JP2024070568A - Solid electrolytic capacitor and method for manufacturing solid electrolytic capacitor - Google Patents

Abstract

To provide a solid electrolytic capacitor and a method for manufacturing a solid electrolytic capacitor that can simplify manufacture.SOLUTION: A solid electrolytic capacitor 1 has a valve metal base 9 having an anode terminal area 9a and a cathode forming area 9b and constituting an anode portion 3, and a cathode portion 5 provided on the cathode forming area 9b of the valve metal base 9, the cathode portion 5 has a solid electrolyte layer 13 disposed on the surface of a dielectric layer 11 provided at least on the cathode forming area 9b of the valve metal base 9 and a metal plating layer 15 disposed on the surface of the solid electrolyte layer 13, and the solid electrolyte layer 13 contains a non-water soluble conductive polymer containing a doping material of average molecular weight of 1000 to 100000, and the metal plating layer 15 is an electrolytic plating layer.SELECTED DRAWING: Figure 1

Description

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

A known example of a conventional solid electrolytic capacitor is the one described in Patent Document 1. The solid electrolytic capacitor described in Patent Document 1 includes a valve metal base constituting an anode part having an anode terminal region and a cathode forming region, and a cathode part formed by laminating a solid electrolyte layer and a conductor layer on an oxide film provided on the surface of the cathode forming region of the valve metal base. The conductor layer is composed of a carbon paste layer and a silver paste layer.

Patent No. 4677775

As in the solid electrolytic capacitor described above, the cathode is formed by laminating a solid electrolyte layer and a conductive layer. The conductive layer is composed of a carbon paste layer and a silver paste layer. Therefore, the manufacturing of a solid electrolytic capacitor requires the steps of forming a solid electrolyte layer, a carbon paste layer, and a silver paste layer.

One aspect of the present invention aims to provide a solid electrolytic capacitor that can be manufactured more simply and a method for manufacturing a solid electrolytic capacitor.

(1) A solid electrolytic capacitor according to one aspect of the present invention includes a valve metal substrate having an anode terminal region and a cathode formation region, constituting an anode portion, and a cathode portion provided in the cathode formation region of the valve metal substrate. The cathode portion includes a solid electrolyte layer disposed on the surface of a dielectric layer provided on at least the cathode formation region of the valve metal substrate, and a metal plating layer disposed on the surface of the solid electrolyte layer. The solid electrolyte layer includes a water-insoluble conductive polymer containing a doping material having a number-average molecular weight of 1,000 or more and 100,000 or less, and the metal plating layer is an electrolytic plating layer.

In the solid electrolytic capacitor according to one aspect of the present invention, the solid electrolyte layer includes a water-insoluble conductive polymer containing a doping material having a number-average molecular weight of 1000 to 100,000. In this way, by using a doping material having a number-average molecular weight of 1000 to 100,000, when the metal plating layer is formed by electrolytic plating, the doping material is retained in the solid electrolyte layer, so that no current is generated due to dedoping, and electrons can be supplied by passing electricity on the surface of the solid electrolyte layer, and the metal plating layer can be formed on the surface of the solid electrolyte layer by electrolytic plating. Therefore, in the solid electrolytic capacitor, the cathode part can be composed of two layers, the solid electrolyte layer and the metal plating layer. That is, the cathode part does not have a conductive layer between the solid electrolyte layer and the metal plating layer. Therefore, the solid electrolytic capacitor can be simplified in configuration compared to a cathode part including a solid electrolyte layer, a carbon paste layer, and a silver paste layer. As a result, the solid electrolytic capacitor can be simplified in manufacturing.

(2) In the solid electrolytic capacitor of (1) above, the water-insoluble conductive polymer may be polypyrrole or poly(3,4-ethylenedioxythiophene).

(3) In the solid electrolytic capacitor of (2) above, the doping material may be a sulfonic acid derivative. In this configuration, the doping material can be dissolved in a polymer polymerization solution for forming a water-insoluble conductive polymer by polymerization, and the solid electrolyte layer can be made conductive.

