JPH08115849A - Laminated capacitor - Google Patents

Abstract

PURPOSE: To provide a laminated capacitor which can use a high-permeability material, which can be made thin to the same extent as a thin-film capacitor and a laminated capacitance-type capacitor and which increase an electrode area because films are laminated. CONSTITUTION: A laminated capacitor comprises at least one unit laminated body of a four-layer structure which is composed of a thermoplastic polymer film 1, of a metal thin film 2 laminated on the thermoplastic polymer film, of a semiconductor ceramic thin film 3 laminated on the metal thin film 2 and of a metal thin film 4 which is laminated on the semiconductor ceramic thin film 3 and which forms a pair with the metal thin film 2. The thermoplastic polymer film is used as a carrier, the metal thin film is formed on it, the semiconductor ceramic thin film is laminated on it, the metal thin film is laminated additionally, the unit laminated body of the four-layer structure is formed, a plurality of unit laminated bodies of this constitution are stacked, and the unit laminated bodies are pressurized and thermocompression-bonded at a temperature at which a thermoplastic polymer as a carrier material is melted.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to multilayer capacitors, and in particular to
The present invention relates to a small-sized, lightweight, large-capacity multilayer capacitor having a novel structure and a method for manufacturing the same.

[0002]

2. Description of the Related Art With the development of electronics, the number of electronic parts per unit volume of electronic equipment has increased, and the demand for smaller and lighter electronic parts has become more and more strict. Capacitors are no exception, and there is a growing demand for smaller size, larger capacity, lower cost, and higher reliability. Unlike semiconductor elements such as transistors and diodes that are related to physical phenomena at the interface, capacitors have the property that their capacitance is proportional to the electrode area. Therefore, it is not easy to achieve both large capacitance and miniaturization at the same time. However, some capacitors have been put to practical use as those that satisfy these requirements to some extent. From a technical viewpoint of increasing the capacity, (1) a high dielectric constant material such as a perovskite complex oxide typified by barium titanate is used as a dielectric material, and its powder is slurried with an organic binder or the like. It is roughly classified into three types: a multilayer ceramic capacitor formed into a film shape, laminated with an internal electrode and then sintered together, (2) an electrolytic capacitor and an electric double layer capacitor, and (3) a thin film capacitor.

[0003]

However, the monolithic ceramic capacitor is intended to have a small size and a large capacity due to an increase in the electrode area due to the adoption of a high dielectric constant material and lamination, but it is usually a high temperature of several thousand hundreds of degrees Celsius. Since it is necessary to sinter in, it is necessary to use expensive precious metals such as silver and palladium as internal electrodes, and to use a large amount of energy.
High cost due to complicated manufacturing process, and
The thickness of the dielectric layer cannot be reduced to 10 μm or less, and there is a limit to increase the capacity.

Further, the electrolytic capacitor and the electric double layer capacitor are intended to have a large capacity by maximizing the surface area of the electrode due to the unevenness of the electrode surface. In the former case, the metal surface of the electrode material such as aluminum or tantalum is used. Due to the structure that uses the anodic oxide film as the dielectric, there is no room to select the dielectric material, so it is not possible to meet the requirements of various capacitor characteristics, and the relative permittivity of these oxides is about several tens. Since it is significantly lower than the value of thousands of dielectric porcelains such as barium titanate used in ceramic capacitors, the capacitance is small despite the large electrode area,
Moreover, it has the drawback of being polar. On the other hand, the latter electric double layer capacitor can have a small volume ratio / capacitance, but is vulnerable to shocks because it contains an electrolytic solution, and has problems such as low operating voltage and the inability to increase the electrode area due to lamination. .

Further, in the thin film capacitor, by making the thickness of the electrode and the dielectric as thin as possible, the volume occupied by the dielectric is reduced, and at the same time, the capacitance per unit area is increased to increase the capacitance. The film thickness is generally several hundred nm or less. Thin film capacitors include thin films of oxides such as tantalum oxide formed by vapor phase methods such as vapor deposition and sputtering, but their dielectric constants are at most several tens, which is not sufficient to realize large capacity. .
Attempts have also been made to make thin films of high dielectric constant materials such as barium titanate by the same vapor phase method. However, the thin film formed by the vapor phase method has a relative dielectric constant of several hundreds because the ferroelectricity does not appear sufficiently, but it is much lower than the several thousand of the film thickness used in the ceramic capacitor although it is higher than that of tantalum oxide. Since the lamination technology and the thin film formation technology for a large surface area have not been developed, it is not possible to expect an increase in the electrode area, and it is the current situation that a large capacity capacitor cannot be realized only by thinning. On the other hand, there is a weir layer capacitance type semiconductor porcelain capacitor that can increase the capacitance per unit area, but this is a semiconductor of high dielectric constant porcelain material such as barium titanate and a non-ohmic conductor is formed on its surface. However, the capacitance of the potential barrier layer formed at the interface between the semiconductor and the conductor is used to increase the capacitance. However, in terms of downsizing of the entire device, it is far beyond the three types of capacitors. There is a problem that there is no. Therefore, the present invention can use a material having a high dielectric constant, which cannot be expected in an electrolytic capacitor, can make the structure of a portion forming a capacitance as thin as a thin film capacitor or a weir layer capacitance type capacitor, and can provide a multilayer ceramic capacitor. Thus, it is an object of the present invention to obtain a capacitor which can increase the electrode area by stacking layers, in particular, a capacitor having a novel structure having the advantages of a laminated ceramic capacitor and a dam layer capacitance type capacitor.

