JP2008108579A - Electrode for cold cathode fluorescent lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bottomed cylindrical electrode for a cold cathode fluorescent lamp, wherein coarsening of crystal grains called secondary recrystallization is prevented even under an environment in which high temperature heat history is applied, to enhance discharge characteristics for realizing high luminance and low power consumption and a product life. <P>SOLUTION: Overall composition contains Mo: 5-83 mass%, and the remainder contains inevitable impurities and W, a porphyritic texture composed of a Mo alloy phase containing W and a W alloy phase containing Mo is formed, and their density ratio is 80-96%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cold cathode fluorescent lamp used for an illumination light source, a backlight of a personal computer monitor, a liquid crystal television, a liquid crystal display for a car navigation system, and the like. It is about.

  As shown in FIG. 1, the cold cathode fluorescent lamp has a structure in which electrodes 3 connected to the outside by terminals 2 are arranged at both ends in a glass tube 1. 4 and a sealed gas 5 composed of a rare gas and a small amount of mercury are sealed. A high electric field is applied to the electrodes 3 at both ends to generate a glow discharge in a low-pressure mercury vapor. The mercury excited by the discharge generates ultraviolet rays, and the ultraviolet rays on the inner surface of the glass tube 1 are excited by the ultraviolet rays. To emit light. In recent years, the electrodes used here are formed in a bottomed cylindrical shape capable of obtaining a hollow cathode effect. In this case, the terminal 2 is bonded to the bottom of the bottomed cylindrical electrode 3 by brazing or the like.

  In recent years, cold cathode lamps with such a structure have been used as a light source for backlights of liquid crystal displays, and recently, they are also applied to liquid crystal displays for liquid crystal televisions and car navigation systems, and the demand for them is increasing. Is expanding. Furthermore, the number of cold cathode fluorescent lamps used in one product is approximately one for a liquid crystal display or the like of 15 inches or less, but a plurality of cold cathodes cannot be obtained because the required brightness cannot be obtained for large monitors and televisions. A fluorescent lamp is used. For this reason, demand is growing rapidly.

Although it is a cold cathode fluorescent lamp whose demand is expanding as described above, the following matters are required for the cold cathode fluorescent lamp and the electrodes used therefor in order to improve the performance of liquid crystal displays and the like.
(1) Due to the demand for thinner and lighter products, cold cathode fluorescent lamps are also required to have a smaller diameter, and with this, electrodes are required to be further reduced in size. Is required to be excellent.
(2) Low power consumption is required for liquid crystal displays and the like, and high efficiency of cold cathode fluorescent lamps is required. In addition to the progress of miniaturization since the lamp brightness increases almost inversely with the lamp inner diameter, the electrode is made of a material having a higher electron emission property, that is, a material having a low work function and a low cathode fall voltage. Application is required.
(3) A liquid crystal display or the like requires one inverter per lamp. For this reason, if the brightness of the cold cathode fluorescent lamp is increased, the number of lamps used per liquid crystal display can be reduced and the cost can be reduced at the same time. From this point of view, it is required to increase the brightness of the cold cathode fluorescent lamp, and the electrode is required to be applied with a material having a low cathode effect voltage.
(4) Since the product life of the liquid crystal display is mainly caused by the life of the cold cathode fluorescent lamp, the cold cathode fluorescent lamp is required to have a longer life. For this reason, application of a material that is difficult to be sputtered is desired as the electrode.
(5) In liquid crystal displays and the like, the competition among manufacturers is intense, and even if the characteristics (1) to (4) are satisfied, they cannot be realized as a product at a high cost. It is desired.

  As an electrode material for a cold cathode fluorescent lamp, nickel that has been conventionally easy to process and has been inexpensive has been used. However, with a nickel electrode, if the discharge current is increased in order to increase the amount of electron emission for higher brightness, The nickel electrode is sputtered by the gas ions in the tube, and there is a problem that the life of the electrode is severely shortened. Further, the increase in the discharge current causes an increase in power consumption, and from this, the application to an electrode made of a material having a lower cathode fall voltage, which is changed to nickel, is demanded.

  Also, a material layer having a lower work function than nickel on the inner peripheral surface of a bottomed cylindrical nickel electrode to increase the amount of emitted electrons has been proposed (see, for example, Patent Documents 1 and 2). . However, such an electrode requires a process of coating a material layer having a low work function, and is easily worn out because the electrode base material is nickel. Recently, it has been commercialized by increasing the bottom thickness. Although these have appeared, they do not satisfy all of the above requirements.

