JPS62202732A - Composite material consisting of graphite and copper or copper alloy - 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 [Field of Industrial Application] The present invention relates to a composite material made of graphite and copper or a copper alloy, which is used, for example, in X-ray targets, sputtering targets, and the like.

[Conventional technology]

Copper and copper alloys and graphite have significantly different coefficients of thermal expansion. The linear expansion coefficient of steel and copper alloy is 18~20X
IO″6, whereas the linear expansion coefficient of graphite is 3 to 1 ×
10"6. Generally, the range in which the coefficient of thermal expansion does not pose a practical problem in brazing or diffusion bonding is when the difference in linear expansion and coefficient between the two is smaller than 10XIO".

For this reason, when the two are joined by hard brazing or diffusion bonding, the shrinkage rate of the copper plate is greater during the cooling process after joining, resulting in a dimensional difference between the two and a large residual stress. The board may be destroyed.

For example, as shown in FIG. 9, suppose that a graphite plate 1 and a copper plate 2 are stacked on each other in the thickness direction and are diffusion bonded (or hard brazed) at high temperature. In this case, the copper plate 2 contracts relative to the graphite plate 1 during the cooling process after bonding. Therefore, if there is a large temperature difference between the bonding temperature and the cooling temperature, the graphite plate 1 and the copper plate 2 will bend as shown by the imaginary lines in Figure 9, and in extreme cases, as shown in Figure 10. Radial cracks 3 appear on the graphite plate 1. For this reason, the composite material consisting of the graphite plate 1 and the copper plate 2 may be able to be joined with a small test piece, but the graphite plate 1 often breaks when it is of a practical size.

Therefore, at present, they are joined by mechanical means, by resin-based adhesive, or by soft brazing using indium, solder, or the like at a relatively low temperature.

[Problem that the invention seeks to solve]

However, in mechanical fastening, the load is applied locally, so the fastening force cannot be increased very much. on the other hand,
Bonding using a resin adhesive or soft brazing has poor heat resistance at the bonded portion, which poses a problem for those used at high temperatures, such as X-ray targets and sputtering targets.

Moreover, when used in a vacuum or special atmosphere, there is a possibility that impurity gases will be generated from the adhesive.

[Means for solving problems]

The composite material of the present invention comprises a graphite plate, a copper plate made of pure copper or a copper alloy, and an insert plate made of a metal whose coefficient of thermal expansion is smaller than that of the copper plate, and the graphite plate and the copper plate are bonded by diffusion bonding or hardening. They are bonded to each other via the insert plate by a high-temperature bonding means such as brazing. The insert plate is preferably made of a metal having a higher elastic modulus than the copper plate.

[Effect]

In the composite material having the above structure, the copper plate and the graphite plate are joined with a heat-resistant insert plate interposed therebetween, so that shrinkage of the copper plate is suppressed by the insert plate during the cooling process after joining. Therefore, the deflection of the composite material is reduced, and it is possible to prevent the graphite plate from cracking or breaking during the cooling process.

Since the graphite plate and the copper plate of the above-mentioned composite material are bonded to each other in a plane by a bonding method performed at high temperature such as hard brazing, brazing or diffusion bonding, the bonding strength between the two is high and heat resistant. Furthermore, compared to bonding using adhesives, the heat resistance is far superior, and there is no risk of gas release in a vacuum atmosphere.

〔Example〕

In one embodiment shown in FIG. 1, the composite material 5 includes a graphite plate 6, a copper plate 7 made of pure copper or a copper alloy, and an insert plate 8 provided between the graphite plate 6 and the copper plate 7. It is equipped with

The insert plate 8 is made of a metal having a coefficient of thermal expansion smaller than that of the copper plate 7 and a melting point equal to or higher than that of the copper plate 7 . Target metals are Hf, Ir, Mo, N
b, Os, Pt, Ta.

These are Ti, V, Zr, W, and alloys of these metals. The coefficient of linear expansion of the insert plate 8 may be close to the coefficient of linear expansion of the graphite plate 6 or a value intermediate between that of the graphite plate 6 and the copper plate 7. Specifically, when the linear expansion coefficient of graphite is αC, (aa-3x10″!1≦αC≦αC+5×10″6)
If a metal within the range of 2 is used, bonding with the graphite plate 6 is possible.

The thickness of the copper plate 7 is practically about 2~'aOrnm, whereas the thickness of the insert plate 8 depends on its elastic modulus, but it is practically about 1/200 nm of the thickness of the copper plate 7. 20
to 115 degrees, that is, around 0.1 to 2°Orm, is used. Since it is desirable that the insert plate 8 has high rigidity, it is preferable to select a material whose elastic modulus is higher than that of the copper plate 7.

Considering the above, the material of the insert plate 8 is M
Metals with low melting properties and low thermal expansion, such as O, W, and Nb, or alloys thereof are suitable.

The insert plate 8 is sandwiched between the graphite plate 6 and the copper plate 7,
By heating to the bonding temperature and applying pressure in the thickness direction, the graphite plate 6 and the copper plate 7 are diffusion bonded via the insert plate 8. In addition, the graphite plate 6 and the insert plate 8
By interposing an appropriate hard brazing material between the copper plate 7 and the insert plate 8, the joining may be performed by hard brazing. The bonding temperature is, for example, about 800 to 1000°C.

