Mass transfer method

Abstract

The application provides a mass transfer method, comprising: covering an adhesive layer on a first surface of a receptor substrate, a plurality of original pads for electrical connection with a chip to be transferred being arranged on the first surface; removing the adhesive layer covering the original pads to expose the original pads; performing hydrophilic treatment on the exposed original pads to obtain treated pads with hydrophilicity; adding a target liquid on the treated pads to form a liquid film on the surface of the treated pads; performing hydrophilic treatment on a plurality of original chips on a donor substrate to obtain treated chips with hydrophilicity; moving the donor substrate to be in register above the receptor substrate, and irradiating laser on the side of the donor substrate away from the first surface to release the treated chips on the donor substrate from the donor substrate to the treated pads, and using the liquid film to pull back at least part of the treated chips falling thereon to a correct position and posture, so as to realize high-precision registration between the treated chips and the treated pads.

Description

Technical Field

[0001] This application relates to the field of display technology, and more specifically to a mass transfer method. Background Technology

[0002] Micro-LED (Micro Light-Emitting Diode) display technology is considered one of the next-generation mainstream display technologies due to its advantages such as high brightness, low power consumption, and long lifespan. However, its development is constrained by mass transfer technology, namely, how to efficiently and accurately transfer millions of micron-sized Micro-LED chips, typically 10µm to 100µm in size, from the donor substrate to the recipient substrate.

[0003] Laser mass transfer is one of the most promising technologies currently available. It involves using a laser beam to peel off the chip from the donor substrate, propelling the chip towards the recipient substrate, where it is captured by adhesive tape or pads. This technology demands extremely high chip placement accuracy, typically requiring sub-micron level (<0.5 µm) to ensure subsequent bonding yield and electrical connectivity of the display panel.

[0004] There are two main types of technologies used to solve the chip placement accuracy problem. The first type is high-precision vision-motion systems. These systems achieve one-time transfer to the correct position through a precision alignment platform and visual feedback. However, due to factors such as mechanical jitter, laser beam sway, and uncontrollable chip attitude during flight (e.g., flipping, drifting), the actual placement error is often between ±3µm, making it difficult to consistently meet sub-micron level requirements. Improving the accuracy of the vision and motion system would exponentially increase equipment costs and has physical limitations. The second type is post-placement auxiliary correction technologies, such as magnetic field guidance and electrostatic adsorption. Magnetic methods require additional magnetization of the Micro-LED chip, which may introduce magnetic contamination and alter the chip's photoelectric properties. Electrostatic methods are highly sensitive to the humidity and cleanliness of the environment, have complex control circuits, and are prone to chip breakdown.

[0005] Given that the aforementioned solutions struggle to balance accuracy and cost, a secondary correction using fluid-driven force after chip placement could potentially be an effective way to address the accuracy issue. However, the recipient substrate in these processes is typically covered with a temporary adhesive tape to capture chips that fly in during transfer; this tape is often made of hydrophobic material. Applying fluid correction directly to this hydrophobic tape surface makes it difficult for the liquid to spread and form stable droplets, rendering the fluid-driven force ineffective on the chip. Conversely, completely removing the tape for fluid correction would leave chips without a temporary anchor, significantly reducing yield. This contradiction makes fluid correction solutions difficult to apply directly in practical processes.

[0006] Therefore, there is an urgent need in this field for a low-cost, high-fault-tolerant secondary high-precision correction scheme that does not require complex preprocessing of the chip and is compatible with existing tape processes. Summary of the Invention

[0007] In view of the above problems, embodiments of this application provide a mass transfer method, comprising: covering an adhesive layer on a first surface of a recipient substrate, wherein a plurality of original pads are disposed on the first surface, the original pads being used for electrical connection with a chip to be transferred; removing the adhesive layer covering the original pads to expose the original pads; performing a hydrophilic treatment on the exposed original pads to obtain hydrophilic treated pads; adding a target liquid to the treated pads to form a liquid film on the surface of the treated pads; performing a hydrophilic treatment on a plurality of original chips on a donor substrate to obtain hydrophilic treated chips; moving and aligning the donor substrate above the recipient substrate; irradiating the side of the donor substrate away from the first surface with a laser to release the treated chips on the donor substrate from the donor substrate to the treated pads.

