JP2000036430A - High dielectric film and manufacture of capacitor using film thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain more excellent performance by making the thickness of a high dielectric film and the thickness of plate-shaped oxide particles approximately equal. SOLUTION: A high dielectric film is constituted with the plate-shaped metal oxide particles having the dielectric constant and a heat-sensitive binder as the essential components. In this case, the high dielectric film 1 has the constitution wherein the plate-shaped metal oxide particles 2 having the high dielectric constant are dispersed in a heat sensitive inverter 3. A film thickness (a) of the high dielectric film 1 is constituted equal to a plate thickness (t) of the plate-shaped metal oxide particles 2. Furthermore, as the metal oxide having the high dielectric constant, the material having the main component of the perovskite expressed by the expression A1-xBxCO3 (A and B are one kind selected among Ba, Sr and Pb, C is Ti or Zr and x is 0-1) is used. It is recommendable that the dielectric constant is 500 or more at the room temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high dielectric film for forming a capacitor and a method for manufacturing a capacitor using the same.

[0002]

2. Description of the Related Art Conventionally, capacitors with lead wires (discrete components) have been widely used as capacitors used to form electric circuits. However, chip components without leads have been used as electronic devices have become lighter and thinner. It has been adopted. 2. Description of the Related Art The reduction in size and weight of electronic devices has been remarkably spread to mobile products such as mobile phones and video cameras. This trend has increasingly led to the adoption of chip capacitors. Also, a high dielectric insulating film is used in an organic dispersion type EL (electroluminescent lamp).

[0003]

In such a trend of miniaturization, the provision of a highly reliable capacitor with a smaller occupied area has been proposed. Therefore, there is a need to provide an improved capacitor even in the direction of shortening (that is, thinning), and the present invention solves these two problems. It was made to provide. Also, it is possible to provide a higher-performance insulating film for a conventional organic dispersion type EL (electroluminescent lamp).

[0004]

According to the present invention, there is provided a high dielectric film containing plate-like metal oxide particles having a high dielectric constant and a thermofunctional binder as essential components. An object of the present invention is to provide a high dielectric film which solves the conventional problem by making the thicknesses of the plate-like metal oxide particles substantially equal, thereby providing a high performance capacitor.

The metal oxide having a high dielectric constant used in the present invention is represented by the general formula A _1-x B _x CO ₃ wherein A and B are one selected from Ba, Sr and Pb;
C is Ti or Zr, x is 0-1. It is preferable to use a material having a perovskite-type metal oxide represented by the following formula as a main component and a dielectric constant at room temperature of 500 or more.

An example of a method for producing barium titanate ceramic powder will be described. TiCl ₄ aqueous solution and Ba
An equimolar mixture of an aqueous solution of Cl ₂ is made, and NH ₄ OH and (NH ₄ ) ₂ CO ₃ are added to the mixture to obtain TiCl ₄ + BaCl ₂ + 4NH ₄ OH + (NH ₄ ) ₂ CO ₃
→ Co-precipitation of TiO ₂ .2H ₂ O + BaCO _{3 is} obtained, dried and powdered, and reacted at 1000 ° C. or higher to obtain BaTiO ₃ . Those coprecipitated not as carbonates but as oxalates have also been put to practical use.

[0007] If the firing temperature is high, the dielectric constant increases,
Generally, the particle size increases, so that the firing temperature and the firing time are adjusted according to the required characteristics of the capacitor to obtain a powder having a desired particle size. In the nearly pure barium titanate, the value of epsilon _r in the vicinity of room temperature is 1500 to 1700, the temperature coefficient of the epsilon _r is over 150 ppm / ° C. and less. In order to make this a higher dielectric constant, SrTiO ₃ , CaSnO ₃ , BaSn
By adding an additive (shifter) for lowering the Curie temperature of BaTiO ₃ to near room temperature, such as O ₃ and BaZrO ₃ , the value of ε _r near room temperature can be reduced to 10,000 to 20.
000. However, as it is, the dielectric constant is large, but its temperature dependence is also large.
At 0 to 80 ° C., it becomes −80 to + 30% of the reference value (20 ° C.).

