JPS61250904A - High dielectric ceramic composition and manufacture thereof - 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 [Technical Field of the Invention] The present invention relates to a high dielectric constant ceramic composition and a method for producing the same. The present invention relates to a high dielectric constant ceramic composition having a small temperature change in dielectric constant and a method for manufacturing the same.

[Technical background of the invention and its problems] The electrical properties required of a dielectric material include dielectric constant, temperature coefficient of dielectric constant, dielectric loss, dependence of dielectric constant on electric field, capacitance-resistance product, etc.

In particular, the capacitance-resistance product (OR value) needs to take a sufficiently high value; It is stipulated.

Furthermore, it must maintain a high capacitance-resistance product even at high temperatures (for example, the U.S. Department of Defense standard MIL-C-55681B stipulates a CR value of 125°C) so that it can be used under more severe conditions. is required.

In addition, stable temperature characteristics may be required over a particularly wide range of temperature ranges, for example, FiIA (Electronic Industries Association) standard X7R characteristic C: -55°C to +125°C.
The change in capacitance in the temperature range (2) is specified to be within ±154.

Furthermore, 1: When a multilayer type element is considered, since the electrode layer and the dielectric layer are integrally fired, it is necessary to use a stable π material even at the lI dielectric material firing temperature as the electrode material. Therefore, the firing temperature of the dielectric material is high.
It is necessary to use an expensive material such as Pd, and it is required to be able to fire at a low temperature of about 1100° C. or lower so that an inexpensive material such as Ag can be used.

As a conventionally known high dielectric constant ceramic composition, there is one in which a titanium-barium paste is used as a solid solution of stannate, zirconate, titanate, etc.

However, the firing temperature of barium titanate-based materials is 120
The temperature is as high as about 0 to 1400° C., and it is necessary to use an expensive material such as platinum or palladium that can withstand high temperatures as the electrode material, which causes high costs.

In order to solve the problems of barium titanate, various compositions have been studied. For example, the one mainly composed of iron and lead niobate (Japanese Patent Application Laid-Open No. 57-57204), and the one mainly composed of magnesium and lead niobate (Japanese Patent Application Laid-Open No. 55-1983).
51759), one mainly composed of magnesium/lead tungstate (Japanese Patent Application Laid-Open No. 144609/1982), and one mainly composed of magnesium/iron/lead tungstate (Japanese Patent Application Laid-Open No. 513-217462).

However, the dielectric constant is high, and the temperature change is -5
Wide temperature range C: 5°C to +125°C: Electrical characteristics such as extremely small temperature and high insulation resistance (
At present, a high dielectric constant ceramic composition that is excellent and can be sintered at low temperatures has not been obtained.

[Objective of the Invention] The present invention has been made in consideration of the above points, and provides a high-permittivity porcelain composition that has a high dielectric constant and insulation resistance, has a small temperature change in the dielectric constant, and can be sintered at low temperatures. The purpose is to provide products and their development methods.

[Summary of the invention] The present invention is based on the general formula %formula%] Represented by nine o'clock 0.35≦X+7≦0,6 0.3 ≦X ≦0.5 0.05≦y≦0.15 0.4 ≦ 2 ≦0.6 This is a high dielectric constant ceramic composition that satisfies the following.

Various types of perovskite ceramic materials have been studied as dielectric materials, but when Pb (ZnlqNbty,)OB is used as porcelain,
It has a perovskite structure and was thought to be unsuitable as a dielectric material (NECRa5earc
h & Development No. 29 people pr
il 1973 p. 15-21). According to research C2 conducted by the present inventors, Pb(ZnHNbq
) It was found that by replacing the Pb site of 06 with an appropriate amount of 8r, a stable peskite structure could be formed in porcelain. Furthermore, it has been found that such a porcelain composition exhibits a very high dielectric constant and an absolute resistance, and its temperature characteristics are extremely good.

Below, C: The composition range of the composition of the present invention will be explained.

First, regarding Pb substitution elements B1 and 8r, a small amount of substitution can form a perovskite structure, but (x+y) is 0.
．． If it is less than 35, it is difficult to reduce the temperature change in dielectric constant over a wide temperature range. Moreover, if (x+y) exceeds 0.6, the firing temperature will become high. As for xeY, if it is out of this range, the temperature change in dielectric constant becomes large. If it exceeds 20.6, the firing temperature will become high, and if it is less than 0.4, the temperature change in dielectric constant will become large.

