JP2001274041A - Solid electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid electrolytic capacitor in which a dielectric layer, a solid electrolyte layer, and a cathode lead-out layer are successively formed outside an anode member provided with an anode lead pin implanted upright at its one edge, where a reduction in ESR(equivalent series resistance) and a reduction in LC(leakage current) are set compatible with each other. SOLUTION: In this solid electrolytic capacitor, the edge of an anode member on which an anode lead pin is implanted is formed like a protuberant curved surface such as the shape of a roof, and the dielectric layer, solid electrolyte layer, and cathode lead-out layer are successively formed on the edge of the anode member on which an anode lead pin is implanted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolytic capacitor in which a dielectric layer, a solid electrolyte layer and a cathode lead layer are sequentially formed outside an anode member having an anode lead pin planted thereon.

[0002]

2. Description of the Related Art As a chip type solid electrolytic capacitor suitable for surface mounting on a printed wiring board or the like, one having a configuration as shown in FIG. 9 is known.

In this solid electrolytic capacitor, an anode member 1 made of a sintered body of a valve metal (tantalum, niobium, titanium, aluminum, etc.) is provided outside a dielectric layer 2 made of an electrolytic oxide film of the anode member. A capacitor element 14 is formed by sequentially forming a solid electrolyte layer 3 made of manganese, a TCNQ complex salt, a conductive polymer, and the like, and a cathode extraction layer 4 made of conductive carbon, silver, and the like. The anode lead terminal 51 is welded to the anode lead pin 15 and the cathode lead terminal 5 is attached to the cathode lead layer 4.
2 is soldered, and the outer periphery of the capacitor element 14 is covered and sealed with an outer shell layer 7 made of epoxy resin or the like.

The dielectric layer 2 is formed not only on the outer periphery of the anode member 1 but also on the root of the anode lead pin 15, but is not formed on the connection between the anode lead pin 15 and the anode lead terminal 51.

The cathode extraction layer 4 is formed by applying conductive carbon dissolved in an organic solvent to the outside of the solid electrolyte layer 3 and drying it, and further applying silver (a so-called silver paste) dissolved in the organic solvent to the outside. Then, drying is performed to form a layer in which a layer containing conductive carbon and a layer containing silver are sequentially laminated.

[0006] However, the cathode lead layer 4 is the anode lead pin 1
5 to prevent the LC (leakage current) as a finished capacitor from increasing due to contact with the trunk portion (the portion where the dielectric layer 2 is not formed or its formation is insufficient). In many cases, the cathode extraction layer 4 is not formed on the top surface (the surface on which the anode lead pins 15 are implanted) T.
(This is also described in JP-A-9-97747.)

[0007]

SUMMARY OF THE INVENTION On the other hand, the inventor of the present application has
Capacitor element 14 having an outer shape as shown in FIG.
Next, a cathode extraction layer was formed under the conditions shown in Table 1, and a solid electrolytic capacitor having the structure shown in FIG. 9 was finished. Tanδ (tangent of loss angle) and E
In order to reduce SR (equivalent series resistance), it has been found that it is effective to increase the contact area between the cathode extraction layer and the solid electrolyte layer.

[0008]

[Table 1]

[0009]

[Table 2]

FIG. 10C shows the capacitor element 14 viewed from the top surface (the surface on which the anode lead pins 15 are implanted) T, and FIG. 10B shows the capacitor element 14 viewed from the side surface S.
Indicates a position viewed from the bottom surface B, and L shown in Table 2
The C yield was LC ≦ 94.5 μ among tens of samples prepared.
It shows the ratio of those that were A.

As can be seen by comparing Tables 1 and 2,
As the contact area between the cathode extraction layer and the solid electrolyte layer increases, tan δ and ESR decrease, but in the conventional example 5 in which the cathode extraction layer is formed even on the anode lead pin planting surface, the LC yield is poor. I have.

The present invention provides a solid electrolytic capacitor in which a dielectric layer, a solid electrolyte layer and a cathode lead layer are sequentially formed on the outside of an anode member having an anode lead pin implanted on one end surface thereof, in which ESR and LC are reduced. And to balance.

[0013]

According to the present invention, there is provided a solid electrolytic capacitor having a dielectric layer, a solid electrolyte layer, and a cathode lead layer formed sequentially on the outside of an anode member having an anode lead pin planted at one end. In the above, the anode lead pin planting end of the anode member is formed of a curved surface or a connecting surface raised in a roof shape, and the anode lead pin planting end of the anode member also has the dielectric layer, the solid electrolyte layer, and the cathode extraction layer. Are sequentially formed.

