Patent Publication Number: US-2007113962-A1

Title: Method of manufacturing barrier rib structure for flat display panel

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATION  
      This application claims the benefit of Korean Patent Application No. 10-2005-0111444, filed on Nov. 21, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present embodiments relate to a method of manufacturing a barrier rib structure for a flat display panel, and more particularly to a barrier rib structure for a flat display panel, in which discharge cells are defined in a discharge space to prevent electrical and optical disturbances between adjacent discharge cells.  
      2. Description of the Related Art  
      The luminance and discharge efficiencies of plasma display panels (PDP) are major parameters for evaluating the performance of the plasma display panels. In particular, as the resolution of plasma display panels has greatly increased, the size of each discharge cell has reduced, thus reducing the surface area of a phosphor layer applied in the discharge cell. Therefore, it is harder to increase the luminance and discharge efficiencies of plasma display panels.  
      In general, a barrier rib structure of a plasma display panel is formed of a non-metal material such as PbO, B 2 O 3 , or SiO 2 . The current barrier rib structures that define discharge cells prevent electrical and optical disturbances between adjacent discharge cells but do not improve the luminance efficiency or the discharge efficiency of the panel.  
      However, it has been suggested that the luminance and discharge efficiencies of a plasma display panel can be improved by an effect known as the cavity effect, known as cathode discharge, which occurs when the barrier rib structure is formed of a metal material and a voltage of 0V is applied to the barrier rib structure. For example, there are papers disclosing “A Novel Shadow Mask PDP with High Luminance and Contrast” (SID (Society for Information Display) 03 DIGEST, pp. 149-151), “A Novel AC PDP with Shadow Mask” (SID 02 DIGEST, pp. 748-751), and “Three-Dimensional Investigation of a Novel Plasma Display Panel with Metal Barrier Plate” (SID 02 DIGEST, pp. 404-407).  
      It is known that a general etching process may be performed to manufacture a metal barrier rib structure. For example, to form the barrier rib structure on a rear substrate, a metal layer for the barrier rib structure is first deposited on the rear substrate, a screen mask is located on the metal layer for the barrier rib structure, and an etching solution is sprayed onto the screen mask to pattern the metal layer. In this case, electrodes and a dielectric layer may further be formed on the rear substrate.  
      The higher the resolution of panels, the narrower the interval between adjacent barrier ribs. However, to perform the etching process, the intervals between adjacent barrier ribs must be sufficient to be separated by the etching solution.  
      A large part of the metal layer applied onto the rear substrate, which does not become part of the barrier rib structure, is patterned and removed in the etching process, thereby increasing manufacturing costs.  
     SUMMARY OF THE INVENTION  
      The present embodiments provide a method of manufacturing a barrier rib structure for a flat display panel, which increases the luminance and discharge efficiencies of the flat display panel.  
      The present embodiments also provide a method of manufacturing a barrier rib structure for a high-definition flat display panel by using a metal material.  
      The present embodiments also provide a method of manufacturing a low-cost barrier rib structure for a flat display panel by using a metal material.  
      According to an aspect of the present embodiments, there is provided a method of manufacturing a barrier rib structure for a flat display panel, the method comprising preparing a base substrate; forming a photoresist layer on the base substrate, exposing a portion of the base substrate which is adhered to the photoresist layer, plating an upper surface of the exposed portion of the base substrate with a metal for the barrier rib structure, removing the photoresist layer to form the barrier rib structure, transferring the barrier rib structure onto a substrate, and forming a dielectric layer on at least a portion of an external surface of the transferred barrier rib structure.  
      According to another aspect of the present embodiments, there is provided a method of manufacturing a barrier rib structure for a flat display panel, the method comprising preparing a base substrate comprising at least an upper surface formed of a metal, forming a photoresist layer on the base substrate, exposing a portion of the base substrate which is adhered to the photoresist layer, plating an upper portion of the exposed portion of the base substrate with a metal for the barrier rib structure, removing the photoresist layer to form the barrier rib structure, transferring the barrier rib structure onto a substrate, and forming a dielectric layer on at least a portion of an external surface of the transferred barrier rib structure.  
