Micro light emitting diode mass transfer method for full-color display

Abstract

The invention discloses a micro light emitting diode mass transfer method for a full-color display. The transfer method is used for transferring a large amount of red, blue and green micro light emitting diodes to a driving circuit board, and comprises the following steps of: providing a first adhesive substrate which comprises a first carrier and a first adhesive sheet arranged on the first carrier; providing a dimethyl siloxane pick-up body which is provided with a plurality of preset pick-up surfaces and is used for respectively transferring a plurality of micro light-emitting diodes with the same color to the first adhesion sheet of the first adhesion substrate, so that the micro light-emitting diodes with red, blue and green colors are adjacently arranged to form a plurality of groups of full-color micro light-emitting diodes; providing a second adhesive base material, wherein the second adhesive base material comprises a second carrier and a second adhesive sheet arranged on the second carrier; and adhering the plurality of groups of full-color micro light-emitting diodes on the first adhesion sheet by using the second adhesion sheet, and transferring the full-color micro light-emitting diodes to a driving circuit board.

Description

Technical Field

[0001] This invention relates to a method for mass transfer of miniature light-emitting diodes for full-color displays, specifically a method for mass transfer of red, green, and blue miniature light-emitting diodes. Background Technology

[0002] In recent years, as the consumer market has increasingly demanded more diverse functions from 3C products, the requirements for internal space utilization have become more stringent. To improve effective space utilization, the electronic components inside must also be miniaturized. In particular, the light-emitting materials for displays, such as light-emitting diodes (LEDs), are also trending towards miniaturization, thus leading to the development of micro LEDs.

[0003] To achieve a high-resolution, full-color display using Micro LEDs as the light source, a large number of light-emitting chips of three different wavelengths—red, green, and blue (R, G, B)—must be precisely transferred onto the driving circuit substrate. This transfer process is called mass transfer. During this process, Micro LEDs can be picked up and placed onto the target substrate using transfer materials. As described in Taiwan Patent Publication No. I754454, current technology uses polydimethylsiloxane (PDMS) as the transfer material. To selectively pick up light-emitting chips of different wavelengths for mass transfer and achieve full-color display, PDMS is designed into the required shape.

[0004] However, in practice, when using PDMS as a transfer material to transfer Micro LEDs onto the driver circuit substrate, reflow soldering is required to permanently bond the Micro LEDs to the substrate. However, because the reflow soldering process involves temperatures (generally at least above 130°C), the PDMS deforms after the process. This is especially problematic when using PDMS repeatedly for large-scale transfers, leading to a gradual loss of accuracy. Furthermore, since PDMS has a specific required shape, remanufacturing it each time is not only time-consuming and labor-intensive, increasing costs, but also carries the risk of transfer failure due to heat deformation on the first use. Currently, there is no clear indication in the art of identifying materials to address these issues.

[0005] In view of this, there is still room for improvement in the existing mass transfer methods for miniature light-emitting diodes used in full-color displays. Summary of the Invention

[0006] To address the aforementioned deficiencies in the field, this application aims to provide a method for mass transfer of micro light-emitting diodes (Micro LEDs) for full-color displays. This method involves mass-transferring red, blue, and green micro LEDs onto a driver circuit board. The transfer method includes the following steps:

[0007] A first adhesive substrate is provided, which includes a first carrier and a first adhesive sheet disposed on the first carrier;

[0008] A polydimethylsiloxane (PDMS) pickup is provided, which has a plurality of preset pickup surfaces for transferring a plurality of miniature light-emitting diodes of the same color to the adhesive sheet of the first adhesive substrate, so that the red, blue and green miniature light-emitting diodes are arranged adjacent to each other to form a plurality of full-color miniature light-emitting diodes.

