WO2022210520A1 - Aluminum nitride sintered body, method for producing same, circuit board, and multilayer substrate - Google Patents

Aluminum nitride sintered body, method for producing same, circuit board, and multilayer substrate Download PDF

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WO2022210520A1
WO2022210520A1 PCT/JP2022/014944 JP2022014944W WO2022210520A1 WO 2022210520 A1 WO2022210520 A1 WO 2022210520A1 JP 2022014944 W JP2022014944 W JP 2022014944W WO 2022210520 A1 WO2022210520 A1 WO 2022210520A1
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aluminum nitride
sintered body
nitride sintered
particles
sintering aid
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PCT/JP2022/014944
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French (fr)
Japanese (ja)
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江 尹
和久 森
勝博 小宮
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デンカ株式会社
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
    • C04B35/58—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides
    • C04B35/581—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on borides, nitrides, i.e. nitrides, oxynitrides, carbonitrides or oxycarbonitrides or silicides based on aluminium nitride
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/12—Mountings, e.g. non-detachable insulating substrates
    • H01L23/13—Mountings, e.g. non-detachable insulating substrates characterised by the shape
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/12—Mountings, e.g. non-detachable insulating substrates
    • H01L23/14—Mountings, e.g. non-detachable insulating substrates characterised by the material or its electrical properties
    • H01L23/15—Ceramic or glass substrates
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/03—Use of materials for the substrate

Definitions

  • the present disclosure relates to an aluminum nitride sintered body, a method for manufacturing the same, a circuit board, and a laminated substrate.
  • a circuit board or the like having a ceramic plate is used in such a power module in order to efficiently diffuse heat generated from a semiconductor element and to suppress leakage current.
  • a ceramic sintered body used for such a ceramic plate is generally manufactured by forming a ceramic raw material powder into a predetermined shape to form a ceramic green body, and then sintering the ceramic green body.
  • Patent Document 1 discloses that a nitride selected from the group of Zr and Ti is used in an amount of 3 to 20 parts by mass in terms of oxide as a sintering aid, and an aluminum nitride sintered body is used. Techniques for increasing the thermal conductivity and mechanical strength of steel have been proposed.
  • Electronic components such as power modules are expected to have even higher performance, and along with this, it is believed that the level of demand for the performance of various products used in electronic components will continue to rise. Along with this, it is expected that the amount of heat generated during use of electronic parts will increase, and excellent bending strength to withstand the influence of the difference in thermal expansion coefficient between the constituent members of electronic parts, that is, the difference in the amount of deformation between the constituent members. is required.
  • An object of the present disclosure is to provide an aluminum nitride sintered body with excellent bending strength and a method for producing the same.
  • An object of the present disclosure is to provide a laminated substrate and a circuit substrate which include the aluminum nitride sintered body and have excellent connection reliability.
  • One aspect of the present disclosure includes aluminum nitride particles and sintering aid particles, the average particle diameter of the aluminum nitride particles is 2.0 to 10.0 ⁇ m, and the surface in a cross section horizontal to the thickness direction
  • the value of BA is 6.0 area% or less.
  • the average particle diameter of the sintering aid particles in the surface layer is C ⁇ m and the average particle diameter of the sintering aid particles in the intermediate layer is D ⁇ m
  • DC is 4.0 ⁇ m or less.
  • the aluminum nitride sintered body contains aluminum nitride particles having a predetermined average particle size, and the total amount and particle size distribution of the sintering aid particles satisfy the above-described conditions, so that the structure is excellent in uniformity. , stress concentration is suppressed when force is applied, and excellent bending strength can be exhibited.
  • the total amount of the sintering aid particles on the main surface may be less than 4.0 area %.
  • the aluminum nitride sintered body has a particle diameter when the integrated value from the small particle diameter reaches 90% of the total in the cumulative frequency distribution curve of the particle diameter measured by electron microscope image analysis for the aluminum nitride particles.
  • d90 may be 13.0 ⁇ m or less.
  • the above d90 and the average particle size may be 1.0 to 3.5 ⁇ m.
  • One aspect of the present disclosure provides a circuit board comprising the aluminum nitride sintered body described above and a conductor portion attached to the aluminum nitride sintered body.
  • the circuit board has the above-described aluminum nitride sintered body, even when the temperature during use is high, the circuit board can withstand deformation between members and exhibit excellent connection reliability.
  • One aspect of the present disclosure provides a laminated substrate comprising the aluminum nitride sintered body described above and a metal plate attached to the aluminum nitride sintered body.
  • the laminated substrate has the above-described aluminum nitride sintered body, even when the temperature during use is high, it can withstand deformation between members and can exhibit excellent connection reliability.
  • One aspect of the present disclosure has a firing step of obtaining a sintered body by firing a molded body composed of a mixture containing aluminum nitride and a sintering aid, and the sintering aid includes yttrium oxide and aluminum oxide. and the mass ratio of the aluminum oxide to the yttrium oxide is less than 0.5, and the firing step is a step of obtaining a first fired body from the molded body by heating at 1500 to 1700 ° C. for 1 hour or more and a step of obtaining the sintered body from the first fired body by heating at more than 1700 ° C. and 1850 ° C. or less for 1 hour or more, and the firing time of the firing step is 14.0 hours or less.
  • a method for manufacturing an aluminum nitride sintered body is provided.
  • the method for producing the aluminum nitride sintered body uses a sintering aid blended in a predetermined ratio, and sintering in at least two stages of predetermined firing processes.
  • Aluminum sintered bodies can be produced.
  • an aluminum nitride sintered body with excellent bending strength and a method for producing the same can be provided. According to the present disclosure, it is also possible to provide a laminated substrate and a circuit substrate that are equipped with the aluminum nitride sintered body and have excellent connection reliability.
  • FIG. 1 is a perspective view showing an example of an aluminum nitride sintered body.
  • FIG. 2 is a perspective view showing an example of a laminated substrate.
  • FIG. 3 is a perspective view showing an example of a circuit board.
  • the materials exemplified in this specification can be used singly or in combination of two or more unless otherwise specified.
  • the content of each component in the composition means the total amount of the multiple substances present in the composition unless otherwise specified when there are multiple substances corresponding to each component in the composition.
  • the sintering aid particles are particles containing a component derived from the sintering aid.
  • FIG. 1 is a perspective view showing an example of an aluminum nitride sintered body.
  • the shape of the ceramic plate 100 made of an aluminum nitride sintered body may be, for example, a sheet shape, and is usually a rectangular parallelepiped shape.
  • the average particle size of the aluminum nitride particles is 2.0 to 10.0 ⁇ m.
  • the upper limit of the average particle size of the aluminum nitride particles is, for example, 9.5 ⁇ m or less, 9.0 ⁇ m or less, 8.0 ⁇ m or less, 7.0 ⁇ m or less, 6.0 ⁇ m or less, 5.0 ⁇ m or less, or 4.5 ⁇ m or less. It can be.
  • the upper limit of the average particle diameter is within the above range, it is possible to suppress the extension of defects in the particles due to grain growth, and to further suppress the decrease in bending strength.
  • the lower limit of the average particle size of the aluminum nitride particles may be, for example, 2.5 ⁇ m or more, 3.0 ⁇ m or more, or 3.5 ⁇ m or more.
  • an aluminum nitride sintered body having excellent flexural strength and excellent thermal properties (thermal conductivity) can be obtained.
  • the average particle size of aluminum nitride particles in this specification means a value measured by the following method. First, a scanning electron microscope image (observed at a magnification of 2000) of a cross section horizontal to the thickness direction of the aluminum nitride sintered body is obtained. The measurement target is a position half the thickness of the aluminum nitride sintered body. A region of 50 ⁇ m ⁇ 50 ⁇ m is determined at an arbitrary position in the acquired image, and the particle size distribution of the aluminum nitride particles is created using image analysis software. A particle size is determined at which the cumulative frequency from the small particle size side in the cumulative frequency distribution curve of particle sizes measured by electron microscope image analysis obtained as described above is 50%.
  • the particle diameters are determined for five regions in the same manner as described above, and the arithmetic average value is taken as the average particle diameter of aluminum nitride.
  • the shape of the aluminum nitride particles is usually not constant. Therefore, the particle diameter of aluminum nitride particles is defined as the distance between the two most distant points on the circumference of the particle to be measured.
  • image analysis software for example, "GIMP2" (trade name) or "imageJ" (trade name) distributed under the GNU GPL can be used.
  • the aluminum nitride sintered body has a particle diameter when the integrated value from the small particle diameter reaches 90% of the total in the cumulative frequency distribution curve of the particle diameter measured by electron microscope image analysis for the aluminum nitride particles.
  • d90 is, for example, 13.0 ⁇ m or less, 12.0 ⁇ m or less, 11.0 ⁇ m or less, 10.0 ⁇ m or less, 9.0 ⁇ m or less, 8.0 ⁇ m or less, 7.0 ⁇ m or less, 6.0 ⁇ m or less , or 5.5 ⁇ m or less.
  • the fact that the upper limit of d90 is within the above range means that the formation of coarse particles in the aluminum nitride sintered body is suppressed and that the structure of the sintered body is more uniform. That is, it is possible to suppress the occurrence of stress concentration when a force is applied from the outside, and to further improve the bending strength of the sintered body.
  • the lower limit of d90 may be, for example, 4.0 ⁇ m or more, or 4.5 ⁇ m or more. When the lower limit of d90 is within the above range, it is possible to exhibit excellent bending strength and suppress deterioration of other properties such as thermal conductivity.
  • d90 When the lower limit of d90 is within the above range, it is possible to facilitate the production of the aluminum nitride sintered body and to suppress an increase in cost.
  • d90 may be adjusted within the ranges described above, and may be, for example, 4.0-13.0 ⁇ m, or 4.0-6.0 ⁇ m.
  • the difference between the d90 and the average particle size of the aluminum nitride particles may be, for example, 1.0 to 3.5 ⁇ m.
  • the difference between the d90 and the average particle size may be, for example, 3.0 ⁇ m or less, 2.8 ⁇ m or less, 2.6 ⁇ m or less, 2.4 ⁇ m or less, or 2.2 ⁇ m or less.
  • the upper limit of the difference is within the above range, the structure of the aluminum nitride sintered body can be made finer, and the size of defects can be made smaller.
  • the difference between the d90 and the average particle size may be, for example, 1.1 ⁇ m or more, or 1.2 ⁇ m or more.
  • the lower limit of the difference is within the above range, it is possible to more easily manufacture the aluminum nitride sintered body and to suppress an increase in cost.
  • the total amount of the sintering aid particles in the surface layer is A area%
  • the total amount of the sintering aid particles in the intermediate layer is B area%.
  • BA is 6.0 area % or less.
  • the upper limit of the BA value may be, for example, 5.5 area % or less, 5.0 area % or less, 4.5 area % or less, or 4.0 area % or less.
  • the existence form and distribution of the sintering aid particles can be made more uniform, thereby further improving the bending strength.
  • the lower limit of the BA value is not particularly limited, but may be, for example, 0.1 area % or more, or 0.2 area % or more.
  • the value of BA may be adjusted within the ranges described above, and may be, for example, 0.1 to 6.0 area %, or 0.1 to 5.5 area %.
  • DC is 4.0 ⁇ m or less.
  • the upper limit of the DC value may be, for example, 3.5 ⁇ m or less, 3.0 ⁇ m or less, or 2.5 ⁇ m or less.
  • the fact that the upper limit of DC is within the above range means that the variation in the sintering aid particles in the thickness direction of the aluminum nitride sintered body is suppressed, and the sintered body structure is more uniform.
  • the lower limit of the DC value is not particularly limited, but may be, for example, 0.1 ⁇ m or more.
  • the value of DC may be adjusted within the ranges described above, for example, 0.1 to 4.0 ⁇ m, or 0.1 to 3.5 ⁇ m.
  • the total amount of sintering aid particles in this specification means the value measured by the following method.
  • the measurement targets are a region (surface layer) from the surface layer of the aluminum nitride sintered body to 50 ⁇ m and a region (intermediate layer) from half the thickness to 100 ⁇ m above and below.
  • a region of 50 ⁇ m ⁇ 50 ⁇ m is determined at an arbitrary position in each of the acquired images of the surface layer and intermediate layer, binarized (threshold: 140) using image analysis software, and the total area of the sintering aid particles is calculated.
  • the total area of the sintering aid particles is determined for the five regions in the same manner as described above, and the arithmetic average value is taken as the total amount of the sintering aid particles.
  • image analysis software for example, "GIMP2" (trade name) or "imageJ” (trade name) distributed under the GNU GPL can be used.
  • the average particle size of the sintering aid particles in this specification is the equivalent circle diameter of the sintering aid particles in the image obtained by binarizing the scanning electron microscope image obtained as described above. and the value obtained by arithmetic mean of the obtained equivalent circle diameters.
