LED packaging structure, LED backlight module and preparation method of LED backlight module

Abstract

The application relates to the technical field of LED packaging, and discloses an LED packaging structure, an LED backlight module and a preparation method of the LED backlight module. The LED packaging structure comprises an LED chip, a fluorescent glue film and a protective glue film, the fluorescent glue film covers the side surface and the upper surface of the LED chip, the protective glue film covers the side surface and the upper surface of the fluorescent glue film, the fluorescent glue film is obtained by mixing a silica gel base material and fluorescent powder and then solidifying, and the protective glue film is obtained by solidifying the silica gel base material of the fluorescent glue film. By implementing the application, the luminous brightness of the LED packaging structure can be improved, the light-emitting angle of the LED chip can be enlarged, water vapor is prevented from contacting the LED chip, the concentration and the light-emitting uniformity of the LED backlight module are improved, and therefore the light-emitting uniformity and the reliability of the LED packaging structure and the backlight module are improved.

Description

Technical Field

[0001] This invention relates to the technical field of LEDs, and more particularly to an LED packaging structure, an LED backlight module, and a method for manufacturing the LED backlight module. Background Technology

[0002] LEDs and LED modules, due to their advantages such as low energy consumption, long lifespan, and fast response speed, have been widely used in various fields such as display backlights. The core structure of a conventional LED and module consists of a bracket 10, an LED chip 1, and a phosphor film 2. The phosphor film 2 is a mixture of phosphor uniformly dispersed in silicone. During the encapsulation process, the phosphor film 2 is applied to the surface of the LED chip 1 using a dispensing method, resulting in the LED encapsulation structure, as shown below. Figure 1 As shown.

[0003] However, when applying the aforementioned conventional LEDs and modules to display backlight scenarios, the adhesive-based encapsulation method leads to large dispersion in the luminous performance of the LEDs and modules, low product concentration, and reduced yield in mass production. Simultaneously, the large distance between most of the phosphor and the LED chip 1 results in low phosphor excitation and limited photon conversion efficiency, ultimately causing low LED brightness. Furthermore, the phosphor near the LED surface is directly exposed to the external environment, making it easy for moisture to penetrate and contact the LED chip 1, thus degrading the performance of the LED and module. In addition, traditional backlight modules typically consist of a substrate 4, an LED encapsulation structure, a lens 8, and a diffuser 9. Conventional LED chips 1 are single-sided emission, with a light intensity distribution that is strong in the center and weak around the edges, resulting in a small inherent emission angle. Display backlights require uniform and wide illumination coverage. To compensate for the insufficient emission angle, a lens 8 and a diffuser 9 must be additionally mounted outside the LED. The emission angle is widened by refraction through the lens 8, forming an LED backlight module as shown in the image. Figure 2 As shown, this additional design not only increases the structural complexity and manufacturing cost of the backlight, but may also lead to a decrease in illumination uniformity due to lens 8 assembly deviation, thus affecting the display effect of the screen. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an LED packaging structure, an LED backlight module and a method for preparing the LED backlight module, which has high luminous brightness and high concentration, expands the light emission angle of the LED chip, blocks water vapor from contacting the LED chip, and effectively improves the light emission uniformity and reliability of the LED packaging structure and the backlight module.

[0005] To solve the above-mentioned technical problems, the first aspect of the present invention provides an LED packaging structure, including: an LED chip, a fluorescent film, and a protective film, wherein the fluorescent film covers the side surface and the top surface of the LED chip, and the protective film covers the side surface and the top surface of the fluorescent film;

[0006] The fluorescent film is obtained by mixing and curing a silicone base material and fluorescent powder.

[0007] The protective film is obtained by curing the silicone base material of the fluorescent film.

[0008] As an improvement to the above solution, the ratio of the thickness of the fluorescent adhesive film to the thickness of the LED chip is (0.25-1.25):1; the ratio of the thickness of the protective adhesive film to the thickness of the fluorescent adhesive film is (0.3-3):1.

[0009] As an improvement to the above scheme, the raw materials for preparing the silicone base material include polydimethylsiloxane, crosslinking agent, catalyst and inhibitor. The silicone base material can be cured in stages. The first curing temperature of the silicone base material is 80℃-100℃, and the second curing temperature of the silicone base material is 120℃-150℃.

[0010] As an improvement to the above scheme, the polydimethylsiloxane is a vinyl-terminated polydimethylsiloxane, the crosslinking agent is a polysiloxane containing Si-H groups, and the molar ratio of the Si-H groups to the vinyl group is (1.2-2):1;

[0011] The concentration of the catalyst added to the silica gel base is 10ppm-200ppm;

[0012] The molar ratio of the inhibitor to the catalyst is (0.5-10):1.

[0013] The catalyst is a platinum complex;

[0014] The inhibitor is at least one of ethynylcyclohexanol, methylbutynol, 3-methyl-1-dodecyn-3-ol, and tetramethyltetravinylcyclotetrasiloxane.

[0015] As an improvement to the above solution, an adhesive layer is further provided between the fluorescent film and the LED chip, and the adhesive layer is obtained by curing the silicone base material in the fluorescent film;

[0016] The thickness of the adhesive layer is 5μm-20μm.

