JPH02305428A - Solid electrolytic capacitor and manufacture thereof - Google Patents

Abstract

PURPOSE:To manufacture the title capacitor miniaturized and having excellent high-frequency characteristics by densely forming thin film comprising a conductive organic material by Langmuir-Blodgett's technique. CONSTITUTION:An insulating oxide film layer to be a dielectric layer 2 is formed on an electrode 1 comprising a metal displaying insulating oxide film forming activity. Then, one or more layers of Ni(dmit)2 complex 5 (LB film) using ammonium comprising at least one each of methyl radical and long-chain alkyl radicals as solid electrolyte layer as counteraction are laminated on the surface by Langmuir-Blodgett's(LB) technique and then an electric leading-out means (cathode lead) 7 and a counter electrode is provided on the outer surface. This LB thin film 5 is not only in a thin layer but also in high denseness and conductivity. Through these procedures, the title solid electrolytic capacitor miniaturized but in large capacitance and having excellent electrical characteristics can be manufactured.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a solid electrolytic capacitor using a conductive organometallic compound thin film as an electrolyte, and a method for manufacturing the same.

[Conventional technology]

Solid electrolytic capacitors use a group of metals that have the ability to form a film, such as aluminum, tantalum, and niobium, on which an insulating oxide film layer is formed, so-called valve metals, as the anode. Forms an oxide film layer of
An electrolyte layer is provided on the outer surface of the electrolyte layer, and an electrode portion for drawing out the shade is further provided on the outside of the electrolyte layer. For solid electrolytes, attempts have been made to use metal oxides such as manganese dioxide and lead dioxide, or conductive polymers such as tetracyanoquinodimethane complex salts, polyacetylene, and polypyrrole. These conductive compounds have a certain degree of conductivity and can realize the characteristics of a solid electrolytic capacitor. By the way, solid electrolytic capacitors in recent years are required to be smaller, thinner, and have improved electrical characteristics due to demands for combination with semiconductor products and chip formation. However, the current situation is that conventional solid electrolyte formation cannot sufficiently meet these demands. From this point of view, the Langmuir-Projet method (LB) has recently been used to form the electrolyte layer of solid electrolytic capacitors.
Attempts have been made to form a thin film electrolyte layer using a method (for example, Japanese Patent Application Laid-open No. 122207/1983,
10611, etc.). However, it is not always easy to simultaneously form a thin film and improve electrical characteristics. In particular, if the conductivity of a complex compound formed as a thin film is insufficient, sufficient values cannot be obtained for capacitor loss, equal series resistance, impedance characteristics at high frequencies, etc. Furthermore, if there are defects in the thin film or if a dense film is not formed, problems such as short circuits and increased leakage current will occur.

[Problem to be solved by the invention]

The present invention relates to a capacitor using a Langmuir-Prodgett film (LB film), which is an organic conductive complex, as a solid electrolyte, and a method for manufacturing the same, which aims to reduce the size and increase the capacity, and to produce a solid electrolytic capacitor with excellent electrical characteristics. The purpose is to obtain.

[Means to solve the problem]

