JPH06252010A - Structure of solid electrolytic capacitor and manufacture thereof - Google Patents

Abstract

PURPOSE:To materialize downsizing in spite of large capacity and also, cut down the cost, in a solid electrolytic capacitor such as a tantalum solid electrolytic capacitor, etc. CONSTITUTION:A nonporous part 13, where metallic particles are fixed without space, is provided at one end of a chip piece 12 being made by sintering metallic particles such as tantalum, etc., so as to be porous, while a dielectric film such as of tantalum pentaoxide, etc., is made at the chip piece 12, and a solid electrolytic layer such as of manganese dioxide, etc., and a cathode film 18 are formed at the section excluding the nonporous part 13 out of the chip part 12, and an anode terminal film 19 is formed at the end face 12a on the side of the nonporous part 13 out of both end faces of the chip piece 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a solid electrolytic capacitor such as a tantalum solid electrolytic capacitor or an aluminum solid electrolytic capacitor which has a small size and a large capacity, and a method for producing the solid electrolytic capacitor.

[0002]

2. Description of the Related Art Conventionally, a capacitor element 1 in a solid electrolytic capacitor of this type is manufactured by the method described below. First, the metal particles such as tantalum are shown in FIG.
As shown in FIG. 2, the porous chip piece 2 is sintered, and the anode bar 3 made of metal such as tantalum is fixed to the chip piece 2.

This chip piece 2 is, as shown in FIG.
A direct current is applied in a state of being immersed in a chemical conversion solution such as phosphoric acid aqueous solution A to carry out anodization to form a dielectric film such as tantalum pentoxide 4 on the surface of each metal particle in the chip piece 2. In this case, the chip piece 2 is replaced with the phosphoric acid aqueous solution A.
By dipping the upper surface of the chip piece 2 into the outer peripheral surface of the base portion of the anode rod 3 by appropriately immersing the upper surface of the chip piece 2 in such a manner as to be submerged by a depth H from the liquid surface of the chemical conversion solution such as phosphoric acid aqueous solution A. Similarly, a dielectric film of tantalum pentoxide 4a or the like is similarly formed over a portion having a length H.

Next, the chip piece 2 after completing the step of forming the dielectric film such as the tantalum pentoxide 4, 4a is
As shown in FIG. 14, for the manganese nitrate aqueous solution B,
By dipping until the upper surface of the chip piece 2 does not become lower than the liquid surface of the manganese nitrate aqueous solution B, permeating the manganese nitrate aqueous solution B into the inside of the chip piece 2, and then lifting and firing it is repeated a plurality of times. On the surface of the dielectric film such as tantalum pentoxide 4
Or a solid electrolyte layer formed of an organic semiconductor film is formed on the surface of the dielectric film such as tantalum pentoxide 4 by a chemical polymerization method, an electrolytic oxidative polymerization method, or a gas phase polymerization method. To form.

Further, the capacitor element 1 is configured by forming a cathode film made of metal such as silver or nickel on the entire outer peripheral surface of the chip piece 2 excluding the upper surface through a graphat film or the like. There is. That is, the capacitor element 1 in the conventional solid electrolytic capacitor
When the dielectric film 4 such as tantalum pentoxide is formed on the surface of the metal particles in the chip piece 2, the outer peripheral surface of the root portion of the anode rod 3 fixed to the chip piece 2 is
By forming the dielectric film such as tantalum pentoxide 4a so as to be continuous with the dielectric film such as tantalum pentoxide 4 formed on the surface of the metal particles, the dielectric film such as tantalum pentoxide 4a is formed. The anode side of the anode rod 3 and the cathode side of the solid electrolyte layer such as manganese dioxide 5 are isolated (insulated).

For this reason, in the conventional solid electrolytic capacitor, the anode rod 3 protruding from the chip piece 2 cannot be cut off from the root portion thereof. Therefore, in the case of the conventional surface mount type solid electrolytic capacitor, For example,
Japanese Patent Publication No. 3-30977, and FIG.
As shown in FIG.
To the one lead terminal 6b of the pair of left and right lead terminals 6a and 6b, and the anode rod 3 protruding from the chip piece 2 to the other lead terminal 6a. 16, or the portion of the capacitor element 1 excluding the bottom surface of the chip piece 2 and the tip of the anode rod 3 is packaged with a covering material 8 such as synthetic resin as shown in FIG. , The cathode terminal portion 9b made of solder or the like on the bottom surface of the chip piece 2.
Is attached to the tip of the anode rod 3 by an anode terminal portion 9a made of solder or the like.
Are formed respectively.

