JP2001332449A - Anode for solid electrolytic capacitor, and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a solid electrolytic capacitor, which is made porous by sintering a valve-action metal powder, by which no molding die is necessary to be used, so that production cost can be easily im proved, no accident, such as manufacture of bent anode lead occurs, and no metallic powder is lost due to leakage or working environment which is not to be aggravated. SOLUTION: This manufacturing method includes a step for manufacturing a green sheet, in which a slurry containing a valve-action metal powder is used to form a green sheet and a step for winding the green sheet around a valve-action metal wire of the same kind as the valve-action metal forming the green sheet. Through the winding step, in which one end of the wire is in the outside area of the green sheet and the other end thereof is in the inside of the green sheet and the sintering step in which a wound body with a wire that is obtained by the winding step is sintered, a valve-action metal tantalum powder like a sheet is wound around a wire for anode lead and it is sintered to obtain a sintered body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anode body for a solid electrolytic capacitor and a method for manufacturing the same, and more particularly, to an anode body for a solid electrolytic capacitor obtained by sintering a powdered valve metal to make it porous. It relates to the manufacturing method.

[0002]

2. Description of the Related Art FIG. 4 (a) shows a perspective view of an anode body for a tantalum solid electrolytic capacitor which is an example of this kind of anode body. The anode body 10 shown in this figure is manufactured by a conventional manufacturing method, and is manufactured using a molding die. That is, the illustrated cylindrical tantalum anode body 1
First, as shown in FIG. 4 (b), first, as shown in FIG. 4 (b), a metal tantalum powder 21 is directly filled as it is into a cylindrical powder molding die 22, and a white outline is shown in the figure. As shown by the arrow, it is pressurized in the up-down direction to form a column. In this case, while pressing the tantalum powder 21, the tantalum wire 3 to be the anode lead is simultaneously implanted at the position of the central axis of the cylindrical press-formed body. After that, a columnar press-formed body on which the tantalum wire 3 is planted,
Vacuum sintering is performed at such a high temperature that the tantalum does not melt, such as 1400 to 1600 ° C., and the tantalum wire 3 is erected at the position of the center axis of the cylindrical sintered press-formed body 20 shown in FIG. The anode body 10 having the structure described above is obtained.

In order to obtain a capacitor from the above-described tantalum anode body 10, the anode body 10 is thereafter anodized to form a tantalum oxide dielectric material on the inner and outer surfaces of the sintered press-formed body 20. After forming a film and forming a cathode conductor layer including a layer of a conductive polymer or manganese dioxide, a graphite layer and a silver paste layer on the tantalum oxide film, a capacitor element is obtained.
Then, an external anode terminal and an external cathode terminal are attached to each of the above-mentioned cathode conductor layers, and further, the exterior is applied by, for example, a transfer molding method using a thermosetting epoxy resin as a material, thereby completing a tantalum solid electrolytic capacitor. The size and shape of the capacity of the completed capacitor are determined by the size of the powder molding die 22 and the molding conditions such as the pressing force when producing the anode body.

[0004] In the context of the present invention, the characteristic features of the conventional manufacturing method are that the tantalum powder is formed into a cylindrical shape by pressure molding using a metal mold, Then, while pressing and molding the tantalum powder,
At the same time, the tantalum wire 3 is implanted in the tantalum powder.

[0005]

As described above, a molding die is indispensable in the conventional method of manufacturing an anode body, and the capacitance value and the shape of the capacitor are used at the time of pressure molding of tantalum powder. It depends on the mold. That is, it is necessary to prepare a molding die for each type having different capacitance values and shapes of capacitors. For this reason, in the conventional manufacturing method, the more types of products to be produced, the higher the cost required for mold design and maintenance, and the need to exchange molds when switching between different types of products. For example, it is not easy to reduce the manufacturing cost.

Furthermore, since the powdered tantalum is directly pressed and molded as it is, when the tantalum powder 21 is filled into the cylinder of the mold 22, the powder may be spilled or scattered. This not only consumes raw materials wastefully, but also causes a deterioration in the working environment.

Further, since the wire 3 is implanted into the press-formed body while pressing and molding the tantalum powder, stress may be applied to the wire 3 and an accident such as bending of the wire 3 may occur. .

Therefore, the present invention does not require the use of a molding die in manufacturing a porous anode body for a solid electrolytic capacitor obtained by sintering a valve metal powder to make it porous. It is intended to be easy and free from accidents such as bending of the lead wire for the anode lead, and to avoid wasting or deteriorating the working environment due to metal powder spilling out of the mold. It is.

