JPH04364017A - Organic semiconductor solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To substantally completely prevent a leakage current from being changed by forming an aromatic nitro compound coated film on a metal having a valve action, and further forming a solid electrolytic layer on the coated film by cooling and solidifying TCNQ complex salt after heating and melting of the same. CONSTITUTION:An aluminum foil after making etching and formation is used as an anode foil 1. Manila paper is held as a separator 3 between the anode foil 1 and an opposite cathode foil 2, and is wound into a cylinder shape. Hereby, a capacitor device 6 is formed by winding the separator 3 inserted between both electrodes and the anode foil 1 and the cathode foil 2 where an oxide coated film is formed on the aluminum foil. The capacitor device 6 is dipped in a methanol solution of any aromatic nitro compound, and is dried. Thereafter, TNC complex salt is heated and dissolved whereby the preheated capacitor device 6 is impregnated and annealed. Thereafter, the device is covered with resin and is subjected to a voltage treatment to complete a capacitor. Hereby, a leakage current characteristic is stabilized even after soldering.

Description

[Detailed description of the invention]

0001

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

0002

[Prior Art] Conventionally, it has been proposed that solid electrolytic capacitors use an organic semiconductor, especially a highly conductive TCNQ complex salt, as a solid electrolyte (for example, Japanese Patent Publication No. 62-529
(See Publication No. 39 (H01G 9/02)). An aluminum solid electrolytic capacitor using such a TCNQ complex salt has significantly improved frequency characteristics and temperature characteristics, far exceeding those of conventional dry capacitors.

0003

[Problems to be Solved by the Invention] In recent years, with the miniaturization of electrical equipment, there has been a strong demand for capacitors using TCNQ complex salts for surface mounting. 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.

[0004] The present invention provides a solid electrolytic capacitor with excellent heat resistance in which the leakage current hardly changes even under the heat stress during soldering as described above.

[0005]

[Means for Solving the Problems] The inventions of Examples 1 and 3 provide an aromatic nitro compound on a metal having a valve action, such as aluminum, tantalum, or niobium, on which an oxide film is formed on the surface by anodization or anodization. The organic semiconductor solid electrolytic capacitor is characterized in that a solid electrolyte layer is formed on the aromatic nitro compound film by heating and melting a TCNQ complex salt and then cooling and solidifying it.

[0006] In addition, the inventions of Examples 2 and 3 apply T to a metal having a valve action, such as aluminum, tantalum, or niobium, on which an oxide film is formed on the surface by anodization or anodization.
This organic semiconductor solid electrolytic capacitor is characterized in that a mixture of a CNQ complex salt and an aromatic nitro compound is heated and melted, then cooled and solidified to form a solid electrolyte layer.

At this time, the aromatic nitro compound is preferably dinitrobenzene.

[0008] Furthermore, the invention of Embodiment 4 is made of aluminum having an oxide film formed on its surface by anodization or anodization.
A vegetable rubber film is formed on a metal with valve action such as tantalum or niobium, and TCN is applied on the vegetable rubber film.
This is an organic semiconductor solid electrolytic capacitor characterized in that a Q complex salt is heated and melted, then cooled and solidified to form a solid electrolyte layer.

[0009] In addition, the invention of Embodiment 5 provides TCNQ on a metal having a valve action, such as aluminum, tantalum, or niobium, on which an oxide film is formed on the surface by anodization or anodization.
This organic semiconductor solid electrolytic capacitor is characterized in that a solid electrolyte layer is formed by heating and melting a mixture of a complex salt and a plant gum substance, and then cooling and solidifying the mixture.

[0010] At this time, the vegetable gum substance is gum arabic,
It is preferable that at least one of guar gum, karaya gum, and tragacanth gum is included.

[0011]

[Function] The inventions of Examples 1 to 3 use an aromatic nitro compound having an electron removing action. For this reason, TCNQ
It is thought that the hydrogen in the complex salt is sucked and the decomposition of the TCNQ complex salt is suppressed. As a result, it is presumed that a capacitor with stable leakage current characteristics can be obtained even after soldering.

