Abstract:
Disclosed are green sheets that can be used to shorten the fabrication procedure of plasma display panels and to improve the configuration and crystalline state of electrodes. The green sheets for use in the fabrication of display panels comprise a dielectric layer green sheet to which a plurality of electrode materials are bound at regular intervals, and at least one protective film attached to at least one surface of the dielectric layer green sheet. Further disclosed are a method and an apparatus for producing the green sheets, plasma display panels using the green sheets, and methods fabricating the plasma display panels.

Description:
[0001]     This application claims the benefit of Korean Patent Application No. 10-2005-0112014, filed on Nov. 22, 2005, Korean Patent Application No. 10-2006-0000516, filed on Jan. 3, 2006, and Korean Patent Application No. 10-2006-0001488, filed on January 5, which are hereby incorporated by references as if fully set forth herein.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to green sheets, a method and an apparatus for producing the green sheets, plasma display panels using the green sheets, and methods for fabricating the plasma display panels. More particularly, the present invention relates to green sheets that can be used to shorten the fabrication procedure of plasma display panels and to improve the configuration and crystalline state of electrodes, a method and an apparatus for producing the green sheets, plasma display panels using the green sheets, and methods fabricating the plasma display panels.  
         [0004]     2. Discussion of the Related Art  
         [0005]     Plasma display panels (PDPs) are emissive devices that display images using a discharge phenomenon. Since there is no necessity to mount active components on respective cells of PDPs, the fabrication procedure of PDPs is simplified. Other advantages of PDPs are ease of scale-up of screens and high response speed. Based on these advantages, PDPs are currently in the spotlight as display devices of large-screen image displays.  
         [0006]     The structure of a general plasma display panel is shown in  FIG. 1 . As shown in  FIG. 1 , the plasma display panel comprises an upper panel  10  and a lower panel  20  facing and stacked on the upper panel. The upper panel  10  includes an upper substrate  11  and a plurality of sustain electrode pairs, each of which consists of a transparent electrode  12  and a bus electrode  13 .  
         [0007]     The sustain electrodes are covered with a dielectric layer  14 , and a protective film  15  is formed on the dielectric layer  14 .  
         [0008]     The lower panel  20  includes a lower substrate  21 , a plurality of address electrodes  22  arranged on the lower substrate, a dielectric layer  23  formed on the address electrodes  22 , and stripe or well type barrier ribs  24  formed on the dielectric layer  23  to separate respective discharge cells (i.e. discharge spaces) wherein red, blue and green phosphor layers  26  for color display are formed within the cells separated by the barrier ribs  24  to create sub-pixels.  
         [0009]     The discharge cells  25  are separated as sub-pixels by the barrier ribs  24 . A discharge gas is included in the discharge cells  25 . One pixel consists of three sub-pixels.  
         [0010]     The bus electrodes  13 , particularly those containing silver (Ag), are commonly formed by a process using an electrode paste or a dry film process using a green sheet.  
         [0011]     According to the former process, a black matrix (BM) paste is applied over the entire surface of the upper substrate  11 , on which the transparent electrode patterns  12  are formed, by printing, and dried.  
         [0012]     After the dried structure is exposed to light using a mask for black matrix layers, the exposed portions of the black matrix are etched using a developing solution to form black matrix patterns.  
         [0013]     The black matrix patterns are generally formed in non-discharge zones between pairs of transparent electrodes  12 . At this time, black layers may also be formed between the pairs of transparent electrodes  12  to increase the contrast of the PDP.  
         [0014]     An electrode paste for bus electrodes is printed on the substrate, on which the black matrix patterns are formed, in the same manner as in the formation of the black matrix layers, and dried.  
         [0015]     After the dried structure is exposed to light using a mask for electrodes, etching is performed using a developing solution to form patterns. Thereafter, the patterns are calcined to form the bus electrodes  13 .  
         [0016]     However, the process using a paste and the dry film process for forming electrodes are space and time consuming because they require the use of additional equipment, such as printers and masks for printing, for the printing and drying steps, and involve an additional drying step.  
         [0017]     Silver (Ag) present in the paste used to form the electrodes is in the form of particles, and a vehicle (e.g., an organic binder) is used together with the silver particles to form the patterns. The patterns are sintered to have a crystalline state.  
