Packaging process of LED display screen and LED display screen

Abstract

The application relates to a packaging process of an LED display screen and the LED display screen. The process comprises the following steps: S1, cleaning a release film and an LED unit plate; S2, performing dam treatment on the release film laid on a carrier film jig to form a dam glue, wherein the inner side of the dam glue forms a unit bonding area for bonding the LED unit plate; S3, performing glue filling treatment in the unit bonding area of the release film to form packaging glue, wherein the glue is UV double-curing glue; S4, assembling the carrier plate jig loaded with the LED unit plate and the carrier film jig laid with the release film; S5, performing vacuum bubble removal treatment on the packaging glue; S6, performing pressing treatment on the carrier plate jig in a vacuum environment; S7, performing UV curing treatment on the packaging glue; S8, removing the carrier plate jig and the carrier film jig; and S9, performing heat curing treatment on the packaging glue. The application has the effect of manufacturing an LED display screen with higher optical performance through a more efficient process flow.

Description

Technical Field

[0001] This application relates to the field of LED processing technology, and in particular to a packaging process for an LED display screen and an LED display screen. Background Technology

[0002] GOB (Glue On Board) is a surface treatment technology that encapsulates LED unit boards onto a release film or substrate using adhesive. Its core purpose is to obtain a highly flat encapsulated adhesive surface with a frosted optical appearance. Currently, the mainstream GOB process in the industry uses a thermosetting adhesive system. The typical process is as follows: damming and pouring adhesive onto the release film, bonding the LED unit board to the adhesive layer through vacuum pressing, then removing the fixture holding the release film and LED unit board, allowing the adhesive to dry for a period of time, and finally sending it into a hot oven for complete curing.

[0003] However, the GOB process using thermosetting adhesives described above has the following technical problems: First, the adhesive drying process is time-consuming, reducing production line efficiency. Simultaneously, the adhesive surface is exposed to ambient air for an extended period during drying, making it susceptible to the accumulation of dust, fibers, and other foreign matter. This can lead to surface defects such as particles and white spots after encapsulation, impacting yield.

[0004] Secondly, the curing process relies on the adhesive's natural leveling to improve smoothness. However, the leveling effect is affected by various factors such as ambient temperature and humidity, adhesive viscosity, and application thickness, resulting in a narrow processing window and making it difficult to consistently achieve the ultimate smoothness of the adhesive surface. In addition, the internal stress generated by the volume shrinkage of the adhesive during thermosetting lacks an effective release pathway, which can easily cause micro-wrinkles on the adhesive surface, wrinkling of the release film, or warping of the LED board, further impairing optical uniformity. Summary of the Invention

[0005] In order to manufacture LED displays with higher optical performance through a more efficient process, this application provides an LED display packaging process and an LED display.

[0006] In a first aspect, this application provides a packaging process for an LED display screen, employing the following technical solution: An LED display packaging process includes the following steps: S1. Clean the release film and LED unit board; S2. The release film laid on the carrier film fixture is dammed to form a damming adhesive, wherein the inner side of the damming adhesive forms a unit bonding area for LED unit boards to be bonded. S3. A potting process is performed in the unit bonding area of ​​the release film to form an encapsulating adhesive, wherein the adhesive is a UV dual-curing adhesive. S4. Assemble the carrier board fixture containing the LED unit board and the carrier film fixture with the release film, so that the LED unit board and the encapsulating adhesive are arranged in a spaced-out relative manner. S5. Vacuum degassing treatment is performed on the encapsulating adhesive; S6. Press the carrier board fixture in a vacuum environment to connect the LED unit board with the encapsulating adhesive. S7. While maintaining a predetermined clamping force between the carrier plate fixture and the carrier film fixture, perform UV curing treatment on the encapsulating adhesive. S8. Remove the carrier plate fixture and film carrier fixture; S9. Perform thermosetting treatment on the encapsulating adhesive.

[0007] By adopting the above technical solution, based on the premise that the adhesive is a UV dual-curing adhesive: First, after lamination, UV curing can be used to gel and set the encapsulating adhesive, which can then be directly heat-cured. This process eliminates the drying step, making the process faster and avoiding the adverse effects of dust and ambient temperature and humidity during the drying stage. Second, UV pre-curing can maintain the smooth surface of the encapsulating adhesive after lamination. When heat-curing is performed, the encapsulating adhesive has already gelled, resulting in less shrinkage stress. Unlike full UV curing, it will not produce defects such as ripples or orange peel due to instantaneous volume shrinkage. The final smoothness of the encapsulating adhesive can even exceed the limits achievable by pure heat curing. Third, because UV curing + heat curing mainly relies on heat curing, UV dual-curing adhesives can be supplemented with frosting powder, diffusion particles, and colorants as needed. These will not block UV light, allowing for precise control of the encapsulating adhesive's haze, gloss, and diffuse reflection properties.

[0008] Preferably, the release film fixture is a carrier used on a linear conveyor line, and in S1, if the release film is a roll, the release film laying process between S1 and S2 is achieved by the coordinated operation of a roll-pressing device and a vacuum adsorption device. Specifically, the release film laying adopts the following steps: S101. The position lock of the carrier film fixture is performed by vacuum adsorption. S102. With an air suspension layer above the carrier film fixture, the release film is transferred to a predetermined position above the carrier film fixture. S103. Roll the release film from the direction away from the release film roll to the direction close to the release film roll. During the rolling process, the area on the carrier film fixture where the release film is attached is vacuum-adsorbed, while the area on the carrier film fixture where the release film is not attached is under normal pressure. S104. Vacuum adsorption is used to make the release film adhere tightly to the edge of the carrier film fixture; S105. Cut the release film; S106. Allow the release film on the carrier film fixture to stand for a period of time.

[0009] By adopting the above technical solution, firstly, the release film is a roll material, which can be adapted to large-scale, high-volume production lines. Moreover, during the laying process, the release film is laid from one side of the carrier film fixture to the opposite side, which can achieve air venting and make the film flatly laid on the carrier film fixture.

[0010] Secondly, since the packaging process of LED displays requires multiple steps, using a linear conveyor line to transfer the carrier film fixture results in a faster process cycle.

[0011] Third, given that the carrier film fixture moves on the linear conveyor line, a vacuum adsorption device is used to precisely control the relative position between the carrier film fixture and the release film, as well as the state of the release film during the laying process. Specifically, in S101, the vacuum adsorption device locks the carrier film fixture in a predetermined position using negative pressure. In S102, gas is delivered through other air channels in the vacuum adsorption device to form an air suspension layer. At this time, the release film will be suspended on the surface of the carrier film fixture, facilitating fine-tuning of the release film's position. Therefore, when fine-tuning the release film, the release film will not be adsorbed onto the carrier film fixture, preventing wrinkles or deformation. In S103, during the rolling process, the vacuum adsorption equipment uses negative pressure to adsorb only the area of ​​the release film already applied in the carrier film fixture. This maintains the position of the carrier film fixture and, since the release film has just passed over this area, there is electrostatic attraction between the release film and the glass, which may cause rebound stress attempting to wrinkle the film. At this time, the negative pressure can be used to fix the already laid release film, counteracting the tensile stress of the release film and preventing the formation of tiny wrinkles and slight displacements. In S104, the portion of the release film near the edge of the carrier film fixture is adsorbed by vacuum and then cut to prevent deformation of the release film after cutting.

