A manufacturing method and self-assembly equipment of LED array device

Abstract

The present invention relates to a manufacturing method and self-assembly equipment of an LED array device, comprising the steps of: S1 providing a driving board, a plurality of pads being provided on the driving board, and a first metal being provided on the pads; S2 providing a large number of LED devices, a hydrophobic layer being provided on the light-emitting surface thereof, and a second metal being provided on the welding surface thereof; S3 applying a large number of LED devices to hot liquid, so that the LED devices float on the hot liquid with their light-emitting surfaces facing upward and welding surfaces facing downward, thereby forming an LED floating layer; S4 immersing the driving board into the hot liquid, so that the first metal melts in the hot liquid to form a liquid metal sticking point, and the liquid metal sticking point contacts and forms a bond with the second metal of the LED device; S5 removing the driving board from the hot liquid and cooling it, so that the liquid metal sticking point solidifies on the second metal to form a weld, thereby obtaining an LED array device. The present invention can not only greatly improve the manufacturing efficiency of the LED array device, but also effectively reduce the manufacturing difficulty and cost of the LED array device.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a manufacturing method and self-assembly equipment of an LED array device. Background Art

[0002] Applying third-generation semiconductors to displays is an important development direction of display technology. Among them, LED array devices that use semiconductor light-emitting devices LED as array units or pixels set on display driver boards have excellent display performance (high brightness, high contrast, high color gamut, wide viewing angle, fast response), low energy consumption, and long life. Whether it is used as a direct display or as a partition backlight for liquid crystal display, it is considered to be a more advanced display technology than traditional liquid crystal display and organic light-emitting display.

[0003] At present, such LED array devices generally include super-large LED curtain walls, and the array unit spacing can reach the centimeter level. Although the manufacturing difficulty is low, since each array unit needs to weld an LED lamp bead, the manufacturing efficiency is low and the cost is very high. Such LED array devices also include Mini-LED displays and Micro-LED displays. Mini-LED displays are LED array devices with array spacing at the millimeter level. At this stage, Mini-LED can be used as a direct display or as a partition backlight (local dimming) for liquid crystal displays. It generally adopts chip binding technology to bind LED chips one by one to the array unit position. Since a huge number of LED chips need to be bound, its manufacturing efficiency is also low and the cost is high. Micro-LED displays are LED array devices with array unit pitch below a millimeter. Due to the small pitch and huge number of array unit pitches, mass transfer technology is generally required to transfer the LED light emitters from the LED growth wafer (such as the epitaxial board used to grow LEDs) to the array unit positions of the display driver board. Currently, mass transfer technology is not yet mature. Although it can be transferred batch by batch through a transfer head, its efficiency is still low and the defect rate is high, which cannot meet the requirements of mass production.

[0004] Therefore, there is no efficient technology for manufacturing such LED array devices at present, and it is impossible to efficiently set a large number of LEDs to the array unit positions of the display driver board to reduce the manufacturing difficulty and cost of such displays. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a manufacturing method and self-assembly equipment for an LED array device, which can not only greatly improve the manufacturing efficiency of the LED array device and meet the requirements of mass production, but also effectively reduce the manufacturing difficulty and cost of the LED array device. The technical solution adopted is as follows:

[0006] A method for manufacturing an LED array device, characterized by comprising the following steps:

[0007] S1. Provide a driving board, wherein a plurality of pads constituting a pad array are arranged on a first board surface of the driving board, and a first metal is arranged on each pad;

[0008] S2. Provide a large number of LED devices, each of which has a light-emitting surface and a welding surface facing away from each other, wherein the light-emitting surface is provided with a hydrophobic layer, and the welding surface is provided with a second metal, the melting point of the second metal is higher than that of the first metal, and the second metal can be wetted by the molten first metal;

[0009] S3, applying a large number of LED devices to a hot liquid whose temperature reaches a first temperature zone, wherein the first temperature zone is a temperature interval higher than the melting point of the first metal; utilizing the hydrophobic layer of the LED device to repel the hot liquid, so that the LED device floats on the liquid surface of the hot liquid with its light-emitting surface facing upward and the welding surface facing downward, thereby forming an LED floating layer on the liquid surface of the hot liquid, wherein the LED floating layer has a bottom formed by the welding surface of the LED device;

[0010] S4, immersing the driving board into the hot liquid, so that the first metal on each pad on the driving board melts in the hot liquid to form liquid metal sticky points, and the first board surface of the driving board contacts the bottom of the LED floating layer, and each liquid metal sticky point contacts and forms adhesion with the second metal of the welding surface of the LED device corresponding to the bottom of the LED floating layer, and the bonded LED device is automatically aligned with the corresponding pad and corrected;

[0011] S5. Remove the driving board from the hot liquid and cool it to a second temperature zone, which is a temperature range lower than the melting point of the first metal, so that the liquid metal sticks and solidifies on the second metal to form a weld between the welding surface of the adhered LED device and the welding pad, thereby obtaining the LED array device.

[0012] The light-emitting surface of the LED device and the welding surface (P pole, N pole) are opposite to each other, and this LED device is generally called a vertical structure LED device. In order to obtain the desired light-emitting color, the semiconductor layer of the LED device can be selected from materials such as GaAs, GaP, SiC, GaN, etc. Generally, the LED devices are LED devices of the same light-emitting color or semiconductor material. For example, the LED device is preferably a GaN blue light LED, so that a certain color conversion layer (such as quantum dots, phosphor coating) can be added later to obtain color. The semiconductor layer (such as P-type layer, N-type layer, quantum well layer) of the LED device is generally grown on an epitaxial substrate (such as sapphire) by epitaxy (such as epitaxy by MOCVD), and finally peeled off from the epitaxial substrate by laser peeling and other processes. As a result, the LED device generally has a diaphragm structure, and its P pole and N pole are respectively located on two opposite surfaces of the device, one of which can be the above-mentioned light-emitting surface, and the other surface forms a welding surface by setting a second metal layer. Generally, the thickness of an LED device is within 20 μm. When the size of an LED device is larger (e.g., ≥100 μm), the electrode on its non-light-emitting surface can also be bonded to a thicker (e.g., ≥50 μm) supporting conductor layer, such as a conductive silicon layer or a metal layer, and the outer side of the supporting conductor layer is the welding surface of the LED device.