         [0018]     That is, when silver (Ag) particles  27  present in a paste or a green sheet are subjected to calcination, they are sintered to form crystalline electrodes  28 . The formation of the crystalline electrodes  28  is illustrated in  FIGS. 2 and 3 .  
         [0019]     The characteristics of silver (Ag) contained the crystalline silver (Ag) electrodes  28  are poor as compared to those of the bulky silver (Ag) raw material. That is, the crystalline state of the silver (Ag) electrodes  28  affects the resistance and other electrical properties of the electrodes  28 .  
         [0020]     As indicated by the dotted lines shown in  FIG. 3 , many interfaces  29  are present in the silver (Ag) crystals prepared by calcining silver (Ag) particles. The presence of the interfaces  29  causes a deterioration in the characteristics of silver (Ag) contained in the crystalline silver (Ag) electrodes  28 , compared to those of the bulky raw material. Particularly, the electrical resistance of the electrodes  28  is greatly increased at the interfaces  29 .  
         [0021]     Moreover, the conventional processes for forming silver (Ag) electrodes become obstacles in forming electrodes of panels with high definition.  
         [0022]     Increases in the size and degree of crystallization of silver (Ag) particles are considered as improvements in the formation of silver (Ag) electrodes.  
         [0023]     In addition, bus electrodes and a dielectric layer are formed by different processes, making the overall procedure complicated. Furthermore, since light exposure and development steps are carried out to form bus electrodes, a loss in materials of the photosensitive electrode paste applied to areas other than the bus electrodes may be caused.  
         [0024]     On the other hand, the structures of black matrix layers formed in an active area where images are actually displayed are different from those of black matrix layers formed in a pad area other than the active area, resulting in damage to the structure of electrodes formed on the respective black matrix layers.  
         [0025]     As apparent from  FIG. 4  and  FIGS. 5A, 5B  and  5 C, which are cross-sectional views of the regions ‘a’, ‘b’ and ‘c’ shown in  FIG. 4 , respectively, a black matrix layer  16  is formed on portions of the surfaces of two transparent electrodes  12  formed on an upper substrate  11  and on a portion of the surface of the upper substrate  11  exposed between the transparent electrodes in an active area (the region ‘a’), whereas black matrix layers  16  are formed only on portions of the surface of an upper substrate  11  where bus electrodes  13  are to be formed in a pad area (the region ‘b’), or a black matrix layer  16  is formed only on a portion of the surface of an upper substrate  11  where a bus electrodes  13  is to be formed in a pad area (the region ‘c’).  
         [0026]     As demonstrated from the fabrication procedure of a PDP, since a paste for black matrix layers and a paste for bus electrodes are screen-printed and dried to form the black matrix layers  16  and the bus electrodes  13 , the use of equipment for the screen printing is required and the drying step is additionally involved.  
         [0027]     When a paste for black matrix layers is exposed to light using a mask for black matrix layers, only the active area (the region ‘a’) is exposed and the pad area (the regions ‘b’ and ‘c’) are not exposed. As a result, since the black matrix layers  16  are not cured before calcining, there is a high probability that the patterns formed in the pad area will collapse upon development and calcination of the patterns. This collapse of the patterns may damage the structure of the electrodes formed on the black matrix layers.  
       SUMMARY OF THE INVENTION  
       [0028]     Accordingly, the present invention is directed to green sheets, a method and an apparatus for producing the green sheets, plasma display panels using the green sheets and methods fabricating the plasma display panels that substantially obviate one or more problems due to limitations and disadvantages of the related art.  
         [0029]     An object of the present invention is to provide plasma display panels and method for fabricating the plasma display panels by which the fabrication procedure is simplified, loss of materials for electrodes can be prevented, and electrode patterns can be formed without involving any drying step.  
         [0030]     Another object of the present invention is to provide green sheets that solve problems arising from alignment between black matrix layers and electrodes in a pad area, avoid the collapse of patterns upon development and calcination of the patterns to make the patterns fine, and improve the configuration and crystalline state of the electrodes to lower the electrical resistance of the electrodes, resulting in an improvement in the overall efficiency of panels; a method and an apparatus for producing the green sheets; plasma display panels using the green sheets; and methods fabricating the plasma display panels.  
         [0031]     Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.  
