Patent Publication Number: US-9887215-B2

Title: Display module manufacturing method and display module

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a manufacturing method of a substrate for display module. Particularly, the present invention relates to a manufacturing method of substrate for thin-type display module. 
     2. Description of the Prior Art 
     Display devices have been extensively applied to various electrical products including computer, television, and communication devices; in addition, the display devices are getting small, thin and light due to the advancement of industrial technology and the user demand. Apart from the usual plane-surface character, display panels nowadays further have curved or flexible feature and go with variable display device designs, or provided for display device development. The display device itself may namely be the major part and accompanied with functions such as word processing, communication and data processing. 
     With regard to the manufacture of flexible display panel/display device, it is generally to form or cut a flexible substrate first (wherein forming the flexible substrate includes coating on a glass plate without cutting), then to dispose circuits, illumination material and/or light sources on the substrate. However, the flexible substrate itself may not be suitable for the high-temperature manufacturing process; accordingly, inflexible sheet materials may be required to serve as a carrier of the flexible substrate. After the manufacturing process is completed, releasing of the flexible substrate from the carrier is conducted by high-energy laser. However, heat and gas which accompany high-energy laser in the releasing process may cause the deformation of the substrate that changes the pitch of the bonding pads in the fan-out area and raises the difficulty of the following processes. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a display module substrate which has less deformation. 
     It is another object of the present invention to provide a manufacturing method of a display module which alleviates the deformation of product and improves the yield of product. 
     The display module substrate of the present invention includes a substrate body and a plurality of signal circuits. The substrate has a supporting surface. The supporting surface includes a viewing area and a signal circuit area on one side of the viewing area. The signal circuits are disposed on the supporting surface and located at the signal circuit area. The signal circuit area has a plurality of apertures running through the substrate body, wherein the apertures are not shielded by the signal circuits. 
     The manufacturing method of the display module substrate of the present invention includes (a) disposing a substrate body on a transparent carrier plate; wherein the substrate body has a bottom surface and a supporting surface opposite to the bottom surface, the bottom surface is attached to the transparent carrier plate, the supporting surface includes a viewing area and a signal circuit area; (b) disposing a plurality of signal circuits in the signal circuit area; (c) forming a plurality of apertures in the signal circuit area, the apertures running through the substrate body and not shielded by the signal circuits; (d) etching the bottom surface by high-energy light through the transparent carrier plate to separate the substrate body from the transparent carrier plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a top view of an embodiment of the display module substrate of the present invention; 
         FIG. 2  is a partial three-dimensional view of the embodiment of  FIG. 1 ; 
         FIG. 3  is a cross-sectional view of the embodiment of  FIG. 2  along the AA line; 
         FIG. 4  shows a bottom view of the embodiment of the display module substrate of the present invention; 
         FIG. 5  shows a flow chart of the manufacturing process of display module substrate of the present invention; 
         FIGS. 6-7  show schematic views of the manufacturing process of display module substrate of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As shown in  FIGS. 1-2 , the display module substrate of the present invention includes a substrate body  100  and a plurality of signal circuits  350 . The substrate body  100  has a supporting surface  150 ; the signal circuits  350  are disposed on the supporting surface  150 . On the other hand, the substrate body  100  has a bottom surface  160  opposite to the supporting surface  150 . In detail, the substrate body  100  may be a plastic material and preferably flexible. In a preferred embodiment, the substrate body  100  may be in the form of plastic thin film. Material for the substrate body can be, for example, polyimide (P1). In addition, the display module substrate  10  may be, for example, the substrate for LCD (Liquid Crystal Device) display module, the substrate of OLED (Organic Light-Emitting Diode), but not limited thereto. 
     The supporting surface  150  of the substrate body  100  includes a viewing area  200  and a signal circuit area  300 , wherein at least a portion of the signal circuit area  300  may be a fan-out area and/or an IC (integrated circuit) bonding area. IC(s) may be disposed on the fan-out area by means of such as COG (chip on glass), COF (chip on film) and others. The plurality of signal circuits  350  is disposed on the signal circuit area  300 . Preferably, the plurality of signal circuits  350  crowd together on the signal circuit area  300  and form at least a crowd. Take the embodiments shown in  FIGS. 1-2  for example; the plurality of signal circuits  350  forms five crowds on the signal circuit area  300  and the signal circuits  350  in each crowd are distributed according to a specific pattern. For example, multiple signal circuits  350  in the crowd extend and simultaneously converge toward the pads  380  to constitute a signal crowd in the shape of trapezoid-like or fan-like. 