  • Sintering aid particles can also be observed on the main surface of the aluminum nitride sintered body. It can be said that the sintering aid particles observed on the main surface are residues of the sintering aid that try to escape from the main surface to the outside of the system during the production process of the aluminum nitride sintered body. If the observed amount of sintering aid particles on the main surface is large, the sintering aid will be insufficient inside the aluminum nitride sintered body, and the internal structure will tend to be non-uniform.
  • the total amount of the sintering aid particles on the main surface is, for example, less than 4.0 area%, 3.8 area% or less, 3.6 area% or less, or 3.4 area% or less. , 3.2 area % or less, or 3.0 area % or less.
  • the upper limit of the total amount of the sintering aid particles on the main surface is within the above range, the resulting aluminum nitride sintered body can have a more dense structure.
  • the lower limit of the total amount of the sintering aid particles on the main surface is not particularly limited, but is, for example, 0.1 area% or more, 0.2 area% or more, or 0.5 area%. good.
  • the total amount of the sintering aid particles on the main surface may be adjusted within the above range, for example, 0.1 area % or more and less than 4.0 area %, 0.1 to 3.8 area %, or 0.1 area % or more and less than 4.0 area %. It may be from 1 to 3.6 area %.
  • the total amount of the sintering aid particles on the main surface means a value measured by the following method.
  • image analysis software for example, "GIMP2" (trade name) or "imageJ" (trade name) distributed under the GNU GPL can be used.
  • the aluminum nitride sintered body is composed of aluminum nitride particles and sintering aid particles as described above, but other components other than the aluminum nitride particles and sintering aid particles are added to the extent that the effects of the present invention are not impaired. may be included in Other components may be, for example, additives for imparting desired effects, impurities, and the like.
  • the content of other components is, for example, 10.0% by mass or less, 5.0% by mass or less, 3.0% by mass or less, or 1.0% by mass or less, based on the total amount of the aluminum nitride sintered body, or It may be 0.5% by mass or less.
  • the aluminum nitride sintered body has excellent bending strength.
  • the bending strength of the aluminum nitride sintered body can be, for example, 360 MPa or more, 370 MPa or more, 390 MPa or more, 400 MPa or more, 450 MPa or more, or 500 MPa or more.
  • Bending strength in this specification means a value measured according to the method described in JIS C 2141:1992 "Electrical insulating ceramic material test method". Specifically, it is measured according to the method described in the Examples of this specification.
  • the aluminum nitride sintered body has a uniform structure, the distribution of bending strength is sufficiently suppressed.
  • the aluminum nitride sintered body has a relatively large Weibull coefficient in the Weibull statistical analysis of its bending strength.
  • the Weibull coefficient for the bending strength of the aluminum nitride sintered body is, for example, 10.0 or more, 12.0 or more. It can be 13.0 or more, 14.0 or more, 15.0 or more, or 16.0 or more.
  • the aluminum nitride sintered body described above can be produced, for example, by the following method.
  • One embodiment of the method for producing an aluminum nitride sintered body has a firing step of firing a molded body composed of a mixture containing aluminum nitride and a sintering aid to obtain a sintered body.
  • Additives include binders, plasticizers, dispersion media, release agents, and the like. Binders include, for example, methylcellulose-based binders having plasticity or surfactant effects, and acrylic acid ester-based binders having excellent thermal decomposability. Examples of plasticizers include glycerin and the like. Dispersion media include, for example, ion-exchanged water and ethanol.
  • Aluminum nitride is not particularly limited, and aluminum nitride powder produced by a known method such as a direct nitriding method in which metal aluminum is nitrided in a nitrogen atmosphere, and a reduction nitriding method in which aluminum oxide is reduced with carbon. Available.
  • the sintering aid contains yttrium oxide and aluminum oxide.
  • the sintering aid may be particulate.
  • the mass ratio of aluminum oxide to yttrium oxide (content of aluminum oxide/content of yttrium oxide) is less than 0.5. Thereby, aggregation of oxides in the aluminum nitride sintered body can be suppressed.
  • the mixing ratio of yttrium oxide and aluminum oxide can be adjusted within the range described above, thereby adjusting the oxide composition in the aluminum nitride sintered body.
  • Aluminum oxide and yttrium oxide form a liquid phase of a composite oxide during sintering to promote sintering. Thereby, the aluminum nitride sintered body can be sufficiently densified.
  • the content of the sintering aid may be, for example, 1 to 10.0 parts by mass with respect to 100 parts by mass of aluminum nitride.
  • the content of the sintering aid is a value calculated from the amount of the sintering aid in terms of oxide.
  • the content of aluminum oxide may be, for example, 0.1 to 5.0 parts by mass with respect to 100 parts by mass of aluminum nitride.
  • the content of aluminum oxide may be, for example, 0.1 to 5.0 parts by mass with respect to 100 parts by mass of aluminum nitride.
  • the aluminum nitride, the sintering aid, and the additive added as necessary may be blended and mixed and used as a forming raw material.
  • the forming raw material is formed, for example, into a sheet by a known method such as a doctor blade method.
  • the molded body obtained may be degreased.
  • the degreasing method is not particularly limited, and for example, the compact may be heated to 300 to 700° C. in air or in a non-oxidizing atmosphere such as nitrogen.
  • the heating time may be, for example, 1 to 10 hours.
  • the aluminum nitride sintered body can be obtained by firing the above compact.
  • the baking step (hereinafter also referred to as the baking step) may be performed in an inert gas atmosphere.
  • the inert gas may be, for example, nitrogen or the like.
  • the firing step may be performed under atmospheric pressure.
  • the firing step includes a step of obtaining a first fired body from the molded body by heating at 1500 to 1700 ° C. for 1 hour or more (hereinafter also referred to as a first firing step), and a step of heating at more than 1700 ° C. and 1850 ° C. or less for 1 hour. and a step of obtaining the sintered body from the first sintered body by heating as described above (hereinafter also referred to as a second sintering step).
  • the firing temperature in the first firing step can be selected depending on the composition of the sintering aid, and may be, for example, 1650°C or higher, or 1680°C or higher.
  • the rate of temperature increase until the firing temperature in the first firing step is reached may be relatively high, for example, 20° C./min or more, or 30° C./min or more.
  • the sintering temperature is preferably maintained for a predetermined period of time.
  • the firing time in the first firing step may be, for example, 1.0 hours or longer, 2.0 hours or longer, or 2.5 hours or longer.
  • the firing temperature in the second firing step is, for example, less than 1850°C, less than 1840°C, or 1830°C or less from the viewpoint of improving the texture density of the obtained sintered body and suppressing the removal of the auxiliary agent from the surface layer. you can
  • the rate of temperature increase until reaching the firing temperature in the second firing step may be, for example, 0.5° C./min or more, or 1.0° C./min or more.
  • the sintering temperature is preferably maintained for a predetermined period of time.
  • the firing time in the second firing step may be, for example, 1.0 hours or longer, 1.5 hours or longer, or 2.0 hours or longer.
  • firing time refers to the time during which the temperature of the atmosphere in which the object to be fired, such as the molded article, is placed reaches the firing temperature and is maintained at that temperature.
  • the total firing time of the first firing step and the second firing step in the firing step is 14.0 hours or less, but for example, 10.0 hours or less, 8.0 hours or less, or 7.0 hours or less. can be By setting the total firing time within the above range, it is possible to reduce the leakage of the sintering aid from the surface layer of the molded body or aluminum nitride sintered body to the surface of the molded body or aluminum nitride sintered body. , the surface roughness can be reduced.
  • the total firing time of the first firing step and the second firing step in the firing step may be, for example, 4.5 hours or longer, or 5.0 hours or longer.
  • the sintering aid can be melted, the aluminum nitride particles can be sufficiently dissolved, and the aluminum nitride particles can grow in a more uniform environment.
  • An aluminum nitride sintered body with a more uniform grain size distribution and a more dense structure can be prepared.
  • the firing time of the firing step can be adjusted within the range described above, and may be, for example, 5.0 to 8.0 hours.
  • the aluminum nitride sintered body obtained by the above manufacturing method may be processed into a desired shape as necessary.
  • the aluminum nitride sintered body may be processed into, for example, a plate shape to form an aluminum nitride plate.
  • a substrate may be formed by attaching a metal part such as a metal circuit or a metal plate to an aluminum nitride plate.
  • the substrate may be, for example, a laminated substrate in which the main surface of an aluminum nitride plate and the main surface of a metal plate such as a copper plate are bonded together.
  • it may be a circuit board having a circuit pattern formed by removing a part of a metal plate by etching or the like to form a conductor portion.
  • the substrate of the present disclosure may be a laminate substrate or a circuit substrate.
  • the lower limit of the thickness of the aluminum nitride sintered body may be, for example, 0.10 mm or more, 0.20 mm or more, or 0.25 mm or more.
  • the upper limit of the thickness of the aluminum nitride sintered body may be, for example, 3.00 mm or less, 1.50 mm or less, or 1.00 mm or less.
  • the thickness of the aluminum nitride sintered body can be adjusted within the above range, and may be, for example, 0.10-3.00 mm, or 0.25-1.00 mm.
  • FIG. 2 is a perspective view showing an example of a laminated substrate.
  • the laminated substrate 200 includes a pair of metal plates 110 arranged to face each other, and a ceramic plate 100 made of an aluminum nitride sintered body between the pair of metal plates 110 .
  • Examples of the metal plate 110 include a copper plate.
  • the shape and size of the ceramic plate 100 and the metal plate 110 may be the same or different.
  • the metal plate 110 and the ceramic plate 100 may be joined by, for example, brazing material.
  • One of the pair of metal plates 110 may be used as a heat dissipation material, and the other may be processed into a circuit pattern.
  • the circuit pattern may be formed by etching the metal plate 110 using a resist. As a result, it is possible to form a circuit board capable of sufficiently suppressing leakage current or the like, or to form a heat dissipation board.
  • FIG. 3 is a perspective view showing an example of a circuit board.
  • the circuit board 300 includes a ceramic plate 100 , a plurality of conductor portions 20 and a metal plate 110 .
  • the conductor portion 20 is provided on one surface 100A of the ceramic plate 100
  • the metal plate 110 is provided on the other surface of the ceramic plate 100.
  • the metal plate 110 may function as a heat dissipation material.
  • the ceramic plate 100 in the laminated board 200 and the circuit board 300 is composed of an aluminum nitride sintered body with excellent electrical insulation and thermal conductivity. Therefore, it has excellent reliability when used in various products such as power modules.
  • the present disclosure is not limited to the above embodiments.
  • the shape and structure of the substrates of the present disclosure are not limited to those of FIGS.
  • circuit patterns may be formed on both main surfaces of the ceramic plate 100 .
  • the conductor portion 20 may be formed by spraying metal powder and heat-treating it. Also, the descriptions of the above-described embodiments can be applied to each other.
  • Example 1 Preparation of Aluminum Nitride Sintered Body
  • 6.0 parts by mass of yttrium oxide powder and 0.3 parts by mass of ⁇ -aluminum oxide are blended as sintering aids and mixed using a ball mill to obtain a mixed powder. Obtained.
  • cellulose ether binder manufactured by Shin-Etsu Chemical Co., Ltd., trade name: Metrose
  • glycerin manufactured by Kao Corporation, trade name: Excepar
  • ion exchange 10 parts by mass of water was added and mixed for 1 minute using a Henschel mixer to obtain a molding raw material.
  • This molding raw material is molded with a screw type extruder to produce a sheet-like molded body (width: 80 mm, thickness: 0.8 mm), dried at 100 ° C. for 1 hour, and then cut into a length of 60 mm.
  • x Width: 60 mm shaped compact was obtained.
  • boron nitride powder as a release agent was applied to this compact, a plurality of the laminates were laminated and the mass of the laminate was adjusted to 95 kg.
  • the resulting laminate was degreased by heating in air at 570° C. for 10 hours to obtain a degreased body.
  • the degreased body was placed in a heating furnace and heated from 25° C. to 1700 at a rate of 20° C./min under atmospheric pressure in a nitrogen gas atmosphere, and held at 1700 for 2.0 hours (first firing step).
  • the temperature was raised to 1830° C. at a rate of temperature rise of 5° C./min and held at 1830° C. for 8 hours (second firing step).
  • the heating was stopped and the aluminum nitride sintered body was obtained by standing to cool in the heating furnace.
  • Example 2 The heating rate in the first firing step was changed to 30°C/min and the firing time was changed to 1.0 hour, and the firing temperature in the second firing step was changed to 1800°C and the firing time was changed to 1 hour.
  • An aluminum nitride sintered body was prepared in the same manner as in Example 1 except for the above.
  • Example 3 In the same manner as in Example 1, except that the firing time in the first firing step was changed to 8.0 hours, and the firing temperature in the second firing step was changed to 1850 ° C. and the firing time was changed to 4 hours. , an aluminum nitride sintered body was prepared.
