Display device using light emitting device and method of manufacturing the same

Abstract

The invention can be applied to the related technical field of display devices, and relates to a display device using a micro LED and a manufacturing method thereof. The present invention, as a display device using a light emitting device, may comprise: a wiring substrate; electrode pads which define a unit sub-pixel region and are arranged on the wiring substrate; a light emitting device having a first type electrode disposed on the electrode pad; a connection portion including a plurality of conductive particles electrically connecting a first type electrode of the light emitting device and the electrode pad; the first slurry layer is positioned on the light-emitting device and the connecting part; and a second slurry layer on the first slurry layer.

Description

Technical Field

[0001] The present invention can be applied to the technical field related to display devices, and relates to a display device using micro LEDs (Light Emitting Diodes) and a manufacturing method thereof. Background Art

[0002] In recent years, in the field of display technology, display devices with excellent characteristics such as thinness and flexibility have been developed. In contrast, the main commercialized display representatives are liquid crystal displays (LCD) and organic light emitting diodes (OLED).

[0003] However, in the case of LCD, there are problems of slow response time and difficulty in achieving flexibility, and in the case of OLED, there are problems of short lifespan and poor mass production yield.

[0004] On the other hand, a light emitting diode (LED) is a well-known semiconductor light emitting device that converts electric current into light. Since the commercialization of red LED using GaAsP compound semiconductor in 1962, it has been used together with GaP:N series green LED as a light source for displaying images in electronic devices represented by information and communication equipment. Therefore, a solution to the above-mentioned problem can be proposed by realizing a display using a semiconductor light emitting device. Compared with a filament-based light emitting device, the semiconductor light emitting device has various advantages such as long life, low power consumption, excellent initial driving characteristics, and strong vibration resistance.

[0005] In recent years, the size of such semiconductor light emitting devices has been reduced to tens of micrometers. Therefore, in the case of realizing a display device using such small-sized semiconductor light emitting devices, a large number of semiconductor light emitting devices need to be assembled on a wiring substrate of the display device.

[0006] However, in the process of assembling such light emitting devices, there is a problem that it is difficult to accurately position a large number of semiconductor light emitting devices at target positions on a wiring substrate. This problem becomes more serious with the development of high-resolution displays.

[0007] In this assembly process, the light emitting device may be directly transferred to the wiring electrode, or may be transferred using a donor substrate. At this time, a conductive ball or a conductive film may be used between the electrode of the light emitting device and the wiring electrode.

[0008] A problem with Anisotropic Conductive Film (ACF) bonding involving conductive balls is that there is a probability of electrical connection of pads of small components due to the randomness of the positions of the conductive balls.

[0009] When bonding using a polymer resin forming an adhesive in the form of cotton, the pressure required for bonding is high due to the flow and resistance of the resin due to the contact area.

[0010] In order to improve the adhesive margin, attempts are being made to solve the problem by a partial resin coating method using an electrically conductive paste (ACP) in which conductive balls are mixed in a liquid state and patterned by a printing method.

[0011] With this solution, ACP has a higher degree of bonding freedom compared to ACF, but there is a problem that it cannot be applied to small components due to the randomness of the positions of the conductive balls.

[0012] On the other hand, a method of using a non-conductive paste (NCP) as a bonding material (adhesive part) is being used by developing a method of selectively patterning conductive balls on N and P electrodes of a light-emitting device on a chip on wafer (COW).

[0013] However, in such thermal compression bonding, the area that can be bonded is limited due to the flatness and pressure of the bonding head.

[0014] In addition, due to the flatness and levelness of the bond head, excessive pressure or weak pressure may be applied at specific locations.

[0015] When bonding is performed using conductive balls, a local portion where a weak bonding pressure is applied may cause the conductive ball to return to its original position at the moment the pressure is removed after bonding, resulting in a phenomenon in which the contact through the conductive ball is separated.

[0016] On the contrary, if excessive pressure is applied, the conductive ball will not generate any restoring force even if it changes to a Pac-man shape to the extent that the restoring force is lost, which may cause the contact to separate.

[0017] On the other hand, when connecting the electrodes of the light-emitting device and the wiring electrodes, a reflow electrical connection method using heat treatment is used. However, as the display area becomes larger, it is difficult to achieve electrical connection between a single micro-LED element and a wiring substrate by heat pressing due to problems in the implementation of bonding equipment (pressure increases in proportion to the flatness and area of ​​the head).

[0018] For example, there is a problem that it is difficult to apply a method of printing solder to an electrode pad pattern of a micro LED having a small size of a 10 μm unit.

[0019] When solder is manufactured using electroplating or deposition methods, it is difficult to achieve electrical connection of micro LEDs due to cost issues and limitations on surface materials used to address surface wettability.

