Aluminum nitride powder, aluminum nitride sintered body, circuit board, and bonded board

Abstract

To provide aluminum nitride powder with improved thermal conductivity.SOLUTION: An aluminum nitride powder comprises aluminum nitride particles, wherein the aluminum nitride powder has a peak in each of a range (A) of wave number 150 cm-1 or more and 350 cm-1 or less and a range (B) of wave number 800 cm-1 or more and 1000 cm-1 or less in a Raman spectroscopic spectrum measured under the following conditions: (Conditions) Laser wavelength: 532 nm, Objective lens magnification: 20-fold, Grating: 300 Gr / mm, Slit width: 50 μm, Exposure time: 1 second, Number of exposures: 10 times.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to aluminum nitride powder, an aluminum nitride sintered body, a circuit board, and a bonding board.

Background Art

[0002] A sintered body containing aluminum nitride powder may be used for a circuit board or a bonding board. Patent Document 1 aims to provide aluminum nitride powder that is extremely low in oxygen compared to conventional products and exhibits excellent high thermal conductivity when used as a filler for a heat dissipation member. The aluminum nitride powder is obtained by heating hollow aluminum nitride particles in a reducing atmosphere containing nitrogen at 1900°C to 2200°C, and has an oxygen content of 0.2% by mass or less and an average particle diameter of 10 to 50 μm.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention provides aluminum nitride powder with improved thermal conductivity.

Means for Solving the Problems

[0005] The inventors of the present invention have intensively studied to solve the above problems. As a result, an aluminum nitride powder containing aluminum nitride particles, wherein in the Raman spectrum measured under specific conditions for the aluminum nitride powder, the wavenumber is 150 cm -1 or more and 350 cm -1 or less in the range (A) and 800 cm -1 or more and 1000 cm -1The present inventors have found that aluminum nitride powder having peaks in the following ranges (B) can improve thermal conductivity, and have completed the present invention.

[0006] According to the present invention, there are provided an aluminum nitride powder, an aluminum nitride sintered body, a circuit board, and a bonded substrate, as shown below.

[0007] [1] An aluminum nitride powder containing aluminum nitride particles, In the Raman spectrum of the aluminum nitride powder measured under the following conditions, the wave number is 150 cm -1 More than 350cm -1 The following ranges (A) and 800 cm -1 More than 1000cm -1 Aluminum nitride powder having peaks in the following ranges (B): (conditions) Laser wavelength: 532nm Objective lens magnification: 20x Grating: 300Gr / mm Slit width: 50 μm Exposure time: 1 second Number of exposures: 10 [2] In the Raman spectrum, the wave number is 500 cm -1 More than 750cm -1 The peak intensity I of the maximum peak in the range (X) below X The wave number is 1250 cm -1 More than 1450cm -1 The peak intensity I of the maximum peak in the following range (C) C Ratio of I C / I X The aluminum nitride powder according to [1], wherein the value of σ is 0.020 or less. [3] The aluminum nitride powder according to [2], wherein the Raman spectrum does not have a peak in the range (C). [4] In the Raman spectrum, the wave number is 500 cm -1 More than 750cm-1 The peak intensity I of the maximum peak in the following range (X) X with respect to the wavenumber of 1500 cm -1 or more and 1700 cm -1 or less in the following range (D), the peak intensity I of the maximum peak D of the ratio I D / I X is 0.020 or less, the aluminum nitride powder according to any one of [1] to [3]. [5] In the Raman spectrum, the aluminum nitride powder according to [4] having no peak in the range (D). [6] In the Raman spectrum, with respect to the peak intensity I of the maximum peak in the range (X) where the wavenumber is 500 cm -1 or more and 750 cm -1 or less, the peak intensity I of the maximum peak in the following range (A) X of the ratio I A / I A is 0.020 or more and 0.200 or less, the aluminum nitride powder according to any one of [1] to [5]. X [7]In the Raman spectrum, with respect to the peak intensity I of the maximum peak in the range (X) where the wavenumber is 500 cm -1 or more and 750 cm -1 or less, the peak intensity I of the maximum peak in the following range (B) X B of the ratio I B / I X is 0.030 or more and 0.400 or less, the aluminum nitride powder according to any one of [1] to [6]. -1 [8]In the Raman spectrum, the aluminum nitride powder according to any one of [1] to [7] further having two or more peaks in the range (X) where the wavenumber is 500 cm -1 50 or more and 750 cm -1 or less. [9] The volume-based median diameter D of the aluminum nitride powder by the laser diffraction scattering method 50The aluminum nitride powder according to any one of [1] to [8], wherein the particle size is 0.50 μm or more and 5.00 μm or less.

[10] In the volume frequency particle size distribution of the aluminum nitride powder by the laser diffraction scattering method, the particle size D at which the cumulative value is 10% 10 , the particle size D at which the cumulative value is 90% 90 , and the median diameter D 50 For, (D 90 -D 10 ) / D 50 The value of is 3.00 or less, and the aluminum nitride powder according to any one of [1] to [9].

