JPH09306793A - Manufacture of capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To largely improve the characteristics of leakage current and breakdown voltage by providing the forming stem in low current density before forming a solid electrolytic layer such as conductive polymer. SOLUTION: Sintered valve metal is prepared. First formation is conducted by first current density to form an oxide film dielectric layer on the metal. Then, second formation is conducted by lower second current density than the first density continued to the first step for the valve metal after the first step, and the defect part of the dielectric layer is repaired. A cathode is disposed oppositely on the metal, and a capacitor is manufactured. After the second step, before aging step, a conductive polymer layer is formed by polymerization adjacent to the dielectric layer. Thus, a solid electrolytic capacitor having excellent characteristics of a leakage current and a breakdown voltage can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a capacitor, and more particularly to a method for manufacturing a highly reliable solid electrolytic capacitor using a conductive polymer or the like as a solid electrolyte.

[0002]

2. Description of the Related Art A conventional electrolytic capacitor, for example, an aluminum electrolytic capacitor, has an aluminum oxide layer, which is a dielectric material, provided on an etched porous aluminum foil having a large specific surface area, and is used as a separator paper between it and a cathode foil. It has a structure in which a liquid electrolyte is impregnated.

However, such an electrolytic capacitor has a disadvantage that the resistance increases remarkably in a high frequency region and the impedance increases because it functions by the ionic conduction of the electrolytic solution.

Therefore, in recent years, attempts have been made to replace this electrolytic solution with a solid electrolyte. Such a solid electrolytic capacitor has a structure in which a solid electrolyte layer is adhered to an oxide film dielectric layer of a valve metal such as aluminum or tantalum. For example, a heterocyclic compound pyrrole is chemically oxidized with an oxidizing agent. Or a solution containing an appropriate electrolyte is electrochemically polymerized to be adhered onto the dielectric layer to form a solid electrolyte layer.

The polypyrroles made of these have a high electric conductivity, and a solid electrolytic capacitor using the polypyrrole has very good high frequency characteristics.

In the case of using a sintered body of fine tantalum powder as the valve metal, a method of chemically polymerizing in order to fill the solid electrolyte into the pores of the electrode and increase the capacity achievement rate is available. It is common.

Specifically, after forming a tantalum electrode, it is immersed in a pyrrole monomer solution containing a pyrrole monomer and an additive, and then an oxidizing agent such as ferric sulfate, ferric chloride or hydrogen peroxide is used. Immersing in an oxidant solution containing a suitable dopant composition and additives to produce a conductive polymer of polypyrrole by chemical polymerization, washing with water, and drying, a series of from dipping to pyrrole monomer solution to drying This is a method in which the conductive polymer is attached to the surface of the oxide film dielectric layer by repeating the process several times.

In order to improve the characteristics of the leakage current and the withstand voltage of the solid electrolytic capacitor, repair formation is performed in a chemical conversion liquid during or after the polymerization, and the solid electrolytic capacitor which has been assembled is subjected to temperature and humidity. A method of providing a so-called aging step of applying a voltage for a certain time in a high state is known.

[0009]

However, if there are many defects in the oxide film dielectric layer before forming the solid electrolyte layer made of a conductive polymer, even if aging is performed after the capacitor element is completed, it is sufficient. However, there is a problem in that the yield cannot be repaired because defects that the leakage current is large and defects that are short-circuits occur without being repaired.

Further, when chemical conversion is carried out in a chemical conversion liquid in order to repair the defective portion of the oxide film dielectric layer between the chemical polymerization or after the chemical polymerization, a space between the solid electrolyte layer and the oxide film dielectric layer is formed. In this case, gas generation and discharge are likely to occur, peeling of the solid electrolyte layer and destruction of the oxide coating dielectric layer occur, resulting in an increase in the number of chemical polymerizations, deterioration of leakage current and withstand voltage characteristics, and a reduction in yield. There were challenges.

Furthermore, even when the assembled solid electrolytic capacitor is aged by applying a voltage 1.3 times the rated value for a certain period of time in a state where the temperature is as high as 85 ° C. and the relative humidity is as high as 85%. However, under these conditions, the formation reaction is difficult to proceed, and the defects in the deep portion of the capacitor element cannot be sufficiently repaired, so that there is a problem that it is difficult to greatly improve the characteristics of leakage current and withstand voltage.

The present invention solves the above-mentioned problems.
It is an object of the present invention to provide a method for manufacturing a solid electrolytic capacitor having a high process yield, a low leakage current, and a high withstand voltage.

[0013]

According to the present invention, a chemical conversion step is carried out before forming a solid electrolyte layer such as a conductive polymer at a low current density or by using a chemical conversion liquid having a low electric conductivity. A method of manufacturing a capacitor is represented by an aging step of applying different voltages, preferably 1.3 to 2 times the rated voltage, in an atmosphere having pressure or pressure.

With the above structure, the process yield is good,
Provided is a method for manufacturing a solid electrolytic capacitor having a low leakage current and a high withstand voltage.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention according to claim 1 provides a step of preparing a valve metal body which is a sintered body, and a first step for forming an oxide film dielectric layer on the valve metal body. A first chemical conversion step of performing a first chemical conversion by a current density, and a second current density lower than the first current density subsequent to the first chemical conversion step for the valve metal body after the first chemical conversion step It is a method of manufacturing a capacitor including a second chemical conversion step of performing chemical conversion and a step of disposing a cathode body so as to face the valve metal body.

With such a structure, an oxide film dielectric layer having few defects can be formed, and a solid electrolytic capacitor having excellent characteristics of leakage current and withstand voltage can be obtained.

Next, the present invention according to claim 2 provides a step of preparing a valve metal body which is a sintered body, and a first electric conductivity for forming an oxide film dielectric layer on the valve metal body. A first chemical conversion step of performing a first chemical conversion using a first chemical conversion liquid having, and the valve metal body after the first chemical conversion step is smaller than the first electrical conductivity following the first chemical conversion step. A method of manufacturing a capacitor comprising: a second chemical conversion step of performing a second chemical conversion using a second chemical conversion liquid having a second electrical conductivity; and a step of disposing a cathode body facing the valve metal body. is there.

With such a structure, an oxide film dielectric layer with few defects can be formed, and a solid electrolytic capacitor having excellent characteristics of leakage current and withstand voltage can be obtained.

Further, as in claim 3, there is an aging step of performing aging after the second chemical conversion step, and as in claim 4, after the second chemical conversion step and before the aging step, an oxide film dielectric is formed. It is preferable to perform a conductive polymer layer forming step of forming a conductive polymer layer adjacent to the body layer by polymerization.

By providing the aging process in this manner, moisture is absorbed to the deep part of the capacitor element, and the chemical conversion reaction is promoted, so that defects in the deep part of the capacitor element can be sufficiently repaired, and leakage current and withstand voltage are reduced. A solid electrolytic capacitor having excellent characteristics can be obtained.

Further, according to claim 5, the valve metal body after the second chemical conversion step is subjected to the third chemical conversion by a third current density lower than the first current density following the second chemical conversion step. Or a third lower chemical conductivity lower than the first electric conductivity following the second chemical conversion step with respect to the valve metal body after the second chemical conversion step. By having a third chemical conversion step of performing a third chemical conversion using a third chemical conversion liquid having the electric conductivity of, it is possible to form an oxide film dielectric layer with fewer defects and to improve the characteristics of leakage current and withstand voltage. An excellent solid electrolytic capacitor can be obtained.