[0020] That is, during the solder reflow heat treatment, the solder may diffuse, resulting in an electrical short circuit between the N and P electrode pads of the light emitting device.

[0021] Therefore, a solution that can solve this problem is needed. Summary of the invention

[0022] Problems to be solved by the invention

[0023] The technical problem to be solved by the present invention is to provide a display device using a light-emitting device and a manufacturing method thereof, which can realize electrical connection between the light-emitting device having a micrometer or millimeter size and a wiring electrode under more relaxed bonding conditions.

[0024] In addition, a display device using a light-emitting device and a method for manufacturing the same are provided, which are capable of achieving stable bonding of the light-emitting device even when there is variation in the height (size) of the light-emitting device.

[0025] In addition, a display device using light-emitting devices and a method for manufacturing the same are provided, which are capable of achieving stable bonding of the light-emitting devices when the interval between the light-emitting devices is narrow.

[0026] Technical solutions to the problem

[0027] As a first viewpoint for achieving the above-mentioned purpose, the present invention, as a display device utilizing a light-emitting device, may include: a wiring substrate; an electrode pad, which defines a unit sub-pixel area and is arranged on the wiring substrate; a light-emitting device, on which a first-type electrode is configured; a connecting portion, including a plurality of conductive particles that electrically connect the first-type electrode of the light-emitting device and the electrode pad; a first slurry layer, which is located above the light-emitting device and the connecting portion; and a second slurry layer, which is located above the first slurry layer.

[0028] As an exemplary embodiment, at least one of the first slurry layer and the second slurry layer may be provided in units of one pixel area.

[0029] As an exemplary embodiment, the height of the first paste layer may be the same as the top surface of the light emitting device.

[0030] As an exemplary embodiment, the maximum height of the first paste layer may correspond to the highest height of the light emitting device.

[0031] As an exemplary embodiment, the display device may further include a covering layer located on the second paste layer.

[0032] As an exemplary embodiment, the interface between the first paste layer and the second paste layer may connect the adjacent light emitting devices.

[0033] As an exemplary embodiment, an interface between the first paste layer and the second paste layer may have a hang structure between the adjacent light emitting devices.

[0034] As an exemplary embodiment, the height of the overhanging structure may be greater than the height deviation of the adjacent light emitting devices.

[0035] As an exemplary embodiment, the height of the overhanging structure may be more than half of the height of the light emitting device.

[0036] As an exemplary embodiment, the second slurry layer may include at least one of reflective particles and black particles.

[0037] As an exemplary embodiment, the second paste layer may be used to prevent the light emitting device from being separated from the electrode pad.

[0038] As a second viewpoint for achieving the above-mentioned purpose, the present invention, as a method for manufacturing a display device using a light-emitting device, may include: a step of applying a first slurry layer containing conductive particles on a wiring substrate on which electrode pads are arranged; a step of configuring the light-emitting device on the electrode pads; a step of applying a second slurry layer on the first slurry layer; and a step of performing pressing to electrically connect the light-emitting device to the electrode pads.

[0039] As an exemplary embodiment, the step of applying the first slurry layer including the conductive particles may include: transferring the conductive particles to the electrode pad; and applying the first slurry layer on the electrode pad to which the conductive particles are transferred.

[0040] As an exemplary embodiment, the first slurry layer and the second slurry layer may have different curing speeds from each other.

[0041] As an exemplary embodiment, in the pressing step, the first bonding head may be located on the second slurry layer and the second bonding head may be located under the power distribution substrate, and the first bonding head and the second bonding head may be pressed toward each other.

[0042] As an exemplary embodiment, the pressing step may be performed while heating.

[0043] As an exemplary embodiment, at least one of the first slurry layer and the second slurry layer may be coated in units of one pixel area.

[0044] As an exemplary embodiment, the deviation of the height of the light emitting device may be 10 to 20 μm.

[0045] As an exemplary embodiment, the interval between adjacent electrode pads may be 35 μm or less.

[0046] As an exemplary embodiment, the second paste layer may be used to prevent the light emitting device from being separated from the electrode pad due to the elasticity of the conductive particles after the pressing step.

[0047] Effects of the Invention

[0048] According to an embodiment of the present invention, the following effects are achieved.

[0049] First, according to an embodiment of the present invention, it is possible to achieve electrical connection between a light-emitting device having a micron or millimeter size and a wiring electrode with a looser bonding condition by expanding the electrical contact area between conductive nanoparticles and conductive microparticles (conductive balls) and preventing excessive pressing.

[0050] In addition, according to the embodiments of the present invention, stable bonding of the light emitting device can be achieved even when there is a deviation in the height (size) of the light emitting device.

[0051] In addition, according to the embodiments of the present invention, stable bonding of light emitting devices can be achieved when the interval between the light emitting devices is narrow.

