JP3080851B2 - Method for manufacturing solid electrolytic capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a solid electrolytic capacitor using a powdered metal or an etched foil of a valve metal such as tantalum or niobium.
The present invention relates to a method for manufacturing a solid electrolytic capacitor using a conductive polymer compound as a solid electrolyte layer.

[0002]

2. Description of the Related Art A solid electrolytic capacitor using a valve action metal basically has a valve action metal 1 as an anode side electrode as shown in a partially enlarged sectional view encircled by a circle in FIG. The metal oxide film 2 obtained by oxidizing the valve metal on the anode side is used as a dielectric, and the solid electrolyte 3 formed on the metal oxide film 2 and the conductor layer 4 thereon are used as a cathode electrode. As the valve metal, tantalum, niobium, and the like are well known, and an anodic oxidation method is usually used for forming the metal oxide film. In addition, a multilayer structure film in which a graphite layer 5 and a silver paste layer 6 are stacked is often used for the conductor layer 4 which forms a part of the cathode-side electrode. The solid electrolytic capacitor having such a structure is generally manufactured through the following steps. FIG. 6 shows an example of a manufacturing process using a capacitor using tantalum.
This will be described with reference to (a) to (d). Process Tantalum powder is formed into a columnar or square pillar shape. The same tantalum wire rod 8 is planted on one bottom surface of this molded body. The tantalum wire 8 serves as an internal lead for electrical connection inside the capacitor, and is also used as a lead terminal in an anodizing step (described later) for forming a tantalum oxide film (Ta ₂ O ₅ ). Become. This tantalum wire 8 is hereinafter referred to as an anode lead. Step The above-mentioned powder compact with an anode lead is sintered to obtain a tantalum sintered compact pellet (hereinafter referred to as a pellet) 9 having a very large surface area (FIG. 6A). Step The pellets 9 are immersed in an acidic solution such as a nitric acid solution and anodized by applying a voltage to form a tantalum oxide film 2 on the surface of the metal tantalum 1. At this time, in order to improve work efficiency, as shown in FIG. 6 (b), a number of pellets 9 are attached to one strip-shaped metal support member 10, and the plurality of pellets 9 are immersed in one solution tank to apply a voltage. And apply
Perform anodic oxidation all at once. Attachment of the pellets 9 to the support material 10 is performed by connecting the anode lead 8 of each pellet to the support material 1 described above.
This is done by welding to zero. Subsequent steps are performed in units of the support material 10. Step After the anodization is completed, a solid electrolyte layer 3 is formed on the tantalum oxide film 2.

Conventionally, pyrolytic manganese dioxide, such as that obtained by thermal decomposition of manganese nitrate, has been widely used as a solid electrolyte. Attention has been paid to the relaxation of heat history during the process. The present invention provides such
The present invention relates to a capacitor using a conductive polymer compound as a solid electrolyte.

The formation of the conductive polymer compound layer 3 is usually performed by
This is performed as follows. The pellet on which the tantalum oxide film has been formed is immersed in a reaction solution containing a monomer of a conductive polymer compound for a certain period of time to fill the inside of the porous sintered body with the monomer. Then, it is immersed in a reaction solution containing an oxidizing agent for a certain period of time, and is oxidatively polymerized at −50 ° C. to around room temperature. A series of these operations, ie, charging of a monomer, contact with an oxidizing agent, and oxidative polymerization are repeated several times to form a conductive polymer compound layer.
The order in which the pellets are immersed in the reaction solution may be such that the oxidizing agent is preceded by immersion in the monomer. Next, a graphite layer 5 and a silver paste layer 6 are sequentially formed on the solid electrolyte 3 to form a cathode conductor layer 4. Step Further, the anode lead 8 welded to the support member 10 in the above-described step is cut to separate the support member 10 and the pellet 9 (FIG. 6C). The cutting position is set in the middle of the anode lead 8 so that the anode lead 8 remains on the pellet 9. This state is hereinafter referred to as a capacitor element. An external anode lead terminal and an external cathode lead terminal serving as terminals for electrical connection to the outside are attached to the capacitor element 11 separated from the process. In this case, the attachment of the external anode lead terminal is performed as follows. That is,
As shown in FIG. 6 (d), a metal anode terminal member 13 having a shape in which a number of metal pieces 12 to be used as external anode lead terminals protrude in a comb-like shape from a band-like portion is prepared.
Is welded to the anode lead 8 of the capacitor element. On the other hand, the attachment of the external cathode lead terminal is similarly performed by using a metal cathode terminal member 15 having a shape in which a metal piece 14 to be an external cathode lead terminal protrudes in a comb-like shape from a strip-shaped portion. This is performed by bonding the conductive element 16 to the cathode conductor layer 4 of the capacitor element. A resin exterior is applied to the capacitor element by process transfer molding or the like, and this is sealed (not shown). From the strip portions of the anode terminal member 13 and the cathode terminal member 15, the external anode lead terminal 12 and the external cathode lead terminal
4 are cut off, and the respective external lead terminals 12, 1
4 is bent along the exterior resin to perform lead molding (not shown) to complete the capacitor.

