KR102491421B1 - Multilayer ceramic capacitor and manufacturing method of multilayer ceramic capacitor - Google Patents

Abstract

A multilayer ceramic capacitor capable of suppressing a decrease in the continuity rate of an internal electrode layer and a manufacturing method thereof are provided.
A multilayer ceramic capacitor has a laminated structure in which dielectric layers containing ceramic as a main component and internal electrode layers containing metal as a main component are alternately laminated, and particles containing ceramic as a main component are present in the internal electrode layers. It is characterized in that, in a cross section of the internal electrode layer in the stacking direction of the dielectric layer and the internal electrode layer, an area ratio in which the particles are present is 10% or more.

Description

Multilayer ceramic capacitor and manufacturing method thereof

The present invention relates to a multilayer ceramic capacitor and a manufacturing method thereof.

DESCRIPTION OF RELATED ART In recent years, with the miniaturization of electronic devices, such as a smart phone and a mobile phone, the miniaturization of the electronic component mounted is progressing rapidly. For example, in multilayer ceramic capacitors, thinning of dielectric layers and internal electrode layers is required in order to reduce chip size while securing predetermined characteristics.

However, when the sintering temperatures of the metal of the internal electrode layer and the ceramic of the dielectric layer are different, there is a problem that the continuity rate of the internal electrode layer after sintering is lowered. If the internal electrode layer is thinned, there is a concern that the continuity rate of the layer will further decrease. Therefore, it is known to add a ceramic common material to the internal electrode layer in order to bring about a shrinkage delay effect (see Patent Document 1, for example).

Japanese Unexamined Patent Publication No. 2014-082435

However, since the common material tends to diffuse into the dielectric layer during the sintering process, it is difficult to sufficiently suppress the decrease in the continuity rate of the internal electrode layer.

The present invention has been made in light of the above problems, and an object of the present invention is to provide a multilayer ceramic capacitor capable of suppressing a decrease in the continuity rate of internal electrode layers and a method for manufacturing the same.

A multilayer ceramic capacitor according to the present invention has a laminated structure in which dielectric layers containing ceramic as a main component and internal electrode layers containing metal as a main component are alternately laminated, and the internal electrode layers contain particles containing ceramic as a main component. present, and in a cross section of the internal electrode layer in the stacking direction of the dielectric layer and the internal electrode layer, an area ratio in which the particles exist is 10% or more.

In the above multilayer ceramic capacitor, the main component metal of the internal electrode layer may be nickel.

In the above multilayer ceramic capacitor, the main component ceramic of the particles may be barium titanate.

In the above multilayer ceramic capacitor, the main component ceramic of the dielectric layer may be barium titanate.

In the multilayer ceramic capacitor, the area ratio may be obtained from the total area of 10 internal electrode layers arbitrarily selected using SEM images of cross sections of internal electrode layers and the total area of the particles in the 10 internal electrode layers. do.

A method for manufacturing a multilayer ceramic capacitor according to the present invention contains, as a main component, metal powder having an average particle size of 100 nm or less and a standard deviation of particle size distribution of 1.5 or less on a green sheet containing ceramic powder, and an average particle size of 10 nm. A first step of arranging a pattern of a metal conductive paste containing, as a common material, a ceramic powder having a standard deviation of 5 or less and a standard deviation of particle size distribution of 5 or less, and firing a ceramic laminate obtained by laminating a plurality of laminated units obtained in the first step. and a second step of forming an internal electrode layer by sintering the metal powder and forming a dielectric layer by sintering ceramic powder of the green sheet, wherein the internal electrode layer and the dielectric layer are stacked in a stacking direction. It is characterized in that, in the cross section of, the area ratio in which particles containing ceramic as a main component are present is 10% or more.

In the method for manufacturing the multilayer ceramic capacitor, in the second step, the average heating rate from room temperature to the maximum temperature may be 30°C/minute or more and 80°C/minute or less.

In the method for manufacturing the multilayer ceramic capacitor, the metal powder may contain nickel as a main component.

In the manufacturing method of the multilayer ceramic capacitor, the common material may be barium titanate as a main component.

