JP2008285373A - Dielectric ceramic composition and electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric ceramic composition having high dielectric constant and excellent temperature characteristic of capacitance. <P>SOLUTION: The dielectric ceramic composition contains a first main component represented by formula: (Ba<SB>1-x</SB>Ca<SB>x</SB>)(Ti<SB>1-y</SB>Zr<SB>y</SB>)O<SB>3</SB>(where, 0.04≤x≤0.08, 0.08≤y≤0.18) and a second main component represented by formula: (Ba<SB>1-z</SB>Ca<SB>z</SB>)TiO<SB>3</SB>(where 0≤z≤0.04) in the quantity of 30-60 mol first main component and 40-70 mol second main component per 100 mol in total of the first main component and the second main component and further contains, as accessary components and expressed in terms of oxide, 0.05-0.75 mol MnO, 0.25-1.50 mol Re<SB>2</SB>O<SB>3</SB>(where, Re is a rare earth element), 0.02-0.15 mol oxide of element selected from a group of V, Ta, Mo, Nb and W and 0.3-0.15 mol sintering aid. <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. The dielectric material used to form the dielectric layer of a multilayer ceramic capacitor is required to have a high relative dielectric constant for miniaturization and high capacity, as well as low dielectric loss and dielectric properties. Various characteristics such as low dependency on temperature (temperature dependency) and low dependency on DC voltage (DC bias dependency) are required.

  As such a dielectric ceramic composition, for example, Patent Document 1 contains “perovskite-type barium titanate crystal particles (BCT-type crystal particles) in which part of the A site is substituted with Ca, and substituted Ca”. Dielectric porcelain having no perovskite-type barium titanate crystal particles (BT-type crystal particles), the surface of the BT-type crystal particles being coated with a composite oxide containing an alkaline earth element, a rare earth element and Si A “dielectric porcelain characterized in that a layer is formed” is disclosed.

In the dielectric ceramic of Patent Document 1, the relative dielectric constant is 2000 or more, the temperature characteristic of the relative dielectric constant is within ± 10%, and the change rate of the relative dielectric constant by applying a DC bias of 2 V / μm is within 20%. Is achieved.
JP 2003-40671 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, not only the improvement of the dielectric material but also the measures to increase the number of layers by reducing the thickness of the dielectric layer and to increase the electrode area by making the margin as small as possible. In many cases, however, the difficulty in reliability, such as the deterioration of the insulation resistance of the dielectric ceramic composition over time, makes it difficult to reduce the thickness. 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. With conventional materials, reliability (insulation degradation) and capacity reduction due to DC bias voltage have been problems. For this reason, it has been necessary to develop a dielectric material having a relative dielectric constant that can withstand the high electric field strength due to the thinning and increase the layer thickness that affects the DC bias characteristics. However, as described above, in the dielectric ceramic composition of Patent Document 1, although various characteristics such as the relative dielectric constant and the capacitance temperature characteristic (characteristic against temperature change) have been improved, the relative dielectric constant is 3000 at the maximum. The degree was low and could not fully meet the above requirements. Further, the product of the capacitance and the insulation resistance (CR product) and the IR life when used under a particularly high electric field strength are not necessarily sufficient, and further improvement is desired.

The present invention has been proposed in order to solve the above-described problems of the prior art. The object of the present invention is to show a relative dielectric constant of 5000 or more at a layer thickness of 1 to 5 μm and a high electric field strength (4 V / In the accelerated life test, the product of capacitance and insulation resistance (CR product) is 4000 Ω · F or higher at 20 ° C and 18 V / μm at 180 ° C. Time to reach 10 ⁵ Ω is as long as 10 hours or more, the withstand voltage is 70 V / μm or more, the rate of decrease in capacitance when applied at 2 V / μm is 60% or less, and a base metal such as Ni It is an object of the present invention to provide a dielectric magnetic composition capable of firing in a reducing atmosphere that can be suitably used for a multilayer ceramic capacitor having an internal electrode. Another object of the present invention is to provide an electronic component such as a highly reliable multilayer ceramic capacitor in which the temperature characteristic of capacitance satisfies the X6S characteristic defined by the EIA standard.

