JP2003188052A - Solid electrolytic capacitor element and manufacturing method thereof, and solid electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technique for manufacturing a conductive polymer layer in a single layer structure, further having a film thickness of 10 to 50 μm even at an edge where surfaces cross and also a portion of the surface other than the edge in a solid electrolytic capacitor using the conduction polymer layer formed by chemical oxidation polymerization reaction for solid electrolyte. <P>SOLUTION: In a process for forming a polythiophen layer 7A, a distribution state of the amount of adhesion of oxidizer on the outer surface of an anode body is controlled, the oxidizer being adhered to the anode body, thus controlling the thickness of the polythiophen layer 7A. The amount of adhesion of the oxidizer is controlled by controlling a drying speed when the anode body is dipped into an oxidizer solution and is dried after being pulled up. The drying speed of the oxidizer solution is controlled by changing at least one of temperature, humidity, wind velocity, and atmospheric pressure in drying. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor using a conductive polymer as a solid electrolyte, an element thereof and a method for manufacturing the same, and in particular, forming a layer of a conductive polymer by a chemical oxidative polymerization reaction. Regarding technology.

[0002]

2. Description of the Related Art The structure of a solid electrolytic capacitor of this type and its manufacturing method will be described by taking a tantalum solid electrolytic capacitor as an example. Referring to FIG. 3 showing a cross section of an example of a capacitor, a tantalum solid electrolytic capacitor shown in this figure is composed of a capacitor element 1 that performs a storage action, an anode terminal 2 and a cathode terminal 3, and an outer resin 4. There is. The two terminals 2 and 3 are terminals attached to the capacitor element 1 for electrical connection to the outside, and the exterior resin 4 includes the capacitor element 1, the anode terminal 2 and the cathode terminal 3 at the positive and negative ends. It covers all but one part of the child.

The capacitor element 1 comprises a sintered body 5, a tantalum oxide film 6, a conductive polymer layer 7, a graphite layer 8 and a silver paste layer 9 which are sequentially provided on the surface of the sintered body 5.
And the anode lead 1 led out from one end surface of the sintered body 5.
It consists of 0.

The sintered body 5 is a porous body obtained by press-molding fine powder of metal tantalum into a cylinder or a prism, and sintering the powder. The sintered body 5 corresponds to the anode of the capacitor. The tantalum oxide film 6 is formed by anodizing the sintered body 5 and is made of a film of an oxidation product of metal tantalum (tantalum oxide: Ta ₂ O ₅ ) which is a base material of the sintered body and is sintered. Not only the outer surface of the body 5 but also the surface of the inner micropores, which is not shown, is covered without leaving. This tantalum oxide film 6 is the dielectric of the capacitor. The anode lead 10 connects the sintered body 5 which is the anode of the capacitor and the anode terminal 2 which is a terminal for connecting to the outside, and is made of metal tantalum powder in the form of a cylinder or cylinder when the sintered body 5 is made. At the same time when forming a prism, a tantalum wire is planted on one bottom surface of the column, so that the sintered body 5 is planted from the beginning of manufacturing. The anode terminal 2 is attached to this anode lead 10.
For example, they are fixed by a method such as resistance welding or laser welding. In the following, the combination of the sintered body 5, the tantalum oxide film 6, and the anode lead 10 may be referred to as an anode body.

The conductive polymer layer 7 provided so as to cover the tantalum oxide film 6 is a solid electrolyte. On the conductive polymer layer 7, a conductive material layer such as a graphite layer 8 and a silver paste layer 9 is further formed. The layer 8 and the silver paste layer 9 form a conductor layer that serves as the cathode of the capacitor. Then, the cathode terminal 3, which is a terminal for external connection, is fixed to the outermost layer of the cathode conductor layer with a conductive adhesive 11 or the like.

