JPH0248901A - Manufacture of ceramic board - Google Patents

Abstract

PURPOSE:To manufacture a ceramic sheet superior in surface smoothness, by a method wherein a multi-layer green sheet comprised of ceramic powder whose mean particle diameter is smaller than that of an intermediate layer is baked on both surfaces of the intermediate layer comprised of the ceramic powder whose mean particle diameter is 0.8-0.3mum. CONSTITUTION:A multi-layer green sheet is formed of an intermediate layer and a top and bottom layers for which ceramic powder whose mean diameter is 0.8-3.0mum and ceramic particles whose mean particle diameter is smaller than that of the intermediate layer are used respectively. Slurry for the top and bottom cast in thickness of about 0.1mm by a molding machine for which a doctor plate is used is dried and then slurry for the intermediate layer is cast to the top in thickness of about 0.8mm for drying, in formation of the green sheet. A ceramic sheet obtained through baking is scarcely warped and superior in surface smoothness.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for manufacturing a ceramic substrate used as an electronic component. This invention relates to a method for manufacturing ceramic substrates with small ridges and the like.

(Conventional technology) Ceramic substrates are used as electronic components.

As the wiring to be formed becomes finer, there is a need for a ceramic substrate with low surface roughness and excellent surface smoothness, and a ceramic substrate with high dimensional accuracy including warpage, ridges, etc. .

For this reason, generally, a load is applied to the fired ceramic substrate and then fired to correct the warpage, waviness, etc. In addition, as a method for reducing warpage, ridges, etc., JP-A-57-15
As shown in Japanese Patent Publication No. 2189, there is a stone method in which pressure is applied to the four corners of a ceramic green sheet (hereinafter referred to as green sheet) to increase the packing density from the inside and then fired, as shown in Japanese Patent Application Laid-Open No. 60-73291. Another method is to stack a weight plate around the periphery of the green sheet and remove the two peripheries after firing.

On the other hand, methods for manufacturing ceramic substrates with low surface roughness and excellent surface smoothness include a method in which fine powder with an average particle size of 1 m or less is generally used, a green sheet is formed and fired, and a sol-gel method.

(Problem to be solved by the invention) However, when trying to manufacture products with excellent surface smoothness using the conventional methods described above, molding and firing are difficult.
Repulsion, ridges, etc. become larger.

At present, when trying to manufacture products with small warps, ridges, etc., the drawback is that the surface smoothness is poor, and it is not possible to satisfy all the conditions.

An object of the present invention is to provide a method for manufacturing a ceramic substrate that satisfies all of the above conditions.

(Means for Solving Problem R) The present invention provides a method for manufacturing a ceramic substrate in which ceramic powder slurry is cast onto a carrier film, dried to form a green sheet, and then fired. is a ceramic substrate that uses ceramic powder with an average particle size of 0.8 to 3.0 μm, and uses ceramic powder with a smaller average particle size in the upper and lower layers than the middle layer to form a multilayer green sheet, which is then fired. and a method for manufacturing a ceramic substrate, in which ceramic powder slurry is cast onto a carrier film, dried to form a green sheet, and then fired, the two one-sided layers have an average particle size of 0.8 to 3. .0μm
The present invention relates to a method for manufacturing a ceramic substrate, in which a multilayer green sheet is formed using a ceramic powder having a smaller average particle size than the above ceramic powder on the other side layer, and then firing.

In the present invention, the average particle size of the ceramic powder used for the intermediate layer or one side layer of the green sheet is 0.8 to 3.0 μm.
If the average particle size is less than 0.8 μm, molding and firing become difficult.

The drawback is that the ridges, ridges, etc. become larger.

If the primary average particle diameter exceeds 3.0 μm, the firing temperature will become too high, resulting in insufficient sintering under normal firing conditions.

On the other hand, the ceramic powder used for the upper and lower layers or the other one side layer is
It is necessary to use a ceramic powder having an average particle size smaller than that of the powder used for the intermediate layer or one side layer, and it is preferable to use a ceramic powder having an average particle size of, for example, 0.3 to 0.7 μm.

In the present invention, a sintering aid may be added as necessary.

