JPH0757540A - Dielectric porcelain composition and laminated dielectric part therewith - Google Patents

Abstract

PURPOSE:To provide a laminated dielectric part having a high dielectric constant and a high no-load Q value by overlapping multiple sheet dielectric porcelain compositions made of oxides of Bi, Ca, Mg, Nb at specific ratios and multiple internal conductors in turn, and providing input/output electrodes on this laminated body. CONSTITUTION:This dielectric porcelain composition is expressed by the formula xBiO3/2-y(Ca1-wMgw)O-zNbO5/2, where 0.44<=x<=0.55, 0.16<=y<=0.24, 0.29<=z<=0.36, 0<=w<=1.0, and x+y+z=1.0. Multiple sheet dielectric substances made of this dielectric porcelain composition and multiple internal conductors are overlapped in turn to form a laminated body constituted of dielectric layers 1 and internal conductor layers 2, 3, 4, and input/output electrodes 5 are provided on this laminated body. A laminated dielectric part is obtained which has the relative dielectric constant of about 50 or above, the no-load Q value of about 300 or above, and the absolute value of the temperature coefficient of the resonance frequency of about 100ppm/ deg.C or below and can be baked at about 1050 deg.C or below.

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 used in a high frequency region such as a microwave and a millimeter wave, and a laminated dielectric component using the same.

[0002]

2. Description of the Related Art In recent years, along with the increase in communication using electromagnetic waves in the microwave region such as car phones, mobile phones, satellite broadcasting, etc., miniaturization of dielectric parts such as filter elements and resonators that compose the equipment Is required.

In order to miniaturize such a dielectric component, the relative permittivity is high and the loss is low in the microwave region, that is, the no-load Q value is high and the temperature change of the resonance frequency is small. That is, it is important that the change in dielectric constant with temperature is small.

On the other hand, attempts have been made to miniaturize and enhance the functions of parts such as resonators by forming a laminated structure of a sheet-shaped dielectric material composed of a conductor and a dielectric ceramic composition. However, when used in a high frequency region such as microwave, a conductor having high conductivity is required, and Cu, Au,
It is necessary to use Ag or alloys thereof. Moreover, in the case of forming a laminated structure, it is necessary to fire the dielectric material and the conductor metal at the same time, so that the conductor metal is not melted and is not oxidized, that is, the firing is performed densely at a low temperature of 1050 ° C. or less. A dielectric porcelain composition to be bound is required. Furthermore, when Cu is used for the electrode, it is also necessary to sinter densely with a low oxygen partial pressure.

As a material having a high unloaded Q value, BaO--
The TiO ₂ —Sm ₂ O ₃ system is disclosed in JP-A-57-15309. This material has a relative dielectric constant of about 80,
High unloaded Q of about 2000 to 3000 at 2 to 4 GHz
And a temperature coefficient of the resonance frequency of about −400 to 400 ppm / ° C. Further, as a material that can be fired at a low temperature, Bi ₂ O ₃ —ZnO—Nb ₂ O ₅ system is disclosed in JP-A-4-28.
It is disclosed in Japanese Patent No. 5046. This material is 850
Sintered at 1000 ℃, relative dielectric constant of 80 or more, 2-4G
It has an unloaded Q value of 100 or more at Hz and a temperature coefficient of resonance frequency of -150 ppm / ° C or more.

[0006]

Among the above conventional materials [0005], the BaO-TiO ₂ -Sm ₂ O ₃ based material firing temperature 1
Since it is as high as about 300 ° C., there is a problem that it cannot be co-fired with the high conductivity electrode. In addition, Bi ₂ O ₃ -Zn
The O—Nb ₂ O ₅ based material has a problem that the unloaded Q value is low.

The present invention solves such problems and provides a dielectric ceramic composition having a high relative permittivity and a high unloaded Q value, a low temperature coefficient of resonance frequency, and a low temperature sintering property. The purpose is to do.

[0008]

In order to achieve this object, the dielectric ceramic composition of the present invention is represented by (Chemical Formula 3).

[0009]

[Chemical 3]

[0010]

With the above structure, the relative permittivity is 50 or more, the unloaded Q value is 300 or more, and the absolute value of the temperature coefficient of the resonance frequency is 100 ppm / ° C. or less, and further firing can be performed at 1050 ° C. or less.

[0011]

【Example】

(Embodiment 1) Hereinafter, the first embodiment of the present invention will be described in detail.