According to the configuration of the present invention, even if a dielectric layer, a solid electrolyte layer, and a cathode lead layer are sequentially formed on the anode lead pin planting end of the anode member in order to reduce ESR,
The cathode extraction layer is unlikely to contact the trunk of the anode lead pin (the portion where the dielectric layer is not formed or the dielectric layer is insufficiently formed), thereby suppressing an increase in LC.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a solid electrolytic capacitor according to an embodiment of the present invention has an anode member 1 made of a sintered body of a valve metal (tantalum, niobium, titanium, aluminum, etc.). Outside, a dielectric layer 2 composed of an electrolytic oxide film of the anode member, manganese dioxide, TCNQ complex salt,
A capacitor element 14 is formed by sequentially forming a solid electrolyte layer 3 made of a conductive polymer or the like and a cathode extraction layer 4 made of conductive carbon, silver or the like, and the anode lead pin 15 planted at one end of the anode member 1 is connected to the anode lead pin 15. In a solid electrolytic capacitor in which the anode lead terminal 51 is welded, the cathode lead terminal 52 is soldered to the cathode lead layer 4, and the outer periphery of the capacitor element 14 is covered and sealed with an outer shell layer 7 made of epoxy resin or the like. The anode lead pin planting end T of the anode member 1 is formed of a curved surface or a connecting surface raised in a roof shape, and the anode lead pin planting end of the anode member 1 is also provided with the dielectric layer 2, the solid electrolyte layer 3, and the cathode. It is characterized in that the extraction layers 4 are sequentially formed.

The manganese dioxide layer as the solid electrolyte layer 3 is formed by a method such as thermal decomposition of manganese nitrate.
The CNQ complex salt layer is formed by a melt impregnation method of the TCNQ complex salt, and the conductive polymer layer is formed of pyrrole, thiophene,
It is formed by chemical oxidation polymerization or electrolytic oxidation polymerization of aniline or a derivative thereof.

Although not explicitly shown in FIG. 1, the dielectric layer 2 and the solid electrolyte 3 are formed by penetrating into minute internal voids of the sintered body constituting the anode member 1.

The cathode extraction layer 4 is formed by applying a conductive carbon dissolved in an organic solvent to the outer periphery of the solid electrolyte layer 3 and drying it, and further forming a silver (so-called silver paste) dissolved in the organic solvent on the outer periphery. Is applied and dried to form a structure in which a layer containing conductive carbon and a layer containing silver are sequentially laminated.

At this time, in order to apply a silver paste having an appropriate thickness to the bottom surface B, the side surface S, and the anode lead pin planting surface T of the capacitor element 14, as shown in FIG. The capacitor element 14 formed with each layer of
Immersed in a relatively high-viscosity (50-300 poise) silver paste 40 stored in the tank 8 or the capacitor element 14.
Is vibrated in a direction perpendicular to the liquid surface of the silver paste 40, and the vibration is controlled so that the liquid surface of the silver paste 40 reaches the root of the anode lead pin 15 when the capacitor element 14 is deepest. A method of pulling out the capacitor element 14 from the silver paste 40 while continuing the vibration (see Japanese Patent Application No. 9-280152 by the present applicant) is effective.

Here, when a conventional anode member having an anode lead pin planting end having a planar shape is used, as shown in FIG. It is not so easy to control the vibration so that the liquid level of the anode lead pin 15 reaches the root part. When the paste is poor, the silver paste may form the trunk of the anode lead pin (whether or not a dielectric layer is formed or not). Is insufficient).

Further, when the capacitor element 14 is pulled out of the silver paste tank 8, the silver paste having a relatively high viscosity is unlikely to flow down from the anode lead pin setting surface of the capacitor element. In some cases, the silver paste layer is formed thicker than the bottom and side surfaces of the silver paste.

In order to solve such a problem, if an anode member having the anode lead pin planting end raised in a roof shape according to the present invention is used, the anode lead pin planting end of the capacitor element is also provided.
A silver paste layer can be formed with substantially the same thickness as the bottom surface and side surfaces. The silver paste layer is formed on the trunk portion of the anode lead pin (where the dielectric layer is not formed or the dielectric layer is insufficiently formed).
Difficult to contact with.

As the roof-shaped configuration of the lead pin planting end of the anode member, a pyramid as shown in FIG. 3, a cone as shown in FIG. 4, a dome as shown in FIG. 5, and a dome as shown in FIG. A deformed shape such as a squib-like shape, a gable shape as shown in FIG. 7, and a ridge shape as shown in FIG. 8 is possible. 3 to 8,
[A] shows the anode member 1 viewed from the top surface (the surface on which the anode lead pins 15 are planted), [b] shows the front member, and [c] shows the right member. . The end of the anode member 1 on which the anode lead pin is planted has a connecting surface or a curved surface, and the anode lead pin 15 is implanted on the top or ridge.

The anode lead terminal 51 is connected to the anode lead pin 15 by resistance welding.
The cathode lead terminal 52 is connected to the cathode extraction layer 4 by brazing.

The outer shell resin layer 7 is formed by an injection molding method such as a transfer molding method and an injection molding method. The end portions of the anode lead terminal 51 and the cathode lead terminal 52 are bent along the outer periphery after the outer shell resin layer 7 is formed.

Hereinafter, more specific examples will be described.

