Abstract:
The present invention discloses a structure of a PDP backplate and a fabrication method thereof which are capable of implementing a PDP having a high definition, high aspect ration and high luminance. The structure of a PDP backplate according to the present invention includes a metallic plate having a certain thickness, a plurality of barrier ribs arranged at a certain distance from each other on the metallic plate, an insulation layer formed on the wall surfaces of the barrier ribs and an upper surface of the metallic plate, a conductive layer formed on an upper surface of the insulation layer, a dielectric layer formed on a surface of the conductive layer, and a florescent layer formed on an upper surface of the dielectric layer.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a flat panel display apparatus, and in particular to a backplate of a PDP(Plasma Display Panel) has a high definition, a high aspect ratio, and a high luminance. 
     2. Description of the Background Art 
     Recently, a flat panel display apparatus such as a LCD(Liquid, Crystal Display), a FED(Field Emission Display) and a PDP(Plasma Display Panel) has been intensively studied. Among the above-described apparatuses, the PDP is easily fabricated because of its simple structure and has a high luminance and light emitting efficiency, a good memory function, and a wide view angle wider than 160°, so that the PDP is well applicable to a wide screen of more than 40 inches. 
     The construction of a surface discharge AC PDP of the conventional art will be explained with reference to FIG.  1 . 
     A front glass plate  10  and a back glass plate  20  are facing and distanced from each other, and a discharge region  30  which is defined by a corresponding barrier rib  23  is formed between the front glass plate  10  and the back glass plate  20 . 
     A plurality of address electrodes A are extended in a certain direction on the upper surface of the back glass plate  20 . A dielectric layer  22  is formed on the upper surfaces of the back glass plate  20  and the address electrodes A. 
     A plurality of barrier ribs  23  are formed on the upper surface of the dielectric layer between the address electrodes A. In addition, a fluorescent layer  24  is coated on both walls of each barrier rib  23  and on the upper surface of the dielectric layer  22  which covers the address electrodes A. 
     A sustain and display electrode Xn and a scan electrode Yn are spaced-apart in a parallel direction perpendicular to the direction of the address electrodes A on one surface of the front glass plate. The sustain and display electrode Xn is formed of a transparent ITO(lndium Tin Oxide), so that light passes through the same. Therefore, the sustain and display electrode is called as a transparent electrode. Bus electrodes  13  are formed at the end portions of the sustain and display electrode Xn and the scan electrode Yn for applying a stable driving voltage. The bus electrode  13  is formed of an aluminum or chrome/copper/chrome layers. In addition, a dielectric layer  14  which is formed of a PbO group material covers the sustain and display electrode Xn, the scan electrode Yn, the bus electrode  13  and the front glass plate  10 . MgO is coated on the surface of the dielectric layer  14  as a protection film  15 . The MgO protection film protects the PbO dielectric layer from a sputtering of ions and has a relatively higher secondary electron generating coefficient characteristic when an ion energy collides with the surfaces during a PDP plasma discharge and decreases a driving and sustaining voltage of the discharge plasma. 
     As shown in FIG. 1, He, Ne, Ar or a mixed gas of the same and a mixed gas of Xe  31  are filled in a discharge cell surrounded by the barrier rib of the PDP. The region between the barrier ribs becomes a discharge region  30 , namely, a discharge cell  30  for generating a discharge therein. 
     In the PDP, a plasma discharge is generated in the discharge region  30  by applying a certain voltage to the transparent electrodes. As an infrared ray generated by the plasma discharge excites the fluorescent layer formed on the backplate for thereby generating a visual ray. The thusly generated visual ray is made incident onto the front plate for thereby displaying a certain character or graphic. Therefore, the front plate is used as a plate for displaying graphics, and the backplate is used for generating visual light. 
     As described above, the PDP apparatus includes a plurality of discharge cells which are physically separated from each other by the barrier ribs. In order to fabricate a PDP apparatus having a lot amount of pixels using the same area panel, a plurality of discharge cells are required. However, when decreasing the size of the discharge region in order to increase the number of discharge cells, the discharge efficiency is decreased. Therefore, in a state that a certain size of the discharge region is maintained, in order to manufacture a large number of discharge cells, a higher and thicker barrier rib is required. A method for satisfying the above-described requirements has been intensively studied. The conventional barrier rib fabrication method will be explained with reference to FIGS. 2 through 4. 
     First, a fabrication method of a barrier rib based on a screen print method will be explained with reference to FIGS. 2A through 2C. 
