LED display module and preparation method

Abstract

The invention discloses an LED display module and a preparation method thereof. The display module comprises a substrate, electronic components, LED lamp beads, a transition layer and a packaging layer. The LED lamp beads are arranged on the substrate, the LED lamp beads are contained in the packaging layer, the transition layer is arranged between the LED lamp beads and the packaging layer, and the transition layer covers the surfaces of the LED lamp beads; the surface of the packaging layer is a display surface of the display module, the height difference between the highest point and the lowest point of the display surface of the display module is h1, and the value range of h1 meets the condition that h1 is larger than or equal to 0 and smaller than or equal to 0.2 mm. The transition layer is arranged on the outer side of the LED lamp bead, so that the thermal expansion coefficient difference among the substrate, the transition layer and the packaging layer is reduced, and the conditions of warping and bending are effectively reduced.

Description

Technical Field

[0001] This invention relates to the field of LED display module technology, and specifically to an LED display module and its manufacturing method. Background Technology

[0002] Due to the miniaturization of LED chips, current LED display modules utilize COB (Chip-on-Board) packaging to encapsulate the entire display module, improving the reliability of the display module formed from small-pitch LED chips. However, because the coefficient of thermal expansion of the COB encapsulant differs significantly from that of the LED display substrate, the LED display module is prone to warping and bending after encapsulation, affecting its display performance. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides an LED display module and its manufacturing method. By setting a transition layer on the outside of the LED beads, the difference in thermal expansion coefficients between the substrate, the transition layer, and the encapsulation layer is reduced, thereby effectively reducing warping and bending.

[0004] This invention provides an LED display module, which includes: a substrate, electronic components, LED beads, a transition layer, and an encapsulation layer; The LED beads are disposed on the substrate and housed within the encapsulation layer. The transition layer is disposed between the LED beads and the encapsulation layer and covers the surface of the LED beads. The surface of the encapsulation layer is the display surface of the display module. The height difference between the highest and lowest points of the display surface of the display module is h1, and the value range of h1 satisfies: 0≤h1≤0.5mm.

[0005] Furthermore, the surface height difference of the display surface of the display module can be measured using laser three-dimensional scanning. Furthermore, the transition layer is made of a flexible material, and the elastic modulus of the transition layer is K, wherein the value of K is in the range of 0.1 MPa ≤ K ≤ 1 MPa.

[0006] Furthermore, the thickness of the transition layer is h2, and the value of h2 is in the range of 5μm≤h2≤30μm.

[0007] Furthermore, the transition layer is made of one of the following materials: silicone rubber, polyurethane elastomer, modified PDMS, or nanocomposite organosilicon gel.

[0008] Furthermore, the thickness of the transition layer covering the sidewall of the LED bead is h3, and the thickness of the transition layer covering the top surface of the LED bead is h4. The constraint relationship between h3 and h4 is: h3 > h4.

[0009] Furthermore, the thermal expansion coefficient of the encapsulation layer is P1, and the value of P1 ranges from 15ppm / ℃ to 20ppm / ℃.

[0010] Furthermore, the shrinkage rate of the encapsulation layer is 'a', and the value of 'a' ranges from 0.1% to 0.7%.

[0011] Furthermore, the coefficient of thermal expansion of the substrate material is P2, and the value of P2 is in the range of 12ppm / ℃≤P2≤18ppm / ℃.

[0012] Furthermore, the expansion and contraction stress between the transition layer and the substrate satisfies the condition that the interfacial shear stress τ is less than the cohesive strength of the colloid.

[0013] Furthermore, the interfacial shear stress τ satisfies the calculation formula: ; in, Let c be the elastic modulus of the encapsulating adhesive. For the encapsulating adhesive, Poisson's ratio, For CTE difference, Let c be a function of the thickness ratio of the adhesive layer c to the substrate s. ,when When the substrate is a rigid substrate, 0.75≤ ≤1.25.

[0014] The present invention also provides a method for manufacturing an LED display module, the method comprising: Several LED beads are mounted on the substrate and then baked and dried. The substrate that has undergone baking and drying is sandblasted to obtain the initial display board. A transition layer was prepared on the initial substrate of the display screen using an dip-coating method. Encapsulating adhesive is applied to the surface of the transition layer to form a plastic-encapsulated structure; After the plastic encapsulation structure has been cured and shaped, the LED display module is obtained by trimming the encapsulation layer.

