Abstract:
A thin film transistor array panel can include: a substrate; a gate line formed on the substrate; a gate pad formed at an end of the gate line; a gate identification member corresponding to the gate pad and formed in the same layer as the gate pad; a gate insulating layer covering the gate line and the gate identification member; a data line formed on the gate insulating layer; a passivation layer formed on the gate insulating layer and the data line; a gate contact assistant formed on the passivation layer; and a gate driving chip electrically connected to the gate contact assistant, wherein the gate contact assistant at least partially overlaps the gate identification member. The gate identification member is formed without producing a step in the gate contact assistant, reducing the risk of defects when wires or other objects are pressed onto the gate pad.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to, and the benefit of, Korean Patent Application No. 10-2009-0098339 filed in the Korean Intellectual Property Office on Oct. 15, 2009, the entire contents of which are incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    (a) Field of the Invention 
         [0003]    The present invention relates to a thin film transistor array panel. 
         [0004]    (b) Description of the Related Art 
         [0005]    Liquid crystal displays (LCDs) are among the most widely used flat panel displays. A typical LCD includes a pair of panels provided with field-generating electrodes, and a liquid crystal (LC) layer interposed therebetween. The LCD displays images by applying voltages to the field-generating electrodes to generate an electric field in the LC layer. This field orients the LC molecules, which polarizes incident light. 
         [0006]    One widely employed LCD structure utilizes field generating electrodes respectively formed on two display panels. A plurality of pixel electrodes are arranged in a matrix format on one display panel, and one common electrode covers the surface of the other display panel. In the liquid crystal display, each pixel electrode is separately applied with a voltage to display images. A thin film transistor (TFT) is connected to each pixel electrode for switching the voltage applied to the pixel electrode, as well as a plurality of gate lines transmitting signals to control the thin film transistor, and a plurality of data lines transmitting the voltage that is applied to the pixel electrode. 
         [0007]    The thin film transistor array panel is controlled by a driving circuit connected to the gate line and the data line. The driving circuit may be attached to the panel by a tape carrier package (TCP) type structure, or a chip-on-glass (COG) type structure. With the TCP type structure, a tape mounted with the driving chip is separately attached to the thin film transistor array panel, whereas with the COG type structure, the driving chip is directly mounted on an insulation substrate of the thin film transistor array panel. Conventionally, TCP type structures have been more widely used. However, the COG type structure has recently gained popularity due to its smaller footprint and lower cost. Also, TCP type structures typically require an additional circuit for applying signals to their driving circuits. This added circuit must be formed on an additional printed circuit board (PCB), and connected through an additional flexible printed circuit (FPC) film. 
         [0008]    In COG type thin film transistor array panels, to easily confirm a defect in wiring when inspecting for defects, an identification number is given to each gate pad and each data pad (i.e., the pads connected to a gate driving chip and a data driving chip, respectively). 
         [0009]    However, as components have become more highly integrated, the interval between the plurality of gate pads or the plurality of data pads has shrunk to the point that it is difficult to form these identification numbers. 
         [0010]    When an identification number is not formed between the gate pads or the data pads, it is difficult to find and keep track of defective wiring. Also, if the identification number partially overlaps the gate pad and is formed with a different material from the gate pad, a step is generated at the overlap. This partial overlap is more likely to generate defects during pressing of bond wires onto the pads. One approach to overcoming this problem is to form small identification numbers in the narrow spaces between neighboring pads. However, these numbers are often too small to read easily, and also risk shorting their adjacent pads to each other. 
         [0011]    The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention. Therefore, it may contain information not in the prior art and not already known to a person of ordinary skill in the art. 
       SUMMARY OF THE INVENTION 
       [0012]    The present invention easily executes defect inspection and prevents defects in a press process between the pad and the driving chip. 
