JP2009203089A - Dielectric ceramic composition and electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric ceramic composition which shows high dielectric constant and good temperature characteristic, even after being processed into a thin film, and shows good characteristics such as CR product, breakdown voltage, DC bias characteristic and high-temperature accelerated life test characteristic. <P>SOLUTION: The dielectric ceramic composition comprises BaTiO<SB>3</SB>as a main component and further comprises, relative to 100 mol of the main component, 0.50-3.0 mol MgO, 0.05-0.5 mol MnO, an oxide (RE<SP>1</SP><SB>2</SB>O<SB>3</SB>) of an element chosen from the group consisting of Sm, Eu and Gd, an oxide (RE<SP>2</SP><SB>2</SB>O<SB>3</SB>) of an element chosen from the group consisting of Tb and Dy, an oxide (RE<SP>3</SP><SB>2</SB>O<SB>3</SB>) of an element chosen from the group consisting of Y, Ho, Er, Yb, Tm and Lu, 0.20-1.0 mol BaZrO<SB>3</SB>and 0.05-0.25 mol oxide of an element chosen from the group consisting of V, Ta, Mo, Nb and W as subcomponents, wherein contents of RE<SP>1</SP><SB>2</SB>O<SB>3</SB>, RE<SP>2</SP><SB>2</SB>O<SB>3</SB>and RE<SP>3</SP><SB>2</SB>O<SB>3</SB>satisfy the relations: RE<SP>1</SP><SB>2</SB>O<SB>3</SB><RE<SP>2</SP><SB>2</SB>O<SB>3</SB>and (RE<SP>1</SP><SB>2</SB>O<SB>3</SB>+RE<SP>2</SP><SB>2</SB>O<SB>3</SB>)≤RE<SP>3</SP><SB>2</SB>O<SB>3</SB>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a dielectric ceramic composition used as, for example, a dielectric layer of a multilayer ceramic capacitor, and an electronic component using the dielectric ceramic composition as a dielectric layer.

  A multilayer ceramic capacitor, which is an example of an electronic component, is obtained by, for example, firing a green chip obtained by alternately stacking ceramic green sheets made of a predetermined dielectric ceramic composition and internal electrode layers of a predetermined pattern and then integrating them. Manufactured. Since the internal electrode layer of the multilayer ceramic capacitor is integrated with the ceramic dielectric by firing, it is necessary to select a material that does not react with the ceramic dielectric. For this reason, as a material constituting the internal electrode layer, conventionally, an expensive noble metal such as platinum or palladium has been inevitably used.

On the other hand, in recent years, dielectric ceramic compositions that can use inexpensive base metals such as nickel and copper have been developed, and a significant cost reduction has been realized. As such a dielectric ceramic composition, for example, Patent Document 1 discloses {BaO} _m TiO ₂ + M ₂ O ₃ + R ₂ O ₃ + BaZrO ₃ + MgO + MnO (M ₂ O ₃ is Sc ₂ O ₃ and / or Y ₂ O). ₃ and R ₂ O ₃ are Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ ) main component 100 parts by weight, and Li ₂ O— (Si, Ti) O ₂ -MO (MO is _Al 2 _{O 3} and / or ZrO ₂₎ or _{SiO 2} -TiO 2 -XO (XO is BaO, CaO, SrO, MgO, ZnO, at least one of MnO) system subcomponent 0.2 A dielectric ceramic composition containing ˜3.0 parts by weight is disclosed.

The above-mentioned Patent Document 1 aims to provide a multilayer ceramic capacitor excellent in DC bias characteristics and weather resistance performance while improving the CR product under high electric field strength. However, in this Patent Document 1, the relative dielectric constant of the capacitor is as low as about 1500, and in addition to the problem of not being able to cope with the reduction in size and capacity, the interlayer thickness of the dielectric layer in a specific example is 30 μm. There has also been a problem that the dielectric layer cannot be made thinner.
JP 11-92220 A

  With the recent progress in downsizing, higher functionality, and higher performance of electronic devices, there is a continuing demand for monolithic ceramic capacitors that are smaller and have a larger capacity. For this, measures such as realization of a high relative dielectric constant by improving the dielectric material and increasing the number of layers by reducing the thickness of the dielectric layer are often adopted. As the thickness is further reduced, it is more difficult to ensure reliability such as life. In addition, miniaturization and higher functionality increase the density of electronic circuits, which increases the temperature rise due to heat generation during use, and increases the opportunity for outdoor use such as portable devices. Small change is also required more severely than before. For this reason, even when the layer is thinned, it has been required to improve the temperature characteristics of the capacitance while maintaining a high relative dielectric constant (for example, 3500 or more). However, as described above, the capacitor disclosed in Patent Document 1 does not consider the thinning of the dielectric layer, and when the layer is thinned, it achieves good temperature characteristics while maintaining a high relative dielectric constant. It was difficult.

  The present invention has been proposed in order to solve the above-described problems of the prior art, and its purpose is to achieve a high temperature while exhibiting a high relative dielectric constant even when thinned. An object of the present invention is to provide a dielectric magnetic composition having characteristics and good characteristics such as CR product, breakdown voltage, DC bias characteristics, and high temperature accelerated lifetime. Another object of the present invention is to provide an electronic component such as a multilayer ceramic capacitor having a dielectric layer composed of the dielectric ceramic composition and an internal electrode layer.