(4) In the solid electrolytic capacitor of (3) above, the doping material may be polystyrene sulfonic acid-based or phenol sulfonic acid-based.

(5) In the solid electrolytic capacitors described above in (1) to (4), the concentration of the doping material in the water-insoluble conductive polymer in the solid electrolyte layer may be 1% or more and 200% or less. With this configuration, the solid electrolyte layer can have stable conductivity.

(6) In any one of the solid electrolytic capacitors (1) to (5) above, the metal plating layer may be an electrolytic plating layer made of a copper layer. A copper plating layer has excellent electrical conductivity. Therefore, the equivalent series resistance of the solid electrolytic capacitor can be reduced.

(7) A method for manufacturing a solid electrolytic capacitor according to one aspect of the present invention includes a preparation step of preparing a valve metal substrate, a solid electrolyte layer formation step of forming a solid electrolyte layer on the valve metal substrate, and a plating layer formation step of forming a metal plating layer on the solid electrolyte layer by electrolytic plating. In the solid electrolyte layer formation step, a polymerization process is performed including a step of immersing the valve metal substrate in a polymerization solution containing a water-insoluble conductive polymer containing a doping material having a number average molecular weight of 1,000 or more and 100,000 or less, to form a solid electrolyte layer.

In the method for manufacturing a solid electrolytic capacitor according to one aspect of the present invention, in the solid electrolyte layer forming step, a polymerization process including a step of immersing a valve metal substrate in a polymerization solution containing a water-insoluble conductive polymer containing a doping material having a number-average molecular weight of 1000 to 100,000 is performed to form a solid electrolyte layer. In this way, by using a doping material having a number-average molecular weight of 1000 to 100,000, when a metal plating layer is formed by electrolytic plating, the doping material is retained in the solid electrolyte layer, so that no current is generated due to dedoping, and electrons can be supplied by passing electricity on the surface of the solid electrolyte layer, and the metal plating layer can be formed on the surface of the solid electrolyte layer by electrolytic plating. Therefore, in the solid electrolytic capacitor, the cathode part can be composed of two layers, the solid electrolyte layer and the metal plating layer. That is, the cathode part does not have a conductive layer between the solid electrolyte layer and the metal plating layer. Therefore, the solid electrolytic capacitor can be simplified in configuration compared to a cathode part including a solid electrolyte layer, a carbon paste layer, and a silver paste layer. As a result, the method for manufacturing a solid electrolytic capacitor can be simplified in manufacturing.

According to one aspect of the present invention, manufacturing can be simplified.

FIG. 1 is a cross-sectional view of a solid electrolytic capacitor according to an embodiment. FIG. 2 is an enlarged cross-sectional view showing in detail a portion of the structure of the solid electrolytic capacitor shown in FIG. FIG. 3 is a cross-sectional view of a capacitor structure.

A preferred embodiment of the present invention will be described in detail below with reference to the attached drawings. In the description of the drawings, the same or equivalent elements are given the same reference numerals, and duplicate descriptions will be omitted.

Figure 1 is a cross-sectional view of a solid electrolytic capacitor according to one embodiment. Figure 2 is an enlarged cross-sectional view showing in detail a portion of the structure of the solid electrolytic capacitor shown in Figure 1. As shown in Figures 1 and 2, the solid electrolytic capacitor 1 includes an anode portion 3, a cathode portion 5, and an insulating portion 7.

The anode portion 3 is composed of a valve metal substrate 9. As shown in FIG. 2, the surface of the valve metal substrate 9 is roughened or enlarged (chemical conversion treatment) to form a fine uneven shape. The material constituting the valve metal substrate 9 is not particularly limited as long as it is one that is generally used in electrolytic capacitors, and examples of the material include so-called valve metals such as aluminum, tantalum, niobium, titanium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony. Of these, aluminum or tantalum is relatively preferably used. The valve metal substrate 9 composed of these valve metals is also called a valve metal layer. The thickness of the valve metal substrate 9 is, for example, about 1 μm to 500 μm.

The valve metal substrate 9 has an anode terminal region 9a and a cathode formation region 9b. The anode terminal region 9a is a region that functions as a terminal for the anode portion 3. The cathode formation region 9b is a region where the cathode portion 5 is formed.

