LED display packaging method

Abstract

This invention provides an LED display packaging method, comprising: forming a first encapsulating layer and a second encapsulating layer on a lamp board, wherein the first encapsulating layer is formed on the lamp board by heating to soften and then pressing it into the gap space between a plurality of LED beads on the lamp board; the thickness of the first encapsulating layer located above the top surface of the LED beads is 0-10 μm; the second encapsulating layer is located on the side of the first encapsulating layer opposite to the lamp board and covers the LED beads; the first encapsulating layer can block light, and the second encapsulating layer allows light emitted by the LED beads to pass through. This LED display packaging method reduces process difficulty and manufacturing cost, improves the consistency of the black background effect, improves the light extraction efficiency of the LED display, and reduces the power consumption of the LED display.

Description

Technical Field

[0001] This invention belongs to the field of LED display technology, and particularly relates to an LED display packaging method. Background Technology

[0002] LED (Light Emitting Diode) displays feature high brightness, vibrant colors, high luminous efficiency, high contrast, short response time, wide operating temperature range, and low energy consumption. They are widely used in stage display equipment, advertising display equipment, data visualization display equipment, and commercial display equipment.

[0003] An LED display screen consists of multiple independent cabinets connected in sequence and spliced ​​together from multiple light boards. Each light board includes a PCB (Printed Circuit Board) and several independent LED beads set on the PCB. This special structure gives the LED display screen the significant advantages of being able to be flexibly applied in a variety of usage scenarios and having a high degree of overall display integrity.

[0004] In recent years, Micro LED displays, employing COB (Chip on Board) and MIP (Mini / Micro LED in Package) technologies, have emerged in the industry. Micro LED displays use chip-level LED pixels. In terms of manufacturing, multiple chip-level LED pixels are first bonded onto a PCB, and then the entire LED board is packaged. Compared to traditional SMD LED displays, Micro LED displays have a shorter process chain and are easier to achieve ultra-small pitch. However, new technical challenges have also arisen. Besides the complex and costly molding process, the small size of the LED pixels in Micro LED displays means that a large portion of the PCB area is covered by solder resist ink. The solder resist ink can exhibit color differences between boards, leading to a significant problem of inconsistent base color in Micro LED displays. Summary of the Invention

[0005] The purpose of this invention is to provide an LED display packaging method that aims to solve the technical problems of complex processes, high costs, and poor consistency of background color in current related technologies.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for packaging an LED display screen is provided, comprising:

[0008] A first encapsulating layer and a second encapsulating layer are formed on the lamp board. The first encapsulating layer is formed on the lamp board by heating it to soften and then pressing it into the gap space between a plurality of lamp beads on the lamp board. The thickness of the first encapsulating layer located above the top surface of the lamp beads is 0-10 μm. The second encapsulating layer is located on the side of the first encapsulating layer opposite to the lamp board and covers the lamp beads. The first encapsulating layer can block light, and the second encapsulating layer can allow the light emitted by the lamp beads to pass through.

[0009] As one embodiment, the step of forming the first encapsulating adhesive layer and the second encapsulating adhesive layer on the lamp board includes...

[0010] First, press the first encapsulating adhesive layer onto the lamp plate, and then press the second encapsulating adhesive layer onto the first encapsulating adhesive layer.

[0011] In one embodiment, the step of first forming the first encapsulating adhesive layer on the lamp plate includes...

[0012] The first adhesive film is heated until the first encapsulating adhesive layer therein softens, wherein the first adhesive film includes the first encapsulating adhesive layer and a buffer adhesive layer formed on the first encapsulating adhesive layer, and the adhesion force between the buffer adhesive layer and the first encapsulating adhesive layer is less than a preset force value.

[0013] The first encapsulating adhesive layer of the first adhesive film is oriented toward the lamp bead, and the buffer adhesive layer is pressed down until the first adhesive film is pressed down until the first encapsulating adhesive layer fills the gap space and avoids the top surface of the lamp bead;

[0014] Curing the first encapsulating adhesive layer;

[0015] Remove the buffer adhesive layer.

[0016] In one embodiment, the thickness of the buffer adhesive layer is 2-3 times the thickness of the first encapsulating adhesive layer, and the Shore A hardness of the buffer adhesive layer is less than 60HA.

[0017] In one embodiment, the step of forming the second encapsulating adhesive layer on the first encapsulating adhesive layer includes,

[0018] The second adhesive film is heated until the second encapsulating adhesive layer therein softens. The second adhesive film includes a second encapsulating adhesive layer and a first release film layer that are stacked together.

[0019] The second encapsulating adhesive layer of the second adhesive film is oriented toward the lamp bead, and the first release film layer is pressed down until the second adhesive film is pressed down to the point where the second encapsulating adhesive layer is bonded to the upper surface of the first encapsulating adhesive layer and the top surface of the lamp bead;

[0020] Curing the second encapsulating adhesive layer;

[0021] Remove the first release film layer.

[0022] As one embodiment, the step of forming the first encapsulating adhesive layer and the second encapsulating adhesive layer on the lamp board includes...

[0023] The first and second encapsulating adhesive layers, which are stacked together, are pressed down onto the lamp plate.

[0024] In one embodiment, pressing the first encapsulating adhesive layer and the second encapsulating adhesive layer, which are stacked together, onto the lamp board includes pressing a third adhesive film onto the lamp board. The third adhesive film includes the first encapsulating adhesive layer, the second encapsulating adhesive layer, and a second release film layer, which are stacked together. The thickness of the first encapsulating adhesive layer is greater than or equal to 10 μm, and the total thickness of the first encapsulating adhesive layer and the second encapsulating adhesive layer is 1.2-1.5 times the gap between the lamp bead and the substrate of the lamp board.

