Mass transfer method, LED display device and display apparatus

Abstract

This application relates to a mass transfer method, an LED display device, and a display apparatus. The mass transfer method involves applying an insulating adhesive to a growth substrate, creating an insulating adhesive layer between adjacent LED chips; placing the growth substrate above a display backplane, ensuring the distance between the growth substrate and the backplane is greater than the height of the LED chips; extending the softened insulating adhesive to bond with the display backplane, forming insulating adhesive pillars between the growth substrate and the backplane; separating the LED chips from the growth substrate, with the separated LED chips falling along the channels formed by the insulating adhesive pillars around them onto corresponding pad groups; and bonding the LED chips to corresponding pad groups on the display backplane. This simplifies the transfer process from the growth substrate to the display backplane, reduces material consumption, and lowers costs. The adhesive strength of the insulating adhesive ensures precise alignment of the LED chips, guarantees proper LED chip connection, and prevents LED chips from detaching.

Description

Technical Field

[0001] This application relates to the field of mass transfer technology, and more particularly to mass transfer methods, LED display devices, and display apparatuses. Background Technology

[0002] Currently, Micro LED (Micro Light-emitting Diode) display panels, as a new generation of display technology, have advantages such as higher brightness, better luminous efficiency, and lower power consumption, making Micro LED widely used.

[0003] Micro LED display panels typically consist of multiple pixel areas, each containing red, blue, and green LED chips. During panel fabrication, these three types of chips need to be transferred from their respective growth substrates to a display backplane. Current transfer methods require more materials, are more expensive, and are quite complex, involving multiple transfers of the LED chips. This can easily lead to misalignment between the LED chips and the pads on the display backplane, compromising solder strength and causing abnormal connections between the LED chips and the driving circuitry, or even detachment from the display backplane. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this application is to provide a mass transfer method, an LED display device and a display apparatus, which aims to solve the problem that the LED chip cannot be aligned with the pad group on the display back panel, making it difficult to guarantee the welding strength of the LED chip, resulting in abnormal connection between the LED chip and the driving circuit, or even detachment from the display back panel.

[0005] A first aspect of this application provides a mass transfer method, comprising: applying an insulating adhesive to a growth substrate such that the insulating adhesive is present between any two adjacent LED chips; placing the growth substrate above a display backplate such that the distance between the growth substrate and the display backplate is greater than the height of the LED chips; heating the insulating adhesive to soften it, wherein the softened insulating adhesive extends to adhere to the display backplate, thereby forming an insulating adhesive pillar between the growth substrate and the display backplate; separating the LED chips from the growth substrate, wherein the separated LED chips fall along the channels formed by the insulating adhesive pillars around them onto corresponding pad groups; and bonding the LED chips to the corresponding pad groups on the display backplate.

[0006] The aforementioned mass transfer method can directly transfer LED chips from the growth substrate to the display backplane, greatly simplifying the transfer process. Furthermore, only one type of adhesive, insulating material, is required during the transfer, resulting in lower material consumption and overall reduced costs. Additionally, the adhesive strength of the insulating material supports the growth substrate and display backplane, ensuring precise alignment of the LED chips and pads, guaranteeing the soldering strength of the LED chips, ensuring proper connection between the LED chips and the driving circuit, and preventing the LED chips from detaching from the display backplane.

[0007] In some embodiments, after the insulating adhesive is present between any two adjacent LED chips, a gap is also formed between the insulating adhesive and the two adjacent LED chips. This gap between the insulating adhesive and the two adjacent LED chips ensures that the insulating adhesive pillars subsequently formed by the insulating adhesive are also spaced between the two adjacent LED chips. This prevents the insulating adhesive pillars from adhering to the LED chips during subsequent LED chip peeling, thus avoiding affecting the light output brightness and light emission consistency of the LED chips.

[0008] In some embodiments, applying an insulating adhesive to the growth substrate such that there is an insulating adhesive between any two adjacent LED chips specifically includes: applying an insulating adhesive to the growth substrate such that there is an insulating adhesive with a cross-section that is narrow at both ends and wide in the middle between any two adjacent LED chips. This cross-section refers to the cross-section of the insulating adhesive along its thickness direction. This allows the insulating adhesive to have a shape that is narrow at both ends and wide in the middle, thereby ensuring that the insulating adhesive does not contact the LED chips, has sufficient adhesive strength, and has sufficient reserve.

[0009] In some embodiments, applying an insulating adhesive to the growth substrate such that there is an insulating adhesive between any two adjacent LED chips specifically includes: applying an insulating adhesive to the growth substrate such that there is an insulating adhesive with a circular or elliptical cross-section between any two adjacent LED chips. This cross-section refers to the cross-section of the insulating adhesive along its thickness direction. This allows the insulating adhesive to have a shape that is narrow at both ends and wide in the middle, thereby ensuring that the insulating adhesive does not contact the LED chips, has sufficient adhesive strength, and has sufficient reserve.

[0010] In some embodiments, forming an insulating adhesive pillar between the growth substrate and the display backplane specifically includes: forming an insulating adhesive pillar with a cross-section narrow at both ends and wide in the middle between the growth substrate and the display backplane. Specifically, the insulating adhesive pillar with an elliptical cross-section can be formed between the growth substrate and the display backplane. The aforementioned cross-section refers to the cross-section along the thickness direction of the insulating adhesive pillar.

