JPH0684058B2 - Method for metallizing ceramics and alloy foil for metallizing ceramics - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for metallizing ceramics and an alloy foil for metallizing ceramics.

[Technical background of the invention and its problems]

Recently, ceramic materials have begun to be used in a wide range of fields such as structural materials and functional materials due to their excellent characteristics. In many cases, parts are made of ceramics alone, but in order to utilize ceramics in more fields, it is necessary to be able to bond with metals. For this reason,
There is a demand for establishment of metallizing to ceramics.

By the way, conventionally, the following method is known as a method for metallizing ceramics.

A method in which a powder containing Mo or W as a main component is applied to the surface of a ceramic base material and heated to 1400 to 1700 ° C. in a reducing atmosphere to react with the ceramic base material to perform metallization.

A method of arranging a foil of Au or Pt on the surface of a ceramic base material, heating the foil while applying pressure, and performing metallization.

However, the above method is mainly used for ceramics.
It is intended for Al ₂ O ₃ and cannot be metallized with high adhesion to nitride ceramics such as aluminum nitride, which has recently been attracting attention. Further, in the above method, since an expensive precious metal is used, the economical efficiency is poor and a high pressure is required for the purpose of enhancing the adhesiveness, which is not preferable for metallizing to an electronic component or the like which is liable to be deformed.

Therefore, active metals such as Ti and Zr are Cu, Ni and Fe.
In alloys with transition metals such as Cu, N, the melting point (Ti; 1720 ℃, Zr1860 ℃) of the active metal alone and Cu, N in the eutectic composition region
Focusing on making the melting point several hundreds of degrees Celsius or less compared to the melting points of i and Fe alone (1083 ° C, 1453 ° C, 1534 ° C respectively), after laminating the active metal layer and the transition metal layer on the ceramic base material, A method is known in which heat treatment is performed at a temperature higher than the melting point of an alloy of these metals so that atoms of the transition metal and the active metal are mutually diffused to form an alloy, and metallization is performed. According to such a method, since the surface of the ceramic base material is sufficiently leaked by the synergistic liquid of the transition metal and the active metal, almost no pressurization is required, and the effect of the active metal causes a strong adhesion to the ceramic base material. You can metalize with. However, there is a problem that cracks occur in the ceramic base material after the metallizing is performed in this manner.

[Object of the Invention]

The present invention is intended to provide a metallizing method capable of strongly metallizing a ceramic base material without pressurizing it, and further capable of preventing the occurrence of cracks in the ceramic base material after metallizing, and an alloy foil used in such a method. Is.

[Outline of Invention]

The present inventors have developed the metallizing method of the present invention and the alloy foil used for it, paying attention to the following points. That is, in the metallizing method of forming a metal layer on the surface of the ceramic by taking advantage of the good leak property between the active metal and the ceramic, the cause of the crack in the ceramic base material after the formation of the metal layer is thermal stress. It was clarified that the factors controlling the temperature were the molding temperature and the thickness of the metal layer. Based on this fact, when expressing the stress σ generated in ceramics by a mathematical formula, Becomes Here, Δα: difference in coefficient of thermal expansion between ceramics and metal, ΔT: temperature difference between molding temperature and room temperature, E: Young's modulus, t:
Thickness, c and m represent ceramics and metal, respectively. Substituting various values into this equation, for example, when Cu is formed on AlN at a thickness of 0.5 mm and at 1000 ° C, Δα = 8 × 10 ^-6 / ° C, ΔT = 975
^{℃, Ec = 30,000kg / mm 2} , Em = 11,600Kg / mm 2, tc = 3mm tm =
From 0.5 mm, σ = 121.6 kg / mm ² can be obtained. A crack occurs when this value occurs in an extremely thin portion of the ceramic surface. In fact, all of the above equations are calculated as elastic deformation, so the stress relaxation effect of Cu at high temperature must be taken into consideration, but in any case, when the metal layer is thick, cracks occur in the ceramics. Stress is easily generated.

Therefore, the inventors of the present invention have conducted intensive studies based on the above-mentioned investigation results, and found that an alloy layer of a transition metal and an active metal having a thickness of 30 μm or less is arranged on the surface of the ceramic base material and heated to a temperature equal to or higher than the melting point of the alloy. Have found a method that can firmly metalize the ceramic base material without causing cracks. Further, it has been found that an alloy foil composed of a transition metal and an active metal and having a thickness of 30 μm or less can be effectively used for the above metalizing.

That is, the method of metallizing ceramics according to the present invention uses Cu, Ni, Fe and Co on the surface of the ceramic base material.
After arranging an alloy layer having a thickness of 30 μm or less made of a transition metal and an active metal selected from at least one selected from the group, the ceramic base material is heated to a temperature equal to or higher than the melting point of the alloy. Is.

Further, the alloy foil for metallizing ceramics according to the present invention is at least one of the group of Cu, Ni, Fe and Co.
It is characterized in that it is composed of a transition metal selected from species and an active metal and has a thickness of 30 μm or less.

Various ceramics such as nitrides (AlN, Si ₃ N ₄ , BN, etc.), carbides (SiC, etc.), oxides (Al ₂ O _3, etc.) can be used as the ceramics.

Examples of the active metal include Ti, Zr, Y, Hf and the like.

The alloy layer contains an active metal that enhances the adhesion strength to the ceramic base material, and has a lower melting temperature than that of the active metal alone, so that it can be industrially implemented easily. The composition ratio of such an alloy layer cannot be generally limited depending on the types of the transition metal and active metal which are the components, but it is desirable to set the composition at or near the eutectic point from the viewpoint of lowering the melting temperature. The reason for limiting the thickness of the alloy layer as described above is that if the thickness exceeds 30 μm, cracks occur in the ceramic base material after metallizing. Further, as the alloy layer, specifically, (a)
The transition metal and the active metal listed in the second invention of the present application,
An alloy foil having a thickness of 30 μm or less, or a form of an alloy layer deposited on the surface of the (b) ceramic base material by a sputtering method, a plasma spraying method, or the like is used. If necessary, a melting point depressing element may be added to the alloy.

The atmosphere at the time of the above heat treatment is arbitrary in the air, in a non-oxidizing gas such as argon gas, and is not particularly limited.

Example of Invention

 Next, examples of the present invention will be described.

Example 1 First, a width of 25 m was obtained from a Cu-28 wt% Ti alloy by a liquid quenching method.
A Cu-Ti alloy foil strip having a thickness of m and a thickness of 25 μm was formed. Continuing,
This foil strip is cut into Cu with a width of 25 mm, a length of 50 mm and a thickness of 25 μm.
-Ti alloy foil was placed on one side of the Si ₃ N ₄ square bar. Next, the alloy foil was heated to 930 ° C. in an argon atmosphere to melt it, and then cooled to form a metalizing layer having a thickness of 25 μm on the surface of the Si ₃ N ₄ square bar.

Except placing the Comparative Example Cu-Ti alloy foil 2 ply with Si ₃ N ₄ square timber, to form a 50μm thick metallization layer of the Si ₃ N ₄ square timber surface in the same manner as in Example 1.

Then, when the cross section of the Si ₃ N ₄ square bar including the metallizing layer of Example 1 and the comparative example was observed, it was found that the metallizing layer and the Si ₃ N ₄ square bar were well bonded to each other. However, in the case of the comparative example, many cracks were observed inside the Si ₃ N ₄ square. On the other hand, in the case of Example 1, Si ₃ N _{4 was used.}
No cracks were generated inside the square bar.

Example 2 On the top surface of a 25 ^mmφ AlN cylindrical body, a thickness of 2 according to the surface shape 2
A Cu-28 wt% Ti alloy foil of 5 μm was placed and heated to 925 ° C. under a vacuum of 4 × 10 ⁻⁵ torr, the alloy foil was melted, held for 3 minutes, and then cooled to form an AlN cylinder. A 25 μm thick metallizing layer was formed on the top surface of the.

Then, when the cross section of the AlN cylinder containing the metallizing layer of Example 2 was observed, no cracking of the AlN cylinder was observed. Moreover, when such an AlN columnar body was joined to the AlN member of the electro part via the metalizing layer, it was possible to easily and firmly join.

〔The invention's effect〕

As described above in detail, according to the present invention, it is possible to strongly metallize the ceramic base material without applying pressure to the ceramic base material, and further, to prevent the occurrence of cracks in the ceramic base material after the metallizing, and the metallizing method, which is effective for such a method. An alloy foil that can be used for

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hiromitsu Takeda Inventor Hiromitsu Takeda 1 Komukai-shi, Kawasaki-shi, Kanagawa Higashi Koshibaura Electric Co., Ltd. Research Institute (72) Inventor Tatsuo Yamazaki Komukai, Kawasaki-shi, Kanagawa 1st location, Toshiba Koshiba Electric Co., Ltd. (72) Inventor, Makoto Shirakane 1st location, Komukai Toshibacho, Kouki-ku, Kawasaki, Kanagawa Higashi Koshiba Electric Co., Ltd. (56) References 52-19137 (JP, A)

Claims (4)

[Claims] 1. A synthetic layer having a thickness of 30 μm or less made of a transition metal and an active metal selected from the group consisting of Cu, Ni, Fe and Co is arranged on the surface of a ceramic base material, A method of metallizing ceramics, comprising heating a ceramic base material to a temperature equal to or higher than the melting point of the alloy. 2. The ceramic metallizing method according to claim 1, wherein the active metal is any one of Ti, Zr, Y and Hf. 3. A ceramics metallizing material comprising a transition metal and an active metal selected from at least one selected from the group consisting of Cu, Ni, Fe and Co, and having a thickness of 30 μm or less. Alloy foil. 4. The alloy metallizing foil for ceramics according to claim 3, wherein the active metal is any one of Ti, Zr, Y and Hf.