JPH0717444B2 - Dielectric porcelain composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a high frequency dielectric ceramic composition that constitutes a resonator or the like used mainly in a region called a microwave band.

2. Description of the Related Art In recent years, antenna duplexers (duplexers) used for wireless telephones such as car phones, mobile phones, cordless phones, etc.
Resonator used for power supply, voltage controlled oscillator, etc., or CATV
High-frequency dielectric porcelain is often used for filters and the like used for tuners. By using a high dielectric constant material in such a resonator, etc. By shortening the length of (εr: relative permittivity) and confining the microwave of 1 wavelength, 1/2 wavelength, or 1/4 wavelength at such frequency in the high frequency dielectric porcelain, the desired effect can be obtained. As described above, the one configured in a small size is generally known. The characteristics required for such a high frequency dielectric porcelain include: (1) the wavelength of the electromagnetic wave in the dielectric (However, εr is shortened to the relative permittivity), and if the resonance frequency is the same, the smaller the permittivity, the smaller the size. Therefore, the permittivity is as large as possible. (3) The change rate of the resonance frequency with respect to temperature change is small, that is, the temperature dependence of the dielectric constant is small and stable, and the following three characteristics can be mentioned.

Also, in the microwave band, when applied in the region of about 1 GHz, which is a relatively low frequency band used for car phones, personal radios, cordless telephones, etc., the wavelength becomes considerably long, so the resonator etc. should be miniaturized. Therefore, the dielectric ceramic composition needs to have a considerably high dielectric constant.

Conventionally, as a dielectric ceramic composition of this kind, for example, Ba
_{O-Nd 2 O 3 -TiO 2} -Bi 2 O 3 based compositions, such as _{BaO-Nd 2 O 3 -TiO 2} -PbO -based compositions are known.

However, even in these materials, the dielectric constant is εr =
It is about 70 to 90, and if we try to obtain a dielectric constant higher than that, temperature characteristics will deteriorate rapidly, such as the Q value, and the dielectric constant will be increased to reduce the size of the resonator. There was a limit.

In addition, the internal electrode paste is printed on the dielectric green sheet to stack them, and then the internal electrode paste and the dielectric green sheet are co-sintered, and external electrodes are formed on this sintered body, a so-called laminated type. Dielectric resonator,
It is also considered that the shape of the inner conductor is designed in various shapes by using a filter, and the size of the sintered body is made significantly smaller than the resonance wavelength.

However, since electrodes used in the microwave band are required to have low resistance, metals such as Au, Ag, Cu, and Al are generally used as electrodes in resonators in this band, and co-firing The composition requires a composition that sinters at a temperature below the melting point of those metals.

However, the conventional high frequency dielectric porcelain is 1300 to 1500
Au which is sintered at ℃ and suitable for microwave band,
There is a problem that metallic materials such as Ag and Cu cannot be adopted as internal electrode materials.

The present invention has been invented in view of the above problems,
Higher permittivity, lower dielectric loss, smaller temperature dependence of the permittivity and stable, which enables further miniaturization of high frequency resonators, etc. Has little temperature dependence and is sintered at low temperature
It is an object of the present invention to provide a dielectric ceramic composition that can be sintered at low temperature and can use Au, Ag-Pd, etc. as internal electrode materials.

Means for Solving the Problems As a result of repeated research to achieve the above object, the present inventor
Si is added to the system consisting of O, Nd ₂ O ₃ , Sm ₂ O ₃ , TiO ₂ , PbO and Bi ₂ O _3.
By adding O ₂ , ZnO, and B ₂ O ₃ , it has a high dielectric constant, low temperature dependence of the dielectric constant, temperature dependence of the resonance frequency in the resonator, and high Q value. Moreover, Au and Ag-Pd can be used as internal electrodes.
The inventors have found that a dielectric ceramic composition that can be sintered at a low temperature of ℃ can be obtained, and completed the present invention.

That is, the dielectric porcelain composition according to the present invention has a composition formula of xBaO ・ yNd ₂ O ₃・ zSm ₂ O ₃・ uTiO ₂・ vPbO ・ wBi ₂ O ₃ where 0.080 <x <0.160 0.121 <y <0.130 0.005 <Z <0.030 0.650 <u <0.700 0.045 <v <0.010 0.005 <w <0.045 x + y + z + u + v + w = 1 As a subcomponent, SiO ₂ is 1.2 to 4.0% by weight ZnO is 0.2 to 3.5% by weight and B is _The feature is that ₂ O ₃ is added in a proportion of 0.1 to 2.5% by weight.

The dielectric porcelain composition according to the present invention has REO as a main component.
(Rare earth oxide) -BaO-TiO ₂ system is basically used, and Nd ₂ O ₃ and Sm ₂ O ₃ are used as rare earth oxide, and PbO
And Bi ₂ O ₃ are added. And 1000 ℃ ~ 1050 ℃
For enabling low-temperature sintering, as a secondary component, SiO _2, Zn
O and B ₂ O ₃ are added.

