KR890002696B1 - High dielectric constant ceramic material and method of manufacturing the same - Google Patents

Abstract

Ceramic material having high-dielectric constant comprises a compsn. of formula (1-x)(Pb1-a-bBaaSrb) [(Zn1/3Nb2/3)1-c-d(Mg1/3 Nb2/3)cTid O3XBaTiO3 in which a is 0.035, b is 0-0.35, a+b is 0.01-0.35, c is 0-0.9, d is 0-0.5, c+d is 0-1.0 and x is 0.3-0.65. Said ceramic material is useful in high performance, low cast ceramic capacitors.

Description

High dielectric constant ceramic material and manufacturing method

FIG. 1 shows the temperature characteristics and dependencies of a capacitor as defined by X7R and Y5U in the American Institute of Electronics Engineers specification.

2 is a partially cut perspective view of a conventional capacitor made of a dielectric ceramic material.

Intrinsic properties of the present invention are a mixture of a first compound of a perovskite lead relaxant having a perovskite structure and a second compound based on a BaTiO ₃ powder having a particle size of at least 50 wt% of 0.7-3 μm. An auxiliary explanatory diagram showing the characteristics of the electrified ceramic material.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high dielectric constant ceramic material and a method of manufacturing the same, and more particularly, to a high dielectric constant ceramic material having a small temperature change according to dielectric constant over a wide temperature range and a method of manufacturing the same.

The characteristics required for the dielectric material include high dielectric constant, low dielectric constant versus temperature dependence, low dielectric loss (dissipation coefficient), small bias voltage dependence according to dielectric constant, and high capacitance resistivity. Particularly high capacitance resistivity (CR value) is required.

For example, the multilayer ceramic chip capacitor specification RC-3698B for electronic equipment of the EIAJ (Japan Electromechanical Industry Association) is specified to be 500 ㏁ · ㎌ or higher at room temperature.

In addition, the US Department of Defense MILC-55681 specifies high CR values at 125 ° C at high temperatures for use in more severe conditions.

In addition, stable temperature characteristics are required over a wide temperature range. For example, as shown in FIG. 1, the EIA standard has an X7R characteristic of ± 15% or less in the temperature range of -55 ° C to + 125 ° C. The amount of change is specified.

In the case of the stacked element, since the internal electrode layer and the dielectric layer are simultaneously fired integrally as shown in FIG. 2, it is necessary to use an electrode material that is stable even at the firing temperature of the dielectric material.

Therefore, if the firing temperature of the dielectric material is high, expensive materials such as platinum (Pt) and palladium (Pd) should be used. Therefore, it may be fired even at a low temperature of about 1100 ° C. or less so that a cheap material such as silver (Ag) can be used as the internal electrode material. To be able to do so.

Conventionally known high dielectric constant ceramic materials include barium titanate (BaTiO ₃ ) as a base and a solution of stannate, zirconium acid salt, titanate salt and the like.

However, the firing temperature of BaTiO ₃ -based material is high, about 1300-1400 ° C, and as an internal electrode material, an expensive material such as platinum, palladium, etc. must be used, which causes cost increase.

In order to solve such a problem of barium titanate, studies of various compositions are underway.

For example, ceramic dielectric compositions mainly composed of iron lead niobate (Japanese Patent Application Laid-Open No. 57-57204), magnesium lead niobate mainly (Japanese Patent Application Laid-Open No. 55-51759), and lead magnesium tungstate Mainly consisting of (special place 55-144609) and magnesium / iron / tungstate lead (special place 58-217462).

However, it was not possible to obtain a high dielectric constant ceramic material with a high dielectric constant, low temperature dependence, high insulation resistance, excellent electrical properties, and sintering at low temperature even in a wide temperature range of about -55 to ± 125 ° C.

On the other hand, it is also studied that the uniform temperature characteristics can be obtained by mixing compositions having different dielectric constant temperature characteristics.

