Self-decoupling electromagnetic device for chip mass transfer based on permanent magnet bias and application

Abstract

The invention discloses a self-decoupling electromagnetic device for chip mass transfer based on permanent magnet bias and application thereof, and relates to the technical field of chip mass transfer, the self-decoupling electromagnetic device comprises a coil supporting seat, a magnetic needle fixing base, a magnetic needle supporting cover and an electromagnetic supporting cover, and the center of the top surface of the coil supporting seat is provided with a magnetic needle accommodating groove; the magnetic needle fixing base is arranged in the magnetic needle containing groove, an aluminum alloy bottom layer is arranged above the magnetic needle fixing base, a plurality of permanent magnet magnetic needles are arranged on the magnetic needle fixing base, the top ends of the permanent magnet magnetic needles upwards penetrate through the aluminum alloy bottom layer, a magnetic needle supporting cover is arranged around the magnetic needle containing groove, and an electromagnetic supporting cover is arranged on the periphery of the magnetic needle supporting cover. And an electrified solenoid coil is arranged between the magnetic needle supporting cover and the electromagnetic supporting cover. According to the self-decoupling electromagnetic device for chip mass transfer based on permanent magnet bias and the application of the self-decoupling electromagnetic device, rapid mass accurate transfer of Mini / Micro LED chips is achieved in a fluid field and magnetic field combined mode.

Description

Technical Field

[0001] The present invention relates to the technical field of chip mass transfer, and in particular to a self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias and application thereof. Background Art

[0002] At present, there are four main precision grasping technologies used in the industry for mass transfer of Micro LED chips, namely, needle-piercing and swing-arm mass transfer technologies using mechanical motion, laser transfer technology using high-energy laser beams, and fluid assembly technology using fluid flow. Fluid assembly technology places Micro LEDs in a liquid suspension and uses fluid force to allow Micro LEDs to fall into corresponding wells on the substrate. The transfer speed is faster, the fluid can be reused, and the cost is lower. However, the movement of the chip in the fluid is irregular, difficult to control, and it is easy to damage the chip in a collision.

[0003] Among the many methods of implementing fluid assembly technology, fluid magnetic self-assembly transfer technology is an advanced technology based on microstructure templates and precise control, which can transfer a large number of tiny LED chips from the source substrate to the target substrate in a short time. This technology uses a microstructure template made of elastic polymer to form a micro-adsorption structure on the template that matches the LED chip array, and realizes the synchronous picking and precise positioning of a large number of chips through electrostatic adsorption or vacuum adsorption.

[0004] In the existing technology, the transfer device, Micro-LED crystal and transfer method described in the authorized invention patent 201910036356.3 use electric current to control the magnetic field generated by the solenoid to adsorb the chip, thereby achieving fixed attraction of the chip. However, this solution does not have the ability to transfer chips in an array, and the size of the solenoid coil is too large, resulting in excessive power consumption of the coil, making it difficult to achieve rapid and massive transfer of Mini / Micro chips. A massive transfer device and method described in the applied invention patent 202110493783.1 uses a permanent magnetic needle array to transfer LED chips in batches, and uses an electromagnetic encoder to capture and release the chips. The transfer efficiency is high and the transfer process is easy to control. However, the electromagnetic magnetic field of this solution passes through the permanent magnetic field, resulting in excessive power consumption of the coil, and is limited by the size of the permanent magnet, so it is impossible to accurately attract and fix small-sized chips, and it is difficult to ensure the chip transfer yield. Authorized invention patent 202110016028.4 A magnetic MicroLED mass transfer structure and method, which sets conductive materials and magnetic conductive layers on each LED chip pin, and then uses electromagnetic force to grasp and release the chip, with the characteristics of fast and large-scale chip transfer. However, this solution is limited by the electromagnetic suction force generated by small coils and small currents, making it difficult to fix the LED chip, reducing the yield of chip transfer. Application for invention patent 202311564639.8 A mass transfer method with magnetic alignment and fluid alignment, which uses electromagnetic needles to achieve batch attraction and fixation of LED chips, and then uses fluid to adjust the chip posture, which can achieve accurate pickup and release of chips, and can transfer chips in batches. However, the coil current required by the magnetic needle of this scheme is too large, which increases the power consumption of the electromagnetic needle, limits the use time of the chip transfer equipment, and reduces the chip transfer efficiency. Summary of the invention

[0005] The purpose of the present invention is to provide a self-decoupling electromagnetic device for mass chip transfer based on permanent magnetic bias and its application, which can realize rapid, large-scale and precise transfer of Mini / Micro LED chips by combining fluid field and magnetic field.

