JP3378285B2 - Structure of solid electrolytic capacitor and method of 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 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, as shown in FIG. 13 , metal particles of tantalum or the like are sintered on a porous chip piece 2, and an anode rod 3 made of metal such as tantalum is fixed to the chip piece 2.

As shown in FIG. 14 , this chip piece 2 is
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 a 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 tantalum pentoxide 4, 4a
As shown in FIG. 15 , with respect to 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 baking, is repeated a plurality of times. A solid electrolyte layer formed of a metal oxide such as manganese dioxide 5 is formed 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. The layer is formed by a chemical polymerization method, an electrolytic oxidative polymerization method, or a gas phase polymerization method.

Further, the capacitor element 1 is constructed 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, in the capacitor element 1 of the conventional solid electrolytic capacitor, when the dielectric film 4 such as tantalum pentoxide is formed on the surface of the metal particles of the chip piece 2, the anode rod 3 fixed to the chip piece 2 is formed. A tantalum pentoxide 4 having a dielectric film such as tantalum pentoxide 4a formed on the surface of the metal particles also on the outer peripheral surface of the root portion of
By forming the dielectric film such as tantalum pentoxide 4a so as to be continuous, the anode side of the anode rod 3 and the cathode side of the solid electrolyte layer such as manganese dioxide 5 are separated by the dielectric film such as tantalum pentoxide 4a. It is configured to (insulate).

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 lead terminals 6b of the pair of left and right lead terminals 6a and 6b, and the anode rod 3 protruding from the chip piece 2 is fixed to the other lead terminal 6a. 17 , or as shown in FIG. 17 , 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. , 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.

[0010]

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.

In particular, in the case of the surface mount type solid electrolytic capacitor shown in FIG. 16 , when the synthetic resin mold portion 7 is used for packaging, a large stress acts on the chip piece 2 to cause 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 often 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.

[0013]

In order to achieve this technical object, the solid electrolytic capacitor according to the present invention has a structure in which "a metal particle such as tantalum is attached to one end surface of a chip piece obtained by porously sintering metal particles such as tantalum. Porous sintered gold
The metal piece is fixed by sandwiching a metal plate piece such as tantalum between the metal piece and the chip piece , the metal piece and the metal plate piece.
A dielectric film such as tantalum pentoxide is formed on the surface , a solid electrolyte layer such as manganese dioxide and a cathode film are formed on the chip piece, and an anode terminal film is formed on the end surface of the metal piece. "."

Further, the production method of the present invention, the metal particles "tantalum on one end surface of the porous sinter chip pieces, the metal pieces by sintering a porous metal particles such as tantalum, in the meantime Fix by sandwiching metal plate pieces such as tantalum
And then the chip piece , the metal piece and the
A step, the step of subjecting each forming a solid electrolyte layer and a cathode layer, such as manganese dioxide to said tip piece for forming a dielectric film such as tantalum pentoxide with respect to the metal plate piece,
The method is characterized by further comprising: a step of subjecting an end surface of the metal piece to a surface treatment for exposing a metal surface of the metal piece to the end surface; and a step of forming an anode terminal on the end surface. It is something.

[0015]

[For work] With this structure, the porous
Solid electrolyte layer such as manganese dioxide for high quality chip pieces
When forming, each tantalum in the metal piece
Solid electrolyte layer of manganese dioxide on the surface of metal particles such as
The metal plate piece reliably prevents the formation of
This is done, and therefore the anode side at the end face of the metal piece
And the cathode side of the solid electrolyte layer, the porous metal
Since it can be completely isolated (insulated) by the piece and the metal plate piece, in order to separate (insulate) the anode side and the cathode side, the anode bar is fixed to the chip piece as in the conventional case. Therefore, it is not necessary to form a dielectric film on the outer peripheral surface of the root portion of the anode rod.

[0016]

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 with the metal piece in the capacitor element needs to be packaged, the capacity and the size and the weight can be significantly reduced as compared with the conventional one.

Further, in the case of the surface mount type, FIG.
As shown in FIG. 7, since it is not necessary to fix the capacitor element to the two lead terminals and to package the whole in a synthetic resin mold part, it is possible to surely reduce the number 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.

