Transfer method of LED chip and display panel

Abstract

The present application relates to a kind of transfer method of LED chip.It includes: providing display backboard, including magnetic shielding layer, substrate, at least one first sub-pad group and adhesive layer;Providing the first transfer plate with at least one first LED chip, the first electrode group of first LED chip is covered with first magnetic conductive layer;First LED chip is at least partially embedded in adhesive layer;Each first sub-pad group is applied with electric signal to generate magnetic field;Peel off the first LED chip to be transferred from the first transfer plate, first magnetic conductive layer is under the action of magnetic force in the direction perpendicular to substrate and leads first LED chip to move to first sub-pad group, until first electrode group is attached with corresponding first sub-pad group.The present application also provides a kind of display panel.The LED chip transfer method and display panel provided by the present application, LED chip is fixed to display backboard by magnetic force adsorption and adhesive force, and LED chip does not occur displacement when being peeled off.

Description

Technical Field

[0001] This application relates to the field of semiconductor light-emitting technology, and in particular to a method for transferring LED chips and a display panel. Background Technology

[0002] Light-emitting diodes (LEDs) have been widely used in many lighting and display fields due to their excellent characteristics such as high luminous efficiency, high reliability, and flexible size assembly, especially in large-size display applications such as outdoor billboards, stage backdrops, and large text broadcast screens. The next development trend for LED displays is to miniaturize LED chips to the micrometer size (i.e., Micro-LED), to replace existing LCD and OLED displays in small and medium-sized display applications such as indoor televisions, mobile phone displays, and wearable devices.

[0003] The realization of Micro-LED full-color display mainly relies on the mass transfer technology of Micro-LED chips. Currently, during the process of transferring Micro-LED chips to the display backplane, the Micro-LED chips are prone to displacement when they are peeled off from the transfer board, which causes the corresponding positions of the LED chips and the display backplane to be misaligned, resulting in low transfer yield. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this application is to provide a method for transferring LED chips and a display panel. By using the magnetic attraction of the LED chip to the display backplate and the adhesive force of the adhesive layer of the display backplate to the LED chip, the LED chip will not be displaced under the combined action of magnetic force and adhesive force when it is peeled off from the transfer plate. This allows for precise alignment and bonding with the corresponding position of the display backplate, thereby improving the transfer efficiency and yield of the LED chip.

[0005] A method for transferring an LED chip includes: providing a display backplane, the display backplane including a magnetic shielding layer, a substrate, at least one pad group, and an adhesive layer, the magnetic shielding layer being disposed on a first side of the substrate, the pad group being disposed on a second side of the substrate, the pad group including at least one first sub-pad group, the first side and the second side of the substrate being disposed opposite to each other, the adhesive layer being disposed on the second side of the substrate and covering the pad group; providing a first transfer plate, the first transfer plate carrying at least one first LED chip, a first electrode group of the first LED chip being covered with a first magnetic conductive layer; embedding the first LED chip at least partially into the adhesive layer, wherein the first LED chip to be transferred is aligned with the corresponding first sub-pad group; applying an electrical signal to each of the first sub-pad groups to generate a magnetic field located on the second side of the substrate; and peeling the first LED chip to be transferred off the first transfer plate, wherein the first magnetic conductive layer, under the action of a magnetic force perpendicular to the substrate, drives the first LED chip to move toward the corresponding first sub-pad group until the first electrode group adheres to the corresponding first sub-pad group.

[0006] The above-mentioned LED chip transfer method utilizes the magnetic attraction of the display backplate to the first LED chip and the adhesive force of the adhesive layer to the first LED chip, so that when the first LED chip is peeled off from the first transfer plate, the first LED chip will not be displaced under the combined action of magnetic force and adhesive force, thereby accurately aligning and adhering to the corresponding position of the display backplate, improving the transfer efficiency and yield of the first LED chip.

[0007] Optionally, the first sub-pad group includes a positive pad and a negative pad. Applying an electrical signal to each of the first sub-pad groups to generate a magnetic field located on the second side of the substrate includes: applying a first electrical signal and a second electrical signal to the positive pad and the negative pad respectively, so that a voltage difference is formed between the positive pad and the negative pad, and controlling the first electrical signal and the second electrical signal to make the voltage difference change periodically to generate a magnetic field located on the second side of the substrate.

[0008] Optionally, controlling the first electrical signal and the second electrical signal to cause the voltage difference to change periodically includes: controlling the first electrical signal and the second electrical signal to cause the voltage difference to increase periodically from a first voltage difference value to a second voltage difference value.

[0009] Optionally, after the first electrode group is bonded to the corresponding first sub-pad group, the method further includes: bonding the first electrode group, the first magnetic conductive layer, and the first sub-pad group.

[0010] Optionally, a sacrificial layer is provided between the first LED chip and the first transfer plate, and the step of peeling the first LED chip to be transferred from the first transfer plate includes: selectively irradiating the sacrificial layer located in the orthographic projection area of ​​the first LED chip to be transferred on the first transfer plate using a laser.

