JP2006273698A - Dielectric ceramic composition containing barium titanate as main component and dielectric ceramic capacitor using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lead-free dielectric ceramic composition containing barium titanate as a main component, which satisfies all the characteristics including smooth temperature characteristics, high dielectric permittivity, low self-heating or the like. <P>SOLUTION: The dielectric ceramic composition containing barium titanate as the main component is a solid solution composition forming a perovskite-type structure, containing BiMnO<SB>3</SB>of 1.0 mole percent to 2.0 mole percent, Ba<SB>1/2</SB>NbO<SB>3</SB>or Ba<SB>1/2</SB>TaO<SB>3</SB>of 0.3 mole percent to 1.2 mole percent, and Bi<SB>2/3</SB>TiO<SB>3</SB>of 9.0 mole percent to 15.0 mole percent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a dielectric ceramic composition mainly composed of barium titanate and a dielectric ceramic capacitor using the same, and more particularly to a lead-free dielectric ceramic composition for use in a medium-high voltage ceramic capacitor. .

  In recent years, environmental problems have been highlighted, and materials that do not contain environmentally hazardous substances are being studied for electronic components used in electronic devices. Among the materials used for electronic parts, lead (Pb) is particularly harmful to the environment. If lead is left undisturbed, it dissolves in the environment and adversely affects the living body. Therefore, development of lead-free electronic components is underway in the electronics industry.

One of the electronic parts is a dielectric ceramic capacitor for medium to high voltage, and this dielectric ceramic composition may contain lead. In particular, in order to achieve useful characteristics such as smooth temperature characteristics of capacitor capacity, high dielectric constant, low self-heating, etc., in the barium titanate solid solution, lead is used as PbTiO ₃ component as 10-20 mol% And very much.

However, if the PbTiO ₃ component is completely removed from the dielectric ceramic composition, it naturally satisfies all the characteristics such as the smoothness of the temperature characteristics of the capacitance, high dielectric constant, and low self-heating required for the medium- and high-voltage capacitors. It was not possible to obtain a dielectric ceramic composition.

  The present invention has been made in view of the above circumstances, and satisfies the characteristics required for a ceramic capacitor, such as a smooth temperature characteristic, a high dielectric constant, and a low self-heating, and is a dielectric containing no lead. The object is to provide a body porcelain composition.

In order to solve this problem, the present invention provides a solid solution composition that forms a perovskite structure mainly composed of barium titanate. In a solid solution composition composed mainly of BaTiO ₃ , the BiMnO ₃ component is added in an amount of 1.0 mol% to 2.0 mole%, containing Ba _1/2 NbO ₃ or Ba _1/2 3 to 4 components of TaO ₃ component 0.3 mol% to 1.2 mol% and Bi _2/3 TiO ₃ component 9.0 mol% to 15.0 mol% It is a composition composition.

  With this configuration, it is possible to obtain characteristics required for medium- and high-voltage ceramic capacitors, such as smooth capacitance temperature characteristics, high dielectric constant, and low self-heating without containing lead.

This is considered to be due to the following actions. First, the BiMnO ₃ component is the most important component contributing to the smoothing of the temperature characteristics of the capacitance, and at the same time has the effect of shifting the Curie point of BaTiO ₃ to the high temperature side. The BiMnO ₃ component shifts the Curie point of BaTiO ₃ to the high temperature side by 5.5 ° C. per 1 mol% content. However, when the content exceeds 2 mol%, the Curie point starts to shift to the low temperature side, and at the same time, the dielectric loss increases. Here, the lower limit of the BiMnO ₃ component is determined by the standard of the magnetic capacitor to be obtained, but is generally 1.0%.

Next, the Ba _1/2 NbO ₃ or Ba _1/2 TaO ₃ component contributes to reducing the dielectric loss (tand), and as a result, is the only important component having the effect of reducing self-heating. Ba _1/2 NbO ₃ and Ba _1/2 TaO ₃ have almost the same effect, and may be used alone or in combination. Ba _1/2 NbO ₃ and Ba _1/2 TaO ₃ both have the effect of shifting the Curie point of BaTiO ₃ to the low temperature side. However, the Ba _1/2 NbO ₃ component is shifted to the low temperature side by 20 ° C. per mol%, whereas the Ba _1/2 TaO ₃ component has the effect of shifting to the low temperature side by 26 ° C. per mol%. .