[0015] This invention provides an LED display module and its manufacturing method. By covering the surface of several LED beads with a transition layer, the difference in the coefficient of thermal expansion between the substrate material, the transition layer, and the encapsulation layer of the LED display module is reduced, thereby reducing the risk of warping and bending of the encapsulation adhesive of the LED display module and improving the reliability of the LED display module. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments 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.

[0017] Figure 1 This is a schematic diagram of the LED display module in an embodiment of the present invention; Figure 2 This is a flowchart of the LED display module manufacturing method in an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Example 1: Figure 1 A schematic diagram of the structure of an LED display module in an embodiment of the present invention is shown. The display module includes: a substrate 101, electronic components 102, LED beads 103, a transition layer 104, and an encapsulation layer 105. A plurality of LED beads 103 are disposed on the front side of the substrate 101, and the electronic components 102 are disposed on the back side of the substrate 101. The substrate 101 is used to support the electronic components 102 and the LED beads 103. The electronic components 102 include resistors, capacitors, integrated circuit chips, and other devices, which are fixed on the substrate 101 by surface mount technology. Based on the electronic components 102, the light output control of the plurality of LED beads 103 of the display module can be satisfied to achieve the display effect of the display module.

[0020] Furthermore, the encapsulation layer 105 is formed based on encapsulation adhesive covering technology. By covering the entire surface of the LED module in the surface mount process with a layer of special transparent optical adhesive for encapsulation protection, the encapsulation consistency and light emission efficiency of the display module can be improved.

[0021] The LED bead 103 is disposed on the substrate 101 and is housed within the encapsulation layer 105. The transition layer 104 is disposed between the LED bead 103 and the encapsulation layer 105, covering the LED bead 103 and the surface of the substrate 101. The encapsulation layer 105 covers the transition layer 104, preventing the encapsulation layer 105 from directly contacting the surface of the substrate 101. This allows the transition layer 104 to absorb the expansion and contraction stress of the encapsulating adhesive, thereby reducing the risk of warping or cracking of the encapsulation layer 105.

[0022] The transition layer 104 is disposed between the substrate 101 and the encapsulation layer 105, serving as an intermediate material layer between the substrate 101 and the encapsulation layer 105. Specifically, it can be implemented using silicone rubber or polyurethane elastomer. It is formed by dip-coating method to cover the surface of the lamp bead, and is used to absorb the mechanical stress generated by the curing shrinkage of the encapsulation layer 105.

[0023] The surface of the encapsulation layer 105 is the display surface of the display module. The size of the display module is greater than or equal to 300mm. The height difference between the highest and lowest points of the display surface of the display module is h1, and the value range of h1 satisfies: 0≤h1≤0.5mm. That is, the surface of the display module with the completed encapsulation structure can maintain good flatness, so that the encapsulation structure of the LED display module has good encapsulation stability, thereby ensuring the display effect of the LED display module.

[0024] Furthermore, the surface height difference of the display surface of the display module can be measured using laser three-dimensional scanning. By scanning the display surface of the display module with a laser measuring device and detecting the detection distance at various points on the display surface using laser ranging, the overall flatness of the display module's display surface can be obtained. A transition layer 104 is provided to form a gradient transition structure of thermal expansion coefficient between the encapsulation layer 105 and the substrate 101. This transition layer 104 covers the surface of the LED beads 103 and fills the gaps between several LED beads 103. Utilizing its low elastic modulus characteristics, it absorbs the deformation stress caused by the curing shrinkage of the encapsulation adhesive and temperature changes. Simultaneously, by constraining the difference in thermal expansion coefficient between the thickness of the encapsulation layer 105 and the substrate 101, the height difference h1 of the display surface is controlled to be ≤0.2mm, thereby achieving an anti-warping planar encapsulation structure in large-size modules of 300mm or more.

[0025] Specifically, the transition layer 104 is made of a flexible material, and the elastic modulus of the transition layer 104 is K, with the value of K ranging from 0.1 MPa to K to 1 MPa. The transition layer 104 is formed based on a flexible material, which gives it good elastic deformation capability. When the display module is encapsulated, it can absorb the expansion and contraction stress caused by the difference in the thermal expansion coefficients of the materials between the substrate 101 and the encapsulation layer 105, thus meeting the plastic encapsulation protection requirements of the LED display module.

