Three-color LED chip flow magnetic mass transfer device and method based on square pit

Abstract

The invention provides a three-color LED chip flow magnetic mass transfer device and method based on square pits, and belongs to the semiconductor mass transfer technology, the three-color LED chip flow magnetic mass transfer device comprises a lower layer transfer substrate, an upper layer transfer substrate is arranged above the lower layer transfer substrate, the lower layer transfer substrate is provided with multiple groups of pixel point square pits, and the upper layer transfer substrate is provided with multiple groups of pixel point square pits. A plurality of groups of upper-layer substrate transfer square pits are formed in the upper-layer transfer substrate, the lower-layer transfer substrate is in contact with the upper-layer transfer substrate, array magnetic needles are arranged below the lower-layer transfer substrate, magnetic needle tips on the array magnetic needles are arranged right below the pixel point square pits, a magnetized LED chip is arranged above the upper-layer transfer substrate, and the magnetized LED chip is arranged right below the pixel point square pits. And the magnetized LED chip is arranged right above the transfer square pit of the upper substrate. According to the three-color LED chip flow magnetic mass transfer device and method based on the square pit, the problems that in the prior art, the upper limit of transfer accuracy and efficiency of chip mass transfer is low, and the posture of the transferred chip cannot be accurately controlled are solved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor mass transfer technology, and in particular to a device and method for mass transfer of magnetic flux of a three-color LED chip based on square pits. Background Art

[0002] Micro-LED display technology is considered a major breakthrough in the field of display technology due to its advantages such as high brightness, high contrast, high resolution and low power consumption. In order to achieve high-resolution and high-pixel density Micro-LED display screens, mass transfer technology is one of the key steps. This technology requires the efficient and precise transfer of millions of Micro-LED chips from the growth substrate to the target driving substrate. At present, mass transfer technology includes a variety of methods, such as laser lift-off technology, contact μTP technology, laser non-contact μTP technology and self-fluid assembly technology.

[0003] In the existing patent "CN202420284153.2 proposes a Micro LED chip mass transfer device", the magnetic adsorption principle is used to achieve the rapid positioning of the Micro LED chip and the matching of the grooves of the special substrate, realizing the self-assembly process. However, this technology faces the challenges of precise alignment and bonding technology. The patent does not mention the accuracy of chip transfer of the three primary colors of the pixel point. During the transfer process, it cannot guarantee that there are R, G, and B chips on each pixel point and the arrangement order of R, G, and B on the pixel point, and the transfer accuracy and efficiency upper limit are low. The existing patent "CN202211665819.0 proposes a magnetic LED chip transfer method" by adjusting the thickness of the magnetic film and accurately controlling the magnetic field strength to achieve accurate adsorption and transfer of LED core particles of different colors. However, the transfer of R, G, and B chips using only the interaction between the magnetic field and the magnetic chip lacks accuracy, and the transfer yield and repeatability need to be improved, and the posture of the transferred chip cannot be accurately controlled. The prior art "CN202310975987.8 provides a method for self-assembly and mass transfer of Micro-LED chips" achieves high-precision self-assembly of chips by designing red, green and blue Micro-LED chips of different shapes and electrode structures to match the bonding holes of a special substrate. However, this method has specific requirements for the tilt angle and dynamic friction coefficient of the substrate, which limits its scope of application and flexibility. In addition, the self-assembly process relies on the precise matching of chip shape and electrode structure, which increases the complexity and precision requirements of chip manufacturing, and the transfer yield and accuracy need to be improved.

[0004] Among the many mass transfer technologies, the fluid magnetic self-assembly technology has attracted much attention due to its unique fluid process. It uses fluid dynamics and magnetic principles to automatically position the Micro-LED chip to a predetermined position in the fluid. This technology not only improves the transfer efficiency, but also significantly improves the transfer accuracy, and is particularly suitable for the manufacture of large-area display devices. This technology can reduce the transfer cost and improve the transfer efficiency, and is particularly suitable for the manufacture of large-screen display devices. Therefore, the present invention provides a method for realizing mass and precise transfer of three-color LED chips using fluid magnetic technology, providing an efficient and reliable chip transfer solution for applications such as Micro LED displays. Summary of the invention

[0005] The purpose of the present invention is to provide a device and method for mass transfer of three-color LED chips based on square pits, which uses magnetic flux technology to achieve mass and precise transfer of three-color LED chips, providing an efficient and reliable chip transfer solution for applications such as Micro LED displays.

