JPH03200312A - Solid electrolytic capacitor - Google Patents

Abstract

PURPOSE:To contrive to miniaturize the whole parts by forming at least one of plural anode bodies to be arranged on both faces of a cathode body into a frame body with a continuous protrusion formed on the outer periphery. CONSTITUTION:Anode bodies 1a, 1b each with oxide film layer, electrolyte layer 3 and conductive layer successively formed on the surface are arranged on both faces of a beltlike cathode body 5 so that the conductive layers 4 of the anode bodies 1a, 1b come in contact with each other. Then, at least one of the plural anode bodies 1a, 1b to be arranged on both faces of the cathode body 5 is a frame body with a continuous protrusion 2 formed in the outer periphery. That is, at least one of the mechanically fragile electrolyte layers 3 is held by the film anode body 1a formed as a frame body so that the electrolyte layer 3 can be protected from mechanical stress, moisture in the air, etc., and a sheathing resin layer can be formed thinly on the external surface. Thus, parts can be miniaturized in shape while the mechanical strength of the parts themselves is improved.

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 chip-based 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 outer 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. Therefore, although various proposals have been made for chip-type electrolytic capacitors that are based on the premise of reducing the size of the electrolytic capacitor body, the limit is, for example, that the height from the printed circuit board is about 10 mm or 4 mm. It has been extremely difficult to realize a chip-type electrolytic capacitor with an external dimension of about 1 to 3 rm, which is equivalent to the external dimensions of a ceramic capacitor.

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, etc. (Also, 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, 173313-1983, 228122-1992, and 232712-1999.
No., JP-A No. 1-231605, JP-A No. 1-24351
No. 0, JP-A No. 1-260809, JP-A No. 1-2681
No. 11 etc. are mentioned.

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 solid electrolytic capacitors in which an electrolyte layer made of a TCNQ complex is formed on the surface of an anode body made of aluminum, the soldering, which normally rises to around 260°C, may be denatured by the temperature, making it difficult to make chips. was not suitable.

Solid electrolytic capacitors that use polypyrrole as the electrolyte have excellent heat resistance because the electrolyte is a polymer.
It is said to be ideal for making chips.

This polypyrrole is produced on the surface of the anode body by chemical polymerization, electrolytic polymerization, gas phase polymerization, etc. of virole. However, the mechanical strength of this polypyrrole itself is low, and it may be damaged due to mechanical stress such as twisting of the anode body as a base or external pressure.

When a general chip-shaped electronic component is surface mounted on a printed circuit board, it is transferred from a supply source and mounted using a jig such as a suction nozzle. At this time, it is said that about 1 kg of excess weight is applied to the component body due to the pressure of the suction nozzle. Ordinary electronic components can withstand this level of overload due to their exterior resin, etc., but if the electrolyte layer is made of polypyrrole, which has poor mechanical strength, and is made thinner to achieve miniaturization, the polypyrrole layer will absorb There is a risk of damage due to the pressure of the nozzle.

Furthermore, the properties of polypyrrole vary depending on moisture. Therefore, an exterior structure with improved 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 achieve an external dimension comparable to that of a ceramic capacitor.

An object of the present invention is to create a highly reliable chip that has sufficient rigidity as a chip-shaped electronic component and will not be damaged even when an electrolyte layer with weak mechanical strength is mounted on a printed circuit board. The purpose of the present invention is to provide solid electrolytic capacitors.

[Means to solve the problem]

The present invention provides a solid electrolytic capacitor in which an anode body on which an oxide film layer, an electrolyte layer, and a conductive layer are sequentially formed is arranged so that the conductive layers of the anode body are in contact with both sides of a strip-shaped cathode body. At least one of the plurality of anode bodies arranged on both sides of the anode body is characterized in that at least one of the plurality of anode bodies arranged on both sides is a frame body having a continuous protrusion formed on the outer periphery.

Further, a feature is that the cathode body, which is sandwiched between the anode bodies on both sides, is led out to the outside through a notch provided in a part of the frame-shaped anode body.