Regarding the method of forming the conductive polymer layer 7 in the context of the present invention, the conductive polymer layer 7 is formed by electrolytic oxidative polymerization or chemical oxidative polymerization of a monomer such as pyrrole. Although both forming methods have their own characteristics, the present invention relates to a method of forming a conductive polymer layer by a chemical oxidative polymerization reaction.

When the conductive polymer layer 7 is formed by a chemical oxidative polymerization reaction, it is generally formed as follows. That is, first, for example, a solution of the above-mentioned monomer and an oxidant solution are prepared. The oxidant solution can be obtained, for example, by using an oxidant such as ferric dodecylbenzene sulfonate as a solute and dissolving this in a solvent such as ethyl alcohol. Then, first, the anode body having the tantalum oxide film 6 formed thereon is dipped in the oxidant solution to allow the oxidant solution to penetrate into the fine pores inside the anode body. Then, the anode body is pulled up and dried by sending warm air in a constant temperature bath, and the oxidizing agent is attached to the outer surface and the inner surface (the surface of the fine pores in the anode body) of the anode body. next,
The anode body having the oxidant attached is dipped in the monomer solution to allow the monomer solution to permeate the inside of the anode body. And
The anode body is pulled up, and hot air is sent in a constant temperature bath to apply heat to cause a chemical oxidative polymerization reaction. Through this series of operations, the conductive polymer layer 7 is formed on the inner and outer surfaces of the anode body.

[0008] Usually, the conductive polymer having a sufficient thickness can be obtained by performing a series of operations of dipping in the above-mentioned oxidizing agent solution → pulling up → drying → dipping in a monomer solution → chemical oxidative polymerization reaction. Since a layer cannot be obtained, the above series of operations is repeated several times until the required thickness is obtained. The order of immersion in the oxidant solution and the monomer solution may be reversed from that described above, and the monomer solution may be first dipped and dried, and then the oxidant solution may be dipped to carry out the chemical oxidative polymerization reaction. .

By the way, as described above, the conductive polymer layer 7 has the graphite layer 8 and the silver paste layer 9 thereon.
It also acts as the cathode of the capacitor. Therefore, from the viewpoint of the series resistance of the cathode, the thinner one is preferable.
On the other hand, however, the conductive polymer layer also functions to protect the element from the mechanical stress applied to the capacitor element by the exterior resin 4. From this point of view, it must have a certain thickness or more. That is, the capacitor element 1
Is heating or cooling when the exterior resin 4 is formed, rapid heat or rapid cooling when the completed capacitor is soldered to a mounting board, or expansion due to temperature change of the environment in actual use after mounting, Repeat contraction. Then, the tantalum oxide film 6 is coated with the exterior resin 4 each time it expands or contracts.
Adds mechanical stress. The conductive polymer layer 7 has a function of relieving such stress and protecting the tantalum oxide film 6. Therefore, it is necessary that the thickness is a certain amount or more.

The above-mentioned action of the conductive polymer layer 7 for protecting the dielectric oxide film and the fact that the conductive polymer layer 7 must have a thickness of a certain degree or more for that purpose are described in, for example, Japanese Unexamined Patent Publication No. 2001-143968. It is already well known as described in Japanese Patent Publication. In the solid electrolytic capacitor disclosed in the above publication, when the conductive polymer layer 7 has a single-layer structure by a chemical oxidative polymerization reaction, the corner portion of the anode body (in the anode body, the lead-out surface and the side surface of the anode lead 10) The conductive polymer layer of the part surrounding the side where the and intersect, and the part surrounding the side where the other bottom and the side intersect) is formed only thinner than the other flat parts, which is the cause. In consideration of the fact that the dielectric oxide film is easily stressed at the corners, the thickness of the conductive polymer layer at the corners is made thicker than before. Therefore, the conductive polymer layer has a two-layer structure including a first layer formed by a chemical oxidative polymerization reaction and a second layer formed by a similar chemical oxidative polymerization reaction, and the reaction rate at the time of forming the second layer is The reaction rate at the time of forming the pre-polymerized film layer may be set to be higher than the reaction rate at the time of forming the first layer, or by forming the pre-polymerized film layer in advance before forming the first layer to form a three-layer structure. The speed is set to be higher than the reaction speed at the time of forming the first layer.

