Alumina sintered body and wiring board

Abstract

To provide an alumina sintered body that can be sintered at a temperature at which low-loss electrodes can be used, while suppressing the amount of sintering aid added so as not to impair the properties of the base material. [Solution] In the alumina sintered body containing manganese (Mn), the manganese element is contained as a manganese compound with an average particle size of 1 micrometer (μm) or less.

Description

Technical Field

[0001] The present invention relates to an alumina sintered body and a wiring board.

Background Art

[0002] Products using a ceramic material fired after mixing a ceramic powder as a raw material with powders such as metal oxides and carbonates are known (see, for example, Patent Documents 1 and 2). The alumina multilayer wiring board described in Patent Document 2 is formed of a ceramic material sintered after mixing alumina fine powder having a particle size of 5 to 50 nm and an alkaline earth metal compound.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technologies described in Patent Documents 1 and 2, since the amount of the sintering aid added during mixing before firing is large, there is a risk that the mechanical strength, thermal conductivity characteristics, and electrical characteristics, which are the characteristics of the base material, may be impaired. On the other hand, by using nanoparticles as the sintering aid added to the mixed powder before sintering, it is expected that the base material particles can be covered even with a small amount of addition, and the sinterability can be improved. However, nanoparticles are very likely to aggregate and it is difficult to disperse them uniformly, and the cost is also high.

[0005] The present invention has been made to solve at least a part of the above-described problems, and an object thereof is to provide an alumina sintered body that suppresses the amount of the sintering aid added so as not to impair the characteristics of the base material and can be sintered at a temperature at which a low-loss electrode can be used.

Means for Solving the Problems

[0006] The present invention was made to solve at least some of the problems described above, and can be realized in the following forms.

[0007] (1) According to one embodiment of the present invention, an alumina sintered body containing the element manganese (Mn) is provided. In this alumina sintered body, the element manganese is contained as a manganese compound with an average particle size of 1 micrometer (μm) or less.

[0008] With this configuration, the manganese element is well dispersed within the alumina sintered body as manganese compounds with an average particle size of 1 μm or less, and functions as a sintering aid. Therefore, with this configuration, even if the amount of manganese compound contained in the material of the alumina sintered body is small, sintering during the manufacturing of the alumina sintered body is promoted. As a result, the firing temperature of the alumina sintered body with this configuration can be reduced.

[0009] (2) In the alumina sintered body of the above form, the manganese element content may be 5 wt% or less. With this configuration, the manganese element is dispersed within the alumina sintered body as small manganese compounds, so even if the manganese element content is as low as 5% or less, the sintering temperature of the alumina sintered body decreases.

[0010] (3) In the ceramic powder of the above form, when an AC electric field of 1 MHz is applied, the dielectric loss is 1.0 × 10 -4 The following is also acceptable. With this configuration, the dielectric loss when an AC electric field is applied is 1.0 × 10⁻⁶. -4 It can be made smaller as follows.

[0011] (4) In the ceramic powder of the above form, the insulation resistance is 1.0 × 10 14 It is acceptable if it is greater than Ω·cm. According to this configuration, the insulation resistance is 1.0 × 10⁻⁶ 14 It can achieve high insulation properties of Ω·cm or more.

[0012] (5) In the ceramic powder of the above form, the flexural strength may be 450 MPa or more, and the hardness may be 19 GPa or more. According to this configuration, the flexural strength can be increased to as high as 450 MPa, and the hardness can be increased to as high as 19 GPa.

[0013] (6) According to another aspect of the present invention, a wiring board is provided. This wiring board includes an insulating layer formed of the alumina sintered body of the above form, and an electrode containing at least one of copper (Cu), tungsten (W), and molybdenum (Mo). According to this configuration, the manganese element as a sintering aid is well dispersed as a manganese compound having an average particle diameter of 1 μm or less in the alumina sintered body. Therefore, according to this configuration, the wiring board can be sintered at a lower temperature.

[0014] Note that the present invention can be realized in various aspects. For example, it can be realized in the form of an alumina sintered body, a ceramic material, a sintered body, a wiring board, and a system including these, a manufacturing method of a ceramic material, a manufacturing method of a wiring board, and a system including these.