         [0032]     To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a green sheet for use in the fabrication of a display panel comprises a dielectric layer green sheet to which a plurality of electrode materials are bound at regular intervals; and at least one protective film attached to at least one surface of the dielectric layer green sheet.  
         [0033]     In another aspect of the present invention, there is provided a green sheet comprising an electrode green sheet; a photosensitive organic material layer disposed on one surface of the electrode green sheet; and a protective film for protecting the electrode green sheet and/or a protective film for protecting the photosensitive organic material layer.  
         [0034]     In another aspect of the present invention, there is provided a method for fabricating a plasma display panel, the method comprising applying a photosensitive black matrix green sheet to an upper substrate and exposing the photosensitive black matrix green sheet to light using a mask for black matrix layers; applying an electrode green sheet to the black matrix green sheet and exposing the electrode green sheet to light using a mask for electrodes; and developing the exposed black matrix green sheet and the exposed electrode green sheet.  
         [0035]     In another aspect of the present invention, there is provided a method for producing a green sheet, the method comprising attaching a dielectric layer green sheet to one surface of a first protective film and burying electrode materials at regular intervals in the dielectric layer green sheet to bind the electrode materials to the dielectric layer green sheet.  
         [0036]     In another aspect of the present invention, there is provided an apparatus for producing a green sheet, the apparatus comprising a pair of first rollers for attaching a dielectric layer green sheet to one surface of a first protective film, an electrode material feeder for forming electrode materials having predetermined patterns on a second protective film, and a pair of second rollers for binding the electrode materials having predetermined patterns formed by the electrode material feeder to the dielectric layer green sheet.  
         [0037]     In another aspect of the present invention, there is provided a plasma display panel comprising electrodes formed by forming a silver (Ag) raw material into a thin film.  
         [0038]     In another aspect of the present invention, there is provided a plasma display panel comprising an upper panel and a lower panel, each of which including electrodes, wherein at least one electrode of the electrodes is an electrode having a crystal structure of a silver (Ag) raw material.  
         [0039]     In another aspect of the present invention, there is provided a method for fabricating a plasma display panel, the method comprising forming a silver (Ag) raw material into a thin-film silver (Ag) layer and transferring the silver (Ag) layer to the surface of an upper or lower substrate, and patterning the silver (Ag) layer to form electrodes.  
         [0040]     In yet another aspect of the present invention, there is provided an upper panel of a plasma display panel, the upper panel comprising a substrate; transparent electrodes formed on one surface of the substrate; bus electrodes formed on the respective transparent electrodes, the bus electrodes being formed using a thin film of a silver (Ag) raw material; a dielectric layer covering the transparent electrodes, the bus electrodes and the substrate; and a protective film disposed on the dielectric layer.  
         [0041]     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0042]     The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings:  
         [0043]      FIG. 1  is a perspective view of a general plasma display panel;  
         [0044]      FIG. 2  is an enlarged view showing a state wherein electrode materials of a conventional plasma display panel are applied;  
         [0045]      FIG. 3  is an enlarged view showing a state wherein the electrode materials shown in  FIG. 2  are calcined;  
         [0046]      FIG. 4  is a top view of an upper panel of a conventional plasma display panel;  
         [0047]      FIGS. 5A, 5B  and  5 C are cross-sectional views of the regions ‘a’, ‘b’ and ‘c’ shown in  FIG. 4 , respectively;  
         [0048]      FIG. 6  is a top view of an upper panel of a plasma display panel according to one embodiment of the present invention;  
         [0049]      FIGS. 7A, 7B  and  7 C are cross-sectional views of the regions ‘a’, ‘b’ and ‘c’ shown in  FIG. 6 , respectively;  
         [0050]      FIG. 8A  is a cross-sectional view of a green sheet according to one embodiment of the present invention, and  FIG. 8B  is a cross-sectional view of a green sheet according to another embodiment of the present invention;  
         [0051]      FIGS. 9A through 9E  are cross-sectional views illustrating a method for fabricating a plasma display panel according to one embodiment of the present invention;  
         [0052]      FIG. 10  is a schematic view illustrating a method for producing a green sheet according to an embodiment of the present invention;  
         [0053]      FIG. 11  is a top view illustrating the formation of patterns of bus electrodes using a green sheet of the present invention;  
         [0054]      FIG. 12  is a cross-sectional view illustrating the fabrication of a PDP using a green sheet of the present invention;  
         [0055]      FIG. 13  is a schematic view illustrating the production of an electrode material of a plasma display panel according to an embodiment of the present invention;  
         [0056]      FIGS. 14 through 16  are cross-sectional views illustrating the steps of a method for fabricating a plasma display panel according to another embodiment of the present invention; and  
         [0057]      FIG. 17  is a cross-sectional view of a plasma display panel according to another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0058]     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.  