[0013] In the above manufacturing method, in step S3, in order to make the LED device float on the surface of the hot liquid, generally, hot liquid can be prepared first, and then a large number of LED devices can be added to the hot liquid. During the addition of the LED devices, the hydrophobic layer of the LED device repels the hot liquid and makes the LED device float on the surface of the hot liquid to form an LED floating layer. For some LED devices that sink into the hot liquid, bubbles or ultrasonic waves can be introduced into the hot liquid to make the hydrophobic layer adhere to the bubbles and float to the liquid surface, thereby making these LED devices float on the surface of the hot liquid in a directional manner with the light-emitting surface facing upward and the welding surface facing downward; in step S4, by making each liquid metal sticking point on the first plate body surface of the driving board contact with the bottom of the LED floating layer, at the corresponding position of the soldering pad, when the soldering surface of a certain LED device is infiltrated by the liquid metal sticking point on a certain soldering pad, the liquid metal sticking point fully spreads on the soldering surface and the soldering pad, And under the action of its own surface tension, it is flattened in the gap between the LED device and the solder pad (that is, a uniform thickness is formed in each place in the gap), thereby reducing or eliminating the inclination of the LED device relative to the solder pad, and realizing that the LED device is aligned with the solder pad and positioned correctly (that is, overlapped with the solder pad as much as possible), so that each LED device can maintain a correct bonding direction with the soldering surface facing the soldering pad, so that it can form an infiltration bond with the soldering surface efficiently; in the step S5, the driving board is removed from the hot liquid, and the temperature of the driving board is reduced to the second temperature zone, so that the first metal in a molten state can be solidified to form a soldering connection between the assembled LED device and the soldering pad, thereby obtaining the LED array device.

[0014] As a preferred embodiment of the present invention, the first metal is a low melting point metal. Specifically, the first metal can be a pure metal or an alloy thereof having a melting point below 400°C. For example, the first metal can be tin, bismuth, indium or an alloy thereof, such as tin-lead alloy, tin-indium alloy, tin-silver alloy, tin-lead-silver alloy, tin-copper alloy, tin-silver-copper alloy, tin-bismuth alloy or tin-bismuth-silver alloy. The first temperature zone can be within a temperature range slightly higher than the melting point of the first metal (about 50°C range). Specifically, the first metal can be a tin-bismuth alloy having a melting point below 150°C, and the first temperature can be set to 150-200°C. This temperature generally does not damage structures such as drive boards and LED devices. The first metal can be pre-set on the pad by printing, coating, plating, spraying, etc., and pre-melted and infiltrated on the pad to form a coating.

[0015] The second metal is a thin metal layer (e.g., 5nm to 1000nm thick) disposed on the soldering surface of the LED device. It is a metal or alloy having a higher melting point than the first metal and easily wetted with the first metal. For example, it can be gold, silver, copper, zinc, iron, or an alloy with the above metal as the main component. The light-emitting surface is generally a film surface of a semiconductor material such as GaP, GaAs, or GaN. In addition, it can also be a transparent conductive film layer such as plated ITO (indium tin oxide).

[0016] As a preferred embodiment of the present invention, the hydrophobic layer is a fluoropolymer coating. For example, the hydrophobic layer can be a coating of a fluoropolymer such as polyhexafluoropropylene, polytetrafluoroethylene (PTFT / Teflon), polyperfluoroethylene propylene (FEP), polytrifluoroethylene, polyvinylidene fluoride (PVDF), fluorosilicone resin, etc. The hydrophobic layer can be disposed on the light-emitting surface of the LED device by spraying, vacuum evaporation, etc. The hydrophobic layer can be removed by chemical cleaning, plasma cleaning, etc. after the LED device is set to ensure the conductivity of the electrode on the light-emitting surface.

[0017] As a preferred solution of the present invention, the size of the soldering pad is less than or equal to the size of the LED device. More preferably, the size of the soldering pad is 0.5 to 1.0 times the size of the LED device. Thus, when a soldering pad is attached to an LED device, it is completely occupied by the LED device to achieve one-to-one soldering.

[0018] As another preferred solution of the present invention, the size of the soldering pad is larger than the size of the LED device; in step S4, multiple LED devices are attached to one soldering pad to achieve one-to-many soldering. Specifically, the number of LED devices attached to different soldering pads can be the same or different.

[0019] Generally, the shapes and sizes of the LED devices are the same. According to the requirements of the spacing, brightness, cost, etc. of the LED devices, as a preferred embodiment of the present invention, the size of the LED device is 1 to 500 μm. More preferably, the size of the LED device is 20 to 50 μm. This can meet the design requirements of the driver board as a direct display (that is, the LED device is directly used as a display pixel). Generally, the aspect ratio of the outline of the LED device is not greater than 1.2, especially when it is square, round (including rounded square or rounded polygon) or polygon, which is conducive to the adhesion of the LED device to the pad.

