JPH03297122A - Solid electrolytic capacitor and its manufacture - Google Patents

Abstract

PURPOSE:To realize a sufficient rigidity as a chip-shaped electronic component, to prevent an electrolyte layer whose mechanical strength is weak from being damaged and to enhance reliability by a method wherein a sheetlike resin film covering the surface excluding recessed parts are arranged at gaps of a plurality of anode bodies. CONSTITUTION:A plurality of anode bodies 1a, 1b are formed to be sheetlike; recessed parts 6 are formed partially in their surface. Since mechanically weak electrolyte layers 3 are formed in the recessed parts 6 together with conductive layers 4, they are surrounded by protruding parts 7 at the circumference, and the mechanical strength of the anode bodies 1a, 1b is enhanced. Consequently, it is possible to prevent the layers 3 from being damaged by a twist or the like of the individual anode bodies, and the layers 3 are shut off from the outside air by a cathode body 5 and the anode bodies 1a, 1b. Since the anode bodies 1a, 1b are bonded via a sheetlike resin layer 9, a gap by a strain is closed by the layer 9 and it is possible to prevent a bonding defect. Thereby, an electric characteristic can be maintained stably for a long term, and reliability is enhanced. When the anode bodies 1a, 1b are pressure-bonded by executing a heat treatment, a hermetically sealing property can be enhanced furthermore.

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.

[Background Art] In recent years, electronic components have been made into chips due to the demand 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. Therefore, this sealing means hinders the miniaturization of electrolytic capacitors, and although various proposals have been made for chip-type electrolytic capacitors that are based on the premise of miniaturizing the electrolytic capacitor body, for example, the height dimension from the printed circuit board The limit is about 10an to 4mm, and it has been extremely difficult to realize a chip-type electrolytic capacitor with an external dimension of about 1mm to 3mm, 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 and the like, and if tantalum is used for the anode body, the cost will be high.

[Problem to be solved by the invention]

By the way, in recent years tetracyanoquinodimethane (TCNQ)
, solid electrolytic capacitors using organic conductive compounds such as polypyrrole have been proposed.

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.

In particular, polypyrrole has high conductivity, and solid electrolytic capacitors using polypyrrole as an electrolyte are said to be ideal for chip production 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 such as twisting of the anode body.

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 make the external dimensions comparable to those of the ceramic capacitor.

An object of the present invention is to provide a solid electrolytic capacitor with high reliability, which has sufficient rigidity as a chip-shaped electronic component and will not be damaged even with an electrolyte layer having weak mechanical strength. be.

[Means to solve the problem]

The present invention provides a solid electrolytic capacitor in which a plurality of anode bodies each having a recess in which an oxide film layer, an electrolyte layer, and a conductive layer are sequentially formed are joined to both sides of a strip-shaped cathode body so that the conductive layers face each other. It is characterized in that a plurality of anode bodies are joined via a resin layer disposed on a part of the surface of at least one anode body or a resin layer made of a conductive synthetic resin.

Another feature is that the resin layer is made of a sheet-like resin film that covers the surface of the anode body except for the recessed portions. Furthermore, the manufacturing method is characterized in that a sheet-like resin film is placed in the gaps between a plurality of anode bodies to cover the surface of the anode bodies except for the concave portions, and then a heat treatment is performed and the anode bodies are pressed together.

[For production]

As shown in the drawings, in the present invention, a mechanically fragile electrolyte layer 3 , for example a polypyrrole layer, is formed together with a conductive layer 4 in a recess 6 formed in a part of an anode body 1 . Therefore, the electrolyte layer 3 is surrounded by an outer periphery that forms a convex portion 7 relative to the concave portion 6, and the mechanical strength of the anode body 1 itself is also affected by the convex portion 7 formed in a portion thereof. Improve by doing. Therefore, damage to the electrolyte layer 3 due to twisting of the anode body 1 can be prevented, and the electrolyte layer 3 is isolated from the outside air by the cathode body 5 and the anode body 1.

Furthermore, although the recessed portion 6 of the anode body 1 is formed by, for example, press working, distortion of the anode body 1 due to the press process appears on the surface of the anode body 1, and the plurality of anode bodies 1a, 1b are removed from the cathode body. When bonded to both sides of anode body 1a and anode body 1
There may be a gap between the or,
In order to eliminate such inconveniences, it has been necessary to press the anode body 1 with a roller or the like to form the surface of the convex portion 7 into a flat shape.

