JPH0810178Y2 - Multilayer capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a multilayer capacitor having a structure capable of realizing a desired capacitance, and more particularly to a capacitor provided with a correction electrode for correcting the capacitance.

[Conventional technology]

As is well known, in a multilayer capacitor, a plurality of internal electrodes are arranged so as to overlap with each other via a dielectric ceramic layer. In the case of realizing a desired capacitance in a multilayer capacitor, it is usual to change the number of dielectric ceramic layers sandwiched between internal electrodes for taking out the capacitance. The number of layers n is generally calculated by n = (113 × C · t) / (ε · S). C is the capacitance value to be realized (unit is pF), t is the thickness (mm) of the dielectric ceramic layer,
ε is the relative permittivity, S is the effective overlap area between internal electrodes (m
m ² ) is shown.

However, when n is not an integer as a result of calculation by the above equation in order to realize a certain capacitance value C, there is a problem when n is 8.3, for example.

When n is not an integer, conventionally, the desired capacitance value C is realized by adopting the following method.

The first method is to manufacture a multilayer capacitor that has been rounded and formed with rounded integer layers. In this case, from the many manufactured multilayer capacitors, those which match the capacitance value C were selected. However, as a matter of course, the center of the distribution of the capacitance values of the obtained multilayer capacitor deviates considerably from the capacitance value C. Therefore, there is a problem that the yield rate is extremely low.

Secondly, as shown in FIG. 2, among the internal electrodes 2 to 6 arranged in the sintered body 1, the thickness of the dielectric ceramic layer between the internal electrodes 5 and 6 is increased. The method has been adopted. For example, in the case of n = 8.3, the internal electrodes 2 to 5 (some internal electrodes are omitted in FIG. 2) corresponding to the number of layers of n = 8.0 are laminated to form an internal layer. By interposing a dielectric ceramic layer 7 which is three times the thickness of the dielectric ceramic layer between other internal electrodes between the electrode 5 and the internal electrode 6, the capacitance value C of the multilayer capacitor of n = 8.3 can be approximated. Is.

However, even if the dielectric ceramic layer 7 and the internal electrode 6 as described above are used, the capacitance value C in the case of n = 8.3 cannot be directly realized, and the non-defective rate is still insufficient. Besides, the dielectric ceramic layer 7 having a different thickness from other dielectric ceramic layers must be arranged,
Therefore, at the time of manufacturing, a step of inserting a ceramic green sheet different from other ceramic green sheets (having no electrode pattern formed) must be performed. Therefore, there is also a problem that the manufacturing process becomes complicated.

Third, the auxiliary electrode 16 shown in FIGS. 3 (a) and 3 (b).
A structure provided with is known. Here, inside the ceramic sintered body 11, the internal electrodes 12 to 15 necessary to realize the capacitance value when n = 8 are arranged. And internal electrodes
Auxiliary electrode 16 overlapping 15 with a dielectric ceramic layer
Is provided. The width of the auxiliary electrode 16 is different from that of the internal electrode 12
.About.15, but its length is shorter than the other internal electrodes as shown in the schematic view seen from below in FIG. 3 (b), whereby the overlapping area with the internal electrodes 15 is increased. ,
It is configured to be 0.3 times the overlapping area of the internal electrodes.

Therefore, with the multilayer capacitor using the auxiliary electrode 16, it is possible to obtain a multilayer capacitor having a capacitance equivalent to the capacitance value C when n = 8.3.

[Technical problem to be solved by the invention] However, in the multilayer capacitor using the auxiliary electrode 16 of FIG. 3, if the formation position of the auxiliary electrode 16 in the width direction W is slightly deviated, the capacitance value changes considerably. Therefore, there is a drawback that a desired capacitance value cannot be obtained with high accuracy and stability.

Further, the shape of the multilayer capacitor is usually quite small, and the distance between both end faces of the sintered body 11 of the multilayer capacitor 10 is also considerably short. Therefore, in such a minute component, it is extremely difficult to exactly overlap the auxiliary electrode 16 with the internal electrode 15 by the distance of 0.3x shown in FIG. 3, and as shown in FIG. The overlapping area had to be varied in the L direction as well.

Therefore, even if the capacitor is manufactured for the purpose of the capacitance value in the case of n = 8.3, the capacitance value of the obtained multilayer capacitor has to be dispersed in a considerable range.

