Positioning electromagnetic magnetic needle device based on permanent magnet bias and application thereof

Abstract

The invention discloses a positioning electromagnetic magnetic needle device based on permanent magnet bias and application thereof, and relates to the technical field of chip mass transfer, the positioning electromagnetic magnetic needle device comprises a magnetic field generation system and a chip transfer system, the magnetic field generation system comprises permanent magnet steel, an electrified solenoid coil, a magnetic conductive layer and a magnetic conductive magnetic needle, the electrified solenoid coil surrounds the periphery of the permanent magnet steel, and the magnetic conductive layer is arranged on the periphery of the chip transfer system; the magnetic conductive layer is arranged on the upper surface of the permanent magnet steel, the magnetic conductive magnetic needles are uniformly distributed on the upper surface of the magnetic conductive layer in an array manner, the chip transfer system comprises a chip transfer substrate and a plurality of LED light-emitting chips, a plurality of welding spots are arranged on the transfer substrate and correspond to the magnetic conductive magnetic needles, and the LED light-emitting chips are provided with N-type nickel-plated electrode pins and P-type electrode pins. According to the positioning electromagnetic magnetic needle device based on permanent magnet bias and the application of the positioning electromagnetic magnetic needle device, the magnetic induction density of the magnetic conductive magnetic needle is accurately regulated and controlled by means of the magnetic field which is generated by the electrified solenoid coil and is opposite to the permanent magnetic field, and accurate fixing of a chip at a welding spot position of a transfer substrate is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of chip mass transfer, and particularly relates to a positioning electromagnetic needle device based on permanent magnet bias and its application. Background Art

[0002] The new generation of Mini / Micro LED display technology forms independent pixel points on the driving circuit board by thinning, miniaturizing, and matrixing LED devices, improving the light emission density of the display panel. Compared with traditional LCD and OLED, it has the advantages of high display brightness, large viewing angle, long service life, fast response speed, high contrast, and low power consumption, and is a new generation of display panel technology with great potential. The preparation of Mini / Micro LED display mainly includes the epitaxial growth of chip grains, the mass transfer of chips, the detection and repair of chips, etc. Among them, mass transfer is the key to the large-scale production of Mini / Micro LED displays. The mass transfer technology refers to picking up or peeling nearly hundreds of millions of Mini / Micro LED grains from the source substrate through a high-precision transfer device and transferring them to the target substrate through a high-speed and precise positioning mechanism.

[0003] The existing mainstream swing-arm type mass transfer scheme uses a robotic arm to pick up the chips on the crystal film and transfer the chips to the solder joint positions on the PCB board, which can better ensure the chip transfer quality and yield. However, in this scheme, the chip movement stroke is relatively large, the transfer process takes a long time, and the chip transfer efficiency is low.

[0004] A method and device for mass transfer of micro LEDs based on high-speed scanning laser transfer described in the authorized invention patent 202110019640.7 use the high-pressure gas generated by laser ablation of the crystal film to transfer the chips to the solder joint positions on the PCB board, achieving short-distance and rapid transfer of the chips, shortening the chip transfer time, and improving the transfer efficiency. However, in this scheme, there is a possibility of damaging the chips when laser ablating the polyimide of the crystal film, which limits the improvement of the transfer yield.

[0005] A mass transfer mechanism for Micro LEDs described in the authorized invention patent 202110574750.X uses the up-and-down reciprocating movement of a needle to quickly and precisely transfer the chips on the crystal film to the solder joint positions on the PCB board in a short distance, with relatively high transfer efficiency. However, the magnetic needle and the chip are not in flexible contact, which may damage the chips and limits the improvement of the chip transfer yield.

[0006] A manufacturing method of a display device and a display device described in the invention patent application 202111092474.X transfer chips to a target position using fluid, which has the advantages of fast and large-batch chip transfer. However, this solution depends on specific chip structures and transfer substrate structures, and after the chips are transferred to the target position, they still need to be further transferred to the solder joint positions on the PCB board, resulting in a long and difficult process flow and a reduction in the chip transfer yield.

[0007] A transfer device, a Micro-LED chip, and a transfer method described in the invention patent 201910036356.3 use the magnetic field generated by a current-controlled solenoid to adsorb chips and have the function of controlling the transfer of a single 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, which is likely to cause uneven magnetic field distribution and is difficult to achieve rapid and massive transfer of Mini / Micro chips. Summary of the Invention

[0008] The object of the present invention is to provide a positioning electromagnetic needle device based on permanent magnet bias and its application, which uses a current-carrying solenoid coil to generate a magnetic field opposite to the permanent magnet magnetic field to precisely control the magnetic induction density of the magnetic conduction needle, so as to achieve precise fixation of the chip at the solder joint position of the transfer substrate.

