JPH04139710A - Laminated ceramic capacitor and manufacture thereof - Google Patents

Abstract

PURPOSE:To easily and freely adjust the capacitance of a laminated ceramic capacitor by making each adjacent internal electrodes facing each other to have at least one pattern which does not affect the capacitance while the electrodes have an overlapped part. CONSTITUTION:This laminated ceramic capacitor is constituted by piling up seven green sheets and the six layers from the first layer to the sixth layer are formed by alternately piling up inductive ceramic green sheets (a) and (b) so that their crossing areas can becomes S0. The seventh layer is put on the sixth layer in such a state that the seventh layer is shifted from the sixth layer by t in the length direction so that the crossing area with the sixth layer can becomes S. After the green sheets are piled up, they are press-contacted with each other and laminated body is cut into each block along cutting lines aligned to each other from the first sheet to the sixth sheet. When the green sheets are piled up in such a way, sections where internal electrodes which are originally to be connected to different electrodes on the same electrode-side end face are led out are formed on one or both end faces of the sixth and seventh layers from the top. However, since the sixth and seventh layers are short-circuited with each other, these parts have the same potential and no capacitance is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multilayer ceramic capacitor and a method for manufacturing the same.

[Prior Art] Conventionally, multilayer ceramic capacitors have thin dielectric layers printed with internal electrodes A and B, indicated by 2 and 3 in FIGS. 5 and 6, which are alternately opposed to each other as shown in FIG. One end of these two types of electrodes was alternately led out to different end faces of the capacitor body, and connected to the external electrode 1 in the figure formed there. In this case, adjacent internal electrodes overlapped with each other in a manner as shown in FIG. 6, so that even if there was some positional deviation in the width direction, the overlapping area did not change. That is, A, 82 whose width dimension was intentionally changed somewhat.
By preparing various patterns and stacking AlB sheets alternately, even if there is some deviation in the width direction, the S
. The size of the capacitance was kept constant by not changing the area of the part shown in (cross-hatch part).

A method for manufacturing such a multilayer ceramic capacitor is generally as follows.

First, a dielectric porcelain raw material powder and an organic binder are mixed to form a slurry, and the resulting slurry is continuously and thinly applied onto a long base film using a coating method such as a doctor blade method to form a sheet. dry. After drying, the sheet is peeled off from the base film and cut into a predetermined size to form a ceramic green sheet. Next, on this green sheet, a large number of sheets are prepared by screen printing a plurality of internal electrodes each having the same type of pattern A or B for each pattern A and B.

The internal electrodes are printed in such a way that a plurality of rectangular patterns that form two internal electrodes that are continuous with the adjacent element body are arranged at equal intervals on the sheet having either pattern.

Next, green sheets on which electrode patterns A and B are printed are stacked in the following manner. That is, first place a green sheet with no internal electrodes printed on it, place a green sheet with pattern A (or pattern B) internal electrodes printed on it, and then place pattern B (or pattern A) internal electrodes on top of it. A green sheet printed with is placed, and this is repeated to alternately stack pattern A sheets and pattern B sheets. 2 of the pattern spacing of pattern B on the adjacent sheet
Layer them one after another so that the equal dividing lines (axes of symmetry) overlap, and finally layer the green sheets on which no internal electrodes are printed.

The green sheets stacked in this manner are pressed together to integrate them. This crimping is carried out by aligning the bisectors of the rectangular pattern and the pattern interval so that the ends of the 82 types of internal electrodes are alternately drawn out on both end faces in the longitudinal direction of the cut element. The chip element is then cut at the position where the internal electrodes are exposed alternately on the opposing end faces. After applying external electrode paste to both longitudinal end surfaces of the thus obtained chip element, that is, the surfaces from which the internal electrodes of the laminated sheets are alternately led out, the paste is fired.
A multilayer ceramic capacitor as shown in Figure 5 was obtained.

The acquired capacitance of such a multilayer ceramic capacitor is determined by the intersection area of internal electrodes facing each other with a dielectric layer in between and the thickness of the dielectric layer. Therefore, when trying to change the capacitance slightly, one of the things to do is to make sure that the intersection area S of at least one pair of internal electrodes of the plurality of opposing pairs of internal electrodes is larger than that of all other pairs, as shown in FIGS. 7 and 8. Internal electrode intersection area S. Further prepare a green sheet on which a third pattern of internal electrodes C (4 in FIG. 8) that is slightly smaller (or larger) is printed, and add this to the patterned sheet of the green sheet laminate. When I used it in place of the sheet at the end of the layer (4 in Figure 7), I obtained a slightly smaller (or larger) change in capacitance.

