JPH08316086A - Laminated ceramic electronic component - Google Patents

Abstract

PURPOSE: To provide a laminated ceramic electronic component characterized in that the crack of the internal electrode boundary by the internal stress caused by the thermal expansion difference between its ceramic layer and electrode layer. CONSTITUTION: Internal electrodes 12a-12g are laminated in the interior of a sintered ceramic body 10 and dummy electrodes 15 made of the same material as that of the internal electrode are disposed with fixed spacings on the outside of the internal electrodes. The dummy electrodes 15 are formed on a stress relaxation layer 10c. The electrodes 12a-12g are formed on an element part 10b and outer layer part 10a is composed of a ceramic layer 14. The thermal shrinkage of the layer 10c is medial between those of the parts 10b and 10a. Therefore, the internal stress by the thermal shrinkage difference between the parts 10b and 10a is relaxed in the temp. falling process after sintering.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monolithic ceramic electronic component, and more particularly to a monolithic ceramic electronic component in which internal stress caused by a difference in thermal expansion between a ceramic layer and an electrode layer is relaxed.

[0002]

2. Description of the Related Art As a kind of conventional monolithic ceramic electronic component, the structure of a monolithic capacitor will be described with reference to FIG.

The multilayer capacitor 70 is a ceramic sintered body 7 made of a dielectric ceramic such as barium titanate.
1 is used. Inside the ceramic sintered body 71, a plurality of internal electrodes 72a to 72h are formed so as to overlap with each other with a ceramic layer interposed therebetween. On one end surface 71a of the ceramic sintered body 71, the internal electrodes 72a, 72
The external electrode 75a is formed so as to be electrically connected to the c, 72f, and 72h, and the external electrode 75b is formed on the other end surface 71b so as to be electrically connected to the internal electrodes 72b, 72d, 72e, and 72g. Are formed. Internal electrode 7
2a to 72h are usually made of a metal material such as Ni, Pd, or Ag-Pd alloy. And the internal electrode 7
2a to 72h and the ceramic layer 73 interposed between each internal electrode constitute a capacitance extracting portion.

In the multilayer capacitor 70 as described above, for convenience sake, the capacitance extracting portion is referred to as an element portion 70b, and the ceramic layers 74, 74 laminated in the vertical direction of the element portion 70b.
Are referred to as outer layer portions 70a and 70a.

In manufacturing the multilayer capacitor 70, a plurality of ceramic green sheets for forming the outer layer portion 70a and a plurality of element-forming ceramic green sheets formed by printing a conductive paste on an internal electrode pattern. Are laminated, pressure-bonded, and fired to obtain a ceramic sintered body 7
1 is formed, and external electrodes 75a and 75b are further formed on both end surfaces of the ceramic sintered body 71.

[0006]

As described above, the ceramic sintered body 71 is formed by firing a laminated body of ceramic green sheets.

In the firing process of the ceramic sintered body 71, the generation of internal stress due to the difference in thermal expansion coefficient between the ceramic layer and the internal electrode becomes a problem. That is, the coefficient of thermal expansion of the ceramic layer containing barium titanate as a main component is smaller than the coefficient of thermal expansion of the internal electrodes 72a to 72h containing metal as a main component. Therefore, as schematically shown in FIG. 8, in the temperature decreasing process after firing, the shrinkage amount of the ceramic layer 74 of the outer layer portion 70a is determined by the internal electrode 72 of the element portion 70b.
It is smaller than the contraction amount of a to 72h. Therefore, in particular, the shear stress is concentrated along the interface between the outermost internal electrodes 72a and 72h and the outer ceramic layers 74 and 74, and the outermost internal electrodes 72a and 72h indicated by X in the drawing are concentrated.
There were cases where peeling or cracks occurred at the end of the. Such a tendency becomes remarkable as the ceramic layer 73 between the internal electrodes becomes thin in order to increase the capacity and the total thickness of the internal electrodes becomes relatively large, which has become a serious problem.

An object of the present invention is to provide a monolithic ceramic electronic component in which internal stress caused by a difference in thermal expansion between a ceramic material and an electrode material does not cause cracks or the like at the interface between the internal electrode and the ceramic layer. is there.

[0009]

The laminated ceramic electronic component according to the present invention has a ceramic sintered body. In this ceramic sintered body, the outer layer portion, in order along the thickness direction,
The element portion and the outer layer portion are configured. The element portion has a plurality of internal electrodes laminated in the thickness direction of the ceramic sintered body via ceramic layers having a predetermined thickness. Further, the ceramic sintered body has at least one pseudo structure formed so as not to be exposed on the outer surface of the sintered body between the element portion and the outer layer portion in order to relieve internal stress caused by the difference in thermal expansion. A stress relaxation layer having an electrode is provided.

