Preparation method of LED packaging structure and LED packaging structure

Abstract

The invention relates to the technical field of display equipment, in particular to a preparation method of an LED packaging structure and the LED packaging structure.The preparation method comprises the following steps that a fluorescent sheet is provided, edge packaging is conducted on the fluorescent sheet, a fluorescent sheet combined structure is formed, and the fluorescent sheet combined structure comprises the fluorescent sheet and transparent adhesive tape arranged on the side face of the fluorescent sheet; an inclined structure is formed between the transparent adhesive tape and the side surface of the fluorescent sheet; a substrate is provided, the LED chip is fixed on the substrate, and the fluorescent sheet combination structure is attached to the top face of the side, away from the substrate, of the LED chip; glue is dispensed around the fluorescent sheet combined structure and the LED chip to form a packaging glue layer, the fluorescent sheet and the transparent glue are integrated in advance in edge packaging, and the subsequent independent steps of gap filling and edge sealing are reduced; the formed inclined structure guides the light to the light emitting direction of the front surface of the fluorescent sheet, the inclined structure provides a non-vertical surface, a transition interface is increased, and scattering is reduced.

Description

Technical Field

[0001] This invention relates to the field of display device technology, and in particular to a method for preparing an LED packaging structure and the LED packaging structure itself. Background Technology

[0002] With the development of LED lighting technology, the requirements for light source performance in various fields are constantly increasing. In automotive high and low beam lighting scenarios, high-power LED products with small-sized emitting surfaces are highly favored because they can achieve high light concentration, improve light convergence efficiency, and adapt to the installation needs of compact spaces. However, achieving a small emitting surface often relies on small-sized chips, which leads to a sharp increase in the current density inside the chip. This not only significantly reduces luminous efficiency but also easily generates local hot spots, affecting lighting quality and product lifespan.

[0003] Currently, in the domestic market, small-sized flip chips are mostly used to meet the functional requirements of small light-emitting surfaces. However, small-sized flip chips have poor current resistance and insufficient brightness. Therefore, in order to obtain products with high brightness of small light-emitting surfaces, the industry has introduced processes such as vertical chip packaging. However, the high manufacturing cost has restricted the popularization of vertical chip packaging. Summary of the Invention

[0004] To address the high cost of existing methods for obtaining small-sized light-emitting surfaces, this invention provides a method for preparing an LED packaging structure and the LED packaging structure itself.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing an LED packaging structure, the method comprising the following steps: providing a phosphor sheet, edge-encapsulating the phosphor sheet to form a phosphor sheet assembly structure, the phosphor sheet assembly structure comprising the phosphor sheet and a transparent adhesive disposed on the side of the phosphor sheet, the transparent adhesive forming an inclined structure with the side of the phosphor sheet; providing a substrate, fixing an LED chip on the substrate, attaching the phosphor sheet assembly structure to the top surface of the LED chip on the side away from the substrate, wherein the phosphor sheet includes a light-emitting surface on the side away from the LED chip; applying adhesive around the phosphor sheet assembly structure and the LED chip to form an encapsulating adhesive layer, the encapsulating adhesive layer, the phosphor sheet assembly structure, the LED chip, and the substrate forming the LED packaging structure.

[0006] Preferably, a fluorescent sheet is provided, and the fluorescent sheet is edge-encapsulated to form a fluorescent sheet assembly structure. The fluorescent sheet assembly structure includes the fluorescent sheet and a transparent adhesive disposed on the side of the fluorescent sheet. An inclined structure is formed between the transparent adhesive and the side of the fluorescent sheet. The method includes the following steps: providing a double-sided film; arranging the fluorescent sheet in an array on the double-sided film; applying transparent adhesive to the four sides of the fluorescent sheet and forming the inclined structure on the side of the fluorescent sheet; and cutting the transparent adhesive to form a single fluorescent sheet assembly structure.

[0007] Preferably, providing a double-sided film and arranging the fluorescent sheet in an array onto the double-sided film includes the following steps: providing a heat-resistant substrate and attaching the double-sided film including the fluorescent sheet onto the heat-resistant substrate.

[0008] Preferably, cutting the transparent adhesive to form a single fluorescent sheet assembly structure includes the following steps: cutting the transparent adhesive with a water jet to form a single fluorescent sheet assembly structure; and dehumidifying the cut fluorescent sheet assembly structure.

[0009] Preferably, after cutting the transparent adhesive to form a single fluorescent sheet assembly structure, the method further includes: providing a blue film, and casting the cut fluorescent sheet assembly structure onto the blue film in an array, wherein the fluorescent sheet includes a light-incident surface near the LED chip, and the light-incident surface is bonded to the blue film.

[0010] Preferably, providing a substrate, fixing the LED chip on the substrate, and attaching the phosphor assembly structure to the top surface of the LED chip on the side away from the substrate includes the following steps: fixing the LED chip to the substrate by hot-pressing eutectic bonding or reflow soldering eutectic bonding; and attaching the phosphor assembly structure to the top surface of the LED chip by die bonding adhesive.

[0011] Preferably, the angle between the transparent adhesive and the side of the fluorescent sheet forming the inclined structure is in the range of 5°-45°, and the transparent adhesive further includes an extension surface extending in the horizontal direction.

[0012] Preferably, the refractive index of the encapsulating adhesive layer is between 1.40 and 1.55, and the height of the encapsulating adhesive layer relative to the substrate is equal to the height of the phosphor sheet relative to the substrate.

[0013] Preferably, the sum of the planar projected area of ​​the transparent adhesive and the planar projected area of ​​the fluorescent sheet is greater than or equal to the planar projected area of ​​the top surface, and the planar projected area of ​​the light-emitting surface based on the substrate is less than or equal to the planar projected area of ​​the LED chip based on the substrate.

[0014] To solve the above-mentioned technical problems, the present invention provides another technical solution as follows: an LED packaging structure, including a substrate, an LED chip electrically connected to the substrate, and a phosphor sheet disposed on the side of the LED chip away from the substrate, wherein the side of the phosphor sheet facing away from the LED chip is a light-emitting surface; the LED packaging structure further includes an encapsulating adhesive layer disposed around the LED chip and the phosphor sheet, wherein a gap is provided between the encapsulating adhesive layer and the phosphor sheet, and a transparent adhesive is disposed in the gap.

[0015] Compared with the prior art, the LED packaging structure preparation method and LED packaging structure provided by the present invention have the following beneficial effects: 1. The present invention provides a method for preparing an LED packaging structure. The edge of the phosphor sheet is a weak area. A phosphor sheet assembly structure is prepared in advance to strengthen the physical protection of the phosphor sheet. The tilted structure changes the light emission angle at the edge of the phosphor sheet, avoiding total internal reflection at the right-angle edge and improving light extraction efficiency. The encapsulating adhesive layer reflects the light emitted from the side of the LED chip to the light-emitting surface. The smaller area of ​​the phosphor sheet can concentrate the light emitted by the LED chip in the central area of ​​the entire LED packaging structure to obtain a smaller light-emitting surface. The light excited by the larger LED chip is focused and emitted from the smaller area of ​​the phosphor sheet. The large LED chip is more resistant to current. Reducing the light-emitting surface of the phosphor sheet makes it more concentrated and efficient to excite the phosphor sheet to emit white light, accurately control the light, reduce the scattering loss of the phosphor sheet, and optimize the light emission angle. The transparent adhesive wraps the right-angle edge of the phosphor sheet to form a phosphor sheet assembly structure, which provides a guiding path for the subsequent encapsulating adhesive layer dispensing process, so that the encapsulating adhesive layer covers the gap between the phosphor sheet and the chip more evenly and reduces bubbles or voids.