[0008] According to an embodiment of this application, hydrophilic treatment of the exposed original pads includes: covering the adhesive layer with a mask, wherein the mask has a cutout area corresponding to the original pads to expose the original pads; and subjecting the exposed original pads to oxygen-containing plasma treatment to obtain hydrophilic treated pads.

[0009] According to an embodiment of this application, hydrophilic treatment of multiple raw chips on a donor substrate includes: performing oxygen-containing plasma treatment on the surface of the raw chips or coating the surface of the raw chips with a hydrophilic polymer layer to obtain hydrophilic treated chips.

[0010] According to an embodiment of this application, the contact angle between the liquid film and the processed pad is less than or equal to 10°; the contact angle between the processed chip and the liquid film is less than or equal to 30°.

[0011] According to an embodiment of this application, the adhesive layer is hydrophobic, and the contact angle between the liquid film and the adhesive layer is greater than 90°.

[0012] According to an embodiment of this application, adding a target liquid to the processed pad to form a liquid film on the surface of the processed pad includes: adding the target liquid to the surface of the processed pad to form a liquid film by spraying, inkjet printing or steam condensation.

[0013] According to an embodiment of this application, removing the adhesive layer covering the original pads to expose the original pads includes: using a laser system to irradiate the adhesive layer with a laser along a preset scanning path to remove the adhesive layer covering each of the original pads, forming an opening that exposes the original pads.

[0014] According to embodiments of this application, the target liquid is selected from ethylene glycol, propylene glycol, or a mixture of ethylene glycol and deionized water, or a mixture of propylene glycol and deionized water.

[0015] According to an embodiment of this application, the adhesive layer is composed of a heat-release tape, which loses its adhesiveness after being heated to a preset temperature.

[0016] According to an embodiment of this application, moving the donor substrate above the recipient substrate includes: loading the donor substrate onto a motion platform and guiding the motion platform to move using a vision system to move the donor substrate above the recipient substrate.

[0017] The mass transfer method provided in this application has at least the following advantages compared with related technologies:

[0018] By hydrophilically treating the original pads to obtain hydrophilic post-pads, and then adding a target liquid to the post-pads to form a liquid film on their surface, the original chip is simultaneously hydrophilically treated to obtain a hydrophilic post-chip. Utilizing the surface tension gradient between the liquid film and the hydrophobic viscous layer on the post-chip, as well as the capillary action of the liquid film on the post-chip, at least a portion of the post-chip falling onto the liquid film is pulled back to the correct position and orientation. This achieves sub-micron or even nanometer-level automatic alignment between the post-chip and the post-pads, significantly outperforming mass transfer methods using high-precision vision-motion systems. It highly meets the bonding requirements between the chip and the pads, resulting in a significant improvement in the final bonding yield. A single fluid self-alignment process takes only a few seconds and can process all chips on the entire substrate in parallel, ensuring the high efficiency of the mass transfer process.

[0019] The tolerance for single-position deviation in mass laser transfer is relaxed from the submicron level to the micron level, directly reducing the cost and complexity of the laser alignment system, such as reducing requirements for platform jitter and optical distortion. This application retains the adhesive layer, thus preserving its temporary fixing function and flexible buffering function. The original chip only requires hydrophilic treatment, without magnetization, charging, or additional coating, avoiding damage or contamination to the photoelectric properties of the original chip. Attached Figure Description

[0020] The above-mentioned contents, other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0021] Figure 1 This schematic diagram illustrates the principle of hydrophilic treatment of the original pads according to an embodiment of this application.

[0022] Figure 2 This schematic diagram illustrates the principle of hydrophilic treatment of a raw chip according to an embodiment of this application.

[0023] Figure 3 This schematic diagram illustrates the principle of adding a target liquid to a processed pad according to an embodiment of this application;

[0024] Figure 4 The schematic diagram illustrates the principle of irradiating the side of the donor substrate away from the first surface with a laser according to an embodiment of the present application, so as to release the processed chip on the donor substrate from the donor substrate to the processed pad.

[0025] Figure 5 A three-dimensional structural diagram illustrating the formation of a liquid film on the surface of a processed pad according to an embodiment of this application is shown schematically.

[0026] Figure 6 The illustration shows a front view of a liquid film formed on the surface of a processed pad according to an embodiment of the present application;

[0027] Figure 7 This schematic diagram illustrates the structure of a processed chip falling onto a processed pad on a surface to form a liquid film, according to an embodiment of this application.