[0025] In one embodiment, the material of the first encapsulating adhesive layer is the same as the material of the second encapsulating adhesive layer.

[0026] In one embodiment, pressing the third adhesive film onto the lamp board includes heating the third adhesive film until the first encapsulating adhesive layer softens, and the degree of softening of the first encapsulating adhesive layer is greater than that of the second encapsulating adhesive layer; then, the first encapsulating adhesive layer of the third adhesive film faces the lamp bead, and the second release film layer is pressed down until the third adhesive film is pressed down until the first encapsulating adhesive layer fills the gap, and the thickness of the first encapsulating adhesive layer above the top surface of the lamp bead is less than 10 μm; then, the third adhesive film is cured; and finally, the second release film layer is removed.

[0027] In one embodiment, heating the third adhesive film to soften the first encapsulating adhesive layer includes heating the lamp board, and after the lamp board surface reaches a preset temperature, pressing the third adhesive film down onto the first encapsulating adhesive layer to adhere to the lamp bead, until the first encapsulating adhesive layer softens by absorbing the heat of the lamp bead, and the degree of softening of the first encapsulating adhesive layer is greater than the degree of softening of the second encapsulating adhesive layer.

[0028] The technical advantages of this invention compared to existing technologies are as follows: The LED display encapsulation method uses a first encapsulating adhesive layer that is heated and then pressed down to cover the solder resist ink and fill the gaps between the LED chips. This eliminates the need for underfilling and molding processes, reducing process difficulty and manufacturing costs. Furthermore, since the gaps are filled by the entire first encapsulating adhesive layer under pressure, material consistency is good, resulting in more stable black background effects across batches. The first encapsulating adhesive layer can also cover at least a portion of the sides of the LED chips, further improving the consistency of the black background effect. The top surface of the LED chips may not be covered by the first encapsulating adhesive layer, or the thickness of the first encapsulating adhesive layer on the top surface of the LED chips may be less than 10µm, improving the light output efficiency of the LED display and reducing its power consumption. Additionally, since the molding process is eliminated, the second encapsulating adhesive layer only needs to cover the LED chips, thus reducing the thickness of the LED display and effectively preventing the generation of bright and dark lines during splicing. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a cross-sectional view of the lamp panel provided in an embodiment of the present invention;

[0031] Figure 2 This is a cross-sectional view of an LED display screen packaged using the LED display screen packaging method provided in the embodiments of the present invention.

[0032] Figure 3 This is a cross-sectional view of the first adhesive film provided in an embodiment of the present invention;

[0033] Figure 4 This is a schematic diagram of the preparation stage when the first adhesive film is pressed onto the lamp board according to an embodiment of the present invention;

[0034] Figure 5 This is a cross-sectional view of the second adhesive film provided in an embodiment of the present invention;

[0035] Figure 6 This is a schematic diagram of the preparation stage when the second adhesive film is pressed onto the initial encapsulation lamp board according to an embodiment of the present invention;

[0036] Figure 7 This is a cross-sectional view of the third adhesive film provided in an embodiment of the present invention;

[0037] Figure 8 This is a schematic diagram of the preparation stage when the third adhesive film is pressed onto the lamp board according to an embodiment of the present invention;

[0038] Figure 9 Is adopted Figure 7 A cross-sectional view of an LED display screen encapsulated with a third film.

[0039] Figure 10 This is a flowchart illustrating the LED packaging method provided in Embodiment 1 of the present invention;

[0040] Figure 11 This is a flowchart of the LED packaging method provided in Embodiment 2 of the present invention.

[0041] Explanation of reference numerals in the attached figures:

[0042] 10. Lamp board; 11. Substrate; 1101. First board surface; 1102. Second board surface; 12. Lamp bead; 121. Top surface; 122. Side surface; 13. Solder resist ink; 14. Driver chip; 101. Gap space; 20. Encapsulation layer; 21. First encapsulating adhesive layer; 22. Second encapsulating adhesive layer; 30. First adhesive film; 31. Buffer adhesive layer; 32. First light release film layer; 40. Second adhesive film; 41. First heavy release film layer; 42. Second light release film layer; 50. Third adhesive film; 51. Second heavy release film layer; 52. Third light release film layer; Detailed Implementation

[0043] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0044] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0045] Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," or "third" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0046] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0047] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0048] In recent years, Micro LED displays using COB and MIP packaging technologies have emerged in the industry. The LED chips in Micro LED displays are chip-level LED pixel particles. In terms of manufacturing process, Micro LED displays first bond multiple chip-level LED pixel particles onto a PCB, and then directly package the entire LED board.

[0049] Please see Figure 1The lamp board 10 includes a substrate 11, LED beads 12, a driver chip 14, and solder resist ink 13. The substrate 11 is generally a PCB, and has a first surface 1101 and a second surface 1102 facing each other. The LED beads 12 are multiple LED beads 12, which are disposed on the first surface 1101 of the substrate 11 and electrically connected to the substrate 11. The multiple LED beads 12 are arranged in an array and spaced apart. The LED beads 12 are cubic or cuboid in shape, and have a bottom surface, a top surface 121, and side surfaces 122. The bottom surface and the top surface 121 face each other. There are four side surfaces 122, which surround the top surface 121 and the bottom surface. The bottom surface is soldered to the first surface 1101 of the substrate 11. The top surface 121 and the four side surfaces 122 can emit light, that is, the LED bead 12 has five-sided light emission characteristics. Multiple driver chips 14 are also provided, and multiple driver chips 14 are disposed on the second plate surface 1102 of the substrate 11 and electrically connected to the substrate 11. The driver chips 14 are used to control the light emission of the lamp beads 12. The area on the first plate surface 1101 of the substrate 11 where no lamp beads 12 are disposed forms an interval area. The multiple lamp beads 12 form a gap space 101 above the substrate 11. That is, the projection of the gap space 101 on the first plate surface 1101 coincides with the interval area. The interval area is grid-shaped. Solder resist ink 13 is disposed on the interval area on the first plate surface 1101 of the substrate 11. Solder resist ink 13 is used to protect and isolate the circuit on the substrate 11 and to unify the color of the interval area. After the lamp board 10 is encapsulated, an LED display screen can be obtained. The encapsulation method is generally molding encapsulation. Compression molding refers to the process of injecting or placing liquid or semi-solid epoxy resin or other encapsulation materials into a mold. The encapsulation material fills the gap space 101 and covers the LED bead 12. After the encapsulation material is cured, it forms a hard and transparent or semi-transparent shell on the surface of the lamp board 10 to encapsulate the LED bead 12 and the solder resist ink 13 on the first plate surface 1101 of the substrate 11.

