JPH054857A - Production of ceramics base - Google Patents

Abstract

PURPOSE:To prevent aggregation of ceramics powder and to produce a ceramics base having surface smoothness. CONSTITUTION:Ceramics powder is put in a liquid and provided with ultrasonic vibration to dissociate aggregation of ceramics powder. Methyl cellulose is added to the liquid, dissolved and heated to gelatinize the methyl cellulose. Then the liquid is kneaded to prepare body, which is molded and burnt to produce a ceramics base. Even if fine particles of ceramics powder having <=1mum particle size is used, aggregation of ceramics powder is dissociated by ultrasonic vibration and reaggregation of ceramics powder can be prevented by coating the surface of the ceramic powder with methyl cellulose gel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic substrate which is processed into a printed wiring board or the like.

[0002]

2. Description of the Related Art Ceramic substrates are provided as substrates for printed wiring boards and substrates for mounting various electronic elements.
This ceramic substrate is being widely used because it has excellent performance in electrical characteristics and heat resistance.
In such a ceramic substrate, ceramic powder such as alumina is mixed with a sintering aid, and methyl cellulose and water as an organic binder are further mixed, and the mixture is kneaded with a roll mill or the like to form a cup clay. Then, the clay is extruded by a vacuum forming machine or the like to form a sheet, which is dried and then baked. When a ceramic substrate is used as a circuit board such as a printed wiring board, it is required that the structure is dense and the surface is highly smooth in order to cope with recent fine pattern circuit formation and high-density mounting. ,
As a result, fine particles having a particle size of 1 μm or less are used as the ceramic powder.

[0003]

However, when the fine ceramic powder is used as described above, the particles agglomerate to increase the apparent particle size of the ceramic powder, which is called Fisher's eye on the surface of the ceramic substrate. Diameter 10
There was a problem that ceramic aggregates having a size of about 0 μm remained, and the substrate surface became uneven, so that it could not be used as a circuit board.

The present invention has been made in view of the above points, and an object of the present invention is to provide a method of manufacturing a ceramic substrate which can prevent the agglomeration of ceramic powder and obtain a ceramic substrate having a smooth surface. It is a thing.

[0005]

According to the method for manufacturing a ceramic substrate of the present invention, the agglomeration of the ceramic powder is dissociated by introducing the ceramic powder into a liquid and applying ultrasonic vibration to the liquid. The method is characterized in that methylcellulose is charged and dissolved, and then heated to gelate the methylcellulose, which is then kneaded to form a cup clay, and the cup clay is molded and fired.

The present invention will be described in detail below. As the ceramic powder, powder of alumina, ferrite, zirconia or the like can be used, and in the present invention, fine powder having a particle size of 1 μm or less is used.
Further, powders of talc, magnesia, calcia, silica and the like are used as a sintering aid together with the ceramic powder.

First, the ceramic powder and the sintering aid are added to a liquid so as to have a concentration of about 10 to 20% by weight and mixed. Water is preferred as this liquid. The mixing ratio of the ceramic powder and the sintering aid is 90:10 by weight.
It is preferable to set in the range of ˜99: 1. Next, ultrasonic waves are applied to this liquid to apply ultrasonic vibrations to dissociate the agglomeration of the fine particles of the ceramic powder and separate the fine particles. The ultrasonic wave at this time is 40 to 100 kH
The z frequency is preferable, and the time for applying ultrasonic vibration must be at least 1 hour or more.

After the ultrasonic vibration is applied in this way to dissociate and loosen the agglomeration of the ceramic powder, methylcellulose powder used as an organic binder is added to the liquid obtained by mixing the ceramic powder and the sintering aid. . Methyl cellulose is added while applying ultrasonic waves to the liquid, and methyl cellulose is added and dissolved so that its concentration becomes 1 to 2% by weight. Next, the liquid in which methyl cellulose is thus dissolved is heated to raise the temperature to 80 ° C. or higher. Methylcellulose solution is 80
It gels at a temperature of ℃ or more, and after the gelation in this way, heating is continued and the liquid is boiled until it becomes clay-like. By gelling methyl cellulose in this way, the fine particles of the ceramic powder are coated on the surface with the methyl cellulose gel, and it is possible to prevent the fine particles of the ceramic powder from re-aggregating.