[0011]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
According to the conductive polymer layer forming technique described in Japanese Patent No. 143968, the thickness of the corner portion of the anode body is at most 1 to 2 μm in the conductive polymer layer having a single layer structure by the chemical oxidation polymerization reaction up to that point. By the way, it can be thickened to 5 to 100 μm.

However, in the method of forming a conductive polymer layer described in the above publication, the structure and manufacturing process are complicated even if the conductive polymer layer has a multi-layer structure.
In addition, the reaction rate during the formation of the second layer must be faster than the reaction rate during the formation of the first layer, which makes it difficult to control the production conditions and, in some cases, newly installs or enhances the production equipment. And so on.

In addition, although the conductive polymer layer at the corner can be made thicker than before, no consideration is given to the thickness of other portions. As described above, the thickness of the conductive polymer layer 7 is preferably thin from the viewpoint of series resistance at the cathode of the capacitor, while it is preferably thick from the viewpoint of the effect of protecting the dielectric oxide film. However, if the conductive polymer layer is too thick, the external dimensions of the capacitor element become large, so that the thickness of the exterior resin 4 becomes thin, cracks are likely to occur, and reliability deteriorates. In the worst case, the element is exposed from the exterior resin 4, making it useless as a capacitor. In the solid electrolytic capacitor according to the above publication, for example, as shown in FIG. 13 and the like, the conductive polymer layer tends to be formed thicker in the other surface portion than in the corner portion. Therefore, if the conductive polymer layer at the corner portion has an appropriate thickness, the surface portion other than the corner portion becomes too thick, resulting in cracks in the exterior resin or defective element exposure from the exterior resin as described above. May occur.

The inventors of the present invention have proposed a capacitor using a conductive polymer by a chemical oxidative polymerization reaction as a solid electrolyte.
FIG. 4 shows the result of investigation on the relationship between the thickness of the conductive polymer layer, the defective rate of leakage current of the capacitor, and the defective rate of element exposure from the exterior resin 4. In FIG. 4, when the mechanical stress applied to the capacitor element from the exterior resin 4 is the same, the actual leakage stress applied to the tantalum oxide film 6 depends on the thickness of the conductive polymer layer 7 in FIG. It may be considered that it depends on the above, that is, it represents the stress relieving ability of the conductive polymer layer 7. However, the leakage current defective rate is higher as the conductive polymer layer 7 is thinner. . In other words, the stress relaxation ability of the conductive polymer layer 7 is small, and a large stress is applied to the tantalum oxide film 6.
Particularly, when the film thickness of the conductive polymer layer 7 is 10 μm or less, the leakage current defective rate increases rapidly. On the other hand, the defective element exposure rate is higher as the conductive polymer layer 7 is thicker.
When the film thickness of the conductive polymer layer 7 is 50 μm or more, it rapidly increases.
Therefore, it is desirable that the thickness of the conductive polymer layer 7 is in the range of 10 to 50 μm. However, in the solid electrolytic capacitor described in the above publication, the thickness of the conductive polymer layer on the surface portion other than the corner portion. Since the height is not specified, the above-described defective element exposure may occur.

As will be clarified later, the thickness distribution state of the conductive polymer layer 7 on the outer surface of the anode body greatly changes depending on the drying method after the anode body is pulled out from the oxidant solution. In the above publication, no consideration is given to the thickness of the conductive polymer layer on the surface portion other than the corner portion, and the thickness of the conductive polymer layer on the surface portion and the conductive polymer layer on the corner portion are There is no idea to try to control the thickness at the same time. Therefore, even if the conductive polymer layer at the corner is made thicker than before, at the cost of making the conductive polymer layer a multilayer structure of two or three layers and complicating the structure and manufacturing conditions, It is highly possible that the conductive polymer layer becomes too thick on the surface other than the corners, resulting in a decrease in reliability and a decrease in the yield rate due to the above-mentioned exterior resin cracks and element exposure from the exterior resin. turn into.

