JP3038320B2 - Method for producing aluminum nitride sintered body for circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aluminum nitride sintered body for a circuit board, and more particularly, to an aluminum nitride for a circuit board which is produced by low-temperature sintering of an aluminum nitride ceramic having less sintering unevenness and color unevenness. The present invention relates to a method for manufacturing a sintered body.

[0002]

2. Description of the Related Art Electronic circuits are mainly composed of elements such as ICs, substrates and wiring. In recent years, the speeding up of electronic circuits,
As the miniaturization and the increase in output have progressed, the heat value of the element has become a large value that cannot be ignored. In order to cope with this, a circuit board made of aluminum nitride (AlN) ceramics having high thermal conductivity has been developed, and the production amount thereof is increasing year by year. However, despite the fact that AIN ceramics have excellent characteristics as a circuit substrate, the mainstream of ceramic substrates is still made of alumina. There are several factors in this regard, but the biggest problem is the high cost. Specifically, factors such as the high price of the raw material powder, the high energy cost due to the sintering temperature higher than that of alumina, and the expensive post-processing are cited as factors.

[0003] Under such circumstances, many improvements regarding AIN sintered bodies have been attempted. For example, regarding additives related to improvement of thermal conductivity and improvement of sinterability, JP-A-61-117160 and JP-A-61-20995 have been disclosed.
No. 9 discloses addition of a rare earth and / or alkaline earth, and Japanese Patent Application Laid-Open No. 62-153173 proposes addition of a rare earth and / or alkaline earth and a transition metal compound. Furthermore, at the annual meeting of the Ceramic Society of Japan in May 1991, 140
It is disclosed that an AlN sintered body can be obtained under sintering conditions of 0 ° C. for 96 hours. As a result of such research, what initially required a temperature of 1800 ° C. or more for AIN sintering has become possible at a laboratory level under conditions of about 1600 ° C. for about 6 hours. .

It is necessary to consider the method of lowering the sintering temperature while taking into consideration the entire manufacturing process including the characteristics of the AIN powder and the composition of the additives. In general, fine AIN powder having a small particle size distribution is suitable for low-temperature sintering, but has problems of increasing oxygen impurities and bulkiness. On the other hand, as additives for low-temperature sintering, fluorides, borides, alkali metal compounds, and the like are known in addition to the use of rare earth elements and alkaline earth elements in combination. However, sintering at a low temperature for a short period of time does not provide sufficient densification only by using a combination of a rare earth and an alkaline earth. In addition, when a fluoride-based additive is used, a foreign substance layer is deposited on the surface of the sintered body, and thus cannot be used without post-processing. Furthermore, when a compound containing boron is used, it reacts with tungsten as a conductor component to produce tungsten boride having high electric resistance. In addition, when an alkali metal compound is added, there are problems such as a decrease in thermal conductivity of the sintered body and a change in electric resistance.

Therefore, when the method is considered assuming a method which is close to the condition at the time of mass production, the characteristics of the sintered body greatly vary.
Actually, the problem that the production cost of the AIN sintered body is high, such as the inevitable secondary processing and the sintering time of 6 hours or more, has not yet been solved.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of these circumstances, and has been developed in view of the above.
An object of the present invention is to reduce the production cost by enabling the production of an N sintered body by sintering at a low temperature and for a short time.

[0007]

According to the present invention, there is provided a method for producing an aluminum nitride sintered body for a circuit board, comprising the steps of: using an additive containing an alkaline earth metal element and a rare earth element; Is 2.0 g / cm ³ or more, and the additive is prepared in a ratio of 1.0 to 9.9 parts by weight in terms of oxide with respect to 100 parts by weight of the aluminum nitride. Sinter at 1550 ° C or higher.

[0008] The preparation of the compact comprises a step of compression-molding a mixed powder obtained by mixing the additive in a solution contained in the solvent with the aluminum nitride powder and then removing the solvent. The compound containing the alkaline earth metal element and the rare earth element as the additive is selected from the group consisting of nitrate, alkoxide and sol, respectively, and the solvent is a polar solvent.

