Backlight module and preparation method thereof

Abstract

The present invention provides a backlight module and a preparation method thereof, which relate to the field of LED display lighting technology. The backlight module includes a sealing layer, which is arranged on the first surface of a circuit board and seals a plurality of LED chips. The sealing layer also includes a plurality of arc-shaped protrusion structures on its top surface, and the plurality of arc-shaped protrusion structures correspond one-to-one to the plurality of LED chips. The sealing layer includes a grid-shaped first pre-crosslinking area, the first pre-crosslinking area has a higher reflectivity than other areas of the sealing layer, and the first pre-crosslinking area is surrounded by a plurality of first meshes, and the plurality of LED chips are respectively arranged in the plurality of first meshes. The pre-crosslinking area has lower fluidity and higher reflectivity, wherein the lower fluidity can prevent excessive flow of the sealing layer material in other areas during lamination, thereby ensuring the reliability of the seal; and the higher reflectivity can increase the light reflection between the two LED chips, thereby improving the light mixing effect.

Description

Technical Field

[0001] The present application relates to the field of LED display lighting technology, and in particular to a backlight module and a preparation method thereof. Background Art

[0002] Backlights are often surface light sources formed by backlight modules. These structures include POB (package on board) and COB (chip on board). These structures are achieved by bonding LED chips (either packaged or bare) to a circuit board and then laminating them with a sealing film layer to create the final backlight module structure. During lamination, the film's fluidity can cause it to overflow from the side edges of the circuit board, causing contamination. Furthermore, the LED chips at the edges may experience insufficient or missing adhesive, leading to poor sealing. Summary of the Invention

[0003] One of the purposes of the present invention is to overcome the defects described in the prior art, thereby providing a method for preparing a backlight module, which optimizes the sealing film layer to prevent colloid loss and overflow during the lamination process, while achieving better light mixing effect.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A backlight module, comprising:

[0006] The circuit board comprises a first surface and a second surface opposite to each other, wherein the first surface has a circuit layer;

[0007] A plurality of LED chips are bonded to the circuit layer at intervals;

[0008] a sealing layer disposed on the first surface of the circuit board and sealing the plurality of LED chips, the sealing layer further comprising a plurality of arc-shaped protrusion structures on a top surface thereof, the plurality of arc-shaped protrusion structures corresponding one-to-one to the plurality of LED chips;

[0009] The sealing layer includes a grid-shaped first pre-crosslinking area, which has a higher reflectivity than other areas of the sealing layer. The first pre-crosslinking area is surrounded by a plurality of first mesh holes, and the plurality of LED chips are respectively arranged in the plurality of first mesh holes.

[0010] Furthermore, the thickness of the first pre-crosslinking region is smaller than the thickness of the plurality of LED chips, and the first pre-crosslinking region is in direct contact with the first surface of the circuit board.

[0011] In one embodiment, a second pre-crosslinked region is further included, wherein the material of the second pre-crosslinked region is exactly the same as that of the first pre-crosslinked region, and the shapes of the second pre-crosslinked region correspond to those of the first pre-crosslinked region in vertical direction and are spaced apart by a certain distance.

[0012] Furthermore, the second pre-crosslinked region is formed on the top surface of the sealing layer, and the second pre-crosslinked region is surrounded by a plurality of second mesh holes, and the plurality of arc-shaped protrusion structures are respectively arranged in the plurality of second mesh holes.

[0013] Furthermore, the bottom surface of the second pre-crosslinking region is farther away from the first surface than the top surfaces of the plurality of LED chips.

[0014] In another embodiment, it further includes a plurality of reflective layers disposed on the sealing layer, wherein the plurality of reflective layers are separately disposed on the plurality of arc-shaped protrusion structures, and the plurality of reflective layers are conformal to the plurality of arc-shaped protrusion structures.

[0015] Furthermore, the reflective layer comprises a mixed material of a base material with silica gel as a main component and titanium oxide, wherein the titanium oxide accounts for 15%-30% by weight of the mixed material.

