JP2893130B2 - Dielectric porcelain composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a dielectric ceramic composition which does not deteriorate in dielectric properties even in a strongly reducing atmosphere and can be surface-metallized with Mo-Mn or an activating metal. About.

(Prior Art) So far, alumina has been mainly used as a ceramic circuit board material. However, recently, there has been a development of a substrate having a high dielectric constant in order to reduce the size and cost by providing a capacitance component to the substrate, or to reduce the size of a strip line in a microwave circuit. It has been demanded.

Characteristics that can be applied to the substrate as described above include:
When forming a metal layer on the substrate surface by, for example, a Mo-Mn metallization method or an activated metal method, N ₂ -H _{2 is used} at 1000 ° C. to 1300 ° C.
It is required to be excellent in reduction resistance because it is exposed to a reducing gas atmosphere or a vacuum atmosphere.

On the other hand, non-reducing high dielectric constant materials include Ni and
Dielectric containing barium titanate as a main component (Japanese Patent Publication No. 57-42588, Japanese Patent Publication No. 60-20850, 60-20851) as a dielectric material for a multilayer ceramic capacitor having Cu or the like as an internal electrode.
And a temperature-compensating dielectric material containing calcium zirconate or strontium zirconate as a main component (JP-A-53-9853).
No. 100, U.S. Pat. No. 4,260,663), and a dielectric material containing calcium, strontium, and barium zirconate as a main component (JP-B-63-50309) has been proposed.

(Problems to be Solved by the Invention) However, among the above-mentioned dielectrics, the dielectric having barium titanate as a main component has a high dielectric constant of 5000 or more,
Although it can withstand the reducing atmosphere when co-firing with Cu and Cu,
In a strong reducing atmosphere such as Mo-Mn metallization, the insulation cannot be tolerated and the insulation is greatly reduced. In addition, dielectrics containing calcium zirconate or strontium zirconate as a main component can withstand a co-firing atmosphere with Ni or the like similarly to barium titanate, but have a drawback that the dielectric constant is as small as 37 or less. I have. Furthermore, a dielectric containing calcium, strontium, and barium zirconate as a main component has excellent characteristics in a microwave frequency band, but has a defect that the dielectric constant is as low as 34.

At present, there is no dielectric that can maintain a high dielectric constant in a strongly reducing atmosphere.

(Object of the Invention) It is an object of the present invention to provide a dielectric porcelain composition having a dielectric constant of 65 or more, which has excellent durability even in a strongly reducing atmosphere and is capable of processing such as Mo-Mn metallization. And

(Means for Solving the Problems) As a result of studying the above problems, the present inventor has found that by adding an appropriate amount of barium titanate to zirconate of calcium and / or barium,
It has been found that porcelain having high reduction resistance and high dielectric constant can be obtained.

The composition of the dielectric ceramic composition of the present invention is represented by the following formula (1) x (Ca _y Ba _1-y ) ZrO _3. (1-x) BaTiO ₃ ‥‥ (1) , Y is 0.6 ≦ x ≦ 0.95, 0 ≦ y ≦ 1.
0, especially set in the range of 0.6 ≦ x ≦ 0.9.

Examples of porcelain excellent in reduction resistance include porcelain made of CaZrO ₃ , BaZrO ₃ , or a combination thereof. These porcelains have a low dielectric constant of about 33 to 55. According to the present invention,
By adding BaTiO ₃ to this porcelain, the dielectric constant can be significantly improved without impairing the reduction resistance. When the amount of BaTiO ₃ is limited to the above range, the effect of improving the dielectric constant by adding BaTiO ₃ is not exhibited when the value of x is larger than 0.95, and when the value of x is smaller than 0.6, the reduction resistance is reduced and M
This is because the insulation resistance after o-Mn metallization or metallization with an active metal is as low as 3 × 10 ¹⁰ Ω · cm, which is insufficient for the characteristics as a substrate.

In addition, as a metal component of zirconate, Ca or Ba
And Ca may be partially substituted with Sr.

In preparing porcelain can be made by known methods, oxides of the respective metal elements as raw material powder, carbonates, using nitrate, e.g., calcined at 1100 to 1250 ° C., once CaZrO ₃ , SrZrO ₃ , BaZrO ₃ , BaTiO ₃ can be obtained by preparing a powder, mixing a suitable amount of these powders by a known molding method, and then firing in an oxidizing atmosphere at 1400 to 1550 ° C. .

When the above-mentioned dielectric porcelain is applied to a substrate, a metallized metal paste of, for example, W, Mo, Mo-Mn is applied to the surface of the porcelain by a screen printing method or the like according to a known method, or Ti, TiH ₂ , forming a metal layer on the surface of the dielectric by heat treatment of the metal layer by the active metallization method such as Zr after formation, in forming gas (H ₂ -N ₂₎ atmosphere or in an inert atmosphere at 1000 to 1300 ° C. can do.

At this time, the porcelain composition of the present invention can be used as a high-permittivity substrate without a decrease in the dielectric properties of the porcelain itself, especially the insulation resistance, even when treated in a reducing atmosphere.

 Hereinafter, the present invention will be described with reference to the following examples.

(Example) CaCO ₃ , SrCO ₃ , BaCO ₃ , ZrO ₂ , and TiO ₂ were used as raw material powders, calcined at 1100 to 1250 ° C., and CaZrO ₃ , SrZrO ₃ , Ba
A calcined powder of ZrO ₃ and BaTiO ₃ was obtained.

These calcined powders were weighed and mixed so as to have the composition shown in Table 1, and after molding, calcined in the air at 1400 to 1550 ° C for 2 hours.
A disk-shaped porcelain having a diameter of 16 mm and a thickness of 2 mm was obtained.

In-Ga was applied to both sides of the obtained porcelain to form a measurement electrode, and the capacitance of the sample capacitor was measured with an LCR meter to determine the dielectric constant (εr).
The insulation resistance (R) was measured from the wetting current after charging for 1 minute with DC.

On the other hand, Mo-Mn paste was applied to both sides of
00 ° C. of forming gas _{(H 2 12.5%, N 2} 87.5%) was heat treated in an atmosphere to form a Mo-Mn metallized metal film of 2~10μm thickness. Using this metallized metal layer as an electrode, the dielectric constant and insulation resistance were measured in the same manner as described above.

 The results are shown in Table 1.

According to Table 1, Samples No. 5 and No. 6 where the x value is less than 0.6
In this case, the insulation resistance after metallization is as small as 3 × 10 ⁹ Ω · cm. By setting the x value to 0.6 or more, a decrease in insulation resistance after metallization can be suppressed. All of the samples of the present invention achieved a dielectric constant of 65 or more and an insulation resistance after metallization of 3 × 10 ¹² Ω · cm or more.

(Effects of the Invention) As described in detail above, the dielectric porcelain composition of the present invention has excellent reduction resistance. Therefore, when the surface of the porcelain is metallized with an active metal such as Mo-Mn or Ti. No degradation of insulation resistance and high dielectric constant even under strong reducing atmosphere, it can be applied to various substrate materials, such as confidential sealed porcelain substrate with capacitor function for noise prevention used in microwave oven magnetron Becomes

Claims (1)

(57) [Claims] 1. A dielectric ceramic composition having a composition formula of x (Ca _y Ba _1-y ) ZrO _3. (1-x) BaTiO _{3 wherein} 0.6 ≦ x ≦ 0.95 0 ≦ y ≦ 1.0.