  • Example 4 An aluminum nitride sintered body was prepared in the same manner as in Example 1, except that the firing temperature was changed to 1820° C. and the firing time was changed to 4 hours in the second firing step.
  • Example 5 In the first firing step, the firing temperature was changed to 1500 ° C. and the firing time was changed to 3 hours, and in the second firing step, the firing temperature was changed to 1800 ° C. and the firing time was changed to 4 hours.
  • An aluminum nitride sintered body was prepared in the same manner as in 1.
  • Example 6 An aluminum nitride sintered body was prepared in the same manner as in Example 1, except that in the second firing step, the heating rate was changed to 1°C/min, the firing temperature was changed to 1840°C, and the firing time was changed to 2 hours. .
  • Example 7 An aluminum nitride sintered body was prepared in the same manner as in Example 1, except that in the second firing step, the heating rate was changed to 1°C/min, the firing temperature was changed to 1830°C, and the firing time was changed to 2 hours. .
  • Example 1 The heating rate was changed to 30°C/min and the firing temperature to 1450°C in the first firing step, and the heating rate was changed to 0.3°C/min and the firing temperature to 1900°C in the second firing step.
  • a sintered body of aluminum nitride was obtained in the same manner as in Example 1, except that the firing time was changed to 2 hours.
  • Comparative example 2 An aluminum nitride sintered body was prepared in the same manner as in Comparative Example 1, except that in the second firing step, the heating rate was changed to 5°C/min, the firing temperature was changed to 1870°C, and the firing time was changed to 10 hours. .
  • an aluminum nitride sintered body with excellent bending strength and a method for producing the same can be provided. According to the present disclosure, it is also possible to provide a laminated substrate and a circuit substrate that are equipped with the aluminum nitride sintered body and have excellent connection reliability.

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Abstract

One aspect of the present disclosure provides an aluminum nitride sintered body which contains aluminum nitride particles and sintering assistant particles, wherein: the aluminum nitride particles have an average particle diameter of 2.0 μm to 10.0 μm; if A (% by area) is the total area of the sintering assistant particles in a surface layer and B (% by area) is the total area of the sintering assistant particles in an intermediate layer in a cross-section that is parallel to the thickness direction, the value of (B - A) is 6.0% by area; and if C (μm) is the average particle diameter of the sintering assistant particles in the surface layer and D (μm) is the average particle diameter of the sintering assistant particles in the intermediate layer, (D - C) is 4.0 μm or less.

Description

窒化アルミニウム焼結体、及びその製造方法、回路基板、並びに、積層基板Aluminum nitride sintered body, manufacturing method thereof, circuit board, and laminated board
　本開示は、窒化アルミニウム焼結体、及びその製造方法、回路基板、並びに、積層基板に関する。 The present disclosure relates to an aluminum nitride sintered body, a method for manufacturing the same, a circuit board, and a laminated substrate.
　近年、モーター等の産業機器、及び電気自動車等の製品には、大電力制御用のパワーモジュールが用いられている。このようなパワーモジュールには、半導体素子から発生する熱を効率的に拡散するとともに、漏れ電流を抑制するため、セラミック板を備える回路基板等が用いられている。このようなセラミック板に用いられるセラミック焼結体は、通常、セラミック原料粉末を所定形状に成形してセラミック成形体とした後に、セラミック成形体を焼結することで製造される。 In recent years, industrial equipment such as motors and products such as electric vehicles use power modules for high power control. A circuit board or the like having a ceramic plate is used in such a power module in order to efficiently diffuse heat generated from a semiconductor element and to suppress leakage current. A ceramic sintered body used for such a ceramic plate is generally manufactured by forming a ceramic raw material powder into a predetermined shape to form a ceramic green body, and then sintering the ceramic green body.
　セラミック焼結体としては、窒化物、炭化物、硼化物、又は珪化物等で構成されるものが知られている。このうち、窒化アルミニウム焼結体は、熱伝導性及び電気絶縁性に優れている。このため、パワーモジュール等の電子部品のヒートシンク材として用いられている。これらの用途への適性を高めるため、特許文献１では、焼結助剤として酸化物換算で３～２０質量部のＺｒ，Ｔｉの群から選択される窒化物を用いて、窒化アルミニウム焼結体の熱伝導率と機械的強度を高くする技術が提案されている。 As ceramic sintered bodies, those composed of nitrides, carbides, borides, silicides, etc. are known. Among them, the aluminum nitride sintered body is excellent in thermal conductivity and electrical insulation. Therefore, it is used as a heat sink material for electronic parts such as power modules. In order to improve suitability for these uses, Patent Document 1 discloses that a nitride selected from the group of Zr and Ti is used in an amount of 3 to 20 parts by mass in terms of oxide as a sintering aid, and an aluminum nitride sintered body is used. Techniques for increasing the thermal conductivity and mechanical strength of steel have been proposed.
特開２０１８－１８４３１６号公報JP 2018-184316 A
　パワーモジュール等の電子部品は、一層の高性能化が図られており、これに伴って、電子部品に用いられる各種製品の性能への要求レベルが益々高くなっていくと考えられる。これに伴い、電子部品の使用時における発熱量の上昇が想定され、電子部品の構成部材間の熱膨張率の差による影響、すなわち構成部材間の変形量の違いに耐えるための優れた曲げ強さが求められる。 Electronic components such as power modules are expected to have even higher performance, and along with this, it is believed that the level of demand for the performance of various products used in electronic components will continue to rise. Along with this, it is expected that the amount of heat generated during use of electronic parts will increase, and excellent bending strength to withstand the influence of the difference in thermal expansion coefficient between the constituent members of electronic parts, that is, the difference in the amount of deformation between the constituent members. is required.
　本開示の目的は、曲げ強さに優れる窒化アルミニウム焼結体及びその製造方法を提供することである。本開示の目的は、上記窒化アルミニウム焼結体を備え、接続信頼性に優れる積層基板及び回路基板を提供することである。 An object of the present disclosure is to provide an aluminum nitride sintered body with excellent bending strength and a method for producing the same. An object of the present disclosure is to provide a laminated substrate and a circuit substrate which include the aluminum nitride sintered body and have excellent connection reliability.
　本開示の一側面は、窒化アルミニウム粒子と、焼結助剤粒子と、を含み、上記窒化アルミニウム粒子の平均粒子径が２．０～１０．０μｍであり、厚み方向に水平な断面における、表面層の上記焼結助剤粒子の総量をＡ面積％とし、中間層の上記焼結助剤粒子の総量をＢ面積％としたときの、Ｂ－Ａの値が６．０面積％以下であり、表面層の上記焼結助剤粒子の平均粒子径をＣμｍとし、中間層の上記焼結助剤粒子の平均粒子径をＤμｍとしたときの、Ｄ－Ｃが４．０μｍ以下である、窒化アルミニウム焼結体を提供する。 One aspect of the present disclosure includes aluminum nitride particles and sintering aid particles, the average particle diameter of the aluminum nitride particles is 2.0 to 10.0 μm, and the surface in a cross section horizontal to the thickness direction When the total amount of the sintering aid particles in the layer is A area% and the total amount of the sintering aid particles in the intermediate layer is B area%, the value of BA is 6.0 area% or less. , where the average particle diameter of the sintering aid particles in the surface layer is C μm and the average particle diameter of the sintering aid particles in the intermediate layer is D μm, DC is 4.0 μm or less. A sintered aluminum body is provided.
　上記窒化アルミニウム焼結体は、所定の平均粒子径の窒化アルミニウム粒子を含み、焼結助剤粒子に関する総量及び粒子径の分布が上述の条件を満たすものであることから、組織の均一性に優れ、力が加わった際の応力集中が抑制されており、優れた曲げ強さを発揮し得る。 The aluminum nitride sintered body contains aluminum nitride particles having a predetermined average particle size, and the total amount and particle size distribution of the sintering aid particles satisfy the above-described conditions, so that the structure is excellent in uniformity. , stress concentration is suppressed when force is applied, and excellent bending strength can be exhibited.
　上記窒化アルミニウム焼結体は、主面における上記焼結助剤粒子の総量が４．０面積％未満であってよい。 In the aluminum nitride sintered body, the total amount of the sintering aid particles on the main surface may be less than 4.0 area %.
　上記窒化アルミニウム焼結体は、上記窒化アルミニウム粒子に対する電子顕微鏡画像解析によって測定される粒子径の累積頻度分布曲線において、小粒径からの積算値が全体の９０％に達した時の粒子径をｄ９０としたときに、ｄ９０が１３．０μｍ以下であってよい。 The aluminum nitride sintered body has a particle diameter when the integrated value from the small particle diameter reaches 90% of the total in the cumulative frequency distribution curve of the particle diameter measured by electron microscope image analysis for the aluminum nitride particles. d90 may be 13.0 μm or less.
　上記窒化アルミニウム粒子に対する電子顕微鏡画像解析によって測定される粒子径の累積頻度分布曲線において、小粒径からの積算値が全体の９０％に達した時の粒子径をｄ９０としたときに、上記ｄ９０と上記平均粒子径との差が１．０～３．５μｍであってよい。 In the cumulative frequency distribution curve of particle diameters measured by electron microscope image analysis for the aluminum nitride particles, when the particle diameter when the integrated value from the small particle diameter reaches 90% of the total is d90, the above d90 and the average particle size may be 1.0 to 3.5 μm.
　本開示の一側面は、上述の窒化アルミニウム焼結体と、当該窒化アルミニウム焼結体に取り付けられている導体部と、を備える、回路基板を提供する。 One aspect of the present disclosure provides a circuit board comprising the aluminum nitride sintered body described above and a conductor portion attached to the aluminum nitride sintered body.
　上記回路基板は、上述の窒化アルミニウム焼結体を有することから、使用時の温度が高い場合であっても、部材間の変形に耐えることができ、優れた接続信頼性を発揮し得る。 Since the circuit board has the above-described aluminum nitride sintered body, even when the temperature during use is high, the circuit board can withstand deformation between members and exhibit excellent connection reliability.
　本開示の一側面は、上述の窒化アルミニウム焼結体と、当該窒化アルミニウム焼結体に取り付けられている金属板と、を備える、積層基板を提供する。 One aspect of the present disclosure provides a laminated substrate comprising the aluminum nitride sintered body described above and a metal plate attached to the aluminum nitride sintered body.
　上記積層基板は、上述の窒化アルミニウム焼結体を有することから、使用時の温度が高い場合であっても、部材間の変形に耐えることができ、優れた接続信頼性を発揮し得る。 Since the laminated substrate has the above-described aluminum nitride sintered body, even when the temperature during use is high, it can withstand deformation between members and can exhibit excellent connection reliability.
　本開示の一側面は、窒化アルミニウム及び焼結助剤を含む混合物で構成される成形体を焼成して焼結体を得る焼成工程を有し、上記焼結助剤は酸化イットリウム及び酸化アルミニウムを含有し、上記酸化イットリウムに対する上記酸化アルミニウムの質量比が０．５未満であり、上記焼成工程は、１５００～１７００℃で１時間以上加熱することによって、上記成形体から第一焼成体を得る工程と、１７００℃超１８５０℃以下で１時間以上加熱することによって、上記第一焼成体から上記焼結体を得る工程と、を含み、上記焼成工程の焼成時間は１４．０時間以下である、窒化アルミニウム焼結体の製造方法を提供する。 One aspect of the present disclosure has a firing step of obtaining a sintered body by firing a molded body composed of a mixture containing aluminum nitride and a sintering aid, and the sintering aid includes yttrium oxide and aluminum oxide. and the mass ratio of the aluminum oxide to the yttrium oxide is less than 0.5, and the firing step is a step of obtaining a first fired body from the molded body by heating at 1500 to 1700 ° C. for 1 hour or more and a step of obtaining the sintered body from the first fired body by heating at more than 1700 ° C. and 1850 ° C. or less for 1 hour or more, and the firing time of the firing step is 14.0 hours or less. A method for manufacturing an aluminum nitride sintered body is provided.
　上記窒化アルミニウム焼結体の製造方法は、所定の割合で配合された焼結助剤を使用し、少なくとも２段階の所定の焼成工程によって焼成することによって、上述のような曲げ強さに優れる窒化アルミニウム焼結体を製造できる。 The method for producing the aluminum nitride sintered body uses a sintering aid blended in a predetermined ratio, and sintering in at least two stages of predetermined firing processes. Aluminum sintered bodies can be produced.
　本開示によれば、曲げ強さに優れる窒化アルミニウム焼結体及びその製造方法を提供できる。本開示によればまた、上記窒化アルミニウム焼結体を備え、接続信頼性に優れる積層基板及び回路基板を提供できる。 According to the present disclosure, an aluminum nitride sintered body with excellent bending strength and a method for producing the same can be provided. According to the present disclosure, it is also possible to provide a laminated substrate and a circuit substrate that are equipped with the aluminum nitride sintered body and have excellent connection reliability.
