KR20080037566A - Electrode for cold cathode fluorescent lamp - Google Patents

Abstract

An electrode for a cold cathode fluorescent lamp is provided to extend the lifespan of the electrode by utilizing spots made of alloy having tungsten and molybdenum. Spots, whose whole combination includes 5 to 83 weight percent molybdenum and tungsten, are made of molybdenum alloy including the tungsten and tungsten alloy including the molybdenum. The ratio of density of the spots is 80 to 96 percent. The whole combination further includes 0 to 5 weight percent nickel. The spots are formed by 3 to 10mum of an average crystal grain size and less than 20mum of a maximum crystal grain size.

Description

Electrode for cold cathode fluorescent lamp {ELECTRODE FOR COLD CATHODE FLUORESCENT LAMP}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold cathode fluorescent lamp used for a light source for illumination, a backlight for a monitor of a PC, a liquid crystal TV for a car navigation system, a liquid crystal display for a car navigation system, and the like, and more particularly to an electrode for a cold cathode fluorescent lamp suitable for this.

As shown in FIG. 1, the cold cathode fluorescent lamp has a structure in which the electrodes 3 connected to the outside through the terminals 2 are arranged at both ends in the glass tube 1, and the inner surface of the glass tube 1 is provided. The phosphor 4 is coated on the substrate, and the sealing gas 5 made of a rare gas and a small amount of mercury is sealed. A high electric field is applied to the electrodes 3 at both ends to generate a glow discharge in the low-pressure mercury vapor, and the mercury excited by the discharge generates ultraviolet rays, and the ultraviolet light on the inner surface of the glass tube 1 4) is excited to emit light. As an electrode used here, the thing formed in the cylindrical shape with a bottom which can acquire a holocathode effect is used recently. In this case, the terminal 2 is attached to the bottom of the bottomed cylindrical electrode 3 by soldering or the like.

The cold cathode lamp having such a structure is recently used as a light source for a backlight of a liquid crystal display, and recently, it has also been applied to a liquid crystal display of a liquid crystal television, a car navigation system, and the like, and its demand is gradually increasing. In addition, the number of cold cathode fluorescent lamps used in one product is also approximately one in a liquid crystal display of 15 inches or less, but a plurality of cold cathode fluorescent lamps are used because the required luminance cannot be obtained in a large monitor or a television. As a result, demand is expanding rapidly.

Although the cold-cathode fluorescent lamp which demand is expanding as mentioned above, the following matter is calculated | required about a cold-cathode fluorescent lamp and the electrode used for it by the request of the performance improvement of a liquid crystal display etc.

(1) From the demand for thinner and lighter products, small diameters are required for cold-cathode fluorescent lamps, and consequently, further miniaturization is required for electrodes, and excellent molding is required.

(2) In liquid crystal displays, lower power consumption is required, and higher efficiency of cold cathode fluorescent lamps is required. Since the brightness of the lamp increases almost in inverse proportion to the diameter of the lamp, in addition to miniaturization, the application of a material having a higher electron emission property, that is, a material having a low work function and a low cathode drop voltage is required for the electrode.

(3) In a liquid crystal display or the like, one inverter is required for one lamp. For this reason, when a cold cathode fluorescent lamp becomes high brightness, the number of lamps used per liquid crystal display can be reduced, and a cost can also be reduced. Also from this point of view, high luminance is required for the cold cathode fluorescent lamp, and application of a material having a low cathode effect voltage is required for the electrode.

(4) Since the life of a cold cathode fluorescent lamp is the product life of a liquid crystal display, a longer life is required for a cold cathode fluorescent lamp. For this reason, application of a material which is hard to be sputtered as an electrode is desired.

(5) In a liquid crystal display etc., even if competition of each manufacturer is fierce and it satisfy | fills the characteristics of said (1)-(4), since it does not hold as a product at high cost, it is desired that it is as low as possible.

As an electrode material for a cold cathode fluorescent lamp, nickel which has been easily processed and has a low price has been conventionally used. However, in the nickel electrode, when the discharge current is increased in order to increase the electron emission amount for higher luminance, the nickel electrode is in the tube. Sputtered by gas ions, the consumption of the electrode is intense and the life is shortened. In addition, an increase in the discharge current causes an increase in power consumption, and this also requires application to an electrode of a material having a lower cathode drop voltage instead of nickel.

