JPH10289839A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a small-sized and large-capacity solid electrolytic capacitor by a method wherein a conductive function high-molecular film layer is formed on an anodized film layer on the surface of a valve action metal film in an electrolyte, which is an aqueous solution containing a pyrol, a borosisalicylic acid ammonium, a boric acid and a citric acid, and a conductor layer is formed on the high-molecular film layer. SOLUTION: An anodized film layer 1 is formed on the surface of an aluminium foil 3 formed with a valve action metal film with the roughened surface and a conductive function high-molecular film layer 4 is formed on the layer 1 in an electrolyte, which is an aqueous solution containing a pyrol, a borosisalicylic acid ammonium, a boric acid and a citric acid, by an electrolytic oxidation polymerization method. After that, a conductor layer 7 is formed on the layer 4, the part, which is not formed with the layer 4, of the foil 3 is cut in a prescribed length and a capacitor element 8 of a solid electrolytic capacitor is manufactured using this part as an anode terminal part and using the part, which is not formed with the layer 7, of the foil 3 as a cathode terminal part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a solid electrolytic capacitor using a conductive functional polymer film layer as an electrolyte.

[0002]

2. Description of the Related Art With the recent miniaturization, high performance, high temperature and high reliability of electronic equipment, the power supply unit used in this electronic equipment has been rapidly becoming smaller and longer lasting. In order to reduce the size and extend the life of the power supply, the following performance is required especially for the output smoothing capacitor used in the output smoothing circuit section. (1) Low impedance, low equivalent series resistance (ESR)
Have a value.

(2) Capacitor characteristic values are stable at high temperatures.

(3) Small size and large capacity.

[0005] In response to the above requirements, a low impedance, low equivalent series resistance (ES) using manganese dioxide, TCNQ salt, and a conductive functional polymer film as a solid electrolyte has been conventionally used.
Solid electrolytic capacitors having R) values have been developed.
The characteristics of these capacitors are determined by the electric conductivity of the solid electrolyte used, and solid capacitors using a conductive functional polymer membrane as an electrolyte are particularly excellent as compared with other capacitors.

A method for forming a conductive polymer film on the anodic oxide film layer formed on the surface of the valve metal is as follows.
A method of forming by an electrolytic oxidation polymerization method in a solution containing an electrolyte and pyrrole, and a method in which an oxidizing agent is previously deposited on an anodic oxide film and then formed by a chemical polymerization method in a liquid containing the electrolyte and pyrrole. There is a way.

[0007]

In the method using a chemical polymerization method to form the conductive polymer film, ferric chloride is generally used as an oxidizing agent, but aluminum foil is used as a valve metal. Ferric chloride has the disadvantage of dissolving the aluminum foil.

[0008] Further, the method using the electrolytic oxidation polymerization method is as follows:
In a non-aqueous electrolyte such as acetonitrile and acetone, the applied voltage (= V _f ) when forming the anodic oxide film is:
The applied voltage (= V ₀ ) during the electrolytic oxidation polymerization is V ₀ = (1.5
3.0) is required × V _f position. Therefore, there is a disadvantage that the current flowing through the anodic oxide film layer during the electrolytic oxidation polymerization locally crystallizes the anodic oxide film layer at a location where the current has passed, resulting in a large leakage current value. This tendency is due to the applied voltage (=
Since _Vf ) increases as the value increases, there is also a disadvantage that it becomes difficult to manufacture a high withstand voltage capacitor. There is also a disadvantage that the cost is higher than that of the aqueous electrolyte solution.

When a conductive functional polymer film is formed by electrolytic oxidation polymerization in an aqueous electrolyte solution, it can be easily formed on a metal plate on which no anodic oxide film is formed. On the layer, it was impossible to form a conductive functional polymer film with a generally used electrolyte composition. This tendency is due to the applied voltage (=
Higher V _f ) was more pronounced.

The present invention has been made in view of the above points, and eliminates the drawbacks of the above-mentioned conventional method, and has a high conductive function on an anodized film layer by an electrolytic oxidation polymerization method in a low-cost aqueous electrolyte solution. An object of the present invention is to provide a method for manufacturing a solid electrolytic capacitor capable of forming a molecular film.

