Patent Publication Number: US-2017358520-A1

Title: Chip-on-film package and display device including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2016-0072653, filed in the Korean Intellectual Property Office on Jun. 10, 2016, the disclosure of which is incorporated by reference herein in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to a chip-on-film (COF) package, and more particularly, to a COF package and a display device including the COF package. 
     DISCUSSION OF THE RELATED ART 
     A display device may be used to display an image. A display device may use a liquid crystal display, an organic light-emitting diode display, or the like, to display the image. Display devices that can be bent or folded are being developed. 
     A bendable or foldable display device includes a display panel, the display panel including a plurality of pixels, and a driver supplying signals to the plurality of pixels. The display panel may include a plurality of gate lines and a plurality of data lines. Each pixel is connected to a gate line and a data line to receive signals. The gate lines transmit gate signals from a gate driver, and the data lines transmit data signals from a data driver. 
     The gate and data drivers may be embodied as integrated circuit (IC) chips, and the IC chips may be mounted on a film to create a chip-on-film (COF) package. In a process of attaching the IC chips to the film, the film may be bent and/or deformed without damage. 
     SUMMARY 
     According to an exemplary embodiment of the present invention, a chip-on-film (COF) package includes a film, a driver integrated circuit (IC) chip disposed on the film, an electrode pad disposed on an edge of the film, and a first deformation-preventing member disposed on the film, between the driver IC chip and the electrode pad. 
     According to an exemplary embodiment of the present invention, a COF package includes a film including a first low-elasticity region, a second low-elasticity region, and a high-elasticity region disposed between the first low-elasticity region and the second low-elasticity region, a driver IC chip disposed on the first low-elasticity region of the film, and an electrode pad disposed on the second low-elasticity region of the film. The high-elasticity region has a higher elastic coefficient than the first low-elasticity region and the second low-elasticity region. 
     According to an exemplary embodiment of the present invention, a display device includes a display panel, and a COF package connected to an edge of the display panel. The COF package includes a film, driver IC chip disposed on the film, an electrode pad disposed on an edge of the film, and a first deformation-preventing member disposed on the film, between the driver IC chip and the electrode pad. 
     According to an exemplary embodiment of the present invention, a COF package includes a film, a driver IC chip mounted on the film, an electrode pad disposed on an edge of the film, and a deformation-preventing member disposed on the film, between the driver IC chip and the electrode pad. The deformation-preventing member is a stiffener that reduces bending or warping of the film. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features of the present invention will become more apparent by describing in detail exemplary embodiments thereof in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a top plan view illustrating a display device according to an exemplary embodiment of the present invention; 
         FIG. 2  is a top plan view illustrating a chip-on-film (COF) package of a display device according to an exemplary embodiment of the present invention; 
         FIG. 3  is a cross-sectional view taken along line of  FIG. 2 ; 
         FIG. 4  is a top plan view illustrating a COF package of a display device according to an exemplary embodiment of the present invention; 
         FIG. 5  is a top plan view illustrating a COF package of a display device according to an exemplary embodiment of the present invention; 
         FIG. 6  is a top plan view illustrating a COF package of a display device according to an exemplary embodiment of the present invention; 
         FIG. 7  is a cross-sectional view illustrating a COF package of a display device according to an exemplary embodiment of the present invention; 
         FIG. 8  is a cross-sectional view illustrating a COF package of a display device according to an exemplary embodiment of the present invention; 
         FIG. 9  is a top plan view illustrating a COF package of a display device according to an exemplary embodiment of the present invention; 
         FIG. 10  is a top plan view illustrating a COF package of a display device according to an exemplary embodiment of the present invention; and 
         FIG. 11  is a cross-sectional view illustrating a COF package of a display device according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, the present invention will be described more fully with reference to the accompanying drawings. The described embodiments may be modified in different ways without departing from the spirit and scope of the present invention. 
     Like reference numerals may refer to like elements throughout the specification. The layers and/or elements in the drawings may be exaggerated for clarity. 
     When a layer or element is referred to as being on another layer or element, the layer or element may be directly disposed on the other layer or element, or intervening layers or elements may be present therebetween. 
       FIG. 1  is a top plan view illustrating a display device according to an exemplary embodiment of the present invention. 
     As shown in  FIG. 1 , a display device includes a display panel  100 , a chip-on-film (COF) package  400  attached to an edge of the display panel  100 , and a printed circuit board (PCB)  500  attached to an edge of the COF package  400 . 
     The display panel  100  may be a liquid crystal panel, an organic light-emitting diode panel, or the like. The display panel  100  includes a display area DA and a non-display area NDA. The non-display area NDA may be disposed at an edge or border of the display panel  100 . In  FIG. 1 , the non-display area NDA has a shape which frames the display area DA. For example, the non-display area NDA has a rectangular shape which is disposed along the entire border of the display area DA. However, the present invention is not limited to this particular shape or configuration of the non-display area NDA. For example, the non-display area NDA may be disposed on one or two edges of the display area DA. 
