JPS60208007A - Microwave high dielectric constant dielectric porcelain composition - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a novel micro-component, which has a large dielectric constant, low dielectric loss in the microwave region, and good temperature characteristics, and is useful for miniaturizing microwave ICs, etc. The present invention relates to a high dielectric constant dielectric ceramic composition for waves.

Conventionally, dielectric materials have also been used in the microwave region, for example, as impedance matching elements in microwave circuits, dielectric resonators, substrates of microwave integrated circuits (microwave ICs), and the like.

BACKGROUND ART For some time now, with the progress of microwave IC circuit technology and the expansion of the frequency range in which they can be used, there has been a demand for miniaturization of microwave ICs, especially those used in the microwave range with relatively long wavelengths.

Therefore, there is a demand for a dielectric material for microwaves that satisfies the following requirements. First of all, microwave I
In order to miniaturize C, it is necessary that the dielectric material has a high dielectric constant ε. For example, in order to reduce the size of a microwave IC to about 1/9th of the conventional size (approximately 1/9), it is necessary to use a substrate that is at least nine times as large as alumina (relative permittivity εz10), which has been used as a conventional substrate. It is necessary that the dielectric constant, that is, the relative dielectric constant ε≧90. In addition, it is necessary that the change in relative permittivity with respect to temperature is small, and the temperature coefficient of permittivity of high-purity alumina τε: +I 20 pp
m/℃, temperature coefficient of blood-coagulability improved by introducing magnesium oxide MgO τεχ + 1801) I) In
/ ℃, so it is at least equivalent to the above-mentioned high purity alumina, that is, the temperature coefficient τε≦±150p
It is desirable that the temperature is pm/°C. Furthermore, microwave I
Although the loss in the strip line in C consists of conductor loss and dielectric loss, it is preferable that this loss is determined substantially only by conductor loss. Therefore, the Q (QO) in the no-load state determined by the dielectric loss should be sufficiently larger than the Q (usually 200 to 300) of the microwave strip line, at least at a frequency of 3GI-Tz, for example.
;:= Desirably 1000.

However, no conventional dielectric material is known that satisfies all of the above requirements. For example, dielectric compositions for temperature compensation capacitors have been known as dielectric materials with a relatively large relative dielectric constant ε and good temperature characteristics, but these compositions do not have dielectric properties in the frequency range of several MHz. Although the loss is low, it has the disadvantage that the dielectric loss becomes too large in the microwave region.

For example, BaTi0a-YzOs-TiO2-'J'i
For Oz-based compositions, at 1 MHz, Qo=1670
However, QO=160 at 3 GHz.

The present inventors met the above-mentioned requirements for dielectric properties, that is, at a frequency of 31 JHz, relative dielectric constant ε≧90, temperature coefficient τ,≦
As a result of intensive research to develop a high permittivity dielectric ceramic composition for microwave use that satisfies ±150ppm/'C, Qo≧1000, we found that barium oxide, neodymium oxide, titanium oxide, bismuth oxide, chromium oxide, or iron oxide. The present invention was completed based on the discovery that a dielectric ceramic composition prepared by solid-phase reaction by mixing a predetermined range of the following is suitable for this purpose.

That is, the high dielectric constant dielectric ceramic composition for microwaves according to the present invention has the general formula (] -W ) [alJao・b
N d20a・cTiQ2・dBi20g]+wMz
oa (However, M in the formula does not represent Cr or Fe.)
A composition represented by, whose composition range is 0.14≦a≦0.18 0.14≦b≦0.18 0.62≦C≦0.72 0.005≦d≦030 a + b + C 10d=10<W≦0.005, and the microwave IC
It can be miniaturized without impairing its characteristics, making it suitable as a dielectric for devices such as capacitors in the microwave region.

In the present invention, the composition range of each component is important, and the addition of CrzOa or i'ezOa is important.

That is, first, if the molar fraction of BaO is less than 0.14, the dielectric constant ε decreases, making it difficult to ensure ε=90, and furthermore, the temperature coefficient τε also becomes too large. On the other hand, when the molar fraction a of B a O exceeds 0.18, the dielectric loss becomes too large.

Next, if the molar fraction of Nd2011 is less than 0.14, the temperature coefficient τε becomes large and the relative dielectric constant ε<90
It becomes. Moreover, the mole fraction of NdzOa is 0.
If it exceeds 18, the dielectric constant ε will actually decrease, making it impossible to secure the desired dielectric constant ε.

Furthermore, if the mole fraction C of TlO2 is less than 0.62, the dielectric constant will similarly be 90, and the dielectric loss will become too large, which is inappropriate.

Conversely, if the molar fraction C of TlO2 exceeds 0.72, the temperature coefficient τε becomes too large, which is inappropriate.

Sarani Mata, 13izOa (7) mole fraction d ha (1,
(l O5”l.