As shown in FIG. 2, a dielectric layer 11 is formed on the surface of the cathode formation region 9b of the valve metal substrate 9. The dielectric layer 11 is usually a metal oxide film having electrical insulation properties (for example, an aluminum oxide film when the valve metal substrate 9 is made of aluminum). The dielectric layer 11 is formed by oxidizing the surface layer of the valve metal substrate 9 by a predetermined method. The thickness of the dielectric layer 11 is, for example, about 1 nm to 1 μm.

The cathode section 5 is configured to include a solid electrolyte layer 13 and a metal plating layer 15. The cathode section 5 is provided on the surface (upper surface, lower surface, and side surface) of the cathode formation region 9b in the valve metal substrate 9. The cathode section 5 is configured by laminating the solid electrolyte layer 13 and the metal plating layer 15 on the dielectric layer 11. Specifically, in the cathode section 5, the solid electrolyte layer 13 and the metal plating layer 15 are laminated in this order from the dielectric layer 11 side.

The solid electrolyte layer 13 is formed along the dielectric layer 11 on the finely uneven surface of the valve metal substrate 9 formed by surface enlarging, so as to fill the recesses 9c. The thickness of the solid electrolyte layer 13 is preferably such that it can cover the uneven surface. The thickness of the solid electrolyte layer 13 is, for example, about 1 μm to 100 μm.

The solid electrolyte layer 13 is composed of a conductive polymer. Specifically, the solid electrolyte layer 13 is composed of a non-water-soluble conductive polymer containing a doping material. As the non-water-soluble conductive polymer compound, a commonly used one can be used, for example, polypyrrole, polyaniline, polythiophene, polyfuran, and derivatives thereof, and poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (ppy) are preferably used. These may be used alone or in a mixture of two or more.

The doping material must be soluble in the polymer polymerization solution, must be able to penetrate (diffuse) into the uneven shape of the valve metal substrate 9, and must not leave the conductive polymer film even when a reverse bias is applied during electrolytic plating to form the metal plating layer 15. As the doping material, a sulfonic acid derivative can be used, for example, an aromatic sulfonic acid compound such as polystyrene sulfonic acid, phenol sulfonic acid, paratoluene sulfonic acid, naphthalene sulfonic acid, or anthraquinone sulfonic acid, and polystyrene sulfonic acid and phenol sulfonic acid are preferably used.

The molecular weight of the doping material is a number average molecular weight of 1000 or more and 100,000 or less. The molecular weight of the doping material is preferably 1000 or more in number average molecular weight so that it does not leave the conductive polymer film even when a reverse bias is applied in the electrolytic plating method. On the other hand, the number average molecular weight is preferably 100,000 or less in terms of the need to penetrate into the uneven shape of the dielectric layer 11 formed on the valve metal substrate 9. The concentration of the doping material is 1% or more and 200% or less, preferably 5% or more and 150% or less, relative to the water-insoluble conductive polymer compound. This allows the solid electrolyte layer 13 to have stable conductivity.

The metal plating layer 15 is formed on the surface of the solid electrolyte layer 13. Specifically, the metal plating layer 15 is formed on the surface of the solid electrolyte layer 13 opposite to the surface where the solid electrolyte layer 13 is in contact with the dielectric layer 11. The metal plating layer 15 is a plating layer formed by electrolytic plating. The metal constituting the metal plating layer 15 may be copper, nickel, tin, or the like, with copper being particularly preferred. These may be used alone or in a mixture of two or more types.

As shown in FIG. 1, the insulating portion 7 is formed on the surface (upper surface, lower surface, and side surface) of the boundary portion between the anode terminal region 9a and the cathode formation region 9b in the valve metal substrate 9. In addition to the function of electrically insulating the anode portion 3 and the cathode portion 5, the insulating portion 7 also has the function of preventing the solution from creeping up during immersion processes such as the conductive polymer polymerization process and the paste application process. The width of the insulating portion 7 is, for example, 0.1 mm to 1.0 mm. The thickness of the insulating portion 7 is, for example, 1 μm to 50 μm, and preferably 10 μm to 40 μm.

