CN114613897A

CN114613897A - LED packaging structure, preparation method and LED backlight module

Info

Publication number: CN114613897A
Application number: CN202210344509.2A
Authority: CN
Inventors: 金中华
Original assignee: Huizhou Jufei Optoelectronics Co ltd
Current assignee: Huizhou Jufei Optoelectronics Co ltd
Priority date: 2022-03-31
Filing date: 2022-03-31
Publication date: 2022-06-10

Abstract

The embodiment of the invention provides an LED packaging structure, a preparation method and an LED backlight module, wherein the LED packaging structure comprises: a substrate on which a pad is provided; the LED chip is welded on the bonding pad; a first lens covering the LED chip; the second lens covers the first lens, the refractive index of the first lens is larger than that of the second lens, a pit is arranged in the center of the top surface of the second lens, and the bottom of the pit is higher than that of the top of the first lens. The first lens and the second lens are directly packaged on the LED chip and the substrate, so that air scattering is reduced, and the luminous efficiency is improved; adopt the first lens and the second lens of different refracting indexes to let the refracting index of first lens be greater than the second lens, set up a pit in the center of the top surface of second lens, the refraction and the reflection of central light make the light at chip center to disperse all around through the refraction cooperation pit of two-layer lens, improve light distribution, improved the luminous angle and the homogeneity of LED lamp.

Description

LED packaging structure, preparation method and LED backlight module

Technical Field

The invention relates to the technical field of LEDs, in particular to an LED packaging structure, a preparation method and an LED backlight module.

Background

The Mini-LED backlight module development is the focus of all recent television manufacturers for showing new technology and being the market in product iteration, the innovation point of the technology is mainly that regional dimming can be realized, million-level contrast is realized, 1000nit of brightness of the module can be realized, after the quantum dot technology is added, high color gamut can be realized, and ultra-thinness in appearance can be realized, but under the condition that the current optical development parameters and design have no industrial standards, how to design a backlight module optical system with more cost performance is the direction of key research of an optical design developer.

At present, most of Mini-LEDs on the market are LEDs with light emitted from the top, and emergent light is deflected by utilizing a secondary lens, but the LED light intensity distribution of the structure is uneven, the central brightness is high, the peripheral brightness is low, and in order to ensure that zones between adjacent Mini-LED components cannot have obvious brightness reduction, the Mini-LED components are required to be arranged more densely, the phase change is increased, the cost is increased, the emergent light is too concentrated, a lamp shadow can be often found through frontal observation, and the light emitted by a single Mini-LED component is uneven.

Therefore, how to improve the uniformity of the Mini-LEDs and reduce the use number of the Mini-LEDs in the backlight has very important significance.

Disclosure of Invention

The technical problem to be solved by the invention is that the current LED chips are not uniformly distributed, so that the light-emitting uniformity of the backlight module is low, and meanwhile, in order to improve the light-emitting uniformity of the backlight module, the number of LEDs in the backlight module needs to be increased, so that the cost is obviously increased, and the energy consumption and the heat productivity are improved. The invention provides an LED packaging structure, a preparation method and an LED backlight module aiming at the technical problems.

In order to solve the above technical problem, the present invention provides an LED package structure, including:

the substrate is provided with a bonding pad;

the LED chip is welded on the bonding pad;

a first lens overlying the LED chip;

the second lens covers the first lens, the refractive index of the first lens is larger than that of the second lens, a pit is arranged in the center of the top surface of the second lens, and the bottom of the pit is higher than that of the top of the first lens.

Optionally, the cross section of the pit is circular; the concave pit has a longitudinal section passing through the center thereof, the side of the longitudinal section is a curve, and the curvature of the curve gradually increases from the outer side to the central axis of the second lens.

Optionally, the shape of the pit includes: any one of a cone shape, a cone-like shape, a truncated cone-like shape, a triangular pyramid shape, a quadrangular pyramid shape, a truncated triangular pyramid shape, and a truncated quadrangular pyramid shape.

Optionally, a semi-transparent diffusion layer or light-shielding layer is filled in all or part of the space of the pit;

or at least one layer of semi-transparent diffusion sheet or shading sheet is arranged on the top or in the middle of the concave pit.

Optionally, the first lens is a fluorescent glue light conversion lens or a first silicone lens;

the second lens is a second silicone lens.

Optionally, the cross-sectional width of the pit is less than or equal to 0.5 mm.

