JP3474606B2 - Dielectric porcelain composition - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a dielectric ceramic composition used in the microwave region.

[0002]

2. Description of the Related Art In recent years, there has been a demand for downsizing of equipment with the progress of communication using electromagnetic waves in the microwave range, such as car telephones, portable telephones, and satellite broadcasting.
For this purpose, it is necessary to reduce the size of individual parts that make up the device. In these devices, the dielectric is incorporated into various filter elements, frequency stabilizing elements of oscillators, and the like. Since the size of these dielectric resonant devices is inversely proportional to the square root of the dielectric constant of the dielectric material used when using the same resonant mode, a high dielectric constant is required to fabricate a small resonant device. Materials are needed.
Another characteristic required for the dielectric is that it has a low loss in the microwave region, that is, a high no-load Q value.
Furthermore, the change in the resonance frequency with temperature is small, that is, the change in the dielectric constant with temperature is small. As a material having a large dielectric constant, BaO—TiO ₂ —Sm ₂ O ₃ system is disclosed in JP-A-57 / 57.
It is disclosed in Japanese Patent Publication No. 15309. This system has a relative dielectric constant of about 80, a high unloaded Q value of about 3000 at 2 to 4 GHz, and a temperature coefficient of a small resonance frequency.

On the other hand, the conductor and the dielectric porcelain have a laminated structure,
Attempts have been made to reduce the size and increase the functionality of resonant devices. When the conductor is used in a high frequency region such as microwave, it is necessary to have high conductivity, so Cu, A
It is necessary to use u, Ag, or alloys thereof. Further, when the dielectric ceramic has a laminated structure, it must be fired at the same time as the metal of the conductor, and therefore must be densely sintered under firing conditions in which the conductor metal does not melt and does not oxidize. That is, at a low temperature of 1050 ° C. or lower, and C
When u is used for the electrode, firing with a low oxygen partial pressure is required. As a dielectric porcelain satisfying such requirements, the present inventors have disclosed in Japanese Patent Application No. 4-27775, Bi ₂ O ₃
And filed what was contained Cu component -CaO-Nb ₂ O ₅ system.

[0004]

However, in the above dielectric ceramic, the firing temperature is too high to fire at the same time as Ag,
In addition, there is a problem that the mechanical strength is weak for use as a chip part.

An object of the present invention is to further sinter the above-mentioned dielectric ceramic at a low temperature and to improve the mechanical strength.

[0006]

The present invention is configured as follows to solve the above problems. In other words, bismuth oxide, the composition comprising calcium oxide and niobium _{oxide, xBiO 3/2 -yCaO-zNbO 5/} 2 ( provided that, x + y + z = 1.0 ) in the ternary composition diagram of when expressed as, x, y and z Is within a pentagonal region having the following A, B, C, D, and E as vertices (see FIG. 1), and at least Li, Na, K, V, Cr, Fe, Co, Ni, S
An oxide of one or more elements selected from n and W , or at least Ce, Pr, Nd, Sm, E
u, Gd, Tb, Dy, Ho, Er, and Yb are mixed so as to have a composition containing 1 part by weight or less of an oxide of one or more elements selected from the group, and sintered to obtain a dielectric ceramic composition. It has gained.

[0007]         A: (x, y, z) = (0.55, 0.16, 0.29)         B: (x, y, z) = (0.5, 0.21, 0.29)         C: (x, y, z) = (0.44, 0.24, 0.32)         D: (x, y, z) = (0.44, 0.2, 0.36)         E: (x, y, z) = (0.5, 0.175, 0.325)

[0008]

The above dielectric porcelain composition, in the absence of additives, has a limited composition region in air at 1050 ° C. or lower,
Alternatively, even in firing under a low oxygen partial pressure such as in N ₂ , it sinters densely, has a dielectric constant of 50 or more and an unloaded Q value of 3
00 or more, the absolute value of the resonance frequency temperature coefficient is 50ppm / ℃
The following excellent microwave dielectric properties are shown, but by adding the additive described in claim 1 or claim 2, the firing temperature is lowered without significantly deteriorating the dielectric properties, Alternatively, the mechanical strength can be improved.

[0009]

【Example】

(Embodiment 1) This embodiment corresponds to the invention described in claim 1.

Bi ₂ having a high chemical purity is used as a starting material.
O ₃ , CaCO ₃ , Nb ₂ O ₅ and CuO are used as the main component raw materials, and SiO ₂ , Li ₂ CO ₃ , Na ₂ CO ₃ and K are used.
₂ CO ₃ , V ₂ O 5, Cr ₂ O ₃ , MnO ₂ , Fe ₂ O
Any one or more of ₃ , Co ₂ O ₃ , NiO, SnO ₂ and WO ₃ was used as an additive.

The composition of the main component is 0.46 BiO _3/2
After selecting -0.215CaO-0.325NbO _5/2 and correcting the purity of the raw materials, various additives were weighed so as to have various amounts. These powders were placed in a polyethylene ball mill, and stabilized zirconia boulders and pure water (ethanol when the additive was an alkali metal oxide) were added and mixed for 17 hours. After mixing, the slurry was dried, put in an alumina crucible, and calcined at 800 ° C. for 2 hours. The calcined body was crushed by a raikai machine, crushed by the above-mentioned ball mill for 17 hours, and dried to obtain a raw material powder. To this powder was added 6% by weight of a 5% aqueous solution of polyvinyl alcohol as a binder, and after mixing, the mixture was granulated through a 32 mesh sieve, and at 100 MPa, a diameter of 13 mm and a thickness of about 5 mm.
Was pressed into a cylindrical shape. The molded body was heated at 650 ° C. for 2 hours to incinerate the binder, put in a magnesia container, covered, and held in air at 850 to 1100 ° C. for 2 hours for firing.