In order to improve the temperature characteristics, C
ATiO _3, MgTiO additives such as ₃ (Depuresa) was added, the reference value of change in dielectric constant at over 20 to 80 ° C. Instead of little smaller and 3,000 to 7,000 values of epsilon _r (20
° C) within ± 10% (Noboru Ichinose, Tadashi Shiozaki, Electroceramics, p.10
1, Gihodo Publishing (1984)) is known. Also in the present invention, a material obtained by co-precipitating a shifter or a depressor component in the synthesis reaction of BaTiO ₃ and adjusting the dielectric properties can be used as a sintering material.

[0009] These high dielectric sintering powders are commercially available as materials for multilayer capacitors and can be easily obtained. For example, DuPont sells 5540 and 5530 as Y5U lead relaxer types under the trade name of 5516 as X7S titanium type. Ε after calcination is about 6000 for the former and about 2000 for the latter, and both can be mixed to obtain an intermediate ε between them. Also,
Similarly, an acrylic binder polymer solution 5200 is commercially available from DuPont as a binder for a dielectric slurry, and the high dielectric powder is blended with the binder solution to form a slurry, which is cast on a heat-resistant substrate and dried. (Green sheet), and further performing binder removal treatment at around 400 ° C. and then baking at a high temperature of 850 ° C. or higher, for example, 1300 to 1400 ° C., can obtain a high dielectric plate material having an arbitrary thickness.

The plate-like metal oxide particles having a high dielectric constant used in the present invention can be produced by the following method. 1) A high dielectric slurry is printed on a heat resistant substrate in a fine pattern, dried, debindered, and fired. 2) A high-dielectric slurry is solid-printed or cast on a heat-resistant substrate, and a dried green sheet is punched out, cut into small pieces by a method such as cutting, debinding and firing. 3) A high dielectric slurry is solid-printed or cast on a heat-resistant substrate, and the dried and debindered sheet is cut into small pieces by a method such as pulverization and fired. 4) A high-dielectric slurry is solid-printed or cast on a heat-resistant substrate, dried, debindered, and calcined. In the above 2) to 4), a heat-resistant dielectric metal is vapor-deposited on one or both sides by means such as vapor deposition before the green sheet after drying, the sheet after debinding, or the sheet after firing is subdivided. It can also be formed as a thin film by means such as sputtering or sputtering. In the method 4), a conductive film can be formed by applying a conductive paste using an organic binder.

The high dielectric film of the present invention is a high dielectric film containing plate-like metal oxide particles having a dielectric constant and a heat-sensitive binder as essential components. The metal oxide particles have a structure in which the film thicknesses are substantially equal. FIG. 1 schematically shows a cross section of the high dielectric film of the present invention. Here, the high dielectric film 1 has a structure in which plate-like metal oxide particles 2 having a high dielectric constant are dispersed in a thermosensitive binder 3, and the film thickness d of the high dielectric film 1 is high. It is configured to be equal to the plate thickness t of the plate-like metal oxide particles 2 having a dielectric constant. Of the present invention,
The condition that the high dielectric film 1 has a structure in which the film thickness d of the high dielectric film is equal to the film thickness t of the plate metal oxide particles is that the plate metal oxide particles 2 having a high dielectric constant This is because the electrode material is brought into direct contact with the electrode material.
It is described as follows.

The capacitance C of a capacitor is given by multiplying the dielectric constant ε of the capacitor by the area A of the capacitor and dividing the result by the thickness d of the capacitor. Here, as shown in FIG. 2A, a capacitor (a) having a structure in which a dielectric having a high dielectric constant ε _c is dispersed in a binder having a low dielectric constant ε _B and a high dielectric constant dielectric with a rate epsilon _c is (thickness t), dispersed in a binder exhibiting low dielectric constant epsilon _B, consider the same thickness d and the thickness t condenser (b). This equivalent circuit is as shown in (2), in (a) is a capacitor C _B of the capacitor C _c and the small capacity of the large capacity arranged in series, the capacitor C _c and the small capacity of the large capacity in (b) condenser C _B are arranged in parallel. Therefore, even if the volume ratio p of the dielectric having the high dielectric constant ε _c is the same, the capacitance of (a) is small and that of (b) is large.

