JP2009295660A - Solid-state electrolytic capacitor and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state electrolytic capacitor which improves adhesiveness of a capacitive element, an anode lead terminal and a cathode lead terminal with outer coating resin in the chip type solid-state electrolytic capacitor, suppresses the occurrence of cracks in the outer coating resin, and achieves improvement in the reliability of the solid-state electrolytic capacitor. <P>SOLUTION: The solid-state electrolytic capacitor includes the capacitive element provided with an anode part and a cathode part, the anode lead terminal connected to the anode part, the cathode lead terminal connected to the cathode part, and the outer coating resin for coating the capacitive element. Each of the anode lead terminal and the cathode lead terminal has a portion exposed or projected from the outer coating resin and a portion coated with the outer coating resin, and boundary parts with the exposed or projected portions of the anode lead terminal and the cathode lead terminal out of the portions coated with the outer coating resin are brought into contact with the outer coating resin through an organic silane layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a solid electrolytic capacitor having a shape formed by coating a capacitor element, an anode lead terminal, and a cathode lead terminal with an exterior resin, and a method for manufacturing the same.

  Generally, a capacitor element used for a solid electrolytic capacitor is prepared by, for example, as described in Patent Document 1 and the like, a valve action metal powder such as tantalum is solidified into a substantially rectangular parallelepiped and sintered to produce an anode body. Forming a dielectric film having high insulation on the surface of the valve action metal powder in the anode body, and then forming a solid electrolyte layer such as manganese dioxide or a conductive polymer on the surface of the dielectric film, In this structure, a cathode lead layer is formed on the solid electrolyte layer.

The chip-type solid electrolytic capacitor includes, for example, an anode lead terminal and a cathode lead, in which the capacitor element having the structure described above is connected to the anode body of the capacitor element with an exterior resin, as described in Patent Document 1 and the like. Both of the cathode lead terminals connected to the layers are sealed as shown in FIG. 3 so as to protrude or be exposed outside the exterior resin.
JP 2004-344775 A.

  As described above, the chip-type solid electrolytic capacitor has a configuration in which the capacitor element is sealed with the exterior resin as described above, but moisture in the atmosphere has penetrated from the exterior resin to the capacitor element. .

  On the other hand, the capacitor element has a configuration in which a dielectric film formed on the surface of the valve action metal powder is covered with a solid electrolyte layer formed over the dielectric film. There is necessarily a portion that is not covered with the solid electrolyte layer.

  In addition, if the moisture infiltrated from the exterior resin comes into contact with the portion of the dielectric film that is not covered with the solid electrolyte layer, the leakage current characteristics may be deteriorated or dielectric breakdown may occur. There was a problem. Further, even if the initial leakage current characteristics are good, there is a problem that the leakage current deteriorates with time.

  In view of the above problems, the solid electrolytic capacitor of the present invention includes a capacitor element having an anode part and a cathode part, an anode lead terminal connected to the anode part, a cathode lead terminal connected to the cathode part, and the capacitor element And the anode lead terminal and the cathode lead terminal have a portion exposed or protruded from the exterior resin and a portion covered with the exterior resin, Of the portion of the anode lead terminal and the portion of the cathode lead terminal covered with the exterior resin, a boundary portion between the exposed or protruding portion is in contact with the exterior resin via an organosilane layer. .

  In the method for producing a solid electrolytic capacitor of the present invention, after the anode lead terminal and the cathode lead terminal are connected to the capacitor element, the capacitor element, the anode lead terminal, and the portion of the cathode lead terminal covered with the exterior resin Of these, the method includes a step of forming an organosilane layer on the peripheral surface of at least a boundary portion exposed to or protruding from the exterior resin.

  The organic silane layer may be formed using a silane coupling agent solution having a silane coupling agent concentration of 2.0 to 5.0 wt% in the solution.

