CN1308980C - Solid electrolytic capacitor and manufacturing method thereof - Google Patents

Abstract

The thickness of the solid electrolyte formed in the cut-out portion and the shielding portion of the valve-acting metal porous substrate is larger than that of the other portions, so that the adhesion between the solid electrolyte formed on the dielectric film and the dielectric layer is improved, and the solid electrolytic capacitor having excellent stability in terms of the reflow heat resistance, the moisture load resistance, and the like, and the basic characteristics such as the capacitance, the dielectric loss (tg δ), the leakage current, and the short-circuit defect rate, is provided. In this solid electrolytic capacitor, a conductive polymer can be formed on the dielectric film by defining the time for impregnating the surface of the porous metal body having a valve action with the monomer-containing liquid and the oxidant-containing liquid, the time for volatilizing the solvent of the monomer-containing liquid, and the polymerization conditions after the impregnation with the oxidant-containing liquid within specific ranges.

Description

Solid electrolytic capacitor and manufacturing method thereof

technical field

The present invention relates to a solid electrolytic capacitor in which a conductive polymer is formed as a solid electrolyte on the surface of a porous metal substrate having valve action and a method for manufacturing the same.

In more detail, it relates to a method of manufacturing a high-performance solid electrolytic capacitor in which the thickness of the cut surface of the substrate and the solid electrolyte layer shielding the interface is thicker than other parts, especially the use of a monomer liquid and an oxidant liquid to manufacture such a solid electrolytic capacitor. capacitor.

Background technique

The basic components of a solid electrolytic capacitor 9 are shown in Figure 1. The manufacturing steps are usually to form a dielectric oxide film 2 on the anode substrate 1 made of a metal foil with a large specific surface area after corrosion treatment, as the outer surface of the solid electrolytic capacitor 9. The electrode forms a solid semiconductor layer (hereinafter referred to as electrolyte) 4, and further forms a conductive layer 5 such as a desired conductive paste. Secondly, this element can be single or laminated, connected by wires 6, 7, and the whole element is completely sealed with epoxy resin 8, etc., as a capacitor product, it is widely used in electrical products.

In recent years, along with the digitalization of electric appliances and the increase in speed of personal computers, small and high-capacity capacitors and capacitors with low impedance in the high-frequency range are required.

Examples of small and large-capacity capacitors include aluminum electrolytic capacitors and tantalum electrolytic capacitors. Aluminum electrolytic capacitors have the advantages of low cost and large capacity, but when using ion-conducting liquid electrolytes as electrolytes, they have the following problems: high impedance in the high-frequency range, and aging changes of the electrolyte with evaporation , resulting in deterioration of capacitance and deterioration of temperature characteristics.

On the other hand, in the case of tantalum electrolytic capacitors, manganese oxide is usually used as the electrolyte, and in manganese oxide formed mainly by thermal decomposition of manganese nitrate, the possibility of damage to the dielectric film during thermal decomposition is unavoidable, and, due to the specific resistance Higher, there is a problem of high impedance in the high frequency range.

Therefore, in order to solve these problems, it is proposed to use a conductive polymer with electronic conductivity as a solid electrolyte. For example, it is known to use an intrinsically conductive polymer having a conductivity in the range of 10 ^-3 to 10 ³ S/cm (JP-A-1-169914 (US Patent No. 4,803,596)), polyaniline (JP-A 61-240625 communique), polypyrrole (JP-A 61-241625 communique), polythiophene dielectric (JP-P2-15611 (US Patent No. 4910645 communique), polyisothiocyclane (JP-A 62-118511 communique ) and other polymers. For conductive polymers composed of these π-conjugated structures, compositions containing dopants are often used.

Recently, not only the addition of dopants but also the combined use of manganese dioxide (JP-A-6-101418 (US Pat. No. 4,959,753) and fillers (JP-A-9-320901) can also be used, for example.

As for the shape of the solid electrolyte, it is proposed to form the solid electrolyte on the entire surface of the aluminum foil by using the electrolytic oxidation polymerization as the starting point of the growth of the conductive polymer as the metal on the welded aluminum foil (JP-A-4-307917). In addition, it is recommended to alternately immerse in the monomer solution and the oxidant solution for 1 to 20 times, and then immerse in the oxidant solution for 5 minutes to 5 hours, so as to improve the polymerization efficiency.

Contents of the invention

In the manufacturing method of solid electrolytic capacitor in the past, above-mentioned solid electrolyte adopts conductive polymer, there are following problems: (1) when forming solid electrolyte layer, in the case of using monomer, due to the use of monomer and oxidizing agent The mixed liquid is polymerized into a polymer through the oxidation of the monomer in the mixed liquid and the oxidant in the mixed liquid. The polymer must be discarded, because the monomer in the mixed liquid cannot be effectively utilized, and the utilization rate of the material is extremely poor.

(2) Due to the denaturation of the mixed solution of the monomer and the oxidizing agent, the oxidation effect of the oxidizing agent is weakened, and the lifetime of the mixed solution is reduced, etc., resulting in instability in the formation process of the solid electrolyte layer.

(3) In the case of alternating immersion in two separate solutions of oxidant and monomer liquid, when the metal foil substrate impregnated in the monomer liquid is immersed in the oxidant solution for a specified time, the monomer is dissolved from the oxidant solution, and in the oxidant solution The polymerization of the monomers in the medium causes the life of the oxidant solution to deteriorate extremely. Similarly, if the metal foil substrate dipped in the oxidant solution is immersed in the monomer for a certain period of time, the life of the monomer solution will decrease accordingly.

(4) In preparing the mixed solution of the monomer and the oxidant, due to certain restrictions such as the concentration of the two and the mixing ratio, the concentration of the monomer cannot be set arbitrarily. In order to form a solid electrolyte layer with a desired thickness, the number of times of polymerization must increase.

(5) In the method of alternately impregnating the oxidizing agent and the monomer liquid and repeatedly polymerizing, the cleaning process is usually set after each polymerization process, but the operation and time required for each cleaning process not only reduces the solid electrolytic capacitor. The production efficiency of the element, and since the degree of polymerization between layers of the polymer solid electrolyte layer is reduced, the strength of the polymer solid electrolyte layer part is reduced, and there is room for improvement in the performance of the solid electrolytic capacitor.

(6) When cutting the metal porous body with valve action into the set shape, the cut surface (cut part) formed by it has only the dielectric layer formed in the chemical generation of the subsequent process, so this part has nothing to do with cutting. The portion other than the surface is weaker, and the adhesion amount of the solid electrolyte tends to decrease.

(7) The anode and cathode of the solid electrolytic capacitor are insulated. In order to prevent the solid electrolyte from being introduced into the vent hole, the solid electrolyte tends to be difficult to adhere sufficiently in the shielded part, causing the problem of a decrease in capacitance. In addition, since the shielded portion is easily subjected to considerable stress at the anode joint portion when the solid electrolytic capacitor element is stacked, a short circuit is likely to occur, resulting in a sharp increase in leakage current.

(8) The solid electrolyte of the conductive polymer is immersed in the organic polymer monomer solution and the oxidizing agent solution. In this formation method, it can be seen that the solid electrolyte is often adhered to the center of the aforementioned substrate (aluminum foil), On the other hand, the notch part and the masked part of the cut surface tend to be less adherent, and the balance of the adhesion state between the oxidizing agent and the monomer is disrupted, and a polymer with a certain performance tends not to be obtained.