[0016] According to the above structure, the present invention also provides a method for preparing a backlight module, comprising the following steps:

[0017] (1) preparing a semi-cured laminate film layer, wherein the semi-cured laminate film layer is irradiated with light to form a grid-like first pre-crosslinked area on the bottom surface thereof;

[0018] (2) Providing a circuit board, the circuit board comprising a first surface and a second surface opposite to each other, the first surface having a circuit layer; bonding a plurality of LED chips to the circuit layer at intervals;

[0019] (3) Laminating the semi-cured laminate film layer on the first surface of the circuit board and thermally curing it to form a sealing layer that seals the multiple LED chips; the first pre-cross-linked area has a higher reflectivity than other areas of the sealing layer, so that during the lamination process, a plurality of arc-shaped protrusion structures corresponding to the multiple LED chips are formed on the top surface of the sealing layer, and the first pre-cross-linked area is surrounded by a plurality of first mesh holes, and the multiple LED chips are respectively arranged in the plurality of first mesh holes.

[0020] In one embodiment, in step (1), the method further includes forming a grid-shaped second pre-crosslinked region on the top surface by light irradiation, wherein the second pre-crosslinked region is made of the same material as the first pre-crosslinked region, and the second pre-crosslinked region corresponds to the first pre-crosslinked region in shape and is spaced a certain distance apart from the first pre-crosslinked region;

[0021] In step (3), the second pre-cross-linking region is formed on the top surface of the sealing layer, and the second pre-cross-linking region is surrounded by a plurality of second mesh holes, the plurality of arc-shaped protrusion structures are respectively arranged in the plurality of second mesh holes, and the bottom surface of the second pre-cross-linking region is farther away from the first surface than the top surface of the plurality of LED chips.

[0022] In another embodiment, the method further includes step (4): conformally forming a plurality of reflective layers on the sealing layer, wherein the plurality of reflective layers are discretely disposed on the plurality of arc-shaped protrusion structures; and the reflective layers include a mixed material of a base material having silica gel as a main component and titanium oxide, wherein the titanium oxide accounts for 15% to 30% by weight of the mixed material.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] In a method for preparing an optoelectronic packaging structure provided by one embodiment of the present invention, a transparent cover plate with an opening is preliminarily used to cover the light emitting and light receiving chips, and a black resin material is filled using an injection molding port in a substrate. Specifically, the black resin material completely fills the opening of the transparent cover plate to achieve light shielding of the light emitting and light receiving chips.

[0025] Compared with the prior art, one or more embodiments of the above solutions may have the following advantages or beneficial effects:

[0026] The present application provides a backlight module and a preparation method thereof, wherein the backlight module includes a sealing layer, which is arranged on the first surface of a circuit board and seals a plurality of LED chips. The sealing layer also includes a plurality of arc-shaped protrusion structures on its top surface, and the plurality of arc-shaped protrusion structures correspond one-to-one to the plurality of LED chips. The sealing layer includes a grid-shaped first pre-crosslinked area, the first pre-crosslinked area has a higher reflectivity than other areas of the sealing layer, and the first pre-crosslinked area is surrounded by a plurality of first mesh holes, and the plurality of LED chips are respectively arranged in the plurality of first mesh holes. The pre-crosslinked area has lower fluidity and higher reflectivity, wherein the lower fluidity can prevent excessive flow of the sealing layer material in other areas during lamination, thereby ensuring the reliability of the seal; and the higher reflectivity can increase the light reflection between the two LED chips, thereby improving the light mixing effect. Furthermore, by laminating the sealing layer material with the pre-crosslinked area, an arc-shaped protrusion structure can be formed directly above each LED chip, thereby achieving large-angle reflection at the arc-shaped protrusion structure. This design can further enhance the light mixing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 is a bottom view of the semi-cured laminated film layer of the present invention;

[0029] Figure 2 This is a schematic diagram of the state of the semi-cured laminated film layer before lamination according to the first embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the state of the semi-cured laminated film layer before lamination according to the first embodiment of the present invention;

[0031] Figure 4 A schematic diagram of further forming a reflective layer according to the first embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of a semi-cured laminated film layer before lamination according to a second embodiment of the present invention;

[0033] Figure 6 FIG. 1 is a schematic diagram of a state of a semi-cured laminated film layer before lamination according to a second embodiment of the present invention.