[0050] Compared to traditional SMD (Surface Mount Device) LED displays that do not require encapsulation, MicroLED displays have a shorter manufacturing chain and are easier to achieve ultra-small pitch. However, new technical challenges also arise. MicroLED displays require molding for encapsulation. Besides the complexity and high cost of the molding process, due to the small size of the LED pixels in MicroLED displays, most of the area on the first surface 1101 of the substrate 11 is covered with solder resist ink 13. However, there are color differences in the solder resist ink 13 on each LED board 10, leading to a serious problem of inconsistent background color in MicroLED displays.

[0051] Currently, the industry commonly uses inkjet printing on the bottom of the substrate 11 followed by molding, or molding on the lamp board 10 first and then applying a low-transmittance optical film to the molded surface to cover the color difference between boards. The inkjet printing method on the bottom of the substrate 11 has good coverage of the solder resist ink 13 color, but the process is complex and costly. At the same time, since each lamp board 10 is inkjet printed separately, there are still some differences in the base color between batches, resulting in little improvement in the consistency between batches of LED displays. Although applying a low-transmittance optical film can also alleviate the problem of differences between solder resist inks 13 to some extent, it will reduce the light output efficiency of the lamp board 10 and significantly increase the power consumption of the Micro LED display. In addition, in order to ensure good flow of the encapsulation material on the lamp board 10 during molding, more encapsulation material is filled, resulting in a larger encapsulation layer thickness of the Micro LED display, which is generally above 200um. This leads to severe light emission from the side of the encapsulation layer of the LED display, producing bright and dark lines at the splicing.

[0052] To address the aforementioned issues, this invention provides an LED display packaging method that aims to improve the consistency of the background color effect of the LED display while reducing the complexity and cost of the process, without affecting the light output efficiency of the lamp board 10, and reducing the packaging thickness of the LED display.

[0053] In this embodiment, the LED display packaging method includes:

[0054] The first encapsulating adhesive layer 21 and the second encapsulating adhesive layer 22 are formed on the lamp panel 10, such as Figure 2 The first encapsulating adhesive layer 21 is formed on the lamp panel 10 by heating it to soften and then pressing it into the space between the multiple lamp beads 12. The thickness of the first encapsulating adhesive layer 21 located above the lamp beads 12 is 0-10 μm. The second encapsulating adhesive layer 22 is located on the side of the first encapsulating adhesive layer 21 facing away from the lamp panel 10 and covers the lamp beads 12.

[0055] Understandably, with the first surface 1101 of the substrate 11 facing upwards, the LED bead 12 is positioned above the substrate 11. After being heated to soften, the first encapsulating adhesive layer 21 is prone to plastic deformation. The first encapsulating adhesive layer 21 presses down towards the lamp panel 10, first contacting the LED bead 12 during the pressing process. Then, under the downward pressure, the portion of the first encapsulating adhesive layer 21 corresponding to the area above the lamp panel 10 continuously thins or is punctured, while the portion corresponding to the interstitial area continuously fills the gap space 101 downwards until there is no gap between the first encapsulating adhesive layer 21 and the lamp panel 10. That is, the first encapsulating adhesive layer 21 covers the solder resist ink 13 on the substrate 11 and other interstitial areas except for the solder resist ink 13. The first encapsulating adhesive layer 21 also covers at least a portion of the side surface 122 of the LED bead 12. The first encapsulating adhesive layer above the top surface 121 of the LED bead 12... The thickness of layer 21 is 0-10µm. When the thickness of the first encapsulating adhesive layer 21 above the top surface 121 of the LED bead 12 is 0µm, there is no first encapsulating adhesive layer 21 above the top surface 121 of the LED bead 12. The maximum height of the first encapsulating adhesive layer 21 corresponding to the gap space is less than or equal to the height of the upper surface of the LED bead 12. The first encapsulating adhesive layer 21 forms a grid structure. When there is a first encapsulating adhesive layer 21 above the top surface 121 of the LED bead 12, the first encapsulating adhesive layer 21 in the gap space 101 covers the entire side surface 122 of the LED bead 12. The first encapsulating adhesive layer 21 in the corresponding gap area is connected to the first encapsulating adhesive layer 21 of the corresponding LED bead 12. The maximum height of the first encapsulating adhesive layer 21 corresponding to the gap space is the height of the upper surface of the first encapsulating adhesive layer 21 above the top surface 121 of the LED bead 12. When there is no gap between the first encapsulating adhesive layer 21 and the lamp board 10, it can be said that the first encapsulating adhesive layer 21 fills the gap space 101. At this time, the first encapsulating adhesive layer 21 may not completely fill the gap space 101. The encapsulated LED display screen includes a lamp board 10 and a colloidal structure for encapsulating the lamp board 10. The colloidal structure includes a first encapsulating adhesive layer 21 filling the gap space 101 and a second encapsulating adhesive layer 22 covering the first encapsulating adhesive layer 21 and the lamp board 10.