[0013] Incidentally, the capacitance in the case of (b) _{is, C = C c · p +} · C B (1-p) = {ε c p · A / d} + {ε B (1-p) · A / d｝ Generally, the dielectric constant ε of the material used for the binder
_B is low and has a relationship of ε _c >> ε _B. Therefore, it can be seen that the second term is negligible in (b), whereas in (a) it is directly affected by ε _B and gives only a very low capacitance. From this equation, the capacitance of the high dielectric film of the present invention is mainly determined by the dielectric constant ε _c of the high dielectric used and its content p and the film thickness d of the high dielectric film.
It is apparent that the thickness is determined by the (thickness t of the plate-like metal oxide particles having a high dielectric constant) and the size (area) of the high dielectric film.

In the present invention, the dielectric constant ε _c of the high dielectric substance is preferably about 500 to 20,000. If it is lower than this, it is difficult to obtain a necessary and sufficient capacitance. The plate-like metal oxide powder having a high dielectric constant used in the present invention is a plate-like metal having a thickness of t5 to 100 μm and has a polygonal shape such as a circular shape, a triangular shape, a quadrangular shape, or an irregular shape. Although a regular shape can be used, in general, a circular or square shape is preferable from the viewpoint of easy production of the plate-like body and uniformity of filling of the plate-like metal oxide fine particles when formed into a film. Here, the size of the plate-like metal oxide fine particles, as the diameter or the length L of the long axis, is preferably 2 to 1000 times the thickness t, and generally 50 μm to several mm.
Needless to say, these sizes differ depending on the application of the high dielectric film. When used as a capacitor, a relatively thin and small size is used, for example, in a high dielectric insulating material for EL. A relatively large size can be used. In the present invention,
The ratio p of the high dielectric substance can be arbitrarily selected depending on the application and the required capacitance, but is generally 20 to 78.5% by volume.
Is preferable. If it is lower than 20%, it is difficult to secure the required capacitance. If it is more than 78.5%, the area of the binder is too small, and the adhesion between the high dielectric film and a different material such as an electrode material is insufficient. This is not preferred because of the tendency to be made.

The heat-sensitive binder of the present invention is a binder which exhibits adhesiveness by heat, and mainly contains a resin selected from a hot-melt thermoplastic resin and a B-stageable thermosetting resin. Binder. Here, the hot-melt thermoplastic resin has poor adhesiveness at room temperature, but exhibits adhesiveness when heated or heated under pressure.Polyvinyl acetate resin, polyvinyl butyral resin, acrylic resin, It contains polyamide resin, ethylene-vinyl acetate resin, ethylene-acrylate resin, polyester resin, cellulose resin, etc. as main components, and if necessary, rosin or rosin derivative, petroleum resin, rubber component, etc. is there. In addition, those having photoreactivity in addition to heat sensitivity can be used as the binder. Generally, a combination of a photoreactive oligomer, a monomer and a photopolymerization initiator is used to impart photoreactivity.

The cured state of the thermosetting resin is A stage,
It is divided into B stage and C stage. The A stage is also uncured and soluble in the solvent and fusible, the B stage is semi-cured and swells in the solvent but does not dissolve and cannot be melted by heating and remains in a rubbery state. The C stage is completely This is the final state of insolubility and infusibility. As the binder of the present invention, a thermosetting resin that maintains a long B-stage state is preferable. One example is a system for curing an epoxy resin with an aromatic amine.