Furthermore, the Bi _2/3 TiO ₃ component plays a major role in shifting the Curie point of BaTiO ₃ to the low temperature side. It has the effect of shifting to 6.7 ° C low temperature per mol%. There are many components that act as low-temperature shifters. Among them, the Bi _2/3 TiO ₃ component contributes to smoothing the temperature characteristics of the capacitance, and also contributes to maintaining a relatively high dielectric constant. Furthermore, it has the effect of promoting the sintering to lower the sintering temperature of the porcelain composition to around 1200 ° C., contributing to energy saving in the manufacturing process.

The dielectric ceramic composition of the present invention has a solid solution composition containing BaTiO ₃ as a main component, BiMnO ₃ component being 1.0 mol% to 2.0 mol%, and Ba _1/2 NbO ₃ or Ba _1/2 TaO ₃ component being 0.3 mol%. % to 1.2 mol%, Bi _2/3 TiO ₃ component 9.0 mol% to 15.0 mol%, SrTiO ₃ component 1.0 mol% to 4.0 mol%, BaSnO ₃ component 0.5 mol% to 3.0 mol%, the BaZrO ₃ component It is a dielectric ceramic composition containing 0.1 mol% to 3.0 mol% and 88.0 mol% to 75.0 mol% of BaTiO ₃ component.

With this configuration, the Curie point is reduced without containing lead, and the characteristics required for medium- and high-voltage ceramic capacitors, such as smooth temperature characteristics, high dielectric constant, and low self-heating, are obtained. be able to.
According to this configuration, the Curie point (the temperature at which the dielectric constant shows the maximum value in the temperature change of the dielectric constant), which is one of the important factors in the material design of the dielectric ceramic composition, is about 15 ° C. around room temperature. Can be 20 ° C. Already mentioned 9.0 mol% to 15.0 mol% Bi _2/3 TiO ₃ component and 0.3 mol% to 1.2 mol% Ba _1/2 NbO ₃ or Ba _1/2 TaO ₃ component alone gives a Curie point of 15 ° C to 20 ° C. Of 1.0 mol% to 4.0 mol% SrTiO ₃ component, 0.5 mol% to 3.0 mol% BaSnO ₃ component and 0.1 mol% to 3.0 mol% BaZrO ₃ component as additional low temperature shifters The Curie point could be further reduced by selecting and adding the three components. The shift effect of each component to the low temperature side is 5 ° C./mol% for the SrTiO ₃ component, 7 ° C./mol% for the BaSnO ₃ component, and 4 ° C./mol% for the BaZrO ₃ component. Here, for the design of only the Curie point, it is sufficient to use one of these components. However, it is desirable to use as many components as possible from the viewpoint of smoothing the temperature characteristic of the capacitance.

The dielectric ceramic composition of the present invention is characterized in that 1.5 mol% or less of BaCO ₃ is added to a total amount of 100 mol% of a solid solution composition mainly composed of BaTiO ₃ .
With this configuration, the dielectric constant can be increased without containing lead, and characteristics such as smooth capacity temperature characteristics, high dielectric constant, and low self-heating are required for medium- and high-voltage ceramic capacitors. Can be obtained.
By adding an excessive amount of BaCO ₃ within the range of 1.5 mol% or less to this solid solution composition of 100 mol%, the sintering density is slightly increased while suppressing the grain growth of the porcelain, and the result. The dielectric constant can be increased by 5% to 10%. On the other hand, the addition of BaCO ₃ exceeding 1.5 mol% is undesirable because it decreases the dielectric constant.

The dielectric ceramic composition of the present invention is characterized in that 1.0% by mole or less of a Bi ₂ O ₃ component is added to a total amount of 100% by mole of a solid solution composition containing BaTiO ₃ as a main component.
With this configuration, a medium-high voltage ceramic capacitor having particularly smooth capacitance temperature characteristics can be obtained without containing lead, and characteristics such as a capacitance temperature characteristic being smooth, a high dielectric constant, and low self-heating can be obtained. be able to.
Adding excessive Bi ₂ O ₃ in the range of 1.0 mol% or less with respect to 100 mol% of the solid solution composition is slightly effective in smoothing the temperature characteristic of the capacity (particularly on the high temperature side). On the other hand, addition exceeding 1.0 mol% is undesirable because it causes a decrease in dielectric constant.

The dielectric ceramic composition of the present invention comprises a BiMnO ₃ component of 1.4 mol% to 1.8 mol%, a Ba _1/2 NbO ₃ or Ba _1/2 TaO ₃ component of 0.6 mol% to 0.9 mol%, Bi _2/3 TiO. ₃ ingredient 11.0 mol% to 13.0 mol%, SrTiO ₃ component 1.5 mol% to 2.5 mol%, BaSnO ₃ component 0.5 mol% to 1.5 mol%, BaZrO ₃ component 0.2 mol% to 0.5 mol%, and BaTiO ₃ adding BaCO ₃ components of 0.3 mol% to 1.0 mol% of BaTiO ₃ of a total of 100 mole%, characterized by comprising components from 7 component of 84.8 mol% ～79.8 mol% relative to the solid solution composition as a main component It is characterized by that.
With this configuration, it is possible to obtain characteristics required for the medium- and high-voltage ceramic capacitors, such as smooth capacity temperature characteristics, high dielectric constant, and low self-heating without containing lead.

