TWI888106B - Micro-LED mass transfer method for full-color display - Google Patents

Abstract

The present invention is a method for mass transferring micro-LEDs for full-color displays, which is used to mass transfer red, blue and green micro-LEDs to a driving circuit board. The method comprises the following steps: providing a first adhesive substrate, which comprises a first carrier and a first adhesive sheet disposed on the first carrier; providing a dimethylsiloxane pickup body, which has a plurality of preset pickup surfaces, for respectively transferring multiple red, blue and green micro-LEDs of the same color to a driving circuit board; A plurality of micro-LEDs are transferred to the first adhesive sheet of the first adhesive substrate, so that the red, blue and green micro-LEDs are arranged adjacent to each other to form a plurality of sets of full-color micro-LEDs; a second adhesive substrate is provided, which includes a second carrier and a second adhesive sheet disposed on the second carrier; and the plurality of sets of full-color micro-LEDs on the first adhesive sheet are adhered to the second adhesive sheet and transferred to a driving circuit board.

Description

Micro-LED mass transfer method for full-color displays

The present invention is a method for mass transfer of micro-light-emitting diodes for full-color displays, and in particular, a method for mass transfer of red, green, and blue micro-light-emitting diodes (Micro LEDs).

In recent years, as the consumer market tends to require 3C products to have diversified functions, the use of internal space in 3C products has become increasingly stringent. In order to effectively utilize the space, the electronic components installed inside must also develop in the direction of miniaturization. In particular, the luminous materials of displays, such as light-emitting diodes, are also developing in the direction of miniaturization, thus developing micro light-emitting diodes (Micro LEDs).

If Micro LED is used as a light source to realize a high-resolution full-color display, it is necessary to transfer three red, green, and blue (R, G, B) light-emitting crystals of different wavelengths in large quantities and accurately to the driving circuit board. This transfer process is called mass transfer. In this transfer process, the Micro LED can be picked up and placed on the target substrate by the transfer material. As described in patent announcement number "I754454", polydimethylsiloxane (PDMS) is used as a transfer material in the current technology. In order to selectively pick up light-emitting crystals of different wavelengths for mass transfer and achieve the purpose of full-color display, PDMS will be designed into the required shape.

However, in actual situations, when PDMS is used as a transfer material to transfer Micro LED to a driving circuit board, reflow soldering is required to permanently bond the Micro LED to the substrate. However, due to the temperature of the "reflow soldering" process (generally at least greater than 130°C), PDMS will deform after the "reflow soldering" process. Especially when PDMS is used repeatedly for large-scale transfer, the accuracy will gradually get out of control. Moreover, since PDMS has a certain required shape, if it needs to be remade every time, it will not only be time-consuming and labor-intensive, and increase costs, but it may also be deformed by heat during the first use, resulting in the risk of transfer failure.

However, in the current knowledge field, there is no clear explanation on what materials to use to improve the above problems currently encountered.

In view of this, in the existing technology, there is still room for improvement in the mass transfer method of micro-LEDs used in full-color displays.

The present invention is a method for mass transferring micro-LEDs for full-color displays, which is used to mass transfer red, blue and green micro-LEDs to a driving circuit board. The method comprises the following steps: providing a first adhesive substrate, which comprises a first carrier and a first adhesive sheet disposed on the first carrier; providing a polydimethylsiloxane pickup body, which has a plurality of preset pickup surfaces, for respectively transferring the same color of micro-LEDs to a driving circuit board; A plurality of micro-LEDs are transferred to the adhesive sheet of the first adhesive substrate, so that the red, blue and green micro-LEDs are arranged adjacent to each other to form a plurality of sets of full-color micro-LEDs; a second adhesive substrate is provided, which includes a second carrier and a second adhesive sheet disposed on the second carrier; and the plurality of sets of full-color micro-LEDs on the first adhesive sheet are adhered to the second adhesive sheet and transferred to a driving circuit board.

In order to further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are only for reference and description and are not used to limit the present invention.

20: Micro LED

22: Pin

24: Red light micro diode

26: Green light micro diode

28: Blue light micro diodes

30: Support material

32: Polydimethylsiloxane (PDMS)

33: Pick up the face

35: First adhesive substrate

34: First adhesive sheet

36: The first carrier

37: Second adhesive substrate

38: Second adhesive sheet

39: Second carrier

40: Drive circuit board

X: The size and side length of the grain

Y: Grain thickness

H1: The depth of the die sinking into the first adhesive sheet

H2: The depth of the die sinking under the second adhesive sheet

Figure 1 is a schematic diagram of the red, green and blue light-emitting micro-diodes (Micro LEDs) of the present invention.

Figure 2 is a schematic diagram of the present invention using a polydimethylsiloxane (PDMS) pickup body to pick up red light for a micro-LED.

Figure 3 is a schematic diagram of the present invention using a polydimethylsiloxane (PDMS) pickup body to pick up green light for a micro-LED.

