JPH11251189A - Manufacture of capacitor element in solid-state electrolytic capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To raise impedance characteristic and reduce a manufacturing cost by welding an anode plate to a tip of an anode bar, applying synthetic resin to a part between one edge face of a chip piece of an anode bar and an anode plate and thereafter forming a dielectric film, solid-state electrolytic layer and a cathode film in a chip piece. SOLUTION: After a chip piece 22 is mounted vertically so that a tip surface of an anode bar 23 projecting from one edge face 22a comes into contact with each anode plate 27 of a lead frame E, the anode bar 23 is welded to the anode plate 27. Then, synthetic resin 28 such as epoxy resin is applied to a part between the one edge face 22a of the chip piece 22 of the anode bar 23 of each chip piece 22 and the anode plate 27. Each chip piece 22 fixed to the lead frame E is subjected to anode oxidation together with the lead frame E and a dielectric film 24 is formed in a surface of metallic powder of each chip 22. After a solid-state electrolytic layer 25 is formed on the dielectric film 24, a cathode film 26 is formed in a surface of the solid-state electrolytic layer 25.

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 capacitor element used for a solid electrolytic capacitor using a valve metal such as tantalum or aluminum.

[0002]

2. Description of the Related Art Generally, in manufacturing a capacitor element used for a solid electrolytic capacitor, the following method is employed as is well known in the art.
That is, first, as shown in FIG. 15, when a powder of valve metal such as tantalum is solidified and formed into a porous chip piece 2, a metal anode rod 3 is attached to the chip piece 2, 3 so as to protrude from one end face 2a, and then, as shown in FIG.
Is partially immersed in a chemical conversion solution B such as a phosphoric acid aqueous solution placed in a treatment tank A, and then subjected to anodic oxidation in which a direct current is applied between the mixture and the chemical conversion solution B. On the surface of the powder and a part of the surface of the anode rod 3,
A dielectric film 4 such as tantalum pentoxide is formed.

Next, as shown in FIG. 17, the chip piece 2 is immersed in an aqueous solution of manganese nitrate D placed in a processing tank C up to one end face 2a of the chip piece 2, then pulled up and dried and fired. By repeating this a plurality of times, the solid electrolyte layer 5 made of a metal oxide such as manganese dioxide is formed only on the chip piece 2 on the surface of the dielectric film 4, and as shown in FIG. On the surface of the solid electrolyte layer 5, a method of forming a cathode film 6 composed of a graphite layer and a metal layer of nickel or the like to form the capacitor element 1 is adopted.

Further, the formation of the graphite layer and the metal layer in the anode film 6 is performed by immersing the chip piece 2 in a solution containing graphite and a plating solution up to one end surface 2a.

[0005]

In this conventional manufacturing method, a dielectric film 4 between an anode bar 3 and a cathode film 6 is formed.
In order to ensure the electrical insulation by the solid electrolyte layer 5
And the cathode film 6 must not be formed on one end surface 2a of the chip piece 2. For this purpose, the solid electrolyte layer 5 and the cathode film 6 are immersed in the chip piece 2 in various treatment liquids. In the formation by this, the liquid level of each processing liquid must be strictly regulated so that the liquid level of the processing liquid does not exceed the one end surface 2a of the chip 2, so that a lot of trouble is required. In addition to the necessity, the liquid level frequently exceeds the one end face 2a and the occurrence rate of defective products is high, so that the manufacturing cost of the capacitor element is greatly increased.

