Patent Publication Number: US-2022231211-A1

Title: Display module and display apparatus having the same

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a by-pass continuation of International Application No. PCT/KR2021/001289, filed on Feb. 1, 2021 in the Korean Intellectual Property Receiving Office, which is based on and claims priority to Korean Patent Application No. 10-2021-0006297, filed on Jan. 15, 2021 in the Korean Intellectual Property Office, the disclosures of which are incorporated by reference herein in their entirety. 
    
    
     BACKGROUND 
     1. Field 
     The disclosure relates to a display module and a display apparatus having the same. 
     2. Description of Related Art 
     Display devices, in line with the continuous development direction of high luminance, high resolution, and large-scale display devices, have recently been demanded due to their high efficiency, low power consumption, etc., according to the trend of eco-electronics. 
     As a new display device for replacing a liquid crystal display (LCD) panel, an organic light emitting diodes (OLEDs) display panel attracts attention, but high price, large size, and reliability issues according to a low yield rate are issues to be addressed. 
     There is an increase in the attention to a technique that directly mounts an LED emitting red, green, and blue on a substrate, as a new product to replace or supplement the foregoing. 
     The display device may display an image without a backlight by applying a self-emissive display element, and express various colors while an operation is performed in units of pixels or sub-pixels. An operation of each pixel or sub-pixel is controlled by a thin film transistor (TFT). 
     SUMMARY 
     Provided are a display module with a heat dissipation structure and a display device including the same that prevents heat generated from a plurality of driver integrated circuits (ICs) corresponding to hot spots placed on a back of a substrate from being conducted to the front (e.g., the screen side) of a display module. 
     Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments. 
     According to an aspect of the disclosure, a display module may include a substrate, a ground layer disposed in the substrate, a plurality of self-emissive devices provided on a front surface of the substrate, a first driver integrated circuit (IC) provided on a rear surface of the substrate, and a first heat dissipation structure connected to the ground layer, and including a first ground pad exposed to the rear surface of the substrate. The first heat dissipation structure is configured to dissipate heat to the rear surface of the substrate. 
     The ground layer may be connected to the first ground pad. 
     The first ground pad may be provided adjacent to the first driver IC. The first heat dissipation structure may include a first heat transfer member including a surface in contact with the first ground pad and a first heat dissipation member in contact with a side of the first heat transfer member, and configured to dissipate heat transferred through the first heat transfer member. 
     The first heat transfer member may include a thermal interface material (TIM), and the first heat dissipation member may include graphite. 
     The first heat dissipation member may be configured to overlap the first driver IC. 
     The first heat dissipation member is of a height that may be about the same as the first driver IC. 
     The display module may include a second driver IC disposed in the rear surface of the substrate and adjacent to the first driver IC. The first ground pad may be disposed between the first driver IC and the second driver IC. 
     The display module may include a second heat dissipation structure provided on the rear surface of the substrate. The second heat dissipation structure may include second ground pad disposed between a third driver IC and a fourth driver IC that is adjacent to the third driver IC, and connected to the ground layer, a second heat transfer member including a surface in contact with the second ground pad, and a second heat dissipation member in contact with a side of the second heat transfer member. 
     The display module may further include a second heat transfer member including a surface in contact with a second ground pad. The second heat transfer member is in contact with the first heat dissipation member and the first heat transfer member. 
     The display module may further include an under-fill member disposed between the rear surface of the substrate and the first driver IC, where the under-fill member may include a material configured for heat absorption. 
     The display module may further include an under-fill member disposed between the rear surface of the substrate and the first driver IC, where the under-fill member may include a material configured for insulation. 
     The display module may further include an adhesive member provided on a side surface of the first driver IC in a closed loop shape and between a lower surface of the first driver IC and the rear surface of the substrate, where an air gap may be formed between the lower surface of the first driver IC and the rear surface of the substrate. 
