JPH054853A - 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 blended with a dispersant and a plasticizer, dried and powdered to prepare ceramics powder coated with the dispersant and the plasticizer. The coated powder is kneaded with an aqueous solution of methyl cellulose to prepare body. The body is molded and burnt to give a ceramics base. Since the particles of the ceramics powder are coated with dispersant and the plasticizer, when the ceramics powder is dispersed in preparing body by kneading the ceramics powder with methyl cellulose, the particles of the ceramics powder can be prevented from aggregating by action of the dispersant applied to the periphery.

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.
For such a ceramic substrate, ceramic powder such as alumina is mixed with methyl cellulose as a binder, and the mixture is kneaded by a roll mill or the like to prepare a clay, which is then extruded by a vacuum forming machine or the like. Is manufactured into a sheet shape, and the molded green sheet is dried and then fired. When a ceramic substrate is used as a circuit substrate, it is required that the structure be dense and the surface be highly smooth in order to cope with the recent fine pattern circuit formation and high-density mounting. The particle size of the body is 1 μm
The following fine particles have been used.

[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, and when the green sheet is molded, the diameter is about 100 μm. The problem is that agglomerates of large-sized ceramic powder are generated, and even after firing, ceramic agglomerates called Fisher's eyes remain on the surface of the ceramic substrate, causing irregularities on the substrate surface and making it impossible to use as a circuit board. was there.

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]

A method of manufacturing a ceramic substrate according to the present invention comprises mixing a ceramic powder with a dispersant and a plasticizer, and drying and powdering the ceramic powder to obtain a dispersant and a plasticizer. Is prepared, and the coated powder is kneaded with an aqueous solution of methylcellulose to prepare a clay, and the 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. First, a water-soluble dispersant and a plasticizer are mixed with the ceramic powder in an aqueous solution state. As the dispersant, a polycarboxylic acid-based dispersant such as a polycarboxylic acid ammonium salt is used. For example, those provided as "Poise 532A" or "Poise 530" by Kao Soap Co., Ltd., or Chukyo Yushi Co., Ltd. Those provided as "Selna D-305" and "Selna D-735", those provided by San Nopco as "SN Dispersant 5468", "Aron A-30SL" and "Aron" by Toagosei Co., Ltd. A-6
114 ”can be used. As the plasticizer, glycerin, ethylene glycol, other uniloop (trade name of NOF CORPORATION), water-soluble akrin, or the like can be used. The mixing ratio of ceramic powder, dispersant and plasticizer is 100: 0.5 by weight.
It is preferable to set it in the range of 1: 1 to 1-2, and the mixture thus prepared to prepare a slurry is dried and powdered into granules. This powder is prepared as a coating powder in which particles of ceramic powder are coated with a dispersant and a plasticizer, and the particle size is preferably adjusted to about 10 to 150 μm.

On the other hand, methylcellulose used as a binder is dissolved in water at a concentration of about 1 to 2% by weight, and if necessary, the undissolved portion of methylcellulose is removed, and then the aqueous solution of methylcellulose is heated to 80 ° C. or higher. Heat to temperature. An aqueous solution of methylcellulose gels when heated to a temperature of 80 ° C or higher. The methylcellulose gel and, if necessary, a plasticizer and water are added to the coated powder prepared as described above and kneaded to prepare a clay. After that, the clay is extruded into a predetermined thickness with a vacuum extrusion molding machine or the like, dried, punched into a predetermined size, and then fired to obtain a ceramic substrate. The firing conditions are not particularly limited, but it is preferable to set the rate of temperature rise to 100 to 200 ° C./h and perform firing at a temperature of about 1550 to 1650 ° C. for 1 to 4 hours.

[0008]

[Function] The ceramic powder is coated with the dispersant and the plasticizer by mixing the ceramic powder with the dispersant and the plasticizer and drying and pulverizing the mixture. The particles of the powder are coated with a dispersant and a plasticizer, and when the ceramic powder is dispersed when kneading the ceramic powder with methyl cellulose to form a clay, the action of the dispersant coated around Thus, it is possible to prevent the particles of the ceramic powder from aggregating, and it is possible to manufacture a ceramic substrate without agglomeration of the particles, even if the fine ceramic powder having a particle diameter of 1 μm or less is used.

