Abstract:
A liquid crystal display (LCD) device using the COA process. The LCD device includes a passivation layer formed on metal wires in the wire-collecting area for preventing metal wires from exposure. Or, the LCD device includes an insulation layer formed between outer leads in the outer lead bonding (OLB) area for improving insulation among the outer leads.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The invention relates to a liquid crystal display (LCD) device, more particularly to a liquid crystal display (LCD) device using the COA process.  
         [0003]     2. Description of the Prior Art  
         [0004]     The conventional TFT-LCD panel was assembled by a TFT glass substrate, a color filter glass substrate, and the liquid crystal injected into the gap between such two substrates. In the past, the alignment between the TFT glass substrate and the color filter glass substrate must be made accurately. Therefore, the yield of the cell process is the lowest one in comparison to the whole panel process. If we can prevent from the loss under such process, the whole yield and the cost reduction can be improved greatly. For the new mass production technology, which is the so-called COA (color filter on array) technology, the color filter process should be executed after the TFT array process for the TFT glass substrate. By means of the COA technology, higher aperture ratio of the TFT glass substrate is obtained, thus improving the brightness of the panel effectively.  
         [0005]     Please refer to  FIG. 1  and  FIG. 2 .  FIG. 1  is the cross-sectional view for the conventional TFT-LCD device. The TFT glass substrate  11  and the color filter glass substrate  12  are adhered each other. There are a plurality of TFTs  111  on the TFT glass substrate  11 . Each TFT  111  is corresponding to one pixel electrode  112 . The transparent dielectric layer  113  is put between the TFTs  111  and the pixel electrodes  112 . There are a plurality of color filters  121  in the red (R), green (G), and blue (B) color on the color filter glass substrate  12 . The black matrix (BM)  122  separates every two color filters in order to prevent from light leakage. A transparent common electrode  123  is disposed on the color filters  121 . A liquid crystal layer  13  is injected into the gap between the TFT glass substrate  11  and the color filter glass substrate  12 .  
         [0006]      FIG. 2  is the cross-sectional view for the TFT-LCD device using the COA technology. The bottom glass substrate  21  and the top glass substrate  22  are adhered each other. There are a plurality of TFTs  211  on the bottom glass substrate  21 . Each TFT  211  is corresponding to one pixel electrode  212 . There are a plurality of color filters  213  in the red (R), green (G), and blue (B) color between the TFTs  211  and the pixel electrodes  212 . The black matrix (BM)  214  separates every two color filters in order to prevent from light leakage. A transparent common electrode  221  is disposed on the top glass substrate  22 . A liquid crystal layer  23  is injected into the gap between the bottom glass substrate  21  and the top glass substrate  22 .  
         [0007]      FIG. 3  illustrates the structure of the TFT device using the COA technology. The black matrix (BM) area  32  is around the active area  31 , the wire-collecting area  33  is adjacent to the BM area  32 , and the outer lead bonding (OLB) area  34  is adjacent to the wire-collecting area  33 . The active area  31 , the wire-collecting area  33  and the OLB area  34  are connected electrically. Metal wires in the active area  31  are protected by a passivation layer. However, there is no passivation layer to protect metal wires in the wire-collecting area  33  and the OLB area  34 . Therefore, metal wires in the wire-collecting area  33  and the OLB area  34  are exposed and easily invaded by moisture. It may result in poor product reliability.  
       SUMMARY OF THE INVENTION  
       [0008]     In the light of the state of the art described above, it is an object of the present invention to provide a liquid crystal display (LCD) device using the COA process which is immune to the problems of the structure of the conventional LCD device described above.  
         [0009]     It is another object of this invention to provide a liquid crystal display (LCD) device using the COA process for preventing the wire-collecting area from exposure in order to improve the product reliability. The metal wires in the wire-collecting area is covered by a BM layer or a CF layer.  
         [0010]     It is a further object of this invention to provide a liquid crystal display (LCD) device using the COA process to improve the insulation among the outer leads. A BM layer or a CF layer, serving as an insulation layer, is formed between the outer leads in the outer lead bonding (OLB) area.  
         [0011]     In view of the above and other objects which will become apparent as the description proceeds, there is provided according to a general aspect of the present invention a liquid crystal display (LCD) device using the color filter on array (COA) process which comprises an active area; a black matrix (BM) area surrounding said active area, in which a black matrix layer is formed; a wire-collecting area with a plurality of metal wires being adjacent to said BM area and connecting electrically with said active area; an outer lead bonding (OLB) area with a plurality of outer leads being adjacent to and connecting electrically with said wire-collecting area; and a passivation layer formed on the metal wires in said wire-collecting area for preventing said plurality of metal wires from exposure.  
