Light-emitting device

Abstract

A light-emitting device includes a circuit substrate, a light-emitting element, a scattering layer and a micro-bump. The light-emitting element is disposed on the circuit substrate and electrically connected to the circuit substrate. The scattering layer is disposed on the circuit substrate and surrounds the light-emitting element. The micro-bump is disposed over and overlapped with the light-emitting element. The micro-bump has a bottom surface and a inclined surface at its side, and an angle θ is included between the bottom surface and the inclined surface. The micro-bump has a total reflection angle θc, and θ ranges from θc to (θc

Description

[Technical Field]

[0001] The present invention relates to an optoelectronic device, and more particularly to a light-emitting device. [Previous Technology]

[0002] Micro LED light-emitting devices directly use micro LED chips as light-emitting units, and achieve the effect of full-surface display by encapsulating the light-emitting units on a circuit board. However, the operating current of current micro LED chips is very large, and their external quantum efficiency (EQE) will decrease as the operating current increases. [Summary of the Invention]

[0003] The present invention provides a light-emitting device with improved optical efficiency and reduced power consumption.

[0004] One embodiment of the present invention provides a light-emitting device, including a circuit board, a light-emitting element, a scattering layer, and microbumps. The light-emitting element is located on the circuit board and is electrically connected to the circuit board. The scattering layer is located on the circuit board and surrounds the light-emitting element. The microbumps are located on top of the light-emitting element and overlap the light-emitting element, wherein the microbumps have a bottom surface and an inclined surface located on its side, with an included angle θ between the bottom surface and the inclined surface, and the total internal reflection angle of the microbumps is θc, and θc ≤ θ ≤ (θc + 10°).

[0005] In one embodiment of the present invention, the cross-section of the microbump is trapezoidal.

[0006] In one embodiment of the present invention, the microbump has a flat top surface.

[0007] In one embodiment of the present invention, the width of the short side of the top surface of the microbump is 40% to 60% of the width of the short side of the light-emitting element.

[0008] In one embodiment of the present invention, the height of the microbump is 25% to 50% of the width of the short side of the light-emitting element.

[0009] In one embodiment of the present invention, the length of the long side of the top surface of the microbump is 40% to 60% of the length of the long side of the light-emitting element.

[0010] In one embodiment of the present invention, the refractive index of the microbumps is 1.6 to 1.8.

[0011] In one embodiment of the present invention, the top surface of the microbump has multiple recesses extending along the long side of the light-emitting element, and the multiple recesses are arranged along the short side of the light-emitting element.

[0012] In one embodiment of the present invention, the light-emitting element is located in the transposed area or repair area of ​​the sub-pixel of the light-emitting device, and the transposed area and repair area of ​​the sub-pixel are completely overlapped by the orthogonal projection of the microbump on the circuit board.

[0013] In one embodiment of the present invention, the light-emitting device further includes a light-shielding layer located on the scattering layer and not overlapping the light-emitting element.

[0014] In one embodiment of the present invention, the microbump further includes an extension layer located on the side of the microbump closer to the light-emitting element, and a light-shielding layer located between the extension layer and the scattering layer of the microbump.

[0015] In one embodiment of the present invention, the light-emitting device further includes a planar layer located between the microbumps and the light-emitting element.

[0016] In one embodiment of the present invention, the light-shielding layer is located between the planarization layer and the scattering layer.

[0017] In order to make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below, and detailed descriptions are given in conjunction with the accompanying drawings.

Implementation Method

[0018] In the accompanying drawings, the thicknesses of layers, films, panels, regions, etc., are enlarged for clarity. Throughout the specification, the same reference numerals denote the same elements. It should be understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "connected" to another element, it may be directly on or connected to the other element, or intermediate elements may also be present. Conversely, when an element is referred to as being "directly on" or "directly connected" to another element, no intermediate elements are present. As used herein, "connection" may refer to a physical and / or electrical connection. Furthermore, "electrical connection" or "coupling" may mean that other elements exist between the two elements.

[0019] It should be understood that although the terms "first," "second," "third," etc., may be used herein to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Therefore, the first "element," "component," "region," "layer," or "part" discussed below may be referred to as a second element, component, region, layer, or part without departing from the teachings of this document.

[0020] The terminology used herein is for the purpose of describing particular embodiments only and is not restrictive. As used herein, unless the content clearly indicates otherwise, the singular forms "a," "an," and "the" are intended to include the plural forms, including "at least one" or indicating "and / or." As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. It should also be understood that, when used in this specification, the terms "comprising" and / or "including" specify the presence of the stated features, areas, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, areas, integrals, steps, operations, elements, components, and / or combinations thereof.