If each component deviates from the above range, it becomes impossible to sinter at a low temperature of 1000 ° C to 1050 ° C, or even if possible, the dielectric constant εr is low, or the temperature coefficient of the resonance frequency is ± 20ppm. Out of the range of / ℃, or Q value is 15
It becomes as low as 00 or less.

Examples and Comparative Examples (I) Preparation of Dielectric Porcelain High-purity barium carbonate (BaCO ₃ ), neodymium oxide (N
d ₂ O ₃ ), samarium oxide (Sm ₂ O ₃ ), titanium oxide (Ti
O ₂ ), lead oxide (PbO), bismuth oxide (Bi ₂ O ₃ ), silicon dioxide (SiO ₂ ), zinc oxide (ZnO), boric anhydride (B ₂ O ₃ ).
Were weighed at the ratios shown in Table 1.

The above starting materials were wet mixed for one day in a ball mill and then dried.

The above mixture was calcined at a temperature of about 900 ° C. for about 2 hours.

The calcined mixture was wet-ground for one day in a ball mill and then dried.

About 1% by weight of a binder was added to the above dry powder to adjust the size.

It was molded at a pressure of about 1000 kg / cm ² and fired in the air at 1000 to 1350 ° C. for about 2 hours.

(II) Measurement of characteristics The obtained dielectric porcelain was measured for dielectric constant, Q value and temperature coefficient of resonance frequency at a resonance frequency of 3.0 to 4.0 GHz by a dielectric cylinder resonator.

The results are shown in Table 1.

The problems in the comparative example outside the composition range according to the present invention will be described below by comparing the example and the comparative example.

When x> 0.160: As in No. 5, a sintering temperature of 1100 ° C. or higher is required and the object of the present invention cannot be achieved.

When x <0.080: Q value becomes low as No.12.

When y> 0.130: As in No. 6, a sintering temperature of 1100 ° C or higher is required.

When y <0.121: As in No. 7, the sintering temperature must be 1100 ° C or higher.

When z> 0.030: As in No. 9, τf becomes large on the negative side.

When z <0.005: τf becomes large on the positive side like No.8.

When u> 0.700: As in No. 7, the sintering temperature becomes 1100 ° C or higher.

When u <0.650: Q value becomes low as No.5.

When v> 0.100: The Q value decreases as in No.12.

When v <0.045: The Q value becomes low like No.13.

When w> 0.045: Q value becomes low as No.13.

When w <0.005: τf becomes large on the positive side as in No.15.

When SiO ₂ > 4.0% by weight: εr becomes small as in No. 3.

When SiO ₂ <1.2% by weight: The sintering temperature becomes 1100 ° C or higher as in No. 2, No. 18, and No. 21.

When ZnO> 3.5% by weight: Q value is low as in No. 24.

When ZnO <0.2% by weight: The sintering temperature becomes 1100 ° C or higher as in No. 19.

When B ₂ O ₃ > 2.5% by weight: Q value becomes low like No.26.

When B ₂ O ₃ <0.1 wt%: Sintering temperature is 1100 ° C as No.16
That's all.

As described above, the above-mentioned problems remain in the comparative example.

On the other hand, NO.1, which is within the range of the composition according to the present invention,
For 4, 10, 11, 14, 17, 20, 22, 23, and 25, the dielectric constants are all high with εr = 65.3 to 78.2, and the Q value is f × Q =
It is as high as 1537 to 2650, and the temperature coefficient of resonance frequency is τf.
= Stable at -10.8 to +9.1 ppm / ° C, and 1000 to 1050 ° C
And the object of the present invention is achieved.

Effects of the Invention As is apparent from the above description, in the dielectric ceramic composition according to the present invention, BaO, Nd ₂ O ₃ , Sm ₂ O ₃ , TiO ₂ , Pb
O, Bi ₂ O ₃ as main components, and SiO ₂ , ZnO, B ₂ O ₃ as secondary components
Is added in a specified amount, the dielectric constant and Q value are high, and the temperature dependence of the resonance frequency is small. Furthermore, Au, Ag-P
It is possible to obtain a dielectric ceramic composition which can be used as an internal electrode and which can be sintered at a low temperature.

Therefore, the size of the high-frequency resonator, the filter, etc. can be greatly reduced, and its usefulness is extremely large.

Claims (1)

[Claims] 1. A composition formula is xBaO.yNd ₂ O ₃ .zSm ₂ O ₃ .uTiO ₂ .vPbO.wBi ₂ O ₃ where 0.080 <x <0.160 0.121 <y <0.130 0.005 <z <0.030 0.650 <u < 0.700 0.045 <v <0.010 0.005 <w <0.045 x + y + z + u + v + w = 1 to the main component, SiO ₂ is 1.2 to 4.0 wt% ZnO is 0.2 to 3.5 wt% and B ₂ O ₃ is 0.1 to 2.5 wt% as a sub-component. % Of the dielectric ceramic composition.