Abstract:
A bonding apparatus for a display device includes a film bonding device configured to attach an anisotropic conductive film to a panel, and a pressure device configured to bond a driving chip and a flexible printed circuit to the panel. The pressure device includes a pressure head including a heat source, a pressure tip attached to a bottom side of the pressure head and the pressure tip being configured to press the flexible printed circuit to the panel, and a transfer unit attached to an upper side of the pressure head, the transfer unit being configured to transfer the pressure head. The heat source is located in the pressure head.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2012-0050944 filed in the Korean Intellectual Property Office on May 14, 2012, the entire contents of which are incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     Embodiments relate to a bonding apparatus for a display device and a method thereof. 
     2. Description of Related Art 
     In a film on glass (FOG) bonding process for module manufacturing of, for example, an organic light emitting diode (OLED) display, a liquid crystal display (LCD), and the like, a flexible printed circuit (FPC) is aligned with a panel to which an anisotropic conductive film (ACF) is attached. Then, a sheet is covered for heat dissipation and protection on an upper side of the FPC, and a location to be connected is pressed using a heat-applied pressure tip of a bonding apparatus for a display device for electric connection between the panel and an electrode of the FPC. 
     SUMMARY 
     Embodiments are directed to a bonding apparatus for a display device, including a film bonding device configured to attach an anisotropic conductive film to a panel, and a pressure device configured to bond a driving chip and a flexible printed circuit to the panel. The pressure device includes a pressure head including a heat source, a pressure tip attached to a bottom side of the pressure head and the pressure tip being configured to press the flexible printed circuit to the panel, and a transfer unit attached to an upper side of the pressure head, the transfer unit being configured to transfer the pressure head. The heat source is located in the pressure head. 
     The pressure head may be disposed at a position biased toward one side of the transfer unit with reference to a center axis of the transfer unit. The pressure head may overlap the pressure tip. 
     The bonding apparatus may further include a tip fixing member fixing the pressure tip to the pressure head. The tip fixing member may simultaneously contact a bottom side of the pressure head and a side of the pressure tip. 
     The bonding apparatus may further include an auxiliary pressure head extended in a horizontal direction from the pressure head and attached to the transfer unit. An auxiliary heat source is provided in the auxiliary pressure head. A bottom side of the auxiliary pressure head may be disposed higher than a bottom side of the pressure head. The auxiliary heat source may be disposed higher than the heat source. 
     Embodiments are also directed to a film pressure method using a bonding apparatus for a display device. The method includes bonding a driving chip to a chip on glass bonding portion of a panel, positioning a flexible printed circuit on a film on glass bonding portion of the panel, and bonding the flexible printed circuit to the film on glass bonding portion of the panel using a pressure tip of the bonding apparatus for the display device. In the bonding of the flexible printed circuit, a heat source of a pressure head connected to the pressure tip of the bonding apparatus for the display device may be in a non-overlapping relationship with the chip on glass bonding portion. The heat source of the pressure head may be in a non-overlapping relationship with a film on glass bonding portion. 
     The pressure head of the bonding apparatus for the display device may be disposed at a position biased toward one side of the transfer unit with reference to a center axis of a transfer unit. The bonding apparatus may further include an auxiliary pressure head extended in a horizontal direction from the pressure head and having an auxiliary heat source provided therein. The auxiliary heat source may be disposed higher than the heat source. 
     The pressure tip may not overlap the chip on glass bonding portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features will be come apparent to those of skill in the art by describing in detail exemplary embodiments with reference to the attached drawings in which: 
         FIG. 1  is a schematic diagram of an entire bonding apparatus for a display device according to an exemplary embodiment. 
         FIG. 2  is an enlarged side view of a pressure of the bonding apparatus for the display device according to the exemplary embodiment. 
         FIG. 3  is a side view of a bonding method using the bonding apparatus for the display device according to the exemplary embodiment. 
         FIG. 4  is an enlarged side view of a pressure of a bonding apparatus for a display device according to another exemplary embodiment. 
         FIG. 5  is a side view of a bonding method using the bonding apparatus for the display device according to the exemplary embodiment of  FIG. 4 . 
         FIG. 6  is an enlarged side view of a pressure of a bonding apparatus for a display device according to another exemplary embodiment. 
         FIG. 7  is a side view of a bonding method using the bonding apparatus for the display device according to the exemplary embodiment of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments 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 thereof. 
     Like reference numerals refer to like elements throughout the specification. The size and thickness of each component shown in the drawings are arbitrarily shown for better understanding and ease of description, and thus the embodiments not limited to those shown in the drawings. 