  Furthermore, attempts have been made to apply molybdenum or tungsten to the electrode material as a high melting point metal that has a low work function and is difficult to be sputtered. Specifically, an electrode for a cold cathode fluorescent lamp using molybdenum as an electrode material is formed from a molybdenum rolled plate by punching-deep drawing into a bottomed cylindrical shape, which has a higher melting point and discharge characteristics than nickel. In order to be excellent, the above requirements (1) to (5) are satisfied.

  However, the rolled sheet of molybdenum is easily anisotropic and has poor ductility, so that it is difficult to perform plastic working, and further, the material yield is low, resulting in high costs. It does not meet. Further, only a ratio of the thickness of the cylindrical portion and the bottom portion of about 1: 2 can be obtained due to the limitation of the modeling method, and the design freedom of the shape is limited. In addition, application of tungsten to an electrode is difficult because of the fact that tungsten is hard and has poor ductility, so that deep drawing cannot be performed, and the mass production has not actually been achieved.

JP-A-10-144255 JP 2002-289138 A

  By the way, when a bottomed cylindrical electrode having one end opened with the above-mentioned molybdenum or tungsten rolled plate at the test sample level was subjected to a discharge test, a large breakdown thought to be caused by sputtering at the bottom of some electrodes. What showed a hole was recognized. As a result of investigating the cause, molybdenum and tungsten are refractory metals. However, in a bottomed cylindrical electrode with one open end, mercury vapor is difficult to reach the bottom of the electrode, resulting in a rare gas discharge and high temperature heat. A history was added, and this high-temperature thermal history caused crystal grain coarsening called secondary recrystallization, and in the electrode having such coarse crystal grains, when the discharge current increased, Despite the use of a melting point metal, it was found that the material was easily scattered by sputtering and the above destruction occurred.

  Therefore, the present invention prevents coarsening of crystal grains, which is called secondary recrystallization even in an environment where high-temperature thermal history is applied, and improves discharge characteristics and product life for higher brightness and lower power consumption. An object of the present invention is to provide a bottomed cylindrical cold cathode fluorescent lamp electrode.

  The electrode for the cold cathode fluorescent lamp of the present invention has an overall composition of Mo: 5 to 83% by mass, the balance being inevitable impurities and W, a Mo alloy phase containing W, and a W alloy phase containing Mo. And a density ratio of 80 to 96%.

  Further, in the cold cathode fluorescent lamp electrode of the present invention, it is preferable that the overall composition further includes Ni exceeding 0% by mass and not more than 5% by mass, and the patchy structure has an average crystal grain size of 3 to 10 μm. And the maximum crystal grain size is preferably 20 μm or less.

  According to the cold cathode fluorescent lamp electrode of the present invention, by using molybdenum and tungsten having a high melting point, the discharge characteristics are excellent, and molybdenum and tungsten are not completely alloyed. By forming a mottled structure consisting of a Mo alloy phase containing Mo and a W alloy phase containing Mo, the coarsening of the crystal grains, which is called secondary recrystallization, is suppressed even in an environment where high temperature thermal history is applied. Further, it is possible to prevent the occurrence of sputtering accompanying an increase in the discharge current, thereby improving the product life of the electrode.

  In the cold cathode fluorescent lamp electrode of the present invention, by using a high-melting molybdenum and tungsten having a low work function and difficult to be sputtered to form a patchy structure having different compositions, without impairing the work function of the entire electrode, This prevents secondary recrystallization of each phase due to high-temperature thermal history. By sintering the following raw materials, the density ratio is 80 to 96% and the average crystal grain size is 3 to 10 μm. And a patchy structure consisting of a Mo alloy phase containing fine W and a W alloy phase containing Mo and having a maximum crystal grain size of 20 μm or less is formed.

  The overall composition of the electrode for a cold cathode fluorescent lamp of the present invention is Mo: 5 to 83% by mass, and the balance is inevitable impurities and W, and consists of a Mo alloy phase containing W and a W alloy phase containing Mo. A mottled structure can be obtained by using a molybdenum powder and a tungsten powder as raw materials and sintering using a raw material powder obtained by adding 5 to 83% by mass of molybdenum powder to the tungsten powder. At this time, when the amount of Mo is less than 5% by mass, the W alloy phase becomes too much, and the effect of suppressing the coarsening of W crystal grains by the Mo alloy phase becomes poor. On the other hand, when the amount of Mo exceeds 83% by mass, the amount of Mo alloy phase increases so that the effect of suppressing the coarsening of Mo crystal grains by the W alloy phase becomes poor.