[0028] The above figures include the following reference numerals:

[0029] 100, Recipient substrate; 110, First surface; 121, Original pad; 122, Processed pad; 200, Donor substrate; 211, Original chip; 212, Processed chip; 300, Adhesive layer; 310, Window; 410, Target liquid; 420, Liquid film; 500, Mask; 510, Cutout area; 600, Laser; 700, Oxygen-containing plasma. Detailed Implementation

[0030] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0031] Figure 1 This schematic diagram illustrates the principle of hydrophilic treatment of the original pad 121 according to an embodiment of this application. Figure 2 This schematic diagram illustrates the principle of hydrophilic treatment of the original chip 211 according to an embodiment of this application. Figure 3 This schematic diagram illustrates the principle of adding target liquid 410 to the processed pad 122 according to an embodiment of this application. Figure 4 This schematic diagram illustrates the principle of irradiating the side of the donor substrate 200 opposite to the first surface 110 with a laser according to an embodiment of this application, so that the processed chip 212 on the donor substrate 200 is released from the donor substrate 200 to the processed pad 122. Figure 5 This schematic diagram illustrates a three-dimensional structure of a liquid film 420 formed on the surface of the processed pad 122 according to an embodiment of this application. Figure 6 This schematically illustrates a front view of a liquid film 420 formed on the surface of the processed pad 122 according to an embodiment of this application. Figure 7 The schematic diagram illustrates the structure of the processed chip 212 falling onto the processed pad 122 on the surface where a liquid film 420 is formed, according to an embodiment of the present application.

[0032] The specific embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0033] Please see Figures 1-7The mass transfer method provided in this application includes: covering a first surface 110 of a recipient substrate 100 with an adhesive layer 300, wherein a plurality of original pads 121 are disposed on the first surface 110, and the original pads 121 are used for electrical connection with the chip to be transferred; removing the adhesive layer 300 covering the original pads 121 to expose the original pads 121; performing a hydrophilic treatment on the exposed original pads 121 to obtain hydrophilic treated pads 122; adding a target liquid 410 to the treated pads 122 to form a liquid film 420 on the surface of the treated pads 122; and performing a hydrophilic treatment on a plurality of original chips 211 on a donor substrate 200 to obtain hydrophilic treated chips 212. The donor substrate 200 is moved and aligned above the recipient substrate 100, and a laser 600 is irradiated on the side of the donor substrate 200 opposite to the first surface 110, so that the processed chip 212 on the donor substrate 200 is released from the donor substrate 200 to the processed pad 122.

[0034] In some embodiments, the recipient substrate 100 may be a 0.5 mm thick glass substrate. An array of original pads 121 is fabricated on one side of the glass substrate using photolithography and electroplating processes. The original pads 121 may be cylindrical with a diameter of 25 µm and a thickness of 0.6 µm. The array spacing of the original pads 121 may be set to 100 µm. The original pads 121 may be made of gold. The original chip 211 may be a square chip with dimensions of 30 µm × 30 µm. In some embodiments, the target liquid 410 may be deionized pure water.

[0035] After the donor substrate 200 is irradiated with a laser on the side away from the first surface 110, the processed chip 212 on the donor substrate 200 falls near the processed pad 122. That is, most of the processed chip 212 falls within the area of ​​the liquid film 420 of the processed pad 122 and has no contact with the adhesive layer 300. Even if this part of the processed chip 212 is slightly tilted (the electrode pins at the bottom of the processed chip 212 are not directly facing the processed pad 122), it can be pulled back to the correct posture with the electrode pins facing the processed pad 122 under the action of the surface tension of the liquid film 420. A small portion of the processed chip 212 will partially land on the adhesive layer 300 and partially on the liquid film 420. Because the adhesive layer 300 is hydrophobic and the processed chip 212 is hydrophilic, the processed chip 212 will automatically detach from the adhesive layer 300 under the influence of surface tension gradient and capillary force, and be pulled towards the center of the liquid film 420, eventually stabilizing in the center of the processed pad 122. This process is completed within seconds, with alignment accuracy reaching sub-micron levels. The remaining very small portion of the processed chip 212 with a larger offset distance will land entirely on the adhesive layer 300 without contacting the liquid film 420. These can be individually patched or marked as defects.

