JPH1179852A - Setter for baking and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a setter for baking free from contamination of foreign matter and provide a method for producing the setter. SOLUTION: This setter for baking has 0.5 mm-5 mm thickness of setter and sintered compact density corresponding to >=95% of theory density and forms independent depressions on the contact face with baked material. The ratio of depressions is within the range of 10-85% and one area of depressions is within the range of 0.07-36 mm and the depth of the depressions is >=0.02 mm and form of depressions is circular form, sector form, cruciate form or the like or a combination of these forms and the material is made of ceramics such as alumina, silica, magnesia, mullite, zirconia, cordierite, silicon nitride or silicon carbide or a composite material consisting essentially of these ceramics. This method for producing the setter comprises subjecting ceramics or the like to press molding by using a mold punch whose surface is processed in uneven shape by machining.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a setter used for firing electronic parts and the like.

[0002]

2. Description of the Related Art Multilayer capacitors, ceramic capacitors including high-voltage capacitors, piezoelectric materials such as piezoelectric ceramics, microwave dielectrics, multilayer LC composite chips, S
High frequency components such as AW filters, semiconductor capacitors, P
Barium titanate (BaTiO ₃ ), lead zirconate titanate (PbZrTiO ₃ ), strontium titanate (SrTiO ₃ ), zinc oxide (ZnO), Oxides such as zirconium oxide (ZrO ₂ ), rare earth oxides, glass materials, and composites thereof are used.

[0003] In general, such electronic parts are prepared by blending these materials, shaping them, and placing them on a firing setter.
By firing at 1400 ° C., a ceramic body is formed, and an element is formed by forming an electrode on this body, and finally a component is obtained by assembling.

In recent years, there has been a demand for miniaturization and weight reduction of AV equipment, OA equipment, home electric appliances, etc., in which capacitors and the like are frequently used, and electronic material parts have been miniaturized. An important problem is contamination of the fired material due to contact with the material, or occurrence of defective products due to adhesion between the fired material and the setter.

[0005] In order to solve such a problem, as a method of making the contact between the fired material and the setter a point contact, a ceramic powder or a sintered body which is less likely to react with the fired material is spread as a powder on the setter and fired. The way to be done. However, in this method, since the ceramic powder adheres to the surface of the fired product, the work of removing the adhered powder occurs, or when the firing temperature is increased, the powders aggregate or adhere to each other. It is difficult to use and needs to be treated as industrial waste.

Further, if the calcined material is small, it takes time and effort to collect the calcined material in the collection operation, and the litter is also collected. Therefore, the removal operation occurs. If the calcined material is large, the calcined material comes into contact with the setter. On the surface, there is a trace of bedding powder,
Problems such as the necessity of finishing such as surface polishing have occurred.

[0007] In addition, ceramics slurry which is difficult to react with the fired material is applied to the surface of the firing setter, or a sprayed material of the same material is coated. However, the aspect of preventing contamination is eliminated. However, there are problems such as high coating cost and foreign matter mixing such as cracking and peeling of the coating layer due to the difference in thermal expansion coefficient between the setter material and the coating layer.

On the other hand, as a method of manufacturing an inexpensive setter in which the contact between the fired material and the setter is point contact, a surface of a molded body is blasted using plastic or glass beads, and a roughened surface is sintered. There is a method to make a setter. However, if a material with a high sintering density and low thermal conductivity is used as the setter material, unevenness in the baked product may occur due to the temperature difference on the setter, and the thickness of the setter must be reduced to prevent this. Must. As the thickness of the setter becomes thinner, the formed body is more likely to be broken during blasting, so that a setter thinner than several mm can hardly be manufactured by this method.

There is also a porous setter, but as the thickness becomes thinner, the strength becomes weaker, and there is a problem that foreign matter is mixed in due to chipping of the setter during handling.

[0010]

As a method of manufacturing a firing setter having a thickness of several mm or less, dry press molding in which powder is molded using a mold, casting molding in which a slurry is poured into a mold, and slurry in a sheet are used. A typical example is a method in which a molded body is manufactured by casting it on a tape and then sintered to form a setter.

