WO2009093375A1

WO2009093375A1 - Laminated ceramic capacitor and process for producing the laminated ceramic capacitor

Info

Publication number: WO2009093375A1
Application number: PCT/JP2008/071383
Authority: WO
Inventors: Hitoshi Nishimura; Toshihiro Okamatsu
Original assignee: Murata Manufacturing Co., Ltd.
Priority date: 2008-01-24
Filing date: 2008-11-26
Publication date: 2009-07-30

Abstract

When a dielectric ceramic layer is formed of a dielectric ceramic composed mainly of a BaTiO3 ceramic and containing Cu as an accessory component while a capacity-forming electrode contains, for example, Ni as an electroconductive component, due to the nature of Cu which, together with Ni, is likely to form a complete solid solution, during firing, a large amount of Cu contained in the dielectric ceramic is absorbed in the capacity-forming electrode particularly located in the outermost layer resulting in the occurrence of a thickening phenomenon or lowered smoothness in the capacity-forming electrode which sometimes causes delamination or a short circuiting failure. In outer layer parts (9 and 10), non-effective electrodes (11 and 12), which are extended parallel to capacity-forming electrodes (3(B) and 4(B)) located in the outermost layer and contain a metal which, together with Cu, can form a solid solution or an alloy, are formed so that, in the step of firing, Cu is absorbed by the non-effective electrodes (11 and 12) and the probability of causing a thickening phenomenon or a lowering in smoothness is reduced in the capacity-forming electrodes (3(B) and 4(B)) located in the outermost layer.

Description

Multilayer ceramic capacitor and manufacturing method thereof

The present invention relates to a multilayer ceramic capacitor and a method of manufacturing the same, and in particular, includes a plurality of laminated dielectric ceramic layers made of a dielectric ceramic containing a BaTiO ₃ system ceramic as a main component and Cu as a subcomponent. The present invention relates to a multilayer ceramic capacitor and a method for manufacturing the same.

Demand for miniaturization and large capacity for multilayer ceramic capacitors has become increasingly severe in recent years. For this reason, the thickness of the dielectric ceramic layer provided in the multilayer ceramic capacitor is being reduced. However, as the layer becomes thinner, the electric field that can be applied per dielectric ceramic layer increases. Accordingly, as the dielectric ceramic layer is further thinned, higher reliability is required for the dielectric ceramic constituting the dielectric ceramic layer.

As a dielectric ceramic exhibiting such high reliability, a ceramic containing BaTiO ₃ system ceramic as a main component and Cu as a subcomponent has been proposed (for example, see Patent Document 1). According to this dielectric ceramic, material characteristics such as CR product can be improved.

However, as described above, Cu contained as a subcomponent in the dielectric ceramic has the property of being completely dissolved with Ni or the like, and this may cause the following problems.

The capacitor body provided in the multilayer ceramic capacitor includes a plurality of internal electrodes formed therein, that is, a capacitance forming portion in which capacitance forming electrodes are distributed, and an outer layer portion positioned so as to sandwich the capacitance forming portion in the stacking direction. . And, since the thickness of the outer layer portion is usually larger than the thickness of each dielectric ceramic layer located between the capacitance forming electrodes in the capacitance forming portion, the absolute amount of the Cu component contained in the outer layer portion is: More than the absolute amount of Cu component contained in each dielectric ceramic layer located between the capacitance forming electrodes.

For this reason, when the capacitor forming electrode includes, for example, a metal that can form a solid solution or an alloy with Cu such as Ni as a conductive component, the capacitor forming electrode is closest to the outer layer portion, that is, positioned in the outermost layer. In the capacitor forming electrode, the Cu component contained in the outer layer portion causes a larger amount of Cu component than other capacitor forming electrodes. For this reason, the capacitor forming electrode located in the outermost layer is liable to cause a fattening phenomenon and a decrease in smoothness. As a result, delamination and short-circuit defects may be caused in the capacitor body.

In

Patent Document

1, 5 μm is disclosed as the thickness of each dielectric ceramic layer. However, when the thickness is further reduced to 1 μm or less, delamination and short-circuit defects are more likely to occur. It becomes easy to occur, and the above-mentioned fat phenomenon and the problem of reduced smoothness cannot be ignored.
JP 2001-142955 A

Therefore, an object of the present invention is to provide a multilayer ceramic capacitor that can solve the above-described problems and a method for manufacturing the same.

The present invention includes a plurality of laminated dielectric ceramic layers composed of a dielectric ceramic containing BaTiO ₃ ceramic as a main component and Cu as a subcomponent, and a metal that can form a solid solution or alloy with Cu. A capacitor body composed of a plurality of capacitance forming electrodes formed along a specific interface between the ceramic layers, and the capacitor body and a specific one of the capacitance forming electrodes are electrically connected to the outside of the capacitor body. It is first directed to a multilayer ceramic capacitor comprising first and second external terminal electrodes formed on the surface.

