JP6904505B2 - Dielectric porcelain composition and multilayer ceramic capacitors containing it - Google Patents

Description

The present invention relates to a dielectric porcelain composition whose temperature characteristics and reliability are guaranteed for X8R or X9S and a multilayer ceramic capacitor containing the same.

Generally, electronic components using a ceramic material such as a capacitor, an inductor, a piezoelectric element, a varistor or a thermister include a ceramic body made of the ceramic material, an internal electrode formed inside the ceramic body, and the above internal electrode. It is provided with an external electrode installed on the surface of the ceramic body so as to be connected to the ceramic body.

Among the ceramic electronic components, the multilayer ceramic capacitor includes a plurality of laminated dielectric layers, an internal electrode arranged to face each other with one dielectric layer interposed therebetween, and an external electrode electrically connected to the internal electrode. ..

Multilayer ceramic capacitors are widely used as components of mobile communication devices such as computers, PDAs, and mobile phones because of their advantages of being small, guaranteed high capacity, and easy to mount.

A multilayer ceramic capacitor is usually produced by laminating an internal electrode paste and a dielectric layer paste by a sheet method, a printing method, or the like and simultaneously firing them.

In recent years, the proportion of electronic control devices in automobiles has been increasing, and with the development of hybrid automobiles and electric automobiles, the demand for multilayer ceramic capacitors that can be used at high temperatures of 150 ° C. or higher is gradually increasing.

Currently, there is a C0G-based dielectric as a dielectric material that can be fired in a reducing atmosphere and can be applied to a product guaranteed at 200 degrees, but the dielectric constant is as low as about 30, and a high-capacity product is manufactured. There is a problem that it is difficult to do.

In _{the case of BaTiO 3} , the dielectric constant is as high as 1000 or more, but since the dielectric constant drops sharply at a Curie temperature of 125 ° C or higher, it is not possible to guarantee the characteristics up to 200 ° C, which is a region of 150 ° C or higher. It is impossible.

As _{a method of raising the Curie temperature of BaTiO 3} , there is a method of solid-solving Pb in Ba-site, but in the case of Pb, it is classified as an environmentally regulated substance, and there are many restrictions on its use.

In addition, _{Bi (Mg 0.5} Ti _0.5 ) O ₃ , (Bi _0.5 Na _0.5 ) TiO ₃ , Bi (Zn _0.5 ), which is a perovskite material containing _{BaTiO 3 material and Bi.} It is known that materials such as Ti _0.5 ) O ₃ and BiScO ₃ raise the Curie temperature and realize a stable dielectric constant in the high temperature part, but such materials are fired only in an air atmosphere. Is possible.

That is, materials such as Bi (Mg _0.5 Ti _0.5 ) O ₃ , (Bi _0.5 Na _0.5 ) TiO ₃ , Bi (Zn _0.5 Ti _0.5 ) O ₃ , and BiScO ₃ are used. Therefore, when a multilayer ceramic capacitor including a Ni internal electrode is manufactured, there is a problem that the insulation resistance sharply decreases when firing in a reducing atmosphere, which makes it difficult to use.

_{Na (Nb, Ta) O 3} is known as a dielectric material for high-temperature capacitors that can be fired in a reducing atmosphere, but the prices of Nb and Ta, which are the starting materials for Na (Nb, Ta) O _{3, are very high.} There is a drawback that it occupies a large proportion of the material cost in mass production, and there is a problem that the insulation resistance characteristic is inferior to that of _{BaTiO 3.}

In addition, in _{the case of BaTi 2} O ₅ , it is known that the Curie temperature is about 500 degrees, but in _{the case of BaTi 2} O ₅ , it is possible to bake only in an air atmosphere, and reduction resistance and insulation resistance. There is a problem that it is inferior.

Therefore, it is necessary to develop a dielectric material that has a higher Curie temperature than _{BaTiO 3} and can realize normal insulation resistance even when firing in a reducing atmosphere.

JP-A-2009-256147

_{An object of the present invention is to provide a dielectric porcelain composition having a higher Curie temperature than BaTIO 3} even when firing in a reducing atmosphere and capable of realizing normal insulation resistance, and a multilayer ceramic capacitor containing the same. And.

The present invention also provides a dielectric porcelain composition capable of reducing atmosphere firing and having effects such as high dielectric constant, high insulation resistance and high Curie temperature, and a multilayer ceramic capacitor containing the same. With the goal.

The dielectric porcelain composition according to an embodiment of the present invention contains a base material powder containing a first main component and a second main component, and a sub component, and the first main component is ( _Ky Na _{1). -y) (a Nb 1-z Ta z) O} 3, the second principal component is BaTiO _3, the base powder is _{(1-x) (K y} Na 1-y) (Nb 1-z when a ta _{z) O 3} -xBaTiO 3, the x is 0.05 ≦ x ≦ 0.4, said y is 0 ≦ y ≦ 0.7, and z represents 0 ≦ z ≦ 0. 7.