[11] The specific surface area measured by the BET single point method in accordance with ISO9277 of the aluminum nitride powder is 1.00 m 2 / g or more and 5.00 m 2 / g or less, and the aluminum nitride powder according to any one of [1] to

[10] .

[12] The amount of oxygen measured using an oxygen / nitrogen simultaneous analyzer in the aluminum nitride powder is 0.50 mass% or more and 0.90 mass% or less, and the aluminum nitride powder according to any one of [1] to

[11] .

[13] The aluminum nitride powder according to any one of [1] to

[12] , which contains hexagonal aluminum nitride primary particles.

[14] The thermal conductivity by the following method is 120 W / (m·K) or more, and the aluminum nitride powder according to any one of [1] to

[13] . (Method) A molding material is obtained by mixing 100 parts by weight of the aluminum nitride powder, 4 parts by weight of yttrium oxide powder, 3 parts by weight of aluminum oxide powder, 6 parts by weight of a cellulose ether binder, 5 parts by weight of glycerin, and 10 parts by weight of ion-exchanged water. The molding material is then formed into a sheet, degreased by heating in air at 570°C for 5 hours, and then heated under a nitrogen gas atmosphere at atmospheric pressure and 1800°C for 4 hours to obtain an aluminum nitride sintered body. The thermal conductivity of the aluminum nitride sintered body is then measured by the laser flash method at 23°C in accordance with JIS R1611:2010.

[15] An aluminum nitride sintered body comprising the aluminum nitride powder according to any one of [1] to

[14] .

[16] A circuit board comprising the aluminum nitride sintered body according to

[15] and a conductor portion.

[17]

[15] A bonded substrate comprising the aluminum nitride sintered body according to

[15] and a metal plate. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide aluminum nitride powder having improved thermal conductivity. [Brief explanation of the drawings]

[0009]

Figure 1

Figure 2

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, similar components are denoted by similar reference numerals and descriptions thereof will be omitted where appropriate. To avoid complexity, when there are multiple identical components in the same drawing, only one of them may be labeled with a symbol, and not all of them. The drawings are for illustrative purposes only. The shapes and dimensional ratios of the various components in the drawings do not necessarily correspond to those of actual articles.

[0011] In this embodiment, "A to B" indicating a numerical range represents A or more and B or less, unless otherwise specified.

[0012] <Aluminum nitride powder> The aluminum nitride powder of this embodiment is an aluminum nitride powder containing aluminum nitride particles, and in the Raman spectrum (S) measured under the following conditions, the wave number is 150 cm -1 or more and 350 cm -1 or less in the range (A) and 800 cm -1 or more and 1000 cm -1 or less in the range (B), respectively having peaks. (Condition) Laser wavelength: 532 nm Objective lens magnification: 20 times Gratings: 300 Gr / mm Slit width: 50 μm Exposure time: 1 second Number of exposures: 10 times

[0013] According to the study by the present inventor, in the aluminum nitride powder containing aluminum nitride particles, there is a correlation between the peaks in the range of the wave number of 150 cm -1 or more and 350 cm -1 or less in the Raman spectrum of the aluminum nitride powder and the thermal conductivity. -1 or more and 1000 cm -1 or less in the range and the thermal conductivity.

[0014] As a result of further studies by the present inventor based on the above findings, in the Raman spectrum measured under the conditions of a laser wavelength of 532 nm, an objective lens magnification of 20 times, gratings of 300 Gr / mm, a slit width of 50 μm, an exposure time of 1 second, and a number of exposures of 10 times, the wave number is 150 cm -1 or more and 350 cm -1 or less in the range (A) and 800 cm-1 above 1000 cm -1 By having peaks in the following range (B) respectively, it has been found that the thermal conductivity of aluminum nitride powder can be improved, and the present invention has been completed.

[0015] The aluminum nitride powder of the present embodiment preferably has one or more peaks in the range (X) where the wave number is 500 cm -1 or more and 750 cm -1 or less in the Raman spectrum (S), more preferably has two or more peaks in the range (X), still more preferably has three or more peaks in the range (X), and still more preferably has three peaks in the range (X).

[0016] In the Raman spectrum (S) of the aluminum nitride powder of the present embodiment, the peak intensity I of the maximum peak in the range (X) X is preferably the largest among the peak intensities of the peaks that the Raman spectrum (S) has.

[0017] In the Raman spectrum (S) of the aluminum nitride powder of the present embodiment, the magnitude of the peak intensity of each peak can be evaluated, for example, as a relative value with respect to the peak intensity I of the maximum peak in the range (X). X

[0018] In this specification, the peak intensity of the maximum peak in the range where the wave number in the Raman spectrum (S) is P (cm -1 ) or more and Q (cm -1 ) or less means the difference between the baseline and the scattering intensity of the maximum peak, with the average value of the scattering intensity at P (cm -1 ) and the scattering intensity at Q (cm -1 ) as the baseline.