The solid electrolytic capacitor of the present invention uses a metal capable of forming an insulating oxide film as an electrode, and has at least one methyl group as a solid electrolyte layer on the surface of the electrode on which an insulating oxide film layer serving as a dielectric layer is formed. N with ammonium as a counter cation consisting of and multiple long-chain alkyl groups
i (dmit). It is characterized in that one or more layers of the complex are laminated by the Langmuir-Prodgett method, and furthermore, electrical extraction means as a counter electrode is provided on the outer surface of the complex. In addition, the method for manufacturing a solid electrolytic capacitor of the present invention uses a metal capable of forming an insulating oxide film as an electrode, and a long-chain alkyl ammonium is added to the surface of the electrode on which an oxide film layer serving as a dielectric layer is formed as a counter cation. N
i (ditL)z A mixture of the If form and saturated fatty acid is spread on the water surface and layered using the Langmuir-Prodgett method, and then chemical oxidation or electrolytic oxidation treatment is applied to increase the conductivity, and the outer surface is It is characterized by being provided with an electrical extraction means as a counter cathode. More than 10 types of material systems have already been reported as conductive LB films, but most belong to one-dimensional organic conductors, are extremely susceptible to defects in the conductive stack, and have concerns specific to the -dimensionality. Since it has a certain property, it is not suitable as an electrolyte for solid electrolytic capacitors, which require long-term stability. On the other hand, as an acceptor [metal] (d+ait
) z and a long-chain alkyl ammonium as a countercation forms a highly dimensional complex and can be suitable for the purpose of this invention. As a method for producing such a complex, for example, 5ynth
, Net, ,27. P2O3 (198B) or C
hemistry Letters P2S5-368
(1989) and others. The metal dmiL complex has a general formula: %Formula %) The complex is composed of ammonium consisting of at least one methyl group and a plurality of long-chain alkyl groups on the counter cation side. Further, in this invention, the metal element M is nickel. For the alkyl group on the counter cation side, one methyl group and a long chain alkyl group of, for example, about C=10 may be selected, and depending on the valence of the nitrogen atom, two or three of the above long chains may be selected. Bonding of alkyl groups is possible, and each can take the form of an amine or a quaternary ammonium. A specific example of such a compound is tridecylmethylammonium, and the structural formula of this complex is as follows. In order to form LBIII from this complex, this complex is mixed with an equimolar amount of a saturated fatty acid such as arachidic acid, and this mixture is dispersed on the water surface to form an LB film, and the electrode surface of the capacitor is and bromine gas (Br
The desired solid electrolyte can be obtained by increasing the electrical conductivity by performing chemical oxidation by exposing it to a halogen such as lithium perchlorate, or by performing electrolytic oxidation in an aqueous solution of peroxide such as lithium perchlorate (LiCffiO,). . By the process described above, in the case of the complex of tridecylmethyl, for example, LB
When about 20 layers of film are formed, it takes 1.0 to 1.37 seconds.
A thin film with a conductivity of /cm is obtained. As for the means for forming the LB film on the electrode surface, known means can be used, but for example, as shown in FIG.
LB consisting of a mixture of Ni(dmH)t 1f and saturated fatty acids such as arachidic acid is placed on the surface of the water 14 of the aquarium 10.
A plate-shaped electrode 12 made of aluminum or the like, which has been developed with Bi12 and has been immersed in a water tank 10 at right angles, and has a dielectric oxide film layer formed on its surface for a capacitor, is placed in a water tank 10.
LB is formed on the surface of the plate electrode 12 by pulling it up from the
The I pattern 11 can be fixed. Furthermore, the float 13 is
It is installed to smoothly fix LBIIxII to the plate-shaped electrode 12, and the float 14 moves toward the plate-shaped electrode 12 as the plate-shaped electrode 12 is pulled up. As described above, the electrode 12 on which the LBBi 12 is fixed is subjected to chemical oxidation or electrolytic oxidation to obtain a desired degree of conductivity, and then a conductive means for forming a counter electrode is formed on its surface. Specifically, gold, silver, copper,
A metal such as nickel or aluminum may be vapor-deposited and used directly as an electrode, or electrically connected to an electrode such as a separately processed metal plate via a conductive paste containing fine metal particles. Further, if necessary, it is possible to leave the electrical connection part with the outside and store it in an exterior case or seal it with exterior resin.

[For production]

According to this invention, N i (d
mit), a complex LB film is formed as a solid electrolyte layer on top of the dielectric oxide film layer of the electrode. This LB thin film becomes an extremely thin layer, and
Since it has high density and high conductivity, when used as a solid electrolytic capacitor, it has excellent electrical characteristics and can be made smaller and thinner.