  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, this invention which solves the said subject contains the following matter as a summary.

(1) The first main component is a composition formula: (Ba _1-x Ca _x ) (Ti _1-y Zr _y ) O ₃ (where 0.04 ≦ x ≦ 0.08, 0.08 ≦ y ≦ 0. represented by 18), the second principal component is a composition _{formula: (Ba 1-z Ca z} ) TiO 3 ( provided that, 0 ≦ z represented by ≦ 0.04), the first and second principal components For a total of 100 moles
30-60 mol of the first main component, 40-70 mol of the second main component, and as an auxiliary component, in terms of each oxide,
MnO: 0.05 to 0.75 mol,
Re ₂ O ₃ (where Re is a rare earth element): 0.25 to 1.50 mol,
Oxides of elements selected from the group consisting of V, Ta, Mo, Nb, and W: 0.02 to 0.15 mol, and sintering aids: 0.3 to 2.0 mol,
A dielectric ceramic composition comprising:

(2) The dielectric ceramic composition according to (1), wherein the sintering aid contains SiO ₂ .

(3) An electronic component having a dielectric layer made of the dielectric ceramic composition according to (1) or (2) and an internal electrode layer.

  According to the dielectric ceramic composition of the present invention, even when the layer thickness is 1 to 5 μm, while maintaining good CR product, IR life, breakdown voltage, DC bias characteristics, and capacity-temperature characteristics, a high relative dielectric constant (for example, 5000 or more) can be realized. Moreover, the dielectric ceramic composition of the present invention maintains the above characteristics even when it is used at a high electric field strength (4 V / μm). Furthermore, according to the dielectric ceramic composition of the present invention, it is possible to achieve a high relative dielectric constant while satisfying the X6S characteristic defined by the EIA standard for the capacitance-temperature characteristic.

  Therefore, in an electronic component having a dielectric layer composed of the above dielectric ceramic composition, particularly a multilayer ceramic capacitor, high reliability is guaranteed even under severe usage environment due to the excellent capacitance-temperature characteristics of the dielectric. .

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 respective 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 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 a first main component having a composition represented by (Ba _1−x Ca _x ) (Ti _1−y Zr _y ) O ₃ , and (Ba _1−z Ca _z ) TiO _3. And an oxide of an element selected from the group consisting of MnO, rare earth oxide (Re ₂ O ₃ ), V, Ta, Mo, Nb, and W as a secondary component. And a sintering aid. At this time, the amount of oxygen (O) may be slightly deviated from the stoichiometric composition of the above formula.

  The first main component has the effect of increasing the dielectric constant at room temperature. In the above composition formula, x is 0.04 to 0.08, preferably 0.04 to 0.06. Moreover, y is 0.08 to 0.18, preferably 0.08 to 0.15.

  In the above composition formula, x represents the amount of substitution of Ca with respect to Ba. If x is in the above range, the dielectric constant, CR product, and accelerated lifetime of the dielectric are improved. However, if x exceeds 0.08, grain growth is likely to occur and the temperature characteristics of the capacitance are lowered. In addition, the DC bias characteristic may be deteriorated.

  In the above composition formula, y represents the amount of substitution of Zr for Ti. If y is in the above range, the dielectric constant, CR product, and accelerated life of the dielectric are improved. However, if y exceeds 0.18, the temperature characteristics of the capacitor may be lowered.