Further, on the inner circumferential surface of the bottomed cylindrical nickel electrode, a material layer having a lower work function than nickel is provided, and an electron emission amount is increased (for example, Japanese Patent Application Laid-Open No. 10-144255 and See Japanese Patent Application Laid-Open No. 2002-289138). However, in such an electrode, a step of covering a material layer having a low work function is required, and since the base material of the electrode is nickel, it is easy to be worn, and recently, a product having a large bottom thickness has been introduced. Not all things are satisfied.

Attempts have also been made to apply molybdenum and tungsten to electrode materials as high melting point metals with low work function and no sputtering. Specifically, the electrode for cold cathode fluorescent lamps to which molybdenum is applied as the electrode material is formed by penetrating from a rolled plate of molybdenum into a cylindrical shape with a bottom by deep drawing, and having a higher melting point than nickel. Since it is excellent in discharge characteristics, it satisfy | fills the requirements of said (1)-(4).

However, the rolled sheet of molybdenum tends to be anisotropic or poor in ductility, so that plastic working is difficult, and the material yield is poor. Therefore, the rolled sheet of molybdenum does not satisfy the requirements for the above (5). In addition, since the ratio of the thickness of the cylindrical portion and the bottom portion is only about 1: 2 due to the limitation of the molding method, there is a limit in the degree of freedom in design of the shape. In addition, the application of tungsten to the electrode is not possible because the tungsten is hard and the ductility is insufficient, and the deep drawing process is impossible, and practical production cannot be achieved.

By the way, at the test sample level, a bottomed cylindrical electrode having one end opened by the above-described molybdenum or tungsten rolled plate was produced and subjected to a discharge test. It was recognized that. Molybdenum and tungsten are high melting point metals, but mercury vapor is less likely to reach the bottom of the electrode in a cylindrical electrode with an open end, and a rare gas discharge causes high temperature thermal history. This high-temperature thermal history causes coarsening of crystal grains called secondary recrystallization, and when the discharge current rises in the electrode showing such coarse crystal grains, the high melting point metal In spite of using, it was found that scattering of the material easily occurred due to sputtering and the above breakage occurred.

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

The electrode for cold cathode fluorescent lamps of the present invention is composed of a Mo alloy phase containing W and a Mo alloy phase containing W, and a total composition of Mo: 5 to 83% by mass, and the balance being unavoidable impurities and W. It shows a speckle-like structure, and is characterized by the density ratio of 80 to 96%.

Moreover, in the electrode for cold cathode fluorescent lamps of this invention, it is preferable that the whole composition further contains Ni more than 0 and 5 mass% or less, and the speckle structure has an average crystal grain diameter of 3-10 micrometers, and is maximum It is preferable that the crystal grain diameter is 20 micrometers or less.

According to the electrode for cold cathode fluorescent lamp of the present invention, by using molybdenum and tungsten having a high melting point, the molybdenum and tungsten are not completely alloyed, and the Mo alloy phase containing fine W is used. By forming a speckle-like structure composed of W alloy phase containing Mo, the coarsening of crystal grains called secondary recrystallization is suppressed even under an environment where high temperature thermal history is applied, and sputtering accompanying an increase in discharge current is achieved. It is possible to prevent the occurrence, thereby improving the product life of the electrode.

In the electrode for cold cathode fluorescent lamps of the present invention, high melting point molybdenum and tungsten, which are low in work function and made of sputtered tissue of different compositions, are used to provide high temperature without damaging the work function of the entire electrode. By preventing the secondary recrystallization of each phase by the thermal history, by sintering the following raw materials, the density ratio is 80 to 96%, the average grain size is 3 to 10㎛, the maximum grain size is 20㎛ or less, The spot-like structure which consists of a Mo alloy phase containing fine W and a W alloy phase containing Mo is formed.

The whole composition of the electrode for cold cathode fluorescent lamps of this invention is Mo: 5-83 mass%, and remainder is an inevitable impurity and W, The spot which consists of Mo alloy phase containing W and W alloy phase containing Mo In order to form a phase structure, it can obtain by sintering using molybdenum powder and tungsten powder as a raw material, and using the raw material powder which added 5-83 mass% molybdenum powder to tungsten powder. At this time, when Mo amount is less than 5 mass%, there will be too much W alloy phase, and the effect of the suppression of the coarsening of W crystal grain by a Mo alloy phase will become insufficient. On the other hand, when Mo amount exceeds 83 mass%, there will be too many Mo alloy phases, and the coarsening inhibitory effect of Mo crystal grain by a W alloy phase will become insufficient.

