JPS59174582A - Method of bonding ceramics to metal - 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 The present invention relates to an improvement in a method for joining metals and ceramics.

In recent years, ceramics have come to be widely used in electronic components and vacuum equipment, and therefore various studies are being conducted on bonding techniques between ceramics and metals.

As a typical method, for example, the surface of ceramics is
There is a method of processing by o-Mn method and brazing metal to this. To explain this with reference to Figure 1, the size is 3.
Add Mn powder of 3 μm or less to Mo powder of 15 μm or less.
A glassy intermediate layer 2 is formed by mixing 20% of the mixture, adding an organic binder, kneading it, applying it to the surface of the ceramic 1, and baking it at 1300 to 1500°C in a hydrogen stream containing water vapor. Next, this surface is coated with Ni plating 3 to improve wettability, and then brazed to a mating metal 5 in a hydrogen stream with a suitable material 4 in between.

As described above, ceramics generally have poor wettability with metal, so they cannot be directly brazed to metals, and brazing requires an intermediate layer, which is time-consuming and requires skill.

Also, if you braze with a low melting point wax, if the temperature rises during use, the solder will come off and the joint will separate.
There are problems such as wax volatilization and poor vacuum quality.

The purpose of the present invention is to provide a method for directly bonding metal to ceramic nox, which solves the above-mentioned problems.
A method for joining metal and ceramics, characterized by stacking the metal and ceramics, placing an oxidized layer of the metal between them, and holding the metal under pressure at a temperature below the melting point of the metal in a vacuum or inert gas atmosphere. It relates to a method of joining metal and ceramics.

The present inventor has conducted various studies on pressure welding of metals, and attempted to apply this knowledge to the joining of ceramics and metals. For example, by heating copper and alumina in a high vacuum or in a high purity argon gas atmosphere. I tried applying pressure while
It did not bond at any temperature. However, when air was mixed in this atmosphere and heated in the atmosphere, it was found that the two bonded well and the joint strength was high.

Next, a mode of carrying out the present invention using the apparatus shown in FIG. 2 will be explained by taking as an example the bonding of copper and alumina.

Alumina 11 was ADS-11 with a purity of 99.0% as a test material.
20 10 circles x 10 dragon length, copper 12 is oxygen-free copper (purity 99
．． 98%), and the heating furnace 13 is connected to the inert gas supply pipe 1.
4 to 1 argon gas (purity 99.97%) is blown in to create an argon gas atmosphere, heated in that atmosphere, and when each specified temperature shown in Table 1 is reached, air is introduced into the furnace and the copper surface is heated. Oxidize and simultaneously apply O, I kgf/
After applying a force of 2 mm 2 and holding it for 10 minutes, the pressurization was stopped, and the inside of the furnace was again made into a high-purity argon gas atmosphere and the furnace was cooled.

It was found that bonding was possible at a heating temperature of 900° C. or higher, and the shear strength of the bonded portion increased as the heating temperature rose, as shown in Table 1.

Regarding the oxygen concentration in the heating atmosphere, no bonding occurred at any temperature when heating was performed in a vacuum or in a high purity argon gas atmosphere from which oxygen in the argon gas had been removed. During pressurization, air was mixed with argon gas to change the oxygen concentration to a range of 0 to 21%, and the temperature was 1030℃ and 0.1kgf.
/ Forehead 2. When pressurized while oxidizing for 10 minutes, the shear strength of the joint is 3 to 8 kgf 7m, except when the oxygen concentration is 0.
Met. Bonding did not occur with oxygen O, and bonding was possible at about 0.2 ppm, but the joint strength varied. When the oxygen concentration is set to 3% or more, complete bonding occurs and there is no significant difference in joint strength, so it is judged that only a small amount of copper oxide is required for bonding.

Line analysis of elements near the bonding surface using an X-ray microanalyzer revealed that the atoms had moved several microns, but the bonding mechanism is not clear.

Cu203 and CuO were observed as oxides on the surface of copper.

An example of the microscopic structure of the joint is shown in FIG. 2, and in this case, the thickness of the oxide layer on the copper surface was about 30 μm.

Regarding the effect of pressurization, 1 in an argon gas atmosphere.
When bonding was performed by oxidizing at 030° C. for 10 minutes, it was confirmed that bonding did not occur under pressure O, but bonding occurred when pressure was applied. Even if the pressing force is increased, the deformation of the copper only increases, and there is almost no change in the strength of the joint. 0 at 1000℃.
2 kgf/tm" is sufficient and the size is sufficient as long as it is necessary to bring the bonding surfaces of metal and ceramic into close contact.

Regarding preliminary oxidation, in the present invention, the surface of the metal to be bonded is oxidized during pressurization, and it is necessary to pressurize with the oxidized metal layer interposed between the metal and the ceramic. The metal oxide layer may be formed during pressurization at a predetermined temperature as in the above experiment, or may be formed before pressurization. Alternatively, a metal whose surface has been oxidized in advance using a separate furnace may be used.

As a means of forming the metal oxide layer before pressurization, for example, when heating from a temperature of about 100 to 100, the metal surface is oxidized by heating in air up to a temperature in the middle of heating, and then heating in an argon gas atmosphere at higher temperatures. Pressure may be applied at a pressurizing temperature to stop the formation of oxides.

An example of this is to oxidize the copper surface by heating in air from a temperature of 485°C, then replace the atmosphere in the furnace with argon gas, and heat it at 1060°C, 0.1kgf/f12,
The shear strength is 14.4 kgf when bonded for 10 minutes.
/It was part 2.

The above was explained using the example of joining copper and alumina, but copper alloy (commercially available chromium-copper alloy) and mullite (silicon oxide 52
%, alumina 42%) in air up to 600°C, and above 600°C, the atmosphere in the furnace was replaced with argon gas and heating continued, and at 1060°C, 0.2 kg f /
As we were able to obtain a joint with sufficient shear strength by applying a force of vm 2 for 20 minutes and then cooling it, in addition to the joining of general metals and ceramics, for example, copper and alumina, we also applied aluminum as a metal. This method can also be applied to the joining of such alloys, iron and its alloys, etc., and ceramics such as mullite, silicon carbide, silicon nitride, etc.

Alternatively, when joining alumina to each other, a thin layer of copper oxide is formed on the surface of the copper using the method of the present invention, and alumina can be easily joined to each other by sandwiching copper between them. Its range of applications is wide, as it can be used to bond metals with appropriate thin metal layers in between.

As described above, the method of the present invention differs from conventional methods in joining metals and ceramics by interposing a thin layer of metal oxide and directly joining them with a single heating operation with a simple operation. I can do it. Since it is a direct bond, there is no need for expensive solder, and the strength of the joint is high. Furthermore, since no solder is used, there is no risk of the solder melting and the bonded parts coming off, and there is no volatilization of the low melting point brazing material, so it is highly effective when applied to high vacuum equipment parts.

In addition, once the bonding conditions are determined, the bonding method can be bonded using a certain heating method, so no special skill is required, and its practical effects are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a conventional bonding method, FIG. 2 is an elevational view schematically showing an example of an apparatus suitable for carrying out the method of the present invention, and FIG. 3 is a cross-sectional view showing an example of a conventional joining method. It is a photograph (X100) showing the microscopic structure near the bonding surface between aluminum and alumina. 11... Alumina, 12... Copper, 13... Heating furnace, 17... Copper oxide thin layer

Claims (1)

[Claims] J. A method for joining a metal and a ceramic, in which the metal and the ceramic are stacked, an oxide layer of the metal is placed between them, and the temperature is below the melting point of the metal in a vacuum or an inert gas atmosphere. 2. A method of joining metal and ceramics characterized by holding the metal under pressure at a temperature of Method 3 for joining metal and ceramics according to scope 1, a patent claim in which the oxidized layer of the metal is a thin layer of oxide formed on the metal held in an air or oxygen-containing gas atmosphere at a pressurized temperature. A method for joining metals and ceramics as described in item 1 of the scope of