However, when a setter surface is formed with an uneven pattern, it is difficult to form the uneven pattern by mechanical working on a mold such as a gypsum mold in casting, and it is difficult to repeatedly form the mold. Type is also a problem. This tends to be more difficult as the size of the depression or protrusion becomes smaller.

Also in tape molding, the more complicated the shape, the more the problem of releasability arises, and if the thickness of the setter is thick, uneven drying and uneven density occur.

In order to solve such a problem, as proposed by the present inventors in Japanese Patent Application No. Hei 8-88477, a resin film or sheet having microspheres adhered to the surface, or depressions or protrusions on the surface. It is inexpensive to use a resin sheet in which the shape of the concavo-convex pattern is formed by machining or the like and press-mold or the like.

However, when the thickness of the resin sheet is reduced, machining or thermal processing becomes difficult, and the size of a single depression after molding becomes smaller and the shape becomes more complicated. The width of the protruding portion becomes narrow, and the sheet is deformed by pressurization during press molding, so that the ridgeline of the molded body becomes unclear or collapsed.

The present invention solves these problems, and since the thickness of the setter is small, heat is easily transmitted to the fired material uniformly, and the fired material is not unevenly burned due to a temperature difference on the setter. Because of its high density, it also has mechanical strength, and an independent depression is formed on the contact surface with the fired material.
Good stability of the fired material on the setter, and the fired material and the setter are close to point contact. Because there is no adhesive, even if used repeatedly,
It is an object of the present invention to provide a setter for firing, in which foreign matter is not mixed and a fired product can be easily collected.

[0016]

According to the present invention, the setter has a thickness in the range of 0.5 mm to 5 mm, has a sintered body density corresponding to 95% or more of the theoretical density, and has a A baking setter characterized in that an independent depression is formed on the contact surface.

Hereinafter, the requirements to be satisfied by the firing setter of the present invention will be described in detail.

(A) Thickness of the setter The thickness of the setter must be in the range of 0.5 mm to 5 mm. The reason is that if the thickness is larger than 5 mm, when a material having a low thermal conductivity is used, there is a possibility that unevenness in the baked product due to a temperature difference on the setter may occur. This is because it is difficult to obtain a molded body having a shape, and it is difficult to form a uniform and clear depressed shape on the surface, and the molded body is easily broken during handling after molding.

(B) Sintered Body Density The sintered body density of the setter is 95% or more, preferably 97% or more of the theoretical density of the material. The reason is that if the density of the sintered body is less than 95%, the mechanical strength is inferior, so that chipping may occur at the time of handling, and the chipping may be mixed in when collecting the fired material. Also, even during firing, the setter may be warped and cannot be reused.

(C) Depressed Size Even if the depressed shapes of the same size are formed, there are some which are in point contact and others are not, depending on the area in which the fired material comes into contact with the setter. one area of collapse is, preferably in the range of 0.07mm ² ~36mm ^2, more preferably, it may be in the range of 0.2mm ² ~16mm ^2. In particular, from the viewpoint of the stability of the fired product on the setter, it is preferable to select one in which one area of the depression is smaller than 1/2 of the installation area of the fired product.

If the area of one of the depressions is smaller than 0.07 mm ² , the surface is not inferior to a flat surface but close to surface contact. Therefore, as the firing temperature increases, the fired material and the setter may adhere. Also, when one area of the depression is larger than 1/2 of the installation area of the fired material on the setter or larger than 36 mm ^2, if the fired material is small, it enters into the depression and is close to surface contact. Therefore, as the firing temperature increases, the fired material and the setter may adhere to each other, or the fired material may be deformed by being tilted and fired, or the fired material may have a trace of the setter. Must be finished by surface polishing or the like.

(D) Depression rate of the surface The depression rate of the depression formed on the setter surface with respect to the setter surface area is preferably in the range of 10 to 85%, more preferably in the range of 20 to 75%. Good to be. If it is less than 10%, the surface is not inferior to a flat surface, and as the firing temperature increases, the fired product and the setter may be bonded. On the other hand, if it is larger than 85%, the width of the protruding portion connected in a ridge line around the depressed portion becomes thin, and the uneven pattern becomes unclear, so that it becomes difficult to process.