When the average grain size exceeds 10 µm and the maximum grain size exceeds 20 µm, the respective phases tend to be localized, and secondary recrystallization of the crystal grains easily occurs. Such fine crystal grains can be obtained by using 10 micrometers or less as a particle diameter of the molybdenum powder and tungsten powder used as a raw material. However, since the particle diameter which is less than 1 micrometer as a raw material powder becomes easy to fit in the gap of a metal mold | die, the powder of 1 micrometer or more is suitable for a raw material powder. In this case, the average grain size obtained after sintering is about 3 µm. From this, the range of 3-10 micrometers of average crystal grain diameters are suitable.

The electrode for cold cathode fluorescent lamps of the present invention can be obtained by sintering a raw material powder. In this case, the raw material becomes a surface having pores and irregularities derived from the metal powder, and is penetrated from the rolled plate and deeply drawn. As a result of the larger surface area compared to the molded one, the ionization effect is increased. In addition, since the pores remaining in the matrix suppress coarsening of the crystal grains by the pinning effect, the effect of preventing secondary recrystallization of each phase can also be obtained. However, if the density ratio exceeds 96%, the pores remaining in the sintered body will be insufficient, and the increase of the independent pores will result in insufficient effect of improving the ionization effect, and at the same time, the effect of preventing secondary recrystallization of each phase by the pores will be insufficient. It becomes close to what was shape | molded by the penetration from a rolling board and deep drawing. On the other hand, when the density ratio is less than 80%, the mechanical strength of the electrode becomes remarkable and weak, and breakage tends to occur at the time of handling in the subsequent lamp manufacturing process. From this, it is preferable that the electrode for cold cathode fluorescent lamps has a density ratio of 80 to 96%.

In the present invention, by containing a small amount of low melting point nickel, it is possible to reduce the sintering temperature without appropriately reducing the lifetime of the electrode and the discharge characteristics of the electrode, which is suitable. Nickel is easily added to molybdenum powder and / or tungsten powder in the form of nickel powder. That is, since Ni, which is added in the form of nickel powder, has a lower melting point than Mo or W, it dissolves during sintering and wets the surface of the molybdenum powder and tungsten powder to activate the surface, and the formation and growth of a neck between the powders is prevented. Promote. As the amount of nickel powder is increased, sintering can be performed at low temperature, and even if the sintering temperature is reduced to about 1450 ° C by addition of about 0.4% by mass, an electrode having a density ratio of 80% or more can be obtained, and thermal energy consumed in the sintering process can be obtained. At the same time, it is possible to reduce the wear and tear of the furnace. However, when the amount of Ni in the electrode for a cold cathode fluorescent lamp exceeds 5% by mass, a portion with high Ni concentration (Ni rich phase) appears on the surface of the electrode, and the area of molybdenum and tungsten decreases and the electron emission property decreases. Therefore, the amount of Ni in the electrode for cold cathode fluorescent lamps needs to be more than 0 and 5 mass% or less.

Moreover, although the electrode for cold cathode fluorescent lamps of this invention can be manufactured by a conventionally well-known method, For example, the raw material which attached the raw material powder with the quantity of binder etc. which were added more than the normal embossing method is used. It can manufacture suitably by the method of carrying out the shaping | molding using. Hereinafter, the manufacturing process by this method is demonstrated concretely.

In the above manufacturing method, it is required to flow a metal powder made of molybdenum powder and tungsten powder into the gap of the mold by using a small mold, so that a binder having a porosity or more at the time of tapping the metal powder is added to the metal powder and kneaded. It is desirable to. As addition amount of a binder, 40 volume% or more is suitable. If the amount of the binder is less than 40% by volume, the fluidity of the raw material becomes insufficient, and the uniform metal powder cannot be filled. On the other hand, when a binder is added more than 60 volume%, the subsequent binder removal process will be prolonged and will cause an increase in manufacturing cost. In addition, since the excess amount of binder is contained in the molded body, it is not possible to uniformly fill the metal powder, and at the same time, the shape stability in the debinding step and the sintering step is impaired, and mold deformation easily occurs. Therefore, it is preferable that the addition amount of a binder is 40-60 volume%.

