A method for mass transfer with magnetic alignment and fluid flow

Abstract

The present invention discloses a method for mass transfer with magnetic alignment and fluid alignment, which specifically includes: preparing a micro light-emitting diode as a Micro LED chip, making an N-type electrode with magnetic material, and not processing the P-type electrode; preparing a driving circuit board with magnetic adsorption, making a fixed block of the N-type electrode with magnetic material, and not processing the fixed position of the P-type electrode; positioning the driving circuit board, placing the driving circuit board, a micro magnetic needle and a micro light-emitting diode together in a fluid device; controlling the chip falling posture, applying a magnetic field through a solenoid outside the fluid device, so that the electrode side falls toward the driving circuit board; using a magnetic field to adsorb the N-type electrode on the fixed block: adjusting the position of the P-type electrode through flow field impact. The present invention adopts a method for mass transfer with magnetic alignment and fluid alignment using the above steps, and realizes precise positioning of the chip and the driving circuit board through the joint action of the flow field and the magnetic field, thereby improving the transfer efficiency and yield rate.

Description

Technical Field

[0001] The invention relates to the field of semiconductor optoelectronic technology, and in particular to a method for transferring a large amount of fluid by aligning magnetic force and aligning fluid. Background Art

[0002] Micro LEDs are LED chips that are micrometer-sized. They are semiconductor diodes that can convert electrical energy into light energy. They have the advantages of high luminous efficiency, low power consumption, high contrast, fast response speed and long life. They are widely used in the display and lighting fields. After the production of Micro LED chips is completed, millions or even tens of millions of Micro LED chips need to be transferred to the driver circuit board. The number of transferred chips is huge and the accuracy requirement is extremely high. The mass transfer link is the key link that limits the production capacity in the Mini / Micro LED packaging process, which directly affects the production speed of Mini / Micro LED displays.

[0003] At present, mass transfer has the disadvantages of high technical difficulty and high transfer cost. The process routes include precise pick-up-and-release technology, laser peeling technology, roller transfer technology and self-assembly transfer technology. Currently, the most commonly used is precise pick-up-and-release technology, which can be divided into micro-transfer technology, swing-arm transfer technology, needle-puncture transfer technology and electrostatic force transfer technology. However, due to its own structure, the production capacity is limited and cannot be greatly improved. Roller transfer technology is to place the seal on the surface of the roller and use the adhesion between the seal and the chip to complete the pick-up and release, but the pressure uniformity during the transfer process is difficult to guarantee. Self-assembly technology uses fluid force or magnetic force to drive the chip to complete the transfer. Compared with the other three technologies, it can transfer chips with smaller sizes and more complex structures. It has the advantages of low cost and high efficiency. It is currently the most promising transfer method.

[0004] In the existing technology, the Micro LED array device, mass transfer device and related methods described in patent application 201811268052.1 form a magnetic nano film layer on the epitaxial substrate of the Micro LED array device, so that the film layer acts as an electrode, and the transfer receiving device is provided with a groove with multiple magnetic adsorption holes inside, and the array device is adsorbed in the adsorption holes by the adsorption force of the electrostatic adsorption holes. Since a magnetic nano film layer is formed on one side of the electrode of the micro light-emitting diode, under the action of electrostatic adsorption, after the chip falls into the groove of the receiving device, the light-emitting side of the chip fits with the adsorption hole, and welding cannot be completed, which affects the efficiency and yield of the transfer.

[0005] Patent application 201911046591.5 describes a light-emitting diode display, which performs patterning on the magnetic electrode layer of the micro-light-emitting diode and also performs patterning on the circuit substrate driving the light-emitting diode, and transfers the patterned ... 2 The shape of the patterns on the electrodes is very small, making it difficult to achieve precise transfer through magnetic adsorption. In addition, the chip will deflect under the attraction of the circuit substrate, affecting the transfer efficiency and yield.