Therefore, an object of the present invention is to provide a multilayer capacitor having a structure capable of achieving a desired capacitance value with higher accuracy.

[Means for solving technical problems]

In the multilayer capacitor of the present invention, a plurality of internal electrodes are arranged in a sintered body made of a dielectric ceramic so as to overlap each other via a dielectric ceramic layer, and the plurality of internal electrodes are made of a sintered body. It is drawn out to either one of the two opposite end faces. Then, among the plurality of internal electrodes, one internal electrode located in the outermost layer in the thickness direction is arranged outside the plurality of internal electrodes so as to overlap with each other via the dielectric ceramic layer, Further, a correction electrode for capacitance correction is provided so that the overlapping area thereof is different from the overlapping area of the internal electrodes. The correction electrode is drawn out to one end surface of the sintered body, the width thereof is narrower than the width of the internal electrode, and the correction electrode is formed so as to be located within the width of the internal electrode. There is.

Note that the expression "width" of the correction electrode and the internal electrode means that the direction in which the internal electrode extends from the end surface of the sintered body to which the external electrode is applied is the length direction, and the direction orthogonal to the length direction is It means the distance in the width direction when the width direction is used.

[Action]

In the present invention, since the width of the correction electrode is formed so as to be narrower than the width of the internal electrode and positioned within the width of the internal electrode, even if the formation position of the correction electrode is slightly deviated in the width direction, It is unlikely that the overlapping area with respect to the internal electrodes that overlap with each other via the dielectric ceramic layer changes. Therefore, since the correction capacitance by the correction electrode can be realized with high precision, a multilayer capacitor having a desired capacitance value can be obtained stably and with high precision.

[Explanation of Example]

FIG. 4 is a sectional view of a multilayer capacitor according to an embodiment of the present invention. In the multilayer capacitor 20, a plurality of internal electrodes 22 to 25 are arranged in a sintered body 21 made of a dielectric ceramic so as to overlap with each other via a dielectric ceramic layer.
The plurality of internal electrodes 22 to 25 are alternately drawn out to the opposed end faces of the sintered body 21 in the thickness direction of the sintered body 21.

External electrodes 26 and 27 are formed on opposite end surfaces of the sintered body 21. Therefore, each capacitance taken out by the dielectric ceramic layer between the plurality of internal electrodes 22 to 25 is
It is connected in parallel between 6 and 27.

Further, a correction electrode 29 is arranged below the lowermost internal electrode 25 with a dielectric ceramic layer 28 interposed therebetween so as to overlap each other. The thickness of the dielectric ceramic layer 28 is
It is equal to the thickness of the dielectric ceramic layer between ~ 25. Therefore, it is not necessary to prepare a dummy ceramic green sheet used when forming the dielectric ceramic layer 7 in the conventional example of FIG.

 The feature of this embodiment is the shape of the correction electrode 29.

As is apparent from FIG. 4, the correction electrode 29 is an external electrode.
It is configured to have the same length as the other internal electrodes 22 and 23 connected to 26.

However, as is clear from FIG. 1 which is a schematic view of the sintered body 21 seen from below the correction electrode 29, the width of the correction electrode 29 is considerably narrower than that of the internal electrode 25. Therefore, the area of the region where the correction electrode 29 and the internal electrode 25 overlap with each other through the dielectric ceramic layer 28 (FIG. 4) is considerably smaller than the overlapping area of the internal electrodes 22 to 25. .

In the present embodiment, the width of the correction electrode 29 is narrowed so as to adjust the overlapping area of the correction electrode 29 and the internal electrode 25, that is, the overlapping area to obtain a desired capacitance value. . For example, when trying to realize the capacitance value C when n = 8.3 described above, the width of the correction electrode 29 is set to 3/10 of the width of the other internal electrodes 22 to 25,
By arranging 29, a capacity of only n = 0.3 minutes can be realized.

Moreover, since the width of the correction electrode 29 is narrowed, even if the correction electrode 29 is in the W direction in FIG.
Even if they are formed with a slight deviation, the overlapping area does not change as long as they fit within the width of the internal electrode 25. Further, even if it is formed with a slight deviation in the L direction, the variation range of the capacitance is much smaller than in the case of the conventional example of FIG.

Therefore, the capacitance correction in the multilayer capacitor can be performed with high accuracy by using the correction electrode 29 having a narrow width.