[0011] Optionally, the pad group further includes at least one second sub-pad group. After the first electrode group is bonded to the corresponding first sub-pad group, the method further includes: providing a second transfer plate, the second transfer plate carrying at least one second LED chip, the second electrode group of the second LED chip being covered with a second magnetic conductive layer, the emission color of the second LED chip being different from the emission color of the first LED chip; embedding the second LED chip at least partially into the adhesive layer, wherein the second LED chip to be transferred is aligned with the corresponding second sub-pad group; applying an electrical signal to each of the second sub-pad groups to generate a magnetic field located on the second side of the substrate; and peeling the second LED chip to be transferred from the second transfer plate, wherein the second magnetic conductive layer, under the action of a magnetic force perpendicular to the substrate direction, drives the second LED chip to move toward the corresponding second sub-pad group until the second electrode group is bonded to the corresponding second sub-pad group.

[0012] Optionally, the pad group further includes at least one third sub-pad group. After the second electrode group is bonded to the corresponding second sub-pad group, the method further includes: providing a third transfer board, the third transfer board carrying at least one third LED chip, the third electrode group of the third LED chip being covered with a third magnetic conductive layer, the emission color of the third LED chip being different from the emission colors of the first LED chip and the second LED chip; embedding the third LED chip at least partially into the adhesive layer, wherein the third LED chip to be transferred is aligned with the corresponding third sub-pad group; applying an electrical signal to each of the third sub-pad groups to generate a magnetic field located on the second side of the substrate; and peeling the third LED chip to be transferred from the third transfer board, the third magnetic conductive layer driving the third LED chip to move towards the corresponding third sub-pad group under the action of a magnetic force perpendicular to the substrate, until the third electrode group is bonded to the corresponding third sub-pad group.

[0013] Optionally, the transfer method further includes: bonding the first electrode group, the first magnetic conductive layer, and the first sub-pad group, and simultaneously bonding the second electrode group, the second magnetic conductive layer, and the second sub-pad group, and bonding the third electrode group, the third magnetic conductive layer, and the third sub-pad group.

[0014] Optionally, the first electrode group includes a positive electrode and a negative electrode. When the first electrode group is bonded to the corresponding first sub-pad group, the positive electrode is bonded to the positive pad and the negative electrode is bonded to the negative pad.

[0015] Based on the same inventive concept, the display panel includes a display back plate and at least one LED chip fixed to the display back plate, wherein the at least one LED chip is fixed to the display back plate using the aforementioned LED chip transfer method.

[0016] The aforementioned display panel uses the aforementioned LED chip transfer method to transfer at least one LED chip to the display back panel. Under the combined action of magnetic force and adhesive force, the at least one LED chip will not shift, thereby accurately aligning and adhering to the corresponding position of the display back panel, improving transfer efficiency and transfer yield. Attached Figure Description

[0017] Figure 1 A flowchart illustrating the LED chip transfer method provided in this application embodiment;

[0018] Figure 2 This is a cross-sectional schematic diagram of the display back panel provided in an embodiment of this application;

[0019] Figure 3 A cross-sectional schematic diagram of the first transfer plate provided in an embodiment of this application;

[0020] Figure 4 for Figure 1 A schematic diagram showing the positional relationship between the first transfer plate and the display backplate after step S103 is completed;

[0021] Figure 5 for Figure 1 A schematic diagram showing the positional relationship between the first LED chip and the display backplate after step S105 is completed;

[0022] Figure 6 This is a schematic diagram showing the positional relationship between the positive and negative electrode pads and the positive and negative electrodes.

[0023] Figure 7 This is a schematic diagram showing how the voltage difference between the positive and negative leads changes over time.

[0024] Figure 8 This is a schematic diagram showing the directions of the electric field, magnetic field, and magnetic force.

[0025] Figures 9 to 10 This is a schematic diagram illustrating the process of separating the first LED chip from the first transfer board, as provided in an embodiment of this application.

[0026] Figure 11A flowchart of an LED chip transfer method provided in another embodiment of this application;

[0027] Figure 12 A cross-sectional schematic diagram of the second transfer plate provided in an embodiment of this application;

[0028] Figure 13 for Figure 11 A schematic diagram showing the positional relationship between the second transfer plate and the display backplate after step S107 is completed;

[0029] Figure 14 for Figure 11 A schematic diagram showing the positional relationship between the second LED chip and the display backplate after step S109 is completed;

[0030] Figure 15 A flowchart of an LED chip transfer method provided in another embodiment of this application;

[0031] Figure 16 A cross-sectional schematic diagram of the third transfer plate provided in an embodiment of this application;

[0032] Figure 17 for Figure 15 A schematic diagram showing the positional relationship between the third transfer plate and the display backplate after step S110 is completed;

[0033] Figure 18 for Figure 15 A schematic diagram showing the positional relationship between the third LED chip and the display backplate after step S112 is completed.

[0034] Explanation of reference numerals in the attached figures:

[0035] 100 - Display back panel;

[0036] 110 - Magnetic shielding layer;

[0037] 120-Substrate;

[0038] 130 - Pad set;

[0039] 131 - First sub-pad group;

[0040] 1311 - Positive electrode pad;

[0041] 1312 - Negative electrode pad;

[0042] 132 - Second sub-pad group;

[0043] 133 - Third sub-pad group;

[0044] 140 - Adhesion layer;

[0045] 150 - Positive lead;

[0046] 160 - Negative lead;

[0047] 210 - First transfer plate;

[0048] 220 - First LED chip;

[0049] 221 - First electrode group;

[0050] 222 - First extensional structure;

[0051] 230 - First magnetic conductive layer;

[0052] 2211 - Positive electrode;

[0053] 2212 - Negative electrode;

[0054] 40-Sacrificial Layer;

[0055] 310 - Second transfer plate;

[0056] 320 - Second LED chip;

[0057] 321 - Second electrode group;

[0058] 322 - Second extensional structure;

[0059] 330 - Second magnetic conductive layer;

[0060] 410 - Third transfer plate;

[0061] 420 - Third LED chip;

[0062] 421 - Third electrode group;

[0063] 422 - Third extensional structure;

[0064] 430 - Third magnetic conductive layer. Detailed Implementation

[0065] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0066] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0067] In the description of this application, the terms "first," "second," "third," etc., are used to distinguish different objects, not to describe a specific order. In addition, the terms "upper," "lower," "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.