[0006] Patent application 201710561814.6 describes a method for mass transfer of micro-light-emitting secondary optical chips, which manufactures Micro LED chips with P-type electrodes and N-type electrodes, and also sets P-type electrode and N-type electrode fixing blocks on the driver circuit board, all of which are placed in a solution, and fixedly mounted on the driver circuit board under the action of magnetic force to achieve mass transfer. During the transfer process, the N-type electrode of the chip will be adsorbed to the P-type fixing block of the driver circuit board, and the P-type electrode will not be adsorbed to the N-type fixing block of the driver circuit board. In addition, the N-type electrode of the chip will be adsorbed to the P-type electrode of other chips, and cannot accurately fall on the specified position of the driver circuit board, resulting in transfer failure, affecting the transfer efficiency and yield. Summary of the invention

[0007] The purpose of the present invention is to provide a mass transfer method with magnetic alignment and fluid alignment, which can achieve precise positioning of the chip and the driver circuit board through the combined action of the flow field and the magnetic field, thereby improving the transfer efficiency and yield rate.

[0008] To achieve the above purpose, the present invention provides a method for transferring a large amount of fluid by aligning the magnetic force and aligning the fluid, and the specific steps are as follows:

[0009] S1. Prepare a micro light-emitting diode as a Micro LED chip: The micro light-emitting diode includes a P-type layer, a light-emitting layer, an N-type layer, a P-type electrode, and an N-type electrode. The light-emitting layer is stacked on one end of the P-type layer, and the N-type layer is stacked on the surface of the light-emitting layer. The surface of the N-type layer is coated with a magnetic material to form an N-type electrode. The N-type electrode has magnetism in a magnetic field, and the P-type electrode is arranged at the other end of the P-type layer.

[0010] S2. Prepare a driving circuit board with magnetic adsorption: a plurality of through holes are provided on the surface of the driving circuit board, and magnetic materials are filled in the through holes to make a fixing block of the N-type electrode. The position of the fixing block corresponds to the N-electrode, and the fixing position of the P-type electrode is not processed. The specific steps include:

[0011] S2.1, using photolithography technology to form a photoresist mask with a pattern on the driver circuit board to expose the through hole;

[0012] S2.2, laying a magnetic material on the photoresist mask and the driving circuit board not covered by the photoresist mask, and injecting the magnetic material into the through hole;

[0013] S2.3, removing the photoresist mask, and the magnetic material remaining on the driving circuit board forms a fixed block of the N-type electrode;

[0014] S3, positioning the driving circuit board: placing the driving circuit board, the needle plate with the micro magnetic needle, and the micro light emitting diode into the fluid device together, the needle plate is located below the driving circuit board, the position of the micro magnetic needle corresponds to the position of the fixed block on the driving circuit board, the fluid device is filled with the flow field solution, one end of the fluid device is provided with a plurality of water inlet pipes, the water inlet pipes are provided with a control valve, the other end of the fluid device is provided with a plurality of water outlet pipes, and the outside of the fluid device is wound with a solenoid coil;

[0015] S4, chip falling posture control: when the micro-LED falls in the flow field solution, the controller switch of the solenoid coil is turned on. After the solenoid coil is energized, it becomes magnetic, so that the falling micro-LED keeps the P-type layer away from the driving circuit board, the N-type electrode and the P-type electrode close to the driving circuit board under the influence of its own gravity and magnetic force, and keeps the N-type electrode lower than the P-type electrode;

[0016] S5, N-type electrode position adsorption: Under the action of gravity and the adsorption of the magnetic force of the micro magnetic needle, the N-type electrode of the micro light-emitting diode falls on the fixed block on the driving circuit board. At this time, the power supply of the solenoid coil is turned off, and the solenoid coil loses its magnetism;

[0017] S6. Adjust the position of the P-type electrode under flow field impact: open the control valve on the water pipe to adjust the flow rate and flow speed of the solution entering the fluid device. The installation direction of the micro light emitting diode is consistent with the flow direction of the flow field solution. The N-type electrode of the micro light emitting diode is fixed by the magnetic field of the micro magnetic needle. The P-type electrode rotates to be aligned under the impact of the flow field solution to complete the massive transfer.