[0056] The first encapsulating adhesive layer 21 can block light. The first encapsulating adhesive layer 21 can be made of a material that is heat-meltable or whose hardness decreases after being heated. This material can be cured by thermosetting, UV (Ultraviolet) curing, or cooling curing. To achieve the light-blocking requirement, the transmittance of the first encapsulating adhesive layer 21 must be less than or equal to 20%, and the OD (Optical Density) value must be greater than or equal to 2.

[0057] Optionally, the first encapsulating adhesive layer 21 may be made of a modified material that has the characteristics of hot melting at around 80-100℃ or decreasing hardness upon heating and curing between 100-150℃, such as one or more of silicone resin, epoxy resin, acrylic resin, and polyurethane with a refractive index of around 1.5. This material itself may be colorless and transparent; the overall transmittance of the material is adjusted by adding colorants and controlling the proportion of colorants. In this embodiment, the colorant is a black colorant. The Shore D hardness of the cured first encapsulating adhesive layer 21 is greater than 50 HD.

[0058] The second encapsulating adhesive layer 22 allows light emitted by the lamp bead 12 to pass through. The second encapsulating adhesive layer 22 can be made of a high light transmittance material that can be heat-melted or whose hardness decreases after being heated. This material can be cured by heat curing, UV curing or cooling curing.

[0059] Optionally, the second encapsulating layer 22 can be made of one or more of the following: colorless and transparent silicone resin, epoxy resin, acrylic resin, and polyurethane with a refractive index of around 1.5. The second encapsulating layer 22 can be made solely of the colorless and transparent material itself, without the addition of colorants, and its transmittance is greater than or equal to 90%. To improve the uniformity and softness of the light emitted by the LED display, the second encapsulating layer 22 may contain diffusing particles, the proportion of which can be selected as 2-10%.

[0060] The LED display encapsulation method involves heating and pressing a low-transmittance encapsulating layer 21 to cover the solder resist ink 13 and fill the gaps 101 between the LED chips 12. This eliminates the need for underfilling and molding processes, reducing manufacturing complexity and costs. Furthermore, since the first encapsulating layer 21 on each LED panel 10 can be divided from a single roll of encapsulating layer, the consistency of the encapsulation material across the entire LED display is excellent, resulting in more stable black background effects across batches. The first encapsulating layer 21 can also cover at least a portion of the side surface 122 of the LED chips 12, further improving the consistency of the black background effect. The top surface 121 of the LED chips 12 may not be covered by the first encapsulating layer 21, or the thickness of the first encapsulating layer 21 on the top surface 121 of the LED chips 12 may be less than 10µm, improving the light extraction efficiency and reducing the power consumption of the LED display. Meanwhile, since the molding process is eliminated, the second encapsulation layer 22 only needs to cover the LED beads 12, without any thickness limit. Therefore, the encapsulation thickness of the LED display screen is reduced, and the light emission of the lamp board 10 on the side of its encapsulation layer 20 is reduced, thereby effectively preventing the generation of bright and dark lines at the splicing.

[0061] It should be noted that the thickness of the first encapsulating adhesive layer 21 can be set to be greater than the gap between the LED bead 12 and the substrate 11. Since the gap space 101 is a circumferentially open space, the first encapsulating adhesive layer 21 can overflow from the edge of the LED bead 12 during the pressing process until the thickness of the first encapsulating adhesive layer 21 on the lamp board 10 meets the requirement of filling the gap space 101 and having a thickness of less than 10 μm above the LED bead 12. The first encapsulating adhesive layer 21 can be pressed down using a hot press to achieve heating and pressing of the first encapsulating adhesive layer 21. To avoid residual air between the first encapsulating adhesive layer 21 and the lamp board 10, the encapsulation process of the lamp board 10 needs to be carried out in a vacuum environment. Optionally, the hot press is a vacuum hot press, and the lamp board 10 is placed inside the vacuum hot press to ensure that the encapsulation process is carried out in a vacuum environment.

[0062] Optional, such as Figure 2 The first encapsulating adhesive layer 21 in the gap space 101 can cover the entire side 122 of the lamp bead 12, so as to effectively block the light emitted from the side 122 of the lamp bead 12, making the light emission angle of each lamp bead 12 of the LED display panel more consistent, thereby improving the display effect of the LED display screen.

[0063] Optionally, the upper surface of the second encapsulating layer 22 is a smooth surface, or it is provided with an AG (Anti-glare) structure to improve the anti-glare effect of the LED display.

[0064] In this encapsulation method, the first encapsulating adhesive layer 21 is first pressed down onto the lamp board 10 to encapsulate the lamp board 10 as a preliminary encapsulated lamp board 10. Then, the second encapsulating adhesive layer 22 is pressed down onto the first encapsulating adhesive layer 21 of the preliminary encapsulated lamp board 10 to complete the encapsulation of the lamp board 10. This method allows the first encapsulating adhesive layer 21 and the second encapsulating adhesive layer 22 to be set independently. The heating temperatures of the first encapsulating adhesive layer 21 and the second encapsulating adhesive layer 22 do not affect each other. The thickness of the first encapsulating adhesive layer 21 only needs to be sufficient to fill the gap space 101 after pressing down without affecting the light emission from the top surface 121 of the first encapsulating adhesive layer 21. The thickness of the second encapsulating adhesive layer 22 only needs to be sufficient to cover the top surface 121 of the lamp board 10, fill the gap between the first encapsulating adhesive layer 21 and the lamp board 10, and ensure that the upper surface of the second encapsulating adhesive layer 22 is flat. Optionally, after being pressed down, the first encapsulating adhesive layer 21 may only cover the solder resist ink 13 and at least part of the side surface 122 of the lamp board 10, while avoiding the top surface 121 of the lamp board 10, so as to improve the consistency of the background color effect and improve the light output efficiency.