High purity Bi ₂ O ₃ and CaC as starting materials
O ₃ , Nb ₂ O ₃ and MgCO ₃ were used and weighed so as to have the composition shown in (Table 1). These powders were placed in a polyethylene ball mill, stabilized zirconia boulders and pure water were added, and wet-mixed for 5 to 20 hours. The obtained mixed powder was put in an alumina container and calcined at 700 to 850 ° C. for 1 to 3 hours. Put the calcined powder in the ball mill,
Stabilized zirconia boulders and pure water were added and wet-milled for 5 to 20 hours to obtain a raw material powder. To this raw material powder, a 5% aqueous solution of polyvinyl alcohol is added as a binder.
After adding 10 wt% to granulate and sieving through a 30-mesh sieve, the diameter is 13 mm and the thickness is 5 to 7 at 100 MPa.
It was molded into a cylindrical shape of mm. The obtained molded body was placed in a magnesia container, heated at 600 to 650 ° C. for 1 to 3 hours to incinerate the binder, and then fired at 850 to 1050 ° C. for 1 to 4 hours to obtain a sintered body. Of the obtained sintered bodies, both surfaces of the sintered body that was fired at a temperature at which the density was the highest were polished, and the dielectric characteristics with microwaves were measured. The measurement was performed by a dielectric resonance method, and a relative permittivity (hereinafter referred to as ε _r ), a no-load Q value (hereinafter referred to as Q value), and a temperature coefficient of resonance frequency (hereinafter referred to as τ _f ) were calculated. In the measurement of ε _r and Q value, the resonance frequency was 3 to 5 GHz. τ _f is -25
It was measured in the range of 85 ° C. Five measurement samples were prepared and the characteristics were evaluated.

The average values of the results are shown in (Table 1).

[0014]

[Table 1]

In Table 1, those marked with * are comparative examples outside the claims of the present invention. BiO _3/2 (x)
Is greater than 0.55, or Ca _1-w Mg
_w (y) is greater than 0.24, or NbO _5/2
When (z) is larger than 0.36, the Q value is lower than 300. Further, either BiO _3/2 (x) is less than 0.44, or Ca _1-w Mg or _w (y) is less than 0.16, or more NbO _5/2 (z) is 0.29 When it becomes smaller, the Q value also becomes lower than 300. The reason for such a decrease in the unloaded Q value is considered to be that many other phases having a low unloaded Q value are generated outside the limited composition range. Further, by substituting a part of Ca with Sr, the firing temperature can be further lowered. Sr is the same alkaline earth metal as Ca and has similar ionic properties, and even if it is replaced, Sr does not significantly affect the dielectric properties. However, SrO has a lower melting point than CaO, and is considered to have the effect of lowering the sintering temperature of the entire composition system. For this reason, the scope of the present invention is limited.

As is clear from the above, the dielectric ceramic composition according to the present embodiment is densely sintered at a low temperature of 1050 ° C. or less within the composition range included in the claims, and
Above ε _r , Q value above 300 and absolute value is 100 ppm /
Excellent characteristics are obtained in terms of τ _f below ℃. Also,
Since Cu was used as an electrode, even if it was fired in nitrogen, almost no change was observed in firing temperature and characteristics.

(Second Embodiment) The second embodiment of the present invention will be described in detail below.

High-purity Bi ₂ O ₃ , CaC as a starting material
Using O ₃ , Nb ₂ O ₃ , MgCO ₃ and CuO, (Table 2)
The composition was weighed so as to obtain the composition shown in. The method for producing the sintered body and the method for evaluating the characteristics were the same as in Example 1. The results are shown in (Table 2).

[0019]

[Table 2]

In Table 2, those marked with * are comparative examples outside the claims of the present invention. As is clear from this (Table 2), the dielectric ceramic composition according to the present example is
By adding the Cu component, an excellent effect can be obtained in that the firing temperature is lowered without largely deteriorating the microwave characteristics of the dielectric ceramic. It is considered that this is because Cu easily forms a low melting point compound with Bi or the like, so that firing can be performed at a lower temperature. However, since the Q value gradually decreases with the addition of the Cu component, Cu /
In the composition range of (Bi + Ca + Mg + Nb)> 0.04, the Q value is less than 300. For this reason, the scope of the present invention is limited.

As is clear from the above, the dielectric ceramic composition according to the present embodiment is densely sintered at a low temperature of 1050 ° C. or lower within the composition range included in the claims, and
Above ε _r , Q value above 300 and absolute value is 100 ppm /
Excellent characteristics can be obtained in terms of τ _{f of not} higher than ° C, and the firing temperature can be further lowered by adding a small amount of Cu. Further, as in Example 1, even when firing in nitrogen, there was almost no change in firing temperature and characteristics.

(Embodiment 3) A third embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a front sectional view of the laminated dielectric resonator of this embodiment, FIG. 2 is a side sectional view of the laminated dielectric resonator of this embodiment, and FIG. 3 is a laminated dielectric of this embodiment. It is a perspective view of a resonator.

