A pneumatic mass transfer device and method based on a single-head multi-hole array

Abstract

The present invention discloses a pneumatic mass transfer device and method based on a single-head multi-hole array, which relates to the field of chip mass transfer technology. The device comprises a microporous substrate, a transfer head, a target substrate, and an adhesive body. The transfer head is arranged above the microporous substrate, which is arranged above the target substrate. A number of vertical through holes are evenly arranged on the microporous substrate. The adhesive body is bonded to the bottom surface of the microporous substrate. A number of chips to be transferred are bonded below the adhesive body. A number of solder joints are arranged above the target substrate, and adhesive particles are arranged at the solder joints. The adhesive particles are made of solder paste or conductive glue. The present invention adopts a pneumatic mass transfer device and method based on a single-head multi-hole array with the above structure and steps. The device and method can improve the efficiency and yield of mass transfer of Mini / Micro LED chips without damaging the substrate and chips or polluting the working environment, and conforms to the concept of green production safety.

Description

Technical Field

[0001] The present invention relates to the technical field of chip mass transfer, and in particular to a pneumatic mass transfer device and method based on a single-head multi-hole array. Background Art

[0002] In recent years, Mini / Micro LED display technology has emerged. Mini / Micro LED displays are composed of a large number of micron-level LED display chips that are independently packaged to form a single pixel. They have unparalleled advantages in luminous efficiency, power consumption, contrast, response speed, and lifespan. They are the best choice for the next generation of mainstream displays and are known as the "ultimate display technology of the 21st century."

[0003] The production process of Mini / Micro LED displays ranges from upstream processes such as wafer deposition, mask exposure, etching, PCB design, and gold wire flying, to midstream processes such as solder paste printing, mass transfer (MT), laser welding, and adhesive packaging, and then to downstream processes such as inter-board adjustment, full-page splicing, and TV packaging. These processes all affect production efficiency and costs. Mass transfer involves the precise and efficient transfer of millions or even tens of millions of micro LED chips from a source substrate to a target substrate. Even if 10,000 chips are transferred at a time, at least hundreds of repetitions are required. The number of transferred chips is huge, and the accuracy requirements are extremely high. Mass transfer has become a key link in the Mini / Micro LED packaging process that limits production capacity. Mass transfer technology directly affects the production speed, yield rate, and production cost of Mini / Micro LED displays, and is currently a key factor restricting the mass production of LED displays. There are many transfer methods in the world at present. The transfer methods actually used in production in the industry are mainly divided into two types: mechanical swing arm type and needle puncture type. The mechanical swing arm type is limited by its own structure and its production capacity is unable to be greatly improved. The needle puncture type transfer optimizes the transfer stroke and transfer structure, and uses needle puncture to drive the transfer to the chip. It has low requirements for film materials and does not require complex movements. It is the best alternative to the mechanical swing arm type and the only promising transfer method currently used in production.

[0004] In the existing technology, a chip transfer method, system and equipment described in patent application 202110109928.3 uses a push pin of a bonding head to pierce the blue film on the component ring, peel the chip from the blue film and transfer it to the substrate of the bonding table directly below. Due to the limitation of the transfer method, the push pin must pierce the light-emitting side of the chip to achieve the bonding of the chip electrode and the pad on the substrate. The light-emitting side of the chip is more fragile than the electrode side. Using a rigid needle to pierce the light-emitting side for transfer is bound to cause a large number of chips to be damaged, affecting the transfer efficiency and transfer yield.

[0005] The mass transfer mechanism of MicroLED described in patent application 202110574750.X adopts a top suction component to tighten a small range of chips on the transfer film, and drives a piercing arm with a leaf spring bearing or shrapnel driven by a voice coil motor to pierce the chip to achieve transfer. The control of its top suction component is complex, and some chips will inevitably be scratched and lost during the partial selection process. Although the piercing arm adopts an elastic device to eliminate some rigid contact, it still acts on the light-emitting side of the chip in the end. Under the working conditions of Micro LED chip transfer without a sapphire backing layer, more chips will be damaged, affecting the transfer.

[0006] The mass transfer method and equipment described in patent application 202210524975.9 adopts a needle-puncture transfer method. The target chip is transferred to the transfer film by needle-puncture. The chip on the transfer film is aligned with the pad and then press-welded. Finally, it is tested and repaired. Although this scheme can pierce the electrode side with higher relative strength, its rigid needle will scratch the electrode, affecting the service life of the product. In addition, the influencing factors in the two-step transfer process increase, which will affect the transfer efficiency and transfer yield.