[0012] Fourth, in S106, after static treatment, the release film is allowed to relax and rebound to eliminate internal stress, thereby avoiding problems such as cracking of the dammed adhesive, uneven thickness of the potting adhesive, and delamination of the encapsulating adhesive after curing.

[0013] In summary, the goal is to achieve high-quality packaging technology while meeting the requirements of large-scale, high-volume, and fast-paced production.

[0014] Preferably, in S2, the cross-section of the dammed adhesive is a trapezoid or semi-circle that is narrower at the top and wider at the bottom.

[0015] By adopting the above technical solution, the top-narrow, bottom-wide structure has the following advantages: First, during the potting process, the encapsulating adhesive generates an outward hydrostatic pressure on the inner wall of the damming adhesive. The pressure increases with the depth of the adhesive, reaching its maximum at the bottom of the dam. The top-narrow, bottom-wide structure provides stronger support for the damming adhesive, preventing deformation or cracking. Second, during the pressing process, the inclined surface on the inner side of the damming adhesive guides the adhesive upwards, allowing it to fill the tiny gaps at the bottom and sides of the LED unit board. Third, the top-narrow, bottom-wide structure provides sufficient support to resist the pressure transmitted from the LED unit board through the encapsulating adhesive, making the damming adhesive less prone to deformation and helping to maintain the consistency of the encapsulating adhesive thickness. Fourth, during the pressing process, the larger space on the upper side of the damming adhesive provides space for air bubbles to escape, thereby reducing the complexity of subsequent leveling treatment of the encapsulating adhesive.

[0016] Regarding the cross-sectional shape of the damming adhesive, the trapezoidal shape is the easiest to apply and form, while the semi-circular shape can further improve the impact resistance of the damming adhesive to meet the application scenarios with higher encapsulation process requirements.

[0017] Preferably, in step S2, if the damming adhesive is a hot melt adhesive, the viscosity of the damming adhesive is 3500-8000 mPa·s at 160°C, and the thixotropic index is between 3 and 5; if the damming adhesive is a thermosetting adhesive, the viscosity of the damming adhesive is 20000-50000 mPa·s at 25°C, and the thixotropic index is between 3 and 5; if the damming adhesive is a UV adhesive, the viscosity of the damming adhesive is 8000-15000 mPa·s at 25°C, and the thixotropic index is between 3 and 5.

[0018] By adopting the above technical solutions, firstly, because if the damming adhesive is too thin, it will flow and destroy the ring structure, while if it is too thick, it will be difficult to form a narrow dam body. Therefore, a medium viscosity and high thixotropic adhesive is selected, which thins during extrusion and thickens rapidly after settling. Secondly, hot melt adhesive is selected, which can naturally cool and cure after extrusion, resulting in high production efficiency and low production cost, making it suitable for mass automated production; thermosetting adhesive is selected, which has high reliability and is suitable for harsh working conditions; and UV adhesive is selected, which offers flexible process windows and is suitable for high-precision continuous production.

[0019] Preferably, in S2, if the dispensing valve is a piezoelectric jet valve, during dispensing, the ejector pin is moved first without hitting the nozzle seat, so that a pre-filled glue droplet is formed on the outside of the nozzle, and then the ejector pin hits the nozzle seat at high speed, so that a complete main glue droplet is formed on the outside of the nozzle; if the dispensing valve is a back suction valve, after dispensing is completed, the outside of the nozzle is cleaned.

[0020] By adopting the above technical solution, during the damming process, the ring-shaped area formed by the damming adhesive must be completely closed, while avoiding splashing the damming adhesive into the predetermined area inside the ring.

[0021] If a piezoelectric spray valve is selected, firstly, a closed annular adhesive strip can be formed by high-frequency spraying of continuous adhesive dots. Secondly, by using near-field spraying, combined with a method of first gently pushing the ejector pin and then moving it at high speed, the adhesive droplets are prevented from breaking into satellite points at the tail end, thus preventing the dammed adhesive from splashing into the inner area of ​​the ring.

[0022] If a backflow valve is selected, firstly, the annular area can be completely closed using an overlapping initiation method. Secondly, since the adhesive is extruded, cleaning the nozzle promptly after each application can prevent adhesive from splashing into the annular area.

[0023] Preferably, the adhesive is degassed before step S3; and the encapsulating adhesive is vacuum-treated after step S3 and before step S4.

[0024] By adopting the above technical solution, the encapsulating adhesive needs better leveling before lamination, resulting in better surface flatness of the LED display and a frosted optical surface that more closely resembles the release film. First, the adhesive undergoes degassing before potting to remove most of the tiny air bubbles, thus promoting leveling speed and preventing the formation of large, visible air bubbles during subsequent leveling. Second, vacuuming is used to promote adhesive leveling and remove air bubbles before assembling the carrier film fixture and carrier board fixture. By combining these two methods, the vacuum degassing process before lamination only needs to remove interface air bubbles, and the process time is very short. In summary, the pretreatment of the adhesive and the step-by-step vacuum treatment further improve the process cycle time and enhance the product quality of the LED display.

[0025] Preferably, before step S4, the LED unit board is subjected to plasma treatment, wherein the gas used for plasma treatment is a mixture of argon and oxygen, and the volume ratio of argon to oxygen is 8:1-10:1.

[0026] By adopting the above technical solutions, firstly, plasma treatment can treat extremely small contaminants to achieve high microscopic cleanliness, and it can also increase surface tension, promoting subsequent coating and bonding processes, resulting in better coating adhesion and stronger bonding. Secondly, a mixture of argon and oxygen is used, where argon primarily performs physical roughening, increasing surface microscopic roughness through physical bombardment, providing more bonding area for the adhesive, while oxygen primarily performs chemical activation, using chemical oxidation to introduce polar groups such as hydroxyl groups, increasing surface energy, and enabling the adhesive to better wet and spread.

[0027] Preferably, in step S6, an airbag is used for the pressing process, and the pressure change during the pressing process is as follows: first low pressure, then high pressure, then pressure holding, and finally step-by-step pressure release.

[0028] By adopting the above technical solution, firstly, the process involves low pressure followed by increased pressure, then pressure holding, and finally step-by-step pressure release. The advantages of this pressing method are that the initial low pressure allows the adhesive to spread slowly, giving the interface air bubbles enough time to escape and preventing the instantaneous high pressure from locking the air bubbles inside the adhesive layer; the mid-stage pressure increase provides sufficient power to press the adhesive into the bottom of the LED beads and the dense gaps, achieving void-free filling; the pressure holding allows the adhesive to complete its flow and initial shaping under pressure; and the step-by-step pressure release prevents the adhesive from rebounding due to sudden pressure changes, avoiding the generation of new microbubbles or separation of the adhesive layer from the LED unit board interface.