Alternatively, as described in claim 7, a step of preparing a valve metal body that is an etched foil and a first current density for forming an oxide film dielectric layer on the valve metal body A second chemical conversion step of performing chemical conversion and a second chemical conversion step of the valve metal body after the first chemical conversion step, following the first chemical conversion step, with a second current density lower than the first current density. A chemical conversion step, a third chemical conversion step of performing a third chemical conversion with a third current density lower than the first current density following the second chemical conversion step for the valve metal body after the second chemical conversion step, and 9. A method of manufacturing a capacitor, comprising the step of disposing a cathode body facing a valve metal body.
As described above, a step of preparing a valve metal body that is an etched foil, and a first chemical conversion liquid having a first electrical conductivity to form an oxide film dielectric layer on the valve metal body. A first chemical conversion step of performing a first chemical conversion using, and a second electrical conductivity smaller than the first electrical conductivity of the valve metal body after the first chemical conversion step following the first chemical conversion step. A second chemical conversion step of performing a second chemical conversion using a second chemical conversion liquid,
Following the second chemical conversion step, the valve metal body after the second chemical conversion step is subjected to a third chemical conversion using a third chemical conversion liquid having a third electrical conductivity smaller than the first electrical conductivity. A method of manufacturing a capacitor may include a third formation step and a step of disposing a cathode body so as to face the valve metal body.

With such a structure, even if an etched foil is used instead of a sintered body, an oxide film dielectric layer with few defects can be formed, and a solid electrolytic capacitor having excellent characteristics of leakage current and withstand voltage can be obtained. .

Further, as described in claim 9,
After the third chemical conversion step, an aging step for performing aging is provided, and the conductive polymer layer is polymerized adjacent to the oxide film dielectric layer after the third chemical conversion step and before the aging step. It is preferable to perform the conductive polymer layer forming step to be formed.

By providing the aging process in this manner, moisture is absorbed to the deep part of the capacitor element, and the chemical conversion reaction is promoted, so that the defect in the deep part of the capacitor element can be sufficiently repaired, and the leakage current and the withstand voltage can be improved. A solid electrolytic capacitor having excellent characteristics can be obtained.

Further, as described in claim 11, the aging step according to claim 3, 4, 9 or 10 is performed in a pressurized atmosphere, and as described in claim 12, the aging steps are different from each other. A plurality of aging steps depending on the applied voltage may be included, and it is preferable that the applied voltage of the aging is 1.3 to 2 times the rated value as described in claim 13, and the effect of the aging is more remarkable. become.

Alternatively, as described in claim 14, a step of preparing a valve metal body which is a sintered body, a chemical conversion step of forming an oxide film dielectric layer on the valve metal body, and a post-chemical conversion step. A method of manufacturing a capacitor, comprising: an aging step of performing a plurality of agings with different applied voltages of 1.3 to 2 times the rated pressure while applying a pressure; and a step of disposing a cathode body facing the valve metal body. May be

By providing the characteristic aging process as described above, moisture is absorbed to the deep part of the capacitor element, and the chemical conversion reaction is promoted, so that the defect in the deep part of the capacitor element can be sufficiently repaired and the leakage current A solid electrolytic capacitor having excellent withstand voltage characteristics can be obtained.

In this case, as described in claim 15, the chemical conversion step includes a first chemical conversion step of performing a first chemical conversion with a first current density to form an oxide film dielectric layer on the valve metal body, 17. A second chemical conversion step of performing a second chemical conversion on the valve metal body after the first chemical conversion step, following the first chemical conversion step with a second current density lower than the first current density. As described above, the method may further include a third chemical conversion step of performing a third chemical conversion on the valve metal body after the second chemical conversion step with a third current density lower than the first current density.

Alternatively, in the chemical conversion process according to claim 17, the first chemical conversion liquid having a first electric conductivity is used to form an oxide film dielectric layer on the valve metal body. A first chemical conversion step of performing chemical conversion, and a second chemical conversion having a second electrical conductivity smaller than the first electrical conductivity subsequent to the first chemical conversion step with respect to the valve metal body after the first chemical conversion step. A second chemical conversion step of performing a second chemical conversion using a liquid, as described in claim 18, further to the first chemical conversion step for the valve metal body after the second chemical conversion step. The third chemical conversion step of performing the third chemical conversion using a third chemical conversion liquid having a third electric conductivity smaller than the electric conductivity of

These conversion steps further reduce defects in the oxide dielectric layer. As described in claim 19, after the chemical conversion step according to any one of claims 13 to 18, it is preferable to form a conductive polymer layer adjacent to the oxide film dielectric layer by polymerization.

As described in claim 20, the chemical conductivity of the chemical conversion liquid used in the chemical conversion steps other than the first chemical conversion step is preferably 1 mS / cm or less.

Further, as set forth in claim 21, further
The method may further include a manganese dioxide forming step of forming a manganese dioxide layer between the oxide-coated dielectric layer and the conductive polymer layer, and the cathode body may be formed on the oxide-coated dielectric layer side. It is preferable that it is composed of a carbon layer arranged in the above and a silver paint layer adjacent to the carbon layer.

Each embodiment of the present invention will be described below. (Embodiment 1) In this embodiment, first, the size is 2X.
A tantalum sintered body having a size of 1.4 × 0.9 mm and a weight of about 13.5 mg on which a tantalum lead wire was arranged was prepared.

The tantalum sintered body has fine pores facing from the surface to the inside or inside thereof.

Then, as the first chemical conversion, this tantalum sintered body was dipped in a solution of phosphoric acid (5 ml) dissolved in 1000 ml of deionized water at about 90 ° C., and a voltage of 0 to 33.9 V was applied at a rate of 5 mV / sec. After applying while raising to 3
A constant voltage of 3.9 V was applied for 60 minutes, and the current per element (tantalum sintered body) was about 80 μA (current density 5.9
mA / g) and an oxide film dielectric layer was formed by anodic oxidation. Then, it was washed with running deionized water.

Then, as the second chemical conversion, the deionized water is immersed in a solution having an electric conductivity of about 0.5 μS / cm (adjusted to be smaller than the electric conductivity in the case of the first chemical conversion), and 35 V is applied at about 25 ° C. Applying for 5 minutes, the current per element (sintered tantalum) is 0.6μA (current density 44.4μA / g)
Then, the defective portion of the oxide film dielectric layer was repaired by anodic oxidation.

Thereafter, as a third chemical conversion, 0.05 ml of acetic acid was immersed in a solution of 1000 ml of deionized water and having an electric conductivity of about 41 μS / cm, and the mixture was kept at about 25 ° C. for 3 hours.
0V is applied for 30 minutes, and the current per element (tantalum sintered body) is 0.07 μA (current density 5.2 μA / g)
After that, anodic oxidation was performed in two steps in addition to the second formation to repair the defective portion of the oxide film dielectric layer.

Then, it was washed with running deionized water and dried. When this structure was regarded as a capacitor and the capacity in the chemical conversion liquid was measured, it was 17 μF.

Further, using this composition, after being immersed for 2 minutes in a pyrrole monomer solution consisting of 6.7 g of a pyrrole monomer, 3 g of a surfactant sodium alkylnaphthalene sulfonate (average molecular weight 338), 100 g of deionized water and 2 g of ethanol, , Ferric sulfate hydrate (water content 26
%), 12 g of surfactant sodium alkylnaphthalene sulfonate (average molecular weight 338), 110 g of deionized water, 10 g of ethanol, and 1.4 g of para-nitrophenol were immersed in an oxidant solution for 10 minutes.

