JP2748580B2 - Capacitor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a capacitor used for various electronic devices.

2. Description of the Related Art Conventionally, when fine adjustment of the electric capacity in an electronic circuit is performed, a trimmer capacitor is generally used, and the adjustment is performed by manually or mechanically rotating an adjustment shaft.

In addition, there is also known a method of finely adjusting the electric capacity by removing the adjusting electrode formed by the thick film or thin film method thermally by using mechanical or optical energy.

However, in response to the recent trend of electronic circuits becoming smaller, lighter and more portable, the above trimmer capacitors are difficult to miniaturize, are expensive and require costly automation of work, and have a capacitance value due to mechanical vibration. Has a problem such as a change in On the other hand, in the method of finely adjusting the electric capacitance by thermally removing the adjusting electrode formed by the thick film or thin film method using mechanical or optical energy, the stability of the adjusted capacitance is insufficient. In addition, there is a problem that the cost is required for forming the electrodes, and the development of a small-sized, light-weight, low-cost, highly-reliable variable-capacitance capacitor and a simple method for adjusting the circuit constant has been desired.

As a means for solving the above problems, the present inventors have
A variable-capacitance type capacitor provided with a metal oxide thin film, a metal nitride thin film, a metal boride thin film alone or an electrode for adjustment made of a mixture thereof through a dielectric closely adhered to an electrode provided on a substrate. The adjustment method was developed.

Problem to be Solved by the Invention Above, the capacitor developed by the inventors of the present application was effective in the low-frequency region, but when used for high-frequency circuits, the metal oxide thin film, metal nitride thin film, The adjustment electrode made of a metal boride thin film alone or a mixture thereof has a drawback that the circuit resistance is deteriorated because the series resistance is increased.

Means for Solving the Problems As means for solving the above problems, the present invention provides a metal oxide thin film, a metal nitride thin film, and a metal boride via a dielectric closely adhered to an electrode provided on a substrate. It is configured such that a capacitance adjusting electrode made of a thin film alone or a mixture thereof and an electrode made of a metal electrode are provided in close contact with the dielectric.

Effect By using the capacitor according to the present invention, a capacitor for a variable capacitor having excellent high-frequency characteristics and easy to adjust the capacitance can be obtained.

Embodiment Hereinafter, as an embodiment of the present invention, a chip-shaped variable capacitance type capacitor will be described with reference to the drawings.

In FIG. 1, an electrode 2 formed on an insulating substrate 1
The dielectric material 3 is formed in close contact with the substrate, and the capacitance adjusting electrode 4 and the metal electrode 5 are further formed in close contact with the dielectric 3. The metal electrode 5 can also serve as the external terminal 6 as it is. However, in consideration of the manufacturing cost, the characteristics required for the terminal 6, and the like, the terminal 6 is usually used.
And the metal electrode 5 are preferably provided separately. That is,
Although a metal thin film is sufficient for the metal electrode 5 in terms of the characteristics of the capacitor, the extraction terminal 6 needs a certain thickness in consideration of soldering or the like.

As a material of the insulating substrate 1, a conventionally known substrate material can be used. For example, there are ceramic plates such as alumina, zirconia, and aluminum nitride, sapphire, quartz and other single crystal plates, glass plates, and thermoplastic or thermosetting resin molded plates. These can be used arbitrarily according to the application, but usually, inexpensive materials such as an alumina plate, a glass plate, and various resin plates are sufficient.

Various materials are known for the material of the electrode 2. For example, it can be formed by baking a metal material such as nickel, copper, gold, or silver in a foil shape or as a paste. In addition, it can be formed by a thin film forming method such as vapor deposition and sputtering.

Various materials are known as the material of the dielectric 3. However, in the case of a variable capacitance type capacitor, it is desirable that the capacitance change is as small as possible even in various environmental changes.
Usually, a material having a small relative dielectric constant is used. For example, there are a resin material such as a fluororesin and a polyolefin resin, a ceramic thin film such as alumina, titania, and barium oxide or a fired film. These can be laminated in close contact with the electrode 2 by fusion, baking, vapor deposition, or other methods.

A capacitance adjusting electrode 4 formed in close contact with the dielectric 3
It is preferable that the material has high conductivity as much as possible and can be removed by a simple operation.

Suitable materials include conductive thin film materials such as metal oxide thin films, metal nitride thin films, and metal boride thin films. These thin films are different from commonly used metal thin films in that they absorb visible light or near-infrared light, and as shown in FIG.
Can be effectively removed. Another advantage of using a metal oxide thin film, a metal nitride thin film, or a metal boride thin film as the capacitance adjusting electrode 4 is that, as shown in FIG. 3, the capacitor having the shape shown in FIG. In this state, the capacitance adjusting electrode 4 can be removed, that is, the capacitance can be adjusted by irradiating a laser beam without adversely affecting glass or the like without affecting the glass or the like. Since the capacitor after the adjustment is protected by the protective layer 8, an electronic circuit having excellent reliability can be obtained.