The laminated ceramic capacitor according to another embodiment of the present invention includes a ceramic main body including a dielectric layer and an internal electrode, and an external electrode arranged outside the ceramic main body and connected to the internal electrode. The layer contains a first crystal grain and a second crystal grain, and the first crystal grain is a crystal grain having a Ba content of less than 10 at% and a Ti content of less than 10 at%, and the second crystal grain is described above. When the crystal grains are crystal grains having a Ba content of 10 at% or more and a Ti content of 10 at% or more, the area ratio of the second crystal grains to the total area is 4.7% to 37.9%. is there.

According to the dielectric porcelain composition and the multilayer ceramic capacitor according to the embodiment of the present invention, the target characteristics of the present invention are room temperature resistivity of 10 ¹¹ Ohm-cm or more, high temperature (200 degrees) withstand voltage of 50 V / μm or more, TCC. It is possible to simultaneously realize all the characteristics of (150 ° C.) less than ± 15%, TCC (200 ° C.) less than ± 22%, and a room temperature dielectric constant of 400 or more.

It is a schematic diagram with respect to the microstructure composed of the 1st crystal grain and the 2nd crystal grain, and the positions P1, P2, P3, P4 in which the content of Ba and Ti is analyzed by STEM / EDS analysis in each crystal grain. It is a schematic perspective view which shows the multilayer ceramic capacitor which concerns on one Embodiment of this invention. FIG. 5 is a schematic cross-sectional view showing a multilayer ceramic capacitor taken along III-III'of FIG.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention can be transformed into various other embodiments, and the scope of the invention is not limited to the embodiments described below. Also, embodiments of the present invention are provided to more fully explain the present invention to those having average knowledge in the art. Therefore, the shape and size of the elements in the drawings may be exaggerated for a clearer explanation.

The present invention relates to a dielectric porcelain composition, and examples of the electronic component containing the dielectric porcelain composition include a capacitor, an inductor, a piezoelectric element, a varistor, a thermister, and the like. A monolithic ceramic capacitor will be described as an example of the components.

Base powder of the dielectric ceramic composition according to an embodiment of the present invention _includes a first principal component represented by _{(K y Na 1-y)} (Nb 1-z Ta z) O 3, with BaTiO ₃ Includes the second principal component represented. In this case, base powder _is represented by _{(1-x) (K y} Na 1-y) (Nb 1-z Ta z) O 3 -xBaTiO 3.

When x satisfies 0.05 to 0.4, the room temperature resistivity, which is the target characteristic of the present invention, is 10 ¹¹ Ohm-cm or more, the high temperature (200 degrees) withstand voltage is 50 V / μm or more, and the TCC (150 ° C) ± 15 It is possible to simultaneously realize all the characteristics of less than%, TCC (200 ° C.) less than ± 22%, and room temperature resistivity of 400 or more.

Further, y may be 0 ≦ y ≦ 0.7, and z may be 0 ≦ z ≦ 0.7.

The dielectric porcelain composition according to one embodiment of the present invention is X8R (-55 ° C. to 150 ° C., ΔC / C ₀ ± 15%) or X9S (-55) specified in the EIA (Electronic Industries Association) standard. ° C to 200 ° C, ΔC / C ₀ ± 22%) characteristics can be satisfied.

More specifically, according to one embodiment of the present invention, nickel (Ni) is used as the internal electrode of the multilayer ceramic capacitor, and the insulation resistance can be maintained even when firing is performed in a reducing atmosphere in which nickel (Ni) is not oxidized. A dielectric porcelain composition is provided. Further, by providing a multilayer ceramic capacitor using the same, it is possible to simultaneously realize the effects of high dielectric constant, high insulation resistance and high Curie temperature.

In the present invention, including high high BaTiO ₃ and the Curie temperature of the dielectric constant (K, Na) and NbO ₃ both as a base material powder. Further, by applying a part of B-sited Nb of (K, Na) NbO ₃ as Ta, the insulation resistance is improved when firing in a reducing atmosphere.

Therefore, in the present invention, by using a dielectric porcelain composition that can be fired in a reducing atmosphere, a sample in the form of a composite composed of two types of crystal grains having different compositions in one sintered body is prepared. By controlling the area ratio of these two crystal grains, the target characteristics of the present invention can be realized.

Hereinafter, each component of the dielectric porcelain composition according to the embodiment of the present invention will be described in more detail.

a) base powder of the dielectric ceramic composition according to an embodiment of the base powder present _{invention, (K y Na 1-y} ) (Nb 1-z Ta z) O 3 ( however, y is 0 ≦ y ≦ 0.7, z includes a first principal component represented by 0 ≦ z ≦ 0.7) and a second principal component represented by _{BaTiO 3.} In this case, base powder _is represented by _{(1-x) (K y} Na 1-y) (Nb 1-z Ta z) O 3 -xBaTiO 3.

When x satisfies 0.05 to 0.4, the room temperature resistivity, which is the target characteristic of the present invention, is 10 ¹¹ Ohm-cm or more, the high temperature (200 degrees) withstand voltage is 50 V / μm or more, and the TCC (150 ° C) ± 15 It is possible to simultaneously realize all the characteristics of less than%, TCC (200 ° C.) less than ± 22%, and room temperature resistivity of 400 or more.

The first principal _{component, (K y Na 1-y} ) (Nb 1-z Ta z) represented by it can at _{O 3,} although the Curie temperature is different depending on the ratio of K and Na, y is 0.5 In this case, the Curie temperature is as high as about 400 degrees.

