JP2007012650A - Method of manufacturing solid electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a solid electrolytic capacitor that reduces a leakage current, and prevents deterioration in ESR characteristics. <P>SOLUTION: In the method of the solid electrolytic capacitor: a dielectric oxide film, and a conductive polymer that becomes a solid electrolyte are formed on the surface of a sintered compact made of tantalum or niobium powder; heat treatment is applied to a capacitor element in which carbon and silver layers are formed successively; and then a voltage is applied for performing element aging treatment. A temperature of the heat treatment is 100-180°C and a time of the heat treatment is 10-30 minutes. A temperature of the element aging treatment is 40-100°C. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  Conventionally, a solid electrolytic capacitor in which a valve action metal powder such as tantalum or niobium is molded and sintered to form an anode body and a conductive polymer typified by polypyrrole or polythiophene is used as a solid electrolyte is used for forming a solid electrolyte or a cathode. At the time of forming the extraction layer, heat treatment and curing treatment are repeated.

  In order to reduce the leakage current of the solid electrolytic capacitor that increases by repeating this heat treatment and curing treatment, element aging treatment is applied to the capacitor element before resin encapsulation at a temperature higher than the maximum operating temperature, and again after resin encapsulation. A method of aging processing is disclosed (for example, see Patent Document 1).

  Also disclosed is an aging treatment method in which a predetermined voltage is applied to a solid electrolytic capacitor after resin encapsulation, the temperature is rapidly increased from room temperature to high temperature, and then a thermal shock is applied to cool to room temperature (for example, Patent Document 2). reference).

Furthermore, a method is disclosed in which after a conductive polymer is formed in a capacitor element, heat treatment is performed at a temperature of less than 200 ° C. before aging (see, for example, Patent Document 3).
Japanese Patent No. 3515327 JP 2004-128032 A JP 2003-17369 A

However, the capacitor element before encapsulating the resin is subjected to aging treatment in which a voltage is applied at a temperature higher than the maximum operating temperature, and the aging treatment is performed again after encapsulating the resin. The problem that the conductive polymer is insulated by the Joule heat generated by the aging current at a high temperature is larger than the effect of repairing. When a high CV valve action metal powder with a larger surface area is used for the capacitor element, there are many bonding parts between primary particles with low mechanical strength, and there are many parts with low withstand voltage, so a large aging current is required, There is a problem in that the area of the polymer to be insulated increases, resulting in deterioration of ESR characteristics.
In addition, the aging treatment method in which a predetermined voltage is applied to the solid electrolytic capacitor after resin encapsulation, the temperature is rapidly increased from room temperature to a high temperature, and then the thermal shock is cooled to room temperature, the voltage is also applied during the thermal shock. Therefore, in the solid electrolytic capacitor element using the high CV valve action metal powder which is easily oxidized, there is a problem that the product yield is lowered due to excessive screening due to oxidation by aging and heating.
Furthermore, after the conductive polymer is formed in the capacitor element, the heat treatment is performed at a temperature of less than 200 ° C. before aging. Since the anode element was oxidized during aging and the number of defects in the oxide film increased during aging, there was a problem of increasing leakage current.

  Because of the above problems, a method for producing a conductive polymer solid electrolytic capacitor using a high CV valve action metal powder has been demanded.

  The present invention solves the above problems, and after a dielectric oxide film is formed on the surface of a sintered body made of valve action metal powder, the capacitor element on which a solid electrolyte, a carbon layer, and a silver layer are formed is subjected to heat treatment. Then, a method for producing a solid electrolytic capacitor is characterized in that a voltage is applied to perform element aging treatment.

  Moreover, the temperature of said heat processing is 100-180 degreeC, It is a manufacturing method of the solid electrolytic capacitor characterized by the above-mentioned.

  Furthermore, the time for the above heat treatment is 10 to 30 minutes.

  Moreover, the temperature of said element aging process is 40-100 degreeC, It is a manufacturing method of the solid electrolytic capacitor characterized by the above-mentioned.

  In the present invention, a capacitor element in which a dielectric oxide film is formed on the surface of a sintered body made of a valve action metal powder and then a solid electrolyte, followed by a carbon layer and a silver layer is heat-treated at a high temperature of 100 to 180 ° C. After that, in order to perform element aging in an atmosphere of 100 ° C. or less, there is no increase in the defect portion of the oxide film due to element aging in a high temperature exceeding 100 ° C., and there is no deterioration of ESR characteristics due to deterioration of the conductive polymer, In addition, a solid electrolytic capacitor having excellent leakage current characteristics can be provided.