As a result of earnest investigations by the present inventors in view of the above-mentioned problems, it can be confirmed that in the boundary range of the cutout and the shielding part, in order to increase the formation of the solid electrolyte, the solvent in the oxidizing agent solution on the substrate is slowly evaporated, and the remaining on the oxidizing agent The monomer is effectively polymerized. In this way, the obtained solid electrolytic capacitor has improved the adhesion between the solid electrolyte formed on the dielectric film and the dielectric layer, and its capacitance, dielectric loss (tgδ), leakage current, and short circuit It will become an excellent capacitor in terms of basic characteristics such as the defective rate, as well as the stability of characteristics such as reflow heat resistance and moisture load resistance.

When a solid electrolytic capacitor excellent in the above characteristics is immersed in an organic polymer monomer solution or dispersion (hereinafter simply referred to as a monomer-containing liquid) and an oxidizing agent solution or dispersion (hereinafter simply referred to as an oxidant-containing liquid), it can be found that this In order to reduce the dissolution of the monomer in the oxidizing agent-containing liquid or the elution of the oxidizing agent-containing liquid in the monomer-containing liquid, the immersion time in the oxidizing agent-containing liquid or the monomer-containing liquid should be controlled, and additionally added to the monomer-containing liquid After immersion in the drying process at the set temperature and time, in order to effectively control the polymerization time, it can be further confirmed that after alternately immersing and drying the polymerization process in the monomer-containing liquid and the oxidant-containing liquid, after repeating the set number of times, Finally, through the cleaning process, a solid electrolyte that maintains the excellent performance of interlayer overlap can be formed.

That is, the present invention provides the following solid electrolytic capacitor and its manufacturing method.

1. A solid electrolytic capacitor, the solid electrolytic capacitor is formed like this: on the dielectric film on the surface of the metal porous body substrate with valve action, a conductive polymer obtained by oxidative polymerization of an organic polymer monomer is set as a solid electrolyte, characterized in that,

The thickness of the solid electrolyte layer at the periphery of the substrate is greater than the thickness of the solid electrolyte layer at the center of the substrate, and the difference between the two is more than 0 μm and less than 200 μm.

2. A solid electrolytic capacitor, the solid electrolytic capacitor is formed like this: On the dielectric film on the surface of the metal porous body substrate surface with valve action cut into a predetermined shape, an organic polymer monomer obtained by oxidation polymerization of an oxidizing agent is arranged. A conductive polymer as a solid electrolyte, characterized in that,

The thickness of the solid electrolyte layer around the cut surface of the substrate is greater than the thickness of the solid electrolyte layer at the center of the substrate, and the difference between the two is more than 0 μm and less than 200 μm.

3. The solid electrolytic capacitor according to item 2 above, wherein

The thickness of the solid electrolyte layer around the cut surface of the substrate and the shielding boundary portion is greater than the thickness of the solid electrolyte layer at the central portion of the substrate.

4. A method for manufacturing a solid electrolytic capacitor, for manufacturing the solid electrolytic capacitor as described in any one of the preceding items 1 to 3, characterized in that,

The solid electrolyte layer is formed by solution chemical oxidation polymerization or gas phase chemical oxidation polymerization.

5. The method for manufacturing a solid electrolytic capacitor as described in item 4 above, wherein:

In the solution chemical oxidation polymerization, the metal substrate having a valve action having the dielectric film is alternately immersed in a liquid containing an organic polymer monomer and a liquid containing an oxidizing agent, and the above-mentioned dipping operation is repeated.

6. The solid electrolytic capacitor according to any one of items 1 to 3 above, wherein:

The metal porous body substrate having a valve action is in the form of a flat plate or a foil.

7. The solid electrolytic capacitor as described in item 6 above, wherein

The solid electrolyte is formed so that the longitudinal and transverse cross-sections of the central part of the porous metal substrate having the valve function are made into a gourd shape.

8. The solid electrolytic capacitor according to any one of items 1 to 3 above, wherein:

The metal porous body having a valve action is a single metal selected from aluminum, tantalum, niobium and titanium, or an alloy thereof.

9. The solid electrolytic capacitor according to any one of items 1 to 3 above, wherein

The organic high molecular monomer forming the conductive polymer is a compound containing a heteropentacyclic ring or a compound having an aniline skeleton.

10. The solid electrolytic capacitor according to item 9 above, wherein

The heteropentacyclic compound is a compound having a thiophene skeleton or a polycyclic sulfide skeleton.

11. The solid electrolytic capacitor according to item 10 above, wherein

Monomer compounds having a thiophene skeleton are: 3-ethylthiophene, 3-hexylthiophene, 3,4-dimethylthiophene, 3,4-methylenedihydroxythiophene, 3,4-ethylenedioxythiophene.

12. A multilayer solid electrolytic capacitor, characterized in that,

It is formed by laminating the solid electrolytic capacitors described in items 1 to 3 above in multiple layers.

13. A manufacturing method of a solid electrolytic capacitor, on the dielectric film on the surface of the metal porous body substrate with valve action, the organic polymer monomer is oxidatively polymerized by an oxidant as a solid electrolyte, characterized in that,

Repeat the step of immersing the organic polymer monomer-containing solution and the oxidizing agent-containing solution for no more than 5 minutes for 15 to 30 times to form a solid electrolyte layer that is thicker in the peripheral portion of the substrate than in the central portion.

14. The method of manufacturing a solid electrolytic capacitor according to the preceding item 13, wherein:

After immersing the metal substrate having a valve action in the liquid containing the organic polymer monomer, it is left in the air for 5 seconds to 15 minutes.

15. The method for manufacturing a solid electrolytic capacitor as described in item 13 above, wherein:

After immersing the metal substrate having a valve action in the aforementioned oxidant-containing liquid, it is left in the air for 10 seconds to 15 minutes.

16. The method of manufacturing a solid electrolytic capacitor according to item 14 or 15 above, wherein:

In the air, place it at a temperature of 0-60°C.

17. The method of manufacturing a solid electrolytic capacitor according to item 13 above, wherein:

There is also a cleaning operation after the polymerization step.

According to the present invention, the thickness of the solid electrolyte formed in the notch and the shielding portion is larger than that of other parts of the solid electrolytic capacitor, which improves the adhesion between the solid electrolyte formed on the dielectric film and the dielectric layer, and the capacitance, dielectric Basic characteristics such as electrical loss (tgδ), leakage current, and short-circuit defect rate, and stability in terms of reflow heat resistance and humidity load characteristics are excellent.

This solid electrolytic capacitor, in particular, specifies according to the method of the present invention: the impregnation time of the monomer-containing liquid and the oxidant-containing liquid on the surface of the metal porous body having a valve action, the volatilization time of the solvent in the monomer-containing liquid, and the immersion time of the solvent in the oxidant-containing liquid. According to the polymerization conditions after impregnation, a conductive polymer can be formed on the dielectric. At this time, alternate immersion in the monomer-containing liquid and the oxidizing agent-containing liquid for a predetermined number of times, and finally washing, can obtain a conductive polymer having a layered structure (thin layered structure or fibrous structure) and good properties.

Illustration

Fig. 1 is a sectional view of a capacitor element, Fig. 2 is a schematic longitudinal sectional view of the capacitor element material of Example 1, Fig. 3 is a sectional view of a solid electrolytic capacitor obtained by laminating the capacitor elements of Example 1, and Fig. 4 is a comparison A schematic longitudinal sectional view of the capacitor element material of Example 1.

