example 23)
In Example 1 above, as a method for forming the carbon layer 14a, 5 wt% carbon particles, 0.3 wt% sodium polystyrene sulfonate (molecular weight: 10,000), and 0.5 wt% pyrogallol are turbid, and ammonia is added. A capacitor element 15 was produced in the same manner as in Example 1 except that a carbon aqueous solution having a pH of 10 was added (at this time, in the carbon layer 14a, the carbon particle was 1 and the polystyrene sodium sulfonate was 0.06). Pyrogallol is contained at a ratio of 0.1 and is uniformly dispersed in the carbon layer 14a).

(Comparative Example 1)
In Example 1 described above, as a method for forming the carbon layer 14a, 5 wt% carbon particles and 0.3 wt% polyethylene glycol lauryl ether (8 mol of ethylene oxide added) were turbid and ammonia was added to a pH of 10 A capacitor element 15 was produced in the same manner as in Example 1 except that the carbon aqueous solution was used (at this time, the carbon layer 14a contained 0.06 of polyethylene glycol lauryl ether with respect to 1 carbon particle. And uniformly dispersed in the carbon layer 14a).

(Comparative Example 2)
In Example 1, the carbon layer 14a is formed by using a carbon aqueous solution in which 5 wt% carbon particles and 0.3 wt% sodium branched dodecylbenzenesulfonate are turbid and ammonia is added to a pH of 10. The capacitor element 15 was produced in the same manner as in Example 1 except that the carbon layer 14a contained 0.06 of sodium branched alkylbenzene sulfonate with respect to 1 carbon particle and 1% of the carbon layer 14a. Uniformly distributed).

(Comparative Example 3)
In Example 1, the capacitor element 15 was produced in the same manner as in Example 1 except that a carbon aqueous solution in which 5 wt% of carbon particles were suspended and ammonia was added to adjust the pH to 10 was used as a method for forming the carbon layer 14a. did.

(Comparative Example 4)
In Example 1 above, the carbon layer 14a was formed by using a carbon aqueous solution in which 5 wt% carbon particles and 0.5 wt% pyrogallol were turbid and ammonia was added to a pH of 10. The capacitor element 15 was produced in the same manner as in No. 1 (At this time, in the carbon layer 14a, pyrogallol was contained in a ratio of 0.1 with respect to 1 of carbon particles, and was uniformly dispersed in the carbon layer 14a).

  Initial characteristics (capacitance C, ESR) of capacitor elements 15 of Examples 1 to 23 of the first embodiment and Comparative Examples 1 to 4 manufactured as described above, and when left at 125 ° C. for 500 hours The capacity change rate (ΔC) and the ESR change rate (ΔESR) are shown in Table 3.

  Also, the anode terminal 16 is welded to the anode lead portion 11a of the capacitor element 15 of each sample, and the cathode terminal 18 is connected to the conductor layer 14b using a conductive adhesive. Thereafter, the capacitor element 15 is covered with an insulating exterior resin 19 so that the connection portions 16a and 18a of the anode terminal 16 and the cathode terminal 18 are exposed. Thus, the solid electrolytic capacitor of each sample is produced. The dimensions of this solid electrolytic capacitor are 7.3 × 4.3 × 2.8 mm, and the rated values are 4.0 WV and 47 μF.

  The solid electrolytic capacitors of the samples thus prepared were evaluated in the same manner as the capacitor element 15 described above. The results are also shown in (Table 3).

  The measurement was performed at a temperature of 25 to 30 ° C., the capacitance was measured at 120 Hz, the ESR was measured at 100 kHz, and an average value of n = 30 was shown.

  As is clear from this (Table 3), the capacitor elements of Examples 1 to 11 have a structure in which the carbon layer 14a contains an aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof. From Comparative Examples 1 and 2 (Comparative Example 1: Containing polyethylene glycol lauryl ether, Comparative Example 2: Containing branched sodium dodecylbenzenesulfonate), ΔESR is decreased when left at 125 ° C. for 500 hours. be able to.

  In addition, the capacitor elements of Examples 1 to 3 were obtained by changing the content ratio of the phenolsulfonic acid formaldehyde condensate with respect to the carbon particles in the carbon layer 14a. By setting the carbon particles in the range of 0.06 to 1.25 with respect to 1, the post-high temperature environmental load characteristics with less ESR change can be reliably obtained.

  Further, as the aromatic sulfonic acid formaldehyde condensate contained in the carbon layer 14a, in particular, Example 1 using a phenol sulfonic acid formaldehyde condensate is different from Examples 4 and 5 using other aromatic sulfonic acid formaldehyde condensates. In comparison, it is possible to obtain excellent post-high temperature environmental load characteristics, particularly with little ESR change.

  In the capacitor elements of Examples 6 to 11, in the carbon layer 14a, the content ratio of sodium polystyrene sulfonate to the carbon particles was changed. On the other hand, by setting it to 0.06 to 1.25, it is possible to reliably obtain the high temperature environmental load post-change characteristic with less ESR change.