The insulating portion 7 may be composed of two resist portions. For example, it may have a first resist portion formed on the surface of the valve metal base 9 so as to separate the anode terminal region 9a and the cathode forming region 9b of the valve metal base 9, and a second resist portion formed continuously across the surface of the first resist portion on the anode terminal region 9a side and the surface of the valve metal base 9. The first resist portion and the second resist portion are formed so as to extend in the width direction of the valve metal base 9 from one side to the other side of the solid electrolytic capacitor 1. In other words, the second resist portion is formed entirely in the extension direction of the first resist portion relative to the first resist portion. The first resist portion is formed of a hydrophilic resin, such as an epoxy resin. The second resist portion is formed of a hydrophobic (water-repellent) resin, such as a silicone resin or a fluororesin.

Next, a method for manufacturing the solid electrolytic capacitor 1 will be described. First, a valve metal substrate 9 with a roughened and chemically treated surface is prepared, and the valve metal substrate 9 is punched into a predetermined shape using a die (preparation step).

Next, an insulating portion 7 is formed on the surface of the boundary between the anode terminal region 9a and the cathode formation region 9b of the chemically treated valve metal substrate 9 using a printing method, a dispenser, an inkjet method, a transfer method, or the like. Next, a dielectric layer 11 is formed on the surface (cut surface) of the edge portion of the valve metal substrate 9 exposed by the above die punching process.

Then, a solid electrolyte layer 13 is formed on the surface of the cathode formation region 9b of the valve metal substrate 9 by electrolytic polymerization, chemical oxidation polymerization, or the like (solid electrolyte formation process). In this embodiment, the solid electrolyte layer 13 is formed by immersing the cathode formation region 9b of the valve metal substrate 9 in a polymerization solution in a polymerization tank and performing electrolytic polymerization.

More specifically, a polymerization solution is prepared that contains the monomers that constitute the conductive polymer compound described above, a doping material, and, if necessary, additives such as a proton-donating polymer compound.

In the case of electrolytic polymerization, a current is passed through the seed material formed on the dielectric layer 11 on the cathode formation region 9b to electrolytically oxidize the monomer and cause a polymerization reaction. In addition to conductive polymers, organic semiconductors such as manganese dioxide and TTF-TCNQ can be used as the seed material.

In the case of chemical oxidation polymerization, an oxidizing agent is further added to the polymerization solution to carry out the polymerization reaction. The solvent used in preparing these polymerization solutions is a polar solvent such as water or alcohol. As alcohol, ethanol and propanol are preferred. When an additive is added to the polymerization solution, it is preferred to use a solvent capable of dissolving the additive. These solvents may be used alone or in combination of two or more.

In addition, examples of monomers include aniline, pyrrole, thiophene, furan, and derivatives thereof, and by polymerizing these, conductive polymer compounds such as polyaniline, polypyrrole, polythiophene, polyfuran, and derivatives thereof can be obtained.

Oxidizing agents used in chemical oxidation polymerization include halides such as iodine and bromine, metal halides such as silicon pentafluoride, protonic acids such as sulfuric acid, oxygen compounds such as sulfur trioxide, sulfates such as cerium sulfate, persulfates such as ammonium persulfate and sodium persulfate, peroxides such as hydrogen peroxide, and iron salts such as ferric paratoluene.

This polymerization solution is used to perform chemical oxidation polymerization to form a solid electrolyte layer 13 on the dielectric layer 11 of the valve metal substrate 9. In the chemical oxidation polymerization process, the valve metal substrate 9 is immersed in the polymerization solution, and then the valve metal substrate 9 is pulled out of the polymerization solution to perform an immersion step. This causes the polymerization solution to adhere to the surface of the valve metal substrate 9.