         [0012]     Based on the idea described above, said passivation layer can be the black matrix layer formed in both the BM area and the wire-collecting area, or a color filter layer.  
         [0013]     The LCD device can further include an insulation layer formed between the outer leads in the OLB area.  
         [0014]     Based on the idea described above, the insulation layer can be the black matrix layer formed both in the BM area and between the outer leads in the OLB area.  
         [0015]     Based on the aforementioned idea, said insulation layer can be an organic resin material.  
         [0016]     Based on the idea described above, said insulation layer can be a color filter layer.  
         [0017]     Based on the aforementioned idea, the height of said insulation layer can be lower than the height of said outer leads.  
         [0018]     Based on the idea described above, the height of said insulation layer can be from about 0.5 micron to about 3 micron.  
         [0019]     In view of the above and other objects which will become apparent as the description proceeds, there is provided according to a general aspect of the present invention a liquid crystal display (LCD) device using the color filter on array (COA) process which comprises an active area; a black matrix (BM) area surrounding said active area, in which a black matrix layer is formed; a wire-collecting area with a plurality of metal wires being adjacent to said BM area and connecting electrically with said active area; an outer lead bonding (OLB) area with a plurality of outer leads being adjacent to and connecting electrically with said wire-collecting area; and an insulation layer formed between the outer leads.  
         [0020]     Based on the idea described above, the insulation layer can be the black matrix layer formed both in the BM area and between the outer leads in the OLB area.  
         [0021]     Based on the aforementioned idea, said insulation layer can be an organic resin material.  
         [0022]     Based on the idea described above, said insulation layer can be a color filter layer.  
         [0023]     Based on the aforementioned idea, the insulation layer can be a red, green, blue color filter, or a combination thereof.  
         [0024]     Based on the idea described above, the height of said insulation layer can be lower than the height of said outer leads.  
         [0025]     Based on the aforementioned idea, the height of said insulation layer can be from about 0.5 micron to about 3 micron.  
         [0026]     Based on the idea described above, the material of said metal wires can be selected from the group consisting of Mo, Al and both.  
         [0027]     The LCD device can further include a protective film covering the metal wires.  
         [0028]     Based on the idea described above, the protective film can be selected from the group consisting of ITO, IZO and both. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0029]     The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0030]      FIG. 1  schematically illustrates the cross-sectional view of a conventional TFT-LCD device;  
         [0031]      FIG. 2  schematically illustrates the cross-sectional view of a conventional TFT-LCD device using the COA technology;  
         [0032]      FIG. 3  schematically illustrates a front view of a conventional TFT-LCD device using the COA technology;  
         [0033]      FIG. 4A  schematically illustrates a front view of the TFT-LCD device according to the first embodiment of the present invention;  
         [0034]      FIG. 4B  is the cross-sectional view of  FIG. 4A  in the XX′ direction according to the first embodiment of the present invention;  
         [0035]      FIG. 5A  schematically illustrates a front view of the TFT-LCD device according to the second embodiment of the present invention;  
         [0036]      FIG. 5B  is the cross-sectional view of  FIG. 5A  in the XX′ direction according to the second embodiment of the present invention;  
         [0037]      FIG. 6A  schematically illustrates a front view of the TFT-LCD device according to the third embodiment of the present invention;  
         [0038]      FIG. 6B  is the cross-sectional view of  FIG. 6A  in the YY′ direction according to the third embodiment of the present invention;  
         [0039]      FIG. 6C  is the cross-sectional view of  FIG. 6A  in the YY′ direction according to the fourth embodiment of the present invention;  
         [0040]      FIG. 7A  schematically illustrates a front view of the TFT-LCD device according to the fifth embodiment of the present invention;  
         [0041]      FIG. 7B  shows the cross-sectional views of  FIG. 7A  in the XX′ and YY′ directions according to the fifth embodiment of the present invention;  
         [0042]      FIG. 8A  schematically illustrates a front view of the TFT-LCD device according to the sixth embodiment of the present invention; and  
         [0043]      FIG. 8B  shows the cross-sectional views of  FIG. 8A  in the XX′ and YY′ directions according to the sixth embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0044]     Some sample embodiments of the present invention will now be described in greater detail. Nevertheless, it should be recognized that the present invention can be practiced in a wide range of other embodiments besides those explicitly described, and the scope of the present invention is expressly not limited except as specified in the accompanying claims.  
