KR100570744B1 - MgO PELLET FOR A PROTECTION LAYER OF PLASMA DISPLAY PANEL AND THE MANUFACTURING METHOD THEREOF - Google Patents

Abstract

The present invention relates to an MgO pellet for a plasma display panel protective film and a method for manufacturing the same, and more particularly, to an MgO pellet used for a plasma display panel protective film with improved characteristics of an MgO protective film and a method for producing the same. To this end, the present invention is characterized in that the MgO pellets used in the plasma display panel protective film, having a rectangular parallelepiped shape. The MgO pellets of the present invention have advantages in that the production of MgO protective film can be increased by simple manufacturing and low processing cost, and by increasing the formation speed of the MgO deposited film and suppressing the splash phenomenon during the high-speed deposition.

MgO, Pellets, Shield, Cuboid

Description

MGO Pellets for Plasma Display Panel Protective Film and Manufacturing Method Thereof {MgO PELLET FOR A PROTECTION LAYER OF PLASMA DISPLAY PANEL AND THE MANUFACTURING METHOD THEREOF}

1 is a schematic enlarged view of a shape of an MgO pellet according to an embodiment of the present invention.

2 is a view schematically illustrating a process of forming an MgO protective film in a plasma display panel according to an experimental example of the present invention.

3 is a graph showing the discharge start voltage according to the MgO pellet volume in the experimental example of the present invention.

4 is an exploded perspective view of a discharge cell of a general plasma display panel.

The present invention relates to an MgO pellet for a plasma display panel protective film and a method for manufacturing the same, and more particularly, to an MgO pellet used for a plasma display panel protective film with improved characteristics of an MgO protective film and a method for producing the same.

A plasma display panel (PDP) is an apparatus for forming an image by a lower substrate by plasma discharge or a phosphor excited by discharge, and applies a predetermined voltage to two electrodes provided in a discharge space of the plasma display panel. Plasma discharge is caused to occur between them, and the phosphor layer formed in a predetermined pattern is excited by ultraviolet rays generated during the plasma discharge to form an image.

Such plasma displays are largely divided into AC type, DC type, and hybrid type. 4 is an exploded perspective view of a discharge cell of a typical AC plasma display panel. Referring to FIG. 4, a general plasma display panel 100 is formed on a lower substrate 111, a plurality of address electrodes 115 formed on the lower substrate 111, and a lower substrate 111 on which the address electrodes 115 are formed. A plurality of barrier ribs 123 and phosphor layers 125 formed on the surface of the barrier ribs 123 are formed on the dielectric layer 119 and on the dielectric layer 119 to maintain a discharge distance and prevent cross talk between cells. Include.

The plurality of discharge sustaining electrodes 117 are formed below the upper substrate 113 to be orthogonal to the plurality of address electrodes 115 formed on the lower substrate 111 at regular intervals. The dielectric layer 121 and the passivation layer 127 sequentially cover the discharge sustaining electrode 117. In particular, as the protective film 127, MgO, which is not only transparent to allow visible light to be transmitted well but also has excellent dielectric layer protection and secondary electron emission performance, is mainly used. Recently, research on a protective film made of different materials has been made. .

Here, the MgO protective film is a transparent protective thin film that serves to mitigate the effects of the ion bombardment of the discharge gas during the operation of the plasma display panel to protect the dielectric layer from ion collision and to lower the discharge voltage through the emission of secondary electrons. It is formed by covering the dielectric layer with a thickness of 3000 ~ 7000Å. MgO protective film is formed using sputtering method, electron beam deposition method, ion beam assisted deposition (IBAD), chemical vapor deposition (CVD), sol-gel method, etc. Recently, ion plating has been developed and used.

Here, the electron beam deposition method is a method of forming an MgO protective film by heating and evaporating the deposition material by colliding the electron beam accelerated by the electric and magnetic fields with the MgO deposition material. The sputtering method has advantages in that the protective film is more dense and advantageous in crystal orientation than the electron beam evaporation method. However, the sputtering method has a high cost in the manufacturing process. In the case of the sol-gel method, a MgO protective film is manufactured in a liquid phase.

The ion plating method has recently been attempted as an alternative to the various methods of forming the MgO protective film. In the ion plating method, the evaporated particles are ionized to form a film. The ion plating method has properties similar to the sputtering method with respect to the adhesion and crystallinity of the MgO protective film, but there is an advantage that deposition can be performed at a high speed of 8 nm / s.