Next, the valve metal substrate 9 is lifted out of the polymerization solution and left to stand. This allows the oxidative polymerization reaction of the monomers in the polymerization solution attached to the surface of the valve metal substrate 9 to proceed, producing a conductive polymer compound. In addition, in the leaving step, the valve metal substrate 9 with the polymerization solution attached thereto may be left in a high-temperature environment in order to promote the oxidative polymerization reaction of the monomers. In addition, the leaving time in the leaving step is not particularly limited, and can be appropriately determined according to the composition and solids concentration of the polymerization solution used, or other conditions. Note that since the above polymerization solution contains an oxidizing agent as well as the monomers, a small amount of polymerization reaction may also occur in the immersion step before the leaving step.

After the polymerization reaction, the surface of the valve metal substrate 9 is washed. Here, washing is performed by removing impurities on the surface of the valve metal substrate 9 using a washing liquid such as water or alcohol, spraying the washing liquid onto the valve metal substrate 9, or immersing the valve metal substrate 9 in the washing liquid. In addition, in the washing step, it is preferable to further dry the valve metal substrate 9 after washing. This removes liquids such as the washing liquid adhering to the valve metal substrate 9. Through the steps described above, a polymerization process is performed to polymerize the monomer to form the solid electrolyte layer 13, and the solid electrolyte layer 13 is formed (solid electrolyte layer forming step).

Next, a metal plating layer 15 is formed on the solid electrolyte layer 13 using an electrolytic plating method (plating layer formation process). This forms the cathode portion 5. In this way, the solid electrolytic capacitor 1 is obtained.

Figure 3 is a cross-sectional view of the capacitor structure. As shown in Figure 3, the capacitor structure 100 is configured to include multiple solid electrolytic capacitors 1. The capacitor structure 100 includes multiple solid electrolytic capacitors 1, a molded portion 110, a connecting portion 120, and an adhesive portion 130. In this embodiment, the capacitor structure 100 is configured to include three solid electrolytic capacitors 1. In the following description, for convenience of explanation, the three solid electrolytic capacitors 1 may be distinguished and referred to as solid electrolytic capacitor 1A, solid electrolytic capacitor 1B, and solid electrolytic capacitor 1C.

The molded part 110 molds a plurality of solid electrolytic capacitors 1. The molded part 110 constitutes the exterior of the capacitor structure 100. The molded part 110 is made of an insulating resin material such as epoxy resin. The molded part 110 has a first terminal electrode 140 and a second terminal electrode 150. The first terminal electrode 140 and the second terminal electrode 150 are parts that are mounted on a circuit board or the like.

The connection portion 120 is formed of a conductive material. The connection portion 120 electrically connects the anode portions 3 of the multiple solid electrolytic capacitors 1A to 1C. The connection portion 120 is, for example, welded or crimped. One end (lower end) of the connection portion 120 is connected to the first terminal electrode 140. As a result, the anode portions 3 of the solid electrolytic capacitors 1A to 1C are electrically connected to the first terminal electrode 140. Note that the anode portions 3 of the solid electrolytic capacitor 1C may be directly connected (placed) to the first terminal electrode 140, thereby electrically connecting the anode portions 3 of the solid electrolytic capacitors 1A to 1C to the first terminal electrode 140.

The adhesive portion 130 bonds the adjacent solid electrolytic capacitors 1A to 1C. The adhesive portion 130 is a conductive adhesive. The adhesive portion 130 electrically connects (joins) the cathode portions 5 of the adjacent solid electrolytic capacitors 1A to 1C. Specifically, the adhesive portion 130 joins the cathode portion 5 of the solid electrolytic capacitor 1A to the cathode portion 5 of the solid electrolytic capacitor 1B. The adhesive portion 130 also joins the cathode portion 5 of the solid electrolytic capacitor 1B to the cathode portion 5 of the solid electrolytic capacitor 1C. A portion of the cathode portion of the solid electrolytic capacitor 1C is disposed on the second terminal electrode 150. With this configuration, the cathode portions 5 of the solid electrolytic capacitors 1A to 1C are electrically connected to the second terminal electrode 150.

