JP2006024707A - Solid electrolytic capacitor and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor that has a high rate of capacitance impregnation, is compact, has large capacitance, and has improved electric characteristics in the solid electrolytic capacitor using TCNQ complex salt for a cathode layer, and to provide a method for manufacturing the solid electrolytic capacitor. <P>SOLUTION: In the solid electrolytic capacitor, the cathode layer made of normal temperature fused salt in which a decomposition point illustrated by 1-butylpyridinium salt and/or 1-ethyl-3-methylimidazolium salt is at least at 300°C, and the TCNQ complex salt is formed. In the solid electrolytic capacitor, the cathode layer is formed by impregnating the normal temperature fused salt in a capacitor element and then dipping it in the melted solution of the TCNQ complex salt, or dipping it in the mixed fused solution of the normal temperature melted salt and the TCNQ complex salt. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a small-sized and large-capacity solid electrolytic capacitor and a method for manufacturing the same, and more specifically, to a capacitor element in which an anode foil formed with a dielectric oxide film and a counter cathode foil are wound through a separator. , 7,7,8,8-tetracyanoquinodimethane (hereinafter abbreviated as “TCNQ”) complex cathode and a method of manufacturing the same.

  Conventionally, various solid electrolytic capacitors using an organic semiconductor TCNQ complex salt or a conductive polymer as a cathode layer have been proposed. These cathode layers are also referred to as solid electrolytes, and act as true cathodes as with the electrolytes of conventional electrolyte type capacitors.

  In Patent Document 1, a complex salt of N-alkyl-substituted isoquinoline and TCNQ is melted and liquefied on an anode foil, and a capacitor element is impregnated in the melt, followed by cooling and solidification to form a cathode layer. A solid electrolytic capacitor is disclosed.

  In recent years, with the downsizing of electronic equipment, capacitor characteristics are required to have a small size and large capacity. As a countermeasure, a solid electrolytic capacitor uses an anode foil whose surface has a high magnification.

  In general, in order to obtain a high-capacity solid electrolytic capacitor using an anode foil whose surface has a high magnification, it is necessary to sufficiently fill the solid electrolyte in fine pores on the surface. It is known that when the filling is insufficient, the capacity impregnation rate (percentage of the capacitance value when using the solid electrolyte with respect to the capacitance value when using the electrolytic solution) decreases.

  Solid electrolytic capacitors are superior in high frequency characteristics compared to electrolytic capacitors, have a relatively simple manufacturing process, and provide an inexpensive capacitor. However, the capacity impregnation rate is still insufficient, and the surface has a high magnification. The characteristics of the anode foil thus made are not sufficiently drawn out, and there remains a problem to be improved in terms of electrical characteristics such as capacitance and dielectric loss.

JP 58-191414 A

  An object of the present invention is to provide a solid electrolytic capacitor using a TCNQ complex salt as a cathode layer, a high capacity impregnation rate, a small size, a large capacitance, and excellent electrical characteristics, and a method for manufacturing the same. Is to provide.

  As a result of intensive studies, the present inventors have found that a solid electrolytic capacitor in which a cathode layer made of a room temperature molten salt and a TCNQ complex salt can solve the above problems, and has completed the present invention.

  That is, the present invention is a solid electrolytic capacitor characterized in that a cathode layer made of a room temperature molten salt and a TCNQ complex salt is formed on an anode foil on which a dielectric oxide film is formed.

  In addition, the present invention provides the solid electrolytic capacitor, wherein the room temperature molten salt is 1-butylpyridinium salt and / or 1-ethyl-3-methylimidazolium salt.

  The present invention is also a solid electrolytic capacitor, wherein the room temperature molten salt is a room temperature molten salt having a decomposition temperature of at least 300 ° C.

  Furthermore, the present invention provides a capacitor element in which an anode foil on which a dielectric oxide film is formed and a counter cathode foil are wound through a separator, impregnated with a room temperature molten salt, and then melted and liquefied TCNQ. A method for producing a solid electrolytic capacitor comprising: dipping in a complex salt; and cooling and solidifying the TCNQ complex salt to form a cathode layer composed of a room temperature molten salt and a TCNQ complex salt on the anode foil. .

  In addition, the present invention immerses a capacitor element in which an anode foil having a dielectric oxide film formed thereon and a counter cathode foil are wound via a separator in a mixed melt of room temperature molten salt and TCNQ complex salt. Then, the mixed solution is cooled and solidified, and a cathode layer made of a room temperature molten salt and a TCNQ complex salt is formed on the dielectric oxide film.

  The present invention is also the method for producing a solid electrolytic capacitor, wherein the room temperature molten salt is any one of 1-butylpyridinium salt and / or 1-ethyl-3-methylimidazolium salt.

