JPH0766079A - Manufacture of capacitor element in solid electronic capacitor - Google Patents

Abstract

PURPOSE:To manufacture a capacitor element in a solid electronic capacitor in a state of an enlarged volume of a chip piece in the capacitor element. CONSTITUTION:Aforesaid capacitor element 1 is dipped into a formation liquid such as a phosphoric acid water solution for performing anode oxidation so as to form a dielectric film, next, a tape 11 made of water-repellent synthetic resin is wound about the root part of an anode rod in the capacitor element in order to form a cathode side electrode film consisting of such as a metal film having a solid electrolytic layer and a graphite layer as a foundation on a chip piece 2 in a capacitor element.

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 of a solid electrolytic capacitor such as a tantalum solid electrolytic capacitor or an aluminum solid electrolytic capacitor.

[0002]

2. Description of the Related Art Generally, when manufacturing a capacitor element 1 used for a solid electrolytic capacitor of this type, first, a metal powder such as tantalum, as shown in FIG. Porous chip piece 2 such as oval shape
In the chip piece 2, the anode rod 3 made of metal such as tantalum.
The part is buried and molded, then sintered and
As shown in FIG. 8, the capacitor element 1 is immersed in a chemical conversion solution such as phosphoric acid aqueous solution A, so that the chemical conversion solution such as phosphoric acid aqueous solution A penetrates into the inside of the porous chip piece 2 to form a direct current. By applying an electric current and performing anodization,
A dielectric film 4 of tantalum pentoxide or the like is formed on the surface of each metal powder in the chip piece 2 and a part of the surface of the anode rod 3.

Next, the capacitor element 1 which has completed the step of forming the dielectric film 4 such as tantalum pentoxide is
As shown in FIG. 9, the manganese nitrate aqueous solution B is soaked until the upper surface of the chip piece 2 in the capacitor element 1 does not become lower than the liquid surface of the manganese nitrate aqueous solution, and the manganese nitrate aqueous solution B is added to the chip piece 2. The dielectric film 4 made of tantalum pentoxide or the like is obtained by repeating the process of penetrating into the inside of the substrate and then lifting and firing it a plurality of times.
A solid electrolyte layer 5 made of a metal oxide such as manganese dioxide is formed on the surface of.

Then, a method of forming an electrode film on the cathode side by forming a metal film such as silver or nickel on the surface of the solid electrolyte layer 5 of the chip piece 2 in the capacitor element 1 using a graphite film as a base Has been adopted. By the way, in the manufacturing process of the capacitor element 1, after the dielectric film 4 made of tantalum pentoxide or the like is formed, the solid electrolyte layer 5 made of a metal oxide and the graphite film are used as a base and made of a metal film made of silver or nickel. When the cathode-side electrode film is formed, the manganese nitrate aqueous solution B or the like is soaked up to the portion of the anode rod 3, and the electrical insulation of the cathode-side electrode film from the anode rod 3 is impaired. Get higher

Therefore, conventionally, when the solid electrolyte layer 5 made of a metal oxide is formed after the dielectric film 4 made of tantalum pentoxide or the like is formed on the capacitor element 1, the solid electrolyte layer made of this metal oxide is used. Prior to formation of 5,
As shown in FIG. 10, a ring body C made of a water-repellent synthetic resin is fitted to the anode rod 3 after the dielectric film 4 such as tantalum pentoxide is formed, or the base portion of the anode rod 3 is Figure 11
As shown in FIG. 3, by coating the water-repellent synthetic resin D in a liquid state, it is possible to prevent the manganese nitrate aqueous solution B and the like from seeping up to the anode rod 3 when forming the cathode side electrode film. ing.

[0006]

However, as in the former method, the ring rod C made of water repellent synthetic resin is fitted on the anode rod 3 of the capacitor element 1 by the ring rod C.
In addition to the fact that the mounting position for the anode rod 3 is not determined, the ring body C is inclined with respect to the anode rod 3 as shown by the chain double-dashed line in FIG. There is a large variation in the so-called neck size S from the above to the upper surface of the ring body C.

As in the latter method, the water-repellent synthetic resin D is applied to the base of the anode rod 3 in the capacitor element 1 in a liquid state. The water-repellent synthetic resin is applied from the upper end surface 2a of the chip piece 2. So-called neck dimension S up to the upper surface of resin D
However, since the amount of the water-repellent synthetic resin D varies greatly, the variation in the neck dimension S is also large.