[0009] To achieve the above object, the present invention provides a positioning electromagnetic needle device based on permanent magnet bias, including a magnetic field generation system and a chip transfer system. The magnetic field generation system includes a permanent magnet, a current-carrying solenoid coil, a magnetic conduction layer, and magnetic conduction needles. The current-carrying solenoid coil surrounds the periphery of the permanent magnet. The magnetic conduction layer is arranged on the upper surface of the permanent magnet, and the magnetic conduction needles are evenly arranged in an array on the upper surface of the magnetic conduction layer. The chip transfer system includes a chip transfer substrate and a number of LED light-emitting chips. A number of solder joints are arranged on the transfer substrate, and the solder joints are arranged corresponding to the magnetic conduction needles. The LED light-emitting chips are provided with N-type nickel-plated electrode pins and P-type electrode pins.

[0010] Preferably, the current-carrying solenoid coil is energized with a direct current of 0.3 - 0.7 A, the number of turns of the coil is 400 - 600 turns, and the diameter is 0.1 - 0.5 mm.

[0011] Preferably, the height of the permanent magnet is 5 - 10 mm, and the thickness of the magnetic conduction layer is 0.1 - 1 mm.

[0012] Preferably, the material of the chip transfer substrate is glass, and the thickness is 0.3 - 0.5 mm.

[0013] Preferably, the magnetic flux density at the top of the magnetic conduction needle is 0.3 - 0.4 T, and the magnetic flux density at the position on the magnetic conduction layer without the magnetic conduction needle is zero.

[0014] Preferably, the material of the magnetic needle is one or more of low-carbon steel, Fe-Si alloy, Fe-Al alloy, Ni-Fe alloy, soft magnetic ferrite, and amorphous soft magnetic alloy.

[0015] Preferably, the diameter of the magnetic needle is 50 - 200 μm, the height is 0.5 - 1 mm, and the distance between adjacent magnetic needles is 0.5 - 1.25 mm.

[0016] Preferably, the N-type nickel-plated electrode pin includes a contact layer, a barrier layer, a solder layer, and a protective layer stacked from top to bottom.

[0017] An application of a positioning electromagnetic magnetic needle device based on permanent magnet bias, the specific steps are as follows:

[0018] S1. Prepare several LED light-emitting chips, perform nickel plating on the entire surface of the N-type nickel-plated electrode pins, and do not process the P-type electrode pins;

[0019] S2. Prepare magnetic needles through machining or chemical immersion plating process, and perform magnetic heat treatment on the magnetic needles to make them have a certain magnetic permeability;

[0020] S3. Place the LED light-emitting chips at the solder joint positions on the chip transfer substrate, place the chip transfer substrate above, and make the magnetic needles directly below the solder joint positions on the chip transfer substrate;

[0021] S4. The LED light-emitting chips move under the magnetic force of the magnetic needles, causing the N-type nickel-plated motor to move directly above the magnetic needles and be accurately positioned at the solder joint positions;

[0022] S5. Apply a flow field in the X direction to the chip transfer substrate and the LED light-emitting chips, so that the P-type electrode pins complete the chip attitude alignment under the action of the fluid.

[0023] Therefore, the present invention adopts a positioning electromagnetic magnetic needle device based on permanent magnet bias with the above structure and steps, and uses the vacuum evaporation plating process to perform nickel plating on the display chip, making it have high magnetic conductivity to meet the magnetic needle attraction requirements. By precisely controlling the magnitude of the magnetic density value of the magnetic needle with the magnetic field generated by "permanent magnet + electromagnetic", it is realized that the chip is only attracted and fixed above the magnetic needle, and the chip without a magnetic needle position is not attracted. Thus, the array magnetic needles can attract and fix the chips at high speed, in large quantities, and accurately, greatly improving the chip transfer efficiency and yield. Compared with the relatively mature needle-piercing type mass transfer equipment in the industry, the efficiency is increased by nearly a hundred times, and it is especially suitable for the mass transfer of Mini / Micro LED chips.

[0024] Next, through the drawings and embodiments, the technical solutions of the present invention will be further described in detail. Brief Description of the Drawings

[0025] Figure 1 This is a schematic structural diagram of an embodiment of a positioning electromagnetic magnetic needle device based on permanent magnet bias according to the present invention.

[0026] Figure 2 This is a schematic structural diagram of the N-type nickel-plated electrode pin of an embodiment of the present invention.

[0027] Figure 3 This is the magnetic flux density distribution diagram of the single permanent magnetic field of an embodiment of the present invention.

[0028] Figure 4 This is the magnetic flux density distribution diagram of the single electromagnetic magnetic field of an embodiment of the present invention.

[0029] Figure 5 This is the magnetic flux density distribution diagram of the permanent magnet and electromagnetic composite magnetic field of an embodiment of the present invention.

[0030] Figure 6 This is the force data diagram of the LED light-emitting chip of an embodiment of the present invention.