The treatment of immersing in the pyrrole monomer solution and the oxidizing agent solution was repeated three times, followed by washing with running deionized water for 10 minutes and drying in an oven at 105 ° C. for about 5 minutes.

Then, subsequently, a pyrrole monomer solution,
The process of dipping in an oxidizing agent solution and drying in an oven was repeated 6 times to form a conductive polymer solid electrolyte layer of polypyrrole doped with divalent sulfate ions and monovalent alkylnaphthalene sulfonate ions.

In the case of the present embodiment, the total number of repetitions of immersion in the pyrrole monomer solution and the oxidant solution required for forming the solid electrolyte layer is 18 times.

Then, a cathode was formed with a carbon layer and a silver paint layer on the solid electrolyte layer thus formed, and a cathode lead was attached thereon.

Further, in an atmosphere of a temperature of 85 ° C. and a relative humidity of 85%, the voltage is first changed from 0 to 1 at a speed of 5 mV / sec.
After the voltage was raised to 3V, a constant voltage of 13V was applied for 60 minutes for aging treatment. At this time, in order to prevent the current from flowing too much and being broken, each element has a resistance of 10 kΩ.
I placed a protection resistor.

Finally, drying at a temperature of 120 ° C. for 60 minutes,
A total of 10 capacitor elements were completed.

Then, for these 10 elements, 1
The capacity at 20 Hz, the loss factor, the impedance at 400 kHz, the leakage current after applying the rated voltage of 10 V for 2 minutes, and the withstand voltage were measured, and their average values are shown in the following (Table 1). In addition, the number of repetitions of chemical polymerization is also shown.

[0048]

[Table 1]

Comparative Example 1 Next, as Comparative Example 1, 10 capacitor elements were completed under the same conditions as in Embodiment 1 except that the second formation and the third formation were not performed.

120 Hz for these 10 elements
, The loss coefficient, the impedance at 400 kHz, the leakage current after applying the rated voltage of 10 V for 2 minutes, and the withstand voltage were measured, and their average values are shown in the above (Table 1).

The leakage current is not shown in the table because it varies widely from 0.5 μA to short circuit (large current).

Further, the withstand voltage is not shown in the table because there are many elements having a short circuit failure. Comparing the comparative example 1 in Table 1 with the first embodiment, in the comparative example 1, only the first chemical formation was performed without performing the second chemical conversion and the third chemical conversion. I can't stand it,
While the leakage current is large and defects such as short-circuiting are likely to occur, and the yield is poor, according to the first embodiment, a chemical conversion liquid having low electric conductivity is used before the formation of the electrolyte and at a low current density, It can be understood that the characteristics of leakage current and withstand voltage are improved by performing the second formation and the third formation.

Therefore, according to the first embodiment, the second and third chemical conversions are performed at a low current density using the chemical conversion liquid having a low electric conductivity before forming the solid electrolyte layer made of the conductive polymer. By doing so, an oxide film dielectric layer with few defects could be formed.

Further, after assembling the capacitor element, the defects of the oxide film dielectric layer can be better repaired by performing aging in which a voltage is applied for a certain period of time in an atmosphere of high temperature and high relative humidity. It was possible to obtain a solid electrolytic capacitor having excellent characteristics of leakage current and withstand voltage.

(Comparative Example 2) As Comparative Example 2, another example in which the second and third chemical conversions are not performed will be described.

First, with a size of 2 × 1.4 × 0.9 mm,
A tantalum sintered body having a tantalum lead wire and having a weight of about 13.5 mg is prepared.

Then, as the first chemical conversion, this tantalum sintered body was immersed in a solution of phosphoric acid (5 ml) dissolved in deionized water (1000 ml) at about 90 ° C., and the voltage was 0 to 33.9 V at a rate of 5 mV / sec. The voltage per unit device (tantalum sintered body) was 80 μA (current density 5.9).
mA / g) and an oxide film dielectric layer was formed by anodic oxidation.

Here, this structure is regarded as a capacitor,
When the capacity in the chemical conversion liquid was measured, it was 17.2 μF.

Then, it is washed with running deionized water,
After drying, the same pyrrole monomer solution and oxidant solution as in Embodiment 1 were used, and then immersed in the pyrrole monomer solution for 2 minutes and then in the oxidant solution for 10 minutes.

After this immersion treatment was repeated 3 times, washing was performed with running deionized water for 20 minutes, and 0.05 ml of acetic acid was added to 1 ml.
Using a solution dissolved in 000 ml of deionized water, about 25
At 20 ° C., 20 V was applied for 30 minutes to carry out anodic oxidation to perform a repair chemical treatment for repairing the defective portion of the oxide film dielectric layer.

Then, it was washed with running deionized water for 10 minutes and dried in an oven at 105 ° C. for 5 minutes.

After that, the above-mentioned treatments such as immersion in a pyrrole monomer solution and an oxidant solution, and washing are repeated 14 times, and 2
A solid electrolyte layer composed of a conductive polymer of polypyrrole doped with monovalent sulfate ions and monovalent alkylnaphthalene sulfonate ions was formed.

In this comparative example, the total number of times of dipping the pyrrole monomer solution and the oxidant solution required for forming the solid electrolyte layer was 42 times.

On the solid electrolyte layer thus formed, a cathode was formed with a carbon layer and a silver paint layer, and a cathode lead was attached thereon.

Then, in an atmosphere of a temperature of 85 ° C. and a relative humidity of 85%, an aging treatment was carried out by first increasing the voltage from 0 to 13 V at a rate of 5 mV / sec and then applying a constant voltage of 13 V for 60 minutes. At this time, a protective resistance of 10 kΩ was provided for each element in order to prevent the current from flowing and being broken.

Finally, drying at a temperature of 120 ° C. for 60 minutes,
A total of three capacitor elements were completed.

There are seven elements in which the formation current cannot be extremely narrowed down due to the peeling of the solid electrolyte layer and the destruction of the oxide film dielectric layer during the restoration formation in the formation liquid. Since it is known that the characteristics of leakage current and withstand voltage are poor even after the element is finished, it was excluded as a defect.

With respect to these three elements, the capacitance at 120 Hz, the loss factor, the impedance at 400 kHz, the leakage current after applying the rated voltage of 10 V for 2 minutes, and the withstand voltage were measured, and the average value thereof was calculated as described above (Table 1)
It was shown to. The number of repetitions of chemical polymerization is also shown in (Table 1).

Comparing the comparative example 2 with the first embodiment, in the comparative example 2, gas is generated between the solid electrolyte layer and the oxide film dielectric layer because the restoration chemical conversion is performed after the polymerization. And discharge is likely to occur, peeling of the solid electrolyte layer and destruction of the oxide film dielectric layer, resulting in an increase in the number of chemical polymerizations and deterioration of impedance, leakage current and withstand voltage characteristics, resulting in lower yield. On the other hand, in the first embodiment, such a situation does not occur, the characteristics of the leakage current and the withstand voltage are good, the yield can be increased, and the number of times of the chemical polymerization can be reduced, so that the manufacturing cost can be reduced. It can be understood that can be lowered.

In the first embodiment, it is preferable to perform both the second and third chemical conversions, but it is possible to repair the defects in the oxide film dielectric layer by performing only one of them. It is not necessary to do both.

Further, in the first embodiment, tantalum is not limited as long as it has fine holes.

(Second Embodiment) In the present embodiment, the first embodiment is different except that the steps after the aging treatment are changed.
A capacitor element was produced in the same manner as in.

First, with a size of 2 × 1.4 × 0.9 mm,
A tantalum sintered body having a tantalum lead wire and a weight of about 13.5 mg was prepared.