In the first principal component, when y is 0.1 or more, the room temperature dielectric constant can be improved to 800 or more, but when y exceeds 0.7, the room temperature specific resistance sharply decreases to 10. There is a problem that it drops to less than ^{11 Ohm-cm.} That is, y may be 0.1 to 0.7 in order to improve the room temperature dielectric constant to 800 or ^{more and maintain the room temperature resistivity to 10 11 Ohm-cm or more.}

Further, in the first principal component, the room temperature resistivity can be improved as z increases, but when z exceeds 0.7, there is a problem that the room temperature dielectric constant sharply decreases to less than 400. .. That is, z may be 0 to 0.7 in order to increase and maintain the room temperature resistivity and maintain the room temperature dielectric constant at 400 or more.

That is, K and Ta, which are the first principal components, have a complementary relationship. Therefore, by simultaneously containing K and Ta in the first principal component, the room temperature resistivity can ^{be maintained at 10 11} Ohm-cm or more, and the room temperature dielectric constant can be improved to 800 or more.

The second principal component may be represented by BaTiO _3, BaTiO ₃ is a material that is used for general dielectric base material, a ferroelectric material Curie temperature of approximately 125 degrees You may.

As the second main _{component, not only the component represented by BaTiO 3} but also Ca, Zr, etc. were partially dissolved and corrected (Ba _1-x Ca _x ) (Ti _1-y C _y ) O ₃ , form, such as _{Ba (Ti 1-y Zr y} ) O 3 are also possible.

That is, in the base material powder of the dielectric porcelain composition according to the embodiment of the present invention, the first principal component having a high Curie temperature and the second principal component having a high dielectric constant are mixed or solid-solved at a constant ratio. It may be in the form.

In the dielectric porcelain composition according to the embodiment of the present invention, the first principal component and the second principal component material are mixed at a constant ratio as described above to prepare a base material powder, which is used for reduction. Atmospheric firing is possible.

FIG. 1 is a schematic view of a microstructure composed of first crystal grains and second crystal grains and positions P1, P2, P3, and P4 in which the contents of Ba and Ti are analyzed by STEM / EDS analysis in each crystal grain.

Referring to FIG. 1, the microstructure of the dielectric layer produced (reducing atmosphere, firing temperature: 1100 to 1150 ° C.) using the dielectric porcelain composition according to the embodiment of the present invention has a Ba content of 10 at%. It includes first crystal grains having a Ti content of less than 10 at% and a Ti content of less than 10 at%, and second crystal grains having a Ba content of 10 at% or more and a Ti content of 10 at% or more.

The content of Ti and Ba in one crystal grain was derived from the average value of the data at each of the four locations by measuring the content (at%) of Ti and Ba at each location of P1 to P4.

The dielectric layer and the laminated ceramic capacitor using the dielectric porcelain composition according to the embodiment of the present invention can simultaneously have the effects of high dielectric constant, high insulation resistance and high Curie temperature.

More specifically, in the dielectric layer produced by using the dielectric porcelain composition according to the embodiment of the present invention and the multilayer ceramic capacitor containing the dielectric layer, the area ratio of the second crystal grains is 4. Since it is 7 to 37.9%, the room temperature resistivity, which is the target characteristic of the present invention, is 10 ¹¹ Ohm-cm or more, high temperature (200 degrees) withstand voltage 50 V / μm or more, and TCC (150 ° C) less than ± 15%. , TCC (200 ° C.) less than ± 22%, and room temperature dielectric constant of 400 or more can be realized at the same time.

Further, in the dielectric layer produced by using the dielectric porcelain composition according to the embodiment of the present invention and the multilayer ceramic capacitor containing the dielectric layer, the area ratio of the second crystal grains is 4.7 to 37 with respect to the total area. Since it is 9.9%, X8R (-55 ° C to 150 ° C, ΔC / C ₀ ± 15%) or X9S (-55 ° C to 200 ° C, ΔC) specified in the EIA (Electronic Inventions Association) standard. / C ₀ ± 22%) characteristics can be satisfied.

When the area ratio of the second crystal grains is less than 4.7% with respect to the total area, the room temperature resistivity is ^{less than 10 11} Ohm-cm, and when it exceeds 37.9%, X8R (-). There is a problem that the characteristics of 55 ° C. to 150 ° C., _{ΔC / C 0} ± 15%) or X9S (−55 ° C. to 200 ° C., ΔC / C ₀ ± 22%) cannot be satisfied.

That is, when the area ratio of the second crystal grain to the total area is different from 4.7% to 37.9%, a part of the target characteristics of the present invention cannot be realized.

The base material powder is not particularly limited, but the average particle size of the powder may be 300 nm or less.

b) First sub-component According to one embodiment of the present invention, the dielectric porcelain composition can further contain an oxide or carbonate containing Li as the first sub-component, preferably Li ₂ CO ₃ Can be further included. The first subcomponent can be contained in an amount of 0.25 mol to 5.0 mol with respect to 100 mol of the base material powder.