  The present invention is also a method for producing a solid electrolytic capacitor, wherein the room temperature molten salt is a room temperature molten salt having a decomposition temperature of at least 300 ° C.

  The present invention is a solid electrolytic capacitor in which a cathode layer made of a room temperature molten salt and a TCNQ complex salt is formed, and the cathode layer formed by the present invention has hitherto been insufficiently filled with a solid electrolyte only with a TCNQ complex salt. Because the molten salt at room temperature can be sufficiently infiltrated into the etching pores on the surface of the anode foil that has been increased in magnification, it has a high capacity impregnation rate, is small, has a large capacitance, and has excellent electrical characteristics. An electrolytic capacitor is obtained, and the room temperature molten salt used in the present invention has a high decomposition temperature, so that a solid electrolytic capacitor excellent in heat resistance and durability can be provided.

  Moreover, according to the method for producing a solid electrolytic capacitor of the present invention, the solid electrolytic capacitor having the cathode layer can be easily and efficiently produced.

  The solid electrolytic capacitor of the present invention is obtained by forming a cathode layer made of a room temperature molten salt and a TCNQ complex salt on an anode foil on which a dielectric oxide film is formed.

  Examples of the anode foil include a metal foil made of a film-forming metal simple substance such as aluminum, tantalum, titanium, zirconium, niobium or an alloy thereof, and after etching the metal foil, a dielectric oxide film is formed by chemical conversion treatment. To be used.

  The room temperature molten salt used in the present invention is also called an ionic liquid, and is a salt that is liquid around room temperature and consists of a cation component and an anion component. Examples of the cation component include alkylammonium, alkylphosphonium, alkylpyridinium, alkylimidazolium, and examples of the anion component include tetrafluoroboric acid, hexafluorophosphoric acid, trifluoromethanesulfonic acid, trifluoromethanesulfonimide, and cyclic. Examples thereof include perfluoroalkylene imide and hydrofluoride.

  Examples of the compound include 1-butylpyridinium tetrafluoroboric acid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonimide, and trimethylhexyl ammonium hexafluorophosphoric acid.

  In general, a solid electrolytic capacitor using a TCNQ complex salt as a cathode may be exposed to a high temperature during the manufacturing process or mounting, and is required to have heat resistance from the viewpoint of extending the life. Therefore, a room temperature molten salt having excellent heat resistance, that is, a room temperature molten salt having a decomposition temperature of at least 300 ° C. is preferable, and in particular, 1-butylpyridinium salt and / or 1-ethyl-3- having a decomposition temperature of about 400 ° C. Methyl imidazolium salt is preferred.

  As the TCNQ complex salt used in the present invention, a conventionally known TCNQ complex salt can be used. For example, an isoquinoline TCNQ complex salt represented by the general formula [1] substituted at the N-position or a general formula [2] is used. Rutidinium TCNQ complex salt. Specific examples of isoquinoline TCNQ complex salts include Nn-butylisoquinolinium TCNQ and Nn-isoamylisoquinolinium TCNQ. Examples of lutidinium TCNQ complex salts include N, N′-octamethylene. -Di-3,5-lutidinium TCNQ and the like.

  In general formula [1], n represents a positive integer of 1 to 20.

  In general formula [2], n represents a positive integer of 1-20.

  The solid electrolytic capacitor of the present invention is formed with a cathode layer composed of a room temperature molten salt and a TCNQ complex salt.Hereinafter, as an example of the method for producing the solid electrolytic capacitor of the present invention, an aluminum foil is used as the anode metal, This will be described in detail.

  First, after etching the aluminum foil which is an anode foil, a chemical conversion treatment is performed to form a dielectric oxide film. In practicing the present invention, it is preferable to use a foil having a large etching magnification, whereby a capacitor having a large capacitance can be obtained.

  As the counter cathode foil, a metal foil of the same kind as the above anode foil can be used, and a separator such as manila paper is sandwiched between the anode foil and the counter cathode foil, wound into a cylindrical shape, and then subjected to heat treatment. The separator is carbonized to prepare a capacitor element.

  In a first embodiment of the method for producing a solid electrolytic capacitor of the present invention, the capacitor element is immersed in a room temperature molten salt, and the room temperature molten salt is sufficiently contained in the refined etching pores on the surface of the aluminum foil. Manufacturing of a solid electrolytic capacitor characterized by impregnating and then immersing in a melted and liquefied TCNQ complex salt, followed by cooling and solidification to form a cathode layer made of a room temperature molten salt and a TCNQ complex salt on the anode foil Is the method.