[0065] Of course, after pressing down the first encapsulating adhesive layer 21, a certain thickness of the first encapsulating adhesive layer 21 can also be left on the top surface 121 of the lamp board 10. The thickness of the first encapsulating adhesive layer 21 on the top surface 121 of the lamp board 10 does not affect the light output efficiency, and there is no restriction here.

[0066] In this encapsulation method, the first encapsulating layer 21 and the second encapsulating layer 22 can be stacked to form an encapsulation layer 20, and then the encapsulation layer 20 can be pressed down onto the lamp panel 10. In this way, the first encapsulating layer 21 and the second encapsulating layer 22 form a whole before being pressed down onto the lamp panel 10, namely the encapsulation layer 20. During operation, only the encapsulation layer 20 needs to be pressed down to complete the simultaneous encapsulation of the lamp panel 10 by the first encapsulating layer 21 and the second encapsulating layer 22. This encapsulation method only requires one pressing step, which is simple to operate and improves the encapsulation efficiency. In particular, after the pressing operation, the thickness of the first encapsulating layer 21 on the top surface 121 of the lamp panel 10 only needs to have little impact on the light emission efficiency and the upper surface of the second encapsulating layer 22 needs to be flat.

[0067] The following two examples illustrate this.

[0068] Example 1

[0069] Please see Figure 3 and Figure 4 First, prepare a first adhesive film 30 and a second adhesive film 40. The first adhesive film 30 includes a buffer adhesive layer 31, a first encapsulating adhesive layer 21 and a first light release film layer 32 stacked together. The second adhesive film 40 includes a first heavy release film layer 41, a second encapsulating adhesive layer 22 and a second light release film layer 42 stacked together.

[0070] For the first adhesive film 30, the buffer adhesive layer 31 and the first light release film layer 32 are used to protect the two sides 122 of the first encapsulating adhesive layer 21, respectively. The adhesion force between the buffer adhesive layer 31 and the first encapsulating adhesive layer 21 is less than a preset force value to facilitate the separation of the buffer adhesive layer 31 and the first encapsulating adhesive layer 21. Optionally, the preset force value is 100 kgf.

[0071] The adhesion between the first light release film layer 32 and the first encapsulating adhesive layer 21 is less than the adhesion between the buffer adhesive layer 31 and the first encapsulating adhesive layer 21. When the first light release film layer 32 is pulled, it separates from the first encapsulating adhesive layer 21 before the buffer adhesive layer 31. For example, a release agent is applied between the buffer adhesive layer 31 and the first encapsulating adhesive layer 21, or another release film layer is provided.

[0072] For the second adhesive film 40, the first heavy release film layer 41 and the second light release film layer 42 are used to protect the two sides 122 of the second encapsulating adhesive layer 22, respectively. The adhesion between the second light release film layer 42 and the second encapsulating adhesive layer 22 is less than the adhesion between the first heavy release film layer 41 and the second encapsulating adhesive layer 22. When the second light release film layer 42 is pulled, the light release film layer separates from the second encapsulating adhesive layer 22 before the first heavy release film layer 41.

[0073] The first heavy release film layer 41, the first light release film layer 32, and the second light release film layer 42 are all films with release properties, which can easily separate from adhesives or other materials under certain conditions without leaving any residue or only a very slight stickiness. In this embodiment, the release film can be a polyester film such as PET or TAC.

[0074] Please see Figure 5 The packaging methods for LED displays include:

[0075] S1. Remove the first light release film layer 32 of the first adhesive film 30: Place the first adhesive film 30 under the pressure head of the vacuum hot press, with the pressure head connected to the buffer adhesive layer 31, and remove the first light release film layer 32, as follows. Figure 6 At this time, the first adhesive film 30 only has a buffer adhesive layer 31 that connects to the pressure head and a first encapsulating adhesive layer 21 facing the lamp board 10;

[0076] S2. Heat the first adhesive film 30 until the first encapsulating adhesive layer 21 therein softens: Heat the first adhesive film 30 using a vacuum hot press until the first encapsulating adhesive layer 21 softens;

[0077] S3. Orient the first encapsulating adhesive layer 21 of the first adhesive film 30 toward the lamp bead 12, as shown. Figure 6 The first adhesive film 30 is pressed down by the pressure head of the vacuum hot press until the first encapsulating adhesive layer 21 fills the gap space 101, avoiding the top surface 121 of the lamp bead 12. The first adhesive film 30 is pressed down by the pressure head of the vacuum hot press, and the first encapsulating adhesive layer 21 of the first adhesive film 30 presses against the top surface 121 of the lamp bead 12. Because the adhesion between the first encapsulating adhesive layer 21 and the buffer adhesive layer 31 is less than the preset force value, the lamp bead 12 can puncture the first encapsulating adhesive layer 21 during the pressing process. The first encapsulating adhesive layer 21 gathers towards the gap space 101. The pressure head continues to press down, and the first encapsulating adhesive layer 21 sinks under the pressure of the buffer adhesive layer 31. The first encapsulation layer 21 fills the gap space 101 and completely avoids the top surface 121 of the lamp bead 12 until the lower surface of the buffer adhesive layer 31 is in close contact with the top surface 121 of the lamp bead 12 and the first encapsulation adhesive layer 21 is in full contact with the solder resist ink 13 and the side surface 122 of the lamp bead 12. There are no unfilled dead corners at the top corner of the gap space 101, and the thickness of the first encapsulation adhesive layer 21 meets the preset requirements. The maximum height of the first encapsulation adhesive layer 21 in the gap space 101 is less than or equal to the height of the top surface 121 of the lamp bead 12. Optionally, the thickness of the lowest point of the first encapsulation adhesive layer 21 in the gap space 101 is 0.8-1 times the gap difference between the lamp bead 12 and the substrate 11.