Such a binder is more suitable if it consists of a thermoplastic resin and a wax. A thermoplastic resin is used in order to provide plasticity to a raw material, and polystyrene, polyethylene, polypropylene, polyacetal, polyethylene vinyl acetate, etc. are used. The wax prevents metal contact between the raw material, in particular metal powder, and the mold (including dice and punch) to realize uniform flow of the metal powder during press molding, and at the same time, to reduce friction between the molded body and the mold during extraction. In order to reduce and to extract easily, paraffin wax, urethane wax, carnauba wax, etc. are used. Thermoplastic resin and wax which have such an effect become a suitable binder, when comprised in the range of 20: 80-60: 40.

The raw material M is obtained by adding and kneading the binder to the metal powder composed of the above molybdenum powder and / or tungsten powder. This raw material M is shape | molded by the metal mold | die shown to FIG. 2A-2F. First, after filling a predetermined amount of raw material M into the die hole 14a of the die 14 (FIG. 2A), as shown to FIG. 2B and 2C, the raw material in the die hole 14a is formed into an electrode-shaped molded object. 1st punch (using the 1st punch 11 which forms the bottom part of the bottom part, the 2nd punch 12 which forms the inner diameter part of an electrode-shaped molded object, and the 3rd punch 13 which presses the opening cross section of an electrode-shaped molded object, 11) is fixed to the die 14, and the second punch 12 is pressurized to be pushed into the raw material, and the third punch 13 is molded while applying the back pressure to the raw material. In order to extract the obtained electrode shaped body 15, first, the 1st punch 11, the 2nd punch 12, and the 3rd punch 13 together with the electrode shaped body 15 from the die 14 upwards. It extracts (FIG. 2D), and then extracts the 2nd punch 12 upward from the electrode-shaped molded object 15 (FIG. 2E). Next, the 2nd, 3rd punches 12 and 13 are raised and separated from the electrode-shaped molded object 15 (FIG. 2F). In addition, what was described in FIG. 2B and 2C is shaping | molding by pushing back, You may raise the 1st punch 11 and push it forward. In this case, however, the molding of the raw material by applying the back pressure to the raw material by the third punch 13 is preferable since the height of the end of the electrode-shaped molded body can be molded uniformly and the density of the raw material becomes uniform in the molded body. .

In the above molding process, it is necessary to fill the gap of the fine mold by flowing the raw material, and therefore, the raw material needs to be heated to a temperature above the softening point of the thermoplastic resin contained in the binder prior to pressurization. If it does not heat or it is temperature which does not reach the softening point of a thermoplastic resin even if it heats, the fluidity | liquidity of a raw material will run out and a raw material cannot be filled uniformly and densely in the clearance gap of a metal mold | die. Moreover, it is more preferable to heat at the temperature more than melting | fusing point of the thermoplastic resin which the fluidity | liquidity of a raw material becomes the maximum. The heating may be performed after the heater is provided in the mold, and the raw material may be heated after being filled into the mold, or the raw material may be heated and supplied in advance.

The raw material may be granulated powder of a certain size so as to be handled by a general pressing method, and may be supplied using a filling method by a powder supply apparatus such as a feeder (powder box). However, since the die-shaped mold holes for forming the target electrode for cold cathode fluorescent lamps are minute, the granulated powder is uniformly and precisely when granulated to a size of powder suitable for the powder supply apparatus used in the general pressing method. It is difficult to charge 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. 2A, it is preferable to collect the quantity equivalent to one filling amount into one pellet of the size which fits into a mold hole, and to supply a raw material by a pellet unit. Moreover, when supplying a raw material by a pellet unit, even if a raw material is heated previously, since supply is easy, it is also preferable at this point.

Since the binder component contains 40-60 volume% of binder components obtained by the above, in order to remove this, the electrode-shaped molded body is heated to the thermal decomposition temperature of a binder component, and a binder removal process is performed. The binder is composed of a thermoplastic resin and a wax, but 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 rapidly gasify and expand, causing mold deformation of the molded body. It is necessary to slowly increase the temperature near the pyrolysis temperature of the wax. From this point of view, the binder removal process is once held near the sublimation temperature of the wax as a first step to remove the wax powder in the binder component, and then maintained again near the pyrolysis temperature of the thermoplastic resin as the second step to remove the thermoplastic resin powder. It is preferable to set it as the heating maintenance process of two steps. Moreover, since gas generation accompanying pyrolysis is performed gradually, it is preferable to mix | blend and use several things from which a thermoplastic resin and a wax differ in thermal decomposition temperature.