(Example) The present invention will be explained in detail below.

Example 1 Alumina powder with an average particle size of 1.7 μm (manufactured by Showa Light Metal)
To 98 parts by weight were added 2 parts by weight of sintering aid powder, 5 parts by weight of Polyvinyl Buteller JV (Okisui Kagaku Co., Ltd.), 2 parts by weight of DOP, and 35 parts by weight of an azeotrope of methanol and trichlorethylene, and mixed in a ball mill for 60 hours. Then, we obtained a slurry for the middle layer. The sintering aid powder is pS 1ozr.
MgO + CaO and A12om in a weight ratio of 60:30
: Mixed in a ratio of 4:6.

It was rapidly cooled in a platinum crucible at a temperature of 1,600°C, and then coarsely crushed and milled with a jet mill to an average particle size of 0.8 μm.
Make sure to use one that has been crushed and classified.

On the other hand, 12 parts by weight of polyvinyl butyral (manufactured by Okisui Kagaku), 5 parts by weight of DOP, and 90 parts by weight of an azeotropic mixture of methanol and trichlorethylene were added to 100 parts by weight of alumina powder with an average particle size of 0.5 μm (manufactured by Showa Light Metal). Add and mix in a ball mill for 60 hours.

I got mud for the upper and lower layers.

Next, the slurry for the upper and lower layers is cast into a thickness of α1m using a doctor blade and dried, and then the slurry for the middle layer is cast on the top surface of the slurry in the same manner as above.
It was cast to a thickness of μm and dried.

On top of Sarak, we cast slurry for the upper and lower layers to a thickness of 0.1 ffll+ using the same method as above and dried it, producing a multilayer green sheet with a total thickness of 1.0 ml.

After that, punch it into a size of 55 x 55 am using a mold.

The ceramic substrate of the present invention was obtained by firing at a temperature of 1.550° C. for 1 hour. When the surface roughness of the obtained nine ceramic substrates was measured, the average roughness was 0.06 μmRa, and the surface roughness was 0.08 rMn or less, which was good.

Comparative Example 1 The slurry for the intermediate layer obtained in Example 1 was cast to a thickness of 1.0 mm using a sheet forming machine using a doctor blade, and dried to obtain a green sheet.

A ceramic substrate was obtained in the same manner as in the example. The average surface roughness of the obtained ceramic substrate was 0.22 μm.
One warpage, which is larger than Ra, was 0.05 mm.

Comparative Example 2 The slurry for the upper and lower layers obtained in Example 1 was cast to a thickness of 0.6 m using a nine-sheet molding machine using a doctor blade, and dried to obtain a green sheet.

Thereafter, a ceramic substrate was obtained in the same manner as in Example 1. The average surface roughness of the obtained ceramic substrate is 0.05 μmR.
It was good with a value of a, but the 9 warpage was extremely large with a value of 1.0I.

Note 1. An attempt was made to obtain a green sheet with a thickness of OI, but many cracks occurred during casting or drying, making it unusable.

(Effects of the Invention) The ceramic substrate obtained by the manufacturing method of the present invention can be easily molded and fired, 2 has excellent surface smoothness, 9 has small warpage, ridges, etc., and is extremely suitable for industrial use. .

Claims (2)

[Claims] 1. In the method for manufacturing ceramic substrates in which ceramic powder slurry is cast onto a carrier film, dried to form a ceramic green sheet, and then fired, the intermediate layer contains a layer with an average particle size of 0.8 to 3.0 μm. A method for manufacturing a ceramic substrate, characterized in that a multilayered ceramic green sheet is formed using ceramic powder, the upper and lower layers are ceramic powders with a smaller average particle size than the middle layer, and then fired. 2. In the method of manufacturing a ceramic substrate, in which ceramic powder slurry is cast onto a carrier film, dried to form a ceramic green sheet, and then fired, one layer has a layer with an average particle size of 0.8 to 3.0 μm. 1. A method for manufacturing a ceramic substrate, which comprises forming a multilayer ceramic green sheet using ceramic powder and using ceramic powder with a smaller average particle size than the above for the other layer on one side, and then firing the sheet.