JP7080422B1 - Aluminum nitride sintered body and its manufacturing method, circuit board, and bonded substrate - Google Patents

Abstract

Provided is an aluminum nitride sintered body containing aluminum nitride as a main component, zirconium nitride as a subcomponent, and an oxide having yttrium and aluminum as constituent elements, and the oxide contains Y2O3 and Al2O3. Provided is a circuit board 300 including an aluminum nitride sintered body 100 and a conductor portion 20 attached to the aluminum nitride sintered body 100.

Description

The present disclosure relates to aluminum nitride sintered bodies, circuit boards, and bonded substrates.

In recent years, power modules for high power control have been used in industrial equipment such as motors and products such as electric vehicles. In such a power module, a circuit board or the like provided with a ceramic plate is used in order to efficiently diffuse the heat generated from the semiconductor element and suppress the leakage current. The ceramic sintered body used for such a ceramic plate is usually manufactured by molding a ceramic raw material powder into a predetermined shape to form a ceramic molded body, and then sintering the ceramic molded body.

As the ceramic sintered body, those composed of nitrides, carbides, borides, silices and the like are known. Of these, 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 enhance the suitability for these applications, in Patent Document 1, an aluminum nitride sintered body is used as a sintering aid by using a nitride selected from the group of Zr and Ti in an amount of 3 to 20 parts by mass in terms of oxide. A technique for increasing the thermal conductivity and mechanical strength of Zirconium has been proposed.

Japanese Unexamined Patent Publication No. 2018-184316

Electronic components such as power modules are being further improved in performance, and along with this, it is expected that the level of performance requirements for various products used in electronic components will become higher and higher. It is considered that adding zirconium nitride while reducing the oxygen content in the aluminum nitride sintered body as in Patent Document 1 is effective in improving the thermal conductivity. However, as in Patent Document 1, it was found that when the amount of YAM (2Y ₂ O ₃ , Al ₂ O ₃ ) in the auxiliary agent phase increases, the fracture toughness value among the mechanical properties decreases.

The present disclosure provides an aluminum nitride sintered body having a high fracture toughness value. Further, by providing such an aluminum nitride sintered body, a circuit board and a bonded substrate having excellent reliability are provided.

The aluminum nitride sintered body according to one aspect of the present disclosure contains aluminum nitride as a main component, zirconium nitride as a subcomponent, and an oxide having yttrium and aluminum as constituent elements, and the oxide is _Y2 . Contains O ₃ , Al ₂ and O ₃ .

The aluminum nitride sintered body contains an _oxide containing _Y2O3 and _Al2O3 as an auxiliary component _together with zirconium nitride. Aluminum nitride contained as a main component has high thermal conductivity. By containing the above-mentioned sub-component in addition to this main component, the fracture toughness value can be increased without significantly impairing the thermal conductivity. Such an aluminum nitride sintered body can improve the reliability of products in which the aluminum nitride sintered body is used, such as a power module.

The oxide may contain 3Y ₂ O _{3.5Al 2} O ₃ . This makes it possible to improve the electrical insulation.

_{The content} of _Y2O3 / _{Al2O3 may} be _{higher than} the content of _3Y2O3.5Al2O3 . Thereby, the fracture toughness value can be further increased.

The circuit board according to one aspect of the present disclosure includes an aluminum nitride sintered body and a conductor portion attached to the aluminum nitride sintered body. This circuit board comprises the aluminum nitride sintered body described above having a high fracture toughness value. Therefore, this circuit board has excellent reliability. Further, when used in a product such as a power module, the reliability of the product can be improved.

The bonding substrate according to one aspect of the present disclosure includes any of the above-mentioned aluminum nitride sintered bodies and a metal plate attached to the aluminum nitride sintered body. This bonded substrate comprises the aluminum nitride sintered body described above having a high fracture toughness value. Therefore, this bonded substrate has excellent reliability. Further, when used in a product such as a power module, the reliability of the product can be improved.