In the electrode-shaped molded body after the removal of the binder, the metal powders are not yet diffused and are not in a metallic bond, and are very weak. Here, sintering is performed in order to diffusely bond the metal powders to metals. As for sintering temperature, 1500 degreeC or more is suitable. Moreover, in the aspect containing Ni, 1450 degreeC or more of sintering temperature is preferable. In the sintering step, since the fine and small unevenness is used as the metal powder as described above, the contact area of the metal powder is large, whereby densification by sintering tends to proceed, and a dense sintered body having a density ratio of 80% or more at the above temperature is obtained. Lose. However, when the sintering temperature is below the lower limit of the temperature range, densification by sintering does not proceed, and only a low density and low strength sintered body can be obtained. On the other hand, when the sintering temperature exceeds 1800 ° C., the wear and tear of the furnace becomes severe. Therefore, the upper limit of the sintering temperature is preferably set to the above temperature. In the sintering atmosphere, the surface of the metal powder is oxidized or carbonized when oxygen or carbon is contained, so that sintering is difficult to proceed. When molybdenum is contained, the molybdenum powder occludes and expands hydrogen. It is necessary to use). In the 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 problem.

EXAMPLE

The particle diameters shown in Table 1 were prepared as molybdenum powder, tungsten powder and nickel powder. Moreover, what mixed polyacetal (softening point: 110 degreeC, melting | fusing point: 180 degreeC) and paraffin wax (softening point: 39 degreeC, melting | fusing point 61 degreeC) by the ratio of 4: 6 was prepared as a binder. These were combined and kneaded in the ratio shown in Table 1 to prepare a raw material, which was formed into pellets. The pellets were heated to 200 ° C and supplied to a mold heated to 140 ° C in advance, followed by compacting. After cooling to 40 ° C, extraction was performed to produce an electrode-shaped green compact. The obtained green compact was heated to 250 degreeC, hold | maintained for 60 minutes, and then temperature was raised again, hold | maintained at 450 degreeC for 60 to 120 minutes, and binder removal was performed. Subsequently, it hold | maintained for 60 minutes at the temperature shown in Table 1 in argon gas atmosphere, and sintering was performed. About the obtained electrode-shaped molded object, the elemental analysis by EPMA, the density ratio, and the average grain size by cross-sectional optical micrograph were measured. Moreover, the cold-cathode fluorescent lamp was assembled using the obtained electrode-shaped molded object, and the discharge voltage required in order to obtain 6 mA of discharge currents was measured under the distance between electrodes: 100 mm and the pressure of the sealed argon gas: 100torr. Furthermore, the sputter amount (hair loss amount) after continuously giving sputter discharge to the electrode for 5 hours by measuring discharge voltage DC3kV, discharge current 10mA, and distance between electrodes 50mm using argon gas pressure of 0.07torr using an electrode-shaped molded object, and measured molybdenum The case where the electrode which is 100% was evaluated by the index made into 100. The lower the sputtering index is, the lower the sputtering index is, indicating that a good electrode is obtained. These results are shown together in Table 1.

TABLE 1

In addition, about the sample numbers 05 and 09 of the obtained electrode-shaped molded object, it hold | maintained 60 to 120 minutes at 1400 degreeC in argon gas atmosphere, and the crystal grain growth test was done. These cross-sectional optical micrographs are shown in FIGS. 3A, 3B and 4A, 4B. 3A and 4A are before the crystal grain growth test, and FIGS. 3B and 4B are after the grain growth test.

The samples of Sample Nos. 01 to 09 in Table 1 are examples in which the influence of Mo content in the overall composition is investigated. In the samples of Sample Nos. 01 and 02 whose content of Mo is less than 5% by mass, the density ratio is 65% or less, no speckle structure defined in the present invention is formed, and the discharge voltage is also a large value exceeding 430V. , The sputtering index was also high, about 85 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, and the speckle structure defined in the present invention is not formed, and the discharge voltage is a large value exceeding 430V, The sputtering index was also a high value of about 90 or more. 3A and 3B, the growth of the crystal grain size was observed in Sample No. 05 of the present invention, whereas in Sample No. 09, the growth of the crystal grain size was observed from Figs. 4A and 4B. From these results, it was confirmed that content of Mo in the whole composition is 5-83 mass%, favorable discharge characteristics can be obtained and coarsening of a crystal grain size is suppressed. In this range, the discharge voltage for obtaining a discharge current of 6 mA is as low as 400 to 410 V and shows a good value, and the sputtering index also shows a good value of about 80 or less.

