JPH0532350B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention provides a novel aluminum nitride composition that can be used as a raw material for aluminum nitride green sheets and aluminum nitride sintered sheets that are sintered bodies thereof. [Prior art and problems to be solved by the invention] Conventionally, in various industrial and consumer electronic devices, ceramic substrates have been used for mounting electronic devices such as transistors, ICs, and LSIs, forming circuits, and insulating them. is used. For example, an alumina substrate is a typical example. However, in recent years, the heat conductivity of alumina substrates is insufficient in fields that require particularly high thermal conductivity, such as power transistors and high-power hybrid ICs, and there has been a demand for the development of high thermal conductivity ceramic substrates as an alternative. For this purpose, attempts have been made to develop highly thermally conductive ceramic substrates using various ceramics. however,
At present, a highly thermally conductive ceramic substrate that is industrially satisfactory has not yet been developed. Based on the above background, the inventors of the present invention have earnestly attempted to develop a highly thermally conductive ceramic substrate. If only the performance of high thermal conductivity is compared, for example, an aluminum nitride sintered body has a high thermal conductivity several times that of an alumina sintered body. Therefore, with the aim of obtaining a highly thermally conductive aluminum nitride sintered sheet, the present inventors have conducted repeated research on an aluminum nitride composition that can be suitably used as a raw material for the aluminum nitride sintered sheet. As a result, we discovered an aluminum nitride green sheet that can be suitably used in the production of sintered aluminum nitride sheets, and an aluminum nitride composition that is a raw material for the aluminum nitride green sheet, which we have already proposed (Japanese Patent Application No. 59-22982). ). As a result of further research on the above-mentioned aluminum nitride composition, the present inventors found that when aluminates were used as a sintering aid, which is a component in the aluminum nitride composition, these aluminates were oxidized. Despite the fact that the resulting aluminum nitride sintered sheet has a lower oxygen content than the aluminum nitride powder used as a raw material, it has high purity and high thermal conductivity with low oxygen content. It has been found that a transparent aluminum nitride sintered sheet, in some cases a translucent aluminum nitride sintered sheet, can be obtained. The oxygen contained in the aluminum nitride sintered sheet is thought to exist as aluminum oxide, and if an aluminate containing aluminum oxide as a component is added, the oxygen content in the aluminum nitride sintered sheet can be further increased. It is expected that this will happen. However, as mentioned above, the unexpected finding was that by using aluminate as a sintering aid, the oxygen content in the resulting aluminum nitride sintered sheet was lower than that of the raw material aluminum nitride powder. The inventors obtained the following. The present invention was completed based on such knowledge. [Means for Solving the Problems] That is, the present invention provides (i) aluminum nitride powder; (ii)
A binder made of an organic polymer compound that decomposes at a temperature of 1400°C or lower, and (iii) a general formula _n MO・Al ₂ O ₃・_o H ₂ O [where M is an alkaline earth metal and m is 1
or more, and n is a number of 0 or more. ] The binder consists mainly of a sintering aid consisting of an aluminate salt shown in
0.1 to 30 parts by weight per 100 parts by weight, and the sintering aid is 0.01 parts by weight per 100 parts by weight of aluminum nitride powder.
This is an aluminum nitride composition containing ~5 parts by weight. Note that aluminum nitride in the present invention is a 1:1 compound of aluminum and nitrogen, and anything other than this is treated as an impurity in principle.
However, on the surface of aluminum nitride powder, Al-N bonds that are inevitably oxidized in the air replace Al-O bonds, so aluminum with Al-O bonds is not considered a cationic impurity. .
