JPH08288183A - Structure of capacitor element in solid electrolytic capacitor and its manufacture - Google Patents

Abstract

PURPOSE: To positively join an anode wire to a chip piece without increasing material cost and reducing the effective volume in the chip piece of a capacitor element in a solid electrolytic capacitor such as tantalum. CONSTITUTION: The tip of an anode wire 13 is electrically joined to a chip piece 12 by a nail head which is formed by crushing a ball part 13" formed at the tip.

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 capacitor element used for a solid electrolytic capacitor such as a tantalum solid electrolytic capacitor or an aluminum solid electrolytic capacitor, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, a capacitor element used for this type of solid electrolytic capacitor is constructed as shown in FIGS. That is, this capacitor element 1
Is a metal powder such as tantalum, which is applied to the porous chip piece 2,
Anode wire 3 made of metal such as tantalum in the chip piece 2
Is formed by embedding a part of it, and then sintered at a high temperature.

The chip piece 2 of this capacitor element 1 is immersed in a chemical conversion solution such as an aqueous solution of phosphoric acid, and a direct current is applied between the anode wire 3 protruding from the chip piece 2 and the chemical conversion solution. As shown in FIG. 12, the surface of each metal powder in the chip piece 2 and the root of the anode wire 3 are
By forming a dielectric film 4 of tantalum pentoxide or the like, then dipping the chip piece 2 in an aqueous solution of manganese nitrate, and then lifting and baking the chip piece 2 repeatedly, as shown in FIG. 14 is formed, and further, a metal film such as silver or nickel is formed on the surface of the solid electrolyte film 5 by using a graphite film as a base on the surface of the solid electrolyte film 5, as shown in FIG. A cathode film 6 made of a solid electrolyte film 5, a graphite film, and a metal film is formed on the entire surface of the surface except one end surface where the anode wire 3 projects.

Further, as shown in FIG. 15, this capacitor element 1 is provided with a pair of left and right lead terminals 7, 8 by welding the anode wire 3 of the capacitor element 1 to one lead terminal 7 or the like. It is fixed so that the other lead terminal 8 is connected to the cathode film 6 of the chip piece 2,
A solid electrolytic capacitor is constructed by packaging the whole of these in a mold part 9 made of synthetic resin.

[0005]

As described above, the conventional capacitor element 1 has a structure in which a part of the anode wire 3 protruding from one end surface of the chip piece 2 is embedded in the chip piece 2. Therefore, the volume of the tip piece 2 in the metal powder, that is, the effective volume of the tip piece 2 is reduced by the amount of the anode wire 3 embedded in the tip piece 2.

Moreover, the chip piece 2 in the anode wire 3
The stress is likely to be concentrated in the root portion with respect to the one end surface of the base material, and the base material is bent and deformed easily. Due to the bending deformation, the dielectric film 4 formed in the base portion is cracked and its insulating property is destroyed. . Therefore, in the conventional capacitor element 1, since the wire diameter D of the anode wire 3 is increased to some extent to prevent dielectric breakdown at the root portion of the anode wire 3, The reduction rate of the effective volume of the chip piece 2 generated by embedding it in the chip piece 2 is large, which not only prevents the solid electrolytic capacitor from becoming small and having a large capacity, but also the anode wire 3 having a thick wire diameter D. However, there is a problem in that the material cost is increased and the manufacturing cost of the capacitor element is increased due to the use of.

It is a technical object of the present invention to provide a structure of a capacitor element which solves these problems and a manufacturing method thereof.

