JP3223341B2 - Dielectric porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric porcelain composition, and more particularly, to a high frequency dielectric porcelain composition mainly used in a microwave band for forming a resonator, a filter, a capacitor and a circuit board. .

[0002]

2. Description of the Related Art In recent years, high frequency dielectric porcelains have been used for filters, duplexers, and voltage controlled oscillators (VCOs) in wireless communication devices such as automobile phones, mobile phones, and cordless phones.
It is widely used for resonators used in devices and the like, or capacitors and substrates used in various high-frequency circuits.
For example, in a resonator or the like, by using a high dielectric constant material, the wavelength of a high frequency wave is shortened to the length of ε _r ^-1/2 (ε _r : relative dielectric constant) in a vacuum, and one wavelength at such a frequency is reduced. It is generally known that a microwave having a half wavelength or a quarter wavelength is confined in a dielectric ceramic for high frequency and configured to be small in size so as to obtain a predetermined effect.

On the other hand, the microwave band mainly used at present is around 1 GHz for consumer devices, but even in a higher frequency band (1 to several GHz) due to an increase in the amount of information and a higher speed of device operation. There is a need for available microwave electronic components. Therefore, as a dielectric ceramic composition constituting such a microwave electronic component, a material having a particularly large Q value, that is, a material having a small dielectric loss is required in order to minimize microwave loss.

[0004] Conventionally, as the above-mentioned dielectric porcelain composition,
Such as those of the MgTiO ₃ -CaTiO ₃ system is known. In this MgTiO ₃ -CaTiO ₃ based dielectric ceramic composition dielectric ceramic composition comprising a mixed crystal of MgTiO ₃ and CaTiO _3, MgTiO _3: CaTiO ₃ (molar ratio) (97-92) :( 3 8), the relative dielectric constant (ε _r ) is 19 to 22, and the fQ value is 10
Tens of thousands to tens of thousands GHz, temperature coefficient of resonance frequency (τ _f )
Since it can be adjusted in the range of 30 to +30 ppm / ° C., it is known as a dielectric material having excellent temperature characteristics and a high Q value.

However, this MgTiO ₃ -CaT
In producing the iO ₃ -based dielectric porcelain composition, MgO and TiO ₂ , and CaO and TiO ₂ were respectively reacted in advance to synthesize MgTiO ₃ having an ilmenite structure and CaTiO ₃ having a perovskite structure, and then synthesized. MgTiO ₃ and CaTiO ₃ must be mixed at a predetermined molar ratio and fired, and the number of steps is large, so that there is a problem that the manufacturing cost is necessarily increased.

To overcome this problem, Japanese Patent Publication No.
No. 14,605, the molar amount of MgO is TiO 2
MgTiO ₃ —CaTiO ₃ having a composition larger than the molar amount of ₂ and to which a predetermined amount of CaO or SrO is added
Based porcelain compositions have been proposed. However, even in the MgTiO ₃ -CaTiO ₃ based dielectric porcelain composition having such a composition, the firing temperature in the actual manufacture 135
There was a problem that the production cost was high because of the relatively high temperature of 0 to 1450 ° C.

In Japanese Patent Application Laid-Open No. Hei 5-24914,
It consists only of a mixed crystal of MgTiO ₃ and CaTiO ₃ ,
A dielectric porcelain composition free of O, CaO and TiO ₂ is disclosed. This aims to develop a high Q value, but the firing temperature is also 1 in this composition.
The temperature is as high as 350 to 1425 ° C, and the Q value cannot be said to be a sufficiently high value.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a dielectric ceramic composition which can be fired at a low firing temperature and has a high Q value. It is intended to be.

[0009]

The gist of the present invention resides in the following dielectric ceramic compositions (1) and (2).

(1) A dielectric porcelain composition characterized in that the composition formula is represented by the following formula:

(Mg _1-x Ca _x ) (Ti _1-y Ge _y ) O ₃ ... Where x ≦ 0.110 <y ≦ 0.15 (2) The composition formula is represented by the following formula: A dielectric ceramic composition containing the composition as a main component, wherein B is 0.10 mol or less in terms of B ₂ O ₃ and Zn is 0.50 mol or less in terms of ZnO, based on 1 mol of the main component. A dielectric porcelain composition characterized by being contained in a proportion.