[0016] 2. In this embodiment of the invention, a fluorescent sheet assembly structure is pre-prepared. The fluorescent sheets are fixed by adhesive bonding on the upper and lower surfaces of the double-sided film to avoid positional shifts during array arrangement. Multiple fluorescent sheets are fixed in an array, facilitating batch processing. The inclined structure formed between the transparent adhesive and the side of the fluorescent sheet changes the emission angle of light on the side of the fluorescent sheet, reducing total internal reflection loss, improving luminous efficiency, and reducing the dark angle of the light spot. The transparent adhesive is tightly bonded to the edge of the fluorescent sheet, reducing reflection loss at the interface and improving luminous efficiency and uniformity. At the same time, the transparent adhesive can serve as a light diffusion pretreatment layer, so that some of the light emitted from the top surface of the LED chip is first scattered and homogenized by the transparent adhesive before entering the encapsulation adhesive layer for reflection. The reflected light enters the fluorescent sheet for light conversion. The transparent adhesive is cut to form a single fluorescent sheet assembly structure. Based on the fluorescent sheets fixed by the double-sided film array, the transparent adhesive is cut by water jet cutting to achieve batch segmentation, remove burrs, and ensure that the size tolerance of each individual sheet is controlled within a preset accuracy range, meeting the requirements of LED packaging structure for the uniformity of fluorescent sheet size.

[0017] 3. In this embodiment of the invention, the curing of the transparent adhesive usually requires high-temperature treatment. The heat resistance temperature of the double-sided film is greater than or equal to 150 degrees Celsius. However, the double-sided film may soften during the heating process. The double-sided film is pasted onto the heat-resistant substrate to prevent the array of fluorescent film from shifting during the heating process of the double-sided film, thus avoiding affecting the subsequent cutting accuracy. At the same time, the heat-resistant substrate can conduct heat released by the transparent adhesive during the heating and curing process, avoiding the deterioration of the fluorescent film caused by local overheating.

[0018] 4. In this embodiment of the invention, the prefabrication of the fluorescent sheet assembly structure also includes cutting and dehumidification steps. Water jet cutting is used to complete the precision processing without heat damage, ensuring the uniformity of the fluorescent sheet size. The cut surface formed by water jet cutting is free of burrs and melt layer, avoiding the micro-cracks of traditional mechanical cutting and reducing the risk of stress concentration during subsequent encapsulation. Dehumidification treatment can prevent the phosphor from deliquescing, improve the tensile strength of the transparent adhesive, and ensure the quality of the transparent adhesive curing.

[0019] 5. In this embodiment of the invention, the blue film is a silicone-based thermosetting protective film. After the phosphor sheet assembly structure is prefabricated, the phosphor sheet assembly structure is pasted onto the LED chip during the processing flow. The blue film provides adhesion and reduces the edge collapse rate of the phosphor sheet during casting and transfer.

[0020] 6. In this embodiment of the invention, the LED chip is fixed to the substrate by hot-pressing eutectic bonding or reflow soldering eutectic bonding. The phosphor assembly structure is attached to the top surface of the LED chip by die bonding adhesive, thus completing the fixation of the LED chip to the substrate and the attachment of the LED chip to the phosphor assembly structure. Hot-pressing eutectic bonding and reflow soldering eutectic bonding of the LED chip are both eutectic bonding processes. Eutectic bonding uses the metallurgical bonding of intermetallic compounds to build a low-resistance heat conduction path and a stable electrical connection, reducing the chip junction temperature and ensuring electrical stability. The die bonding adhesive process precisely controls the position and adhesive layer thickness of the phosphor assembly structure attached to the LED chip. Combined with the high-precision positioning of eutectic bonding, precise matching is achieved, ensuring the consistency of luminous efficacy and spectrum. At the same time, eutectic bonding and die bonding adhesive processes are compatible with various substrate materials such as ceramics and metals, ensuring high performance while having cost advantages for mass production.

[0021] 7. In this embodiment of the invention, the inclined structure formed by the transparent adhesive and the side of the fluorescent sheet allows light that might otherwise be lost due to reflection or refraction at the edge of the encapsulation adhesive layer to undergo a first reflection between different media before entering the fluorescent sheet. This allows more light to effectively converge towards the fluorescent sheet and exit, improving light extraction efficiency. The extended surface extends horizontally and, after the fluorescent sheet is bonded to the LED chip, flatly covers the entire top surface of the LED chip. This causes the light from each edge area of ​​the LED chip to be uniformly concentrated towards the center, i.e., towards the fluorescent sheet, increasing the number of reflections of light before it exits the LED encapsulation structure and enhancing structural stability.

[0022] 8. In this embodiment of the invention, the encapsulating adhesive layer serves as a transition medium for light to propagate from the LED chip to the outside. A suitable refractive index can increase the efficiency of light reflection from the LED chip into the phosphor, reduce interface light loss, and improve light extraction efficiency. The height of the encapsulating adhesive layer relative to the substrate is consistent with the height of the phosphor, reducing light scattering and stray light. The LED encapsulation structure with consistent height ensures uniform stress during subsequent encapsulation reinforcement, guaranteeing consistency in mass production.

[0023] 9. In this embodiment of the invention, when the sum of the projected areas of the transparent adhesive and the phosphor sheet is greater than or equal to the top surface of the LED chip, the area of ​​the blue light emitted by the LED chip covered by the phosphor is increased, avoiding direct emission of unexcited blue light, improving spectral consistency. The tilted structure causes multiple reflections of the emitted light from the edge of the phosphor sheet, increasing the optical path and improving the phosphor excitation efficiency. Through the synergistic design of heat curing of the encapsulating adhesive layer and optimization of the projected area, the reflection efficiency and structural strength of the encapsulating adhesive layer are enhanced. The planar projected area of ​​the light-emitting surface based on the substrate is less than or equal to the planar projected area of ​​the LED chip. The central area of ​​the phosphor sheet directly above has the highest absorption and conversion efficiency for blue light, outputting more stable color-converted light, reducing the proportion of edge color-converted light, further improving spectral consistency, enhancing the directionality of light, and reducing floodlight interference.

[0024] 10. This embodiment of the invention also provides an LED packaging structure, which is formed by the LED packaging structure preparation method described above. The light-emitting surface of the phosphor sheet can make the light emitted by the LED chip more concentrated in the central area of ​​the entire LED packaging structure. A gap is provided between the encapsulating adhesive layer and the phosphor sheet. The gap can be formed between the four sides of the phosphor sheet and the encapsulating adhesive layer, or between the bottom surface of the phosphor sheet and the encapsulating adhesive layer. Transparent adhesive is placed in the gap to wrap and fix the phosphor sheet, fill the gap, reduce reflection loss at the interface, and improve luminous efficiency and uniformity. At the same time, the transparent adhesive layer can serve as a light diffusion pretreatment layer, so that the light emitted by the LED chip is first scattered and homogenized by the transparent adhesive layer, and then enters the white adhesive layer for further refraction into the phosphor sheet. The transparent adhesive layer can also buffer mechanical impact during the packaging process or use. Attached Figure Description

[0025] Figure 1 This is a flowchart of the method for preparing the LED packaging structure provided in the first embodiment of the present invention.

[0026] Figure 2 This is a side view of a schematic diagram of the dispensing process of the phosphor sheet assembly structure in the LED packaging structure preparation method provided in the first embodiment of the present invention.

[0027] Figure 3This is a top view illustrating the dispensing process of the phosphor sheet assembly structure in the LED packaging structure preparation method provided in the first embodiment of the present invention.

[0028] Figure 4 This is a side view of the phosphor assembly structure in the LED packaging structure preparation method provided in the first embodiment of the present invention.

[0029] Figure 5 This is a schematic diagram of the layout of the phosphor film assembly structure in the blue film in the LED packaging structure preparation method provided in the first embodiment of the present invention.

[0030] Figure 6 This is a side view of the LED packaging structure provided in the second embodiment of the present invention. Figure 1 .