図１は、窒化アルミニウム焼結体の一例を示す斜視図である。FIG. 1 is a perspective view showing an example of an aluminum nitride sintered body. 図２は、積層基板の一例を示す斜視図である。FIG. 2 is a perspective view showing an example of a laminated substrate. 図３は、回路基板の一例を示す斜視図である。FIG. 3 is a perspective view showing an example of a circuit board.
　以下、場合によって図面を参照して、本開示の実施形態を説明する。ただし、以下の実施形態は、本開示を説明するための例示であり、本開示を以下の内容に限定する趣旨ではない。説明において、同一要素又は同一機能を有する要素には同一符号を用い、場合によって重複する説明は省略する。また、上下左右等の位置関係は、特に断らない限り、図面に示す位置関係に基づくものとする。更に、各要素の寸法比率は図示の比率に限られるものではない。 Hereinafter, embodiments of the present disclosure will be described with reference to the drawings as the case may be. However, the following embodiments are examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following contents. In the description, the same reference numerals are used for the same elements or elements having the same functions, and duplicate descriptions are omitted depending on the case. In addition, unless otherwise specified, positional relationships such as up, down, left, and right are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratio of each element is not limited to the illustrated ratio.
　本明細書において例示する材料は特に断らない限り、１種を単独で又は２種以上を組み合わせて用いることができる。組成物中の各成分の含有量は、組成物中の各成分に該当する物質が複数存在する場合には、特に断らない限り、組成物中に存在する当該複数の物質の合計量を意味する。上記焼結助剤粒子とは、焼結助剤に由来する成分を含む粒子である。 The materials exemplified in this specification can be used singly or in combination of two or more unless otherwise specified. The content of each component in the composition means the total amount of the multiple substances present in the composition unless otherwise specified when there are multiple substances corresponding to each component in the composition. . The sintering aid particles are particles containing a component derived from the sintering aid.
　窒化アルミニウム焼結体の一実施形態は、窒化アルミニウム粒子と、焼結助剤粒子と、を含む。図１は、窒化アルミ焼結体の一例を示す斜視図である。窒化アルミニウム焼結体で構成されるセラミック板１００の形状は、例えば、シート状であってよく、通常、直方体形状である。 An embodiment of the aluminum nitride sintered body includes aluminum nitride particles and sintering aid particles. FIG. 1 is a perspective view showing an example of an aluminum nitride sintered body. The shape of the ceramic plate 100 made of an aluminum nitride sintered body may be, for example, a sheet shape, and is usually a rectangular parallelepiped shape.
　上記窒化アルミニウム粒子の平均粒子径が２．０～１０．０μｍである。窒化アルミニウム粒子の平均粒子径の上限値は、例えば、９．５μｍ以下、９．０μｍ以下、８．０μｍ以下、７．０μｍ以下、６．０μｍ以下、５．０μｍ以下、又は４．５μｍ以下であってよい。上記平均粒子径の上限値が上記範囲内であることで、粒成長に伴う粒子内の欠陥の伸展を抑え、曲げ強さの低下をより抑制することができる。窒化アルミニウム粒子の平均粒径の下限値は、例えば、２．５μｍ以上、３．０μｍ以上、又は３．５μｍ以上であってよい。上記平均粒子径の下限値が上記範囲内であることで、優れた曲げ強さに加えて熱特性（熱伝導性）にも優れる窒化アルミニウム焼結体とすることができる。 The average particle size of the aluminum nitride particles is 2.0 to 10.0 μm. The upper limit of the average particle size of the aluminum nitride particles is, for example, 9.5 μm or less, 9.0 μm or less, 8.0 μm or less, 7.0 μm or less, 6.0 μm or less, 5.0 μm or less, or 4.5 μm or less. It can be. When the upper limit of the average particle diameter is within the above range, it is possible to suppress the extension of defects in the particles due to grain growth, and to further suppress the decrease in bending strength. The lower limit of the average particle size of the aluminum nitride particles may be, for example, 2.5 μm or more, 3.0 μm or more, or 3.5 μm or more. When the lower limit of the average particle size is within the above range, an aluminum nitride sintered body having excellent flexural strength and excellent thermal properties (thermal conductivity) can be obtained.
　本明細書における窒化アルミニウム粒子の平均粒子径とは、以下の方法で測定される値を意味する。まず、窒化アルミニウム焼結体の厚み方向に水平な断面の走査型電子顕微鏡画像（２０００倍で観察）を取得する。測定対象は窒化アルミニウム焼結体の厚みの半分の位置とする。取得した画像における任意の位置において、５０μｍ×５０μｍの領域を決定し、画像解析ソフトを用いて、窒化アルミニウム粒子の粒度分布を作成する。上述のようにして得られた、電子顕微鏡画像解析によって測定される粒子径の累積頻度分布曲線における小粒子径側からの累積頻度が５０％となる粒子径を決定する。同画像において、上述と同様にして、５個の領域について粒子径を決定し、その算術平均値を窒化アルミニウムの平均粒子径とする。なお、窒化アルミニウム粒子の形状は通常一定でない。そこで、窒化アルミニウム粒子の粒径は、測定対象となる粒子の外周の最も離れた二点の距離とする。画像解析ソフトは、例えば、ＧＮＵ　ＧＰＬの下で配布されている「ＧＩＭＰ２」（商品名）又は「ｉｍａｇｅＪ」（商品名）等を使用できる。 The average particle size of aluminum nitride particles in this specification means a value measured by the following method. First, a scanning electron microscope image (observed at a magnification of 2000) of a cross section horizontal to the thickness direction of the aluminum nitride sintered body is obtained. The measurement target is a position half the thickness of the aluminum nitride sintered body. A region of 50 μm×50 μm is determined at an arbitrary position in the acquired image, and the particle size distribution of the aluminum nitride particles is created using image analysis software. A particle size is determined at which the cumulative frequency from the small particle size side in the cumulative frequency distribution curve of particle sizes measured by electron microscope image analysis obtained as described above is 50%. In the same image, the particle diameters are determined for five regions in the same manner as described above, and the arithmetic average value is taken as the average particle diameter of aluminum nitride. Incidentally, the shape of the aluminum nitride particles is usually not constant. Therefore, the particle diameter of aluminum nitride particles is defined as the distance between the two most distant points on the circumference of the particle to be measured. For image analysis software, for example, "GIMP2" (trade name) or "imageJ" (trade name) distributed under the GNU GPL can be used.
　上記窒化アルミニウム焼結体は、上記窒化アルミニウム粒子に対する電子顕微鏡画像解析によって測定される粒子径の累積頻度分布曲線において、小粒径からの積算値が全体の９０％に達した時の粒子径をｄ９０としたときに、ｄ９０は、例えば、１３．０μｍ以下、１２．０μｍ以下、１１．０μｍ以下、１０．０μｍ以下、９．０μｍ以下、８．０μｍ以下、７．０μｍ以下、６．０μｍ以下、又は５．５μｍ以下であってよい。ｄ９０の上限値が上記範囲内であることは、窒化アルミニウム焼結体中に粗大粒子の生成が抑制されていることを意味し、焼結体組織がより一層均一であることを意味する。すなわち、外部から力が加えられた際の応力集中が生じることを抑制し、焼結体の曲げ強さをより向上することができる。ｄ９０の下限値は、例えば、４．０μｍ以上、又は４．５μｍ以上であってよい。ｄ９０の下限値が上記範囲内であることで、優れた曲げ強さを発揮すると共に、熱伝導率などの他の特性の低下を抑制することができる。ｄ９０の下限値が上記範囲内であることでまた、窒化アルミニウム焼結体の製造をより容易にすると共に、コストの上昇を抑制することができる。ｄ９０は上述の範囲内で調整してよく、例えば、４．０～１３．０μｍ、又は４．０～６．０μｍであってよい。 The aluminum nitride sintered body has a particle diameter when the integrated value from the small particle diameter reaches 90% of the total in the cumulative frequency distribution curve of the particle diameter measured by electron microscope image analysis for the aluminum nitride particles. When d90, d90 is, for example, 13.0 μm or less, 12.0 μm or less, 11.0 μm or less, 10.0 μm or less, 9.0 μm or less, 8.0 μm or less, 7.0 μm or less, 6.0 μm or less , or 5.5 μm or less. The fact that the upper limit of d90 is within the above range means that the formation of coarse particles in the aluminum nitride sintered body is suppressed and that the structure of the sintered body is more uniform. That is, it is possible to suppress the occurrence of stress concentration when a force is applied from the outside, and to further improve the bending strength of the sintered body. The lower limit of d90 may be, for example, 4.0 μm or more, or 4.5 μm or more. When the lower limit of d90 is within the above range, it is possible to exhibit excellent bending strength and suppress deterioration of other properties such as thermal conductivity. When the lower limit of d90 is within the above range, it is possible to facilitate the production of the aluminum nitride sintered body and to suppress an increase in cost. d90 may be adjusted within the ranges described above, and may be, for example, 4.0-13.0 μm, or 4.0-6.0 μm.
　上記窒化アルミニウム粒子は上記ｄ９０と上記平均粒子径との差が、例えば、１．０～３．５μｍであってよい。上記ｄ９０と上記平均粒子径との差は、例えば、３．０μｍ以下、２．８μｍ以下、２．６μｍ以下、２．４μｍ以下、又は２．２μｍ以下であってよい。上記差の上限値が上記範囲内であることで、窒化アルミニウム焼結体の組織をより微細化することができ、欠陥等の大きさをより小さなものとすることができる。上記ｄ９０と上記平均粒子径との差は、例えば、１．１μｍ以上、又は１．２μｍ以上であってよい。上記差の下限値が上記範囲内であることで、窒化アルミニウム焼結体の製造をより容易にすると共に、コストの上昇を抑制することができる。 The difference between the d90 and the average particle size of the aluminum nitride particles may be, for example, 1.0 to 3.5 μm. The difference between the d90 and the average particle size may be, for example, 3.0 μm or less, 2.8 μm or less, 2.6 μm or less, 2.4 μm or less, or 2.2 μm or less. When the upper limit of the difference is within the above range, the structure of the aluminum nitride sintered body can be made finer, and the size of defects can be made smaller. The difference between the d90 and the average particle size may be, for example, 1.1 μm or more, or 1.2 μm or more. When the lower limit of the difference is within the above range, it is possible to more easily manufacture the aluminum nitride sintered body and to suppress an increase in cost.
　窒化アルミニウム焼結体の厚み方向に水平な断面における、表面層の上記焼結助剤粒子の総量をＡ面積％とし、中間層の上記焼結助剤粒子の総量をＢ面積％としたときの、Ｂ－Ａの値は６．０面積％以下である。Ｂ－Ａの値の上限値は、例えば、５．５面積％以下、５．０面積％以下、４．５面積％以下、又は４．０面積％以下であってよい。Ｂ－Ａの値の上限値が上記範囲内であることで、焼結助剤粒子の存在形態及び分布をより一層均一化させることができ、これによって曲げ強さを更に向上させることができる。Ｂ－Ａの値の下限値は、特に限定されるものではないが、例えば、０．１面積％以上、又は０．２面積％以上であってよい。Ｂ－Ａの値は上述の範囲内で調整してよく、例えば、０．１～６．０面積％、又は０．１～５．５面積％であってよい。 In the cross section horizontal to the thickness direction of the aluminum nitride sintered body, the total amount of the sintering aid particles in the surface layer is A area%, and the total amount of the sintering aid particles in the intermediate layer is B area%. , BA is 6.0 area % or less. The upper limit of the BA value may be, for example, 5.5 area % or less, 5.0 area % or less, 4.5 area % or less, or 4.0 area % or less. When the upper limit of the value of BA is within the above range, the existence form and distribution of the sintering aid particles can be made more uniform, thereby further improving the bending strength. The lower limit of the BA value is not particularly limited, but may be, for example, 0.1 area % or more, or 0.2 area % or more. The value of BA may be adjusted within the ranges described above, and may be, for example, 0.1 to 6.0 area %, or 0.1 to 5.5 area %.