[0021] Furthermore, relative terms such as “down” or “bottom” and “up” or “top” may be used herein to describe the relationship between one element and another element, as shown in the figures. It should be understood that relative terms are intended to include different orientations of the device other than those shown in the figures. For example, if a device in one figure is flipped, an element described as being “down” to another element will be oriented “up” to the other element. Thus, the exemplary term “down” can include both “down” and “up” orientations, depending on the specific orientation of the figure. Similarly, if a device in one figure is flipped, an element described as being “down” or “below” to another element will be oriented “above” the other element. Thus, the exemplary term “down” or “below” can include both “up” and “down” orientations.

[0022] Given the specific number of measurements discussed and the associated errors (i.e., limitations of the measurement system), the terms "about," "approximately," or "substantially" as used herein include the value and the average value within an acceptable range of deviations of the specific value as determined by one of ordinary skill in the art. For example, "about" may mean within one or more standard deviations of the value, or within ±30%, ±20%, ±10%, ±5%. Furthermore, the terms "about," "approximately," or "substantially" as used herein may be chosen based on optical, etched, or other properties to select a more acceptable range of deviations or standard deviations, rather than applying a single standard deviation to all properties.

[0023] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having the same meaning as they have in the context of the relevant technology and the invention, and will not be interpreted as having an idealized or overly formal meaning unless expressly defined herein.

[0024] Exemplary embodiments are described herein with reference to cross-sectional views as schematic representations of idealized embodiments. Therefore, variations in shape as a result of, for example, manufacturing techniques and / or tolerances can be expected. Consequently, the embodiments described herein should not be construed as limited to the specific shapes of the regions shown herein, but rather include, for example, shape deviations caused by manufacturing processes. For example, regions shown or described as flat may generally have rough and / or non-linear characteristics. Furthermore, acute angles shown may be rounded. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to show the precise shapes of the regions, nor are they intended to limit the scope of the claims.

[0025] FIG1A is a top view schematic diagram of a light-emitting device 10 according to an embodiment of the present invention. FIG1B is a cross-sectional schematic diagram taken along section line A-A' of FIG1A. FIG1C is an enlarged view of region I of FIG1B. FIG1D is a top view schematic diagram of the light-emitting element 120, planarization layer 140, microbump 150 and light-shielding layer 160 of the light-emitting device 10 of FIG1A. In order to simplify the illustration, FIG1A schematically shows the circuit board 110, the light-emitting element 120 and the driving element DC, and other components are omitted. The embodiments of the various elements of the light-emitting device 10 are further described below, but are not limited thereto.

[0026] First, referring to Figures 1A and 1B, the circuit board 110 of the light-emitting device 10 may include a base plate 112 and a circuit layer 114 located on the base plate 112. The base plate 112 may be a transparent base plate or a non-transparent base plate, and its material may be quartz, glass, polymer or other suitable materials, but is not limited thereto. The circuit layer 114 may include a plurality of pads PA and PB, which may be disposed, for example, inside the circuit layer 114 or on the upper surface of the circuit layer 114. In addition, the circuit layer 114 may selectively include lines or components required by the light-emitting device 10, such as power lines, drive signal lines, timing signal lines, detection signal lines, current compensation lines, drive elements, switching elements, storage capacitors, etc., and the above-mentioned lines or components may be electrically connected to lines or components outside the circuit board 110 through the pads PA and PB.

[0027] The light-emitting device 10 may include, for example, a plurality of light-emitting elements 120 arranged in an array to provide a uniform surface light source. In some embodiments, the light-emitting device 10 may serve as a display device. For example, the light-emitting device 10 includes a plurality of sub-pixels PXs arranged in an array, and each sub-pixel PXs may include a light-emitting element 120 and associated driving circuitry. In some embodiments, the plurality of light-emitting elements 120 are all blue light-emitting diodes, and the light-emitting device 10 may further include a color conversion layer (not shown) disposed on the plurality of light-emitting elements 120, wherein the color conversion layer may include phosphors or similar wavelength conversion materials to convert the blue light emitted by the blue light-emitting diodes into light of different colors to achieve a full-color display effect. In other embodiments, the plurality of light-emitting elements 120 may include a plurality of red light-emitting diodes, a plurality of green light-emitting diodes, and a plurality of blue light-emitting diodes to achieve a full-color display effect. When the light-emitting colors of the plurality of light-emitting elements 120 are different from each other and can be mixed to produce various desired light colors, a color conversion layer may not be required. In other embodiments, the plurality of light-emitting elements 120 may all be white light-emitting diodes, and the accompanying color conversion layer may be a color filter layer, thus achieving a full-color display effect.