[0078] S4. Curing the first adhesive film 30: The Shore D hardness of the first encapsulating adhesive layer 21 after curing is less than 50HD;

[0079] S5. Remove the buffer adhesive layer 31 to form the preliminary encapsulated lamp board 10, as shown. Figure 7 ;

[0080] S6. Remove the second light release film layer 42 of the second adhesive film 40: Place the second adhesive film 40 on the pressure head of the vacuum hot press, such that the pressure head is connected to the first heavy release film layer 41, and remove the second light release film layer 42, as follows. Figure 7 At this time, the second adhesive film 40 only has the first release film layer 41 connecting the pressure head and the second encapsulating adhesive layer 22;

[0081] S7. Heat the second adhesive film 40 until the second encapsulating adhesive layer 22 therein softens: Heat the second adhesive film 40 using a vacuum hot press until the second encapsulating adhesive layer 22 softens;

[0082] S8. Orient the second encapsulating adhesive layer 22 of the second adhesive film 40 toward the LED bead 12, as shown. Figure 7 The first release film layer 41 is pressed down until the second adhesive film 40 is pressed down to adhere to the second encapsulation adhesive layer 22 and the upper surface of the first encapsulation adhesive layer 21 and the top surface 121 of the lamp bead 12: the second adhesive film 40 is pressed down by the pressure head of the vacuum hot press, and the second encapsulation adhesive layer 22 of the second adhesive film 40 adheres to the top surface 121 of the lamp bead 12. The second adhesive film 40 is pressed down until the second encapsulation adhesive layer 22 adheres to the top surface 121 of the first encapsulation adhesive layer 21. At this time, the second encapsulation adhesive layer 22 partially fills the gap space 101 corresponding to the gap space 101, and the thickness of the second encapsulation adhesive layer 22 above the top surface 121 of the lamp board 10 reaches the preset requirement. The pressure head can flatten the upper surface of the second encapsulation adhesive layer 22 through the first release film layer 41.

[0083] S9, Curing the second adhesive film 40;

[0084] S10. Remove the first release film layer 41 to complete the encapsulation. Figure 2 .

[0085] Optionally, the buffer adhesive layer 31 is made of a high-temperature resistant elastic material, so that when the first adhesive film 30 is pressed, the buffer adhesive layer 31 can continuously apply pressure to the softened first encapsulating adhesive layer 21 through its own elasticity, thereby allowing the first encapsulating adhesive layer 21 to fully fill the corner areas of the gap space 101, while also achieving a thinning of the first encapsulating adhesive layer 21. When the first encapsulating adhesive layer 21 is relatively thin, the lowest point of the first encapsulating adhesive layer 21 in the gap space 101 is pressed down to below the top surface 121 of the lamp bead 12, ensuring that the first encapsulating adhesive layer 21 is in full contact with the solder resist ink 13 and the side surface 122 of the lamp bead 12, avoiding the formation of unfilled dead corners. After the first adhesive film 30 is pressed down to adhere to the top surface 121 of the LED bead 12 by the buffer adhesive layer 31, the first adhesive film 30 can be pressed down further. The portion of the buffer adhesive layer 31 corresponding to the top surface 121 of the LED bead 12 is compressed, while the portion corresponding to the gap space 101 protrudes towards the gap space 101 through its own elastic deformation. This causes the upper surface of the first encapsulating adhesive layer 21 within the gap space 101 to form a concave arc surface under the pressure of the buffer adhesive layer 31. Optionally, since the surface elastic deformation of the buffer adhesive layer 31 at the gap space 101 is a convex arc surface, the edge of the first encapsulating adhesive layer 21 within the gap space 101 can be flush with the top surface of the LED bead 12, thus covering the entire side surface of the LED bead 12.

[0086] Furthermore, the Shore A hardness of the buffer adhesive layer 31 is less than 60HA, so that it can continuously press down on the first encapsulating adhesive layer 21 within the gap space 101 through greater elastic deformation. The buffer adhesive layer 31 can be made of silicone, rubber, etc. To ensure the supporting force and downward pressure of the buffer adhesive layer 31 on the first encapsulating adhesive layer 21, the thickness of the buffer adhesive layer 31 is 2-3 times that of the first encapsulating adhesive layer 21 to improve its stiffness. Of course, the buffer adhesive layer 31 can also be an adhesive layer with higher hardness. After the first adhesive film 30 is pressed down until the first encapsulating adhesive layer 21 fills the gap space 101, the upper surface of the first encapsulating adhesive layer 21 in the gap space 101 can be flat and flush with the top surface 121 of the LED bead 12; no restrictions are placed here.

[0087] Optionally, the first encapsulating adhesive layer 21 within the gap space 101 may cover the side 122 of the LED bead 12 to improve the consistency of the background color effect of the LED display screen. Of course, in other embodiments, the first encapsulating adhesive layer 21 may only cover the lower half of the side 122 of the LED bead 12, which can be set according to the light emission requirements and is not limited here.

[0088] Example 2

[0089] First, prepare the third adhesive film 50, such as Figure 8The third adhesive film 50 includes a second heavy release film layer 51, a second encapsulating adhesive layer 22, a first encapsulating adhesive layer 21, and a third light release film layer 52, all stacked together. The first encapsulating adhesive layer 21 and the second encapsulating adhesive layer 22 together form the aforementioned encapsulation layer 20. The first heavy release film layer 41 protects the second encapsulating adhesive layer 22, and the third light release film layer 52 protects the first encapsulating adhesive layer 21. The adhesion between the first encapsulating adhesive layer 21 and the second encapsulating adhesive layer 22 is greater than the adhesion between the second heavy release film layer 51 and the second encapsulating adhesive layer 22, which in turn is greater than the adhesion between the third light release film layer 52 and the first encapsulating adhesive layer 21. When the third light release film layer 52 is pulled, the third light release film layer 52 separates from the first encapsulating adhesive layer 21 before the second heavy release film layer 51 separates from the second encapsulating adhesive layer 22.