     A plurality of pixels may be disposed in the display area DA of the display panel  100 . The plurality of pixels may be arranged in a matrix shape. The plurality of pixels may be connected to gate lines and data lines of the display device. Accordingly, the plurality of pixels may receive signals through the gate lines and data lines. 
     A COF package  400  may be attached to the non-display area DA of the display panel  100 . In  FIG. 1 , the COF package  400  is attached to the lower edge of the display panel  100 . However, the present invention is not limited thereto, and the COF package  400  may be attached to other edges of the display panel  100 . 
     A driver integrated circuit (IC) chip  450  may be attached to the COF package  400 . The driver IC chip  450  may transmit the signals to the display area DA of the display panel  100  to drive the plurality of pixels. The driver IC chip  450  may include a data driver. The data driver may generate data signals to be transmitted to the data lines. In addition, the driver IC chip  450  may include a gate driver. The gate driver may generate gate signals to be transmitted to the gate lines. However, the gate driver may also be formed as an amorphous silicon gate (ASG), and the ASG may be disposed in the non-display area DA of the display panel  100 . 
     The PCB  500  may generate a plurality of signals for driving the plurality of pixels in the display area DA of the display panel  100 . For example, a timing controller may be disposed in the PCB  500 , and the timing controller may generate a driving signal for driving the plurality of pixels. The PCB  500  is connected to the COF package  400 . 
       FIG. 2  is a top plan view illustrating a COF package of a display device according to an exemplary embodiment of the present invention.  FIG. 3  is a cross-sectional view taken along line of  FIG. 2 . 
     The COF package  400  of a display device may include a film  410 , a driver IC chip  450  and an output electrode pad  423  disposed on the film  410 , and a deformation-preventing member  430  disposed between the driver IC chip  450  and the output electrode pad  423 . The film  410  may include a plurality of output electrode pads  423 . The deformation-preventing member  430  may be used as a stiffener that reduces deformation, bending or warping of the film  410 . 
     The film  410  may include a thin material that might not be easily bent. 
     The driver IC chip  450  may be disposed on a central region of the film  410 . The driver IC chip  450  may have a rectangular shape that is elongated in a horizontal (e.g., first) direction. 
     The output electrode pad  423  may be disposed on an edge of the film  410 . For example, the output electrode pad  423  may be disposed on an upper edge of an upper surface of the film  410 , as shown in  FIG. 3 . The output electrode pad  423  may overlap the non-display area NDA of the display panel  100  and may be connected to a pad of the display panel. An anisotropic conductive film (ACF) may be disposed between the output electrode pad  423  and the display panel  100 . The anisotropic conductive film may conduct electricity only along a thickness direction of the film  410  (e.g., between the film  410  and the output electrode pad  423 ). The anisotropic conductive film may electrically connect the output electrode pad  423  with the pad of the display panel  100 . 
     The deformation-preventing member  430  may be disposed on the film  410 , for example, between the driver IC chip  450  and the output electrode pad  423 . The deformation-preventing member  430  may have a bar shape. The deformation-preventing member  430  may extend in a direction parallel to the driver IC chip  450 . For example, the deformation-preventing member  430  may have a bar shape that is elongated in the horizontal (e.g., first) direction. A thickness of the deformation-preventing member  430  may be in a range of about 0.1 mm to about 5 mm. A width of the deformation-preventing member  430  may be in a range of about 0.1 mm to about 5 mm. For example, in an exemplary embodiment of the present invention, the width and the thickness of the deformation-preventing member may be about 1 mm each. 
     The deformation-preventing member  430  includes a hardener. The deformation-preventing member  430  may be formed by coating the hardener, in a liquid form, on the film  410  by using a dispenser and hardening the liquid hardener. After forming the deformation-preventing member  430  on the film  410 , the driver IC chip  450  may be attached to the film  410 . The process of attaching the driver IC chip  450  to the film  410  may be performed at a high temperature and a high pressure such that the film  410  may be deformed, bent or warped. In an exemplary embodiment of the present invention, the deformation-preventing member  430  is disposed between the driver IC chip  450  and the output electrode pad  423  to increase the strength of the film  410 . Accordingly, when attaching the driver IC chip  450  to the film at a high temperature and a high pressure, the deformation-preventing member  430  may prevent the film  410  from becoming deformed, bent or warped. 
     The hardener may include an ultraviolet (UV) hardener, a room temperature hardener, or the like. When using a UV hardener, the UV hardener is hardened by being exposed to ultraviolet rays, and the room temperature hardener is hardened after a predetermined waiting time at room temperature. The room temperature hardener may be, for example, SE4900, SE9168, or SE9186 of the DOW CORNING CORPORATION, or DP100 or DP420 of the 3M CORPORATION. The UV hardener may be, for example, A700 or A785 of the SEKISUI CORPORATION, or HC-601Z, HC-602S, or HC-603Z of the HANSOL CHEMICAL CORPORATION. 
     Next, a change in a bending amount of a film  410  before and after attaching a driver IC chip  450  to a COF package  400  will be described with reference to Table 1. The bending amount will be shown for a film  410  including a deformation-preventing member  430 , and for a film  410  that does not include a deformation-preventing member  430 . 
     The bending amount of the film  410  is used to measure a change in the thickness of the film  410  with reference to a flat state of the film  410 . 
     