Therefore, according to the present invention, in a solid electrolytic capacitor using a conductive polymer layer formed by a chemical oxidative polymerization reaction as a solid electrolyte, the conductive polymer layer has a single-layer structure, and even at the intersections of faces. 10-50 even in other parts
It is an object of the present invention to provide a technique for forming a film having a thickness of μm.

[0017]

The solid electrolytic capacitor element of the present invention is an anode body formed by forming powder of valve action metal into a columnar body and sintering it to form an oxide film of valve action metal of a base material. And a conductive polymer layer formed on the surface of the oxide film, wherein the conductive polymer layer has a single-layer structure formed by chemical oxidative polymerization of monomers. The thickness of the outer surface of the columnar body is 10 μm or more and 50 μm or less.

In the solid electrolytic capacitor element described above, a process of forming powder of valve action metal into a columnar body and sintering it to form an oxide film of valve action metal of a base material to obtain an anode body, and an oxidizing agent. In the method for producing a solid electrolytic capacitor element, which comprises a step of forming a conductive polymer layer on the surface of the oxide film by a chemical oxidative polymerization reaction with a monomer, in the step of forming the conductive polymer layer, By controlling the distribution state of the amount of the oxidant attached to the anode body on the outer surface of the anode body, the thickness of the conductive polymer layer formed on the outer surface of the anode body is 10 μm or more. , 50 μm or less, and the solid electrolytic capacitor element is manufactured by the method for manufacturing a solid electrolytic capacitor element.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 showing a cross section of a tantalum solid electrolytic capacitor element according to an embodiment of the present invention;
Compared with FIG. 3 showing a cross section of an example of a tantalum solid electrolytic capacitor according to a conventional technique, the capacitor elements shown in both figures show a conductive polymer layer 7A which is a solid electrolyte,
7 is a single layer structure formed by a chemical oxidative polymerization reaction, and is the same in that respect. However, the capacitor element 1A according to the present embodiment has the thickness t _E of the conductive polymer layer 7A at the edge portion.
And the thickness t _P of the conductive polymer layer on the surface other than the edge portion
Is equal to and is in the range of 10 μm ≦ t _E = t _P ≦ 50 μm.

Now, the capacitor element 1 according to the present embodiment.
A is a rectangular parallelepiped having a thickness of 1.5 mm, a length of 4 mm and a width of 3 mm. The conductive polymer layer 7A had a thickness in the range of 10 to 50 μm in all of the six face portions of the sintered body and the 12 edge portions formed by the intersection of these six faces. . In the following, when referring to all sides of a columnar body (12 sides in the case of a prism, two circles in the case of a cylinder), they are referred to as "edge portions". Although the concept is similar to the “corner part” in the above-mentioned Japanese Patent Laid-Open No. 2001-143968, whether or not the “corner part” in the above-mentioned publication includes four sides formed by intersections of side surfaces of a prism is not necessarily required. Since it is not clear, different terms are intentionally used to clarify that the above four sides are also included.

The present inventors produced the tantalum solid electrolytic capacitor element shown in FIG. 1 as follows. First, an anode body is formed by a conventionally known method. That is,
The metal tantalum powder is press-molded and sintered to form a rectangular parallelepiped (thickness: 1.5 mm, length: 4 mm, width: 3 mm) sintered body 5. In that case, the anode lead 10 is formed on one bottom surface of the rectangular parallelepiped at the same time when the tantalum powder is pressed.
Plant the tantalum wire that will become. After that, anodization is performed to form an oxide film 6 of metal tantalum as a base material on the outer surface of the sintered body and the surfaces of the fine pores inside, to obtain an anode body.

