Abstract:
Provided are an organic EL display device and a method of manufacturing the organic EL display device for preventing damage caused in a process of exposing terminals and for improving light extraction from the display. A glass substrate is removed from a panel that is formed by sequentially laminating a TFT substrate, a sealing film, a flexible substrate layer, and the glass substrate. A portion of the flexible substrate layer is removed that is formed on a position corresponding to a terminal part of the TFT substrate. A transparent thin film is formed on the flexible substrate layer, and a portion of the sealing film is removed by using the transparent thin film as a mask. The portion of the sealing film is formed on the position corresponding to the terminal part of the TFT substrate.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority from Japanese Application JP2015-218940 filed on Nov. 6, 2015. This application is hereby incorporated by reference into this application. 
       BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
       [0002]    The present invention relates to a method of manufacturing an organic electroluminescence (EL) display device and the organic EL display device. 
       2. Description of the Related Art 
       [0003]    As disclosed in JP2009-205941A, for example, a flexible display includes an organic EL layer formed on a thin film transistor (TFT) substrate on which a TFT is formed. In order to protect such organic EL layer from moisture, for example, the organic EL layer is covered by a sealing film. Here, terminals formed on a display (the terminals are connections with external terminals) are exposed by etching a portion of the sealing film that is formed over the terminals to remove the portion. 
       SUMMARY OF THE INVENTION 
       [0004]    However, when a flexible substrate formed on the sealing film functions as a mask in the etching process for exposing the terminals, the flexible substrate can be damaged and problems such as reduced light extraction efficiency and deteriorated organic EL layers may occur. 
         [0005]    One or more embodiments of the present invention have been conceived in view of the above, and an object thereof is to provide an organic EL display device and a method of manufacturing the organic EL display device for preventing damage caused in a process of exposing terminals and for improving light extraction from the display. 
         [0006]    (1) A method of manufacturing an organic EL display device according to the present invention includes 
         [0007]    removing a glass substrate from a panel that is formed by sequentially laminating a TFT substrate, a sealing film covering the TFT substrate, a flexible substrate layer covering the sealing film, and the glass substrate, wherein the TFT substrate has a laminated structure and a plural y of transistors formed on the TFT substrate, and the laminated structure has a first electrode, an organic EL layer, and a second electrode that are laminated therein; 
         [0008]    removing a portion of flexible substrate layer, wherein the portion is formed on a position corresponding to a terminal part of the TFT substrate; 
         [0009]    forming a transparent thin film on the flexible substrate layer; and 
         [0010]    removing a portion of the sealing film by using the transparent thin film as a mask, wherein the portion is formed on the position corresponding to the terminal part of the TFT substrate. 
         [0011]    (2) In the method of manufacturing the organic EL display device as described in the above (1), the transparent thin film may be formed on the flexible substrate layer after the portion of the flexible substrate layer is removed. 
         [0012]    (3) in the method of manufacturing the organic EL display device as described in the above (1), the transparent thin film may include a portion formed on the portion of the flexible substrate layer; and the portion of the flexible substrate layer and the portion of the transparent thin film may be removed together. 
         [0013]    (4) Another method of manufacturing an organic EL display device according to the present invention includes 
         [0014]    forming a panel by sequentially laminating a TFT substrate, a sealing film covering the TFT substrate, a flexible substrate layer covering the sealing film, a transparent thin film, and a glass substrate, wherein the TFT substrate has a laminated structure and a plurality of transistors formed on the TFT substrate, and wherein the laminated structure has a first electrode, an organic EL layer, and a second electrode that are laminated therein; 
         [0015]    removing the glass substrate from the panel; 
         [0016]    removing a portion of the flexible substrate layer and a portion of the transparent thin film respectively, wherein the portions of the flexible substrate layer and the transparent thin film are formed on a position corresponding the terminal part of the TFT substrate; and 
         [0017]    removing a portion of the sealing film by using the transparent thin film as a mask, wherein the portion of the sealing film is formed on the position corresponding to the terminal part of the TFT substrate. 
         [0018]    (5) In the method of manufacturing the organic EL display device described in any one of the above (1) to (4), the sealing film may be removed by etching. 