         [0013]    A thin film transistor array panel according to an exemplary embodiment of the present invention includes: a substrate; a gate line formed on the substrate; a gate pad formed at an end of the gate line; a gate identification member corresponding to the gate pad and formed in the same layer as the gate pad; a gate insulating layer covering the gate line and the gate identification member; a data line formed on the gate insulating layer; a passivation layer formed on the gate insulating layer and the data line; a gate contact assistant formed on the passivation layer; and a gate driving chip electrically connected to the gate contact assistant, wherein the gate contact assistant at least partially overlaps the gate identification member. 
         [0014]    A contact hole may be formed in the gate insulating layer and the passivation layer, and the gate pad may be connected to the gate contact assistant through the gate contact hole. 
         [0015]    The gate identification member may comprise the same material as the gate pad. 
         [0016]    The gate identification member may comprise an identification number. 
         [0017]    The gate identification member may be oriented along a major axis of the gate pad. 
         [0018]    A data contact assistant formed on the passivation layer and a data identification member corresponding to the data pad and formed in the same layer as the data pad may be further included, wherein the data contact assistant at least partially overlaps the data identification member. 
         [0019]    A data driving chip electrically connected to the data contact assistant may be further included, and the passivation layer may have a data contact hole formed therein. 
         [0020]    The data pad may be connected to the data contact assistant through the data contact hole. 
         [0021]    The data identification member may comprise the same material as the data pad. 
         [0022]    The data identification member may comprise an identification number. 
         [0023]    The data identification member may be oriented along a major axis of the data pad. 
         [0024]    A thin film transistor array panel according to another exemplary embodiment of the present invention includes: a substrate; a gate line formed on the substrate; a gate insulating layer formed on the gate line: a data line formed on the gate insulating layer; a passivation layer formed on the gate insulating layer and the data line; a data contact assistant formed on the passivation layer; and a data identification member close to the data pad and formed with the same layer as the data pad, wherein the data contact assistant at least partially overlaps the data identification member. 
         [0025]    According to the present invention, a gate identification member is formed without producing a step in a corresponding gate contact assistant, thus reducing the risk of defects when wires or other objects are pressed onto the gate pad. 
         [0026]    Also, a data identification member is formed without producing a step in a corresponding data contact assistant, thus reducing the risk of defects when wires or other objects are pressed onto the data pad. 
         [0027]    Further, the identification number is not formed between the gate pads or the data pads, reducing the risk that neighboring pads will be shorted to each other. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]      FIG. 1  is a top plan view showing a schematic structure of a thin film transistor array panel according to an exemplary embodiment of the present invention. 
           [0029]      FIG. 2  is an enlarged layout view a gate pad shown in  FIG. 1 . 
           [0030]      FIG. 3  is a cross-sectional view taken along the line III-III in  FIG. 2 . 
           [0031]      FIG. 4  is an enlarged layout view a data pad shown in  FIG. 1 . 
           [0032]      FIG. 5  is a cross-sectional view taken along the line V-V in  FIG. 4 . 
       
    
    
       [0033]    Like reference numerals refer to corresponding parts throughout the drawings. 
       DETAILED DESCRIPTION OF EMBODIMENTS 
       [0034]    The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. 
         [0035]    In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. Like reference numerals designate like elements throughout the specification. It will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. 
         [0036]    Now, a thin film transistor array panel according to an exemplary embodiment of the present invention will be described with reference to accompanying drawings. 
         [0037]      FIG. 1  is a top plan view showing a schematic structure of a thin film transistor array panel according to an exemplary embodiment of the present invention. 
         [0038]    As shown in  FIG. 1 , the thin film transistor array panel is divided into a display area  10  displaying images inside a dotted line, and a non-display area  20  outside the dotted line. 
         [0039]    In the display area  10 , a plurality of gate lines  121  and data lines  171  are formed. The gate lines  121  and the data lines  171  are crossed, thereby defining pixel areas P. Although not shown, a thin film transistor is positioned where the gate lines  121  and the data lines  171  cross. The thin film transistor switches a signal applied to a pixel electrode of the display area, thereby displaying images. 