In the multilayer ceramic capacitor according to the present invention, in the first aspect, the capacitance forming electrode further includes Cu derived from Cu contained in the dielectric ceramic, and is located in the outermost layer among the plurality of capacitance forming electrodes. The Cu concentration of the capacitance forming electrode is not more than 5 times the Cu concentration of the capacitance forming electrode located in the center.

The “Cu concentration of the capacitance forming electrode located in the center” means that when the number of capacitance forming electrodes is 2n (n is a natural number), the Cu concentration of the nth capacitance forming electrode and the (n + 1) th It is the average value with the Cu concentration of the capacitance forming electrode. When the number of capacitance forming electrodes is 2n + 1, it is the Cu concentration of the (n + 1) th capacitance forming electrode. The “Cu concentration” is defined by the ratio of the peak intensity of Cu to the peak intensity of the conductive metal originally contained in the capacitance forming electrode such as Ni, which is obtained by WDX.

According to a second aspect of the present invention, there is provided a multilayer ceramic capacitor comprising a capacitor main body including a capacitor forming portion in which a capacitor forming electrode is distributed and an outer layer portion positioned so as to sandwich the capacitor forming portion in the stacking direction. Is characterized in that a non-effective electrode including a solid solution or an alloy extending in parallel with the capacitance forming electrode located in the outermost layer and including Cu derived from Cu contained in the dielectric ceramic is formed. It is said.

In the second aspect, the distance between the non-effective electrode and the capacitor forming electrode located on the outermost layer is 0.8 times the thickness dimension of the dielectric ceramic layer between the capacitor forming electrodes or 1 μm, whichever is shorter It is preferable that the thickness is not less than 4 mm and not more than 4 times the thickness of the dielectric ceramic layer between the capacitance forming electrodes.

In the second aspect, it is preferable that the non-effective electrode is formed so as not to be in contact with any of the first and second external terminal electrodes.

In the multilayer ceramic capacitor according to the present invention, the Cu content of the dielectric ceramic is preferably 0.1 to 2 mole parts when the BaTiO ₃ ceramic as a main component is taken as 100 mole parts.

Further, as a metal capable of forming a solid solution or alloy with the above-mentioned Cu, for example, there is Ni.

The present invention is also directed to a method for manufacturing a multilayer ceramic capacitor.

A method of manufacturing a multilayer ceramic capacitor according to the present invention includes a plurality of stacked dielectric ceramic green layers including a dielectric ceramic material containing a BaTiO ₃ ceramic as a main component and Cu as a subcomponent, and Cu and a solid solution or Consists of a plurality of capacitance forming electrodes including a metal capable of forming an alloy and formed along a specific interface between dielectric ceramic green layers, and the capacitance forming portion and the capacitance forming portion are laminated. The outer layer portion is positioned so as to be sandwiched in the direction, and the outer layer portion is formed with an ineffective electrode including a metal that extends in parallel with the capacitance forming electrode positioned in the outermost layer and can form a solid solution or alloy with Cu. A process of preparing a raw capacitor body, a process of firing the raw capacitor body, and a specific one of the capacitance forming electrodes Forming the first and second external terminal electrodes on the outer surface of the capacitor body so as to be connected to each other, and forming a solid solution or alloy with the metal in the firing step, It is characterized in that a part of Cu contained in the dielectric ceramic material in the outer layer portion is absorbed by the ineffective electrode.

Cu contained in the outer layer portion of the capacitor main body tends to diffuse toward the capacitance forming portion in the firing step. According to the present invention, Cu to be diffused is absorbed by the ineffective electrode. Therefore, a large amount of Cu is not absorbed particularly by the capacitance forming electrode located in the outermost layer. As a result, the Cu concentration of the capacitance forming electrode located in the outermost layer is suppressed to 5 times or less than the Cu concentration of the capacitance forming electrode located in the center.

Thus, according to the present invention, by preventing the concentration of Cu in the capacitor forming electrode located in the outermost layer in particular, it is possible to prevent a decrease in thickness and a decrease in smoothness in the capacitor forming electrode. The occurrence of delamination and short-circuit defects caused by these fattening phenomena and smoothness degradation can be suppressed.

For this reason, according to the present invention, the thickness of the dielectric ceramic layer is 5 μm or less per layer, the number of dielectric ceramic layers in the capacitance forming portion is 30 or more, and the thickness of the outer layer portion is the dielectric ceramic layer. The present invention is particularly advantageously applied to a multilayer ceramic capacitor having a thickness of 4 times or more per layer.

In the multilayer ceramic capacitor according to the present invention, the distance between the non-effective electrode and the capacitor forming electrode located in the outermost layer is either 0.8 times the thickness dimension of the dielectric ceramic layer between the capacitor forming electrodes or 1 μm. When the thickness is selected to be not less than the shorter dimension and not more than 4 times the thickness dimension of the dielectric ceramic layer between the capacitance forming electrodes, the above-described effect can be achieved more reliably.

