Display module including bonding member connecting light emitting diode and substrate

Abstract

A display module is provided. The display module includes a substrate divided into a plurality of pixel areas and including a plurality of electrode pads disposed in the pixel areas; a bonding member including an adhesive layer stacked on one surface of the substrate and a plurality of conductive balls disposed in the adhesive layer; and a plurality of light emitting diodes including electrodes connected to the plurality of electrode pads through a plurality of conductive balls, in which the plurality of conductive balls are patterned into conductive regions corresponding to the plurality of electrode pads.

Description

Technical Field

[0001] Apparatuses and methods consistent with the present disclosure relate to a display module including a bonding member electrically and physically connecting a light emitting diode and a substrate. Background Art

[0002] The display panel includes: a substrate on which a plurality of thin film transistors (TFTs) are disposed; and a plurality of light emitting diodes mounted on the substrate. The plurality of light emitting diodes may be inorganic light emitting diodes that emit light of their own accord. The plurality of light emitting diodes present various colors when operated in units of pixels or sub-pixels. The operation of each pixel or sub-pixel is controlled by a plurality of TFTs. The respective light emitting diodes emit various colors, such as red, green, and blue. Summary of the invention

[0003] When using inorganic light emitting diodes having a size of 100 μm or less, the placement density of the inorganic light emitting diodes can be such that the electrical connection pads and the corresponding conductive balls are close to each other. This occurs for diodes placed with fine pitch (500 μm or less) or ultra-fine pitch (pitch is less than fine pitch). The problem solved herein is that during the manufacture of a display module, the conductive balls may not provide good contact and / or may aggregate together. An embodiment provides an anisotropic conductive film with good contact and without the conductive balls aggregated together, thereby solving this problem. Some embodiments include using grooves in a molded substrate to control the alignment of the conductive balls.

[0004] A display module according to an example of the present disclosure includes: a substrate divided into a plurality of pixel areas and including a plurality of electrode pads arranged in the pixel areas; a bonding member including an adhesive layer stacked on one surface of the substrate and a plurality of conductive balls arranged in the adhesive layer; and a plurality of light emitting diodes including electrodes connected to the plurality of electrode pads through the plurality of conductive balls, wherein the plurality of conductive balls are patterned into conductive areas corresponding to the plurality of electrode pads.

[0005] The pattern of the plurality of conductive balls may be a stripe pattern in which conductive regions are disposed in pixel regions adjacent to each other and connect the plurality of electrode pads in a straight line.

[0006] The pattern of the plurality of conductive balls may be an island pattern in which conductive regions are independently disposed in the plurality of pixel regions, respectively.

[0007] The pixels arranged in the plurality of pixel regions may include a plurality of sub-pixels. The conductive region arranged in each of the plurality of pixel regions may include a plurality of sub-conductive regions corresponding to the plurality of sub-pixels. The plurality of sub-conductive regions may be spaced apart from each other.

[0008] At least two of the plurality of conductive balls may be aligned in a thickness direction of the adhesive layer.

[0009] A bonding member according to an example of the present disclosure is connected between an electrode of a light-emitting diode and an electrode pad of a display substrate. The bonding member includes: an adhesive layer; and a plurality of conductive balls disposed in the adhesive layer. The plurality of conductive balls are patterned as a conductive region in a portion of the entire region of the bonding member.

[0010] The joining member may further include an additional adhesive layer stacked on the adhesive layer.

[0011] The adhesive layer may have a black base color.

[0012] A manufacturing method for a joining member according to an example of the present disclosure includes: forming a mold substrate having a plurality of grooves patterned in one surface of the mold substrate; aligning a plurality of conductive balls in the plurality of grooves; disposing the mold substrate to correspond to an adhesive layer so that the plurality of conductive balls face the adhesive layer; and disposing the plurality of conductive balls in the adhesive layer by pressing the mold substrate against the adhesive layer.

[0013] In a thickness direction of the mold substrate, a depth (D) of the plurality of grooves may be at least twice a diameter of the plurality of conductive balls.

[0014] A surface treatment for preventing the conductive balls from attaching may be performed on a region where the plurality of grooves are not formed in one surface of the mold substrate. The surface treatment may be a plasma treatment for forming fine concavoconvexities, or may be a hydrophobic treatment.

[0015] Before aligning the plurality of conductive balls in the plurality of grooves, an adhesive may be applied to the plurality of grooves. Therefore, the plurality of conductive balls may be easily aligned in the plurality of grooves.

[0016] A plurality of holes communicating with the plurality of grooves may be formed on the other surface of the mold substrate. When the plurality of conductive balls are aligned in the plurality of grooves, negative pressure may be formed in the plurality of grooves through the plurality of holes to insert the plurality of conductive balls into the plurality of grooves.

[0017] In some embodiments of the manufacturing method, the plurality of conductive balls in the plurality of recesses are configured to support electrical connection of inorganic light emitting diodes disposed at ultra-fine pitches on a substrate of a display module.

[0018] In some embodiments of the manufacturing method, the plurality of grooves are in the mold substrate, and the plurality of grooves are treated with plasma to prevent the plurality of conductive balls from adhering to the mold substrate.

