JP4500065B2 - Joining method of alumina member and copper electrode, and joined body of alumina member and copper electrode - Google Patents

Description

The present invention relates to conjugates of the bonding method, and high-purity alumina member and the copper electrode of the high purity alumina member and the copper electrode.

The so-called DBC method (Direct Bonding
Copper) method is known as a method for bonding copper to ceramics, and is described in, for example, Patent Document 1 and Patent Document 2. In this method, for example, tough pitch copper is directly placed on an alumina substrate, and in a state where the tough pitch copper and the alumina substrate are brought into contact in an inert atmosphere, 1065 ° C. (copper eutectic temperature) to 1083 ° C. (dissolution of copper) Temperature). As a result, a eutectic liquid phase of a copper oxide phase and a copper aluminate phase is generated at the bonding interface between alumina and copper. After wetting the surface of the alumina member with the eutectic liquid phase, the alumina member and the copper member are joined by cooling and solidifying the copper oxide phase and the copper aluminate phase.

JP 59-3076

JP 59-3077

  However, this method has the following limitations. First, it is necessary to heat-treat to tough pitch copper at or above the eutectic temperature of copper. For this reason, if the alumina substrate or tough pitch copper is not flat, it is difficult to make contact over the entire surface, so only a flat plate is actually applied. For this reason, for example, when a plate-like or round bar-like copper member is joined to a cylindrical ceramic (alumina) member, it is difficult to improve the contact between the two in terms of shape and the joining area can be increased. In some cases, it was difficult to obtain sufficient bonding strength.

  In addition to this, when the purity of the alumina member is, for example, about 96% by weight, a eutectic liquid phase is likely to be generated between the alumina member and the copper member, whereby a high bonding force is easily obtained. However, according to the present inventors, in the case of a high-purity alumina member having a purity of 99.5% by weight or more, the above method can join the high-purity alumina member and the copper member with a high bonding force. It turned out that it might be difficult. This was thought to be due to the fact that the alumina member has a high purity, so that the formation of the eutectic liquid phase at the bonding interface is suppressed.

  For this reason, this inventor also examined joining a high purity alumina member and a copper member with a silver type active brazing material. However, such a brazing material is vulnerable to corrosive substances such as a fluorine-based corrosive gas, and easily causes contamination of the atmosphere. In particular, when a copper member is used as a copper electrode, such contamination of the atmosphere becomes a problem.

  An object of the present invention is to provide a new method for joining a high-purity alumina member and a copper member.

  Another object of the present invention is to obtain a bonded body that is resistant to corrosion by a corrosive substance such as a fluorine-based corrosive gas by bonding a high-purity alumina member and a copper member.

The present invention
A joining method of an alumina member having a purity of 99.5% by weight or more and a copper electrode having an oxygen content of 100 ppm or less and a copper purity of 99.9% by weight or more,
A paste-like brazing material having the following composition is interposed between the alumina member and the copper electrode, and heat treatment is performed at 1000 ° C. or more and 1083 ° C. or less in an inert atmosphere or under vacuum, characterized by having a bonding step of bonding the copper electrode, it relates to a method of joining the alumina member and the copper electrode.
CuO: 95.0 to 99.5% by weight
Ti: 0.5 to 5.0% by weight

Further, the present invention is a joined body of a tubular alumina member having a purity of 99.5% by weight or more and a copper electrode having an oxygen content of 100 ppm or less and a copper purity of 99.9% by weight or more,

The copper electrode is joined to the inner peripheral surface or the outer peripheral surface of the alumina member, and the alumina member and the copper electrode are joined by a brazing material having the following composition.
CuO: 95.0 to 99.5% by weight
Ti: 0.5 to 5.0% by weight

The present inventor has found that a high purity alumina member and a copper electrode can be joined by interposing a brazing material having the above composition and heat-treating in an inert atmosphere or under vacuum. This brazing material is mainly composed of copper oxide and / or copper. This provided a practical method for joining high purity alumina and copper. Further, according to the method of the present invention, the high-purity alumina member having a curved surface and the copper electrode can be reliably bonded. As a result, there are no restrictions due to the shape of the high-purity alumina member or the copper electrode , and for example, a tubular high-purity alumina member can be joined.