For example, Japanese Patent Laid-Open No. 59-203759 discloses a material based on Pb (Mg _1/3 Nb _2/3 ) O ₃ -Pb (Mn _1/2 W _1/2 ) O ₃ and Pb (Mg ₁ A mixture of materials based on _{/ 3} Nb _2/3 ) O ₃ -PbTiO ₃ -Pb (Fe _2/3 W _1/3 ) O ₃ is described.

However, these mixtures have a high dielectric constant (T.C.C) and inadequate temperature characteristics.

Also, pages 427-429 of the Japanese Journal of Applied Physics vol.24 (1985) supplement 24-2 contain Pb (Fe _1/2 Nb _1/2 ) O ₃ and Pb (Fe _2/3 W _1/3 ) O. Mixtures of ₃ are described.

However, CR is not considered important as a capacitor material, and the T.C.C value is high and the temperature characteristic is inadequate.

SUMMARY OF THE INVENTION The present invention has been made with these problems in mind, and its main object is to provide a high dielectric constant ceramic material having high dielectric constant and insulation resistance, low temperature dependence, low temperature sintering, and suitable for high performance, low cost ceramic capacitors.

In order to achieve the stated object, the high dielectric constant ceramic material according to the present invention consists of a ceramic composition represented by the following formula.

(1-x) (Pb _1-ab Ba _a Sr _b )

_{{(Zn 1/3 Nb 2/3) 1} -cd (Mg 1/3 Nb 2/3) c Ti d} O 3. xBaTiO 3

a

0.350

a

0.35

b

0.350

b

0.35

a+b

0.350.01

a + b

0.35

c

0.90

c

0.9

0.50 <d

0.5

0 <c + d <1.0

x

0.650.3

x

0.65

In order to prepare the above-mentioned ceramic composition, the particle size of at least 50wt% of BaTiO ₃ powder used as raw material should be 0.7-3㎛.

In addition, a part of Ti in BaTiO ₃ may be substituted with Zr to be represented by the following formula.

(1-x) (Pb _1-ab Ba _a Sr _b )

_{{(Zn 1/3 Nb 2/3) 1} -cd (Mg 1/3 Nb 2/3) c Ti d} O 3. xBa (Ti 1-e Zr e) O 3

here

a

0.350

a

0.35

b

0.350

b

0.35

a+b

0.350.01

a + b

0.35

c

0.90

c

0.9

0.50 <d

0.5

0.060 <e

0.06

x

0.650.3

x

0.65

0 <c + d <1.0

Alternatively, a part of Ti in BaTiO ₃ may be replaced by Sn, and a part of Ba in BaTiO ₃ may be replaced by Sr · Ca or Ce.

Another object of the present invention is to provide a method for producing a high dielectric constant ceramic material made of the above-described composition.

)시키고, (c) 하소된 BaTiO₃를 적어도 50wt％의 BaTiO₃의 입자크기가 0.7-3㎛가 되게 분쇄하여 BaTiO₃를 베이스로 한 제1화합물을 얻고, (d) 소정의 혼합비율로 Pb·Ba·Sr·Zr·Nb·Mg 및 Ti산화물의 무게를 달고, (e) 무게를 단 산화물을 700-900℃에서 혼합하여 하소시키고, (f) 하소된 산화물을 입자크기가 0.7㎛보다 작은 분말로 분쇄하여 퀴리점이 125℃이하인 퍼로브스카이트(perovskite)구조의 퍼로브스카이트 납 완화제로 된 제2화합물을 얻고, (g) 소정의 비율로 제1 및 제2화합물의 무게를 달고, (h) 무게를 단 제1 및 제2화합물을 혼합하고, (i) 혼합된 화합물을 소정의 형태로 성형하고, (j) 성형된 조성물을 1000-1250℃의 저온에서 소결시킨다.In order to achieve the above object, a method of manufacturing a high dielectric constant ceramic material consists of the following steps. (a) Weigh BaCO ₃ and TiO ₂ at a rate such that BaTiO ₃ is formed, and (b) calcinate by mixing BaO ₃ and TiO ₂ with weight at 1000-1350 ° C.