　窒化アルミニウム焼結体の厚み方向に水平な断面における、表面層の上記焼結助剤粒子の平均粒子径をＣμｍとし、中間層の上記焼結助剤粒子の平均粒子径をＤμｍとしたときの、Ｄ－Ｃは４．０μｍ以下である。Ｄ－Ｃの値の上限値は、例えば、３．５μｍ以下、３．０μｍ以下、又は２．５μｍ以下であってよい。Ｄ－Ｃの上限値が上記範囲内であることは、窒化アルミニウム焼結体における厚み方向での焼結助剤粒子のバラつきが抑制されていることを意味し、焼結体組織がより一層均一であることを意味する。すなわち、外部から力が加えられた際の応力集中が生じることを抑制し、焼結体の曲げ強さをより向上することができる。Ｄ－Ｃの値の下限値は、特に限定されるものではないが、例えば、０．１μｍ以上であってよい。Ｄ－Ｃの値は上述の範囲内で調整してよく、例えば、０．１～４．０μｍ、又は０．１～３．５μｍであってよい。 When the average particle diameter of the sintering aid particles in the surface layer is C μm and the average particle diameter of the sintering aid particles in the intermediate layer is D μm in the cross section parallel to the thickness direction of the aluminum nitride sintered body , DC is 4.0 μm or less. The upper limit of the DC value may be, for example, 3.5 μm or less, 3.0 μm or less, or 2.5 μm or less. The fact that the upper limit of DC is within the above range means that the variation in the sintering aid particles in the thickness direction of the aluminum nitride sintered body is suppressed, and the sintered body structure is more uniform. means that That is, it is possible to suppress the occurrence of stress concentration when a force is applied from the outside, and to further improve the bending strength of the sintered body. The lower limit of the DC value is not particularly limited, but may be, for example, 0.1 μm or more. The value of DC may be adjusted within the ranges described above, for example, 0.1 to 4.0 μm, or 0.1 to 3.5 μm.
　本明細書における焼結助剤粒子の総量は、以下の方法で測定される値を意味する。まず、窒化アルミニウム焼結体の厚み方向に水平な断面の走査型電子顕微鏡画像（２０００倍で観察）を取得する。測定対象は窒化アルミニウム焼結体の表層から５０μｍまでの領域（表面層）と、厚みの半分の位置から上下１００μｍまでの領域（中間層）とする。取得した表面層及び中間層の画像それぞれにおける任意の位置において、５０μｍ×５０μｍの領域を決定し、画像解析ソフトを用いて二値化（閾値：１４０）し、焼結助剤粒子の総面積を測定する。同画像において、上述と同様にして、５個の領域について焼結助剤粒子の総面積を決定し、その算術平均値を焼結助剤粒子の総量とする。画像解析ソフトは、例えば、ＧＮＵ　ＧＰＬの下で配布されている「ＧＩＭＰ２」（商品名）又は「ｉｍａｇｅＪ」（商品名）等を使用できる。また、本明細書における焼結助剤粒子の平均粒子径は、上述のように取得された走査型電子顕微鏡画像を二値化して得た画像において、焼結助剤粒子の円相当径を測定し、得られた円相当径の算術平均によって得られた値を意味する。 The total amount of sintering aid particles in this specification means the value measured by the following method. First, a scanning electron microscope image (observed at a magnification of 2000) of a cross section horizontal to the thickness direction of the aluminum nitride sintered body is obtained. The measurement targets are a region (surface layer) from the surface layer of the aluminum nitride sintered body to 50 μm and a region (intermediate layer) from half the thickness to 100 μm above and below. A region of 50 μm × 50 μm is determined at an arbitrary position in each of the acquired images of the surface layer and intermediate layer, binarized (threshold: 140) using image analysis software, and the total area of the sintering aid particles is calculated. Measure. In the same image, the total area of the sintering aid particles is determined for the five regions in the same manner as described above, and the arithmetic average value is taken as the total amount of the sintering aid particles. For image analysis software, for example, "GIMP2" (trade name) or "imageJ" (trade name) distributed under the GNU GPL can be used. In addition, the average particle size of the sintering aid particles in this specification is the equivalent circle diameter of the sintering aid particles in the image obtained by binarizing the scanning electron microscope image obtained as described above. and the value obtained by arithmetic mean of the obtained equivalent circle diameters.
　窒化アルミニウム焼結体の主面においても焼結助剤粒子が観察し得る。主面において観察される焼結助剤粒子は、窒化アルミニウム焼結体の製造過程で主面から系外に抜け出ようとする焼結助剤の残留ともいえる。主面における焼結助剤粒子の観測量が多いと、窒化アルミニウム焼結体の内部において焼結助剤が不足し、内部の組織が不均一となる傾向にある。また、焼結助剤の抜け出し量が増大し、窒化アルミニウム焼結体の主面に留まらずに、系外に除去された場合、当該主面は助剤粒子の抜けた凹部が形成されることになり表面平滑度に影響する。また、焼結助剤の抜けた凹部が観察される場合、窒化アルミニウム焼結体の厚み方向に水平な断面における表面層における窒化アルミニウム粒子の成長が不足する傾向にある。このため、窒化アルミニウム焼結体の組織が不均一になり得る。 Sintering aid particles can also be observed on the main surface of the aluminum nitride sintered body. It can be said that the sintering aid particles observed on the main surface are residues of the sintering aid that try to escape from the main surface to the outside of the system during the production process of the aluminum nitride sintered body. If the observed amount of sintering aid particles on the main surface is large, the sintering aid will be insufficient inside the aluminum nitride sintered body, and the internal structure will tend to be non-uniform. In addition, when the amount of the sintering aid that escapes increases and is removed outside the system without remaining on the main surface of the aluminum nitride sintered body, a recessed portion from which the aid particles have escaped is formed on the main surface. and affects the surface smoothness. Further, when recessed portions where the sintering aid is removed are observed, there is a tendency that the growth of the aluminum nitride particles in the surface layer in the cross section horizontal to the thickness direction of the aluminum nitride sintered body is insufficient. For this reason, the structure of the aluminum nitride sintered body may become non-uniform.
　上記窒化アルミニウム焼結体は、主面における上記焼結助剤粒子の総量が、例えば、４．０面積％未満、３．８面積％以下、３．６面積％以下、３．４面積％以下、３．２面積％以下、又は３．０面積％以下であってよい。主面における上記焼結助剤粒子の総量の上限値が上記範囲内であることで、得られる窒化アルミニウム焼結体の組織がより一層緻密なものとなり得る。主面における上記焼結助剤粒子の総量の下限値は、特に限定されるものではないが、例えば、０．１面積％以上、０．２面積％以上、又は０．５面積％であってよい。主面における上記焼結助剤粒子の総量は上述の範囲内で調整してよく、例えば、０．１面積％以上４．０面積％未満、０．１～３．８面積％、又は０．１～３．６面積％であってよい。 In the aluminum nitride sintered body, the total amount of the sintering aid particles on the main surface is, for example, less than 4.0 area%, 3.8 area% or less, 3.6 area% or less, or 3.4 area% or less. , 3.2 area % or less, or 3.0 area % or less. When the upper limit of the total amount of the sintering aid particles on the main surface is within the above range, the resulting aluminum nitride sintered body can have a more dense structure. The lower limit of the total amount of the sintering aid particles on the main surface is not particularly limited, but is, for example, 0.1 area% or more, 0.2 area% or more, or 0.5 area%. good. The total amount of the sintering aid particles on the main surface may be adjusted within the above range, for example, 0.1 area % or more and less than 4.0 area %, 0.1 to 3.8 area %, or 0.1 area % or more and less than 4.0 area %. It may be from 1 to 3.6 area %.
　上記主面における上記焼結助剤粒子の総量は、以下の方法で測定される値を意味する。まず、窒化アルミニウム焼結体の主面の走査型電子顕微鏡画像（１０００倍で観察）を取得する。取得した画像における任意の位置において１．２ｍｍ×１．２ｍｍの領域を決定し、画像解析ソフトを用いて二値化（閾値：１４０）し、焼結助剤粒子の総面積を測定する。同画像において、上述と同様にして、５個の領域について焼結助剤粒子の総面積を決定し、その算術平均値を焼結助剤粒子の総量とする。画像解析ソフトは、例えば、ＧＮＵ　ＧＰＬの下で配布されている「ＧＩＭＰ２」（商品名）又は「ｉｍａｇｅＪ」（商品名）等を使用できる。 The total amount of the sintering aid particles on the main surface means a value measured by the following method. First, a scanning electron microscope image (observed at a magnification of 1000) of the main surface of the aluminum nitride sintered body is acquired. A region of 1.2 mm×1.2 mm is determined at an arbitrary position in the obtained image, binarized (threshold value: 140) using image analysis software, and the total area of the sintering aid particles is measured. In the same image, the total area of the sintering aid particles is determined for the five regions in the same manner as described above, and the arithmetic average value is taken as the total amount of the sintering aid particles. For image analysis software, for example, "GIMP2" (trade name) or "imageJ" (trade name) distributed under the GNU GPL can be used.
　上記窒化アルミニウム焼結体は、上述のとおり窒化アルミニウム粒子と焼結助剤粒子とから構成されるが、窒化アルミニウム粒子及び焼結助剤粒子以外のその他の成分を本発明の効果を害さない範囲で含んでもよい。その他の成分は、例えば、所望の効果を付与するための添加剤、及び不純物等であってよい。その他の成分の含有量は、窒化アルミニウム焼結体の全量を基準として、例えば、１０．０質量％以下、５．０質量％以下、３．０質量％以下、１．０質量％以下、又は０．５質量％以下であってよい。 The aluminum nitride sintered body is composed of aluminum nitride particles and sintering aid particles as described above, but other components other than the aluminum nitride particles and sintering aid particles are added to the extent that the effects of the present invention are not impaired. may be included in Other components may be, for example, additives for imparting desired effects, impurities, and the like. The content of other components is, for example, 10.0% by mass or less, 5.0% by mass or less, 3.0% by mass or less, or 1.0% by mass or less, based on the total amount of the aluminum nitride sintered body, or It may be 0.5% by mass or less.
　上記窒化アルミニウム焼結体は曲げ強さに優れる。上記窒化アルミニウム焼結体の曲げ強さは、例えば、３６０ＭＰａ以上、３７０ＭＰａ以上、３９０ＭＰａ以上、４００ＭＰａ以上、４５０ＭＰａ以上、又は５００ＭＰａ以上とすることができる。本明細書における曲げ強さは、ＪＩＳ　Ｃ　２１４１：１９９２「電気絶縁用セラミック材料試験方法」に記載の方法に準拠して測定される値を意味する。具体的には、本明細書の実施例に記載の方法に沿って測定する。 The aluminum nitride sintered body has excellent bending strength. The bending strength of the aluminum nitride sintered body can be, for example, 360 MPa or more, 370 MPa or more, 390 MPa or more, 400 MPa or more, 450 MPa or more, or 500 MPa or more. Bending strength in this specification means a value measured according to the method described in JIS C 2141:1992 "Electrical insulating ceramic material test method". Specifically, it is measured according to the method described in the Examples of this specification.
　上記窒化アルミニウム焼結体は組織が均一であることから、上述の曲げ強さの分布も十分抑制されている。上記窒化アルミニウム焼結体は、その曲げ強さに対するワイブル統計による解析において、ワイブル係数が比較的大きなものとなっている。上記窒化アルミニウム焼結体の曲げ強さに対する上記ワイブル係数は、例えば、１０．０以上、１２．０以上。１３．０以上、１４．０以上、１５．０以上、又は１６．０以上とすることもできる。 Since the aluminum nitride sintered body has a uniform structure, the distribution of bending strength is sufficiently suppressed. The aluminum nitride sintered body has a relatively large Weibull coefficient in the Weibull statistical analysis of its bending strength. The Weibull coefficient for the bending strength of the aluminum nitride sintered body is, for example, 10.0 or more, 12.0 or more. It can be 13.0 or more, 14.0 or more, 15.0 or more, or 16.0 or more.
　ワイブル統計は、曲げ強さの分布を評価するために用いられる。窒化アルミニウム焼結体について、縦軸に破壊確率Ｆ（σ）、横軸に曲げ強さσ（破壊時強度、抗折強度）を取ったワイブルプロットを作成した場合の、傾きｍがワイブル係数である。ワイブルプロットにおける破壊確率Ｆ（σ）は、下記式（１）で与えられる。
　Ｆ（σ）＝１－ｅｘｐ［－（σ／η）ｍ］・・・（１）
　上記式（１）中、ηはフィッティングパラメータである。 Weibull statistics are used to evaluate the distribution of flexural strength. For the aluminum nitride sintered body, when a Weibull plot is created with the vertical axis of the fracture probability F (σ) and the horizontal axis of the bending strength σ (strength at break, bending strength), the slope m is the Weibull coefficient. be. The failure probability F(σ) in the Weibull plot is given by the following formula (1).
F(σ)=1−exp[−(σ/η) m ] (1)
In the above formula (1), η is a fitting parameter.
　上述の窒化アルミニウム焼結体は、例えば、以下のような方法で製造することができる。窒化アルミニウム焼結体の製造方法の一実施形態は、窒化アルミニウム及び焼結助剤を含む混合物で構成される成形体を焼成して焼結体を得る焼成工程を有する。 The aluminum nitride sintered body described above can be produced, for example, by the following method. One embodiment of the method for producing an aluminum nitride sintered body has a firing step of firing a molded body composed of a mixture containing aluminum nitride and a sintering aid to obtain a sintered body.