  Furthermore, the joined body obtained by this method has a small amount of material having inferior corrosion resistance at the joint interface, and is resistant to corrosion by corrosive substances such as fluorine-based corrosive gases.

Hereinafter, the present invention will be described in detail with reference to the drawings.
For example, as shown in FIG. 1A, a brazing material 6 is interposed between the joining surface 1a of the high purity alumina member 1 and the copper member 4 and laminated. Next, as shown in FIG. 1B, the high-purity alumina member 1 and the copper member 4 were successfully joined by heat treatment in an inert gas atmosphere or under vacuum. 6A is a bonding layer, and 8A is a bonded body.

The composition of this brazing material is as follows.
CuO: 95.0 to 99.5 % by weight
Ti: 0.5 to 5.0% by weight

In the brazing material, if the CuO content is less than 95.0% by weight, the corrosion resistance of the joined body is lowered. From this viewpoint, the CuO content is set to 95.0% by weight or more.

Brazing material does not contain substantially Cu, the content of CuO in the brazing material is 95.0 to 99.5 wt%.

The content of the titanium component definitive the brazing material is 0.5 wt% or more. However, if the content of the titanium component exceeds 5.0% by weight, the corrosion resistance of the joined portion of the joined body is lowered, so the content of the titanium component is 5.0% by weight or less.

  The brazing material may contain components other than copper oxide, copper, and titanium. However, the proportion of such components is preferably 5.0% by weight or less, more preferably 0.5% by weight or less, and particularly preferably not substantially contained from the viewpoint of corrosion resistance. Examples of such other components include Al and Ni.

The brazing material is a paste. By making it into a paste form, the brazing material can be reliably disposed on the curved surface by a method such as coating, and the shape followability is excellent. In addition to copper oxide and titanium, additives such as various dispersants, binders, and viscosity modifiers known as brazing materials can be added to the paste.
The following can be illustrated as such a paste preparation method.
To make a paste, add a vehicle containing acrylic binder as the main ingredient (solution mixed with dispersant, binder, diluent, etc. when making the paste) to the raw material powder, and knead with a mortar, three rolls, etc. Use paste.

Temperature during the heat treatment, from the viewpoint of improving the bonding strength state, and are 1000 ° C. or higher, further preferably 1030 ° C. or more, and most preferably 1050 ° C. or higher. The heating temperature is preferably, therefore 1083 ° C. or less is not more than the melting point of copper.

In this invention, the oxygen content of a copper member is 100 ppm or less, and the purity of copper is 99.9 weight% or more, for example, it is what is called an oxygen-free copper.

  In the joined body of the present invention, since the copper electrode is joined to the high-purity alumina member, power supply from the electrode is stable. Furthermore, it has high durability against corrosive substances, and even when used for a long time in an environment exposed to corrosive substances, dielectric breakdown is unlikely to occur.

In a preferred embodiment, the joined body of the present invention should be exposed to corrosive substances. Examples of such corrosive substances include acids and alkalis in addition to halogen-based corrosive gases such as chlorine-based corrosive gases and fluorine-based corrosive gases. In addition, examples of the fluorine-based corrosive gas include KrF, ArF, and F ₂ gases and plasmas thereof.

  In the joining method of the present invention, in order to improve the contact between the high-purity alumina member and the copper member in the joining step, it is possible to apply pressure, but pressurization is not always necessary. As a result, even if the high-purity alumina member or the copper member has a shape in which pressurization is difficult or impossible, it is possible to firmly bond both of them. Also in this respect, the present invention is extremely useful industrially.

  Therefore, the shape of the high purity alumina member or the copper member is not particularly limited, and may be a corrugated plate shape or a curved plate shape in addition to a flat plate shape. Moreover, the shape which has a tubular shape (tube shape) and another curved surface may be sufficient.

  In a particularly preferred embodiment, one of the high-purity alumina member and the copper member is tubular, and the other is joined to the outer peripheral surface and / or the inner peripheral surface of the tubular member. 2, 3 and 4 relate to this embodiment.

  In the joined body 8B shown in FIGS. 2A and 2B, an elongated copper member 4A having an arc cross section is joined to the inner peripheral surface 1b of the tubular high-purity alumina member 1A. Reference numeral 7 denotes an internal space of the high-purity alumina member 1A, and reference numeral 1a denotes an outer peripheral surface. The method for joining the high purity alumina member 1A and the copper member 4A has been described above.