Detailed Description of the Invention

The dielectric film on the surface of the substrate used in the present invention is usually formed by chemical generation treatment or the like of a porous metal body having valve action.

The production liquid used for chemical production, the production conditions such as the production voltage, etc., are confirmed and set to appropriate values through preliminary tests based on the necessary capacitance and withstand voltage for manufacturing solid electrolytic capacitors. In addition, during the production process, a shielding layer is generally provided in order to prevent the production solution from penetrating into the anode part of the solid electrolytic capacitor and to ensure insulation from the solid electrolyte (cathode part) formed in a later process.

As a masking material, general heat-resistant resins can be used, better ones are solvent-soluble or swelling heat-resistant resins, or their precursors, inorganic fine powders and compositions composed of celluloid resins (special Kaiping 11-80596 bulletin), etc., and the material is unlimited. Specific examples can be listed as follows: polyphenylene ink (PPS), polyether alum (DES), cyanate resin, fluororesin (tetrafluoroethylene, tetrafluoroethylene perfluoroalkyl vinyl ether copolymer, etc.), low molecular weight polyvinyl ether copolymer, etc. Imide and its dielectric and precursor, especially low molecular weight polyimide, polyether sulfone, fluororesin and its precursor are preferred.

Generally, the methods of forming a conductive polymer on a dielectric oxide film include: a conductive polymer layer formed by gas phase polymerization and a conductive polymer layer formed by electrolytic polymerization (JP-A-3-6217, etc.), After the organic polymer monomer is adhered to the dielectric oxide film, the solution chemical polymerization method of polymerizing in the oxidant solution (JP-11-251191, etc.), by switching the device, the setting of the feed point to the anode is changed each time. The electrolytic polymerization method (JP-A-11-283878, etc.) that averages the thickness of the conductive polymer layer for a given period of time. solution, and then dry it, and slowly increase the concentration of the oxidant solution on the substrate, using the solution chemical oxidation polymerization of organic polymer monomers with this process, or gas phase chemical oxidation polymerization. Especially preferred is solution chemical oxidation polymerization.

The present invention is based on gas-phase chemical oxidation polymerization, the partial pressure of the monomer (when the mixed gas is introduced into the dielectric film) and the gas pressure (when the pressure is adjusted to be introduced into the dielectric film) during the manufacture of the solid electrolyte, with the type or type of the compound substituent Although it varies depending on the type of solvent and the like, it is generally desirable to be within the range of 10 ^-3 to 10 atmospheres, more preferably within the range of 10 ^-2 to 5 atmospheres.

In addition, the reaction temperature during gas-phase chemical oxidation polymerization depends on the type and concentration of the compounds with their respective polymerization initiation energies, the partial pressure (pressure) of the monomers to be polymerized, etc., and is not particularly limited, but is generally selected at -70°C The temperature range of -250°C is preferably 0°C to 150°C, more preferably 15°C to 100°C.

According to the present invention, as shown in the following examples, an aluminum foil having a dielectric oxide film is immersed in, for example, an isopropanol (IPA) solution containing 3,4-ethylenedioxythiophene (EDT), and it is air-dried to almost remove After IPA, immerse in an aqueous solution containing about 20 (mass)% oxidant (ammonium persulfate), and heat at about 40°C for 10 minutes. In this way, the 3,4-ethylenedioxy In the polymer of thiophene, the thickness of the solid electrolyte layer around the substrate is larger than the thickness of the central portion.

The detailed reason for the variation in the thickness of the solid electrolyte layer is not necessarily clear, but it is considered that the moisture on the dielectric film with a large surface area tends to volatilize under the heating condition of about 40°C. When the cutting surface of the substrate is cut and the masking part moves, the water slowly evaporates from the oxidizing agent solution and becomes a high concentration. In order to contact the monomer and polymerize, a large amount of polymer adheres near the boundary of the cut and the masking part. , so that the thickness of the solid electrolyte layer around the substrate is greater than the thickness of the solid electrolyte layer at the center of the substrate.

That is, the solid electrolytic capacitor of the present invention is unique. The longitudinal and transverse cross-sections of the central part of the porous metal substrate having a valve action are gourd-shaped or loofah-shaped. The relationship between tension and osmotic pressure, the oxidant solution in the cut surface (cut part) and the shielding part is concentrated to a high concentration, so the polymer is precipitated here. In this way, the formation of the polymer at the end reduces the short circuit of the solid electrolytic capacitor. The defect rate and the leakage current become smaller, and the direction of obtaining better characteristics is moving forward.

The variation in the thickness of the solid electrolyte layer is obtained by immersing the metal substrate having a valve action in the monomer-containing liquid and the oxidant-containing liquid of the organic polymer, which varies with the formation conditions of the solid electrolyte such as the number of operations. In the range of good solid electrolytic capacitor characteristics, the difference between the maximum thickness and the minimum thickness of the longitudinal and transverse cross-sections of the central part of the substrate forming the solid electrolyte layer is 0 to 200 μm, preferably 0 to 180 μm, more preferably 0 to 150 μm .

Also, the solid electrolyte layer of the conductive polymer formed by the method of the present invention is considered to have a fibrous structure or a thin layer structure. In this structure, due to the overlapping effect between the polymer chains in a large range, the electronic transition is easy, which helps to improve the conductivity and improve characteristics such as low impedance.

In the solution chemical polymerization method, the monomer is adhered to the dielectric film with the micropores of the anode matrix, and in the presence of the conductive polymer dopant compound, oxidative polymerization is caused due to the action of the oxidant and the moisture in the air. The resulting polymer composition is used as the solid electrolyte to be formed on the surface of the dielectric. At this time, in order to form a good polymer composition, it is necessary to adjust the immersion time of the monomer-containing liquid and the oxidizing agent-containing liquid to control the amount of the monomer and oxidizing agent adhered to. For example, if the immersion time is too long, the polymerization reaction will be incomplete, and a low molecular weight polymer composition will be easily obtained. For another example, when the immersion time in the oxidant-containing liquid of unsaturated concentration is too long, the oxidant adhered on the metal foil substrate will be redissolved through the previous process including the drying process, and at the same time, due to the adhered monomer or The formed polymer will dissolve or flow out, so the formation of the polymer is delayed, and the oxidant-containing liquid is polluted by the effluent. The same situation occurs when dipping into a monomer-containing liquid.

In terms of phenomena, for example, there are: the oxidant-containing liquid due to low molecular weight components, the coloring of the monomer-containing liquid, the floating of the polymer, the tendency of the weight of the solid electrolyte formed by adhesion, the viscosity and specific gravity of the monomer-containing liquid, etc. Changes occur.

Therefore, in the method of the present invention, the monomer component and the oxidizing agent component in the containing liquid adhere to the dielectric surface of the metal foil substrate, and the time for immersing in the monomer containing liquid and the oxidizing agent containing liquid should not be too sufficient, no more than 5 minutes, preferably It is 0.1 second to 2 minutes, more preferably 1 second to 1 minute.

Also, in order to uniformly adhere the monomer to the surface of the dielectric and the polymer composition, after immersing in the monomer-containing liquid, it is necessary to leave it in the air for a certain period of time to allow the solvent to volatilize. This condition varies depending on the type of solvent, and it may be approximately OC or higher to a temperature up to the boiling point of the solvent. The standing time may also vary depending on the type of solvent, but it is approximately 5 seconds to 15 minutes. For example, in alcohol solvents, within 5 minutes is good. By setting this standing time, the monomer can be uniformly adhered to the surface of the dielectric, and contamination can be reduced during immersion into the oxidant-containing solution in the next process.