The pseudo electrode does not function as an electrode and is intended to be a layer formed of the same material as the internal electrode or a material having a thermal expansion coefficient intermediate between that of the internal electrode material and ceramic. To do.

Further, in the multilayer ceramic electronic component according to the limited aspect of the present invention, the pseudo electrodes of the stress relaxation layer are arranged on the outermost side with a distance larger than the distance between the internal electrodes of the element section. It is formed further outside the electrode.

Further, in the laminated ceramic electronic component according to another limited aspect of the present invention, the pseudo electrode of the stress relaxation layer is formed thinner than the thickness of the internal electrode. Since the pseudo electrode does not function as an electrode, it does not need to maintain conductivity and can be thinner than the internal electrode.

Further, in the multilayer ceramic electronic component according to another limited aspect of the present invention, the stress relaxation layer has a plurality of pseudo electrodes having different plane areas. The plurality of pseudo electrodes are arranged with a predetermined distance so that the plane area decreases in order from the element portion side of the ceramic sintered body toward the outer layer portion side.

The number of the pseudo electrodes is not particularly limited.
Moreover, the electrodes may be arranged such that the plane area of each electrode decreases in order toward the outer layer side, or the plane area decreases for every two layers, for example, the plane area decreases. You may arrange so.

Further, in a monolithic ceramic electronic component according to another aspect of the present invention, a plurality of internal parts are provided in a plane parallel to the internal electrodes which are outwardly separated by a predetermined distance from the internal electrodes arranged at the outermost part. At least one pseudo electrode is formed in a planar shape different from the planar shape in which the electrodes overlap. As for the planar shape of the pseudo electrode, various shapes such as an arbitrary shape, for example, a linear shape that is integrally continuous, or a shape that is arranged in a dotted manner in a plane parallel to the internal electrode can be applied.

[0016]

In the conventional multilayer capacitor shown in FIG. 8, cracks are generated at the outermost internal electrode 72.
It is concentrated in the vicinity of the end portions of a and 74h, and hardly occurs at the interface between the internal electrode inside the element portion and the ceramic layer between them. Inferring from such a situation, in the element part, the internal electrodes 72a to 72h are arranged on both surfaces of the ceramic layer 73 which is thinner than the outer layer part, and the thin ceramic layer 73 is formed to some extent as the internal electrodes contract. It is considered that the shear stress between the two is reduced by following and contracting. On the other hand, regarding the relationship between the outer layer portions 70a, 70a and the inner electrodes 72a, 72h arranged in the outermost layers, the ceramic layers 74, 74 of the outer layer portion are formed relatively thick, and one surface thereof is in contact with the outside air, The internal electrodes 72a and 72h are formed only on the other surface. Therefore, the internal electrodes 72a, 7 formed on one surface are
The heat shrinkage force transmitted from 2h to the ceramic layer 74 is smaller than the heat shrinkage force transmitted to the ceramic layer 73 of the element portion in which the internal electrodes 72a to 72h are laminated on both surfaces, and the ceramic layer 74 having a large layer thickness is Since the rigidity is higher than that of the thin ceramic layer 73 of the element part, the internal electrode 72
a, 72h does not shrink sufficiently, and therefore the shearing stress generated between the two becomes large, and it is considered that cracks are concentrated at the ends of the internal electrodes 72a, 72h with a particularly large amount of heat shrinkage. To be

From the above consideration, the laminated ceramic electronic component according to the present invention has the stress relaxation layer between the element portion and the outer layer portion. First, when a pseudo electrode is provided inside the stress relaxation layer, a structure in which the ceramic layer is sandwiched between the pseudo electrode and the inner electrode located at the outermost layer of the element portion can be formed. Therefore, the ceramic element sandwiched between the pseudo electrode and the outermost inner electrode receives heat contraction force from both surface sides by the pseudo electrode and the inner electrode, and the heat shrinks to some extent by following both electrodes. The internal stress caused by the difference in thermal expansion (difference in thermal contraction) is relaxed. Therefore, the shear stress on the surface of the innermost electrode of the outermost layer is reduced, and the generation of cracks is prevented. This action can be obtained even when the pseudo electrode is formed in an arbitrary shape such as a linear shape or a scattered shape.