Also, components that serve as sintering aids are not considered cationic impurities. Furthermore, the average particle diameter in the present invention refers to the volume-based median particle diameter measured by a light transmission type particle size distribution analyzer. As the aluminum nitride powder used in the present invention, any known aluminum nitride powder can be used without any restriction. There is a tendency that the lower the oxygen content in the aluminum nitride powder, the greater the effect of reducing the oxygen content in the aluminum oxide sintered sheet by adding the sintering aid. Therefore, the aluminum nitride powder used in the present invention preferably has an oxygen content of 3.0% by weight or less. Further, it is preferable that the particles of aluminum nitride powder used in the present invention have small particle diameters. For example, the average particle size (meaning the average particle size of aggregated particles measured with a centrifugal particle size distribution analyzer, such as CAPA500 manufactured by Horiba, Ltd.) is preferably 5 μm or less. Powders with a diameter of 3 μm or less, most preferably 2 μm or less are used. Especially 3μm
Powders containing 70% by volume or more of the following particles are suitable. In addition, in order to obtain a highly thermally conductive aluminum nitride sintered sheet, aluminum nitride powder with an AlN content (calculated from the nitrogen content of the AlN powder) of 90% by weight or more is preferably used;
It is preferable to use a powder of 97% by weight or more in order to obtain a sintered body having high translucency. The aluminum nitride powder preferably used in the present invention is a powder with an average particle size of 3 μm or less, an oxygen content of 3.0% by weight or less, and a cationic impurity contained when the aluminum nitride composition is AlN. Aluminum nitride powder containing 0.5% by weight or less. When such aluminum nitride powder is used, the thermal conductivity of the obtained sintered aluminum nitride sheet is greatly improved, and therefore it is preferably used in the present invention. Especially, the average particle size is
Powder of 2μm or less, 70% by volume of particles of 3μm or less
When using aluminum nitride powder containing the above, the oxygen content is 1.5% by weight or less, and the cation impurity contained is 0.3% by weight or less when the aluminum nitride composition is AlN, the obtained aluminum nitride sintered sheet It is particularly preferably used in the present invention because of its improved thermal conductivity and improved translucency. When producing the aluminum nitride powder used in the present invention, a compound corresponding to the sintering aid described below is added to the raw material in advance, and the aluminum nitride powder obtained by firing is obtained in a form containing the sintering aid. It will be done. Such aluminum nitride powder is one in which the components (i) and (ii) of the present invention are blended in advance,
This is one of the preferred usage forms. One of the other components that make up the aluminum nitride composition of the present invention is a binder. The binder used in the present invention is an organic polymer compound that decomposes at temperatures below 1400°C. The aluminum nitride composition of the present invention is generally sintered at a temperature of 1600 to 2000°C, for example via an aluminum nitride green sheet,
It is suitably used as a sintered aluminum nitride sheet. In this case, if a large amount of decomposition residue of the binder remains in the sintered body, it becomes difficult to obtain the desired physical properties of the sintered body, such as high strength, high thermal conductivity, or translucency. According to the findings of the present invention, the binder having the above requirements does not substantially remain in the sintered body, or even if it remains, the amount is such that it does not impair the desired physical properties of the sintered body. It is necessary to select the type and process it. Binders that are generally used for molding ceramic powders are not particularly limited and may be used in the present invention, but in general, binders that decompose in a temperature range of 1400° C. or lower are preferred as determined by thermogravimetric analysis (TG). More preferably, a binder is selected whose decomposition residue is 5% by weight or less based on the binder. More specific examples of binders preferably used in the present invention include polyvinyl butyral, polymethyl methacrylate, cellulose acetate butyrate, nitrocellulose, polyacrylic acid ester, polyvinyl alcohol, methylcellulose, hydroxymethylcellulose, and Oxygen-containing organic polymers such as polyethylene oxide, other hydrocarbon-based synthetic resins such as petroleum resins, polyethylene, polypropylene, and polystyrene; polyvinyl chloride; acrylic resins and their emulsions; waxes and their emulsions; and other types of organic polymers Or a mixture of two or more types is used. As mentioned above, the surface of the aluminum nitride powder used in the present invention is inevitably oxidized and has Al--O bonds. Therefore, it is particularly preferable to use the oxygen-containing organic polymer as a binder since it exhibits a strong bonding force based on its excellent chemical affinity with the surface of the aluminum nitride powder. The organic polymer used as the binder is not particularly limited, but generally has a molecular weight of 3,000 to 1,000,000, preferably 5,000 to 1,000,000.
