JP4853966B2 - Solid electrolytic capacitor - Google Patents

Description

  The present invention relates to a solid electrolytic capacitor, and more particularly to an insulating water-repellent member that prevents creeping of a manganese nitrate aqueous solution used when forming a solid electrolyte layer.

  Conventionally, capacitors have been widely used in electronic circuits. Among capacitors, solid electrolytic capacitors are often used in power supply circuits and the like because of their relatively small size and large capacity.

For example, the solid electrolytic capacitor element has a structure as shown in FIG. As shown in FIGS. 3 (a) and 3 (b), this solid electrolytic capacitor element 1 has an anode formed on a porous sintered body 2 obtained by sintering a compression molded body made of valve metal powder such as tantalum. One end of the wire 5 is embedded or integrated by welding.
Further, an oxide film layer 3 made of, for example, Ta ₂ O ₅ and a solid electrolyte layer 4 made of a manganese dioxide layer are formed in the pores of the porous sintered body 2, and a carbon layer 6 as a cathode lead layer is formed thereon. And the silver layer 7 is formed.

  The solid electrolyte layer 4 is formed by immersing the porous sintered body 2 on which the oxide film layer is formed in a manganese nitrate aqueous solution for a certain period of time, followed by baking at 200 to 400 ° C. When the porous sintered body 2 is immersed in the aqueous manganese nitrate solution, the aqueous manganese nitrate solution crawls up on the anode wire 5 due to the surface tension of the liquid or capillary action, and a solid electrolyte layer is formed on the anode wire 5. Leakage current characteristics are likely to deteriorate.

Therefore, as shown in FIG. 3C, in order to prevent the manganese nitrate aqueous solution from creeping up, an insulating water repellent member ring 10 is generally inserted into the anode wire 5 (see, for example, Patent Document 1). Further, as shown in Patent Document 2 and the like, a liquid insulating water repellent is applied to the anode wire 5 in order to prevent the manganese nitrate aqueous solution from creeping up.
JP 2003-243258 A (column 0018 and symbol 9 in FIG. 1 and the like) JP 2002-270468 A

  However, in the conventional anode wire 5 described above, when the liquid insulating water repellent is applied, the insulating water repellent hangs down on the porous sintered body 2 through the anode wire 5, and the porous sintered body. There was a problem of penetrating into the two pores. Therefore, the solid electrolyte layer 4 cannot be embedded in the pores, and there is a problem that the capacitance, loss, equivalent series resistance, and leakage current characteristics deteriorate.

In the method using the insulating water repellent member ring 10, the diameter of the anode wire 5 (for example, 0.23 mm) and the diameter of the insertion hole of the insulating water repellent member ring 10 (for example, 0.25 mm) are approximately. Same diameter. Therefore, when inserted into the anode wire 5, the anode wire 5 and the insertion hole of the insulating water repellent member ring 10 are in surface contact with no allowance, and stress due to the surface contact causes the insulating water repellent member ring to There was a problem that the anode wire 5 was bent during the insertion, resulting in an assembly failure.
Further, during insertion of the insulating water-repellent member ring, mechanical stress is applied to the porous sintered body 2 through the anode wire 5, cracks are generated in the sintered body near the anode wire, and the oxide film layer is damaged. There was a problem that the leakage current characteristics deteriorated.

In order to solve the above problems, the present invention provides a solid electrolytic capacitor having an anode wire, comprising an insulating water-repellent member fitted to the anode wire, the insulating water-repellent member penetrating through the anode wire. When the insulating water-repellent member has a hole and is fitted to the anode wire through the through hole, the insulating water-repellent member and the anode wire are substantially in line contact with at least the upper end and the lower end of the through hole. It is configured as follows.

Also, with the anode wire and the insulating repellent member may be configured to contact substantially line in the middle portion of the through hole.

As described above, according to the present invention, when the insulating water repellent member is fitted to the anode wire through the through hole, the insulating water repellent member and the anode wire are at least at the upper end and the lower end of the through hole. It is comprised so that a substantially line contact may be carried out. That is, the insulating water-repellent member and the anode wire are configured to be in substantially line contact rather than the conventional surface contact.