[0026] Furthermore, the transition layer 104 is made of a flexible material, possessing good elasticity and flexibility, capable of accommodating the thermal expansion differences between the encapsulation layer 105 and the substrate 101. The elastic modulus K of the transition layer 104 is controlled within the range of 0.1 MPa to 1 MPa, ensuring that the transition layer 104 possesses sufficient flexibility to absorb stress while maintaining appropriate support to ensure structural stability.

[0027] Specifically, the thickness of the transition layer 104 is h2, and the value of h2 is in the range of 5μm≤h2≤30μm. The value of h2 can be one of 5μm, 10μm, 15μm, 20μm, 25μm, and 30μm, so that the transition layer 104 can meet the requirements for absorbing the material expansion and contraction stress between the substrate 101 and the encapsulation layer 105 of the LED display module, and can meet the requirements for plastic encapsulation protection of the LED beads 103.

[0028] Furthermore, the transition layer 104 can be processed by precision spraying, multiple precision spraying, dip-coating, vacuum hot pressing, etc., to fix several LED beads 103 on the substrate 101. By coating the LED beads 103 and the substrate 101 to form the transition layer 104, the transition layer 104 can cover and protect the LED beads 103 and the substrate 101, and form a transition structure between the substrate 101 and the encapsulation layer 105, so as to absorb the expansion and contraction stress generated by the encapsulation between different materials and reduce the risk of warping and cracking of the LED display module.

[0029] Specifically, the transition layer 104 is made of one of the following materials: silicone rubber, polyurethane elastomer, modified PDMS, or nanocomposite silicone gel. Silicone rubber, in particular, possesses excellent flexibility and resistance to high and low temperatures, allowing it to adapt to the thermal deformation differences between the encapsulation layer 105 and the substrate 101. During the preparation process, liquid silicone rubber is first uniformly coated onto the surface of the LED bead 103 using an dip-coating method to form a thin film. Then, a thermosetting treatment is performed to cross-link the silicone rubber. The cured silicone rubber transition layer 104 forms a flexible buffer interface between the encapsulation layer 105 and the substrate 101, absorbing stress generated by thermal expansion differences through its own deformation.

[0030] Furthermore, the polyurethane elastomer is a type of elastomer that can be plasticized by heating and dissolved by solvents. It has excellent comprehensive properties such as high strength, high toughness, wear resistance, and oil resistance, which can meet the requirements for setting the transition layer 104 in the LED display module.

[0031] Polydimethylsiloxane (PDMS) is an elastic polymer with excellent electrical insulation and heat resistance; the nanocomposite silicone gel has good elastic properties, which can meet the requirements of the transition layer 104 for absorbing the expansion and contraction stress between the substrate 101 and the encapsulation layer 105.

[0032] Specifically, the thickness of the transition layer 104 covering the sidewalls of the LED beads 103 is h3, and the thickness of the transition layer 104 covering the top surface of the LED beads 103 is h4. The constraint relationship between h3 and h4 is: h3 > h4. The thickness h3 of the transition layer 104 covering the sidewalls is set to be greater than the thickness h4 of the top surface. The increased thickness of the transition layer 104 in the sidewall region can absorb more lateral shear stress through material deformation, while the thinner transition layer 104 in the top surface region can maintain light transmittance while avoiding thermal stress transmission paths, thus ensuring that the LED display module has good light output efficiency, that is, ensuring that the LED display module has good display effect. At the same time, a sufficient amount of transition layer 104 colloid can be filled between each LED bead 103 to meet the absorption requirements of the transition layer 104 for the expansion and contraction stress of the substrate 101 and the encapsulation layer 105.

[0033] Furthermore, the transition layer 104 is filled with carbon powder, making it a black colloid. By setting the thickness of the transition layer 104 on the sidewall of the LED bead 103 to be greater than the thickness of the transition layer 104 on the top surface of the LED bead 103, the transition layer 104 on the sidewall of the LED bead 103 can serve as a light emission reference for the LED bead 103, thereby enhancing the light emission efficiency of the LED bead 103 and effectively improving the display effect of the LED display module.