     According to an aspect of the disclosure, a display apparatus may include a support panel, and a plurality of display modules provided on a surface of the support panel. Each display module may include a thin film transistor (TFT) substrate, a micro light emitting diode (LED) provided on a front surface of the TFT substrate, a driver IC provided on a rear surface of the TFT substrate, and a heat dissipation structure connected to a ground layer disposed in the TFT substrate and including a ground pad exposed to the rear surface of the TFT substrate. The heat dissipation structure may be configured to dissipate heat to the rear surface of the TFT substrate. 
     The ground pad may be provided adjacent to the driver IC, and the heat dissipation structure may include a heat transfer member comprising a surface in contact with the ground pad, the heat transfer member including TIMs, and a heat dissipation member in contact with a side of the heat transfer member. The heat dissipation member may be configured to dissipate heat transferred through the heat transfer member, and the heat dissipation member may include graphite. 
     The display apparatus may include an under-fill member disposed between the rear surface of the TFT substrate and the driver IC, where the under-fill member may include a material configured for heat absorption. 
     The display apparatus may include an under-fill member disposed between the rear surface of the TFT substrate and the driver IC, where the under-fill member may include a material configured for insulation. 
     The heat dissipation member may be configured to overlap the driver IC. 
     The heat dissipation member may be of a height that is about the same as the driver IC. 
     The ground layer may be connected to the ground pad. 
     The display apparatus may include an adhesive member provided on a side surface of the driver IC in a closed loop shape and between a lower surface of the driver IC and the rear surface of the TFT substrate, where an air gap may be formed between the lower surface of the driver IC and the rear surface of the TFT substrate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features, and advantages of certain embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a diagram illustrating a display apparatus according to an embodiment of the disclosure; 
         FIG. 2  is a diagram illustrating a display module of a display apparatus according to an embodiment of the disclosure; 
         FIG. 3  is a diagram illustrating a display module of a display apparatus according to an embodiment of the disclosure; 
         FIG. 4  is a diagram illustrating a portion of the display module of  FIG. 3  according to an embodiment; 
         FIG. 5  is a diagram illustrating a rear surface of a display module of a display apparatus showing an example in which a ground pad is exposed to a rear surface of the display module according to an embodiment; 
         FIG. 6  is a diagram illustrating a display module of a display apparatus according to an embodiment of the disclosure; 
         FIG. 7  is a diagram illustrating an example of a heat dissipation structure disposed on a rear surface of a display module of a display apparatus according to an embodiment of the disclosure; 
         FIG. 8  is a diagram illustrating an example of the heat dissipation structure disposed on a rear surface of a display module of a display apparatus according to an embodiment of the disclosure; 
         FIG. 9  is a diagram illustrating an example of forming an insulation structure using an air gap between a substrate and a driver integrated circuit (IC) according to an embodiment; 
         FIG. 10  is a diagram illustrating a view taken along IX-IX line of  FIG. 9  according to an embodiment; and 
         FIG. 11  is a diagram illustrating an example in which a protruding height of a driver IC and heat dissipation member disposed on the rear surface of the substrate are the same according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, various embodiments will be described in detail with reference to the accompanying drawings. The embodiments described herein may be variously modified. Certain embodiments may be described in the drawings and described in detail in the detailed description. However, the specific embodiments disclosed in the accompanying drawings are to facilitate understanding various embodiments. Accordingly, it is to be understood that the present invention is not limited to the specific embodiments disclosed in the accompanying drawings, and it is to be understood that all equivalents or alternatives included within the spirit and scope of the invention are included. 
     In this disclosure, the terms first, second, etc. may be used to describe various components, but these components are not limited by the terms discussed above. The terms described above are used only to distinguish one component from another component. 
     It is to be understood that the terms such as “comprise” may, for example, be used to designate a presence of a characteristic, number, step, operation, element, component, or a combination thereof, and not to preclude a presence or a possibility of adding one or more of other characteristics, numbers, steps, operations, elements, components or a combination thereof. It should be understood that, while certain components are “connected” or “coupled” to other components, they may be directly connected to or coupled to the other components, or other components may be present therebetween. On the other hand, when certain components are referred to as being “directly connected” or “directly coupled” to other components, it should be understood that there are no other components therebetween. 
