WO1992013810A1

WO1992013810A1 - Dielectric ceramic composition

Info

Publication number: WO1992013810A1
Application number: PCT/JP1992/000085
Authority: WO
Inventors: Shinji Abe; Tetsuo Yoshimoto
Original assignee: Nippon Soda Co., Ltd.
Priority date: 1991-01-31
Filing date: 1992-01-29
Publication date: 1992-08-20

Abstract

A dielectric ceramic composition of solid solution comprises lead manganotungstate [Pb(Mg1/2W1/2)O3], lead nickeloniobate [Pb(Ni1/3Nb2/3)O3], lead manganoniobate [Pb(Mg1/3Nb2/3)O3], lead titanate [PbTiO3], and lead zirconate [PbZrO3]. This composite material is expressed by the formula [Pb(Mg1/2W1/2)O3]X - [Pb(Ni1/3Nb2/3)O3]Y - [Pb (Mg1/3Nb2/3)O3]Z - [PbTiO3]U - [PbZrO3]W, where X + Y + Z + U + W = 1, and 0.05 « X « 0.3, 0.05 « Y « 0.5, 0.05 « Z « 0.75, 0.05 « U « 0.35, and 0.05 « W « 0.3. This dielectric ceramic composite material has excellent characteristics as a dielectric material for a monolithic ceramic capacitor.

Description

Specification

[Title of the Invention] Dielectric ceramic composition

【Technical field】

INDUSTRIAL APPLICABILITY The present invention provides a dielectric porcelain composition, in particular, which can be sintered at a low temperature of around 1000 ° G, has a high dielectric constant, a small temperature change rate of the dielectric constant, a high insulation resistance at room and high temperatures, and a mechanical strength. TECHNICAL FIELD The present invention relates to a dielectric ceramic composition for a ceramic capacitor having a high sintering temperature, a low dependence of electrical characteristics on a sintering temperature, and a small sintered body particle size.

[Background Art]

Conventionally, a dielectric ceramic composition for a ceramic capacitor, but porcelain composed mainly of titanate Barium (BaT i 0 ₃₎ has been widely put into practical use, as a main component barium titanate, usually 1 The sintering temperature is as high as 1300-1400 ° C. When this is used for multilayer ceramic capacitors, materials that can withstand this sintering temperature, such as platinum and palladium, are used as internal electrodes. They had to be used and had the disadvantage of high manufacturing costs. In order to make multilayer ceramic capacitors cheap, it is necessary to use porcelain that can be sintered at the lowest possible temperature, especially at 1000 ° C or lower, so that inexpensive metals, mainly silver and nickel, can be used for internal electrodes. . The electrical properties of the dielectric ceramic composition are basically required to have a high dielectric constant, a small dielectric loss, and a high insulation resistance.

In the case of a multilayer ceramic chip capacitor, when the chip capacitor is mounted on a substrate, mechanical distortion is applied to the chip capacitor due to the difference in the coefficient of thermal expansion between the substrate and the porcelain that constitutes the chip capacitor. The condenser may crack or break. In this case, the lower the mechanical strength of the porcelain forming the capacitor, the easier it is for cracks to occur, the more easily it is broken and the lower the reliability, and it is extremely important in practical use to increase the mechanical strength of the porcelain as much as possible. That is what. In the case of a composite multilayer ceramic component having a structure in which a dielectric layer and an insulator layer are laminated, the sintering temperature of the insulator is 850 to 1,000 ° C. 1 1

Two

Use of inexpensive metals mainly composed of silver, nickel, etc. as conductors for cost reduction, generation of stress due to compounding during sintering, and matching with insulator shrinkage characteristics, etc. Therefore, dielectric ceramics that can be sintered at 1000 ° C or less and have high mechanical strength are required.

In recent years, multilayer ceramic capacitors have been required to have a small capacity change rate with respect to the operating temperature and to be small and large in order to use electronic components at high temperatures and stabilize circuit characteristics. Regarding the rate of change in capacitance, for example, there have been known some that satisfy the Y5U characteristic and Y5T characteristic of the EIA standard in a temperature range of -30 to 85, but all have a dielectric constant of It is as low as 8000-12000 for Y5U characteristics and 6000-8000 for Y5T characteristics. Therefore, in order to reduce the size and capacitance of the ferroelectric capacitor and improve its temperature characteristics, it is necessary to find a dielectric ceramic composition with a high dielectric constant and a small rate of change in capacitance with respect to the measurement temperature. It is necessary to increase the capacitance by reducing the film thickness as much as possible and increasing the number of layers. However, in the conventional barium titanate-based porcelain, if the dielectric constant is to be increased, the grain size of the sintered body will be large, and if the multilayer capacitor having a thin dielectric layer is to be manufactured, the breakdown voltage will decrease. There was a drawback that the reliability also deteriorated.