(E) Shape of the Depression The shape of the independent depression is not particularly limited, but is easily processed, such as a circle, a semicircle, an ellipse, a fan, a slot, a star, a cross, and a polygon. Or a shape obtained by rounding the corners of these shapes or a combination of these shapes is preferable. In the case of a polygon, the number of corners is not limited, but the number is preferably 10 or less, more preferably 3 to 6 in terms of ease of machining.

(F) Depth of Depression The depth of the depression is 0.0
It is sufficient if it is 2 mm or more, and more preferably, 0.02 to
The thickness is preferably within a range of 0.4 mm, but is preferably 1/4 or less of the thickness of the setter from the viewpoint of strength at the time of molding.
If the thickness is less than 0.02 mm, the surface has a smoothness comparable to that of a flat surface. Therefore, as the firing temperature increases, the fired product and the setter may be bonded. If it is deeper than 0.4 mm, the releasability of the molded body from the mold may be deteriorated.

(G) Setter Material Materials for the setter include ceramics such as alumina, silica, mullite, magnesia, zirconia, cordierite, silicon nitride and silicon carbide, and composite materials containing these as main components. The material for forming an independent depression on the surface is not particularly limited.

For example, in the case of zirconia, since the bulk density is higher and the thermal conductivity is lower than other materials, a temperature difference occurs on the setter depending on the sintering conditions, and the sintering may cause unevenness in the sinter. It had occurred. For this reason, measures to reduce productivity, such as slowing down the heating rate, were needed.However, this phenomenon was considerably mitigated by reducing the thickness of the setter and forming an independent depression on the surface. You.

(H) Method of forming depressions As a method of continuously and inexpensively obtaining a molded body having independent depressions formed on the surface, dry press molding using a mold is preferable.

On the upper punch or lower punch surface of the mold,
The shape opposite to the shape desired to be formed on the molded body is formed by mechanical processing or the like in consideration of the shrinkage rate during firing so that the size and depth of the depression after firing are within the range. Dry press molding is performed using this mold, but as the molding pressure increases or the depth of the depression increases, the releasability of the molded body from the mold deteriorates. To improve
It is preferable to apply a release agent to the molding surface or to taper the processing surface of the die punch.

On the other hand, there is a method in which a resin sheet made of polycarbonate or the like is formed into a similar shape by machining or the like without being processed into a mold punch. There is no problem when the surface depression rate is low, but as the depression rate on the molded body surface increases, the width of the projections connected in a ridge line around the depression becomes narrower, so the molding pressure increases. If the depth of the depression becomes large, the sheet may be deformed by pressure during molding, and the ridgeline of the molded product may become unclear or collapse, and a setter in which an independent depression is formed cannot be obtained.

(I) Powder properties When a compact having independent depressions is obtained by dry press molding, the powder is preferably in a form having a good filling property in a mold, and is dried using a spray drier. Granular materials having good fluidity are preferred. In order to obtain a setter having a sintered body density equivalent to 95% or more of the theoretical density, a powder having good sinterability must be used. It is preferable to use a powder of
The following is good.

The thinner the setter is, the more easily it breaks during handling. Therefore, the appropriate amount of addition differs depending on the type and particle size of the raw material or the production method.
It is preferable to use granules to which several percent of a synthetic water-soluble polymer such as VA or PEO is added. In particular, it is preferable to add a binder containing an acrylic resin as a main component because of its excellent thermal decomposability.

Hereinafter, a method for producing a zirconia setter which is an example of the firing setter of the present invention will be described.

The zirconia powder used for the zirconia setter is produced by electrofusion, hydrolysis, neutralization coprecipitation,
There are hydrolysis-neutralization method, hydrothermal oxidation method, thermal decomposition method, alkoxide method, etc., but there is no particular limitation, but the strength of the molded body during handling and the sharpness of the shape of the concavo-convex pattern of the molded body, From sinterability, the average particle size is 2
It is preferable to use a powder of μm or less.

