Method for manufacturing microLED devices, color-converting optical sheet material, and optical instrument

Abstract

To enable the provision of a color conversion layer without causing a problem due to a conventional photolithography method, screen printing method, or inkjet method in a case where a pixel of a micro-LED device is formed from micro-LED subpixels including color conversion layers such as a red conversion layer, a green conversion layer, and if necessary a blue conversion layer, or a white conversion layer provided right over a monochromatic micro-LED emitting light in ultraviolet to blue wavelength regions.SOLUTION: In a micro-LED device in which a color conversion layer is disposed right over a micro-LED disposed on a circuit board, a micro-LED is disposed on a circuit board, a color conversion layer of a color conversion optical sheet material having the color conversion layer formed on one surface of a light-transmissive sheet base material is disposed to face the micro-LED, and the color conversion layer of the color conversion optical sheet material is irradiated with laser light from the light-transmissive sheet base material side, so that the color conversion layer is transferred right onto the micro-LED.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing microLED devices such as full-color microLED (Light Emitting Diode) display panels and microLED white light source panels, a color conversion optical sheet material used in the manufacturing method, and an optical device equipped with a microLED device. [Background technology]

[0002] A typical structure of a full-color LED display, which possesses desirable characteristics such as high brightness, low power consumption, high contrast, and long lifespan, consists of an array of a vast number of pixels on a display circuit board. Each pixel is composed of three subpixels, namely a red LED, a green LED, and a blue LED. Such a full-color LED display is manufactured, for example, by forming LEDs on separate semiconductor wafers for each color using microfabrication methods, mounting red LEDs to all pixels on the display circuit board, followed by green LEDs, and finally blue LEDs. Specifically, the vast number of LEDs of each color fabricated on the semiconductor wafer are diced into individual pieces, transferred to a transfer substrate, and then re-transferred to the display circuit board via a conductive adhesive layer.

[0003] Incidentally, in recent years, there has been a growing demand for 4K and 8K resolution full-color displays. As a result, attempts have been made to construct full-color microLED display panels using microLEDs with sides of approximately 100 μm or less. However, manufacturing such high-resolution full-color microLED display panels in the conventional way requires fabricating a vast number of tiny LEDs on different semiconductor wafers for each color, separating them into individual pieces, and then sequentially mounting them onto the display circuit board for each color. This inevitably leads to a decrease in yield and an extension of the cycle time.

[0004] Therefore, it has been proposed to construct a micro-LED full-color display panel by combining micro-LED subpixels, each having a red conversion layer, a green conversion layer, and, if necessary, a blue conversion layer, directly above a monochromatic micro-LED emitting light in the ultraviolet to blue wavelength range, to form pixels (Patent Document 1). According to this technology, only one type of monochromatic micro-LED is required, which significantly reduces the effort involved in forming, framing, and mounting the micro-LEDs themselves, thereby suppressing yield reduction and cycle time extension.

[0005] On the other hand, methods for providing a color conversion layer as a color converter directly above such micro-LED subpixels include photolithography, screen printing, and inkjet printing. The photolithography method involves repeatedly performing a series of steps for each color, such as coating, exposure, development, baking, etching, and washing, on a carrier film to sequentially form a red conversion layer, a green conversion layer, and a blue conversion layer. The resulting color conversion layer of the color conversion optical film is then aligned and pressure-transferred onto a micro-LED array with a black matrix, and this process is repeated for each color. The screen printing method involves repeatedly coating and drying a color conversion layer-forming composition on a carrier film via a screen plate to sequentially form a red conversion layer, a green conversion layer, and a blue conversion layer. This layer is then aligned and pressure-transferred onto a micro-LED array with a black matrix, and this process is repeated for each color. The inkjet method involves directly ejecting color conversion layer-forming composition inks onto a micro-LED array with a black matrix, and then curing them. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Special Publication No. 2016-523450 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, both photolithography and screen printing methods involve a large number of steps, leading to reduced yield and extended cycle times in the formation of the color conversion layer. Furthermore, controlling the thickness of the color conversion layer and aligning it with monochromatic micro-LEDs are difficult. This alignment becomes even more challenging when a black matrix is ​​formed around the pixels. Moreover, because the color conversion layer goes through numerous steps, controlling its transfer properties to the LED is difficult. In addition, if so-called quantum dot materials are used for the color conversion layer, there is a problem that the color conversion function of the quantum dot materials may be impaired due to oxidation, etc.

[0008] On the other hand, while the inkjet method has fewer steps and is relatively easy to align compared to the photolithography and screen printing methods, and does not significantly impair the color conversion function of quantum dot materials, it basically ejects a single-color color conversion layer formation composition ink from a single inkjet nozzle. Therefore, forming red, green, and blue color conversion layers across the entire surface of a micro-LED array for a full-color display requires long inkjet operations. Furthermore, when attempting to supply the color conversion layer formation composition ink directly above very small micro-LEDs with sides of 30 μm or less, the nozzle diameter must be reduced, raising concerns about clogging. Controlling the viscosity to properly eject such color conversion layer formation composition inks is also difficult.

[0009] The present invention aims to solve the aforementioned conventional problems, and when constructing pixels of a microLED device from microLED subpixels, in which a color conversion layer such as a red conversion layer, a green conversion layer, and optionally a blue conversion layer or a white conversion layer is provided directly above a monochromatic microLED emitting light in the ultraviolet to blue wavelength range, the objective is to provide a color conversion layer without causing problems associated with conventional photolithography, screen printing, or inkjet methods. [Means for solving the problem]

[0010] The inventors have found that the above object can be solved by providing a color conversion layer directly above the micro-LED using a laser lift-off method known as one of the manufacturing techniques for semiconductor devices, and have completed the present invention.

[0011] That is, as a first aspect, the present invention provides a method for manufacturing a micro-LED device in which a color conversion layer is disposed directly above a micro-LED disposed on a circuit board, the method comprising the following steps (a), (b), and (c).

[0012] Step (a) A step of disposing a micro-LED on a circuit board; Step (b) A step of opposing the color conversion layer of a color conversion optical sheet material, in which the color conversion layer is formed on one side of a light-transmissive sheet substrate, to the micro-LED disposed on the circuit board; and Step (c) A step of transferring the color conversion layer of the portion irradiated with the laser light directly above the micro-LED by irradiating the color conversion layer of the color conversion optical sheet material with laser light from the light-transmissive sheet substrate side.

[0013] Further, as a second aspect, the present invention provides a method for manufacturing a micro-LED device in which one pixel of the micro-LED device includes three blue micro-LEDs as sub-pixels, a red conversion layer is formed directly above one of the three blue micro-LEDs, a green conversion layer is formed directly above another one of the three blue micro-LEDs, and no color conversion layer is formed directly above the remaining one of the three blue micro-LEDs, the method comprising the following steps (A), (B), and (C).