The aluminum nitride powder has a specific surface area of 3.0 to 4.0 m ² / g, and the compact does not contain an alkali metal compound, a fluorine compound and a boron-containing compound.

Further, the method for producing an aluminum nitride sintered body for a circuit board according to the present invention is a method for manufacturing an alkaline earth metal additive and a rare earth additive dissolved in a polar solvent selected from the group consisting of nitrates, alkoxides and sols. Is mixed with an aluminum nitride powder, a transition metal component and a binder powder, and then the polar solvent is removed.
The additive is added in an amount of 1.0 to 9 in terms of oxide based on 0 parts by weight.
9 parts by weight of the transition metal component in an amount of 0.05 to 1.
A step of obtaining a mixed powder containing 1 part by weight, a step of compressing the mixed powder, and then removing a binder by heating to prepare a molded body having a molded body density of 2.0 g / cm ³ or more; Sintering the molded body at 1550 to 1600 ° C.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In general, to obtain an AlN sintered body, a mixed powder obtained by adding a binder powder and a desired additive to an AlN powder is prepared, and after compression-molding the mixture, the molded body is heated. Perform binder removal and sintering. In this case, the sintering temperature must be 1800 ° C. or higher. For this reason, in the related art, the sintering temperature is lowered by using an additive such as a sintering aid. However, a dense AlN sintered body is formed by low-temperature sintering at 1600 ° C. or less on a plant scale. Nothing is as effective as it can be. The present inventors focused on the step of compression molding of raw material powder before sintering and obtained trial and error to obtain a more compact AlN sintered body than low-temperature sintering. By molding the raw material powder so that the density of the compact after compression molding and binder removal or before sintering is 2.0 g / cm ³ or more, the sintering temperature is 1600 ° C. or less and the sintering time is 2 hours. It has been found that a dense AlN sintered body can be obtained even under sintering conditions within a time period, and that the thermal conductivity and strength of the sintered body show satisfactory values even on a plant scale.

It is quite difficult to obtain an AlN compact having a compact density of 2.0 g / cm ³ or more by a plant-scale operation by selecting the compacting pressure and the raw material AlN powder. In the present invention, A
By mixing the 1N powder and the additive in a solution state in which the additive is dissolved in a solvent having good dispersibility of the AlN powder, the filling rate of the mixed powder is improved, and the density of the compact is 2.0 g.
/ Cm ³ or more. Specifically, at least a part of the additive is dissolved in a solvent and mixed with the AlN powder, and after mixing, the solvent is removed from the mixed powder to improve the filling rate of the mixed powder.

Hereinafter, a preferred embodiment of the method for producing an AlN sintered body according to the present invention will be described in detail.

In the present invention, the BET specific surface area is from 3.0 to 3.0.
It is preferable to use 4.0 m ² / g of AIN powder. 3.
If it is less than 0 m ² / g, the particle size is too coarse and sintering at low temperature becomes difficult. If it exceeds 4.0 m ² / g, it becomes bulky and requires many organic solvents and binders during wet mixing and the like, and the amount of residual carbon after debinding increases, making sintering difficult. Occurs. The AlN powder preferably has an impurity oxygen content of 0.60 to 2.20% by weight, more preferably 0.90 to 1.80% by weight.

[0015] The AlN powder is mixed with an inorganic additive and a binder as described below.
A solvent is used when mixing the additives with the AlN powder. As this solvent, a solvent having good dispersibility of the AlN powder is used. The dispersibility of AlN powder is good in polar solvents, for example, alcohol solvents such as methanol, ethanol, propanol and butanol; ketone solvents such as acetone and methyl ethyl ketone; ester solvents such as ethyl acetate are used; An aqueous solvent is used only when a special surface treatment is applied.

