Transfer method of micro light-emitting diode chip

Abstract

The present application discloses a method for transferring a micro light-emitting diode chip, comprising: bonding the micro light-emitting diode chip to a light-transmitting transition substrate by using a photosensitive adhesive layer, the micro light-emitting diode chip including a first connection electrode, the first connection electrode of the micro light-emitting diode chip being located on a side of the micro light-emitting diode chip away from the photosensitive adhesive layer, and the photosensitive adhesive layer including a soldering flux; providing a driving substrate including a plurality of second connection electrodes; moving the transition substrate above the driving substrate, aligning the first connection electrode of the micro light-emitting diode chip with the second connection electrode, and a welding material being formed on the first connection electrode or / and the second connection electrode; irradiating the photosensitive adhesive layer with a first laser to cause the micro light-emitting diode chip to fall off from the photosensitive adhesive layer and to volatilize the soldering flux; and irradiating with a second laser to melt the welding material, and the melted welding material connects the first connection electrode and the second connection electrode under the action of the volatilized soldering flux.

Description

Technical Field

[0001] This application relates to the field of display technology, and particularly to a method for transferring micro light-emitting diode chips. Background Art

[0002] Micro light-emitting diodes (Micro LEDs) have the advantages of high brightness, high luminous efficiency, and low power consumption, and thus have become a research hotspot in the current display technology field.

[0003] However, there is a problem of low transfer yield in the manufacturing process of micro light-emitting diode light-emitting substrates. How to improve the transfer yield of micro light-emitting diodes is a technical problem that needs to be solved. Summary of the Invention

[0004] The purpose of this application is to provide a method for transferring micro light-emitting diode chips to improve the transfer yield of micro light-emitting diode chips.

[0005] To achieve the above purpose, the technical solution is as follows:

[0006] A method for transferring micro light-emitting diode chips, the method comprising:

[0007] Bonding a micro light-emitting diode chip to a light-transmitting transition substrate using a photosensitive adhesive layer, the micro light-emitting diode chip including a first connection electrode, and the first connection electrode of the micro light-emitting diode chip being located on a side of the micro light-emitting diode chip away from the photosensitive adhesive layer, and the photosensitive adhesive layer including a soldering flux;

[0008] Providing a driving substrate, the driving substrate including a plurality of second connection electrodes;

[0009] Moving the transition substrate above the driving substrate, and aligning the first connection electrode of the micro light-emitting diode chip with the second connection electrode, and a welding material is formed on the first connection electrode or / and the second connection electrode;

[0010] Irradiating the photosensitive adhesive layer on the transition substrate with a first laser to cause the micro light-emitting diode chip to fall off from the photosensitive adhesive layer and to volatilize the soldering flux;

[0011] Irradiating with a second laser to melt the welding material, and the molten welding material connects the first connection electrode and the second connection electrode under the action of the volatilized soldering flux.

[0012] In the above method for transferring micro light-emitting diode chips, the wavelength of the first laser is the same as the wavelength of the second laser.

[0013] In the above method for transferring a micro light-emitting diode chip, the wavelength of the first laser is greater than or equal to 340 nanometers and less than or equal to 360 nanometers.

[0014] In the above method for transferring a micro light-emitting diode chip, the wavelength of the first laser is different from the wavelength of the second laser.

[0015] In the above method for transferring a micro light-emitting diode chip, a soldering material is formed on the first connection electrode.

[0016] In the above method for transferring a micro light-emitting diode chip, the soldering material is selected from at least one of Au, Al, Cu, Sn, In, and Ti.

[0017] In the above method for transferring a micro light-emitting diode chip, the soldering material is In or an In alloy.

[0018] In the above method for transferring a micro light-emitting diode chip, the viscosity of the photosensitive adhesive layer after being irradiated by the first laser is less than the viscosity of the photosensitive adhesive layer before being irradiated by the first laser.

