JP2003292373A - Dielectric porcelain composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a dielectric porcelain composition for a high-frequency, which constitutes a resonator, a dielectric substrate, or the like, used in a microwave region, and which has a high specific dielectric constant preferable from the view point of environmental protection and is sintered at a relatively low temperature. <P>SOLUTION: The main component of the composition is expressed by the formula: xBaO-y[(1-a)Nd<SB>2</SB>O<SB>3</SB>.aSm<SB>2</SB>O<SB>3</SB>]-zTiO<SB>2</SB>[wherein 14<x<18, 11<y<15, 67<z<75, 0.07<a<0.6 (preferably 0.4<a<0.6), and x+y+z=100% (molar ratio)]. Bi<SB>2</SB>O<SB>3</SB>of 10-20% (preferably 12-19%), Al<SB>2</SB>O<SB>3</SB>of 0.1-1.5% (preferably 0.4-1%), and MnO of 0.01-1.5% (preferably 0.1-0.2%), based on the main component, are contained as auxiliary components. Thus, the dielectric porcelain composition having a high quality coefficient, a low absolute value of the temperature coefficient of resonance frequency, and stable quality is obtained. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency dielectric porcelain composition which constitutes, for example, a resonator or a dielectric substrate used in the microwave region.

[0002]

2. Description of the Related Art In recent years, high frequencies have been used in antennas used in wireless communication devices such as car phones, mobile phones, cordless phones, resonators used in voltage controlled oscillators, filters used in cable TV tuners, etc. Dielectric porcelain for use is often used. By using a high dielectric constant material in such a resonator or the like, the high frequency wavelength is shortened to a length of εr ^{−1/2 in} a vacuum, and one wavelength, 1/2 wavelength or 1/4 wavelength at that frequency is reduced. It is generally known that a microwave of a wavelength is confined in a high-frequency dielectric ceramic and is miniaturized so as to obtain a predetermined effect. The characteristics required for such a high frequency dielectric porcelain include (1) the wavelength of the electromagnetic wave is ε in the dielectric.
Since the size is reduced to r ^-1/2 and the same resonance frequency makes the size smaller as the permittivity increases, the relative permittivity is as high as possible, and (2) the quality factor in the high frequency band is high,
(3) There are three reasons that the temperature change of the resonance frequency is small.

And it is assumed that these conditions are satisfied.
Japanese Patent Laid-Open No. 62-72558.
Una BaO-Nd₂O₃-TiO₂-Bi₂O₃System dielectric
Disclosed in body porcelain composition and JP-A-6-333425
Like PbO-Re₂ O₃-TiO₂-Bi₂O
₃A dielectric ceramic composition based on (Re is a rare earth metal) is proposed.
Has been.

[0004]

However, this has the following disadvantages.

First, the former (BaO-Nd ₂ O ₃ -TiO ₂
In (-Bi ₂ O ₃ -based dielectric ceramic composition), the relative dielectric constant is around 90, and the dielectric constant is small in order to further downsize the high frequency module. The latter (PbO-
Re ₂ O ₃ —TiO ₂ —Bi ₂ O ₃ -based dielectric ceramic composition) has a composition having a dielectric constant of 100 or more, but in recent years,
Considering the fact that the use of Pb is abolished from the viewpoint of environmental protection, it cannot be said that the composition is appropriate. Furthermore, in both cases, the firing temperature is 1300 to 1400 ° C., which is a fairly high temperature in most cases.

In view of such circumstances, the present invention has a high relative permittivity and is also preferable from the viewpoint of environmental protection, is sintered at a relatively low temperature, has a high quality factor, and has a low absolute value of the resonance frequency temperature coefficient. An object of the present invention is to provide a dielectric ceramic composition with stable quality.

[0007]

The present invention provides a compositional formula xBa.
O-y ((1-a) Nd ₂ O ₃ · aSm ₂ O ₃ ) -zTi
O ₂ (where 14 <x <18, 11 <y <15, 67
<Z <75, 0.07 <a <0.6 (preferably 0.
4 <a <0.6), x + y + z = 100% (molar ratio))
In respect to the main component expressed, the Bi ₂ O ₃ as an auxiliary component 10-20% (preferably, 12~19%), Al ₂ O
₃ to 0.1 to 1.5% (preferably 0.4 to 1%),
0.01 to 1.5% of MnO (preferably 0.1 to 1.5%)
0.2%).

Here, the reasons for limiting the composition of the main component are as follows. That is, if x is too large, the quality coefficient Q becomes small, and the resonance frequency temperature coefficient τf becomes large in the − side. On the other hand, if x is too small, the resonance frequency temperature coefficient τf becomes too large on the + side. Further, if y is too large, the relative permittivity εr becomes small, and if y is too small, the relative permittivity εr and the quality factor Q become small. If z is too large, the temperature coefficient of resonance frequency τf becomes large, and z
Is too small, the quality factor Q becomes small. If a is too small, the resonance frequency temperature coefficient τf becomes too large, and if a is too small, the relative dielectric constant εr becomes too small.