[0009]

EXAMPLES Next, the present invention will be specifically described by way of examples. Example Alumina powder having a particle size of 0.4 μm, ammonium polycarboxylate as a dispersant, and glycerin as a plasticizer were blended in a weight ratio of 100: 0.5: 1, and mixed in a ball mill. To prepare a slurry. Next, this slurry was dried with a drum dryer to a water content of 3% by weight or less and pulverized to obtain an average particle size of 8
A coated powder of 0 μm was obtained. On the other hand, methylcellulose was added to water to a concentration of 2% by weight and dissolved,
Remove undissolved content by filtering using a filter press,
The filtrate was heated to 90 ° C. to prepare a methylcellulose gel having a water content of 30% by weight. The methylcellulose gel obtained in (1), glycerin as a plasticizer and water were added to the coated powder obtained in (1) and mixed with a super mixer. At this time, the mixing ratio of the coating powder, methyl cellulose gel (solid content conversion), and glycerin was set to 101: 5: 10, and the mixing ratio of water was set to 16 including the water content in the methyl cellulose gel. After mixing in this manner, water was sprayed and kneaded with a three-roll mill while adjusting the water content to 20 ± 5% by weight to prepare a cup clay. The clay thus formed was extruded by a vacuum extruder to form a green sheet having a thickness of 0.8 mm, and the green sheet was fired at 1600 ° C. for 2 hours to obtain a ceramic substrate.

Comparative Example Methylcellulose was added to water so as to have a concentration of 2% by weight to dissolve it, and the undissolved portion was removed by filtration using a filter press, and the filtrate was heated to 90 ° C. to obtain a water content. Of 30% by weight of methylcellulose gel was prepared. Ammonium polycarboxylate, glycerin, and the methylcellulose gel obtained in (4) were added to alumina powder having a particle size of 0.4 μm, and water was added, and mixed with a super mixer. At this time, alumina powder, ammonium polycarboxylate, glycerin, and methylcellulose gel (solid content conversion)
The compounding ratio of was set to 101: 0.5: 10: 5, and the compounding ratio of water was set to 16 including the water content in the methylcellulose gel. This mixture was kneaded with a three-roll mill to prepare a cup soil. After that, a ceramic substrate was obtained in the same manner as in the example.

When the surfaces of the green sheets obtained in Examples and Comparative Examples as described above were observed, the number of aggregates of alumina powder was 300 or more in the Comparative Example, but in the Example. Reduced to 5-20. Further, the surface roughness Ra of the ceramic substrate obtained in the example was 0.2, and the smoothness was very high.

[0012]

As described above, the present invention provides a coated powder obtained by coating a ceramic powder with a dispersant and a plasticizer by mixing the ceramic powder with a dispersant and the plasticizer and drying and powdering. The prepared powder was kneaded with an aqueous solution of methylcellulose to prepare a clay, and the clay was molded and fired, so that the particles of the ceramic powder were coated with the dispersant and the plasticizer. In order to disperse the ceramic powder when kneading the ceramic powder with methyl cellulose to form the clay, it is possible to prevent the particles of the ceramic powder from agglomerating due to the action of the dispersant coated around the ceramic powder. Even if a fine ceramic powder having a particle diameter of 1 μm or less is used, it is possible to produce a ceramic substrate having a smooth surface without agglomeration of the particles.

Claims (1)

Claim: What is claimed is: 1. A ceramic powder coated with a dispersant and a plasticizer is prepared by mixing a ceramic powder with a dispersant and a plasticizer and drying and pulverizing the mixture. A method for producing a ceramic substrate, comprising: kneading the coated powder with an aqueous solution of methylcellulose to prepare a cup clay, and molding and firing the cup clay.