In the method for manufacturing the multilayer ceramic capacitor, the ceramic powder of the green sheet may contain barium titanate as a main component.

In the manufacturing method of the multilayer ceramic capacitor, the area ratio is the ratio of the total area of the 10 internal electrode layers arbitrarily selected using SEM images of cross sections of the internal electrode layers to the total area of the particles in the 10 internal electrode layers. It can be obtained from area.

According to the present invention, it is possible to provide a multilayer ceramic capacitor capable of suppressing a decrease in the continuity rate of internal electrode layers and a method for manufacturing the same.

1 is a partial cross-sectional perspective view of a multilayer ceramic capacitor.
2 is a diagram showing a continuity rate.
3(a) is a diagram illustrating an internal electrode layer when the crystal grain size is large, and (b) is a diagram illustrating an internal electrode layer when the crystal grain size is small.
4 is a diagram illustrating a flow of a method for manufacturing a multilayer ceramic capacitor.
5(a) is a diagram showing the particle size distribution of the main component metal of the conductive paste for forming internal electrodes in Examples and Comparative Examples, and (b) is a diagram showing the conductive paste for forming internal electrodes in Examples and Comparative Examples. It is a figure showing the particle size distribution of common materials in the paste.
6(a) and (b) are SEM images of cross sections of dielectric layers and internal electrode layers in the stacking direction, and (c) is a diagram showing area ratios of particles mainly composed of ceramics.
7 is a diagram showing the results of Examples and Comparative Examples.
8 is a graph showing the evaluation results of permittivity.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment is described, referring drawings.

(Embodiment)

1 is a partial cross-sectional perspective view of a multilayer ceramic capacitor 100 according to an embodiment. As illustrated in FIG. 1 , the multilayer ceramic capacitor 100 includes a multilayer chip 10 having a rectangular parallelepiped shape, and external electrodes 20a and 20b provided on two opposite end surfaces of the multilayer chip 10. do. Also, of the four surfaces other than the two end surfaces of the stacked chip 10, two surfaces other than the upper and lower surfaces in the stacking direction are referred to as side surfaces. The external electrodes 20a and 20b extend to the top, bottom and two side surfaces of the stacked chip 10 in the stacking direction. However, the external electrodes 20a and 20b are separated from each other.

The multilayer chip 10 has a structure in which a dielectric layer 11 containing a ceramic material serving as a dielectric as a main component and an internal electrode layer 12 containing a metal material such as a non-metallic material as a main component are alternately laminated. The edge of each internal electrode layer 12 is alternately exposed to the end face of the multilayer chip 10 on which the external electrodes 20a are installed and the end face on which the external electrodes 20b are installed. As a result, each internal electrode layer 12 alternately conducts the external electrode 20a and the external electrode 20b. As a result, the multilayer ceramic capacitor 100 has a structure in which a plurality of dielectric layers 11 are stacked with internal electrode layers 12 interposed therebetween. Further, in the laminate of the dielectric layer 11 and the internal electrode layer 12, the internal electrode layer 12 is disposed on the outermost layer in the stacking direction, and the upper and lower surfaces of the laminate are covered with a cover layer 13. there is. The cover layer 13 has a ceramic material as its main component. For example, the material of the cover layer 13 has the same main component as that of the dielectric layer 11 and ceramic material.

The size of the multilayer ceramic capacitor 100 is, for example, 0.2 mm in length, 0.125 mm in width, and 0.125 mm in height, or 0.4 mm in length, 0.2 mm in width, 0.2 mm in height, or 0.6 mm in length, 0.3 mm in width, and 0.3 mm in height. mm, or 1.0 mm long, 0.5 mm wide, 0.5 mm high, or 3.2 mm long, 1.6 mm wide, 1.6 mm high, or 4.5 mm long, 3.2 mm wide, and 2.5 mm high, but limited to these sizes It is not.

