An optical encapsulation film and a preparation method thereof, and a removal encapsulation method of an LED module

Abstract

The application provides an optical packaging film and a preparation method thereof, and a removal packaging method of an LED module, and belongs to the fields of intelligent polymer materials and advanced optical packaging technologies; the technical problems to be solved are that the existing technologies have complex structures, low repair precision and high risk of thermal damage; the technical scheme for solving the technical problems is that the optical packaging film comprises a base material layer and a functional adhesive layer; the functional adhesive layer is a composite dynamic bonding phase change polymer; the composite dynamic bonding phase change polymer comprises near-infrared light-to-heat conversion particles and at least two different dynamic covalent bond systems; the dynamic covalent bond systems are used for realizing the reversible response characteristics of the functional adhesive layer in a wide temperature range and under multiple conditions; and the near-infrared light-to-heat conversion particles are used for efficient heat generation and participate in dynamic bonding; the application is applied to the advanced packaging and repair of high-precision optoelectronic devices such as Mini / Micro LED and COB.

Description

Technical Field

[0001] This application relates to the fields of intelligent polymer materials and advanced optical packaging technology, and in particular to an optical packaging film and its preparation method, and a method for removing the packaging of an LED module. Background Technology

[0002] In the fields of high-end displays and semiconductor packaging, reworkability is key to improving yield and reducing manufacturing costs. Existing rework technologies mostly employ multi-layer structures (such as thermosetting / thermoplastic layers), achieving interface softening through overall heating. This approach suffers from problems such as complex structures, low rework accuracy, and high risk of thermal damage.

[0003] The authorized prior art document CN120461985A discloses a bilayer near-infrared photoresponsive liquid crystal elastomer that achieves thermo-press bonding and photothermal response through dynamic acetal bonds. However, this material system has the following limitations: it uses a single dynamic bonding system (acetal bonds), which limits the response conditions and reliability; the photothermal conversion particles are simple dopants, resulting in poor dispersion and interfacial bonding; the material has a bilayer structure, which still presents interfacial matching problems; and its function is limited, lacking integration of thermal management, optical conversion, and other encapsulation-required performance. Summary of the Invention

[0004] To address the aforementioned technical problems, this application proposes an optical encapsulation film and its preparation method, as well as a method for removing the encapsulation from an LED module.

[0005] The technical solution adopted in this application is: an optical encapsulation film, including a substrate layer and a functional adhesive layer, wherein the functional adhesive layer is a composite dynamically bonded phase change polymer, the composite dynamically bonded phase change polymer includes near-infrared photothermal conversion particles and at least two different dynamic covalent bond systems, the dynamic covalent bond system is used to realize the wide temperature range and multi-condition reversible response characteristics of the functional adhesive layer, and the near-infrared photothermal conversion particles are used for efficient heat generation and participate in dynamic bonding.

[0006] Furthermore, at least two different dynamic covalent bond systems are any two or more of the following: Diels-Alder bond, oxime-carboxylic acid bond, borate ester bond, and acetal bond.

[0007] Furthermore, the near-infrared photothermal conversion particles include a core and a shell, wherein the core is any one of gold nanorods, black phosphorus quantum dots, modified tungsten oxide nanowires, or copper phosphorus sulfur nanosheets, and the shell is silicon dioxide or polydopamine.

[0008] Furthermore, the surface of the grain shell is provided with functional groups, which are any one of furanyl, maleimide, or oxime groups, and these functional groups are used to chemically bond with the composite dynamic bonding phase change polymer.

[0009] Furthermore, in the functional adhesive layer, the concentration of near-infrared photothermal conversion particles on the side closer to the substrate layer is lower than the concentration of near-infrared photothermal conversion particles on the side farther from the substrate layer.

[0010] Furthermore, the functional adhesive layer also includes a composite filler, which is a particle formed by loading phosphor onto the surface of a thermally conductive filler, or a particle formed by coating a thermally conductive layer onto the surface of a scattering particle.

[0011] Furthermore, the functional adhesive layer also includes a composite filler, which is a sheet-like composite particle formed by loading YAG:Ce phosphor onto the surface of boron nitride nanosheets, or an alumina spherical composite particle coated with titanium dioxide.