[0036] The mass transfer method provided in this application embodiment obtains a hydrophilic treated pad 122 by hydrophilic treatment of the original pad 121, and adds a target liquid 410 to the treated pad 122 to form a liquid film 420 on its surface. At the same time, the original chip 211 is hydrophilic treated to obtain a hydrophilic treated chip 212. Utilizing the surface tension gradient between the liquid film 420 and the hydrophobic adhesive layer 300 on the treated chip 212, as well as the capillary action of the liquid film 420 on the treated chip 212, the treated chip 212, which falls at least partially on the liquid film 420, is pulled back to the correct position and orientation. This achieves submicron or even nanometer-level automatic alignment between the treated chip 212 and the treated pad 122, which is significantly better than the alignment accuracy of mass transfer methods using high-precision vision-motion systems (typically 1µm to 2µm). It highly meets the bonding requirements between the chip and the pad, and significantly improves the final bonding yield between the chip and the pad. Furthermore, alignment of a single processed chip 212 with the pad can be achieved in just a few seconds, and the alignment process of all processed chips 212 can occur in parallel, thereby ensuring the high efficiency of the mass transfer process.

[0037] The tolerance for single-position deviation in mass laser transfer is relaxed from the submicron level to the micron level, which directly reduces the cost and complexity of the laser alignment system, such as reducing the requirements for platform jitter and optical distortion. This application retains the adhesive layer 300, thus preserving its temporary fixing function and flexible buffering function. The original chip 211 only needs to undergo hydrophilic treatment, without magnetization, charging, or additional coating, avoiding damage or contamination to the optoelectronic properties of the original chip 211.

[0038] Please see Figure 1 In some embodiments, hydrophilic treatment of the exposed original pads 121 includes covering the adhesive layer 300 with a mask 500. It is understood that the adhesive layer 300 is a portion of the adhesive layer 300 that has been removed from the original pads 121 and is now covering areas of the first surface 110 outside the original pads 121. The mask 500 protects the adhesive layer 300, reducing the impact of the plasma treatment process on its hydrophobicity and adhesiveness. The mask 500 has a cutout area 510 corresponding to the original pads 121 to expose them. The exposed original pads 121 are then treated with oxygen-containing plasma 700. In some embodiments, oxygen, water vapor, or a mixture thereof can be used for plasma treatment to obtain hydrophilic treated pads 122.

[0039] In the plasma state, oxygen-containing gas generates highly active oxygen-containing free radicals, which can react with the original pad 121 surface to introduce oxygen-containing polar groups (such as hydroxyl and carboxyl groups), thereby significantly improving the hydrophilicity of the original pad 121.

[0040] Please see Figure 2 In some embodiments, hydrophilic treatment of multiple raw chips 211 on the donor substrate 200 includes: oxygen-containing plasma treatment of the surface of the raw chip 211. In some embodiments, the donor substrate 200 can be placed in a plasma cleaner, oxygen is introduced, and the treatment is performed at 50 W power for 40 seconds. The contact angle between the bottom of the treated chip 212 and the liquid film 420 is measured to meet the hydrophilicity requirements. Alternatively, a hydrophilic polymer layer can be coated on the surface of the raw chip 211. The hydrophilic polymer can be selected from, but is not limited to, polyvinyl alcohol, polyethylene glycol, polyacrylic acid, polyamide, or polymers containing polar groups such as hydroxyl, carboxyl, and amide groups. The coating method includes spin coating, spray coating, dip coating, or inkjet printing to obtain a hydrophilic treated chip 212. Both of the above hydrophilic treatment methods can make the treated chip 212 have high hydrophilicity, thereby effectively ensuring the adsorption between the treated chip 212 and the liquid film 420.

[0041] Please see Figure 6 In some embodiments, the contact angle (θ1) between the liquid film 420 and the processed pad 122 is less than or equal to 10°, so that the liquid film 420 forms a low crescent-shaped structure with a slightly upward convex center on the surface of the processed pad 122, thereby minimizing the vertical distance between the processed chip 212 and the processed pad 122, and ensuring that the processed chip 212 is securely attached to the liquid film 420. A contact angle between the processed chip 212 and the liquid film 420 of less than or equal to 30° is sufficient to ensure reliable attachment of the processed chip 212 to the liquid film 420. In some embodiments, the contact angle between the liquid film 420 and the processed pad 122 can be set to be smaller than the contact angle between the processed chip 212 and the liquid film 420, such as the former being set to 6°, 8°, or 10°, and the latter being set to 20°, 25°, or 28°.