Figure 4 is a schematic diagram of the present invention using a polydimethylsiloxane (PDMS) pickup body to pick up blue light for a micro-LED.

Figures 5, 6, and 7 are schematic diagrams of the process of transferring the red light micro-LED to the first adhesive sheet using polydimethylsiloxane (PDMS) in the present invention.

Figure 8 is a schematic diagram of the present invention for transferring red, green and blue light-emitting micro diodes to the first adhesive sheet.

Figures 9, 10, and 11 are schematic diagrams of the process of transferring red, green, and blue light-emitting micro-diodes from the first adhesive sheet to the second adhesive sheet of the present invention.

Figures 12, 13, and 14 are schematic diagrams of the process of using a second adhesive sheet to transfer red, green, and blue light-emitting micro-diodes to a driving circuit board.

Please refer to Figure 1, which is a schematic diagram of the red, green and blue light-emitting micro-LED 20 of the present invention. The pin of the micro-LED is 22, and 24, 26 and 28 represent the red, green and blue light-emitting micro-LEDs, respectively. The side length of the micro-LED crystal is X (micrometer) (μm), and the thickness of the crystal is Y (micrometer) (μm).

Please refer to Figure 2, which is a schematic diagram of the present invention for picking up red light micro-LEDs using a polydimethylsiloxane (PDMS) pickup body. The polydimethylsiloxane (PDMS) 32 with the required pattern is designed on the support material 30, and it has a plurality of preset pickup surfaces 33, which are used to transfer a plurality of micro-LEDs of the same color to the first adhesive sheet 34 of the first adhesive substrate 35, and the red light micro-LED 24 is adhered to the polydimethylsiloxane (PDMS) 32 by picking.

Please refer to Figure 3, which is a schematic diagram of the present invention for picking up green light micro-LEDs using a polydimethylsiloxane (PDMS) pickup body. The polydimethylsiloxane (PDMS) 32 with the required pattern is designed on the support material 30, and it has a plurality of preset pickup surfaces 33, which are used to transfer a plurality of micro-LEDs of the same color to the first adhesive sheet 34 of the first adhesive substrate 35, and the green light micro-LED 26 is adhered to the polydimethylsiloxane (PDMS) 32 by picking. Because the picked green light micro-LED 26 is different from the red light micro-LED 24 in Figure 2, the design pattern of the polydimethylsiloxane (PDMS) 32 is different, and the schematic diagram is used here to illustrate the different positions.

Please refer to Figure 4, which is a schematic diagram of using a polydimethylsiloxane (PDMS) pickup body to pick up a blue light micro-LED. A polydimethylsiloxane (PDMS) 32 with a desired pattern is designed on a support material 30, and it has a plurality of preset pickup surfaces 33, which are used to transfer a plurality of micro-LEDs of the same color to the first adhesive sheet 34 of the first adhesive substrate 35, and the blue light micro-LED 28 is adhered to the polydimethylsiloxane (PDMS) 32 by picking. Because the blue light micro-LED 28 picked up is different from the red light micro-LED 24 in Figure 2 and the green light micro-LED 26 in Figure 3, the design pattern of the polydimethylsiloxane (PDMS) 32 is different. Here, only the schematic diagram is used to illustrate the different positions.

Please refer to Figures 5, 6 and 7, which are schematic diagrams of the invention for transferring the red light micro-LED to the first adhesive sheet using polydimethylsiloxane (PDMS), wherein the red light micro-LED 24 of Figure 2 is transferred to one side of the first adhesive sheet 34 of 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 pins 22 of the red light micro-LED 24 are adhered to the first adhesive sheet 34, and then the polydimethylsiloxane (PDMS) 32 on the supporting material 30 is removed from the red light micro-LED, and the red light micro-LED 24 is transferred to the first adhesive sheet 34.

Please refer to Figure 8, which is a schematic diagram of the present invention for transferring red, green and blue micro-LEDs to the first adhesive sheet, where the red 24, green 26 and blue 28 micro-LEDs are transferred to the first adhesive sheet 34, so that the red 24, green 26 and blue 28 micro-LEDs are arranged adjacent to each other to form a plurality of sets of full-color micro-LEDs, and the plurality of sets of full-color micro-LEDs (Micro LEDs) are sunken to a depth of H1 (micrometers) (μm) under the first adhesive sheet 34.

Please refer to Figures 9, 10, and 11, which are schematic diagrams of the first adhesive sheet of the present invention transferring the red, green, and blue micro-LEDs to the second adhesive sheet. Figure 9 is a diagram of transferring the red 24, green 26, and blue 28 micro-LEDs in Figure 8 to one surface of a second adhesive sheet 38 of a second adhesive substrate 37, and the other surface of the second adhesive sheet 38 is adhered to a second carrier 39. Figure 10 is a diagram of the other surface of the pins 22 of the red 24, green 26, and blue 28 micro-LEDs contacting the second adhesive sheet 38 during the transfer process. Figure 11 shows that after 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 through a transfer process, so that the red 24, green 26, and blue light 28 micro-LEDs are arranged adjacent to each other to form a plurality of sets of full-color micro-LEDs, and the plurality of sets of full-color micro-LEDs (Micro LEDs) are sunken to a depth of H2 (micrometers) (μm) under the second adhesive sheet.