     In the disclosure, “the same” may refer to components that are matched as well as those that can be different within an extent of the processing error range. 
     When it is decided that a detailed description for the known art related to the disclosure may unnecessarily obscure the gist of the disclosure, the detailed description may be shortened or omitted. 
     A display module may include a display panel with a self-emissive device for displaying a plurality of images. The display module may be one of a flat panel display panel including a plurality of inorganic LEDs, each of which may be about 100 micrometers or below, providing better contrast, response time and energy efficiency compared to liquid crystal display (LCD) panels that require backlight. 
     In the disclosure, a light emitting device for displaying an image provided in a display module may refer to a light emitting diode (LED) having a size of 100 nm or less, which is an inorganic light emitting device. In the disclosure, the LED may be, for example, a mini LED not more than 50 μm, or a micro LED of not more than 30 μm which is smaller than the mini LED. Hereinafter, a micro-inorganic light emitting device provided in a display module of the disclosure is referred to as an “LED”. 
     The LED of the disclosure has brightness, luminous efficiency, and lifetime longer than the organic LED (OLED). The LED may be a semiconductor chip capable of emitting light by itself when power is supplied. The LED has a fast reaction rate, low power, and high luminance. For example, the LED has a higher efficiency for converting electricity to photons compared to an existing LCD or an OLED display. That is, the “brightness per Watt” is greater as compared to existing LCD or OLED displays. The LED of the disclosure may provide the same brightness while consuming less (e.g., substantially half) energy as the existing LED (e.g., an LED having a horizontal, vertical, and height exceeding 100 μm, respectively) or OLED. In addition to the foregoing, the LEDs of the disclosure are capable of providing high resolution, outstanding color, contrast and brightness, may accurately provide a wide range of colors, and may provide a clear screen even in the outdoors under direct and bright sunlight. In addition, the LEDs of the disclosure are resistant to burn-in phenomenon, and generate less heat, thereby improving product lifespan and reducing deformation. The LEDs of the disclosure may have a flip-chip structure in which an anode electrode and a cathode electrode are formed on the same first surface and a light emitting surface is formed on a second surface opposite to a first surface on which the electrodes are formed. 
     The substrate may be disposed with a thin film transistor (TFT)layer formed of a TFT circuit on the front surface, and a power supply circuit to supply power to the TFT circuit and data driving driver, a gate drive driver and a timing controller to control each drive driver may be disposed on a rear surface. A plurality of pixels arranged in the TFT layer may be driven by a TFT circuit. The driving drivers may be bonded directly to the substrate through a chip on board (COB) bonding method. The COB bonding method may refer to a case where the substrate is formed of a synthetic resin. The driving drivers may also be bonded directly to the TFT substrate through a chip on glass (COG) bonding method. In this disclosure, the substrate of the synthetic resin may be, for example, a substrate including materials such as Polyimide (PI), Polyethylene Terephthalate (PET), Polyethersulfone (PES), Polyethylene Naphthalate (PEN), Polycarbonate (PC), or the like. In some cases, the substrate may use a glass substrate or a ceramic substrate. 
     A TFT layer formed with a TFT circuit may be disposed on a front surface of the substrate, and a circuit may not be disposed on a rear surface of the substrate. The TFT layer may be integrally formed on the substrate or may be manufactured in a separate film form to be attached to one surface of the glass substrate. 
     The edge region of the substrate may be the outermost region of the glass substrate. The edge region of the substrate may be a remaining region except for the region in which the circuit of the substrate is formed. The edge region of the substrate may also include a portion of the front surface of the substrate adjacent to the side of the substrate and a rear surface of the substrate adjacent to the side of the substrate. The substrate may be formed of a quadrangle type. The substrate may be formed of rectangle or square. The edge region of the substrate may include at least one of four sides of the glass substrate. 
     According to various embodiments, the TFT forming the TFT layer (or the backplane) is not limited to a specific structure or type. In other words, the TFT may be implemented as a low temperature poly silicon (LTPS) TFT, an oxide TFT, a poly silicon or a-silicon TFT, an organic TFT, and a graphene TFT, or the like, and may be applied to a P type (or N-type) MOSFET in a Si wafer CMOS process. 