[0006] To achieve the above-mentioned purpose, the present invention provides a self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias, including a coil support seat, a magnetic needle fixing base, a magnetic needle support cover, and an electromagnetic support cover. A magnetic needle accommodating groove is arranged in the center of the top surface of the coil support seat, the magnetic needle fixing base is arranged in the magnetic needle accommodating groove, an aluminum alloy bottom layer is arranged above the magnetic needle fixing base, a plurality of permanent magnetic needles are arranged on the magnetic needle fixing base, and the top ends of the permanent magnetic needles pass upward through the aluminum alloy bottom layer. A magnetic needle support cover is arranged around the magnetic needle accommodating groove, an electromagnetic support cover is arranged on the periphery of the magnetic needle support cover, and a coil accommodating groove for placing an energized spiral coil is reserved between the magnetic needle support cover and the electromagnetic support cover.

[0007] Preferably, the permanent magnetic needle generates a permanent magnetic field, which is distributed on the XZ plane. When the energized spiral coil is energized, it generates an electromagnetic magnetic field, which is conducted from the air to the permanent magnetic needle. The electromagnetic magnetic field is distributed on the YZ plane. The permanent magnetic field and the electromagnetic magnetic field are perpendicular to each other. The electromagnetic magnetic field and the permanent magnetic field intersect at the top of the permanent magnetic needle, forming a self-decoupling electromagnetic magnetic field within the permanent magnetic field.

[0008] Preferably, the Micro-LED chip is arranged above the transfer substrate, a plurality of solder joints are arranged on the transfer substrate, the permanent magnetic needles are arranged corresponding to the solder joints, the Micro-LED chip has N-type nickel-plated electrode pins and P-type electrode pins, and the N-type nickel-plated electrode pins are pulled by the self-decoupling electromagnetic magnetic field in the permanent magnetic field.

[0009] Preferably, the magnetic flux density generated by the self-decoupling electromagnetic magnetic field in the permanent magnetic field at 0.5 mm above the permanent magnetic needle is 0.5-0.8 T, and the suction force on the N-type nickel-plated electrode pin is 0.0002-0.0005N.

[0010] Preferably, the material of the permanent magnetic needle is one or more of aluminum-nickel-cobalt permanent magnetic alloy, iron-chromium-cobalt permanent magnetic alloy, permanent magnetic ferrite, rare earth permanent magnetic material and composite permanent magnetic material. The diameter of the permanent magnetic needle is 0.5-1mm, the height is 1-5mm, and the distance between two permanent magnetic needles is 1.25-2.5mm.

[0011] Preferably, the material of the permanent magnetic support cover and the electromagnetic support cover is one or more of polyimide, polyphenylene sulfide, polysulfone, aromatic polyamide, polyarylate, polyphenylene ester, polyaryletherketone, liquid crystal polymer, and fluororesin.

[0012] Preferably, the power supply used by the energized solenoid coil is a bipolar four-quadrant power supply, the power supply output voltage is 10-12V, the voltage stability is 0.5%, and the current accuracy is 0.5%.

[0013] Preferably, a 0.1A direct current is passed through the energized spiral coil, the power is 10W, the number of turns of the energized spiral coil is 100-200 turns, the coil diameter is 0.1-0.5mm, and the operating temperature is 20-25°C.

[0014] An application of a self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias, the steps are as follows:

[0015] S1. Prepare N-type nickel-plated electrode pins on the Micro-LED chip by chemical nickel plating. The nickel layer has a uniform thickness and a smooth surface, and the force-bearing surface is uniformly stressed during attraction.

[0016] S2, preparing an energized solenoid coil by a winding machine, the size of the energized solenoid coil being adapted to the size of the coil receiving slot, and connecting the energized solenoid coil to a bipolar four-quadrant power supply;

[0017] S3. Place the Micro-LED chip on the transfer substrate in the fluid field. The fluid makes the Micro-LED chip approach the solder joint. The magnetic fields formed by the permanent magnetic needle and the energized solenoid coil meet at the top of the permanent magnetic needle, generating suction on the N-type nickel-plated electrode pin of the Micro-LED chip, so that the Micro-LED chip stays at the solder joint position directly above the permanent magnetic needle.