[0009] A second adhesive substrate is provided, which includes a second carrier and a second adhesive sheet disposed on the second carrier; and a complex array of full-color micro light-emitting diodes on the first adhesive sheet is adhered using the second adhesive sheet, and the diodes are transferred to a driving circuit board. Attached Figure Description

[0010] Figure 1 A schematic diagram of the red, green, and blue light-emitting micro-LEDs of this invention.

[0011] Figure 2 This is a schematic diagram of a miniature light-emitting diode that uses a polydimethylsiloxane pickup to pick up red light according to the present invention.

[0012] Figure 3 This is a schematic diagram of a miniature light-emitting diode using a polydimethylsiloxane pickup to pick up green light according to the present invention.

[0013] Figure 4 This is a schematic diagram of a miniature light-emitting diode using a polydimethylsiloxane pickup element to pick up blue light according to the present invention.

[0014] Figure 5-7 This is a schematic diagram illustrating the process of transferring a red-light-emitting micro-LED to a first adhesive sheet using polydimethylsiloxane according to the present invention.

[0015] Figure 8 This is a schematic diagram of the present invention for transferring miniature light-emitting diodes of red, green, and blue light onto a first adhesive sheet.

[0016] Figure 9-11 This is a schematic diagram illustrating the process of transferring a miniature light-emitting diode (LED) that emits red, green, and blue light from a first adhesive sheet to a second adhesive sheet according to the present invention.

[0017] Figure 12-14This is a schematic diagram illustrating the process of transferring miniature light-emitting diodes (LEDs) that emit red, green, and blue light onto a driver circuit board using a second adhesive sheet, according to the present invention.

[0018] [Symbol Explanation]

[0019] Micro LED (Micro Light Emitting Diode) 20

[0020] 22-pin connector

[0021] Red light miniature LED 24

[0022] Green miniature light-emitting diode 26

[0023] Blue light miniature LED 28

[0024] Support material 30

[0025] Polydimethylsiloxane (PDMS) 32

[0026] Pick up face 33

[0027] First adhesive substrate 35

[0028] First adhesive sheet 34

[0029] First carrier 36

[0030] Second adhesive substrate 37

[0031] Second adhesive sheet 38

[0032] Second carrier 39

[0033] Driver circuit board 40

[0034] Grain size side length X

[0035] Grain thickness Y

[0036] The grain is recessed to a depth H1 in the first adhesive sheet.

[0037] The grain is recessed to a depth H2 in the second adhesive sheet. Detailed Implementation

[0038] The technical solution of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0039] It should be particularly noted that similar substitutions and modifications made to this application are obvious to those skilled in the art, and they are all considered to be included in this application. Those skilled in the art can obviously make modifications or appropriate alterations and combinations to the methods and applications described herein without departing from the content, spirit, and scope of this application to implement and apply the technology of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0040] Unless otherwise specified, this application is conducted under standard conditions or conditions recommended by the manufacturer. The raw materials or excipients used, as well as the reagents or instruments used, whose manufacturers are not specified, are all conventional products that can be obtained commercially.

[0041] The following is a detailed description of this application.

[0042] like Figure 1 The diagram shows a schematic of the red, green, and blue light-emitting micro LED 20 of the present invention. The pin of the micro LED is 22, and pins 24, 26, and 28 represent red, green, and blue light-emitting micro LEDs, respectively. The side length of the micro LED chip is X (micrometers) and the thickness of the chip is Y (micrometers) (μm).

[0043] like Figure 2 The diagram shows a miniature light-emitting diode (LED) using a polydimethylsiloxane (PDMS) pickup body to pick up red light according to the present invention. The PDMS 32 with the required pattern is designed on the support material 30. It has a plurality of preset pickup surfaces 33, which are used to transfer a plurality of miniature LEDs of the same color to the first adhesive sheet 34 of the first adhesive substrate 35 respectively. The red light-emitting LED 24 is then attached to the PDMS 32 by pickup.

[0044] like Figure 3 The diagram illustrates the present invention's use of polydimethylsiloxane (PDMS) pickups to capture green light in a micro-LED. A PDMS 32 with the desired pattern is designed on a support material 30. This PDMS 32 has multiple pre-defined pickup surfaces 33, used to transfer multiple micro-LEDs of the same color to the first adhesive sheet 34 of the first adhesive substrate 35. The green light-emitting micro-LED 26 is then adhered to the PDMS 32 via pickup. Because the green light-emitting micro-LED 26 differs from the red light-emitting micro-LED 24 in Figure 2, the design pattern of the PDMS 32 is different; only the positional difference is shown schematically here.

[0045] like Figure 4 The diagram illustrates the present invention's use of polydimethylsiloxane (PDMS) pickups to capture blue light in a micro-LED. A PDMS 32 with the desired pattern is designed on a support material 30. It has a plurality of pre-defined pickup surfaces 33, used to transfer a plurality of micro-LEDs of the same color to the first adhesive sheet 34 of the first adhesive substrate 35. The blue light-emitting micro-LED 28 is then adhered to the PDMS 32 via pickup. Because the captured blue light-emitting micro-LED 28 differs from the red light-emitting micro-LED 24 in Figure 2 and the green light-emitting micro-LED 26 in Figure 3, the design pattern of the PDMS 32 is different; only the different positions are shown in the schematic diagram.

[0046] like Figure 5-7 The diagram illustrates the process of transferring a red-light-emitting micro-LED to a first adhesive sheet using polydimethylsiloxane (PDMS). Figure 2 The red light-emitting micro LED 24 is transferred to one side of the first adhesive sheet 34 on the first adhesive substrate 35, and the other side of the first adhesive sheet 34 is adhered to a first carrier 36. During the transfer process, the pin 22 of the red light-emitting micro LED 24 is adhered to the first adhesive sheet 34. Then, the polydimethylsiloxane (PDMS) 32 on the support material 30 is removed from the red light-emitting micro LED, and the red light-emitting micro LED 24 is transferred to the first adhesive sheet 34.

[0047] like Figure 8 The diagram shows the transfer of red, green, and blue micro-light-emitting diodes (LEDs) to the first adhesive sheet according to the present invention. The red LED 24, green LED 26, and blue LED 28 are transferred to the first adhesive sheet 34, so that the red LED 24, green LED 26, and blue LED 28 are arranged adjacent to each other to form a complex array of full-color micro-light-emitting diodes. The depth of the complex array of full-color micro-light-emitting diodes (Micro LEDs) in the first adhesive sheet 34 is H1μm.

[0048] like Figure 9-11 The diagram shown illustrates how the first adhesive sheet of the present invention transfers miniature light-emitting diodes (LEDs) emitting red, green, and blue light to the second adhesive sheet. Figure 9 To be Figure 8 The red light 24, green light 26, and blue light 28 micro light-emitting diodes are transferred to one side of the second adhesive sheet 38 on the second adhesive substrate 37, and the other side of the second adhesive sheet 38 is adhered to a second carrier 39. Figure 10 During the transfer process, the other side of the pin 22 of the miniature light-emitting diodes 24 (red light), 26 (green light), and 28 (blue light) is brought into contact with the second adhesive sheet 38. Figure 11After the first adhesive sheet 34 on the first carrier 36 is removed, the red light 24, green light 26, and blue light 28 micro LEDs are transferred to the second adhesive sheet 38 via a transfer process, so that the red light 24, green light 26, and blue light 28 micro LEDs are arranged adjacent to each other to form a complex array of full-color micro LEDs, and the depth of the complex array of full-color micro LEDs (MicroLEDs) in the second adhesive sheet is H2μm.

