JPS62246866A - 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 Field of Application) The present invention relates to a method for manufacturing a high-density, sacrificial conductive aluminum nitride sintered body.

(Prior Art) Substrates made of aluminum nitride sintered bodies are attracting attention as substrates for ICs, LSIs, etc., and as heat sinks for thyristors.

Aluminum nitride itself can be produced using a direct nitriding method in which aluminum is heat-treated at 1300 to 1500°C in a nitrogen atmosphere;
Carbon powder is mixed with Al2O3, and this is heated in a nitrogen atmosphere for 1
It can be synthesized by a reductive nitriding method that involves heat treatment at 400 to 1,700°C.

In obtaining this sintered body of aluminum nitride, it was difficult to sinter the aluminum nitride itself under normal pressure and make it compact to the theoretical density.

Therefore, research into sintered bodies based on aluminum nitride additives has been carried out, and for example, in Japanese Patent Publication No. 8655/1986, a starting material mainly consisting of a mixed powder of 1 cum aluminum nitride and yttrium oxide has been developed. The molded product was molded under nitrogen or an inert atmosphere for 150 min.
A method of pressure sintering at 0 to 2200°C has been proposed.

In addition, in Japanese Patent Publication No. 46-41003, a mixed powder of aluminum nitride, yttrium oxide, and aluminum metal is mixed with a binder and formed into a compact by pressure molding.
This molded body is pre-prepared (a) in a nitrogen or ammonia atmosphere.
A method of main firing at 1400 to 2200°C has been proposed.

These proposals were culminated in the addition of alkaline earth metal oxides or rare earth intoxicants to aluminum nitride, and aluminum nitride was evaluated as a material that could be used as a dense and highly thermally conductive sintered body. It is something that can be used.

(Problem to be solved by the invention) In reality, alkaline earth metals or rare earth metals as sintering aids are added to aluminum nitride powder in the form of oxides or carbonates, but the dispersibility is poor. It was not as good as expected, and different phases were generated during sintering, which resulted in a decrease in thermal conductivity. Further, there were other problems such as the high sintering temperature required to form a sintered body and the fact that the density could not be increased unless the amount added was increased.

(Objective of the Invention) Therefore, an object of the present invention is to provide a method for mounting an aluminum nitride sintered body that can be sintered at low temperatures, exhibits a high density and good thermal conductivity.

(Structure of the Invention) According to the present invention, aluminum nitride powder obtained in advance by a direct nitriding method, a binary nitriding method, or the like is used.

The surface of this aluminum nitride powder is coated with a solution in which healthy compounds of alkaline earth, rare earth, titanium, and aluminum are dissolved by spraying, dipping, or the like. The aluminum nitride powder coated with each of the above organic compounds is heat treated in air or in an inert atmosphere. Next, an aluminum nitride sintered body can be obtained by molding this aluminum nitride powder and sintering the molded body in a nitrogen or inert atmosphere.

alkaline earth coating the surface of aluminum nitride powder,
Compounds of rare earths, titanium, and aluminum include:
Barium stearate, calcium stearate, titanium alkoxide, yttrium alkoxide, erbium alkoxide, yttrium acetylacetonate, etc., and metal chelate compounds such as ethyl-diamine, glycine, diethylenetriamine, N-phenylhydro[]xylamine dithizone derivatives, etc. It can be either solid or liquid, and if it is solid, it is used by dissolving it in a solvent.

The amount of each of the above organic compounds relative to aluminum nitride is preferably in the range of 0.1 to 3.0% by weight in terms of oxide.

This is because if it is less than 0.1% by weight, no improvement in relative density or thermal conductivity will be seen, while if it exceeds 3.0% by weight, the thermal conductivity will drop significantly.

(Function) According to the method of the present invention, the surface of the aluminum nitride powder is coated with alkaline earth, rare earth, titanium, and alkali, and the aluminum nitride powder in such a state is molded and this molded body is formed. An aluminum nitride sintered body can be obtained by sintering.

(Effects) Since aluminum nitride powder is coated with alkaline earth, rare earth, titanium, and aluminum, reducing the amount itself will reduce the original properties of aluminum nitride. As a result, thermal conductivity can be increased. Since it has excellent dispersibility, it is possible to lower the sintering temperature to 1700° C. or lower.

(Example) The present invention will be explained in detail below according to examples.

Example 1゜'? shown in Table 1. Five types of organic compounds were added and mixed in an amount of 1.0 weight ff1% based on aluminum nitride in terms of oxides, and then heat-treated at 150° C. with stirring.

Then at 600-800°C in an inert atmosphere such as nitrogen.
The mixture was heated at a temperature of 1 hour. To the obtained powder, 7% by weight of baraf and carbon were added as a binder, and the powder was molded into a size of 10.0 mm x 3.0 mm at a pressure of 5.0 g/am2. This molded body was heated at 600°C for 2 hours in a nitrogen atmosphere.
After being degreased by heat treatment for two hours, it was sintered in a nitrogen atmosphere at 650° C. for two hours.

When the relative density and thermal conductivity of each sintered body were measured, the values shown in Table 1 were obtained.

Table 1 From Table 1, when sintered at 1650°C, all 9
A sintered body of aluminum nitride having a relative density value of 8% or more and high thermal conductivity has been obtained.

Example 2 Barium stearate was added to aluminum nitride powder in the proportions shown in Table 2 and mixed, followed by heat treatment at 150° C. with stirring.

Next, heat treatment was performed at a temperature of 600 to 800°C in an inert atmosphere such as nitrogen, and at 600°C in a natural atmosphere.

Thus obtained r: To the powder was added 7% by weight of paraffin as a binder, and this powder was reduced to 5.0 g/cI1
10.0mm x 3.0mm at a pressure of 12. It was molded to a size of 0mm.

This molded body was sintered at 1650° C. for 2 hours in a nitrogen atmosphere.

When the relative density and thermal conductivity of the sintered body were measured,
The values shown in Table 2 were shown.

In addition, sample numbers 2-1.2-6 marked with * in Table 2
is outside the scope of this invention.

From Table 2, it is clear that all of them showed relative density values of 98.0% or more, and had high thermal conductivity.

In addition to the above examples, it was confirmed that similar effects could be obtained with other organic compounds of alkaline earth metals, rare earth metals, titanium, and aluminum.

Claims (1)

[Claims] (1) The surface of aluminum nitride powder is coated with a solution containing organic compounds of alkaline earth, rare earth, titanium, and aluminum, heat-treated in air or in an inert atmosphere, and the heat-treated aluminum nitride powder is molded. A method for producing an aluminum nitride sintered body, comprising sintering a molded body in a nitrogen or inert atmosphere.