[0012] A method for preparing an optical encapsulation film as described above includes the following steps: Step 1: The prepolymer constituting the composite dynamically bonded phase change polymer is mixed with the crosslinking agent, the near-infrared photothermal conversion particles, the composite filler and solvent, and then stirred and ultrasonically dispersed to obtain a homogeneous colloid. Step 2: Using a multi-segment coating process, the homogeneous adhesive containing different concentrations of the near-infrared photothermal conversion particles is coated layer by layer onto the substrate layer. After preheating, it is pre-cured by ultraviolet light irradiation to form an incompletely cured adhesive layer with gradient distribution characteristics. Step 3: The incompletely cured adhesive layer is bonded to the module under heating and pressurization conditions. The heating and pressurization conditions trigger the final crosslinking reaction of the composite dynamic bonded phase change polymer, completing the encapsulation and curing, followed by a curing treatment.

[0013] A method for removing the encapsulation from an LED module, wherein the LED module is covered with the optical encapsulation film as described above, includes the following steps: Step 1: Irradiate the optical encapsulation film with a first wavelength and a first power density to preheat the functional adhesive layer; Step 2: Irradiate the optical encapsulation film with a second wavelength and / or a second power density to reduce the adhesion of the functional adhesive layer to a peelable range, thereby separating the optical encapsulation film from the LED module.

[0014] Furthermore, the second power density is higher than the first power density.

[0015] The advantages of this application compared to existing technologies are as follows: it provides a wider reversible response window and higher network stability and reliability; the core-shell structure and gradient distribution of near-infrared photothermal conversion particles achieve energy localization and interface directional conduction, significantly improving rework accuracy and efficiency, and reducing the risk of thermal damage; the single adhesive layer structure avoids the matching problem of multi-layer interfaces, and the integrated performance of thermal conductivity and optical conversion is achieved through multifunctional composite fillers, simplifying the packaging structure and improving overall performance; the UV and thermal dual curing process has good compatibility with existing packaging production lines, and gradient coating and in-situ curing technologies improve film quality and bonding strength; the multi-stage light irradiation removal packaging method provides a flexible and controllable process window to adapt to the sensitivity requirements of different modules. Attached Figure Description

[0016] The following description, in conjunction with the accompanying drawings, further illustrates this application: Figure 1 This is a schematic diagram of the optical encapsulation film in this application; Figure 2 This is a schematic diagram of the reversible chemical mechanism of the dynamic covalent bond system in this application; Figure 3 This is a schematic diagram of the localized interfacial thermal effect generated by near-infrared photothermal conversion particles under near-infrared light irradiation in this application. Figure 4 This is a flowchart illustrating the method for removing the LED module encapsulation in this application; In the figure: 1 is the substrate layer, 2 is the functional adhesive layer, 3 is the near-infrared photothermal conversion particle, 4 is the Diels-Alder bond, 5 is the oxime-carboxylic acid bond, 6 is the particle core, 7 is the particle shell, 8 is the functional group, 9 is the near-infrared light, A is the heating encapsulation to formation, B is the near-infrared light irradiation to dissociation, and C is the heat gradient conduction. Detailed Implementation

[0017] like Figures 1 to 4 As shown, this application provides an optical encapsulation film, including a substrate layer 1 and a functional adhesive layer 2. The functional adhesive layer 2 is a composite dynamically bonded phase change polymer, which includes near-infrared photothermal conversion particles 3 and at least two different dynamic covalent bond systems. The dynamic covalent bond systems are used to achieve the wide-temperature-range, multi-condition reversible response characteristics of the functional adhesive layer 2. The near-infrared photothermal conversion particles 3 are used for efficient heat generation and participate in dynamic bonding. The at least two different dynamic covalent bond systems are any two or more of Diels-Alder bonds 4, oxime-carboxylic acid bonds 5, borate ester bonds, and acetal bonds.