The dielectric properties in microwave were measured for the sintered body that was fired at the temperature at which the density was maximized. The resonance frequency and the unloaded Q value were obtained by the dielectric resonator method. The dielectric constant was calculated from the dimensions of the sintered body and the resonance frequency. The resonance frequency was 3 to 5 GHz. In addition, the resonance frequencies at -25 ° C, 20 ° C, and 85 ° C were measured, and the temperature coefficient (τ _f ) was calculated by the least square method. The results (Table 1)
Shown in.

[0013]

[Table 1]

As shown in (Table 1), when the amount of the additive included in the scope of claims was added, the firing temperature could be lowered without substantially lowering the dielectric property. More than the quantity stated in the claims, ie 1
Addition in excess of parts by weight markedly deteriorated the dielectric properties.

(Embodiment 2) This embodiment corresponds to the invention described in claim 2.

As the main component raw material, the same material as in Example 1 was used. As starting materials for the additives, Al ₂ O ₃ , TiO ₂ ,
CeO ₂ , Pr ₆ O ₁₁ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu
₂ O ₃ , Gd ₂ O ₃ , Tb ₄ O ₇ , Dy ₂ O ₃ , Ho ₂
O ₃ , Er ₂ O ₃ , and Yb ₂ O ₃ were used.

Hereinafter, the production of the sintered body and the evaluation of the characteristics were performed in the same manner as in Example 1. Mechanical strength is 3
A rectangular parallelepiped sample of × 2 × 40 mm ³ was prepared and measured by the three-point bending method. It was calculated from the average value of 10 samples. The results are shown in (Table 2).

[0018]

[Table 2]

As shown in (Table 2), when the amount of the additive included in the claims was added, the mechanical strength could be improved without substantially lowering the dielectric property.

Addition in an amount more than the amount specified in the claims, that is, more than 1 part by weight, markedly deteriorated the dielectric properties.

[0021]

INDUSTRIAL APPLICABILITY As described above, the dielectric ceramic composition of the present invention sinters at a low temperature, has excellent mechanical strength, and has excellent dielectric properties in the microwave range. By using this dielectric porcelain, it is possible to fabricate a laminated microwave device using a conductor having high conductivity such as Cu or Ag. In particular,
Since a small resonator system can be formed, it largely contributes to downsizing of microwave devices such as car phones and portable phones.

Further, the dielectric ceramic composition of the present invention can be used as a circuit board for microwaves and the like, and has great industrial value.

[Brief description of drawings]

1 is a main component of a dielectric ceramic composition of the present invention Bi
The claims of ₂ O _3, CaO and Nb ₂ O ₅ is a diagram showing by hatching. Point P represents the composition used in the examples.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ichiro Kameyama 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP 62-12002 (JP, A) JP 47- 20695 (JP, A) Hiroshi Kagata et al, "Low-Fire Bismuth-Based Dielectric Ceramics for Microwave Use", Jpn. Appl. Phys. , Vol. 31 (1992) Part 1, No. 9B, September 1992, p. 3152-3155 "Dictionary of Chemistry, Editorial Committee," edited by the Chemistry Dictionary, September 15, 1938, published by Kyoritsu, p. 470 The Ceramic Society of Japan, "Ceramic Engineering Handbook", April 10, 1989, published by Gihodo, 1st edition, p. 2300 ~ 2302 (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01B 3/12 313 C04B 35/495 H01P 7/10 JISST file (JOIS)

Claims (2)

(57) [Claims] 1. A composition comprising bismuth oxide, calcium oxide and niobium oxide is added to xBiO _3/2 -yCaO-
In the three-component composition diagram when expressed as zNbO _5/2 (however, x + y + z = 1.0), x, y and z are within the pentagonal area having the following A, B, C, D and E as vertices, At least Li, Na, K, V, Cr, Fe, C
1. A dielectric ceramic composition containing 1 part by weight or less of an oxide of one or more elements selected from o, Ni, Sn and W. A: (x, y, z) = (0.55, 0.16, 0.2
9) B: (x, y, z) = (0.5, 0.21, 0.2)
9) C: (x, y, z) = (0.44, 0.24, 0.3
2) D: (x, y, z) = (0.44, 0.2, 0.3
6) E: (x, y, z) = (0.5, 0.175, 0.3)
25) 2. A composition comprising bismuth oxide, calcium oxide and niobium oxide is added to xBiO _3/2 -yCaO-
In the three-component composition diagram when expressed as zNbO _5/2 (however, x + y + z = 1.0), x, y and z are within the pentagonal area having the following A, B, C, D and E as vertices, At least Ce, Pr, Nd, Sm, Eu, Gd,
1. A dielectric ceramic composition comprising 1 part by weight or less of an oxide of one or more elements selected from Tb, Dy, Ho, Er and Yb . A: (x, y, z) = (0.55, 0.16, 0.2
9) B: (x, y, z) = (0.5, 0.21, 0.2)
9) C: (x, y, z) = (0.44, 0.24, 0.3
2) D: (x, y, z) = (0.44, 0.2, 0.3
6) E: (x, y, z) = (0.5, 0.175, 0.3)
25)