         [0019]    (6) in the method of manufacturing the organic EL display device described in any one of the above (1) to (5), the flexible substrate layer may be a polyimide layer. 
         [0020]    (7) An organic EL display device according to the present invention includes a TFT substrate on which a laminated structure of a first electrode, an organic EL layer, and a second electrode is disposed and a plurality of transistors are formed, a sealing film covering the TFT substrate, a flexible substrate layer covering the sealing film, and a transparent thin film formed on a predetermined position other than a position corresponding to a terminal part of the TFT substrate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a schematic diagram illustrating an organic EL display device; 
           [0022]      FIG. 2  illustrates an example of a circuit of the organic EL display device; 
           [0023]      FIG. 3  illustrates an example of a sectional view of a part of the organic EL, display device; 
           [0024]      FIG. 4A  is a diagram illustrating a manufacturing method of the organic EL display device according to the first embodiment; 
           [0025]      FIG. 4B  is a diagram illustrating a manufacturing method of the organic EL display device according to the first embodiment; 
           [0026]      FIG. 4C  is a diagram illustrating a manufacturing method of the organic EL display device according to the first embodiment; 
           [0027]      FIG. 4D  is a diagram illustrating a manufacturing method of the organic EL display device according to the first embodiment; 
           [0028]      FIG. 5A  is a diagram illustrating a manufacturing method o the organic EL display device according to the second embodiment; 
           [0029]      FIG. 5B  is a diagram illustrating a manufacturing method of the organic EL display device according to the second embodiment; 
           [0030]      FIG. 5C  is a diagram illustrating a manufacturing method of the organic EL display device according to the second embodiment; and 
           [0031]      FIG. 5D  is a diagram illustrating a manufacturing method or the organic EL display device according to the second embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]      FIG. 1  is a schematic diagram illustrating an organic EL display device. The organic EL display device  10  controls each pixel formed on a display area  11  on a substrate  100  with use of a data driving circuit  12  and a scan driving circuit  13  to display an image. For example, the data driving circuit  12  is an IC (Integrated Circuit) that generates and transmits a data signal to each pixel, and the scan driving circuit  13  is an IC that generates and transmits a gate signal to a TFT (Thin Film Transistor) provided in each pixel. In  FIG. 2 , the data driving circuit  12  and the scan driving circuit  13  are formed at two locations, although they may be incorporated into one IC, or formed with a circuit formed directly on the substrate  100 . 
         [0033]    As shown in  FIG. 1 , each of scanning lines  14  for transmitting signals from the scan driving circuit  13  is connected to gate electrodes of switching transistors  30 . Each of data lines  15  for transmitting signals from the data drive circuit  12  is connected to a source/drain electrode of the switching transistors  30 . Each of electric potential lines  16  is applied with a reference electric potential for making organic light emitting diodes  60  emit light, and connected to a source/drain electrode of driver transistors  20 . A first electric potential supply line  17  and a second electric potential supply line  18  are connected to an electric potential supply source, and connected to the electric potential line  16  through respective transistors. In this regard, the configuration illustrated in  FIG. 1  is an example, and the present embodiment is not to be limited to the above described example. 
         [0034]      FIG. 2  illustrates an example of a circuit of the organic EL display device according to the present embodiment. The display area  11  of the organic EL display device  10  has data lines  15  and scanning lines  14  each formed therein. The data lines  15  include a first line (D 1 ) to a n-th line (Dn), and the total number of the data lines is n. The scanning lines  14  include a first line (G 1 ) to a m-th line (Gm), and the total number of the scanning lines is m. Plural pixels PX are arranged in a matrix and arrayed in an extension direction of the scanning lines  14  and in an extension direction of the data lines  15 . For example, a pixel PX is formed in an area surrounded by G 1  and G 2 , and D 1  and D 2 . 
