LED light-emitting structure, preparation method and multi-layer stacked LED light-emitting structure

Abstract

The invention discloses an LED light-emitting structure, a preparation method and a multi-layer stacked LED light-emitting structure. The preparation method of the LED light-emitting structure comprises the following steps: providing a substrate; a plurality of LED chips are randomly distributed on at least the target area, after the plurality of LED chips are randomly distributed on at least the target area, LED chips with first electrodes in contact with the target area and LED chips with first electrodes not in contact with the target area are randomly formed, and the LED chips with the first electrodes in contact with the target area are called effective LED chips. The rest LED chips are called invalid LED chips; a packaging body wrapping all the LED chips is arranged at the outer part of the substrate; and preparing a second conductive layer above the packaging body, wherein the second conductive layer is electrically connected with the second electrode of the effective LED chip. And through a mode of randomly dispersing the LED chips, the production efficiency is improved, and the production cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of light-emitting device manufacturing technology, and in particular to an LED light-emitting structure, a preparation method, and a multi-layer stacked LED light-emitting structure. Background Technology

[0002] The manufacturing of display devices involves the transfer of a large number of LED chips. Depending on the resolution of the display screen, the number of LED chips to be transferred varies, typically involving hundreds of thousands or even tens of millions of LED chips. How to quickly and accurately transfer these tiny chips from the growth substrate to the target driving substrate, while ensuring the accuracy, efficiency, stability and yield of the transfer, has become the key to the large-scale commercial production of LEDs.

[0003] Currently, in order to achieve efficient transfer of LED chips, the industry has developed a variety of technologies for mass transfer of LED chips, among which the more common ones include electrostatic stamping, magnetic stamping, elastic stamping, laser-assisted transfer, and fluid self-assembly.

[0004] The transfer of existing LED chips usually requires placing each LED chip individually into the desired position, which involves a large number of chips, consumes a lot of time and resources, and usually requires high positional accuracy after the LED chips are assembled, resulting in high process requirements and high costs.

[0005] Therefore, it is necessary to improve the existing technology to overcome the aforementioned defects.

[0006] The above content is only used to help understand the technical solution of this application and does not constitute an admission that the above is prior art. Summary of the Invention

[0007] The purpose of this invention is to provide an LED light-emitting structure, a preparation method, and a multi-layer stacked LED light-emitting structure to reduce the difficulty of the process.

[0008] To achieve the above-mentioned objectives, in a first aspect, the present invention provides a method for fabricating an LED light-emitting structure, comprising the following steps:

[0009] S1. A substrate is provided, the surface of which is provided with a first conductive layer, the first conductive layer including a target area;

[0010] S2. Randomly distribute multiple LED chips on at least the target area. Each LED chip includes an electrode pair, which includes a first electrode and a second electrode located on opposite surfaces of the LED chip. After randomly distributing the multiple LED chips on at least the target area, LED chips with their first electrodes in contact with the target area and LED chips with their first electrodes not in contact with the target area are randomly formed. The LED chips with their first electrodes in contact with the target area are called effective LED chips, and the remaining LED chips are called ineffective LED chips.

[0011] S3. An encapsulation covering all the LED chips is provided on the outside of the substrate;

[0012] S4. A second conductive layer is prepared on top of the package, and the second conductive layer is electrically connected to the second electrode of the effective LED chip.

[0013] Furthermore, in step S2, each target area carries no fewer than 8 LED chips.

[0014] Furthermore, in step S2, randomly distributing the plurality of LED chips on at least the target area includes the following steps:

[0015] S21. Place multiple LED chips in a liquid to form an LED paste;

[0016] S22. Transfer the LED paste to at least the target area.

[0017] Furthermore, in step S22, the LED paste is transferred to the target area by screen printing, embossing, spraying, or printing.

[0018] Furthermore, in step S4, when the second conductive layer is formed above the package, an insulating layer is also formed to cover the second conductive layer, wherein the insulating layer and / or the substrate are made of a transparent material; or,

[0019] Step S3 further includes the following step: preparing a protective layer on the outside of the second conductive layer, wherein the protective layer and / or the substrate are made of a transparent material.

[0020] Furthermore, step S3 also includes the following step: thinning the upper surface of the package to expose the second electrode of the LED chip.

[0021] Furthermore, the first conductive layer includes multiple target regions, all of which are used to carry LED chips of the same emission color, or each target region is used to carry LED chips of two or three different emission colors.

[0022] Furthermore, in step S2, when the multiple LED chips are randomly distributed on at least the target area, the multiple LED chips are randomly distributed on the entire surface of the substrate, or the multiple LED chips are randomly distributed only within the range corresponding to the target area.

[0023] Furthermore, the first conductive layer includes two or three target regions, namely a first-color target region for carrying a first-color LED chip, a second-color target region for carrying a second-color LED chip, and a third-color target region for carrying a third-color LED chip. In step S2, when the LED chips are randomly scattered on at least the target regions, the LED chips of the corresponding light-emitting colors are randomly scattered in the target regions carrying LED chips of different light-emitting colors in several stages.

[0024] Furthermore, in step S2, when the LED chips are randomly distributed on at least the target area, two or three LED chips of different emitting colors are also randomly distributed on at least the target area.

[0025] Furthermore, the center of gravity of the LED chip is close to the first electrode.

[0026] Furthermore, the LED chip includes a metal mass block connected to its first electrode.

[0027] Furthermore, the cross-sectional area of ​​the end where the first electrode of the LED chip is located is larger than the cross-sectional area of ​​the end where the second electrode is located.