[0031] Figure 7 This is a side view of the LED packaging structure provided in the second embodiment of the present invention. Figure 2 .

[0032] Figure 8 This is a side view of the LED packaging structure provided in the third embodiment of the present invention.

[0033] Explanation of reference numerals in the attached diagram: 100. LED packaging structure; 200. LED packaging structure; 1. Substrate; 2. LED chip; 3. Phosphor sheet; 4. Encapsulating adhesive layer; 5. Gap; 6. Transparent adhesive; 7. Eutectic bonding layer; 10. Phosphor sheet assembly structure; 11. Double-sided film; 12. Heat-resistant substrate; 13. Blue film; 21. Top surface; 31. Light-emitting surface; 32. Light-incident surface; 33. Side surface; 41. Inclined structure; 42. Extension surface; 51. First gap. Detailed Implementation

[0034] 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. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0035] In the embodiments provided by this invention, it should be understood that "B corresponding to A" means that B is associated with A, and B can be determined based on A. However, it should also be understood that determining B based on A does not mean determining B solely based on A; B can also be determined based on A and / or other information.

[0036] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the invention. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Those skilled in the art should also recognize that the embodiments described in the specification are optional embodiments, and the actions and modules involved are not necessarily essential to the invention.

[0037] In various embodiments of the present invention, it should be understood that the sequence number of each process does not necessarily imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0038] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this application. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, or they may sometimes be executed in reverse order, depending on the functions involved. It is particularly important to note that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0039] Please see Figure 1 The first embodiment of the present invention provides a method for preparing an LED packaging structure 100, the method comprising the following steps: Step S1: Provide fluorescent sheet 3, and edge encapsulate fluorescent sheet 3 to form fluorescent sheet assembly structure 10. Fluorescent sheet assembly structure 10 includes fluorescent sheet 3 and transparent adhesive 6 disposed on the side 33 of fluorescent sheet. An inclined structure 41 is formed between transparent adhesive 6 and the side 33 of fluorescent sheet 3. Step S2: Provide substrate 1, fix LED chip 2 on substrate 1, attach phosphor sheet assembly structure 10 to the top surface 21 of LED chip 2 away from substrate 1, wherein phosphor sheet 3 includes light emitting surface 31 away from LED chip 2. Step S3: Apply adhesive to form an encapsulating layer 4 around the phosphor assembly structure 10 and the LED chip 2. The encapsulating layer 4, the phosphor assembly structure 10, the LED chip 2 and the substrate 1 form an LED encapsulation structure 100.

[0040] Understandably, in the LED packaging structure 100, the phosphor sheet 3 is the core component for realizing light color conversion. In the traditional preparation of the phosphor sheet 3, after the phosphor sheet 3 is cut and shaped, it is directly assembled with the LED chip 2. The right-angled edge of the phosphor sheet 3 will cause the light to undergo total internal reflection on the side 33 of the phosphor sheet, instead of entering the interior of the phosphor sheet 3 for color conversion, resulting in a loss of light extraction efficiency. Furthermore, the unevenness of the edge light will cause dark corners or bright spots, affecting the light output quality.

[0041] The present invention provides a method for preparing an LED packaging structure 100. By pre-preparing a phosphor sheet assembly structure 10 with transparent adhesive 6, the optical performance is optimized, the structural protection is strengthened, and the process compatibility is improved. The optical optimization and structural strengthening of the edges are completed before the phosphor sheet 3 enters the assembly process, laying the foundation for efficient and stable production in the subsequent packaging stage.

[0042] Furthermore, the area of ​​the light-emitting surface 31 is reduced, and the equivalent light intensity density is increased. The planar projection area of ​​the light-emitting surface 31 based on the substrate 1 is less than or equal to the planar projection area of ​​the LED chip 2 based on the substrate 1, that is, the size of the phosphor sheet 3 is less than or equal to the chip size. The smaller light-emitting surface 31 of the phosphor sheet 3 can reduce the beam half-power angle, achieve precise light control, and produce a focusing gain effect.

[0043] Specifically, please refer to Figure 2 - Figure 4 In step S1, a fluorescent sheet 3 is provided, and the fluorescent sheet 3 is edge-encapsulated to form a fluorescent sheet assembly structure 10, including the following steps: Step S11, a double-sided film 11 is provided, and the fluorescent sheet 3 is arranged in an array on the double-sided film 11; Step S12, transparent adhesive 6 is applied to the four sides of the fluorescent sheet 3 and an inclined structure 41 is formed on the side 33 of the fluorescent sheet 3; Step S13, the transparent adhesive 6 is cut to form a single fluorescent sheet assembly structure 10.

[0044] Understandably, in step S11, the fluorescent sheet 3 can be arrayed on the double-sided film 11 using a die bonder and a machine vision system. The double-sided film 11 with a double-layer structure is selected, with the upper layer being the receiving layer to fix the fluorescent sheet 3, making the subsequent transfer process more convenient, reducing the risk of damage to the fluorescent sheet 3, and improving efficiency and significantly reducing labor costs.

[0045] Specifically, the arrangement accuracy of the fluorescent sheet 3 on the double-sided film 11 is ±10μm, and a high-precision die bonder with visual positioning is used to arrange them in a predetermined number and at predetermined intervals.

[0046] Furthermore, please refer to Figure 2 and Figure 3 In step S12, transparent adhesive 6 is applied to the four sides of the fluorescent sheet 3 using a piezoelectric valve spraying method. After standing for 15 minutes, the transparent adhesive 6 covers the four sides of the fluorescent sheet 3 and forms an inclined structure 41. The transparent adhesive 6 and the fluorescent sheet 3 form a fluorescent sheet combination structure 10.

[0047] Specifically, the angle range of the inclined structure 41 formed between the transparent adhesive 6 and the side surface 33 of the fluorescent sheet 3 is 5°-45°, and the transparent adhesive 6 also includes an extension surface 42 extending in the horizontal direction.

[0048] Understandably, the tilt angle allows the transparent adhesive 6 to form a sloping bond with the side 33 of the fluorescent sheet. Compared to the right-angled edge of the fluorescent sheet 3, the tilted structure 41 reduces the stress concentration coefficient and optimizes optical reflection and light extraction efficiency. The transparent adhesive 6 has an extension surface 42 extending in the horizontal direction. The extension surface 42 is flush with the upper surface of the double film 11. The surface roughness of the double film 11 ensures the flatness of the extension surface 42. At the same time, the extension surface 42 prevents the ultra-thin fluorescent sheet 3 from breaking during casting and transfer, and serves as a visual marker to provide a clear edge contrast during waterjet cutting and casting, ensuring assembly accuracy.

[0049] The extension surface 42 is naturally flowed from the transparent adhesive 6 to the surface of the double-sided film 11, and the extension surface 42 is tightly bonded to the support layer of the double-sided film 11.

[0050] Furthermore, combining Figure 4 and Figure 6 The length c of the extended surface 42 (e.g.) Figure 4 c) shown in the figure and the length a of the fluorescent sheet 3 (as shown in the figure) Figure 4 As shown in a), the length of LED chip 2 is b (as shown in the figure). Figure 6 As shown in b), 2c + a = b.

[0051] Understandably, the length b of LED chip 2 (e.g.) Figure 6 As shown in b), the design specifications of the LED chip are fixed. During the die bonding stage, a high-precision die bonder is used to centrally attach the phosphor sheet 3 to the top surface of the LED chip 2, ensuring that the distance between both sides of the phosphor sheet 3 and the edge of the LED chip 2 is c, that is, the length c of the extension surface 42 (as shown in the figure). Figure 4 As shown in c), both sides are equal, ensuring that the extension surface 42 exactly covers the edge areas of the LED chip 2 that are not covered by the phosphor sheet 3. The light emitted from different areas of the LED chip 2 is converted by the phosphor sheet 3 at the center and guided by the extension surface 42 at the edge, forming a cooperative propagation path in the encapsulation adhesive layer 4. This avoids light scattering or refraction disorder caused by size misalignment and improves the uniformity of light output.