     As shown in FIG. 2A, a dielectric film  201  is formed on an upper surface of a glass plate  200 . Next, a screen(not shown) having a pattern for fabricating a barrier rib is prepared on an upper surface of the glass plate  200 . An insulation paste is coated on the screen using a roller, etc. and is dried for thereby forming a first insulation paste pattern  202  as shown in FIG. 2 a.  Thereafter, the screen is prepared thereon again, and an insulation paste is coated and then dried. The above-described operation is repeatedly performed, so that a second insulation paste pattern  203  is stacked on the first insulation paste pattern  202  as shown in FIG. 2 b.    
     Next, the screen print method is repeatedly performed until the entire height of the stacked insulation paste pattern becomes 150˜200 μm for thereby forming a barrier rib  204  as shown in FIG.  2 C. 
     The above-described barrier rib fabrication method based on the screen print method is simple, and the cost of the same is low. However, it is needed to adjust the position of the plate and the screen at every time when performing the screen print process. In addition, a certain small misalignment may occur when adjusting the positions of the screen and plate in the repeated screen print processes, it is difficult to fabricate an accurate barrier rib and high definition barrier rib. In addition, since the above-described print and dry processes are repeatedly performed, a fabrication time is too extended. 
     As another conventional barrier rib fabricating method, there is a sand blasting method. The above-described sand blasting method will be explained with reference to FIGS. 3A through 3E. 
     Next, as shown in FIG. 3A, an insulation paste  301  is formed on a glass plate  200  by a thickness of 150˜200 μm. 
     Next, as shown in FIG. 3B, a photosensitive film  302  is formed on the insulation paste  301 . The photosensitive film  302  is formed in a tape shape by adding an organic material to a photosensitive slurry at a certain ratio and is stack-formed on the insulation paste. 
     The photosensitive film  302  is patterned by a photolithography method for thereby forming a photosensitive film pattern  302   a  as shown in FIG.  3 C. 
     As shown in FIG. 3D, the insulation paste  301  is etched by spraying an alumina or silica particle(polishing material) using the photosensitive film pattern  302   a  as a mask. 
     Thereafter, the photosensitive film pattern  302 a is removed for thereby forming a barrier rib  301   a  as shown in FIG.  3 E. 
     In the barrier rib fabrication method based on the sand blasting method, it is possible to form a barrier rib on a large area plate and to implement a high definition. However, since a lot amount of pastes which are removed by a polishing material is required, and the fabrication cost is high. In addition, since a physical impact is applied to the plate during the fabrication process, a crack may occur at the plate during the molding operation of the insulation paste. 
     As another conventional barrier rib manufacturing method, an additive method will be explained with reference to FIGS. 4A through 4E. 
     As shown in FIG. 4 a , a photosensitive film  401  is formed on a glass plate  400 . The above-described photosensitive film may be formed in a dry film shape and is attached on the glass plate. The photosensitive film may be formed is such as manner that a photosensitive resin is coated using a spin cotter. 
     Next, the photosensitive film  401  is patterned based on a photolithograph method using a light exposing mask for thereby forming a photosensitive film pattern  402  as shown in FIG.  4 B. 
     As shown in FIG. 4C, an insulation paste  403  is filled between the photosensitive film patterns  402 . 
     As shown in FIG. 4 d,  the photosensitive film pattern  402  is removed, so that only the insulation paste  403  remains on the glass plate. 
     The above-described processes of FIGS. 4A through 4D are repeatedly performed, so that a barrier  404  having a height of 150˜200 μm is formed as shown in FIG.  4 E. 
     In the additive method for fabricating a barrier rid, it is possible to fabricate a barrier rib having a fine width and a large size area plate. However, in this method, if the height of the barrier rib exceeds 10□m, it takes long time to coat the pattern. In addition, since the insulation paste and photosensitive film are repeatedly patterned and removed for fabricating the barrier rib, a certain residual material of the insulation paste and photosensitive film may remain. In addition, the pattern may be deformed, and a crack may occur at the barrier rib. 
     Another conventional barrier rib fabrication method will be explained with reference to FIGS. 5A through 5D. 
     As shown in FIG. 5A, a barrier rib material layer  501  is formed on an upper surface of a glass plate  500  to have a thickness(for example, 150˜200 μm). The barrier rib material layer is formed by coating an insulation paste or attaching a green tape. 
     As shown in FIG. 5B, a mold  503  having a groove  502  is prepared at a portion in which a barrier rib is formed on the barrier rib material layer  501 . 
     Next, a certain pressure is applied and stamped, and then as shown in FIG. 5C, a barrier rib material is filled into the groove  502 . 