[0008]

In order to achieve this technical object, the structure of the capacitor element in the present invention is as follows: "Solid electrolysis consisting of a chip piece obtained by sintering metal powder and an anode wire protruding from this chip piece. In the capacitor element for capacitors, the tip of the anode wire is electrically joined to the chip piece by a nail head formed by crushing a ball portion formed at the tip. "

Further, the method of manufacturing a capacitor element according to the present invention comprises "a step of solidifying and forming a metal powder into a chip piece and a step of sintering the chip piece at a high temperature,
Further, at the tip of the anode wire inserted into the movable capillary tool, a step of heating and melting to form a ball portion, and this ball portion is moved by moving the capillary tool.
It is characterized in that it includes a step of press-bonding to the chip piece after the solidification or sintering and a step of cutting the anode wire into an appropriate length. "

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 8 show a first embodiment. In this figure, reference numeral 12 represents a chip piece obtained by solidifying and forming metal powder such as tantalum and then heating it to a temperature of 400 to 700 ° C. to remove the binder.
As shown in FIG. 1, the chip piece 12 is placed in the heater block A in a box B in which the bottom plate is formed in the heater block A.
Box B is loaded while touching the upper surface of
In an inert gas such as argon gas or nitrogen gas,
Alternatively, an oxygen-free gas such as a redox gas in which a maximum of about 5% hydrogen gas is mixed with this inert gas is continuously supplied from the supply port C by an appropriate amount, and then this oxygen-free gas is supplied to the box B. By being configured so as to eject upward from the opening hole D formed in the upper surface, an atmosphere of oxygen-free gas is formed in the vicinity of the vertically movable capillary tool E arranged above the opening hole D.

On the other hand, reference numeral 13 'indicates an anode wire material made of various metal wires such as tantalum wire, niobium wire, aluminum wire or copper wire coated with aluminum,
The anode wire material 13 'is subjected to a reduction treatment in which it is passed through an oxidation-reduction furnace in which an atmosphere of an oxidation-reduction gas is heated in advance to remove the oxide film on the surface thereof, and then the inside of the capillary tool E is By sequentially inserting the anode wire material 13 ′ downward, the lower end of the anode wire material 13 ′ protruding from the capillary tool E is melted by an electric spark between the lower end and the spark torch body F, so that The ball portion 13 ″ is formed.
The spark torch body F retreats from the portion immediately below the capillary tool E immediately after forming the ball portion 13 ″.

Next, the above-mentioned capillary tool E is shown in FIG.
As shown in FIG. 2, the ball portion 13 ″ formed at the lower end of the anode wire material 13 ′ is crushed in the axial direction of the anode wire material 13 ′ by moving downward toward the tip piece 12. In the form of a head, it is joined to one end surface of the chip piece 12.

By the way, the anode wire material 13 'is
Before being fed into the capillary tool E, the oxide film on the surface of the chip piece 1 is removed by passing through the oxidation-reduction furnace as described above.
It is possible to improve the certainty of joining to No. 2. Also,
By forming the ball portion 13 ″ on the lower end of the anode wire material 13 ′ by heating and melting in the atmosphere of the non-oxidizing gas ejected from the opening D as described above,
Since it is possible to prevent an oxide film from being generated on the surface of the ball portion 13 ″ when the ball portion 13 ″ is formed by heating and melting, it is possible to further improve the reliability of bonding to the chip piece 12, and further, the anode wire. As described above, the series of steps from the formation of the ball portion 13 ″ by heating and melting to the lower end of the material 13 ′ to the pressure joining of the ball portion 13 ″ to the chip piece 12 is performed by using the non-oxidizing gas ejected from the opening D By performing the operation in an atmosphere, the ball portion 1 ″ is formed when the ball portion 13 ″ is formed by heating and melting, and before the pressing and joining to the chip piece.
Since it can prevent the oxide film from being generated on the surface of 3 ",
The certainty of joining to the chip piece 12 can be greatly improved.

In this case, the oxygen-free gas is, as described above, an inert gas such as argon gas or nitrogen gas, or an oxidation gas obtained by mixing this inert gas with hydrogen gas at a maximum of about 5%. It is preferable to use a reducing gas, but when nitrogen gas is used, a nitrogen compound may be generated on the surfaces of the tantalum anode wire material 13 'and the ball portion 13 ". It is particularly preferable to use less oxygen or to use oxygen-free gas excluding nitrogen gas.