According to the present disclosure, it is possible to provide an aluminum nitride sintered body having a high fracture toughness value. Further, by providing such an aluminum nitride sintered body, it is possible to provide a circuit board and a bonded substrate having excellent reliability.

FIG. 1 is a perspective view showing a bonding substrate according to an embodiment. FIG. 2 is a perspective view of a circuit board according to an embodiment.

Hereinafter, an embodiment 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. The dimensional ratio of each element is not limited to the ratio shown in the figure.

The aluminum nitride sintered body of the present embodiment contains aluminum nitride as a main component, zirconium nitride as a subcomponent, and an oxide having yttrium and aluminum as constituent elements _, and the oxide is _Y2O3 . -Contains Al ₂ O ₃ . The main component in the present disclosure means the component having the highest content among the components contained in the ceramic sintered body. Components other than the main component are referred to as sub-components. The sub-component is a component different from the main component and may be dispersed in the main component. For example, the sub-component may be contained in the grain boundaries of the aluminum nitride particles as the main component.

The content of the main component (aluminum nitride) in the aluminum nitride sintered body may be 80% by mass or more, 85% by mass or more, and 90% by mass or more from the viewpoint of increasing thermal conductivity. You may. The content of the main component (aluminum nitride) in the aluminum nitride sintered body may be 97% by mass or less, 95% by mass or less, and 93, from the viewpoint of obtaining a sufficiently dense aluminum nitride sintered body. It may be mass% or less. The content of each component of the aluminum nitride sintered body can be determined by, for example, X-ray diffraction. For X-ray diffraction, for example, MiniFlex (device name) manufactured by Rigaku Co., Ltd. can be used.

The content of zirconium nitride in the aluminum nitride sintered body may be 3% by mass or more, 4% by mass or more, or 5% by mass or more. This makes it possible to increase the strength. From the same viewpoint, the content of zirconium nitride with respect to the total subcomponent may be 10% by mass or more, 20% by mass or more, or 30% by mass or more. The content of zirconium nitride in the aluminum nitride sintered body may be 10% by mass or less, or 9% by mass or less, from the viewpoint of maintaining thermal conductivity. From the same viewpoint, the content of zirconium nitride with respect to the total subcomponent may be 70% by mass or less, 60% by mass or less, or 55% by mass or less.

The content of the oxide having yttrium and aluminum as constituent elements in the aluminum nitride sintered body may be 0.5% by mass or more from the viewpoint of sufficiently densifying the aluminum nitride sintered body, and is 1% by mass. It may be the above, and may be 2% by mass or more. The content of the oxide having yttrium and aluminum as constituent elements in the aluminum nitride sintered body may be 8% by mass or less, 7% by mass or less, and 5 from the viewpoint of increasing thermal conductivity. It may be mass% or less. The content and composition of these oxides can be determined, for example, by removing the main component from the aluminum nitride sintered body by a hydrolysis reaction using an aqueous sodium hydroxide solution and then performing X-ray diffraction of the residue. can. For X-ray diffraction, for example, MiniFlex (device name) manufactured by Rigaku Co., Ltd. can be used.

_Oxides having _yttrium and aluminum as constituent elements contain _Y2O3 and _Al2O3 . Y ₂ O ₃ · Al ₂ O ₃ is a kind of Y ₂ O ₃ − Al ₂ O ₃ system compound, and is a component also called YAP. Hereinafter, it may be referred to as "YAP" in the present disclosure. The content of YAP with respect to the entire oxide having yttrium and aluminum as constituent elements may be 30% by mass or more, 40% by mass or more, and may be 40% by mass or more, from the viewpoint of sufficiently densifying the aluminum nitride sintered body. It may be 50% by mass or more. On the other hand, from the viewpoint of increasing the electrical insulation of the aluminum nitride sintered body, the content of YAP with respect to the entire oxide having yttrium and aluminum as constituent elements may be 80% by mass or less, and may be 75% by mass or less. It may be 70% by mass or less. An example of the YAP content with respect to the entire oxide having yttrium and aluminum as constituent elements is 30 to 80% by mass.