     The pixel driving method of the display module may be an active matrix (AM) driving method or a passive matrix (PM) driving method. The display module may form a pattern of wiring in which each LED is electrically connected according to an AM driving method or a PM driving method. 
     A plurality of pulse amplitude modulation (PAM) control circuits may be arranged in a pixel region. In this example, each sub-pixel disposed in a pixel region may be controlled by a corresponding PAM control circuit. A plurality of pulse width modulation (PWM) control circuits may be disposed in a pixel region. In this example, each sub-pixel disposed in a pixel region may be controlled by a corresponding PWM control circuit. 
     A plurality of PAM control circuits and a plurality of PWM control circuits may be arranged in a pixel area. Some of the subpixels arranged in a pixel region may be controlled by the PAM control circuit and the remainder may be controlled through the PWM control circuit. Each sub-pixel may also be controlled by a PAM control circuit and a PWM control circuit. 
     The display module for implementing bezel-less may provide a large-sized multi-display device capable of maximizing an active area when a plurality of displays are connected. Each display module may be configured to maintain a pitch between each of the pixels of the adjacent display module equal to a pitch between each of the pixels in a single display module as the inactive area is minimized. Accordingly, this may be a method in which a seam is not visible in the connection portion between the display modules. 
     The display module may be installed and applied to wearable devices, portable devices, handheld devices in a single unit, and electronic products or electronic parts requiring various displays, and may be applied to display devices such as monitors for personal computer (PC), high-resolution televisions (TVs) and signage (or digital signage), electronic displays, etc. through a plurality of assembly layouts, as a matrix type. 
     Hereinafter, the display module according to an embodiment will be described. 
       FIG. 1  is a diagram illustrating a display apparatus according to an embodiment. 
     Referring to  FIG. 1 , a display device  10  according to one embodiment of the disclosure may connect a plurality of display modules  100  to implement a large size screen, and may include a support panel  20  in which each display module  100  is mounted in a detachable manner. 
     The plurality of display modules  100  may be continuously mounted in a row direction and a column direction on the support panel  20 . The display modules  100  adjacent to each other may be physically and electrically connected through the support panel  20 . 
     The support panel  20  may be provided with a power supply circuit for supplying power to each display module  100 . 
     The display device  10  may form a square of which width to length is the same or a rectangle of which width to length is different, depending on the arrangement of the plurality of display modules  100 . 
       FIG. 2  is a diagram illustrating a display module of a display apparatus according to an embodiment.  FIG. 3  is a diagram illustrating a display module of a display apparatus according to an embodiment. 
     “LED” may refer to an inorganic light emitting device for displaying an image in the size of 100 μm or below, and, in some embodiments, a mini LED having a size of less than or equal to 50 μm, or a micro LED of a size of 30 μm or less, smaller than a mini LED. 
     Referring to  FIGS. 2 and 3 , the display module  100  may include a substrate  110  and a plurality of LED  120  ( 120 R,  120 G, and  120 B) (e.g., micro LEDs) for displaying images arranged on the substrate  110 . Since the plurality of LEDs  120  ( 120 R,  120 G, and  120 B) are self-emissive devices, there is no need for a separate backlight. 
     The substrate  110  may be a TFT substrate including a TFT circuit on a front surface. The TFT circuit may be formed on one surface of the glass substrate or the plastic substrate. 
     The substrate  110  may include a plurality of driver integrated circuits (ICs) (e.g.,  171 ,  172 ,  173 , and  174  of  FIG. 5 ) that supply power to the TFT circuit and are electrically connected with a separate control board placed on a rear surface. 
     The substrate  110  may include an active area to express an image on a front surface. 
     The active area may be partitioned into a plurality of pixel areas  121 , each of which is arranged with a plurality of pixels. The plurality of pixel regions  121  may be divided into various shapes, and may be divided into a matrix. Each pixel region  121  may include a sub-pixel region on which a plurality of sub-pixels are mounted, and a pixel circuit region in which a pixel circuit for driving each sub-pixel is disposed. 
