JPH03284819A - Manufacture of solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To prevent the formation of an electrolytic layer from forming in the cutting surface of an anode body, to obviate the short circuit of the burr of the electrolytic layer or the anode body, to eliminate the need for a process, in which the burr, etc., are removed, and to interrupt the electrolytic layer from the outside air by the resin layer of the anode body by forming the resin layer covering one part of a recessed section and shaping the electrolytic layer while cutting the anode body in the resin layer. CONSTITUTION:When an electrolytic layer 3 is formed into the recessed section 6 of an anode body 1, a resin layer 8 composed of a synthetic resin is formed to one part of the recessed section 6 and the electrolytic layer 3 is formed. The anode body 1 is cut in the resin layer 8, and changed into a single anode body 1a. The anode body 1 is cut in the resin layer 8, to which the electrolytic layer 3 is not shaped, thus preventing the accident of a short circuit due to the burr of the anode body 1 or the electrolytic layer 3. The resin layer 8 faces to the cutting surface of the anode body 1a cut, thus shielding the electrolytic layer 3 from the outside air by the resin layer 8 together with a plurality of anode bodies 1a, 1b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to solid electrolytic capacitors, and particularly to improvements in chip-type solid electrolytic capacitors using organic conductive compounds.

[Conventional technology]

2. Description of the Related Art In recent years, electronic components have been made into chips due to demands for smaller electronic devices and more efficient mounting on printed circuit boards.

Along with this, the demand for Chi-nobu electrolytic capacitors has increased, and various proposals have been made.

However, in the case of an electrolytic capacitor, particularly an electrolytic capacitor that uses an electrolytic solution as an electrolyte, it is necessary to seal the electrolytic solution in a certain storage space. - In boat fishing, such sealing is performed by attaching a sealing body made of elastic rubber to the opening of a bottomed cylindrical exterior case that houses a capacitor element.

When miniaturizing an electrolytic capacitor with such a sealed structure, it is necessary to simultaneously downsize this sealed structure, but in order to maintain a sufficient degree of sealing, it is necessary to have a certain space for installing the sealing body, and to It is essential to provide a means, which makes it difficult to miniaturize electrolytic capacitors. For this reason, various proposals have been made regarding chip-type electrolytic capacitors that are based on the premise of downsizing the electrolytic capacitor body, but for example, the height dimension from the printed circuit board is 10 m.
The limit is about 4mm to 1m, which is equivalent to the external dimensions of a ceramic capacitor, from 1m to 3III
It was extremely difficult to realize a chip-type electrolytic capacitor of about I11.

On the other hand, solid electrolytic capacitors that do not use electrolyte are made by forming a solid electrolyte layer made of manganese dioxide, etc. on an anode body made of tantalum or the like with an oxide film layer formed on the surface, and then carbon paste. and a conductive layer made of silver paste or the like.

Since the electrolyte of such a solid electrolytic capacitor is solid, it is relatively easy to downsize and can be made into a chip.

However, the capacitance range of conventional solid electrolytic capacitors is limited to about 0.1 to 10 μF. In addition, although its impedance characteristics are superior to electrolytic capacitors using electrolyte, they are still insufficient compared to ceramic capacitors and the like, and if tantalum is used for the anode body, the cost will be high.

[Problem to be solved by the invention] In recent years, tetracyanoquinodimethane (TCNQ)
, solid electrolytic capacitors using organic conductive compounds such as polypyrrole have been proposed. For example, solid electrolytic capacitors using polypyrrole are disclosed in Japanese Patent Application Laid-open Nos. 158829-1982, 173313-1980,
JP-A-1-228122, JP-A-1-232712, JP-A-1-231605, JP-A-1-243510
No., JP-A No. 1-260809, JP-A No. 1-26811
Examples include No. 1.

These solid electrolytic capacitors have higher conductivity than conventional solid electrolytes made of metal oxide semiconductors, so they have particularly excellent impedance characteristics at high frequencies, and there is no need to seal liquid inside the electrolytic capacitor body. Therefore, miniaturization is easy.

However, TCNQ complexes tend to lack chemical stability, and are particularly poor in heat resistance. Therefore, in the case of a solid electrolytic capacitor in which an electrolyte layer made of a TCNQ complex is formed on the surface of an anode body made of aluminum, the electrolyte layer may be denatured due to the temperature during soldering, which is normally heated to around 260°C. It was unsuitable for chipping.

Polypyrrole has high conductivity, and solid electrolytic capacitors using polypyrrole as the electrolyte are said to be ideal for chipping because the electrolyte is polymerized and has excellent heat resistance.

This polypyrrole is produced on the surface of the anode body by chemical polymerization, electrolytic polymerization, gas phase polymerization, etc. of pyrrole. However, the mechanical strength of this polypyrrole itself is weak, and the electrolyte layer may be damaged due to mechanical stress applied to the anode body during the manufacturing process.