The inorganic additive used in the present invention contains an alkaline earth metal component and a rare earth component, and these components function as a sintering aid and a high thermal conductivity agent. Since these components are mixed with the AlN powder in a liquid phase dissolved in the above-mentioned solvent, the components need to be dissolved in the above-mentioned solvent. For this reason, those in the form of nitrate, chloride, alkoxide, sol and the like are used. For example, yttrium nitrate (Y (N
_{O 3) 3 · 6H 2 O} ), calcium nitrate (Ca (NO
_{3) 2 · 4H 2 O)} , yttrium sol alcohol such as ethanol as a dispersion medium, such as yttrium alkoxide are preferable. The sol is slightly different from the solution strictly speaking, but is included in the solution used in the present invention because the sol is a solution having the same effect in improving the filling ratio of the mixed powder in the present invention. . The total amount of these additives is set so as to be 1.0 to 9.9 parts by weight in terms of oxide based on 100 parts by weight of AlN powder. 1.0
If the amount is less than parts by weight, a sufficient effect of addition cannot be obtained, and 9.9 is obtained.
If the amount exceeds the weight part, the thermal conductivity is significantly reduced. At least a part, preferably the whole amount, of the powder of these additives is charged into an appropriate amount of the above-mentioned solvent to form a liquid phase, and mixed with the AlN powder. The sol can be directly mixed with the AlN powder.

In the present invention, in addition to the above additives, T
i, Nb, Zr, Ta, W, Mo, Cr, Fe, Co,
A transition metal component such as Ni can be added. The transition metal component has an effect of suppressing unevenness such as unevenness of sintering and unevenness of color, and blackening the sintered body. In addition, the mechanical strength and radiation of the AlN sintered body are improved. The transition metal component can be added, for example, as a metal compound such as an oxide, nitride, carbide, oxycarbide, or oxynitride. In particular, it is desirable that the compound has conductivity in the sintered body. Examples of such conductive transition metal compounds include, for example,
Metals of W and Mo, and nitrides or carbides of elements selected from Zr, Ti, Nb, and Ta can be given. The added amount of the transition metal component is desirably 0.05 to 1.1 parts by weight in terms of oxide based on 100 parts by weight of AlN powder. If the amount exceeds 1.1 parts by weight, electrical characteristics may be degraded. If the amount is less than 0.05 parts by weight, a sufficient effect of addition cannot be obtained. The mixing of the transition metal component and the AlN powder may be performed simultaneously with the solution of the additive composed of the alkaline earth metal component and the rare earth component described above or individually.
Efficiency is improved when the transition metal component is dispersed in a solution of the alkaline earth metal component and the rare earth component and mixed with the AlN powder.

Further, if necessary, various additives used in ordinary powder metallurgy may be used according to a conventional method. However, a fluorine compound, an alkali metal component and a boron compound are not added. The fluorine compound produces a surface layer made of an oxide on the surface of the AlN sintered body, and the alkali metal lowers the insulation of the AlN sintered body. In addition, the boron compound, when using a tungsten component as a conductor component,
By reacting with this, tungsten boride is generated, and the conductivity of the AlN sintered body is reduced.

In order to improve the moldability of the AlN mixed powder, a binder is used in the present invention. As the binder, for example, a butyral-based, acryl-based, methacryl-based, or PVB-based binder is used. The amount of the binder to be added varies depending on the particle size of the AlN powder used, but is 2 to 12% by weight, more preferably 4 to 10% by weight, based on the total amount of the mixed powder of the above additive and AlN powder. The binder is, for example, an alcohol such as ethanol or 1-butanol.
It is preferable to disperse in the AlN powder using a solvent having a good dispersibility of the N powder. It is not preferable to use a solvent having poor dispersibility such as xylene. When a solvent having poor dispersibility such as xylene is used when a binder is added to a mixture of the above-described additive and AlN powder, the dispersed additive is aggregated, and the compressibility of the mixed powder is reduced. Also, the binder is not sufficiently dispersed. Therefore, the use of a solvent that does not dissolve the additive must be avoided even after the additive is sufficiently dispersed in the AlN powder using alcohol or the like. In other words, it is important to use the above-mentioned polar solvent in the mixing operation when obtaining the mixed powder of the final composition to be subjected to compression molding.