300,000 is more suitable because the above-mentioned molded article, such as a green sheet, is flexible and tough and can be easily handled during various processing. Among the organic polymers, oxygen-containing organic polymers are particularly preferred, and polyvinyl butyler having a molecular weight of 30,000 to 100,000 is most preferred. The amount of binder used varies depending on the type of binder and the type of solvent described below, and also depends on the application of the aluminum nitride composition, such as the thickness, strength, and processability of the aluminum nitride green sheet, as well as the sintering of the green sheet. Although it cannot be definitively defined as it varies depending on the physical properties required for the aluminum nitride sintered sheet obtained by the process, generally aluminum nitride powder 100
0.1 to 30 parts by weight, preferably 2.5 to 30 parts by weight
The amount may be selected from the range of 15 parts by weight, more preferably from 4 to 10 parts by weight. One of the other components constituting the aluminum nitride composition of the present invention is expressed by the general formula _n MO・Al ₂ O ₃・_o H ₂ O (where M is an alkaline earth metal and m is 1
or more, and n is a number of 0 or more. ) is a sintering aid made of an aluminate salt. Although m may be a number of 1 or more, the larger m is, the greater the effect of the sintering aid is, and the higher the purity of the obtained aluminum nitride sintered body. Therefore, in the present invention, it is preferable that m is 1.5 or more, and an aluminate salt in which m is 2 or more is more preferably used. Further, the aluminate used in the present invention may be anhydrous or may contain water of crystallization. Specific examples of aluminate salts preferably used in the present invention are as follows. For example, CaO・Al ₂ O ₃ , 5CaO・3Al ₂ O ₃ , 12CaO・
Calcium aluminate or hydrate thereof such as 7Al ₂ O ₃ , 3CaO・Al ₂ O ₃ ; Barium aluminate or its hydrate such as 3BaO・Al ₂ O ₃ ; 3SrO・Al ₂ O ₃ ,
Examples include strontium aluminate such as 3SrO.Al ₂ O ₃ .6H ₂ O or its hydrate. The smaller the particle size of the aluminate used in the present invention, the more effective it is as a sintering aid. Therefore, the average particle diameter is preferably 10 μm or less, more preferably 5 μm or less. Generally, it is preferable to use an aluminate having an average particle size of 0.1 to 10 μm, more preferably 0.1 to 5 μm. The amount of the sintering aid used in the present invention varies depending on the properties required of the sintered body and cannot be absolutely limited, but it is generally 0.01 to 5 parts by weight, preferably 0.1 to 100 parts by weight of aluminum nitride powder. ~4
You can choose from a range of parts by weight. Since the amount of these additives varies depending on the oxygen content, impurity content, particle size, etc. in the aluminum nitride powder, the appropriate amount to be used may be determined in advance according to these properties. The aluminum nitride composition of the present invention is prepared by mixing the aluminum nitride powder, binder, and sintering aid in the proportions described above, as well as adding and mixing a deflocculant, a plasticizer, etc. as necessary. It is not intended to be limiting and is often used as a preferred embodiment. For example, when the aluminum nitride powder, binder, and sintering aid of the present invention are dispersed and mixed in a solvent as described in detail later, a deflocculant is often used to promote the dispersion. is a preferred embodiment. As the deflocculant, any compound known to be generally used in molding ceramic powder may be used without particular limitation. Specific examples of typical deflocculants that are generally suitably used include glycerin or sorbitol esters of fatty acids such as glycerin trioleate and sorbitan trioleate; natural fish oil; nonionic synthetic surfactants; higher fatty acids ; benzenesulfonic acid, etc.
The amount of these deflocculants to be used varies depending on the type of deflocculant, the type of the mixed system to be added, etc., and cannot be absolutely limited, but in general, it is preferably 0.01 to 5 parts by weight per 100 parts by weight of aluminum nitride powder. It is preferable to select from the range of 0.1 to 3 parts by weight. Although the peptizer may be mixed in any order, generally the aluminum nitride powder and the sintering aid are mixed in advance with the peptizer in a dispersion medium, and then the binder or the plasticizer described later is added. It is preferable to add and mix them to prepare a slurry. Further, the plasticizer is used for the purpose of imparting flexibility to a specific molded product when the aluminum nitride composition of the present invention is processed into a specific molded product. The plasticizer is not particularly limited, and any plasticizer known to be used for the above purpose in molding general ceramic powder can be used. Typical examples that are particularly preferably used include generally polyethylene glycol and its derivatives; phthalate esters such as dimethyl phthalate, dibutyl phthalate, butylbenzyl phthalate and dioctyl phthalate; stearic acid such as butyl stearate. Esters; Tri-cresol phosphate; Tri-N
-butyl phosphate; glycerin, etc.