【Example】

The present invention will be explained below based on examples. FIG. 1 is a sectional view showing the structure of a solid electrolytic capacitor according to an embodiment of the present invention. First, a high-purity (99.99%) aluminum thin plate 1 is prepared as an electrode, and after surface enlargement treatment by electrolytic etching, a dielectric layer 2 of aluminum oxide is formed on the surface by anodizing treatment at a voltage of 200V. The electrode 1 was formed except for one end. An anode lead 4 was connected to the unformed portion 3 of the electrode dielectric layer 2 by welding. Next, tridecylammonium-N i (dmit)
The forming part of the dielectric layer 2 of the electrode 1 was immersed in a 1:1 mixed solution of the z complex and arachidic acid spread in water, and then pulled up to fix the LB film 5 on the surface of the electrode foil. . The formation area of the LB film 5 was 25 mm x 40 mm. This electrode 1 was exposed to bromine gas for 10 minutes to perform chemical oxidation and impart electrical conductivity. Repeat this process 20 times, L
The B film 5 had 20 layers. In this state, the electrical conductivity of the LB film 5 on the surface was measured by a four-terminal method, and the value was 1.28 S/cm. Next, a conductive paste (Electrodac, manufactured by Acheson Japan) 6 was applied to the surface of this LB film 5, and a cathode lead 7 was fixed thereon. The outer surface of this capacitor element was coated with exterior resin 8 and the element portion was sealed to complete the capacitor. Next, for comparison with this capacitor, we created a capacitor using manganese dioxide as a solid electrolyte and compared its characteristics. A manganese dioxide capacitor uses an electrode l with the same specifications as the capacitor of this invention for the aluminum anode, and repeats the process five times to apply a manganese nitrate aqueous solution to the same surface area and denature it into manganese dioxide by firing it. Carbon paste was applied, and silver paste was further applied to the outer surface to connect the cathode lead. The results of investigating the electrical characteristics of these solid electrolytic capacitors are shown in the table below. As can be seen from the results, the solid electrolytic capacitor of the present invention has a higher capacitance value per unit area than conventional capacitors, and is advantageous for miniaturization and thinning. In addition, the low loss value and equal series resistance value at high frequencies mean that
This indicates that the electrolyte layer has high conductivity.

【Effect of the invention】

As described above, according to the present invention, a thin film of conductive organic material can be formed densely and thinly by the LB method, so that it is possible to create a solid electrolytic capacitor that is smaller and has superior high frequency characteristics compared to conventional solid electrolytic capacitors. Obtainable.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the solid electrolytic capacitor of the present invention, and FIG. 2 is an explanatory view showing a method of forming an LB film. DESCRIPTION OF SYMBOLS 1... Electrode, 2... Dielectric layer, 3... Unformed part 4
... Anode lead, 5... LB film 6... Conductive paste, 7... Cathode lead 8... Exterior resin. Figure 1 Figure 2

Claims (2)

[Claims] (1) A metal capable of forming an insulating oxide film is used as an electrode, and an insulating oxide film layer serving as a dielectric layer is formed on the electrode, and at least one methyl group and a plurality of long chains are formed as a solid electrolyte layer on the surface of the electrode. One layer or multiple layers of Ni(dmit)_2 complex with ammonium consisting of an alkyl group as a counter cation are laminated by the Langmuir-Prodgett method, and an electrical extraction means as a counter electrode is provided on the outer surface. Characteristic solid electrolytic capacitors. (2) A metal capable of forming an insulating oxide film is used for the electrode, and at least one methyl group and a plurality of long-chain alkyl groups are formed on the surface of the electrode on which the insulating oxide film layer serving as the dielectric layer is formed. A mixture of Ni(dmit)_2 complex with ammonium as a countercation and saturated fatty acid is spread on the water surface, and one or more layers are laminated by the Langmuir-Prodgett method, and then chemical oxidation or electrolytic oxidation treatment is performed. 1. A method for manufacturing a solid electrolytic capacitor, which is characterized in that the conductivity is increased by coating the solid electrolytic capacitor with electrical conductivity, and further, electrical lead-out means as a counter electrode is provided on the outer surface of the solid electrolytic capacitor.