[0006] To achieve the above-mentioned purpose, the present invention provides a device and method for massive transfer of magnetic flux of three-color LED chips based on square pits, comprising a lower transfer substrate, an upper transfer substrate is arranged above the lower transfer substrate, a plurality of groups of pixel point square pits are provided on the lower transfer substrate, a plurality of groups of upper substrate transfer square pits are provided on the upper transfer substrate, the lower transfer substrate is in contact with the upper transfer substrate, an array of magnetic needles is arranged below the lower transfer substrate, the magnetic needle tips on the array of magnetic needles are arranged directly below the pixel point square pits, a magnetized LED chip is arranged above the upper transfer substrate, and the magnetized LED chip is arranged directly above the transfer square pits of the upper substrate.

[0007] Preferably, the pixel square pit is three side-by-side through holes, and the three through holes in the pixel square pit correspond to R, G, and B on a group of pixel points respectively.

[0008] Preferably, there are three types of transfer square pits in the upper substrate, the transfer square pit in the upper substrate is a single through hole, and the single through hole in the transfer square pit in the upper substrate is one of the pixel points R, G, and B.

[0009] Preferably, the thickness of the lower transfer substrate is 0.8 mm to 1 mm, and the thickness of the upper transfer substrate is 0.2 mm to 0.4 mm.

[0010] Preferably, the size of the pixel point square pit is consistent with the transfer square pit of the upper substrate, and the size of the pixel point square pit and the transfer square pit of the upper substrate is 15% larger than the size of the magnetic LED chip.

[0011] Preferably, the magnetic field generated by the array magnetic needles presents a peak-valley distribution in space, the peak value of the magnetic field is greater than or equal to 50 mT, and the peak-valley value of the magnetic field is less than or equal to 10 mT.

[0012] A method for mass transfer of magnetic flux from a three-color LED chip based on square pits, comprising: S1, preparing a plurality of magnetized LED chips and magnetizing the magnetized LED chips; S2, placing the lower transfer substrate in the flow field pool and fixing it; S3, placing the upper substrate on the lower substrate tightly and aligning the positions of the corresponding square pits; S4, placing the array magnetic needle under the flow field pool, and using a three-dimensional motion platform to adjust the spatial position of the array magnetic needle so that the needle tip of the array magnetic needle is aligned with the position of the square pit to be transferred; S5, place the magnetic LED chip, and then turn on the flow field; S6, adjusting the flow rate and the position of the array magnetic needle to allow the magnetized LED chip to be transferred into the pit; S7, after all the magnetic LED chips are put into the pit, close the flow field pool and take out the upper transfer substrate, and replace it with another upper transfer substrate; S8, repeat steps S3-S7 until the magnetized LED chips in the three square pits R, G, and B are transferred; S9, take out the lower transfer substrate, and complete the mass transfer after adding dots to the lower transfer substrate.

[0013] Preferably, the filling point adopts visual detection of the holes in the square pit, and uses a needle to fill the corresponding magnetic LED chip in the missing square pit.

[0014] Therefore, the present invention adopts the above-mentioned three-color LED chip magnetic flux mass transfer device and method based on square pits, and the technical effects are as follows: 1. By transferring through a double-layer board, the chip is transferred according to a specific R, G, B sequence, which improves the reliability of the transfer.

[0015] 2. Utilizing magnetic force to assist self-assembly, through specific magnetic needle design and magnetic field distribution, it ensures that the chip can be accurately captured and placed, improving the efficiency and speed of the assembly process. Precise magnetic force control and flow field adjustment help reduce errors in the assembly process and improve transfer yield.