[0011] Therefore, the narrower end of the insulating adhesive column, which adheres to the growth substrate, ensures adhesion while preventing contact between the column and the LED chip. The wider middle section provides sufficient amount of adhesive, providing adequate support for the growth substrate and display backplane, preventing changes in their relative positions. The narrower end of the insulating adhesive column, which adheres to the display backplane, also ensures adhesion while preventing contact between the column and the pad assembly.

[0012] In some embodiments, forming an insulating adhesive pillar between the growth substrate and the display backplane specifically includes forming an insulating adhesive pillar with an elliptical cross-section between the growth substrate and the display backplane. This ensures that the insulating adhesive pillar does not contact the LED chip and pad assembly, has sufficient adhesive force, and has sufficient quantity to support the growth substrate and the display backplane.

[0013] In some embodiments, after forming insulating adhesive pillars between the growth substrate and the display backplane, the insulating adhesive pillars are spaced apart from two adjacent LED chips. This prevents the insulating adhesive pillars from adhering to the LED chips during subsequent LED chip peeling, thus avoiding impact on the LED chip's brightness and luminous uniformity.

[0014] In some embodiments, applying an insulating adhesive to the growth substrate such that there is an insulating adhesive between any two adjacent LED chips specifically includes: applying an insulating adhesive to the growth substrate such that there is an insulating adhesive between any two adjacent LED chips, and such that the insulating adhesive is lower than or flush with the LED chips. This prevents the insulating adhesive from being too thick, thereby preventing the insulating adhesive from flowing between the LED chip and the pad assembly during soldering, which could lead to poor soldering strength; additionally, it can save raw materials and reduce costs.

[0015] In some embodiments, before applying insulating adhesive to the growth substrate, the mass transfer method further includes: forming a first groove between any two adjacent LED chips on the growth substrate; applying insulating adhesive to the growth substrate such that the insulating adhesive is present between any two adjacent LED chips. Specifically, this includes applying insulating adhesive to the growth substrate such that the insulating adhesive is present between any two adjacent LED chips, and such that at least a portion of the insulating adhesive is located within the first groove. Thus, after the insulating adhesive softens subsequently, the first groove can guide the flow of the insulating adhesive, preventing it from flowing into contact with the LED chips.

[0016] In some embodiments, before softening the insulating adhesive, the mass transfer method further includes: providing a second groove between adjacent pad groups on the display backplane; softening the insulating adhesive, wherein the softened insulating adhesive extends to adhere to the display backplane to form an insulating adhesive pillar between the growth substrate and the display backplane, specifically including: softening the insulating adhesive, wherein the softened insulating adhesive extends to adhere to the display backplane, and at least a portion of the insulating adhesive adhered to the display backplane extends into the second groove to form an insulating adhesive pillar between the growth substrate and the display backplane. Thus, after subsequent softening of the insulating adhesive, the second groove can guide the flow of the insulating adhesive, preventing the insulating adhesive from flowing into contact with the pad groups.

[0017] In some embodiments, the growth substrate is disposed above the display backplane, such that the distance between the growth substrate and the display backplane is greater than the height of the LED chip. Specifically, this includes: disposing the growth substrate above the display backplane such that the distance between the growth substrate and the display backplane is greater than or equal to 20 micrometers. This allows the softened insulating adhesive to flow and adhere well to the display backplane, while also ensuring sufficient adhesion between the insulating adhesive and the LED chip. This allows the LED chip to be supported in a position precisely aligned with the pad assembly, without excessive flow onto the display backplane, ensuring that the pad assembly is not affected by the insulating adhesive.

[0018] In some embodiments, before applying insulating adhesive to the growth substrate, the mass transfer method further includes: detecting defective LED chips on the growth substrate; separating the LED chips from the growth substrate specifically includes: separating at least a portion of the LED chips, excluding the defective LED chips, from the growth substrate. This ensures that the LED chips transferred to the display backplane are all LED chips with normal appearance and good wavelength consistency, resulting in better luminous uniformity in the final fabricated display device and improving the quality of the fabricated display device.

[0019] In some embodiments, after separating at least some of the LED chips (excluding the defective LED chips) from the growth substrate, the mass transfer method further includes: adding another LED chip to the pad group corresponding to the defective LED chip. This prevents gaps in the pad group corresponding to the defective LED chip, resulting in more complete pixels on the final fabricated display device, thereby improving the display effect.

[0020] A second aspect of this application provides an LED display device, including a display backplane and a plurality of LED chips, wherein the plurality of LED chips are transferred onto the display backplane using the mass transfer method described in any one of the first aspects of this application.

[0021] A third aspect of this application provides a display device, including a driving circuit and an LED display device as described in any one of the second aspects of this application, wherein the LED display device and the driving circuit are electrically connected. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a growth substrate provided by existing technology.

[0023] Figure 2 This is a schematic diagram of the growth substrate from another perspective provided by existing technology.

[0024] Figure 3 This is a schematic diagram of a temporary substrate bonded to a growth substrate using existing technology.

[0025] Figure 4 This is a schematic diagram of the process structure for transferring LED chips onto a temporary substrate provided by existing technology.

[0026] Figure 5 This is a schematic diagram of a temporary substrate with LED chips transferred using existing technology.

[0027] Figure 6 This is a schematic diagram of the structure of a temporary substrate with an LED chip transferred, provided by existing technology, from another perspective.

[0028] Figure 7 This is a schematic diagram of the structure provided by the existing technology for transferring LED chips to the display backplane using a transfer substrate.