The oxide having yttrium and aluminum as constituent elements may contain 3Y ₂ O _3.5 Al ₂ O ₃ in addition to Y ₂ O ₃・ Al ₂ O ₃ . _{3Y 2O 3.5Al 2O 3} is also a kind of _{Y2O3 - Al2O3} system compound and is a component also called YAG. Hereinafter, it may be referred to as "YAG" in the present disclosure. The content of YAG with respect to the entire oxide having yttrium and aluminum as constituent elements may be 5% by mass or more, 10% by mass or more, and 15% by mass or more from the viewpoint of increasing the electrical insulating property. There may be. The content of YAG with respect to the entire oxide having yttrium and aluminum as constituent elements may be 50% by mass or less, 40% by mass or less, from the viewpoint of sufficiently densifying the aluminum nitride sintered body. It may be 35% by mass or less. An example of the content of YAG with respect to the whole oxide having yttrium and aluminum as constituent elements is 5 to 50% by mass.

The content of YAP may be higher than the content of YAG. Thereby, the fracture toughness value of the aluminum nitride sintered body can be further increased. From the same viewpoint, the mass ratio of YAP to YAG is 1.1 or more, may be 1.5 or more, and may be 2 or more. The mass ratio can be adjusted by changing the composition (type and blending ratio) of the sintering aid used as a raw material and the firing conditions. For example, the mass ratio can be increased by increasing the blending ratio of Y ₂ O ₃ to Al ₂ O ₃ used as a sintering aid. The mass ratio of YAP to YAG may be, for example, 10 or less.

The aluminum nitride sintered body may contain an oxide other than YAP and YAG as an oxide having yttrium and aluminum as constituent elements. However, from the viewpoint of maintaining a high fracture toughness value, it is preferable that the content of 2Y ₂ O ₃ · Al ₂ O ₃ which is a kind of Y ₂ O ₃ − Al ₂ O ₃ system compound is low. Hereinafter, in the present disclosure, 2Y ₂ O ₃ and Al ₂ O ₃ may be referred to as “YAM”. The content of YAM with respect to the entire oxide may be 10% by mass or less, 5% by mass or less, and 1% by mass or less from the viewpoint of sufficiently increasing the fracture toughness value of the aluminum nitride sintered body. There may be. The aluminum nitride sintered body may be substantially free of YAM. For example, it may be less than 0.1% by mass.

The aluminum nitride sintered body may contain zirconium nitride as an auxiliary component and an oxide having yttrium and aluminum as constituent elements. Examples of such subcomponents include aluminum oxide, yttrium oxide and the like. However, from the viewpoint of suppressing the decrease in thermal conductivity, it is preferable that the content of aluminum oxide is low. The content of aluminum oxide (Al ₂ O ₃ ) in the aluminum nitride sintered body may be 1% by mass or less, 0.5% by mass or less, or 0.1% by mass or less. ..

The oxygen content in the aluminum nitride sintered body may be 0.3 to 3% by mass, and may be 0.5 to 2% by mass. Oxygen may be contained in the oxide contained as a subcomponent. By containing oxygen in the above range, the density and thermal conductivity of the aluminum nitride sintered body can be sufficiently increased. The oxygen content in the aluminum nitride sintered body can be determined by a commercially available oxygen / nitrogen analyzer.

The outer shape of the aluminum nitride sintered body is not particularly limited, and may be, for example, a plate shape. This makes it possible to smoothly join with other members. The thermal conductivity of the aluminum nitride sintered body conforms to JIS R1611 and can be measured by a laser flash method. The measurement sample can be processed into a sheet having a thickness of 1.0 mm for measurement. The shape of the sheet may be a rectangular parallelepiped shape of length × width × thickness = 50 mm × 50 mm × 1.0 mm. As the measuring device, for example, LF / TCM-8510B (trade name) manufactured by Rigaku Corporation is used. The measurement temperature may be 23 ± 1 ° C.