[0018] Preferably, the specific process of preparing a micro light emitting diode as a Micro LED chip in S1 includes:

[0019] S1.1, sequentially growing a P-type layer, a light-emitting layer, and an N-type layer on a substrate;

[0020] S1.2, forming a photoresist mask having a pattern on the surface of the N-type layer by using a photolithography technique;

[0021] S1.3, etching the N-type layer and the light-emitting layer under the protection of the photoresist mask until the P-type layer is exposed;

[0022] S1.4. Remove the photoresist mask, lay magnetic material on the surface of the N-type layer to form an N-type electrode, and grow a P-type electrode at the other end of the P-type layer surface.

[0023] Preferably, the substrate of the micro light emitting diode is sapphire or silicon carbide, the N-type layer and the P-type layer are made of GaN, and the light emitting layer is formed by stacking a plurality of GaN layers.

[0024] Preferably, the magnetic material is one of Al-Ni-Co permanent magnet alloy, Fe-Cr-Co permanent magnet alloy, permanent magnet ferrite, rare earth permanent magnet material or composite permanent magnet material.

[0025] Preferably, a transparent conductive layer is disposed on the surface of the micro light emitting diode, the transparent conductive layer and the light emitting layer are respectively located on both sides of the P-type layer, and the thickness of the transparent conductive layer is 500 nanometers.

[0026] Preferably, the flow field solution is one of acetone, ethanol, isopropanol, alcohol or pure water.

[0027] Preferably, the diameter of the micro magnetic needle is less than 20 microns, and the micro magnetic needle is made of permanent magnetic material with constant magnetic properties.

[0028] Preferably, the height of the fluid device is 50-100 cm, the material of the water inlet pipe and the water outlet pipe of the fluid device is one of PVC, PE, PS or ABS, the maximum diameter of the water inlet pipe is 500 microns, and several water inlet pipes are closely arranged.

[0029] Therefore, the present invention adopts a mass transfer method with magnetic alignment and fluid alignment of the above-mentioned structure, which realizes flexible contact mass transfer of chips with high efficiency and high yield. Compared with patent 201811268052.1, it avoids the problem of micro-light emitting diodes falling back into the driving circuit board; compared with patent 201911046591.5, it avoids the problem of chip deflection during the falling process; compared with patent 201710561814.6, it avoids the problem of large-scale aggregation of chips during the falling process.

[0030] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of an embodiment of a method for transferring a large amount of fluid by magnetic alignment and fluid alignment according to the present invention;

[0032] Figure 2 A schematic diagram of the structure of a micro light emitting diode according to an embodiment of the present invention;

[0033] Figure 3 It is a schematic diagram of the structure of a fluid device and a solenoid coil according to an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the internal structure of a fluid device in which a driving circuit board according to an embodiment of the present invention is placed;

[0035] Figure 5 Schematic diagram of the adsorption process of an N-type electrode under the action of a magnetic field according to an embodiment of the present invention;

[0036] Figure 6 Schematic diagram of the adjustment process of the P-type electrode under the action of the flow field according to an embodiment of the present invention.

[0037] Reference numerals

[0038] 10. Micro light emitting diode; 11. Light emitting layer; 12. N-type layer; 13. N-type electrode; 14. P-type layer; 15. P-type electrode; 20. Driving circuit board; 21. Fixing block; 22. Micro magnetic needle; 30. Fluid device; 31. Solenoid coil; 32. Water inlet pipe; 33. Control valve; 34. Water outlet pipe. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0040] Example

[0041] like Figure 1 As shown, the present invention provides a method for transferring a large amount of fluid by aligning the magnetic force and aligning the fluid, and the specific steps are as follows:

[0042] S1. Prepare a micro light emitting diode 10 as a Micro LED chip: The micro light emitting diode 10 includes a P-type layer 14, a light emitting layer 11, an N-type layer 12, a P-type electrode 15, and an N-type electrode 13. The light emitting layer 11 is stacked on one end of the P-type layer 14, and the N-type layer 12 is stacked on the surface of the light emitting layer 11. The surface of the N-type layer 12 is coated with a magnetic material to form an N-type electrode 13. The N-type electrode 13 has magnetism in a magnetic field, and the P-type electrode 15 is arranged at the other end of the P-type layer 14.