[0029] Figure 8 This is a schematic diagram of a display backplane with LED chips provided by existing technology.

[0030] Figure 9 This is a flowchart of a mass transfer method provided in one embodiment of this application.

[0031] Figures 10 to 13 This is a schematic diagram of the process flow of a mass transfer method provided in one embodiment of this application.

[0032] Figure 14 yes Figure 13 The diagram shows a detailed process flow.

[0033] Figure 15 This is a flowchart of a mass transfer method provided in another embodiment of this application.

[0034] Figures 16 to 20 This is a schematic diagram of the process flow of a mass transfer method provided in another embodiment of this application.

[0035] Figure 21This is a flowchart of a mass transfer method provided in another embodiment of this application.

[0036] Figure 22 yes Figure 21 The process flow diagram for step S350 shown is illustrated.

[0037] Figure 23 This is a schematic diagram of the properties of the insulating adhesive provided in the embodiments of this application.

[0038] Figure 24 This is a schematic diagram of the structure in which a first groove is provided on the growth substrate in an embodiment of this application.

[0039] Figure 25 This is a schematic diagram of the structure of the second groove provided on the display back plate in an embodiment of this application.

[0040] Figure 26 This is a schematic diagram of the structure of the LED display device provided in the embodiments of this application.

[0041] Explanation of reference numerals in the attached drawings: 10-Growth substrate, 11-First groove, 20-LED chip, 20a-Defective LED chip, 30-Temporary substrate, 40-Transfer substrate, 50-Display backplate, 51-Pad group, 52-Second groove, 60-Insulating adhesive, 61-First bottom edge, 62-Second bottom edge, 70-Insulating adhesive column, 71-Third bottom edge, 72-Fourth bottom edge, 80-Repair adhesive plate. Detailed Implementation

[0042] 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.

[0043] 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.

[0044] For details, please refer to [link / reference]. Figures 1 to 6 ,visible, Figure 1 This is a schematic diagram of the growth substrate provided in the embodiments of this application;

[0045] Figure 2 This is a schematic diagram of the growth substrate provided in an embodiment of this application from another perspective; Figure 3 This is a schematic diagram of the structure of the temporary substrate bonded to the growth substrate according to an embodiment of this application; Figure 4This is a schematic diagram of the process structure for transferring LED chips onto a temporary substrate provided in an embodiment of this application; Figure 5 This is a schematic diagram of the temporary substrate with LED chips transferred according to an embodiment of this application; Figure 6 This is a schematic diagram of the temporary substrate with LED chips transferred from another perspective, provided in an embodiment of this application.

[0046] Generally, when the LED chip 20 is transferred to the display back panel 50, the red LED chip, blue LED chip and green LED chip are transferred respectively. The following explanation uses one type of LED chip 20 as an example. The other two types of LED chips are handled in the same way and will not be repeated in this application.

[0047] The LED chip 20 is transferred to the display back panel 50. The specific process is as follows.

[0048] Step S10: A growth substrate 10 is provided, on which an LED chip 20 is grown. Then, using an adhesive layer on a temporary substrate 30, the LED chip 20 is bonded to the temporary substrate 30. Next, the growth substrate 10 is peeled off from the LED chip 20. Thus, the LED chip 20 can be transferred to the temporary substrate 30.

[0049] Step S11: Using the adhesive layer on the transfer substrate 40, selectively bond the LED chip 20 to the transfer substrate 40; Reference Figure 7 , Figure 7 The display transfer substrate 40 selectively bonds LED chips 20 onto the temporary substrate 30.

[0050] Step S12: Transfer the LED chip 20 on the transfer substrate 40 to the display backplane 50. (Reference) Figure 8 , Figure 8 The diagram shows a successful transfer of the LED chip 20 onto the display backplane 50. The process of transferring the LED chip 20 from the transfer substrate 40 to the display backplane 50 is also a mass soldering process. Therefore, after the transfer is completed, the LED chip 20 has completed gold-indium eutectic bonding.

[0051] In the aforementioned mass transfer process, the adhesion of the adhesive layer on the temporary substrate must be less than that on the transfer substrate. This results in a high cost due to the large amount of consumables required. Furthermore, the entire process involves multiple transfers of LED chips from the growth substrate to the temporary substrate, then to the transfer substrate, and finally to the display backplane. This cumbersome process, involving multiple transfers, can easily lead to misalignment of the LED chips with the pads on the display backplane. This compromises the soldering strength of the LED chips, causing abnormal connections between the LED chips and the driving circuitry, and even detachment from the display backplane.

[0052] To address the aforementioned problems, this application provides a mass transfer method in one embodiment. Please refer to [link / reference needed]. Figures 9 to 13 , Figure 9 This is a flowchart of a mass transfer method provided in one embodiment of this application. Figures 10 to 13 This is a schematic diagram of the process flow of a mass transfer method provided in one embodiment of this application. The mass transfer method includes the following steps:

[0053] refer to Figure 10 S100: Apply insulating adhesive 60 to the growth substrate 10, ensuring that the insulating adhesive 60 is present between any two adjacent LED chips 20. This insulating adhesive 60 is a non-conductive adhesive (NCF). The viscosity of NCF changes significantly with temperature variations.

