JPH0869715A - Dielectric ceramic composition for high frequency - Google Patents

Abstract

PURPOSE: To provide a dielectric ceramic composition having a high Q value and lower specific dielectric constant than conventional forsterite, etc., in the high frequency region by using a main component having a composition according to the specified equation, and adding as aux. component a specified quantity of ZnO. CONSTITUTION: As crude materials, MgO, SiO2 , Al2 O3 , and ZnO are used, and they are weighed so that a composition of specified proportion is generated and subjected to a specified processing. As main components the composition includes a general equation xMgO-ySiO2 -zAl2 O3 (where, x, y, z represent wt.% of the components, and the conditions should be met such that 60<=x<=90, 10<=y<=40, 0<=z<10, and x<=y<=Z=100). To these main components, one wt.% ZnO or less is added as aux. component. Thereby a high Q value is obtained in a high frequency band such as the microwave region, and a low dielectric constant is provided which is comparative with forsterite, and addition of ZnO ensures an improved sintering characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency dielectric porcelain composition, and is particularly useful as a material for a circuit element substrate used in a microwave band such as a microwave integrated circuit or a support for a dielectric resonator. The present invention relates to a high-frequency dielectric ceramic composition.

[0002]

2. Description of the Related Art A high-frequency circuit element such as a microwave integrated circuit may have a structure in which a dielectric resonator is fixed to a substrate through a supporting base. It is necessary to use a material having a low dielectric constant and a low dielectric loss (tan δ). Therefore, conventionally, for example, forsterite is used as the material for the support base,
Further, for example, alumina porcelain has been adopted as a material for the porcelain substrate.

[0003]

However, although forsterite has a small relative permittivity (εr) of about 6.5, it has a Q value of about 7,000 at 10 GHz. It cannot be said to be sufficient, and a material having a higher Q value is required. Alumina porcelain, which is mainly used for porcelain substrates, has a high Q value of 20,000 to 30,000 at 10 GHz, but has a high relative permittivity of 9 to 10, so if a high-impedance stripline is formed, the line If the width is too small (usually 1 μm or less), there is a problem that disconnection occurs or relative line width variation increases, and the defect rate of the microwave integrated circuit increases.

An object of the present invention is to provide a dielectric ceramic composition having both a high Q value and a low relative dielectric constant in the high frequency region as compared with conventional forsterite and alumina.

[0005]

The invention according to claim 1 is
Formula _{xMgO-ySiO 2 -zAl 2 O 3} ( where in the formula, x, y, z are, represents the weight percentage of each component, 60 ≦
x ≦ 90, 10 ≦ y ≦ 40, 0 ≦ z <10, x + y + z
= 100) as a main component, and 1% by weight or less of ZnO as a subcomponent is added to the main component to provide a high frequency dielectric ceramic composition.

The reason for limiting the composition range of the claims is as follows. Regarding the x value of xMgO, the Q value is low when x <60% by weight, and the relative dielectric constant is high when x> 90% by weight. Further, when the y value of ySiO ₂ is y <10% by weight, the relative dielectric constant is high, and when the y value is 40% by weight, the Q value is low. Furthermore, when the z value of zAl ₂ O ₃ is z ≧ 10% by weight, the Q value becomes low. The additive ZnO was set to 1.0% or less (excluding 0%) because the sinterability was poor unless ZnO was added.
This is because the Q value becomes low when the content exceeds 1.0%.

[0007]

According to the present invention, the general formula xMgO-ySiO
_{2 -zAl 2} O ₃ (where in the formula, x, y, z are, represents the weight percentage of each component, 60 ≦ x ≦ 90,10 ≦ y ≦ 4
0, 0 ≦ z <10, x + y + z = 100) as a main component, and ZnO as a sub-component with respect to the main component.
When 1% by weight or less is added, a dielectric ceramic composition having a high Q value, a low relative dielectric constant and good sinterability can be obtained.

[0008]

Embodiments of the present invention will be described below.
MgO, SiO ₂ , Al ₂ O ₃ and ZnO were used as raw materials, and these were weighed so as to obtain the composition in the ratio shown in Table 1, wet-mixed for 16 hours, and then evaporated to dryness, and this mixture was heated at 1200 ° C. After calcination for 2 hours, it was crushed. Add an appropriate amount of binder to the obtained calcined powder and granulate.
Molding was performed under a pressure of 00 kg / cm ² to obtain a molded body having a diameter of 22 mm and a thickness of 11 mm. This molded body was placed in the air at
The dielectric ceramic sample was obtained by firing at ˜1600 ° C. for 4 hours. The dielectric characteristics of the obtained dielectric ceramic sample at 10 GHz were measured by the dielectric resonator method. The results are shown in Table 1.

[0009]

[Table 1]

In Table 1, the sample numbers marked with * are outside the scope of the present invention, and the others are within the scope of the present invention. Further, FIG. _{1, xMgO-ySiO 2 -zAl 2 O} 3 Among the compositions according to the present invention
X, y, and z of the composition range.
The inside of the figure surrounded by A, B, C, and D in the drawing is within the scope of the claims. However, the line AB is not included.

From these results, the high frequency dielectric ceramic composition according to the present invention has a low relative permittivity of 7 to 8, and has a Q
It can be seen that the value is as high as 20000 to 30000, which is as high as that of alumina.

Until now, it has been known that the compositions near the sample numbers 2, 3, 5, and 6 have a low relative dielectric constant.
It is difficult to sinter completely because it is difficult to sinter,
High Q value could not be obtained. As is apparent from Sample Nos. 9 and 18, the addition of ZnO improves the sinterability and realizes a low relative dielectric constant and a high Q value.

[0013]

According to the present invention, the general formula xMgO-y
SiO ₂ -zAl ₂ O ₃ (where in the formula, x, y, z are,
Represents the weight percentage of each component, 60 ≦ x ≦ 90, 10 ≦ y
≦ 40, 0 ≦ z <10, x + y + z = 100) as a main component, and Z as a sub-component to the main component.
By adding no more than 1% by weight of nO (excluding 0% by weight), Q value of 20,000 at 10 GHz
~ 30000, which is very high, and the dielectric constant is as low as 7-8,
A high frequency dielectric ceramic composition having improved sinterability can be obtained.

That is, by using the high frequency dielectric porcelain composition of the present invention, it has a high Q value in a high frequency band such as a microwave region and a low relative permittivity comparable to forsterite. A high frequency dielectric ceramic useful as a material for a circuit element substrate or a dielectric resonator support used in a band can be obtained.

Further, the addition of ZnO improves the sinterability, and even in the composition which has been difficult to sinter completely until now, a good sintered body can be obtained, and a low relative dielectric constant and A high frequency dielectric ceramic composition having a high Q value can be obtained.

[Brief description of drawings]

FIG. 1 is a ternary composition diagram showing a composition range of a high frequency dielectric ceramic composition of the present invention.

Claims (1)

[Claims] 1. A general formula xMgO-ySiO ₂ -zAl ₂ O
₃ (where x, y, and z represent weight percentages of the respective components, and 60 ≦ x ≦ 90, 10 ≦ y ≦ 40, 0 ≦ z <1
0, x + y + z = 100) as a main component, and ZnO of 1 wt% or less (not including 0 wt%) as a sub-component is added to the main component. High frequency dielectric ceramic composition.