JPH07130215A - Compound dielectric film and capacitor - Google Patents

Abstract

PURPOSE:To increase electrostatic capacitance so as to provide miniaturization by connecting a capacitor, in which a film member serves as a dielectric, in parallel to a capacitor in which a packing material having a dielectric constant higher than that of the film member serves as a dielectric. CONSTITUTION:A compound dielectric film 10 is mainly composed of a tape- shaped film member 12 of synthetic resin of polyethylene terephthalate or the like. Many through holes 14 are provided in the film 12, to bury a packing substance 16 in the hole 14. The packing substance 16, mainly composed of Al23 or the like, is a substance of adding a binder of epoxy or the like. In one surface of the film 10, a pair of metalized films 20, providing an Al electrode film 20 with a margin part 18 left, are overlap wound, so as to position the margin part 18 in an opposite side, to obtain a capacitive element 24. After flattening by heat, an external electrode 26 of lead or the like is provided to complete a capacitor 32 by mounting a lead 30 with a solder 28, and an insulating outer package is applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite dielectric film suitable as a dielectric for a capacitor and a capacitor formed by laminating and winding the film.

[0002]

2. Description of the Related Art Conventionally, as a capacitor using a plastic film as a dielectric, for example, on a surface of a pair of film members made of polyester, polypropylene or the like,
A metallized film is formed by vapor-depositing aluminum or the like in a strip shape, leaving a margin portion at one end, respectively. It is known that an electrode material such as lead, tin or zinc is thermally sprayed to form an external electrode for extraction, and an appropriate outer lead terminal is connected to the external electrode for insulation. The capacitor using this metallized film has an advantage that it has excellent self-healing property for recovering the insulating property again even if a partial dielectric breakdown occurs in the film. There is also a type in which a pair of plastic films and a metal foil are alternately laminated and wound instead of forming a metallized film by depositing aluminum or the like on the plastic film.

[0003]

By the way, in recent years, along with the miniaturization and high-density mounting of electronic devices, capacitors incorporated therein have been made as compact as possible while ensuring a predetermined capacitance. Is required to do. In order for the plastic film capacitor to meet such a request, it is considered that the thickness of the plastic film is first reduced. However, if the film is made too thin, the tensile strength will decrease and the film may be cut when it is wound to form a capacitor element. Therefore, this has a certain limit. It is also conceivable that the dielectric film itself is made of a substance having a relatively high dielectric constant, and the amount used is reduced. However, a capacitor element using only a substance having a relatively high dielectric constant as a dielectric has a problem that electrical characteristics such as dielectric loss tangent and withstand voltage are inferior.

The present invention has been made in view of the above-mentioned problems of the prior art, and its object is to use a plastic film having a normal thickness and material as a main component, and therefore to be similar to the conventional art. An object of the present invention is to realize a composite dielectric film that enables miniaturization of a capacitor having a certain electrostatic capacity while maintaining tensile strength and various electrical characteristics. Another object is to realize a capacitor formed by using such a composite dielectric film.

[0005]

In order to achieve the above object, a composite dielectric film according to the present invention comprises a plastic film member, a large number of through holes formed in the film member, and the through holes. Comprising an embedded filling material,
It is characterized in that the filling material is composed of a material having a higher dielectric constant than that of the material forming the film member. As the above-mentioned filling substance, for example, a substance mainly containing a high dielectric constant substance such as aluminum oxide, titanium oxide, barium titanate or the like is applicable.

The capacitor according to the present invention comprises a plurality of composite dielectrics formed by filling a large number of through holes formed in a plastic film member with a filling material having a dielectric constant higher than that of the material forming the film member. A metallized film formed by depositing an electrode metal on each surface of the body film, and the external electrodes for extraction are formed on both end surfaces of a capacitor element formed by winding the metallized film. .

Another capacitor according to the present invention is formed by embedding a filling substance having a higher dielectric constant than a substance forming the film member in a large number of through holes formed in the plastic film member. It is characterized in that a plurality of composite dielectric films and a plurality of metal foils are alternately laminated and wound, and external electrodes for taking out are formed on both end faces of a capacitor element formed by winding the same.

[0008]

In the capacitor formed by using the above composite dielectric film, it is as if a capacitor using a film member as a dielectric and a capacitor using a filling material having a higher dielectric constant than the film member as a dielectric are connected in parallel. Therefore, the capacitance as a whole can be increased. As a result, the same capacitance can be realized with a smaller size.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiments. FIG. 1 is a plan view showing a part of a composite dielectric film according to the present invention.
Tape-shaped film member made of synthetic resin such as polyethylene terephthalate, polypropylene or polyamide
It is mainly composed of 12. As shown in FIG. 2, a large number of through holes 14 are formed in the film member 12, and as shown in FIG.
Is embedded.