(Mg _1-x Ca _x ) (Ti _1-y Ge _y ) O ₃ , where x ≦ 0.110 <y ≦ 0.15

[0013]

The dielectric ceramic composition according to the above (1) has a (M
g, Ca) a TiO ₃ -based porcelain composition containing Ge, wherein (Mg _1-x Ca _x ) (Ti _1-y Ge _y ) O ₃ (where x and y are each x ≦ 0 .11 and 0 <y ≦
(Value in the range of 0.15).

In the above composition formula, x is the atomic ratio of Ca to the total amount of Mg and Ca. When x exceeds 0.11, the Q value of the dielectric ceramic composition becomes small.
≦ 0.11. The lower limit is not particularly defined, but is preferably set to 0.03 so that the temperature coefficient (τ _f ) of the resonance frequency does not become too large on the negative side.

Further, y is G with respect to the total amount of Ti and Ge.
The inclusion of Ge in the atomic ratio of e significantly lowers the sintering temperature of the dielectric ceramic composition and improves the Q value. However, when Ge is excessively contained in excess of 0.15, the Q value is reduced as compared with the case where Ge is 0.15 or less.
Is a value within the range of 0 <y ≦ 0.15.

The above-mentioned dielectric ceramic composition of the present invention has a low firing temperature at the time of manufacture and has a Q value equal to or higher than that of a conventional dielectric material.

The dielectric porcelain composition according to the above (2),
It is mainly composed of the dielectric porcelain composition according to the above (1) (the dielectric porcelain composition represented by the above composition formula). _Two
The composition contains 0.1 mol or less in terms of O ₃ and 0.5 mol or less in terms of ZnO. Either B ₂ O ₃ or ZnO may be 0, that is, may not be contained.

Although the sintering temperature is lowered by containing B, if the content exceeds 0.1 mol, the deterioration of the Q value becomes remarkable. Dielectric ceramic composition represented by the following composition formula): 1 m
ol is converted to B ₂ O ₃ to 0.1 mol or less. Further, when Zn is contained, the sintering temperature is lowered and the Q value is improved. However, when the content exceeds 0.5 mol, the Q value is reduced as compared with the case where the content is 0.5 mol or less, so the content is determined as described above for the main component (the dielectric material represented by the above composition formula). 0.5 mol or less in terms of ZnO per 1 mol of the porcelain composition).

The dielectric ceramic composition of the above (2) also has a low firing temperature, and the Q value is equal to or higher than that of a conventional dielectric material.

[0020]

EXAMPLES Examples and comparative examples of the dielectric ceramic composition according to the present invention will be described below.

First, MgO powder, CaCO ₃ powder, TiO ₂ powder, GeO ₂ powder, B ₂ O ₃ powder and Z
used nO powder as a raw material, these raw materials, said _{(Mg 1- x Ca x) (} Ti 1-y Ge y) x in O ₃ type and y, as well as the content of B ₂ O ₃ and ZnO content Each was weighed so as to have various values including the range defined in the present invention, and charged into a pot mill, and wet-mixed.

Next, after drying this mixture, 950
Calcination was performed at 〜1150 ° C. for 1 to 3 hours, and the calcined product was wet-crushed with a pot mill. Next, the obtained slurry was dried, and after adding an appropriate amount of an organic binder (PVA) and sizing, the diameter was 20 m at a pressure of 1 to ² ton / cm ^2.
m, and formed into a cylindrical shape having a thickness of 10 mm.

The molded body is placed in the air at 110 to 1400.
Firing was performed at a temperature in the range of 1 to 3 hours to obtain a dielectric ceramic composition.

With respect to the cylindrical dielectric porcelain composition obtained by the above method, the relative dielectric constant (ε _r ) at a resonance frequency of 6 to 7.5 GHz, the Q value, and the temperature coefficient of the resonance frequency at −20 to + 80 ° C. (Τ _f ) was measured by the cylindrical resonator method. Since the Q value changes depending on the measurement frequency, it is represented by an almost constant fQ value.

The measurement results are shown in FIGS.

FIG. 1 shows (Mg _1-x C a _x ) (Ti _1-y G
e _y ) O ₃ -based dielectric porcelain composition (y is 0 or 0.03)
FIG. 6 is a diagram showing the effect of x on the fQ value, ε _r and τ _f of the above, that is, the effect of the Ca substitution amount on Mg. When x ≦ 0.11, the fQ value showed a large value of 50,000 GHz or more.