       
         
           
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Bending amount of film 410 after 
               
               
                   
                 attachment of a driver IC chip 450 
               
            
           
           
               
               
               
               
            
               
                   
                 Pre-existing bending 
                 Case without a 
                 Case with a 
               
               
                   
                 amount of film 410 
                 deformation- 
                 deformation- 
               
               
                   
                 before attachment of a 
                 preventing 
                 preventing 
               
               
                   
                 driver IC chip 450 
                 member 430 
                 member 430 
               
               
                   
                 (μm) 
                 (μm) 
                 (μm) 
               
               
                   
                   
               
            
           
           
               
               
               
               
            
               
                 Case #1 
                 9.1 
                 22.8 
                 11 
               
               
                 Case #2 
                 11.4 
                 20.0 
                 8.1 
               
               
                 Case #3 
                 5.5 
                 21.0 
                 22.1 
               
               
                   
               
            
           
         
       
     
     Referring to Table 1, the film  410  has a bending amount of about 5 μm to about 11 μm before the attachment of the driver IC chip  450 . When the driver IC chip  450  is attached to the COF package  400  without the deformation-preventing member  430 , the film  410  has a bending amount of about 20 μm to about 23 μm. Accordingly, the bending amount of the film  410  increases in the process of attaching the driver IC chip  450 . 
     The deformation of the film  410  is reduced in the case of the COF package  400  formed with the deformation-preventing member  430 , when compared with the COP package  400  that excludes the deformation-preventing member  430 . Case #1 uses HC-601Z as the deformation-preventing member  430 , Case #2 uses HC-602S as the deformation-preventing member  430 , and Case #3 uses SE9168 as the deformation-preventing member  430 . As can be seen in Table 1, the prevention of the deformation of the film  410  is large when using HC-601Z and HC-602S. 
     The COF package  400  may further include an input electrode pad  421 . The input electrode pad  421  may be disposed on an edge of the film  410 . The film  410  may include a plurality of input electrode pads  421 . The input electrode pad  421  may be disposed on an edge of the film  410  opposite to the edge where the output electrode pad  423  is disposed. For example, the input electrode pad  421  may be disposed on a lower edge of the film  410 . The input electrode pad  421  is connected to the PCB  500 . The anisotropic conductive film may also be disposed between the input electrode pad  421  and the PCB  500 . 
       FIG. 4  is a top plan view illustrating a COF package of a display device according to an exemplary embodiment of the present invention. 
     The COF package  400  of  FIG. 4  may include a plurality of deformation-preventing members  430 . 
     Referring to  FIG. 4 , the COF package  400  includes the film  410 , the driver IC chip  450  and the output electrode pad  423  disposed on the film  410 , and a plurality of deformation-preventing members  430  disposed between the driver IC chip  450  and the output electrode pad  423 . 
     Two deformation-preventing members  430  may be disposed between the driver IC chip  450  and the output electrode pad  423 . The two deformation-preventing members  430  may each have a bar shape and may extend parallel to each other. The two deformation-preventing members  430  may each extend in a direction parallel to the driver IC chip  450 . 
       FIG. 5  is a top plan view illustrating a COF package of a display device according to an exemplary embodiment of the present invention.  FIG. 6  is a top plan view illustrating a COF package of a display device according to an exemplary embodiment of the present invention. 