[0029] Secondly, using airbags for pressing is more suitable for the pressing process of first low pressure, then high pressure, then pressure holding, and finally step-by-step pressure release. It can also adapt to LED unit boards of different thicknesses by changing the pressure inside the airbag.

[0030] Preferably, after S7 and before S8, a cooling process is performed until the gel strength and coefficient of thermal expansion of the encapsulating adhesive reach a predetermined value. Then, the self-pressurization between the carrier plate fixture and the carrier film fixture is released, and then the carrier plate fixture covers the LED unit board for a predetermined time until the final thermal equilibrium and stress release are achieved.

[0031] By adopting the above technical solution, firstly, if the fixture is disassembled at high temperature, the gel strength of the encapsulating adhesive is insufficient and its coefficient of thermal expansion is still high. Therefore, the gel strength of the encapsulating adhesive is insufficient to resist mechanical disturbances when the fixture is removed. Simultaneously, due to the sudden release of constraints, the different rebound amounts among the adhesive layer, LED unit board, and fixture can easily lead to wrinkling of the adhesive surface or warping of the board. Secondly, after releasing the self-pressurization between the carrier board fixture and the carrier film fixture, the carrier board fixture applies slight constraints to the LED unit board to achieve final thermal balance and stress, thereby further preventing warping.

[0032] Secondly, this application provides an LED display screen, which adopts the following technical solution: An LED display screen is manufactured using the aforementioned LED display screen packaging process.

[0033] By adopting the above technical solutions, it is possible to manufacture LED displays with higher optical performance using a more efficient process.

[0034] In summary, this application includes at least one of the following beneficial technical effects: 1. Based on the premise that the adhesive is a UV dual-curing adhesive. First, after lamination, UV curing allows the encapsulating adhesive to gel and set, followed by direct heat curing. This process eliminates the need for drying, resulting in a faster workflow and avoiding the adverse effects of dust accumulation and ambient temperature and humidity during the drying stage. Second, UV pre-curing maintains a smooth surface for the encapsulating adhesive after lamination. During subsequent heat curing, the encapsulating adhesive has already gelled, resulting in lower internal shrinkage stress. Unlike full UV curing, it avoids defects such as ripples or orange peel caused by instantaneous volume shrinkage. The final smoothness of the encapsulating adhesive can even exceed the limits achievable with pure heat curing. Third, because UV curing + heat curing primarily relies on heat curing, UV dual-curing adhesives can be supplemented with frosting powder, diffusion particles, and colorants as needed. These do not block UV light, allowing for precise control of the encapsulating adhesive's haze, gloss, and diffuse reflection properties. Attached Figure Description

[0035] Figure 1 This is a flowchart illustrating the LED display packaging process in the embodiments of this application.

[0036] Figure 2 This is a schematic diagram illustrating the cooperation between the carrier film fixture and the vacuum adsorption platform during the roll-pressing process in this application embodiment. Detailed Implementation

[0037] The following is in conjunction with the appendix Figure 1-2 This application will be described in further detail.

[0038] This application discloses a packaging process for an LED display screen. (Refer to...) Figure 1 The packaging process includes the following steps: S1. Clean the release film and LED unit board; S2. The release film laid on the carrier film fixture is dammed to form a damming adhesive, wherein the inner side of the damming adhesive forms a unit bonding area for LED unit boards to be bonded. S3. A potting process is performed in the unit bonding area of ​​the release film to form an encapsulating adhesive, wherein the adhesive is a UV dual-curing adhesive. S4. Assemble the carrier board fixture containing the LED unit board and the carrier film fixture with the release film, so that the LED unit board and the encapsulating adhesive are arranged in a spaced-out relative manner. S5. Vacuum degassing treatment is performed on the encapsulating adhesive; S6. Press the carrier board fixture in a vacuum environment to connect the LED unit board with the encapsulating adhesive. S7. While maintaining a predetermined clamping force between the carrier plate fixture and the carrier film fixture, perform UV curing treatment on the encapsulating adhesive. S8. Remove the carrier plate fixture and film carrier fixture; S9. Perform thermosetting treatment on the encapsulating adhesive.

[0039] Based on the above steps, it can be seen that this application uses a UV dual-curing adhesive, which is an adhesive that requires both UV curing and heat curing to achieve complete curing. It is also known as a UV-heated dual-curing adhesive or a UV-thermal curing adhesive. Based on this, the process of first UV curing and then heat curing has the following advantages: First, after lamination, UV curing can be used to set the encapsulating adhesive gel, which can then be directly heat-cured. This process eliminates the need for drying the adhesive, making the process faster and avoiding the adverse effects of dust and ambient temperature and humidity during the drying stage. Dust can cause significant defects visible to the naked eye, such as white spots, dents, and indentations. High humidity can cause the adhesive surface to turn white, bubbles to form in the adhesive layer, and delamination. Inappropriate temperature can result in orange peel texture, uneven thickness, and cross-contamination of the adhesive.

[0040] Secondly, UV pre-curing can maintain the smooth surface of the encapsulant after pressing. When heat curing is performed, the encapsulant has already gelled, and the internal stress of shrinkage is small. Unlike full UV curing, it will not have defects such as ripples or orange peel due to instantaneous volume shrinkage. The smoothness of the encapsulant can even exceed the limit that can be achieved by pure heat curing.

[0041] Third, since UV curing + thermal curing primarily relies on thermal curing, UV dual-curing adhesives can be supplemented with frosting powder, diffusion particles, and colorants as needed. These added materials do not block UV light, allowing for precise control of the encapsulating adhesive's haze, gloss, and diffuse reflection properties. This further enriches the types of products that can be prepared using the process.

[0042] In summary, a more efficient manufacturing process can support LED displays with higher optical performance. Optical performance includes indicators such as haze, transmittance, surface texture, sharpness, color coordinate shift, and surface roughness. Of course, surface flatness is also an important indicator for evaluating an LED display.

[0043] The core of LED packaging technology is to encapsulate the surface of the LED unit board with adhesive to achieve a smooth adhesive surface and a frosted optical finish. To achieve the desired technical effect, the aforementioned steps S1 to S9 have the following specific settings.

[0044] In S1, the release film usually contains dust. If the release film contains dust, the encapsulant will develop pits or be covered with foreign matter after curing. Similarly, the LED unit board usually contains grease. If the LED unit board contains grease, the encapsulant will also develop pits or be covered with foreign matter after curing. Therefore, it is necessary to clean both the release film and the LED unit board.

[0045] Specifically, the LED unit boards will be cleaned of grease using an ultrasonic cleaner, which can be a standalone machine or a production line.

[0046] When using a single machine, it is necessary to control the turnaround time of the LED unit board, for example, between 3 and 6 hours. At the same time, it is also necessary to maintain the cleanliness of the production workshop, the cleanliness of the production personnel, and the cleanliness of the production equipment. In addition, before the LED unit board is loaded, the dust adsorbed on the surface can be removed by an ion fan.

[0047] When using an assembly line, an ion bar can be installed at the connection between the ultrasonic cleaner and subsequent equipment to remove dust adsorbed on the surface of the LED unit board.