[0014] Step (A) A step of disposing blue micro-LEDs on a circuit board; Step (B) For one of the three blue micro-LEDs constituting one pixel of the micro-LED device, the red conversion layer of the red conversion optical sheet material in which the red conversion layer is formed on one side of the light-transmissive sheet substrate is opposed to the blue micro-LED, and for another blue LED, the green conversion layer of the green conversion optical sheet material in which the green conversion layer is formed on one side of the light-transmissive sheet substrate is opposed to the blue LED; and Step (C) With respect to the red conversion layer of the red conversion optical sheet material and the green conversion layer of the green conversion optical sheet material, by irradiating laser light from the light-transmissive sheet substrate side by the laser lift-off method, the red conversion layer and the green conversion layer of the portion irradiated with the laser light are transferred directly above the blue micro-LED.

[0015] Furthermore, as a third aspect, the present invention provides a method for manufacturing a micro-LED device in which one pixel of the micro-LED device includes three ultraviolet micro-LEDs as sub-pixels, a red conversion layer is formed directly above one of the three ultraviolet micro-LEDs, a green conversion layer is formed directly above another ultraviolet micro-LED, and a blue conversion layer is formed directly above the remaining ultraviolet micro-LED, the method including the following steps (AA), step (BB), and step (CC).

[0016] Step (AA) A step of disposing an ultraviolet micro-LED on a circuit board; Step (BB) For one of the three ultraviolet micro-LEDs constituting one pixel of the micro-LED device, the red conversion layer of the red conversion optical sheet material in which the red conversion layer is formed on one side of the light-transmissive sheet substrate is opposed to the ultraviolet micro-LED, and for another ultraviolet micro-LED, the green conversion layer of the green conversion optical sheet material in which the green conversion layer is formed on one side of the light-transmissive sheet substrate is opposed to the ultraviolet micro-LED, and for the remaining one ultraviolet micro-LED, the blue conversion layer of the blue conversion optical sheet material in which the blue conversion layer is formed on one side of the light-transmissive sheet substrate is opposed to the ultraviolet micro-LED; and Process (CC) A process in which the red conversion layer of a red conversion optical sheet material, the green conversion layer of a green conversion optical sheet material, and the blue conversion layer of a blue conversion optical sheet material are irradiated with laser light from the light-transmitting sheet substrate side using a laser lift-off method, thereby transferring the red conversion layer, green conversion layer, and blue conversion layer in the irradiated portion onto an ultraviolet micro-LED.

[0017] In addition, the present invention, in a fourth aspect, is a color conversion optical sheet material for arranging a color conversion layer in a microLED using a laser lift-off method, It comprises a light-transmitting sheet substrate and a color conversion layer disposed on one side thereof. The color conversion layer is a curable resin composition in which phosphor particles or quantum dot particles that emit red, green, or white fluorescence upon irradiation with blue laser light, or phosphor particles or quantum dot particles that emit red, green, blue, or white fluorescence upon irradiation with ultraviolet laser light, are dispersed, and the tack force according to JIS Z0237 is 0.1 MPa or more. We provide a color-converting optical sheet material.

[0018] Furthermore, in a fifth aspect, the present invention provides an optical device equipped with a microLED device on which the color conversion layer of the color conversion optical sheet material of the present invention is disposed on the surface, such as a full-color display panel or white light source panel for a mobile phone, personal computer, television set, VR device, or monitor. [Effects of the Invention]

[0019] In the manufacturing method of the microLED device of the present invention, when forming a color conversion layer directly on top of the microLED, a laser lift-off method is used with a color conversion optical sheet material in which a color conversion layer is formed on a light-transmitting sheet substrate. As a result, the following effects can be obtained.

[0020] *Since the color conversion layer is in film form, its thickness can be easily controlled. * Because the laser irradiation area can be narrowed to a very small size, a color conversion layer can be formed on a very small micro-LED with sides of about 10 μm. *The color conversion layer can be detached from the color conversion optical sheet material in a very short time and deposited onto the micro-LED, making it easy to perform rapid mass transfer processing of micro-LEDs when manufacturing 4K or 8K resolution LED devices. *Because the color conversion layer is in film form, the need to consider the transfer properties between the micro-LED and the color conversion layer is reduced, and the peeling balance can be easily controlled. *Even if a black matrix is ​​formed around the pixels, the color conversion layer can be easily detached from the color conversion optical sheet material and easily transferred to the micro-LED. *Since the color conversion layer is in film form, viscosity control, which is required for color conversion layer-forming inks applied to inkjet methods, is unnecessary, and the degree of freedom in the constituent materials of the color conversion layer can be increased. [Brief explanation of the drawing]

[0021] [Figure 1A] This is a process diagram illustrating a method for manufacturing a microLED device according to a first aspect of the present invention. [Figure 1B] This is a process diagram illustrating a method for manufacturing a microLED device according to a first aspect of the present invention. [Figure 2A] This is a process diagram illustrating a method for manufacturing a microLED device according to a first aspect of the present invention. [Figure 2B] This is a process diagram illustrating a method for manufacturing a microLED device according to a first aspect of the present invention. [Figure 3] This is a process diagram illustrating a method for manufacturing a microLED device according to a first aspect of the present invention. [Figure 4] This is a process diagram illustrating a method for manufacturing a microLED device according to a second aspect of the present invention. [Figure 5A] This is a process diagram illustrating a method for manufacturing a microLED device according to a second aspect of the present invention. [Figure 5B] This is a process diagram illustrating a method for manufacturing a microLED device according to a second aspect of the present invention. [Figure 5C] This is a process diagram illustrating a method for manufacturing a microLED device according to a second aspect of the present invention. [Figure 6A] This is a process diagram illustrating a method for manufacturing a microLED device according to a third aspect of the present invention. [Figure 6B] This is a process diagram illustrating a method for manufacturing a microLED device according to a third aspect of the present invention. [Figure 6C] This is a process diagram illustrating a method for manufacturing a microLED device according to a third aspect of the present invention. [Figure 6D] This is a process diagram illustrating a method for manufacturing a microLED device according to a third aspect of the present invention. [Figure 7A] This is a schematic cross-sectional view of a color-converting optical sheet material according to a fourth embodiment of the present invention. [Figure 7B] This is a schematic cross-sectional view of a color-converting optical sheet material according to a fourth embodiment of the present invention. [Modes for carrying out the invention]

[0022] The present invention will be described in detail below with reference to the drawings. In each figure, the same reference numerals represent the same or equivalent components.

[0023] <<First aspect of the present invention>> A first aspect of the present invention is a method for manufacturing a microLED device in which a color conversion layer is placed directly above a microLED that is arranged on a circuit board (specifically, on a circuit wiring terminal (not shown)). This manufacturing method comprises the following steps (a), (b), and (c). Each step will be described in detail.