Please refer to Figures 12, 13, and 14, which are schematic diagrams of the process of transferring the red, green, and blue micro-LEDs using the second adhesive sheet. Figure 12 is a diagram of transferring the red 24, green 26, and blue 28 micro-LEDs in Figure 11 to the driving circuit board 40. Figure 13 is a diagram of the pins 22 of the red 24, green 26, and blue 28 micro-LEDs contacting the driving circuit board 40 during the transfer process, and the micro-LEDs are permanently bonded to the driving circuit board through a reflow process. Figure 14 shows that after the second adhesive sheet 38 on the second carrier 39 is removed, the micro-LEDs of red light 24, green light 26, and blue light 28 are transferred to the driving circuit board 40 through the transfer process.

The side length of the micro-LED described in the present invention is X (micrometers), where X < 100 (micrometers) (μm), and the thickness is Y (micrometers) (μm), where Y < 15 (micrometers) (μm).

The material of the support material 30 is not limited in the present invention, and can be a rigid material such as metal, ceramic, glass, semiconductor wafer, etc., and can be designed to form a certain required pattern of dimethylsiloxane (PDMS), which is suitable for the subsequent bonding of micro light-emitting diodes (Micro LEDs) for transfer process.

The transfer material described in the present invention is polydimethylsiloxane (PDMS) 32, which is a known technology and will not be described in detail here. In addition, the thickness of polydimethylsiloxane is not an important technical feature of the present invention and does not need to be limited.

The first and second adhesive sheets 34 and 38 described in the present invention can be rubber-based, acrylic-based, vinyl-alkyl ether-based, polysiloxane-based, polyester-based, polyamide-based, urethane-based, polystyrene/diene copolymer-based, and acrylic (ester) copolymer-based.

One side of the first and second adhesive sheets 34 and 38 is adhered to the first and second carriers 36 and 39, wherein the first and second carriers 36 and 39 can be plastic films, glass, synthetic quartz, and metal. The plastic film can be polyester (such as PET), polyethylene (PE), polypropylene (PP), polyimide (PI), polyamide (PA), polyurethane (PU), cellulose triacetate (TAC), acrylic, and combinations thereof.

The contents of the above specific embodiments are for the purpose of describing the present invention in detail. However, such embodiments are for illustration only and are not intended to limit the present invention. Those skilled in the art can understand that various changes or modifications made to the present invention without departing from the scope defined by the scope of the attached patent application are part of the present invention.

22: Pin

24: Red light micro diode

26: Green light micro diode

28: Blue light micro diodes

37: Second adhesive substrate

38: Second adhesive sheet

39: Second carrier

40: Drive circuit substrate

Claims (5)

A method for mass transfer of micro-LEDs for full-color displays is used to mass transfer red, green and blue micro-LEDs to a driving circuit board. The transfer method includes the following steps; Providing a first adhesive substrate, which includes a first carrier and a first adhesive sheet disposed on the first carrier; A polydimethylsiloxane pickup body is provided, which has a plurality of preset pickup surfaces for transferring a plurality of micro-LEDs of the same color to the first adhesive sheet of the first adhesive substrate, so that the red, green and blue micro-LEDs are arranged adjacent to each other to form a plurality of sets of full-color micro-LEDs; and A second adhesive substrate is provided, which includes a second carrier and a second adhesive sheet disposed on the second carrier; and the second adhesive sheet is used to adhere a plurality of sets of full-color micro-light-emitting diodes on the first adhesive sheet, and then the plurality of sets of full-color micro-light-emitting diodes are transferred to the driving circuit board. As described in Item 1 of the patent application scope, the mass transfer method of micro-light-emitting diodes for full-color displays, wherein the first carrier of the first adhesive substrate is a plastic film, glass, synthetic quartz, or metal. As described in Item 1 of the patent application scope, the mass transfer method of micro-light-emitting diodes for full-color displays, wherein the second carrier of the second adhesive substrate is a plastic film, glass, synthetic quartz, or metal. As described in Item 1 of the patent application scope, a mass transfer method of micro-LEDs for full-color displays, wherein the side length of the micro-LEDs is X (micrometers), X < 100 (micrometers) (μm), and the thickness of the micro-LEDs is Y (micrometers) (μm), Y < 15 (micrometers) (μm). As described in item 1 of the patent application scope, the mass transfer method of micro-light-emitting diodes for full-color displays, wherein the first and second adhesive sheets can be rubber-based, acrylic-based, vinyl-alkyl ether-based, polysiloxane-based, polyester-based, polyamide-based, urethane-based, polystyrene/diene copolymer-based, and acrylic (ester) copolymer-based.

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