JPH11322425A - Dielectric porcelain composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dielectric porcelain composition having a high relative dielectric constant εr , in which a temperature factor τf of a resonance frequency is as close to zero as possible and having great Q×f value, and furthermore which can be simultaneously sintered even if low melting temperature Au, Ag, Cu and their alloy or the like are used for an inner electrode material. SOLUTION: The objective composition is expressed by the formula aBiO3/2 -b(Sr1-x-y Mgx Bay )O-cNbO5/2 (wherein unit of (a), (b) and (c) is mol.%) and is in a range of 41.0<=a<=51.0, 17.0<=b<=25.0, 29.0<=c<=39.0 (a+b+c=100 mol.%), 0<=x<=0.4 and 0<=y<=0.4. At least one oxide selected from B2 O3 , SiO2 , GeO2 and SnO2 is preferably added <=2.0 pts.wt. to the dielectric porcelain component.

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 mainly used for communication and broadcasting equipment for a microwave band.

[0002]

2. Description of the Related Art In recent years, with the progress of communication technology, mobile communication systems such as car phones, mobile phones, and PHS,
S (Global Positioning System) is rapidly spreading. For this reason, the frequency band used for communication has been expanded, and the use in the microwave band has become active. Traditionally, circuits used in this microwave band include cavity resonators,
Antennas and the like were used. However, these parts
Since the size is about the same as the wavelength of microwaves, it has not been possible to reduce the size of components that can be applied to automobile telephones, mobile telephones, small GPS devices, and the like.

On the other hand, in recent years, the use of dielectric resonators in microwave filters and frequency stabilizing circuits of oscillators has made vigorous miniaturization of circuit components and is becoming popular. Required characteristics of the dielectric material used in such a dielectric resonator, relative dielectric constant epsilon _r in the use frequency band is large, the temperature coefficient tau _f of resonance frequency is as close as possible to zero, in the microwave band Dielectric loss tan
δ (= 1 / Q) is small. Incidentally, the magnitude of the dielectric loss tan δ in the microwave band is generally Q ×
It is expressed in the form of f (f is the resonance frequency at that time). Therefore, the expression of Q × f is used below.

Hitherto, Ba (Zn) has been used as a dielectric ceramic composition for a microwave or temperature compensating capacitor.
_1/3 Ta _2/3 ) O ₃ system, BaO-TiO ₂ system, ZrO ₂
—SnO ₂ —TiO ₂ , BaO—Noble oxide—Ti
Materials such as O ₂ -based and (Pb, Ca) ZrO ₃ are known.

However, the material of the composition has been previously disclosed, in the microwave band, the relative permittivity ε as _r greater Q × f there was a tendency that small. In order to solve the drawback, the present inventors set the relative permittivity ε _r to 110
Above, as a composition having a small absolute value | τ _f | of the temperature coefficient of the resonance frequency and a sufficiently large Q × f, BaO-La ₂ O
The _{3 -Sm 2 O 3 -Bi 2 O} 3 -TiO 2, proposed (Japanese Patent Laid-Open 7-172912, JP-reference).

In order to further reduce the size, function and cost of a microwave circuit, it is effective to use a laminated structure of a conductor and a dielectric ceramic, which has already been put to practical use. It can be realized by applying a ceramic lamination technology.

However, conductors of elements used in the microwave band generally include Au, Ag, Cu,
Alternatively, their alloys and the like are used, and in order to obtain the above-described laminated device, it is necessary that a conductor metal having a relatively low melting point and a dielectric material can be simultaneously sintered. For this purpose, various low-temperature fired ceramics have been proposed.

For example, in Japanese Patent Application Laid-Open No. 5-97508, Ba
0-Ti0 ₂ -R ₂ O ₃ in _{-PbO-Bi 2 O 3 B 2} O
A low-temperature fired material to which ₃ , SiO ₂ and ZnO are added has been proposed. Also, Japanese Patent Application Laid-Open No. Hei 5-234420 discloses that Ba
O-TiO ₂ -Nd ₂ O ₃ in the Bi ₂ O _3, MnO, Pb
Low-temperature firing materials to which O, ZnO, and Al ₂ O ₃ are added have been proposed. Also, JP-A-3-290358-2903
59 No., in _{JP-A-3-295854~295856, BaO-Nd 2 O 3} -Sm 2 O 3 -TiO 2 -Bi
GeO _2, CuO in _{2 O 3 -PbO, B 2 O} 3, SiO
₂ , low-temperature firing materials to which ZnO is added have been proposed.

[0009]

However, in the low-temperature sintering materials proposed by them, the relative dielectric constant ε _r is 70%.
Above, and the absolute value of the temperature coefficient of the resonance frequency | τ _f |
A material having a concentration of 0 ppm / ° C. or less cannot be obtained.