[0068] In the description of this application, unless otherwise expressly specified and limited, the term "connection" should be interpreted broadly. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0069] Please see Figure 1 , Figure 1 This is a flowchart of the LED chip transfer method provided in the embodiments of this application. Figure 2 This is a cross-sectional schematic diagram of the display back panel 100 provided in an embodiment of this application. Figure 3 This is a cross-sectional schematic diagram of the first transfer plate 210 provided in an embodiment of this application. Figure 4 for Figure 1 A schematic diagram showing the positional relationship between the first transfer plate 210 and the display back plate 100 after step S103 is completed. Figure 5 for Figure 1 A schematic diagram showing the positional relationship between the first LED chip 221 and the display backplate 100 after step S105 is completed. Figure 1 As shown, the LED chip transfer method includes the following steps:

[0070] S101: Provides, for example Figure 2 The display backplane 100 shown includes a magnetic shielding layer 110, a substrate 120, at least one pad group 130, and an adhesive layer 140. The magnetic shielding layer 110 is disposed on a first side of the substrate 120, and the at least one pad group 130 is disposed on a second side of the substrate 120. The pad group 130 includes at least one first sub-pad group 131. The first side and the second side of the substrate 120 are disposed opposite to each other. The adhesive layer 140 is disposed on the second side of the substrate 120 and covers the pad group 130.

[0071] S102: Provide as follows Figure 3The first transfer plate 210 shown has at least one first LED chip 220 on it, and the first electrode group 221 of the first LED chip 220 is covered with a first magnetic conductive layer 230.

[0072] S103: The first LED chip 220 is at least partially embedded in the adhesion layer 140, wherein the first LED chip 220 to be transferred is aligned with the corresponding first sub-pad group 131, as shown in the figure. Figure 4 As shown.

[0073] S104: Apply an electrical signal to each of the first sub-pad groups 131 to generate a magnetic field located on the second side of the substrate 120.

[0074] S105: The first LED chip 220 to be transferred is peeled off from the first transfer plate 210. Under the magnetic force perpendicular to the substrate 120, the first magnetic conductive layer 230 drives the first LED chip 220 to move towards the corresponding first sub-pad group 131 until the first electrode group 221 is attached to the corresponding first sub-pad group 131, as shown in the figure. Figure 5 As shown.

[0075] Steps S104 and S105 can be performed simultaneously, that is, while applying an electrical signal to the first sub-pad group 131, the first LED chip 220 to be transferred is peeled off from the first transfer plate 210. Alternatively, step S104 can precede step S105, that is, a magnetic field located on the second side of the substrate 120 is generated first, and then the first LED chip 220 to be transferred is peeled off from the first transfer plate 210.

[0076] In some embodiments, such as Figure 3 As shown, the first LED chip 220 also includes a first epitaxial structure 222, which is stacked on the first transfer plate 210 in sequence with the first electrode group 221.

[0077] The magnetic shielding layer 110 may be at least one of silicon steel sheet and CNTs / GO layer (graphene oxide / carbon nanotubes), used to shield the magnetic field located on the first side of the substrate 120. The adhesive layer 140 is a non-conductive adhesive layer, which may be made of polymer material, such as epoxy resin.

[0078] The magnetic conductive layer can be a magnetic metallic material, such as iron, nickel, or iron-nickel alloy.

[0079] The LED chip transfer method provided in this application utilizes the magnetic attraction of the display backplate 100 to the first LED chip 220 and the adhesive force of the adhesive layer 140 to the first LED chip 220. This ensures that when the first LED chip 220 is peeled off from the first transfer plate 210, the first LED chip 220 will not shift under the combined action of magnetic and adhesive forces. This allows for precise alignment and bonding with the corresponding position of the display backplate 100, improving the transfer efficiency and yield of the first LED chip 220.

[0080] Please see Figure 6 , Figure 6 This is a schematic diagram showing the positional relationship between the positive electrode pad 1311 and the negative electrode pad 1312 and the positive electrode 2211 and the negative electrode 2212. Figure 6 As shown, in some embodiments, the first sub-pad group 131 includes a positive electrode pad 1311 and a negative electrode pad 1312, and the first electrode group 221 includes a positive electrode 2211 and a negative electrode 2212. When the first electrode group 221 is attached to the corresponding first sub-pad group 131, the positive electrode 2211 is attached to the positive electrode pad 1311, and the negative electrode 2212 is attached to the negative electrode pad 1312. The materials of the positive electrode 2211, the negative electrode 2212, the positive electrode pad 1311, and the negative electrode pad 1312 can all be metallic materials, such as gold, indium, tin, copper, nickel, etc.