The thermal conductivity of the aluminum nitride sintered body may be 100 W / m · K or more, 120 W / m · K or more, or 140 W / m · K or more. Such an aluminum nitride sintered body is suitable as a heat sink material for, for example, a power module or the like. However, its use is not limited to this.

The fracture toughness value ( _KIC ) of the aluminum nitride sintered body may be 3.1 MPa · m ^1/2 or more, 3.3 MPa · m ^1/2 or more, and 3.5 MPa · m ^{1 /} It may be ² or more. The fracture toughness value (KIC) in the present disclosure is a value measured by the _SEBP method and is measured in accordance with JIS R1607: 2015. The upper limit of the fracture toughness value ( _KIC ) of the aluminum nitride sintered body may be, for example, 6 MPa · m ^1/2 from the viewpoint of ease of manufacture.

The density of the aluminum nitride sintered body may be 3.0 g / cm ³ or more and may be 3.1 g / cm ³ or more from the viewpoint of sufficiently increasing the thermal conductivity. The density can be adjusted by changing the blending ratio of the sintering aid used as a raw material, molding conditions and firing conditions.

An example of a method for manufacturing an aluminum nitride sintered body will be described below. First, prepare the raw materials. As the raw material, for example, aluminum nitride powder, zirconium nitride powder, sintering aid, additives and the like can be used. Examples of the additive include a binder, a plasticizer, a dispersion medium, a mold release agent and the like. Examples of the binder include a methylcellulose-based binder having a plasticity or a surface-active effect, and an acrylic acid ester-based binder having an excellent thermal decomposition property. Examples of the plasticizer include glycerin. Examples of the dispersion medium include ion-exchanged water and ethanol. The aluminum nitride powder is not particularly limited, and is an aluminum nitride powder produced by a known method such as a direct nitriding method in which metallic aluminum is nitrided in a nitrogen atmosphere and a reduced nitriding method in which aluminum oxide is reduced with carbon. Can be used. The zirconium nitride powder is also not particularly limited, and one produced by a known production method can be used.

As the sintering aid, one that forms a particulate oxide having yttrium and aluminum is used. For example, aluminum oxide and yttrium oxide are used. These form a liquid phase and promote sintering. Thereby, the aluminum nitride sintered body can be sufficiently densified. The composition of the oxide in the aluminum nitride sintered body may be adjusted by changing the blending ratio of both. For example, the mass ratio of aluminum oxide to yttrium oxide may be 0.5 to 2 or 0.8 to 1.5. This promotes the production of YAP and can sufficiently increase the fracture toughness value. In addition, the thermal conductivity can be sufficiently increased.

Aluminum nitride powder, zirconium nitride powder, sintering aid and additives are mixed and mixed to obtain a molding raw material. The molding raw material is molded into a sheet, for example, by a known method such as a doctor blade method. The obtained molded body may be degreased. The degreasing method is not particularly limited, and for example, the molded product 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-mentioned molded product. The firing is carried out by raising the temperature to 1760 to 1840 ° C. in an atmosphere of an inert gas. The holding time at 1760 to 1840 ° C. is, for example, 1 to 6 hours. If the firing temperature is too low or the holding time is too short, the formation of YAG is promoted and the mass ratio of YAP to YAG tends to be small. On the other hand, if the firing temperature is too high or the holding time is too long, abnormal grain growth or the like is likely to occur, and the variation in fracture toughness value tends to be large. Baking may be carried out under atmospheric pressure.

The aluminum nitride sintered body obtained by the above-mentioned production method may be processed into a desired shape, if necessary. A conductor portion or a metal plate may be attached to the aluminum nitride plate to form a circuit board or a bonded board. The bonded substrate may be manufactured by joining, for example, the main surface of an aluminum nitride plate and the main surface of a metal plate such as a copper plate using a brazing material. The bonded substrate may have a laminated structure having a pair of metal plates and an aluminum nitride sintered body between them.