         [0035]    The first scanning line G 1  is connected to a gate electrode of a switching transistor  30 . When a signal is supplied from the scan driving circuit  13 , the switching transistor  30  turns on. In this state, when a signal is supplied to the first data line D 1  from the data drive circuit  12 , electric charge is stored in a storage capacitor  40 , a voltage is applied to the gate electrode of a driver transistor  20 , and the driver transistor  20  turns on even when the switching transistor  30  is in an OFF state, the driver transistor  20  stays in an ON state for a given period due to the electric charge stored in storage capacitor  40 . The anode of the organic light emitting diode  60  is connected to the electric potential line  16  through the source and the drain of the driver transistor  20 , and the cathode of the organic light emitting diode  60  is fixed to a reference electric potential Vc. As such, electric current according to the gate voltage of the driver transistor  20  flows into the organic light emitting diode  60 , and the organic light emitting diode  60  emits light. Further, an additional capacitor  50  is formed between the anode and the cathode of the organic light emitting diode  60 . The additional capacitor  50  provides an advantage of stabilizing a voltage applied to the storage capacitor  40 , and contributes to stable operation of the organic emitting diode  60 . The capacitance of the additional capacitor  50  is set to be larger than the capacitance of the storage capacitor  40 , which provides the advantage described above. 
         [0036]      FIG. 3  illustrates an example of a partial cross section of the organic EL display device. As shown in  FIG. 3 , a first polyimide layer  301  has a foundation layer  308  formed thereon. Further, the first polyimide layer  301  provided with gate electrodes of the switching transistors  30 , gate electrodes of the driver transistors  20 , and pixel electrodes (anodes)  302 . In the example of  FIG. 3 , those are formed on the foundation layer  308 . Further, a gate insulating film  303  is formed covering the gate electrodes of the switching transistors  30  and the gate electrodes of the driver transistors  20 . An organic EL layer  304  is formed on the pixel electrodes  302 , and a common electrode  305  (cathode) is formed on the organic EL layer  304 . The source/drain electrodes and the channel layer of each switching transistor  30  are formed on the gate insulating film  303 . One of the source/drain electrodes of each switching transistor  30  is connected to the gate electrode of the driver transistor  20 . The source/drain electrode of the driver transistor  20  is connected to the pixel electrode  302 . A protective film  306  is formed on the source/drain electrodes of the switching transistors  30  and the driver transistors  20 . A sealing film  307  is formed on the common electrode  305 . A second lyimide layer (not shown) is formed on the sealing film  307 . The cross-sectional configuration described above is an example and the present embodiment is not limited to the example. For example, a plastic substrate may be used in place of the first and/or second polyimide layer  301 . 
         [0037]    Next, referring to  FIGS. 4A to 4D , a method of manufacturing the organic EL display device according to the present embodiment will be discussed. The manufacturing method of general organic EL display devices is well known, and thus their explanation will be omitted. The following main discusses a process of exposing terminals in a terminal part  504  of a TFT substrate  503  in the manufacturing method of the organic EL display device according to the present embodiment  FIGS. 4A to 4D  show a cross-section of the organic EL display device  10  and do not show the first glass substrate  501  and the second glass substrate  502 . Specifically,  FIGS. 4A to 4D  show only the TFT substrate  503  on which TFT (e.g., switching transistors  30  and driver transistor  20 ) is formed, the organic EL layer  304 , the sealing film  307 , and the polyimide layer  301 . In the following, a structure in which the first glass substrate  501  and the second glass substrate  502  are respectively formed on the top and the bottom of the organic EL display device  10  is referred to as “panel”. The first polyimide layer  505  and the second polyimide layer  506  respectively correspond to the first polyimide layer  301  and the second polyimide layer (not shown in  FIG. 3 ) described by referring to  FIG. 3 . The polyimide layers  505  and  506  are flexible substrate layers. 
         [0038]    As shown in  FIG. 4A , the second glass substrate  502  s removed from the panel by irradiating a laser to the panel. Subsequently, as shown in  FIG. 4B , a portion of the second polyimide layer  506  that is formed over the terminal part  504  of the TFT substrate  503  is removed by a laser. As shown in  FIG. 4C , a transparent flexible thin film  507  is then formed on an area other than the terminal part  504 . As illustrated by arrows in  FIG. 4C , a portion of the sealing film  307  that is formed over the terminal part  504  is removed by dry etching or wet etching in which the transparent flexible thin film  507  is used as a mask. Here, the material of the transparent flexible thin film  507  and the material of the sealing film  307  are configured so as to secure etch selectivity. That is, the transparent flexible thin film  507  employees a material that allows the sealing film  307  to be selectivity removed. As such, the sealing film  307  is more preferentially removed than the transparent flexible thin film  507 . This enables to expose the terminals in the terminal part  504  of the TFT substrate  503  included in the panel. 