The amount of these plasticizers added varies depending on the type of binder, the properties of aluminum nitride, the type and amount of solvent used, etc., and cannot be absolutely limited, but in general, it is 15 parts by weight or less per 100 parts by weight of aluminum nitride. Preferably 0.4 to 15 parts by weight, more preferably 3 to 10 parts by weight
It may be used by appropriately selecting from the range of parts by weight. The usage mode of the aluminum nitride composition of the present invention will be explained below. When used, it is generally preferable to use it in a form dispersed in a dispersion medium. The role of the dispersing medium is generally to disperse the aluminum nitride powder and the sintering aid, and also to dissolve the binder or optionally used plasticizer to form a uniform slurry. After forming the slurry into a specific shape, such as a sheet, the solvent is preferably substantially removed by drying and does not remain in the aluminum nitride molded product, such as a green sheet. Therefore, the dispersion medium, ie, the solvent, is not particularly limited as long as it satisfies the above-mentioned requirements for dispersibility, solubility, and drying properties, but it is generally preferable to select a non-aqueous solvent. Typical solvents that are particularly preferably used include, for example, acetone,
Ketones such as methyl ethyl ketone and methyl isobutyl ketone, alcohols such as ethanol, propanol and butanol, aromatic hydrocarbons such as benzene, toluene and xylene, or halogenated hydrocarbons such as trichloroethylene, tetrachloroethylene and bromochloromethane.
It is preferable to use one species or a mixture of two or more species. The amount of solvent used is also not particularly limited, but if the amount of solvent is too large, particles of aluminum nitride powder and sintering aid will tend to settle and separate during storage, molding, or drying of the slurry, and if it is too small, the sheet-like Since molding becomes difficult, an appropriate amount may be selected and used in advance. In general, the amount of the solvent depends on the type and the type and amount of the binder and plasticizer, but 30 parts by weight per 100 parts by weight of aluminum nitride powder.
It is preferable to select the amount within the range of 100 parts by weight. The mixing conditions for the aluminum nitride composition of the present invention are not particularly limited, and the mixing may be carried out at room temperature and normal pressure, and the mixing device is explained based on the mixing mode of the raw materials for producing the aluminum nitride powder in order to prevent the mixing of impurity components. It is preferable to choose the material as shown above or choose one covered with plastic. Most generally, it is preferable to use a mill that has a built-in spherical object, rod-like object, or the like. The above-mentioned mixture is generally used as a viscous paint-like slurry called slurry, which is easy to handle during molding. The aluminum nitride composition obtained as described above, that is, the (i) aluminum nitride powder, (ii) binder, and (iii) sintering aid, or if necessary, a plasticizer, peptizer, etc. are mixed in a solvent. It is generally turned into a slurry. This slurry is formed into a sheet on a film made of a synthetic resin such as polyethylene, polypropylene, polyester, polyamide, polyvinyl chloride, etc. using a sheet molding machine such as a doctor blade type sheet molding machine. Next, the sheet-like molded product is dried by scattering the solvent at a temperature between room temperature and the boiling point of the solvent to form a so-called aluminum nitride green sheet. The aluminum nitride green sheet generally has a glossy appearance, is flexible, and has strong properties against bending. The aluminum nitride green sheet already has a tensile strength of 25 kg/cm ² or more. The above aluminum nitride green sheet can be used as it is for the production of a sintered sheet as described below, but generally the above-mentioned binder, plasticizer, etc. It is preferable to carry out the thermal decomposition treatment at a temperature at which the agent, deflocculant, etc. are decomposed, generally, for example, from 300 to 1,400°C, preferably from 500 to 1,000°C. The aluminum nitride green sheet or the sheet subjected to the above heat treatment is then subjected to a sintering process. The sintering process is not particularly limited, and any known sintering method used for nitrides may be used as is. Generally, sintering may be carried out at a temperature of 1,600 to 2,100° C. under normal pressure, in an inert atmosphere, for example, in a nitrogen atmosphere.
The pressure during the sintering is generally normal pressure, but a sintering furnace maintained under a certain degree of pressure with an inert gas may also be used. Further, the time required for sintering varies depending on various conditions such as the thickness of the sheet material to be sintered and the sintering temperature, and cannot be absolutely limited, but it may generally be selected from a range of 30 minutes to 24 hours.
It is preferable that appropriate ranges of these conditions be determined in advance according to various conditions prior to implementation. The sintered sheet obtained by the above sintering process generally has a sintered density of 2.7 g/cm 3 or more, preferably 2.9 g/cm ³ or more.
cm ³ More preferably 3.0 g/cm ³ or more.