The internal electrode layer 12 has a non-metal such as Ni (nickel), Cu (copper), or Sn (tin) as a main component. As the internal electrode layer 12, a noble metal such as Pt (platinum), Pd (palladium), Ag (silver), Au (gold) or an alloy containing these may be used as a main component. The thickness of the internal electrode layer 12 is, for example, 0.5 μm or less, and preferably 0.3 μm or less. The dielectric layer 11 has, for example, a ceramic material having a perovskite structure represented by the general formula ABO ₃ as a main component. In addition, the perovskite structure includes ABO _{3 -α} having a non-stoichiometric composition. For example, as the ceramic material, BaTiO ₃ (barium titanate), CaZrO ₃ (calcium zirconate), CaTiO ₃ (calcium titanate), SrTiO ₃ (strontium titanate), Ba forming a perovskite structure _{1 -x- y} Ca _x Sr _y Ti _{1 - z} Zr _z O ₃ (0≤x≤1, 0≤y≤1, 0≤z≤1) and the like can be used.

In order to increase the size and capacity of the multilayer ceramic capacitor 100, thinning of the dielectric layer 11 and the internal electrode layer 12 is required. However, if the thickness of the internal electrode layer 12 is attempted, it becomes difficult to maintain a high continuity rate. This is because of the following reasons. When the internal electrode layer 12 is obtained by sintering metal powder, it is spheroidized to minimize surface energy when sintering proceeds. Since the sintering of the metal component of the internal electrode layer 12 proceeds more easily than the main component ceramic of the dielectric layer 11, if the temperature is raised until the main component ceramic of the dielectric layer 11 is sintered, the metal component of the internal electrode layer 12 becomes oversintered and tends to be spheroidized. In this case, if there is an opportunity (defect) to break, the internal electrode layer 12 breaks starting from the defect, and the continuity rate decreases. If the thickness of the dielectric layer 11 and the internal electrode layer 12 progresses, the continuity rate may further decrease.

Therefore, it is conceivable to delay shrinkage of the internal electrode layer 12 by adding a common material containing ceramic as a main component to the internal electrode layer 12 . However, if the common material is discharged to the dielectric layer 11 side by diffusion in the sintering process, it is difficult to suppress the decrease in continuity rate. In addition, as the common material is absorbed into the dielectric layer 11, the A/B ratio (ratio of A site and B site of perovskite) of the material in the dielectric layer 11, the difference in composition, and the dielectric constant ε are different from the design value. value, there is a risk that the target capacity value cannot be obtained.

2 is a diagram showing a continuity rate. As illustrated in FIG. 2 , in an observation area having a length L0 in a certain internal electrode layer 12, the lengths L1, L2, ..., Ln of the metal portion are measured and summed, and the ratio of the metal portion is ΣLn/L0 can be defined as the continuity rate of that layer.

Therefore, in this embodiment, the crystal grain size of the internal electrode layer 12 is reduced. Fig. 3(a) is a diagram illustrating the internal electrode layer 12 when the crystal grain size is large. Fig. 3(b) is a diagram illustrating the internal electrode layer 12 when the crystal grain size is small. As exemplified in FIGS. 3(a) and 3(b) , when the crystal grains 14 become smaller, common materials tend to remain in the internal electrode layer 12 . For example, as the crystal grains 14 become smaller, the number of grain boundaries 16 increases, and co-materials remain in the crystal grain boundaries 16, so that particles containing ceramic as a main component in the entire internal electrode layer 12 (15) is thought to exist in abundance. Specifically, in the cross section of the internal electrode layer 12 in the stacking direction of the dielectric layer 11 and the internal electrode layer 12, the area ratio in which the particles 15 exist is set to 10% or more. For example, the cross section is a cross section in a plane formed by the stacking direction of the dielectric layer 11 and the internal electrode layer 12 and the opposite direction of the external electrode 20a and the external electrode 20b. In this configuration, the remaining amount of common materials increases. As a result, oversintering of the metal components of the internal electrode layer 12 during sintering is suppressed, and breakage of the internal electrode layer 12 is suppressed. As a result, a decrease in the continuity rate of the internal electrode layer 12 can be suppressed. In addition, the diffusion of common materials into the dielectric layer 11 is suppressed, and the difference in A/B ratio or composition of the materials in the dielectric layer 11 and the decrease in the dielectric constant ε are suppressed, so that desired dielectric properties can be secured. As a result, deterioration of bias characteristics is suppressed, and high capacity is obtained. Moreover, it is preferable to set it as 12 % or more, and, as for the said area ratio, it is more preferable to set it as 14 % or more. In addition, the above area ratio is the total area of the 10 internal electrode layers 12 arbitrarily selected using cross-sectional SEM images of the internal electrode layers 12, for example, and the internal electrode layers 12 of the 10 layers. It can be obtained from the total area of the particles 15 containing ceramic as a main component. Although there is a possibility that the area ratio may fluctuate in the two different internal electrode layers 12 due to manufacturing errors, etc., by calculating the area ratio using arbitrarily selected 10 internal electrode layers 12, the variation can be prevented. can be suppressed You may calculate such an area using image analysis software.