         [0045]     Please refer to  FIG. 4A  and  FIG. 4B , a front view of the TFT-LCD device and a cross-sectional view of the wire-collecting area according to the first embodiment of the present invention are shown.  FIG. 4B  is the cross-sectional view of  FIG. 4A  in the XX′ direction. First, a series of the procedures forming TFTs, a wire-collecting area  411 , and an outer lead bonding (OLB) area  412  are executed on a transparent glass substrate  42 . After such procedures, a plurality of protruding metal wires  43  will be formed in the wire-collecting area  411  as illustrated in  FIG. 4B . The active area  41 , the wire-collecting area  411  and the OLB area  412  are electrically connected. The material of the metal wires  43  is usually molybdenum (Mo), aluminum (Al) or the stack of Mo and Al. In general, a protective film  44 , such as indium tin oxide (ITO) or indium-doped zinc oxide (IZO), is sputtered on the surface of the metal wires  43  in order to prevent from oxidation of the metal wires  43 .  
         [0046]     After the above steps, the black matrix [BM] layer process will be executed. First, an organic resin material is formed on the substrate  42  by the spin-coating method. Then, the organic resin material located on the active area  41  and the OLB area  412  is removed by exposure, development and baking, thus forming a black matrix (BM) layer  45  in a black matrix area  413  and in the wire-collecting area  411 , as shown in  FIGS. 4A and 4B . The black matrix area  413  surrounds the active area  41 . Thus, the wire-collecting area  411  is covered by the BM layer  45  as a passivation layer. In this way, exposure of the metal wires  43  in the wire-collecting area  411  is prevented, thus improving product reliability.  
         [0047]     Please refer to  FIG. 5A  and  FIG. 5B , a front view of the TFT-LCD device and a cross-sectional view of the wire-collecting area according to the second embodiment of the present invention are shown.  FIG. 5B  is the cross-sectional view of  FIG. 5A  in the XX′ direction. First, a series of the procedures forming TFTs, a wire-collecting area  411 , and an outer lead bonding (OLB) area  412  are executed on a transparent glass substrate  42 . After such procedures, a plurality of protruding metal wires  43  will be formed in the wire-collecting area  411  as illustrated in  FIG. 5B . The active area  41 , the wire-collecting area  411  and the OLB area  412  are electrically connected. The material of the metal wires  43  is usually molybdenum (Mo), aluminum (Al) or the stack of Mo and Al. In general, a protective layer  44 , such as indium tin oxide (ITO) or indium-doped zinc oxide (IZO), is sputtered on the surface of the metal wires  43  in order to prevent from oxidation of the metal wires  43 .  
         [0048]     After the above steps, an organic resin material is formed on the substrate  42  by the spin-coating method. Then, the organic resin material located on the active area  41 , the wire-collecting area  411 , and the OLB area  412  is removed by exposure, development and baking, forming a black matrix (BM) layer  45  in a black matrix area  413  shown in  FIG. 5A . The black matrix area  413  surrounds the active area  41 . Thus, no BM layer  45  remains in the wire-collecting area  411 , that is, no BM layer can be seen from  FIG. 5B .  
         [0049]     The color filter [CF] layer process will be executed after the formation of the BM layer  45 . At present, the main commercial process to form the CF layer is the organic pigment dispersion (OPD) method. A radical polymerization photoresist including organic pigment can be used. The procedures of coating the photoresist, exposure and development are repeated three times to form R, G, and B color filter patterns. We can get the R color filter patterns by using the Anthraquinone series organic pigment and the G, B color filter patterns by using the Phthalocyanine series organic pigment. The R, G, and B color filter patterns can have different variations, provided that at least one color filter pattern remains both in the active area  41  and the wire-collecting area  411  and all the color filter patterns in the OLB area  412  are removed. The color filter pattern remaining in the active area  41  is not shown. The color filter pattern remaining in the wire-collecting area  411  is labeled a color filter layer  46  as a passivation layer as shown in  FIG. 5B . The color filter layer  46  can be single color of red, green, or blue, that is, a red, green, or blue color filter pattern. Or, the color filter layer  46  can be a combination of arbitrary two or three colors, that is, a combination of red and green color filter patterns, a combination of red and blue color filter patterns, a combination of green and blue color filter patterns, or a combination of red, green, and blue color filter patterns. The CF Layer  46  of good moisture-proof and insulation is preferable.  
         [0050]     Please refer to  FIG. 6A  and  FIG. 6B , a front view of the TFT-LCD device and a cross-sectional view of the OLB area according to the third embodiment of the present invention are shown.  FIG. 6B  is the cross-sectional view of  FIG. 6A  in the YY′ direction. First, a series of the procedures forming TFTs, a wire-collecting area  511 , and an outer lead bonding (OLB) area  512  are executed on a transparent glass substrate  52 . After such procedures, a plurality of protruding outer leads  58  will be formed in the OLB area  512  as illustrated in  FIG. 6B . The active area  51 , the wire-collecting area  511  and the OLB area  512  are electrically connected.  
