JPH04324612A - Manufacture of organic semiconductor solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To obtain a formed coat which hardly changes the amount of electric current leaking from the coat and has an excellent heat resistance, by preventing the coat from being damaged by a thermal stress and declining in recovering power caused by the damage, by reforming a metal provided with an oxide film on the surface and having a valve action with a forming solution containing saccarides. CONSTITUTION:Saccarides are added to a forming solution used for reforming a metal, such as aluminum, tantalum, niobium, etc., having a valve action and coated with an oxide film formed by anodic oxidation or anodic forming and the metal is reformed with the forming solution. Then a solid electrolytic layer is formed by cooling and solidifying TCNQ complex salt after the complex salt is melted by heating. For example, such a reforming process that produces a capacitor element 6 by putting separator paper 3 between Al anode foil 1 and its facing cathode foil 2 and winding the foil 1 and 2 to a cylindrical shape and performs heat treatment on the element 6 after dipping the element 6 in a forming solution is repeated several times. The forming solution is prepared by adding a little amount of glucose to a solvent (water) in addition to an electrolyte (ammonium adipate, etc.).

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic semiconductor solid electrolytic capacitor. More specifically, the present invention relates to an organic semiconductor solid electrolytic capacitor using a complex salt of 7,7,8,8-tetracyanoquinodimethane (hereinafter abbreviated as TCNQ complex salt) as an electrolyte.

0002

[Prior Art] Conventionally, it has been proposed to use an organic semiconductor, especially a TCNQ complex salt, as a solid electrolyte for solid electrolytic capacitors (for example, Japanese Patent Publication No. 62-52939 (1983)).
(See H01G 9/02).

[0003] In this method, after an aluminum foil and a cathode foil that have been subjected to an etching treatment and a chemical conversion treatment are wound through a separator paper, a chemical conversion liquid is applied to the cut end of the foil and to repair the defective part of the chemical conversion coating. Impregnate and reconstitute. Furthermore, in order to make the separator paper fine and to facilitate impregnation with the TCNQ complex salt, the separator paper is carbonized by heating. This reconversion and carbonization treatment is performed alternately several times. The TCNQ complex salt is then melted and impregnated into the capacitor element treated as described above to form a solid electrolytic capacitor.

[0004] In recent years, with the miniaturization of electrical equipment, TCNQ
There is also a strong demand for surface-mount capacitors using complex salts. However, this type of capacitor cannot withstand the thermal stress (usually 230 degrees Celsius) during soldering, which is essential for surface-mount components, and has the drawback of increasing leakage current, so there is a strong desire for improved heat resistance. There is.

[0005] Therefore, the present applicant first filed a patent application No. 3-76.
No. 301 (filing date: April 9, 1991) discloses the following technology.

That is, a capacitor element is immersed in a solution containing an organic hydroxy compound having a melting point of 200° C. or higher, and then the solvent is evaporated by heating to form a film of the organic hydroxy compound on the oxide film of the capacitor element. , a solid electrolytic capacitor is manufactured by impregnating a capacitor element with a heated and melted TCNQ complex salt.

[0007] In the solid electrolytic capacitor disclosed in the above-mentioned prior application, the TCNQ complex is thought to be decomposed under the influence of the organic hydroxy compound, especially at high temperatures, and this decomposition reaction causes the complex to become insulating. It is therefore presumed that the generation of leakage current in the oxide film defect portion is prevented.

[0008] Furthermore, as a method for causing an organic hydroxy compound to act on the TCNQ complex, a method of mixing the organic hydroxy compound as an additive into the TCNQ complex before impregnation can also be considered. However, in this method, TC
When the NQ complex salt is melted, it reacts rapidly and may cause foaming, which poses a practical problem.

[0009]

[Problems to be Solved by the Invention] The present invention has the above-mentioned
A heat-resistant material that improves the damage to the chemical conversion film due to mechanical and thermal stress during TCNQ complex salt impregnation or soldering and the decrease in the repair ability of the chemical conversion film caused by this, and has almost no change in leakage current. The present invention provides an excellent method for manufacturing solid electrolytic capacitors and simplifies the manufacturing process.

0010

[Means for Solving the Problems] The present invention is to recycle metals with valve action, such as aluminum, tantalum, and niobium, whose surfaces have been provided with an oxide film by anodization or anodization, using a chemical solution containing sugars. This is a method for manufacturing an organic semiconductor solid electrolytic capacitor, which is characterized in that a solid electrolyte layer is formed by performing chemical conversion, heating and melting a TCNQ complex salt, and then cooling and solidifying it.

[0011] Furthermore, it is preferable that the saccharide contains at least one of glucose and glucose polymers.