[0019] In the Raman spectrum (S) of the aluminum nitride powder of the present embodiment, the peak intensity I of the maximum peak in the range (X) where the wave number is 500 cm -1 or more and 750 cm -1 or less X ​For the range (A) where the wave number is 150 cm -1 or more and 350 cm -1 or less, the peak intensity I A of the maximum peak A The ratio I X / I

[0020] In the Raman spectrum (S) of the aluminum nitride powder of the present embodiment, for the range (X) where the wave number is 500 cm -1 or more and 750 cm -1 or less, the peak intensity I X of the maximum peak -1 For the range (B) where the wave number is 800 cm -1 or more and 1000 cm B or less, the peak intensity I B of the maximum peak X The ratio I

[0021] In the Raman spectrum (S) of the aluminum nitride powder of the present embodiment, for the range (X) where the wave number is 500 cm -1 or more and 750 cm -1 or less, the peak intensity I X of the maximum peak -1 For the range (C) where the wave number is 1250 cm -1 or more and 1450 cm C or less, the peak intensity I C of the maximum peak Xis preferably 0.020 or less, more preferably 0.015 or less, still more preferably 0.010 or less, still more preferably 0.005 or less, and still more preferably 0.001 or less from the viewpoint of further improving thermal conductivity. In the Raman spectrum (S) of the aluminum nitride powder of the present embodiment, I C / I X The lower limit of is not particularly limited, and may be, for example, 0.000 or more.

[0022] In the Raman spectrum (S) of the aluminum nitride powder of the present embodiment, from the viewpoint of further improving thermal conductivity, it is more preferable that there is no peak in the range (C) where the wave number is 1250 cm -1 or more and 1450 cm -1 or less.

[0023] In the Raman spectrum (S) of the aluminum nitride powder of the present embodiment, the peak intensity I -1 of the maximum peak in the range (X) where the wave number is 500 cm -1 or more and 750 cm X or less, relative to the peak intensity I -1 of the maximum peak in the range (D) where the wave number is 1500 cm -1 or more and 1700 cm D or less, the ratio I D / I X is preferably 0.020 or less, more preferably 0.015 or less, still more preferably 0.010 or less, still more preferably 0.005 or less, and still more preferably 0.001 or less from the viewpoint of further improving thermal conductivity. In the Raman spectrum (S) of the aluminum nitride powder of the present embodiment, I C / I X The lower limit of is not particularly limited, and may be, for example, 0.000 or more.

[0024] In the Raman spectrum (S) of the aluminum nitride powder of the present embodiment, from the viewpoint of further improving thermal conductivity, it is more preferable that there is no peak in the range (D) where the wave number is 1500 cm -1 or more and 1700 cm -1 or less.

[0025] According to the study by the present inventors, in aluminum nitride powder containing aluminum nitride particles, the wave number in the Raman spectroscopy spectrum of the aluminum nitride powder is 1250 cm -1 More than 1450cm -1 Peaks in the range below and 1500 cm -1 More than 1700cm -1 It was found that there is a correlation between the peaks in the following range and thermal conductivity:

[0026] As a result of further investigations based on the above findings, the inventors have found that in a Raman spectrum measured under the conditions of a laser wavelength of 532 nm, an objective lens magnification of 20 times, a grating of 300 Gr / mm, a slit width of 50 μm, an exposure time of 1 second, and 10 exposures, the wavenumber is 1250 cm -1 More than 1450cm -1 The peak intensity I of the maximum peak in the following range (C) C or the wave number is 1500 cm -1 More than 1700cm -1 The peak intensity I of the maximum peak in the following range (D) D It has been found that the thermal conductivity of aluminum nitride powder can be further improved by reducing the SiO2 content.

[0027] From the viewpoint of further improving thermal conductivity, the aluminum nitride powder of this embodiment preferably contains aluminum nitride primary particles, and more preferably contains hexagonal aluminum nitride primary particles.

[0028] From the viewpoint of further improving thermal conductivity, the content of aluminum nitride particles in the aluminum nitride powder of this embodiment is preferably 80 mass % or more, more preferably 90 mass % or more, even more preferably 95 mass % or more, and even more preferably 99 mass % or more, when the total amount of the aluminum nitride powder is taken as 100 mass %. The upper limit of the content of aluminum nitride particles in the aluminum nitride powder of this embodiment is not particularly limited, but may be, for example, 100 mass % or less.