      The metal for the barrier rib structure can be, for example, Cu, Al, Ni, Au, and Cr or a combination thereof.  
      After the removal of the photoresist layer, the method may further include separating the barrier rib structure from the base substrate, wherein the base substrate may be formed of a metal which is different from the metal for the barrier rib structure. In this case, the base substrate may be formed, for example, of a material containing Ni, and the metal for the barrier structure may include, for example, Cu.  
      Also, the step of exposing a portion of the base substrate may include positioning a photo mask on the photoresist layer and exposing the photoresist layer, and developing the photoresist layer.  
      Also, the method may further include performing pre-exposure baking after the forming of the photoresist layer of the base substrate, and performing post-exposure baking on the photoresist layer after the developing of the photoresist layer.  
      Also, the forming of the photoresist layer on the base substrate may comprising forming an adhesive layer on the base substrate; and forming the photoresist layer on the adhesive layer. In this case, the exposing of the portion of the base substrate may comprising removing a portion of the adhesive layer which corresponds to the exposed portion of the base substrate, and the removing of the photoresist layer may comprise removing the adhesive layer.  
      In certain embodiments, the adhesive layer is formed of amorphous Si.  
      In certain embodiments, the flat display panel is a plasma display panel. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other features and advantages of the present embodiments will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:  
       FIG. 1  is a flowchart illustrating a method of manufacturing a barrier rib structure for a flat display panel according to an embodiment;  
       FIG. 2  is a cross-sectional view explaining an operation of preparing a base substrate according to an embodiment, the operation being included in the method of  FIG. 1 ;  
       FIG. 3  is a cross-sectional view explaining an operation of forming a photoresist layer on the base substrate of  FIG. 2  according to an embodiment, the operation being included in the method of  FIG. 1 ;  
       FIG. 4A  is a cross-sectional view explaining an operation of performing an exposure process onto the photoresist layer according to an embodiment, the operation being included in the method of  FIG. 1 ;  
       FIG. 4B  is a cross-sectional view explaining an operation of developing the photoresist layer according to an embodiment, the operation being included in the method of  FIG. 1 ;  
       FIG. 5  is a cross-sectional view explaining an operation of electroplating an exposed upper portion of the base substrate with metal according to an embodiment, the operating being included in the method of  FIG. 1 ;  
       FIG. 6  is a cross-sectional view explaining an operation of removing the photoresist layer according to an embodiment, the operation being included in the method of  FIG. 1 ;  
       FIG. 7  is a cross-sectional view explaining an operation of separating a barrier rib structure from the base substrate according to an embodiment, the operation being included in the method of  FIG. 1 ;  
       FIGS. 8A through 8D  are photographs showing examples of a barrier rib structure manufactured according to an embodiment. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
      Hereinafter, a plasma display panel according to an embodiment will be described in greater detail with reference to the accompanying drawings.  
       FIG. 1  is a flowchart illustrating a method of manufacturing a barrier rib structure for a flat display panel according to an embodiment. Referring to  FIG. 1 , the method includes preparing a base substrate (S 10 ), forming a photoresist layer on the base substrate (S 20 ), exposing an upper surface of the base substrate (S 30 ), electroplating the exposed upper surface of the base substrate with metal (S 40 ), and removing the photoresist layer form the base substrate to obtain a barrier rib structure (S 50 ). The method may further include separating the barrier rib structure from the base substrate and transferring the separated barrier rib structure onto another substrate after the removal of the photoresist layer (S 60 ). Otherwise, a dielectric layer may be deposited onto at least a part of an exterior surface of the transferred barrier rib structure.  
      According to an embodiment, a high-definition barrier rib structure is manufactured by performing an exposure process and a developing process by using a photoresist layer to expose a location where a barrier rib structure is to be formed, and by electroplating the exposed location with metal.  
      In this case, at least an upper surface of or the entire part of the base substrate may assume the metal&#39;s properties, and thus, a metal layer for the barrier rib structure may be formed on the base substrate through electroplating. As will be described later, if electroplating is used, electroplating can be performed on only an exposed part of the base substrate. Therefore, a method of manufacturing a barrier rib structure for a flat display panel according to an embodiment will be described with respect to electroplating. However, the present embodiments are not limited to electroplating. For example, an exposed part of the base substrate through a gap in the photoresist layer can be plated with metal according to various electroless plating methods.  
       FIGS. 2 through 7  are cross-sectional views explaining the method of manufacturing a barrier rib structure for a flat display panel illustrated in  FIG. 1  according to some embodiments. The operations of the method of  FIG. 1  will now be described in greater detail with reference to  FIG. 1  through  FIG. 7 .  
      Referring to  FIG. 2 , a base substrate  10  is prepared (S 10 ). At least an upper surface  15  of base substrate  10  or the whole of the base substrate  10  may assume the metal&#39;s properties to charge the base substrate  10  with electricity during electroplating.  
      An adhesive layer  20  may be deposited on the base substrate  10 . The adhesive layer  20  is interposed between the base substrate  10  and a photoresist layer  30  of  FIG. 3 , which will be described later, to adhere the base substrate  10  and the photoresist layer  30  together. In particular, if the photoresist layer  30  is formed of a material such as SU-8 50 (Microchem Corp., Newton Mass.), the adhesive layer  20  is needed since it is difficult to adhere the photoresist layer  30  to the base substrate  10 . In this case, the adhesive layer  20  may be formed of amorphous Si.  
      Next, as illustrated in  FIG. 3 , a thick photoresist layer  30  is formed on the base substrate  10  (S 20 ) by using a spin coating method or various other methods.  
      The photoresist layer  30  contains foreign substances such as a solvent and water. Thus, after forming the photoresist layer  30 , pre-exposure baking may be performed on the photoresist layer  30  to remove such foreign substances.  
      Next, as illustrated in  FIGS. 4A and 4B , portions of the upper surface  15  of the base substrate  10  (upper surface  15  is not shown in  FIGS. 4A and 4B  and the adhesive layer  20  is exposed not the upper surface  15 ) adhered to the photoresist layer  30  are exposed (S 30 ). The exposed portions of the base substrate  10  will become cross-sections of the barrier rib structure, which will be described later. Thus, in operation S 30 , a photo mask  40  is positioned on the photoresist layer  30  and the photoresist layer  30  is exposed as illustrated in  FIG. 4A , and the photoresist layer  30  is developed as illustrated in  FIG. 4B .  
      Specifically, the photo mask  40  in which mask holes  42  having the same pattern as the shape of a barrier rib structure  50  of  FIG. 6  are formed, is positioned on the photoresist layer  30 , and an exposure process is performed on the photo mask  40  on the photoresist layer  30 . Exposed portions  32  of the photoresist layer  30  are removed through a developing process, and unexposed portions  31  of the photoresist layer  30  thereof that are blocked by the photo mask  40  are maintained even after the developing process.  
      If the adhesive layer  20  is deposited on the base substrate  10 , portions of the adhesive layer  20 , which correspond to the exposed portions  32  of the photoresist layer  30 , are preferably removed.  
      After performing the exposure process and the developing process on the photoresist layer  30 , post-exposure baking may be performed on the photoresist layer  30  to reduce residual stress of the photoresist layer  30  and improve the hardness thereof.  
      Next, as illustrated in  FIG. 5 , the exposed portion of the upper surface  15  of the base substrate  10  is plated with metal to form a barrier rib structure  50  (S 40 ) through electroplating if desired, in operation S 40 . That is, since at least the upper surface  15  of the base substrate  10  assumes the metal&#39;s properties, the base substrate  10  may be charged with electricity or exposed portions of the upper surface  15  of the base substrate  10  may be plated with the metal for the barrier rib structure  50  through electroplating. Also, unexposed portions of the base substrate  10  are adhered to the photoresist layer  30  and therefore are not plated with the metal.  