  The dielectric ceramic capacitor of the present invention is obtained by using the dielectric ceramic composition as a dielectric substrate and sandwiching the dielectric substrate between the first and second electrodes, and having a smooth temperature characteristic and a large capacity. Can be obtained.

  As described above, according to the present invention, the dielectric ceramic composition containing no lead, satisfying all the characteristics, having a smooth temperature characteristic of dielectric constant, a high relative dielectric constant, and a low self-heating. And a medium- and high-voltage porcelain capacitor using the same. Here, the temperature characteristic is smooth, the rate of change of capacitance is ± 15% or less, the high relative dielectric constant is 1000 or more, and the low self-heating is about 40 ° C. or less.

  Thus, according to the present invention, characteristics equivalent to the material composition containing lead (Pb) can be obtained by the solid solution composition having a new perovskite structure.

  Hereinafter, embodiments of the present invention will be described in detail.

(Embodiment 1)
A ceramic capacitor using the dielectric ceramic composition of the present invention will be described as Embodiment 1 of the present invention.
FIG. 1A is a see-through side view showing the porcelain capacitor according to the first embodiment of the present invention, and FIG. 1B is a see-through front view showing the porcelain capacitor according to the first embodiment of the present invention. 1A and 1B, 1 is a dielectric ceramic substrate, 2 is a first layer electrode, 3 is a second layer electrode, 4, 5 are lead wires, and 6 is an exterior material. Reference numeral 100 denotes a porcelain capacitor.

  As shown in FIGS. 1A and 1B, a ceramic capacitor 100 has a first layer electrode 2 and a second layer electrode 3 formed on both main surfaces of a disk-type dielectric ceramic substrate 1, respectively. Further, a pair of lead wires 4 and 5 are soldered to the second layer electrode 3 respectively.

  And the exterior material 6 which embeds a part of lead wires 4 and 5 and the dielectric ceramic board | substrate 1, the 1st layer electrode 2, and the 2nd layer electrode 3 is formed.

  As the dielectric ceramic substrate 1, the above-described dielectric ceramic composition of the present invention is used.

  Similarly, at least one metal selected from Zn, Cu, Ni, Ag, Pd, and Al is used as the first layer electrode 2 and the second layer electrode 3. For the second layer electrode 3, it is only necessary to select a lead-free solder when joining the lead wires 4, 5 or a metal having a high adhesive strength with the solder, and only the first layer electrode 2 is provided without providing the second layer electrode 3. May be formed.

  Furthermore, as the lead wires 4 and 5, for example, a wire material obtained by using, as a raw material, an electrical copper wire specified in JIS C3102 and electroplating or melting solder can be used.

  Moreover, as the exterior material 6, an insulating material is used, and glass, an insulating resin, or the like can be used. Among these, the insulating resin is preferable because of its processing suitability and low price, the thermosetting resin is more preferable as it is excellent in processing suitability, and the thermosetting epoxy resin is particularly preferable because of its excellent strength and moisture resistance. Examples thereof include epoxy resins such as optocresol novolac, biphenyl, and pentadiene.

  Further, as shown in FIG. 1A, a pair of lead wires 4 and 5 joined to the second layer electrodes 3 on both main surfaces of the dielectric ceramic substrate 1 sandwich the dielectric ceramic substrate 1 therebetween. Although they are spaced apart and extend in parallel, they are bent and finally pulled out so as to overlap in the thickness direction of the dielectric ceramic substrate 1. The pair of lead wires 4 and 5 are overlapped at a position that is approximately half of the separation distance, that is, a position that makes the thickness of the dielectric ceramic substrate 1 approximately half.

  Further, as shown in FIG. 1B, the pair of lead wires 4 and 5 are respectively joined to the second layer electrode 3 so as to cross on the front and back surfaces of the dielectric ceramic substrate 1, bent, and substantially parallel. So as to be spaced apart from each other, and further bent so as to extend in parallel with the distance between the two narrowed.