Further, in the multilayer ceramic capacitor according to the present invention, if the non-effective electrode is formed so as not to be in contact with any of the first and second external electrodes, delamination can be made more difficult to occur.

In the multilayer ceramic capacitor according to the present invention, when the Cu content of the dielectric ceramic is selected in the range of 0.1 to 2 mole parts when the BaTiO ₃ based ceramic as a main component is 100 mole parts, The effect of improving the material properties such as the CR product can be obtained with certainty, and the occurrence of delamination can be more reliably suppressed.

1 is a cross-sectional view schematically showing a multilayer ceramic capacitor 1 according to a first embodiment of the present invention. It is a figure which expands and shows the part A of FIG. It is sectional drawing which shows the thing of the raw state of the capacitor | condenser main body 5 prepared in order to obtain the capacitor | condenser main body 5 shown in FIG. It is a figure corresponding to FIG. 2 for demonstrating the 2nd Embodiment of this invention. It is a figure corresponding to FIG. 1 for demonstrating the 3rd Embodiment of this invention. It is a figure corresponding to FIG. 1 for demonstrating the 4th Embodiment of this invention.

Explanation of symbols

1, 1a, 1b Multilayer ceramic capacitor 2 Dielectric ceramic layer or dielectric ceramic

green layer

3, 4 Capacitance forming electrodes 3 (B), 4 (B) Capacitance forming electrodes 3 (C), 4 located in the outermost layer (C) Capacitor forming electrode located in the center 5

Capacitor body

6, 7 External terminal electrode 8

Capacitor forming part

9, 10

Outer layer part

11, 12, 11a, 12a, 11b, 12b Ineffective electrode

FIG. 1 is a cross-sectional view schematically showing a multilayer ceramic capacitor 1 according to a first embodiment of the present invention. FIG. 2 is an enlarged view of a portion A in FIG.

The multilayer ceramic capacitor 1 includes a plurality of laminated dielectric ceramic layers 2 and a plurality of

capacitance forming electrodes

3 and 4 formed along a specific interface between the dielectric ceramic layers 2. A main body 5 is provided.

The dielectric ceramic layer 2 is made of a dielectric ceramic containing a BaTiO ₃ ceramic as a main component and Cu as a subcomponent.

More specifically, this dielectric ceramic is disclosed in the above-mentioned Patent Document 1, and the BaTiO ₃ -based ceramic as the main component is represented by the general formula ABO ₃ . Here, A necessarily includes Ba and may further include at least one of Ca and Sr, and B necessarily includes Ti and may include Zr.

Further, Cu as an accessory component is preferably contained in a range of 0.1 to 2 mole parts, when 100 mole parts of the BaTiO ₃ based ceramic as a main component is taken as 100 mole parts.

The dielectric ceramic is further composed of at least one rare earth element selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Y, Mn, Ni and Mg. At least one of these metals and Si as a sintering aid may be included.

The

capacitance forming electrodes

3 and 4 include a metal that can form a solid solution or an alloy with Cu such as Ni, for example, as a conductive component.

The multilayer ceramic capacitor 1 includes first and second

external terminal electrodes

6 and 7 formed on each end of the capacitor body 5. The first external terminal electrode 6 is electrically connected to the first capacitance forming electrode 3, and the second external terminal electrode 7 is electrically connected to the second capacitance forming electrode 4. The first capacitor forming electrodes 3 and the second capacitor forming electrodes 4 are alternately arranged in the stacking direction.

The capacitor body 5 includes a capacitance forming portion 8 in which the

capacitance forming electrodes

3 and 4 are distributed, and

outer layer portions

9 and 10 positioned so as to sandwich the capacitance forming portion 8 in the stacking direction. In this embodiment, the thickness of each dielectric ceramic layer 2 is 5 μm or less, the number of dielectric ceramic layers 2 in the capacitance forming portion 8 is 30 or more, and each of the

outer layer portions

9 and 10 is The thickness of the dielectric ceramic layer 2 is at least four times the thickness of each dielectric ceramic layer 2.

In the

outer layer portions

9 and 10,

non-effective electrodes

11 and 12 extending in parallel with the capacitance forming electrodes 3 (B) and 4 (B) located in the outermost layer are formed, respectively. The

non-effective electrodes

11 and 12 have the same area as the

capacitance forming electrodes

3 and 4 and are formed so as not to be in contact with any of the first and second

external terminal electrodes

6 and 7. The

non-effective electrodes

11 and 12 are configured to include Cu derived from Cu included in the dielectric ceramic constituting the dielectric ceramic layer 2 as a result of a firing process performed in the manufacturing process of the multilayer ceramic capacitor 1 described later. Solid solution or alloy.

Further, the

capacitance forming electrodes

3 and 4 also contain Cu derived from Cu contained in the dielectric ceramic as a result of the firing step performed in the manufacturing process of the multilayer ceramic capacitor 1. 4, the Cu concentration of the capacitance forming electrodes 3 (B) and 4 (B) located in the outermost layer is 5 of the Cu concentration of the capacitance forming electrodes 3 (C) and 4 (C) located in the center. No more than twice, preferably no more than 3 times.