[0031] Figure 7 This is the chip transfer flow chart of an embodiment of the present invention.

[0032] Reference numerals

[0033] 1. Permanent magnet; 2. Energized solenoid coil; 3. Magnetic conduction layer; 4. Magnetic conduction magnetic needle; 5. Chip transfer substrate; 6. LED light-emitting chip; 7. N-type nickel-plated electrode pin; 701. Contact layer; 702. Barrier layer; 703. Solder layer; 704. Protective layer; 8. P-type electrode pin. Detailed implementation manners

[0034] The technical solutions of the present invention will be further described below with reference to the drawings and embodiments.

[0035] Embodiment

[0036] As Figure 1 shown, a positioning electromagnetic magnetic needle device based on permanent magnet bias includes a magnetic field generating system and a chip transfer system. The magnetic field generating system includes a permanent magnet 1, an energized solenoid coil 2, a magnetic conduction layer 3 and a magnetic conduction magnetic needle 4. The energized solenoid coil 2 surrounds the periphery of the permanent magnet 1. The magnetic conduction layer 3 is disposed on the upper surface of the permanent magnet 1. The magnetic conduction magnetic needles 4 are uniformly arranged in an array on the upper surface of the magnetic conduction layer 3. The energized solenoid coil 2 is energized with a direct current of 0.3 - 0.7 A, the number of turns of the coil is 400 - 600 turns, and the diameter is 0.1 - 0.5 mm. The height of the permanent magnet 1 is 5 - 10 mm, and the thickness of the magnetic conduction layer 3 is 0.1 - 1 mm.

[0037] The magnetic flux density at the top of the magnetic needle 4 is 0.3 - 0.4 T, and the magnetic flux density at the position of the magnetic needle 4 on the magnetic conductive layer 3 is close to zero. Therefore, there is no magnetic adsorption force at the gap position between the two magnetic needles 4, avoiding the problem of the chip being blindly adsorbed. The material of the magnetic needle 4 is one or more of low-carbon steel, iron-silicon alloy, iron-aluminum alloy, nickel-iron alloy, soft magnetic ferrite, and amorphous soft magnetic alloy. The diameter of the magnetic needle 4 is 50 - 200 μm, the height is 0.5 - 1 mm, and the distance between adjacent magnetic needles 4 is 0.5 - 1.25 mm.

[0038] The chip transfer system includes a chip transfer substrate 5 and several LED light-emitting chips 6. There are several solder joints arranged on the chip transfer substrate 5, and the solder joints are arranged corresponding to the magnetic needles 4. The LED light-emitting chip 6 is provided with an N-type nickel-plated electrode pin 7 and a P-type electrode pin. The material of the chip transfer substrate 5 is glass, and the thickness is 0.3 - 0.5 mm.

[0039] As Figure 2 shown, the N-type nickel-plated electrode pin 7 includes a contact layer 701, a barrier layer 702, a solder layer 703, and a protective layer 704 stacked from top to bottom. Among them, the main component of the contact layer 701 is a Ti / Al mixture, and the thickness is about 0.5 μm; the main component of the barrier layer 702 is a Pt / Ni mixture, and the thickness is about 1 μm; the main component of the solder layer 703 is a SnAgCu mixture, and the thickness is about 8 μm; the main component of the protective layer 704 is Au, and the thickness is about 0.05 μm.

[0040] An application of a positioning electromagnetic needle device based on permanent magnet bias, as Figure 7 shown, the specific steps are as follows:

[0041] S1. Prepare several LED light-emitting chips 6, and perform full-surface nickel plating on the barrier layer 702 in the N-type nickel-plated electrode pin 7. When the layer thickness increases to 1 μm, the N-type nickel-plated electrode pin 7 has high magnetic conductivity, meeting the preparation conditions for the LED light-emitting chip 6 to be attracted. The other specifications of the LED light-emitting chip 6 are the same as those of ordinary display chips, and the nickel plating process will not have a negative impact on the display performance of the LED light-emitting chip 6. Continue to prepare the solder layer 703 outside the barrier layer 702 to enhance the conductivity of the N-type nickel-plated electrode pin 7, and prepare the protective layer 704 outside the solder layer 703 to protect the pin. The P-type electrode pin 8 is prepared normally without additional treatment.

[0042] S2. Prepare the magnetic needle 4 through machining or chemical immersion plating process, and perform magnetic heat treatment on the magnetic needle 4 to make it have high magnetic permeability.

[0043] S3. Place the LED light-emitting chip 6 at the solder joint position on the chip transfer substrate 5. Place the chip transfer substrate 5 above, and position the magnetic needle 4 directly below the solder joint position on the chip transfer substrate 5.