[Function] As shown in the drawings, in the present invention, the mechanically fragile electrolyte layer 3, for example, a polypyrrole layer, is sandwiched between the strong anode body 1a, at least one of which is formed into a frame shape, so that the electrolyte In addition to being able to protect the layer 3 from mechanical stress and atmospheric moisture, it is also possible to form a thin exterior resin layer on its outer surface. Therefore, the two demands of reducing the size of the part while improving the mechanical strength of the part itself can be met at the same time.

In addition, as another means, a notch 16 is provided in a part of the frame-shaped anode body 13, and the cathode body is led out through this notch 16, so that the portion where the conductive layer and the electrolyte layer are exposed can be minimized. At the same time, it becomes easy to cover this exposed portion with the exterior resin.

〔Example〕

Next, embodiments 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 invention, and FIG. 2 is a sectional view thereof. FIG. 3 is a perspective view showing an anode body used in the example, FIG. 4 is a conceptual diagram illustrating the process of forming an electrolyte layer, etc., and FIG. 5 is an exploded perspective view of the solid electrolytic capacitor according to the example. Further, FIG. 6 is a perspective view showing an anode body used in a second embodiment of the present invention.

One of the anode bodies 1 (anode body 1a) is made of aluminum or an alloy thereof in the form of a frame having a continuous protrusion 2 on the peripheral edge of a plate-like surface 8 as shown in FIG. Become. This frame-shaped anode body 1a is formed by pressing the surface of an aluminum plate or by partially etching it at selected positions.

The surface 8 of the anode body 1a surrounded by the projections 2 is subjected to a surface roughening treatment, and a dielectric oxide film layer made of aluminum oxide is formed by an electrolytic oxidation treatment. As shown in FIG. 4, this anode body 1a is immersed in a pyrrole solution containing an oxidizing agent to form a pyrrole thin film by chemical polymerization, and then placed in an electrolytic solution for electrolytic polymerization in which pyrrole is dissolved. An electrolyte layer 3 made of a polypyrrole layer with a thickness of several microns to several tens of microns is selectively generated on the surface of the anode body 1a, particularly on the surface 8 surrounded by the protrusions 2, by immersing it in water and applying a voltage. (Figure 4(b)
).

Further, a conductive layer 4 is screen printed on the surface of the electrolyte layer 3 (FIG. 4(C)). The conductive layer 4 may have 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.

Further, as shown in FIG. 5, the cathode body 5 is made of band-shaped aluminum or an alloy thereof, and in this embodiment, it has a wide electrode part 9 and a narrow terminal part 10 provided at the end thereof. Consisting of

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

As shown in FIG. 5, these frame-shaped anode body 1a, cathode body 5, and plate-shaped anode body 1b have conductive layers 4.12 of both anode bodies 1a, 1b mutually disposed on both sides of cathode body 5. The solid electrolytic capacitors are stacked in such a way that they are placed in contact with each other to form a solid electrolytic capacitor as shown in FIG.

Further, the anode terminal 6 shown in FIG. 1 is connected to one or both end faces of the anode body 1 by ultrasonic welding, laser welding, or the like.

Note that the terminal portion 10 of the cathode body 5 protrudes outward from the end surface of the anode body 1, as shown in FIG.
The gap between 0 and the anode body 1 is sealed with 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 l. Good too.

In such a solid electrolytic capacitor, as shown in FIG. 2, the cathode body 5 is sandwiched between multiple electrolyte layers via a conductive layer, so the connection structure is simple and the cathode body When 5 is formed of a lead frame, mass productivity is improved. In addition, as in the conventional case, the conductive layer and the cathode body 5
Since there is no longer a need to directly coat the connecting part with resin, it is now possible to coat the resin with methods such as molding and injection in addition to the conventional resin sealing such as botting, which improves the appearance. Dimensional accuracy is improved, polarity marking on the exterior is easy and high quality, and the resin coating process itself is simplified.

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 external mechanical stress.

Regarding the sealing of the electrolyte layer itself, the protrusion 2 formed at the peripheral end of at least one of the anode bodies 1a seals the electrolyte layer, and only the part from which the terminal part 1o of the cathode body 5 protrudes is sealed with a synthetic resin 7 or the like. By sealing it with air, you can block out the outside air. Therefore, the overall external dimensions can be further reduced.