_{Pb (g, / 2 W,} / 2) 03-Pb for _{_{(g l / 3Nb 2/3}} ) 03 -PfaTi0 3 system, are disclosed in such as JP 55- 1 No. 16662, magnesium tungstate It is known that a dielectric porcelain composition containing a large amount of lead has excellent characteristics in which the temperature change of the child is small. However, on the other hand, it is also known that there is a problem that the electrical characteristics are highly dependent on the sintering temperature and it is difficult to obtain a sintered body having stable electrical characteristics. In addition, since the sintered ceramics had a large particle size and low mechanical strength, it was difficult to manufacture a multilayer chip capacitor having a thinner film thickness. In order to improve this, various methods of synthesizing the powder of the raw material powder have been studied, but all have the disadvantage of increasing the production cost.

DISCLOSURE OF THE INVENTION

The present invention solves the above-mentioned problems, and at a low temperature range of 1000 ° G or less. Sinterable, high dielectric constant, low rate of temperature change of dielectric constant, low dielectric loss, high insulation resistance at room temperature and high temperature, high dielectric breakdown voltage, high mechanical strength, sintering temperature of electrical characteristics It is an object of the present invention to provide a dielectric ceramic composition having a low dependency and a small sintered body particle diameter.

① Configuration of the invention

The present invention, magnesium lead tungstate _{[Pb (Mg, / 2 W} , / 2) 0 3], nickel • niobate _{[Pb (Ni, / 3 Nb} 2/3) 0 3], magnesium niobate lead _{[Pb (Mg, / 3 Nb} 2/3) 0 3], lead titanate [PbTi0 _3], and consists of lead zirconate [PbZr0 _3] a solid solution ceramic composition,

_{CPb (Mg, / Z W,} / 2) 03] X - [Pb (Ni, / 3Nb 2/3) 0 3] y - [Pb (Mg 1/3 Nb 2/3) 0 3] z -

[PbTi0 ₃ ] u-CPbZr0 ₃ 3 w

Where X + Y + Z + U + W = 1

X, Y, Z, U, W

0.05≤Χ ≤0.3

0.05≤Υ ≤0.5

0.05≤Ζ ≤0

0.05≤U ≤0.35

0.05≤W ≤0.3

And a dielectric ceramic composition containing 4 mol% or less of manganese or a composite oxide containing manganese with respect to this composition.

② Detailed explanation

A. Raw material and manufacturing method for dielectric porcelain

The dielectric porcelain composition of the present invention uses, as a starting material, a starting compound such as an oxide, a hydroxide, or a carbonate, which becomes an oxide at a temperature of 600 ° C. or higher.For example, a weighed starting compound is subjected to ball milling or the like. After wet mixing, calcining is performed to obtain a raw material powder for the porcelain composition. The obtained raw material powder is molded, and then sintered at about 1000 ° C in the air. It can be manufactured.

As raw materials, instead of using individual oxides and carbonates, magnesium, nickel, tungsten, niobium, and other compounds are mixed and calcined to obtain magnesium niobate, nickel niobate, magnesium tungstate, etc. Complex oxides, mixtures thereof, and solid solutions of these complex oxides can also be used as starting materials. When these composite oxides or their solid solutions are used as starting materials, the calcining step is required twice or more, which increases the raw material cost, but increases the dielectric constant depending on the composition. It is advantageous as a material for high-performance ceramic capacitors.

□. Ratio of main component

In a composition containing more magnesium and lead tungstate than in the range of the present invention, the dielectric constant is small, the electrical characteristics are highly dependent on the sintering temperature, and the particle size of the sintered porcelain composition is large. It is not practical because it has disadvantages such as reduced strength. On the other hand, a composition having a content of less than 0.05 has a drawback that the temperature change of the dielectric constant is large and the temperature characteristic of the dielectric constant is unsuitable as a material for a ceramic capacitor having a flat temperature characteristic.

In the porcelain composition of the present invention containing five components including lead zirconate as a main component, it is possible to suppress the temperature change of the dielectric constant, to reduce the sintering temperature dependence of the electrical characteristics, and to suppress the grain growth. It becomes possible to sinter. However, a composition containing more lead zirconate than the range of the present invention is not practical because the dielectric constant is small and the induced loss at room temperature is large. On the other hand, a composition having a small content of 0.05 has a drawback that the temperature change of the dielectric constant is large, grain growth cannot be suppressed, and the transverse rupture strength is low.

