JPS6029601B2 - Manufacturing method of raw ceramic sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a raw ceramic sheet for firing, and more particularly to a method for manufacturing a raw ceramic sheet for firing, which yields a highly smooth and high-density competitive sheet.

In recent years, electronic components using various types of ceramics have become increasingly popular, and their density and size have rapidly increased.

Conventionally, piezoelectric elements in a predetermined shape according to the application have been supplied by machining such as cutting and polishing a compact or single crystal ingot, but this has led to deterioration of various physical properties due to processing distortion and processing costs. The problem of increasing numbers of people is becoming more and more important. For this reason, it is desired that elements of a desired shape can be supplied at low cost at the same time as firing, in order to simplify the process and mass-produce without the post-process of machining. In general, a method for manufacturing retaining sheets is known, in which a ceramic material is kneaded with a binding substance, molded to produce a green sheet of a certain thickness, punched into a predetermined shape according to the intended use, and then fired. There is.

However, in the composite sheet element after dawning, deformation, warping, cracks, perforations, and non-uniform composition occur due to the shrinkage of the raw sheet during firing, which has a large effect on mechanical properties, electrical properties, etc. There is the problem of

In order to obtain a high-performance, high-density, and highly smooth sintered sheet, not only the firing process but also the properties of the raw sheet are greatly influenced.

To enumerate its various characteristics, it is to increase the density of the raw sheet as much as possible. To achieve this, it is necessary to add as little binder and plasticizer as possible to a ceramic material with a large specific surface area or small particle size, which improves silkenability, and thoroughly mix it with an appropriate amount of solvent to improve the dispersion of the ceramic material. thing. Furthermore, it is necessary that the thickness is uniform, that it has sufficient maneuverability, that punching is easy, and that no processing distortion remains. The selection of binder, plasticizer or solvent has a significant influence on these properties and is the most important point in producing green sheets. Next, it becomes important to consider the resin removal process and firing process for organic components.

One method for producing the above-mentioned raw sheet is to add a binder, a plasticizer, and a solvent to a ceramic material to form a slurry;
The doctor blade method involves pouring this onto a smooth substrate, forming it into a sheet of a certain thickness using a doctor blade, and drying it to obtain a raw sheet.LI consists of a ceramic material, a binder,
This is an extrusion molding method in which a green sheet is obtained by extruding a mixture of a plasticizer and a solvent through a mold opening, and there is also a roll method in which hot roll rolling is performed using a thermosetting resin as a binder as a dry molding method. etc. are known.

Among these methods, the doctor blade method is widely used as a method for obtaining green sheets with extremely excellent smoothness, high density, and almost no forming distortion. Regardless of the method used, the raw sheet after drying generally has a gradient in the packing density of the ceramic material in the thickness direction.

Specifically, the side that contacts the base film during sheet molding (the back surface of the green sheet) tends to have a high density, while the free surface side (the surface of the green sheet) where the solvent is scattered tends to have a low density. When such a green sheet is fired, a phenomenon of warping occurs because the shrinkage rate on the back side of the green sheet with a high packing density is greater than that on the front side of the green sheet with a low packing density.

There are other possible causes of warping of the sintered sheet. Examples include uneven density and thickness in the in-plane direction of the raw sheet, rapid resin removal, and uneven heating during firing, but all of these depend on the performance of the sheet forming machine and firing furnace, and This problem can be avoided by using a high-performance device. However, the difference in the packing density of the ceramic material in the thickness direction of the green sheet described above is difficult to avoid, and this seems to be the main cause of the warping phenomenon. In particular, when a thin raw sheet with a thickness of 0.5 or less is fired, the warpage is significant. To prevent this kind of warping, it is necessary to equalize the amount of shrinkage on the front and back sides of the raw sheet, and in order to do this, it is necessary to reduce the difference in packing density between the front and back sides of the raw sheet and increase the overall density. is a major point. An object of the present invention is to provide a new method for producing a raw ceramic sheet for firing in order to obtain a high-density sintered sheet with excellent smoothness.

In the present invention, two raw sheets of the same thickness are prepared, and the raw sheet surfaces are brought together face-to-face or in a hair-to-edge relationship and pressed together until the desired thickness is achieved to make one final laminated raw sheet. rear,
The sheet is punched into a desired shape and fired at an optimum firing temperature, resulting in a fired striped sheet with extremely low warpage. In the method of the present invention, first, a predetermined amount of organic components such as a binder, a plasticizer, and a solvent are added to a ceramic material, and the mixture is thoroughly mixed using a known mixing method such as a ball mill or kneader to produce muddy acid having an appropriate viscosity. This mud bran is poured onto a smooth substrate such as an organic film, formed into a sheet with a constant thickness using the doctor blade method, and dried to a thickness of 0.05 mm depending on the application.
A high density green sheet is made with a constant thickness of ~2.0 ribs. The ceramic material packing density of this raw sheet reached 50 to 65% in terms of volume ratio. There is no problem in producing the green sheet using other methods, such as extrusion molding or roll rolling. Next, two of these raw sheets are stacked and pressed together.