Further, the present invention also provides an LED backlight module, which includes:

the LED package structure of any one of claims 1-7;

and the backlight film component is arranged on the LED packaging structure and used for converting light and adjusting the uniformity of the light.

Further, the invention also provides a preparation method of the LED packaging structure, and the preparation method of the LED packaging structure comprises the following steps:

preparing a substrate including a pad;

welding an LED chip on the bonding pad;

dispensing glue on the LED chip to form a first lens covering the LED chip and curing the first lens;

dispensing glue on the first lens to form a second lens covering the first lens, and simultaneously forming a pit in the center of the top surface of the second lens and curing the second lens; wherein a bottom of the recess is higher than a top of the first lens; the refractive index of the first lens is larger than that of the second lens.

Optionally, the method further includes:

filling a semi-transparent diffusion layer or light shielding layer in all or part of the space of the pit, and curing the diffusion layer or light shielding layer;

or at least one layer of semi-transparent diffusion sheet or shading sheet is arranged on the top or in the middle of the concave pit, and the diffusion sheet or the shading sheet is solidified.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

fig. 1 is a schematic diagram of an LED package structure provided in this embodiment;

fig. 2 is a schematic optical path diagram of the LED package structure shown in fig. 1 provided in this embodiment;

fig. 3 is a schematic diagram of another LED package structure provided in this embodiment;

fig. 4 is a schematic view of another LED package structure provided in this embodiment;

fig. 5 is a schematic optical path diagram of the LED package structure shown in fig. 3 according to this embodiment;

fig. 6 is a schematic partial structure diagram of an LED backlight module according to a second embodiment of the present invention;

FIG. 7 is a schematic view of a partial structure of another LED backlight module according to a second embodiment of the present invention;

fig. 8 is a schematic flow chart of a method for manufacturing an LED package structure according to a second embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The first embodiment is as follows:

for the LED lamp, the light emitting angle is an important parameter, the larger the light emitting angle is, the wider the irradiation range of one LED lamp is, the more the regions can be illuminated, the parameter is especially important in the backlight module of the display screen, because the space reserved for the LED lamp by the backlight module is limited, the volume of the LED lamp and the distance from the LED lamp to the diffusion plate in the backlight module are limited within a certain range, when the number of the LED backlight lamps is less, the uniformity of backlight is easily reduced, and when the number of the LED backlight lamps is increased, the problems of power consumption increase and heat productivity increase are caused.

Referring to fig. 1, fig. 1 is a schematic cross-sectional view of an LED package structure provided in this embodiment. The LED package structure includes: a substrate 101, wherein a pad is arranged on the substrate 101; an LED chip 102, wherein the LED chip 102 is welded on the bonding pad; a first lens 103, wherein the first lens 103 covers the LED chip 102; a second lens 104, wherein the second lens 104 covers the first lens 103, and the refractive index of the first lens 103 is larger than that of the second lens 104; the center of the top surface of the second lens 104 is provided with a concave pit 105, the bottom of the concave pit 105 is higher than the top of the first lens 103, the first lens 103 is attached to the substrate in fig. 1, the LED chip 102 is completely covered and wrapped in the first lens 103, and the second lens 104 is directly attached to the top surface of the first lens 103.

In this embodiment, the substrate 101 optionally includes, but is not limited to, a PCB substrate and a flexible PCB substrate, and a pad (not shown in fig. 1) is further disposed on the substrate 101, and a specific shape and a structure of the pad may be adjusted according to a type of the LED chip and a specific circuit design scheme, which is not limited in this embodiment. The bottom surface of the first lens 103 is directly attached to the LED chip 102 and the substrate 102, so that the bottom surface of the first lens has a groove having the same shape and size as the LED chip 102 in a region corresponding to the LED chip 102.

In this embodiment, the refractive index of the first lens 103 is greater than that of the second lens 104, and light generated by the LED chip enters the second lens 104 from the first lens 103 and undergoes two refractions, and the angle of the light path is further bent around, so as to increase the light emitting angle of the LED package structure, specifically, referring to fig. 2, fig. 2 is a schematic diagram of the light path of the LED package structure shown in fig. 1 provided in this embodiment, three light paths N1, M1, and L1 directly above the LED chip are shown in fig. 2, and it can be seen from the diagram that the angles of the light paths N1, M1, and L1 are increased after the light paths undergo refraction. To facilitate understanding of the scheme of the present application, a practical example is given here, and when the LED chip in the LED package structure is a Mini-LED blue light chip, we find that when the refractive index of the first lens 103 is greater than or equal to 1.53, and the refractive index of the second lens 104 is greater than or equal to 1.47, the light emitting angle and the brightness of the LED package structure are the best. It is understood that when the LED package structure uses other LED chips, the refractive index of the first lens 103 and the refractive index of the second lens 104 may also use other values besides the above values.