[0054] It should be understood that the LED chips 20 are generally arranged in an array on the growth substrate 10, and there is a gap between any two adjacent LED chips 20, with multiple gaps forming a channel. Those skilled in the art also need to understand that, in order to ensure a gap between the insulating adhesive 60 and the bonded LED chips 20, the insulating adhesive 60 cannot fill the entire channel, thereby preventing the LED chips 20 from contacting the insulating adhesive 60. This prevents the insulating adhesive pillars 70 formed by the insulating adhesive 60 from adhering to the LED chips 20 when they are subsequently peeled off from the growth substrate 10, thus avoiding the adhesive affecting the light output brightness and light emission uniformity of the LED chips 20.

[0055] In some embodiments, applying an insulating adhesive 60 to the growth substrate 10 may specifically include applying an insulating adhesive 60 with a cross-section that is narrow at both ends and wide in the middle along its thickness direction to the growth substrate 10.

[0056] Specifically, the insulating adhesive 60 has a first cross-section along its thickness direction, the first cross-section having a first bottom edge 61 in contact with the growth substrate 10 and a second bottom edge 62 away from the growth substrate 10. The width of the insulating adhesive 60 gradually increases from the first bottom edge 61 to its middle portion, and the width gradually increases from the second bottom edge 62 to its middle portion.

[0057] This means that the width of the first cross-section of the insulating adhesive 60 gradually increases from both ends to the middle in its thickness direction. Since the insulating adhesive 60 easily comes into contact with the LED chip 20 at the first bottom edge 61 and the second bottom edge 62, the first bottom edge 61 and the second bottom edge 62 are made relatively narrow. This ensures that the insulating adhesive 60 can adhere to the growth substrate 10 while preventing it from contacting the LED chip 20. The width gradually increases at the remaining positions between the first bottom edge 61 and the second bottom edge 62, allowing for a sufficient amount of insulating adhesive 60 to flow and adhere to the display backplate 50 after softening.

[0058] In detail, in some specific embodiments, applying an insulating adhesive 60 to the growth substrate 10 so that any two adjacent LED chips 20 are provided with the insulating adhesive 60 specifically includes: applying an insulating adhesive 60 to the growth substrate 10 so that any two adjacent LED chips 20 are provided with the insulating adhesive 60 having a circular or elliptical cross-section.

[0059] That is, the first cross-section can be circular. However, it should be understood that because the insulating adhesive 60 has a certain degree of adhesion, its contact point with the growth substrate 10 will deform. In other words, the contact point between the circular first cross-section and the growth substrate 10 will be a straight line, not a perfect circle. A circular first cross-section allows it to be narrow at both ends and wide in the middle, thus ensuring that the insulating adhesive 60 does not contact the LED chip 20, has sufficient adhesive force, and has sufficient reserve.

[0060] In other specific embodiments, the first cross-section is elliptical, and the major axis of the ellipse containing the first cross-section is parallel to the thickness direction of the insulating adhesive 60. Of course, its contact point with the growth substrate 10 is also linear. The elliptical shape of the first cross-section allows it to be narrow at both ends and wide in the middle, thereby ensuring that the insulating adhesive 60 does not contact the LED chip 20, has sufficient adhesive force, and has sufficient reserve for subsequent bonding of the display backplate 50.

[0061] Of course, in some other specific embodiments, the first cross section can also be an isosceles trapezoid with two bottom edges joined together, one of which has its top edge in contact with the growth substrate 10. This shape can also make the first cross section narrow at both ends and wide in the middle, thereby ensuring that the insulating adhesive 60 does not contact the LED chip 20, has sufficient adhesive force, and has sufficient reserve for subsequent bonding of the display backplate 50.

[0062] In some specific embodiments, applying an insulating adhesive 60 to the growth substrate 10 such that the insulating adhesive 60 is present between any two adjacent LED chips 20 specifically includes: applying the insulating adhesive 60 to the growth substrate 10 such that the insulating adhesive 60 is present between any two adjacent LED chips 20, and such that the insulating adhesive 60 is lower than or flush with the LED chip 20. Specifically, the insulating adhesive 60 has a first surface facing away from the growth substrate 10 and a second surface connected to the growth substrate 10. The first surface can be processed to be flush with the surface of the LED chip 20 facing away from the growth substrate 10; or the first surface can be processed to be lower than the surface of the LED chip 20 facing away from the growth substrate 10. This prevents the insulating adhesive 60 from being too thick, thus preventing the insulating adhesive 60 from flowing between the LED chip 20 and the pad group 51 during soldering, which would lead to poor soldering strength; additionally, it can save raw materials and reduce costs.

[0063] For example, before applying the insulating adhesive 60 to the growth substrate 10, the mass transfer method further includes: forming a first groove 11 between any two adjacent LED chips 20 on the growth substrate 10. Then, applying the insulating adhesive 60 to the growth substrate 10 such that the insulating adhesive 60 is present between any two adjacent LED chips 20 specifically includes: applying the insulating adhesive 60 to the growth substrate 10 such that the insulating adhesive 60 is present between any two adjacent LED chips 20, and such that at least a portion of the insulating adhesive 60 is located within the first groove 11. (See reference...) Figure 24 That is, a first groove 11 can be provided in the channel, and when the insulating adhesive 60 is filled in the channel, at least part of it is located in the first groove 11. Thus, after the insulating adhesive 60 softens, the first groove 11 can guide the flow of the insulating adhesive 60 and prevent the insulating adhesive 60 from flowing to contact the LED chip 20.

