JP2773416B2 - Aluminum nitride sintered body and method for producing the same - Google Patents

Description

The present invention relates to an aluminum nitride sintered body and a method for producing the same, and more particularly, to a dense and high-heat method in which fine particles are dispersed in aluminum nitride crystals. The present invention relates to an aluminum nitride sintered body having high conductivity, high strength and excellent light shielding properties, and a method for producing the same.

[Prior art] The recent technological progress centered on the electronics industry is remarkable,
The properties required for the materials used are becoming more stringent.
For example, in semiconductors, the amount of heat generation and the heat generation density are rapidly increasing due to the increase in the degree of integration and processing speed, and the heat radiation characteristics required for the substrate material are becoming severe. For this reason, the conventional Al ₂ O ₃ substrate has low thermal conductivity and insufficient heat dissipation, and cannot cope with an increase in the heat generation of the semiconductor. For this reason, beryllium oxide (BeO) can be cited as a substrate material in place of Al ₂ O ₃ , but BeO has the drawback of being toxic and difficult to handle. Therefore, new materials are required.

In the automotive field, in order to improve engine efficiency due to the need to protect the global environment, not only weight reduction of the vehicle body but also weight reduction and high efficiency of the engine system are pursued.
Particularly, in the high heat portion, a material having a light weight, a high heat resistance, a high strength and a high thermal conductivity is required, and a conventional metal material can no longer cope therewith, and a ceramic material is being studied. However, none of the conventional ceramic materials can satisfy both strength and thermal conductivity at the same time.

On the other hand, aluminum nitride (AlN) is a substance having high thermal conductivity and high electrical insulation, and is toxic and has abundant resources. Therefore, if a sintered body can be obtained at low cost, the above-mentioned required characteristics can be satisfied. Therefore, research and development has been carried out for a long time. AlN has poor sinterability, and it is difficult to make AlN alone dense. Therefore, a sintering aid is added. For example,
As shown in -71575, compounds of one or more metals from the group consisting of alkaline earth metals, yttrium and lanthanum group metals have been used. Research and development to make AlN's original material properties effective and useful
On the premise of such a dense sintered body, it has been performed in the following three directions. The first direction is intended to obtain a high-strength material and use it as a structural material, and to achieve a mechanical strength improvement by forming a fibrous structure. For example, according to Japanese Patent Publication No. 56-36153, a high-strength AlN sintered body is obtained by adding SiO ₂ or a silicate mineral. However, in this case, high strength was achieved at the expense of thermal conductivity, and it was hard to say that the characteristics of the AlN main body were fully exhibited.

The second direction is a development direction that prioritizes enhancing thermal conductivity. For example, Japanese Patent Application Laid-Open No.
By using a high-purity AlN raw material powder, a sintered body having high thermal conductivity is obtained. This sintered body has an absorption coefficient of infrared light having a wavelength of 6 μm of about 20 cm ⁻¹ and a thermal conductivity exceeding 60 W / m · K. Further, JP-A-63-3038
In 63, a higher thermal conductivity is obtained by extending the sintering time and decreasing the amount of sintering aid added. In this case, a light-transmitting material having a thermal conductivity of 200 W / m · K or more and an absorption coefficient of light at a wavelength of 500 nm of 50 cm ⁻¹ or more is obtained. However, although the AlN sintered bodies obtained in this development direction have excellent thermal conductivity,
The material strength was low due to remarkable coarsening of the lN particles, and the reliability was practically low. Further, it is said that it is not preferable as a material for a semiconductor package, for example, because of its light transmitting property.

