Abstract:
A method for manufacturing an electrode plate with improved reliability, comprising: (a) providing a glass substrate; (b) spreading an Indium Tin Oxide (ITO) layer on a specific area of the glass substrate; (c) exposing and developing the ITO layer; and (d) screen printing at least a thick film conductive layer on the ITO layer.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates to a method of manufacturing an electrode plate, more particularly to a method of manufacturing an electrode plate by using a process of thick film screen printing.  
       BACKGROUND OF THE INVENTION  
       [0002]     The luminescence principle of a field emission display is that using an electric field in a vacuum condition to attract out electrons at material tips thus the field emission electrons leaving the cathode plate, being accelerated by a positive voltage on the anode plate and hitting the phosphor powders on the anode plate to emit light, and the electrons received on the electrode plate returning to the circuit via the conductive part of the electrode plate. When the display is required to increase the voltage to produce more electrons to hit the phosphor powders and result in brighter luminescence or when the luminescence area of the display increases, the conductive part which collects electrons flow on the electrode plate can not bear and will break down such that the electrons can not flow into the display and the display will be invalidated. Therefore, the design for an electrode plate regarding whether the display can sustain high electrons flow is an important issue.  
         [0003]     In prior arts, the above-mentioned defect was avoided by plating a metal, e.g. chromium, on the sealing part as a conducting layer such that the metal and Indium Tin Oxide (ITO) can conduct voltages into the display. However, the prior arts used a thin film process so that the thickness of the metal layer and the ITO layer is insufficient for high electronics flow and causes the display to break down.  
         [0004]     Please refer to  FIG. 1  for a prior art electrode plate. A glass substrate  21  of an electrode plate  2  is plated with a conducting layer  25  and a frame pattern is plated on the conducting layer  25  besides the areas of a luminescence material  24 . However, the material of the frame pattern is not conductive and the frame pattern is manufactured by a thin film process so that the frame pattern has no effect of reducing current density. The frame pattern is usually black and its main function is to enhance the light contrast, i.e. using the frame pattern as a black background to cause the luminescence material  24  to be clearer. Thus, the conductivity of the conducting layer  25  is still insufficient such that the conducting layer  25  will break down and broken lines  26   a  and  26   b  will occur when the current is too large. For example, a 10″ panel will occur broken lines after 1 minute with a conducted voltage of 2500 volts and a maximum current of 20 μA.  
         [0005]     In view of the prior art electrode plate, how to improve the electrode reliability of an electrode plate so as to increase the luminescence area of the display has become a problem to be resolved in the industry.  
       SUMMARY OF THE INVENTION  
       [0006]     The primary objective of the present invention is to provide a method of manufacturing an electrode plate with improved reliability. The method can improve reliability of an electrode plate such that the conductive part of the electrode plate will not break down and surroundings of the luminescence material of the electrode plate will not occur damages or broken lines when high current density is led into the electrode plate.  
         [0007]     To achieve the foregoing objective, the method of manufacturing an electrode plate with improved reliability comprises the following steps: (a) providing a glass substrate; (b) spreading an Indium Tin Oxide (ITO) layer on a specific area of the glass substrate; (c) exposing and developing the ITO layer; and (d) spreading at least a thick film conductive layer on the ITO layer. In which, the step of spreading a thick film conductive layer is processed by a thick film screen printing process so that the manufactured thickness of the thick film conductive layer can sustain high current density without damages.  
         [0008]     To make the examiner easier to understand the objective, structure, innovative features, and function of the invention, preferred embodiments together with accompanying drawings are illustrated for the detailed description of the invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]      FIG. 1  is a top-view diagram of a prior art electrode plate.  
         [0010]      FIG. 2A  is a top-view diagram of an electrode plate with improved reliability of the present invention.  
         [0011]      FIG. 2B  is a cross sectional diagram of an electrode plate with improved reliability of the present invention.  
         [0012]      FIG. 3  is a flowing chart of manufacturing an electrode plate with improved reliability of the present invention.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0013]      FIG. 2A  and  FIG. 2B  is a top-view diagram and a cross sectional diagram of an electrode plate with improved reliability of the present invention, respectively, wherein the electrode plate  1  is a non-backlight anode plate which comprising a glass substrate  11 , an ITO layer  12 , a thick film conductive layer  13 , a luminescence material  14  and a metal layer  16 . The ITO layer  12  is stacked on an area  111  of the glass substrate  11  and the metal layer  16  is stacked on the ITO layer  12 . The thick film conductive layer  13  is spread on the metal layer  16  and the luminescence material  14  is stacked on an area  112  of the glass substrate  11 , wherein the area  111  and the area  112  are independent and non-overlapped ones. The ITO layer  12  and the metal layer  16  form the conductive layer  15 .  
         [0014]      FIG. 3  is a flowing chart of manufacturing an anode plate according to the present invention. The anode plate manufacturing process  3  comprises steps  31 - 37 , wherein step  31  is a step of providing a glass substrate; step  32  is a step of spreading an ITO layer on a specific area of the glass substrate, in which the ITO layer is used as an electrode; step  33  is a step of exposing and developing the ITO layer; step  34  is a step of spreading a metal layer on the ITO layer; step  35  is a step of exposing and developing the metal layer; step  36  is a step of spreading a thick film conductive layer on the metal layer by screen printing or screen printing with exposing and developing; and step  37  is a step of spreading a luminescence material on a luminescence area besides the specific area.  
         [0015]     In a preferred embodiment of the present invention, the metal layer is a chromium (Cr) layer which thickness is 400 nm and is manufactured by a thin film process. The thickness of the ITO layer is 400 nm and is also manufactured by the thin film process. The luminescence material is phosphor powders and the screen printed thickness, which is 3-20 μm in general, depends on the size of the phosphor powders and the viscosity of the slurry. The thick film conductive layer is a silver (Ag) layer and is spread on the metal layer by a thick film screen printing process. Therefore, the thickness of the thick film conductive layer is larger than 1 μm thus it can sustain larger current density. Certainly, the thick film conductive layer can be made of any conductive material capable of been used to drive the display and is not limited to metal materials.  
         [0016]     In another preferred embodiment of the present invention, the metal layer (Cr) is not required when the electrode plate is used as a backlight anode plate. Therefore, the reliability of the anode plate can be improved by spreading the thick film conductive layer (Ag) on the ITO layer directly. In such situation, the anode plate manufacturing process  3  can omit steps  34  and  35  and the thick film conductive layer is spread on the ITO layer directly in step  36 .  
         [0017]     When the invention is applied for manufacturing an electrode plate used in a 4″ backlight display panel, in general conditions, the voltage still can be conducted into the panel and the thick film conductive layer (Ag) has no strange change after 10 minutes with a voltage of 1000 volts and a current of 20 μA. In an extreme experiment condition, in which the voltage is 10000 volts and the maximum current is 100 μA, electric arcs will occur and the voltage still can be conducted into the panel after 10 minutes. There is only some burned black made by the electric arcs occurring on the thick film conductive layer (Ag) contacting with the electrode. Therefore, the invention can indeed achieve the effect of improving the reliability of an electrode plate.  
         [0018]     While the preferred embodiments of the invention have been set forth for the purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.