     The plurality of LEDs  120  ( 120 R,  120 G, and  120 B) may be transferred to the pixel circuit area of the TFT layer, and the electrode pads of each micro LED may be electrically connected to the substrate electrode pads formed in the sub-pixel area of the TFT layer. 
     The plurality of substrate electrode pads are electrically connected to a plurality of LEDs  120  ( 120 R,  120 G, and  120 B). The plurality of LEDs  120  ( 120 R,  120 G, and  120 B) may be connected to the TFT circuit through a plurality of substrate electrode pads. 
     The common electrode pad may be formed in a linear shape in consideration of the arrangement of at least three LEDs (e.g.,  120 R,  120 G, and  120 B) located in each pixel area. The plurality of LEDs  120  ( 120 R,  120 G, and  120 B) are subpixels emitting light of red, green, and blue wavelengths, respectively, and may form one pixel  120 . 
     “One micro LED” may refer to an LED having a size of 100 μm or less, which is an inorganic light-emitting device. For example, the micro LED may refer to a mini LED having a size less than or equal to about 50 μm or a micro LED having a size of about 30 μm or less, smaller than the mini LED. The micro LED may refer to “one sub-pixel”, and the corresponding term may be interchangeably used. 
     A red, green, and blue LED  120 R,  120 G, and  120 B, respectively, are described as forming one pixel  120 , but the embodiment is not limited thereto and two or four LEDs may form one pixel. 
     The pixel driving method of the display module  100  according to an embodiment of the disclosure may be an AM driving method or a PM driving method. The display module  100  may form a pattern of wiring in which each LED is electrically connected according to an AM driving method or a PM driving method. 
     The front surface  111  ( FIG. 4 ) of the substrate  110  may be laminated with a transparent layer  130  to protect a plurality of LEDs  120  ( 120 R,  120 G, and  120 B) from contamination caused by foreign objects, external shocks, or the like. 
     The transparent layer  130  may be formed of a transparent material that does not affect or minimize effect on light emission of a plurality of LEDs  120  ( 120 R,  120 G, and  120 B), which are light-emissive devices. 
       FIG. 4  is a diagram illustrating a portion of the display module of  FIG. 3  according to an embodiment.  FIG. 5  is a diagram illustrating a rear surface of a display module of a display apparatus showing an example in which a ground pad is exposed to a rear surface of the display module according to an embodiment.  FIG. 6  is a diagram illustrating a display module of a display apparatus according to an embodiment. 
     The plurality of driver ICs  171 ,  172 ,  173 ,  174  placed on the rear surface  113  of the substrate  110  may correspond to hot spots having a high heat dissipation in the display module  100 . The display module  100  may have a heat dissipation structure  200  that can minimize the heat generated by a plurality of driver ICs  171 ,  172 ,  173 , and  174  being emitted to the front of the display module  100 . 
     The heat dissipation structure  200  provided in the display module  100  will be described with reference to drawings. 
     The heat dissipation structure  200  disposed on the rear surface of the display module  100  may include a ground pad  230 , a heat transfer member  250 , and a heat dissipation member  270 . 
     The ground pad  230  may be exposed to the rear surface  113  of the substrate  110  and may be connected to a ground layer  150  through a via-wiring  210  formed in a via-hole. The ground pad  230  may be made of the same metal material as the ground layer  150 . 
     The ground pad  230  of which a surface exposed to the outside may be located on the same plane as the rear surface  113  of the substrate  110 . Accordingly, the ground pad  230  may be formed on the substrate  110  such that a part other than the exposed surface is inserted into the substrate  110 . 
     A plurality of ground layers may be disposed on the substrate  110 . The plurality of ground layers may be interconnected the via-wirings. In this example, the ground layer  150  connected to the ground pad  230  may be a ground layer closest to the rear surface  113  of the substrate  110 . 