[0028] In some embodiments, the light-emitting device 10 may further include a driving element DC, which may be electrically connected to sub-pixels PXs to transmit signals to the light-emitting element 120 and associated driving lines. For example, in the sub-pixels PXs, the light-emitting element 120 is electrically connected to pads PA and PB, and the driving element DC may be electrically connected to pads PA and PB in each sub-pixel PXs, respectively. In some embodiments, the pads PA in the plurality of sub-pixels PXs are separate from each other and independently receive signals provided by the driving element DC. In some embodiments, the pads PB in the plurality of sub-pixels PXs may be electrically connected to each other and / or the pads PB are subjected to the same common voltage during operation. In some embodiments, the driving element DC may be a wafer bonded to the circuit board 110 or a circuit element (including active elements, passive elements, or combinations thereof) formed directly in the circuit board 110.

[0029] In some embodiments, the light-emitting element 120 may be fabricated on a growth substrate (e.g., a sapphire substrate) and then transferred onto a circuit board 110 via a mass transfer process, and electrically connected to pads PA and PB. Therefore, the light-emitting device 10 has, for example, a chip-on-board (COB) package. The light-emitting element 120 may be a flip-chip light-emitting diode, and the light-emitting element 120 may be electrically connected to corresponding pads PA and PB on the circuit board 110 via two electrodes located on the same side of the epitaxial structure. In some embodiments, the light-emitting element 120 may also be a vertical light-emitting diode, and the electrode on the side of the light-emitting element 120 facing away from the circuit board 110 may be electrically connected to corresponding pads PA or PB on the circuit board 110 via connecting wires. In some embodiments, other conductive materials or conductive adhesives, such as solder or anisotropic conductive adhesive (ACF), may also be included between the light-emitting element 120 and the pads PA and PB.

[0030] The scattering layer 130 is located on the circuit board 110, and the scattering layer 130 can surround the light-emitting element 120. Since the light-emitting element 120 may be misaligned when it is transferred onto the circuit board 110 through the mass transfer process, resulting in asymmetry of the viewing angle and color shift of the light-emitting device 10, the scattering layer 130 can expand the light-emitting area to the periphery of the light-emitting element 120, thereby reducing the degree of asymmetry of the viewing angle and color shift caused by the misalignment of the light-emitting element 120.

[0031] The scattering layer 130 may include a substrate and scattering particles dispersed within the substrate. For example, the substrate material may include resins such as silicone resin, epoxy resin, acrylic, polycarbonate (PC), etc., but is not limited thereto. In some embodiments, the substrate material is poly(methyl methacrylate), PMMA. The scattering particles may include organic polymer light-transmitting materials or inorganic light-transmitting materials, such as polyvinyl chloride (PVC), polycarbonate (PC), polyethylene (PE), silicon oxide (SiO2), or titanium dioxide (TiO2), etc., but is not limited thereto.

[0032] For example, after the light-emitting element 120 is provided, a liquid resin containing scattering particles can be applied to the circuit board 110, and the liquid resin can be allowed to flow and spread throughout the entire circuit board 110, and flow between the light-emitting element 120 and the circuit board 110. Subsequently, the liquid resin can be further cured to form a scattering layer 130.

[0033] In some embodiments, the light-emitting device 10 may further include a planarization layer 140, which is disposed on the side of the light-emitting element 120 and the scattering layer 130 facing away from the circuit substrate 110. In other words, the light-emitting element 120 and the scattering layer 130 may be located between the planarization layer 140 and the circuit substrate 110. The material of the planarization layer 140 may include optically clear adhesive (OCA), pressure-sensitive adhesive (PSA), silicone adhesive, polyurethane reactive (PUR) adhesive, polyurethane (PU) adhesive, or other suitable optical-grade adhesives. In some embodiments, the planarization layer 140 is selected from optically clear adhesives with high transmittance, and the transmittance of the planarization layer 140 may be greater than 90%, but is not limited thereto. In some embodiments, the refractive index of the planarization layer 140 is about 1.4 to 1.6, for example about 1.5, but is not limited thereto.

