Large-area dense array magnetic needle and manufacturing method thereof

Abstract

The invention discloses a large-area dense array magnetic needle and a manufacturing method thereof, and belongs to the technical field of chip mass transfer, the large-area dense array magnetic needle comprises a permanent magnet layer, a magnetizer layer, a magnetic needle seat layer and a magnetic needle tip layer which are connected in sequence through positioning pins, the permanent magnet layer is arranged at the lowermost part, a plurality of magnetic needle seats are arranged on the magnetic needle seat layer in an array mode, and the magnetizer layer is arranged on the magnetic needle seat layer. A plurality of magnetic needle tips are arranged on the magnetic needle tip layer in an array mode, and the manufacturing method of the magnetic needle tip layer is provided. According to the large-area dense array magnetic needle and the manufacturing method thereof, low-cost machining of a large number of dense array magnetic needles is achieved in a powder filling mode, the manufacturing cost in the mass transfer process can be greatly reduced, and the large-area dense array magnetic needle and the manufacturing method thereof have the promoting effect on mass transfer and Micro LED popularization.

Description

Technical Field

[0001] The present invention relates to the technical field of chip mass transfer, and in particular to a large-area dense array of magnetic needles and a manufacturing method thereof. Background Art

[0002] As a new generation of display technology, Micro LED technology has higher brightness and contrast than traditional LCD and OLED technologies, and its response time can reach sub-millisecond level. It also has longer service life and lower power consumption. Therefore, it has broad application prospects in high-resolution display, wearable devices, medical and biological applications, etc., and is considered to be one of the important development directions of future display technology. At present, mass transfer is one of the core problems of Micro LED manufacturing. Since Micro LED needs to accurately transfer millions or even tens of millions of micro LED chips to the display substrate, the transfer accuracy must reach the nanometer level, and the requirements for mass transfer technology are also higher.

[0003] In order to solve the above problems, the industry and academia have proposed a variety of technologies to solve this problem. One of the most cutting-edge technologies is self-assembly technology, which can greatly improve the speed and yield of transfer, including fluid self-assembly technology, magnetic-assisted self-assembly technology, molecular self-assembly technology, shape matching self-assembly technology, etc. Among them, the fluid magnetic self-assembly technology uses the drive of fluid and the magnetic force to automatically assemble Micro LED devices in the fluid to the designated area of ​​the design, which can achieve large-scale chip positioning, alignment and welding. The main implementation method of this technology is to place the chip in the fluid, move the chip to the top of the magnet array through the flow of the fluid, and achieve precise positioning and transfer of the Micro LED chip by precisely controlling the magnet array, combining the advantages of fluid self-assembly technology and magnetic-assisted self-assembly technology. The current magnetic array processing method generally adopts engraving means, which requires engraving operations on each unit on the array, which is repeated many times, takes a long time, is difficult to manufacture on a large scale, and has high requirements on the precision of the processing equipment. The spacing between the processed magnetic needles is large, which increases the cost of mass transfer and affects the yield and efficiency of mass transfer.

[0004] In the prior art, in the invention patent with publication number CN117334797A and patent name "A Flow Magnetic Self-Assembly Mass Transfer Device and Transfer Method", the accurate self-assembly process is achieved by adjusting the flow field and magnetic field, and the shape matching principle of the groove is used to enable the light-emitting diode to complete the posture correction during the adsorption process. However, this solution has too much processing content, and the electromagnetic motion unit and the permanent magnet need to be processed separately, which is not conducive to reducing costs. In the invention patent with publication number CN119050038A and patent name "A Mini LED Chip Grabbing Device and Its Manufacturing Method", a manufacturing method for mass processing magnetic needles through a roller mechanism is proposed, which realizes partial decoupling of the permanent magnetic circuit and the electromagnetic magnetic circuit, and reduces the loss during the operation of the device; the grinding wheel mechanism is used for cutting and processing to realize the whole row and column processing, which can effectively improve the processing efficiency and reduce the cost to a certain extent, but the solution is limited by the size of the grinding wheel itself, and it is difficult to reduce the spacing between the magnetic needles. At the same time, it fails to solve the problem of easy damage to the needle tip. It is also difficult to repair the needle tip after it is damaged, which is easy to affect the yield of the mass transfer process.

[0005] Based on the above problems, a large-area dense array of magnetic needles and a manufacturing method thereof are proposed. Summary of the invention

[0006] The object of the present invention is to provide a large-area dense array of magnetic needles and a manufacturing method thereof to solve the problems in the background technology.