Brief Description of Drawings

[0015] [Figure 1] It is a schematic cross-sectional view of a wiring board as an embodiment of the present invention. [Figure 2] It is a flowchart of a method for manufacturing manganese-supported alumina raw material powder. [Figure 3] It is an explanatory diagram of the relationship between the sintering temperature and the shrinkage rate due to sintering. [Figure 4] It is a flowchart of a method for manufacturing the wiring board of the present embodiment. [Figure 5] It is an explanatory diagram of EDS of the ceramic powder of Example 1. [Figure 6] It is an explanatory diagram of EDS of the ceramic powder of Example 1. [Figure 7] It is an explanatory diagram of EDS of the ceramic powder of Comparative Example 1. [Figure 8]This is an explanatory diagram of the EDS of the ceramic powder in Comparative Example 1. [Figure 9] This is an explanatory diagram illustrating the characteristics of the wiring board and substrate used in Example 1. [Figure 10] This diagram illustrates the relative density of the alumina sintered bodies in Examples 1-7 and Comparative Examples 1 and 3. [Figure 11] This diagram illustrates the relationship between sintering temperature and shrinkage rate for Comparative Examples 3-5 using copper elements. [Figure 12] This is a flowchart of the method for producing alumina powder according to the second embodiment. [Modes for carrying out the invention]

[0016] <First Embodiment> Figure 1 is a schematic cross-sectional view of a wiring board 100 as one embodiment of the present invention. The wiring board 100 of this embodiment is used for circuit formation in electronic components, IC packages, sensor devices, and semiconductor manufacturing equipment. The wiring board 100 shown in Figure 1 comprises four substrates 10 that function as insulating layers, and three conductive layers (electrodes) 20 arranged inside each of the four substrates 10. Details of the manufacturing method of the wiring board 100 will be described later, but the wiring board 100 is manufactured by laminating the four substrates 10 and the three conductive layers 20. Note that there are not necessarily four insulating layers; there may be one or more layers.

[0017] The base material 10 is formed from an alumina sintered body containing manganese (Mn). The manganese contained in the base material 10 is present as manganese compounds with an average particle size of 1 micrometer (μm) or less. The manganese content in the base material 10 is 5 wt% or less.

[0018] Each of the three conductive layers 20 is formed by a plurality of conductive films 21. The plurality of conductive films 21 contained in one conductive layer 20 are processed into a predetermined wiring pattern by known wiring patterning techniques such as screen printing or laser trimming. The conductive films 21 contain copper (Cu) and at least one of tungsten (W) or molybdenum (Mo) (for example, containing Cu and W). The conductive films 21 may also contain platinum, nickel, titanium, iron, and chromium. The dashed line shown in Figure 1 represents the boundary line between the two laminated substrates 10. This boundary line may not be distinguishable in the cross-section of the wiring board 100.

[0019] Figure 2 is a flowchart of the manganese-supported alumina raw material powder. In the manufacturing flow shown in Figure 2, first, alumina powder as the base material, a binder, a solvent, and a manganese-containing complex are prepared (Step S1). The manganese-containing complex functions as a sintering aid. Next, the alumina powder other than the complex, the binder, and the solvent are combined and kneaded using a three-roller system (Step S2). Kneading before mixing in the complex suppresses the aggregation of alumina. Note that if the aggregation of the base material is minor, Step S2 can be omitted.

[0020] The complex is added to the kneaded mixture and kneaded further to obtain a paste (Step S3). Note that the process in Step S3 corresponds to the kneading process. To evaporate the solvent contained in the paste, it is dried at 120°C for 12 hours (Step S4). Next, a degreasing process is performed to degrease the powder, which is a mixture of dried alumina powder and the complex (Step S5). The degreasing process is carried out at 450°C for 5 hours, a temperature at which the binder and organometallic complex decompose. Through this process, manganese oxide nanoparticles, which act as auxiliary agents, precipitate on the surface of the alumina powder, which is the base material, and a ceramic powder is produced in which a thin film is supported on the surface of the base material.