[0019] In the above method for transferring a micro light-emitting diode chip, the preparation material of the photosensitive adhesive layer includes one of polyimide-based adhesives, acrylate-based adhesives, and silicone adhesives.

[0020] In the above method for transferring a micro light-emitting diode chip, the transition substrate is selected from one of a quartz glass substrate, a sapphire substrate, and a silicon substrate.

[0021] Beneficial effects: The present application provides a method for transferring a micro light-emitting diode chip. By irradiating the photosensitive adhesive layer on the transition substrate with the first laser, the micro light-emitting diode chip is detached from the photosensitive adhesive layer and the flux is volatilized. Then, the second laser is used for irradiation to melt the soldering material. Under the action of the volatilized flux, the molten soldering material connects the first connection electrode and the second connection electrode, so that the first connection electrode of the micro light-emitting diode chip can be better fixed to the second connection electrode of the driving substrate through the soldering material, improving the tensile strength between the first connection electrode and the second connection electrode, and further improving the transfer yield of the micro light-emitting diode chip. Moreover, the first laser irradiation and the second laser irradiation can be realized on the same machine platform, which is beneficial to simplifying the transfer process of the micro light-emitting diode chip while reducing the movement process of the micro light-emitting diode chip, thereby avoiding the movement of the micro light-emitting diode chip during the movement process, and improving the transfer processing accuracy of the micro light-emitting diode chip. Description of the Drawings

[0022] Figure 1 It is a schematic flow chart of the method for transferring a micro light-emitting diode chip according to an embodiment of the present application;

[0023] Figures 2A - 2G It is a process schematic diagram of the transfer method of the micro light-emitting diode chip according to an embodiment of the present application;

[0024] Figure 3 It is a flow schematic diagram of the transfer method of the micro light-emitting diode chip according to another embodiment of the present application. Detailed implementation manners

[0025] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application.

[0026] Please refer to Figure 1 , which is a flow schematic diagram of the transfer method of the micro light-emitting diode chip according to an embodiment of the present application. The transfer method of the micro light-emitting diode chip includes the following steps:

[0027] S101: Bond the micro light-emitting diode chip to the light-transmitting transition substrate by using a photosensitive adhesive layer. The micro light-emitting diode chip includes a first connection electrode, and a welding material is formed on the first connection electrode. The first connection electrode of the micro light-emitting diode chip is located on the side of the micro light-emitting diode chip away from the photosensitive adhesive layer. The photosensitive adhesive layer includes a soldering flux.

[0028] As Figure 2A shown, the micro light-emitting diode chip 13 includes a chip body 131, a first connection electrode 132, and a welding material 133. The first connection electrode 132 is connected to the chip body 131, and the welding material 133 is formed on the first connection electrode 132. Among them, the chip body 131 includes a red light micro light-emitting diode, a blue light micro light-emitting diode, and a green light micro light-emitting diode. It can be understood that the chip body 131 may also only include one of the red light micro light-emitting diode, the blue light micro light-emitting diode, and the green light micro light-emitting diode.

[0029] Specifically, after the chip body 131 and the first connection electrode 132 are prepared on the substrate by using semiconductor processes, the welding material 133 is formed on the first connection electrode 132 by evaporation or electroplating, and then the micro light-emitting diode chip 13 is peeled off from the substrate. The photosensitive adhesive layer 11 is formed on the light-transmitting transition substrate 10 by coating or laminating. The light-emitting surface of the peeled micro light-emitting diode chip 13 is attached to the photosensitive adhesive layer 11, so that the micro light-emitting diode chip 13 is bonded to the transition substrate 10, and the first connection electrode 132 is located on the side of the micro light-emitting diode chip 13 away from the photosensitive adhesive layer 11, asFigure 2A as shown

[0030] The substrate can be any one of a sapphire substrate, a silicon substrate, or a gallium nitride substrate.