The third direction is a direction in which a specific compound is added to improve the second direction to provide a light-shielding property, or to improve a metallizing property. For example, JP 62
According to -153173, a colored AlN that can be sintered at a low temperature, is dense and has high thermal conductivity is obtained by adding elements of Groups 4a, 5a, 6a, 7a and 8 of the periodic table. However, these materials have a thermal conductivity of at most about 100 W / m · K and a flexural strength of at most about 60 kg / mm ² . JP-A-61-270262
In order to improve the metallization strength,
Added borides, nitrides and carbides of group 4a, 5a and 6a elements
Although an AlN sintered body is disclosed, the sintered body is present at the grain boundary of these added AlN particles to improve metallization. However, its thermal conductivity is
It is as low as about 120 W / m · K, and there is no description about its mechanical strength and light transmittance. JP-A-2-124772 discloses AlN
With Ti, Zr, Hf, V, Nb, Ta, Co, Mo, W, M
An AlN sintered body containing at least one metal element selected from n, Fe, Co, Ni, Nd, and Ho and having a thermal conductivity of 150 W / m · K or more is disclosed. This sintered body has a light-shielding property and a high thermal conductivity, but has a low level of strength.

In other words, the research and development direction of the conventional AlN sintered body is focused on pursuing high thermal conductivity by reducing impurities, mainly oxygen, in the sintered body as much as possible.
In some of them, the mechanical strength has been improved, and the grain boundary phase has been improved by studying the type of additive to improve the metallized strength and to improve the coloring.
Furthermore, no attempt has been made to improve mechanical strength and light-shielding properties as well as thermal conductivity.

[Problems to be Solved by the Invention] The development direction of AlN sintered bodies up to now is
Of AlN has not been able to fully utilize the inherent properties of AlN, and it cannot be said that the properties required for practical use are necessarily satisfied. In the situation. That is, the object of the present invention is to
An object of the present invention is to provide aluminum nitride which is dense, has high thermal conductivity, high strength, and is excellent in light-shielding properties.

[Constitution of the Invention] (Means and Actions for Solving the Problems) The present inventors have conducted experiments on AlN sintered bodies, including AlN raw material powder, in order to achieve the above-mentioned object, and as a result, have found a novel microstructure. Of the present invention and completed the present invention.

In other words, by forming an AlN sintered body with a unique structure structure in which a fine compound having a specific crystal structure is dispersed in AlN particles, it has excellent thermal conductivity and mechanical properties, and also has excellent light shielding properties It was found that those having the following were obtained. Generally, AlN belongs to a hexagonal system and has a wurtzite type crystal structure. In the present invention, a compound belonging to a different crystal system is finely dispersed in the aluminum nitride crystal lattice without forming a solid solution in the crystal lattice. The preferred crystal system of the compound to be dispersed is a cubic system,
More preferably, it has a Cl structure. By doing so, it is possible to enhance not only the thermal conductivity and the light-shielding property but also especially the bending strength. Incidentally crystals ₂ such BeO or TiB the same crystal system as AlN is hardly distributed to the AlN particles and not as a result be sufficient improvement in the characteristics. By doing so, it is possible to enhance not only the thermal conductivity and the light-shielding property but also especially the bending strength.

That is, the aluminum nitride sintered body provided by the present invention has an average particle diameter of 1/5 or less of aluminum nitride particles in aluminum nitride particles having a hexagonal wurtzite structure and an average particle diameter of 1 μm or more. Compound particles having a structure other than a wurtzite structure are finely dispersed without forming a solid solution in an aluminum nitride crystal lattice. In particular, it is desirable that the finely dispersed particles be a compound having a NaCl structure.

In the aluminum nitride sintered body of the present invention, the relationship between the particle size of AlN particles and that of dispersed compound particles is one of the most important control factors for achieving the above object, and is ultimately obtained. In the sintered body to be prepared, the average particle size of the dispersed compound particles is 1/5 or less of that of the AlN particles. If the average particle size of the compound particles to be dispersed exceeds 1/5 that of the AlN particles, the effect of improving the mechanical strength by the above-described dispersed particles is particularly reduced. The effect increases as the average particle size of the dispersed particles decreases. In the sintered body of the present invention, the average particle size of the dispersed particles is desirably 0.3 μm or less. The average particle size of the AlN particles is 1 μm or more. This is because, as the AlN particles become finer, the mechanical strength of the sintered body increases, but the incorporation of the finely dispersed particles becomes insufficient, and the amount of the dispersed particles protruding into the AlN grain boundaries increases, which is not preferable.