         [0040]    In the non-display area  20 , gate pads  129  and data pads  179  are formed and connected, respectively, to the ends of the gate lines  121  and the data lines  171 . The gate pads  129  and the data pads  179  are connected to a gate driving chip  400  and a data driving chip  500 , respectively. The data driving chip  500  is mounted on the non-display area  20 . The gate driving chip  400  and the data driving chip  500  are each connected to one or more external printed circuit boards (PCBs) (not shown), through FPC films  600  and  700 . The printed circuit board PCB(s) include a plurality of elements such as ICs formed thereon, thereby generating various control signals and data signals to drive the liquid crystal display. Here, the printed circuit board PCB(s) are divided into gate units and data units. These gate and data units are respectively connected to each other through the FPC films  600  and  700 , such that the gate signals are transmitted to the gate driving chip  400  and the data signals are transmitted to the data driving chip  500 .  FIG. 2  is an enlarged layout view of one of the gate pads shown in  FIG. 1 , and  FIG. 3  is a cross-sectional view taken along the line III-III in  FIG. 2 . 
         [0041]    As shown in  FIG. 2  and  FIG. 3 , a plurality of gate lines  121 , gate pads  129 , and gate identification members  125  are each formed on an insulation substrate  100 , which is made of transparent glass or plastic, in the non-display area  20 . 
         [0042]    The gate lines  121  are formed in the display area  10 , but each has an expansion that is extended to the non-display area  20 . More specifically, a plurality of gate pads  129  maintaining a predetermined interval d are connected to the ends of the plurality of gate line  121 . These gate pads  129  have a greater width than that of their respective gate lines  121 , facilitating easier contact with the gate driving chip  400 . The gate pad  129  includes a contact hole  181  for contact with the terminal of the gate driving chip  400 , and a probe contact portion  127  for contact with the tip of a probe used in defect inspection. 
         [0043]    The gate identification member  125  is formed relatively close to the gate pad  129 , along the major axis of the gate pad  129 . The gate identification member  125  may be formed of the same material as the gate pad  129 , and the gate lines  121 , the gate pads  129 , and the gate identification member  125  may be made of a metal such as an aluminum-containing metal of aluminum (Al) or an aluminum alloy, a silver-containing metal of silver (Ag) or a silver alloy, a copper-containing metal of copper (Cu) or a copper alloy, a molybdenum-containing metal of molybdenum (Mo) or a molybdenum alloy, chromium (Cr), tantalum (Ta), and titanium (Ti). 
         [0044]    When detecting a defective pixel, if the gate identification members  125  are not present, the gate lines  121  must typically be counted from the start, making the defect inspection process time-consuming and overly difficult. The gate identification members  125  are formed and placed so as to allow for ready identification of the pads, so as to substantially solve this problem. 
         [0045]    The gate identification member  125  can be formed at any distance from its corresponding gate pad, so long as it can still be readily identified with its gate pad. Further, while each gate identification member  125  is shown in  FIG. 2  as lying parallel to, and along, the major axis of its corresponding gate pad, the invention contemplates any orientation and position of each member  125 , so long as the members  125  are readily associated with their corresponding pads. 
         [0046]    The gate identification member  125  can be formed as a number, a symbol, or any other unique identifier for each gate line  121 , allowing for one to more easily obtain information during defect inspection. 
         [0047]    A gate insulating layer  140  is formed on the gate line  121 , the gate pad  129 , and the gate identification member  125 . The gate insulating layer  140  can be made of silicon nitride (SiNx), silicon oxide (SiO 2 ), or any other suitable insulating material. 
         [0048]    A passivation layer  180  is formed on the gate insulating layer  140 . The passivation layer can be any suitable organic or inorganic insulator. The gate insulating layer  140  and the passivation layer  180  have a contact hole  181  formed therein, exposing a portion of the gate pad  129  of the gate line  121 . 
