JP2007103468A - Electrolytic capacitor and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an electrolytic capacitor for forming an electrolyte layer with a uniform thickness by a simple method. <P>SOLUTION: The electrolytic capacitor comprises a valve metal substrate; a dielectric layer formed on the valve metal substrate; a solid electrolyte layer formed on the dielectric layer; and a conductive layer formed on the solid electrolyte layer. Then, the electrolyte layer in the electrolytic capacitor contains 150-1,000 ppm iron. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrolytic capacitor and a manufacturing method thereof.

  A solid electrolytic capacitor (hereinafter abbreviated as “electrolytic capacitor”) is generally a valve metal base made of a metal having a so-called valve action such as aluminum or tantalum, and a dielectric layer made of an oxide film obtained by oxidizing this surface. In addition, an electrolyte layer made of a polymer electrolyte and a conductor layer made of graphite, silver or the like are sequentially laminated. Such an electrolytic capacitor is characterized by a relatively large capacity among various capacitors.

  The electrolyte layer in an electrolytic capacitor is generally formed by polymerizing a monomer component on a dielectric layer of a valve metal substrate to produce a polymer electrolyte. As this polymerization method, chemical oxidative polymerization capable of producing a polymer electrolyte simply by attaching a polymerization solution containing an oxidizing agent and a monomer to the surface of the dielectric layer is employed.

Conventionally, many iron salts have been used as the oxidizing agent used in the polymerization solution. However, the iron salt used as the oxidizing agent remains in the solid electrolyte layer as divalent or trivalent iron ions after the oxidative polymerization, and easily causes an increase in leakage current of the electrolytic capacitor or occurrence of a short circuit. Therefore, in order to eliminate such inconvenience, an electrolytic capacitor in which the iron concentration in the fixed electrolyte layer is maintained at a low level of 100 ppm or less has been proposed.
JP 2001-167981 A

  By the way, capacitors are mounted on a wide range of electronic devices, and many of these electronic devices are expected to be used under high temperature conditions such as in-vehicle computers. Conventionally, as a capacitor used under such a high temperature condition, a capacitor having relatively high heat resistance such as a ceramic capacitor has been applied. However, in recent years, further increase in capacity has been demanded for these capacitors, and application of electrolytic capacitors is desired.

  However, since electrolytic capacitors contain polymer electrolytes, they have lower heat resistance compared to ceramic capacitors and the like, and when exposed to high temperature conditions, for example, the capacity is gradually reduced. It was. Although the above-mentioned conventional electrolytic capacitor can greatly reduce the disadvantages such as increase of leakage current and occurrence of short circuit, it maintains the capacitor characteristics well under high temperature conditions as well as the conventional one. Tended to be difficult.

  Then, this invention is made | formed in view of the said situation, and it aims at providing the electrolytic capacitor which has the outstanding heat resistance, and its manufacturing method.

  In order to achieve the above object, the present inventors have conducted intensive research. As a result, the amount of iron contained in the electrolyte layer is not minimized as in the above-described prior art, but the electrolyte layer has a certain concentration or more. The inventors have found new knowledge that the heat resistance of electrolytic capacitors can be improved by including iron, and have completed the present invention.

  That is, the electrolytic capacitor of the present invention includes a valve metal substrate, a dielectric layer formed on the valve metal substrate, a solid electrolyte layer formed on the dielectric layer and containing 150 to 1000 ppm of iron, and a solid electrolyte layer And a conductor layer formed thereon.

  Since the electrolytic capacitor of the present invention contains a large amount of iron as compared with the conventional electrolytic capacitor of 150 ppm or more in the electrolyte layer, the deterioration of the capacitor characteristics is small even when exposed to high temperature conditions, and is excellent. It has high heat resistance. Although this factor is not necessarily clear, for example, iron contained in a divalent or trivalent state in the electrolyte layer captures components that react with the solid electrolyte under high temperature conditions to cause deterioration of the electrolyte layer. Part of this is expected to play a role. However, the action is not limited to this.