  In the joined body 8C shown in FIGS. 3A and 3B, the outer peripheral surface 4a of the elongated cylindrical copper member 4B is joined to the inner peripheral surface 1b of the tubular high-purity alumina member 1A. The method for joining the high purity alumina member 1A and the copper member 4B has been described above.

  In the joined body 8D shown in FIGS. 4A and 4B, the inner peripheral surface 4a of the copper member 4C having an elongated arc shape is joined to the outer peripheral surface 1a of the tubular high-purity alumina member 1A.

  The joined body of the present invention can be applied to a joined body of a copper electrode and a high-purity alumina member. Such a bonded body is excellent in the following points. That is, the high-purity alumina member joined with the copper electrode has high insulation durability, and dielectric breakdown does not easily occur even when used for a long time. Moreover, since the copper electrode and the alumina member are joined, the power supply from the electrode is stable. Furthermore, such a joined body has high durability against corrosive substances, and even when used for a long time in an environment exposed to corrosive substances, dielectric breakdown does not easily occur.

  The copper electrode of the present invention can be suitably used as an electrode device for an excimer laser device, particularly as a corona discharge electrode. Hereinafter, this embodiment will be described.

  FIG. 5A is a cross-sectional view schematically showing a conventional electrode 20, and FIG. 5B is a cross-sectional view showing a main part of this electrode device.

  In an excimer laser oscillator, a mixed gas of a rare gas and a halide is supplied between an anode and a cathode, and a pulse voltage is applied. At this time, deep ultraviolet photons are generated from the electrode device. At this time, an electrode device using a cylindrical high-purity alumina member 14 is used. In FIG. 5, the cylindrical high-purity alumina member 14 is fixed at a fixed position by the pressing member 10. And the outer electrode 12 is installed in the outer peripheral surface 14b of the high purity alumina member 14, and the outer electrode 12 is fixed to a predetermined position with the pressing member 11. FIG. At the same time, a cylindrical inner electrode 13 is fixed in the internal space of the high-purity alumina member 14 as shown in FIG. Here, the positioning of the inner electrode 13 is performed by a predetermined number of spacers 15. Thereby, the space | interval of the outer peripheral surface 13a of the inner side electrode 13 and the inner peripheral surface 14a of the high purity alumina member 14 is kept constant. The outer electrode 12 and the inner electrode 13 are copper electrodes.

  As described above, the high-purity alumina member 14, the outer electrode 12, and the inner electrode 13 are fixed in place. As a result, the relative positional relationship between the members should be fixed, and the discharge state from the electrodes should be stable.

  However, in practice, it is necessary to fix the outer electrode 12 and the inner electrode 13 in place by jigs. Further, the interface between the inner electrode and the high purity alumina member is not in close contact, and the adhesion between the outer electrode and the high purity alumina member is also low. For this reason, it is difficult to cause uniform corona discharge, and uneven discharge tends to occur. For this reason, partial wear is likely to occur in the high-purity alumina member, and the lifetime is short.

  FIG. 6A is a sectional view schematically showing an electrode device 21 having the joined body 8E of the present invention, and FIG. 6B is a cross-sectional view of the main part of the joined body 8E.

  In FIG. 6, the cylindrical high-purity alumina member 14 is fixed in place by the holding member 10. Then, the outer electrode 12 is joined to the outer peripheral surface 14 b of the high purity alumina member 14. At the same time, a cylindrical inner electrode 13 is joined to the internal space of the high-purity alumina member 14 as shown in FIG. The outer electrode 12 and the inner electrode 13 are copper electrodes.

  According to such an electrode device, it is not necessary to fix the outer electrode 12 and the inner electrode 13 with a jig. Moreover, the adhesiveness in the interface of an inner side electrode and a high purity alumina member and the interface of an outer side electrode and a high purity alumina member is high. Further, the positional relationship among the outer peripheral surface 13a of the inner electrode 13, the inner peripheral surface 14a of the high-purity alumina member 14, and the outer electrode 12 is kept constant. For this reason, uniform corona discharge can be performed, and non-uniform discharge hardly occurs. For this reason, partial wear is unlikely to occur in the high-purity alumina member, and the life is extended.