[0021] The component ratios of the base material and the thin film supported on the surface of the base material were confirmed by chemical analysis and X-ray fluorescence analysis of the manufactured ceramic powder. For the chemical analysis, inductively coupled plasma atomic emission spectroscopy (ICP-AES) was performed. Pressurized sulfuric acid treatment was performed as a sample pretreatment for ICP atomic emission spectroscopy. For X-ray fluorescence analysis, the base material was analyzed using the glass bead method (measurement diameter 30 mm) with a ZSX Peimus2 fluorescence spectrometer, and the component ratios of the base material and the thin film supported on the surface of the base material were confirmed.

[0022] Next, the sintering behavior of ceramic powder with a thin film supported on the surface of a base material was evaluated using thermomechanical analysis (TMA). Figure 3 is an explanatory diagram of the relationship between sintering temperature and shrinkage rate due to sintering. Figure 3 shows the change in shrinkage with respect to the change in firing temperature. In Figure 3, the change in firing shrinkage of Example 1 is shown by the solid line curve C1, the change in firing shrinkage of Comparative Example 1 is shown by the dashed line curve C2, and the change in firing shrinkage of Comparative Example 2 is shown by the dashed line curve C3. Example 1 is a molded alumina sintered body manufactured by the manufacturing method of this embodiment shown in Figure 2. Comparative Example 1 is a molded alumina sintered body manufactured by the same manufacturing method as this embodiment, using alumina and Mn2O3 as a substitute for a manganese-containing complex as materials. Comparative Example 2 is a molded alumina body. As shown in Figure 3, the curve C1 representing the change in firing shrinkage in the molded body of this embodiment shrinks at a lower temperature compared to Comparative Examples 1 and 2. In other words, the molded body of this embodiment was sintered at a lower temperature than Comparative Examples 1 and 2. The TMA was measured using Netch Japan's TMA400SA in air at a heating rate of 5°C / min. The manganese content in the alumina sintered bodies of Example 1 and Comparative Example 1 was 0.8 wt%, and the alumina content was 99.2 wt%.

[0023] Figure 4 is a flowchart of the manufacturing method of the wiring board 100 of this embodiment. In the manufacturing flow of the wiring board 100 shown in Figure 4, first, a printing process is performed in which a conductive paste containing metal powder, which will be the basis of the conductive layer 20, is printed onto a green sheet (step S11). The metal used for the metal powder is appropriately selected depending on the purpose, and examples include copper, platinum, nickel, titanium, iron, chromium, molybdenum, tungsten, and alloys thereof. The green sheet is manufactured by kneading a mixture of alumina powder, which is a ceramic powder containing the manganese compound of this embodiment, in a ball mill, and then forming the resulting kneaded material into a sheet using a known molding method such as the doctor blade method. The alumina powder mixture is a mixture containing appropriate amounts of acrylic resin (binder), dispersant, plasticizer, etc., to which an organic solvent such as toluene is added. Alternatively, the alumina powder mixture may be obtained by kneading alumina, a manganese-containing complex, binder, dispersant, plasticizer, and organic solvent all at once in a ball mill.

[0024] After the printing process, a drying process is performed to dry the green sheet on which the conductive paste has been printed (step S12). The drying conditions in the drying process (heating temperature, drying time, etc.) can be set appropriately according to the material (solvent, etc.) used for the conductive paste. For example, if the conductive paste layer dries naturally at room temperature, the drying process may not be necessary.

[0025] After the drying process, a lamination process is carried out in which multiple green sheets printed with a conductive layer are stacked (step S13). A degreasing and firing process is then performed to remove organic matter from this laminate and solidify it (step S14), completing the manufacturing flow of the wiring board 100.

[0026] Figures 5 and 6 are explanatory diagrams of the EDS (Energy Dispersive X-ray Spectroscopy) of the ceramic sintered body of Example 1. Figures 7 and 8 are explanatory diagrams of the EDS of the ceramic sintered body of Comparative Example 1. Figures 5 and 6 show magnified images of the cross-section of Example 1 taken by EDS. Similarly, Figures 7 and 8 show magnified images of the cross-section of the ceramic sintered body of Comparative Example 1 taken by EDS. In Figures 5 to 8, manganese compounds are represented by white regions. In the images of Figures 5 and 7, a length of 50 μm, which serves as the reference for magnification, is indicated by a white straight line. In the images of Figures 6 and 8, a length of 5 μm, which serves as the reference for magnification, is indicated by a white straight line. In other words, Figures 6 and 8 correspond to further magnified images of Figures 5 and 7, respectively.