[0016] 3. Strong compatibility, suitable for the transfer and assembly of RGB primary color chips, which helps to realize the application of full-color display technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of the upper transfer substrate of the present invention; Figure 2This is a schematic diagram of the structure of the lower transfer substrate of the present invention; Figure 3 This is a spatial structure diagram of the red upper transfer substrate and the lower transfer substrate of the present invention; Figure 4 It is a top view of the red upper transfer substrate and the lower transfer substrate after being combined with each other; Figure 5 It is a top view of the green upper transfer substrate and the lower transfer substrate after being combined with each other in the present invention; Figure 6 It is a top view of the blue upper transfer substrate and the lower transfer substrate after being combined with each other; Figure 7 This is a schematic diagram of an R-type chip entering a pit according to the present invention; Figure 8 This is a schematic diagram of removing the R-type upper transfer substrate of the present invention; Fig. 9 This is a schematic diagram of the lower substrate after the transfer of the present invention; Fig.10 The present invention discloses a flow chart of a transfer method.

[0018] Reference numerals 1. Lower transfer substrate; 101, pixel point square pit; 1011, lower R-type chip transfer square pit; 1012, lower G-type chip transfer square pit; 1013, lower B-type chip transfer square pit; 2. Upper transfer substrate; 201, upper substrate transfer square pit; 2011, upper R-type chip transfer square pit; 3. Array magnetic needle; 301, magnetic needle tip; 4. Magnetized LED chip. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0020] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0021] Embodiment 1 like Figure 1-Figure 3 As shown, the present invention provides a three-color LED chip magnetic flux mass transfer device based on square pits, including a lower transfer substrate 1, an upper transfer substrate 2 is arranged above the lower transfer substrate 1, a plurality of groups of pixel point square pits 101 are opened on the lower transfer substrate 1, a plurality of groups of upper substrate transfer square pits 201 are opened on the upper transfer substrate 2, the lower transfer substrate 1 is in contact with the upper transfer substrate 2, an array magnetic needle 3 is arranged below the lower transfer substrate 1, the magnetic needle needle tip 301 on the array magnetic needle 3 is arranged directly below the pixel point square pit 101, a magnetized LED chip 4 is arranged above the upper transfer substrate 2, and the magnetized LED chip 4 is arranged directly above the upper substrate transfer square pit 201.

[0022] The thickness of the lower transfer substrate 1 is 0.8mm~1mm, and the thickness of the upper transfer substrate 2 is 0.2mm~0.4mm. The lower transfer substrate 1 has multiple groups of pixel pits 101, each group of pixel pits 101 includes an R-type chip transfer pit 1011, a lower G-type chip transfer pit 1012, and a lower B-type chip transfer pit 1013; the upper transfer substrate 2 has multiple upper substrate transfer pits 201. The size of the pixel pit 101 is consistent with that of the upper substrate transfer pit 201, and the size of the pixel pit 101 and the upper substrate transfer pit 201 is 15% larger than the size of the magnetized LED chip 4.

[0023] like Figure 4-Figure 6 As shown, in Figure 4 It can be observed that the red upper transfer substrate 2 and the lower transfer substrate 1 are bonded. On the lower transfer substrate 1, only the lower R-type chip transfer square pit 1011 in each group of pixel square pits 101 is empty, so only the R-type chip can be transferred at this time. Figure 5 It can be observed in the figure that the green upper transfer substrate 2 and the lower transfer substrate 1 are bonded. On the lower transfer substrate 1, only the lower G-type chip transfer square pit 1012 in each group of pixel square pits 101 is empty, and only the G-type chip can be transferred at this time. Figure 6 It can be observed in the figure that the blue upper transfer substrate 2 and the lower transfer substrate 1 are bonded. On the lower transfer substrate 1, in each group of pixel square pits 101, only the lower B-type chip transfer square pit 1013 is a hole, and only B-type chips can be transferred at this time.