Furthermore, the properties of polypyrrole vary depending on moisture. Therefore, an exterior structure with moisture resistance is required.

Such a requirement can be met by forming a polypyrrole layer on a strong block-shaped anode body and covering the exterior with a thick exterior resin, as in conventional solid electrolytic capacitors.

However, this hinders miniaturization of the entire component, and as mentioned above, it has been difficult to make the external dimensions comparable to those of the ceramic capacitor.

The purpose of this invention is to provide a highly reliable solid electrolytic capacitor that has sufficient rigidity as a chip-shaped electronic component and will not be damaged during the manufacturing process even if the electrolyte layer has weak mechanical strength. It is about providing.

[Means to solve the problem]

This invention relates to a solid electrolytic capacitor in which an anode body having a concave portion in which an oxide film layer, an electrolyte layer, and a conductive layer are sequentially formed is disposed on both sides of a cathode body, in which a resin layer is formed to partially cover the concave portion. The method is characterized in that an electrolyte layer is formed later, and the anode body is cut in this resin layer.

[For production]

As shown in the drawings, in the present invention, a mechanically fragile electrolyte layer 3, such as a polypyrrole layer, is formed together with a conductive layer 4 in a recess 6 formed in a part of an anode body 1, and is formed in a relative protrusion 7. It will be surrounded. This anode body 1 is arranged on both sides of a strip-shaped cathode body 5. Therefore, the electrolyte layer 3 is shielded from the outside by the strong anode body l, and there is no need to seal the electrolyte layer 3 itself from the outside air. In addition, by arranging the anode body 1 on both sides of the cathode body 5, it is possible to electrically connect the electrolyte layer 3 and the cathode body 5, which simplifies the connection structure and allows the cathode body 5 to be left as it is. It can be used as a terminal for external connection.

Further, when forming the electrolyte layer 3 in the recess 6 of the anode body 1, the resin layer 8 made of synthetic resin is formed in a part of the recess 6, and then the electrolyte layer 3 is formed. Therefore, in the recess 6 of the anode body 1, a portion remains where the electrolyte layer 3 is not formed. Then, the anode body 1 is cut at this resin layer 8 to become a single anode body 1a. Normally, when the surface of an organic conductive compound such as polypyrrole that becomes the electrolyte layer 3 is cut, the electrolyte layer 3 will have cracks on the cut surface. Also, when cutting the anode body 1 from the main body side, the anode body 1
There is a problem in that the electrodes are short-circuited with the anode body 1 and cannot function as a capacitor.

However, in this invention, since the anode body 1 is cut at the resin layer 8 where the electrolyte layer 3 is not formed, it is possible to prevent a short circuit accident due to paris in the anode body 1 or the electrolyte layer 3. .

Further, the resin layer 8 faces the cut surface of the cut anode body 1a, and the electrolyte N3 is applied to the plurality of anode bodies 1a, 1b.
At the same time, this resin layer 8 shields it from the outside air.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a partial cross-sectional perspective view illustrating the manufacturing process according to an embodiment of the present invention, FIG. 2 is a partial cross-sectional view showing the conceptual structure of a solid electrolytic capacitor formed according to an embodiment of the present invention, and FIG. 1 is a perspective view showing a solid electrolytic capacitor according to an example.

The plate-shaped anode body 1 is made of a valve metal such as aluminum, and as shown in FIG.
A selective recess 6 of 00 μm is formed. The recess 6 may be formed by mechanical processing such as pressing or cutting, or chemical processing such as chemical etching. In order to enlarge the surface area within this recess 6, etching treatment, for example electrolytic etching treatment, is performed to roughen the surface.

Next, a chemical conversion treatment is applied to the recesses 6 of the anode body 1 to form an oxide film layer on the surface. This oxide film layer is made of aluminum oxide obtained by oxidizing the surface layer of the anode body 1 made of aluminum, and serves as a dielectric.

Furthermore, as shown in FIG. 1(b), a part of the recess 6 of the anode body 1 is coated with a resin layer 8 by means such as screen printing. This resin layer 8 is made of a heat-resistant synthetic resin, such as a phenol resin, and its installation location is at the anode body 1.
Set according to the cutting position.

Next, the anode body 1 is immersed in a virol solution containing an oxidizing agent to form a virol thin film in the recess 6 by chemical polymerization, and then immersed in an electrolytic solution for electrolytic polymerization in which virol is dissolved, and a voltage is applied. As a result, an electrolyte layer 3 made of a polypyrrole layer having a thickness of several μm to several tens of μm as shown in FIG. 2 is produced. The electrolyte layer 3 made of this polypyrrole layer is temporarily generated only in the area where voltage is applied.

Therefore, a polypyrrole layer is not generated in the portion of the recess 6 of the anode body 1 covered with the resin layer 8, and the resin layer 8 is exposed on the surface.

Next, a conductive layer 4 is screen printed on the surface of the electrolyte layer 3 (FIG. 1(C)). As a result, as shown in FIG. 2, the electrolyte layer 3 and the conductive layer 4
will be generated sequentially.