[0024] <Process (a)> Step (a) is a step of arranging microLEDs on a circuit board such as a display substrate. In step (a), the arrangement of microLEDs on the circuit board can be done by bonding a microLED wafer 2, on which multiple microLEDs 1 are formed, to the circuit board 3, as shown in Figure 1A. This enables mass transfer of microLEDs. Bonding the circuit board 3 and the microLED wafer 2 can be done by known methods, for example, by solder reflow. Alternatively, it can be done by thermocompression bonding via a conductive adhesive film, anisotropic conductive film, or insulating adhesive film. Electrical connection between the microLEDs 1 and the circuit board 3 can also be done by known methods. For example, it can be done through through holes (not shown) formed in the microLED wafer 2.

[0025] Furthermore, in step (a), the placement of the microLEDs 1 on the circuit board 3 can also be performed by a known laser lift-off method (see, for example, Japanese Patent Application Publication No. 2017-157724) or a similar method. For example, in order to align the pitch of the microLEDs with the pitch on the circuit board, the microLEDs on the LED wafer can be transferred onto an adhesive silicone sheet (PDMS) by the laser lift-off method. Next, the adhesive silicone sheet on which the microLEDs have been transferred can be bonded to a glass substrate (light-transmitting sheet substrate) on which a curable polyimide layer has been formed by coating. Subsequently, the adhesive silicone sheet can be peeled off to obtain the glass substrate on which the microLEDs have been placed via the curable polyimide layer as the light-transmitting sheet substrate 4. Next, as shown in Figure 1B, the microLEDs 1 of the light-transmitting sheet substrate 4 can be aligned with the circuit board 3, and laser light can be irradiated onto the microLEDs 1 from the light-transmitting sheet substrate 4 side. This can be done by transferring (or transferring) the laser-irradiated microLEDs 1, along with the curable polyimide layer (not shown), to the circuit board 3. The laser lift-off conditions, such as laser wavelength, laser power, and laser irradiation time, can be appropriately determined according to the size of the laser irradiation target and the type of constituent material. Commercially available laser lift-off devices (such as Invisi-LUM-XTR, Shin-Etsu Chemical Co., Ltd., etc.) can be used to implement the laser lift-off method. Furthermore, the placement of the micro-LEDs 1 on the circuit board 3 can also be performed using a transfer method with a known stamping material (for example, Japanese Patent Application Publication No. 2021-141160).

[0026] Prior to step (a), it is preferable to place a conductive film, such as an anisotropic conductive film 5, at a predetermined position (e.g., a wiring terminal) on the circuit board 3 where the microLED 1 is to be placed, as shown in Figure 1B, in order to electrically connect the circuit board 3 and the microLED 1. In this case, the anisotropic conductive film 5 may be placed by thermocompression bonding, or individual pieces of the anisotropic conductive film 5 may be placed by the laser lift-off method. More specifically, this can be done by irradiating a layered anisotropic conductive layer or individual pieces thereof laminated on one side of a light-transmitting sheet substrate with laser light from the light-transmitting sheet substrate side, and transferring the anisotropic conductive layer or individual pieces thereof in the irradiated portion of the laser light to a predetermined position on the circuit board before the microLED is placed. As a result, the anisotropic conductive film does not completely cover the entire circuit board, making it preferable to use the microLED device for transparent display applications, and also increasing the degree of freedom in circuit design, such as making it possible to provide repair circuits and other circuits. Laser lift-off conditions, such as laser wavelength, laser power, and laser irradiation time, can be appropriately determined according to the size of the object being laser-irradiated and the type of constituent material.

[0027] <Process (b)> Step (b) is a step in which the color conversion layer 22 of the color conversion optical sheet material 20, which has a color conversion layer 22 formed on one side of a light-transmitting sheet substrate 21, is brought into contact with the micro LED 1 which is placed on the circuit board 3, as shown in Figure 2A. In this case, it is preferable to arrange the color conversion layer 22 as individual pieces, as shown in Figure 2A. This ensures that no excess material adheres to the circuit board 3, so as not to interfere with the mounting of other components, and also ensures good repairability of the micro LED. Alternatively, as shown in Figure 2B, the color conversion layer 22 may be in the form of a layer that covers a relatively large area of ​​the light-transmitting sheet substrate 21. In the color conversion optical sheet material 20, known methods can be used as methods for arranging the color conversion layer 22 as individual pieces on the light-transmitting sheet substrate 21. For example, the color conversion layer 22 can be made into individual pieces by photolithography, screen printing, inkjet printing, etc., but it can also be made into individual pieces by laser lift-off. Laser lift-off conditions, such as laser wavelength, laser power, and laser irradiation time, can be appropriately determined according to the size of the object to be irradiated and the type of constituent material.

[0028] The color conversion layer 22 is a layer that emits fluorescence in other wavelength ranges when irradiated with light emitted by a micro-LED. Specifically, it is a layer that emits red fluorescence, green fluorescence, or white fluorescence when irradiated with blue light, or a layer that emits red fluorescence, green fluorescence, blue fluorescence, or white light when irradiated with ultraviolet light emitted by a micro-LED. Such a color conversion layer 22 is a powdered color conversion material dispersed in a thermosetting resin composition, and the details thereof will be described in the fourth embodiment of the present invention.

[0029] <Process (c)> Step (c), as shown in Figure 3, is a step in which laser light L is irradiated from the light-transmitting sheet substrate 21 side to individual pieces of the color conversion layer 22 of the color conversion optical sheet material 20 using the laser lift-off method, thereby transferring the portion of the color conversion layer 22 irradiated with laser light onto the micro-LED 1. In Figure 3, the color conversion layer 22 is arranged as individual pieces on the color conversion optical sheet material 20. Such a color conversion optical sheet material 20 can be created by known methods, such as the inkjet method, but it can also be created by removing the color conversion layer 22 in positions other than those to be left as individual pieces using the laser lift-off method. Laser lift-off conditions such as laser wavelength, laser output, and laser irradiation time can be appropriately determined according to the size of the laser irradiation target and the type of constituent material. The transferred color conversion layer 22 can be stably fixed to the micro-LED 1 by thermocompression bonding, thermal aging, etc., as needed. If necessary, the micro-LED with the color conversion layer can be resin-encapsulated. In this case, the entire circuit board on which the micro-LED with the color conversion layer is provided may be resin-encapsulated.

[0030] Furthermore, "placing directly above" the microLED1 means that it may be placed so as to be in direct contact with the light-emitting surface of the microLED, or a protective film such as a silicone film may be interposed on the light-emitting surface.

[0031] <<Second aspect of the present invention>> A second aspect of the present invention is a specific example of the first aspect, and is a method for manufacturing a microLED device using only blue microLEDs that emit blue light in the wavelength range of 430 to 500 nm as microLEDs. As shown in Figure 4, this microLED device has a structure in which blue microLEDs 40a, 40b, and 40c are arranged on a circuit board 41 via an anisotropic conductive film 5. More specifically, one pixel of the microLED device comprises three blue microLEDs 40a, 40b, and 40c as subpixels, with a red conversion layer 22R formed directly above one of the three blue microLEDs 40a, a green conversion layer 22G formed directly above another blue microLED 40b, and no color conversion layer formed directly above the remaining blue microLED 40c. This manufacturing method comprises the following steps (A), (B), and (C), and is consistent with the first aspect of the present invention, and each step will be described below.