That is, in the aluminum nitride sintered body of the present invention, usually finely dispersed particles are mostly present in AlN particles,
Also, most of the AlN particles have fine dispersed particles, but the majority of the dispersed particles are in the AlN particles, and the rest is desirably in the AlN particle size, and the ratio of the dispersed particles present in the AlN particles Is more preferable. If the dispersed particles are dispersed in the AlN particles, the decrease in the thermal conductivity is suppressed to a small extent, and the contribution to the increase in the light shielding property and the improvement in the strength of the sintered body is increased.

The compound particles finely dispersed in the aluminum nitride particles of the present invention include Ti, Zr, Hf, V, Nb, Ta, Mo, W, Fe, C
Preferably, it is a compound of at least one element selected from the group consisting of o and Ni, and its addition amount is preferably 0.01 to 30% by weight in terms of element. Compound particles are T
The compound is preferably a compound of at least one element selected from the group consisting of i, Zr, Hf, V, Nb, Ta, Mo, W, Fe, Co, and Ni. The effect is not limited to the above. In particular, these elements have a large light-absorbing effect and greatly contribute to improving the light-shielding property. Further, these metal elements may be metals or compounds such as oxides, carbides, nitrides, and the like, but they need to be separated and dispersed to the last extent instead of being dissolved in the AlN crystal lattice. That is, solid solution of AlN particles in the lattice must be avoided because it greatly reduces the thermal conductivity of AlN, and most of the above metal elements are substituted or interstitial in the lattice of AlN particles. It must be not dissolved. The dispersed particles are preferably a compound containing an element selected from Ti, Zr, Hf, V, Nb, and Ta. These compounds are compounds having a NaCl structure and exist, for example, in the form of nitrides, carbides, borides, oxides or solid solutions thereof. Particularly, in the case of a compound mainly composed of a nitride, the effect aimed at by the present invention is large. The dispersed particles are contained in the sintered body in the range of 0.01 to 30% by weight, preferably 0.01 to 5.0% by weight, in terms of the element. If the content is too large, the electrical insulation property and the compactness decrease, and it is necessary to keep the content within these limits. If the dispersed particles are fine, the desired effect of the present invention can be sufficiently obtained in an amount of up to 5.0% by weight. In particular, it is possible to obtain an aluminum nitride sintered body having sufficient light-shielding properties and mechanical strength at a content of up to 1.0% by weight, and having both high thermal conductivity and electrical insulating properties.

Also, a sintering aid can be used to improve the sinterability of the AlN particles. As the sintering aid, known alkaline earth and rare earth element compounds are preferably used, and these are not dissolved in the AlN crystal lattice in the sintered body, and the Al and O contained in the AlN powder are not dissolved. And forms a compound with the AlN grain boundary. If the amount of the sintering aid is small, the thermal conductivity decreases and the sintering density does not easily increase. On the other hand, if it is too large, the thermal conductivity of the sintered body is rather lowered, and the surface roughness of the surface of the sintered body is deteriorated. Therefore, the amount of addition of these sintering aids is 0.01 to 10% by weight in terms of the oxide,
Preferably, it is in the range of 0.01 to 3.0% by weight. Examples of the added form include oxides, carbonates, hydroxides, stearic acid compounds, and alkoxides. These are mainly present as oxides in the sintered body, and often form a compound with Al ₂ O _{3 on the} surface of the AlN powder.

