JP2006117483A - Method for producing dielectric ceramic composition, and electronic component and multilayer ceramic capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a dielectric ceramic composition composed of fine particles and used for a dielectric layer of a multilayer ceramic capacitor, which has good electric properties (e.g. high dielectric constant, CR product, IR life, etc.) and temperature characteristics (e.g. satisfying X5R or the like). <P>SOLUTION: This method for producing the dielectric ceramic composition comprising barium titanate, a glass component and an additive component is characterized by using a barium titanate raw material in which a (111) plane diffraction peak is observed in an X-ray diffraction using Cu-Kα beam as the X-ray source, and the half-value width of the diffraction peak is controlled to be 0.2° or less. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a dielectric ceramic composition used as a dielectric layer of an electronic component such as a multilayer ceramic capacitor, a dielectric ceramic composition produced by the method, and a dielectric ceramic composition comprising the dielectric ceramic composition. The present invention relates to an electronic component such as a multilayer ceramic capacitor used as a body layer.

  In recent years, multilayer ceramic capacitors, which are examples of electronic components, have been increasingly reduced in size and capacity, and in order to increase the obtained capacity, the dielectric layer per layer in the multilayer ceramic capacitor is made thinner. Is required.

  However, if the dielectric layer is thinned without taking any measures, the reliability of the multilayer ceramic capacitor decreases as the electric field strength increases, and the short circuit occurs frequently, resulting in poor yield. Tend.

  As one solution to such a problem, a method of miniaturizing the dielectric particles (grains) constituting the dielectric layer can be considered. This is because the dielectric layer is composed of dielectric particles and grain boundaries, so that if the size of the dielectric particles is large, there is a limit to the reduction in thickness. On the other hand, even if the dielectric particles are miniaturized, if the electrical characteristics such as the dielectric constant are poor, the demand from the electronic component market cannot be met.

  Therefore, it is necessary to maintain good electrical characteristics (for example, high dielectric constant, capacitance temperature characteristics, etc.) when the dielectric particles are not only miniaturized but also miniaturized.

  By the way, a multilayer ceramic capacitor is usually manufactured by laminating a paste for an internal electrode layer and a paste for a dielectric layer by a sheet method, a printing method, or the like and integrally firing them. For the conductive material of the internal electrode layer, a relatively inexpensive base metal such as Ni or Ni alloy is used. When a base metal is used as the conductive material for the internal electrode layer, the internal electrode layer is oxidized when fired in the atmosphere. Therefore, it is necessary to perform simultaneous firing of the dielectric layer and the internal electrode layer in a reducing atmosphere. is there. However, when fired in a reducing atmosphere, the dielectric layer is reduced and the specific resistance is lowered. Therefore, a non-reducing dielectric material has been proposed.

  As a non-reducing dielectric material, the current X7R characteristic defined by EIAJ (Japan Electronic Machinery Manufacturers Association) (within a temperature range of −55 ° C. to 125 ° C., the capacitance change rate is ± 15 with respect to 25 ° C.) %) Or X5R characteristics (within a temperature range of −55 ° C. to 85 ° C., the capacitance change rate is within ± 15% based on 25 ° C.), or the B characteristics (−25 to 85 ° C. specified by JIS standards) In the temperature range, those having a satisfactory capacitance temperature stability satisfying a capacitance change rate within ± 10% with respect to 20 ° C. are the mainstream, and various proposals have been made.

  Regarding a dielectric ceramic composition containing barium titanate, which is one of non-reducing dielectric materials, for example, Patent Document 1 discloses a method for obtaining a dielectric ceramic composition in which dielectric particles are miniaturized. Has been proposed. According to the technique described in Patent Document 1, MgO as an additive component raw material is added in an extremely large amount of 7 mol% with respect to the barium titanate raw material. It is considered that the addition of MgO is extremely effective for miniaturization of dielectric particles.

  However, if the amount of MgO added is too large, there may be inconveniences such as deterioration of temperature characteristics and reduction of insulation resistance.

Therefore, it is desired to develop a technique that suppresses as much as possible the amount of additive component raw material that can promote the miniaturization of dielectric particles such as MgO and does not deteriorate the various electrical characteristics described above.
JP 2001-316176 A

  It is an object of the present invention to use as a dielectric layer of a multilayer ceramic capacitor, which does not contain an additive component more than necessary, is composed of fine particles, and has good electrical characteristics even when the capacitor is thinned. (E.g., high dielectric constant, CR product, IR lifetime, etc.) and a method for producing a dielectric ceramic composition having temperature characteristics (e.g., satisfying X5R), a dielectric ceramic composition obtained by the production method, It is an object of the present invention to provide an electronic component such as a multilayer ceramic capacitor that is manufactured using a dielectric ceramic composition, has good electrical characteristics and temperature characteristics, and has high reliability.

In order to achieve the above object, according to the present invention,
A method for producing a dielectric ceramic composition having a barium titanate, a glass component, and an additive component,
In X-ray diffraction using Cu—Kα ray as an X-ray source, a diffraction peak on the (111) plane is observed, and the half width of the diffraction peak (hereinafter sometimes abbreviated as “Δh (111)”) The dielectric ceramic composition is manufactured using a barium titanate raw material having a controlled angle of 0.2 ° or less. A method for manufacturing a dielectric ceramic composition is provided.

Preferably, the barium titanate material has a specific surface area (SSA) measured by a nitrogen adsorption method of 10 to 50 m ² / g.

  By adjusting the SSA of the barium titanate raw material to be used to an appropriate range, there is a tendency that further refinement of the dielectric particles constituting the dielectric ceramic composition after firing is further promoted.

  Preferably, the additive component raw material contains at least an Mg compound, and when the Mg compound is converted to MgO, the ratio with respect to 100 mol of the barium titanate raw material is Mg compound: 2 mol or less (however, 0 mol Except).

  Although it is possible to make the dielectric particles finer by adding the Mg compound, if the MgO addition amount as an additive component is too large as 7 mol% as described in Patent Document 1 described above, the dielectric particles Although miniaturization can be achieved, inconveniences such as deterioration of temperature characteristics and reduction of insulation resistance may occur. Therefore, it is desirable to reduce the amount of MgO added within a range that does not deteriorate such various electrical characteristics.

  In the present invention, even if the addition amount of the Mg compound is small, the dielectric particles can be sufficiently miniaturized. Moreover, since the addition amount can be suppressed, the electrical characteristics are not deteriorated.

Preferably, the additive component raw material further includes
One or both of a Mn compound and a Cr compound;
One or more selected from V compounds, W compounds, Ta compounds and Nb compounds;
R (wherein R is one or more selected from Sc, Er, Tm, Yb, Lu, Y, Dy, Ho, Tb, Gd and Eu),
Mn compound as MnO, Cr compound as Cr ₂ O ₃ , V compound as V ₂ O ₅ , W compound as WO ₃ , Ta compound as Ta ₂ O ₅ , Nb compound as Nb ₂ O ₅ , R The ratio of the above compound to 100 mol of the barium titanate raw material when converted to R ₂ O ₃ is
Mn compound + Cr compound: 0.5 mol or less (excluding 0 mol),
V compound + W compound + Ta compound + Nb compound: 0.5 mol or less (excluding 0 mol),
R compound: 5 mol or less (excluding 0 mol).

Preferably, the glass component raw material contains a Ba compound, a Ca compound and a Si compound,
The Ba compound to BaO, the Ca compound to CaO, the ratio with respect to the barium titanate material 100 mole when converted the Si compound to SiO _2,
Ba compound + Ca compound: 0.5 to 12 mol,
Si compound: 0.5 to 12 mol.

Preferably, the glass component raw material is (Ba _1-x Ca _x ) SiO ₃ (where x = 0.3 to 0.7).

  A particularly preferable method for producing a dielectric ceramic composition according to the present invention is a case that satisfies all the above conditions.

  According to the present invention, a dielectric ceramic composition produced by any one of the above methods is provided.

  The electronic component according to the present invention has a dielectric layer composed of any one of the above dielectric ceramic compositions. 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.

  A multilayer ceramic capacitor according to the present invention has a capacitor element body having a configuration in which dielectric layers composed of any one of the above dielectric ceramic compositions and internal electrode layers are alternately stacked. The conductive material contained in the internal electrode layer is not particularly limited, but is Ni or Ni alloy, for example.

  The present inventors have conducted experiments under the premise that the crystal structure of the barium titanate raw material to be used has some relationship with the grain size of the sintered body after firing. It has been found that there is a correlation, that is, there is a correlation that the dielectric particles constituting the dielectric ceramic composition after firing can be miniaturized or not, depending on the value of the half width of the diffraction peak.

  More specifically, by using a barium titanate raw material in which the half width of the diffraction peak is controlled to a predetermined value or less, compared to the case of using a barium titanate raw material whose half width is not particularly controlled. The dielectric particles (grains) after firing can be miniaturized (for example, the average particle diameter of the dielectric particles can be reduced to 0.26 μm or less). As a result, the dielectric layer can be thinned (for example, the dielectric layer The thickness per layer can be 4.5 μm or less). Moreover, even when the dielectric layer is thinned, such as a multilayer ceramic capacitor having good electrical characteristics (for example, high dielectric constant, CR product, IR lifetime, etc.) and good temperature characteristics (for example, satisfying X5R), etc. An electronic component can be obtained.

  That is, according to the present invention, it is used as a dielectric layer of a multilayer ceramic capacitor, does not contain an additive component more than necessary, is composed of fine particles, and is excellent even when the capacitor is thinned. A method for producing a dielectric ceramic composition having electrical characteristics and temperature characteristics, a dielectric ceramic composition obtained by the production method, and a dielectric ceramic composition produced using the dielectric ceramic composition, having good electrical characteristics and temperature characteristics. It is possible to provide a highly reliable electronic component such as a multilayer ceramic capacitor.

  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 an enlarged cross-sectional view of a main part of the dielectric layer 2 shown in FIG. 3 is an X-ray diffraction chart of a barium titanate raw material at a diffraction angle 2θ = 38.5 to 39.5 °.

  Before describing the method for producing a dielectric ceramic composition according to the present invention, first, a multilayer ceramic capacitor as an example of an electronic component will be described.

Multilayer Ceramic Capacitor As shown in FIG. 1, a multilayer ceramic capacitor 1 as an example of an electronic component of the present invention has a capacitor element body 10 having a configuration in which dielectric layers 2 and internal electrode layers 3 are alternately stacked. A pair of external electrodes 4 are formed at both ends of the capacitor element body 10 so as to be electrically connected to the internal electrode layers 3 arranged alternately in the element body 10. The internal electrode layers 3 are laminated such that the side 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 outer shape and dimensions of the capacitor element body 10 are not particularly limited and can be appropriately set according to the application. Usually, the outer shape is substantially a rectangular parallelepiped shape, and the dimensions are usually vertical (0.4 to 5.6 mm) × It can be about horizontal (0.2-5.0 mm) × height (0.2-1.9 mm).

  The dielectric layer 2 contains a dielectric ceramic composition obtained by the production method of the present invention. The dielectric ceramic composition obtained by the production method of the present invention has barium titanate, a glass component, and an additive component.

Barium titanate is represented by a composition formula (BaO) _m · TiO ₂ , and the molar ratio m in the formula is preferably 0.990 to 1.035.

In this embodiment, the glass component exemplifies a case of containing Ba oxide, Ca oxide, and Si oxide. Preferably, the glass component is represented by (Ba _1-x Ca _x ) SiO ₃ (where x = 0.3 to 0.7).

  In this embodiment, the additive component is selected from Ba oxide, Mg oxide, one or both of Mn oxide and Cr oxide, V oxide, W oxide, Ta oxide, and Nb oxide. One or two or more selected from R and R (wherein R is Sc, Er, Tm, Yb, Lu, Y, Dy, Ho, Tb, Gd and Eu, preferably Y , One or two or more oxides selected from Dy and Ho).

  As shown in FIG. 2, the dielectric ceramic composition constituting the dielectric layer 2 of the present embodiment is composed of a plurality of dielectric particles (grains) 2a and grains formed between a plurality of adjacent dielectric particles 2a. It includes the phase 2b.

  The dielectric particles 2a are mainly composed of the barium titanate described above. The average particle size (= grain size GS) of the dielectric particles 2a is refined to 0.26 μm or less, preferably 0.25 μm or less. By miniaturization, CR product and reliability (IR life) are improved. The lower limit of the average particle diameter is not particularly limited, but is usually about 0.02 μm.

The grain boundary phase 2b is a dielectric material (most of SiO _{2 in} the glass component, a very small part of BaO and CaO, a part of the additive component), an oxide of the material constituting the internal electrode material, or added separately. It is composed mainly of glass or vitreous, and it is composed mainly of oxides of the above materials, and oxides of materials mixed as impurities during the process.

In addition, about Si in the glass component added with respect to barium titanate, it has the property which is hard to be dissolved in the dielectric particle 2a, and is extruded to the grain boundary phase 2b at the time of firing, Most of them are considered to be contained in the grain boundary phase 2b. The grain boundary phase 2b in the present embodiment, Si in the glass component is 0.5 to 20 wt% of in terms of SiO _2, it is contained.

  In the present specification, each oxide constituting the dielectric ceramic composition is represented by a stoichiometric composition, but the oxidation state of each oxide may be out of the stoichiometric composition. However, the ratio of each component is determined by converting the amount of metal contained in the oxide constituting each component into the oxide having the above stoichiometric composition.

  Various conditions such as the number and thickness of the dielectric layers 2 may be appropriately determined according to the purpose and application. In this embodiment, the thickness of the dielectric layer 2 sandwiched between the pair of internal electrode layers 3 is 4 The thickness is reduced to 0.5 μm or less, preferably 3.0 μm or less, more preferably 2.5 μm or less. In the present embodiment, even when the thickness of the dielectric layer 2 is reduced as described above, the CR product and the IR lifetime are improved while maintaining various electrical characteristics of the capacitor 1, particularly sufficient temperature characteristics. .

  The internal electrode layer 3 is preferably made of a base metal conductive material that substantially functions as an electrode. As the base metal used as the conductive material, Ni or Ni alloy is preferable. As the Ni alloy, an alloy of Ni and one or more elements selected from Mn, Cr, Co, Cu and Al is preferable, and the Ni content in the alloy is preferably 95% by weight or more. In addition, in Ni or Ni alloy, various trace components, such as P, may be contained about 0.1 wt% or less. The thickness of the internal electrode layer 3 may be appropriately determined according to the application and the like, but is usually 0.05 to 3 μm, particularly preferably about 0.1 to 2.0 μm.

  The external electrode 4 is usually composed of at least one of Ni, Pd, Ag, Au, Cu, Pt, Rh, Ru, Ir, or an alloy thereof. Usually, Cu, Cu alloy, Ni, Ni alloy, etc., Ag, Ag—Pd alloy, In—Ga alloy, etc. are 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.

Method for Manufacturing Multilayer Ceramic Capacitor Next, an example of a method for manufacturing the multilayer ceramic capacitor 1 according to this embodiment will be described.

  (1) In the present embodiment, the dielectric layer paste that forms the dielectric layer before firing for forming the dielectric layer 2 shown in FIG. 1 after firing, and the internal electrode layer shown in FIG. 1 after firing. The paste for internal electrode layers which will comprise the internal electrode layer before baking for forming 3 is prepared. An external electrode paste is also prepared.

  The dielectric layer paste is prepared by kneading a dielectric material and an organic vehicle.

  (1-1) The dielectric material used in the present embodiment contains each material constituting the above-described dielectric ceramic composition in a predetermined composition ratio. For this reason, first, the barium titanate raw material, the glass component raw material, and the additive component raw material, which are the respective raw materials, are prepared.

Barium titanate raw material The barium titanate raw material has a perovskite type crystal structure represented by ABO ₃ , and has an A / B value (the number of moles of components constituting the A site in the composition formula ABO ₃ , constituting the B site) The value divided by the number of moles of the component to be used) is preferably 0.990 to 1.035, more preferably 0.995 to 1.02, and still more preferably 1.000 to 1.009.

  If the A / B value is too small, grain growth occurs and the high temperature load life (IR life) tends to deteriorate. If the A / B value is too large, the sinterability tends to decrease and firing becomes difficult. It is in.

  The A / B value can be measured by a glass bead method, a fluorescent X-ray analysis method, an ICP method, or the like.

  Examples of the ICP (inductively coupled plasma) method include ICP emission spectroscopy using an ICP emission spectrometer and ICP mass analysis using an ICP mass spectrometer.

  The barium titanate raw material has a perovskite crystal phase as described above, and a diffraction peak on the (111) plane of the perovskite crystal phase is observed in X-ray diffraction. The diffraction peak occurs near the diffraction angle 2θ = 39 ° in the X-ray diffraction chart when Cu—Kα ray is used as the X-ray source.

  In the present invention, by controlling the half-value width of the diffraction peak of the (111) plane, the average particle diameter of the fired dielectric particles 2a can be reduced to 0.25 μm or less. The thickness can be reduced to 4.5 μm or less. Moreover, even when the dielectric layer 2 is thinned, the multilayer ceramic capacitor 1 having good electrical characteristics (for example, high dielectric constant, CR product, IR lifetime, etc.) and good temperature characteristics (for example, satisfying X5R). Can be obtained.

That is, in the present invention, a diffraction peak of (111) plane is observed in X-ray diffraction using Cu—Kα ray as an X-ray source, and the half-value width of the diffraction peak is 0.2 ° or less, preferably 0.8. A barium titanate raw material controlled to 18 ° or less is used. The lower limit of the full width at half maximum is not particularly limited, but is about 0.08 ° from the analysis limit of the X-ray diffractometer.
Note that the half-value width is between two points on the curve that is ½ of the maximum value (diffraction peak) of the curve in the X-ray diffraction chart showing the relationship between the diffraction angle 2θ (horizontal axis) and the intensity (vertical axis). Width is defined as a width parallel to the horizontal axis (unit is “°” or “deg.”).

The value of the half-value width can be controlled by adjusting the size of crystallites constituting the grains and the orientation of crystallites, but the control method is not limited in the present invention.
Note that the measurement conditions in X-ray diffraction are not particularly limited, but in order to obtain a resolution that can confirm the half width, the scan width is usually 0.01 ° or less and the scan speed is 0.1 ° / min or less. As the X-ray detection conditions, the measurement conditions that the parallel slit is 10 mm or less, the diverging slit is 0.3 mm or less, and the light receiving slit is opened are used.

Furthermore, in the present invention, it is desirable to use a barium titanate raw material having a specific surface area (SSA) of 10 to 50 m ² / g, preferably 10 to 45 m ² / g. By adjusting the SSA of the barium titanate raw material to be used to an appropriate range, there is a tendency that further refinement of the dielectric particles 2a after firing is further promoted. If the SSA is too small, it tends to be difficult to miniaturize the dielectric particles 2a after firing. If the SSA is too large, the raw material powder is very fine. It tends to occur and cause a decrease in performance as a capacitor.

  The method for controlling the SSA of the barium titanate raw material is, for example, a method of pulverizing the calcined powder after calcining under appropriate conditions when obtaining a barium titanate raw material by a solid phase method, the temperature of calcining, etc. And a method for controlling the conditions.

The barium titanate raw material used in the present invention can be obtained not only by a so-called solid phase method but also by a so-called liquid phase method. In the case of using BaCO ₃ and CaCO ₃ as starting materials, the solid phase method (calcining method) is a method for obtaining a raw material by weighing, mixing, calcining and pulverizing a predetermined amount thereof. Examples of the liquid phase method include an oxalate method, a hydrothermal synthesis method, an alkoxide method, and a sol-gel method.

Glass component raw material As the glass component raw material, one containing a Ba compound, a Ca compound and a Si compound is used. The Si compound in the glass component raw material acts as a sintering aid, and the Ca compound and the Ba compound have an effect of improving the temperature characteristics of the capacitance (rate of change in capacitance with respect to temperature).

  The glass component raw material used in this embodiment may be in the form of a mixture or in the form of a composite oxide. However, in this embodiment, it is preferable to use in the form of the complex oxide having a melting point lower than that of the mixture.

Examples of the form of the mixture include a Ca compound (such as CaO and CaCO ₃ ) + Si compound (such as SiO ₂ ) + Ba compound (such as BaO and BaCO ₃ ). Examples of the complex oxide include (Ba _1-x Ca _x ) SiO ₃ . X in the above formula is preferably 0.3 to 0.7, and more preferably 0.35 to 0.50. If x is too small, the temperature characteristics tend to deteriorate, and if x is too large, the dielectric constant tends to decrease.

Additive component raw material In the present embodiment, as the additive component raw material,
Mg compound;
One or both of a Mn compound and a Cr compound;
One or more selected from V compounds, W compounds, Ta compounds and Nb compounds;
R (where R is one or more selected from Sc, Er, Tm, Yb, Lu, Y, Dy, Ho, Tb, Gd and Eu, preferably one selected from Y, Dy and Ho) Or two or more compounds).

  The Mg compound has an effect of flattening the capacity-temperature characteristic and an effect of suppressing grain growth. The Mn compound and the Cr compound have an effect of promoting sintering, an effect of increasing IR (insulation resistance), and an effect of improving the high temperature load life. V compound, W compound, Ta compound and Nb compound have the effect of improving the high temperature load life. The compound of R mainly exhibits the effect of improving the high temperature load life.

  The Mg compound means magnesium oxide and / or a compound that becomes magnesium oxide after firing, the Mn compound means manganese oxide and / or the compound that becomes manganese oxide after firing, and the Cr compound means chromium oxide and / or Or the compound which becomes chromium oxide after baking.

  V compound means vanadium oxide and / or a compound which becomes vanadium oxide after firing, W compound means tungsten oxide and / or a compound which becomes tungsten oxide after firing, Ta compound means tantalum oxide and / or fired A compound that later becomes tantalum oxide means an Nb compound, which means niobium oxide and / or a compound that becomes niobium oxide after firing.

  The compound of R means an R oxide and / or a compound that becomes an R oxide after firing.

  (1-2) Next, the barium titanate raw material, the glass component raw material, and the additive component raw material are mixed to obtain a final composition.

  The mixing amount (ratio) of the glass component raw material with respect to 100 moles of the barium titanate raw material is as follows.

The Ba compound to BaO, the Ca compound to CaO, when converted the Si compound to SiO _2,
Preferably,
Ba compound + Ca compound: 0.5 to 12 mol,
Si compound: 0.5 to 12 mol,
More preferably,
Ba compound + Ca compound: 0.5 to 6 mol,
Si compound: 0.5 to 6 mol.

  If the addition amount of the Ba compound, Ca compound and Si compound is too small, densification at a relatively low temperature is difficult, and the temperature characteristics may be adversely affected.

  The mixing amount (ratio) of the additive component raw material with respect to 100 moles of the barium titanate raw material is as follows.

The Mg compound to MgO, the Mn compound to MnO, the Cr compound to _Cr 2 _{O 3,} the V compound to _V 2 _{O 5,} the W compound to WO _3, the Ta compound to _Ta 2 _{O 5,} the Nb compound Nb _When the compound of R is converted to R ₂ O ₃ in ₂ O ₅ ,
Preferably,
Mg compound: 2 mol or less (excluding 0 mol),
Mn compound + Cr compound: 0.5 mol or less (excluding 0 mol),
V compound + W compound + Ta compound + Nb compound: 0.5 mol or less (excluding 0 mol),
R compound: 5 mol or less (excluding 0 mol),
More preferably,
Mg compound: 0.5 to 2 mol,
Mn compound + Cr compound: 0.25 mol or less (excluding 0 mol),
V compound + W compound + Ta compound + Nb compound: 0.01 to 0.1 mol,
R compound: 1 to 3.5 mol.

  If the added amount of the Mg compound is too small, abnormal grain growth tends to occur, and if it is too much, the relative dielectric constant tends to decrease. If the total amount of Mn compound and Cr compound is too large, the relative dielectric constant tends to decrease. When the total amount of V compound, W compound, Ta compound and Nb compound is too large, IR tends to be remarkably lowered. If the amount of R compound added is too large, the sinterability tends to deteriorate.

  Thereafter, the mixed powder is mixed with a dispersion medium such as pure water by a ball mill or the like as necessary, and dried to obtain a dielectric material.

  In addition, as the dielectric material composed of the above components, the above-described 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, for example, They can be appropriately selected from carbonates, oxalates, nitrates, hydroxides, organometallic compounds, and the like, and can also be used as a mixture.

  In addition, what is necessary is just to determine content of each compound in a dielectric raw material so that it may become a composition of the above-mentioned dielectric ceramic composition after baking.

  The average particle diameter of the dielectric material is preferably 0.25 μm or less, more preferably about 0.05 to 0.25 μm before the coating is formed.

  The organic vehicle contains a binder and a solvent. As a binder, various usual binders, such as ethyl cellulose, polyvinyl butyral, an acrylic resin, can be used, for example. The solvent is not particularly limited, and organic solvents such as terpineol, butyl carbitol, acetone, toluene, xylene and ethanol are used.

  The dielectric layer paste can also be formed by kneading a dielectric material and a vehicle in which a water-soluble binder is dissolved in water. The water-soluble binder is not particularly limited, and polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose, water-soluble acrylic resin, emulsion and the like are used.

  The internal electrode layer paste is prepared by kneading the above-mentioned organic vehicle with various oxides, organometallic compounds, resinates, etc. that become the above-mentioned conductive materials or various conductive metals or alloys after baking, and the above-mentioned conductive materials. Is done.

  The external electrode paste is also prepared in the same manner as this internal electrode layer paste.

  The content of the organic vehicle in each paste is not particularly limited, and may be a normal content, for example, about 1 to 5% by weight for the binder and about 10 to 50% by weight for the solvent. Each paste may contain additives selected from various dispersants, plasticizers, dielectrics, insulators, and the like as necessary.

  (2) Next, using the dielectric layer paste containing the dielectric raw material and the internal electrode layer paste, a green chip in which the pre-firing dielectric layer and the pre-firing internal electrode layer are laminated is manufactured. The external electrode paste is printed or transferred onto the capacitor element body 10 formed of a sintered body, which is formed through a binder removal process, a firing process, and an annealing process performed as necessary, and then fired. The electrode 4 is formed and the multilayer ceramic capacitor 1 is manufactured.

  In this embodiment, a dielectric layer composed of a dielectric ceramic composition using a dielectric material containing a barium titanate material in which the half-value width of the diffraction peak of the (111) plane of the perovskite crystal phase is appropriately controlled 2 is formed. As a result, the dielectric particles (grains) 2a after firing can be miniaturized, which can contribute to the thinning of the dielectric layer 2. In addition, even when the dielectric layer 2 is thinned, a multilayer ceramic capacitor 1 having good electrical characteristics (for example, high dielectric constant, CR product, IR lifetime, etc.) and good temperature characteristics satisfying X5R characteristics is obtained. be able to.

  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.

Example 1
Preparation of dielectric material First, a barium titanate material, a glass component material, and an additive component material were prepared.

As a barium titanate raw material, a specific surface area (SSA) is in the vicinity of 10-15 m ² / g, but a value of Δh (111) is different as shown in Table 1, and a plurality of (BaO) _{m ′} · TiO ₂ is different. (However, m ′ = 1.003 or 1.008) was used.
SSA is a value measured by a nitrogen adsorption method, and m ′ is obtained by a glass bead method. The value of Δh (111) is a value calculated as follows.
Half width of diffraction peak of (111) plane by X-ray diffraction (= Δh (111))
With respect to the barium titanate raw material powder, the X-ray generation condition is 50 kV-300 mA and the scan width is 0. 0, between 2θ = 38.5-39.5 ° by a powder X-ray (Cu—Kα ray) diffractometer. Measured under the conditions of 01 °, scan speed of 0.1 ° / min, and X-ray detection conditions of parallel slit of 10 mm, divergent slit of 0.3 mm, and light receiving slit opened, the perovskite crystal phase (111) The half width of the diffraction peak of the surface was measured. In determining the half width separates the data and those ones and K [alpha _2-wire K [alpha ₁ line, utilizing the data for K [alpha ₁ line. The results are shown in Table 1. The measurement was performed at 25 ° C. The X-ray diffraction chart is shown in FIG. 3 (the vertical axis is intensity).

As a glass component raw material, BaCO ₃ , CaCO ₃ and SiO ₂ are wet-mixed at a predetermined ratio by a ball mill for 16 hours, dried, fired in air at 1150 ° C., and further wet-ground by a ball mill for 100 hours. (Ba _0.6 Ca _0.4 ) SiO ₃ (hereinafter also referred to as BCG) was used as the obtained composite oxide.

As additive component materials, MgO, MnO, Y ₂ O ₃ and V ₂ O ₅ having an average particle size of 0.01 to 0.1 μm were used.

Next, BCG as a glass component raw material and MgO, MnO, Y ₂ O ₃ , V ₂ O ₅ as additive component raw materials are added to 100 mol of barium titanate raw material, and water is used as a ball mill. For 16 hours by wet mixing (water pulverization). Thereafter, it was dried with hot air at 130 ° C. to obtain a dielectric material.

The dielectric material is BCG: 3 mol, MgO: 0.5 mol, MnO: 0.2 mol, Y ₂ O ₃ : 2 mol, V ₂ O ₅ : 0.00 mol with respect to 100 mol of barium titanate material. 03 moles were contained.

  Next, a polyvinyl butyral resin and an ethanol-based organic solvent were added to the obtained dielectric material, mixed again by a ball mill, and pasted to obtain a dielectric layer paste.

  Next, 44.6 parts by weight of Ni particles, 52 parts by weight of terpineol, 3 parts by weight of ethyl cellulose, and 0.4 parts by weight of benzotriazole are kneaded with three rolls to obtain a paste for internal electrodes. It was.

Production of Sintered Body A green sheet was formed on a PET film by the doctor blade method using the obtained dielectric layer paste. An internal electrode paste was printed thereon by screen printing. Thereafter, the green sheet to be the lid is peeled from the PET film, a plurality of sheets are laminated so as to have a thickness of about 300 μm, and the desired number of sheets (with the internal electrode paste printed thereon is peeled off from the PET film ( In this case, 5 sheets) were stacked, and a green sheet serving as a lid was again stacked and pressure-bonded to obtain a green chip. At this time, the thickness of the dielectric layer in the green state was 4.5 μm.

Next, the green chip was cut into a predetermined size and subjected to binder removal processing, firing and annealing under the following conditions to obtain a chip sintered body. The binder removal treatment conditions were temperature rising rate: 32.5 ° C./hour, holding temperature: 260 ° C., temperature holding time: 8 hours, and atmosphere: in the air. Firing conditions were as follows: temperature rising rate: 200 ° C./hour, holding temperature: around 1200 ° C. (1180-1240 ° C.), temperature holding time: 2 hours, cooling rate: 200 ° C./hour, atmospheric gas: humidified N ₂ + H ₂ A mixed gas was used. The annealing conditions were temperature rising rate: 200 ° C./hour, holding temperature: 1050 ° C., temperature holding time: 2 hours, cooling rate: 200 ° C./hour, and atmospheric gas: humidified N ₂ gas. A wetter with a water temperature of 20 ° C. was used for humidifying the atmospheric gas during firing and annealing.