[0034] Specifically, the thermal expansion coefficient of the encapsulation layer 105 is P1, and the value of P1 ranges from 15ppm / ℃ to 20ppm / ℃. The encapsulation layer 105 is made of one of the following materials: encapsulating adhesive with highly filled inorganic nanoparticles, silicone / polyurethane blend encapsulating adhesive, or active hollow glass microsphere composite encapsulating adhesive. The thermal expansion coefficient of the substrate 101 is P2, and the value of P2 ranges from 12ppm / ℃ to 18ppm / ℃. This difference in thermal expansion between the substrate 101 and the encapsulation layer 105 can easily lead to a large difference in thermal expansion. Specifically, when the encapsulation layer 105 is directly bonded to the substrate 101, excessive shear stress at the bonding interface can easily occur, causing the encapsulation layer 105 to warp. By providing a transition layer 104 structure, the transition layer 104 can absorb the expansion and contraction stress between the substrate 101 and the encapsulation layer 105, thereby reducing the risk of warping between the encapsulation layer 105 and the substrate 101.

[0035] Furthermore, the substrate 101 is made of a material with a high TG point. TG (Glass Transition Temperature) is the critical temperature value for the physical state transition of a material. Using a substrate 101 material with a high TG point gives the substrate 101 good structural stability. Below the heating temperature of the TG point, the substrate 101 can maintain the physical properties of the glass state and has sufficient hardness to meet the die bonding and mounting requirements of electronic devices, thereby meeting the manufacturing and processing requirements of the LED display module.

[0036] Specifically, the shrinkage rate of the encapsulation layer 105 is 'a', and the value of 'a' ranges from 0.1% to 0.7%. The shrinkage rate of the encapsulation layer 105 can be adjusted by changing the material composition of the encapsulation layer 105. By adding inorganic nanoparticles or hollow glass microspheres, the volume change during the curing process can be controlled, reducing the volume shrinkage change of the encapsulation layer 105 during the encapsulation process. In conjunction with the transition layer 104, which absorbs some stress through elastic deformation, the rigid interface is prevented from directly transmitting shrinkage stress to the substrate 101. This ensures the encapsulation reliability of the LED display module when the substrate 101 is encapsulated.

[0037] Specifically, the expansion and contraction stress between the transition layer 104 and the substrate 101 satisfies the condition that the interfacial shear stress τ is less than the cohesive strength of the colloid. During the encapsulation of the LED display module, the encapsulation layer 105 and the substrate 101 experience relative displacement due to the difference in their coefficients of thermal expansion. At this time, the transition layer 104 absorbs part of the stress through its own elastic deformation. Since the interfacial shear stress τ is constrained to be less than the cohesive strength of the colloid, the colloid material will not experience internal fracture or interfacial delamination, thereby improving the reliability and stability of the encapsulation.

[0038] Furthermore, the interfacial shear stress τ satisfies the calculation formula: ; in, Let c be the elastic modulus of the encapsulating adhesive. For the encapsulating adhesive, Poisson's ratio, For CTE difference, Let c be a function of the thickness ratio of the adhesive layer c to the substrate s. ,when When the substrate 101 is a rigid substrate, 0.75≤ ≤1.25.

[0039] Furthermore, the cohesive strength of the silicone adhesive ranges from 3 MPa to 8 MPa, while the cohesive strength of the high-strength epoxy adhesive ranges from 15 MPa to 30 MPa. By setting the interfacial shear stress τ to be less than the cohesive strength of the adhesive, good bonding between different materials can be achieved.

[0040] This invention provides an LED display module. By covering the surface of several LED beads 103 with a transition layer 104, the difference in the coefficient of thermal expansion of the materials of the substrate 101, the transition layer 104, and the encapsulation layer 105 of the LED display module is reduced. In conjunction with the material adjustment of the encapsulation colloid, the coefficient of thermal expansion of the materials of each layer of colloid within the LED display module is made different, thereby reducing the risk of warping and bending of the encapsulation colloid of the encapsulated LED display module and improving the reliability of the LED display module.

[0041] Example 2: Figure 2 A flowchart illustrating a method for fabricating an LED display module according to an embodiment of the present invention is shown. The method comprises: S11: Mount several LED beads on the substrate and bake and dry them.