[0043] The specific process is as follows:

[0044] S1.1. A P-type layer 14, a light-emitting layer 11, and an N-type layer 12 are sequentially grown on a substrate; the substrate is sapphire or silicon carbide, the thickness of the substrate is 400 microns, the N-type layer 12 and the P-type layer 14 are made of GaN, and the light-emitting layer 11 is formed by stacking multiple GaN layers, with a maximum of no more than 16 layers; the sum of the thicknesses of the N-type layer 12, the light-emitting layer 11, and the P-type layer 14 is no more than 5 microns.

[0045] S1.2, forming a photoresist mask having a pattern on the surface of the N-type layer 12 by using a photolithography technique;

[0046] S1.3, etching the N-type layer 12 and the light-emitting layer 11 under the protection of the photoresist mask until the P-type layer 14 is exposed;

[0047] S1.4, remove the photoresist mask, lay magnetic material on the surface of the N-type layer 12 by physical vapor deposition technology to form an N-type electrode 13, and grow a P-type electrode 15 at the other end of the surface of the P-type layer 14.

[0048] There are many tiny areas in the magnetic material, and each tiny area has a magnetic field. Under normal circumstances, the magnetic fields cancel each other out, and the whole does not show magnetism to the outside. When the magnetic material is placed in the magnetic field, it is affected by the magnetic field and the entire magnetic field material will show magnetism to the outside and become a magnet.

[0049] A transparent conductive layer can also be provided on the surface of the micro light-emitting diode 10. The transparent conductive layer and the light-emitting layer 11 are respectively located on both sides of the P-type layer 14. During the manufacturing process, the transparent conductive layer is first generated, and then the P-type layer 14, the light-emitting layer 11, and the N-type layer 12 are grown in sequence. The thickness of the transparent conductive layer is 500 nanometers.

[0050] S2, preparing a driving circuit board 20 with magnetic adsorption: a plurality of through holes are provided on the surface of the driving circuit board 20, and a magnetic material is filled in the through holes to make a fixing block 21 of the N-type electrode 13, and the position of the fixing block 21 corresponds to the N-electrode, and the fixing position of the P-type electrode 15 is not processed. The specific steps include:

[0051] S2.1, using photolithography technology to form a photoresist mask with a pattern on the driving circuit board 20 to expose the through hole;

[0052] S2.2, laying a magnetic material on the photoresist mask and the driving circuit board 20 not covered by the photoresist mask, and injecting the magnetic material into the through hole;

[0053] S2.3. Remove the photoresist mask, and the magnetic material remaining on the driving circuit board 20 forms the fixed block 21 of the N-type electrode 13; the magnetic material selected for the N-type electrode 13 and the fixed block 21 is one of aluminum-nickel-cobalt permanent magnet alloy, iron-chromium-cobalt permanent magnet alloy, permanent magnet ferrite, rare earth permanent magnet material or composite permanent magnet material.

[0054] S3. Positioning the driving circuit board 20: placing the driving circuit board 20, the needle plate with the micro magnetic needle 22, and the micro light emitting diode 10 together into the fluid device 30. The height of the fluid device 30 is 50-100 cm. The fluid device 30 is filled with a flow field solution, which is one of acetone, ethanol, isopropanol, alcohol or pure water.

[0055] A plurality of water inlet pipes 32 are provided at one end of the fluid device 30, and a control valve 33 is provided on the water inlet pipes 32. A plurality of water outlet pipes 34 are provided at the other end of the fluid device 30, and a solenoid coil 31 is wound around the outside of the fluid device 30. The material of the water inlet pipes 32 and the water outlet pipes 34 of the fluid device 30 is one of PVC, PE, PS or ABS, and the maximum diameter of the water inlet pipe 32 is 500 microns. The plurality of water inlet pipes 32 are closely arranged.