         [0051]     After the above steps, the black matrix [BM] layer process is executed. First, an organic resin material is formed on the substrate by the spin-coating method. Then, the organic resin material in the active area  51  and the wire-collecting area  511  is entirely removed, and that in the OLB area  512  is partially removed by exposure, development and baking, forming a black matrix BM layer  55  in a black matrix area  513  and in the OLB area  512  as illustrated in  FIGS. 6A and 6B . The black matrix area  513  surrounds the active area  51 . The BM layer  55  in the OLB area  512  is located between the outer leads  58  as an insulation layer, in order to increase insulation among said outer leads  58 . The height of the BM layer  55  is preferably lower than the outer leads  58  to avoid that the outer leads  58  are unable to connect electrically with a flexible printed circuit board (FPC). The height of the BM Layer  55  can be from about 0.5 micron to about 3 micron.  
         [0052]     Please refer to  FIG. 6A  and  FIG. 6C , a front view of the TFT-LCD device and a cross-sectional view of the OLB area according to the fourth embodiment of the present invention are shown.  FIG. 6C  is the cross-sectional view of  FIG. 6A  in the YY′ direction. First, a series of the procedures forming TFTs, a wire-collecting area  511 , and an outer lead bonding (OLB) area  512  are executed on a transparent glass substrate  52 . After such procedures, a plurality of protruding outer leads  58  will be formed in the OLB area  512  as illustrated in  FIG. 6C . The active area  51 , the wire-collecting area  511  and the OLB area  512  are electrically connected.  
         [0053]     After the above steps, an organic resin material is formed on the substrate by the spin-coating method. Then, the organic resin material in the active area  51 , the wire-collecting area  511 , and the OLB area  512  is entirely removed by exposure, development and baking, forming a black matrix (BM) layer  55  in a black matrix area  513  as illustrated in  FIG. 6A . The black matrix area  513  surrounds the active area  51 .  
         [0054]     The color filter [CF] layer process will be executed after the formation of the BM layer  55 . At present, the main commercial process to form the CF layer is the organic pigment dispersion (OPD) method. A radical polymerization photoresist including organic pigment can be used. The procedures of coating the photoresist, exposure and development are repeated three times to form R, G, and B color filter patterns. The CF layer in the active area  51  and the OLB area  512  is reserved, while that in the wire-collecting area  511  is removed. The color filter layer remaining in the active area  51  is not shown. The color filter layer remaining in the OLB area  512  is labeled a color filter layer  56  in  FIG. 6C . The color filter layer  56  in the OLB area  512  is disposed between the outer leads  58  as an insulation layer for increasing insulating among the outer leads  58 . The height of the CF layer  56  can be lower than the outer leads  58  to avoid that the outer leads  58  are unable to connect electrically with a flexible printed circuit board (FPC). The height of the CF Layer  56  can be from about 0.5 micron to about 3 micron.  
         [0055]     The color filter layer  56  can be single color of red, green, or blue, that is, a red, green, or blue color filter pattern. Or, the color filter layer  56  can be a combination of arbitrary two or three colors, that is, a combination of red and green color filter patterns, a combination of red and blue color filter patterns, a combination of green and blue color filter patterns, or a combination of red, green, and blue color filter patterns. The CF Layer  56  of good moisture-proof and insulation is preferable.  
         [0056]     Please refer to  FIG. 7A  and  FIG. 7B , a front view of the TFT-LCD device and cross-sectional views of the wire-collecting area and the OLB area according to the fifth embodiment of the present invention are shown.  FIG. 7B  shows the cross-sectional views of  FIG. 7A  in the XX′ and YY′ directions. First, a series of the procedures forming TFTs, a wire-collecting area  611 , and an outer lead bonding (OLB) area  612  are executed on a transparent glass substrate  62 . After such procedures, a plurality of protruding metal wires  63  will be formed in the wire-collecting area  611  and a plurality of protruding outer leads  68  will be formed in the OLB area  612  as illustrated in  FIG. 7B . The active area  61 , the wire-collecting area  611  and the OLB area  612  are electrically connected. The material of the metal wires  63  is usually molybdenum (Mo), aluminum (Al) or the stack of Mo and Al. In general, a protective layer, such as indium tin oxide (ITO) or indium-doped zinc oxide (IZO)  64 , is sputtered on the surface of the metal wires  63  in order to prevent from oxidation of the metal wires  63 .  
