JPH0722089B2 - Solid electrolytic capacitor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a solid electrolytic capacitor, and more particularly to improvement of 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 attaching a sealing body made of elastic rubber to the opening of a bottomed cylindrical outer case that houses the capacitor element.

When downsizing an electrolytic capacitor having such a sealed structure, it is necessary to downsize this sealed structure at the same time, but in order to maintain a sufficient degree of sealing, a certain space for mounting a sealing body and a sealed It is indispensable to provide a means, which makes it difficult to downsize the electrolytic capacitor. Therefore, although various proposals have been made for chip-type electrolytic capacitors, which are premised on downsizing of the electrolytic capacitor body, for example, the height from the printed circuit board is 10 mm.
However, it is 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, for example, manganese dioxide 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 the conventional solid electrolytic capacitor is limited to about 0.1 to 10 μF. Further, its impedance characteristic is superior to that of an electrolytic capacitor using an electrolytic solution, but 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, in recent years, there have been proposed those in which an organic conductive compound such as tetracyanoquinodimethane (TCNQ) or polypyrrole is applied to a solid electrolytic capacitor. For example, a solid electrolytic capacitor using polypyrrole is disclosed in JP-A-63-
158829, JP-A-63-173313, JP-A-1-228122,
JP-A-1-232712, JP-A-1-231605, JP-A-1-
No. 243510, JP-A 1-260809, and JP-A 1-268111 are mentioned.

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

However, the TCNQ complex tends to lack chemical stability and is particularly inferior 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, it may be transformed by the soldering temperature that normally rises around 260 ° C, which is not suitable for chip formation. Met.

A solid electrolytic capacitor using polypyrrole as an electrolyte has excellent heat resistance because the electrolyte is polymerized,
It is said to be optimal for chipping.

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 there is a case where the field is lost due to mechanical stress such as twisting of the anode body as the base body and external pressing.

In the case of surface-mounting a general chip-type electronic component on a printed circuit board, it is transferred from a supply source and mounted by a jig such as a suction nozzle. At this time, it is said that the component body is overloaded by about 1 kg due to the pressure of the suction nozzle. If it is a normal electronic component, it can withstand such an excessive load due to the exterior resin, etc., but when polypyrrole with poor mechanical strength is used as the electrolyte layer and it is made thin to achieve miniaturization, the polypyrrole layer is adsorbed. It may be damaged by the pressure of the nozzle.

Further, the properties of polypyrrole vary depending on the water content. Therefore, an exterior structure having improved moisture resistance is required.

Such a requirement can be satisfied by forming a polypyrrole layer on a solid block-shaped anode body and coating the exterior with a thick exterior resin, as in the conventional solid electrolytic capacitor. However, this would hinder the miniaturization of the entire component, and as described above, it was difficult to make the external dimensions of the same level as the ceramic capacitor.

An object of the present invention is to provide a highly reliable chip-type electronic component that has sufficient rigidity as a chip-type electronic component and will not be damaged even when mounted on a printed circuit board, even if the electrolyte layer has weak mechanical strength. It is to provide a solid electrolytic capacitor.

[Means for Solving the Problems]

The present invention provides a solid electrolytic capacitor in which an anode body having an oxide film layer, an electrolyte layer and a conductive layer formed on a surface in order is arranged on both sides of a strip-shaped cathode body so that the conductive layer of the anode body is in contact with the cathode body. It is characterized in that at least one of the plurality of anode bodies arranged on both surfaces is a frame body having continuous protrusions formed on the outer peripheral portion thereof.

Further, it is characterized in that the cathode body whose both surfaces are sandwiched by the anode body is led out to the outside from a notch provided in a part of the frame-shaped anode body.

[Work]

As shown in the drawings, in the present invention, a mechanically fragile electrolyte layer 3, for example, a polypyrrole layer is sandwiched by a strong anode body 1a having at least one formed in a frame shape, and the electrolyte layer 3 is mechanically separated. In addition to being able to protect against physical stress and moisture in the atmosphere, it becomes possible to form a thin outer resin layer on the outer surface thereof. Therefore, the size of the component is reduced while improving the mechanical strength of the component 2
It can meet one demand at the same time.

Further, as another means, since the notch 16 is provided in a part of the frame-shaped anode body 13, and the cathode body is led out from the notch 16,
The exposed portions of the conductive layer and the electrolyte layer can be minimized, and the exposed portions can be easily covered with the exterior resin.

