JP4468155B2 - Microwave dielectric ceramic composition for low temperature firing and manufacturing method thereof - Google Patents

Description

  The present invention relates to a microwave dielectric ceramic composition for use in various communication electronic device parts, and more particularly, a high dielectric constant, a quality factor, and a temperature coefficient of a stable resonant frequency (Temperature Coefficient of Resonant Frequency: TCF). The present invention relates to a microwave dielectric ceramic composition for low-temperature firing that can be fired in a low temperature range of 880 to 960 ° C. and a method for producing the same.

  Recently, with the development of information / communication technologies such as mobile communication and satellite broadcasting, the frequency used for communication components is gradually becoming a microwave region. In particular, not only in new mobile communication services such as IMT-2000, but also in existing mobile phones, GPS (Global Positioning System), and satellite communication fields, high frequency in a frequency band for exchanging more capacity information. And digitization are progressing. Accordingly, the importance of communication devices operating in the microwave region has emerged.

  Electronic components used for mobile communication are roughly divided into active components and passive components. In particular, passive components such as duplexers, filters, and antennas use microwave dielectric ceramics as the core material. In order to use a dielectric ceramic for a microwave device, it must have a large dielectric constant, and for this reason, in order to reduce the dielectric loss, it must have a high quality factor. Also, in order to stabilize the resonance frequency of the microwave device and facilitate temperature compensation of the resonance circuit, the temperature coefficient of the resonance frequency of the dielectric material used as the resonance element must be reduced.

  Recently, modularization of individual components such as MMIC (Microwave Monolithic IC) has been attempted in order to reduce the size, integration, and functionality of mobile communication devices. This is called MCMC (Multi-Chip Module on Ceramics). ) Technology makes it possible. MCMC technology uses antennas, duplexers, bandpass filter elements, etc., in which ceramic is used as individual parts in a laminated form, and sinters simultaneously with metal electrode patterns to make the parts smaller and mass-produced. It is a technology that can. This can be realized by LTCC (Low temperature cofiring ceramic) technology.

  In the case of a microwave dielectric ceramic composition that is currently being developed, the sintering temperature is as high as 1200 ° C. or higher, so that Pt, Pd, or W, which is a metal electrode having a high melting point, must be used. However, when Pt or Pd is used for an electrode, these metals are expensive, so there is a problem that the production cost is considerably increased. In the case of W, the problem is that sintering must be performed in a reducing atmosphere. There is. Therefore, attempts are being made to use Ag (melting point 960 ° C.) or Cu (melting point 1083 ° C.), which is relatively inexpensive and excellent in electrical conductivity, as the internal electrode. In order for microwave dielectric ceramics to be co-fired with Ag or Cu, it must be possible to sinter at temperatures below the melting point of these electrodes, so low temperature sintering with a sintering temperature corresponding to that temperature. A ceramic dielectric is required.

  The low-temperature sintered ceramic dielectrics reported to date are mainly made by adding a glass frit having a low melting point to the conventional dielectric composition to lower the sintering temperature, or by coprecipitation or sol- A method of reducing the particle size of a dielectric ceramic raw material using a gel method has been made. However, when glass frit is added, there is a disadvantage in that the dielectric characteristics are greatly reduced. When the dielectric ceramic raw material particle size is reduced by the coprecipitation method or the sol-gel method, the manufacturing process is complicated. However, the starting material is expensive and the manufacturing cost is high.

On the other hand, bismuth is a substance that has been widely taken up as an aid for liquid sintering of ceramics because of its low melting point (825 ° C.). Ceramic materials based on this have a relatively low sintering temperature, and research is underway to use bismuth-based ceramics as microwave dielectrics. BiNbO _{4 system,} Bi ₂ O 3 -CaO _{based, Bi 2 O 3 -CaO-ZnO} -Nb 2 O 5 system, etc. to the addition of various sintering aids dielectric ceramic capable low-temperature sintering is developed Yes.

