JPH07183163A - Trimming capacitor - Google Patents

Abstract

PURPOSE:To provide a trimming capacitor in which trimming electrodes and an internal electrode are formed on one surface side and has such a structure that can prevent the occurrence of warps at the time of sintering. CONSTITUTION:A trimming capacitor is provided with trimming electrodes 3 formed on the surface of a dielectric 1 and an internal electrode 2 formed in the shape of a layer in the dielectric 1 near the surface of the dielectric 1. The capacitor is also provided built-in dummy electrodes 5 for preventing the occurrence of warps at the time of sintering. The electrodes 5 are provided at a depth from 0.05mm to 40% of the thickness of a chip from the surface of the dielectric 1 opposite to the surface of the dielectric 1 on which the electrode 3 is formed. Since the capacitor is provided with the built-in dummy electrodes 5, the electrodes 5 do not touch a conductor pattern on a substrate when the capacitor is mounted on the substrate. When multiple dummy electrodes 5 are provided in the direction of lamination and layers of the dielectric 1 are put between each dummy electrode 5, the occurrence of voids can be prevented in the capacitor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is constructed as a chip-shaped sintered body by a laminated structure of a ceramic dielectric and a conductor, and in an oscillation circuit or the like, the capacitance can be varied with high accuracy by trimming electrodes. The present invention relates to a trimming capacitor used when it needs to be set.

[0002]

2. Description of the Related Art FIG. 3A is a vertical cross-sectional view showing an example of a conventional trimming capacitor, and a dielectric material 1 such as barium titanate or titanium oxide is formed by a screen printing method, a sheet method, or a combination of these methods. Are laminated and formed, internal electrodes 2, 2 made of platinum, palladium, silver or an alloy thereof are formed in the vicinity of one surface, and trimming electrodes 3 made of the same conductive material are formed in an island shape on the surface, that is, the other. Is formed without being connected to the electric conductor, and after cutting and sintering, external electrodes (terminal electrodes) 4 and 4 respectively connected to the internal electrodes 2 and 2 are formed on the side surfaces by baking or plating. This trimming capacitor can be represented by an equivalent circuit in which the respective capacitance components between both internal electrodes 2 and 2 and trimming electrode 3 are connected in series, so that a capacitance larger than that required in advance can be obtained. After manufacturing, for example, forming an oscillation circuit, the trimming electrode 3 is trimmed with a laser beam or the like to obtain desired circuit characteristics.

The example of FIG. 3B shows an internal electrode 2 near the surface.
Is formed in an island shape and the trimming electrodes 3 and 3 on the surface are connected to the external electrodes 4 and 4, respectively, and one or both of the trimming electrodes 3 and 3 is trimmed to adjust the capacitance.

[0004]

In such a trimming capacitor, a certain thickness or more is required to secure desired mechanical rigidity and handleability, and the thickness is, for example, 0.6 mm or 0.8 mm. , 1.1 mm or the like. On the other hand, it is difficult to obtain the electrode area when downsized,
In order to obtain the desired capacitance, the thickness of the dielectric layer between the internal electrode 2 and the trimming electrode 3 must be reduced, and as a result, as shown in FIGS. 3 (A) and 3 (B), The internal electrode 2 and the trimming electrode 3, that is, the conductor layer is concentrated on one surface. In this way, the electrodes 2, 3 are
Is concentrated, as shown in FIG. 4 (A) or (B),
A warp r occurs in the trimming capacitor due to a difference in sintering or a contraction rate between the dielectric 1 and the electrodes 2 and 3 due to sintering.
For example, in the case where the thickness of the chip excluding the external electrodes 4 is 0.6 mm and the width and width are 3.2 mm × 2.5 mm, the electrodes 2,
When palladium is used as the material of 3 and a titanium oxide-based material is used as the material of the dielectric 1, the thickness of the trimming electrode 3 and the warpage r (see FIG. 4) when sintered at 1350 ° C.
As for the relationship with, the result is obtained as shown in FIG. Figure 5
As is clear from the above, the greater the thickness of the dielectric 1, that is, the thickness of the capacitor, the greater the warp. Therefore, in order to reduce such a warp, it is sufficient to thin the trimming electrode 3 and the like. However, if the trimming electrode 3 and the internal electrode 2 are made too thin, the Q at a high frequency is lowered, so that the trimming is performed to some extent. The thickness of the electrode 3 must be ensured. Therefore, in reality, a warp is inevitable in the conventional structure, and if the thickness of the trimming electrode 3 is about 16 μm, a warp of about several tens μm occurs. When such warpage occurs, there arises a problem that manufacturing, transportation and handling in an inspection line cannot be performed favorably, or soldering to a substrate cannot be favorably performed.