[0034] Microbumps 150 may be disposed above the light-emitting element 120, and the microbumps 150 may overlap the light-emitting element 120. For example, the microbumps 150 are disposed on the upper surface of the planarization layer 140, and the planarization layer 140 is sandwiched between the microbumps 150 and the light-emitting element 120. In some embodiments, a plurality of microbumps 150 separated from each other may each correspond to a plurality of light-emitting elements 120 arranged in an array. In some embodiments, a plurality of microbumps 150 separated from each other may be arranged in an array, and each microbump 150 corresponds to a corresponding light-emitting element 120. The microbumps 150 may include a high refractive index material. In some embodiments, the refractive index of the microbumps 150 is about 1.6 to 1.8, for example, about 1.75, but is not limited thereto. For example, the microbumps 150 include a photoresist substrate and filler particles, and the filler particles are dispersed in the photoresist substrate. In some embodiments, the photoresist substrate is made of at least one or a combination of acrylic resin, epoxy resin, and organosiloxane resin, but is not limited thereto. In some embodiments, the filler particles are made of at least one or a combination of titanium dioxide (TiO2), titanium nitride (TiNx), and silicon nitride (SiNx), but are not limited thereto. By providing microbumps 150 to focus the light emitted by the light-emitting element 120 to the positive viewing angle, the secondary optical efficiency of the light-emitting element 120 can be improved, thereby increasing the positive viewing angle luminance of the light-emitting device 10. In this way, the same positive viewing angle luminance can be obtained with a reduced operating current, thus reducing the power consumption of the light-emitting device 10 while having a higher EQE.

[0035] Referring to Figure 1C, the microbump 150 may have a trapezoidal structure, and the cross-section of the microbump 150 may be trapezoidal. For example, the microbump 150 has a top surface 152, a bottom surface 154, and an inclined surface 156, and the area of ​​the top surface 152 may be smaller than the area of ​​the bottom surface 154. In some embodiments, the geometric center of the top surface 152 overlaps with the geometric center of the bottom surface 154. The inclined surface 156 may connect the top surface 152 and the bottom surface 154, and an angle θ may be between the inclined surface 156 and the bottom surface 154. By making the angle θ greater than or equal to the total internal reflection angle θc of the microbump 150 and less than or equal to the total internal reflection angle θc plus 10°, i.e., θc ≤ θ ≤ (θc+10°), the secondary optical efficiency of the light-emitting element 120 can be improved.

[0036] The top surface 152 of the microbump 150 may be a generally flat surface. In some embodiments, the top surface 152, bottom surface 154, and inclined surface 156 are all generally flat surfaces. In some embodiments, the microbump 150 is arranged based on an alignment pattern on the circuit board 110. In some embodiments, the geometric center of the microbump 150 may overlap with the geometric center of the light-emitting element 120. In some embodiments, during the process of transferring the light-emitting element 120 to a predetermined position on the circuit board 110 through a mass transfer process, the actual placement position may deviate from the predetermined position, causing the geometric center of the microbump 150 to not overlap with the geometric center of the light-emitting element 120. By making the top surface 152 of the microbump 150 a generally flat surface, the impact of the actual placement position of the light-emitting element 120 deviating from the predetermined position on the uniformity of the emitted light brightness of the light-emitting device 10 can be reduced, thereby helping to mitigate color shift.

[0037] In some embodiments, the scattering layer 130 rises along the sidewall 120S of the light-emitting element 120, such that an angle φ facing the sidewall 120S is formed between the extension line of the inclined upper surface 130T1 of the scattering layer 130 adjacent to the light-emitting element 120 and the horizontal upper surface 130T2 of the scattering layer 130. In some embodiments, the angle φ is about 20° to 40°, for example 30°, but is not limited thereto.

[0038] Referring to Figures 1A, 1B, and 1D, the light-emitting device 10 may further include a light-shielding layer 160, which may be located above the scattering layer 130 and not overlap with the light-emitting elements 120. The orthographic projection of the light-shielding layer 160 onto the circuit board 110 may be located between the orthographic projections of the plurality of light-emitting elements 120 onto the circuit board 110, that is, the light-shielding layer 160 can shield the surface of the circuit board 110 between the light-emitting elements 120. In some embodiments, the light-shielding layer 160 has a plurality of openings OP, and the plurality of openings OP respectively overlap the light-emitting elements 120 of a plurality of sub-pixels PXs arranged in an array, thereby controlling the light emission range of each sub-pixel. In some embodiments, the light-shielding layer 160 is located on the upper surface of the planarization layer 140, that is, the bottom surface of the light-shielding layer 160 and the bottom surface 154 of the microbump 150 are located on the same horizontal plane, and the light-shielding layer 160 may surround the microbump 150. In some embodiments, the thickness of the light-shielding layer 160 is from about 0.5 μm to 1.5 μm, for example, about 1 μm, but is not limited thereto. In some embodiments, the material of the light-shielding layer 160 is ink or other suitable material.