0012

[Function] Since the present invention uses the above-mentioned manufacturing method, sugars (organic hydroxy compounds) are added onto the chemical conversion coating or in the defective areas of the chemical conversion coating, without forming a hydroxy compound coating in a separate process as in the conventional method. A type of film is formed, and a capacitor with extremely low leakage current can be obtained even after heat stress such as soldering.

[0013]

[Example] Next, an example of the present invention will be described. Figure 1
As shown in FIG. 2, a separator paper (3) is sandwiched between an aluminum anode foil (1) and an opposing cathode foil (2) and wound into a cylindrical shape to produce a capacitor element (6). A re-chemical conversion process was performed several times in which this capacitor element (6) was immersed in a chemical liquid and heat treated (carbonized).

In addition to the solvent (water) and electrolyte (for example, ammonium adipate, ammonium phosphate), this chemical solution contains a small amount of sugar (for example, glucose, which is a monosaccharide, or starch, which is a glucose polymer (polysaccharide)). It is included. Its composition is shown in Table 1.

[0015]

[Table 1]

[0016] In Table 1, (C) does not contain sugars and uses a conventionally used chemical liquid.

[0017] Thereafter, a TCNQ complex salt (for example, N, N,
- A mixture of equal amounts of pentamethylenerutidinium 2.TCNQ4 and N-phenethylrutidinium.TCNQ2) is heated and melted at 320°C, impregnated with the preheated capacitor element (6), and rapidly cooled. Thereafter, the capacitor element (6) is inserted into the case (7), covered with resin (9), and subjected to voltage treatment (aging) to complete the intended capacitor as shown in FIG.

Table 2 shows the results of a reflow test (simulating heat during soldering) of a capacitor made according to the present invention and a conventional capacitor made in the same manner as the product of the present invention except that no sugar was used.
The characteristics of leakage current values before and after reflow oven (160°C x 2 minutes + 230°C x 30 seconds) are shown.

[0019]

[Table 2]

[0020] (A), (B), and (C) in Table 2 are (A) in Table 1.
(B) This capacitor was subjected to reconversion treatment using a chemical solution having the composition shown in (C), and has a rating of 16 [V] and a capacitance of 6.8 [μF].

(A) and (B) are products of the present invention, and (C) is a conventional product. Note that the leakage current value is the value after 1 minute of application of 16 [V], and shows the average value of each 10 samples.

From Table 2, it can be seen that the products of the present invention have better leakage current characteristics than the conventional products even after the Veriflow test. In this way, a capacitor with extremely low leakage current can be obtained even after thermal stress such as soldering.

Note that the present invention is not limited to the case where a wound element in which an anode foil and a cathode foil are wound through a separator paper is used as a capacitor element, but a metal powder having a valve action can be used as a capacitor element. This also applies to the case where a sintered element formed by pressure molding and sintering is used.

[0024]

[Effects of the Invention] As described above, according to the present invention, the TCNQ complex salt causes a decomposition reaction at high temperatures under the influence of sugars and becomes insulating, and the generation of leakage current in the defective portion of the oxide film on the aluminum foil is prevented. A solid electrolytic capacitor with extremely excellent leakage current characteristics can be obtained even after soldering.

[0025] Furthermore, sugars are one of the few water-soluble organic substances with low chemical reactivity, so it is unlikely that they will have a negative effect on the electrolytes in the chemical solution, and they can be used as additives in the chemical solution. suitable for Therefore, reconversion and formation of a saccharide film can be performed simultaneously, and the manufacturing process can be simplified.

[Brief explanation of drawings]

FIG. 1 is a drawing showing an example of a capacitor element.

FIG. 2 is a drawing showing an example of an organic semiconductor solid electrolytic capacitor using a TCNQ complex salt as an electrolyte.

[Explanation of symbols]

1 Anode foil 2 Cathode foil 3 Separator 4,4’ Aluminum lead 5,5’ lead wire 6 Capacitor element 7 Aluminum case 8 TCNQ complex salt 9 Resin

Claims (2)

[Claims] Claim 1: Sugars are added to a chemical solution for reconforming metals with valve action, such as aluminum, tantalum, and niobium, whose surfaces have been provided with an oxide film by anodic oxidation or anodization; A method for manufacturing an organic semiconductor solid electrolytic capacitor, characterized in that the metal is reformed by heating and the TCNQ complex salt is heated and melted, and then cooled and solidified to form a solid electrolyte layer. 2. The method for manufacturing an organic semiconductor solid electrolytic capacitor according to claim 1, wherein the saccharide contains at least one of glucose and a glucose polymer.