Then, on the tantalum oxide film 6,
Single layer polythiophene layer 7 by chemical oxidative polymerization reaction
Form A. This layer is a conductive polymer layer. To form the polythiophene layer 7A, thiophene is used as the monomer solution, and a solution of ferric dodecylbenzene sulfonate dissolved in ethyl alcohol is used as the oxidant solution. Then, a series of operations of first immersing the anode body in the oxidant solution, pulling it up, blowing warm air to dry it, then immersing it in the monomer solution, pulling it up, sending warm air to heat it for oxidative polymerization Is repeated until the polythiophene layer 7A has a target thickness.

Prior to the formation of the above-mentioned polythiophene layer 7A, the present inventors investigated the relationship between the drying rate of the oxidizing agent and the thickness of the polythiophene layer in the edge portion of the anode body and other portions. Then, it was found that the relationship between the thickness of the polythiophene layer at the edge portion of the anode body and the thickness formed at the portion other than the edge portion can be controlled by controlling the drying speed after pulling up the anode body from the oxidant solution. It was Figure 2 shows the survey results. Referring to FIG. 2, the horizontal axis represents the drying rate V of the oxidant. Drying speed is V
= Ratio of the weight per minute that decreases with the progress of drying to the weight of the oxidant solution attached to the anode body (wt% /
Min)), which is nothing but the evaporation rate of the solvent in the oxidant solution. The vertical axis represents the thickness (μm) of the polythiophene layer 7A. A solid line of a black circle indicates the thickness at the edge portion, and a curved mountain-shaped curve having a peak at a drying rate V = 0.3 wt% / min is drawn. The broken line with white circles indicates the thickness of the surface portion other than the edge portion, and a curve showing a saturation tendency that monotonically increases with an increase in the drying speed V is drawn. And the drying speed V is about 0.4 wt%
When it is slower than / min (on the left side in the graph), the polythiophene layer at the edge portion is thicker than the other portions, while when the drying speed V is faster than 0.4 wt% / min (the right side). The edge part is thinner than the other surface parts.

The reason why the thickness of the polythiophene layer 7A has the curved shape as described above is considered as follows. That is, so far, the present inventors have found that when the oxidizing agent is not dried, the conductive polymer layer can be formed even in this case, but it cannot be used as a capacitor element because it does not fix on the surface of the anode body. Experienced that the main point in the formation of the conductive polymer layer as a solid electrolyte is that the conductive polymer layer is fixed on the surface of the anode body by sufficiently drying and fixing the oxidizing agent on the surface of the anode body. ing.
The thickness of the conductive polymer layer formed on the outer surface of the anode body is
It depends on the amount of the oxidizer fixed on the anode body. Next, in general, an organic solvent such as ethyl alcohol is used as the solvent of the oxidant solution, and immediately after the anode body is immersed in the oxidant solution and pulled up, other than the edge part, A large amount of the solution adheres to the surface part of the surface, and the drying and the deposition of the oxidant start from the edge part where the amount of the liquid adhered is small.

Therefore, first, considering the case where the drying speed V is slow, in this case, since the solvent slowly evaporates, the undried liquid on the surface of the surface where the drying is delayed will reach the edge where the drying has proceeded. After being attracted and eventually after drying, the amount of the oxidant attached to the edge portion is larger than the amount of the oxidant attached to the surface portion. Then, the difference in the adhesion amount of the oxidant appears as the difference in the thickness of the conductive polymer layer. This is a region where the drying rate V is 0.4 wt% / min or less in the graph shown in FIG.

On the other hand, when the drying speed V is high, the solvent evaporates quickly, and there is no time to draw the liquid of the surface portion to the edge portion, so that the oxidizer adheres to the anode body after drying. The state directly reflects the state of adhesion of the oxidant solution to each part of the anode body immediately after being pulled up from the oxidant solution. That is, the amount of the oxidant attached to the edge portion becomes smaller than the amount of the oxidant attached to the surface portion, and the conductive polymer layer also becomes thinner at the edge portion. This is a region where the drying rate V is 0.4 wt% / min or more in the graph shown in FIG.