To carry out the first chemical conversion, this tantalum sintered body was immersed in a solution of phosphoric acid (5 ml) dissolved in deionized water (1000 ml) at a temperature of about 90 ° C., and then 5 mV / sec.
At a rate of 0 to 33.9V while increasing the voltage, then a constant voltage of 33.9V was applied for 60 minutes, and the current per device (tantalum sintered body) was about 80 μA (current density 5.9 mA). / G) and the oxide film dielectric layer was formed by anodic oxidation.

Then, after washing with running deionized water, the second chemical conversion was carried out with an electric conductivity of deionized water of about 0.5 μS.
/ Cm (adjusted to be smaller than the electrical conductivity of Daiichi Kasei)
Immersed in the solution of No.3 and applied 35V at 25 ° C for 5 minutes, and the current per element (tantalum sintered body) is 0.6 μA.
The current density was reduced to 44.4 μA / g and the process was performed.

Next, as the third chemical conversion, 0.05 ml of acetic acid
Electric conductivity of about 4 dissolved in 1000 ml of deionized water
Using a solution of 1 μS / cm, 30 V was applied for 30 minutes at about 25 ° C., and the current per element (tantalum sintered body) was reduced to 0.07 μA (current density 5.2 μA / g),
The defect portion of the oxide film dielectric layer by anodic oxidation was repaired.

Then, it was washed with running deionized water and dried. When this structure was regarded as a capacitor and the capacity in the chemical conversion liquid was measured, it was 17 μF.

Using this construction, 6.7 g of a pyrrole monomer and 3 g of a surfactant sodium alkylnaphthalene sulfonate (average molecular weight 338) were immersed in a pyrrole monomer solution consisting of 3 g, deionized water 100 g and ethanol 2 g for 2 minutes. , Ferric sulfate hydrate (water content 26
%) 12 g, the surfactant 12 g, and deionized water 110
g, ethanol 10 g, and para-nitrophenol 1.4 g
Was immersed in the oxidant solution consisting of 10 minutes.

The treatment of immersing in the pyrrole monomer solution and the oxidizing agent solution was repeated three times, followed by washing with running deionized water for 10 minutes, and then in an oven at 105 ° C. for 5 minutes.
Allow to dry for minutes.

Then, the treatment after the dipping in the pyrrole monomer solution and the oxidant solution was repeated 6 times, and the divalent sulfate ion and the monovalent alkylnaphthalene sulfonate ion were doped (polypyrrole) conductive polymer. To form a solid electrolyte layer.

In the present embodiment, the total number of repetitions of immersion in the pyrrole monomer solution and the oxidant solution required for forming the solid electrolyte layer is 18 times.

Then, a cathode was formed with a carbon layer and a silver paint layer on the tantalum sintered body on which the polypyrrole was formed in this way, and a cathode lead was attached thereon.

Thereafter, the temperature is 122 ° C., the relative humidity is 95%,
In a pressurized atmosphere of 1 kg / cm ² (atmospheric pressure +
At 1 kg / cm ² ), voltage was applied at a rate of 5 mV / sec while increasing from 0 to 13 V, and then a constant voltage of 13 V was applied for 60 minutes for aging treatment. At this time, a protective resistance of 10 kΩ was provided for each element in order to prevent the current from flowing and being broken.

Finally, it was dried at a temperature of 120 ° C. for 60 minutes to complete a total of 10 capacitor elements.

For these 10 elements, 120 Hz
, The loss coefficient, the impedance at 400 kHz, the leakage current after applying the rated voltage of 10 V for 2 minutes, and the withstand voltage were measured, and their average values are shown in the above (Table 1). The number of times of repeating the chemical polymerization is also shown.

In this embodiment, the aging treatment conditions in the first embodiment are changed, but the voltage is applied for a certain period of time in an atmosphere in which the temperature and relative humidity are appropriately high and pressure is applied. By performing the aging treatment, the moisture is absorbed to the deep part of the capacitor element, and the chemical conversion reaction is promoted at a high temperature, so that the defects of the oxide film dielectric layer in the deep part of the capacitor element can be sufficiently repaired. It was found that a capacitor with low leakage current and high withstand voltage can be obtained.

Furthermore, the result that the variation of the leakage current and the withstand voltage is small and the yield is good is obtained.

Aging conditions other than those described in the present embodiment, for example, 115 ° C., 80%, (atmospheric pressure + 0.
3 kg / cm ² ), 115 ° C., 95%, (atmospheric pressure +0.
6 kg / cm ² ), 122 ° C., 80%, (atmospheric pressure +0.
7 kg / cm ² ), 135 ° C, 95%, (atmospheric pressure +
It was found that almost the same effect was obtained even in an atmosphere of 1.9 kg / cm ² ) and a sufficiently good result was obtained in a wide range of conditions.

Further, in the present embodiment, it is preferable to perform both the second and third chemical conversions, but it is possible to repair the defects in the oxide film dielectric layer by performing only one of them. It is not necessary to do both.

Further, in the present embodiment, tantalum is not limited as long as it has fine holes.

(Embodiment 3) This embodiment is the same as Embodiment 2 except that the following third formations (A) to (F) are executed instead of the third formation. It is the same.

Specifically, 9.4 g of (A) phenol was dissolved in 1000 ml of deionized water to obtain an electric conductivity of about 1.
30V at about 25 ° C using a chemical solution of 7μS / cm
The current per element was reduced to 0.4 μA (current density 29.6 μA / g), and (B) ammonium adipate 30 mg was dissolved in 1000 ml of deionized water to obtain an electric conductivity of about 34 μS / cm conversion liquid, 30V was applied for 30 minutes at about 25 ° C., the current per element was reduced to 0.09 μA (current density 6.7 μA / g), (C) Oxalic acid 9 mg was 1000 ml. Using a chemical conversion solution having an electric conductivity of about 35 μS / cm dissolved in deionized water of 30 V, 30 V was applied for 30 minutes at about 25 ° C., and the current per device was 0.09 μA (current density was 6.7 μA).
/ G), (D) 10 ml of acetic acid to 1000
Electric conductivity of about 640 μS / ml dissolved in deionized water
cm chemical solution, 30 V was applied for 30 minutes at about 25 ° C., and the current per device was reduced to 0.06 μA (current density 4.4 μA / g), (E) citric acid 21
Using a chemical solution having an electric conductivity of about 2.8 mS / cm dissolved in 1000 ml of deionized water, 30 V was applied for 30 minutes at about 25 ° C., and the current per element was 0.32 μA.
(Current density 23.7 μA / g), and (F) 9 g of oxalic acid dissolved in 1000 ml of deionized water were used to form a chemical conversion liquid having an electric conductivity of about 18.6 mS / cm.
30 V was applied for 30 minutes at about 25 ° C., and the current per device was reduced to 0.07 μA (current density 5.2 μA / g).

In the present embodiment, each of the above third chemical conversions,
Ten capacitor elements were completed in the same manner as in Embodiment 2 except that the number of repetitions of polymerization was different.

With respect to these elements, the capacitance at 120 Hz, the loss coefficient, the impedance at 400 kHz, the leakage current after applying the rated voltage of 10 V for 2 minutes, and the withstand voltage were measured, and the average value thereof was described above (Table 1). The number of repetitions of chemical polymerization is also shown.

From the results obtained by using the above-mentioned chemical conversion liquids, it can be seen that the leakage current of the completed capacitor element tends to be smaller when the third chemical conversion is performed by using the chemical conversion liquid having a low electric conductivity. I understand.