  The size of the obtained sintered body was 3.2 mm × 1.6 mm × 0.6 mm, and the number of dielectric layers sandwiched between the internal electrode layers was 4.

Polishing the average particle diameter obtained sintered body of the dielectric grains in the sintered body (dielectric ceramic composition), was subjected to etching, performed the observation of the polished surface with a scanning electron microscope (SEM) The average particle size of the dielectric particles was measured by the code method assuming that the shape of the dielectric particles 2a is a sphere. The average particle size was an average value of 250 measurement points. The evaluation standard is the grain size G.I. S. Is considered to be good when it is 0.25 μm or less. The results are shown in Table 1.

The obtained sintered body was cut at a surface perpendicular to the internal electrode, the cut surface was polished, and a plurality of portions of the polished surface were observed with a metal microscope. Next, the average thickness of the dielectric layer after sintering was determined by performing digital processing on an image observed with a metal microscope. The average thickness of the dielectric layer of each sample was 3.5 μm.

Production of Capacitor Sample and Evaluation of Characteristics After polishing the end face of the obtained chip sintered body by sand blasting, In-Ga was applied as an external electrode to obtain a multilayer ceramic capacitor sample shown in FIG.

  For each of the obtained capacitor samples, the relative dielectric constant ε per 1 μm of dielectric particles, the temperature characteristics of the capacitance (TC), the CR product, and the high temperature load life (IR life) were evaluated.

  With respect to the relative dielectric constant ε (ε / GS) per 1 μm of dielectric particles, first, a digital LCR meter (YHP4284, manufactured by Yokogawa Electric Corporation) was obtained at a reference temperature of 20 ° C. with respect to the obtained capacitor sample. The electrostatic capacity C was measured under the conditions of a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms / μm. Then, the relative dielectric constant ε (no unit) was calculated from the obtained capacitance. Next, the obtained relative dielectric constant ε was divided by the average particle diameter of the dielectric particles measured by the above method to obtain the relative dielectric constant ε per 1 μm of the dielectric particles. The larger the relative dielectric constant per 1 μm of dielectric particles, the better. The evaluation criteria in this example were good when the relative dielectric constant per 1 μm of dielectric particles was 10,000 or more.

  Regarding the temperature characteristics (TC) of the capacitance, the X5R characteristics of the EIAJ standard were evaluated. That is, when the capacitance is measured with a digital LCR meter (4274A manufactured by YHP) under the conditions of a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms, and the reference temperature is 25 ° C. In the temperature range of −55 to 85 ° C., it is checked whether the capacitance change rate with respect to temperature (ΔC / C) satisfies the X5R characteristic (within ± 15%). Was marked with x.

  The CR product was expressed as the product of the capacitance C (μF) measured above and the insulation resistance IR (MΩ). The insulation resistance IR is a value measured after applying DC 4 V / μm to each obtained capacitor sample for 60 seconds at 25 ° C. using an insulation resistance meter (R8340A manufactured by Advantest). The evaluation criteria in this example were good when the CR product was 5000 Ω · F or more.

  Regarding the high temperature load life (IR life), the high temperature load life was measured by holding the capacitor sample in a DC voltage application state of 16 V / μm at 180 ° C. This high temperature load life is particularly important when the dielectric layer is thinned. In this example, the time from the start of application until the resistance drops by an order of magnitude was defined as the lifetime, and this was performed for 10 capacitor samples, and the average lifetime was calculated. The evaluation criteria in this example were good when the IR life was 5 hours or longer.

  These results are shown in Table 1.

  As shown in Table 1, in the case using the barium titanate raw material whose Δh (111) value is too large (samples 1, 3, and 4), the X5R characteristic is satisfied, but a fine sintered body is obtained. (Over 0.25 μm), and it can be confirmed that the electrical characteristics are adversely affected.

  On the other hand, the case (samples 1-1, 2, 4-1, 5, and 6) using the barium titanate raw material in which the value of Δh (111) is controlled to an appropriate value or less satisfies the X5R characteristic. In addition, a fine sintered body is obtained (0.25 μm or less). Along with this, a high value was also obtained for the dielectric constant (ε / GS) per 1 μm of the sintered body obtained by dividing the measured dielectric constant by the particle size of the sintered body. Furthermore, since a fine sintered body was obtained, it can be confirmed that the CR product and the IR life are also excellent.

  That is, the smaller the value of Δh (111), the smaller the barium titanate raw material, the finer the sintered body is obtained when it is used, and in particular, Δh (111) is 0.2 ° or less. In this case, the sintered body particle size was 0.25 μm or less, and a remarkable effect was obtained regarding the miniaturization.

  The reason for the correlation between the value of Δh (111) of the barium titanate raw material and the sintered body particle size is not necessarily clear, but Δh (111) is 0.2 ° or less. In the case, the crystallinity is very good, and there are few micro defects, and as a result, it is considered that the grain growth generated through such micro defects is suppressed.

Example 2
As the barium titanate raw material, Δh (111) is 0.2 ° or less, but the SSA is different as shown in Table 2. A plurality of (BaO) _{m ′} · TiO ₂ (where m ′ = 1.003) ) Was used in the same manner as in Example 1, and thereafter, samples were similarly prepared and evaluated. The results are shown in Table 2.