  The method for producing an electrolytic capacitor according to the present invention is a method by which the electrolytic capacitor according to the present invention can be suitably produced. The element body includes a valve metal substrate and a dielectric layer formed on the valve metal substrate. Preparing a polymer electrolyte containing an iron salt and a monomer on at least the surface of the dielectric layer of the element body, polymerizing the monomer in the polymerization liquid, and forming a solid electrolyte layer on the dielectric layer And forming a solid electrolyte layer, wherein 150 to 1000 ppm of iron derived from an iron salt is left in the solid electrolyte layer.

  In this method, an iron capacitor is used as an oxidizing agent, and iron derived from the iron salt is left in the electrolyte layer, whereby an electrolytic capacitor including an electrolyte layer containing iron can be easily manufactured. The electrolytic capacitor thus obtained can exhibit excellent heat resistance because the electrolyte layer contains iron as described above.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the electrolytic capacitor which has the outstanding heat resistance, and its manufacturing method.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Throughout the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Also, the positional relationships such as up, down, left, and right in the description are all based on the positional relationships in the drawings.

  First, the structure of an electrolytic capacitor obtained by a manufacturing method according to a preferred embodiment will be described with reference to FIG. FIG. 1 is a diagram schematically showing a cross-sectional structure of an electrolytic capacitor obtained by a manufacturing method according to a preferred embodiment.

  The electrolytic capacitor 10 includes a valve metal base 12 having an anode portion 12a and a cathode portion 12b, a dielectric layer 14, an electrolyte layer 15 and a cathode layer 16 formed in this order on the surface of the cathode portion 12b in the valve metal base 12. It is composed of On the surface of the valve metal base 12, a resist portion 19 is formed at the boundary between the anode portion 12a and the cathode portion 12b.

  The valve metal substrate 12 functions as an anode in the electrolytic capacitor 10 and has a foil shape or a thin plate shape. A part of the valve metal substrate 12 is drawn from the laminated structure formed on the surface thereof, which includes the dielectric layer 14, the electrolyte layer 15, and the cathode layer 16, and this portion corresponds to the anode portion 12a.

  The valve metal base 12 is made of a metal having a valve action. Examples of such a metal include aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony. Of these, aluminum or tantalum is preferable. Although not shown, the valve metal base 12 has at least the surface of the cathode portion 12b roughened to have fine irregularities, and the surface area is thereby expanded. Moreover, the resist part 19 is comprised from the resin material which has insulation, such as an epoxy resin and a silicone resin.

  The dielectric layer 14 has an extremely thin layered structure provided along the surface of the valve metal substrate 12, more specifically along the fine uneven surface of the cathode portion 12b. The dielectric layer 14 is composed of an oxide film formed by oxidizing the surface of the valve metal base 12.

  The electrolyte layer 15 substantially functions as a cathode in the electrolytic capacitor, and is composed of a polymer electrolyte made of a conductive polymer. The conductive polymer is not particularly limited as long as it can be synthesized by chemical oxidative polymerization, and examples thereof include polythiophene and polypyrrole.

  The electrolyte layer 15 contains 150 to 1000 ppm of iron. This iron is contained, for example, in the form of a divalent or trivalent iron salt. Examples of such an iron salt include a residue of an oxidant used for chemical oxidative polymerization when the electrolyte layer 15 is formed, and a by-product after the reaction of the oxidant. Specifically, for example, when a trivalent iron salt is used as the oxidant, the trivalent iron salt as the iron salt and the divalent iron salt after the reaction are mainly contained in the electrolyte layer 15. included. These suitable iron salts will be described later.