     Throughout the specification, it will be understood that when an element such as a layer, film, region, area or panel is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. 
       FIG. 1  is a schematic diagram of a bonding apparatus for a display device according to an exemplary embodiment.  FIG. 2  is an enlarged side view of a pressure device of the bonding apparatus for the display device according to the exemplary embodiment.  FIG. 3  is a side view of a bonding method using the bonding apparatus for the display device according to the exemplary embodiment. 
     As shown in  FIG. 1 , a bonding apparatus for a display device according to the exemplary embodiment includes a film bonding device  10  attaching an anisotropic conductive film  4  to a panel  1  and a pressure device  20  bonding a driving chip  2  and a FPC  3  to the panel  1 . (The panel  1 , driving chip  2 , FPC, and conductive film  4  are shown in  FIG. 3 .) In addition, the bonding apparatus further includes a film attachment tester  30  testing whether the anisotropic conductive film  4  is attached to the panel  1 , an anisotropic conductive film loader  40  loading the anisotropic conductive film  4 , and a bonding tester  50  testing whether a driving chip  2  and the FPC  3  are bonded to the panel  1 . The pressure device  20  may include a provisional pressure device  21  performing a provisional pressure process and a main pressure device  22  performing a main pressure process. In the description below, the term “pressure device  20 ” may refer to either the provisional pressure device  21  or the main pressure device  22 . Herein, the terms such as “upper” and “top” refer to a relative positioning farther away from a panel  1  to which a driving chip  2 , FPC  3 , and anisotropic conductive film  4  are attached, and terms such as “lower” and “bottom” refer to a relative positioning closer to the panel  1 , particularly with reference to the center axis Y. Terms such as “horizontal” refer to a direction parallel to the panel  1 , or, for example, in a direction perpendicular to the center axis Y. 
     As shown in  FIG. 2 , the pressure device  20  includes a pressure head  100  having a heat source  110  provided therein, a pressure tip  200  attached to a bottom side of the pressure head  100  and pressing the FPC  3  to the panel  1 , and a transfer unit  300  attached to an upper side of the pressure head  100  and transferring the pressure head  100 . 
     The heat source  110  of the pressure head  100  may be a heating coil. Heat generated from the heat source  110  is applied to the anisotropic conductive film  4  such that a film on glass bonding portion  1   b  of the panel  1  and the FPC  3  can be easily bonded with each other through the anisotropic conductive film  4 . 
     The pressure head  100  is disposed at a position biased toward one side of the transfer unit  300  with reference to the center axis Y of the transfer unit  300 .  FIG. 2  illustrates that one end portion of the pressure head  100  matches the center axis Y of the transfer unit  300 , but other configurations are possible. 
     The pressure head  100  overlaps the pressure tip  200 . The heat source  110  provided in the pressure head  100  is disposed in an upper portion of the pressure head  100 . Thus, during a film on glass bonding process, the chip on glass bonding portion  1   a  of the panel  1  is not disposed under the heat source  110 , and heat generated from the heat source  110  is hardly transmitted to the chip on glass bonding portion  1   a  of the panel  1 . Accordingly, the chip on glass bonding portion  1   a  may be prevented from being lifted. 
     In addition, the heat source  110  is disposed at a position biased toward one side of the transfer unit  300  with reference to the center axis Y of the transfer unit  300 . Thus, the heat source  110  does not overlap the pressure tip  200 , and therefore the film on glass bonding portion  1   b  of the panel  1  is not disposed under the heat source  110  during the film on glass bonding process. Accordingly, the heat source  110  can be prevented from influencing the film on glass bonding portion  1   b.    
     Such a pressure head  100  is attached to the transfer unit  300  using a connection member  120 . A tip fixing member  130  is further provided to fix the pressure tip  200  to the pressure head  100 . The tip fixing member  130  simultaneously contacts a bottom side of the pressure head  100  and a side of the pressure tip  200  and fixes the tip fixing member  130  to the pressure tip  200  using a tip connection member  131 . The tip fixing member  130  may be formed of the same material protruded from the pressure head  100 , or may be formed of a member separated from the pressure head  100 . 
     A bonding method using such a bonding apparatus for the display device according to the first exemplary embodiment will be described in further detail with reference to  FIG. 3 . 
     First, the driving chip  2  is bonded to the chip on glass bonding portion  1   a  of the panel  1 . In this case, the film bonding device  10  and the pressure device  20  of the bonding apparatus for the display device according to the exemplary embodiment of  FIGS. 1 and 2  are used. 
