JP6092557B2 - Manufacturing method of discharge lamp electrode - Google Patents

Description

  The present invention relates to a discharge lamp used for an exposure apparatus or the like, and more particularly to a method for manufacturing a discharge lamp electrode in which a plurality of members are joined.

  In the discharge lamp, as the output increases, electrodes having different metal types and crystal characteristics are joined to form an electrode. For example, a metal member containing an emitter such as thorium is used as an electrode tip portion, and a refractory metal member such as pure tungsten is used as a body portion, and the two metal members are joined to each other. Thereby, the thorium content of the whole electrode is reduced.

  As a bonding method, diffusion bonding which is one of solid phase bonding is used (see Patent Document 1). In this case, a columnar tritium tungsten (tritan) member constituting the electrode tip and a columnar tungsten member constituting the body part are prepared. Then, contact surfaces having the same diameter are brought into contact with each other and energized and heated while applying pressure from both sides of the member. After diffusion bonding, the tip end side of the integrated member is cut into a conical shape to obtain an electrode shape.

JP 2012-15007 A

  The section of the triated tungsten member has a lower smoothness than the section of the tungsten member. This difference in smoothness becomes more conspicuous as the diameter increases. For this reason, the bonding strength becomes nonuniform on the bonding surface, and a stable bonding strength cannot be obtained.

  In addition, when diffusion bonding is performed by energization heating, current tends to flow to the surface side due to the skin effect, and the bonding strength near the periphery of the bonding surface is larger than the center portion. For this reason, when the tip portion is formed by cutting after diffusion bonding, a portion near the surface having a high bonding strength is scraped more, and the bonding strength is reduced.

  Therefore, it is necessary to solid-phase bond the member constituting the tip portion containing the emitter, such as triated tungsten, and the member constituting the body portion without destabilizing the bonding strength.

  The method for manufacturing an electrode for a discharge lamp of the present invention comprises at least a part of an electrode tip part, a columnar tip solid member containing an emitter, and at least an electrode body part, and more than a joining surface of the tip solid member. Columnar fuselage solid members having a large-diameter joining surface are solid-phase joined via each other's joining surface, and are cut to form a tapered electrode tip with respect to the electrode material generated by solid-phase joining. It is characterized by processing.

  For example, a cathode is manufactured as an electrode and used for a discharge lamp. Triated tungsten or the like can be applied as the emitter, and the shape of the tip solid member or the body solid member is arbitrary, and a metal material or a ceramic material can be applied as the material. As the solid phase bonding method, various diffusion bondings can be applied, and in particular, solid phase bonding can be performed by SPS bonding.

  In the present invention, the diameter of the tip solid member is smaller than the diameter of the body solid member. Then, by performing the cutting process after the solid phase bonding, it is possible to form an electrode in which a wedge portion is easily generated and only the end portion of the bonding surface having a low bonding strength is efficiently removed.

  For example, at the time of a cutting process, it is possible to cut at least the peripheral portion of the joint surface between the tip solid member and the body solid member in the electrode material. In particular, in the electrode material, cutting can be performed so as to remove the wedge portion formed at the peripheral portion of the joint surface of the tip solid member. Moreover, in an electrode raw material, it can also cut so that only the center part of the joint surface of a front-end | tip solid member may remain.

  In order to enable such cutting, the ratio of the diameter of the joining surface of the front solid member and the diameter of the joining surface of the fuselage solid member is configured to satisfy 0.05 <D1 / D2 <1. Also good.

  On the other hand, the method for producing an electrode for a discharge lamp in another aspect of the present invention is a method for producing an electrode further provided with an intermediate member, and constitutes at least a part of an electrode tip and includes a columnar tip solid containing an emitter The member and a columnar intermediate solid member having a joint surface having the same diameter as the joint surface of the tip solid member are solid-phase joined via the joint surfaces, and the intermediate solid member and the joint surface of the intermediate solid member Also, the columnar fuselage solid member that has at least a large-diameter joining surface and that constitutes at least the electrode body part is solid-phase joined via each joining surface, and is tapered to the electrode material generated by solid-phase joining. It cuts so that the electrode front-end | tip part may be formed.

  According to the present invention, an electrode can be constituted from a plurality of members without deteriorating electrode performance.