[0052] Furthermore, according to another embodiment of the present invention, there are additional technical effects not mentioned here, which can be understood by those skilled in the art through the overall purpose of the specification and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 FIG. 1 is a cross-sectional view showing a unit pixel of a display device using a light emitting device according to an embodiment of the present invention.

[0054] Figure 2 FIG. 4 is a cross-sectional view showing a unit pixel of a display device using a light emitting device according to another embodiment of the present invention.

[0055] Figures 3 to 6 1 is a schematic cross-sectional view showing steps of manufacturing a display device using a light-emitting device according to an embodiment of the present invention.

[0056] Figure 7 FIG. 1 is a flowchart showing steps of manufacturing a display device using a light emitting device according to an embodiment of the present invention.

[0057] Figure 8 FIG. 1 is a diagram showing an example of a light emitting device that can be applied to a display device using the light emitting device according to an embodiment of the present invention.

[0058] Fig. 9 is a photograph showing a cross section of a display device manufactured by a general manufacturing process as a comparative example.

[0059] Fig.10 This is a photograph showing a cross section of a display device manufactured according to one embodiment of the present invention.

[0060] Fig.11 : is a photograph showing the screen state of a display device of a comparative example.

[0061] Fig.12 1 is a photograph showing the screen state of a display device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0062] Hereinafter, the embodiments disclosed in this specification will be described in detail with reference to the accompanying drawings. Regardless of the figure numbers, the same or similar constituent elements are given the same figure numbers, and repeated descriptions thereof are omitted. The suffixes "module" and "unit" of the constituent elements used in the following description are given or mixed for the convenience of writing the specification, and they themselves do not have mutually distinguishable meanings or functions. In addition, when describing the embodiments disclosed in this specification, when it is determined that the specific description of the relevant known technology may make the gist of the embodiments disclosed in this specification unclear, its detailed description will be omitted. In addition, it should be noted that the drawings are only used to make the embodiments disclosed in this specification easy to understand, and the technical ideas disclosed in this specification are not limited by the drawings.

[0063] Furthermore, although the drawings are described separately for the convenience of explanation, those skilled in the art may implement other embodiments by combining at least two or more drawings, which also fall within the scope of the present invention.

[0064] In addition, it should be understood that when an element such as a layer, a region or a substrate is described as being “on” different constituent elements, it means that it is directly on other elements or intervening elements may exist between the two elements.

[0065] In addition, the semiconductor light-emitting devices involved in this specification include concepts such as LEDs and micro LEDs, and they can be used interchangeably.

[0066] Figure 1 FIG. 1 is a cross-sectional view showing a unit pixel of a display device using a light emitting device according to an embodiment of the present invention.

[0067] Reference Figure 1 , a display device 10 is shown in which light-emitting devices 310, 320, and 330 forming a unit pixel are arranged on a wiring substrate 100. As an example, the light-emitting devices 310, 320, and 330 forming the unit pixel may include a first light-emitting device 310, a second light-emitting device 320, and a third light-emitting device 330. As an example, the first light-emitting device 310 may be a red light-emitting device 310 emitting red light, the second light-emitting device 320 may be a green light-emitting device 320 emitting green light, and the third light-emitting device 330 may be a blue light-emitting device 330 emitting blue light.

[0068] The wiring substrate 100 may be divided into a plurality of wiring electrodes (not shown) on the substrate 110. Here, the wiring electrodes may include data electrodes (pixel electrodes) and scan electrodes (common electrodes).

[0069] Here, three light emitting devices 310, 320, and 330 may form a unit pixel. These unit pixels may be repeatedly arranged on the wiring substrate 100. At this time, one light emitting device may form a unit sub-pixel. Figure 1 The light emitting devices 310 , 320 , and 330 are shown in a state where they are mounted by flip chip bonding.

[0070] Electrode pads 120 (121, 122, 123) connected to wiring electrodes may be provided on the substrate 110. Here, the shapes of the electrode pads 120 (121, 122, 123) may be simplified and illustrated. The electrodes 312, 313 (refer to Figure 8 ) can be electrically connected to such electrode pads 121, 122, 123 through conductive particles 400, 410. In addition, the interval between the electrode pads 120 (121, 122, 123) can be 35μm or less. That is, the interval between adjacent electrode pads 121, 122, 123 can be 35μm or less. As described above, in the case where the interval between adjacent electrode pads 121, 122, 123 is 35μm or less, the electrical connection of the light-emitting devices 310, 320, 330 such as solder reflow may not be appropriate. In this case, a structure of a connecting portion 410 as described below and a multi-layer structure of paste layers 200, 210 covering the connecting portion 410 of the structure can be formed.