Second, as shown in the stacked cross-sectional view in Figure 9, a thick green sheet with a different thickness from other sheets is prepared, and used as a part of the sheet on which the internal electrodes are printed, and the distance between the opposing electrodes is adjusted. That is, by changing the thickness of the dielectric layer, a changed capacitance was obtained.

[Problems to be Solved by the Invention] In the capacitance adjustment method according to the above-mentioned conventional technology, depending on the capacitance value to be adjusted, green sheets printed with several types of internal electrode patterns or several types of green sheets with different thicknesses are used. Each requires a large number of sheets with different patterns or a large number of different thicknesses. Therefore, management of these many sheets has become complicated and extremely troublesome. Also,
Fine adjustment of capacitance was extremely difficult, resulting in a significant drop in productivity.

The present invention solves the above-mentioned problems of the conventional technology, and achieves at most A
, 82 basic patterns can be printed (-) of any desired static pattern produced using only green sheets, i.e., without using green sheets with different patterns or different thicknesses. To provide a method for manufacturing a multilayer ceramic capacitor in which capacitance can be easily and freely adjusted without preparing a multilayer ceramic capacitor having capacitance or sheets having a plurality of different patterns or thicknesses. The purpose is to

[Means for solving the problem and the former inventor of the present invention,
As a result of research aimed at achieving the above goal, we found that by preparing at most two types of green sheets printed with many identical patterns, it is possible to freely create multilayer ceramic capacitors with capacitances of various sizes. We have developed a method.

Conventionally, an internal electrode pattern formed on a green sheet is a rectangular pattern divided into two equal parts at the center, which causes various problems in adjusting capacitance. In the present invention,
A green sheet with internal electrode patterns arranged at equal intervals, which does not need to be divided into two in the center, can be made into pattern A at most.
Prepare only two types: pattern B and pattern B. When these green sheets are stacked, most of the sheets are alternately shifted by a predetermined distance as usual so that the intersecting area of the internal electrodes on adjacent sheets is the same for every pair. Then, if necessary, at least one pair of green sheets are stacked at a different interval from the predetermined interval so that the internal electrode intersection area is different from other pairs. The present inventors have discovered that by doing this, it is possible to easily finely adjust the capacitance without preparing a plurality of different internal electrode patterns or multiple types of green sheets with different thicknesses as in the past, and have arrived at the present invention. The reason why the above description includes the case where there is only one type is because pattern A may be the same as pattern B.

That is, firstly, the present invention provides a multilayer ceramic capacitor having a basic structure in which internal electrodes for obtaining capacitance are alternately opposed to each other with thin dielectric layers in between, and the internal electrodes for obtaining capacitance are opposed to each other. A laminated ceramic formed of patterns, characterized in that there is at least one pattern that has an overlapping portion but does not affect capacitance between opposing and adjacent internal electrodes in the laminated body. capacitor; and secondly, 2 in the middle
A green sheet in which a plurality of internal electrode patterns A are arranged, which are not equally divided, and a green sheet in which a plurality of internal electrode patterns B, which are not divided into two in the center, are arranged, are alternately shifted by a predetermined interval so that adjacent internal electrodes are arranged at a constant distance. Area S
. If necessary, at least one green sheet for capacitance adjustment is formed so that the overlap between adjacent internal electrodes has the above-mentioned area S. A multilayer ceramic capacitor characterized in that green sheets having a pattern A or a pattern B are stacked in the same A1B alternating order as other green sheets, shifted by an interval different from the predetermined interval so as to have an area S different from the predetermined interval. The present invention provides a method for manufacturing.