When the drying speed becomes slower than a certain limit (V = 0.3 wt% / min or less), the surface of the anode body remains wet and does not dry, so that the conductive polymer formed has an edge portion. However, it becomes difficult to fix even on the flat part and it becomes thin,
In the later case (V = 0.1 wt% / min or less), almost no formation occurs. On the other hand, when the drying speed is sufficiently high (V = 0.7 wt% / min or more), both the edge portion and the flat surface portion show a saturation tendency determined by the amount of liquid adhering to the anode body.

From the above results, the drying rate V of the oxidant solution is
Is about 0.4 wt% / min, the thickness of the polythiophene layer at the edge portion and the thickness of other portions can be made the same. The drying rate V of the oxidant is
It can be controlled by temperature, wind speed and atmospheric pressure. In this embodiment, temperature: 25 ° C., humidity: 60% RH, wind speed: 0.5 m
The oxidizing agent was dried under the conditions of / s and atmospheric pressure: 1 atmospheric pressure.

According to the investigation results shown in FIG. 2, even if the drying rate V of the oxidant solution is not exactly 0.4 wt% / min, V
= 0.1 to 0.5 wt% / min, the total thickness of the polythiophene layer on the outer surface of the anode body is 10 to 10.
It can be set within 50 μm. At this time, the thickness t _E of the polythiophene layer at the edge portion and the thickness t _{P of} the surface portion are made thicker at the flat portion so that the flat portion is thicker by changing the drying speed V. You can do it either way, but the difference between both thicknesses Δ
t is the maximum when the drying speed V = 0.5 wt% / min.
_P = 50 μm, t _E = 30 μm, and Δt = 20 μm.

The drying speed V is controlled by temperature, humidity, wind speed and atmospheric pressure, but it is not necessary to limit it to the above-mentioned numerical values. Changing the four factors of temperature, humidity, wind speed, and atmospheric pressure means changing the vapor pressure of the solvent on the surface of the anode body to control the drying rate V of the oxidant solution. There is no need to fix the numerical values of the above four factors as long as the values are within the range of 0.1 to 0.5 wt% / min. Further, even when changing the above four factors, any factor may be changed. Furthermore, the number of factors is not limited to one, and some factors may be combined and changed.

This example is an example in which an ethyl alcohol solution of thiophene and ferric dodecylbenzene sulfonate is used as the monomer and the oxidant solution, but other monomers such as pyrrole, for example, It was confirmed that the same action and effect as in the present example can be obtained even when another oxidizing agent such as cupric dodecylbenzene, ferric butylnaphthalene sulfonesan or cupric butylnaphthalenesulfonesan is used.

Although the present embodiment is an example in which the present invention is applied to a tantalum solid electrolytic capacitor, the present invention is applied to a capacitor element using another valve action metal other than tantalum, such as aluminum. It will be apparent that the same effect as the embodiment can be obtained.

[0033]

As described above, according to the present invention,
In a solid electrolytic capacitor using a conductive polymer layer by a chemical oxidative polymerization reaction in the solid electrolyte, the conductive polymer layer has a single-layer structure, moreover, even at the intersection of the surface and the surface and the other part, It can be formed to have a film thickness of 10 to 50 μm.

[Brief description of drawings]

FIG. 1 is a sectional view of a tantalum solid electrolytic capacitor element according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a drying rate of an oxidant and a thickness of a conductive polymer layer in an edge portion of an anode body and other portions.

FIG. 3 is a cross-sectional view of a conventional solid electrolytic capacitor.

FIG. 4 is a diagram showing the relationship among the thickness of a conductive polymer layer, the leakage current defect rate, and the element exposure defect rate.