[0029] The volume-based median diameter D of the aluminum nitride powder of the present embodiment by the laser diffraction scattering method 50 is preferably 0.50 μm or more and 5.00 μm or less, more preferably 0.80 μm or more and 4.00 μm or less, still more preferably 1.00 μm or more and 3.50 μm or less, and still more preferably 1.50 μm or more and 3.00 μm or less from the viewpoint of further improving the performance balance between sinterability and moldability.

[0030] In the volume frequency particle size distribution of the aluminum nitride powder of the present embodiment by the laser diffraction scattering method, the particle diameter D at which the cumulative value becomes 10% 10 is preferably 0.10 μm or more and 3.00 μm or less, more preferably 0.20 μm or more and 2.00 μm or less, still more preferably 0.30 μm or more and 1.00 μm or less, still more preferably 0.35 μm or more and 0.80 μm or less, and still more preferably 0.40 μm or more and 0.60 μm or less from the viewpoint of further improving the performance balance between sinterability and moldability.

[0031] In the volume frequency particle size distribution of the aluminum nitride powder of the present embodiment by the laser diffraction scattering method, the particle diameter D at which the cumulative value becomes 90% 90 is preferably 1.00 μm or more and 20.00 μm or less, more preferably 2.00 μm or more and 15.00 μm or less, still more preferably 2.50 μm or more and 10.00 μm or less, still more preferably 3.50 μm or more and 8.00 μm or less, and still more preferably 4.50 μm or more and 6.00 μm or less from the viewpoint of further improving the performance balance between sinterability and moldability.

[0032] In the volume frequency particle size distribution of the aluminum nitride powder of the present embodiment by the laser diffraction scattering method, the particle diameter D at which the cumulative value becomes 10% 10 , the particle diameter D at which the cumulative value becomes 90% 90 , and the median diameter D 50 Regarding (D 90 -D 10 ) / D 50The value is preferably 3.00 or less, more preferably 2.70 or less, still more preferably 2.50 or less, still more preferably 2.30 or less, still more preferably 2.10 or less, and still more preferably 2.00 or less from the viewpoint of further improving the balance of sinterability and moldability performance. The (D 90 -D 10 ) / D 50 value of the aluminum nitride powder of the present embodiment has no particular lower limit, but may be, for example, 0.10 or more, 0.50 or more, 1.00 or more, 1.30 or more, 1.50 or more, or 1.70 or more.

[0033] The specific surface area of the aluminum nitride powder of the present embodiment measured by the BET single-point method in accordance with ISO9277 is preferably 1.00 m 2 / g or more and 5.00 m 2 / g or less, more preferably 1.30 m 2 / g or more and 4.00 m 2 / g or less, still more preferably 1.50 m 2 / g or more and 3.00 m 2 / g or less, still more preferably 1.70 m 2 / g or more and 2.70 m 2 / g or less, still more preferably 1.80 m 2 / g or more and 2.30 m 2 / g or less from the viewpoint of further improving the balance of sinterability and moldability performance.

[0034] The amount of oxygen measured using an oxygen / nitrogen simultaneous analyzer for the aluminum nitride powder of the present embodiment is preferably 0.50 mass% or more and 0.90 mass% or less, more preferably 0.55 mass% or more and 0.85 mass% or less, still more preferably 0.60 mass% or more and 0.80 mass% or less, and still more preferably 0.65 mass% or more and 0.75 mass% or less when the total amount of the aluminum nitride powder is 100 mass% from the viewpoint of further improving thermal conductivity.

[0035] The thermal conductivity of the aluminum nitride powder of the present embodiment by the following method is preferably 120 W / (m·K) or more, more preferably 130 W / (m·K) or more, still more preferably 140 W / (m·K) or more, still more preferably 150 W / (m·K) or more, still more preferably 155 W / (m·K) or more, and still more preferably 160 W / (m·K) or more from the viewpoint of further improving the thermal conductivity. The upper limit value of the thermal conductivity of the aluminum nitride powder of the present embodiment by the following method is not particularly limited, and may be, for example, 300 W / (m·K) or less, 250 W / (m·K) or less, or 200 W / (m·K) or less. (Method) 100 parts by mass of aluminum nitride powder, 4 parts by mass of yttrium oxide powder, 3 parts by mass of aluminum oxide powder, 6 parts by mass of cellulose ether binder, 5 parts by mass of glycerin, and 10 parts by mass of ion-exchanged water are mixed to obtain a molding material. Next, the molding material is formed into a sheet shape, heated at 570 °C for 5 hours in air for debinding, and then heated at 1800 °C for 4 hours under atmospheric pressure in a nitrogen gas atmosphere to obtain an aluminum nitride sintered body. Next, for the aluminum nitride sintered body, in accordance with JIS R1611:2010, the thermal conductivity is measured by the laser flash method under the condition of 23 °C.