(However, the joint surfaces of the raw sheets should be the same as the front or back sides of each raw sheet.) In order to ensure that the leaves and amphipod sheets are well joined, the solvent used to make the mud number on the joint surfaces in advance. Alternatively, the raw sheet may be heated to an extent that does not damage the raw sheet. In this way, two green sheets are laminated to form one green sheet, and then punched into a required shape to form a ceramic green sheet for firing. If the above-mentioned raw sheet is fired at the optimum temperature, an extremely smooth Akatsuki compact sheet can be obtained compared to the Akatsuki compact sheet obtained using a single green sheet made from a sheet forming machine using the conventional method. Ta. The ceramic material used in the method of the present invention is a single powder of alumina (Aso203), magnesia (Mg0), or silica (Si02) or a mixed powder thereof when used as a ceramic substrate; In the case of materials, it is a lead-based piezoelectric material representative of its modified form, P-katana, and in the case of magnetic materials, various ferrite materials, other oxide resistor materials, etc. may be used.

Organic binders include polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, and vinyl chloride.
There are vinyl acetate copolymers, methylcellulose, ethylcellulose, etc., but polyvinyl acetate,
Polyvinyl butyral is preferred. The plasticizer is selected depending on the binder, and for example, phthalate-based, glycol-based, glycerin-based, etc. are used. Both the binder and the plasticizer are used in a range of 1 to 100% from the viewpoint of moldability, processability, and densification of the raw sheet. % is preferred. The solvent varies depending on the ceramic material, but is preferably a single or mixed solvent of water, alcohol, or ketone. The highly smooth and high-density bran aggregate sheet element obtained using the raw ceramic sheet for firing according to the method of the present invention cannot be produced by conventional methods such as cutting and polishing a fired striped body or a single crystal. Compared to elements, there is no processing distortion, so it has excellent electrical and mechanical properties, and it can be supplied at low cost due to reduced processing costs, making it suitable for high-performance electronic components that can be used in a variety of applications depending on the type of ceramic material. Can be applied.

A non-limiting example of the invention is described below. <
Example> 20396 parts of a-A with particle size of about 1 mm, Si022
2. For the ceramic material of 0.22 parts. % by weight of polyvinyl butyral and 1.0% by weight of diptyl phthalate were added, mixed well with methyl alcohol of 4% by weight based on the ceramic material, and further mixed in a ball mill for 24 hours to remove mud. was created.

This mudfish was poured onto a polyester film, and a raw sheet was prepared using the doctor blade method. The thickness of the green sheet at this time was 250 m, and the density was 2.6 mm/ground. Next, this raw sheet was punched into a 2Q mosquito horn shape on each side, and the two raw sheets were pressed together so that the front surface or back surface overlapped, and the method shown in Table 1 was used.

This press-bonded raw sheet for firing was placed in an electric furnace, and after preliminary firing to remove organic components, 160,000, 2
The main firing was performed under the firing conditions of 100 hrs. After firing, the Akatsuki compact sheet was slowly cooled to room temperature and taken out. Although these compacted sheets showed a shrinkage rate of about 15% in the radial direction compared to the raw sheet, they did not exhibit cracks, perforations, or warping and had excellent smoothness. Table 1 shows the pressure bonding method and the density and smoothness of the bran aggregate sheet obtained using the pressure bonding method.

Table 1 As described above, the present invention provides a green sheet from which a composite sheet with excellent smoothness and no warpage can be obtained.

Claims (1)

[Claims] 1. Organic components such as a binder, a plasticizer, and a solvent are added to a ceramic material and kneaded, and the kneaded product is poured onto a smooth base film and spread to a constant thickness using a doctor blade method, and then dried. A raw sheet is produced, then two of these raw sheets are prepared, and the relationship between the front side (the side opposite to the side in contact with the base film) and the front side or the back side (the side in contact with the base film) and the back side of the raw sheet is determined. 1. A method for producing raw ceramic sheets, which comprises stacking them so that the shape of the raw ceramic sheets forms, pressing them together, and simultaneously punching them into a desired shape to form a laminated type. 2. The method for producing a raw ceramic sheet according to claim 1, wherein the raw sheet is heated to an extent that the raw sheet is not damaged during crimping. 3. Claim 1, characterized in that when stacking raw sheets before crimping, the joining surfaces are slightly impregnated with a solvent similar to that contained in the kneaded material, and then crimping is carried out.
A method for producing a raw ceramic sheet as described in .