In view of the above-mentioned problems, it is an object of the present invention to provide a trimming capacitor having a structure in which a trimming electrode and an internal electrode are concentrated on one surface side and which can prevent warpage due to sintering from occurring. To do.

[0006]

In order to achieve the above object, the present invention provides a trimming electrode formed on the surface of a dielectric and the surface of the dielectric so as to face the trimming electrode through the dielectric. In a trimming capacitor made of a sintered body having a layered internal electrode formed in the vicinity thereof, a dielectric layer having a depth of 0.05 mm from the surface of the dielectric material opposite to the trimming electrode formation surface is formed. 40%
It is characterized in that a dummy electrode layer having a small influence on the electrical characteristics is provided up to the depth of. In the present invention, it is more preferable that the dummy electrodes are provided in a plurality of layers in the stacking direction and a dielectric layer is provided between the layers.

[0007]

According to the present invention, since the dummy electrode provided inside is formed in the region opposite to the trimming electrode, the trimming electrode and the internal electrode facing the trimming electrode shrink relatively to the dielectric. When acting in the (stretching) direction, the dummy electrode also acts in a direction of contracting (stretching) the portion of the dielectric material on the side opposite to the trimming electrode, so that the warpage of the main dielectric material is suppressed. In order to exert such an effect of suppressing the warp, the dummy electrode requires a certain thickness, but if the dummy electrodes are provided in multiple layers to ensure the total thickness, the thickness of each dummy electrode can be reduced. It can be made thin, and the generation of internal voids that tends to occur when the built-in electrode is made thick is avoided.

[0008]

1A is a vertical sectional view showing an embodiment of a trimming capacitor according to the present invention, which is of the type shown in FIG. 3B, that is, the trimming electrode 3 is connected to an external electrode 4 to form a rectangular parallelepiped shape. It is an example in which the present invention is applied to the formed one. Reference numeral 5 denotes a dummy electrode added according to the present invention, and as the material thereof, platinum, palladium, silver or an alloy thereof is used, like the internal electrode 2 and the trimming electrode 3. The dielectric 1 is also made of barium titanate, titanium oxide or the like as described above, but in the present invention,
Needless to say, the materials of the dielectric 1 and the electrodes 2, 3, 5 are not limited to these.

As described above, when the dummy electrode 5 is provided, the dummy electrode 5 acts on the dielectric 1 in the same manner as the trimming electrode 3 when contracting due to sintering, and prevents the dielectric 1 from warping. be able to. That is, if the electrodes 2, 3 and 5 have a contraction rate larger (smaller) than the dielectric body 1 at the time of sintering, the dummy electrode 5 is the same as the trimming electrode 3 or the internal electrode 2 in the same manner as the trimming electrode 3 or the internal electrode 2. In a region approximately opposite to 2, it has an effect of further contracting (preventing contraction) of the dielectric 1 in the peripheral portion of the dummy electrode 5, and as a result, warpage of the dielectric 1 is prevented. A specific example will be described. As the dielectric 1 and the electrodes 2, 3 and 5, the same material as that described in the conventional example is used, and the thickness t of the chip excluding the external electrode 4 is 0.6 mm. In the case where the vertical and horizontal dimensions are 3.2 mm × 2.5 mm, the thickness of the trimming electrode 3 is 9.0 μm, the thickness of the internal electrode 2 is 2.0 μm, and the thickness of the dummy electrode 5 is 2.0 μm, The warp could be suppressed to 10.0 μm or less. Further, according to this embodiment, since the dummy electrode 5 is connected in parallel to the trimming electrode 3, the resistance can be reduced and the Q can be improved.

In the present invention, the chip thickness t is 0.5 mm to 1.3 mm, and the vertical and horizontal dimensions of the chip are 3.2.
mm × 2.5 mm to 4.5 mm × 3.2 mm, the distance b between the internal electrode 2 and the trimming electrode 3 is 4.0 μm to 10.0 μ
m (ratio of the interval and the thickness t, b / t = 0.3% to 2.
0%), and the thickness of the trimming electrode 3 is 5.0 μm to 9.0.
μm, and the thickness of the internal electrode 2 is set to 1.0 μm to 3.0 μm, the dummy electrode 5 has a depth s of 0.05 mm or more from the surface opposite to the surface on which the trimming electrode 3 is formed, 0.4 times or less of the thickness t of the dielectric 1 (more preferably 0.07 mm or more, 0.35 of the thickness t
It is formed within the range of less than twice. The thickness of the dummy electrode 5 is set in the range of 1.0 μm to 3.0 μm (more preferably 1.5 μm to 2.5 μm).