[0011]

According to a first aspect of the present invention, an anodic oxide layer is formed on the surface of a valve metal, and pyrrole and borodisalicylic acid are formed on the anodic oxide layer. Forming a conductive functional polymer film layer by electrolytic oxidation polymerization in an electrolytic solution of an aqueous solution containing ammonium, boric acid and citric acid, and forming a conductor on the conductive functional polymer film layer to form a solid electrolytic capacitor Is manufactured.

The invention described in claim 2 is the first invention.
In the method for producing a solid electrolytic capacitor described in 1 above, the electrolytic solution contains 1 to 8% by weight of pyrrole, 0.1 to 0.5% by weight of ammonium borodisalicylate, and 0.1% by weight of boric acid.
It is an aqueous solution containing 0.1 to 2.0% by weight of citric acid.

According to a third aspect of the present invention, an anodic oxide film layer is formed on the surface of a valve metal, and pyrrole, ammonium borodisalicylate, boric acid, citric acid and dodecylbenzene are formed on the anodic oxide film layer. Forming a conductive functional polymer film layer by an electrolytic oxidation polymerization method in an electrolytic solution of an aqueous solution containing sodium sulfonate; and forming a conductor on the conductive functional polymer film layer to produce a solid electrolytic capacitor. It is characterized by.

The invention described in claim 4 is the third invention.
In the method for producing a solid electrolytic capacitor described in 1 above, the electrolytic solution contains 1 to 8% by weight of pyrrole, 0.1 to 0.5% by weight of ammonium borodisalicylate, and 0.1% by weight of boric acid.
-1.0% by weight, citric acid 0.1-2.0% by weight, sodium dodecylbenzenesulfonate 0.1-0.5%
It is characterized in that it is an aqueous solution containing% by weight.

The invention described in claim 5 is the first invention.
5. The method for manufacturing a solid electrolytic capacitor according to any one of items 1 to 4,
After a treatment in an aqueous solution of 10% by weight of ammonium borodisalicylate, a conductive functional polymer film layer is formed by electrolytic oxidation polymerization in an electrolytic solution of the aqueous solution.

The invention described in claim 6 is the first invention.
6. The method for manufacturing a solid electrolytic capacitor according to any one of Items 5 to 5, wherein the conductor formed on the conductive functional polymer film layer comprises a graphite layer and a silver paste layer.

The invention described in claim 7 is the first invention.
6. The method for manufacturing a solid electrolytic capacitor according to any one of Items 5 to 5, wherein the conductor formed on the conductive functional polymer film layer is formed by a solderable metal plating layer.

[0018]

Embodiments of the present invention will be described below. 2 to 4 are views showing steps of a method for manufacturing a solid electrolytic capacitor. As shown in FIG. 2, an anodic oxide film layer 1 is formed on the surface of an aluminum foil (aluminum-etched foil) 3 whose surface is roughened, heat-treated, and then insulated in a band shape around a predetermined position of the aluminum foil 3. A resist layer 2 is formed of a conductive resin.

FIG. 3 is a diagram showing a schematic configuration of an electrolytic oxidation polymerization apparatus for forming a conductive functional polymer film layer 4 on a portion of the aluminum foil 3 constituting a capacitor. The counter electrode 6 is disposed in the aqueous electrolyte solution 5 contained in the container 14, and the aluminum foil 3 is disposed opposite the counter electrode 6. By applying a predetermined current from the DC stabilizing power supply 15 using the aluminum foil 3 as an anode and the counter electrode 6 as a cathode, the portion of the anodic oxide film layer 1 immersed in the electrolytic solution 5 of the aqueous solution of the aluminum foil 3 is formed. The conductive functional polymer film layer 4 is formed.

After the conductive functional polymer film layer 4 is formed by the electrolytic oxidation polymerization method as described above, as shown in FIG.
Forming a conductor layer 7 on the conductive functional polymer film layer 4;
A portion of the aluminum foil 3 where the conductive functional polymer film layer 4 is not formed is cut to a predetermined length, and this portion is cut into the anode terminal portion 9 and the portion where the conductor layer 7 is formed is cut into the cathode terminal portion 10.
As a result, a capacitor element 8 of a solid electrolytic capacitor is formed.

The conductor layer 7 is composed of a graphite layer and a silver paste layer, or is composed of a plating layer of a solderable metal, for example, copper, tin, solder, nickel, brass, bronze or the like.