Additionally, the sheet generally has a side length of at least 5 mm.
With the above steps, a product having a thickness in the range of 0.05 to 10 mm is obtained. These sintered sheets form excellent sheet-like products with a bending strength of at least 20 kg/mm ² . [Effect] The aluminum nitride sintered sheet obtained by the above method using the aluminum nitride composition of the present invention as a raw material has a high oxygen content even though aluminate, which is an oxide, is added. The oxygen content is lower than the oxygen content of the raw material aluminum nitride powder. That is, a highly purified aluminum nitride sintered sheet, for example, an aluminum nitride sintered sheet with an oxygen content of 1.5% by weight or less, more preferably 1.2% by weight or less, can be obtained. These sintered aluminum nitride sheets have extremely good thermal conductivity due to their high purity, and are generally 120 W/m・k or more, preferably
A thermal conductivity of 140W/m・k or more can be obtained. Furthermore, the sintered sheet can be produced by controlling the amount of impurities mixed in the aluminum nitride powder used as the raw material.
It can be made into a translucent sheet. Therefore, the aluminum nitride sintered sheet made from the aluminum nitride composition of the present invention is an industrially extremely useful material as a heat dissipation board for electronic equipment, an electronic circuit board, a heat dissipation material, and an insulating material. EXAMPLES In order to explain the present invention more specifically, the present invention will be described below with reference to Examples, but the present invention is not limited to these Examples. Reference Example 1 600 g of calcium carbonate with an average particle size of 2.1 μm and 200 g of alumina with an average particle size of 0.6 μm were dry mixed for 18 hours using an alumina pot and a ball.
The mixture was calcined at 1350°C for 4 hours. The reactants were ground using an alumina pot and ball. The reaction was completed by repeating calcination and pulverization three times. This reaction product was pulverized using a diet mill (alumina lining) to obtain a powder with an average particle size of 1.4 μm. This powder was found to be single-phase 3CaO.Al ₂ O ₃ by X-ray examination. Example 1 (i) Blend Reference Example 1 was added as a sintering aid to 100 parts by weight of aluminum nitride powder having the composition shown in Table 1 containing 80% by volume of particles with an average particle size of 1.42 μm and 3 μm or less.
2.5 parts by weight of 3CaO・Al ₂ O ₃ prepared above, 9.0 parts by weight of polyvinyl butyral with a molecular weight of 30,000 to 34,000 as a binder, 5.0 parts by weight of dioctyl phthalate as a plasticizer, and 1.2 parts by weight of sorbitan trioleate as a peptizer. 75 parts by weight of a toluene-ethanol-iso-propanol mixed solvent (mixed weight ratio toluene/ethanol/iso-propanol = 55/35/10) as described below to prepare a slurry. The combustion decomposition curve of the above polyvinyl butyral was previously measured in air using thermogravimetric analysis (TG), and it was found that combustion decomposition started at about 200℃ and reached approximately 200°C.
It was confirmed that substantially no residue remained after finishing at 600°C. Table 1 Aluminum nitride powder analysis values AlN content 98.0% Element content Mg <5 (PPM) Cr 21 ( ) Si 81 ( ) Zn 9 ( ) Fe 14 ( ) Cu <5 ( ) Mn 5 ( ) N 25 ( ) Ti <5 ( ) Co <5 ( ) Al 64.8 (wt%) N 33.5 ( ) O 1.0 ( ) C 0.04 ( ) (ii) Mixing Mixing operations and procedures was done as follows. In other words, a nylon-coated steel ball with a diameter of 20 mm is placed in a nylon pot with an internal volume of 10 mm, and the inner volume of the pot is approximately 50 mm.
%, and then the above weight parts of aluminum nitride powder, 3CaO.Al ₂ O ₃ and sorbitan trioleate, and 60 weight parts of the above solvent were added and mixed in a ball mill at a rotation speed of 35 rpm for 24 hours.