In the present invention, first, a plurality of internal electrodes in one type of rectangular pattern, which do not need to be divided into two equal parts at the center, are arranged on a ceramic green sheet. One or two types of green sheets printed with mutually different internal electrode patterns are sufficient. Next, these sheets are stacked so that a predetermined capacitance can be obtained by alternately shifting them at a predetermined constant interval so that the intersecting area of the internal electrodes on adjacent sheets is the same for every pair. However, if necessary, for fine adjustment of the capacitance, at least one layer of sheets is provided, which are stacked one on top of the other at a distance equal to or more than the above-mentioned interval so that the intersecting area of the internal electrodes is different from that of the other pairs. After the laminate thus laminated is crimped, it is cut into individual chips at positions where part of the internal electrodes are led out. Furthermore, an external electrode is formed on the internal electrode leading side of the cut element body, and this is fired to manufacture the multilayer ceramic capacitor of the present invention.

The plurality of internal electrode patterns formed on the ceramic sheet in the present invention are rectangular patterns that do not need to be divided into two equal parts at the center. In other words, this corresponds to one layer of internal electrodes in one multilayer ceramic capacitor element, which is one of the major differences from conventional technology, which corresponds to the size of two elements. It is.

In addition, originally only one type of internal electrode rectangular pattern is required to be formed on the ceramic sheet, but when the ceramic sheets are stacked, the width direction of the area where adjacent internal electrodes overlap, which becomes the capacitance acquisition area. In order to make it easier to absorb errors in capacitance caused by positional misalignment, we prepared a 2N model with a different XJ method in the width direction of the rectangular pattern, and placed these two types of internal electrodes on different greens. We created two types of ceramic sheets with multiple formations on the sheet,
The usual method is to stack them alternately.

In the multilayer ceramic capacitor of the present invention, there may be a portion where adjacent internal electrodes overlap but are not involved in determining the size of the acquired capacitance. One is the case where the end portions of adjacent internal electrodes on the same side are both led out to the same side, and the patterns have portions overlapping each other. In this case, no electrostatic capacitance is generated in the overlapping portion, and the lead-out portion contributes to the fixing strength of the external electrode in order to increase the adhesion strength with the external electrode formed there on the internal electrode lead-out side. The other case is when one of the adjacent internal electrodes is not led out to any side surface when the element is cut (fourth
(See the 6th layer from the top of the figure). In this case, the internal electrode that is not led out to either side is used as a common electrode, and two capacitors are connected in series together with the counter electrode.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

However, the scope of the present invention is not limited by the following examples.

[Example 1] A method for manufacturing a multilayer ceramic capacitor according to the present invention will be explained based on the multilayer ceramic capacitor shown in FIGS. 1 and 2.

FIG. 1 shows an example of an internal electrode pattern formed on a dielectric ceramic green sheet. Figure 1(a) and (
b) shows four capacitor bodies, and 2 in the figure
and 3 are internal electrodes of pattern A and pattern B, respectively. 2 (pattern A) width to 3 (pattern B)
) By making the width narrower, it is possible to easily absorb errors caused by misalignment in the width direction that occurs when the sheets are stacked.

6 is the cutting margin when cutting each piece. 7 is the center line of this cut mark, and one end of the internal electrode pattern is formed up to this position. A plurality of continuous capacitor bodies are manufactured by alternately stacking the two types of dielectric ceramic green sheets of (a) and (b) above.

Next, how to stack the sheets will be explained based on FIG. 2. FIG. 2 is a longitudinal sectional view of the stacked sheets. S in the figure. and S are opposing portions of adjacent internal electrodes in the stacked sheets, and this will be referred to as the intersection area. The number of stacked green sheets in this example is 7 layers, and the 6th layer from the top is
The intersecting area of the dielectric ceramic green sheets of a) and (b) is S. Alternately stack (a) and (b) so that For the seventh layer, the sheets are shifted by a length Δt in the longitudinal direction and overlapped so that the intersection area with the sixth layer is S. After the layers are laminated, they are crimped and cut individually along the overlapping cut edges up to the 6th layer from the top.

By overlapping in the above method, the sixth and seventh layers from the top have a portion on one or both end faces of the same electrode side where the internal electrodes to be connected to the original electrodes are led out. However, in this part, 6
Since the 7th layer and the 7th layer are short-circuited, they have the same potential and no capacitance occurs.

[Example 2] FIG. 3 shows another laminated form of dielectric ceramic green sheets in the multilayer ceramic capacitor of the present invention.