  As a result of intensive studies in order to achieve the above object, the present inventors have found that the above object can be achieved by using a dielectric ceramic composition having a specific composition, and the present invention has been completed. .

That is, the dielectric ceramic composition according to the present invention for solving the above problems is
BaTiO ₃ as a main component,
For 100 mol of the main component, as an auxiliary component, in terms of each oxide or composite oxide,
MgO: 0.50 to 3.0 mol,
MnO: 0.05 to 0.5 mol,
Sm, Eu, oxide of an element selected from the group consisting of ^{_{Gd (RE 1 2 O 3)}} ,
An oxide (RE ² ₂ O ₃ ) of an element selected from the group consisting of Tb and Dy,
An oxide (RE ³ ₂ O ₃ ) of an element selected from the group consisting of Y, Ho, Er, Yb, Tm, and Lu,
BaZrO ₃ : 0.20 to 1.0 mol, and an oxide of an element selected from the group consisting of V, Ta, Mo, Nb, and W: 0.05 to 0.25 mol,
The content of RE ¹ ₂ O ₃ , RE ² ₂ O ₃ and RE ³ ₂ O ₃ is
RE ¹ ₂ O ₃ <RE ² ₂ O ₃ and (RE ¹ ₂ O ₃ + RE ² ₂ O ₃ ) ≦ RE ³ ₂ O ₃
Meet.

Preferably, the content of RE ¹ ₂ O ₃ , RE ² ₂ O ₃ and RE ³ ₂ O ₃ with respect to 100 mol of the main component is
0.30 mol ≦ (RE ¹ ₂ O ₃ + RE ² ₂ O ₃ + RE ³ ₂ O ₃ ) ≦ 1.50 mol is satisfied.

  Preferably, 0.40 to 2.0 mol of a sintering aid is further contained as a subcomponent with respect to 100 mol of the main component.

Preferably, the RE ¹ is Gd, the RE ² is Dy, and the RE ³ is Y.

Preferably, Ba / Ti indicating the molar ratio of Ba and Ti in the BaTiO ₃ is 0.997 to 1.003.

Preferably, c / a indicating the ratio of the c-axis lattice constant to the a-axis lattice constant in the BaTiO ₃ crystal lattice is 1.0095 or more.

  The electronic component according to the present invention includes a dielectric layer made of the dielectric ceramic composition described above and an internal electrode layer. Although it does not specifically limit as an electronic component, A multilayer ceramic capacitor, a piezoelectric element, a chip inductor, a chip varistor, a chip thermistor, a chip resistor, and other surface mount (SMD) chip type electronic components are illustrated.

  According to the dielectric ceramic composition of the present invention, even when the layer thickness is 0.5 to 2.0 μm, the capacitance-temperature characteristic (for example, EIA standard) is achieved while realizing a high relative dielectric constant (for example, 3500 or more). X5R characteristics and X6S characteristics) can be satisfied, and the CR product, IR life, breakdown voltage, and DC bias characteristics can be improved.

  Therefore, in electronic parts having a dielectric layer composed of the above dielectric ceramic composition, particularly in a multilayer ceramic capacitor, the dielectric layer is thinned, and a large capacity is realized by the excellent characteristics of the dielectric. However, high reliability is ensured even under severe use environments.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.
FIG. 2 is a flowchart showing a manufacturing process of the multilayer ceramic capacitor according to one embodiment of the present invention.

  As shown in FIG. 1, a multilayer ceramic capacitor 1 according to an embodiment of the present invention includes a capacitor element body 10 having a configuration in which dielectric layers 2 and internal electrode layers 3 are alternately stacked. At both ends of the capacitor element body 10, a pair of external electrodes 4 are formed which are electrically connected to the internal electrode layers 3 arranged alternately in the element body 10. The shape of the capacitor element body 10 is not particularly limited, but is usually a rectangular parallelepiped shape. Moreover, there is no restriction | limiting in particular also in the dimension, What is necessary is just to set it as a suitable dimension according to a use.

  The internal electrode layers 3 are laminated so that the end faces are alternately exposed on the surfaces of the two opposite ends of the capacitor element body 10. The pair of external electrodes 4 are formed at both ends of the capacitor element body 10 and are connected to the exposed end surfaces of the alternately arranged internal electrode layers 3 to constitute a capacitor circuit.

The dielectric layer 2 contains the dielectric ceramic composition of the present invention.
The dielectric ceramic composition of the present invention includes BaTiO ₃ as a main component, an oxide (RE ¹ ₂ O ₃ ) of an element selected from the group consisting of MgO, MnO, Sm, Eu, and Gd as a subcomponent, Tb. , Oxides of elements selected from the group consisting of Dy (RE ² ₂ O ₃ ), oxides of elements selected from the group consisting of Y, Ho, Er, Yb, Tm, and Lu (RE ³ ₂ O ₃ ), BaZrO ₃ and an oxide of an element selected from the group consisting of V, Ta, Mo, Nb, and W. At this time, the amount of oxygen (O) may be slightly deviated from the stoichiometric composition of the above formula.