  Moreover, although the capacitor elements of Examples 6 to 11 are obtained by changing the molecular weight of sodium polystyrene sulfonate contained in the carbon layer 14a, the molecular weight of this sodium polystyrene sulfonate is in the range of 10,000 to 1,000,000. Thus, it is possible to reliably obtain the post-high temperature environmental load characteristics with less ESR change.

  In addition, the capacitor element of Comparative Example 4 has a configuration in which pyrogallol, which is an aromatic compound represented by the general formula (Chemical Formula 1), is contained in the carbon layer 14a. Thus, it is possible to improve the initial characteristics of the capacitances C and ESR, and to obtain an effect of reducing ΔESR after being left at 125 ° C. for 500 hours.

  On the other hand, the capacitor elements shown in Examples 12 to 23 contain at least one or more of aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof in carbon layer 14a, and further contain pyrogallol. Thus, it is possible to synergistically enhance the effect of maintaining the adhesion between the solid electrolyte layer 13 and the carbon layer 14a in a high temperature environment. As a result, ΔESR after standing at 125 ° C. for 500 hours is more than in the case where the carbon layer 14a contains aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof, and pyrogallol separately. It can be effectively reduced.

  In the capacitor elements of Examples 12 to 23, the content ratio of pyrogallol relative to the carbon particles in the carbon layer 14a was changed. By setting it in the range of -1.8, excellent post-high temperature environmental load characteristics with particularly little ESR change can be obtained with certainty.

  Further, in the capacitor elements of Examples 12 and 13, when the carbon layer 14a was formed, the temperature at which the solid electrolyte layer 13 coated with the carbon aqueous solution was immersed was changed. By setting the temperature within the range of 130 ° C. to 215 ° C., it is possible to reliably obtain high temperature environmental load characteristics with less ESR change.

  In addition, the evaluation result of the solid electrolytic capacitor shows the same tendency as the evaluation result of the capacitor element.

  In the solid electrolytic capacitor of the present invention, the carbon layer contains at least one or more of aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof. Since the adhesion of the carbon layer is maintained, peeling of the carbon layer can be suppressed. As a result, it is possible to prevent an increase in the interface resistance between the solid electrolyte layer and the carbon layer, and to prevent an increase in the specific resistance of the solid electrolyte layer itself by suppressing the intrusion of external oxygen, so that the change in ESR over time is small. It can be used as a solid electrolytic capacitor and is useful for various electronic devices.

DESCRIPTION OF SYMBOLS 11 Anode body 11a Anode lead-out part 12 Dielectric oxide film layer 13 Solid electrolyte layer 14 Cathode layer 14a Carbon layer 14b Conductor layer 15 Capacitor element 16 Anode terminal 16a Connection part 17 Conductive adhesive 18 Cathode terminal 18a Connection part 19 Exterior resin 20 resist material

Claims (9)

An anode body made of a valve metal, a dielectric oxide film layer formed on the surface of the anode body, a solid electrolyte layer containing a dopant formed on the surface of the dielectric oxide film layer, and the solid electrolyte layer In a solid electrolytic capacitor having a capacitor element composed of a carbon layer and a conductor layer sequentially formed as a cathode layer on the surface of
The carbon layer contains at least one or more additives selected from aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or salts thereof, and the additive is a solid electrolytic capacitor having a configuration different from that of the dopant. The ratio in which at least one of the aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof is contained in the carbon layer is in the range of 0.06 to 1.25 per 1 carbon particle. Item 10. A solid electrolytic capacitor according to Item 1. The solid electrolytic capacitor according to claim 1 or 2, wherein a molecular weight of the polystyrene sulfonic acid and a salt thereof is in a range of 10,000 to 1,000,000. The aromatic sulfonic acid formaldehyde condensate is naphthalene sulfonic acid formalin condensate, arylphenol sulfonic acid formaldehyde condensate, phenol sulfonic acid formaldehyde condensate, anthraquinone sulfonic acid formaldehyde condensate, naphthalene sulfonic acid formaldehyde condensate, or a salt thereof. The solid electrolytic capacitor according to claim 1, which is at least one of the following. The solid electrolytic capacitor according to claim 1, wherein the polystyrene sulfonate salt is sodium polystyrene sulfonate. 2. The solid according to claim 1, wherein the carbon layer contains at least one of aromatic sulfonic acid formaldehyde condensate, polystyrene sulfonic acid, or a salt thereof and an aromatic compound represented by the general formula (Formula 1). Electrolytic capacitor.

The solid electrolysis according to claim 6, wherein the ratio of the aromatic compound represented by the general formula (Formula 1) contained in the carbon layer is in the range of 0.1 to 1.8 with respect to 1 of the carbon particles. Capacitor. The solid electrolytic capacitor according to claim 6 or 7, wherein the aromatic compound represented by the general formula (Formula 1) is at least one of catechol and pyrogallol. The melting point of the aromatic sulfonate formaldehyde condensate, polystyrene sulfonic acid, a salt thereof, and the aromatic compound represented by the general formula (Chemical Formula 1) is in a range of 130 ° C to 215 ° C. 6. The solid electrolytic capacitor according to 6.

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