[0019] In some embodiments of the manufacturing method, the display module includes a display driver integrated circuit (IC) for controlling a substrate, and the process includes mounting an inorganic light emitting diode on the substrate of the display module.

[0020] In some embodiments of the manufacturing method, the inorganic light emitting diode is in the form of a micro LED chip, the substrate of the display module is an anisotropic conductive film (ACF), and the process includes mounting the micro LED chip onto the ACF using a thermocompression bonding process. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a block diagram illustrating a display device according to one example of the present disclosure.

[0022] Figure 2 is a plan view showing a display module according to one example of the present disclosure.

[0023] Figure 3 yes Figure 2 An enlarged view of portion A is shown in FIG.

[0024] Figure 4 is along Figure 3 A cross-sectional view taken along line BB'.

[0025] Figures 5 to 9 is a diagram showing a pattern of a joining member according to one example of the present disclosure.

[0026] Figures 10 to 12 is a diagram illustrating a joining member according to one example of the present disclosure.

[0027] Fig.13 is a flowchart illustrating a method of manufacturing a joined member according to one example of the present disclosure.

[0028] Fig.14 is a plan view showing a molded substrate for manufacturing a joined member according to one example of the present disclosure.

[0029] Fig.15 is along Fig.14 A cross-sectional view taken along line CC'.

[0030] Figures 16 to 18 is a diagram illustrating a process of manufacturing a joined member according to one example of the present disclosure.

[0031] Fig.19 is a cross-sectional view showing a molded substrate for manufacturing a joined member according to one example of the present disclosure.

[0032] Fig. 20 is a diagram showing an example of aligning a plurality of conductive balls in a plurality of grooves of a mold substrate by using vacuum adsorption. DETAILED DESCRIPTION

[0033] Hereinafter, various embodiments will be described in more detail with reference to the accompanying drawings. The embodiments mentioned in the specification may be modified in various ways. Specific embodiments may be shown in the accompanying drawings and described in detail in the specific embodiments. However, the specific embodiments shown in the accompanying drawings are provided only to enable easy understanding of the various embodiments. Therefore, it should be understood that the spirit of the present disclosure is not limited to the specific embodiments shown in the accompanying drawings, and includes all equivalents and substitutes contained in the spirit and scope of the present disclosure.

[0034] In the present disclosure, terms including ordinal numbers such as "first", "second", etc. may be used to describe various components. However, these components are not limited by these terms. These terms are only used to distinguish one component from another component.

[0035] It will also be understood that the terms "comprising" or "having" used in the present disclosure specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof mentioned in the present specification, but do not exclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof. It should be understood that where a component is referred to as being "connected to" or "coupled to" another component, a component may be directly connected to or directly coupled to the other component, or connected to or coupled to the other component through other components intervening therebetween. On the other hand, it should be understood that where a component is referred to as being "directly connected to" or "directly coupled to" another component, the one component may be connected to or coupled to the other component without other components intervening therebetween.

[0036] In the present disclosure, the expression “same” includes not only being completely identical but also including a difference taking into account a matching error range.

[0037] Furthermore, in describing the present disclosure, in the case where it is determined that the detailed description of known functions or configurations related to the present disclosure may unnecessarily obscure the gist of the present disclosure, the detailed description thereof will be simplified or omitted.

[0038] According to one example, a display module may include a substrate and a plurality of image displaying light emitting diodes arranged on the substrate.

[0039] According to one example, the light-emitting diode included in the display module may be an inorganic light-emitting diode having a size of 100 μm or less. For example, the inorganic light-emitting diode may be a micro light-emitting diode (LED) or a mini LED, but is not limited thereto. Compared with an organic light-emitting diode (hereinafter referred to as "OLED"), an inorganic light-emitting diode has higher brightness, higher luminous efficiency, and longer life. An inorganic light-emitting diode may be a semiconductor chip that can emit light based on the power supplied thereto. Inorganic light-emitting diodes have fast reaction speed, low power consumption, and high brightness. In the case where the inorganic light-emitting diode is a micro LED, the efficiency of converting electricity into photons may be higher than that of a liquid crystal display (LCD) or an OLED. For example, a micro LED may have a higher "brightness per watt" than an LCD or OLED display. Therefore, compared with an LED or OLED having a size of more than 100 μm, a micro LED can produce the same brightness with about half the energy. Micro LEDs can achieve high resolution and excellent color, contrast, and brightness, so a wide range of colors can be accurately expressed, and a clear screen can be achieved even outdoors that is brighter than indoors. Since micro LEDs are not prone to screen burn-in and generate little heat, the long life of the micro LEDs can be ensured without deformation of the micro LEDs.

[0040] According to one example, the light emitting diode may be formed in a flip chip form in which an anode electrode and a cathode electrode are provided on a surface opposite to a light emitting surface.

[0041] According to one example, a thin film transistor (TFT) layer formed with a TFT circuit may be disposed on a first surface of a substrate (e.g., a front surface of the substrate). A power supply circuit, a data driver, a gate driver, and a timing controller for controlling each driver that supplies power to the TFT circuit may be disposed on a second surface of the substrate (e.g., a rear surface of the substrate). The substrate may have a plurality of pixels arranged on the TFT layer. Each pixel may be driven by a TFT circuit.