[0042] In some embodiments, the adhesive layer 300 is hydrophobic, and the contact angle between the liquid film 420 and the adhesive layer 300 is greater than 90°, so as to ensure the surface tension gradient between the liquid film 420 and the adhesive layer 300 on the treated chip 212, thereby making the treated chip 212 25 µm thick and the tape with the brand name REVALPHA 3195V manufactured by Nitto Denko Corporation with a contact angle of 95° with pure water.

[0043] Please see Figure 3In some embodiments, adding the target liquid 410 to the processed pad 122 to form a liquid film 420 on the surface of the processed pad 122 includes adding the target liquid 410 to the surface of the processed pad 122 by spraying, inkjet printing, or steam condensation to form the liquid film 420. It is understood that if, before adding the target liquid 410, there is a mask 500 on the recipient substrate 100 for hydrophilic treatment of the original pad 121, in order to prevent damage to the structure of the liquid film 420 due to subsequent removal of the mask 500, and to prevent the mask 500 itself from affecting the morphology of the liquid film 420, the mask 500 should be removed from the adhesive layer 300 before adding the target liquid 410 to the surface of the processed pad 122.

[0044] In some embodiments, in a cleanroom environment, a spraying device with arrayed nozzles can be used to uniformly spray the target liquid 410 in the form of mist droplets onto the first surface 110 of the receiver substrate 100. The spraying amount is controlled according to the area of ​​the receiver substrate 100 and the distribution density of the original pads 121 to ensure that each area of ​​the original pads 121 is covered by liquid. After spraying, the receiver substrate 100 is left to stand to allow the liquid film 420 to spread out naturally and evenly. The spraying method is simple to operate, the equipment is mature, and it is suitable for rapid liquid coverage of large-area receiver substrates 100.

[0045] In some embodiments, the target liquid 410 can be precisely sprayed onto the surface of the original pad 121 using an inkjet head capable of controlling the droplet volume to the picoliter to nanoliter level.

[0046] In other embodiments, the receptor substrate 100 may be placed in a sealed processing chamber, and the target liquid 410 (such as deionized water) may be heated to evaporate it, so that the vapor condenses on the first surface 110 of the receptor substrate 100 at a relatively low temperature to form a uniform liquid film.

[0047] In some embodiments, removing the adhesive layer 300 covering the original pads 121 to expose the original pads 121 includes: using a laser system, such as an excimer laser system, to irradiate the adhesive layer 300 along a preset scanning path (the coordinate parameters of each original pad 121 can be recorded in the preset scanning path), thereby removing the adhesive layer 300 covering each original pad 121 and forming an opening 310 exposing the original pads 121. Compared to methods such as mechanical scraping, using a laser system can precisely and efficiently remove the adhesive layer 300 covering each original pad 121.

[0048] In some embodiments, the target liquid may be ethylene glycol, propylene glycol, or a mixture of ethylene glycol and deionized water, or a mixture of propylene glycol and deionized water. Compared to pure water, the above liquids have lower surface tension and spread more easily on the surface of the processed pad 122, thereby forming a more stable liquid film 420 with a smaller contact angle to the surface of the processed pad 122 and the surface of the processed chip 212. Furthermore, the above liquids have higher boiling points and lower volatility, which can significantly extend the time that the liquid film 420 remains stable on the processed pad 122, thus allowing more operating time for the subsequent self-alignment process of the processed chip 212. In addition, the above polar liquids are non-corrosive to the pads, thereby ensuring the safety of the process.

[0049] In some embodiments, ethylene glycol and deionized water can be mixed at a volume ratio of 7:3 to obtain a mixture, and the mixture can be ultrasonically degassed for 10 minutes to obtain the target liquid 410. Using a piezoelectric inkjet head, the droplet volume is set to 10 pL, the spraying density is about 0.3 µL / cm², and the receiver substrate 100 is scanned and sprayed according to a preset path.

[0050] In some embodiments, the adhesive layer 300 is composed of a heat-release tape that loses its adhesiveness after being heated to a preset temperature. In some embodiments, the heat-release tape may be REVALPHA 3195V tape manufactured by Nitto Denko Corporation, with a preset temperature of 110°C.

