JPH0511070B2 - - Google Patents

Description

[Detailed description of the invention]

[Object of the Invention] (Industrial Application Field) The present invention relates to an aluminum nitride sintered body, and more specifically, a conductive metallized layer having good high-temperature adhesion to the aluminum nitride sintered body base material,
Furthermore, the present invention relates to an aluminum nitride sintered body in which the conductive metallized layer can be formed at a lower temperature than before. (Conventional technology) Aluminum nitride (AlN) sintered bodies have insulating properties,
It has excellent corrosion resistance and thermal shock resistance, high high temperature strength, and high thermal conductivity.
It is used as a material for various structural materials, various electronic and electrical parts, etc., and especially in recent years, it is used as a semiconductor substrate to replace alumina (Al ₂ O ₃ ), which does not have sufficient heat dissipation properties, and beryllia (BeO), which is difficult to handle due to its toxicity. It is attracting attention as a material for By the way, no matter what purpose an AlN sintered body is used for, there is often a need to join this sintered body to some kind of metal member, and in that case,
It is common practice to form a conductive metallized layer on the surface of an AlN sintered body. As a metallization method for such an AlN sintered body, after forming an oxide layer (Al ₂ O ₃ ) on the surface of the sintered body,
Known methods include the direct bond cutter method (DBC method) that directly bonds copper (Cu) foil, and the thick film method that uses copper (Cu), gold (Au), silver (Ag)-palladium (Pd), etc. There is. However, the conductive metallized layer formed on the surface of the AlN sintered body by applying the above method has poor adhesion to the AlN sintered body, especially at high temperatures.
It is difficult to join other parts by applying a joining method that is performed at temperatures above about 30°F, and even if it were possible to join them, it is difficult to use the AlN sintered body with other parts joined at high temperatures. When this happens, the metallized layer peels off from the surface of the sintered body, resulting in the problem of other components falling off. In particular, with such a conductive metallized layer
When an AlN sintered body is used as a heat dissipation substrate for electronic circuits, this substrate is subjected to temperature changes (thermal cycles) from low to high temperatures and from high to low temperatures, and the constituent components of the metallized layer and AlN
There is an inconvenience that cracks occur in the metallized layer due to the difference in thermal expansion coefficient between the metallized layer and the metallized layer. In order to solve this problem, the present applicant has already provided a conductive metallized layer containing one or more selected from molybdenum, tungsten, and tantalum, and a group element or a group a element as constituent elements of the constituent phase. We have proposed an AlN sintered body (see the specification of Japanese Patent Application No. 33826/1983). The conductive metallized layer of this AlN sintered body is extremely superior in that it has high bonding strength to the base AlN sintered body even at high temperatures and in a reducing atmosphere. It is something that exists. however,
The conductive metallized layer possessed by such an AlN sintered body requires a special heating furnace because it is necessary to metalize it at a relatively high temperature (1700 to 1800°C) depending on the constituent elements of its constituent phase. Furthermore, warping may occur in the AlN sintered body that serves as the base material during metallization, and if left as is, the product will be defective. Therefore, in such cases, usually
This method is still insufficient in that it is necessary to perform a step to re-warp the base material after metallization, and there is still room for further improvement. (Problems to be solved by the invention) In the case of a conventional AlN sintered body having a conductive metallized layer, the metallized layer and the base material
If the bonding strength with the AlN sintered body is weak or if the metallized layer is formed at high temperatures (1700 to 1800°C), the AlN sintered body that is the base material may warp, and as a result, There are problems in that the product may be defective or that a further warping process must be provided. Moreover, since metallization is carried out at a high temperature of 1700°C or higher, it cannot be processed using an industrial furnace, especially a continuous heating furnace, which is usually designed with a heating range of 1600°C or lower. Therefore, the present invention provides a conductive metallized layer and
The bonding strength with the AlN sintered base material is high, and 1600
Since metallization can be performed at a relatively low temperature below ℃, it can be used on industrial production lines, and the base material does not warp.
The purpose is to provide AlN sintered bodies. [Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present inventors have developed a method that does not reduce the bonding strength between the base material and the conductive metallized layer, and that can be performed at a relatively low temperature. As a result of studying the combination of component elements of the constituent phases of the conductive metallized layer that would allow metallization without causing warping of the base material, the present invention was completed. The aluminum nitride sintered body of the present invention is an aluminum nitride sintered body having a conductive metallized phase on at least a part of its surface, wherein the conductive metallized phase is (a) one or two selected from molybdenum and tungsten. (b) Nitride of one or more elements selected from group a elements of the periodic table; and (c) One or two elements selected from cobalt and nickel. It is characterized by containing a single substance as a component of a constituent layer. As described above, the AlN sintered body of the present invention is characterized by the combination of constituent elements of the constituent phases of the conductive metallized layer formed on the surface of the sintered base material, and the physical properties of the AlN sintered body itself are Although there are no particular restrictions on the thermal conductivity, it is preferable that the thermal conductivity is 50 w/m·k or more, for example, from the viewpoint of applications such as semiconductor substrates. It is a component element of the constituent phase of the conductive metallized layer.
Elements in group (a), namely molybdenum (Mo) and tungsten (W), have excellent heat resistance and