[0027] The average particle size of the manganese compound contained in the ceramic sintered body of this embodiment, shown in Figures 5 and 6, is 1 μm or less. Furthermore, the average particle size calculated from the magnified EDS image of Example 1, excluding the portion shown in Figures 5 and 6, was less than 1 μm. On the other hand, the average particle size of the manganese compound contained in the ceramic powder sintered body of Comparative Example 1, shown in Figures 7 and 8, exceeds 1 μm. Thus, the average particle size of the manganese compound contained in the ceramic powder sintered body of this embodiment using a manganese complex is smaller than the particle size of the manganese compound contained in the ceramic powder using Mn2O3, as in Comparative Example 1.

[0028] Figure 9 is an explanatory diagram of the characteristics of the wiring board 100 and substrate 10 using Example 1. Figure 9 shows a table of the components of the substrate 10 and its characteristics, including mechanical properties, thermal properties, and electrical properties. As shown in Figure 9, the substrate 10 of Example 1 has an alumina content of 99.2 wt% and a manganese element content of 0.8 wt%. In addition, the conductive layer 20 when manufactured with the wiring board 100 is formed of CuW.

[0029] Figure 9 shows the mechanical properties of the substrate 10, including flexural strength, hardness, fracture toughness, and Young's modulus. The flexural strength is 450 MPa, the hardness is 19.5 GPa, and the fracture toughness is 3.5 MPa·m. 1 / 2 The Young's modulus is 370 GPa. Figure 9 shows the thermal properties, specifically the thermal conductivity. The thermal conductivity is 17 W / (m·K). Figure 9 also shows the electrical properties, specifically the relative permittivity, dielectric loss, and insulation resistance. The relative permittivity is 10.6, and the dielectric loss when an AC electric field of 1 MHz is applied is 0.2 × 10⁻⁶. -4 Therefore, the insulation resistance at room temperature (25°C) is 2.5 × 10⁻⁶. 14 The pressure is Ω·cm. Note that when the particle size of the manganese compound, such as in Comparative Example 1 shown in Figures 7 and 8, exceeds 1 μm, a dense sintered body is not formed even when fired at 1200°C, and the mechanical properties shown in Figure 9 could not be measured.

[0030] Figure 10 is an explanatory diagram of the relative density of alumina sintered bodies of Examples 1-7 and Comparative Examples 1 and 3, prepared using the ceramic powder of this embodiment. Figure 10 shows the relative density of the alumina sintered body, which changes depending on the amount of manganese element added to the ceramic powder and the firing temperature during sintering. As shown in Figure 10, Examples 1-3 are alumina sintered bodies with a manganese element addition of 0.8 wt%, fired at 1200°C, 1300°C, and 1400°C, respectively. Since the alumina sintered body contains alumina other than manganese, the alumina content of Examples 1-3 is 99.2 wt%. Examples 4 and 5 are alumina sintered bodies with a manganese element addition of 2.3 wt%, fired at 1200°C and 1300°C, respectively. The alumina content of Examples 4 and 5 is 97.7 wt%. Example 6 is an alumina sintered body with a manganese element addition of 5.0 wt% and fired at 1200°C. The alumina content of Example 6 is 95.0 wt%. Example 7 is a sintered body with a manganese element addition of 0.3 wt% and fired at 1400°C. The manganese element content of Example 7 is 99.7 wt%. On the other hand, the relative density of Comparative Example 1, which has a manganese element content of 0.8 wt%, is 91.4% when fired at a firing temperature of 1200°C. Also, the relative density of Comparative Example 3, which has a manganese element content of 2.3 wt%, is 95.0% when fired at a firing temperature of 1200°C. The alumina content of Comparative Example 3 is 97.7 wt%. As shown in Figure 10, the relative densities of Examples 1 to 7, which have firing temperatures of 1200°C or higher, are 96.8% or higher, which is higher than the relative densities of Comparative Examples 1 and 3. Therefore, the sintered bodies of Examples 1 to 7 are formed more densely than the sintered bodies of Comparative Examples 1 and 3.