  Thereby, the contact area of an insulating water repellent member and an anode wire reduces. Therefore, the stress applied to the anode wire during insertion of the insulating water repellent member into the anode wire is remarkably reduced, so that the anode wire is not bent. Furthermore, an oxide film layer and a solid electrolyte layer can be sequentially formed in a state where no cracks are generated in the porous sintered body.

  Therefore, it is possible to provide a solid electrolytic capacitor that is free from assembly failure and excellent in capacitance, loss, equivalent series resistance, and leakage current characteristics.

Hereinafter, a solid electrolytic capacitor according to the present invention will be described with reference to the drawings.
1A and 1B show a solid electrolytic capacitor according to the present invention, in which FIG. 1A is a partial cross-sectional view, and FIG. 1B is an enlarged cross-sectional view of a circular portion of a dashed line in FIG. 2A and 2B are cross-sectional views for explaining an insulating water-repellent member according to the present invention. FIG. 2A shows a reference example 1 and FIG. 2B shows a second embodiment.

As shown in FIG. 1, in the solid electrolytic capacitor element 1, one end of an anode wire 5 is embedded in a porous sintered body 2 obtained by sintering a compression molded body made of a valve action metal powder such as tantalum. It is integrated. For example, an oxide film layer 3 made of Ta ₂ O ₅ and a solid electrolyte layer 4 made of a manganese dioxide layer are formed in the pores of the porous sintered body 2, and a carbon layer 6 as a cathode lead layer and silver are formed thereon. Layer 7 is formed.
The solid electrolyte layer 4 is formed by immersing the porous sintered body 2 on which the oxide film layer is formed in a manganese nitrate aqueous solution for a predetermined time and then baking at 200 to 400 ° C. An insulating water repellent member 10 is inserted into the anode wire 5 to prevent the manganese nitrate aqueous solution from creeping up.

( Reference Example 1)
A solid electrolytic capacitor according to Reference Example 1 will be described with reference to FIG. The anode wire 5 has a wire diameter of 0.23 mm. The insulating water repellent member 10 is made of a tetrafluoroethylene resin and has, for example, a ring shape, and includes a cylindrical through hole 20 at substantially the center. The through hole 20 has an upper end 20a having a diameter of 0.25 mm and a lower end 20b having a diameter of 0.30 mm.
Here, in the through-hole 20, the lower end 20 b refers to an end disposed near the porous sintered body 2, whereas the upper end 20 a refers to an end disposed far from the porous sintered body 2. .

  First, an anode element in which one end of an anode wire 5 was embedded in a porous tantalum sintered body 2 was produced. Next, the insulating water repellent member 10 was inserted into the anode wire 5. Thereafter, an oxide film layer 3, a solid electrolyte layer 4, a carbon layer 6 and a silver layer 7 are sequentially formed on the porous sintered body 2, and the silver layer 7 and the cathode terminal are connected via a conductive adhesive. After connecting the anode terminal to the anode wire 5, the chip-shaped solid electrolytic capacitor 1 was produced by applying an exterior resin.

(Example 2)
A solid electrolytic capacitor according to Example 2 will be described with reference to FIG. The through hole 20 ′ of the insulating water repellent member 10 has an upper end 20a ′, a lower end 20b ′ and an intermediate portion 20c having a diameter of 0.25 mm, and the diameter between these 20a ′, 20b ′ and 20c is 0.30 mm. is there.
Therefore, through-hole 20 'is uneven | corrugated shape (ridge shape) in the range whose diameter is 0.25-0.30 mm. And after inserting the insulating water-repellent member 10 into the anode wire 5, the chip-shaped solid electrolytic capacitor 1 was produced similarly to the above-mentioned Reference Example 1.

(Conventional example 1)
Also in Conventional Example 1, the insulating water repellent member 10 was inserted into the anode wire 5. However, as shown in FIG. 3C, the hole diameter of the insulating water repellent member 10 is a uniform diameter of 0.25 mm. Thereafter, a chip-shaped solid electrolytic capacitor 1 was produced by the same method as in Reference Example 1 described above.