It has a thermal expansion coefficient almost similar to that of the AlN sintered body base material, and is a single component that contributes to improving the heat resistance and heat cycle resistance of the metallized layer. Also, elements in group (b), namely titanium (Ti), which is a group a element of the periodic table,
Zirconium (Zr) and hafnium (Hf) nitrides are components of compounds that provide a strong bond between the conductive metallized layer and the AlN sintered base material, and also contribute to imparting conductivity to the metallized layer. It is. Also, elements of group (c), namely cobalt (Co),
Nickel (Ni) is a single component that contributes to lowering the heating temperature when forming a conductive metallized layer. In the present invention, the composition ratio of the elements of the group (a), the elements of the group (b), and the elements of the group (c), which are component elements of the constituent phase of the conductive metallized layer of the aluminum nitride sintered body. is not particularly limited and is appropriately determined depending on the type and combination of elements used, but for example, preferably 1 to 20% by weight of the synthesized weight of elements belonging to group (c) in the whole. , more preferably set at 5 to 15% by weight. In this case, if the amount of elements belonging to group (c) is too small, the temperature during metallization cannot be lowered to a level that does not adversely affect the AlN sintered body base material, and the amount of If it is too high, problems such as a decrease in the bonding strength between the AlN sintered body base material and the conductive metallized layer will occur. The AlN sintered body of the present invention is manufactured, for example, as follows. That is, first, the
A simple substance of an element selected from group (a) above, a nitride of an element selected from group (b), an element selected from group (c) on a desired surface of the AlN sintered base material. Apply a paste or liquid containing each of the following elements. Specifically, this paste or liquid material is obtained by dispersing the above element or compound powder in a binder such as ethyl cellulose or nitrocellulose. Further, it is desirable that the paste or liquid contains at least 5% by weight of the elements selected from the group (c) above. Next, as described above, a paste or liquid material is applied to the surface of the AlN sintered body base material, dried, and then heat treated to form a metallized layer. The heating temperature at this time varies depending on the type and combination of component elements, but usually about 1500 to 1600°C is sufficient. Further, as the atmospheric gas, nitrogen gas, dry homing gas, wet homing gas, etc. can be used, and the processing time is preferably set to about 0.5 to 2 hours. Furthermore, when joining other parts to the AlN sintered body having the conductive metallized layer obtained in this way, the conductive metallized layer is first plated with Ni or the like, and then, in a homing gas,
The plating layer may be annealed at 600 to 850°C, and then brazed or soldered. The AlN sintered body of the present invention can be applied as a constituent material for highly integrated and high-output electronic circuit boards, igniters, high-frequency transistors, laser tubes, magnetrons, or various heaters. (Example) Example 1 A raw material paste was prepared by mixing 5 parts by weight of ethyl cellulose with 100 parts by weight of a mixture of W powder, titanium nitride (TiN) powder, and cobalt powder in a weight ratio of 79:18:9. was manufactured. Next, the paste was applied to the surfaces of a total of 100 AlN sintered base materials obtained by sintering with the addition of 3% by weight of yttrium (Y ₂ O ₃ ). Thereafter, the applied paste was dried and then heated at 1600° C. for 1 hour in a nitrogen gas atmosphere furnace to form a conductive metallized layer. As a result, no warpage was observed in any of the AlN sintered base materials. Next, in order to evaluate the bonding strength of this conductive metallized layer to the AlN sintered base material, the metallized layer was plated with Ni and annealed at about 800°C in a homing gas. The tip of the wire made of (Co-Fe alloy) was brazed. When the bonding strength (Kg/mm ² ) was measured by pulling the wire in a direction perpendicular to the metallized surface, it was 2Kg/mm ² or more. Comparative example Molybdenum (Mo) powder and titanium nitride (TiN)
Weight ratio of powder and ethyl cellulose is 8:2:1
Prepare a raw material paste by mixing with
The coating was applied to the surfaces of a total of 100 AlN sintered base materials containing 3% by weight of Y ₂ O ₃ . After drying this,
A conductive metallized layer was formed by heating at about 1800° C. for 1 hour in N ₂ gas. As a result, two out of a total of 100 base materials were slightly warped. Next, the bonding strength of the conductive metallized layer to the AlN sintered base material was measured in the same manner as in Example 1, and was found to be 2 Kg/mm ² or more. Examples 2 to 12 Elements selected from the above groups (a), (b) and (c) ((a) and (c) are simple substances, (b) is a nitride) binder and metallization conditions A conductive metallized layer was formed in the same manner as in Example 1 except as shown in the table.
An AlN sintered body was manufactured. As a result, no warpage was observed in the sintered body. In addition, the bonding strength between the conductive metallized layer and the AlN sintered base material was measured in Example 1.
Measurements were made in the same manner as above, and the results are shown in the table.

[Table] Note: All metallization conditions are heating in a nitrogen gas atmosphere furnace for 1 hour.
As is clear from the table, the AlN sintered body of the present invention had a conductive metallized layer that had high bonding strength with the AlN sintered body base material even after the soldering and brazing steps. [Effects of the Invention] As explained above, in the AlN sintered body of the present invention, AlN
The sintered body base material did not warp at all.
Therefore, the defect rate of the product is reduced, and there is no need to provide a separate process for straightening the product, and as a result, metallization using a continuous furnace becomes possible.

Claims (1)

[Claims] 1. An aluminum nitride sintered body having a conductive metallized phase on at least a part of its surface,
The conductive metallized phase is (a) a simple substance of one or two elements selected from molybdenum and tungsten; (b) nitridation of one or more elements selected from group a elements of the periodic table; and (c) an aluminum nitride sintered body, characterized in that it contains one or two elements selected from cobalt and nickel as constituent phase components. 2. The aluminum nitride sintered body according to claim 1, wherein the aluminum nitride sintered body is a semiconductor substrate.