In order to make a solid electrolytic capacitor using the capacitor element 1 having the above-described structure, as shown in FIG.
After the anode plate 7 extending in parallel with the anode bar 3 is fixed by welding, the entire capacitor element 1 is exposed to the surface of the package body 8 with a package 8 made of synthetic resin. In this configuration, a cathode piece 9 electrically connected to the cathode film 6 of the capacitor element 1 is formed on one end surface of the package body 8, or as shown in FIG. Capacitor element 1
Is fixed between the anode lead terminal 10 and the cathode lead terminal 11 by welding the anode rod 3 of the capacitor element 1 to the anode lead terminal 10, and the cathode film 6 is attached to the cathode lead terminal 11. The capacitor element 1 is arranged so as to be electrically connected to the capacitor element 1, and the entire capacitor element 1 is sealed with a package 12 made of synthetic resin.

In this case, conventionally, after the capacitor element 1 is manufactured by the above-described method, the anode plate 7 is fixed to the anode rod 3 of the capacitor element 1 by welding as shown in FIG. Or Figure 2
As shown in FIG. 0, the anode lead terminal 10 is fixed by welding. However, during this welding, thermal damage to the dielectric film 4, the solid electrolyte layer 5, and the cathode film 6 in the capacitor element 1 is reduced. In order to reduce the length, the projection length L from the one end face 2a of the chip piece 2 to the anode plate 7 or the anode-side lead terminal 10 of the anode rod 3 must be considerably increased. Since the welding margin S for the anode plate 7 or the anode-side lead terminal 10 is required, the length of the capacitor element is greatly increased by the amount of the welding margin S in addition to the length of the protrusion L. As a result, the solid electrolytic capacitor using this capacitor element not only becomes larger in its entirety, but also increases in weight, and furthermore, the solid state capacitor becomes larger due to the significantly increased length of the capacitor element. Ratio of the volume of the capacitor element occupying the volume of the package body is decreased in solution capacitors, in Pitan scan characteristics there is a problem that the decrease.

An object of the present invention is to provide a manufacturing method which solves these problems.

[0009]

In order to achieve this technical object, a first aspect of the present invention is to provide at least one of a porous chip piece, a valve metal powder, and an anode rod having one end face on the chip piece. A step of compacting so as to protrude from
A step of welding an anode plate to the tip of the anode rod, and a step of forming at least a dielectric film, a solid electrolyte layer and a cathode film on the chip piece; After a step of welding the anode plate to the anode bar, after adding a step of applying a synthetic resin to a portion between one end surface of the chip piece and the anode plate of the anode rod, a dielectric material is applied to the chip piece. The process is characterized by shifting to a step of forming a membrane, a solid electrolyte layer and a cathode membrane. Is the thing.

According to a second aspect of the present invention, there is provided a method as set forth in the first aspect, wherein the anode plate is a flat plate perpendicular to the axis of the anode rod, and the anode rod is brought into contact with the tip surface thereof. It is characterized by welding. " Still further, claim 3 of the present invention provides a method as set forth in claim 1, wherein before and after the step of applying a synthetic resin to a portion of the anode rod between one end surface of the chip piece and the anode plate, It is characterized in that an insulating film is formed on the anode plate, a step of forming a dielectric film on at least the chip piece, and then a step of removing the insulating film on the anode body is added. " Things.

[0011]

According to the present invention, as described above, after the anode plate is welded to the tip of the anode rod projecting from the chip piece of the capacitor element, the dielectric piece is applied to the chip piece in the capacitor element. By forming a membrane, a solid electrolyte layer and a cathode film, after forming a dielectric film, a solid electrolyte layer and a cathode film on a chip piece, welding an anode plate to an anode rod protruding from the chip piece Then, as in the conventional case, the dielectric film, the solid electrolyte layer and the cathode film in the chip piece can be completely eliminated from being thermally damaged when the welding is performed.
The protruding length of the anode bar from one end face of the chip piece to the anode plate can be greatly reduced.