[0024] like Figure 7 As shown, the bottom layer is the array magnetic needle 3, and there are magnetic needle tips 301 on the array magnetic needle 3. The magnetic field generated by the array magnetic needle 3 is distributed in peaks and valleys in space, with a peak value greater than or equal to 50mT and a peak valley less than or equal to 10mT; in the middle are the tightly fitted red upper transfer substrate 2 and lower transfer substrate 1. The R-type magnetized LED chip 4 will roll into the square pit under the action of the fluid and the magnetic force, first pass through the upper R-type chip transfer square pit 211 and then enter the lower R-type chip transfer square pit 1011, and finally be attracted and fixed by the array magnetic needle 3; The upper magnetic pole of the magnetic needle is opposite to the magnetic pole of the chip pin layer. The chip will be caught by the magnetic needle and enter the groove due to the magnetic force. When the chip electrode side faces upward, the repulsive force generated by the same magnetic poles will prevent the chip from entering the pit and flip it until the chip electrode surface and the side with the magnetic powder layer face downward. It should be noted that the chip is a magnetic chip and should be magnetized before transfer.

[0025] like Figure 8-Figure 9As shown, when all R-type chips 4 are transferred, the upper R-type transfer substrate 2 is removed by the adsorption device, replaced with the upper G-type / B-type transfer substrate 2, and then the G-type / B-type chips are transferred. Until in the lower substrate 1, the lower R-type chip transfer square pit 1011, the lower G-type chip transfer square pit 1012, and the lower B-type chip transfer square pit 1013 are all occupied by the three types of R, G, and B chips; for the holes formed by a small number of chips that have not been transferred or have fallen off in the upper pit of the lower transfer substrate 1, the holes in the square pits are detected visually, and the magnetized LED chips 4 corresponding to the missing square pits are supplemented with a needle.

[0026] The size of the pixel point square pit 101 and the upper substrate transfer square pit 201 is 15% larger than the size of the magnetized LED chip 4. The device has no special requirements on the size of the transfer chip, and the three chips of R, G, and B are all common rectangular chips. The position of the square pit of the upper transfer substrate 2 can be changed at will, and the pixel arrangement of the lower transfer substrate 1 can be any arrangement of RGB, RBG, GRB, GBR, BRG, BGR, etc. when necessary.

[0027] like Fig.10 As shown, the present invention provides a method for transferring magnetic flux in a tri-color LED chip based on a square pit, comprising the following steps: S1, preparing a plurality of magnetized LED chips and magnetizing the magnetized LED chips; S2, placing the lower transfer substrate in the flow field pool and fixing it; S3, placing the upper substrate on the lower substrate tightly and aligning the positions of the corresponding square pits; S4, placing the array magnetic needle under the flow field pool, and using a three-dimensional motion platform to adjust the spatial position of the array magnetic needle so that the needle tip of the array magnetic needle is aligned with the position of the square pit to be transferred; S5, place the magnetic LED chip, and then turn on the flow field; S6, adjusting the flow rate and the position of the array magnetic needle to allow the magnetized LED chip to be transferred into the pit; S7, after all the magnetic LED chips are put into the pit, close the flow field pool and take out the upper transfer substrate, and replace it with another upper transfer substrate; S8, repeat steps S3-S7 until the magnetized LED chips in the three square pits R, G, and B are transferred; S9, take out the lower transfer substrate, and complete the mass transfer after adding dots to the lower transfer substrate.

[0028] It is worth noting that all chips that are not transferred in the solvent of the flow field pool can be recycled along with the solvent, reducing waste and transfer costs.

[0029] Therefore, the present invention adopts the above-mentioned three-color LED chip flow magnetic mass transfer device and method based on square pits, which includes a lower transfer substrate 1 and an upper transfer substrate 2. The lower transfer substrate 1 is provided with multiple groups of pixel point square pits 101 for accommodating magnetized LED chips 4 of corresponding colors, and the upper transfer substrate 2 is provided with multiple groups of upper substrate transfer square pits 201 for temporarily fixing the magnetized LED chips 4 to be transferred. By adjusting the position of the array magnetic needle 3 and the intensity of the magnetic field generated, the movement and positioning of the magnetized LED chip 4 in the flow field can be controlled so that it can accurately fall into the pixel point square pit 101 on the lower transfer substrate 1. The method includes the steps of making the magnetized LED chip 4, fixing the lower transfer substrate 1, placing the upper transfer substrate 2 and aligning the square pit position, adjusting the position of the array magnetic needle 3, opening the flow field, adjusting the flow rate and the magnetic needle orientation to allow the chip to enter the pit, closing the flow field and replacing the upper transfer substrate, repeating the steps until all color chips are transferred, and taking out the lower transfer substrate 1 for filling points. Among them, the dot filling step uses visual detection of the holes in the square pits and uses a needle to fill in the missing chips to ensure that the LED chip of the corresponding color is correctly placed in each pixel square pit.