It is considered that the leakage current becomes smaller when the third chemical conversion liquid having a lower electric conductivity is used, because the oxide film dielectric layer having less defects is obtained, and the electric conductivity of the chemical conversion liquid is reduced. Is considered to be preferably 1 mS / cm or less.

Although the direct correlation between the narrowed current density value and the leakage current of the completed capacitor element was not obtained exactly, judging from the fact that the leakage current characteristics were good, several μA / It is thought that it is necessary to limit it to about g to several tens of μA / g.

Although the present embodiment has been described based on the second embodiment, the same applies to the first embodiment.

(Embodiment 4) In the present embodiment, the formation by deionized water in Embodiment 2 is not carried out, but the formation is performed by using an acetic acid aqueous solution as the second formation, and the third formation is carried out. It was designed so that it would not exist.

As the second chemical conversion in the present embodiment,
A solution of 0.001 ml of acetic acid dissolved in 1000 ml of deionized water and having an electric conductivity of about 6 μS / cm (adjusted to be smaller than the electric conductivity of Daiichi Kasei) was used at about 25 ° C. for 30 minutes.
V is applied for 60 minutes and the current per element is 0.09
The oxide film dielectric layer was formed by the first chemical conversion and the second chemical conversion while narrowing down to μA (current density of 6.7 μA / g).

The number of repetitions of polymerization was 21 times,
Other than the above, ten capacitor elements were completed in the same manner as in the second embodiment.

For these 10 elements, 120 Hz
, The loss coefficient, the impedance at 400 kHz, the leakage current after applying the rated voltage of 10 V for 2 minutes, and the withstand voltage were measured, and their average values are shown in the above (Table 1).

In the present embodiment, after the first chemical conversion, the chemical conversion is not performed with deionized water, but only the aqueous acetic acid solution is subjected to chemical conversion. However, almost the same characteristics as those of the second embodiment are obtained. The yield was also good.

Also in this embodiment, it is considered that the electric conductivity of the chemical conversion liquid in the second chemical conversion is preferably 1 mS / cm or less.

The current density is also several μA / g to several tens of μA.
It is considered that it is preferable to limit to / g.

Further, although the present embodiment has been described based on the second embodiment, the same applies to the first embodiment.

(Embodiment 5) In the present embodiment, the applied voltage under the aging treatment conditions in Embodiment 2 is 13V.
Ten capacitor elements were completed in the same manner as in Embodiment 2 except that the voltage was changed from (1.3 times the rating) to 19 V (1.9 times the rating).

For these 10 elements, 120 Hz
, The loss coefficient, the impedance at 400 kHz, the leakage current after applying a rated voltage of 10 V for 2 minutes, and the withstand voltage, and the average value thereof is shown in (Table 1) above, and the number of times of chemical polymerization is also repeated. The results are shown in (Table 1).

According to the present embodiment, the chemical conversion reaction is promoted by increasing the applied voltage of aging, and the defects of the oxide film dielectric layer can be sufficiently repaired, so that the characteristics of the leakage current and the withstand voltage are significantly increased. Improved, low leakage current,
It was found that a capacitor having a high withstand voltage can be obtained.

Further, variations in leakage current and withstand voltage were small, and good yields were obtained.

(Embodiment 6) In this embodiment, the second and third chemical conversions were not carried out, and the aging treatment was carried out under pressure to fabricate a capacitor element.

First, with a size of 2 × 1.4 × 0.9 mm,
A tantalum sintered body having a tantalum lead wire and a weight of about 13.5 mg was prepared.

The tantalum sintered body has fine pores facing from the surface to the inside or inside thereof.

Then, this tantalum sintered body was treated with phosphoric acid 5
Immerse 100 ml of the solution in 1000 ml of deionized water at a temperature of about 90 ° C., and then at 0 to 33.
While increasing the voltage to 9 V, a voltage was applied, and then a constant voltage of 33.9 V was applied for 60 minutes to form an oxide film dielectric layer by anodic oxidation to perform the first chemical conversion.

Then, it was washed with running deionized water and dried. Here, when this configuration was regarded as a capacitor and the capacity in the chemical conversion liquid was measured, it was 17.3 μF.
Met.

Further, using this constitution, after 6.7 g of a pyrrole monomer and 3 g of a surfactant sodium alkylnaphthalene sulfonate (average molecular weight 338), 100 g of deionized water and 2 g of ethanol were immersed in a pyrrole monomer solution for 2 minutes. , Ferric sulfate hydrate (water content 26
%) 12 g, the surfactant 12 g, and deionized water 110
g, ethanol 10 g, and para-nitrophenol 1.4 g
Was immersed in the oxidant solution consisting of 10 minutes.

Then, the treatment of immersing in the pyrrole monomer solution and the oxidizing agent solution was repeated three times, washed with running deionized water for 10 minutes, and dried in an oven at 105 ° C. for 5 minutes.

Further, subsequently, a pyrrole monomer solution,
The treatment after the immersion in the oxidizing agent solution was repeated 6 times to form a solid electrolyte layer made of a conductive polymer of polypyrrole doped with divalent sulfate ions and monovalent alkylnaphthalene sulfonate ions.

The number of times of immersion in the pyrrole monomer solution and the oxidizing agent solution required for forming the solid electrolyte layer was repeated 18 times in total.

Then, on the tantalum sintered body on which the polypyrrole was formed in this way, a cathode was formed with a carbon layer and a silver paint layer, and a cathode lead was attached thereon.

Thereafter, the temperature is 122 ° C., the relative humidity is 95%,
In a pressurized atmosphere of 1 kg / cm ² (atmospheric pressure +
1 kg / cm ² ), first increase the voltage from 0 to 10 V at a speed of 5 mV / sec, apply a constant voltage of 10 V for 60 minutes, and then increase the voltage from 10 to 14 V at a speed of 5 mV / sec, then a constant voltage of 14 V. Is applied for 30 minutes and then 5 mV
17V after increasing from 14 to 17V at the speed of / sec
A constant voltage was applied for 30 minutes to perform aging treatment. At this time, a protective resistance of 10 kΩ was provided for each element in order to prevent the current from flowing and being broken.

Finally, drying was performed at a temperature of 120 ° C. for 60 minutes to complete a total of 10 capacitor elements.

For these 10 elements, 120 Hz
, The loss coefficient, the impedance at 400 kHz, the leakage current after applying a rated voltage of 10 V for 2 minutes, and the withstand voltage, and the average value thereof is shown in (Table 1) above, and the number of times of chemical polymerization is also repeated. It is shown together.

In this embodiment, the capacitor element is subjected to an aging process in which the applied voltage is raised stepwise from a low voltage to a high voltage in an atmosphere in which temperature and relative humidity are appropriately high and pressure is applied. Moisture is absorbed up to the deep part of the capacitor, the temperature is high, and the applied voltage is high, which promotes the chemical conversion reaction, and the defects in the oxide film dielectric layer in the deep part of the capacitor element can be sufficiently repaired. It was possible to obtain a capacitor element having excellent withstand voltage characteristics.

Further, it was found that the generation of short defects due to aging can be reduced by gradually increasing the applied voltage and gradually repairing the defects.

In this embodiment, tantalum is not limited as long as it has fine holes.

(Embodiment 7) In the present embodiment, there is prepared a tantalum sintered body having a size of 2 × 1.4 × 0.9 mm and a weight of about 13.5 mg on which tantalum lead wires are arranged.

The tantalum sintered body has fine pores facing from the surface to the inside or inside thereof.