[0039] Referring to FIG. 1B, the light-emitting device 10 may further include an encapsulation layer 170. The encapsulation layer 170 may cover the light-emitting element 120, the microbumps 150, the planarization layer 140, and the light-shielding layer 160. The encapsulation layer 170 may, for example, prevent moisture from entering to maintain the performance and lifespan of the light-emitting element 120. The encapsulation layer 170 may have high transmittance; for example, the transmittance of the encapsulation layer 170 may be greater than 95%, but is not limited thereto. The material of the encapsulation layer 170 may include transparent adhesives, such as PUR adhesive, epoxy resin, silicone, or other suitable adhesives, but is not limited thereto. In some embodiments, the material of the encapsulation layer 170 is the same as the material of the planarization layer 140. In some embodiments, the refractive index of the encapsulation layer 170 is about 1.45 to 1.65, for example, about 1.6, but is not limited thereto.

[0040] The light-emitting device 10 may further include a cover plate 180, which may be located on the encapsulation layer 170 as a protective cover for the light-emitting device 10. The cover plate 180 may include a transparent sheet material, such as glass, a polymer (e.g., polyimide), or other suitable materials. In some embodiments, the cover plate 180 may also include an anti-reflective and anti-glare film to adjust the overall reflectivity, anti-glare performance, and surface flatness of the light-emitting device 10 under ambient light illumination.

[0041] Referring to Figure 1C, when the angle θ1 between the light ray R1 emitted from the light-emitting element 120 and the normal N perpendicular to the upper surface of the light-emitting element 120 (i.e., the positive viewing direction) is less than the angle θ of the micro-bump 150, the inclined surface 156 of the micro-bump 150 will cause the light ray R1 to become a light ray R1' that converges towards the positive viewing direction. When the angle θ2 between the light ray R2 emitted from the light-emitting element 120 and the normal N is greater than the angle θ, the inclined surface 156 will cause the light ray R2 to become a light ray R2' that diverges in a direction away from the positive viewing direction. When the angle θ of the micro-bump 150 is greater than the total internal reflection angle θc of the micro-bump 150, the inclined surface 156 will cause the light rays that can leave the micro-bump 150 to converge towards the positive viewing direction, and the light rays with a greater than the total internal reflection angle will not affect the light output efficiency even if they diverge more. Therefore, the angle θ of the micro-bump 150 can be greater than or equal to the total internal reflection angle θc of the micro-bump 150, that is, θc ≤ θ. Furthermore, Table 1 below shows the percentage of the light intensity at the frontal viewing angle of the light-emitting device 10 when only the angle θ of the microbump 150 is changed under the same conditions. The refractive index of the microbump 150 is 1.77, and the total internal reflection angle θc is approximately 34.4°. The percentage of light intensity is based on the frontal viewing angle light intensity when the scattering layer 130, planarization layer 140, microbump 150, light-shielding layer 160, and cover plate 180 are absent from the light-emitting device 10. In other words, the percentage of light intensity is based on the frontal viewing angle light intensity when the light-emitting element 120 is disposed on the circuit board 110 and the encapsulation layer 170 covers the light-emitting element 120. As can be seen from Table 1, the focusing effect at angles θ of 35°, 40°, and 45° is significantly better than the focusing effect at an angle θ of 30°. Therefore, a better light-gathering effect is achieved when the angle θ of the microbump 150 is greater than or equal to the total internal reflection angle θc of the microbump 150 and less than or equal to the total internal reflection angle θc plus 10°, that is, θc ≤ θ ≤ (θc+10°). In Table 1, the X direction is the extension direction of the long side of the light-emitting element 120, and the Y direction is the extension direction of the short side of the light-emitting element 120. [Table 1] X-direction angle θ (The Y-direction is fixed at 45°) Positive viewing angle light intensity % Y-direction angle θ (X direction fixed at 40°) Positive viewing angle light intensity % 45° 149.7% 45° 150.2% 40° 150.2% 40° 149.1% 35° 150% 35° 145.8% 30° 147.1% 30° 140.3%