[0010] Therefore, the technical problem of the present invention, the dielectric constant epsilon _r is large, close to the temperature coefficient tau _f it is possible zero resonant frequency, Q × f value is large and a low melting point A
It is an object of the present invention to provide a dielectric ceramic composition which can be simultaneously sintered even when u, Ag, Cu, an alloy thereof, or the like is used as an internal electrode material.

[0011]

In order to solve the above-mentioned problems, the present inventors have proposed Bi ₂ O _3- (Sr, Mg, B
a) In an O—Nb ₂ O ₅ system or in the above-mentioned composition system, B ₂ O
₃ , SiO ₂ , GeO ₂ , and SnO ₂ are added to increase the relative dielectric constant ε _r , the temperature coefficient τ _f of the resonance frequency is close to zero, the Q × f value is large, and the Au and the melting point are low. A
It has been found that a dielectric porcelain material that can be simultaneously sintered even when g, Cu, their alloys, etc. are used as the internal electrode material can be obtained.

That is, according to the present invention, the general formula is aBi
_{O 3/2 -b (Sr 1-xy} Mg x Ba y) O-cNbO
_5/2 (where the units of a, b and c are mol%)
1.0 ≦ a ≦ 51.0, 17.0 ≦ b ≦ 25.0, 2
9.0 ≦ c ≦ 39.0 (a + b + c = 100 mol%),
A dielectric porcelain composition characterized by being in the range of 0 ≦ x ≦ 0.4 and 0 ≦ y ≦ 0.4 is obtained.

Further, according to the present invention, B ₂ O ₃ , SiO ₂ , GeO ₂ , SnO is used for the dielectric ceramic composition.
_2. A dielectric porcelain composition characterized by adding at least 2.0 parts by weight of at least one oxide selected from ₂ ).

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows BiO _3/2 , (Sr, Mg, Ba) O and Nb, which are the main components of the dielectric ceramic composition of the present invention.
It is a figure which shows the range of O5 _{/ 2} . As shown in FIG. 1, the main component of the dielectric porcelain composition of the present invention has a general formula of aBiO
_{3/2 -b (Sr 1-xy Mg} x Ba y) O-cNbO 5/2
(However, the units of a, b, and c are mol%).
0 ≦ a ≦ 51.0, 17.0 ≦ b ≦ 25.0, 29.0
≦ c ≦ 39.0 (a + b + c = 100 mol%), 0 ≦ x
≦ 0.4, 0 ≦ y ≦ 0.4, and the range is a region including the boundary line indicated by oblique line 1.

As described above, according to the present invention, Bi ₂ O
_{In the 3-} (Sr, Mg, Ba) O-Nb ₂ O, system, the relative permittivity ε _r is large, the temperature coefficient τ _f of the resonance frequency is close to zero, the Q × f value is large, and the melting point Low Au, A
It is possible to obtain a dielectric ceramic material that can be simultaneously sintered even when g, Cu, an alloy thereof, or the like is used as an internal electrode material.

Further, the dielectric porcelain composition of the present invention is characterized in that B ₂ O ₃ , SiO ₂ , GeO ₂ , Sn
At least one oxide selected from O ₂
Not more than parts by weight are added.

In the present invention, by adding B ₂ O ₃ , SiO ₂ , GeO ₂ , and SnO ₂ to the composition system of the main component, deterioration of the dielectric characteristics is reduced and sintering can be performed at a lower temperature. A dielectric porcelain material is obtained.

Now, an embodiment of the dielectric magnetic composition of the present invention will be described.

(First Embodiment) First, Bi ₂ O ₃ ,
After weighing each powder of SrO, MgO, BaCO ₃ , and Nb ₂ O ₅ according to each composition, the mixture was wet-mixed with pure water using a zirconia ball in a resin ball mill for 20 hours to obtain a mixture. Next, after drying this mixed product, it was calcined in the air at a temperature of 750 to 850 ° C. for about 4 hours to obtain a calcined product. Further, the average crushed particle size of the above ball mill is 0.
After wet pulverization to 8 μm or less, drying and granulation were performed. This was shaped into a disk having a diameter of 15 mm and a thickness of about 6 mm, and sintered at a temperature of 850 to 1200 ° C. for about 2 hours to obtain a dielectric ceramic having a composition shown in Table 1 below.
In Table 1 below, the composition is aBiO _3/2 -b (Sr _{1-xy
Mg x Ba y) O-cNbO} 5/2 (a + b + c = 100
Mol%).

Next, for the dielectric ceramics of each composition, the relative permittivity εr, Q × f value, and the temperature coefficient τ _f of the resonance frequency were measured by the dielectric resonator method. The temperature coefficient τ _f of the resonance frequency was determined from the difference between the resonance frequencies f in the temperature range of + 20 ° C. to + 60 ° C. by the following equation (1).