  The iron concentration (ppm) in the electrolyte layer 15 is a value based on mass, and is calculated from the mass of iron with respect to the total mass of the electrolyte layer 15. Such iron concentration can be measured by LA-ICP-MS. That is, it can be measured by irradiating the electrolyte layer with laser and quantifying the heat evaporated by ICP-MS (Inductively Coupled Plasma Mass Spectrometer).

  When the concentration of iron in the electrolyte layer 15 is less than 150 ppm, the electrolyte layer 15 easily deteriorates when exposed to high temperatures, and as a result, the heat resistance of the electrolytic capacitor 10 becomes insufficient. On the other hand, when the concentration of iron exceeds 1000 ppm, for example, the iron salt contained in the electrolyte layer 15 adheres to a defect portion or the like of the dielectric layer 14 and becomes conductive, so that the electrolytic capacitor 10 However, inconveniences such as increase in leakage current and occurrence of short circuit are likely to occur. From the viewpoint of more reliably reducing these disadvantages, the concentration of iron in the electrolyte layer 15 is 150 to 1000 ppm, preferably 200 to 800 ppm.

  In addition, the electrolyte layer 15 does not need to contain iron uniformly. For example, the electrolyte layer 15 may have an iron concentration gradient in the thickness direction as long as the entire layer has the above-described iron concentration range. Good. Here, as the iron concentration “as the entire electrolyte layer 15”, for example, an average value of values measured at a plurality of locations in the thickness direction of the electrolyte layer 15 can be adopted. From the viewpoint of obtaining excellent heat resistance and sufficiently reducing the occurrence of leakage current and short circuit, the electrolyte layer 15 has a high iron content on the side close to the dielectric layer 14 and is close to the cathode layer 16. It is preferable to have a concentration gradient such that the iron content on the side is small. In order to easily obtain such a structure, for example, the electrolyte layer 15 may have a multilayer structure including a layer having a high iron concentration and a layer having a low iron concentration or no iron.

  The cathode 16 (conductor layer) is made of a conductor and functions as a cathode together with the electrolyte layer 15. Although it does not restrict | limit especially as the cathode 16, For example, the thing of the 2 layer structure by which the carbon layer 17 and the silver layer 18 were laminated | stacked in order from the electrolyte layer 15 side can be illustrated.

  Next, a preferred embodiment of a method for manufacturing the electrolytic capacitor 10 having the above-described structure will be described.

  In the production of the electrolytic capacitor 10, first, a valve metal base 12 made of a metal foil composed of a metal having a valve action as described above is prepared. Next, this valve metal substrate 12 is subjected to chemical or electrochemical etching to form a large number of fine irregularities on the surface (roughening). Then, anodization or the like is performed on the surface of the valve metal base 12 on which the irregularities are formed, and an oxide film is formed on the surface. In the case where a sufficient oxide film can be formed in the dielectric layer 14 forming step described later, the step of forming this oxide film is not necessarily required.

  Next, a resist portion 19 is formed on both surfaces of the foil-like valve metal base 12 to partition the valve metal base 12 into an anode portion 12a and a cathode portion 12b. For example, the resist portion 19 is formed by transferring or screen-printing a liquid resin such as an epoxy resin or a silicone resin on the surface of the valve metal base 12, or using a resist material previously formed into a tape shape as the valve metal base 12. It can form by the method of affixing on the desired position. From the viewpoint of simply forming the resist portion 19, the former method by transfer or screen printing is preferred.

  Then, the surface of the cathode portion 12b in the valve metal base 12 is oxidized by anodic oxidation or the like, and a dielectric layer 14 made of an oxide film is formed on the surface of the region. In the formation of the dielectric layer 14, at least the cathode portion 12b of the valve metal substrate 12 is immersed in the chemical conversion solution, and anodic oxidation is caused by applying a voltage with the valve metal substrate 12 as the anode side. When the oxide film is previously formed by the anodic oxidation as described above, an oxide film is further formed on the unformed part or damaged part of the oxide film (reforming). The oxide film thus obtained has excellent insulating properties and can function effectively as the dielectric layer 14 in the electrolytic capacitor 10.