Further, as described above, according to the present invention, after the synthetic resin is applied to a portion between one end surface of the chip piece and the anode plate in the anode bar in the capacitor element, the chip in the capacitor element is formed. By forming the dielectric film, the solid electrolyte layer and the cathode film on the piece, the solid electrolyte layer and the cathode film formed on the chip piece are electrically connected to the anode bar and the metal powder on the chip piece. Since this can be reliably prevented by the synthetic resin applied to the anode bar, when the solid electrolyte layer and the cathode film are formed by immersing the chip pieces in the processing liquid, the liquid level of the processing liquid is reduced. This does not require strict regulation as in the prior art, and the solid electrolyte layer is formed as an organic semiconductor layer by a chemical polymerization method or an electrolytic oxidation polymerization method. It can be formed.

Therefore, according to the present invention, since the length of the capacitor element can be greatly reduced, the size and weight of the solid electrolytic capacitor using the capacitor element can be reliably reduced, and the capacitor element occupying the whole volume can be achieved. The volume ratio of the capacitor element can be increased, and the impedance characteristics can be improved.In addition, the productivity of the capacitor element can be improved, and the occurrence rate of defective products can be reduced, so that the manufacturing cost can be significantly reduced. Has an effect that can be.

In particular, as described in claim 2, the anode plate is a flat plate perpendicular to the axis of the anode bar, and the anode bar is welded to the anode plate by contacting the tip end surface thereof. Since it is possible to avoid adding the welding allowance of the anode plate to the anode bar to the length of the element as in the related art, and to further reduce the length of the capacitor element, the above-described effect can be further promoted. is there.

Further, as set forth in claim 3, before and after the step of applying a synthetic resin to a portion of the anode bar between one end surface of the chip piece and the anode plate, the anode plate may be applied to the anode plate. Forming an insulating coating, and then adding a step of removing the insulating coating on the anode body after passing through a step of forming a dielectric film on at least the chip piece, thereby making the anode plate a metal on the chip piece. It does not need to be made of valve metal with the same material as powder and anode rod. It is made of copper or copper alloy or carbon steel, or aluminum when metal powder and anode rod of chip piece are tantalum. Since the metal can be made cheaper, the manufacturing cost can be further reduced.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. 1 to 6, reference numeral 22 denotes a chip piece formed by compacting a powder of a valve action metal such as tantalum into a porous cube as in the conventional case. ,
When the metal powder in the chip piece 22 is tantalum, the same anode rod 23 made of tantalum is embedded so that the anode rod 23 protrudes from one end face 22 a of the chip piece 22.

1 to 9, reference symbol E denotes a lead frame stamped from a metal plate made of a valve metal such as tantalum. The lead frame E has an anode plate 27 formed in a planar shape. They are integrally formed at appropriate pitch intervals along the longitudinal direction. Then, while the lead frame E is being transported in the longitudinal direction, the chip piece 22 is attached to each anode plate 27 of the lead frame E as shown in FIGS. After the anode rod 23 protruding from the one end face 22 a is placed vertically so as to be in contact with the end face, the anode rod 23 is welded to the anode plate 27.

This welding is performed by laser welding, in which a contact portion between the anode bar 23 and the anode plate 27 is irradiated with a laser beam, or a high current is applied between the anode bar 23 and the anode plate 27. This is performed by resistance welding or the like. Next, among the anode rods 23 in each of the chip pieces 22,
As shown in FIG. 3, a synthetic resin 2 such as an epoxy resin is provided on a portion between one end face 22a of the chip piece 22 and the anode plate 27.
8 is applied.

Then, each chip piece 22 fixed to the lead frame E is immersed together with the lead frame E in a chemical solution such as a phosphoric acid aqueous solution, and then a direct current is applied between the chip piece 22 and the chemical solution. 4 is applied, a dielectric film 24 such as tantalum pentoxide is formed on the surface of the metal powder in the chip piece 22 and the surface of the lead frame E, as shown in FIG. As shown in FIG. 5, the dielectric film such as tantalum pentoxide on the surface of the anode plate 27 (the surface opposite to the chip side 22) in the lead frame E is peeled and removed by polishing or the like.
The removal operation is performed by the solid electrolyte layer 25 and the cathode film 2 described later.
6 may be formed), thereby forming a dielectric film 24 such as tantalum pentoxide on the surface of the metal powder in each chip piece 22.