[0018] In this embodiment, when the dynamic covalent bond system is a composite system of Diels-Alder bond 4 and oxime-carboxylic acid bond 5, it is formed by a synergistic crosslinking reaction of furan-terminated polyurethane prepolymer, oxime-terminated polyurethane prepolymer, bismaleimide crosslinking agent, and aldehyde crosslinking agent, wherein the mass ratio of furan-terminated polyurethane prepolymer to oxime-terminated polyurethane prepolymer is (70-90):(10-30). The two dynamic bonding systems form an interpenetrating or synergistically crosslinked structure in the network, endowing the functional adhesive layer 2 with wide temperature range and reversible response characteristics under multiple conditions.

[0019] The near-infrared photothermal conversion particles 3 include a core 6 and a shell 7. The core 6 is a high photothermal conversion efficiency material, including any one of gold nanorods, black phosphorus quantum dots, modified tungsten oxide nanowires, or copper phosphorus sulfur nanosheets. The shell 7 is silica or polydopamine. Functional groups 8 are disposed on the surface of the shell 7. The functional groups 8 are any one of furanyl, maleimide, or oxime groups. The functional groups 8 participate in dynamic bonding, enhancing interfacial bonding and dispersion stability. In the functional adhesive layer 2, the concentration of the near-infrared photothermal conversion particles 3 on the side closer to the substrate layer 1 is lower than the concentration on the side farther from the substrate layer 1, i.e., the particle mass concentration on the side closer to the substrate layer 1 is ≤0.5%, and the particle mass concentration on the side farther from the substrate layer 1 is ≥1.5%. This structural design can efficiently concentrate the heat during encapsulation, achieving rapid softening of the functional adhesive layer 2 while minimizing heat conduction to the module body.

[0020] The functional adhesive layer 2 also includes composite fillers, which are particles formed by loading phosphors onto the surface of thermally conductive fillers, or particles formed by coating a thermally conductive layer onto the surface of scattering particles, or sheet-like composite particles formed by loading YAG:Ce phosphors onto the surface of boron nitride nanosheets (providing both thermal conductivity and color conversion functions), or alumina spherical composite particles coated with titanium dioxide (providing both light scattering and thermal conductivity functions). This design achieves synergistic control of multiple performance parameters such as heat, light, and force within a single adhesive layer.

[0021] A method for preparing the above-mentioned optical encapsulation film includes the following steps: Step 1: The prepolymer constituting the composite dynamic bonded phase change polymer is mixed with the crosslinking agent, the near-infrared photothermal conversion particles 3, the composite filler and solvent, and then stirred and ultrasonically dispersed to obtain a homogeneous colloid. Step 2: Using a multi-segment coating process, the homogeneous adhesive containing different concentrations of the near-infrared photothermal conversion particles 3 is coated layer by layer onto the substrate layer 1. After preheating, it is pre-cured by ultraviolet light irradiation to form an incompletely cured adhesive layer with gradient distribution characteristics. Step 3: The incompletely cured adhesive layer is bonded to the module under heating and pressurization conditions. The heating and pressurization conditions trigger the final crosslinking reaction of the composite dynamic bonded phase change polymer, completing the encapsulation and curing, followed by a curing treatment.

[0022] A method for removing the encapsulation from an LED module, wherein the LED module is covered with the optical encapsulation film as described above, includes the following steps: Step 1: Irradiate the optical encapsulation film with a first wavelength and a first power density to preheat the functional adhesive layer 2; Step 2: Irradiate the optical encapsulation film with a second wavelength and / or a second power density, reducing the adhesion of the functional adhesive layer 2 to a peelable range, thereby separating the optical encapsulation film from the LED module. The second power density is higher than the first power density. The multi-stage near-infrared light irradiation strategy is either dual-wavelength alternating irradiation, where the first wavelength is 800-850nm and the second wavelength is 980-1064nm; or power gradient modulation irradiation, where the first power density is 1-2W / cm² and the second power density is 3-5W / cm².

[0023] In the embodiments of this application, the method for removing the encapsulation of the LED module adopts a multi-stage near-infrared light irradiation strategy, such as alternating dual-wavelength irradiation (e.g., first 800nm ​​low-power preheating, then 1064nm high-power triggering reverse reaction) or power gradient modulation irradiation. This method can achieve faster, more accurate, and less thermally affected non-destructive stripping.