Further, if the distance between the pseudo electrode and the innermost outer electrode of the element portion is increased, that is, if the thickness of the ceramic layer interposed between the pseudo electrode and the innermost outer electrode is increased, this ceramic layer The rigidity is intermediate between the ceramic layer of the outer layer portion and the ceramic layer of the element portion. Therefore, the stress relaxation layer performs an intermediate heat contraction operation between the outer layer portion and the element portion. Thereby, the shear stress caused by the thermal contraction acting between the outer layer portion and the element portion is relaxed, and the generation of cracks at the end portion of the internal electrode located in the outermost layer of the element portion is suppressed.

If the thickness of the pseudo electrode formed outside the internal electrode arranged in the outermost layer of the element portion is made smaller than the thickness of the internal electrode, the thin pseudo electrode and the internal electrode of the outermost layer are separated from each other. The rigidity of the ceramic layer interposed therebetween is relatively increased with respect to the pseudo electrode. Therefore, the heat shrinkage applied from the internal electrode and the pseudo electrode is suppressed, and the shearing force between the outer layer portion and the element portion is relaxed similarly to the above.

Furthermore, when the pseudo electrodes are arranged so that the plane area decreases in order from the element portion side toward the outer layer portion side, the thermal contraction amount of the stress relaxation layer is equal to the element portion toward the outer layer portion side. It gradually decreases to the same level as the outer layer. This disperses the internal stress between the outer layer portion and the element portion, and prevents the occurrence of cracks on the surface of the internal electrode arranged in the outermost layer of the element portion.

[0021]

EXAMPLES The present invention will be clarified by describing examples of the present invention with reference to the drawings.

First Embodiment FIG. 1 is a sectional structural view of a multilayer capacitor according to a first embodiment of the present invention, and FIG. 2 is a sectional structural view taken along the line Y--Y. The multilayer capacitor 10 is composed of a ceramic sintered body 11 and external electrodes 17, 17 formed on both end surfaces of the ceramic sintered body. In FIG. 1, only one external electrode 17 is shown for convenience of drawing.

The ceramic sintered body 10 is manufactured as follows. First, for the outer layer portion 10a, a ceramic green sheet made of a reduction resistant ceramic as a raw material is formed into a predetermined shape.

Further, for the stress relaxation layer 10c, the same ceramic green sheet as described above and Ni on the surface thereof are used.
Five sheets of ceramic green sheets each having a pseudo electrode formed by printing the paste thinner than the thickness of the internal electrode are prepared.

Further, for the element portion 10b, 201 sheets of electrode sheets are prepared in which the Ni paste is printed on the surface of the same ceramic green sheet as described above to form internal electrodes.

Then, as shown in FIG. 1, from the lower layer side,
Ceramic green sheets for the outer layer portion are laminated, and on the surface thereof, five ceramic green sheets printed with pseudo electrodes for the stress relaxation layer and five unprinted plain green sheets are alternately laminated. Further, 201 electrode sheets for the element portion are laminated on the surface thereof.
Further, similarly to the above, a ceramic green sheet for the stress relaxation layer and a ceramic green sheet for the outer layer portion are laminated.

Then, the laminated body in which the ceramic green sheets are laminated is pressure-bonded and cut into each chip size. Then, the cut chip laminated body is fired under reducing conditions. After firing, the temperature was lowered to room temperature to obtain a ceramic sintered body 10.

The ceramic sintered body 10 has an outer layer portion 10a, a stress relaxation layer 10c, and an element portion 10 along its thickness direction.
b, the stress relaxation layer 10c and the outer layer portion 10a are integrally laminated. A plurality of stress relaxation layers 10c and 10c are formed outside the internal electrodes 12a and 12g formed on the outermost layers of the element portion 10b, with a ceramic layer 16 interposed therebetween, five in this example. The thickness of the ceramic layer 16 is
It is thicker than the ceramic layer 13 between the internal electrodes of the element portion 10b, and is formed to have twice the thickness in this example. Further, the pseudo electrode 15 is formed in the same plane shape as the shape of the planes of the plurality of internal electrodes 12a to 12g that overlap each other. Further, the film thickness thereof is formed thinner than the film thickness of the internal electrodes 12a to 12d.

The ceramic sintered body 1 manufactured in this way
In No. 0, no cracks were found on the surfaces of the outermost inner electrodes 12a and 12g or near the end faces. This is because the stress relaxation layer 10c has a relatively large thermal contraction operation of the element portion 10b in which a large number of internal electrodes are laminated, and a relatively small thermal contraction of the outer layer portion 10a composed of the relatively thick ceramic layer 14. By performing the intermediate heat shrinking operation of the shrinking operation, the heat shrinkage amount of the ceramic sintered body 10 changes stepwise from the element portion 10b toward the outer layer portion 10a, and the heat of the element portion 10b and the outer layer portion 10a is reduced. This is because the concentration of internal stress due to the difference in shrinkage amount was relaxed.