[0056] The needle plate is located below the driving circuit board 20, and the position of the micro magnetic needle 22 corresponds to the position of the fixed block 21 on the driving circuit board 20. The diameter of the micro magnetic needle 22 is less than 20 microns, and a permanent magnetic material with constant magnetic properties is used to ensure that the micro light-emitting diode 10 can be always fixed on the driving circuit board 20.

[0057] S4. Chip falling posture control: When the micro-LED 10 falls in the flow field solution, the controller switch of the solenoid coil 31 is turned on, and the electrostatic control circuit is stopped from being energized. After being energized, the solenoid coil 31 becomes magnetic, so that the descending micro-LED 10, under the influence of its own gravity and magnetic force, keeps the P-type layer 14 away from the driving circuit board 20, the N-type electrode 13 and the P-type electrode 15 close to the driving circuit board 20, and keeps the N-type electrode 13 lower than the P-type electrode 15.

[0058] S5. Adsorption of the N-type electrode 13: Under the action of gravity and the magnetic force of the micro magnetic needle 22, the N-type electrode 13 of the micro light-emitting diode 10 falls on the fixed block 21 on the driving circuit board 20. At this time, the power supply of the solenoid coil 31 is turned off, and the solenoid coil 31 loses its magnetism.

[0059] S6. Adjust the position of the P-type electrode 15 by flow field impact: open the control valve 33 on the water pipe to adjust the flow rate and flow speed of the solution entering the fluid device 30. The installation direction of the micro light emitting diode 10 is consistent with the flow direction of the flow field solution. The N-type electrode 13 of the micro light emitting diode 10 is fixed by the magnetic field of the micro magnetic needle 22. The P-type electrode 15 rotates to be aligned under the impact of the flow field solution to complete the massive transfer.

[0060] In the embodiment of the present invention, a micro-LED 10 with an N-type electrode 13 as a magnet is manufactured, a micro-magnetic needle 22 is placed under the driving circuit board 20, and a fixing block 21 of the N-type electrode 13 is set on the driving circuit board 20. Finally, the driving circuit board 20, the micro-magnetic needle 22 and the micro-LED 10 are placed in the same fluid device 30. By winding the solenoid on the fluid device 30, the micro-LED 10 is fixed to the fixing block 21 under the adsorption of magnetic force, and then the P-type electrode 15 is straightened by fluid impact in the flow field. Mass transfer can be achieved, which is simple, convenient and rapid, greatly improving production efficiency and reducing production costs.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for transferring a large amount of fluid by magnetic alignment, characterized in that: The specific steps are as follows: S1. Prepare a micro light-emitting diode as a Micro LED chip: The micro light-emitting diode includes a P-type layer, a light-emitting layer, an N-type layer, a P-type electrode, and an N-type electrode. The light-emitting layer is stacked on one end of the P-type layer, and the N-type layer is stacked on the surface of the light-emitting layer. The surface of the N-type layer is coated with a magnetic material to form an N-type electrode. The N-type electrode has magnetism in a magnetic field, and the P-type electrode is arranged at the other end of the P-type layer. S2. Prepare a driving circuit board with magnetic adsorption: a plurality of through holes are provided on the surface of the driving circuit board, and magnetic materials are filled in the through holes to make a fixing block of the N-type electrode. The position of the fixing block corresponds to the N-electrode, and the fixing position of the P-type electrode is not processed. The specific steps include: S2.1, using photolithography technology to form a photoresist mask with a pattern on the driver circuit board to expose the through hole; S2.2, laying a magnetic material on the photoresist mask and the driving circuit board not covered by the photoresist mask, and injecting the magnetic material into the through hole; S2.3, removing the photoresist mask, and the magnetic material remaining on the driving circuit board forms a fixed block of the N-type electrode; S3, positioning the driving circuit board: placing the driving circuit board, the needle plate with the micro magnetic needle, and the micro light emitting diode into the fluid device together, the needle plate is located below the driving circuit board, the position of the micro magnetic needle corresponds to the position of the fixed block on the driving circuit board, the fluid device is filled with the flow field solution, one end of the fluid device is provided with a plurality of water inlet pipes, the water inlet pipes are provided with a control valve, the other end of the fluid device is provided with a plurality of water outlet pipes, and the outside of the fluid device is wound with a solenoid coil; S4, chip falling posture control: when the micro-LED falls in the flow field solution, the controller switch of the solenoid coil is turned on. After the solenoid coil is energized, it becomes magnetic, so that the falling micro-LED keeps the P-type layer away from the driving circuit board, the N-type electrode and the P-type electrode close to the driving circuit board under the influence of its own gravity and magnetic force, and keeps the N-type electrode lower than the P-type electrode; S5, N-type electrode position adsorption: Under the action of gravity and the adsorption of the magnetic force of the micro magnetic needle, the N-type electrode of the micro light-emitting diode falls on the fixed block on the driving circuit board. At this time, the power supply of the solenoid coil is turned off, and the solenoid coil loses its magnetism; S6. Adjust the position of the P-type electrode under flow field impact: open the control valve on the water pipe to adjust the flow rate and flow speed of the solution entering the fluid device. The installation direction of the micro light emitting diode is consistent with the flow direction of the flow field solution. The N-type electrode of the micro light emitting diode is fixed by the magnetic field of the micro magnetic needle. The P-type electrode rotates to be aligned under the impact of the flow field solution to complete the massive transfer.