[0030] 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 three-color LED chip magnetic flux mass transfer device based on square pits, characterized in that: It includes a lower transfer substrate, an upper transfer substrate is arranged above the lower transfer substrate, a plurality of groups of pixel point square pits are provided on the lower transfer substrate, a plurality of groups of upper substrate transfer square pits are provided on the upper transfer substrate, the lower transfer substrate is in contact with the upper transfer substrate, an array of magnetic needles is arranged below the lower transfer substrate, the magnetic needle tips on the array of magnetic needles are arranged directly below the pixel point square pits, a magnetized LED chip is arranged above the upper transfer substrate, and the magnetized LED chip is arranged directly above the upper substrate transfer square pits.

2. A three-color LED chip magnetic flux mass transfer device based on square pits according to claim 1, characterized in that: The pixel point square pit is three through holes arranged side by side, and the three through holes in the pixel point square pit correspond to R, G, and B on a group of pixel points respectively.

3. The device for transferring magnetic flux of three-color LED chips based on square pits according to claim 1, characterized in that: There are three types of transfer square pits in the upper substrate. The transfer square pit in the upper substrate is a single through hole. The single through hole in the transfer square pit in the upper substrate is one of the pixel points R, G, and B.

4. The device for transferring magnetic flux of three-color LED chips based on square pits according to claim 1, characterized in that: The thickness of the lower transfer substrate is 0.8 mm to 1 mm, and the thickness of the upper transfer substrate is 0.2 mm to 0.4 mm.

5. The device for mass transfer of magnetic flux from three-color LED chips based on square pits according to claim 1, characterized in that: The size of the pixel point square pit is consistent with the transfer square pit of the upper substrate, and the size of the pixel point square pit and the transfer square pit of the upper substrate is 15% larger than the size of the magnetic LED chip.

6. The device for transferring magnetic flux of three-color LED chips based on square pits according to claim 1, characterized in that: The magnetic field generated by the array magnetic needles presents a peak-valley distribution in space, the peak value of the magnetic field is greater than or equal to 50 mT, and the peak-valley value of the magnetic field is less than or equal to 10 mT.

7. A method for mass transfer of magnetic flux from a three-color LED chip based on square pits, characterized in that: include: S1, preparing a plurality of magnetized LED chips and magnetizing the magnetized LED chips; S2, placing the lower transfer substrate in the flow field pool and fixing it; S3, placing the upper substrate on the lower substrate tightly and aligning the positions of the corresponding square pits; S4, placing the array magnetic needle under the flow field pool, and using a three-dimensional motion platform to adjust the spatial position of the array magnetic needle so that the needle tip of the array magnetic needle is aligned with the position of the square pit to be transferred; S5, place the magnetic LED chip, and then turn on the flow field; S6, adjusting the flow rate and the position of the array magnetic needle to allow the magnetized LED chip to be transferred into the pit; S7, after all the magnetic LED chips are put into the pit, close the flow field pool and take out the upper transfer substrate, and replace it with another upper transfer substrate; S8, repeat steps S3-S7 until the magnetized LED chips in the three square pits R, G, and B are transferred; S9, take out the lower transfer substrate, and complete the mass transfer after adding dots to the lower transfer substrate.

8. The method for mass transfer of magnetic flux from a three-color LED chip based on square pits according to claim 7, characterized in that: The filling point adopts visual detection of the holes in the square pit, and uses a needle to fill the corresponding magnetic LED chip in the missing square pit.

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