     The signal circuit area  300  may be on one side of the viewing area  200  and usually distributed along the side of the viewing area  200 . In other embodiments, the viewing area  200  may have more than one side with the signal circuit area  300  distributed. 
     The viewing area  200  of the supporting surface  150  may further include electrodes and/or driving elements such as TFT (Thin-Film Transistor), liquid crystals, illumination material and/or color filter. The signal circuits  350  on the signal circuit area  300  may be electrically connected to the electrodes and/or driving elements; in addition, a driving circuit of the display module such as IC driver may be connected to the signal circuits  350  on the signal circuit area  300  of the substrate body  100 . 
     As shown in  FIGS. 3-4 , the signal circuit area  300  further has a plurality of apertures  360  running through the substrate body  100 . In other words, openings of the apertures  360  are on the supporting surface  150  and the bottom surface  160 , wherein depth of the apertures is preferably 5-100 micrometers and is substantially equal to the thickness of the substrate body  100 . Multiple apertures  360  which preferably have a diameter W of not less than 1 micrometer may be formed on the substrate body  100  by means of drilling approaches, such as laser cutting and punching, wherein a distance D between the adjacent apertures  360  are preferably not less than 1 micrometer (in  FIG. 3 , the distance D is shown from the left end of one aperture to the left end of the adjacent aperture; alternatively, the distance D can be shown between the centerlines of the adjacent apertures). On the other hand, the apertures  360  are not shielded by the signal circuits  350  on the signal circuit area  300 ; for example, the apertures  360  are formed between the adjacent signal circuits  350 . In the embodiment of the present invention, at least a portion of the apertures  360  are located between the adjacent signal circuits  350 . When the plurality of signal circuits  350  in the signal circuit area  300  form the crowds such as the signal crowd in the shape of fan as mentioned above, the apertures  360  located in the crowds and between the adjacent signal circuits  350  may be distributed in the shape of fan. 
     As mentioned above, the substrate body  100  has the bottom surface  160  opposite to the supporting surface  150 . Preferably, notches S are formed on the bottom surface  160 . The notches S may be resulted from high-energy light etching such as laser etching. Further, the notches S are preferably distributed on a portion of the bottom surface  160  that corresponds to the signal circuit area  300  on the opposite supporting surface  150 . The apertures  360  runs through the substrate body  100  and have openings on the supporting surface  150  and the bottom surface  160 ; the openings of the apertures  360  are further in the signal circuit area  300  of the supporting surface  150  and the portion of the bottom surface  160 , wherein the portion of the bottom surface  160  corresponds to the signal circuit area  300 , i.e. a portion of the supporting surface  150  which is just opposite to the portion of the bottom surface  160  has the signal circuit area  300 . The openings of the apertures  360  on the bottom surface  160  area are surrounded by the notches S. 
     In the preferred embodiment of the present invention, the apertures  360  and the notches S may be resulted from the formation of the display module substrate  10  or remained therefrom. Further, the apertures  360  are the structures which the display module substrate  10  needs in a releasing process, wherein the apertures  360  may serve as passages for gas exhausting. The notches S are traces resulted from the releasing process carried out by laser. The manufacturing method of the display module substrate  10  are further described as followings. 
     As the embodiment shown in  FIG. 5 , the manufacturing method of the display module substrate  10  of the present invention may include step  510  of disposing a substrate body on a transparent carrier plate, wherein the substrate body has a bottom surface and a supporting surface opposite to the bottom surface. The bottom surface is attached to the transparent carrier plate; the supporting surface includes a viewing area and a signal circuit area on one side of the viewing area. 
     Since the substrate body  100  of the display module substrate  10  is flexible and usually has poor tolerance to high temperature, a carrier plate is provided to assist in the manufacture of the display module substrate. The carrier plate preferably has transparency and may be, for example, a glass plate. Light energy may be used during a releasing process. In addition, the substrate body  100  may be directly formed on the carrier plate, such as the transparent carrier plate  400  shown in  FIG. 6 . For example, material for the substrate body  100  may be coated on the transparent carrier plate  400  to form the substrate body  100 . 