[0042] Several LED beads are mounted on corresponding positions on the substrate, forming an array of LED beads. This arrangement of LED beads meets the display requirements of the screen. By placing the substrate with the LED beads in an oven and baking it, moisture and other volatiles in the substrate and LED beads can be evaporated and removed.

[0043] Furthermore, the substrate after LED chip mounting is baked for 12 hours to ensure the reliability of the baking process for the substrate and LED chips, remove moisture from the substrate and LED chips, thereby improving the structural packaging reliability and operational stability of the LED chips on the substrate.

[0044] The 12-hour low-temperature baking process effectively evaporates moisture from the substrate and the internal structure of the LED chips. The LED module can be placed in an oven with circulating hot air, which accelerates the evaporation of moisture from the substrate and LED chips, improving the drying effect. This process effectively vaporizes and removes trace amounts of moisture that have penetrated the PCB substrate, component packages, and pad gaps through environmental adsorption, preventing these moisture particles from instantly vaporizing and affecting the internal structure of the package during subsequent high-temperature reflow soldering.

[0045] S12: Sandblast the substrate that has completed the baking and drying process to obtain the initial display board.

[0046] In the precision manufacturing process of LED displays, baking and sandblasting are common pretreatment procedures that can treat the surface of the substrate and LED beads, providing a foundation for subsequent encapsulation operations with various molding materials, ensuring the reliability of LED display module products, and effectively improving their optical performance and service life.

[0047] Sandblasting is an extremely precise surface modification technology. For rosin-based flux residues used in the welding process, sandblasting can remove the rosin resin residues by grinding. Sandblasting can completely remove rosin residues, oxide layers, dust particles, and other organic contaminants that have become brittle after baking. At the same time, it can avoid damage to the substrate and LED chip surfaces. Based on sandblasting, the surface structure characteristics of the substrate and LED chips can be optimized to improve the stability and reliability of subsequent packaging, and at the same time, it can improve the reliability of the LED display module packaging structure.

[0048] S13: Prepare a transition layer on the initial display panel by dip-coating.

[0049] In this embodiment, the transition layer of the LED display module is prepared by dip-coating method. The substrate is vertically immersed in a flexible transition layer material solution with the LED beads facing down for full wetting, so that the flexible transition layer material solution can fully cover the surface of the LED beads on the substrate and fill the spaces between the LED beads.

[0050] Furthermore, the module is vertically lifted at a constant speed of 0.1 mm / s to 3 mm / s. During the lifting process, the LED display module is lifted at a uniform speed, and the LED display module is moved smoothly upward by the handling equipment, thereby avoiding liquid surface vibration and ensuring the uniformity of the transition layer covering the substrate and LED beads, which meets the plastic encapsulation protection requirements of the substrate and several LED beads.

[0051] The lifting speed of the LED display module, the solution viscosity, and gravity work together to control the forming thickness of the transition layer, so that the transition layer can meet the packaging requirements of the LED display module.

[0052] The solution viscosity ranges from 30cp to 200cp. When the LED display module is lifted from the solution and exposed to the air, the solution film attached to the substrate and LED beads can be transformed into a "wet gel film" in the air. By controlling the ambient temperature and humidity, the solvent of the wet gel film is set to evaporate, thereby forming a "dry gel film" on the surface of the substrate and LED beads. This allows the gel film to be relatively fixed on the surface of the substrate and LED beads. After drying, the dry gel film can be transformed into the transition layer.

[0053] S14: Apply encapsulating adhesive to the surface of the transition layer to form a plastic-encapsulated structure; The LED display module with the transition layer prepared is encapsulated. Encapsulating adhesive is uniformly coated on the release film. The side of the LED display module with the transition layer, i.e., the light-emitting surface of several LED beads, is placed face down in the encapsulating adhesive of the release film. Through vacuum treatment, the encapsulating adhesive can adhere to several LED beads of the LED display module and form a plastic encapsulation structure on several LED beads, so that the encapsulating adhesive can meet the plastic encapsulation requirements of several LED beads in the LED display module.

[0054] S15: After the plastic encapsulation structure is cured and shaped, the LED display module is obtained by trimming the encapsulation layer.