[0032] <Process (A)> First, as shown in Figure 5A, blue micro-LEDs 40a, 40b, and 40c are placed on the circuit board 41. These three blue micro-LEDs constitute one pixel of the micro-LED device.

[0033] <Process (B)> Next, as shown in Figure 5B, for one of the three blue micro-LEDs constituting one pixel of the micro-LED device, the red conversion layer 22R of the red conversion optical sheet material 20R, which has a red conversion layer 22R formed on one side of the light-transmitting sheet substrate 21, is placed opposite to the blue micro-LED 40a, and for another blue LED 40b, the green conversion layer 22G of the green conversion optical sheet material 20G, which has a green conversion layer 22G formed on one side of the light-transmitting sheet substrate 21, is placed opposite to the green conversion layer 22G of the green conversion optical sheet material 20G.

[0034] In step (B), the red conversion optical sheet material 20R and the green conversion optical sheet material 20G may be separate films, but the red conversion layer 22R and the green conversion layer 22G may be arranged alternately, preferably as individual pieces, on a common light-transmitting sheet substrate 21. Known methods can be used to form the individual pieces, but the laser lift-off method is preferred because it shortens the arrangement time of the color conversion layers.

[0035] <Process (C)> Next, as shown in Figure 5C, by irradiating the red conversion layer 22R of the red conversion optical sheet material 20R and the green conversion layer 22G of the green conversion optical sheet material 20G with laser light from the light-transmitting sheet substrate 21 side using the laser lift-off method, the red conversion layer 22R and green conversion layer 22G in the irradiated portion are transferred onto the blue micro-LEDs 40a and 40b, thereby manufacturing a micro-LED device having pixels as shown in Figure 4. The order of transfer of the color conversion layers can be changed as needed. In addition, the micro-LEDs on which the color conversion layers are arranged can be resin-encapsulated as needed. In this case, the entire circuit board on which the micro-LEDs with the color conversion layers are arranged may be resin-encapsulated.

[0036] <<Third aspect of the present invention>> A third aspect of the present invention is a specific example of the first aspect, and is a method for manufacturing a microLED device using only ultraviolet LEDs that emit ultraviolet light in the wavelength range of 300 to 400 nm as microLEDs. As shown in Figure 6A, one pixel comprises three ultraviolet microLEDs 50a, 50b, and 50c as subpixels, with a red conversion layer 22R formed directly above one of the three ultraviolet microLEDs 50a, a green conversion layer 22G formed directly above another ultraviolet microLED 50b, and a blue conversion layer 22B formed directly above the remaining ultraviolet microLED 50c. This manufacturing method comprises the following steps (AA), (BB), and (CC), and is similar to the first aspect of the present invention, and each step will be described below.

[0037] <Process (AA)> First, as shown in Figure 6A, ultraviolet micro-LEDs 50a, 50b, and 50c are placed on the circuit board 51. These three ultraviolet micro-LEDs constitute one pixel of the micro-LED device.

[0038] <Process (BB)> Next, as shown in Figure 6B, for one of the three ultraviolet micro-LEDs constituting one pixel of the micro-LED device, the red conversion layer 22R of the red conversion optical sheet material 20R, which has a red conversion layer 22R formed on one side of the light-transmitting sheet substrate 21, is placed opposite to one ultraviolet micro-LED 50a; for another ultraviolet micro-LED 50b, the green conversion layer 22G of the green conversion optical sheet material 20G, which has a green conversion layer 22G formed on one side of the light-transmitting sheet substrate 21, is placed opposite to one ultraviolet micro-LED 50c; and for the remaining ultraviolet micro-LED 50c, the blue conversion layer 22B of the blue conversion optical sheet material 20B, which has a blue conversion layer 22B formed on one side of the light-transmitting sheet substrate 21, is placed opposite to one ultraviolet micro-LED 50c.

[0039] <Process (CC)> Next, as shown in Figure 6C, by irradiating the red conversion layer 22R of the red conversion optical sheet material 20R, the green conversion layer 22G of the green conversion optical sheet material 20G, and the blue conversion layer 22B of the blue conversion optical sheet material 20B with laser light from the light-transmitting sheet substrate 21 side using the laser lift-off method, the red conversion layer 22R, green conversion layer 22G, and blue conversion layer 22B in the irradiated portion are transferred onto the ultraviolet micro-LEDs 50a, 50b, and 50c, thereby manufacturing a micro-LED device having pixels as shown in Figure 6D. The order of transfer of the color conversion layers can be changed as needed. In addition, the micro-LEDs on which the color conversion layers are arranged can be resin-encapsulated as needed. In this case, the entire circuit board on which the micro-LEDs with the color conversion layers are arranged may be resin-encapsulated.

[0040] <Fourth aspect of the present invention> A fourth aspect of the present invention is a color-converting optical sheet material for arranging a color-converting layer on a micro-LED using a laser lift-off method, which is preferably used in the manufacturing methods of the first, second, and third aspects of the present invention described above.

[0041] As shown in Figure 7A, the color-converting optical sheet material 70 has a light-transmitting sheet substrate 71 and a color-converting layer 72 disposed on one side thereof. The color-converting layer 72 is a mixture of quantum dot particles or phosphor particles dispersed in a curable resin composition that emit red fluorescence at a wavelength of 600 to 670 nm, green fluorescence at a wavelength of 500 to 570 nm, or white fluorescence at a wavelength of 430 to 670 nm when irradiated with blue laser light with a wavelength of 430 to 500 nm. Alternatively, the mixture is a mixture of quantum dot particles or phosphor particles dispersed in a curable resin composition that emit red fluorescence at a wavelength of 600 to 670 nm, green fluorescence at a wavelength of 500 to 570 nm, blue fluorescence at a wavelength of 430 to 500 nm, or white fluorescence at a wavelength of 430 to 670 nm when irradiated with ultraviolet laser light with a wavelength of 300 to 400 nm.

[0042] The light-transmitting sheet substrate 71 constituting the color-converting optical sheet material 70 functions as a release substrate that holds the color-converting layer 72 when the color-converting optical sheet material 70 is stored, but releases the color-converting layer 72 when laser lift-off occurs. The material of such a light-transmitting sheet substrate 71 is preferably a material that transmits 30% or more of light with a wavelength of 200 to 400 nm, and examples include quartz glass, glass, silicate glass, acrylic resin, polycarbonate resin, etc. The thickness of such a light-transmitting sheet substrate 71 is preferably 100 to 1000 μm, more preferably 300 to 700 μm.

[0043] The color conversion layer 72 may be formed as individual pieces on the entire surface of one side of the light-transmitting sheet substrate 71, as shown in Figure 7A, or it may be formed in layers over a wide area, as shown in Figure 7B. The color conversion optical sheet material 70 in Figure 7A can be created by removing the color conversion layer 72 of the color conversion optical sheet material 70 in Figure 7B, except for the parts that should remain as individual pieces, by laser irradiation using the laser lift-off method. Laser lift-off conditions such as laser wavelength, laser power, and laser irradiation time can be appropriately determined according to the size of the laser irradiation target and the type of constituent material.