  In the above manufacturing method, the surface of the anode aluminum foil is first roughened by etching, and then the anode lead is connected, followed by chemical conversion treatment in an aqueous solution such as diammonium adipate to form a dielectric oxide film. Let

  Separately, a separator such as manila paper is sandwiched between the opposing aluminum cathode foil, to which the cathode lead is connected, and the anode foil, wound up in a cylindrical shape, and then heat treated to carbonize the separator to form a capacitor element. prepare.

  Next, after immersing the capacitor element in the room temperature molten salt solution exemplified above, the room temperature molten salt adhering excessively is lightly wiped using a nonwoven fabric or the like.

  Next, a necessary amount of powdered TCNQ complex salt is packed in a separately prepared cylindrical aluminum capacitor case with a bottom and heated to a temperature of 250 to 320 ° C. to melt and liquefy the TCNQ complex salt in the capacitor case. .

  Next, the room temperature molten salt impregnated capacitor element heated in advance is immersed in the melted and liquefied TCNQ complex salt, and then immediately cooled and solidified to form a cathode layer composed of the room temperature molten salt and the TCNQ complex salt.

  Next, the capacitor case is sealed with an epoxy resin or the like, and a voltage is applied to perform aging to complete the solid electrolytic capacitor of the present invention.

  According to a second embodiment of the method for producing a solid electrolytic capacitor of the present invention, the capacitor element is immersed in a mixed molten solution of a room temperature molten salt and a TCNQ complex salt, and then the molten solution is cooled and solidified to form an anode foil. A production method is characterized in that a cathode layer comprising a room temperature molten salt and a TCNQ complex salt is formed on the top.

  In the above manufacturing method, first, 0.1 to 30% by mass of a room temperature molten salt with respect to a required amount of powdered TCNQ complex salt and TCNQ complex salt is packed into a bottomed cylindrical aluminum capacitor case, and a temperature of 250 to 320 ° C. To melt and liquefy the room temperature molten salt and the TCNQ complex salt in the capacitor case.

  If the content of the room temperature molten salt is less than 0.1% by mass relative to the TCNQ complex salt, the effect of improving the capacity impregnation rate is insufficient, and if it exceeds 30% by mass, the electrical characteristics of the capacitor may be deteriorated. Yes, it is inconvenient.

  Next, after the preheated room temperature molten salt-impregnated capacitor element is immersed in the above-mentioned room temperature molten salt and TCNQ complex salt mixed melt, it is immediately cooled and solidified to form a cathode layer composed of the room temperature molten salt and the TCNQ complex salt. It is formed.

  Next, the capacitor case is sealed with an epoxy resin or the like, and a voltage is applied to perform aging to complete the solid electrolytic capacitor of the present invention.

  According to the above method for producing a solid electrolytic capacitor, the room temperature molten salt penetrates into the fine etching holes of the anode foil without gaps, and further, a cathode layer made of a TCNQ complex is formed. A solid electrolytic capacitor having a small size, large capacitance, and excellent electrical characteristics can be obtained. The solid electrolytic capacitor of the present invention has a higher capacity impregnation rate than a conventional capacitor using only a TCNQ complex salt as a cathode. Small size, large capacity and excellent electrical characteristics.

  Hereinafter, the present invention will be described in detail based on examples. In addition, this invention is not limited at all by the Example. In the examples, “%” represents “% by mass”, the capacitance (C) and dielectric loss (tan δ) were measured at 120 Hz, and the equivalent series resistance (ESR) was measured at 100 kHz. The volume impregnation rate was measured based on the capacitance in a 15% ammonium adipate aqueous solution.

Example 1
After roughening the surface of the aluminum foil by etching, the anode lead is connected by caulking, and then subjected to chemical conversion treatment in a 10% diammonium adipate aqueous solution at a voltage of 4 V, and a dielectric oxide film is formed on the surface. Formed.

  Next, 50 μm thick Manila paper is sandwiched as a separator between the anode foil and the opposing aluminum cathode foil to which the cathode lead is connected by resistance welding, and wound into a cylindrical shape, and then at a temperature of 400 ° C. for 4 minutes. Then, heat treatment was performed to carbonize the manila paper to produce a capacitor element. The capacitance of the obtained capacitor element in an aqueous solution was 40 μF.

Next, 1-ethyl-3-methylimidazolium tetrafluoroboric acid (hereinafter abbreviated as “EMI-BF ₄ ”, decomposition point: about 391 ° C.), which is a room temperature molten salt, is collected in a container, The capacitor element prepared above was immersed for 1 minute at room temperature, and then the excess solution was lightly wiped with a nonwoven fabric.

  Next, 60 mg of Nn-butylisoquinolinium TCNQ complex salt (hereinafter abbreviated as “BIQ-TCNQ”) is packed in a bottomed cylindrical aluminum capacitor case (diameter 6 mmφ × height 7 mm). The capacitor case was placed on a hot plate having a temperature of 300 ° C., and the charge transfer complex salt in the case was melted and liquefied.