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

FIG. 1 is a perspective view showing a solid electrolytic capacitor according to an embodiment of the present invention, and FIG. 2 is a sectional view thereof. FIG. 3 is a perspective view showing an anode body used in the examples, FIG. 4 is a conceptual diagram illustrating a production process of an electrolyte layer and the like, and FIG. 5 is an exploded perspective view of a solid electrolytic capacitor according to the examples. FIG. 6 is a perspective view showing an anode body used in the second embodiment of the present invention.

One of the anode bodies 1 (anode body 1a) is made of a frame-shaped aluminum or its alloy in which a continuous protrusion 2 is provided on the peripheral edge of a plate-shaped surface 8 as shown in FIG. Become.
The frame-shaped anode body 1a is formed by pressing the surface of an aluminum plate or performing a partial etching treatment at a selected position.

The surface 8 of the anode body 1a surrounded by the protrusions 2 is roughened, and a dielectric oxide film layer made of aluminum oxide is formed by electrolytic oxidation. Then, as shown in FIG. 4, this anode body 1a was immersed in a pyrrole solution containing an oxidant to form a pyrrole thin film by chemical polymerization, and then in an electrolytic solution for electrolytic polymerization in which pyrrole was dissolved. By immersing in and applying a voltage, an electrolyte layer 3 composed of a polypyrrole layer having a thickness of several μ to several tens of μ is selectively formed on the surface of the anode body 1a, particularly on the surface 8 surrounded by the protrusions 2. (Fig. 4 (b)).

Further, the conductive layer 4 is screen-printed on the surface of the electrolyte layer 3 (FIG. 4 (c)). The conductive layer 4 may have either a multi-layer structure composed of carbon paste and silver paste or a single-layer structure composed of a conductive adhesive containing metal powder having good conductivity.

Further, as shown in FIG. 5, the cathode body 5 is made of strip-shaped aluminum or its alloy. In this embodiment, the wide electrode portion 9 and the narrow terminal portion 10 provided at the end portion thereof are provided. Consists of.

The other anode body 1b is made of plate-shaped aluminum or an alloy thereof, and a resist layer 11 made of an insulating material is selectively formed on one surface thereof, and the non-selected surface of the resist layer 11 is, Similar to the frame-shaped anode body 1a, an oxide film layer, an electrolyte layer, and a conductive layer 12 are sequentially formed.

These frame-shaped anode body 1a, cathode body 5 and plate-shaped anode body
As shown in FIG. 5, the layers 1b are stacked on both surfaces of the cathode body 5 so that the conductive layers 4 and 12 of the anode bodies 1a and 1b are in contact with each other, as shown in FIG. A solid electrolytic capacitor is formed. In addition, the anode terminal 6 shown in FIG.
Are connected to one or both end faces of the anode body 1 by means of ultrasonic welding, laser welding or the like.

The terminal portion 10 of the cathode body 5 is, as shown in FIG.
Although protruding from the end surface of the anode body 1, the gap between the terminal portion 10 and the anode body 1 is sealed with a heat-resistant synthetic resin 7 or the like.

Although not shown, the surface of the anode body 1 is coated with a thermosetting heat-resistant resin, and the anode terminal 6 and the terminal portion 10 of the cathode body 5 connected to the anode body 1 are bent along the side surface of the anode body 1. Good.

In such a solid electrolytic capacitor, as shown in FIG. 2, since the cathode body 5 is sandwiched by a plurality of electrolyte layers via the conductive layer, the connection structure is simple and the cathode body 5 is When formed with a lead frame, mass productivity is improved. Further, as in the conventional case, the conductive layer and the cathode body 5
Since there is no need to coat the resin directly on the connection part with, other than resin sealing such as potting as in the past,
It becomes possible to coat the resin by methods such as molding and injection, which improves the dimensional accuracy of the appearance, makes it easy to display the polarity on the exterior, etc. and has high quality, and also simplifies the resin coating process itself. Become.

Further, since the electrolyte layer is sandwiched between at least the frame-shaped anode body 1a and the plate-shaped anode body 1b, it is not directly subjected to mechanical stress from the outside.

Further, regarding the sealing of the electrolyte layer itself, only the portion where at least one of the anode bodies 1a is sealed by the protrusion 2 formed on the peripheral end portion and further the terminal portion 10 of the cathode body 5 is projected is made of the synthetic resin 7 or the like. By sealing with, the outside air can be shielded.
Therefore, the overall external dimensions can be further reduced.