  Furthermore, in the first main component, the ratio [Ba + Ca] / [Ti + Zr] of the total number of moles of Ba and Ca [Ba + Ca] to the total number of moles of Ti and Zr [Ti + Zr] is preferably 0.00. It is desirable that it is 995 to 1.010, more preferably about 1.000. When [Ba + Ca] / [Ti + Zr] is less than 0.995, abnormal grain growth of the dielectric layer tends to occur during firing, and the capacity-temperature characteristics and DC bias characteristics tend to deteriorate. Sinterability tends to decrease and the firing temperature tends to increase, which may cause structural defects (delamination and cracks).

  The second main component has an effect of flattening the capacity-temperature characteristic. In the above composition formula, z is 0 to 0.04, preferably 0 to 0.03.

  In the above composition formula, z represents the amount of substitution of Ca with respect to Ba. If z is in the above range, the dielectric constant, CR product, and accelerated lifetime of the dielectric are improved. However, if z exceeds 0.04, grain growth is likely to occur and the temperature characteristics of the capacitance are lowered. In addition, the DC bias characteristic may be deteriorated.

  Further, in the second main component, the ratio of the total number of moles of Ba and Ca [Ba + Ca] to the number of moles of Ti [Ti], [Ba + Ca] / [Ti] is preferably 0.995 to 1 .010, more preferably about 1.000. If [Ba + Ca] / [Ti] is less than 0.995, abnormal grain growth of the dielectric layer tends to occur during firing, and the capacity-temperature characteristics and DC bias characteristics tend to deteriorate. Sinterability tends to decrease and the firing temperature tends to increase, which may cause structural defects (delamination and cracks).

  The dielectric ceramic composition of the present invention has a first main component of 30 to 60 mol, preferably 40 to 60 mol, and a second main component with respect to a total of 100 mol of the first main component and the second main component. It contains 40 to 70 mol, preferably 40 to 60 mol. If the blending amount of the first main component and the second main component is out of the above range, target physical properties such as relative dielectric constant (5000 or more) and capacity-temperature characteristic (X6S) are not satisfied.

  In the dielectric ceramic composition of the present invention, the first main component and the second main component may partially form a solid solution phase, but the crystal phase inherent to each component is almost the same. Maintained and confirmed by X-ray diffraction analysis or the like.

The dielectric ceramic composition according to the present invention includes, as subcomponents, oxides of elements selected from the group consisting of MnO, rare earth oxides (Re ₂ O ₃ ), V, Ta, Mo, Nb, and W, and firing. Contains a caustic agent.

  MnO has the effect of promoting sintering, the effect of increasing the insulation resistance IR, and the effect of improving the IR lifetime, and 0.050 to 0.750 mol in terms of MnO with respect to 100 mol of the main component. , Preferably 0.100 to 0.600 mol, more preferably 0.150 to 0.500 mol. When the MnO content is less than 0.050 mol, the CR product and the IR lifetime are lowered. Moreover, when the content of MnO exceeds 0.750 mol, the relative permittivity tends to decrease.

The rare earth oxide (Re ₂ O ₃ ) is not particularly limited and may be oxides of various rare earth elements, but preferably Y, Eu, Gd, Tb, Dy, Ho, Er, Tm or It is preferably at least one oxide of each element of Yb, more preferably at least one oxide of each element of Y, Gd, Er, or Ho. These rare earth elements may be used alone or in combination, and the same effect can be obtained. The rare earth oxide is 0.25 to 1.50 mol, preferably 0.25 to 1.25 mol, more preferably 0.30 to 1.00 in terms of Re ₂ O _{3 with} respect to 100 mol of the main component. Contained in molar amounts. When the content of the rare earth element oxide is less than 0.25 mol, the IR lifetime is lowered. On the other hand, if the rare earth oxide content exceeds 1.50 mol, the sinterability tends to decrease, the firing temperature tends to increase, and it becomes difficult to obtain a sufficient dielectric constant.