Thereafter, the above weight parts of polyvinyl butyral and dioctyl phthalate and 15 weight parts of the above solvent were added to the pot, and the mixture was further mixed for 24 hours. The resulting slurry was white paint-like with a viscosity of 2800 cps. (iii) Defoaming and desolvation The slurry obtained by the above mixing is transferred to a vacuum container with an internal volume of 4 equipped with a stirrer, and while stirring, the pressure is gradually reduced from 1 atm to 30 to 40 Torr, and the slurry is mixed into the slurry during the mixing. Removed air bubbles (defoaming). Next, while stirring, the vacuum container was evacuated and maintained at 20 to 40 Torr to remove a portion of the solvent by evaporation (desolvation). The amount of solvent removed in this desolvation operation was 20 parts by weight based on 100 parts by weight of aluminum nitride powder. As a result, a white viscous slurry with a viscosity of 20,000 cps was obtained. (iv) Molding Using a doctor blade type sheet molding machine, the obtained slurry is poured into a sheet onto a polyester film whose surface has been coated with silicone resin and subjected to mold release treatment, and then the sheet is molded at room temperature. After drying by evaporating the solvent for 1 hour and then at 50° C. for 4 hours, the sheet-like material was peeled from the polyester film to produce an aluminum nitride green sheet with a width of about 250 mm and a thickness of about 1 mm. This aluminum nitride green sheet has a white, glossy appearance, and is flexible and strong against bending. Punch out a test piece from an aluminum nitride sheet using a die and a punching machine,
When a tensile test was performed using an autograph,
The tensile strength was 25 Kg/cm ² and the elongation was 0.4. Further, the density was 2.04 g/cm ³ . (v) Degreasing and sintering 5cm of the above aluminum nitride green sheet
It was punched into a square plate shape of 5 cm, heated in an electric furnace at 650°C for 3 hours in an air atmosphere of 1 atm to burn and decompose the binder, plasticizer and deflocculant, and remove the aluminum nitride. A square plate was obtained (degreased). This square plate was placed in a graphite dish whose inner wall was coated with boron nitride, and heated to 1200℃ for 2 hours under a nitrogen flow of 1 atm.
The temperature was raised from 1200°C to 1800°C at a temperature increase rate of 15°C/min, and after being held at 1800°C for 4 hours, it was cooled (sintering). The obtained aluminum nitride sintered sheet was a translucent body measuring 4.1 mm x 4.1 mm and 0.8 mm thick, and had a density of 3.25 g/cm ³ . The thermal conductivity of this sintered sheet was measured using a laser flash method thermal constant measuring device (PS-7) manufactured by Rigaku Denki and was found to be 163 W/m·k. The bending strength of this sintered sheet is 40Kg/ ^mm2 , and the oxygen content measured by activation analysis is 0.28% by weight.
The transmittance of light at 5.5 μm was 38% when processed and polished to a thickness of 0.5 mm. Example 2 Aluminum nitride was prepared as follows using several kinds of aluminum nitride powders with different oxygen contents, calcium aluminate of various particle sizes as a sintering aid, and polyvinyl butyral with a molecular weight of 30,000 to 34,000 as a binder. Table 2 shows the results of producing the sintered sheet.
Shown below. (i) Blend Aluminum nitride powder 100 parts by weight Calcium aluminate (amount shown in Table 2) Polyvinyl butyral 12 parts by weight Dibutyl phthalate 6 Glycerin monooleate 1.5 Toluene (50% by weight) Iso-propanol (35% by weight) n-Butanol (15% by weight) 80 (ii) Mixing The above mixture composition was mixed as follows. In other words, a nylon-coated steel ball with a diameter of 20 mm is placed in a nylon pot with an internal volume of 10, in an amount that accounts for 50% of the pot's internal volume, and the entire amount shown in (i) is added to the pot, and the mixture is rotated. Mixed in a ball mill for 40 hours at several 35 rpm. The viscosity of the obtained slurry is 2000~
It was in the range of 3500cps. (iii) Defoaming and solvent removal Defoaming and solvent removal were performed using the same equipment and operation as in Example 1. The amount of desolvation is in the range of 20 to 25 parts by weight per 100 parts by weight of aluminum nitride powder,
The viscosity of the obtained white viscous slurry is 21000 ~
It was 26000cps. (iv) Molding The above slurry was prepared in the same manner as in Example 1, with a tensile strength of 30 to 35 Kg/cm ² , an elongation of 0.5 to 0.7, and a density of
An aluminum nitride green sheet with a weight of 1.98 to 2.23 g/cm ³ was produced. (v) Degreasing and sintering The aluminum nitride green sheet obtained above is
A square plate of 50 mm x 50 mm was punched out, and this square plate was placed in a graphite dish whose inner wall was coated with boron nitride and set in an electric furnace. Degreasing was carried out under reduced pressure of 0.1 Torr by increasing the temperature from room temperature to 1100°C at a rate of 2°C/min. After that, it was heated from 1100℃ to 1850℃ in the same electric furnace for 15 days.