(C) The calcined BaTiO ₃ is pulverized to have a particle size of at least 50 wt% of BaTiO ₃ of 0.7-3 μm to obtain a first compound based on BaTiO ₃ , and (d) Pb at a predetermined mixing ratio. Weighs Ba, Sr, Zr, Nb, Mg, and Ti oxides, (e) calcined by mixing the weighed oxide at 700-900 ° C., and (f) calcined oxide is less than 0.7 μm in particle size. Grinding to powder to obtain a second compound of a perovskite-lead perovskite structure having a Curie point of 125 ° C. or less, (g) weighing the first and second compounds in a predetermined ratio, (h) the weighed first and second compounds are mixed, (i) the mixed compound is molded into the desired form, and (j) the molded composition is sintered at a low temperature of 1000-1250 ° C.

The first compound represented by Ba (Ti _1-e Zr _e ) O ₃ in FIG. 3 provides high dielectric constant, high sintering temperature and large dielectric constant temperature dependence as shown in the right graph.

The second compound represented by (Pb _1-ab Ba _a Sr _b ) {(Zn _1/3 Nb _2/3 ) _1-cd (Mg _1/3 Nb _2/3 ) _c Ti _d } O ₃ is shown in the left graph. As shown, it provides high dielectric constant, high insulation resistance, low sintering temperature and large dielectric constant temperature dependence.

At this time, the particle size of the first compound should be 0.7-3㎛.

When these two compounds are mixed at the mixing ratio (x) as (first compound) _x (second compound) _1-x and sintered at the same time, high dielectric constant (K), high CR value, and low sintering temperature as shown in the center graph And a mixed sintered body having a uniform dielectric constant temperature dependency.

0.65로 하는 것이 좋고, 한편 낮은 소결온도가 요구되는 곳에서는 혼합물의 비를 0.3

x<0.5로 하는 것이 좋다.Also, where small temperature dependence is required, the ratio of the mixture is 0.5 <x

It is recommended to set the ratio to 0.65, while the ratio of the mixture is 0.3 when low sintering temperature is required.

x <0.5 is good.

The material of the present invention is described in more detail as follows.

In general, the following steps can be used to obtain high-k dielectric ceramics: oxides of (raw material) such as Pb, Ba, Sr, Zn, Mg, Nb, Ti, salts such as carbonates or oxalates that turn into oxides when burned, and oxides when burned The hydroxide or organic compound which is converted into is weighed by weight in a predetermined ratio, mixed well, calcined and ground to a raw powder.

The powder is molded into a desired shape and sintered to obtain high dielectric constant ceramics.

Instead of the general method described above, in the present invention, a raw material containing at least BaTiO ₃ powder and other compounds as raw powder is mixed before sintering.

As stated, the high dielectric constant ceramic compositions prepared can reduce the temperature dependence of the dielectric constant.

In more detail, the manufacturing method of the present invention consists of the following steps: as a starting material, an oxide of Ba and Ti constituting BaTiO ₃ , a salt, a hydroxide or an organic compound such as carbonate or oxalate which can be converted into an oxide by burning in a chemical chamber Prepare in advance to satisfy BaTiO ₃ and calcinate at 1000-1350 ° C.

The stoichiometry of the compounds may be somewhat different at this stage.

The calcined powder and the weight of the second starting materials are weighed in a predetermined ratio, mixed well and ground.

In this process, it is recommended to use a ball coated with a resin so that the BaTiO ₃ powder is not excessively crushed.

In addition, the second starting materials, mainly Pb (which may include BaTi), are mixed and calcined at 700-900 ° C. for separation.

It is also possible to include some other elements in the powder composed of BaTiO ₃ .

The powder is sufficiently mixed, molded into the desired shape and sintered into a high dielectric constant ceramic composition.

It is also advisable to use some stabilized zirconia balls of high hardness and strength to avoid contamination of the impurities in mixing and grinding the calcined powder and the second starting material.