[0020] The hot liquid can be a liquid with a high boiling point or vaporization temperature, such as paraffin oil, silicone oil, etc. As a preferred embodiment of the present invention, the hot liquid is composed of molten rosin. Since the vaporization temperature of molten rosin is relatively high, it can remain in a liquid state in the first temperature zone, and can remove the oxide layer on the first metal and the second metal, thereby improving their wettability.

[0021] As a preferred solution of the present invention, the multiple LED devices forming the LED floating layer in step S3 are arranged continuously and densely. Specifically, the LED devices can be driven to gather, and in the LED floating layer, the adjacent LED devices are close to each other, which can reduce the curvature of the liquid surface between the LED devices. Therefore, when the LED devices gather, the adjacent LED devices are more inclined to be close to each other, so that the LED devices forming the LED floating layer can be close to each other and present a continuous and dense arrangement; thus, in step S3, the first board surface of the driving board can be made to form a surface contact with the bottom of the LED floating layer, and each pad within the contact surface has an LED device corresponding to it and forms a contact, thereby further improving the adhesion rate of each pad.

[0022] As a further preferred embodiment of the present invention, the surface of the hot liquid is provided with a gathering area; in the step S3, the LED devices floating on the surface of the hot liquid are gathered in the gathering area to form the LED floating layer that tightly covers the gathering area.

[0023] As a further preferred embodiment of the present invention, the gathering area is surrounded by barrier bars arranged on the surface of the hot liquid. The barrier bars are used to limit the movement of the LED devices on the surface of the hot liquid, thereby causing the LED devices to gather in the gathering area. Specifically, the barrier bars can be arranged in a C-shaped, U-shaped or other shape with one side opening to form the gathering area, and the outer side of the opening is the upstream area of ​​the gathering area, thereby driving the LED devices from the upstream of the gathering area to flow into the gathering area from the opening, so as to gather and spread in the gathering area to form a close arrangement.

[0024] As a further preferred embodiment of the present invention, the size of the gathering area is larger than the size of the driving plate.

[0025] As a further preferred solution of the present invention, in step S3, the LED device is blown into the gathering area by blowing air on the surface of the hot liquid. The blowing temperature can be set above the first temperature zone.

[0026] As another further preferred solution of the present invention, in step S3, the hot liquid is made to flow from the lower side of the gathering area, and the LED devices are driven to gather in the gathering area by the flowing hot liquid. Specifically, the hot liquid is made to flow from the upstream of the gathering area to the lower part of the gathering area, so as to drive the floating LED devices to gather in the gathering area.

[0027] As a further preferred embodiment of the present invention, in step S5, the first board surface of the driving board is facing upward under the gathering area, and the driving board is pulled upward from the gathering area at an inclined angle, so that the LED devices of the LED floating layer are densely attached to the first board surface of the driving board. By controlling the driving board to be at an inclined angle (such as 3° to 30°), the LED floating layer can be retained on the first board surface of the driving board, and the hot liquid between the LED floating layer and the first board surface of the driving board is discharged, so that the LED devices of the LED floating layer are densely attached to the first board surface of the driving board.

[0028] As a further preferred embodiment of the present invention, in step S5, the driving plate is pulled upward from the gathering area at an inclined angle starting from the upstream of the gathering area. Thus, during the pulling process, the LED devices of the LED floating layer are restricted by the gathering area, and are not easy to disperse and can be densely attached on the first plate surface of the driving plate (if the pulling is started from the other side, the flow of the discharged hot liquid may disperse the LEDs, making it impossible to densely attach).

[0029] As a preferred embodiment of the present invention, in step S5, after the driving board is removed from the hot liquid, the driving board is immersed in the hot liquid again to remove the LED devices on the driving board that are not bonded to the pads, and then the driving board is removed from the hot liquid. In the process of immersing the driving board back into the hot liquid, the LED devices that are not bonded to the pads will separate from the driving board and float back to the liquid surface of the hot liquid due to the repulsion of the hot liquid by its hydrophobic layer, thereby separating from the driving board, and the driving board only retains the LED devices bonded to the pads (the bonding force between the first metal and the second metal layer is very large, and the LED hydrophobic layer's repulsion of the hot liquid makes it difficult to separate them).

[0030] As a further preferred solution of the present invention, an immersion zone is provided upstream of the gathering zone; in step S5, the driving board is immersed in the hot liquid again from the immersion zone, thereby allowing the removed LED devices to flow back from the upstream of the gathering zone to the gathering zone, forming a cycle.

[0031] The present invention also provides a self-assembly device for an LED array device, characterized in that it includes a heating pool containing hot liquid, a heating device for heating the hot liquid in the heating pool, a driving board and a driving board bracket capable of driving the driving board to move, the driving board is installed on the driving board bracket and the first plate body of the driving board is arranged facing upward, a plurality of solder pads constituting a solder pad array are arranged on the surface of the first plate body of the driving board, and each solder pad is provided with a first metal; the heating pool is used to accommodate a large number of LED devices, and the large number of LED devices form an LED floating layer on the liquid surface of the hot liquid; the driving board bracket has the following motion states: (1) the hot liquid in the heating pool is heated by the heating device to a temperature in the first temperature zone higher than the melting point of the first metal Under the following conditions, the driver board bracket immerses the driver board into the hot liquid, so that the first metal on each soldering pad on the driver board melts in the hot liquid to form liquid metal sticky points; (2) the first board surface of the driver board is in contact with the bottom of the LED floating layer, and each liquid metal sticky point is in contact with the second metal of the soldering surface of the LED device corresponding to the bottom of the LED floating layer and forms a bond; (3) after the bonding is completed, the driver board bracket lifts the driver board upward from the hot liquid surface, and outside the hot liquid, the driver board is cooled to a second temperature zone lower than the melting point of the first metal, so that the liquid metal sticky points solidify on the second metal so that the soldering surface of the attached LED device is soldered to the soldering pad, thereby manufacturing the LED array device.