It is preferable that d≦0.030. FIG. 1 does not show the relationship between the mole fraction d of B i 20a and QO. In addition, Bad: NdzOa: i"i0220.
172:0°+53:0.660 (content ratio constant), and the molar fraction of Cr20a is 0.001.

It can be seen from FIG. 1 that even if the mole fraction d of BizOa is too small, or if the mole fraction d is too large, the QO becomes small and the dielectric loss becomes large. Also,
FIG. 2 shows the relationship between the mole fraction d of BizOa and the temperature coefficient ε. From this figure 2, the mole fraction d of BizOs is 0.
．． It can be seen that when the temperature coefficient τε is 005 or more, the temperature coefficient τε is significantly improved. Furthermore, it has been found that when the mole fraction d of Biz03 above exceeds 0.030, the sinterability decreases and the dielectric constant ε also becomes 90 or less. Therefore,
The practical range is 0.005≦d≦0.030.

For compositions in the above composition range, M2O3 (M is Cr
Or represents Fe. ) is added. It is preferable that the amount W of M2O3 added is Q(w≦0.005. If the above M 20 a is not added, dielectric loss is likely to increase due to minute fluctuations in the amount of oxygen, and the amount W of M2O3 added is If it exceeds 0.005, the dielectric loss due to the additive becomes large.

By the way, the high permittivity dielectric material a for microwaves according to the present invention
im compositions include, for example, BaCX)a, NdzOa,
i”i02, Biass and CrzOa7 or F
e2O20) Mix a predetermined amount of each raw material powder and heat from 1350 to
It can be manufactured by firing at a firing temperature of about 1450°C, and the manufacturing method will be described below.

In order to produce the dielectric ceramic composition of the present invention, first, 13acOa and NdzO each having a purity of 99.9% or more are prepared.
Raw material powders of s, Ti0z, BizOa, and CrzOa or FezOa are prepared.

Next, each of these raw material powders is weighed so as to have a predetermined composition, wet-mixed in a ball mill, and then dried.

Subsequently, the molded product was subjected to pressure molding at a pressure of 1,000 kg/cffl, and the molded product was heated in air at 1,000 to 1,100°C.
Bake for 3 hours.

Further, the calcined product is pulverized using a mortar or the like, and wet-mixed again using a ball mill and dried.

Finally (B) The above-dried product is pressure-molded at a pressure of 1500 kg/cfl and fired in air at a temperature of +350-1450'C0 for 3 hours.

According to the above manufacturing method, the mole fraction of each component and Cr2Og
Alternatively, dielectric ceramic compositions were prepared by varying the amount of FezOa added, and the dielectric properties of each were measured.

The results are shown in Tables 1 and 2. The above dielectric properties are determined by processing the obtained dielectric ceramic composition into a cylindrical dielectric resonator, and determining the relative dielectric constant ε, temperature coefficient τε, and QO based on the resonance characteristics, temperature change, and dimensions of the resonator. I met. At this time,
Measurement frequency is 3Qllz, temperature change range is -20 to +6
It was 00G.

Examples 1 to 15 shown in Table 1 satisfy the composition range of the present invention, and have excellent properties in terms of dielectric constant ε, temperature coefficient τε, and Qo. It can be seen that the above-mentioned requirements are satisfied. Also, M
It can be seen that the same effect can be obtained by using either Cr20a or Fe20g as 20a.

In contrast, Comparative Examples 1 to 15 shown in Table 2
It can be seen that any of the compositions of each component is outside the above-mentioned composition range, and therefore the required dielectric properties are not satisfied.

As described above, the high-permittivity dielectric material composition for microwaves according to the present invention can significantly improve dielectric properties, and can miniaturize microwave ICs. It becomes possible. For example, compared to microwave ICs using alumina substrates, the area is approximately
/lo or less). Furthermore, since it has good dielectric properties, it is suitable as a dielectric material for devices such as capacitors in the microwave region.

[Brief explanation of the drawing]

Figure 1 is a characteristic diagram showing the relationship between the mole fraction of Bi20a and Qo, and Figure 2 is a diagram showing the relationship between the mole fraction of BizOs and the temperature coefficient τ.
FIG. 3 is a characteristic diagram showing the relationship between ε. Patent applicant Sony Corporation representative Patent attorney Kodo Koike 1) Toshiei - Bitchichiβi7It-e'1ijd -Bii03
Contains 1 and 0 rumors-d.

Claims (1)

[Claims] General formula (1-w) [aHao-bNdzoa・cTio
z-dBizoa]+wMzoa (in the formula, M represents Crg or pe),
The composition range is 0.14≦a≦0.18 0.14≦b≦0.18 0.62≦C≦0.72 0.005≦d≦0.030 a ten b ten c ten d = ] Q (A high dielectric constant dielectric ceramic composition for microwave use, characterized in that w≦0.005.