That is, the content of the first sub-component can be contained so that the content of the Li element in the _{Li 2} CO _{3 contained in 100 mol of the base material powder satisfies 0.5 mol to 10.0 mol.}

The first subcomponent serves to improve the room resistivity and the high temperature withstand voltage characteristics of the multilayer ceramic capacitor to which the dielectric porcelain composition is applied.

When the first subcomponent is less than 0.25 mol with respect to 100 mol of the base material powder, there arises a problem that the sintering density is low and the room temperature resistivity and the high temperature withstand voltage are very low, and the first subcomponent becomes If it exceeds 5.0 mol with respect to 100 mol of the base metal powder, there may be a problem that the high temperature resistivity is as low as less than 50 V / μm.

Therefore, the dielectric porcelain composition according to the embodiment of the present invention has all the above-mentioned properties when the content of the first subcomponent is 0.25 to 5.0 mol with respect to 100 mol of the base material powder. Simultaneous realization is possible. At this time as well, it can be seen that the area ratio of the second crystal grains to the total area satisfies 4.7% to 37.9%.

c) Second sub-component According to one embodiment of the present invention, the dielectric porcelain composition contains variable valence acceptors of Mn, V, Cr, Fe, Ni, Co, Cu and Zn as the second sub-component. It can further include one or more selected from the group consisting of oxides or carbonates of the Variable Valence Acceptor) element, preferably MnO ₂ or V ₂ O ₅ .

The oxide or carbonate containing at least one of Mn, V, Cr, Fe, Ni, Co, Cu and Zn as the second subcomponent is 0.1 mol to 3 for 100 mol of the base material powder. It can be contained in a content of 0.0 mol.

That is, the content of the second sub-component is such that the content of the variable valence acceptor element contained in the second sub-component satisfies 0.1 mol to 3.0 mol with respect to 100 mol of the base material powder. it can.

Alternatively, when two or more kinds of second subcomponents are contained, the total content of the valence variable acceptor elements contained in the second subcomponents should be 0.1 mol to 3.0 mol with respect to 100 mol of the base material powder. Can be included.

The second subcomponent serves to improve the room resistivity and the high temperature withstand voltage characteristics of the multilayer ceramic capacitor to which the dielectric porcelain composition is applied.

When the total content of the variable valence acceptor element contained in the second subcomponent is less than 0.1 mol, the room temperature resistivity and the high temperature withstand voltage characteristic may decrease.

Even when the total content of the variable valence acceptor element contained in the second subcomponent exceeds 3.0 mol, the resistivity at room temperature and the withstand voltage at high temperature may decrease.

In particular, in the dielectric porcelain composition according to the embodiment of the present invention, the total content of the variable valence acceptor element contained in the second subcomponent is 0.1 mol to 3.0 mol with respect to 100 mol of the base material powder. It can be included to satisfy, which enables low temperature firing, high high temperature withstand voltage characteristics, and simultaneous realization of all the above characteristics.

At this time as well, it can be seen that the area ratio of the second crystal grains to the total area satisfies 4.7% to 37.9%.

d) Third subcomponent According to one embodiment of the present invention, the dielectric porcelain composition is one or more selected from the group consisting of oxides of Si element, carbonates of Si element and glass containing Si element. A third subcomponent containing the above can be contained, and preferably, SiO ₂ can be further contained.

The third sub-component can be contained in an amount of 0.1 to 5.0 mol with respect to 100 mol of the base material powder. That is, the content of the third sub-component can be contained so that the content of the Si element in _{SiO 2 contained in 100 mol of the base material powder satisfies 0.1 mol to 5.0 mol.}

When the content of the third subcomponent is less than 0.1 mol with respect to 100 mol of the base material powder, the sintering density may be low and the room temperature resistivity and the high temperature withstand voltage may decrease. Even if it is contained in excess of 0.0 mol, the high temperature resistivity may be lowered due to problems such as secondary phase formation.

At this time as well, it can be seen that the area ratio of the second crystal grains to the total area satisfies 4.7% to 37.9%.

FIG. 2 is a schematic perspective view showing the multilayer ceramic capacitor 100 according to the embodiment of the present invention, and FIG. 3 is a schematic cross section showing the multilayer ceramic capacitor 100 taken along III-III'of FIG. It is a figure.

Referring to FIGS. 2 and 3, the multilayer ceramic capacitor 100 according to another embodiment of the present invention has a ceramic body 110 in which a dielectric layer 111 and first and second internal electrodes 121 and 122 are alternately laminated. At both ends of the ceramic body 110, first and second external electrodes 131 and 132 that are electrically connected to the first and second internal electrodes 121 and 122 that are alternately arranged inside the ceramic body 110 are formed.

The shape of the ceramic body 110 is not particularly limited, but may be generally a hexahedron shape. Further, the dimensions are not particularly limited, and may be appropriate dimensions depending on the application, for example, (0.6 to 5.6 mm) × (0.3 to 5.0 mm) × (0.3 to 1. 9 mm) may be used.

The thickness of the dielectric layer 111 can be arbitrarily changed according to the capacitance design of the capacitor, but in one embodiment of the present invention, the thickness of the dielectric layer after firing is preferably 0.1 μm per layer. It may be the above.