[0028] Furthermore, the LED chip is in the shape of a cuboid or a cube;

[0029] The LED chip includes two sets of electrode pairs, with the first electrodes of each set of electrode pairs located on two adjacent surfaces of the LED chip; or,

[0030] The LED chip includes three sets of electrode pairs, with the first electrode of each set of electrode pairs located on three adjacent surfaces of the LED chip.

[0031] Secondly, the present invention proposes an LED light-emitting structure, comprising:

[0032] A substrate, wherein a first conductive layer is provided on the surface of the substrate, and the first conductive layer includes a target area;

[0033] A plurality of LED chips are randomly distributed on at least the target area. Each LED chip includes an electrode pair, which includes a first electrode and a second electrode located on opposite surfaces of the LED chip. The position and orientation of the LED chips are random. One or more of the first electrodes of the LED chips are in contact with the target area. The LED chips whose first electrodes are in contact with the target area are called effective LED chips, and the remaining LED chips are called ineffective LED chips.

[0034] A package, covering the exterior of all the LED chips, with the second electrode of each LED chip exposed from the top surface of the package; and,

[0035] The second conductive layer is electrically connected to the second electrode of the effective LED chip.

[0036] Furthermore, the LED light-emitting structure includes an insulating layer covering the outside of the second conductive layer, wherein the insulating layer and / or the substrate are made of a transparent material; or,

[0037] The LED light-emitting structure includes a protective layer located outside the second conductive layer, and the protective layer and / or the substrate are made of a transparent material.

[0038] Furthermore, the first conductive layer includes a plurality of color target regions distributed in an array, each color target region including three target regions spaced apart and each carrying an LED chip of a different emitting color.

[0039] Furthermore, the center of gravity of the LED chip is close to the first electrode; the LED chip includes a metal mass block connected to its first electrode; or, the cross-sectional area of ​​the end where the first electrode of the LED chip is located is larger than the cross-sectional area of ​​the end where the second electrode is located.

[0040] Furthermore, the LED chip is in the shape of a cuboid or a cube;

[0041] The LED chip includes two sets of electrode pairs, with the first electrodes of each set of electrode pairs located on two adjacent surfaces of the LED chip; or,

[0042] The LED chip includes three sets of electrode pairs, and the second electrodes of the three sets of electrode pairs are located on three adjacent surfaces of the LED chip.

[0043] Thirdly, the present invention proposes a multi-layer stacked LED light-emitting structure, comprising at least two stacked LED light-emitting structures, wherein the LED chips on the same layer of the LED light-emitting structure emit the same color, and the LED chips on each layer of the LED light-emitting structure emit different colors.

[0044] Compared with existing technologies, the present invention has the following beneficial effects: According to at least one embodiment of the present invention, multiple LED chips are randomly distributed on at least a target area. Each LED chip includes an electrode pair, wherein the electrode pair includes a first electrode and a second electrode respectively located on two opposite surfaces of the LED chip. By randomly distributing the LED chips, the positional accuracy requirements of the LED chips during transfer are reduced, eliminating the need for expensive, high-precision mass transfer equipment, greatly improving production efficiency and reducing production costs. Moreover, there is no need to process invalid LED chips, significantly reducing the difficulty of the process. Attached Figure Description

[0045] Figure 1 This is a cross-sectional schematic diagram of the substrate in some embodiments of the present invention.

[0046] Figure 2 This is a schematic diagram showing the location of the target area on the substrate in some embodiments of the present invention.

[0047] Figure 3 This is a cross-sectional view of a substrate with LED chips in some embodiments of the present invention.

[0048] Figure 4 This is a top view schematic diagram of a target area on a substrate in some embodiments of the present invention where LED chips are randomly distributed.

[0049] Figure 5 This is a three-dimensional schematic diagram of an LED chip according to some embodiments of the present invention.

[0050] Figure 6 These are schematic diagrams of several different orientations of LED chips in some embodiments of the present invention.

[0051] Figure 7 This is a schematic diagram of an LED chip with an external package in some embodiments of the present invention.

[0052] Figure 8 This is a cross-sectional schematic diagram of the LED light-emitting structure in some embodiments of the present invention. In the figure, the second conductive layer is covered by an insulating layer.

[0053] Figure 9 yes Figure 6 The diagram shown illustrates the structure with a second conductive layer added.

[0054] Figure 10 This is a schematic diagram of LED chips in some embodiments of the present invention.

[0055] Figure 11 This is a schematic diagram of LED chips in some embodiments of the present invention.

[0056] Figure 12 This is a schematic diagram of LED chips in some embodiments of the present invention.

[0057] Figure 13 This is a three-dimensional schematic diagram of an LED chip according to some embodiments of the present invention.

[0058] Figure 14 yes Figure 13 The diagram shows the front view of the LED chip.

[0059] Figure 15 This is a three-dimensional schematic diagram of an LED chip according to some embodiments of the present invention.

[0060] Figure 16 This is a schematic diagram of some embodiments of the present invention where the target area carries LED chips of different emitting colors.

[0061] Figure 17 This is a schematic diagram of LED chips randomly distributed across the entire substrate surface in some embodiments of the present invention.

[0062] Figure 18 This is a schematic diagram of a substrate surface array with multiple colored target regions in some embodiments of the present invention.

[0063] Figure 19 This is a cross-sectional schematic diagram of the LED light-emitting structure in some embodiments of the present invention. In the figure, a protective layer is provided outside the second conductive layer.

[0064] Figure 20 This is a schematic diagram showing the positions of row driving lines and column driving lines in some embodiments of the present invention.

[0065] Figure 21 This is a cross-sectional schematic diagram of a multi-layered stacked LED light-emitting structure according to some embodiments of the present invention.