The resin used as a main component of the heat-sensitive binder generally has a dielectric constant of 2.5 to 4.0.
And low. Therefore, to increase the dielectric constant of the binder,
A polymer having a higher dielectric constant (for example, SDP-E (ε: 1 by Sumitomo Chemical) as long as heat sensitivity and adhesiveness are not impaired.
5 <) and Shin-Etsu Chemical's cyanoresin CR series (ε: 1
6 <) or highly dielectric liquid (for example, SDP-S of Sumitomo Chemical)
(Ε: 40 <) can also be added. In addition, various additives such as a diluent and an antioxidant, a thermal polymerization inhibitor, a leveling agent, a surface modifier, and a defoaming agent for diluting these heat-sensitive binders with a suitable diluent can also be added. .

As a method of manufacturing the high dielectric film 1 in the present invention, several methods described below can be adopted. However, as long as the structure shown in FIG. 1 is obtained, the method is not limited to the following method. Absent. 1) Plate-like metal oxide particles having a high dielectric constant are dispersed in an organic solvent solution of a heat-sensitive binder, coated on a support such as a PET film with a coating tool such as a doctor blade, and sufficiently settled. Then dry or B-stage,
Further, the surface is smoothed by means such as buffing so that the film thickness becomes equal to the plate thickness of the plate-like metal oxide particles. 2) While vibrating a support film such as PET, plate-like metal oxide particles having a high dielectric constant are sprinkled on the support film to form a state in which one layer of the plate-like metal oxide particles is arranged. An organic solvent solution of a responsive binder is sprayed and dried or B-staged to fill the binder between the plate-like metal oxide particles and the binder on the plate-like metal oxide particles is removed by means such as buffing. Then, the film thickness is made equal to the plate thickness of the plate-like metal oxide particles.

3) A film of a heat-sensitive binder having a specified thickness is previously formed on a support such as PET, and plate-like metal oxide particles having a high dielectric constant are sprinkled on the surface of the film to form the plate-like metal oxide. After forming a state in which one layer of material particles are lined up, by applying pressure and heating using a hot press, the heat-sensitive binder existing under the plate-like metal oxide particles is removed, and the plate-like metal oxide is removed. By filling gaps between the object particles, the film thickness is made equal to the plate thickness of the plate-like metal oxide particles. Instead of buffing, a method of removing unnecessary binders by laser irradiation or plasma asher can also be adopted. In the present invention, a capacitor can be manufactured by cutting the high dielectric film of the present invention into a desired size and forming electrodes on both surfaces thereof.

Here, as a capacitor electrode, generally, a lower electrode obtained by etching a copper foil is used.
The following materials and construction methods are adopted for the upper electrode. Of course, it is also possible to form the upper and lower electrodes by the following materials and methods. 1) A metal powder paste of silver, Ni, Cu or the like is screen-printed in a predetermined shape. 2) The photosensitive conductive metal paste is patterned by a photolithography technique. 3) After forming a conductive metal thin film by vapor deposition, sputtering, or the like, the metal is patterned by photolithography. 4) A conductive tape in which a conductive adhesive is applied to a metal thin film is used. As a screen-printable conductive metal paste, there is a commercially available paste obtained by mixing a conductive metal powder with a thermosetting resin or a thermoplastic resin. For example,
Examples include DM4030 series and DM5030 manufactured by Daimat Corporation.

Further, as the photosensitive conductive metal paste,
UV conductive paste containing silver as described in the literature (Photopolymer Roundtable, Photopolymer Handbook, p510 Industrial Research Committee (1989)) (Note 1)
Can be shown as an example. ─────────────────────────────────── Note 1) Bisphenol A epoxy acrylate 60 parts 2-hydroxyethyl methacrylate 40 Part 2-ethylanthraquinone 5 parts azoisobutyronitrile 4 parts hydroquinone monomethyl ether 0.2 parts silver powder (average particle size 1.2 μm) 436.8 parts ────────────────────

When the present invention is applied to an organic dispersion type EL, the high dielectric film of the present invention can be coated on the surface of an aluminum sheet serving as a back electrode or a sheet having a carbon electrode formed on a substrate such as PET. The pieces cut to size are attached to each other, and the surface is further coated with a phosphor ink to be a light emitting layer.
Next, it can be manufactured by printing a current collecting electrode (bus bar) and then crimping PET with ITO.