Since a dielectric layer having a thickness that is too thin has a small number of crystal grains existing in one layer and adversely affects reliability, the thickness of the dielectric layer may be 0.1 μm or more.

The first and second internal electrodes 121 and 122 are laminated so that their end faces are alternately exposed on the surfaces of the opposite end portions of the ceramic body 110.

The first and second external electrodes 131 and 132 are formed at both ends of the ceramic body 110 and are electrically connected to the exposed end faces of the first and second internal electrodes 121 and 122 which are alternately arranged. , Consists of a capacitor circuit.

The conductive material contained in the first and second internal electrodes 121 and 122 is not particularly limited, but the dielectric layer 111 according to the embodiment of the present invention is the dielectric porcelain composition according to the embodiment of the present invention. Is formed using.

Base powder of the dielectric ceramic composition according to an embodiment of the present _{invention, (K y Na 1-y} ) (Nb 1-z Ta z) O 3 ( however, y is 0 ≦ y ≦ 0.7, z includes a first principal component represented by 0 ≦ z ≦ 0.7) and a second principal component represented by _{BaTiO 3.} In this case, base powder _is represented by _{(1-x) (K y} Na 1-y) (Nb 1-z Ta z) O 3 -xBaTiO 3, x satisfies the 0.05 to 0.4.

The thicknesses of the first and second internal electrodes 121 and 122 can be appropriately determined depending on the application and the like, and are not particularly limited. For example, 0.1 to 5 μm or 0.1 to 2. It may be 5 μm.

The conductive material contained in the first and second external electrodes 131 and 132 is not particularly limited, but nickel (Ni), copper (Cu), or an alloy thereof may be used.

The thicknesses of the first and second external electrodes 131 and 132 can be appropriately determined depending on the intended use and the like, and are not particularly limited, but may be, for example, 10 to 50 μm.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but this is for the purpose of assisting a specific understanding of the invention, and the scope of the present invention is not limited to the Examples. ..

Ethanol and toluene were used as solvents in the compositions specified in Tables 1, 3 and 5 below, mixed with a dispersant, and then mixed with a binder to prepare a ceramic sheet.

As the main component base material, (K, Na) (Nb, Ta) O ₃ and BaTIO ₃ powder having an average particle size of 300 nm were used.

A nickel (Ni) electrode is printed on the molded ceramic sheet and 21 layers are laminated to prepare an active sheet, and a cover sheet (10 to 13 μm) is laminated on 25 layers as a cover located at the upper and lower parts of the active sheet. A crimping bar was produced by crimping.

Then, the crimping bar was cut into a chip having a size of 3.2 mm × 1.6 mm using a cutting machine.

The cut chips were calcined for _{debinding, and then fired in a reducing atmosphere (N 2} atmosphere) at 1100 to 1150 ° C., and an external electrode was formed on the fired chips with Cu paste.

For the prototype multilayer ceramic capacitor (Proto-type MLCC) test piece completed as described above, the capacitance and dielectric loss (DF) at room temperature are 1 kHz and AC 0.5 V / μm using an LCR meter. It was measured.

The dielectric constant of the dielectric of the laminated ceramic capacitor was calculated from the capacitance, the thickness of the dielectric of the laminated ceramic capacitor, the area of the internal electrode, and the number of layers.

The room temperature insulation resistance was measured after 60 seconds had passed with 10 samples taken at a time and DC 10 V / μm applied.

The change in capacitance with temperature was measured in the temperature range of −55 ° C. to 200 ° C.

In the high-temperature IR boosting experiment, the resistance deterioration behavior was measured while increasing the voltage step by 5 V / μm at 200 ° C., and at this time, the time of each step was 10 minutes, and the resistance value was measured at 5-second intervals.

The high-temperature withstand voltage was derived from the high-temperature IR boosting experiment. The high-temperature withstand voltage was measured by applying a DC voltage of 5 V / μm per unit thickness of the dielectric at 200 ° C. for 10 minutes and continuously increasing the voltage step. when in, which means the voltage that IR is equal to or greater than 10 ⁵ Ω.

The RC value is a value obtained by multiplying the normal temperature capacitance value measured at AC 0.5 V / μm and 1 kHz by the insulation value measured at DC 10 V / μm.

Tables 2, 4, and 6 show the characteristics of prototype multilayer ceramic capacitors (Proto-type MLCCs) to which nickel (Ni) internal electrodes corresponding to the compositions specified in Tables 1, 3, and 5 are applied. Shown.

Examples 1-10 in Table 1, base powder _{(1-x) (K y} Na 1-y) (Nb 1-z Ta z) O 3 -xBaTiO 3 (y, z = 0.2): 100mol On the other hand, when the first sub-component Li ₂ CO ₃ : 2.5 mol, the second sub-component MnO ₂ : 0.5 mol, and the third sub-component SiO ₂ : 0.5 mol, an example using x is shown. Table 2 shows the prototype laminated ceramic capacitors fired in a reducing atmosphere containing a dielectric layer prepared using the dielectric porcelain compositions of Examples 1 to 10 in Table 1 and a nickel (Ni) internal electrode. Shows the characteristics.