[0042] According to one example, the TFT formed in the TFT layer may be a low temperature polycrystalline silicon (LTPS) TFT, a low temperature polycrystalline oxide (LTPO) TFT, or an oxide TFT.

[0043] According to one example, the substrate on which the TFT layer is disposed may be a glass substrate, a flexible synthetic resin-based substrate such as polyimide (PI), polyethylene terephthalate (PET), polyethersulfone (PES), polyethylene naphthalate (PEN), or polycarbonate (PC), or a ceramic substrate.

[0044] According to one example, the TFT layer of the substrate may be integrally formed with the first surface of the substrate, or may be manufactured in the form of a separate film and attached to the first surface of the substrate.

[0045] According to one example, the first surface of the substrate may be divided into an active area and an inactive area. The active area may be an area occupied by the TFT layer in the entire area of ​​the first surface of the substrate. The inactive area may be an area other than the active area in the entire area of ​​the first surface of the substrate.

[0046] According to one example, the edge region of the substrate may be the outermost region of the substrate. For example, the edge region of the substrate may include a region corresponding to the side surface of the substrate, a partial region of the first surface of the substrate adjacent to the side surface, and a partial region of the second surface of the substrate. A plurality of side wirings may be provided in the edge region of the substrate, the side wirings electrically connecting the TFT circuit on the first surface of the substrate and the drive circuit on the second surface of the substrate.

[0047] According to one example, the substrate may be a quadrilateral substrate. For example, the substrate may be a rectangular substrate or a square substrate.

[0048] According to one example, the TFT disposed on the substrate may be implemented by, for example, an oxide TFT, a Si TFT (polysilicon or amorphous silicon), an organic TFT, or a graphene TFT in addition to being implemented by a low temperature polysilicon TFT (LTPS TFT). The TFT may be applied by producing only a P-type (or N-type) metal oxide semiconductor field effect transistor (MOSFET) in a Si wafer complementary metal oxide semiconductor (CMOS) process.

[0049] According to one example, a TFT layer in which a TFT circuit is formed may be omitted in the substrate. In this case, a plurality of micro integrated circuit (IC) chips serving as the TFT circuit may be mounted on the first surface of the substrate. In this case, the plurality of micro IC chips may be electrically connected to a plurality of light emitting diodes arranged on the first surface of the substrate through wiring.

[0050] According to one example, the pixel driving method of the display module may be an active matrix (AM) driving method or a passive matrix (PM) driving method.

[0051] According to one example, the display module can be installed in and applied to wearable devices, portable devices, handheld devices, and electronic products or electrical components that require various displays.

[0052] According to one example, a display device such as a personal computer monitor, a high-definition television, a sign (or digital sign), and an electronic display is provided by connecting a plurality of display modules in a grid form.

[0053] According to one example, a pixel may include multiple light emitting diodes. In this case, a light emitting diode may be a sub-pixel. In the present disclosure, a "light emitting diode", a "micro-LED" and a "sub-pixel" may be used interchangeably as the same meaning.

[0054] Hereinafter, an example will be described in detail with reference to the accompanying drawings so that a person skilled in the art to which the present disclosure belongs can easily practice the present disclosure. However, the example can be modified in various different forms and is not limited to the example described herein. In the accompanying drawings, parts irrelevant to the description will be omitted to clearly describe the example of the present disclosure, and similar reference numerals will be used throughout the specification to describe similar parts.

[0055] Hereinafter, a display device according to one example of the present disclosure will be described with reference to the accompanying drawings.

[0056] Figure 1 is a block diagram illustrating a display device according to one example of the present disclosure.

[0057] refer to Figure 1 According to an example of the present disclosure, a display device 1 may include a display module 3 and a processor 5 .

[0058] The display module 3 can display various images. Here, the image is a concept including still images and / or moving images. The display module 3 can display various images, such as broadcast content and multimedia content. In addition, the display module 3 can display user interfaces and icons.

[0059] The display module 3 may include a substrate 40 and a display driver integrated circuit (IC) 7 for controlling the substrate 40 .

[0060] The display driver IC 7 may include an interface module 7a, a memory 7b (e.g., a buffer memory), an image processing module 7c, or a mapping module 7d. The display driver IC 7 may receive, for example, image data or image information from other components of the display device 1 through the interface module 7a, the image information including an image control signal corresponding to a command for controlling the image data. For example, the image information may be received from a processor 5 (e.g., a main processor (e.g., an application processor) or an auxiliary processor (e.g., a graphics processing unit) that operates independently of the functions of the main processor).

[0061] The display driver IC 7 may store at least a portion of the received image information in the memory 7b, for example, in units of frames. The image processing module 7c may perform pre-processing or post-processing (e.g., resolution, brightness, or size adjustment) on at least a portion of the image data based on characteristics of the image data or characteristics of the substrate 40. The mapping module 7d may generate a voltage value or a current value corresponding to the image data pre-processed or post-processed by the image processing module 7c. According to one example, the generation of the voltage value or the current value may be performed at least in part based on, for example, the properties of the pixels arranged on the substrate 40 (e.g., the arrangement of the pixels (RGB stripe structure or RGB pentile structure) or the size of each sub-pixel). At least some of the pixels of the substrate 40 are driven at least in part based on the voltage value or the current value, and therefore, visual information corresponding to the image data (e.g., text, an image, or an icon) may be displayed through the substrate 40.