[0071] Here, the conductive particles 400, 410 may have a size in micrometer (μm) units. Therefore, the conductive particles 400, 410 may be referred to as micro conductive particles or conductive balls. Such conductive particles 400, 410 may form an electrical connection between the electrode pads 121, 122, 123 and the light emitting devices 310, 320, 330. As an example, the conductive particles 400 are coated between the electrode pads 121, 122, 123 and the light emitting devices 310, 320, 330 before forming the connection, and then deformed and formed into the connection 410 by the bonding process of the electrode pads 121, 122, 123 and the light emitting devices 310, 320, 330. That is, the conductive particles 400 may become deformed conductive particles 410 by the bonding process of the electrode pads 121, 122, 123 and the light emitting devices 310, 320, 330.

[0072] As described above, light emitting devices 310 , 320 , 330 may be disposed on the electrode pads 121 , 122 , 123 , and the light emitting devices 310 , 320 , 330 may be disposed with at least one of the electrodes 312 , 313 (as an example, the first type electrode 312 ).

[0073] Although not shown, the electrode pads 120 arranged on the wiring substrate 100 may be connected to a TFT layer provided with a thin film transistor (TFT). The data electrode (pixel electrode) may be connected to such a TFT layer. Detailed description of this is omitted.

[0074] As described above, a connection portion including a plurality of conductive particles 410 that electrically connects the first type electrode 312 of the light emitting device 310, 320, 330 and the electrode pads 121, 122, 123 may be provided. Hereinafter, the conductive particles 410 and the connection portion 410 located between the electrode pads 121, 122, 123 and the light emitting device 310, 320, 330 are described using the same reference numerals.

[0075] In addition, a first paste layer 200 may be disposed on the light emitting devices 310, 320, 330 and the connection portion 410. A second paste layer 210 may be disposed on the first paste layer 200.

[0076] As an exemplary embodiment, at least one of the first slurry layer 20 and the second slurry layer 210 may be provided in units of one pixel region. That is, at least one of the first slurry layer 200 and the second slurry layer 210 may be provided in a manner of covering three light emitting devices 310, 320, 330 forming one pixel.

[0077] Figure 1An example is shown in which the first slurry layer 200 is arranged in a manner of covering three light-emitting devices 310, 320, and 330 forming one pixel, and the second slurry layer 210 is located on the first slurry layer 200 forming one region. However, according to an embodiment, the first slurry layer 200 may be arranged in a manner of covering a plurality of pixel regions. In addition, the second slurry layer 210 may also be arranged in a manner of covering a plurality of first slurry layers 200 forming a plurality of regions.

[0078] As an exemplary embodiment, the height of the first paste layer 200 and the top surface of the light emitting devices 310, 320, 330 may be substantially the same. Here, "substantially" may mean that the electrical connection (as an example, hot pressing) process between the light emitting devices 310, 320, 330 and the electrode pads 121, 122, 123 includes an acceptable error.

[0079] In addition, as an example, the maximum height of the first slurry layer 200 may correspond to the highest height of the light emitting devices 310, 320, and 330. In other words, such light emitting devices 310, 320, and 330 may have a height deviation. When such a height deviation is taken into account, the maximum height of the first slurry layer 200 may correspond to the light emitting device having the highest height among the light emitting devices 310, 320, and 330 ( Figure 1 The height of the third light emitting device 330 in the case corresponds to the height of the third light emitting device 330.

[0080] As described above, since the first slurry layer 200 and the second slurry layer 210 are formed of separate layers, an interface may be provided between the first slurry layer 200 and the second slurry layer 210. That is, the first slurry layer 200 and the second slurry layer 210 may be distinguished from each other.

[0081] In addition, the interface between the first slurry layer 200 and the second slurry layer 210 may connect adjacent light emitting devices to each other. That is, the interface between the first slurry layer 200 and the second slurry layer 210 may connect the top surfaces of the light emitting devices 310, 320, and 330 to each other.

[0082] Therefore, the interface between the first paste layer 200 and the second paste layer 210 may have a structure of hanging between adjacent light emitting devices.

[0083] Reference Figure 1A first interface 201 may be formed between the first light emitting device 310 and the second light emitting device 320. In addition, a second interface 202 may be formed between the second light emitting device 320 and the third light emitting device 330. At this time, at least one of the first interface 201 and the second interface 202 may have an overhang structure. That is, at least one of the first interface 201 and the second interface 202 may be formed to continuously connect the top surfaces of adjacent light emitting devices to each other.

[0084] In addition, the height of the overhanging structure may be greater than the height deviation of adjacent light emitting devices 310 , 320 , 330 .

[0085] In addition, as an exemplary embodiment, the height of the overhanging structure may be more than half of the height of the light emitting devices 310 , 320 , 330 .

[0086] As described above, the first slurry layer 200 can be formed by connecting the top surfaces of the light-emitting devices 310, 320, and 330 forming one pixel to each other. As an example, the third interface 203 located outside the first light-emitting device 310 can be formed by connecting the top surface of the substrate 110 and the top surface of the first light-emitting device 310. In addition, the fourth interface 204 located outside the third light-emitting device 330 can be formed by connecting the top surface of the substrate 110 and the top surface of the third light-emitting device 330.