Of these, the composition in which CuO and V ₂ O ₅ were added as sintering aids to BiNbO ₄ showed the most preferable dielectric properties, but the dielectric properties were still insufficient for application as actual parts. There is still a need for dielectric compositions that have excellent dielectric properties and can be sintered at low temperatures.

  The present invention has a high dielectric constant, quality factor and temperature coefficient of a stable resonance frequency, can be fired in a low temperature range of 880 to 960 ° C., and can use Ag or Cu for an internal electrode. An object of the present invention is to provide a body ceramic composition and a method for producing the same.

  Hereinafter, the microwave dielectric ceramic composition and the manufacturing method thereof according to the present invention will be described in detail.

  The microwave dielectric ceramic composition according to the present invention has a composition represented by the following formula 1 or 2.

Bi _1-x A _x NbO ₄ (1)
BiNb _1-x B _x O ₄ (2)
(In the formula, A is Sm or Dy, B is Sb or P, and x is 0 <x ≦ 0.1.)

  The dielectric composition according to the present invention has a dielectric constant of 40 or more, a quality factor of 20,000 to 42,000, and a temperature coefficient of resonance frequency of −2 to −26. Moreover, it can sinter in the temperature range of 880-960 degreeC, and baking is possible with Ag or Cu with low melting | fusing point.

In addition, the dielectric ceramic composition according to the present invention may include CuO or V ₂ O ₅ as a sintering aid. In this case, a more preferable sinterability is exhibited when both CuO and V ₂ O ₅ are included than when either one of CuO or V ₂ O ₅ is included. The content of the sintering aid is 0.03 to 0.5% by weight with respect to the entire composition, 0.03 to 0.25% by weight of CuO and 0.03 to 0.25% by weight. It is more preferable that V ₂ O ₅ is contained. When the addition amount of the sintering aid is less than 0.03% by weight, sufficient sinterability cannot be exhibited, and when the addition amount of the sintering aid exceeds 0.5%, sintering is not possible. However, there is a problem that the dielectric properties are lowered.

The dielectric ceramic composition according to the present invention can be manufactured by a general oxide synthesis method. For example, it can be manufactured as follows.
Bi ₂ O ₃ , Nb ₂ O ₅ , and a compound having an element of Sb ⁺⁵ , P ⁺⁵ , Sm ⁺³ or Dy ⁺³ are wet-mixed in a solvent at a predetermined stoichiometric composition ratio, dried, and then heat-treated. Can be manufactured.

Moreover, the powder of the composition of Bi _1-x A _x NbO ₄ (A = Sm or Dy) or BiNb _1-x B _x O ₄ (B = Sb or P) thus produced is used as a sintering aid. A certain amount of CuO and / or V ₂ O ₅ can be added, wet-mixed and dried, and then sintered.

In the above, the compounds having an element of Sb ⁺⁵ , P ⁺⁵ , Sm ⁺³ or Dy ⁺³ include, but are not limited to, Sb ₂ O ₅ , H ₃ PO ₄ , Sm ₂ O ₃ , Dy ₂ O _{3 and the} like. It is not a thing.

Hereinafter, the present invention will be described in more detail through examples and reference examples . However, the present invention is not limited to the following examples and reference examples .

In this example and reference example , Bi ₂ O ₃ , Nb ₂ O ₅ , Sb ₂ O ₅ , H ₃ PO ₄ , Sm ₂ O ₃ and Dy ₂ O ₃ having a purity of 99.9% or more are used as basic raw materials. CuO and V ₂ O ₅ having a purity of 99% or more were used as sintering aids for promoting low temperature sintering. Powder synthesis _{BiNb 1-x B x O 4} (B = Sb +5, P +5) and ^{_{Bi 1-x A x NbO 4}} (A = Sm +3, Dy +3) General oxide synthesis with respect to the composition of the Was used.

  Each starting material was measured with an electronic balance according to the stoichiometric composition ratio, and then wet-mixed for 24 hours using ethanol as a solvent and stabilized zirconia balls having a diameter of 10 mm. After mixing, the mixture was dried for 24 hours using a dryer, and the dried powder was placed in an alumina crucible and calcined at 800 ° C. for 2 hours.

