JP2817372B2 - Capacitor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable capacitance type capacitor used for various electronic devices.

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

In addition, there is also known a method of mechanically removing electrodes formed on both surfaces of a dielectric by a thick or thin film method, or a method of finely adjusting an electric capacity by removing the electrodes with light energy such as a laser.

However, in response to the recent trend toward smaller, lighter, and more portable electronic circuits, the above trimmer capacitors are difficult to miniaturize, are expensive and require high cost for automation, and have a large capacity due to mechanical vibration. There is a problem that the value changes. On the other hand, in the method of finely adjusting the electric capacitance by removing the adjustment electrode formed by the thick film or thin film method by mechanical or optical energy, it takes time for the adjustment, leading to an increase in cost, and after the adjustment, There are problems such as insufficient stability of capacitance and high cost for electrode formation. Therefore, development of a small, lightweight, low-cost and highly reliable variable capacitance capacitor and a simple circuit constant adjustment method is desired. It has been rare.

As a means for solving the above-mentioned problems, the present inventors have proposed a method of removing at least one of a metal oxide, a metal nitride, and a metal boride through a dielectric closely attached to a first electrode provided on a substrate. We have developed a variable capacitor that has an electrode for adjustment and a metal electrode electrically connected to it.

Problems to be Solved by the Invention The above-mentioned solution of the present inventors has been effective for use in high-frequency circuits, but the first solution provided on a substrate
Since the above-mentioned electrode is opposed to the above-mentioned metal electrode, it is difficult to reduce the minimum capacity to a specific value or less, and there is a disadvantage that the use range is limited.

Means for Solving the Problems As a means for solving the above-mentioned problems, the present invention provides a method for forming a second metal layer on a dielectric provided in close contact with a first metal electrode provided on a substrate. And an electrode for adjustment electrically connected to the second metal electrode are arranged so that the first metal electrode and the second metal electrode do not directly face each other, Further, the adjustment electrode is formed of a thin film made of at least one of a metal oxide, a metal nitride, and a metal boride.

In addition, the present invention provides a first metal electrode on one surface of a dielectric, and a second metal electrode on the other surface of the dielectric.
An electrode for adjustment electrically connected to the metal electrode of (1), wherein the second metal electrode is arranged so as not to directly face the first electrode, and Comprises a thin film composed of at least one of a metal oxide, a metal nitride, and a metal boride.

Further, the capacitor of the present invention is characterized in that a protective film for protecting the metal electrode and the adjustment electrode is provided.

Operation By using the capacitor of the present invention, a capacitor for variable capacitance having excellent high-frequency characteristics, easy adjustment of the capacitance, and a stable wide usable capacitance range can be obtained.

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

Example 1 In FIG. 1, the first substrate formed on the insulating substrate 1
A dielectric 3 is formed in close contact with the electrode 2, and a capacitance adjusting electrode 4 and a metal electrode 5 are formed in close contact therewith. In this case, as shown in FIG. 1, the first electrode 2 formed on the substrate 1 needs to be provided so as not to face the metal electrode 5. The metal electrode 5 can also serve as the terminal 6 for taking out to the outside as it is. However, in consideration of the manufacturing cost, characteristics required for the terminal 6, and the like, the terminal 6 and the metal electrode 5 are usually provided separately. Better. That is, a metal thin film is sufficient for the metal electrode 5 in terms of the characteristics of the capacitor, but the terminal 6 needs a certain thickness in consideration of soldering or the like.

 Hereinafter, the material of each part and an appropriate material will be described.

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 first electrode 2. For example, it can be formed by baking a metal material such as nickel, copper, gold, silver or the like in a foil form 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 also known as the dielectric material 3. However, in the case of a variable capacitance capacitor, it is desirable that the change in capacitance is as small as possible even in various environmental changes. For example, there are a resin material such as a fluororesin and a polyolefin-based 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 first electrode 2 by fusion, firing, vapor deposition or other methods.

Adjustment electrode 4 formed in close contact with dielectric material 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. Since these thin films are different from commonly used metal thin films and easily absorb visible light or near-infrared light, they can be effectively removed using a light beam 7 such as a laser beam or a halogen lamp as shown in FIG. it can. Another advantage of using a metal oxide thin film, a metal nitride thin film, or a metal boride thin film as an adjustment electrode as compared with a conventionally known metal thin film is that, as shown in FIG. To a protective layer 8 such as glass
In this condition, the electrodes can be removed, that is, the capacitance can be adjusted by irradiating a laser beam without causing an adverse effect on glass or the like, without causing any adverse effects on glass or the like. The reason why the electrode can be removed without affecting glass or the like is that the compound thin film can be removed with less energy than a metal thin film. Since the capacitor after the adjustment is protected by the protective layer, an electronic circuit with excellent reliability can be obtained. Further, in the capacitor of the present invention, since all of the electrodes for adjustment are removed, there is no portion facing the electrodes, so that the capacitance after adjustment can be made extremely small.