Al mixed with the above additives and binder
The N mixed powder is subjected to compression molding after granulation by removing the solvent used. In the present invention, 100 to 500MP
A compact having a compact density of 2.0 g / cm ³ or more can be obtained by compression molding at a compacting pressure of about a. The molding step may be performed in a plurality of times. For example, the density is increased by forming once into a sheet and then pressing again to increase the density of the molded body (density after debinding) to 2.0 g / cm ^3.
You may set so that it may become above.

The compact obtained by compression-molding the mixed powder is debindered by heating. Debinding is usually achieved by heating to a maximum temperature of 1000 ° C. or less. When a conductive metal such as tungsten or molybdenum is not contained in the AlN mixed powder, the binder can be removed by heating in an atmosphere containing oxygen. Heat with. As the non-oxidizing atmosphere, an inert gas such as nitrogen or argon, or a gas containing hydrogen, carbon dioxide or the like can be used. When the conductive metal is not contained in the AlN mixed powder, the heating temperature is desirably up to 500 ° C.

The compact after debinding is housed in a sintering vessel and sintered at a temperature of 1550 to 1600 ° C. in a non-oxidizing atmosphere. Atmospheric pressure during sintering is 0.01 to 10.0
Performed at atmospheric pressure. The same non-oxidizing atmosphere as described above can be used. As the sintering container, one made of a heat-resistant material such as AlN, BN, and alumina is used, and a sintering furnace equipped with a heater made of carbon, tungsten, molybdenum, or the like is used. The sintering schedule may be increased monotonically or stepwise to the maximum temperature, and is appropriately selected as needed. The obtained AlN
The sintered body may be subjected to post-processing such as trimming as necessary.

According to the present invention, the molded article having a density of 2.0 g / cm ³ or more after debinding is 1550 to
By sintering at a temperature of 1600 ° C., a sufficiently dense AlN sintered body is obtained, and the time required for sintering can be reduced to about 2 hours. The thermal conductivity of the obtained AlN sintered body is 100 to 120 W / mK, and the four-point bending strength also shows an average value of 300 MPa or more. Therefore, the AlN sintered body manufactured according to the present invention can be used as a high-temperature high-strength material or a heat sink, or can be metalized and used as various circuit boards. For example, DBG,
It can be used for substrates of electric or electronic circuits such as QFP, PGA, BGA, DIP, thin film, and thick film. When the AlN sintered body of the present invention is used for forming an insulating portion of a circuit board, the circuit board has excellent heat dissipation and mechanical strength, has no defects such as peeling or disconnection in a conductor layer, and has a good circuit. Can demonstrate performance. Examples of the conductive material used when forming the circuit board include W, Wo, Pt, Pd, and Ni.

The circuit board is manufactured, for example, by the following method. First, a binder and a solvent are added to the AlN powder and the above-mentioned additives, and they are sufficiently kneaded to form a slurry having a predetermined viscosity. During this time, the disintegration of the AlN powder and the binder and the dissolution and dispersion of the additive proceed. A sheet is formed by a doctor blade method using the obtained slurry, and then dried by heating to remove the solvent to obtain a green sheet. Next, a predetermined circuit pattern is formed on at least one surface of the green sheet using a conductive paste by a method such as screen printing. At this time, when a multilayer circuit is formed, holes for vias for electrical connection between layers are provided in advance in the green sheet, and the holes are filled with a conductive paste by, for example, a press-fitting method. Next, the green sheet on which the conductive circuit is formed is heated in a non-oxidizing atmosphere to remove the binder in the conductive paste. If necessary, a circuit pattern is further formed on the surface, and hot pressing is performed to laminate the green sheets. Thereafter, the binder in the green sheet is removed by heating in a non-oxidizing atmosphere and then sintered. After sintering, trimming, thin-film or thick-film circuit formation, and external electrodes can be formed as necessary.