[0048] Specifically, the cleaning method for release film needs to be selected according to the packaging form of the release film. Due to different packaging forms, the way the release film is fed onto the carrier film fixture is also different, and cleaning needs to be carried out at the same time as feeding.

[0049] If the release film is a roll material, a roller-pressed film application method will be used. An ionizing air bar will be installed above the release film and before it enters the carrier film fixture to reduce dust adsorption on the release film.

[0050] If the release film is a sheet, when taking out a single sheet, an ion fan will blow air on the side or top of the stack of sheets to allow adjacent sheets to separate naturally. After separation, the ion fan will then blow air on the side of the sheet that was originally attached to other sheets.

[0051] As the LED display packaging process in this application involves multiple steps, each with different process conditions, these steps are typically performed at different workstations. To facilitate faster switching between these steps, the workstations are arranged horizontally and linearly. Based on this, linear conveyor lines are used to transfer the film carrier fixtures; for example, double-speed chain conveyors, roller conveyors, and synchronous belt conveyors can be selected.

[0052] To accommodate large-scale, high-volume production lines, the release film is in roll form. Meanwhile, the release film laying process between S1 and S2 is achieved through the coordinated operation of a roller pressing machine and a vacuum adsorption machine. The synergy between the roller pressing machine and the vacuum adsorption machine ensures the release film is laid more smoothly and accurately in the predetermined position on the carrier fixture, and further improves the efficiency of the process. This efficiency refers to the rapid and smooth locking and unlocking of the carrier fixture at each station.

[0053] Specifically, the release film will be laid using the following steps: S101. The position lock of the carrier film fixture is performed by vacuum adsorption. S102. With an air suspension layer above the carrier film fixture, the release film is transferred to a predetermined position above the carrier film fixture. S103. Roll the release film from the direction away from the release film roll to the direction close to the release film roll. During the rolling process, the area on the carrier film fixture where the release film is attached is vacuum-adsorbed, while the area on the carrier film fixture where the release film is not attached is under normal pressure. S104. Vacuum adsorption is used to make the release film adhere tightly to the edge of the carrier film fixture; S105. Cut the release film; S106. Allow the release film on the carrier film fixture to stand for a period of time.

[0054] The vacuum adsorption equipment includes a vacuum adsorption platform and a vacuum pump. The vacuum adsorption platform is a marble or aluminum alloy plate with micropores or grooves, and the surface is covered with a layer of breathable microporous ceramic plate or porous metal plate.

[0055] The roll-pressing film application equipment includes a roll of release film, pressure rollers, a robotic arm, and a cutting knife. The roll of release film is used to load the rewound release film. The pressure rollers press down on the release film to complete the application. The robotic arm grasps the head of the release film roll to gradually feed the release film off the roll of release film. The cutting knife... In S101, the position and orientation locking process of the carrier film fixture refers to the following: when the conveyor line transports the carrier film fixture to the film laying station, the conveyor line stops working, and then the vacuum adsorption platform lifts upward, causing the carrier film fixture to detach from the conveyor line. Then, the vacuum adsorption platform turns on the vacuum to firmly adsorb the carrier film fixture. At this time, the carrier film fixture can be in a temporarily fixed state, which is equivalent to locking the position and orientation.

[0056] Based on the pose-locking process, the positional stability of the carrier film fixture can be enhanced during the subsequent laying of the release film. Enhanced positional stability means that the mechanical environment experienced by the release film during laying is relatively uniform; only the roller pressing equipment applies the laying-related forces to the release film, thus making it easier to lay the release film more smoothly and with higher positional accuracy.

[0057] In step S102, since it is impossible to transfer the release film to the predetermined position on the carrier fixture in one go, an air suspension layer is used to temporarily suspend the release film on the surface of the carrier fixture. At this time, the robot can fine-tune the position of the release film, thereby accurately laying the release film in the available position on the carrier fixture. The air suspension layer can be formed by an air passage located outside the edge of the upper surface of the carrier fixture in the vacuum adsorption platform. The airflow is sprayed upward from the outer edge of the carrier fixture, thus forming an air suspension layer similar to an air cushion structure.

[0058] Based on the air suspension layer, when fine-tuning the release film, the release film will not adhere to the carrier film fixture due to the electrostatic adsorption between the release film and the carrier film fixture, thus avoiding defects such as stretching, deformation or wrinkles, and promoting the smooth laying of the release film.

[0059] In other embodiments, the air suspension layer can be achieved without the air path of the vacuum adsorption platform. For example, a separate air nozzle can be used. Specifically, the air nozzle is installed in front of the pressing roller, meaning on the side of the pressing roller away from the roll shaft, and also above the carrier fixture. During operation, the airflow from the nozzle blows towards the edge of the release film's upper surface to form an air suspension layer between the release film and the carrier fixture surface.

[0060] To avoid significant disturbance to the release film by the air suspension layer, which could lead to uneven laying of the release film later, the height of the air suspension layer should be approximately 0.2-0.5 mm. Simultaneously, the air flotation pressure is extremely low, ranging from 0.05-0.1 MPa.

[0061] In step S103, the pressing roller first presses down on the release film, and then moves towards the roll shaft to achieve the laying. Furthermore, during the roller pressing process, in order to achieve a release film surface free of air bubbles and wrinkles, it is necessary to promptly expel the air between the release film and the carrier film fixture, while simultaneously maintaining the stability of the carrier film fixture's position throughout this process.

[0062] Specifically, during the rolling process, the area on the carrier film fixture where the release film is attached is vacuum-adsorbed, while the area on the carrier film fixture where the release film is not attached is under normal pressure. Figure 2In the diagram, area A is the area where the carrier film fixture is located, area B is the area where the release film has been applied, area C is the area where the release film has not been applied, and D is the direction of movement of the pressure roller. Area B will be in a vacuum state, and area C will be in a normal pressure state.

[0063] Based on this zoned vacuum control method, the carrier film fixture is always held in place by the vacuum, thus ensuring the stability of the carrier film fixture's position during the film application process. While the vacuum adsorption platform holds the carrier film fixture, the vacuum negative pressure field can be applied to the release film from the space between the vacuum adsorption platform and the carrier film fixture, thereby indirectly adsorbing the release film onto the carrier film fixture.

[0064] Based on this indirect method of adsorbing the release film onto the carrier fixture, negative pressure can be used to balance the tensile stress on the release film. This tensile stress arises from the electrostatic attraction between the release film and the carrier fixture, creating a rebound stress that can cause the release film to wrinkle. Therefore, by balancing with negative pressure, micro-wrinkles and minor displacements of the release film can be prevented. Areas where the release film has not yet been properly applied are kept at normal pressure to prevent premature contact between the release film and the carrier fixture, which could trap a large amount of air and form air bubbles that cannot be eliminated later. This promotes a smoother application of the release film.

[0065] In S104, the vacuum adsorption platform has a membrane-cutting auxiliary adsorption area located outside the edge of the membrane carrier fixture. Figure 2 In the diagram, area E refers to the release film suction area. The upper surface of the release film suction area is flush with the upper surface of the carrier film fixture. The release film suction area adsorbs the area of ​​the release film near the edge of the carrier film fixture and near the roll shaft, so that the release film in this area is tightly attached to the carrier film fixture. Then, in S105, the release film is cut with a film cutting knife.