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 0.02 to 100 mol in terms of V ₂ O ₅ , Ta ₂ O ₅ , MoO ₃ , Nb ₂ O ₅ , and WO ₃ , respectively. It is included in an amount of 0.15 mol, preferably 0.03 to 0.12 mol, more preferably 0.04 to 0.10 mol. When the content of these oxides is less than 0.02 mol, the capacity-temperature characteristic (X6S) is not satisfied. Moreover, when the content of these oxides exceeds 0.15 mol, the insulation resistance tends to be greatly reduced.

As a sintering aid contained in the dielectric ceramic composition of the present invention, various compounds that act as a sintering aid can be used. Examples of such a compound include SiO ₂ , MO (where M is at least one element selected from Ba, Ca, Sr and Mg), Li ₂ O and B ₂ O ₃ . In addition, a compound that is a composite oxide of SiO ₂ , BaO, and CaO, that is, a compound represented by a composition formula (Ba _1-z Ca _z ) SiO ₃ can be used. In the present invention, among these sintering aids, those containing SiO ₂ are particularly preferable. The sintering aid is included in an amount of 0.3 to 2.0 mol, preferably 0.5 to 2.0 mol, more preferably 0.75 to 1.75 mol, relative to 100 mol of the main component. . If the content of the sintering aid is less than 0.3 mol, the dielectric magnetic composition is not sufficiently sintered, the relative permittivity is lowered, and the CR product, insulation resistance and IR life are greatly reduced. Tend to. On the other hand, when the content of the sintering aid exceeds 3.0 mol, the relative dielectric constant is lowered.

Moreover, you may add another subcomponent in the range which can achieve the objective of this invention.
An example of an auxiliary component that may be added is MgO. MgO has the effect of flattening the capacity-temperature characteristics. When adding MgO, it is used in an amount of 0.50 mol or less, preferably 0.03 to 0.30 mol, more preferably 0.05 to 0.25 mol, relative to 100 mol of the main component. . However, in the dielectric ceramic composition of the present invention, if the content of MgO is too large, the capacity-temperature characteristic is adversely deteriorated. Therefore, the addition amount is preferably 0.50 mol or less.

  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 5 μm or less per layer, more preferably 3 μm or less. Although the minimum of thickness is not specifically limited, For example, it is about 1 micrometer. According to the dielectric ceramic composition of the present invention, the dielectric constant is 5000 or more when the layer thickness is 1 μm or more, and the capacitance resistance product under high electric field strength (4 V / μm) is 4000 Ω · F or more at 20 ° C. Is very high at 70 V / μm or more, and the degradation rate of the insulation resistance in the accelerated life test in which the voltage decrease rate is 18 V / μm at 180 ° C. is 60% or less when 2 V / μm is applied. It is possible to form a dielectric layer that takes 10 hours or more to reach.

  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 1.0 to 5.0 μm, for example, according to the thickness of the dielectric layer 2 and the like. The thickness is preferably 2.0 to 3.0 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.

  As the raw material of the main component, the first main component and the second main component are used. 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 size of the first main component and the second main component is preferably 0.05 to 1.0 μm, more preferably 0.05 to 0.50 μm in the state before coating, and the subcomponent raw material The average particle size of is preferably 0.05 to 0.20 μm, more preferably 0.05 to 0.15 μm. By mixing the main component material and subcomponent material having such a particle size, uniform sintering is performed at the time of firing, so that cracks or delamination hardly occurs, and the heat resistance of the device 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 stable even when the layer thickness is reduced to 1 to 5 μm. 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. Calculate and determine the average particle size and particle size distribution from the diameters obtained.

  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 prepared 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 binders. 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 using the printing method, 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 off 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. 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 internal electrode layer constituent material, 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. Further, the firing atmosphere is preferably a reducing atmosphere, and as the atmosphere gas, for example, a mixed gas of N ₂ and H ₂ is preferably used by humidification.

  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 was 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).

(Pressure resistance)
A voltage with a voltage of 10 mA or more applied to the capacitor sample when the voltage was applied was defined as a withstand 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 standard X6S. Specifically, the LCR meter was used to measure the capacity at a measurement voltage of 0.5 Vrms at a temperature of −55 to 85 ° C., and examined whether the capacity change rate was within ± 22% (reference temperature 25 ° C.). . Tables 3 and 4 show “A” when satisfied and “C” when not satisfied.