[0012] Furthermore, defects in the oxide film are considered to be a cause of the increase in leakage current. Therefore, in the inventions of Examples 4 and 5, since vegetable rubber is used, if there is a defective part of the oxide film of the anode foil in the capacitor element, if Joule heat is generated in the defective part, the vegetable rubber T depending on quality
It is presumed that the decomposition reaction of the CNQ complex salt progresses, resulting in partial insulation. Therefore, it seems possible to realize a capacitor with stable leakage current characteristics even after soldering.

[0013]

[Example] Next, an example of the present invention will be described.

FIG. 1 shows a capacitor element used in the present invention. First, a high-purity (99.99% or higher) aluminum foil is roughened by chemical treatment, and a so-called etching treatment is performed to increase the effective surface area. Next, an oxide film (
forming a thin film of aluminum oxide (chemical conversion treatment). Next, the etched and chemically treated aluminum foil is used as an anode foil 1, manila paper is sandwiched between it and a counter cathode foil 2 as a separator 3, and the aluminum foil is rolled up into a cylindrical shape as shown in FIG. In this way, a capacitor element 6 is formed by winding the anode foil 1 and the cathode foil 2, which are aluminum foils with an oxide film formed thereon, and the separator 3 inserted between the two electrode foils. Note that 4 and 4' are aluminum leads, and 5 and 5' are lead wires.

Furthermore, the capacitor element 6 is subjected to heat treatment and reconversion treatment, and the manila paper constituting the separator 3 is carbonized to reduce the density by reducing the diameter of the fibers.

[0016] As a separator, Manila paper that has been heat-treated and carbonized at a predetermined temperature and time (for example, 240°C for 40 minutes) or a carbon non-woven fabric can be used.
It may be sandwiched and wound between an anode foil and a cathode foil.

(Example 1) First, the wound capacitor element 6 manufactured as described above was immersed in a 2% methanol solution of an aromatic nitro compound (for example, dinitrobenzene).
Dry at 5°C. Then TCNQ complex salt (e.g., N,N
,-pentamethylenerutidinium 2・TCNQ4 and N-
A mixture of equal amounts of phenethylrutidinium/TCNQ2) is heated and melted at 300°C, impregnated into the preheated capacitor element 6, and rapidly cooled. After that, it is covered with resin and voltage treated (
aging) to complete the desired capacitor.

(Example 2) First, TCNQ complex salt and dinitrobenzene of 4% by weight of this complex salt are mixed uniformly. Then, the mixture is heated and melted at 300° C., impregnated with the preheated capacitor element 6, and rapidly cooled. After that, it is packaged with resin and subjected to voltage treatment (aging) to complete the desired capacitor.

(Example 3) First, the wound capacitor element 6 manufactured as described above is immersed in a 2% methanol solution of dinitrobenzene and dried at 85°C. Then TCN
A mixture of Q complex salt and 4 weight percent dinitrobenzene of the complex salt is heated and melted at 300° C., impregnated into the preheated capacitor element 6, and rapidly cooled. After that, it is packaged with resin and subjected to voltage treatment (aging) to complete the desired capacitor.

Table 1 shows the results of capacitance and leakage current before and after a reflow test assuming heat during soldering during surface mounting for products of the present invention and conventional products according to Examples 1, 2, and 3. show.

[0021]

[Table 1]

[0022] This reflow test is a test in which a capacitor is held at 160°C for 2 minutes in a reflow oven, and then held at 230°C for 30 seconds.

In Table 1, all capacitors are rated 2
5V, capacity 1.5μF, solid electrolyte is N,N,-
A mixture of equal amounts of pentamethylenerutidinium 2.TCNQ4 and N-phenethylrutidinium.TCNQ2 is used.

In view of the melting temperature of the TCNQ complex salt, the aromatic nitro compound preferably has a boiling point of 250° C. or higher.