As described above, in the solid electrolytic capacitor 1 according to this embodiment, the solid electrolyte layer 13 includes a water-insoluble conductive polymer containing a doping material having a number-average molecular weight of 1000 to 100,000. In this way, by using a doping material having a number-average molecular weight of 1000 to 100,000, when the metal plating layer 15 is formed by electrolytic plating, the doping material is retained in the solid electrolyte layer 13, so that no current is generated due to dedoping, and electrons can be supplied by passing electricity on the surface of the solid electrolyte layer 13, and the metal plating layer 15 can be formed on the surface of the solid electrolyte layer 13 by electrolytic plating. Therefore, in the solid electrolytic capacitor 1, the cathode part 5 can be composed of two layers, the solid electrolyte layer 13 and the metal plating layer 15. That is, the cathode part 5 does not have a conductive layer between the solid electrolyte layer 13 and the metal plating layer 15. Therefore, the solid electrolytic capacitor 1 can be simplified in configuration compared to a cathode part including a solid electrolyte layer, a carbon paste layer, and a silver paste layer. As a result, the solid electrolytic capacitor 1 can be simplified in manufacturing.

Although the embodiments of the present invention have been described above, the present invention is not necessarily limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present invention.

In the above embodiment, the solid electrolyte layer 13 is formed by electrolytic polymerization. However, the solid electrolyte layer 13 may be formed by chemical oxidation polymerization.

In the above embodiment, an example has been described in which the capacitor structure 100 includes three solid electrolytic capacitors 1. However, the capacitor structure 100 may include two solid electrolytic capacitors 1, or may include four or more solid electrolytic capacitors 1.

The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

Example 1
The electrolytic capacitor was manufactured through the following procedure. First, an aluminum foil that had been subjected to surface enlargement treatment was prepared as an anode, and an insulator was formed at a position on the surface of the aluminum foil to separate the part to be the anode (anode terminal area) and the part to be the cathode (cathode formation area) for dividing them. The aluminum foil was immersed in an aqueous solution of ammonium adipate as a chemical conversion solution, and then a voltage was applied to the aluminum foil to cause an anodization reaction to proceed, forming a dielectric layer made of an aluminum oxide film on the surface layer of the aluminum foil. This resulted in a valve metal substrate having a dielectric layer formed on the aluminum foil.

Next, polypyrrole was formed on the valve metal substrate by electrolytic polymerization, and a solid electrolyte layer was formed on the valve metal substrate. Specifically, a polymerization solution was prepared that contained polypyrrole as a conductive polymer compound and polystyrene sulfonic acid with a number average molecular weight of 1200 as a doping material, and a solid electrolyte layer was formed on the dielectric layer of the substrate by polymerization.

Next, a metal plating layer was formed on the solid electrolyte layer. The metal plating layer was immersed in an electrolytic plating bath and a voltage was applied to form copper plating. In this way, a solid electrolytic capacitor was obtained.

Example 2
A solid electrolytic capacitor of Example 2 was produced in the same manner as in Example 1, except that the molecular weight of the doping material in the solid electrolyte layer was set to "5000".

Example 3
A solid electrolytic capacitor of Example 3 was produced in the same manner as in Example 1, except that the molecular weight of the doping material in the solid electrolyte layer was set to "7000."

(Comparative Example 1)
A solid electrolytic capacitor of Comparative Example 1 was produced in the same manner as in Example 1, except that the doping material for the solid electrolyte layer was butylnaphthalenesulfonic acid and the molecular weight of the doping material was "264."

(Comparative Example 2)
A solid electrolytic capacitor of Comparative Example 2 was produced in the same manner as in Example 1, except that the doping material for the solid electrolyte layer was anthraquinonesulfonic acid and the molecular weight of the doping material was "289."

(Comparative Example 3)
A solid electrolytic capacitor of Comparative Example 3 was produced in the same manner as in Example 1, except that the molecular weight of the doping material in the solid electrolyte layer was set to "920".

(Comparative Example 4)
A solid electrolytic capacitor of Comparative Example 4 was produced in the same manner as in Example 1, except that the molecular weight of the doping material in the solid electrolyte layer was set to "120,000."