[0052] Specifically, after the adhesive is applied and allowed to stand, an inclined structure 41 is formed between the transparent adhesive 6 and the side surface 33 of the fluorescent sheet 3 based on surface tension. The inclined structure 41 has an included angle A (e.g., ...). Figure 4 As shown in the figure, angle A (as shown in the figure) Figure 4 The angle range of A) shown is between 5° and 45°.

[0053] Understandably, the tilted structure 41 causes light that might otherwise be lost due to reflection or refraction at the edge of the encapsulating adhesive layer 4 to undergo a first reflection between different media before entering the phosphor sheet 3, thus enabling more light to effectively converge and exit the phosphor sheet 3 and improve light extraction efficiency.

[0054] The extension surface 42 extends horizontally and, after the phosphor sheet 3 is attached to the LED chip 2, flatly covers the top surface 21 of the entire LED chip 2, so that the light from each edge area of ​​the LED chip 2 is evenly concentrated towards the center, i.e. towards the phosphor sheet 3, increasing the number of reflections of light before it is emitted from the LED package structure 100, and enhancing the structural stability.

[0055] Furthermore, the angle range of the inclined structure 41 formed between the transparent adhesive 6 and the side 33 of the fluorescent sheet 3 is controlled by the amount of adhesive applied, which can be set by those skilled in the art as needed. The adhesive is applied by a needle with a diameter of 1 mm, and semi-enclosed adhesive is applied 0.1 mm from the edge of the fluorescent sheet 3.

[0056] Furthermore, the transparent adhesive 6 after dispensing needs to be pre-cured and shaped. As a non-limiting specific embodiment, in this invention, the transparent adhesive 6 can be cured by placing the fluorescent sheet 3 after dispensing into an oven and baking it to cure the transparent adhesive 6, wherein the baking conditions are 150°C / 1H.

[0057] Furthermore, in step S11, providing a double-sided film 11 and arranging the fluorescent sheet 3 in an array onto the double-sided film 11 includes the following steps for pre-processing the double-sided film 11: Step S111, providing a heat-resistant substrate 12 and attaching the double-sided film 11 including the fluorescent sheet 3 onto the heat-resistant substrate 12.

[0058] Understandably, the heat-resistant substrate 12 and the double-sided film 11 have a high temperature resistance of 150 degrees Celsius or higher. The pretreatment of attaching the double-sided film 11 with the fluorescent sheet 3 to the heat-resistant substrate 12 provides a rigid reference for the flexible double-sided film 11 and the fluorescent sheet 3, ensuring the physical support for subsequent processing with micron-level precision.

[0059] Specifically, a double-layer film 11 with a double-layer structure is selected. The lower layer is an adhesive layer, which is pasted onto the heat-resistant substrate 12 to prevent the double-layer film 11 from warping during subsequent processing and to ensure the accuracy of subsequent dispensing and cutting.

[0060] Further, in step S13, cutting the transparent adhesive 6 to form a single fluorescent sheet assembly structure 10 includes the following steps: step S131, cutting the transparent adhesive 6 with a water jet to form a single fluorescent sheet assembly structure 10; step S132, dehumidifying the cut fluorescent sheet assembly structure 10.

[0061] Understandably, the transparent adhesive 6 is water-jet cut based on the array coordinates of the fluorescent sheet 3 on the double-sided film 11. Water-jet cutting is a cold processing method. It cuts along the center line connecting adjacent fluorescent sheets 3, leaving a safety margin with the transparent adhesive 6, effectively protecting the optical properties of the fluorescent material.

[0062] In one non-limiting embodiment, the cut fluorescent sheet 3 can be placed in an oven for baking and dehumidification. The baking conditions are 100℃ / 1H to evaporate surface moisture and perform deep dehumidification, thereby reducing the water content of the fluorescent sheet 3.

[0063] Further, please refer to Figure 5 After cutting the transparent adhesive 6 in step S13 to form a single fluorescent sheet assembly structure 10, the process further includes step S14, providing a blue film 13, and casting the cut fluorescent sheet assembly structure 10 onto the blue film 13 in an array. The fluorescent sheet 3 includes a light-incident surface 32 near the LED chip 2, and the light-incident surface 32 is bonded to the blue film 13.

[0064] Understandably, the edges of the cut fluorescent sheet 3 are fragile. The blue film 13 has a slight adhesiveness and serves as a transition carrier, combining moisture-proof sealing and stress buffering functions to prevent displacement or detachment during handling. Traditional tape, due to its adhesiveness, is prone to chipping the edges of the fluorescent sheet 3 or scratching the light-incident surface 32 when peeled off. The molding process is completed by using the blue film 13, and fully automated equipment is used to achieve 180° rotation and precise bonding, so that the light-incident surface 32 is bonded to the blue film 13.

[0065] Further, in step S2, providing a substrate 1, fixing the LED chip 2 onto the substrate 1, and attaching the phosphor assembly structure 10 to the top surface 21 of the LED chip 2 on the side away from the substrate 1 includes the following steps: Step S21: Fix the LED chip 2 onto the substrate 1 by hot pressing eutectic bonding or reflow soldering eutectic bonding. Step S22: The phosphor sheet assembly structure 10 is attached to the top surface 21 of the LED chip 2 using die-bonding adhesive.

[0066] Understandably, eutectic bonding provides a low-resistance thermal path, ensuring the stability of the mechanical connection, optimizing optical matching, and improving luminous efficiency and consistency. The positioning accuracy of eutectic bonding and the visual alignment of die bonding ensure that the phosphor sheet 3 is precisely aligned with the top surface 21 of the LED chip 2, avoiding blue light leakage.

[0067] As a non-limiting specific embodiment, step S21 includes the following steps: placing the solder pad on the substrate 1, aligning the LED chip 2 with the solder pad, applying pressure and temperature with the hot press head to melt the solder pad to form an Au-Sn intermetallic compound, thereby completing the fixation of the LED chip 2 and the substrate 1.

[0068] Specifically, please refer to Figure 6 The fluorescent sheet 3 is attached to the top surface 21 of the LED chip 2 using adhesive film.

[0069] Furthermore, in step S22, attaching the phosphor assembly structure 10 to the top surface 21 of the LED chip 2 by die bonding adhesive also includes: step S221, applying adhesive to the surface of the LED chip 2, peeling the phosphor assembly structure 10 from the blue film 13 using a die bonding machine, and then transferring it to the top of the LED chip 2 to complete the bonding.

[0070] Understandably, the blue film 13 serves as a carrier platform for batch transfer, providing a physical protective barrier to buffer mechanical contact stress and prevent physical scratches during the process of the die bonder's nozzle picking up the phosphor sheet 3. The phosphor sheet 3 is arranged in an array on the blue film 13, which provides a batch positioning reference to maintain array accuracy. The nozzle of the die bonder peels the phosphor sheet 3 off the blue film 13 and then transfers it to the LED chip 2 to complete the bonding process. This automated operation improves production efficiency and reduces costs.

[0071] Further, after step S3, which involves applying adhesive to the periphery of the phosphor sheet 3 and the LED chip 2 to form the encapsulation layer 4, the following step is also included: step S4, which involves heating and curing the encapsulation structure.

[0072] Understandably, baking and curing can promote the cross-linking reaction of the encapsulating adhesive layer 4, forming a dense structure, improving the mechanical strength and sealing performance of the encapsulating adhesive layer 4, and preventing moisture and dust from entering.