[0018]

Embodiments of the present invention will be described below with reference to the drawings for manufacturing a tantalum solid electrolytic capacitor.

1 to 11 show a first embodiment.

First, as shown in FIG. 1, on the upper surface of a chip piece 12 formed by sintering tantalum particles into a porous structure, a metal piece 13 formed by similarly sintering tantalum particles into a porous structure is formed. Gold made of tantalum between the piece 13 and the chip piece 12
The metal plate pieces 14 are overlapped with each other with the metal plate pieces 14 sandwiched therebetween, and these are welded to each other as shown in FIGS. 2 and 3, or bonded with a heat-resistant conductive paste or adhesive. In this case, the three members may be stacked before the sintering and then sintered in this stacked state.

Then, as shown in FIG. 4, a tantalum wire 15 is fixed by welding to the upper surface 13a of the metal piece 13 bonded to the chip piece 12, or a heat-resistant conductive paste or adhesive is used. Then, the whole chip piece 12 provided with the metal piece 13 and the metal plate piece 14 is
As shown in FIG. 5, while immersed in the phosphoric acid aqueous solution A,
By applying a direct current to carry out anodization, the surface of each tantalum particle in the chip piece 12, the surface of each tantalum particle in the metal piece 13 , and the surface of the metal plate piece 14 are tantalum pentoxide. 16 dielectric films are formed.

The metal piece 13 and the gold having completed the step of forming the dielectric film of tantalum pentoxide 16 as described above.
As shown in FIG. 6, the chip piece 12 provided with the metal plate piece 14 was treated with respect to the manganese nitrate aqueous solution B.
Dip only the manganese nitrate aqueous solution B into the chip pieces 12
The solid electrolyte layer of manganese dioxide 17 is formed on the surface of the dielectric film of tantalum pentoxide 16 in the chip piece 12 by repeating the process of penetrating into the inside of the chip and then lifting and firing it several times.

When the solid electrolyte layer of manganese dioxide 17 is formed, the metal plate piece 14 can prevent the metal manganese nitrate aqueous solution B from penetrating into the metal piece 13, whereby each metal piece 13 can be prevented. Since it is possible to prevent the solid electrolyte layer of manganese dioxide 17 from being formed on the surface of the tantalum particles, each tantalum particle in the metal piece 13 and the solid electrolyte layer of manganese dioxide 17 formed in the chip piece 12 can be securely formed. It can be isolated (insulated).

Next, as shown in FIG. 7, a silver film 18 is formed on the outer peripheral surface of the chip piece 12 excluding the metal piece 13 and the metal plate piece 14 via a graphat film (not shown). And the tantalum wire 15 is removed by cutting, peeling or the like to form the capacitor element 11.

Then, as shown in FIGS. 8 and 9, a metallic cathode terminal film 19 is formed on the surface of the silver film 18 in the capacitor element 11 by soldering or the like (this cathode terminal film 19 is a capacitor). The metal piece 1 may be formed only on the bottom surface of the element 11.
By polishing the upper surface 13a of No. 3, the metal piece 1
The surface treatment of exposing each tantalum particle in No. 3 to the upper surface 13a is performed, and then the upper surface 13a is subjected to a base treatment for improving solder wettability such as nickel plating, and then the anode terminal film by solder or the like. Form 20.

The surface treatment may be performed by physical surface treatment with plasma or chemical surface treatment by chemical corrosion.

Next, with respect to a part of the outer peripheral surface of the capacitor element 11 except the part of the cathode terminal film 19 and the anode terminal film 20 on the bottom surface thereof, FIG.
Further, as shown in FIG. 11, by forming a coating film 21 made of heat resistant synthetic resin or glass, a surface mounted tantalum solid electrolytic capacitor is completed.

FIG. 12 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, the chip piece 12 provided with the metal piece 13 and the metal plate piece 14 configured as shown in FIGS. 2 and 3 is oxidized in the gas phase of oxygen gas to obtain tantalum pentoxide. After forming the dielectric film, as shown in FIG. 12, only the chip piece 12 is immersed in the manganese nitrate aqueous solution B to form the manganese nitrate aqueous solution B.
The solid electrolyte layer of manganese dioxide is formed on the surface of the dielectric film of tantalum pentoxide only for the chip piece 12 by penetrating the inside of the chip piece 12 and then lifting and baking the same.