In addition, when the common material sufficiently exists in the internal electrode layer 12 without being diffused into the dielectric layer 11, the common material is collected in the internal electrode layer 12. More specifically, it is considered that the common material in the vicinity of the central portion of the internal electrode layer 12 collects the surrounding common material and grows into grains. As a result, it remains in the central portion of the internal electrode layer 12 in the thickness direction. In this case, in the thickness direction of the internal electrode layer 12, no particles 15 are present in 5% of the upper and lower portions. Therefore, in the thickness direction of the internal electrode layer 12, it is preferable that the particles 15 not exist in an area of 5% above and below each.

Next, a method for manufacturing the multilayer ceramic capacitor 100 will be described. FIG. 4 is a diagram illustrating a flow of a manufacturing method of the multilayer ceramic capacitor 100. As shown in FIG.

(raw material powder manufacturing process)

First, as illustrated in FIG. 4 , a dielectric material for forming the dielectric layer 11 is prepared. A-site elements and B-site elements included in the dielectric layer 11 are usually included in the dielectric layer 11 in the form of a sintered body of ABO ₃ particles. For example, BaTiO ₃ is a tetragonal compound having a perovskite structure and exhibits a high permittivity. This BaTiO ₃ can generally be obtained by reacting a titanium raw material such as titanium dioxide with a barium raw material such as barium carbonate to synthesize barium titanate. As a method for synthesizing the ceramic constituting the dielectric layer 11, various methods have been known in the past, and for example, a solid phase method, a sol-gel method, a hydrothermal method, and the like are known. In this embodiment, all of these can be employed.

To the obtained ceramic powder, a predetermined additive compound is added according to the purpose. As the additive compound, Mn (manganese), V (vanadium), Cr (chromium), rare earth elements (Y (yttrium), Dy (dysprosium), Tm (thulium), Ho (holmium), Tb (terbium), Yb (ytterbium) ), oxides of Sm (samarium), Eu (europium), Gd (gadolinium), and Er (erbium), and Co (cobalt), Ni (nickel), Li (lithium), B (boron), Na (sodium) ), oxides or glass of K (potassium) and Si (silicon).

In this embodiment, preferably, first, a compound containing an additive compound is mixed with ceramic particles constituting the dielectric layer 11, and calcining is performed at 820 to 1150°C. Subsequently, the obtained ceramic particles are wet-mixed together with an additive compound, dried and pulverized to prepare ceramic powder. For example, the average particle diameter of the ceramic powder is preferably 50 to 300 nm from the viewpoint of thinning the dielectric layer 11 . For example, the particle size of the ceramic powder obtained as described above may be adjusted by pulverizing as necessary, or by combining with a classification treatment to adjust the particle size.

(lamination process)

Next, to the obtained dielectric material, a binder such as polyvinyl butyral (PVB) resin, an organic solvent such as ethanol or toluene, and a plasticizer such as dioctyl phthalate (DOP) are added and wet mixed. Using the obtained slurry, for example, a strip-shaped dielectric green sheet having a thickness of 0.8 µm or less is coated on a substrate by, for example, a die coater method or a doctor blade method, and dried.