(Action) According to the present invention, in a high dielectric film containing plate-like metal oxide particles having a high dielectric constant and a heat-sensitive binder as essential components, the film thickness of the high dielectric film and By making the thicknesses of the plate-like metal oxide particles substantially equal, a high dielectric film that solves the conventional problems is provided, and thereby a high-performance capacitor is provided.

[0024]

EXAMPLES The method for producing a high dielectric film according to the present invention, its characteristics and examples of its use are shown in the following examples. It goes without saying that the invention is not limited to these examples.

(Example 1) By a conventional method, ceramic dielectric powder 5540 for a film thickness capacitor (DuPont product)
And an acrylic binder polymer solution 5200 (DuPont product) for dielectric slurry were mixed and screen-printed on an alumina substrate to a diameter of about 200 μm after firing.
m, and a pattern was printed so as to have a thickness of 40 μm. After drying at 120 ° C. for 30 minutes, a binder removal treatment was performed at 400 ° C. for 2 hours, and then a high-temperature baking was performed at 1200 ° C. for 2 hours to obtain a disc-shaped high dielectric ceramic powder. This was spread evenly on a PET film to which vibration was applied (the area occupied by the disc-shaped high dielectric ceramic powder in this state was about 60%), the vibration was stopped, and bisphenol was applied using a spray coating machine. A type epoxy resin (Epicoat 828, oiled shell epoxy product) 100
A solution prepared by diluting 35 parts by weight of an aromatic amine-based curing agent (Kayahard A-A, Nippon Kayaku product) with methyl ethyl ketone as a solvent was applied. When the binder was dried, the binder film thickness in a portion where the disc-shaped high dielectric ceramic powder was not present was 42 μm. 80 ℃ 2
After curing for an hour, the epoxy binder was B-staged. The pencil hardness in this state was H, and it could be easily polished with a polishing roll (trade name: Legato) of Otsuka brush, and the thickness of the binder could be made equal to the thickness of the disc-shaped ceramic plate. This high dielectric film with a support was cut into a slitter 10 mm width to form a tape.

On the other hand, a substrate was prepared by etching a copper foil of a glass epoxy substrate with a copper foil as shown in FIG.
On this substrate, as shown in FIG.
Attach a high dielectric film cut to 0 mm,
The PET of the support was peeled off by pressing at 0 ° C. Further, as shown in FIG.
A conductive silver paste DM4030HT manufactured by Daimat Co., Ltd. was printed and cured to a length of 30 mm (the area overlapping with the copper foil as the lower electrode was 5 × 10 mm and 50 mm ² ). The capacitance of the capacitor thus produced was about 0.04 μF.

(Example 2) Ceramic dielectric powder 5530 (DuPont product) for thick film capacitors and acrylic binder polymer solution 5200 for dielectric slurry
(DuPont product) was mixed, cast on an alumina substrate, and solid-coated so that the film thickness after firing was 25 μm. After drying at 120 ° C. for 30 minutes,
After performing binder removal treatment in 2 hours, it was cut into about 1 mm square with a diamond cutter, and then fired at 1200 ° C. for 2 hours at a high temperature to obtain a square plate-like high dielectric ceramic powder. This powder is spread evenly on an aluminum sheet serving as a back electrode, and a cyano resin CR-S (Shin-Etsu Chemical Co., Ltd.) N, N'-dimethylformamide (DM), which is a thermoplastic resin and has a dielectric constant of around 18,
F) A 10% solution was uniformly applied, and then polished with a polishing roll (trade name: Legato) of Otsuka brush in the same manner as in Example 1 to a film thickness of 25 μm. Hereinafter, after forming a phosphor-containing light-emitting layer, a current collector (bus bar), and a transparent electrode-attached PET film on the surface by a conventional method,
EL integrated by pressing with a rubber roll laminator
A device was created. The lamination conditions were as follows: roller temperature 150 ° C., pressure 10 kg / cm, speed 10 cm /
Minutes. Thereafter, a three-layer sandwich was sandwiched between the transparent electrode side and the back electrode side of the EL element with a moisture-proof film coated with an adhesive, and sealed with a laminator.
The luminance of the EL element manufactured by such a method was remarkably improved as compared with that of the conventional manufacturing method.