After immersing in the monomer-containing liquid and the oxidizing agent-containing liquid, the monomer is oxidatively polymerized by keeping it within a certain temperature range in the air for a set period of time. The polymerization temperature varies with the type of monomer. For example, in the case of pyrrole, it is better to be below 5°C, and in the case of thiophene series, it is necessary to be at 30-60°C.

The polymerization time depends on the adhesion amount of the monomer during immersion, because the adhesion amount varies with the concentration and viscosity of the monomer and oxidant-containing liquid, so it cannot be generalized. Generally, if the amount of one-time adhesion is less, the polymerization time can be shortened, and if the amount of one-time adhesion is large, a longer polymerization time is necessary. In the method of the present invention, the polymerization time for one time is 10 seconds to 15 minutes. , preferably 3 to 10 minutes.

According to the method of the present invention, the shape of the conductive polymer layer formed on the dielectric film can be confirmed as a laminar structure or a fibrous structure by electron micrographs.

It can be considered that the thin layer structure and fiber structure of the conductive polymer are important reasons for the increase in conductivity, which contribute to the expansion of the one-dimensional space of the polymer chain and the polymerization of the polymer chains in a large range. It has a good influence on the improvement of the conductivity of the polymer solid electrolyte and the improvement of capacitor characteristics such as low impedance.

In the method of the present invention, it is necessary to control the number of times of immersion in order to make the formed conductive polymer composition have a thickness that can withstand humidity, heat, stress, and the like. Each anode substrate in the aforementioned manufacturing process needs to be operated more than 15 times, preferably 20 to 30 times. Accordingly, a desired solid electrolyte layer can be easily formed.

The process of forming a solid electrolyte for a solid electrolytic capacitor is to alternately immerse the anode body in which a dielectric film is formed on a metal having a valve action in a liquid containing a monomer and a liquid containing an oxidant, dry it, and then repeatedly adhere the monomer and the oxidant alternately. , which is the process of chemical oxidation polymerization in air.

At this time, the humidity in the atmosphere is not less than 10% and not more than 80%. It is preferably at least 15% and at most 60%, more preferably at least 20% and at most 50%. Chemical oxidative polymerization is carried out under this condition, and the monomer or its dielectric is used as a repeating unit to form a conductive polymer layer.

The temperature and pressure in the atmosphere vary with the type of polymer composition, polymerization method, etc., and cannot be generalized, but usually the temperature is in the range of -70°C to 250°C, and the pressure is preferably below normal pressure.

The concentration of the monomer-containing liquid is 3 to 50 (mass) %, preferably 5 to 35 (mass) %, more preferably 10 to 25 (mass) %. The concentration of the oxidizing agent-containing liquid is 5 to 70 (mass) %, preferably 15 to 50 (mass) %. Also, the viscosity of the monomer-containing liquid and the oxidizing agent-containing liquid is at most 100 centipoise (cp), preferably at most 30 cp, more preferably from 0.6 to 10 cp.

According to the present invention, it can be clearly understood that the solid electrolyte of a conductive polymer having a layered structure (layered structure or fibrous structure) can be formed by alternately impregnating the monomer-containing liquid and the oxidizing agent-containing liquid, and for To expand the one-dimensional space of the polymer chains in the layer and to make the polymer chains overlap, it is not necessary to wash each time, and it is better to do it at the end. In this way, the residual excess (unreacted) monomer that has not been reacted in the polymerization process may be polymerized in the next process, and as a result, a solid electrolyte composed of a conductive polymer having a wide range of overlap can be formed. Layered structure.

The outer surface of the anode obtained by the method of the present invention is placed on the solid electrolyte covered with a thin layer structure or a fiber structure to form relatively continuous or independent spaces. Such a space reduces the influence of thermal stress, mechanical stress, etc. received in the capacitor manufacturing process such as the sealing process. Of course, it can be said that this advantageous structure is not only beneficial to the manufacturing process, but also can actually adapt to various stresses in the environment in which the capacitor is used.

According to the present invention, a good formation process of the solid electrolyte is that the metal anode foil having a valve action for forming the aforementioned dielectric film layer includes a process of immersing in a liquid containing an oxidant (containing liquid 1), and dipping in a liquid containing a monomer and doped Step of impurity-containing liquid (containing liquid 2). As this order, it can be dipped in the above-mentioned containing liquid 1, and then immersed in the above-mentioned containing liquid 2 (forward sequence), or the reverse order, that is, after the aforementioned metal anode foil with valve action is immersed in the above-mentioned containing liquid 2 , and further immersing in the above-mentioned containing liquid 1 step.

Perhaps as another embodiment, the above-mentioned anode foil may include a step of immersing in a solution containing an oxidizing agent and a dopant (containing solution 3), and a step of immersing in a solution containing a monomer (containing solution 4). In this case, it can be carried out in the process of dipping in the above-mentioned containing liquid 3 first, and then dipping the above-mentioned containing liquid 4 (forward sequence), or a reverse order manufacturing method can be adopted, that is, after the anode foil is dipped in the above-mentioned containing liquid 4, and then dipped in the above-mentioned containing liquid 4. The process of containing liquid 3 mentioned above. The above-mentioned containing liquid 1 to containing liquid 4 may be respectively in a suspended state, and the above-mentioned dipping step may be used instead of the coating operation.

For the solvents containing liquids 1 to 4, the same solvent can be used as needed, or different solvent series can also be used, and depending on the type of solvent, between containing liquid 1 and containing liquid 2, or between containing liquid 3 and containing liquid 4 In the process between them, a dry process can also be added, and the solvent can also be cleaned after the solid electrolyte is formed.

The valve-action metals that can be used in the present invention are single metals such as aluminum, tantalum, niobium, titanium, zirconium, magnesium and silicon, or their alloys. In terms of form, it may be a corroded product of a rolled foil or a porous formed body such as a fine powder sintered body.

Secondly, as the anode substrate, porous sintered bodies of these metals, plates (including laths, foils, etc.) that have been subjected to surface treatment such as corrosion, wires, etc., are preferably in the form of flat plates or foils, and the metals are porous. As a method for forming a dielectric oxide film on the surface of the body, a known method can be used. For example, when using tantalum powder sintered body, the anode is oxidized in phosphoric acid aqueous solution, and an oxide film can be formed on the sintered body.

For example, the thickness of metal foil having a valve action varies depending on the purpose of use, but generally a foil having a thickness of about 40 to 150 μm is used. , Also, the size and shape of the metal foil with valve action also varies with the application, but as a unit of a flat element, a rectangle with a width of 1 to 50 mm and a length of 1 to 50 mm is better, and it is preferably A rectangle with a width of about 2 to 15 mm and a length of about 2 to 25 mm.

In the formation of the solid electrolyte of the present invention, the oxidizing agent of usable aqueous solution series can be enumerated: persulfuric acid and its sodium salt, potassium salt, ammonium salt, cerium nitrate (IV), cerium nitrate (IV) ammonium, ferric sulfate ( III), iron (III) nitrate, iron (III) chloride, etc. In addition, examples of the oxidizing agent of the organic solvent series include ferrous salts of organic sulfonic acids, such as iron (III) dodecylphenylsulfonic acid, iron (III) p-tolylsulfonic acid, and the like. Examples of the organic solvent used here include monovalent alcohols such as r-butyrolactic acid and butanol and isopropanol. In addition, the concentration of the oxidant melt is preferably 5 to 50% by mass, and the temperature of the oxidant solution is preferably -15 to 60°C.