(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 18 V (18 V / μm) was applied at a temperature of 180 ° C., and the change over time in the insulation resistance was measured. In the accelerated life test, the time when the insulation resistance value of each sample was 10 ⁵ Ω or less was defined as the IR life time, and the average life time for a plurality of samples was obtained.

Example 1
As the main component _{material, (Ba 1-x Ca x} ) (Ti 1-y Zr y) O 3 and _{(Ba 1-z Ca z)} TiO 3, as subcomponent _materials, MnO, Re _{2 O} 3, Dielectric slurry was prepared by preparing oxides of elements selected from the group consisting of V, Ta, Mo, Nb, and W, and silica as a sintering aid. Note that an oxide of an element selected from the group consisting of MnO, Re ₂ O ₃ , V, Ta, Mo, Nb, and W was previously calcined.

The composition of the prepared dielectric material is shown in Tables 1 and 2. In Sample Nos. 1 to 12, the composition (x, y) and the blending amount of (Ba _1-x Ca _x ) (Ti _1-y Zr _y ) O ₃ as the first main component were changed. Sample No. 13 to 19, was changed to a second principal component _{(Ba 1-z} Ca z) composition of TiO ₃ (z) and the amount. In sample numbers 20-24, the compounding quantity of MnO was changed. In sample numbers 25 to 39, the blending amount and type of rare earth oxides (Ho ₂ O ₃ , Y ₂ O ₃ , Er ₂ O ₃ , Gd ₂ O ₃ , Dy ₂ O ₃ , Yb ₂ O ₃ ) were changed. In sample numbers 40-47, the compounding quantity and kind of the oxide of the element chosen from the group which consists of V, Ta, Mo, Nb, and W were changed. In sample numbers 48 to 52, the blending amount of the sintering aid (silica) was changed. Sample No. 53 uses (Ba _1−x Ca _x ) (Ti _1−y Zr _y ) O ₃ containing Ba, Ca, Ti, and Zr which are the same as the total composition of the first and second main components in Sample No. 34. It was. 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 predetermined range 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, paste made 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 and 4. 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 and 4, by setting the composition of the dielectric material within the range specified in the present application, the dielectric constant ε, CR product, withstand voltage, capacitance temperature characteristics, DC bias characteristics, and IR life test are excellent. Capacitor is 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. Further, from the comparison with the sample numbers 34 and 53, even if BCTZ having the same composition as the total composition of the first main component and the second main component is used, the target temperature characteristic is not achieved, and the first main component, second It was shown that it is necessary that each of the main components exist independently without completely dissolving.

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 (3)

The first main component is represented by the composition formula: (Ba _1−x Ca _x ) (Ti _1−y Zr _y ) O ₃ (where 0.04 ≦ x ≦ 0.08, 0.08 ≦ y ≦ 0.18). The second main component is represented by the composition formula: (Ba _1-z Ca _z ) TiO ₃ (where 0 ≦ z ≦ 0.04), and the total of the first main component and the second main component is 100 mol. Whereas
30-60 mol of the first main component, 40-70 mol of the second main component, and as an auxiliary component in terms of each oxide,
MnO: 0.05 to 0.75 mol,
Re ₂ O ₃ (where Re is a rare earth element): 0.25 to 1.50 mol,
Oxides of elements selected from the group consisting of V, Ta, Mo, Nb, and W: 0.02 to 0.15 mol, and sintering aids: 0.3 to 2.0 mol,
A dielectric ceramic composition comprising: The dielectric ceramic composition according to claim 1, wherein the sintering aid contains SiO ₂ .   An electronic component comprising a dielectric layer made of the dielectric ceramic composition according to claim 1 and an internal electrode layer.

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