Method for transferring LED chips

Abstract

The application relates to the technical field of display arrays, and discloses a transfer method of an LED chip, which comprises the following steps: providing a substrate, putting a solution mixed with LED chips into the substrate, heating to evaporate the solution, and placing the LED chips on the substrate to complete the transfer. The solution is freely flowed on the substrate by putting the solution mixed with the LED chips into the substrate provided with the electrodes arranged at intervals, the LED chips are randomly moved, the LED chips are deposited on the substrate after the solution is evaporated, the LED chips can be basically uniformly distributed, the distance between the two electrodes of the LED chip is greater than the minimum distance between any two adjacent electrodes on the substrate, and the two electrodes of the two LED electrodes fall on different electrodes and are electrically contacted with the maximum probability, the transfer process is completed, and the whole manufacturing process is simple.

Description

Technical Field

[0001] This application belongs to the field of display array technology, and in particular relates to a method for transferring LED (Light Emitting Diode, LED) chips. Background Technology

[0002] Miniature LED display technology is an advanced display technology with advantages such as high brightness, wide color gamut, low power consumption, wide viewing angle, high contrast, high color saturation, and high response rate. Transfer technology is a crucial process in the fabrication of miniature LED display arrays and also a significant bottleneck for the commercialization of miniature LEDs. Current transfer methods, such as those requiring the application of power to align the LED chips, suffer from complex processes and high costs. Summary of the Invention

[0003] The purpose of this application is to provide a method for transferring LED chips, which aims to solve the problems of complex processes and high costs associated with traditional transfer technologies.

[0004] This application provides a method for transferring an LED chip, comprising:

[0005] A substrate is provided, and a solution containing LED chips is placed into the substrate. The substrate is provided with a plurality of electrode units, each electrode unit including a plurality of substrate electrodes. The LED chip includes a chip body and two chip electrodes spaced apart on the chip body. The distance between the two chip electrodes of the LED chip is greater than the minimum distance between any two adjacent substrate electrodes.

[0006] The solution is heated to evaporate, thereby placing the LED chip on the substrate.

[0007] In one embodiment, the solution is further mixed with photoresist, and after the heating to evaporate the solution, an LED chip placed on the substrate is coated with a photoresist layer.

[0008] In one embodiment, the transfer method further includes:

[0009] The photoresist coating on the two chip electrodes of the LED chip and between adjacent LED chips is removed by exposure.

[0010] A metal layer is formed on the LED chip and the substrate by metal deposition.

[0011] The photoresist deposited on the LED chip is removed, and a metal connection is formed between the two chip electrodes of the LED chip and the corresponding substrate electrodes.

[0012] In one embodiment, the solution further contains metal ions, and the heating to evaporate the solution includes:

[0013] The solution is pre-evaporated to evaporate a portion of the solution;

[0014] Electroplating is used to cover the two chip electrodes of the LED chip and the substrate electrode with a metal layer.

[0015] Evaporate the remaining solution.

[0016] In one embodiment, the solution is mixed with flux, and the substrate is also coated with soldering material, wherein heating to evaporate the solution includes:

[0017] The solution is subjected to a first-stage evaporation process;

[0018] The substrate is heated to fuse the two chip electrodes of the LED chip, the substrate electrodes, and the welding material.

[0019] Evaporate the remaining solution to dryness.

[0020] In one embodiment, the substrate is provided with several regions, each region corresponding to one of the electrode units, and the step of placing the solution containing the LED chip into the substrate includes:

[0021] The solution is then placed into each of the aforementioned regions.

[0022] In one embodiment, the solution is mixed with photoresist, and before the solution is placed into each of the regions, the method further includes:

[0023] Print light conversion material into the area;

[0024] The heating to evaporate the solution includes:

[0025] The solution is heated to evaporate it, and the outer surface of the LED chip is coated with photoresist and the light conversion material.

[0026] In one embodiment, the region includes an R electrode region, a G electrode region, and a B electrode region; the printing of the light conversion material into the region includes:

[0027] The light conversion material is printed onto the R electrode region and the G electrode region, respectively.

[0028] The heating to evaporate the solution includes:

[0029] The solution is heated to evaporate it. The outer surfaces of the LED chips in the R electrode region and the G electrode region are coated with the photoresist and the light conversion material, and the outer surface of the LED chip in the B electrode region is coated with the photoresist.

[0030] In one embodiment, after heating to evaporate the solution, the process further includes:

[0031] The photoresist between the two chip electrodes of the LED chip and between adjacent LED chips is removed by exposure.

[0032] A metal layer is formed between the two chip electrodes of the LED chip and the electrodes in the electrode region by metal deposition.

[0033] In one embodiment, the solution includes a first solution, a second solution, and a third solution. The first solution further contains a first light conversion material, photoresist, and metal ions. The second solution contains a second light conversion material, photoresist, and metal ions. The third solution further contains photoresist and metal ions. The region includes an R electrode region, a G electrode region, and a B electrode region. Placing the substrate with the solution containing the LED chip includes:

[0034] The first solution is placed into the R electrode region;

[0035] The second solution is placed into the G electrode region;

[0036] The third solution is placed into the B electrode region.

[0037] In one embodiment, the heating to evaporate the solution includes:

[0038] The solution is pre-evaporated to evaporate a portion of the solution;

[0039] Electroplating is used to cover the two chip electrodes of the LED chip and the substrate electrode with a metal layer.

[0040] The remaining solution is evaporated by heating.

[0041] In one embodiment, the two chip electrodes of the LED chip are respectively wrapped around the two ends of the chip body.

[0042] In one embodiment, the plurality of substrate electrodes includes a first substrate electrode and a second substrate electrode, wherein the first substrate electrode and the second substrate electrode on the substrate are arranged alternately in the longitudinal direction and alternately in the transverse direction.

[0043] In one embodiment, the cross-sectional shape of the first substrate electrode and the second substrate electrode is an equilateral triangle, the ratio of the minimum distance between the first substrate electrode and the second substrate electrode to the side length of the equilateral triangle is in the range of 0.005 to 0.05, and the ratio of the side length of the equilateral triangle to the distance between the two chip electrodes of the LED chip is in the range of 0.1 to 1.

[0044] In one embodiment, the cross-sectional shape of the first substrate electrode and the second substrate electrode is square, the ratio of the minimum distance between the first substrate electrode and the second substrate electrode to the side length of the square is in the range of 0.01 to 0.1, and the ratio of the side length of the square to the distance between the two chip electrodes of the LED chip is in the range of 0.2 to 1.4.

[0045] In one embodiment, the cross-sectional shape of the first substrate electrode and the second substrate electrode is square, and the spacing between the two chip electrodes of the LED chip is less than the sum of the side length of the square and the minimum distance between the first substrate electrode and the second substrate electrode.

[0046] In one embodiment, the minimum spacing between adjacent electrode units is equal to the minimum distance between the first substrate electrode and the second substrate electrode between the electrode units.

[0047] In one embodiment, the plurality of substrate electrodes further includes a third substrate electrode, wherein any one of the first substrate electrode, the second substrate electrode, and the third substrate electrode on the substrate is adjacent to the other two substrate electrodes.

[0048] In one embodiment, the cross-sectional shape of the first substrate electrode, the second substrate electrode, and the third substrate electrode is circular. The ratio of the minimum distance between the first substrate electrode and the second substrate electrode to the diameter of the circle is in the range of 0.01 to 0.1, and the ratio of the diameter of the circle to the distance between the two chip electrodes of the LED chip is in the range of 0.6 to 2.

[0049] In one embodiment, the cross-sectional shape of the first substrate electrode, the second substrate electrode, and the third substrate electrode is a regular hexagon. The ratio of the minimum distance between the first substrate electrode and the second substrate electrode to the side length of the regular hexagon is in the range of 0.05 to 0.2. The ratio of the side length of the regular hexagon to the distance between the two chip electrodes of the LED chip is in the range of 0.2 to 2.

[0050] In one embodiment, the minimum distance between the first substrate electrode, the second substrate electrode, and the third substrate electrode in the electrode unit is the same, and the minimum spacing between adjacent electrode units is equal to the minimum distance between the first substrate electrode and the second substrate electrode in the electrode unit.

[0051] In one embodiment, a pair of finite grooves are formed in two adjacent substrate electrodes, from the middle of one electrode toward the middle of the other electrode.

[0052] In one embodiment, the sum of the length of the limiting groove pair and the minimum distance between two adjacent substrate electrodes is 1.05 to 1.3 times the distance between the two chip electrodes of the LED chip.

[0053] In one embodiment, the solution comprises one or more of deionized water, toluene, xylene, methanol, ethanol, and isopropanol.

[0054] In one embodiment, the chip body is a cylinder, and the two chip electrodes are spaced apart on the side of the cylinder.

[0055] In one embodiment, the chip electrode has a ring-shaped structure, and the difference between the outer diameter of the chip electrode and the radius of the chip body is greater than 0 and less than 3 mm.

[0056] In one embodiment, the spacing between the two chip electrodes is equal to the difference between the distance between the two ends of the chip body and the width between the two chip electrodes.

[0057] In one embodiment, the chip body is a cylinder, and the two chip electrodes are spaced apart at the two ends of the cylinder, with the distance between the chip electrodes being equal to the distance between the two ends of the cylinder.

[0058] In one embodiment, the chip body is a cylinder, and the two chip electrodes respectively cover the ends of the cylinder.

[0059] In one embodiment, the chip body is a prism, and the two chip electrodes are spaced apart on the side of the prism. The chip electrodes include multiple chip sub-electrodes, the number of which is equal to the number of side edges of the prism. Each chip sub-electrode protrudes from one side of the chip body, forming a corresponding annular array.

[0060] The above-mentioned LED chip transfer method involves immersing a solution containing LED chips onto a substrate with spaced electrodes. The solution flows freely on the substrate, causing the LED chips to move randomly. After the solution evaporates, the LED chips are deposited on the substrate. This allows the LED chips to be distributed almost uniformly, and the distance between the two chip electrodes of the LED chip is greater than the minimum distance between any two adjacent electrodes on the substrate. Furthermore, there is the highest probability that the two chip electrodes of the two LEDs will fall onto different electrodes and make electrical contact, thus completing the transfer process. The entire manufacturing process is simple and low-cost. Attached Figure Description

[0061] Figure 1 This is a schematic diagram of the structure of an LED chip in an embodiment of this application;

[0062] Figure 2 This is a schematic diagram of the structure of another LED chip in an embodiment of this application;

[0063] Figure 3A This is a schematic diagram of the structure of a substrate with square electrodes in an embodiment of this application;

[0064] Figure 3B This is a schematic diagram of the structure of transferring the LED chip to a substrate with square electrodes in an embodiment of this application;

[0065] Figure 4A This is a schematic diagram of the structure of a substrate with equilateral triangular electrodes in an embodiment of this application;

[0066] Figure 4B This is a schematic diagram of the structure of transferring the LED chip to a substrate with equilateral triangular electrodes in an embodiment of this application;

[0067] Figure 5A This is a schematic diagram of the structure of a substrate with regular hexagonal electrodes in an embodiment of this application;

[0068] Figure 5B This is a schematic diagram of the structure of transferring the LED chip to a substrate with regular hexagonal electrodes in an embodiment of this application;

[0069] Figure 6A This is a schematic diagram of the structure of a substrate with circular electrodes in an embodiment of this application;

[0070] Figure 6B This is a schematic diagram of the structure of transferring the LED chip to a substrate with circular electrodes in an embodiment of this application;

[0071] Figure 7 This is a cross-sectional schematic diagram of a pixel structure with two types of electrodes in an embodiment of this application;

[0072] Figure 8This is a cross-sectional schematic diagram of a pixel structure with three types of electrodes in an embodiment of this application;

[0073] Figure 9 for Figure 7 The circuit diagram of the driving circuit in the pixel structure is shown.

[0074] Figure 10 for Figure 8 The circuit diagram of the driving circuit in the pixel structure is shown.

[0075] Figure 11 This is a cross-sectional structural diagram of a pixel structure with two types of multi-electrodes in an embodiment of this application;

[0076] Figure 12 This is a cross-sectional structural diagram of a pixel structure with three types of multi-electrodes in an embodiment of this application;

[0077] Figure 13A for Figure 11 A top view of the electrode layer in the pixel structure is shown.