Nickel 'lead niobate, magnesium' lead niobate, and a composition with a low lead titanate content of 0.05 are not practical because the dielectric constant is small. On the other hand, a composition in which the content of these components is larger than the range of the present invention has a disadvantage that the change in the dielectric constant with the measurement temperature is large. In particular, in a composition with a low lead titanate content of 0.05 mm, the temperature characteristics of the dielectric constant are suitable for practical ceramic capacitor materials. In order to achieve this, the content of lead zirconate must be increased, and the dielectric constant is greatly reduced, which is not preferable.

C. Additives

In addition, when a composite oxide containing manganese is added as an additive, although the capacitance is reduced, the temperature characteristic of the capacitance change is greatly improved as shown in the examples. The same effect can be obtained by increasing the percentage of magnesium, lead gungstenate, and lead zirconate contained in the main component, but their contents are limited for the reasons mentioned above. Therefore, a desired temperature characteristic of the dielectric constant can be obtained by appropriately adding a composite oxide containing manganese.

As the composite oxide containing manganese _{_{Pb (Mn, / 3 Nb 2/3}} ) 0 3, Pb (Mn, / 2 Nb, / 2) 0 3, Pb (Mn, / 3 Ta 2 z 3) 0 3, _{Pb (Mn, / 2 W,} / 2) 0 3, Pb (Mn, / 3 Sb 2/3) 0 3 and the like, Izure same effect can be obtained. These manganese-containing composite oxides may be used singly or in combination of two or more. The amount of the manganese-containing composite oxide varies slightly depending on the type, but is preferably 4 mol or less with respect to the main component. If it is added in excess, the dielectric constant becomes too low, and the insulation resistance decreases, which is not preferable.

2. Optional components

_{nO, Si0 2, ZnO, NiO} , Cr 2 0 3, MgO, Nb 2 0 5, gold厲酸products such as PbO and the like, the content location is can be appropriately selected within a range not impairing the effects . BEST MODE FOR CARRYING OUT THE INVENTION

Example 1

Purity 99.9¾ more lead oxide as the starting material (PbO), magnesium oxide (MgO), oxidation tungsten (W0 _3), nickel oxide (ΝίΟ), niobium oxide (Nb ₂ 0 _5), titanium oxide (Ti0 _2), using zirconium oxide (Zr0 ₂₎ and manganese carbonate (MnC0 _3), were each weighed so that the blending ratio shown in Table 1. Next, the weighed raw materials are wet-mixed in a riacetone using a ball mill, and then calcined in a magnesia crucible at 00-800 ° C. Raw material powder. Using the obtained raw material powder, a disk with a diameter of 10 mm and a thickness of 3 It was placed in a sheer sagger and fired in the atmosphere at 1000 ° C for 1 hour. The silver electrode was baked on the upper and lower surfaces of the sintered disk with a 600, and a 50V DC voltage was applied for 1 minute at room temperature with a super insulation resistance meter to measure the insulation resistance and calculate the specific resistance. Next, the sample was placed in a thermostat and the capacitance and dielectric loss at 25 at a frequency of 1 kHz and a voltage of 1 Vrms were measured with a digital LCR meter to calculate the dielectric constant. The average value of the four samples was used as the representative value. Furthermore, the capacitance and the dielectric loss were measured in a temperature range of −55 to +125, and the capacitance change rate based on the capacitance at 20 ° C. was calculated.

Table 1 shows the compounding ratio of each main component, the type and amount of additives, the dielectric constant and dielectric loss at 25 ° C, the specific resistance at room temperature, and the values at −30 and 85 with reference to 20 °. The values of Yongman change rate are shown. However, in Table 1, the main component, magnesium ■ Lead tungstate is denoted by P, nickel 'lead niobate is denoted by PNN, magnesium' lead niobate is denoted by PMN, lead titanate is denoted by PT, and lead zirconate is denoted by ΡΖ.比 ', Υ', Ζ '

,, >> 1 ('is expressed as a percentage «' + 丫 '+2' +1] '+» 1 (let's be -100).

Observation of the fracture surface of the sintered body with a scanning electron microscope revealed that the average grain size was as small as 2 #m and uniform.