  By making it the content of this invention, the adhesiveness of a capacitor | condenser element, an anode lead terminal, a cathode lead terminal, and exterior resin improves. By improving the adhesion between the anode lead terminal and the cathode lead terminal and the exterior resin in the vicinity of the boundary between the portion covered with the exterior resin of the anode lead terminal and the cathode lead terminal and the portion exposed or projected from the exterior resin, the external Intrusion of moisture into the exterior resin can be prevented, and generation of cracks in the exterior resin due to moisture that has entered from the outside can be suppressed. In addition, since the adhesion between the capacitor element and the exterior resin is improved, moisture existing in the resin can be prevented from entering the capacitor element. As a result, deterioration of the characteristics of the solid electrolytic capacitor can be prevented. Therefore, according to the present invention, the reliability of the solid electrolytic capacitor can be improved.

  The best mode for carrying out the present invention will be described below.

  FIG. 1 is a front sectional view of a solid electrolytic capacitor of the present invention. As shown in FIG. 1, the solid electrolytic capacitor of the present invention comprises a capacitor element 1, an anode lead terminal 2, a cathode lead terminal 3, and an exterior resin 4. The capacitor element 1, the anode lead terminal 2, and Portions 21 and 31 of the cathode lead terminal 3 that are covered with the exterior resin 4 are in contact with the exterior resin 4 through the organosilane layer 5. Here, in order to prevent moisture from entering the exterior resin 4 from the outside, the organic silane layer 5 has portions 21 and 31 covered with the exterior resin 4 of the anode lead terminal 2 and the cathode lead terminal 3. Of these, it is only necessary to be formed on the surface in the vicinity of the boundary portions 211 and 311 with the portions 22 and 32 exposed or protruded from the exterior resin 4, but the portion 21 covered with the exterior resin 4 as described above. , 31 and the capacitor element 1 are preferably formed on the surface. In this case, the adhesion between the capacitor element 1, the anode lead terminal 2, the cathode lead terminal 3 and the exterior resin 4 is improved, so that moisture in the exterior resin 4 can be prevented from adhering to the capacitor element 1. Degradation of the characteristics of the solid electrolytic capacitor can be prevented.

  The capacitor element 1 has a structure shown in FIG. 2, for example. That is, it has an anode body 11 made of a valve metal such as tantalum having an anode lead 10 planted, and a dielectric coating 12, a solid electrolyte layer 13, and a cathode lead layer 14 are sequentially formed on the peripheral surface of the anode body 11. ing. Here, the shape of the capacitor element 1 is not limited to the shape shown in FIG. 2. For example, a foil made of a valve metal may be used as the anode body 11.

  The organic silane layer 5 is formed of a silane coupling agent, and has an effect of improving adhesion between the capacitor element 1, the anode lead terminal 2, the cathode lead terminal 3, and the exterior resin 4. The adhesion of the exterior resin 4 with the vicinity of the boundary between the portion exposed or protruding from the exterior resin 4 and the portion covered with the exterior resin 4 in the anode lead terminal 2 and the cathode lead terminal 3 is improved. Thus, moisture can be prevented from entering the interior of the exterior resin 4, and cracking of the exterior resin 4 due to moisture entering from the outside can be suppressed. Further, by improving the adhesion between the capacitor element 1 and the exterior resin 4, it is possible to prevent moisture from entering the capacitor element 1 from the exterior resin 4, and to suppress deterioration of the characteristics of the solid electrolytic capacitor. .

  Next, the manufacturing method of this invention is demonstrated.

  First, in the present invention, a conventionally known method can be used as a method of forming the capacitor element 1. For example, the anode lead 10 is disposed so as to protrude, and the anode body 11 is produced by pressure-molding and sintering powder made of a valve metal using a mold or the like. Next, the dielectric solution 12 is formed on the peripheral surface of the anode body 11 by preparing an acid solution and immersing the anode body 11 in the acid solution. Thereafter, a solid electrolyte comprising an inorganic semiconductor layer such as manganese dioxide, an organic semiconductor layer such as TCNQ (7,7,8,8-tetracyanoquinodimethane) complex salt, and a conductive polymer layer such as polypyrrole, polythiophene, and polyaniline. Layer 13 is formed by known techniques. A cathode lead layer 14 is formed on the surface of the solid electrolyte layer 13 to produce the capacitor element 1. The solid electrolyte layer 13 and the cathode lead layer 14 may be composed of a single layer or a plurality of layers. Moreover, when it is set as a some layer, the layer which consists of the same material may be laminated | stacked, but each layer may be formed from a different material. Hereinafter, the anode lead 10 is referred to as an anode portion 1a, and the solid electrolyte layer 13 and the cathode layer 14 are referred to as a cathode portion 1b.

