JPH0825794B2 - Dielectric porcelain composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a dielectric porcelain composition, and more particularly to a dielectric porcelain composition suitable as a resonator in the microwave region and a circuit board material.

(Prior art) In recent years, with the practical use of car telephones, cordless telephones, personal radios, and satellite broadcasting receivers, microwave circuits have been developed into ICs, the range of use of gun oscillators has been expanded, and gallium arsenide field effect transistors have been developed. Dielectric porcelain is widely used in the microwave region such as the application of (GaAs FET) to an oscillator.

Such high-frequency dielectric porcelain is mainly used for resonators. The characteristics required therefor are (1) the wavelength of electromagnetic waves in the dielectric. (However, εr is the 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. (2) The permittivity loss at high frequencies is small. (3) There is little change in the resonance frequency with respect to temperature, that is, the temperature dependence of the dielectric constant is small and stable, and the above three characteristics are mentioned. In the microwave region as well, if it is about 1 GHz, which is a relatively low frequency band used for car phones, personal radios, cordless telephones, etc., the wavelength will be considerably large when applied to this, so it is necessary to reduce the size. It needs to have a fairly high dielectric constant.

Conventionally, as this type of dielectric ceramic, for example, BaO-T
Known are iO ₂ -based materials, BaO-REO-TiO ₂ (where REO is an oxide of a rare earth element, the same applies hereinafter) -based materials, and (BaSrCa) (ZrTi) O ₃ -based materials.

(Problems to be Solved by the Invention) However, BaO-TiO ₂ based materials and (BaSrCa) (ZrT
i) O ₃ -based materials have a very low dielectric loss in the high frequency band of 4 to 10 GHz, but have a low dielectric constant of 29 to 40, and are practically used for miniaturization especially in the frequency band of about 1 GHz. The problem arises. Further, if the dielectric constant is increased, the temperature characteristic of the resonance frequency or the dielectric loss tends to be extremely deteriorated.

In addition, regarding BaO-REO-TiO ₂ materials, a systematic experiment report [RL Bolton, “Temperature Compensating Cera
mic Capacitors in the System Baria−Rare Earth Oxi
de－Titania "PhD Thesis, University of Illinois－Urb
ana, 1968. and D. Kolor et al., Ber Deutsch Keram. Ges.,
55.346-348 (1978)], but these are all 1 MH
It was measured at z and was not intended for application in the high frequency band around 1 GHz. When it is used as a dielectric resonator, it has a large dielectric constant of 70 to 80 and a small dielectric loss, but the temperature coefficient of the dielectric constant is N100 to N150ppm / ° C (however, N
Is very large on the N side, and the temperature coefficient τf of the resonance frequency becomes large on the P (positive) side. For example, when it is used for a bandpass filter of a personal wireless device, the transmission / reception band has a temperature difference. Due to the change, the frequency band is deviated from the designated frequency band, and the frequency band enters the adjacent frequency band, which causes difficulty in transmission and reception, which is a practical problem. Also, in order to correct τf to NPO (0 direction), even if the amount of Nd ₂ O ₃ is increased,
The fact is that the dielectric ceramic composition for high frequency, which has the above-mentioned three characteristics, has not yet been developed because the dielectric constant is lowered and the dielectric loss is increased.

(Object of the Invention) The present invention has been devised in view of the above-mentioned drawbacks, and has a high dielectric constant (70 or more) in order to enable downsizing of a resonator,
It is intended to provide a dielectric ceramic composition for high frequency, which has a dielectric loss as low as possible, a dielectric constant having a small temperature dependence and is stable, and a resonance frequency of a dielectric resonator having a small temperature dependence and being stable. .

(Means for Solving Problems) As a result of repeated research on the above problems, the present inventor found that Ba
It has a high dielectric constant by adding Mn to the system consisting of O, Nd ₂ O ₃ , TiO ₂ and Bi ₂ O ₃ and has a low temperature dependence of the dielectric constant and the resonance frequency of the resonator. It was found that a dielectric ceramic composition having a high Q value can be obtained, and the present invention was completed.

That is, according to the present invention, the composition formula is xBaO · yNd ₂ O ₃ · zTiO ₂ · wBi ₂ O ₃ where 0.110 ≦ x ≦ 0.170 0.120 ≦ y ≦ 0.185 0.630 ≦ z ≦ 0.710 0.020 ≦ w ≦ 0.090 x + y + z + w = 1 There is provided a dielectric ceramic composition containing Mn in the range of 0.003 to 0.3% by weight with respect to the main component represented by.

 Hereinafter, the present invention will be described in detail.

In order to modify the temperature characteristic of Nd ₂ O ₃ as REO in the BaO-REO-TiO ₂ system material, the present inventor first modified the temperature characteristic of the dielectric constant to the P side, that is, as a dielectric resonator. It has been proposed that, when used, the temperature coefficient τf of the resonance frequency is shifted to the N side) and Bi ₂ O ₃ is added to improve the temperature characteristics with a high dielectric constant. The present invention is based on this proposal. The Q value is significantly increased by adding manganese (Mn) to a dielectric mainly composed of BaO, TiO ₂ , Nd ₂ O ₃ , Bi ₂ O _3. The dielectric constant is further improved. Moreover, the range in which TiO ₂ is practically allowed can be expanded by adding Mn.