[0031] The transition substrate 10 is not the same substrate as the substrate. The transition substrate 10 is selected from one of a quartz glass substrate, a sapphire substrate, or a silicon substrate, so that the transition substrate 10 has light transmissivity.

[0032] The photosensitive adhesive layer 11 has light transmissivity. The viscosity of the photosensitive adhesive layer 11 decreases under the irradiation of the first laser L1 hereinafter, but it will not decompose. The preparation materials of the photosensitive adhesive layer 11 include one of polyimide-based adhesives, acrylate-based adhesives, and silicone adhesives.

[0033] The photosensitive adhesive layer 11 includes a soldering flux 12. The soldering flux 12 can help and promote the soldering process in the soldering process, and at the same time has a protective effect and prevents oxidation reactions. The soldering flux 12 includes activators such as rosin.

[0034] The welding material 133 is selected from at least one of Au, Al, Cu, Sn, In, and Ti. Specifically, the welding material 133 is In or an In alloy, so that the power density required to melt the welding material 133 by the second laser L2 hereinafter is relatively low, reducing the adverse effects of the second laser L2 on the micro light-emitting diode chip 13.

[0035] S102: Provide a driving substrate, and the driving substrate includes a plurality of second connection electrodes.

[0036] The driving substrate 20 includes a carrier plate 201, a thin film transistor array layer 202, and a plurality of second connection electrodes 203. The thin film transistor array layer 202 is disposed on the carrier plate 201, and the plurality of second connection electrodes 203 are disposed on the thin film transistor array layer 202, as Figure 2B shown

[0037] Among them, the thin film transistor array layer 202 includes a plurality of thin film transistors arranged in an array, and the plurality of second connection electrodes 203 are electrically connected to the thin film transistors.

[0038] The carrier plate 201 can be a flexible substrate, such as a polyimide substrate. It can be understood that the carrier plate 201 can also be a glass substrate.

[0039] The preparation materials of the second connection electrode 203 include at least one of copper, aluminum, titanium, molybdenum, and silver.

[0040] S103: Move the transition substrate above the driving substrate, and align the first connection electrode of the micro light-emitting diode chip with the second connection electrode.

[0041] Specifically, in a sealed cavity, the driving substrate 20 is placed on a machine table, the transition substrate 10 is inverted, and the transition substrate 10 is moved directly above the driving substrate 20. An optical detection device is used to set the first connection electrodes 132 of the micro light-emitting diode chips 13 one-to-one with the second connection electrodes 203 on the driving substrate 20, and the soldering material 133 on the first connection electrodes 132 is brought into contact with the corresponding second connection electrodes 203, as Figure 2C shown.

[0042] S104: Use a first laser to irradiate the photosensitive adhesive layer on the transition substrate, so that the micro light-emitting diode chips fall off from the photosensitive adhesive layer and the flux volatilizes.

[0043] Specifically, a laser emission device M is installed on the machine table in the sealed cavity. The first laser L1 emitted by the laser emission device M is incident on the transition substrate 10 from the back side of the surface of the transition substrate 10 provided with the photosensitive adhesive layer 11, as Figure 2D shown.

[0044] The first laser L1 passes through the light-transmissive transition substrate 10 and irradiates the photosensitive adhesive layer 11. The photosensitive adhesive layer 11 undergoes a chemical reaction or the like under the heating action of the first laser L1, resulting in a decrease in viscosity. The gravity of the micro light-emitting diode chips 13 is greater than the adhesive force between the photosensitive adhesive layer 11 and the micro light-emitting diode chips 13, and the micro light-emitting diode chips 13 fall off from the photosensitive adhesive layer 11. Moreover, the flux 12 in the photosensitive adhesive layer 11 is heated and volatilized under the irradiation of the first laser L1. The volatilized flux 12 adheres to the second connection electrodes 203 and / or the soldering material 133, and the volatilized flux 12 may also diffuse into the air near the photosensitive adhesive layer 11 to provide a flux 12 atmosphere, as Figure 2E shown.