Further, MgO, CaO,
Rare earth oxides such as Y ₂ O ₃ and CeO ₂ are often used. However, when used as a setter, they need only be thermally and mechanically stable, and there is no particular need to limit the stabilizer. For example, in the case of Y ₂ O ₃ , the molar ratio of Y ₂ O ₃ / ZrO ₂ is preferably 1.5 / 98.5 to 6.0 / 94.0. If the ratio is less than 1.5 / 98.5, the amount of monoclinic zirconia increases, and the setter becomes weaker in thermal shock resistance due to transition. If the ratio exceeds 6.0 / 94.0, the mechanical strength increases as the setter thickness decreases. Are weak and cannot be reused.

In addition to the stabilizer and the unavoidable components,
To improve heat resistance and mechanical strength, Al ₂ O ₃ , Ti
Oxides such as O ₂ and SiO ₂ or their compounds may coexist. The content does not need to be limited as long as it does not react with or adhere to the fired product at the time of firing. If the content is more than 30% by mass, the original properties of zirconia such as toughness will be reduced.

For example, an average particle size of 1 μm containing no stabilizer
m or less, 3 mol% of the yttria powder as a stabilizer is added to the zirconia powder, and the mixture is pulverized and mixed by a wet method to obtain a zirconia slurry having a slurry concentration of 50%. Furthermore, after adding the solid content concentration to 5% with respect to the solid content of the slurry from which the binder containing the acrylic resin as the main component was obtained, 100% was added with a thickener.
The viscosity is adjusted to 0 cP and dried and granulated in the air using a rotary disk type spray dryer to obtain zirconia granules having an average granule diameter of 50 μm. After firing, setter thickness is 1m
m, put the obtained granules in a mold so that the size becomes 100 mm x 100 mm, and then, after firing, the shape of the depression is square, the rate of depression of the surface is 59.2%, and the maximum area of one depression Is punched into a mold that has been machined so that the pitch between the depressions is 1 mm ² , the pitch between the depressions is 1.3 mm, and the depth of the depressions is 0.1 mm.
^By press-molding at a molding pressure of ² , a molded body having an independent depression formed on the surface is obtained. A warp prevention setter is placed on the obtained molded body, and the baking furnace is used in the air for 150 minutes.
By baking at 0 ° C., a baking setter having a sintered body density corresponding to 95% or more of the theoretical density and having an independent depression formed on the surface is obtained.

[0037]

As described above, in the firing setter of the present invention, since the thickness of the setter is thin, heat is easily transmitted to the fired product uniformly, and there is no uneven firing of the fired material due to a temperature difference on the setter. Because of the high unity density, there is also mechanical strength,
An independent depressed shape is formed on the contact surface with the fired material, so the stability of the fired material on the setter is good, and the fired material and the setter are close to point contact, so even if the firing temperature increases, firing Since the material and the setter are not easily adhered to each other and there is no adhesive such as a litter or a sintered body on the surface of the setter, even if used repeatedly, there is no foreign matter mixed in and the fired material can be easily collected.

When this setter is used, even if a fired material having a large glass component is fired at a temperature close to the melting temperature of the glass, the fired material and the setter are hardly adhered to each other, and the fired material can be easily collected. In addition, since no litter is used, there is no problem of industrial waste.

By using the firing setter, it is possible to meet strict requirements regarding manufacturing conditions, such as prevention of adhesion with the setter due to downsizing of the fired product or prevention of adhesion as the firing temperature is increased.

[0040]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 Commercially available zirconia powder (TZ-3YSB) manufactured by Tosoh Corporation
-C: granules, binder addition amount 5%) 60 g is put into a molding die having a size of 130 mm x 130 mm, and after firing, the shape of the depression is a circle having a diameter of 0.5 mm, and the rate of depression of the surface is 2
2.7%, the area of one depression is 0.2 mm ² , the pitch between depressions is 1 mm (60 ° staggered), and the depth of depression is 0.07
mm on the die that has been machined to
A release agent was applied to the molding surface and press-molded at a molding pressure of 400 kg / cm ² . The obtained compact was set on an alumina setter for firing, and a warp prevention setter was placed on the upper surface thereof.
Baking under the condition of time, sintered body density 6.01 g / cm
³ was obtained in the calcined product with circular depression is formed in the zirconia setter separate the contact surface (theoretical density 98.5% equivalent) (100 mm × 100 mm × thickness 1 mm). The tip of the processing surface of the upper punch was tapered.

On the zirconia-based setter, 10 compacts each made of barium titanate and having a width of 3 mm, a length of 5 mm, and a thickness of 2 mm (installation area: 15 mm ² ) were placed. After firing for 2 hours, there was no reaction or adhesion between the setter and the fired product.

Example 2 120 g of the same zirconia granules as in Example 1 were placed in a molding die of the same size as in Example 1, and the shape of the depression after firing was 1
1 mm square, 59.2% surface depression rate, 1 depression
An upper punch is machined so that the area of each piece is 1 mm ² , the pitch between the depressions is 1.3 mm (parallel type), and the depth of the depressions is 0.1 mm, and the release agent is applied to the molding surface. Apply,
Press molding was performed at a molding pressure of 600 kg / cm ² . The obtained molded body was set on an alumina setter for firing, a warp prevention setter was placed on the upper surface thereof, and fired in an electric furnace at 1450 ° C. for 2 hours under an air atmosphere, and the sintered body density was 6.03 g. / Cm ³ (corresponding to 98.8% of theoretical density) with a zirconia setter (100 mm × 100 mm) having an independent square depression formed on the contact surface with the fired material.
× thickness 2 mm). The tip of the processing surface of the upper punch was tapered.

On the zirconia-based setter, 10 compacts each made of barium titanate and having a width of 3 mm, a length of 5 mm, and a thickness of 2 mm (installation area: 15 mm ² ) were placed, and at 1330 ° C. in an air atmosphere in an electric furnace. After firing for 2 hours, there was no reaction or adhesion between the setter and the fired product.

Example 3 A commercially available zirconia powder manufactured by Tosoh Corporation (TZ-3YB:
Granules, binder addition 3%) 60 g in size 130
After being put into a molding die having a size of 130 mm × 130 mm, the shape of the depression after firing is a long hole having a width of 1 mm × length of 3 mm, the surface depression rate is 34.8%, the area of one depression is about 3 mm ² , The upper punch of the machined die was machined so that the horizontal pitch was 4 mm, the vertical pitch was 2 mm (parallel type), and the depth of the depression was 0.2 mm, the release agent was applied to the molding surface, and 500 kg / c
Press molding was performed at a molding pressure of m ² . The obtained molded body was set on an alumina setter for firing, and a warp prevention setter was placed on the upper surface thereof.
It is fired under the conditions of 0 ° C. and holding for 2 hours, and the sintered body density is 5.96.
A zirconia-based setter (100 mm × 100 mm × 1 mm thick) was obtained in which an independent slot-shaped depression was formed on the contact surface with the fired product of g / cm ³ (equivalent to 97.7% of the theoretical density). The tip of the processing surface of the upper punch was tapered.

On the zirconia-based setter, 10 compacts each made of barium titanate and having a width of 3 mm, a length of 5 mm, and a thickness of 2 mm (installation area: 15 mm ² ) were placed, and at 1330 ° C. in an electric furnace under an air atmosphere. After firing for 2 hours, there was no reaction or adhesion between the setter and the fired product.