[0066] Based on the setting of the film-cutting auxiliary suction area, the release film will temporarily be in a state similar to a "rigid plate," which can provide a stable cutting environment for the film-cutting knife. Therefore, after cutting, it is less likely to have uneven cut edges or curling, and it is also less likely to have release film displacement or stretching deformation.

[0067] In S106, considering that some release films are easily stretched, the release film will be left to stand on the carrier film fixture for a period of time after laying, for example, 10-15 seconds. This allows the release film to relax and rebound.

[0068] In summary, based on the relevant precautions mentioned in each step from S101 to S106, the core purpose of these precautions is to maintain the flatness and positional accuracy of the release film while achieving large-scale, high-volume production.

[0069] In other embodiments, if high-volume production is not considered, the release film can be made of sheet material. During installation, one end of the release film is aligned with the edge of the carrier fixture to form the starting end. Simultaneously, a clean, long ruler or scraper is used to slowly and continuously scrape and press the film in one direction from the fixed starting end towards the other end. In summary, using sheet material for installation makes it easier to achieve a smooth finish, but the production efficiency is relatively low.

[0070] In S2, the core functions of the damming adhesive are as follows: First, constraining the adhesive coverage: In S3, the adhesive sprayed onto the release film is liquid and has fluidity. Without damming adhesive, the encapsulating adhesive would spread randomly on the release film, resulting in uneven adhesive layer thickness and irregular edges. By constraining the adhesive coverage, the encapsulating adhesive thickness on the LED unit board can be made uniform.

[0071] Secondly, it optimizes optical effects: Without damming adhesive, during the S6 lamination process, the edges of the encapsulant naturally form smooth slopes or thin edges, resembling the shape of a water droplet. During subsequent UV curing, this uneven thickness causes irregular refraction and scattering of light at the edges, potentially resulting in bright edges, halos, or color differences on the edges of each LED unit in the final display. Damming adhesive provides a boundary, forcing the encapsulant to have neat edges and clear thickness abrupt changes after lamination. After removing the damming adhesive, the edges of the encapsulant are clean, sharp vertical surfaces, which positively impacts the uniformity and consistency of light emission.

[0072] Third, improved structural stability: Without damming adhesive, during S6 lamination, the LED unit board is directly pressed onto a layer of encapsulating adhesive. The adhesive is fluid, and the LED unit board may tilt, wobble, or drift like on a "waterbed," resulting in inaccurate bonding and uneven adhesive layer thickness. Damming adhesive, after curing, has a certain height and hardness, acting like a temporary, precise leveling block. It determines the final thickness limit of the encapsulating adhesive after pressing, thus ensuring that the LED unit board is pressed horizontally, stably, and precisely positioned.

[0073] Based on the three functions of the aforementioned damming adhesive, its coordination with other steps in the process, and considering production efficiency, the following precautions should be taken when using the damming adhesive in S2: First, the damming adhesive needs to be light-transmitting so that UV light can fully irradiate the encapsulating adhesive during the subsequent S7 process.

[0074] Secondly, to maximize the amount of encapsulating adhesive within a limited area, the dam is designed with a width slightly greater than its height. This top-narrow, bottom-wide structure provides stronger support. This structural characteristic helps resist the hydrostatic pressure generated by the encapsulating adhesive during step S3. During step S6, the inner slope guides the encapsulating adhesive upwards, allowing it to fill the tiny gaps at the bottom and sides of the LED unit board. In step S6, sufficient support resists the pressure transmitted from the LED unit board through the encapsulating adhesive, helping to maintain consistent adhesive thickness. The larger space on the upper side of the dam during step S6 provides room for air bubbles to escape, reducing the complexity of subsequent leveling processes.

[0075] Meanwhile, based on the structure of the damming adhesive being narrow at the top and wide at the bottom, the cross-section of the damming adhesive can be trapezoidal or semi-circular. The trapezoidal shape is the easiest to apply and form, while the semi-circular shape can further enhance the impact resistance of the damming adhesive.

[0076] Third, to prevent stringing and dripping during the dispensing process to form the damming adhesive, and to ensure it thins during extrusion and thickens rapidly upon settling, a medium viscosity and high thixotropic adhesive is chosen. Specifically, if the damming adhesive is a hot melt adhesive, its viscosity at 160°C is 3500-8000 mPa·s, and its thixotropic index is 3-5. If the damming adhesive is a thermosetting adhesive, its viscosity at 25°C is 20000-50000 mPa·s, and its thixotropic index is 3-5. If the damming adhesive is a UV adhesive, its viscosity at 25°C is 8000-15000 mPa·s, and its thixotropic index is 3-5.

[0077] Regarding the selection of the damming adhesive, if a hot melt adhesive is used, it can naturally cool and cure after extrusion, resulting in high production efficiency and low production costs, making it suitable for large-scale automated production. If a thermosetting adhesive is used, it offers high reliability and is suitable for harsh working conditions. If a UV adhesive is used, it provides a flexible process window, making it suitable for high-precision continuous production. In this embodiment, due to the aforementioned need to adapt to large-scale, high-volume production lines, a hot melt adhesive is preferred for the damming adhesive. Subsequent process steps will be described using a hot melt adhesive as an example.

[0078] Fourth, in order to achieve complete closure of the annular area during the dispensing process to form the dammed adhesive, and to prevent the dammed adhesive from splashing into the predetermined area within the ring, which is the area where the encapsulating adhesive will be applied later, the dispensing valve needs to be selected carefully. Specifically, if the dispensing valve is a piezoelectric jet valve, during dispensing, the impactor moves without impacting the nozzle seat, forming a pre-filled adhesive droplet on the outside of the nozzle. Then, the impactor strikes the nozzle seat at high speed, forming a complete main adhesive droplet on the outside of the nozzle. If the dispensing valve is a back suction valve, after dispensing, the outside of the nozzle is cleaned.

[0079] Based on the two options mentioned above, if a piezoelectric jet valve is selected, firstly, a closed annular adhesive strip can be formed by high-frequency jetting of continuous adhesive dots. Secondly, near-field jetting, where the nozzle of the dispensing valve is closer to the release film, combined with a method of gently pushing the ejector pin followed by high-speed movement of the ejector pin, prevents the adhesive droplet from breaking into satellite dots at the tail, thus preventing dammed adhesive from splashing into the annular area. If a back-suction valve is selected, firstly, the annular area can be completely closed using an overlapping initiation method. Secondly, since the adhesive is extruded, timely cleaning of the nozzle after each dispensing can prevent dammed adhesive from splashing into the annular area.

[0080] The choice between a piezoelectric spray valve and a back-suction valve depends on the specific work scenario. If the process conditions are relatively simple and fine adjustment of the dispensing valve is not possible, a back-suction valve is recommended. If the working conditions are sufficient, the work cycle is high, and fine adjustment of the dispensing valve is possible, a piezoelectric spray valve is recommended. In some high-end manufacturing scenarios, a combination of a piezoelectric spray valve, UV adhesive, and on-the-fly pre-curing is used. This ensures perfect dam closure and achieves zero splashing and zero contact damage. On-the-fly pre-curing refers to the installation of a UV lamp at the dispensing valve to achieve simultaneous dispensing and curing.