As shown in fig. 1 and 2, the LED package structure has a concave pit 105 recessed inward in the center of the top surface of the second lens 104, and the depth of the concave pit 105 is smaller than the thickness of the second lens 104. As shown in fig. 2, three light paths N1, M1 and L1 are shown in fig. 2, and after the concave pit 105 is formed on the top surface of the second lens 104, the light path of N2 is reflected when it irradiates the inner side of the surface of the concave pit 105, so as to further increase the light emitting angle, and at the same time, the brightness of the dark light area around the LED package structure can be increased, so as to improve the uniformity of brightness.

In another embodiment, the cross-section of the dimple is circular; the concave pit has a longitudinal section passing through the center thereof, the side of the longitudinal section is a curve, and the curvature of the curve gradually increases from the outer side to the central axis of the second lens.

In another embodiment, the shape of the pit includes: any one of a cone shape, a quasi-cone shape, a truncated quasi-cone shape, a triangular pyramid shape, a quadrangular pyramid shape, a truncated triangular pyramid shape, and a truncated quadrangular pyramid shape; when the shape of the concave pit is cone-like or truncated cone-like, the surface of the concave pit is a curved surface and the curvature gradually increases in a direction approaching the center of the second lens.

It is understood that the shape of the pit 105 in the present embodiment includes, but is not limited to, including: conical, quasi-conical, truncated quasi-conical, triangular pyramid, quadrangular pyramid, truncated triangular pyramid, and truncated quadrangular pyramid; in order to optimize the reflection angle of the inner surface of the pit 105 and reflect more light toward the periphery, when the shape of the pit 105 is cone-like or truncated cone-like, the shape of the surface of the pit 105 may be optimized to be a curved surface and the curvature gradually increases in a direction approaching the center of the second lens 104. Such structure makes the camber of pit 105's lateral wall everywhere all different, is favorable to the reflection to follow the light of each angle penetrating into pit 105 lateral wall for the effect that light was broken up to the pit is better, can obviously reduce the light intensity of LED chip top central point department, makes LED packaging structure's light-emitting more even, needs to explain that, still has partial light refraction to pass pit 105 to the second lens top outgoing, but the light intensity at second lens top can be less.

In another embodiment, a semi-transparent diffusion layer or light shielding layer is filled in all or part of the space of the pit; or at least one semi-transparent diffusion sheet or light shielding sheet is arranged on the top or in the middle of the concave pit. It should be noted that the semi-transparent light is intended to allow part of the light to pass through and reflect the rest of the light to the surrounding. The pit structure is favorable to the shaping of diffusion layer, compares in directly setting up the diffusion layer at the lens convex surface, and glue can not flow the pit when the point is glued in pit department, is convenient for control the size of diffusion layer.

In another embodiment, the diffusion layer or light-shielding layer and the diffusion sheet or light-shielding sheet include: the transparent colloid comprises transparent colloid and diffusion particles dispersed in the transparent colloid, wherein the diffusion particles are silicon dioxide or titanium dioxide.

As shown in fig. 3 and 4, fig. 3 and 4 are schematic views of another LED package structure provided in this embodiment. The difference between fig. 3 and fig. 4 is that the pits 105 in fig. 3 are filled with a diffusion layer or light-shielding layer 106, while the pits 105 in fig. 4 are provided with a diffusion sheet or light-shielding sheet 107.