However, in the present invention, since the plurality of anode bodies 1a, 1b are joined via the resin layer 9, the gap caused by the distortion of the anode bodies 1a, 1b is closed by the resin layer 9, and poor joining can be prevented. .

〔Example〕

Next, embodiments of the 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 partial sectional view showing its conceptual structure. Further, FIG. 3 is a perspective view showing an anode body of a solid electrolytic capacitor according to an embodiment of the present invention, and FIG. 4 is an exploded perspective view illustrating the structure of the solid electrolytic capacitor and its manufacturing method according to the embodiment.

The anode body 1 is made of a valve metal such as aluminum, and is formed into a plate shape as shown in FIG. It is formed.

The recess 6 may be formed by other means such as chemical etching.

Then, in order to enlarge the surface area of the recess 6, an etching treatment, such as an electrolysis/etching treatment, is performed to roughen the surface, and then a chemical conversion treatment is performed to form an oxide film layer on the surface of the recess 6. do. The oxide film layer is made of aluminum oxide obtained by oxidizing the surface layer of the aluminum anode body 1, and serves as a dielectric. Note that the etching treatment and the chemical conversion treatment may also be applied to the inner surface of the recess 6 as necessary, for example, to adjust the capacity.

Furthermore, the recess 6 formed in the anode body 1 is coated with a resist layer 8 that partially covers the surface thereof.

This resist layer 8 is made of a heat-resistant synthetic resin, for example, an epoxy resin, and is formed by means such as screen printing.

Then, an electrolyte layer 3 made of polypyrrole or the like is formed on the uncoated surface of the resist layer 8. The electrolyte layer 3 is formed by immersing the anode body 1 in a virol solution containing an oxidizing agent to form a virol thin film through chemical polymerization, and then immersing it in an electrolytic solution for electrolytic polymerization in which virol is dissolved and applying a voltage. The film is formed to have a thickness of several μm to several tens of μm. In addition,
No voltage is applied to the resist layer 8 on the surface of the recess 6, and no polypyrrole layer is generated.

Furthermore, conductive N4 is screen printed on the surface of the electrolyte layer 3. As a result, as shown in the conceptual structure diagram in Figure 2,
An electrolyte layer 3 and a conductive layer 4 are sequentially formed in the recesses 6 of the anode bodies 1a and 1b.

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.

The plurality of anode bodies 1a and 1b thus formed are arranged on both sides of a strip-shaped cathode body 5 made of copper or its alloy, as shown in FIG. 4, so that the conductive layers 4 of each one face each other. .

At this time, anode bodies 1a and 1 are placed in the gap between anode bodies 1a and 1b.
A sheet-like resin film 10 is disposed to cover the surface, that is, the convex parts 7, excluding the recesses 6 of b. A sheet-like material was used that was heat-fused and then solidified and bonded.

Then, in this state, the anode bodies 1a and 1b are joined together, and while being subjected to heat treatment, the anode bodies 1a and 1b are pressed from above and below. As a result, the resin film 10 is melted and solidified, and a resin layer 9 is formed in the gap between the plurality of anode bodies 1a and 1b. Furthermore, anode terminals 2 made of a solderable metal such as copper are welded to the end faces of the anode bodies 1a and 1b by means such as laser welding, thereby forming a plurality of anode bodies 1a and 1b as shown in FIG. A solid electrolytic capacitor including the resin layer 9 in the gap 1b is obtained.

In the solid electrolytic capacitor obtained in this way, the second
As shown in the figure, the electrolyte layer 3 is disposed on both sides of the cathode body 5 and is connected to sandwich the cathode body 5 via the conductive layer 4, so that the connection structure between the electrolyte layer 3 and the cathode body 5 is In addition to being simple, the electrolyte layer 3 is isolated from the outside by the anode bodies 1a and 1b, making it strong against mechanical stress from the outside.

Further, the plurality of anode bodies 1a, 1b are joined through the cathode body 5 in the conductive layer 4, and at the same time, the outer peripheral portion thereof,
That is, at the relative convex portions 7 formed by the concave portions 6, the anode bodies 1a and 1b are joined via the resin layer 9 covering the surfaces of the convex portions 7. Therefore, the internal electrolyte layer 3 can be sealed from the outside air regardless of the molding precision of the anode bodies 1a, 1b. That is, the unevenness generated on the surface of the convex portion 7 of the anode bodies 1a, 1b, the distortion of the anode bodies 1a, lb themselves, etc. are absorbed by the resin layer 9, and the bonded state of the anode bodies 1a, 1b can be maintained well. can.