[0042] To maximize the luminance at the frontal viewing angle, the short side width W1 of the top surface 152 of the microstructure 150 can be designed to be 50% ± 10% of the short side width W of the light-emitting element 120, to achieve a relatively better light-gathering effect. Referring to Figure 1D, a series of tests were conducted on the influence of the short side width W1 and long side length L1 of the top surface 152 of the microbump 150 on the luminous intensity % at the frontal viewing angle of the light-emitting device 10, and the test results are listed in Table 2 below. The angle θ of the microbump 150 is 45°. Where L is the long side length of the light-emitting element 120, and W is the short side width of the light-emitting element 120. [Table 2] W1*L1 Positive viewing angle light intensity % 20%W*35%L 137.2% 20%W*60%L 138.8% 40%W*45%L 145.8% 40%W*70%L 148.6% 60%W*55%L 144.3% 60%W*80%L 149.7% 80%W*65%L 143.7% 80%W*90%L 145.5%

[0043] As can be seen from Table 2, the influence of the short side width W1 of the top surface 152 on the light-gathering effect is significantly greater than the influence of the long side length L1 of the top surface 152 on the light-gathering effect. When the short side width W1 of the top surface 152 is about 40% to 60% of the short side width W of the light-emitting element 120, a relatively better light-gathering effect can indeed be obtained.

[0044] In addition, to avoid excessive color shift, the height H of the microstructure 150 can be designed to be approximately 25% to 50% of the short side width W of the light-emitting element 120. Referring to Figures 1C and 1D, a series of tests were conducted on the influence of the height H of the microbump 150 and the long side length L1 of the top surface 152 of the microbump 150 on the positive viewing angle light intensity % and color shift of the light-emitting device 10, and the test results are listed in Tables 3 and 4 below. [Table 3] H W1*L1 Positive viewing angle light intensity % (ΔLx+ΔLy) / 2 30%W 60%W*55%L 139.6% 12% 50%W 60%W*55%L 152.8% 15% 70%W 60%W*55%L 166.3% 17% [Table 4] H W1*L1 Positive viewing angle light intensity % (ΔLx+ΔLy) / 2 50%W 60%W*30%L 151.4% 17% 50%W 60%W*55%L 152.8% 15% 50%W 60%W*80%L 158.6% 17%

[0045] In Tables 3 and 4, ΔLx represents the percentage of the maximum brightness difference between the three measured brightness values ​​when the light-emitting element 120 is viewed at the same angle (e.g., the angle with the most severe color shift), under three conditions: the central axis of the light-emitting element 120 does not deviate from (i.e., overlaps with) the central axis of the micro-bump 150, and the central axis of the light-emitting element 120 deviates from the central axis of the micro-bump 150 in the x direction by +20%W and -20%W, i.e., color shift in the x direction; ΔLy represents the percentage of the maximum brightness difference between the three measured brightness values ​​when the light-emitting element 120 is viewed at the same angle, under three conditions: the central axis of the light-emitting element 120 overlaps with the central axis of the micro-bump 150, and the central axis of the light-emitting element 120 deviates from the central axis of the micro-bump 150 in the y direction by +20%W and -20%W, i.e., color shift in the y direction.

[0046] As can be seen from Table 3, under the same short side width W1 and long side length L1, the positive viewing angle light intensity % generally increases as the height H of the micro-bump 150 increases from 30%W to 70%W. However, the average values ​​of ΔLx and ΔLy also increase slightly, indicating a slight increase in color shift. When the height H is 30%W and 50%W, relatively small average values ​​of ΔLx and ΔLy (below 15%) and acceptable positive viewing angle light intensity % can be obtained.

[0047] As can be seen from Table 4, under the same height H and the same short side width W1 of the top surface 152, when the long side length L1 of the top surface 152 is about 40% to 60% of the long side length L of the light-emitting element 120, a relatively small average value of ΔLx and ΔLy can be obtained.

[0048] FIG1E is a scanning electron microscope (SEM) image of the microbump 150 of the light-emitting device 10 according to an embodiment of the present invention. As can be seen from FIG1E, the microbump 150 has an angle θ of about 42.8° and a height H of about 5.56 μm.

[0049] FIG2 is a cross-sectional schematic diagram of a light-emitting device 20 according to an embodiment of the present invention. The light-emitting device 20 includes a circuit board 110, a light-emitting element 120, a scattering layer 130, a planarization layer 140, microbumps 150, a light-shielding layer 160, an encapsulation layer 170, and a cover plate 180. Compared with the light-emitting device 10 shown in FIG1, the main difference of the light-emitting device 20 shown in FIG2 is that the microbumps 150 of the light-emitting device 20 further include an extension layer 158. The extension layer 158 is located on the side of the microbumps 150 closer to the light-emitting element 120. During the formation of the microbumps 150 having an angle θ, the extension layer 158 can help control the angle θ and prevent the angle θ from becoming an obtuse angle due to, for example, etching undercut. Therefore, the extension layer 158 helps to form the angle θ as an acute angle.