[0036] <Manufacturing method of aluminum nitride powder> The aluminum nitride powder of the present embodiment can be obtained by appropriately selecting the selection of raw materials, the usage ratio of each raw material, the manufacturing procedure and manufacturing conditions, etc. Specifically, the aluminum nitride powder of the present embodiment is preferably · A preparation step of preparing raw material powder, and · An introduction step of introducing the raw material powder into a firing furnace, and · A nitriding step of firing the raw material powder in a nitrogen atmosphere to obtain aluminum nitride powder, and · A recovery step of recovering the aluminum nitride powder from the firing furnace, and It can be manufactured through. Also, when manufacturing the aluminum nitride powder, there may be additional steps other than these.

[0037] <Preparation Process> In the preparation process of this embodiment, raw material powder is prepared. From the viewpoint of further improving thermal conductivity, the raw material powder of this embodiment preferably contains one or two selected from the group consisting of metallic aluminum and α-alumina, and more preferably contains metallic aluminum. When the raw material powder of this embodiment contains α-alumina, it preferably further contains carbon black.

[0038] When the raw material powder of this embodiment contains metallic aluminum, from the viewpoint of further improving thermal conductivity, when the total amount of the raw material powder is 100% by mass, the content of metallic aluminum in the raw material powder is preferably 95% by mass or more and 100% by mass or less, and more preferably 99% by mass or more and 100% by mass or less.

[0039] When the raw material powder of this embodiment contains α-alumina, from the viewpoint of further improving thermal conductivity, when the total amount of the raw material powder is 100% by mass, the content of α-alumina in the raw material powder is preferably 50% by mass or more and 65% by mass or less, and more preferably 55% by mass or more and 60% by mass or less. By setting the content of α-alumina in the raw material powder within the above range, the thermal conductivity of the obtained aluminum nitride powder can be further improved.

[0040] When the raw material powder of this embodiment contains metallic aluminum, from the viewpoint of further improving production safety, the raw material powder preferably contains atomized powder of metallic aluminum.

[0041] When the raw material powder of this embodiment contains metallic aluminum, from the viewpoint of further improving the balance between thermal conductivity and production safety, the average particle diameter of the raw material powder is preferably 17 μm or more and 23 μm or less, and more preferably 19 μm or more and 21 μm or less. By setting the average particle diameter of the raw material powder to be equal to or less than the above upper limit value, the thermal conductivity of the obtained aluminum nitride powder can be further improved.

[0042] When the raw material powder of the present embodiment contains metallic aluminum, from the viewpoint of further improving the thermal conductivity, when the total amount of the raw material powder is 100% by mass, the oxygen amount of the raw material powder is preferably 0.10% by mass or more and 0.25% by mass or less, more preferably 0.20% by mass or more and 0.25% by mass or less. By setting the oxygen amount of the raw material powder to be equal to or less than the above upper limit value, the thermal conductivity of the obtained aluminum nitride powder can be further improved.

[0043] When the raw material powder of the present embodiment contains α-alumina, the average particle diameter of the raw material powder is preferably 0.1 μm or more and 1.5 μm or less, more preferably 0.5 μm or more and 1.0 μm or less, and the specific surface area of the raw material powder is preferably 2 m 2 / g or more and 8 m 2 / g or less, more preferably 4 m 2 / g or more and 6 m 2 / g or less.

[0044] In the preparation step of the present embodiment, when the raw material powder contains α-alumina and carbon black, it is preferable to mix the α-alumina and the carbon black. Examples of the mixing method include dry mixing using a known device such as a blender or a mixer, and dry mixing using a known dry grinder.

[0045] <Introduction step> In the introduction step of the present embodiment, the raw material powder is introduced into a firing furnace. When the raw material powder of the present embodiment contains metallic aluminum, the raw material powder is preferably introduced into the firing furnace by being sprayed from a nozzle together with nitrogen gas. The spraying speed of the raw material powder and the nitrogen gas into the firing furnace is preferably 12 m / s or more and 18 m / s or less, more preferably 14 m / s or more and 16 m / s or less. By setting the spraying speed of the raw material powder and the nitrogen gas into the firing furnace within the above range, the thermal conductivity of the obtained aluminum nitride powder can be further improved.

[0046] When the raw material powder of this embodiment contains metallic aluminum, the mass of the raw material powder introduced into the firing furnace per unit time is preferably 12 kg or more and 18 kg or less, more preferably 14 kg or more and 16 kg or less, from the viewpoint of further improving thermal conductivity.

[0047] When the raw material powder of this embodiment contains metallic aluminum, the volume of nitrogen gas introduced into the firing furnace per unit time is preferably 15 m 3 from the viewpoint of further improving thermal conductivity. 3 More than 25m 3 Less than or equal to 18m, preferably 3 More than 22m 3 The following is the result.

[0048] <Nitriding process> In the nitriding step of this embodiment, the raw material powder is sintered in a nitrogen atmosphere to obtain aluminum nitride powder. In the nitriding step of this embodiment, the raw material powder is preferably sintered in an atmosphere in which nitrogen gas flows through a sintering furnace.