[0062] The display driver IC 7 may send a drive signal (eg, a driver drive signal or a gate drive signal) to the display based on the image information received from the processor 5 .

[0063] The display driver IC 7 may display an image based on the image signal received from the processor 5. For example, the display driver IC 7 may generate drive signals of a plurality of sub-pixels based on the image signal received from the processor 5, and display an image by controlling light emission of the plurality of sub-pixels based on the drive signals.

[0064] The display module 3 may also include a touch circuit (not shown). The touch circuit may include a touch sensor and a touch sensor IC for controlling the touch sensor. The touch sensor IC may control the touch sensor to detect, for example, a touch input or a hovering input for a specified position in the substrate 40. For example, the touch sensor IC may detect a touch input or a hovering input by measuring a signal change (such as voltage, light amount, resistance, or charge amount) for a specified position in the substrate 40. The touch sensor IC may provide information (such as position, area, pressure, or time) about the detected touch input or hovering input to the processor 5. According to one example, at least a portion of the touch circuit (such as a touch sensor IC) may be included as a display driver IC 7, a portion of the substrate 40, or another component (such as an auxiliary processor) disposed outside the display module 3.

[0065] The processor 5 may be implemented by a digital signal processor (DSP) that processes a digital image signal, a microprocessor, a graphics processing unit (GPU), an artificial intelligence (AI) processor, a neural processing unit (NPU), or a time controller (TCON). However, the processor 5 is not limited thereto, and may include one or more of a central processing unit (CPU), a microcontroller unit (MCU), a microprocessing unit (MPU), a controller, an application processor (AP), a communication processor (CP), and an ARM processor, or may be defined by these terms. In addition, the processor 5 may be implemented by a system on chip (SoC) or a large-scale integration (LSI) embedded with a processing algorithm, or may be implemented in the form of an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

[0066] The processor 5 may drive an operating system or an application program to control hardware or software components connected to the processor 5, and may perform various types of data processing and calculations. In addition, the processor 5 may load a command or data received from at least one other component into a volatile memory and process it, and may store various data in a nonvolatile memory.

[0067] The display module 3 may be a touch screen coupled with a touch sensor, a flexible display, a rollable display and / or a three-dimensional display.

[0068] Figure 2 is a plan view showing a display module according to one example of the present disclosure. Figure 3 is a diagram showing a portion of a display module according to an example of the present disclosure (eg, Figure 2 A) An enlarged view of the portion shown. Figure 4 is a cross section (eg, along the Figure 3 FIG. 1 is a diagram of a cross section taken along line BB' of FIG. 1 .

[0069] refer to Figure 2 and Figure 3 , the display module 3 may include a substrate 40 and a plurality of pixels 100 disposed on a first surface of the substrate 40. For example, the plurality of pixels 100 may be respectively arranged in pixel regions 101 arranged in a matrix form on the substrate 40.

[0070] A thin film transistor (TFT) circuit electrically connected to the plurality of pixels 100 may be disposed on the first surface of the substrate 40. The TFT disposed on the substrate 40 may be an amorphous silicon (a-Si) TFT, a low temperature polycrystalline silicon (LTPS) TFT, a low temperature polycrystalline oxide (LTPO) TFT, a mixed oxide and polycrystalline silicon (HOP) TFT, a liquid crystal polymer (LCP) TFT, or an organic TFT (OTFT).

[0071] refer to Figure 3 , each of the plurality of pixels 100 may include at least three sub-pixels. The sub-pixels may be, for example, micro-LEDs which are inorganic light-emitting diodes. Hereinafter, for convenience, the sub-pixels are referred to as micro-LEDs. Here, the micro-LED may be defined as an LED having a size of 100 μm or less or 30 μm or less.

[0072] Each pixel 100 may include a first micro LED 110 emitting light in a red wavelength band, a second micro LED 120 emitting light in a green wavelength band, and a third micro LED 130 emitting light in a blue wavelength band.

[0073] In each pixel 100, a first micro LED 110, a second micro LED 120, and a third micro LED 130 may be disposed in a pixel region 101 divided in a substrate 40. A plurality of TFTs for driving the first to third micro LEDs 110, 120, and 130 may be disposed in a region not occupied by the first to third micro LEDs 110, 120, and 130 in the pixel region.

[0074] The first to third micro LEDs 110, 120, and 130 may be arranged in a row at regular intervals, but are not limited thereto. For example, the first to third micro LEDs 110, 120, and 130 may be arranged in an L letter shape or a pentileRGBG layout. The Pentile RGBG layout is a layout in which sub-pixels are arranged in such a manner that the number of red, green, and blue sub-pixels is a ratio of 1:1:2 (RGBG) based on the cognitive characteristics that people recognize green better than blue. The Pentile RGBG layout can increase production and reduce unit cost. The Pentile RGBG layout can achieve high resolution on a small screen.

[0075] One pixel 100 is described as including three micro LEDs 110, 120, and 130, but is not limited thereto. For example, one pixel 100 may include one micro LED or four or more micro LEDs (eg, red, green, blue, and white LEDs).