[0031] Figure 11 is an explanatory diagram illustrating the relationship between sintering temperature and shrinkage rate for Comparative Examples 3-5 using copper (Cu) element. Figure 11 shows the change in shrinkage with change in sintering temperature for Comparative Examples 4 and 5, which use copper element instead of manganese element in Example 1, and for Comparative Example 3 shown in Figure 3. In Figure 11, the change in sintering shrinkage for Comparative Example 4 is shown by the solid line C4, the change in sintering shrinkage for Comparative Example 5 is shown by the dashed curve C5, and similarly to Figure 3, the change in sintering shrinkage for Comparative Example 3 is shown by the dashed curve C3. Comparative Example 4 is a molded alumina sintered body manufactured using a complex containing copper element instead of a manganese element complex, compared to the manufacturing method shown in Figure 2. Comparative Example 5 is a molded alumina sintered body manufactured using alumina and copper oxide CuO as materials, according to the manufacturing method shown in Figure 2. The copper element content in Comparative Examples 4 and 5 is 0.8 wt%, and the alumina content is 99.2 wt%.

[0032] Comparing the curve C1 of Example 1, which uses a manganese-containing complex shown in Figure 3, with the curve C2 of Comparative Example 1, which uses Mn2O3, Example 1 shows a greater sintering shrinkage rate at a lower temperature. In other words, Example 1 is formed into a denser sintered body at a lower temperature. On the other hand, comparing the curve C4 of Comparative Example 4, which uses a copper-containing complex shown in Figure 11, with the curve C5 of Comparative Example 5, which uses CuO, there is no significant difference in the sintering shrinkage rate with respect to temperature.

[0033] Here, it is thought that the following reactions (1) and (2) occur during the sintering of the alumina compounds of Example 1 and Comparative Example 1 that contain manganese. Equation (1) is a reaction equation that represents the change in the valence of manganese in the manganese compound. Equation (2) is a reaction equation between manganese and the base material, alumina.

[0034]

number

[0035] On the other hand, when the alumina compounds of Comparative Examples 4 and 5, which contain copper, are sintered, the reactions shown in equations (3) and (4) below are thought to occur. Equation (3) is the reaction equation between CuO and the base material, alumina. Equation (4) is the equation that shows the change in the valence of copper after reacting with the base material, alumina.

[0036]

number

[0037] In the valence change of manganese or copper shown in formulas (1) and (4) above, the smaller the particle size, the more easily the gaseous oxygen diffuses to the surface and the reaction proceeds. In the reaction between manganese or copper shown in formulas (2) and (3) above and the alumina base material, the reaction proceeds more efficiently and quickly with better dispersibility and a larger contact area. As the reaction between the base material and the sintering aid progresses, the particle size increases. Therefore, in Example 1 and Comparative Example 1, which contain manganese, it is preferable that the reaction with the base material shown in formula (2) above proceeds after the valence change reaction shown in formula (1). Similarly, in Comparative Examples 4 and 5, which contain copper, it is preferable that the reaction with the base material shown in formula (3) above proceeds after the valence change reaction shown in formula (4). However, in Comparative Examples 4 and 5, which contain copper, as shown in formula (3), the valence change reaction shown in formula (4) above does not occur unless the reaction between copper and the alumina base material has occurred first. Therefore, as shown in the comparison of curves C4 and C5 in Figure 11, it is considered that there is no significant difference in the firing shrinkage rate with respect to temperature between Comparative Example 4, which uses a complex containing copper, and Comparative Example 5, which uses CuO. On the other hand, in Example 1 and Comparative Example 1, which contain manganese, as shown in formula (1) above, formula (2) above occurs after the valence change of manganese occurs. In other words, by using a complex containing manganese, formula (1) above proceeds smoothly due to good dispersibility and a large surface area, and the reaction between manganese and alumina in formula (2) above reacts efficiently and quickly due to the large contact area with the base material, and it is considered that the firing shrinkage rate of Example 1 at the same temperature is improved compared to the firing shrinkage rate of Comparative Example 1.

[0038] As described above, the base material 10 of the present embodiment is formed of an alumina sintered body containing a manganese (Mn) element. The manganese element contained in the base material 10 is contained as a manganese compound having an average particle diameter of 1 μm or less. In the base material 10 of the present embodiment, the manganese element is dispersed in the alumina sintered body as a small manganese compound having an average particle size of 1 μm or less and functions as a sintering aid. Therefore, even if the amount of the manganese compound contained in the material of the alumina sintered body is small, sintering during the production of the alumina sintered body is promoted. As a result, the firing temperature of the alumina sintered body of the present embodiment can be lowered.