       First Embodiment  
       [0059]      FIG. 6  is a top view of an upper panel of a PDP according to the present invention, and shows that the structures of black matrix layers  30  formed in an active area where images are actually displayed are different from those of black matrix layers  30  formed in a pad area other than the active area.  
         [0060]      FIGS. 7A, 7B  and  7 C are cross-sectional views of the regions ‘a’, ‘b’ and ‘c’ shown in  FIG. 6 , respectively. As is evident from  FIGS. 7A, 7B  and  7 C, a black matrix layer  30  is formed on portions of the surfaces of transparent electrodes  60  formed on an upper substrate  50  and on a portion of the surface of the upper substrate  50  exposed between the transparent electrodes  60  in an active area (the region ‘a’), whereas a black matrix layer  30  is formed on a portion of the surface of an upper substrate  50  where bus electrodes  40  are to be formed as well as on other portions of the surface of the upper substrate  50  in a pad area (the region ‘b’ or ‘c’).  
         [0061]     That is, a black matrix layer  30  is formed on portions of the surfaces of two transparent electrodes  60  formed on an upper substrate  50  and on a portion of the surface of the upper substrate  50  exposed between the transparent electrodes  60 , as shown in the cross-sectional view of a cell (the region ‘a’) formed in the active area. Meanwhile, a black matrix layer  30  is formed over the entire surface of an upper substrate  50 , as shown in the cross-sectional views of the pad area (the region ‘b’ or ‘c’).  
         [0062]     The black matrix layers  30  and the bus electrodes  40  shown in  FIG. 6  are formed using respective green sheets.  FIGS. 8A and 8B  show cross-sectional views of a black matrix green sheet  31  and a bus electrode green sheet  41 , respectively.  
         [0063]     As shown in  FIG. 8A , protective films  32  and  33  are attached to upper and lower surfaces of the black matrix green sheet  31 , respectively, to protect the black matrix green sheet  31 .  
         [0064]     The black matrix green sheet  31  is composed of a negative photosensitive organic material and a powder for black matrix layers having a non-conductive blackness. When the black matrix green sheet  31  is exposed to light, the exposed portions only are cured and remain after development.  
         [0065]     As shown in  FIG. 8B , a photosensitive organic material layer  42  is formed on the bus electrode green sheet  41 , and protective films  43  and  44  are attached to protect the photosensitive organic material layer  42  and the bus electrode green sheet  41 , respectively.  
         [0066]     The photosensitive organic material layer  42  is formed of a negative photoresist (PR) photosensitive organic material. When the photosensitive organic material layer  42  is exposed to light using a mask for bus electrodes, the exposed portions of the photosensitive organic material layer  21  only remain. The bus electrode green sheet  41  is composed of a silver (Ag) powder and an organic material capable of being dissolved in a developing solution irrespective of light exposure.  
         [0067]      FIGS. 9A through 9E  illustrate a method for fabricating a PDP using the black matrix green sheet  31  and the bus electrode green sheet  41  shown in  FIGS. 8A and 8B , respectively.  
         [0068]     As shown in  FIG. 9A , a material (e.g., ITO) is applied to an upper substrate  50   a  and is then patterned using a patterned mask (not shown) for transparent electrodes to form transparent electrodes  60 .  
         [0069]     Next, as shown in  FIG. 9B , a black matrix green sheet  31  is laminated using a laminator on the upper substrate  50  having the transparent electrodes  60  formed thereon, and then a mask  34  for black matrix layers is disposed over the black matrix green sheet  31 . UV irradiation is performed to cure portions of the negative photosensitive organic material contained in the black matrix green sheet  31  where black matrix layers are to be formed.  