Therefore, the dielectric ceramic composition according to the present invention has a composition formula xBaO · yNd ₂ O ₃ · zTiO ₂ · wBi ₂ O ₃ in which 0.110 ≦ x ≦ 0.170 0.120 ≦ y ≦ 0.185 0.630 ≦ z ≦ 0.710 0.020 ≦ w ≦ 0.090 x + y + z + w = 0.003 to 0.3% by weight, preferably 0.001 to 0.2% by weight, based on the main component represented by = 1. The reason for limiting each component to the above numerical range is x> 0.17
When 0, the temperature coefficient τf of the resonance frequency becomes large on the P side and the Q value becomes small, and when x <0.110, the Q value becomes small. When y> 0.185, the dielectric constant becomes small, and when y <0.120, the Q value becomes small and τf becomes large on the P side. When z> 0.710, τf becomes large on the P side, and even when z <0.630, τf becomes large on the P side, and the dielectric constant also becomes small. When w> 0.090, the Q value and the dielectric constant are small, and when w <0.020, τf is large on the P side. On the other hand, when the amount of Mn is outside the above range, the Q value is small, and the effect of improving the Q value by adding Mn is not recognized.

Addition of Mn in the present invention is particularly preferably added as a compound, for example, MnCO ₃ , MnO, MnC ₂ O ₄ , MnCl ₂ , MnO ₂ ,
It is added in the form of Mn (NO ₃ ) ₂ and MnSO ₄ . When added as these compounds, the amount added may be such that the amount of Mn atoms falls within the range described above.

 Hereinafter, the present invention will be described with reference to the following examples.

〔Example〕

(I) Preparation of Dielectric Porcelain High-purity barium carbonate (BaCO ₃ ) and neodymium oxide (N
d ₂ O ₃ ), titanium oxide (TiO ₂ ) and bismuth oxide (Bi
₂ O ₃ ) and MnCO ₃ were weighed in the ratios of x, y, z, w and t shown in Table 1, respectively.

The above starting materials were wet mixed all day and night in a ball mill and dried.

The above mixture was calcined at 900 ° C. for 2 hours. By this calcination, Bi ₂ O ₃ is substantially in the form of BiTi _3/4 O ₃ and BaO-Nd ₂ O ₃ -TiO ₂
It has been added to the system.

The calcined mixture was wet pulverized for one day in a ball mill and dried.

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

It was molded at a pressure of about 800 kg / cm ² and fired at 1200 to 1450 ° C. for about 2 hours in the air.

(II) Measurement of characteristics The obtained dielectric porcelain was measured for dielectric constant, dielectric loss, and temperature coefficient of resonance frequency at a resonance frequency of 2.5 to 3.0 GHz by a dielectric cylinder resonator method (postresonator method).

 The results are shown in Table 1.

As is clear from Table 1, No. 5 and No. 6 or No. 7
As can be seen from the comparison with No.8, the temperature characteristics τf of the dielectric constant and resonance frequency hardly change, but Q due to the addition of Mn
It is understood that the values will be very high. Note that Mn is 0.3
If it exceeds 5% by weight, the effect of improving the Q value tends to be extremely reduced.

As shown in No. 13 to No. 20, when x, y, z, w in the main component composition deviates from the above range, the dielectric loss becomes large and the Q value decreases, or the dielectric constant decreases. Satisfactory results cannot be obtained because the rate decreases and τf increases.

In terms of characteristics, the dielectric material of the present invention has permittivity ε> 70, θ> 50
0, τf <30 was achieved.

〔The invention's effect〕

As described in detail above, according to the present invention, BaO, Nd ₂ O ₃ , Ti
By adding Mn in a predetermined amount to the composition containing O ₂ and Bi ₂ O ₃ as a main component, a Q value is improved, and a dielectric having a high dielectric constant and a small resonance frequency temperature dependence is obtained. As a result, the size of the resonator can be sufficiently miniaturized to about 1 GHz, and the allowable range can be expanded especially in the amount of TiO ₂ in the composition range of each component to be satisfied as compared with the case where Mn is not added. It is possible to eliminate the instability of the characteristics of the product as a result of the error at the time.

Claims (1)

[Claims] 1. The composition formula is represented by xBaO.yNd ₂ O ₃ .zTiO ₂ .wBi ₂ O ₃ formula: 0.110 ≦ x ≦ 0.170 0.120 ≦ y ≦ 0.185 0.630 ≦ z ≦ 0.710 0.020 ≦ w ≦ 0.090 x + y + z + w = 1 A dielectric ceramic composition containing Mn in an amount of 0.003 to 0.3% by weight based on the main component.