On the other hand, the reasons for limiting the composition of the subcomponents are as follows. That is, if the amount of bismuth oxide added is too large, the quality factor Q becomes small, and if the amount of bismuth oxide added is too small, the dielectric constant becomes too small. Further, if the added amount of aluminum oxide is too large, the relative dielectric constant εr becomes small, and if the added amount of aluminum oxide is too small,
The resonance frequency temperature coefficient τf becomes too large. If the amount of manganese oxide added is too large, the relative permittivity εr and the quality factor Q are small, and if the amount of manganese oxide added is too small, the sinterability is poor and the dielectric properties are not stable.

The unit "%" in the present specification represents a mass percentage unless otherwise specified.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

The dielectric ceramic composition according to the present invention contains a barium oxide.
Lithium, titanium oxide, neodymium oxide and summary
Contains barium as a main component, and these barium oxides and titanium oxides
Tan, neodymium oxide and samarium oxide respectively
BaO, TiO₂, Nd₂O ₃, Sm₂O₃Converted to
The main component is a composition formula xBaO-y ((1-a) Nd₂O₃・ A
Sm₂O₃) -ZTiO₂When expressed by, x + y + z =
Assuming 100% (molar ratio), each content is 14
<X <18, 11 <y <15, 67 <z <75, 0.0
7 <a <0.6 (preferably 0.4 <a <0.6)
It has become.

Then, bismuth oxide is added to the main component.
Sodium, aluminum oxide and manganese oxide are added. That
The added amount is bismuth oxide, aluminum oxide and
Bi and manganese oxide₂O₃, Al₂O₃And
When converted to MnO and Bi₂O₃But
10-20% (preferably 12-19%), Al₂O
₃Is 0.1 to 1.5% (preferably 0.4 to 1%),
MnO is 0.01 to 1.5% (preferably 0.1 to 1.5%).
0.2%).

Since the dielectric ceramic composition according to the present invention has the above-mentioned constitution, the firing temperature during production is 1250 to 1250.
At a relatively low temperature of 1290 ° C., the relative dielectric constant εr is 85 or more, the quality factor Q at 1 GHz is 2500 or more, and the resonance frequency temperature coefficient τf at −30 to 80 ° C. is 20 ppm or less in absolute value. A dielectric ceramic composition having stable characteristics can be obtained.

The dielectric ceramic composition of the present invention can be obtained by subjecting such a composition to treatments such as mixing, calcination, pulverization, kneading, molding and firing.

The raw material used here is not particularly limited, but it is usually preferable to also mix the raw material powder containing the metal component constituting each oxide. At this time, the raw material powder is an oxide or an oxide which is formed by subsequent firing. That is, it is usually selected from oxides, carbonates, hydroxides, etc., which contain the elements composing each of the above oxides. The average particle size of these raw material powders is 5 μm or less (preferably,
1 μm or less).

Such raw material powders are weighed and mixed so that the final composition becomes the above composition, but the mixing method and time are not particularly limited, and the method and time for sufficiently dispersing the components are selected.

The mixture thus obtained is dehydrated and dried by an appropriate method and then calcined. Further, the calcined product obtained by calcination is pulverized to an average particle size of about 0.5 to 3 μm. At this time, the pulverization method is not particularly limited, but wet pulverization may be used, for example.

About 1 to 4 parts by weight of a binder is added to 100 parts by weight of the powder after mixing and mixed,
Perform pressure molding. Polyvinyl alcohol or the like is generally used as the binder. Further, the pressure molding is performed, for example, by filling the powder obtained by mixing a binder or the like in a mold of an appropriate size and molding pressure of about 1 to 5 t / cm ² .

The firing may be carried out at a rate of temperature increase of about 50 to 300 ° C./h and a rate of temperature decrease of about 50 to 300 ° C./h for about 1 to 5 hours in an oxygen atmosphere such as the atmosphere.

Such a dielectric ceramic composition of the present invention is
It is used in the frequency band of about 100 MHz to 3 GHz. A typical application example is the Global Positioning System (G
The material of the resonator used for a PS) antenna, a voltage control oscillator, etc. can be mentioned. Further, it can be used as a microwave integrated circuit board and a high frequency capacitor material.

[0022]

EXAMPLES Examples of the present invention will be described below.

As the starting material, BaCO₃, TiO₂,
Nd₂O₃, Sm₂O₃, Bi₂O ₃, Al₂O₃, M
Sample whose final composition after sintering is shown in Table 1 using nO powder
Weigh each component powder to make the composition of the number, and
With zirconia spheres in a solvent
After wet mixing for a period of time, dehydration and drying are performed to obtain a mixture.
It was

[Table 1]

This mixture was calcined at 1000 to 1200 ° C. for 2 hours, and the obtained calcined product was wet-ground in a ball mill together with zirconia balls using water as a solvent.

Polyvinyl alcohol was added as a binder to the pulverized product thus obtained, and the mixture was mixed and granulated to give a diameter of 1
After pressure molding into a cylindrical shape of 3.8 mm and a height of 6 mm, 1
A dielectric ceramic was obtained by firing at 240 to 1290 ° C. for 3 hours only.