This conductive layer 4 may have either a multilayer structure made of carbon paste and silver paste, or a single layer structure made of a conductive adhesive containing metal powder with good conductivity.

Then, as shown in FIG. 1(C), this anode body 1 was cut at the resin layer 8, that is, at the cutting line χ where the electrolyte layer 3 was not formed, and the anode body 1 was cut as shown in FIG. A single anode body 1a is obtained. In addition, if necessary,
For example, a smaller solid electrolytic capacitor can be obtained by providing a resin layer 8 near the center of the anode body 1 and cutting the anode body 1.

As shown in FIG. 3, the cathode body 5 is made of a strip-shaped aluminum or an alloy thereof. A plurality of anode bodies 1a and 1b are arranged and bonded to both sides of this cathode body 5 so that their conductive layers 4 face each other, and ultrasonic welding is performed as necessary. Further, an anode terminal 2 for drawing out the anode is connected to the end face opposite to the end face from which the cathode body 5 is led out by ultrasonic welding, laser welding, or the like.

Although not shown, the anode terminals 2 are connected to the anode bodies 1a and 1b by insulating the outer surfaces of the anode bodies 1a and 1b.
Alternatively, the tip of the cathode body 5 may be bent along the side surfaces of the anode bodies 1a, 1b to bring them into close contact.

In the solid electrolytic capacitor obtained as described above, as shown in FIG. Therefore, the electrical connection structure between the electrolyte layer 3 and the cathode body 5 is simplified.

Further, on the cut surfaces of the anode bodies 1a and 1b, the resin layer 8
are arranged, and the electrolyte layer 3 is arranged between the anode bodies 1a and 1
In addition to b, this resin layer 8 isolates it from the outside air and improves moisture resistance.

In addition, in this embodiment, the cathode body 5 and the anode terminal 2
Although a material made of a metal such as copper that can be soldered is used in the above, a crand material made of aluminum and a metal that can be soldered such as copper may also be used.

Further, the resin layer 8 covering a part of the recess 6 of the anode body 1 is
In this embodiment, the anode body 1 was provided by screen printing after being subjected to a chemical conversion treatment, but the anode body 1 may be coated with a synthetic resin having high chemical resistance as a step before the chemical conversion treatment. In this case, the resin layer 8 is coated on the recess 6 on the surface of which no oxide film layer is formed, and the adhesion of the resin layer 8 becomes stronger.

〔Effect of the invention〕

As described above, the present invention provides a solid electrolytic capacitor in which an anode body having a concave portion in which an oxide film layer, an electrolyte layer, and a conductive layer are sequentially formed is disposed on both sides of a cathode body, in which a resin layer partially covers the concave portion. After forming an electrolyte layer, the anode body is cut at this resin layer. Therefore, an electrolyte layer is not formed on the cut surface of the anode body, and therefore the electrolyte layer or the anode body is cut. Paris will no longer be short-circuited. Therefore, the process of removing bulges and the like becomes unnecessary, the manufacturing process can be simplified, and a highly reliable solid electrolytic capacitor can be obtained.

In addition, the cathode body and the electrolyte layer are electrically connected via a conductive layer, but by simply placing the anode body on both sides of the cathode body,
This electrical connection is maintained. Therefore, the connection structure is simple, the manufacturing process is easy, and a stable connection state can be maintained over a long period of time.

Further, the electrolyte layer is protected from external mechanical stress by the anode body disposed on both sides of the cathode body, and is also shielded from the outside air by a resin layer covering a portion of the recessed portion of the anode body. Therefore, the sealing accuracy inside the solid electrolytic capacitor is improved, the electrical characteristics of the electrolyte layer that is easily denatured by moisture can be maintained for a long period of time, and the life characteristics can be improved.

Furthermore, on the cut surface of the anode body, it is necessary to electrically insulate the anode body and the cathode body, but this is not necessary because the resin layer formed in the recessed part of the anode body faces the cut surface of the anode body. It also disappears.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional perspective view illustrating the manufacturing process according to an embodiment of the present invention, and FIG. 2 is a partial cross-sectional view showing the conceptual structure of a solid electrolytic capacitor formed according to an embodiment of the present invention. FIG. 3 is a perspective view showing a solid electrolytic capacitor according to an embodiment. DESCRIPTION OF SYMBOLS 1... Anode body 1.2... Anode terminal, 3... Electrolyte layer, 4... Conductive layer, 5... Cathode body, 6... Concave part, 7... Convex part, 8 ...resin layer.

Claims (1)

[Claims] (1) In a solid electrolytic capacitor in which an anode body with a recess in which an oxide film layer, an electrolyte layer, and a conductive layer are sequentially formed is placed on both sides of a cathode body, a resin layer is formed to cover a part of the recess. A method for manufacturing a solid electrolytic capacitor, which comprises generating an electrolyte layer and cutting an anode body in this resin layer.