JPS585207A - Manufacture of ceramic green sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a green ceramic sheet, particularly one having high smoothness and high density.

Furthermore, the present invention relates to a method for producing a ceramic green sheet with fewer defects such as pinholes.

Recently, a wide variety of electronic components using various ceramics are becoming more dense and smaller. In particular, laminated ceramics,
The capacitor is a typical example of such miniaturization. Multilayer ceramic capacitors are produced by printing internal electrodes on raw ceramic sheets, laminating them by thermocompression, cutting them to a predetermined size, and then firing them. Methods for producing green ceramic sheets include extrusion molding, hot rolling, screen printing, and doctor blemishing, but doctor blading is commonly used.

By the way, the ceramic green sheet formed by this doctor blade method has three problems: 1) the surface is not very smooth; even if vacuum-defoamed slurry is used, air bubbles are present inside the sheet; and the wettability of the slurry to the base film is poor. It often has defects such as pinholes and other defects. In the case of laminated ceramic capacitors, internal electrode paste is screen printed on ceramic raw sheets having such defects. However, laminated ceramic capacitors are laminated, thermocompressed, and fired as they are.

Failures often occur due to the defective location.

In order to eliminate these drawbacks, the present invention allows a green ceramic sheet formed by the doctor blade method to pass through a rolling roll (whether cold or hot) without peeling from the base film. Make sure the surface is smooth.

To provide a new method for producing a high-density green ceramic sheet with excellent smoothness by crushing air bubbles, voids, pinholes, etc. and further improving the packing density of ceramic particles compared to the green sheet state. It is an object.

The present invention will be explained below using examples.

First, there is a binder, which is an organic component in the ceramic material.

Add the specified amount of plasticizer and solvent and ball mill.

Mix well using a known mixing method such as a kneader or homogenizer to form a slurry. This slurry is poured onto an organic film, formed into a sheet of a certain thickness using the doctor blade method, and dried to suit the application.

A ceramic green sheet with a constant thickness of 0.02 to 0.1 m is produced. Next, this green sheet is rolled with a calender roll without being peeled off from the base film. The roll may be rolled cold, but if the binder is thermoplastic, hot rolling is more effective.

The ceramic materials used in the method of the present invention are alumina (A403) and magnesia (Mg0) in the case of ceramic substrates.
) In the case of a piezoelectric dielectric material such as forsterite or steatite, ffaTi03PZT or a lead-based piezoelectric material may be used, and in the case of a magnetic material, any ferrite material may be used. Examples of organic binders include polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral,
Examples include vinyl chloride-hynylacetate copolymer, methylcellulose, ethylcellulose, and the like, but from the viewpoint of adhesiveness, polyvinyl butyral, polyvinyl acetate, etc. are preferable. The plasticizer is selected depending on the binder, and phthalate-based, glycol-based, glycerin-based, etc. are used.

The amount of binder and plasticizer is 1 to 1°wt, taking into consideration moldability, workability, densification, and degassing property in the firing process.
% is preferred. As the solvent, water, alcohol, ketone, etc. are used.

The ceramic raw sheet obtained by the method of the present invention is highly smooth and free of defects such as bubbles, voids, and holes.
Because the ceramic particles are densely packed and of high quality, ceramic electronic components manufactured using this green sheet have high performance and high reliability.

The reason why the raw sheet is rolled without being peeled off from the base film is that the base film does not serve as a support for the raw sheet during rolling, but rather that internal electrodes are placed on the raw sheet as in the case of laminated ceramics. If the paste is printed and dried while being supported by the base film, there will be no problem of deformation of the sheet due to drying of the paste solvent, and it has advantages such as continuous screen printing becomes possible. It is.

This will be explained using a more specific example.

As a ceramic material, I Pb (Nb1/2 Fe1
/2) (167(W 1/3 Fe 2/3) 3.0
A composite perovskite dielectric material with a composition of 7.
After pre-baking at 20°C, the product was pulverized in a ball mill. This ceramic powder was dispersed in 34 wt% ethyl cellulose using a homomixer with stirring blades rotating at high speed, and then 5 wt% polyvinyl butyral and 1 wt% butylphthalyl butyl glycolate were added and mixed well to form a slurry. make. This slurry was poured onto a polyester film to produce a 60 μm thick green sheet using a doctor blade method.

Next, this green sheet was rolled through a calender roll at 85° C. while remaining attached to the polyester film. After screen-printing internal electrodes on this rolled raw sheet, the printed raw sheet film is peeled off from the base film,
After punching to a specified size of 10100 x 120 and stacking in a mold.

It was hot pressed at 250 to 9/2 and 110°C. This was cut to obtain individual raw chips of multilayer ceramic capacitors. After removing the binder under the specified conditions.

After firing, the laminated ceramic cap was evaluated for life test. The results are shown in Table 1.

Margin below Table 1 As described above, according to the present invention, it is highly smooth.

A high-density raw ceramic sheet with no defects can be obtained.
It is now possible to provide high performance, highly reliable ceramic electronic components.

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Claims (1)

[Claims] 1. Add organic components such as a binder, a plasticizer, and a solvent to a ceramic material to create a slurry, pour this slurry onto a smooth base film, and use a doctor blade method to produce a raw sheet. After. A method for producing a ceramic green sheet, characterized in that the green sheet is passed through a rolling roll without being peeled off from a base film.