In forming the dielectric film 24 such as tantalum pentoxide on the surface of the metal powder in each chip piece 22, the following method may be employed. That is, among the anode rods 23 in each of the chip pieces 22, the chip pieces 2
When the synthetic resin 28 such as epoxy resin is applied to a portion between the one end face 22a of the lead 2 and the anode plate 27, as shown in FIG.
, The synthetic resin 28 is replaced with the synthetic resin 28
Is applied so as to adhere to the insulator sheet F, and in this state, the whole is immersed in a chemical conversion solution such as a phosphoric acid aqueous solution, and then subjected to anodic oxidation in which a direct current is applied to the chemical conversion solution. After that, the insulator sheet F is peeled off (this peeling operation may be performed after the solid electrolyte layer 25 and the cathode film 26 described later are formed), thereby obtaining FIG.
After forming a dielectric film 24 such as tantalum pentoxide on the surface of the metal powder in each chip piece 22, the insulating sheet F is separated from the lead frame E as shown in FIG. Thus, after the dielectric film 24 is formed by the anodic oxidation process, the dielectric film 24 on the surface side of each anode plate 27 is prevented from being separated and removed by polishing or the like as in the method described above. be able to.

After the dielectric film 24 is formed in this manner, each chip piece 22 is then replaced with the same as in the prior art.
By immersing in a manganese nitrate aqueous solution, withdrawing, drying and baking a plurality of times, a solid electrolyte made of a metal oxide such as manganese dioxide is formed on the surface of the dielectric film 24 as shown in FIG. The layer 25 is formed.

In this case, since the one end face 22a of the chip piece 22 and the anode rod 23 are covered with the synthetic resin 28, the chip piece 22 is placed in an aqueous manganese nitrate solution. Even if it is immersed beyond 22a, the formation of the solid electrolyte layer 5 on the one end surface 22a of the chip piece 22 and the anode rod 23 can be completely prevented by the synthetic resin 28.

When the dielectric film 24 and the solid electrolyte layer 25 are formed on each chip piece 22 in this manner, each chip piece 22 is immersed in a graphite aqueous solution on the surface of the solid electrolyte layer 25, pulled up, and dried. After forming a graphite layer by baking, a metal layer is formed by immersing in a plating solution and performing plating, thereby forming the cathode film 26 as shown in FIG.

In forming the graphite layer and the metal layer constituting the cathode film 26, the chip piece 22 may be immersed in an aqueous manganese nitrate solution and a plating solution beyond one end face 2a of the chip piece 22, The formation of the graphite layer and the metal layer on one end surface 22a of the piece 22 and the anode rod 23 can be completely prevented by the synthetic resin 21.

When the dielectric film 24, the solid electrolyte layer 25 and the cathode film 26 are formed on each chip piece 22 in this manner, the anode plate 27 to which the anode rod 23 protruding from the chip piece 22 is welded is formed. Is cut off from the lead frame A by punching to obtain a capacitor element 21 having a configuration as shown in FIG.

That is, the capacitor element 21 obtained here
Is a method of forming a dielectric film 24, a solid electrolyte layer 25, and a cathode film 26 on the tip piece 22 after welding an anode plate 27 to the tip of an anode rod 23 projecting from the tip piece 22. The anode rod 23
The thermal damage when welding the anode plate 27 to the dielectric film 24, the solid electrolyte layer 25 and the cathode film 26 in the chip piece 22 can be completely eliminated, so that the anode rod 23 One end face 22 of the chip piece 22
a from the anode plate 27 to the anode plate 27 can be greatly reduced,
As a result, the length of the capacitor element 21 can be greatly reduced.