[0049] The firing temperature in the nitriding step of this embodiment is preferably 1500° C. or higher and 2000° C. or lower, more preferably 1900° C. or higher and 2000° C. or lower, from the viewpoint of further improving thermal conductivity. By setting the firing temperature in the nitriding step within the above range, the thermal conductivity of the resulting aluminum nitride powder can be further improved.

[0050] The purity of the nitrogen gas used in the nitriding step of this embodiment is preferably 99% by volume or more and 100% by volume or less, more preferably 99.9% by volume or more and 100% by volume or less, from the viewpoint of further improving thermal conductivity.

[0051] When the raw material powder of this embodiment contains metallic aluminum, the inner diameter of the firing furnace used in the nitriding step is preferably 350 mm or more and 450 mm or less, more preferably 380 mm or more and 420 mm or less, from the viewpoint of further improving the balance between thermal conductivity and productivity.

[0052] When the raw material powder of the present embodiment contains α-aluminum oxide, after the nitriding step of the present embodiment, it is preferable to perform an oxidation treatment in an air atmosphere under the conditions of 650°C or higher and 750°C or lower for 10 hours or longer and 14 hours or shorter.

[0053] <Recovery step> In the recovery step of the present embodiment, aluminum nitride powder is recovered from the firing furnace. When the raw material powder of the present embodiment contains metallic aluminum, the recovery step is preferably performed by sucking the produced aluminum nitride powder from the bottom of the firing furnace by a blower and collecting it with a bag filter.

[0054] <Aluminum nitride sintered body> The aluminum nitride sintered body of the present embodiment contains the aluminum nitride powder of the present embodiment. Since the aluminum nitride powder of the present embodiment has improved thermal conductivity, the aluminum nitride sintered body of the present embodiment also has improved thermal conductivity and can be suitably used for circuit boards and bonding substrates.

[0055] <Bonding substrate> The bonding substrate of the present embodiment includes the aluminum nitride sintered body of the present embodiment and a metal plate. Hereinafter, the bonding substrate of the present embodiment will be described with reference to FIG. 1, which is a perspective view schematically showing an example of the structure of the bonding substrate of the present embodiment.

[0056] The bonding substrate 200 includes a pair of metal plates 110 arranged to face each other and a plate-shaped aluminum nitride sintered body 100 between the pair of metal plates 110. Examples of the metal plate 110 include copper plates. The shapes and sizes of the aluminum nitride sintered body 100 and the metal plate 110 may be the same or different. The main surfaces of the metal plate 110 and the aluminum nitride sintered body 100 may be joined by, for example, a brazing material.

[0057] The bonding substrate 200 can sufficiently suppress the intrusion of foreign matter between the metal plate 110 and the aluminum nitride sintered body 100. Further, since the aluminum nitride sintered body 100 has improved thermal conductivity, the bonding substrate 200 is excellent in thermal conductivity.

[0058] One of the pair of metal plates 110 of the bonding substrate 200 may be used as a heat dissipation material, and the other may be processed into a conductor portion. The conductor portion may be formed by etching the metal plate 110 using a resist. Thereby, a circuit board excellent in thermal conductivity and capable of sufficiently suppressing leakage current and the like can be formed.

[0059] <Circuit board> The circuit board of the present embodiment includes the aluminum nitride sintered body of the present embodiment and a conductor portion. Hereinafter, the circuit board of the present embodiment will be described with reference to FIG. 2, which is a perspective view schematically showing an example of the structure of the circuit board of the present embodiment.

[0060] The circuit board 300 includes a plate-shaped aluminum nitride sintered body 100, a conductor portion 20 on one main surface 100A, and a metal plate 110 on the other main surface. The conductor portion 20 and the main surface 100A of the aluminum nitride sintered body 100 may be joined by, for example, a brazing material. When the circuit board 300 is used in a product such as a power module, the conductor portion 20 may constitute a part of the circuit, and the metal plate 110 may function as a heat dissipation material. Further, the circuit board 300 may have cooling fins instead of the metal plate 110.

[0061] The circuit board 300 can sufficiently suppress the intrusion of foreign matter between the conductor portion 20 and the metal plate 110 and the aluminum nitride sintered body 100. Further, since the aluminum nitride sintered body 100 has improved thermal conductivity, the circuit board 300 is excellent in thermal conductivity.

[0062] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various other configurations may be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. For example, the shapes and structures of the bonded substrate and the circuit board of this embodiment are not limited to those shown in Figures 1 and 2. For example, the circuit board may have conductors attached to both main surfaces of the aluminum nitride sintered body 100. Instead of forming the conductors 20 by etching the metal plate 110, the conductors 20 may be formed by spraying metal powder and then heat treating the metal powder. [Example]

[0063] The embodiments of the present invention will be described in detail based on examples, but the present invention is not limited to only the examples.