[0081] In summary, based on the four points of attention mentioned above regarding the dam sealant, these four points are not independent and unrelated to each other, nor are they simply mutually exclusive with other steps. In other words, not each point of attention alone promotes the entire process.

[0082] Specifically, the reason for using a transparent adhesive for the damming sealant is as follows: If the damming sealant were opaque, a special resin system would be required, such as a UV adhesive with a cationic curing system, which also has dark curing properties. However, using such an adhesive, while meeting the requirements of high thixotropy and medium viscosity, would result in a very complex adhesive formulation, and ensuring the stability of the bonding interface strength between the damming sealant and the encapsulating adhesive would be difficult to control, leading to an overly complex process. Therefore, using a transparent adhesive for the damming sealant simplifies the encapsulation process while achieving both high thixotropy and medium viscosity, and also ensures a more stable bonding strength between the damming sealant and the encapsulating adhesive.

[0083] The reason why damming adhesives need to have high thixotropy and medium viscosity is that, based on these two characteristics, damming adhesives can achieve four properties: no stringing, no dripping, shear thinning during extrusion, and rapid thickening after settling.

[0084] Based on these four characteristics, piezoelectric jet valves and back suction valves can be selected for dispensing. The piezoelectric jet valve, based on the dispensing working principle, can achieve complete closure of the annular area of ​​the dammed adhesive through precise control, without splashing into the inner area of ​​the ring. The back suction valve, based on the dispensing working principle, can also achieve complete closure of the annular area of ​​the dammed adhesive without splashing into the inner area of ​​the ring under low-frequency operation.

[0085] Because piezoelectric injection valves and back suction valves can better form dammed adhesive, the shape of the dammed adhesive can be better achieved. For example, the width and height of the dammed adhesive are highly consistent, meaning that the width and height errors between different positions are very small, thus enabling the dammed adhesive with a trapezoidal or semi-circular cross-section to be achieved.

[0086] In summary, the adhesive is the "internal factor," the dispensing valve is the "actuator," and the shape of the dammed adhesive is the "result and guarantee." A defect in any one of these links will negate the efforts of the other two.

[0087] In S3, precise control of various parameters of the encapsulating adhesive is required.

[0088] For example, the dimensional fit between the encapsulating adhesive and the damming adhesive needs to be precisely controlled. Specifically, the height of the encapsulating adhesive is slightly lower than the height of the damming adhesive. For instance, when the thickness of the encapsulating adhesive is 1.5mm, the damming adhesive is typically 0.1-0.3mm higher than the encapsulating adhesive. There is a gap between the encapsulating adhesive and the damming adhesive; for example, the gap between the encapsulating adhesive and the damming adhesive can be between 15mm and 25mm.

[0089] For example, the amount of encapsulating adhesive needs to be precise. Too much adhesive will cause it to overflow beyond the surrounding adhesive after S6, while too little will result in insufficient adhesive at the edges of the LED unit board, easily leading to air bubbles or voids. The amount of encapsulating adhesive depends on the specifications and shape of the LED unit board.

[0090] For example, the encapsulating adhesive needs to flow naturally to ensure that the thickness of the encapsulating adhesive remains uniform after the lamination process.

[0091] To improve the leveling effect of encapsulating adhesives, the viscosity of the adhesive can be considered. If the adhesive is a one-component adhesive, a moderate viscosity is preferred, such as one between 1000-5000 cps. If the adhesive is a two-component adhesive, the viscosity can be reduced by decreasing the proportion of the curing agent / hardener / catalyst. However, for two-component adhesives, thorough and uniform mixing often has a more direct impact on improving the leveling effect.

[0092] Regarding how to promote the leveling of the encapsulating adhesive, we can also consider the process conditions before dispensing. For example, before S3, the adhesive can be degassed to remove tiny air bubbles. Degasting can be achieved by vacuum degasing using a vacuum degasing machine, or by centrifugal degasing, ultrasonic degasing, and thermal degasing.

[0093] Vacuum degassing is a widely used and reliable method. Centrifugal degassing is highly efficient and suitable for UV adhesives. Ultrasonic degassing is more suitable for lower viscosity adhesives, but its effect on high viscosity adhesives is slightly worse. Heating degassing is usually only used as an auxiliary method and not used alone. Therefore, in this embodiment, vacuum degassing and centrifugal degassing are preferred.

[0094] To promote the leveling of the encapsulating adhesive, one can consider the process conditions after dispensing. For example, after S3 and before S4, vacuum treatment can be applied to the encapsulating adhesive, using the negative pressure of the vacuum to promote leveling. This also helps to remove air bubbles.

[0095] It also promotes the leveling of the encapsulating adhesive, which not only facilitates step S3 but also promotes other steps in the process.

[0096] For step S6: Since the encapsulating adhesive uses a medium viscosity, it can flow fully and fill the LED unit board during lamination without excessive overflowing beyond the surrounding adhesive. Because the adhesive undergoes degassing treatment before dispensing, the vacuum process during lamination only needs to remove air bubbles at the interface between the LED unit board and the encapsulating adhesive. Since the encapsulating adhesive has undergone leveling treatment, it is already relatively smooth during lamination, requiring only minimal pressure to achieve uniform contact with the LED unit board, reducing the risk of stress damage to the LED chip.

[0097] For step S7: Because the encapsulating adhesive uses a medium viscosity, the adhesive layer thickness is more uniform. Therefore, during UV treatment, the UV light penetration path is consistent, improving curing uniformity. Since the adhesive undergoes degassing treatment before dispensing, it will not form "white spots" or "spots" due to heat expansion during UV treatment. Because the encapsulating adhesive undergoes leveling treatment, it can cure in a smoother state under UV light, resulting in more uniform refraction and reflection of UV light, thus allowing for more even curing.

[0098] In summary, by optimizing the formulation of the encapsulating adhesive and the processes before and after dispensing, the entire process can have a larger process window and a higher yield.

[0099] In other embodiments, the leveling of the encapsulating adhesive can be promoted by the following measures: dispensing the encapsulating adhesive in stages; allowing it to stand for a predetermined time after dispensing, such as 2-5 minutes; or vibrating the encapsulating adhesive using a micro-vibration platform after dispensing.

[0100] In step S4, a carrier board fixture is required, and the reason why the carrier film fixture needs to be assembled with the carrier board fixture is as follows: In step S5, the encapsulating adhesive needs to be vacuum-degassed to remove air bubbles. At this time, the LED unit board cannot be connected to the encapsulating adhesive yet. However, after completing step S5, the encapsulating adhesive needs to be kept free of air bubbles before proceeding to step S6. Therefore, a carrier board fixture is needed to load the LED unit board, allowing the LED unit board and the encapsulating adhesive to be positioned relative to each other and spaced apart. Simultaneously, during step S7, a predetermined clamping force needs to be maintained between the carrier film fixture and the carrier board fixture, so the carrier film fixture needs to be assembled with the carrier board fixture.