Next, a metal conductive paste for forming internal electrodes containing an organic binder is printed on the surface of the dielectric green sheet by screen printing, gravure printing, etc., thereby forming internal electrode layer patterns alternately drawn out to a pair of external electrodes having different polarities. place For the metal material of the metal conductive paste, for example, one having an average particle diameter of 100 nm or less is used. In addition, the standard deviation of the particle size is 15 or less. In this way, a sharp particle size distribution is obtained. It is preferable that it is 100 nm or less, and, as for average particle diameter, it is more preferable that it is 70 nm or less. It is preferable that it is 15 or less, and, as for the standard deviation of a particle size, it is more preferable that it is 12 or less. Moreover, it is preferable that the gradient of a cumulative particle size distribution is 8 or more. In addition, the slope of the cumulative particle size distribution can be defined as the slope (= 1/(logD80-logD20)) between D20 and D80 by plotting the cumulative particle size distribution as a logarithm.

In addition, ceramic particles are added to the metal conductive paste as a common material. The main component ceramic of the ceramic particles is not particularly limited, but is preferably the same as the main component ceramic of the dielectric layer 11. For example, barium titanate may be uniformly dispersed. As a common material, what has an average particle diameter of 10 nm or less is used, for example. In addition, the standard deviation of the particle size is set to 5 or less. In this way, a sharp particle size distribution is obtained. It is preferable that it is 15 nm or less, and, as for average particle diameter, it is more preferable that it is 10 nm or less. It is preferable that it is 5 or less, and, as for the standard deviation of a particle size, it is more preferable that it is 3 or less. Moreover, it is preferable that the gradient of a cumulative particle size distribution is 7 or more. In addition, the slope of the cumulative particle size distribution can be defined as the slope (= 1/(logD80-logD20)) between D20 and D80 by plotting the cumulative particle size distribution logarithmically.

Thereafter, the dielectric green sheet on which the internal electrode layer pattern is printed is punched to a predetermined size, and the punched dielectric green sheet is further internally separated from the substrate so that the internal electrode layer 12 and the dielectric layer 11 are alternately A predetermined number of layers (for example, 100 to 500 layers) are stacked. The cover sheet to be the cover layer 13 is pressed on and under the stacked dielectric green sheets, cut into a predetermined chip size (eg 1.0 mm x 0.5 mm), and then the base of the external electrodes 20a and 20b. A metal conductive paste serving as a layer is applied to both end faces of the cut laminate by a dipping method or the like, and then dried. As a result, a molded body of the multilayer ceramic capacitor 100 is obtained.

(firing process)

The molded body obtained in this way is subjected to binder removal treatment in a N ₂ atmosphere at 250 to 500 ° C., and then baked at 1100 to 1300 ° C. for 10 minutes to 2 hours in a reducing atmosphere with an oxygen partial pressure of 10 ⁻⁵ to 10 ⁻⁸ atm. The compound is sintered and grain grows. In this way, the multilayer ceramic capacitor 100 is obtained. In addition, by adjusting the firing conditions, the remaining amount of the common material remaining in the internal electrode layer 12 can be adjusted. Specifically, since the main component metal is sintered before the common material is ejected from the metal conductive paste by increasing the heating rate in the firing step, the common material easily remains in the internal electrode layer 12 . For example, from the viewpoint of increasing the residual amount of the common material in the internal electrode layer 12, the average temperature increase rate from room temperature to the maximum temperature in the firing step is preferably 30°C/min or more, and 45°C /min or more is more preferable. Also, if the average temperature rise rate is too high, organic components remaining in the molded body may not be sufficiently discharged, causing problems such as cracking during the firing process. Alternatively, there is a possibility that problems such as insufficient densification due to internal and external differences in sintering of the molded body and a decrease in capacitance may occur. Then, it is preferable to make an average temperature increase rate into 80 degrees C/min or less, and it is more preferable to make it 65 degrees C/min or less.

(Re-oxidation treatment process)

Thereafter, a reoxidation treatment may be performed at 600°C to 1000°C in an N ₂ gas atmosphere.

(Plating treatment process)

Thereafter, a metal coating of Cu, Ni, Sn, or the like is applied to the base layer of the external electrodes 20a and 20b by a plating process.