[0064] Example 1 A nozzle was used to feed 15 kg of metallic aluminum powder (atomized powder, average particle size 19.8 μm, oxygen content 0.25 mass%) per hour and 20.9 m of powder per hour into a 1820°C boron nitride furnace with an inner diameter of 400 mm and a total length of 3000 mm. 3 Normal nitrogen gas was sprayed at a speed of 15 m / s. The temperature inside the furnace during the reaction was maintained at 1950°C due to the heat of the nitriding reaction. The produced aluminum nitride powder was sucked from the bottom of the furnace with a blower and collected with a bag filter, yielding the aluminum nitride powder of Example 1.

[0065] Example 2 α-alumina (average particle size 0.8 μm, specific surface area 5.0 m 2 / g) 200 kg and carbon black (specific surface area 110 m 2 150 kg of aluminum nitride powder (150 kg of aluminum nitride powder / g) was mixed for 0.5 hours in a mixer equipped with a stirring blade. The resulting mixture was mixed for 2 hours in a batch-type rotary ball mill, and then nitrided in a nitrogen atmosphere at a firing temperature of 1600°C for 10 hours, followed by oxidation treatment in an air atmosphere at 700°C for 12 hours, to obtain 140 kg of aluminum nitride powder of Example 2.

[0066] <Raman Spectroscopy> Using a Raman spectroscopic analyzer (Raman microscope XploRA, manufactured by Horiba, Ltd.), the Raman spectroscopic spectrum of the aluminum nitride powder of each example was measured under the conditions of a laser wavelength of 532 nm, an objective lens magnification of 20x, a grating of 300 Gr / mm, a slit width of 50 μm, an exposure time of 1 second, and 10 exposures.

[0067] <Peak intensity> From the obtained Raman spectrum, the wave number was 150 cm -1 More than 350cm -1 The following range (A), 800 cm -1 More than 1000cm -1 The following range (B), 1250 cm -1 More than 1450cm -1 The following range (C), 1500 cm -1 More than 1700cm -1 The following ranges (D) and 500 cm -1 More than 750cm -1 The maximum peaks of scattering intensity present in each of the following ranges (X) were identified, and the peak positions (wave numbers) and peak intensities of the maximum peaks were measured. Then, the peak intensity of the maximum peak in the range (A) is I A , the peak intensity of the maximum peak in range (B) is I B , the peak intensity of the maximum peak in the range (C) is I C , the peak intensity of the maximum peak in the range (D) is I D , the peak intensity of the maximum peak in the range (X) is I X When I A / I X , I B / I X , I C / I X and I D / I X The values of were calculated, and the results are shown in Table 1. In addition, if the scattering intensity in range (C) or range (D) is low overall and the maximum peak cannot be identified, the peak position and IC / I X , I D / I X The value of is not stated.

[0068] <Particle size> Using a particle size distribution analyzer (MT3000II manufactured by Nikkiso Co., Ltd.), the volume frequency particle size distribution of the aluminum nitride powder of each example was measured by the laser diffraction scattering method in accordance with JIS R1629:1997. From the obtained volume frequency particle size distribution, the median diameter D 50 , the particle diameter D at which the cumulative value reaches 10% 10 , the particle diameter D at which the cumulative value reaches 90% 90 and (D 90 -D 10 ) / D 50 The results are shown in Table 1.

[0069] <Specific surface area> The specific surface area of the aluminum nitride powder of each example was measured using a specific surface area measuring device (MONOSORB, manufactured by Yuasa Ionics Co., Ltd.) by the BET single-point method in accordance with ISO 9277. The results are shown in Table 1.

[0070] <Amount of oxygen> The oxygen content (mass %) of the aluminum nitride powder of each example was measured using an oxygen / nitrogen simultaneous analyzer (EMGA920, manufactured by Horiba, Ltd.) The results are shown in Table 1.

[0071] <Thermal conductivity> For each example of aluminum nitride powder, 100 parts by weight of aluminum nitride powder, 4 parts by weight of yttrium oxide powder, 3 parts by weight of aluminum oxide powder, 6 parts by weight of a cellulose ether binder, 5 parts by weight of glycerin, and 10 parts by weight of ion-exchanged water were mixed to obtain a molding material. The molding material was then formed into a sheet, degreased by heating in air at 570°C for 5 hours, and then heated under a nitrogen gas atmosphere at atmospheric pressure and 1800°C for 4 hours to obtain an aluminum nitride sintered body. The thermal conductivity of the aluminum nitride sintered body was then measured at 23°C using a laser flash method in accordance with JIS R1611:2010. The results are shown in Table 1.