[0044] The thickness of the color conversion layer 72 is preferably 2 to 30 μm, and more preferably 4 to 20 μm.

[0045] Known quantum dot particles or phosphor particles can be used as the components of the color conversion layer 72. Both can be used in combination.

[0046] In this invention, quantum dot particles are wavelength-converting materials that absorb light of one wavelength and emit light of another wavelength. Because they are sufficiently small in size (less than tens of nanometers), their electrical and optical properties differ from those of bulk materials due to the quantum confinement effect. For example, the emission properties of quantum dot particles are more closely related to their size and shape than to their composition. The fluorescence of quantum dot particles is based on the emission of lower energy in the form of photons when valence electrons are excited by absorbing a specific wavelength, and then these excited electrons return to the ground state. The quantum confinement effect changes the energy difference between the valence atoms and the conduction band based on the size and shape of the quantum dot particle, meaning that the energy and wavelength of the emitted photons depend on the size and shape of the quantum dot particle. This means that the larger the quantum dot particle, the lower the energy of its fluorescence spectrum. Therefore, smaller quantum dot particles emit bluer light (higher energy), and larger quantum dots emit redder light (lower energy). This allows for the adjustment of the size dependence of semiconductor photoluminescence emission wavelengths across the entire visible spectrum, resulting in a clear emission spectrum and high quantum efficiency.

[0047] Examples of quantum dot particles, though not limited to them, include Group II-VI, Group III-V, and Group IV-VI semiconductor materials. For example, compound semiconductor materials include CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, GaAs, GaP, GaAs, GaSb, HgS, HgSe, HgTe, InAs, InP, InSb, AlAs, AlP, and AlSb. Alloy semiconductor materials include InGaP, ZnSeTe, ZnCdS, ZnCdSe, and CdSeS.

[0048] In the present invention, phosphor particles are particles that exhibit luminescence due to their composition. For example, sulfides, aluminates, oxides, silicates, nitrides, YAG (optionally doped with cerium), and terbium aluminum garnet (TAG)-based materials can be mentioned. Specifically, the following phosphors are exemplified.

[0049] Yellow-green emitting phosphors: (Ca,Sr,Ba)Al2O4:Eu (green), (Lu,Y)3Al5O 2+ , x :Ce 3+ (LuAG,YAG) (yellow-green), Tb3Al5O 12 :Ce 3+ (TAG) (yellow-green); Orange-red emitting phosphors: BaMgAl 10 O 17 :Eu: 2+ (Mn 2+ )、Ca2Si5N8:Eu 2+ (orange-red), (Zn,Mg)S:Mn (green, red), (Ca,Sr,Ba)S:Eu: 2+ (red); Uv-cyan absorbing phosphors for blue and yellow-green emission: (Mg,Ca,Sr,Ba)2SiO4:Eu 2+ (uv-blue excitation, yellow emission), (Mg,Ca,Sr,Ba)3Si2O7:Eu 2+ (uv-cyan excitation, blue-green emission), Ca8Mg(SiO4)4Cl2:Eu 2+ (uv-cyan excitation, blue emission); and Phosphors capable of emitting over the entire visible spectrum depending on composition and treatment: (Sr,Ca,Ba)Si x O y N z :Eu 2+ (y>0 green, y = 0 red), Y2O2S:Eu <00,00018>(blue-green), (Ca,Mg,Y) v Si W Al x O y N z :Eu 2 (yellow-green-red).

[0050] The particle size of these phosphor particles is preferably 1 μm to 20 μm, but can also be 100 nm to 1 μm. The phosphor particles can also be a blend of 1 μm to 20 μm particles and 100 nm to 1 μm nanoparticles. Here, the nanoparticles can help reduce the amount of sedimentation when dispersed within the matrix material of the wavelength conversion layer, for example, before curing or solvent removal, which enables a more uniform distribution of nanoparticles and emission from the light-emitting device.

[0051] Furthermore, the color conversion layer 72 may contain light scattering agents such as TiO2 or Al2O3 particles. The light scattering agent can increase the scattered light within the color conversion layer, thereby increasing the luminescence efficiency of the phosphor particles and reducing the blurring of light emitted from the color conversion layer.

[0052] The color conversion layer 72 may further contain a pigment or dye. This allows for color correction of the light emitted from the color conversion layer. As such a pigment or dye, one having a color similar to the emission wavelength of the phosphor particles can be used. Examples include lysol rubin (red), β-copper thalocyanine (blue), and diaryllide yellow (yellow).

[0053] Preferably, a known thermosetting or photocurable resin composition can be used as the curable resin composition constituting the color conversion layer 72. From the viewpoint of stability and reliability over time, it is preferable to use a thermosetting resin composition. Such a curable resin composition preferably exhibits excellent cushioning (shock absorption) so that the color conversion layer 72 can be transferred to the microLED well. This suppresses the occurrence of defects such as displacement, deformation, breakage, and detachment of chip components, and improves the transfer rate of chip components by laser irradiation. Such cushioning can be evaluated by durometer A hardness and / or storage modulus, as described later.

[0054] The durometer A hardness of the color conversion layer 72 is preferably 20 to 40, more preferably 20 to 35, and particularly preferably 20 to 30. If the durometer A hardness is too high, the color conversion layer is too hard, which tends to cause defects such as deformation and breakage of the chip component. If the durometer A hardness is too low, the color conversion layer is too soft, which tends to cause defects such as displacement of the chip component. The durometer A hardness of the color conversion layer can be measured in accordance with JIS K6253, using a durometer A measuring device (Polymer Instruments Co., Ltd.) to measure rubber hardness (Japanese Industrial Standard JIS-A hardness).

[0055] The storage modulus of the color conversion layer 72 is preferably 60 MPa or less, more preferably 30 MPa or less, and particularly preferably 10 MPa or less. If the storage modulus is too high, it cannot absorb the impact of the chip component ejected at high speed by laser irradiation, and the transfer rate of the chip component tends to decrease. The storage modulus can be determined by a dynamic viscoelasticity test using an indentation test device (temperature 30°C, frequency 200 Hz, using a flat punch with a diameter of 100 μm, target indentation depth of 1 μm, sweeping in the frequency range of 1 to 200 Hz).

[0056] Furthermore, the storage modulus (at 30°C) of the color conversion layer 72 after curing, measured in tensile mode according to JIS K7244, is preferably 100 MPa or higher, and more preferably 2000 MPa or higher. If the storage modulus at 30°C is too low, there is a concern that the connection reliability may decrease.

