JPH02242520A - dielectric porcelain composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is applicable to multilayer ceramic capacitors which have high dielectric constant, insulation resistance, and dielectric breakdown voltage, greatly improve good dust Q, and have a small capacitance temperature coefficient. The present invention relates to a dielectric ceramic composition that can prevent a decrease in capacitance and good dust Q when the thickness of the internal electrode is made thin, and can reduce variations in capacitance and good dust 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 small capacitance temperature coefficients.

・BaOTiO2Nd2O3 system -BaO-TiO2-Sm2O3 system Problems to be solved by the invention However, these compositions, for example, 0,09BaO-0,
A dielectric material composed of 56Ti02-0, 35NdO3/2 is used, and the palladium internal electrode has a thickness of 4 μm.
, dielectric thickness 12 l1m, internal electrode overlap dimension 1
．． When a multilayer ceramic capacitor with a laminated structure of 2 mm x 0.7 mm and 19 dielectric layers is manufactured, the average value of capacitance: 742 pF, and the average value of quality Q: 870.
0, average value of capacitance temperature coefficient: NN35pp/'C5
The average value of insulation resistance: 6.0×10 Ω, and the average value of dielectric breakdown strength: 11 akv/mm, which are not satisfactory values for insulation resistance and dielectric breakdown strength.

In addition, 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 to 41 mm.
tm to 271 m (thinner), the capacitance of a multilayer ceramic capacitor using a dielectric material with a composition ratio of 1 above, and having a multilayer structure with the above dielectric thickness, internal electrode type and dimensions, and number of dielectric layers. As the average value decreases to 610 pF, the variation in capacitance increases to 256 to 713 pF.Furthermore, the average value of the quality Q decreases to 4000, and the variation in the quality Q increases to 600 to 8800. was there.

Means for Solving the Problems In order to solve these problems, the present invention provides the general formula xB?
LO-yTi02-z(Re(+-c)Mec)0
When expressed as 372 (X+7-4-Z=1-00
,0.01≦C≦0,2Raid, La, Pr,
At least one rare earth element selected from Nd and Sm. Me is La, Pr, Nd.

At least one rare earth element selected from rare earth elements excluding Sm. ), X, y, z are each point a, b represented below
, c, d, e, f 5 to 2-000 parts by weight of vanadium oxide in terms of v205 was contained as a subcomponent to 100 parts by weight of the main component consisting of the molar ratio range surrounded by , c, d, e, f. This paper proposes a dielectric ceramic composition characterized by the following.

FIG. 1 is a ternary diagram showing the composition range of the main components of the composition according to the present invention, and the reason for limiting the composition range of the main components will be explained with reference to FIG. That is, sintering is extremely difficult in the region. Furthermore, in region B, the quality Q decreases, making it impractical. Furthermore, in the G and D regions, the capacitance temperature coefficient becomes too large 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, R
By selecting e from La, Pr, Nd, Sm, etc., it is possible to shift the capacitance temperature coefficient in the positive direction without significantly lowering the dielectric constant in the order of La, Pr, Nd, and Sm. La,
The temperature coefficient of capacitance can be adjusted by using one type or a combination of Pr and NdSm.

Furthermore, as is clear from Tables 1 and 2, which will be described later, L
A part of at least one rare earth element selected from a, Pr, Nd, Sm, La, Pr
, Nd.

Substitution with at least one rare earth element selected from rare earth elements excluding Smf has the effect of significantly improving the goodness Q, and if the substitution amount C is less than 0.01, there is no substitution effect. If it exceeds 0.20, the dielectric constant decreases and becomes impractical.

FIG. 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, and the reason for limiting the content range of v205 will be explained with reference to the graph. .

As shown in Figure 2, the inclusion of v2o5 improves insulation resistance and dielectric breakdown strength, increases capacitance and quality Q, and has the effect of reducing variations in capacitance and quality Q. have Insulation resistance and dielectric breakdown strength are improved by containing v205, but if the content of v205 is less than 0.005 parts by weight per 10 parts by weight of the main component, the capacitance and goodness Q will be low. In addition, since the capacitance and quality Q varied widely, it was excluded from the scope of the present invention. On the other hand, if the content of v2o5 exceeds 1.000 parts by weight based on the main component, the quality Q and insulation resistance will decrease, making it impractical.