[0009]

An anode body for a solid electrolytic capacitor according to the present invention comprises a sintered roll obtained by winding and sintering a green sheet obtained from a slurry containing a powder of valve action metal; An anode lead that is a core of the sintered roll,
An anode lead made of the same kind of valve action metal as the sintered winding body and projecting from the inside of the sintered winding body to the outside in one direction of the central axis of the sintered winding body; Have.

[0010] The anode body for a solid electrolytic capacitor described above comprises:
A green sheet forming step of forming a green sheet from a slurry containing powder of a valve action metal, and a step of winding the green sheet around a wire of the same type of valve action metal as the valve action metal forming the green sheet A winding step of winding the wire such that one end of the wire is located in an area outside the green sheet and the other end is located in an area inside the green sheet, and the wire obtained in the winding step And a sintering step of sintering the wound body with the seal.

[0011]

Next, embodiments of the present invention will be described. Referring to FIG. 1A which shows a perspective view of an anode body for a tantalum solid electrolytic capacitor according to a first embodiment of the present invention, an anode body 1 according to the present invention has a tantalum wire 3 wound around a core. 4A is different from the conventional anode body 10 shown in FIG. The anode body according to the present embodiment is manufactured as follows. First, a slurry is prepared by appropriately mixing tantalum powder, an organic solvent, and a binder. Next, the slurry obtained as described above is applied as a thin film on a resin film using a doctor blade method or the like to form a rectangular green sheet.

Next, a tantalum wire 3 to be an anode lead is placed on the green sheet 4. At this time, as shown in FIG. 1B, the wire 3 is made to extend along one short side of the green sheet 4, one end of the wire 3 is protruded from the green sheet 4, and the other end is connected to the green sheet 4. 4 inside. Then, the above-described tantalum wire 3 is used as a winding core, and is wound in the longitudinal direction of the rectangular green sheet as indicated by a thick arrow in the drawing.

Thereafter, the (unsintered) winding body with the tantalum wire obtained as described above is heated to remove the binder and the organic solvent, and further sintered in a vacuum to obtain a structure shown in FIG. )
An anode body 1 comprising a tantalum wire 3 and a sintered wound body 2 having the same as a core is obtained as shown in FIG.

According to the present embodiment, since the tantalum powder is not used directly and is in the form of a slurry, unlike the conventional production method, when the powder is filled into a molding die, the powder is wasted or the work is not performed. It does not degrade the environment. Moreover, the size of the capacitor when it is made can be easily changed by cutting the green sheet into an appropriate size or by increasing or decreasing the number of windings. Easy to do. Further, since a mold is not used, the cost required for its design and maintenance is unnecessary. Furthermore, by winding the tantalum wire 3 around the core,
Since a force is applied to the wire 3 from the periphery toward the center, the wire does not bend, and the pull-out strength is improved as compared with the related art.

According to the present invention, the following embodiments can further improve the productivity. That is, with reference to FIG. 2 showing a winding method in the manufacturing method according to the second embodiment, in the present embodiment, two tantalum wires 3A and 3B are used for a core, and these two tantalum wires 3A and 3B are used.
The two wires are arranged along one side of the green sheet 4, one wire 3A is arranged so as to protrude upward from the green sheet, and the other wire 3B is arranged as shown in FIG. Arrange so that it protrudes downward.
And on the green sheet, two wires 3A, 3
B are coaxial and face each other with a space between them.

Next, as shown by a thick arrow in FIG. 2A, the green sheet 4 is wound around the two wires 3A and 3B as a core. Thereafter, as shown in FIG. 2B, the unsintered wound body 5 with the tantalum wire is cut at a position between the two wires 3A and 3B on a plane perpendicular to the center axis of the wound body. I do.

According to the present embodiment, two anode bodies can be manufactured only once through a series of manufacturing steps. That is,
Productivity can be improved about twice. Also, by changing the length of the portion of the tantalum wires 3A and 3B inside the winding body and changing the cutting position of the winding body according to the difference in the length, two operations having different capacities can be performed in one operation. An anode body can be manufactured.

The second embodiment can be modified as in the third embodiment described below. That is, with reference to FIG. 3 showing a winding method in the manufacturing method according to the third embodiment, in the present embodiment, one tantalum wire 3C is used for the core. However, unlike the first embodiment, both ends of the wire 3C have a length protruding from the green sheet 4. Then, the tantalum wire 3C is placed on the green sheet 4 along one short side as shown in FIG. 3 (a), and the wire 3C is wound around the core as shown by the thick arrow in FIG. And roll the green sheet 4.

Thereafter, as shown in FIG. 3B, the obtained unsintered wound body 5 with a wire is cut along a plane perpendicular to the central axis of the wound body. In this way, two anode bodies can be obtained by one series of operations. Of course, if the cutting position is changed, two anode bodies having different capacities can be manufactured at once. According to the present embodiment, since only one core is required, the winding is easier than in the second embodiment, and the work efficiency can be improved accordingly.