　まず、原料を準備する。原料としては、例えば、窒化アルミニウム、焼結助剤、及び、必要に応じて添加剤を用いる。添加剤としては、バインダー、可塑剤、分散媒、及び離型剤等が挙げられる。バインダーとしては、例えば、可塑性又は界面活性効果を有するメチルセルロース系のもの、熱分解性に優れたアクリル酸エステル系のものが挙げられる。可塑剤としては、例えば、グリセリン等が挙げられる。分散媒としては、例えば、イオン交換水及びエタノール等が挙げられる。 "First, prepare the ingredients." As raw materials, for example, aluminum nitride, sintering aids, and, if necessary, additives are used. Additives include binders, plasticizers, dispersion media, release agents, and the like. Binders include, for example, methylcellulose-based binders having plasticity or surfactant effects, and acrylic acid ester-based binders having excellent thermal decomposability. Examples of plasticizers include glycerin and the like. Dispersion media include, for example, ion-exchanged water and ethanol.
　窒化アルミニウムは、特に限定されるものではなく、金属アルミニウムを窒素雰囲気下で窒化する直接窒化法、及び、酸化アルミニウムをカーボンで還元する還元窒化法等、公知の方法で製造された窒化アルミニウム粉末を使用できる。 Aluminum nitride is not particularly limited, and aluminum nitride powder produced by a known method such as a direct nitriding method in which metal aluminum is nitrided in a nitrogen atmosphere, and a reduction nitriding method in which aluminum oxide is reduced with carbon. Available.
　上記焼結助剤は酸化イットリウム及び酸化アルミニウムを含有する。焼結助剤は粒状物であってよい。酸化イットリウムに対する酸化アルミニウムの質量比（酸化アルミニウムの含有量／酸化イットリウムの含有量の値）は、０．５未満である。これによって、窒化アルミニウム焼結体における酸化物の凝集を抑制することができる。酸化イットリウム及び酸化アルミニウムの配合割合は上述の範囲内で調整することができ、これによって窒化アルミニウム焼結体における酸化物の組成を調整することもできる。酸化アルミニウム及び酸化イットリウムは、焼結の際に、複合酸化物の液相を形成して焼結を促進する。これによって、窒化アルミニウム焼結体を十分に緻密化させることができる。 The sintering aid contains yttrium oxide and aluminum oxide. The sintering aid may be particulate. The mass ratio of aluminum oxide to yttrium oxide (content of aluminum oxide/content of yttrium oxide) is less than 0.5. Thereby, aggregation of oxides in the aluminum nitride sintered body can be suppressed. The mixing ratio of yttrium oxide and aluminum oxide can be adjusted within the range described above, thereby adjusting the oxide composition in the aluminum nitride sintered body. Aluminum oxide and yttrium oxide form a liquid phase of a composite oxide during sintering to promote sintering. Thereby, the aluminum nitride sintered body can be sufficiently densified.
　上記焼結助剤の含有量は、窒化アルミニウム１００質量部に対して、例えば、１～１０．０質量部であってよい。焼結剤の含有量を上記範囲内とすることで、得られる窒化アルミニウム焼結体の密度を向上させ、曲げ強さをより向上させることができる。焼結助剤の含有量を上記範囲内とすることでまた、得られる窒化アルミニウム焼結体の熱伝導率を向上させることができる。上記焼結助剤の含有量は焼結助剤の酸化物換算量で計算した値である。 The content of the sintering aid may be, for example, 1 to 10.0 parts by mass with respect to 100 parts by mass of aluminum nitride. By setting the content of the sintering agent within the above range, the density of the obtained aluminum nitride sintered body can be improved, and the bending strength can be further improved. By setting the content of the sintering aid within the above range, the thermal conductivity of the obtained aluminum nitride sintered body can be improved. The content of the sintering aid is a value calculated from the amount of the sintering aid in terms of oxide.
　また、酸化アルミニウムの含有量は、窒化アルミニウム１００質量部に対して、例えば、０．１～５．０質量部であってよい。酸化アルミニウムの含有量を０．１質量部以上とすることで、得られる焼結体の密度をより向上させることができる。また酸化アルミニウムの含有量を５．０質量部以下とすることで、窒化アルミニウムの相対的な含有割合を増加させることができ、得られる焼結体の熱伝導率の低下をより抑制することができる。 Also, the content of aluminum oxide may be, for example, 0.1 to 5.0 parts by mass with respect to 100 parts by mass of aluminum nitride. By setting the content of aluminum oxide to 0.1 parts by mass or more, the density of the obtained sintered body can be further improved. In addition, by setting the content of aluminum oxide to 5.0 parts by mass or less, the relative content of aluminum nitride can be increased, and the decrease in the thermal conductivity of the obtained sintered body can be further suppressed. can.
　窒化アルミニウム、焼結助剤及び必要に応じて添加される添加剤は、配合して混合し、成形原料として用いてよい。成形原料をドクターブレード法等の公知の方法によって例えばシート状に成形する。得られた成形体の脱脂を行ってもよい。脱脂方法は特に限定されず、例えば、成形体を空気中又は窒素等の非酸化雰囲気中で３００～７００℃に加熱して行ってよい。加熱時間は、例えば１～１０時間であってよい。 The aluminum nitride, the sintering aid, and the additive added as necessary may be blended and mixed and used as a forming raw material. The forming raw material is formed, for example, into a sheet by a known method such as a doctor blade method. The molded body obtained may be degreased. The degreasing method is not particularly limited, and for example, the compact may be heated to 300 to 700° C. in air or in a non-oxidizing atmosphere such as nitrogen. The heating time may be, for example, 1 to 10 hours.
　窒化アルミニウム焼結体は、上述の成形体を焼成して得ることができる。焼成の工程（以下、焼成工程ともいう）は、不活性ガス雰囲気中で行ってよい。不活性ガスとしては、例えば、窒素等であってよい。焼成工程は、大気圧下で行ってもよい。 The aluminum nitride sintered body can be obtained by firing the above compact. The baking step (hereinafter also referred to as the baking step) may be performed in an inert gas atmosphere. The inert gas may be, for example, nitrogen or the like. The firing step may be performed under atmospheric pressure.
　上記焼成工程は、１５００～１７００℃で１時間以上加熱することによって、上記成形体から第一焼成体を得る工程（以下、第一焼成工程ともいう）と、１７００℃超１８５０℃以下で１時間以上加熱することによって、上記第一焼成体から上記焼結体を得る工程（以下、第二焼成工程ともいう）と、を含む。 The firing step includes a step of obtaining a first fired body from the molded body by heating at 1500 to 1700 ° C. for 1 hour or more (hereinafter also referred to as a first firing step), and a step of heating at more than 1700 ° C. and 1850 ° C. or less for 1 hour. and a step of obtaining the sintered body from the first sintered body by heating as described above (hereinafter also referred to as a second sintering step).
　第一焼成工程の焼成温度は、焼結助剤の組成等によって選択することができ、例えば、１６５０℃以上、又は１６８０℃以上であってよい。第一焼成工程の上記焼成温度に到達するまでの昇温速度は比較的大きくてよく、例えば、２０℃／分以上、又は３０℃／分以上あってよい。第一焼成工程で、好ましくは上記焼成温度に所定時間保持する。第一焼成工程における焼成時間は、例えば、１．０時間以上、２．０時間以上、又は２．５時間以上であってよい。 The firing temperature in the first firing step can be selected depending on the composition of the sintering aid, and may be, for example, 1650°C or higher, or 1680°C or higher. The rate of temperature increase until the firing temperature in the first firing step is reached may be relatively high, for example, 20° C./min or more, or 30° C./min or more. In the first sintering step, the sintering temperature is preferably maintained for a predetermined period of time. The firing time in the first firing step may be, for example, 1.0 hours or longer, 2.0 hours or longer, or 2.5 hours or longer.
　第二焼成工程の焼成温度は、得られる焼結体の組織密度を向上させ、且つ表層における助剤の抜けを抑制する観点から、例えば、１８５０℃未満、１８４０℃未満、又は１８３０℃以下であってよい。第二焼成工程の上記焼成温度に到達するまでの昇温速度は、例えば、０．５℃／分以上、又は１．０℃／分以上であってよい。第二焼成工程で、好ましくは上記焼成温度に所定時間保持する。第二焼成工程における焼成時間は、例えば、１．０時間以上、１．５時間以上、又は２．０時間以上であってよい。 The firing temperature in the second firing step is, for example, less than 1850°C, less than 1840°C, or 1830°C or less from the viewpoint of improving the texture density of the obtained sintered body and suppressing the removal of the auxiliary agent from the surface layer. you can The rate of temperature increase until reaching the firing temperature in the second firing step may be, for example, 0.5° C./min or more, or 1.0° C./min or more. In the second sintering step, the sintering temperature is preferably maintained for a predetermined period of time. The firing time in the second firing step may be, for example, 1.0 hours or longer, 1.5 hours or longer, or 2.0 hours or longer.
　本明細書における焼成時間とは、上記成形体等の焼成対象物の置かれる雰囲気の温度が、上記焼成温度に到達してから、その温度に保持する時間を意味する。 The term "firing time" as used herein refers to the time during which the temperature of the atmosphere in which the object to be fired, such as the molded article, is placed reaches the firing temperature and is maintained at that temperature.
　上記焼成工程における第一焼成工程及び第二焼成工程の合計の焼成時間は、１４．０時間以下であるが、例えば、１０．０時間以下、８．０時間以下、又は７．０時時間以下であってよい。焼成時間の合計を上記範囲内とすることによって、上記成形体又は窒化アルミニウム焼結体の表層における焼結助剤が成形体又は窒化アルミニウム焼結体の表面へと抜けることを低減することができ、表面粗さを低減することができる。上記焼成工程における第一焼成工程及び第二焼成工程の合計の焼成時間は、例えば、４．５時間以上、又は５．０時間以上であってよい。焼成時間の合計を上記範囲内とすることによって、焼結助剤を溶融させ、窒化アルミニウムの粒子の溶解を十分なものとし、より均一な環境で窒化アルミニウムの粒子の成長を行うことができるため一層均一な粒度分布、及びより一層の緻密化構造を有する窒化アルミニウム焼結体を調製することができる。上記焼成工程の焼成時間は上述の範囲内で調整でき、例えば、５．０～８．０時間であってよい。 The total firing time of the first firing step and the second firing step in the firing step is 14.0 hours or less, but for example, 10.0 hours or less, 8.0 hours or less, or 7.0 hours or less. can be By setting the total firing time within the above range, it is possible to reduce the leakage of the sintering aid from the surface layer of the molded body or aluminum nitride sintered body to the surface of the molded body or aluminum nitride sintered body. , the surface roughness can be reduced. The total firing time of the first firing step and the second firing step in the firing step may be, for example, 4.5 hours or longer, or 5.0 hours or longer. By setting the total firing time within the above range, the sintering aid can be melted, the aluminum nitride particles can be sufficiently dissolved, and the aluminum nitride particles can grow in a more uniform environment. An aluminum nitride sintered body with a more uniform grain size distribution and a more dense structure can be prepared. The firing time of the firing step can be adjusted within the range described above, and may be, for example, 5.0 to 8.0 hours.
　上述の製造方法によって得られた窒化アルミニウム焼結体は、必要に応じて所望の形状に加工してもよい。窒化アルミニウム焼結体は、例えば、板状に加工され、窒化アルミニウム板とされてもよい。窒化アルミニウム板に金属回路又は金属板等の金属部を取り付けて基板としてもよい。基板は、例えば、窒化アルミニウム板の主面と銅板等の金属板の主面とを接合した積層基板であってよい。また、金属板の一部をエッチング等によって除去して導体部となる回路パターンが形成された回路基板であってもよい。このように、本開示の基板は、積層基板であってよく、回路基板であってもよい。板状の場合、窒化アルミニウム焼結体の厚みの下限値は、例えば、０．１０ｍｍ以上、０．２０ｍｍ以上、又は０．２５ｍｍ以上であってよい。板状の場合、窒化アルミニウム焼結体の厚みの上限値は、例えば、３．００ｍｍ以下、１．５０ｍｍｍ以下、又は１．００ｍｍ以下であってよい。窒化アルミニウム焼結体の厚みは上述の範囲内で調整することができ、例えば、０．１０～３．００ｍｍ、又は０．２５～１．００ｍｍであってよい。窒化アルミニウム焼結体の厚みを上述の範囲内とすることで、回路基板全体の放熱特性及び熱抵抗率をより高水準で両立することができる。 The aluminum nitride sintered body obtained by the above manufacturing method may be processed into a desired shape as necessary. The aluminum nitride sintered body may be processed into, for example, a plate shape to form an aluminum nitride plate. A substrate may be formed by attaching a metal part such as a metal circuit or a metal plate to an aluminum nitride plate. The substrate may be, for example, a laminated substrate in which the main surface of an aluminum nitride plate and the main surface of a metal plate such as a copper plate are bonded together. Moreover, it may be a circuit board having a circuit pattern formed by removing a part of a metal plate by etching or the like to form a conductor portion. Thus, the substrate of the present disclosure may be a laminate substrate or a circuit substrate. In the case of a plate shape, the lower limit of the thickness of the aluminum nitride sintered body may be, for example, 0.10 mm or more, 0.20 mm or more, or 0.25 mm or more. In the case of a plate shape, the upper limit of the thickness of the aluminum nitride sintered body may be, for example, 3.00 mm or less, 1.50 mm or less, or 1.00 mm or less. The thickness of the aluminum nitride sintered body can be adjusted within the above range, and may be, for example, 0.10-3.00 mm, or 0.25-1.00 mm. By setting the thickness of the aluminum nitride sintered body within the above range, it is possible to achieve both the heat dissipation characteristics and the thermal resistivity of the entire circuit board at a higher level.