  Examples of chemical conversion solutions suitable for anodization include buffer solutions such as ammonium borate, ammonium phosphate, and organic acid ammonium. Of these, an aqueous solution of ammonium adipate which is an organic acid ammonium is preferable.

  As described above, when an oxide film is formed on the valve metal base 12 before re-forming, or when a chemical conversion solution adheres to the anode part 12a during re-forming, the oxide film is formed on the surface of the anode part 12a. Will exist. In this case, the anode portion 12a is secured to the other terminal to which the anode portion 12a is connected by removing the oxide film in a subsequent process or joining the anode portion 12a by welding.

  After that, a polymer solution containing an iron salt as an oxidizing agent and a monomer that becomes a polymer electrolyte constituting the electrolyte layer 15 by polymerization is attached on the surface of the dielectric layer 14, and then heat treatment is performed. To cause polymerization of the monomer contained in the polymerization solution. As a result, an electrolyte layer 15 mainly made of a polymer of the monomer is formed on the surface of the dielectric layer 14. The polymerization of such monomers is chemical oxidative polymerization, and this reaction is promoted by an iron salt that is an oxidizing agent contained in the polymerization solution. In order to obtain a desired thickness of the electrolyte layer 15, it is preferable to repeatedly perform the process of attaching the polymerization solution and the polymerization process a plurality of times.

  As an iron salt which is an oxidizing agent contained in the polymerization liquid, for example, a trivalent iron salt is suitable, and examples thereof include iron paratoluenesulfonate, iron dodecylbenzenesulfonate, and iron naphthalenesulfonate. Of these, iron paratoluenesulfonate is preferable. Moreover, as a monomer, the monomer which can become a conductive polymer as mentioned above by superposition | polymerization, for example, a thiophene type compound, a pyrrole type compound, etc. are mentioned.

  Furthermore, the polymerization liquid may further contain a solvent for uniformly dispersing the monomer, the oxidizing agent, and the like. Examples of such a solvent include ethanol, butanol, water, or a mixed solvent thereof. The polymerization solution may further contain a doping material for imparting conductivity to the polymer layer. Examples of the doping material include aromatic sulfonic acids such as paratoluenesulfonic acid and alkylnaphthalenesulfonic acid, inorganic sulfonic acids, and the like.

  Examples of the method of attaching the polymerization solution to the surface of the dielectric layer 14 include a method of immersing the region of the valve metal substrate 12 where the dielectric layer 14 is formed in the polymerization solution. Specifically, the valve metal base 12 is put into the polymerization liquid from the dielectric layer 14 side and immersed until the liquid level of the polymerization liquid and the height of the resist portion 19 coincide with each other, whereby the cathode portion in the valve metal base 12 is obtained. The electrolyte layer 15 can be reliably formed on the region 12b. At this time, the resist portion 19 sufficiently prevents the polymerization liquid from adhering to the anode portion 12a due to a capillary phenomenon or the like.

  In the step of forming the electrolyte layer 15 in this manner, 150 to 1000 ppm of iron derived from the iron salt used as the oxidizing agent is left in the obtained electrolyte layer 15. Examples of the iron derived from the iron salt include iron in the iron salt remaining after the reaction and by-products containing iron generated by the reaction of the iron salt in chemical oxidative polymerization. As the by-product containing iron, for example, a divalent iron salt produced by reacting a trivalent iron salt can be exemplified.