[0078] Figure 13B for Figure 11 The diagram shown is a top view of the electrode line layer in the pixel structure.

[0079] Figure 14A for Figure 12 A top view of the electrode layer in the pixel structure is shown.

[0080] Figure 14B for Figure 12 The diagram shown is a top view of the electrode line layer in the pixel structure.

[0081] Figure 15 This is a schematic diagram of a split layout structure of the pixel structure in an embodiment of this application;

[0082] Figure 16 This is a schematic diagram of a stacked layout structure of pixel structures in an embodiment of this application;

[0083] Figure 17 for Figure 9 The current timing diagram of the power supply line of the drive circuit is shown.

[0084] Figure 18 for Figure 10 The current timing diagram of the power supply line of the drive circuit is shown.

[0085] Figure 19 This is a flowchart of the LED chip transfer method in the embodiments of this application;

[0086] Figure 20 This is a schematic diagram of the cross-sectional structure of the electrode on the substrate in an embodiment of this application;

[0087] Figure 21A This is a schematic diagram of the structure of two types of electrodes with limiting grooves in the embodiments of this application;

[0088] Figure 21B This is a schematic diagram of the structure of the three types of electrodes with limiting grooves in the embodiments of this application;

[0089] Figure 22 This is a flowchart of the LED chip transfer method in the embodiments of this application;

[0090] Figure 23 This is a schematic diagram of the process of selectively placing LED chips into a solution in the LED chip transfer method of this application embodiment;

[0091] Figure 24 This is a schematic diagram illustrating the process of indiscriminately placing the LED chip into the solution in the transfer method of this application embodiment;

[0092] Figure 25 This is a schematic diagram of the evaporation solution process for the first and second schemes to enhance the connection strength between the electrode and the LED chip in the embodiments of this application;

[0093] Figure 26 This is a schematic diagram of the photolithography process for a second method to enhance the connection strength between the electrode and the LED chip in this application embodiment;

[0094] Figure 27 This is a schematic diagram of the photoresist removal process in the second method of strengthening the connection between the electrode and the LED chip in this application embodiment;

[0095] Figure 28 This is a schematic diagram of the metal deposition process for the second method of strengthening the connection between the electrode and the LED chip in the embodiments of this application;

[0096] Figure 29 This is a schematic diagram of the process of removing all photoresist in the second scheme for strengthening the connection between the electrode and the LED chip in this application embodiment;

[0097] Figure 30 This is a schematic diagram of the process of removing all photoresist in the second scheme for strengthening the connection between the electrode and the LED chip in this application embodiment;

[0098] Figure 31 This is a schematic diagram of the first stage of the evaporation solution process for the third method to enhance the connection strength between the electrode and the LED chip in the embodiments of this application;

[0099] Figure 32 This is a schematic diagram of the welding process for the third method of strengthening the connection between the electrode and the LED chip in the embodiments of this application.

[0100] Figure 33 This is a schematic diagram of the electroplating process for the fourth method of strengthening the connection between the electrode and the LED chip in the embodiments of this application;

[0101] Figure 34 This is a schematic diagram of the evaporation solution process for the first scheme of light emission color conversion in the embodiments of this application;

[0102] Figure 35 This is a schematic diagram of the photolithography process for the first scheme of light emission color conversion in the embodiments of this application;

[0103] Figure 36 This is a schematic diagram of the photoresist removal process for the first scheme of light emission color conversion in the embodiments of this application;

[0104] Figure 37 This is a schematic diagram of the metal deposition process for the first scheme of light emission color conversion in the embodiments of this application;

[0105] Figure 38 This is a schematic diagram of the metal deposition process for the first scheme of light emission color conversion in the embodiments of this application;

[0106] Figure 39 This is a schematic diagram of the second stage evaporation process of the second scheme for luminescence color conversion in the embodiments of this application;

[0107] Figure 40 This is a schematic diagram of the process for configuring light conversion materials in the second scheme of light emission color conversion in the embodiments of this application;

[0108] Figure 41 This is a schematic diagram of the process for the third scheme of light emission color conversion in the embodiments of this application. Detailed Implementation

[0109] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0110] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0111] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0112] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, " / " means or, and "several" means one or more, unless otherwise explicitly specified.

[0113] In this embodiment, the LED chip is a nanoscale chip, which includes a chip body and two chip electrodes spaced apart on the chip body. The two chip electrodes can be located at any position along the length of the chip body. Optionally, the two chip electrodes are respectively wrapped around the two ends of the chip body, that is, the electrodes surround the outer wall of the chip body and are located at the two ends of the chip body.

[0114] In this embodiment, a plurality of electrode units are disposed on the substrate. Each electrode unit includes a plurality of substrate electrodes (which may be two or three electrodes). The plurality of electrode units are spaced apart, and the substrate electrodes of each electrode unit are also spaced apart. When the electrode unit includes two substrate electrodes (which can be classified as a first substrate electrode and a second substrate electrode), in a preferred embodiment, the distance between the two chip electrodes of the LED chip is greater than the minimum distance between two adjacent substrate electrodes. The distance between the two chip electrodes of the LED chip refers to the minimum distance between the two chip electrodes.

[0115] Please see Figure 1 , Figure 1 The image shown is of a type of LED chip (hereinafter referred to as Type A LED chip) 20 that can be used in this application. The chip body of this type of LED chip 20 is a columnar structure. Figure 1 The horizontal direction in the diagram represents the height (length) of the LED chip 20, and the vertical direction represents its width. Generally, its length should be greater than its width, and its shape can be a cylinder (i.e., a circular cross-section along the vertical direction), a cuboid, or other suitable shapes. For example... Figure 1As shown, along the length direction of the chip body, there are, in sequence, a first chip electrode 1, a first semiconductor conductive layer 2, an active region 3, a second-type semiconductor conductive layer 4, and a second chip electrode 5. One of the first semiconductor conductive layer 2 and the second-type semiconductor conductive layer 4 is an n-type semiconductor conductive layer, and the other is a p-type semiconductor conductive layer. One of the first chip electrode 1 and the second chip electrode 5 is a positive electrode, and the other is a negative electrode. When the first chip electrode 1 and the second chip electrode 5 are respectively connected to the positive (negative) electrode and the negative (positive) electrode of the power supply, and a suitable voltage is applied, the LED chip 20 is driven to emit light. The insulating layer 6 is coated on the side surface of the LED column, and its function is to prevent the LED chip 20 from short-circuiting with the outside, and can passivate the side wall of the active layer to improve the quantum efficiency. At this time, the minimum distance between the two chip electrodes 1 and 5 of the LED chip refers to the distance between the right side wall of the first chip electrode 1 and the left side wall of the second chip electrode 5.

[0116] Please refer to Figure 2 , Figure 1 shown is another type of LED chip (hereinafter referred to as B-type LED chip) 20 that can be used in this application. The components represented by the reference numerals 1 to 5 are the same as those of the A-type LED chip, except that the coating layer 7 is a special material, which, in addition to having the functions of insulation and passivation, also has the function of color conversion (such as a light conversion material). This special material is composed of a semiconductor with a specific bandgap and is prepared and formed in the LED chip manufacturing process.

[0117] Generally, the part between the two chip electrodes of the columnar LED chip 20 is completely coated by the insulating layer 6. The first semiconductor conductive layer 2, the active region 3, the second-type semiconductor conductive layer 4, and the insulating layer 6 constitute the chip body. The first chip electrode 1 and the second chip electrode 5 are spaced apart and wrapped around the periphery in the length direction of the chip body. Typically, the lengths of the first chip electrode 1 and the second chip electrode 5 in the width direction of the LED chip 20 are greater than or equal to the width of the chip body, so that when the LED chip 20 is placed horizontally on a plane, the first chip electrode 1 and the second chip electrode 5 can contact the plane. Optionally, the first chip electrode 1 and the second chip electrode 5 are respectively wrapped at both ends of the chip body.

[0118] In one embodiment, the chip body is a cylinder, and the two chip electrodes 1 and 5 are spaced apart on the side surface of the cylinder. Generally, the structures of the two chip electrodes 1 and 5 are the same, and the chip electrodes 1 and 5 are in a circular ring structure, with the outer surface being a circular ring and surrounding the side surface of the chip body. The difference between the outer diameter of the chip electrodes 1 and 5 and the radius of the chip body is greater than 0 and less than 3 mm. That is, the radius of the outer surface of the chip electrode is defined as R, and the radius of the chip body is defined as r, and 0 < R - r < 3 mm. It should be noted that 3 mm is only a preferred example, and there is no limitation here.

[0119] In one embodiment, the spacing between the two chip electrodes 1 and 5 refers to the minimum distance between the two chip electrodes 1 and 5 on the side surface of the chip body. When both chip electrodes 1 and 5 are arranged parallel to the bottom surface of the chip body, the spacing between the two chip electrodes 1 and 5 is the distance between their cross-sections, or the distance between their center points. In one embodiment, the two chip electrodes 1 and 5 are respectively disposed at both ends of the chip body, and each chip electrode 1 and 5 covers one bottom surface of the chip body and a portion of its side surface connected to the bottom surface.

[0120] In one embodiment, the spacing between the two chip electrodes 1 and 5 is equal to the difference between the distance between the two ends of the chip body and the width between the two chip electrodes 1 and 5 (the width refers to the dimension of the LED chip 20 in the length direction).

[0121] In one embodiment, when the chip body is a pillar, two chip electrodes 1 and 5 are spaced apart at the two ends of the pillar, and the distance between the chip electrodes 1 and 5 is equal to the distance between the two ends of the pillar.

[0122] In one embodiment, the chip body is a cylinder, and the two chip electrodes 1 and 5 respectively cover the ends of the cylinder. In other embodiments, the two chip electrodes 1 and 5 may also cover the middle portion of the cylinder other than the ends.

[0123] In one embodiment, the chip body is a prism, and two chip electrodes 1 and 5 are spaced apart on the side of the prism. Each chip electrode 1 or 5 includes multiple chip sub-electrodes (not shown in the figure), and the number of chip sub-electrodes is equal to the number of side edges of the prism. Each chip sub-electrode protrudes from one side of the chip body, and the chip electrodes 1 or 5 can form a corresponding ring array. It is understood that the width of any side of the prism should be less than the minimum distance between two adjacent substrate electrodes (the width of the side can be considered as the side length of the intersection between the cross-section of the prism and the side). For example, the prism can be a triangular prism, a quadrangular prism, a pentagonal prism, or a hexagonal prism; there is no limitation on this.

[0124] In a preferred embodiment, the prism can be one of a regular triangular prism, a regular square prism, a regular pentagonal prism, or a regular hexagonal prism.

[0125] In another preferred embodiment, the plurality of chip sub-electrodes have the same external shape and size. However, in other embodiments, the plurality of chip sub-electrodes may have the same or different external shapes and sizes. This is not limited here.

[0126] In one embodiment, the chip body is a prism, and the distance between the two chip electrodes 1 and 5 can refer to the distance between the cross-sections of the formed annular array. In one embodiment, the chip electrodes 1 and 5 of the annular array each cover one bottom surface (end surface) of the chip body.

[0127] The LED chip transfer method provided in this technical solution uses a solution method (or fluid self-assembly method) to transfer LED chips. The LED chips are uniformly placed in a solution, which flows freely on the substrate of the backplane, causing the LED chips to move randomly. After the solution evaporates, the columnar LED chips are randomly deposited horizontally on the substrate, allowing the two chip electrodes to contact the substrate electrodes, completing the transfer process. Therefore, the substrate electrodes should be designed to maximize the probability that the two chip electrodes of the LED chip will land on different substrate electrodes, given the random distribution of the LED chips.

[0128] In one embodiment, see Figures 3A-6B Below are four feasible electrode shape designs for the backplane. Several electrode units are spaced apart on the first surface of the substrate 10. Each electrode unit includes two types of substrate electrodes 11 and 12 with identical structures and spaced apart, or three types of substrate electrodes 11, 12, and 13 with identical structures and spaced apart. The spacing between each substrate electrode (i.e., the minimum distance) should be limited. The spacing between each substrate electrode refers to the distance between directly opposite edges. Figure 3A The distance between the right side of the white square in the first row and the left side of the diagonal square in the second row is the minimum distance between two adjacent chip electrodes. It should be noted that the structural consistency mentioned here can refer to the consistent shape of the substrate electrodes. For example, in one embodiment, substrate electrodes 11 and 12 are square; in another embodiment, the cross-sections of substrate electrodes 11, 12, and 13 are circular. More preferably, the dimensions of the substrate electrodes can also be consistent. For example, the cross-sections of substrate electrodes 11, 12, and 13 are all circular, and the radii of the circles corresponding to substrate electrodes 11, 12, and 13 are consistent. However, in practical applications, the dimensions of the substrate electrodes can differ, and this is not a limitation here.