(Evaluation of solid electrolytic capacitors)
The solid electrolytic capacitors obtained in Examples 1 to 3 and Comparative Examples 1 to 4 were subjected to an evaluation of plating appearance, an ESR measurement, and a peel test. In the plating appearance inspection, the solid electrolytic capacitors obtained in Examples 1 to 3 and Comparative Examples 1 to 4 were marked with "◯" when the metal plating layer was formed over the entire surface including the ends, marked with "△" when the metal plating layer was not formed on the ends, and marked with "X" when the metal plating layer was not formed or a defect (such as blistering) occurred in the metal plating layer.

To measure the ESR, an LCR meter was used to obtain the ESR at 100 kHz and compare it.

In the peel test, cellophane tape was applied to one side of the metal plating layer of the cathode part of the solid electrolytic capacitors obtained in Examples 1 to 3 and Comparative Examples 1 to 4, and then the cellophane tape was peeled off at a constant speed. If no plating components were attached to the cellophane tape, i.e., the metal plating layer had not peeled off, it was marked as "O", and if plating components were attached to the cellophane tape, i.e., at least a part of the metal plating had peeled off, it was marked as "X".

As shown in Table 1, the plating appearance of the solid electrolytic capacitors of Examples 1 to 3 was confirmed to be "good". The plating appearance of the solid electrolytic capacitors of Comparative Examples 1 to 3 was confirmed to be "△" or "x". The ESR of the solid electrolytic capacitors of Examples 1 to 3 was confirmed to be 60 mΩ to 90 mΩ. The ESR of the solid electrolytic capacitor of Comparative Example 1 could not be measured. The ESR of the solid electrolytic capacitor of Comparative Example 2 was confirmed to be 2 Ω, the solid electrolytic capacitor of Comparative Example 3 was confirmed to be 1.5 Ω, and the solid electrolytic capacitor of Comparative Example 4 was confirmed to be 700 mΩ. The solid electrolytic capacitors of Examples 1 to 3 were confirmed to have lower ESR than the solid electrolytic capacitors of Comparative Examples 2 to 4. The peel test of the solid electrolytic capacitors of Examples 1 to 3 was confirmed to be "good".

1, 1A, 1B, 1C... solid electrolytic capacitor, 3... anode portion, 5... cathode portion, 9... valve metal substrate, 9a... anode terminal area, 9b... cathode formation area, 11... dielectric layer, 13... solid electrolyte layer, 15... metal plating layer.

Claims (7)

a valve metal substrate having an anode terminal region and a cathode forming region and constituting an anode portion;
a cathode portion provided in the cathode formation region of the valve metal base,
the cathode portion has a solid electrolyte layer disposed on a surface of a dielectric layer provided on at least the cathode formation region of the valve metal base, and a metal plating layer disposed on the surface of the solid electrolyte layer,
the solid electrolyte layer includes a water-insoluble conductive polymer containing a doping material having a number average molecular weight of 1,000 to 100,000,
The solid electrolytic capacitor, wherein the metal plating layer is an electrolytic plating layer. The solid electrolytic capacitor according to claim 1, wherein the water-insoluble conductive polymer is polypyrrole or poly(3,4-ethylenedioxythiophene). The solid electrolytic capacitor according to claim 1 or 2, wherein the doping material is a sulfonic acid derivative. The solid electrolytic capacitor according to claim 3, wherein the doping material is a polystyrene sulfonic acid-based or phenol sulfonic acid-based material. The solid electrolytic capacitor according to claim 1 or 2, wherein the concentration of the doping material relative to the water-insoluble conductive polymer in the solid electrolyte layer is 1% or more and 200% or less. The solid electrolytic capacitor according to claim 1 or 2, wherein the metal plating layer is an electrolytic plating layer made of a copper layer. a preparation step of preparing a valve metal substrate;
a solid electrolyte layer forming step of forming a solid electrolyte layer on the valve metal substrate;
a plating layer forming step of forming a metal plating layer on the solid electrolyte layer by an electrolytic plating method,
In the solid electrolyte layer forming step, a polymerization treatment is performed including a step of immersing the valve metal base in a polymerization solution containing a water-insoluble conductive polymer containing a doping material having a number average molecular weight of 1,000 to 100,000, to form the solid electrolyte layer.

Images