[0076] refer to Figure 4 , a plurality of electrode pads 41 and 42 may be arranged in pairs at intervals on one surface 401 of the substrate 40. The plurality of electrode pads 41 and 42 may be electrically connected to the first electrode 111 and the second electrode 112 of the first micro LED 110, respectively.

[0077] The bonding member 70 may be stacked on one surface 401 of the substrate 40. The bonding member 70 may include an adhesive layer 71 and a plurality of fine conductive balls 75 included in the adhesive layer 71. The adhesive layer 71 may be formed of a thermosetting material (e.g., epoxy resin, polyurethane resin, or acrylic resin). Alternatively, the adhesive layer 71 of the bonding member 70 may be a non-conductive film (NCF) or a non-conductive paste (NCP). The plurality of conductive balls 75 may have a fine size (e.g., about 3 μm to 15 μm), and include polymer particles and a conductive film (e.g., gold (Au), nickel (Ni), or lead (Pd)) coating the peripheral surface of the polymer particles with a predetermined thickness.

[0078] refer to Figure 3 , a plurality of conductive balls 75 may be arranged in a predetermined pattern within the adhesive layer 71. The pattern may correspond to a conductive region 73, wherein the plurality of conductive balls 75 correspond to the plurality of electrode pads 41 and 42. In this case, the pattern of the conductive region 73 may be a stripe pattern, wherein the plurality of electrode pads 41 and 42 disposed in the pixel regions 101 adjacent to each other are connected in a straight line. In some embodiments, each of the conductive regions disposed in the respective pixel regions includes a plurality of sub-conductive regions corresponding to the plurality of sub-pixels. A pattern connecting the corresponding pixel regions 101 in a straight line may be formed in a vertical direction along the arrangement direction of the first to third micro LEDs 110, 120, and 130.

[0079] Since the plurality of conductive balls 75 are patterned in such a manner as to be limitedly positioned in a portion of the entire area of ​​the adhesive layer 71, the manufacturing cost of the bonding member 70 can be reduced by reducing the number of conductive balls that do not participate in the connection between the electrodes of the first to third micro-LEDs 110, 120, and 130 and the electrode pads 41 and 42 of the substrate 40. In this case, among the plurality of conductive balls 75 provided in the conductive region 73, some conductive balls that are spaced apart from the electrode pads 41 and 42 of the substrate 40 do not have to directly participate in the connection between the electrodes of the first to third micro-LEDs 110, 120, and 130 and the electrode pads 41 and 42 of the substrate 40. Therefore, in some embodiments, aligning the plurality of conductive balls 75 in the plurality of grooves 210 is performed to reduce the number of conductive balls that do not participate in the connection between the electrodes of the first to third micro-LEDs 110, 120, and 130 and the electrode pads 41 and 42 of the substrate 40. Figure 4 ) and the electrode pad 41 of the substrate 40 of the display module 3.

[0080] The intervals between the plurality of conductive balls 75 may be such that at least two or three conductive balls 75 may be provided between the electrodes of the first to third micro LEDs 110, 120, and 130 and the corresponding electrode pads of the substrate 40. Therefore, the connection between the electrodes of the first to third micro LEDs 110, 120, and 130 and the corresponding electrode pads of the substrate 40 may be stably performed.

[0081] The first to third micro LEDs 110, 120, and 130 may be transferred to the substrate 40 in a state where a bonding member 70 having a conductive region 73 formed in a specific pattern is stacked on one surface 401 of the substrate 40. For example, the first micro LED 110 may be transferred from the growth substrate to the substrate 40, or may be transferred from the growth substrate to an interposer (or relay substrate) and then transferred from the interposer (or relay substrate) to the substrate 40. The second micro LED 120 and the third micro LED 130 may also be transferred to the substrate 40 in the same manner as the first micro LED.

[0082] The method of transferring the first micro LED to the third micro LEDs 110 , 120 , and 130 may be a laser transfer method, a self-assembly method, a roller transfer method, an electrostatic micro-electromechanical system (MEMS) method, a vacuum film method, or an elastic stamp method.

[0083] The first to third micro LEDs 110, 120, and 130 transferred to the substrate 40 may be mounted on the substrate 40 through a thermal press process. For example, the first electrode 111 and the second electrode 112 of the first micro LED 110 may be electrically and physically connected to a pair of electrode pads 41 and 42 of the substrate 40 through a plurality of conductive balls 75. In this case, the plurality of conductive balls 75 may be eutectically bonded to the first electrode 111 and the second electrode 112 of the first micro LED 110 and each of the pair of electrode pads 41 and 42 through high temperature heat provided in the thermal press process. Similar to the first micro LED 110, the first and second electrodes of the second and third micro LEDs 120 and 130 may be electrically and physically connected to the corresponding electrode pads through the plurality of conductive balls 75, respectively.

[0084] Figures 5 to 9 is a diagram showing a pattern of a joining member according to one example of the present disclosure.