It is the top view which showed typically the discharge lamp which is 1st Embodiment. It is a schematic sectional drawing of a cathode. It is the figure which showed the manufacturing process of the cathode. It is the figure which showed the process of the cutting process in 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a plan view schematically showing a discharge lamp according to the first embodiment.

  The short arc type discharge lamp 10 is a discharge lamp that can be used as a light source of an exposure apparatus (not shown) for pattern formation, and includes a transparent quartz glass discharge tube (light emitting tube) 12. A cathode 20 and an anode 30 are opposed to the discharge tube 12 with a predetermined interval.

  On both sides of the discharge tube 12, sealing tubes 13A and 13B made of quartz glass are provided integrally with the discharge tube 12 so as to face each other, and caps 19A and 19B are provided at both ends of the sealing tubes 13A and 13B. Has been placed.

  In the discharge lamp 10, the anode 30 and the cathode 20 are arranged on the same axis as the discharge lamp 10. The cathode 20 includes a conical tip portion 20A and a body portion 20B.

  Inside the sealing tubes 13A and 13B, conductive electrode support rods 17A and 17B for supporting the metallic cathode 20 and the anode 30 are disposed, and a metal ring (not shown), a metal foil 16A such as molybdenum, etc. , 16B to the conductive lead rods 15A, 15B, respectively.

  The sealing tubes 13A and 13B are welded to glass tubes (not shown) provided in the sealing tubes 13A and 13B, thereby sealing the discharge space DS in which mercury and a rare gas are sealed. The

  The lead rods 15A and 15B are connected to an external power source (not shown), and are connected between the cathode 20 and the anode 30 via the lead rods 15A and 15B, the metal foils 16A and 16B, and the electrode support rods 17A and 17B. A voltage is applied to. When electric power is supplied to the discharge lamp 10, arc discharge occurs between the electrodes, and a bright line (ultraviolet light) due to mercury is emitted.

  FIG. 2 is a schematic cross-sectional view of the cathode 20.

  The cathode 20 employs an electrode structure in which two metal members 110 and 120 are joined and then formed by cutting. The metal member 110 constitutes a part of the tip portion 20A, and the metal member 120 constitutes a columnar body portion 20B and a body side portion of the tip portion 20A.

  The metal member 110 is a metal member made of triated tungsten, which is tungsten containing tria (ThO2: thorium dioxide), and the metal member 120 is a metal (here, pure tungsten) having a higher thermal conductivity than the metal member 110. ).

  The metal members 110 and 120 are diffusion-bonded according to spark plasma sintering (SPS (Spark Plasma Sintering)). Therefore, a diffusion layer is formed in the vicinity of the joint surface S perpendicular to the electrode axis E. The diameter of the metal crystal is substantially uniform along the bonding surface S. Regarding the electrode axis E, the crystal diameter is substantially uniform except for the vicinity of the joint surface S. By forming such a diffusion layer sandwiching the bonding surface S, there is no variation along the bonding surface S with respect to heat conduction characteristics and conductivity.

  FIG. 3 is a diagram showing a manufacturing process of the cathode 20. The SPS joining and cutting will be described with reference to FIG. The anode can be manufactured in the same manner.

  First, cylindrical metal members 110 and 120 are formed, respectively. At this time, the diameter D1 of the metal member 110 is formed to be smaller than the diameter D2 of the metal member 120. Here, when 3 <D1 <30 and 5 <D2 <60 (both in mm), the diameters D1 and D2 are determined so as to satisfy 0.05 <D1 / D2 <1. The upper limit value is determined so as to delete at least a wedge portion described later. The lower limit value is determined according to the inclination angle of the electrode tip, bonding conditions, and the like.

  An SPS bonding process is performed on the prepared metal members 110 and 120. Specifically, one surface (hereinafter, referred to as a bonding surface) 110S and 120S of the metal members 110 and 120 is brought into contact with each other, and a punch (not shown) is applied to each of the opposite surfaces. At this time, the metal members 110 and 120 are brought into contact with each other so that their center axes coincide with each other. Electrodes are connected to both punches, and a voltage is applied after the inside of the apparatus is evacuated.