[0032] Generally, the heating device mentioned above adopts a heating plate or an electric heater (such as a heating rod).

[0033] When using the above self-assembly device, in order to make the LED device float on the surface of the hot liquid, generally, the hot liquid can be prepared first, and then the LED device can be added to the hot liquid. During the addition of the LED device, the hydrophobic layer of the LED device repels the hot liquid and makes the LED device float on the surface of the hot liquid to form an LED floating layer. For some LED devices that sink into the hot liquid, bubbles or ultrasonic waves can be introduced into the hot liquid to make the hydrophobic layer adhere to the bubbles and float to the liquid surface, thereby making these LED devices float on the surface of the hot liquid in a directional manner with the light-emitting surface facing upward and the welding surface facing downward; when the first board surface of the driving board is in contact with the bottom of the LED floating layer, at the corresponding position of the soldering pad, the LED device maintains the correct bonding direction with the soldering surface facing the soldering pad, so that it can form an efficient infiltration bonding with the soldering surface; the driving board is removed from the hot liquid, and the temperature of the driving board is reduced to the second temperature zone, so that the first metal in a molten state can be solidified to form a soldering of the assembled LED device and the soldering pad, thereby obtaining the LED array device.

[0034] As a preferred solution of the present invention, the drive plate bracket has a J-shaped arm.

[0035] As a preferred solution of the present invention, the front and rear sides of the heating pool are respectively provided with a hot liquid reflux port and a hot liquid outlet, and the hot liquid surface in the heating pool is provided with a gathering area, and the gathering area is close to the hot liquid outlet; the self-assembly device also includes a hot liquid circulation flow device, which is arranged outside the heating pool, and the hot liquid outlet is connected to the hot liquid reflux port through the hot liquid circulation flow device. During operation, the hot liquid in the heating pool can be driven by the hot liquid circulation flow device to flow from the hot liquid reflux port to the hot liquid outlet, so that the hot liquid flows from the upstream of the gathering area to the lower part of the gathering area, and the floating LED devices are driven to gather in the gathering area by the flowing hot liquid, so as to form the LED floating layer that tightly covers the gathering area.

[0036] As a further preferred embodiment of the present invention, the hot liquid circulation flow device comprises a circulation pump, a first infusion tube and a second infusion tube, one end of the first infusion tube is connected to the hot liquid outlet of the heating pool, the other end of the first infusion tube is connected to the liquid inlet of the circulation pump, one end of the second infusion tube is connected to the liquid outlet of the circulation pump, and the other end of the first infusion tube is connected to the hot liquid reflux port. The hot liquid circulation flow device is used to drive the hot liquid to flow from the front side to the rear side, thereby driving the LED devices floating on the surface of the hot liquid to move to the rear side and gather.

[0037] As a further preferred embodiment of the present invention, the gathering area is surrounded by barrier bars arranged on the surface of the hot liquid, and the barrier bars are connected to the top of the heating pool. The barrier bars are used to limit the movement of the LED devices on the surface of the hot liquid, thereby causing the LED devices to gather in the gathering area. Specifically, the barrier bars can be set to a shape with one side opening, such as a C-shape or a U-shape, to form the gathering area, and the outer side of the opening is the upstream area of ​​the gathering area, thereby driving the LED devices from the upstream to flow into the gathering area from the opening to gather in the gathering area and spread out to form a close arrangement.

[0038] As a further preferred embodiment of the present invention, the size of the gathering area is larger than the size of the driving plate.

[0039] Compared with the prior art, the present invention has the following advantages:

[0040] The present invention can not only greatly improve the manufacturing efficiency of the LED array device and meet the requirements of mass production, but also effectively reduce the manufacturing difficulty and cost of the LED array device. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the structure of the self-assembly device provided in Example 1 of the preferred embodiment of the present invention.

[0042] Figure 2 yes Figure 1 Schematic diagram of the structure of the driving board in the self-assembly device shown.

[0043] Figure 3 It is a schematic structural diagram of the LED floating layer formed in step S3 of the manufacturing method provided in Example 1 of the preferred implementation manner of the present invention.

[0044] Figure 4 It is a process schematic diagram of step S4 in the manufacturing method provided in Example 1 of the preferred implementation manner of the present invention.

[0045] Figure 5 It is a process schematic diagram of step S5 in the manufacturing method provided in Example 1 of the preferred implementation manner of the present invention.

[0046] Figure 6 yes Figure 6 A partial enlarged view of .

[0047] Figure 7 It is a schematic diagram of the process of automatically aligning and straightening the LED device with the soldering pad under the surface tension of the first metal in a molten state in step S4 of the manufacturing method provided in Example 1 of the preferred embodiment of the present invention.