[0085] refer to Figure 5, the pattern of the plurality of conductive balls 75 may be an island pattern in which the conductive regions 731 are independently disposed in the plurality of pixel regions 101, respectively. In this case, each conductive region 731 may be spaced apart from the conductive regions disposed in the adjacent pixel regions 101 at regular intervals. The conductive region 731 may include a region surrounding the first to third micro LEDs 110, 120, and 130, and may be located at the center of the pixel region 101. The conductive region 731 may have a substantially quadrilateral shape (e.g., a rectangular shape or a square shape), but is not limited thereto, and may be formed in a polygonal shape, such as a triangular shape or a pentagonal shape.

[0086] refer to Figure 6 , the pattern of the plurality of conductive balls 75 may be an island pattern in which the conductive regions 732 are independently disposed in the plurality of pixel regions 101. In this case, the conductive regions 732 may be approximately circular or elliptical.

[0087] refer to Figure 7 , the pattern of the plurality of conductive balls 75 may be an island pattern in which the conductive regions are independently arranged, and a plurality of patterns may be arranged in one pixel region 101. For example, the conductive region may include a first conductive region 733 corresponding to a pair of electrode pads connected to the first micro LED 110, a second conductive region 734 corresponding to a pair of electrode pads connected to the second micro LED 120, and a third conductive region 735 corresponding to a pair of electrode pads connected to the third micro LED 130. The first conductive region 733 and the second conductive region 734 may be spaced apart from each other, and the second conductive region 734 and the third conductive region 735 may be spaced apart from each other. The first to third conductive regions 733, 734, and 735 may be formed in a quadrilateral shape, but are not limited thereto, and may be formed in a polygonal shape (a triangular shape, a pentagonal shape, etc.), a circular shape, or an elliptical shape.

[0088] refer to Figure 8 , the pattern of the plurality of conductive balls 75 may be a stripe pattern in which the conductive region 736 connects adjacent pixel regions 101 in a straight line. In this case, the pattern may be formed in a horizontal direction along the arrangement direction of the first to third micro LEDs 110, 120, and 130.

[0089] refer to Fig. 9 , the plurality of conductive balls 75 disposed in the conductive region 737 may be arranged in a non-aligned state, wherein the intervals between adjacent conductive balls are uneven. The conductive region 737 may be formed in a quadrilateral shape, but is not limited thereto, and may be formed in a polygonal shape (a triangular shape, a pentagonal shape, etc.), a circular shape, or an elliptical shape.

[0090] Figures 10 to 12 is a diagram illustrating a joining member according to one example of the present disclosure.

[0091] refer to Fig.10 The bonding member 701 according to one example of the present disclosure may have a multilayer structure. For example, the bonding member 701 may include a first adhesive layer 71, a plurality of conductive balls 75 included in the first adhesive layer 71, and a second adhesive layer 77 stacked on the first adhesive layer 71. The pattern of the plurality of conductive balls 75 may be such that the conductive region 73 corresponds to Figure 3 , Figure 5 and Figures 6 to 9 The second adhesive layer 77 may be a non-conductive film (NCF) or a non-conductive paste (NCP).

[0092] refer to Fig.11 , the bonding member 702 according to one example of the present disclosure may include an adhesive layer 78 having a black base color and a plurality of conductive balls 75 included in the adhesive layer 78. The pattern of the plurality of conductive balls 75 may be such that the conductive region 73 corresponds to Figure 3 , Figure 5 and Figures 6 to 9 The pattern of one of the conductive areas shown in .

[0093] refer to Fig.12 , the bonding member 703 according to one example of the present disclosure may include an adhesive layer 71 and a plurality of conductive balls 75 included in the adhesive layer 71. The pattern of the plurality of conductive balls 75 may be such that the conductive region 73 corresponds to Figure 3 , Figure 5 and Figures 6 to 9 The plurality of conductive balls 75 may be arranged in at least two layers in the thickness direction of the adhesive layer 71 .

[0094] Therefore, even in the case where the pressure applied to the plurality of micro LEDs is insufficient due to a change or error in the thermal process conditions for connecting the plurality of micro LEDs to the substrate, the connection between the electrodes of the micro LEDs and the electrode pads of the substrate can be smoothly performed through the plurality of conductive balls 75 arranged vertically in the thickness direction of the adhesive layer 71, and thus, the yield of the display module 3 can be improved. Furthermore, even in the case where the micro LEDs are tilted due to a change in the pressure applied to the micro LEDs, the connection between the electrodes of the micro LEDs and the electrode pads of the substrate can be smoothly performed through the plurality of conductive balls 75.

[0095] Hereinafter, a method of manufacturing the bonding member 703 in which the plurality of conductive balls 75 are arranged in at least two layers in the thickness direction of the adhesive layer 71 will be described.

[0096] Fig.13is a flowchart illustrating a method of manufacturing a joined member according to one example of the present disclosure. Fig.14 is a plan view showing a molded substrate for manufacturing a joined member according to one example of the present disclosure. Fig.15 is along Fig.14 A cross-sectional view taken along line CC'. Figures 16 to 18 is a diagram illustrating a process of manufacturing a joined member according to one example of the present disclosure.

[0097] The molded substrate 200 may be manufactured by the following process, but is not limited thereto. First, a photoresist is coated on a wafer (e.g., a Si wafer or a glass wafer), and the wafer is heated. A fluoropolymer film is coated on one surface of the wafer coated with the photoresist to form a plurality of grooves 210 in the molded substrate 200. A thermosetting polymer is coated on the fluoropolymer film and then cured to form a Fig.14 The molded substrate 200 ( Fig.13 1301 in ).

