JPH0445510A - Capacitor - Google Patents

Abstract

PURPOSE:To reduce a dispersion of electrostatic capacitance for the positional deviation of electrode in any direction by setting up a particular positional relationship between T-shape electrodes having a particular length and width relationship and the electrode leadout part. CONSTITUTION:Assuming that the electrode leadout parts 1a and 2a of T-shape electrodes 1 and 2 are in the central parts of the electrodes, that 1b, 1c, 2b, and 2c are on the electrode side, and let the widths of both electrodes 1 and 2 be W, their lengths are represented with 2W and 1/2W, respectively. When no dislocation occurs in both electrodes 1 and 2, only overlapping area S0=2W<2> is generated between the central parts thereof. Although positional deviation Y of electrode occurs in the Y-direction, area S0 decreases by W Y, summing up area S1=S2=1/2W Y between side parts generates a decrement W Y, thus offsetting the deviation. Further, although when a deviation of X occurs in the X-direction, area S0 decreases by 2W X, area S3 and S4 totally decrease by 2W X, thus offsetting the deviation. Therefore, whether or not a deviation occurs in either electrode 1 or electrode 2, the capacitor can maintain a constant overlapping area and can suppress the dispersion of electrostatic capacitance to small.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a capacitor, and more specifically, to a high-precision capacitor electrode structure that reduces variations in capacitance due to positional displacement of electrodes.

(B) Prior art] The capacitance C of a capacitor is expressed as C=ε・S/d, where S is the overlapping area of the electrodes, d is the spacing between the electrodes, and ε is the dielectric constant between the electrodes. . Therefore, variations in area S due to positional deviation of the electrodes are immediately reflected in capacitance C.

Various factors can be considered as causes for the displacement of the electrodes of the capacitor. For example, in a multilayer capacitor made by laminating a large number of dielectric sheets with electrodes formed on them,
The mechanical accuracy of the laminating machine used during lamination is a major factor.

Conventionally, as a capacitor that suppresses variation in capacitance due to such positional deviation of electrodes to a small extent, JP-A-56-
The one described in Publication No. 71919 is known. This capacitor has an electrode 11. shaped as shown in FIG.
12 are placed together with a dielectric 13 in between.

The electrodes 11.12 are rectangular and have a main overlap area S
1 is brought to life. Electrode extraction portions 11d and 12d are connected to the electrodes 11 and 12, respectively. Electrode extraction part 11
d, 12d (7) width is the width W of electrode 11.12 (7)
A is set. Further, the lead-out portions of one electrode and the other electrode, ie, 12 and lid, and 11 and 12d, have overlapping areas Sb and Sc, respectively.

In this conventional capacitor, as shown in FIG. 6(b), even if the electrode position shifts in the electrode extraction direction X, the area S
The decrease by 1 is equal to the increase in the areas Sb, S, and the actual overlapping areas S1+S, +Se do not change after all. Although not shown, even if a positional shift occurs in the opposite direction in the
does not change. In any case, due to misalignment of the electrodes,
Variations in capacitance can be suppressed to a small level.

(c) Problems to be Solved by the Invention The laminating machines commonly used to manufacture the above-mentioned multilayer capacitors do not have uniform mechanical precision in all directions, and some have high mechanical precision in the electrode extraction direction, while others have high mechanical precision in the electrode extraction direction, and However, the mechanical precision of the electrode extraction direction is low.

As shown in Figure 6, etc., the above conventional capacitor is effective in the case of a laminated machine with low mechanical accuracy in the electrode extraction direction In the case of a laminating machine with a low S, as shown in FIG. 6(C), the decrease in the area S is no longer compensated for, and variations in capacitance cannot be suppressed.

The present invention has been made in view of the above, and aims to provide a capacitor that can suppress variations in capacitance even if the electrodes are misaligned in any direction.

(d) Means for solving the problems In order to solve the above problems, the capacitor of the present invention has T
It is a letter-shaped electrode, the length of the central part is twice the width,
The width of both sides is the width of the central part, and the length is 2 times this width.
Adjacent electrodes are placed symmetrically with each other through a dielectric material, and a major overlapping area is created between the center portions, and an electrode extraction portion is placed on one side of the center portion or side portion. The electrode extraction portions of adjacent electrodes that are arranged in series are located in opposite directions.

(E) Function The function of this invention will be explained with reference to FIG. FIG. 5 is a diagram illustrating the overlapping area of T-shaped electrodes 1.2, where 1a and 2a are electrode center parts -11b, IC12b, 2
C is the side part of the electrode, W represents the width of the center part and the side part, and the lengths of the center part and the side part are 2W and '/2W, respectively.

FIG. 5(a) shows the case where there is no positional deviation in the electrode 1.2, and the overlapping area S, (=2
Since the electrodes 1.2 are located symmetrically, if there is no misalignment, the sides 1b, IC and 2
No overlapping area occurs between 0.2b.

FIG. 5(b) shows a state in which the ΔY electrode 1.2 is displaced in the X direction. The area S0 has decreased by WΔY. However, overlapping areas St and St occur between the side portions 1b and 20, and between the IC and 2b, respectively. This area S1
, S2 are both 'AWΔY, and the sum is WΔY. Therefore, the increase and decrease in area are equal, and the actual overlapping area So+S++SZ is 2W'', as shown in Figure 5 (
It is no different from case a).