[0005] The above description of the manufacturing process is based on the manufacturing process of a solid electrolytic capacitor using manganese dioxide, and the process that can be applied to a capacitor using a conductive polymer compound is described. In the case of a capacitor using a polymer compound, the external anode lead terminal 1 used in the process is replaced with a simple support member 10 (see FIG. 6B) in the process.
The anode terminal member 13 is shown in FIG.
(D), the anode lead cutting work in the process (FIG. 6C) and the anode lead re-welding work in the process (FIG. 6D) can be reduced. As a result, not only the manufacturing cost can be reduced, but also the damage of the tantalum oxide film due to the stress caused by the cutting and welding operations can be prevented, and the reliability of the capacitor can be improved.

In the case of a capacitor using manganese dioxide, as described above, the welded portion between the external anode lead terminal 12 and the anode lead 8 is oxidized and deteriorated by the heat and the gas generated during the thermal decomposition of manganese nitrate. Therefore, the part welded prior to the thermal decomposition of manganese nitrate in the process cannot be used as an external anode lead terminal as it is, but when using a conductive polymer compound as a solid electrolyte, This is because the pellet is not exposed to a high temperature during its formation and can be used as it is as an external anode lead terminal.

As described above, solid electrolytic capacitors include those using manganese dioxide as a solid electrolyte and those using a conductive polymer compound. In any case, these solid electrolytes are, of course, to be formed only on the tantalum oxide film, and must not come into contact with the metal on the anode side, that is, the exposed metal surface of the tantalum sintered body or the anode lead. . However, in the case of capacitors using pyrolytic manganese dioxide, conventionally, when forming manganese dioxide, the phenomenon of so-called `` creeping of semiconductor mother liquor to the anode lead '' occurs, and sometimes the anode lead comes into contact with manganese dioxide to form a capacitor. It is well known that the leakage current becomes large, and in severe cases, an accident occurs in which the capacitor characteristics are lost.

As a method for preventing the contact between the anode lead and manganese dioxide as described above, conventionally, prior to the manganese dioxide forming step of the above-mentioned step, the root portion of the anode lead (the anode lead implantation surface of the sintered body is removed). (Including a water-repellent resin layer). Techniques for preventing crawling using such a water-repellent resin are disclosed in, for example, Japanese Patent Publication No. 144008, Japanese Patent Publication No. 41244, Japanese Patent Laid-Open No. 58-154224, and Japanese Patent Laid-Open No. 59-135716. In this case, as a water-repellent resin, a fluorine-based resin having high heat resistance, such as ethylene tetrafluoride, which does not decompose even at the thermal decomposition temperature of manganese nitrate is used.

On the other hand, in the field of capacitors using a conductive polymer compound as a solid electrolyte, conventionally,
Report on the phenomenon of polymer compound creeping up to anode lead
No capacitor has been found, and no capacitor has been known to prevent such crawling.