The dielectric ceramic thus obtained has a diameter of 11.
Processed to 5 mm and 5 mm in height, and sample numbers 1 to 1 respectively
7, each of the cylindrical dielectric ceramic samples was sandwiched between two parallel metals to form a resonator, and various characteristics were measured by the following methods. The results are shown in Table 1.

<Method of Measuring Dielectric Properties> The relative permittivity εr and the quality factor Q were measured by the dielectric resonator method. As the measuring instrument, a network analyzer made by Agilent: 8753ES was used.

<Measurement Method of Resonance Frequency Temperature Coefficient τf> The change of the resonance frequency f0 at the measurement temperature of −30 to 80 ° C. is measured by the dielectric resonator method, and the resonance frequency temperature coefficient τf is calculated by the formula shown in Formula 1. did.

[Equation 1]

Q in Table 1 is 1 GH using a relational expression f ₀ × Q = constant relation between the resonance frequency f ₀ and the quality factor Q.
The values are shown in terms of z.

The measurement results of the dielectric properties are shown in the examples of Table 1. In Table 1, the composition is represented by the composition formula of the main component xBaO-y ((1-a) Nd ₂ O ₃ · aSm.
₂ O ₃ ) -zTiO ₂ represents x + y + z = 10
0% (molar ratio), 0 to <a <1 and, with respect to the main component, as a subcomponent, expressed _{Bi 2 O 3, Al 2 O} 3, MnO and each mass percentage (%).

Here, the reason for limiting the composition of the present invention will be specifically described. When x is too large, the quality coefficient Q becomes small and the resonance frequency temperature coefficient τf becomes large toward the − side, as shown in Comparative Example 1. On the other hand, if x is too small, the resonance frequency temperature coefficient τf becomes too large on the + side, as shown in Comparative Example 2. Further, if y is too large, the relative permittivity εr becomes small as shown in Comparative Examples 3, 4, and 5,
And the firing temperature rises to 1300 ° C. If y is too small, as shown in Comparative Example 6, the relative permittivity εr and the quality factor Q
Both become smaller. Further, when a is too small, Comparative Example 7
As shown in (3), if the resonance frequency temperature coefficient τf becomes too large and a becomes too small, the relative dielectric constant εr becomes too small.

On the other hand, if the amount of bismuth oxide added is too large, the quality factor Q becomes small as shown in Comparative Examples 8 and 9, and if the amount of bismuth oxide added is too small, the dielectric constant becomes too small. Further, when the amount of aluminum oxide added is too large, the relative dielectric constant εr becomes small as shown in Comparative Example 10, and when the amount of aluminum oxide added is too small,
As shown in Comparative Example 11, the temperature coefficient τf of the resonance frequency becomes too large. Further, if the addition amount of manganese oxide is too large, as shown in Comparative Example 12, the relative dielectric constant εr and the quality factor Q are small, and if the addition amount of manganese oxide is too small, as shown in Comparative Example 13, sintering is performed. Properties deteriorate, the firing temperature rises, and the dielectric properties are not stable.

[0033]

As described above, according to the present invention,
Since barium oxide, titanium oxide, neodymium oxide, and samarium oxide were used as main components, and bismuth oxide, aluminum oxide, and manganese oxide were added to the composition,
Provided is a dielectric ceramic composition which has a high relative dielectric constant and is preferable from the viewpoint of environmental protection, is sintered at a relatively low temperature, has a high quality coefficient, has a low absolute value of the resonance frequency temperature coefficient τf, and has stable quality. It becomes possible, and 100MHz-3GH
It is particularly suitable as a dielectric ceramic material used at about z.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Emi Kunii             F-de, 5-36-1 Shimbashi, Minato-ku, Tokyo             K.K Co., Ltd. F-term (reference) 4G031 AA06 AA07 AA11 AA19 AA29                       AA35 BA09 GA02                 5G303 AA02 AB06 AB11 AB15 BA12                       CA01 CB01 CB03 CB05 CB22                       CB35 CB41                 5J006 HC07

Claims (2)

[Claims] 1. A composition formula xBaO-y ((1-a) Nd ₂
O ₃ · aSm ₂ O ₃ ) -zTiO ₂ (where, 14 <x
<18, 11 <y <15, 67 <z <75, 0.07 <
a <0.6, x + y + z = 100% (molar ratio)) with respect to the main component represented by Bi ₂ O ₃ as an auxiliary component
20%, Al ₂ O ₃ 0.1-1.5%, MnO 0.
A dielectric ceramic composition characterized by being contained in a proportion of 01 to 1.5%. 2. The composition formula xBaO-y ((1-a) Nd ₂
O ₃ · aSm ₂ O ₃ ) -zTiO ₂ (where, 14 <x
<18, 11 <y <15, 67 <z <75, 0.4 <a
<0.6, x + y + z = 100% (molar ratio)) to the main component represented by Bi ₂ O ₃ as a sub-component of 12 to 1
9%, Al ₂ O ₃ 0.4-1%, MnO 0.1-
A dielectric ceramic composition characterized by being contained in a proportion of 0.2%.