  The capacitor element 1 manufactured as described above is placed on and connected to the anode lead terminal 2 and the cathode lead terminal 3 formed in a predetermined shape in advance by punching or the like. At this time, the anode portion 1a is placed on the anode lead terminal 2 and the cathode portion 1b is placed on the cathode lead terminal 3, so that the anode lead terminal 2 and the cathode portion 1b are not in contact with each other. The connection method can be appropriately selected from known techniques such as resistance welding, laser welding, or a method using a conductive adhesive.

  Next, a silane coupling agent solution is prepared. As silane coupling agents, γ-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, p -Styryltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) 3-aminopropyltrimethoxysilane, N- Any of conventionally known materials such as phenyl-3-aminopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane can be used without particular limitation. The solvent used in the silane coupling agent solution is not particularly limited as long as it can dissolve or disperse the silane coupling agent. For example, alcohols such as water, methanol, ethanol, isopropyl alcohol, and butanol , Ketones such as acetone, methyl ethyl ketone, ethyl isobutyl ketone, methyl isobutyl ketone, ethylene glycols such as ethylene glycol, ethylene glycol methyl ether, ethylene glycol mono-n-propyl ether, propylene glycol, propylene glycol methyl ether, propylene glycol ethyl Propylene glycols such as ether, propylene glycol butyl ether, propylene glycol propyl ether, dimethylformamide, dimethylacetoa Amides such as pyrrolidone, pyrrolidones such as N-methylpyrrolidone and N-ethylpyrrolidone, dimethylsulfoxide, γ-butyrolactone, methyl lactate, ethyl lactate, methyl β-methoxyisobutyrate, methyl α-hydroxyisobutyrate, etc. Anilines such as aniline and N-methylaniline can be used.

  The concentration of the silane coupling agent in the silane coupling agent solution is preferably 2.0 to 5.0 wt%. The silane coupling agent has an effect of strengthening the connection between the cathode portion 1b made of an inorganic material, the anode portion 1a made of an inorganic material, the anode lead terminal 2, the cathode lead terminal 3, and the exterior resin 4 which is an organic layer described later. However, if the concentration of the silane coupling agent is less than 2.0 wt%, the effect of improving the adhesion between the inorganic substance and the organic substance will be insufficient. Moreover, although a silane coupling agent is combined with an inorganic substance by a hydrolysis reaction, when the concentration of the silane coupling agent is greater than 5.0 wt%, the hydrolysis reaction is difficult to occur and the surface is made of an inorganic material such as the cathode portion 1b. As a result, the adhesion between the anode portion 1a, the anode lead terminal 2, the cathode lead terminal 3 and the organosilane layer 5 is insufficient, and as a result, the capacitor element 1, the anode lead terminal 2, the cathode lead terminal 3 and the exterior resin 4 The effect of improving the adhesion is not sufficient.

The silane coupling agent solution prepared with the above materials and proportions is attached to the surface of the capacitor element 1 and the surfaces of the portions 21 and 31 covered with the exterior resin 4 of the anode lead terminal 2 and the cathode lead terminal 3. . As a method for attaching the silane coupling agent solution, a method of immersing the capacitor element 1 in which the anode lead terminal 2 and the cathode lead terminal 3 are connected to the silane coupling agent solution, an anode lead terminal 2, a cathode lead terminal 3, There is a method of applying the silane coupling agent solution to the capacitor element 1. Thereafter, the organic silane layer 5 is formed by drying the silane coupling agent solution.
The organosilane layer 5 may be formed over the entire surface of the anode lead terminal 2 and the cathode lead terminal 3, but the portions 21 and 31 of the anode lead terminal 2 and the cathode lead terminal 3 that are covered with the exterior resin 4. Among these, at least the boundary portions 211 and 311 with the portions 22 and 32 exposed or protruded from the exterior resin 4 may be formed. When the organosilane layer 5 is formed at the above-described locations 211 and 311, it is possible to prevent moisture from entering the exterior resin 4 from the outside. As a method of forming the organic silane layer 5, the anode lead terminal 2 and the cathode lead terminal are applied to the silane coupling agent solution in which the portions exposed from the exterior resin 4 of the anode lead terminal 2 and the cathode lead terminal 3 are covered with a masking tape or the like. 3 and the capacitor | condenser element 1 can be immersed, and the method of apply | coating the said silane coupling agent solution to these can be considered. Moreover, as a drying method, the method of leaving for a long time at room temperature, the method of heating, those combinations, etc. can be considered and it does not specifically limit.