[0010]

The inventor of the present invention has found that even in a capacitor using a conductive polymer compound, the reaction liquid creeps up on the anode lead in the same manner as when manganese dioxide is formed. Therefore, we selected ethylene tetrafluoride from the fluorine-based high heat-resistant resin used to prevent creeping in capacitors using manganese dioxide, and applied it to capacitors using conductive polymer compounds. Liquid crawling could not be completely prevented. This was due to the fact that the wettability of the reaction solution for forming a polymer compound layer was better than that of manganese nitrate which was a semiconductor mother liquor for forming manganese dioxide.

On the other hand, water-repellent resins include, in addition to the above-mentioned fluorine-based resins, thermosetting silicones such as those described in JP-A-62-2518 and JP-A-3-105906. Resins are known. According to the former publication, this resin protects a weld between an anode lead and an external anode lead terminal in a solid electrolytic capacitor using manganese dioxide from corrosive gas generated in a thermal decomposition process of manganese nitrate. On the other hand, in the latter gazette, in the dip type ceramic capacitor, the purpose is to prevent the occurrence of "powder resin dripping" at the lead terminal root portion, and for different purposes. However, it was thought that it could be applied to "prevention of liquid crawling to the anode lead". Therefore, using a commercially available thermosetting silicone resin, a water-repellent member layer was formed on the anode lead and on the lead implant surface prior to the formation of the conductive polymer compound layer. As a result, it was confirmed that the water repellency of the silicone resin was good, but a predetermined capacity value was not obtained, and the rate of appearance of the capacity was reduced. This is because the viscosity of the silicone resin formed on the anode lead placement surface is reduced by heating for curing the resin, and the resin permeates into the porous sintered body from the lead placement surface side. This is probably because the silicone resin film was formed on the tantalum oxide film near the surface of the sintered body on the surface side, and the oxide film in that portion did not contribute as a dielectric layer.

Accordingly, the present invention relates to a method for manufacturing a solid electrolytic capacitor using a conductive polymer compound as a solid electrolyte, and a method for preventing a reaction solution from crawling on an anode lead when a polymer compound layer is formed. And a capacitor with low leakage current can be manufactured.

Another object of the present invention is to provide a method for preventing the above-mentioned crawling, which does not lower the capacity appearance rate.

Further, the present invention takes advantage of the fact that the conductive polymer compound can be formed at a low temperature of room temperature or lower, and even when the external anode lead terminal and the anode lead are welded prior to the formation of the dielectric oxide film. It is an object of the present invention to reduce the number of manufacturing steps and reduce damage to a dielectric oxide film by preventing oxidation of a metal portion and deterioration of a welded portion.

[0015]

SUMMARY OF THE INVENTION A method of manufacturing a solid electrolytic capacitor according to the present invention is directed to a widened anode body in which a valve action metal wire is planted as an anode lead on a powdered compact or foil of a valve action metal. Forming an oxide film serving as a dielectric layer on the surface of the anode body; and forming a solid electrolyte layer made of a conductive polymer compound on the dielectric oxide film. In the method of manufacturing a capacitor, in order to prevent the conductive polymer compound layer from climbing up to the anode lead, prior to the formation of the solid electrolyte layer, the anode lead planting surface of the anode body and the anode lead A step of arranging a crawling prevention material made of a water-repellent resin at the planting root portion is provided.

An ultraviolet-curable silicone resin is used as the water-repellent resin for the crawling prevention material.

The order of the manufacturing steps is as follows: the anode body forming step, the crawling prevention material disposing step, the oxide film forming step, the solid electrolyte layer forming step, or the anode body forming step, the oxidation It is characterized in that a film forming step, the crawling prevention material disposing step, and the solid electrolyte layer forming step are performed in this order.

Before the formation of the crawling-up preventing material after the formation of the anode body, or prior to the formation of the oxide film after the formation of the anode body, the anode lead is electrically connected to the outside. A step of welding to a metal member including a portion to be an external anode lead terminal.

