JPH02242522A - Dielectric porcelain composition - Google Patents

Abstract

PURPOSE:To obtain a dielectric porcelain composition of high dielectric constant, high insulation resistance and high insulation breakdown voltage, being excellent in quality Q, and of small temperature coefficient of electrostatic capacity by making the composition contain a specific amount of vanadium oxide as auxiliary component against main components that the composition contains in such a manner that when an expression is given as xBaO-y[(TiO2)(1-m)(ZrO2)m]- zRe2O3, (x), (y) and (z) are in a specific mol ratio range. CONSTITUTION:The dielectric porcelain composition is made to contain vanadium oxide as auxiliary component by 0.005 to 1.00 parts by weight in V2O5 against 100 parts by weight of main components that the composition contains in such a manner that when an expression is given as xBaO-y[(TiO2)(1-m)(ZrO2)m]- zRe2O3 (x+y+z=1.00; 0.001<=m<=0.200; Re2O3 is at least one kind of rare earth element selected among La2O3, Pr2O11/3, Nd2O3, and Sm2O3), (x), (y) and (z) are in a mole ratio range surrounded by points (a) to (f) in the figure. The composition thereby has its dielectric constant, insulation resistance, insulation breakdown voltage enhanced, its quality Q made excellent, and its temperature coefficient of electrostatic capacity reduced.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention has high dielectric constant, insulation resistance, and dielectric breakdown voltage, excellent quality Q, and small capacitance temperature coefficient, and is suitable for use in multilayer ceramic capacitors. , prevents a decrease in capacitance and quality Q when the thickness of the internal electrode is reduced,
The present invention relates to a dielectric ceramic composition that can reduce variations in capacitance and quality Q.

Conventional technology Conventionally, the dielectric constant and insulation resistance are high, and the quality Q is excellent.
The following systems are known as dielectric ceramic compositions with a small capacitance temperature coefficient.

-Bad-TiO2-Nd2O3 system -Ba0-TiO2-Sm2O3 system Problems to be solved by the invention However, these compositions, for example, 0.11BaO-o,
A dielectric material consisting of a composition ratio of 6s TiO□-0,21Nd2O3 was used, and the internal electrode thickness of palladium was 4μ.
m, dielectric thickness 12 μm, internal electrode overlap dimension 1.2
・When a multilayer ceramic capacitor with a laminated structure of 19 dielectric layers is manufactured, the average value of capacitance is near 42 pF, the average value of quality Q is 8700, and the average temperature coefficient of capacitance is Value: N 35 p p m / ”C1
The average insulation resistance was 6.0×10 12 Ω, and the average dielectric breakdown strength was 117 kv/mπ, which were not satisfactory values for insulation resistance and dielectric breakdown strength. However, since the crystal grain size is as large as 1 to 5 μm, the porosity in the element increases, the electric field strength applied to each crystal grain becomes too strong, and the dielectric breakdown strength is not satisfactory.

Furthermore, in order to reduce the cost of multilayer ceramic capacitors and to prevent the occurrence of delamination, which is a structural defect inside the element body, the thickness of the palladium internal electrode was increased by 4.
When thinning from μm to 2 μm, a dielectric material with the above composition ratio is used, the dielectric thickness is the above, the internal electric reed overlap dimensions,
The average value of capacitance of a multilayer ceramic capacitor having a laminated structure with a number of dielectric layers becomes as small as 610 pF, and the variation in capacitance increases by 266 to 13 pF. Furthermore, there was a problem in that the average straightness of the quality level Q was as low as 4,000, and the variation in quality + tQ was large, ranging from 600 to 8,800.

Means for Solving the Problems 57 In order to solve these problems, the present invention
O-7[:'('rio2)(1-,n)(ZrO2)
, n': 1-zRe206, (where -X+y+Z=1.OO o, 001≦m≦0.200 Re203 is La2o, Pr2o, 1/3, Nd2o
5. oxide of at least one rare earth element selected from Sm2O3) Points a, b, c, and d, where x, y, and z represent the following.

For 100 parts by weight of the main component consisting of the molar ratio range surrounded by e and f, vanadium oxide V, 0 as a subcomponent.
5 to 3E Lteo,oo es ~1. A dielectric ceramic composition characterized by containing an amount of oooN is proposed.