         [0049]    A gate contact assistant  195  is formed on the passivation layer  180 , and is connected to the gate pad  129  of the gate line through the contact hole  181 . The gate contact assistant  195  overlaps the gate pad  129  and the gate identification member  125 . The gate contact assistant  195  is placed in electrical contact with the gate driving chip  400 , so as to apply the gate driving signal to the gate line  121 . While the gate contact assistant  195  is shown here as overlapping the entirety of the gate identification member  125 , the invention is not limited to any such configuration, and includes embodiments in which the gate contact assistant only partially overlaps the gate identification member  125 . 
         [0050]    As described above, the gate identification member  125  is made of the same material, and in the same layer, as the gate pad  129 . Member  125  also lies under the gate contact assistant  195 , allowing the gate identification member  125  to be made relatively large. Accordingly, the gate identification member  125  may be easily confirmed from the outside during defect inspection. Also, as the members  125  are not formed between neighboring gate pads  129 , the members  125  do not significantly increase the risk of shorting neighboring pads to each other. 
         [0051]    The above configurations of gate identification members  125  can be equally applied to data pads  179 . To that end,  FIG. 4  illustrates an enlarged layout view a data pad shown in  FIG. 1 , and  FIG. 5  is a cross-sectional view taken along the line V-V in  FIG. 4 . 
         [0052]    As shown in  FIG. 4  and  FIG. 5 , the gate insulating layer  140  is formed on the insulation substrate  100 , and can be made of silicon nitride (SiNx) or silicon oxide (SiO 2 ). The insulation substrate  100  can be made of transparent glass or plastic at the non-display area  20 . 
         [0053]    A plurality of data lines  171 , data pads  179 , and data identification members  175  are formed on the gate insulating layer  140 . 
         [0054]    The data lines  171  are formed in the display area  10 , but each has an expansion formed in the non-display area  20  for electrically connecting the data pads  179  and the data lines  171  to the data unit(s). Data pads  179  are formed on the ends of the data lines  171 . Neighboring data pads  179  are formed with a predetermined interval d therebetween. The data pads  179  are wider than the data lines  171 , facilitating easier contact with the data driving chip  400 . Also, the data identification members  175  are formed relatively close to the data pads  179 , along the major axis of the data pads  179 . The data identification members  175  may be made of the same material as the data pads  179 , and the data lines  171  may be made of a metal such as an aluminum-containing metal of aluminum (Al) or an aluminum alloy, a silver-containing metal of silver (Ag) or a silver alloy, a copper-containing metal of copper (Cu) or a copper alloy, a molybdenum-containing metal of molybdenum (Mo) or a molybdenum alloy, chromium (Cr), tantalum (Ta), and titanium (Ti). 
         [0055]    The data identification member  175  is formed as a number, a symbol, or any other unique identifier for each data line  171  that allows for one to more readily obtain information during defect inspection. 
         [0056]    A passivation layer  180  made of an inorganic insulating layer or an organic insulator is formed on the data lines  171 , the data pads  179 , and the data identification members  175 . The passivation layer  180  can be made of an inorganic insulating layer or an organic insulator, and has a contact hole  182  exposing a portion of the data pad  179  of the data line  171 . 
         [0057]    A data contact assistant  196  is formed on the passivation layer  180 , and is connected to the data pad  179  of the data line  171  through the contact hole  182 . The data contact assistant  196  overlaps the data pad  179  and the data identification member  175 . The data contact assistants  196  are electrically connected to the data driving chip  500 , thereby applying the data driving signal to the data line  171 . While the data contact assistant  196  is shown here as overlapping the entirety of the data identification member  175 , the invention is not limited to any such configuration, and includes embodiments in which the data contact assistant only partially overlaps the data identification member  175 . 
         [0058]    As described above, the data identification member  175  can be made of the same material, and in the same layer as, the data pad  179 , and overlaps the data contact assistant  196  such that the data identification member  175  may be made relatively large. Accordingly, the data identification member  175  may be easily confirmed from the outside during defect inspection. Also, as the members  175  are not formed between neighboring data pads  179 , the members  175  do not significantly increase the risk of shorting neighboring pads to each other. 
         [0059]    While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.