  The pair of lead wires 4 and 5 of the porcelain capacitor 100 are inserted into the through holes of the circuit board and soldered and mounted on the back surface of the circuit board. As shown in FIG. By narrowing the distance at which the lead wires 4 and 5 are separated from each other at the insertion portion into the through hole, the portion where the separation distance between the lead wires 4 and 5 is increased acts as a stopper and the insertion portion is defined. In addition, all the portions of the lead wires 4 and 5 protruding from the exterior material 6 do not enter the through hole.

  In addition, since a part of the lead wires 4 and 5 is necessarily interposed between the lowermost part of the outer packaging material 6 of the ceramic capacitor 100 to be mounted and the circuit board, the solder flux is hardly affected by the soldering. Can be reliably discharged. And since it is hard to receive the influence of the heat | fever at the time of solder joining, lead (Pb) free solder with high soldering temperature can be used.

  Next, a method for manufacturing the ceramic capacitor according to Embodiment 1 of the present invention will be described.

  First, the materials constituting the dielectric porcelain composition are blended, wet-mixed or granulated by a conventional ceramic technique, pressed into a disk shape, and then fired. Will be described later.

  Then, for example, a Zn electrode is formed as a first layer electrode 2 on both main surfaces of the obtained dielectric ceramic substrate 1 by a printing method. Specifically, zinc paste is formed on both main surfaces of the dielectric ceramic substrate 1 by screen printing, and then baked at about 600 ° C. This baking need not be performed in a neutral or reducing atmosphere, and can be performed in an air atmosphere. As other methods for forming the Zn electrode, a so-called dip coating method in which a part is immersed in a conductive paste and coating methods such as an electrodeposition method, a plating method, and a vapor deposition method can be used.

  Further, the surface of the Zn electrode that is the first layer electrode 2 is activated. This surface activation treatment is to remove oxide on the surface of the Zn electrode. As a result, the adhesion of the second layer electrode 3 laminated on the upper layer to the electrode mainly composed of at least one metal selected from Cu, Ni, Ag, Pd, and Al is improved. An unstable metal compound is not generated between the two. As the Zn electrode surface activation treatment, chemical etching can be used, and is performed by using an acid. Specifically, for example, malic acid having a pH of about 3 is used. As another method, physical etching such as physically roughing the surface may be used.

  Next, for example, a Cu electrode is formed as the second layer electrode 3 on the Zn electrode which is the first layer electrode 2. The formation of the Cu electrode as the second layer electrode 3 is performed by a plating method. This plating may be either electrolytic plating or electroless plating, but electroless plating is preferable because it does not deteriorate ceramic element characteristics.

  Then, the lead wires 4 and 5 are soldered with lead-free solder or the like on the Cu electrode which is the second layer electrode 3, and a part of the lead wires 4 and 5 is removed and coated with an insulating resin or the like. A material 6 is formed.

(Embodiment 2)
In the first embodiment, the type of ceramic capacitor in which the lead terminal is inserted through the through-hole of the circuit board has been described. However, in the present embodiment, the mounting type ceramic capacitor will be described.
FIG. 2 is a cross-sectional view showing a surface-mounted ceramic capacitor according to Embodiment 2 of the present invention. In FIG. 2, 7 and 8 are lead terminals, and 200 is a surface-mounted ceramic capacitor. In addition, the same code | symbol is attached | subjected to the part similar to what was demonstrated in Embodiment 1. FIG.

  As shown in FIG. 2, the surface mount type ceramic capacitor 200 has a first layer electrode 2 and a second layer electrode 3 formed on both main surfaces of a disk-shaped dielectric ceramic substrate 1, respectively. A pair of lead terminals 7 and 8 are soldered to the layer electrode 3 respectively.

  The exterior material 6 embeds the dielectric ceramic substrate 1, the first and second layers of electrodes 2 and 3, and part of the lead terminals.

  Moreover, the part which protruded from the exterior material 6 of the lead terminals 7 and 8 comprises an external terminal formation part, and it can be surface-mounted on a circuit board via the external terminal formation part of this lead terminal 7 and 8. It has become.

  As the dielectric ceramic substrate 1, as described in the first embodiment, a dielectric ceramic mainly composed of the dielectric composition of the present invention is used. Similarly, the first layer electrode 2 and the second layer electrode are used. As 3, at least one metal selected from Zn, Cu, Ni, Ag, Pd, and Al is used.

  Further, the exterior material 6 is the same as that described in the first embodiment, and an insulating material is used, and glass, insulating resin, or the like can be used. The thermosetting resin is excellent in processing suitability and more preferable, and the thermosetting epoxy resin typified by an epoxy resin such as an optocresol novolak type, a biphenyl type, or a pentadiene type has high strength and moisture resistance. It is particularly preferable because it is excellent.