Second Embodiment FIG. 3 is a sectional structural view of a ceramic sintered body of a multilayer capacitor according to a second embodiment of the present invention, and FIG. 4 is its planar structure. Note that FIG. 4 schematically shows the shapes of the internal electrodes and the pseudo electrodes of the ceramic sintered body 31.

The ceramic sintered body 31 of the multilayer capacitor 30 according to the second embodiment differs from that of the first embodiment only in the structures of the stress relaxation layers 30c and 30c, and the element portion 30 is different.
b, the structure of the outer layer portion 30a is similar to that of the first embodiment. Therefore, the internal electrodes 32a to 32 of the element portion 30b are
f, the structure of the ceramic layer 33 and the ceramic layer 34 of the outer layer portion 30a are the same as those of the internal electrodes 12a to 12g, the ceramic layer 13 and the outer layer portion 10a of the element portion 10b of the first embodiment.
Since the structure is the same as that of the ceramic layer 14, the description thereof is omitted here.

The stress relaxation layer 30 is formed by laminating five kinds of pseudo electrodes 35a to 35e having different plane areas as a set of two electrodes having the same size. For example, each of the pseudo electrodes 35a to 35e is formed such that the length of one side is reduced by 10%. A ceramic layer 36 is interposed between the pseudo electrodes 35a to 35e. The plurality of pseudo electrodes 35a to 35e having different sizes are arranged from the innermost electrode 32a, 32f of the element portion 30b to the outer layer portion 30a, 30a.
Are stacked in a pyramid shape toward. Even when the ceramic laminated body provided with such stress relaxation layers 30c, 30c is fired and cooled, cracks are not generated in the vicinity of the surfaces of the outermost internal electrodes 32a, 32f of the obtained ceramic sintered body 31. I couldn't see it.

In the stress relaxation layer 30c having the pseudo electrodes 35a to 35e arranged in the shape of such a pillar, the positions of the ends of the pseudo electrodes 35a to 35e are the ceramic sintered body 3.
By being configured differently toward the central portion of No. 1, the locations where stress concentration occurs are dispersed, and as a result, stress concentration is relaxed only near the ends of the innermost outer electrodes 32a, 32f. I was able to do it.

Third Embodiment FIG. 5 is a sectional structural view of a ceramic sintered body 51 of a multilayer capacitor 50 according to a third embodiment, and FIG. 6 is a plan structural view thereof. Compared to the first embodiment, the ceramic sintered body 51 according to the third embodiment has stress relaxation layers 50c, 50.
Only the configuration of c is different, and the internal electrodes 52a to 52f of the element portion 50b, the ceramic layer 53 and the outer layer portion 50a,
The structure of the ceramic layers 54, 54 of 50a is the same as the structure of the internal electrodes 12a to 12g of the element part 10b, the ceramic layer 13, and the ceramic layers 14, 14 of the outer layer parts 10a, 10a in the first embodiment. The description of is omitted.

The stress relaxation layer 50c is formed on the surface of a ceramic green sheet made of reduction resistant ceramics as a raw material by N
By printing i paste, the grid-like pseudo electrodes 55
It is configured by laminating 10 ceramic green sheets having the above.

The ceramic sintered body 51 obtained by firing and lowering the temperature of the laminated body in which the stress relaxation layers 50c and 50c are laminated is the surface of the internal electrodes 52a and 52f formed in the outermost layer of the element portion 50b. No cracks were found in the vicinity.

The stress relaxation layer 50c is composed of the internal electrodes 52a-5.
The pseudo electrodes 55 are discontinuously formed in the plane parallel to 2f. In the plane including such a discontinuous pseudo electrode 55, like the element portion 50b, a continuous internal electrode 5 is formed.
As compared with the layer including 2a to 52f, the heat shrinking operation in the horizontal direction is relatively relaxed. Therefore, the thermal contraction amount gradually decreases in the order of the element portion 50b, the stress relaxation layer 50c, and the outer layer portion 50a, and accordingly, the internal stress in the horizontal direction is dispersed, and the outermost layer of the element portion 50b is dispersed. Internal electrode 52
The stress concentration on the surfaces of a and 52f is reduced.