  Examples of the method for setting the iron concentration in the electrolyte layer 15 in the above range include a method in which the washing performed on the polymerized layer is adjusted as desired after the above-described polymerization liquid is attached and polymerized. The electrolyte layer 15 formed by chemical oxidative polymerization usually has a too high concentration of iron derived from an iron salt as an oxidizing agent as it is, and thus tends to cause an increase in leakage current and occurrence of a short circuit as described above. In this case, after the polymerization solution is attached and polymerized, the obtained layer is washed with a predetermined washing solution to remove the iron salt remaining in the layer, and thereby in the electrolyte layer 15. Iron concentration can be reduced. Therefore, if an appropriate amount of iron salt remains in the layer after polymerization by adjusting the amount of iron salt to be removed at the time of washing, the iron concentration is equal to or more than the preferable lower limit value described above. The electrolyte layer 15 can be obtained. Examples of the cleaning liquid used for cleaning the electrolyte layer 15 include a liquid that can be removed by dissolving the iron salt. For example, water is preferable.

  The adjustment of the cleaning can be performed, for example, by changing conditions such as the flow rate of the cleaning liquid and the cleaning time. These are appropriately set according to the concentration of the iron salt in the polymerization solution, the ease of removal of the iron salt, and the like. Besides the methods for changing these cleaning conditions, the following iron concentration adjustment methods are also suitable.

  For example, as described above, when the series of steps of adhesion and polymerization of the polymerization liquid is repeatedly performed in the formation of the electrolyte layer 15, a method of reducing the number of times of cleaning with respect to the number of times of the series of steps is mentioned. It is done. That is, when the iron concentration in the electrolyte layer 15 is reduced as much as conventional, it is normal to perform sufficient washing every time the polymerization solution is attached and polymerized. On the other hand, in this embodiment, there are provided a cleaning time and a non-cleaning time after a series of steps of adhesion and polymerization of the polymerization solution, and a certain amount of iron remains in the electrolyte layer 15 obtained thereby. . The iron concentration can be adjusted to the desired range as described above by increasing or decreasing the number of times of washing with respect to the number of series of steps of adhesion and polymerization of the polymerization solution. In this case, since the iron concentration can be adjusted only by adjusting the number of times of cleaning without strictly controlling the conditions in each cleaning, the electrolytic capacitor 10 of the present embodiment can be easily manufactured. It becomes possible.

  Here, as described above, the electrolyte layer 15 may have a concentration gradient of iron in the thickness direction, and in particular, the iron concentration on the side close to the dielectric layer 14 is high and the side close to the cathode layer 16 is close. It is preferable that the iron concentration is low. In order to realize such a concentration gradient, it is effective to adjust the iron concentration by adjusting the number of times of washing as described above. That is, specifically, in the case where a series of steps of adhesion and polymerization of the polymerization solution is repeated a plurality of times, it is preferable not to perform cleaning after at least the first step and to perform cleaning after at least the last step. Furthermore, when a series of steps of adhesion and polymerization is repeated a plurality of times, it is more preferable to perform washing in the second and subsequent steps.

  In the production of the electrolytic capacitor 10, after the electrolyte layer 15 is formed as described above, the carbon layer 17 and the silver layer 18 are sequentially laminated on the electrolyte layer 15 to form the cathode 16 composed of these. Thus, the electrolytic capacitor 10 having the structure shown in FIG. 1 is obtained. The carbon layer 17 and the silver layer 18 can be formed by using a paste for forming each layer and performing a screen printing method, a dipping method (dip method), a spray coating method, or the like on the electrolyte layer 15. it can.

  The electrolytic capacitor 10 obtained in this way is used alone or in a plurality of layers and mounted on a substrate or connected to a lead electrode or the like, and is practically used as a capacitor element. The electrolytic capacitor 10 or the laminate thereof may be molded by a known method such as casting mold, injection, transfer mold, etc. from the viewpoint of these protections.

  As mentioned above, although the manufacturing method of the electrolytic capacitor which concerns on preferred embodiment, and the electrolytic capacitor obtained by this were demonstrated, this invention is not necessarily limited to these embodiment, In the range which does not deviate from the summary, it is appropriate. Changes can be made.