FIG. 2 shows (Mg _1-x Ca _x ) (Ti _1-y G
e _y ) O ₃ -based dielectric porcelain composition (x is 0.05, 0.0
7 is a diagram showing the effect of y on the fQ value, ε _r, and the firing temperature, ie, the effect of the amount of Ge substitution on Ti. If 0 <y ≦ 0.15, G
The fQ value is larger than when y = 0 where e is not included,
In addition, the firing temperature is 250 ° C. at the maximum compared to the case where y = 0.
More than a drop.

FIG. 3 shows (Mg _0.93 Ca _0.07 ) (Ti _1-y
Ge _y ) O ₃ + aB ₂ O ₃ based dielectric ceramic composition (y is 0
FIG. ₃ is a diagram showing the effect of the amount of B ₂ O ₃ added on the fQ value and the firing temperature of 0.03). B ₂ O ₃ is (Mg _0.93 Ca _0.07 ) (Ti _{1- y} Ge _y ) O ₃ 1 mol
If the fQ value is contained in the range of 0.10 mol or less, the firing temperature is lowered while the fQ value is maintained at a relatively high value, as compared with the case where it is not contained. In particular, as inferred from the measured values when y = 0 where Ge is not included, Ti
Is remarkable when the amount of Ge substitution with respect to
℃ fell.

FIG. 4 shows (Mg _0.93 Ca _0.07 ) (Ti _{0.94
Ge 0.06) + aB 2 O 3} + bZnO based dielectric ceramic composition (a showed the effect of B ₂ O ₃ and ZnO amount for fQ value or firing temperature of the) and 0,0.01 or 0.10 Figure It is. (Mg _0.93 Ca _0.07 ) (Ti _1-y Ge
_y) O ₃ B ₂ O ₃ with respect to 1mol are included below 0.10 mol, if the further ZnO is contained below 0.50 mol, fQ value is improved as compared with the case where ZnO is not contained, yet the baking temperature is Dropped. 0 mol of B ₂ O ₃
(When a = 0 in the figure), that is, when not included,
Although the effect of improving the fQ value was slightly small, similar results were obtained.

[0030]

MgTiO ₃ -CaTiO ₃ based dielectric ceramic composition of the present invention exhibits can be fired at low temperatures compared to ceramic compositions proposed in the prior art, a sintering temperature conventional 1400
The temperature can be lowered from about 250C to about 250C or more.
In addition, the Q value is the same or higher, and it is extremely useful as a dielectric ceramic composition for high frequencies.

[Brief description of the drawings]

FIG. 1 shows the relationship between the fQ value, ε _r and τ _f of (Mg _1-x Ca _x ) (Ti _1-y Ge _y ) O ₃ based dielectric ceramic composition.
It is a figure which shows the influence of (Ca substitution amount with respect to Mg).

Shows the effect of y (Ge substitution amount for Ti) with respect to FIG. 2 _{(Mg 1-x Ca x)} fQ value of _{(Ti 1-y Ge y)} O 3 based dielectric porcelain composition, epsilon _r and the firing temperature FIG.

FIG. 3 (Mg _0.93 Ca _0.07 ) (Ti _1-y Ge _y ) O ₃
System dielectric ceramic composition (y is 0 or 0.03) is a diagram showing the effect of B ₂ O ₃ added amount for fQ value and firing temperature.

[4] _{(Mg 0.93 Ca 0.07) (Ti} 0.94 Ge 0.06) based B ₂ O for fQ value and the firing temperature of the dielectric ceramic composition
FIG. ₃ is a diagram showing the effect of ₃ and the amount of ZnO added.

Claims (2)

(57) [Claims] 1. A dielectric porcelain composition characterized in that the composition formula is represented by the following formula. (Mg _1-x Ca _x ) (Ti _1-y Ge _y ) O ₃ where x ≦ 0.110 <y ≦ 0.15 2. A dielectric ceramic composition comprising a composition represented by the following formula as a main component:
1. A dielectric porcelain composition characterized by containing B in an amount of 0.10 mol or less in terms of B ₂ O ₃ and Zn in an amount of 0.50 mol or less as ZnO. (Mg _1-x Ca _x ) (Ti _1-y Ge _y ) O ₃ where x ≦ 0.110 <y ≦ 0.15