[0057] The thermosetting resin composition constituting the color conversion layer 72 contains a rubber component, a film-forming resin, a thermosetting resin, a thermosetting agent, and quantum dot particles or phosphor particles. If necessary, other known additives may be included, to the extent that they do not impair the effects of the invention. The content of quantum dot particles or phosphor particles is preferably 1 to 20 parts by mass, more preferably 2 to 10 parts by mass, per 100 parts by mass of the total of the rubber component, film-forming resin, thermosetting resin, thermosetting agent, and quantum dot particles or phosphor particles.

[0058] (Rubber component) The rubber component contained in the thermosetting resin composition is a component for imparting cushioning (shock absorption) to the color conversion layer, and is not particularly limited as long as it is an elastomer with good cushioning properties. Specific examples include acrylic rubber, silicone rubber, butadiene rubber, and polyurethane resin (polyurethane elastomer). Among these, it is preferable to have one or more selected from acrylic rubber and silicone rubber. The content of the rubber component is preferably 1 to 20 parts by mass, more preferably 2 to 10 parts by mass, per 100 parts by mass of the total of the rubber component, film-forming resin, thermosetting resin, thermosetting agent, and quantum dot particles or phosphor particles.

[0059] (film-forming resin) As film-forming resins, from the viewpoint of film-forming properties, various resins such as phenoxy resins, polyester resins, polyurethane resins, polyester urethane resins, acrylic resins, polyimide resins, and butyral resins, with a weight-average molecular weight of about 10,000 to 80,000, are preferably used. These may be used individually or in combination of two or more types. Among these, phenoxy resin is preferred from the viewpoint of film formation state and connection reliability. The content of the film-forming resin is preferably 20 to 50 parts by mass, more preferably 25 to 45 parts by mass, and even more preferably 35 to 45 parts by mass, per 100 parts by mass of the total of the rubber component, film-forming resin, thermosetting resin, thermosetting agent, and quantum dot particles or phosphor particles.

[0060] (thermosetting resin) Examples of thermosetting resins include epoxy compounds and (meth)acrylate compounds, with epoxy compounds being particularly preferred. These compounds may be monomers, oligomers, or polymers. The content of the thermosetting resin is preferably 10 to 50 parts by mass, more preferably 20 to 40 parts by mass, and even more preferably 25 to 35 parts by mass, based on 100 parts by mass of the total of the rubber component, film-forming resin, thermosetting resin, thermosetting agent, and quantum dot particles or phosphor particles.

[0061] The epoxy compound that can be used as a thermosetting resin is not particularly limited as long as it has one or more epoxy groups in its molecule. For example, it may be a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, or a urethane-modified epoxy resin. Among these, a high-purity bisphenol A type epoxy resin is preferably used. A specific example of a high-purity bisphenol A type epoxy resin is the product name "YL980" manufactured by Mitsubishi Chemical Corporation. When using an epoxy compound as a thermosetting resin, the epoxy compound content is preferably 30 to 60 parts by mass, more preferably 35 to 55 parts by mass, and even more preferably 35 to 45 parts by mass, per 100 parts by mass of the total of the rubber component, film-forming resin, thermosetting resin, thermosetting agent, and quantum dot particles or phosphor particles.

[0062] (Thermosetting agent) The thermosetting agent is selected according to the thermosetting resin. For example, if the thermosetting resin is an epoxy compound, a thermal anionic polymerization initiator or a thermal cationic polymerization initiator can be preferably selected, and a thermal cationic polymerization initiator that suppresses the curing reaction by laser light and allows for rapid curing by heat can be more preferably selected. The content of the thermosetting agent can be determined according to the type of thermosetting agent and the type of thermosetting resin. The content of the thermosetting agent is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, and even more preferably 3 to 6 parts by mass, per 100 parts by mass of the total of the rubber component, film-forming resin, thermosetting resin, thermosetting agent and quantum dot particles or phosphor particles.

[0063] Furthermore, suitable thermal cationic polymerization initiators for epoxy compounds are those that generate an acid capable of cationic polymerization of cationic polymer-type compounds upon heating, and known iodonium salts, sulfonium salts, phosphonium salts, ferrocenes, etc., can be used. Among these, aromatic sulfonium salts, which exhibit good latent properties with respect to temperature, can be preferably used. A specific example of an aromatic sulfonium salt-based polymerization initiator is, for example, the product name "San-Aid SI-60L" manufactured by Sanshin Chemical Industry Co., Ltd. The content of such thermal cationic polymerization initiator is preferably 1 to 15 parts by mass, more preferably 1 to 10 parts by mass, and even more preferably 3 to 8 parts by mass, per 100 parts by mass of the total of the rubber component, film-forming resin, thermosetting resin, thermosetting agent, and quantum dot particles or phosphor particles.

[0064] (Inorganic filler) In addition, inorganic fillers may be used in the thermosetting resin composition as needed to adjust the durometer A hardness of the color conversion layer, the storage modulus at a frequency of 200 Hz, and the storage modulus after curing. These may include silica, talc, titanium dioxide, calcium carbonate, magnesium oxide, silane coupling agents, diluent monomers, fillers, softeners, colorants, flame retardants, thixotropic agents, etc. The inorganic fillers may be used alone or in combination of two or more types.

[0065] The color-converting optical sheet material 70 of the present invention, as described above, preferably has a tack force of 0.1 MPa or more, more preferably 0.5 MPa or more, according to JIS Z0237, so that the color-converting layer 72 can be stably temporarily fixed (temporarily secured) when transferred to the micro-LED 1 during laser lift-off. There is no particular upper limit to the tack force as long as the color-converting layer 72 can be separated from the light-transmitting sheet substrate 71 during laser lift-off, but it is preferably 6.0 MPa or less, more preferably 5.0 MPa or less. The tack force can be controlled by adjusting the type and amount of constituent materials of the color-converting layer, but it can also be controlled by adjusting the drying conditions of the color-converting layer (drying temperature, drying time, amount of residual solvent, etc.).

[0066] <<Fifth aspect>> A fifth aspect of the present invention provides an optical device equipped with a microLED device, such as a full-color display panel or a white light source panel, on which a color conversion layer of the color conversion optical sheet material of the fourth aspect of the present invention is disposed on the surface. Examples of such optical devices include mobile phones, personal computers, television sets, VR devices, and full-color display panels for monitors. These optical devices are manufactured so that each pixel of the microLED device has a color conversion layer on two or three of the three monochromatic microLED subpixels, thus allowing the color conversion layer to be provided without the problems associated with conventional photolithography, screen printing, or inkjet methods. [Examples]

[0067] The present invention will be described in detail below with reference to examples.