[0039] In addition, the content of the manganese element contained in the base material 10 of the present embodiment is 5 wt% or less. In the base material 10 of the present embodiment, since the manganese element is dispersed in the alumina sintered body as a small manganese compound, even if the content of the manganese element is as low as 5 wt% or less, the temperature during sintering of the alumina sintered body decreases.

[0040] In addition, the dielectric loss when an alternating current electric field of 1 MHz is applied to the alumina sintered body forming the base material 10 of the present embodiment is, as shown in FIG. 9, 0.2×10 -4 (<1.0×10 -4 ). In the alumina sintered body of the present embodiment, the dielectric loss when an alternating current electric field is applied can be made as small as 1.0×10 -4 or less.

[0041] In addition, the insulation resistance of the alumina sintered body forming the base material 10 of the present embodiment is, as shown in FIG. 9, 2.5×10 14 Ω·cm (>1.0×10 14 Ω·cm). In the alumina sintered body of the present embodiment, the insulation resistance can be made as high as 1.0×10 14 Ω·cm or more.

[0042] Furthermore, the flexural strength of the alumina sintered body forming the base material 10 of this embodiment is 450 MPa (≧450 MPa), as shown in Figure 9, and the hardness is 19.5 GPa (>19.0 GPa). In the alumina sintered body of this embodiment, the flexural strength can be made high at 450 MPa, and the hardness can be made high at 19 GPa.

[0043] Furthermore, as shown in Figure 1, the wiring board 100 of this embodiment comprises four substrates 10 and three conductive layers 20. Each conductive layer 20 is formed of multiple conductive films. The conductive film 21 contains copper (Cu) and at least one of tungsten (W) and molybdenum (Mo). In the wiring board 100 of this embodiment, manganese elements are well dispersed in the alumina sintered body as manganese compounds with an average particle size of 1 μm or less. Therefore, the wiring board 100 can be sintered at a lower temperature.

[0044] <Second Embodiment> Figure 12 is a flowchart of the method for producing alumina powder according to the second embodiment. In the production flow shown in Figure 12, first, alumina powder as the base material, a solvent, and a complex containing manganese are prepared (step S21). Next, a kneading step is performed in which the solvent and base material are added to the complex and stirred (step S22). The paste after stirring is dried using an evaporator (step S23). Drying using an evaporator is performed under reduced pressure to prevent decomposition of the complex by heating, and while stirring to prevent sedimentation of the material powder. A degreasing step is performed to degrease the powder, which is a mixture of alumina powder and complex after drying (step S24). The degreasing step is performed under the same conditions as in the first embodiment to produce alumina powder that will be the basis of the base material 10.

[0045] <Modified form of this embodiment> The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit, for example, the following modifications are also possible.

[0046] In the first and second embodiments described above, an example of an alumina sintered body containing a manganese compound with an average particle size of 1 μm or less, and a method for manufacturing the alumina sintered body were explained. However, the method for manufacturing the alumina sintered body is modifiable. The alumina sintered body may be used for materials other than the base material 10 of the wiring board 100. The alumina sintered body may be manufactured using materials other than complexes containing manganese.

[0047] The manganese content in the alumina powder may be greater than 5 wt%. However, to avoid impairing the properties of the alumina base material, the manganese content is preferably 5 wt% or less. Furthermore, as shown in Figure 10, to improve the relative density, the manganese content of the alumina powder is preferably 2.3 wt% or less, and more preferably 0.8 wt% or less.

[0048] The method for producing an alumina sintered body containing manganese element shown in Figure 212 is an example and can be modified to include a kneading step of mixing alumina as a base material with a complex containing manganese element, and a degreasing step of degreasing the mixture of alumina and the complex. For example, the drying of the mixture and the degreasing step may be performed in a single step, or the dried powder may be degreased after molding. In the process of step S2 in the manufacturing flow of the first embodiment shown in Figure 2, the ceramic powder, binder, and solvent may be kneaded by a ball mill instead of a three-roll mill. Alternatively, in the kneading step, the alumina, the complex containing manganese element, the binder, the dispersant, the plasticizer, and the organic solvent may be kneaded together in a ball mill.

