JPS60239368A - Manufacture of aluminum nitride sintered body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for manufacturing an aluminum nitride sintered body.

(Prior art) Aluminum nitride has excellent high-temperature corrosion resistance against molten metal, has excellent heat resistance at high temperatures, and exhibits high strength at high temperatures, so it is used in metal melting crucibles, high-temperature heat-resistant jigs, gas turbine engine parts, etc. There is an application field as a high-temperature member. Furthermore, aluminum nitride is expected to be applied as a heat dissipating member utilizing its high thermal conductivity and electrical insulation properties, particularly as a heat dissipating substrate material in electronic engineering. In other words, in the semiconductor industry, it is expected to be developed as a heat dissipation substrate to suppress the temperature rise of silicon chips and the like due to the high density and high integration of ICs, LSIs, etc.

However, in order to fully utilize these characteristic properties, a highly pure and dense aluminum nitride sintered body is required. Aluminum nitride has no liquid phase at normal pressure (2
It is difficult to sinter with aluminum nitride alone because it sublimates and decomposes at 450°C. For example, Ceramic Bu
l 1etin, vol, 40, /167
(1961) l', 160 as shown in 423
At 0°C and 1800°C, approximately 5XlO' to Hg, respectively.
It has a high decomposition vapor pressure of about 5 x 10-"+ mHg. Therefore, in order to obtain a high-density aluminum nitride sintered body, conventionally, aluminum nitride-aluminum-based nitriding reaction sintering, hot pressing, or additives have been used. Research has been carried out using methods such as pressureless sintering.

However, in the case of aluminum nitride-aluminum-based nitriding reaction sintering, the characteristics of aluminum nitride cannot be utilized because unreacted metallic aluminum remains. Hot pressing also has the disadvantage that it is difficult to manufacture products with complex shapes or large products, and costs are high. In the case of pressureless sintering using additives, it is necessary to fill aluminum nitride powder as a pawl powder in order to suppress sublimation decomposition of aluminum nitride, as shown in Japanese Patent Application Laid-Open No. 50-23411. Since this aluminum nitride powder needs to be used as a nail powder, a large amount of aluminum nitride powder adheres to the aluminum nitride sintered body, resulting in poor dimensional accuracy after sintering. It is necessary to adjust the surface smoothness, etc. In addition, when applied as a high thermal conductivity insulating substrate for electronic circuits, when sintering an aluminum nitride molded body containing a metal conductor, or when producing an aluminum nitride substrate containing multilayer wiring, aluminum nitride nail powder is used as a conductive metal. This becomes a problem because it adheres to the Moreover, there are problems such as the density of aluminum nitride, warping, waviness, and other conditions after sintering that change depending on the filling state of the aluminum nitride powder, which is the nail powder.In addition, the use of expensive aluminum nitride powder as the nail powder is costly. There are disadvantages such as being expensive.

During pressureless sintering of an aluminum nitride compact (sintering in a nitrogen gas atmosphere of 1 atm), aluminum nitride changes as shown in equation (1): AJN (solid) → Al (liquid) + 10 N, 2 ( gas)··
- (1) Since sublimation and decomposition of AJN occurs, the sintered body becomes porous and a high-density aluminum nitride sintered body cannot be obtained. As a result of intensive research, we found that by creating a high-pressure nitrogen gas atmosphere when sintering aluminum nitride, the reaction in the direction of the right side of equation (1) is suppressed, so that the sublimation decomposition of aluminum nitride is suppressed. It has been discovered that a high-quality aluminum nitride sintered body can be obtained without becoming porous.

Therefore, a high-density aluminum nitride sintered body could be obtained simply by placing it in a sintering setter, without using expensive aluminum nitride nail powder as in the conventional pressureless sintering method. Moreover, since the surface smoothness and dimensional accuracy of this aluminum nitride sintered body are extremely good, there is no need to adjust the dimensions by processing such as cutting or polishing after sintering, which is effective in reducing costs.

(Object of the Invention) An object of the present invention is to provide a method for producing a highly active aluminum nitride sintered body.

(Structure of the Invention) The present invention uses Ca, 8 as an additive to aluminum nitride powder.
r, Ba, Na, Rb, Cs, Cu, Ag, Mg,
Cd, Hg.

This is a method for producing an aluminum nitride sintered body, which is characterized in that at least one of acetylide compounds of Zn, kl, and Ce is added, mixed, and then fired in a high-pressure nitrogen gas atmosphere of more than 1 atmosphere.

(Detailed explanation of configuration) The present invention will be specifically explained below.

The aluminum nitride raw material powder is of high purity,
For example, 98% or more is preferable, but 95 to 98% can also be used. The average particle size is 10 μm or less,
Ca, 8r, Ba, Na, K, which are additives of the present invention, preferably have a diameter of 2 μm or less.

Rb, Cs, Cu, Ag, Mg, Cd, Hg, Zn, A
The content of the acetylide compound of /, Ce is determined by adding the above acetylide compound in an amount of about 0.02 to 10% by weight, followed by mixing and molding.

In manufacturing method 1 of the present invention, the mechanical pressure when press-molding aluminum nitride powder is 500 kg/cut.
For 2° punching, 9/cIIL2 or higher is better for 10006
What is important in the manufacturing method of the present invention is to sinter the aluminum nitride molded body in a high-pressure nitrogen gas atmosphere higher than 1 atmosphere. Since sintered aluminum nitride sublimates and decomposes in a nitrogen gas atmosphere of 1 atm, a high-density aluminum nitride sintered body cannot be obtained. Furthermore, as the pressure of nitrogen gas increases, the density of the aluminum nitride sintered body increases. The sintering temperature is generally 1500 to 2000°C, but is not particularly limited to this range. Note that some acetylide compounds tend to react actively with oxygen, moisture, etc. Since some substances are explosive, care must be taken in the powder processing process, such as mixing with a non-aqueous solvent such as alcohol, heating and drying in a non-oxidizing atmosphere such as nitrogen gas, and not keeping the powder at too high a temperature. .

Next, the present invention will be specifically explained with reference to Examples.

(Example 1) Aluminum nitride powder with an average particle size of 2 μm was mixed with a total of 2% by weight of various acetylide compounds shown in Table 1.Then, this mixed powder was mixed at 2000 kg/cr at room temperature.
n" pressure was applied to form a molded body. This molded body was placed in a graphite setter and sintered at 1800°C for 2 hours in a high-pressure nitrogen gas atmosphere of 100 atm. As a result, 97.
A high-density aluminum nitride sintered body having a relative density of % or more is obtained.

Table 1 (Example 2) Aluminum nitride molded bodies containing various acetylide compounds shown in Table 1 obtained in the same manner as in Example 1 were placed in a graphite setter and sintered under various conditions shown in Table 2. concluded. As a result, a high-density aluminum nitride sintered body having a relative density of 92 to 99 inches was obtained.

(Example 3) 1% by weight of calcium carbide (CaC) was added to aluminum nitride powder having an average particle size of 3 μm and a purity of 98 cm to obtain a mixed powder. Next, 2000 kg/kg of this mixed powder was prepared at room temperature.
A pressure of cm2 was applied to form a molded product. This molded body is placed in a graphite setter in a high-pressure nitrogen gas atmosphere of 1 atm or more.ζ
The aluminum nitride sintered body was then sintered at 1800°C for 2 hours to obtain an aluminum nitride sintered body. FIG. 1 shows the relationship between the relative density of this aluminum nitride sintered body and nitrogen gas pressure.

By increasing the pressure of nitrogen gas during sintering to greater than 1 atm, the relative density of the aluminum nitride sintered body increased rapidly. When the nitrogen gas pressure was 1 atm, the relative density was as low as 80 -, but especially when the pressure was 1.5 atm or more, a high-density aluminum nitride sintered body with a relative density of 90% or more was obtained.