[0068] Example 1 <Color conversion optical sheet material for converting blue micro-LED light emission into white light> A resin paste was obtained by uniformly mixing 70 parts by mass of toluene and 30 parts by mass of hydrogenated styrene-ethylene-butylene-styrene block (hydrogenated SEBS) copolymer (Septon V9827, Kuraray Co., Ltd.). A composition for forming a white conversion layer was obtained by uniformly mixing 97 parts by mass of this resin paste with 3 parts by mass of the phosphor particles described later and 0.0022 parts by mass of the colorant described later. This composition was applied to a glass substrate to a dry thickness of 4 μm, and dried at 50°C for 40 seconds so that the residual toluene content was 10% by mass. This resulted in a color conversion optical sheet material in which a tacky white conversion layer was uniformly formed over the entire surface of one side of the glass substrate. The phosphor particles used were a mixture of green sulfide-based phosphor (SrGa2S4:Eu) and red sulfide-based phosphor (CaS:Eu) in a ratio of 44.1:55.9. Furthermore, tetra-t-butyl-tetraazaporphyrin vanadyl complex (manufactured by Yamamoto Chemical Co., Ltd., optical filter dye PD-320, absorption maximum: 595 nm) was used as a colorant. In addition, the tack force of the color conversion layer, according to JIS Z0237, was 2 MPa, which is significantly higher than 0.1 MPa.

[0069] Example 2 <Creating a Micro LED White Light Source Panel> First, an anisotropic conductive film (particle-aligned ACF with conductive particle diameter of 2.2 μm and thickness of 4 μm, Dexerials, Inc.) was temporarily attached to a glass circuit board with an Au wiring pattern formed on its surface. Then, 100 blue micro-LEDs (34 × 58 μm rectangular, monochromatic blue emission (440~475 nm), TGM-G3458A, TSLC Corp.) were arranged on top of it in a square array with a 400 μm pitch according to a conventional method to obtain a micro-LED array substrate.

[0070] Next, the white conversion layer of the color conversion optical sheet material prepared in Example 1 was placed facing the micro-LEDs on the micro-LED array substrate. The white conversion layer was then irradiated with a laser from the glass substrate side using the following laser lift-off method with the micro-LED array pattern, causing the white conversion layer to detach from the glass substrate in piece-like pieces and transfer by landing them directly on the micro-LEDs. This operation was performed on the remaining 99 micro-LEDs, and the number of micro-LEDs with properly transferred white conversion layers was confirmed using a metallurgical microscope. As a result, the rate of properly transferred layers was 98%. Subsequently, the white conversion layer was fully dried at 100°C for 60 seconds, and the remaining toluene was removed to fix the white conversion layer. This resulted in obtaining a micro-LED white light source panel in which the white conversion layer was transferred directly on the micro-LEDs.

[0071] Subsequently, a liquid encapsulant (Structbond, Mitsui Chemicals, Inc.) was supplied to the microLEDs of the obtained microLED white light source panel, and the microLEDs with the white conversion layer were resin-encapsulated by thermal aging treatment at 150°C.

[0072] (Laser lift-off method) Laser lift-off was performed using a laser lift-off device (MT-30C200, Shin-Etsu Chemical Co., Ltd.) under the following conditions.

[0073] Laser: Excimer laser with an oscillation wavelength of 248 nm Laser pulse energy: 600J Flux: 150 J / cm² 2 Pulse width (irradiation time): 30,000 picoseconds Pulse frequency: 0.01kHz Number of irradiation pulses: 1 pulse per color conversion layer sub-piece.

[0074] Pulse energy of the laser light that is imaged at the interface between the color conversion layer and the glass substrate: 0.001~2J Fluctuation: 0.001~2 J / cm 2 Pulse width (irradiation time): 0.01 to 1 × 10 9 picosecond Pulse frequency: 0.1~10000Hz Number of irradiation pulses: 1 to 30,000,000.

[0075] Mask used: A pattern was used in which a predetermined number of windows of a predetermined size were formed at a predetermined pitch so that the projection at the interface between the color conversion layer and the glass substrate would be an array of laser light measuring 34 μm vertically and 58 μm horizontally, with a vertical pitch of 400 μm horizontally.

[0076] Example 3 <Color conversion optical sheet material having individual white light conversion layers for converting the light emitted from blue micro-LEDs into white light> A white conversion layer-forming composition identical to that prepared in Example 1 was prepared. This white conversion layer-forming composition was applied to one side of a glass substrate and dried at 50°C for 40 seconds to form a 4 μm thick white conversion layer with tackiness, resulting in a residual toluene content of 10% by mass. Next, laser irradiation was performed from the glass substrate side, in accordance with the laser lift-off method performed in Example 2, so that 100 individual white conversion layers (34 × 58 μm rectangles) remained in a 400 μm pitch square array, thereby obtaining a color conversion optical sheet material having numerous individual white conversion layers on one side of the glass substrate. The tackiness of this white conversion layer, according to JIS Z0237, was 2 MPa, significantly exceeding 0.1 MPa.

[0077] Example 4 <Creating a Micro LED White Light Source Panel> First, similar to Example 2, an anisotropic conductive film was temporarily attached to a glass circuit board, and then 100 blue micro-LEDs (34 × 58 μm rectangular, monochromatic blue light emission (440~475 nm), TGM-G3458A, TSLC Corp.) were arranged on top of it in a square array with a 400 μm pitch according to a conventional method to create a micro-LED array substrate.

[0078] Next, the individual white conversion layers of the color conversion optical sheet material prepared in Example 3 were placed facing a micro-LED array substrate. The individual white conversion layers were irradiated with a laser from the glass substrate side under the same conditions as in Example 2, following the laser lift-off method. The individual white conversion layers were detached from the glass substrate and transferred by landing directly on the micro-LEDs. This operation was performed on the remaining 99 micro-LEDs in the same manner as in Example 2, and the number of micro-LEDs with properly transferred white conversion layers was confirmed using a metallurgical microscope. As a result, the rate of properly transferred layers was 98%. Subsequently, the white conversion layers were fully dried at 100°C for 60 seconds, and the remaining toluene was removed to fix the white conversion layers. This resulted in a micro-LED white light source panel in which the white conversion layers were transferred directly on the micro-LEDs.

[0079] Subsequently, a liquid encapsulant (Structbond, Mitsui Chemicals, Inc.) was supplied to the microLEDs of the obtained microLED white light source panel, and the microLEDs with the white conversion layer were resin-encapsulated by thermal aging treatment at 150°C.