　積層基板の一実施形態は、上述の窒化アルミニウム焼結体と、当該窒化アルミニウム焼結体に取り付けられている金属板と、を備える。図２は、積層基板の一例を示す斜視図である。積層基板２００は、互いに対向するように配置された一対の金属板１１０と、一対の金属板１１０の間に窒化アルミニウム焼結体で構成されるセラミック板１００と、を備える。金属板１１０としては、例えば、銅板等が挙げられる。セラミック板１００と、金属板１１０の形状及びサイズは同じであってもよいし、異なっていてもよい。金属板１１０とセラミック板１００は、例えば、ろう材によって接合されていてもよい。一対の金属板１１０の一方を放熱材とし、他方を回路パターンに加工してもよい。回路パターンは、レジストを用いて金属板１１０をエッチングして形成してもよい。これによって、漏れ電流等を十分に抑制することが可能な回路基板を形成したり、放熱基板を形成したりすることができる。 An embodiment of the laminated substrate comprises the aluminum nitride sintered body described above and a metal plate attached to the aluminum nitride sintered body. FIG. 2 is a perspective view showing an example of a laminated substrate. The laminated substrate 200 includes a pair of metal plates 110 arranged to face each other, and a ceramic plate 100 made of an aluminum nitride sintered body between the pair of metal plates 110 . Examples of the metal plate 110 include a copper plate. The shape and size of the ceramic plate 100 and the metal plate 110 may be the same or different. The metal plate 110 and the ceramic plate 100 may be joined by, for example, brazing material. One of the pair of metal plates 110 may be used as a heat dissipation material, and the other may be processed into a circuit pattern. The circuit pattern may be formed by etching the metal plate 110 using a resist. As a result, it is possible to form a circuit board capable of sufficiently suppressing leakage current or the like, or to form a heat dissipation board.
　回路基板の一実施形態は、上述の窒化アルミニウム焼結体と、当該窒化アルミニウム焼結体に取り付けられている導体部と、を備える。図３は、回路基板の一例を示す斜視図である。回路基板３００は、セラミック板１００と、複数の導体部２０と、金属板１１０と、を備える。導体部２０は、セラミック板１００の一方面１００Ａ上に設けられ、金属板１１０は、セラミック板１００の他方面に設けられる。回路基板３００をパワーモジュールに用いた場合に、金属板１１０は、放熱材として機能してもよい。 An embodiment of a circuit board includes the aluminum nitride sintered body described above and a conductor portion attached to the aluminum nitride sintered body. FIG. 3 is a perspective view showing an example of a circuit board. The circuit board 300 includes a ceramic plate 100 , a plurality of conductor portions 20 and a metal plate 110 . The conductor portion 20 is provided on one surface 100A of the ceramic plate 100, and the metal plate 110 is provided on the other surface of the ceramic plate 100. As shown in FIG. When the circuit board 300 is used for a power module, the metal plate 110 may function as a heat dissipation material.
　積層基板２００及び回路基板３００におけるセラミック板１００は、電気絶縁性及び熱伝導性に優れる窒化アルミニウム焼結体で構成される。このため、パワーモジュール等の種々の製品に用いたときに優れた信頼性を有する。 The ceramic plate 100 in the laminated board 200 and the circuit board 300 is composed of an aluminum nitride sintered body with excellent electrical insulation and thermal conductivity. Therefore, it has excellent reliability when used in various products such as power modules.
　以上、本開示の幾つかの実施形態について説明したが、本開示は上記実施形態に何ら限定されるものではない。例えば、本開示の基板の形状及び構造は、図２及び図３のものに限定されない。例えば、セラミック板１００の両方の主面に、回路パターンが形成されていてもよい。また、導体部２０は、金属板１１０をエッチングして形成することに代えて、金属粉末を溶射し熱処理することによって形成してもよい。また、上述した実施形態についての説明内容は、互いに適用することができる。 Although several embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments. For example, the shape and structure of the substrates of the present disclosure are not limited to those of FIGS. For example, circuit patterns may be formed on both main surfaces of the ceramic plate 100 . Also, instead of etching the metal plate 110, the conductor portion 20 may be formed by spraying metal powder and heat-treating it. Also, the descriptions of the above-described embodiments can be applied to each other.
　以下、本開示について、実施例及び比較例を用いてより詳細に説明する。なお、本開示は以下の実施例に限定されるものではない。 Hereinafter, the present disclosure will be described in more detail using examples and comparative examples. It should be noted that the present disclosure is not limited to the following examples.
（実施例１）
（窒化アルミニウム焼結体の作製）
　窒化アルミニウムの粉末１００質量部に対して、焼結助剤として酸化イットリウムの粉末６．０質量部、及びα－酸化アルミニウム０．３質量部を配合し、ボールミルを用いて混合して混合粉末を得た。混合粉末１００質量部に対し、セルロースエーテル系バインダー（信越化学工業株式会社製、商品名：メトローズ）を６質量部、グリセリン（花王株式会社製、商品名：エキセパール）を５質量部、及びイオン交換水を１０質量部添加して、ヘンシェルミキサーを用いて１分間混合し、成形原料を得た。 (Example 1)
(Preparation of Aluminum Nitride Sintered Body)
To 100 parts by mass of aluminum nitride powder, 6.0 parts by mass of yttrium oxide powder and 0.3 parts by mass of α-aluminum oxide are blended as sintering aids and mixed using a ball mill to obtain a mixed powder. Obtained. For 100 parts by mass of the mixed powder, 6 parts by mass of cellulose ether binder (manufactured by Shin-Etsu Chemical Co., Ltd., trade name: Metrose), 5 parts by mass of glycerin (manufactured by Kao Corporation, trade name: Excepar), and ion exchange 10 parts by mass of water was added and mixed for 1 minute using a Henschel mixer to obtain a molding raw material.
　この成形原料を、スクリュー式押出成型機によって成形し、シート状の成形体（幅：８０ｍｍ、厚み：０．８ｍｍ）を作製し、１００℃で１時間乾燥した後、裁断して、縦：６０ｍｍ×横：６０ｍｍ形状の成形体を得た。この成形体に、離型剤として窒化ホウ素粉を塗布した後、複数の上記積層体を積層試、積層体の質量が９５ｋｇとなるように調整した。得られた積層体を、空気中において５７０℃で１０時間加熱して脱脂し、脱脂体を得た。 This molding raw material is molded with a screw type extruder to produce a sheet-like molded body (width: 80 mm, thickness: 0.8 mm), dried at 100 ° C. for 1 hour, and then cut into a length of 60 mm. x Width: 60 mm shaped compact was obtained. After applying boron nitride powder as a release agent to this compact, a plurality of the laminates were laminated and the mass of the laminate was adjusted to 95 kg. The resulting laminate was degreased by heating in air at 570° C. for 10 hours to obtain a degreased body.
　次に、脱脂体を、加熱炉に入れて、窒素ガス雰囲気中で、大気圧下、２０℃／分の昇温速度で２５℃から１７００まで昇温し、１７００で２．０時間保持した（第一焼成工程）。次に、５℃／分の昇温速度で、１８３０℃まで昇温し、１８３０℃で８時間保持した（第二焼成工程）。その後、加熱を停止し、加熱炉内で放冷することによって、窒化アルミニウム焼結体を得た。 Next, the degreased body was placed in a heating furnace and heated from 25° C. to 1700 at a rate of 20° C./min under atmospheric pressure in a nitrogen gas atmosphere, and held at 1700 for 2.0 hours ( first firing step). Next, the temperature was raised to 1830° C. at a rate of temperature rise of 5° C./min and held at 1830° C. for 8 hours (second firing step). After that, the heating was stopped and the aluminum nitride sintered body was obtained by standing to cool in the heating furnace.
＜窒化アルミニウム焼結体の物性測定＞
　得られた窒化アルミニウム焼結体について、窒化アルミニウム粒子のｄ５０（平均粒子径）及びｄ９０、並びに焼結助剤粒子の総量、及び焼結助剤粒子の平均粒子径を測定した。結果を表１に示す。 <Measurement of physical properties of aluminum nitride sintered body>
For the obtained aluminum nitride sintered body, d50 (average particle size) and d90 of aluminum nitride particles, the total amount of sintering aid particles, and the average particle size of sintering aid particles were measured. Table 1 shows the results.
＜窒化アルミニウム焼結体の評価＞
　得られた窒化アルミニウム焼結体の曲げ強さ及び曲げ強さの分布（ワイブル係数）を測定した。窒化アルミニウム焼結体の曲げ強さは、ＪＩＳ　Ｃ　２１４１：１９９２「電気絶縁用セラミック材料試験方法」に記載の方法に準拠して測定した。また、得られた曲げ強さの結果に基づいてワイブルプロットを作成し、ワイブル係数を決定した。結果を表１に示す。 <Evaluation of Aluminum Nitride Sintered Body>
The flexural strength and the flexural strength distribution (Weibull modulus) of the obtained aluminum nitride sintered body were measured. The flexural strength of the aluminum nitride sintered body was measured according to the method described in JIS C 2141:1992 "Electrical insulating ceramic material test method". In addition, a Weibull plot was created based on the bending strength obtained, and the Weibull coefficient was determined. Table 1 shows the results.
（実施例２）
　第一焼成工程における昇温速度を３０℃／分に、焼成時間を１．０時間に変更したこと、及び、第二焼成工程における焼成温度を１８００℃に、焼成時間を１時間に変更したこと以外は、実施例１と同様にして、窒化アルミニウム焼結体を調製した。 (Example 2)
The heating rate in the first firing step was changed to 30°C/min and the firing time was changed to 1.0 hour, and the firing temperature in the second firing step was changed to 1800°C and the firing time was changed to 1 hour. An aluminum nitride sintered body was prepared in the same manner as in Example 1 except for the above.
（実施例３）
　第一焼成工程における焼成時間を８．０時間に変更したこと、及び、第二焼成工程における焼成温度を１８５０℃に、焼成時間を４時間に変更したこと以外は、実施例１と同様にして、窒化アルミニウム焼結体を調製した。 (Example 3)
In the same manner as in Example 1, except that the firing time in the first firing step was changed to 8.0 hours, and the firing temperature in the second firing step was changed to 1850 ° C. and the firing time was changed to 4 hours. , an aluminum nitride sintered body was prepared.
（実施例４）
　第二焼成工程において焼成温度を１８２０℃に、焼成時間を４時間に変更したこと以外は、実施例１と同様にして、窒化アルミニウム焼結体を調製した。 (Example 4)
An aluminum nitride sintered body was prepared in the same manner as in Example 1, except that the firing temperature was changed to 1820° C. and the firing time was changed to 4 hours in the second firing step.
（実施例５）
　第一焼成工程において焼成温度を１５００℃に、焼成時間を３時間に変更したこと、及び、第二焼成工程において焼成温度を１８００℃に、焼成時間を４時間に変更したこと以外は、実施例１と同様にして、窒化アルミニウム焼結体を調製した。 (Example 5)
In the first firing step, the firing temperature was changed to 1500 ° C. and the firing time was changed to 3 hours, and in the second firing step, the firing temperature was changed to 1800 ° C. and the firing time was changed to 4 hours. An aluminum nitride sintered body was prepared in the same manner as in 1.
（実施例６）
　第二焼成工程において昇温速度を１℃／分に、焼成温度を１８４０℃に、焼成時間を２時間に変更したこと以外は、実施例１と同様にして、窒化アルミニウム焼結体を調製した。 (Example 6)
An aluminum nitride sintered body was prepared in the same manner as in Example 1, except that in the second firing step, the heating rate was changed to 1°C/min, the firing temperature was changed to 1840°C, and the firing time was changed to 2 hours. .
（実施例７）
　第二焼成工程において昇温速度を１℃／分に、焼成温度を１８３０℃に、焼成時間を２時間に変更したこと以外は、実施例１と同様にして、窒化アルミニウム焼結体を調製した。 (Example 7)
An aluminum nitride sintered body was prepared in the same manner as in Example 1, except that in the second firing step, the heating rate was changed to 1°C/min, the firing temperature was changed to 1830°C, and the firing time was changed to 2 hours. .