[0025]

Embodiments of the present invention will be described below in detail.

Example 1 95.7% by weight of yttrium nitrate having a purity of 99.5% was added to 95.7 parts by weight of AlN powder having an impurity oxygen amount of 0.9 wt%, an average particle diameter of 1.1 μm and a specific surface area of 3.1 m ² / g. 3.0 parts by weight in terms of Y ₂ O ₃ , calcium nitrate having a purity of 99.9% is 1.0 parts by weight in terms of CaO, and WO ₃ having an average particle diameter of 0.1 μm and a purity of 99.9% is converted to W. With 0.
1-butanol 1 was added to the mixed powder obtained by adding 3 parts by weight.
50 parts by weight were added, crushed and mixed by a wet ball mill. During this step, yttrium nitrate and calcium nitrate were dissolved in 1-butanol. Thereafter, 1-butanol was removed to obtain a raw material powder. Subsequently, a binder liquid containing a butyral-based binder in an ethanol solvent was weighed in such an amount that the amount of the binder became 6 parts by weight, and added to the raw material powder. Furthermore, after removing ethanol and granulating, it was press-formed at 200 MPa using a uniaxial pressing machine to obtain a formed body. The compact was heated to 500 ° C. in dry air to remove the binder. The molded article density after debinding was 2.02 g / cm ³ . The compact after debinding is housed in a sinter container made of an AIN sintered body,
Using a graphite heater furnace, sintering was performed at 1600 ° C. for 2 hours in a nitrogen gas atmosphere at 1 atm.

The obtained sintered body was black, had no color unevenness or uneven firing, and was measured for density by Archimedes method.
It was densified to 3.28 g / cm ³ . From this sintered body,
A disk having a diameter of 10 mm and a thickness of 3 mm was cut out, and the thermal conductivity was measured at a room temperature of 21 ± 2 ° C. by a laser flash method according to JIS-R1611.
It was K. When the four-point bending strength was measured according to JIS-R1601, the average value was 315 MPa.

(Comparative Example 1) A molding was obtained by repeating the same operation as in Example 1 except that the molding pressure by the uniaxial pressure molding machine was changed to 50 MPa. When the body density was measured, it was 1.8.
It was 7 g / cm ³ . When the sintered body was sintered in the same manner as in Example 1 and the density was measured, the density of the sintered body was 3.24 g / cm ^3.
It was not dense enough. Also, the thermal conductivity is 107
It was as low as W / mK.

(Comparative Example 2) AlN powder 9 used in Example 1
Against 5.7 parts by weight, the Y ₂ O ₃ having an average particle diameter of 0.4μm with a purity 99.9 wt% 3.0 parts by weight, a purity of 99.9%
In the above, CaCO ₃ having an average particle size of 0.5 μm was converted into 1.
0 parts by weight, W having an average particle size of 0.1 μm and a purity of 99.9 wt%
To a mixed powder obtained by adding 0.3 parts by weight of O ₃ in terms of W, 150 parts by weight of 1-butanol was added, crushed and mixed by a wet ball mill, and 1-butanol was removed to obtain a raw material powder. . Subsequently, a binder liquid composed of an acrylic binder and a xylene solvent was weighed and added to the raw material powder so that the binder became 6 parts by weight. After removing xylene and granulating, the mixture was pressure-molded in the same manner as in Example 1 to remove the binder. When the density of the compact was measured,
It was 1.91 g / cm ³ . The molded body from which the binder was removed was placed in a sintering vessel made of an AlN sintered body, and heated in a nitrogen gas atmosphere at 1 atm using a graphite heating furnace.
Sintered at 0 ° C. for 2 hours.

When evaluated by the same method as in Example 1, the obtained sintered body had a density of 3.18 g / cm ³ , insufficient densification, and a low thermal conductivity of 105 W / mK.