When the composition ratio x of the second main component BaTiO ₃ is less than 0.05 (Examples 1 and 2), the room temperature resistivity is ^{as low as less than 10 11} Ohm-cm, and the high temperature withstand voltage is less than 50 V / μm. There is a problem that it becomes low.

When the composition ratio x of the second main component BaTiO ₃ exceeds 0.4 (Examples 9 and 10), it exceeds high temperature (150 ° C.) TCC (150 ° C.) ± 15% and high temperature (200 ° C.). There is a problem that TCC (200 ° C.) exceeds ± 22%.

That is, when the _{composition ratio x of the second main component BaTiO 3} satisfies the range of 0.05 to 0.4 (Examples 3 to 8), the room temperature resistivity of the present invention is 10 ¹¹ Ohm-cm or more, and the temperature is high (1 11 Ohm-cm or more). (200 degrees) Withstand voltage of 50 V / μm or more, TCC (150 ° C) less than ± 15%, TCC (200 ° C) less than ± 22%, and room temperature dielectric constant of 400 or more can all be realized at the same time.

Using the dielectric porcelain composition according to one embodiment of the present invention, a dielectric layer is produced by firing at 1100 ° C. to 1150 ° C. in _{a reducing atmosphere (N 2 atmosphere), or inside nickel (Ni).} When the electrode is printed to manufacture a laminated ceramic capacitor, the microstructure of the dielectric layer includes first crystal grains and second crystal grains.

The contents of Ba and Ti at a total of 4 points of P1 to P4 in one crystal grain were analyzed by STEM / WDS or STEM / EELS.

As a result of calculation using the average values of the Ba and Ti contents at the four locations, the first crystal grain is defined as a crystal grain having a "Ba content of less than 10 at% and a Ti content of less than 10 at%". 2 crystal grains are defined as crystal grains having a Ba content of 10 at% or more and a Ti content of 10 at% or more.

Referring to Examples 1 to 10 in Table 1, in order to achieve the target characteristics of the present invention, the dielectric layer of the multilayer ceramic capacitor includes the first and second crystal grains, and the second crystal grain with respect to the total area. The area ratio of is required to be 4.7% to 37.9%.

That is, when observing the microstructure of the dielectric layer of the multilayer ceramic capacitor, the room temperature resistivity of the present invention is 10 when the area ratio of the second crystal grains per unit area is 4.7% to 37.9%. ¹¹ Ohm-cm or more, high temperature (200 degrees) withstand voltage 50 V / μm or more, TCC (150 ° C) less than ± 15%, TCC (200 ° C) less than ± 22%, and room temperature dielectric constant 400 or more at the same time It can be realized.

Example of Table 3 11 to 17, base powder _{0.9 (K y Na 1-y} ) (Nb 1-z Ta z) O 3 -0.1BaTiO 3 (z = 0.2): to 100mol The example according to y is shown when the first sub-component Li ₂ CO ₃ : 2.5 mol, the second sub-component MnO ₂ : 0.5 mol, and the third sub-component SiO _{2: 0.5 mol.} Table 4 shows the characteristics of a prototype laminated ceramic capacitor fired in a reducing atmosphere containing a dielectric layer prepared using the dielectric porcelain compositions of Examples 11 to 17 of Table 3 and a nickel (Ni) internal electrode. Shown.

It can be seen that the room temperature dielectric constant improves as the value of the composition ratio y of K of the first main component increases, but when the value of the composition ratio y of K exceeds 0.7 (Example 17), the room temperature There arises a problem that the specific resistance is ^{reduced to less than 10 11} Ohm-cm and the high temperature withstand voltage is lowered to less than 50 V / μm.

That is, when the value of the composition ratio y of K is 0.7 or less (Examples 11 to 16), the room temperature ratio resistance of the present invention is 10 ¹¹ Ohm-cm or more, and the high temperature (200 degrees) withstand voltage 50 V / μm. As described above, it is possible to simultaneously realize all the characteristics of TCC (150 ° C.) less than ± 15%, TCC (200 ° C.) less than ± 22%, and room temperature dielectric constant of 400 or more.

Further, in order to improve the room temperature dielectric constant to 800 or more, the value of the composition ratio y of K may be 0.1 or more. As the value of y increases, the room temperature dielectric constant tends to increase and then decrease. When the value of y exceeds 0.7 as described above (Example 17), the room temperature resistivity is 10 ¹¹ Ohm. The problem arises that the voltage decreases to less than -cm and the high temperature resistivity becomes as low as less than 50 V / μm. Therefore, in order to improve the room temperature dielectric constant to 800 or ^{more, maintain the room temperature resistivity to 10 11} Ohm-cm or more, and maintain the high temperature withstand voltage to 50 V / μm or more, the value of y is 0.1 to 0. .7 can be satisfied.

Also at this time, it can be seen that the area ratio of the second crystal grains to the total area belongs to the range of 4.7% to 37.9%.

The examples in Table 3 18-23 base powder _{0.9 (K y Na 1-y} ) (Nb 1-z Ta z) O 3 -0.1BaTiO 3 (y = 0.2): to 100mol The example using z is shown when the first sub-component Li ₂ CO ₃ : 2.5 mol, the second sub-component MnO ₂ : 0.5 mol, and the third sub-component SiO _{2: 0.5 mol.} Table 4 shows the characteristics of the prototype laminated ceramic capacitor fired in a reducing atmosphere containing the dielectric layer prepared using the dielectric porcelain compositions of Examples 18 to 23 in Table 3 and the nickel (Ni) internal electrode. Shown.