      In this embodiment, the metal for the barrier rib structure  50  may include at least one metal, examples of which are Cu, Al, Ni, Au, and Cr or combinations thereof. If the barrier rib structure  50  is comprised of at least one selected from the group, a cavity effect known as cathode discharge occurs therein, thus improving the luminance and discharge efficiencies of the flat display panel. That is, electrons are reflected onto a discharge space in the barrier rib structure  50 , plamsa electron are significantly increased to increase the plasma density, thereby improving the luminance and discharge efficiencies of the flat display panel. In particular, the high-definition barrier rib structure  50  manufactured according to an embodiment maximizes the cavity effect. In this case, UV-LIGA (Ultraviolet-Lithographie, Galvanoformung Abformung) technology may be used.  
      As will be described later, the metal barrier rib structure  50  may be separated from the base substrate  10  (S 60 ). In this case, the base substrate  10  is used as a base material for forming the barrier rib structure  50 . The formed barrier rib structure  50  is separated from the base substrate  10  and located on a front substrate or a rear substrate. The properties and shapes of the metal for the barrier rib structure  50  are preferably different from those of metal for the base substrate  10  so that the metal for the barrier rib structure  50  can be easily separated from the base substrate  10  due to stress between the barrier rib structure  50  and the base substrate  10 . In this case, the material for the upper surface  15  of the base substrate  10  (why not the entire base substrate  10 ) may contain Ni and the metal for the barrier rib structure  50  may contain Cu.  
      Next, as illustrated in  FIG. 6 , the photoresist layer  30  is removed (S 50 ). In operation S 50 , an exclusive stripper may be used or O 2  plasma etching may be performed to remove the photoresist layer  30 . However, the method of removing the photoresist layer  30  is not limited thereto.  
      If the adhesive layer  20  remains on the base substrate  10 , it is also removed in operation S 50 .  
      Next, as illustrated in  FIG. 7 , the barrier rib structure  50  may be separated from the base substrate  10  (S 60 ). The barrier rib structure  50  may be formed for each panel so that the entire barrier rib structure  50  can be separated from the base substrate  10  and combined with a substrate of the panel. In this case, the barrier rib structure  50  and the base substrate  10  are preferably formed of different metals.  
      The base substrate  10  may be a rear substrate of a plasma display panel, and in this embodiment, the barrier rib structure  50  need not be separated from the base substrate  10 .  
       FIGS. 8A through 8D  are photographs showing examples of the barrier rib structure  50  manufactured according to some embodiments.  FIG. 8A  shows a stripe type barrier rib structure manufactured according to an embodiment.  FIG. 8B  shows a box type barrier rib structure  50  according to an embodiment.  FIG. 8C  shows a fish-bone type barrier rib structure according to an embodiment.  FIG. 8D  shows a meander type barrier rib structure according to an embodiment. The examples of the barrier rib structure  50  shown in  FIGS. 8A through 8D  are high-definition barrier rib structures.  
      The flat display panel is preferably a plasma display panel, since according to the present embodiments, the plasma density can be increased by increasing the number of times that a plasma gas filled in a discharge space of the plasma display panel is discharged.  
      According to the present embodiments, a high-definition metal barrier rib structure can be formed to improve the luminance and discharge efficiencies of the flat display panel. According to the present embodiments, the plasma density of the flat display panel is increased.  
      Also, according to the present embodiments, the amount of metal needed to manufacture the barrier rib structure is less than the amount of metal needed in the prior art. For example, in a conventional etching process, a large amount of metal is applied and is then removed. However, in the present embodiments, no metal is removed, thereby minimizing manufacturing costs.  
      While the present embodiments have been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present embodiments as defined by the following claims.