[0007] The tracking and stabilizing distance pneumatic mass transfer device described in patent application 202310161990.6 uses tracking and stabilizing distance technology to ensure that the distance between the pneumatic actuator working position and the source substrate is always constant, eliminating the impact of fluctuations in the distance between the pneumatic actuator and the source substrate on the working gas, and achieving consistency in the gas state acting on the crystal film when the pneumatic mass transfer device transfers chips. However, the film material tension is insufficient, resulting in bubbles that rebound slowly, affecting the transfer efficiency.

[0008] The pneumatic needle-punching mass transfer device described in patent application 2023104732760 uses a needle-punching and pneumatic method to peel the chip from the crystal film to the target solder point. Needle-punching the blue film increases the tension of the film material, reduces the film material rebound time, and improves the transfer efficiency. Because the needle and the film material form a tiny enclosed space, the gas pressure at the needle head is increased, forming bubbles with better posture. However, the viscosity of the film material is difficult to control, which will cause some chips to be unable to be bonded by solder paste, affecting the transfer efficiency. Summary of the Invention

[0009] The purpose of the present invention is to provide a pneumatic mass transfer device and method based on a single-head multi-hole array, which can improve the efficiency and yield of mass transfer of Mini / Micro LED chips without damaging the substrate and chips, polluting the working environment, and complying with the concept of green production safety.

[0010] To achieve the above-mentioned objectives, the present invention provides a pneumatic mass transfer device based on a single-head multi-porous array, comprising a microporous substrate, a transfer head, a target substrate, and an adhesive body. The transfer head is arranged above the microporous substrate, the microporous substrate is arranged above the target substrate, a number of vertical through holes are evenly arranged on the microporous substrate, the adhesive body is bonded to the bottom surface of the microporous substrate, a number of chips to be transferred are bonded to the bottom of the adhesive body, a number of solder joints are arranged above the target substrate, and adhesive particles are arranged at the solder joints. The material of the adhesive particles is solder paste or conductive glue.

[0011] Preferably, the microporous substrate is fixed under the left vacuum suction cup and the right vacuum suction cup based on vacuum adsorption force.

[0012] Preferably, the adhesive body includes a first adhesive layer, an elastic layer and a second adhesive layer, the first adhesive layer is bonded to the bottom of the microporous substrate, the elastic layer is bonded to the bottom of the first adhesive layer, the second adhesive layer is bonded to the bottom of the elastic layer, and the chip to be transferred is bonded to the bottom of the second adhesive layer.

[0013] Preferably, the transfer head includes a pneumatic actuator and a gas nozzle arranged below the pneumatic actuator. The working pressure of the pneumatic actuator is 0.1-2 MPa, the working frequency is 50-500 Hz, and a plurality of air holes are arranged in the gas nozzle.

[0014] Preferably, the pneumatic nozzle sprays airflow in two pressure ranges, namely, low pressure and atmospheric pressure. The low pressure range is 0.1-1 MPa, and the atmospheric pressure range is 0.1-2 MPa.

[0015] Preferably, the microporous substrate is one or more of glass, sapphire, silicon and silicon carbide, the transmittance of the microporous substrate is greater than 88%, the diameter of the vertical through hole is 5-100 μm, and the diameter of the vertical through hole is much smaller than the diameter of the pore.

[0016] Preferably, the first adhesive layer and the second adhesive layer are one of organic silicone adhesive, epoxy resin adhesive and polyurethane adhesive, the adhesion of the first adhesive layer is 0.5N / 25mm-10N / 25mm, the adhesion of the second adhesive layer is 0.1N / 25mm-2N / 25mm, and the adhesion of the second adhesive layer to the chip to be transferred is less than the adhesion of solder paste or conductive glue to the chip to be transferred.

[0017] Preferably, the elastic layer is one or more materials selected from PDMS, TPE, TPEE, TPU, PU and TPR having recoverable deformation capability.

[0018] Preferably, the working distance between the microporous substrate and the gas nozzle is 0.1-0.5 mm, the chip to be transferred is located directly above the target substrate, and the working gap between the chip to be transferred and the target substrate is 400-800 μm.