[0072]

Table 1

Explanation of Symbols

[0073] 20 Conductor part 100 Aluminum nitride sintered body 110 Metal plate 200 Bonding substrate 300 Circuit board

Claims

1. Aluminum nitride powder containing aluminum nitride particles, In the Raman spectrum of the aluminum nitride powder measured under the following conditions, the wavenumber is 150 cm －１ or more and 350 cm －１ or less in the range (A) and 800 cm －１ or more and 1000 cm －１ or less in the range (B), respectively, and the aluminum nitride powder having peaks in these ranges. (Condition) Laser wavelength: 532 nm Objective lens magnification: 20 times Gratting: 300 Gr / mm Slit width: 50 μm Exposure time: 1 second Number of exposures: 10 times

2. In the Raman spectrum, the peak intensity I of the maximum peak in the range (X) where the wave number is 500 cm －１ or more and 750 cm －１ or less, with respect to I Ｘ where the wave number is 1250 cm －１ or more and 1450 cm －１ or less in the range (C), the ratio I Ｃ / I Ｃ / I Ｘ is 0.020 or less. The aluminum nitride powder according to claim 1.

3. The aluminum nitride powder according to claim 2, having no peak in the range (C) in the Raman spectrum.

4. In the Raman spectrum, the peak intensity I of the maximum peak in the range (X) where the wave number is 500 cm －１ or more and 750 cm －１ or less, with respect to I Ｘ of the peak intensity of the maximum peak in the range (D) where the wave number is 1500 cm －１ or more and 1700 cm －１ or less, the ratio I Ｄ / I Ｄ / I Ｘ is 0.020 or less. The aluminum nitride powder according to any one of claims 1 to 3.

5. The aluminum nitride powder according to claim 4, having no peak in the range (D) in the Raman spectrum.

6. In the Raman spectrum, the peak intensity I of the maximum peak in the range (X) where the wave number is 500 cm －１ or more and 750 cm －１ or less, with respect to the peak intensity I Ｘ of the maximum peak in the range (A), the ratio I Ａ / I Ａ is 0.020 or more and 0.200 or less. The aluminum nitride powder according to any one of claims 1 to 3 Ｘ ​

7. In the Raman spectrum, the wave number is 500 cm －１ More than 750cm －１ The peak intensity I of the maximum peak in the following range (X) Ｘ The peak intensity I of the maximum peak in the range (B) Ｂ Ratio I Ｂ / I Ｘ The aluminum nitride powder according to any one of claims 1 to 3, wherein is 0.030 or more and 0.400 or less.

8. In the Raman spectrum, the aluminum nitride powder according to any one of claims 1 to 3 further has two or more peaks in a range (X) where the wave number is 500 cm －１ or more and 750 cm －１ or less.

9. The volume-based median diameter D of the aluminum nitride powder by the laser diffraction scattering method ５０ is 0.50 μm or more and 5.00 μm or less, and the aluminum nitride powder according to any one of claims 1 to 3.

10. In the volume frequency particle size distribution of the aluminum nitride powder by the laser diffraction scattering method, the particle diameter D at which the cumulative value is 10% １０ , the particle diameter D at which the cumulative value is 90% ９０ , and the median diameter D ５０ , for (D ９０ - D １０ ), the value of / D ５０ is 3.00 or less. The aluminum nitride powder according to any one of claims 1 to 3.

11. The specific surface area of the aluminum nitride powder measured by the BET single-point method in accordance with ISO 9277 is 1.00 m ２ / g or more and 5.00 m ２ / g or less. The aluminum nitride powder according to any one of claims 1 to 3.

12. The aluminum nitride powder according to any one of claims 1 to 3, wherein the amount of oxygen measured using an oxygen / nitrogen simultaneous analyzer in the aluminum nitride powder is 0.50% by mass or more and 0.90% by mass or less.

13. The aluminum nitride powder according to any one of claims 1 to 3, containing hexagonal aluminum nitride primary particles.

14. The aluminum nitride powder according to any one of claims 1 to 3, having a thermal conductivity of 120 W / (m·K) or more by the following method. (Method) 100 parts by mass of the aluminum nitride powder, 4 parts by mass of yttrium oxide powder, 3 parts by mass of aluminum oxide powder, 6 parts by mass of a cellulose ether binder, 5 parts by mass of glycerin, and 10 parts by mass of ion-exchanged water are mixed to obtain a molding material. Next, the molding material is formed into a sheet shape, heated at 570 °C for 5 hours in air for debinding, and then heated at 1800 °C for 4 hours under atmospheric pressure in a nitrogen gas atmosphere to obtain an aluminum nitride sintered body. Then, for the aluminum nitride sintered body, in accordance with JIS R1611:2010, the thermal conductivity is measured by the laser flash method under the condition of 23 °C.

15. An aluminum nitride sintered body containing the aluminum nitride powder according to any one of claims 1 to 3.

16. A circuit board including the aluminum nitride sintered body according to claim 15 and a conductor portion.

17. A bonding substrate including the aluminum nitride sintered body according to claim 15 and a metal plate.

Images