The temperature was raised at a rate of 180°C/min, maintained at 180°C for 4 hours, and then cooled. The obtained aluminum nitride sintered sheet was a translucent body measuring 4.0 to 4.2 mm square and 0.8 mm thick.
Table 2 shows the physical properties of the sintered sheet.

[Table] Reference Example 2 600 g of barium carbonate with an average particle size of 1.8 μm and 100 g of alumina with an average particle size of 0.6 μm were dry mixed for 18 hours using an alumina ball and pot. The mixture was calcined at 1550°C for 5 hours. The reactants were ground using an alumina ball and pot. The reaction was completed by repeating calcination and pulverization three times. This reaction product was pulverized using a diet mill (alumina lining) to obtain a powder with an average particle size of 1.6 μm. This powder was found to have a single phase composition of 3BaO.Al ₂ O ₃ by X-ray examination. Example 3 The same aluminum nitride powder used in Example 1, and 3BaO prepared in Reference Example 2 as a sintering aid.
An aluminum nitride green sheet and an aluminum nitride sintered sheet were produced as follows using Al ₂ O ₃ and polyvinyl butyral having a molecular weight of 50,000 to 60,000 as a binder. (i) Blend Aluminum nitride powder 100 parts by weight 3BaO・Al ₂ O ₃ 2 parts by weight Polyvinyl butyral 10 〃 Butylbenzyl phthalate (50% by weight) Dioctyl phthalate (50% by weight) 4 〃 Glycerin trioleate 1 〃 Toluene (60% by weight) %) Ethanol (35% by weight) n-Butanol (5% by weight) 80 〃 (ii) Mixing In the same bowl and pot as used in Example 1, aluminum nitride powder, 3BaO・Al ₂ O ₃ and glycerin trioleate were added. Total amount and part of solvent (60
parts by weight) and mixed in a ball mill for 24 hours.
Then, add the entire amount of polyvinyl butyral, butylbenzyl phthalate, and dioctyl phthalate to the same pot, and add the remaining amount of the solvent (20 parts by weight).
Mixed for 24hr. The viscosity of the slurry obtained is
It was 3200cps. (iii) Defoaming and solvent removal The same procedure as in Example 1 was carried out to obtain a white viscous slurry with a viscosity of 28,000 cps. (iv) Forming An aluminum nitride green sheet was produced from the above slurry in the same manner as in Example 1. The tensile strength of this green sheet is 27Kg/cm ² and the elongation rate is 0.35.
Further, the density was 2.12 g/cm ³ . (v) Degreasing and sintering Sintering was performed in the same manner as in Example 1, except that it was held at 1800°C for 6 hours, and the size was 4.2 mm x 4.2 mm, and the thickness was 0.8 mm.
Thus, a translucent aluminum nitride sintered sheet with a density of 3.24 g/cm ³ was obtained. This sintered sheet had a thermal conductivity of 145 W/m·k and an oxygen content of 0.37% by weight. Example 4 Aluminum nitride powders with various particle sizes and oxygen contents shown in Table 3, and various particle sizes as sintering aids
Mixing, defoaming, demolding, molding, and degreasing were carried out under the same conditions as in Example 3 except for using 3BaO・Al ₂ O ₃ .
Firing was performed to produce a sintered aluminum nitride sheet. The results are shown in Table 3.

[Table] Reference example 3 550g of strontium carbonate with an average particle size of 3.2μm
and 100 g of alumina having an average particle size of 0.6 μm were dry mixed for 18 hours using an alumina ball and pot. The mixture was calcined at 1600°C for 4 hours. The reactants were ground using an alumina ball and pot. The reaction was completed by repeating calcination and pulverization three times. This reaction product was pulverized using a diet mill (alumina lining) to obtain a powder with an average particle size of 1.4 μm. This powder had a single phase composition of 3SrO.Al ₂ O ₃ based on X-rays. Example 5 The same aluminum nitride powder used in Example 1, and 3SrO prepared in Reference Example 3 as a sintering aid.