In addition, it is preferable to use a perovskite structure of the second compound with a resin so as not BaTiO ₃ is excessively pulverized when mixed coating view of BaTiO ₃ to the one the subject a first compound, Pb as the main component.

The ceramic composition thus obtained is a mixed sintered body comprising a first compound having a main component BaTiO ₃ and a second compound having a perovskite structure whose main component is Pb.

The first compound of BaTiO ₃ has a Curie point of about 125 ° C., and a ceramic composition having excellent temperature characteristics or small temperature dependency can be obtained due to the multiplication effect according to the second compound containing Pb as a main component.

In addition, the ceramic composition of the present invention has a high dielectric constant and CR product, and thus is suitable for use in a capacitor.

If the BaTiO ₃ powder is excessively pulverized, the first and second compounds are excessively diffused during sintering, which is an obstacle to improving the temperature characteristics.

When too thick, the pore crack increases excessively in the sintered body, and when the multilayer capacitor is made, the CR area is lowered, the mechanical strength is lowered, and the production yield is lowered due to the heterogeneous composition.

Therefore, the particle size of BaTiO ₃ powder of 50 wt% or more is preferably 0.7-3 mu m, preferably 0.8-2 mu m.

The method of controlling the particle size is as follows: For example, when the particle size is large, the main chain condition of the ball is modified, and when the particle size is small, the calcination or precombustion condition is adjusted.

In addition, the Curie point of the second compound is set to 125 ° C or less in consideration of the temperature characteristic of BaTiO ₃ , and from room temperature to 80 ° C in consideration of the mutual reaction of the first and second compounds.

In addition, to lower the sintering temperature (below 1100 ° C.), it is preferable to use a second compound having a Curie point lower than room temperature.

In addition, in order to change the Curie point, the Ba part may be replaced by Sr · Ca or Ce or the Ti part may be replaced by Zr or Sn in the BaTiO ₃ powder.

The composition of the present invention will be described as follows.

The composition can be represented by the following general formula.

(1-x) (Pb _1-ab Ba _a Sr _b )

_{{(Zn 1/3 Nb 2/3) 1} -cd (Mg 1/3 Nb 2/3) c Ti d} O 3. xBaTiO 3

In the above formula, a small amount of Pb may be replaced with Ba or Sr to form a perovskite structure.

However, when a + b is less than 0.01, the perovskite structure is not easily formed, and thus the dielectric constant is low.

If c + d is outside the above-mentioned range, the temperature dependency of permittivity increases.

0.9가 바람직하다.And c + d in the range of (Zn _1/3 Nb _2/3 ) compounds

0.9 is preferred.

If x exceeds 0.65, the sintering temperature rises and below 0.3 increases the temperature dependence of the dielectric constant.

0.65가 바람직하고, 소결온도가 높으면 0.3

x

0.5가 바람직하다.0.5 <x especially if the temperature dependence is large

0.65 is preferred and 0.3 if the sintering temperature is high

x

0.5 is preferred.

If a, b, c, d, and x are fixed in the above-described ranges, for example, when the sintering temperature is as low as 1150 ° C., the ceramic composition has a high dielectric constant, a low dielectric constant temperature dependence and a high insulation resistance in a wide temperature range. You can get it.

Although the composition of the present invention mainly consists of

(1-x) (Pb _1-ab Ba _a Sr _b )

_{{(Zn 1/3 Nb 2/3) 1} -cd (Mg 1/3 Nb 2/3) c Ti d} O 3. xBaTiO 3

The stoichiometric components mentioned above may be somewhat different.

When the above-mentioned composition is converted into terms of oxide, it is as follows.

PbO 26.49 to 53.33 wt%

BaO 15.01 to 39.48 wt%

SrO 0.00-9.71 wt%

ZnO 0.49-6.86 wt%

MgO 0.00-3.14 wt%

Nb ₂ O ₅ 8.00 to 23.03 wt%

TiO ₂ 7.81-23.64 wt%

Preferably,

PbO 26.49 to 53.33 wt%

BaO 15.01 to 39.07 wt%

SrO 0.00-9.57 wt%

ZnO 0.49-6.86 wt%

MgO 0.00-3.14 wt%

Nb ₂ O ₅ 8.00 to 23.03 wt%

TiO ₂ 7.81-23.39 wt%

Among them, it is preferable to replace a part of Ti with Zr so that the dielectric constant decreases near the Curie point.