[0098] refer to Fig.14 In the molded substrate 200, the plurality of conductive balls 75 may be arranged in two layers before being disposed in the adhesive layer 71. The molded substrate 200 may have a plurality of grooves 210 into which the plurality of conductive balls 75 are inserted. The pattern of the plurality of grooves 210 may determine the pattern of the plurality of conductive balls 75 disposed in the bonding member 703 (see Fig.12 ).

[0099] refer to Fig.15 , the plurality of grooves 210 may have a predetermined depth D so that the plurality of conductive balls 75 are arranged in two layers. In this case, the depth D of the grooves 210 may be at least twice the diameter of the conductive ball 75. Therefore, in each of the plurality of grooves 210, at least two conductive balls 75 may be inserted in the vertical direction and vertically stacked. The diameter (or width) of each of the plurality of grooves 210 may be equal to or greater than the diameter of the conductive ball 75.

[0100] The mold substrate 200 may be formed of a thermosetting polymer (eg, polydimethylsiloxane (PDMS)) that has elasticity and can easily form a plurality of fine grooves 210 .

[0101] In the molded substrate 200 , an optically transparent resin (e.g., an optically clear adhesive (OCA), an optically clear resin (OCR), ethylene vinyl acetate copolymer (EVA), or polyolefin (POE)) or an adhesive may be applied on the plurality of grooves 210 to enable the plurality of conductive balls 75 to be easily inserted into the plurality of grooves 210 .

[0102] refer to Fig.16, a plurality of conductive balls 75 are scattered on the mold substrate 200 and then inserted into a plurality of grooves 210 of the mold substrate 200. Therefore, the plurality of conductive balls 75 can be aligned in the plurality of grooves 210 ( Fig.13 1302 in). In this case, surface treatment may be performed to prevent the plurality of conductive balls 75 from adhering to the surface of the molded substrate 200 other than the plurality of grooves 210. The surface treatment may be performed in the process of manufacturing the molded substrate 200. For example, the surface of the molded substrate 200 not having the plurality of grooves 210 may be plasma-treated to form fine concavoconvexities, or may be hydrophobically treated. In some embodiments, the molded substrate 200 is a relay substrate, the plurality of grooves 210 are in the relay substrate, and the plurality of grooves 210 are treated with plasma to prevent the plurality of conductive balls 75 from adhering to the relay substrate.

[0103] refer to Fig.17 , the molded substrate 200 with the plurality of conductive balls 75 inserted into the plurality of grooves 210 is placed on the adhesive layer 71. The plurality of grooves 210 may be arranged to face the adhesive layer 71 ( Fig.13 1303 in ).

[0104] In this state, the mold substrate 200 is pressed toward the adhesive layer 71 at a predetermined pressure. Therefore, as the mold substrate 200 is compressed due to its own elasticity, the plurality of conductive balls 75 inserted into the plurality of grooves 210 may be introduced into the adhesive layer 71 ( Fig.13 1304 in ).

[0105] The adhesive layer 71 may be heated to a predetermined temperature so that the plurality of conductive balls 75 are smoothly introduced into the adhesive layer 71 based on the mold substrate 200 being pressed.

[0106] The adhesive layer 71 may be a non-conductive film (NCF) and may contain a flux to enable good bonding between the conductive balls 75 and the electrodes of the micro LED.

[0107] refer to Fig.18 , a bonding member 703 can be manufactured by the above process, wherein a plurality of conductive balls 75 are arranged in two layers in the adhesive layer 71. In this case, the pattern of the plurality of conductive balls 75 can be one in which the conductive area 73 corresponds to Figure 3 , Figure 5 and Figures 6 to 9 The pattern of one of the conductive areas shown in .

[0108] Fig.19 is a cross-sectional view showing a molded substrate for manufacturing a joined member according to one example of the present disclosure. Fig. 20 is a diagram showing an example of aligning a plurality of conductive balls in a plurality of grooves of a mold substrate by using vacuum adsorption.

[0109] refer to Fig.19 , a plurality of holes 230 communicating with the plurality of grooves 210 may be formed on another surface of the molded substrate 200. The diameter of the plurality of holes 230 may be smaller than the diameter of the plurality of grooves 210. With respect to the size of the plurality of grooves 210, the plurality of conductive balls 75 in the plurality of grooves 210 are configured to support electrical connection of pads 112 of inorganic light emitting diodes disposed on the substrate 40 of the display module 3 at ultra-fine pitches. The display module 3 includes a display driver IC 7 for controlling the substrate 40, and in some embodiments, the manufacturing process includes mounting the inorganic light emitting diodes (pixels 100) on the substrate 40 to be controlled by the display driver IC 7 when in use. In some embodiments, the inorganic light emitting diodes (pixels 100) are in the form of micro LED chips, and the substrate 40 of the display module 3 is an anisotropic conductive film (ACF). In some embodiments, the method includes mounting the micro LED chips on the substrate using the ACF and a thermocompression bonding process.