In the embodiment, the cathode body 5 is made of solderable metal such as copper, but a clad material of aluminum and solderable metal such as copper may be used.
In addition, one surface of the cathode body 5, particularly the surface facing the anode body 1, is subjected to an insulation treatment such as coating with a resin, and the cathode body 5 is bent.
Can also be brought into close contact with the anode body 1.

Next, a second embodiment of the present invention will be described.

In this embodiment, the anode body 13 arranged on both surfaces of the cathode body (not shown) has a continuous protrusion 14 formed at the peripheral end as shown in FIG. The one in which the part 16 is formed is used. An oxide film layer, an electrolyte layer and a conductive layer are formed on the surface 15 of the anode body 13 surrounded by the protrusions 14. The cathode body not shown is the first
Similar to the embodiment of the above, the notch portion 16 of the anode body 13 is sandwiched by the anode bodies 13 from both sides and the terminal portions are arranged on both sides.
Is derived from the outside. Further, the anode bodies 13 are welded to each other at the protruding portions 14 that are in contact with each other by using a means such as ultrasonic welding.

In this embodiment, the anode body 13 arranged on both sides of the cathode body
Both have a protrusion 14 formed at the peripheral end thereof and are welded by means such as ultrasonic welding, so that they are solid bodies having more excellent mechanical strength and sealing performance as compared with the first embodiment. An electrolytic capacitor can be obtained.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY As described above, the present invention provides a solid electrolytic capacitor in which an anode body having an oxide film layer, an electrolyte layer and a conductive layer sequentially formed on the surface is arranged so that the conductive layers of the anode body are in contact with both surfaces of a strip-shaped cathode body. In, at least one of the plurality of anode bodies arranged on both surfaces of the cathode body is characterized in that it is a frame body in which a continuous projection is formed on the outer peripheral portion, so that mechanical stress from the outside Are suppressed by the anode body. Therefore, for example, the electrolyte layer will not be damaged even by the pressing of the suction nozzle in the automatic mounting process, and a highly reliable solid electrolytic capacitor can be obtained, and the anode body having the electrolyte layer formed on both surfaces of the cathode property Will be arranged, and the capacity can be increased.

Further, since the frame-shaped anode body is disposed on at least one side of the exterior, the upper and lower surfaces and side surfaces thereof are surrounded by strong aluminum, and the accuracy of the external dimensions is improved. Therefore, the positioning process in the automatic mounting on the printed circuit board becomes accurate and simple, and the printing of the rating, the polarity display, etc. becomes easy.

Further, the cathode body is sandwiched via the electrolyte layer and the conductive layer formed on the anode body, and is drawn out to the outside as it is.
Therefore, the cathode body protruding to the outside is bent along the outer surface of the anode body without connecting to other terminals for external connection, etc., and a solid electrolytic capacitor compatible with surface mounting on a printed circuit board is manufactured. can do.

[Brief description of drawings]

FIG. 1 is a perspective view showing a solid electrolytic capacitor according to an embodiment of the present invention, and FIG. 2 is a sectional view thereof. FIG. 3 is a perspective view showing an anode body used in the examples, FIG. 4 is a conceptual diagram illustrating a production process of an electrolyte layer and the like, and FIG. 5 is an exploded perspective view of a solid electrolytic capacitor according to the examples. FIG. 6 is a perspective view showing an anode body used in the second embodiment of the present invention. 1,13 …… Anode body, 2,14 …… Projection part, 3 …… Electrolyte layer, 4,12 …… Conductive layer, 5 …… Cathode body, 6 …… Anode terminal, 7 …… Synthetic resin, 8, 15 …… Anode body surface, 9 …… Electrode section, 10 …… Terminal section, 11 …… Resist layer, 16 …… Notch section

Claims (2)

[Claims] 1. A solid electrolytic capacitor in which an anode body having an oxide film layer, a solid electrolyte layer and a conductive layer formed on the surface thereof in order is arranged so that the conductive layers of the anode body are in contact with both sides of a strip-shaped cathode body. A solid electrolytic capacitor, wherein at least one of a plurality of anode bodies arranged on both surfaces of a cathode body is a frame body having continuous projections formed on an outer peripheral portion thereof. 2. The solid electrolytic capacitor according to claim 1, wherein the cathode body having both surfaces sandwiched by the anode body is led out to the outside from a notch formed in a part of the frame-shaped anode body.