  Next, a preheated capacitor element impregnated with a room temperature molten salt was immersed in the TCNQ complex salt melt, and then immediately cooled and solidified to form a cathode layer composed of the room temperature molten salt and the TCNQ complex salt.

  Next, the capacitor case was sealed with an epoxy resin, and aging was performed by applying a voltage of 4 V to both electrodes to complete a solid electrolytic capacitor.

  Table 1 shows the initial electrical characteristics, the capacity impregnation rate, and the electrical characteristics after high-temperature loading (held in an atmosphere at a temperature of 260 ° C. for 10 seconds) of the obtained solid electrolytic capacitor.

Example 2
A capacitor element was produced in the same manner as in Example 1.

  Next, 60 mg of BIQ-TCNQ was packed in a bottomed cylindrical aluminum capacitor case (diameter 6 mmφ × height 7 mm), followed by 1-ethyl-3-methylimidazolium bis (trifluoromethane) which is a room temperature molten salt. Sulfone) imide (hereinafter abbreviated as “EMI-TFSI”, decomposition point: 417 ° C.) was added to 5% with respect to BIQ-TCNQ.

  Next, the capacitor case was placed on a hot plate having a temperature of 300 ° C., and the room temperature molten salt and the charge transfer complex salt mixture in the case were melted and liquefied.

  After the preheated capacitor element was immersed in the mixed melt, it was immediately cooled and solidified to form a cathode layer composed of a room temperature molten salt and a TCNQ complex salt.

  Next, the capacitor case was sealed with an epoxy resin, and aging was performed by applying a voltage of 4 V to both electrodes to complete a solid electrolytic capacitor.

  Table 1 shows the initial electrical characteristics, the capacity impregnation rate, and the electrical characteristics after high-temperature loading (held in an atmosphere at a temperature of 260 ° C. for 10 seconds) of the obtained solid electrolytic capacitor.

In Comparative Example 1, without impregnating the EMI-BF ₄ in the capacitor element, except that only the TCNQ complex salt is formed in the cathode layer, thereby completing a solid electrolytic capacitor in the same manner as in Example 1.

  Table 1 shows the initial electrical characteristics, the capacity impregnation rate, and the electrical characteristics after high-temperature loading (held in an atmosphere at a temperature of 260 ° C. for 10 seconds) of the obtained solid electrolytic capacitor.

  As shown in Table 1, the solid electrolytic capacitors (Examples 1 and 2) of the present invention in which the cathode layer composed of the room temperature molten salt and the TCNQ complex salt was formed by forming only the conventional TCNQ complex salt in the cathode layer. Compared with the solid electrolytic capacitor of the comparative example, it can be seen that the capacity impregnation rate is high and has excellent electrical characteristics. In addition, according to the solid electrolytic capacitor of the present invention, by using a room temperature molten salt excellent in heat resistance, the electric characteristics are not deteriorated after a high temperature load, and the capacitor is excellent in heat resistance and durability.

Claims (7)

A solid electrolytic capacitor, wherein a cathode layer made of a room temperature molten salt and a TCNQ complex salt is formed on an anode foil on which a dielectric oxide film is formed. The solid electrolytic capacitor according to claim 1, wherein the room temperature molten salt is a room temperature molten salt having a decomposition temperature of at least 300 ° C. The solid electrolytic capacitor according to claim 1, wherein the room temperature molten salt is 1-butylpyridinium salt and / or 1-ethyl-3-methylimidazolium salt. A capacitor element in which an anode foil formed with a dielectric oxide film and a counter cathode foil are wound through a separator is impregnated with a room temperature molten salt, and then immersed in a molten and liquefied TCNQ complex salt. Thereafter, the TCNQ complex salt is cooled and solidified to form a cathode layer composed of a room temperature molten salt and a TCNQ complex salt on the anode foil. A capacitor element in which an anode foil formed with a dielectric oxide film and a counter cathode foil are wound through a separator is immersed in a mixed melt of a room temperature molten salt and a TCNQ complex salt, and then mixed and melted. A method for producing a solid electrolytic capacitor, wherein the liquid is cooled and solidified to form a cathode layer composed of a room temperature molten salt and a TCNQ complex salt on the anode foil. The method for producing a solid electrolytic capacitor according to claim 4, wherein the room temperature molten salt is a room temperature molten salt having a decomposition temperature of at least 300 ° C. The solid-state electrolysis according to any one of claims 4 to 6, wherein the room temperature molten salt is one of 1-butylpyridinium salt and / or 1-ethyl-3-methylimidazolium salt. Capacitor manufacturing method.