BaTiO ₃ as a main component has a perovskite-type crystal structure, and Ba occupies the A site and Ti occupies the B site. In the present embodiment, Ba / Ti indicating the molar ratio of Ba and Ti is preferably 0.997 to 1.003, more preferably 0.998 to 1.002, and still more preferably 0.998 to 1. It is in the range of 001. If Ba / Ti is too small, abnormal grain growth of the dielectric layer tends to occur during firing, and the capacity-temperature characteristics, DC bias characteristics, and IR lifetime tend to deteriorate. On the other hand, if Ba / Ti is too large, not only the relative dielectric constant tends to decrease, but also the sinterability tends to decrease and the firing temperature tends to increase, causing structural defects (delamination and cracks). turn into.

The perovskite crystal structure changes depending on the temperature, and becomes a tetragonal system at room temperature below the Curie point and becomes a cubic system above the Curie point. In the cubic system, each crystal axis (a axis, b axis, c axis) has the same lattice constant, but in the tetragonal system, the lattice constant of one axis (c axis) is the other axis (a axis). (= B axis)) is longer than the lattice constant. Therefore, in the tetragonal system, each ion (Ba ²⁺ , Ti ⁴⁺ , O ²⁻ ) constituting the crystal is displaced, the center of gravity of the positive and negative charges is shifted, and spontaneous polarization occurs. As a result, tetragonal BaTiO ₃ exhibits a higher relative dielectric constant than cubic BaTiO ₃ . In the present embodiment, c / a indicating the ratio between the c-axis lattice constant and the a-axis lattice constant is preferably 1.0095 or more, more preferably 1.0097 or more, and even more preferably 1.0098 or more. . If c / a is too small, a high relative dielectric constant tends not to be obtained, and the reaction between BaTiO ₃ and subcomponents is difficult to suppress, so that the fired dielectric particles form a clear core-shell structure. It tends to be difficult.
In addition, it is not necessary for c / a of all BaTiO ₃ particles to satisfy the above range. That is, for example, raw material powder of BaTiO _3, the BaTiO ₃ particles tetragonal may coexist and the BaTiO ₃ particles of cubic, as BaTiO ₃ whole of the raw material powder, tetragonality is high, c / a may be in the above range.

  MgO as an auxiliary component has an effect of flattening the capacity-temperature characteristics, and is 0.50 to 3.0 mol, preferably 1.0 to 3.0 mol, in terms of MgO, with respect to 100 mol of the main component. More preferably, it is contained in an amount of 1.5 to 2.5 mol. If the content of MgO is too small, rapid grain growth occurs during sintering, and desired capacity-temperature characteristics and DC bias characteristics cannot be obtained. On the other hand, if the content of MgO is too large, the relative dielectric constant decreases and the capacity-temperature characteristics tend to deteriorate.

  MnO has the effect of promoting sintering, the effect of increasing the insulation resistance IR, and the effect of improving the IR life, and 0.05 to 0.5 mol in terms of MnO with respect to 100 mol of the main component. , Preferably 0.05 to 0.4 mol, more preferably 0.10 to 0.35 mol. When the content of MnO is too small, the insulation resistance is greatly lowered, and the CR product and reliability are also lowered. Moreover, when there is too much content of MnO, while there exists a tendency for an insulation resistance (IR) to fall and for a dielectric constant and sinterability to fall.

RE ¹ , RE ² and RE ³ classify rare earth elements by ion radius, RE ¹ is an element selected from the group consisting of Sm, Eu and Gd, and RE ² is from the group consisting of Tb and Dy. elements selected, RE ³ is an element selected Y, Ho, Er, Yb, Tm, from the group consisting of Lu.

The present invention is characterized by combining three kinds of rare earth oxides selected from each of RE ¹ , RE ² and RE ³ , the content of which is RE ¹ ₂ O ₃ <RE ² ₂ O ₃ and (RE ¹ ₂ O ₃ + RE ² ₂ O ₃ ) ≦ RE ³ ₂ O ₃

Further, the total content of RE ¹ ₂ O ₃ , RE ² ₂ O ₃ , and RE ³ ₂ O ₃ with respect to 100 mol of the main component is preferably 0.30 mol to 1.50 mol, more preferably 0.8. 30 mol to 1.25 mol.

By satisfying the above content relationship, it is possible to improve the reliability while suppressing the diffusion of the rare earth into the core. Even if the element selected in the group of rare earth element oxides of RE ¹ , RE ² , and RE ³ is changed, it shows substantially the same characteristics, but preferably, RE ¹ is Gd, RE ² is Dy, RE ³ is Y.
If the amount of RE ¹ ₂ O ₃ added exceeds RE ² ₂ O ₃ , the capacity-temperature change rate on the high temperature side deteriorates. Also, the relative permittivity tends to decrease due to the diffusion of RE ¹ ₂ O ₃ into the core.

When the total content of RE ¹ ₂ O ₃ and RE ² ₂ O ₃ exceeds the content of RE ³ ₂ O ₃ , grain growth is likely to occur, and IR life and capacity-temperature characteristics deteriorate.

When the total amount of RE ¹ ₂ O ₃ , RE ² ₂ O _3, and RE ³ ₂ O ₃ is less than 0.30 mol with respect to 100 mol of the main component, there is no effect in improving the IR life, and when it exceeds 1.50 mol Sinterability tends to decrease and the firing temperature tends to increase. In addition, the relative permittivity tends to decrease, and the IR life and CR product tend to deteriorate.