In the LED package structure shown in fig. 3, the concave pit 105 in the center of the top surface of the second lens 104 is filled with the diffusion layer or the light shielding layer 106, the concave pit 105 can be filled with the diffusion layer or the light shielding layer 106, or only a part of the concave pit can be filled with the diffusion layer or the light shielding layer 106, the light emitting angle and the surrounding light emitting uniformity of the LED package structure can be changed by more or less filling the diffusion layer or the light shielding layer 106, and the light scattering effect of the LED package structure on light can be changed by changing the components of the diffusion layer or the light shielding layer 106, so as to change the light transmittance and the light reflectance, thereby adjusting the light emitting uniformity. Fig. 3 is a schematic diagram of an optical path as shown in fig. 5, where fig. 5 is a schematic diagram of an optical path of the LED package structure shown in fig. 3 provided in this embodiment, and fig. 5 shows three optical paths, N2, M2, and L2, directly above an LED chip, where most of M2 directly exits the second lens 104 upward without the diffusion layer or the light shielding layer 106, and at least a part of light is reflected to the periphery by the diffusion layer or the light shielding layer 106 after the diffusion layer or the light shielding layer 106 is provided.

In the LED package structure shown in fig. 4, a layer of diffusion sheet or light-shielding sheet 107 is disposed in the concave pit 105 at the center of the top surface of the second lens 104, the diffusion sheet or light-shielding sheet 107 may be disposed on the top of the concave pit 105 or in the middle, the diffusion sheet or light-shielding sheet 107 may be pre-fabricated and then disposed on the concave pit, the diffusion sheet may be formed by curing the diffusion layer described above, the disposition position of the diffusion sheet or light-shielding sheet 107 may change the light-emitting angle and the surrounding light-emitting uniformity of the LED package structure, and the light transmittance and the reflectance of the diffusion sheet 107 may also change the light-scattering effect thereof, thereby adjusting the light-emitting uniformity. It is understood that the diffusion sheet or the light shielding sheet 107 may be provided in a plurality of sheets in addition to one sheet, and the light transmittance and the reflectance may be adjusted by providing a plurality of sheets.

In this embodiment, the shapes of the diffusion layer or light shielding layer 106 and the diffusion sheet or light shielding sheet 107 are matched with the shape of the cross section of the recess 105, and the cross section of the recess 105 is circular, such as conical shape and cone-like shape, so the shapes of the top surfaces of the diffusion layer or light shielding layer 106 and the diffusion sheet or light shielding sheet 107 are also a circle, and the top surfaces of the diffusion layer or light shielding layer 106 and the diffusion sheet or light shielding sheet 107 are also flat and circular, although the top surfaces may also be convex and concave. Considering that the LED package structure in this embodiment is mainly applied to an LED backlight module, when the LED chip is a Mini-LED chip, the diameters of the top surfaces of the diffusion layer or light shielding layer 106 and the diffusion sheet or light shielding sheet 107 may be adjusted within a range of 0.1mm to 0.5mm, but it is understood that, when the LED chip is a conventional chip, the adjustment ranges of the diameters of the diffusion layer or light shielding layer 106 and the diffusion sheet or light shielding sheet 107 may be expanded, for example, 1mm to 5 mm.

In this embodiment, the diffusion layer or light-shielding layer 106 and the diffusion sheet or light-shielding sheet 107 include: the transparent colloid comprises transparent colloid and diffusion particles dispersed in the transparent colloid, wherein the diffusion particles are silicon dioxide or titanium dioxide. Wherein, in the process of manufacturing the diffusion layer, firstly, transparent glue is used for mixing diffusion particles to form liquid or semi-solid mixed colloid, then the mixed colloid is dripped on the pit 105, the pit 105 is fully filled with the mixed colloid, and the mixed colloid is solidified to form the diffusion layer after the surface above the mixed colloid is flat, wherein, under some specific scenes, after the mixed colloid is placed in the pit 105, the mixed colloid can be stood for a period of time to enable the diffusion particles in the mixed solution to settle, because the shape of the pit 105 is the shape of a horn mouth with large upper opening and small lower opening, the concentration of the diffusion particles is larger when the diffusion particles in the diffusion layer settle, the closer to the bottom of the pit 105, the larger the concentration of the diffusion particles is, thereby the reflection effect of the light at the central position of the LED chip by the diffusion particles is better, the better the standing time of the mixed liquid on the pit 105 can be controlled to adjust the concentrations of the diffusion particles at different depths in the pit, to achieve a particular design effect.

In another embodiment, the first lens is a fluorescent gel light conversion lens, or a first silicone lens; the second lens is a second silicone lens.

In this embodiment, the refractive index of the first lens is greater than that of the second lens, and when the first lens is a first silicone lens and the second lens is a second silicone lens, the refractive indexes of the first silicone lens and the second silicone lens can be changed in a manner of adjusting the formula.