FIG. 5 is a diagram showing an example of a configuration in which a plurality of capacitor elements 8 having the above configuration are stacked to form a chip-type solid electrolytic capacitor. As shown in the figure, the anode terminals 9 and 9 of the capacitor elements 8 and 8 are respectively joined to both surfaces of the external anode electrode terminal portion 11 of the lead frame, and the capacitor elements 8 and 8 are respectively attached to both surfaces of the external cathode electrode terminal portion 12.
After joining the cathode terminal portions 10 and 10 and covering the entire surfaces of the capacitor elements 8 and 8 with the insulating resin mold 13,
The external anode electrode terminal portion 11 and the external cathode electrode terminal portion 12 are bent and formed on the lower surface of the insulating resin mold 13 to obtain a chip-type solid electrolytic capacitor.

The above-mentioned anode terminal 9 and external anode electrode terminal 1
1 is made by electric welding or laser welding, and the cathode terminal 10 and the external cathode electrode terminal 12 are joined by silver paste when the upper surface layer of the conductor layer 7 is silver paste. In the case of a possible metal plating layer, soldering is performed.

FIG. 1 is a diagram showing the composition of an aqueous electrolyte solution used in the method for manufacturing a solid electrolytic capacitor of the present invention and the composition of a comparative example. As shown in the figure, Comparative Example (1) uses an electrolytic solution having a composition of pyrrole = 5% by weight (wt.%), Dodecylbenzenesulfonic acid = 3% by weight, and pure water = 92% by weight. Uses an electrolytic solution having a composition of pyrrole = 5 wt.%, P-toluenesulfonic acid = 10 wt.%, And pure water 85 wt.%. In the course of the present invention, pyrrole = 5 wt.%, Ammonium borodisalicylate = 0.
An electrolytic solution having a composition of 5 wt% and pure water = 94.5 wt% is used.

In the present invention (A), pyrrole = 5 wt.%, Ammonium borodisalicylate = 0.3 wt.%, Boric acid = 0.6 wt.%, Citric acid = 0.4 wt.%, Sodium dodecylbenzenesulfonate = An electrolytic solution having a composition of 0.3 wt.% And pure water = 93.4 wt.% Is used. In the present invention (B), pyrrole = 5 wt.%, Ammonium borodisalicylate = 0.3 wt.%, Boric acid = 0.6
wt.%, citric acid = 0.4 wt.%, pure water = 93.7
An electrolytic solution having a composition of wt.% is used.

Embodiment 1 The area of the aluminum foil 3 shown in FIG. 2 where the conductive functional polymer film layer 4 is formed is 3 mm × 4 mm, the rated voltage is 16 V, and the rated capacity is 4.7.
In order to fabricate a solid electrolytic capacitor of μF, electrolytic oxidation polymerization was performed using an aqueous electrolyte solution shown in FIG. 1 and an apparatus shown in FIG. As a result, the aluminum foil 3
Only the electrolytic solution of the aqueous solution having the composition of the present invention (A) or (B) was able to form the conductive functional polymer film layer 4 on the anodic oxide film layer 1.

The conductive functional polymer can be formed by using the electrolytic solution in the course of the present invention. However, the capacitance of the manufactured solid electrolytic capacitor is limited by the electrolytic solutions (A) and (B) of the present invention. Since this is 10% to 30% of the solid electrolytic capacitor manufactured using the electrolytic solution, the electrolytic solution is not used in this embodiment.

An electroconductive functional polymer film layer 4 is formed on the anodic oxide film layer 1 of the aluminum foil 3 using an electrolytic solution of an aqueous solution having the composition of the present invention (A) or (B). A capacitor element 8 having the body layer 7 was manufactured, and a chip-type solid electrolytic capacitor having the configuration shown in FIG. 5 was manufactured using the capacitor element 8. The results of measuring the capacitor characteristics are shown in FIG.

As shown in FIG. 6, when the conductive functional polymer film layer 4 is formed with the electrolyte of the aqueous solution having the composition of the present invention (A) (Embodiment 1), the capacitance is 4.1 μF ( Frequency 1
20 Hz), Tan δ = 1.47% (frequency 120H)
z), equivalent series resistance value = 55.2 mΩ (frequency 100K
Hz), and a solid electrolytic capacitor having a capacitor characteristic having a leakage current value of 0.25 μA was obtained.