[0066] Figure 22 This is a cross-sectional schematic diagram of a multi-layered stacked LED light-emitting structure according to some embodiments of the present invention. Detailed Implementation

[0067] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0068] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0069] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0070] Some embodiments of the present invention provide a method for fabricating an LED light-emitting structure, which includes the following steps:

[0071] S1. Provide substrate 1, for reference Figure 1 and Figure 2 The surface of the substrate 1 is provided with a first conductive layer 10, which includes a target area 100 for supporting the LED chip 2. Figure 1 In the diagram, the approximate area of ​​the target region 100 is indicated by a cross-sectional line.

[0072] S2. For example Figures 3 to 5 As shown, multiple LED chips 2 are randomly distributed on at least a target area 100. Each LED chip 2 includes an electrode pair, comprising a first electrode 20 and a second electrode 21 located on opposite surfaces of the LED chip 2. One of the first electrode 20 and the second electrode 21 is a positive electrode, and the other is a negative electrode. It is understood that the positions of the first electrode 20 and the second electrode 21 determine the direction of current flow to illuminate the LED chip 2. In some embodiments, the LED chip 2 is a vertically structured LED chip. By using a vertical chip, luminous efficiency can be maintained while significantly reducing the size of the LED chip. It is understood that after the multiple LED chips 2 are randomly distributed on at least the target area 100, the positions and orientations of the multiple LED chips 2 are random, randomly forming LED chips 2 with their first electrode 20 in contact with the target area 100 and LED chips 2 with their first electrode 20 not in contact with the target area 100. Figure 6 The diagram shows the possible orientations of several LED chips 2 when randomly distributed. The LED chip 2 whose first electrode 20 is in contact with the target area 100 is called the effective LED chip 2a, and the remaining LED chips 2 are called the ineffective LED chips 2b.

[0073] S3. For example Figure 7 As shown, a package 3 is provided on the outside of the substrate 1 to cover all the LED chips 2, so as to fix and protect the LED chips 2 on the substrate 1. It can be understood that the package 3 covers not only the active LED chips 2a, but also the inactive LED chips 2b.

[0074] S4. For example Figure 8 As shown, a second conductive layer 11 is prepared on top of the package 3. The second conductive layer 11 is electrically connected to the second electrode 21 of the effective LED chip 2a. It can be understood that, as Figure 9 As shown, the first electrode 20 and the second electrode 21 of the effective LED chip 2a are electrically connected to the target area 100 below it and the second conductive layer 11 above it, respectively. With the cooperation of the first conductive layer 10 and the second conductive layer 11, the effective LED chip 2a is lit. For example, when the first electrode 20 is a positive electrode, a high-level voltage is applied to the first conductive layer 10, and the second conductive layer 11 is grounded or connected to a low level, which can drive the effective LED chip 2a to emit light.

[0075] It is understood that the target area 100 corresponds to the area of ​​the first conductive layer 10 covered by the projection of the second conductive layer 11 along the thickness direction of the substrate 1. The positive and negative electrodes at both ends of the effective LED chip 2a in the target area 100 can be electrically connected to the first conductive layer 10 and the second conductive layer 11 respectively, and can be lit up after being powered on.

[0076] Understandably, although the ineffective LED chip 2b cannot be driven to emit light, as long as there is one luminous LED chip 2 in the target area 100, the target area 100 can achieve the function of emitting light. Furthermore, under constant current source driving conditions, when the forward conduction voltage (Vf) of multiple parallel LED chips is similar, the total current output by the constant current source is approximately evenly distributed among the LED chips. Since the total current is constant, the total luminous power and overall brightness remain unchanged regardless of the number of parallel LED chips. In other words, even if the number of effective LED chips 2a in each target area 100 is different, as long as each target area 100 is driven by a constant current source, the luminous brightness of each target area 100 can be nearly uniform. Of course, more accurate uniformity can be further optimized through algorithms. The more luminous LED chips 2 there are in the target area 100, the more uniform the brightness of the pixels corresponding to that target area will be.

[0077] It is understandable that since there are usually a large number of effective LED chips 2a in the target area 100, such as two, three or more effective LED chips 2a, even if there are damaged LED chips 2, the target area 100 can still emit light normally, which greatly reduces the reliability requirements of the LED chips 2 and increases the process fault tolerance. For example, in a display screen made of an LED light-emitting structure, even if there are damaged LED chips 2 in the target area 100, as long as there is at least one normally emitting LED chip 2, the entire screen can be displayed normally, reducing the possibility of dead pixels on the screen.

[0078] Understandably, by randomly distributing the LED chips 2 across at least the target area 100, the positional requirements for individual LED chips 2 can be significantly reduced, avoiding the high precision requirements of traditional mass transfer. This eliminates the need for expensive, high-precision mass transfer equipment, greatly improving production efficiency and reducing production costs. Furthermore, invalid LED chips 2b can remain in the target area 100 without requiring processing, significantly reducing the complexity of the process.

[0079] LED chip 2 can be a Micro LED chip or a Mini LED chip. Because there is no need for point-to-point mass transfer, the size of LED chip 2 can be made very small, and the cost of a single LED chip 2 is lower. A large number of LED chips 2 can be randomly distributed in a small target area 100, such as a dozen, dozens, hundreds or even more LED chips 2, thereby improving the reliability and uniformity of light emission.

[0080] It is understandable that when a large number of LED chips 2 are randomly distributed, it is almost inevitable that there will be a valid LED chip 2a in the target area 100. In addition, the number of valid LED chips 2a in the target area 100 can be further increased through various means.