The above-mentioned compound thin film can be formed by a conventionally known thin film forming method such as vapor deposition or sputtering. However, since the adjusting electrode 4 of the variable capacitor needs to be formed in a specific pattern, it is difficult to use a metal resin oxide. A thin film formed by a so-called pyrolysis method, in which an organic compound containing a metal such as a salt is printed and thermally decomposed, is more desirable. It should be noted that a film formed by an ordinary thin film forming method can naturally be formed into a pattern by a technique such as etching or pattern masking.

In consideration of the material cost, ease of pattern formation, and conductivity, the electrode material is manufactured by printing and firing an ink mainly composed of an organic compound containing ruthenium and other metals and a thickener. Ruthenium and its related compounds are particularly preferred as materials for the adjustment electrode 4.

In addition, since the above-mentioned various thin film electrodes 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 film by a known method such as vapor deposition, sputtering, and plating.

The adjusting electrode 4 and the metal electrode 5 need to be electrically connected at both tangent lines as shown in FIG.

As shown in FIGS. 3 and 4, the variable capacitor is provided with a protective layer 8 made of a thermoplastic or thermosetting resin or various kinds of glass on the entire structure or above the substrate.
Protecting with, further increases the reliability.

In the above description, a chip-shaped variable capacitor and a method of adjusting the circuit constant of an electronic circuit incorporating the same have been described. As is clear from the above description, the variable capacitor of the present invention is mounted on a circuit board. Alternatively, it is a matter of course that the circuit constants can be adjusted by the above-described method after being directly formed in a hybrid integrated circuit by a printing method or the like. In addition, as shown in FIG.
Can be used as a leaded component by pulling out the lead wire 9 from the connector.

Example 2 Next, another embodiment of the example will be described.

In FIG. 5, a metal electrode 11 is provided on the upper surface of the dielectric block 10.
And an adjustment electrode 12 electrically connected thereto is provided, and an electrode 13 is provided on a surface of the dielectric block opposite to the adjustment electrode 12,
Form a capacitor. At this time, the metal electrode 11 and the electrode
13 is arranged so as not to directly oppose, and the capacitance is adjusted by removing the adjusting electrode 12 with light energy such as a laser.

The materials that can be used in this embodiment are the same as those described above, but the dielectric block can be manufactured using a green sheet used for a normal multilayer capacitor.

Embodiment 3 Further, when a large capacity is required, the internal electrodes 14 can be formed inside the block as shown in FIG. 6 in order to reduce the electrode spacing and maintain a predetermined shape. In this case, the internal electrodes are
Terminal directly from the end of 14 or through hole 15
Connection to 16 can be established. These techniques are well-known.

Effect of the Invention As described above, the capacitor of the present invention is lightweight, compact, has excellent reliability and excellent characteristics in a high frequency range, and has a wide capacity adjustment range, contributing to the improvement in reliability and cost reduction of various electronic circuits. .

[Brief description of the drawings]

FIG. 1 is a perspective view showing a capacitor according to a first embodiment of the present invention, FIG. 2 is a conceptual diagram in which the capacitance of the capacitor according to the present embodiment is adjusted using a laser beam or the like, and FIG. FIG. 4 is a perspective view of a capacitor provided in this embodiment, FIG. 4 is a cross-sectional view showing a leaded capacitor of one embodiment of the present invention, FIG. 5 is a cross-sectional view showing a capacitor of a second embodiment of the present invention, FIG. 6 is a sectional view showing a capacitor according to a third embodiment of the present invention. 1 ... Insulating substrate, 2 ... Electrode, 3 ... Dielectric, 4 ...
Adjustment electrode, 5: Metal electrode, 6: Terminal, 7: Light beam, 8: Protective layer, 9: Lead wire, 10: Dielectric block, 11: Metal electrode, 12: Adjustment Electrodes for use, 13 ... electrodes, 14 ... internal electrodes, 15 ... through holes, 16 ... terminals.

Continued on the front page (72) Inventor Chiharu Hayashi 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. ) Inventor, Kanji Machida 1006, Kazuma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-50-42369 (JP, A) JP-A-60-94716 (JP, A) Field surveyed (Int.Cl. ⁶ , DB name) H01G 4/00-4/40

Claims (3)

(57) [Claims] A first metal electrode provided on a first metal electrode provided on a substrate and a second metal electrode provided on a dielectric material provided in close contact with the first metal electrode provided on the substrate; A connected adjustment electrode, the first metal electrode and the second metal electrode are arranged so as not to directly face each other, and the adjustment electrode is a metal oxide, a metal nitride, A capacitor comprising a thin film made of at least one of metal borides. 2. A metal first electrode is provided on one surface of a dielectric, and is electrically connected to the second metal electrode and the second metal electrode on the other surface of the dielectric. The second metal electrode is arranged so as not to directly face the first electrode, and the adjustment electrode is formed of a metal oxide, a metal nitride, a metal borate, or the like. A capacitor comprising a thin film comprising at least one of the following: 3. The capacitor according to claim 1, further comprising a protective film for protecting the metal electrode and the adjustment electrode.