The circuit board may be manufactured by removing a part of the metal plate of the bonded substrate by etching or the like to form a conductor portion to be a circuit. In the circuit board, the conductor portion may be attached to each of the pair of main surfaces of the plate-shaped aluminum nitride sintered body, or the conductor portion may be attached to only one main surface. When the conductor portion is attached only to one main surface, a metal plate may be attached to the other main surface, or a cooling fin serving as a heat sink may be attached to the other main surface.

FIG. 1 is a perspective view of a bonding substrate according to an embodiment. The bonding substrate 200 includes a pair of metal plates 110 arranged so as 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 a copper plate. The shape and size 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 to each other by, for example, a brazing material. In the bonding substrate 200, one of the pair of metal plates 110 may be used as a heat radiating material, and the other may be processed into a conductor portion. The conductor portion may be formed by etching the metal plate 110 with a resist. This makes it possible to form a circuit board having excellent reliability.

FIG. 2 is a perspective view of a circuit board according to an embodiment. 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 constitutes a part of an electric circuit in a product such as a power module. 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 form a part of the circuit, and the metal plate 110 may function as a heat radiating material. Further, the circuit board 300 may have cooling fins instead of the metal plate 110. Since the circuit board 300 includes the aluminum nitride sintered body 100 having a high fracture toughness value, the circuit board 300 is excellent in reliability. Therefore, it can be suitably used for various products such as power modules.

Although some embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments. For example, the shapes and structures of the aluminum nitride sintered body, the bonded substrate and the circuit board of the present disclosure are not limited to those of FIGS. 1 and 2. For example, the circuit board may have conductor portions attached to both main surfaces of the aluminum nitride sintered body 100. The conductor portion 20 may be formed by spraying a metal powder and heat-treating it instead of forming the metal plate 110 by etching.

Hereinafter, the contents of the present disclosure will be described in more detail with reference to Examples and Comparative Examples. However, the present disclosure is not limited to the following examples.

[Example 1]
(Manufacturing of aluminum nitride sintered body)
Aluminum nitride powder, zirconium nitride powder, yttrium oxide powder, and aluminum oxide powder are blended in a mass ratio of 90.5: 3.0: 3.5: 3.0 and mixed using a ball mill. A mixed powder was obtained. 6 parts by mass of cellulose ether binder (manufactured by Shinetsu Chemical Industry Co., Ltd., trade name: Metrose), 5 parts by mass of glycerin (manufactured by Kao Co., Ltd., trade name: Exepearl) and ion exchange with respect to 100 parts by mass of the mixed powder. 10 parts by mass of water was added and mixed for 1 minute using a Henchel mixer to obtain a molding raw material. This molding raw material was molded by the doctor blade method to prepare a sheet-shaped molded body (thickness: 1.4 mm).

The molded product was degreased by heating in air at 570 ° C. for 5 hours. Next, the degreased molded product was placed in a heating furnace and heated to 1800 ° C. in a nitrogen gas atmosphere (atmospheric pressure). After holding at 1800 ° C. for 4 hours, the sintered body was allowed to cool in a heating furnace. In this way, an aluminum nitride sintered body was produced.

(Composition analysis)
X-ray diffraction measurement was performed to analyze the composition of the aluminum nitride sintered body. For the analysis, MiniFlex (trade name) manufactured by Rigaku Co., Ltd. was used. In addition to aluminum nitride, which is the main component, zirconium nitride (ZrN) _, Y2O3 ・_{Al2O3 (} YAP) _, and _{3Y2O3.5Al2O3 (} YAG) _were detected as sub _- components. .. On the other hand, 2Y ₂ O ₃ and Al ₂ O ₃ (YAM) were not detected.