From this point of view, the pseudo electrode 55 is used.
The shape of is not limited to the grid shape as shown in FIG. 6, and any shape such as slit shape, dot shape, and broken line shape can be applied. Further, the number of stacked layers can be appropriately set according to the shape of the ceramic sintered body or the like.

The pseudo electrodes formed on the stress relaxation layers of the first to third embodiments are preferably made of the same material as the internal electrodes, but have a coefficient of thermal expansion between the internal electrodes and the ceramic. Other materials may be used as long as the materials have them, and the number of stacked layers can be appropriately adjusted.
The material of the internal electrodes is not limited to Ni, but Pd, Ag—Pd alloy, or the like may be used.

Further, the structures of the stress relaxation layers according to the above-mentioned first to third embodiments can be combined with each other.
That is, inside the stress relaxation layer, the thin pseudo electrode layer according to the first embodiment, the pseudo electrode with reduced plane area according to the second embodiment, and the discontinuous pseudo electrode according to the third embodiment. And may be appropriately combined.

[0041]

As described above, in the monolithic ceramic electronic component according to the present invention, for example, the stress relaxation layer is provided between the outer layer portion having a small heat shrinkage and the element portion having a relatively large heat shrinkage. By doing so, it is possible to prevent cracks and peeling near the interface between the internal electrode and the ceramic layer due to internal stress caused by the difference in thermal expansion, and it is possible to obtain a highly reliable multilayer ceramic electronic component.

[Brief description of drawings]

FIG. 1 is a sectional structural view of a multilayer capacitor according to a first embodiment of the present invention.

FIG. 2 is a side sectional structural view of the multilayer capacitor shown in FIG. 1 taken along a section line Y-Y.

FIG. 3 is a sectional structural view of a multilayer capacitor according to a second embodiment of the present invention.

4 is a plan view of the multilayer capacitor shown in FIG.

FIG. 5 is a sectional structural view of a multilayer capacitor according to a third embodiment of the present invention.

6 is a plan view of the multilayer capacitor shown in FIG.

FIG. 7 is a sectional structural view of a conventional multilayer capacitor.

FIG. 8 is an explanatory view showing a heat shrinkage state of the multilayer capacitor shown in FIG. 7 after sintering and at the time of temperature decrease.

[Explanation of symbols]

10, 30, 50 ... Multilayer capacitor 11, 31, 51 ... Ceramic sintered body 10a, 30a, 50a ... Outer layer portion 10b, 30b, 50b ... Element portion 10c, 30c, 50c ... Stress relaxation layer 12a-12g, 32a-32f , 52a to 52f ... Internal electrodes 15 to 15, 35a to 35e, 55 ... Pseudo electrodes 13, 16, 33, 36, 53, 56 ... Ceramic layers

Claims (5)

[Claims] 1. A monolithic ceramic electronic component having a ceramic sintered body, wherein the ceramic sintered body comprises an outer layer portion, an element portion, and an outer layer portion in order along the thickness direction. The portion has a plurality of internal electrodes laminated in the thickness direction of the ceramic sintered body via a ceramic layer having a predetermined thickness, and further, in order to relieve internal stress caused by a difference in thermal expansion, A multilayer ceramic comprising a stress relaxation layer having at least one pseudo electrode formed between the element portion and at least one of the outer layer portions so as not to be exposed on the outer surface of the sintered body. Electronic components. 2. The stress relieving layer further includes a plurality of internal electrodes, the inner electrode being disposed on the outermost side in the thickness direction of the ceramic sintered body, among the plurality of internal electrodes. The multilayer ceramic electronic component according to claim 1, further comprising pseudo electrodes formed with a large interval. 3. The multilayer ceramic electronic component according to claim 1, wherein the pseudo electrode of the stress relaxation layer is formed thinner than the thickness of the internal electrode. 4. The stress relaxation layer has a plurality of the pseudo electrodes having different plane areas, and the plurality of the pseudo electrodes have a plane area decreasing in order from the element portion side to the outer layer side. 2. The laminated ceramic electronic component according to claim 1, wherein the laminated ceramic electronic component is arranged with a predetermined distance. 5. A plurality of ceramic ceramics are arranged in a plane parallel to the internal electrodes, which is separated from the internal electrodes arranged at the outermost side in the thickness direction of the ceramic sintered body by a predetermined distance toward the outside. 2. The multilayer ceramic electronic component according to claim 1, wherein at least one of the pseudo electrodes is formed so as to have a planar shape different from the planar shape in which the internal electrodes overlap each other.