[0045] Among them, the first laser L1 can be any one of an extreme ultraviolet laser, an infrared laser, and an ultraviolet laser. Specifically, the first laser L1 is an ultraviolet laser, and the wavelength of the first laser L1 is greater than or equal to 340 nanometers and less than or equal to 360 nanometers, so that the first laser L1 has good penetrability in the transition substrate 10. For example, the wavelength of the first laser L1 is 345 nanometers, 348 nanometers, 350 nanometers, 352 nanometers, 355 nanometers.

[0046] It should be noted that the power density of the first laser L1 irradiating the photosensitive adhesive layer 11 needs to make the viscosity of the photosensitive adhesive layer 11 after being irradiated by the first laser L1 less than the viscosity of the photosensitive adhesive layer 11 before being irradiated by the first laser L1, and also needs to volatilize the flux 12, but cannot decompose the photosensitive adhesive layer 11 to avoid the particles formed after the decomposition of the photosensitive adhesive layer 11 affecting the subsequent soldering process.

[0047] S105: Use the second laser to irradiate so as to melt the welding material. Under the action of the volatilized soldering flux, the melted welding material connects the first connection electrode and the second connection electrode.

[0048] Wherein, the wavelength of the second laser L2 is the same as that of the first laser L1, so that the second laser L2 and the first laser L1 can be emitted by the same laser emitting device, avoiding the need to move the driving substrate 20 when the micro light emitting diode chip 13 falls off onto the driving substrate 20, thereby affecting the alignment accuracy between the first connection electrode 132 of the micro light emitting diode chip 13 and the second connection electrode 203 on the driving substrate 20.

[0049] Specifically, adjust the power density of the laser emitting device M. The laser emitting device M emits the second laser L2. The second laser L2 is incident from the back side of the surface of the transition substrate 10 provided with the photosensitive adhesive layer 11. The second laser L2 passes through the transition substrate 10 and irradiates the photosensitive adhesive layer 11, the micro light emitting diode chip 13, etc. The heat generated by the irradiation of the second laser L2 raises the temperature in the sealed cavity. The welding material 133 on the first connection electrode 132 melts under the action of the heat generated by the irradiation of the second laser L2. The melted welding material 133 is bonded to the first connection electrode 132 and the second connection electrode 203 under the promoting action of the volatilized soldering flux 12, as Figure 2F shown; remove the transition substrate 10, and the micro light emitting diode chip 13 is fixed on the driving substrate 20 to obtain the micro light emitting diode light emitting substrate 100, as Figure 2G shown.

[0050] It should be noted that when the heat generated by the irradiation of the second laser L2 melts the welding material 133, since the welding material 133 is In or an In alloy and the melting point of In or an In alloy is relatively low, reducing the power density of the second laser L2 can reduce the damage to the micro light emitting diode chip 13 when the second laser L2 irradiates the welding material 133 to melt it.

[0051] It can be understood that the wavelength of the first laser L1 and the wavelength of the second laser L2 can also be different. For example, the first laser L1 is an ultraviolet laser and the second laser L2 is an infrared laser. The first laser L1 and the second laser L2 are respectively emitted by two different laser emitting devices, but the two different laser emitting devices can be installed on the same machine table at the same time, and the two laser emitting devices switch to work to respectively emit the first laser L1 and the second laser L2.

[0052] The transfer method of the micro light-emitting diode in this embodiment irradiates the photosensitive resin layer on the transition substrate with a first laser, so that the micro light-emitting diode chip detaches from the photosensitive resin layer and the flux volatilizes. Then, a second laser is used for irradiation to melt the welding material. Under the action of the volatilized flux, the melted welding material connects the first connection electrode and the second connection electrode, enabling the first connection electrode of the micro light-emitting diode chip to be better fixed on the second connection electrode of the driving substrate through the welding material, improving the tensile strength between the first connection electrode and the second connection electrode, and further improving the transfer yield of the micro light-emitting diode chip. Moreover, the first laser irradiation and the second laser irradiation can be realized on the same machine platform, which is beneficial to simplifying the transfer process of the micro light-emitting diode chip while reducing the movement process of the micro light-emitting diode chip, thereby avoiding the movement of the micro light-emitting diode chip during the movement process and improving the transfer processing accuracy of the micro light-emitting diode chip.