     Next, the FPC  3  is disposed in the film on glass bonding portion  1   b  of the panel  1 . The anisotropic conductive film  4  is attached to the chip on glass bonding portion  1   a  and the film on glass bonding portion  1   b  of the panel  1 , and the anisotropic conductive film  4  is formed of a double-sided adhesive tape formed by mixing a polymer cured by heat and fine conductive particles in a dispersed manner. Thus, when pressure is applied from upper and lower portions of the anisotropic conductive film  4 , the conductive particles are exploded, and thus, the polymer in the particles is wholly filled in the double-sided adhesive tape, thereby achieving conductivity and adherence. The conductive particles may include carbon fiber, or a metal such as nickel (Ni), platinum (Pt), or the like or an alloy thereof. The polymer may include styrene butadiene rubber), polyvinyl, butylene, epoxy resin, polyurethane, or acrylic resin. 
     Next, the FPC  3  is bonded to the film on glass bonding portion  1   b  of the panel  1  using the pressure tip  200  of the bonding apparatus for the display device according to the exemplary embodiment. In this case, the heat source  110  of the pressure head  100 , connected to the pressure tip  200  of the bonding apparatus for the display device according to the exemplary embodiment does not overlap the film on glass bonding portion  1   b , and the heat source  110  of the pressure head  100  does not overlap the chip on glass bonding portion  1   a.    
     Accordingly, during the film on glass bonding process, the heat generated from the heat source  110  is hardly transmitted to the chip on glass bonding portion  1   a  of the panel  1  because the chip on glass bonding portion  1   a  of the panel  1  is not located under the heat source  110 . Accordingly, the chip on glass bonding portion  1   a  may be prevented from being lifted. 
     In addition, during the film on glass bonding process, the pressure tip  200  is located so as to not overlap with the chip on glass bonding portion  1   a . Thus, during the film on glass bonding process, the chip on glass bonding portion  1   a  of the panel  1  is not located under the pressure tip  200  to which the heat from the heat source  110  is transmitted. Thus heat of the pressure tip  200  is hardly transmitted to the chip on glass bonding portion  1   a  of the panel  1 , thereby preventing the chip on glass bonding portion  1   a  from being lifted. 
     Meanwhile, only the pressure head is disposed at a position biased toward a lower portion of the transfer unit in this exemplary embodiment. An auxiliary pressure head that does not include a heat source may be further provided in the pressure head according to another exemplary embodiment. 
     Hereinafter, an exemplary embodiment will be described in further detail with reference to  FIG. 4 . 
       FIG. 4  is an enlarged side view of a pressure device  20  of a bonding apparatus for a display device according to this exemplary embodiment 
     The second exemplary embodiment shown in  FIG. 4  is substantially equivalent to the first exemplary embodiment shown in  FIG. 1  and  FIG. 2 , except that an auxiliary pressure head is further included, and therefore the iterative description will not be repeated. 
     As shown in  FIG. 4 , the bonding apparatus for the display device according to the exemplary embodiment further includes an auxiliary pressure head  400  extended in a horizontal direction from a pressure head  100  and attached to a transfer unit  300 . 
     The auxiliary pressure head  400  provides center of mass biased by the pressure head  100  so that the pressure head  100  can be further stably fixed to the transfer unit  300 . In such an auxiliary pressure head  400 , an auxiliary connection member  420  is provided to fix the auxiliary pressure head  400  to the transfer unit  300 . 
     No additional heat source  110  is provided in the auxiliary pressure head  400 . Accordingly, a chip on glass bonding portion  1   a  of a panel  1  is not located under the heat source  110  during a film on glass bonding process. Heat generated from the heat source  110  is hardly transmitted to the chip on glass bonding portion  1   a , and the chip on glass bonding portion  1   a  may be prevented from being lifted. 
     A bonding method using the bonding apparatus for the display device according to the exemplary embodiment will be described in further detail with reference to  FIG. 5 . 
     First, a driving chip  2  is bonded to the chip on glass bonding portion  1   a  of the panel  1 . Next, a FPC  3  is located in the film on glass bonding portion  1   b  of the panel  1 . Then, the FPC  3  is bonded to the film on glass bonding portion  1   b  of the panel  1  using a pressure tip  200  of the bonding apparatus for the display device. In this case, no additional heat source is provided in the auxiliary pressure head  400  of the bonding apparatus for the display device according to this exemplary embodiment. Accordingly, the chip on glass bonding portion  1   a  of the panel  1  is not located under the heat source  110  during the film on glass bonding process. Heat generated from the heat source  110  can be hardly transmitted to the chip on glass bonding portion  1   a  of the panel  1 , and the chip on glass bonding portion  1   a  may be prevented from being lifted. 