[0018] S4, adjusting the fluid velocity in the fluid field according to the posture of the Micro-LED chip, flushing the Micro-LED chip to make it straight, and forming a chip array;

[0019] S5. Take out the transfer substrate carrying the chip array, and weld the Micro-LED chip as a whole to the transfer substrate by welding.

[0020] Therefore, the present invention adopts the above-mentioned structure and steps to develop a self-decoupling electromagnetic device for mass chip transfer based on permanent magnetic bias and its application, utilizes the superposition of permanent magnetic field and electromagnetic magnetic field to achieve precise absorption of LED chips, and achieves decoupling between the two magnetic fields by setting magnetic circuits in different directions. Through a small current, low-cost and high-efficiency control can be achieved to realize batch attraction of fixed LED chips to the solder joint positions of the PCB board by the array magnetic needles, and then the chip posture is adjusted by fluid flushing to form a chip array, and the rapid and precise transfer of Mini / Micro LED chips in large quantities is achieved by combining fluid field and magnetic field.

[0021] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the XZ plane structure of an embodiment of a self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias according to the present invention;

[0023] Figure 2 A schematic diagram of the XY plane structure of an embodiment of the present invention;

[0024] Figure 3 Magnetic field density distribution diagram of a single permanent magnetic field according to an embodiment of the present invention;

[0025] Figure 4 is a magnetic field density distribution diagram of a single electromagnetic magnetic field according to an embodiment of the present invention;

[0026] Figure 5 A magnetic field density distribution diagram of a self-decoupling electromagnetic magnetic field in a permanent magnetic field according to an embodiment of the present invention;

[0027] Figure 6 FIG. 1 is a diagram showing the force data of a Micro-LED chip according to an embodiment of the present invention.

[0028] Reference numerals

[0029] 1. Coil support seat; 2. Electromagnetic support cover; 3. Magnetic needle fixing base; 4. Magnetic needle support cover; 5. Magnetic needle receiving slot; 6. Powered spiral coil; 7. Aluminum alloy bottom layer; 8. Transfer substrate; 9. Permanent magnetic needle; 10. Micro-LED chip; 11. P-type electrode pin; 12. N-type nickel-plated electrode pin. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0031] Example

[0032] like Figure 1 As shown, a self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias includes a coil support base 1, a magnetic needle fixing base 3, a magnetic needle support cover 4, and an electromagnetic support cover 2. A magnetic needle accommodating groove 5 is arranged in the center of the top surface of the coil support base 1, the magnetic needle fixing base 3 is arranged in the magnetic needle accommodating groove 5, an aluminum alloy bottom layer 7 is arranged above the magnetic needle fixing base 3, and a plurality of permanent magnetic needles 9 are arranged in an array on the magnetic needle fixing base 3, and the top of the permanent magnetic needle 9 passes through the aluminum alloy bottom layer 7 upward.

[0033] like Figure 2 As shown, a magnetic needle support cover 4 is arranged around the magnetic needle receiving groove 5, and an electromagnetic support cover 2 is arranged on the periphery of the magnetic needle support cover 4. A coil receiving groove for placing the energized spiral coil 6 is reserved between the magnetic needle support cover 4 and the electromagnetic support cover 2. The power supply used by the energized spiral coil 6 is a bipolar four-quadrant power supply, the power output voltage is 10-12V, the voltage stability is 0.5%, and the current accuracy is 0.5%. The energized spiral coil 6 is fed with 0.1A direct current, the power is 10W, the number of coil turns of the energized spiral coil 6 is 100-200 turns, the coil diameter is 0.1-0.5mm, and the working temperature is 20-25℃.

[0034] The permanent magnetic needle 9 generates a permanent magnetic field, which is distributed on the XZ plane. The magnetic flux density distribution of a single electromagnetic magnetic field is as follows: Figure 3 As shown. When the energized solenoid coil 6 is energized, an electromagnetic magnetic field is generated, and the distribution of the single electromagnetic field is shown in Figure 4. The electromagnetic magnetic field is conducted from the air to the permanent magnetic needle 9, and the electromagnetic magnetic field is distributed on the YZ plane. The permanent magnetic field and the electromagnetic magnetic field are perpendicular to each other, complementary to each other, and meet at the top of the permanent magnetic needle 9, forming a self-decoupling electromagnetic magnetic field in the permanent magnetic field.