Therefore, by using the capacitor element 1 manufactured by these conventional methods, a solid electrolytic capacitor 10 as shown in FIG. 12 (the capacitor element 1 is provided between a pair of left and right lead terminals 6, 7). Capacitor element 1
After fixing the anode rod 3 in 1 to one lead terminal 6 and connecting the chip piece 2 to the other lead terminal 7 directly or via a safety fuse,
In assembling a synthetic resin molded part 8), the gap dimension T between the upper end surface 2a of the chip piece 2 in the capacitor element 1 and one lead terminal 6 is set to the neck of the capacitor element 1. The size must be increased according to the large variation of the dimension S.

On the other hand, since the solid electrolytic capacitor 10 has a fixed total length L, under these conditions, the upper end surface 2 of the chip piece 2 in the capacitor element 1 will be described.
In order to increase the gap size T between a and one of the lead terminals 6 according to the large variation in the neck size S, the length W of the chip piece 2 in the capacitor element 1 is reduced by that amount. Since it is necessary to reduce the volume of the chip piece 2 and thus the capacitance of the solid electrolytic capacitor, the large variation in the neck size S of the capacitor element 1 prevents the solid electrolytic capacitor from having a large capacitance. It was.

It is a technical object of the present invention to provide a method for manufacturing the above-mentioned capacitor element in a state where variations in neck size of the solid electrolytic capacitor are reduced.

[0011]

In order to achieve this technical object, the present invention provides a "capacitor element comprising a chip piece obtained by sintering metal powder and an anode rod protruding from the chip piece, a phosphoric acid aqueous solution. To form a dielectric film such as tantalum pentoxide by immersing it in a chemical solution such as tantalum pentoxide, and then wrapping a tape made of a water-repellent synthetic resin around the base of the anode rod. The solid electrolyte layer made of a metal oxide such as manganese dioxide and the graphite film are used as bases to form the cathode side electrode film made of a metal film such as silver or nickel. "

[0012]

[Operation] By wrapping the synthetic resin tape made of water-repellent material around the root of the anode rod in the capacitor element, the chip piece is made of solid metal oxide such as manganese dioxide. When forming the cathode side electrode film made of a metal film such as silver or nickel on the basis of the electrolyte layer and the graphite film as a base, surely prevent the manganese nitrate aqueous solution from seeping up to the part of the anode rod with the tape. You can

In this case, the tape has a certain width, and by winding the tape around the root of the anode rod, the tape is displaced relative to the anode rod in the axial direction of the anode rod. Since it can be securely fixed in place without doing so, the so-called under-neck dimension from the upper end surface of the chip piece to the upper surface of the tape can be made almost the same for many capacitor elements, and the variation in the under-neck dimension can be made. Can be made much smaller than when the ring body is fitted onto the anode rod or the synthetic resin liquid is applied as in the conventional case.

[0014]

As described above, according to the present invention, it is possible to significantly reduce the variation in the under-neck size required when forming the anode-side electrode film in the production of the capacitor element. When assembling a solid electrolytic capacitor, make the gap between the upper end surface of the chip piece and one of the lead terminals in the capacitor element smaller than the conventional case because of the small variation in the under-neck dimension. Can be done.

As a result, the length of the chip piece in the capacitor element can be increased as much as the gap size can be reduced without increasing the total length of the solid electrolytic capacitor, and the volume of the chip piece is increased. Therefore, it is possible to increase the capacity of the solid electrolytic capacitor.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. First, as shown in FIG. 8, the capacitor element 1 as shown in FIG. 7 is immersed in a chemical conversion solution such as phosphoric acid aqueous solution A, so that the phosphoric acid aqueous solution A is put inside the porous chip piece 2. A DC current is applied to the surface of each metal powder in the chip piece 2 and a part of the surface of the anode rod 3 by applying a direct current in a state of permeating a chemical solution such as tantalum pentoxide. The body film 4 is formed (up to this point, it is the same as the conventional one).

After forming the dielectric film 4 of tantalum pentoxide or the like, as shown in FIG. 1, silicon, tetralafluoroethylene, polyimide or the like is formed at the base of the anode rod 3 in the capacitor element 1. A water-repellent synthetic resin tape 11 is wrapped around. Then, as in the conventional case, as shown in FIG. 9, the capacitor element 1 is adjusted so that the upper surface of the chip piece 2 in the capacitor element 1 does not become lower than the liquid surface of the manganese nitrate aqueous solution with respect to the manganese nitrate aqueous solution B. By dipping, and permeating the manganese nitrate aqueous solution B into the inside of the chip piece 2 and then withdrawing and firing it several times, a metal such as manganese dioxide or the like is formed on the surface of the dielectric film 4 such as tantalum pentoxide. After the solid electrolyte layer 5 made of an oxide is formed, a metal film such as silver or nickel is formed on the surface of the solid electrolyte layer 5 by using a graphite film as a base to form an electrode film on the cathode side.