Next, the characteristics of the obtained sintered body will be described. The sintered body of the present invention has a transverse rupture strength of 30 kg / mm ² or more. Note that the bending strength in the present invention is obtained by bending a plate-shaped specimen having a width of 4 mm x a thickness of 0.635 mm by three points at 20 mm.
It is obtained by measuring in span. By selecting the preferred production conditions, 50 kg / mm ² or more, further 80kg
It is also possible to obtain strengths exceeding / mm ² . Such high-strength ones have, for example, an average particle size of AlN particles of 5 μm.
Below, and that of finely dispersed particles as 0.3 μm or less,
The majority of these dispersed particles are dispersed in AlN particles, and the rest is AlN
It can be obtained by having it also at the grain boundaries. It is considered that the reason for the development of such high strength is that the growth of AlN particles is appropriately suppressed, and the synergistic effect of strengthening the AlN particles themselves by dispersion and strengthening with the grain boundaries is provided.

The light absorption coefficient of the aluminum nitride sintered body of the present invention is:
It is 50 cm ^-1 or more at a light wavelength of 500 nm, and is colored black, brown, or the like, and exhibits light-shielding properties. The absorption coefficient of the present invention is 0.
It measures with a spectrophotometer using a 5 mm plate specimen.
The absorption coefficient was ^simply calculated as I = I0e−μt. Here, I0 is the intensity of the incident light I is the intensity of the transmitted light μ is the absorption coefficient t is the thickness of the specimen.

Thus, the dispersed particles, except for the sintering aid, consist of high-purity AlN crystal particles, despite showing high thermal conductivity,
It is considered that the reason why the light absorption coefficient is high as described above is that the light absorption ability of the dispersed particles is high. This is considered to be due to the fact that these particles are finely distributed in the AlN particles and contribute to the scattering and absorption of the incident light more efficiently, together with the absorption effect of the dispersed particles by the elements.

The aluminum nitride sintered body of the present invention has a thermal conductivity of 70 W / m
-K or more, flexural strength 30 kg / mm ² or more, and absorption coefficient of light with a wavelength of 50 nm of 50 cm ^-1 or more. Thermal conductivity is more than 120W / m ・ K, furthermore 150W / m ・ K
From the above, a bending strength of 50 kg / mm ² or more, and more preferably 80 kg / mm ² or more is obtained.

The AlN particles of the sintered body according to the present invention have extremely high purity except for finely dispersed particles, and the amount of impurity elements dissolved in AlN crystal particles is extremely small. Therefore, the lattice constant of AlN is 4.979 ° to 4.983 ° in the C-axis direction and 3.110 in the a-axis direction.
C / a is 1.602 or less in {3.113}. Although the half width is increased due to the effect of finely dispersed particles, the c / a of the lattice constant is small, and it is considered that the solid solution substance in the AlN lattice is extremely small. This is considered to be the reason that the thermal conductivity, the light shielding property, and the mechanical strength can be simultaneously improved.

Next, a method for producing the aluminum nitride sintered body of the present invention will be described.

The first production method of the present invention comprises an aluminum nitride powder and Ti, Zr, Hf having an average particle size of 1 μm or less as dispersed particles.
A compound powder of at least one element selected from the group consisting of V, Nb, Ta, Mo, W, Fe, Co, and Ni, and an organic compound that forms free carbon by heating are released in a subsequent heating step. Mixing the carbon powder in an amount such that the amount of carbon is in the range of 0.01 to 5.0% by weight to form a mixed powder, forming the mixed powder into a molded body, and further forming the molded body in a non-oxidized state containing nitrogen. Sintering at 1600 to 2000 ° C. in a neutral atmosphere. In the step of mixing powder if necessary,
In some cases, a compound serving as a sintering aid is additionally mixed.

In the second production method, aluminum, nitride, Ti, Zr, Hf, V, Nb, Tb having an average particle diameter of 0.3 μm or less are synthesized from a raw material serving as a precursor of aluminum nitride.
a, Mo, W, Fe, Co, a compound of at least one element selected from the group consisting of Ni, and a
Preparing an aluminum nitride synthetic powder containing an amount of an organic compound capable of forming carbon in an amount capable of forming free carbon in a range of 5.0% by weight; forming a molded article by molding the synthetic powder; 1600 in a non-oxidizing atmosphere containing nitrogen
And sintering at 20002000 ° C. If necessary, a compound serving as a sintering aid may be additionally contained in the step of preparing a synthetic powder.