[0073] As a non-limiting specific embodiment, the specific steps of heating and curing in step S4 include: baking: placing the phosphor sheet 3 and LED chip 2 wrapped by the encapsulating adhesive layer 4 into an oven and baking at 150°C for 2 hours to cure the encapsulating adhesive layer 4; cutting: based on the arrangement of the LED chip 2 on the substrate 1, using a water jet cutting method, cutting the substrate 1 with the LED chip 2 into independent single LED encapsulation structures 100 according to a preset size; baking: placing the cut single LED encapsulation structures 100 into an oven and baking at 100°C for 1 hour to perform dehumidification treatment.

[0074] Furthermore, the method for fabricating the LED packaging structure 100 provided in this invention also includes subsequent steps: Spectroscopy: The dehumidified single LED package structure 100 is placed into a spectrometer to detect its photoelectric parameters and the single light source is spectrally and color-sorted according to a preset standard; Packaging: The spectrally and color-sorted single LED package structure 100 is packaged by a tape and reel machine to complete the entire LED package structure 100 manufacturing process. In step S13, after the transparent adhesive 6 is cut to form the fluorescent sheet assembly structure 10, the extended surface 42 increases the contact area between the transparent adhesive 6 and the top surface 21 of the LED chip 2, thereby enhancing the overall bending strength.

[0075] Furthermore, the refractive index of the encapsulating adhesive layer 4 is between 1.40 and 1.55, and the height of the encapsulating adhesive layer 4 relative to the substrate 1 is equal to the height of the phosphor sheet 3 relative to the substrate 1.

[0076] Specifically, the transparent adhesive 6 is dispensed using a dispensing machine. The Z-axis height is controlled so that the height of the encapsulating adhesive layer 4 relative to the substrate 1 is equal to the height of the phosphor sheet 3 relative to the substrate 1, forming a flat surface. The height of the encapsulating adhesive layer 4 relative to the substrate 1 is controlled so that it does not exceed the height of the phosphor sheet 3 relative to the substrate 1, thus managing the propagation path of light inside the LED encapsulation structure 100, ensuring that the light interacts effectively with the phosphor sheet 3, improving light extraction efficiency, and forming a stable and compact LED encapsulation structure 100.

[0077] Furthermore, the sum of the planar projected area of ​​the transparent adhesive 6 and the planar projected area of ​​the fluorescent sheet 3 is greater than or equal to the planar projected area of ​​the top surface 21, and the planar projected area of ​​the light-emitting surface 31 based on the substrate 1 is less than or equal to the planar projected area of ​​the LED chip 2 based on the substrate 1.

[0078] Understandably, when the sum of the projected areas of the transparent adhesive 6 and the phosphor sheet 3 is greater than or equal to the top surface 21 of the LED chip 2, the area covered by the phosphor for the blue light emitted by the LED chip 2 is increased, preventing unexcited blue light from being emitted directly. The tilted structure 41 causes the emitted light from the edge of the phosphor sheet to undergo multiple reflections, increasing the optical path and improving the phosphor excitation efficiency. The smaller phosphor sheet 3 makes the light emitted by the LED chip 2 more concentrated in the central area of ​​the entire LED packaging structure 100, resulting in a smaller light-emitting surface 31. The light excited by the larger LED chip 2 is focused onto the smaller phosphor sheet 3 for emission. The larger LED chip 2 is more resistant to current, and the smaller phosphor sheet's light-emitting surface 31 more efficiently excites the phosphor sheet 3 to emit white light, precisely controlling the light, reducing the scattering loss of the phosphor sheet 3, and optimizing the light emission angle.

[0079] Please see Figure 6 - Figure 7 The second embodiment of the present invention provides an LED packaging structure 100, which is formed by the preparation method of the LED packaging structure 100 in the first embodiment.

[0080] LED packaging structure 100 includes a substrate 1, an LED chip 2 electrically connected to the substrate 1, and a phosphor sheet 3 disposed on the side of the LED chip 2 away from the substrate 1. The phosphor sheet 3 has a light-emitting surface 31 on the side away from the LED chip 2. The LED packaging structure 100 also includes an encapsulating adhesive layer 4 disposed around the side surface 33 of the LED chip 2 and the phosphor sheet 3. A gap 5 is provided between the encapsulating adhesive layer 4 and the phosphor sheet 3, and a transparent adhesive 6 is disposed in the gap 5.

[0081] Understandably, the main function of the phosphor 3 is to absorb the blue light emitted by the LED chip 2. Taking gallium nitride-based LED as an example, the gallium nitride-based LED chip 2 emits blue light, and the phosphor 3 converts the emitted blue light into other colors of light, such as yellow light. The yellow light and blue light are mixed to form white light, thereby realizing the emission of white light.

[0082] The encapsulating adhesive layer 4 has a specific refractive index and reflectivity. The refractive index is between that of the chip and the external environment. The light emitted by the LED chip 2 is directed from inside the chip to the encapsulating adhesive layer 4. The encapsulating adhesive layer 4 can refract the light into the external medium and reflect the light into the phosphor sheet 3 located on the side away from the substrate 1, making the light emission distribution more uniform and reducing the scattering and interference of light at the interface of different media.

[0083] Specifically, in this embodiment, the light-emitting surface 31 of the LED packaging structure 100 has a planar projected area based on the substrate 1 that is smaller than the planar projected area of ​​the LED chip 2 based on the substrate 1.

[0084] Specifically, according to the law of conservation of optical energy, the area of ​​the light-emitting surface 31 is reduced, and the equivalent light intensity density is increased. The planar projection area of ​​the light-emitting surface 31 based on the substrate 1 is smaller than the planar projection area of ​​the LED chip 2 based on the substrate 1, that is, the light-emitting surface 31 is reduced. The reduction of the light-emitting surface 31 directly leads to a reduction in the half-power angle of the beam, which can achieve more precise light pattern control and produce a focusing gain effect.

[0085] The light-emitting surface 31 only covers the high-brightness area in the center of the LED chip 2 to avoid uneven light color caused by low-efficiency excitation at the edge. The current density at the edge of the chip is high, which can easily cause wavelength shift. A gap 5 is set between the encapsulating adhesive layer 4 and the phosphor sheet 3. The gap 5 is filled with transparent adhesive 6. The transparent adhesive 6 can filter the edge blue light generated by the LED chip 2, so that more edge blue light gathers to the center of the phosphor sheet 3, optimizes color difference and suppresses edge light.

[0086] Specifically, the LED chip 2 includes a top surface 21 facing the phosphor sheet 3.

[0087] As an encapsulation material, transparent adhesive 6 can also buffer the stress difference between different material interfaces. The part of the top surface 21 of the LED chip 2 that is not covered by the encapsulation adhesive layer 4 is filled with transparent adhesive 6 to enhance structural stability.

[0088] The LED packaging structure 100 provided in the second embodiment of the present invention enhances the optical focusing effect by making spatial choices between the LED chip 2 and the phosphor sheet 3 inside the structure, thereby achieving a performance breakthrough in specific scenarios. It exchanges the reduction of the area of ​​the light-emitting surface 31 for the control precision of brightness and uniformity, and accurately controls the light field.

[0089] Furthermore, the fluorescent sheet 3 includes four fluorescent sheet side surfaces 33 adjacent to the light-emitting surface 31, and the gap 5 includes a first gap 51 between the encapsulating adhesive layer 4 and the fluorescent sheet side surfaces 33. A transparent adhesive 6 is disposed in the first gap 51, and an inclined structure 41 is formed between the encapsulating adhesive layer 4 and the sidewall of the transparent adhesive 6 disposed in the first gap 51.

[0090] Understandably, the transparent adhesive 6 fills the first gap 51 between the encapsulating adhesive layer 4 and the side 33 of the phosphor sheet, reducing the total internal reflection loss caused by air. The encapsulating adhesive layer 4 has a specific refractive index and reflectivity, which can increase the reflection of light at the interface between the encapsulating adhesive layer 4 and the external environment, improve the emission efficiency of light to the phosphor sheet 3, and help the phosphor sheet 3 convert more blue light.