  The kind of high purity alumina is not limited. However, translucent alumina is particularly preferred. Translucent alumina is alumina having a total light transmittance of 80% or more in the visible light (600 (nm)) region. The light-transmitting alumina is particularly preferably a high-purity alumina having a purity of 99.9%, which is used as a raw material by adding an additive for controlling the particle size during sintering. A molded body is produced by an isostatic press, an extrusion technique, etc., the molded body is degreased, and the degreased body is fired at 1700 to 1900 ° C. in a hydrogen atmosphere. The fired body is composed of uniform hexagonal grains.

Example 1
A joined body 8B shown in FIGS. 2 (a) and 2 (b) was manufactured according to the above-described procedure. A translucent alumina ceramic tube 1A (outer diameter 14 mm, inner diameter 10 mm, total length 800 mm) having a purity of 99.9% was prepared. In addition, a copper member 4A made of oxygen-free copper was prepared. The oxygen content of the copper member 4A is 10 ppm or less, and the purity of copper is 99.96% by weight. The outer diameter of the copper member 4A is 9.8 mm, the thickness is 0.3 mm, and the length is 800 mm. The copper member 4A was inserted into the tube 1A.

  A paste of brazing material was applied to the outer peripheral surface 4a of the copper member 4A to form a coating film, and the coating film was brought into contact with the inner peripheral surface 1a of the tube 1A. The composition of the brazing filler metal was 99.5 wt% CuO and 0.5 wt% Ti. Next, the tube was accommodated in a vacuum furnace, and bonded under conditions of a maximum temperature of 1075 ° C. and a holding time of 5 to 10 minutes at a maximum temperature under a pressure of 10 Torr or less to obtain a bonded body 8B. The obtained bonded body 8B had no crack at the bonding interface due to a difference in thermal expansion, had good adhesion, and had a good bonding state.

(Example 2)
A joined body 8C shown in FIGS. 3A and 3B was manufactured according to the same procedure as in Example 1. The high purity alumina member 1A is the same as that of the first embodiment. Moreover, the cylindrical copper member 4B which consists of oxygen-free copper was prepared. The oxygen content of the copper member 4B is 10 ppm or less, and the purity of copper is 99.96% by weight. The outer diameter of the copper member 4B is 9.5 mm and the length is 820 mm. A paste of brazing material was applied to the outer peripheral surface 4a of the copper member 4A to form a coating film, and the coating film was brought into contact with the inner peripheral surface 1a of the tube 1A. The composition of the brazing filler metal was 99.5% by weight of CuO and 0.5% by weight of Ti. Next, the tube 1A was accommodated in a vacuum furnace, and joined under conditions of a maximum temperature of 1075 ° C. and a maximum temperature holding time of 5 to 10 minutes under a pressure of 10 Torr or less to obtain a joined body 8B. The obtained joined body was free from cracks at the joining interface due to a difference in thermal expansion, had good adhesion, and had a good joined state.

(Example 3)
Following the same procedure as in Example 1, a joined body 8D shown in FIGS. However, the high-purity alumina member 1A is the same as that of the first embodiment. In addition, a copper member 4C having an arcuate cross section made of oxygen-free copper was prepared. The oxygen content of this copper member 4C is 10 ppm or less, and the purity of copper is 99.96% by weight. The inner diameter of the copper member 4C is 14 mm, the thickness is 0.5 mm, and the length is 800 mm.

  A brazing material paste was applied to the outer peripheral surface 1a of the tube 1A to form a coating film. The composition of the brazing filler metal was 99.5% by weight of CuO and 0.5% by weight of Ti. The inner peripheral surface 4a of the copper member 4C was brought into contact with the coating film. Next, the tube 1A was accommodated in a vacuum furnace, and joined under conditions of a maximum temperature of 1075 ° C. and a holding time of 5 to 10 minutes at a maximum temperature under a pressure of 10 Torr or less to obtain a joined body 8D. The obtained joined body was free from cracks at the joining interface due to a difference in thermal expansion, had good adhesion, and had a good joined state.

  Each joined body of Examples 1 to 3 was used to manufacture an excimer laser oscillator electrode (see FIG. 6). As a result, there was little wear over a long period of time in a corrosive gas environment, and a good discharge state could be maintained.