[0055] Specifically, by vacuuming and allowing the LED display module and the molding structure to stand still, the molding structure is cured and shaped, forming an encapsulation layer on several LED beads. When the molding structure is initially cured and shaped, the encapsulating adhesive of the molding structure is initially shaped and maintains a certain elasticity, which can meet the requirements of the release film removal operation. After lifting one corner of the release film, the operator or a robotic arm holds one corner of the release film and performs the film removal operation. The film removal operation is performed at a small angle and a slow and uniform speed to ensure that the release film can be peeled off evenly.

[0056] Furthermore, the LED display module after the film peeling operation is completed is cut and trimmed to remove the residual adhesive from the encapsulation, ensuring the flatness of the overall encapsulation structure of the display module.

[0057] This invention provides a method for manufacturing an LED display module. A transition layer is coated onto the surface of several LED chips, and this transition layer is filled between the LED chips to achieve encapsulation protection. By coating the surface of the LED chips with a transition layer, the difference in the coefficients of thermal expansion between the substrate material, the transition layer, and the encapsulation layer of the LED display module is reduced, thereby reducing the risk of warping and bending of the encapsulation adhesive in the encapsulated LED display module and improving the reliability of the LED display module.

[0058] Furthermore, the above provides a detailed description of an LED display module and its preparation method provided by the embodiments of the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. An LED display module, characterized in that, The display module includes: a substrate, electronic components, LED beads, a transition layer, and an encapsulation layer; The LED beads are disposed on the substrate and housed within the encapsulation layer. The transition layer is disposed between the LED beads and the encapsulation layer and covers the surface of the LED beads. The surface of the encapsulation layer is the display surface of the display module. The height difference between the highest and lowest points of the display surface of the display module is h1, and the value range of h1 satisfies: 0≤h1≤0.5mm.

2. The LED display module as described in claim 1, characterized in that, The transition layer is made of a flexible material, and the elastic modulus of the transition layer is K, with the value of K ranging from 0.1 MPa to 1 MPa.

3. The LED display module as described in claim 1, characterized in that, The thickness of the transition layer is h2, and the value of h2 is in the range of 5μm≤h2≤30μm.

4. The LED display module as described in claim 1, characterized in that, The transition layer is made of one of the following materials: silicone rubber, polyurethane elastomer, modified PDMS, or nanocomposite organosilicon gel.

5. The LED display module as described in claim 1, characterized in that, The thickness of the transition layer covering the sidewall of the LED bead is h3, and the thickness of the transition layer covering the top surface of the LED bead is h4. The constraint relationship between h3 and h4 is: h3 > h4.

6. The LED display module as described in claim 1, characterized in that, The thermal expansion coefficient of the encapsulation layer is P1, and the value of P1 is in the range of 15ppm / ℃≤P1≤20ppm / ℃.

7. The LED display module as described in claim 1, characterized in that, The shrinkage rate of the encapsulation layer is 'a', and the value of 'a' ranges from 0.1% to 0.7%.

8. The LED display module as described in claim 1, characterized in that, The substrate material has a coefficient of thermal expansion of P2, and the value of P2 is in the range of 12ppm / ℃≤P2≤18ppm / ℃.

9. The LED display module as described in claim 1, characterized in that, The expansion and contraction stress between the transition layer and the substrate satisfies the condition that the interfacial shear stress τ is less than the cohesive strength of the colloid.

10. The LED display module as described in claim 1, characterized in that, The interfacial shear stress τ satisfies the calculation formula: ； in, Let c be the elastic modulus of the encapsulating adhesive. For the encapsulating adhesive, Poisson's ratio, For CTE difference, Let c be a function of the thickness ratio of the adhesive layer c to the substrate s. ,when When the substrate is a rigid substrate, 0.75≤ ≤1.

25.

11. A method for manufacturing an LED display module, characterized in that, The preparation method is used to prepare the LED display module as described in any one of claims 1 to 10, the preparation method comprising: Several LED beads are mounted on the substrate and then baked and dried. The substrate that has undergone baking and drying is sandblasted to obtain the initial display board. A transition layer was prepared on the initial substrate of the display screen using an dip-coating method. Encapsulating adhesive is applied to the surface of the transition layer to form a plastic-encapsulated structure; After the plastic encapsulation structure has been cured and shaped, the LED display module is obtained by trimming the encapsulation layer.

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