[0090] The thickness of the first encapsulating adhesive layer 21 is greater than or equal to 10 μm, and the total thickness of the first encapsulating adhesive layer 21 and the second encapsulating adhesive layer 22 is 1.2-1.5 times the thickness of the lamp bead 12, so as to ensure that the first encapsulating adhesive layer 21 covers the solder resist ink 13 and the first encapsulating adhesive layer 21 and the second encapsulating adhesive layer 22 together achieve the encapsulation of the lamp board 10.

[0091] Please see Figure 9 The packaging methods for LED displays include:

[0092] P1. Remove the third light release film layer 52 of the third adhesive film 50: Place the third adhesive film 50 under the pressure head of the vacuum hot press, with the pressure head connected to the second heavy release film layer 51, and remove the third light release film layer 52, as follows. Figure 10 At this time, the third adhesive film 50 only has the second release film layer 51, the second encapsulating adhesive layer 22 and the first encapsulating adhesive layer 21;

[0093] P2. Heating the third adhesive film 50 until the first encapsulating adhesive layer 21 softens, with the softening degree of the first encapsulating adhesive layer 21 being greater than that of the second encapsulating adhesive layer 22: The lamp board 10 is heated using a vacuum hot press. After the surface of the lamp board 10 reaches a preset temperature, the third adhesive film 50 is pressed down onto the first encapsulating adhesive layer 21 and adhered to the lamp bead 12 using a pressure head. In this way, the heat from the lamp bead 12 heats the third adhesive film 50 from bottom to top. The third adhesive film 50 absorbs the heat from the lamp bead 12, and the first encapsulating adhesive layer 21 in contact with the lamp bead 12 receives more heat. The second encapsulating layer 22, which is not in contact with the LED bead 12, is less heated. When the first encapsulating layer 21 softens by absorbing the heat of the LED bead 12, the part of the second encapsulating layer 22 that is close to the first encapsulating layer 21 can be softened by heat, while the part that is far away from the first encapsulating layer 21 can maintain a certain hardness. This makes the softening degree of the first encapsulating layer 21 greater than that of the second encapsulating layer 22, so that the second encapsulating layer 22 can provide sufficient support for the first encapsulating layer 21 and ensure that the upper surface of the second encapsulating layer 22 is flat.

[0094] P3. Position the first encapsulating adhesive layer 21 of the third adhesive film 50 towards the LED bead 12, and press down the second release film layer 51 until the third adhesive film 50 is pressed down until the first encapsulating adhesive layer 21 fills the gap, and the thickness of the first encapsulating adhesive layer 21 above the top surface 121 of the LED bead 12 is less than 10µm. Continue pressing down the third adhesive film 50 using the pressure head of the vacuum hot press. Due to softening and increased fluidity, the first encapsulating adhesive layer 21 can plastically deform under the pressure of the second encapsulating adhesive layer 22. The portion of the first encapsulating adhesive layer 21 corresponding to the top surface 121 of the LED bead 12 becomes thinner, and the portion of the first encapsulating adhesive layer 21 corresponding to the gap space 101 continues to flow downwards until it fills the gap space 101. Because the first... The adhesion between the first encapsulating layer 21 and the second encapsulating layer 22 is relatively strong, so the first encapsulating layer 21 and the second encapsulating layer 22 remain adhered. The first encapsulating layer 21 cannot be punctured, and the first encapsulating layer 21 above the top surface 121 of the LED bead 12 will only thin and will not disappear. When the first encapsulating layer 21 fills the gap space 101 and the thickness of the first encapsulating layer 21 above the top surface 121 of the LED bead 12 is 5-10 μm, the pressing action can be stopped. At this time, since the part of the second encapsulating layer 22 near the first encapsulating layer 21 also has a certain degree of fluidity, the upper surface of the first encapsulating layer 21 in the gap space 101 can be a concave arc surface in the middle. Figure 11 Optionally, the thickness of the lowest point of the first encapsulating adhesive layer 21 within the gap space 101 is 0.5-1 times the discontinuity between the lamp bead 12 and the substrate 11. The first encapsulating adhesive layer 21 with a thickness of 5-10 μm above the top surface 121 of the lamp bead 12 has little impact on the light emission efficiency of the lamp bead 12. In particular, since the second encapsulating adhesive layer 22 is heated much less than the first encapsulating adhesive layer 21, its fluidity is small, thus avoiding the fusion phenomenon between the first encapsulating adhesive layer 21 and the second encapsulating adhesive layer 22 and ensuring the encapsulation effect of the lamp board 10.

[0095] P4. Curing the third adhesive film 50: Curing the first encapsulating adhesive layer 21 and the second encapsulating adhesive layer 22. The Shore D hardness of the first encapsulating adhesive layer 21 after curing is less than 50HD.

[0096] P5. Remove the third light release film layer 52 to complete the encapsulation. Figure 11 .

[0097] It should be noted that when heating the first encapsulating adhesive layer 21, the second encapsulating adhesive layer 22 needs to be heated less in order to maintain a certain hardness to provide downward support for the first encapsulating adhesive layer 21.

[0098] In this embodiment, since the top surface 121 of the LED bead 12 also has a first encapsulating adhesive layer 21, it can be ensured that the first encapsulating adhesive layer 21 covers the side surface 122 of the LED bead 12, thereby reducing the impact of light emitted from the side surface 122 of the LED bead 12 on the consistency of the background color effect. At the same time, since the first encapsulating adhesive layer 21 on the top surface 121 of the lamp board 10 is relatively thin, it can be ensured that the light transmittance of the encapsulated LED display screen is greater than or equal to 80%.