  For example, the valve metal substrate 12 is not limited to the above-described foil shape, and for example, a block shape can be applied. In this case, the obtained electrolytic capacitor also has a block-like structure as a whole. In addition, the electrolytic capacitor does not have a shape in which the dielectric layer 14, the electrolyte layer 15, and the cathode 16 are formed around the valve metal base 12 as described above, but each of the above layers on one surface of the valve metal base 12. May be laminated, or a plurality of these may be laminated.

  Further, in the above production method, washing with a washing liquid is performed after a series of steps of adhesion and polymerization of the polymerization liquid. For example, when a desired iron concentration is obtained as it is after the series of steps, the above washing is performed. It is not always necessary.

  Furthermore, in the above description, the method of manufacturing the electrolytic capacitors 10 one by one has been described. However, the present invention is not limited to this. For example, the valve metal sheet having a structure in which a plurality of valve metal bases 12 are connected is used. A plurality of electrolytic capacitors 10 may be manufactured at a time by collectively performing the above-described processes on the metal substrate 12.

EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples.
[Manufacture of electrolytic capacitors]

Example 1
First, an aluminum foil (3.5 mm × 6.5 mm) that had been subjected to surface enlargement treatment was prepared as a valve metal substrate. A linear resist was formed on both sides of the aluminum foil so as to be parallel to the short side of the aluminum foil, thereby dividing the aluminum foil into an anode part and a cathode part. The cathode part of this aluminum foil was immersed in an aqueous solution of ammonium adipate that is a chemical conversion solution. Thereafter, an anode terminal was connected to the aluminum foil, and a voltage of 6 V was applied to cause anodic oxidation, thereby forming a dielectric layer made of an aluminum oxide film on the surface of the aluminum foil.

  Subsequently, as a polymerization solution, a mixed solution of 0.9 g of 3,4-ethylenedioxythiophene (BAYTRON M, manufactured by Bayel) and 10.81 g of iron paratoluenesulfonate (BAYTRON C-B 50, manufactured by Bayel) Was prepared. After immersing the cathode part of the aluminum foil in this polymerization solution and pulling it up, a series of steps of heat treatment for about 5 minutes in a furnace at a temperature of 150 ° C. was repeated three times. At this time, after the second series of the above-mentioned series of processes, a process of washing and drying the portion where the polymerization solution adhered after the series of processes was performed each time, and this process was not performed in the first process.

  Thereafter, on the surface of the electrolyte layer, a carbon paste is applied to a thickness of 3 μm to form a carbon layer, and then a silver paste is applied to a thickness of 20 μm to form a silver layer. The cathode comprised from was formed. Thus, an electrolytic capacitor was obtained in which a dielectric layer made of aluminum oxide, an electrolyte layer, and a cathode were laminated in this order on the surface of a valve metal substrate (anode) made of aluminum foil.

  Then, after connecting an anode lead and a cathode lead to the anode and cathode of the obtained capacitor element, the periphery of the capacitor element was covered with an epoxy resin so that these leads were exposed to the outside, thereby obtaining an electrolytic capacitor.

  When manufacturing the electrolytic capacitor of Example 1 described above, the iron concentration in the electrolyte layer after the formation of the electrolyte layer was measured by LA-ICP-MS, and the area that was not washed with water was 900 ppm on a mass basis, The area washed with water was 100 ppm on a mass basis, and the entire electrolyte layer was 350 ppm.

(Example 2)
When repeating a series of steps of immersion in the polymerization solution, pulling up and heat treatment at 150 ° C. for about 5 minutes three times, the procedure was the same as in Example 1 except that the washing was not performed once after the series of steps. Thus, an electrolytic capacitor was obtained.

  When the iron concentration in the electrolyte layer in the obtained electrolytic capacitor was measured in the same manner as in Example 1, the entire electrolyte layer was 800 ppm on a mass basis.

(Comparative Example 1)
The electrolytic capacitor was the same as in Example 1 except that when the series of steps of immersion in the polymerization solution, pulling up, and heat treatment at 150 ° C. for about 5 minutes was repeated three times, washing was performed after each step. Got.