     In  FIG. 4 , two deformation-preventing members  430  are disposed between the driver IC chip  450  and the output electrode pad  423 . However, the present invention is not limited thereto. For example, two or more deformation-preventing members  430  may be disposed between the driver IC chip  450  and the output electrode pad  423 . As shown in  FIG. 5 , three deformation-preventing members  430  may be disposed between the driver IC chip  450  and the output electrode pad  423 . Furthermore, four or more deformation preventing members  430  may be positioned between the driver IC chip  450  and the output electrode pad unit  423 . 
     In  FIG. 2 ,  FIG. 4 , and  FIG. 5 , each deformation-preventing member  430  has a length corresponding to the width of the film  410  at the location where the deformation-preventing member  430  is formed. However the present invention is not limited thereto. For example, as shown in  FIG. 6 , a plurality of deformation-preventing members  430 , each having a shorter length than the width of the film  410 , may be disposed to extend along a same direction (e.g., along a first direction) and may be separated from each other by a predetermined distance along the first direction. In the exemplary embodiments of  FIG. 2 ,  FIG. 4 , and  FIG. 5 , the liquid hardener may be coated in a solid line shape to form the deformation-preventing member  430 , while in the exemplary embodiment of  FIG. 6 , the liquid hardener is coated in a dotted line shape to form the deformation-preventing member  430 . For example, in the exemplary embodiment of  FIG. 6 , a process of alternately discharging and stopping the discharging process of the liquid hardener at predetermined times, while moving the dispenser, may be repeatedly performed. 
     In  FIG. 6 , the deformation-preventing members  430  are disposed along two parallel imaginary lines. However, a distance by which the imaginary lines are separated from each other may vary. For example, the two imaginary lines may cross each other. Accordingly, the two deformation-preventing members  430  may cross each other. 
     In  FIG. 6 , the deformation-preventing members  430  have a dotted line shape and are substantially parallel to each other. However, the present invention is not limited thereto. For example, one or more deformation-preventing members  430  may be disposed on the film  410 , and each of the one or more deformation-preventing members  430  may have a dotted line shape. Further, when there are two or more deformation-preventing members  430 , the deformation-preventing members  430  may cross each other or may be parallel to each other, regardless of whether the two or more deformation-preventing members  430  have a continuous line shape or a dotted line shape. 
       FIG. 7  is a cross-sectional view illustrating a COF package of a display device according to an exemplary embodiment of the present invention. 
     In the COF package  400  of  FIG. 7 , the deformation-preventing member may be disposed on the lower surface of the film  410 . 
     The COF package  400  of  FIG. 7  includes the deformation-preventing member  430  disposed between the driver IC chip  450  and the output electrode pad  423 . In  FIG. 7 , the deformation-preventing member  430  is disposed on a first surface of the film  410 , the first surface of the film  450  being opposite to a second surface of the film  410 . The driver IC chip  450  and the output electrode pad  423  are disposed on the second surface of the film  450 . The first surface of the film  410  may also be referred to as a lower surface of the film  410 . The second surface of the film  410  may also be referred to as an upper surface of the film  410 . 
       FIG. 8  is a cross-sectional view illustrating a COF package of a display device according to an exemplary embodiment of the present invention. 
     The COF package  400  of  FIG. 8  may include a deformation-preventing member  430  on each of the first and second surface of the film  410 . For example, the COF package  400  of  FIG. 8  may include a deformation-preventing member  430  on both the lower and upper surfaces of the film  410 . 
     The COF package  400  of  FIG. 8  includes the deformation-preventing member  430  disposed between the driver IC chip  450  and the output electrode pad  423 . In the COF package  400  of  FIG. 8 , a deformation-preventing member  430  is disposed on the lower surface of the film  410 , and a deformation-preventing member  430  is disposed on the upper surface of the film  410 . For example, as shown in  FIG. 8 , the driver IC chip  450  and the output electrode pad  423  are disposed on the upper surface of the film  410 , and the deformation-preventing members  430  may respectively overlap the upper surface and the lower surface of the film  410 . In this case, the deformation-preventing members  430  may also overlap each other. 