[0048] Figure 8 It is a process schematic diagram of step S5 in the manufacturing method provided in Example 2 of the preferred implementation manner of the present invention. DETAILED DESCRIPTION

[0049] Embodiment 1: Figure 1-Figure 7 As shown, the manufacturing method of the LED array device provided in this embodiment includes the following steps:

[0050] S1, providing a driving board 1, wherein a plurality of pads 12 constituting a pad 12 array are disposed on a first board surface 11 of the driving board 1, and a first metal 13 is disposed on each pad 12;

[0051] S2. Provide a large number of LED devices 2, each of which has a light-emitting surface 21 and a welding surface 22 facing away from each other, wherein the light-emitting surface 21 is provided with a hydrophobic layer 23, and the welding surface 22 is provided with a second metal 24, wherein the melting point of the second metal 24 is higher than that of the first metal 13, and the second metal 24 can be wetted by the molten first metal 13;

[0052] S3, applying a large number of LED devices 2 to a hot liquid 30 whose temperature reaches a first temperature zone, wherein the first temperature zone is a temperature interval higher than the melting point of the first metal 13; utilizing the hydrophobic layer 23 of the LED device 2 to repel the hot liquid 30, so that the LED device 2 floats on the liquid surface of the hot liquid 30 with its light emitting surface 21 facing upward and the welding surface 22 facing downward, thereby forming an LED floating layer 20 on the liquid surface of the hot liquid 30, wherein the LED floating layer 20 has a bottom formed by the welding surface 22 of the LED device 2;

[0053] S4, immersing the driving board 1 into the hot liquid 30, so that the first metal 13 on each pad 12 on the driving board 1 melts in the hot liquid 30 to form liquid metal adhesive points 130, and the first board surface 11 of the driving board 1 contacts the bottom of the LED floating layer 20, and each liquid metal adhesive point 130 contacts and bonds with the second metal 24 of the welding surface 22 of the LED device 2 corresponding to the bottom of the LED floating layer 20, and the bonded LED device 2 is automatically aligned with the corresponding pad 12 and positioned correctly;

[0054] S5. Remove the driving board 1 from the hot liquid 30 and cool it down to a second temperature zone, which is a temperature range lower than the melting point of the first metal 13, so that the liquid metal sticky point 130 solidifies on the second metal 24 to form a weld between the welding surface 22 of the adhered LED device 2 and the welding pad 12, thereby obtaining an LED array device.

[0055] The light-emitting surface 21 and the welding surface 22 (P pole, N pole) of the LED device 2 are opposite to each other, and this LED device 2 is generally called a vertical structure LED device. In order to obtain the desired light-emitting color, the semiconductor layer of the LED device 2 can be selected from GaAs, GaP, SiC, GaN and other materials. Generally, the LED devices 2 are all LED devices 2 of the same light-emitting color or semiconductor material. For example, the LED device 2 is a GaN blue light LED, so that a certain color conversion layer (such as quantum dots, phosphor coating) can be added later to obtain color. The semiconductor layer (such as P-type layer, N-type layer, quantum well layer) of the LED device 2 is generally grown on an epitaxial substrate (such as sapphire) by epitaxy (such as epitaxy by MOCVD), and finally peeled off from the epitaxial substrate by laser peeling and other processes. As a result, the LED device 2 generally has a diaphragm structure, and its P pole and N pole are respectively located on two opposite surfaces of the device, one of which can be the above-mentioned light-emitting surface 21, and the other surface forms a welding surface 22 by setting a second metal 24 layer. Generally, the thickness of the LED device 2 is within 20 μm. When the size of the LED device 2 is larger (such as ≥100 μm), the electrode of its non-light-emitting surface 21 can also be bonded to a thicker (such as ≥50 μm) supporting conductor layer, such as a conductive silicon layer or a metal layer, and the outer side surface of the supporting conductor layer is the welding surface 22 of the LED device 2.

[0056] In the above manufacturing method, in step S3, in order to make the LED device 2 float on the liquid surface of the hot liquid 30, generally, the hot liquid 30 can be prepared first, and then a large number of LED devices 2 are added to the hot liquid 30. During the addition of the LED devices 2, the hydrophobic layer 23 of the LED device 2 repels the hot liquid 30, so that the LED device 2 floats on the liquid surface of the hot liquid 30 to form an LED floating layer 20. For some LED devices 2 that sink into the hot liquid 30, bubbles or ultrasonic waves can be introduced into the hot liquid 30 so that the hydrophobic layer 23 adheres to the bubbles and floats to the liquid surface, thereby making these LED devices 2 with the light emitting surface 21 facing upward and the LED devices 2 floating on the liquid surface 20. The LED components 2 are floated on the surface of the hot liquid 30 with the welding surface 22 facing downward; in step S4, when the first board surface 11 of the driving board 1 is in contact with the bottom of the LED floating layer 20, at the corresponding position of the soldering pad 12, the LED components 2 are all in the correct bonding direction with the welding surface 22 facing the soldering pad 12, so that they can form an efficient infiltration bonding with the welding surface 22; in step S5, the driving board 1 is removed from the hot liquid 30, and the temperature of the driving board 1 is reduced to the second temperature zone, so that the first metal 13 in a molten state can be solidified to form a solder joint between the assembled LED components 2 and the soldering pad 12, thereby obtaining an LED array device.

[0057] In the present embodiment, the first metal 13 is a low melting point metal. Specifically, the first metal 13 may be a pure metal or an alloy thereof having a melting point below 400°C. For example, the first metal 13 may be tin, bismuth, indium or an alloy thereof, such as a tin-lead alloy, a tin-indium alloy, a tin-silver alloy, a tin-lead-silver alloy, a tin-copper alloy, a tin-silver-copper alloy, a tin-bismuth alloy or a tin-bismuth-silver alloy. The first temperature zone may be within a temperature range slightly higher than the melting point of the first metal 13 (in the range of about 50°C). Specifically, the first metal 13 may be a tin-bismuth alloy having a melting point below 150°C, and the first temperature may be set to 150-200°C. This temperature generally does not damage the structures such as the driving board 1 and the LED device 2. The first metal 13 may be pre-set on the pad 12 by printing, coating, plating, spraying, etc., and pre-melted and infiltrated on the pad 12 to form a coating.