The sample numbers 05 and 10-13 of Table 1 are the examples which investigated the influence of the particle diameter of molybdenum powder and tungsten powder. In Sample Nos. 05 and 10 to 12 having a particle size of 10 µm or less, the density ratio, the maximum crystal grain size, the discharge voltage, and the sputtering index were good, whereas in Sample No. 13 having a particle size of 10 µm or more, the maximum crystal grain size was 23 µm. As a result, it is possible to obtain a fine specular structure, a large discharge voltage of 411 V, and a high sputtering index of 90. From these results, it was confirmed that a fine specular structure can be obtained at a particle diameter of the molybdenum powder and the tungsten powder of 10 µm or less, so that good discharge characteristics are exhibited. In this range, the discharge voltage is about 400 V and the sputtering index is about 80 or less, which shows good values.

The sample numbers 05 and 14-18 of Table 1 are the examples which investigated the influence of Ni content in the whole composition. In the samples of Sample Nos. 14 to 17 having a content of Ni of 5.0% by mass or less, even though the sintering temperature was lowered to 1450 ° C, the density ratio, the maximum grain size, the discharge voltage, and the sputtering index were good, but the content of Ni was 5.0% by mass. In the sample of Sample No. 18 exceeding, the density ratio was 97%, the maximum crystal grain size was 15 µm, the nickel rich phase was formed in the speckle phase structure, the discharge voltage was 460 V, and the sputtering index was 108, which was a high value. From these results, when content of Ni in the whole composition exceeds 0 and is 5.0 mass% or less, even if the sintering temperature is reduced, it is confirmed that a fine speckle structure is obtained and favorable discharge characteristics are exhibited. 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, which shows good values.

Sample numbers 05 and 19 to 23 in Table 1 are examples in which the influence of the density ratio was investigated. In Sample No. 19 having a sintering temperature of 1450 ° C., the density ratio was 71% and the discharge voltage was a large value of 450V. On the other hand, in the sample numbers 05 and 20-22 whose sintering temperature exceeds 1450 degreeC, a density ratio becomes 80 to 96%, the discharge voltage shows the favorable value of about 400-420V, and the sputtering index shows the favorable value of about 80 or less. . In Sample No. 23, the density ratio was 98%, the maximum grain size was coarsened to 50 µm, the discharge voltage was 435 V, and the sputtering index was 90, which was large. From these results, it was confirmed that favorable discharge characteristics are exhibited within the range of 80 to 96% of density ratio.

1 is a cross-sectional view showing the structure of a cold cathode fluorescent lamp.

2A to 2F are cross-sectional views showing a filling step, a press molding step, and an extraction step of suitably manufacturing the electrode for a cold cathode fluorescent lamp of the present invention.

3A and 3B are cross-sectional optical micrographs of the electrode for cold cathode fluorescent lamps of the present invention, where FIG. 3A is before the crystal grain growth test, and FIG. 3B is after the crystal grain growth test.

4A and 4B are cross-sectional optical micrographs of a conventional cold cathode fluorescent lamp electrode, in which FIG. 4A is before the crystal grain growth test, and FIG. 4B is after the crystal grain growth test.

<Explanation of symbols for main parts of the drawings>

11... First punch, 12... Second punch, 13... Third punch, 14... mold

Claims (3)

Mo: 5-83 mass%, and remainder are unavoidable impurities and W in the whole composition, and show the spot-like structure which consists of Mo alloy phase containing W and W alloy phase containing Mo, and density ratio is 80- It is 96%, The electrode for cold cathode fluorescent lamps characterized by the above-mentioned. The method according to claim 1, The said whole composition further contains Ni more than 0 and 5 mass% or less, The electrode for cold cathode fluorescent lamps characterized by the above-mentioned. The method according to claim 1 or 2, The speckle structure has an average crystal grain size of 3 to 10 µm and a maximum grain size of 20 µm or less.

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