Therefore, Ba (Ti _1-e Zr _e ) can be used in place of BaTiO ₃ .

e

0.06)정도이다.However, in this case, the substitution amount of Zr is 6mo1% (0

e

0.06).

This is because if it exceeds 6mo1%, T.C.C increases at high temperature when the ceramics composed of the mixed sintered body are molded.

In addition, the above-mentioned composition is converted into an oxide as follows.

PbO 19.28-40.35 wt%

BaO 26.73-46.73 wt%

SrO 0.00-7.15 wt%

ZnO 0.36-5.11 wt%

MgO 0.00-2.33 wt%

Nb ₂ O ₅ 5.84-17.11 wt%

TiO ₂ 13.08 to 26.64 wt%

ZrO ₂ 0.00-1.93 wt%

You may contain an impurity, an additive, etc. within the range which does not impair the effect of this invention.

However, the amount of additives such as CaO, La ₂ O ₃ , MnO ₂ , CoO, NiO, Sb ₂ O ₃ , ZrO ₂ and SiO ₂ , such as transition elements and lanthanides, is at most 1 wt%.

In manufacturing a laminated structure, a binder, a solvent, and the like are mixed with the above-described raw powder or mixed and pulverized powder to obtain a slurry.

The slurry is molded into a green sheet, the internal electrode paste is printed on the green sheet, and predetermined sheets are laminated and pressed to sinter.

In the sintering process, since the dielectric material of the present invention can be sintered at low temperature, a low-cost material mainly composed of Ag can be used as the internal electrode material.

In addition, since the dielectric material can be sintered at low temperature, the present material can be effectively used as a film dielectric paste material for printing and baking on a printed circuit board.

Since the ceramic composition of the present invention has a high dielectric constant, a small temperature coefficient, and a large CR product even at a high temperature, reliability at a high temperature is good.

In addition, the bias voltage dependence on dielectric constant is good, as it is low at 10 ° C. or less at 2 kV / mm.

)이 매우 적으므로 고압용, 교류 회로용 및 고주파 회로용 유전 재료로서 사용할 수 있다.Therefore, the material of the present invention has a dielectric loss (dissipation factor (DF) or tan

) Is very small, and can be used as dielectric material for high voltage, alternating current circuit and high frequency circuit.

Since the temperature characteristic of the dielectric constant is excellent, when applied to the device of the electrical distortion, it is possible to obtain a device having a small temperature change relative to the displacement.

In addition, since the particle size can be uniformly arranged within 0.7-3 占 퐉, the breakdown voltage is high.

The mechanical strength of the material is also as good as the electrical properties described above.

EXAMPLE

An embodiment of the high dielectric constant material of the present invention will be described below.

In order to form BaTiO ₃ , starting materials BaCO ₃ and TiO ₂ were weighed by a balance, mixed in a ball mill, calcined at 1000-1350 ° C., and pulverized with a ball mill to form a chemical formula BaTiO ₃ .

In this case, the particle size of the obtained BaTiO ₃ powder was adjusted by changing the grinding conditions of the ball mill.

In addition, the average particle size was measured according to the Blaine method using the Blaine air permeation apparatus described in the test method of Japanese Industrial Standards R-5201-1964.

On the other hand, unlike BaTiO ₃ , oxides, hydroxides, or carbonates such as Pb.Sr.Zn.Ti.Mg were mixed in another ball mill and calcined at 700-900 ° C.

Subsequently, these calcined bodies were weighed in balance and mixed in a pot mill at a predetermined ratio.

After drying, the binder was mixed to form a granule, and the material was pressed to form a disc-shaped element having a diameter of 17 mm and a thickness of 2 mm.