Then, this tantalum sintered body was treated with phosphoric acid 5
Immerse 100 ml of the solution in 1000 ml of deionized water at a temperature of about 90 ° C., and then at 0 to 33.
The voltage was applied while raising it to 9 V, and then the constant voltage of 33.9 V was applied for 60 minutes, and the current per element (tantalum sintered body) was about 80 μA (current density as high as 5.9 mA / g). After squeezing, an oxide film dielectric layer was formed by anodic oxidation.

After that, it was washed with running deionized water,
After drying, manganese nitrate hexahydrate and deionized water were mixed at a ratio of 1:10 for 1 minute and then left to stand for 5 minutes to dry, then at a temperature of 300 ° C and a relative humidity of 85%. A manganese dioxide layer was formed on the oxide-coated dielectric layer by pyrolyzing for 20 minutes in an atmosphere.

Next, the electric conductivity of deionized water is about 0.5 μm.
It was adjusted to be smaller than the electrical conductivity of S / cm Daiichi Kasei. )
35V was applied for 30 minutes at about 25 ° C., and the current per element (tantalum sintered body) was 0.9 μA.
The second chemical conversion was carried out by narrowing down to (current density 66.7 μA / g).

Then, as the third chemical conversion, acetic acid of 0.
Using a solution of 05 ml dissolved in 1000 ml of deionized water and having an electric conductivity of about 41 μS / cm, 30 V at about 25 ° C.
Is applied for 30 minutes and the current per device is 0.08μ.
After narrowing to A (current density 5.9 μA / g), the defective portion of the oxide film dielectric layer was repaired by anodic oxidation.

Then, it was washed with running deionized water and dried. Here, this configuration was regarded as a capacitor, and the capacity in the chemical conversion solution was measured to be 18 μF.

Further, using this constitution, after 6.7 g of a pyrrole monomer and 3 g of a surfactant sodium alkylnaphthalene sulfonate (average molecular weight of 338), 100 g of deionized water and 2 g of ethanol were immersed in a pyrrole monomer solution for 2 minutes. , Ferric sulfate hydrate (water content 26
%) 12 g, the surfactant 12 g, and deionized water 110
g, ethanol 10 g, and para-nitrophenol 1.4 g
Was immersed in the oxidant solution consisting of 10 minutes.

Then, the treatment of immersing in the pyrrole monomer solution and the oxidizing agent solution was repeated three times, followed by washing with running deionized water for 10 minutes and drying in an oven at 105 ° C. for 5 minutes.

Thereafter, the treatment after immersion in the pyrrole monomer solution and the oxidant solution is repeated 8 times, and the conductive polymer of polypyrrole doped with divalent sulfate ion and monovalent alkylnaphthalene sulfonate ion is formed. A solid electrolyte layer was formed.

The number of times of immersion in the pyrrole monomer solution and the oxidizing agent solution required for forming the solid electrolyte layer in the present embodiment was repeated 24 times in total.

Then, on the solid electrolyte layer thus formed, a cathode was formed with a carbon layer and a silver paint layer, and a cathode lead was attached thereon.

Thereafter, the temperature is 122 ° C., the relative humidity is 95%,
In a pressurized atmosphere of 1 kg / cm ² (atmospheric pressure +
At 1 kg / cm ² ), first, the voltage was raised from 0 to 19 V at a speed of 5 mV / sec, and then an aging treatment was performed by applying a constant voltage of 19 V for 60 minutes. At this time, in order to prevent the current from flowing and being destroyed, 10
A protective resistance of kΩ is arranged.

Finally, drying at a temperature of 120 ° C. for 60 minutes,
A total of 10 capacitor elements were completed.

For these 10 elements, 120 Hz
, The loss coefficient, the impedance at 400 kHz, the leakage current after applying the rated voltage of 10 V for 2 minutes, and the withstand voltage were measured, and their average values are shown in the above (Table 1).

In the present embodiment, the manganese dioxide layer is provided between the oxide film dielectric layer and the solid electrolyte layer made of a conductive polymer, but good characteristics similar to those of the fifth embodiment can be obtained. The yield was also good.

If a manganese dioxide layer is provided between the oxide film dielectric layer and the solid electrolyte layer made of a conductive polymer, the characteristics are improved in the atmosphere of 25 ° C., 50 ° C., 75 ° C., 100 ° C. and 125 ° C. When measured, as shown in (Table 2) below, it was found that the characteristics of the loss coefficient at 120 Hz at high temperature were less likely to change and a capacitor having excellent temperature characteristics was obtained, as compared with the fifth embodiment.

[0144]

[Table 2]

In the present embodiment, it is preferable to perform both the second and third chemical conversions, but it is possible to repair the defects in the oxide film dielectric layer by performing only one of them. It is not necessary to do both.

Further, although the present embodiment has been described based on the fifth embodiment, the same applies to the other embodiments.

Further, in the present embodiment, tantalum is not limited as long as it has fine holes.

(Embodiment 8) In this embodiment, instead of the tantalum sintered body, an aluminum etched foil having a length of 7 mm and a width of 10 mm provided with anode leads was prepared.

Fine irregularities are formed on the surface of the aluminum etched foil by etching.

Then, the aluminum etched foil was applied to 7
Immerse in a 3% ammonium adipate aqueous solution at 0 ° C., first apply a voltage at a rate of 10 mV / sec while increasing it from 0 to 65 V, and then apply a constant voltage of 65 V for 40 minutes to obtain an element (aluminum etched foil) 1 The oxide film dielectric layer was formed on the surface of the etched foil by anodic oxidation by narrowing the current per piece to about 45 μA (current density as high as 32 μA / cm ² ).

Then, wash with running deionized water,
After drying, soak in 1% manganese nitrate 30% aqueous solution for 1 minute and let stand for 5 minutes to dry.
A thermal decomposition treatment was carried out by heating at 0 ° C. for 30 minutes to form a conductive layer of manganese dioxide on the oxide film dielectric layer.

Then, it was immersed in a solution of 3% ammonium adipate aqueous solution having an electric conductivity of about 22 mS / cm (adjusted to be smaller than the electric conductivity of Daiichi Kasei) at 6 ° C. at about 70 ° C.
Applying 3V for 20 minutes, the current per element (aluminum etched foil) is 40μA (current density 28.6μ
The second chemical conversion was carried out by squeezing it to A / cm ² ).

Next, as the third chemical conversion, the electrical conductivity of a 0.003% ammonium adipate aqueous solution was about 34 μS / c.
m, the solution of 63V is applied at about 25 ° C. for 20 minutes,
The current per element is 0.08 μA (current density 0.0
It was carried out by squeezing to 6 μA / cm ² ) and the defective portion of the oxide film dielectric layer was repaired by anodization.

Then, the etched foil provided with the conductive layer of manganese dioxide was treated with hydroxybenzoic acid (0.15
M), pyrrole (0.5 M), sodium triisopropylnaphthalenesulfonate (0.1 M) and deionized water, and the polymerization initiation electrode is placed close to the conductive layer. A constant voltage of 2.5 V was applied for 30 minutes to carry out an electrolytic polymerization reaction to form a solid electrolyte layer composed of a conductive polymer of polypyrrole.

After the solid electrolyte layer was formed, it was washed with water and dried, and then a cathode was formed on the solid electrolyte layer with a carbon layer and a silver paint layer, and a cathode lead was attached thereon.

Thereafter, the temperature is 122 ° C., the relative humidity is 95%,
In a pressurized atmosphere of 1 kg / cm ² (atmospheric pressure +
At 1 kg / cm ² ), first, the voltage was increased from 0 to 26 V at a speed of 5 mV / sec, and then an aging treatment was performed by applying a constant voltage of 26 V for 60 minutes. At this time, in order to prevent the current from flowing and being destroyed, 10
A protective resistance of kΩ is arranged.