BaZrO ₃ has the effect of improving the relative dielectric constant, dielectric loss, and capacitance-temperature characteristics. By the above-mentioned Gd is solid solution in BaTiO ₃ in particles, Zr in BaZrO ₃ is not diffused to the inside BaTiO ₃ particles tend to form a shell layer containing Zr in an outer portion of the BaTiO ₃ particles . As a result, the above effects can be exhibited.
In the present embodiment, it is preferred to use as a subcomponent material in the form of BaZrO ₃ is a composite oxide. If it is simply used as an auxiliary component material in the form of BaO and ZrO ₂ , Zr will diffuse too much into the BaTiO ₃ particles, and the characteristics such as IR lifetime will deteriorate.
BaZrO ₃ is 0.20 to 1.0 mol, preferably 0.20 to 0.70 mol, more preferably 0.20 to 0.50 mol in terms of BaZrO _{3 with} respect to 100 mol of the main component. Included. When the content of BaZrO ₃ is too small, the relative dielectric constant decreases and the insulation resistance (IR) and the IR lifetime tend to deteriorate. On the other hand, when the content of BaZrO ₃ is too large, the capacity-temperature characteristics and the DC bias characteristics tend to deteriorate. Note that BaZrO ₃ is detected not as BaZrO ₃ but as Zr after sintering.

An oxide of an element selected from the group consisting of V, Ta, Mo, Nb, and W has an effect of improving the IR life. Among these oxides, V oxides, particularly V ₂ O ₅ are preferably used. The oxides of V, Ta, Mo, Nb, and W are each 0.05 to 100 mol in terms of V ₂ O ₅ , Ta ₂ O ₅ , MoO ₃ , Nb ₂ O ₅ , and WO _{3 with} respect to 100 mol of the main component. It is included in an amount of 0.25 mol, preferably 0.05 to 0.20 mol, more preferably 0.05 to 0.15 mol. When the content of these oxides is too small, the effect of improving the reliability (IR life) cannot be obtained. Moreover, when there is too much content of these oxides, it exists in the tendency for an insulation resistance to fall large.

In this embodiment, it is preferable that the dielectric ceramic composition of the present invention further includes a sintering aid. As a sintering aid to be contained, various compounds that act as a sintering aid can be used. Examples of such a compound include SiO ₂ , Li ₂ O and B ₂ O _{3. In} the present invention, it is preferable to use SiO ₂ . The sintering aid is preferably 0.40 mol to 2.0 mol, more preferably 0.40 to 1.75 mol, still more preferably 0.40 to 1.50 mol with respect to 100 mol of the main component. Included in quantity. If the content of the sintering aid is too small, the dielectric magnetic composition will be insufficiently sintered, the relative dielectric constant will decrease, and the insulation resistance, breakdown voltage and IR life will tend to decrease greatly. is there. On the other hand, if the content of the sintering aid is too large, the relative dielectric constant tends to decrease.

  Note that in this specification, each oxide or composite oxide constituting the main component and each subcomponent is represented by a stoichiometric composition, but the oxidation state of each oxide or composite oxide is the stoichiometric composition. It may be out of the range. However, the said ratio of each subcomponent is calculated | required by converting into the oxide or composite oxide of the said stoichiometric composition from the metal amount contained in the oxide or composite oxide which comprises each subcomponent.

The thickness of the dielectric layer 2 is not particularly limited, but is preferably 2.0 μm or less per layer, more preferably 1.0 μm or less. Although the minimum of thickness is not specifically limited, For example, it is about 0.5 micrometer. According to the dielectric ceramic composition of the present invention, even when the interlayer thickness is 0.5 to 2.0 μm, the relative dielectric constant is 3500 or more, and under a high electric field strength (4 V / μm). The CR product is 1500 Ω · F or higher at 20 ° C and the breakdown voltage is extremely high at 100 V / μm or higher, so that the rate of decrease in capacitance when applied at 2 V / μm is 35% or less and 10 V / μm at 150 ° C. It is possible to form a dielectric layer in which the time until the insulation resistance reaches 10 ⁴ Ω in an accelerated life test with voltage applied is 5 hours or more.

  The number of laminated dielectric layers 2 is not particularly limited, but is preferably 200 or more, more preferably 400 or more.

  The average crystal grain size of the dielectric particles contained in the dielectric layer 2 is not particularly limited, and may be appropriately determined from the range of 0.1 to 0.5 μm, for example, according to the thickness of the dielectric layer 2 and the like. The thickness is preferably 0.2 to 0.3 μm. Note that the average crystal grain size of the dielectric particles contained in the dielectric layer is measured as follows. First, the obtained capacitor sample is cut along a surface perpendicular to the internal electrode, and the cut surface is polished. Then, the polished surface is subjected to chemical etching, followed by observation with a scanning electron microscope (SEM), and calculation is performed assuming that the shape of the dielectric particles is a sphere by the code method.

  The conductive material contained in the internal electrode layer 3 is not particularly limited, but a base metal can be used because the constituent material of the dielectric layer 2 has reduction resistance. As the base metal used as the conductive material, Ni or Ni alloy is preferable. The Ni alloy is preferably an alloy of Ni and one or more elements selected from Mn, Cr, Co and Al, and the Ni content in the alloy is preferably 95% by weight or more.