[0027]

Embodiment 1 In Embodiment 1, an anode member 1 having a pyramid-shaped anode lead pin end (see FIG. 3) is used. The anode member 1 is made of a sintered body of tantalum, and the anode lead pins are also made of a tantalum material.

Next, after a dielectric layer 2 is formed by electrolytically oxidizing the anode member 1, a pyrrole monomer and an oxidizing agent are acted on the dielectric layer 2, thereby forming a conductive polymer layer 3 as a lower layer. A chemically polymerized polypyrrole film is formed, and is further immersed in a solution containing a pyrrole monomer and an oxidizing agent, and is energized to form an electropolymerized polypyrrole film as an upper layer of the conductive polymer layer 3.

Next, a layer containing conductive carbon and a layer containing silver are sequentially laminated to form a cathode extraction layer 4, and anode and cathode lead terminals 51, 51 are attached. The outer shell layer 7 is formed by housing and injecting an epoxy resin.

Finally, while applying the rated voltage,
Aging treatment for 2 hours to complete a solid electrolytic capacitor.

[0031]

Second Embodiment In a second embodiment, a solid electrolytic capacitor is completed through the same steps as in the first embodiment except that an anode member 1 having a dome-shaped anode lead pin planting end (see FIG. 5) is used. .

Table 3 shows various characteristics of the solid electrolytic capacitors according to Examples 1 and 2.

[0033]

[Table 3]

Here, the external dimensions of the capacitor elements in the first and second embodiments are substantially the same as those in the above-mentioned conventional examples 1 to 5 (see FIG. 6). The manufacturing method is the same as in Examples 1 and 2, except for the structure of the anode member and the location where the cathode extraction layer is formed.

As can be seen by comparing each of the embodiments shown in Table 3 with each of the conventional examples shown in Table 2, the E of Embodiments 1 and 2 can be understood.
SR is smaller than the conventional examples 1 to 4 in which the cathode lead layer is not formed at the anode lead pin planting end of the capacitor element. The LC yield is such that the cathode lead layer is formed on the flat anode lead pin planting surface. This is greatly improved as compared with the formed conventional example 5.

[0036]

According to the present invention, ESR is reduced in a solid electrolytic capacitor in which a dielectric layer, a solid electrolyte layer and a cathode lead layer are sequentially formed outside an anode member having an anode lead pin planted at one end. Therefore, even if a dielectric layer, a solid electrolyte layer, and a cathode lead layer are sequentially formed on the anode lead pin planting end of the anode member, the cathode lead layer is formed by the trunk of the anode lead pin (whether or not a dielectric layer is formed or not). ), And the increase in LC is suppressed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a solid electrolytic capacitor according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram for explaining a cathode extraction layer forming step.

FIG. 3 is a [a] top view, [b] front view, and [c] right side view of the anode member used in the embodiment of the present invention.

FIG. 4 is a [a] top view, [b] front view, and [c] right side view of the anode member used in the embodiment of the present invention.

5A is a top view, FIG. 5B is a front view, and FIG. 5C is a right side view of the anode member used in the embodiment of the present invention.

FIG. 6 is a [a] top view, [b] front view, and [c] right side view of the anode member used in the embodiment of the present invention.

FIG. 7 is a [a] top view, [b] front view, and [c] right side view of the anode member used in the embodiment of the present invention.

FIG. 8 is a [a] top view, [b] front view, and [c] right side view of the anode member used in the embodiment of the present invention.

FIG. 9 is a sectional view of a conventional solid electrolytic capacitor.

FIG. 10 is a [a] bottom view, [b] side view, and [c] top view of the capacitor element.

FIG. 11 is a conceptual diagram for explaining a cathode extraction layer forming step in a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode member 14 Capacitor element 15 Anode lead pin 2 Dielectric layer 3 Solid electrolyte layer 4 Cathode lead layer 51 Anode lead terminal 52 Cathode lead terminal 7 Outer shell resin layer

Claims (3)

[Claims] 1. A solid electrolytic capacitor in which a dielectric layer, a solid electrolyte layer and a cathode lead layer are sequentially formed outside an anode member having an anode lead pin implanted at one end thereof, wherein the anode lead pin implanted end of the anode member is A solid electrolytic capacitor comprising a curved surface or a connecting surface raised in a roof shape, wherein the dielectric layer, the solid electrolyte layer and the cathode lead layer are sequentially formed also on the anode lead pin planting end of the anode member. . 2. The anode lead pin planting end of the anode member is raised into a roof shape selected from a pyramid shape, a conical shape, a dome shape, a semicylindrical shape, a gable shape, and a ridge shape, and a top or a ridge of the roof shape. The solid electrolytic capacitor according to claim 1, wherein the anode lead pin is planted in a portion. 3. The solid electrolyte layer is made of a conductive polymer, and the cathode extraction layer has a structure in which a layer containing conductive carbon and a layer containing silver are sequentially laminated. The solid electrolytic capacitor as described.