[0017] A second aspect of the present invention provides an LED backlight module, including a substrate and the LED packaging structure, wherein the LED packaging structure is arranged in an array on the substrate.

[0018] A third aspect of the present invention provides a method for manufacturing the aforementioned LED backlight module, comprising the following steps:

[0019] A mold is provided, and a fluorescent adhesive obtained by mixing silicone base material and phosphor is initially cured in the mold to obtain a fluorescent adhesive film. The fluorescent adhesive film is then cut to obtain a single fluorescent adhesive film in the shape of a cross.

[0020] The silicone base material is initially cured in the mold to obtain a protective film. The protective film is then cut to obtain single protective films in the shape of a cross.

[0021] A substrate is provided, on which LED chips are fixed and arranged in an array;

[0022] A single fluorescent adhesive film is placed on the upper surface of an LED chip, and a plastic film is used to cover the sides and upper surface of the LED chip, and then completely cured and molded.

[0023] A single protective film is placed on the upper surface of the fluorescent film, and a plastic film is used to cover the sides and upper surface of the fluorescent film with the single protective film, and then completely cured and formed.

[0024] As an improvement to the above solution, the initial curing temperature of the silicone base material is 80℃-100℃, and the curing time is 3min-10min;

[0025] The complete curing temperature of the silicone base material is 120℃-150℃, and the curing time is 1h-2h.

[0026] As an improvement to the above scheme, the side length of the single fluorescent film is A, the height of the LED chip is H1, and the length is B1, satisfying A = (1.1-1.3)(2*H1+B1).

[0027] The side length of the single protective film is C, the height of the LED chip after being coated with the fluorescent film is H2, and the length after being coated with the fluorescent film is B2, satisfying C = (1.3-1.5)(2*H2+B2).

[0028] Implementing this invention has the following beneficial effects:

[0029] In this invention, by coating the sides and top surface of the LED chip with a fluorescent film, the need for a support structure is eliminated, enabling five-sided light emission from the LED chip. This effectively expands the light emission angle of the LED chip. Furthermore, the high concentration of the fluorescent film and its shorter distance from the LED chip increase the excitation degree of the phosphor, thereby improving the brightness of the LED packaging structure. The protective film effectively protects the LED chip, preventing it from contacting moisture and improving the anti-aging properties and reliability of the LED packaging structure and backlight module.

[0030] In this invention, the fluorescent film and the protective film are cured using the same silicone base material, which can enhance the adhesion between the protective film and the fluorescent film, reduce the possibility of water vapor penetration, and reduce the risk of delamination in the LED packaging structure, thereby further improving the reliability of the LED packaging structure. Attached Figure Description

[0031] Figure 1 : A schematic diagram of the existing LED packaging structure;

[0032] Figure 2 : A schematic diagram of the operation of an LED backlight module in the prior art;

[0033] Figure 3 : A schematic diagram of the structure of an LED packaging chip in this invention;

[0034] Figure 4 : A schematic diagram of the structure of an LED backlight module according to the present invention;

[0035] Figure 5 : A schematic diagram of the mold structure in step (1) of this invention;

[0036] Figure 6 : A schematic diagram of the structure after filling with fluorescent adhesive in step (12) of the present invention;

[0037] Figure 7 : A schematic diagram of the cutting of the fluorescent adhesive film in step (13) of the present invention;

[0038] Figure 8 : A schematic diagram of the structure of a single fluorescent film formed after step (13) of the present invention is completed;

[0039] Figure 9 : A partial magnified view of a single fluorescent adhesive film in this invention;

[0040] Figure 10 : A schematic diagram of the structure after step (2) of the present invention is completed;

[0041] Figure 11 : A schematic diagram of the structure formed after step (31) of the present invention is completed;

[0042] Figure 12 : A schematic diagram of the structure of the present invention with an adhesive layer disposed on the upper surface of an LED chip;

[0043] Figure 13 : A schematic diagram of the structure after step (32) of the present invention is completed;

[0044] Figure 14 : A schematic diagram of the operation of step (33) of the present invention;

[0045] Figure 15 : A schematic diagram of the structure after step (33) of the present invention is completed;

[0046] Figure 16 : A schematic diagram of the operation of step (34) of the present invention;

[0047] Figure 17 : A schematic diagram of the structure of a single protective film formed after step (42) of the present invention;

[0048] Figure 18 : A schematic diagram of the process of coating a protective film onto the fluorescent adhesive film in step (5) of the present invention;

[0049] Figure 19 The light intensity distribution curve of the LED packaging structure provided in Embodiment 1 of this invention;

[0050] Figure 20 The light intensity distribution curve of the LED packaging structure provided in Embodiment 2 of this invention;

[0051] Figure 21 The light intensity distribution curve of the LED packaging structure provided in Embodiment 3 of this invention;

[0052] Figure 22 The light intensity distribution curve of the LED packaging structure provided in Embodiment 4 of this invention;

[0053] Figure 23 : The light intensity distribution curve of the LED packaging structure provided in Comparative Example 1 of this invention;

[0054] Figure 24 : A diagram illustrating the light mixing effect of the LED backlight module obtained in Embodiment 1 of this invention;