When the anode wire material 13 'is bonded to the one end surface of the chip piece 12 in this manner, the capillary tool E is moved upward as shown in FIG. The anode wire 13 joined to the chip piece 12 is cut from the anode wire material 13 'by cutting with a cutter means G such as scissors in the middle of the portion protruding from the capillary tool E, as shown in FIG. Separate it.

As a result, as shown in FIG. 8, the tip of the anode wire 13 is attached to the one end face of the chip piece 12, and the ball portion 13 ″ formed at the tip is attached to the anode wire 1.
The anode wire 1 can be electrically connected by a nail head formed by crushing in the axial direction of 3
The strength of the root portion of the chip piece 12 of No. 3 can be significantly increased without increasing the wire diameter of the anode wire 13.

In this case, the lower end of the insertion hole E1 of the anode wire material 13 'in the capillary tool E is
As shown in FIG. 6, by forming it in the insertion hole E2 having a large diameter D0, the connection portion of the anode wire 13 joined to the chip piece 12 to the ball portion 13 ″ is partially made large in diameter D0. Therefore, the strength of the root portion of the anode wire 13 can be further increased.

The capacitor element 11 has about 1
After the chip pieces 12 are sintered by heating to a high temperature of 200 to 1500 ° C., thereafter, a dielectric film such as tantalum pentoxide is formed by anodic oxidation by the same method as the above-mentioned conventional method, and manganese nitrate. Formation of the solid electrolyte membrane 5 of manganese dioxide or the like by repeating soaking in an aqueous solution, then withdrawing and firing a plurality of times,
Further, the cathode film 6 is formed by forming a metal film such as silver or nickel on the graphite film as a base.

The tip piece 12 of the anode wire 13
The chip piece 12 is joined to about 1200 to 1500
It may be performed after performing the sintering of heating to a high temperature of ° C. In addition, Cabilly Tool E
At the time of forming the ball portion 13 ″ by heating and melting the lower end of the anode wire material 13 ′ inserted in the above, the lower end of the anode wire material 13 ′ is changed to the lower end as in the embodiment. Instead of melting by the electric spark generated between the spark torch body F and FIG.
As shown in FIG. 5, the lower end of the anode wire material 13 ′ inserted through the capillary tool E is heated and melted by irradiating the laser beam from the laser beam emitting device H, or tantalum, niobium, aluminum or copper is used. May be heated and melted by a gas flame having a high temperature that melts, that is, a gas flame that generates a temperature higher than the melting point of the anode wire material 13 '.

Furthermore, as shown in FIG. 8, the ball portion 1
After pressing the 3 ″ to the chip piece 12,
A laser beam is emitted from the laser beam emitting device H to the ball portion 13 ″ to weld the ball portion 13 ″ to the chip 12
It is possible to increase the bonding strength with respect to. In addition, prior to joining the anode wire 13 to the tip piece 12, the tip piece 12 is heated to a temperature of about 400 ° C. in an oxidation-reduction gas atmosphere in the same manner as the anode wire material 13 ′. By adding a redox treatment step of removing the oxide film on the surface, the certainty and strength of joining the anode wire 13 to the chip piece 12 can be further improved. The redox treatment step for the chip piece 12 may be performed in the box B in the above-described embodiment, or the box B may be formed in a tunnel type, and the chip piece 12 may be formed along the tunnel. It may be performed during the transfer of the. In this embodiment, the ball portion 1
3 "is crushed in the axial direction of the anode wire 13,
Not limited to this, for example, a nail formed by lowering the capillary tool from the obliquely upward direction with respect to the tip piece and crushing the tip of the anode wire with the ball portion formed at the tip from the obliquely upward direction. It is also possible to adopt a structure and method in which, after electrically connecting to the chip piece with the head, the capillary tool is moved upward in a direction different from the above oblique direction (for example, various directions such as gravity direction are possible). is there.