         [0070]     Then, as shown in  FIG. 9C , the bus electrode green sheet  41  and the photosensitive organic material layer  42  are sequentially laminated using a laminator on the exposed black matrix green sheet  31 , and a mask  45  for bus electrodes is disposed at a certain distance apart from the photosensitive organic material layer  42 . Thereafter, UV irradiation is performed. At this time, only the pattern exposed portions of the photosensitive organic material layer  42 , which is formed of a negative PR, formed on the bus electrode green sheet  41  are cured.  
         [0071]     Next, as shown in  FIG. 9D , the resulting structure is developed with a developing solution, leaving only the cured portions of the photosensitive organic material layer  42  and the black matrix green sheet  31 . The uncured portions of the photosensitive organic material layer  42  and the black matrix green sheet  31  are developed by the developing solution. That is, portions of the black matrix green sheet  31  remain on portions of the surfaces of the transparent electrodes  60  and on portions of the surface of the upper substrate  50  exposed between the transparent electrodes  60 . The cured portions of the photosensitive organic material layer  42  and the bus electrode green sheet  41  remain only on the portions of the black matrix green sheet  31  formed on the transparent electrodes  60 .  
         [0072]     The portions of the bus electrode green sheet  41  exposed by patterning the photosensitive organic material layer  42  are dissolved and removed by the developing solution.  
         [0073]     Next, as shown in  FIG. 9E , the resulting structure is calcined to form black matrix layers  30  and bus electrodes  40 . Since the photosensitive organic material layer  42  formed on the bus electrodes  40  is formed of an organic material only, it is completely burned and removed upon calcining.  
         [0074]     Following the above procedure, an upper plate structure of the active area where images are actually displayed in a PDP is formed. The formation procedure of black matrix layers in an upper plate structure formed in the pad area is different from that of the black matrix layers in the upper plate structure formed in the active area. It should be noted that transparent electrodes are not formed in the pad area.  
         [0075]     That is, when the black matrix green sheet is laminated and irradiated with UV light, the entire portion of the black matrix green sheet laminated in the pad area is exposed and cured without being patterned. As a result, a black matrix layer is formed over the entire surface of the upper substrate  60  in the pad area without being developed.  
         [0076]     According to the method of the present invention, since a black matrix layer is formed over the entire surface of an upper substrate in the pad area rather than being formed only in the regions of bus electrodes, the collapse of the patterns, which may occur because the black matrix layer is not exposed, can be prevented. Therefore, the method of the present invention solves problems arising from alignment and enables the formation of fine patterns.  
       Second Embodiment  
       [0077]     With reference to  FIG. 10 , an apparatus for producing the green sheets according to the present invention will be explained below.  
         [0078]     First, a dielectric layer green sheet  71  is attached to a first protective film  72  by means of a pair of first rollers  73  and  74 , and electrode materials  46  are formed on a second protective film  47  by means of an electrode material feeder  80 .  
         [0079]     The dielectric layer green sheet  71 , to which the first protective film  72  is attached, is attached to the second protective film  47 , on which the electrode materials  46  are formed, by means of a pair of second rollers  75  and  76 .  
         [0080]     The apparatus of the present invention serves to apply the dielectric layer green sheet  71  to the first protective film  72  and to bind the electrode materials  46  thereto.  
         [0081]     Specifically, the dielectric layer green sheet  71  and the first protective film  72  are passed through the pair of first rollers  73  and  74  to produce a dielectric member, and then the dielectric member and the second protective film  47 , on which the electrode materials  46  are formed, are passed through the pair of second rollers  75  and  76  to bind the electrode materials  46  to the dielectric layer green sheet  71 .  
         [0082]     As shown in  FIG. 10 , the electrode materials  46  may be arranged at regular intervals on the protective film  47 . The electrode materials  46  may be used as bus electrodes of a plasma display panel.  
         [0083]     The electrode materials  46  are bound to the dielectric layer green sheet  71  such that they are buried in the dielectric layer green sheet  71 . The electrode materials  46  buried in the dielectric layer green sheet  71  can be used to fabricate a plasma display panel.  
         [0084]     The electrode materials  46  may be formed on the second protective film  47  by an inkjet printing, dispensing or offset printing technique. Instead of the dielectric layer green sheet  71 , a dielectric paste may be used as a dielectric material by screen printing.  