[0129] Please see Figures 3A-5BIn one embodiment, the substrate electrodes may include two types: first substrate electrodes 11 and second substrate electrodes 12 spaced apart. The first substrate electrodes 11 and second substrate electrodes 12 have substantially the same shape and structure, and slight deviations are permissible without affecting performance. The first substrate electrodes 11 and second substrate electrodes 12 on the substrate 10 are arranged in a staggered pattern along the longitudinal direction and also in a staggered pattern along the transverse direction. That is, adjacent to a first substrate electrode 11 are all second substrate electrodes 12, and similarly, adjacent to a second substrate electrode 12 are all first substrate electrodes 11. For example, a second substrate electrode 12 may be disposed between two adjacent first substrate electrodes 11, and a first substrate electrode 11 may be disposed between two adjacent second substrate electrodes 12. Figure 3A , 3B As shown in 4A and 4B.

[0130] In one embodiment, the first substrate electrode 11 and the second substrate electrode 12 are arranged at intervals, and the minimum distance between any two first substrate electrodes 11 is greater than the minimum distance between any two first substrate electrodes 11 and the second substrate electrode 12.

[0131] Viewed on the first surface of the entire substrate 10, a plurality of substrate electrodes of one type surround a substrate electrode of another type, and the minimum distance between any two substrate electrodes of the same type is greater than the minimum distance between any two substrate electrodes of different types.

[0132] Please see Figures 5A-6B In one embodiment, the substrate electrodes include three types: a first substrate electrode 11, a second substrate electrode 12, and a third substrate electrode 13 with identical structures. Any one of the first substrate electrode 11, the second substrate electrode 12, and the third substrate electrode 13 on the substrate is adjacent to the other two substrate electrodes, such that the first substrate electrode 11 is adjacent to both the second substrate electrode 12 and the third substrate electrode 13, and also adjacent to the second substrate electrode 12 and the third substrate electrode 13 in adjacent electrode units. That is, everything adjacent to the first substrate electrode 11 is either the second substrate electrode 12 or the third substrate electrode 13; similarly, everything adjacent to the second substrate electrode 12 is either the first substrate electrode 11 or the third substrate electrode 13, and everything adjacent to the third substrate electrode 13 is either the first substrate electrode 11 or the second substrate electrode 12. Viewed from the first surface of the entire substrate 10, multiple substrate electrodes of two types surround one of another type of substrate electrode. For example, a second substrate electrode 12 and / or a third substrate electrode 13 may be disposed between any two adjacent first substrate electrodes 11, a first substrate electrode 11 and / or a third substrate electrode 13 may be disposed between any two adjacent second substrate electrodes 12, and a second substrate electrode 12 and / or a third substrate electrode 13 may be disposed between any two adjacent third substrate electrodes 13. Figure 5A , 5B As shown in 6A and 6B.

[0133] Electrodes of the same type on substrate 10 are short-circuited to each other via electrode lines on substrate 10. Electrodes of different types (such as the first substrate electrode 11 and the second substrate electrode 12) can be subjected to different voltages to form a potential difference. If the two chip electrodes of LED chip 20 are in contact with and electrically connected to substrate electrodes of different types, the two chip electrodes of the LED chip will be lit due to the potential difference. Otherwise, if the two chip electrodes of LED chip 20 fall on the same substrate electrode, the potential difference between its two ends will be 0, and it will not be lit. Therefore, this situation should be avoided as much as possible. Since the orientation of LED chip 20 is random, in order to effectively drive LED chip 20, appropriate driving circuits and driving signal timing should also be used, which will be described later. In addition, it should be noted that... Figures 3A-6B The described scenario involves a large number of repeated substrate electrodes. The actual number of repeated substrate electrodes should be designed with reference to the pixel area, ensuring that the area occupied by the entire substrate electrode matches the pixel area. It should be noted that different types of substrate electrodes can be substrate electrodes that are subjected to the same voltage at different times; that is, different types of substrate electrodes are not connected to the same voltage at the same time, or different types of substrate electrodes are connected to the same voltage at different times.

[0134] Please see Figure 3A and Figure 3B The disclosed design is a first substrate electrode structure with two types of substrate electrodes: a pattern-filled first substrate electrode 11 and an unfilled second substrate electrode 12. The cross-sectional shape of each substrate electrode 11 and 12 is square. The square substrate electrodes 11 and 12 are arranged in a matrix in space, with a gap between them. In one embodiment, the gap between the first substrate electrode 11 and the second substrate electrode 12 (such as the distance between two opposite sides of an adjacent first substrate electrode 11 and second substrate electrode 12) is consistent. Figure 3B The diagram shows the result of randomly placing LED chips 20. An unfilled LED chip 20 represents an example of transfer failure, while an LED chip 20 with a pattern fill represents an example of successful transfer.

[0135] Based on experiments, the ratio of the square side length to the LED chip length under this type of substrate electrode design, and the corresponding proportion of successfully transferred LED chips, are shown in Table 1 below:

[0136] Table 1:

[0137]

[0138] Therefore, when the ratio of the side length of the square to the spacing between the two electrode plates of the LED chip 20 is between 0.6 and 1.2, the proportion of successfully transferred LED chips exceeds 50%. Furthermore, with this type of substrate electrode design, a minimum spacing between adjacent substrate electrodes that is 0.01 to 0.1 times the side length of the square electrode can further improve the proportion of successfully transferred LED chips. It should be noted that if the spacing between the two electrode plates of the LED chip 20 is less than the sum of the side length of the square and the minimum distance between the first substrate electrode 11 and the second substrate electrode 12, it can prevent one LED chip 20 from short-circuiting two adjacent identical substrate electrodes 11 / 12. To maximize the transfer success rate, setting the LED chip length to be approximately equal to the side length of the square results in an even better transfer success rate, achieving 64%.

[0139] Please see Figure 4A and Figure 4B The disclosed design is a second type of substrate electrode structure, which includes two types of substrate electrodes: a pattern-filled first substrate electrode 11 and an unfilled second substrate electrode 12. The cross-sectional shape of each substrate electrode 11 and 12 is an equilateral triangle. The spacing between adjacent first substrate electrodes 11 and second substrate electrodes 12 is consistent. Similarly, the triangular substrate electrodes 11 and 12 are spatially close-packed, with a gap left between the substrate electrodes 11 and 12. Figure 4B The diagram illustrates the transfer process after LED chip transfer. Blank-filled LED chips 20 represent examples of failed transfers, while pattern-filled LED chips 20 represent successful transfers. Success means that the two chip electrodes of the LED chip 20 are respectively connected to two different types of substrate electrodes on the substrate; otherwise, it is considered a failed transfer.

[0140] Based on experiments, the ratio of the equilateral triangle side length to the LED chip length under this substrate electrode design, and the corresponding proportion of successfully transferred LED chips, are shown in Table 2 below:

[0141] Table 2:

[0142]

[0143] like Figure 4A and 4BAs shown, in the same row of electrodes, the bottom edges of the same type of substrate electrodes (using the side of the equilateral triangle parallel to the horizontal direction as the bottom edge) are located on the same straight line, such as the bottom edges of the first substrate electrode 11 in the same row being on the same horizontal line, and the bottom edges of the second substrate electrode 12 in the same row being on the same horizontal line. Preferably, one side of the equilateral triangle corresponding to the first substrate electrode 11 in the electrode unit is opposite and parallel to one side of the equilateral triangle corresponding to the second substrate electrode 12. Preferably, the two sides of the first substrate electrode 11 and the second substrate electrode 12 of adjacent equilateral triangles that are close to each other should be directly opposite each other. If the ratio of the side length of the equilateral triangle to the distance between the two chip electrodes of the LED chip 20 is in the range of 0.4 to 0.7, the proportion of successfully transferred LED chips exceeds 50%. In addition, under this type of substrate electrode design, the ratio of the minimum distance between adjacent first substrate electrodes 11 and second substrate electrodes 12 (the distance between the two opposite parallel sides of two adjacent equilateral triangles) to the side length of the equilateral triangle is in the range of 0.005 to 0.05, which can further improve the proportion of successfully transferred LED chips 20. To maximize the transfer success rate, setting the side length of the triangle to about 0.55 times the distance between the two chip electrodes of the LED chip 20 results in a better transfer success rate. About 61% of the LED chips 20 are successfully transferred to the backplane. It should be noted that success means that the two chip electrodes of the LED chip 20 are connected to different types of substrate electrodes.

[0144] Please see Figure 5A and Figure 5B The disclosed design is a third type of substrate electrode structure, comprising three types of substrate electrodes: a first substrate electrode 11 with two different pattern fillings, a second substrate electrode 12, and a third substrate electrode 13 without filling. Each substrate electrode 11, 12, and 13 has a regular hexagonal cross-sectional shape. The hexagonal electrodes 11, 12, and 13 are spatially close-packed, with spacing between them. The spacing between adjacent substrate electrodes 11, 12, and 13 is equal; this spacing refers to the minimum distance between two adjacent substrate electrodes. Figure 5A The distance between the two opposite and parallel sides of the adjacent first substrate electrode 11 and second substrate electrode 12 is the minimum distance between adjacent substrate electrodes. Figure 5B The diagram illustrates the results after randomly placing LED chips 20. Blank-filled LED chips 20 represent examples of failed transfers, while pattern-filled LED chips 20 represent successful transfers. Based on experiments, the ratio of the inscribed circle diameter of the regular hexagon to the length of the LED chip, corresponding to the proportion of successfully transferred LED chips 20 under this substrate electrode design, is shown in Table 3 below:

[0145] Table 3:

[0146]

[0147] Therefore, in any electrode unit, one side of the regular hexagon corresponding to the first substrate electrode 11 is opposite and parallel to one side of the regular hexagon corresponding to the second substrate electrode 12, and the other side of the regular hexagon corresponding to the first substrate electrode 11 is opposite and parallel to one side of the regular hexagon corresponding to the third substrate electrode 13, preferably facing each other and parallel to each other. When the ratio of the inscribed circle diameter of the regular hexagon to the spacing between the two chip electrodes of the LED chip 20 is in the range of 0.2 to 1.8, the proportion of successfully transferred LED chips exceeds 60%. In addition, under this type of substrate electrode design, when the ratio of the minimum spacing between adjacent substrate electrodes to the side length of the regular hexagon electrode is in the range of 0.05 to 0.2, the proportion of successfully transferred LED chips 20 can be further improved. In order to maximize the transfer success rate, the optimal value of the spacing between the two chip electrodes of the LED chip 20 is 1.732 times the side length of the regular hexagon, or when the spacing between the two chip electrodes of the LED chip 20 is basically equal to the inscribed circle diameter of the regular hexagon, there is a better transfer success rate, at which point 98% of the chips can be successfully transferred.

[0148] Please see Figure 6A and Figure 6B The disclosed design is a fourth type of substrate electrode, which includes three types of substrate electrodes: a first substrate electrode 11 with two different pattern fillings, a second substrate electrode 12, and a third substrate electrode 13 without filling. The cross-sectional shape of each substrate electrode 11, 12, and 13 is circular. The circular electrodes 11, 12, and 13 are spatially close together, with a gap between them. The gap between adjacent substrate electrodes is equal. This gap refers to the difference between the distance between the centers of the circles corresponding to two adjacent substrate electrodes and the radii of the two circles (e.g., the difference between the distance between the centers of the circles of adjacent first substrate electrode 11 and second substrate electrode 12, minus the radii of the two circles, is the gap), which is the minimum distance between two adjacent substrate electrodes. Figure 6B The diagram illustrates the results after randomly placing LED chips 20. Blank-filled LED chips 20 represent examples of failed transfers, while pattern-filled LED chips 20 represent successful transfers. Based on experiments, the ratio of the circular diameter to the LED chip length under this substrate electrode design, and the corresponding proportion of successfully transferred LED chips 20, are shown in Table 4 below:

[0149] Table 4:

[0150]

[0151] Therefore, when the ratio of the diameter of the circle to the spacing between the two electrode plates of the LED chip 20 is between 0.6 and 1.8, the proportion of successfully transferred LED chips exceeds 50%. Furthermore, with this type of substrate electrode design, a ratio of the minimum spacing between adjacent substrate electrodes to the diameter of the circle electrode between 0.01 and 0.1 can further improve the proportion of successfully transferred LED chips. To maximize the transfer success rate, setting the spacing between the two electrode plates of the LED chip 20 to be approximately equal to the diameter of the circle electrode results in an even better transfer success rate, where 75% of the chips can be successfully transferred.