The conductive polymer used to form the solid electrolyte in the present invention is a polymer of organic polymer monomers having a π-electron conjugated structure, and its degree of polymerization is more than 2 and less than 2000, preferably more than 5 and less than 1000. Specific examples include compounds having a thiophene skeleton, compounds having a polycyclic sulfide skeleton, compounds having a pyrrole skeleton, compounds having a furan skeleton, compounds having an aniline skeleton, and the like. These conductive polymers The structures shown by them are used as repeating units, but the conductive polymer is not limited to these.

Examples of monomeric compounds having a thiophene skeleton include 3-methylthiophene, 3-ethylthiophene, 3-propylthiophene, 3-butylthiophene, 3-pentylthiophene, 3-hexylthiophene, and 3-heptylthiophene. Thiophene, 3-octylthiophene, 3-nonylthiophene, 3-decylthiophene, 3-fluorothiophene, 3-chlorothiophene, 3-bromothiophene, 3-cyanothiophene, 3,4-di Methylthiophene, 3,4-diethylthiophene, 3,4-butenylbromothiophene, 3,4-methylenedihydroxythiophene, 3,4-ethylenedioxythiophene and other dielectrics. These compounds are generally commercially available compounds, or can be prepared by known methods (for example, Synthetic Metals Journal, 1986, Vol. 15, p. 169), but are not limited thereto.

Also, as specific examples of monomer compounds having a polycyclic sulfide skeleton, those having a skeleton of 1,3-dihydroxy polycyclic sulfide (alias 1,3-hydroxy [c]thiophene) can be used. The compound is a compound having a 1,3-dihydroxynaphtho[2,3-c]thiophene skeleton. Also, compounds having a 1,3-dihydroxyanthracene[2,3-c]thiophene skeleton and compounds having a 1,3-dihydroxybutyro[2,3-c]thiophene skeleton can be cited, and these can also be obtained according to A known method, for example, the method disclosed in JP-A-8-3156.

Also, compounds having a 1,3-dihydroxynaphtho[1,2-c]thiophene skeleton, 1,3-dihydroxyphenanthrene[2,3-c] dielectric, 1,3-dihydroxytriphenyl [2,3-c]thiophene skeleton compound, 1,3-dihydroxybenzo[a]anthracene[7,8-c]thiophene dielectric, etc.

The fused ring can use any compound containing nitrogen or nitrogen oxide, such as: 1,3-dihydroxythian [3,4]-b]quinoline or 1,3-dihydroxythian [3,4-b ]quinoxaline-4-oxide, 1,3-dihydroxythian[3,4-b]quinoxaline-4,9-dioxide, etc., but not limited to these.

Monomer compounds having a hydroxyl skeleton include 3-methylpyrrole, 3-ethylpyrrole, 3-butylpyrrole, 3-pentylpyrrole, 3-hexylpyrrole, 3-heptylpyrrole, and 3-phanylpyrrole. Pyrrole, 3-nonylpyrrole, 3-decylpyrrole, 3-fluoropyrrole, 3-chloropyrrole, 3-bromopyrrole, 3-cyanopyrrole, 3,4-dimethylpyrrole, 3,4 -diethylpyrrole, 3,4-butenepyrrole, 3,4-methylenedihydroxypyrrole, 3,4-ethylenedioxypyrrole and other dielectrics. These compounds are commercially available or can be prepared by known methods, but the present invention is not limited thereto.

Monomer compounds having a furan skeleton include: 3-methylfuran, 3-ethylfuran, 3-propylfuran, 3-butylfuran, 3-pentylfuran, 3-hexylfuran, 3-heptylfuran , 3-octylfuran, 3-nonylfuran, 3-decylfuran, 3-fluorofuran, 3-chlorofuran, 3-bromofuran, 3-cyanofuran, 3,4-dimethylfuran Furan, 3,4-diethylfuran, 3,4-butenefuran, 3,4-methylenedihydroxyfuran, 3,4-ethylenedioxyfuran and other dielectrics. These compounds are commercially available or can be prepared by known methods, but the present invention is not limited thereto.

Monomer compounds having an aniline skeleton include: 2-methylaniline, 2-ethylaniline, 2-propylaniline, 2-butylaniline, 2-pentylaniline, 2-hexylaniline, 2-heptylaniline , 2-octylaniline, 2-nonylaniline, 2-decylaniline, 2-fluoroaniline, 2-chloroaniline, 2-bromoaniline, 2-cyanoaniline, 2,5-dimethylaniline , 2,5 diethylaniline, 2,3 butene aniline, 2,5-methylene dihydroxyaniline, 2,3-ethylenedioxyaniline and other dielectrics. These compounds are commercially available or can be prepared by known methods, but the present invention is not limited thereto.

Among these compounds, compounds having a thiophene skeleton or a polycyclic sulfide skeleton are preferable, and 3,4-ethylenedioxythiophene (EDT) is particularly preferably 1,3-dihydroxyisothiocyclane.

Also, as the solvent for the aforementioned organic polymer monomer, it is better to use the following monovalent alcohols (methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, etc.), The concentration of the monomer in the monomer solution is not particularly limited, and any concentration can be selected.

There are no particular restrictions on the polymerization conditions of the compounds selected from the above-mentioned compound groups, and it can be easily carried out through simple experiments to confirm the pre-selected conditions.

A solid electrolyte can also be formed as a copolymer by using compounds selected from the above-mentioned monomer compound group in combination. In this case, the composition ratio of the polymerizable monomer depends on the polymerization conditions and the like, and a good composition ratio and polymerization conditions can be confirmed by a simple test.

For example, the EDT monomer and the oxidizing agent are in a satisfactory solution state, and the method can be formed by coating it on the oxide film layer of the metal foil separately or together (Japanese Unexamined Patent Publication No. 2-15611, Kaiping No. 10-32145 Bulletin).

Use better 3 in the present invention, 4-ethylenedioxythiophene (EDT), it is easily soluble in above-mentioned monovalent alcohols, because can not dissolve well with water as a whole, when contacting with high-concentration oxidizing agent aqueous solution , EDT is well polymerized at its interface to form a conductive polymer solid electrolyte layer with a fibrous structure or a thin layer structure.

For the solution or solid electrolyte used in the production method of the present invention, the solvent used for cleaning after its formation can be, for example: tetraoxyfuran (THF) or dioxane, ethers such as diethyl ether, ketones such as acetone and methyl ethyl ketone; Aprotic polar solvents such as methyl formamide, acetonitrile, benzonitrile, N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), esters such as ethyl acetic acid and butyl acetic acid, chloroform, methylene chloride nitromethane, nitroethane, nitrobenzene and other nitro compounds; methanol, ethanol, propanol and other alcohols, formic acid, acetic acid, propionic acid and other organic acids, available The anhydrous acid of the organic acid (for example, anhydrous acetic acid, etc.), and water or these mixed solvents, ideally water, alcohols and ketones or their mixed series are desirable.

In the conductive polymer of the present invention, an arylsulfone acid-based dopant is used. For example, salts of phenylsulfonic acid, tolylsulfonic acid, naphthalenesulfonic acid, anthrasulfonic acid, and anthraquinonesulfonic acid can be used as the raw material of the dopant.