       FIG. 9  is a top plan view illustrating a COF package of a display device according to an exemplary embodiment of the present invention. 
     The COF package  400  of  FIG. 9  includes a deformation-preventing member  430  disposed between the driver IC chip  450 , and the input electrode pad  421 . 
     The COF package  400  of  FIG. 9  includes the film  410 , the driver IC chip  450 , the output electrode pad  423 , and the input electrode pad  421  disposed on the film  410 , and the deformation-preventing member  430  disposed between the driver IC chip  450  and the input electrode pad  421 . 
     In  FIG. 9 , the deformation-preventing member  430  is disposed between the driver IC chip  450  and the input electrode pad  421 . 
       FIG. 10  is a top plan view illustrating a COF package of a display device according to an exemplary embodiment of the present invention. 
     The COF package  400  of  FIG. 10  includes a first deformation-preventing member  430 , which is disposed between the driver IC chip  450  and the input electrode pad  421 , and a second deformation-preventing member  430 , which is disposed between the driver IC chip  450  and the output electrode pad  423 . 
     The COF package  400  of  FIG. 10  includes the film  410 , the driver IC chip  450 , the output electrode pad  423 , the input electrode pad  421  disposed on the film  410 , a first deformation-preventing member  430  disposed between the driver IC chip  450  and the output electrode pad  423  and a second deformation-preventing member  430  disposed between the driver IC chip  450  and the input electrode pad  421 . 
     Accordingly, in the exemplary embodiment of the present invention described with reference to  FIG. 10 , a deformation-preventing member  430  is disposed on both sides of the driver IC chip  450 . The deformation-preventing members  430  of  FIG. 10  may extend along the extending direction of the driver IC chip  450 . 
       FIG. 11  is a cross-sectional view illustrating a COF package of a display device according to an exemplary embodiment of the present invention. 
     The COF package  400  of  FIG. 11  may include a film  410 . Different regions of the film  410  may include different materials. 
     The COF package  400  of  FIG. 11  includes the film  410 , and the driver IC chip  450  and the output electrode pad  423  disposed on the film  410 . In this case, the deformation-preventing member  430  might not be separately formed. 
     The film  410  includes a first low-elasticity region  414 , a second low-elasticity region  416 , and a high-elasticity region  412 . The high-elasticity region  412  has a higher elastic coefficient than that of the first low-elasticity region  414  and the second low-elasticity region  416 . For example, the high-elasticity region  412  may be more flexible or more elastic than the first or second low-elasticity regions  414  and  416 . The high-elasticity region  412  may be disposed between the first low-elasticity region  414  and the second low-elasticity region  416 . 
     The driver IC chip  450  may be disposed on the first low-elasticity region  414  of the film  410 , and the output electrode pad  423  may be disposed on the second low-elasticity region  416  of the film  410 . Accordingly, the high-elasticity region  412  may be disposed between the driver IC chip  450  and the output electrode pad  423 . In an exemplary embodiment of the present invention, the high-elasticity region  412  on the film  410  serves the same function as the deformation-preventing member  430 . The strength of the film  410  may be partially increased by the high-elasticity region  412  of the film  410 . Accordingly, when exposing the film  410  to a high temperature and a high pressure to attach the driver IC chip  450  thereto, the film  410  may be deformed, bent, or warped by a small degree. For example, the deformation, bending or warping of the film  410  at a high temperature and high pressure, when attaching the driver IC chip  450  thereto, may be reduced when including the high-elasticity region  412  between the first and second low-elasticity regions  414  and  416 , or when including the deformation-preventing members  430  on the film  410 . 
     While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be apparent to those of ordinary skill in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present invention.