JPH054866A - Ceramic composition - Google Patents

Abstract

PURPOSE:To obtain the title composition improved in the bond strength between metallizing metal and the ceramic therefrom by incorporating a ceramic composition predominant in mullite with each specified amount of yttria as sintering auxiliary and borosilicate glass. CONSTITUTION:For example, a synthetic mullite raw material is incorporated with (A) 2-4wt.%, on an outer basis, of yttria and (B) 2.0-10wt.%, on an outer basis, of borosilicate glass. The resulting raw material is then incorporated with an organic binder, plasticizer and solvent followed by grinding and mixing in a ball mill into a slurry, from which a tape-shaped ceramic green sheet is formed through doctor blade technique. This sheet is subjected to raw processing and cut into chips, which are then coated with a metallic paste such as of W or Mo and fired in a wet hydrogen-nitrogen mixed gas. Thereby, borosilicate glass will be intruded as liquid component into mullite's inner pores, leading to increase in the bond strength between the metallizing metal and the resultant ceramic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a porcelain composition containing mullite as a main component, which is used as a material for a substrate for electronic circuits.

[0002]

_2. Description of the Related Art Mullite having a chemical composition represented by 3Al ₂ O ₃ .2SiO ₂ has a lower dielectric constant than alumina (Al ₂ O ₃ ) and has a thermal expansion coefficient close to that of silicon. Is being watched as.

While mullite has excellent properties as described above, it has a drawback that it is difficult to sinter. Therefore, JP-A-63-236758 and JP-A-64-23599
The publication discloses that magnesia (MgO), calcia (CaO) or yttria (Y ₂ O ₃ ) is added as a sintering aid.

[0004]

Since the sintering temperature can be lowered by adding the sintering aid as described above, it is possible to perform simultaneous firing with a metallized metal such as tungsten or molybdenum. However, mullite has almost no liquid phase component and many internal pores. Therefore, even if sintering is promoted by adding a sintering aid, the bonding strength between the metallized metal and the ceramic when metallizing is not improved.

[0005]

In order to solve the above problems, the present invention adds yttria, magnesia or calcia as a sintering aid to a porcelain composition containing mullite as a main component, and an external ratio of 2.0 wt. % -10 wt% borosilicate glass was added.

[0006]

When the borosilicate glass is added, the borosilicate glass penetrates into the inner pores of the mullite as a liquid phase component to enhance the bonding strength between the metallized metal and the ceramic.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings. Here, FIG. 1 is a block diagram showing a process for producing a mullite substrate for testing. First, yttria is added to the synthetic mullite raw material at an external ratio (the synthetic mullite is 100) in an amount of 2 to 4 wt% (2 wt% steps). Then, borosilicate glass was also added in an external ratio of 0 to 10 wt% (2 wt% in increments) to prepare raw materials.

Then, an organic binder, a plasticizer and a solvent are added to the above raw materials and the mixture is crushed and mixed by a ball mill to form a slurry, and a tape-shaped ceramic green sheet is formed from this slurry by a doctor blade method.

Then, the ceramic green sheet was subjected to raw processing, cut into chips, and predetermined chips were baked as they were, and then the strength and the coefficient of thermal expansion were measured.

For other chips, a metal paste such as tungsten or molybdenum was applied and fired in a wet hydrogen / nitrogen mixed gas, and the metallization strength and dielectric constant of the obtained mullite substrate were measured.

The structure of the mullite substrate obtained as described above is shown in FIG. 2, of which FIG. 2 (a) shows the structure of the mullite substrate according to the present invention to which borosilicate glass is added. FIG. 2B is an enlarged cross-sectional view showing the structure of a conventional mullite substrate to which no borosilicate glass is added. From these figures, the conventional mullite substrate has many pores inside, but the present invention It can be seen that most of the pores of the mullite substrate according to (1) are filled with borosilicate glass or are small.

The following (Table 1) is a sintering aid (Y ₂ O ₃ )
And the metallized strength, strength (strength as a substrate), dielectric constant and thermal expansion coefficient of the product of the present invention and the conventional product in which the ratio of addition of borosilicate glass (wt% in external ratio) is variously changed. ..

[0013]

[Table 1]

[0014]

As is clear from the above (Table 1) and FIG. 2 (a), the present invention adds yttria, magnesia or calcia as a sintering aid to a porcelain composition mainly containing mullite. , 2.0wt% to 10w in external ratio
Since t% borosilicate glass was added, this borosilicate glass penetrated into the inner pores of mullite as a liquid phase component, and the bonding strength between the metallized metal and the ceramic was 2.8 to 3.5 kg / mm ^{2 in the} past. It is 5.0k
It can be increased to g / mm ² or more.

The strength of the substrate itself can be 18 kg / mm ² or more, the dielectric constant can be 7.6 or less, and the thermal expansion coefficient can be 4.8 × 10 ⁶ / ° C. or less.

[Brief description of drawings]

FIG. 1 is a block diagram showing a process of producing a mullite substrate for testing from a porcelain composition according to the present invention and a conventional porcelain composition.

FIG. 2 is an enlarged cross-sectional view of the structures of a mullite substrate manufactured from a porcelain composition according to the present invention and a mullite substrate manufactured from a conventional porcelain composition.

Claims (1)

Claims: 1. A porcelain composition containing mullite as a main component, wherein the porcelain composition is yttria as a sintering aid,
In addition to magnesia or calcia, the external ratio is 2.0 wt% ~
A porcelain composition, to which 10 wt% of borosilicate glass is added.