[0019] A pneumatic mass transfer method based on a single-head multi-hole array, the steps are as follows:

[0020] S1. Start the pneumatic actuator, and the gas nozzle sprays a small air flow, which acts on the position on the microporous substrate corresponding to the chip to be transferred;

[0021] S2. A low-pressure airflow passes through the microporous substrate and acts on the first adhesive layer, the elastic layer, and the second adhesive layer in sequence. The first adhesive layer, the elastic layer, and the second adhesive layer undergo different degrees of plastic deformation in sequence, causing the first adhesive layer to leave the microporous substrate.

[0022] S3, the microporous substrate moves under the joint traction of the left vacuum suction cup and the right vacuum suction cup to achieve the alignment of the chip to be transferred and the solder joint.

[0023] S4, start the pneumatic actuator again and use atmospheric pressure to spray out atmospheric pressure air;

[0024] S5. Atmospheric pressure air flows through the microporous substrate and acts on the first adhesive layer, the elastic layer, and the second adhesive layer in sequence, causing the first adhesive layer, the elastic layer, and the second adhesive layer to generate bubbles of controllable size through huge plastic deformation;

[0025] S6. The chip to be transferred moves downward after the bubble swells and contacts the solder paste or conductive glue on the solder joint, so that the chip to be transferred adheres to the solder joint and the transfer is completed.

[0026] Therefore, the present invention adopts a pneumatic mass transfer device and method based on a single-head multi-porous array with the above-mentioned structure and steps, which uses a small air pressure to separate the viscous body from the microporous substrate in a small range, and uses atmospheric pressure to make the viscous body bulge bubbles, and transfers the chip to be transferred from under the second adhesive layer to the solder joint. The transfer efficiency is high, the yield rate is high, and the chip is not easily damaged.

[0027] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of a single-hole gas showerhead structure according to an embodiment of a pneumatic mass transfer device based on a single-head multi-hole array according to the present invention;

[0029] Figure 2 Schematic diagram of the viscous body state of a single-hole gas nozzle structure under low gas pressure according to an embodiment of the present invention;

[0030] Figure 3 Schematic diagram of the viscous body state of a single-hole gas nozzle structure under atmospheric pressure according to an embodiment of the present invention;

[0031] Figure 4 A schematic diagram of a gas nozzle with multiple air holes according to an embodiment of the present invention;

[0032] Figure 5 Schematic diagram of the viscous state of a multi-pore gas nozzle structure under low gas pressure according to an embodiment of the present invention;

[0033] Figure 6 Schematic diagram of the viscous state of a multi-hole gas nozzle structure under atmospheric pressure according to an embodiment of the present invention.

[0034] Reference numerals

[0035] 1. Transfer head; 11. Pneumatic actuator; 12. Air hole; 13. Gas nozzle; 2. Microporous substrate; 21. Vertical through hole; 3. Adhesive body; 31. First adhesive layer; 32. Elastic layer; 33. Second adhesive layer; 4. Chip to be transferred; 5. Left vacuum suction cup; 6. Right vacuum suction cup; 7. Target substrate; 71. Adhesive particles. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0037] Example

[0038] A pneumatic mass transfer device based on a single-head multi-hole array comprises a microporous substrate 2, a transfer head 1, a target substrate 7, and a viscous body 3.

[0039] The transfer head is arranged above the microporous substrate 2. The transfer head 1 includes a pneumatic actuator 11 and a gas nozzle 13 arranged below the pneumatic actuator 11. The pneumatic actuator 11 has a high-frequency start-stop gas blowing function. The working pressure of the pneumatic actuator 11 is 0.1-2MPa and the working frequency is 50-500Hz. A plurality of air holes 12 are arranged in the gas nozzle 13. The different number of air holes 12 makes the range of action of the gas nozzle 13 on the microporous substrate 2 different. Figure 1 The structure of the gas nozzle 13 with a single air hole 12 is shown in FIG. Figure 4 The middle part shows the structure of the gas nozzle 13 with multiple air holes 12. The gas nozzle 13 sprays airflow in two pressure ranges: low pressure and atmospheric pressure. The low pressure range is 0.1-1Mpa, and the atmospheric pressure range is 0.1-2Mpa.