[0024] Example 1: Preparation and Performance of Composite Dynamically Bonded Optical Encapsulation Film Formulation: 80g furan-terminated polyurethane prepolymer, 20g oxime-terminated polyurethane prepolymer, 12g bismaleimide crosslinking agent, 5g aldehyde crosslinking agent, 1.8g total of core-shell structured gold nanorods@SiO2-furan particles (concentration gradient design: top layer 2.2wt%, middle layer 0.8wt%, bottom layer 0%), 2.5g boron nitride@YAG:Ce composite filler, and 200g DMF solvent.

[0025] Preparation: The components were mixed and stirred at 50°C for 4 hours, then ultrasonically dispersed at 400W for 20 minutes. A three-stage coating process was used to coat the mixture onto a 100μm thick COP substrate. After each coating, the film was preheated at 90°C for 1 minute and irradiated with 365nm UV light for 3 minutes. Subsequently, the film was pressed under simulated encapsulation conditions (85°C, 0.8MPa) for 5 minutes, and then cured at 50°C for 20 hours to obtain an encapsulation film with a functional adhesive layer thickness of approximately 50μm.

[0026] Performance: Initial peel strength 168 N / cm. After irradiation with dual-wavelength near-infrared laser (800 nm, 1.5 W / cm², 8 s → 1064 nm, 4.0 W / cm², 10 s), the interfacial peel strength decreased to 7 N / cm. After aging at 85℃ / 85%RH for 500 h, the strength retention rate was >92%. The thermal resistance of the packaged module decreased by 15%, and the color uniformity (Δu'v') was <0.003.

[0027] Example 2: Encapsulation film containing multifunctional scattering-thermal conductive filler Formula: 100g furan-terminated polyurethane prepolymer, 15g bismaleimide crosslinking agent, 1.5g core-shell black phosphorus quantum dots@PDA-oxime particles (gradient distribution), 3.0g titanium dioxide-coated alumina composite filler (particle size 200nm, TiO2 shell thickness 20nm), and 180g PMA solvent.

[0028] Preparation and Performance: The preparation process is the same as in Example 1. The resulting film has a visible light scattering efficiency >90% and an in-plane thermal conductivity of 1.2 W / m·K. Using power gradient modulation to remove the encapsulation (980nm laser: 1W / cm²→3W / cm²→1W / cm² three-stage irradiation, total time 18s), precise peeling of <100μm can be achieved, with a temperature rise of <3℃ between adjacent modules. The film transmittance is >88%, and the haze is >85%.

[0029] Example 3: Low-temperature flexible encapsulation film Formula: 60g furan-terminated polyurethane prepolymer, 40g oxime-terminated polyurethane prepolymer (to improve low-temperature flexibility), 18g total crosslinking agent, 1.0g gold nanorods@SiO2-maleimide particles, and 2.0g flexible thermally conductive filler (silane-modified alumina).

[0030] Performance: The glass transition temperature (Tg) of this film is as low as -25℃, making it suitable for flexible display modules; it can achieve a firm encapsulation (peel strength >150N / cm) by hot pressing at a low temperature of 60℃; when removing the encapsulation, only 12s of irradiation with a 980nm laser (2.5W / cm²) is required to achieve softening and peeling at an interface temperature of 80℃, which greatly avoids damage to the flexible substrate caused by high temperature.

[0031] Example 4: Reliability Testing Without Packaging The encapsulation film prepared in Example 1 was subjected to repeated encapsulation removal tests. A "encapsulation-re-encapsulation" cycle was simulated five times in the same area. The results showed that after the fifth re-encapsulation, its peel strength remained above 88% of the initial strength, and there was no visible damage or residue at the interface, demonstrating that the material of this invention has good reversible cycle reliability.