[0055] Figure 25 : A diagram illustrating the light mixing effect of the LED backlight module obtained in Comparative Example 1 of this invention;

[0056] Figure 26 The chromaticity coordinate distribution diagram of each LED bead in the LED backlight module obtained in Embodiment 1 of this invention;

[0057] Figure 27 The chromaticity coordinate distribution diagram of each LED bead in the LED backlight module obtained in Embodiment 2 of this invention;

[0058] Figure 28 The chromaticity coordinate distribution diagram of each LED bead in the LED backlight module obtained in Embodiment 3 of this invention;

[0059] Figure 29 The chromaticity coordinate distribution diagram of each LED bead in the LED backlight module obtained in Embodiment 4 of this invention;

[0060] Figure 30 The chromaticity coordinate distribution diagram of each LED bead in the LED backlight module obtained in Comparative Example 1 of this invention.

[0061] Reference numerals: 1-LED chip; 2-fluorescent film; 21-single fluorescent film; 22-adhesive layer; 3-protective film; 31-single protective film; 4-substrate; 41-pore; 5-mold; 51-lower mold; 511-groove; 512-protrusion; 52-upper mold; 53-cutting line; 6-plastic film; 7-carrier; 8-lens; 9-diffuser; 10-support. Detailed Implementation

[0062] To make the objectives, technical solutions, and advantages of the present invention clearer, specific embodiments will be described in further detail below.

[0063] To address the above problems, the first aspect of this invention provides an LED packaging structure, please refer to [link / reference]. Figure 3 The device includes: an LED chip 1, a fluorescent film 2, and a protective film 3. The fluorescent film 2 covers the side and top surface of the LED chip 1, and the protective film 3 covers the side and top surface of the fluorescent film 2. The fluorescent film 2 is obtained by mixing and curing a silicone base material and phosphor, and the protective film 3 is obtained by curing the silicone base material in the fluorescent film 2.

[0064] In this invention, by covering the sides and top surface of the LED chip 1 with a fluorescent film 2, the support 10 is avoided, and the LED chip 1 can emit light from five sides, effectively expanding the light emission angle of the LED chip 1. Moreover, the fluorescent film has a high concentration and a shorter distance from the LED chip 1, which improves the excitation degree of the phosphor, thereby improving the luminous brightness of the LED packaging structure. The protective film 3 can effectively protect the LED chip 1, prevent the LED chip 1 from contacting moisture, and improve the anti-aging and reliability of the LED packaging structure.

[0065] Furthermore, the protective film 3 and the fluorescent film 2 are cured using the same silicone base material, which can enhance the adhesion between the protective film 3 and the fluorescent film 2, reduce the possibility of moisture penetration, and reduce the risk of delamination in the LED packaging structure, thereby further improving the reliability of the LED packaging structure.

[0066] Preferably, the ratio of the thickness of the fluorescent film 2 to the thickness of the LED chip 1 is (0.25-1.25):1. This allows the light emitted by the LED chip 1 to fully interact with the phosphor in the fluorescent film 2, achieving better light conversion efficiency and ensuring uniformity and stability of the emitted light. Simultaneously, the fluorescent film 2 at this thickness can protect the LED chip 1 and buffer against external impacts. Exemplarily, the ratio of the thickness of the fluorescent film 2 to the thickness of the LED chip 1 is 0.25:1, 0.5:1, 0.75:1, 1:1, or 1.25:1, but is not limited to these. In some embodiments, the thickness of the fluorescent film 2 is 50μm-150μm. In some embodiments, the thickness of the LED chip 1 is 120μm-200μm.

[0067] Furthermore, the raw materials for preparing the silicone base material include polydimethylsiloxane, a crosslinking agent, a catalyst, and an inhibitor. The polydimethylsiloxane is a vinyl-terminated polydimethylsiloxane, and the crosslinking agent is a polysiloxane containing Si-H groups. In this case, the silicone base material formed by crosslinking the vinyl-terminated polydimethylsiloxane and the Si-H-group-containing polysiloxane exhibits staged curing characteristics. During the first curing, the reaction is slow at low temperatures, allowing for preliminary curing and shaping. During the second curing, the material softens first at high temperatures, then the reaction accelerates, achieving complete curing and forming a fluorescent film 2 covering the sides and top surface of the LED chip 1.

[0068] In some specific and preferred embodiments, the first curing temperature of the silicone base material is 80℃-100℃, and the curing time is 3min-10min; the second curing temperature of the silicone base material is 120℃-150℃, and the curing time is 1h-2h.

[0069] Furthermore, the molar ratio of the Si-H groups to the vinyl groups is (1.2-2):1. By adjusting the crosslinking density of the fluorescent film 2, the refractive index, hardness, impact strength and other properties of the fluorescent film 2 can be further improved.

[0070] Optionally, the vinyl-terminated polydimethylsiloxane has a viscosity of 4000 mPa·s-7000 mPa·s at 25°C and an average molecular weight of 29000-33000.

[0071] Optionally, the Si-H group content in the polysiloxane is 0.5%-0.7%, and the average molecular weight is 2500-3500.