  The conductive material contained in the external electrode 4 is not particularly limited, but in the present invention, inexpensive Ni, Cu, and alloys thereof can be used. The thickness of the external electrode 4 may be determined as appropriate according to the application and the like, but is usually preferably about 10 to 50 μm.

  In the multilayer ceramic capacitor using the dielectric ceramic composition of the present invention, as in the conventional multilayer ceramic capacitor, a green chip is produced by a normal printing method or sheet method using a paste, and this is fired, and then externally It is manufactured by printing or transferring an electrode and firing. Hereinafter, the manufacturing method will be specifically described.

First, a dielectric ceramic composition powder contained in the dielectric layer paste is prepared.
As shown in FIG. 2, the raw material of the main component and the raw material of the subcomponent are mixed by a ball mill or the like to obtain a dielectric ceramic composition powder.

BaTiO ₃ is used as a main component material. There are no particular restrictions on the method for producing the main component raw material, and a mixture of a precipitate obtained by a coprecipitation method, a sol-gel method, an alkali hydrolysis method, a precipitation mixing method, and the subcomponent raw material is calcined. Also good.

  As the raw material of the auxiliary component, the above-mentioned oxide, a mixture thereof, or a composite oxide can be used. In addition, various compounds that become the above-described oxide or composite oxide by firing, such as carbonates and oxalates. , Nitrates, hydroxides, organometallic compounds, and the like may be selected as appropriate and used as a mixture.

  The method for producing the dielectric ceramic composition powder is not particularly limited. As a method other than the above-described method, when the main component raw material is manufactured, the subcomponent raw material is mixed with the main component starting material. Alternatively, the dielectric ceramic composition powder may be obtained simultaneously with the production of the main component material by the solid phase method or the liquid phase method.

  What is necessary is just to determine content of each compound in the dielectric ceramic composition powder obtained so that it may become a composition of the above-mentioned dielectric ceramic composition after baking.

The average particle diameter of BaTiO _{3 as} the main component material is preferably 0.25 μm or less, more preferably 0.15 to 0.25 μm, in a state before forming a paint. By using such a raw material having a small average particle diameter, the BaTiO ₃ raw material powder contains more stable tetragonal BaTiO ₃ particles than cubic BaTiO ₃ particles. Therefore, the tetragonal nature of the raw material powder is increased, and the ratio c / a, which is the ratio of the c-axis lattice constant to the a-axis lattice constant, can be set to a desired range for the BaTiO ₃ as a whole.
The average particle size of the subcomponent raw material is preferably 0.05 to 0.20 μm, more preferably 0.05 to 0.15 μm. By mixing the main component raw material and the subcomponent raw material, uniform sintering is performed at the time of firing, so that cracking or delamination hardly occurs, and the heat resistance of the element is also improved.

  Further, the lower limit of the particle size distribution of the dielectric ceramic composition powder is preferably 0.05 μm or more, more preferably 0.05 to 0.10 μm, thereby suppressing abnormal grain growth and deteriorating the temperature characteristics of the capacity. Can be prevented. According to the dielectric ceramic composition powder as described above, since the particle size distribution is sharp, a green sheet suitable for a thin layer can be produced, and when the layer thickness is reduced to 0.5 to 2.0 μm. However, stable electrical characteristics can be obtained.

  The average particle size and particle size distribution of the raw material powder is the diameter when the powder is taken with an SEM photograph of 30000 times, the area of an arbitrary 1000 particles is calculated, and it is assumed to be a sphere. The average particle size and particle size distribution can be determined from the calculated diameters.

  The raw materials for the main component and subcomponents may be further calcined. In addition, as calcining conditions, for example, the calcining temperature is preferably 800 to 1100 ° C., and the calcining time is preferably 1 to 4 hours.

  As shown in FIG. 2, the obtained dielectric ceramic composition powder is made into a paint to prepare a dielectric layer paste. The dielectric layer paste may be an organic paint obtained by kneading a dielectric ceramic composition powder and an organic vehicle, or may be a water-based paint.

  An organic vehicle is obtained by dissolving a binder in an organic solvent. The binder used for the organic vehicle is not particularly limited, and may be appropriately selected from usual various binders such as ethyl cellulose and polyvinyl butyral. Further, the organic solvent to be used is not particularly limited, and may be appropriately selected from various organic solvents such as terpineol, butyl carbitol, acetone, toluene, and the like, depending on a method to be used such as a printing method or a sheet method.

  Further, when the dielectric layer paste is used as a water-based paint, a water-based vehicle in which a water-soluble binder or a dispersant is dissolved in water and a dielectric material may be kneaded. The water-soluble binder used for the water-based vehicle is not particularly limited, and for example, polyvinyl alcohol, cellulose, water-soluble acrylic resin, or the like may be used.

  The internal electrode layer paste is made by kneading the above-mentioned organic vehicle with various conductive metals and alloys as described above, or various oxides, organometallic compounds, resinates, etc. that become the above-mentioned conductive materials after firing. Prepare.

  The external electrode paste may be prepared in the same manner as the internal electrode layer paste described above.

  There is no restriction | limiting in particular in content of the organic vehicle in each above-mentioned paste, For example, what is necessary is just about 1-5 weight% of binders, for example, about 10-50 weight% of a solvent. Each paste may contain additives selected from various dispersants, plasticizers, dielectrics, insulators, and the like as necessary. The total content of these is preferably 10% by weight or less.