The device was sintered in air at 1000-1250 ° C. for 2 hours (Examples 1-6 and Comparative Examples 1-2 were sintered at 1000-1100 ° C., while Examples 7-15 and Comparative Examples 3-5 were 1200- Sintered at 1250 ° C.).

Various characteristics were measured by baking Ag electrodes on both main surfaces.

Dielectric loss (dissipation factor) and capacity were measured with an LCR meter at 1 kHz · 1 Vrms and 25 ° C.

The permittivity was calculated based on these values. The insulation resistance was calculated based on the value measured with an insulation resistance meter after applying a voltage of 100 V for 2 minutes.

Moreover, the temperature characteristic (dependency) of dielectric constant was shown as the maximum rate of change in the temperature range of -55- + 125 degreeC with respect to 25 degreeC.

Capacity resistivity (CR) was obtained based on (relative permittivity) x (insulation resistance) x (dielectric constant in vacuum) at 25 and 125 ° C.

The insulation resistance in the silicone oil was measured to eliminate the wetting effect in the air.

Table 1 shows the test results of Examples 1-5 and 7-12 having the composition represented by the following formula.

(1-x) (Pb _1-ab Ba _a Sr _b )

_{{(Zn 1/3 Nb 2/3) 1} -cd (Mg 1/3 Nb 2/3) c Ti d} O 3 · xBaTiO 3 or

(Pb _{(1-x) (1-ab)} Ba _{(1-x) a + x} Sr _{(1-x) b} )

{(Zn _1/3 Nb _2/3 ) _{(1-x) (1-cd)} (Mg _1/3 Nb _2/3 ) _{(1-x) c} Ti _{(1-x) d + x} } O ₃

As a comparison, Comparative Example 1 (the particles are smaller BaTiO _3), special Example 6 (a BaTiO ₃ in order to lower the Curie point 10-30 ℃ than pure BaTiO ₃ (Ba _0.9 Sr _0.1) TiO ₃ in the place of the test (results Are shown in Table 1.

Table 1-a

TABLE 1-b

Table 1-c

In addition, the test results of Example 13-15 which is a composition represented by the following formula is shown in Table 2.

(1-x) (Pb _1-ab Ba _a Sr _b )

_{[(Zn 1/3 Nb 2/3) 1} -cd (Mg 1/3 Nb 2/3) c Ti d] O 3 · xBa (Ti 1-e Zr e) O 3

or

(Pb _{(1-x) (1-ab)} Ba _{(1-x) a + x} Sr _{(1-x) b} [(Zn _1/3 Nb _2/3 ) _{(1-x) (1-cd)} ( Mg _1/3 Nb _2/3 ) _{(1-x) c} Ti _{(1-x) d + x (1-e)} Zr _xe ] O _3.

The above-described composition includes Ba (Ti _1-e Zr _e ) O ₃ to lower the Curie point by 10-30 ° C. than the pure BaTiO ₃ together with Comparative Example 5.

Table 2-a

Table 2-b

Table 2-c

It can be seen from Table 1 that the ceramic composition of the present invention has a high dielectric constant (K = 4000 or more) and good temperature characteristics (+22 and -33% or less at -55 to + 125 ° C).

In addition, the CR area is larger than 5000 Pa · F (25 ° C.), and especially at 125 ° C., it is 1000 Pa · F or more, so that the reliability at the high end is excellent.

It can be seen from Table 1 that Comparative Example 1 having small BaTiO ₃ particles has a small dielectric constant and a wide temperature change rate.

In addition, in Comparative Example 2 having large BaTiO ₃ particles, the CR area is greatly reduced.

In addition, Example 6 having a Curie point of Ba _0.9 Sr _0.1 TiO ₃ having a Curie point of about 100 ° C. instead of BaTiO ₃ was able to obtain excellent characteristics.

In addition to the BaTiO ₃ substituted by Sr composition and the BaTiO ₃ substituted by Ca, Ce, Zr and Sn to lower the Curie point 10-30 ℃ also had also shown excellent properties.