[0072] Optionally, the catalyst is a platinum complex that can provide active Pt to catalyze the addition reaction of silicon-hydrogen bonds (Si-H) with vinyl groups; more preferably, the concentration of the catalyst added to the silicone base is 10ppm-200ppm, which can regulate the curing rate and conversion rate, and ensure the stability and optical properties of the cured fluorescent film 2.

[0073] Optionally, the inhibitor can be an alkynyl alcohol compound or a vinyl cyclic compound, which works synergistically with the catalyst to regulate the reaction rate, ensuring that the phosphor adhesive formed by mixing the silicone base material and the phosphor fully coats the sides and top surface of the LED chip 1, and maintaining a uniform distribution of the phosphor to avoid the formation of bubbles or premature curing of the silicone base material; more preferably, the molar ratio of the inhibitor to the catalyst is (0.5-10):1. The alkynyl alcohol compound includes, but is not limited to, ethynylcyclohexanol, methylbutynol, and 3-methyl-1-dodecyn-3-ol; the vinyl cyclic compound includes, but is not limited to, tetramethyltetravinylcyclotetrasiloxane.

[0074] Furthermore, the ratio of the thickness of the protective film 3 to the thickness of the fluorescent film 2 is (0.3-3):1. This, in conjunction with the fluorescent film 2 of a specific thickness, promotes light emission and propagation, ensuring the angle and uniformity of the emitted light. Simultaneously, the protective film 3 protects the fluorescent film 2, increasing the difficulty for moisture, dust, and other impurities to enter the fluorescent film 2, reducing the impact of the external environment on the fluorescent film 2 and the LED chip 1. In addition, the protective film 3 further enhances the mechanical strength of the entire LED packaging structure, ensuring its lifespan. Exemplarily, the ratio of the thickness of the protective film 3 to the thickness of the fluorescent film 2 is 0.3:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, or 3:1, but is not limited to these ratios. In some embodiments, the thickness of the protective film 3 is 50μm-150μm.

[0075] In some embodiments, the mixing ratio of the silicone base material and the phosphor is 1:(0.4-1) to form a uniformly dispersed and highly fluid colloid, which promotes the formation of a stable film layer on the side and top surface of the LED chip 1, and prevents the phosphor from settling before initial fixation.

[0076] In some specific and preferred embodiments, such as Figure 12 As shown, an adhesive layer 22 is also provided between the fluorescent film 2 and the LED chip 1. The adhesive layer 22 is obtained by curing the silicone base material in the fluorescent film 2, which further enhances the adhesion between the fluorescent film 2 and the LED chip 1.

[0077] Accordingly, the present invention also provides an LED backlight module, including a substrate 4 and the aforementioned LED packaging structure, wherein the LED packaging structure is arranged in an array on the substrate 4. Please refer to [link to relevant documentation]. Figure 4 The substrate 4 has vents 41 penetrating the upper and lower surfaces of the substrate 4, and the vents 41 are located between adjacent LED chips 1. The single LED package structure includes: LED chip 1, a single phosphor film 21, and a single protective film 31. The single phosphor film 21 covers the side and upper surface of the LED chip 1, and the single protective film 31 covers the side and upper surface of the single phosphor film 21.

[0078] Accordingly, the present invention also provides a method for manufacturing an LED backlight module, comprising the following steps:

[0079] (1) Provide a mold 5, and in the mold 5, the fluorescent adhesive obtained by mixing silicone base material and phosphor powder is initially cured to obtain fluorescent adhesive film 2. Cut the fluorescent adhesive film 2 to obtain a single fluorescent adhesive film 21 in the shape of a cross.

[0080] (2) A substrate 4 is provided, and LED chips 1 are fixed on the substrate 4 and arranged in an array;

[0081] (3) Place a single fluorescent adhesive film 21 on the upper surface of the LED chip 1, and use the plastic film 6 to cover the side and upper surface of the LED chip 1 with the single fluorescent adhesive film 21, and completely cure it.

[0082] (4) The silicone base material is initially cured in the mold 5 to obtain a protective film 3. The protective film 3 is cut to obtain a single protective film 31 in the shape of a cross.

[0083] (5) Place a single protective film 31 on the upper surface of the fluorescent film 2, and use the plastic film 6 to cover the side and upper surface of the fluorescent film 2 with the single protective film 31, and then completely cure and shape it.

[0084] The following provides a detailed explanation of each step; please refer to [link / reference]. Figures 5-18 :

[0085] Regarding step (1), a mold 5 is provided, and the fluorescent adhesive obtained by mixing silicone base material and phosphor powder in the mold 5 is initially cured to obtain fluorescent adhesive film 2. The fluorescent adhesive film 2 is cut to obtain a single fluorescent adhesive film 21 in the shape of a cross.

[0086] This step specifically includes:

[0087] (11) Provide a mold 5, the mold 5 including an upper mold 52 and a lower mold 51;

[0088] Please see Figure 5The lower mold 51 is provided with an array of grooves 511, and a protrusion 512 structure is formed between adjacent grooves 511. The side of the upper mold 52 that contacts the lower mold 51 is a planar structure.

[0089] Optionally, the cross-sectional shape of the groove 511 is either square or rectangular, which facilitates the later cutting to form a single fluorescent film 21 with a cross-shaped structure.