When the iron concentration in the electrolyte layer in the obtained electrolytic capacitor was measured in the same manner as in Example 1, the entire electrolyte layer was 100 ppm on a mass basis.
[Measurement of capacitance and ESR over time under high temperature conditions]

  The electrolytic capacitors of Examples 1-2 and Comparative Example 1 were held at 125 ° C. for 1000 hours. At this time, the capacitance and equivalent series resistance (ESR) of each electrolytic capacitor were measured every time a certain time passed, and the capacitance and ESR of each electrolytic capacitor were measured over time. The capacitance and ESR values were measured using an impedance analyzer 4194A manufactured by Agilent Technologies.

  The electrostatic capacity at 120 Hz obtained with the electrolytic capacitors of Examples 1 and 2 and Comparative Example 1 are shown in FIGS. 2 to 4 together with time-dependent changes in electrostatic capacity at 10 kHz and ESR at 100 kHz. 2 to 4 show both the measurement results of two electrolytic capacitors corresponding to the respective examples and comparative examples. In FIG. 2, the results obtained in Example 1 are indicated by L11a and L11b, the results obtained in Example 2 are indicated by L12a and L12b, and the results obtained in Comparative Example 1 are indicated by L13a and L13b, respectively. In FIG. 3, the results obtained in Example 1 are indicated by L21a and L21b, the results obtained in Example 2 are indicated by L22a and L22b, and the results obtained in Comparative Example 1 are indicated by L23a and L23b, respectively. Further, in FIG. 4, the results obtained in Example 1 are indicated by L31a and L31b, the results obtained in Example 2 are indicated by L32a and L32b, and the results obtained in Comparative Example 1 are indicated by L33a and L33b, respectively.

  2 to 4, the electrolytic capacitors of Example 1 and Example 2 maintain a higher capacitance value after being maintained at 125 ° C. for 1000 hours than the electrolytic capacitor of Comparative Example 1, and It was confirmed that the ESR value after 1000 hours was kept low. From this, it was confirmed that the electrolytic capacitors of Examples 1 and 2 were able to maintain good capacitor characteristics even under high temperature conditions and had excellent heat resistance.

It is a figure which shows typically the cross-sectional structure of the electrolytic capacitor obtained by the manufacturing method which concerns on suitable embodiment. It is a figure which shows the time-dependent change of the electrostatic capacitance in 120 Hz obtained with the electrolytic capacitor of Examples 1-2 and the comparative example 1. FIG. It is a figure which shows the time-dependent change of the electrostatic capacitance in 10kHz obtained with the electrolytic capacitor of Examples 1-2 and the comparative example 1. FIG. It is a figure which shows the time-dependent change of ESR in 100 kHz obtained with the electrolytic capacitor of Examples 1-2 and the comparative example 1. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Electrolytic capacitor, 12 ... Valve metal base | substrate, 12a ... Anode part, 12b ... Cathode part, 14 ... Dielectric layer, 15 ... Electrolyte layer, 16 ... Cathode, 17 ... Carbon layer, 18 ... Silver layer.

Claims (2)

A valve metal substrate;
A dielectric layer formed on the valve metal substrate;
A solid electrolyte layer formed on the dielectric layer and containing 150-1000 ppm iron;
A conductor layer formed on the solid electrolyte layer;
An electrolytic capacitor comprising: Providing a valve metal substrate comprising a dielectric layer on at least a portion of the surface;
Attaching a polymerization solution containing an iron salt and a monomer to at least the surface of the dielectric layer in the valve metal substrate;
Polymerizing the monomer in the polymerization solution to form a solid electrolyte layer on the dielectric layer, and
In the solid electrolyte layer, 150 to 1000 ppm of iron derived from the iron salt is left.
The manufacturing method of the electrolytic capacitor characterized by the above-mentioned.

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