(Example 4) After adding 1% by weight of calcium carbide to 1 powder of aluminum nitride with an average particle size of 3 μm and a purity of 96 cm,
A pressure of 0 kg/ctt*" was applied to form an aluminum nitride molded body. This molded body was placed in a graphite setter and heated to 1800°C in a high pressure nitrogen gas atmosphere of 300 atm.
, sintered for 2 hours. As a result, a high-density aluminum nitride sintered body having a relative density of 99% was obtained. The aluminum nitride sintered body after sintering has an extremely uniform shape without warping or waviness, and has an average surface roughness of 0.2 μm, so it is of extremely high quality.

It should be noted that the effect of increasing density was hardly diminished under pressures greater than 300 atm. Moreover, at a pressure higher than 300 atmospheres, an ordinary high-pressure furnace ()IIP (hot isostatic press) device is required.

(Example 5) A mixed powder of aluminum nitride powder with an average particle size of 1 μm and a purity of 98 cm and calcium carbide powder was cooled under the conditions shown in Table 3, and a mechanical pressure of 30,001 cg/cIL2 was applied at room temperature to form a compact. And so. Table 3 shows the relative density and thermal conductivity at room temperature of the aluminum nitride sintered body obtained by placing this compact in a graphite setter and sintering it in a high-pressure nitrogen gas atmosphere under the conditions shown in Table 3. Shown below.

By sintering aluminum nitride added with calcium carbide in a high-pressure nitrogen gas atmosphere, it has a relative density of 98 cm or more.
An aluminum nitride sintered body having a thermal conductivity of 100 w/mk or more at room temperature was obtained.

(Effect of the invention) According to the present invention, Ca, Sr, Ba, Na, Rb,
Cs.

A molded body of aluminum nitride powder to which at least one of the acetylide compounds of Cu, Ag, Mg, Cd, Hg, Zn, A/, and Ce is added is placed in a graphite setter and sintered in a high-pressure nitrogen gas atmosphere greater than 1 atmosphere. There is provided a method for producing a high-density aluminum nitride sintered body, which is characterized by None. Further, since aluminum nitride powder, which is a nail powder, does not adhere to the surface of the aluminum nitride sintered body after sintering, an aluminum nitride sintered body with good surface smoothness and dimensional accuracy can be obtained. As a result, it has many industrial advantages, such as a high quality aluminum nitride sintered body with high thermal conductivity that can be obtained at a low cost.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between the relative density of aluminum nitride sintered bodies with nitrogen gas pressure carburizing force during sintering. 60.7.29 Showa year, month, day 1, Indication of the incident 1982 Patent application No. 094026 2, Title of the invention Method for manufacturing aluminum nitride sintered body 3
, Relationship to the case of the person making the amendment Applicant: 5-33-1 Shiba, Minato-ku, Tokyo (423) NEC Corporation Representative: Tadahiro Sekimoto 4, Agent 5: Details of the invention in the specification subject to amendment Explanation Column 6, Contents of Correction (1) "C5C2" in the sample/167 column in Table 1 on page 8 of the specification is corrected to [C82C2J. (2) In the column of sample layer 8 in Table 1 on page 8 of the specification, “Cu
C2" is corrected to r Cu2 C2J. (3) In the column for sample 431 in Table 2 on page 10 of the specification, write “
"C5C2" is corrected to "C52C2". 〆、T″″゛・ − Agent Patent Attorney Uchihara , 1 1, +++I

Claims (1)

[Claims] Ca and 8r as additives to aluminum nitride powder. Ba, Na, Rb, Cs, Cu, Ag, Mg, Cd
, Hg, Zn. A method for producing an aluminum nitride sintered body, which comprises adding at least one type of acetylide compound of A/, Ce, mixing, molding, and then firing in a high-pressure nitrogen gas atmosphere of more than 1 atmosphere.