[0087] As described above, the light emitting devices 310, 320, 330 may have a height deviation. Therefore, the height of the third interface 203 and the height of the fourth interface 204 may be different from each other.

[0088] For example, the first light emitting device 310 may have a first height h1, the second light emitting device 320 may have a second height h2, and the third light emitting device 330 may have a third height h3. The heights of the light emitting devices 310, 320, 330 may have a deviation of 10 to 20 μm.

[0089] The first paste layer 200 as described above can stably protect the connection portion 410 between the light emitting devices 310, 320, 330 and the electrode pads 121, 122, 123. In addition, the first paste layer 200 can wrap the connection portion 410 between the light emitting devices 310, 320, 330 and the electrode pads 121, 122, 123 having height deviations and form a stable connection structure.

[0090] The second paste layer 210 may be used to prevent the light emitting devices 310, 320, 330 from being separated from the electrode pads 121, 122, 123 during the bonding process of the light emitting devices 310, 320, 330 and the electrode pads 121, 122, 123. This will be described in detail later.

[0091] The first slurry layer 200 and the second slurry layer 210 may include materials different from each other. As an example, the first slurry layer 200 and the second slurry layer 210 may be formed of materials different from each other. As an example, the first slurry layer 200 and the second slurry layer 210 may be formed of materials having different curing speeds from each other.

[0092] Reference Figure 1 , a cover layer 500 may be disposed on the second slurry layer 210. Such a cover layer 500 may protect the second slurry layer 210. Depending on the situation, the cover layer 500 may flatten the second slurry layer 210. However, such a cover layer 500 may also be omitted. In addition, an additional cap may also be disposed on the cover layer 500.

[0093] Figure 2 is a cross-sectional view showing a unit pixel of a display device using a light emitting device according to another embodiment of the present invention.

[0094] Reference Figure 2 , a display device 10 is shown in which light emitting devices 310, 320, 330 forming a unit pixel are arranged on a wiring substrate 100. As an example, the light emitting devices 310, 320, 330 forming a unit pixel may include a first light emitting device 310, a second light emitting device 320, and a third light emitting device 330.

[0095] The wiring substrate 100 may include a substrate 110, on which electrode pads 120 (121, 122, 123) connected to wiring electrodes may be provided. Here, the shapes of the electrode pads 120 (121, 122, 123) may be simplified and illustrated. The electrodes 312, 313 (refer to Figure 8 ) can be electrically connected to such electrode pads 121, 122, 123 through conductive particles 400, 410.

[0096] Such conductive particles 400, 410 may form electrical connections between electrode pads 121, 122, 123 and light emitting devices 310, 320, 330. Conductive particles 400 may become deformed conductive particles 410 through the bonding process of electrode pads 121, 122, 123 and light emitting devices 310, 320, 330.

[0097] In addition, a first paste layer 200 may be disposed on the light emitting devices 310, 320, 330 and the connection portion 410. A second paste layer 210 may be disposed on the first paste layer 200.

[0098] The second slurry layer 210 may include functional particles. As an example, the second slurry layer 210 may include reflective particles 211, which may reflect light emitted from the light emitting devices 310, 320, and 330 to radiate to the outside. As another example, the second slurry layer 210 may include black particles 212 that can improve contrast. As described above, the second slurry layer 210 may include at least one of the reflective particles 211 and the black particles 212.

[0099] In addition, this embodiment can be compared with the above reference Figure 1 The embodiments described are the same, so repeated descriptions are omitted.

[0100] Figures 3 to 6 1 is a schematic cross-sectional view showing the manufacturing steps of a display device using a light-emitting device according to an embodiment of the present invention. Figure 7 FIG. 1 is a flowchart showing steps of manufacturing a display device using a light emitting device according to an embodiment of the present invention.

[0101] The following, with Figure 7 Refer to Figures 3 to 6 , a manufacturing process of a display device using a light-emitting device according to an embodiment of the present invention is described in detail.

[0102] First, refer to Figure 3 A first slurry layer 200 including conductive particles 400 may be applied on a wiring substrate 100 having electrode pads 120 ( 121 , 122 , 123 ) arranged on one side of a substrate 110 ( S10 , S20 ).

[0103] The conductive particles 400 may be uniformly distributed in the first paste layer 200. Thus, the plurality of conductive particles 400 may be located on the electrode pads 121, 122, 123. In addition, the conductive particles 400 may also be located in a portion other than the electrode pads 121, 122, 123.

[0104] As described above, the step S10 of coating the conductive particles 400 and the step S20 of printing the first paste layer 200 may be simultaneously performed by printing the first paste layer 200 including the conductive particles 400 .