[0110] refer to Fig. 20 , the plurality of conductive balls 75 may be aligned in the plurality of grooves 210 by a vacuum adsorption method using the mold substrate 200. For example, vacuum pressure may be formed in the plurality of holes 230 by driving the vacuum source 270 in a state where the suction cup 250 is in close contact with the other surface of the mold substrate 200. In this case, vacuum pressure may also be formed in the plurality of grooves 210 respectively connected to the plurality of holes 230. The vacuum source 270 may be a vacuum motor or a vacuum pump.

[0111] The plurality of conductive balls 75 dispersed on the mold substrate 200 may be sucked into the plurality of grooves 210 by the vacuum pressure formed in the plurality of grooves 210. Therefore, the plurality of conductive balls 75 may be aligned in the plurality of grooves 210 by the vacuum adsorption method.

[0112] The suction cup 250 may have a first channel formed therein and connected to the vacuum source 270, and a plurality of second channels respectively connected to the plurality of holes 230 of the mold substrate 200. Since the plurality of second channels are connected to the first channel, vacuum pressure may also be formed in the plurality of holes 230 based on the vacuum pressure formed in the first channel.

[0113] The vacuum source 270 may be continuously driven until the stacking of the molded substrate 200 on the adhesive layer 71 is completed. Therefore, during the stacking of the molded substrate 200 on the adhesive layer 71, the plurality of conductive balls 75 may be prevented from being detached from the plurality of grooves 210 of the molded substrate 200. Therefore, after the stacking of the molded substrate 200 on the adhesive layer 71 is completed, the suction cup 250 may be separated from the molded substrate 200, and then the molded substrate 200 may be pressed against the adhesive layer 71.

[0114] In the above, the present disclosure has been described as an illustrative method. It should be understood that the terms used herein are provided to describe the present disclosure rather than to limit the present disclosure. Various modifications and changes can be made to the present disclosure based on the above. Therefore, unless otherwise mentioned, the present disclosure can be freely practiced without departing from the scope of the claims.

Claims

1. A display module, comprising: a substrate divided into a plurality of pixel regions and comprising a plurality of electrode pads disposed in the plurality of pixel regions; a bonding member including an adhesive layer stacked on one surface of the substrate and a plurality of conductive balls disposed in the adhesive layer; as well as a plurality of light emitting diodes including electrodes connected to the plurality of electrode pads through the plurality of conductive balls, The plurality of conductive balls are patterned into conductive areas corresponding to the plurality of electrode pads.

2. The display module according to claim 1, wherein: The pattern of the plurality of conductive balls is a stripe pattern, the conductive region is disposed in a plurality of pixel regions adjacent to each other, and the conductive region is configured to connect the plurality of electrode pads in a straight line.

3. The display module according to claim 1, wherein: The pattern of the plurality of conductive balls is arranged in an island pattern in which the conductive regions are independently arranged in the plurality of pixel regions, respectively.

4. The display module according to claim 3, wherein: The pixels arranged in the plurality of pixel regions include a plurality of sub-pixels, Each of the conductive regions provided in each of the plurality of pixel regions includes a plurality of sub-conductive regions corresponding to the plurality of sub-pixels, and The plurality of sub-conductive regions are spaced apart from each other.

5. The display module according to claim 1, wherein: The plurality of conductive balls are arranged in at least two layers in a thickness direction of the adhesive layer.

6. A bonding member for connecting an electrode of a light emitting diode and an electrode pad of a display substrate, the bonding member comprising: Adhesive layer; as well as A plurality of conductive balls are disposed in the adhesive layer, The plurality of conductive balls are patterned as a conductive region in a portion of the entire region of the bonding member.

7. The joining member according to claim 6, wherein: The pattern of the plurality of conductive balls is arranged in a stripe pattern in which the conductive regions form a plurality of straight lines.

8. The joining member according to claim 6, wherein: The pattern of the plurality of conductive balls is an island pattern in which the conductive regions are spaced apart from each other.

9. The joined member according to claim 6, further comprising an additional adhesive layer stacked on the adhesive layer.

10. The joining member according to claim 6, wherein: The adhesive layer has a black base color.

11. A method for manufacturing a joint member, the method comprising: forming a molded substrate having a plurality of grooves patterned in one surface thereof; aligning a plurality of conductive balls in the plurality of grooves; disposing the mold substrate to correspond to the adhesive layer so that the plurality of conductive balls face the adhesive layer; as well as The plurality of conductive balls are disposed in the adhesive layer by pressing the mold substrate against the adhesive layer.

12. The manufacturing method according to claim 11, wherein: In a thickness direction of the mold substrate, depths of the plurality of grooves are at least twice as large as diameters of the plurality of conductive balls.

13. The manufacturing method according to claim 11, wherein: A surface treatment for preventing the plurality of conductive balls from being attached is performed on an area of ​​the one surface of the mold substrate where the plurality of grooves are not formed.

14. The manufacturing method according to claim 11, wherein: An adhesive is applied over the plurality of recesses prior to aligning the plurality of conductive balls in the plurality of recesses.

15. The manufacturing method according to claim 11, wherein: forming a plurality of holes communicating with the plurality of grooves on the other surface of the mold substrate, and When the plurality of conductive balls are aligned in the plurality of grooves, negative pressure is formed in the plurality of grooves through the plurality of holes to insert the plurality of conductive balls into the plurality of grooves.

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