In this embodiment, the Mini-LED chip may be further soldered to the solder pad in an inverted manner, the Mini-LED chip is mainly applied to the Mini-LED display screen, and the LED lamp of the backlight module in the Mini-LED display screen is mainly used for generating white light or blue light, so that the LED chip may be selected as the blue light chip, the first lens may be a fluorescent glue light conversion lens when white light needs to be generated, and the first lens may be a first silicone lens when blue light needs to be generated.

In another embodiment, the cross-sectional width of the dimples is 0.5mm or less.

In this embodiment, when the LED chip is a miniLED chip, the cross-sectional width of the pit 104 is controlled to be less than or equal to 0.5mm as much as possible, and a value greater than this affects the light emitting effect at the center, and reduces the uniformity of light.

An embodiment of the present invention provides an LED package structure, including: a substrate on which a pad is provided; the LED chip is welded on the bonding pad; a first lens covering the LED chip; the second lens covers the first lens, the refractive index of the first lens is larger than that of the second lens, a pit is arranged in the center of the top surface of the second lens, and the bottom of the pit is higher than that of the top of the first lens. The first lens and the second lens are directly packaged on the LED chip and the substrate, so that air scattering is reduced, and the luminous efficiency is improved; adopt the first lens and the second lens of different refracting indexes to let the refracting index of first lens be greater than the second lens, set up a pit in the center of the top surface of second lens, the refraction and the reflection of central light make the light at chip center to disperse all around through the refraction cooperation pit of two-layer lens, improve light distribution, improved the luminous angle and the homogeneity of LED lamp.

The second embodiment:

this embodiment provides a LED backlight unit, and LED backlight unit includes: an LED package structure provided in the first embodiment above; and the backlight film component is arranged on the LED packaging structure and used for converting light and adjusting the uniformity of the light.

Referring to fig. 6 and 7, fig. 6 is a schematic partial structure diagram of an LED backlight module provided in this embodiment, and fig. 7 is a schematic partial structure diagram of another LED backlight module provided in this embodiment. In fig. 6 and 7, the LED package structure 202 is an LED backlight assembly, which is used to provide a backlight source for an LED backlight module, and 201 and 301 are both backlight film assemblies, and the backlight film assembly 201 sequentially includes, from bottom to top: a diffusion plate, a prism sheet, and a diffusion sheet; the backlight film assembly 301 comprises, from bottom to top: a diffusion plate, a QD film, a prism sheet, and a diffusion sheet. The reason why the backlight film assembly 301 has one more QD film than the backlight film assembly 201 is that the LED package structure 202 generates light with different colors, and when the LED package structure 202 generates white light, the QD film is not required to convert the white light, and when the LED package structure 202 generates blue light, the QD film is required to convert the blue light into white light. It can be understood that, in this embodiment, the preset distance between the plurality of backlight lamps needs to be adjusted according to an actual situation, and meanwhile, the specific structure of the backlight finishing layer also needs to be adjusted according to a requirement of the backlight, which is not limited in this embodiment. In this embodiment, since the refractive index of the first lens 103 in the LED package structure is greater than the refractive index of the second lens 104, the CHIP PITCH can be increased, the PITCH/OD ratio becomes large, the DBR-free CHIP can be 3:1 or more, the DBR-containing CHIP can be 4:1 or more, and the PITCH can be increased by adjusting the size of the light-shielding glue and the refractive index of the lens glue.

The embodiment also provides a preparation method of the LED packaging structure, which comprises the following steps: preparing a substrate including a pad; welding an LED chip on the bonding pad; dispensing glue on the LED chip to form a first lens covering the LED chip and curing the first lens; dispensing glue on the first lens to form a second lens covering the first lens, and simultaneously forming a pit in the center of the top surface of the first lens and curing the second lens; wherein a bottom of the recess is higher than a top of the first lens; the refractive index of the first lens is larger than that of the second lens.

As shown in fig. 8, fig. 8 is a schematic flow chart of a manufacturing method of the LED package structure provided in this embodiment. The preparation method of the LED packaging structure comprises the following steps:

s101, preparing a substrate comprising a bonding pad.

In this embodiment, the substrate may optionally include but is not limited to a PCB substrate and a flexible PCB substrate, and the substrate is further provided with a pad, and a specific shape and structure of the pad may be adjusted according to a type and a circuit structure of the LED chip, which is not limited in this embodiment.

And S102, welding the LED chip on the bonding pad.