[0019]

In a capacitor using a conductive polymer compound as a solid electrolyte to which the present invention is applied, unlike a capacitor using pyrolytic manganese dioxide, a polymer compound layer is formed at a low temperature of room temperature or lower. Will be Therefore, when selecting a water-repellent resin, it is not necessary to particularly consider the decomposition temperature, and a silicone resin having a higher water-repellency than a highly heat-resistant fluororesin such as ethylene tetrafluoride can be used.

In the present invention, among the silicone resins, an ultraviolet-curable silicone resin is used. Unlike the thermosetting silicone resin, the ultraviolet curing silicone resin does not require heating for curing. Therefore, there is no decrease in the viscosity of the resin due to the heating, no penetration into the porous sintered body, and no decrease in the capacity in the vicinity of the lead implant surface, and the capacity appearance rate is high.

The formation temperature of the conductive polymer compound layer is low,
In addition, since the heat load due to ultraviolet irradiation required for curing the water-repellent silicone resin is small, the capacitor element does not substantially receive a heat history at room temperature or higher. Therefore, even if welding of the anode lead and the external anode lead terminal is performed prior to the anodic oxidation for forming the dielectric oxide film, oxidation of the metal portion and deterioration of the welded portion do not occur, and the external anode lead terminal is not changed. Can be used as Therefore, according to the manufacturing method of the present invention, since the cutting and re-welding of the anode lead can be omitted, the number of manufacturing steps can be reduced and the dielectric oxide film can be prevented from being damaged.

[0022]

Next, a preferred embodiment of the present invention will be described with reference to FIGS.
Will be described in comparison with a conventional manufacturing method. FIG.
FIG. 2 is a flowchart showing an example of the order of the manufacturing steps in the manufacturing method of the present invention, and FIG. 2 is a diagram showing the appearance of the capacitor according to the embodiment of the present invention in the order of the manufacturing steps. FIG. 3 is a flowchart showing another example of the order of the manufacturing steps in the manufacturing method of the present invention, and FIG. 4 is a flowchart showing another example of the order of the manufacturing steps. FIG. 5 is a diagram showing the appearance of a capacitor according to another embodiment of the present invention in the order of manufacturing steps.

Example 1 The capacitor of Example 1 was manufactured according to the manufacturing process flow shown in FIG. The appearance of the capacitor is shown in FIG.

First, a fine powder of tantalum is formed,
A cylindrical tantalum fine powder compact having a diameter of 1 mm and a diameter of 1 mm was prepared. On one surface of the molded body, a tantalum wire 8 having a diameter of 0.2 mm was implanted as an anode lead during powder molding. The compact with the tantalum wire was sintered to produce a sintered pellet 9 (step S1, FIG. 1A). CV value of pellet (capacitance value μF per 1 g and anodic oxidation voltage V
Is 23,000 / g.

Next, the tip of the anode lead 8 of the pellet 9 was welded to an iron strip-shaped support member 10 (step S in FIG. 1).
2, FIG. 2 (b)).

Next, an ultraviolet curable silicone resin is applied to the anode lead planting surface of the pellet 9 and the root of the anode lead 8, and then irradiated with light having a main wavelength of 365 nm at room temperature to cure the silicone resin ( In FIG. 1 step S3), a silicone resin layer 17 was formed (FIG. 2C).

The above-mentioned pellet 9 with a silicone resin layer
Was anodized to form a tantalum oxide film (Step S4 in FIG. 1). Anodization was performed in a 0.1% by weight aqueous nitric acid solution by applying a voltage of 60V.

Thereafter, a conductive polymer compound layer was formed on the tantalum oxide film (Step S5 in FIG. 1). The conductive polymer compound was polypyrrole and was formed by the following method. The pellet was immersed in a methanol solution of 20% by weight of iron nitrate for 1 minute at room temperature, immersed in a methanol solution of 50% by weight of a pyrrole monomer for 1 minute at room temperature, and then immersed in air for 30 minutes.
Hold for minutes to allow chemical oxidative polymerization. The charging of the oxidizing agent, the contact with the pyrrole monomer, and the polymerization, which were a series of these operations, were repeated 10 times to form black polypyrrole on the tantalum oxide film.