(Example 4) First, the wound type capacitor element 6 manufactured as described above is made of vegetable rubber (for example, gum arabic, gum guar, gum karaya, gum tragacanth).
and dried at 85°C. Thereafter, a TCNQ complex salt (e.g., a mixture of equal amounts of N,N,-pentamethylenerutidinium 2.TCNQ4 and N-phenethyrutidinium.TCNQ2) is heated and melted at 320° C., and the preheated capacitor element 6 is impregnated with it. Cool quickly. After that, it is packaged with resin and subjected to voltage treatment (aging) to complete the desired capacitor.

(Example 5) First, TCNQ complex salt and 2% by weight of the complex salt of vegetable gum are mixed uniformly. Then, the mixture is heated and melted at 320° C., impregnated with the preheated capacitor element 6, and rapidly cooled. After that, it is packaged with resin and subjected to voltage treatment (aging) to complete the desired capacitor.

Table 2 shows the results of capacitance and leakage current before and after a reflow test assuming heat during soldering during surface mounting for products of the present invention according to Examples 4 and 5 and conventional products.

[0028]

[Table 2]

In Table 2, all capacitors are rated 1
The solid electrolyte used was a mixture of equal amounts of N,N,-pentamethylenerutidinium 2.TCNQ4 and N-phenethylrutidinium.TCNQ2.

Examples (4a) to (4b) are capacitors according to the fourth embodiment described above, and Examples (5a) to (5b) are capacitors according to the fifth embodiment described above.

[0031] In addition, tan δ [%] (120 Hz
) is the tangent of the loss angle.

[0032] The vegetable rubber used in the present invention is not limited to that used in the above-mentioned embodiments, but can be applied to the residual heat of the element during impregnation with the TCNQ complex salt or the heat during the melting of the TCNQ complex salt. It goes without saying that similar effects can be obtained with other plant gums as long as they are durable.

[0033]

Effects of the Invention From Tables 1 and 2 above, it is clear that the organic semiconductor solid electrolytic capacitor according to the present invention has excellent leakage current characteristics even after the reflow test. That is, it is possible to realize an organic semiconductor solid electrolytic capacitor with extremely excellent leakage current characteristics even after soldering.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a capacitor element used in the present invention.

[Explanation of symbols]

1 Anode foil 2 Cathode foil 3 Separator 6 Capacitor element

Claims (6)

[Claims] Claim 1: A film of an aromatic nitro compound is formed on a metal having a valve action, such as aluminum, tantalum, or niobium, on which an oxide film is provided on the surface by anodization or anodization, and the film of the aromatic nitro compound is formed. An organic semiconductor solid electrolytic capacitor characterized in that a solid electrolyte layer is formed by heating and melting a TCNQ complex salt and then cooling and solidifying the TCNQ complex salt. [Claim 2] A mixture of a TCNQ complex salt and an aromatic nitro compound is heated and melted on a valve metal such as aluminum, tantalum, or niobium, on which an oxide film is formed on the surface by anodization or anodization, and then cooled and solidified. An organic semiconductor solid electrolytic capacitor characterized by forming a solid electrolyte layer. 3. The organic semiconductor solid electrolytic capacitor according to claim 1, wherein the aromatic nitro compound is dinitrobenzene. 4. A vegetable rubber film is formed on a metal having a valve action such as aluminum, tantalum, or niobium, which has an oxide film on its surface by anodizing or anodizing,
An organic semiconductor solid electrolytic capacitor characterized in that a solid electrolyte layer is formed on the vegetable rubber film by heating and melting a TCNQ complex salt and then cooling and solidifying it. 5. A mixture of TCNQ complex salt and vegetable rubber is heated and melted on a valve metal such as aluminum, tantalum, or niobium, which has an oxide film formed on its surface by anodization or anodization, and then cooled and solidified. An organic semiconductor solid electrolytic capacitor characterized by forming a solid electrolyte layer. 6. The organic semiconductor solid electrolytic capacitor according to claim 4, wherein the vegetable gum contains at least one of gum arabic, gum guar, gum karaya, and gum tragacanth.