JP2005162557A - Method of manufacturing dielectric ceramic composition, method of manufacturing dielectric layer-containing electronic component, and dielectric layer-containing electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple method for reducing a short-circuit defect while satisfying a desired temperature characteristic and electric characteristic even in a case that the thickness of a dielectric layer is a super thin layer of, for example, ≤4.5 μm. <P>SOLUTION: In the method of manufacturing a dielectric ceramic composition, at least a part of assistant components is mixed to prepare powder before calcining. Next, the powder before calcining is calcined to prepare calcined powder and the dielectric ceramic composition is obtained by mixing an essential component having barium titanate and a titanium compound with the calcined powder. Titanium oxide is added so that the essential component molar ratio (Ba/Ti) of barium to titanium in the essential components is ≥1 and the final molar ratio (Ba/Ti) of barium to titanium in the final dielectric ceramic composition is 1.004-1.021 and after that, main firing is carried out. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a dielectric ceramic composition, a method for producing a dielectric layer-containing electronic component, and a dielectric layer-containing electronic component such as a multilayer ceramic capacitor obtained by the method.

  Multilayer ceramic capacitors are widely used as small-sized, large-capacity, and high-reliability electronic components, and the number used in electrical and electronic devices is large. In recent years, with the miniaturization and high performance of devices, the demand for further miniaturization, larger capacity, lower cost, and higher reliability of multilayer ceramic capacitors has become increasingly severe.

  A multilayer ceramic capacitor is usually manufactured by laminating an internal electrode paste and a dielectric slurry (paste) by a sheet method, a printing method, or the like, followed by firing. In general, Pd and Pd alloys have been used for the internal electrodes. However, since Pd is expensive, relatively inexpensive Ni and Ni alloys are being used. By the way, when the internal electrode is formed of Ni or Ni alloy, there is a problem that the electrode is oxidized if firing is performed in the atmosphere. For this reason, generally, after debinding, firing is performed at an oxygen partial pressure lower than the equilibrium oxygen partial pressure of Ni and NiO, and then the dielectric layer is reoxidized by heat treatment.

  However, when firing in a reducing atmosphere, the dielectric layer is reduced and the specific resistance is reduced. Therefore, a reduction-resistant dielectric material that has not been reduced even when fired in a reducing atmosphere has been proposed.

  However, multilayer ceramic capacitors using these reduction-resistant dielectric materials have a problem that the high-temperature accelerated life of insulation resistance (IR) is short and the reliability is low. In addition, there is a problem that the dielectric constant of the dielectric decreases with time, which is particularly remarkable under a direct current electric field. If the thickness of the dielectric layer is reduced in order to reduce the size and capacity of the multilayer ceramic capacitor, the electric field strength applied to the dielectric layer when a DC voltage is applied increases. For this reason, the change with time of the relative permittivity becomes remarkably large.

  By the way, in the multilayer ceramic capacitor, it is necessary that the rate of change of capacitance is small in a wide temperature range. In the standard called X7R characteristic defined in the EIA standard, the rate of change of capacitance is defined within ± 15% (reference temperature 25 ° C.) between −55 ° C. and 125 ° C. Further, in a standard called B characteristic (JIS standard), it is set within ± 10% (reference temperature 20 ° C.) between −25 to 85 ° C.

  As a dielectric material satisfying these temperature characteristics or a manufacturing method thereof, for example, the compositions and manufacturing methods described in Patent Documents 1 to 3 below are known.

  In the invention described in Patent Document 1, in order to satisfy the temperature characteristics, after calcining the dielectric main component and subcomponent, a glass component containing Ba or the like is added to the calcined powder, followed by firing. Is disclosed.

  Further, in Patent Document 2, in order to satisfy the temperature characteristics, at least one selected from magnesium oxide, yttrium oxide, barium oxide and calcium oxide as a subcomponent in a dielectric main component made of barium titanate, and A composition comprising at least one selected from silicon oxide, manganese oxide, vanadium oxide and molybdenum oxide is disclosed.

Furthermore, Patent Document 3 describes that BaCO ₂ and TiO ₂ may be added to the raw material powder in order to adjust the Ba / Ti ratio of barium titanate.

However, in these documents, in any case, when the dielectric layer thickness is an ultra-thin layer of 4.5 μm or less, for example, the short-circuit defect rate is reduced while satisfying desired temperature characteristics and electrical characteristics. No mention is made of the method. If the dielectric layer is thinned in order to improve the capacitance, the short-circuit defect rate increases.
JP-A-6-5460 JP-A-8-124785 JP-A-8-191031

  The present invention has been made in view of such a situation, and an object thereof is to realize a short circuit while satisfying desired temperature characteristics and electrical characteristics even in the case of an ultrathin layer having a dielectric layer thickness of, for example, 4.5 μm or less. An object is to provide a simple method for reducing the defect rate.

In order to achieve the above object, a method for producing a dielectric ceramic composition according to the present invention comprises:
Mixing at least a part of the subcomponents and preparing a powder before calcining;
A step of calcining the pre-calcined powder to prepare a calcined powder;
A step of mixing the calcined powder with at least a main component having barium titanate and a titanium compound, followed by firing to obtain a dielectric ceramic composition, comprising: ,
The main component molar ratio (Ba / Ti) of barium and titanium in the main component barium titanate is 1 or more, and the final molar ratio (Ba / Ti) of barium and titanium in the final dielectric ceramic composition is The titanium compound is added so as to be 1.004 to 1.021, followed by main firing.

Preferably, the titanium compound is a titanium oxide, and titanium oxide is added to the calcined powder, followed by a main firing.

  In the present invention, a titanium compound such as titanium oxide is added to a calcined powder afterwards, and the dielectric layer has a desired thickness even in the case of an ultra-thin layer of 4.5 μm or less, for example. The short-circuit defect rate can be reduced while satisfying temperature characteristics and electrical characteristics. Such new knowledge was first discovered by the present inventors.

  Preferably, the final molar ratio (Ba / Ti) is 1.006 to 1.019, more preferably 1.010 to 1.016. By adding a titanium compound such as titanium oxide so as to be in such a range, the short-circuit defect rate can be particularly reduced.

Preferably, as the other accessory component,
Selected from magnesium compounds, yttrium compounds, scandium compounds, europium compounds, gadolinium compounds, dysprosium compounds, holmium compounds, erbium compounds, thulium compounds, ytterbium compounds, lutetium compounds, terbium compounds, barium compounds, strontium compounds and calcium compounds At least one,
At least one selected from a silicon compound, a manganese compound, a chromium compound, a vanadium compound, a molybdenum compound, a tungsten compound, a niobium compound, and a tantalum compound is mixed with the pre-calcined powder and calcined.

Preferably, the main component barium titanate is BaTiO ₃ , the magnesium compound is MgO, the yttrium compound is Y ₂ O ₃ , the scandium compound is Sc ₂ O ₃ , the europium compound is Eu ₂ O ₃ , and gadolinium. The compound is Gd ₂ O ₃ , the dysprosium compound is Dy ₂ O ₃ , the holmium compound is Ho ₂ O ₃ , the erbium compound is Er ₂ O ₃ , the thulium compound is Tm ₂ O ₃ , and the ytterbium compound is Yb ₂ O ₃ , lutetium compound Lu ₂ O ₃ , terbium compound Tb ₂ O ₃ , barium compound BaO, strontium compound SrO, calcium compound CaO, silicon compound SiO ₂ , manganese compound MnO, chromium compound in Cr ₂ O ₃ , vanadium compound Is converted to V ₂ O ₅ , the molybdenum compound is converted to MoO ₃ , the tungsten compound is converted to WO ₃ , the niobium compound is converted to Nb ₂ O ₅ , and the tantalum compound is converted to Ta ₂ O ₅ , respectively.
BaTiO ₃ : The ratio to 100 mol is
MgO: 0.1-3 mol,
Y ₂ O ₃ , Sc ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O ₃ , Or Tb ₂ O ₃ : more than 0 mol and 5 mol or less,
BaO + CaO + SrO: 0.2-12 mol,
SiO _2: 0.2~12 mol,
MnO or Cr ₂ O ₃ : more than 0 mol and 1.0 mol or less,
_{V 2 O 5, MoO 3,} WO 3, Nb 2 O 5 or _Ta 2 _O 5,: _0~0.3 mol,
_{V 2 O 5 + MoO 3 +} WO 3 + Nb 2 O 5 + Ta 2 O 5: 0 so that the molar excess, calcined to prepare the pre-calcination powder.

  By including these subcomponents in a predetermined ratio and calcining, the temperature characteristics of the capacitance such as X7R or B characteristics can be easily satisfied, and the relative permittivity, dielectric loss, insulation Electrical characteristics such as resistance can be improved.

Preferably, substantially no titanium oxide is added to the pre-calcination powder. Preferably, with respect to BaTiO ₃ : 100 mol, the titanium compound is converted into TiO ₂ in the calcined powder, preferably 0.1 to 1.8 mol, more preferably 0.4 to 1 .4 moles are added, followed by firing. By adding the titanium compound in such a range, the effect of the present invention is improved.

  In the method for producing a dielectric layer-containing electronic component according to the present invention, the dielectric layer is formed using the dielectric ceramic composition obtained by any one of the above methods.

  Preferably, the thickness of the dielectric layer is 4.5 μm or less, more preferably 3 μm or less, and particularly preferably 1.0 μm or less.

  The dielectric layer-containing electronic component according to the present invention is manufactured by the method described above. In this case, the dielectric layer is sandwiched between electrode layers containing nickel or a nickel alloy.

Preferably, nickel is contained in the grain boundary of the dielectric layer in a proportion of 0.9% by weight or less, more preferably 0.7% by weight or less in terms of NiO. The grain boundary of the dielectric layer contains manganese and / or chromium in a ratio of 0.35% by weight or less, more preferably 0.23% by weight or less in terms of MnO or Cr ₂ O ₃ .

Preferably, the grain boundary of the dielectric layer is 3.5 wt% or less, more preferably 3.2 wt% in terms of rare earth oxide (R ₂ O ₃ ), such as yttrium or scandium. % Or less. Furthermore, preferably, the grain boundary of the dielectric layer contains titanium in a proportion of 32% by weight or more, more preferably 34% by weight or more in terms of TiO ₂ . Preferably, the grain boundary of the dielectric layer contains silicon in a proportion of 4.7% by weight or less, more preferably 4.0% by weight or less in terms of SiO ₂ . Furthermore, the ratio A / B (Ba / Ti) of barium and titanium at the grain boundary of the dielectric layer is preferably 0.95 or less, more preferably 0.80 or less.

In the grain boundary in the dielectric layer obtained by the production method of the present invention, the diffusion of nickel from the internal electrode is reduced, the grain boundary concentration of MnO, R ₂ O ₃ and SiO ₂ components is reduced, and the TiO ₂ component is reduced. Grain boundary concentration increases. For this reason, it is considered that the short-circuit defect rate is reduced and the decrease in VB is suppressed.

  In the present invention, the rare earth (R) is at least one selected from Sc, Er, Tm, Yb, Lu, Y, Dy, Ho, Tb, Gd, and Eu, for example.

  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.
2A and 2B are graphs showing the effect of post-added titanium oxide in one embodiment of the present invention,
FIG. 3 is a photograph showing a cross section of the main part of a multilayer ceramic capacitor obtained by the manufacturing method according to the embodiment of the present invention.
FIG. 4 is a photograph of a cross section of the main part of a multilayer ceramic capacitor obtained by the manufacturing method according to the embodiment of the present invention, taken with a scanning transmission electron microscope.
5A and 5B are graphs showing the effects of post-added titanium oxide in another example of the present invention.

Multilayer ceramic capacitor Before describing the method for producing a dielectric ceramic composition according to the present invention, a multilayer ceramic capacitor will be described first.

  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. Also, there is no particular limitation on the size, and it may be an appropriate size according to the application, but is usually (0.6 to 5.6 mm, preferably 0.6 to 3.2 mm) × (0.3 ˜5.0 mm, preferably 0.3 to 1.6 mm) × (0.3 to 1.9 mm, preferably 0.3 to 1.6 mm).

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

Dielectric layer 2
The dielectric layer 2 is composed of 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 is:
A main component having barium titanate;
As a minor component
Selected from magnesium compounds, yttrium compounds, scandium compounds, europium compounds, gadolinium compounds, dysprosium compounds, holmium compounds, erbium compounds, thulium compounds, ytterbium compounds, lutetium compounds, terbium compounds, barium compounds, strontium compounds and calcium compounds At least one,
And at least one selected from a silicon compound, a manganese compound, a chromium compound, a vanadium compound, a molybdenum compound, a tungsten compound, a niobium compound, and a tantalum compound.