Further, a graphite layer and a silver paste layer were sequentially formed on the polypyrrole layer to form a cathode conductor layer (Step S6 in FIG. 1).

Next, the anode lead 8 is placed 1 m from the planting surface.
Then, the capacitor element 11 was cut off from the supporting member 10 at the position of m (step S7 in FIG. 1, FIG. 2D).

The separated capacitor element 11 is attached to the anode terminal member 13 and the cathode terminal member 15 for batch processing in the next step (step S8 in FIG. 1; FIG. 2).
(E)). In this case, on the anode side, the comb-shaped metal piece 12 of the anode terminal member 13 and the anode lead 8 of the element 11 were welded. On the other hand, on the cathode side, the cathode conductor layer 4 of the element 11 and the comb-shaped metal piece 14 of the cathode terminal member 15 are electrically conductive adhesive 16
Connected with. Terminal members 13 and 15 for anode and cathode respectively
The metal pieces 12 and 14 provided in the above are portions that will later become an external anode lead terminal and an external cathode lead terminal, respectively.

Thereafter, a resin sheath was formed by transfer molding (step S9 in FIG. 1). Thereafter, the external anode lead terminal 12 and the external cathode lead terminal 14 were separated from the respective belt-shaped support portions, and lead molding was performed to complete the tantalum solid electrolytic capacitor of the present example.

Table 1 shows the leakage current defect rate and the capacitance appearance rate of the completed capacitor.

Example 2 The capacitor of Example 2 was manufactured according to the manufacturing process flow shown in FIG. FIG. 2 shows the appearance of the capacitor in the order of the manufacturing process.

The same pellets 9 as in Example 1 were used and attached to an iron support 10 in the same manner as in Example 1 (Steps S1 and S2 in FIG. 3, FIGS. 2A and 2B).

Next, anodization was performed (step S in FIG. 3).
4). The anodic oxidation method and conditions are the same as in Example 1.

An ultraviolet-curing silicone resin was applied to the anode lead-planted surface and the base of the anode lead of the pellet 9 on which the tantalum oxide film had been formed, and the main wavelength was 365 at room temperature.
2 nm, the silicone resin is cured (step S3 in FIG. 3) to form a silicone resin layer 17 (FIG. 2).
(C)).

Thereafter, in the same manner as in Example 1, a polypyrrole layer as a conductive polymer compound layer, a graphite layer as a cathode conductor layer, and a silver paste layer were formed (FIG. 3).
Steps S5 to S6), the anode lead 8 was cut off from the support member 10 (step S7 in FIG. 3, FIG. 2D). Thereafter, the anode lead 8 and the external anode lead terminal 12 of the anode terminal member 13 are welded, and the cathode conductor layer 4 and the external cathode lead terminal 14 of the cathode terminal member 15 are bonded with a conductive adhesive 16 (FIG. 2 (e)), a resin exterior was applied, and lead molding was performed to complete the tantalum solid electrolytic capacitor of this example.

This embodiment is different from the first embodiment in that a silicone resin layer 17 for preventing crawling (FIG. 2C)
Is a point before (Example 1) or after (Example 2) the tantalum oxide film forming step. Table 1 shows the leakage current defect rate and the capacitance appearance rate of the capacitor of Example 2.

Example 3 The capacitor of Example 3 was manufactured according to the manufacturing process flow shown in FIG. FIG. 5 shows the appearance of the capacitor in the order of the manufacturing process.

Using the same pellets 9 as in Example 1 (FIG. 4, step S1, FIG. 5 (a)), the anode lead 8 was welded to the comb tooth-shaped metal piece 12 of the anode terminal member 13 (FIG. 4, step S20). 5 (b)). This anode terminal member 13
The one used in step S8 of the first embodiment (see FIG. 1);
The structures such as the material, the outer shape, and the dimensions are the same, and the tooth-shaped metal piece 12 of the comb is a portion to be an external anode lead terminal later.

Next, an ultraviolet curable silicone resin is applied to the anode lead planting surface and the anode lead base of the pellet 9 and irradiated with light having a main wavelength of 365 nm at room temperature to be cured (step S3 in FIG. 4). Then, a silicone resin layer 17 was formed (FIG. 5C).