The reason why the dummy electrode 5 is provided inside the dielectric 1 is that when this trimming capacitor is mounted on the conductor pattern of the substrate (not shown), the conductor portion other than the external electrode 4 contacts the conductor pattern. This is to eliminate the possibility of The reason why the depth of the dummy electrode 5 is set to 50 μm or more is that the surface of the electrode is insulated with a ceramic (dielectric) so that even if a crack or crack is generated on the surface, the dummy electrode 5 and other circuit patterns are not formed. This is for the purpose of preventing a short circuit with the dummy electrode 5 and the reason why the depth of the dummy electrode 5 is set to 0.4 times the thickness t of the dielectric 1 is that the influence on the electrical characteristics becomes greater. Is large, and the warp prevention effect cannot be expected so much.

In order to prevent the dummy electrode 5 from affecting the electrical characteristics of the capacitor as much as possible, the distance a between the dummy electrode 5 and the internal electrode 2 and the internal electrode 2 and the trimming electrode 3 are set. Ratio a / b with interval b is 50-80
And In this embodiment, since the pattern of the dummy electrode 5 is the same as the pattern of the trimming electrode 3,
The advantage is that the same printed pattern as the trimming electrode 3 can be used.

FIG. 1B shows another embodiment of the present invention.
In this embodiment, the dummy electrodes 5 are formed in two layers. If the dummy electrodes 5 are formed in two layers or more and the dummy electrodes 5 are formed as a dielectric layer, the dummy electrodes 5 are formed. The thickness of the layer can be reduced, and when the dummy electrode 5 is made of a material having a different contraction rate other than the dielectric as the internal electrode, a problem occurs when the different layers are thickened, that is, the dummy electrode 5 and the dielectric. It is possible to eliminate the generation of voids at the joint with 1.

FIG. 2A shows another embodiment of the present invention,
The dummy electrode 5 is formed as an island-shaped electrode that is not connected to the external electrode 4. In this embodiment, the trimming electrode 3 connected to the external electrode 4 and the dummy electrode 5 do not directly face each other. There is an advantage that the influence on the electric characteristics due to the provision is reduced.

In the above embodiment, the trimming electrode 3
The example in which the external electrode 4 is connected to the
As shown in (B), the trimming electrode 3 may be formed in an island shape. In the case of the present embodiment, since the dummy electrode 5 is connected to the external electrode 4 and the dummy electrode 5 does not directly face the trimming electrode 3, the influence of the provision of the dummy electrode 5 on the electric characteristics of the capacitor becomes smaller. .

The present invention can also be applied to the case where a plurality of capacitors are formed in the plane direction of the dielectric 1 (perpendicular to the plane of the drawing).

[0017]

According to the first aspect of the present invention, since the dummy electrode is provided within a certain depth range from the surface on the opposite side of the trimming electrode, the dielectric material at the time of sintering by the trimming electrode and the internal electrode closely facing the trimming electrode. It is possible to prevent the warpage due to the difference in shrinkage rate between and. Therefore, it is possible to provide a trimming capacitor that can be smoothly transported and handled in the manufacturing and inspection lines, and can be attached to a substrate by soldering, and the yield is improved. Further, since the dummy electrode is formed inside, there is no possibility that the substrate on which the capacitor is mounted will come into contact with the dummy electrode.

According to the second aspect, since the plurality of layers of dummy electrodes are provided inside, each dummy electrode can be thinly formed, and it is possible to prevent the generation of the void between the dummy electrode and the dielectric.

[Brief description of drawings]

1A and 1B are vertical cross-sectional views showing an embodiment of a trimming capacitor according to the present invention.

2A and 2B are vertical sectional views showing another embodiment of a trimming capacitor according to the present invention.

3A and 3B are vertical cross-sectional views showing a conventional trimming capacitor.

4 (A) and 4 (B) are vertical cross-sectional views showing warpage due to sintering in a conventional trimming capacitor.

FIG. 5 is a diagram showing a correlation between a trimming electrode and a warp in a conventional trimming capacitor.

[Explanation of symbols]

 1 Dielectric 2 Internal electrode 3 Trimming electrode 4 External electrode 5 Dummy electrode

Claims (2)

[Claims] 1. A laminate comprising a trimming electrode formed on a surface of a dielectric, and an internal electrode formed in a layer inside the dielectric near the surface so as to face the trimming electrode via the dielectric. In a trimming capacitor made of a sintered body having a structure, the electrical characteristics of the trimming capacitor are increased to a depth of 0.05 mm from the surface opposite to the trimming electrode formation surface of the dielectric or to a depth of 40% of the chip thickness dimension. A trimming capacitor having a dummy electrode layer having a small influence. 2. A trimming capacitor according to claim 1, wherein a plurality of said dummy electrodes are provided in a stacking direction and a dielectric layer is provided between each dummy electrode.