Comparative Example 3 AlN Powder 9 Used in Example 1
Against 5.7 parts by weight, the Y ₂ O ₃ having an average particle diameter of 0.4μm with a purity 99.9 wt% 3.0 parts by weight, a purity of 99.9%
In the above, CaCO ₃ having an average particle size of 0.5 μm was converted into 1.
0 parts by weight, W having an average particle size of 0.1 μm and a purity of 99.9 wt%
To a mixed powder obtained by adding 0.3 parts by weight of O ₃ in terms of W, 150 parts by weight of 1-butanol was added, crushed and mixed by a wet ball mill, and 1-butanol was removed to obtain a raw material powder. . Subsequently, a binder solution comprising a butyral-based binder and an ethanol solvent was weighed and added to the raw material powder so that the binder became 6 parts by weight. After removing the ethanol and granulating, the mixture was pressure-molded in the same manner as in Example 1 to remove the binder. The measured density of the compact was 1.90 g / cm ³ . The molded body from which the binder was removed was placed in a sintering container made of an AlN sintered body, and was heated in a nitrogen gas atmosphere at 1 atm using a graphite heating furnace.
Sintered at 600 ° C. for 2 hours.

When evaluated by the same method as in Example 1, the obtained sintered body had a density of 3.17 g / cm ³ , insufficient densification, and a low thermal conductivity of 103 W / mK.

(Comparative Example 4) AlN powder 9 used in Example 1
Yttrium nitrate having a purity of 99.5 wt% is converted to Y ₂ O ₃ by 3.0 parts by weight, and the purity is 99.9% based on 5.7 parts by weight.
1.0 part by weight calculated as CaO of calcium nitrate, a WO ₃ of purity 99.9 wt% in average particle size 0.1μm in a mixed powder obtained by adding 0.3 parts by weight W terms, 1-butanol 150 The mixture was crushed and mixed by a wet ball mill, and 1-butanol was removed to obtain a raw material powder. Subsequently, a binder liquid composed of an acrylic binder and a xylene solvent was weighed and added to the raw material powder so that the binder became 6 parts by weight. After removing xylene and granulating, the mixture was pressure-molded in the same manner as in Example 1 to remove the binder. The measured density of the compact was 1.88 g / cm ³ . The molded body from which the binder was removed was placed in a sintering container made of an AlN sintered body, and was heated using a graphite heat furnace.
Sintering was performed at 1600 ° C. for 2 hours in a nitrogen gas atmosphere at 1 atm.

When evaluated by the same method as in Example 1, the obtained sintered body had a density of 3.16 g / cm ³ , insufficient densification, and a low thermal conductivity of 101 W / mK.

(Comparative Example 5) AlN powder 9 used in Example 1
Yttrium nitrate having a purity of 99.5 wt% is converted to Y ₂ O ₃ by 3.0 parts by weight, and the purity is 99.9% based on 5.7 parts by weight.
To a mixed powder obtained by adding 1.0 part by weight of calcium nitrate in terms of CaO and 0.3 part by weight in terms of W of WO ₃ having an average particle diameter of 0.1 μm and a purity of 99.9 wt%.
After adding 0 parts by weight, crushing and mixing with a wet ball mill, xylene was removed to obtain a raw material powder. Subsequently, a binder liquid composed of an acrylic binder and a xylene solvent was weighed and added to the raw material powder so that the binder became 6 parts by weight. Example 1 after removing xylene and granulating.
Pressure molding was performed in the same manner as described above, and the binder was removed. The measured density of the compact was 1.83 g / cm ³ . The molded body from which the binder was removed was accommodated in a sintering container made of an AlN sintered body, and sintered at 1600 ° C. for 2 hours in a nitrogen gas atmosphere at 1 atm using a graphite furnace.

When evaluated by the same method as in Example 1, the obtained sintered body had a density of 3.10 g / cm ³ , insufficient densification, and a low thermal conductivity of 99 W / mK.

[0037] (Example 2) impurity oxygen amount 1.3 wt%, an average particle diameter of 1.3 .mu.m, with respect to AlN powder 96.65 parts by weight of the specific surface area of _{^{3.5m 2 / g, Y 2 O}} 3 is 2. Yttrium sol in an amount of 29 parts by weight (50
g of Y ₂ O ₃ is contained in the ethanol dispersion medium),
99.9% pure calcium nitrate is converted to 0.7 as CaO.
6 parts by weight, WO having an average particle diameter of 0.1 μm and a purity of 99.9%
To a mixed powder obtained by adding 0.3 parts by weight of ₃ to W was added 140 parts by weight of ethanol, and the mixture was pulverized and mixed by a wet ball mill, and then ethanol was removed to obtain a raw material powder. Subsequently, a binder solution comprising a butyral-based binder and an ethanol solvent was added to the raw material powder to form a binder.
It was weighed so as to become parts by weight and added. After removing ethanol and granulating, a green compact was formed under uniaxial pressure of 200 MPa. The green compact was heated to 500 ° C. in dry air to remove the binder. The molded article density after debinding was 2.12 g / cm ³ . The compact after debinding was housed in a sintering vessel made of an AlN sintered body, and sintered at 1600 ° C. for 2 hours in a nitrogen atmosphere of 1 atm using a graphite heater furnace.

The obtained sintered body was black, was free from color unevenness and baking unevenness, and was evaluated by the same method as in Example 1. The density was 3.29 g / cm ³ and the thermal conductivity was high. 11
It was 7 W / mK. The average value of the four-point bending strength is 318M.
Pa.

Example 3 Nitric acid having a purity of 99.5% by weight based on 93.71 parts by weight of AlN powder having an impurity oxygen amount of 1.8% by weight, an average particle size of 0.9 μm and a specific surface area of 3.9 m ² / g. 4.49 parts by weight of yttrium in terms of Y ₂ O ₃ , purity 9
9.9% by weight of calcium nitrate is 1.50 parts by weight in terms of CaO, WO ₃ having an average particle size of 0.1 μm and a purity of 99.9% by weight.
To a mixed powder obtained by adding 0.3 parts by weight in terms of W,
160 parts by weight of 1-butanol was added, crushed and mixed by a wet ball mill, and then 1-butanol was removed to obtain a raw material powder. Subsequently, a binder liquid comprising a butyral-based binder and an ethanol solvent was weighed and added to the raw material powder so that the amount of the binder became 6 parts by weight. After removing ethanol and granulating, a green compact formed under uniaxial pressure of 500 MPa was obtained.

The green compact was heated to 500 ° C. in dry air to remove the binder. The molded article density after debinding was 2.18 g / cm ³ . The compact after debinding is housed in a sintering vessel made of an AlN sintered body, and is heated in a nitrogen gas atmosphere of 1 atm using a graphite heater furnace.
Sintered at 1550 ° C for 2 hours.

The obtained sintered body was black, was free from color unevenness and baking unevenness, and was evaluated by the same method as in Example 1. The density was 3.29 g / cm ³ and the thermal conductivity was high. 11
It was 3 W / mK. The average value of the four-point bending strength is 313M.
Pa.

(Example 4) The same AlN powder 9 as in Example 2
To 6.65 parts by weight, 2.29 parts by weight of yttrium nitrate having a purity of 99.5% in terms of Y ₂ O ₃ , 0.76 parts by weight of calcium nitrate having a purity of 99.9% by weight in terms of CaO, and an average particle diameter of 0. To a mixed powder obtained by mixing 0.3 parts by weight of TiO ₂ having a purity of 99.9 wt% with 1 μm in terms of Ti, 6 parts by weight of an acrylic binder and 14 parts by weight of an alcohol solvent 14
It was dispersed in 0 parts by weight to prepare a slip having a viscosity of about 5000 CPS. Subsequently, a green sheet having a uniform thickness of about 0.3 mm was prepared from the slip by a doctor blade method. Subsequently, the green sheet was cut into a predetermined size, and a via hole for obtaining electrical connection between layers was formed in each green sheet. A tungsten paste containing tungsten particles having a diameter of 0.8 μm at a ratio of 50 wt% was press-fitted into the via hole and filled. A tungsten paste was screen-printed on the green sheet in which the via hole was formed to form a pattern of a conductive circuit.