  Next, the capacitor element 1 is covered with the exterior resin 4 so that parts of the anode lead terminal 2 and the cathode lead terminal 3 protrude. As such a method, for example, there is a method of covering the capacitor element 1 with a mold and injecting the exterior resin 4 into the mold.

  After the exterior resin 4 is formed, the anode lead terminal 2 and the cathode lead terminal 3 protruding from the exterior resin 4 are arranged so that the tips of the anode lead terminal 2 and the cathode lead terminal 3 are on the same plane along the exterior resin 4. 1 to produce the solid electrolytic capacitor shown in FIG.

(Example 1)
The anode lead was protruded, the valve action metal powder was pressure molded, and sintered to prepare an anode body. Next, the anode body was immersed in an acid solution to form a dielectric film on the peripheral surface of the anode body, and then a solid electrolyte layer composed of a conductive polymer layer was formed by a conventionally known method. Thereafter, a cathode lead layer composed of a conductive carbon layer and a silver paste layer was formed to produce a capacitor element. Next, the capacitor element is placed on the anode lead terminal and the cathode lead terminal formed in a predetermined shape, and the anode lead terminal and the anode lead of the capacitor element, and the cathode lead terminal and the cathode lead portion of the capacitor element are respectively connected. .

  Prepare a silane coupling agent solution using 0.2 g of γ-glycidoxypropylsilane as a silane coupling agent and 99.8 g of n-butanol as a solvent, and use an exterior resin for the anode lead terminal and the cathode lead terminal. The part to be coated and the capacitor element were immersed in the silane coupling agent solution. Then, after standing at room temperature for 10 minutes to 1 hour, drying was performed at 80 ° C. to 150 ° C. for 5 to 30 minutes.

After forming an organosilane layer on the surface of the capacitor element, anode lead terminal, and cathode lead terminal as described above, the capacitor element and a part of the anode lead terminal and cathode lead terminal are covered with an exterior resin, and the exterior A solid electrolytic capacitor was manufactured by bending the anode lead terminal and the cathode lead terminal protruding from the resin along the exterior resin so that the tips were on the same plane.
(Example 2)
A solid was obtained in the same manner as in Example 1 except that 0.5 g of γ-glycidoxypropyltriethoxysilane was used as a silane coupling agent and 99.5 g of n-butanol was used as a solvent to prepare a silane coupling agent solution. An electrolytic capacitor was produced.
(Example 3)
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that 2 g of 3-aminopropyltrimethoxysilane was used as a silane coupling agent and 98 g of n-butanol was used as a solvent, to prepare a silane coupling agent solution.
(Example 4)
A solid electrolytic capacitor was prepared in the same manner as in Example 1 except that 5 g of 3-chloropropyltrimethoxysilane was used as a silane coupling agent and 95 g of n-butanol was used as a solvent, to prepare a silane coupling agent solution.
(Example 5)
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that 10 g of vinyltrimethoxysilane was used as a silane coupling agent and 90 g of n-butanol was used as a solvent, to prepare a silane coupling agent solution.
(Example 6)
A solid electrolytic capacitor was produced in the same manner as in Example 1 except that 20 g of 3-methacryloxypropyltrimethoxysilane was used as the silane coupling agent and 80 g of n-butanol was used as the solvent to produce a silane coupling agent solution. .
(Comparative Example 1)
After connecting the capacitor element, the anode lead terminal, and the cathode lead terminal, a solid electrolytic capacitor was fabricated in the same manner as in Example 1 except that the organosilane layer was not formed.

  150 solid electrolytic capacitors of Examples 1 to 6 and Comparative Example 1 were prepared, and the ratio of occurrence of cracks in the exterior resin when reflowing after moisture absorption was determined. The results are shown in Table 1. In order to improve reliability, moisture absorption conditions and reflow conditions were made stricter than the product usage range. Specifically, the moisture absorption condition was exposed to 85 ° C. and 85% humidity for 48 hours, and the reflow condition was set to a peak temperature of 260 ° C.