  As the lead terminals 7 and 8, a conductive material can be used, but a metal material selected from at least one of Fe, Cu, and Ni is preferably used, which is advantageous in terms of electrical characteristics and workability. .

Next, the method for manufacturing the surface-mount type ceramic capacitor according to the second embodiment of the present invention is the same as that described in the first embodiment, but not on the lead wires 4 and 5 but on the second layer electrode 3. The lead terminals 7 and 8 are soldered to each other, and the dielectric ceramic substrate 1, the first layer electrode 2 and the second layer electrode 3 are coated with an insulating resin or the like except for a part of the lead terminals 7 and 8. By forming the material 6, the surface mount type ceramic capacitor 200 can be obtained.
Although both the ceramic capacitors of the first and second embodiments are formed using a single substrate, it is needless to say that the present invention can also be applied to a laminated ceramic capacitor in which electrodes are stacked.

Next, as examples of the present invention, the dielectric ceramic composition of the present invention and a ceramic capacitor using the same will be described in detail. In addition, this invention is not limited at all by the following examples.
Table 1, Table 2 and Table 3 show the solid solution composition (in mol%, total 100 mol%) and BaCO ₃ and Bi ₂ O _{3 for} the examples and comparative examples of the present invention from sample No. 1 to No. 48. Excess amount added (in mol%), and dielectric properties and self-heating characteristics measured for each sample are shown.

First, using commercially available special grade reagents BaCO ₃ , TiO ₂ (rutile), Bi ₂ O ₃ , Mn ₂ O ₃ , Nb ₂ O ₅ , Ta ₂ O ₅ , SrCO ₃ , SnO ₂ and ZrO ₂ , the total amount of the solid solution composition is Each reagent blending weight was determined so as to be 0.1 mol, and weighed with an electronic balance. For example, in sample No. 2, BaCO ₃ 16.686 g, TiO ₂ 7.766 g, Bi ₂ O ₃ 2.174 g, Mn ₂ O ₃ 0.1579 g, Nb ₂ O ₅ 0.0665 g, SrCO ₃ 0.2953 g, SnO ₂ 0.1507 g, and ZrO _{2 is} 0.0370 g.

Next, these components were dry-mixed for 120 minutes using a raking machine (agate mortar and pestle). This mixed powder was pressure-molded at a pressure of 200 kg / cm ² using a 30 mmφ mold (piston cylinder type). These cylindrical compacts were heated on an alumina plate to 1060 ° C. at a heating rate of 200 ° C./h, held for 2 hours, and then cooled to room temperature at about 200 ° C./h.

  This calcined body was dry-pulverized for 90 minutes using a raking machine (agate mortar and pestle). Next, 7% aqueous solution of polyvinyl alcohol was added and mixed at 5% with respect to the weight of the powder, and granulated through a 50 mesh sieve.

This granulated product was pressure-molded into a disk shape with a pressing force of 700 kg / cm ² using a 10 mmφ mold. These same sample disk shaped bodies were stacked via 5-6 granulated powders, set on zirconia bed powder, and then fired using an electric furnace. The main firing conditions are: temperature increase / decrease rate of 200 ° C / h, temperature maintained at 700 ° C for 3 hours, temperature increased further, temperature maintained for 1200 hours (or 1220 ° C) for 2 hours did. The typical size of the dielectric ceramic obtained by the main firing is about 8.3 mm in diameter and about 1.0 mm in thickness.

  Next, after removing the granulated powder lightly adhering to the surface of the obtained dielectric porcelain, chamfering, measuring the shape dimension with a micrometer, and then applying an Ag electrode to the surface of the porcelain disc Then, baking was performed at 700 ° C. for 15 minutes. Then, lead wires were soldered to both surfaces of the Ag electrode. Furthermore, the ceramic capacitor which formed the exterior | packing material was obtained by coating an epoxy resin except the edge part of a lead wire.

Next, the capacitance (C), dielectric loss (tan δ), temperature characteristic (εr−TC), and self-heating characteristic (ΔT) of the obtained ceramic capacitor were measured.
Capacitance (C) and dielectric loss (tan δ) were measured using a YHP C meter 4278A under a signal voltage of 1 V / 1 KHz. The relative dielectric constant (εr) was calculated using the capacitance (C), the electrode area already measured using a micrometer, and the distance (thickness) between the electrodes. For temperature characteristics (εr-TC), the capacitance (C) at each temperature is measured with a YHP C meter 4278A, and the value at -25 ° C / + 85 ° C is displayed as a percentage based on the value at 20 ° C. I asked for it. The self-heating characteristic (ΔT) is applied to the porcelain capacitor by applying AC500Vp, frequency 100KHz, and a Φ0.1mm K-type thermocouple is in close contact with the outer surface of the porcelain capacitor. The temperature was measured, and the difference between the surface temperature and the ambient temperature at that time was defined as a self-heating characteristic (ΔT).

