JPH0329029B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a thermal stress relaxation bonding method for alumina and metal, and in particular, a thermal stress relaxation method for alumina and metal suitable for improving bonding strength and reliability. Joining method.

[Background of the invention]

A method for joining ceramics and metal using Al or Al alloy as insert material was disclosed in Japanese Patent Application Laid-open No. 58-
As described in No. 135180, Al or an Al alloy alone was used as an insert material, and the insert material was heated and pressurized at a temperature at or just below its melting point. However, this method focuses solely on bondability, and does not consider improving bonding strength.

[Purpose of the invention]

An object of the present invention is to provide a method for bonding alumina and metal for thermal stress relaxation, which has high bonding strength and high reliability.

[Summary of the invention]

The present invention provides aluminum between the bonding surfaces of alumina and metal.
Alternatively, use two or more three-layer brazing sheets with Al alloy as the core material and Al-Si alloy as both skin materials, and use Al between the brazing sheets.
Alternatively, by interposing an Al alloy sheet, the temperature of the brazing material Al- While heating at a temperature higher than the solidus line of the Si-based alloy, the brazing sheet and the gap between the brazing sheets are
By applying pressure so that the total thickness of Al or Al alloy becomes 2 mm or more, the joint strength and reliability are improved by relaxing thermal stress.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

Example 1 (Joining of alumina and mild steel using Al insert material) As shown in Figure 1, an alumina ring 2 was placed between a mild steel ring 1, and various thicknesses of various thicknesses were placed on the joint surface of the two.
Al sheet 3 and Al-2%Mn alloy as core material, Al-
A three-layer brazing sheet (thickness 0.16 mm) 4 made of 10%Si-2%Mg alloy as both skin materials is inserted to form an Al alloy insert material 5, and this laminate 6 is placed in a vacuum atmosphere (10 ^{- 4} Torr) and junction temperature 600
℃ and a pressure of 0.5 Kgf/mm ² for 30 minutes, and the pressure was maintained for bonding. When the temperature exceeds 580℃, the Al-10%Si- which is both skin materials of the brazing sheet 4
The 2% Mg alloy melts and easily combines with alumina 2.

On the other hand, on the surface of the mild steel ring 1, a compound layer of Fe and Al is formed and combined. FIG. 2 shows the relationship between the thickness and tensile strength of the Al alloy insert material 5 after the above bonded body is bonded. As the thickness of the Al alloy insert material 5 increases, the thermal stress is relaxed and the tensile strength improves, reaching a constant value of 2.3 Kgf/mm ² at 2 mm or more.
A reliable, high-strength bonded product can be obtained.

The airtightness of the joined body in which the thickness of the Al alloy insert material 5 is 2 mm or more was also confirmed in the He leak test.
It was extremely good at less than 10 ^-8 Torr.l/sec. Figure 3 shows the joining method (curve 1) and a single insert material of Al (curve 2) or Al-Cu alloy (curve 3) described in JP-A-58-135180 as a comparative example at liquidus temperature. The insert material was joined at a temperature 10°C lower than that of 2 mm, and the relationship between the pressurizing force at this time and the insert material thickness after joining is shown. From the figure, the welding temperature of the comparative example is just below the melting point, so plastic deformation is significant even with a pressure of 1 Kgf/mm ² or less, but this joining method is 60°C lower than the melting point of the Al sheet 3, so plastic deformation is considerably suppressed. It can be seen that an Al alloy insert material thickness of 2 mm or more can be easily secured.
The appropriate pressing force is 0.25Kgf/ ^mm2 , which is the limit pressure at which no unbonded parts occur, and the pressure is relatively low in plastic deformation.
It is in the range of Kgf/ ^mm2 . Further, the appropriate heating temperature ranges from 580°C, at which the Al-Si-Mg alloy that is the skin material of the brazing sheet melts, to 630°C, at which plastic deformation is relatively small. Although this example and Example 2 described below are bonded in a vacuum atmosphere,
Bonding is possible even in inert gas or air.

Example 2 (Joining alumina and mild steel using a combination of low thermal expansion material and Al insert material) As shown in Figure 4, as a low thermal expansion material, the thickness
0.5mm Kovar (Fe-29%Ni-17%Co alloy)7
This and mild steel ring 1 were heated in a vacuum atmosphere (10 ^-4 Torr) at a temperature of 900°C and a pressing force of 2.5 kgf/
After diffusion bonding by heating and holding pressure at 2 mm ² for 60 minutes, the same Al alloy insert material 5 as in Example 1 was inserted between the bonding surfaces of Kovar 7 and alumina ring 2, and bonding was performed under the same conditions. The relationship between the thickness of the Al alloy insert material and the tensile strength at this time is shown in FIG. The tensile strength improves as the thickness of the Al alloy insert material increases, and a tensile strength of approximately 4 Kgf/mm ² is obtained at 2 mm or more, which is even higher than the Al alloy insert material alone shown in Figure 1. A zygote is obtained. This shows that Al can be used in combination with low thermal expansion materials.
It can be seen that reliable, high-strength jointed products can be obtained when the thickness of the alloy insert material is 2 mm or more. In this example, the mild steel ring 1 and Kovar 7 were directly joined without using an insert material, but the same effect was observed even if Kovar was inserted into an Al alloy insert material, and the tensile strength was The value was between the values shown in Figure 5. In this example, Kovar was used as a low thermal expansion material, but other materials with lower thermal expansion than the metal to be welded may also be used, such as 42Ni (Fe-42%Ni alloy), Ti, W, Mo, and cemented carbide. Effects can be obtained.

In addition, in the embodiments of FIGS. 1 and 4,
One Al sheet 3 is interposed at each joint, but an Al alloy insert material made by alternately stacking several Al sheets and brazing sheets may also be interposed.

〔Effect of the invention〕

As explained above, according to the present invention, in joining alumina and metal, the strength of the joint and the reliability of the joint can be improved by setting the thickness of the insert material after joining the Al alloy to 2 mm or more. A smooth joining method is obtained.

[Brief explanation of drawings]

Figures 1 to 5 are explanatory diagrams of the joining method of the present invention, Figure 1 is an explanatory diagram of the joining method of alumina and mild steel using Al alloy insert material, and Figure 2 is the thickness of the Al insert material of the joined body shown in Figure 1. Figure 3 is a diagram showing the relationship between pressing force and Al insert material thickness for the present method and the conventional method. Figure 4 shows the relationship between alumina and mild steel using a combination of low thermal expansion material and Al insert material. An explanatory diagram of the joining method, FIG. 5 is a diagram showing the relationship between the thickness of the Al insert material and the tensile strength of the joined body shown in FIG. 1... Mild steel ring, 2... Alumina ring, 3
...Al sheet, 4...Al-Si-Mg brazing sheet, 7... Kovar sheet.

Claims (1)

[Claims] 1. In a thermal stress relaxation bonding method for alumina and metal, a three-layer structure in which Al or Al alloy is used as a core material and Al-Si alloy is used as both skin materials between the bonding surfaces of alumina and metal. Using a brazing sheet made of
The three-layer brazing sheet is heated at a temperature above the solidus line of the Al-Si alloy and below the melting point of the core material Al, or below the solidus line of the Al alloy.
Al is used between the brazing sheets.
Or insert an Al alloy sheet so that the total thickness of these inserts is 2 mm or more.
A thermal stress relaxation bonding method for alumina and metal characterized by applying pressure. 2. The thermal stress relaxation bonding method according to claim 1, characterized in that the heating temperature is 580°C to 630°C and the pressing force is 0.25Kgf/mm ² to 1Kgf/mm ² . thermal stress relaxation bonding method.