  From Table 1, the embodiment of the present invention in which the organosilane layer was formed on the surfaces of the capacitor element, the anode lead terminal, and the cathode lead terminal had a reduced crack generation rate compared to the conventional example in which the organosilane layer was not formed. It can be seen that there is an effect of improving reliability. In addition, when the concentration of the silane coupling agent solution used to form the organic silane layer is 2.0 to 5.0 wt%, since the crack generation rate is particularly reduced, the organic silane layer is used at this ratio. It can be seen that it is preferable to form These reductions in the crack generation rate are due to the organic silane layer functioning as a coupling, and the connection between the cathode lead layer, anode lead terminal and cathode lead terminal of the capacitor element, which is an inorganic layer, and the exterior resin, which is an organic layer. Therefore, it is possible to prevent moisture from entering the exterior resin and the capacitor element. Thus, it is considered that the generation of cracks in the exterior resin due to the moisture could be suppressed.

Moreover, about the solid electrolytic capacitor of Examples 1-6 and the comparative example 1, although the time-dependent change of the leakage current was investigated, compared with the comparative example 1, the amount of temporal change of Examples 1-6 is small, and it is excellent in reliability. I found out.
The above embodiments and examples are only for explaining the present invention, and should not be construed as limiting the invention described in the claims. The present invention can be freely modified within the scope of the claims and the scope of equivalent meanings. For example, the solid electrolytic capacitor of the present invention shown in FIG. 1 includes only a single capacitor element. However, in the present invention, a plurality of capacitor elements may be included. In addition, the shape of the solid electrolytic capacitor of the present invention is not limited to that shown in FIG. 1. For example, the anode lead terminal and the cathode lead terminal do not protrude from the exterior resin and are exposed from one side surface of the exterior resin. It doesn't matter.

It is front sectional drawing of the solid electrolytic capacitor of this invention. It is front sectional drawing of the capacitor | condenser element of this invention. It is front sectional drawing of the conventional solid electrolytic capacitor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Capacitor element 2 Anode lead terminal 3 Cathode lead terminal 4 Exterior resin 5 Organosilane layer

Claims (4)

In a solid electrolytic capacitor comprising a capacitor element comprising an anode part and a cathode part, an anode lead terminal connected to the anode part, a cathode lead terminal connected to the cathode part, and an exterior resin covering the capacitor element ,
The anode lead terminal and the cathode lead terminal have a portion exposed or projected from the exterior resin, and a portion covered with the exterior resin,
Of the portions of the anode lead terminal and the cathode lead terminal that are covered with the exterior resin, at least a boundary portion between the exposed or protruding portion is in contact with the exterior resin through an organosilane layer. A solid electrolytic capacitor. Solid electrolysis comprising a capacitor element having an anode part and a cathode part, an anode lead terminal connected to the anode part, a cathode lead terminal connected to the cathode part, and an exterior resin covering the capacitor element In the method of manufacturing a capacitor,
After the capacitor element is connected to the anode lead terminal and the cathode lead terminal, the organosilane layer is formed on the surface of the capacitor element, the anode lead terminal, and the cathode lead terminal covered with the exterior resin. The manufacturing method of the solid electrolytic capacitor characterized by having the process to do. In the manufacturing method of the solid electrolytic capacitor of Claim 1,
The organic silane layer attaches the silane coupling agent solution to at least the surface of the boundary between the anode lead terminal and the cathode lead terminal covered with the exterior resin and the exposed or protruding part. Formed by
The said silane coupling agent solution has 2.0-5.0 wt% silane coupling agent, The manufacturing method of the solid electrolytic capacitor characterized by the above-mentioned. The organosilane layer is formed by attaching a silane coupling agent solution to at least a portion of the anode lead terminal and the cathode lead terminal that is covered with the exterior resin and the surface of the capacitor element,
The method for producing a solid electrolytic capacitor according to claim 2, wherein the silane coupling agent solution contains 2.0 to 5.0 wt% of a silane coupling agent.

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