Such MgO materials are used in the form of single crystals or sintered bodies. In the case of MgO single crystal material, there is a problem that quantitative control of a specific dopant is difficult due to the difference in solid solution limit due to the cooling rate during melting for deposition. To manufacture an MgO protective film by ion plating. MgO protective film evaporation materials are used in the form of pellets, and since the decomposition rate of MgO pellets varies according to the size and shape of the MgO pellets, there are significant differences in many aspects such as the deposition rate of MgO protective films. The method is being tried.

The present invention provides a method for producing MgO pellets that optimizes the physical properties of MgO pellets from MgO raw materials, and at the same time provides MgO pellets with optimized size and shape, thereby increasing the deposition rate of the MgO protective film and splashing phenomenon. To improve productivity.

The present invention for achieving the above object is characterized in that the plasma display panel protective film MgO pellets, having a rectangular parallelepiped shape.

In addition, the MgO pellets and its volume is preferably more than 3.5mm ³ 20.25mm less than ^3, preferably less than 7.0mm and more preferably ³ or more 14.0mm ^3.

In addition, the MgO pellets preferably have a cube shape.

And the steps of the present invention is a process for producing MgO pellets for a plasma display panel, a protective film, adding a doping material to the MgO raw material to prepare a Mg (OH) _2, and dried to a Mg (OH) ₂ to remove the adsorbed water, Calcining Mg (OH) ₂ to prepare MgO powder, mixing MgO powder with solvent and additives to prepare MgO slurry, spray drying MgO slurry to MgO granules, and compressing MgO granules And calcining the press-molded MgO granules.

The present invention also preferably further comprises the step of cutting the calcined MgO granules into a cuboid form.

On the other hand, in the step of firing the MgO granules, it is preferable to fire the MgO granules at a temperature of about 1700 ℃.

Hereinafter, with reference to the accompanying drawings an embodiment of the present invention will be described in detail.

The MgO pellets used for the protective film for plasma display panels of this invention are manufactured by the following method.

First, MgO raw material powder in powder form having 90.0 to 92.0% purity is prepared, and then Mg (OH) ₂ is prepared by adding a doping material to increase the purity to about 99.0%. Thus, to increase the purity of MgO it is made of Mg (OH) ₂ .

Mg (OH) ₂ thus prepared contains about 50.0% of moisture, and thus drying is required. Therefore, hot air is dried in a drying oven to remove the adsorbed water. After drying as described above, Mg (OH) ₂ was prepared as MgO powder by removing the crystal water by electrolysis and calcining in a bell type low temperature sintering furnace at a temperature of 2800 ° C. for about 60 hours. The molten MgO powder is cooled and then solidified again.

The solidified MgO powder is crushed using a breaker, and then a slurry is mixed by mixing a subsidiary material of a solvent and an additive. Mixing is carried out through a wet mill method, and as an auxiliary material, an anhydrous solvent having a reagent grade of 99.5% or more and an additive of Aldrich reagent are used. In wet mills, zirconia balls and urethane pots are used.

MgO granules are prepared by drying the mixed MgO slurry by spray drying using an explosion-proof spray dryer. In the granulation process, MgO powder having an average particle size of 3 to 5 μm is granulated and spherically formed at about 80 μm.

Next, MgO granules are press-molded using a rotary press. The compression-molded MgO granules are crystallized by sintering at a temperature of about 1700 ° C. in a high-temperature sintering furnace. When sintered at such a temperature, the surface of the MgO granules melts and adheres to the surface of other MgO granules, so that the MgO granules can be mutually bonded to each other. Thus, the density of the MgO granules itself increases, so that the pores are reduced, thereby forming an MgO protective film having a dense structure. There is an advantage.

Next, the sintered MgO granules are cut into a rectangular parallelepiped shape and used during the MgO protective film deposition process. As will be described in detail later, the present invention improves the deposition rate of the MgO film by cutting the MgO granules into a rectangular parallelepiped form and making the size constant.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic diagram showing an enlarged shape of an MgO pellet used in a plasma display panel protective film of the present invention.

As shown in Fig. 1, the MgO pellets used in the plasma display panel protective film of the present invention have a shape close to a rectangular parallelepiped. Fig. 1A shows MgO pellets whose shape is close to a cuboid, and Fig. 1B shows MgO pellets whose shape is close to a cube. As such, processing in the form of a rectangular parallelepiped is quite easy in many aspects, such as low processing cost and easy handling, because it is easy to process, and it is possible to suppress the splash phenomenon during high-speed deposition of MgO protective film by improving thermal shock resistance. There is an advantage.