The diameter of each of the through holes 14 is about 1 mm, and the distribution density thereof is about several hundreds of thousands to several millions / m ² . The through holes 14 are formed, for example, by pressing a large number of heated fine needles against the film member 12 or by pressing. The filling material 16 is a film member.
It is composed of a substance having a dielectric constant higher than 12, such as aluminum oxide (dielectric constant: several tens) and titanium oxide (dielectric constant:
(10) or a high dielectric constant material such as barium titanate (dielectric constant: 10,000), and a suitable binder such as epoxy is added thereto. Incidentally, the dielectric constant of polyethylene terephthalate exemplified as the raw material of the film member 12 is “3.2”, the dielectric constant of polypropylene is “2”, and the dielectric constant of polyamide is “4”, and all of them are included in the filling substance 16. It is extremely low as compared with the dielectric constant of the high dielectric constant material.

The filling substance 16 embedded in each through hole 14 is fixed to the through hole 14 via the binder contained in the filling substance 16. For example, the mixed substance of the high dielectric constant material and the binder is stored in advance in a microcapsule smaller than the hole diameter of the through hole 14, and the microcapsule is inside the through hole 14 of the film member 12. After filling in, to crush the microcapsules by applying pressure to the film member 12,
It is realized by leaking the internal binder into the through hole 14.

FIG. 4 shows a manufacturing process of a capacitor using the above composite dielectric film 10. That is,
On one side of the composite dielectric film 10, a pair of metallized films 22 having a metal film 20 as an electrode metal formed by vapor-depositing aluminum, zinc, or the like, leaving a margin part 18, are provided on the opposite sides of the margin parts 18. The capacitor element 24 is formed by stacking them so that they are arranged and winding them by a winder (not shown). After flattening the capacitor element 24 by hot pressing, as shown in FIG. 5, lead, tin,
An external electrode 26 for extraction is formed by spraying an electrode material such as zinc, and a lead terminal 30 is formed on the external electrode 26 via a solder 28.
The capacitor 32 is completed by connecting. Although not shown in the drawing, it is desirable that the capacitor 32 be provided with a suitable insulating exterior such as a resin mold.

In the above, an example in which the composite dielectric film 10 is formed of the metallized film 22 has been shown, but the invention is not limited to this. That is, a plurality of composite dielectric films 10 and metal foils may be alternately superposed and wound to form a capacitor element.

[0014]

In the capacitor formed by using the composite dielectric film according to the present invention, a capacitor having a film member as a dielectric and a capacitor having a filling material having a higher dielectric constant than that of the film member as a dielectric are used. Since they are connected in parallel, the overall capacitance can be increased. As a result, the same capacitance can be realized in a smaller size as compared with the case where the conventional plastic film is used as the dielectric.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a part of a composite dielectric film according to the present invention.

FIG. 2 is an enlarged cross-sectional view showing a part of a film member related to the composite dielectric film.

FIG. 3 is an enlarged cross-sectional view showing a part of the composite dielectric film.

FIG. 4 is a schematic perspective view showing a process of forming a capacitor using the composite dielectric film.

FIG. 5 is a schematic perspective view showing a capacitor formed using the composite dielectric film.

[Explanation of symbols]

 10 Composite Dielectric Film 12 Film Member 14 Through Hole 16 Filling Material 20 Metal Film (Electrode Metal) 24 Capacitor Element 32 Capacitor

Claims (4)

[Claims] 1. A plastic film member, a large number of through-holes formed in the film member, and a filling substance embedded in the through-holes, wherein the filling substance comprises the film member. A composite dielectric film comprising a material having a higher dielectric constant than that of the constituent material. 2. The composite dielectric film according to claim 1, wherein the filling substance is made of a substance containing at least one of aluminum oxide, titanium oxide and barium titanate. 3. One surface of a plurality of composite dielectric films obtained by embedding a filling substance having a higher dielectric constant than a substance forming the film member into a large number of through holes formed in the plastic film member. A capacitor characterized in that a metallized film formed by applying electrode metal to each other is superposed and wound, and external electrodes for taking out are formed on both end faces of a capacitor element formed by winding the metalized film. 4. A plurality of composite dielectric films obtained by embedding a filling substance having a higher dielectric constant than a substance forming the film member in a large number of through holes formed in the plastic film member, and a plurality of composite dielectric films. Alternately stack with the metal foil of
A capacitor characterized in that external electrodes for taking out are formed on both end faces of a capacitor element formed by winding this.