[0081] In the LED chip transfer method provided in this application, the positive electrode 2211 and the negative electrode 2212 of the first electrode group 221 are respectively covered with a first sub-magnetic conductive layer and a second sub-magnetic conductive layer. Under the action of magnetic force perpendicular to the direction of the substrate 120, the first sub-magnetic conductive layer and the second sub-magnetic conductive layer drive the positive electrode 2211 and the negative electrode 2212 to move toward the corresponding positive electrode pad 1311 and the negative electrode pad 1312, so that the positive electrode 2211 and the negative electrode 2212 are aligned and bonded with the corresponding positive electrode pad 1311 and the negative electrode pad 1312, respectively.

[0082] In some embodiments, applying an electrical signal to each of the first sub-pad groups 131 to generate a magnetic field located on the second side of the substrate 120 includes: applying a first electrical signal and a second electrical signal to the positive pad 1311 and the negative pad 1312 respectively, such that a voltage difference is formed between the positive pad 1311 and the negative pad 1312; and controlling the first electrical signal and the second electrical signal to make the voltage difference change periodically, so as to generate a magnetic field located on the second side of the substrate 120.

[0083] For details, please refer to the following document again. Figure 6 In some embodiments, the display backplane 100 further includes a positive lead 150 and a negative lead 160. The positive pad 1311 of the first sub-pad group 131 is connected to the positive lead 150, and the negative pad 1312 is connected to the negative lead 160. The negative lead 160 is grounded, and its voltage value is 0. The positive lead 150 is connected to a voltage input terminal, and the voltage difference between the positive lead 150 and the negative lead 160 is the voltage applied to the positive lead. A voltage value of 150 is established, creating a voltage difference between the positive lead 150 and the negative lead 160. This voltage difference between the positive pad 1311 and the negative pad 1312 generates an electric field. By periodically increasing the voltage difference between the positive lead 150 and the negative lead 160 over time, a magnetic field is generated between the positive pad 1311 and the negative pad 1312. This magnetic field covers the area between the first sub-pad group 131 and the first electrode group 221. When the first LED chip 220 is in the magnetic field, the first magnetic conductive layer 230 is subjected to a magnetic force perpendicular to the substrate 120.

[0084] For example, please refer to Figure 7 , Figure 7 This is a schematic diagram illustrating the change of the voltage difference V over time t, as shown below. Figure 7 As shown, the voltage difference V periodically increases from a first voltage difference A to a second voltage difference B, causing the intensity of the electric field between the positive electrode pad 1311 and the negative electrode pad 1312 to increase periodically. During this increase in electric field intensity, a magnetic field is generated between the positive electrode pad 1311 and the negative electrode pad 1312. The direction of this magnetic field can be determined by a right-hand screw method based on the direction of the electric field. The right-hand screw method involves extending the right thumb and placing it approximately perpendicular to the index finger, while bending the other four fingers. The thumb points in the direction of the electric field, and the bent four fingers point in the direction of the magnetic field.

[0085] Please refer to the direction of the electric field. Figure 8 , Figure 8 The direction of the electric field on the cross-sections of the positive electrode pad 1311 and the negative electrode pad 1312 is illustrated, as follows: Figure 8As shown, the direction X of the electric field is from the positive pad 1311 to the negative pad 1312. That is, the direction from the positive pad 1311 to the negative pad 1312 is the direction of the right thumb, and the direction of the four bent fingers of the right hand is perpendicular to the cross-section of the positive pad 1311 and the negative pad 1312 and inward. In other words, the direction of the magnetic field is perpendicular to the cross-section of the positive pad 1311 and the negative pad 1312 and inward, that is, perpendicular to the cross-section of the positive pad 1311 and the negative pad 1312. Figure 8 The paper is shown facing inwards. The cross-sections of the positive electrode pad 1311 and the negative electrode pad 1312 are planes intercepted by the line connecting their centers. These cross-sections are perpendicular to the substrate 120 and parallel to the line connecting their centers. When the first magnetic conductive layer 230 is in the magnetic field, the direction of the magnetic force experienced by the first magnetic conductive layer 230 is determined by the left-hand rule. The left-hand rule states that all five fingers are extended and approximately in the same plane, the right thumb and index finger are approximately perpendicular, the magnetic field passes through the palm of the left hand, the direction of the electric field is indicated by the extended four fingers of the left hand, and the direction of the magnetic force is indicated by the left thumb.

[0086] For details, please refer to the following document again. Figure 8 , Figure 8 The direction Z of the magnetic force experienced by the first magnetic conductive layer 230 in the magnetic field is also illustrated, such as... Figure 8 As shown, the direction Z of the magnetic force is perpendicular to the substrate 120 and is the direction in which the first magnetic conductive layer 230 approaches the substrate 120. The first magnetic conductive layer 230 is fixed relative to the first sub-pad group 131 on a plane parallel to the substrate 120 by the magnetic force in the Z direction, so that when the first LED chip 220 is peeled from the first transfer plate 210, the first LED chip 220 will not shift, thus allowing it to precisely adhere to the aligned first sub-pad group 131.

[0087] When the voltage difference V periodically decreases from the second voltage difference B to the first voltage difference A, a magnetic field with opposite directions is generated between the positive electrode pad 1311 and the negative electrode pad 1312. By setting the voltage difference V to change abruptly from the second voltage difference B to the first voltage difference A, that is, the time for the voltage difference V to decrease from the second voltage difference B to the first voltage difference A is very short, the first magnetic conductive layer 230 is in the magnetic field with opposite directions for a very short time, and the time for the first magnetic conductive layer 230 to be subjected to the magnetic force with opposite directions is very short, so that the first LED chip 220 will not move due to the magnetic force with opposite directions.