Examples 2 to 11, 15 and 18

In the same manner as in Example 1, raw material powders of the ifi combination shown in Table 1 were prepared, and a sintered body was prepared at a sintering temperature of 1000, and the gas characteristics were measured. Table 1 summarizes the measured results. In addition, as a result of observing the fracture surface of the sintered body of Example 11 with a scanning electron microscope, the average particle size was 2 #m, which was a small and uniform microstructure.

Examples 12 to 14

Raw material powders having the composition shown in Table 1 were prepared in the same manner as in Example 1, and sintered bodies were prepared by changing the sintering temperature to 950, 1000, and 1050 ° G, and the electrical characteristics were measured. Even when the sintering temperature was changed at 100, almost no change was observed in the electrical characteristics. Table 1 summarizes the measured results.

Examples 16 and 17

Starting materials: 99.9 純度 or more pure lead oxide (PbO), magnesium oxide (MgO), acid Tungsten (W0 _3), niobium oxide (Nb ₂ 0 _5), titanium oxide (Ti0 _2), oxidized zirconium two ©厶(Zr0 _2), and using niobate nickel (NiNb ₂ 0 _6), Table 1 Each was weighed so as to have the indicated mixing ratio. After use niobium, nickel (NiNb ₂ 0 ₆₎ is wet-mixed a predetermined amount of niobium oxide and nickel oxide _{_{(ΝίΟ) (Nb 2 0 5}} ) as a starting material herein, those synthesized separately performing dry燥仮ware It is. Next, the weighed raw materials were wet-mixed in acetone using a ball mill to prepare raw material powders having the composition shown in Table 1 in the same manner as in Example 1 and sintered at sintering temperatures of 950 ° C and 1000. The body was created and the electrical properties were measured. Table 1 summarizes the measured results.

Example 19, 20

Purity 99.9¾ more lead oxide as the starting material (PbO), magnesium oxide (MgO), oxidation tungsten (W0 _3), niobium oxide (Nb ₂ 0 _5), titanium oxide (Τί0 _2), oxidized zirconium two ©厶( Zr0 _2), niobium, nickel (NiNb ₂ 0 _6), and using magnesium niobate (MgNb ₂ 0 _6), were each weighed so that the blending ratio shown in Table 1. Using the niobate nickel (NiNb ₂ 0 ₆₎ niobium oxide and nickel oxide _{_{(NiO) (Nb 2 0 5}} ) as a starting material herein, also magnesium niobate (MgNb ₂ 0 ₆₎ oxide and magnesium oxide (MgO) after wet mixing predetermined amounts niobium (Nb ₂ 0 ₅₎ as a raw material, dried to perform calcination is obtained by separately synthesized. Next, the weighed raw materials were wet-mixed in acetone using a ball mill to prepare raw material powders having the composition shown in Table 1 in the same manner as in Example 1 and sintered at sintering temperatures of 950 and 1000 ° C. The aggregate was formed and the electrical characteristics were measured. Table 1 summarizes the measured results.

Example 2 1 to 3 1

Raw material powders having the composition shown in Table 1 were prepared in the same manner as in Example I, and sintered bodies were prepared at sintering temperatures of 1000 ° C and 1050 ° C, and the electrical characteristics were measured. The results of the measurement are summarized in Table 1.

Comparative Examples 1 and 2

Powders having the main component mixing ratios shown in Table 2 were prepared in the same manner as in Example 1, and a sintered body of the porcelain composition was prepared at a sintering temperature of 1050, and the electrical characteristics were measured.The results shown in Table 2 were obtained. . Comparative examples 3 to 5

In the same manner as in Example 1, raw material powders having the mixing ratios of main components shown in Table 2 were prepared, and sintered bodies were prepared at sintering temperatures of 1000.1050 and 1100 ° C, and the electrical characteristics were measured. Table 2 summarizes the measured results. As shown in Table 2, when the sintering temperature changed by 100 ° G, the electrical characteristics changed significantly.

Comparative Examples 6 to 1 2

Raw material powders having the main component mixing ratios shown in Table 2 were prepared in the same manner as in Example 1, and sintered bodies were prepared at sintering temperatures of 1050 and 1100, and the electrical characteristics were measured. Table 2 summarizes the measured results. Further, as a result of observing the fracture surface of the sintered body of Comparative Example 4 with a scanning electron microscope, the average particle size was as large as 5 to 了 / zm, and the particle size distribution was not uniform.

Measurement of bending strength

From the sintered bodies of Examples 2, 9, 26 and 2 and Comparative Examples 4 and 7, 10 strip-shaped samples of 2 mm in thickness, 0.5 mm in thickness and 12 mm in length were cut out, and the bending strength was measured using a bending strength tester. Was measured. Table 3 summarizes the average values of the 10 samples measured.