[0044] S4. The LED light-emitting chip 6 moves under the magnetic force of the magnetic needle 4, causing the N-type nickel-plated motor to move directly above the magnetic needle 4 and accurately position it at the solder joint position. The magnetic field direction generated by the permanent magnet is N at the top and S at the bottom, and its magnetic flux density distribution is as Figure 3 shown. The magnetic field direction generated by the energized solenoid coil 2 is S at the top and N at the bottom, and its magnetic flux density distribution is as Figure 4 shown. The magnetic flux density value of the electromagnetic magnetic field is less than that of the permanent magnetic field. The magnetic flux density distribution of the permanent and electromagnetic composite magnetic field is as Figure 5 shown. The magnetic field generating device generates a uniform magnetic field and conducts it to the position of the magnetic needle 4 through the magnetic conductive layer 3. Therefore, the magnetic field at the upper end of the magnetic needle 4 can be accurately regulated by linearly controlling the current, thereby further controlling the adsorption force of the magnetic needle 4 on the nickel-plated LED chip, that is, the force on the light-emitting LED chip in the composite magnetic field, as Figure 6 shown. Its curve coincides with the magnetic flux density distribution curve in Figure 5 .

[0045] S5. Apply a flow field in the X direction to the chip transfer substrate 5 and the LED light-emitting chip 6, so that the P-type electrode pin 8 completes the chip attitude alignment under the action of the fluid.

[0046] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions of the present invention or make equivalent replacements, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A positioning electromagnetic needle device based on permanent magnetic bias, characterized by: It includes a magnetic field generating system and a chip transfer system. The magnetic field generating system includes a permanent magnet, an energized spiral coil, a magnetic conductive layer and a magnetic conductive needle. The energized spiral coil surrounds the periphery of the permanent magnet, the magnetic conductive layer is arranged on the upper surface of the permanent magnet, and the magnetic conductive needles are evenly distributed in an array on the upper surface of the magnetic conductive layer. The chip transfer system includes a chip transfer substrate and several LED light-emitting chips. Several solder joints are arranged on the transfer substrate, and the solder joints are arranged corresponding to the magnetic conductive needles. The LED light-emitting chip is provided with N-type nickel-plated electrode pins and P-shaped electrode pins.

2. The positioning electromagnetic needle device based on permanent magnetic bias according to claim 1, characterized in that: The energized solenoid coil is supplied with a direct current of 0.3-0.7A, has 400-600 turns, and has a diameter of 0.1-0.5mm.

3. The positioning electromagnetic needle device based on permanent magnetic bias according to claim 1, characterized in that: The height of the permanent magnet steel is 5-10 mm, and the thickness of the magnetic conductive layer is 0.1-1 mm.

4. The positioning electromagnetic needle device based on permanent magnetic bias according to claim 1, characterized in that: The chip transfer substrate is made of glass with a thickness of 0.3-0.5mm.

5. The positioning electromagnetic needle device based on permanent magnetic bias according to claim 1, characterized in that: The magnetic flux density at the top of the magnetic needle is 0.3-0.4T, and the magnetic flux density at the position without the magnetic needle on the magnetic layer is zero.

6. The positioning electromagnetic needle device based on permanent magnetic bias according to claim 1, characterized in that: The material of the magnetic needle is one or more of low carbon steel, iron-silicon alloy, iron-aluminum alloy, nickel-iron alloy, soft ferrite and amorphous soft magnetic alloy.

7. The positioning electromagnetic needle device based on permanent magnetic bias according to claim 1, characterized in that: The diameter of the magnetic needle is 50-200 μm, the height is 0.5-1 mm, and the spacing between adjacent magnetic needles is 0.5-1.25 mm.

8. The positioning electromagnetic needle device based on permanent magnetic bias according to claim 1, characterized in that: The N-type nickel-plated electrode pin includes a contact layer, a barrier layer, a solder layer and a protective layer stacked from top to bottom.

9. Application of a positioning electromagnetic needle device based on permanent magnetic bias according to any one of claims 1 to 8, characterized in that: The specific steps are as follows: S1. Prepare several LED light-emitting chips, perform nickel plating on the entire surface of the N-type nickel-plated electrode pins, and do not perform nickel plating on the P-type electrode pins; S2. preparing a magnetic needle by machining or chemical immersion plating, and performing magnetic heat treatment on the magnetic needle to make it have a certain magnetic permeability; S3. Place the LED light-emitting chip at the soldering point on the chip transfer substrate, and place the chip transfer substrate on top so that the magnetic needle is directly below the soldering point on the chip transfer substrate; S4. The LED light-emitting chip moves under the magnetic force of the magnetic needle, causing the N-type nickel-plated motor to move directly above the magnetic needle and accurately locate the soldering point. S5. Apply an X-direction flow field to the chip transfer substrate and the LED light-emitting chip, so that the P-type electrode pins can complete the chip posture correction under the action of the fluid.

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