[0080] Examples 5-7 <Adjusting the tackiness of color-converting optical sheet materials> A white conversion layer-forming composition identical to that prepared in Example 1 was prepared. Using this white conversion layer-forming composition, in the same manner as in Example 3, 100 individual composition layers (35 × 60 μm rectangles with a dry thickness of 4 μm) were formed on one side of a glass substrate in a 400 μm pitch square array. The layers were dried at 50°C for 60 seconds (Example 5), 20% (Example 6), and 10 seconds (Example 7), respectively, so that the residual toluene content was 5% by mass (Example 5), 20% by mass (Example 6), and 30% by mass (Example 7), thereby forming tacky individual white conversion layers. As a result, color conversion optical sheet materials having numerous individual white conversion layers on one side of the glass substrate were obtained. Furthermore, the tack force of the white conversion layer according to JIS Z0237 was 0.5 MPa (Example 5), 5.0 MPa (Example 6), and 6.0 MPa (Example 7), respectively, exceeding 0.1 MPa. Therefore, from the results of Examples 5 to 7, it was found that the tack force of the color-converting optical sheet material can be controlled by the drying conditions of the white-converting layer-forming composition. [Industrial applicability]

[0081] In the manufacturing method of the micro-LED device of the present invention, when forming a color conversion layer directly on a monochromatic or ultraviolet micro-LED, a laser lift-off method is used with a color conversion optical sheet material in which a color conversion layer is formed on a light-transmitting sheet substrate. Therefore, the thickness of the color conversion layer can be easily controlled, a color conversion layer can be formed on the surface of a very small micro-LED, and unlike when using the inkjet method, the burden of controlling the viscosity of the composition for forming the color conversion layer is reduced, increasing the degree of freedom of the constituent materials of the color conversion layer. Furthermore, mass transfer processing of the micro-LED in a short time is facilitated. In addition, the need to consider the transfer properties between the micro-LED and the color conversion layer is reduced, and the control of the peeling balance is also made easier. Moreover, even if a black matrix is ​​formed around the pixels, the color conversion layer can be easily detached from the color conversion optical film and easily transferred to the LED. Therefore, the manufacturing method of the present invention is useful as a manufacturing method for micro-LED devices. [Explanation of Symbols]

[0082] 1 Micro LED 2 microLED wafers 3, 41, 51 Circuit boards 4, 21, 71 Light-transmitting sheet substrate 5 Anisotropic conductive film 20, 70 color conversion optical sheet material 20R Red Conversion Optical Sheet Material 20G Green Conversion Optical Sheet Material 20B Blue Conversion Optical Sheet Material 22, 72 color conversion layer 22R Red Conversion Layer 22G Green Conversion Layer 22B Blue Conversion Layer 40a, 40b, 40c Blue Micro LEDs 50a, 50b, 50c UV MicroLEDs L laser light

Claims

1. A method for manufacturing a microLED device in which a color conversion layer is placed directly above a microLED placed on a circuit board, comprising the following steps (a), (b), and (c): Process (a) The process of placing micro LEDs on a circuit board; Process (b) A step of facing the color conversion layer of a color conversion optical sheet material, which has a color conversion layer formed on one side of a light-transmitting sheet substrate, towards a micro-LED placed on a circuit board; and Process (c) A process in which the color conversion layer of a color conversion optical sheet material is irradiated with laser light from the light-transmitting sheet substrate side, thereby transferring the color conversion layer in the area irradiated with laser light onto a micro-LED. A method for manufacturing a microLED device, characterized by having the following features.

2. The manufacturing method according to claim 1, wherein in step (c), when transferring the color conversion layer in the portion irradiated with laser light onto the micro-LED, individual pieces of the color conversion layer are transferred.

3. The manufacturing method according to claim 1 or 2, wherein in step (a), the arrangement of microLEDs on the circuit board is performed by bonding an LED wafer on which a plurality of microLEDs are formed to the circuit board.

4. The manufacturing method according to claim 1 or 2, wherein in step (a), the arrangement of microLEDs on the circuit board is performed by irradiating the microLEDs, which are arranged on one side of the light-transmitting sheet substrate, with laser light from the light-transmitting sheet substrate side, thereby transferring the irradiated microLEDs to the circuit board.

5. The manufacturing method according to claim 1 or 2, wherein, prior to step (a), a conductive film for electrically connecting the circuit board and the micro LED is placed in individual pieces at predetermined positions in the circuit wiring where the micro LED is to be arranged.

6. A method for manufacturing a microLED device in which one pixel of the microLED device comprises three blue microLEDs as subpixels, a red conversion layer is formed directly above one of the three blue microLEDs, a green conversion layer is formed directly above another blue microLED, and no color conversion layer is formed directly above the remaining blue microLED, the method comprising the following steps (A), (B), and (C): Process (A) The process of placing blue micro-LEDs on a circuit board; Process (B) A step of facing one of the three blue microLEDs constituting one pixel of a microLED device with the red conversion layer of a red conversion optical sheet material, which has a red conversion layer formed on one side of a light-transmitting sheet substrate, toward one of the blue microLEDs, and facing the green conversion layer of a green conversion optical sheet material, which has a green conversion layer formed on one side of a light-transmitting sheet substrate, toward another blue LED; and Process (C) A process in which the red conversion layer of a red conversion optical sheet material and the green conversion layer of a green conversion optical sheet material are irradiated with laser light from the light-transmitting sheet substrate side using a laser lift-off method, thereby transferring the red conversion layer and green conversion layer in the irradiated area onto a blue micro-LED. A method for manufacturing a microLED device, characterized by having the following features.

7. A method for manufacturing a microLED device in which one pixel of the microLED device comprises three ultraviolet microLEDs as subpixels, a red conversion layer is formed directly above one of the three ultraviolet microLEDs, a green conversion layer is formed directly above another ultraviolet microLED, and a blue conversion layer is formed directly above the remaining ultraviolet microLED, the method comprising the following steps (AA), (BB), and (CC): Process (AA) The process of placing ultraviolet micro-LEDs on a circuit board; Process (BB) A step of facing one of the three ultraviolet microLEDs constituting one pixel of a microLED device with the red conversion layer of a red conversion optical sheet material having a red conversion layer formed on one side of a light-transmitting sheet substrate, facing another ultraviolet microLED with the green conversion layer of a green conversion optical sheet material having a green conversion layer formed on one side of a light-transmitting sheet substrate, and facing the remaining ultraviolet microLED with the blue conversion layer of a blue conversion optical sheet material having a blue conversion layer formed on one side of a light-transmitting sheet substrate; and Process (CC) A process in which, by irradiating the red conversion layer of a red conversion optical sheet material, the green conversion layer of a green conversion optical sheet material, and the blue conversion layer of a blue conversion optical sheet material with laser light from the light-transmitting sheet substrate side using a laser lift-off method, the red conversion layer, green conversion layer, and blue conversion layer in the areas irradiated with laser light are transferred directly onto an ultraviolet micro-LED. A method for manufacturing a microLED device, characterized by having the following features.

8. A color conversion optical sheet material for arranging a color conversion layer on a microLED using the laser lift-off method, It comprises a light-transmitting sheet substrate and a color conversion layer disposed on one side thereof. The color conversion layer is a curable resin composition in which phosphor particles or quantum dot particles that emit red, green, or white fluorescence upon irradiation with blue laser light, or phosphor particles or quantum dot particles that emit red, green, blue, or white fluorescence upon irradiation with ultraviolet laser light, are dispersed, and the tack force according to JIS Z0237 is 0.1 MPa or more. Color-converting optical sheet material.

9. The color-converting optical sheet material according to claim 8, wherein individual pieces of the color-converting layer are arranged on one side of a light-transmitting sheet substrate.

10. An optical device comprising a microLED device having a color conversion layer of the color conversion optical sheet material according to claim 8 or 9 disposed on its surface.

11. The optical device according to claim 10, used as a full-color display device or white light source panel for a mobile phone, personal computer, television set, VR device or monitor.

Images