[0020]

As described above, according to the present invention,
When manufacturing anode bodies for solid electrolytic capacitors made by sintering powder of valve action metal to make them porous, there is no need to use a molding die, so production costs can be easily improved, and wires for anode leads can be easily manufactured. There is no accident such as bending, and it is possible to prevent useless use of metal powder and deterioration of the working environment.

[Brief description of the drawings]

FIG. 1 is a perspective view of an anode body according to a first embodiment of the present invention and a diagram showing a winding method.

FIGS. 2A and 2B are a plan view and a transparent side view showing a winding method according to a second embodiment of the present invention. FIGS.

FIGS. 3A and 3B are a plan view and a perspective side view showing a winding method according to a third embodiment of the present invention. FIGS.

FIG. 4 is a perspective view of an anode body manufactured by a conventional method, and a cross-sectional view schematically showing a molding method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode body 2 Sintered winding body 3, 3A, 3B, 3C Tantalum wire 4 Green sheet 5 Unsintered winding body 10 Anode body 20 Sintered press molded body 21 Tantalum powder 22 Molding mold

Claims (9)

[Claims] 1. A sintered roll obtained by winding and sintering a green sheet obtained from a slurry containing powder of valve action metal, and an anode lead as a core of the sintered roll. An anode lead made of the same type of valve action metal as the sintering winding body and projecting from the inside of the sintering winding body to the outside in one direction of the central axis of the sintering winding body; An anode body for a solid electrolytic capacitor comprising: 2. The anode body for a solid electrolytic capacitor according to claim 1, wherein a length of a portion of the anode lead inside the sintered winding body is in a direction of a center axis of the sintered winding body. An anode body for a solid electrolytic capacitor, wherein the anode body is shorter than the length. 3. The anode body for a solid electrolytic capacitor according to claim 1, wherein a length of a portion of the anode lead inside the sintered body is in a direction of a central axis of the sintered body. An anode body for a solid electrolytic capacitor characterized by being the same in length. 4. A green sheet forming step of forming a green sheet from a slurry containing powder of a valve action metal, wherein the green sheet is formed by winding a wire of the same type of valve action metal as the valve action metal forming the green sheet. A winding step of arranging and winding the wire so that one end of the wire is located outside the green sheet and the other end is located inside the green sheet. And a sintering step of sintering the wire-wound body obtained in the step. 5. The method for manufacturing an anode body for a solid electrolytic capacitor according to claim 4, wherein, in the winding step, a length of a part of the wire serving as a core in an area inside a green sheet is green. A method for producing an anode body for a solid electrolytic capacitor, comprising using a wire shorter than a length of a sheet winding in a central axis direction. 6. The method for manufacturing an anode body for a solid electrolytic capacitor according to claim 5, wherein, in the winding step, a length of a portion of each of the wires serving as the cores in a region inside a green sheet is set. The first wire and the second wire are used by using first and second two wires shorter than the length of the green sheet in the direction of the central axis.
And the wires are arranged on the central axis of the winding so that they do not abut each other and protrude from the green sheet in opposite directions, and between the winding step and the sintering step, The winding body with the first and second wires obtained in the winding step is a part of the center axis of the winding body between the first wire and the second wire facing each other. A method for producing an anode body for a solid electrolytic capacitor, comprising a step of cutting at a plane perpendicular to the anode. 7. The method for manufacturing an anode body for a solid electrolytic capacitor according to claim 6, wherein: a length of a portion of the first wire in a region inside the green sheet; A method for manufacturing an anode body for a solid electrolytic capacitor, wherein the length of a portion in an internal region is different. 8. A green sheet forming step of forming a green sheet from a slurry containing powder of a valve action metal, wherein the green sheet is formed by winding a wire of the same type of valve action metal as the valve action metal forming the green sheet. A winding step, wherein the wire is arranged and wound so that both ends of the wire protrude in opposite directions to an area outside the green sheet, and a wire with the wire obtained in the winding step is provided. For a solid electrolytic capacitor, comprising: a cutting step of cutting the wound body of the above at a plane perpendicular to the center axis of the wound body; and a sintering step of sintering each of the wound bodies with wires obtained by cutting. Manufacturing method of anode body. 9. The method for manufacturing an anode body for a solid electrolytic capacitor according to claim 8, wherein, in the cutting step, the lengths of the two wound bodies with wires after cutting are different from each other in the central axis direction. A method for producing an anode body for a solid electrolytic capacitor, comprising cutting.