[0007] To achieve the above-mentioned purpose, the present invention provides a large-area dense array of magnetic needles, including a permanent magnet layer, a magnetic conductive layer, a magnetic needle seat layer, and a magnetic needle tip layer connected in sequence by positioning pins, the four of which are tightly fitted, the permanent magnet layer is arranged at the bottom, a plurality of magnetic needle seats are arranged in an array on the magnetic needle seat layer, and a plurality of magnetic needle tips are arranged in an array on the magnetic needle tip layer.

[0008] Preferably, the material of the permanent magnet layer is one or more of aluminum-nickel permanent magnet alloy, iron-chromium-cobalt permanent magnet alloy, permanent magnet ferrite, rare earth permanent magnet and composite permanent magnet material, and the length of the permanent magnet layer is 200~300mm, the width is 200~300mm, and the height is 10~20mm.

[0009] Preferably, the material of the magnetic conductive layer is one or more of industrial pure iron, cobalt-iron alloy, nickel-iron alloy, ferrite and ferrite, and the length of the magnetic conductive layer is 200-300 mm, the width is 200-300 mm, and the height is 1-5 mm.

[0010] Preferably, the materials of the magnetic needle seat layer and the magnetic needle tip layer are one or more of pure aluminum and plastic with zero magnetic permeability, and the length of the magnetic needle seat layer is 200-300 mm, the width is 200-300 mm, and the height is 0.5-1 mm; The magnetic needle tip layer has a length of 200-300 mm, a width of 200-300 mm, and a height of 0.1-0.2 mm.

[0011] Preferably, the materials of the magnetic needle base and the magnetic needle tip are one or more of industrial pure iron, cobalt-iron alloy, nickel-iron alloy, ferrite, and ferrite.

[0012] Preferably, the magnetic needle seat is concentrically arranged with the magnetic needle tip, the diameter of the magnetic needle seat is 0.3-0.5 mm, and the spacing between two adjacent magnetic needle seats is 1-2 mm; The diameter of the magnetic needle tip is 0.1-0.2 mm, and the spacing between two adjacent magnetic needle tips is 1-2 mm.

[0013] Preferably, a plurality of positioning pin holes are provided on the permanent magnet layer, the magnetic conductive layer, the magnetic needle seat layer and the magnetic needle tip layer.

[0014] The present invention also provides a method for manufacturing the large-area dense array magnetic powder magnetic needles, comprising the following steps: S1. Prepare the permanent magnet layer, the magnetic conductive layer, the magnetic needle seat layer, and the magnetic needle tip layer according to the design requirements, and process the positioning pin hole; S2, processing a plurality of needle seat holes distributed in an array on the magnetic needle seat layer, and processing a plurality of needle tip holes distributed in an array on the magnetic needle tip layer, wherein the positions of the needle tip holes correspond to the needle seat holes; S3, move the magnetic needle seat layer to the top of the glass plate, apply a small amount of epoxy glue on the surface of the needle seat hole to seal the top, turn it over after solidification, add lubricant into the needle seat hole, mix magnetic powder and additives into a slurry, fill it into the needle seat hole from top to bottom, mold it in an axial directional magnetic field, and then inject epoxy glue from the top to the inside to fill the gap and seal the top, and completely fix it to form a magnetic needle seat; S4, processing a magnetic needle tip on the magnetic needle tip layer according to the operation of S3; S5. Mechanically position the permanent magnet layer, magnetic conductive layer, magnetic needle seat layer, and magnetic needle tip layer through the positioning pin holes. After installation, use a precision Gauss meter to measure the magnetic density above the magnetic needle array to ensure that the magnetic field density meets the requirements and obtain a large-area dense array of magnetic powder needles.

[0015] Preferably, in the large-area dense array magnetic powder magnetic needles, the permanent magnetic field generated by the permanent magnetic layer passes through the magnetic conductive layer, the magnetic needle seat, and the magnetic needle tip, and generates a permanent magnetic field with peak-valley distribution in both the horizontal and vertical directions on the upper surface of the magnetic needle tip layer, with a peak value ≥50mT and a valley value ≤10mT.

