Dielectric ceramic composition for high frequency wave

Details Dielectric ceramic composition for high frequency wave Dielectric ceramic composition for high frequency wave

2001-10-22

2003-12-09

Brunsman, David (Department: 1755)

Compositions: ceramic

Ceramic compositions

Titanate, zirconate, stannate, niobate, or tantalate or...

Reexamination Certificate

active

06660674

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a dielectric ceramic composition for high frequency wave having a specific dielectric constant &egr;
r
of 10 to 20, and less dielectric loss tan &dgr; in a high frequency wave region, and capable of easily controlling temperature coefficient &tgr;
f
at the resonant frequency (f
0
)
2. Description of the Related Art
With the rapid progress of communication networks in recent years, frequencies used for communication have been extended and reached high frequency wave regions such as microwave regions or milli-wave regions. The size of the microwave circuits or milli-wave circuits can be miniaturized as a specific dielectric constant &egr;
r
is larger. However, if the specific dielectric constant &egr;
r
is excessively large, the fabrication accuracy is lowered regarding the high frequency region higher than the microwave region. Therefore, materials having relatively small specific dielectric constant &egr;
r
are necessary.
As the dielectric ceramic composition of this type, for example, BaO—MgO—WO
3
series materials (Japanese Patent Laid-Open No. 236708/1994) and Al
2
O
3
—TiO
2
—Ta
2
O
5
series material (Japanese Patent Laid-Open 52760/1997) have been proposed. However, they are not yet sufficient regarding the characteristics as the high frequency wave use and, a dielectric ceramic composition having further excellent characteristics has been demanded. Furthermore, from the point of mass production, less scattering of the characteristic against firing temperature fluctuation is requested.
Meanwhile, alumina (Al
2
O
3
) exhibits satisfactory dielectric characteristics having a specific dielectric constant &egr;
r
of 9.8 and tan &dgr; of 3 to 5×10
−5
at a measuring frequency of 10 GHz but since the temperature coefficient &tgr;
f
at the resonance frequency (f
0
) is −55 ppm/° C., the application use is restricted. Further, the firing temperature of Al
2
O
3
is as high as 1600° C. or higher to result in a problem that the cost for the firing step is increased.
SUMMARY OF THE INVENTION
This invention intends to eliminate the problems described above and provide a dielectric ceramic composition for high frequency wave having a specific dielectric constant &egr;
r
of 10 to 20 and dielectric loss less tan &dgr;, which is less scattering, and the absolute value of a temperature coefficient &tgr;
f
at the resonance frequency (f
0
) of 30 ppm/° C. or less, which can easily be controlled.
This invention relates to a dielectric ceramic composition for high frequency wave having a composition comprising, Al, Zr, Ti, Sn, and O as a basic component and represented by the compositional formula:
a
Al
2
O
3
-
b
ZrO
2
-
c
TiO
2
-
d
SnO
2
(in which 0.4068<a<0.9550, 0<b<0.1483, 0.0225<c<0.3263, 0.0203<d<0.1186, a+b+c+d=1).
This invention can provide a dielectric ceramic composition for high frequency wave having a specific dielectric constant &egr;
r
of 10 to 20 and less dielectric loss tan &dgr; in a high frequency wave region, which is less scattering against firing temperature fluctuation, and capable of easily controlling a temperature coefficient &tgr;
f
at the resonant frequency (f
0
).


REFERENCES:
patent: 4866016 (1989-09-01), Ando et al.
patent: 5132258 (1992-07-01), Takahashi et al.
patent: 5432135 (1995-07-01), Hirahara et al.
patent: 62-119157 (1987-05-01), None
patent: 63-76206 (1988-04-01), None
patent: 6-236708 (1994-08-01), None
patent: 9-52760 (1997-02-01), None

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