[0034] Description of reference numerals:

[0035] 10. Circuit board; 11. LED chip; 12. Welding part; 13. Semi-cured laminate film layer; 14. Pre-cross-linking area; 15. Mesh; 16 / 21. Sealing layer; 17 / 22. Arc-shaped protrusion structure; 18. Reflective layer; 19. Second pre-cross-linking area; 20. First pre-cross-linking area. DETAILED DESCRIPTION

[0036] The following will describe in detail the implementation methods of the present application in conjunction with the accompanying drawings and examples, so that the implementation process of how the present application applies technical means to solve technical problems and achieve corresponding technical effects can be fully understood and implemented accordingly. The embodiments of the present application and the various features therein can be combined with each other without conflict, and the technical solutions formed are all within the scope of protection of this application. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0037] It should be understood that although the terms "first," "second," "third," etc. may be used to describe various elements, components, regions, layers, and / or portions, these elements, components, regions, layers, and / or portions should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, or portion from another element, component, region, layer, or portion. Thus, a first element, component, region, layer, or portion discussed below may be referred to as a second element, component, region, layer, or portion without departing from the teachings of this application.

[0038] It will be understood that spatially relative terms, such as "above," "above," "below," "beneath," etc., may be used herein for convenience to describe the relationship of one element or feature to other elements or features illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, then elements or features described as "below other elements" would then be oriented "above" the other elements or features. Thus, the exemplary terms "below" and "beneath" can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.

[0039] The purpose of the terms used herein is only to describe specific embodiments and is not intended to limit the present application. When used herein, the singular forms "a", "an", and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0040] Embodiments of the present application are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the present application. As such, variations from the illustrated shapes due to, for example, manufacturing techniques and / or tolerances are contemplated. Thus, embodiments of the present application should not be limited to the specific shapes of regions illustrated herein, but rather include deviations in shapes due to, for example, manufacturing techniques.

[0041] In order to fully understand the present application, detailed structures and steps will be provided in the following description to illustrate the technical solutions proposed by the present application. The preferred embodiments of the present application are described in detail below. However, in addition to these detailed descriptions, the present application may also have other implementation methods.

[0042] An embodiment of the present invention provides a backlight module, comprising: a circuit board, comprising a first surface and a second surface relative to each other, wherein the first surface has a circuit layer; a plurality of LED chips, which are bonded to the circuit layer at intervals; a sealing layer, which is arranged on the first surface of the circuit board and seals the plurality of LED chips, the sealing layer also comprising a plurality of arc-shaped protrusion structures on its top surface, the plurality of arc-shaped protrusion structures corresponding one-to-one to the plurality of LED chips; the sealing layer comprises a grid-shaped first pre-cross-linking area, the first pre-cross-linking area has a higher reflectivity than other areas of the sealing layer, and the first pre-cross-linking area is surrounded by a plurality of first mesh holes, wherein the plurality of LED chips are respectively arranged in the plurality of first mesh holes.

[0043] First embodiment

[0044] See Figure 4 The backlight module of this embodiment includes a circuit board 10, a sealing layer 16, a plurality of LED chips 11, and a plurality of reflective layers 18. The circuit board 10 can be a plate-like structure such as a printed circuit board (PCB), a copper-clad ceramic substrate, or a LTCC board, and has at least an upper surface and a lower surface facing each other. A circuit layer (not shown) is provided on the upper surface of the circuit board 10 for electrically connecting the plurality of LED chips 11.

[0045] The LED chips 11 can be mini-LED chips, micro-LED chips, or packaged chips, and are bonded to the circuit layer of the circuit board 10 via corresponding soldering portions 12. The soldering portions 12 can be made of solder or conductive paste. The solder can be formed using a reflow process, while the conductive solder is formed by thermal curing.

[0046] Multiple LED chips 11 are arranged in an array, spaced evenly apart, to form multiple rows and columns. The multiple LED chips 11 can include at least one of red, blue, or green LED chips, and combine with the phosphor in the sealing layer 16 to create a white backlight module.

[0047] The sealing layer 16 seals the multiple LED chips 11 and covers the upper surface of the circuit board 10. The sealing layer 16 is made of transparent and viscous EVA material, which provides a sealing effect after curing. Most importantly, a pre-crosslinked region 14 is provided at the bottom of the sealing layer 16. This pre-crosslinked region 14 is formed by localized light irradiation of the sealing layer material. This pre-crosslinked region 14 has a high reflectivity and, before curing, is more rigid than the rest of the sealing layer.

[0048] The preparation of the pre-crosslinked region 14 can be seen in Figure 1The semi-cured laminate film layer 13 can be formed from uncured ethylene-vinyl acetate copolymer in a sheet-like structure. After shielding the non-crosslinked regions, the film is pre-crosslinked by irradiation with light, such as α-rays, β-rays, or ultraviolet rays. The resulting pre-crosslinked regions 14 are white and reflective, with a reflectivity exceeding 90%. The crosslinked regions also exhibit significant rigidity.

[0049] The pre-crosslinked area 14 occupies 10-25% of the total area of ​​the semi-cured laminate film layer 13, and the grid structure of the pre-crosslinked area 14 is surrounded by a plurality of meshes 15, and the plurality of meshes 15 are used to embed a plurality of LED chips 11, such as Figure 4 The sealing layer 16 is obtained by curing the semi-cured laminate film layer 13 , and the pre-crosslinked region 14 surrounds each LED chip 11 .

[0050] In particular, the height of the sealing layer 16 is higher than the height of each LED chip 11, while the height of the pre-cross-linking region 14 in the sealing layer 16 is lower than the height of each LED chip 11, that is, the thickness of the pre-cross-linking region 14 is less than the thickness of multiple LED chips 11, and the first pre-cross-linking region 14 is in direct contact with the upper surface of the circuit board 10.

[0051] The sealing layer 16 also includes a plurality of curved protrusions 17, integrally formed from the sealing material and corresponding to each of the plurality of LED chips 11, to achieve concentrated light output from each LED chip 11. Each of the curved protrusions 17 is spherical or ellipsoidal, with a large radius of curvature. These curved protrusions 17 are formed during lamination of the semi-cured laminate film 13. Due to the presence of the pre-crosslinked regions 14, the areas between the curved protrusions 17 are less susceptible to deformation, forming a concave valley structure.

[0052] In the above structure, the resulting light mixing effect is not optimal. This is because the presence of the curved protrusion structure 17 increases the light intensity in the center of each LED chip 11, while the light intensity in the area between the two chips is lower, resulting in an uneven surface light source for the backlight module. Therefore, multiple reflective layers 18 are conformally formed on each curved protrusion structure 17. The multiple reflective layers 18 are discrete, with their centers coinciding with the center of the curved protrusion structure 17. There are light-emitting gaps between adjacent reflective layers 18. In this way, the emitted light will be reflected by the reflective layers 18, reducing the light emitted from the center of the LED chip and ensuring the uniformity of the surface light source.

[0053] Reflective layer 18 comprises a mixture of a base material primarily composed of silica gel and titanium oxide, with the titanium oxide comprising 15% to 30% by weight of the mixture. This results in a reflectivity of reflective layer 18 between 50% and 80%, ensuring uniformity between the center and edge light of LED chip 11. However, without curved protrusions 17, the titanium oxide ratio in reflective layer 18 would need to be adjusted to adjust the reflectivity and ensure uniform light output.

[0054] In this embodiment, the light emitted by the LED chip 11 is emitted at an angle of at least 120 degrees. A portion of the light is directly emitted through the reflective layer 18, and most of the light is reflected by the reflective layer 18 and then projected onto the pre-cross-linked area 14 to be reflected again, thereby achieving repeated reflection and achieving the effect of sufficient light mixing.

[0055] The method for preparing the backlight module of this embodiment includes the following steps:

[0056] (1) preparing a semi-cured laminate film layer, wherein the semi-cured laminate film layer is irradiated with light to form a grid-like first pre-crosslinked area on the bottom surface thereof;

[0057] (2) Providing a circuit board, the circuit board comprising a first surface and a second surface opposite to each other, the first surface having a circuit layer; bonding a plurality of LED chips to the circuit layer at intervals;

[0058] (3) Laminating the semi-cured laminate film layer on the first surface of the circuit board and thermally curing it to form a sealing layer that seals the multiple LED chips; the first pre-cross-linked area has a higher reflectivity than other areas of the sealing layer, so that during the lamination process, a plurality of arc-shaped protrusion structures corresponding to the multiple LED chips are formed on the top surface of the sealing layer, and the first pre-cross-linked area is surrounded by a plurality of first mesh holes, and the multiple LED chips are respectively arranged in the plurality of first mesh holes.

[0059] First, see Figure 1 The film is provided by a winding mechanism and cut as needed to obtain the desired pre-cured laminate film layer 13. The pre-cured laminate film 13 can be, for example, 20 cm x 20 cm in size and 3-10 mm thick. Next, one side of the pre-cured laminate film layer 13 is covered with a screen mask and irradiated with light to form pre-crosslinked regions 14, with a pre-crosslinking degree of 10-30%.

[0060] Then, see Figure 2 , provide the above-mentioned circuit board 10, and connect multiple LED chips 11 arranged in an array through the welding part 12, and the multiple LED chips 11 are arranged at equal intervals.

[0061] Finally, see Figure 3 and Figure 4 The semi-cured laminate film layer 13 is laminated on the first surface of the circuit board 10 using a laminating mold (not shown, which may have multiple recessed structures) and thermally cured to form a sealing layer 16 that seals the multiple LED chips 11. During the lamination process, the pre-crosslinked region 14 has low fluidity, while the other regions have high fluidity. Therefore, it is easy to form multiple arc-shaped protrusion structures 17 on the sealing layer 16 that correspond to the multiple LED chips 11. The first pre-crosslinked region 14 is surrounded by multiple meshes 15, and the multiple LED chips 11 are respectively arranged in the multiple meshes 15.

[0062] For further information, see Figure 4 , also includes conformally forming a plurality of reflective layers 18 on the sealing layer 16, and the plurality of reflective layers 18 are discretely arranged on the plurality of arc-shaped protrusion structures 17; and the reflective layer 18 includes a mixed material of a base material with silicone as the main component and titanium oxide, wherein the weight percentage of the titanium oxide in the mixed material is 15%-30%.

[0063] The backlight module provided in this embodiment is formed by directly laminating a semi-cured laminated film layer with a pre-crosslinked area. The process is simple and can solve the problem of small OD value, thereby obtaining a backlight module with sufficient light mixing and uniform light output.

[0064] Second embodiment

[0065] This embodiment provides a backlight module, including:

[0066] The circuit board comprises a first surface and a second surface opposite to each other, wherein the first surface has a circuit layer;

[0067] A plurality of LED chips are bonded to the circuit layer at intervals;

[0068] a sealing layer disposed on the first surface of the circuit board and sealing the plurality of LED chips, the sealing layer further comprising a plurality of arc-shaped protrusion structures on a top surface thereof, the plurality of arc-shaped protrusion structures corresponding one-to-one to the plurality of LED chips;

[0069] It is characterized in that the sealing layer includes a grid-shaped first pre-cross-linking area and a second pre-cross-linking area, the first pre-cross-linking area has a higher reflectivity than other areas of the sealing layer, and the first pre-cross-linking area is surrounded by a plurality of first mesh holes, and the plurality of LED chips are respectively arranged in the plurality of first mesh holes; the second pre-cross-linking area is made of exactly the same material as the first pre-cross-linking area, and the second pre-cross-linking area corresponds to the first pre-cross-linking area in shape up and down and is separated by a certain distance.

[0070] See Figure 6 The basic structure of this embodiment is similar to that of the first embodiment, and its sealing layer 21 is also formed by curing the semi-cured laminated film layer. The difference is that the sealing layer 21 includes a plurality of arc-shaped protrusion structures 22 and a first pre-cross-linked area 20 on its lower surface and a second pre-cross-linked area 19 on its upper surface. The materials of the sealing layer 21, the first pre-cross-linked area 20, and the second pre-cross-linked area 19 are the same as those in the first embodiment, and the formation method is also the same.

[0071] The grid of the first pre-crosslinked region 20 surrounds multiple LED chips 11, and the grid of the second pre-crosslinked region 19 corresponds to the first pre-crosslinked region above and below. In the form of a semi-cured laminate film, the first pre-crosslinked region 20 and the second pre-crosslinked region 19 are formed by localized light irradiation on both sides, thereby forming two white pre-crosslinked regions with high reflectivity above and below.

[0072] In particular, the thickness of the first pre-crosslinking region 20 is smaller than the height of each LED chip 11 , and the bottom of the second pre-crosslinking region 19 is located above the top surface of the LED chip 11 , thereby achieving the best light mixing effect.

[0073] When the backlight module is working, the light is reflected from the second pre-crosslinked area 19 to the first pre-crosslinked area 19, thereby achieving the effect of multiple reflection and light mixing, and solving the problem of too small OD value.

[0074] The method for preparing the backlight module of this embodiment includes the following steps:

[0075] (1) preparing a semi-cured laminated film layer, wherein the semi-cured laminated film layer is irradiated with light to form a first pre-crosslinked region in a grid shape on its bottom surface; and irradiated with light to form a second pre-crosslinked region in a grid shape on its top surface, wherein the second pre-crosslinked region is made of the same material as the first pre-crosslinked region, and the second pre-crosslinked region corresponds to the first pre-crosslinked region in shape and is spaced a certain distance apart;

[0076] (2) Providing a circuit board, the circuit board comprising a first surface and a second surface opposite to each other, the first surface having a circuit layer; bonding a plurality of LED chips to the circuit layer at intervals;

[0077] (3) Laminating the semi-cured laminate film layer on the first surface of the circuit board and thermally curing it to form a sealing layer that seals the multiple LED chips; the first pre-cross-linked area has a higher reflectivity than other areas of the sealing layer, so that during the lamination process, a plurality of arc-shaped protrusion structures corresponding to the multiple LED chips are formed on the top surface of the sealing layer, and the first pre-cross-linked area is surrounded by a plurality of first mesh holes, and the multiple LED chips are respectively arranged in the plurality of first mesh holes.

[0078] Furthermore, in step (3), the second pre-cross-linking region is formed on the top surface of the sealing layer, and the second pre-cross-linking region is surrounded by a plurality of second mesh holes, the plurality of arc-shaped protrusion structures are respectively arranged in the plurality of second mesh holes, and the bottom surface of the second pre-cross-linking region is farther away from the first surface than the top surface of the plurality of LED chips.

[0079] The above are only specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A backlight module, comprising: The circuit board comprises a first surface and a second surface opposite to each other, wherein the first surface has a circuit layer; A plurality of LED chips are bonded to the circuit layer at intervals; a sealing layer disposed on the first surface of the circuit board and sealing the plurality of LED chips, the sealing layer further comprising a plurality of arc-shaped protrusion structures on a top surface thereof, the plurality of arc-shaped protrusion structures corresponding one-to-one to the plurality of LED chips; The sealing layer includes a grid-shaped first pre-crosslinked area, the first pre-crosslinked area has a higher reflectivity than other areas of the sealing layer, and the first pre-crosslinked area is surrounded by a plurality of first mesh holes, and the plurality of LED chips are respectively arranged in the plurality of first mesh holes; Wherein, the thickness of the first pre-crosslinking region is less than the thickness of the plurality of LED chips, and the first pre-crosslinking region is in direct contact with the first surface of the circuit board; The sealing layer further includes a grid-shaped second pre-crosslinked region, the second pre-crosslinked region is made of the same material as the first pre-crosslinked region, and the second pre-crosslinked region corresponds to the first pre-crosslinked region in shape and is spaced a certain distance apart.

2. The backlight module according to claim 1, wherein: The second pre-crosslinked region is formed on the top surface of the sealing layer, and the second pre-crosslinked region is surrounded by a plurality of second mesh holes, and the plurality of arc-shaped protrusion structures are respectively arranged in the plurality of second mesh holes.

3. The backlight module according to claim 2, wherein: The bottom surface of the second pre-crosslinking region is farther away from the first surface than the top surfaces of the plurality of LED chips.

4. The backlight module according to claim 1, wherein: It also includes a plurality of reflective layers disposed on the sealing layer, wherein the plurality of reflective layers are separately disposed on the plurality of arc-shaped protrusion structures, and the plurality of reflective layers are conformal to the plurality of arc-shaped protrusion structures.

5. The backlight module according to claim 4, wherein: The reflective layer comprises a mixed material of a base material with silica gel as a main component and titanium oxide, wherein the titanium oxide accounts for 15% to 30% of the weight of the mixed material.

6. A method for preparing a backlight module, comprising the following steps: (1) preparing a semi-cured laminate film layer, wherein the semi-cured laminate film layer is irradiated with light to form a grid-like first pre-crosslinked area on its bottom surface; (2) providing a circuit board, the circuit board comprising a first surface and a second surface opposite to each other, the first surface having a circuit layer; bonding a plurality of LED chips to the circuit layer at intervals; (3) laminating the semi-cured laminate film layer on the first surface of the circuit board and thermally curing the semi-cured laminate film layer to form a sealing layer that seals the plurality of LED chips; the first pre-crosslinked region has a higher reflectivity than other regions of the sealing layer, so that during the lamination process, a plurality of arc-shaped protrusion structures corresponding to the plurality of LED chips are formed on the top surface of the sealing layer, and the first pre-crosslinked region is surrounded by a plurality of first meshes, and the plurality of LED chips are respectively arranged in the plurality of first meshes; Wherein, in step (1), it also includes forming a grid-shaped second pre-crosslinked area on the top surface by light irradiation, the second pre-crosslinked area is made of the same material as the first pre-crosslinked area, and the second pre-crosslinked area corresponds to the first pre-crosslinked area in shape and is spaced a certain distance apart; In step (3), the second pre-cross-linking region is formed on the top surface of the sealing layer, and the second pre-cross-linking region is surrounded by a plurality of second mesh holes, the plurality of arc-shaped protrusion structures are respectively arranged in the plurality of second mesh holes, and the bottom surface of the second pre-cross-linking region is farther away from the first surface than the top surface of the plurality of LED chips.

7. The method for preparing a backlight module according to claim 6, wherein: The invention also includes step (4): forming a plurality of reflective layers conformally on the sealing layer, wherein the plurality of reflective layers are separately arranged on the plurality of arc-shaped protrusion structures; and the reflective layers include a mixed material of a base material with silica gel as the main component and titanium oxide, wherein the weight percentage of the titanium oxide in the mixed material is 15%-30%.

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