S103, dispensing glue on the LED chip to form a first lens covering the LED chip and curing the first lens.

The structure can be seen in fig. 1, a bottom surface of the first lens in fig. 1 is attached to the LED chip and the substrate, and a top surface of the first lens is a spherical surface extending to the substrate.

Because the first lens is dispensed on the LED chip, the first lens can flow downwards to completely wrap the LED chip, and the bottom surface of the first lens is directly attached to the substrate, so that the bottom surface of the first lens is provided with a groove which is completely the same as the LED chip in shape and size in the area corresponding to the LED chip. The glue in which the first lens is created includes, but is not limited to, silicone glue and fluorescent glue.

S104, dispensing glue on the first lens to form a second lens covering the first lens, and meanwhile forming a pit in the center of the top surface of the second lens and curing the second lens; wherein a bottom of the recess is higher than a top of the first lens; the refractive index of the first lens is larger than that of the second lens.

Structure referring to fig. 1, the bottom surface of the second lens in fig. 1 is attached to the top surface of the first lens.

The center of the top surface of the second lens is sunken inwards to form a pit, so that the top surface of the second lens is of an M-shaped cambered surface structure.

Because the second lens is dispensed on the first lens in a dispensing manner, the bottom surface of the second lens is directly attached to the top surface of the first lens, the center of the top surface of the second lens is recessed inwards, the recess can be generated in a manner including but not limited to extrusion after dispensing, and a recessed area is automatically formed in the center of a circle in a circling dispensing manner.

The method for forming the concave pit in the center of the top surface of the second lens can be, but is not limited to, producing the concave pit by extruding after dispensing, and automatically forming a concave pit in the center of the circle by circling and dispensing.

In another embodiment, after step S104, filling a semi-transparent diffusion layer or light-shielding layer in all or part of the space of the pit, and curing the diffusion layer or light-shielding layer; or at least one layer of semi-transparent diffusion sheet or shading sheet is arranged on the top or in the middle of the concave pit, and the diffusion sheet or the shading sheet is solidified.

The diffusion layer or the shading layer is generated in a concave pit on the top surface of the second lens in a dispensing mode, the amount of the diffusion layer can be controlled, the diffusion sheet or the shading sheet needs to be prefabricated in advance and is directly placed in the concave pit during manufacturing, and the diameters of the diffusion layer or the shading layer and the top surface of the diffusion sheet or the shading sheet are controlled to be 0.1-0.5 mm.

It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.

While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. An LED package structure, comprising:

the substrate is provided with a bonding pad;

the LED chip is welded on the bonding pad;

a first lens overlying the LED chip;

2. The LED package structure of claim 1, wherein a cross-section of said recess is circular; the concave pit has a longitudinal section passing through the center thereof, the side of the longitudinal section is a curve, and the curvature of the curve gradually increases from the outer side to the central axis of the second lens.

3. The LED package structure of claim 1, wherein the shape of the dimple comprises: any one of a cone shape, a cone-like shape, a truncated cone-like shape, a triangular pyramid shape, a quadrangular pyramid shape, a truncated triangular pyramid shape, and a truncated quadrangular pyramid shape.

4. The LED package structure according to claim 1, wherein a semi-transparent diffusion layer or light-shielding layer is filled in all or part of the space of the recess;

or at least one semi-transparent diffusion sheet or light shielding sheet is arranged on the top or in the middle of the concave pit.

5. The LED package structure of claim 4, wherein the diffuser or light shielding layer and the diffuser or light shielding sheet comprise: the transparent colloid comprises transparent colloid and diffusion particles dispersed in the transparent colloid, wherein the diffusion particles are silicon dioxide or titanium dioxide.

6. The LED package structure of claim 1, wherein said first lens is a phosphor gel light conversion lens, or a first silicone lens;

the second lens is a second silicone lens.

7. The LED package structure of any one of claims 1-6, wherein the cross-sectional width of the dimple is 0.5mm or less.

8. An LED backlight module, characterized in that, LED backlight module includes:

the LED package structure of any one of claims 1-7;

and a backlight film assembly disposed on the LED package structure for converting light and adjusting uniformity of light.

9. A preparation method of an LED packaging structure is characterized by comprising the following steps:

preparing a substrate including a pad;

welding an LED chip on the bonding pad;

10. The method for manufacturing an LED package structure according to claim 9, further comprising: