JP6451406B2 - Dielectric composition - Google Patents

Description

  The present invention relates to a dielectric composition, and more particularly, to an electronic component used in a high temperature region such as in-vehicle use.

  For example, multilayer ceramic capacitors are used in many electronic devices because of their high reliability and low cost. Among them, there are those that guarantee operation at a high temperature such as 125 ° C. or 150 ° C., and are mainly used in vehicles. In recent years, there is a tendency that further high temperature guarantees are required for electronic devices used in vehicles. Therefore, a multilayer ceramic capacitor that can be used even in a high temperature region of 200 ° C. or higher is required.

It is desirable that the dielectric composition that guarantees operation at such a high temperature has a characteristic that the change in capacitance with respect to temperature (capacitance change rate) is small and the specific resistance does not decrease.
In addition, since the withstand voltage does not decrease in a high temperature environment, there is a tendency to increase the space between the internal electrodes. However, in order to increase the capacity of the multilayer ceramic capacitor, a dielectric composition independent of the thickness is required.
That is, a dielectric composition of a multilayer ceramic capacitor that guarantees operation at high temperatures needs to have a small capacitance change rate, a high specific resistance, and a high relative dielectric constant.

The smaller dielectric capacity change rate, Patent Document _{1 ((Ca x Sr 1-} x) O) m ((Ti y Zr 1-y) O 2), 0 ≦ x ≦ 1,0 ≦ y ≦ 0 10 and 0.75 ≦ m ≦ 1.04 are disclosed.

  However, the ceramic composition has a low relative dielectric constant of about 29 to 45 and has a problem that a desired capacity cannot be obtained.

  In Patent Document 2, in the three-component composition of CaO, TiO2, and SiO2, a part of TiO2 is replaced with one or more components selected from the group consisting of SnO2, MnO2, and ZrO2. A porcelain composition comprising a composition is disclosed.

  However, the above-mentioned porcelain composition relates to a dielectric material having a large dielectric loss tangent (tan δ) in the millimeter wave frequency band, and does not disclose any dielectric characteristics under a high temperature environment.

Japanese Patent Laid-Open No. 10-335169 JP 2002-293616 A

  The present invention has been made in view of the above problems, and provides a dielectric composition and an electronic component that have a low capacitance change rate, a high specific permittivity, and a high specific resistance under a high temperature environment.

In order to achieve the above object, in the dielectric composition according to the present invention, the main component is represented by the general formula CaTi _1-a Zr _a SiO ₅ , and a is 0.1 ≦ a ≦ 0.3. It is characterized by that.

  By satisfying the above range, the dielectric composition of the present invention has a small capacitance change rate and a high specific permittivity and high specific resistance.

  It has a first subcomponent containing at least one element selected from Mn and Co, and the first subcomponent is 0 mol ≦ first subcomponent ≦ 10 mol with respect to 100 mol of the main component. It is preferable.

  The dielectric composition of the present invention has a high specific resistance by having the above configuration.

  It is preferable that the second subcomponent includes Mg, and the second subcomponent satisfies 0 mol ≦ second subcomponent ≦ 10 mol with respect to 100 mol of the main component.

  Since the dielectric composition of the present invention has the above configuration, a small capacity change rate can be obtained.

  A third subcomponent containing at least one element selected from V, Nb, and Ta, and the third subcomponent is 0 mol ≦ third subcomponent ≦ 10 mol with respect to 100 mol of the main component; It is preferable that

  Since the dielectric composition of the present invention has the above configuration, a small capacity change rate can be obtained.

  A fourth subcomponent containing an element of R (where R is at least one element selected from rare earth elements), and the content of the fourth subcomponent is 0 with respect to 100 mol of the main component; It is preferable that mol ≦ fourth subcomponent ≦ 10 mol.

  Since the dielectric composition of the present invention has the above configuration, a small capacity change rate can be obtained.

  The fourth subcomponent is preferably Y, Gd, Tb, Dy, or Ho.

  Since the dielectric composition of the present invention has the above configuration, a small capacity change rate can be obtained.

  A fifth subcomponent containing at least one element selected from Si, Li, B, and Al, and the content of the fifth subcomponent is 0 mol ≦ 5th with respect to 100 mol of the main component; It is preferable that subcomponents ≦ 20 mol.

  The dielectric composition of the present invention has a high specific resistance by having the above configuration.

  The application of the electronic component having a dielectric layer made of the dielectric composition according to the present invention is not particularly limited, but is useful for a multilayer ceramic capacitor, a piezoelectric element, a chip varistor, a chip thermistor, a thin film capacitor, and the like.

  Since the dielectric composition according to the present invention has a small capacitance change rate and a high relative dielectric constant and specific resistance, a dielectric composition and an electronic component that can be used at high temperatures can be provided.

Sectional drawing of the multilayer ceramic capacitor which concerns on one Embodiment of this invention Graph of capacity change rate from 25 ° C. to 250 ° C. of dielectric compositions of Example 1 and Comparative Example 1

  Hereinafter, embodiments of the present invention will be described.

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

  The thickness of the dielectric layer 2 is not particularly limited, and may be appropriately determined according to the use of the multilayer ceramic capacitor 1.

  The conductive material contained in the internal electrode layer 3 is not particularly limited, but Ni, Pd, Ag, Pd—Ag alloy, Cu or Cu-based alloy is preferable. The Ni, Pd, Ag, Pd—Ag alloy, Cu, or Cu-based alloy may contain various trace components such as P or the like in an amount of about 0.1% by weight or less. The internal electrode layer 3 may be formed using a commercially available electrode paste. What is necessary is just to determine the thickness of the internal electrode layer 3 suitably according to a use etc.

The dielectric layer 2 is represented by CaTi _1-a Zr _a SiO ₅ , wherein a is a dielectric composition in which 0.1 ≦ a ≦ 0.3.

  The content of Zr is 0.1 to 0.3 mol, preferably 0.15 to 0.25. When the content of Zr is too small, the capacity change rate increases and the specific resistance decreases. If the content of Zr is too large, the relative dielectric constant will decrease.

The content of at least one element selected from M n and Co is 0 to 10 mol, preferably 0.1 to 5 mol, per 100 mol of CaTi _1-a Zr _a SiO ₅ . These elements have the effect of increasing the specific resistance. When these contents are too large, the relative dielectric constant is lowered.

The content of Mg is 0 to 10 mol, preferably 0.1 to 5 mol, per 100 mol of CaTi _1-a Zr _a SiO ₅ . Mg has the effect of reducing the capacity change rate. If the content of Mg is too large, the relative dielectric constant will decrease.

The content of at least one element selected from V, Nb, and Ta is 0 to 10 mol, preferably 0.1 to 5 mol, per 100 mol of CaTi _1-a Zr _a SiO ₅ . These elements have the effect of reducing the capacity change rate. When these contents are too large, the specific resistance is lowered.

The content of R is 0 to 10 mol, preferably 0.1 to 5 mol, per 100 mol of CaTi _1-a Zr _a SiO ₅ . These elements have the effect of reducing the capacity change rate. When these contents are too large, the specific resistance is lowered. As the element of R, Y, Gd, Tb, Dy and Ho are preferable.

The content of at least one element selected from Si, Li, B and Al is 0 to 20 mol, preferably 0.1 to 5 mol, per 100 mol of CaTi _1-a Zr _a SiO _5. is there. These elements have the effect of increasing the specific resistance. When these contents are too large, the relative dielectric constant is lowered.

In the present specification, CaTi _1-a Zr _a SiO ₅ is represented by a stoichiometric composition, but may deviate from the stoichiometric composition.

  Next, an example of a method for manufacturing the multilayer ceramic capacitor shown in FIG. 1 will be described.

  In the multilayer ceramic capacitor 1 of this embodiment, a green chip is produced by a normal printing method or a sheet method using a paste, and fired, and then printed or transferred an external electrode, similarly to a conventional multilayer ceramic capacitor. It is manufactured by baking. Hereinafter, the manufacturing method will be specifically described.

First, raw materials are prepared and mixed so that the general formula CaTi _1-a Zr _a SiO ₅ has a desired ratio, and heat treatment (preliminary firing) is performed at 800 ° C. or higher to obtain calcined powder.

As the raw material, an oxide mainly composed of Ca, Ti, Zr, and Si or a mixture thereof can be used as the raw material powder. Furthermore, various compounds that become the above-described oxides or composite oxides by firing, for example, carbonates, oxalates, nitrates, hydroxides, organometallic compounds, and the like can be appropriately selected and mixed for use. Specifically, CaO may be used as a Ca raw material, or CaCO ₃ may be used.

As a raw material for the subcomponent, an oxide of the subcomponent or a mixture thereof can be used as the raw material powder. Furthermore, various compounds that become the above-described oxides or composite oxides by firing, for example, carbonates, oxalates, nitrates, hydroxides, organometallic compounds, and the like can be appropriately selected and mixed for use. Specifically, MgO may be used as a raw material for Mg, or MgCO ₃ may be used.

  The dielectric composition raw material is prepared by mixing and drying the calcined powder of the main component and the raw material powder of the subcomponent. Further, the mixing of the calcined powder of the main component and the raw material powder of the subcomponent may be performed at the time of forming a paint described later.

  The dielectric composition raw material 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 material and an organic vehicle, or may be a water-based paint.

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

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

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

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

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

  When the printing method is used, the dielectric layer paste and the internal electrode layer paste are printed and laminated 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. As binder removal conditions, the rate of temperature rise is preferably 5 to 300 ° C./hour, the holding temperature is preferably 180 to 500 ° C., and the temperature holding time is preferably 0.5 to 24 hours. The firing atmosphere is air or a reducing atmosphere.

  Moreover, the holding temperature at the time of baking becomes like this. Preferably it is 1000-1400 degreeC, More preferably, it is 1100-1360 degreeC. If the holding temperature is lower than the above range, the densification becomes insufficient. If the holding temperature exceeds the above range, the electrode is interrupted due to abnormal sintering of the internal electrode layer, or the capacity change rate is deteriorated due to diffusion of the constituent material of the internal electrode layer. It becomes easy.

  As other firing conditions, the rate of temperature rise is preferably 50 to 500 ° C./hour, more preferably 200 to 300 ° C./hour, and the temperature holding time is preferably 0.5 to 24 hours, more preferably 1 to 3 hours. The time and cooling rate are preferably 50 to 500 ° C./hour, more preferably 200 to 300 ° C./hour.

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

  The capacitor element main body obtained as described above is subjected to end face polishing, for example, by barrel polishing or sand blasting, and the external electrode paste is applied and fired to form the external electrode 4. Then, if necessary, a coating layer is formed on the surface of the external electrode 4 by plating or the like.

  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.

  EXAMPLES Hereinafter, although the specific Example of this invention is given and this invention is demonstrated further in detail, this invention is not limited to these Examples.

As raw materials for the main components, CaCO ₃ , TiO ₂ , ZrO ₂ , and SiO ₂ powders were prepared.

  These were weighed so that the main component composition was as shown in Table 1, wet-mixed with a ball mill, and then dried to obtain mixed powders. And these mixed powder was calcined at 800 degreeC, and the calcined powder was obtained.

  Next, separately from the above, raw materials for the first to fifth subcomponents were prepared so that the subcomponents were as shown in Table 1. In addition, the addition amount of these 1st-5th subcomponents is an addition amount with respect to 100 mol of main components.

  Next, the calcined powder and the first to fifth subcomponent raw materials were weighed, mixed, and dried to prepare a dielectric composition raw material.

  Dielectric composition raw material thus obtained: 100 parts by weight, polyvinyl butyral resin: 10 parts by weight, dibutyl phthalate (DOP) as a plasticizer: 5 parts by weight, and alcohol as a solvent: 100 parts by weight Were mixed with a ball mill to form a paste, and a dielectric layer paste was prepared.

  In addition to the above, Pd particles: 44.6 parts by weight, terpineol: 52 parts by weight, ethyl cellulose: 3 parts by weight, and benzotriazole: 0.4 parts by weight are kneaded by three rolls to form a slurry. To prepare an internal electrode layer paste.

  And the green sheet was formed on the PET film so that the thickness after drying might be set to 7 micrometers using the produced dielectric layer paste. Next, the internal electrode layer was printed in a predetermined pattern using the internal electrode layer paste thereon, and then the sheet was peeled from the PET film to produce a green sheet having the internal electrode layer. Next, a plurality of green sheets having internal electrode layers were laminated and pressure-bonded to form a green laminate, and the green laminate was cut into a predetermined size to obtain a green chip.

  Next, the obtained green chip was subjected to binder removal treatment (temperature rising rate: 10 ° C./hour, holding temperature: 400 ° C., temperature holding time: 8 hours, atmosphere: in air), and fired (temperature rising rate: 200). C./hour, holding temperature: 1000 to 1400.degree. C., temperature holding time: 2 hours, cooling rate: 200.degree. C./hour, atmosphere: in air) to obtain a multilayer ceramic fired body.

  Next, after polishing the end face of the obtained multilayer ceramic fired body by sandblasting, an In—Ga eutectic alloy was applied as an external electrode, and Examples 1 to 23 having the same shape as the multilayer ceramic capacitor shown in FIG. The multilayer ceramic capacitors of Examples 1 to 12 were obtained. The size of the obtained multilayer ceramic capacitor is 3.2 mm × 1.6 mm × 1.2 mm. The thickness of the dielectric layer is 5.0 μm, the thickness of the internal electrode layer is 1.5 μm, and it is sandwiched between the internal electrode layers. The number of dielectric layers was 10.

For the obtained multilayer ceramic capacitors of Examples 1 to 23 and Comparative Examples 1 to 12, the relative dielectric constant (ε _s ), the change in capacitance with respect to temperature (capacitance change rate), and the specific resistance were measured by the following methods. did.

[Relative permittivity (ε _s )]
A signal having a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms was input to the multilayer ceramic capacitor with a digital LCR meter (4284A manufactured by YHP) at 25 ° C., and the capacitance C was measured. Then, the relative dielectric constant ε _s (no unit) was calculated based on the thickness of the dielectric layer, the effective electrode area, and the capacitance C obtained as a result of the measurement. The results are shown in Table 1. A higher relative dielectric constant is preferable, and a value of 55 or higher was judged to be good.

[Capacitance temperature characteristics]
Capacitance was measured at 250 ° C with a digital LCR meter (YHP 4284A) at a frequency of 1 kHz and an input signal level (measurement voltage) of 1 Vrms. The change rate (capacity change rate) with respect to was calculated. The absolute value of the rate of change is preferably low, and it is judged that the value within ± 3.0% is good.

[Resistivity]
The insulation resistance of the capacitor sample was measured at 250 ° C. with a digital resistance meter (R8340 manufactured by ADVANTEST) under the conditions of a measurement voltage of 20 V and a measurement time of 60 seconds. The specific resistance value was calculated from the electrode area and the dielectric thickness of the capacitor sample. The specific resistance is preferably as high as possible, and 2 × 10 ¹¹ Ωcm or more was judged to be good. If the specific resistance is low, the leakage current of the capacitor becomes large, causing malfunction in the electric circuit.

  By comparing Examples 1 to 3 with Comparative Examples 1 and 2, when the Zr content of the dielectric composition is 0.1 or more and 0.3 or less, the relative permittivity is high and the capacitance change rate is high. Is small and the specific resistance is high. In Comparative Example 1, since the Zr content was 0.05, the capacity change rate was poor and the specific resistance was low. In Comparative Example 2, since the Zr content was 0.35, the relative dielectric constant was low and the specific resistance was low.

Further, by comparing Example 2 and Examples 4 to 7, when the content of Mn of the first subcomponent is 0 mol or more and 10 mol or less, the relative dielectric constant is high and the capacity change rate is small. It can be seen that the specific resistance is high. In Example 7, since the Mn content was 11 mol, the relative dielectric constant was low.

  Further, by comparing Example 2 and Examples 8 to 11 (Examples), when the content of Mg as the second subcomponent is 0 mol or more and 10 mol or less, the relative dielectric constant is high and the capacitance change It can be seen that the ratio is small and the specific resistance is high. In Example 11, since the Mg content was 11 mol, the relative dielectric constant was low.

  Further, by comparing Example 2 and Examples 12 to 15 (Examples), when the content of V of the third subcomponent is 0 mol or more and 10 mol or less, the relative dielectric constant is high and the capacitance change It can be seen that the ratio is small and the specific resistance is high. In Example 15, the specific resistance was low because the V content was 11 mol.

  Further, by comparing Example 2 and Examples 16 to 19 (Examples), when the Y content of the fourth subcomponent is 0 mol or more and 10 mol or less, the relative dielectric constant is high and the capacitance change It can be seen that the ratio is small and the specific resistance is high. In Example 19, since the Y content was 11 mol, the specific resistance was low.

  Further, by comparing Example 2 and Examples 20 to 23 (Examples), when the content of Si as the fifth subcomponent is 0 mol or more and 20 mol or less, the relative dielectric constant is high and the capacitance change It can be seen that the ratio is small and the specific resistance is high. In Example 23, since the Y content was 21 mol, the relative dielectric constant was low.

Except that Co was used as a substitute for Mn, Nb or Ta was used as a substitute for V, Gd, Tb, Dy or Ho was used as a substitute for Y, and Li, B or Al was used as a substitute for Si Capacitor samples were prepared in the same manner as in Examples 1 to 23 and evaluated in the same manner. Table 2 shows each subcomponent type and evaluation results. The second subcomponent Mg was mol.

  As shown in Table 2, Co is used as a substitute for Mn, Nb or Ta is used as a substitute for V, Gd, Tb, Dy, or Ho is used as a substitute for Y, and Li, B are used as substitutes for Si. It was confirmed that similar characteristics were obtained even when Al was used.

  From these, it was confirmed that by setting the composition of the dielectric composition within the predetermined range of the present invention, a high relative dielectric constant and a small capacity change rate can be obtained.

  Further, the dielectric constant of the sample of Example 1 was measured by changing the temperature in the range of 25 ° C. to 250 ° C. The measurement results are shown in FIG. 2 together with the change in capacity ratio of Comparative Example 1.

  From FIG. 2, it can be seen that in the comparative example, the change in capacitance is large when the temperature is changed, whereas the sample having the dielectric composition according to the present invention has a small change in capacitance with respect to the temperature.

  Since the temperature characteristics are flat in a wide temperature range, it can be applied as a vehicle-mounted dielectric element, electronic component, and laminated electronic component in a high-temperature environment such as the vicinity of an engine room.

The present invention can also be applied to a thin film capacitor having a dielectric film composed of the dielectric composition of the present invention.

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

Claims (7)

The main component is represented by the general formula CaTi _1-a Zr _a SiO ₅ , a is 0.1 ≦ a ≦ 0.3 ,
The content of the element that has the first subcomponent including at least one element selected from Mn and Co and is at least one selected from Mn and Co is 100 mol of CaTi _1-a Zr _a SiO _5. The dielectric composition is characterized in that the amount is 0.1 to 5 moles . The main component is represented by the general formula CaTi _1-a Zr _a SiO ₅ , a is 0.1 ≦ a ≦ 0.3 ,
A dielectric composition comprising a second subcomponent including Mg, wherein the content of Mg is 0.1 to 5 mol with respect to 100 mol of CaTi _1-a Zr _a SiO ₅ . The main component is represented by the general formula CaTi _1-a Zr _a SiO ₅ , a is 0.1 ≦ a ≦ 0.3 ,
It has a third subcomponent containing at least one element selected from V, Nb and Ta, and the content of at least one element selected from V, Nb and Ta is CaTi _1-a Zr _a SiO _{5 A} dielectric composition characterized by being 0.1 to 5 moles per 100 moles . The main component is represented by the general formula CaTi _1-a Zr _a SiO ₅ , a is 0.1 ≦ a ≦ 0.3 ,
It has a fourth subcomponent containing an element of R (where R is at least one element selected from rare earth elements), and the content of R is 100 mol of CaTi _1-a Zr _a SiO ₅ . A dielectric composition characterized by being 0.1 to 5 moles . The dielectric composition according to claim 4 , wherein the element of R is at least one selected from Y, Gd, Tb, Dy and Ho. The main component is represented by the general formula CaTi _1-a Zr _a SiO ₅ , a is 0.1 ≦ a ≦ 0.3 ,
It has a fifth subcomponent containing at least one element selected from Si, Li, B and Al, and the content of at least one element selected from Si, Li, B and Al is CaTi _{1 − A} dielectric composition characterized by being 0.1 to 5 moles per 100 moles of _a Zr _a SiO ₅ . Electronic device comprising a dielectric layer comprising a dielectric composition according to any one of claims 1 to 6.

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