JPS6338637B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an adhesive sheet for firing ceramics, which is used when stacking and firing a plurality of thin ceramic sheets, and in particular, it can be used to mass-produce smooth, high-density thin ceramic sheets with little warpage. The purpose of the present invention is to provide an adhesive sheet for firing ceramics. Recently, application products using thin ceramic sheets have been actively developed in the field of electronic components. There is a high demand for the precision of ceramic sheets, and at the same time, there are also high expectations for lower prices.

[Conventional technology]

Conventionally, ceramic elements have been supplied by cutting and polishing a sintered body or single crystal ingot into a predetermined shape, but this method suffers from deterioration of electrical characteristics due to processing distortion and is also expensive. There was a problem. Therefore, for the purpose of simplifying the process and improving mass productivity, there is a need for a method of obtaining elements of a predetermined shape at low cost at the same time as firing. The general method for manufacturing thin plate-shaped sintered bodies is to knead and mold ceramic materials with a binding substance, create a green sheet of a certain thickness, punch it into a predetermined shape depending on the application, and then fire it. In order to improve mass production, the punched raw sheets are made by attaching fine powder of other inorganic materials (hereinafter referred to as inorganic fine powder) to the surface of the ceramic material, which does not easily react with the ceramic material during high-temperature firing, and then stacking multiple sheets and firing them. A method is used. The methods for attaching this inorganic fine powder include: A method in which punched raw sheets are lined up and a sieve is used to uniformly adhere the inorganic fine powder onto the raw sheet A method in which the raw sheet is charged with electricity and the inorganic fine powder is attached to the surface of the raw sheet Inorganic There is a method in which a suspension of fine powder in a solvent is applied onto a ceramic sheet and then dried.

[Problems to be solved by the invention]

, For the method of handling the powder,
Uneven adhesion was likely to occur, and warping and denting of the sintered body were unavoidable. Although method (2) enables more uniform adhesion than method (2) above, it requires a process and drying equipment for applying and drying the solvent suspension onto the ceramic sheet, resulting in low production efficiency.

[Means to solve the problem]