[0105] However, according to an embodiment, after step S10 of coating the conductive particles 400 on the electrode pads 121 , 122 , 123 , the first paste layer 200 may be printed to cover the electrode pads 121 , 122 , 123 coated with the conductive particles 400 ( S20 ).

[0106] That is, as an exemplary embodiment, the step of applying the first slurry layer 200 including the conductive particles 400 may include: the step of transferring the conductive particles 400 to the electrode pads 121, 122, 123; and the step of applying the first slurry layer 200 on the electrode pads 121, 122, 123 to which the conductive particles 400 are transferred.

[0107] In other words, anisotropic conductive paste (ACP) which is a liquid resin in which conductive particles 400 are dispersed, or immovable conductive paste (ICP) which is a liquid resin applied only to electrodes after conductive balls are formed, may be printed on electrode pads 121, 122, 123 of wiring substrate 100. In addition, according to the embodiment, other materials that can be electrically connected to electrodes can be used in addition to conductive particles 400.

[0108] As described above, at least three electrode pads 121, 122, 123 may correspond to a light emitting device defining one pixel.

[0109] In addition, the interval between the electrode pads 120 (121, 122, 123) may be 35 μm or less. That is, the interval between adjacent electrode pads 121, 122, 123 may be 35 μm or less. In this case, a connection portion 410 for electrical connection of the light-emitting devices 310, 320, 330 and a multi-layered paste layer 200, 210 covering the connection portion 410 may be formed.

[0110] Here, the conductive particles 400 and 410 may have a size in micrometers (μm). Therefore, the conductive particles 400 and 410 may also be referred to as micro conductive particles or conductive balls.

[0111] The first slurry layer 200 may be provided in a manner of covering at least three electrode pads 121, 122, 123 corresponding to one pixel region. As an example, the first slurry layer 200 may be provided in a manner of partially covering at least three electrode pads 121, 122, 123 corresponding to one pixel region. However, according to an embodiment, the first slurry layer 200 may also be provided in a manner of covering a plurality of pixel regions.

[0112] Next, refer to Figure 4 , the light emitting devices 310, 320, 330 may be disposed on the electrode pad 120. As an example, the corresponding light emitting devices 310, 320, 330 may be disposed on three electrode pads 121, 122, 123.

[0113] As described above, the light emitting devices 310, 320, and 330 may have a height deviation. For example, the first light emitting device 310 may have a first height h1 (refer to Figure 1 ), the second light emitting device 320 may have a second height h2 (refer to Figure 1 ), the third light emitting device 330 may have a third height h3 (refer to Figure 1 The height of the light emitting devices 310 , 320 , and 330 may vary by 10 to 20 μm.

[0114] Afterwards, refer to Figure 5 The second paste layer 210 may be applied (printed) in a manner to cover the light emitting devices 310 , 320 , 330 ( S30 ). The second paste layer 210 may be formed to cover the first paste layer 200 together with the light emitting devices 310 , 320 , 330 .

[0115] like Figure 5 As shown, the thickness of the coated second slurry layer 210 may be thicker than the first slurry layer 200 .

[0116] As described above, the first slurry layer 200 and the second slurry layer 210 may have different physical properties. For example, the first slurry layer 200 and the second slurry layer 210 may have different physical properties such as viscosity, curing speed, or hardness after curing.

[0117] Figure 5 An example is shown in which the second slurry layer 210 is located on the first slurry layer 200 forming one region. However, according to an embodiment, the first slurry layer 200 may be arranged in a manner covering a plurality of pixel regions. In addition, the second slurry layer 210 may also be arranged in a manner covering a plurality of first slurry layers 200 forming a plurality of regions.

[0118] Next, refer to Figure 6 , a pressing (bonding) step S40 may be performed to electrically connect the light emitting devices 310 , 320 , 330 to the electrode pads 121 , 122 , 123 .

[0119] In the pressing step S40 , the first bond head 610 may be located on the second paste layer 210 and the second bond head 600 may be located under the wiring substrate 100 , and the first bond head 610 and the second bond head 600 may be pressed toward each other.

[0120] As an exemplary embodiment, the pressing step S40 may be performed while heating. That is, in the pressing process (S40), the light emitting devices 310, 320, 330 and the electrode pads 121, 122, 123 may be pressed toward each other while heating.

[0121] In this process, the second paste layer 210 can prevent the light emitting devices 310 , 320 , 330 from being separated from the electrode pads 121 , 122 , 123 due to the elasticity of the conductive particles 400 after the lamination step S40 .

[0122] Through the pressing process S40 , the light emitting devices 310 , 320 , and 330 can be stably electrically connected (bonded) on the electrode pads 121 , 122 , and 123 through the conductive particles 410 .

[0123] In this state, if the cover layer 500 is formed on the second slurry layer 210, the following Figure 1 or Figure 2 Status shown.