  Along with energization, a predetermined pressure is applied between both punches by a pressurizing mechanism (not shown). After the temperature is raised to a predetermined temperature by a discharge plasma generated by energization for a certain time, the pressure is applied for a certain time. Thereby, the electrode material 200 is obtained.

  Then, the generated electrode material 200 is cut. Here, each of the metal members 110 and 120 is partially cut so as to form a conical electrode tip surface indicated by a broken line K. The metal member 110 cuts out portions other than the central portion 110T of the joint surface 110S, and the metal member 120 scrapes off the peripheral portion of the joint surface 120S. A cutting method, a cutting tool, or the like is performed by a conventionally known method or tool.

  The position of the cut surface indicated by the broken line K, that is, the position where the electrode outer peripheral surface is formed is the size of the metal member 110, the diameters D1 and D2 of the metal member 120 and the difference thereof, the inclination angle of the electrode outer peripheral surface, and the thickness of the metal member 110. It is determined according to. In particular, it is determined that at least the joining surface peripheral portion 110T of the metal member 110 is removed and the joining surface central portion 110C is left.

  The electrode material 200 after cutting is composed of a conical metal part 110, a part of which is a truncated cone and the other part is a columnar metal part 120. From the electrode tip part 20A and the body part 20B shown in FIG. A cathode 20 is formed.

  Thus, according to the present embodiment, the cathode 20 having the electrode tip portion 20A made of triated tungsten is bonded to the discharge lamp 10 by SPS bonding. In the SPS bonding process, a columnar metal member 110 made of tritated tungsten and a columnar metal member 120 that is pure tungsten and has a diameter D2 larger than the diameter D1 of the metal member 110 are joined via bonding surfaces 110S and 120S. Heating is applied and SPS bonding is performed. Thereafter, cutting is performed so that the cross section indicated by the broken line K is the outer peripheral surface of the electrode.

  The joining surface 110S of the metal member 110 containing a thorium component has a lower smoothness than the joining surface 120S of the pure tungsten metal member 120. The difference becomes more significant as the diameter increases. However, since the diameter D1 of the bonding surface 110A, which is smaller than the diameter D2 of the bonding surface 120, is relatively small, the effect is less likely to appear after solid-phase bonding, and a decrease in bonding strength can be suppressed.

  Further, due to the difference in physical properties with the metal members 110 and 120, a minute wedge portion that is not partially joined is formed along the direction perpendicular to the electrode axis in the vicinity of the joining surface end portion. In the present embodiment, by cutting the joining surface peripheral portion 110T of the metal member 110, the wedge formed on the joining surface peripheral portion 110T at the time of SPS joining can be removed. As a result, a decrease in bonding strength can be suppressed.

  In particular, the diameter D1 of the metal member 110 can be made closer to the diameter D2 of the metal member 120 by reducing the cutting portion of the metal member 110 as much as possible so as to remove only the wedge portion. This makes it possible to increase the applied pressure during SPS bonding and increase the bonding strength.

  On the other hand, when energized at the time of SPS bonding, the bonding strength at the central portion of the bonding surface becomes smaller than the bonding strength near the outer peripheral surface of the metal members 110 and 120 due to the skin effect. However, since the diameter D1 of the metal member 110 is relatively small, the influence of the skin effect is reduced. Moreover, the range which cuts the outer periphery vicinity of the metal member 110 with high joining strength becomes comparatively small. Therefore, compared with the case where contact surfaces having the same diameter are brought into contact with each other, the bonding strength at the center is increased.

  In the metal member 110 made of triated tungsten, there may be a portion where thorium dioxide does not exist near the surface. However, since the surface layer portion of the metal member 110 is removed by cutting after SPS bonding, it is possible to prevent arc discharge instability due to thorium dioxide deficiency. Furthermore, by performing the cutting process after the SPS bonding, there is no step in the bonding surface radial direction. As a result, no abnormal discharge occurs when the lamp is lit.

  The diameter of the metal member, the angle of inclination of the electrode tip surface, and the cross-sectional shape of the tip surface are arbitrary, and it is cut so as to have a flat outer peripheral surface without a step to form a tapered electrode tip. It is possible. Also, the material and shape of the metal member are arbitrary, and it is possible to configure the solid member so that an emitter other than thorium is contained in the electrode tip, and the material other than the metal member (ceramic, carbon, etc.) It is also possible to constitute the body part. Furthermore, you may comprise the electrode front-end | tip part so that both emitter containing members, such as triated tungsten, and the solid member of a trunk | drum part may be included.