[0152] Based on any of the above-mentioned electrode patterns, after the LED chip 20 is transferred onto the substrate 10 and makes electrical contact with the substrate electrodes on the substrate 10, it forms the pixel structure in the back panel of the LED display device.

[0153] Please see Figure 7 In some embodiments, the pixel structure includes a substrate 10, a plurality of electrode units, and a plurality of LED chips 20. The electrode units are spaced apart on a first surface of the substrate 10. The distance between two chip electrodes of the LED chip 20 is greater than the minimum distance between any two adjacent first substrate electrodes 11 and second substrate electrodes 12. In this embodiment, the two chip electrodes of an LED chip 20 are respectively connected to the first substrate electrode 11 and the second substrate electrode 12 of an electrode unit, or one chip electrode of an LED chip 20 is connected to the first substrate electrode 11 of an electrode unit, and the other chip electrode of the LED chip 20 is connected to the second substrate electrode 12 of another electrode unit adjacent to the first substrate electrode 11.

[0154] Generally, the minimum spacing between adjacent electrode units is approximately equal to the minimum distance between the first substrate electrode 11 and the second substrate electrode 12 between the electrode units, and slight deviations are permissible without affecting performance. This results in a compact and neat arrangement of substrate electrodes throughout the pixel structure, which is beneficial for improving the transfer efficiency of the LED chip.

[0155] The pixel structure described above, with two types of substrate electrodes 11 and 12 spaced apart on the substrate 10, facilitates the uniform and efficient transfer of the LED chip 20, resulting in uniform light emission in the manufactured lamp board and display device. Furthermore, since the two types of substrate electrodes 11 and 12 do not need to be distinguished as positive or negative, after the LED chip 20 is randomly connected to the two types of substrate electrodes 11 and 12, only an appropriate timing of the driving power supply needs to be set on the two types of substrate electrodes 11 and 12 to create a potential difference between them. This allows all the LED chips 20 randomly connected to the two types of substrate electrodes 11 and 12 to be lit, increasing the transfer success rate. Simultaneously, the LED chip 20 is lit in a timed manner, thus improving its lifespan and reducing losses.

[0156] Please see Figure 8 In another embodiment, the electrode unit further includes at least one third substrate electrode 13. The first substrate electrode 11, the second substrate electrode 12, and the third substrate electrode 13 are arranged at intervals, and the third substrate electrode 13 has a structure that is substantially the same as that of the first substrate electrode 11, allowing for slight deviations without affecting performance. Thus, when the electrode unit has three types of substrate electrodes, the two chip electrodes of the LED chip 20 are respectively connected to any two of the first substrate electrode 11, the second substrate electrode 12, and the third substrate electrode 13.

[0157] Generally, the minimum distances between the first substrate electrode 11, the second substrate electrode 12, and the third substrate electrode 13 in the electrode unit are basically the same, and slight deviations are allowed without affecting performance. The minimum spacing between adjacent electrode units is equal to the minimum distance between the first substrate electrode 11 and the second substrate electrode 12 between the electrode units, and slight deviations are allowed without affecting performance. This makes the substrate electrodes on the entire pixel structure compact and neat, which is beneficial to improving the utilization rate of the substrate 10 and increasing the transfer success rate of the LED chip.

[0158] The pixel structure described above, with three types of substrate electrodes 11, 12, and 13 spaced apart on the substrate 10, facilitates the more uniform and effective transfer of the LED chip 20, resulting in a lamp panel and display device with uniform light emission. Furthermore, the three types of substrate electrodes 11, 12, and 13 do not need to be distinguished as positive or negative. After the LED chip 20 is randomly connected to any two types of substrate electrodes (11, 12) / (12, 13) / (13, 11), it is only necessary to apply the electrodes to the two types of substrate electrodes (11, 12) / (12, 13) to ensure uniform light emission. By setting an appropriate timing drive power supply on (13) / (13, 11), a potential difference can be created on the electrodes (11, 12) / (12, 13) / (13, 11) of the two substrates. The LED chips 20 randomly connected on the electrodes (11, 12) / (12, 13) / (13, 11) of the two substrates can be lit, further improving the transfer success rate. At the same time, the LED chips 20 are lit in three groups according to the timing, which can further improve their lifespan and reduce losses.

[0159] Please see Figure 7 The substrate 10 may be made of materials such as glass, crystal, sapphire substrate, plastic, or flexible polymer film, but this disclosure is not limited thereto. The area of ​​the substrate 10 according to the embodiment may vary depending on the area of ​​the substrate electrodes disposed on the first surface of the substrate 10 and the size and number of the LED chips 20 disposed between the respective substrate electrodes, as will be described later.

[0160] A driving circuit 30 for driving the LED chip 20 can be fabricated on the substrate 10. In a pixel structure with two types of substrate electrodes, the driving circuit 30 is electrically connected to the first substrate electrode 11 and the second substrate electrode 12; see also Figure 8 In a pixel structure with three types of substrate electrodes, the driving circuit 30 is electrically connected to the first substrate electrode 11, the second substrate electrode 12 and the third substrate electrode 13.

[0161] Generally, the driving circuit 30 includes a series of components, such as thin film transistors (TFTs), capacitors, etc. The driving circuit 30 also includes metal interconnects between components. There is an intermediate insulating layer 102 on top of the driving circuit 30, and specific positions are connected to the electrode units above through metal vias 50.

[0162] In one embodiment, see Figure 7 and Figure 8 An insulating layer 101 is applied between adjacent substrate electrodes 11 and 12, making the upper surface of the entire substrate 10 planar with no height difference, which helps improve the transfer success rate of the LED chip 20. It is understood that a planar upper surface of the substrate 10 ensures that the cylindrical LED chip 20, and LED chips 20 whose side width (when the chip body is a prism) is less than the minimum distance between two adjacent substrate electrodes (11, 12) / (12, 13) / (13, 11), will not short-circuit when their chip electrodes fall into the gap between the two adjacent substrate electrodes (11, 12) / (12, 13) / (13, 11).

[0163] In one embodiment, when the LED chip 20 is placed on the substrate 10, it is positioned horizontally on the uppermost surface of the pixel structure. Figure 7 The diagram shows a cross-sectional view of the pixel structure after the LED chip 20 is placed. Since the upper surface of the substrate 10 is flat, the position of the LED chip 20 is relatively regular and there is no situation such as the LED chip 20 being lifted up, which is relatively neat.

[0164] Please see Figure 9 In one embodiment, applicable to a pixel structure having two types of substrate electrodes, the driving circuit 30 includes: a first driving transistor M1-1, a second driving transistor M1-2, a third driving transistor M2-1, a fourth driving transistor M2-2, a first capacitor C1, a second capacitor C2, power lines P1 and P2 for connecting to a power source, a data line Data for connecting to a data signal, and a scan line Scan for connecting to a scan signal.

[0165] In this embodiment, the first electrode of the first driving transistor M1-1 is electrically connected to the first power supply line P1, and the second electrode of the first driving transistor M1-1 is electrically connected to at least one first substrate electrode 11; the first electrode of the second driving transistor M1-2 is electrically connected to the second power supply line P2, and the second electrode of the second driving transistor M1-2 is electrically connected to at least one second substrate electrode 12; the first electrode of the third driving transistor M2-1 is electrically connected to the control electrode of the first driving transistor M1-1, and the second electrode of the third driving transistor M2-1 is electrically connected to the data line Data, and the control electrode of the third driving transistor M2-1 is electrically connected to the scan line Scan; the first electrode of the fourth driving transistor M2-2 is electrically connected to the control electrode of the second driving transistor M1-2, and the second electrode of the fourth driving transistor M2-2 is electrically connected to the data line Data, and the control electrode of the fourth driving transistor M2-2 is electrically connected to the scan line Scan.

[0166] Please see Figure 10 In another embodiment, applicable to a pixel structure with three types of substrate electrodes, the driving circuit 30 includes a first driving transistor M1-1, a second driving transistor M1-2, a third driving transistor M1-3, a fourth driving transistor M2-1, a fifth driving transistor M2-2, a sixth driving transistor M2-3, a first capacitor C1, a second capacitor C2, a third capacitor C3, power lines P1, P2, and P3 for connecting to a power source, a data line Data for connecting to a data signal, and a scan line Scan for connecting to a scan signal.

[0167] The first electrode of the first driving transistor M1-1 is electrically connected to the first power supply line P1, and the second electrode of the first driving transistor M1-1 is electrically connected to at least one first substrate electrode 11; the first electrode of the second driving transistor M1-2 is electrically connected to the second power supply line P2, and the second electrode of the second driving transistor M1-2 is electrically connected to at least one second substrate electrode 12; the first electrode of the third driving transistor M1-3 is electrically connected to the third power supply line P3, and the second electrode of the third driving transistor M1-3 is electrically connected to at least one third substrate electrode 13; the first electrode of the fourth driving transistor M2-1 is electrically connected to the control electrode of the first driving transistor M1-1, and the second electrode of the fourth driving transistor M2-1 is electrically connected to the data line Data, and the control electrode of the fourth driving transistor M2-1 is electrically connected to the scan line Scan; The first electrode of the fifth driving transistor M2-2 is electrically connected to the control electrode of the second driving transistor M1-2; the second electrode of the fifth driving transistor M2-2 is electrically connected to the data line Data; and the control electrode of the fifth driving transistor M2-2 is electrically connected to the scan line Scan. The first electrode of the sixth driving transistor M2-3 is electrically connected to the control electrode of the third driving transistor M1-3; the second electrode of the sixth driving transistor M2-3 is electrically connected to the data line Data; and the control electrode of the sixth driving transistor M2-3 is electrically connected to the scan line Scan. The first capacitor C1, the second capacitor C2, and the third capacitor C3 are respectively connected between the control electrode and the first electrode of the first driving transistor M1-1, between the control electrode and the first electrode of the second driving transistor M1-2, and between the control electrode and the first electrode of the third driving transistor M1-3.

[0168] In the embodiments of the two driving circuits 30 described above, the first capacitor C1, the second capacitor C2, and the third capacitor C3 are used for charging and discharging to drive the connected driving transistor to switch on and off; the first electrode, the second electrode, and the control electrode of the transistor are the source, drain, and gate of the transistor, respectively. The transistor is generally a TFT device, such as an n-type MOSFET, a p-type MOSFET, or an insulated-gate bipolar transistor.

[0169] Please see Figures 3A-4B , Figure 11 as well as Figure 13BIn some embodiments, the pixel structure having two types of substrate electrodes includes a plurality of first substrate electrodes 11, a plurality of second substrate electrodes 12, a first substrate electrode line 41, and a second substrate electrode line 42. The first substrate electrode line 41 connects the plurality of first substrate electrodes 11 to each other through a metal via 50; the second substrate electrode line 42 connects the plurality of second substrate electrodes 12 to each other through a metal via 50. The metal via 50 penetrates the intermediate insulating layer 102. Since a plurality of one type of substrate electrode surrounds a single one of the other type of substrate electrode among the plurality of first substrate electrodes 11 and the plurality of second substrate electrodes 12, the LED chip 20, when randomly distributed, has the highest probability that its two chip electrodes are in electrical contact with different first substrate electrodes 11 and second substrate electrodes 12 respectively.

[0170] Please see Figures 5A-6B , Figure 12 as well as Figure 14B In some embodiments, the pixel structure with three types of substrate electrodes includes multiple first substrate electrodes 11, multiple second substrate electrodes 12, multiple third substrate electrodes 13, first substrate electrode lines 41, second substrate electrode lines 42, and third substrate electrode lines 43. The first substrate electrode lines 41 connect the multiple first substrate electrodes 11 to each other through metal vias 50; the second substrate electrode lines 42 connect the multiple second substrate electrodes 12 to each other through metal vias 50; and the third substrate electrode lines 43 connect the multiple third substrate electrodes 13 to each other through metal vias 50. The metal vias 50 penetrate the intermediate insulating layer 102. Since multiple first substrate electrodes 11, multiple second substrate electrodes 12, and multiple third substrate electrodes 13 surround one of two types of substrate electrodes, the LED chip 20, when randomly distributed, has the highest probability that two chip electrodes of the LED chip 20 make electrical contact with different first substrate electrodes 11, second substrate electrodes 12, and third substrate electrodes 13.

