JP3131030B2 - Manufacturing method of 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. More specifically, the present invention relates to a method for manufacturing a solid electrolytic capacitor capable of easily protruding an electrode wire having a very small diameter.

[0002]

2. Description of the Related Art In a conventional method of manufacturing a solid electrolytic capacitor, when an electrode wire is protruded from a valve metal molding, as shown in FIG. The cavity of the mold is filled with a valve metal powder 53 such as tantalum (see FIG. 5A),
Next, the upper mold 55 holding the wire 54 is fitted into the cavity so that the wire 54 is inserted into the powder 53, and at the same time, the powder 53 is compressed to form a compact 56 (FIG. 5).
(B)). After that, the upper mold 55 is removed while leaving the wire 54 (see FIG. 5C). After cutting the wire 54, the lower mold 51 is pushed up to take out the molded body 56 from which the wire 54 protrudes ((FIG. 5 (C)). d)).

[0003]

However, in general, the particle diameter of the valve metal powder is 0.03 to 0.1 mm, and some of them may be agglomerated, while the wire has an outer diameter of 0.1 mm.
Since the wire is formed to be about 2 mm, the wire is not easily inserted into the powder in contact with the particles. Furthermore, since the powder is compressed at the same time as the insertion of the wire, the insertion resistance increases, and it is extremely difficult to attach the wire in a sound state, resulting in a defective product or a large number of steps. That is, there is a problem that the wire is not inserted to a predetermined depth, and is bent or broken. Further, there is a problem that the wire is not sufficiently inserted, the wire comes off in a later step or use, and reliability is reduced.

The present invention has been made to solve such a problem, and the wire is easily inserted into the powder,
Further, it is an object of the present invention to provide a method of manufacturing a solid electrolytic capacitor in which powders are sintered in a sound state, defective products are significantly reduced, and the yield is improved.

[0005]

According to a first aspect of the present invention, there is provided a method of manufacturing a valve metal having a protruding electrode wire and sintering the molded body. A method for manufacturing a solid electrolytic capacitor in which a body film, a metal oxide layer, and a conductor layer are formed in this order, and in forming the molded body, filling the valve metal powder into a molding die, A guide hole having a predetermined depth into which the wire is to be inserted is formed therein, and after the wire is inserted into the guide hole, the powder is compressed and formed to form a molded body on which the wire protrudes. It is characterized by:

On the other hand, in the manufacturing method of the second invention (invention of claim 2), a molded body of a valve action metal on which an electrode wire is protruded is sintered, and a dielectric film and a metal oxide layer are formed on its outer surface. And a conductor layer are formed in this order, the method for manufacturing a solid electrolytic capacitor, when forming the molded body, filling the mold metal with the valve metal powder, for drilling the wire was inserted inside. By inserting a small-diameter jig into the powder to position the wire at a predetermined depth in the powder, retracting the jig leaving only the wire from that state, and then compressing and molding the powder It is characterized in that a molded body on which the wire protrudes is formed.

[0007]

According to the first aspect of the present invention, first, a cavity of a mold is filled with a powder of valve action metal, and then a guide hole for inserting a wire is formed in the powder with a suitable jig.
A wire is inserted into the guide hole to compress and embed the powder. Therefore, the wire can be easily and accurately embedded without applying an excessive force to the wire and without causing breakage or bending. The jig needs to be formed from a material having higher hardness and toughness than the wire. Then, by sintering the molded body in which the wire is embedded, a solid sintered body is obtained.

On the other hand, in the second invention, as described above, the powder is filled in the cavity of the molding die in the same manner as described above, and then a guide hole for a wire is formed in the powder by a jig. The jig is inserted into the powder while holding the wire in the cavity of the jig. As described above, since the wire is inserted into the powder while guiding it, the wire is inserted into the powder without being bent or bent. Thereafter, the jig is released after releasing the wire. Next, the powder is compressed by an upper mold having pores for avoiding the wire to form a compact, so that the wire is fixed to the compact while maintaining its soundness.

As described above, after the molded body having the wires protruded according to the first invention or the second invention is formed,
The compact may be sintered, and a dielectric film, a metal oxide film, and a conductive layer may be formed on the outer surface in that order. Note that these layers can be formed by a known method.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
The production method of the invention and the production method of the second invention will be described.

FIG. 1 is a process diagram showing one embodiment of a process for forming a sintered body in the manufacturing method of the first invention of the present application, and FIG.
FIG. 3 is a process diagram showing one embodiment of a process for forming a sintered body in the manufacturing method of the invention, FIG. 3 is a process diagram showing one embodiment of a process after the formation of the sintered body in the first invention or the second invention, and FIG. FIG. 3 is a cross-sectional view showing a state where an oxide film or the like is formed on the surface of the powder after sintering of the metal powder.