  These measurement results and the results obtained by calculation using these are shown in Tables 1, 2 and 3 together with the solid solution composition and the like.

  As is clear from the results of Tables 1, 2 and 3, the ceramic capacitor using the dielectric ceramic having the composition of the example of the present invention does not contain lead, and the temperature characteristics of the dielectric constant (εr-TC ) Shows excellent temperature smoothness of ± 15% or less (R characteristics), high dielectric constant (εr) as high as 1000 and self-heating (ΔT) as low as 40 ° C or less. We were able to.

(Example 1)
As can be seen from the results for dielectric ceramic capacitors having compositions from No. 2 to No. 10 in Table 1, all compositions with BiMnO ₃ content from 1.0 mol% to 2.0 mol% have a temperature characteristic of ± 15%. The following (R characteristics) smoothness is maintained, the relative dielectric constant is as high as 1000 or more, and the self-heating (ΔT) is as low as 40 ° C. or less. On the other hand, the No. 1 dielectric ceramic capacitor of Table 1 shown in Comparative Example 1 has a BiMnO ₃ content of less than 1.0 mol%, and therefore, the temperature characteristics of the relative permittivity have a change rate of ± 15% or more and R It does not meet the characteristics. On the other hand, the No. 11 dielectric ceramic capacitor of Comparative Example 2 has a BiMnO ₃ content exceeding 2.0 mol%, and therefore has a dielectric loss (tan δ) of 1% or more and a high self-heating (ΔT) of 47 ° C. The temperature exceeds 40 ° C and cannot be put to practical use.

In Example 1, the molar ratio between the BiMnO ₃ content and the Ba _1/2 NbO ₃ content is fixed at 2: 1. However, the molar ratio is not necessarily limited to this. However, the composition in the vicinity of this molar ratio satisfies the effect of smoothing the temperature characteristics and reducing the dielectric loss at the same time in a well-balanced manner. Furthermore, as can be seen from the results of Example 1, the porcelain composition having a BiMnO ₃ content of 1.4 mol% to 2.0 mol% exhibits excellent smoothing with a temperature characteristic of a change rate of ± 10% or less (B characteristic).

(Example 2)
No. 13 and No. 14 of Example 2 shown in Table 1 indicate the limit of the appropriate amount of Ba _1/2 NbO ₃ . That, Ba _1/2 NbO ₃ amount 0.3 mole% to 1.2 the value of e _r a mole percent range over 1000, tand is less than 1.0%, the self-heating ([Delta] T) is at 40 ° C. or less, the dielectric The rate temperature characteristic (e _r -TC) satisfies the change rate of ± 15% or less (R characteristic). The dielectric ceramic having a Ba _1/2 NbO ₃ content of 0.5 mol% to 1.0 mol% is as already described in Example 1.

On the other hand, in No. 12 of Comparative Example 3 in which the amount of Ba _1/2 NbO ₃ is less than 0.3 mol%, tand exceeds 1% and self-heating (ΔT) exceeds 40 ° C., which is not practical. Further, in No. 15 of Comparative Example 4 in which the amount of Ba _1/2 NbO ₃ exceeds 1.2 mol%, the relative dielectric constant εr is as small as less than 1000, which is outside the scope of the claims of the present invention.

(Example 3)
From the results of Example 3 shown in Table 1, it can be seen that the dielectric ceramic capacitor whose Bi _2/3 TiO ₃ content is in the range of 9.0 mol% to 15.0 mol% has a temperature characteristic of relative dielectric constant of ± 15% or less. (R characteristics), tand 1% or less, self-heating ([Delta] T) is the 40 ° C. or less and the dielectric constant e _r are satisfied over 1000 all properties at the same time. The Bi _2/3 TiO ₃ content in the range of 12.0 mol% to 15.0 mol% is as already described in Example 1.

On the other hand, No. 16 of Comparative Example 5 having a Bi _2/3 TiO ₃ content of less than 9.0 mol% has a temperature characteristic of −17% and does not satisfy the R characteristic. On the other hand, in the case of No. 21 of Comparative Example 6 in which the amount of Bi _2/3 TiO ₃ exceeds 15.0 mol%, the value of the relative dielectric constant εr is less than 1000, which is outside the scope of the present invention.