         [0039]    Next, as shown in  FIG. 4D , the first glass substrate  501  is removed from the panel by irradiating a laser to the panel. As shown in  FIGS. 4C and 4D , the transparent flexible thin film  507  may sometimes remain on the second polyimide layer  506 . However, the transparent flexible thin film  507  is transparent, and thus can prevent the light extraction efficiency of the panel or the like from being decreased. 
         [0040]    The process of exposing the terminals described above may be executed, for example, on a large-sized panel that includes a plurality of the panels, or on the individual panel. When the process of exposing the terminals is executed on the large-sized panel, the large-sized panel needs to be divided into the individual panels at the end of the process. The process of exposing the terminals described above is an example, and the present embodiment is not limited to this example and may be configured as described in a variation below, for example. 
       [Variation] 
       [0041]    Next, a variation of the present embodiment will be discussed. In this variation, similarly to the first embodiment, the second glass substrate  502  is removed from the panel by irradiating the laser to the panel. Subsequently, a transparent flexible thin film  507  is formed on a second polyimide layer  506 , including a portion formed over the terminal part  504 . Subsequently, a portion of the second polyimide layer  506  that is formed over the terminal part  504  is removed with the laser. The order of forming the flexible than film  507  is different from that of the first embodiment. That is, in contrast to the first embodiment, the transparent flexible thin film  507  is formed on the second polyimide layer  506 , and thereafter the portion of the second polyimide layer  506  is removed. In this variation, as described above, the transparent flexible thin film  507  is also formed on the second polyimide layer  506 . Accordingly, both of the portions of the transparent flexible thin film  507  and the second polyimide layer  506  are removed with the laser. In the next process, the portion of the sealing film  307  that is located over the terminal part  504  is removed by dry etching or wet etching in which the transparent flexible thin film  507  is used as a mask. Subsequently, the first glass substrate  501  is removed by irradiating a laser to the panel. In this regard, similarly to the first embodiment, the process of exposing the terminals maybe executed, for example, on a large-sized panel that includes a plurality of the panels, or on the individual panel. 
       Second Embodiment 
       [0042]    Next, the second embodiment of the present invention will be discussed. As shown in  FIGS. 5A to 5D , the present embodiment is different from the first embodiment in that a transparent flexible thin film  507  is formed in advance between the second glass substrate  502  and the second polyimide layer  506 . For this reason, the process of exposing the terminals is also different from that of the first embodiment. In the following, regarding the same points as the first embodiment, their overlapping explanation will be omitted. 
         [0043]      FIGS. 5A to 5D  illustrate the process of exposing the terminals in the present embodiment. As shown in  FIG. 5A , the second glass substrate  502  is removed by irradiating a laser to the panel. Subsequently, as shown in  FIG. 5B , a portion of the second polyimide layer  506  that formed over the terminal part  504  is removed with a laser together with a portion of the transparent flexible thin film  507  formed on the portion of the second polyimide layer  506 . In this way, the sealing film  307  over the terminal part  504  is exposed. 
         [0044]    Next, the portion of the sealing film  307  that is formed on the terminal part  504  is removed by dry etching or wet etching in which the transparent flexible thin film  507  is used as a mask. As shown in  FIG. 5D , the first glass substrate  501  is then removed with a laser. 
         [0045]    Similarly to the first embodiment, the process of exposing the terminals described above may be executed, for example, on a large-sized panel including a plurality of the panels, or on the individual panel. 
         [0046]    The present invention is not limited to the above described embodiments and may be modified in various manners. For example, the configurations of the embodiments described above may be replaced by configurations that are substantially the same as those of the above-described embodiments, bring about substantially the same effects as those of the above-described embodiments, or achieve substantially the same objects as those of the above-described embodiments. A transparent thin film in the claims corresponds, for example, the transparent flexible thin film  507  described above.