JPH0940459A - Dielectric porcelain composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a dielectric porcelain composition capable of densifying it at a low burning temp. and also having good electrical characteristics. SOLUTION: 0.003-0.035pt.mol. Bi (expressed in terms of Bi2 O3 ), 0.0005-0.0050pt. mol. Mn (expressed in terms of MnO2 ), 0.002-0.040pt.mol. Ag (expressed in terms of Ag2 O) and 0.005-0.04pt.mol. B (expressed in terms of B2 O3 ) are incorporated in a fundamental composition expressed by the formula, (Ba1-x Znx )O.n(Ti1-y Siy ) O2 (where 0.05<=x<=0.25, 0.01<=y<=0.15, 3<=n<=6) based on 1 mol of the fundamental composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric ceramic composition, specifically a dielectric ceramic composition suitable for use in a laminated capacitor, a laminated LC filter, a dielectric resonator and the like.

[0002]

2. Description of the Related Art As a conventional dielectric ceramic composition used for a dielectric resonator or the like, for example, JP-A-57-69 is known.
No. 607, a dielectric material obtained by adding 1-26 wt% ZnO to 100 wt% of a composition of 3.9 ≦ x ≦ 4.1 in BaO—xTiO ₂ and mixing and firing the mixture. Porcelain compositions are known.

[0003]

However, in the conventional dielectric ceramic composition described above, if the firing temperature is as high as 1200 ° C., it is difficult to obtain a dense ceramic, and the electric characteristics are likely to vary. Therefore, an object of the present invention is to provide a dielectric ceramic composition that can be densified at a low firing temperature and that has good electric characteristics.

[0004]

The dielectric ceramic composition of the present invention has the general formula (Ba _1-x , Zn
_x ) O.n (Ti _1-y , Si _y ) O ₂ (however, 0.05
≦ x ≦ 0.25, 0.01 ≦ y ≦ 0.15, 3 ≦ n ≦
Bi to Bi ₂ with respect to 1 mol of the basic composition represented by 6).
0.003 to 0.035 mol part in terms of O ₃ , Mn is Mn
0.0005 to 0.0050 parts by mole O ₂ terms, 0.002 to 0.040 part by mol of Ag with Ag ₂ O in terms of the B B
It is characterized by containing 0.005 to 0.040 parts by mol in terms of ₂ O ₃ .

The reason for limiting the composition range of the basic composition as described above is as follows. When n is smaller than 3 or larger than 6, densification does not occur by firing at 950 ° C. or lower. Further, when x is less than 0.05, densification does not occur by firing at 950 ° C. or less, and when it exceeds 0.25, the Q value is low, a resonance point cannot be found, and the resistivity deteriorates. Further, if y is less than 0.01, densification will not be achieved by firing at 950 ° C. or lower, and if it exceeds 0.15, the Q value will be low, a resonance point will not be found, and the resistivity will deteriorate. .

The reason why the composition ranges of the Bi, Mn, Ag and B components are limited as described above is as follows. If Bi is smaller than 0.003 mol part in terms of Bi ₂ O ₃ , it will not be densified by firing at 950 ° C. or lower, and will be 0.03
When it exceeds 5 mol parts, the Q value is low, the resonance point cannot be found, and the resistivity is deteriorated. Further, if Mn is less than 0.0005 parts by mol in terms of MnO ₂ , it will not be densified by firing at 950 ° C. or less, and if it exceeds 0.0050 parts by mol, the Q value will be low and no resonance point will be found. Resistivity deteriorates. Further, when Ag is less than 0.002 parts by mole in terms of Ag ₂ O, densification does not occur by firing at 950 ° C. or less, and when it exceeds 0.040 parts by mole, the Q value is low and no resonance point can be found. At the same time, the resistivity deteriorates. Also, B is B
_{This is because if} it is less than 0.005 mol part in terms of ₂ O ₃ , it will not be densified by firing at 950 ° C. or less, and if it exceeds 0.040 mol part, the Q value will be low and no resonance point will be found.

[0007]

EXAMPLES The present invention will be described below based on Examples and Comparative Examples. First, BaCO ₃ and TiO ₂
Are calculated with Ba and Ti, and equimolar amounts are weighed,
These were dispersed in a ball mill using ZrO ₂ beads and water as a dispersion medium and wet-mixed. Then, this mixture is dehydrated and dried, and then in air at 800 to 1200 ° C.
It was calcined for 4 hours. This calcined product was dispersed under the same conditions as the above dispersion and wet-milled, and it was confirmed by SEM observation and particle size distribution analyzer that the pulverized particles thus obtained were uniform particles of 0.3 μm or less, followed by dehydration, It was dried to obtain a powder.