FIG. 5(C) shows a case where the ΔX electrode 1.2 is displaced in the X direction. Area 30 decreases by 2WΔX.

However, the side part 1b and the center part 2a, and the side part 2b and the center part l
Overlapping areas S1 and S4 are generated between a, respectively. These areas S3 and S4 are both 2WΔX when summed by WΔX
becomes. Therefore, the increase and decrease in area are equal, and the substantial overlapping area is S o + S 3 + S a
is 2Wz, which is also the same as the case in FIG. 5(a).

Therefore, even if the positional misalignment of the electrodes 1.2 occurs in either the X direction or the X direction, the overlapping area between the electrodes 1.2 can be kept constant, and variations in capacitance can be suppressed to a small level.

(F) Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 2 is a longitudinal sectional view of the example capacitor, and FIG. 3 is a diagram illustrating the stacked state of the same capacitor. This capacitor consists of alternating layers of ceramic sheets 3a and 3b each having an electrode 1.2 formed thereon (see FIG. 3). The electrode 1.2 is formed by screen printing a noble metal paste made of platinum, palladium or an alloy thereof. Electrode extraction parts 1d and 2d each having a width W are connected to the side parts 1b and 2b of the electrode 1.2, respectively.
d and 2d are taken out in opposite directions.

The ceramic sheets 3a and 3b are laminated using a laminating machine (not shown), heated and pressed, and then fired at a temperature of, for example, about 1300°C. The ceramic sheets 3a and 3b are integrated to form a dielectric ceramic 3 (see FIG. 2). On the side surface of the dielectric ceramic 3, lead-out electrodes 4.5 are formed which are electrically connected to the electrode lead-out portions 1d, . . . , 1d, and 2d, .

FIG. 1 shows the overlapping state of the electrodes 1.2. la
, 2a are the electrode center portion 1b and the IC 22b.

2C shows the side part of the electrode. In this case, a laminating machine with high mechanical precision is used in the electrode extraction direction X, and a deviation of ΔY occurs in the direction Y perpendicular to the electrode extraction direction X. This corresponds to the case in FIG. 5(b) above,
The decrease WΔY in the overlapping area 80 between the central parts 1a and 2a is the overlapping area S between the side parts 1b and 2c, the side parts 1c and 2b,
.

If the laminating machine has high mechanical precision in the X direction, ΔY can be reduced to almost zero. In that case, the positional deviation of electrodes 1.2 may occur in the X direction, but even in this case, the actual overlapping area between electrodes 1.2 does not change, as explained in FIG. 5(C). However, variations in capacitance can still be suppressed.

FIG. 4 is a diagram illustrating a modification of this embodiment. In this case, electrode central portions 1a and 2a are provided with electrode extraction portions 1e and 2e each having a width W, respectively. In addition, in the case of this figure, the direction in which the laminating machine has high mechanical precision coincides with the X direction, and a positional deviation ΔX occurs in the electrode extraction direction X-. Of course, this positional shift ΔX does not cause any change in the substantial overlapping area between the electrodes 1 and 2, and the capacitance does not vary.

Note that the dielectric material is not limited to ceramics, but may be appropriately designed such as mica or glass.

(G) As described in detail, the capacitor of the present invention is a T-shaped electrode, the length of the central portion is twice the width, and the width of both side portions is the width of the central portion. And its length is 1/2 of this width
Adjacent electrodes are placed symmetrically with each other through a dielectric material, with a major overlapping area created between the central parts, and an electrode extraction part is connected to one side of the central part or the side part. Since the electrode extraction parts of adjacent electrodes are located in opposite directions, even if the electrodes are misaligned in any direction, the actual overlapping area between the electrodes can be prevented from changing, and the electrostatic This has the advantage that variations in capacity can be kept small.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the overlapping state of electrodes of a capacitor according to an embodiment of the present invention, FIG. 2 is a longitudinal cross-sectional view of the capacitor, and FIG. 3 is a diagram illustrating the stacked state of the capacitor. Figure 4 is a diagram explaining a modification of the same capacitor, Figure 5 (al), Figure 5 (b) and Figure 5 (C) are diagrams explaining a detailed explanation of the invention, and Figure 6 is a diagram explaining a modification of the same capacitor. FIG. 6(a), FIG. 6(b), and FIG. 6(C) are diagrams each explaining a conventional capacitor. 1 and 2: Electrode, 1a and 2a: Center part of electrode, 1b-1
c, 2b, 2c: electrode side part, 1d, 2d: electrode extraction part. 3: Dielectric ceramic. Patent Applicant: ROHM Co., Ltd. Agent, Patent Attorney: Shigeru Nakamura Shin Figure (a) Ichimu 4- ΔX

Claims (1)

[Claims] (1) A T-shaped electrode, the length of the central part is twice the width, the width of both sides is the width of the central part, and the length is half of this width. Adjacent electrodes are placed symmetrically with each other through a dielectric material, a major overlapping area is created between the central parts, and an electrode extraction part is connected to one side of the central part or the side part. A capacitor in which the electrode extraction parts of matching electrodes are located in opposite directions.