[0058] In this embodiment, the second metal 24 is a thin metal layer (e.g., a thickness of 5 nm to 1000 nm) disposed on the welding surface 22 of the LED device 2, which is a metal or alloy having a higher melting point than the first metal 13 and easily wetted with the first metal 13, for example, it can be gold, silver, copper, zinc, iron, or an alloy with the above metal as a main component. The light-emitting surface 21 is generally a film surface of a semiconductor material such as GaP, GaAs, or GaN. In addition, it can also be a transparent conductive film layer such as plated ITO (indium tin oxide).

[0059] In this embodiment, the hydrophobic layer 23 is a fluorine-containing polymer coating. For example, the hydrophobic layer 23 can be a coating of a fluorine-containing polymer such as polyhexafluoropropylene, polytetrafluoroethylene (PTFT / Teflon), polyperfluoroethylene propylene (FEP), polytrifluoroethylene, polyvinylidene fluoride (PVDF), fluorosilicone resin, etc. The hydrophobic layer 23 can be disposed on the light-emitting surface 21 of the LED device 2 by spraying, vacuum evaporation, etc., and can also be removed by chemical cleaning, plasma cleaning, etc. after the LED device 2 is set, so as to ensure the conductivity of the electrode of the light-emitting surface 21.

[0060] In this embodiment, the shape and size of the LED device 2 are the same, and the size of the LED device 2 is 20-50 μm. This can meet the design requirements of the driver board 1 as a direct display (that is, the LED device 2 is directly used as a display pixel). Specifically, the aspect ratio of the outline of the LED device 2 is not greater than 1.2, especially it is square, round (including rounded square or rounded polygon) or polygon, which is conducive to the adhesion of the LED device 2 on the pad 12.

[0061] In this embodiment, the hot liquid 30 is made of molten rosin. Since the molten rosin has a high vaporization temperature, it can remain in liquid state in the first temperature zone and can remove the oxide layer on the first metal 13 and the second metal 24, thereby improving their wettability.

[0062] In this embodiment, the plurality of LED devices 2 forming the LED floating layer 20 in step S3 are arranged continuously and densely. Specifically, the LED devices 2 can be driven to gather, and in the LED floating layer 20, the adjacent LED devices 2 are close to each other, which can reduce the curvature of the liquid surface between the LED devices 2. Therefore, when the LED devices 2 gather, the adjacent LED devices 2 are also more inclined to be close to each other, so that the LED devices 2 forming the LED floating layer 20 can be close to each other and present a continuous and dense arrangement; thus, in step S3, the first board surface 11 of the driving board 1 can be in surface contact with the bottom of the LED floating layer 20, and each pad 12 within the contact surface has an LED device 2 corresponding to it and forms contact, thereby further improving the adhesion rate of each pad 12.

[0063] In this embodiment, the liquid surface of the hot liquid 30 is provided with a gathering area 300 ; in step S3 , the LED devices 2 floating on the liquid surface of the hot liquid 30 are gathered in the gathering area 300 to form an LED floating layer 20 that tightly covers the gathering area 300 .

[0064] In this embodiment, the gathering area 300 is surrounded by barrier bars 310 disposed on the surface of the hot liquid 30, and the barrier bars 310 are connected to the top of the heating pool 3. The barrier bars 310 are used to limit the movement of the LED devices 2 on the surface of the hot liquid 30, thereby causing the LED devices 2 to gather in the gathering area 300. Specifically, the barrier bars 310 are arranged in a U-shaped shape with an opening 3101 on one side to form the gathering area 300, and the outer side of the opening is the upstream area of ​​the gathering area 300, thereby driving the LED devices 2 from the upstream from the opening 3101 to flow into the gathering area 300 so as to gather and spread in the gathering area 300 to form a close arrangement.

[0065] In this embodiment, the size of the gathering area 300 is larger than the size of the driving plate 1 .

[0066] In this embodiment, in step S3, the hot liquid 30 is made to flow from the lower side of the gathering area 300, and the flowing hot liquid 30 is used to drive the LED devices 2 to gather in the gathering area 300. Specifically, the hot liquid 30 is made to flow from the upstream of the gathering area 300 to the lower part of the gathering area 300, so as to drive the floating LED devices 2 to gather in the gathering area 300.

[0067] In this embodiment, an immersion zone 320 is provided upstream of the gathering zone 300; in step S3, the driving board 1 starts from the immersion zone 320 upstream of the gathering zone 300, and makes the first board body surface 11 of the driving board 1 face upward under the gathering zone 300, and pulls the driving board 1 upward from the gathering zone 300 at an inclined angle (such as 3°~30°), so that the LED devices 2 of the LED floating layer 20 are densely attached to the first board body surface 11 of the driving board 1. Therefore, during the pulling process, the LED devices 2 of the LED floating layer 20 are restricted by the gathering area 300, and are not easy to disperse but can be densely attached on the first board body surface 11 of the driving board 1 (if the pulling is started from the other side, the flow of the removed hot liquid 30 may disperse the LEDs, making it impossible to densely attach). By controlling the driving board 1 at a tilt angle, the LED floating layer 20 can be retained on the first board body surface 11 of the driving board 1, and the hot liquid 30 between the LED floating layer 20 and the first board body surface 11 of the driving board 1 is removed, so that the LED devices 2 of the LED floating layer 20 are densely attached on the first board body surface 11 of the driving board 1.