As a sintering aid, the thus obtained calcined powder having the composition of BiNb _1-X B _X O ₄ (B = Sb or P) or Bi _1-X A _X NbO ₄ (A = Sm or Dy) is used. A certain amount of CuO and V ₂ O ₅ were added and again wet-mixed with ethanol using a stabilized zirconia ball for 24 hours, and then again dried using a dryer for 24 hours. Granulated with a mesh sieve. The granulated powder composition was uniaxially molded at a pressure of 1.03 MPa (150 psi ) using a mold having a diameter of 12 mm, and then cold isobar- molded at a pressure of 137.8 MPa ( 20,000 psi ) . The molded specimen was sintered in the air at 880 to 960 ° C. for 2 hours at a heating rate of 5 ° C./min and then cooled in the furnace.

  The sintered specimens thus obtained were presented by Hakki and Coleman using a network analyzer of Hewlett Packard (HP 8720C), and Kobayashi and Tanaka. Is measured using the post resonant method (Non-patent Document 1) corrected by the above, and the change of the resonance frequency at each temperature is measured by the following equation (1) to obtain the temperature coefficient of the resonance frequency. It was. The results are shown in Tables 2-6.

Y. Kobayashi, and S. Tanaka, "Measurement of Complex Dielectric Constant by Columnar Dielectric Resionaror," Tech. Rept. CPM72-33, Institute of Electron and Communication Engineers of Japan (1972))

（式中、ｆ_Ｔ１＝温度Ｔ_１における共振周波数、ｆ_Ｔ２＝温度Ｔ_２における共振周波数、Ｔ_２＝８０℃、Ｔ_１＝２０℃である。）

( _Where f _T1 = resonance frequency at temperature T ₁ , f _T2 = resonance frequency at temperature T ₂ , T ₂ = 80 ° C., T ₁ = 20 ° C.)

Further, as a comparative example of the present invention, a ceramic composition having a BiNbO ₄ composition was produced in the same manner as described above, using Bi ₂ O ₃ and Nb ₂ O ₄ as starting materials. Each dielectric property was measured and the result is shown in Table 1.

As can be seen from these tables, the microwave dielectric ceramic composition according to the present invention can be sintered at a temperature of 960 ° C. or less, and has a dielectric constant and a dielectric constant higher than those of a dielectric ceramic composition having an existing BiNbO ₄ composition. Excellent quality factor characteristics and good temperature coefficient of resonance frequency. Specifically, in the case of a ceramic composition having a BiNb _1-x B _x O ₄ composition, the dielectric constant is 40 to 44, the quality factor is 14,000 to 42,000, and the Bi _1-x A _x NbO ₄ composition In the case of the ceramic composition, the dielectric constant was 40 to 42, and the quality factor was 20,000 to 32,000.

Claims (3)

A calcined powder having the composition of the following formula 1 or 2 is included as a main component, and 0.03-0.25 wt% CuO and 0.03-0.25 wt% V based on the total weight of the composition. A microwave dielectric ceramic powder composition for low-temperature firing, comprising ₂ O ₅ as a sintering aid.
Bi _1-x Dy _x NbO ₄ (1)
(In the formula, x is 0 <x ≦ 0.1.)
BiNb _1-x P _x O ₄ (2)
(In the formula, x is 0 <x ≦ 0.1.) A microwave dielectric ceramic sintered body obtained by sintering the powder composition according to claim 1. And H ₃ PO ₄ or _Dy 2 _{O 3,} after the _{Bi 2 O 3, Nb 2 O} 5, CuO and _V 2 _{O 5} were wet-mixed, the method comprising dried and then sintered, the following formula 1 or 2 A method for producing a microwave dielectric ceramic sintered body containing the composition as a main component .
Bi _1-x Dy _x NbO ₄ (1)
(In the formula, x is 0 <x ≦ 0.1.)
BiNb _1-x P _x O ₄ (2)
(In the formula, x is 0 <x ≦ 0.1.)