During the cooling process after bonding, the shrinkage rate of the copper plate 7 is greater than that of the graphite plate 6, but a highly rigid insert plate 8 is sandwiched between the graphite plate 6 and the copper plate 7, and they are diffusion bonded to each other. Since they are firmly joined by hard brazing, shrinkage of the copper plate 7 due to the difference in coefficient of thermal expansion can be suppressed. As a result, the deflection of the composite material 5 is reduced, and the occurrence of cracks in the graphite plate 6 is prevented.

The melting point of the insert plate 8 is equal to or higher than the melting point of the copper plate 7, and since the graphite plate 6 and the copper plate 7 are bonded to each other by a bonding method performed at high temperature, the composite material 5 has excellent heat resistance. Demonstrate your sexuality. Moreover, the thickness of the insert plate 8 is 1/20 to 1/20 of the thickness of the copper plate 7.
Since it is as thin as 2, it has little effect on the thermal conductivity between the graphite plate 6 and the insert plate 8. Moreover, not only does it not impose localized loads as in the case of mechanical fastening, but also does not cause the release of contaminants as in the case of using adhesives. Furthermore, since graphite has excellent heat resistance of about 2500° C. in a non-oxidizing atmosphere, by cooling the copper plate 7 side by an appropriate means, it exhibits excellent high temperature heat resistance.

For these reasons, the composite material 5 is suitable for X-ray targets, sputtering targets, and the like.

FIG. 2 shows an example of the X-ray target 10. This target 10 includes:
A composite material 5 shown in FIG. 3 is used. This composite material 5
In this method, an end surface 6a of a graphite plate 6 is processed into a tapered shape, and characteristic X-rays of carbon are generated by applying an electron beam to this tapered end surface 6a. In order to cope with the temperature rise at that time, a cooling cylinder 11 is provided on the copper plate 7 side, and a coolant such as cooling water is passed through the cooling cylinder 11 through pipes 12.13 to cool the graphite plate 6 through the copper plate 7. Do this.

Such an X-ray target must have heat resistance of several hundred degrees Celsius and must not emit impurity gas even in a vacuum atmosphere. Furthermore, the target 10 is rotated around its axis at high speed in order to prevent local heating, so it must have high bonding strength. is required. The composite material 5 of this example is suitable as one that satisfies these requirements. In addition, in the composite material 5 of the embodiment shown in FIG. 4, a tapered recess 7a is provided in the copper plate 7.

The sputtering apparatus shown in FIG. 5 coats a material to be bonded (not shown) with graphite, and uses the composite material 5 of the present invention as a target.

The structure of this composite material 5 is basically the same as that of the composite material 5 described above (FIG. 1), in which a graphite plate 6 and a copper plate 7 are bonded together at high temperature via an insert plate 8. Typically, during sputtering, the surface of the target is heated to a high temperature so that the opposite side of the target is cooled. In the illustrated example, the target, that is, the composite material 5 is cooled by supplying the refrigerant 15 to the copper plate 7 side through the refrigerant supply pipe J4. In this case, the copper plate 7 also serves as a presser back metal. In the figure, 16 is a magnet.

In order to increase the sputtering speed, it is necessary to increase the energy input to the target, but the conventional bonding methods using resin adhesives and soft brazing have a heat resistance of 200°C or less. There is a problem in terms of heat resistance. On the other hand, the target using the composite material 5 according to the present invention has significantly superior heat resistance, so that a larger amount of energy can be input, and the sputtering speed can be improved.

The joining shape of the composite material 5 or the graphite plate 6 used for the target may be an annular shape as shown in FIG. 6, a rectangular shape as shown in FIG. 7, or a U-shape as shown in FIG.
Various shapes are possible.

〔Effect of the invention〕

According to the present invention, when a graphite plate and a copper plate having significantly different coefficients of thermal expansion are bonded to each other by high-temperature bonding means such as diffusion bonding or hard brazing, damage to the graphite can be prevented. Moreover, the composite material of the present invention has excellent heat resistance and bonding strength, and there is no fear of releasing impurity gas into the atmosphere.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a composite material showing one embodiment of the present invention;
3 is a cross-sectional view of the composite material shown in FIG. 2, and FIG. 4 is a perspective view of an X-ray target using a composite material showing another embodiment of the present invention. FIG. 5 is a cross-sectional view of a sputtering device, and FIGS. 6 to 8 are plan views showing examples of different shapes of the composite material. FIG. 9 is a side view showing an example of a conventional composite material, and FIG. 10 is a plan view of the composite material shown in FIG. 9 in which a crack has occurred. 5... Composite material, 6... Graphite plate, 7... Copper plate, 8...
...insert board. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 a Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10

Claims (2)

[Claims] (1) A graphite plate, a copper plate made of pure copper or a copper alloy, and an insert plate made of a metal with a coefficient of thermal expansion smaller than that of the copper plate, and the graphite plate and the copper plate are bonded by diffusion bonding, hard brazing, etc. A composite material made of graphite and copper or a copper alloy, characterized in that they are bonded to each other via the insert plate by a bonding method performed at high temperature. (2) The composite material made of graphite and copper or a copper alloy according to claim 1, wherein the insert plate is made of a metal whose elastic modulus is higher than that of the copper plate.