Using Al ₂ O ₃ and a methacrylic acid ester copolymer (ethyl methacrylate/methyl methacrylate = 72/28) with a molecular weight of 50,000 to 90,000 as a binder, an aluminum nitride green sheet and then an aluminum nitride sintered sheet were prepared as follows. was created. (i) Blend Aluminum nitride powder 100 parts by weight 3SrO・Al ₂ O ₃ 5 〃 Methacrylic acid ester copolymer 12 〃 Dioctyl phthalate 3 〃 Sorbitan trioleate 0.8 〃 Toluene (50% by weight) Methyl ethyl ketone (50% by weight) 70 〃 ( ii) Mixing Pour half of the solvent (35 parts by weight) into a dispersion mixer with an internal volume of 5 and a stirrer, and add all of the aluminum nitride powder, 3SrO・Al ₂ O ₃ and sorbitan trioleate while stirring, and then add the methacrylic ester as well. The polymer was slowly added and dissolved. Next, the entire amount of dioctyl phthalate was added, and the remaining amount of the solvent (35 parts by weight) was added, and stirring was continued for 30 minutes to disperse or dissolve the ingredients to prepare a slurry. This slurry was transferred to the ball mill used in Example 1, and mixed in the ball mill for 24 hours at a rotation speed of 35 rpm. The resulting slurry had a viscosity of 1200 cps. (iii) Defoaming and solvent removal This was carried out in the same manner as in Example 1. The amount of solvent removed is 25 parts by weight per 100 parts by weight of aluminum nitride,
The viscosity of the resulting viscous slurry was 18,000 cps. (iv) Molding An aluminum nitride green sheet with a width of 300 mm and a thickness of 1.1 mm was obtained in the same manner as in Example 1. The strength of this green sheet is 18Kg/cm ² and the density is 2.18g/cm ³
It was hot. (v) Degreasing and sintering the above aluminum nitride green sheet to 65mm
A square plate of 65 mm x 65 mm was punched out, and this square plate was placed in a graphite dish whose inner wall was coated with boron nitride and set in an electric furnace. Next, the temperature was raised from room temperature to 1000°C at a rate of 2°C/min under nitrogen flow at 1 atm. Then, in the same electric furnace under a nitrogen atmosphere of 1 atm.
The temperature was raised from 1000°C to 1900°C at a rate of 15°C/min, maintained at 1900°C for 6 hours, and then cooled. The resulting aluminum nitride sintered sheet is 53mm x 53mm thick.
It was a 0.85 mm translucent body with a density of 3.25 g/cm ³ . The thermal conductivity of this sintered sheet is 156W/
m·k, and the oxygen content was 0.26% by weight. Example 6 Example 5 except that aluminum nitride powders with various particle sizes and different oxygen contents and 3SrO.Al ₂ O ₃ with various particle sizes as sintering aids were used as shown in Table 4.
Aluminum nitride green sheets and sintered sheets were produced under the same conditions as described above. The results are shown in Table 4.

【table】

Claims (1)

[Scope of Claims] 1 (i) aluminum nitride powder, (ii) a binder made of an organic polymer compound that decomposes at a temperature of 1400°C or less, and (iii) general formula _n MO・Al ₂ O ₃・_o H ₂ O [However, M is an alkaline earth metal, m is 1
or more, and n is a number of 0 or more. ] The binder consists mainly of a sintering aid consisting of an aluminate salt shown in
0.1 to 30 parts by weight per 100 parts by weight, and the sintering aid is 0.01 parts by weight per 100 parts by weight of aluminum nitride powder.
An aluminum nitride composition containing ~5 parts by weight. 2. The aluminum nitride composition according to claim 1, wherein the aluminum nitride powder has an oxygen content of 3.0% by weight or less. 3. The aluminum nitride composition according to claim 1, wherein the aluminum nitride powder has an average particle size of 5 μm or less. 4. The aluminum nitride composition according to claim 1, wherein the aluminum nitride powder contains 0.5% by weight or less of a metal compound as an impurity. 5. The aluminum nitride composition according to claim 1, wherein the binder is an oxygen-containing organic polymer. 6 Molecular weight of oxygen-containing organic polymer is 3000~
1,000,000. The aluminum nitride composition according to claim 5.