  When the average crystal grain size exceeds 10 μm and the maximum crystal grain size exceeds 20 μm, each phase tends to be unevenly distributed, so that secondary recrystallization of crystal grains is likely to occur. Such fine crystal grains can be obtained by using molybdenum powder and tungsten powder having a particle diameter of 10 μm or less as raw materials. However, a raw material powder having a particle size of less than 1 μm is likely to be caught in the gaps of the mold, so that a powder of 1 μm or more is suitable as the raw material powder. In this case, the average crystal grain size obtained after sintering is about 3 μm. Therefore, the average crystal grain is preferably in the range of 3 to 10 μm.

  The electrode for the cold cathode fluorescent lamp of the present invention can be obtained by sintering the raw material powder. In this case, the surface has pores and irregularities derived from the raw material being a metal powder, The ionization effect is increased as a result of the increased surface area as compared to those formed by punch-deep drawing. Moreover, since the pores remaining in the matrix suppress the coarsening of crystal grains by the pinning effect, the effect of preventing secondary recrystallization of each phase can be obtained. However, when the density ratio exceeds 96%, the pores remaining in the sintered body are scarce, and the effect of improving the ionization effect is poor due to the increase of independent pores, and secondary recrystallization of each phase by the pores. The effect to prevent becomes poor, and it becomes close to that formed by punching from a rolled plate-deep drawing. On the other hand, when the density ratio is less than 80%, the mechanical strength of the electrode is remarkably weakened, and breakage easily occurs during handling in the subsequent lamp manufacturing process. Therefore, the density ratio of the cold cathode fluorescent lamp electrode is desirably 80 to 96%.

  In the present invention, it is preferable to contain a small amount of nickel having a low melting point because the sintering temperature can be reduced without significantly reducing the life of the electrode and the discharge characteristics of the electrode. It is convenient to add nickel in the form of nickel powder to molybdenum powder and tungsten powder. That is, since Ni added in the form of nickel powder has a lower melting point than Mo and W, it melts during sintering and wets the surface of molybdenum powder and tungsten powder to activate the surface to form a neck between the powders, Promote growth. As the added amount of nickel powder increases, sintering becomes possible at a low temperature, and even if the sintering temperature is lowered to about 1450 ° C. by addition of about 0.4 mass%, an electrode having a density ratio of 80% or more can be obtained. As a result, the thermal energy consumed in the sintering process can be reduced, and the wear of the furnace can be suppressed. However, when the amount of Ni in the cold cathode fluorescent lamp electrode exceeds 5% by mass, a portion with a high Ni concentration (Ni-rich phase) appears on the electrode surface, and the area of molybdenum and tungsten decreases, resulting in electron emission. Sex is reduced. Therefore, the amount of Ni in the cold cathode fluorescent lamp electrode needs to exceed 0 and not more than 5% by mass.

  In addition, the cold cathode fluorescent lamp electrode of the present invention can be produced by a conventionally known method. For example, a mold using a raw material in which a raw material powder is provided with a larger amount of binder or the like than that provided by a normal pressing method is used. It can manufacture suitably by the method to shape | mold. Hereinafter, the manufacturing process by this method will be specifically described.

  In the manufacturing method as described above, since it is required to flow a metal powder composed of molybdenum powder and tungsten powder in the gap between the molds using a minute mold, the porosity is higher than the porosity when tapping the metal powder. It is preferable to add a binder to the metal powder and knead. The amount of the binder added is preferably 40% by volume or more. If the amount of the binder is less than 40% by volume, the fluidity of the raw material becomes insufficient and uniform metal powder filling cannot be performed. On the other hand, if the binder is added in excess of 60% by volume, the subsequent debinding process takes a long time and causes an increase in production cost. In addition, since the molded body contains an excessive amount of binder, the metal powder cannot be uniformly filled, and shape stability in the debinding process and the sintering process is impaired, and the mold is likely to be deformed. Therefore, it is preferable that the addition amount of a binder is 40-60 volume%.