[0049] From the viewpoint of film-forming properties and solubility, fatty acid salts are preferred as the type of manganese-containing complex. However, the complex can be modified to the extent that it is soluble in organic solvents such as nitrates, sulfates, and ammonium salts, or in water.

[0050] The dielectric loss of the alumina sintered body in Example 1 of the above embodiment when an AC electric field of 1 MHz is applied is 0.2 × 10⁻⁶, as shown in Figure 9. -4 However, 0.2 × 10 -4It may be larger than this. The dielectric loss of an alumina sintered body when an AC electric field of 1 MHz is applied is 1.0 × 10⁻⁶. -4 The following is preferable. The insulation resistance of the alumina sintered body of Example 1 is 2.5 × 10⁻⁶. 14 It was Ω·cm, but 2.5 × 10 14 It may be less than Ω·cm. The insulation resistance of the alumina sintered body is 1.0 × 10⁻⁶. 14 A strength of Ω·cm or higher is preferred. The flexural strength of the alumina sintered body in Example 1 was 450 MPa, but it may be less than 450 MPa. A flexural strength of 450 MPa or higher is preferred for the alumina sintered body. The hardness of Example 1 was 19.5 GPa, but it may be less than 19.5 GPa. A hardness of 19.0 GPa or higher is preferred for the alumina sintered body.

[0051] The embodiments of this specification have been described above based on the embodiments and modifications described above. The embodiments described above are for the purpose of facilitating understanding of this specification and do not limit it. This specification may be modified and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in this specification. Furthermore, any technical features that are not described as essential in this specification may be deleted as appropriate.

[0052] The present invention can also be realized in the following forms. [Application Example 1] A sintered alumina body containing manganese (Mn) element, An alumina sintered body characterized in that the element manganese is contained as a manganese compound with an average particle size of 1 micrometer (μm) or less. [Application Example 2] The alumina sintered body described in Application Example 1, An alumina sintered body characterized by having a manganese element content of 5 wt% or less. [Application Example 3] An alumina sintered body as described in Application Example 1 or Application Example 2, The dielectric loss when an AC electric field of 1 MHz is applied is 1.0 × 10⁻⁶. -4 An alumina sintered body characterized by the following: [Application Example 4] An alumina sintered body according to any one of Application Examples 1 to 3, Insulation resistance is 1.0 × 10 14 An alumina sintered body characterized by having a density of Ω·cm or greater. [Application Example 5] An alumina sintered body according to any one of Application Examples 1 to 4, An alumina sintered body characterized by having a flexural strength of 450 MPa or more and a hardness of 19 GPa or more. [Application Example 6] A wiring board, An insulating layer formed from an alumina sintered body as described in any one of Application Examples 1 to 5, An electrode comprising copper (Cu) and at least one of tungsten (W) and molybdenum (Mo), A wiring board characterized by comprising the following features. [Explanation of Symbols]

[0053] 10…Base material (alumina sintered body, insulating layer) 20...Conductive layer 21... Conductive film 100... Wiring board C1~C5... Curve of firing shrinkage rate

Claims

1. A sintered alumina body containing manganese (Mn) element, An alumina sintered body characterized in that the element manganese is contained as a manganese compound with an average particle size of 1 micrometer (μm) or less.

2. The alumina sintered body according to claim 1, An alumina sintered body characterized by having a manganese element content of 5 wt% or less.

3. The alumina sintered body according to claim 1, The dielectric loss when an AC electric field of 1 MHz is applied is 1.0 × 10⁻⁶. -4 An alumina sintered body characterized by the following:

4. The alumina sintered body according to claim 1, Insulation resistance is 1.0 × 10 14 An alumina sintered body characterized by having a density of Ω·cm or greater.

5. The alumina sintered body according to claim 1, An alumina sintered body characterized by having a flexural strength of 450 MPa or more and a hardness of 19 GPa or more.

6. A wiring board, An insulating layer formed from the alumina sintered body described in claim 1, An electrode comprising copper (Cu) and at least one of tungsten (W) and molybdenum (Mo), A wiring board characterized by comprising the following features.

Images