First, as shown in FIG. 1A, a metal powder 5 having a valve action, such as tantalum, aluminum, or niobium, is filled in a cavity 7 of a mold 6. This powder has a diameter of about 0.03 to 0.1 mm. The molding die 6 is composed of a middle die 8, a lower die 9 which can slide up and down in the middle die 8, and an upper die (see FIG. 1 (c)) 13 for compressing powder. The size of the cavity 7 is appropriately set according to the size of a solid electrolytic capacitor (hereinafter, referred to as a capacitor) to be manufactured. In this embodiment, the height is about 1 m
It is about 1 mm in width, about 1 mm in width, and about 1.5 mm in depth. It is pressed with an upper die and compression molded to a height of about 1 mm to form a molded article of about 1 mm square.

Next, as shown in FIG.
Is inserted into the powder 5 to form a guide hole 11 for inserting a wire 12 described later. Jig 10 Powder 5
It is preferable that the diameter of the portion 10a to be inserted therein (hereinafter, referred to as an insertion portion) is equal to or slightly larger than the diameter of the wire 12, but even if it is slightly smaller, the wire can be easily inserted and the object can be achieved. If the upper part of the insertion part 10a is formed thick as shown in the figure, the upper part of the guide hole 11 becomes tapered, and the wire 12 can be easily inserted. Also, guide hole 11
Can be arbitrarily set according to the insertion depth of the wire 12, but it is preferable that the depth is formed to be equal to or slightly smaller than the insertion depth of the wire 12. In this embodiment, the wire insertion length is
Since it is 0.6-0.7mm, it is 0.4mm. Jig 10
As the material of the insertion portion 10a, diamond having higher hardness and higher strength than the material of the wire 12 (for example, tantalum),
Cemented carbide, tungsten carbide or the like is used.

As shown in FIGS. 1 (c) and 1 (d), the powder 5 is compressed by pressing the upper mold 13 into which the wire 12 penetrates the center portion into the cavity 7, and the guide hole turns around. , The area around the wire 12 is filled with the powder, and the wire 12 can be held firmly. Although the wire 12 is held so as to slightly protrude from the lower end surface of the upper die 13, since the guide hole 11 is formed in the powder 5, the wire 12 can be inserted smoothly and bend or bend as in the related art. No. As described above, the compression of the powder 5 causes the upper mold 13
The portion of the wire 12 projecting from the lower end surface of the wire 5 is fixed in the powder 5.

Thereafter, as shown in FIG. 1E, the holding of the wire 12 is released, and the upper die 13 is removed while leaving the wire 12 at that position. Then, the wire 12 is cut and the lower mold 9 is pushed up to form a tantalum molded body with the wire 12.
14 ((f) of FIG. 1) is formed.

The following steps shown in FIG. 2 are used in place of the steps (FIGS. 1A to 1F) according to the above embodiment.
That is, the embodiment of the second invention may be adopted.

As shown in FIG. 2A, this step is the same as that of the above-described embodiment (FIG. 1A) until the cavity 7 of the mold 6 is filled with, for example, tantalum powder 5. is there.

Next, as shown in FIG.
A hole is made in the powder 5 with 15
The wire 12 is already held in the center of 15. jig
The insertion portion 15a of the powder 5 into the powder 5 is formed in a pipe shape,
A wire 12 is inserted and held in the cavity. Therefore, the wire 12 is inserted into the powder 5 while being guided by the insertion portion 15a of the jig. And, with the insertion of the insertion portion 15a,
The wire 12 is sent out from the tip of the insertion portion 15a and protrudes slightly longer (about 0.2 to 0.3 mm in this embodiment). With such a length, the wire 12 does not break or bend. The outer diameter of the insertion portion 15a of the jig is larger than the diameter of the insertion portion 10a (see FIGS. 1A and 1B) of the jig 10 in the above embodiment, and is about 0.5 to 0.6 mm. .

When the insertion portion 15a has been inserted, the portion of the powder 5 around the protruding tip of the wire 12 is removed.
Since the wire 12 is compacted by the tip of a, the wire 12 is supported in the powder.

Next, after cutting the wire 12 to a predetermined length, the jig 15 is removed as shown in FIG.

Next, as shown in FIG. 2D, the powder 5 is formed by an upper mold 17 having a hole 16 for avoiding the wire 12.
Compress and harden. At this time, the powder 5 is pushed out toward the guide hole, and the wire 12 is completely embedded in the powder. Thereafter, similar to the above-described embodiment, the upper mold 17 is retained while the wire 12 is left.
(See (e) of FIG. 2), cut the wire 12,
By pushing up the lower mold, a tantalum molded body with the wire 12 is formed (FIG. 2 (f)).