[0021]

According to the present invention, as in the present invention, the tip of the anode wire is electrically connected to the chip piece by a nail head formed by crushing the ball portion formed at the tip in the axial direction of the anode wire. By connecting, it is possible to significantly increase the strength of the root of the anode wire to the chip piece,
Since the wire diameter of the anode wire can be made thinner than in the conventional case, the material cost of the anode wire can be reduced, the manufacturing cost can be reduced, and the effective volume of the chip piece can be prevented from being reduced. Therefore, it is possible to surely achieve miniaturization and large capacity in the solid electrolytic capacitor.

In particular, according to the method of the present invention, the anode wire can be continuously bonded to the chip piece, and the anode wire made of a material different from that of the chip piece can be bonded to the chip piece. Therefore, there is an effect that the cost can be further reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a first state according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a second state according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a third state according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a fourth state according to the first embodiment of the present invention.

FIG. 5 is a diagram showing a fifth state according to the first embodiment of the present invention.

FIG. 6 is an enlarged sectional view of a main part of the capillary tool according to the first embodiment.

FIG. 7 is an enlarged cross-sectional view showing a joined state by the capillary tool of FIG.

FIG. 8 is a front view of a capacitor element according to the present invention.

FIG. 9 is a diagram showing a second embodiment of the present invention.

FIG. 10 is a perspective view of a conventional capacitor element.

FIG. 11 is a vertical sectional front view of a conventional capacitor element.

FIG. 12 is a vertical sectional front view showing a state where a dielectric film is formed on a chip piece in a conventional capacitor element.

FIG. 13 is a vertical cross-sectional front view showing a state in which a solid electrolyte membrane is formed on a chip piece of a conventional capacitor element.

FIG. 14 is a vertical cross-sectional front view of a conventional capacitor element in which a cathode film is formed on a chip piece.

FIG. 15 is a vertical cross-sectional front view of a solid electrolytic capacitor using a capacitor element.

[Explanation of symbols]

 11 Capacitor element 12 Chip piece 13 Anode wire 13 'Anode wire material 13 "Ball part A Heater block B Box C Oxygen-free gas supply port D Oxygen-free gas ejection opening E Capillary tool F Spark torch body G Cutter means H Laser Beam launcher

Claims (7)

[Claims] 1. A capacitor element for a solid electrolytic capacitor comprising a chip piece obtained by sintering metal powder and an anode wire protruding from the chip piece, wherein the tip of the anode wire is the tip of the tip wire with respect to the tip piece. A structure of a capacitor element in a solid electrolytic capacitor, characterized in that a ball head formed in the above is crushed and electrically connected by a nail head. 2. The tip of the anode wire is electrically joined to the chip piece by a nail head formed by crushing a ball portion formed at the tip in the axial direction of the anode wire. The structure of the capacitor element in the solid electrolytic capacitor according to claim 1. 3. A step of solidifying and forming metal powder into a chip piece, and a step of sintering the chip piece at a high temperature,
Further, at the tip of the anode wire inserted into the movable capillary tool, a step of heating and melting to form a ball portion, and this ball portion is moved by moving the capillary tool.
A method of manufacturing a capacitor element in a solid electrolytic capacitor, comprising: a step of pressure-bonding to the chip piece after the solidification or sintering and a step of cutting the anode wire into an appropriate length. 4. The method according to claim 3, wherein the step of forming the ball portion for the tip of the anode wire is performed in an atmosphere of an oxygen-free gas such as an inert gas or a redox gas.
A method for manufacturing a capacitor element in the solid electrolytic capacitor described in 1. 5. A series of steps from the formation of the ball portion to the tip of the anode wire to the pressure bonding of the ball portion to the chip piece are performed in an atmosphere of an oxygen-free gas such as an inert gas or a redox gas. The method for manufacturing a capacitor element in a solid electrolytic capacitor according to claim 3, characterized in that 6. The method for manufacturing a capacitor element in a solid electrolytic capacitor according to claim 3, wherein the anode wire is subjected to an oxidation-reduction treatment before the ball portion is press-bonded to the chip piece. 7. The method for manufacturing a capacitor element in a solid electrolytic capacitor according to claim 3, wherein the chip piece is subjected to an oxidation-reduction treatment before the ball portion is pressure-bonded to the chip piece.