[Explanation of symbols]

1A capacitor element 2 Anode terminal 3 cathode terminal 4 Exterior resin 5 Sintered body 6 Tantalum oxide film 7A conductive polymer layer 8 Graphite layer 9 Silver paste layer 10 Anode lead 11 Conductive adhesive

Claims (8)

[Claims] 1. An anode body comprising a valve metal powder formed into a columnar body and sintered to form an oxide film of a valve metal of a base material, and a conductive material formed on the surface of the oxide film. In a solid electrolytic capacitor element including a polymer layer, the conductive polymer layer has a single layer structure formed by chemical oxidative polymerization of monomers, and the columnar body has a thickness of 10 μm or more on an outer surface. And 50 μm or less, a solid electrolytic capacitor element. 2. The difference between the thickness of the conductive polymer layer in the portion where each surface of the columnar body intersects and the thickness of the conductive polymer layer in the other portion is ± 20 μm or less. The solid electrolytic capacitor element according to claim 1. 3. A method for manufacturing the solid electrolytic capacitor element according to claim 1 or 2, wherein a powder of valve action metal is formed into a columnar body and sintered to obtain a valve action metal of a base material. Manufacture of a solid electrolytic capacitor element including a step of forming an oxide film to obtain an anode body and a step of forming a layer of a conductive polymer on the surface of the oxide film by a chemical oxidative polymerization reaction of an oxidizing agent and a monomer In the method, in the process of forming the layer of the conductive polymer, the oxidizing agent to be attached to the anode body, by controlling the distribution state of the deposition amount on the outer surface of the anode body, to the outer surface of the anode body. A method for manufacturing a solid electrolytic capacitor element, characterized in that the thickness of the conductive polymer layer formed is controlled within the range of 10 μm or more and 50 μm or less. 4. The step of forming the conductive polymer layer, the step of immersing the anode body in a solution containing an oxidant, the process of pulling it up and drying to attach the oxidant to the anode body, The step of immersing the anode body having the oxidant attached thereto in a solution containing the monomer to attach the monomer and the step of causing the oxidant and the monomer to undergo a chemical oxidative polymerization reaction in this order are repeated at least once or more. 4. The distribution state of the amount of attached oxidant on the outer surface of the anode body is controlled by controlling the drying speed in each process of attaching the oxidant.
A method for manufacturing the solid electrolytic capacitor element as described in 1. 5. The rate of drying V in the process of depositing the oxidant is expressed as a percentage of the weight of the solution containing the oxidant, which decreases per minute with respect to the weight deposited on the anode body by immersion. , 0.1 wt% / min ≦ V ≦
The solid electrolytic capacitor element manufacturing method according to claim 4, wherein the solid electrolytic capacitor element is 0.5 wt% / min. 6. A process of forming a powder of valve metal into a columnar body and sintering it to form an oxide film of valve metal of a base material to obtain an anode body, and the anode body containing the oxidizing agent. The rate of drying of the solution containing the oxidant attached to the anode body by immersing in the solution, pulling up, V = weight attached to anode body by immersion / weight reduced per minute by drying is 0.1 wt% / min ≤V≤0.
The thickness on the outer surface of the anode body is repeated at least once by drying to 5 wt% / min, immersing in a solution containing a monomer, pulling it up, and chemically polymerizing the oxidant and the monomer. Is 10 μm or more,
And a step of forming a layer of a conductive polymer so as to have a thickness of 50 μm or less. 7. The method according to claim 4, wherein the rate of drying the solution containing the oxidant attached to the anode body is controlled by the temperature, humidity, atmospheric pressure and wind speed of the drying atmosphere. Item 7. A method for manufacturing a solid electrolytic capacitor element as described in the item. 8. A solid electrolytic capacitor in which the solid electrolytic capacitor element according to claim 1 is provided with an anode terminal and a cathode terminal for connection to the outside, and an exterior is provided, wherein Ta is used for the valve action metal. A solid electrolytic capacitor characterized by being used.