[0022]

(Equation 1)

The measurement results are shown in Table 1 below. In addition, the resonance frequency was 2-3 GHz.

[0024]

[Table 1]

As is apparent from Table 1 above, aBiO
_{3/2 -b (Sr 1-xy Mg} x Ba y) O-cNbO 5/2
(However, the units of a, b, and c are mol%).
0 ≦ a ≦ 51.0, 17.0 ≦ b ≦ 25.0, 29.0
If ≦ c ≦ 39.0, 0 ≦ x ≦ 0.4 and 0 ≦ y ≦ 0.4, the relative dielectric constant ε _r is as large as 70 or more, the temperature coefficient τ _f of the resonance frequency is close to zero, and Q × f value is large, and
A dielectric ceramic material that can be sintered at a low temperature of 1100 ° C. or less is obtained. Further, the Sr site Mg, Yotsute to be replaced by Ba, the dielectric ceramic material is obtained having a larger relative dielectric constant epsilon _r.

On the other hand, in comparative examples other than the present invention,
If the content of BiO _3/2 is less than 41.0 mol%,
The following low-temperature sintering becomes impossible. In addition, BiO _3/2 is 5
If it is more than 1.0 mol% or NbO _5/2 is less than 29.0 mol%, a large ε _r cannot be obtained. Also,
(Sr, Mg, Ba) O is less than 17.0 mol%,
Or more than 25.0 mol%, or NbO _5/2 is 3
If it is more than 9.0 mol%, the Q × f value deteriorates. Also,
When the Mg substitution amount x of the Sr site exceeds 0.4 or the Ba substitution amount y exceeds 0.4, the Q × f value deteriorates.

(Second Embodiment) Bi ₂ O ₃ , Sr
Each powder of O, MgO, BaCO ₃ , and Nb ₂ O ₅ was weighed according to each composition, and a calcined product was obtained by the same method as that shown in the first embodiment. Next, B ₂ O ₃ , SiO ₂ , G
The powders of eO ₂ and SnO ₂ were respectively weighed so as to have the ratios shown in Table 2 below, added to the calcined product, and averagely ground to a particle size of 0.8 μm in the same ball mill as shown in the first embodiment.
After wet pulverization (also serving as mixing) as described below, it was molded and sintered at a temperature of 800 to 1000 ° C. to obtain a dielectric ceramic having a composition shown in Table 2 below. In Table 2, the composition is aB
_{iO 3/2 -b (Sr 1-xy} Mg x Ba y) O-cNbO
_5/2 (a + b + c = 100 mol%).

Next, the dielectric porcelain of each composition is described in the first section.
When the same measurement as that described in the embodiment was performed, the measurement results shown in Table 2 below were obtained.

[0029]

[Table 2]

As apparent from Table 2 above, BiO _3/2
- (Sr, Mg, Ba) to _{O-NbO 5/2, B 2 O} 3,
If at least 2.0 parts by weight of one or more oxides selected from SiO ₂ , GeO ₂ , and SnO ₂ are added, dielectric properties are hardly deteriorated, and the sintering temperature can be further lowered. However, addition exceeding 2.0 parts by weight results in deterioration of the dielectric properties.

[0031]

As described above, according to the present invention,
Au having a large relative dielectric constant ε _r , a temperature coefficient τ _f of the resonance frequency close to zero, a large Q × f value, and a low melting point.
A dielectric porcelain composition that can be co-sintered even when Ag, Cu, or an alloy thereof is used for the internal electrode material is obtained.

[Brief description of the drawings]

FIG. 1 shows Bi which is a main component of the dielectric ceramic composition of the present invention.
It is a figure which shows the range of O3 _{/ 2} , (Sr, Mg, Ba) O, and NbO5 _{/ 2} with a diagonal line.

[Explanation of symbols]

1 Shaded area showing the main component of the dielectric ceramic composition of the present invention

Claims (2)

[Claims] 1. The general formula is aBiO _3/2 -b (Sr
_{1-xy Mg x Ba y)} O-cNbO 5/2 ( provided that, a,
The units of b and c are mol%) and 41.0 ≦ a ≦ 51.
0, 17.0 ≦ b ≦ 25.0, 29.0 ≦ c ≦ 39.0
(A + b + c = 100 mol%), 0 ≦ x ≦ 0.4, 0 ≦
A dielectric ceramic composition, wherein y is in the range of 0.4. 2. The dielectric ceramic composition according to claim 1, wherein at least one kind of oxide selected from B ₂ O ₃ , SiO ₂ , GeO ₂ and SnO ₂ is 2.0 parts by weight. A dielectric porcelain composition comprising: