JP2629915B2 - Dissimilar metal materials joining method - Google Patents

Description

The present invention relates to the joining of articles manufactured by joining a plurality of dissimilar metal materials in a fitted state, such as a backing plate used in a magnetron sputtering apparatus. The present invention relates to a method, and more particularly to an improvement for improving the soundness of a joint.

"Prior art" For example, as a backing plate to be attached to a sputtering electrode of a magnetron sputtering apparatus, recently, as shown in FIG. 8, a composite type in which a plurality of dissimilar metal materials are combined to improve magnetic permeability and thermal conductivity. Backing plates have been developed.

By the way, when manufacturing this type of composite backing plate, so far, Japanese Patent Application No. 61-181774.
As shown in FIG. 9, each member is molded and fitted to a size that causes a very small gap therebetween, and the fitting portion P is brazed all around as shown in FIG. Alternatively, a fusion welding method has been adopted.

[Problems to be Solved by the Invention] However, in the case of the backing plate manufactured by the above-described joining method, cracks may occur in the joint P immediately after welding or brazing is completed. Also, even if cracks do not occur at this point, when the backing plate is mounted on the sputter electrode and used, fatigue cracks occur in the joint P due to the cooling water pressure during use, and the cooling water is In some cases, problems such as leakage into the inside were caused.

Then, the present inventors examined the cause of the crack in detail, and as a result, in the above-mentioned joining method, in the cooling process after welding each member, each member was contracted as shown by an arrow in FIG. A new finding has been obtained that a tensile stress is generated at the joint P, causing a crack at the joint P.

The present invention has been made in view of the above-mentioned problems of the related art. Even if each member is cooled after brazing or welding, a tensile stress is not applied to a joint, and a joint attributable to the stress is not applied. It is an object of the present invention to provide a method for joining dissimilar metal materials that can prevent occurrence of cracks.

"Means for solving the problem" The present invention has been made to solve the above problems,
A joining method of fitting an outer periphery of an inner member that is a part of a plurality of dissimilar metal materials to an opening of an outer member that is a part of a plurality of dissimilar metal materials and joining the outer member. Ts (℃) and Tr respectively
(° C.) and the coefficient of thermal expansion of the outer member is α (K ⁻¹ ), the inner diameter N (mm) of the outer member and the outer diameter G (mm) of the inner member are given by the following two equations. 0.05 ≦ N (1 + α (Ts−Tr)) − G 0.05 ≦ GN ≦ 1.0 The outer member and the inner member were shrink-fitted, and compressive stress was applied to these fitting portions. After fixing in the state, the fitting portion is brazed or melt-welded.

 Hereinafter, this method will be specifically described.

When performing shrink fitting, first, it is important to set the dimensions of each member. For example, when shrink-fitting the outer periphery of an inner member (outer diameter Gmm) into an opening (inner diameter Nmm) of an outer member having an arbitrary shape, these dimensions N and G are set so as to satisfy both of the following two equations. It is desirable (unit: mm).

0.05 ≦ N (1 + α (Ts−Tr)) − G 0.05 ≦ GN ≦ 1.0 where α = coefficient of thermal expansion (K ⁻¹ ) of the outer member, Ts = shrink-fit temperature (° C.), Tr = room temperature (° C.) ).

If the value of the above expression is less than 0.05 mm, shrink fitting becomes difficult. On the other hand, if the expression is less than 0.05 mm, the compressive stress after shrink fitting is small, and the conventional problem cannot be solved. On the other hand, if it is larger than 1.0 mm, shrink fitting becomes difficult, and the compressive stress after shrink fitting becomes too large.

In addition, when joining an annular member to a multiple structure of three or more layers, shrink fitting and cooling may be repeated in order from the inner member.

After shrink fitting is completed, the fitting portion between the outer member and the inner member is joined. Examples of the joining method include brazing and fusion welding. When there is a possibility that the respective materials of the outer member and the inner member are diffused to change the material, brazing is used.
On the other hand, when there is no possibility of a material change due to mutual diffusion, in addition to brazing, fusion welding can be performed using arc welding, electron beam welding, or the like.

When performing brazing, when the outer member or the inner member is made of a material that significantly reacts with the brazing material, or
If the material is extremely poor in wettability with respect to the brazing material, it is preferable to apply a surface treatment such as Ni plating to the joining surface of the member before shrink fitting. In this case, it is possible to prevent the reaction between the brazing material and the member, or to obtain good bonding strength by improving the wettability.

"Operation" In this method, after the interface of each member is fixed in a state where compressive stress is applied by shrink fitting, the boundary portion of each member is brazed or welded. No tensile stress is applied to the joint, and it is possible to prevent the joint from cracking due to this stress.

Further, when the boundary portion between the members is brazed, the region of the material change due to the mutual diffusion between the dissimilar metal materials can be suppressed only to the vicinity of the boundary surface between the brazing material and the member, so that the bonding portion due to the diffusion is formed. No problems such as embrittlement occur.

"Example" Hereinafter, the method for joining dissimilar metal materials according to the present invention will be described in detail with reference to an example in which the method is applied to the manufacture of a composite backing plate.

This composite backing plate is made of a metal disk 1 (outer diameter
G1), first ring 2 (inner diameter N2, outer diameter G2), second ring 3 (inner diameter N3, outer diameter G3), third ring 4 (inner diameter N4, outer diameter G4)
Are concentrically joined together, and the members to be joined are different in material.

The thickness of each of the members was 15 mm, the dimensions were set as follows, and the first ring 2, the second ring 3, and the third ring 4 were shrink-fitted on the outer periphery of the metal disk 1 in this order.

_{N2 (1 + α 2 (Ts} -Tr)) - G1 = 0.2 (mm) N3 (1 + α 3 (Ts-Tr)) - (G2 + G1-N2) = 0.2 (m
_{m) N4 (1 + α 4} (Ts-Tr)) - (G3 + G2-N3) = 0.2 (m
m) Note that α ₂ , α ₃ , and α ₄ are the coefficients of thermal expansion (K ⁻¹ ) of the first to third rings, Ts is the shrink fitting temperature (° C.), and Tr is room temperature (° C.).

Then, after shrink fitting, Ni plating was applied as necessary, and brazing or fusion welding was performed as shown in the separate table, and ten composite backing plates shown in Examples 1 to 14 in the following table were manufactured.

On the other hand, as a comparative example, five types of ten composite backing plates of the same material and the same shape were manufactured by the conventional joining method without shrink fitting. In addition, each dimension was set as follows (unit is mm).

N2 = G1-0.1 N3 = G2-0.2 N4 = G3-0.6 Next, the manufactured backing plates of Examples 1 to 14 and Comparative Examples 1 to 5 were set in a pressurized experiment apparatus shown in FIG. A fatigue crack test was performed. The backing plate 9 is air-tightly fixed to the casing 10, and after applying a water pressure of 10 kg / cm ² for 3 hours by the pressurizing device 12 through the pipe 11,
The release of the water pressure immediately and the application of the water pressure for 3 hours were repeated 5 times continuously. Thus, the number of plates having leaked water from the joint was confirmed.

Next, the plate 9 in which no water leakage occurred was set in the vacuum leak test apparatus shown in FIG. 7, and while the helium gas was blown on the surface side and the inside of the casing 10 was evacuated to a vacuum, the helium leak detector 13 was used. The helium gas leak was examined.

The results of each test are shown in the following table. As is clear from this table, the plates of the examples exhibited good bonding strength and no leakage was observed.

The present invention is not limited to the manufacture of this type of backing plate, but can be applied to a case where dissimilar metal materials are fitted and joined.

[Effects of the Invention] As described above, according to the method for joining dissimilar metal materials according to the present invention, the fitting portion of each dissimilar metal material is fixed in a state where compressive stress is applied by shrink fitting, and then this fitting is performed. Since the joint is welded, no tensile stress is applied to the joint even if each member cools after welding, and cracking of the joint caused by this stress can be prevented.

In addition, when the boundary portion between the dissimilar metal materials after the shrink fitting is brazed, the region of the material change due to the mutual diffusion between the dissimilar metal materials is limited to only the vicinity of the boundary surface between the brazing material and the metal material. Therefore, there is an advantage that problems such as embrittlement of a joint due to diffusion do not occur.

[Brief description of the drawings]

1 to 4 are plan views for explaining an embodiment of the present invention, FIG. 5 is a longitudinal sectional view of a backing plate obtained by the embodiment, and FIGS. 6 and 7 are embodiments. FIG. 8 and FIG. 9 are explanatory diagrams showing the problems of the prior art. 1 ... disk, 2 ... first ring, 3 ... second ring, 4 ... third ring (above, dissimilar metal materials), 9 ... backing plate, P ... joining part.

Claims (1)

(57) [Claims] 1. A joining method in which an outer periphery of an inner member which is a part of a plurality of dissimilar metal materials is fitted and joined to an opening of an outer member which is a part of a plurality of dissimilar metal materials. Ts (° C) and Tr
(° C.) and the coefficient of thermal expansion of the outer member is α (K ⁻¹ ), the inner diameter N (mm) of the outer member and the outer diameter G (mm) of the inner member are given by the following two equations. 0.05 ≦ N (1 + α (Ts−Tr)) − G 0.05 ≦ GN ≦ 1.0 The outer member and the inner member were shrink-fitted, and compressive stress was applied to these fitting portions. A method for joining dissimilar metal materials, comprising fixing the fitting portion to a state and then brazing or fusion-welding the fitting portion.