[0099] Optionally, the first encapsulating adhesive layer 21 and the second encapsulating adhesive layer 22 can be made of the same material to facilitate processing, improve the adhesion between the two, and maintain the same or similar coefficient of thermal expansion.

[0100] Optionally, since the third adhesive film 50 requires the second release film to provide support during the pressing process, the second release film layer 51 needs to have a certain stiffness. In this embodiment, the thickness of the second release film is 150-200um to ensure that it provides sufficient support to the second adhesive film 40.

[0101] The above descriptions are merely several specific embodiments of the present invention, and only specifically describe the technical principles of the present invention. These descriptions are only for explaining the principles of the present invention and should not be construed as limiting the scope of protection of the present invention in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention, as well as other specific embodiments of the present invention that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of the present invention.

Claims

1. A method for packaging an LED display screen, characterized in that, include: A first encapsulating layer and a second encapsulating layer are formed on the lamp board. The first encapsulating layer is formed on the lamp board by heating it to soften and then pressing it into the gap space between a plurality of lamp beads on the lamp board. The thickness of the first encapsulating layer located above the top surface of the lamp beads is 0-10 μm. The second encapsulating layer is located on the side of the first encapsulating layer opposite to the lamp board and covers the lamp beads. The first encapsulating layer can block light, and the second encapsulating layer can allow the light emitted by the lamp beads to pass through. The step of forming the first encapsulating adhesive layer and the second encapsulating adhesive layer on the lamp board includes: First, press the first encapsulating adhesive layer onto the lamp board, and then press the second encapsulating adhesive layer onto the first encapsulating adhesive layer; The step of first forming the first encapsulating adhesive layer on the lamp board includes: The first adhesive film is heated until the first encapsulating adhesive layer therein softens. The first adhesive film includes the first encapsulating adhesive layer and a buffer adhesive layer formed on the first encapsulating adhesive layer. The buffer adhesive layer is an elastic functional layer made of silicone or rubber. The thickness of the buffer adhesive layer is 2-3 times the thickness of the first encapsulating adhesive layer. The Shore A hardness of the buffer adhesive layer is less than 60HA. The adhesion between the buffer adhesive layer and the first encapsulating adhesive layer is less than a preset force value. The preset force value is 100kgf, so that the first encapsulating adhesive layer is punctured during the downward pressing of the buffer adhesive layer. During the downward pressing of the buffer adhesive layer, the portion of the buffer adhesive layer corresponding to the gap space between two adjacent LED beads protrudes towards the gap space through its own elastic deformation, so that the upper surface of the first encapsulating adhesive layer in the gap space forms a concave arc surface in the middle under the pressing of the buffer adhesive layer. The edge of the first encapsulating adhesive layer in the gap space is flush with the top surface of the LED bead, so as to cover the entire side of the LED bead. The first encapsulating adhesive layer of the first adhesive film is oriented toward the lamp bead, and the buffer adhesive layer is pressed down until the first adhesive film is pressed down until the first encapsulating adhesive layer fills the gap space and avoids the top surface of the lamp bead; Curing the first encapsulating adhesive layer; Remove the buffer adhesive layer; or, The step of forming the first encapsulating adhesive layer and the second encapsulating adhesive layer on the lamp board includes: The first encapsulating adhesive layer and the second encapsulating adhesive layer, which are stacked together, are pressed down onto the lamp board. The material of the first encapsulating adhesive layer is the same as that of the second encapsulating adhesive layer. The step of pressing the first encapsulating adhesive layer and the second encapsulating adhesive layer, which are stacked together, onto the lamp board includes pressing a third adhesive film onto the lamp board. The third adhesive film includes the first encapsulating adhesive layer, the second encapsulating adhesive layer, and the second release film layer, which are stacked together. The thickness of the first encapsulating adhesive layer is greater than or equal to 10 μm. The total thickness of the first encapsulating adhesive layer and the second encapsulating adhesive layer is 1.2-1.5 times the difference between the lamp bead and the substrate of the lamp board. The step of pressing the third adhesive film onto the lamp board includes: heating the third adhesive film until the first encapsulating adhesive layer softens, and the degree of softening of the first encapsulating adhesive layer is greater than that of the second encapsulating adhesive layer; then, facing the first encapsulating adhesive layer of the third adhesive film toward the lamp bead, and pressing down the second release film layer until the third adhesive film is pressed down until the first encapsulating adhesive layer fills the gap, and the thickness of the first encapsulating adhesive layer above the top surface of the lamp bead is less than 10 μm; then, curing the third adhesive film; and finally, removing the second release film layer. The step of heating the third adhesive film to soften the first encapsulating adhesive layer includes: heating the lamp board, and after the surface of the lamp board reaches a preset temperature, pressing the third adhesive film down onto the first encapsulating adhesive layer to adhere to the lamp bead, until the first encapsulating adhesive layer softens by absorbing the heat of the lamp bead, and the degree of softening of the first encapsulating adhesive layer is greater than the degree of softening of the second encapsulating adhesive layer, so as to avoid the first encapsulating adhesive layer and the second encapsulating adhesive layer from melting together.

2. The LED display packaging method as described in claim 1, characterized in that, The step of forming the second encapsulating adhesive layer on the first encapsulating adhesive layer includes... The second adhesive film is heated until the second encapsulating adhesive layer therein softens. The second adhesive film includes a second encapsulating adhesive layer and a first release film layer that are stacked together. The second encapsulating adhesive layer of the second adhesive film is oriented toward the lamp bead, and the first release film layer is pressed down until the second adhesive film is pressed down to the point where the second encapsulating adhesive layer is bonded to the upper surface of the first encapsulating adhesive layer and the top surface of the lamp bead; Curing the second encapsulating adhesive layer; Remove the first release film layer.

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