[0007]

That is, in the conventional solid electrolytic capacitor, the capacitor element 1
Is packaged with the mold part 7 made of synthetic resin or the covering material 8 made of synthetic resin or the like, as described above, including both the chip piece 2 and the anode rod 3 protruding from the chip piece 2. Therefore, the entire size of the capacitor element 2 is larger than that of the capacitor element 2 by the amount by which the anode rod 3 is projected from the chip piece 2.
There is a problem that the volume efficiency is low, the volume is larger than the capacity, and the weight is increased.

Particularly, in the case of the surface-mounting type solid electrolytic capacitor shown in FIG. 15, when the chip portion 2 is packaged by the synthetic resin mold portion 7, a large stress is applied to the chip piece 2 so that the leakage current (LC ) Increases or short-circuit defects frequently occur. In other words, since the defective product rate is high, the yield rate in manufacturing is low, and furthermore, the synthetic resin mold portion 7 is formed,
In addition, the manufacturing process is complicated because the lead terminals 6a and 6b need to be bent, and the lead terminals 6a and 6b are fixed to the chip piece 2 and the anode rod 3, and the lead terminals 6a and 6b and the molded portion are complicated. 7, the material cost is considerably increased, so that the manufacturing cost is significantly increased in combination with the low yield rate in manufacturing as described above. Moreover, by packaging in the mold part 7, Since the weight balance becomes unbalanced, when ultrasonic cleaning is performed after mounting on a printed circuit board, etc.
There is a problem that both lead terminals 6a and 6b frequently come off the chip piece 2.

It is a technical object of the present invention to provide a structure of a solid electrolytic capacitor capable of solving these problems and a manufacturing method thereof.

[0010]

In order to achieve this technical object, the solid electrolytic capacitor according to the present invention is "a metal particle without gaps at one end of a chip piece obtained by sintering metal particles such as tantalum into a porous material. While providing a solidified non-porous portion, the tip piece, a dielectric film such as tantalum pentoxide, in the portion of the chip piece excluding the non-porous portion,
A solid electrolyte layer of manganese dioxide or the like and a cathode film are respectively formed, and an anode terminal film is formed on the end surface on the non-porous portion side of the left and right end surfaces of the chip piece. "."

Further, according to the manufacturing method of the present invention, "a non-porous portion obtained by solidifying metal particles without gaps is formed at one end of a chip piece obtained by sintering metal particles such as tantalum into a porous material, and then A step of forming a dielectric film such as tantalum pentoxide on the chip piece, a step of forming a solid electrolyte layer such as manganese dioxide, and a cathode film on a portion of the chip piece excluding the non-porous portion, respectively. On the other hand, one of the left and right end surfaces of the chip piece is subjected to surface processing to expose the metal particles to the end surface on the non-porous portion side, and then an anode terminal is formed on this end surface. It is something.

[0012]

[Operation] In this way, at one end of the chip piece,
By providing a non-porous portion in which metal particles are tightly solidified and forming a dielectric film such as tantalum pentoxide on the entire chip piece, when forming a solid electrolyte layer such as manganese dioxide on the chip piece, It is possible to prevent the formation of a solid electrolyte layer such as manganese dioxide on the surface of each metal particle in the non-porous portion, and to form a dielectric film such as tantalum pentoxide on the outer peripheral surface of the non-porous portion. By so doing, the anode side and the cathode side can be completely isolated (insulated). Therefore, in order to isolate (insulate) the anode side and the cathode side, as in the prior art, It is not necessary to fix the anode rod to one piece and form the dielectric film on the outer peripheral surface of the root portion of the anode rod.

[0013]

As described above, according to the present invention, unlike the prior art, it is not necessary to project the anode rod from the chip piece in the capacitor element, in other words, the conventional anode rod can be omitted. Since only the chip piece of the capacitor element needs to be packaged, the capacity and size are significantly larger and smaller than conventional ones.
The weight can be reduced.

In the case of the surface mounting type, FIG.
As shown in FIG. 5, since it is not necessary to fix the two lead terminals to the capacitor element and to package the whole in a synthetic resin mold part, it is possible to reliably reduce the occurrence of defective products. Since the material cost can be reduced and the number of processing steps can be reduced,
This has the effect of significantly reducing manufacturing costs.

[0015]

Embodiments of the present invention will be described below with reference to the drawings for manufacturing a tantalum solid electrolytic capacitor.
1 to 10 show a first embodiment. First, when tantalum particles are sintered into porous chip pieces 12 as shown in FIGS.
A non-porous portion 13 in which metal particles are hardened without a gap is provided in a portion having a dimension L at one end of 2.

The non-porous portion 13 is a chip piece 12
It is formed by partially heating the upper surface of the tantalum particles to a high temperature by irradiating a laser beam or the like to melt-bond the respective tantalum particles in a non-porous state. Then, as shown in FIG. 3, a tantalum wire 14 is fixed by welding to the end surface 12a on the non-porous portion 13 side of the both end surfaces 12a and 12b of the tip piece 12 by welding or heat resistant conductivity. After being fixed with the paste or the adhesive of Example 1, the chip piece 12 is immersed in a phosphoric acid aqueous solution A as shown in FIG. A dielectric film of tantalum pentoxide 15 is formed on the surface of each tantalum particle in.

The chip piece 12, which has been subjected to the step of forming the dielectric film of the tantalum pentoxide 15 as described above, is
As shown in FIG. 5, the manganese nitrate aqueous solution B was immersed in the chip pieces 12 up to the portion excluding the non-porous portion 13, and the manganese nitrate aqueous solution B was permeated into the chip pieces 12 and then lifted up. The tantalum pentoxide
A solid electrolyte layer of manganese dioxide 16 is formed on the surface of the dielectric film.

When the solid electrolyte layer of manganese dioxide 16 is formed, since the manganese nitrate aqueous solution B does not penetrate into the non-porous portion 13 of the chip piece 12, the non-porous portion 13 is formed. While it is possible to prevent the solid electrolyte layer of manganese dioxide 16 from being formed on the surface of each tantalum particle in the portion of the porous portion 13, a dielectric film of tantalum pentoxide 15 is formed on the outer peripheral surface of the non-porous portion 13. Therefore, each of them reliably separates (insulates) each tantalum particle in the non-porous portion 13 from the solid electrolyte layer of the manganese dioxide 16.
You can do it.

Then, as shown in FIG. 6, a silver film 1 is formed on the outer peripheral surface of the chip piece 12 excluding the non-porous portion 13 via a graphat film (not shown).
7 is formed, and the tantalum wire 14 is removed by cutting, peeling, or the like to form the capacitor element 11. Then, as shown in FIGS. 7 and 8, a metal cathode terminal film 18 made of solder or the like is formed on the surface of the silver film 17 in the capacitor element 11 (this cathode terminal film 18 is used in the capacitor element 11). It may be formed only on the bottom surface.) On the other hand, the chip piece 1
The end surface 12a on the non-porous portion 13 side of 2 is subjected to a surface processing of exposing each tantalum particle in the non-porous portion 13 to the end surface 12a by polishing the end surface 12a. The anode terminal film 19 is formed by soldering or the like.

The surface treatment may be performed by physical surface treatment by plasma or chemical surface treatment by chemical corrosion. Next, as shown in FIGS. 9 and 10, a heat-resistant synthetic resin or a part of the outer peripheral surface of the capacitor element 11 excluding the part of the cathode terminal film 18 and the anode terminal film 19 on the bottom surface thereof is used. By forming the coating film 20 made of glass, the surface mounted tantalum solid electrolytic capacitor is completed.

FIG. 11 shows a second embodiment. This second
In this example, the tantalum solid electrolytic capacitor is manufactured without tantalum wire without using tantalum wire as in the first embodiment. That is, after the chip piece 12 configured as shown in FIGS. 1 and 2 is oxidized in a gas phase of oxygen gas to form a tantalum pentoxide dielectric film, as shown in FIG. The manganese nitrate aqueous solution B is immersed in the chip piece 12 up to the portion excluding the non-porous portion 13, the manganese nitrate aqueous solution B is penetrated into the chip piece 12, and then lifted and fired a plurality of times. By repeating the above process, a solid electrolyte layer of manganese dioxide is formed on the surface of the dielectric film of tantalum pentoxide.