The steps after molding, that is, the step of manufacturing a capacitor using the above-mentioned molded body with a wire formed according to the embodiment of the first invention (FIG. 1) or the embodiment of the second invention (FIG. 2) are particularly required. The method is not limited, and a suitable method including a known method may be adopted.

An example of the manufacturing method will be described with reference to FIG.
First, as shown in FIG.
The sintered body 18 is formed by heating to 1400 ° C. and sintering. Next, as shown in FIG. 3B, a tantalum pentoxide (Ta ₂ O ₅ ) layer 21 is formed on the surface of each powder of the tantalum sintered body 14 and a part of the surface of the wire 12. Next, the tantalum sintered body 14 is impregnated with an aqueous solution of manganese nitrate and thermally decomposed (FIG. 3).
(C)), a first manganese dioxide layer 22 is formed on the tantalum pentoxide layer 21 on the surface of the powder, as shown in the sectional view of the tantalum powder 5 in FIG. Further, as shown in FIG. 3D, a second manganese dioxide layer 23 is formed around the sintered body. Next, as shown in FIG. 3E, the conductive paste 24 is applied to a part of the wire 12 to electrically connect the wire 12 and the second manganese dioxide layer 23. Then, as shown in FIG. 3 (f), the polypyrrole layer 27 as shown in FIG. 3 (g) is formed by performing electrolytic oxidation polymerization with the wire 12 plus and the tank 26 of the electrolytic solution 25 minus. Form. Polypyrrole layer 27
After the completion of the formation, the conductive paste 24 is removed as shown in FIG. The conductive paste 24 can be removed by a conventionally known process such as removal by plasma or peeling by tweezers. Next, as shown in FIG. 3 (i), a graphite layer 28 is formed, and a silver paste is applied to form a silver layer 29. The formation of the metal layer of these exteriors can be performed according to a method conventionally known as a method for manufacturing a solid electrolytic capacitor. The other electrode of the solid electrolytic capacitor is taken out of the silver layer.

As described above, the solid electrolytic capacitor is completed. Note that a protective film is formed on the surface of the silver layer 29 as necessary.

[0025]

According to the first and second aspects of the present invention, the wire for the electrode is prevented from being bent, broken or disconnected when the electrode wire is embedded in the valve metal powder and after the powder is formed. Further, uninsertion or incomplete insertion of the wire is eliminated, and the insertion operation is simplified, thereby improving the operation efficiency. In addition, even if the wire is slightly warped before insertion, it is possible to cope with the problem, the occurrence of defects due to the bending of the wire is reduced, the yield is improved, and the cost of the solid electrolytic capacitor is reduced.

Further, it is possible to prevent the occurrence of wire disconnection or the like in a later step or during use, so that the reliability is greatly improved.

[Brief description of the drawings]

FIG. 1 is a process chart showing one embodiment of a molded body forming step in the manufacturing method according to the first aspect of the present invention.

FIG. 2 is a process chart showing one embodiment of a molded body forming step in the manufacturing method according to the second aspect of the present invention.

FIG. 3 is a process chart showing one embodiment of a manufacturing process of the solid electrolytic capacitor after the formation of the molded body of FIG. 1 or 2;

FIG. 4 is a cross-sectional view showing a state in which an oxide film or the like is formed by a post-sintering process of the tantalum powder used in the manufacturing method of FIGS. 1 and 2;

FIG. 5 is a process chart showing an example of a conventional compact forming process.

[Explanation of symbols]

 5 Powder 6 Mold 11 Guide hole 12 Wire 14 Mold 15 Jig

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Claims (2)

(57) [Claims] 1. A solid electrolytic capacitor in which a molded body of a valve action metal on which an electrode wire is protruded is sintered, and a dielectric film, a metal oxide layer, and a conductor layer are formed on the outer surface thereof in this order. When forming the molded body, filling the mold metal with the valve action metal powder, drilling a guide hole into which the wire is to be inserted in the powder, the wire in the guide hole A method for manufacturing a solid electrolytic capacitor, comprising: forming a compact having wires protruded by compressing and compacting the powder after inserting the powder. 2. A solid electrolytic capacitor in which a molded body of a valve action metal on which an electrode wire is protruded is sintered, and a dielectric film, a metal oxide layer and a conductor layer are formed on the outer surface thereof in this order. In forming the compact, the valve metal powder is filled into a mold, and a wire is inserted into the powder by inserting a small-diameter jig for drilling into which the wire is inserted. It is characterized in that it is located at a predetermined depth in the powder, the jig is retracted while leaving only the wire from that state, and then the powder is compressed and formed to form a molded body on which the wire protrudes. Manufacturing method of solid electrolytic capacitor.