[0124] Through this process, a plurality of light emitting devices 310 , 320 , and 330 having thickness (height) deviations can be stably electrically connected (bonded) on the electrode pads 121 , 122 , and 123 .

[0125] That is, even if the plurality of light emitting devices 310 , 320 , and 330 have thickness (height) variations, they can be electrically connected to the electrode pads 121 , 122 , and 123 .

[0126] In order to prevent the positions of the light emitting devices 310 , 320 , 330 from shifting during the transfer process, the printing thickness of the first paste layer 200 as described above may be smaller than the thickness of the light emitting devices 310 , 320 , 330 .

[0127] In order to improve the mass production rate, at least three light emitting devices 310, 320, 330 forming one RGB pixel may be mounted on a single printed pattern. Therefore, planarization of the portion of the printed pattern where the light emitting devices 310, 320, 330 are located may be required. However, when the pitch between the light emitting devices 310, 320, 330 becomes narrower or the size of the light emitting devices 310, 320, 330 becomes smaller, the larger the pattern size itself is, the more limited it is.

[0128] Therefore, the situation that the printing thickness of the first paste layer 200 is smaller than the thickness of the light emitting devices 310 , 320 , 330 is beneficial to the installation of the light emitting devices 310 , 320 , 330 .

[0129] Therefore, in an embodiment of the present invention, after applying the first slurry layer 200 for electrical connection, a second slurry layer 210 that can cover all steps between the light-emitting devices 310, 320, and 330 can be applied, thereby achieving stable electrical connection of the light-emitting devices 310, 320, and 330.

[0130] Figure 8FIG. 1 is a diagram showing an example of a light emitting device that can be applied to a display device using the light emitting device according to an embodiment of the present invention.

[0131] Figure 8 (A) shows a first surface of the light emitting device 310, Figure 8 (B) shows the second surface of the light emitting device 310 where the first-type electrode 312 and the second-type electrode 313 are located.

[0132] Such first-type electrode 312 and second-type electrode 313 may be electrically connected to semiconductor layer 311 of light emitting device 310. Although not shown separately, first-type electrode 312 may be connected to a first-type semiconductor (e.g., a p-type semiconductor), and second-type electrode 313 may be connected to a second-type semiconductor (e.g., an n-type semiconductor).

[0133] Reference Figure 8 (C), the red light emitting device 310 may have a first height h1. A growth substrate 314 may be disposed on the first surface of the light emitting device 310. Alternatively, a structure for light extraction may also be disposed on the first surface.

[0134] Fig. 9 : is a photograph showing a cross section of a display device manufactured by a common manufacturing process as a comparative example. Fig.10 This is a photograph showing a cross section of a display device manufactured according to one embodiment of the present invention.

[0135] As an example, Fig. 9 A cross section of a display device including a single paste layer is shown.

[0136] Reference Fig. 9 , there is a height deviation between the light emitting devices 31, 32, and 33. At this time, it can be seen that during the bonding process of the light emitting devices 31, 32, and 33, in the case of the light emitting device 32 located in the center, the electrode surface on the lower side of the light emitting device 32 and the electrode pad are not electrically connected and a gap A is generated.

[0137] This light emitting device 32 is not fixed on the electrode pad due to height deviation during the pressing process, resulting in a phenomenon in which the gap between the light emitting device 32 and the electrode pad becomes wider.

[0138] In other words, it can be seen that when bonding, the local part where weak bonding pressure is applied will rebound (spring back) to the original position at the moment the pressure is removed after bonding, resulting in separation through the contact of the conductive ball.

[0139] On the contrary, refer to Fig.10It can be seen that the light emitting devices 310, 320, 330 with thickness deviation are stably bonded on the electrode pad through the structure and manufacturing process as described above.

[0140] Reference Fig.10 , a first paste layer 200 including conductive particles and a second paste layer 210 for fixing the light emitting devices 310 , 320 , 330 can be confirmed in the cross section.

[0141] At this time, a hanging phenomenon in which the hanging structures 201 and 202 are respectively formed between the first light emitting device 310 and the second light emitting device 320 and between the second light emitting device 320 and the third light emitting device can be confirmed.

[0142] The narrower the interval between the light emitting devices 310, 320, and 330, the more difficult the bonding is, and an appropriate interval may be determined according to the visibility of the display module.

[0143] In the structure of the display device of the embodiment of the present invention, the height of the light emitting devices 310, 320, 330 is about 1.2 times the spacing between the light emitting devices 310, 320, 330. Considering that the mounting accuracy (in the Pick and Place method) is ±15 μm, it can be seen that stable bonding can be formed when the height of the light emitting devices 310, 320, 330 is 1 times the spacing.

[0144] Fig.11 is a photograph showing the screen state of a display device of a comparative example. Fig.12 1 is a photograph showing the screen state of a display device according to an embodiment of the present invention.