     The ground pad  230  may be disposed most adjacent to the driver IC  171  corresponding to the hot spot. The arrangement of the ground pads  230  is considered to be capable of directly absorbing the heat conducted along the rear surface  113  of the substrate  110  to the ground pad  230  by generating the ground pad  230  in the driver IC  171 . 
     The ground pad  230  may be disposed between the two driver ICs  171  and  172  as shown in  FIG. 5 . Accordingly, the ground pad  230  may be disposed adjacent to the two driver ICs  171  and  172 . 
     The space of the ground pad  230  may be formed to be greater than or equal to the space of the surface in contact with the heat transfer member  250 . 
     The ground pad  230  is illustrated as square but the embodiment is not limited thereto and may be formed in various forms such as polygonal, round, oval, or the like. 
     The heat transfer member  250  may be formed of a composite material with excellent thermal conductivity. For example, the heat transfer member  250  may be thermal interface materials (TIM). 
     The heat transfer member  250  transfers, to the heat dissipation member  270 , the heat conducted from the ground layer  150  to the ground pad  230 . The heat transfer member  250  may have both surfaces disposed at opposite sides being in close contact with the ground pad  230  and the heat dissipation member  270 . The heat transfer member  250  may prevent voids from being formed at the interface between the ground pad  230  and the interface between the heat dissipation member  270 , thereby maximizing thermal conduction efficiency by minimizing the thermal contact resistance caused by voids. 
     The heat dissipation member  270  may be formed in an approximate plate shape. The heat dissipation member  270  may be formed of graphite. 
     The thermal conductivity of the graphite is twice that of iron at room temperature, one-third of the copper, two-third of the aluminum, which is very high, and the thermal expansion rate is significantly less than that of iron, copper, aluminum, and ceramic so as to have an optimal condition of heat dissipation. 
     Referring to  FIG. 4 , the heat dissipation member  270  may be supported by the heat transfer member  250  and may be disposed at a second protruding height H 2  that is higher than the first protruding height H 1  of the driver IC  171  (e.g., H 1 &lt;H 2 ). The first protruding height H 1  may be the height from the rear surface  113  of the substrate  110  to the upper surface  300  of the driver IC  171 , and the second protruding height H 2  may be the height from the rear surface  113  of the substrate  110  to the upper surface  310  of the heat dissipation member  270 . 
     As described above, since the second protrusion height H 2  of the heat dissipation member  270  is higher than the first protruding height H 1  of the driver IC  171 , as shown in  FIG. 6 , the heat dissipation member  270  may overlap at least a portion of the driver IC  171 . Accordingly, the heat-dissipation member  270  may not be interfered by the driver IC  171 , thereby securing a wide heating area. 
     The heat dissipation member  270  is approximately illustrated as square shape, but the embodiment is not limited thereto, and the heat dissipation member  270  may be formed in various shapes in consideration of surrounding structures. 
     The second protruding height H 2  of the heat dissipation member  270  may be determined by the thickness of the heat transfer member  250 . When the heat dissipation member  270  is overlapped with the driver IC  171 , if the thickness of the heat dissipation member  250  is adjusted, the heat dissipation member  270  may be spaced apart from the upper surface  300  of the driver IC  171  at a predetermined interval, or may be in contact with the upper surface  300  of the driver IC  171 , as shown in  FIG. 4 . 
     A substantial portion of the total heat emitted from the driver IC  171  may be absorbed into the ground layer  150  through a plurality of ball grids  171   a , and the remaining heat may be emitted to the top and side of the driver IC  171 . In this example, the heat emitted to the upper surface  300  and the side surface of the driver IC  171  may be directly absorbed into the heat dissipation member  270  overlapping the driver IC  171 . 
     The thermal conductivity path through which heat generated from the driver IC  171  is discharged through the heat dissipation member  270  is as follows. 
     When the driver IC  171  is driven, the heat generated by the driver IC  171  is conducted through a plurality of ball grids  171   a  to the inside of the substrate  110  in the direction shown in  FIG. 4 . The heat conducted through the plurality of ball grids  171   a  is mostly absorbed into the ground layer  150  that is disposed closes to the plurality of ball grids  171   a  on the back surface  113  of the substrate  110 . The heat absorbed to the ground layer  150  is conducted to the ground pad  230  through the via-wiring  210 , and then is conducted to the heat dissipation member  270  through the heat transfer member  250 . The heat dissipation member  270  emits heat to the air by convection current. 