The aluminum nitride raw material powder used in the first method is usually of high purity. The synthetic powder mainly composed of aluminum nitride used in the second method contains dispersed particles, a compound serving as a sintering aid, and an organic compound which forms free carbon by heating. All of these powders need to be excellent in sinterability and moldability, and preferably have an average particle size of 2 μm or less and an oxygen content of 2.0% by weight or less. However, when an excessively fine AlN powder is used, the sinterability is high but the formability (sheet molding, extrusion molding,
Press molding, etc.) and have an appropriate particle size. The amount of oxygen can be contained in a wide amount range because the degree of the effect of deoxidation by carbon described later can be controlled by varying the amount of carbon contained in the powder. I don't like the oxygen I get. Similarly, it is not preferable that the solid solution contains carbon in the particles or unreacted Al ₂ O ₃ or the like exists in the powder.

In the second method, starting materials that are precursors of aluminum nitride (for example, aluminum compounds such as Al and Al ₂ O ₃ )
In addition, previously added powder of dispersed particles or a precursor thereof, a powder to be a sintering aid or a precursor thereof, and a powder of carbon or an organic substance that forms free carbon by heating,
The synthetic powder is obtained through various procedures for synthesizing the aluminum nitride powder. The powder that becomes the dispersed particles, the powder that becomes the sintering aid, and the organic substance that forms free carbon by heating may be further added to the synthesized powder, if necessary.

For example, if preparation of the synthetic powder is nitrided reduction method of Al ₂ O _3, organic substances are carbon or a precursor thereof in Al ₂ O ₃ powder, a precursor of the fine the dispersed particles elements and / or compounds thereof, baked After the precursor of the compound serving as a binder is added and mixed in advance, the mixture is heated in a nitrogen-containing atmosphere at a temperature of 1400 ° C. or higher to obtain the same synthetic powder. Furthermore, regardless of the method of synthesizing AlN, for example, a direct nitridation method of Al other than the reduced nitrogen method of Al ₂ O ₃ or a gas phase reaction method using a raw material containing an Al component,
By appropriately adding components other than AlN, a synthetic powder of the second production method of the present invention can be obtained.

The starting material used as the dispersed particles and the sintering aid includes oxides, hydroxides, carbonates, and oxalates containing these target elements, or solutions of alkoxides and the like dissolved in alcohol. There may be. Preferably, it is finely mixed and dispersed in AlN powder with a fine powder having a mean particle size of 0.2 μm or less or a solution.

In the first method, powders of these metals or oxides, carbides, and nitrides are added to the AlN powder, and in the second method, they are added in advance and included in the AlN powder synthesis.
The added amount of these components to be dispersed particles is the amount required to be present in the sintered body finally in the range of 0.01 to 30% by weight, preferably 0.01 to 5.0% by weight in terms of their elements. I do.

The amount of the alkaline earth or rare earth compound to be added as a sintering aid is finally 0.01% in terms of those elements in the sintered body.
The amount is required to be present in the range of -10% by weight, preferably in the range of 0.01-3.0% by weight.

The amount of carbon added simultaneously or the amount of organic substance that forms free carbon by heating may be, for example, 1000 during heating.
The amount of free carbon generated by heating at a temperature of not more than ℃ is in the range of 0.01 to 5.0% by weight. As a carbon source, for example, carbon such as acetylene black or graphite, or phenol resin or PVB used as a molding aid (binder) is decomposed to the above temperature by heating to generate free carbon. . This free carbon is AlN
Remove oxygen present on the surface or inside of the powder (O
Is removed as CO gas. For example, Al ₂ O ₃ is reduced and C
It releases O gas or evaporates as a lower oxide) and reduces finely dispersed elements and their compounds. For example, the added TiO ₂ powder is reduced by this carbon and then immediately nitrided by nitrogen in the atmosphere.
It becomes TiN and is taken up and dispersed in the AlN particles.