  When the printing method is used, the dielectric layer paste and the internal electrode layer paste are laminated and printed on a substrate such as PET, cut into a predetermined shape, and then peeled from the substrate to obtain a green chip.

  When the sheet method is used, a dielectric layer paste is used to form a green sheet, the internal electrode layer paste is printed thereon, and these are stacked to form a green chip.

Before firing, the green chip is subjected to binder removal processing. The binder removal treatment may be appropriately determined according to the type of the conductive material in the internal electrode layer paste, but when a base metal such as Ni or Ni alloy is used as the conductive material, the oxygen partial pressure in the binder removal atmosphere is set. It is preferable to be 10 ⁻⁴⁵ to 10 ⁵ Pa. When the oxygen partial pressure is less than the above range, the binder removal effect is lowered. If the oxygen partial pressure exceeds the above range, the internal electrode layer tends to oxidize.

As other binder removal conditions, the temperature rising rate is preferably 5 to 300 ° C./hour, more preferably 10 to 100 ° C./hour, and the holding temperature is preferably 180 to 400 ° C., more preferably 200 to 350. The temperature holding time is preferably 0.5 to 24 hours, more preferably 2 to 20 hours. The firing atmosphere is preferably air or a reducing atmosphere, and as an atmosphere gas in the reducing atmosphere, for example, a mixed gas of N ₂ and H ₂ is preferably used after being humidified.

The atmosphere at the time of green chip firing may be appropriately determined according to the type of conductive material in the internal electrode layer paste, but when a base metal such as Ni or Ni alloy is used as the conductive material, the oxygen content in the firing atmosphere The pressure is preferably 10 ⁻⁹ to 10 ⁻⁴ Pa. When the oxygen partial pressure is less than the above range, the conductive material of the internal electrode layer may be abnormally sintered and may be interrupted. Further, when the oxygen partial pressure exceeds the above range, the internal electrode layer tends to be oxidized.

  Moreover, the holding temperature at the time of baking becomes like this. Preferably it is 1100-1400 degreeC, More preferably, it is 1200-1300 degreeC. In the present invention, since the content of rare earth element oxide as an auxiliary component is relatively small, the firing temperature can be relatively low. If the holding temperature is lower than the above range, the densification becomes insufficient. If the holding temperature is higher than the above range, the electrode temperature is interrupted due to abnormal sintering of the internal electrode layer, the capacity temperature characteristic deteriorates due to diffusion of the constituent material of the internal electrode layer, and the dielectric Reduction of the body porcelain composition is likely to occur.

As other firing conditions, the rate of temperature rise is preferably 50 to 500 ° C./hour, more preferably 200 to 300 ° C./hour, and the temperature holding time is preferably 0.5 to 8 hours, more preferably 1 to 3 hours. The time and cooling rate are preferably 50 to 500 ° C./hour, more preferably 200 to 300 ° C./hour. Also, the firing atmosphere is preferably a reducing atmosphere, as the atmosphere gas, for example, it is preferable to use a wet mixed gas of N ₂ and H _2.

  When firing in a reducing atmosphere, it is preferable to anneal the capacitor element body. Annealing is a process for re-oxidizing the dielectric layer, and this can significantly increase the IR lifetime, thereby improving the reliability.

The oxygen partial pressure in the annealing atmosphere is preferably 10 ⁻³ Pa or more, particularly preferably 10 ^{−2 to} 10 Pa. When the oxygen partial pressure is less than the above range, it is difficult to reoxidize the dielectric layer, and when it exceeds the above range, the internal electrode layer tends to be oxidized.

  The holding temperature at the time of annealing is preferably 1100 ° C. or less, particularly 500 to 1100 ° C. When the holding temperature is lower than the above range, the dielectric layer is not sufficiently oxidized, so that the IR is low and the IR life tends to be short. On the other hand, if the holding temperature exceeds the above range, not only the internal electrode layer is oxidized and the capacity is lowered, but the internal electrode layer reacts with the dielectric substrate, the capacity temperature characteristic is deteriorated, the IR is lowered, the IR Life is likely to decrease. Note that annealing may be composed of only a temperature raising process and a temperature lowering process. That is, the temperature holding time may be zero. In this case, the holding temperature is synonymous with the maximum temperature.

As other annealing conditions, the temperature holding time is preferably 0 to 20 hours, more preferably 2 to 10 hours, and the cooling rate is preferably 50 to 500 ° C./hour, more preferably 100 to 300 ° C./hour. . Further, as the annealing atmosphere gas, for example, humidified N ₂ gas or the like is preferably used.

In the above-described binder removal processing, firing and annealing, for example, a wetter or the like may be used to wet the N ₂ gas or mixed gas. In this case, the water temperature is preferably about 5 to 75 ° C.

  The binder removal treatment, firing and annealing may be performed continuously or independently.

The capacitor element body obtained as described above is subjected to end surface polishing, for example, by barrel polishing or sand blasting, and the external electrode paste is printed or transferred and baked to form the external electrode 4. The firing conditions of the external electrode paste are preferably, for example, about 10 minutes to 1 hour at 600 to 800 ° C. in a humidified mixed gas of N ₂ and H ₂ . Then, if necessary, a coating layer is formed on the surface of the external electrode 4 by plating or the like.