＜窒化アルミニウム焼結体の物性測定及び評価＞
　実施例２～７で得られた窒化アルミニウム焼結体について、実施例１と同様にして、窒化アルミニウム粒子のｄ５０（平均粒子径）及びｄ９０、並びに焼結助剤粒子の総量、及び焼結助剤粒子の平均粒子径を測定した。結果を表１に示す。 <Measurement and Evaluation of Physical Properties of Aluminum Nitride Sintered Body>
Regarding the aluminum nitride sintered bodies obtained in Examples 2 to 7, in the same manner as in Example 1, the d50 (average particle diameter) and d90 of the aluminum nitride particles, the total amount of sintering aid particles, and the sintering aid The average particle size of the agent particles was measured. Table 1 shows the results.
＜窒化アルミニウム焼結体の評価＞
　実施例２～７で得られた窒化アルミニウム焼結体について、実施例１と同様にして、曲げ強さ及び曲げ強さの分布（ワイブル係数）を測定した。結果を表１に示す。 <Evaluation of Aluminum Nitride Sintered Body>
For the aluminum nitride sintered bodies obtained in Examples 2 to 7, bending strength and bending strength distribution (Weibull coefficient) were measured in the same manner as in Example 1. Table 1 shows the results.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
（比較例１）
　第一焼成工程において昇温速度を３０℃／分に、焼成温度を１４５０℃に変更したこと、及び、第二焼成工程において昇温速度を０．３℃／分に、焼成温度を１９００℃に、焼成時間を２時間に変更したこと以外は、実施例１と同様にして、窒化アルミニウム焼結体を得た。 (Comparative example 1)
The heating rate was changed to 30°C/min and the firing temperature to 1450°C in the first firing step, and the heating rate was changed to 0.3°C/min and the firing temperature to 1900°C in the second firing step. A sintered body of aluminum nitride was obtained in the same manner as in Example 1, except that the firing time was changed to 2 hours.
（比較例２）
　第二焼成工程において昇温速度を５℃／分に、焼成温度を１８７０℃に、焼成時間を１０時間に変更したこと以外は、比較例１と同様にして、窒化アルミニウム焼結体を調製した。 (Comparative example 2)
An aluminum nitride sintered body was prepared in the same manner as in Comparative Example 1, except that in the second firing step, the heating rate was changed to 5°C/min, the firing temperature was changed to 1870°C, and the firing time was changed to 10 hours. .
（比較例３）
　第一焼成工程において昇温速度を１０℃／分に、焼成温度を１７５０℃に、焼成時間を８時間に変更したこと、及び、第二焼成工程において昇温速度を５．０℃／分に、焼成温度を１８７０℃に変更したこと以外は、比較例１と同様にして、窒化アルミニウム焼結体を調製した。 (Comparative Example 3)
In the first firing step, the temperature increase rate was changed to 10°C/min, the firing temperature was changed to 1750°C, and the firing time was changed to 8 hours, and in the second firing step, the temperature increase rate was changed to 5.0°C/min. , an aluminum nitride sintered body was prepared in the same manner as in Comparative Example 1, except that the sintering temperature was changed to 1870°C.
（比較例４）
　第一焼成工程において昇温速度を４０℃／分に、焼成温度を１７５０℃に、焼成時間を０．５時間に変更したこと、及び、第二焼成工程において昇温速度を１０℃／分に、焼成温度を１８００℃に変更したこと以外は、比較例１と同様にして、窒化アルミニウム焼結体を調製した。 (Comparative Example 4)
In the first firing step, the temperature rise rate was changed to 40°C/min, the firing temperature was changed to 1750°C, and the firing time was changed to 0.5 hours, and in the second firing step, the temperature rise rate was changed to 10°C/min. , an aluminum nitride sintered body was prepared in the same manner as in Comparative Example 1, except that the sintering temperature was changed to 1800°C.
＜窒化アルミニウム焼結体の物性測定及び評価＞
　比較例２～４で得られた窒化アルミニウム焼結体について、実施例１と同様にして、窒化アルミニウム粒子のｄ５０（平均粒子径）及びｄ９０、並びに焼結助剤粒子の総量、及び焼結助剤粒子の平均粒子径を測定した。結果を表２に示す。 <Measurement and Evaluation of Physical Properties of Aluminum Nitride Sintered Body>
Regarding the aluminum nitride sintered bodies obtained in Comparative Examples 2 to 4, in the same manner as in Example 1, the d50 (average particle diameter) and d90 of the aluminum nitride particles, the total amount of sintering aid particles, and the sintering aid The average particle size of the agent particles was measured. Table 2 shows the results.
＜窒化アルミニウム焼結体の評価＞
　比較例２～４で得られた窒化アルミニウム焼結体について、実施例１と同様にして、曲げ強さ及び曲げ強さの分布（ワイブル係数）を測定した。結果を表２に示す。 <Evaluation of Aluminum Nitride Sintered Body>
For the aluminum nitride sintered bodies obtained in Comparative Examples 2 to 4, bending strength and bending strength distribution (Weibull coefficient) were measured in the same manner as in Example 1. Table 2 shows the results.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　本開示によれば、曲げ強さに優れる窒化アルミニウム焼結体及びその製造方法を提供できる。本開示によればまた、上記窒化アルミニウム焼結体を備え、接続信頼性に優れる積層基板及び回路基板を提供できる。 According to the present disclosure, an aluminum nitride sintered body with excellent bending strength and a method for producing the same can be provided. According to the present disclosure, it is also possible to provide a laminated substrate and a circuit substrate that are equipped with the aluminum nitride sintered body and have excellent connection reliability.
　２０…導体部、１００…セラミック板（窒化アルミニウム焼結体）、１１０…金属板、２００…積層基板、３００…回路基板。 20... conductor portion, 100... ceramic plate (aluminum nitride sintered body), 110... metal plate, 200... laminated substrate, 300... circuit board.

Claims (7)

  1. 　窒化アルミニウム粒子と、焼結助剤粒子と、を含み、
    　前記窒化アルミニウム粒子の平均粒子径が２．０～１０．０μｍであり、
    　厚み方向に水平な断面における、
    　　表面層の前記焼結助剤粒子の総量をＡ面積％とし、中間層の前記焼結助剤粒子の総量をＢ面積％としたときの、Ｂ－Ａの値が６．０面積％以下であり、
    　　表面層の前記焼結助剤粒子の平均粒子径をＣμｍとし、中間層の前記焼結助剤粒子の平均粒子径をＤμｍとしたときの、Ｄ－Ｃが４．０μｍ以下である、窒化アルミニウム焼結体。     including aluminum nitride particles and sintering aid particles,
    The aluminum nitride particles have an average particle size of 2.0 to 10.0 μm,
    In a cross section horizontal to the thickness direction,
    When the total amount of the sintering aid particles in the surface layer is A area% and the total amount of the sintering aid particles in the intermediate layer is B area%, the value of BA is 6.0 area% or less. can be,
    Aluminum nitride having a DC of 4.0 μm or less, where C μm is the average particle diameter of the sintering aid particles in the surface layer and D μm is the average particle diameter of the sintering aid particles in the intermediate layer. Sintered body.
  2. 　主面における前記焼結助剤粒子の総量が４．０面積％未満である、請求項１に記載の窒化アルミニウム焼結体。 The aluminum nitride sintered body according to claim 1, wherein the total amount of the sintering aid particles on the main surface is less than 4.0 area%.
  3. 　前記窒化アルミニウム粒子に対する電子顕微鏡画像解析によって測定される粒子径の累積頻度分布曲線において、小粒径からの積算値が全体の９０％に達した時の粒子径をｄ９０としたときに、ｄ９０が１３．０μｍ以下である、請求項１又は２に記載の窒化アルミニウム焼結体。 In the cumulative frequency distribution curve of particle diameters measured by electron microscope image analysis for the aluminum nitride particles, when the particle diameter when the integrated value from the small particle diameter reaches 90% of the total is d90, d90 is The aluminum nitride sintered body according to claim 1 or 2, which has a thickness of 13.0 µm or less.
  4. 　前記窒化アルミニウム粒子に対する電子顕微鏡画像解析によって測定される粒子径の累積頻度分布曲線において、小粒径からの積算値が全体の９０％に達した時の粒子径を、ｄ９０としたときに、前記ｄ９０と前記平均粒子径との差が１．０～３．５μｍである、請求項１～３のいずれか一項に記載の窒化アルミニウム焼結体。 In the cumulative frequency distribution curve of the particle size measured by electron microscope image analysis for the aluminum nitride particles, when the particle size when the integrated value from the small particle size reaches 90% of the total is d90, the above The aluminum nitride sintered body according to any one of claims 1 to 3, wherein the difference between d90 and said average particle size is 1.0 to 3.5 µm.
  5. 　請求項１～４のいずれか一項に記載の窒化アルミニウム焼結体と、当該窒化アルミニウム焼結体に取り付けられている導体部と、を備える、回路基板。 A circuit board comprising the aluminum nitride sintered body according to any one of claims 1 to 4 and a conductor part attached to the aluminum nitride sintered body.
  6. 　請求項１～４のいずれか一項に記載の窒化アルミニウム焼結体と、当該窒化アルミニウム焼結体に取り付けられている金属板と、を備える、積層基板。 A laminated substrate comprising the aluminum nitride sintered body according to any one of claims 1 to 4 and a metal plate attached to the aluminum nitride sintered body.
  7. 　窒化アルミニウム及び焼結助剤を含む混合物で構成される成形体を焼成して焼結体を得る焼成工程を有し、
    　前記焼結助剤は酸化イットリウム及び酸化アルミニウムを含有し、
    　前記酸化イットリウムに対する前記酸化アルミニウムの質量比が０．５未満であり、
    　前記焼成工程は、
    　　１５００～１７００℃で１時間以上加熱することによって、前記成形体から第一焼成体を得る工程と、
    　　１７００℃超１８５０℃以下で１時間以上加熱することによって、前記第一焼成体から前記焼結体を得る工程と、を含み、
    　前記焼成工程の焼成時間は１４．０時間以下である、窒化アルミニウム焼結体の製造方法。     A firing step of firing a molded body composed of a mixture containing aluminum nitride and a sintering aid to obtain a sintered body,
    The sintering aid contains yttrium oxide and aluminum oxide,
    The mass ratio of the aluminum oxide to the yttrium oxide is less than 0.5,
    The firing step includes
    a step of obtaining a first fired body from the molded body by heating at 1500 to 1700° C. for 1 hour or more;
    a step of obtaining the sintered body from the first fired body by heating at more than 1700 ° C. and 1850 ° C. or less for 1 hour or more,
    A method for producing an aluminum nitride sintered body, wherein the firing time in the firing step is 14.0 hours or less.
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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0524930A (en) * 1991-07-16 1993-02-02 Showa Denko Kk Aln sintered compact and production thereof
JPH05226795A (en) * 1992-02-17 1993-09-03 Ibiden Co Ltd Manufacture of aluminum nitride substrate
JP2001002474A (en) * 1999-06-17 2001-01-09 Denki Kagaku Kogyo Kk Aluminum nitride sintered body and its production and use
JP2005075695A (en) * 2003-09-02 2005-03-24 Denki Kagaku Kogyo Kk Aluminum nitride sintered compact and method of manufacturing the same
JP2010183096A (en) * 2010-03-23 2010-08-19 Toshiba Corp Ceramic copper circuit board and semiconductor device
JP2011111341A (en) * 2009-11-25 2011-06-09 Panasonic Electric Works Co Ltd Aluminum nitride substrate having oxidized layer, method for producing the substrate, circuit board obtained by using the substrate, and led module
JP2018070433A (en) * 2016-11-02 2018-05-10 株式会社Maruwa Aluminum nitride sintered body and method for producing the same

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0524930A (en) * 1991-07-16 1993-02-02 Showa Denko Kk Aln sintered compact and production thereof
JPH05226795A (en) * 1992-02-17 1993-09-03 Ibiden Co Ltd Manufacture of aluminum nitride substrate
JP2001002474A (en) * 1999-06-17 2001-01-09 Denki Kagaku Kogyo Kk Aluminum nitride sintered body and its production and use
JP2005075695A (en) * 2003-09-02 2005-03-24 Denki Kagaku Kogyo Kk Aluminum nitride sintered compact and method of manufacturing the same
JP2011111341A (en) * 2009-11-25 2011-06-09 Panasonic Electric Works Co Ltd Aluminum nitride substrate having oxidized layer, method for producing the substrate, circuit board obtained by using the substrate, and led module
JP2010183096A (en) * 2010-03-23 2010-08-19 Toshiba Corp Ceramic copper circuit board and semiconductor device
JP2018070433A (en) * 2016-11-02 2018-05-10 株式会社Maruwa Aluminum nitride sintered body and method for producing the same

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