Finally, drying at a temperature of 120 ° C. for 60 minutes,
A total of 10 capacitor elements were completed.

For these 10 elements, 120 Hz
, The loss coefficient, the impedance at 400 kHz, the leakage current after applying the rated voltage of 16 V for 2 minutes, and the withstand voltage were measured, and their average values are shown in the above (Table 1).

In this embodiment, by forming the third chemical conversion at a low current density using a chemical conversion liquid having a low electric conductivity before forming the solid electrolyte layer made of a conductive polymer, oxidation with few defects is performed. By forming a coated dielectric layer and performing an aging process of applying a high voltage for a certain period of time in an atmosphere where the temperature is high, the relative humidity is high and the pressure is applied after the capacitor element is assembled, Water is absorbed deep into the element, the temperature is high,
Since the applied voltage is high, the chemical conversion reaction is accelerated, and even the defects in the oxide film dielectric layer in the deep part of the capacitor element can be sufficiently repaired, so a capacitor element with excellent characteristics of leakage current and withstand voltage can be obtained. I was able to.

Further, variations in leakage current and withstand voltage were small, and good yields were obtained.

(Comparative Example 3) As Comparative Example 3, the third chemical conversion is not performed, and the aging condition is that the temperature is 85 ° C and the relative humidity is 85%.
Voltage is applied while increasing from 1 to 20.8V, and then 2
Ten capacitor elements were completed under the same conditions as in Embodiment 8, except that a constant voltage of 0.8 V (voltage 1.3 times the rated voltage) was applied for 60 minutes.

For these 10 elements, 120 Hz
, The loss coefficient, the impedance at 400 kHz, the leakage current after applying the rated voltage of 16 V for 2 minutes, and the withstand voltage were measured, and their average values are shown in the above (Table 1).

Comparative Example 3 and Embodiment 8 in Table 1
As is clear from the comparison with the above, it was found that the capacitor according to the eighth embodiment has excellent characteristics in leakage current and withstand voltage.

When the requirements for leakage current and withstand voltage are not so high and the level of Comparative Example 3 is sufficient, Embodiment 8 will be described.
In, the third chemical conversion may be omitted, or, in some cases, the second chemical conversion may be omitted and the third chemical conversion may be performed.

In the eighth embodiment, the manganese dioxide conductive layer is provided, but it can be omitted.

In the eighth embodiment, the aluminum etched foil is not limited as long as it has fine irregularities. (Embodiment 9) Also in this embodiment, an aluminum etched foil having a length of 7 mm and a width of 10 mm with an anode lead is prepared.

Fine irregularities are formed on the surface of this aluminum etched foil by etching.

Then, the aluminum etched foil was applied to 7
Immerse in 3% ammonium adipate aqueous solution at 0 ° C., first apply a voltage at a rate of 10 mV / sec while increasing from 0 to 65 V, and then apply a constant voltage of 65 V for 40 minutes to anodic-oxidize the surface of the etched foil. First formation was performed to form an oxide-coated dielectric layer on.

Then, washing with running deionized water,
After drying, soak in 1% manganese nitrate 30% aqueous solution for 1 minute and let stand for 5 minutes to dry.
A thermal decomposition treatment was carried out by heating at 0 ° C. for 30 minutes to form a conductive layer of manganese dioxide on the oxide film dielectric layer.

Thereafter, using a 3% ammonium adipate aqueous solution, 63 V was applied for 20 minutes at about 70 ° C., and a second chemical conversion for repairing the defective portion of the oxide film dielectric layer by anodic oxidation was performed. The electric conductivity and the current density of this second chemical conversion were adjusted to be smaller than those of the first chemical conversion.

Next, an etched foil provided with a conductive layer of manganese dioxide was prepared from hydroxybenzoic acid (0.15M), pyrrole (0.5M), sodium triisopropylnaphthalenesulfonate (0.1M) and deionized water. In the electrolytic polymerization solution, the polymerization initiating electrode is brought close to the conductive layer, and a constant voltage of 2.5 V is applied to the polymerization initiating electrode for 30 minutes to carry out the electropolymerization reaction to obtain a polypyrrole conductive polymer. To form a solid electrolyte layer.

After the solid electrolyte layer was formed, it was washed with water and dried, and then a cathode was formed on the solid electrolyte layer with a carbon layer and a silver paint layer, and a cathode lead was attached thereon.

Thereafter, the temperature is 122 ° C., the relative humidity is 95%,
In a pressurized atmosphere of 1 kg / cm ² (atmospheric pressure +
1 kg / cm ² ), first increase the voltage from 0 to 16 V at a speed of 5 mV / sec and then apply a constant voltage of 16 V for 60 minutes, then increase the voltage from 16 to 20 V at a speed of 5 mV / sec and then a constant voltage of 20 V. Is applied for 30 minutes and then 5 mV
24V after increasing from 20 to 24V at the speed of / sec
A constant voltage was applied for 30 minutes to perform aging treatment. At this time, a protective resistance of 10 kΩ was provided for each element in order to prevent the current from flowing and being broken.

Finally, drying at a temperature of 120 ° C. for 60 minutes,
A total of 10 capacitor elements were completed.

For these 10 elements, 120 Hz
, The loss coefficient, the impedance at 400 kHz, the leakage current after applying the rated voltage of 16 V for 2 minutes, and the withstand voltage were measured, and their average values are shown in the above (Table 1).

In this embodiment, the capacitor element is subjected to an aging process in which the applied voltage is increased stepwise from a low voltage to a high voltage in an atmosphere in which the temperature and relative humidity are appropriately high and pressure is applied. Moisture is absorbed up to the deep part of the capacitor, the temperature is high, and the applied voltage is high, which promotes the chemical conversion reaction, and the defects in the oxide film dielectric layer in the deep part of the capacitor element can be sufficiently repaired. It was possible to obtain a capacitor element having excellent withstand voltage characteristics.

Furthermore, it was found that short-circuit defects due to aging can be reduced by gradually increasing the applied voltage and gradually repairing the defects.

In the present embodiment, the structure in which the manganese dioxide conductive layer is provided has been described, but it can be omitted.

In the present embodiment, the aluminum etched foil is not limited as long as it has fine irregularities.

In each of the above embodiments, an example in which the solid electrolyte layer made of a conductive polymer is made of polypyrrole has been described, but other polythiophenes and polyanilines can be similarly made.

Further, in each of the above embodiments, it is preferable that the applied voltage is 1.3 to 2 times the rated value for the aging, and the aging can be similarly performed even after the capacitor element is molded with resin. is there.

Further, it is preferable that the chemical conductivity of the chemical conversion liquid used for the second chemical conversion and / or the third chemical conversion in each of the above embodiments is 1 mS / cm or less.

[0183]

As described above, in the present invention, an oxide film dielectric having few defects can be obtained by using a chemical conversion liquid having a low electric conductivity before forming the solid electrolyte layer or by performing a chemical conversion at a low current density. A layer can be formed, and a solid electrolytic capacitor having excellent characteristics of leakage current and withstand voltage can be obtained.

Furthermore, there is no need to perform repair chemical conversion in the chemical conversion liquid between polymerizations or after polymerization, and the process is simplified.