[0064] S110: Reference Figure 11The growth substrate 10 is positioned above the display backplate 50, such that the distance between the growth substrate 10 and the display backplate 50 is greater than the height of the LED chip 20. The display backplate 50 can specifically be a thin-film transistor (TFT) substrate, a printed circuit board (PCB), etc., and is not limited in this application. That is, the growth substrate 10 and the display backplate 50 are positioned above the display backplate 50 at intervals. Since the LED chips 20 ultimately need to be soldered to the pad groups 51 on the display backplate 50, it is necessary to ensure that multiple LED chips 20 correspond one-to-one with multiple pad groups 51 on the display backplate 50.

[0065] It is understood that the distance between the growth substrate 10 and the display back plate 50 specifically refers to the distance between the surface of the growth substrate 10 facing the display back plate 50 and the surface of the display back plate 50 facing the growth substrate 10.

[0066] The display backplate 50 is generally equipped with a driving circuit, which can drive the LED chip 20 to emit light smoothly, thereby ensuring that the relevant display devices can be used normally. The pad group 51 on the display backplate 50 can be formed by applying solder paste or other solder in dots onto the display backplate 50.

[0067] For example, the growth substrate 10 is positioned above the display backplate 50 such that the distance between the growth substrate 10 and the display backplate 50 is greater than the height of the LED chip 20. Specifically, this includes positioning the growth substrate 10 above the display backplate 50 such that the distance between the growth substrate 10 and the display backplate 50 is greater than or equal to 20 micrometers. If the growth substrate 10 and the display backplate 50 are too close, excessive amounts of the insulating adhesive 60 may flow onto the display backplate 50 after subsequent softening, thus covering the pad assembly 51 and preventing proper soldering between the pad assembly 51 and the LED chip 20. If the growth substrate 10 and the display backplate 50 are too far apart, the insulating adhesive 60 may be stretched excessively between the display backplate 50 and the growth substrate 10 when flowing onto the display backplate 50, affecting the adhesion of the insulating adhesive 60 to the LED chip 20 and potentially causing the insulating adhesive 60 to tilt, thereby affecting the alignment accuracy of the LED chip 20.

[0068] Setting the above distance allows the insulating adhesive 60 to soften and flow to adhere well to the display backplate 50, while also ensuring that the insulating adhesive 60 has sufficient adhesive force to the LED chip 20. This allows the LED chip 20 to be supported in a position precisely aligned with the pad assembly 51, without excessive flow onto the display backplate 50, thus ensuring that the pad assembly 51 is not affected by the insulating adhesive 60.

[0069] More specifically, when the growth substrate 10 is placed above the display back plate 50, the distance between the growth substrate 10 and the display back plate 50 needs to be less than or equal to 70 micrometers. This can prevent the distance between the display back plate 50 and the growth substrate 10 from being too far, which would result in a weak adhesion of the insulating adhesive 60 to the display back plate 50.

[0070] S120: Reference Figure 12 The insulating adhesive material 60 is heated to soften it, and the softened insulating adhesive material 60 extends to bond with the display back panel 50, thereby forming an insulating adhesive pillar 70 between the growth substrate 10 and the display back panel 50. Specifically, laser heating can be used to soften the insulating adhesive pillar 70.

[0071] Specifically, an insulating adhesive pillar 70 can be formed between the growth substrate 10 and the display backplate 50, with a gap between the insulating adhesive pillar 70 and two adjacent LED chips 20. This prevents the insulating adhesive pillar 70 from sticking to the LED chip 20 during subsequent peeling, thus avoiding the adhesive material affecting the light output brightness and light emission consistency of the LED chip.

[0072] refer to Figure 23 Curve L1 represents the temperature change curve, and curve L2 represents the viscosity change curve of insulating adhesive 60. It can be seen that as the temperature T rises from approximately 20 degrees Celsius (°C) to around 120°C, the viscosity of insulating adhesive 60 continuously decreases; between 120°C and 180°C, its viscosity remains essentially constant; and between 180°C and 200°C, the viscosity begins to increase again.

[0073] Therefore, the heating temperature can be controlled between 120°C and 140°C, which is lower than the melting point of the solder used to prepare the pad assembly 51, thus preventing the solder from melting. Furthermore, within this temperature range, the insulating adhesive column 70 has good fluidity, ensuring that a portion of the insulating adhesive 60 flows onto the display backplate 50 and adheres to it, while another portion remains bonded to the growth substrate 10. A further portion remains between the display backplate 50 and the growth substrate 10, resulting in a temporary connection between them, thus maintaining a relatively fixed position.

[0074] When heating stops and the temperature begins to drop, the viscosity of the insulating adhesive 60 will increase as the temperature decreases. At this time, the insulating adhesive 60 cools down, thus better bonding the growth substrate 10 and the display backplate 50. The growth substrate 10 and the display backplate 50 can be bonded and supported by the insulating adhesive pillars 70, so that the positions of the growth substrate 10 and the display backplate 50 are relatively fixed, thereby enabling the LED chip 20 to accurately correspond to the position of the pad group 51 and improving the alignment accuracy of the LED chip 20.