In the figure, 1 is a dielectric layer, 2, 3 and 4 are internal conductor layers, and 5 is an external electrode. High-purity B as a starting material
i ₂ O ₃ , CaCO ₃ , Nb ₂ O ₃ , MgCO ₃ and CuO were used and weighed so as to have the composition shown in Sample No. 26 in (Table 2). The raw material powder was produced in the same manner as in Example 1. An organic binder, a solvent and a plasticizer were added to and mixed with the obtained raw material powder, and a dielectric sheet was formed by a doctor blade method. As the conductor electrode, the metal shown in (Table 3) was selected and kneaded with the vehicle to form a paste. However, when Cu is used as the conductor electrode, C
uO paste was used.

[0025]

[Table 3]

FIG. 4 is an exploded view of the laminated dielectric component in this embodiment. First, the inner conductor layer 2 was screen-printed on the dielectric layer 1 composed of a plurality of molded dielectric sheets. The dielectric layer 1 was provided thereon, and the internal conductor layer 3 was screen-printed on the dielectric layer 1. The length of the inner conductor layer 3 to be the strip line was 13 mm. Further, the dielectric layer 1 was provided thereon, and the inner conductor layer 4 was screen-printed. Finally, the dielectric layer 1 is provided and pressed by hot pressing,
The binder was incinerated by heat treatment in air. Then Cu
When the O paste is used, it is heat treated in hydrogen to reduce it to the conductor electrode Cu, then in nitrogen so as not to oxidize the conductor electrode, and in the case of other conductor electrodes, in air, respectively.
It was baked at 00 ° C. Finally, a Cu electrode as the external electrode 5 was baked in a nitrogen atmosphere to obtain a laminated dielectric resonator. The length of the internal conductor layer 3 to be the strip line after firing was 11.4 to 11.5 mm. Ten measurement samples were prepared and the characteristics were evaluated. The average value of the results (Table 3)
Shown in.

As is clear from this (Table 3), the laminated dielectric resonators according to this example are excellent in that the resonance frequencies are all around 850 MHz and the Q value is 100 or more.

The relative dielectric constant of the dielectric ceramic composition constituting this laminated dielectric resonator is as high as about 60.

However, since the relative dielectric constant of the conventional low temperature firing substrate material is about 8, a strip line length of 31.5 mm is required to obtain the same resonance frequency with the same structure as the resonator of this embodiment. Was needed. Thus, the stripline length of the resonator of this embodiment is as short as 11.5 mm,
A very small resonator was obtained at MHZ.

It is also possible to obtain a smaller resonator by forming the strip line into a curved shape or a laminated shape. It is also possible to configure a bandpass filter or the like by combining these with a capacitor.

[0031]

As described above, by using the dielectric ceramic composition of the present invention represented by (Chemical formula 1), both the relative dielectric constant and the unloaded Q value are high, and the temperature coefficient of the resonance frequency is high. The size is small, and low temperature firing is possible.

Since the laminated type dielectric part using this dielectric ceramic composition is a conductor having a high dielectric constant, it can be sufficiently used even in a high frequency region such as microwaves. Furthermore, since a compact resonator system can be constructed, it greatly contributes to the miniaturization of communication devices such as car phones and mobile phones that use electromagnetic waves in the microwave range.

[Brief description of drawings]

FIG. 1 is a front sectional view of a laminated dielectric resonator according to an embodiment of the present invention.

FIG. 2 is a side sectional view of a laminated dielectric resonator according to an embodiment of the present invention.

FIG. 3 is a perspective view of a laminated dielectric resonator according to an embodiment of the present invention.

FIG. 4 is an exploded view of a laminated dielectric resonator according to an embodiment of the present invention.

[Explanation of symbols]

 1 Dielectric Layer 2 Inner Conductor Layer 3 Inner Conductor Layer 4 Inner Conductor Layer 5 External Electrode

Claims (4)

[Claims] 1. A dielectric ceramic composition represented by the chemical formula 1. [Chemical 1] 2. Cu / (Bi + Ca + Mg + Nb) ≦
The dielectric ceramic composition according to claim 1, wherein Cu is added so as to have a composition of 0.04. 3. A laminated body in which a plurality of sheet-shaped dielectrics and a plurality of internal conductors are alternately stacked, and input / output electrodes provided in the laminated body, wherein the dielectric is represented by the following chemical formula. Laminated dielectric part made of the above-mentioned dielectric ceramic composition. [Chemical 2] 4. The dielectric is Cu / (Bi + Ca + Mg +)
Nb) containing Cu having a composition of 0.04.
The laminated dielectric component described.