FIG. 2 is a diagram schematically illustrating an experimental process for a cuboid-shaped MgO pellet of the present invention, and illustrates an electron beam deposition method schematically showing a process of forming an MgO protective film on a substrate on which electrodes and dielectric layers are sequentially formed. .

In the electron beam deposition method, a protective film is formed by colliding an electron beam accelerated by an electric field and a magnetic field with the deposition material to heat and evaporate the deposition material. In this case, high-speed deposition and high-purity deposition can be performed by concentrating the energy of the electron beam on the material surface. 2 is only an example of such a protective film forming step, and the protective film forming step is not limited to the electron beam evaporation method.

In the film forming process of the MgO protective film 17 shown in FIG. 2, the MgO protective film 17 is deposited while first moving the substrate 13 from the left side to the right side with the roller 21 and loading the vapor deposition chamber inlet 23. After that, it is discharged to the deposition chamber outlet 25 side. When there is an abnormality in the substrate 13, the substrate 13 can be unloaded from the vapor deposition chamber inlet 23. Since the inside of the deposition chamber 20 should be formed in a vacuum, a vacuum pump (not shown) is attached to continuously exhaust the gas, and the opening and closing is performed while double blocking the inside and the outside using the shutter 33. The electron gun 31 is operated to form a magnetic field and an electric field, and the ions discharged from the electron gun 31 are collided with the MgO pellet 27, which is a deposition material located below, to cause the MgO pellet 27 to be placed on the substrate 13. It is deposited on. MgO pellets 27 are used in the present invention prepared in the form of a cuboid. In the case of the MgO pellets 27 of the present invention, the MgO protective film is deposited while being cooled through the cooling device 29 because of the possibility of overheating due to ion collision.

In the present invention, the distance d between the electrodes is set to a certain degree between the discharge start voltage V _f at the time of discharge in the gas and the product pressure Pd between the gas pressure P and the distance d between the electrodes. The volume of MgO pellets suitable for MgO protective film formation was determined through experiments according to Paschen's Law that it would be difficult to discharge the following.

That is, according to Passen's law of Equation 1, the discharge start voltage V _f and Pd have the following relationship.

V _f = BPd / (K + lnPd)

Where B and K are constants.

While adjusting the pressure of the discharge gas, to obtain the optimum MgO volume by obtaining the discharge start voltage (V _f ) according to the volume of MgO according to the experimental example of the present invention.

In the deposition chamber 20 of the MgO protective film described above was tested as in the following experimental example. These experimental examples are only for illustrating the present invention, and the present invention is not limited thereto.

Experimental Example

After processing the MgO pellets in the form of a rectangular parallelepiped, the MgO protective film was formed in the MgO deposition chamber when MgO was deposited on the plasma display panel in which the dielectric was formed. In the deposition chamber, the basic pressure was 1 × 10 ^-4 Pa, the deposition formation pressure was 5.3 × 10 ^-2 Pa, and the substrate was brought to 200 ± 5 ° C. while supplying oxygen at 100 sccm (flow volume unit). Maintained. An MgO protective film was deposited by irradiating an electron beam through an electron gun adjusted to a current of 390 mA and a voltage of -15 kV DC. The discharge start voltage V _f was measured while changing the Pd value of the plasma display panel manufactured in this manner.

Experimental Example 1

MgO protective films were formed using MgO pellets having a volume of 1.5 mm ³ or more and less than 3.5 mm ³ as a deposition material. 3 shows a graph in which the discharge start voltage V _f is changed according to the Pd value.

Experimental Example 2

Except for using MgO pellets having a volume of 3.5mm ³ or more and less than 4.5mm ³ as the deposition material is the same as Experimental Example 1.

Experimental Example 3

Except that the volume is using the 4.5mm 7.0mm ³ or more than ³ MgO pellets as the evaporation material is the same as in Experimental Example 1.

Experimental Example 4

It is the same as Experimental Example 1 except using MgO pellet whose volume is 7.0 or more and less than 14.0 mm <^3> as a vapor deposition material.

Experimental Example 5

Except for using MgO pellets having a volume of 14.0mm ³ or more and less than 20.25mm ³ as the deposition material is the same as Experimental Example 1.