In the embodiment, the cathode body 5 is made of a solderable metal such as copper, but a cladding material of aluminum and a solderable metal such as copper may also be used.

Further, one surface of the cathode body 5, especially the surface facing the anode body 1, is subjected to insulation treatment such as coating with resin, and the cathode body 5 is bent.
It is also possible to bring it into close contact with the anode body l.

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

In this embodiment, the anode body 13 disposed on both sides of the cathode body (not shown) has a continuous protrusion 14 formed at its peripheral end as shown in FIG. 6, and a notch in a part thereof. 16 is used. This anode body 1
An oxide film layer, an electrolyte layer, and a conductive layer are formed on the surface 15 surrounded by the protrusions 14 of No. 3. The cathode body (not shown) is sandwiched between the anode body 13 from both sides as in the first embodiment, and the anode body 13 has terminal portions arranged on both sides.
It is led out from the notch 16 of No. 3. Also, the anode body 13
The protrusions 14 that come into contact with each other are welded using means such as ultrasonic welding.

In this embodiment, anode bodies 13 are arranged on both sides of the cathode body.
Both have protrusions 14 formed on their peripheral edges, and are welded by means such as ultrasonic welding. You can get an electrolytic capacitor.

[Effects of the Invention] As described above, the present invention provides an anode body on which an oxide film layer, an electrolyte layer, and a conductive layer are sequentially formed on the surface, so that the conductive layer of the anode body is in contact with both sides of a strip-shaped cathode body. In the arranged solid electrolytic capacitor, at least one of the plurality of anode bodies arranged on both sides of the cathode body is a frame body having a continuous protrusion formed on the outer periphery. The mechanical stress caused by this is suppressed by the anode body. Therefore, the electrolyte layer will not be damaged even by the pressure of the suction nozzle during the automatic mounting process, making it possible to obtain a solid electrolytic capacitor with high reliability. This allows for a larger capacity.

Furthermore, since a frame-shaped anode body is disposed on at least one side of the exterior, both upper and lower surfaces and side surfaces thereof are surrounded by strong aluminum, improving the accuracy of external dimensions. Therefore, the positioning process during automatic mounting on the printed A board becomes accurate and simple, and printing of ratings, polarity, etc. becomes easy.

Further, the cathode body is sandwiched between an electrolyte layer formed on the anode body and a conductive layer, and is drawn out as it is.

Therefore, by simply bending the externally protruding cathode body along the outer surface of the anode body without connecting it to other external connection terminals, we manufacture solid electrolytic capacitors that can be surface mounted on printed circuit boards. can do.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a solid electrolytic capacitor according to an embodiment of the invention, and FIG. 2 is a sectional view thereof. FIG. 3 is a perspective view showing an anode body used in the example, FIG. 4 is a conceptual diagram illustrating the process of forming an electrolyte layer, etc., and FIG. 5 is an exploded perspective view of the solid electrolytic capacitor according to the example. Further, FIG. 6 is a perspective view showing an anode body used in a second embodiment of the present invention. 1.13... Anode body, 3... Electrolyte layer, 5... Cathode body, 7... Synthetic resin, 9... Electrode part, 2.14... Protrusion part, 4.12. ...Conductive layer, 6...Anode terminal, 8.15..."Anode body surface, 10...Terminal part, Fig. 1, Fig. 1b (Anode body) 11...Resist layer, 16. ...Notch.

Claims (2)

[Claims] (1) In a solid electrolytic capacitor, an anode body on which an oxide film layer, a solid electrolyte layer, and a conductive layer are sequentially formed is disposed such that the conductive layer of the anode body is in contact with both sides of a strip-shaped cathode body. A solid electrolytic capacitor, wherein at least one of the plurality of anode bodies disposed on both sides of the solid electrolytic capacitor is a frame body having a continuous protrusion formed on the outer periphery. (2) The solid electrolytic capacitor according to claim 1, wherein the cathode body sandwiched between the anode bodies on both sides is led out from a notch provided in a part of the frame-shaped anode body.