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 12 by a dispenser or by contacting the tip 12 with a sponge body containing the manganese nitrate aqueous solution B in advance. Is also good.

Then, thereafter, as in the case of the first embodiment, the silver film is formed through the graphat film, the upper surface 13a of the metal piece 13 is surface-processed, and the metal cathode terminal film 19 is formed by soldering or the like. By forming the anode terminal film 20 and the coating film 21, the surface-mounted tantalum solid electrolytic capacitor is completed.

In the case of this second embodiment,
Uses the solid electrolyte layer as an organic semiconductor film, and
The body membrane is processed by a chemical polymerization method, an electrolytic oxidative polymerization method, or a gas phase.
It may be formed by a polymerization method .

The present invention also relates to the tantalum solid of the above embodiment.
Not limited to the case of body electrolytic capacitors, aluminum solid electrolytic capacitors
Suitable for other solid electrolytic capacitors such as capacitors
Needless to say, it can be used .

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a state where a metal piece is fixed to the chip piece in FIG.

FIG. 3 is a sectional view taken along line III-III in FIG.

FIG. 4 is a perspective view showing a state in which a tantalum wire is fixed to the chip piece in FIG.

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

FIG. 6 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.

FIG. 7 is a perspective view showing a state where a silver film is formed on the chip piece in FIG. 6 after removing the tantalum wire.

8 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.

9 is a sectional view taken along line IX-IX in FIG.

FIG. 10 is a perspective view of a tantalum solid electrolytic capacitor.

FIG. 11 is an enlarged sectional view taken along line XI-XI of FIG. 9.

FIG. 12 is a cross-sectional view showing a state in which a treatment for forming a solid electrolyte layer of manganese dioxide is being performed in the second embodiment of the present invention.

FIG. 13 is a perspective view of a chip piece used in a conventional manufacturing method.
Is .

14] A tantalum pentoxide is added to the chip piece in FIG.
Sectional view of the process of forming the dielectric film
Is.

15 is a solid state electrode of manganese dioxide in FIG.
FIG. 4 is a cross-sectional view showing a state where a treatment for forming a degrading layer is being performed.
It

FIG. 16: Conventional tantalum solid electrolytic capacitor
FIG .

FIG. 17 is another conventional tantalum solid electrolytic capacitor.
It is a vertical section front view showing a sir.

[Explanation of symbols]

11 Capacitor Element 12 Chip Piece 13, 13 'Metal Piece 14 Metal Plate Piece 15 Tantalum Wire 16 Tantalum Pentoxide Dielectric Film 17 Manganese Dioxide Solid Electrolyte Layer 18 Silver Film 19 Cathode Terminal Film 20 Anode Terminal Film 21 Coating Film

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01G 9/052 H01G 9/012 H01G 9/00

Claims (2)

(57) [Claims] 1. A chip piece obtained by sintering metal particles such as tantalum into a porous material is provided with metal particles such as tantalum on one end surface thereof.
A metal piece such as tantalum is sandwiched between metal pieces that have been sintered into a porous structure.
The chip piece , the metal piece and the metal piece
And a dielectric film such as tantalum pentoxide on the surface of the metal plate piece, a solid electrolyte layer such as manganese dioxide and a cathode film are formed on the chip piece, and an anode terminal film is formed on the end surface of the metal piece. A solid electrolytic capacitor structure characterized by being formed. 2. A chip piece obtained by sintering metal particles such as tantalum into a porous piece, and a metal piece obtained by sintering metal particles such as tantalum into a porous plate on one end surface of the chip piece , and a metal plate made of tantalum or the like therebetween.
A step of sandwiching and fixing the piece , and then the chip piece ,
Forming a dielectric film such as tantalum pentoxide with respect to serial metal piece and the metal plate piece, a step of subjecting each forming a solid electrolyte layer and a cathode layer, such as manganese dioxide to the tip piece, A step of subjecting the end surface of the metal piece to a surface treatment for exposing the metal surface of the metal piece to the end surface ;
And, it has a step of forming an anode terminal to the end face
Method for producing a solid electrolytic capacitor, characterized in that that.