[0050] In some embodiments, the extension layer 158 is located between the microbump 150 and the light-emitting element 120. In some embodiments, the extension layer 158 is sandwiched between the microbump 150 and the planarization layer 140. In some embodiments, the light-shielding layer 160 is sandwiched between the extension layer 158 of the microbump 150 and the planarization layer 140.

[0051] FIG3 is a cross-sectional schematic diagram of a light-emitting device 30 according to an embodiment of the present invention. The light-emitting device 30 includes a circuit board 110, a light-emitting element 120, a scattering layer 130, a planarization layer 140, microbumps 150, a light-shielding layer 160, an encapsulation layer 170, and a cover plate 180. Compared with the light-emitting device 10 shown in FIG1, the main difference of the light-emitting device 30 shown in FIG3 is that the light-shielding layer 160 of the light-emitting device 30 can be located between the scattering layer 130 and the planarization layer 140. In some embodiments, the light-shielding layer 160 covers the upper surface of the scattering layer 130 between the light-emitting elements 120 and extends to the sidewall 120S of the light-emitting element 120, so as to more comprehensively absorb the reflected light of the incident light incident on the circuit board 110, thereby avoiding interference of these reflected lights with the light emitted by the light-emitting element 120.

[0052] FIG4 is a cross-sectional schematic diagram of a light-emitting device 40 according to an embodiment of the present invention. The light-emitting device 40 includes a circuit board 110, a light-emitting element 120, a scattering layer 130, a planarization layer 140, a microbump 150, a light-shielding layer 160, an encapsulation layer 170, and a cover plate 180. Compared with the light-emitting device 30 shown in FIG3, the main difference of the light-emitting device 40 shown in FIG4 is that the microbump 150 of the light-emitting device 40 further includes an extension layer 158, which is located on the side of the microbump 150 closer to the light-emitting element 120, so as to help to form an acute angle θ.

[0053] FIG5A is a top view schematic diagram of a light-emitting device 50 according to an embodiment of the present invention. FIG5B is a cross-sectional schematic diagram taken along section line B-B' of FIG5A. Referring to FIG5A and FIG5B, the light-emitting device 50 includes a circuit board 110, a light-emitting element 120, a scattering layer 130, a planarization layer 140, microbumps 150, an extension layer 158, a light-shielding layer 160, an encapsulation layer 170, and a cover plate 180. Compared with the light-emitting device 20 shown in FIG2, the main difference of the light-emitting device 50 shown in FIG5A and FIG5B is that the top surface of the microbumps 150 of the light-emitting device 50 has multiple recesses 155 extending along the long side direction Dx of the light-emitting element 120, and the multiple recesses 155 can be arranged along the short side direction Dy of the light-emitting element, so that the upper surface of the microbumps 150 has a curtain-like undulation. In this way, the secondary optical efficiency of the light-emitting device 50 can be further improved and color shift can be reduced.

[0054] In some embodiments, each sub-pixel PXs of the light-emitting device 50 has a transpose region AM and a repair region AR. The transpose region AM can be the area where the light-emitting element 120 is transposed into the sub-pixel PXs through a mass transfer process, and the repair region AR can be the area where another light-emitting element 120 is set through a repair process when the light-emitting element 120 is not successfully transposed into the transpose region AM on the circuit board 110. For example, the light-emitting element 120R is successfully transposed into the transpose region AM in sub-pixel PX1 through a mass transfer process, so the repair region AR in sub-pixel PX1 does not need to undergo a repair process to set the light-emitting element. Conversely, because the light-emitting element is not successfully transposed into the transpose region AM in sub-pixel PX2, a repair process is needed to set the light-emitting element 120G into the repair region AR in sub-pixel PX2.

[0055] In some embodiments, the microbumps 150 of the light-emitting device 50 can cover the transposed region AM and the repair region AR of the sub-pixels PXs. In some embodiments, the orthographic projections of the transposed region AM and the repair region AR onto the circuit board 110 completely overlap the orthographic projections of the microbumps 150 onto the circuit board 110. For example, the short side of the microbumps 150 can extend along the long side direction Dx of the light-emitting element 120, and the long side of the microbumps 150 can extend along the short side direction Dy of the light-emitting element 120 into the transposed region AM and the repair region AR. That is, the microbumps 150 can span and cover the transposed region AM and the repair region AR within each sub-pixel PXs. In this way, regardless of whether the light-emitting element within the sub-pixel PXs is transposed through a mass transfer process or set through a repair process, the light-emitting device 50 can achieve improved secondary optical efficiency and reduced color shift through the microbumps 150.