The molding and sintering of the mixed powder and the synthetic powder are performed by a known method. The sintering is performed at 1600 to 2000 ° C. in a nitrogen-containing non-oxidizing atmosphere.

Hereinafter, an example will be described. In the following examples,
This is an example of a manufacturing method and the like, and the present invention is not limited thereto.

The measuring method of each characteristic in this specification is as follows.

-The particle size was observed by SEM or TEM in principle, and the average particle size by the sedimentation method was used for the particle size of the powder.

Elemental analysis was quantitative analysis after melting of metal element or alkali, and carbon and oxygen were confirmed by gas analysis (using a gas analyzer manufactured by Leco).

-The bending strength is as described above.

-The light absorption coefficient was measured after the both surfaces of the sample were mirror-finished with a spectrophotometer to obtain a 0.5 mm thick specimen.

-Thermal conductivity was measured by two-dimensional measurement by a laser flash method (using a device equivalent to TC-7000 manufactured by Vacuum Riko).

The porosity is calculated based on the theoretical density of aluminum nitride as 3.26 g / cm ³
Was calculated from the measured density.

-The measured density was measured by the Archimedes method.

The lattice constant and the half width were confirmed by X-ray diffraction using Si as a standard.

Example 1 AlN powder (average particle size 0.8 μm, oxygen content 1.5% by weight, A
In addition to the amount of metal impurities excluding l and 0.1% by weight of carbon, and the content of carbon of 0.03% by weight), a dispersion compound powder having an average particle diameter of 0.5 μm or less shown in Table 1 and a Y ₂ O ₃ powder ( Average particle size 0.
5 μm, purity 99.9%) 0.5% by weight, phenol resin 1.0% by weight, PVB 10% by weight, and a slurry obtained by mixing in a toluene-based solvent for 10 hours with a nylon ball and a nylon pot, and forming a sheet. After drying in a cast, a sheet having a thickness of 0.8 mm was obtained. This sheet was punched into a 50 mm square to form a square sheet, which was then placed in a BN crucible and heated at 1850 ° C. for 5 hours in nitrogen to obtain a sintered body. 1000 during heating
When the sample was taken out at a temperature of ° C. and analyzed for the amount of carbon, the free carbon was 0.6% by weight. Table 1 shows the properties of the obtained sintered body.

Example 2 AlN powder (average particle size 0.8 μm, oxygen content 1.5% by weight, A
0.1% by weight or less of metallic impurities except l, carbon content of 0.03% by weight), TiO ₂ powder (average particle size 0.1μm, purity 99.9%)
Was added in an amount shown in Table 2 as a sintering aid, and 1.0% by weight of phenol resin and PMM were added.
A (polymethyl methacrylate) is added by 10% by weight,
The mixture was mixed in a naphtha-based solvent using a nylon pot and a nylon ball for 10 hours. The resulting slurry was cast into a sheet and dried to obtain a 0.8 mm thick sheet. This sheet was punched into a 50 mm square to form a square sheet, which was heated at 1850 ° C. in nitrogen for 3 hours in a BN crucible to obtain a sintered body. Table 2 shows the characteristics of the sintered body.

Example 3 AlN powder (average particle size: 1.0 μm, oxygen content: 1.2% by weight, A
l and 0.1% by weight of metal impurities excluding l and a carbon content of 0.05% by weight) to the additives shown in Table 3 and Y ₂ O ₃ as a sintering aid.
1.0% by weight, and 0.8% by weight of phenol resin
Then, 10% by weight of PMMA (polymethyl methacrylate) was added as a molding binder, and mixed in a naphtha-based solvent using a nylon pot and nylon balls for 10 hours. The obtained slurry was cast into a sheet and then dried to obtain a sheet having a thickness of 0.8 mm. This sheet was punched into a 50 mm square to form a square sheet, which was then placed in nitrogen at 1850 ° C.
The sintered body was obtained by heating in a BN crucible for 3 hours. Table 3 shows the characteristics of the sintered body.