  Such a binder is more preferably composed of a thermoplastic resin and a wax. The thermoplastic resin is used for imparting plasticity to the raw material, and polystyrene, polyethylene, polypropylene, polyacetal, polyethylene vinyl acetate, and the like are used. Wax prevents metal contact between raw materials, especially metal powder and molds (including dies and punches) to achieve uniform flow of metal powder during pressure molding, and molded body and mold during extraction It is added in order to reduce the friction between them and facilitate extraction, and paraffin wax, urethane wax, carnauba wax and the like are used. The thermoplastic resin and wax having such an action are suitable binders when configured in the range of 20:80 to 60:40.

  The raw material M is obtained by adding and kneading the binder to the metal powder composed of the molybdenum powder and the tungsten powder. This raw material M is formed by a mold shown in FIGS. First, after a predetermined amount of raw material M is filled in the die hole 14a of the die 14 (FIG. 2 (a)), the raw material in the die hole 14a is formed into an electrode shape as shown in FIGS. 2 (b) and 2 (c). The first punch 11 that forms the bottom of the molded body, the second punch 12 that forms the inner diameter part of the electrode-shaped molded body, and the third punch 13 that pressurizes the open end surface of the electrode-shaped molded body. 11 is fixed to the die 14, and the second punch 12 is pressed to be pushed into the raw material, and the third punch 13 is molded while applying a back pressure to the raw material. In order to extract the obtained electrode shape molded body 15, first, the first punch 11, the second punch 12, and the third punch 13 are extracted together with the electrode shape molded body 15 from the die 14 (FIG. 2D). Next, the second punch 12 is extracted upward from the electrode-shaped molded body 15 (e). Next, the second and third punches 12 and 13 are raised and separated from the electrode-shaped molded body 15 (f). In addition, although what was described in FIG.2 (b), (c) is shaping | molding by back extrusion, you may raise the 1st punch 11 and it may carry out forward extrusion. However, in any case, if the third punch 13 is formed while applying back pressure to the raw material, the height of the end of the electrode-shaped formed body can be formed uniformly, and the density of the raw material becomes uniform in the formed body. preferable.

  In the above molding step, since the raw material needs to flow and fill the gaps in the minute mold, the raw material is heated to a temperature equal to or higher than the softening point of the thermoplastic resin contained in the binder prior to pressurization. There is a need. If the temperature is not heated, or even if heated, the temperature does not reach the softening point of the thermoplastic resin, the flowability of the raw material is poor, and the raw material cannot be uniformly and densely filled in the gaps of the minute mold. Moreover, it is more preferable to heat to a temperature equal to or higher than the melting point of the thermoplastic resin that maximizes the fluidity of the raw material. This heating may be performed after a raw material is filled in the mold by installing a heater inside the mold, or the raw material may be heated and supplied in advance.

  The raw material may be supplied as a granulated powder of a certain size so as to be handled by a general stamping method using a filling method using a powder supply device such as a feeder (powder box). However, since the mold cavity of the mold for forming the target cold cathode fluorescent lamp electrode is very small, it is uniform and dense when granulated to a powder size suitable for a powder feeder used in a general mold method. It is difficult to fill the granulated powder. On the other hand, when the particle size of the granulated powder is reduced, the fluidity of the raw material powder is lowered, and it is difficult to adjust the granulated powder to a suitable size. For this reason, as shown in FIG. 2 (a), the raw material is packed in a single pellet of a size that fits into the mold cavity, and the raw material is supplied in pellet units. preferable. Moreover, when supplying a raw material by a pellet unit, since supply is easy even if it heats a raw material previously, it is preferable also from this point.

  Since the electrode-shaped molded body obtained as described above contains 40-60% by volume of the binder component, the electrode-shaped molded body is heated to the thermal decomposition temperature of the binder component in order to remove the binder component. Do. The binder is composed of a thermoplastic resin and a wax. However, if the temperature rise rate near the thermal decomposition temperature of the thermoplastic resin and the wax is high, the thermoplastic resin and the wax are rapidly gasified to expand and cause the molded product to lose its shape. Therefore, it is necessary to slowly increase the temperature at least near the thermal decomposition temperature of the thermoplastic resin and wax. From this point of view, the debinding step is temporarily held near the sublimation temperature of the wax as the first stage to remove the wax content in the binder component, and then held again near the thermal decomposition temperature of the thermoplastic resin as the second stage. It is preferable to use a two-stage heating and holding step for removing the thermoplastic resin component. Further, in order to gradually generate gas accompanying thermal decomposition, it is preferable to mix and use a plurality of thermoplastic resins and waxes having different thermal decomposition temperatures.