[0091] Furthermore, the inclined structure 41 can also be formed between the transparent adhesive 6 and the side surface 33 of the fluorescent sheet. The essence of the inclined structure 41 is to provide a non-perpendicular transition surface when the two media come into contact and transition. The transparent adhesive 6 fills the first gap 51 between the encapsulation adhesive layer 4 and the side surface 33 of the fluorescent sheet. The constraint conditions of different interfaces can allow the transparent adhesive 6 to form an inclined transition surface.

[0092] When light enters from one medium to another, part of the light is reflected at the interface between the two media, and the other part enters the second medium and is refracted. An inclined structure 41 is formed between the sidewall of the encapsulating adhesive layer 4 and the transparent adhesive 6, which increases the number of reflections or refractions and the emission path of light in the LED encapsulation structure 100, and improves the excitation efficiency of the phosphor sheet 3. The encapsulating adhesive layer 4 is set around the sidewall 33 of the LED chip 2 and the phosphor sheet 3, and is directly attached to the sidewall of the LED chip 2, which enhances the structural support, improves the optical uniformity, and helps the LED chip 2 to dissipate heat and improve thermal stability.

[0093] For example, such as Figure 6As shown, taking a beam of light emitted from the area of ​​the top surface 21 of the LED chip 2 that is not covered by the phosphor sheet 3, and forming a 30° angle with the central axis of the LED packaging structure 100 as an example, its propagation path in the LED packaging structure 100 is as follows: The beam of light is directed at the transparent adhesive 6 at a 30° angle, and within the transparent adhesive 6, it maintains the original path and is directed at the interface between the transparent adhesive 6 and the encapsulation adhesive layer 4. According to the laws of refraction and reflection, the beam of light is refracted and reflected at the interface. The reflected beam is deflected towards the central region of the phosphor sheet 3 based on the law of reflection and enters the phosphor sheet 3. The refracted beam enters the encapsulation adhesive layer 4 and is reflected again at the interface between the encapsulation adhesive layer 4 and the external environment. The reflected beam that is reflected for the second time is also deflected towards the central region of the phosphor sheet 3 based on the law of reflection and enters the phosphor sheet 3.

[0094] The transparent adhesive 6, being fluid before assembly, is pre-attached to the four sides 33 of the phosphor sheet 3. The fluidity of the transparent adhesive 6 helps ensure precise alignment between the phosphor sheet 3 and the LED chip 2, meeting high-precision assembly requirements. Simultaneously, heat generated in the area of ​​the top surface 21 of the LED chip 2 not covered by the phosphor sheet 3 can be directly transferred through the transparent adhesive 6, reducing the temperature of the LED chip 2.

[0095] Optionally, high-refractive-index nanoparticles can be added to the transparent adhesive 6 to enhance the refraction efficiency of light inside the LED packaging structure 100. Alternatively, an optical waveguide structure can be embedded in the transparent adhesive 6 to increase the luminous flux per unit area and improve the coupling efficiency of the phosphor sheet 3.

[0096] Furthermore, the inclined structure 41 is a curved surface protruding toward the central axis of the LED package structure 100, the LED chip 2 includes a top surface 21 facing the phosphor sheet 3, and the inclined structure 41 extends along the edge of the top surface 21.

[0097] Understandably, the inclined structure 41 extends along the edge of the top surface 21 of the LED chip 2 to ensure that the matching between the phosphor sheet 3 and the transparent adhesive 6 can completely cover the top surface 21 of the LED chip 2, enhance the tightness of the bond between the phosphor sheet 3 and the top surface 21, improve structural stability, make the contact between the phosphor sheet 3 and the chip more uniform and stable, reduce structural deformation and cracking caused by stress concentration or poor local contact, guide and control the propagation path of light, so that the light can be distributed and propagated more uniformly, and reduce the loss of light reflection and scattering.

[0098] Specifically, the extension length of the inclined structure 41 on the top surface 21 is adapted to match the edge length of the top surface 21 to supplement the coverage of the transparent adhesive 6 on the top surface 21. The planar projection area of ​​the transparent adhesive 6 relative to the substrate within the first gap 51 is adapted to the area of ​​the top surface 21 not covered by the transparent adhesive 6, thereby achieving the edge light leakage suppression effect and enhancing structural strength compensation.

[0099] Specifically, the curved shape of the inclined structure 41 protruding towards the central axis of the LED packaging structure 100 can guide and converge the blue light emitted from the edge of the top surface 21 of the LED chip 2 towards the center, so that the light enters the phosphor 3 more concentratedly, improves the absorption efficiency of the phosphor 3 for blue light, and thus enhances the intensity of the yellow light emitted by the phosphor 3, which is conducive to forming a more uniform and brighter white light.

[0100] Furthermore, the inclined structure 41 forms an angle A with the side surface 33 of the fluorescent sheet (as shown in Figure 7), and the angle A (as shown in Figure 7) ranges from 5° to 45°.

[0101] Understandably, a properly set angle allows the tilted structure 41 to match the optical characteristics of the LED chip 2 and the phosphor 3, including refractive index and reflectivity. When light travels from the LED chip 2 to the tilted structure 41, a suitable angle A (such as...) is required. Figure 7 Angle A) shown in the figure can reduce the refraction loss of light at the interface, allowing more light to enter the phosphor 3 smoothly and participate in the light conversion process, which is beneficial for the yellow light emitted by the phosphor 3 to be emitted to the outside better.

[0102] Furthermore, the distance H1 between the upper surface of the encapsulating adhesive layer 4 and the substrate 1 (e.g., Figure 7 The distance H1 shown is less than or equal to the distance H2 between the upper surface of the phosphor sheet 3 and the substrate 1 (e.g., H1). Figure 7 H2 as shown in the figure.

[0103] Understandably, controlling the height of the encapsulating adhesive layer 4 relative to the substrate 1, so that it does not exceed the height of the phosphor sheet 3 relative to the substrate 1, manages the propagation path of light inside the encapsulation structure, ensures that the light interacts effectively with the phosphor sheet 3, improves light extraction efficiency, and forms a stable and compact encapsulation structure.

[0104] Furthermore, the LED packaging structure 100 also includes a eutectic bonding layer 7 disposed between the LED chip 2 and the substrate 1, so as to fix the LED chip 2 and the substrate 1 with the eutectic bonding layer 7.

[0105] Specifically, the eutectic bonding layer 7 can be a gold-tin alloy layer. The LED packaging structure 100 provided by the present invention adopts gold-tin eutectic bonding. Gold-tin eutectic bonding is a mature microelectronic manufacturing process in high-power devices, with high process stability and reliability.

[0106] Furthermore, the distance H3 between the upper surface of the transparent adhesive 6 disposed within the first gap 51 and the substrate 1 (e.g., ...) Figure 7 H3 as shown is less than or equal to the distance H1 between the upper surface of the encapsulating adhesive layer 4 and the substrate 1 (e.g., H3). Figure 7 H1 as shown in the figure.

[0107] Specifically, the upper surface of the transparent adhesive 6 disposed in the first gap 51 can be on the same plane as the upper surface of the encapsulating adhesive layer 4, which helps to make the upper surface of the LED encapsulation structure 200 flat, facilitating subsequent encapsulation process and integration with other components; or it can be lower than the upper surface of the encapsulating adhesive layer 4, so that the light emitted through the upper surface of the transparent adhesive 6 layer in the first gap 51 may re-enter the encapsulating adhesive layer 4, and thus be reflected again in the encapsulating adhesive layer 4, thereby giving the light more possible paths to enter the phosphor sheet 3 for conversion.

[0108] Specifically, the inclined structure 41 forms an angle with the side 33 of the fluorescent sheet, and at this time the transparent adhesive 6 cannot be exposed through the upper surface of the encapsulating adhesive layer 4.

