JP2003168630A - Solid electrolytic capacitor and its manufacturing method, and conductive composite material and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce ESR of a completed capacitor by improving conductivity of materials comprising a cathode member, in a solid electrolytic capacitor where a capacitor element wound by anode foil and opposite cathode foil with an electrolytic oxidized film via a separator is impregnated with solid cathode member. <P>SOLUTION: A cathode member is formed of a conductive composite material where carbon nanotubes are dispersed in a base material made of TCNQ complex salt. First, the mixed powder of TCNQ complex salt powder and carbon nanotubes is heated by raising a temperature, to melt and liquefy the TCNQ complex salt in the mixed powder and make a mixed melted body where the carbon nanotubes are dispersed in the melted liquid of TCNQ complex salt. Immediately after a capacitor is dipped in the mixed melted body, the entire body is cooled to solidify the TCNQ complex salt, completing the cathode member. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a solid electrolytic capacitor in which a solid cathode member is impregnated into a capacitor element in which an anode foil having an electrolytic oxide film and an opposing cathode foil are wound with a separator interposed therebetween.

[0002]

2. Description of the Related Art As a solid electrolytic capacitor in which a solid cathode member is impregnated into a capacitor element in which an anode foil having an electrolytic oxide film and an opposing cathode foil are wound with a separator interposed therebetween, a structure as shown in FIG. Those who have are known.

In this solid electrolytic capacitor, a cathode member made of TCNQ complex salt is impregnated into a capacitor element 7 in which an anode foil having an electrolytic oxide film and a counter cathode foil are rolled up in a cylindrical shape with a separator interposed therebetween. The capacitor element is housed in a cylindrical outer case 8 with a bottom, and a sealing rubber 9 is attached and sealed. Reference numerals 51 and 52 denote lead wires drawn from the anode foil and the cathode foil.

Here, TCNQ means 7,7,8,8-tetracyanoquinodimethane, and as a CNQ complex salt suitable for the cathode member of a solid electrolytic capacitor, isoquinone in which the N-position is substituted with an alkyl group is used. Those composed of a cation, a TCNQ anion, and a neutral TCNQ are known.

As a method for manufacturing such a solid electrolytic capacitor, Japanese Patent Laid-Open No. 173928/1982 discloses that a TCNQ complex salt is melted and liquefied in a container which is an exterior member of the capacitor.
After immersing the capacitor element in the melt, TCN is used as it is.
A technique for cooling and solidifying a Q complex salt is disclosed, and Japanese Patent Application Laid-Open No. 8-330190 discloses a technique in which a capacitor element is immersed in a melted and liquefied TCNQ complex salt in a first container and then withdrawn to solidify and cool the TCNQ complex salt. A technique of storing in a second container serving as an exterior member is disclosed.

[0006]

In the solid electrolytic capacitor having the above structure, the TCNQ complex salt forming the cathode member has a conductivity of about 1 S / cm, but the ESR (equivalent series resistance) of the solid electrolytic capacitor is It is desired to further increase the conductivity of the material forming the cathode member.

[0007]

A solid electrolytic capacitor according to the present invention comprises a capacitor element in which an anode foil having an electrolytic oxide film and a counter cathode foil are wound around a separator,
A solid electrolytic capacitor impregnated with a solid cathode member is characterized in that the cathode member is made of a conductive composite material in which carbon nanotubes are dispersed in a base material made of a TCNQ complex salt.

Carbon nanotubes are conductive particles consisting of carbon atoms only, and have a diameter of 1-10 nm and a length of 10 nm.
It has a cylindrical shape of 0 to 1000 nm. The carbon nanotubes include a single-wall type and a multi-wall type, and in the present invention, either a single-layer type or a multi-layer type may be used.

In the conductive composite material constituting the cathode member, the carbon nanotubes dispersed in the TCNQ complex salt base material preferably have higher conductivity than the TCNQ complex salt base material. The cathode member made of such a composite material has a higher conductivity than that made of a conventional TCNQ complex salt base material alone, and brings about a reduction in ESR as a finished capacitor product.

Further, the method for producing a solid electrolytic capacitor according to the present invention is a solid electrolytic device in which a solid cathode member is impregnated into a capacitor element in which an anode foil having an electrolytic oxide film and a counter cathode foil are wound around a separator. In the method for manufacturing a capacitor, a mixed powder of TCNQ complex salt powder and carbon nanotubes is heated and heated to obtain TCNQ in the mixed powder.
By melting and liquefying a complex salt to prepare a mixed melt in which carbon nanotubes are dispersed in a melt of the TCNQ complex salt, and immersing the capacitor element in the mixed melt, and immediately cooling to solidify the TCNQ complex salt. By T
The present invention is characterized in that a cathode member made of a conductive composite material in which carbon nanotubes are dispersed in a base material made of a CNQ complex salt is formed.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A solid electrolytic capacitor corresponding to one embodiment of the present invention, referring to FIG. 1, is a cylinder of an anode aluminum foil having an electrolytic oxide film and a counter cathode aluminum foil with a separator interposed therebetween. The capacitor element 7 wound in a circular shape is impregnated with a cathode member made of a conductive composite material in which carbon nanotubes are dispersed in a base material made of TCNQ complex salt, and the capacitor element is placed in a bottomed cylindrical aluminum case 8. It is stored and sealed with a sealing rubber 9. Reference numerals 51 and 52 denote lead wires drawn from the anode foil and the cathode foil.

The cathode member having the above structure is
A mixed powder of CNQ complex salt powder and carbon nanotubes is loaded in a cylindrical aluminum case having a bottom, and the case is subjected to high frequency heating to melt and liquefy the TCNQ complex salt in the mixed powder to melt the TCNQ complex salt. A mixed melt in which carbon nanotubes are dispersed is prepared, and after immersing the capacitor element in the mixed melt, the capacitor element is not pulled out from the case or is pulled out from the case and cooled to solidify the TCNQ complex salt. Is formed by.

After the capacitor element is immersed in the mixed melt, the TCNQ is not pulled out from the case.
When the complex salt is cooled and solidified, the case can be used as an outer case as it is, and when the capacitor element is pulled out from the case and solidified by cooling, it can be stored in another outer case.

Regarding the conductive composite material constituting the cathode member layer, the TCNQ complex salt base material is 0.1 to 10 S.
A carbon nanotube having a conductivity of / cm can be used.
A material having a conductivity of 1000 S / cm can be used, but it is preferable to use carbon nanotubes having a higher conductivity than the TCNQ complex salt base material as a combination of both. The cathode member layer made of such a composite material has higher conductivity than a conventional one made of only a TCNQ complex salt base material, so that an ES finished capacitor product is obtained.
Results in a reduction of R.

If the amount of carbon nanotubes dispersed in the TCNQ complex salt base material is too small, the effect of improving the conductivity of the conductive composite material becomes small, and if too large, the conductive composite material becomes brittle. Microcracks and the like occur, and the conductivity decreases. The preferred carbon nanotube content in the conductive composite material is 5 to 50% by weight.
(More preferably 10 to 20% by weight).

Here, according to the embodiment of the present invention,
Example 1 in which the content of carbon nanotubes in the conductive composite material constituting the cathode member was 5% by weight, and 15% by weight
Example 2 and the solid electrolytic capacitor of Comparative Example 1 of 0% (not containing) were subjected to a reflow test (230 ° C.
Held in steam for 30 seconds) and measured before and after the test: capacitance: C, tangent of loss angle: tan δ, equivalent series resistance:
Table 1 shows the ESR values.

In Table 1, C and tan δ are 120H
z and ESR were measured at 100 kHz, and
C / C indicates the rate of change in capacitance.

[0018]

[Table 1]

As can be seen from Table 1, Examples 1 to 4
In Comparative Example 1, the change in capacitance due to the reflow test is smaller than in Comparative Example 1, and the ESR and tan δ are smaller both before and after the test of the reflow test.

[0020]

According to the present invention, in a solid electrolytic capacitor in which a solid cathode member is impregnated into a capacitor element in which an anode foil having an electrolytic oxide film and an opposing cathode foil are wound with a separator interposed therebetween, a cathode member The conductivity of the material that makes up the
R is reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a solid electrolytic capacitor.

[Explanation of symbols]

7 Capacitor element 8 exterior case 9 Seal rubber 51 Anode lead wire 52 Cathode lead wire

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hiroyuki Okuda             1-1 Sanyo-cho, Daito-shi, Osaka Sanyo Electronics Department             Product Co., Ltd. F-term (reference) 5G301 DA18 DA60

Claims (5)

[Claims] 1. A solid electrolytic capacitor in which a solid cathode member is impregnated into a capacitor element formed by winding an anode foil having an electrolytic oxide film and an opposing cathode foil with a separator interposed therebetween, wherein the cathode member is made of a TCNQ complex salt. A solid electrolytic capacitor comprising a conductive composite material in which carbon nanotubes are dispersed in a base material. 2. The carbon nanotube is the TC
The solid electrolytic capacitor according to claim 1, which has a higher conductivity than that of the NQ complex salt base material. 3. A method for producing a solid electrolytic capacitor, which comprises a solid electrolytic capacitor impregnated with a capacitor element in which an anode foil having an electrolytic oxide film formed thereon and a counter cathode foil are wound with a separator interposed therebetween, and a powder of TCNQ complex salt is used. The mixed powder with the carbon nanotubes is heated and heated to melt and liquefy the TCNQ complex salt in the mixed powder to prepare a mixed melt in which the carbon nanotubes are dispersed in the melt of the TCNQ complex salt. After the capacitor element is immersed in the melt, it is immediately cooled to solidify the TCNQ complex salt.
A method for producing a solid electrolytic capacitor, which comprises forming a cathode member made of a conductive composite material in which carbon nanotubes are dispersed in a base material made of a Q complex salt. 4. A conductive composite material, wherein carbon nanotubes are dispersed in a base material made of a TCNQ complex salt. 5. A method for producing a conductive composite material in which carbon nanotubes are dispersed in a base material made of TCNQ complex salt, wherein a mixed powder of powder of TCNQ complex salt and carbon nanotubes is heated and heated to obtain the mixed powder. By melting and liquefying the TCNQ complex salt in the body, a mixed melt in which carbon nanotubes are dispersed in the melt of the TCNQ complex salt is produced, and the mixed melt is immediately cooled to solidify the TCNQ complex salt to obtain the TCNQ complex salt. A method for producing a conductive composite material, which comprises dispersing carbon nanotubes in a base material made of.