[0090] (12) Fill the mold 5 with fluorescent adhesive to allow the fluorescent adhesive to cure initially, and obtain fluorescent adhesive film 2;

[0091] Specifically, fluorescent adhesive is filled into the groove 511 of the lower mold 51; then, it is pressed downwards using the upper mold 52 until it is in close contact with the protrusion 512 structure in the lower mold 51; finally, a heat curing process is performed to initially cure and shape the fluorescent adhesive, and the mold 5 is removed to form a fluorescent adhesive film 2. Please refer to [link to relevant documentation]. Figure 6 The temperature for the heat curing process is 80℃-100℃, and the time is 3min-10min.

[0092] In some embodiments, before filling the groove 511 of the lower mold 51 with fluorescent adhesive, a release agent may be sprayed into the groove 511. The release agent may be a release agent commonly used in the art, and this application does not specifically limit it.

[0093] (13) Cut the fluorescent adhesive film 2 according to the preset cutting line 53 and remove the excess part to obtain a single fluorescent adhesive film 21 in the shape of a cross. Please refer to Figure 7 and Figure 8 ;

[0094] Specifically, please refer to Figure 9 The side length of the single fluorescent film 21 formed after cutting is A, the height of the LED chip 1 is H1, and the length is B1, which satisfies A = (1.1-1.3)(2*H1+B1). Based on this design, the single fluorescent film 21 can completely cover the side and top surface of the single LED chip 1.

[0095] Regarding step (2), a substrate 4 is provided, and LED chips 1 are fixed on the substrate 4 and arranged in an array;

[0096] In this step, please refer to Figure 10 The LED chip 1 is flip-chip soldered onto the substrate 4, specifically using a solder paste reflow soldering process. The substrate 4 has vents 41 penetrating its upper and lower surfaces, and these vents 41 are located between adjacent LED chips 1.

[0097] Regarding step (3), a single fluorescent adhesive film 21 is placed on the upper surface of the LED chip 1, and the single fluorescent adhesive film 21 is wrapped around the side and upper surface of the LED chip 1 using the plastic film 6 and then completely cured and formed.

[0098] This step specifically includes:

[0099] (31) Place the single fluorescent film 21 with a cross-shaped structure on top of the LED chip 1 and heat it to cure it so that the single fluorescent film 21 is initially cured and formed.

[0100] Specifically, please refer to Figure 11 When placing a single fluorescent adhesive film 21 on top of the LED chip 1, it is necessary to control the center of the single fluorescent adhesive film 21 to coincide with the center of the LED chip 1. The temperature of the heat curing process is 80℃-100℃ and the time is 3min-10min.

[0101] In some embodiments, before placing the cross-shaped single fluorescent adhesive film 21 above the LED chip 1, an adhesive layer 22 is further disposed on the upper surface of the LED chip 1. Specifically, please refer to... Figure 12 An adhesive can be applied to the upper surface of the LED chip 1, and the coating height of the adhesive layer 22 is 5μm-20μm. The adhesive is the silicone base material in the fluorescent film 2, meaning the adhesive is a silicone material of the same system as the fluorescent film 2.

[0102] (32) Cover the LED chip 1 with a plastic film 6 and seal it to the four edges of the substrate 4;

[0103] Specifically, please refer to Figure 13 Double-sided tape is pasted on the substrate 4 to tightly adhere the periphery of the plastic film 6 to the periphery of the substrate 4, ensuring that there is no air leakage. The double-sided tape can be a high-temperature resistant double-sided tape to facilitate high-temperature curing treatment later. This application does not make specific limitations on this.

[0104] The plastic film 6 is made of a transparent material. In some embodiments, the plastic film 6 is a non-porous film material of perfluoroether rubber (FFKM), with a thickness of 20μm-50μm and a hardness (Shore A) of 40-60; it has good stretchability and elongation at break of 150%-400%; it has good temperature resistance and can be used under conditions of 5h-6h and 150℃-180℃; the surface has release properties and a peel force ≤10gf / in.

[0105] (33) Under negative pressure, the plastic film 6 is squeezed to form a single fluorescent adhesive film 21, so that the single fluorescent adhesive film 21 is bonded to the side and top surface of the LED chip 1. Then, heat treatment is performed to completely solidify the single fluorescent adhesive film 21.

[0106] Specifically, please refer to Figure 14 and Figure 15 The substrate 4 is placed on a carrier 7 with both suction and blowing modes, and the carrier 7 is placed in an oven. The suction mode of the carrier 7 is activated, allowing air in the space enclosed by the substrate 4 and the plastic film 6 to be extracted from the pores 41 on the substrate 4. The suction force is further increased and maintained. With the help of atmospheric pressure and the softening properties of the phosphor, the plastic film 6 presses the individual phosphor films 21 downwards and toward the side of the LED chip 1, thereby adhering the individual phosphor films 21 to the side and top surface of the LED chip 1. Finally, the oven is heated for a preset time to allow the individual phosphor films 21 to fully cure and form. When an adhesive layer 22 is present, the plastic film 6 also causes the individual phosphor films 21 to adhere to the adhesive layer 22. During heating and curing, the curing of the adhesive allows the individual phosphor films 21 to tightly cover the top surface of the LED chip 1.