(Conventional example 2)
In the conventional example 2, a method of applying a liquid insulating water repellent to the anode wire 5 and baking and curing it was used. Thereafter, a chip-shaped solid electrolytic capacitor was produced by the same method as in Reference Example 1 described above.

(Comparative Example 1)
An anode element and a chip-shaped solid electrolytic capacitor were produced through the same steps as in Reference Example 1 described above. However, the insulating water-repellent member for preventing the manganese nitrate aqueous solution used for forming the solid electrolyte layer from creeping up is not used.

Table 1 shows the assembly failure rate and electrical characteristics of the solid electrolytic capacitors produced in Reference Example 1 and Example 2, Conventional Examples 1 and 2, and Comparative Example 1. 10000 capacitors each having a rating of 10V-22 μF were produced. The capacitance and loss were measured at 120 Hz, and the equivalent series resistance was measured at 100 kHz, and the average values are shown. The leakage current indicates an average value after applying the rated voltage for 1 minute. The occurrence rate of the liquid insulating water repellent dripping on the porous sintered body in Table 1 was calculated by confirming 10,000 solid electrolytic capacitor elements.

As shown in Table 1, Example 2 has better effects in terms of capacitance, loss, and equivalent series resistance than Conventional Example 2. In addition, the second embodiment has a better effect on the assembly failure rate and the leakage current than the first conventional example. As apparent from the comparison with Comparative Example 1, Example 2 is very effective in reducing the leakage current.

  The present invention is configured such that the insulating water-repellent member and the anode wire are brought into substantially line contact instead of conventional surface contact. The reason why the above effect is obtained is that the contact area between the insulating water-repellent member and the anode wire is reduced, so that the stress when inserting the insulating water-repellent member into the anode wire is extremely reduced, and the anode wire This is because the oxide film layer and the solid electrolyte layer can be sequentially formed in a state in which bending does not occur and cracks in the porous sintered body near the anode wire do not occur.

  In this example, tetrafluoroethylene resin was used as the insulating water repellent member, but among the tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin and the tetrafluoroethylene / hexafluoropropylene copolymer resin. Even if at least one is used, the same effect can be obtained.

The shape and size of the diameter of the through hole in the insulating water repellent member are not limited to the above embodiment. A similar effect can be obtained when at least the upper and lower ends of the through hole and the anode wire are in substantially line contact. Therefore, in addition to the upper and lower ends of the through-hole, it has good intermediate portion located between the upper and lower ends, even those that are in line contact.

  In the present invention, manganese dioxide is used as the solid electrolyte, but the same effect can be obtained even when a conductive polymer is used.

The solid electrolytic capacitor which concerns on this invention is shown, (a) is a partial cross section figure, (b) is an expanded sectional view of the circular part of the dashed-dotted line of (a). It is sectional drawing for demonstrating the insulating water-repellent member which concerns on this invention, (a) shows the reference example 1, (b) has shown Example 2. FIG. 1 shows a solid electrolytic capacitor of a conventional example, in which (a) is a partial cross-sectional view, (b) is an enlarged cross-sectional view of a dashed-dotted line portion, and (c) is a cross-sectional view for explaining an insulating water-repellent member. It is.

Explanation of symbols

1 Solid Electrolytic Capacitor 2 Porous Sintered Body 3 Oxide Film Layer 4 Solid Electrolyte Layer 5 Anode Wire 6 Carbon Layer 7 Silver Layer 10 Insulating Water-Repellent Member 20, 20 ′ Through Hole 20a, 20a ′ Upper Ends 20b, 20b of Through Hole 'Lower end 20c of through hole Middle part of through hole

Claims (2)

The solid electrolytic capacitor having an anode wire includes an insulating water-repellent member fitted to the anode wire, the insulating water-repellent member having a through hole that can be inserted into the anode wire, and the insulating water-repellent member. When the member is fitted to the anode wire through the through hole, the insulating water-repellent member and the anode wire are configured to make substantially line contact at least at the upper end and the lower end of the through hole. A solid electrolytic capacitor characterized in that 2. The solid electrolysis according to claim 1, wherein the insulating water-repellent member and the anode wire are configured to be in substantially line contact at an intermediate portion between an upper end and a lower end of the through hole. Capacitor.

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