     The formed substrate body  100  has a bottom surface  160  and a face exposed outsides. As shown in  FIG. 6( b ) , the bottom surface  160  is attached to the surface of the transparent carrier plate  400 ; the face exposed outsides will be the supporting surface  150 . The supporting surface  150  is divided into several parts and at least into the viewing area  200  and the signal circuit area  300 . 
     On the other hand, the step  510  preferably further includes disposing a sacrificial layer  500  or water-resistant layer on the transparent carrier plate (please refer to  FIG. 7 ). The sacrificial layer may be formed directly on the transparent carrier plate; for example, a material such as an inorganic material for the sacrificial layer is coated on the substrate body to form the sacrificial layer. The sacrificial layer is formed between the substrate body and the transparent carrier plate; in other words, the substrate body is disposed on the sacrificial layer when the sacrificial layer is disposed on the transparent carrier plate. The sacrificial layer preferably has two opposite surfaces attached to the transparent carrier plate and the substrate body, respectively. The sacrificial layer may be an expendable to relieve loss of the substrate body during the releasing process. 
     The manufacturing method of the display module substrate  10  of the present invention further includes step  520  of disposing a plurality of signal circuits on the signal circuit area. 
     Preferably, the step  520  further includes disposing electrode(s) and/or driving element(s) on the supporting surface  150 . In the preferred embodiment of the present invention, as shown in  FIG. 6( c ) , TFT array  610  are formed on the supporting surface  150 , wherein a plurality of signal circuits of the TFT array  610  are disposed on the signal circuit area  300 . Preferably, the plurality of signal circuits  350  crowd together in the signal circuit area  300  to form at least one crowd. The plurality of signal circuits  350  in the at least one crowd are distributed specifically in shape. For example, multiple signal circuits  350  in the crowd extend and simultaneously converge toward the pads  380  to constitute a circuit crowd in the shape of trapezoid-like or fan-like. 
     In addition, the manufacturing method of the display module  10  of the present invention may further include disposing such as liquid crystals, illumination material, filter and/or film encapsulation. Take the embodiment shown in  FIG. 3  for example. In the preferred embodiment of the present invention, organic illumination material is further disposed on the supporting surface  150 , wherein an organic layer  620  is formed by such as vapor or liquid phase deposition and coating; it is preferred to from thin film encapsulation  630  outsides the organic layer  620 . The display module substrate  10  manufactured in this way may serve as substrate for OLED. 
     The manufacturing method of the display module substrate  10  of the present invention further includes step  530  of forming a plurality of apertures in the signal circuit area, wherein the apertures run through the substrate body and are not shielded by the signal circuits. When the sacrificial layer is disposed between the substrate body and the transparent carrier plate, the apertures may further run through the sacrificial layer. Multiple apertures  360  which preferably have a diameter W of not less than 1 micrometer may be formed on the substrate body  100  by means of drilling approaches such as laser cutting and punching, wherein a distance D between the adjacent apertures  360  are preferably not less than 1 micrometer. Take the embodiment shown in  FIG. 6  for example; the drilling starts from the side of the substrate body  100  opposite to the transparent carrier plate  400 , i.e. the supporting surface  150 . Further, the drilling is carried out in the signal circuit area  300  of the supporting surface  150  (alternatively, the drilling may be carried out from a bottom face of the glass plate) and keeps away from the signal circuits  350 . The drilling preferably acts on an interface of the transparent carrier plate  400  and the substrate body  100  so as to ensure the formation of the apertures  360  running through the substrate body  100 . The apertures  360  may be located at space between the adjacent signal circuits  350 . When the plurality of signal circuits  350  crowd together in the signal circuit area  300  such as crowd together to form the signal crowd in the shape of fan-like, the apertures distributed therein may accordingly constitute the shape of fan. 
     The manufacturing method of the display module substrate  10  of the present invention further includes step  540  of etching the bottom surface by high-energy light through the transparent carrier plate to separate the substrate body from the transparent carrier plate. The step  540  is also called the releasing process. In the preferred embodiment of the present invention, the high-energy light may be laser such as UV laser. Please refer to both  FIGS. 6( e )  and  7 ; high-energy light E may be emitted from one side of the transparent carrier plate  400  that is opposite to the substrate body  100  and through the transparent carrier plate  400 . Energy of the high-energy light is sufficient to pass through the transparent carrier plate  400 , wherein the high-energy light preferably arrives at the interface of the transparent carrier plate and the substrate body  100 . 