Next, the clay-like material thus obtained is kneaded with a kneader such as a three-roll mill, and kneading is performed while adding a molding aid such as glycerin, if necessary, to prepare a clay. To do. At this time, it is preferable to carry out kneading while adjusting the water content so that the water content is 15 to 25 wt% by spraying water with a sprayer or the like. A ceramic substrate can be obtained by subjecting this clay to extrusion molding to a predetermined thickness with a vacuum extrusion molding machine or the like, drying, punching to a predetermined size, and then firing. The firing conditions are not particularly limited, but the temperature rising rate is set to 100 to 200 ° C./h and 1550 to 165.
It is preferable to perform firing at a temperature of about 0 ° C. for 1 to 4 hours.

[0010]

Operation: Since the agglomeration of the ceramic powder is dissociated by introducing the ceramic powder into a liquid and applying ultrasonic vibration, even if a fine ceramic powder having a particle size of 1 μm or less is used, It is possible to manufacture a ceramic substrate without agglomeration of. In addition, since methyl cellulose is put into this liquid and dissolved and then heated to gel the methyl cellulose, the surface of the ceramic powder is coated with methyl cellulose gel, and the particles of the ceramic powder are re-aggregated. Can be prevented.

[0011]

EXAMPLES Next, the present invention will be specifically described by way of examples. Example Alumina powder having a particle size of 0.4 μm and talc powder as a sintering aid were mixed at a weight ratio of 96: 4, and this was added to water so that the concentration became 10% by weight. Next, an ultrasonic oscillator was put in this liquid, and ultrasonic vibration of 60 kHz was applied for 24 hours. Next, while continuing the oscillation of ultrasonic waves, methylcellulose powder was added to this solution at a concentration of 2% by weight, and further mixed for 1 hour with a vibration mill.
After mixing in this way, the mixed solution was taken out from the vibration mill and heated to a temperature of 90 ° C. to gel the methyl cellulose in the mixed solution. A clay-like mixed solution obtained by gelling and boiling down methylcellulose was kneaded with a three-roll mill, and 3% by weight of glycerin as a molding aid was added and further kneaded to prepare a clay. The thus-prepared clay was extruded by a vacuum extruder to form a sheet having a thickness of 0.8 mm, and the sheet was fired at 1600 ° C. for 2 hours to obtain a ceramic substrate.

Comparative Example 9 Alumina powder having a particle size of 0.4 μm and talc powder were mixed with each other.
Mix in a weight ratio of 6: 4 and mix this with water to a concentration of 10% by weight.
Was added until. This was wet mixed with a ball mill for about 1 hour to disperse the alumina powder and the talc powder.
Next, methylcellulose was added to this mixed solution so that the concentration would be 2% by weight, and mixed by a ball mill for 1 hour. After that, a ceramic substrate was obtained in the same manner as in Examples 1 to 3.

When the surfaces of the ceramic substrates obtained in Examples and Comparative Examples as described above were inspected, 20 to 30 Fisher's eyes due to agglomeration of the ceramic powder were observed per 2 cm square in the Comparative Example. However, in the example, the number was reduced to 2 to 3 per 2 cm square. The maximum roughness R _max of the surface of the ceramic substrate was 2 μm in the comparative example, but was 1 μm in the example. As described above, in the ceramic substrate of the example, the agglomeration of the ceramic powder was hardly seen, and the surface smoothness was very high.

[0014]

As described above, according to the present invention, the agglomeration of the ceramic powder is dissociated by introducing the ceramic powder into a liquid and applying ultrasonic vibration, and then methylcellulose is introduced into this liquid and dissolved. After that, the methyl cellulose was gelated by heating after that, and this was kneaded to prepare the clay, so that even if a fine ceramic powder with a particle size of 1 μm or less is used, the ceramic powder is agglomerated by ultrasonic vibration. Can be dissociated to prevent the agglomeration of particles, and the surface of the ceramic powder can be coated with a gel of methylcellulose to prevent the particles of the ceramic powder from agglomerating again. It is possible to obtain a ceramic substrate having a smooth surface.

Claims (1)

Claim: What is claimed is: 1. A ceramic powder is charged into a liquid and ultrasonic vibration is applied to dissociate the agglomeration of the ceramic powder, and then methylcellulose is charged into the liquid and dissolved, and then heated. And gelling the methylcellulose, kneading the mixture to form a clay, and molding and baking the clay to produce a ceramic substrate.