[0109] Specifically, as a non-restrictive, feasible solution, such as Figure 7 As shown, in the LED packaging structure 100 provided in this embodiment, the distance H1 between the upper surface of the encapsulating adhesive layer 4 and the substrate 1 (e.g., ...) Figure 7 H1 shown is equal to the distance H2 between the upper surface of the phosphor 3 and the substrate 1 (as shown in the figure). Figure 7 H2 as shown, the distance H3 between the upper surface of the transparent adhesive 6 disposed within the first gap 51 and the substrate 1 (as shown in the figure) Figure 7 H3 as shown is equal to the distance H1 between the upper surface of the encapsulating adhesive layer 4 and the substrate 1 (e.g., ...). Figure 7 H1 as shown in the figure.

[0110] The three components are equidistant from the substrate, meaning their upper surfaces are flush, forming a flat light-emitting surface. When light is emitted from the LED packaging structure 100, it only needs to pass through the interface between the encapsulating adhesive layer and the air or the interface between the phosphor sheet and the air. The flush surface allows the light to be emitted at a more perpendicular angle, reducing reflection loss and minimizing multiple refractions or total internal reflections caused by the unevenness of the overall upper surface of the LED packaging structure 100. This also enhances packaging reliability and reduces stress damage.

[0111] Furthermore, the phosphor sheet 3 is a phosphor sheet including yellow phosphor, and the LED chip 2 is a blue LED chip 2. The phosphor is used to absorb the blue light emitted by the LED chip 2 and emit yellow light, and the blue light and yellow light mix to form white light.

[0112] Specifically, in one non-limiting possible implementation, a blue LED chip 2, such as an InGaN-based semiconductor, is used. The emission wavelength of the LED chip 2 is mainly in the blue light band of 450-470nm. After the LED chip 2 is powered on, it releases energy through the recombination of electrons and holes to generate blue photons. A phosphor sheet 3 is made by mixing a phosphor such as YAG:Ce³⁺ yttrium aluminum garnet with a matrix material such as resin. The phosphor sheet 3 efficiently absorbs blue light. When blue photons are incident on the phosphor sheet 3, they are absorbed by the phosphor particles. After absorbing energy, the phosphor sheet 3 can emit light of other wavelengths, such as yellow light and red light, from the light-emitting surface 31. The blue light that is not absorbed by the phosphor mixes with the yellow light emitted by the phosphor in space to form white light.

[0113] Furthermore, please refer to Figure 8 The third embodiment of the present invention provides an LED packaging structure 200. The LED packaging structure 200 differs from the LED packaging structure 100 provided in the second embodiment only in that the planar projection area of ​​the light-emitting surface 31 based on the substrate 1 is equal to the planar projection area of ​​the LED chip 2 based on the substrate 1.

[0114] Compared with the prior art, the LED packaging structure preparation method and LED packaging structure provided by the present invention have the following beneficial effects: 1. The present invention provides a method for preparing an LED packaging structure. The edge of the phosphor sheet is a weak area. A phosphor sheet assembly structure is prepared in advance to strengthen the physical protection of the phosphor sheet. The tilted structure changes the light emission angle at the edge of the phosphor sheet, avoiding total internal reflection at the right-angle edge and improving light extraction efficiency. The encapsulating adhesive layer reflects the light emitted from the side of the LED chip to the light-emitting surface. The smaller area of ​​the phosphor sheet can concentrate the light emitted by the LED chip in the central area of ​​the entire LED packaging structure to obtain a smaller light-emitting surface. The light excited by the larger LED chip is focused and emitted from the smaller area of ​​the phosphor sheet. The large LED chip is more resistant to current. Reducing the light-emitting surface of the phosphor sheet makes it more concentrated and efficient to excite the phosphor sheet to emit white light, accurately control the light, reduce the scattering loss of the phosphor sheet, and optimize the light emission angle. The transparent adhesive wraps the right-angle edge of the phosphor sheet to form a phosphor sheet assembly structure, which provides a guiding path for the subsequent encapsulating adhesive layer dispensing process, so that the encapsulating adhesive layer covers the gap between the phosphor sheet and the chip more evenly and reduces bubbles or voids.

[0115] 2. In this embodiment of the invention, a fluorescent sheet assembly structure is pre-prepared. The fluorescent sheets are fixed by adhesive bonding on the upper and lower surfaces of the double-sided film to avoid positional shifts during array arrangement. Multiple fluorescent sheets are fixed in an array, facilitating batch processing. The inclined structure formed between the transparent adhesive and the side of the fluorescent sheet changes the emission angle of light on the side of the fluorescent sheet, reducing total internal reflection loss, improving luminous efficiency, and reducing the dark angle of the light spot. The transparent adhesive is tightly bonded to the edge of the fluorescent sheet, reducing reflection loss at the interface and improving luminous efficiency and uniformity. At the same time, the transparent adhesive can serve as a light diffusion pretreatment layer, so that some of the light emitted from the top surface of the LED chip is first scattered and homogenized by the transparent adhesive before entering the encapsulation adhesive layer for reflection. The reflected light enters the fluorescent sheet for light conversion. The transparent adhesive is cut to form a single fluorescent sheet assembly structure. Based on the fluorescent sheets fixed by the double-sided film array, the transparent adhesive is cut by water jet cutting to achieve batch segmentation, remove burrs, and ensure that the size tolerance of each individual sheet is controlled within a preset accuracy range, meeting the requirements of LED packaging structure for the uniformity of fluorescent sheet size.

[0116] 3. In this embodiment of the invention, the curing of the transparent adhesive usually requires high-temperature treatment. The heat resistance temperature of the double-sided film is greater than or equal to 150 degrees Celsius. However, the double-sided film may soften during the heating process. The double-sided film is pasted onto the heat-resistant substrate to prevent the array of fluorescent film from shifting during the heating process of the double-sided film, thus avoiding affecting the subsequent cutting accuracy. At the same time, the heat-resistant substrate can conduct heat released by the transparent adhesive during the heating and curing process, avoiding the deterioration of the fluorescent film caused by local overheating.

[0117] 4. In this embodiment of the invention, the prefabrication of the fluorescent sheet assembly structure also includes cutting and dehumidification steps. Water jet cutting is used to complete the precision processing without heat damage, ensuring the uniformity of the fluorescent sheet size. The cut surface formed by water jet cutting is free of burrs and melt layer, avoiding the micro-cracks of traditional mechanical cutting and reducing the risk of stress concentration during subsequent encapsulation. Dehumidification treatment can prevent the phosphor from deliquescing, improve the tensile strength of the transparent adhesive, and ensure the quality of the transparent adhesive curing.

[0118] 5. In this embodiment of the invention, the blue film is a silicone-based thermosetting protective film. After the phosphor sheet assembly structure is prefabricated, the phosphor sheet assembly structure is pasted onto the LED chip during the processing flow. The blue film provides adhesion and reduces the edge collapse rate of the phosphor sheet during casting and transfer.

[0119] 6. In this embodiment of the invention, the LED chip is fixed to the substrate by hot-pressing eutectic bonding or reflow soldering eutectic bonding. The phosphor assembly structure is attached to the top surface of the LED chip by die bonding adhesive, thus completing the fixation of the LED chip to the substrate and the attachment of the LED chip to the phosphor assembly structure. Hot-pressing eutectic bonding and reflow soldering eutectic bonding of the LED chip are both eutectic bonding processes. Eutectic bonding uses the metallurgical bonding of intermetallic compounds to build a low-resistance heat conduction path and a stable electrical connection, reducing the chip junction temperature and ensuring electrical stability. The die bonding adhesive process precisely controls the position and adhesive layer thickness of the phosphor assembly structure attached to the LED chip. Combined with the high-precision positioning of eutectic bonding, precise matching is achieved, ensuring the consistency of luminous efficacy and spectrum. At the same time, eutectic bonding and die bonding adhesive processes are compatible with various substrate materials such as ceramics and metals, ensuring high performance while having cost advantages for mass production.