As described above, the capacitance forming electrodes located in the outermost layer are indicated by “3 (B)” and “4 (B)”, and the capacitance forming electrodes located in the center are indicated by “3 (C)” and “ 4 (C) ”distinguishes it from other capacitor forming electrodes. In particular, when such distinction is not necessary, the capacitor forming electrodes are simply indicated by reference numerals“ 3 ”and“ 4 ”. Show.

In this embodiment, since the total number of the

capacitance forming electrodes

3 and 4 is 2n (n is a natural number), the nth capacitance forming electrode 3 (C) and the (n + 1) th capacitance forming electrode are located at the center. The capacitance forming electrode 4 (C) is selected, and the Cu concentration of the capacitance forming electrode located in the center is determined by the Cu concentration of the capacitance forming electrode 3 (C) and the Cu concentration of the capacitance forming electrode 4 (C). It means that it is the average value. On the other hand, when the total number of the

capacitance forming electrodes

3 and 4 is 2n + 1, the (n + 1) th capacitance forming electrode is a capacitance forming electrode located at the center.

The multilayer ceramic capacitor 1 having the above-described configuration is manufactured as follows.

FIG. 3 is a cross-sectional view showing the raw capacitor body 5 prepared to obtain the capacitor body 5 shown in FIG. The same reference numerals as those used for the elements provided in the sintered capacitor body 5 shown in FIG. 1 are used for the corresponding elements in the raw state of the capacitor body 5 shown in FIG. To do.

In order to manufacture the multilayer ceramic capacitor 1, first, a raw capacitor body 5 as shown in FIG. 3 is prepared. The raw capacitor body 5 includes a plurality of dielectric ceramic green layers 2 and a dielectric ceramic green layer 2 including a dielectric ceramic material mainly composed of BaTiO ₃ -based ceramics and Cu as a minor component. It comprises a plurality of

capacitance forming electrodes

3 and 4 formed along a specific interface.

The raw capacitor body 5 includes a capacitance forming portion 8 in which the

capacitance forming electrodes

3 and 4 are distributed and

outer layer portions

9 and 10 positioned so as to sandwich the capacitance forming portion 8 in the stacking direction.

Ineffective layers

11 and 12 are formed on the

outer layer portions

9 and 10, respectively. These

non-effective electrodes

11 and 12 include a metal that can form a solid solution or alloy with Cu, for example, a metal such as Ni, Pd, or Pt, when it is formed inside the raw capacitor body 5.

Next, the raw capacitor body 5 is fired.

Next, as shown in FIG. 1, the first and second

external terminal electrodes

6 and 6 are electrically connected to specific ones of the

capacitance forming electrodes

3 and 4 in the sintered capacitor body 5, respectively. 7 is formed on each end of the capacitor body 5. For forming the external

terminal electrodes

6 and 7, for example, a method by applying and baking a conductive paste is applied. In the step of applying the conductive paste for the external

terminal electrodes

6 and 7 on each end of the raw capacitor body 5 and firing the raw capacitor body 5, the conductive material for the external

terminal electrodes

6 and 7 is used. The adhesive paste may be baked at the same time.

In the firing step described above, Cu contained in the dielectric ceramic material tends to diffuse to the

capacitance forming electrodes

3 and 4 containing, for example, Ni as a conductive component. In particular, in the

outer layer portions

9 and 10, since the absolute amount of Cu contained in the dielectric ceramic material is large, when the

non-effective electrodes

11 and 12 are not formed, the capacitance forming electrodes 3 (B) and A large amount of Cu is absorbed in 4 (B).

However, in this embodiment, the

non-effective electrodes

11 and 12 are formed, and the

non-effective electrodes

11 and 12 include a metal that can form a solid solution or alloy with Cu as described above. Some of the Cu contained in the dielectric ceramic material at 10 and 10 is advantageously absorbed by the

non-effective electrodes

11 and 12 so as to form a solid solution or alloy with the metal. As a result, it is possible to prevent Cu from being concentrated particularly in the capacitance forming electrodes 3 (B) and 4 (B) located in the outermost layer, so that the fattening phenomenon and the smoothness are less likely to be caused. 5, it is possible to make it difficult for delamination and short-circuit defects to occur.

If the

non-effective electrodes

11 and 12 are too far away from the capacitance forming electrodes 3 (B) and 4 (B) located in the outermost layer, the capacitance forming electrodes 3 (B) and B located in the outermost layer 4 (B), the effect of preventing the concentration of Cu is reduced, and on the other hand, if it is too close, the

non-effective electrodes

11 and 12 have their capacitance phenomenon due to absorption of Cu by the capacity forming electrode 3 (B ) And 4 (B) are adversely affected, and in either case, a short circuit failure may be caused. In order to avoid such an inconvenience more reliably, as shown in FIG. 2, the

non-effective electrodes

11 and 12 and the capacitance forming electrodes 3 (B) and 4 (B) located in the outermost layer are used. Each distance D1 is 0.8 times the thickness dimension D2 of the dielectric ceramic layer 2 between the

capacitance forming electrodes

3 and 4 or 1 μm, whichever is shorter, and the thickness dimension of the dielectric ceramic layer 2 It is preferably 4 times or less of D2.