  In the electrode-shaped molded body after the binder is removed, the metal powders are not yet diffused and are not metallicly bonded, and are extremely brittle. Therefore, sintering is performed in order to diffusely bond metal powders in a metallic manner. The sintering temperature is suitably 1500 ° C. or higher. In the embodiment containing Ni, the sintering temperature is preferably 1450 ° C. or higher. In the sintering process, since the metal powder is fine and has less unevenness as described above, the contact area of the metal powder is large, so that densification by sintering is likely to proceed, and the density ratio is increased at the above temperature. A dense sintered body of 80% or more can be obtained. However, if the sintering temperature is below the lower limit of the above temperature range, densification by sintering does not proceed, and only a sintered body with low density and low strength can be obtained. On the other hand, if the sintering temperature exceeds 1800 ° C., the furnace becomes extremely worn out, so the upper limit of the sintering temperature is preferably set to the above temperature. Sintering atmosphere contains oxygen or carbon, which oxidizes or carbonizes the metal powder surface, making sintering difficult to proceed. If hydrogen is contained, molybdenum powder absorbs hydrogen and expands, so it is inert. It is necessary to use gas or a vacuum atmosphere (reduced pressure atmosphere). Further, in a reduced pressure atmosphere, in the case of a reduced pressure atmosphere having a pressure of 1 MPa or more, it is necessary to introduce an inert gas as a carrier gas to avoid the above problems.

  Molybdenum powder, tungsten powder and nickel powder having particle sizes shown in Table 1 were prepared. A binder prepared by mixing polyacetal (softening point: 110 ° C., melting point: 180 ° C.) and paraffin wax (softening point: 39 ° C., melting point 61 ° C.) in a ratio of 4: 6 was prepared. These were blended and kneaded in the proportions shown in Table 1 to prepare raw materials, which were formed into pellets. The pellets were heated to 200 ° C. and supplied to a mold heated in advance to 140 ° C. to perform compacting. After cooling to 40 ° C., extraction was performed to produce an electrode-shaped compact. The obtained green compact was heated to 250 ° C. and held for 60 minutes, then further heated and held at 450 ° C. for 60 to 120 minutes for debinding. Next, sintering was performed by maintaining the temperature shown in Table 1 for 60 minutes in an argon gas atmosphere. About the obtained electrode shape molded object, the elemental analysis by EPMA, the density ratio, and the average crystal grain diameter by a cross-sectional light micrograph were measured. In addition, a cold cathode fluorescent lamp was assembled using the obtained electrode shape molding, and the discharge voltage required to obtain a discharge current of 6 mA was measured under a distance between electrodes: 100 mm and a pressure of enclosed argon gas: 100 torr. Went. Further, the amount of spatter (amount of wear) after sputter discharge was continuously applied to the electrodes for 5 hours under the argon gas pressure of 0.07 torr using the electrode-shaped compact with a discharge voltage of DC 3 kV, a discharge current of 10 mA, and a distance between the electrodes of 50 mm. ) Was measured, and the index was set to 100 when the electrode was made of 100% molybdenum. The sputter index is an index indicating that the lower the sputtering index, the less the sputtering and the better the electrode. These results are also shown in Table 1.

  Further, the sample Nos. 05 and 09 of the obtained electrode-shaped molded bodies were subjected to a crystal grain growth test by being held at 1400 ° C. for 60 to 120 minutes in an argon gas atmosphere. These cross-sectional optical micrographs are shown in FIGS. In addition, (a) is a thing before a crystal grain growth test, (b) is a thing after a crystal grain growth test.

  Samples of sample numbers 01 to 09 in Table 1 are examples in which the influence of the Mo content on the overall composition was examined. In the samples of sample numbers 01 and 02 in which the Mo content is less than 5% by mass, the density ratio is 65% or less, the patchy structure defined in the present invention cannot be formed, and the discharge voltage is large exceeding 430V. The sputter index was as high as about 90 or more. On the other hand, in samples 08 and 09 in which the Mo content exceeds 83% by mass, the average crystal grain size is 15 μm or more, the spotted structure defined in the present invention cannot be formed, and the discharge voltage is a large value exceeding 430V. The sputter index was also a high value of about 90 or more. Further, from FIGS. 3 and 4, no growth of crystal grain size was observed in Sample No. 05 of the present invention, whereas growth of crystal grain size was observed in Sample No. 09. From these results, it was confirmed that the Mo content in the overall composition was 5 to 83% by mass, good discharge characteristics were obtained, and the coarsening of the crystal grain size was further suppressed. In this range, the discharge voltage for obtaining a discharge current of 6 mA is as low as about 400 to 410 V and shows a good value, and the sputtering index is also good as about 80 or less.