The conductivity of the solid electrolyte produced in this way is in the range of about 0.1-200 s/cm, preferably in the range of about 1-150 s/cm, more preferably in the range of about 10-100 s/cm. On the formed conductive polymer composition layer, in order to make good electrical contact with the cathode lead terminal, it is better to set a conductive layer, for example, to form a solid conductive paste, and to form a conductive resin film by electroplating or metal evaporation.

The solid electrolytic capacitor element obtained in this way is multi-layer laminated and connected to the end of the layer to achieve the desired capacitance. For example, it is packaged by resin molds, resin boxes, metal outer packaging boxes, and resin impregnation. Become a capacitor product for various purposes.

Detailed ways

Hereinafter, examples are given to describe the present invention in detail. According to the following examples, the present invention is not limited in any way.

Example 1

Cut the corroded aluminum foil into 3 mm in the short axis direction x 10 mm in the long axis direction, divide the long axis direction into 4 mm and 5 mm parts, apply polyimide solution around the 1 mm wide sides on both sides, and make a masking layer after drying. A 3 mm x 4 mm portion of the aluminum foil formed by the etching was applied with a voltage of 13 volts in an aqueous solution of 10 (mass) % ammonium oxalate to form a dielectric oxide film on the cut portion. Next, immerse the 3 mm × 4 mm portion of the aluminum foil in a solution containing 5 g of 3,4-ethylenedioxythiophene (manufactured by Bayer AG) dissolved in 1.2 mol/L of isopropanol (IPA) for 5 seconds, and place it in Dry at room temperature for 5 minutes, and then immerse in an aqueous solution of ammonium persulfate for 5 seconds. The preparation of the suspension solution is to apply 0.07 (mass)% of sodium 2-anthraquinone sulfonic acid to a 2mol/L aqueous solution of ammonium persulfate . Next, place the aluminum foil in the atmosphere at 40°C for 10 minutes to carry out oxidative polymerization, and then perform the dipping process and polymerization process 25 times as a whole, so that a conductive polymer solid electrolyte layer is formed on the outer surface of the corroded aluminum foil. . The resulting polymer (3,4-dioxythiophene) was washed in warm water at 50°C and then dried at 100°C for 30 minutes to form a solid electrolyte layer.

Use a film thickness gauge (manufactured by Peacock, DG-205 (accuracy 3 μm)] to clamp the aluminum foil, slowly push it into the measuring part of the film thickness gauge, and measure the thickness. ) was 260 μm, the thickness of the constricted part in the center was 210 μm, and the difference (h1-h2) in film thickness was 50 μm.

Next, as shown in FIG. 3, carbon paste and silver paste are adhered to the conductive polymer composition layer where the above-mentioned aluminum foil is formed, and the above-mentioned four pieces of aluminum foil are laminated and connected to the cathode terminal. In addition, the anode terminal was connected by welding at the portion where the conductive polymer composition layer was not formed. Furthermore, after sealing this element with epoxy resin, it aged by applying a rated voltage at 125 degreeC for 2 hours, and completed 30 capacitors in total.

For these 30 capacitor elements, the initial characteristics measured were: capacitance and loss factor (tgδ×100%) at 120 Hz, impedance at resonance frequency and leakage current thereof. However, the leakage current is measured after applying the rated voltage for 1 minute. Table 1 shows the average value of these measured values, the defective rate and the number of short-circuited components when the leakage current of 0.59μA (0.002CV) or more is regarded as a defective product. The average value of the leakage current here is the calculated value after excluding defective products. . Table 2 shows the results of the reflow test and the subsequent humidity resistance test. However, when the leakage current value in the humidity resistance test exceeds 11.8μA (0.04CV), it is considered a defective product. Here, the reflow test was carried out at a temperature range of 230° C. for 30 seconds, and the humidity resistance test was performed at a high temperature and high humidity of 85° C. and 85% RH (relative humidity) for 240 hours.

Example 2

In embodiment 1, except that ammonium persulfate is replaced by ferrous sulfate, and 3.4-ethylenedioxythiophene is replaced by dihydroxyisothiocyclane, the rest is the same as embodiment 1, and 30 capacitors are completed.

As in Example 1, the thickness of the protruding portion of the solid electrolyte layer was measured to be 250 μm, the thickness of the constricted portion of the central portion was 200 μm, and the film thickness difference (h1-h2) was 50 μm.

Tables 1 and 2 show the results of the same characteristic evaluation of the obtained capacitor element as in Example 1.

Example 3

In Example 1, divide by pyrrole instead of 3.4-E=oxythiophene, then after dipping in pyrrole solution, dry at 3C for 5 minutes, then dip in oxidizing agent solution, polymerize at 5C for 10 minutes, and in addition Implementation 1 Similarly, 30 capacitors are completed.

In the same manner as in Example 1, the thickness of the protruding portion of the solid electrolyte layer was 280 μm, the thickness of the central concave portion was 210 μm, and the difference in film thickness (h1-h2) was 70 μm.

The characteristics of the obtained capacitor were evaluated in the same manner as in Example 1, and the results are shown in Table 1 and Table 2. In Example 1, divide by pyrrole instead of 3.4-E=oxythiophene, then after dipping in pyrrole solution, dry at 3C for 5 minutes, then dip in oxidizing agent solution, polymerize at 5C for 10 minutes, and in addition Implementation 1 Similarly, 30 capacitors are completed.

In the same manner as in Example 1, the thickness of the protruding portion of the solid electrolyte layer was 280 μm, the thickness of the central concave portion was 210 μm, and the difference in film thickness (h1-h2) was 70 μm.

The characteristics of the obtained capacitor were evaluated in the same manner as in Example 1, and the results are shown in Table 1 and Table 2.

Example 4

In Example 1, 30 capacitors were completed in the same manner as in Example 1 except that furan was used instead of 3.4-ethylenedioxythiophene.

In the same manner as in Example 1, the thickness of the protruding portion of the solid electrolyte layer was 260 μm, and the thickness of the central concave portion was 210 μm, and the film thickness difference (h1-h2) was 60 μm.

The characteristics of the obtained capacitor were evaluated in the same manner as in Example 1, and the results are shown in Table 1 and Table 2.

Example 5

In Example 1, 30 capacitors were completed in the same manner as in Example 1, except that aniline was used instead of 3.4-ethylenedioxythiophene. In the same manner as in Example 1, the thickness of the protruding part of the solid electrolyte layer was 270 μm, the thickness of the central concave part was 210 μm, and the film thickness difference (h1-h2) was 60 μm.

The characteristics of the obtained capacitor element were evaluated in the same manner as in Example 1, and the results are shown in Tables 1 and 2.

Comparative example 1

3.4-Ethylenedioxythiophene (manufactured by Bayer AG) was dissolved in 75% IPA solution of ferric dodecylphenylsulfone at an equimolar amount, and the solution was dripped or dipped on the aluminum foil prepared in Example 1. Then, this aluminum foil was left in the air at 40°C for about 60 minutes to carry out oxidative polymerization.

The aluminum foil was clamped with a film thickness gauge (DG-205 (accuracy: 3 μm) manufactured by Peacock Co., Ltd.), and pushed into the measurement site of the film thickness gauge to measure the thickness.

As a result, as shown in the schematic diagram of FIG. 4 , the peripheral thickness (h3) was 230 μm, the central protrusion thickness (h4) was 240 μm, and the film thickness difference (h3-h4) was -10 μm.

Thirty capacitors were completed in the same manner as in Example 1 except that the polymerization method was changed. Evaluation of the characteristics of these capacitor elements was carried out in the same manner as in Example 1, and the results are shown in Tables 1 and 2.