In addition, it can be seen from Tables 1 and 2 that Examples 7-15 have a high dielectric constant (K = 2300 or more) and good temperature characteristics (within ± 10% at -55 to + 125 ° C).

Carried out using the _{Ba (Ti 0.95 Zr 0.05) O} 3 in place of BaTiO ₃ Examples 13 to 15 can achieve a superior temperature characteristic of less than ± 7.5% in a temperature range of -55- + 125 ℃.

Comparative Example 5 is a composition using Ba (Ti _0.88 Zr _0.12 ) O _{3 in} which a portion of Ti is substituted with 12 mol% of Zr instead of BaTiO ₃ . However, the rate of change of dielectric constant is over ± 10% at high temperatures. Therefore, the substitution rate of Zr should be within the scope of the present invention. Also hayeoseo replacing a part of the portion of the Sn Ti without substituting the Zr or Ba in BaTiO ₃ as a Sr, Ce, Ca was obtained the same result by using a lower Curie point 10-30 ℃ composition.

In addition, the multilayer ceramic capacitor molded using the composition obtained by adding 0.25 mol of Mon and CoO to Example 3 will be described as follows.

First, BaTiO ₃ and other calcined powder having the same composition as described above were weighed at a predetermined ratio, mixed with a slurry by adding an organic solvent and a binder, and painted with a thickness of 30 μm using a doctor blade caster. Molded into a sheet.

An electrode paste of 70 Ag / 30 Pd was printed on the green sheet in a predetermined pattern, and the sheets were stacked and stacked in 20 layers having the above-described electrode pattern.

Thereafter, the laminated sheet was cut into a predetermined shape, heated to completely burn the binder, and sintered at 1080 ° C. for 2 hours.

After sintering, an Ag paste was baked as an external electrode to prepare a multilayer ceramic capacitor. The electrical characteristics are shown in Table 3.

TABLE 3

The dielectric constant of the obtained multilayer ceramic capacitor was about 5700.

It can be seen from Table 3 that the properties are quite good. In particular, the temperature characteristic is less than ± 22 between -55 and + 125 ° C and satisfies the X7S characteristics in the EIA standard. Further, a multilayer ceramic capacitor molded using the composition obtained by adding 0.1 mol of MnO and CoO to Example 15 will be described below.

First, BaTi _0.95 Zr _0.05 O ₃ and calcined powder having the same composition as described above were weighed at a predetermined ratio, mixed with an organic solvent and a binder to form a slurry, and formed into a green sheet having a thickness of 30 μm as a doctor blade type casting machine. Molded. The 70PD / 30Ag electrode paste was printed on the green sheet in a predetermined pattern, and the sheets were stacked and stacked in 20 layers having electrode patterns.

The laminate sheet was then cut into the desired form and heated to allow the binder to burn out completely and sintered at 1220 ° C. for 2 hours.

After sintering, the Ag paste was baked with an external electrode to prepare a multilayer ceramic capacitor. The electrical characteristics are shown in Table 4.

TABLE 4

The dielectric constant of the obtained multilayer ceramic capacitor was about 2700. From Table 4 it can be seen that the characteristics are quite excellent.

In particular, the temperature specification is below ± 7.5 between -55 and + 125 ° C and satisfies the X7S characteristics in the EIA standard.

As described above, the method of manufacturing the high dielectric constant ceramic material of the present invention can provide a high dielectric constant ceramic composition having various excellent properties having high dielectric constant, small dielectric constant change rate over a wide temperature range, and particularly effective for multilayer ceramic capacitors.

In addition, in the production method of the present invention, lead zinc niobate and barium titanic acid were used as main components, but effects similar to those used in the present invention may be obtained by using other components.

According to the ceramic composition and the method of the present invention, a high dielectric constant ceramic material having high insulation resistance and excellent temperature characteristics can be obtained.

In particular, since a ceramic having improved temperature characteristics in a wide temperature range can be obtained, the ceramic material of the present invention can be excellently applied to a multilayer ceramic element such as a multilayer ceramic capacitor, a multilayer ceramic displacement element, and the like.