If X, Y, and 2 are limited to the above ranges, then the dielectric constant is large and the temperature range is wide (the carbonization of the dielectric constant is small, the insulation resistance is high, and the temperature range is 1150°C).
A porcelain composition can be obtained which can be sintered at a low temperature of about 100%.

In addition, the composition of the present invention is composed of "(Pbl-(x+y)Bax8'y)[(ZnHNbq
)1-, Ti, and Co03, but the stoichiometric ratio may be slightly different. When this composition is converted into oxide, PbO32,14~49.94 wt BaO15
,46=28.34 wt%8rO1,74-
5,80wt$ ZnO4,01-s, 91 wtl NblOs 13.10 - 19.32 wt%
Ties is 10.74 to 17.88 wt%.

However, there may be impurities within a range that does not affect the effectiveness of the present invention.

It does not matter if additives or the like are included. For example, La1OB, M
n01゜Cod, Nip, Mg0.8b@OB, Z
Examples include transition metals such as rO2 and 7fi7 elements.

The content of these additives is about 1 wt at most.

The composition of the present invention is prepared as follows.

Pb, Ba, 8r, Zn, Nb as starting materials
Weigh Ti oxides or salts such as carbonates and oxalates, hydroxides, organic compounds, etc. that become oxides upon calcination in a predetermined ratio, thoroughly mix them, and then perform C second calcination. .

This calcination is performed at about 700°C to 850°C. If the calcination temperature is too low, the sintered density will decrease, and if it is too high, the sintered density will also decrease and the insulation resistance will decrease. Next, the calcined product is crushed to produce raw powder ice. Average particle size is 0.8-2
The diameter is preferably about μm; if it is too large, carbon pores in the sintered body will increase, and if it is too small, the moldability will deteriorate. Using such raw material powder, it is molded into a desired shape (; and then fired (-).
A ceramic with a high dielectric constant is obtained. By using the composition of the present invention, firing can be performed at 1150°C or less, 1000-1
It can be carried out at a relatively low temperature of about 100°C.

° The above-mentioned general method (-Alternatively, a raw material containing at least BaT10B powder as the raw material powder and other components may be mixed and fired. Such method 6; In the dielectric constant ceramic composition, the range of temperature change in dielectric constant is further reduced.

This manufacturing method is carried out as follows. A precipitate or calcined C of Ba and Ti, which are the components constituting 0g of BaT1 out of the starting materials; a carbonate that becomes more of an oxide.

Salts such as oxalates, hydroxides, organic compounds, etc. were prepared in advance so that the chemical formula 1 of BaT10B was obtained.
Calcinate at ~1350°C. At this time, it does not matter if the stoichiometric ratio deviates slightly. This calcined powder and other starting materials are weighed at a predetermined ratio and thoroughly mixed and pulverized. In addition.

In this case, other starting materials (which may contain Ba and TI) are preferably mixed and calcined at about 700-850°C. It does not matter if small amounts of other elements are included.

A high dielectric constant ceramic composition is obtained by molding the sufficiently mixed and pulverized powder into a desired shape and then firing it.

When manufacturing a laminated type element, the raw material powder or the powder C after mixing and pulverization; add a binder, a solvent, etc. to form a slurry, form a green sheet, print internal electrodes on this green sheet, and then It is manufactured by laminating and pressing a number of sheets and firing them. At this time, since the dielectric material of the present invention can be sintered at low temperatures, it is possible to use, for example, an inexpensive material mainly made of carbon as the internal electrode material.

Furthermore, since it can be fired at such a low temperature, it is also effective as a material for thick film hyperelectric paste to be printed and fired on circuit boards, etc.

Such a ceramic composition of the present invention has a high dielectric constant and good temperature characteristics. In addition, the CR value is large, and special C: high-
However, the reliability at high temperatures is excellent.

Furthermore, the dielectric constant bias electric field dependence is excellent, and g
Even with KV/wm, it is possible to obtain materials with a draft quality of 10% or less. Therefore, it is effective as a material for high pressure.

It has low dielectric loss and is effective for AC and high frequency applications.

Furthermore, as mentioned above, the temperature characteristics of the dielectric constant are excellent, so even when applied to electrostrictive elements, it is possible to obtain elements with small temperature changes in displacement.

Furthermore, since the grain size during firing is made uniform to 1 to 3 μm, the pressure resistance is also excellent.

The electrical properties C were described above, and the mechanical strength was also sufficient C: excellent.

[Effects of the invention] As explained above, according to the present invention #4 (:), it is possible to obtain a high dielectric constant porcelain composition which has a high dielectric constant and has excellent temperature characteristics and bias characteristics.41?ζ Since porcelain with such various characteristics can be obtained by firing at low temperatures, it is suitable for application to multilayer ceramic elements such as multilayer ceramic capacitors and multilayer ceramic displacement generating elements.

[Embodiments of the invention] The present invention will be explained in detail below.

(Examples 1 to 5) Pb, Ba, 8r, Zn, Nb as starting materials
, Starting materials such as Ti oxide are mixed in a ball mill or the like, and calcined at 70°C to 850°C. Next, this calcined body was crushed with a ball mill or the like, and after drying, a binder was added and granulated, and pressed to form a disc-shaped body with a diameter of 17M and a thickness of about 2 mm. As balls for mixing and grinding, it is preferable to use balls with high hardness and high toughness, such as partially stabilized zirconia balls, in order to prevent contamination of impurities.

This element body was sintered in air at 1000-1100°C for 2 hours, and the characteristics of both main surfaces (silver electrodes were sintered) were measured. The dielectric loss and capacity were 1 kHz, 1 V rms.
This is the value measured by a digital LCR meter at 25°C, and the dielectric constant is calculated from this value. In addition, the insulation resistance was calculated from the value measured using an insulation resistance meter after applying Zoo V voltage for 2 minutes. Note that the temperature characteristics of the dielectric constant are based on the value of 25°C, and range from -55°C to +125°C.
Temperature range C in °C: Expressed by the maximum and minimum values of the range of change. The capacitance-resistance product was determined from (permittivity) x (insulation resistance) x (vacuum permittivity) at 25°C and 125°C. Insulation resistance measurements were performed in silicone oil to exclude the effects of atmospheric moisture.

The results are shown in Table 1.

Reference example 4 is outside the scope of the composition of the present invention.

(Examples 6-7) Among the starting materials, Ba is a component constituting BaT10B.
and Ti oxide or calcined (di-oxide C;
Salts such as carbonates and oxalates, and hydroxides.

Organic compounds, etc. are weighed in advance so that the chemical formula is BaTl0B, and mixed using a ball mill etc.
Calculate at 0℃. On the other hand, other Pb, 8r, Z
Mix oxides such as n, Nb, or oxides C: salts such as carbonates and oxalates, hydroxides, organic compounds, etc. in a ball mill 1 etc. to 700 to 8
Calculate at 50℃. Next, these calcined bodies are weighed so as to have a predetermined ratio of g:C, and thoroughly mixed and ground. Similar to Examples 1 to 5, samples were prepared and the results are shown in Table 1 (
:show.

As is clear from Table 1 below, the ceramic compositions of the present invention (Examples 1 to 5) have a high dielectric constant (K = 3000 or more) and
Good temperature characteristics (within ±15% at -55 to +125℃)
It is. The CR value is also large, at 4000 Ω·μP (at 25°C) or higher, and is 4.100100 O/P or higher at 125°C, and the reliability at high temperatures is excellent.

Furthermore, it has an excellent (nil electric bias electric field dependence of 4bIKV/■ within 15cm).Also, the dielectric loss is 1k at 25℃.
It is small at 2.0% or less in Hz.

Although the reference example does not contain the 8r component, the capacitance-resistance product is small and the range of change in dielectric constant is large. Further, although Reference Example 2 contains a predetermined amount of Sr component, the amount of Bs and TI is small, so that the range of change in dielectric constant becomes large.

Dew 1 Figure C: Shows the temperature characteristics of dielectric constant. For comparison, (B
aTiOs) o, oys-(NbsOs) o, ol? −
(TasOa) o, ooa - (NdsOs) o, oo
The characteristics of barium titanate-based materials of s are also shown (
Reference example 3). Reference example 3 has a temperature change range of dielectric constant of 155°C.
The dielectric constant is within ±15 inches at ~+125°C, which is good, but the dielectric constant at 25°C is about 2000, which is small. Further, the firing temperature of Reference Example 3 is 1200 to 1220°C, which is relatively high.

(On the other hand, in the present invention, the range of temperature change in dielectric constant is within ±15% from 5°C to +125°C, and 2
The dielectric constant at 5°C is as high as 4000 (Example 3).

Furthermore, as is clear from Table 1, when the method for producing the ceramic composition of the present invention is used, the change in dielectric constant is reduced, while other properties remain unchanged.