Further, after the synthetic resin 28 is applied to a portion of the anode bar 23 of the capacitor element 21 between the one end face 22a of the chip piece 22 and the anode plate 27, a dielectric is applied to the chip piece 22. Since the body film 24, the solid electrolyte layer 25, and the cathode film 26 are formed, the solid electrolyte layer 25 and the cathode film 26 formed for the chip piece 22 are electrically connected to the metal powder on the anode rod 23 and the chip piece 22. Can be reliably prevented by the synthetic resin 28 applied to the anode bar 23,
When the solid electrolyte layer 25 and the cathode film 26 are formed by immersing the chip piece 22 in the processing liquid, the liquid level of the processing liquid is changed to one end face 22 of the chip piece 22 as in the related art.
It does not need to be strictly regulated to be located at a.

Further, the anode plate 27 is connected to the anode bar 23.
The anode plate 23 is welded to the flat plate at right angles to the axis of the capacitor plate 21 by welding the anode plate 23 to the length of the capacitor element 21 as in the prior art. Can be avoided, so that the length of the capacitor element can be further shortened. 10 to 13 show a solid electrolytic capacitor using the capacitor element 21 manufactured as described above.

That is, as shown in FIG. 10, the whole of the capacitor element 21 is
At 9, the outer surface of the anode plate 27 is
9 is sealed so that a part of the cathode film 26 of the chip piece 22 is exposed on the other end surface of the package 29, and the other end surface of the package 29 is
By forming 0 so as to be electrically connected to the cathode film 26, the surface mount type solid electrolytic capacitor 100 can be formed.

As shown in FIGS. 11 to 13, a box body 31 having an open upper surface is formed by an insulator such as a synthetic resin. And an anode terminal film 32 extending to the bottom surface via the inner surface and a cathode terminal film 33 also extending from the inner surface to the bottom surface via the outer surface, respectively, in the other end portion. The anode plate 27 is made of the conductive paste 3
4 is inserted into the anode terminal film 32 via the conductive paste 35 so that the cathode film 26 is electrically connected to the cathode terminal film 33 via the conductive paste 35. By fixing the cover plate 36 made of an insulator such as a resin and sealing the inside, a solid electrolytic capacitor 200 of a surface mount type can be formed.

In particular, according to the above-described embodiment, the capacitor element 21 can be manufactured by using the lead frame E and transferring the lead frame E in the longitudinal direction. A plurality is fixed to the metal bar by welding, and in this state, the dielectric film 24, the solid electrolyte layer 25, and the cathode film 26 are formed, and then, the production speed is significantly increased as compared with the conventional method of separating from the metal bar. There are advantages that can be up.

According to the above-described manufacturing method, in order to anodize each of the chip pieces 22 on which the valve action metal powder has been solidified, the entire lead frame E to which each of the chip pieces 22 is fixed by welding or the like is also used. When the metal powder of the piece 22 and the anode rod 23 are made of tantalum, they must be made of a valve metal having the same material as the metal powder of the chip piece 22 and the anode rod 23. Then, when the entire lead frame E to which the chip pieces 22 are fixed is anodized while being immersed in a chemical conversion solution,
Unless the entire lead frame E is made of an expensive valve action metal such as tantalum, the chip pieces 22 cannot be anodized, so that the manufacturing cost increases accordingly.

Therefore, according to the present invention, after the chip pieces 22 are fixed to the respective anode plates 27 of the lead frame E by welding, one end face of the chip pieces 22 of the anode rods 23 of the respective chip pieces 22 is formed. When a synthetic resin 28 such as an epoxy resin is applied to a portion between the anode frame 22a and the anode plate 27, before and after this, as shown in FIG. (The coating with the insulating film D 'may be performed simultaneously with the same synthetic resin when the synthetic resin 28 is applied. Alternatively, it may be performed by applying another synthetic resin.)