[0081] In some embodiments, the center of gravity of the LED chip 2 is set close to the first electrode 20. This makes the LED chip 2 more stable when its first electrode 20 is facing downwards, especially when randomly distributed across at least the target area 100. Therefore, the probability of the first electrode 20 of the LED chip 2 facing downwards is significantly increased. As a possible example, refer to... Figure 10 The LED chip 2 includes a metal mass block 200 connected to its first electrode 20. The center of gravity of the LED chip 2 is changed by adding the metal mass block 200. As a feasible example, such as... Figure 11 As shown, the first electrode 20 of the LED chip 2 is widened and / or thickened to bring its center of gravity closer to the first electrode 20. As a possible example, such as... Figure 12 As shown, the cross-sectional area of ​​the end where the first electrode 20 of the LED chip 2 is located is larger than the cross-sectional area of ​​the end where the second electrode 21 is located, and its overall shape is smaller at the top and larger at the bottom, so that its center of gravity is close to the first electrode 20. It can be understood that the above examples can be used in combination to further ensure the effect.

[0082] In some embodiments, the LED chip 2 is in the shape of a cuboid or a cube, and includes at least two sets of electrode pairs. The first electrode 20 of the two sets of electrode pairs is located on two adjacent surfaces of the LED chip 2. Similarly, each of the two first electrodes 20 is provided with a second electrode 21, and the first electrode 20 and the second electrode 21 of the same electrode pair are located on two opposite surfaces of the LED chip 2. Figure 13 and Figure 14 A schematic diagram is shown when two sets of electrodes are provided on the LED chip 2. Because the number of first electrodes 20 on the surface of the LED chip 2 is increased, the probability of the first electrodes 20 of the LED chip 2 contacting the target area 100 can be significantly increased. Specifically, assuming that the probability of each side of the LED chip 2 facing down is the same, then when the first electrode 20 is provided on only one side and on both sides, the probability of a downward-facing first electrode 20 is one-sixth and one-third, respectively. Optionally, such as... Figure 15 As shown, the LED chip 2 includes three sets of electrode pairs. The first electrode 20 of the three sets of electrode pairs is located on three adjacent surfaces of the LED chip 2. Assuming that the probability of each surface of the LED chip 2 facing down is the same, when three sets of electrode pairs are set, the probability of the first electrode 20 of the LED chip 2 facing down is one in half, which greatly increases the probability. When the number of LED chips 2 randomly distributed in the target area 100 is 10, the probability of having a valid LED chip 2 can be greater than 99.9%. If combined with the aforementioned center of gravity adjustment or other methods, the probability can be further improved. For example, the center of gravity of the LED chip 2 can be set close to one of the first electrodes 20, or it can be set close to the connection position of two or three first electrodes 20.

[0083] Optionally, the surface of the first electrode 20 is provided with conductive adhesive, so that when the first electrode 20 comes into contact with the target area 100, it is less likely to flip or roll, thereby improving the reliability of the contact between the first electrode 20 and the target area 100.

[0084] Understandably, the probability of the first electrode 20 being on the bottom can be increased in other ways. For example, the probability can be increased by applying an external magnetic field: a small amount of magnetic metal can be deposited on the side of the first electrode 20 or unidirectional magnetic particles can be adhered, and a magnetic field can be applied below the substrate 1 to align the LED chips 2 in the correct orientation. Alternatively, the probability can be increased by applying an external sound field or electric field.

[0085] Optionally, each target area 100 carries no fewer than 8 LED chips 2 to increase the probability of a valid LED chip 2a appearing.

[0086] In step S2, the random distribution of LED chips 2 over at least the target area 100 can be achieved in various ways.

[0087] In some embodiments, the LED chips 2 are directly poured onto at least the target area 100. Specifically, a large number of LED chips 2 can be placed in a storage container, and then the LED chips 2 are released into at least the target area 100 through the storage container. Since the posture of the LED chips 2 in the storage container is random, and the randomness of the LED chips 2 is also increased during the falling process, the LED chips 2 are also randomly distributed after falling into the target area 100. Specifically, the position and posture (e.g., the position of the electrodes) of the LED chips 2 are diverse.

[0088] In other embodiments, randomly distributing the LED chips 2 over at least the target area 100 includes the following steps:

[0089] S21. Place multiple LED chips 2 in a liquid to form an LED paste.

[0090] S22. Transfer the LED paste to at least the target area 100.

[0091] It is understandable that the more uniformly the LED chip 2 is distributed in the liquid, the more uniformly the LED chip 2 is distributed in the target area 100 after it is transferred to the target area 100. When the volume of LED paste carried by each target area 100 is similar, the number of LED chips 2 contained in each target area 100 is also relatively similar, which is conducive to increasing the uniformity of light emission.

[0092] Since the orientation of the LED chip 2 in the liquid is random, its position and orientation in the target area 100 are also random after the LED slurry is transferred to the target area 100, resulting in diverse electrode positions. It is understandable that the number of LED chips 2 that may exist in the target area 100 can be controlled by controlling the concentration of the LED chip 2 (i.e., the number of LED chips 2 contained in a unit volume of slurry), thereby controlling the probability of the presence of effective LED chips 2.

[0093] The liquid can be deionized water, an aqueous solution with added surfactants, an organic solvent, or an inert liquid with a density higher than water. Understandably, the liquid does not dissolve, expand, encapsulate, or bond materials, nor does it undergo electrochemical reactions with metals.

[0094] It is understandable that the liquid on substrate 1 can be removed by methods such as solvent evaporation, solution annealing, and capillary drainage. For liquids that can be cured, they can also be cured and retained.

[0095] Optionally, in step S22, the LED paste is transferred to the target area 100 by means of screen printing, embossing, spraying, or printing. During screen printing, the LED paste is embossed onto the target area 100 using a screen mask. During embossing, the LED paste is first applied to a template with openings and then transferred to the target area. During spraying, the LED paste is sprayed onto the surface of the target area. Printing can be, for example, inkjet printing or dispensing printing.

[0096] In some embodiments, the first conductive layer 10 includes a plurality of target regions 100, and all LED chips 2 carried on each target region 100 have the same final emission color. The final emission color refers to the color of the light from all LED chips 2 mixed together. In this case, the LED light-emitting structure is a monochromatic LED light-emitting structure. For example, each target region 100 can carry LED chips 2 of the same color, and the final emission color is the color of the LED chip 2 itself. For example, ... Figure 16 As shown, each target area 100 carries two or three (three in the figure) LED chips 2 with different emitting colors. The emitting color of the LED chips 2 after mixing different emitting colors is consistent, and the mixed emitting color is the final emitting color. In this case, when multiple LED chips 2 are randomly distributed on at least the target area 100, the LED chips 2 can be randomly distributed across the entire upper surface of the substrate 1 (e.g., by the pouring or slurry coating method described above), such as... Figure 17 As shown, since LED chips 2 are randomly distributed across the entire upper surface of substrate 1, LED chips 2 are also randomly distributed across each target area 100. This further reduces the requirement for distribution accuracy. Of course, multiple LED chips 2 can also be randomly distributed only within the area corresponding to the target area 100 (e.g., by screen printing) to reduce waste of LED chips 2. Since the final emitted color is the same, it can be printed in one step.

[0097] In some embodiments, the first conductive layer 10 includes a plurality of target regions 100, and the LED chip 2 carried in each target region 100 has the same emission color. The LED chip 2 carried in different target regions 100 does not have the same emission color. For example, there are two or three target regions among the first color target region 100a for carrying the first color LED chip 2, the second color target region 100b for carrying the second color LED chip 2, and the third color target region 100c for carrying the third color LED chip 2. In this case, the LED chip 2 of the corresponding emission color can be randomly distributed in the target regions 100 of different colors in stages, instead of being randomly distributed on the entire surface of the substrate 1. For example, by means of screen printing or inkjet printing, the LED chips 2 of the corresponding light-emitting colors are randomly distributed in three stages in the first color target area 100a, the second color target area 100b, and the third color target area 100c. Specifically, the first color LED chips 2 are printed on all the first color target areas 100a first, then the second color LED chips 2 are printed on all the second color target areas 100b, and then the third color LED chips 2 are printed on all the third color target areas 100c (of course, the order can be adjusted). When randomly scattering LED chips 2 of a certain color by tilting, an auxiliary plate can be set up to block target areas that do not correspond to that color of LED chip 2. The auxiliary plate can be configured to only expose the corresponding target area, ensuring that the LED chip 2 is reliably scattered in the desired area. For example, when scattering the first-color LED chip 2 in the first-color target area 100a, the auxiliary plate can expose the entire first-color target area 100a while blocking other areas. This way, when tilting the first-color LED chip 2, it will not be mistakenly located in the second-color target area 100b or the third-color target area 100c. For tilting other colors of LED chips 2, the corresponding auxiliary plate can be used.

[0098] Optionally, of the first-color LED chip 2, the second-color LED chip 2, and the third-color LED chip 2, one is used to emit red light, one is used to emit green light, and one is used to emit blue light, for example, emitting red light, green light, and blue light respectively. In the figure, the LED chips 2 marked with the letters R, G, and B represent the first-color LED chip, the second-color LED chip, and the third-color LED chip, respectively.

[0099] In some embodiments, step S2, after randomly distributing the plurality of LED chips 2 on at least the target area 100, may further include the following step: applying vibration to the substrate 1 so that the LED chips 2 can reliably contact the target area 100, thereby reducing the possibility of LED chip 2 stacking.

[0100] In some embodiments, to improve the reliability of the electrical connection between the LED chip 2 and the target region 100, the metal layers of the first electrode 20 and the target region 100 can be melted by heating, so that they can be welded together. For example, a metal layer with a relatively low melting point can be provided on the first electrode 20 and the target region 100 to facilitate welding, while the second electrode 21 can be made of a metal with a higher melting point to prevent the second electrode 21 from melting during welding of the first electrode 20 and the target region 100. Of course, those skilled in the art can also ensure the reliability of the electrical connection between the effective LED chip 2a and the target region 100 in other ways.

[0101] In some embodiments, the substrate 1 is glass, silicon wafer, ceramic, or a thin film. The thin film is made of an insulating material, such as polyimide (PI, Kapton), polyester film (PET, Mylar), polycarbonate (PC), or polyethylene terephthalate (PEN). The first conductive layer 10 can be, for example, a metal conductive layer, ITO, or a metal mesh. Optionally, both the substrate 1 and the first conductive layer 10 are made of transparent materials.

[0102] It is understandable that a conductive adhesive layer such as silver paste, conductive glue, or solder paste may be provided between the second conductive layer 11 and the second electrode 21, depending on the needs of the fabrication process.

[0103] In some embodiments, step S3 further includes the following step: thinning the upper surface of the package 3 (e.g., by grinding) to expose the second electrode 21 of the LED chip 2. This ensures that the top electrode of the LED chip 2 can be reliably electrically connected to the second conductive layer 11 during the fabrication of the second conductive layer 11. Optionally, the initial thickness of the second electrode 21 (the thickness before thinning) is not less than 10 μm, so that after the thinning process, as many, or even all, of the second electrodes 21 of the effective LED chips 2a can be reliably exposed, ensuring electrical connection with the second conductive layer 11. It is understood that if the top surface of the LED chip 2 can be reliably exposed during the fabrication of the package 3, the step of thinning the package 3 can be omitted.