[0006]

Means for Solving the Problems As a means for achieving the above object, the present invention provides a thermoplastic polymer film, a metal thin film laminated on the thermoplastic polymer film, and a metal thin film laminated on the metal thin film. A capacitor is constituted by at least one unit laminated body having a four-layer structure composed of a semiconductor porcelain thin film and a metal thin film laminated on the semiconductor porcelain thin film and forming a pair with the metal thin film.

Therefore, according to the present invention, it is possible to obtain a multilayer capacitor in which a plurality of unit laminates having the four-layer structure are laminated and integrated.

According to the present invention, the multilayer capacitor is
A thermoplastic polymer film is used as a carrier, a metal thin film is formed thereon, a semiconductor porcelain thin film is laminated thereon, and then a metal thin film is further laminated to form a unit laminate having a four-layer structure. It can be manufactured by stacking a plurality of laminates and applying pressure at a temperature at which the thermoplastic polymer of the carrier material melts and thermocompression bonding.

As the material of the thermoplastic polymer film, any thermoplastic resin can be used as long as it is chemically inert, has good dimensional stability and electrical insulation, and has low moisture permeability. Typical examples thereof include fluoro resins such as polytrifluorostyrene and trifluorochloroethylene resin (PCTFE).

The material of the metal thin film is gold,
In addition to noble metals such as silver, platinum, and palladium, nickel, copper, and other base metals can be used, but the two metal thin films facing each other with the semiconductor porcelain thin film interposed are not necessarily the same metal, and the semiconductor thin film formation process The best one may be selected from the viewpoint of harmony with the cost and cost. Further, as the material of the semiconductor porcelain thin film, any of known semiconductor porcelains can be used, and typical examples thereof include rare earth elements such as scandium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, and samarium. A barium titanate-based semiconductor ceramic is a typical example.

[0011]

The laminated capacitor according to the present invention is formed by laminating a thermoplastic polymer film, a semiconductor porcelain thin film, and a pair of metal thin films, and is formed at the interface between the metal thin film and the thermoplastic polymer film. The capacitance of the weir layer provides the capacitance. Therefore, a unit capacitor having a four-layer structure is used as a unit capacitor, and by integrating a plurality of these units, it is possible to increase the capacity of the multilayer capacitor.

[0012]

Example 1 Yttrium-doped barium titanate (BaYTiO ₃ ) was used as a semiconductor porcelain, platinum was used as a metal film material, and trifluorochloroethylene resin (PCTF) was used as a thermoplastic polymer film.
A capacitor having the structure shown in FIG. 1 was manufactured in the following manner using E).

First, barium carbonate, titanium oxide and yttrium oxide are blended so that the composition is Ba _1.03 Y _0.004 Ti _1.01 O _3, and the mixed powder is calcined at 900 ° C. to obtain a calcined powder. After molding into a disc, 2 at 1300 ° C
A porcelain disc made of BaYTiO ₃ was prepared by firing for a period of time.

Separately from this, a PCTFE film 1 having a length of 30 mm, a width of 20 mm and a thickness of 500 μm was prepared, and platinum (Pt) was used as a target by a known high frequency sputtering apparatus.
A platinum film 2 having a thickness of 0.5 μm was formed on the PCTFE film 1. Next, on the PCTFE film 1 on which the platinum film 2 is formed,
Targeting the porcelain disc in an argon atmosphere,
A BaYTiO ₃ thin film 3 having a thickness of 0.5 μm was formed at a temperature of 200 ° C. Further, on the obtained BaYTiO ₃ thin film 3, with the central portion between the platinum films 2 serving as the adjacent internal electrode lead-out portions of the surface thereof being masked, a film was made on the PCTFE film 1 with a high frequency sputtering device using platinum as a target. 0.5μ
A platinum film 4 having a thickness of m was formed to prepare a four-layer film of Pt / BaYTiO ₃ / Pt / PCTFE.