In this case, the chip piece 1
The manganese nitrate aqueous solution B is permeated into the tip 2 by applying the manganese nitrate aqueous solution B to the tip piece 12 by a dispenser or by contacting the tip piece 12 with a sponge body containing the manganese nitrate aqueous solution B in advance. Is also good. Then, after that, as in the case of the first embodiment, the formation of the silver film through the graphat film and the chip pieces 12 are performed.
In the surface mounting type tantalum solid electrolytic capacitor, surface processing is performed on the end surface 12a on the non-porous portion 13 side in the above, the metal cathode terminal film 18 and the anode terminal film 19 are formed by soldering, and the coating film 20 is formed. It is a finished product of.

In the first and second embodiments, the solid electrolyte layer is an organic semiconductor film, and this organic semiconductor film is formed by a chemical polymerization method, an electrolytic oxidative polymerization method or a gas phase polymerization method. It is okay.
In addition, although each of the above-described embodiments is a case of a tantalum solid electrolytic capacitor, the present invention is not limited to this, and it goes without saying that the present invention can be applied to other solid electrolytic capacitors such as an aluminum solid electrolytic capacitor.

[Brief description of drawings]

FIG. 1 is a perspective view of a chip piece used in a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a perspective view showing a state in which a tantalum wire is fixed to the chip piece in FIG.

FIG. 4 is a cross-sectional view showing a state in which a process for forming a dielectric film of tantalum pentoxide on the chip piece in FIG. 3 is being performed.

5 is a cross-sectional view showing a state in which a treatment for forming a solid electrolyte layer of manganese dioxide is performed on the chip piece in FIG.

6 is a perspective view showing a state where a silver film is formed on the chip piece in FIG. 5 after removing the tantalum wire.

FIG. 7 is a perspective view showing a state in which an anode terminal film and a cathode terminal film are formed on the chip piece of FIG.

8 is a sectional view taken along line VIII-VIII of FIG.

FIG. 9 is a perspective view of a tantalum solid electrolytic capacitor.

10 is an enlarged sectional view taken along line XX of FIG.

FIG. 11 is a diagram showing a second embodiment of the present invention.

FIG. 12 is a perspective view of a chip piece used in a conventional manufacturing method.

FIG. 13 is a cross-sectional view showing a state in which a process of forming a tantalum pentoxide dielectric film on the chip piece in FIG. 12 is being performed.

FIG. 14 is a cross-sectional view showing a state in which a process for forming a solid electrolyte layer of manganese dioxide in FIG. 13 is being performed.

FIG. 15 is a vertical cross-sectional front view showing a conventional tantalum solid electrolytic capacitor.

FIG. 16 is a vertical sectional front view showing another conventional tantalum solid electrolytic capacitor.

[Explanation of symbols]

11 Capacitor Elements 12 Chip Pieces 12a, 12b End Faces of Chip Pieces 13 Non-Porous Part 14 Tantalum Wire 15 Tantalum Pentoxide Dielectric Film 16 Manganese Dioxide Solid Electrolyte Layer 17 Silver Film 18 Cathode Terminal Film 19 Anode Terminal Film 20 Coating film

Claims (2)

[Claims] 1. A chip piece obtained by sintering metal particles such as tantalum into a porous piece is provided with a non-porous portion in which metal particles are hardened without a gap, while the chip piece is provided with a dielectric material such as tantalum pentoxide. Body film, in the portion excluding the non-porous portion of the chip piece, a solid electrolyte layer such as manganese dioxide and a cathode membrane are respectively formed, and the non-porous portion side of the left and right end surfaces of the chip piece. A solid electrolytic capacitor structure characterized in that an anode terminal film is formed on the end face. 2. A non-porous portion formed by solidifying metal particles without a gap is formed at one end of a chip piece obtained by sintering metal particles such as tantalum into a porous material, and then tantalum pentoxide or the like is formed on the chip piece. The step of forming a dielectric film, the step of forming a solid electrolyte layer of manganese dioxide or the like, and the step of forming a cathode film on the portion excluding the non-porous portion of the chip piece, while A method for producing a solid electrolytic capacitor, characterized in that, of the both end surfaces, an end surface on the non-porous portion side is subjected to surface processing for exposing metal particles to the end surface, and then an anode terminal is formed on the end surface.