[0075] For example, before softening the insulating adhesive 60, the mass transfer method further includes: providing a second groove 52 between adjacent pad groups 51 on the display backplate 50. Then, softening the insulating adhesive 60, with the softened insulating adhesive 60 extending to bond with the display backplate 50 to form an insulating adhesive pillar 70 between the growth substrate 10 and the display backplate 50, specifically includes: softening the insulating adhesive 60, with the softened insulating adhesive 60 extending to bond with the display backplate 50, and at least a portion of the insulating adhesive 60 bonded to the display backplate 50 extending into the second groove 52 to form an insulating adhesive pillar 70 between the growth substrate 10 and the display backplate 50. (Reference) Figure 25 Specifically, a second groove 52 is provided between adjacent pad groups 51 on the display backplate 50, so that when the softened insulating adhesive 60 flows to adhere to the display backplate 50, at least a portion of the softened insulating adhesive 60 flows into the second groove 52. Therefore, after the insulating adhesive column 70 softens subsequently, the second groove 52 can guide the flow of the insulating adhesive column 70, preventing it from flowing into contact with the pad group 51.

[0076] For example, forming an insulating adhesive pillar 70 between the growth substrate 10 and the display backplate 50 specifically includes forming an insulating adhesive pillar 70 with a cross-section that is narrow at both ends and wide in the middle between the growth substrate 10 and the display backplate 50. Thus, the narrower end of the insulating adhesive pillar 70, which adheres to the growth substrate 10, ensures adhesion while preventing contact between the insulating adhesive pillar 70 and the LED chip 20. The wider middle portion of the insulating adhesive pillar 70 provides sufficient quantity to provide adequate support for the growth substrate 10 and the display backplate 50, preventing changes in their relative positions. The narrower end of the insulating adhesive pillar 70, which adheres to the display backplate 50, ensures adhesion while preventing contact between the insulating adhesive pillar 70 and the pad assembly 51.

[0077] In detail, the insulating adhesive column 70 has a second cross section along its thickness direction, the second cross section having a third bottom edge 71 that contacts the growth substrate 10 and a fourth bottom edge 72 that contacts the display back panel 50; the width of the insulating adhesive column 70 gradually increases from the third bottom edge 71 to its middle portion, and the width gradually increases from the fourth bottom edge 72 to its middle portion.

[0078] That is, the width of the second cross-section of the insulating adhesive column 70 gradually increases from both ends to the middle in its thickness direction. Since the insulating adhesive column 70 easily contacts the LED chip 20 at the third bottom edge 71 and the pad group 51 at the fourth bottom edge 72, the third bottom edge 71 is made relatively narrow. This ensures that the insulating adhesive column 70 adheres to the growth substrate 10 while preventing it from contacting the LED chip 20. Similarly, making the fourth bottom edge 72 relatively narrow ensures that the insulating adhesive column 70 adheres to the display backplate 50 while preventing it from contacting the pad group 51. The gradually increasing width at the remaining positions between the third and fourth bottom edges 71 provides sufficient quantity of insulating adhesive column 70, thus providing sufficient support for the growth substrate 10 and the display backplate 50 and preventing changes in their relative positions.

[0079] In some specific embodiments, the second cross-section is elliptical, and the major axis of the ellipse containing the second cross-section is parallel to the thickness direction of the insulating adhesive column 70. Naturally, its contact point with the growth substrate 10 is also linear. The elliptical shape of the second cross-section allows it to be narrow at both ends and wide in the middle, thereby ensuring that the insulating adhesive column 70 does not contact the LED chip 20 and the pad assembly 51, has sufficient adhesive force, and has enough quantity to support the growth substrate 10 and the display backplate 50.

[0080] Of course, in other specific embodiments, the second cross section can also be an isosceles trapezoid with two bottom edges joined together, one of which has its top edge in contact with the growth substrate 10. This shape can also make the second cross section narrow at both ends and wide in the middle, thereby ensuring that the insulating adhesive column 70 does not contact the LED chip 20 and the pad assembly 51, has sufficient adhesive force, and has sufficient amount to support the growth substrate 10 and the display backplate 50.

[0081] S130: Reference Figure 13The LED chip 20 is separated from the growth substrate 10 using a laser lift-off method. The separated LED chip 20 then falls along the channel formed by the insulating adhesive pillars 70 surrounding it onto the corresponding pad group 51. Because the insulating adhesive pillars 70 connect the growth substrate 10 and the display backplate 50, their relative positions are fixed, ensuring precise alignment between the LED chip 20 and the pad group 51. Therefore, when the LED chip 20 falls, it can accurately land on the corresponding pad group 51, thereby increasing the positional accuracy of the LED chip 20 and enabling better soldering.

[0082] The specific processes for separating the LED chip 20 from the growth substrate 10 and the insulating adhesive pillar 70 from the display backplate 50 are as follows: (Refer to...) Figure 14 , Figure 14 yes Figure 13 The schematic diagram of the process flow shown illustrates that, specifically, a laser is used to selectively peel the LED chip 20 from the growth substrate 10. A mask can be used to shield areas where laser irradiation is not required, preventing the laser from striking the insulating adhesive pillars 70. After the LED chip 20 is separated from the growth substrate 10, the growth substrate 10 is also separated. Specifically, the growth substrate 10 can be moved to another location using tools.

[0083] Because the display backplate 50 is made of metal, and the insulating adhesive pillars 70 have poor wettability with metal, the adhesive force of the insulating adhesive pillars 70 to the display backplate 50 is less than that to the growth substrate 10. Therefore, when the growth substrate 10 is removed using tools, the insulating adhesive pillars 70 are carried away by the growth substrate 10, thus separating the insulating adhesive pillars 70 from the display backplate 50. This prevents the insulating adhesive pillars 70 from remaining on the display backplate 50 and affecting the display of the LED chip 20, and also avoids the insulating adhesive pillars 70 causing poor heat dissipation in the final LED display device.