[0040] The microporous substrate 2 is positioned above the target substrate 7 and secured to the left and right vacuum chucks 5 and 6 by vacuum suction. The left and right vacuum chucks 5 and 6 pull the microporous substrate 2 to move. The microporous substrate 2 is made of a rigid and light-transmitting material, such as one or more of glass, sapphire, silicon, and silicon carbide, with a light transmittance greater than 88%. A plurality of vertical through-holes 21 are uniformly distributed throughout the microporous substrate 2. The diameter of the vertical through-holes 21 ranges from 5 to 100 μm, which is much smaller than the diameter of the air holes 12.

[0041] The adhesive body 3 is bonded to the bottom surface of the microporous substrate 2. The adhesive body 3 includes a first adhesive layer 31, an elastic layer 32 and a second adhesive layer 33. The first adhesive layer 31 is bonded to the bottom of the microporous substrate 2, the elastic layer 32 is bonded to the bottom of the first adhesive layer 31, the second adhesive layer 33 is bonded to the bottom of the elastic layer 32, and the chip 4 to be transferred is bonded to the bottom of the second adhesive layer 33.

[0042] The first and second adhesive layers 31, 33 are made of silicone adhesive, epoxy resin adhesive, or polyurethane adhesive. The adhesion of the first adhesive layer 31 is between 0.5N / 25mm and 10N / 25mm, and the adhesion of the second adhesive layer 33 is between 0.1N / 25mm and 2N / 25mm. The elastic layer 32 is made of one or more of PDMS, TPE, TPEE, TPU, PU, ​​and TPR materials, which exhibit good deformability and strong tear and stretch resistance to ensure resilience after being subjected to stress.

[0043] The working distance between the microporous substrate 2 and the gas nozzle 13 is 0.1-0.5 mm. The chip to be transferred 4 is located directly above the target substrate 7, with a working gap of 400-800 μm between the chip to be transferred 4 and the target substrate 7. Several solder joints are provided above the target substrate 7, each with adhesive particles 71. The adhesive particles 71 are made of solder paste or conductive adhesive. The adhesion of the second adhesive layer 33 to the chip to be transferred 4 is weaker than that of the solder paste or conductive adhesive.

[0044] A pneumatic mass transfer method based on a single-head multi-hole array uses a coordinated approach of atmospheric pressure and low air pressure. The steps are as follows:

[0045] S1. Start the pneumatic actuator 11, and the gas nozzle 13 sprays a small pressure airflow, which acts on the position on the microporous substrate 2 corresponding to the chip 4 to be transferred;

[0046] S2, a small pressure air flow passes through the microporous substrate 2, and acts on the first adhesive layer 31, the elastic layer 32, and the second adhesive layer 33 in sequence. The first adhesive layer 31, the elastic layer 32, and the second adhesive layer 33 are plastically deformed to varying degrees, causing the first adhesive layer 31 to separate from the microporous substrate 2. For the gas nozzles 13 with a single air hole 12 and multiple air holes 12, in order to achieve the purpose of partially separating the first adhesive layer from the microporous substrate 2, the intervals at which the small pressure is applied are different, such as Figure 2 and Figure 5 shown.

[0047] S3, the microporous substrate 2 moves under the joint traction of the left vacuum suction cup 5 and the right vacuum suction cup 6 to achieve alignment between the chip 4 to be transferred and the solder joint;

[0048] S4, start the pneumatic actuator 11 again, and use atmospheric pressure to spray atmospheric pressure air;

[0049] S5, atmospheric pressure air flow passes through the microporous substrate 2, and acts on the first adhesive layer 31, the elastic layer 32, and the second adhesive layer 33 in sequence, causing the first adhesive layer 31, the elastic layer 32, and the second adhesive layer 33 to produce bubbles of controllable size through huge plastic deformation; the state of the bubbles formed by the single air hole 12 gas nozzle 13 is as follows Figure 3 As shown, the state of bubbles formed by the multi-hole 12 gas nozzle 13 is as follows Figure 6 shown.

[0050] S6. The chip 4 to be transferred moves downward after the bubble swells and contacts the solder paste or conductive glue on the solder joint, so that the chip 4 to be transferred adheres to the solder joint, completing the transfer.