Claims (13)

A high dielectric constant ceramic material, comprising a composition represented by the following formula. (1-x) (Pb _1-ab Ba _a Sr _b ) [(Zn _1/3 Nb _2/3 ) _1-cd (Mg _1/3 Nb _2/3 ) _c Ti _d ] O ₃ .xBaO ₃ here 0

a

0.35 0

b

0.35 0.01

a + b

0.35 0

c

0.9 0 <d

0.5 0 <c + d <1.0 0.3

x

0.65 The high dielectric constant ceramic material of claim 1, wherein the particle size of at least 50 wt% of BaTiO ₃ is 0.7-3 μm. The method of claim 1, wherein the 0.3 to lower the sintering temperature

x

0.5 and 0 <c

High dielectric constant ceramic, characterized in that 0.9. 2. The method of claim 1, in order to make the temperature dependence on the permittivity small.

x

High dielectric constant ceramic material, characterized in that 0.65. The high dielectric constant ceramic material according to claim 1, wherein a part of Ti in BaTiO ₃ is substituted with Zr and is represented by the following formula. (1-x) (Pb _1-ab Ba _a Sr _b ) [(Zn _1/3 Nb _2/3 ) _1-cd (Mg _1/3 Nb _2/3 ) _c Ti _d ] O ₃ .xBa (Ti _1-e Zr _e) O ₃ here 0

a

0.35 0

b

0.35 0.01

a + b

0.35 0

c

0.9 0 <d

0.5 0 <e

0.06 0.3

x

0.65 0 <c + d <1.0 6. A method as claimed in claim 5, in order to achieve a sintering temperature of 0.3

x

0.5 and 0 <c

0.9 is a high dielectric constant ceramic material. 6. The method of claim 5, in order to make the temperature dependence on the permittivity small.

x

High dielectric constant ceramic material, characterized in that 0.65. The high dielectric constant ceramic material according to claim 1, wherein a part of Ti of BaTiO ₃ is substituted with Sn. The high dielectric constant ceramic material according to claim 1, wherein a part of Ba of BaTiO ₃ is substituted with Sr. The high dielectric constant ceramic material according to claim 1, wherein a part of Ba of BaTiO ₃ is substituted with Ca. The high dielectric constant ceramic material according to claim 1, wherein a part of Ba of BaTiO ₃ is substituted with Ce. (a) Weigh BaCO ₃ and TiO ₂ at a rate capable of forming BaTiO ₃ , (b) Calcin by mixing BaCO ₃ and TiO ₂ , weighed at 1000-1350 ° C., and (c) at least 50 wt% the size of the BaTiO ₃ particles are ground to a BaTiO ₃ calcined be a 0.7-3㎛ obtain a first compound to a BaTiO ₃ as a base, (d) a predetermined Pb · Ba · Sr · Zn · NB · Mg and Ti oxidation rate Weighed to the mixing ratio of (e) and calcined by mixing the weighed oxide at 700-900 ℃, (f) pulverized the calcined oxide into a powder having a particle size less than 0.7 ㎛ to fur 1250 ℃ Obtaining a second compound of a perovskite lead mitigator having a lobesky structure, (g) weighing the first and second compounds in a predetermined proportion, and (h) mixing the weighed first and second compounds (I) molding the mixed compound into a predetermined shape, and (j) sintering the molded composition at a low temperature of 1000-1250 ° C. Method for producing a high dielectric constant ceramic material, characterized in that. The method of claim 12 wherein (a) a binder and a solvent are added to the mixed composition to form a slurry, (b) cast to form a green sheet, and (c) 70 Ag / 30 Pd to 70 Pd on the molded green sheet. Printing electrode paste of / 30Ag, (d) stacking and laminating the green sheets before sintering, and (e) baking Ag paste or Ag / Pd paste as an external electrode on the sintered body to form a ceramic capacitor. A method of manufacturing a high dielectric constant ceramic material.

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