The aluminum nitride sintered body was immersed in a sodium hydroxide aqueous solution (NaOH concentration: 10%) at about 20 ° C. for 24 hours, and aluminum nitride as a main component was dissolved by a hydrolysis reaction. Using the above-mentioned X-ray diffraction measuring device, qualitative and quantitative analysis of residual zirconium nitride and auxiliary components including oxides having yttrium and aluminum as constituent elements was performed. The content of each sub-ingredient was as shown in Table 1. In Table 1, the content of the entire sub-components based on the aluminum nitride sintered body and each component based on the entire sub-components (total value of the components excluding the main component from the aluminum nitride sintered body) are shown. The content of is shown. Table 2 shows the contents of YAP, YAG, and YAM with respect to the entire oxide having yttrium and aluminum as constituent elements. The ratio of YAP to YAG is also shown.

(Measurement of oxygen content)
The oxygen content in the aluminum nitride sintered body was measured using an oxygen / nitrogen analyzer (trade name: EMGA-920) manufactured by HORIBA, Ltd. The measurement results are as shown in Table 1. The oxygen content is a value based on the entire aluminum nitride sintered body.

(Measurement of fracture toughness value)
The fracture toughness value ( _KIC ) of the aluminum nitride sintered body was measured. This fracture toughness value (KIC) is a value measured by the _SEBP method, conforms to JIS R1607: 2015, and is measured using a commercially available measuring device (manufactured by Instron, device name: universal testing machine 5582 type). did. The measurement results were evaluated according to the following criteria.
3.5MPa / m ^1/2 or more: A
More than 3.0 Pa / m ^1/2 and less than 3.5 MPa / m ^1/2 : B
3.0 Pa / m ^1/2 or less: C

(Measurement of thermal conductivity)
The aluminum nitride sintered body was processed to prepare a measurement sample having a rectangular parallelepiped shape of length × width × thickness = 50 mm × 50 mm × 1.0 mm. According to JIS R1611: 2011, the thermal conductivity of the above-mentioned measurement sample was measured by a laser flash method. As the measuring device, LF / TCM-8510B (trade name) manufactured by Rigaku Co., Ltd. was used. The measurement temperature was 23 ± 1 ° C.

[Example 2]
Aluminum nitride powder, zirconium nitride powder, yttrium oxide powder, and aluminum oxide powder are blended in a mass ratio of 90: 3.5: 3.5: 3.0, mixed using a ball mill, and mixed powder. Got Molding and firing were carried out in the same manner as in Example 1 except that this mixed powder was used to obtain an aluminum nitride sintered body. Each evaluation of the aluminum nitride sintered body thus obtained was carried out in the same procedure as in Example 1. The results are as shown in Tables 1 and 2.

[Example 3]
Aluminum nitride powder, zirconium nitride powder, yttrium oxide powder, and aluminum oxide powder are mixed at a mass ratio of 86.5: 7.0: 3.5: 3.0 and mixed using a ball mill. A mixed powder was obtained. Molding and firing were carried out in the same manner as in Example 1 except that this mixed powder was used to obtain an aluminum nitride sintered body. Each evaluation of the aluminum nitride sintered body thus obtained was carried out in the same procedure as in Example 1. The results are as shown in Tables 1 and 2.

[Example 4]
An aluminum nitride sintered body was obtained in the same manner as in Example 1 except that the holding time at 1800 ° C. in the heating furnace was set to 6 hours. Each evaluation of the aluminum nitride sintered body thus obtained was carried out in the same procedure as in Example 1. The results are as shown in Tables 1 and 2.

[Comparative Example 1]
Aluminum nitride powder, zirconium nitride powder, and yttrium oxide powder were blended in a mass ratio of 93.5: 3.5: 3.0 and mixed using a ball mill to obtain a mixed powder. Molding and firing were carried out in the same manner as in Example 1 except that this mixed powder was used to obtain an aluminum nitride sintered body. Each evaluation of the aluminum nitride sintered body thus obtained was carried out in the same procedure as in Example 1. The results are as shown in Tables 1 and 2.

[Comparative Example 2]
Aluminum nitride powder, yttrium oxide powder, and aluminum oxide powder were blended in a mass ratio of 93.5: 3.5: 3.0 and mixed using a ball mill to obtain a mixed powder. An aluminum nitride sintered body was obtained in the same manner as in Example 1 except that this mixed powder was used. Each evaluation of the aluminum nitride sintered body thus obtained was carried out in the same procedure as in Example 1. The results are as shown in Tables 1 and 2.

