JPH09165255A - Colored alumina sintered product and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a colored alumina sintered product having excellent electric characteristics for circuit substrates and LSI packages in high frequency regions and exhibiting a back-based color. SOLUTION: A molded product comprising Nb or a Nb compound in an amount of 0.05-5wt.% converted to their oxides, Cr or a Cr compound in an amount of 0-5wt.% converted to their oxides and Al2 O3 in the remaining amount is sintered in a reducing atmosphere to obtain the sintered product comprising Nb in an amount of 0.05-5wt.% converted to the oxide, Cr in an amount of 0-5wt.%, and Al2 O3 and inevitable impurities in the remaining amount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention particularly relates to a colored alumina sintered body suitable for an insulating substrate such as a multilayer wiring substrate or a semiconductor mounting package used in a high frequency region, and a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, the properties required of ceramic materials are thermal properties such as heat resistance, mechanical properties such as strength,
It has chemical properties such as corrosion resistance and electromagnetic properties such as conductivity. In particular, an alumina-based sintered body is often used as an insulating substrate in a wiring substrate or a package for housing a semiconductor element. This alumina-based sintered body is obtained by adding a proper amount of MgO, SiO ₂ , CaO or the like as a sintering aid component to Al ₂ O _{3 and} sintering it.

In recent years, there has been a demand for a substrate material which has a small loss at high frequencies due to the speeding up of LSIs and the increase in the amount of information in the communication field. High-purity alumina has been conventionally used for such applications. Although high-purity Al ₂ O ₃ can be utilized to electrically superior characteristics possessed by the Al ₂ O ₃ since the additive is small as it is, since the Al ₂ O ₃ is a white high-purity Al ₂ O ₃ sintered body also It has a white color.

On the other hand, black alumina is required for electronic parts, semiconductor manufacturing parts, various measuring devices and the like. This means that a small amount of dust has a great influence on the accuracy and performance of these parts, but when it is black, the existence of these dusts can be found quickly, and when a part is worn or damaged, its location Because it can be easily identified. In addition, contrast is required to optically identify the wire bonding position during package manufacturing. In addition, black has a merit that it has a profound feeling and is excellent in aesthetics.

Among such black ceramics, a black alumina-based sintered body is conventionally composed mainly of Al ₂ O ₃ and pigments such as WO ₃ and MoO ₃ are added.
It was colored by firing at a temperature of 00 ° C. or higher.

[0006]

However, according to the conventional black alumina sintered body, when WO ₃ or MoO _{3 is} added as a coloring agent, the physical properties at high temperature and the electrical characteristics may deteriorate. Especially, in the high frequency region of 1 GHz or more, the dielectric loss increases, and the electrical, mechanical and thermal characteristics peculiar to the alumina sintered body are impaired.

Therefore, the present invention has excellent electric characteristics as a circuit board or an LSI package in a high frequency region,
Moreover, it is an object of the present invention to obtain a colored alumina-based sintered body exhibiting a color based on black.

[0008]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that
In a sintered body in which a Cr compound or a Cr compound and an Nb compound are compounded, and the balance is substantially Al ₂ O ₃ ,
While exhibiting a dark-colored color with excellent aesthetics, it is possible to reduce the dielectric loss in the high frequency range compared to the original dielectric loss of alumina, and to improve the mechanical properties compared to conventional high-purity alumina sintered bodies. Heading The present invention has been reached.

That is, the colored alumina sintered body of the present invention is
Nb is contained in an amount of 0.05 to 5% by weight in terms of oxide, Cr is contained in a ratio of 0 to 5% by weight in terms of oxide, and the balance is composed of Al ₂ O ₃ and unavoidable impurities. As a manufacturing method thereof, molding containing Nb or Nb compound in an amount of 0.05 to 5% by weight as oxide, Cr or Cr compound in an amount of 0 to 5% by weight as oxide, and the balance being Al ₂ O _3. The body is fired in a reducing atmosphere, preferably in an atmosphere containing at least hydrogen at 1200 to 1650 ° C.

[0010]

The colored alumina-based sintered body of the present invention is a high-purity alumina-based sintered body that does not contain SiO ₂ , CaO, MgO, etc., which have been conventionally used as sintering aids. 0.05 to 5% by weight of Nb in terms of oxide
By adding and containing it in a proportion of, the dielectric loss is reduced in the high frequency region as compared with the conventional high-purity alumina sintered body,
The strength can be increased, and at the same time, it can be colored in a blackish color full of weight. Further, when Cr is contained in an amount of 5% by weight or less in terms of oxide, it can be colored more red, and the tint can be adjusted by the combination with the Nb compound without affecting the characteristics. You can

As a result, it can be effectively used as an insulating substrate for a wiring board used in a high frequency region of 1 GHz or more, a semiconductor package material for high-speed processing LSI, and a high-frequency circuit board.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION According to the alumina-based sintered body of the present invention, the Nb compound is 0.05 to 5 wt% in terms of oxide, particularly 0.1 to 2.0 wt%, and the Cr compound is oxide. Converted to 0
.About.5 wt%, especially 0.5 to 2.0 wt%, with the balance consisting of Al ₂ O ₃ and unavoidable impurities. This is because the Nb compound is 0.1% by weight in terms of oxide.
If it is less than 5% by weight, the black coloring effect and the effect of reducing the dielectric loss are small. This is because it causes problems such as pollution.