[0104] In some embodiments, such as Figure 8 As shown, in step S4, when the second conductive layer 11 is formed above the package 3, an insulating layer 12 is also formed to cover the second conductive layer 11. The insulating layer 12 can protect the second conductive layer 11. The second conductive layer 11 and the insulating layer 12 can be fabricated, for example, by an RDL process. Optionally, the insulating layer 12 and / or the substrate 1 are made of a transparent material so that light can be emitted normally. In other embodiments, such as Figure 19As shown, step S4 further includes the following step: A protective layer 13 is prepared on the outside of the second conductive layer 11 to protect the second conductive layer 11. The protective layer 13 can be, for example, glass or a thin film. Optionally, the insulating layer 12 and / or the substrate 1 are made of a transparent material to allow light to be emitted normally.

[0105] It is understood that the first conductive layer 10 may include only one target region 100 or more target regions 100. Optionally, each target region 100 can independently drive the effective LED chip 2a on each target region 100 to emit light. Furthermore, the current magnitude of each target region 100 can be independently controlled, which is beneficial for regulating the luminous brightness of each target region 100.

[0106] like Figure 18 and Figure 20 As shown, the LED light-emitting structure includes multiple arrayed target regions 100, specifically in a three-row, three-column configuration. The first conductive layer 10 includes multiple column driving lines 101, and the second conductive layer 11 includes multiple row driving lines 111. The column driving lines 101 and row driving lines 111 are staggered, generally perpendicular to each other. As mentioned above, the target regions 100 correspond to the overlapping portions of the column driving lines 101 and row driving lines 111 in the top-view direction, and the target regions 100 are a part of the column driving lines 101. By applying a positive voltage to the LED chip 2 within the target regions 100 that need to emit light through the cooperation of the column driving lines 101 and row driving lines 111, independent driving of each target region 100 can be achieved.

[0107] In some embodiments, the first conductive layer 10 includes at least three spaced target regions 100, each of which can be independently driven by an effective LED chip 2a. In step S2, when the LED chips 2 are randomly distributed on at least the target regions 100, three different LED chips 2 of different emission colors are sequentially transferred to the three target regions 100, and the three adjacent target regions 100 of different emission colors form a colored target region 14. Figure 18 The approximate area of ​​the colored target region 14 is outlined with a double-dotted line. It is understood that the first conductive layer 10 may include a large number of arrayed colored target regions 14 to form a display panel. When the first electrode 20 is a positive electrode, the three column driving lines 101 and one row driving line 111 can drive the three target regions 100 of the colored target region 14 to emit light independently.

[0108] When the first conductive layer 10 includes two or more colored target areas 14, when multiple LED chips 2 are randomly distributed on at least the target area 100 in step S2, LED chips 2 of the same color can be printed on the corresponding target area 100 in three separate printing operations using screen printing. For example, the first color LED chip 2 is printed on all the target areas 100 where the first color LED chip 2 needs to be placed, the second color LED chip 2 is printed on all the target areas 100 where the second color LED chip 2 needs to be placed, and the third color LED chip 2 is printed on all the target areas 100 where the third color LED chip 2 needs to be placed.

[0109] Some embodiments of the present invention propose an LED light-emitting structure, which can be prepared using the LED light-emitting structure preparation method described above.

[0110] like Figure 8 and Figure 19 As shown, the LED light-emitting structure includes a substrate 1, an LED chip group, a package 3, and a second conductive layer 11.

[0111] The surface of the substrate 1 is provided with a first conductive layer 10, which includes a target area 100.

[0112] An LED chip set comprises multiple LED chips 2 randomly distributed across at least a target area 100; in other words, all LED chips 2 in the target area 100 constitute an LED chip set. It is understood that because the LED chips 2 are randomly distributed across at least the target area 100, the position and orientation of each LED chip 2 in the target area 100 (e.g., the orientation of the electrodes is random) are not regular. As mentioned above, each LED chip 2 includes an electrode pair, comprising a first electrode 20 and a second electrode 21. At least one first electrode 20 of an LED chip 2 is in contact with the target area 100. LED chips 2 whose first electrode 20 is in contact with the target area 100 are referred to as effective LED chips 2a, and the remaining LED chips 2a are referred to as ineffective LED chips 2b. As mentioned above, the target area 100 can still emit light normally when there is only one effective LED chip 2a; even with two or more LED chips 2a, the target area 100 can still emit light normally even if there are abnormal LED chips 2.

[0113] The package 3 covers the outside of all LED chips 2, and the second electrode 21 of the effective LED chip 2a is exposed from the top surface of the package 3.

[0114] The second conductive layer 11 is electrically connected to the second electrode 21 of the effective LED chip 2.

[0115] The method by which LED chips 2 are randomly distributed on at least the target area 100 and the structure of LED chips 2 can be referred to the description above, and will not be repeated here.

[0116] In some embodiments, the substrate 1 is glass, silicon wafer, ceramic, or thin film, and the first conductive layer 10 is a metal conductive layer, ITO, or metal mesh.

[0117] In some embodiments, such as Figure 8 As shown, the LED light-emitting structure includes an insulating layer 12 covering the outside of the second conductive layer 11. In other embodiments, such as Figure 19 As shown, the LED light-emitting structure includes a protective layer 13 located outside the second conductive layer 11. The protective layer 13 can be glass or a thin film. The material of the thin film can be, for example, polyimide (PI, Kapton), polyester film (PET, Mylar), polycarbonate (PC), or polyethylene terephthalate (PEN).

[0118] It is understandable that when the substrate 1, the package 3, the insulating layer 12, and the protective layer 13 are all made of transparent materials, and the first conductive layer 10 and the second conductive layer 11 are made of transparent materials or have a thinner line width, the LED light-emitting structure as a whole is transparent and can be used as a transparent display screen for double-sided display.

[0119] It is understandable that, depending on the randomly distributed area, the LED light-emitting structure may have LED chips 2 only at the position corresponding to its target area 100, or it may have LED chips 2 distributed evenly on the entire surface of the substrate 1.

[0120] In some embodiments, such as Figure 17 As shown, the LED light-emitting structure includes multiple arrayed target areas 100. Each target area 100 is equipped with three different LED chips 2 emitting colors, meaning that LED chips 2 emitting a first color, a second color, and a third color are present simultaneously. The final emitted color of the target area 100, i.e., the color of the panel light source, can be adjusted by changing the proportion of the different colored LED chips 2. Furthermore, if the LED light-emitting structure is made into a white panel, the color temperature can be adjusted, resulting in lower cost and simpler manufacturing process compared to traditional white backlight panels using blue light and blue phosphor. Moreover, the brightness of each pixel is controllable, achieving high brightness consistency across the entire backlight panel.

[0121] In some embodiments, such as Figure 18As shown, the first conductive layer 10 includes a plurality of color target regions 14 arranged in an array. Each color target region 14 includes three target regions 100 spaced apart. The LED chips 2 on the three target regions 100 belonging to a color target region 14 emit different colors. For example, the LED chip 2 on the first target region 100 emits light of the first color, the LED chip 2 on the second target region 100 emits light of the second color, and the LED chip 2 on the third target region 100 emits light of the third color. By controlling the emission of LED chips 2 on different target regions 100, multiple colors can be obtained. The first color, the second color, and the third color can be, for example, red, green, and blue, respectively.

[0122] This invention also proposes a multi-layer stacked LED light-emitting structure, which includes at least two layers of LED light-emitting structures. Each layer of LED light-emitting structure can be prepared using the LED light-emitting structure preparation method described above, and its structure can also refer to the LED light-emitting structure described above. The LED chips 2 located on the same layer of LED light-emitting structure emit the same color, and the LED chips 2 on each layer of LED light-emitting structure emit different colors.

[0123] Figure 21 and Figure 22 In the illustrated embodiment, the multi-layered LED light-emitting structure includes a first layer LED light-emitting structure 40, a second layer LED light-emitting structure 41, and a third layer LED light-emitting structure 42 stacked together. Specifically, the first layer LED light-emitting structure 40, the second layer LED light-emitting structure 41, and the third layer LED light-emitting structure 42 are stacked together sequentially from bottom to top. The LED chips 2 on the three layers of LED light-emitting structures emit different colors, for example, they can emit red, green, and blue light respectively.

[0124] like Figure 21 As shown, the projections of the target areas 100 of the three-layer LED light-emitting structure in the stacking direction can overlap, and the three overlapping target areas 100 constitute a color target area 14. The multi-layer stacked LED light-emitting structure may include only one color target area 14, in which case the multi-layer stacked LED light-emitting structure can be used as an LED lamp bead. The multi-color LED light-emitting structure may also include multiple arrayed color target areas 14, so that it can be used as a display screen or other display device.

[0125] like Figure 22As shown, the projections of the target regions 100 of the three-layer LED light-emitting structure in the stacking direction can be non-overlapping. In this case, the projections of the target regions 100 of the three LED light-emitting structures in the stacking direction are arranged sequentially at intervals. Three adjacent target regions of the three-layer LED light-emitting structure constitute a colored target region 14. Similarly, a multi-layer stacked LED light-emitting structure can include only one colored target region 14, or it can include multiple arrayed colored target regions 14.

[0126] It is understandable that when the target areas overlap, the light mixing effect is better, and when they do not overlap, the upper LED light-emitting structure can avoid blocking the light emitted by the lower LED light-emitting structure, thus increasing the output brightness.

[0127] It is understood that other embodiments or structural details of the LED light-emitting structure can be found in the description above, and will not be repeated here.

[0128] It is understood that the positions, dimensions, and quantities of the target areas, LED chips, and other structures shown in the accompanying drawings are illustrative and do not represent the actual form of the product. For example, the number of target areas and LED chips may be fewer or more.

[0129] It should be noted that, in the absence of conflict, the various embodiments described herein can be combined with each other to obtain more implementation schemes.

[0130] The above are merely specific embodiments of the present invention, and any improvements made based on the concept of the present invention shall be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an LED light-emitting structure, characterized in that, Includes the following steps: S1. Provide a substrate (1), the surface of which is provided with a first conductive layer (10), the first conductive layer (10) including a target area (100); S2. A plurality of LED chips (2) are randomly distributed on at least the target area (100). Each LED chip (2) includes an electrode pair, which includes a first electrode (20) and a second electrode (21) located on opposite surfaces of the LED chip (2). After the plurality of LED chips (2) are randomly distributed on at least the target area (100), LED chips (2) whose first electrode (20) is in contact with the target area (100) and LED chips (2) whose first electrode (20) is not in contact with the target area (100) are randomly formed. The LED chips (2) whose first electrode (20) is in contact with the target area (100) are called effective LED chips (2a), and the remaining LED chips (2) are called ineffective LED chips (2b). S3. A package (3) covering all the LED chips (2) is provided on the outside of the substrate (1); S4. A second conductive layer (11) is prepared on top of the package (3), and the second conductive layer (11) is electrically connected to the second electrode (21) of the effective LED chip (2a).

2. The method for preparing the LED light-emitting structure as described in claim 1, characterized in that, In step S2, each target area (100) carries no less than 8 LED chips (2).

3. The method for preparing the LED light-emitting structure as described in claim 1, characterized in that, In step S2, randomly distributing the plurality of LED chips (2) on at least the target area (100) includes the following steps: S21. Place multiple LED chips (2) in a liquid to form an LED paste; S22. Transfer the LED paste to at least the target area (100).

4. The method for preparing the LED light-emitting structure as described in claim 3, characterized in that, In step S22, the LED paste is transferred to the target area (100) by screen printing, embossing, spraying, or printing.

5. The method for preparing the LED light-emitting structure as described in claim 1, characterized in that, In step S4, when the second conductive layer (11) is formed above the package (3), an insulating layer (12) covering the second conductive layer (11) is also formed. The insulating layer (12) and / or the substrate (1) are made of a transparent material; or, Step S3 further includes the following step: preparing a protective layer on the outside of the second conductive layer (11), wherein the protective layer and / or the substrate (1) are made of a transparent material.

6. The method for preparing the LED light-emitting structure as described in claim 1, characterized in that, Step S3 further includes the following step: thinning the upper surface of the package (3) to expose the second electrode (21) of the LED chip (2).

7. The method for preparing the LED light-emitting structure as described in claim 1, characterized in that, The first conductive layer (10) includes a plurality of target regions (100), all of which are used to carry LED chips (2) of the same emission color or each of the target regions (100) is used to carry LED chips (2) of two or three different emission colors.

8. The method for preparing the LED light-emitting structure as described in claim 1, characterized in that, In step S2, when multiple LED chips (2) are randomly distributed on at least the target area (100), multiple LED chips (2) are randomly distributed on the entire surface of the substrate (1), or multiple LED chips (2) are randomly distributed only within the range corresponding to the target area (100).

9. The method for preparing the LED light-emitting structure as described in claim 1, characterized in that, The first conductive layer (10) includes two or three target regions, namely, a first color target region for carrying a first color LED chip, a second color target region for carrying a second color LED chip, and a third color target region for carrying a third color LED chip. In step S2, when the LED chips (2) are randomly scattered on at least the target regions (100), the LED chips (2) of the corresponding light emission colors are randomly scattered in the target regions carrying LED chips of different light emission colors in several batches.

10. The method for preparing the LED light-emitting structure as described in claim 1, characterized in that, In step S2, when the LED chips (2) are randomly scattered on at least the target area (100), two or three different LED chips (2) with different light emission colors are also randomly scattered on at least the target area (100).

11. The method for preparing an LED light-emitting structure according to any one of claims 1 to 10, characterized in that, The center of gravity of the LED chip (2) is close to the first electrode (20).

12. The method for preparing the LED light-emitting structure as described in claim 11, characterized in that, The LED chip (2) includes a metal mass block connected to its first electrode.

13. The method for preparing the LED light-emitting structure as described in claim 11, characterized in that, The cross-sectional area of ​​the end where the first electrode (20) of the LED chip (2) is located is greater than the cross-sectional area of ​​the end where the second electrode (21) is located.

14. The method for preparing an LED light-emitting structure according to any one of claims 1 to 10, characterized in that, The LED chip (2) is in the shape of a cuboid or a cube; The LED chip (2) includes two sets of electrode pairs, with the first electrode (20) of each set of electrode pairs located on two adjacent surfaces of the LED chip (2); or, The LED chip (2) includes three sets of electrode pairs, and the first electrode (20) of the three sets of electrode pairs is located on three adjacent surfaces of the LED chip (2).

15. An LED light-emitting structure, characterized in that, include: A substrate (1) has a first conductive layer (10) on its surface, the first conductive layer (10) including a target area (100). Multiple LED chips (2) are randomly distributed on at least the target area (100). Each LED chip (2) includes an electrode pair, which includes a first electrode (20) and a second electrode (21) located on opposite surfaces of the LED chip (2). The position and orientation of the LED chips (2) are random. One or more of the first electrodes (20) of the LED chips (2) are in contact with the target area (100). The LED chips (2) whose first electrodes (20) are in contact with the target area (100) are called effective LED chips (2a), and the remaining LED chips (2) are called ineffective LED chips (2b). The package (3) covers the exterior of all the LED chips (2), and the second electrode (21) of the LED chips (2) is exposed from the top surface of the package (3); as well as, The second conductive layer (11) is electrically connected to the second electrode (21) of the effective LED chip (2a).

16. The LED light-emitting structure as described in claim 15, characterized in that, The LED light-emitting structure includes an insulating layer (12) covering the outside of the second conductive layer (11), wherein the insulating layer (12) and / or the substrate (1) are made of a transparent material; or, The LED light-emitting structure includes a protective layer (13) located outside the second conductive layer (11), and the protective layer and / or the substrate (1) are made of a transparent material.

17. The LED light-emitting structure as described in claim 15, characterized in that, The first conductive layer (10) includes multiple colored target regions distributed in an array, each colored target region including three target regions (100) spaced apart and each carrying an LED chip (2) of a different color.

18. The LED light-emitting structure according to any one of claims 15 to 17, characterized in that, The center of gravity of the LED chip (2) is close to the first electrode (20); the LED chip (2) includes a metal mass block connected to its first electrode; or, the cross-sectional area of ​​the end where the first electrode (20) of the LED chip (2) is located is greater than the cross-sectional area of ​​the end where the second electrode (21) is located.

19. The LED light-emitting structure according to any one of claims 15 to 17, characterized in that, The LED chip (2) is in the shape of a cuboid or a cube; The LED chip (2) includes two sets of electrode pairs, with the first electrode (20) of each set of electrode pairs located on two adjacent surfaces of the LED chip (2); or, The LED chip (2) includes three sets of electrode pairs, and the second electrodes (21) of the three sets of electrode pairs are located on three adjacent surfaces of the LED chip (2).

20. A multi-layered stacked LED light-emitting structure, characterized in that, It includes at least two stacked LED light-emitting structures, wherein the LED light-emitting structure is the LED light-emitting structure described in claims 15, 16, 18 or 19, wherein the LED chips (2) on the same layer of the LED light-emitting structure have the same light-emitting color, and the LED chips (2) on each layer of the LED light-emitting structure have different light-emitting colors.

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