         [0057]     After the above steps, the black matrix [BM] layer process will be executed. First, an organic resin material is formed on the substrate  62  by the spin-coating method. Then, the organic resin material is selectively removed by exposure, development and baking to form a BM layer  65 . The BM layer  65  remains in a black matrix area  613  surrounding the active area  61  and in the wire-collecting area  611 , and also remains in part of the OLB area  612  as shown in  FIGS. 7A and 7B . Thus, the wire-collecting area  611  is protected by the BM layer  65  (a passivation layer), thus enhancing product reliability. In addition, the BM layer  65  in the OLB area  612  is located between the outer leads  68  as an insulation layer. Thus, the insulation among the outer leads  68  in the OLB area  612  is increased. Preferably, the height of the BM layer  65  is higher than the sum of the height of metal wires  63  and the height of the protective layer (ITO/IZO)  64 , but lower than the outer leads  68  to avoid that the outer leads  68  are unable to connect electrically with a flexible printed circuit board (FPC). The height of the BM Layer  65  can be from about 0.5 micron to about 3 micron.  
         [0058]     Please refer to  FIG. 8A  and  FIG. 8B , a front view of the TFT-LCD device and cross-sectional views of the wire-collecting area and the OLB area according to the sixth embodiment of the present invention are shown.  FIG. 8B  shows the cross-sectional views of  FIG. 8A  in the XX′ and YY′ directions. First, a series of the procedures forming TFTs, a wire-collecting area  611 , and an outer lead bonding (OLB) area  612  are executed on a transparent glass substrate  62 . After such procedures, a plurality of protruding metal wires  63  will be formed in the wire-collecting area  611  and a plurality of protruding outer leads  68  will be formed in the OLB area  612  as illustrated in  FIG. 8B . The active area  61 , the wire-collecting area  611  and the OLB area  612  are electrically connected. The material of the metal wires  63  is usually molybdenum (Mo), aluminum (Al) or the stack of Mo and Al. In general, a protective layer, such as indium tin oxide (ITO) or indium-doped zinc oxide (IZO)  64 , is sputtered on the surface of the metal wires  63  in order to prevent from oxidation of the metal wires  63 .  
         [0059]     After the above steps, an organic resin material is formed on the substrate  62  by the spin-coating method. Then, the organic resin material located in the active area  61 , the wire-collecting area  611 , and the OLB area  612  is removed by exposure, development, and baking, leaving a black matrix (BM) layer  65  in a black matrix area  613  surrounding the active area  61 .  
         [0060]     The color filter [CF] layer process will be executed after the formation of the BM layer  65 . At present, the main commercial process to form the CF layer is the organic pigment dispersion (OPD) method. A radical polymerization photoresist including organic pigment can be used. The procedures of coating the photoresist, exposure and development are repeated three times to form R, G, and B color filter pattern. We can get the R color filter patterns by using the Anthraquinone series organic pigment and the G, B color filter patterns by using the Phthalocyanine series organic pigment. The R, G, and B color filter patterns can have different variations, provided that at least one color filter pattern remains in the active area  61 , the wire-collecting area  611 , and the OLB area  612 . The color filter layer remaining in the active area  61  is not shown. The color filter layer remaining in the wire-collecting area  611  and the OLB area  612  is labeled a color filter layer  66 . The color filter layer  66  covers the entire wire-collecting area  611 , while the color filter layer  66  in the OLB area  612  is located between the outer leads  68  as an insulation layer. Thus, the wire-collecting area  611  is protected by the CF layer  66  (a passivation layer), thus enhancing product reliability. In addition, the insulation among the outer leads  68  in the OLB area  612  is increased by the presence of the color filter layer  66 .  
         [0061]     The CF layer  66  can be single color of red, green, or blue, that is, a red, green, or blue color filter pattern. Or, the color filter layer  66  can be a combination of arbitrary two or three colors, that is, a combination of red and green color filter patterns, a combination of red and blue color filter patterns, a combination of green and blue color filter patterns, or a combination of red, green, and blue color filter patterns. The CF layer  66  of good moisture-proof and insulation is preferable. The height of the CF layer  66  is preferably higher than the sum of the height of metal wires  63  and the height of the protective layer (ITO/IZO)  64 , but lower than the outer leads  68  to avoid that the outer leads  68  are unable to connect electrically with a flexible printed circuit board (FPC). The height of the CF Layer  66  can be from about 0.5 micron to about 3 micron.  
         [0062]     Although the specific embodiment has been illustrated and described, it will be obvious to those skilled in the art that various modifications may be made without departing from what is intended to be limited solely by the appended claims.