[0016] Therefore, the large-area dense array magnetic needles and the manufacturing method thereof of the present invention have the following beneficial effects: (1) In the present invention, corresponding magnetic base positioning holes and magnetic needle positioning holes are firstly arranged in the magnetic needle base layer and the magnetic needle tip layer, and then magnetic powder is filled into the specified position to form the base hole and the tip hole, thereby forming a specific magnetic needle array. The permanent magnet is guided by the magnetic conductor and the magnetic needle to form a specific peak-valley effect magnetic field at the predetermined position, which can be used to accurately grasp the Micro LED chip and ensure the efficient and orderly progress of the mass transfer process.

[0017] (2) The present invention only uses permanent magnets and magnetic conductor structures. Compared with equipment that requires electromagnetic auxiliary control, it avoids the heating phenomenon and energy loss caused by magnetic circuit coupling and simplifies the process flow. Compared with magnetic needles using micro-engraving technology or grinding wheel cutting technology, the magnetic powder filling technology is used to avoid complex processing processes, reduce process difficulty and processing time, avoid being affected by cutting forces during processing, and improve structural performance. The top of the produced magnetic needle is sealed with epoxy glue to form a natural protective layer to prevent the magnetic needle from being damaged by pressure or friction. The bad magnetic needle can also be detected and repaired, which improves the accuracy and reliability of the equipment.

[0018] (3) The present invention can also adjust the size and spacing of the magnetic needles to match the gravity of chips of different sizes and chip substrates of different specifications, thereby achieving large-scale, high-precision mass transfer with high efficiency and low cost, and is particularly suitable for mass transfer of Micro LED chips.

[0019] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of a large-area dense array of magnetic powder needles in an embodiment of the present invention; Figure 2 A three-dimensional diagram of a large-area dense array of magnetic powder needles in an embodiment of the present invention; Figure 3 Schematic diagram of the permanent magnet layer structure of an embodiment of the present invention; Figure 4 Schematic diagram of the magnetic conductive layer structure of an embodiment of the present invention; Figure 5 It is a schematic diagram of the structure of the magnetic needle seat layer before processing according to an embodiment of the present invention; Figure 6 It is a schematic diagram of the structure of the magnetic needle seat layer after processing according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of the magnetic needle tip layer before processing according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the structure of the magnetic needle tip layer before processing according to an embodiment of the present invention; Fig. 9A schematic diagram of the magnetic flux density of a permanent magnetic field according to an embodiment of the present invention; Fig.10 A schematic diagram of magnetic force distribution on a chip according to an embodiment of the present invention; Reference numerals: 1. Permanent magnet layer; 2. Magnetic conductor layer; 3. Magnetic needle seat layer; 4. Magnetic needle tip layer; 5. Magnetic needle seat; 6. Magnetic needle tip; 7. Positioning pin. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0023] Example like Figure 1-Figure 8 As shown, the present invention provides a large-area dense array magnetic needle, comprising a permanent magnet layer 1, a magnetic conductive layer 2, a magnetic needle seat layer 3, and a magnetic needle tip layer 4 connected in sequence by a positioning pin 7, the four of which are tightly fitted, the permanent magnet layer 1 is arranged at the bottom, the magnetic conductive layer 2 is located above the permanent magnet layer 1, the magnetic needle seat layer 3 is located above the magnetic conductive layer 2, and the magnetic needle tip layer 4 is located above the magnetic needle seat layer 3, and the four are tightly fitted; the material of the permanent magnet layer 1 is one or more of aluminum-nickel permanent magnet alloy, iron-chromium-cobalt permanent magnet alloy, permanent magnet ferrite, rare earth permanent magnet and composite permanent magnet material, the length of the permanent magnet layer 1 is 200~300mm, the width is 200~300mm, and the height is 10~20mm. The material of the magnetic conductive layer 2 is one or more of industrial pure iron, cobalt-iron alloy, nickel-iron alloy, ferrite and ferrite. The magnetic conductive layer 2 has a length of 200-300 mm, a width of 200-300 mm and a height of 1-5 mm.

[0024] The materials of the magnetic needle seat layer 3 and the magnetic needle tip layer 4 are one or more of pure aluminum and plastic with zero magnetic permeability. The length of the magnetic needle seat layer 3 is 200~300mm, the width is 200~300mm, and the height is 0.5~1mm; a plurality of needle seat positioning holes are arranged in an array on the magnetic needle seat layer 3. The length of the magnetic needle tip layer 4 is 200~300mm, the width is 200~300mm, and the height is 0.1~0.2mm. A plurality of needle tip positioning holes are arranged in an array on the magnetic needle tip layer 4. The needle seat positioning hole and the needle tip positioning hole are arranged oppositely. After installation, the centers of the needle seat positioning hole and the needle tip positioning hole coincide with each other. The diameter of the needle seat positioning hole is 0.3~0.5mm, and the spacing is 1~2mm; the diameter of the needle tip positioning hole is 0.1~0.2mm, and the spacing is 1~2mm.