Comparative Example 1 60 g of the same zirconia granules as in Example 1 were placed in the same molding die as in Example 1, and were preformed with an unmachined upper punch at a molding pressure of 30 kg / cm ² . . Next, only the upper punch of the mold was pulled out, and after firing the surface of a polycarbonate sheet (PC sheet) having the same surface area as the upper punch surface and a thickness of 1 mm, the shape of the depression was a circle having a diameter of 2 mm, and the depression rate of the surface was 7. 5%, one sinking area is 3.1
4mm ² , pitch between depressions 7mm (60 ° staggered),
Machined so that the depth of the depression is 0.07 mm, P
Set the machined surface of the C sheet toward the molded body,
After inserting the upper punch again, press molding was performed at a molding pressure of 400 kg / cm ² . The PC sheet of the obtained molded body was peeled off, the molded body was set on an alumina setter for firing, a warp prevention setter was placed on the upper surface thereof, and fired under the same conditions as in Example 1, and the sintered body density was 6.01 g / cm. ³ (9 of theoretical density
8.5% zirconia setter (100 mm x 1) with an independent circular depression formed on the contact surface with the fired material
00 mm x thickness 1 mm). Also, the releasability of the molded article and the mold was good.

On the zirconia-based setter, 10 compacts each made of barium titanate and having a width of 3 mm, a length of 5 mm, and a thickness of 2 mm were placed, and were placed in an air furnace in an air atmosphere.
Although firing was performed at 30 ° C. for 2 hours, the contact between the setter and the fired product was close to surface contact, and a part of the fired product adhered.

Comparative Example 2 60 g of the same zirconia granules as in Example 1 were placed in a molding die of the same size as in Example 1, and after firing, the shape of the depression was a square having a side of 2 mm and the rate of depression of the surface was 90.7. %, The area of one depression is 4 mm ² , the pitch between depressions is 2.1 mm (parallel type), and the upper punch of a machined die is placed so that the depth of depression is 0.1 mm. Apply release agent, 6
Press molding was performed at a molding pressure of 00 kg / cm ² , but the projections connected in a ridge line around the depressions at the time of mold release collapsed, and the independent depressions became unclear.

[Brief description of the drawings]

FIG. 1 is a top view of a circular parallel type depressed setter and an equation for calculating the depressed rate.

FIG. 2 is a top view of a circular 60 ° staggered depression setter and a formula for calculating the depression ratio.

FIG. 3 is a top view of a square staggered depression setter and a formula for calculating the depression rate.

FIG. 4 is a top view of a long hole parallel type depressed setter and a formula for calculating the depressed rate.

[Explanation of symbols]

 D: Depressed hole diameter (mm). P: pitch between depressions (mm). W: Width of depression (mm). L: Depression length (mm). EC: lateral pitch (mm) between depressions. SC: vertical pitch (mm) between depressions.

FIG. 5 is an example of a top view of another depressed setter shape.

FIG. 6 is a top view example of another depressed setter shape.

FIG. 7 is a top view example of another depressed setter shape.

FIG. 8 is an example of a top view of another depressed setter shape.

FIG. 9 is a top view example of another depressed setter shape.

FIG. 10 is a top view example of another depressed setter shape.

FIG. 11 is a top view example of another depressed setter shape.

FIG. 12 is an example of a top view of another depressed setter shape.

Claims (7)

[Claims] The thickness of the setter is from 0.5 mm to 5 mm.
Characterized by having a sintered body density of 95% or more of the theoretical density, and having an independent depression formed on a contact surface with the fired material. 2. The area of one depression according to claim 1 is 0.
A firing setter characterized by being in the range of from 07 mm ² to 36 mm ² . 3. The firing setter according to claim 1, wherein the surface depression rate of the depression is in the range of 10% to 85%. 4. A firing setter according to claim 1, wherein the depth of the depression is 0.02 mm or more. 5. The depression according to any one of claims 1 to 4, wherein the shape of the depression is a circle, a semicircle, an ellipse, a sector, a slot,
A firing setter having a shape such as a star, a cross, a polygon, or the like, or a shape obtained by rounding the corners, or a combination of these shapes. 6. The setter according to any one of claims 1 to 5, wherein the material of the setter is ceramics such as alumina, silica, magnesia, mullite, zirconia, cordierite, silicon nitride, silicon carbide or the like. A firing setter characterized by comprising a composite material as a component. 7. The setter according to any one of claims 1 to 6, wherein the setter is press-formed using a mold punch whose surface has been processed into an uneven shape by machining or the like, and then fired. To produce a firing setter.