JPH08333171A - Mold release sheet and sintering of ceramic with the same - Google Patents

Abstract

PURPOSE: To prepare a mold release sheet simple in handling, high in smoothness, using ceramic powder having an arbitrary material quality and an arbitrary particle diameter, high in the content of the ceramic powder and used for sintering ceramics, and further to provide a method for sintering the ceramic with the same. CONSTITUTION: This mold release sheet is produced by adhering ceramic powder to at least one side of a sheet-like article with an adhesive. The method for sintering the ceramic comprises spreading the sheet produced by adhering the ceramic powder to at least one side of the sheet-like article with the adhesive on the lower side of a ceramic molded product to be sintered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release sheet for preventing deformation and welding, which is used for sintering cemented carbide parts such as tungsten carbide and titanium carbide and ceramics such as IC packages and ceramic capacitors. , And a method of sintering ceramics.

[0002]

2. Description of the Related Art When a ceramic or the like is sintered, the dimension of the ceramic compact shrinks as the temperature rises.
If the coefficient of friction between the ceramic compact and the shelf plate or the like on which it is installed is large, the ceramic compact will be distorted or cracked during sintering. Further, depending on the combination of the materials of the ceramic molded body and the shelf board, the ceramic molded body and the shelf board are welded during sintering. In order to prevent these phenomena, ceramic powder is spread between the ceramic molded body and the shelf plate.

[0003]

However, laying the ceramic powder on the shelf plate is not only time-consuming, but also because the smoothness of the surface is not good, the force is concentrated on a part of the ceramic molded body. It was not a fundamental solution because sintering strains would occur.

In order to solve these problems, a release paper has been developed in which ceramic powder is incorporated into paper. The release paper exhibits releasability by burning during sintering and leaving only the ceramic powder. However, due to the limitation of the papermaking method, this release paper is not only able to incorporate high-density and large-diameter ceramic powder, but even small-diameter ceramic powder contains only about 60% by weight. The mold releasability is not fully exerted.

In order to overcome this problem, the present invention uses a ceramic powder having an easy handling, a high smoothness, an arbitrary material and a particle size, and a ceramic powder having a high ceramic powder content. Provided is a release sheet and a ceramics sintering method using the release sheet.

[0006]

The present inventors have found a sheet in which a ceramic powder is adhered to the surface of a sheet-like object using an adhesive.

According to the present invention, not only the particle size and density of the ceramic powder but also ceramics of any material can be used. For example, to adjust the vapor pressure of lead during sintering of PZT, lead oxide powder may be adhered to the sheet-like object, and zirconia, which is difficult to weld for porcelain sintering, may be adhered to the sheet-like object. . From the viewpoint of heat resistance, reactivity, etc., the shape and material of the ceramic molded body and shelf board, such as oxide-based ceramics in the oxidizing atmosphere and carbide-based, boride-based, and nitride-based ceramics in the reducing atmosphere. The most suitable release ceramic powder can be selected.

If the particle size of the ceramic powder is larger than 8 mesh, the unevenness of the contact surface with the ceramic compact becomes rough, and the smoothness of the surface of the ceramic sintered product deteriorates. Also, the particle size of the ceramic powder is 1000
If it is smaller than the mesh, the amount of the ceramic powder that can be bonded is too small, which causes a problem of releasability. Therefore, the particle size of the ceramic powder is from 8 mesh to 100.
0 mesh can be preferably used, but 50 mesh to 240 mesh can be more preferably used.

As the sheet-like object, a substance which does not deform during the temperature rise, for example, a carbon sheet such as an expanded graphite sheet, paper, a sheet-like thermosetting resin or the like can be preferably used. Examples of the expanded graphite sheet used here include those obtained by rapidly heating a sulfuric acid intercalation compound of scaly natural graphite to about 1000 ° C. to expand it about 100 times or more, and then shaping it into a sheet by compression molding. Since the expanded graphite sheet is flexible, the surface smoothness can be further improved by performing roll rolling after bonding the ceramic powder.