[0107] In some embodiments, the heating and curing temperature in the oven is 120℃-150℃, and the heating and curing time in the oven is 1h-2h.

[0108] (34) Remove the plastic film 6 to obtain the LED chip 1 coated with fluorescent film 2;

[0109] Specifically, please refer to Figure 16 The air blowing mode of the carrier plate 7 is turned on, and the plastic film 6 is blown up through the air hole 41 of the substrate 4 to complete the separation of the plastic film 6 from the LED chip 1. Then the plastic film 6 is separated from the substrate 4 and the plastic film 6 is removed.

[0110] Regarding step (4), the silicone base material is initially cured in the mold 5 to obtain a protective film 3. The protective film 3 is then cut to obtain a single protective film 31 in the shape of a cross.

[0111] Step (4) includes:

[0112] (41) Fill the mold 5 with silicone base material to allow the silicone base material to initially solidify, and obtain a protective film 3;

[0113] Specifically, following the operation in step (12), silicone base material is filled into the groove 511 of the lower mold 51; then the upper mold 52 is used to press downwards until it is in close contact with the protrusion 512 structure in the lower mold 51; finally, a heat curing treatment is performed to allow the silicone base material to be initially cured and shaped, the mold 5 is removed, and a protective film 3 is formed. The temperature of the heat curing treatment is 80℃-100℃, and the time is 3min-10min.

[0114] (42) Cut the protective film 3 according to the preset cutting line 53 and remove the excess part to obtain a single protective film 31 in the shape of a cross;

[0115] Specifically, please refer to Figure 17 The side length of the single protective film 31 formed after cutting is C, the height of the LED chip 1 after covering the fluorescent film 2 is H2, and the length after covering the fluorescent film 2 is B2, which satisfies C=(1.3-1.5)(2*H2+B2). Based on this design, the single protective film 31 can completely cover the side and top surface of the single fluorescent film 21.

[0116] Regarding step (5), place a single protective film 31 on the upper surface of the fluorescent film 2, and use the plastic film 6 to cover the side and upper surface of the fluorescent film 2 with the single protective film 31, and then completely cure and shape it.

[0117] In this step, the protective film 3 is coated onto the surface of the fluorescent film 2 using the method in step (4). Specifically, this includes: placing a single protective film 31 in a cross shape on the upper surface of the LED chip 1 corresponding to the fluorescent film 2, and performing a heat curing treatment to initially solidify the single protective film 31; then covering the LED chip 1 with a plastic film 6 and sealing it to the periphery of the substrate 4; next, under a negative pressure environment, the plastic film 6 is used to compress the single protective film 31, achieving adhesion between the single protective film 31 and the side and upper surface of the LED chip 1 fluorescent film 2, followed by a heat treatment to completely solidify the single protective film 31. Figure 18 As shown; finally, the plastic film 6 is removed to obtain the LED chip 1 with a protective film 3 coated on the surface of the fluorescent film 2. Please refer to [link to relevant documentation]. Figure 4 .

[0118] In some embodiments, the heating and curing temperature in the oven is 120℃-150℃, and the heating and curing time in the oven is 1h-2h.

[0119] The present invention will be further described below with reference to specific embodiments:

[0120] Example 1

[0121] This embodiment provides an LED packaging structure, including an LED chip, a fluorescent film, and a protective film. The fluorescent film covers the sides and top surface of the LED chip, and the protective film covers the sides and top surface of the fluorescent film. An adhesive layer is provided between the fluorescent film and the LED chip.

[0122] The ratio of the thickness of the fluorescent adhesive film to the thickness of the LED chip is 0.9:1, and the ratio of the thickness of the protective film to the thickness of the fluorescent adhesive film is 1:1.

[0123] The fluorescent film is obtained by mixing and curing a silicone base material and a phosphor, with a mixing ratio of 1:0.65. The raw materials for preparing the silicone base material include polydimethylsiloxane, a crosslinking agent, a catalyst, and an inhibitor.

[0124] The polydimethylsiloxane is a vinyl-terminated polydimethylsiloxane, the crosslinking agent is a polysiloxane containing Si-H groups, the catalyst is a platinum complex, and the inhibitor is ethynylcyclohexanol; the molar ratio of Si-H groups to the vinyl group is 1.5:1; the concentration of the catalyst in the silica gel base is 100 ppm; and the molar ratio of the inhibitor to the catalyst is 5:1.

[0125] The protective film is obtained by curing the silicone base material in the fluorescent film; the adhesive layer is obtained by curing the silicone base material in the fluorescent film.

[0126] Accordingly, this embodiment provides an LED backlight module, including a substrate and the above-mentioned LED packaging structure, wherein the LED packaging structure is arranged in an array on the substrate, and its fabrication method includes the following steps:

[0127] S1. A mold is provided, and a fluorescent adhesive obtained by mixing silicone base material and phosphor is initially cured in the mold to obtain a fluorescent adhesive film, wherein the curing temperature is 80°C and the curing time is 3 min; the fluorescent adhesive film is cut to obtain a single fluorescent adhesive film in the shape of a cross.