FIG. 3 is a longitudinal cross-sectional view of the conductive pattern of the dielectric layer. In this example, the conductive pattern (a
The internal electrodes of ) and (b) are stacked so that they overlap in two places, and then cut at the overlapping part. Since the body layer is drawn out, there is also the effect that the adhesion strength with the external electrode formed on the side surface is increased.

[Example 3] FIG. 4 shows still another stacked mode of dielectric ceramic green sheets in the multilayer ceramic capacitor of the present invention.

FIG. 4 is a longitudinal cross-sectional view of the conductive pattern of the dielectric layer. In the figure, the internal electrode pattern 5 in the sixth layer from the top is a common electrode that connects two capacitors in series, each of which has four layers, by overlapping the left side and right side of the internal electrode pattern in the seventh layer in the figure. It has become.

In this embodiment, the intersection area is S. A five-layer internal electrode pattern having a cross area S and a two-layer internal electrode pattern having an intersecting area S and S' are combined. Therefore, by stacking the sheets in the combination as in this embodiment, variations in pattern stacking accuracy can be absorbed, and minute changes in capacitance can be reproduced with high precision.

[Effects of the invention] With the advent of the present invention, it is no longer necessary to prepare multiple sheets of different types by changing the pattern or thickness of the internal electrodes formed on the conductive ceramic green sheet, and the hassle in management has been eliminated. . In addition, fine adjustment of the capacitance of multilayer ceramic capacitors can now be easily and widely performed, resulting in a significant improvement in productivity. Furthermore, since the influence of overlay accuracy when overlapping the sheets has become extremely small, manufacturing accuracy has also been significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing an example of an internal electrode pattern formed on a dielectric ceramic green sheet of the present invention, and FIG. 1 (a) and (b) are internal electrodes A and B having different patterns. It is a figure showing each four pieces. FIG. 2, FIG. 3, and FIG. 4 illustrate the state in which the dielectric ceramic green sheets in the present invention are stacked, and are side sectional views in the longitudinal direction of the stacked sheets. FIG. 5 is a side cross-sectional perspective view of a multilayer ceramic capacitor manufactured by a conventional method. FIG. 6 is a plan view showing the arrangement of internal electrodes in FIG. 5. FIGS. 7 and 8 are a cross-sectional view and a plan view showing the arrangement of internal electrodes of a conventional laminated dielectric layer in which capacitance is adjusted by adjusting intersecting areas facing each other. FIG. 9 is a cross-sectional view of a conventional laminated dielectric layer in which green sheets of different thicknesses are used to adjust capacitance. Explanation of symbols 1...External electrode 2...Internal electrode A 3...Internal electrode B 4...Internal electrode C 5...Common Electrode 6... Cutting margin 7... Cutting position center line so, s, s'... Intersection area To, T... Dielectric layer thickness △t... Travel distance patent applicant: Taiyo Yuden Co., Ltd. Representative: Masahiko Maruoka, patent attorney Fig. 7...vl disconnection, falling snow, tortoise Fig. 2...Internal 1 + Yuzu A 3...Internal electric @-B 5・･････････････････････････････････････････････････････････ Denmochi 2... Uchigo Densei A 3, Inner Dengo B 4... Give F1 section C 6. Cutting allowance So, S-intersection area ゛To, T ・R [1 layer thickness

Claims (2)

[Claims] (1) A multilayer ceramic capacitor having a basic structure in which internal electrodes for obtaining capacitance are alternately opposed to each other with thin dielectric layers in between, and the internal electrodes for obtaining capacitance are formed from opposing patterns. A multilayer ceramic capacitor characterized in that internal electrodes in a multilayer body that are opposite to each other have at least one pattern that has an overlapping portion but does not affect capacitance. (2) A green sheet with a plurality of internal electrode patterns A that is not divided into two equal parts in the center and a green sheet with a plurality of internal electrode patterns B that are not divided into two in the center are arranged adjacent to each other, alternately shifted by a predetermined interval. The internal electrodes are stacked so that they overlap each other with a constant area S_0, and if necessary, at least one layer is used as a green sheet for capacitance adjustment, so that the overlap between adjacent internal electrodes has an area S different from the area S_0. As shown in FIG.
, B. A method for manufacturing a multilayer ceramic capacitor, characterized in that the layers are arranged in an alternating order.