When the non-defective product ratio in the case of n = 5.3 was tested, the non-defective product in the case of the above-mentioned rounding method, the case of forming the wide dielectric ceramic layer of FIG. 2 and the case of using the correction electrode of the present invention The rates were as follows:

FIG. 5 is a schematic diagram for explaining another embodiment of the present invention and is a diagram corresponding to FIG. In the example shown in FIG. 1, only the width of the correction electrode 29 is narrower than that of the internal electrode 25. However, in the embodiment shown in FIG. 5, the correction electrode 39 is different not only in width but also in length from the internal electrode 25. Has been done. That is,
The overlapping area of the correction electrode with the internal electrode may be adjusted not only by changing the width of the correction electrode but also by changing the length thereof.

FIG. 6 (a) is a sectional view for explaining the third embodiment of the present invention. The third embodiment is applied to a multilayer capacitor having a structure in which a plurality of capacitors are connected in series. In the multilayer capacitor 40, inside the sintered body 41, internal electrodes 42, 43, 44, 45, 46, 47 extending from both end surfaces of the sintered body 41 are formed.
Are arranged in a butting manner at a predetermined distance in the center of the sintered body 41. Then, the internal electrodes 48, 49 are formed in the central portion of the sintered body 41 so as to partially overlap the internal electrodes 42-47.
Is arranged.

The internal electrodes 48 and 49 partially overlap the adjacent internal electrodes 42 to 47 to thereby form a plurality of capacitors with the external electrodes 50 and 5.
It is provided to provide a structure in which one is connected in series.

Also in the multilayer capacitor 40, a desired capacitance value can be realized by disposing the correction electrode 52 overlapping the internal electrodes 42 and 43. That is, when arranging the correction electrode 52 that partially overlaps the internal electrodes 42, 43, as shown in FIG.
The correction capacitance can be added by configuring the pattern with a width narrower than 3. Also in this case, since the width of the correction electrode 52 is narrower than the width of the internal electrodes 42, 43, it can be seen that the correction capacitance can be added with high precision as in the embodiment of FIG.

It is needless to say that also in the multilayer capacitor 40, the correction capacitance can be adjusted by taking into consideration that the correction electrode 52 has a different length from the other internal electrodes 48 or 49 in addition to the width.

In the first to third embodiments, the correction electrodes 29, 39, 52 are arranged outside the portion where the other internal electrodes are provided in the sintered body 41, but the correction electrodes are formed at the internal electrodes. May be between the overlapping portions of. That is, it is not always necessary to arrange the correction electrode on the outermost layer.

[Effect of device]

As described above, according to the present invention, the width of the correction electrode is narrower than the width of the internal electrode and is formed so as to be located within the width of the internal electrode. A multilayer capacitor having a desired capacitance value can be obtained with high accuracy and stability regardless of accuracy.

[Brief description of drawings]

FIG. 1 is a schematic bottom view for explaining the relationship between the shape of a correction electrode and an internal electrode in one embodiment of the present invention, and FIG. 2 is a cross-sectional view for explaining an example of a conventional multilayer capacitor,
FIG. 3 (a) is a cross-sectional view for explaining another example of the conventional multilayer capacitor, FIG. 3 (b) is a schematic bottom view for explaining the shape of the correction electrode in the conventional example, and FIG. Is a cross-sectional view of the multilayer capacitor of one embodiment of the present invention, FIG. 5 is a schematic bottom view for explaining the shape of the correction electrode and the internal electrode in the second embodiment of the present invention, and FIG. 6A and 6B are cross-sectional views and FIG. 6B is a schematic plan view for explaining the shapes of a correction electrode and an internal electrode. is there. In the figure, 20 is a multilayer capacitor, 21 is a sintered body, and 22-25.
Is an internal electrode, and 29 is a correction electrode.

Claims (1)

[Scope of utility model registration request] 1. A sintered body made of a dielectric ceramic, and one of the two opposing end faces of the sintered body, which are arranged in the sintered body so as to overlap each other with a dielectric ceramic layer interposed therebetween. From the plurality of internal electrodes so as to overlap with one internal electrode located in the outermost layer in the thickness direction among the plurality of internal electrodes through the dielectric ceramic layer. And a correction electrode for capacitance correction that is arranged outside and the overlapping area thereof is different from the overlapping area of the internal electrodes, and the width of the correction electrode is larger than the width of the internal electrode. The laminated capacitor is formed so as to be narrow and within the width of the internal electrode, and the correction electrode is drawn out to one end face of the opposite two end faces of the sintered body. .