[0120] 7. In this embodiment of the invention, the inclined structure formed by the transparent adhesive and the side of the fluorescent sheet allows light that might otherwise be lost due to reflection or refraction at the edge of the encapsulation adhesive layer to undergo a first reflection between different media before entering the fluorescent sheet. This allows more light to effectively converge towards the fluorescent sheet and exit, improving light extraction efficiency. The extended surface extends horizontally and, after the fluorescent sheet is bonded to the LED chip, flatly covers the entire top surface of the LED chip. This causes the light from each edge area of ​​the LED chip to be uniformly concentrated towards the center, i.e., towards the fluorescent sheet, increasing the number of reflections of light before it exits the LED encapsulation structure and enhancing structural stability.

[0121] 8. In this embodiment of the invention, the encapsulating adhesive layer serves as a transition medium for light to propagate from the LED chip to the outside. A suitable refractive index can increase the efficiency of light reflection from the LED chip into the phosphor, reduce interface light loss, and improve light extraction efficiency. The height of the encapsulating adhesive layer relative to the substrate is consistent with the height of the phosphor, reducing light scattering and stray light. The LED encapsulation structure with consistent height ensures uniform stress during subsequent encapsulation reinforcement, guaranteeing consistency in mass production.

[0122] 9. In this embodiment of the invention, when the sum of the projected areas of the transparent adhesive and the phosphor sheet is greater than or equal to the top surface of the LED chip, the area of ​​the blue light emitted by the LED chip covered by the phosphor is increased, avoiding direct emission of unexcited blue light, improving spectral consistency. The tilted structure causes multiple reflections of the emitted light from the edge of the phosphor sheet, increasing the optical path and improving the phosphor excitation efficiency. Through the synergistic design of heat curing of the encapsulating adhesive layer and optimization of the projected area, the reflection efficiency and structural strength of the encapsulating adhesive layer are enhanced. The planar projected area of ​​the light-emitting surface based on the substrate is less than or equal to the planar projected area of ​​the LED chip. The central area of ​​the phosphor sheet directly above has the highest absorption and conversion efficiency for blue light, outputting more stable color-converted light, reducing the proportion of edge color-converted light, further improving spectral consistency, enhancing the directionality of light, and reducing floodlight interference.

[0123] 10. This embodiment of the invention also provides an LED packaging structure, which is formed by the LED packaging structure preparation method described above. The light-emitting surface of the phosphor sheet can make the light emitted by the LED chip more concentrated in the central area of ​​the entire LED packaging structure. A gap is provided between the encapsulating adhesive layer and the phosphor sheet. The gap can be formed between the four sides of the phosphor sheet and the encapsulating adhesive layer, or between the bottom surface of the phosphor sheet and the encapsulating adhesive layer. Transparent adhesive is placed in the gap to wrap and fix the phosphor sheet, fill the gap, reduce reflection loss at the interface, and improve luminous efficiency and uniformity. At the same time, the transparent adhesive layer can serve as a light diffusion pretreatment layer, so that the light emitted by the LED chip is first scattered and homogenized by the transparent adhesive layer, and then enters the white adhesive layer for further refraction into the phosphor sheet. The transparent adhesive layer can also buffer mechanical impact during the packaging process or use.

[0124] The foregoing has provided a detailed description of the preparation method and the LED packaging structure disclosed in the embodiments of the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are 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. Any modifications, equivalent substitutions, and improvements made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an LED packaging structure, characterized in that: The preparation method includes the following steps: A fluorescent sheet is provided, and the fluorescent sheet is edge-encapsulated to form a fluorescent sheet assembly structure. The fluorescent sheet assembly structure includes the fluorescent sheet and a transparent adhesive disposed on the side of the fluorescent sheet, and the transparent adhesive and the side of the fluorescent sheet form an inclined structure. A substrate is provided, an LED chip is fixed on the substrate, and a phosphor sheet assembly structure is attached to the top surface of the LED chip on the side away from the substrate, wherein the phosphor sheet includes a light-emitting surface on the side away from the LED chip; An encapsulating adhesive layer is formed by applying adhesive around the phosphor assembly structure and the LED chip. The encapsulating adhesive layer, the phosphor assembly structure, the LED chip, and the substrate form the LED encapsulation structure.

2. The method for preparing the LED packaging structure as described in claim 1, characterized in that: A fluorescent sheet is provided, and the fluorescent sheet is edge-encapsulated to form a fluorescent sheet assembly structure. The fluorescent sheet assembly structure includes the fluorescent sheet and a transparent adhesive disposed on the side of the fluorescent sheet. The transparent adhesive and the side of the fluorescent sheet form an inclined structure. The method includes the following steps: A double-sided film is provided, and the fluorescent sheet is arranged in an array on the double-sided film; Apply transparent adhesive to the four sides of the fluorescent sheet and form the inclined structure on the sides of the fluorescent sheet; The transparent adhesive is cut to form individual fluorescent sheet assembly structures.

3. The method for preparing the LED packaging structure as described in claim 2, characterized in that: Providing a double-sided film, and arranging the fluorescent sheets in an array onto the double-sided film includes the following steps: A heat-resistant substrate is provided, and the double-sided film including the fluorescent sheet is adhered to the heat-resistant substrate.

4. The method for preparing the LED packaging structure as described in claim 2, characterized in that: Cutting the transparent adhesive to form a single fluorescent sheet assembly structure includes the following steps: The transparent adhesive is cut using a water jet to form individual fluorescent sheet assembly structures; The cut fluorescent sheet assembly structure is then dehumidified.

5. The method for preparing the LED packaging structure as described in claim 2, characterized in that: After cutting the transparent adhesive to form a single fluorescent sheet assembly structure, the process further includes: A blue film is provided, and the cut phosphor sheet assembly structure is arranged in an array and cast onto the blue film. The phosphor sheet includes a light-incident surface near the LED chip, and the light-incident surface is bonded to the blue film.

6. The method for preparing the LED packaging structure as described in claim 1, characterized in that: Providing a substrate, fixing an LED chip onto the substrate, and attaching the phosphor assembly structure to the top surface of the LED chip on the side away from the substrate includes the following steps: The LED chip is fixed to the substrate by hot-pressing eutectic bonding or reflow soldering eutectic bonding. The phosphor assembly structure is attached to the top surface of the LED chip using die-bonding adhesive.

7. The method for preparing the LED packaging structure as described in claim 1, characterized in that: The angle between the transparent adhesive and the side of the fluorescent sheet forming the inclined structure ranges from 5° to 45°, and the transparent adhesive also includes an extension surface extending in the horizontal direction.

8. The method for preparing the LED packaging structure as described in claim 1, characterized in that: The refractive index of the encapsulating adhesive layer is between 1.40 and 1.55, and the height of the encapsulating adhesive layer relative to the substrate is equal to the height of the phosphor sheet relative to the substrate.

9. The method for preparing the LED packaging structure as described in claim 8, characterized in that: The sum of the planar projected area of ​​the transparent adhesive and the planar projected area of ​​the fluorescent sheet is greater than or equal to the planar projected area of ​​the top surface, and the planar projected area of ​​the light-emitting surface based on the substrate is less than or equal to the planar projected area of ​​the LED chip based on the substrate.

10. An LED packaging structure, characterized in that: The device includes a substrate, an LED chip electrically connected to the substrate, and a phosphor sheet disposed on the side of the LED chip away from the substrate, wherein the side of the phosphor sheet facing away from the LED chip is the light-emitting surface. The LED packaging structure further includes an encapsulating adhesive layer surrounding the LED chip and the phosphor sheet, with a gap between the encapsulating adhesive layer and the phosphor sheet, and transparent adhesive disposed within the gap.

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