Note that the Cu concentration of the capacitance forming electrodes 3 (B) and 4 (B) located in the outermost layer is usually higher than the Cu concentration of the capacitance forming electrodes 3 (C) and 4 (C) located in the center. Get higher. However, the Cu-absorbing action by the

non-effective electrodes

11 and 12 in the firing step described above is strong, and the

non-effective electrodes

11 and 12 are capacitance forming electrodes 3 (B) and 4 (B), respectively, located in the outermost layer. In the case where the capacitor forming electrodes 3 (B) and 4 (B) located in the outermost layer are formed, the Cu concentration of the capacitor forming electrodes 3 (C) and 4 located in the center is the same. It may be lower than the Cu concentration of (C).

FIG. 4 is a diagram corresponding to FIG. 2 for explaining the second embodiment of the present invention. 4, elements corresponding to those shown in FIG. 2 are denoted by the same reference numerals, and redundant description is omitted.

The second embodiment is characterized in that a plurality of, for example, five non-effective electrodes 11 are formed in the outer layer portion 9 so as to extend in parallel with each other. Although not shown in FIG. 4, the other non-effective electrodes 12 are similarly formed in the other outer layer portion 10 so as to extend in parallel with each other. According to this embodiment, the effect | action by the

non-effective electrodes

11 and 12 can be exhibited more reliably.

FIG. 5 is a view corresponding to FIG. 1 for explaining the third embodiment of the present invention. In FIG. 5, elements corresponding to those shown in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

The multilayer ceramic capacitor 1a according to the third embodiment is characterized in that each of the

non-effective electrodes

11a and 12a is divided into a plurality of parts, for example, four parts. Each of the

non-effective electrodes

11a and 12a may be further divided into a number of parts. According to this embodiment, the total area of each of the

non-effective electrodes

11a and 12a can be made smaller than the area of each of the

non-effective electrodes

11 and 12 shown in FIG. 1, thus reducing the total area. This can be cost effective.

FIG. 6 is a view corresponding to FIG. 1 for explaining the fourth embodiment of the present invention. In FIG. 6, elements corresponding to those shown in FIG. 1 are given the same reference numerals, and redundant description is omitted.

In the multilayer ceramic capacitor 1b according to the fourth embodiment, the

ineffective electrodes

11b and 12b reach one of the end faces of the capacitor body 5 so as to be in contact with the first and second

external terminal electrodes

6 and 7, respectively. It is characterized by being formed. In the case of this embodiment, for example, compared to the case of the first embodiment, the possibility of delamination increases due to the fat phenomenon due to Cu absorption of the

ineffective electrodes

11b and 12b themselves, which is not preferable. These embodiments are also meaningful to clearly show that they are within the scope of the present invention.

Next, experimental examples carried out to confirm the effects of the present invention will be described.

[Experimental Example 1]
BaCO ₃ , CaCO ₃ , SrCO ₃ and TiO ₂ were prepared as starting materials. These raw materials are one of barium titanate-based solid solutions represented by the general formula ABO ₃ having a perovskite structure in the ceramic compositions shown in Table 1 (Ba _1-wx Ca _w Sr _x ) _k. Weighed to obtain a composition of (Ti _1-y Zr _y ) O ₃ . Thereafter, these weighed raw materials were wet-mixed with a ball mill, pulverized, dried, and calcined in air at a temperature of 950 to 1150 ° C. for 2 hours to obtain a barium titanate solid solution.

On the other hand, Cu, R (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Y) as subcomponents of the ceramic composition shown in Table 1; mg, is the oxide of Mn and _{_{_{_{Ni, CuO, La 2 O 3}}}} , CeO 2, Pr 6 O 11, Nd 2 O 3, Sm 2 O 3, Eu 2 O 3, Gd 2 O 3, Tb 4 O ₇ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ , Y ₂ O ₃ , MgO, MnO and NiO are prepared, and a sintering aid (silicon oxide is added). A colloidal silica solution containing 30% by weight in terms of SiO ₂ was prepared.

Subsequently, the barium titanate solid solution, the subcomponent oxide, and the sintering aid were weighed so that the desired ceramic compositions C1 to C51 shown in Table 1 were obtained. In Table 1, the subcomponent oxide is shown in a molar ratio with respect to 100 mole parts of the barium titanate solid solution, and the sintering aid is based on 100 parts by weight of the total of the barium titanate solid solution and the subcomponent oxide. It is shown in weight ratio.

Next, a barium titanate solid solution, subcomponent oxides and sintering aids weighed so as to obtain ceramic compositions C1 to C51 shown in Table 1 were added to an organic solvent such as a polyvinyl butyral binder and ethanol. And wet mixed by a ball mill to prepare a slurry. This slurry was formed into a sheet by a doctor blade method to obtain a rectangular dielectric ceramic green sheet.