As shown in FIG. 2, three four-layer films having a thickness of about 500 μm thus produced were laminated on top of each other, and a thickness of 5 was formed on the four layers.
After laminating 00 μm PCTFE film 1 ', 2 in the mold
A pressure of about 10 kg / mm ² was applied with the temperature being raised to 00 ° C. and pressure bonding was performed to obtain a laminate having a length of 30 mm, a width of 20 mm and a thickness of 1.5 mm. This laminated body was cut into a size of 3 mm in length and 2 mm in width to obtain a capacitor chip 10 shown in FIG. Next, a silver paste was applied to both end faces of the opposing capacitor chips in which the internal electrode lead-out portions were alternately exposed and dried to form the external electrodes 5, and the chip-shaped capacitor element shown in FIG. 4 was produced. The capacitance of this capacitor element is frequency 1
When measured under the conditions of KHz and applied voltage of 1.0 Vrms, 8
It was 2.4 nF.

[0016]

Example 2 PCT having a length of 30 mm, a width of 20 mm and a thickness of 20 μm
On the FE film 1, in the same manner as in Example 1, a length of 2.8
A platinum film 2 having a thickness of 0 mm, a width of 20 mm and a thickness of 0.5 μm is formed, and a BaYTiO ₃ thin film having a thickness of 0.5 μm and a platinum film 4 having a thickness of 0.5 μm are formed on the platinum film 2 to form Pt / BaYTiO ₃ / Pt / PCTFE. A four-layer film was prepared.

Fifty sheets of the produced four-layer film having a thickness of about 20 μm were laminated in a mold, and a PCTFE film 1 ′ having a thickness of 20 μm was further laminated thereon, and then heated to about 200 ° C. for about 1 μm.
The laminate was pressed under a pressure of 0 kg / mm ² to obtain a laminate having a length of 30 mm, a width of 20 mm and a thickness of 1.5 mm. This was cut into a length of 3.00 mm and a width of 2.00 mm, and silver paste was applied to both end surfaces of the cut paste and dried to form the external electrodes 5, to produce a chip-shaped capacitor element. When the electrostatic capacity of this capacitor element was measured under the conditions of a frequency of 1 kHz and an applied voltage of 1.0 Vrms, it was 1.35 μF.

In the above embodiment, the metal thin film is laminated by masking the surface of the polymer film and the surface of the semiconductor porcelain thin film in order to form one internal electrode lead-out portion, but it is not always necessary to mask and the masking is not necessary. Alternatively, a metal thin film and a semiconductor porcelain thin film may be laminated.

[0019]

As is apparent from the above description, according to the present invention, a multilayer capacitor is provided with a thermoplastic polymer film, a metal thin film laminated on the thermoplastic polymer film, and a metal thin film on the metal thin film. Since it is configured as a unit laminated body having a four-layer structure composed of a semiconductor porcelain thin film laminated on the semiconductor porcelain thin film and a metal thin film laminated on the semiconductor porcelain thin film and forming a pair with the metal thin film, a high dielectric constant material is used. In addition, the structure of the part that forms the capacitance can be made as thin as a thin film capacitor or a weir layer capacitance type capacitor, and moreover, the unit area of four layer structure can be connected in parallel to increase the electrode area. Therefore, it is possible to obtain a small-sized, lightweight, large-capacity capacitor at low cost.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a unit laminated body of a laminated capacitor according to the present invention.

FIG. 2 is a cross-sectional view showing a state in which a plurality of unit laminated bodies of FIG. 1 are integrally laminated.

FIG. 3 is a cross-sectional view of a multilayer capacitor chip.

FIG. 4 is a cross-sectional view of a multilayer capacitor according to the present invention.

[Explanation of symbols]

 1-Thermoplastic polymer film 1'-Thermoplastic polymer film 2-Metal thin film 3-Semiconductor porcelain thin film 4-Metal thin film 5-External electrode 10 Capacitor chip

Claims (5)

[Claims] 1. A thermoplastic polymer film, a metal thin film laminated on the thermoplastic polymer film, a semiconductor porcelain thin film laminated on the metal thin film, and the metal laminated on the semiconductor porcelain thin film. A laminated capacitor having at least one unit laminated body having a four-layer structure composed of a thin film and a pair of metal thin films. 2. The multilayer capacitor according to claim 1, wherein the thermoplastic polymer film is made of a fluororesin. 3. The multilayer capacitor according to claim 1, wherein the semiconductor porcelain thin film is made of barium titanate-based semiconductor porcelain. 4. The multilayer capacitor according to claim 1, wherein the metal thin film is made of a noble metal or a base metal. 5. A thermoplastic thin film is formed on a carrier to form a metal thin film, and a semiconductor porcelain thin film is laminated on the metal thin film.
A multilayer capacitor, comprising: laminating metal thin films to form a unit laminate having a four-layer structure, and stacking a plurality of the unit laminates and thermocompression bonding.