[0068] The present embodiment also provides a self-assembly device for an LED array device, comprising a driving board 1, a heating pool 3 containing hot liquid 30, a heating device 4 for heating the hot liquid 30 in the heating pool 3, a driving board bracket 5 capable of driving the driving board 1 to move, and a hot liquid circulation device 6, wherein the driving board 1 is mounted on the driving board bracket 5 and the first board surface 11 of the driving board 1 is arranged upward, a plurality of solder pads 12 constituting a solder pad 12 array are arranged on the first board surface 11 of the driving board 1, and each solder pad 12 is arranged with a first metal 13; a hot liquid reflux port 301 and a hot liquid outlet 302 are respectively arranged on the front and rear sides of the heating pool 3, a gathering area 300 is arranged on the liquid surface of the hot liquid 30 in the heating pool 3, and the gathering area 300 is close to the hot liquid outlet 302; the hot liquid circulation device 6 is arranged outside the heating pool 3, and the hot liquid outlet 302 is connected to the hot liquid reflux port 301 through the hot liquid circulation device 6.

[0069] In this embodiment, the driving plate bracket 5 has a J-shaped arm 51 .

[0070] In this embodiment, the hot liquid circulation device 6 includes a circulation pump 61, a first liquid infusion pipe 62 and a second liquid infusion pipe 63. One end of the first liquid infusion pipe 62 is connected to the hot liquid outlet 302 of the heating pool 3, and the other end of the first liquid infusion pipe 62 is connected to the liquid inlet of the circulation pump 61. One end of the second liquid infusion pipe 63 is connected to the liquid outlet of the circulation pump 61, and the other end of the first liquid infusion pipe 62 is connected to the hot liquid reflux port 301. The hot liquid circulation device 6 is used to drive the hot liquid 30 to flow from the front side to the rear side, thereby driving the LED devices 2 floating on the surface of the hot liquid 30 to move to the rear side and gather.

[0071] In this embodiment, the gathering area 300 is surrounded by barrier bars 310 disposed on the surface of the hot liquid 30. The barrier bars 310 are used to limit the movement of the LED devices 2 on the surface of the hot liquid 30, thereby causing the LED devices 2 to gather in the gathering area 300. Specifically, the barrier bars 310 are configured to be U-shaped with one side open to form the gathering area 300, and the outer side of the opening is the upstream area of ​​the gathering area 300, thereby driving the LED devices 2 from the upstream to flow from the opening into the gathering area 300 to gather in the gathering area 300 and spread out to form a close arrangement.

[0072] Here's a quick rundown of how this self-assembling device works:

[0073] The heating pool 3 is used to accommodate a large number of LED devices 2. The hot liquid circulation flow device 6 can drive the hot liquid 30 in the heating pool 3 to flow from the hot liquid reflux port 301 to the hot liquid outlet 302, so that the hot liquid 30 flows from the upstream of the gathering area 300 to the lower part of the gathering area 300, and the floating LED devices 2 are driven to gather in the gathering area 300 by the flowing hot liquid 30, so as to form an LED floating layer 20 that is tightly covered in the gathering area 300; the driving plate bracket 5 has the following motion states: (1) the hot liquid 30 in the heating pool 3 is heated by the hot liquid 30; Under the condition that the temperature of the first metal 13 is heated to a first temperature zone higher than the melting point of the first metal 13, the driving board bracket 5 immerses the driving board 1 into the hot liquid 30; (2) the first metal 13 on each pad 12 on the driving board 1 is melted in the hot liquid 30 to form a liquid metal adhesive point 130, and the first board surface 11 of the driving board 1 is in contact with the bottom of the LED floating layer 20, and each liquid metal adhesive point 130 is in contact with the second metal 24 of the welding surface 22 of the LED device 2 corresponding to the bottom of the LED floating layer 20 and forms a bond. After the bonding is completed, the driving board bracket 5 lifts the driving board 1 upward from the liquid surface of the hot liquid 30 and cools the driving board 1 to a second temperature zone lower than the melting point of the first metal 13, so that the liquid metal adhesive point 130 solidifies on the second metal 24 so that the welding surface 22 of the attached LED device 2 is welded to the pad 12, thereby manufacturing an LED array device.

[0074] Example 2: Reference Figure 8 , when other parts are the same as those of the first embodiment, the difference is that: in the present embodiment, in step S5, after the driving board 1 is removed from the hot liquid 30, the driving board 1 is immersed in the hot liquid 30 again from the gathering area 300 to remove the LED devices 2 on the driving board 1 that are not bonded to the pads 12, and then the driving board 1 is removed from the gathering area 300. In the process of immersing the driving board 1 back into the hot liquid 30 again, the LED devices 2 that are not bonded to the pads 12 will separate from the driving board 1 and float back to the liquid surface of the hot liquid 30 due to the repulsion of the hot liquid 30 by its hydrophobic layer 23, thereby separating from the driving board 1, and the driving board 1 only retains the LED devices 2 bonded to the pads 12 (the bonding force between the first metal 13 and the second metal 24 layers is very large, and it is difficult for the LED hydrophobic layer 23 to repel the hot liquid 30 to separate them).

[0075] In this embodiment, in step S5, the driving board 1 is immersed again in the hot liquid 30 from the immersion area 320. Thus, the removed LED devices 2 can flow back from the upstream of the gathering area 300 to the inside of the gathering area 300, forming a cycle.