Next, a conductive paste containing Ni as a conductive component was printed on the green sheet to form a conductive paste layer serving as a capacitance forming electrode. Also, a conductive paste containing Ni as a conductive component was printed on another green sheet to form a conductive paste layer serving as an ineffective electrode having the same area as the capacitance forming electrode.

Thereafter, the green sheets on which the conductive paste layer to be the capacitance forming electrode is formed are stacked so that the side from which the conductive paste layer is drawn is alternated, and the conductive sheet to be the capacitance forming electrode in the capacitance forming portion. A green capacitor body was obtained by laminating 100 sheets of conductive paste layers and laminating one sheet of green sheet on which conductive paste layers serving as ineffective electrodes were formed on both outer layer portions. Here, after sintering, each thickness of the dielectric ceramic layer in the capacitance forming portion is 2 μm, and for the ineffective electrode, the distance D1 (see FIG. 2) from the capacitance forming electrode located in the outermost layer is 1 μm. It was made to form at a position.

Next, the raw capacitor body was heated to a temperature of 350 ° C. in an N ₂ atmosphere to remove the binder, and then H ₂ —N ₂ —H ₂ with an oxygen partial pressure of 10 ⁻⁹ to 10 ⁻¹² MPa. In a reducing atmosphere composed of O gas, firing was performed in a temperature range of 1000 to 1400 ° C. for 2 hours to obtain a sintered capacitor body. In addition, about the said baking temperature, the capacitor | condenser main body after sintering produced using each ceramic composition was cross-sectional-polished, and the porosity of the outer layer was set to the temperature used as 3% or less.

Thereafter, an Ag paste containing a glass frit of B ₂ O ₃ —Li ₂ O—SiO ₂ —BaO system was applied to both end faces of the obtained capacitor body, and baked at a temperature of 600 ° C. in an N ₂ atmosphere. An external terminal electrode electrically connected to the capacitance forming electrode was formed.

Next, a nickel plating solution was prepared, and nickel plating was performed on the Ag external terminal electrode by a barrel plating method. Finally, a solder plating solution was prepared, and this nickel plating film was solder plated by a barrel plating method to obtain a multilayer ceramic capacitor as a sample. The multilayer ceramic capacitor according to each sample has a structure as shown in FIG. 1, has a lengthwise dimension of 3.2 mm, a widthwise dimension of 1.6 mm, and a thicknesswise dimension of 1.6 mm. The overlapping area of the capacitance forming electrodes per layer was 3.3 mm ² .

As shown in Table 2, the multilayer ceramic capacitor according to each sample produced in this way was evaluated for each item of “short defect rate”, “delamination”, and “WDX strength”. These items were evaluated as follows.

“Short-circuit defect rate”: 100 samples were taken out of the multilayer ceramic capacitors according to each sample, whether or not a short-circuit defect occurred was evaluated, and the ratio of the number of short-circuit defects in 100 was determined.

"Delamination": 50 capacitors are extracted from the multilayer ceramic capacitors of each sample, and the surface defined by the length and thickness dimensions is mirror-polished, and then the capacitance is formed on the outermost layer with an optical microscope. The presence / absence of delamination in the entire electrode was confirmed, and the ratio of the number of delamination out of 50 was determined.

“WDX strength”: the surface defined by the length-direction dimension and the thickness-direction dimension of the multilayer ceramic capacitor according to each sample is mirror-polished, and a capacitance-forming electrode located at the outermost layer and a capacitance-forming electrode located at the center WDX point analysis was performed. If the Cu concentration (specified by the Cu / Ni intensity ratio) of the capacitance forming electrode located in the outermost layer is 5 times or less than the Cu concentration of the capacitance forming electrode located in the center, it is determined that it is good. Then, “G” is displayed. In Tables 4 and 5 to be described later, there are samples indicated as “NG”, but these are those of the capacitor forming electrode located at the center of the Cu concentration of the capacitor forming electrode located in the outermost layer. This is a case where the Cu concentration exceeds 5 times.

The “ceramic composition” in Table 2 corresponds to the “ceramic composition symbol” shown in Table 1, and indicates the composition of the dielectric ceramic applied in each sample shown in Table 2.

From Table 2, Cu contained in the outer layer portion is dissolved in the ineffective electrode, so that the solid solution of Cu in the capacitor forming electrode is suppressed, and as a result, the Cu concentration of the capacitor forming electrode located in the outermost layer is reduced. Can be made uniform to 5 times or less of the Cu concentration of the capacitance forming electrode located in the center. Thus, by preventing the concentration of Cu in the capacitance forming electrode, delamination and short-circuit failure due to the thickness of the capacitance forming electrode and a decrease in smoothness could be suppressed.

[Experiment 2]
Experimental Example 2 was carried out in order to confirm that the effect of the present invention was achieved even when the metal that can form a solid solution or alloy with Cu contained in the ineffective electrode was changed.

Each of the metals contained in the ineffective electrode was changed from Ni to Pd or Pt as shown in the column of “Ineffective electrode metal” in Table 3, by the same method as in Experimental Example 1, A multilayer ceramic capacitor according to the sample was produced and evaluated. The evaluation results are shown in Table 3. As for the dielectric ceramic, only those having the “ceramic composition symbol” shown in the “ceramic composition” column of Table 3 among the ceramic compositions shown in Table 1 were applied.

As can be seen from Table 3, even if the metal contained in the non-effective electrode was changed, the same effect as in Experimental Example 1 was obtained.

[Experiment 3]
Experimental example 3 is a case where the design such as the distance D1 from the capacitance forming electrode to the ineffective electrode located in the outermost layer as shown in FIG. 2 and the thickness D2 of the dielectric ceramic layer between the capacitance forming electrodes is changed. This was carried out in order to investigate the influence on the effect of the present invention.

(1) to (5) shown in the column “implementation pattern” in Table 4 indicate the following designs.
(1) The thickness of the dielectric ceramic layer was 5 μm, and the distance from the capacitance forming electrode located in the outermost layer to the ineffective electrode was 1 μm.
(2) The thickness of the dielectric ceramic layer was 2 μm, and the distance from the capacitance forming electrode located on the outermost layer to the ineffective electrode was 8 μm (= thickness of the dielectric ceramic layer × 4).
(3) The thickness of the dielectric ceramic layer was 2 μm, and the distance from the capacitance forming electrode located on the outermost layer to the ineffective electrode was 10 μm (= thickness of the dielectric ceramic layer × 5).
(4) The thickness of the dielectric ceramic layer was 0.8 μm, and the distance from the capacitance forming electrode located in the outermost layer to the ineffective electrode was 1 μm.
(5) The thickness of the dielectric ceramic layer was 0.8 μm, and the distance from the capacitance forming electrode located in the outermost layer to the ineffective electrode was 0.6 μm.

A multilayer ceramic capacitor according to each sample was produced by the same method as in Experimental Example 1 except that the design of the multilayer ceramic capacitor was changed as shown in the column “Execution pattern” in Table 4. Evaluation was performed. The evaluation results are shown in Table 4. For the dielectric ceramic, only those having the “ceramic composition symbol” shown in the “ceramic composition” column of Table 4 among the ceramic compositions shown in Table 1 were applied.

As can be seen from Table 4, even when the design such as the distance from the capacitance forming electrode located at the outermost layer to the ineffective electrode and the thickness of the dielectric ceramic layer between the capacitance forming electrodes is changed, the experimental example The same effect as in the case of 1 was obtained.

However, the “effective pattern” is too far from the capacitance forming electrode located in the outermost layer as in the case of (3), or the ineffective electrode is in the outermost layer as in (5). If the electrode is too close to the capacitor forming electrode located in the region, a short circuit failure may occur due to the ineffective electrode and / or the capacitor forming electrode becoming fat.

[Experimental Example 4]
Experimental Example 4 was carried out in order to investigate the influence on the effect of the present invention when the number of stacked capacitance forming electrodes was changed. In Experimental Example 4, a sample without an ineffective electrode was also evaluated.

A multilayer ceramic capacitor according to each sample was manufactured by the same method as in Experimental Example 1 except that the number of stacked capacitance forming electrodes was changed as shown in the column “Number of stacked layers” in Table 5. . An increase in the “number of layers” means that the outer layer becomes thinner accordingly. Note that the sample with “100” is the same as the corresponding sample in Experimental Example 1. Samples 350 to 356 in Table 5 are comparative samples without ineffective electrodes. As for the dielectric ceramic, only those having the “ceramic composition symbol” shown in the “ceramic composition” column of Table 5 among the ceramic compositions shown in Table 1 were applied.

Then, the multilayer ceramic capacitor according to each sample was evaluated by the same method as in Experimental Example 1. The evaluation results are shown in Table 5.

As can be seen from Table 5, basically, the same effect as in Experimental Example 1 was obtained even when the number of stacked layers for forming the capacitance was changed.

In addition, since the total amount of Cu in the outer layer portion decreases as the outer layer portion becomes thinner, it is expected that the Cu solid solution in the capacitance forming electrode located in the outermost layer is reduced and defects are less likely to occur. However, as can be seen from a comparison between samples 350 to 356 having no ineffective electrode, when the number of stacked layers increases and the outer layer portion becomes thinner, the binding by the outer layer portion becomes weaker and delamination tends to occur. From this, the present invention is more effectively applied as the number of laminated layers of the capacity forming electrode is larger than the number of laminated layers, such as 10 layers, and the outer layer portion is thinner. I can say that.

[Experimental Example 5]
Experimental Example 5 was carried out in order to investigate the influence on the effect of the present invention when the shape or arrangement of the ineffective electrode was changed.