     Thereafter, the mold  503  is removed for thereby forming a barrier rib  505  as shown in FIG.  5 D. 
     However, in the above-described stamping method, in order to fill a barrier rib material into the mold, a certain pressure is required. In addition, a uniform pressure must be applied to the mold. If the pressure is not uniform, the barrier rib may not have the same height. In addition, as the barrier rib is highly defined, it is impossible to separate the mold and the barrier rib material layer after the barrier rib material is filled in the mold. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide a backplate for a PDP(Plasma Display Panel) which is capable of providing a backplate of a PDP using an easily etched metallic material. 
     It is another object of the present invention to provide a structure of a PDP backplate which has an excellent heat transfer characteristic and heat radiating characteristic. 
     To achieve the above object, there is provided a backplate for a PDP according to a first embodiment of the present invention which includes a metallic plate having a certain thickness, a plurality of barrier ribs formed by etching the metallic plate, and an insulation formed on the wall surfaces of the barrier ribs and on an upper surface of the metallic plate. 
     To achieve the above object, there is provided a backplate for a PDP according to a second embodiment of the present invention which includes a metallic plate having a certain thickness, a plurality of barrier ribs arranged at a certain distance from each other on the metallic plate, an insulation layer formed on the wall surfaces of the barrier ribs and an upper surface of the metallic plate, a conductive layer formed on an upper surface of the insulation layer, a dielectric layer formed on a surface of the conductive layer, and a florescent layer formed on an upper surface of the dielectric layer. 
     Additional advantages, objects and features of the invention will become more apparent from the description which follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein: 
     FIG. 1 is a view illustrating the construction of a conventional PDP; 
     FIGS. 2A through 2C are cross-sectional views illustrating a screen print method as one example of a conventional barrier rib structure fabrication method; 
     FIGS. 3A through 3E are cross-sectional views illustrating a sand blasting method as another example of a conventional barrier rib structure fabrication method; 
     FIGS. 4A through 4E are cross-sectional views illustrating an additive method as another example of a conventional barrier rib fabrication method; 
     FIGS. 5A through 5D are cross-sectional views illustrating a stamping method as another example of a conventional barrier rib structure fabrication method; 
     FIG. 6 is a cross-sectional view illustrating a backplate structure according to the present invention; and 
     FIGS. 7A through 7F are cross-sectional views illustrating a backplate fabrication method according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A backplate and a fabrication method of the same according to the present invention will be explained with reference to the accompanying drawings. 
     FIG. 6 is a cross-sectional view illustrating a back structure according to the present invention. A backplate  600  includes a metallic plate  601  having a certain thickness, and a plurality of metallic protrusions  602  which are formed on an upper surface of the metallic plate  601  at a regular distance. In addition, there is provided a thermal expansion coefficient sustaining layer  603  attached on a lower surface of the metallic plate  601 . The metallic protrusions  602  become a barrier rib  602  for physically separating each discharge cell. In addition, the thermal expansion coefficient sustaining layer  603  maintains an approximate difference of a thermal expansion coefficient between the front and backplates of the PDP. Since the backplate of the present invention is formed of a metallic material, there is a difference in the thermal expansion coefficient with a glass used as a material of the front plate of the PDP. Therefore, when fabricating the PDP by bonding the metallic backplate and front plate, the backplate and the front plate may be separated from each other due to a different thermal expansion during the operation of the PDP. Therefore, the difference of the thermal expansion coefficients of the front plate and backplate is decreased by attaching a thermal expansion coefficient sustaining layer  603  formed of a glass or a glass-ceramic material, which has the same thermal expansion coefficient as that of the material of the front plate of the PDP or is similar to that of the material of the front plate of the PDP, on the lower surface of the metallic plate  601 . 
     In addition, An insulation layer  605  is formed on a wall surface of the metallic protrusion  602 , namely, the barrier  602  and on an upper surface of the metallic plate  601 , namely, at an inner wall of the discharge cell  604 . Each discharge cell  604  is electrically insulated by the insulation layer  605 , so that each discharge cell  604  is independent to each other. In addition, an electrode layer  606  formed of a conductive material is formed on a surface of the insulation layer  605 . The electrode layer  606  corresponds to an address electrode. A dielectric layer  607  is formed on an upper surface of the electrode layer  606 . In addition, a fluorescent layer  608  is formed on a surface of the dielectric layer  607  of the discharge cell  604 . In the backplate of the PDP according to the present invention, as a back base plate, a metallic plate is used without using a glass compared to the conventional art. In addition, as a barrier rib, the metallic protrusions are used for separating each discharge cell. 