[0088] In some embodiments, a TFT (thin-film transistor) layer is disposed on the second side of the substrate 120. The TFT layer is connected to the pad group 130, the positive lead 150, and the negative lead 160, respectively. The TFT layer is used to selectively control the first sub-pad group 131 in the pad group 130 to be connected to the positive lead 150 and the negative lead 160 when a voltage is applied to the positive lead 150 and the negative lead 160. This results in an electric field being generated between the positive pad 1311 and the negative pad 1312 of the first sub-pad group 131 in the pad group 130, which in turn generates a magnetic field. This avoids the magnetic field direction generated by other pad groups in the pad group 130 other than the first sub-pad group 131 from affecting the magnetic field direction generated by the first sub-pad group 131.

[0089] In some embodiments, after the first electrode group 221 is bonded to the corresponding first sub-pad group 131, the method further includes: bonding the first electrode group 221, the first magnetic conductive layer 230, and the first sub-pad group 131. This can be achieved by heating the first electrode group 221, the first magnetic conductive layer 230, and the first sub-pad group 131, causing them to melt and bond together. For example, by controlling the bonding temperature to 600℃-800℃, the first electrode group 221, the first magnetic conductive layer 230, and the first sub-pad group 131 all melt and fuse at the bonding temperature, and by cooling the first electrode group 221, the first magnetic conductive layer 230, and the first sub-pad group 131, they are bonded together.

[0090] Please see Figures 9 to 10 , Figures 9 to 10This is a schematic diagram illustrating the process of separating the first LED chip 220 from the first transfer plate 210 according to an embodiment of this application. In some embodiments, a sacrificial layer 40 is provided between the first LED chip 220 and the first transfer plate 210. Step S105, described above, involves peeling the first LED chip 220 to be transferred from the first transfer plate 210, including: as... Figure 9 As shown, a laser is used to irradiate the first transfer plate 210 from the side away from the first LED chip 220 to be transferred. The area of ​​the laser irradiated on the first transfer plate 210 coincides with the orthographic projection of the first LED chip 220 to be transferred onto the first transfer plate 210. The laser removes the sacrificial layer 40 located between the first LED chip 220 and the first transfer plate 210, thereby separating the first LED chip 220 from the first transfer plate 210. The result is as follows. Figure 10 As shown.

[0091] In this embodiment, the first transfer plate 210 is a substrate made of semiconductor material. Since the bandgap of the sacrificial layer 40 is smaller than the bandgap of the substrate, when a laser with an energy between the bandgap of the sacrificial layer 40 and the bandgap of the substrate is used to irradiate the substrate from the side of the substrate away from the sacrificial layer 40, the laser passes through the substrate and is absorbed by the sacrificial layer 40, causing the sacrificial layer 40 to undergo thermal decomposition, thereby causing the first LED chip 220 to separate from the substrate.

[0092] The substrate may be made of semiconductor materials such as sapphire or silicon carbide, and the sacrificial layer 40 may be a gallium nitride layer or an ion-doped gallium nitride layer.

[0093] In this embodiment, the sacrificial layer 40 located within the orthogonal projection area of ​​the first LED chip 220 to be transferred on the first transfer plate 210 is selectively irradiated with a laser, thereby selectively peeling the first LED chip 220 to be transferred from the substrate. Furthermore, in this embodiment, the first LED chip 220 grown on the substrate is directly transferred to the display backplane 100. Compared to existing transfer technologies that require multiple transfers to a transient plate when transferring an LED chip from the substrate to the display backplane, the transfer method provided in this embodiment reduces the number of transfers and improves transfer efficiency and yield.

[0094] In some other embodiments, the sacrificial layer 40 between the first LED chip 220 and the first transfer plate 210 is an adhesive layer. Step S105, which involves peeling the first LED chip 220 to be transferred from the first transfer plate 210, includes: irradiating the first transfer plate 210 with a laser from the side of the first transfer plate 210 away from the first LED chip 220 to be transferred. The area of ​​the first transfer plate 210 irradiated by the laser coincides with the orthographic projection of the first LED chip 220 onto the first transfer plate 210. The adhesive layer between the first LED chip 220 to be transferred and the first transfer plate 210 becomes less viscous under laser irradiation, allowing the first LED chip 220 to be separated from the first transfer plate 210. The adhesive layer may be a photodegradable adhesive layer. The first transfer plate 210 may be a glass plate.

[0095] In this embodiment, by selectively irradiating the adhesive layer located in the orthographic projection area of ​​the first LED chip 220 to be transferred on the first transfer plate 210 with a laser, the viscosity of the adhesive layer between the first LED chip 220 to be transferred and the first transfer plate 210 is selectively reduced, thereby selectively peeling the first LED chip 220 to be transferred from the first transfer plate 210.

[0096] Please refer to the following: Figures 11 to 14 , Figure 11 A flowchart of an LED chip transfer method provided in another embodiment of this application. Figure 12 This is a cross-sectional schematic diagram of the second transfer plate 310 provided in an embodiment of this application. Figure 13 for Figure 11 A schematic diagram showing the positional relationship between the second transfer plate 310 and the display back plate 100 after step S107 is completed. Figure 14 for Figure 11 A schematic diagram showing the positional relationship between the second LED chip 320 and the display backplate 100 after step S109 is completed. Figure 13 As shown, in some embodiments, the pad group 130 further includes at least one second sub-pad group 132. For example... Figure 11 As shown, after the first electrode group 221 is bonded to the corresponding first sub-pad group 131, the LED chip transfer method further includes the following steps:

[0097] S106: Provide as follows Figure 12The second transfer plate 310 shown carries at least one second LED chip 320. The second electrode group 321 of the second LED chip 320 is covered with a second magnetic conductive layer 330. The light emission color of the second LED chip 320 is different from that of the first LED chip 220.