A to C shown in the “execution pattern” column of Table 6 indicate the following designs, respectively.
A. As shown in FIG. 4, five non-effective electrodes were laminated on both outer layer portions. The interval between the non-effective electrodes was 1 μm.
B. As shown in FIG. 5, the non-effective electrode was divided into four parts each having an area of 0.8 mm ² .
C. As shown in FIG. 6, the non-effective electrode was formed so that one end edge reached the end face of the capacitor body.

A multilayer ceramic capacitor according to each sample was prepared by the same method as in Experimental Example 1, except that the design of the multilayer ceramic capacitor was changed as shown in the column “Execution pattern” in Table 6. Evaluation was performed. The evaluation results are shown in Table 6. As for the dielectric ceramic, only those having the “ceramic composition symbol” shown in the “ceramic composition” column of Table 6 among the ceramic compositions shown in Table 1 were applied.

As can be seen from Table 6, even when the shape and arrangement of the non-effective electrodes were changed, basically the same effects as those in Experimental Example 1 were obtained.

However, if the one end edge of the ineffective electrode reaches the end face of the capacitor body as in the case where the “implementation pattern” is C, the Cu content is the same as in the case where the “ceramic composition” is C12 or C34. When a dielectric ceramic exceeding 2 mole parts is applied, delamination may occur. From this, it can be seen that the Cu content is desirably 2 mol parts or less.

Claims

A plurality of laminated dielectric ceramic layers comprising a dielectric ceramic containing a BaTiO 3 ceramic as a main component and Cu as a subcomponent; and a metal capable of forming a solid solution or an alloy with Cu, and between the dielectric ceramic layers A capacitor body composed of a plurality of capacitance forming electrodes formed along a specific interface;
First and second external terminal electrodes formed on the outer surface of the capacitor body so as to be electrically connected to specific ones of the capacitance forming electrodes,
The capacitor forming electrode further includes Cu derived from the Cu contained in the dielectric ceramic, and the Cu concentration of the capacitor forming electrode located in the outermost layer among the plurality of capacitor forming electrodes is at the center. It is 5 times or less of the Cu concentration of the capacitance forming electrode located.
Multilayer ceramic capacitor.
A plurality of laminated dielectric ceramic layers comprising a dielectric ceramic containing a BaTiO 3 ceramic as a main component and Cu as a subcomponent; and a metal capable of forming a solid solution or an alloy with Cu, and between the dielectric ceramic layers A capacitor body composed of a plurality of capacitance forming electrodes formed along a specific interface;
First and second external terminal electrodes formed on the outer surface of the capacitor body so as to be electrically connected to specific ones of the capacitance forming electrodes,
The capacitor body includes a capacitance forming portion in which the capacitance forming electrodes are distributed and an outer layer portion positioned so as to sandwich the capacitance forming portion in the stacking direction.
In the outer layer portion, an ineffective electrode including a solid solution or an alloy extending in parallel with the capacitance forming electrode located in the outermost layer and including Cu derived from Cu contained in the dielectric ceramic is formed. Being
Multilayer ceramic capacitor.
The distance between the non-effective electrode and the capacitor forming electrode located on the outermost layer is not less than 0.8 times the thickness of the dielectric ceramic layer between the capacitor forming electrodes or 1 μm, whichever is shorter The multilayer ceramic capacitor according to claim 2, wherein the thickness is 4 times or less the thickness dimension of the dielectric ceramic layer between the capacitance forming electrodes.
The multilayer ceramic capacitor according to claim 2, wherein the non-effective electrode is formed so as not to be in contact with any of the first and second external terminal electrodes.
The multilayer ceramic capacitor according to claim 1 or 2, wherein the Cu content of the dielectric ceramic is 0.1 to 2 mole parts, based on 100 mole parts of BaTiO 3 ceramic as a main component.
The multilayer ceramic capacitor according to claim 1 or 2, wherein the metal capable of forming a solid solution or alloy with Cu includes Ni.
A dielectric ceramic material comprising a plurality of laminated dielectric ceramic green layers including a dielectric ceramic material mainly composed of BaTiO 3 -based ceramics and Cu as a minor component, and a metal capable of forming a solid solution or alloy with Cu A plurality of capacitance forming electrodes formed along a specific interface between the green layers, and a capacitance forming portion in which the capacitance forming electrodes are distributed and an outer layer portion positioned so as to sandwich the capacitance forming portion in the stacking direction A raw capacitor body having a non-effective electrode formed on the outer layer portion, which is formed in parallel with the capacitance forming electrode located in the outermost layer and includes a metal capable of forming a solid solution or alloy with Cu. A process to prepare;
Firing the raw capacitor body;
Forming first and second external terminal electrodes on the outer surface of the capacitor body so as to be electrically connected to specific ones of the capacitance forming electrodes, respectively.
The firing step includes a step of absorbing a part of the Cu contained in the dielectric ceramic material in the outer layer portion by the ineffective electrode so as to make the solid solution or alloy with the metal. ,
Manufacturing method of multilayer ceramic capacitor.