Table 1. Examples

* 2: expressed Pb (Mn, / zW, / z) 0 3 Note 2) molS relative to the main component in!

¾ 2. Comparative examples

Table 3. Examples and Comparative Examples (Measurement of bending strength)

Note 1) * 1: Pb (Mn, _{/ 3} Nb 2/3) 0 ₃

Note 2) Expressed as mo for the principal component.

Note 3) The average value of the measured bending strength is shown.

92/13810 ^r

1 2

[Industrial applicability]

And As is clear from the results shown in Table _{1, Pb (Hg, / Z} W, / 2) 0 3 - Pb (Ni, / 3 Nb 2/3) 0 3 - Pb (g, / 3 b 2/3 ) 0 ₃ one PbTi0 ₃ one PbZr0 ₃ of a dielectric ceramic composition containing the composition, if Ku the present invention the additional inclusion added below 4 mol% of the composite oxide containing manganese, or a manganese as an additive to the composition In the range, the dielectric constant is high, the dielectric loss is as low as 0.7% or less, the specific resistance is as high as 4 xl (H2Qcm or more) at room temperature, the particle size of the sintered body is as small as 2 or less, and the mechanical strength is 1500 kg / cm ² or more, and by adding a manganese-containing composite oxide in a prescribed amount, the temperature characteristics can be adapted to the Y5U characteristics and Y5T characteristics of the EIA standard. A dielectric constant of 16000 is obtained with a dielectric constant of 6000 and a dielectric constant of 5 with characteristics of 5. Therefore, the porcelain composition of the present invention provides a small, large-sized ferromagnetic cell with a flat temperature characteristic of the dielectric constant. It can be said that it is extremely excellent as a material for lamic capacitors.

As can be seen from the electron micrographs of the fractured surface of the sintered body, the porcelain in the composition region according to the present invention has an extremely fine and uniform microstructure, so that the thickness of the ceramic layer is thinner. It can be said that it is suitable for manufacturing a capacitor. On the other hand, as shown in the comparative example, in the ceramics outside the composition range of the present invention, the grain size is large and the grain size distribution is not uniform. Therefore, when a ridged ceramic capacitor having a small thickness is manufactured, the dielectric breakdown voltage is reduced. Therefore, it was unsuitable as a practical material because its properties deteriorated.

Since the porcelain composition of the present invention has a low sintering temperature, the price of the internal electrode of the multilayer capacitor can be reduced by using an inexpensive metal, and the obtained porcelain can be made electrically. Since it has excellent characteristics and can cope with thinning of the dielectric layer, it is possible to manufacture a small and large-capacity multilayer ceramic capacitor.

Also, since it contains _three components of PbZr03, porcelain with excellent properties can be obtained without using a method of synthesizing the raw material powder, which would increase the production cost, and the particle size of the sintered body can be reduced. As shown in Table 3, the mechanical strength is greatly improved and the dielectric breakdown voltage is increased, so that a thinner and more reliable ceramic capacitor can be manufactured. In addition, as shown in Examples and Comparative Examples, The use of the composition in the formation region makes it possible to obtain a porcelain having stable electrical characteristics even when the sintering temperature changes, which is extremely excellent in practical use.

Claims

The scope of the claims

1. A magnesium 'lead tungstate _{[Pb (Mg, / 2/} 2) 0s], nickel' niobate _{_{[Pb (Ni 1/3 Nb 2/3)}} 0 3], magnesium ■ niobate _{[Pb (Mg, / 3 N} b 2/3) 0 3 3, lead titanate [PbTi0 _3], and lead zirconate [PbZrO ^3] Tona Ru solid solution ceramic composition

[Pb (Mg, 2Wi 2) 03] X-[Pb (Ni, 3 2/3) 03 j γ ~ Crb (gi / 3Nb2 / 3) 0 ₃ ] z-

[PbTi0 ₃ ] u-[PbZr0 ₃ ] _w

Where Χ + Υ + Ζ + ΙΗΪί = 1

X, Y, Z, U, W

0.05≤X ≤0.3

0.05≤Y ≤0.5

005≤Ζ ≤0.75

0.05≤U ≤0.35

0.05≤W ≤0.3

A dielectric porcelain composition comprising a composition represented by the formula:

2. A dielectric ceramic composition containing manganese or a manganese-containing composite oxide in an amount of 4 molX or less with respect to the composition according to claim 1.