The thin film of the capacitance adjusting electrode 4 such as a metal oxide can be formed by a conventionally known thin film forming method such as vapor deposition or sputtering. However, the capacitance adjusting electrode 4 of the capacitor needs to be formed in a specific pattern. Therefore, a thin film formed by a so-called thermal decomposition method, in which an organic compound containing a metal such as a metal resinate is printed and thermally decomposed, is more preferable. It should be noted that a film formed by a normal thin film forming method can be naturally formed into a pattern by a technique such as etching or pattern masking.

In consideration of material cost, ease of pattern formation, and conductivity among the above electrode materials, oxidation produced by printing and baking an ink mainly composed of an organic compound containing ruthenium and other metals and a thickener. Ruthenium and its related compounds are particularly preferable as the material of the capacitance adjusting electrode 4.

Since the capacitance adjusting electrode 4 composed of the above-mentioned various thin films can be removed at high speed by light energy such as laser light, it is convenient for high-speed adjustment of an electronic circuit.

As the metal electrode 5, a metal that is usually used as an electrode material can be used. For example, gold, silver, copper, nickel,
Aluminum or an alloy of these metals is used. These metals can be formed on the dielectric 3 by a known method such as vapor deposition, sputtering, and plating.

It is desirable that the capacitance adjusting electrode 4 and the metal electrode 5 are electrically connected at both tangent lines as shown in FIG. As shown in FIG. 1, the capacitance adjusting electrode 4
Is arranged, the series resistance of the capacitor electrode can be minimized, and the deterioration of high frequency characteristics can be minimized. Further, as shown in FIG. 4, a large-area metal electrode 5 is provided on the dielectric 3, and a thin linear capacity adjustment electrode 4 is provided on one side of the metal electrode 5. A plurality of small-area metal electrodes 5a are provided in a row on the outside, and the metal electrodes 5 and 5a are electrically connected to each other by a capacitance adjusting electrode 4. When the capacitance is changed, the capacitance adjusting electrode 4 is irradiated with light energy. This can be done by removing, and the deterioration of the characteristics based on the capacitance adjusting electrode 4 can be practically ignored.

As shown in FIGS. 3 and 5, the capacitor has a protective layer 8 made of a thermoplastic or thermosetting resin, or various kinds of glass.
Protecting with, further increases the reliability.

In the above description, a chip-shaped capacitor and a method of adjusting the circuit constants of an electronic circuit incorporating the same have been described. However, as is clear from the above description, the capacitor of the present invention can be used as a circuit board or a hybrid integrated circuit. It is a matter of course that the circuit constants can be adjusted by the above-described method after directly forming them by a printing method or the like. Also, as shown in FIG. 5, it is natural that the lead wire 9 can be drawn out from the chip-shaped lead-out terminal 6 and used as a leaded component.

Effect of the Invention As described above, the capacitor according to the present invention is lightweight, small, has excellent reliability and characteristics in a high-frequency region, and its adjustment method is simple, which contributes to the improvement in reliability and cost reduction of various electronic circuits. Things.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the structure of a capacitor according to the present invention, FIG. 2 is a conceptual diagram of adjusting the capacitance of the capacitor according to the present invention using a laser beam or the like, and FIG. 3 is a book provided with an electrode protection layer. FIG. 4 is a cross-sectional view of the capacitor of the present invention, FIG. 4 is a plan view showing an example of a method of arranging metal electrodes and adjustment electrodes of the capacitor of the present invention, and FIG. . 1 ... Insulating substrate, 2 ... Electrode, 3 ... Dielectric, 4 ...
Electrode for capacitance adjustment, 5 ... Metal electrode, 6 ... Terminal for extraction, 7 ... Light beam, 8 ... Protective layer, 9 ... Lead wire.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Chiharu Hayashi 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Kanji Machida 1006 Kadoma Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. Inside

Claims (2)

(57) [Claims] 1. A capacitance adjusting electrode and a metal electrode each comprising a metal oxide thin film, a metal nitride thin film, a metal boride thin film alone or a mixture thereof via a dielectric closely attached to an electrode provided on a substrate. Is provided in close contact with the dielectric, and the capacitance adjusting electrode and the metal electrode are electrically connected. 2. The capacitor according to claim 1, further comprising a protective film for protecting the capacitance adjusting electrode and the metal electrode.