Furthermore, since the solid electrolyte layer is not peeled off due to the repair formation, the number of times of repeating the polymerization is small, so that the cost can be reduced, and the dielectric layer of the oxide film is not destroyed by the repair formation. Therefore, the characteristics of leakage current and withstand voltage do not deteriorate, so that the yield can be increased.

By performing an aging treatment in which a voltage is applied for a certain period of time in an atmosphere in which the temperature is high, the relative humidity is high, and the pressure is applied, even a defect in the oxide film dielectric layer in the deep portion of the capacitor element is detected. Since it can be repaired, it is possible to obtain a capacitor having a low leakage current and a high withstand voltage, and further, a variation in the leakage current and the withstand voltage is reduced, and a good yield can be obtained.

Further, by increasing the applied voltage of this aging to a voltage higher than 1.3 times the rated voltage, it is possible to obtain a capacitor having greatly improved characteristics of leakage current and withstand voltage.

Further, when the manganese dioxide layer is provided between the oxide film dielectric layer and the solid electrolyte layer made of a conductive polymer, the characteristics of the loss coefficient at high temperatures are unlikely to change, and the solid electrolytic capacitor having excellent temperature characteristics. Can be obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuo Kudo 3-10-1 Higashisanda, Tama-ku, Kawasaki City, Kanagawa Prefecture Matsushita Giken Co., Ltd.

Claims (22)

[Claims] 1. A step of preparing a valve metal body which is a sintered body, and a first chemical conversion step of performing a first chemical conversion at a first current density to form an oxide film dielectric layer on the valve metal body. A second chemical conversion step of performing a second chemical conversion on the valve metal body after the first chemical conversion step with a second current density lower than the first current density following the first chemical conversion step, and the valve metal. And a step of disposing the cathode body so as to face the body. 2. A step of preparing a valve metal body which is a sintered body, and a first chemical conversion liquid having a first electric conductivity for forming an oxide film dielectric layer on the valve metal body. A first chemical conversion step of performing a first chemical conversion step, and a second electrical conductivity smaller than the first electrical conductivity of the valve metal body after the first chemical conversion step following the first chemical conversion step. A method of manufacturing a capacitor, comprising: a second chemical conversion step of performing a second chemical conversion using the second chemical conversion solution; and a step of disposing a cathode body facing the valve metal body. 3. The method for producing a capacitor according to claim 1, further comprising an aging step of performing aging after the second chemical conversion step. 4. The method according to claim 3, further comprising a conductive polymer layer forming step of polymerizing a conductive polymer layer adjacent to the oxide film dielectric layer after the second chemical conversion step and before the aging step. Manufacturing method of capacitors. 5. A third chemical conversion step of performing the third chemical conversion on the valve metal body after the second chemical conversion step, following the second chemical conversion step, with a third current density lower than the first current density. The method of manufacturing a capacitor according to claim 1, further comprising: 6. A third chemical conversion liquid having a third electrical conductivity lower than the first electrical conductivity is further added to the valve metal body after the second chemical conversion process, following the second chemical conversion process. The method for manufacturing a capacitor according to claim 2, further comprising a third chemical conversion step of performing a third chemical conversion using the third chemical conversion step. 7. A step of preparing a valve metal body, which is an etched foil, and a first chemical conversion step of performing a first chemical formation with a first current density to form an oxide film dielectric layer on the valve metal body. A second chemical conversion step of performing a second chemical conversion on the valve metal body after the first chemical conversion step by a second current density lower than the first current density following the first chemical conversion step, and the second chemical conversion A third chemical conversion step of performing a third chemical conversion by a third current density lower than the first current density subsequent to the second chemical conversion step on the valve metal body after the step, and a cathode facing the valve metal body. A method of manufacturing a capacitor having a step of arranging a body. 8. A step of preparing a valve metal body, which is an etched foil, and a first chemical conversion liquid having a first electrical conductivity for forming an oxide film dielectric layer on the valve metal body. A first chemical conversion step of performing a first chemical conversion using, and a second electrical conductivity smaller than the first electrical conductivity of the valve metal body after the first chemical conversion step following the first chemical conversion step. A second chemical conversion step of performing a second chemical conversion using a second chemical conversion liquid,
Following the second chemical conversion step, the valve metal body after the second chemical conversion step is subjected to a third chemical conversion using a third chemical conversion liquid having a third electrical conductivity smaller than the first electrical conductivity. A method of manufacturing a capacitor, comprising: a third chemical conversion step; and a step of disposing a cathode body facing the valve metal body. 9. The method of manufacturing a capacitor according to claim 5, further comprising an aging step of performing aging after the third chemical conversion step. 10. The method according to claim 9, further comprising a conductive polymer layer forming step of polymerizing a conductive polymer layer adjacent to the oxide film dielectric layer after the third chemical conversion step and before the aging step. Manufacturing method of capacitors. 11. The method for manufacturing a capacitor according to claim 3, 4, 9, or 10, wherein the aging step is performed in a pressurized atmosphere. 12. The aging process includes a plurality of aging processes with different applied voltages.
Alternatively, the method for manufacturing the capacitor according to any one of 9 to 11. 13. The applied voltage of aging is rated at 1.3.
The method for manufacturing a capacitor according to claim 3, 4 or 9 to 12, which is doubled. 14. A step of preparing a valve metal body which is a sintered body, a chemical conversion step of forming an oxide film dielectric layer on the valve metal body, and a step of applying a rating of 1. while applying pressure after the chemical conversion step.
A method of manufacturing a capacitor, comprising: an aging step of performing a plurality of agings with applied voltages of 3 to 2 times different from each other; and a step of disposing a cathode body facing the valve metal body. 15. The chemical conversion step comprises a first chemical conversion step of performing a first chemical conversion at a first current density to form an oxide coating dielectric layer on the valve metal body, and the valve metal after the first chemical conversion step. 15. The method of manufacturing a capacitor according to claim 14, further comprising a second chemical conversion step of performing a second chemical conversion on the body with the second current density lower than the first current density following the first chemical conversion step. 16. The capacitor according to claim 15, further comprising a third chemical conversion step in which the valve metal body after the second chemical conversion step is subjected to a third chemical conversion with a third current density lower than the first current density. Production method. 17. The first chemical conversion step of performing the first chemical conversion using a first chemical conversion liquid having a first electrical conductivity to form an oxide film dielectric layer on the valve metal body. A second chemical conversion using a second chemical conversion liquid having a second electric conductivity smaller than the first electric conductivity subsequent to the first chemical conversion step with respect to the valve metal body after the first chemical conversion step. The method of manufacturing a capacitor according to claim 14, further comprising a second chemical conversion step. 18. A third chemical conversion liquid having a third electrical conductivity smaller than the first electrical conductivity is further added to the valve metal body after the second chemical conversion step, following the second chemical conversion step. 3. A third chemical conversion step of performing a third chemical conversion using the method.
7. The method for manufacturing a capacitor according to 7. 19. The production of a capacitor according to claim 13, further comprising a conductive polymer layer forming step of forming a conductive polymer layer adjacent to the oxide film dielectric layer by polymerization after the chemical conversion step. Method. 20. The method for producing a capacitor according to claim 1, wherein the chemical conductivity of the chemical conversion liquid used in the chemical conversion steps other than the first chemical conversion step is 1 mS / cm or less. 21. The method of manufacturing a capacitor according to claim 1, further comprising a manganese dioxide forming step of forming a manganese dioxide layer between the oxide film dielectric layer and the conductive polymer layer. 22. The method of manufacturing a capacitor according to claim 1, wherein the cathode body is composed of a carbon layer arranged on the oxide film dielectric layer side and a silver paint layer adjacent to the carbon layer.