  As shown in Table 2, when the barium titanate raw material in which Δh (111) of the barium titanate raw material is controlled to 0.2 ° or less and the SSA is in an appropriate range, the X5R characteristics are satisfied, It was confirmed that a much finer sintered body was obtained (0.25 μm or less). Accordingly, a higher value was obtained for the dielectric constant (ε / GS) per 1 μm of the sintered body. Furthermore, since a finer sintered body was obtained, it can be confirmed that the CR product and the IR life are also excellent.

Example 3
As the barium titanate raw material, the specific surface area (SSA) is in the vicinity of 10 to 15 m ² / g and Δh (111) is 0.2 ° or less, but the molar ratio m ′ as the A / B value is shown in Table 3. As shown in FIG. 5, a sample was prepared in the same manner as in Example 1 except that a plurality of (BaO) _{m ′} · TiO ₂ (m ′ = 0.998 to 1.011) were used. And evaluated. The results are shown in Table 3.

  As shown in Table 3, the barium titanate raw material in which Δh (111) of the barium titanate raw material is controlled to 0.2 ° or less, SSA is in the proper range, and the molar ratio m ′ is in the proper range. It was confirmed that when X was used, the X5R characteristic was satisfied and a much finer sintered body was obtained (0.25 μm or less). Accordingly, a higher value was obtained for the dielectric constant (ε / GS) per 1 μm of the sintered body. Furthermore, by obtaining a finer sintered body, it was confirmed that the CR product and the IR life were also excellent.

Example 4
Example 1 (MgO amount 0.5 mol) except that the amount of MgO added to 100 mol of barium titanate raw material was changed to 1 mol, 1.5 mol, 2 mol, 2.5 mol and 3 mol. Similarly, samples were prepared in the same manner, and each sample was evaluated. As a result, it was confirmed that as the amount of Mg increases, the particle size of the sintered body decreases, but the temperature characteristics (particularly the capacity change rate on the high temperature side) tend to deteriorate. Incidentally, it was confirmed that in the case of MgO: 3 mol, the X5R characteristics were not satisfied.

FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of the dielectric layer 2 shown in FIG. FIG. 3 is an X-ray diffraction chart of the barium titanate raw material used in Samples 1 to 6 in Example 1 at a diffraction angle 2θ = 38.5 to 39.5 °.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor 10 ... Capacitor element body 2 ... Dielectric layer 2a ... Dielectric particle (grain)
2b ... Grain boundary phase 3 ... Internal electrode layer 4 ... External electrode

Claims (10)

A method for producing a dielectric ceramic composition having a barium titanate, a glass component, and an additive component,
In X-ray diffraction using Cu—Kα ray as an X-ray source, a diffraction peak of (111) plane is observed, and a barium titanate raw material in which the half width of the diffraction peak is controlled to 0.2 ° or less is used. A method for producing a dielectric ceramic composition, comprising producing the dielectric ceramic composition. ^{2. The} method for producing a dielectric ceramic composition according to claim 1, wherein the barium titanate material has a specific surface area (SSA) measured by a nitrogen adsorption method of 10 to 50 m ² / g. The additive component raw material contains at least an Mg compound,
3. The dielectric ceramic composition according to claim 1, wherein the ratio of the Mg compound to 100 mol of the barium titanate raw material when converted to MgO is Mg compound: 2 mol or less (excluding 0 mol). Manufacturing method. The additive component raw material is further
One or both of a Mn compound and a Cr compound;
One or more selected from V compounds, W compounds, Ta compounds and Nb compounds;
R (wherein R is one or more selected from Sc, Er, Tm, Yb, Lu, Y, Dy, Ho, Tb, Gd and Eu),
Mn compound as MnO, Cr compound as Cr ₂ O ₃ , V compound as V ₂ O ₅ , W compound as WO ₃ , Ta compound as Ta ₂ O ₅ , Nb compound as Nb ₂ O ₅ , R The ratio of the above compound to 100 mol of the barium titanate raw material when converted to R ₂ O ₃ is
Mn compound + Cr compound: 0.5 mol or less (excluding 0 mol),
V compound + W compound + Ta compound + Nb compound: 0.5 mol or less (excluding 0 mol),
The method for producing a dielectric ceramic composition according to claim 3, wherein the compound of R is 5 mol or less (excluding 0 mol). The glass component raw material contains a Ba compound, a Ca compound and a Si compound,
The Ba compound to BaO, the Ca compound to CaO, the ratio with respect to the barium titanate material 100 mole when converted the Si compound to SiO _2,
Ba compound + Ca compound: 0.5 to 12 mol,
Si compound: It is 0.5-12 mol. The manufacturing method of the dielectric ceramic composition in any one of Claims 1-4. The method for producing a dielectric ceramic composition according to claim 5, wherein the glass component raw material is (Ba _1-x Ca _x ) SiO ₃ (where x = 0.3 to 0.7). A dielectric ceramic composition produced by the method according to claim 1. An electronic component having a dielectric layer, wherein the dielectric layer is composed of the dielectric ceramic composition according to claim 7. A multilayer ceramic capacitor having a capacitor element body in which dielectric layers and internal electrode layers are alternately laminated, wherein the dielectric layer is composed of the dielectric ceramic composition according to claim 7. Multilayer ceramic capacitor. The multilayer ceramic capacitor according to claim 9, wherein the internal electrode layer is mainly composed of nickel or a nickel alloy.

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