In the case where the conductive functional polymer film layer 4 is formed with the electrolytic solution of the aqueous solution having the composition of the present invention (B) (Embodiment 2), when the capacitance is 3.5 μF (frequency 120 Hz),
A solid electrolytic capacitor having capacitor characteristics of Tan δ = 2.25% (frequency 120 Hz), equivalent series resistance value = 75.6 mΩ (frequency 100 KHz), and leakage current value = 0.55 μA was obtained.

Embodiment 2 The area of the aluminum foil 3 shown in FIG. 2 where the conductive functional polymer film layer 4 is formed is 3 mm × 4 mm, the rated voltage is 16 V, and the rated capacity is 4.7.
In order to manufacture a solid electrolytic capacitor of μF, after forming an anodic oxide film layer 1 on an aluminum foil 3 and performing heat treatment, 5 wt% in the range of 0.1 to 10.0 wt.
-Immerse in an aqueous solution in which ammonium borodisalicylate is dissolved as a percentage for 10 to 12 minutes. In this case, the temperature of the aqueous solution is optimally 40 to 80 ° C. Thereafter, in the same manner as in the first embodiment, the conductive functional polymer film layer 4 and the conductor layer 7 are formed to produce a capacitor element 8, and a chip-type solid electrolytic capacitor is formed using the capacitor element 8. Made. The result of measuring the capacitor characteristics is shown in FIG.

As shown in FIG. 6, when the conductive functional polymer film layer 4 is formed with the electrolyte of the aqueous solution having the composition of the present invention (A) (Embodiment 2), the capacitance is 5.8 μF ( Frequency 1
20Hz), Tan δ = 0.92% (frequency 120H
z), Equivalent series resistance = 12.8 mΩ (frequency 100K
Hz), and a chip-type solid electrolytic capacitor having a capacitor characteristic of leakage current value = 0.15 μA was obtained.

When the conductive functional polymer film layer 4 was formed with the aqueous electrolyte solution of the composition of the present invention (B) (Embodiment 2), the capacitance was 4.7 μF (frequency 120 Hz),
A chip-type solid electrolytic capacitor having capacitor characteristics of an δ = 0.96% (frequency 120 Hz), equivalent series resistance = 15.7 mΩ (frequency 100 KHz), and leakage current = 0.65 μA was obtained.

As is clear from FIG. 6, when the conductive functional polymer film layer 4 was formed with the aqueous electrolyte solution of the composition of the present invention (A) or (B), the frequency was 10% lower than that of the first embodiment.
The equivalent series resistance value (ESR value) at 0 KHz is small, indicating that the effect of treating the anodic oxide film layer 1 with an aqueous solution in which ammonium borodisalicylate is dissolved is large.

The present invention (A) and (B) shown in FIG.
The composition of the electrolytic solution of the aqueous solution of is an example, and the composition is not limited thereto. In the electrolytic solution of the present invention (A), 1 to 8 wt.% Of pyrrole and 0.1% of ammonium borodisalicylate are used. ~ 0.5wt.%, Boric acid 0.1 ~
1.0 wt.%, Citric acid 0.1-2.0 wt.%,
Sodium dodecylbenzenesulfonate 0.1-0.5
The above characteristics are not lost in the range of wt.%.

Further, in the electrolytic solution of the present invention (A),
Pyrrole 1-8 wt.%, Ammonium borodisalicylate 0.1-0.5 wt.%, Boric acid 0.1-1.
The above characteristics are not lost in the range of 0 wt.% And citric acid in the range of 0.1 to 2.0 wt.%.

In the above embodiment, aluminum is used as an example of the valve metal used for the solid electrolytic capacitor. However, the valve metal is not limited to aluminum but may be a valve metal such as tantalum, titanium, or niobium. Is natural.

[0038]

As described above, according to the present invention as described above, the conductive functional polymer film layer can be formed on the anodic oxide film layer by electrolytic oxidation polymerization in an aqueous electrolyte. Compared to the conventional example formed by electrolytic oxidation polymerization in a non-aqueous electrolyte, low impedance, low equivalent series resistance,
Capacitor characteristics are stable at high temperature, and a small and large-capacity solid electrolytic capacitor can be manufactured at low cost.

According to the fifth aspect of the present invention, after the anodic oxide film layer is treated in a 0.1 to 10 wt.% Aqueous solution of ammonium borodisalicylate, the electrolytic oxidation polymerization method is carried out in an aqueous solution of the aqueous solution. Thus, a solid electrolytic capacitor having a small equivalent series resistance can be manufactured.