Operation FIG. 1 is a ternary diagram showing the composition range of the main components of the composition according to the present invention.The reason for limiting the composition range of the main components will be explained with reference to FIG. In FIG. 1, sintering is extremely difficult in the A@ region. Furthermore, in region B, the quality Q decreases, making it impractical. Furthermore, in the case of C and D peaks, the capacitance temperature coefficient becomes too steep on the negative side, making it impractical. In region E, the temperature coefficient of capacitance shifts to a positive direction, but the dielectric constant is too small to be practical. Also, Re2O3 is La2o5, Pr2o1173
, Nd2O, , Sm2O3, fi, La
2o5, Pr20. ,．． 5, Nd2o5, Sm203 (
7) It is possible to shift the capacitance temperature coefficient in the positive direction without significantly lowering the dielectric constant, and La2
o5, Pr2011/3. Nd2o3, 1 of 5m2o5
The capacitance temperature coefficient can be adjusted depending on the species or combination.

Also, TiO2 is replaced with Zr02).

It has the effect of reducing the crystal grain size and increasing the dielectric breakdown strength without significantly changing the values of the dielectric constant, goodness Q, capacitance temperature coefficient, and insulation resistance, and the substitution rate m is 0. If it is less than .001, there is no substitution effect;
When these factors are combined, the dielectric constant, quality Q, and insulation resistance decrease.

Figure 2 is a graph showing the effect of containing the subcomponent v205 on the characteristics of a multilayer ceramic capacitor with respect to the main component of the composition according to the present invention.The reason for limiting the content range of v205 can be explained by referring to the graph. I will explain. As shown in Figure 2, v2o! By containing i, the insulation resistance and dielectric breakdown strength are improved, the capacitance and the quality Q are increased,
This has the effect of reducing variations in capacitance and quality Q. Insulation resistance and other-line breakdown strength are improved by containing v205, but the liquid containing v205 has a main component of 100%
Since the free capacity and quality Q of less than -0,005 parts by weight were low, and the variation in capacitance and quality Q was still large, it was excluded from the scope of this invention.

On the other hand, the content of v205 is 1. If OO0 parts by weight can be achieved, the quality Q and insulation resistance will decrease, and the temperature coefficient of capacitance will become large on the negative side, making it impractical.

The present invention'd further includes adding at least one kind selected from manganese, zinc, iron, and silicon fluoride to the above-mentioned base material to form Mn02=ZnOFe2O3 and S, respectively.
It can be added in an amount of 0.06 to 1.00 parts by weight per 100 parts by weight of the main component and subcomponent in terms of iO□. These additives are the dawn of porcelain @
It has the effect of improving the ridges, but if the amount added is less than 0.05 parts by weight, there is no effect.

On the other hand, if the amount is 1.00 parts by weight, the dielectric constant decreases, making it impractical.

Example The present invention will be explained below using specific examples.

(Example 1) Chemically high-purity BaCO3,'rio2 was used as the starting material.
, ZrOLaOPro, Nd2O3, Sm2032
-23-6 N and v205 were prepared so that the composition ratio was as shown in Table 1 below, and they were put into a rubber-lined ball mill equipped with a hollow ball with pure water, and after wet mixing, they were dehydrated and dried. . This dry grass powder was placed in a high alumina 9 p-1 crucible and calcined in air at 11 oo"c for 2 hours. This calcined powder was placed in a rubber-lined ball mill equipped with agate balls with pure fire. The pulverized powder was wet-pulverized and then dehydrated and dried. An organic binder was added to the pulverized powder to make it homogeneous. The pulverized powder was sized through a 32-mesh sieve, and then molded using a mold and a hydraulic press at a molding pressure of 1 tOn/CrI to a diameter of 15φπ. The molded disk was then molded to a thickness of 0.4 mm.The molded disk was then placed in an alumina pod containing zirconia powder, and dielectric porcelain having the composition ratio shown in Table 1 below was obtained in air.