[0128] S2. A substrate is provided, and LED chips are fixed on the substrate and arranged in an array;

[0129] S3. Place a single fluorescent adhesive film on the upper surface of the LED chip, use a plastic film to cover the side and upper surface of the LED chip with the single fluorescent adhesive film, and completely cure it. The curing temperature is 150℃ and the curing time is 2h.

[0130] S4. The silicone base material is initially cured in the mold to obtain a protective film, wherein the curing temperature is 80℃ and the curing time is 3min; the protective film is cut to obtain single protective films in the shape of a cross.

[0131] S5. Place a single protective film on the upper surface of the fluorescent film, and use a plastic film to cover the side and upper surface of the fluorescent film with the single protective film, and completely cure it. The curing temperature is 150℃ and the curing time is 2h.

[0132] Example 2

[0133] This embodiment provides an LED packaging structure, which differs from Embodiment 1 in that:

[0134] The ratio of the thickness of the fluorescent adhesive film to the thickness of the LED chip is 0.25:1, and the ratio of the thickness of the protective film to the thickness of the fluorescent adhesive film is 0.3:1.

[0135] This embodiment also provides an LED backlight module, including a substrate and the above-mentioned LED packaging structure. The LED packaging structure is arranged in an array on the substrate, and its preparation method is the same as in Embodiment 1.

[0136] Example 3

[0137] This embodiment provides an LED packaging structure, which differs from Embodiment 1 in that:

[0138] The ratio of the thickness of the fluorescent adhesive film to the thickness of the LED chip is 1.2:1, and the ratio of the thickness of the protective film to the thickness of the fluorescent adhesive film is 3:1.

[0139] This embodiment also provides an LED backlight module, including a substrate and the above-mentioned LED packaging structure. The LED packaging structure is arranged in an array on the substrate, and its preparation method is the same as in Embodiment 1.

[0140] Example 4

[0141] This embodiment provides an LED packaging structure, which differs from Embodiment 1 in that:

[0142] The fluorescent film is obtained by mixing and curing a silicone base material and a fluorescent powder. The raw materials for preparing the silicone base material include polydimethylsiloxane, crosslinking agent, catalyst and inhibitor.

[0143] The crosslinking agent is polysiloxane, and the molar ratio of polysiloxane to the vinyl group is 1.5:1.

[0144] This embodiment also provides an LED backlight module, including a substrate and the above-mentioned LED packaging structure. The LED packaging structure is arranged in an array on the substrate, and its preparation method is the same as in Embodiment 1.

[0145] Comparative Example 1

[0146] This comparative example provides a conventional LED packaging structure, the structure of which is as follows: Figure 1 As shown, it specifically includes: an LED chip, a bracket surrounding the LED chip, and fluorescent adhesive filling the bracket and encapsulating the LED chip.

[0147] This control group also provides an LED backlight module, including the aforementioned conventional LED packaging structure, substrate, lens, and diffuser. The LED packaging structure is fixed to the substrate and electrically connected to the substrate via wires. The lens covers the LED packaging structure, and the diffuser is located above the LED packaging structure. Its operational schematic is shown below. Figure 2 As shown.

[0148] Performance testing

[0149] 1. Light Intensity Distribution: The light intensity distribution of the LED backlight modules obtained in Examples 1-4 and Comparative Example 1 was tested. The light intensity distribution was measured within the range of the light emission angle from -90° to 90°. A corresponding light intensity distribution curve was plotted with the light emission angle as the abscissa and the relative light intensity as the ordinate. The test results are shown in [Figure Number]. Figures 19-23 .

[0150] Depend on Figures 19-23 It can be seen that the light intensity distribution curves of the LED backlight modules obtained in Examples 1-3 all show a light emission angle of approximately 170°. Figure 22 In Example 4, the light intensity distribution curve of the LED backlight module shows a light emission angle of only 120°; while Figure 23 In the comparative example 1, the light intensity distribution curve of the LED backlight module shows that the light emission angle is only 100°. Figures 19-23 Comparative analysis shows that by covering the sides and top surface of the LED chip with fluorescent film, the present application avoids the need for a support structure, achieves five-sided light emission of the LED chip, and effectively expands the light emission angle of the LED chip.

[0151] 2. Light mixing uniformity: The LED backlight modules obtained in Example 1 and Comparative Example 1 were tested, and the test results are shown in [the table below]. Figure 24 and Figure 25 .

[0152] according to Figure 24 and Figure 25 The comparison revealed that, Figure 24 The light intensity at the edge of the LED chip is close to that at the top, resulting in uniform light output from the LED backlight module. Figure 25 The light intensity is strong directly above the LED chip and weak at the edges, resulting in alternating bright and dark areas and significant light mixing and unevenness. Therefore, this application addresses this issue by coating the sides and top surface of the LED chip with phosphor film, avoiding the need for a support structure and increasing the uniformity of light emission.

[0153] 3. Coordinate Concentration: The chromaticity coordinates of each LED in the LED backlight module obtained in Examples 1-4 and Comparative Example 1 were collected, and the spatial distribution concentration of the coordinates on the CIE chromaticity diagram was analyzed. The test results are shown in […]. Figures 26-30 .