[Example 1]
Below, the manufacturing method of the solid electrolytic capacitor by this invention is demonstrated. First, 100,000 CV / g valve action metal powder is pressure-molded and sintered to a size of 0.7 mm × 0.9 mm × 0.6 mm to obtain a sintered body element. The sintered body element is anodized in an acidic aqueous solution to form a dielectric oxide film. Thereafter, a solid electrolyte made of a conductive polymer such as polypyrrole, polythiophene, or polyaniline is formed on the dielectric oxide film, and then a carbon layer and a silver layer are formed to form a capacitor element.

  Next, as a heat treatment, the capacitor element was left in a constant temperature bath at 100 ° C. for 30 minutes, and then a voltage of 7 V was applied in an atmosphere at 40 ° C. to perform an element aging treatment for 30 minutes. After the aging treatment, a lead metal frame was connected to the anode lead and the cathode silver layer, respectively, and a 4V-33 μF rated solid electrolytic capacitor was produced through a resin exterior, 4 V, 120 minutes aging process, final inspection, and the like. .

[Example 2]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the temperature of the heat treatment was 150 ° C.

[Example 3]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the temperature of the heat treatment was 180 ° C.

[Example 4]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the temperature of the heat treatment was 150 ° C. and the element aging treatment was performed at 60 ° C.

[Example 5]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the temperature of the heat treatment was 150 ° C. and the element aging treatment was carried out at 80 ° C.

[Example 6]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the temperature of the heat treatment was 150 ° C. and the element aging treatment was performed at 100 ° C.

[Example 7]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the heat treatment was performed at 150 ° C. for 10 minutes.

[Example 8]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the heat treatment was performed at 150 ° C. for 20 minutes.

[Comparative Example 1]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that no heat treatment was performed on the capacitor element.

[Comparative Example 2]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the temperature of the heat treatment was 80 ° C.

[Comparative Example 3]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the temperature of the heat treatment was 200 ° C.

[Comparative Example 4]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the temperature of the heat treatment was 150 ° C. and the temperature of the element aging treatment was 20 ° C.

[Comparative Example 5]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the temperature of the heat treatment was 150 ° C. and the temperature of the element aging treatment was 120 ° C.

[Comparative Example 6]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the heat treatment was performed at 150 ° C. for 5 minutes.

[Comparative Example 7]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the heat treatment was performed at 150 ° C. for 40 minutes.

(Conventional example)
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that the capacitor element was not subjected to heat treatment and was subjected to element aging treatment at a high temperature of 125 ° C.
Table 1 shows measurement results of electrical characteristics in Examples 1 to 3, conventional examples, and Comparative Examples 1 to 3.
Table 2 shows measurement results of electrical characteristics in Examples 4 to 6 and Comparative Examples 4 and 5.
Further, Table 3 shows the measurement results of electrical characteristics in Examples 7 and 8 and Comparative Examples 6 and 7.

  As apparent from Table 1, Examples 1 to 3 have improved leakage current as compared with Comparative Example 1 and the conventional example. In addition, when the heating temperature is 80 ° C. (Comparative Example 2), the leakage current is not sufficiently reduced, and when the heating temperature is 200 ° C. (Comparative Example 3), the ESR deteriorates, so the range of the heating temperature is 100 to 180 ° C. desirable.

  As is apparent from Table 2, Examples 4 to 6 show approximately the same low leakage current. However, when the element aging treatment temperature is 20 ° C. (Comparative Example 4) and 120 ° C. (Comparative Example 5), the leakage current increases, and thus the element aging treatment temperature is desirably 40 to 100 ° C.

  As is apparent from Table 3, Examples 7 and 8 show almost the same low leakage current. However, when the heating time is 5 minutes (Comparative Example 6), the leakage current is high, and when the heating time is 40 minutes (Comparative Example 7), the number of steps is required.

  In the present invention, a conductive polymer is used as the solid electrolyte, but the same effect can be obtained even when manganese dioxide is used.

It is the schematic which shows the element aging processing method of a capacitor | condenser element.

Explanation of symbols

1 Anode lead 2 Capacitor element 3 Cathode film 4 Aging power source

Claims (4)

  After forming a dielectric oxide film on the surface of the sintered body made of valve metal powder, heat treatment is performed on the capacitor element on which the solid electrolyte, carbon layer, and silver layer are formed, and then voltage is applied to the element aging process. A method for producing a solid electrolytic capacitor, comprising:   The temperature of the heat processing of Claim 1 is 100-180 degreeC, The manufacturing method of the solid electrolytic capacitor characterized by the above-mentioned.   The method of manufacturing a solid electrolytic capacitor, wherein the heat treatment time according to claim 1 is 10 to 30 minutes.   The method for producing a solid electrolytic capacitor, wherein the temperature of the element aging treatment according to claim 1 is 40 to 100 ° C.

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