Each green sheet obtained by such a method was laminated and integrated by hot pressing. Thereafter, external processing was performed, and heating was performed to a maximum temperature of 700 ° C. in a nitrogen atmosphere to remove the binder. When measuring the green density of the green sheet only part without the conductor part,
2.01 g / cm ³ . The laminate after debinding is placed in a container made of an AlN sintered body, and sintered in a nitrogen atmosphere at 1600 ° C. for 2 hours using a sintering furnace having a carbon heater, thereby obtaining an AlN for a semiconductor device. A sintered body package was obtained.

The obtained package was free from warpage, undulation, cracks and blisters, had a smooth surface, and was observed with a scanning electron microscope (SEM) to find that both the AlN layer and the W layer were sufficiently dense. Was.

(Example 5) After three doctor sheets of the same composition obtained by the same method as in Example 4 were laminated by a hot press, they were heated to a maximum temperature of 700 ° C in a nitrogen atmosphere.
The binder was removed. Laminate after debinding
It was placed in a container made of N sintered body and sintered at 1580 ° C. for 2 hours in a nitrogen atmosphere using a sintering furnace having a heater made of carbon. The obtained AlN sintered body was processed to 35 × 35 ×
A 0.7 mm plate was obtained. This plate was heated in air at 1130 ° C. for 3 hours to form an α-
An Al ₂ O ₃ layer was formed. Subsequently, a copper plate containing 400 ppm of oxygen was brought into contact with one surface of the sintered plate, and heated in a nitrogen gas atmosphere containing 7 ppm of oxygen to 1070 ° C.
For 3 minutes to join the sintered body plate and the copper plate to obtain a circuit board. When the bonding interface of the obtained circuit board was observed, it was firmly bonded, and the peel strength was measured. As a result, it was as high as 9 kgf / cm.

[0046]

As described above, according to the present invention, 1
By sintering in a low temperature range of 550 to 1600 ° C., an AlN sintered body having stable characteristics with little unevenness in firing and color is obtained. Further, the sintering time can be shortened, and the manufacturing cost of the AIN sintered body can be reduced. By using the AlN sintered body obtained by the present invention, a high-speed and high-power semiconductor device with greatly improved performance and reliability can be manufactured at low cost.

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Fumio Ueno 1 Toshiba, Komukai Toshiba-cho, Saisaki-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba R & D Center (56) References JP-A-8-81264 Hei 4-104961 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C04B 35/581-35/5835

Claims (2)

(57) [Claims] 1. An additive comprising an alkaline earth metal element and a rare earth element comprises a nitrate, an alkoxide and a sol.
Mixed with a powder of aluminum nitride, a transition metal component and a binder in a liquid phase dissolved in a polar solvent in a form selected from the group
Combined by removing the polar solvent, in terms of oxide with respect to aluminum nitride 100 parts by weight from 1.0 to 9.
9 parts by weight of the above additive and 0.05 to 1.1 in terms of element.
A process for obtaining a mixed powder containing the transition metal component in parts by weight.
And compression molding the mixed powder at 100 to 500 MPa.
After heating, the binder is removed by heating,
An aluminum nitride sintered body for a circuit board, comprising: a step of preparing a molded body of 2.0 g / cm ³ or more ; and a step of sintering the molded body at 1550 to 1600 ° C. Manufacturing method. Wherein a specific surface area of the end the aluminum nitride powder
Is 3.0~4.0m ² / g, the molded product, the alkali metal compound The process of claim 1, wherein the free of fluorine compounds and boron containing compounds.