[0053] Please refer to Figure 3 , which is a schematic flowchart of the transfer method of the micro light-emitting diode chip in another embodiment of the present application. Figure 3 The transfer method of the micro light-emitting diode chip shown is basically similar to Figure 1 the transfer method of the micro light-emitting diode chip shown. The difference is that Figure 3 step S201 in Figure 1 is different from step S101 in Figure 3 step S202 in Figure 1 is different from step S102 in

[0054] It should be noted that the welding material can be formed on the second connection electrode by means of stencil printing or the like.

[0055] In addition, the welding material 133 can also be formed on both the first connection electrode 132 and the second connection electrode 203 at the same time. The welding material 133 melts under the heating action of the second laser to connect the first connection electrode 132 and the second connection electrode 203.

[0056] The present application also provides a micro light-emitting diode array substrate, which is prepared by the transfer method of the micro light-emitting diode chip described above.

[0057] The description of the above embodiments is only used to help understand the technical solution and its core idea of the present application; those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for transferring a micro light-emitting diode chip, characterized in that, The method includes: Bonding a micro light-emitting diode chip to a light-transmitting transition substrate by using a photosensitive adhesive layer, where the micro light-emitting diode chip includes a first connection electrode, and the first connection electrode of the micro light-emitting diode chip is located on a side of the micro light-emitting diode chip away from the photosensitive adhesive layer, and the photosensitive adhesive layer includes a soldering flux; Providing a driving substrate, where the driving substrate includes a plurality of second connection electrodes; Moving the transition substrate above the driving substrate and aligning the first connection electrode of the micro light-emitting diode chip with the second connection electrodes, and a welding material is formed on the first connection electrode or / and the second connection electrodes; Irradiating the photosensitive adhesive layer on the transition substrate with a first laser to cause the micro light-emitting diode chip to fall off from the photosensitive adhesive layer and volatilize the soldering flux; Irradiating with a second laser to melt the welding material, and the melted welding material connects the first connection electrode and the second connection electrodes under the action of the volatilized soldering flux.

2. The method for transferring a micro light-emitting diode chip according to claim 1, characterized in that, The wavelength of the first laser is the same as the wavelength of the second laser.

3. The method for transferring a micro light-emitting diode chip according to claim 2, characterized in that, The wavelength of the first laser is greater than or equal to 340 nanometers and less than or equal to 360 nanometers.

4. The method for transferring a micro light-emitting diode chip according to claim 1, characterized in that, The wavelength of the first laser is different from the wavelength of the second laser.

5. The method for transferring a micro light-emitting diode chip according to claim 1, characterized in that, The welding material is selected from at least one of Au, Al, Cu, Sn, In, and Ti.

6. The method for transferring a micro light-emitting diode chip according to claim 1 or 5, characterized in that, The welding material is In or an In alloy.

7. The method for transferring a micro light-emitting diode chip according to claim 1, characterized in that, The viscosity of the photosensitive adhesive layer after being irradiated with the first laser is less than the viscosity of the photosensitive adhesive layer before being irradiated with the first laser.

8. The method for transferring a micro light-emitting diode chip according to claim 1 or 7, characterized in that, The preparation material of the photosensitive adhesive layer includes one of polyimide-based adhesives, acrylate-based adhesives, and silica gels.

9. The method for transferring a micro light-emitting diode chip according to claim 1, characterized in that, The transition substrate is selected from one of a quartz glass substrate, a sapphire substrate, and a silicon substrate.

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