[0028]

According to the high dielectric film of the present invention, the real substrate can be made lighter, thinner and shorter, and a highly reliable capacitor with a small occupying area is provided. In addition, the high performance of a high dielectric insulating film for an organic dispersion type EL (electroluminescent lamp) has been realized.

[Brief description of the drawings]

FIG. 1 is a perspective view of a sectional view of a high dielectric film of the present invention.

FIG. 2 is a cross-sectional view of a capacitor using the high dielectric film of the present invention. (A) It is sectional drawing of the thickness of the capacitor | condenser of the structure which the dielectric material having a dielectric constant of this invention was disperse | distributed in the binder which shows a dielectric constant. (B) is a cross-sectional view of a capacitor having the same thickness as the capacitor of the present invention in which the dielectric having a high dielectric constant is dispersed in a binder having a low dielectric constant. (2) It is a figure showing an equivalent circuit of the capacitor of the present invention. (A) is a diagram in which a large-capacity capacitor and a small-capacity capacitor are arranged in series. (B) A diagram in which a large-capacity capacitor and a small-capacity capacitor are arranged in parallel.

FIG. 3 is an upper view of a glass epoxy substrate with a copper foil of the present invention, and a lower view is a sectional view. (A) It is the figure which etched the copper foil on the upper part of the glass epoxy board with a copper foil of this invention. (B) It is the figure which laminated | stacked the high dielectric film of this invention on the upper part of copper foil on the glass epoxy board with copper foil of this invention. (C) A view in which a high dielectric film of the present invention is laminated on a copper foil on the glass epoxy substrate with a copper foil of the present invention, and a conductive silver paste is printed on the upper portion.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 high dielectric film 2 plate-like metal oxide particles 3 thermofunctional bander d film thickness of high dielectric film t plate thickness of plate-like metal oxide particles 4 conductive silver paste layer 5 glass epoxy substrate 6 copper foil

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Isao Moroka Inventor 251 Suwa-cho, Hachioji-shi, Tokyo F-term in Asahi Chemical Laboratory Co., Ltd. (reference) 5E082 AB03 BB10 BC39 EE03 EE23 EE24 EE26 EE27 EE35 EE41 FF14 FG06 FG26 FG27 FG34 FG36 FG46 FG54 FG56 KK01 LL01 MM22 MM24 PP09

Claims (6)

[Claims] 1. A high-dielectric film comprising plate-like metal oxide particles having a high dielectric constant and a thermofunctional binder as essential components, wherein the film thickness of the high-dielectric film and the thickness of the plate-like metal oxide particles are A high dielectric film characterized in that the film thickness is substantially equal. 2. A high dielectric film, wherein a conductive coating is formed on one or both of the plate surfaces of the plate metal oxide particles used for the high dielectric film according to claim 1. . 3. The plate-like metal oxide used for the high dielectric film according to claim 1, wherein A and B are selected from Ba, Sr, and Pb, wherein A _{1 -xB x} CO _3. C is Ti or Zr, x is 0-1. A high dielectric film comprising a perovskite-type metal oxide represented by the following formula as a main component, and having a dielectric constant at room temperature of 500 or more. 4. A heat-sensitive binder used in the high dielectric film according to claim 1, comprising a resin selected from a hot-melt thermoplastic resin and a thermosetting resin capable of being B-staged. High dielectric film characterized. 5. The high dielectric film according to claim 1,
A high dielectric film formed on a support film and provided in the form of a tape or a sheet with its surface coated with a protective film if necessary. 6. A method for manufacturing a capacitor, comprising cutting the high dielectric film according to claim 1 into a desired size and forming electrodes on both sides thereof to manufacture a capacitor.