  The multilayer ceramic capacitor of the present invention thus manufactured is mounted on a printed circuit board by soldering or the like and used for various electronic devices.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the embodiment mentioned above at all, and can be variously modified within the range which does not deviate from the summary of this invention.

  For example, in the above-described embodiment, the multilayer ceramic capacitor is exemplified as the electronic component according to the present invention. However, the electronic component according to the present invention is not limited to the multilayer ceramic capacitor, and is composed of a dielectric ceramic composition having the above composition. Any material having a dielectric layer can be used.

Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.
In the following examples and comparative examples, various physical properties were evaluated as follows.

(Relative permittivity ε)
A capacitor sample was measured at a reference temperature of 20 ° C. using a digital LCR meter (YHP4274A manufactured by Yokogawa Electric Corporation) at a frequency of 120 Hz and an input signal level (measurement voltage) of 0.5 Vrms / μm. The capacity C was measured. The relative dielectric constant (no unit) was calculated from the obtained capacitance, the dielectric thickness of the multilayer ceramic capacitor, and the overlapping area of the internal electrodes. A higher dielectric constant is preferable.

(CR product)
The insulation resistance IR after applying a DC voltage of 5 V / μm to the capacitor sample for 1 minute at 20 ° C. was measured using an insulation resistance meter (advantest R8340A). The CR product was measured by determining the product of the capacitance C (unit: μF) measured above and the insulation resistance IR (unit: MΩ).

(Breakdown voltage)
The voltage at which a current of 10 mA or more was applied to the capacitor sample when the voltage was applied was defined as the breakdown voltage. The number of measurements was 50 for each composition, and the central value was the representative value.

(Capacitance temperature characteristics)
It was examined whether the temperature characteristics of the capacitance satisfied EIA standards X5R and X6S. Specifically, for X5R, the capacity is measured with a LCR meter at a measurement voltage of 0.5 Vrms at a temperature of −55 to 85 ° C., and whether the capacity change rate is within ± 15% (reference temperature 25 ° C.). I investigated.
For X6S, the capacity was measured with an LCR meter at a measurement voltage of 0.5 Vrms at a temperature of −55 to 105 ° C., and it was examined whether the capacity change rate was within ± 22% (reference temperature 25 ° C.).

(DC bias characteristics)
First, after measuring the electrostatic capacity when an AC voltage of 120 Hz and 0.5 Vrms was applied, the electrostatic capacity when an AC voltage of DC 2.0 V (2 V / μm) and 120 Hz and 0.5 Vrms were applied simultaneously Was measured. The rate of decrease in capacitance was calculated from the measured values obtained.

(IR life test)
As an accelerated life test, a DC voltage of 10 V (10 V / μm) was applied at a temperature of 150 ° C., and the change over time in the insulation resistance was measured. In the accelerated life test, the time when the insulation resistance (IR) value of each sample was 10 ⁴ Ω or less was defined as the IR life time, and the average life time for a plurality of samples was obtained.

Example 1
BaTiO ₃ as the main component material, and MgO, MnO, RE ¹ ₂ O ₃ , RE ² ₂ O ₃ and RE ³ ₂ O ₃ as the subcomponent material, oxides of any of the respective elements A dielectric slurry was prepared by preparing an oxide of an element selected from the group consisting of BaZrO ₃ , V, Ta, Mo, Nb, and W, and SiO ₂ as a sintering aid. The BaTiO _{3 used} was Ba / Ti of 1.000 and c / a of 1.0098. Also selected from oxides of any of the elements selected from MgO, MnO, RE ¹ ₂ O ₃ , RE ² ₂ O ₃ and RE ³ ₂ O ₃ , BaZrO ₃ , V, Ta, Mo, Nb, and W As the oxide of the element selected from the group, a previously calcined material was used.

The composition of the prepared dielectric material is shown in Tables 1-3. The content of the subcomponent main component (BaTiO ₃₎ is the amount for 100 moles. In sample numbers 1 to 5, Ba / Ti was changed. In sample numbers 6 to 9, c / a was changed. In sample numbers 10 to 16, the content of the minor component MgO was changed. In sample numbers 17 to 23, the content of MnO was changed.

In sample numbers 24-28, the content of BaZrO ₃ was changed. In sample numbers 29 to 34, the content of V ₂ O ₅ was changed, and in sample numbers 35 to 38, V was changed to Ta, Mo, Nb, and W. In sample numbers 39 to 44, the content of SiO ₂ was changed.

In sample numbers 45 to 52, RE ¹ ₂ O ₃ ≧ RE ² ₂ O ₃ is set, and in sample numbers 53 to 57, (RE ¹ ₂ O ₃ + RE ² ₂ O ₃ )> RE ³ ₂ O ₃ is set and sample number 58 is set. Then, (RE ¹ ₂ O ₃ + RE ² ₂ O ₃ + RE ³ ₂ O ₃ ) <0.3, and in sample numbers 59 to 64, 0.3 ≦ (RE ¹ ₂ O ₃ + RE ² ₂ O ₃ + RE ³ ₂ O ₃ ) ≦ 1.5, and in the sample number 65, (RE ¹ ₂ O ₃ + RE ² ₂ O ₃ + RE ³ ₂ O ₃ )> 0.3.