Then, the above powder and TiO ₂ , ZnO, S
iO ₂ , MnO ₂ , Bi ₂ O ₃ , Ag ₂ O and B ₂ O
₃ was weighed so as to have a predetermined ratio as shown in Table 1 below, wet-mixed in a ball mill in the same manner as above, dehydrated and dried, and then in air at 600 ° C to 9 ° C.
It was calcined at 00 ° C for 4 hours. This calcined product was wet pulverized, dehydrated and dried in the same manner as above. Next, polyvinyl alcohol was added to this dried product and granulated with a 60 mesh screen. Pack the granulated material in a mold and press 1 with a hydraulic press.
Molded into two sizes of 5 mmφ x height 1 mm and 15 mmφ x height 6 mm (molding pressure: 1-3 t / cm
² ), depending on the composition, it was fired in the air at a temperature in the range of 900 to 1200 ° C. to obtain a sintered body having each composition shown in Table 1 below. The degree of densification of the thus obtained sintered body was evaluated by an ink test. Next, 15 mmφ
The Ag electrode material paste was applied to both planes of a sintered body (disk shape) of a molded body that was molded to a height of 1 mm, and baked to form a silver electrode. This was used as a sample for measuring relative permittivity ε _r , temperature coefficient τ ε of capacitance, and resistivity.

[0009]

[Table 1]

In Table 1 above, the samples without * indicate examples having compositions within the scope of the present invention, and the samples with * have compositions outside the scope of the present invention. It shows a comparative example. The electrical characteristics of the electrode-attached sample obtained as described above were measured. Relative permittivity ε
_r was measured using an LCZ meter under the conditions of 25 ° C. and 1 MHz. In addition, the temperature coefficient of capacitance τε (ppm /
℃), put these samples with electrodes in a constant temperature bath, change the temperature from 20 ℃ to 85 ℃, the capacitance at 20 ℃ (C ₂₀ ) as a reference, and the capacitance at 85 ℃ (C ₈₅ ) and calculated according to the following formula. Also,
The resistivity (Ω · cm) was calculated from the insulation resistance value of the sample measured at 150 ° C. and the sample size.

[0011]

[Equation 1]

Further, regarding the sintered body of the molded body molded into a size of 15 mmφ × height 6 mm, the waveform at the resonance point by the dielectric cylinder resonator method (measured at 25 ° C.) is used as the dielectric cylinder resonator. The Qf product was calculated from The resonance frequency was 3.5 to 4.5 GHz. The above evaluation results and measurement results are shown in Table 1 above. As is clear from these results, the dielectric ceramic composition of the present invention is
It is possible to densify at a firing temperature of 50 ° C. or less, and the sample with an electrode made from the obtained sintered body has a relative dielectric constant ε.
_{The r} , Qf product and resistivity were high.

In the above examples and comparative examples,
The composition of the sintered body is the result of ICP analysis of the sintered body after firing,
It was found that the composition was almost the same as the composition at the time of compounding. Also,
In the above embodiment, BaCO ₃ and TiO ₂ are mixed, calcined and crushed to obtain a raw material powder. Instead of this raw material powder, the starting material has a particle size of 0.3 μm or less. Similar results were obtained using commercially available BaTiO ₃ . In addition, BaCO ₃ , TiO ₂ , ZnO, SiO ₂ ,
MnO ₂ , Bi ₂ O ₃ , Ag ₂ O and B ₂ O ₃ may all be mixed together and calcined. Also, instead of MnO ₂ ,
It is also possible to use MnO, Mn ₃ O ₄ , MnCO ₃ , Mn (OH) _{2, and the} like. It is also possible to use Ag or the like instead of Ag ₂ O. Also, B ₂
Glass containing boron instead of O ₃ (for example, B ₂ O ₃
And glass selected from PbO, SiO ₂ , Na ₂ O, ZnO, etc.) and the like can also be used.

[0014]

As described above, according to the dielectric ceramic composition of the present invention, the basic composition containing Bi, Mn, Ag and B in a certain amount has a low firing temperature of 950 ° C. or lower. Since it can be densified, it is possible to reduce the power cost, the cost of the furnace material, the sheath, the setter and the like, and it is also possible to use inexpensive Cu, Ag and the like as the electrode. Particularly considering the use in a high frequency region (GHz band), Ag is a conductor material having a low resistivity as is well known, and therefore it is very significant that it can be integrally fired with an Ag conductor.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Koichi Koichi 6-16-20 Ueno 6-16 Ueno, Taito-ku, Tokyo

Claims (1)

[Claims] 1. A general formula: (Ba _1-x , Zn _x ) O.n
(Ti _1-y , Si _y ) O ₂ (where 0.05 ≦ x ≦ 0.
25, 0.01 ≦ y ≦ 0.15, 3 ≦ n ≦ 6), based on 1 mol of the basic composition, Bi was calculated to be 0.2 in terms of Bi ₂ O ₃ .
003 to 0.035 mol part, and Mn of MnO ₂ conversion of 0.
0005 to 0.0050 parts by mole, Ag 0.002 to 0.040 parts by mole in terms of Ag ₂ O, and B 0.1% in terms of B ₂ O ₃ .
A dielectric ceramic composition containing 005 to 0.040 parts by mol.