According to the manufacturing method of the multilayer ceramic capacitor according to the present embodiment, a highly dispersed metal conductive paste is produced by using a small-diameter material having a sharp particle size distribution as the main component metal and co-material constituting the internal electrode layer 12. Also, the incorporation of partially large materials is suppressed. By using such a metal conductive paste, diffusion of the common material into the dielectric layer 11 is suppressed during the sintering process, so that the common material remains in the internal electrode layer 12 . Specifically, in the cross section of the internal electrode layer 12 in the stacking direction of the dielectric layer 11 and the internal electrode layer 12, the area ratio in which the particles 15 containing ceramic as a main component are present is set to 10% or more. do.

If the common material remains in the internal electrode layer 12, oversintering of the metal component of the internal electrode layer 12 during sintering is suppressed, and the internal electrode layer 12 is prevented from breaking. As a result, a decrease in the continuity rate of the internal electrode layer 12 can be suppressed. In addition, the diffusion of the common material into the dielectric layer 11 is suppressed, and the decrease in the dielectric constant ε of the dielectric layer 11 is suppressed, so that desired dielectric characteristics can be secured. Moreover, it is preferable to set it as 12 % or more, and, as for the said area ratio, it is more preferable to set it as 14 % or more. In the thickness direction of the internal electrode layer 12, it is preferable that no particles 15 containing ceramics as a main component exist in an area of 5% above and below each.

[Example]

Hereinafter, multilayer ceramic capacitors according to the embodiments were fabricated, and characteristics were investigated.

(Examples 1 to 5)

Required additives were added to barium titanate powder having an average particle diameter of 100 nm (specific surface area 10 m 2 /g), and wet mixing and grinding were sufficiently performed by a ball mill to obtain a dielectric material. A dielectric green sheet was prepared by adding an organic binder and a solvent to a dielectric material by a doctor blade method. The coating thickness of the dielectric green sheet was set to 0.8 μm, polyvinyl butyral (PVB) or the like was used as an organic binder, and ethanol, toluic acid or the like was added as a solvent. In addition, a plasticizer and the like were added.

Next, the main component metal (Ni) powder of the internal electrode layer 12 (50 wt% in terms of Ni solid content), 10 parts of a common material (barium titanate), 5 parts of a binder (ethyl cellulose), a solvent, Conductive paste for forming internal electrodes containing other auxiliary agents as needed was produced by a planetary ball mill. As shown in Table 1, as the main component metal powder, those having an average particle diameter of 70 nm (specific surface area 10 m 2 /g), a standard deviation of particle diameter of 12, and a slope of cumulative particle size distribution of 8 were used. As the common material, one having an average particle diameter of 8.6 nm (specific surface area 110 m 2 /g), a standard deviation of particle diameter of 2.7, and a gradient of cumulative particle size distribution of 7 was used.

A conductive paste for forming internal electrodes was screen-printed on the dielectric sheet. 250 sheets printed with conductive paste for forming internal electrodes were overlapped, and cover sheets were laminated on top and bottom of each sheet. Thereafter, a ceramic laminate was obtained by thermal compression bonding and cut into a predetermined shape.

After the obtained ceramic laminate is de-bindered in an N ₂ atmosphere, a metal paste containing a metal filler containing Ni as a main component, a common material, a binder, a solvent, etc. is applied from both end faces to each side surface of the ceramic laminate, dried. Thereafter, the metal paste was fired simultaneously with the ceramic laminate at 1100° C. to 1300° C. for 10 minutes to 2 hours in a reducing atmosphere to obtain a sintered body. The average heating rate from room temperature to the maximum temperature was 30°C/min in Example 1, 45°C/min in Example 2, 55°C/min in Example 3, and 65°C/min in Example 4. /min, and in Example 5, it was set to 80°C/min.

The shape dimensions of the obtained sintered body were 0.6 mm in length, 0.3 mm in width, and 0.3 mm in height. The sintered body was subjected to reoxidation treatment under N ₂ atmosphere at 800° C., and then plating was performed to form a Cu plating layer, a Ni plating layer, and a Sn plating layer on the surface of the base layer to obtain a multilayer ceramic capacitor 100.