         [0085]     The green sheet is produced using the apparatus in accordance with the following procedure. First, a composition for a dielectric layer green sheet is applied to a carrier film and dried to form the dielectric layer green sheet  71  in the form of a film.  
         [0086]     Then, the dielectric layer green sheet  71  and the first protective film  72  are passed through a pair of first rollers  73  and  74  such that they are attached to each other.  
         [0087]     The first protective film  72  may be formed of polyethylene terephthalate, polyethylene naphthalate or polyethylene. A release agent, such as a silicone resin, may be applied to one surface of the plastic film.  
         [0088]     The dielectric layer green sheet  71  is attached to the first protective film  72  to produce a green sheet member, and at the same time, the electrode materials  46  are attached to the second protective film  47 .  
         [0089]     As mentioned above, the electrode materials  46  may be formed on the second protective film  47  by an inkjet printing, dispensing or offset printing technique.  
         [0090]     For example, according to the offset printing technique, a silver (Ag) composition of bus electrodes is injected into a negative plate, adhered to a cylinder of a blanket, and printed between protective films.  
         [0091]     The silver (Ag) composition is printed on the protective film  47  to form bus electrodes. Meanwhile, according to the inkjet printing or dispensing technique, an ink containing a silver (Ag) composition for bus electrodes is sprayed on a protective film to form electrode materials.  
         [0092]     Then, the dielectric member and the second protective film on which the electrode materials  46  are formed are passed through the pair of second rollers  75  and  76  such that they are attached to each other.  
         [0093]     This attachment is performed in such a manner that the electrode materials  46  are buried in the dielectric member. The surface of the electrode materials  46  attached to the second protective film  47  and the surface of the dielectric layer green sheet  71  may be planarized.  
         [0094]     That is, in the case where the electrode materials  46  whose one surface is exposed and the dielectric layer green sheet  71  in which the electrode materials are buried are applied to a certain structure in subsequent processing, the electrical connectivity of the electrode materials  46  and the protection effects of the dielectric layer green sheet  71  can be ensured.  
         [0095]     An adhesive layer may be further formed to enhance the adhesion of the electrode materials  46  to the dielectric layer green sheet  71 . The adhesive layer may be formed by one-time screen printing of a dielectric paste having adhesive properties on the dielectric member.  
         [0096]     Since the electrode materials  46  are formed at regular intervals, air bubbles may occur due to the presence of pores when the dielectric layer green sheet  71  is attached to the second protective film  47  on which the electrode materials are formed. The air bubbles may damage electrodes formed from the electrode materials  46 . Accordingly, the occurrence of air bubbles must be inhibited as much as possible.  
         [0097]     As shown in  FIG. 11 , patterns of the electrode materials  46  formed along the moving direction (A) of the dielectric layer green sheet  71  are combined with the flowability of the adhesive layer, and the compressive force of the second rollers  75  and  76  is applied thereto to inhibit the occurrence of air bubbles.  
         [0098]     As shown again in  FIG. 11 , the electrode materials  46  formed on the dielectric layer green sheet  71  or the electrode patterns of the electrode materials  46  formed at both ends have a greater width than those formed in the middle portion.  
         [0099]     Since the electrodes formed at both ends are connected to respective external connection lines, their width is relatively large. Meanwhile, since the electrodes formed in the middle portion serve to define the columns and rows of pixel cells, they have widths corresponding to the pitch intervals of the pixel cells. At this time, the patterns of the electrode materials  46  are formed along the moving direction (A) of the dielectric layer green sheet  71  to minimize the occurrence of air bubbles due to the presence of pores in the dielectric layer green sheet  71  and the electrode materials  46 .  
         [0100]     Further, the dielectric paste of the adhesive layer is subjected to embossing by the compressive force of the second rollers  75  and  76  so that it is aligned between the electrode materials  46 . At this time, the second rollers  75  and  76  may be heated to enhance the adhesion of the adhesive layer to the electrode materials  46 .  
         [0101]     As shown in  FIG. 12 , the dielectric layer green sheet  71  containing the electrode materials  46  is laminated on the substrate  50  to simultaneously form electrodes  40  and a dielectric layer  70 , followed by calcination to produce an upper or lower plate of a PDP.  