Experimental Example 6

It is the same as Experimental Example 1 except using MgO pellet whose volume is 20.25mm <^3> or less than 27.25mm <^3> as a vapor deposition material.

Table 1 summarizes the volume of the MgO pellets of Experimental Examples 1 to 6 described above.

3 is a view showing the discharge start voltage (V _f ) according to the Pd value in the volume of the MgO pellets used in the plasma display panel MgO protective film prepared through Experimental Example 1 to Example 6 as described above.

Comparing each of the experimental examples shown in Figure 3, when the Pd value is 2 or more in Experimental Example 1 and Experimental Example 6, it can be seen that the discharge start voltage (V _f ) gradually increases as the Pd value increases. Therefore, there is a difficulty in discharging. On the other hand, in the case of Experimental Examples 2 to 5, the discharge start voltage (V _f ) is relatively small, the discharge occurs relatively easily, it can be seen that the operating state of the MgO protective film of the plasma display panel is good. Considering these points, MgO pellets is suitable 20.25mm 3.5mm ³ or more by volume of less than about ^three for the Experimental Example 2 to Experimental Example 5.

In addition, it can be seen that also the bulk of the MgO pellets from the graph shown in FIG. 3 Experiment 4 the 7.0mm ³ or more is less than 14.0mm ^3, the discharge start voltage (V _f) is the smallest to the. Therefore, when the volume of the MgO pellets is 7.0 mm ³ or more and less than 14.0 mm ³ , the plasma display panel having the best discharge characteristics can be manufactured.

As described above, when the MgO pellets used for the MgO protective film of the plasma display panel have a rectangular parallelepiped shape, the manufacturing process is simple, so the process cost is low, and the thermal shock resistance is improved to improve the splash phenomenon during the high-speed deposition of the MgO protective film. It can suppress, and there exists an advantage that productivity improves.

Further, by the volume of the MgO pellets with 3.5mm ³ or more and less than 20.25mm ^3, it is possible to obtain a quality of the plasma display panel having a good MgO layer.

In particular, when the volume of the MgO pellets is made 7.0 mm ³ or more and less than 14.0 mm ³ , a plasma display panel having a more favorable MgO protective film can be manufactured.

MgO pellets can be prepared in the form of cubes to produce more diverse forms.

In the present invention, since the MgO powder raw material is manufactured via Mg (OH) ₂ , there is an advantage of further increasing the purity of the MgO powder.

On the other hand, the calcined MgO granules are used by cutting in the form of a cuboid, there is an advantage of easy manufacturing in the process.                     

In addition, since the MgO granules are calcined at a temperature of about 1700 ° C. when manufacturing the MgO pellets of the present invention, the MgO granules melt and adhere to other MgO granules so that the MgO granules can be bonded to each other. Since there is less, there is an advantage in that an MgO protective film having a dense structure can be formed.

Although the present invention has been described above, it will be readily understood by those skilled in the art that various modifications and variations are possible without departing from the spirit and scope of the claims set out below.

Claims (7)

MgO pellets used for plasma display panel (PDP) protective film, MgO pellets for a plasma display panel protective film having a rectangular parallelepiped shape. The method of claim 1, The MgO pellets MgO pellets for plasma display panel protective film having a volume of 3.5mm ³ or more and less than 20.25mm ³ . The method of claim 2, The MgO pellets MgO pellets for plasma display panel protective film whose volume is more than 7.0mm ³ but less than 14.0mm ³ . The method of claim 1, The MgO pellets MgO pellets for a plasma display panel protective film having a cube shape. As a method of manufacturing MgO pellets for plasma display panel protective film, Adding MgO material to the MgO raw material to prepare Mg (OH) ₂ ; Drying the Mg (OH) ₂ to remove adsorbed water; Calcining the Mg (OH) ₂ to prepare an MgO powder; Preparing a MgO slurry by mixing a solvent and an additive with the MgO powder; Spray drying the MgO slurry to form MgO granules; Compression molding the MgO granules; And Calcining the press-molded MgO granules; Method for producing a plasma display panel protective film MgO comprising a. The method of claim 5, The method for manufacturing a plasma display panel protective film MgO pellets further comprising the step of cutting the calcined MgO granules in a cuboid form. The method of claim 5, The firing of the MgO granules, the method of producing MgO pellets for a plasma display panel protective film for firing the MgO granules at a temperature of about 1700 ℃.

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