Example 4 AlN powder (average particle size 1.2 μm, oxygen content 1.0% by weight, A
TiO ₂ powder (average particle size: 0.2 μm, purity: 99.9%)
And 0.5% by weight of Y ₂ O ₃ powder as a sintering aid, and various weight percentages of graphite and phenolic resin shown in Table 4 as a free carbon source, and PMMA (PMMA) as a molding binder. 10% by weight of polymethyl methacrylate) and mixed in a naphtha-based solvent for 10 hours using a nylon pot and a nylon ball. The resulting slurry was cast into a sheet and dried to obtain a 0.8 mm thick sheet. This sheet was punched into a 50 mm square to form a square sheet, which was heated at 1800 ° C. in nitrogen for 5 hours in a BN crucible to obtain a sintered body. Table 4 shows the characteristics of the sintered body.

Example 5 An AlN powder containing 0.5% by weight of TiO ₂ powder (average particle size: 0.1 μm, purity: 99.9%) was synthesized by a direct nitridation method, a reduction nitridation method, and an alkylaluminum decomposition method (the characteristics are shown in Table 5).
This AlN powder is mixed with Y ₂ O ₃ powder (average particle size 0.5 μm, purity 99.9
0.5% by weight), 1.0% by weight of a phenol resin as a free carbon source, and 10% by weight of PVB as a molding binder, and using a nylon pot and a nylon ball in a toluene-based solvent. And mixed for 5 hours. The obtained slurry was cast into a sheet and dried to obtain a sheet having a thickness of 0.7 mm. This sheet was punched into a 50 mm square to form a square sheet, which was heated at 1850 ° C. in nitrogen in an AlN crucible for 3 hours to obtain a sintered body.
Table 5 shows the characteristics of the sintered body.

Example 6 AlN powders containing various additives were synthesized by a direct nitriding method, a reduction nitriding method, and an alkylaluminum decomposition method (the characteristics are shown in Table 6). Y ₂ O ₃ powder to the AlN powder (average particle size 0.5μ
m, purity 99.9%), 0.5% by weight of phenol resin as a free carbon source, and 10% by weight of PVB as a molding binder. And mixed for 5 hours. The obtained slurry was cast into a sheet and dried to obtain a sheet having a thickness of 0.7 mm. 50mm for this sheet
The sheet was punched into a square to form a rectangular sheet, which was heated at 1850 ° C. in nitrogen in a crucible made of AlN for 3 hours to obtain a sintered body.
Table 6 shows the characteristics of the sintered body.

Example 7 AlN powder (average particle size 0.8 μm, oxygen content 1.0% by weight, A
l to 0.1% by weight of metal impurities excluding l and 0.03% by weight of carbon), various Ti compound powders shown in Table 7 were added, 1.0% by weight of a phenol resin as a free carbon source, and PMMA as a molding binder. Was added in a naphtha-based solvent for 10 hours using a nylon pot and a nylon ball. The resulting slurry was cast into a sheet and dried to obtain a 0.8 mm thick sheet. 5 this sheet
Punched into 0 mm square to form a square sheet, which was placed in nitrogen
And sintering. Table 7 shows the characteristics of the sintered body.