[0084] Step S140: The LED chip 20 is bonded to the corresponding pad group 51 on the display backplate 50. Bonding can be performed using a heating and pressurizing method. In step S130, the LED chip 20 is accurately lowered to contact the pad group 51, ensuring precise alignment during bonding and improving positioning accuracy.

[0085] It should be understood that the above process only takes one type of LED chip 20 as an example. For example, the LED chip 20 can be a red LED, and other colors, such as green LEDs and blue LEDs, can be transferred in the same way. This embodiment will not be described in detail.

[0086] As can be seen from the above, the mass transfer method provided in this embodiment can directly transfer the LED chip 20 from the growth substrate 10 to the display backplate 50, greatly simplifying the transfer process. Furthermore, only one type of adhesive, the insulating adhesive 60, is required during the transfer, resulting in less material consumption and reduced overall cost. In addition, the adhesive force of the insulating adhesive 60 supports the growth substrate 10 and the display backplate 50, ensuring precise alignment between the LED chip 20 and the pad assembly 51. This guarantees the welding strength of the LED chip 20, ensures proper connection between the LED chip 20 and the driving circuit, and prevents the LED chip 20 from detaching from the display backplate 50.

[0087] Another embodiment of this application provides a mass transfer method, which can be found in the following reference: Figures 15 to 20 , Figure 15 This is a flowchart of a mass transfer method provided in another embodiment of this application. Figures 16 to 20 This is a schematic diagram of the process flow for a mass transfer method according to another embodiment of this application. The mass transfer method provided in this embodiment specifically includes the following steps:

[0088] S200: Reference Figure 16 The defective LED chips 20a on the growth substrate 10 are detected. Specifically, micro-automated optical inspection (AOI) or micro-photoluminescence (PL) detection equipment can be used to detect the optical characteristics and appearance quality of the LED chips 20a on the growth substrate 10 in advance, generating corresponding mapping data. This allows the identification of defective LED chips 20a on the growth substrate 10. Therefore, when transferring the LEDs to the display backplane 50, defective LED chips 20a can be avoided, ensuring that the LED chips 20a transferred to the display backplane 50 have a better appearance and better wavelength consistency.

[0089] S210: Reference Figure 17 An insulating adhesive 60 is applied to the growth substrate 10, ensuring that the insulating adhesive 60 is present between any two adjacent LED chips 20. This step is the same as step S100 in the above embodiment and will not be described again.

[0090] S220: Reference Figure 18 The growth substrate 10 is positioned above the display backplate 50, such that the distance between the growth substrate 10 and the display backplate 50 is greater than the height of the LED chip 20. This step is the same as step S110 in the above embodiment and will not be described again.

[0091] S230: Reference Figure 19The insulating adhesive material 60 is heated to soften it, and the softened insulating adhesive material 60 extends to bond with the display back panel 50 to form an insulating adhesive pillar 70 between the growth substrate 10 and the display back panel 50. This step is the same as step S120 in the above embodiment and will not be described again.

[0092] S240: Reference Figure 20 At least some of the LED chips 20, except for the defective LED chip 20a, are separated from the growth substrate 10 using a laser peeling method. The separated LED chips 20 then fall along the channels formed by the insulating adhesive pillars 70 surrounding them onto the corresponding pad group 51. When the LED chips 20 fall into contact with the pad group 51, the insulating adhesive 60 connects the growth substrate 10 and the display backplate 50, fixing their relative positions and ensuring precise alignment between the LED chips 20 and the pad group 51. Therefore, when the LED chips 20 fall, they can accurately land on the corresponding pad group 51.

[0093] Since defective LED chips 20a have been detected in step S200, when transferring LED chips 20 in batches to the display backplane 50, defective LED chips 20a can be avoided, and only LED chips 20 with normal appearance and good wavelength consistency can be selected for transfer.

[0094] Specifically, the laser selectively irradiates the normal LED chip 20, avoiding the defective LED chip 20a, thereby causing the normal LED chip 20 to peel off from the growth substrate 10, while the defective LED chip 20a remains on the growth substrate 10. After the growth substrate 10 is removed, the defective LED chip 20a is removed along with the growth substrate 10. This ensures that the LED chips 20 transferred to the display backplane 50 are all normal in appearance and have good wavelength consistency, resulting in better light emission uniformity of the final fabricated display device and improving the quality of the fabricated display device.

[0095] S250: The LED chip 20 is heated and pressurized to bond to the corresponding pad group 51 on the display back plate 50.

[0096] Another embodiment of this application provides a mass transfer method; please refer to [reference needed]. Figure 21 and Figure 22 ,in, Figure 21 This is a flowchart of a mass transfer method provided in another embodiment of this application. Figure 22 yes Figure 21 The process flow diagram for step S350 shown is illustrated.

[0097] The mass transfer method provided in this embodiment specifically includes the following steps:

[0098] S300: Detect defective LED chips 20a on the growth substrate 10. This step is the same as step S200 in the above embodiment and will not be described again.

[0099] S310: Apply insulating adhesive 60 to the growth substrate 10, such that the insulating adhesive 60 is present between any two adjacent LED chips 20. This step is the same as step S100 in the above embodiment and will not be described again.

