JP2007035997A - Manufacturing method of solid electrolytic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor wherein its leakage current is improved, and its leakage current characteristic relative to its high-temperature loading test is improved. <P>SOLUTION: The manufacturing method of the solid electrolytic capacitor has a process for so molding pressingly a valve-action metal powder as to sinter it, a process for forming an oxidation film on the sintered body, a process for so laminating successively a solid electrolyte layer and a cathode deriving layer on the oxidation film as to obtain a capacitor element, and a process for forming an armored resin on the capacitor element. In this manufacturing method, when forming the armored resin, an injecting hole is formed as ranging from the armored surface to the capacitor element and an acidic solution is so injected into the injecting hole as to be subjected to an aging processing, and as to seal thereafter the injecting hole. Hereupon, the conductivity of the acidic solution is 10 μS/cm to 10 mS/cm, and the voltage of the aging processing is 0.3 to 4.0 times as high as the rated voltage of the solid electrolytic capacitor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a solid electrolytic capacitor, and more particularly to an aging treatment method.

Conventionally, a solid electrolytic capacitor is formed by sintering a molded body made of a valve metal powder having an anode lead planted, and then sequentially forming an oxide film, a solid electrolyte layer, a cathode lead layer made up of a carbon layer and a silver layer. As an element, the anode lead and the anode lead frame are connected, and the cathode lead layer and the cathode lead frame are connected via a conductive adhesive, and then covered with an exterior resin. However, when the exterior resin is cured, the resin contracts and mechanical stress is applied to the capacitor element, damaging the oxide film and increasing the leakage current of the solid electrolytic capacitor. For this reason, after forming an exterior resin on the capacitor element, an aging treatment is performed by applying a voltage at a high temperature. (For example, see Patent Document 1)
JP 2000-340466 A

  However, the conventional aging method is to apply voltage after forming the exterior resin and repair the oxide film to improve the leakage current characteristics. However, if the oxide film is not sufficiently repaired, the leakage current increases. There was a problem.

  The present invention solves the above-described problems, and provides a method for manufacturing a solid electrolytic capacitor with improved leakage current characteristics after aging and high reliability.

In the present invention, a valve action metal powder is pressure-formed, an oxide film is formed on a sintered sintered body, and an exterior resin is formed on a capacitor element in which a solid electrolyte layer and a cathode lead layer are sequentially formed on the oxide film. In the manufacturing method of the solid electrolytic capacitor formed,
A solid electrolytic capacitor characterized by forming an injection hole from the exterior surface to the capacitor element when forming the exterior resin, injecting an acidic solution into the injection hole, performing an aging treatment, and then sealing the injection hole It is a manufacturing method.

  Further, the present invention is a method for producing a solid electrolytic capacitor, wherein the electric conductivity of the acidic solution is 10 μS / cm to 10 mS / cm.

  Furthermore, the voltage for the above aging treatment is 0.3 to 4.0 times the rated voltage.

  Examples of the acidic solution include acetic acid, nitric acid, propionic acid, oxalic acid, adipic acid, maleic acid, fumaric acid, phthalic acid, and oxycarboxylic acid.

  A capacitor element in which a cathode lead layer comprising an oxide film, a solid electrolyte layer, a carbon layer, and a cathode silver layer is sequentially formed on a sintered body produced by pressure-molding and sintering a valve action metal powder, and when forming an exterior resin Then, an injection hole extending from the outer surface to the capacitor element is formed, an acidic solution is injected from the injection hole, and then an aging treatment is performed to obtain a solid electrolytic capacitor with improved leakage current characteristics and improved reliability be able to.

[Example 1]
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 shows a cross-sectional view and a partially enlarged view of a solid electrolytic capacitor in an embodiment of the present invention. First, a tantalum valve action metal powder is pressure-molded to a predetermined size and then sintered to produce a sintered body. Subsequently, the sintered body is immersed in an acidic solution such as phosphoric acid, and a voltage is applied in the solution to perform anodization to form an oxide film 4 on the surface of the sintered body. Thereafter, the solid electrolyte layer 5, the carbon layer 6, and the cathode silver layer 7 are sequentially formed on the oxide film surface. Subsequently, the cathode lead frame 10 and the cathode silver layer 7 are connected via the conductive adhesive 8, and the anode lead frame 9 and the anode lead wire 2 are connected by resistance welding. Thereafter, in order to form the injection hole 12 for injecting the acidic solution on the bottom surface of the exterior, the exterior 11 made of an epoxy resin is formed by transfer molding using a mold having a convex portion. After forming the exterior resin, an acetic acid solution having a conductivity of 10 μS / cm is injected from the injection hole. Thereafter, a voltage 1.2 times the rated voltage is applied and subjected to an aging treatment, followed by washing with water and drying to remove the acetic acid solution. Subsequently, the injection hole was sealed with an epoxy resin to produce a solid electrolytic capacitor.