Example 8 AlN powder (average particle size 0.8 μm, oxygen content 1.0% by weight, A
1.0% by weight of TiO ₂ powder with an average particle diameter of 0.1 μm to the metal impurities (excluding metal impurities of 0.1% by weight or less, carbon content of 0.03% by weight), and 1.0% by weight of a phenol resin as a free carbon source. 10% by weight of PMMA, and use a nylon pot and nylon ball in a naphtha-based solvent.
Mix for hours. The obtained slurry was cast into a sheet and dried, and then punched into a 50 mm square to obtain a square sheet having a thickness of 0.8 mm. The sheet was sintered at 1850 ° C. for 5 hours in a nitrogen stream. The lattice constant of the obtained sintered body is 3.111 a-axis.
{, C-axis 4.981}, c / a was 1.601, the same as that produced under the same conditions without adding TiO ₂ . The thermal conductivity is
It was 170 W / m · K and 190 W / m · K. The half value is 2θ
At 0.10 deg, which was larger than 0.05 deg when TiO ₂ was not added.

[Brief description of the drawings]

FIG. 1 is a TEM photograph (magnification: 10,000 times) of an aluminum nitride sintered body according to the present invention, in which TiN particles are dispersed in AlN crystals, and Al ₂ O ₃ and Y ₂ O ₃ phases are present at crystal grain boundaries. Indicates that it exists.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kohei Shimoda 1-1-1 Kunyokita, Itami-shi, Itami-shi, Hyogo Sumitomo Electric Industries, Ltd. Itami Works (56) References JP-A 1-298071 (JP, A (58) Field surveyed (Int.Cl. ⁶ , DB name) C04B 35/58

Claims (9)

(57) [Claims] An aluminum nitride particle having a hexagonal wurtzite structure and having an average particle diameter of 1 μm or more, and compound particles having a non-wurtzite structure having an average particle diameter of 1/5 or less of that of aluminum nitride particles. Characterized by being finely dispersed without being dissolved in an aluminum nitride crystal lattice. 2. The aluminum nitride sintered body according to claim 1, wherein the finely dispersed particles are compounds having a NaCl structure. 3. The finely dispersed particles are Ti, Zr, Hf, V, Nb,
A compound of at least one element selected from the group consisting of Ta, Mo, W, Fe, Co, and Ni in an amount of 0.01 to 30% by weight in terms of element;
The aluminum nitride sintered body according to claim 1, wherein the aluminum nitride sintered body includes: 4. The method according to claim 1, wherein a grain boundary phase composed of a compound phase of a sintering aid and Al ₂ O ₃ contains the fine particle compound. The aluminum nitride sintered body according to the item. 5. The aluminum nitride sintered body according to claim ¹ , wherein an absorption coefficient of light having a wavelength of 500 nm is 50 cm ⁻¹ or more. 6. Ti, Zr, Hf, V, Nb, Ta, Mo, and Ti having an average particle diameter of 1 μm or less are dispersed in aluminum nitride powder.
W, Fe, Co, a compound powder of at least one element selected from the group consisting of Ni, an organic compound that forms free carbon by heating, and a free carbon amount of 0.01 to 5.
A step of mixing and mixing powder in an amount within a range of 0% by weight, a step of molding the mixed powder to form a molded body, and a step of molding the molded body in a nitrogen-containing non-oxidizing atmosphere at 1600 to 2000 And sintering at ℃. 7. The production of an aluminum nitride sintered body according to claim 6, wherein in the step of forming the mixed powder, a compound serving as a sintering aid is further added and mixed. Method. 8. An aluminum nitride precursor, which is synthesized from a raw material which is aluminum nitride, and Ti, Zr, Hf, V, Nb, Ta, Mo, W, Fe, and Ti having an average particle diameter of 1 μm or less as dispersed particles.
A compound of at least one element selected from the group consisting of Co and Ni, and an organic compound capable of forming free carbon in an amount capable of forming 0.01 to 5.0% by weight of free carbon in a subsequent heating step. A step of preparing an aluminum nitride synthetic powder containing, a step of molding the synthetic powder into a molded body, and a step of sintering the molded body at 1600 to 2000 ° C. in a non-oxidizing atmosphere containing nitrogen. A method for producing an aluminum nitride sintered body, comprising: 9. The aluminum nitride sinter according to claim 8, wherein the step of preparing the aluminum nitride synthetic powder further comprises a compound serving as a sintering aid. How to make the body.