[0098] S107: The second LED chip 320 is at least partially embedded in the adhesion layer 140, wherein the second LED chip 320 to be transferred is aligned with the corresponding second sub-pad group 132, as shown in the figure. Figure 13 As shown.

[0099] S108: Apply an electrical signal to each of the second sub-pad groups 132 to generate a magnetic field located on the second side of the substrate 120.

[0100] S109: The second LED chip 320 to be transferred is peeled off from the second transfer plate 310. Under the magnetic force perpendicular to the substrate 120, the second magnetic conductive layer 330 drives the second LED chip 320 to move towards the corresponding second sub-pad group 132 until the second electrode group 321 is attached to the corresponding second sub-pad group 132, as shown in the figure. Figure 14 As shown.

[0101] In the LED chip transfer method provided in this application embodiment, since the first LED chip 220 is fixed to the side of the first sub-pad group 131 of the display backplate 100 away from the substrate 120 under the action of magnetic adsorption and adhesion, the process of transferring the second LED chip 320 to the display backplate 100 is not affected, thus avoiding the problem of mutual interference when transferring LED chips of different emitting colors separately.

[0102] In some embodiments, such as Figure 12 As shown, the second LED chip 320 also includes a second epitaxial structure 322, which is stacked on the second transfer plate 310 in sequence with the second electrode group 321.

[0103] Steps S108 and S109 can be performed simultaneously, that is, while applying an electrical signal to the second sub-pad group 132, the second LED chip 320 to be transferred is peeled off from the second transfer plate 310. Alternatively, step S108 can precede step S109, that is, a magnetic field located on the second side of the substrate 120 is generated first, and then the second LED chip 320 to be transferred is peeled off from the first transfer plate 310.

[0104] The method for peeling the second LED chip 320 to be transferred from the second transfer plate 310 can be referred to the aforementioned method for peeling the first LED chip 220 from the first transfer plate 210, and will not be repeated here.

[0105] In some embodiments, the second electrode group 321 also includes a positive electrode and a negative electrode, and the second sub-pad group 132 also includes a positive electrode pad and a negative electrode pad. When the second electrode group 321 is bonded to the corresponding second sub-pad group 132, the positive electrode of the second electrode group 321 is bonded to the positive electrode pad of the corresponding second sub-pad group 132, and the negative electrode of the second electrode group 321 is bonded to the negative electrode pad of the second sub-pad group 132. The materials of the positive electrode of the second electrode group 321, the negative electrode of the second electrode group 321, the positive electrode pad of the second sub-pad group 132, and the negative electrode pad of the second sub-pad group 132 can all be metallic materials, such as gold, indium, tin, copper, nickel, etc.

[0106] Specifically, when applying electrical signals to each of the second sub-pad groups 132 to generate a magnetic field on the second side of the substrate 120, the TFT layer is also used to selectively control the connection between the second sub-pad group 132 in the pad group 130 and the positive lead 150 and the negative lead 160 when the second LED chip 320 is transferred to the display backplane 100. This ensures that only the positive pad and the negative pad of the second sub-pad group 132 in the pad group 130 generate an electric field, which in turn generates a magnetic field. This avoids the magnetic field direction generated by other pad groups in the pad group 130 besides the second sub-pad group 132 from affecting the magnetic field direction generated by the second sub-pad group 132.

[0107] Please refer to the following: Figures 15 to 18 , Figure 15 A flowchart illustrating an LED chip transfer method provided in another embodiment of this application. Figure 16 This is a cross-sectional schematic diagram of the third transfer plate 410 provided in an embodiment of this application. Figure 17 for Figure 15 A schematic diagram showing the positional relationship between the third transfer plate 410 and the display back plate 100 after step S110 is completed. Figure 18 for Figure 15 A schematic diagram showing the positional relationship between the third LED chip 420 and the display backplate 100 after step S112 is completed. Figure 17 As shown, in some embodiments, the pad group 130 further includes at least one third sub-pad group 133. For example... Figure 15As shown, after the second electrode group 321 is attached to the corresponding second sub-pad group 132, the LED chip transfer method further includes the following steps:

[0108] S110: Provides, for example Figure 16 The third transfer plate 410 shown carries at least one third LED chip 420. The third electrode group 421 of the third LED chip 420 is covered with a third magnetic conductive layer 430. The light emission color of the third LED chip 420 is different from the light emission colors of the first LED chip 220 and the second LED chip 320.

[0109] S111: The third LED chip 420 is at least partially embedded in the adhesion layer 140, wherein the third LED chip 420 to be transferred is aligned with the corresponding third sub-pad group 133, as shown in the figure. Figure 17 As shown.

[0110] S112: Apply an electrical signal to each of the third sub-pad groups 133 to generate a magnetic field located on the second side of the substrate 120.

[0111] S113: The third LED chip 420 to be transferred is peeled off from the third transfer plate 410. Under the magnetic force perpendicular to the substrate 120, the third magnetic conductive layer 430 drives the third LED chip 420 to move towards the corresponding third sub-pad group 133 until the third electrode group 421 is attached to the corresponding third sub-pad group 133, as shown in the figure. Figure 18 As shown.

[0112] Steps S112 and S113 can be performed simultaneously, that is, while applying an electrical signal to the third sub-pad group 133, the third LED chip 420 to be transferred is peeled off from the third transfer plate 410. Alternatively, step S112 can precede step S113, that is, a magnetic field located on the second side of the substrate 120 is generated first, and then the third LED chip 420 to be transferred is peeled off from the second transfer plate 410.

[0113] In some embodiments, such as Figure 16 As shown, the third LED chip 420 also includes a third epitaxial structure 422, which is stacked sequentially with the third electrode group 421 on the third transfer plate 410.

[0114] The method for peeling the third LED chip 420 to be transferred from the third transfer plate 410 can be referred to the aforementioned method for peeling the first LED chip 220 from the first transfer plate 210, and will not be repeated here.

[0115] In some embodiments, the third electrode group 421 also includes a positive electrode and a negative electrode, and the third sub-pad group 133 also includes a positive pad and a negative pad. When the third electrode group 421 is attached to the corresponding third sub-pad group 133, the positive electrode of the third electrode group 421 is attached to the positive pad of the third sub-pad group 133, and the negative electrode of the third electrode group 421 is attached to the negative pad of the third sub-pad group 133. The materials of the positive electrode of the third electrode group 421, the negative electrode of the third electrode group 421, the positive pad of the third sub-pad group 133, and the negative pad of the third sub-pad group 133 can all be metallic materials, such as gold, indium, tin, copper, nickel, etc.

[0116] Specifically, when applying electrical signals to each of the third sub-pad groups 133 to generate a magnetic field located on the second side of the substrate 120, the TFT layer is also used to selectively control the connection between the third sub-pad group 133 in the pad group 130 and the positive lead 150 and the negative lead 160 when the third LED chip 420 is transferred to the display back panel 100. This ensures that only the positive pad and the negative pad of the third sub-pad group 133 in the pad group 130 generate an electric field, which in turn generates a magnetic field. This avoids the magnetic field direction generated by other pad groups in the pad group 130 other than the third sub-pad group 133 from affecting the magnetic field direction generated by the third sub-pad group 133.

[0117] In some embodiments, after the first electrode group 221 is bonded to the corresponding first sub-pad group 131, the second electrode group 321 is bonded to the corresponding second sub-pad group 132, and the third electrode group 421 is bonded to the corresponding third sub-pad group 133, the LED chip transfer method further includes: bonding the first electrode group 221 and the first magnetic conductive layer 230 to the first sub-pad group 131, and simultaneously bonding the second electrode group 321 and the second magnetic conductive layer 330 to the second sub-pad group 132 and the third electrode group 421 and the third magnetic conductive layer 430 to the third sub-pad group 133.

[0118] Specifically, the first electrode group 221, the first magnetic conductive layer 230, the first sub-pad group 131, the second electrode group 321, the second magnetic conductive layer 330, the second sub-pad group bonding 132, the third electrode group 421, the third magnetic conductive layer 430, and the third sub-pad group 133 can be heated simultaneously, causing the first electrode group 221, the first magnetic conductive layer 230, and the first sub-pad group 131 to melt and fuse together; the second electrode group 321, the second magnetic conductive layer 330, and the second sub-pad group bonding 132 to fuse together; and the third electrode group 421 to melt and fuse together; and the third electrode group 421, the third magnetic conductive layer 430, and the third sub-pad group to fuse together. Group 133 is melted and fused together, and then cooled to form the first electrode group 221, the first magnetic conductive layer 230, the first sub-pad group 131, the second electrode group 321, the second magnetic conductive layer 330, the second sub-pad group bonding 132, the third electrode group 421, the third magnetic conductive layer 430, and the third sub-pad group 133. This results in the first electrode group 221, the first magnetic conductive layer 230, and the first sub-pad group 131 being bonded together; the second electrode group 321, the second magnetic conductive layer 330, and the second sub-pad group bonding 132 being bonded together; and the third electrode group 421, the third magnetic conductive layer 430, and the third sub-pad group 133 being bonded together.

[0119] In the LED chip transfer method provided in this application embodiment, since the electrode group of the LED chip is adsorbed onto the pad group of the display backplate 100, the electrode group of the three-color LED chip can be bonded to the pad group of the display backplate 100 simultaneously after the electrode group of the three-color LED chip is bonded to the pad group of the display backplate 100. Compared with the prior art, which requires the electrode group of a single-color LED chip to be bonded to the pad group of the display backplate before the transfer of another single-color LED chip, this method avoids damage to the LED chip caused by multiple bonding, and avoids oxidation or damage to the bonding material caused by multiple bonding, which would result in poor bonding between the electrode group and the pad group.

[0120] This application embodiment also provides a display panel. The display panel includes the aforementioned display backplate 100 and at least one LED chip fixed on the display backplate 100, wherein the at least one LED chip is fixed on the display backplate 100 using the aforementioned LED chip transfer method.

[0121] The display panel provided in this application uses the aforementioned LED chip transfer method to transfer LED chips. By utilizing the magnetic attraction of the display backplate 100 to the at least one LED chip and the adhesive force of the adhesive layer 140 to the at least one LED chip, the at least one LED chip will not shift under the combined action of magnetic force and adhesive force when it is peeled off from the transfer plate. This allows for precise alignment and bonding with the corresponding position of the display backplate 100, improving transfer efficiency and yield, and reducing the manufacturing cost of the display panel.