Thereafter, in the same manner as in Example 1, a tantalum oxide film, a polypyrrole layer, a graphite layer, and a silver paste layer were sequentially formed (Steps S4 to S6 in FIG. 4).

Next, the cathode conductor layer 4 and the external cathode lead terminal 14 of the cathode terminal member 15 were bonded with a conductive adhesive 16 (Step S80 in FIG. 4, FIG. 5D).

Further, in the same manner as in Example 1, the capacitor element was coated with a resin, and both the anode and cathode external lead terminals were formed. Thus, the capacitor of this example was completed.

This embodiment is different from the first embodiment in that the anode lead 8 and the external anode lead terminal 12 are welded at the beginning of the manufacturing process and immediately after the pellet molding (step S20 in FIG. 4). In connection with this, when the external anode lead terminal and the external cathode lead terminal are attached to the capacitor element (step S80 in FIG. 4, FIG. 5D), the cathode conductor layer and the external cathode lead terminal are bonded. Is that it only needs to be done. In the present embodiment, the metal piece 12 (see FIG. 5B) of the anode terminal member 13 used in step S20 in FIG. 4 becomes an external anode lead terminal as it is.

Table 1 shows the leakage current defect rate and the capacitance appearance rate of the capacitor according to the present embodiment. Table 2 shows the results of a meniscographic examination of the solderability of the anode terminal member 13 (see FIG. 5C) after the formation of the silicone resin layer 17.

(Comparative Example 1) A capacitor different from that of Example 1 was manufactured by using the same pellets as in Example 1 and taking no measures to prevent crawling. That is, referring to FIG. 1 and FIG. 2, the same pellets 9 used in Example 1 are attached to the support material 10 by the same method as in Example 1 (FIG. 1 step S2, FIG. 2B). Thereafter, anodization was immediately performed to form a tantalum oxide film (Step S4 in FIG. 1).

A polypyrrole layer, a graphite layer, and a silver paste layer were sequentially formed on the pellet on which the tantalum oxide film had been formed in the same manner as in Example 1, then attached to the anode terminal member and the cathode terminal member, and packaged with resin. Then, lead molding was performed to complete the tantalum solid electrolytic capacitor of this comparative example.

Table 1 shows the defective rate of leakage current and the appearance rate of capacitance of the completed capacitor.

(Comparative Example 2) Using the same pellets as in Example 1, a capacitor different from that of Example 1 in that the creep-up preventing material is made of a polyfluorocarbon paste containing ethylene tetrafluoride as a main component. did. That is, referring to FIGS. 1 and 2, the same pellets used in Example 1 were used in Example 1
After attaching to the support member 10 in the same manner as described above, a tantalum oxide film was formed.

On the anode lead setting surface and the anode lead root of the pellet 9 having the tantalum oxide film formed thereon, 4
After a polyflon paste containing ethylene fluoride as a main component was applied, the paste was heated at 250 ° C. for one hour and cured to form a resin layer of tetrafluoroethylene.

The pellets were prepared in the same manner as in Example 1.
After forming the polypyrrole layer, graphite layer, silver paste layer, attached to the anode terminal member and the cathode terminal member,
A resin exterior was applied and lead molding was performed to complete a tantalum solid electrolytic capacitor of this comparative example.

Table 1 shows the leakage current defect rate and the capacitance appearance rate of the completed capacitor.

(Comparative Example 3) Using the same pellets as in Example 1, a capacitor different from that of Example 1 in that the creep-up preventing material was a thermosetting silicone resin. That is, referring to FIG. 1 and FIG. 2, the same pellets as used in Example 1 were attached to the support 10 in the same manner as in Example 1, and then a tantalum oxide film was formed.

A thermosetting silicone resin is applied to the anode lead planting surface and the anode lead base of the pellet 9 on which the tantalum oxide film is formed, and then heated and cured at 150 ° C. for 3 hours to form a silicone resin layer. did.