Examples of the thermosetting resin include phenol resin, furan resin, epoxy resin and the like, or those obtained by heat-curing these, but the present invention is not limited to these. These resins may be decomposed and carbonized depending on the use temperature, and the present invention includes these use forms as embodiments.

Although it is preferable that the thickness of the sheet-like object is smaller, the ceramic content of the release sheet according to the present invention can be higher than that of the conventional release sheet, so that the weight per unit area becomes heavier and the tensile strength becomes smaller. Constraints occur. Therefore, a sheet-like object having a thickness of 40 μm or less cannot be used practically.

As an adhesive for adhering the sheet-like object and the ceramic powder, an organic adhesive having a low ash content can be preferably used, and an acrylic pressure-sensitive adhesive can be particularly preferably used.

The amount of adhesive is 1 of the particle size of the ceramic powder.
It is preferably used when it is applied to a thickness of / 5 to 4/5. If the amount of the adhesive is less than ⅕ of the particle size of the ceramic powder, the ceramic powder falls off during handling of the release sheet, and the releasability is deteriorated, which is not preferable. Further, if the amount of the adhesive agent is 4/5 or more of the particle diameter of the ceramic powder, it is not preferable because it adheres to the adjacent release sheet during storage of the release sheet.

If the ceramic powder is adhered to one surface of the sheet-like object, the content of the ceramic powder is usually 60-.
Although it is about 90% by weight, if it is insufficient, the content can be increased by adhering to both surfaces. Further, it is also possible to bond different types of ceramic powder to each one surface and individually control the reactivity between the ceramic molded body and the shelf plate and the releasing ceramic powder.

[0015]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited thereto.

Example 1 An acrylic adhesive (55 spray glue manufactured by Sumitomo 3M Co., Ltd.) was coated on one surface of an expanded graphite sheet (PF-20 manufactured by Toyo Tanso Co., Ltd.) having a thickness of 0.2 mm and a density of 1.0 g / cm ^3. ) Was applied at a rate of 1 mg / cm ² , and alumina powder of about 120 mesh (White Alundum WA120 No., Showa Denko KK) was adhered at a rate of 40 mg / cm ² to form a release sheet. The alumina content was about 67%. This release sheet has an average particle size of 2μ
When it was laid under a molded product (diameter 50 × thickness 10 mm) of an equimolar mixture of titanium oxide and barium carbonate of m, and sintered at 1350 ° C., it could be sintered smoothly without cracking or distortion.

Example 2 Vinyl acetate adhesive (Konishi Co., Ltd. woodworking bond) was applied to one side of a copy paper (SS-5 manufactured by Canon Sales Co., Ltd.) having a thickness of 0.1 mm and a density of 0.7 g / cm ^3. 10
30 mg / cm of zirconia powder (about 400 mesh manufactured by Wako Pure Chemical Industries, Ltd.) applied at a rate of mg / cm ^2.
When the release sheet was formed by bonding at a ratio of ² and then drying it, the zirconia content was about 80%. Such a release sheet was formed into a molded product (diameter 50 × thickness 10 × 10) of a mixture of talc having an average particle diameter of 2 μm and silicon oxide (molar ratio 3: 4).
mm) and sintered at 1400 ° C., sintering was possible without cracks or distortion, and welding did not occur.

When each of the ceramic compacts described in Examples 1 and 2 was sintered according to the conventional method, the smoothness of the surface was not good and sintering strain occurred.

[0019]

EFFECTS OF THE INVENTION According to the present invention, it is possible to reduce the furnace filling work before the sintering of the ceramic compact and shorten the time, and to reduce defects such as distortion and cracks during the sintering.

Claims (2)

[Claims] 1. A release sheet in which a ceramic powder is adhered to at least one surface of a sheet-like object using an adhesive. 2. A method of sintering ceramics, comprising laying a sheet having ceramic powder adhered to at least one surface of a sheet-like object with an adhesive on the lower side of a ceramic compact to be sintered.