(Comparative Examples 1 to 3)

In Comparative Examples 1 to 3, as shown in Table 1, the main component metal (Ni) powder of the conductive paste for forming internal electrodes had an average particle diameter of 120 nm, a standard deviation of particle diameter of 33, and a gradient of cumulative particle size distribution. 6 was used. As the common material, one having an average particle size of 29 nm, a standard deviation of particle size of 8.7, and a gradient of cumulative particle size distribution of 5 was used. The average temperature increase rate from room temperature to the maximum temperature was 45°C/min in Comparative Example 1, 55°C/min in Comparative Example 2, and 65°C/min in Comparative Example 3. Other conditions were carried out similarly to the Example.

Fig. 5(a) is a diagram showing the particle size distribution of the main component metal of the conductive paste for forming internal electrodes in Examples 1 to 5 and Comparative Examples 1 to 3. As shown in Fig. 5(a), it is understood that in Examples 1 to 5, metal powder having a small average particle diameter and a sharp particle size distribution is used. Further, in Comparative Examples 1 to 3, it can be seen that metal powder having a large average particle diameter and a broad particle size distribution is used. Fig. 5(b) is a diagram showing the particle size distribution of common materials of the conductive paste for forming internal electrodes in Examples 1 to 5 and Comparative Examples 1 to 3. As shown in (b) of FIG. 5 , it can be seen that in Examples 1 to 5, a common material having a small average particle diameter and a sharp particle size distribution was used. Further, in Comparative Examples 1 to 3, it can be seen that a common material having a large average particle diameter and a broad particle size distribution was used.

(analyze)

6(a) and 6(b) show SEM (scanning electron microscope) photographs of cross sections in the stacking direction of the dielectric layer 11 and the internal electrode layer 12 at the central portion in the width direction. it is a drawing Figure 6 (a) is a SEM picture of Example 3, Figure 6 (b) is a SEM picture of Comparative Example 2. From the results of FIG. 6(a) and FIG. 6(b), in the cross section of the internal electrode layer 12 in the stacking direction of the dielectric layer 11 and the internal electrode layer 12, particles containing ceramic as a main component The area ratio where (15) exists was measured. Specifically, the number of particles 15 is counted from the SEM image, each particle diameter is measured, and the area of the particles 15 relative to the total area of the internal electrode layer 12 (including the particles 15) By calculating the area ratio was calculated. The field of view of the SEM photograph was 12.6 µm x 8.35 µm. 6(c) and 7, the area ratio is 12.0 in Example 1, 14.5 in Example 2, 16.2 in Example 3, 17.3 in Example 4, and 18.0 in Example 5, as shown in FIG. 6(c) and FIG. was In Comparative Example 1, it was 7.0, in Comparative Example 2, it was 8.7, and in Comparative Example 3, it was 9.0.

In addition, the continuity rate described in FIG. 2 was measured using the obtained SEM photograph. In Examples 1 to 5, the continuity was 100%. In Comparative Examples 1 to 3, the continuity was 94 to 96%. Regarding the continuity rate, an average value was obtained by measuring the continuity rate of all internal electrode layers taken in several SEM photographs.

Next, the dielectric constant was evaluated for the samples of the multilayer ceramic capacitors according to Examples 1 to 5 and Comparative Examples 1 to 3. Specifically, capacitance was measured using an LCR meter 4284A from Hewlett Packard. The apparent dielectric constant was calculated from this measured value, the intersection area of the internal electrodes of the multilayer capacitor serving as the sample, the thickness of the dielectric ceramic layer, and the number of laminated layers. The number of samples was 100.

Permittivity was evaluated for each of 100 samples of Examples 1 to 5 and Comparative Examples 1 to 3. 8 is a graph showing the evaluation results of permittivity. The vertical axis in Fig. 8 represents the permittivity of each sample. In addition, in FIG. 8, the dielectric constant normalized by taking the average of the dielectric constants of the samples according to Example 3 as 100% is shown.