The pellets were prepared in the same manner as in Example 1.
After forming the polypyrrole layer, graphite layer, silver paste layer, attached to the anode terminal member and the cathode terminal member,
A resin exterior was applied and lead molding was performed to complete a tantalum solid electrolytic capacitor of this comparative example.

Table 1 shows the leakage current defect rate and the capacitance appearance rate of the completed capacitor.

Comparative Example 4 Using the same pellets as in Example 3, a capacitor different from that of Example 3 in that the creep-up preventing material was a thermosetting silicone resin. That is,
Referring to FIGS. 4 and 5 partially, using the same pellet 9 as in Example 3, the anode lead 8 was welded to the comb tooth-shaped metal piece (external anode lead terminal) 12 of the anode terminal member 13 ( FIG. 4 step S20, FIG. 5 (b)). This anode terminal member 13 has the same structure as that used in the third embodiment.

Next, a thermosetting silicone resin was applied to the anode lead planting surface and the anode lead root portion of the pellet 9 and cured by heating at 150 ° C. for 3 hours to form a silicone resin layer.

Thereafter, in the same manner as in Example 3, a tantalum oxide film, a polypyrrole layer, a graphite layer, and a silver paste layer were sequentially formed.

Next, the cathode conductor layer 4 and the external cathode lead terminal 14 of the cathode terminal member 15 are adhered to each other with a conductive adhesive 16. Then, the external lead terminals of the anode and the cathode were molded to complete the capacitor of the present example.

Table 1 shows the leakage current defect rate and the capacitance appearance rate of the capacitor according to this comparative example. The anode terminal member 13 after the formation of the silicone resin layer (see FIG. 5C)
Table 2 shows the results of examining the solderability of the sample by the meniscograph method.

[0064]

[Table 1]

[0065]

[Table 2]

Referring to Table 1, the capacitor (Comparative Example 1) having no creep-up prevention measures and the creep-up prevention material were 4
In the case of using ethylene fluoride as a main component (Comparative Example 2), the leakage current defect rate exceeds 90%, whereas the crawling prevention material is made of a thermosetting silicone resin capacitor (Comparative Examples 3 and 4). In addition, in the case of the ultraviolet-curable silicone resin (Examples 1, 2, and 3), the leakage current defective rate is about 10%. This indicates that the silicone resin reliably prevents the reaction liquid from climbing up to the anode lead during the formation of the polymer compound layer. However, Comparative Example 3,
No. 4 has a low leakage current defect rate, but has a capacity appearance rate of 80
%, Which is smaller than that of capacitors having other structures, which are around 95%.

For these reasons, when the water-repellent resin is a fluorine-based resin, it is difficult to reliably prevent a large climb due to a high wettability of the reaction liquid for forming a conductive polymer compound layer. On the other hand, when the water-repellent resin is a thermosetting silicone resin, it is possible to prevent the reaction liquid from climbing up, but the silicone resin whose viscosity has been reduced by heating at the time of curing can be introduced into the sintered body. It can be seen that a decrease in the capacity appearance rate due to permeation is inevitable.

On the other hand, in all of Examples 1 to 3, the leakage current defect rate is as low as about 10%, and the capacitance appearance rate is as high as 95%. This is because UV curing silicone resin does not require heating for its curing,
This is probably because the silicone resin hardly penetrates into the sintered body during the curing process.

Here, when the leakage current defect rates are compared between Example 1 and Example 2, there is no particular difference between the two. However, the structure in which anodizing is first performed to form a tantalum oxide film on the anode lead, and then a water-repellent resin layer is formed thereon (Example 2) is performed by forming the water-repellent resin layer first, and thereafter It is clear that the crawling during formation of the polymer compound layer can be prevented more reliably than the structure in which the tantalum oxide film is formed (Example 1).