The main component barium titanate is changed to BaTiO ₃ .
Magnesium compound in MgO, yttrium compound in Y ₂ O ₃ , scandium compound in Sc ₂ O ₃ , europium compound in Eu ₂ O ₃ , gadolinium compound in Gd ₂ O ₃ and dysprosium compound in Dy ₂ O ₃ , holmium compound in Ho ₂ O ₃ , erbium compound in Er ₂ O ₃ , thulium compound in Tm ₂ O ₃ , ytterbium compound in Yb ₂ O ₃ , lutetium compound in Lu ₂ O ₃ , terbium compound Tb ₂ O ₃ , barium compound BaO, strontium compound SrO, calcium compound CaO, silicon compound SiO ₂ , manganese compound MnO, chromium compound Cr ₂ O ₃ , vanadium compound V ₂ O ₅ , molybdenum compound MoO ₃ , tungsten compound When the product is converted to WO ₃ , the niobium compound is converted to Nb ₂ O ₅ and the tantalum compound is converted to Ta ₂ O ₅ ,
The ratio of BaTiO ₃ : 100 mol in the dielectric ceramic composition is
MgO: 0.1-3 mol, preferably 0.5-2.0 mol,
Y ₂ O ₃ , Sc ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O ₃ , Or Tb ₂ O ₃ : more than 0 mol and 5 mol or less, preferably 0.1 to 5 mol, more preferably 0.5 to 4.5 mol, still more preferably 1.0 to 3.5 mol,
BaO + CaO + SrO: 0.2-12 mol, preferably 2-6 mol,
SiO ₂ : 0.2 to 12 mol, preferably 2 to 6 mol,
MnO or Cr ₂ O ₃ : more than 0 mol and 1.0 mol or less, preferably 0.01 to 0.4 mol,
_{V 2 O 5, MoO 3,} WO 3, Nb 2 O 5 or _Ta 2 _O 5,: _0~0.3 mol, preferably 0 to 0.25 mol,
_{V 2 O 5 + MoO 3 +} WO 3 + Nb 2 O 5 + Ta 2 O 5: 0 mol greater, preferably 0.01 to 0.3 mol, more preferably 0.05 to 0.25 mol.

  In this specification, each oxide constituting the main component and each subcomponent is represented by a stoichiometric composition, but the oxidation state of each oxide may be out of the stoichiometric composition. However, the said ratio of each subcomponent is calculated | required by converting into the oxide of the said stoichiometric composition from the metal amount contained in the oxide which comprises each subcomponent. In addition, as the raw material powder of the dielectric ceramic composition, 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.

  The dielectric ceramic composition may contain other compounds, but it is preferable that cobalt oxide does not substantially contain cobalt oxide because it increases the capacity change rate.

  The reasons for limiting the contents of the subcomponents are as follows.

When the content of magnesium oxide is too small, it tends to be difficult to reduce the change with time of the capacity. Moreover, when there is too much content of magnesium oxide, sinterability will deteriorate rapidly, densification will become inadequate and IR accelerated lifetime will fall, and it exists in the tendency for a high dielectric constant to be not acquired.

  Yttrium oxide (the same applies to other rare earth oxides / the same applies hereinafter) has the effect of improving the IR accelerated lifetime and also improves the DC bias characteristics. If the content of rare earth oxides such as yttrium oxide is small, the effect of addition becomes insufficient, and in particular, the DC bias characteristics tend to be insufficient. When the content of the rare earth oxide is too large, the relative dielectric constant is lowered, and the sinterability is lowered and the densification tends to be insufficient.

If the content of BaO + CaO + SrO is too small, the change with time of the capacity when a DC electric field is applied becomes large, the IR accelerated life becomes insufficient, and the temperature characteristic of the capacity tends not to be in a desired range. is there. When the content is too large, the IR accelerated lifetime becomes insufficient, and the relative permittivity tends to decrease rapidly. If the content of SiO ₂ is too small, densification sintering property is lowered becomes insufficient, while when too large, there is a tendency that the initial insulation resistance is too low.

  Manganese oxide or chromium oxide has an action of densifying the dielectric layer and an action of improving the IR accelerated lifetime. However, if the content is too large, it is difficult to reduce the time-dependent change in capacity when a DC electric field is applied. Tend to be.

Vanadium oxide, molybdenum oxide, tungsten oxide, niobium oxide, and tantalum oxide improve the change in capacity over time under a direct current electric field. Further, these oxides improve the dielectric breakdown voltage (VB) and the IR life. However, if the content of V ₂ O ₅ , MoO ₃ , WO ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ is too large, the initial IR tends to be extremely lowered.

In addition to the above oxides, Al ₂ O ₃ may be included in the dielectric layer. Al ₂ O ₃ does not significantly affect the capacity-temperature characteristics, and shows the effect of improving the sinterability, the insulation resistance, and the accelerated life (IR life) of the insulation resistance. However, if the content of Al ₂ O ₃ is too large, the sinterability deteriorates and the IR becomes low. Therefore, Al ₂ O ₃ is preferably 1 mol or less with respect to 100 mol of the main component.

  The average crystal grain size of the dielectric ceramic composition of the present invention is not particularly limited, and is determined according to the thickness of the dielectric layer. For example, when the thickness of the dielectric layer is 3 μm, the crystal grain size is preferably Is 1.0 μm or less, more preferably 0.1 to 0.6 μm. When the thickness of the dielectric layer is 0.9 μm, the crystal grain size is preferably 0.5 μm or less, more preferably 0.1 to 0.1 μm. 0.3 μm.

The dielectric layer 2 of the present invention is composed of crystal grains and grain boundaries. The grain boundary contains nickel in a proportion of 0.9% by weight or less, more preferably 0.7% by weight or less in terms of NiO, and manganese and / or chromium in terms of MnO or Cr ₂ O _3. , Preferably 0.35% by weight or less, more preferably 0.23% by weight or less, and rare earths converted to rare earth oxides (R ₂ O ₃ ), and more preferably 3.5% by weight or less. It is contained in a proportion of 3.2% by weight or less, and titanium is contained in a proportion of 32% by weight or more, more preferably 34% by weight or more. Furthermore, silicon is contained in the grain boundary of the dielectric layer 2 in a proportion of preferably 4.7% by weight or less, more preferably 4.0% by weight or less, in terms of SiO ₂ . The ratio A / B (Ba / Ti) between barium and titanium at the grain boundary of the dielectric layer 2 is preferably 0.95 or less, more preferably 0.80 or less.

In the grain boundary in the dielectric layer obtained by the production method of the present invention, the diffusion of nickel from the internal electrode is reduced, the grain boundary concentration of MnO, R ₂ O ₃ and SiO ₂ components is reduced, and the TiO ₂ component is reduced. Grain boundary concentration increases. For this reason, it is considered that the short-circuit defect rate is reduced and the decrease in VB is suppressed.

  Various conditions such as the thickness and the number of layers of the dielectric layer composed of the dielectric ceramic composition of the present invention may be appropriately determined according to the purpose and application. For example, the thickness of the dielectric layer is usually 50 μm or less per layer, and in the present invention, it is particularly effective even in the case of an ultrathin layer of 4.5 μm or less, 3 μm or less, 2 μm or less, or 1 μm or less.

  The dielectric ceramic composition of the present invention is particularly effective for reducing the short-circuit defect rate of a multilayer ceramic capacitor having such a thinned dielectric layer. The number of laminated dielectric layers is usually about 2 to 1000, preferably about 10 to 1000.

  The multilayer ceramic capacitor using the dielectric ceramic composition of the present invention is particularly suitable for use as an electronic device for equipment used in an environment of −25 to 85 ° C. In such a temperature range, the temperature characteristic of the capacitance can satisfy the B characteristic of JIS standard [capacitance change rate within ± 10% at −25 to 85 ° C. (reference temperature 20 ° C.)].

  In a multilayer ceramic capacitor, an AC electric field of 0.02 V / μm or more, particularly 0.2 V / μm or more, more preferably 0.5 V / μm or more, and generally about 5 V / μm or less is superimposed on the dielectric layer. Then, a DC electric field of 5 V / μm or less is applied, but in the dielectric ceramic composition of the present invention, the capacitance temperature characteristics are extremely stable even when such an electric field is applied.

Internal electrode layer 3
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.

  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 may be appropriately determined according to the use, etc., but is usually 0.5 to 5 μm, preferably 0.5 to 2.5 μm, and more preferably about 1 to 2 μm.

External electrode 4
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 may be appropriately determined according to the application, but is usually preferably about 10 to 100 μm.

Manufacturing method of multilayer ceramic capacitor The multilayer ceramic capacitor manufactured by using the method of manufacturing a dielectric ceramic composition according to the present invention has a green chip formed by a normal printing method or a sheet method using a paste. It is manufactured by producing and firing, and then printing or transferring the external 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 the powder of BaTiO _{3 in} the dielectric ceramic composition powder, not only a powder obtained by a so-called solid phase method in which raw materials are usually mixed, calcined and pulverized, but also an oxalate method, a hydrothermal synthesis method, etc. It may be a powder obtained by a so-called liquid phase method.

In this embodiment, before the dielectric ceramic composition powder having the above-described composition is obtained, the subcomponents are calcined except for titanium (including the compound). When calcining, for example, as a subcomponent,
Selected from magnesium compounds, yttrium compounds, scandium compounds, europium compounds, gadolinium compounds, dysprosium compounds, holmium compounds, erbium compounds, thulium compounds, ytterbium compounds, lutetium compounds, terbium compounds, barium compounds, strontium compounds and calcium compounds At least one,
In the case of having at least one selected from a silicon compound, a manganese compound, a chromium compound, a vanadium compound, a molybdenum compound, a tungsten compound, a niobium compound, and a tantalum compound, at least a part of the subcomponents except for titanium oxide Pre-baked.

  Thereafter, at least titanium oxide and barium titanate as the main component are mixed with the calcined subcomponent, and the final molar ratio (Ba / Ti) of barium to titanium in the final composition is 1.004. Adjust to ˜1.021. For example, at the time of calcining, only the subcomponents excluding titanium oxide are calcined, and barium titanate as a main component and titanium oxide are added to the calcined powder.

In the present embodiment, the amount (post-addition) of titanium oxide added to the calcined powder is preferably 0.3 to 1. in terms of TiO ₂ with respect to BaTiO ₃ : 100 mol. It is 6 mol, More preferably, it is 0.6-1.2 mol. The effect of this invention increases by adding after in such a range.

Note that the subcomponent is not necessarily in the form of an oxide, and a compound that becomes an oxide by heat treatment can be used as a subcomponent material. For example, as a compound which becomes MgO or CaO by heat treatment, MgCO ₃ , MgCl ₂ , MgSO ₄ , Mg (NO ₃ ) ₂ , Mg (OH) ₂ , (MgCO ₃ ) ₄ Mg (OH) ₂ , CaCO ₃ , CaCl ₂ , CaSO ₄ , Ca (NO ₃ ) ₂ , Mg alkoxide, Ca alkoxide, etc., or their hydrates. Examples of the compound that becomes MnO by heat treatment include MnCO ₃ , MnCl ₂ , MnSO ₄ , Mn (NO ₃ ) ₂ , and their hydrates. Examples of the compound that becomes Y ₂ O ₃ by heat treatment include YCl ₃ , Y ₂ (SO ₄ ) ₃ , Y (NO ₃ ) ₃ , Y (CH ₃ COO) ₃ , Y alkoxide, and the like, or a hydrated substance thereof. Illustrated. Further, examples of the compound that becomes V ₂ O ₅ by the heat treatment include VCl ₅ , V ₂ (SO ₄ ) ₅ , V (NO ₃ ) _{5, and the} like, or hydrates thereof.

  Although the calcining conditions of the powder before calcining are not particularly limited, it is preferably performed under the following conditions.

Temperature increase rate: 50 to 400 ° C./hour, particularly 100 to 300 ° C./hour,
Holding temperature: 500 ° C to 1300 ° C, preferably 500 ° C to less than 1200 ° C,
Temperature holding time: 0.5 to 6 hours, especially 1 to 3 hours,
Atmosphere: in air and nitrogen.

  The calcined powder that has been calcined is coarsely pulverized with an alumina roll or the like, and then at least titanium oxide is added. If necessary, the remaining additives (main component and / or subcomponent) are added. Thus, a mixed powder having the final composition described above is obtained. Thereafter, the mixed powder is mixed by a ball mill or the like, if necessary, and dried to obtain a dielectric ceramic composition powder having the composition of the present invention.

  Next, the finally 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.

  The particle size of the dielectric ceramic composition powder is usually about 0.05 to 0.5 [mu] m, preferably about 0.1 to 0.4 [mu] m before the coating.

  An organic vehicle is obtained by dissolving a binder (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. Moreover, the organic solvent to be used is not particularly limited, and may be appropriately selected from various organic solvents such as terpineol, butyl carbitol, methyl ethyl ketone, acetone, and toluene depending on the method to be used such as a printing method and 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 includes the above-mentioned conductive materials made of various dielectric metals and alloys, or various oxides, organometallic compounds, resinates, etc. (conductive materials, etc.) that become the above-mentioned conductive materials after firing, and the above-described organic vehicles. And kneading. The shape of the conductive material or the like in the paste is not particularly limited, and examples thereof include a spherical shape and a scale shape, and a mixture of these shapes may be used.

  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 auxiliary additives selected from various dispersants, plasticizers, dielectrics, insulators, and the like as necessary. The total content of these auxiliary additives is preferably 10% by weight or less.

  In addition, as a plasticizer, polyethyleneglycol, a phthalate ester (for example, dioctyl phthalate, dibutyl phthalate) etc. are used, for example. Examples of the dispersant include oleic acid, rosin, glycerin, octadecylamine, ethyl oleate, and menseden oil.

  In particular, when preparing the dielectric layer paste (slurry), the content of the dielectric ceramic composition powder in the paste is about 50 to 80% by weight with respect to the entire paste, and the binder is 2 to 2%. 5 wt%, plasticizer is preferably 0.1 to 5 wt%, dispersant is 0.1 to 5 wt%, and solvent is preferably about 20 to 50 wt%.

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

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

  Before firing, the green chip is subjected to binder removal processing. The binder removal treatment may be performed under normal conditions, but when a base metal such as Ni or Ni alloy is used as the conductive material of the internal electrode layer, it is particularly preferable to perform under the following conditions.

Temperature increase rate: 5 to 300 ° C./hour, particularly 10 to 100 ° C./hour,
Holding temperature: 180-400 ° C, especially 200-300 ° C,
Temperature holding time: 0.5 to 24 hours, especially 5 to 20 hours,
Atmosphere: in the air.