In sample numbers 66 to 69, the contents of RE ¹ ₂ O ₃ , RE ² ₂ O ₃ , and RE ³ ₂ O ₃ were not changed, and only the elements were changed. Samples marked with “*” in the table represent comparative examples of the present invention. In addition, numerical values represented by italics in the table indicate numerical values that are outside the scope of the present invention.

  Then, using the dielectric slurry obtained as described above, a green sheet having a thickness of 1.2 μm is formed on a PET film, and an internal electrode paste is formed on the green sheet by 1.0 μm. The green sheet which printed by thickness and has an electrode layer was manufactured.

  As the internal electrode paste, a paste formed using Ni particles and an organic vehicle was used.

  Next, a plurality of green sheets having electrode layers were laminated and pressure-bonded to obtain a green laminated body, and the green laminated body was cut into a predetermined size to obtain a green chip.

  Next, the obtained green chip was subjected to binder removal treatment, firing and annealing under the following conditions to obtain a multilayer ceramic fired body.

The binder removal treatment conditions were temperature rising rate: 60 ° C./hour, holding temperature: 300 ° C., temperature holding time: 8 hours, and atmosphere: in the air.
Firing conditions are: temperature rising rate: 200 ° C./hour, holding temperature: 1150 ° C. to 1250 ° C., temperature holding time: 2 hours, cooling rate: 300 ° C./hour, atmosphere: mixed gas of humidified N ₂ and H ₂ It was.
The annealing conditions were: holding temperature: 1000 to 1100 ° C., temperature holding time: 2 hours, temperature increase, temperature decreasing rate: 200 ° C./hour, atmosphere: humidified N ₂ gas.

  Next, after polishing the end face of the obtained multilayer ceramic fired body by sand blasting, In-Ga was applied as an external electrode to obtain a sample of the multilayer ceramic capacitor shown in FIG. The size of the obtained capacitor sample is 2.0 × 1.25 × 1.25 mm, the thickness and number of layers of the dielectric layer are 1.0 μm × 100 layers, and the thickness of the internal electrode layer is about 0.2 mm. It was 8 μm.

  The characteristics described above were evaluated for each sample. The results are shown in Tables 3-5. In addition, numerical values represented in italics in the table indicate numerical values that are outside the range of the object physical properties of the present invention.

  As shown in Tables 3-5, by setting the composition of the dielectric material within the range specified in the present application, the dielectric constant ε, CR product, breakdown voltage, capacitance temperature characteristics, DC bias characteristics, IR life test An excellent capacitor can be obtained. On the other hand, if the composition is out of the predetermined composition range, any of the above physical property values does not satisfy the target value.

FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention. FIG. 2 is a flowchart showing a manufacturing process of the multilayer ceramic capacitor according to one embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor 10 ... Capacitor element main body 2 ... Dielectric layer 3 ... Internal electrode layer 4 ... External electrode

Claims (7)

BaTiO ₃ as a main component,
For 100 mol of the main component, as an auxiliary component, in terms of each oxide or composite oxide,
MgO: 0.50 to 3.0 mol,
MnO: 0.05 to 0.5 mol,
Sm, Eu, oxide of an element selected from the group consisting of ^{_{Gd (RE 1 2 O 3)}} ,
An oxide (RE ² ₂ O ₃ ) of an element selected from the group consisting of Tb and Dy,
An oxide (RE ³ ₂ O ₃ ) of an element selected from the group consisting of Y, Ho, Er, Yb, Tm, and Lu,
BaZrO ₃ : 0.20 to 1.0 mol, and an oxide of an element selected from the group consisting of V, Ta, Mo, Nb, and W: 0.05 to 0.25 mol,
The content of RE ¹ ₂ O ₃ , RE ² ₂ O ₃ and RE ³ ₂ O ₃ is
RE ¹ ₂ O ₃ <RE ² ₂ O ₃ and (RE ¹ ₂ O ₃ + RE ² ₂ O ₃ ) ≦ RE ³ ₂ O ₃
A dielectric ceramic composition satisfying The content of RE ¹ ₂ O ₃ , RE ² ₂ O ₃ and RE ³ ₂ O ₃ with respect to 100 mol of the main component is
The dielectric ceramic composition according to claim 1, wherein 0.30 mol ≦ (RE ¹ ₂ O ₃ + RE ² ₂ O ₃ + RE ³ ₂ O ₃ ) ≦ 1.50 mol is satisfied.   The dielectric ceramic composition according to claim 1 or 2, further comprising 0.40 to 2.0 mol of a sintering aid as a subcomponent with respect to 100 mol of the main component. The RE ¹ is Gd;
The RE ² is Dy;
The dielectric ceramic composition according to claim 1, wherein RE ³ is Y. The dielectric ceramic composition according to claim 1, wherein Ba / Ti indicating a molar ratio of Ba and Ti in the BaTiO ₃ is 0.997 to 1.003. 6. The dielectric ceramic composition according to claim 1, wherein c / a indicating a ratio of a c-axis lattice constant to an a-axis lattice constant in the crystal lattice of BaTiO ₃ is 1.0095 or more. .   The electronic component which has a dielectric material layer comprised with the dielectric material ceramic composition in any one of Claims 1-6, and an internal electrode layer.

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