     When the heat dissipation member  270  is in contact with or adjacent to the peripheral structure, some of the heat emitted from the heat dissipation member  270  may be absorbed into the periphery structure. 
     As described above, the heat emitted from the driver IC  171  is discharged to the rear side of the display module  100  by the heat dissipation structure provided on the rear surface of the substrate  110 , thereby fundamentally preventing heat from being emitted to the front (screen side) of the display module  100 . The display device  10  according to the disclosure may satisfy the conditions of the home TV used indoors. 
       FIG. 7  is a diagram illustrating an example of a heat dissipation structure disposed on a rear surface of a display module of a display apparatus according to an embodiment. 
     A plurality of heat dissipation structures may be disposed on the rear surface  113  of the substrate  110 . 
     Referring to  FIG. 7 , the heat dissipation structure  200  is disposed between the first and second driver ICs  171  and  172 , and the additional heat dissipation structure  200   a  may be disposed between the third and fourth driver ICs  173  and  174 . 
     The ground pad  230  of the heat dissipation structure  200  is disposed between the first and second driver ICs  171  and  172  so as to be adjacent to the first and second driver ICs  171  and  172 , respectively. The heat dissipation member  270  may be formed so that both sides overlap a portion of the first and second driver ICs  171  and  172 , respectively. The heat dissipation member  270  may be connected to the ground pad  230  through a heat transfer member. 
     The additional heat dissipation structure  200   a  may include the same structure as the first heat dissipation structure  200 . The ground pad  230   a  of the additional heat dissipation structure  200   a  is disposed between the first and second driver ICs  171  and  172  to be adjacent to the first and second driver ICs  171  and  172 , respectively. The ground pad  230   a  may be connected to a ground layer disposed closest to the rear surface  113  of the substrate  110  through a via-wiring. 
     The heat dissipation member  270   a  may be formed to overlap a portion of the third and fourth driver ICs  173  and  174 , respectively. The heat dissipation member  270   a  may be connected to the ground pad  230   a  through a heat transfer member. 
       FIG. 8  is a diagram illustrating an example of the heat dissipation structure disposed on a rear surface of a display module of a display apparatus according to an embodiment. 
     A heat dissipation structure is provided in which a plurality of exposed ground pads are disposed on the rear surface  113  of the substrate  110 , and a plurality of ground pads are connected to one heat dissipation member through a plurality of heat dissipation member. 
     Referring to  FIG. 8 , the heat dissipation structure  200   c  may include a plurality of ground pads  230   c , a plurality of heat transfer members corresponding to each ground pad  230   c , and one heat dissipation member  270   c  connected to the plurality of heat transfer members. 
     The four ground pads  230   c  may be disposed between the four driver ICs  171 ,  172 ,  173 , and  174 . As shown in  FIG. 8 , each ground pad  230   c  may be disposed between a pair of driver ICs adjacent to each other. Each ground pad  230   c  may be connected to a ground layer disposed closest to the back surface  113  of the substrate  110  through a via-wiring. 
     The one heat dissipation member  270   c  may overlap one portion of the four driver ICs  171 ,  172 ,  173 , and  174 , respectively. The heat dissipation member  270   c  may have a larger heating area than the heat dissipation members  270  and  270   a  described above. 
     Referring to  FIG. 4 , an under-fill member  190  is filled between the rear surface  113  of the substrate  110  and the driver ICs  171 ,  172 ,  173 , and  174  to be protected from external physical impact and moisture. 
     The material of the under-fill member  190  may be changed to prevent the heat emitted from the respective driver IC&#39;s  171 ,  172 ,  173 , and  174  from being conducted to the front side of the substrate  110 . 
     For example, when the under-fill member  190  is applied with a material having heat absorption, heat emitted from the plurality of ball grids  171   a  may be mostly absorbed to the under-fill member  190  and then discharged to the air around the driver IC  171  by convection. 