  Sample Nos. 05 and 10-13 in Table 1 are examples in which the influence of the particle size of molybdenum powder and tungsten powder was examined. Sample Nos. 05 and 10-12 having a particle size of 10 μm or less have good density ratio, maximum crystal particle size, discharge voltage, and sputtering index, whereas Sample No. 13 having a particle size exceeding 10 μm has a maximum It was shown that the crystal grain size was as large as 23 μm, a fine patchy structure was not obtained, the discharge voltage was as high as 460 V, and the sputtering index was as high as 90. From these results, it was confirmed that the particle diameters of the molybdenum powder and the tungsten powder were 10 μm or less, a fine patchy structure was obtained, and good discharge characteristics were exhibited. In this range, the discharge voltage is about 400 V, and the sputtering index is about 80 or less, indicating a good value.

  Sample Nos. 05 and 14 to 18 in Table 1 are examples in which the influence of the Ni content on the overall composition was examined. Samples Nos. 14 to 17 having Ni content of 2.0% by mass or less have good density ratio, maximum crystal grain size, discharge voltage, and sputtering index even when the sintering temperature is lowered to 1450 ° C. On the other hand, in the sample No. 18 in which the Ni content exceeds 5.0 mass%, the density ratio is 97%, the maximum crystal grain size is 15 μm, and a nickel-rich phase is formed in the patchy structure. As a result, the discharge voltage was 460 V and the sputtering index was 108. From these results, when the Ni content in the overall composition is more than 0 and 5.0% by mass or less, a fine patchy structure can be obtained even when the sintering temperature is lowered, and good discharge characteristics are obtained. It was confirmed that it was demonstrated. In this range, the discharge voltage for obtaining a discharge current of 6 mA is about 400 V, and the sputtering index is about 80 or less, indicating a good value.

  Sample Nos. 05 and 19 to 23 in Table 1 are examples in which the influence of the density ratio was examined. In sample number 19 where the sintering temperature was 1450 ° C., the density ratio was 71% and the discharge voltage was as high as 450V. On the other hand, in sample numbers 21 to 23 where the sintering temperature exceeds 1800 ° C., the density ratio is 80 to 96%, the discharge voltage is a good value of about 400 to 420 V, and the sputtering index is also a good value of about 80 or less. Show. In Sample No. 25, the density ratio was 98%, the maximum crystal grain size was coarsened to 50 μm, the discharge voltage was 435 V, and the sputtering index was 90, which was a large value. From these results, it was confirmed that good discharge characteristics were exhibited when the density ratio was in the range of 80 to 96%.

It is sectional drawing which shows the structure of a cold cathode ray lamp. It is sectional drawing which shows the filling process, pressure forming process, and extraction process which manufacture suitably the electrode for cold cathode ray lamps of this invention. It is a cross-sectional light micrograph of the electrode for cold cathode ray lamps of this invention, (a) is a thing before a crystal grain growth test, (b) is a thing after a crystal grain growth test. It is a cross-sectional light micrograph of the electrode for the conventional cold cathode ray lamp, (a) is a thing before a crystal grain growth test, (b) is a thing after a crystal grain growth test.

Explanation of symbols

11 ... 1st punch, 12 ... 2nd punch, 13 ... 3rd punch, 14 ... Die

Claims (3)

  The overall composition is Mo: 5 to 83% by mass, and the balance is inevitable impurities and W, and presents a patchy structure composed of a Mo alloy phase containing W and a W alloy phase containing Mo, and a density ratio is An electrode for a cold cathode fluorescent lamp, characterized by being 80 to 96%.   2. The cold cathode fluorescent lamp electrode according to claim 1, wherein the total composition further includes Ni of more than 0 and not more than 5 mass%.   3. The cold cathode fluorescent lamp electrode according to claim 1, wherein the patchy structure has an average crystal grain size of 3 to 10 μm and a maximum crystal grain size of 20 μm or less.

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