[Brief description of the drawings]

FIG. 1 is a diagram showing the composition of an electrolytic solution of an aqueous solution used in the method for manufacturing a solid electrolytic capacitor of the present invention and the composition of an electrolytic solution of an aqueous solution of a comparative example.

FIG. 2 is a view showing the structure of an aluminum foil used in the method for manufacturing a solid electrolytic capacitor of the present invention.

FIG. 3 is a diagram showing a schematic configuration of an electrolytic oxidation polymerization apparatus used in the method for producing a solid electrolytic capacitor of the present invention.

FIG. 4 is a view showing a configuration of a solid electrolytic capacitor element manufactured by the method for manufacturing a solid electrolytic capacitor of the present invention.

FIG. 5 is a diagram showing an example in which a solid electrolytic capacitor element manufactured by the method for manufacturing a solid electrolytic capacitor of the present invention is configured as a chip-type solid electrolytic capacitor.

FIG. 6 is a diagram showing capacitor characteristics of a solid electrolytic capacitor manufactured by the method for manufacturing a solid electrolytic capacitor of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anodized film layer 2 Resist layer of insulating resin 3 Aluminum foil 4 Conductive functional polymer film layer 5 Electrolyte of aqueous solution 6 Counter electrode 7 Conductive layer 8 Capacitor element 9 Anode terminal part 10 Cathode terminal part 11 External anode electrode Terminal part 12 External cathode electrode terminal part 13 Insulating resin mold 14 Container 15 DC stabilized power supply

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08K 5/55 C08K 5/55 C08L 65/00 C08L 65/00

Claims (7)

[Claims] An anodic oxide film layer is formed on a surface of a valve metal, and an electrolytic oxidative polymerization method is carried out on the anodic oxide film layer in an electrolytic solution of an aqueous solution containing pyrrole, ammonium borodisalicylate, boric acid and citric acid. A method for producing a solid electrolytic capacitor, comprising: forming a conductive functional polymer film layer by the method described above; and forming a conductor on the conductive functional polymer film layer. 2. The electrolyte according to claim 1, wherein the electrolytic solution contains 1 to 8% by weight of pyrrole, 0.1 to 0.5% by weight of ammonium borodisalicylate, 0.1 to 1.0% by weight of boric acid, and 0.1 to 1.0% by weight of citric acid. 1
2. The method for producing a solid electrolytic capacitor according to claim 1, wherein the aqueous solution contains an aqueous solution containing about 2.0% by weight. 3. An electrolytic solution of an aqueous solution comprising an anodic oxide film layer formed on the surface of a valve metal and comprising pyrrole, ammonium borodisalicylate, boric acid, citric acid and sodium dodecylbenzenesulfonate on the anodic oxide film layer. A method for producing a solid electrolytic capacitor, comprising: forming a conductive functional polymer film layer by an electrolytic oxidation polymerization method therein; and forming a conductor on the conductive functional polymer film layer. 4. The electrolytic solution according to claim 1, wherein the electrolytic solution contains 1 to 8% by weight of pyrrole, 0.1 to 0.5% by weight of ammonium borodisalicylate, 0.1 to 1.0% by weight of boric acid, and 0 to 10% by weight of citric acid. .
The method for producing a solid electrolytic capacitor according to claim 3, wherein the aqueous solution contains 1 to 2.0% by weight and 0.1 to 0.5% by weight of sodium dodecylbenzenesulfonate. 5. The method according to claim 1, wherein the anodic oxide film layer of the valve action metal has a thickness of 0.1 mm.
The conductive functional polymer film layer is formed by an electrolytic oxidation polymerization method in an electrolytic solution of the aqueous solution after treating in a 1 to 10% by weight aqueous solution of ammonium borodisalicylate. A method for manufacturing a solid electrolytic capacitor according to any one of the preceding claims. 6. The solid electrolyte according to claim 1, wherein the conductor formed on the conductive functional polymer film layer comprises a graphite layer and a silver paste layer. Manufacturing method of capacitor. 7. The method according to claim 1, wherein the conductor formed on the conductive functional polymer film layer is formed by a solderable metal plating layer. Manufacturing method of solid electrolytic capacitor.