     The structure of the present invention will be explained with reference to FIGS. 7A through 7F. 
     First, as shown in FIG. 7A, a metallic plate  700  is prepared. A thermal expansion coefficient sustaining layer  701  is attached on a lower surface of the metallic plate  700 . The thermal expansion coefficient sustaining layer  701  is preferably formed of a glass or a glass-ceramic material. The material of the metallic plate  700  is selected from the materials which do not have a large difference with the thermal expansion coefficient of a glass which is a material of the front plate and have an excellent etching characteristic. In the present invention, as a material of the metallic plate  700 , a titanium Ti is used. In addition, the thickness of the metallic plate  700  is about 0.5 mm. Next, a photoresist film is formed on an upper surface of the metallic plate  700 , and a resultant structure is patterned based on a photolithography method for thereby forming a photoresist pattern  702 . At this time, the photoresist pattern formed at a portion in which the discharge cell is formed is removed for thereby exposing the upper surface of the metallic plate  700 . 
     As shown in FIG. 7B, the exposed metallic plate  700  is etched using a HF solution by a certain depth for thereby forming a trench  703 . The trench  703  becomes a discharge region, namely, a region in which the discharge cell is formed, so that a discharge occurs therein. The portion covered by the photoresist pattern  702  is not etched. The portion which is not etched becomes a metallic protrusion  704 . The metallic protrusions  704  become barrier ribs for physically separating the discharge regions, namely, the discharge cells. 
     As shown in FIG. 7C, an insulation layer  705  having a certain thickness is formed on an upper surface of the entire structure of FIG. 7B using a spray method. The thickness of the insulation layer  705  is preferably 5 μm. The insulation layer  705  is formed by spraying a mixed solution manufactured by mixing a glass powder having a diameter of about 1˜2 μm with an isopropylene alcohol. The insulation layer  705  electrically separate each discharge cell. 
     Next, as shown in FIG. 7D, a conductive material layer  706  is formed on an upper surface of the insulation layer  705 . The conductive material layer  706  preferably has a thickness of about 5 μm. The conductive material layer  706  is formed by a spray method by mixing silver powder with a solution in which a MEK(Methylethylketon), a binding agent and a plasticizer are mixed or by a sputtering method. 
     The conductive material layer is heat-treated for about  30  minutes at a temperature of about 400 C., so that burning organic components contained in the conductive material layer. At this time, a photoresist pattern  702  is formed on an upper surface of the barrier rib  704 . A major component of the photoresist pattern  702  is an organic material. Therefore, the metallic protrusions  702 , namely, the photoresist pattern  702  formed on the barrier rib  702  are burned and removed, so that the conductive material layer  706  formed on the upper surface of the photoresist pattern  702  is removed. Namely, as shown in FIG. 7E, as the photoresist pattern  702  and the conductive material layer  706  formed on the upper surface of the barrier ribs  704  are removed, the upper surfaces of the barrier ribs  704  are exposed. As a result, the conductive material layer is separated in both directions about each barrier rib  704  for thereby insulating the discharge cells, so that each discharge cell has an electrically separated structure. The conductive material layer which is formed to electrically insulating each discharge cell is called as an electrode layer  706   a.  Namely, the conductive material layer is partially removed by an organic burning process of the conductive material layer and by a lift-off method for thereby forming an electrode layer. Therefore, the process for patterning the electrode layer is omitted in the present invention, so that the process becomes simplified. 
     Next, as shown in FIG. 7F, a dielectric layer  807  is formed on a front surface of the structure as shown in FIG. 7E to have a thickness of about 12 μm by a spray method. The dielectric layer  807  is preferably formed of a glass material having a certain melting point higher by 50° C. compared to the material of the insulation layer  805 . Next, a fluorescent layer  808  is formed on a surface of the dielectric layer  807 , so that the fabrication of the backplate of the PDP according to the present invention is completed. 
     As described above, in the backplate structure and a fabrication method of the same according to the present invention, since the backplate is manufactured by an etching method using a metallic plate having an excellent etching characteristic, it is possible to implement a high definition and high aspect ratio of the PDP. In addition, since the metallic plate having a high heat conductivity operates as the back base plate of the PDP, a heat radiating effect is excellent, and a driving reliability of the PDP is enhanced during an operation of the PDP. In the present invention, it is possible to implement a low cost compared to the barrier rib manufacturing method which uses a conventional insulation paste. 
     Although the preferred embodiment of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as recited in the accompanying claims.