  Next, the discharge lamp which is 2nd Embodiment is demonstrated using FIG. In the second embodiment, a cathode is formed by joining three metal members. Other configurations are substantially the same as those in the first embodiment.

  FIG. 4 is a diagram illustrating a cutting process according to the second embodiment.

  In 2nd Embodiment, the electrode raw material 300 is shape | molded by carrying out SPS joining of the cylindrical metal members 210,220,230. At this time, it joins so that the axis | shaft of each member may correspond. The metal member 210 is made of triated tungsten, and the metal members 220 and 230 are made of pure tungsten.

  The diameters J1 and J2 of the metal members 210 and 220 are equal, and the diameter J3 of the metal member 230 is larger than the diameter J2 of the metal member. And the cut surface K equivalent to an electrode outer peripheral surface is defined as shown in FIG. Specifically, the metal member 220 is cut so that the vicinity of the outer peripheral edge 220T on the joint surface S2 is deleted, and the metal member 210 is cut so that only the central portion 210C on the joint surface S1 remains.

  As a result, the cathode 20 'is formed. The joining surfaces S1 and S2 of the electrode tip portion 20A 'are diffusion-bonded, and there is no step in the radial direction. The ratio of the electrode body 20B 'is large. Note that the metal member 220 may be formed of a metal member containing triated tungsten.

10 Discharge lamp 20 Cathode 110 Metal member (solid end member)
120 Metal member (fuselage solid member)
S joint surface

Claims (9)

Column-shaped body solid comprising at least a part of the electrode tip portion and containing an emitter, and a column-shaped body solid comprising at least an electrode body portion and having a joining surface having a diameter larger than the joining surface of the tip solid member The members are solid-phase bonded through each other's bonding surface,
A method for manufacturing an electrode for a discharge lamp, comprising: cutting an electrode material generated by solid phase bonding so as to form a tapered electrode tip. A columnar tip solid member that constitutes at least a part of the tip of the electrode and contains an emitter, and a columnar intermediate solid member that has a joint surface having the same diameter as the joint surface of the tip solid member are connected to each other through the joint surface. Solid phase bonding, and
The intermediate solid member has a bonding surface having a diameter larger than the bonding surface of the intermediate solid member, and at least the columnar body solid member constituting the electrode body portion is solid-phase bonded through each other bonding surface,
A method for manufacturing an electrode for a discharge lamp, comprising: cutting an electrode material generated by solid phase bonding so as to form a tapered electrode tip.   3. The method for manufacturing an electrode for a discharge lamp according to claim 1, wherein in the electrode material, at least a peripheral portion of a joint surface between the tip solid member and the body solid member is cut.   4. The discharge lamp according to claim 1, wherein the electrode material is cut so as to remove a wedge portion formed on a peripheral portion of the joint surface of the tip solid member. Electrode manufacturing method.   5. The method of manufacturing an electrode for a discharge lamp according to claim 1, wherein the electrode material is cut so as to leave only a central portion of the joint surface of the tip solid member.   2. The discharge lamp according to claim 1, wherein a ratio of a diameter of the joining surface of the front solid member and a diameter of the joining surface of the body solid member satisfies 0.05 <D1 / D2 <1. Electrode manufacturing method.   The method for manufacturing an electrode for a discharge lamp according to any one of claims 1 to 6, wherein the tip solid member is made of triated tungsten.   8. The method for producing an electrode for a discharge lamp according to claim 1, wherein SPS bonding is performed as solid phase bonding. A columnar tip solid member that constitutes at least a part of the tip of the electrode, and an intermediate solid member having a joint surface having the same diameter as the joint surface of the tip solid member are solid-phase joined via each other joint surface, and ,
The intermediate solid member has a bonding surface having a diameter larger than the bonding surface of the intermediate solid member, and at least the columnar body solid member constituting the electrode body portion is solid-phase bonded through each other bonding surface, Cutting the electrode material generated by solid-phase bonding to form a tapered electrode tip
A method for producing an electrode for a discharge lamp.

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