The thickness and diameter of the dielectric porcelain disk obtained in this way were measured, and the samples for measuring the dielectric constant, good IQ, and static capacitance temperature coefficient were prepared by baking silver electrodes on both sides of the dielectric porcelain disk. For the samples for measuring insulation resistance and edge breaking strength, a part without a silver electrode was provided inside the outer periphery of a dielectric ceramic disk, and a silver electrode was baked onto it. The dielectric constant, goodness Q, and static capacitance temperature coefficient were measured using a YHP digital LCR meter model 4275A at a measurement temperature of 20° C1 measurement 10
,,-7 Voltage 1. OVrms was determined by measurement at the measurement frequency IMl-1z. In addition, capacitance temperature coefficient, 20'C
The capacitance at 185°C was measured and calculated using a linear equation.

TG=(C-Go)/CoX 1/65X106T
C: Temperature coefficient of capacitance (ppm/℃) Go: Capacitance at 20"C -1 廿 (pF) G: Capacitance C at BE5'Q
pF) The dielectric constant was calculated from the following formula.

K -143,8X Co This is YHP HR meter model #4.
329A is used, and the measurement voltage is 5 Q V, D, C.

It was determined by measurement with a measurement time of 1 minute.

The dielectric breakdown strength was determined by using a high-voltage power supply Pf manufactured by Kikusui Electronics Co., Ltd. (Type 13 in 535), placing the sample in silicone oil, and calculating the breakdown voltage by changing the voltage at a step-up rate of 50 V/sec. The dielectric breakdown strength was calculated by dividing the dielectric thickness by the dielectric thickness, and the dielectric breakdown strength was determined as 11/, -7 1 kg.The crystal grain size was determined by optical microscopic observation at a magnification of 1:400.

The test conditions are also shown in Table 1, and the test results are shown in Table 2 below.
Shown in the table.

(Left below) 13 to 14, - (Example 2) Starting materials include chemically highly purified BaCO3, TiO2,
zrO2,L? L203. Pr60. , -Nd
2O3, Sm2O3゜v2051Mno2, ZnO, F
e2O, and $102 powder were weighed to have the composition ratios shown in Table 3 below, and then treated in the same manner as in Example 1 to produce a conductive material with the composition ratios shown in Table 3. Got porcelain.

The testing methods for these samples were the same as in Example 1, the test conditions are also shown in Table 3, and the test results are shown in Table 4 below.

(Left below) 17 H/ (Example 3) Chemically high-purity BaCO3, TiO2゜ZrOLa OPr ONd O, Sm2032 Toshiba were used as raw materials.
Using 25-611-25 and v205 powder, main component 0.11 BaO-0
-68((T iOz ) o, 9 (ZrO2)
ol) against O-21Nd 205, v205 as OO,001,0,0050,010,0,10o,
A crushed Sakayaki powder containing 1.000.2.000 wtH is prepared in the same manner as in Example 1. However, v205
Content 0, 0.0012, 0OWt (X is outside the scope of this invention, 0.005.0.010.0.10
0.1.000 wt% is within the scope of this invention.

An organic binder, a plasticizer, a dispersant, and an organic solvent were added to this calcined and pulverized powder and mixed in a polyethylene pot equipped with alumina balls to prepare a slurry. After mixing, 3
It was filtered using a nylon cloth of 0.00 mS. The slurry after filtration was formed into a sheet using a doctor blade on a polyester film that had been subjected to mold release treatment so that the dielectric thickness after sintering was 12 μm.

8A-2 Next, 1 to 10 sheets peeled from the polyester film were laminated on a support stand. On top of this, ML3724 (Palladium base for the back facing electrode) of Shoei Kagaku was screen printed so that the internal electrode thickness after sintering was 2 μm.
Dry. A sheet peeled from a polyester film was laminated on top of this. On top of this, internal cup palladium paste was printed by shifting the printing position so that the internal electrode overlap dimensions after sintering were 1.2717ffx0.7ffffl, and after drying, one sheet peeled from the polyester film was laminated. . These operations are performed when the number of dielectric layers is 19.
Repeat the manipulation until it becomes . On top of this, 10 sheets peeled from a polyester film were laminated. After sintering this laminate, the internal electrode overlap dimension is 1.2 ffff XO,
No. 7777711 was cut into a multilayer ceramic capacitor having a multilayer structure with a dielectric thickness of 12 μm and 19 dielectric layers. The cut sample was placed in an alumina sheath containing zirconia powder, heated in air from room temperature to 360'C at a rate of 5°C/hr, and heated to 350°C.
Increase the temperature by 1oo'c/hrf.