Table 1 initial characteristics Capacitance μF Loss factor% Impedance mΩ Leakage current μA Defective rate Short circuit number Example 1 51.9 0.603 0.008 0.03 0/30 0 Example 2 50.3 0.635 0.013 0.05 0.30 0 Example 3 50.9 0.624 0.012 0.06 0/30 0 Example 4 49.8 0.653 0.017 0.07 0/30 0 Example 5 49.6 0.678 0.019 0.09 0/30 0 Comparative example 1 40.1 1.658 0.045 0.95 4/30 4

Table 2 Reflow test Humidity test defective product Short circuit number leakage current defective product Short circuit number Example 1 0/30 0 0.49 0/30 0 Example 2 0.30 0 0.54 0.30 0 Example 3 0/30 0 0.59 0/30 0 Example 4 0/30 0 0.57 0/30 0 Example 5 0/30 0 0.61 0/30 0 Comparative example 1 3/26 3 2.10 4/30 1

From the results of Examples 1 to 5 and Comparative Example 1, it can be seen that the metal multi-body substrate with valve action is a solid electrolytic capacitor whose peripheral solid electrolyte layer has a larger thickness than the solid electrolyte layer at the center of the substrate. It is excellent in basic characteristics such as capacitance, dielectric loss (tgδ), leakage current, and short-circuit defect rate, and in stability such as reflow heat resistance and moisture resistance load characteristics.

Example 6

Thirty capacitors were produced in the same manner as in Example 1 except that the prepared solid electrolyte was immersed in an oxidizing agent solution for 3 minutes. The characteristic evaluation of these capacitor elements was carried out in the same manner as in Example 1, and the results are shown in Tables 3 and 4.

Example 7

Thirty capacitors were produced in the same manner as in Example 1 except that the prepared solid electrolyte was immersed in an oxidizing agent solution for 4 minutes. The characteristic evaluation of these capacitor elements was carried out in the same manner as in Example 1, and the results are shown in Tables 3 and 4.

Example 8

30 capacitors were produced in the same manner as in Example 1 except that the prepared solid solution was immersed in the monomer solution for 4 minutes. The characteristic evaluation of these capacitor elements was carried out in the same manner as in Example 1, and the results are shown in Tables 3 and 4.

Example 9

30 capacitors were fabricated in the same manner as in Example 1 except that the solid electrolyte impregnation step and the polymerization step were performed 20 times. The characteristic evaluation of the characteristics of these capacitor elements was carried out in the same manner as in Example 1, and the results are shown in Tables 3 and 4.

Example 10

30 capacitors were produced in the same manner as in Example 1 except that the production of the solid electrolyte, the impregnation process, and the polymerization process were performed 28 times. Evaluation of the characteristics of these capacitor elements was performed in the same manner as in Example 1, and the results are shown in Tables 3 and 4.

Example 11

Dielectric film is formed in the same manner as in Example 1, and the aluminum foil 3mm * 4mm part that is corroded is immersed in the suspension aqueous solution of ammonium persulfate for 5 seconds. Sodium sulfonic acid was applied to 1.5mol/L ammonium persulfate aqueous solution, and then placed in a polymerization tank heated at 60°C. The gas of 3.4-ethylenedioxythiophene generated by heating at 80°C is introduced into the polymerization tank together with nitrogen to carry out gas phase thickening oxidation polymerization. Then place the corroded aluminum foil in the air at 40°C to dry for 10 minutes, and then perform the impregnation process and polymerization process of the oxidant 15 times, so that a conductive polymer solid electrolyte is formed on the surface of the corroded aluminum foil. layer. Finally, the resulting polymer was washed in warm water at 70°C, and then dried at 100°C for 30 minutes to form a solid electrolyte.

As in Example 1, the thickness (h1) of the protruding part of the solid electrolyte layer was 180 µm, the thickness (h2) of the central recessed part was 130 µm, and the film thickness difference (h1-h2) was 50 µm.

Next, similarly to Example 1, 30 capacitors were produced. Evaluation of the characteristics of these capacitor elements was performed in the same manner as in Example 1, and the results are shown in Tables 3 and 4.

Comparative example 2

The impregnation process and the polymerization process were performed 10 times to produce a solid electrolyte. Except for this, 30 capacitors were fabricated in the same manner as in Example 1. Evaluation of the characteristics of these capacitor elements was performed in the same manner as in Example 1, and the results are shown in Tables 3 and 4.

Comparative example 3

Immerse in an oxidant solution for 10 minutes to make a solid electrolyte. Except for this, 30 capacitors were fabricated in the same manner as in Example 1. Evaluation of the characteristics of these capacitor elements was performed in the same manner as in Example 1, and the results are shown in Tables 3 and 4.

Comparative example 4

The impregnation step and the polymerization step are carried out by washing each time to obtain a solid electrolyte. Except for this, 30 capacitors were fabricated in the same manner as in Example 1. Evaluation of the characteristics of these capacitor elements was performed in the same manner as in Example 1, and the results are shown in Tables 3 and 4.

Comparative Example 5

The polymerization humidity was 70°C, and it was made into a solid electrolyte. Except for this, 30 capacitors were fabricated in the same manner as in Example 1. Evaluation of the characteristics of these capacitor elements was performed in the same manner as in Example 1, and the results are shown in Tables 3 and 4.

Comparative example 6

Immerse in the monomer solution for 10 minutes to make a solid electrolyte. Except for this, 30 capacitors were fabricated in the same manner as in Example 1. Evaluation of the characteristics of these capacitor elements was performed in the same manner as in Example 1, and the results are shown in Tables 3 and 4.

Comparative Example 7

Immerse in the oxidant solution for 7 minutes to make a solid electrolyte. Except for this, 30 capacitors were fabricated in the same manner as in Example 1. Evaluation of the characteristics of these capacitor elements was performed in the same manner as in Example 1, and the results are shown in Tables 3 and 4.

Comparative Example 8

Immerse in the monomer solution for 7 minutes to make a solid electrolyte. Except for this, 30 capacitors were fabricated in the same manner as in Example 1. Evaluation of the characteristics of these capacitor elements was performed in the same manner as in Example 1, and the results are shown in Tables 3 and 4.

Comparative Example 9

The impregnation process and the polymerization process were performed 40 times to produce a solid electrolyte. Except for this, 30 capacitors were fabricated in the same manner as in Example 1. Evaluation of the characteristics of these capacitor elements was performed in the same manner as in Example 1, and the results are shown in Tables 3 and 4.

table 3 initial characteristics Capacitance μF Loss factor% Impedance mΩ Leakage current μA Defective rate Short circuit number Example 6 51.7 0.62 0.009 0.03 0/30 0 Example 7 50.3 0.63 0.013 0.04 0.30 0 Example 8 51.6 0.61 0.009 0.03 0/30 0 Example 9 50.2 0.62 0.010 0.03 0/30 0 Example 10 51.9 0.65 0.008 0.08 0/30 0 Example 11 49.3 0.84 0.019 0.31 0/30 0 Comparative example 2 42.1 0.76 0.035 0.80 3/30 3 Comparative example 3 40.8 0.77 0.027 0.69 4/30 4 Comparative example 4 30.7 0.79 0.030 0.89 3/30 3 Comparative Example 5 36.9 0.74 0.035 0.95 5/30 5 Comparative example 6 45.2 0.69 0.024 0.11 2/30 1 Comparative Example 7 49.7 0.72 0.032 0.73 2/30 1 Comparative Example 8 48.0 0.69 0.022 0.10 1/30 1 Comparative Example 9 51.7 0.78 0.010 0.85 4/30 2