[0145] Fig.11 (A) and Fig.12 (A) shows a state where the green light emitting device 320 is lit, Fig.11 (B) and Fig.12 (B) shows a state where the red light emitting device 310 is lit.

[0146] Compare Fig.11 and Fig.12 It can be seen that when the display is emitting light, the proportion of defective pixels in the display device of one embodiment of the present invention is greatly reduced.

[0147] The above description is only an exemplary description of the technical concept of the present invention. Ordinary technicians in the technical field of the present invention can make various modifications and variations without departing from the essential features of the present invention.

[0148] Therefore, the embodiments disclosed in the present invention are not intended to limit the technical concept of the present invention but to explain it, and the scope of the technical concept of the present invention is not limited by such embodiments.

[0149] The protection scope of the present invention should be interpreted by the claims, and should be interpreted that all technical ideas within the scope equivalent to the claims belong to the scope of the present invention.

[0150] Industrial Applicability

[0151] According to the present invention, it is possible to provide a display device using a semiconductor light emitting device such as a micro LED.

Claims

1. A display device using a light-emitting device, characterized in that: The display device comprises: Wiring substrate; An electrode pad, defining a unit sub-pixel region and arranged on the wiring substrate; A light emitting device, wherein a first type electrode is arranged on the electrode pad; A connecting portion, comprising a plurality of conductive particles for electrically connecting the first type electrode of the light emitting device and the electrode pad; A first slurry layer, located on the light emitting device and the connecting portion; and The second slurry layer is located on the first slurry layer.

2. The display device using the light emitting device according to claim 1, characterized in that: At least one of the first slurry layer and the second slurry layer is provided in units of one pixel region.

3. The display device using the light emitting device according to claim 1, characterized in that: The height of the first paste layer is the same as the top surface of the light emitting device.

4. The display device using the light emitting device according to claim 1, characterized in that: The maximum height of the first paste layer corresponds to the highest height in the light emitting device.

5. The display device using the light emitting device according to claim 1, characterized in that: The display device further includes a covering layer located on the second paste layer.

6. The display device using the light emitting device according to claim 1, characterized in that: The interface between the first slurry layer and the second slurry layer connects the adjacent light emitting devices.

7. The display device using the light emitting device according to claim 6, characterized in that: An interface between the first paste layer and the second paste layer has an overhang structure between adjacent light emitting devices.

8. The display device using the light emitting device according to claim 6, characterized in that: The height of the overhanging structure is greater than the height deviation of the adjacent light emitting devices.

9. The display device using the light emitting device according to claim 6, characterized in that: The height of the overhanging structure is more than half of the height of the light emitting device.

10. The display device using the light emitting device according to claim 1, characterized in that: The second slurry layer includes at least one of reflective particles and black particles.

11. The display device using the light emitting device according to claim 1, characterized in that: The second paste layer is used to prevent the light emitting device from being separated from the electrode pad.

12. A method for manufacturing a display device using a light-emitting device, characterized in that: include: The step of applying a first slurry layer containing conductive particles on a wiring substrate having electrode pads arranged thereon; A step of configuring a light emitting device on the electrode pad; The step of coating a second slurry layer on the first slurry layer; as well as A step of pressing to electrically connect the light emitting device to the electrode pad.

13. The method for manufacturing a display device using a light emitting device according to claim 12, characterized in that: The step of applying a first slurry layer containing the conductive particles comprises: a step of transferring the conductive particles to the electrode pad; and The step of coating the first slurry layer on the electrode pad to which the conductive particles are transferred.

14. The method for manufacturing a display device using a light emitting device according to claim 12, characterized in that: The first slurry layer and the second slurry layer have different curing speeds from each other.

15. The method for manufacturing a display device using a light emitting device according to claim 12, characterized in that: In the pressing step, the first bonding head is located on the second slurry layer and the second bonding head is located on the lower side of the power distribution substrate, and the first bonding head and the second bonding head are pressed in a direction approaching each other.

16. The method for manufacturing a display device using a light emitting device according to claim 12, characterized in that: The pressing step is performed while heating.

17. The method for manufacturing a display device using a light-emitting device according to claim 12, characterized in that: At least one of the first slurry layer and the second slurry layer is applied in units of one pixel region.

18. The method for manufacturing a display device using a light emitting device according to claim 12, characterized in that: The height of the light emitting device has a deviation of 10 to 20 μm.

19. The method for manufacturing a display device using a light emitting device according to claim 12, characterized in that: The distance between adjacent electrode pads is 35 μm or less.

20. The method for manufacturing a display device using a light emitting device according to claim 12, characterized in that: The second paste layer is used to prevent the light emitting device from being separated from the electrode pad due to the elasticity of the conductive particles after the pressing step.

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