Further, the lead-out portion of the cathode body 5 is covered with a resist layer 8 that partially covers the recess 6, and the end portion of the electrolyte layer 3 is shielded from the outside by the resist layer 8.

In addition, in this embodiment, the cathode body 5 and the anode terminal 2
Although a material made of a metal that can be soldered, such as copper, was used, a clad material made by joining aluminum and a metal that can be soldered, such as copper, may also be used. Alternatively, one surface of the cathode body 5, particularly the surface facing the anode body 1, may be insulated by coating with resin, and the bent cathode body 5 may be brought into close contact with the anode body 1.

Further, as another embodiment, the resin layer 9 may be made of thermoplastic synthetic resin such as polypropylene in addition to thermosetting synthetic resin such as epoxy resin.

In yet another embodiment, the resin layer 9 may be made of a conductive synthetic resin. In this case, a plurality of anode bodies 1
In addition to improving the sealing state of a and 1b, the electrical connection state is also improved, and as in the previous embodiment, a solid electrolytic structure in which a plurality of anode bodies 1a and 1b are electrically connected only by anode terminal 2 is achieved. Improved reliability compared to capacitors.

〔Effect of the invention〕

As described above, the present invention provides a plurality of anode bodies having recesses in which an oxide film layer, an electrolyte layer, and a conductive layer are sequentially formed.
In a solid electrolytic capacitor in which conductive layers are bonded to both sides of a strip-shaped cathode body so as to face each other, multiple anode bodies are bonded via a resin layer placed on a portion of the surface of one of the anode bodies. Even if the surface of the anode body becomes uneven or distorted due to pressing, etc.,
The resin layer covers these irregularities. Therefore, it is easy to seal the internal electrolyte layer from the outside air, and it is possible to prevent the electrical characteristics of the electrolyte layer from changing due to moisture, etc., so it is possible to maintain stable electrical characteristics over a long period of time. can.

Furthermore, when a plurality of anode bodies are bonded via a resin layer made of a conductive synthetic resin as the resin layer, the electrical connection between the anode bodies becomes good and reliability improves.

As yet another means, the resin layer is characterized by being made of a sheet-like resin film that covers the surface of the anode body except for the recessed portions, so that when joining a plurality of anode bodies, the sheet-like resin film is used as an anode. It can be placed in the interstices of the body to form a resin layer.

Further, as a method for manufacturing a solid electrolytic capacitor according to the present invention, a sheet-like resin film is placed between a plurality of anode bodies to cover the surface of the anode bodies except for the concave portions, and then heat treatment is performed and the anode bodies are pressed together. Because it is characterized by
The melted resin film is solidified by the heat treatment, and a resin layer can be formed in the gaps between the plurality of anode bodies, and a strong bonded state can be obtained by pressure welding, which further improves the sealing performance.

[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 partial sectional view showing its conceptual structure. Further, FIG. 3 is a perspective view showing an anode body of a solid electrolytic capacitor according to an embodiment of the present invention, and FIG. 4 is an exploded perspective view illustrating the structure of the solid electrolytic capacitor and its manufacturing method according to the embodiment. DESCRIPTION OF SYMBOLS 1... Anode body, 3... Electrolyte layer, 5... Cathode body, 7... Convex part, 9... Resin layer, 2nd... Anode terminal, 4... Conductive layer , 6... Concavity, 8... Resist layer, 10... Resin film.

Claims (4)

[Claims] (1) In a solid electrolytic capacitor, 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 bonded to both sides of a strip-shaped cathode body so that the conductive layers face each other. A solid electrolytic capacitor, characterized in that the anode bodies are joined via a resin layer disposed on a part of the surface of at least one of the anode bodies. (2) The solid electrolytic capacitor according to claim 1, wherein a conductive synthetic resin is disposed as the resin layer. (3) Claim 1 or 2, wherein the resin layer is made of a sheet-like resin film that covers the surface of the anode body except for the recessed portions.
The solid electrolytic capacitor described. (4) The solid according to claim 3, characterized in that a sheet-like resin film is placed between the plurality of anode bodies to cover the surface of the anode bodies except for the concave portions, and then heat-treated and the anode bodies are pressure-welded. Method of manufacturing electrolytic capacitors.