When forming the cathode-side electrode film composed of the solid electrolyte layer 5, the graphite film and the metal film, a tape 11 made of a water-repellent synthetic resin is wound around the root of the anode rod 3 in the capacitor element 1. As a result, the manganese nitrate aqueous solution B can be reliably prevented from bleeding onto the anode rod 3 by the tape 11.

When the tape 11 is wound around the root of the anode rod 3, as shown in FIGS. 2 and 3, the tip of the tape 11 whose back surface is coated with a pressure sensitive adhesive is attached to the anode rod 3. After sticking to, capacitor element 1
The tape 11 may be wound around by rotating, or as shown in FIGS. 4 and 5, the tape 11 having a pressure-sensitive adhesive applied on the back surface may be attached to the anode rod 3 at both ends thereof. The tape 11 may be wound by sticking it together, and the tape 11 made of a heat-shrinkable synthetic resin can be tightly wound around the anode rod 3.

The tape 11 has a certain width, and this tape 11 is used as the anode rod 3
By wrapping around the root portion of the anode rod 3, it is possible to securely fix the anode rod 3 at a predetermined position without shifting in the axial direction of the anode rod 3, so that from the upper end surface 2a of the tip piece 2 The so-called under-neck dimension S up to the upper surface of the tape 11 can be made substantially the same for a large number of capacitor elements, and the variation in the under-neck dimension S can be caused by fitting the ring body to the anode rod as in the conventional case. ,
Alternatively, it can be made much smaller than when a synthetic resin liquid is applied.

Therefore, using this capacitor element 1, a solid electrolytic capacitor 10 as shown in FIG. 6 (similar to the conventional case, the capacitor element 1 is provided with a pair of left and right lead terminals 6, 7).
After that, the anode rod 3 of the capacitor element 1 is fixed to one lead terminal 6 and the chip piece 2 is connected to the other lead terminal 7 either directly or through a safety fuse. When the whole is packaged in a mold part 8 made of synthetic resin), the gap size T between the upper end surface 2a of the chip piece 2 and one lead terminal 6 in the capacitor element 1 is Under neck size S
By reducing the variation of the above, it is possible to make it smaller than in the conventional case, so that the length dimension of the chip piece in the capacitor element can be increased without increasing the total length dimension L in the solid electrolytic capacitor 10. Since the volume of the chip piece 2 can be increased, it is possible to increase the capacity of the solid electrolytic capacitor 10.

[Brief description of drawings]

FIG. 1 is a front view of a state where a tape is wound around an anode rod in a capacitor element in an example of the present invention.

FIG. 2 is a perspective view showing an example of a method of winding a tape around an anode rod.

FIG. 3 is a perspective view showing a state where the tape is wound by the winding method shown in FIG.

FIG. 4 is a perspective view showing another example of a method of winding a tape around an anode rod.

5 is a perspective view showing a state where the tape is wound by the winding method shown in FIG.

FIG. 6 is a vertical sectional front view of a solid electrolytic capacitor using a capacitor element manufactured by the method of the present invention.

FIG. 7 is a perspective view of a capacitor element.

8 is a diagram showing a state in which a process of forming a dielectric film of tantalum pentoxide or the like is performed on the capacitor element of FIG.

9 is a diagram showing a state in which a process for forming a solid electrolyte layer of a metal oxide such as manganese dioxide is being performed on the capacitor element of FIG.

FIG. 10 is a front view showing a conventional capacitor element.

FIG. 11 is a front view showing another conventional capacitor element.

FIG. 12 is a vertical cross-sectional front view of a solid electrolytic capacitor using a conventional capacitor element.

[Explanation of symbols]

 1 Capacitor Element 2 Chip Piece 3 Anode Rod 10 Solid Electrolytic Capacitor 6, 7 Lead Terminal 8 Mold Part 11 Tape

Claims (1)

[Claims] 1. A capacitor element comprising a chip piece obtained by sintering metal powder and an anode rod protruding from the chip piece,
A dielectric film such as tantalum pentoxide is formed by immersing it in a chemical conversion solution such as phosphoric acid aqueous solution and performing anodic oxidation.
After winding a water-repellent synthetic resin tape around the base of the anode rod, the chip piece is covered with a solid electrolyte layer made of a metal oxide such as manganese dioxide and a graphite film as an underlayer, and formed of silver or nickel. A method for manufacturing a capacitor element in a solid electrolytic capacitor, which comprises forming a cathode-side electrode film made of a metal film or the like.