(Example 4)
In Example 4 shown in Table 2, the Ba _1/2 TaO ₃ component was used as a component having the effect of reducing the dielectric loss (tan δ) and reducing the self-heating (ΔT). From these results, it can be seen that dielectric ceramics with a Ba _1/2 TaO ₃ content ranging from 0.3 mol% (corresponding to No. 23) to 1.2 mol% (corresponding to No. 29) are Ba _1/2 NbO. as in the case of _three components, the ratio temperature characteristics of dielectric constant change rate ± 15% or less, tand 1% or less, self-heating ([Delta] T) is 40 ° C. or less, the value of the dielectric constant e _r is 1000 or more characteristics of the All meet at the same time. Further, even when the Ba _1/2 NbO ₃ component and the Ba _1/2 TaO ₃ component are used simultaneously as the solid solution composition, the capacitor characteristics can be almost the same as long as the total amount is the same as the simple substance amount.

Furthermore, even when using Ba _1/2 TaO ₃ component, as with Ba _1/2 NbO ₃ component, BiMnO ₃ content is less than 1.0 mol% (No. 22 in Comparative Example 7) and temperature characteristics of relative permittivity. Cannot be less than ± 15% (R characteristic). Further, when the amount of BiMnO ₃ is less than 1.0 mol% (No. 22 in Comparative Example 7), the rate of change in temperature characteristic ± 15% or less (R characteristic) cannot be obtained. On the other hand, if the amount of BiMnO ₃ exceeds 2.0 mol% (No. 30 in Comparative Example 8), tan δ exceeds 1% and self-heating exceeds 40 ° C., which is not practical.

(Example 5)
In Example 5 and Example 9 are shown in Table 3, depending on the molar% of BaCO ₃ ingredients excessively added with respect to the solid solution composition 100 mole% composed mainly of barium titanate, the dielectric ceramic capacitor It shows how the characteristics of the change. As can be seen from these results, the relative dielectric constant εr value slightly increases and the value of tanδ decreases as the amount of excessive addition of the BaCO ₃ component increases. However, when the excess amount exceeds 1.0 mol%, δr begins to decrease and tanδ begins to increase. When the excess amount exceeds 1.5 mol% (No. 36), the value of δr becomes less than 1000. Therefore, it is desirable that the excessive addition amount of the BaCO ₃ component does not exceed 1.5 mol%.

On the other hand, the relative permittivity temperature characteristic smoothes as the excess amount of the BaCO ₃ component increases. However, when the excess amount of BaCO ₃ is 1.5 mol% or more, the smoothing of temperature characteristics tends to be alienated.

(Example 6)
Example 6 and Example 10 shown in Table 3 show the relationship between the amount of Bi ₂ O ₃ component added excessively with respect to 100 mol% of the solid solution composition and the characteristics of the ceramic capacitor. Excessive addition of the Bi ₂ O ₃ component has a practically favorable effect of smoothing the temperature characteristics, reducing tan δ, and reducing self-heating, but also has an undesirable effect of reducing εr slightly. I have. In particular, when the Bi ₂ O ₃ excess exceeds 1.0 mol% (No. 41), the value of εr is less than 1000, so the Bi ₂ O ₃ excess is preferably within 1.0 mol%.

(Example 7)
Example 7, Example 11, and Comparative Example 12 shown in Table 3 show the relationship between the change in the main component amount of BaTiO _{3 in} the solid solution composition and the capacitor characteristics. From these results, it can be seen that when the amount of BaTiO ₃ exceeds 88.0 mol% (No. 42), the relative permittivity is high, but the change rate of the relative permittivity at −25 ° C. is ± 15% for the temperature characteristics. As a result, sufficient R characteristics are not satisfied. Accordingly, the BaTiO ₃ content is desirably 88.0 mol%. On the other hand, in the composition (No. 48) having a BaTiO ₃ content of less than 75.0 mol%, the value of εr is less than 1000 and at the same time the rate of change of the temperature characteristics exceeds ± 15%.

Here, the most preferable dielectric ceramic composition in the present invention will be described in detail. It is the following dielectric ceramic composition. That is, the BiMnO ₃ component is 1.4 mol% to 1.8 mol%, the Ba _1/2 NbO ₃ or Ba _1/2 TaO ₃ component is 0.6 mol% to 0.9 mol%, and the Bi _2/3 TiO ₃ component is 11.0 mol% to 13.0 mol%. mol%, SrTiO ₃ component 1.5 mol% to 2.5 mol%, BaSnO ₃ component 0.5 mol% to 1.5 mol%, BaZrO ₃ component 0.2 mol% to 0.5 mol%, and BaTiO ₃ components 84.8 mol% ～79.8 mol Dielectrics characterized in that 0.3 mol% to 1.0 mol% of BaCO ₃ components are excessively added to a solid solution composition containing 100 mol% of barium titanate as a main component. It is a body porcelain composition.