As described above, the entire lead frame E is covered with the insulating film D 'made of a synthetic resin or the like, so that the entire lead frame E to which the chip pieces 22 are fixed is anodized while being immersed in a chemical solution. At the time, lead frame E
Can be maintained in a state of being electrically insulated from the chemical conversion solution, so that each chip piece 22 can be anodized without using the lead frame E made of a valve metal such as tantalum.

Then, the insulating film D 'is removed after the anodic oxidation treatment or after the formation of the solid electrolyte layer 25 and the cathode film 26. This eliminates the need for the lead frame E, and thus the anode plate 27, to be made of a valve metal of the same material as the metal powder and the anode rod in the chip piece, and is made of copper or a copper alloy or carbon steel, or When the metal powder and the anode bar of the chip piece are made of tantalum, they can be made of less expensive metal such as aluminum, so that the manufacturing cost can be further reduced.

When the entire lead frame E is covered with the insulating film D 'made of a synthetic resin or the like, like the above-mentioned FIG.
The insulation sheet F may be bonded to the insulation sheet F and peeled off.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first step in an embodiment of the present invention.

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

FIG. 3 is a cross-sectional view showing a second step in the embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a third step in the embodiment of the present invention.

FIG. 5 is a sectional view showing a fourth step in the embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a step different from the second step.

FIG. 7 is a sectional view showing a step different from the fourth step.

FIG. 8 is a sectional view showing a fifth step in the embodiment of the present invention.

FIG. 9 is a vertical sectional front view of the capacitor element in the embodiment of the present invention.

FIG. 10 is a vertical sectional front view of a solid electrolytic capacitor using the capacitor element according to the present invention.

FIG. 11 is an exploded perspective view of another solid electrolytic capacitor using the capacitor element according to the present invention.

12 is a sectional view taken along the line XII-XII in FIG.

FIG. 13 is a vertical sectional front view of another solid electrolytic capacitor using the capacitor element according to the present invention.

FIG. 14 is a diagram showing another embodiment of the present invention.

FIG. 15 is a perspective view showing a capacitor element according to a conventional method.

FIG. 16 is a sectional view showing a first step according to a conventional method.

FIG. 17 is a sectional view showing a second step according to a conventional method.

FIG. 18 is a longitudinal sectional front view of a capacitor element according to a conventional method.

FIG. 19 is a vertical sectional front view of a solid electrolytic capacitor using a conventional capacitor element.

FIG. 20 is a vertical sectional front view of another solid electrolytic capacitor using a conventional capacitor element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Capacitor element 22 Chip piece 22a One end face of chip piece 23 Anode rod 24 Dielectric film 25 Solid electrolyte layer 26 Cathode film 27 Anode plate 28 Synthetic resin 29 Package body

Claims (3)

[Claims] At least a step of solidifying and molding a valve metal powder into a porous chip piece so that an anode rod protrudes from one end face of the chip piece, and welding an anode plate to a tip of the anode rod. And a method for manufacturing a capacitor element comprising a step of forming at least a dielectric film, a solid electrolyte layer and a cathode film on the chip piece, after the step of welding an anode plate to the tip of the anode rod, After adding a step of applying a synthetic resin to a portion of the anode bar between one end surface of the chip piece and the anode plate, a dielectric film, a solid electrolyte layer, and a cathode film are formed on the chip piece. A method for manufacturing a capacitor element in a solid electrolytic capacitor, characterized by shifting to a step of performing the following. 2. The solid according to claim 1, wherein the anode plate is a flat plate perpendicular to the axis of the anode bar, and the anode bar is welded to the anode plate by contacting the tip end surface thereof. A method for manufacturing a capacitor element in an electrolytic capacitor. 3. The anode plate according to claim 1, wherein an insulating coating is applied to the anode plate before and after the step of applying a synthetic resin to a portion of the anode bar between one end surface of the chip piece and the anode plate. Forming a dielectric film on at least the chip piece, and then adding a step of removing the insulating film on the anode body. .