[0025] A plurality of magnetic needle seats 5 are arranged in an array on the magnetic needle seat layer 3. The magnetic needle seats 5 are formed by filling part of the magnetic powder in the seat positioning holes. After the filling is completed, they are all sealed and fixed by epoxy glue. The diameter of the formed magnetic needle seats 5 is 0.3~0.5mm, and the spacing between two adjacent magnetic needle seats 5 is 1~2mm.

[0026] A plurality of magnetic needle tips 6 are arranged in an array on the magnetic needle tip layer 4. The magnetic needle tips 6 are formed by filling a portion of magnetic powder in the needle tip positioning hole. After the filling is completed, they are all sealed and fixed by epoxy glue. The diameter of the formed magnetic needle tips 6 is 0.1-0.2 mm, and the spacing between two adjacent magnetic needle tips 6 is 1-2 mm. The formed magnetic needle seat 5 is arranged concentrically with the magnetic needle tip 6.

[0027] The magnetic powders used for the magnetic needle base 5 and the magnetic needle tip 6 are high magnetic permeability, low coercive force, and low remanent magnetization particles with a diameter of 10-20 nm. The materials are one or more of industrial pure iron, cobalt-iron alloy, nickel-iron alloy, ferrite, and ferrite. When densely stacked, they can uniformly transmit the magnetic field.

[0028] A plurality of positioning pin holes are arranged on the permanent magnet layer 1 , the magnetic conductive layer 2 , the magnetic needle seat layer 3 , and the magnetic needle tip layer 4 , and the positioning pin holes and the positioning pins 7 are used to fix the four.

[0029] The method for manufacturing the large-area dense array of magnetic needles comprises the following steps: S1. Prepare the permanent magnet layer 1, the magnetic conductive layer 2, the magnetic needle seat layer 3, and the magnetic needle tip layer 4 according to the design requirements, and process 7 holes for the positioning pins; the permanent magnet layer 1 is obtained by injection molding or sintering, and the magnetic conductive layer 2, the magnetic needle seat layer 3, and the magnetic needle tip layer 4 are all obtained by rolling, stretching, cutting or injection molding; S2, processing a plurality of needle seat holes distributed in an array on the magnetic needle seat layer 3, and processing a plurality of needle tip holes distributed in an array on the magnetic needle tip layer 4, wherein the positions of the needle tip holes correspond to the needle seat holes; S3, move the magnetic needle seat layer 3 to the top of the glass plate, apply a small amount of epoxy glue on the surface of the needle seat hole to seal the top, turn it over after solidification, add lubricant into the needle seat hole, mix the magnetic powder and additives into a slurry, fill it into the needle seat hole from top to bottom, mold it in an axial directional magnetic field, and then inject epoxy glue from the top to the inside to fill the gap and seal the top, and completely fix it to form a magnetic needle seat 5; S4, processing a magnetic needle tip 6 on the magnetic needle tip layer 4 according to the operation in S3; S5. Mechanically position the permanent magnet layer 1, the magnetic conductive layer 2, the magnetic needle seat layer 3, and the magnetic needle tip layer 4 through the positioning pin 7 holes. After the installation is completed, use a precision Gauss meter to measure the magnetic density above the magnetic needle array to ensure that the magnetic field density meets the requirements and obtain a large-area dense array of magnetic powder needles.

[0030] like Figure 9-10 As shown, the large-area dense array magnetic powder magnet obtained above is tested. The permanent magnetic field generated by the permanent magnetic layer passes through the magnetic conductive layer 2, the magnetic needle seat 5, and the magnetic needle tip 6, and then generates a permanent magnetic field on the upper surface of the magnetic needle tip layer 4 with peak and valley distribution in the horizontal and vertical directions. The peak value is greater than or equal to 50mT, and the valley value is less than or equal to 10mT.

[0031] Therefore, the present invention relates to a large-area dense array of magnetic needles and a manufacturing method thereof, which can realize low-cost processing of a large number of dense array magnetic needles by powder filling, can greatly reduce the manufacturing cost in the mass transfer process, and has a promoting effect on mass transfer and the promotion of Micro LED.