     Further speaking, the high-energy light E may penetrate at least a portion of the transparent carrier plate  400 , wherein a portion of the substrate body  100  supported by the portion of the transparent carrier plate  400  has the signal circuit area  300  on the opposite supporting surface  150 . Accordingly, the high-energy light E may penetrate the transparent carrier plate  400  and arrive at a portion of the bottom surface  160 , wherein the portion of the bottom surface  160  corresponds to the signal circuit area  300  of the supporting surface  150  on opposite side. The high-energy light E may decompose or damage the bottom surface  160  by which the substrate body  100  is attached to the transparent carrier plate  400  and release the attachment of the substrate body  100  and the transparent carrier plate  400 , which results in separation of the substrate body  100  and the transparent carrier plate  400 . The process is usually accompanied by generation of heat and gas P. In addition, the high energy may also result in notches due to a scanning path. 
     The gas P may come from the decomposition and/or vaporization of the substrate body  10 , wherein the molecules of gas P may be the molecules of carbon group. The gas P first appears between the substrate body  100  and the transparent carrier plate  400  and is able to escape and leave away from a space A between the substrate body  100  and the transparent carrier plate  400 . Accordingly, it is not easy for the substrate body  100 , especially the portion of the substrate body  100  having the signal circuit area  300  to deform due to synergy effect resulted from the gas P and gas in the small space A. Specifically, the deformation may be an expansion of the substrate body  100  resulted from pressure and heat coming from the direction of the transparent carrier plate  400 . 
     On the other hand, when the sacrificial layer is disposed between the substrate and the transparent carrier plate, the high-energy light E may be emitted from a side of the transparent carrier plate  400  opposite to the sacrificial layer  500 . The energy of the high-energy light is sufficient to pass through the transparent carrier plate  400 , wherein the high-energy light preferably arrives at an interface of the transparent carrier plate  400  and the sacrificial layer  500 . The high energy light E may decompose or damage the sacrificial layer  500  to release the attachment of the substrate body  100  and the transparent carrier plate  400  and separate the substrate body  100  and the transparent carrier plate  400  from each other. In addition, loss of the substrate body  100  in the releasing process is therefore reduced by the deposition of the sacrificial layer  500 . 
     In comparison to variation of the pitch between the pads of the conventional signal circuit area due to deformed substrate body, the apertures  360  of the substrate body  100  can reduce the variation. Because of the releasing process of the present invention, improvement in the substrate body  100  and the element thereon further improves the subsequent processes and therefore increase the yield of the display module substrate. 
     On the other hand, in the preferred embodiment of the present invention, the high-energy light E may be emitted into the transparent carrier plate  400  in the extension direction of the signal circuit area  300  (i.e. the longer side) that accordingly separates a portion of the substrate body  100  along the extension direction from the transparent carrier plate  400 . In addition, the laser may substantially scan the plate in accordance with the width direction of the signal circuit area  300 . Following the laser&#39;s moving, as shown in  FIG. 7 , portions of the substrate body  100  in the width direction of the signal circuit area  300  substantially separate from the transparent carrier plate. 
     As shown in  FIG. 4 , the notches S resulted from the etching of the bottom surface  160  by the high-energy light surround the apertures  360 , wherein a portion of the bottom surface  160  having the notches S reflects where the high-energy light E acts on. That is, the high-energy light acts in the vicinity of the apertures  360  and a portion of the substrate body around the apertures  360 ; accordingly, molecules of gas P resulted from vaporization of the portion of the substrate body  10  may escape through the apertures  360 . 
     As shown in  FIG. 6( f ) , after the step  540 , the substrate body  100  is easily separated from the transparent carrier plate  400  to accomplish the manufacture of the display module substrate  10 . Alternatively, after the step  540 , a driving circuit can be disposed on the substrate body  100 /display module substrate  10 . 
     Although the preferred embodiments of present invention have been described herein, the above description is merely illustrative. The preferred embodiments disclosed will not limit the scope of the present invention. Further modification of the invention herein disclosed will occur to those skilled in the respective arts and all such modifications are deemed to be within the scope of the invention as defined by the appended claims.