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

(Example 1) Chemically high purity BaCO3, TlO2+ are used as starting materials.
La2O5, pr6o1j, Nd204, Sm
2O3, GeO2.

Gd2O3, Dy2O3 and v205 powder wood were weighed to have the composition ratio shown in Table 1 below, put into a rubber-lined ball mill equipped with agate balls together with pure water, wet mixed, and then dehydrated and dried. This dry powder was placed in a high alumina crucible and calcined in air at 1100°C for 2 hours. This calcined powder was placed in a rubber-lined ball mill equipped with an agate ball together with pure water, wet-pulverized, and then dehydrated and dried. After adding an organic binder to the pulverized powder and making it homogeneous, the granules were sized through a 32-mesh sieve and molded to a diameter of 1 ton/ca using a mold and a hydraulic press at a molding pressure of 1 ton/ca.
It was molded to a size of 5 mm and a thickness of 0.4 mm. Next, the molded disk was placed in an alumina pod lined with zirconia powder.
Dielectric ceramics having the composition ratios shown in Table 1 below were obtained in air.

The thickness and diameter of the dielectric ceramic disk obtained in this way were measured, and the sample for measuring the dielectric constant, goodness Q, and capacitance temperature coefficient was made of silver on both sides of the dielectric ceramic disk. The sample for measuring insulation resistance and dielectric breakdown strength was prepared by baking a silver electrode on a dielectric ceramic disk having a width of 1111 m in a part without a silver electrode inside the outer periphery. The dielectric constant, quality Q, and capacitance temperature coefficient were determined using YHP Digital/1. /
Using an LCR meter model/l/4275A, the measurement temperature was 20C and the measurement voltage was 1. OVrms, measurement frequency 1M
It was determined by measurement at Hz. Note that the temperature change in capacitance is -55'C.

Measure the capacitance at -25℃, 20'C, 85℃, and 125℃ to confirm linearity, and calculate the capacitance temperature coefficient using the following formula using the capacitance at 20C and 85C. Ta.

TC-(C-CO)/CO×1/66×106TC: Capacitance temperature coefficient (ppm, /'c) GO: Capacitance at 20°C (pF) C: Capacitance at 85°C ( pF) Further, the dielectric constant was determined from the following formula.

K = 1438 HR meter model/l
'4329A, the measurement voltage was 5ov, D, a measurement time was 1 minute.

And the dielectric breakdown strength is Kikusui Electronics Co., Ltd. 107,
-7 Using Type 13 as the mold cavity voltage power supply PH335, put the sample in silicone oil, divide the dielectric breakdown voltage determined by the voltage increase rate of 50 V/sea by the dielectric thickness, and calculate the dielectric breakdown strength per 1 mm. And so.

Test conditions are also shown in Table 1, and test results are shown in Table 2 below.

(Left below) (Example 2) Starting materials include chemically highly purified BaCO3 and Ti02N.
Using d203, GeO2 and v205 powder, main component 0,09BaO-0,56Ti02-0,3E
5 ((Nd03/2)O95(GeO2)oo5), v205 is ○, 0.Ool, o, oO5, o010
+Q100.1000.2. ○Oo, 3.000wt
% of calcined pulverized powder is prepared in the same manner as in Example 1. However, v205 content ○, 0.001.3,0
00 wt% is outside the scope of this invention, and 0.006.
0-010.0jO0,1-000,2,000wt%
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 an alumina ball to prepare a slurry. After mixing, 3
It was filtered using a 00 mesonyu nylon cloth. The slurry after filtration was formed into a sheet using a doctor blade on a polyester plastic film which had been subjected to a mold release treatment so that the dielectric thickness after sintering was 12 μm. Next, place 10 sheets peeled from the polyester film on a support stand.
4,,-7 laminated. On top of this, Shoei Kagaku Co., Ltd. type internal electrode palladium paste ML-3724 was screen printed so that the internal electrode thickness after sintering would be 2 μm, and then dried. A sheet peeled from a polyester film was laminated on top of this. On top of this, the internal electrode overlap dimension after sintering is 1.2 m.
The internal electrode palladium paste was printed by shifting the printing position so that it was m x 0.7 mm, and after drying, one sheet peeled from the polyester film was laminated. These operations were repeated until the number of dielectric layers reached 19. 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 mm x O, 7 mm, dielectric thickness: 12 μm It was cut into a multilayer ceramic capacitor having a laminated structure with 19 dielectric layers. This cut sample was placed in an alumina sheath lined with zirconia powder, heated in air from room temperature to 350C at a rate of 6℃/hr, and heated for 3 hours.
Raise the temperature from 60C at 100℃/hr, and raise the temperature at 1270℃ for 2
After baking for an hour, the temperature was lowered to room temperature at a rate of 1 ooc/hr. Next, the fired sample was placed in a polyethylene pot with water-resistant sandpaper on the inside, along with pure water, and the polyethylene pot was rotated to polish the surface of the fired sample to fully expose the internal electrode portion that will be connected to the external electrode. Ta. This sample was taken out from the polyethylene pond and dried, and then a silver external electrode was baked onto the exposed part of the internal electrode to make it electrically conductive with the internal electrode, producing a multilayer ceramic capacitor.