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 ⁻⁸ to 10 ⁻¹² atm. When the oxygen partial pressure is less than the above range, the conductive material of the internal electrode layer tends to be abnormally sintered and interrupted. Further, when the oxygen partial pressure exceeds the above range, the internal electrode layer tends to be oxidized.

  The holding temperature during firing is preferably 1100 to 1350 ° C, particularly 1150 to 1300 ° C. When the holding temperature is lower than the above range, densification is insufficient, and when the holding temperature is higher than the above range, the change with time of the capacity when a DC electric field is applied tends to increase.

  Various conditions other than the above conditions are preferably as follows.

Temperature increase rate: 50 to 500 ° C./hour, particularly 200 to 300 ° C./hour temperature,
Retention time: 0.5-8 hours, especially 1-3 hours,
Cooling rate: 50 to 500 ° C./hour, particularly 200 to 300 ° C./hour,
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 after being humidified.

  When firing in a reducing atmosphere, the chip body is preferably annealed. Annealing is a process for re-oxidizing the dielectric layer, which can significantly increase the IR accelerated lifetime.

The oxygen partial pressure in the annealing atmosphere is preferably 10 ⁻⁶ atm or more, particularly 10 ⁻⁵ to 10 ⁻⁴ atm. 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. If the holding temperature is less than the above range, the dielectric layer tends to be insufficiently oxidized and the lifetime tends to be shortened. If the holding temperature exceeds the above range, the internal electrode layer is oxidized and the capacity is reduced. It tends to react with the substrate and shorten its life. Note that the annealing step may be composed of only temperature rise and temperature drop. In this case, the temperature holding time is zero, and the holding temperature is synonymous with the maximum temperature.

  Various conditions other than the above conditions are preferably as follows.

Temperature holding time: 0 to 20 hours, especially 6 to 10 hours,
Cooling rate: 50 to 500 ° C./hour, in particular 100 to 300 ° C./hour,
It is preferable to use humidified N2 gas or the like as the atmosphere gas.

Incidentally, the above-mentioned binder removal treatment, each step of firing and annealing, to wet the N ₂ gas or mixed gas etc. may be used, for example a wetter etc.. 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. When these are performed continuously, after removing the binder, the atmosphere is changed without cooling, and then the temperature is raised to the holding temperature at the time of baking to perform baking, and then cooled to reach the annealing holding temperature. Sometimes it is preferable to perform annealing by changing the atmosphere. On the other hand, when performing these independently, at the time of firing, after raising the temperature under N ₂ gas atmosphere with N ₂ gas or wet to the holding temperature of the binder removal processing, further continuing the heating to change the atmosphere Preferably, after cooling to the holding temperature at the time of annealing, it is preferable to change to the N ₂ gas or humidified N ₂ gas atmosphere again and continue cooling. In annealing, the temperature may be changed to a holding temperature in an N ₂ gas atmosphere, and then the atmosphere may be changed, or the entire annealing process may be a humidified N ₂ gas atmosphere.

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 this embodiment manufactured as described above has a capacitance-temperature change rate satisfying the B characteristic of EIAJ standard even when the dielectric layer is an ultrathin layer having a thickness of 4.5 μm or less. Excellent electrical characteristics such as dielectric constant, dielectric loss, insulation resistance, capacitance change rate under DC bias, and short-circuit failure rate are also low.

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.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention.

For example, the dielectric ceramic composition obtained by the manufacturing method according to the present invention is not used only for a multilayer ceramic capacitor, but may be used for other electronic components on which a dielectric layer is formed.

Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

Example 1
A sample of the multilayer ceramic capacitor was prepared by the following procedure.

First, the following pastes were prepared.

Dielectric layer paste First, a main component material and a subcomponent material were prepared. As the main component material, BaTiO ₃ having an average particle diameter of 0.2 μm obtained by a hydrothermal synthesis method was used. As subcomponents, as shown in Table 1, compounds that become MgO, MnO, Y ₂ O ₃ , V ₂ O ₅ , BaO, CaO, and SiO ₂ after heat treatment are converted into these oxides. It was used so that the relationship of mol% shown in FIG. Carbonates were used as raw materials for MgO and MnO, and oxides were used as other subcomponent raw materials. As the magnesium carbonate as a raw material for MgO, (MgCO ₃ ) ₄ Mg (OH) ₂ .5H ₂ O was used. Moreover, MnCO ₃ was used as a carbonate as a raw material of MnO.

First, after heat treatment, the compounds that become MgO, MnO, Y ₂ O ₃ , V ₂ O ₅ , BaO, CaO, and SiO ₂ were calcined so as to have the mol% in Table 1. The conditions for calcining were as follows.

Temperature increase rate: 300 ° C / hour,
Holding temperature: 500 to 1350 ° C.
Temperature holding time: 3 hours
Atmosphere: in the air.

The material obtained by this calcining is pulverized for 1 hour with a raikai machine to obtain a calcined powder. Thereafter, barium titanate (BaTiO ₃ ) as a main component is added to the calcined powder as 100. The final composition of Sample Nos. 1 to 5 was added after the addition of mol% and titanium oxide (TiO ₂ ) at a ratio of 0 to 1.9 mol% (post-addition), wet-mixed for 16 hours with a zirconia ball mill. A dielectric ceramic composition powder was obtained. In addition, in the dielectric ceramic composition powder having the final composition of Sample No. 6, 0.9 mol% of titanium oxide was added to the pre-calcination powder, and calcined simultaneously with other subcomponents, and calcined. No titanium oxide was added to the powder.

  Further, in the dielectric ceramic composition powder having the final composition of Sample Nos. 7 and 8, the molar ratio (Ba / Ti) of the main component barium titanate is 1.000 for Sample No. 7 and 0.000 for Sample No. 8. The calcined subcomponent (not including titanium oxide) was added to the main component of 995, and no titanium oxide was added thereafter.

Furthermore, in the dielectric ceramic composition powder having the final composition of Sample No. 9, subcomponents (including TiO ₂ ) were added to the main component barium titanate without performing calcination.

  Further, in the dielectric ceramic composition powder having the final composition of sample number 10, the minor component (Ba / Ti) of the main component has a molar ratio (Ba / Ti) of 0.995, and the auxiliary component pre-calcined powder ( Titanium oxide was not included), and titanium oxide was added.

  As shown in Table 1, the main component molar ratio (Ba / Ti) of barium and titanium in the main component is 1.004 for sample numbers 1 to 6, 9, and 1.000 for sample number 7. The sample numbers 8 and 10 were 0.995. This is because in Sample Nos. 7, 8, and 10, the molar ratio of the main component (Ba / Ti) was changed.

  As shown in Table 1, the final molar ratio (Ba / Ti) between barium and titanium in the final dielectric ceramic composition was 1.022 in Sample No. 1. This is because in Sample No. 1, titanium oxide was not added to barium titanate, which is the main component.

Moreover, as shown in Table 1, in the sample numbers 2 to 10, the final molar ratio (Ba / Ti) was as small as 1.021 or less. In Sample Nos. 2 to 5, since the titanium oxide was added to the main component barium titanate together with the calcined powder, the final molar ratio (Ba / Ti) was reduced to 1.021 or less. In Sample No. 6, since the additive as additive and titanium oxide were pre-calcined and added to the main component, barium titanate, the final molar ratio (Ba / Ti) was reduced to 1.021 or less. It was. In Sample Nos. 7 and 8, titanium oxide was not added, but the final molar ratio (Ba / Ti) was also small because the original main component molar ratio (Ba / Ti) was small. In sample number 9, the final molar ratio (Ba / Ti) was reduced to 1.021 or less because titanium oxide and other subcomponents were added to the main component barium titanate without calcining.

このようにして得られた最終組成の誘電体磁器組成物粉体１００重量部と、アクリル樹脂４．８重量部と、トルエン１０重量部と、酢酸エチル７０重量部と、ミネラルスピリット６重量部と、アセトン４重量部とをボールミルで混合し、ペースト化した。 In Sample No. 10, titanium oxide was added to the main component barium titanate together with the calcined powder, but the final molar ratio (Ba / Ti) was 1 because the main component molar ratio (Ba / Ti) was small. 0.02 or less.

100 parts by weight of the dielectric ceramic composition powder of the final composition thus obtained, 4.8 parts by weight of acrylic resin, 10 parts by weight of toluene, 70 parts by weight of ethyl acetate, 6 parts by weight of mineral spirits, Then, 4 parts by weight of acetone was mixed with a ball mill to form a paste.

Internal electrode layer paste 100 parts by weight of Ni particles having an average particle diameter of 0.4 μm, 40 parts by weight of an organic vehicle (8 parts by weight of ethyl cellulose resin dissolved in 92 parts by weight of butyl carbitol) and butyl carbitol 10 parts by weight was kneaded with three rolls to form a paste.

External electrode paste 100 parts by weight of Cu particles having an average particle size of 0.5 μm, 35 parts by weight of an organic vehicle (8 parts by weight of ethyl cellulose resin dissolved in 92 parts by weight of butyl carbitol) and 7 parts of butyl carbitol The parts by weight were kneaded to form a paste.

Production of green chip A green sheet having a thickness of 1.5 m was formed on a PET film using the dielectric layer paste. After printing the internal electrode paste on the surface of the green sheet, the sheet was peeled off from the PET film. Next, 5 layers of green sheets after printing the internal electrode layer paste are stacked with a plurality of protective green sheets (not printed with internal electrode layer paste), and then pressed under conditions of 120 ° C. and 15 Pa. To get a green chip.

Firing First, the green chip is cut into a predetermined size, binder removal, firing and annealing are performed under the following conditions, an external electrode is formed, and the multilayer ceramic capacitor having the configuration shown in FIG. 1 is formed. Samples (Sample Nos. 1 to 10) were obtained.

Debinder processing conditions Temperature rising rate: 15 ° C / hour,
Holding temperature: 280 ° C.
Temperature holding time: 8 hours,
Atmosphere: in the air.

Firing conditions Temperature rising rate: 200C / hour,
Holding temperature: 1220 ° C,
Temperature holding time: 2 hours,
Cooling rate: 300 ° C./hour,
Atmospheric gas: humidified N ₂ + H ₂ mixed gas,
Oxygen partial pressure: ^10-12 atm.

Annealing conditions Holding temperature: 1050C,
Temperature holding time: 2 hours,
Cooling rate: 300 ° C./hour,
Atmospheric gas: humidified N ₂ gas,
Oxygen partial pressure: 10 ⁻⁵ atm.

  In addition, a wetter with a water temperature of 20 ° C. was used for humidifying each atmospheric gas during the binder removal, firing and annealing.

External electrode After polishing the end face of the fired body by sand blasting, the external electrode transfers the external electrode paste to the end face, and fires at 800 ° C. for 10 minutes in a humidified N ₂ + H ₂ atmosphere. Was formed.

  The size of each sample thus obtained is 3.2 mm × 1.6 mm × 0.6 mm, the number of dielectric layers sandwiched between internal electrode layers is 4, and the thickness is shown in Table 2. As shown, the thickness was about 1.3 μm, and the thickness of the internal electrode layer was 1.2 μm. The average crystal grain size of the dielectric layer was 0.2 to 0.3 μm as shown in Table 2.

Moreover, the following characteristics were evaluated about each sample.

Molar ratio The main component molar ratio (Ba / Ti) and the final molar ratio (Ba / Ti) were measured by a glass bead method with X-ray fluorescence (Rigaku Denki 3550). The acceleration voltage was 40 kV. The results are shown in Tables 1 and 2.

Relative permittivity (ε), dielectric loss (tan δ), insulation resistance (IR)
Capacitance and dielectric loss are measured with a digital LCR meter (YHP 4272A) on a capacitor sample at a frequency of 120 Hz and an input signal level (measurement voltage) of 0.625 Vrms / μm. did. Then, the relative dielectric constant was calculated from the obtained capacitance. Thereafter, the insulation resistance (IR) after applying DC 20V to the capacitor sample for 60 seconds at 20 ° C. was measured using an insulation resistance meter (R8340A manufactured by Advantest Corporation). These results are shown in Table 2.

Capacitance temperature characteristics (TC)
The capacitance of the capacitor sample was measured with a digital LCR meter (YHP 4272A) under the conditions of a frequency of 120 Hz and an input signal level (measurement voltage) of 0.625 Vrms / μm. The change rate of capacitance at −25 and 85 ° C. was measured with respect to the capacitance when the reference temperature was 20 ° C. The results are shown in Table 2.

Capacitance bias characteristics (TC-Bias)
The capacitance of the capacitor sample was measured with a digital LCR meter (4272A manufactured by YHP) under the conditions of a frequency of 120 Hz, an input signal level (measurement voltage) of 0.625 Vrms / μm, and a reference temperature of 20 ° C. Using this capacitance as a reference, the capacitance is measured under the conditions of a frequency of 120 Hz, an input signal level (measurement voltage) of 0.625 Vrms / μm, a DC current of 2.5 V / μm, a measurement temperature of −25, and 85 ° C. The rate of change in capacitance was measured. The results are shown in Table 2.

Measurement of short-circuit failure The capacitor sample was measured with a multimeter (E2377A manufactured by HEWLETT PACKARD), and a short-circuit failure of 10Ω or less was determined. The measured parameter was 100. The results are shown in Table 2 and FIGS. 2A and 2B.

評価
表１および表２に示すように、チタン酸化物を後添加し、その添加量を所定範囲にすることで、誘電体層の厚みが１．５μｍ以下という超薄層の場合でも、容量温度変化率がＥＩＡＪ規格のＢ特性を満足し、しかも、比誘電率、誘電損失、絶縁抵抗などの電気特性に優れ、直流バイアス下での静電容量の変化率も少なく、ショート不良率も少ないコンデンサが得られることが確認できた。なお、表１および２において、試料番号２〜４が実施例であり、試料番号１および５〜１０が比較例である。 Breakdown voltage (VB)
A DC voltage was applied to the capacitor sample with an automatic booster (BTI-J118718S) at 50 V / s, and the voltage when the leakage current was 0.1 mA or more was defined as the breakdown voltage (VB). The results are shown in Table 2.

Evaluation As shown in Table 1 and Table 2, when the thickness of the dielectric layer is 1.5 μm or less by adding titanium oxide afterwards and making the addition amount within a predetermined range However, the rate of change in capacitance temperature satisfies the B characteristic of EIAJ standards, and it has excellent electrical characteristics such as relative permittivity, dielectric loss, and insulation resistance, and also has a low rate of change in capacitance under DC bias, resulting in short circuit failure. It was confirmed that a capacitor with a low rate was obtained. In Tables 1 and 2, sample numbers 2 to 4 are examples, and sample numbers 1 and 5 to 10 are comparative examples.

  Sample No. 1 is a comparative example because no titanium oxide is added, and the short-circuit defect rate is high. Moreover, in sample number 5, since the final molar ratio (Ba / Ti) is smaller than 1.004 because the addition amount of titanium oxide is too large, the short-circuit defect rate is high. In Sample No. 6, titanium oxide is added, but calcined together with other subcomponents and not added afterwards, so this is a comparative example, and this also has a high short-circuit defect rate.

  Sample Nos. 7 and 8 are low in the main component molar ratio from the beginning, but are comparative examples because no titanium oxide is added afterwards, and the short defect rate is high.

  Sample No. 9 uses a subcomponent containing titanium oxide, but is a comparative example because no calcining is performed and no titanium oxide is added afterwards, and the short-circuit defect rate is relatively high, and the breakdown voltage (VB) Is not preferable.

  In Sample No. 10, titanium oxide is added later, but since the main component molar ratio is less than 1 from the beginning, this is a comparative example, and the short defect rate is high, which is not preferable.

Example 2
FIG. 3 shows a cross-sectional photograph of the main part of the dielectric layer and the internal electrode layer in Sample No. 3 in Example 1. FIG. 4 shows a cross-sectional photograph of the dielectric layer using a scanning transmission electron microscope (STEM).

The grain boundaries of the crystal grains in the dielectric layer are a few so that the distance from the internal electrode entering the 0.015 μm dielectric layer to the middle of the dielectric layer is about 0.06 μm at a linear distance from the internal electrode. At points (reference numerals 1 to 11 in FIG. 4), each element of Ba, Ca, Mg, Mn, Si, Ti, V, Y, and Ni was detected, and the average was obtained. Furthermore, the molar ratio (Ba / Ti) between barium and titanium at the grain boundary was also determined. The results are shown in Table 3. In addition, those measurement points (reference numerals 1 to 11 in FIG. 4) are the grain boundaries of different phases containing 20 wt% of yttrium in terms of Y ₂ O ₃ and 15 wt% or more of silicon in terms of SiO ₂ in the grains. These are several points (reference numerals 1 to 11 in FIG. 4).

表３に示すように、試料番号２および３では、誘電体層の粒界には、ニッケルがＮｉＯに換算して０．９重量％以下、さらに好ましくは０．７重量％以下の割合で含まれ、マンガンがＭｎＯに換算して、好ましくは０．３５重量％以下、さらに好ましくは０．２３重量％以下の割合で含まれ、イットリウムがＹ_２Ｏ_３に換算して、３．５重量％以下、さらに好ましくは３．２重量％以下の割合で含まれ、チタンがＴｉＯ_２に換算して、３２重量％以上、さらに好ましくは３４重量％以上の割合で含まれる。また、誘電体層の粒界には、シリコンをＳｉＯ_２に換算して、好ましくは４．７重量％以下、さらに好ましくは４．０重量％以下の割合で含まれる。また、誘電体層２のバリウムとチタンの比Ａ／Ｂ（Ｂａ／Ｔｉ）が好ましくは０．９５以下、さらに好ましくは０．８０以下になっている。本発明の製造方法で得られる誘電体層における粒界には、内部電極からのニッケルの拡散が少なくなり、また、ＭｎＯ，Ｒ_２Ｏ_３，ＳｉＯ_２成分の粒界濃度が減り、ＴｉＯ_２成分の粒界濃度が増加する。このためショート不良率が低下し、ＶＢの低下を抑制すると考えられる。 Similarly, for sample numbers 1 and 2 in Example 1, each element of Ba, Ca, Mg, Mn, Si, Ti, V, Y, and Ni was detected, and the average was obtained. Furthermore, the molar ratio (Ba / Ti) between barium and titanium at the grain boundary was also determined. The results are shown in Table 3.

As shown in Table 3, in sample numbers 2 and 3, nickel is contained in the grain boundary of the dielectric layer in a proportion of 0.9% by weight or less, more preferably 0.7% by weight or less in terms of NiO. Manganese is preferably contained in an amount of 0.35% by weight or less, more preferably 0.23% by weight or less in terms of MnO, and yttrium in an amount of 3.5% by weight in terms of Y ₂ O _3. Hereinafter, it is further preferably contained in a proportion of 3.2% by weight or less, and titanium is contained in a proportion of 32% by weight or more, more preferably 34% by weight or more in terms of TiO ₂ . In addition, silicon is contained in the grain boundary of the dielectric layer in a proportion of preferably 4.7% by weight or less, more preferably 4.0% by weight or less, in terms of SiO ₂ . Further, the ratio A / B (Ba / Ti) of barium to titanium of the dielectric layer 2 is preferably 0.95 or less, more preferably 0.80 or less. In the grain boundary in the dielectric layer obtained by the production method of the present invention, the diffusion of nickel from the internal electrode is reduced, the grain boundary concentration of MnO, R ₂ O ₃ and SiO ₂ components is reduced, and the TiO ₂ component is reduced. Grain boundary concentration increases. For this reason, it is considered that the short-circuit defect rate is reduced and the decrease in VB is suppressed.

Example 3
Except for the thickness of the dielectric layer (interlayer thickness) being about 0.9 μm, the amount of post-addition of titanium oxide to the calcined powder was changed or titanium oxidation was performed in the same manner as in Example 1. The product was added to the pre-calcined powder and the relationship with the short-circuit defect rate was determined. The results are shown in Table 4 and FIGS. 5A and 5B. Sample numbers 11 to 19 in this example correspond to sample numbers 1 to 9 in example 1, and the dielectric layers are produced under the same conditions except that the interlayer thickness is different.

  As shown in Table 4 and FIG. 5, even in the case of an ultra-thin layer having a dielectric layer thickness of 1.0 μm or less, the sample numbers 12 to 14 are compared with the comparative examples shown in sample numbers 11 and 15 to 19. In the example shown, it was confirmed that a capacitor with a low short-circuit defect rate was obtained.

Example 4
Cr ₂ O ₃ is used instead of MnO, Dy ₂ O ₃ or Ho ₂ O ₃ is used instead of Y ₂ O ₃ , and WO ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ are used instead of V ₂ O _5. In the same manner as in Example 1 except that SrO was used instead of BaO or CaO, titanium oxide was post-added to the calcined powder, and the relationship with the short-circuit defect rate was determined. The results are shown in Table 5 and Table 6.

As shown in Tables 5 and 6, it was confirmed that the same results as in Example 1 were obtained even when these oxides were used.

FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention. FIG. 2A is a graph showing the effect of post-added titanium oxide in one example of the present invention. FIG. 2B is a graph in which the horizontal axis of FIG. 2A is expressed as final A / B. FIG. 3 is a photograph showing a cross-section of the main part of the multilayer ceramic capacitor obtained by the manufacturing method according to the example of the present invention. FIG. 4 is a photograph of a cross section of the main part of the multilayer ceramic capacitor obtained by the manufacturing method according to the example of the present invention, taken with a scanning transmission electron microscope. FIG. 5A is a graph showing the effect of post-added titanium oxide in another embodiment of the present invention. FIG. 5B is a graph in which the horizontal axis of FIG. 5A is expressed as final A / B.

Explanation of symbols

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

Claims (17)

Mixing at least part of the subcomponents and preparing a powder before calcining;
A step of calcining the pre-calcined powder to prepare a calcined powder;
A step of mixing the calcined powder with at least a main component having barium titanate and a titanium compound, followed by firing to obtain a dielectric ceramic composition, comprising: ,
The main component molar ratio (Ba / Ti) of barium and titanium in the main component barium titanate is 1 or more, and the final molar ratio (Ba / Ti) of barium and titanium in the final dielectric ceramic composition is The titanium compound is added so as to be 1.004 to 1.021, followed by main firing, and a method for producing a dielectric ceramic composition. The method for producing a dielectric ceramic composition according to claim 1, wherein the titanium compound is added so that the final molar ratio (Ba / Ti) is 1.006 to 1.019. As the other accessory component,
Selected from magnesium compounds, yttrium compounds, scandium compounds, europium compounds, gadolinium compounds, dysprosium compounds, holmium compounds, erbium compounds, thulium compounds, ytterbium compounds, lutetium compounds, terbium compounds, barium compounds, strontium compounds and calcium compounds At least one,
At least one selected from a silicon compound, a manganese compound, a chromium compound, a vanadium compound, a molybdenum compound, a tungsten compound, a niobium compound, and a tantalum compound is mixed with the pre-calcined powder and calcined. Item 3. A method for producing a dielectric ceramic composition according to Item 1 or 2. The main component barium titanate is BaTiO ₃ , the magnesium compound is MgO, the yttrium compound is Y ₂ O ₃ , the scandium compound is Sc ₂ O ₃ , the europium compound is Eu ₂ O ₃ , and the gadolinium compound is Gd. ₂ O ₃ , dysprosium compound in Dy ₂ O ₃ , holmium compound in Ho ₂ O ₃ , erbium compound in Er ₂ O ₃ , thulium compound in Tm ₂ O ₃ , ytterbium compound in Yb ₂ O ₃ to, lutetium compound _Lu 2 _{O 3,} terbium compound _Tb 2 _{O 3,} barium compound BaO, strontium compound SrO, a calcium compound to CaO, the silicon compound SiO _2, a manganese compound to MnO, The chromium compound is Cr ₂ O ₃ , and the vanadium compound is V ₂ O _5. When the molybdenum compound is converted to MoO ₃ , the tungsten compound is converted to WO ₃ , the niobium compound is converted to Nb ₂ O ₅ , and the tantalum compound is converted to Ta ₂ O ₅ , respectively.
BaTiO ₃ : The ratio to 100 mol is
MgO: 0.1-3 mol,
Y ₂ O ₃ , Sc ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Yb ₂ O ₃ , Lu ₂ O ₃ , Or Tb ₂ O ₃ : more than 0 mol and 5 mol or less,
BaO + CaO + SrO: 0.2-12 mol,
SiO _2: 0.2~12 mol,
MnO or Cr ₂ O ₃ : more than 0 mol and 1.0 mol or less,
_{V 2 O 5, MoO 3,} WO 3, Nb 2 O 5 or _Ta 2 _O 5,: _0~0.3 mol,
4. The dielectric according to claim 3, wherein the pre-calcination powder is prepared and calcined so that V ₂ O ₅ + MoO ₃ + WO ₃ + Nb ₂ O ₅ + Ta ₂ O ₅ exceeds 0 mol. A method for producing a body porcelain composition. The dielectric ceramic composition according to any one of claims 1 to 4, wherein the calcined powder is mixed with barium titanate and titanium oxide, which are main components, and then calcined. Manufacturing method. The titanium compound is added to the calcined powder in terms of BaTiO ₃ : 100 mol in terms of TiO ₂ , and is added in an amount of 0.1 to 1.8 mol, followed by main firing. Item 5. A method for producing a dielectric ceramic composition according to any one of Items 1 to 4. The method for producing a dielectric ceramic composition according to claim 1, wherein substantially no titanium oxide is added to the pre-calcined powder. A dielectric layer is formed using the dielectric ceramic composition obtained by the method according to any one of claims 1 to 6, wherein the dielectric layer-containing electronic component is produced. The method for producing a dielectric layer-containing electronic component according to claim 8, wherein the dielectric layer has a thickness of 4.5 μm or less. A dielectric layer-containing electronic component produced by the method according to claim 8 or 9. The dielectric layer-containing electronic component according to claim 10, wherein the dielectric layer is sandwiched between electrode layers containing nickel or a nickel alloy. The dielectric layer-containing electronic component according to claim 11, wherein nickel is contained in the grain boundary of the dielectric layer in a proportion of 0.9 wt% or less in terms of NiO. 13. The dielectric layer-containing electron according to claim 11, wherein the grain boundary of the dielectric layer contains manganese and / or chromium in a ratio of 0.35 wt% or less in terms of MnO or Cr ₂ O _3. parts. Wherein the dielectric layer of the grain boundary, the dielectric layer according to any one of claims 11 to 13 rare earth contained in a ratio of to 3.5 wt% or less in terms of the rare earth oxide (R 2 _{O 3)} Contains electronic components. The dielectric layer-containing electronic component according to claim 11, wherein titanium is contained in the grain boundary of the dielectric layer in a proportion of 32 wt% or more in terms of TiO ₂ . The dielectric layer-containing electronic component according to claim 11, wherein silicon is contained in the grain boundary of the dielectric layer in a ratio of 4.7% by weight or less in terms of SiO ₂ . The dielectric layer-containing electronic component according to claim 11, wherein a ratio A / B (Ba / Ti) of barium to titanium at a grain boundary of the dielectric layer is 0.95 or less.

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