JPH0648671B2 - Method for manufacturing solid electrolytic capacitor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a solid electrolytic capacitor, and more particularly to a method for manufacturing a chip-type solid electrolytic capacitor using an organic conductive compound.

[Conventional technology]

In recent years, electronic components have been made into chips due to demands for miniaturization of electronic devices and efficient mounting on a printed circuit board.
Along with this, demands for making electrolytic capacitors into chips have increased, and various proposals have been made.

However, in the case of an electrolytic capacitor, particularly an electrolytic capacitor using an electrolytic solution as an electrolyte, it is necessary to seal the electrolytic solution in a fixed storage space. Generally, such sealing is performed by mounting a sealing body made of elastic rubber in an opening of a bottomed cylindrical outer case that houses a capacitor element.

Therefore, even if such an electrolytic capacitor is made into a chip, for example, the height dimension from the printed circuit board is 10 mm to 4 mm.
The limit is about mm, and it has been extremely difficult to realize a chip-type electrolytic capacitor of about 1 mm to 3 mm, which is equivalent to the external dimensions of a ceramic capacitor.

On the other hand, a solid electrolytic capacitor that does not use an electrolytic solution is generally formed by forming a solid electrolyte layer made of manganese dioxide or the like on an anode body made of tantalum or the like having an oxide film layer formed on the surface thereof, and further forming a carbon paste and It is configured by forming a conductive layer made of silver paste or the like.

Since such a solid electrolytic capacitor has a solid electrolyte, 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. Although its impedance characteristic is superior to that of an electrolytic capacitor using an electrolytic solution, it is still insufficient as compared with a ceramic capacitor or the like, and the cost increases when tantalum is used for the anode body.

[Problems to be Solved by the Invention]

By the way, recently, tetracyanoquinodimethane (TCN
Q), polypyrrole and other organic conductive compounds applied to solid electrolytic capacitors have been proposed.

Since these solid electrolytic capacitors have higher electric conductivity than solid electrolytes made of conventional metal oxide semiconductors, they have excellent high frequency impedance characteristics and do not require liquid to be sealed in the electrolytic capacitor body. Therefore, miniaturization is easy.

However, the TCNQ complex tends to lack chemical stability and is particularly poor in heat resistance. Therefore, it was not suitable for surface mounting on a printed circuit board.

Polypyrrole has high conductivity, and a solid electrolytic capacitor using this as an electrolyte is said to be suitable for chip formation because it has excellent heat resistance because the electrolyte is polymerized.

This polypyrrole is produced on the surface of the anode body by chemical polymerization, electrolytic polymerization, vapor phase polymerization or the like of pyrrole. However, the mechanical strength of this polypyrrole itself is weak, and the electrolyte layer may be damaged by the mechanical stress applied to the anode body during the manufacturing process. Therefore, precise processing accuracy is required in the manufacturing process, and the manufacturing is not easy.

An object of the present invention is to provide a highly reliable solid electrolytic capacitor which has sufficient rigidity as a chip type electronic component and is not damaged during the manufacturing process even if the electrolyte layer has weak mechanical strength. To do.

[Means for Solving the Problems]

According to the present invention, a plurality of anode bodies each having a concave portion in which an oxide film layer, an electrolyte layer and a conductive layer are sequentially formed are provided, and the conductive layers of the anode body are provided on both sides of a connection portion formed at regular intervals in a lead frame. It is characterized in that the lead frame is joined so as to face each other and the lead frame is cut at the connection portion.

[Action]

As shown in the drawings, in the present invention, a mechanically fragile electrolyte layer 3, for example, a polypyrrole layer is formed in a concave portion 6 formed in a part of the anode body 1 together with the conductive layer 4, and a relative convex portion 7 is formed. You will be surrounded. On the other hand, the lead frame 9
Is made of aluminum or the like, and is formed in a comb shape in which the connection portions 11 are projected on the strip-shaped base 10 at regular intervals. Then, a plurality of anode bodies 1 are placed on both surfaces of the connecting portion 11 of the lead frame 9 so that the conductive layers 4 thereof face each other, and the lead frame 9 is cut at the connecting portion 11 to form individual solid electrolytic cells. Get the capacitor.

Therefore, since the electrolyte layer 3 is shielded from the outside by the reinforced anode body 1, it is not necessary to seal the electrolyte layer 3 itself from the outside air. Further, by disposing the anode body 1 on both surfaces of the lead frame, the lead frame 9 serving as the cathode body 5 and the electrolyte layer 3 can be electrically connected, which simplifies the connection structure and leads the leads. After being separated from the frame 9, the contact portion 11 of the lead frame 9 serving as the cathode body 5 can be used as it is as a terminal for external connection.

〔Example〕

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

FIG. 1 is a partial cross-sectional perspective view illustrating a manufacturing process according to an embodiment of the present invention, FIG. 2 is a perspective view showing an anode body used in this embodiment, and FIG. 3 is formed according to an embodiment of the present invention. FIG. 4 is a partial cross-sectional view showing the conceptual structure of the solid electrolytic capacitor thus prepared, and FIG. 4 is a perspective view showing the solid electrolytic capacitor according to the embodiment.

The plate-shaped anode body 1 is made of a valve metal such as aluminum and has a depth of about 100 μm in a part thereof as shown in FIG.
The selective recess 6 is formed. The recess 6 may be formed by any means of mechanical processing such as press working and cutting, or chemical processing such as chemical etching. Then, in order to increase the surface area in the recess 6, an etching process, for example, an electrolytic etching process is performed to roughen the surface.

Next, the concave portion 6 of the anode body 1 is subjected to chemical conversion treatment 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 becomes a dielectric.