* Loss factor (%) = tanδ × 100 (%)

Table 4 Reflow test Humidity test defective product Short circuit number leakage current defective product Short circuit number Example 6 0/30 0 0.53 0/30 0 Example 7 0.30 0 0.60 0.30 0 Example 8 0/30 0 0.46 0/30 0 Example 9 0/30 0 0.71 0/30 0 Example 10 0/30 0 0.85 0/30 0 Example 11 0/30 0 0.87 0/30 0 Comparative example 2 1/28 1 2.10 1/27 1 Comparative example 3 1/29 0 1.75 2/28 1 Comparative example 4 2/27 1 3.57 4/25 2 Comparative Example 5 2/28 1 3.45 3/26 2 Comparative Example 6 1/28 0 1.02 2/27 1 Comparative Example 7 3/29 1 1.02 3/28 2 Comparative Example 8 1/28 0 1.52 2/28 1 Comparative Example 9 2/28 1 2.12 3/27 2

Tables 3 to 4 have shown the results of Examples 6 to 10 and Comparative Examples 2 to 9, and from Tables 1 and 2 of the results shown in previous Examples 1 to 5 and Comparative Example 1, it is known that: with various monomers The immersion time of the solution is not more than 5 minutes (Example 1: 3,4-ethylenedioxythiophene, Example 2: dihydroxyisothiocyclane, Example 3: pyrrole, Example 4: furan, Example 5: Aniline, the respective immersion time is 5 seconds, embodiment 8: 3,4-ethylenedioxythiophene, the immersion time is 4 minutes), the immersion time in the oxidizing agent solution is no more than 5 minutes (embodiment 6～7), in single Alternate immersion in solid solution and acid solution, repeated 15 to 30 times (embodiments 9 to 10), obtained in capacitance, dielectric loss (tgδ), impedance, initial basic characteristics of leakage current, reflow heat resistance test and moisture resistance For capacitors with excellent stability in the load test, when the immersion time in the monomer solution exceeds 5 minutes (Comparative Examples 6, 8), when the immersion time in the oxidizing agent solution exceeds 5 minutes (Comparative Examples 6, 7), in When the number of alternate immersions in the oxidant solution and in the acid solution is small (Comparative Example 2) or too many (Comparative Example 9), by alternate immersion, washing is performed after each polymerization (Comparative Example 4), the polymerization When the temperature exceeds 60° C. (Comparative Example 5), their initial basic characteristics, reflow heat resistance and moisture load resistance characteristics are not stable.

Claims (19)

1. A solid electrolytic capacitor, the solid electrolytic capacitor has: as a solid electrolyte provided on a dielectric film on the surface of a porous metal substrate having a valve action, a conductive polymer obtained by oxidizing and polymerizing an organic polymer monomer through an oxidizing agent body, characterized in that, The thickness of the solid electrolyte layer at the periphery of the substrate is greater than the thickness of the solid electrolyte layer at the center of the substrate, and the difference between the two is more than 0 μm and less than 200 μm. 2. A solid electrolytic capacitor, the solid electrolytic capacitor has: the organic polymer monomer is oxidized by an oxidizing agent as a solid electrolyte arranged on a dielectric film on the surface of a metal porous body substrate surface cut into a predetermined shape with valve action The conductive polymer obtained by polymerization is characterized in that, The thickness of the solid electrolyte layer around the cut surface of the substrate is greater than the thickness of the solid electrolyte layer at the center of the substrate, and the difference between the two is more than 0 μm and less than 200 μm. 3. The solid electrolytic capacitor according to claim 2, wherein, The thickness of the solid electrolyte layer around the cut surface of the substrate and the shielding boundary portion is greater than the thickness of the solid electrolyte layer at the central portion of the substrate. 4. A method for manufacturing a solid electrolytic capacitor, used to manufacture the solid electrolytic capacitor according to any one of claims 1 to 3, characterized in that, The solid electrolyte layer is formed by solution chemical oxidation polymerization or gas phase chemical oxidation polymerization. 5. The manufacture method of solid electrolytic capacitor as claimed in claim 4, is characterized in that, In the solution chemical oxidation polymerization, the metal substrate having a valve action having the dielectric film is alternately immersed in a liquid containing an organic polymer monomer and a liquid containing an oxidizing agent, and the above-mentioned dipping operation is repeated. 6. The solid electrolytic capacitor according to any one of claims 1 to 3, wherein: The metal porous body substrate having a valve action is in the form of a flat plate or a foil. 7. The solid electrolytic capacitor as claimed in claim 6, wherein, The solid electrolyte is formed so that the longitudinal and transverse cross-sections of the central part of the porous metal substrate having the valve function are made into a gourd shape. 8. The solid electrolytic capacitor according to any one of claims 1 to 3, wherein: The metal porous body having a valve action is a single metal selected from aluminum, tantalum, niobium and titanium, or an alloy thereof. 9. The solid electrolytic capacitor according to any one of claims 1 to 3, wherein The organic polymer monomers that form conductive polymers are heteropentacyclic compounds or have aniline skeletons 9. The solid electrolytic capacitor according to any one of claims 1 to 3, wherein The organic high molecular monomer forming the conductive polymer is a compound containing a heteropentacyclic ring or a compound having an aniline skeleton. 10. The solid electrolytic capacitor according to claim 9, wherein, The heteropentacyclic compound is a compound having a thiophene skeleton or a polycyclic sulfide skeleton. 11. The solid electrolytic capacitor according to claim 10, wherein, Monomer compounds having a thiophene skeleton are: 3-ethylthiophene, 3-hexylthiophene, 3,4-dimethylthiophene, 3,4-methylenedihydroxythiophene, 3,4-ethylenedioxythiophene. 12. A multilayer solid electrolytic capacitor, characterized in that, It is formed by laminating the solid electrolytic capacitors according to claims 1 to 3 in multiple layers. 13. A manufacturing method of a solid electrolytic capacitor, on the dielectric film on the surface of the metal porous body substrate with valve action, the organic polymer monomer is oxidatively polymerized by an oxidant as a solid electrolyte, characterized in that, Repeat the step of immersing the organic polymer monomer-containing liquid and the oxidizing agent-containing liquid 15 to 30 times for no more than 5 minutes each time, to form a solid electrolyte layer whose thickness is greater at the periphery of the substrate than at the center. 14. The manufacturing method of solid electrolytic capacitor as claimed in claim 13, is characterized in that, After immersing the metal substrate having a valve action in the liquid containing the organic polymer monomer, it is left in the air for 5 seconds to 15 minutes. 15. The manufacturing method of solid electrolytic capacitor as claimed in claim 13, is characterized in that, After immersing the metal substrate having a valve action in the aforementioned oxidant-containing liquid, it is left in the air for 10 seconds to 15 minutes. 16. The manufacturing method of solid electrolytic capacitor as claimed in claim 14 or 15, it is characterized in that, In the air, place it at a temperature of 0-60°C. 17. The manufacturing method of solid electrolytic capacitor as claimed in claim 13, is characterized in that, A washing step is also provided after the polymerization step. 18. The manufacturing method of solid electrolytic capacitor as claimed in claim 4, is characterized in that, Gas-phase chemical oxidation polymerization includes a step of forming an organic polymer monomer into a mixed gas and then introducing it onto a dielectric film, or a step of introducing an organic polymer monomer onto a dielectric film after pressure adjustment.

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