[0051] After the processed chip 212 completes the self-alignment process with the processed pad 122, the recipient substrate 100 can be placed on a heating device and heated for a period of time to allow the liquid film 420 to evaporate. Then, it is heated to a preset temperature and held for a period of time to allow the heat release tape to lose its stickiness. Then, the heat release tape is easily peeled off from the first surface 110 using tools such as tweezers. Finally, under the protection of gases such as nitrogen, the recipient substrate 100 is sent into a reflow oven to complete the bonding of the processed chip 212 and the processed pad 122.

[0052] In some embodiments, moving the donor substrate 200 above the recipient substrate 100 includes: loading the donor substrate 200 onto a motion platform, and guiding the motion platform to move via a vision system to move the donor substrate 200 above the recipient substrate 100. This ensures that the positional deviation between the processed chip 212 released from the donor substrate 200 onto the recipient substrate 100 and the processed pad 122 is within a small range, thereby allowing more of the processed chip 212 to contact the liquid film 420, or increasing the contact area between the processed chip 212 and the liquid film 420, thus improving the overall alignment accuracy of the processed chip 212 and the processed pad 122. In some embodiments, using the above-described alignment scheme of motion platform and vision system, the placement accuracy of the processed chip 212 and the processed pad 122 can be controlled within 2µm, while the size of the processed chip 212 is typically greater than 10µm to 100µm, thus ensuring that the processed chip 212 is at least partially in contact with the liquid film 420.

[0053] Those skilled in the art will understand that the features described in the various embodiments of this application can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application.

Claims

1. A mass transfer method, characterized in that, include: An adhesive layer is applied to a first surface of a recipient substrate, the first surface having a plurality of original pads for electrical connection to the chip to be transferred. Remove the adhesive layer covering the original pads to expose the original pads; The exposed original pads are subjected to a hydrophilic treatment to obtain hydrophilic treated pads; A target liquid is added to the treated pads to form a liquid film on the surface of the treated pads. Multiple original chips on the donor substrate were subjected to hydrophilic treatment to obtain hydrophilic treated chips; The donor substrate is moved and aligned above the recipient substrate, and a laser is irradiated on the side of the donor substrate facing away from the first surface, so that the processed chip on the donor substrate is released from the donor substrate to the processed pad.

2. The mass transfer method according to claim 1, characterized in that, The hydrophilic treatment of the exposed original pads includes: A mask is placed over the adhesive layer, and the mask has a cutout area corresponding to the original pads to expose the original pads; The exposed original pads are subjected to oxygen-containing plasma treatment to obtain hydrophilic treated pads.

3. The mass transfer method according to claim 1, characterized in that, Hydrophilic treatment of multiple raw chips on the donor substrate includes: The original chip surface is subjected to oxygen-containing plasma treatment or coated with a hydrophilic polymer layer to obtain a hydrophilic treated chip.

4. The mass transfer method according to claim 1, characterized in that, The contact angle between the liquid film and the treated pad is less than or equal to 10°; the contact angle between the treated chip and the liquid film is less than or equal to 30°.

5. The mass transfer method according to claim 1, characterized in that, The adhesive layer is hydrophobic, and the contact angle between the liquid film and the adhesive layer is greater than 90°.

6. The mass transfer method according to claim 1, characterized in that, Adding the target liquid to the treated pads to form a liquid film on the surface of the treated pads includes: The target liquid is added to the surface of the treated pads to form a liquid film by means of spraying, inkjeting, or steam condensation.

7. The mass transfer method according to claim 1, characterized in that, Removing the adhesive layer covering the original pads to expose the original pads includes: Using a laser system, the adhesive layer is irradiated with laser according to a preset scanning path to remove the adhesive layer covering each of the original pads, forming an opening that exposes the original pads.

8. The mass transfer method according to claim 1, characterized in that, The target liquid is selected from ethylene glycol, propylene glycol, or a mixture of ethylene glycol and deionized water, or a mixture of propylene glycol and deionized water.

9. The mass transfer method according to claim 1, characterized in that, The adhesive layer is made of heat-release tape, which loses its adhesiveness after being heated to a preset temperature.

10. The mass transfer method according to claim 1, characterized in that, Moving and aligning the donor substrate above the recipient substrate includes: The donor substrate is mounted on a motion platform, and the motion platform is guided by a vision system to move and align the donor substrate above the recipient substrate.

Images