[0122] It should be noted that, for the sake of simplicity, the aforementioned method embodiments are described as a series of actions. However, those skilled in the art should understand that this application is not limited to the described order of actions, because according to this application, some steps may be performed in other orders or simultaneously.

[0123] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0124] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for transferring an LED chip, characterized in that, include: A display backplane is provided, the display backplane including a magnetic shielding layer, a substrate, at least one pad group and an adhesive layer, the magnetic shielding layer being disposed on a first side of the substrate, the pad group being disposed on a second side of the substrate, the pad group including at least one first sub-pad group, the first side and the second side of the substrate being disposed opposite to each other, and the adhesive layer being disposed on the second side of the substrate and covering the pad group. A first transfer plate is provided, on which at least one first LED chip is carried, and a first magnetic conductive layer is covered on the first electrode group of the first LED chip. The first LED chip is at least partially embedded in the adhesive layer, wherein the first LED chip to be transferred is aligned with the corresponding first sub-pad group; Apply electrical signals to each of the first sub-pad groups to generate a magnetic field located on the second side of the substrate; and The first LED chip to be transferred is peeled off from the first transfer plate. Under the action of a magnetic force perpendicular to the substrate, the first magnetic conductive layer drives the first LED chip to move toward the corresponding first sub-pad group until the first electrode group is attached to the corresponding first sub-pad group.

2. The transfer method as described in claim 1, characterized in that, The first sub-pad group includes a positive pad and a negative pad. Applying an electrical signal to each of the first sub-pad groups to generate a magnetic field located on the second side of the substrate includes: A first electrical signal and a second electrical signal are applied to the positive electrode pad and the negative electrode pad respectively, so that a voltage difference is formed between the positive electrode pad and the negative electrode pad. The first electrical signal and the second electrical signal are controlled to make the voltage difference change periodically, so as to generate a magnetic field located on the second side of the substrate.

3. The transfer method as described in claim 2, characterized in that, The control of the first electrical signal and the second electrical signal to cause the voltage difference to change periodically includes: The first electrical signal and the second electrical signal are controlled to cause the voltage difference to periodically increase from a first voltage difference value to a second voltage difference value.

4. The transfer method as described in claim 1, characterized in that, After the first electrode group is bonded to the corresponding first sub-pad group, the method further includes: The first electrode group, the first magnetic conductive layer, and the first sub-pad group are bonded together.

5. The transfer method as described in claim 1, characterized in that, A sacrificial layer is disposed between the first LED chip and the first transfer plate. The step of peeling the first LED chip to be transferred from the first transfer plate includes: The sacrificial layer is selectively irradiated with a laser within the orthogonal projection area of ​​the first LED chip to be transferred on the first transfer plate.

6. The transfer method as described in claim 1, characterized in that, The pad group further includes at least one second sub-pad group, and after the first electrode group is bonded to the corresponding first sub-pad group, the method further includes: A second transfer plate is provided, on which at least one second LED chip is carried. The second electrode group of the second LED chip is covered with a second magnetic conductive layer. The emission color of the second LED chip is different from that of the first LED chip. The second LED chip is at least partially embedded in the adhesive layer, wherein the second LED chip to be transferred is aligned with the corresponding second sub-pad group; Apply electrical signals to each of the second sub-pad groups to generate a magnetic field located on the second side of the substrate; and The second LED chip to be transferred is peeled off from the second transfer plate. Under the action of a magnetic force perpendicular to the substrate, the second magnetic conductive layer drives the second LED chip to move toward the corresponding second sub-pad group until the second electrode group is attached to the corresponding second sub-pad group.

7. The transfer method as described in claim 6, characterized in that, The pad group further includes at least one third sub-pad group, and after the second electrode group is bonded to the corresponding second sub-pad group, the method further includes: A third transfer board is provided, on which at least one third LED chip is carried. The third electrode group of the third LED chip is covered with a third magnetic conductive layer. The emission color of the third LED chip is different from the emission color of the first LED chip and the second LED chip. The third LED chip is at least partially embedded in the adhesive layer, wherein the third LED chip to be transferred is aligned with the corresponding third sub-pad group; Apply electrical signals to each of the third sub-pad groups to generate a magnetic field located on the second side of the substrate; and The third LED chip to be transferred is peeled off from the third transfer plate. Under the action of a magnetic force perpendicular to the substrate, the third magnetic conductive layer drives the third LED chip to move toward the corresponding third sub-pad group until the third electrode group is attached to the corresponding third sub-pad group.

8. The transfer method as described in claim 7, characterized in that, The transfer method further includes: bonding the first electrode group, the first magnetic conductive layer and the first sub-pad group, and simultaneously bonding the second electrode group, the second magnetic conductive layer and the second sub-pad group, and bonding the third electrode group, the third magnetic conductive layer and the third sub-pad group.

9. The transfer method as described in claim 2, characterized in that, The first electrode group includes a positive electrode and a negative electrode. When the first electrode group is bonded to the corresponding first sub-pad group, the positive electrode is bonded to the positive pad and the negative electrode is bonded to the negative pad.

10. A display panel, characterized in that, The display panel includes a display backplate and at least one LED chip fixed to the display backplate, wherein the at least one LED chip is fixed to the display backplate using the LED chip transfer method as described in any one of claims 1-9.

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