[0100] S320: The growth substrate 10 is positioned above the display backplate 50, such that the distance between the growth substrate 10 and the display backplate 50 is greater than the height of the LED chip 20. This step is the same as step S110 in the above embodiment and will not be described again.

[0101] S330: The insulating adhesive material 60 is heated to soften it. The softened insulating adhesive material 60 extends to bond with the display back panel 50, forming an insulating adhesive pillar 70 between the growth substrate 10 and the display back panel 50. This step is the same as step S120 in the above embodiment and will not be described again.

[0102] S340: At least a portion of the LED chips 20, excluding the defective LED chip 20a, are separated from the growth substrate 10 using a laser lift-off method. The separated LED chips 20 fall along the channels formed by the insulating adhesive pillars 70 around them onto the corresponding pad group 51. This step is the same as step S240 in the above embodiment and will not be described again.

[0103] S350: Reference Figure 22 Another LED chip 20 is added to the pad group 51 corresponding to the defective LED chip 20a. This prevents the pad group 51 corresponding to the defective LED chip 20a from being empty, resulting in more complete pixels on the final manufactured display device, thereby improving the display effect.

[0104] S360: The LED chip 20 is heated and pressurized to bond to the corresponding pad group 51 on the display backplate 50.

[0105] Specifically, a repair adhesive plate 80 can be used to bond a normal LED chip 20, and then the LED chip 20 can be transferred to the pad group 51 corresponding to the defective LED chip 20a.

[0106] Those skilled in the art should understand that, regardless of the above embodiments, the LED chip 20 ultimately needs to be soldered to the pad group 51. Specifically, the LED chip 20 can be soldered to the pad group 51 by heating and pressurizing, so that the LED chip 20 can be reliably connected, thereby improving the quality of the display device.

[0107] Based on the mass transfer method provided in any of the above embodiments, refer to Figure 26 Another embodiment of this application provides a display device, which specifically includes a display backplate 50 and a plurality of LED chips 20, wherein the LED chips 20 are transferred onto the display backplate 50 using the mass transfer method provided in any of the above embodiments.

[0108] This application also provides a display device, including a driving circuit and an LED light-emitting device as described in any embodiment of this application, wherein the LED light-emitting device and the driving circuit are electrically connected. In this application, the display device can be a mobile phone, tablet computer, laptop computer, or other display device with display and / or touch effects, and is not specifically limited thereto.

[0109] It should be understood that the application of this application 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 mass transfer method, characterized in that, include: An insulating adhesive is applied to the growth substrate so that there is an insulating adhesive between any two adjacent LED chips; The growth substrate is positioned above the display back panel, such that the distance between the growth substrate and the display back panel is greater than the height of the LED chip. The insulating adhesive is heated to soften it, and the softened insulating adhesive extends to bond with the display back panel to form an insulating pillar between the growth substrate and the display back panel. The LED chip is separated from the growth substrate, and the separated LED chip falls down along the channel formed by the insulating adhesive pillars around it onto the corresponding pad group. The LED chip is bonded to the corresponding pad group on the display back panel; Before softening the insulating adhesive, the mass transfer method further includes: providing a second groove between adjacent pad groups on the display back panel; Forming an insulating adhesive pillar between the growth substrate and the display backplate specifically includes: at least a portion of the insulating adhesive material bonded to the display backplate extending into the second groove to form an insulating adhesive pillar between the growth substrate and the display backplate.

2. The mass transfer method according to claim 1, characterized in that, After ensuring that the insulating adhesive is present between any two adjacent LED chips, the insulating adhesive is also spaced apart from the two adjacent LED chips; after forming an insulating column between the growth substrate and the display backplate, the insulating column is spaced apart from the two adjacent LED chips.

3. The mass transfer method according to claim 1, characterized in that, Applying an insulating adhesive to the growth substrate specifically includes: applying an insulating adhesive with a cross-section that is wide at both ends and narrow in the middle along its thickness direction to the growth substrate.

4. The mass transfer method according to claim 1, characterized in that, Forming an insulating adhesive column between the growth substrate and the display backplate specifically includes: forming an insulating adhesive column with a cross-section that is narrow at both ends and wide in the middle between the growth substrate and the display backplate.

5. The mass transfer method according to claim 1, characterized in that, After ensuring that the insulating adhesive is present between any two adjacent LED chips, the insulating adhesive is also made to be lower than or flush with the LED chips.

6. The mass transfer method according to claim 1, characterized in that, Before applying insulating adhesive to the growth substrate, the mass transfer method further includes: setting a first groove between any two adjacent LED chips on the growth substrate; After ensuring that the insulating adhesive is present between any two adjacent LED chips, at least a portion of the insulating adhesive is located within the first groove.

7. The mass transfer method according to any one of claims 1 to 6, characterized in that, Before applying insulating adhesive to the growth substrate, the mass transfer method further includes: detecting defective LED chips on the growth substrate; Separating the LED chip from the growth substrate specifically includes: separating at least a portion of the LED chips, excluding the defective LED chips, from the growth substrate; and then adding another LED chip to the pad group corresponding to the defective LED chip.

8. An LED display device, characterized in that, It includes a display backplate and a plurality of LED chips, wherein the plurality of LED chips are transferred onto the display backplate by the mass transfer method according to any one of claims 1 to 7.

9. A display device, characterized in that, It includes a driving circuit and the LED display device as described in claim 8, wherein the LED display device is electrically connected to the driving circuit.

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