The capacitance, quality Q, temperature coefficient of capacitance, insulation resistance, and dielectric breakdown strength of these samples were determined by measurements under the same conditions as in Example 1. In addition, the laminated structure can be confirmed by optical microscope observation of a polished cross section of approximately A in the length and width directions of a multilayer ceramic capacitor, with the internal electrode overlap dimension at a magnification of 100, and the dielectric thickness and internal electrode thickness at a magnification of 400. I asked for it.

The measurement results are shown in FIG.

In addition, in the method for manufacturing the dielectric layer 2g in the example, B
'1LC05, TiO2, La2O3, Pr601+
, Nd2O3゜Sm2O3, CeO2, Gd2O3,
Although Dy2O3 and v205 were used, it is not limited to this method, and B
By heating compounds such as aTiOx, carbonates, hydroxides, etc. in air, BaO, TiO2, LA20
g, Pr60H.

Nd2O3, Sm2O3, CeO2, Gd20B,
Even when compounds D7205 and v205 are used, properties comparable to those of the examples can be obtained.

Further, even if the main components are roughened and calcined and subcomponents are added, properties comparable to those of the examples can be obtained.

In the example, La, Pr, Nd, Sm
Cθ, D7, (
.

In addition to the basic composition mentioned above, 5i02, MnO
Salts, oxides, etc., which are generally considered to be fluxes, such as 2+Fe2O3 and ZnO, can also be added within a range that does not impair the properties.

Effects of the Invention As described above, according to the present invention, the dielectric constant, insulation resistance, and dielectric breakdown voltage are high, the quality Q is greatly improved, the capacitance temperature coefficient is small, and the capacitor can be used in multilayer ceramino 9 capacitors. In order to prevent a decrease in capacitance and quality Q when the thickness of the internal electrode is made thinner, and to reduce variations in capacitance and quality Q, the thickness of the internal electrode is made thinner.
The cost of multilayer ceramic capacitors can be reduced, and delamination, which is an internal structural defect, can be prevented from occurring. In addition, because the dielectric breakdown voltage is high, the thickness of the dielectric layer has been reduced and the product has been made smaller.

Larger capacity is possible.

[Brief Description of the Drawings] Figure 1 is a ternary diagram explaining the composition range of the main components of the composition according to the present invention, and Figure 2 is a ternary diagram illustrating the composition range of the main components of the composition according to the present invention.
BaOO,56TiO20,35C(Nd03/2)
o 9s (C602) o os ] subcomponent v2
The effect of containing 05 is as follows: dielectric thickness: 112 μm, internal electrode overlap dimension: 12 mm x O-7 mm, number of dielectric layers: 19
1 is a graph showing the electrical characteristics of a multilayer ceramic capacitor having a mN structure.

Claims (1)

[Claims] General formula xBaO-yTiO_2-z(Re_(_1_-_C_
) Me_C) O_3_/_2 (where x+
y+z=1.00, 0.01≦C≦0.20Re is L
At least one rare earth element selected from a, Pr, Nd, and Sm. Me is at least one rare earth element selected from rare earth elements excluding La, Pr, Nd, and Sm. ), x, y, z are the points a, b, c, d,
Vanadium oxide was added as a subcomponent to 100 parts by weight of the main component consisting of the molar ratio range surrounded by e and f.
A dielectric ceramic composition containing 0.005 to 2.000 parts by weight calculated as _5. ▲Contains mathematical formulas, chemical formulas, tables, etc.▼