[0171] Please see Figure 12The upper surface of the substrate 10 can be considered to have three layers: the upper layer is the electrode layer of the electrode region (electrode unit), and the first substrate electrode 11, the second substrate electrode 12, and the third substrate electrode 13 are electrically isolated by an upper insulating layer 101; the lower layer is the electrode line layer where gold fingers, first substrate electrode lines 41, second substrate electrode lines 42, and third substrate electrode lines 43 are disposed, and the gold fingers, first substrate electrode lines 41, second substrate electrode lines 42, and third substrate electrode lines 43 are electrically isolated by a lower insulating layer (i.e., the second insulating layer) 103; the middle layer is the via layer where metal vias 50 are disposed to electrically connect the electrode units and electrode lines respectively, and each metal via 50 is electrically isolated by an intermediate insulating layer (first insulating layer) 102. The chip electrodes of the LED chip 20 are connected to the driving circuit 30 in a one-to-one correspondence through the substrate electrodes 11, 12, 13, metal vias 50, and electrode lines 41, 42, 42.

[0172] The following example illustrates the upper and lower layers of a pixel structure; for instance, in a pixel structure with two types of square electrodes, Figure 13A The surface of the upper layer (electrode layer) of the structure is shown. Figure 13B The bottom surface of the lower layer (electrode line layer) of the structure is shown, with black circles indicating metal vias 50. Figure 13A , 13B In the diagram, the figures shown are vertically corresponding in the solid structure. Figure 13A In the figure, each substrate electrode 11, 12 is connected to at least one metal via 50; Figure 13B In the circuit, the first substrate electrode 11 and the second substrate electrode 12 are connected together by the first substrate electrode line 41 and the second substrate electrode line 42 through the metal via 50 to form a short circuit and are led out to the drive circuit 30.

[0173] For example, in a pixel structure with three types of regular hexagonal electrodes, Figure 14A The surface of the upper layer (electrode layer) of the structure is shown. Figure 14B The bottom surface of the lower layer (electrode line layer) of the structure is shown, with black circles indicating metal vias 50. Figure 14A , 14B In the diagram, the figures shown are vertically corresponding in the solid structure. Figure 14A In the figure, each substrate electrode 11, 12, and 13 is connected to at least one metal via 50. Figure 14B In the circuit, the first substrate electrode 11, the second substrate electrode 12 and the third substrate electrode 13 are connected together by the first substrate electrode line 41, the second substrate electrode line 42 and the third substrate electrode line 43 through the metal via 50 to form a short circuit and lead out to the drive circuit 30.

[0174] in addition, Figures 13A-14BIn the diagrams, since the areas shown represent the locations where various substrate electrodes are positioned, and the transfer of the LED chip 20 primarily occurs within these areas, these areas can be defined as electrode regions. Generally, one electrode region corresponds to one electrode unit in the description of relevant embodiments.

[0175] In one embodiment, in the actual pixel structure, the area where the driving circuit 30 is located (or the TFT area) and the electrode unit can be arranged separately and side by side. For example... Figure 15 The diagram shows a pixel structure for an RGB (red, green, blue) pixel, which contains three electrode units 1, 2, and 3 that emit different colors (RGB). In this pixel structure, the driving circuit 30 can be a single-layer design, either metal or a semiconductor device. Therefore, in the region of a pixel on the upper surface of the substrate 10, the three electrode units 1, 2, and 3 and the three driving circuits 30 are located in three corresponding electrode regions 1, 2, and 3, respectively. The region where the driving circuit 30 is located can be placed in the part not occupied by the electrode units 1, 2, and 3, so that the driving circuit 30 is located on one side of the electrode units 1, 2, and 3.

[0176] In another embodiment, the area where the driving circuit 30 is located and the electrode units can also be stacked. For example... Figure 11 , 12 As shown, the driving circuit 30 is located in the electrode layer ( Figure 16 Below electrode units 1, 2, and 3, the electrode line layer is located above and between the electrode layers, contacting the drive circuit 30. A top view of this stacked structure is shown below. Figure 16 As shown, this represents the area containing a single pixel. The three electrode regions 1, 2, and 3 each contain three electrode units 1, 2, and 3 that emit different colors (RGB). Since the projections of the driving circuit region (layer) and the electrode region (layer) onto the substrate 10 can overlap, this pixel structure allows for a larger light-emitting area to be placed per unit area, achieving a higher pixel density. Figure 15 Compared to the separate design shown, the stacked structure can save space, achieve higher device density, and transfer more chips in the same area of ​​the display device backplane.

[0177] In addition, stacked pixel structures, such as Figure 11 , 12As shown, the driving circuit 30 needs to be electrically connected to the first substrate electrode 11, the second substrate electrode 12, and the third substrate electrode 13. Therefore, special upper insulating layer 101, middle insulating layer 102, and lower insulating layer 103 need to be fabricated between them. The growth rate of the upper insulating layer 101, middle insulating layer 102, and lower insulating layer 103 can be 50% of that of conventional insulating layers, and the growth temperature is 30°C higher than that of conventional insulating layers. Furthermore, the total thickness of the upper insulating layer 101, middle insulating layer 102, and lower insulating layer 103 is not less than 100 nm, and preferably not more than 2000 nm. This is because if the thickness of the upper insulating layer 101, middle insulating layer 102, and lower insulating layer 103 is too thin, the insulation effect will be poor, and leakage will be easy. If the thickness of the upper insulating layer 101, middle insulating layer 102, and lower insulating layer 103 is too thick, it will make the deposition and fabrication of the metal via 50 difficult. In the stacked pixel structure, the driving circuit 30 layers have several TFT device structures. Their heights differ from those of the non-TFT device parts. The thicknesses of the upper insulating layer 101, the middle insulating layer 102, and the lower insulating layer 103 should compensate for the height difference between them so that the upper electrode metal is on the same plane.

[0178] In some embodiments, the width of the spacing between two adjacent substrate electrodes (11, 12) / (12, 13) / (13, 11) is 0.005 to 0.2 times the side length (e.g., square, equilateral triangle) or diameter (e.g., the inscribed circle of a regular hexagonal electrode, a circle). Furthermore, the shape and related dimensions of each substrate electrode in the pixel structure are described in the above embodiments and will not be repeated here.

[0179] Please see Figure 9 In some embodiments, this application also provides a pixel structure driving method, including:

[0180] Step 1: Input scan signal and data signal to the electrode unit for addressing.

[0181] Step 2: Provide a current source to several electrode units, wherein a positive current is provided to one of the first substrate electrode 11 and the second substrate electrode 12 in sequence, and a negative current is provided to the other, so as to sequentially light up the LED chip 20 connected between the first substrate electrode 11 and the second substrate electrode 12.

[0182] It is understood that in this embodiment, a pixel structure with two types of substrate electrodes is used. The scan line Scan and the data line Data are used to input scan signals and data signals, respectively. The first power line P1 and the second power line P2 are connected to two current sources, respectively. Transistors M1-1 / 2 and M2-1 / 2 and capacitor C1 / 2 constitute three 2T (transistor) 1C (capacitor) driving circuits 30. LED chips 20 are randomly arranged between the first substrate electrode 11 and the second substrate electrode 12, and LED chips 20 with different polarities exist between different substrate electrodes.

[0183] Assume that the LED chip 20 between the first substrate electrode 11 and the second substrate electrode 12 includes D1 and D2. (See also...) Figure 17 This is a timing diagram of the current for the first power line P1 and the second power line P2. In this example, each cycle is divided into three stages. The first stage is addressing, during which there is no current in the first power line P1 and the second power line P2, allowing the scan line (Scan) and data line (Data) to perform the addressing action. In the latter two stages, the first power line P1 and the second power line P2 alternately act as current output terminals, while the other acts as a current inflow terminal. By setting the current output terminal to a constant current output, the total current of the LED chip 20 is also determined, and the total current will be evenly distributed among the parallel LED chips 20. Since current is proportional to brightness, when the total current is controlled, the total brightness is also controlled, and the displayed grayscale can also be controlled.

[0184] For example, in the second stage, the first power line P1 is the current outflow end and the second power line P2 is the current inflow end. At this time, the LED chip D1 with its positive terminal connected to the first power line P1 has current flowing through it, and the magnitude of the total current controls the total brightness of the LED chip D1.

[0185] Please see Figure 10 In other embodiments, a pixel structure driving method is also provided, including:

[0186] Step 1: Input scan signal and data signal to the electrode unit for addressing.

[0187] Step two, providing a current source to the plurality of electrode units, wherein a positive current is sequentially provided to one of the first substrate electrode 11, the second substrate electrode 12, and the third substrate electrode 13, and a negative current is provided to the other two, so as to sequentially light up the LED chip 20 connected between the first substrate electrode 11 and the second substrate electrode 12, the LED chip 20 between the first substrate electrode 11 and the third substrate electrode 13, and the LED chip 20 between the second substrate electrode 12 and the third substrate electrode 13.

[0188] It is understood that in this embodiment, a pixel structure with three types of substrate electrodes is applied, with the scan line Scan and data line Data respectively inputting scan signals and data signals. The first power line P1, the second power line P2, and the third power line P3 are respectively connected to three current sources. Transistors M1-1 / 2 / 3, M2-1 / 2 / 3, and capacitors C1 / 2 / 3 constitute three 2T1C driving circuits 30. LED chips 20 are randomly arranged between the first substrate electrode 11, the second substrate electrode 12, and the third substrate electrode 13, with each LED chip 20's two chip electrodes connected to different types of substrate electrodes.

[0189] Please see Figure 10 Assume that the LED chip 20 between the first substrate electrode 11, the second substrate electrode 12, and the third substrate electrode 13 includes electrodes D1, D2, D3, D4, D5, and D6. (See also...) Figure 18 This is a timing diagram of the current for the first power line P1, the second power line P2, and the third power line P3. In this example, each cycle is divided into four stages. The first stage is addressing, during which there is no current in the first power line P1, the second power line P2, and the third power line P3, so that the scan line Scan and the data line Data can perform the addressing action. In the following three stages, the first power line P1, the second power line P2, and the third power line P3 take turns acting as current output terminals, while the other two act as current inflow terminals. By setting the current output terminals to constant current output, the total current of the LED chip 20 is also determined, and the total current will be evenly distributed among the parallel LED chips 20. Since current is proportional to brightness, when the total current is controlled, the total brightness is also controlled, and the displayed grayscale can also be controlled.

[0190] For example, in the second stage, the first power line P1 is the current outflow end, and the second power line P2 and the third power line P3 are the current inflow ends. At this time, the LED chips D1 and D3 with their positive terminals connected to the first power line P1 have current flowing through them, and the magnitude of the total current controls the total brightness of the LED chips D1 and D3.

[0191] It should be noted that the high (level) voltage on the data line (Data) should be higher than the peak voltage of the power lines (P1, P2, P3), and the high (level) voltage on the scan line (Scan) should be higher than the high (level) voltage on the data line (Data) to ensure that the circuit works properly.

[0192] The aforementioned pixel structure driving method includes two or three types of substrate electrodes, without fixed positive and negative polarities. This allows the LED chip 20 to be randomly connected to two types of substrate electrodes. By sequentially providing positive current to the two or three substrate electrodes, a potential difference can be created between the two substrate electrodes, enabling the LED chip 20 randomly connected to both substrate electrodes to be lit. This significantly improves the effective utilization rate of the LED chip 20 transferred to the substrate 10, i.e., increases the success rate of transfer. At the same time, the LED chip 20 is lit in a time-sequential manner, which can improve its lifespan and reduce losses.

[0193] This application also provides a light panel and a display device, the light panel including the above-described pixel structure; the display device including the light panel.

[0194] In addition, this application also provides a method for transferring LED chips. It should be noted that the embodiments of the LED chip transfer method are illustrated using an electrode unit that includes three types of substrate electrodes as an example. The implementation method with an electrode unit including two types of substrate electrodes is actually similar to the implementation method with three types of substrate electrodes, and therefore will not be described again.

[0195] Please see Figure 19 and combined Figures 1 to 18 Example 1: The method for transferring LED chip 20 includes:

[0196] Step S110: Place a solution containing LED chips into a substrate. The substrate is provided with a plurality of electrode units, each electrode unit including a plurality of substrate electrodes. The LED chip includes a chip body and two chip electrodes spaced apart on the chip body. The distance between the two chip electrodes of the LED chip is greater than the minimum distance between any two adjacent substrate electrodes.

[0197] Step S130: Heat to evaporate the solution, so that the LED chip is placed on the substrate.

[0198] This method for transferring LED chip 20 is applicable to transferring LED chip 20 to the substrate 10 having two types of substrate electrodes. Please refer to [link to relevant documentation]. Figures 3A-4B This also applies to the transfer to substrate 10 of the above three types of substrate electrodes; please refer to [link / reference]. Figures 5A-6B .

[0199] The solution can be one or more of deionized water, toluene, xylene, methanol, ethanol, isopropanol, etc. Understandably, by placing the solution containing LED chips 20 onto a substrate 10 with spaced-apart substrate electrodes, the solution flows freely on the substrate 10, causing the LED chips 20 to move randomly. After the solution evaporates, the LED chips 20 precipitate on the substrate 10. Since the structure and spacing of the substrate electrodes on the substrate 10 are consistent, the LED chips can be distributed almost uniformly, and there is a maximum probability that the two chip electrodes of the LED chip 20 will fall onto different substrate electrodes and make electrical contact, completing the transfer process. The entire manufacturing process is simple and low-cost.

[0200] Please see Figure 20 In some embodiments, limiting groove pairs 60 may be formed in adjacent substrate electrodes, between the first substrate electrode 11 and the second substrate electrode 12, between the second substrate electrode 12 and the third substrate electrode 13, and between the third substrate electrode 13 and the first substrate electrode 11, extending from the center of one substrate electrode to the center of the other substrate electrode. Specifically, the limiting groove pairs 60 are formed in pairs on two adjacent substrate electrodes, and after the limiting groove pairs 60 are connected, they extend from the surface of one substrate electrode to the surface of the other substrate electrode. It is understood that the center of the substrate electrode refers to a location other than the edge of the substrate electrode (e.g., Figure 20 The upper surface of the first substrate electrode 11 shown is defined by a base edge and the area enclosed by two side edges connected to the base edge (the upper surface refers to the side of the first substrate electrode 11 that contacts the LED chip 20). The limiting grooves 60 penetrate the filling layer between the substrate electrodes, i.e., the upper insulating layer 101. Because these limiting grooves 60 constitute potential low points, the LED chip 20 has a greater probability of falling into these limiting grooves 60, increasing the success rate of the LED chip 20 transfer process under the traction of the limiting grooves 60.

[0201] Please see Figure 21A , 21BThe two examples correspond to the cases of electrodes with square cross-sections and electrodes with regular hexagonal cross-sections, respectively. It is understood that the limiting groove pair 60 is formed by connecting slots respectively formed on two adjacent substrate electrodes; the directions of each pair of slots should be aligned; in each pair of slots, the length ratio of the two slots is between 0.5 and 2 (e.g., if the slot pair includes a first slot and a corresponding second slot, the length ratio of the first slot to the second slot can be 0.5 to 2); and the width of each slot is adapted to, for example, the width of the LED chip 20; the sum of the length of the limiting groove pair 60 and the distance between the corresponding two adjacent substrate electrodes should be 1.05 to 1.3 times the length of the LED chip 20. Furthermore, the distance between the position of each slot and the edge of the adjacent substrate electrode is not less than twice the width of the LED chip 20.

[0202] In another embodiment, slots can be formed in two adjacent substrate electrodes, with the two slots having the same direction and their openings facing each other. These two slots form a limiting slot, and the structure of the limiting slot can be the same as the structure of the slot pair described above, which will not be repeated here.

[0203] Please see Figure 22 In some embodiments, the transfer method, before or simultaneously with step S110, further includes step S120: a process of agitating the solution to connect at least one LED chip 20 to two substrate electrodes in an electrode unit. It is understood that agitating the solution can make the LED chips 20 more uniformly distributed on the surface of the substrate 10; furthermore, the LED chips 20 may also have a greater probability of falling within these limiting groove pairs 60. In step S120, the agitation duration, for example, is 10 s to 600 s.

[0204] Specifically, the methods of agitating the solution include: shaking the solution, applying a magnetic field to the solution (using magnetic force to move the LED chip 20), applying a shock wave (such as a sound wave) to the solution, and stirring the solution, or one or more of these methods.

[0205] Please see Figure 23 In some embodiments, the substrate 10 has several regions, each corresponding to an electrode unit. Step S110, which involves placing a solution containing several LED chips into the substrate, includes placing the solution into each region separately. Of course, each region can correspond to two or three electrode units, allowing for the direct placement of the solution into the region of an RGB pixel.

[0206] In this way, the solution can be selectively placed onto the substrate 10, for example, the solution can be printed onto the area of ​​the substrate 10 where there are substrate electrodes. Since other areas do not require LED chips 20, this selective placement of the solution can save the number of LED chips 20. If this method is adopted, some structures that restrict the flow of the solution can be set near the electrode area on the substrate 10, such as a raised edge along the periphery of each electrode area to restrict the flow of the solution, so that the solution is less likely to flow to unwanted areas, thus assisting in transfer.

[0207] Please see Figure 24 In some embodiments, step S110, which involves placing a solution containing a plurality of LED chips onto the substrate, includes placing the solution into a region where multiple electrode units are located. This allows the solution to be placed onto the substrate 10 indiscriminately, filling the region where the substrate 10 is located and completely immersing the substrate 10 in the solution. The advantage of this is that no printing process is required, and transfer can be achieved relatively simply. In this embodiment, structures that constrain solution flow can also be provided near the electrode regions on the substrate 10, such as raised edges along the periphery of each electrode region to constrain solution flow. This prevents the LED chips 20 in the solution from easily flowing outside the electrode regions, thus aiding in transfer.

[0208] After the LED chip 20 transfer process is completed, the solution is evaporated. At this point, there is only a weak connection between the LED chip 20 and the first, second, and third substrate electrodes 11, 12, and 13, and the contact resistance is random. Some LED chips 20 may have higher contact resistance, leading to uneven display. Simultaneously, because there is only a weak connection between the LED chip 20 and the substrate 10, moving the substrate 10 at this time may cause the LED chip 20 to shift, disrupting the transfer effect and reducing the transfer yield. Therefore, to solve this problem, a bonding method that focuses on strengthening the connection between the LED chip 20 and the substrate electrodes on the substrate 10 will be proposed below, thus obtaining a bonded LED chip.

[0209] It should be noted that the various embodiments of the LED chip bonding method are illustrated using the example of an electrode unit including three types of substrate electrodes. The implementation method of an electrode unit including two types of substrate electrodes is actually similar to that including three types of substrate electrodes, so it will not be described again.

[0210] Please see Figure 25The first solution is as follows: In step S110, the substrate 10 is immersed in a solution containing a number of LED chips. Photoresist is mixed into the solution. After the solution evaporates, the bonded LED chips 20 placed on the substrate 10 are coated with a layer of photoresist (i.e., a photoresist layer) 104. Due to the presence of the photoresist layer 104, the position of the LED chips 20 is fixed and will not shift due to the movement of the substrate 10, thus forming effective electrical contact and mechanical protection.

[0211] Photoresist can be either positive or negative. The concentration of photoresist cannot be too high, otherwise the solution's fluidity will decrease, hindering transfer. The concentration cannot be too low, otherwise it will be insufficient to fix the chip and support subsequent processes. Generally, the mass ratio of photoresist to solution is between 0.05 and 0.25.

[0212] During the transfer process, after the LED chip 20 has moved sufficiently, the solution is heated. This heating simultaneously evaporates the solvent and cures the photoresist. The preferred heating temperature for the photoresist is 100℃ to 140℃, and a solvent with a boiling point below this temperature, such as ethanol, should be selected. The preferred baking time is 30 seconds to 10 minutes.

[0213] The second solution: To further strengthen the electrical connection between the LED chip 20 and the substrate 10, a metal layer 105 can be deposited between the two chip electrodes of the LED chip 20 and the first, second, and third substrate electrodes 11, 12, and 13. Photoresist is a necessary process during the deposition of the metal layer 105; therefore, pre-coating with photoresist can save a step in the photolithography process. Furthermore, compared to common processes such as spin coating for photoresist placement, the photoresist applied using the first solution described above is more uniform.

[0214] Specifically, based on the first solution, after step 130 of heating to evaporate the solution, the transfer method further includes:

[0215] Please see Figure 26 and Figure 27 The photoresist covering the two chip electrodes of the LED chip 20 and the photoresist between adjacent LED chips 20 are removed by exposure, while the photoresist on the upper surface of the LED chip 20 is retained, thus exposing the two chip electrodes of the LED chip 20 and the substrate electrodes 11, 12, and 13.

[0216] Specifically, in this process, the photoresist layer 104 is selectively exposed, with the exposed area coinciding with the areas where the first, second, and third substrate electrodes 11, 12, and 13 are located. Next, the exposed area is removed. The effect is as follows. Figure 27 As shown.

[0217] Please see Figure 28A metal layer 105 is formed on the first surface of the LED chip 20 and the backplane by metal deposition. Specifically, the thickness of the deposited metal layer 105 is slightly thinner than the thickness of the photoresist layer 104. Besides electroplating, the metal can also be deposited by vapor deposition or sputtering.

[0218] Please see Figure 29 The photoresist deposited on the LED chip 20 is removed, and a metal connection is formed between the two chip electrodes of the LED chip 20 and the corresponding substrate electrodes of the substrate 10. The effect is as follows: Figure 29 As shown, since the photoresist layer 104 is removed, the metal layer 105 above the photoresist layer 104 is also removed. This creates a metal connection between the LED chip 20 and the first, second, and third substrate electrodes 11, 12, and 13. These metals effectively reduce the contact resistance between the LED chip 20 and the substrate 10, and also provide a stronger fixing force between the LED chip 20 and the substrate electrodes. Figure 29 In the case shown, the thickness of the deposited metal layer 105 exceeds the width of the LED chip 20.

[0219] It is understandable that the thickness of the deposited metal layer 105 can also be less than the width of the LED chip 20, such as... Figure 30 As shown, since the LED chip 20 already has chip electrodes at both ends, during the deposition of the metal layer 105, the newly deposited metal will fuse with the two chip electrodes of the LED chip 20 to form a whole. Therefore, even if the thickness of the metal layer 105 is less than the width of the LED chip 20, effective electrical contact and mechanical protection can still be formed.

[0220] The third solution to the above problem is as follows: In step S110, the substrate is immersed in a solution containing LED chips 20. This solution does not contain photoresist, but rather flux as a fixative. The flux can be rosin, or a rosin-resin-based flux composed of resin, halogenated activators, additives, and organic solvents. Simultaneously, when setting the substrate electrodes, a layer of soldering material 106, such as tin (Sn) or indium (In), is first applied over the substrate electrodes. The weight ratio of flux to solution ranges from 0.1 to 0.3. The process temperature varies depending on the soldering material 106.

[0221] Step S130, heating to evaporate the solution, includes:

[0222] Please see Figure 31 The solution is pre-evaporated to evaporate a portion of the solution.

[0223] The pre-evaporation of the heated solution is to perform a first-stage evaporation treatment on the solution. After the first-stage evaporation treatment, the volume of the solution is reduced to 0.1 to 0.5 times the original volume, that is, the volume of the solution after evaporation is 0.1 to 0.5 times the volume of the solution before evaporation.

[0224] Please see Figure 32 After the solution undergoes a first-stage evaporation process, the substrate 10 is heated to enter the welding process, causing the two chip electrodes of the LED chip 20 and the first, second, and third substrate electrodes 11, 12, and 13 on the substrate 10 to fuse with the welding material 106. Subsequently, the solution undergoes a second-stage evaporation process to evaporate the remaining solution. Thus, when the transfer of the LED chip 20 is complete, the two chip electrodes of the LED chip 20 rest on the welding material 106 of the two substrate electrodes, and the two chip electrodes of the LED chip 20 are in direct contact with the welding material 106, thereby forming effective electrical contact and mechanical protection.

[0225] The two chip electrodes of LED chip 20 fuse with the welding material to achieve electrical contact. The high temperature is maintained for a certain period of time. After welding is completed, the temperature is lowered to room temperature, and the welding is finished.

[0226] In the above and other embodiments, the implementation steps can be flexibly varied under the same concept of this solution. For example, another staged LED chip 20 welding reinforcement process:

[0227] Phase 1: The solution is plentiful and the concentration is low, allowing the LED chips 20 to move freely. This process allows the LED chips 20 to move fully and be arranged as evenly as possible on the backplate; specifically, the solution can be gently shaken (i.e., disturbed), generally lasting 10s to 600s. Phase 1 ends when the LED chips 20 are roughly evenly distributed.

[0228] Phase Two: At this stage, the arrangement of LED chips 20 is basically complete. Some of the solution is evaporated to make the LED chips 20 less prone to movement, and then the heating and soldering process begins. Specifically, the solution is first heated to evaporate it, reducing its volume to 0.1 to 0.5 times its original size. Then, the heating and soldering process is carried out, typically at 150°C to 300°C for 2 to 30 minutes. Taking Sn as an example, the preferred process temperature is between 220°C and 250°C, with a continuous heating time of 15 to 20 minutes.

[0229] In another embodiment, the two-stage heating and evaporation treatment of the solution in the above embodiment can be carried out continuously in one go, without a clear boundary between the first and second stages.

[0230] The fourth solution to the above problem involves introducing metal ions into the solution instead of photoresist or flux. These metal ions can be nickel, gold, copper, cadmium, etc. (for electroplating elemental electrodes), or a mixture thereof (for electroplating alloy electrodes). The concentration range of the metal ions is 10. -2 mol / L to 10 1 mol / L.

[0231] Because the pixel structure contains first, second, and third substrate electrodes 11, 12, and 13, one can be connected to the positive terminal of the power supply, and the other two to the negative terminal, or one to the negative terminal and the other two to the positive terminal. This creates a voltage difference between the different types of substrate electrodes. When the electrodes are energized, metal ions are deposited on the two chip electrodes of the LED chip and the surfaces of the first, second, and third substrate electrodes 11, 12, and 13, achieving an electroplating effect. Alternatively, the above pixel structure driving method can be used to apply power to the electrodes on the substrate 10 to perform the electroplating process. When the electroplating time is long enough, the metal on the surfaces of the first, second, and third substrate electrodes 11, 12, and 13 will connect with the two chip electrodes of the LED chip 20, as shown below. Figure 33 As shown, the bonded LED chip is obtained. After the transfer is completed, the metal layer 105 can be deposited without moving the substrate 10, achieving good electrical contact and mechanical fixation.

[0232] Please see Figure 33 In step S130, the solution is heated to evaporate, which involves pre-evaporating the solution to evaporate a portion of it. This first-stage evaporation process reduces the solution volume to 0.1 to 0.5 times its original volume. Subsequently, the two chip electrodes of the LED chip 20 are coated with a metal layer by electroplating. A second-stage evaporation process is then performed to evaporate the remaining solution.

[0233] In another embodiment, the electroplating process for depositing metal in the second and fourth solutions described above belongs to the same concept as this solution, and the implementation steps can be flexibly varied. For example, another staged electroplating process described above:

[0234] Phase 1: The solution is plentiful and the concentration is low, allowing the LED chips 20 to move freely. This process allows the LED chips 20 to move fully and be arranged as evenly as possible on the backplate; specifically, the solution can be gently shaken (i.e., disturbed), generally for 10s to 600s. Phase 1 ends when the LED chips 20 are roughly evenly distributed.

[0235] In Phase Two, the arrangement of the LED chips 20 is basically complete. Phase Two involves first heating and evaporating the solution, reducing its volume to 0.1 to 0.5 times its original size. Then, an electroplating current is applied for electroplating. Copper ions are preferred for electroplating, and the preferred time is 5 to 30 minutes.

[0236] In addition, during the electroplating process described above, the electroplating rate should be controlled between 0.4 micrometers per minute and 0.6 micrometers per minute, and the time should generally not exceed one hour. If the pixel structure is stacked, the substrate electrodes can protect the driving circuit 30 of the TFT area from damage during the electroplating process. If the pixel structure has the electrode units and the TFT area placed side by side on the upper surface of the substrate 10, a dense intermediate insulating layer 102 should be fabricated above the TFT area (this intermediate insulating layer 102 has the same process requirements as the upper insulating layer 101 and the lower insulating layer 103 of the stacked structure), with a thickness of not less than 1 micrometer, to protect the TFT area.

[0237] The advantage of using electroplating to fabricate electrode reinforcement connections is that it eliminates the need for photolithography and alignment, automatically depositing a metal layer 105 on the areas with substrate electrodes. Furthermore, the deposited metal layer 105 is less likely to creep onto the non-metallic parts of the LED chip 20, preventing light blockage. This process results in higher light extraction efficiency for the LED chip 20.

[0238] In some embodiments, prior to step S130, the transfer method further includes applying power to the first, second, and third substrate electrodes 11, 12, and 13 to automatically align (i.e., self-assemble) the plurality of LED chips, thereby connecting two chip electrodes of the plurality of LED chips 20 to any two of the at least two types of substrate electrodes. Applying power to the first, second, and third substrate electrodes 11, 12, and 13 is similar to the method of applying power to the electrodes on the substrate 10 in the pixel structure driving method described above. This step can also be added to the transfer methods of the above embodiments to improve the transfer efficiency of the LED chips.

[0239] If each electrode region is selectively placed on the substrate 10, and a solution containing red (R), green (G), and blue (B) LED chips 20 is placed therein, ensuring that they do not permeate each other, and these LED chips are arranged using any of the bonding methods described in Embodiment 1 and the first, second, third, and fourth solutions for strengthening the chip electrodes, then each pixel can emit light in three colors without the need for color conversion. In this method, the LED chips 20 can be implemented using the aforementioned type A gallium nitride-based LED chips to create BG chips, and type A gallium arsenide-based LED chips to create R chips, or type B LED chips with their own color coating layer 7.

[0240] If the LED chip 20 placed in each electrode region is not the target emission color, color conversion is required. The following provides several color conversion methods based on the premise that each region corresponds to one electrode unit. Specifically, if each region corresponds to one electrode unit, then step S110, which involves placing a solution containing several LED chips into the substrate, includes placing the solution into each region separately. The color conversion scheme is explained as follows:

[0241] The first method for color conversion involves immersing each region in a solution containing photoresist and a light-converting material; heating to evaporate the solution; and coating the outer surface of the LED chip 20 with the photoresist and light-converting material. Therefore, please refer to... Figure 34 The upper surface of the substrate 10 after being immersed in the solution is covered with a photoresist layer 104 containing a light conversion material.

[0242] Specifically, in this step, in addition to the blue LED chip 20 (using a type B LED chip or a gallium nitride-based LED chip), the solution also contains a light conversion material and photoresist. The light conversion material can be quantum dots or phosphors. The solution uses... Figure 23 The selective placement method shown is used to print onto specific electrode regions. The R and G electrode regions are printed with a solution of light-conversion material of the corresponding color, while the B electrode region does not contain light-conversion material but may contain photoresist. (See [link to documentation]). Figure 40 .

[0243] After heating to evaporate the solution in step S130, the method further includes:

[0244] First, the photoresist layer 104 covering the two chip electrodes of the LED chip 20 and the adjacent LED chip 29 is removed by exposure, so that the two chip electrodes of the LED chip 20 and the substrate electrode are exposed.

[0245] Specifically, please refer to Figure 35In this example, the photoresist in the irradiated area is cured. The cured area is the gap between the substrate electrodes, or slightly larger than the gap between the substrate electrodes, to increase color conversion and light extraction efficiency. Next, the photoresist layer 104 with light conversion material in the unirradiated area is removed, with the effect as follows. Figure 36 As shown. The mass ratio of the light conversion material to the solution is between 0.01 and 0.1. The photoresist should be a material that becomes transparent after curing, meaning that the photoresist is transparent after curing and will not block light.

[0246] Subsequently, a metal layer 105 is formed between the two chip electrodes of the LED chip 20 and the substrate electrodes in the electrode region by metal deposition. Please refer to... Figure 37 In this example, the thickness of metal layer 105 is greater than the diameter of LED chip 20; please refer to... Figure 38 In this example, the thickness of the metal layer 105 is smaller than the diameter of the LED chip 20. Please refer to the preceding text for the specific principles and functions of the two settings. Figure 29 , Figure 30 Description of related embodiments.

[0247] The second light-emitting color conversion scheme: Unlike the first light-emitting color conversion scheme, light conversion material is printed onto the regions (electrode units) before the solution is placed into each region.

[0248] Then, a solution containing photoresist is placed into each area. The solution can be... Figure 23 The selective placement method shown is used to print onto specific electrode areas, and it can also be used... Figure 24 The method of placing the substrate 10 indiscriminately as shown allows the substrate 10 to be immersed in the solution.

[0249] After heating to evaporate the solution in step S130, please refer to... Figure 39 The outer surface of the LED chip 20 is covered with a photoresist layer 104 containing light conversion material.

[0250] In an optional embodiment, the region includes an R electrode region, a G electrode region, and a B electrode region. Then, printing light conversion material onto the region first includes:

[0251] Light conversion materials were printed into the R electrode region and the G electrode region, respectively.

[0252] In step S130, after heating to evaporate the solution, the outer surfaces of the LED chips in the R and G electrode regions are coated with an R color conversion layer 107 and a G color conversion layer 108 formed of photoresist and light conversion material. The outer surface of the LED chip in the B electrode region is coated with a photoresist layer 104 formed of photoresist. Please refer to [link to relevant documentation]. Figure 40 .

[0253] Finally, after step 130, the following is also included:

[0254] Please see Figure 35 , 36 The photoresist outside the upper surface of the LED chip 20 is removed by exposure.

[0255] Please see Figure 37 , 38 A metal layer 105 is formed between the two chip electrodes of the LED chip and the substrate electrode in the electrode region by metal deposition.

[0256] The third color conversion scheme: In step S110, the substrate is immersed in a solution containing LED chips. The solution includes a first solution, a second solution, and a third solution. The first solution also contains a first light conversion material (red), photoresist, and metal ions; the second solution contains a second light conversion material (green), photoresist, and metal ions; and the third solution also contains photoresist and metal ions. The regions include an R electrode region, a G electrode region, and a B electrode region. Placing the substrate in step S110 includes: immersing the first solution in the R electrode region; immersing the second solution in the G electrode region; and immersing the third solution in the B electrode region. It should be noted that the R electrode region may be prepared for connecting a red-emitting LED chip, the B electrode region may be prepared for connecting a blue-emitting LED chip, and the G electrode region may be prepared for a green-emitting LED chip. Furthermore, the first, second, and third solutions can each be one or more of deionized water, toluene, xylene, methanol, ethanol, isopropanol, etc., and there are no restrictions on this.

[0257] In one example, red quantum dots (or phosphors) are added to the first solution as the first light conversion material, and green quantum dots (or phosphors) are added to the second solution as the second light conversion material.

[0258] Specifically, the heating step S130 to evaporate the solution includes: firstly, performing a first-stage pre-evaporation on the solution placed on the substrate 10 to evaporate a portion of the solution; then, please refer to... Figure 33Similar to the fourth solution for electrode reinforcement described above: after the first stage of evaporation of the solution, a power source is applied to the substrate electrodes of at least two types of substrate electrodes to perform an electroplating process, so that the two chip electrodes of the LED chip 20 and the substrate electrodes are covered with a metal layer 105, thereby forming a relatively fixed electrical connection between the two chip electrodes of the LED chip 20 and the first, second, and third substrate electrodes 11, 12, and 13. Pre-evaporation involves evaporating a portion of the solution, making it difficult for the LED chip 20 to detach from the substrate, but with sufficient solution for electroplating. Electroplating is performed on the first, second, and third substrate electrodes 11, 12, and 13 using the fourth bonding solution method described earlier (because the solution contains metal ions), and the plated metal layer 105 covers the chip electrodes of the LED chip 20. After heating and evaporating the remaining solution... Figure 40 The image shown is a schematic diagram of the effect of a region containing one pixel.

[0259] Additionally, when electroplating is required, it is important to appropriately increase the concentration of the light conversion material. This is because the metal deposition process may introduce light conversion material onto the substrate electrodes, leading to a decrease in its concentration. Since the substrate electrodes are not transparent, this mixing does not affect screen performance; however, the concentration of the light conversion material should be appropriately increased to compensate for the decrease in concentration during electroplating.

[0260] The fourth color conversion scheme: Within each pixel area, light-emitting units of three colors—R, G, and B—need to be fabricated. Since the solution added in step S110 in this example contains a monochromatic LED chip, such as blue, color conversion is required for two electrode areas (R electrode area and G electrode area). In one example, the color conversion includes the following process:

[0261] In the first stage, the only light conversion material mixed into the solution is red quantum dots (or phosphors). Therefore, after the solution evaporates, the entire substrate 10 can be covered with an R-color conversion layer 107 composed of red quantum dots. In the second stage, the R-color conversion layer 107 can be selectively removed by photolithography, leaving only the R-color conversion layer 107 in the R electrode region.

[0262] In the third stage, green light conversion material is placed onto the G electrode region using conventional quantum dot printing methods to form the G color conversion layer 108. This reduces the fabrication process of the color conversion material by one step. Figure 40 The image shown is a schematic diagram of the effect of a region containing one pixel.

[0263] The fifth emission color conversion scheme: Please refer to [link / reference]. Figure 41Alternatively, instead of distinguishing between the three colors of light conversion materials, a mixture of two other color conversion materials with different colors emitted by the mixed LED chip 20 can be applied to all pixel areas. For example, the mixed LED chip 20 could be a blue LED chip, and the mixture could be an RG color conversion layer 110. This method simplifies the process, and the composition of the color conversion materials and the thickness of the color conversion layer should ensure that the converted and transmitted light simultaneously have RGB components. To achieve three colors, a filter film corresponding to the emitted color needs to be placed above the color conversion layer in each electrode area: a G filter film 111 on the G electrode area, an R filter film 112 on the R electrode area, and a B filter film 113 on the B electrode area. Furthermore, to prevent interference between adjacent colors, a light-shielding layer 115 should be created between different light-emitting (electrode) areas to block the light.

[0264] In step S110, the substrate is placed in a solution containing a plurality of LED chips. The solution contains photoresist and a light conversion material. The upper surface of the substrate 10 is coated with photoresist containing the light conversion material. Please refer to... Figure 41 After the solution evaporates in step S130, the transfer method further includes: setting a light-shielding layer 115 between each electrode unit; and setting a filter film 111-113 of a predefined color on each electrode unit. In other embodiments, when the substrate 10 is placed in the solution in step S110, metal ions, flux, etc. may also be mixed in to strengthen the connection strength between the LED chip 20 and the substrate electrode.

[0265] In the above embodiments, a substrate 10 with three types of substrate electrodes is used as an example to illustrate the various manufacturing processes. It is understood that the various steps of the above embodiments are also applicable to substrates 10 with two or more types of substrate electrodes, and will not be described in detail here. In addition, the above embodiments mention that the LED chip 20 mixed with solution mostly uses blue LED chips. It is understood that the emission color of the LED chip 20 mixed with solution can be arbitrarily selected according to application requirements, cost, etc. After selecting the emission color of the LED chip 20 mixed with solution, the light-emitting area that needs to be color-converted can be selected with a light conversion material of a suitable color according to the situation. Those skilled in the art can match it according to their needs, and will not be described in detail here.

[0266] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for transferring an LED chip, characterized in that, include: A substrate is provided, and a solution containing LED chips is placed on the substrate. The solution flows freely on the substrate, causing the LED chips to move randomly. The substrate is provided with a plurality of electrode units, each electrode unit including first substrate electrodes and second substrate electrodes arranged at intervals. All substrate electrodes on the substrate are arranged in a matrix in space, wherein multiple of one type of substrate electrode surround one of another type of substrate electrode. The minimum distance between any two first substrate electrodes on the substrate is greater than the minimum distance between any two first substrate electrodes and second substrate electrodes on the substrate. The LED chip includes a chip body and two chip electrodes spaced apart on the chip body, wherein the distance between the two chip electrodes of the LED chip is greater than the minimum distance between any two adjacent substrate electrodes. The solution is heated to evaporate, thereby placing the LED chip on the substrate.

2. The transfer method as described in claim 1, characterized in that, The solution also contains photoresist, and after the solution is heated to evaporate, the LED chip placed on the substrate is coated with a photoresist layer.

3. The transfer method as described in claim 2, characterized in that, The transfer method further includes: The photoresist coating on the two chip electrodes of the LED chip and between adjacent LED chips is removed by exposure. A metal layer is formed on the LED chip and the substrate by metal deposition. The photoresist deposited on the LED chip is removed, and a metal connection is formed between the two chip electrodes of the LED chip and the corresponding substrate electrodes.

4. The transfer method as described in claim 1, characterized in that, The solution also contains metal ions, and the heating to evaporate the solution includes: The solution is pre-evaporated to evaporate a portion of the solution; Electroplating is used to cover the two chip electrodes of the LED chip and the substrate electrode with a metal layer. Evaporate the remaining solution.

5. The transfer method as described in claim 1, characterized in that, The solution contains flux, and the substrate is also covered with soldering material. The heating to evaporate the solution includes: The solution is subjected to a first-stage evaporation process; The substrate is heated to fuse the two chip electrodes of the LED chip, the substrate electrodes, and the welding material. Evaporate the remaining solution to dryness.

6. The transfer method as described in claim 1, characterized in that, The substrate has several regions, each region corresponding to one electrode unit, and the step of placing the solution containing the LED chip into the substrate includes: The solution is then placed into each of the aforementioned regions.

7. The transfer method as described in claim 6, characterized in that, The solution contains photoresist, and before immersing the solution into each of the regions, the method further includes: Print light conversion material into the area; The heating to evaporate the solution includes: The solution is heated to evaporate it, and the outer surface of the LED chip is coated with photoresist and the light conversion material.

8. The transfer method as described in claim 7, characterized in that, The region includes an R electrode region, a G electrode region, and a B electrode region; the printing of light conversion material into the region includes: The light conversion material is printed onto the R electrode region and the G electrode region, respectively. The heating to evaporate the solution includes: The solution is heated to evaporate it. The outer surfaces of the LED chips in the R electrode region and the G electrode region are coated with the photoresist and the light conversion material, and the outer surface of the LED chip in the B electrode region is coated with the photoresist.

9. The transfer method as described in claim 8, characterized in that, After heating to evaporate the solution, the process further includes: The photoresist between the two chip electrodes of the LED chip and between adjacent LED chips is removed by exposure. A metal layer is formed between the two chip electrodes of the LED chip and the electrodes in the electrode region by metal deposition.

10. The transfer method as described in claim 6, characterized in that, The solution includes a first solution, a second solution, and a third solution. The first solution further contains a first light conversion material, photoresist, and metal ions. The second solution contains a second light conversion material, photoresist, and metal ions. The third solution further contains photoresist and metal ions. The region includes an R electrode region, a G electrode region, and a B electrode region. Placing the substrate with the solution containing the LED chip includes: The first solution is placed into the R electrode region; The second solution is placed into the G electrode region; The third solution is placed into the B electrode region.

11. The transfer method as described in claim 10, characterized in that, The heating to evaporate the solution includes: The solution is pre-evaporated to evaporate a portion of the solution; Electroplating is used to cover the two chip electrodes of the LED chip and the substrate electrode with a metal layer. The remaining solution is evaporated by heating.

12. The transfer method according to any one of claims 1 to 11, characterized in that, The two chip electrodes of the LED chip are respectively wrapped around the two ends of the chip body.

13. The transfer method as described in claim 1, characterized in that, The plurality of substrate electrodes include a first substrate electrode and a second substrate electrode, wherein the first substrate electrode and the second substrate electrode on the substrate are arranged alternately in the longitudinal direction and alternately in the transverse direction.

14. The transfer method as described in claim 13, characterized in that, The cross-sectional shape of the first substrate electrode and the second substrate electrode is an equilateral triangle. The ratio of the minimum distance between the first substrate electrode and the second substrate electrode to the side length of the equilateral triangle is in the range of 0.005 to 0.

05. The ratio of the side length of the equilateral triangle to the distance between the two chip electrodes of the LED chip is in the range of 0.1 to 1.

15. The transfer method as described in claim 13, characterized in that, The cross-sectional shape of the first substrate electrode and the second substrate electrode is square. The ratio of the minimum distance between the first substrate electrode and the second substrate electrode to the side length of the square is in the range of 0.01 to 0.

1. The ratio of the side length of the square to the distance between the two chip electrodes of the LED chip is in the range of 0.2 to 1.

4.

16. The transfer method as described in claim 13, characterized in that, The cross-sectional shape of the first substrate electrode and the second substrate electrode is square, and the distance between the two chip electrodes of the LED chip is less than the sum of the side length of the square and the minimum distance between the first substrate electrode and the second substrate electrode.

17. The transfer method according to any one of claims 13 to 16, characterized in that, The minimum spacing between adjacent electrode units is equal to the minimum distance between the first substrate electrode and the second substrate electrode between the electrode units.

18. The transfer method as described in claim 13, characterized in that, The plurality of substrate electrodes further includes a third substrate electrode, wherein any one of the first substrate electrode, the second substrate electrode and the third substrate electrode on the substrate is adjacent to the other two substrate electrodes respectively.

19. The transfer method as described in claim 18, characterized in that, The cross-sectional shape of the first substrate electrode, the second substrate electrode, and the third substrate electrode is circular. The ratio of the minimum distance between the first substrate electrode and the second substrate electrode to the diameter of the circle is in the range of 0.01 to 0.

1. The ratio of the diameter of the circle to the distance between the two chip electrodes of the LED chip is in the range of 0.6 to 2.

20. The transfer method as described in claim 18, characterized in that, The cross-sectional shape of the first substrate electrode, the second substrate electrode, and the third substrate electrode is a regular hexagon. The ratio of the minimum distance between the first substrate electrode and the second substrate electrode to the side length of the regular hexagon is in the range of 0.05 to 0.

2. The ratio of the side length of the regular hexagon to the distance between the two chip electrodes of the LED chip is in the range of 0.2 to 2.

21. The transfer method as described in claim 18, characterized in that, The minimum distance between the first substrate electrode, the second substrate electrode, and the third substrate electrode in the electrode unit is the same, and the minimum spacing between adjacent electrode units is equal to the minimum distance between the first substrate electrode and the second substrate electrode in the electrode unit.

22. The transfer method according to any one of claims 1-11, 13-16, and 18-21, characterized in that, In two adjacent substrate electrodes, a pair of finite grooves are formed from the middle of one electrode toward the middle of the other electrode.

23. The transfer method as described in claim 22, characterized in that, The sum of the length of the limiting groove pair and the minimum distance between the two adjacent substrate electrodes is 1.05 to 1.3 times the distance between the two chip electrodes of the LED chip.

24. The transfer method according to any one of claims 1 to 11, characterized in that, The solution includes one or more of deionized water, toluene, xylene, methanol, ethanol, and isopropanol.

25. The transfer method as described in claim 1, characterized in that, The chip body is a cylinder, and the two chip electrodes are spaced apart on the side of the cylinder.

26. The transfer method as described in claim 25, characterized in that, The chip electrode has a ring-shaped structure, and the difference between the outer diameter of the chip electrode and the radius of the chip body is greater than 0 and less than 3 mm.

27. The transfer method as described in claim 26, characterized in that, The spacing between the two chip electrodes is equal to the difference between the distance between the two ends of the chip body and the width between the two chip electrodes.

28. The transfer method as described in claim 1, characterized in that, The chip body is a cylinder, and the two chip electrodes are spaced apart at the two ends of the cylinder, with the distance between the chip electrodes being equal to the distance between the two ends of the cylinder.

29. The transfer method as described in claim 1, characterized in that, The chip body is a cylinder, and the two chip electrodes respectively cover the ends of the cylinder.

30. The transfer method as described in claim 1, characterized in that, The chip body is a prism, and the two chip electrodes are spaced apart on the side of the prism. The chip electrodes include multiple chip sub-electrodes, the number of which is equal to the number of side edges of the prism. Each chip sub-electrode protrudes from one side of the chip body, forming a corresponding ring array.

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