         [0102]     In conclusion, only two steps, i.e. lamination using the green sheet and calcination, are carried to produce an upper or lower plate of a PDP. Therefore, the overall procedure is simplified and electrodes, e.g., bus electrodes, can be formed without any loss in materials.  
       Third Embodiment  
       [0103]     As shown in  FIG. 13 , a bulky silver (Ag) raw material  48  is used to form an electrode material  49  in the form of a thin film, which may be used to form electrodes of a plasma display panel.  
         [0104]     The electrode material  49  may be in the form of a silver (Ag) thin film or foil.  
         [0105]     As shown in  FIG. 13 , the bulky silver (Ag) raw material  48  is formed into a foil by means of a pair of rollers  77 , and the foil is further rolled by means of a pair of rollers  78  to produce the final electrode material  49  having a thickness suitable for use in a PDP.  
         [0106]     It is to be appreciated that the silver (Ag) raw material  48  may be rolled only one time by means of the pair of rollers  77  to produce the final electrode material  49  having a suitable thickness.  
         [0107]     The electrode material  49  having a suitable thickness is softened to control the hardness and ductility of the electrode material.  
         [0108]     The electrode material  49  may be laminated on a dry film resist, such as a green sheet, to facilitate the transfer and patterning of electrodes.  
         [0109]     Since the electrode material is produced through rolling and softening, the crystal structure of the raw material may remain unchanged.  
         [0110]     According to a conventional process using silver (Ag) particles, a silver (Ag) raw material is divided into particles and becomes polycrystals whose crystal structures are isolated. In contrast, according to the present invention, the distance between the crystals of the electrode material  49  can be shortened during rolling and softening, but the structure of the crystals can be maintained despite increased density of the crystals.  
         [0111]     Since electrodes of a PDP formed using the thin-film electrode material  49  have a relatively small number of interfaces than conventional electrodes formed using an electrode paste or a green sheet containing silver (Ag) particles, the electrical resistance of the electrodes formed using the thin-film electrode material  49  is not decreased.  
         [0112]     Due to excellent electrical properties of the electrode material  49 , electrodes can be formed using the electrode material  49  to have a smaller thickness than conventional electrodes.  
         [0113]     Conventional electrodes formed using silver (Ag) particles have a thickness of 4 to 5 μm after calcining, whereas electrodes formed using the electrode material  49  preferably have a thickness of 5 to 10 μm.  
         [0114]     The electrode material  49  may be used to form bus electrodes in an upper panel or address electrodes in a lower panel of a PDP.  
         [0115]     Bus electrodes of a PDP are formed using the electrode material  49  in accordance with the following procedure.  
         [0116]     First, transparent electrodes  60  are formed on a substrate  50 . Black matrix layers  31  are formed on the respective transparent electrodes  60 .  
         [0117]     Then, as shown in  FIG. 14 , the electrode material  49  is transferred to the surfaces of the black matrix layers  31 .  
         [0118]     On the other hand, the black matrix layers  31  formed on the transparent electrodes  60  may be extended to non-discharge zones between the pair of the transparent electrodes  60  to increase the contrast of a panel. In this case, the black matrix layers (black layers) formed in non-discharge zones have insulating properties.  
         [0119]     Then, as shown in  FIG. 15 , etching is performed using a mask  36  having openings  35  to pattern the electrode material  49  into electrode patterns. As a result, electrodes  40  are formed ( FIG. 16 ).  
         [0120]     It is desirable that the electrode material  49  be etched using an acid because it is formed of silver (Ag).  
         [0121]     The black matrix layers  31  are viscous, causing no difficulty in transferring the electrode material  49  to the surfaces of the black matrix layers  31 .  
         [0122]     In the case where the electrode material  49  is directly transferred to the surfaces of the transparent electrodes  60  in the absence of the black matrix layers  31 , an adhesive may be used.  
         [0123]     As shown in  FIG. 17 , a dielectric layer  70  is formed to cover the electrodes  60  and  40 , and a protective film  90  is formed to cover the dielectric layer  70  to complete the production of an upper panel.  
         [0124]     On the other hand, the electrode material  49  may be used to form address electrodes on a lower substrate. In this case, the address electrodes are formed by forming an under layer on the lower substrate, transferring the electrode material  49  to the surface of the under layer, and patterning the electrode material.  
         [0125]     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.