"-" In Table 1 indicates that it was not detected by X-ray diffraction. The thermal conductivity of the aluminum nitride sintered bodies of Examples 1, 2 and 4 containing ZrN and YAP exceeded 120 W / m · K. Further, the thermal conductivity of the aluminum nitride sintered body of Example 3 exceeded 100 W / m · K. As described above, it was confirmed that the aluminum nitride sintered bodies of Examples 1 to 4 have a high fracture toughness value while maintaining a high thermal conductivity. In Examples 1 to 4, aluminum oxide, yttrium oxide and YAM were not detected and were below the detection limit (<0.1% by mass). As described above, the content of each oxide in Table 2 was calculated on the assumption that the components below the detection limit were not contained in the aluminum nitride sintered body.

According to the present disclosure, an aluminum nitride sintered body having a high fracture toughness value is provided. Further, by providing such an aluminum nitride sintered body, a circuit board and a bonded substrate having excellent reliability are provided.

20 ... Conductor part, 100 ... Aluminum nitride sintered body, 110 ... Metal plate, 200 ... Bonded substrate, 300 ... Circuit board.

Claims (8)

Aluminum nitride as the main component,
It contains zirconium nitride as an accessory component and an oxide having yttrium and aluminum as constituent elements.
The content of the main component is 80 to 97% by mass with respect to the total of the main component and the sub-component.
For the entire oxide
The content of Y ₂ O ₃ and Al ₂ O ₃ is 40% by mass or more, and the content is 40% by mass or more.
The content of 3Y ₂ O 3.5Al ₂ O ₃ is 10% by mass or more _, and the content is 10% by mass or more.
An aluminum nitride sintered body having a content of 2Y ₂ O ₃ and Al ₂ O ₃ of 1% by mass or less. _The aluminum nitride sintered body according to claim 1 _{, wherein the} content of _Y2O3 / _Al2O3 is higher _than the content of _3Y2O3.5Al2O3 . Aluminum nitride as the main component,
It contains zirconium nitride as an accessory component and an oxide having yttrium and aluminum as constituent elements.
The content of the main component is 80 to 97% by mass with respect to the total of the main component and the sub-component.
The oxide contains Y 2 _{O 3} · _Al 2 _O 3 _and 3Y ₂ O 3.5 Al ₂ O ₃ and
An aluminum nitride sintered body in which the ratio of Y ₂ O _{3 and Al 2 O 3 to 3Y 2} O _3.5 Al ₂ O ₃ is 2 or more. The aluminum nitride sintered body according to any one of claims 1 to 3, wherein the content of the zirconium nitride with respect to the entire subcomponent is 10 to 70% by mass. The aluminum nitride sintered body according to any one of claims 1 to 4, wherein the content of the oxide with respect to the entire aluminum nitride sintered body is 2 to 8% by mass. A circuit board comprising the aluminum nitride sintered body according to any one of claims 1 to 5 and a conductor portion attached to the aluminum nitride sintered body. A bonded substrate comprising the aluminum nitride sintered body according to any one of claims 1 to 5 and a metal plate attached to the aluminum nitride sintered body. A step of molding a raw material containing aluminum nitride powder, zirconium nitride powder, and a sintering aid containing aluminum oxide and yttrium oxide to obtain a molded body, and the molded body at 1760 to 1840 ° C. for 1 to 6 hours. It has a process of firing and firing to obtain an aluminum nitride sintered body.
It contains aluminum nitride as a main component, zirconium nitride as a subcomponent, and an oxide having yttrium and aluminum as constituent elements.
The content of the main component is 80 to 97% by mass with respect to the total of the main component and the sub-component.
A method for producing an aluminum nitride sintered body, wherein the oxide contains Y ₂ O ₃ and Al ₂ O ₃ .

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