     The auxiliary pressure head that does not include a heat source is further provided in the pressure head in this exemplary embodiment. However, an auxiliary head source disposed higher than a heat source may be provided in the auxiliary pressure head according to another exemplary embodiment. 
     Hereinafter, another exemplary embodiment will be described in further detail with reference to  FIG. 6 . 
       FIG. 6  is an enlarged side view of a pressure device  20  of a bonding apparatus for a display device according to this exemplary embodiment. 
     The exemplary embodiment shown in  FIG. 6  is substantially equivalent to the exemplary embodiment shown in  FIG. 4 , except that an auxiliary heat source is disposed higher than a heat source in an auxiliary pressure head, and therefore the iterative description will not be repeated. 
     As shown in  FIG. 6 , an auxiliary heat source  410  is provided in an auxiliary pressure head  400  of the bonding apparatus for the display device according to this exemplary embodiment to assist the heat supply. Such an auxiliary heat source  410  is disposed higher than a heat source  110 . Thus, during a film on glass bonding process, heat generated from the auxiliary heat source  410  is hardly transmitted to a chip on glass bonding portion  1   a  of a panel  1 , and the chip on glass bonding portion  1   a  may be prevented from being lifted. 
     In addition, a bottom side of the auxiliary pressure head  400  is higher by a predetermined height h than a bottom side of the pressure head  100 . Thus, during the film on glass bonding process, heat of the auxiliary pressure head  400  is hardly transmitted to the chip on glass bonding portion  1   a  of the panel  1 , and the chip on glass bonding portion  1   a  may be prevented from being lifted. 
     A bonding method using the bonding apparatus for the display device according to this exemplary embodiment will be described in further detail with reference to  FIG. 7 . 
     First, a driving chip  2  is bonded to the chip on glass bonding portion  1   a  of the panel  1 . Next, a FPC is located in the film on glass bonding portion  1   b  of the panel  1 . Then, the FPC  3  is bonded to the film on glass bonding portion  1   b  of the panel  1  using a pressure tip  200  of the bonding apparatus for the display device. In this case, the auxiliary heat source  410  provided in the auxiliary pressure head  400  of the bonding apparatus for the display device according to this exemplary embodiment is disposed higher than the heat source  110 . Accordingly, during the film on glass bonding process, heat generated from the auxiliary heat source  410  is hardly transmitted to the chip on glass bonding portion  1   a  of the panel  1 , and the chip on glass bonding portion  1   a  may be prevented from being lifted. 
     By way of summation and review, a pressure tip of a bonding apparatus used for acquiring good quality of a bonding characteristic may have various types in shape, width, and length. For providing a stable bonding quality, it is desirable that the bonding characteristic be assured and that heat transfer to a bonding portion of the chip on glass and a polarization film be reduced or prevented. 
     During a film on glass bonding process, there is a risk that heat generated from the bonding apparatus could be transferred to an adjacent chip on glass bonding portion that should be prevented from receiving heat higher than a predetermined temperature, such that the chip on glass bonding portion could be lifted, thereby causing a failure. 
     For example, during a film on glass bonding process, heat generated from a pressure head may be transferred to a chip on glass bonding portion adjacent to a lower portion of the pressure head so that the chip on glass bonding portion is lifted. In addition, when the pressure tip has a wide width, heat generated from the pressure tip may be transmitted to the chip on glass bonding portion so that the chip on glass bonding portion is lifted. 
     When the chip on glass bonding portion is lifted, indentation of the chip on glass bonding portion may become obscure so that an electric connection may be disconnected in a portion having a narrow bonding gap, such as a fragile edge part of the chip on glass bonding portion. It may be possible to prevent the chip on glass bonding portion from being lifted by increasing a gap between the FPC and the chip on glass bonding portion. However, in this case, dead space may be increased. 
     According to embodiments, the pressure head of the bonding apparatus for the display device may overlap the pressure tip. The heat source provided in the pressure tip may be located in an upper portion of the pressure tip so that the chip on glass bonding portion of the panel is not located under the heat source during the film on glass bonding process. Accordingly, heat generated from the heat source may hardly be transmitted to the chip on glass bonding portion, thereby reducing the possibility of or preventing the chip on glass bonding portion from being lifted. 
     Further, there may be no need of increasing a gap between the FPC and the chip on glass bonding portion to prevent the chip on glass bonding portion from being lifted, and accordingly an increase in dead space may be avoided. 
     While this disclosure has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the scope thereof 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.