FIG. 2 is a diagram showing the DC bias electric field dependence. In general, the dielectric constant tends to decrease as the bias electric field increases, and this tendency becomes more pronounced as the dielectric constant increases. Reference example 3 has a dielectric constant of about 2000, but l K
-7 in V/m, 2KV/m TE 20% J-Very shows a large decreasing trend. In contrast, in Example 3, despite C2 having a large dielectric constant of 4000,
□2 KV/wa is about 10'j C1flj['
No.

As described above, the composition of the present invention having a small dependence on a DC bias electric field is effective as a material for a high-voltage capacitor. Maku,
When considering a multilayer capacitor, in order to increase the capacitance with the same shape, it is necessary to make the dielectric layer even thinner, but in this case, the electric field applied to the skin becomes higher ( However, since the composition of the present invention has excellent bias characteristics, the characteristics do not deteriorate even when applied to such devices.

Figure 3 (shows the temperature characteristics of two OR values. In the case of the present invention,
Even at high temperatures, the CR value decreased slightly, with Example 6 at 2100 MΩ・μF (125°C) and Example 7 at 380
It shows a very high value of 0MΩ・μF (125℃), and the reliability is excellent.In contrast, Reference Example 3 shows a high value of 4000MΩ・μF#!4 degrees at room temperature. , at 125° C., the C value drops to 100 MΩ·μF.

FIG. 4 is an X-ray diffraction pattern diagram of Example 6, which shows a nearly perfect perovskite phase. Therefore, the dielectric constant is 3900. OR value 5400MΩ・μF (
(25℃) and 2100MΩ・μF (125℃).

Next, a multilayer ceramic capacitor was prepared using Example 64, which contained 5 mo1% of MnO and CoO, and nine examples will be described. First, BaT10B having such a composition and other roasted powders were thoroughly mixed, an organic solvent was added to form a slurry, and a 30 μm green sheet was created using a Tomago Dr. Plaid caster. On this green sheet (Yu80Aji/2
0Pd electrode paste was printed in a predetermined pattern, and 20 sheets having such an electrode pattern were laminated and pressure-bonded. After that, it is cut into a predetermined shape and degreased to a 1080mm
Firing was carried out under the conditions of ℃ and 2 hours. After sintering, λg paste is baked as an external electrode to produce a multilayer ceramic capacitor. Its electrical characteristics are shown in Table 2.

The dielectric constant of the obtained multilayer ceramic capacitor is approximately 400.
0, and Table 2 C: It can be seen that each characteristic is sufficiently excellent as C2 as a reminder. In particular, the temperature characteristics are -55℃~
It is within ±151 at +125°C, which satisfies the X7R% of EI people.

The high dielectric constant ceramic composition and the manufacturing method thereof according to the present invention 4 have various characteristics such as a large dielectric constant and a wide temperature range (:
Since it is possible to provide an excellent high dielectric constant ceramic composition, it is effective as a material and manufacturing method for Special C: Multilayer Ceramic Capacitors. In addition, in the production method of the present invention, a compound mainly containing zinc lead niobate and barium titanate was used, but the same effects as the present invention can be obtained even if other ingredients are used in place of these. i may be affected.

[Brief explanation of drawings]

Figure 1 is a diagram of the temperature characteristic curve of dielectric constant, Figure 2 is a diagram of the DC bias electric field characteristic curve of dielectric constant, Figure 3 is a diagram of the temperature characteristic curve of insulation resistance capacity building, and Figure 4 is a diagram of the composition according to the present invention. X-ray diffraction pattern diagram. Representative Patent Attorney Kensuke Nori Chika (and 1 other person) □ On IX (
#C) Fig. 1 DC Beias electric current 1 (((η Sochiku) Fig. 2 Temperature A C'C) Fig. 3 O Berodskite flat QtK 2θ (d91) Fig. 4

Claims (1)

[Claims] (1) General formula (Pb_1_−_x_−_yBa_xSr_y) [(Z
n_1_/_8Nb_2_/_8)_1_-_zTi_
z]O_8, it is characterized by satisfying the following: 0.35≦x+y≦0.6 0.3≦x≦0.5 0.05≦y≦0.15 0.4≦z≦0.6 High dielectric constant porcelain composition. (2) General formula (Pb_1_−_x_−_yBa_xSr_y) [(Z
n_1_/_8Nb_2_/_8)_1_-_zTi_
z] When expressed as O_8, a high dielectric material having a composition of 0.35≦x+y≦0.6 0.3≦x≦0.5 0.05≦y≦0.15 0.4≦z≦0.6 A method for producing a high dielectric constant ceramic composition, characterized in that at least BaTiO_8 powder is used as a raw material for producing the high dielectric constant ceramic composition.