[0101] The reason why the carrier film fixture and the carrier board fixture need to be assembled is that, although a predetermined pressure can be continuously applied to the LED unit board by a pressing mechanism that moves with the carrier film fixture, it is difficult to control the relative position change between the LED single board and the encapsulating glue in this way, and such a fitting structure would be very large and would not be able to be used in a UV curing oven.

[0102] Regarding how the carrier film fixture and the carrier plate fixture maintain a predetermined clamping force, specifically, the carrier plate fixture and the carrier film fixture can slide closer or further apart through guide rods, and are equipped with mounting rods and spring pins. The mounting rod is a spring telescopic rod, which is used to connect the LED unit board.

[0103] During S6, when the carrier plate fixture moves a predetermined distance closer to the carrier film fixture, the spring pin locks the position between the carrier plate fixture and the carrier film fixture. At this time, the mounting rod is in a retracted state. The retracted mounting rod can apply a predetermined pressure to the LED unit board to achieve the aforementioned predetermined clamping force between the carrier film fixture and the carrier plate fixture.

[0104] In summary, the assembly of the film carrier fixture and the plate carrier fixture provides the motion basis required for subsequent process steps, and also serves as a retainer.

[0105] After completing S4, the gap between the LED unit board and the encapsulating adhesive is very small, making it impossible to perform any processing on the LED unit board at this point. However, in the LED packaging process, it is not only necessary to precisely control the parameters of the encapsulating adhesive, but also the parameters of the LED unit board. The cleaning process for the LED unit board mentioned in S1 is to control the surface cleanliness of the LED unit board. In order to further promote the bonding strength between the LED unit board and the encapsulating adhesive, special treatment of the surface of the LED unit board to be bonded is required before S4.

[0106] Specifically, before S4, the LED unit board undergoes plasma treatment, where the gas used for plasma treatment is a mixture of argon and oxygen, with a volume ratio of argon to oxygen of 8:1-10:1.

[0107] Based on the aforementioned treatment methods, the following benefits are achieved for LED unit boards: First, plasma treatment can remove extremely small contaminants to achieve high microscopic cleanliness and also increase tensile strength, promoting subsequent coating and bonding processes, resulting in better coating adhesion and stronger bonding. Second, the use of a mixture of argon and oxygen, where argon primarily performs physical roughening, increasing surface microscopic roughness through physical bombardment to provide more bonding area for the adhesive, and oxygen primarily performs chemical activation, using chemical oxidation to introduce polar groups such as hydroxyl groups, increasing surface energy and allowing the adhesive to better wet and spread.

[0108] The equipment used for plasma processing can be either a rotary nozzle or an array plasma source. Rotary nozzles are more commonly used in continuous production lines, while array plasma sources are more commonly used in precision parts.

[0109] In summary, plasma treatment promotes the surface adhesion of LED unit boards, thereby improving the fit between the LED unit boards and the encapsulating adhesive after bonding.

[0110] In S5, the core purpose of vacuum treatment is to remove interface bubbles. The interface refers to the contact surface between the LED unit board and the encapsulating adhesive. These bubbles are formed because air is trapped due to the microscopic unevenness of the LED unit board surface when they come into contact with the adhesive. The purpose of vacuum treatment is to reduce the density of air molecules in the lamination environment. Air is no longer a "continuous medium" but rather a group of sparse, almost non-colliding isolated molecules. At this point, the situation of "a continuous layer of air between the interfaces" no longer exists. This reduces the operational difficulty of the subsequent lamination process in S6.

[0111] In S6, during the lamination process, it's crucial to consider how the pressure should be distributed and how it should vary. Specifically, regarding pressure distribution, for a single LED unit board, the lamination pressure needs to be evenly distributed to avoid excessive local pressure that could damage the LED chips or cause uneven adhesive layer thickness. Since a single lamination process can handle more than one LED unit board, the lamination pressure also needs to be uniform to achieve high-quality processing of multiple LED unit boards simultaneously.

[0112] Regarding how the pressure should be varied, a method of first applying low pressure, then increasing pressure, then maintaining pressure, and finally releasing pressure in stages will be adopted. Specifically, the initial low pressure allows the encapsulating adhesive to spread slowly, giving air bubbles enough time to escape and preventing instantaneous high pressure from trapping air bubbles within the adhesive layer. Based on the vacuum treatment performed in S5 mentioned above, low-pressure spreading is necessary to achieve its technical effect, or in other words, the effect achieved by low-pressure spreading can better meet expectations.

[0113] The mid-stage pressurization provides sufficient power to force the adhesive into the bottom of the LED beads and the dense gaps, achieving void-free filling. Pressure holding allows the encapsulating adhesive to flow and initially set under pressure. Stepped pressure release prevents the encapsulating adhesive from rebounding due to sudden pressure changes, avoiding the formation of new microbubbles or separation of the encapsulating adhesive from the LED unit board.

[0114] The device that achieves this pressure change can be an airbag, a cylinder with a proportional valve, a hydraulic servo system, or even a mechanical pressure device.

[0115] Considering the equipment cost and the difficulty of implementing pressure changes, airbags are preferred for the pressing process. Airbags can achieve the aforementioned low pressure, pressure increase, pressure holding, and stepped pressure release through internal pressure changes. This internal pressure variation also allows for adaptation to LED unit boards of different thicknesses.

[0116] In summary, based on the aforementioned optimization of the encapsulating adhesive and environmental treatment before lamination, combined with a special lamination process, a simpler and more flexible approach can be adopted to improve the molding quality of the encapsulating adhesive on the LED unit board, thereby further enhancing the quality of the LED display screen.

[0117] In S7, the purpose of UV curing is to set the encapsulating adhesive gel. Therefore, the UV light irradiation is only for a short time. The duration of irradiation depends on factors such as the thickness of the encapsulating adhesive, its formulation, and the parameters of the UV light. Specifically, in this application, the thickness of the encapsulating adhesive is between 1mm and 2mm, the UV light irradiation distance is 20cm, the wavelength of the UV light is 365nm or 395nm, the light intensity is 3000mW / cm², and the luminous flux is 2700mJ / cm². In this case, the UV light irradiation time can be between 0.5 and 2 seconds.

[0118] In addition, during UV curing, attention must be paid to the uniformity of light. Typically, the carrier film fixture is a glass carrier to further increase light transmittance. Furthermore, in the UV curing oven, the encapsulating adhesive is cured in all directions by light sources installed at different positions in the oven.

[0119] During UV curing, the adhesive undergoes chemical shrinkage, and the LED unit board, release film, and encapsulating adhesive all expand thermally due to increased temperature. Therefore, after S7, if the fixture is removed at high temperature, the encapsulating adhesive is still in a relatively soft and malleable state. Once the fixture is removed, the internal stress generated by the cooling and shrinkage of the LED unit board, release film, and encapsulating adhesive will be released unevenly, resulting in: overall warping of the LED unit board, deterioration of the surface flatness of the encapsulating adhesive, and peeling or micro-cracks at the edges of the encapsulating adhesive.