[0035] The Micro-LED chip 10 is arranged above the transfer substrate 8, and a number of solder joints are arranged on the transfer substrate 8. The permanent magnetic needle 9 is arranged corresponding to the solder joints. The Micro-LED chip 10 has an N-type nickel-plated electrode pin 12 and a P-type electrode pin 11. The N-type nickel-plated electrode pin 12 is pulled by the self-decoupling electromagnetic magnetic field in the permanent magnetic field. The magnetic density generated by the self-decoupling electromagnetic magnetic field in the permanent magnetic field is 0.5-0.8T at 0.5mm above the permanent magnetic needle 9, and the suction force on the N-type nickel-plated electrode pin 12 is 0.0002-0.0005N, which is approximately equal to the gravity of the Micro-LED chip 10, so that only one chip can be sucked to avoid chip accumulation.

[0036] The material of the permanent magnetic needle 9 is one of aluminum-nickel-cobalt permanent magnetic alloy, iron-chromium-cobalt permanent magnetic alloy, permanent magnetic ferrite, rare earth permanent magnetic material and composite permanent magnetic material. The diameter of the permanent magnetic needle 9 is 0.5-1mm, the height is 1-5mm, and the distance between the two permanent magnetic needles 9 is 1.25-2.5mm.

[0037] The material of the magnetic needle support cover 4 and the electromagnetic support cover 2 is one of polyimide, polyphenylene sulfide, polysulfone, aromatic polyamide, polyarylate, polyphenyl ester, polyaryletherketone, liquid crystal polymer, and fluororesin, and has insulation properties.

[0038] An application of a self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias, the steps are as follows:

[0039] S1. Prepare N-type nickel-plated electrode pins 12 on the Micro-LED chip 10 by chemical nickel plating. The nickel layer has a uniform thickness and a smooth surface, and the force-bearing surface is uniformly stressed during attraction.

[0040] S2, preparing the energized solenoid coil 6 by a winding machine, the size of the energized solenoid coil 6 is adapted to the size of the coil receiving slot, and connecting the energized solenoid coil 6 to a bipolar four-quadrant power supply;

[0041] S3, placing the Micro-LED chip 10 in the fluid field, and using the fluid to bring the Micro-LED chip 10 close to the solder joint, the magnetic field formed by the permanent magnetic needle 9 and the energized spiral coil 6 intersects at the top of the permanent magnetic needle 9, and the magnetic density distribution is as follows: Figure 5 The composite magnetic field generates a suction force on the N-type nickel-plated electrode pin 12 of the Micro-LED chip 10, and the suction force distribution is shown in Figure 6 As shown, along the horizontal direction of the transfer substrate 8, the composite magnetic field's suction force on the Micro-LED chip 10 intermittently presents peaks and troughs, and the peak position indicates the soldering point position, thereby causing the Micro-LED chip 10 to stay at the soldering point position directly above the permanent magnetic needle 9.

[0042] S4, adjusting the fluid velocity in the fluid field according to the posture of the Micro-LED chip 10, flushing the Micro-LED chip 10 to make it straight, and forming a chip array;

[0043] S5. Take out the transfer substrate 8 carrying the chip array, and weld the Micro-LED chip 10 as a whole to the transfer substrate 8 by welding.

[0044] Therefore, the present invention adopts a self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias and its application of the above structure, and utilizes the non-coupling superposition of permanent magnetic field and electromagnetic magnetic field. Compared with the traditional swing arm or acupuncture mechanical LED chip mass transfer method, the array magnetic needle can accurately pick up and release tens of thousands of chips at a time, which greatly improves the efficiency of chip transfer and ensures the yield of chip transfer. Compared with the existing electromagnetic magnetic needle solution, only a very small current is required to have high magnetic conductivity, meet the magnetic needle attraction requirements, require less coils, low preparation cost, low operating power, and low energy loss. At the same time, the magnetic field generated by the small current is easy to control and has high precision. It can accurately control the size of the magnetic density value of the magnetic needle, so that the chip is only attracted and fixed above the magnetic needle, and the chip without the magnetic needle is not attracted. Only one chip is attracted above a magnetic needle to avoid chip stacking, thereby completing the high-speed, large-scale, and accurate attraction and fixing of chips by the array magnetic needle. The present invention greatly improves the chip transfer efficiency and yield, significantly reduces the cost of equipment manufacturing and operation, and is particularly suitable for the mass transfer of Mini / Micro LED chips.

