JPH0520841B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Fields The present invention is directed to ammina porcelain compositions used in the telecommunications field such as microwave dielectric resonators, microwave integrated circuit boards, packages, and microwave waveguides, and in the high-energy physics field such as microwave transmission windows. It is about things. BACKGROUND ART In recent years, with the development of communication networks, the frequency range in use has expanded to include microwaves. In connection with this, dielectric porcelain can be used in the microwave frequency range.
It is applied to dielectric resonators, microwave integrated circuit boards, and impedance matching of various microwave circuits. In particular, recently, a large number of microwave circuits are required to stabilize the frequency of filters, guns, or FET microwave oscillators, and the demand for them has increased. The size of this microwave circuit is based on the wavelength of the electromagnetic wave, and when the electromagnetic wave propagates in a microwave three-dimensional circuit using a dielectric, the wavelength in vacuum is λ ₀ , and the relative dielectric constant is λ 0 . When the rate is ε, it is λ ₀ /ε. On the other hand, alumina porcelain has high mechanical strength, low dielectric loss, and low cost, so it is expected to be used in the communication field mentioned above. Problems to be Solved by the Invention Barium titanate, calcium titanate, alumina, forstellite, etc. are used as microwave capacitor materials, but these all have insufficient temperature coefficient of dielectric constant or high frequency loss. A solution was desired as the characteristics could not be obtained. Means for Solving the Problems The present invention has been made to solve the above problems, and includes 0.1 to 3 weight of La ₂ O ₃ based on the total amount of the three components Al ₂ O ₃ −SnO ₂ −TiO ₂ . % of alumina porcelain, especially Al ₂ O ₃ −SnO ₂ −
If the blending ratio of TiO ₂ is within a triangle with the following points as apexes in the three-component composition diagram expressed in mole fraction, an alumina porcelain composition with extremely excellent properties and other properties is provided. can do. Al ₂ O ₃ SnO ₂ TiO ₂ Point 1 0.925 0.04 0.035 Point 3 0.65 0.25 0.10 Point 5 0.65 0.075 0.275 (Mole fraction) Here, if Al ₂ O ₃ becomes richer than point 1, 〓ε
takes a positive value with an excessive absolute value, and if it is less than the line segment 3-5, ε takes a negative value with an excessive absolute value, and
tanδ becomes excessive. Further, even if Al ₂ O ₃ is within the above range, if SnO ₂ and TiO ₂ are out of the above range and become richer than line segment 1-3 and line segment 5-1, respectively, tan δ becomes excessive. In the present invention, in addition to the above points 1, 3, and 5, La ₂ O ₃ is added to the total amount of Al ₂ O ₃ −SnO ₂ −TiO ₂
It is necessary to add 0.1 to 3% by weight. In other words, when the amount of La ₂ O ₃ added is less than 0.1% by weight, the effect of improving dielectric loss characteristics is insufficient;
If it exceeds 3% by weight, the characteristics of temperature coefficient and dielectric loss will deteriorate significantly. Examples A ceramic composition according to the present invention and a ceramic composition according to a comparative example were manufactured according to the procedure shown below. Alumina (commercially available, purity 99.995%) Specified amount of tin oxide (special grade reagent) Titanium dioxide (special grade reagent) Lanthanum oxide (special grade reagent) Specified amount of the above 300 g Polyvinyl alcohol 1.5 g Deionized water 200 ml or more with a diameter of 15 mm, The slurry was put into a polyethylene bottom mill with an internal volume of 1 and mixed with 1 kg of alumina coccules having a purity of 99.99% for 48 hours at 120 rpm. The resulting slurry was freeze-dried and then passed through a 32-mesh sieve to form a base powder. This base powder was press-molded with a mold at a pressure of 1500 kg/cm ² , fired at the temperature shown in the table, and polished to produce an alumina porcelain sample with a size of 3.5φ×6 ^t mm. Next, this sample was ultrasonically washed with chlorocene and deionized water for 20 minutes each, air-dried, and then its dielectric properties were measured under the following conditions. Measurement conditions Method: Dielectric cylinder resonance method Equipment: 8410C network analyzer system manufactured by Yokogawa Heuretsu Card Co., Ltd. Frequency: 13GHz The composition of Al ₂ O ₃ −SnO ₂ −TiO ₂ is as shown in the following table. It is also plotted in the triangular diagram.

[Table] Regarding the total amount of the above Al ₂ O ₃ −SnO ₂ −TiO ₂ composition
La ₂ O ₃ at 0, 0.05, 0.1, 0.5, 3, and 5% by weight
Prepare a sample with the addition of ε, tanδ (×10 ^-5 ), 〓ε
(ppm/°C) was measured. Table 2 shows the data, the firing temperature T° C. of the sample, and the inside and outside of the scope of the invention.

【table】

[Table] The preferable tan δ (×10 ^-5 ) is 20, and 〓
ε (ppm/°C) is 1140. Effects of the Invention According to the present invention, ε is almost the same as that without adding La ₂ O ₃ , tan δ is relatively small at 20, and 〓ε
The absolute value is 40, which is excellent, and the firing temperature is the same as that without adding La ₂ O ₃ , so it has various effects such as no disadvantages in manufacturing.

[Brief explanation of the drawing]

FIG. 1 shows the components of the porcelain composition of the present invention, Al ₂ O ₃ ,
FIG. 2 is a ternary composition diagram showing preferred ranges of SnO ₂ and TiO ₂ .

Claims (1)

[Scope of Claims] 1 In a ternary composition diagram in which the blending ratio of a ternary porcelain composition consisting of Al ₂ O ₃ −SnO ₂ −TiO ₂ is expressed in terms of mole fraction, it is represented by a straight line connecting each point below. An alumina porcelain composition containing 0.1 to 3% by weight of La ₂ O ₃ based on the total amount of Al ₂ O ₃ −SnO ₂ −TiO ₂ within the range of Al ₂ O ₃ SnO ₂ TiO ₂ points 1 0.925 0.04 0.035 points 2 0.65 0.25 0.10 points 3 0.65 0.075 0.275 (mol%)