[0049] like Figure 12-14 The diagram shown illustrates the process of transferring red, green, and blue light-emitting diodes using a second adhesive sheet according to the present invention. Figure 12 To be Figure 11 The red, green, and blue miniature light-emitting diodes 24, 26, and 28 are transferred to the driver circuit board 40. Figure 13 During the transfer process, the pins 22 of the red light 24, green light 26, and blue light 28 micro LEDs are brought into contact with the driver circuit board 40. Through a reflow soldering process, the micro LEDs are permanently bonded to the driver circuit board. Figure 14 After the second adhesive sheet 38 on the second carrier 39 is removed, the miniature light-emitting diodes of red light 24, green light 26, and blue light 28 are transferred to the driver circuit board 40 via a transfer process.

[0050] The micro light-emitting diode described in this invention has a side length of X, where X < 100 (micrometers) (μm), and a thickness of Y, where Y < 15 (micrometers) (μm).

[0051] The material of the support material 30 is not limited in this invention. It can be a rigid material such as metal, ceramic, glass, or semiconductor wafer. Dimethylsiloxane (PDMS) can be designed to form a certain required pattern, which is suitable for subsequent bonding of micro light-emitting diodes (Micro LEDs) for transfer processes.

[0052] The transfer material described in this invention is polydimethylsiloxane (PDMS) 32, which is a known technology and will not be described further here. Furthermore, the thickness of the polydimethylsiloxane is not a key technical feature of this invention and does not need to be limited.

[0053] The first and second adhesive sheets 34 and 38 described in this invention may be rubber-based, propylene-based, vinyl-alkyl ether-based, polysiloxane-based, polyester-based, polyamide-based, ethyl carbamate-based, polystyrene / diene copolymer-based, or acrylate copolymer-based.

[0054] One side of the first and second adhesive sheets 34 and 38 is attached to the first and second carriers 36 and 39.

[0055] The first and second carriers 36 and 39 can be plastic films, glass, synthetic quartz, or metals. The plastic films can be polyester (such as PET), polyethylene (PE), polypropylene (PP), polyimide (PI), polyamide (PA), polyurethane (PU), cellulose triacetate (TAC), acrylic, or combinations thereof.

[0056] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of this application. It should be noted that, for those skilled in the art, several improvements and modifications can be made to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A method for mass transfer of miniature light-emitting diodes (LEDs) for a full-color display, comprising the method of mass-transferring red, green, and blue LEDs onto a driver circuit board, the method comprising: A first adhesive substrate is provided, the first adhesive substrate including a first carrier and a first adhesive sheet disposed on the first carrier; A polydimethylsiloxane pickup is provided, the polydimethylsiloxane pickup having a plurality of predetermined pickup surfaces for transferring a plurality of micro-light-emitting diodes of the same color onto the first adhesive sheet of the first adhesive substrate, such that the red, green, and blue micro-light-emitting diodes are arranged adjacent to each other to form a plurality of arrays of full-color micro-light-emitting diodes; and A second adhesive substrate is provided, the second adhesive substrate including a second carrier and a second adhesive sheet disposed on the second carrier; and The second adhesive sheet is used to attach the complex array of full-color miniature light-emitting diodes on the first adhesive sheet, and then the miniature light-emitting diodes are transferred to the driving circuit board.

2. The method for mass transfer of miniature light-emitting diodes for full-color displays according to claim 1, wherein, The first carrier of the first adhesive substrate is a plastic film, glass, synthetic quartz, or metal.

3. The method for mass transfer of miniature light-emitting diodes for full-color displays according to claim 1, wherein, The second carrier of the second adhesive substrate is a plastic film, glass, synthetic quartz, or metal.

4. The method for mass transfer of miniature light-emitting diodes for full-color displays according to claim 1, wherein, The micro LED has a side length of <100μm and a thickness of <15μm.

5. The method for mass transfer of miniature light-emitting diodes for a full-color display according to claim 1, wherein, The first adhesive sheet and the second adhesive sheet are selected from one or more of the following: rubber-based, acrylic-based, vinyl-alkyl ether-based, polysiloxane-based, polyester-based, polyamide-based, ethyl carbamate-based, polystyrene / diene copolymer-based, and acrylate copolymer-based.

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