[0051] Therefore, the present invention adopts a pneumatic mass transfer device and method based on a single-head multi-porous array with the above-mentioned structure and steps, which uses a small air pressure to separate the viscous body 3 from the microporous substrate 2 in a small range, and uses atmospheric pressure to make the viscous body 3 bulge with bubbles, and transfers the chip 4 to be transferred from under the second adhesive layer 33 to the solder joint. The transfer efficiency is high, the yield rate is high, and the chip is not easily damaged.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. 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 solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A pneumatic mass transfer device based on a single-head multi-hole array, characterized by: The transfer head includes a microporous substrate, a transfer head, a target substrate, and a viscous body; the viscous body includes a first adhesive layer, an elastic layer, and a second adhesive layer, the first adhesive layer is bonded to the bottom of the microporous substrate, the elastic layer is bonded to the bottom of the first adhesive layer, the second adhesive layer is bonded to the bottom of the elastic layer, and the chip to be transferred is bonded to the bottom of the second adhesive layer; the transfer head is arranged above the microporous substrate, the transfer head includes a pneumatic actuator and a gas nozzle arranged below the pneumatic actuator, the working pressure of the pneumatic actuator is 0.1-2MPa, and the working frequency is 50-500H z, a gas nozzle is provided with a plurality of air holes; the pneumatic nozzle ejects airflow in two pressure ranges, namely, micro-pressure and atmospheric pressure, with the micro-pressure range being 0.1-1 MPa and the atmospheric pressure range being 0.1-2 MPa; a microporous substrate is provided above a target substrate, with a plurality of vertical through holes evenly arranged on the microporous substrate; an adhesive body is bonded to the bottom surface of the microporous substrate, and a plurality of chips to be transferred are bonded below the adhesive body; a plurality of solder joints are provided above the target substrate, and adhesive particles are provided at the solder joints, and the adhesive particles are made of solder paste or conductive adhesive; A pneumatic mass transfer method based on a single-head multi-hole array, the steps are as follows: S1. Start the pneumatic actuator, and the gas nozzle sprays a small air flow, which acts on the position on the microporous substrate corresponding to the chip to be transferred; S2. A low-pressure airflow passes through the microporous substrate and acts on the first adhesive layer, the elastic layer, and the second adhesive layer in sequence. The first adhesive layer, the elastic layer, and the second adhesive layer undergo different degrees of plastic deformation in sequence, causing the first adhesive layer to leave the microporous substrate. S3, the microporous substrate moves under the joint traction of the left vacuum suction cup and the right vacuum suction cup to achieve the alignment of the chip to be transferred and the solder joint; S4, start the pneumatic actuator again and use atmospheric pressure to spray out atmospheric pressure air; S5. Atmospheric pressure air flows through the microporous substrate and acts on the first adhesive layer, the elastic layer, and the second adhesive layer in sequence, causing the first adhesive layer, the elastic layer, and the second adhesive layer to generate bubbles of controllable size through huge plastic deformation; S6. The chip to be transferred moves downward after the bubble swells and contacts the solder paste or conductive glue on the solder joint, so that the chip to be transferred adheres to the solder joint and the transfer is completed.

2. The pneumatic mass transfer device based on a single-head multi-hole array according to claim 1, characterized in that: The microporous substrate is fixed under the left vacuum suction cup and the right vacuum suction cup based on the vacuum adsorption force.

3. The pneumatic mass transfer device based on a single-head multi-hole array according to claim 1, characterized in that: The microporous substrate is made of one or more materials selected from glass, sapphire, silicon and silicon carbide. The light transmittance of the microporous substrate is greater than 88%, and the diameter of the vertical through hole is 5-100 μm, which is much smaller than the diameter of the pore.

4. The pneumatic mass transfer device based on a single-head multi-hole array according to claim 1, characterized in that: The first adhesive layer and the second adhesive layer are one of organic silicone adhesive, epoxy resin adhesive and polyurethane adhesive. The adhesion of the first adhesive layer is 0.5N / 25mm-10N / 25mm, and the adhesion of the second adhesive layer is 0.1N / 25mm-2N / 25mm. The adhesion of the second adhesive layer to the chip to be transferred is less than the adhesion of solder paste or conductive glue to the chip to be transferred.

5. The pneumatic mass transfer device based on a single-head multi-hole array according to claim 1, characterized in that: The elastic layer is one or more materials selected from PDMS, TPE, TPEE, TPU, PU and TPR having recoverable deformation capability.

6. The pneumatic mass transfer device based on a single-head multi-hole array according to claim 1, characterized in that: The working distance between the microporous substrate and the gas nozzle is 0.1-0.5 mm, the chip to be transferred is located directly above the target substrate, and the working gap between the chip to be transferred and the target substrate is 400-800 μm.

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