From the results of FIG. 8 , it can be seen that in Examples 1 to 5, the dielectric constant at the same heating rate was improved by 20% or more compared to Comparative Examples 1 to 3. This is because, by using a small-diameter material having a sharp particle size distribution as the metal material of the metal conductive paste for forming the internal electrode, the common material remains in the internal electrode layer 12 during the sintering process, and diffusion into the dielectric layer 11 is suppressed, and the dielectric layer ( It is thought that this is because the difference in A/B ratio or composition of the materials in 11) was suppressed.

Above, although the embodiment of the present invention has been described in detail, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

10: laminated chip
11: dielectric layer
12: internal electrode layer
13: cover layer
20a, 20b: external electrode
100: multilayer ceramic capacitor

Claims (11)

A laminated structure in which dielectric layers containing ceramics and internal electrode layers containing metals are alternately laminated,
The thickness of the internal electrode layer is 0.3 μm or less,
Particles containing ceramic are present in the internal electrode layer,
In a cross section of the internal electrode layer in the stacking direction of the dielectric layer and the internal electrode layer, a ratio of an area in which the particles exist is 10% or more and 100% or less,
In the internal electrode layer, in the region where the particle is present and the area ratio is 10% or more and 100% or less, there are at least two metal crystal grains in contact with any adjacent dielectric layer, and the two metal crystal grains are a grain boundary extending between adjacent dielectric layers is formed by the two metal crystal grains, the grains being disposed in the grain boundary;
The multilayer ceramic capacitor characterized in that the particles do not exist in an area of 5% above and below each in the thickness direction of the internal electrode layer. According to claim 1,
The multilayer ceramic capacitor, characterized in that the metal included in the internal electrode layer is nickel. According to claim 1,
A multilayer ceramic capacitor, characterized in that the ceramic included in the particles is barium titanate. According to claim 1,
The ceramic included in the dielectric layer is a multilayer ceramic capacitor, characterized in that barium titanate. According to claim 1,
The area ratio is obtained from the total area of the 10 internal electrode layers arbitrarily selected using SEM images of cross-sections of the internal electrode layers and the total area of the particles in the 10 internal electrode layers. Condenser. On a green sheet containing ceramic powder, metal powder having an average particle diameter of 100 nm or less and a standard deviation of particle size distribution of 15 or less is included, and ceramic powder having an average particle diameter of 10 nm or less and a standard deviation of particle size distribution of 5 or less is included. A first step of arranging a pattern of a metal conductive paste containing as
A second step of firing a ceramic laminate obtained by laminating a plurality of laminate units obtained in the first step to form an internal electrode layer by sintering the metal powder and forming a dielectric layer by sintering the ceramic powder of the green sheet. including process,
The thickness of the internal electrode layer is 0.3 μm or less,
In a cross section of the internal electrode layer in the stacking direction of the internal electrode layer and the dielectric layer, an area ratio in which ceramic-containing particles exist is set to 10% or more and 100% or less,
In the internal electrode layer, in the region where the particle is present and the area ratio is 10% or more and 100% or less, there are at least two metal crystal grains in contact with any adjacent dielectric layer, and the two metal crystal grains are The second step is performed so that a grain boundary extending between adjacent dielectric layers is formed by the two metal crystal grains, which are aligned and in contact with each other in the extension direction of the internal electrode layer, and the grain is disposed at the grain boundary; ,
A method for manufacturing a multilayer ceramic capacitor, characterized in that the particles are not present in an area of 5% above and below the internal electrode layer in the thickness direction. According to claim 6,
A method for manufacturing a multilayer ceramic capacitor characterized in that in the second step, the average heating rate from room temperature to the maximum temperature is set to 30°C/min or more and 80°C/min or less. According to claim 6,
The method of manufacturing a multilayer ceramic capacitor, characterized in that the metal powder contains nickel. According to claim 6,
The method of manufacturing a multilayer ceramic capacitor, characterized in that the common material contains barium titanate. According to claim 6,
The method of manufacturing a multilayer ceramic capacitor, characterized in that the ceramic powder of the green sheet contains barium titanate. According to claim 6,
The area ratio is obtained from the total area of 10 internal electrode layers arbitrarily selected using SEM images of cross-sections of internal electrode layers and the total area of the particles in the 10 internal electrode layers, characterized in that Manufacturing method of ceramic capacitor.

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