[Example 2]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that after the exterior resin was formed, an acetic acid solution having a conductivity of 1 mS / cm was injected from the injection hole.

[Example 3]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that after forming the exterior resin, an acetic acid solution having a conductivity of 10 mS / cm was injected from the injection hole.

[Example 4]
After forming the exterior resin, after injecting an acetic acid solution having a conductivity of 1 mS / cm from the injection hole, applying a voltage 0.3 times the rated voltage and performing an aging treatment, a solid was obtained in the same manner as in Example 1. An electrolytic capacitor was produced.

[Example 5]
After forming the exterior resin, after injecting an acetic acid solution having a conductivity of 1 mS / cm from the injection hole, applying a voltage 2.0 times the rated voltage and performing an aging treatment, a solid was obtained in the same manner as in Example 1. An electrolytic capacitor was produced.

[Example 6]
After forming the exterior resin, after injecting an acetic acid solution having a conductivity of 1 mS / cm from the injection hole, applying a voltage 4.0 times the rated voltage and performing an aging treatment, a solid was obtained in the same manner as in Example 1. An electrolytic capacitor was produced.

[Comparative Example 1]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that after the exterior resin was formed, an acetic acid solution having an electric conductivity of 5 μS / cm was injected from the injection hole.

[Comparative Example 2]
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that after forming the exterior resin, an acetic acid solution having an electric conductivity of 20 mS / cm was injected from the injection hole.

[Comparative Example 3]
After forming the exterior resin, after injecting an acetic acid solution having a conductivity of 1 mS / cm from the injection hole, applying a voltage 0.2 times the rated voltage and performing an aging treatment, a solid was obtained in the same manner as in Example 1. An electrolytic capacitor was produced.

[Comparative Example 4]
After forming the exterior resin, after injecting an acetic acid solution having a conductivity of 1 mS / cm from the injection hole, applying a voltage 5.0 times the rated voltage and aging treatment, a solid was obtained in the same manner as in Example 1. An electrolytic capacitor was produced.

(Conventional example)
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that after the exterior resin was formed, an acetic acid solution was not injected and an aging treatment was performed.

  Regarding the solid electrolytic capacitors of Examples 1 to 6, Comparative Examples 1 to 4, and the conventional example, the leakage current values (10 V application, 1 minute value) are shown in Table 1, respectively, and the high temperature load test (85 ° C., 10 V application) FIG. 3 shows the transition of the leakage current value.

As is clear from Table 1, Examples 1 to 6 have lower leakage currents than Comparative Examples 1 to 4 and the conventional example. This is because the oxide film was repaired by aging in an acidic solution after forming the exterior resin. Here, when the electric conductivity of the acetic acid solution is 5 μS / cm or less (Comparative Example 1) and 20 mS / cm or more (Comparative Example 2), the leakage current becomes high. Therefore, the electric conductivity is desirably 10 μS / cm to 10 mS / cm.
Further, when the magnification of the aging voltage with respect to the rated voltage is 0.2 times or less (Comparative Example 3) and 5.0 times or more (Comparative Example 4), the leakage current becomes high, so the magnification is 0.3 to 4.0. Double is desirable.

  Furthermore, although the acetic acid was used for the acidic solution of the Example of this invention, even if it uses nitric acid, propionic acid, oxalic acid, adipic acid, maleic acid, fumaric acid, phthalic acid, and oxycarboxylic acid, the same effect is obtained. Obtainable.

  Moreover, although the tantalum is used for the valve action metal powder of the Example of this invention, the same effect can be acquired even if it uses niobium.

It is sectional drawing and the elements on larger scale of the solid electrolytic capacitor in an Example. It is sectional drawing and the partial enlarged view of the solid electrolytic capacitor in a prior art example. It is a high temperature load test result of Example 1 and a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Anode lead 3 Pore 4 Oxide film 5 Solid electrolyte layer 6 Carbon layer 7 Cathode silver layer 8 Conductive adhesive 9 Anode lead frame 10 Cathode lead frame 11 Exterior resin 12 Injection hole

Claims (3)

A solid formed by forming an exterior resin on a capacitor element in which a valve action metal powder is pressure-formed, an oxide film is formed on a sintered sintered body, and a solid electrolyte layer and a cathode lead layer are sequentially laminated on the oxide film. In the method of manufacturing an electrolytic capacitor,
A solid electrolytic capacitor characterized by forming an injection hole from the exterior surface to the capacitor element when forming the exterior resin, injecting an acidic solution into the injection hole, performing an aging treatment, and then sealing the injection hole Production method.   The method for producing a solid electrolytic capacitor, wherein the electrical conductivity of the acidic solution according to claim 1 is 10 μS / cm to 10 mS / cm. The method for producing a solid electrolytic capacitor, wherein the voltage of the aging treatment according to claim 1 is 0.3 to 4.0 times the rated voltage.

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