     In addition, when the under-fill member  190  is applied with a material having insulation, heat conducted to the substrate  110  through the plurality of ball grids  171   a  may be minimized by the under-fill member  190 . 
       FIG. 9  is a diagram illustrating an example of forming an insulation structure using an air gap between a substrate and a driver integrated circuit (IC) according to an embodiment.  FIG. 10  is a diagram illustrating a view taken along IX-IX line of  FIG. 9  according to an embodiment. 
     Referring to  FIGS. 9 and 10 , as an additional heat dissipation structure, an adhesive member  191  that may replace the under-fill member may be provided and an air gap  193  may be formed between the driver IC  171  and the rear surface  113  of the substrate  110 . 
     As shown in  FIG. 9 , the adhesive member  191  may be formed in a closed loop shape so as to surround the side surface  171   b  of the driver IC  171 . The adhesive member  191  is formed to surround the side surface  171   b  of the driver IC  171  in the form of a closed loop, thereby sealing between the bottom surface of the driver IC  171  (facing the rear surface of the substrate) and the rear surface  113  of the substrate  110 . Accordingly, the adhesive member  191  may protect the rear surface  113  of the substrate  110  and the driver IC  171  from external physical impact and moisture, or the like. 
     The adhesive member  191  may fix the driver IC  171  to the rear surface  113  of the substrate  110  stably. The adhesive member  191  may have a predetermined flexibility and insulation. 
     The air gap  193  formed between the driver IC  171  and the rear surface  113  of the substrate  110  may serve as an insulating layer for blocking heat generated by the driver IC  171 . Accordingly, it is possible to minimize the heat generated by the driver IC  171  from being conducted to the front of the substrate  110 . 
     The heat dissipation structure  200  described above has a second protruding height H 2  of the heat dissipation member  270  higher than the first protruding height H 1  of the driver IC  171 . The protruding height of the heat dissipation member  270  may not be limited thereto. 
       FIG. 11  is a diagram illustrating an example in which a protruding height of a driver IC and heat dissipation member disposed on the rear surface of the substrate are the same according to an embodiment. 
     Referring to  FIG. 11 , a heat dissipation structure  200   d  disposed on the rear surface  113  of the substrate  110  may have a third protruding height H 3  of the heat dissipation member  270   d  equal to the first protruding height H 1  of the driver IC  171 . 
     The first protruding height H 1  may be the height from the rear surface  113  of the substrate  110  to the upper surface  300  of the driver IC  171 , and the third protruding height H 3  may be the height from the rear surface  113  of the substrate  110  to the upper surface  320  of the heat dissipation member  270   d . The upper surface  300  of the driver IC  171  and the upper surface  320  of the heat dissipation member  270   d  may be located on the same plane. 
     The third protruding height H 3  of the heat dissipation member  270   d  may be adjusted by forming the thickness of the heat transfer member  250 D thinner than the thickness of the heat transfer member  250  ( FIG. 4 ) described above. 
     When the third protruding height H 3  of the heat dissipation member  270   d  is formed to be equal to the first protruding height H 1  of the driver IC  171 , the thickness of the display module  100  may be reduced. 
     As described above, the heat generated from the plurality of driver ICs  171 ,  172 ,  173 , and  174  corresponding to the hot spot through the heat dissipation structure formed on the rear surface  113  of the substrate  110  may be prevented from being conducted to the front (e.g., screen side) of the display module  100  or minimized. 
     The various embodiments have been described individually, but it is not necessary that each embodiment is implemented as a sole embodiment, but configurations and operations of each embodiment may be implemented in combination with at least one other embodiment. 
     While preferred embodiments of the disclosure have been shown and described, the disclosure is not limited to the aforementioned specific embodiments, and it is apparent that various modifications can be made by those having ordinary skill in the technical field to which the disclosure belongs, without departing from the gist of the disclosure as claimed by the appended claims. Also, it is intended that such modifications are not to be interpreted independently from the technical idea or prospect of the disclosure.