(Comparative Example 1)
In Example 1, the brazing material was not used. Others tried joining on the same conditions as Example 1, but did not join.

(Comparative Example 2)
In Example 2, the brazing material was not used. Others tried joining on the same conditions as Example 2, but did not join.

(Comparative Example 3)
In Example 3, the brazing material was not used. Others tried joining on the same conditions as Example 3, but did not join.

  As described above, according to the present invention, a new method for joining a high-purity alumina member and a copper member can be provided. Further, the high-purity alumina member and the copper member can be joined without the need to apply a high pressure, thereby reducing restrictions due to the shapes of the high-purity alumina member and the copper member. Furthermore, by joining the high-purity alumina member and the copper member, it is possible to obtain a joined body that is resistant to corrosion by corrosive substances such as fluorine-based corrosive gas.

(A) is a front view which shows the high purity alumina member 1, the brazing material 6, and the copper member 4, (b) is a front view which shows 8 A of joined bodies. (A) is a cross-sectional view showing a joined body 8B of a tubular high-purity alumina member 1A and a copper member 4A having an arcuate cross section, and (b) is a sectional view taken along the line IIb-IIb of the joined body 8B. . (A) is a cross-sectional view showing a joined body 8C of a tubular high-purity alumina member 1A and a cylindrical copper member 4B, and (b) is a sectional view taken along the line IIIb-IIIb of the joined body 8C. (A) is a cross-sectional view showing a joined body 8D of a tubular high-purity alumina member 1A and a cylindrical copper member 4C, and (b) is a longitudinal sectional view of the joined body 8D. (A) is sectional drawing which shows the conventional electrode apparatus 20 roughly, (b) is principal part sectional drawing of the electrode apparatus of (a). (A) is sectional drawing which shows schematically the electrode apparatus 21 using the conjugate | zygote based on this invention, (b) is principal part sectional drawing of the electrode apparatus 21 of (a).

Explanation of symbols

1, 1A, 14 High-purity alumina member 1a, 1b, 14a, 14b Bonding surface of high-purity alumina member 4, 4A, 4B, 4C, 12, 13 Copper member 4a, 13a Bonding surface of copper member 6 Brazing material 6A
Bonding layer
8, 8A, 8B, 8C, 8D, 8E Assembly 21 Electrode device

Claims (10)

A joining method of an alumina member having a purity of 99.5% by weight or more and a copper electrode having an oxygen content of 100 ppm or less and a copper purity of 99.9% by weight or more,
A paste-like brazing material having the following composition is interposed between the alumina member and the copper electrode, and heat treatment is performed at 1000 ° C. or more and 1083 ° C. or less in an inert atmosphere or under vacuum. It characterized by having a bonding step of bonding the a member of copper electrode, method of joining the alumina member and the copper electrode.
CuO: 95.0 to 99.5% by weight
Ti: 0.5 to 5.0% by weight The method according to claim 1, wherein the alumina member is tubular, and the copper electrode is joined to an inner peripheral surface or an outer peripheral surface of the alumina member. The method according to claim 2 , wherein the copper electrode is a corona discharge electrode. The method according to claim 2 , wherein the copper electrode has a cylindrical shape and is joined to the inner peripheral surface of the alumina member. It characterized in that the alumina member is a translucent alumina member, the method according to any one of claims 1-4. A joined body of a tubular alumina member having a purity of 99.5% by weight or more and a copper electrode having an oxygen content of 100 ppm or less and a copper purity of 99.9% by weight or more,

The said copper electrode is joined to the internal peripheral surface or the outer peripheral surface of the said alumina member , The said alumina member and the said copper electrode are joined by the brazing material which has the following composition, The joined body characterized by the above-mentioned. .
CuO: 95.0 to 99.5% by weight
Ti: 0.5 to 5.0% by weight The joined body according to claim 6 , wherein the joined body is used in an environment exposed to a fluorine-based corrosive gas. The joined body according to claim 6 , wherein the copper electrode is a corona discharge electrode. The joined body according to claim 6, wherein the copper member has a columnar shape and is joined to the inner peripheral surface of the alumina member. The joined body according to any one of claims 6 to 9 , wherein the alumina member is a translucent alumina member.

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