Next, referring to Table 2, the zero-crossing time in the evaluation of solderability by the meniscograph method is shorter in Example 3 than in Comparative Example 4, indicating that the solderability is better. That is, in the third embodiment, the anode terminal member 13 (see FIG. 5B) welded to the anode lead 8 at the beginning of the manufacturing process (Step S20 in FIG. 4) can be used as it is as the external anode lead terminal of the capacitor. It is. This is because, when a thermosetting silicone resin is used as the water-repellent resin, the surface of the anode lead and the anode terminal member (see FIG. 4B) is oxidized by heating during the curing, whereas the ultraviolet rays are used. This is because the capacitor using the curable silicone resin (Example 3) does not receive heat when the resin is cured, so that such oxidation of the metal member does not occur. According to the manufacturing process of the second embodiment, the anode lead 8 is cut from the support member 10 (step S7 in FIG. 1) and re-welded to the anode terminal member 13 (step S8 in FIG. 1).
Can be omitted.

[0071]

As described above, the present invention uses a highly heat-resistant fluororesin such as ethylene tetrafluoride as a material for "preventing liquid crawling" when forming a solid electrolyte layer of a solid electrolytic capacitor. Also use a highly water-repellent silicone resin.
Thereby, according to the present invention, even in the case of a solid electrolytic capacitor using a reaction liquid for forming a conductive polymer compound layer having a higher creeping property than the semiconductor mother liquor of manganese dioxide, the creeping of the reaction liquid can be reliably prevented. .

In the present invention, among the silicone resins, an ultraviolet-curable silicone resin is used. UV curable silicone resin is different from thermosetting silicone resin.
No heating is required for curing. Therefore, according to the present invention, there is no decrease in the viscosity of the resin due to heating for curing, penetration into the porous sintered body, and no decrease in the capacity near the lead embedding surface. Capacitors can be provided.

The formation temperature of the conductive polymer compound layer is low,
In addition, since the heat load due to the irradiation of ultraviolet rays during curing of the silicone resin is small, the capacitor element does not substantially receive the heat history at room temperature or higher. Therefore, even if the anode lead and the external anode lead terminal are welded prior to the anodic oxidation for forming the dielectric oxide film, the welded portion and the metal surface do not oxidize or deteriorate, and It can be used as a lead terminal. Thus, according to the invention,
Since the cutting and re-welding of the anode lead can be omitted, a highly reliable solid electrolytic capacitor free of dielectric oxide film damage accompanying the work can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a manufacturing process flowchart showing an example of a manufacturing process sequence in a manufacturing method of the present invention.

FIG. 2 is a diagram showing the appearance of a capacitor manufactured according to the present invention in the order of manufacturing steps.

FIG. 3 is a manufacturing process flowchart showing another example of the manufacturing process order in the manufacturing method of the present invention.

FIG. 4 is a manufacturing process flowchart showing yet another example of the manufacturing process sequence in the manufacturing method of the present invention.

FIG. 5 is a diagram showing the appearance of a capacitor manufactured according to the present invention in the order of manufacturing steps.

FIG. 6 is a diagram showing the appearance of a solid electrolytic capacitor manufactured by a conventional manufacturing method in the order of manufacturing steps.

[Explanation of symbols]

 Reference Signs List 1 valve action metal (tantalum) 2 metal oxide film (tantalum oxide film) 3 solid electrolyte layer 4 conductor layer 5 graphite layer 6 silver paste layer 8 tantalum wire (anode lead) 9 pellet 10 support material 11 capacitor element 12 metal piece (outside) Anode lead terminal 13 Anode terminal member 14 Metal piece (external cathode lead terminal) 15 Cathode terminal member 16 Conductive adhesive 17 Silicone resin layer

Claims (1)

(57) [Claims] 1. An anode body forming step of forming a broadened anode body by implanting a valve action metal wire as an anode lead on a powder compact or foil of a valve action metal; An anode lead welding step of welding to a metal member including a part to be an external anode lead terminal for electrical connection with an oxide film forming step of forming an oxide film serving as a dielectric layer on the surface of the anode body A crawling prevention material disposing step of disposing a creepage preventing material made of a water-repellent resin on an anode lead setting surface of the anode body and a setting root portion of the anode lead; A solid electrolyte layer forming step of forming a solid electrolyte layer made of a conductive polymer compound.