[0045] 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 self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias, characterized in that: It includes a coil support seat, a magnetic needle fixing base, a magnetic needle supporting cover, and an electromagnetic supporting cover. A magnetic needle accommodating groove is arranged in the center of the top surface of the coil support seat, the magnetic needle fixing base is arranged in the magnetic needle accommodating groove, an aluminum alloy bottom layer is arranged above the magnetic needle fixing base, and a plurality of permanent magnetic needles are arranged on the magnetic needle fixing base. The top ends of the permanent magnetic needles pass through the aluminum alloy bottom layer upward. A magnetic needle supporting cover is arranged around the magnetic needle accommodating groove, an electromagnetic supporting cover is arranged on the periphery of the magnetic needle supporting cover, and a coil accommodating groove for placing an energized spiral coil is reserved between the magnetic needle supporting cover and the electromagnetic supporting cover.

2. The self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias according to claim 1, characterized in that: The permanent magnetic needle generates a permanent magnetic field, which is distributed on the XZ plane. When the energized spiral coil is energized, an electromagnetic magnetic field is generated, which is conducted from the air to the permanent magnetic needle. The electromagnetic magnetic field is distributed on the YZ plane. The permanent magnetic field and the electromagnetic magnetic field are perpendicular to each other. The electromagnetic magnetic field and the permanent magnetic field intersect at the top of the permanent magnetic needle, forming a self-decoupling electromagnetic magnetic field within the permanent magnetic field.

3. The self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias according to claim 2, characterized in that: The Micro-LED chip is arranged above the transfer substrate, and a number of solder joints are arranged on the transfer substrate. The permanent magnetic needles are arranged corresponding to the solder joints. The Micro-LED chip has N-type nickel-plated electrode pins and P-type electrode pins. The N-type nickel-plated electrode pins are pulled by the self-decoupling electromagnetic magnetic field in the permanent magnetic field.

4. The self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias according to claim 3, characterized in that: The self-decoupling electromagnetic magnetic field in the permanent magnetic field generates a magnetic density of 0.5 to 0.8 T at 0.5 mm above the permanent magnetic needle, and the suction force on the N-type nickel-plated electrode pin is 0.0002 to 0.0005N.

5. The self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias according to claim 1, characterized in that: The material of the permanent magnetic needle is one or more of aluminum-nickel-cobalt permanent magnetic alloy, iron-chromium-cobalt permanent magnetic alloy, permanent magnetic ferrite, rare earth permanent magnetic material and composite permanent magnetic material. The diameter of the permanent magnetic needle is 0.5-1mm, the height is 1-5mm, and the distance between two permanent magnetic needles is 1.25-2.5mm.

6. The self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias according to claim 1, characterized in that: The material of the permanent magnetic support cover and the electromagnetic support cover is one or more of polyimide, polyphenylene sulfide, polysulfone, aromatic polyamide, polyarylate, polyphenyl ester, polyaryletherketone, liquid crystal polymer, and fluororesin.

7. The self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias according to claim 1, characterized in that: The power supply used by the energized solenoid coil is a bipolar four-quadrant power supply with an output voltage of 10 to 12V, a voltage stability of 0.5%, and a current accuracy of 0.5%.

8. The self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias according to claim 7, characterized in that: A direct current of 0.1A is passed through the energized spiral coil, the power is 10W, the number of turns of the energized spiral coil is 100 to 200 turns, the coil diameter is 0.1 to 0.5mm, and the operating temperature is 20 to 25°C.

9. Application of a self-decoupling electromagnetic device for chip mass transfer based on permanent magnetic bias according to any one of claims 1 to 8, characterized in that: Here are the steps: S1. Prepare N-type nickel-plated electrode pins on the Micro-LED chip by chemical nickel plating. The nickel layer has a uniform thickness and a smooth surface, and the force-bearing surface is uniformly stressed during attraction. S2, preparing an energized solenoid coil by a winding machine, the size of the energized solenoid coil being adapted to the size of the coil receiving slot, and connecting the energized solenoid coil to a bipolar four-quadrant power supply; S3. Place the Micro-LED chip on the transfer substrate in the fluid field. The fluid makes the Micro-LED chip approach the solder joint. The magnetic fields formed by the permanent magnetic needle and the energized solenoid coil meet at the top of the permanent magnetic needle, generating suction on the N-type nickel-plated electrode pin of the Micro-LED chip, so that the Micro-LED chip stays at the solder joint position directly above the permanent magnetic needle. S4, adjusting the fluid velocity in the fluid field according to the posture of the Micro-LED chip, flushing the Micro-LED chip to make it straight, and forming a chip array; S5. Take out the transfer substrate carrying the chip array, and weld the Micro-LED chip as a whole to the transfer substrate by welding.

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