[0056] In summary, the light-emitting device of the present invention improves the secondary optical efficiency of the light-emitting element by setting microbumps to focus light at a positive viewing angle, thereby increasing the luminance of the light-emitting device at a positive viewing angle. Furthermore, it can further reduce the current required by the light-emitting device, thereby reducing the power consumption of the light-emitting device. In addition, by making the microbumps have a flat upper surface and further forming multiple recesses on the flat upper surface, the light-emitting device can further improve the uniformity of light output brightness, thereby helping to reduce color shift.

[0057] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims. [Simplified Explanation of the Diagram]

[0058] FIG1A is a top view schematic diagram of a light-emitting device according to an embodiment of the present invention. FIG1B is a cross-sectional schematic diagram taken along section line A-A' of FIG1A. FIG1C is an enlarged view of region I of FIG1B. FIG1D is a top view schematic diagram of the light-emitting element, planarization layer, microbumps, and light-shielding layer of the light-emitting device of FIG1A. FIG1E is a scanning electron microscope (SEM) image of the microbumps of the light-emitting device according to an embodiment of the present invention. FIG2 is a cross-sectional schematic diagram of a light-emitting device according to an embodiment of the present invention. FIG3 is a cross-sectional schematic diagram of a light-emitting device according to an embodiment of the present invention. FIG4 is a cross-sectional schematic diagram of a light-emitting device according to an embodiment of the present invention. FIG5A is a top view schematic diagram of a light-emitting device according to an embodiment of the present invention. FIG5B is a cross-sectional schematic diagram taken along section line B-B' of FIG5A.

Claims

1. A light-emitting device, comprising: Circuit board; A light-emitting element is located on the circuit board and is electrically connected to the circuit board; A scattering layer is located on the circuit substrate and surrounds the light-emitting element; And a microbump, located on top of and overlapping the light-emitting element, wherein the microbump has a top surface, a bottom surface and an inclined surface located on its side, the area of ​​the top surface is smaller than the area of ​​the bottom surface, the bottom surface and the inclined surface are separated by an angle θ, and the total internal reflection angle of the light emitted from the microbump is θc, and θc ≤ θ ≤ (θc +10°).

2. The light-emitting device as claimed in claim 1, wherein the cross-section of the microbump is trapezoidal.

3. The light-emitting device as claimed in claim 1, wherein the microbump has a flat top surface.

4. The light-emitting device as claimed in claim 1, wherein the short side width of the top surface of the microbump is 40% to 60% of the short side width of the light-emitting element.

5. The light-emitting device as claimed in claim 1, wherein the height of the microbump is 25% to 50% of the width of the short side of the light-emitting element.

6. The light-emitting device as claimed in claim 1, wherein the length of the long side of the top surface of the microbump is 40% to 60% of the length of the long side of the light-emitting element.

7. The light-emitting device as claimed in claim 1, wherein the refractive index of the microbumps is 1.6 to 1.

8.

8. The light-emitting device as claimed in claim 1, wherein the top surface of the microbump has a plurality of recesses extending along the long side direction of the light-emitting element, and the plurality of recesses are arranged along the short side direction of the light-emitting element.

9. The light-emitting device as claimed in claim 8, wherein the light-emitting element is located in the transposed region or repair region of a sub-pixel of the light-emitting device, and the orthographic projection of the transposed region and the repair region of the sub-pixel onto the circuit board completely overlaps the orthographic projection of the microbump onto the circuit board.

10. The light-emitting device as claimed in claim 1 further includes a light-shielding layer located on the scattering layer and not overlapping the light-emitting element.

11. The light-emitting device of claim 10, wherein the microbump further comprises an extension layer located on the side of the microbump closer to the light-emitting element, and the light-shielding layer is located between the extension layer and the scattering layer of the microbump.

12. The light-emitting device as claimed in claim 10 further includes a planarization layer located between the microbumps and the light-emitting element.

13. The light-emitting device as claimed in claim 12, wherein the light-shielding layer is located between the planarization layer and the scattering layer.

14. The light-emitting device as claimed in claim 1, wherein the total internal reflection angle of the light emitted from the inclined surface of the microbump to the adjacent medium is θc.

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