Examples corresponding to this composition are No. 4, No. 5, No. 6, No. 9 of Example 1, No. 25, No. 26 of Example 4, No. 32 of Example 5, No. 33, No. 34, No. 38 of Example 6. Dielectric ceramic capacitors made using these compositions have a high relative dielectric constant (εr) of 1900 or higher, a low dielectric loss (tanδ) of 0.40% or lower, and a low self-heating temperature of 30 ° C or lower. In addition, it is possible to provide a highly practical medium- and high-voltage ceramic capacitor that satisfies all of the excellent characteristics such as the smoothness of the temperature characteristics of the relative permittivity being a change rate of ± 10% or less (Β characteristics) and the like.
Here, the temperature characteristic of the relative dielectric constant is expressed by the rate of change based on the value at -25 ° C.

  As described above, according to the present invention, the temperature characteristic of the dielectric constant is smooth, the relative dielectric constant is high (over 1000), the self-heating is low, and all the characteristics are satisfied, but lead is not contained. It can be applied to various devices. The dielectric porcelain composition of the present invention is formed into a plate shape and electrodes are formed on the opposing surface to form a porcelain capacitor, which is a ballast circuit for a liquid crystal backlight inverter, a primary / secondary snubber circuit for a switching power supply, a television -Widely used as horizontal resonant circuits such as CRT displays, inverter fluorescent lamps, high voltage / pulse circuits for electronic devices, and surge circuits for communication modems. Needless to say, the dielectric ceramic according to the present invention can be used as a wiring board, a counter electrode is formed on the surface thereof, a portion thereof is a capacitor, a conductor, a resistor, etc. It can also be used as a substrate material for a wiring board such as forming an electronic circuit, and an additional capacitor having excellent temperature characteristics can be formed without requiring a large area.

The figure which shows the dielectric material ceramic capacitor of Embodiment 1 of this invention The figure which shows the dielectric material ceramic capacitor of Embodiment 2 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Ceramic capacitor 1 Dielectric ceramic substrate 2 1st layer electrode 3 2nd layer electrode 4, 5 Lead wire 6 Exterior material

Claims (6)

A solid solution mainly composed of barium titanate,
BiMnO ₃ component 1.0 mol% to 2.0 mol%, Ba _1/2 NbO ₃ or Ba _1/2 TaO ₃ component 0.3 mol% to 1.2 mol% and Bi _2/3 TiO ₃ component 9.0 mol% to 15.0 mol% Dielectric ceramic composition containing. The dielectric ceramic composition according to claim 1,
Solid solution composition as a main component barium titanate, 88.0 mol% ～75.0 mole% of BaTiO ₃ components, 1.0 mol% to 4.0 mol% of SrTiO ₃ components, 0.5 mol% to 3.0 mol% of BaSnO ₃ components and 0.1, A dielectric ceramic composition containing ₃ % by mole to ₃ % by mole of BaZrO ₃ component. The dielectric ceramic composition according to claim 1 or 2, wherein
A dielectric ceramic composition comprising 1.5 mol% or less of BaCO ₃ component added to a total amount of 100 mol% of a solid solution composition mainly composed of barium titanate. The dielectric ceramic composition according to claim 1 or 2, wherein
A dielectric ceramic composition comprising 1.0 mol% or less of a Bi ₂ O ₃ component added to a total amount of 100 mol% of a solid solution composition mainly composed of barium titanate. The dielectric ceramic composition according to claim 1 or 2, wherein
BiMnO ₃ component 1.4 mol% to 1.8 mol%, Ba _1/2 NbO ₃ or Ba _1/2 TaO ₃ component 0.6 mol% to 0.9 mol%, Bi _2/3 TiO ₃ component 11.0 mol% to 13.0 mol% SrTiO ₃ component 1.5 mol% to 2.5 mol%, BaSnO ₃ component 0.5 mol% to 1.5 mol%, BaZrO ₃ component 0.2 mol% to 0.5 mol%, and BaTiO ₃ component 84.8 mol% to 79.8 mol% A dielectric ceramic composition in which 0.3 mol% to 1.0 mol% of BaCO ₃ components are added to a solid solution composition composed mainly of 100 mol% of barium titanate composed of 7 components. The dielectric ceramic composition according to any one of claims 1 to 5 is used as a dielectric substrate,
A dielectric ceramic capacitor having the dielectric substrate sandwiched between first and second electrodes.

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