19.

After firing at 1270°C for 2 hours, the temperature was lowered to room temperature at 1oo"C/hr. Next, the fired sample was placed in a polyethylene bottle with water-resistant sandpaper on the inside, along with pure water, and the polyethylene bottle was rotated for firing. The rear surface of the sample was polished to fully expose the internal mold and original part that would be connected to the external electrode.The sample was removed from the polyethylene pot and after drying, a silver external electrode was baked on the exposed part of the internal electrode.
A multilayer ceramic capacitor was fabricated by connecting it to the internal electrode.

The capacitance, quality Q, capacitance temperature coefficient, insulation resistance, and dielectric breakdown strength of these samples were determined by measurements under the same conditions as in Example 1. The confirmation of the laminated structure is still limited to approximately 1/2 of the length and width of the laminated ceramic capacitor.
The polished cross section was determined by optical robustness observation using the internal electrode type dimension U at a magnification of 100, and the dielectric thickness and internal electrode thickness at a magnification of 400.

The measurement results are shown in FIG.

In addition, in the method for manufacturing dielectric ceramic in the example, Ba
GO,, ZrO2, TiO2, La2O3, Pr60.
,, NdOSmOVOMnOZnO Fe2O3 and 5102 were used, but the method is not limited to this method. Compounds such as BaTi05, or addition of charcoal salt, hydroxide, etc. in the air are used to obtain the desired composition ratio. By B? LOZrOT10
LaO? rONd05m0, 'VO-
Even if compounds such as MnOZn◯, Fe2o3 and SiO□ are used as protection, properties comparable to those of the examples can be obtained.

However, even if the main component is calcined in advance and subcomponents are added, properties comparable to those of the examples can be obtained.

Effects of the Invention According to the present invention, the dielectric constant, insulation resistance, and dielectric breakdown voltage are high, the quality Q is excellent, the capacitance temperature coefficient is small, and when used in a multilayer ceramic capacitor, The thickness of the internal electrode is reduced to prevent a drop in capacitance and quality Q.

Reduce the variation in static volume meter and quality Q21
/Meanwhile, by reducing the thickness of the internal electrodes, it is possible to reduce the cost of the laminated ceramic capacitor and to prevent the occurrence of delamination, which is an internal structural defect. Also,
Since the dielectric breakdown voltage is high, it is possible to reduce the thickness of the dielectric layer, thereby making the element smaller and increasing the capacity.

Furthermore, the addition of manganese, zinc, iron and silicon oxides allows the firing temperature to be lowered.

[Brief explanation of drawings]

FIG. 1 is a ternary diagram explaining the composition range of the main components of the composition according to the present invention, and FIG. 2 is a ternary diagram illustrating the composition range of the main components according to the present invention.
1BaO-0,68((TiO2),,(ZrO2)o
, + ) -0,21 subcomponent v205 for Nd206
2 is a graph illustrating the effect of the inclusion of 12 μm on the electrical characteristics of a multilayer ceramic capacitor having a laminated structure with a dielectric thickness of 12 μm, an internal electrode overlap dimension: 1.2×0.7ffiπ, and a number of dielectric layers=19.

Claims (2)

[Claims] (1) General formula xBaO-y [(TiO_2)_(_1_-_m_)(
When expressed as ZrO_2)_m]-zRe_2O_3, (where x+y+z=1.00 0.001≦m≦0.200 Re_2O_3 is La_2O_3, Pr_2O_1_
1_/_3, Nd_2O_3, Sm_2O_3) x, y, z are from the molar ratio range surrounded by each point a, b, c, d, e, f expressed below. A dielectric ceramic composition containing 0.005 to 1.000 parts by weight of vanadium oxide as a subcomponent in terms of V_2O_5 based on 100 parts by weight of the main component. ▲Contains mathematical formulas, chemical formulas, tables, etc.▼ (2) For 100 parts by weight of the main component and subcomponents combined, at least one selected from manganese, zinc, iron, and silicon oxides is added to MnO_2 and ZnO, respectively.
, 0.05 in terms of Fe_2O_3 and SiO_2
1. The dielectric ceramic composition according to claim 1, wherein 1.00 parts by weight is added.