[0032] 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 large-area dense array of magnetic needles, characterized in that: It comprises a permanent magnet layer, a magnetic conductive layer, a magnetic needle seat layer and a magnetic needle tip layer which are sequentially connected by positioning pins. The permanent magnet layer is arranged at the bottom. A plurality of magnetic needle seats are arranged in an array on the magnetic needle seat layer. A plurality of magnetic needle tips are arranged in an array on the magnetic needle tip layer.

2. A large-area dense array magnetic needle according to claim 1, characterized in that: The material of the permanent magnet layer is one or more of aluminum-nickel permanent magnet alloy, iron-chromium-cobalt permanent magnet alloy, permanent magnet ferrite, rare earth permanent magnet and composite permanent magnet material. The length of the permanent magnet layer is 200-300 mm, the width is 200-300 mm, and the height is 10-20 mm.

3. The large-area dense array magnetic needle according to claim 1, characterized in that: The material of the magnetic conductive layer is one or more of industrial pure iron, cobalt-iron alloy, nickel-iron alloy, ferrite and ferrite. The length of the magnetic conductive layer is 200-300 mm, the width is 200-300 mm, and the height is 1-5 mm.

4. The large-area dense array magnetic needle according to claim 1, characterized in that: The materials of the magnetic needle seat layer and the magnetic needle tip layer are one or more of pure aluminum and plastic with zero magnetic permeability. The length of the magnetic needle seat layer is 200-300 mm, the width is 200-300 mm, and the height is 0.5-1 mm. The magnetic needle tip layer has a length of 200-300 mm, a width of 200-300 mm, and a height of 0.1-0.2 mm.

5. The large-area dense array magnetic needle according to claim 1, characterized in that: The materials of the magnetic needle base and the magnetic needle tip are one or more of industrial pure iron, cobalt-iron alloy, nickel-iron alloy, ferrite, and ferrite.

6. The large-area dense array magnetic needle according to claim 1, characterized in that: The magnetic needle seat is concentrically arranged with the magnetic needle tip, the diameter of the magnetic needle seat is 0.3-0.5 mm, and the spacing between two adjacent magnetic needle seats is 1-2 mm; The diameter of the magnetic needle tip is 0.1-0.2 mm, and the spacing between two adjacent magnetic needle tips is 1-2 mm.

7. The large-area dense array magnetic needle according to claim 1, characterized in that: The permanent magnet layer, the magnetic conductive layer, the magnetic needle seat layer, and the magnetic needle tip layer are all provided with a plurality of positioning pin holes.

8. A method for manufacturing a large-area dense array of magnetic needles according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Prepare the permanent magnet layer, the magnetic conductive layer, the magnetic needle seat layer, and the magnetic needle tip layer according to the design requirements, and process the positioning pin hole; S2, processing a plurality of needle seat holes distributed in an array on the magnetic needle seat layer, and processing a plurality of needle tip holes distributed in an array on the magnetic needle tip layer, wherein the positions of the needle tip holes correspond to the needle seat holes; S3, move the magnetic needle seat layer to the top of the glass plate, apply a small amount of epoxy glue on the surface of the needle seat hole to seal the top, turn it over after solidification, add lubricant into the needle seat hole, mix magnetic powder and additives into a slurry, fill it into the needle seat hole from top to bottom, mold it in an axial directional magnetic field, and then inject epoxy glue from the top to the inside to fill the gap and seal the top, and completely fix it to form a magnetic needle seat; S4, processing a magnetic needle tip on the magnetic needle tip layer according to the operation of S3; S5. Mechanically position the permanent magnet layer, magnetic conductive layer, magnetic needle seat layer, and magnetic needle tip layer through the positioning pin holes. After installation, use a precision Gauss meter to measure the magnetic density above the magnetic needle array to ensure that the magnetic field density meets the requirements and obtain a large-area dense array of magnetic powder needles.

9. The method for manufacturing a large-area dense array of magnetic needles according to claim 8, characterized in that: In the large-area dense array magnetic powder needle, the permanent magnetic field generated by the permanent magnetic layer passes through the magnetic conductive layer, the magnetic needle seat, and the magnetic needle tip to generate a permanent magnetic field with peak-valley distribution in both horizontal and vertical directions on the upper surface of the magnetic needle tip layer, with a peak value ≥50mT and a valley value ≤10mT.

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