2. A method for transferring a large amount of fluid by magnetic alignment and fluid alignment according to claim 1, characterized in that: The specific process of preparing micro light-emitting diodes as Micro LED chips in S1 includes: S1.1, sequentially growing a P-type layer, a light-emitting layer, and an N-type layer on a substrate; S1.2, forming a photoresist mask having a pattern on the surface of the N-type layer by using a photolithography technique; S1.3, etching the N-type layer and the light-emitting layer under the protection of the photoresist mask until the P-type layer is exposed; S1.

4. Remove the photoresist mask, lay magnetic material on the surface of the N-type layer to form an N-type electrode, and grow a P-type electrode at the other end of the P-type layer surface.

3. A method for transferring a large amount of fluid by magnetic alignment and fluid alignment according to claim 2, characterized in that: The substrate of the micro light-emitting diode is sapphire or silicon carbide, the N-type layer and the P-type layer are made of GaN, and the light-emitting layer is formed by stacking multiple GaN layers.

4. The method for transferring a large amount of fluid by magnetic alignment and fluid alignment according to claim 1, characterized in that: The magnetic material is one of Al-Ni-Co permanent magnet alloy, Fe-Cr-Co permanent magnet alloy, permanent magnet ferrite, rare earth permanent magnet material or composite permanent magnet material.

5. The method for transferring a large amount of fluid by magnetic alignment and fluid alignment according to claim 3, characterized in that: A transparent conductive layer is arranged on the surface of the micro light emitting diode. The transparent conductive layer and the light emitting layer are respectively located on both sides of the P-type layer. The thickness of the transparent conductive layer is 500 nanometers.

6. A method for transferring a large amount of fluid by magnetic alignment and fluid alignment according to claim 1, characterized in that: The flow field solution is one of acetone, ethanol, isopropanol, alcohol or purified water.

7. A method for transferring a large amount of fluid by magnetic alignment and fluid alignment according to claim 1, characterized in that: The diameter of the micro magnetic needle is less than 20 microns, and the micro magnetic needle is made of permanent magnetic material with constant magnetic property.

8. The method for transferring a large amount of fluid by magnetic alignment and fluid alignment according to claim 1, characterized in that: The height of the fluid device is 50-100 cm. The materials of the water inlet pipe and the water outlet pipe of the fluid device are one of PVC, PE, PS or ABS. The maximum diameter of the water inlet pipe is 500 microns, and several water inlet pipes are closely arranged.

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