It can be seen that the room temperature resistivity improves as the value of the composition ratio z of Ta of the first principal component increases, but when the value of the composition ratio z of Ta exceeds 0.7 (Example 23), the room temperature is normal. There arises a problem that the dielectric constant is as low as less than 400.

That is, when the value of the composition ratio z of Ta is 0.7 or less (Examples 18 to 22), the room temperature resistivity of the present invention is 10 ¹¹ Ohm-cm or more, and the high temperature (200 degrees) withstand voltage 50 V / μm. As described above, all the characteristics of TCC (150 ° C.) less than ± 15%, TCC (200 ° C.) less than ± 22%, and room temperature resistivity of 400 or more can be realized at the same time.

Also at this time, it can be seen that the area ratio of the second crystal grains to the total area belongs to the range of 4.7% to 37.9%.

As described above, the first principal components K and Ta have a complementary relationship. Therefore, by simultaneously containing K and Ta in the first principal component and appropriately adjusting each composition ratio, the room temperature resistivity can ^{be maintained at 10 11} Ohm-cm or more, and the room temperature dielectric constant can be improved to 800 or more. ..

Example 24-30 in Table 5, base powder _{0.9 (K y Na 1-y} ) (Nb 1-z Ta z) O 3 -0.1BaTiO 3 (y, z = 0.2): 100mol On the other hand, when the second sub-component MnO ₂ : 0.5 mol and the third sub-component SiO ₂ : 0.5 mol, an example based on the content of the first sub-component Li ₂ CO _{3 is shown.} Table 6 shows the characteristics of the prototype laminated ceramic capacitor fired in a reducing atmosphere containing the dielectric layer prepared using the dielectric porcelain compositions of Examples 24 to 30 in Table 5 and the nickel (Ni) internal electrode. ..

When the content of the first subcomponent Li ₂ CO ₃ is less than 0.25 mol with respect to 100 mol of the base material powder (Example 24), the sintering density is low and the room resistivity and the high temperature withstand voltage are very high. When the problem of lowness occurs and _{the content of the first subcomponent Li 2} CO ₃ exceeds 5.0 mol with respect to 100 mol of the base metal powder (Example 30), the high temperature resistivity is as low as less than 50 V / μm. The problem occurs.

That is, when the _{content of the first subcomponent Li 2} CO ₃ belongs to the range of 0.25 mol to 5.0 mol with respect to 100 mol of the base material powder (Examples 25 to 29), the room temperature resistivity of the present invention is 10. ¹¹ Ohm-cm or more, high temperature (200 degrees) withstand voltage 50 V / μm or more, TCC (150 ° C) less than ± 15%, TCC (200 ° C) less than ± 22%, and room temperature dielectric constant 400 or more at the same time It can be realized.

Also at this time, it can be seen that the area ratio of the second crystal grains to the total area belongs to the range of 4.7% to 37.9%.

Example 31-37 in Table 5, base powder _{0.9 (K y Na 1-y} ) (Nb 1-z Ta z) O 3 -0.1BaTiO 3 (y, z = 0.2): 100mol On the other hand, when the first sub-component Li ₂ CO ₃ : 2.5 mol and the third sub-component SiO ₂ : 0.5 mol, an example based on the content of the second sub-component MnO _{2 is shown.} Table 6 shows the characteristics of the prototype laminated ceramic capacitor fired in a reducing atmosphere containing the dielectric layer prepared using the dielectric porcelain compositions of Examples 31 to 37 of Table 5 and the nickel (Ni) internal electrode. ..

When the content of the second subcomponent MnO ₂ is less than 0.1 mol with respect to 100 mol of the base metal powder (Example 31), the problem of very low resistivity at room temperature and withstand voltage at high temperature occurs, and the second subcomponent Even when the content of the 2 sub-component MnO ₂ is an excessive amount of about 5.0 mol with respect to 100 mol of the base metal powder (Example 37), there is a problem that the resistivity at room temperature and the withstand voltage at high temperature are lowered.

That is, when the _{content of the second subcomponent MnO 2} belongs to the range of 0.1 mol to 3.0 mol with respect to 100 mol of the base material powder (Examples 32 to 36), the room temperature resistivity of the present invention is 10 ¹¹ Ohm. Simultaneous realization of all characteristics of -cm or more, high temperature (200 degrees) withstand voltage 50 V / μm or more, TCC (150 ° C) ± 15% or less, TCC (200 ° C) ± 22% or more, and room temperature dielectric constant 400 or more It is possible.

Also at this time, it can be seen that the area ratio of the second crystal grains to the total area belongs to the range of 4.7% to 37.9%.