The present invention has been made to solve these problems, and includes uniformly containing or at least a fine inorganic material powder with an average particle size of 5 to 150 μm that does not react with the raw ceramic sheet during high-temperature firing. An adhesive sheet for firing ceramics having a thickness within a predetermined range, the surface layer of which is uniformly formed on one surface, and whose surface layer on at least one side is made of an adhesion promoter is placed between a plurality of raw ceramic sheets. By adhering them with an adhesion agent, interposing them, laminating them, and then sintering them, it is possible to mass-produce smooth, high-density thin ceramics with little warpage. The sheet of the present invention is made of a base material made of paper or plastic containing no inorganic filler, which uniformly contains fine inorganic material powder with an average particle size of 5 to 150 μm, or has it uniformly on at least one surface. An adhesive sheet for ceramic firing, characterized in that the surface layer on at least one side is composed of an adhesion promoter, and has a total thickness of 0.02 to 1.5 mm, and further has an average particle size of 5 to 150 μm. The total thickness obtained by coating and drying a pressure-sensitive adhesive on the surface of inorganic fine powder compounded paper or compounded film, in which inorganic fine powder is pre-blended by a method such as mixing or blending into paper or plastic film, is 0.02.
It is also possible to use a sheet with a thickness of 1.5 mm to 1.5 mm, with release paper laminated on one or both sides to prevent the pressure-sensitive adhesive from adhering. Further, as the adhesion imparting agent, a rewetting type adhesive can be used instead of the pressure-sensitive adhesive. In this case, there is an advantage that it is not necessary to use a release paper to prevent adhesive adhesion, and that the raw sheets can be easily moved after being laminated. The structure of the above-mentioned sheet of the present invention is explained using enlarged sectional views. Figure 1 shows a case where a rewetting type adhesive is used as the adhesion imparting agent, and Figure 2 shows a pressure-sensitive adhesive blended with fine inorganic material powder. Figure 3 shows a case where a pressure-sensitive adhesive is applied to both sides of a base material containing fine inorganic powder inside, and in the drawing, 1 is the base material and 2 is the base material. Inorganic material fine powder, 3
4 indicates an adhesion-imparting agent, and 4 indicates a release paper. Japanese Patent Publication No. 60-8991 discloses the use of paper or plastic sheets containing bedding powder, but
Since the base paper or sheet does not have a method of imparting adhesive properties, the base paper or plastic is carbonized and burned during the initial stage of high-temperature firing of the raw ceramic sheet. When shrinkage occurs, the raw ceramic sheet and the base material slip easily, the dimensions of the base material become smaller than the raw ceramic sheet, and heat fusion and warping occur due to partial contact between the stacked raw ceramic sheets. becomes a problem. The present invention uses paper, plastic film, and foamed plastic sheets whose surfaces are coated with an adhesion agent, thereby achieving dimensional fluctuations between the raw ceramic sheet and the paper or plastic due to thermal shrinkage of the paper or plastic during the initial stage of high-temperature firing. It has been discovered that since direct contact between stacked raw ceramic sheets does not occur, a smooth high-density thin ceramic sintered body without warpage can be obtained. As an inorganic fine powder, the average particle size is 5 to 150μ.
At least one oxide selected from B, Mg, Al, Si, Ti, Zr having m or B, Si,
At least one carbide selected from Ti, Ta, and W can be used. In addition, if the average particle size of the inorganic fine powder is less than 5 μm, the surface area of the fine powder becomes large, which may cause a reaction with the raw ceramic sheet during sintering.
If the diameter exceeds 150 μm, it is difficult to make the inorganic fine powder exist uniformly on the surface or inside the base material, and thin ceramic sheets fired using sheets containing such large powders may have warpage or surface roughness. oxidation is likely to occur. In order to obtain a smooth thin plate-like ceramic without warping, the average particle size of the inorganic fine powder is suitably 5 to 150 μm. The total thickness including the base material is preferably 0.02 to 1.50 mm; if the total thickness exceeds 1.50 mm, it is difficult to suppress dimensional fluctuations due to thermal shrinkage of paper/plastic in the initial stage of high-temperature firing, and the base material Internal slippage is also likely to occur, resulting in the problem that stacked raw sheets may become misaligned. The adhesive properties of the present invention include resins such as polyacrylic acid alkyl ester, polymethacrylic acid alkyl ester, ethylene vinyl acetate copolymer, polyvinyl acetate styrene butadiene rubber, isoprene rubber, etc., and tackifiers, etc. Pressure-sensitive adhesives containing adjuvants such as auxiliary agents, or rewetting adhesives containing starch, dextrin, carboxymethyl cellulose, polyvinyl alcohol, and polyvinyl acetate singly or in combination are used. As the base material, paper containing no inorganic filler such as calcium carbonate, clay, or kaolin, or a plastic film such as polyethylene, polypropylene, polyethylene terephthalate, or ethylene vinyl acetate copolymer, or a foamed plastic sheet such as polystyrene or polyurethane is used. . When paper containing inorganic fillers such as calcium carbonate, clay, and kaolin is used, inorganic materials other than the carbides and oxides selected as the above-mentioned inorganic material fine powder are blended, and fine ceramics such as those of the present invention are mixed. The adhesive sheet for ceramic firing, which is the raw material, not only requires extremely high purity, but also has the risk of causing a reaction during firing, so paper that does not contain inorganic fillers should be used. According to the present invention, it is possible to obtain smooth, high-density, thin plate-shaped ceramic without warping with good mass productivity without causing partial contact between a plurality of stacked raw ceramic sheets.

[Examples and effects of the invention]