[0076] In addition, it should be noted that the names of the various parts of the specific embodiments described in this specification may be different, and any equivalent or simple changes made based on the structure, features and principles of the patent concept of the present invention are included in the protection scope of the patent of the present invention. Those skilled in the art of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for manufacturing an LED array device, characterized in that The steps include: S1. Provide a driving board, wherein a plurality of pads constituting a pad array are arranged on a first board surface of the driving board, and a first metal is arranged on each pad; S2. Provide a large number of LED devices, each of which has a light-emitting surface and a welding surface facing away from each other, wherein the light-emitting surface is provided with a hydrophobic layer, and the welding surface is provided with a second metal, the melting point of the second metal is higher than that of the first metal, and the second metal can be wetted by the molten first metal; S3, applying a large number of LED devices to a hot liquid whose temperature reaches a first temperature zone, the first temperature zone being a temperature interval higher than the melting point of the first metal; utilizing the hydrophobic layer of the LED device to repel the hot liquid, so that the LED device floats on the liquid surface of the hot liquid with its light-emitting surface facing upward and the welding surface facing downward, the liquid surface of the hot liquid is provided with a gathering area, and an immersion area is provided upstream of the gathering area, so that the hot liquid flows from the lower side of the gathering area, and the LED devices floating on the liquid surface of the hot liquid are driven by the flowing hot liquid to gather in the gathering area, so as to form an LED floating layer that tightly covers the gathering area, and the LED floating layer has a bottom formed by the welding surface of the LED device; S4, immersing the driving board into the hot liquid, so that the first metal on each pad on the driving board melts in the hot liquid to form liquid metal sticky points, and the first board surface of the driving board contacts the bottom of the LED floating layer, and each liquid metal sticky point contacts and forms adhesion with the second metal of the welding surface of the LED device corresponding to the bottom of the LED floating layer, and the bonded LED device is automatically aligned with the corresponding pad and corrected; S5. First, the driving board is moved out from the hot liquid, and the driving board is immersed in the hot liquid again from the immersion zone to remove the LED devices on the driving board that are not bonded to the pads. Then, the driving board is moved out of the gathering zone from the hot liquid, and the temperature is reduced to the second temperature zone. The second temperature zone is a temperature range lower than the melting point of the first metal, so that the liquid metal sticking point solidifies on the second metal to form a weld between the welding surface of the adhered LED device and the pad, thereby obtaining the LED array device.

2. The method for manufacturing an LED array device according to claim 1, wherein: The gathering area is surrounded by barrier strips arranged on the surface of the hot liquid.

3. The method for manufacturing an LED array device according to claim 1, characterized in that: The size of the collecting area is larger than the size of the driving plate.

4. The method for manufacturing an LED array device according to claim 1, wherein: In step S5, the first board surface of the driving board is facing upward under the gathering area, and the driving board is pulled upward from the gathering area at an inclined angle, so that the LED devices of the LED floating layer are densely attached to the first board surface of the driving board.

5. The method for manufacturing an LED array device according to claim 4, characterized in that: In the step S5, the driving plate is pulled upward from the gathering area at an inclined angle starting from the upstream of the gathering area.

6. A self-assembly device for an LED array device, characterized in that: The invention comprises a heating pool containing hot liquid, a heating device for heating the hot liquid in the heating pool, a hot liquid circulation device, a driving plate and a driving plate bracket capable of driving the driving plate to move; a hot liquid reflux port and a hot liquid outlet are respectively arranged on the front and rear sides of the heating pool; a gathering area is arranged on the hot liquid surface in the heating pool, the gathering area is close to the hot liquid outlet, and an immersion area is arranged upstream of the gathering area; the hot liquid circulation device is arranged outside the heating pool, and the hot liquid outlet is connected with the hot liquid reflux port through the hot liquid circulation device; The heating pool is used to accommodate a large number of LED devices. The hot liquid circulation flow device can drive the hot liquid in the heating pool to flow from the hot liquid reflux port to the hot liquid outlet, so that the hot liquid flows from the upstream of the gathering area to the lower part of the gathering area, and the floating LED devices are driven to gather in the gathering area by the flowing hot liquid to form an LED floating layer that tightly covers the gathering area; the driving board is installed on the driving board bracket and the first board body of the driving board is arranged facing upward. A plurality of pads constituting a pad array are arranged on the surface of the first board body of the driving board, and each pad is provided with a first metal; The driving board bracket has the following motion states: (1) under the condition that the hot liquid in the heating pool is heated by the heating device to a first temperature zone with a temperature higher than the melting point of the first metal, the driving board bracket immerses the driving board into the hot liquid, so that the first metal on each soldering pad on the driving board melts in the hot liquid to form liquid metal sticky points; (2) the first board surface of the driving board is in contact with the bottom of the LED floating layer, and each liquid metal sticky point is in contact with the second metal of the soldering surface of the LED device corresponding to the bottom of the LED floating layer and forms a bond; (3) after the bonding is completed, the driving board bracket lifts the driving board upward from the hot liquid surface, and immerses the driving board from the immersion zone into the hot liquid again to remove the LED device on the driving board that is not bonded to the soldering pad, and then moves the driving board out of the hot liquid from the gathering zone. Outside the hot liquid, the driving board is cooled to a second temperature zone with a temperature lower than the melting point of the first metal, so that the liquid metal sticky points solidify on the second metal so that the soldering surface of the attached LED device is soldered to the soldering pad, thereby manufacturing the LED array device.

7. The self-assembly device of the LED array device according to claim 6, characterized in that: The drive plate bracket has a J-shaped arm.

8. The self-assembly device of the LED array device according to claim 6, characterized in that: The gathering area is surrounded by barrier bars arranged on the surface of the hot liquid, and the barrier bars are connected to the top of the heating pool.

9. The self-assembly device of the LED array device according to claim 6, characterized in that: The hot liquid circulation flow device includes a circulation pump, a first infusion tube and a second infusion tube, one end of the first infusion tube is connected to the hot liquid outlet of the heating pool, the other end of the first infusion tube is connected to the liquid inlet of the circulation pump, one end of the second infusion tube is connected to the liquid outlet of the circulation pump, and the other end of the first infusion tube is connected to the hot liquid reflux port.

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