[0032] In summary, this application constructs a dynamic covalent bond system (such as the synergistic effect of Diels-Alder bond 4 and oxime-carboxylic acid bond 5) and combines the core-shell design and gradient distribution of near-infrared photothermal conversion particles 3, enabling the optical encapsulation film of this application to form a high-strength bond (peel strength ≥160N / cm) during the initial hot pressing. During the removal of the encapsulation, multi-stage near-infrared light irradiation can achieve a precise and rapid decrease in the interfacial adhesion (peel strength ≤10N / cm), thereby completing the local and non-destructive peeling of the failed LED module.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An optical encapsulation film, comprising a substrate layer (1) and a functional adhesive layer (2), characterized in that: The functional adhesive layer (2) is a composite dynamic bonded phase change polymer. The composite dynamic bonded phase change polymer includes near-infrared photothermal conversion particles (3) and at least two different dynamic covalent bond systems. The dynamic covalent bond system is used to realize the wide temperature range and multi-condition reversible response characteristics of the functional adhesive layer (2). The near-infrared photothermal conversion particles (3) are used for efficient heat generation and participate in dynamic bonding.

2. The optical encapsulation film according to claim 1, characterized in that: At least two different dynamic covalent bond systems are any two or more of the following: Diels-Alder bond (4), oxime-carboxylic acid bond (5), borate ester bond, and acetal bond.

3. The optical encapsulation film according to claim 2, characterized in that: The near-infrared photothermal conversion particles (3) include a core (6) and a shell (7). The core (6) is any one of gold nanorods, black phosphorus quantum dots, modified tungsten oxide nanowires or copper phosphorus sulfur nanosheets, and the shell (7) is silicon dioxide or polydopamine.

4. The optical encapsulation film according to claim 3, characterized in that: The surface of the shell (7) is provided with functional groups (8), which are any one of furanyl, maleimide or oxime groups, and are used to chemically bond with the composite dynamic bonding phase change polymer.

5. An optical encapsulation film according to any one of claims 2-4, characterized in that: In the functional adhesive layer (2), the concentration of the near-infrared photothermal conversion particles (3) on the side closer to the substrate layer (1) is lower than the concentration of the near-infrared photothermal conversion particles (3) on the side farther away from the substrate layer (1).

6. The optical encapsulation film according to claim 5, characterized in that: The functional adhesive layer (2) also includes a composite filler, which is a particle formed by loading phosphor on the surface of a thermally conductive filler, or a particle formed by coating a thermally conductive layer on the surface of a scattering particle.

7. An optical encapsulation film according to claim 5, characterized in that: The functional adhesive layer (2) also includes a composite filler, which is a sheet-like composite particle formed by loading YAG:Ce phosphor on the surface of boron nitride nanosheets, or an alumina spherical composite particle coated with titanium dioxide.

8. A method for preparing an optical encapsulation film as described in claim 6 or 7, characterized in that, Includes the following steps: Step 1: The prepolymer constituting the composite dynamic bonded phase change polymer is mixed with the crosslinking agent, the near-infrared photothermal conversion particles (3), the composite filler and the solvent, and then stirred and ultrasonically dispersed to obtain a homogeneous colloid. Step 2: Using a multi-segment coating process, the homogeneous adhesive liquid containing different concentrations of the near-infrared photothermal conversion particles (3) is coated layer by layer onto the substrate layer (1). After preheating, it is pre-cured by ultraviolet light irradiation to form an incompletely cured adhesive layer with gradient distribution characteristics. Step 3: The incompletely cured adhesive layer is bonded to the module under heating and pressurization conditions. The heating and pressurization conditions trigger the final crosslinking reaction of the composite dynamic bonded phase change polymer, completing the encapsulation and curing, followed by a curing treatment.

9. A method for removing the encapsulation from an LED module, wherein the LED module is covered with an optical encapsulation film as described in claim 6 or 7, characterized in that, Includes the following steps: Step 1: Irradiate the optical encapsulation film with a first wavelength and a first power density to preheat the functional adhesive layer (2); Step 2: Irradiate the optical encapsulation film with a second wavelength and / or a second power density to reduce the adhesion of the functional adhesive layer (2) to a peelable range, thereby separating the optical encapsulation film from the LED module.

10. A method for removing the encapsulation of an LED module according to claim 9, characterized in that: The second power density is higher than the first power density.

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