Further, the concave portion 6 of the anode body 1 is partially covered with a resin layer 8 by means of screen printing or the like, and the electrolyte layer 3 made of polypyrrole is formed on the non-coated surface of the resin layer 8. The electrolyte layer 3 is obtained by immersing the anode body 1 in a pyrrole solution containing an oxidant, forming a pyrrole thin film by chemical polymerization in the recess 6, and then immersing it in an electrolytic solution for electrolytic polymerization in which pyrrole is dissolved. It is generated by applying a voltage.

Next, the conductive layer 4 is screen-printed on the surface of the electrolyte layer 3. As a result, the electrolyte layer 3 and the conductive layer 4 are sequentially formed in the recess 6 of the anode body 1 as shown in FIG. The conductive layer 4 may have either a multi-layer structure made of carbon paste and silver paste or a single-layer structure made of a conductive adhesive containing metal powder having good conductivity.

The lead frame 9 is made of aluminum or its alloy, and as shown in FIG.
In addition, a plurality of connecting portions 11 are formed so as to project at regular intervals.

Then, as shown in FIG. 1 (b), the lead frame 9
The single anode body 1a is arranged at the connection portion 11 of the above. At this time,
The conductive layer 4 of the anode body 1a is brought into contact with the connecting portion 11. Furthermore,
Another anode body 1b is arranged on the opposite surface of the connection portion 11 so that the conductive layer 4 abuts on the connection portion 11 as in the case of the anode body 1a.
It is joined to the conductive layer 4 of the anode body 1 a via the connection portion 11.
Further, the anode body 1a and the anode body 1b are ultrasonically welded, if necessary.

Next, the anode terminal 2 for drawing out the anode is connected to the end surface of the lead frame 9 facing the end surface from which the connecting portion 11 is led out, by means of ultrasonic welding, laser welding, or the like.

Then, the lead frame 9 is cut at the connecting portion 11 to obtain a solid electrolytic capacitor as shown in FIG.
Since the connecting portion 11 of the lead frame 9 serves as the cathode body 5 of the solid electrolytic capacitor, the lead frame 9 is cut at a desired position according to the application. In this embodiment, although not shown, the anode body 5 was pushed and bent along the end face and the bottom face of the anode body 1, so that the lead frame 9 was cut at the base of the protruding portion.

In the solid electrolytic capacitor obtained as described above, as shown in FIG. 3, the electrolyte layer 3 is arranged on the connecting portion 11 of the lead frame 9, that is, on both surfaces of the cathode body 5, and the conductive layer 4 is interposed therebetween. Since they are connected to the cathode body 5 so as to be sandwiched, the electrical connection structure between the electrolyte layer 3 and the cathode body 5 is simplified.

In the manufacturing process, the anode bodies 1a and 1b are continuously arranged on the comb-shaped lead frame 9. Therefore, even fine solid electrolytic capacitors can be collectively transported, and the manufacturing process can be simplified.

In addition, in this embodiment, the lead frame 9 and the anode terminal 2 which become the cathode body 5 may use a clad material of aluminum and a solderable metal such as copper. In this case, solderable metal can be arranged on the surface of the printed circuit board facing the wiring pattern, and the surface mounting can be performed as it is.

〔The invention's effect〕

As described above, according to the present invention, in the method for manufacturing a solid electrolytic capacitor, a plurality of anode bodies having recesses in which an oxide film layer, an electrolyte layer and a conductive layer are sequentially formed are connected to a lead frame at regular intervals. Since the conductive layers of the anode body are joined to face each other on both sides of the part, and the lead frame is cut at the connecting portion, the cathode body and the electrolyte layer are electrically connected via the conductive layer. However, by arranging 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 for a long period of time.

Further, the electrolyte layer is protected from external mechanical stress by the anode bodies arranged on both sides of the cathode body, and is also shielded from the outside air by the resin layer covering a part of the recess of the anode pair. Therefore, the sealing accuracy inside the solid electrolytic capacitor is improved, and the electrical characteristics of the electrolyte layer, which is easily transformed with respect to moisture, can be maintained for a long period of time, and the life characteristics can be improved.

Further, since the anode body is continuously arranged on the comb-shaped lead frame in which the connection portions are formed on the base body at regular intervals, and the lead frame is cut at the connection portion, even a fine solid electrolytic capacitor can be obtained. In addition, the manufacturing process can be simplified by batch manufacturing and transporting.

[Brief description of drawings]

FIG. 1 is a partial sectional perspective view illustrating a manufacturing process according to an embodiment of the present invention, FIG. 2 is a perspective view showing an anode body used in this embodiment, and FIG. 3 is a view showing an embodiment of the present invention. FIG. 4 is a partial sectional view showing a conceptual structure of the formed solid electrolytic capacitor, and FIG. 4 is a perspective view showing a solid electrolytic capacitor according to an embodiment. 1 ... Anode body, 2 ... Anode terminal, 3 ... Electrolyte layer, 4 ... Conductive layer, 5 ... Cathode body, 6 ... Recessed portion, 7 ... Convex portion, 8 ... Resin layer, 9 ... Lead frame, 10 ... Base, 11 ... Connection part.

Claims (1)

[Claims] 1. A plurality of anode bodies each having a concave portion in which an oxide film layer, an electrolyte layer and a conductive layer are sequentially formed, and a conductive layer of the anode body is provided on both surfaces of a connecting portion formed at regular intervals on a lead frame. A method for manufacturing a solid electrolytic capacitor, characterized in that the lead frames are bonded so as to face each other and the lead frame is cut at a connecting portion.