Examples of the present invention will be described below. Example 1 10% by weight of alumina (Al ₂ O ₃ ) adjusted to a particle size of 20 μm was added to an emulsion-based pressure-sensitive adhesive mainly composed of ethyl acrylate, and stirred thoroughly to create a suspension. It was applied to both sides of filler-free high-quality paper (100 g/m ² ) to a coating thickness of 50 μm and dried to produce an adhesive sheet containing fine alumina powder. Next, the adhesive sheet was laminated between two raw ceramic sheets with a thickness of 0.7 mm made of alumina adjusted to 0.4 μm and an organic binder, and heated at a temperature of 1700°C for 2 hours in an oxidizing atmosphere. Fired. The obtained sintered body was a highly smooth ceramic sheet with no fusion between the ceramic sheets and no warpage or cracks. Example 2 Magnesia (MgO) adjusted to a particle size of about 25 μm was mixed with starch/polyvinyl alcohol.
Add 35% by weight to 40/60 parts rewetting adhesive,
A suspension was prepared by stirring well, and applied to both sides of filler-free high-quality paper (100 g/m ² ) to a coating thickness of 70 μm, and dried to prepare an adhesive sheet containing fine magnesia powder. The obtained sheet was placed on a raw ceramic sheet made of magnesia (MgO) whose particle size was adjusted to 0.6 μm and an organic binder, and minute water droplets were sprayed onto the sheet using a mist sprayer. Furthermore, one more raw magnesia ceramic sheet was placed on top of the adhesive sheet and fired at a temperature of 2000° C. for 2 hours in an oxidizing atmosphere. The obtained sintered body was a highly smooth ceramic sheet with no fusion between the ceramic sheets and no warpage or cracks. Comparative Example 1 10% by weight of alumina (Al ₂ O ₃ ) adjusted to a particle size of 1 μm was added to an acrylic acid ethyl ester pressure-sensitive adhesive, stirred well to create a suspension, and then mixed with filler-free high-quality paper. (100 g/m ² ) was coated on both sides at a coating thickness of 40 μm and dried to obtain an adhesive sheet containing fine alumina powder. Firing was carried out in the same manner as in Example 1, and the obtained sintered body was a ceramic sheet with impaired surface smoothness due to fusion of the alumina fine powder and the alumina sheet. Comparative Example 2 10% by weight of alumina fine powder adjusted to a particle size of 25 μm was added to acrylic acid ethyl ester latex, stirred well to create a suspension, and a suspension was prepared using filler-free high-quality paper (100 g/m ² ). Coating thickness on both sides
It was coated with a thickness of 50 μm and dried to produce alumina surface coated paper. The coated paper has no adhesive properties with the raw alumina sheet. Thereafter, firing was carried out in the same manner as in Example 1, and in the obtained sintered body, the paper coated with alumina fine powder shrank and the alumina fine powder was locally present, causing the sintered bodies to bond with each other. Partial fusion was observed. Example 3 15% by weight of magnesia (MgO) powder adjusted to a particle size of 50 μm was added to a rewetting adhesive containing 40/60 parts of starch/polyvinyl alcohol.
A suspension was created by stirring well. This suspension was applied to a foamed polystyrene sheet (expansion ratio 10 times, thickness
600 μm) to a coating thickness of 90 μm, and dried to create a rewetting adhesive foam sheet containing fine magnesia powder. Thereafter, the ceramic sheet was fired in the same manner as in Example 2, and a highly smooth ceramic sheet without warping was obtained. Example 4 Silicon carbide (SiC) adjusted to a particle size of 15 μm
was added in an amount of 12% by weight to an emulsion-based pressure-sensitive adhesive containing acrylic acid ethyl ester as the main component, stirred well to create a suspension, and an adhesive sheet containing silicon carbide fine powder was prepared in the same manner as in Example 1. Created. Next, 0.6 mm thick 2.
The adhesive sheet was interposed and laminated between two raw ceramic sheets and fired at a temperature of 2200° C. for 2 hours in a reducing atmosphere. The obtained sintered body was a highly smooth ceramic sheet with no fusion between the ceramic sheets and no warpage or cracks. From the above results, it is clear that by firing a raw ceramic sheet using the adhesive sheet containing inorganic fine powder of the present invention, a highly smooth ceramic sintered body without warping can be easily obtained.

[Brief explanation of the drawing]

The drawings are enlarged cross-sectional views of the structure of the sheet of the present invention. Figure 1 shows the case where a rewetting type adhesive is used as the adhesion imparting agent, and Figure 2 shows the case where a pressure-sensitive adhesive containing fine inorganic material powder is used. In the case where the pressure sensitive adhesive is applied to one side of the material, FIG. 3 shows the case where the pressure sensitive adhesive is applied to both sides of the base material containing the inorganic material fine powder inside. 1... Base material, 2... Inorganic material fine powder, 3... Adhesive agent, 4... Release paper.

Claims (1)

[Claims] 1 One or more carbides selected from B, Si, Ti, Ta, and W or one or more oxides selected from B, Mg, Al, Si, Ti, and Zr. , the surface layer on at least one side of a base material made of paper or plastic without an inorganic filler that uniformly contains fine inorganic material powder with an average particle size of 5 to 150 μm is made of an adhesion promoter, and 0.02 An adhesive sheet for ceramic firing, characterized by having a total thickness of ~1.5 mm. 2. The adhesive sheet for firing ceramics according to claim 1, wherein the base material is a plastic film. 3. The adhesive sheet for firing ceramics according to claim 1, wherein the base material is a foamed plastic sheet. 4. The adhesive sheet for firing ceramics according to any one of claims 1 to 3, wherein the adhesion imparting agent is a pressure-sensitive adhesive. 5. The adhesive sheet for firing ceramics according to any one of claims 1 to 3, wherein the adhesion imparting agent is a rewetting type adhesive. 6 One or more carbides selected from B, Si, Ti, Ta, and W or one or more oxides selected from B, Mg, Al, Si, Ti, and Zr, with an average particle size of 5 The surface layer on at least one side of a base material made of paper or plastic without inorganic filler and having inorganic material fine powder of ~150 μm uniformly on at least one surface is composed of an adhesion imparting agent, and
An adhesive sheet for ceramic firing, characterized by having a total thickness of 0.02 to 1.5 mm. 7. The adhesive sheet for firing ceramics according to claim 6, wherein the base material is a plastic film. 8. The adhesive sheet for firing ceramics according to claim 6, wherein the base plastic is a foamed plastic sheet. 9. The adhesive sheet for firing ceramics according to any one of claims 6 to 8, wherein the adhesive agent is a pressure-sensitive adhesive. 10. The adhesive sheet for firing ceramics according to any one of claims 6 to 8, wherein the adhesion imparting agent is a rewetting type adhesive.