[0120] Based on the reasons described above, after S7 and before S8, a cooling process is performed until the gel strength and coefficient of thermal expansion of the encapsulating adhesive reach the predetermined values. Then, the self-pressing between the carrier board fixture and the carrier film fixture is released, and the carrier board fixture is then allowed to cover the LED unit board for a predetermined time until the final thermal equilibrium and stress release are achieved.

[0121] The cooling process can enhance the gel strength, making the encapsulating adhesive strong enough to resist mechanical disturbances. After the cooling process, the temperature of the three layers—LED unit board, release film, and encapsulating adhesive—is kept constant, reducing thermal deformation.

[0122] This involves releasing the self-pressurization between the carrier plate fixture and the carrier film fixture, which means releasing the locking caused by the aforementioned spring pin, so that the distance between the carrier plate fixture and the carrier film fixture can be restored to the initial state. The so-called initial state is the state of the carrier plate fixture and the carrier film fixture under the gravitational field.

[0123] The process of covering the LED unit board with the carrier fixture for a predetermined time utilizes the fixture's own weight to achieve final thermal equilibrium and counteract stress, thereby further preventing warping. Specifically, the covering time can be between 10 and 20 seconds.

[0124] In S9, during the thermosetting process, the release film, LED unit board, and encapsulating adhesive are processed together. The release film serves as temporary support to prevent deformation of the assembly formed by the encapsulating adhesive and LED unit board, and also protects the adhesive surface from contamination.

[0125] Finally, after the thermosetting process is complete, the release film is peeled off.

[0126] The implementation principle of the LED display encapsulation process in this application embodiment is based on the premise that the adhesive is a UV dual-curing adhesive. First, after lamination, UV curing can be used to gel and set the encapsulating adhesive, which can then be directly heat-cured. This process eliminates the drying step, making the process faster and avoiding the adverse effects of dust accumulation and environmental temperature and humidity during the drying stage. Second, UV pre-curing maintains the smooth surface of the encapsulating adhesive after lamination. During subsequent heat curing, the encapsulating adhesive has already gelled, resulting in lower internal stress and preventing defects such as ripples or orange peel caused by instantaneous volume shrinkage, as seen in full UV curing. The final smoothness of the encapsulating adhesive can even exceed the limits achievable by pure heat curing. Third, because UV curing + heat curing primarily relies on heat curing, the UV dual-curing adhesive can be supplemented with frosting powder, diffusion particles, and colorants as needed. These do not block UV light, allowing for precise control of the encapsulating adhesive's haze, gloss, and diffuse reflection characteristics.

[0127] This application also discloses an LED display screen. The LED display screen is manufactured using the packaging process mentioned in the foregoing embodiments.

[0128] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. An LED display packaging process, characterized in that: Includes the following steps: S1. Clean the release film and LED unit board; S2. The release film laid on the carrier film fixture is dammed to form a damming adhesive, wherein the inner side of the damming adhesive forms a unit bonding area for LED unit boards to be bonded. S3. A potting process is performed in the unit bonding area of ​​the release film to form an encapsulating adhesive, wherein the adhesive is a UV dual-curing adhesive. S4. Assemble the carrier board fixture containing the LED unit board and the carrier film fixture with the release film, so that the LED unit board and the encapsulating adhesive are arranged in a spaced-out relative manner. S5. Vacuum degassing treatment is performed on the encapsulating adhesive; S6. Press the carrier board fixture in a vacuum environment to connect the LED unit board with the encapsulating adhesive. S7. While maintaining a predetermined clamping force between the carrier plate fixture and the carrier film fixture, perform UV curing treatment on the encapsulating adhesive. S8. Remove the carrier plate fixture and film carrier fixture; S9. Perform thermosetting treatment on the encapsulating adhesive.

2. The LED display packaging process according to claim 1, characterized in that: The film carrier fixture is a carrier used on a linear conveyor line. In S1, if the release film is a roll, the release film laying process between S1 and S2 is achieved by the coordinated operation of a roll-pressing film laminating device and a vacuum adsorption device. Specifically, the release film laying adopts the following steps: S101. The position lock of the carrier film fixture is performed by vacuum adsorption. S102. With an air suspension layer above the carrier film fixture, the release film is transferred to a predetermined position above the carrier film fixture. S103. Roll the release film from the direction away from the release film roll to the direction close to the release film roll. During the rolling process, the area on the carrier film fixture where the release film is attached is vacuum-adsorbed, while the area on the carrier film fixture where the release film is not attached is under normal pressure. S104. Vacuum adsorption is used to make the release film adhere tightly to the edge of the carrier film fixture; S105. Cut the release film; S106. Allow the release film on the carrier film fixture to stand for a period of time.

3. The LED display packaging process according to claim 1, characterized in that: In S2, the cross-section of the dammed rubber is trapezoidal or semi-circular, narrower at the top and wider at the bottom.

4. The LED display packaging process according to claim 3, characterized in that: In S2, if the damming adhesive is a hot melt adhesive, the viscosity of the damming adhesive is 3500-8000 mPa·s at 160℃, and the thixotropic index is between 3 and 5; if the damming adhesive is a thermosetting adhesive, the viscosity of the damming adhesive is 20000-50000 mPa·s at 25℃, and the thixotropic index is between 3 and 5; if the damming adhesive is a UV adhesive, the viscosity of the damming adhesive is 8000-15000 mPa·s at 25℃, and the thixotropic index is between 3 and 5.

5. The LED display packaging process according to claim 4, characterized in that: In S2, if the dispensing valve is a piezoelectric jet valve, during dispensing, the ejector pin is moved first without hitting the nozzle seat, so that a pre-filled glue droplet is formed on the outside of the nozzle. Then, the ejector pin hits the nozzle seat at high speed, so that a complete main glue droplet is formed on the outside of the nozzle. If the dispensing valve is a back suction valve, after dispensing is completed, the outside of the nozzle is cleaned.

6. The LED display packaging process according to claim 5, characterized in that: Before step S3, the adhesive is degassed; after step S3 and before step S4, the encapsulating adhesive is vacuum treated.

7. The LED display packaging process according to claim 6, characterized in that: Before step S4, the LED unit board is subjected to plasma treatment, wherein the gas used for plasma treatment is a mixture of argon and oxygen, and the volume ratio of argon to oxygen is 8:1-10:

1.

8. The LED display packaging process according to claim 6, characterized in that: In S6, an airbag is used for the pressing process. The pressure change during the pressing process is as follows: first low pressure, then high pressure, then pressure holding, and finally step-by-step pressure release.

9. The LED display packaging process according to claim 6, characterized in that: After S7 and before S8, a cooling process is performed until the gel strength and coefficient of thermal expansion of the encapsulating adhesive reach a predetermined value. Then, the self-pressurization between the carrier plate fixture and the carrier film fixture is released. The carrier plate fixture is then allowed to cover the LED unit board for a predetermined time until the final thermal equilibrium and stress release are achieved.

10. An LED display screen, characterized in that: It is manufactured using the LED display packaging process described in any one of claims 1-9.

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