Example 38-44 in Table 5, base powder _{0.9 (K y Na 1-y} ) (Nb 1-z Ta z) O 3 -0.1BaTiO 3 (y, z = 0.2): 100mol On the other hand, when the first sub-component Li ₂ CO ₃ : 2.5 mol and the second sub-component MnO ₂ : 0.5 mol are used, an example based on the content of _{the third sub-component SiO 2 is shown.} Table 6 shows the characteristics of the prototype laminated ceramic capacitor fired in a reducing atmosphere containing the dielectric layer prepared using the dielectric porcelain compositions of Examples 38 to 44 of Table 5 and the nickel (Ni) internal electrode. ..

When the content of the third subcomponent SiO ₂ is less than 0.1 mol with respect to 100 mol of the base metal powder (Example 38), there is a problem that the sintering density is low and the room resistivity and the high temperature withstand voltage are low. Even when the content of the third subcomponent SiO ₂ is excessive, about 7 mol with respect to 100 mol of the base metal powder (Example 44), there is a problem that the high temperature resistivity is lowered due to the formation of the secondary phase or the like. ..

That is, when the _{content of the third auxiliary component SiO 2} is 0.1 mol to 5.0 mol with respect to 100 mol of the base material powder (Examples 39 to 43), the room temperature resistivity of the present invention is 10 ¹¹ Ohm-cm. As mentioned above, it is possible to simultaneously realize all the characteristics of high temperature (200 ° C) withstand voltage of 50 V / μm or more, TCC (150 ° C) less than ± 15%, TCC (200 ° C) less than ± 22%, and normal temperature dielectric constant of 400 or more. is there.

Also at this time, it can be seen that the area ratio of the second crystal grains to the total area belongs to the range of 4.7% to 37.9%.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited to this, and various modifications and modifications are made within the scope of the technical idea of the present invention described in the claims. It is clear to those with ordinary knowledge in the art that this is possible.

100 Multilayer Ceramic Capacitor 110 Ceramic Body 111 Dielectric Layers 121, 122 First and Second Internal Electrodes 131, 132 First and Second External Electrodes

Claims (6)

A base material powder containing a first principal component and a second principal component, and an auxiliary component,
The first principal component is a _{(K y Na 1-y)} (Nb 1-z Ta z) O 3, the second principal component is BaTiO _3,
When the base powder is _{(1-x) (K y} Na 1-y) (Nb 1-z Ta z) O 3 -xBaTiO 3,
The x is 0.05 ≦ x ≦ 0.4.
The y is 0.1 ≦ y ≦ 0.7.
Wherein z Ri is 0 <z ≦ 0.7 der,
The sub-component contains a first sub-component and contains
The first subcomponent comprises any one or more selected from Li-containing oxides or carbonates.
The content of the first subcomponent, the content of Li elements Ru 0.5mol~10.0mol der against base powder 100 mol, the dielectric ceramic composition. The sub-ingredient contains a second sub-ingredient
The second subcomponent is one or more selected from the group consisting of oxides or carbonates of Mn, V, Cr, Fe, Ni, Co, Cu and Zn valence variable acceptor elements. Including
The content of the second subcomponent, the content of valence variable acceptor element contained in the second subcomponent being 0.1mol~3.0mol against base powder 100 mol, of claim 1 Dielectric porcelain composition. The sub-ingredient contains a third sub-ingredient
Containing one or more selected from the group consisting of oxides of Si element, carbonates of Si element and glass containing Si element.
The dielectric porcelain composition according to claim 1 or 2 , wherein the content of the third subcomponent is 0.1 mol to 5.0 mol of the Si element with respect to 100 mol of the base material powder. A ceramic body including a dielectric layer and internal electrodes,
Includes an external electrode located outside the ceramic body and connected to the internal electrode.
The dielectric layer contains K, Na, Nb and Ta, and the dielectric layer contains first crystal grains and second crystal grains.
The first crystal grain is a crystal grain having a Ba content of less than 10 at% and a Ti content of less than 10 at%, and the second crystal grain has a Ba content of 10 at% or more and a Ti content of 10 at%. When it is a crystal grain that is above
Area ratio of the second crystal grains to the total area of Ri 4.7% ～37.9% der,
The dielectric layer contains a base material powder containing a first principal component and a second principal component, and an auxiliary component.
The first principal component is a _{(K y Na 1-y)} (Nb 1-z Ta z) O 3, the second principal component is BaTiO _3,
When the base powder is _{(1-x) (K y} Na 1-y) (Nb 1-z Ta z) O 3 -xBaTiO 3, wherein x is 0.05 ≦ x ≦ 0.4 , The y is 0.1 ≦ y ≦ 0.7, and the z is 0 <z ≦ 0.7.
The sub-component contains a first sub-component and contains
The first subcomponent comprises any one or more selected from Li-containing oxides or carbonates.
The content of the first subcomponent, the content of Li elements Ru 0.5mol~10.0mol der against base powder 100 mol, laminated ceramic capacitors. The multilayer ceramic capacitor according to claim 4 , wherein the internal electrode contains nickel (Ni). Room resistivity is 10 ¹¹ Ohm-cm or more,
High temperature (200 degrees) withstand voltage 50V / μm or more,
TCC (150 ° C) less than ± 15%,
The multilayer ceramic capacitor according to claim 4 or 5 , which satisfies TCC (200 ° C.) less than ± 22% and a room temperature dielectric constant of 800 or more.

Images