[0154] Through comparative analysis Figures 26-30 It can be seen that by coating the sides and top surfaces of the LED chip with phosphor film and protective film, the excitation degree of phosphor can be improved, thereby improving the color uniformity and manufacturing yield of the LED packaging structure in the backlight module.

[0155] 4. Luminous brightness: The brightness of the LED packaging structures obtained in the examples and comparative examples was tested under the conditions of 65.0mA current and 2.7V voltage. Based on Comparative Example 1, the brightness improvement rate was calculated. The test results are shown in Table 1.

[0156] Table 1. Luminous intensity test results of the examples and comparative examples

[0157]

[0158] As can be seen from the results in Table 1 above, by coating the side and top surfaces of the LED chip with phosphor film and protective film, the excitation degree of phosphor can be improved, thereby increasing the luminous brightness of the LED packaging structure in the backlight module.

[0159] 5. Anti-aging performance: The luminous intensity of the LED packaging structures obtained in the examples and comparative examples was tested at 85℃ and 85% humidity, and the ratio of luminous intensity at different aging time periods to the initial luminous intensity was calculated. The test results are shown in Table 2.

[0160] Table 2 Test results of anti-aging performance of the examples and comparative examples

[0161]

[0162] As can be seen from the results in Table 2 above, by coating the sides and top surfaces of the LED chip with fluorescent film and protective film, the fluorescent film can be effectively protected, the LED chip can be prevented from contacting moisture, and the anti-aging and reliability of the LED packaging structure can be improved.

[0163] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. An LED packaging structure, characterized in that, include: An LED chip, a fluorescent film, and a protective film, wherein the fluorescent film covers the sides and top surface of the LED chip, and the protective film covers the sides and top surface of the fluorescent film; The fluorescent film is obtained by mixing and curing a silicone base material and fluorescent powder. The protective film is obtained by curing the same type of silicone base material as the fluorescent film; The raw materials for preparing the silicone base material include polydimethylsiloxane, crosslinking agent, catalyst and inhibitor. The silicone base material can be cured in stages. The first curing temperature of the silicone base material is 80℃-100℃, and the second curing temperature of the silicone base material is 120℃-150℃. The polydimethylsiloxane is a vinyl-terminated polydimethylsiloxane, the crosslinking agent is a polysiloxane containing Si-H groups, and the molar ratio of the Si-H groups to the vinyl group is (1.2-2):1; The concentration of the catalyst added to the silica gel base is 10ppm-200ppm; The molar ratio of the inhibitor to the catalyst is (0.5-10):

1.

2. The LED packaging structure as described in claim 1, characterized in that, The ratio of the thickness of the fluorescent adhesive film to the thickness of the LED chip is (0.25-1.25):1; the ratio of the thickness of the protective adhesive film to the thickness of the fluorescent adhesive film is (0.3-3):

1.

3. The LED packaging structure as described in claim 1 or 2, characterized in that, The mixing ratio of the silicone base material and the phosphor is 1:(0.4-1).

4. The LED packaging structure as described in claim 1, characterized in that, The catalyst is a platinum complex; The inhibitor is at least one of ethynylcyclohexanol, methylbutynol, 3-methyl-1-dodecyn-3-ol, and tetramethyltetravinylcyclotetrasiloxane.

5. The LED packaging structure as described in claim 1, characterized in that, An adhesive layer is also provided between the fluorescent film and the LED chip. The adhesive layer is obtained by curing the same type of silicone base material as the fluorescent film. The thickness of the adhesive layer is 5μm-20μm.

6. An LED backlight module, characterized in that, It includes a substrate and an LED packaging structure as described in any one of claims 1-5, wherein the LED packaging structure is arranged in an array on the substrate.

7. A method for manufacturing an LED backlight module as described in claim 6, characterized in that, Includes the following steps: A mold is provided, and a fluorescent adhesive obtained by mixing silicone base material and phosphor is initially cured in the mold to obtain a fluorescent adhesive film. The fluorescent adhesive film is then cut to obtain a single fluorescent adhesive film in the shape of a cross. The silicone base material is initially cured in the mold to obtain a protective film. The protective film is then cut to obtain single protective films in the shape of a cross. A substrate is provided, on which LED chips are fixed and arranged in an array; A single fluorescent adhesive film is placed on the upper surface of an LED chip, and a plastic film is used to cover the sides and upper surface of the LED chip, and then completely cured and molded. A single protective film is placed on the upper surface of the fluorescent film, and a plastic film is used to cover the sides and upper surface of the fluorescent film with the single protective film, and then completely cured and formed.

8. The method for preparing the LED backlight module as described in claim 7, characterized in that, The initial curing temperature of the silicone base material is 80℃-100℃, and the curing time is 3min-10min; The complete curing temperature of the silicone base material is 120℃-150℃, and the curing time is 1h-2h.

9. The method for preparing an LED backlight module as described in claim 7, characterized in that, The side length of the single fluorescent film is A, the height of the LED chip is H1, and the length is B1, satisfying A = (1.1 - 1.3)(2 * H1 + B1). The side length of the single protective film is C, the height of the LED chip after being coated with the fluorescent film is H2, and the length after being coated with the fluorescent film is B2, satisfying C = (1.3-1.5)(2*H2+B2).

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