The Cr compound need not be added when the Nb compound is added. However, if the Cr compound is added, the color of the sintered body can be controlled to a reddish color.
When the oxide conversion amount of r is more than 5% by weight, the sinterability is deteriorated and the insulation resistance is lowered, which is not suitable for use as an insulating substrate.

Magnesium oxide, silicon oxide, calcium oxide and the like, which are generally added as a sintering aid to alumina, may significantly increase the loss at high frequencies. Therefore, in the alumina-based sintered body of the present invention, these sintering aids and the like are not substantially contained, and the Nb compound and Cr
Components other than the compound are Al ₂ O ₃ and unavoidable impurities. This unavoidable impurity is an unavoidable impurity contained in the starting material or a component inevitably mixed during the manufacturing process, and the total amount of these unavoidable impurities is preferably 0.2% by weight or less.

Further, the Al ₂ O ₃ powder to be used preferably has a purity of 99.9% or more in order to obtain good high frequency characteristics. It is preferably 0 μm or less.

The colored alumina sintered body according to the present invention is
With respect to Al ₂ O ₃ powder, Nb powder or Nb compound is added in an amount of 0.05 to 5% by weight in terms of oxide, and Cr powder or Cr compound is added in an amount of 0 to 5% by weight in terms of oxide. . As the Nb compound and Cr compound, oxides, carbonates, nitrates, acetates, hydroxides and the like that can be converted into the above oxides by the firing step, as well as carbides and nitrides may be used.

After adding an organic binder and the like to the above composition and mixing them sufficiently, any desired molding means such as a mold pressing method, a cold isostatic pressing method, an extrusion molding method, a doctor blade method and the like can be used. Is shaped into a shape, and is preferably heat-treated in an atmosphere containing water vapor to remove the organic binder, and then fired.

Firing is performed in a reducing atmosphere from 1200 to 165.
By firing at a temperature of 0 ° C. for about 0.5 to 24 hours, a dense and colored sintered body having a relative density ratio of 97% or more can be obtained.

When only the Nb compound is added, the atmosphere during firing becomes white in an oxidizing atmosphere such as the air and does not show black. In order to show a black color, it is effective to mix several% or more of hydrogen into the atmosphere during firing. The darker the hydrogen concentration, the darker the black color. As the gas other than hydrogen, an inert gas or nitrogen is used. It is also possible to introduce a known amount of water vapor to accelerate the decomposition of the binder.

[0020]

EXAMPLE As a raw material powder, Al ₂ O ₃ powder having a purity of 99.9% and an average particle size of 2 μm was added, and N was added as an additive component.
b ₂ O ₅ , Cr ₂ O ₃ and other Nb compounds, Cr
The compound powders were weighed so that the ratios shown in Table 1 were obtained and then mixed by a ball mill.

After this was dried and granulated, 1000 kg / cm ²
After press-molding under the pressure of, it was fired under the conditions shown in Table 1.

The color tone of the obtained sintered body was examined, and a bending test piece was cut out from the sintered body according to JIS R160.
The three-point bending strength according to 1 and the relative density were calculated by the Archimedes method. In addition, each sample was processed into a cylindrical shape with a diameter of 15 mm and a thickness of 7.5 mm, both end surfaces were short-circuited with copper plates, and the measurement frequency was 8.5 GH by the dielectric cylindrical resonance method.
In z, the relative permittivity and the dielectric loss tangent were measured under the TE ₀₁₁ mode resonance characteristic condition. Table 1 shows the results.

[0023]

[Table 1]

As is clear from the results shown in Table 1, Al ₂
Sample No. 1 containing only O ₃ had white color, had voids, had a dielectric loss of 15 × 10 ⁻⁴ and a bending strength of 300 MPa. To this, WO ₃ or MoO ₃ was added as a sintering aid and a colorant. Also in the added samples No. 2 and 3, the dielectric loss was large.

On the other hand, according to the present invention, as Nb is added, blackening progresses and the dielectric loss is 10 × 1.
It was reduced to 0 ^-4 or less, particularly 1 × 10 ^-4 or less, and the bending strength was 400 MPa or more, and the maximum was 600 MPa.
However, sample N whose Nb content exceeds 5% by weight in terms of oxide
At o.9, the dielectric loss increased to 30 × 10 ⁻⁴ .

Further, as shown in Sample Nos. 9 to 15, the color became reddish with the addition of Cr, but the content of Cr in the oxide was over 5% by weight. In Nos. 13 and 17, the dielectric loss decreased and the bending strength also decreased.

[0027]

As described in detail above, the colored alumina-based sintered body of the present invention has a lower dielectric loss and higher strength than the conventional high-purity alumina-based sintered body in the high frequency range. At the same time, the tint can be adjusted in the range of black to purple.

As a result, it can be effectively used as an insulating substrate for a wiring board used in a high frequency region of 1 GHz or more, a semiconductor package material for high-speed processing LSI, and a high-frequency circuit board.

Claims (2)

[Claims] 1. Nb of 0.05 to 5% by weight in terms of oxide,
A colored alumina sintered body, which contains Cr in an amount of 0 to 5% by weight in terms of oxide, and the balance is Al ₂ O ₃ and inevitable impurities. 2. Nb or an Nb compound in terms of oxide of 0.
Coloring characterized by firing a molded body containing 05 to 5% by weight, Cr or a Cr compound in an amount of 0 to 5% by weight in terms of oxide, and the balance being Al ₂ O ₃ in a reducing atmosphere. A method for manufacturing an alumina-based sintered body.