Printed circuit board assemblies and their manufacturing methods, as well as backlight modules and display devices

Abstract

This application relates to the field of backlight module technology, disclosing a printed circuit board assembly and its fabrication method, as well as a backlight module and display device. The printed circuit board assembly of this application includes a printed circuit board and at least one light-emitting diode (LED) chip assembly. The LED chip assembly includes a chip and at least one annular member. The annular member is disposed on the surface of the printed circuit board around the central axis of the chip and is coaxial with the central axis. By providing physical boundary guidance for the optical adhesive on the surface of the printed circuit board with the annular member surrounding the chip, this application effectively solves the problems of weak adhesion and inconsistent forming of the optical adhesive in MiniLED display technology. Therefore, it can significantly improve the bonding strength between the adhesive and the printed circuit board, reduce the risk of delamination and cracking, and ensure the consistency of the optical lens structure of each pixel, thereby improving display uniformity, reducing the occurrence of "mura" phenomenon, and having the advantages of improving product reliability and display uniformity.

Description

Technical Field

[0001] This application relates to the field of backlight module technology, and in particular to a printed circuit board assembly and its manufacturing method, as well as a backlight module and a display device. Background Technology

[0002] In the field of MiniLED display technology, the Chip-on-Board (COB) process is the mainstream manufacturing method, directly bonding micro-LED chips to the surface of a printed circuit board. To achieve chip protection and optical performance control, conventional processes use fully automated dispensing equipment to spray high-refractive-index optical adhesive, such as silicone or epoxy resin, directly above each LED chip, forming a localized spherical lens structure. This structure aims to expand the light-emitting angle and provide mechanical protection and moisture resistance. However, the surface of printed circuit boards is generally covered with a smooth solder resist layer, such as a white oil coating, which has low surface energy, resulting in insufficient bonding strength between the optical adhesive and the substrate interface. Under high temperature and humidity environments or thermal cycling stress, the interface is prone to failure phenomena such as delamination and cracking, seriously impairing the long-term reliability of the product. Furthermore, the dispensing process is a non-contact operation; the adhesive drops onto the substrate and spreads based on its own leveling properties. Due to inherent fluctuations in the microscopic flatness, local cleanliness, and temperature distribution of the printed circuit board surface, the final spherical height, radius of curvature, and geometric symmetry of the adhesive in each chip area exhibit significant differences. This inconsistency in forming directly leads to uneven pixel-level light emission angles and brightness distribution, producing a visually discernible mura effect, namely a cloud-like uneven brightness phenomenon, which greatly weakens the uniformity and visual quality of the displayed image.

[0003] While existing technologies attempt to alleviate the problem by optimizing colloid viscosity or adjusting dispensing parameters, the lack of effective structural guidance on the substrate surface means that colloid spreading remains dominated by random factors, failing to achieve stable and controllable molding results. Furthermore, traditional solutions lack integrated active optical control mechanisms, limiting their ability to guide the light path and hindering further improvements in light extraction efficiency and viewing angle expansion. Therefore, existing technologies urgently need improvement to address these issues. Summary of the Invention

[0004] In view of this, the purpose of this application is to provide a printed circuit board (PCB) assembly and a method for manufacturing the same, which aims to solve the problems of insufficient optical adhesive bonding strength and inconsistent forming, thereby improving the product reliability and display uniformity.

[0005] Another objective of this application is to provide a backlight module and display device based on the PCB assembly described in this application.

[0006] To achieve the above objectives, as a first aspect of this application, a printed circuit board assembly is provided, including a printed circuit board and at least one light-emitting diode chip assembly; The light-emitting diode chip assembly includes a chip and at least one annular member; the chip is disposed on the surface of the printed circuit board and is connected to the circuit of the printed circuit board; the annular member is disposed on the surface of the printed circuit board around the central axis of the chip and is coaxial with the central axis.

[0007] Optionally, at least one optical microstructure is provided in at least one of the regions enclosed by the annular member and the chip, and in at least one region enclosed by the adjacent annular member, the optical microstructure being capable of widening the light emission angle.

[0008] Optionally, the optical microstructure includes one or more of the following: microlenses, micropyramids, and gradient refractive index microstructures formed from photosensitive materials.

[0009] Optionally, the annular component includes one or more of a circle and a regular polygon.

[0010] Optionally, the height of the annular member is 5-10 μm; and / or The width of the annular component is 10-50 μm; and / or The spacing between the annular components is 0.1-1 mm.

[0011] As a second aspect of this application, a method for fabricating a printed circuit board assembly as described in this application is provided, comprising: Provide printed circuit boards; At least one light-emitting diode (LED) chip is disposed on the surface of the printed circuit board, and at least one annular member is disposed around the central axis of each LED chip, with each annular member being coaxial with the central axis around which it is disposed.

[0012] Optionally, at least one optical microstructure is disposed in at least one region within the area enclosed by the annular member surrounding the central axis of each of the light-emitting diode chips.

[0013] Optionally, the optical microstructure is formed using a photosensitive material through a photolithography process, and the optical microstructure includes one or more of the following: microlenses, micropyramids, and gradient refractive index microstructures.

[0014] As a third aspect of this application, a backlight module is provided, including a frame, a backplate, a light guide plate, a reflector, an optical film assembly, and the printed circuit board assembly described in this application. The chips of the printed circuit board assembly are covered with an adhesive, which is confined within the area enclosed by the annular member.

[0015] As a fourth aspect of this application, a display device is provided, including a liquid crystal panel and the backlight module described in this application.

[0016] This application effectively solves the problems of weak adhesion and inconsistent forming of optical adhesive in MiniLED display technology by setting an annular component around the chip on the surface of the printed circuit board to provide physical boundary guidance for the optical adhesive. This significantly improves the bonding strength between the adhesive and the printed circuit board, reduces the risk of delamination and cracking, and ensures the consistency of the optical lens structure of each pixel, thereby improving display uniformity, reducing the occurrence of "mura" phenomenon, and offering advantages in improving product reliability and display uniformity. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments of this application and their descriptions are used to explain this application and do not constitute an undue limitation of this application. Figure 1 The diagram shown is a schematic diagram of the structure of the light-emitting diode chip assembly of this application; Figure 2 The diagram shown is a schematic representation of the structure of the light-emitting diode chip assembly (with optical microstructure) of this application. Figure 3 The diagram shows the structure of the LED chip assembly after adhesive dispensing. Figure 4 The image shown is a physical picture of the LED chip assembly after adhesive dispensing. Figure 5 The diagram shows a comparison of light rays from a light-emitting diode chip assembly with and without an optical microstructure array; the left half shows the light rays without an optical microstructure array, and the right half shows the light rays with an optical microstructure array.

[0018] Explanation of icon numbers: Table 1 Detailed Implementation

[0019] This application discloses a printed circuit board assembly and its fabrication method, as well as a backlight module and display device. Those skilled in the art can refer to the content of this application and appropriately modify the process parameters to achieve the desired results. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this application. The products described in this application have been described through preferred embodiments. Those skilled in the art can obviously make modifications or appropriate changes and combinations to the products described herein without departing from the content, spirit, and scope of this application to implement and apply the technology of this application. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0020] It should be noted that all directional indicators in this article (such as up, down, left, right, front, back, etc.) are only used to explain the relative positional relationship and movement of the components in a specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0021] In this document, unless otherwise expressly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0022] Furthermore, the technical solutions of the various embodiments of this application can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by this application. It should be understood that the specific embodiments described herein are merely for explaining this application and are not intended to limit this application. In this document, relational terms such as "first" and "second", "step 1" and "step 2", and "(1)" and "(2)" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including", or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising a..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Furthermore, the embodiments and features described in this application can be combined with each other, provided there is no conflict.

[0023] The following provides a further description of a printed circuit board assembly, its manufacturing method, a backlight module, and a display device provided in this application.

[0024] For ease of understanding, the following explains some key terms in this embodiment: Printed circuit board (PCB) assembly: refers to an integrated structure that combines a printed circuit board and a light-emitting diode (LED) chip assembly. Its function is to provide a basic platform for electrical connection, mechanical support, and photoelectric conversion.

[0025] Printed circuit board (PCB): refers to a substrate used to carry electronic components and provide electrical connections. It is usually composed of insulating materials and conductive layers. In this application, it is used to mount light-emitting diode chips.

[0026] Light-emitting diode (LED) chip assembly: refers to an integrated unit that includes a light-emitting diode chip and its auxiliary structures (such as ring components), responsible for converting electrical energy into light energy.

[0027] Chip: refers to the core light-emitting unit of a light-emitting diode, which is usually a miniature semiconductor device that generates light through electrical excitation.

[0028] Ring-shaped components: These are structures with a ring-shaped geometry arranged around the central axis of the chip. Their main function is to provide physical boundary constraints and guidance for subsequent colloids, thereby optimizing colloid formation and enhancing adhesion.

[0029] Central axis: refers to the imaginary axis passing through the geometric center of the chip and perpendicular to the surface of the printed circuit board. The ring-shaped components are set around this axis and are coaxial with it to ensure structural symmetry.

[0030] Traditional MiniLED display technology uses a COB (Chip-on-Board) process to bond the chip to a printed circuit board and then forms the optical lens structure through adhesive dispensing. However, existing technologies suffer from insufficient adhesion between the optical adhesive and the printed circuit board surface, leading to problems such as delamination and cracking. Furthermore, the dispensing process relies on the adhesive's own leveling properties, resulting in inconsistent adhesive formation. This, in turn, causes uneven light emission angles and brightness among pixels, producing a "mura" phenomenon that severely affects display uniformity.

[0031] Based on the aforementioned technical problems of conventional COB processes, one aspect of this application proposes a printed circuit board assembly, including a printed circuit board and at least one light-emitting diode (LED) chip assembly. The LED chip assembly includes a chip and at least one annular member. The chip is disposed on the surface of the printed circuit board and is in circuit communication with the printed circuit board. The annular member is disposed on the surface of the printed circuit board around the central axis of the chip and is coaxial with the central axis.

[0032] See, for example Figure 1 The printed circuit board assembly includes a printed circuit board (not shown) and at least one light-emitting diode chip assembly. Figure 1(As shown). The printed circuit board serves as the basic support platform, and can be made of materials such as FR-4 or CEM-3. Its surface typically has conductive lines for electrical connections and a solder mask layer for insulation protection. The light-emitting diode (LED) chip assembly is then mounted on this printed circuit board to achieve the light-emitting function.

[0033] The light-emitting diode chip assembly further includes a chip 1 and at least one annular member 2. Chip 1 is the core unit for light emission, and its size can be selected according to actual application requirements; for example, it can be a MiniLED or MicroLED chip. The chip is disposed on the surface of a printed circuit board using, for example, a die-bonding process, and is electrically connected to a pre-set circuit on the printed circuit board to ensure that the chip can normally receive electrical energy and emit light.

[0034] The annular component 2 is one of the key structures of this application. It is disposed on the surface of the printed circuit board around the central axis of the chip 1. The number of such components can be 1-5, for example, 1, 2, 3, 4, 5, etc., with each annular component disposed around the central axis of the chip 1 on the surface of the printed circuit board. The annular component 2 is coaxial with the central axis of the chip 1, ensuring structural symmetry. The annular component 2 can be disposed in various ways. For example, it can be formed directly on the surface of the printed circuit board through processes such as photolithography, printing, molding, and imaging exposure, or it can be pre-formed and fixed by bonding. The material of the annular component 2 can be selected to have good adhesion to the surface of the printed circuit board, such as high-resolution, high-viscosity special solder resist ink or photosensitive resin (photosensitive resin). The height and width of the annular component can be designed according to the viscosity, surface tension, and required optical lens size of the optical colloid to effectively restrict the lateral flow of the colloid and guide the optical colloid to form the desired shape. By utilizing the physical boundary effect of this ring-shaped component, the spreading range and final shape contour of the optical adhesive can be effectively controlled during the subsequent dispensing process, thereby improving the consistency of the adhesive formation and increasing the contact area between the adhesive and the printed circuit board surface, thus enhancing adhesion.

[0035] In some of the solutions described above in this application, annular members are proposed to guide the formation of colloids. However, in this process, the light emission angle may not be wide enough or uniform, affecting the display effect. In response, this application further proposes that at least one optical microstructure be provided in at least one of the regions enclosed by the annular member and the chip, and in at least one region enclosed by an adjacent annular member. The optical microstructure can widen the light emission angle.

[0036] See, for example Figure 2In this context, the region 4, which is the area enclosed by the annular member and the chip, refers to the central region of the LED chip assembly that is defined by the annular member 2 closest to chip 1 and directly covers chip 1. This region is the main emission path of light emitted from the chip, and its optical characteristics are crucial to the overall light emission effect. The optical microstructure 3 can be directly formed on the surface or inside the encapsulant in this region, or it can be prefabricated on the surface of a printed circuit board and then covered by an encapsulant.

[0037] The region 5 enclosed by adjacent annular members refers to the annular space defined between two adjacent annular members 2 on the surface of the printed circuit board. This region assists in the further diffusion and angular expansion of light. Optical microstructures 3 can be formed on the surface of the printed circuit board within this region and then covered by an encapsulating optical colloid. See example below. Figure 3 Schematic diagram and Figure 4 The actual image shows that after dispensing, the optical colloid 6 is effectively confined inside the annular component 2 and covers the entire LED chip assembly. The optical colloid 6 forms a spherical crown or a volcano-shaped depression with a distinct inward indentation at the top center. The main function of the depression at the top of the latter-shaped optical colloid is to reduce the concentration of light energy in the central area of ​​the LED top, thereby avoiding excessive brightness in the center, and to guide the light to the side, thereby increasing the light emission angle.

[0038] At least one optical microstructure is disposed within at least one region. This technical feature clarifies the arrangement location and quantity of the optical microstructures. Choosing to place them within "at least one region" means that, depending on actual needs and optical design, the optical microstructures 3 can be arranged in region 4 adjacent to the chip, region 5 enclosed by adjacent annular components, or a combination of both. "At least one optical microstructure" indicates that, in terms of type, a single type of optical microstructure 3 can be used, or multiple types of optical microstructures 3 can be combined. In terms of quantity, it can be 1, 2, 3...50...100...1000 or more optical microstructures 3, the specific number being adjusted according to the size of the region and requirements. These optical microstructures can be arranged in a regular array to maximize light extraction efficiency, for example, arranged in a regular discrete, radial pattern centered on the central axis of chip 1. Specifically, these optical microstructures can be precisely formed within a specified region using micro-nano fabrication techniques, such as photolithography, nanoimprinting, and laser direct writing, to create a microstructure array with specific geometric shapes and optical properties.

[0039] The optical microstructure 3 can broaden the light emission angle, a technical feature that elucidates the core function of optical microstructures. By precisely controlling the light propagation path, optical microstructures can alter the refraction, reflection, diffraction, or scattering behavior of light, thereby effectively redistributing light rays originally concentrated within a smaller angular range to a wider emission angle range. For example, by designing the surface morphology of the microstructure (such as curved surfaces, conical surfaces, prism surfaces), the principles of refraction and total internal reflection can be used to deflect light as it passes through the microstructure, thereby expanding the light emission angle; or by introducing microstructures with specific periodic or random distributions, the diffraction or scattering effects of light can be used to scatter light in multiple directions, achieving a broadening of the light emission angle.

[0040] See, for example Figure 4 In the printed circuit board assembly, based on the guidance of optical colloid formation using the annular component 2, optical microstructures 3 are further set in the key optical path region (the region 4 enclosed by the annular component and the chip and / or the region 5 enclosed by the adjacent annular component). These optical microstructures 3 can actively regulate the light propagation path and effectively widen the light emission angle of the light-emitting diode chip 1 through optical effects such as refraction, reflection, or scattering; while in the assembly without optical microstructures 3, the light emission efficiency is significantly reduced. This not only solves the problem of insufficient light emission angle in the prior art, but also optimizes the light distribution, making the light emission more uniform, thereby significantly improving the brightness uniformity of the display device, eliminating the "mura" phenomenon, and improving the overall display effect and user visual experience.

[0041] In some embodiments described above in this application, an optical microstructure 3 is proposed to broaden the light emission angle. However, during its implementation, the specific form of the optical microstructure 3 may affect the stability and effectiveness of its optical performance, requiring more precise control. Therefore, this application further proposes that the optical microstructure 3 includes one or more of the following: a microlens formed from photosensitive material, a micropyramid, or a gradient refractive index microstructure.

[0042] The formation of optical microstructures using photosensitive materials refers to utilizing the chemical or physical changes that materials undergo under specific light irradiation to precisely shape microstructures through precision processes such as photolithography. For example, various photoresists, such as positive or negative photoresists, can be selected. These undergo polymerization or decomposition reactions under ultraviolet light or other specific wavelengths of light, followed by removal of specific areas using a developer, thereby forming a pre-defined microstructure pattern on the surface of a printed circuit board. The monomers for positive photoresists can be modified acrylate systems with high transmittance (>90% @450nm), resistance to yellowing, and compatibility with optical adhesives. Alternatively, photocurable resins, such as ultraviolet-curable resins, can be used. These rapidly cure under light irradiation, enabling the construction of complex three-dimensional microstructures through 3D printing or micro / nano imprinting techniques. This combination of material selection and process ensures high precision, high uniformity, and good repeatability in the microstructure manufacturing process.

[0043] A microlens is a lens unit with dimensions on the micrometer scale. Its main function is to focus, collimate, or diffuse light through refraction. In practical applications, microlenses can be formed in various ways. For example, they can be formed using a photoresist reflow process, where after the photoresist pattern is formed, heating is used to create a smooth, spherical or aspherical structure under the influence of surface tension. Another method is to use grayscale photolithography to directly form a microlens array with a continuous curved surface profile on a photosensitive material by controlling the exposure dosage.

[0044] Micropyramids are microstructures with conical or pyramidal cross-sections. Their main function is to alter the direction of light propagation by utilizing the principles of light reflection or refraction, thereby achieving light scattering or guidance. Micropyramids can be fabricated using anisotropic etching techniques to form pyramidal structures with specific crystal facet angles on crystalline materials such as silicon. These structures are then used as molds to replicate the structure onto photosensitive material layers via imprinting or other methods. Alternatively, high-precision three-dimensional processing techniques such as laser direct writing or two-photon polymerization can be used to directly construct the desired micropyramidal structure within the photosensitive material.

[0045] Gradient refractive index microstructures refer to microstructures in which the refractive index of a material exhibits a continuous spatial variation. This structure can guide the light path through the bending effect of light in different refractive index regions, achieving focusing, collimation, or diffusion of light. Its formation methods include, but are not limited to: during photopolymerization or photocrosslinking processes, precisely controlling the light intensity distribution to regulate the concentration gradient of monomers or crosslinking agents, thereby forming a refractive index gradient in the photosensitive polymer; or introducing dopants of different concentrations into the material through methods such as ion exchange to achieve a gradual change in refractive index.

[0046] The optical microstructure 3 employs photosensitive materials combined with precision photolithography, ensuring highly accurate, uniform, and repeatable geometry. This avoids optical performance fluctuations caused by material or process variations, significantly improving the stability and consistency of optical performance. Microlenses, micropyramids, and gradient refractive index microstructures each possess unique optical control capabilities. For example, microlenses diffuse light through refraction, micropyramids alter the light path through reflection or refraction, and gradient refractive index microstructures guide light through varying refractive indices. The combined application of these specific structures allows for more precise and flexible optical path control, enabling synergistic optimization of light diffusion and distribution. This effectively widens the light emission angle and significantly improves light extraction efficiency within the region 4 enclosed by the annular component 2 adjacent to chip 1 and the region 5 enclosed by the adjacent annular component 2, ultimately improving display uniformity.

[0047] In some of the solutions described above in this application, an annular member 2 is proposed to enclose the area of ​​the chip 1 and guide the optical colloid 6 to form or to set the optical microstructure 3. However, in its implementation, since the shape of the annular member 2 is not specifically defined, it may lead to irregular geometry of the enclosed area, affecting the consistency of the optical colloid 6 formation and the uniformity of the optical microstructure distribution, thereby exacerbating the problem of uneven emission angle and brightness. Based on this, this application further proposes that the annular member 2 includes one or more of the following: a circle, a regular polygon.

[0048] Circular or regular polygonal shapes are preferred geometries for annular components, designed to provide a regular and symmetrical enclosure area. Their function is to ensure the geometric regularity and symmetry of the enclosure area, thereby providing consistent boundary conditions to precisely guide the leveling of optical adhesive or the placement of optical microstructures. When the annular component 2 is circular, it can be a complete circular ring structure. When the annular component 2 is a regular polygon, it can be a closed structure such as a square, regular hexagon, or regular octagon. When the annular component 2 includes one or more shapes, for example, a combination structure with a circular inner ring and a square outer ring can be used, or different shapes of annular components 2 can be used in different chip areas to adapt to specific optical design or chip layout requirements.

[0049] When the optical colloid 6 is confined within a circular or regular polygonal area, its leveling process is precisely guided, resulting in a highly consistent spherical or near-spherical lens structure. This ensures the uniformity of the height, radius of curvature, and symmetry of the colloid above each chip. Simultaneously, if optical microstructures 3 are located within regions 4 and 5, these microstructures can also achieve a uniform and controllable arrangement within the regular boundaries, thereby synergistically improving light extraction efficiency and the uniformity of the emission angle. This regular geometry significantly reduces the risk of uneven emission angle and brightness, thus improving the product's optical performance stability and display uniformity.

[0050] In some of the solutions described above in this application, annular members 2 are proposed to enclose the area of ​​chip 1 and guide the formation of optical colloid 6. However, during its implementation, if the size of the annular member 2 is inappropriate, it may lead to poor flow control of the optical colloid 6, unstable adhesion, or unsatisfactory optical microstructure 3. Based on this, this application further proposes that the height of the annular member 2 is 5-10 μm; and / or the width of the annular member 2 is 10-50 μm; and / or the spacing of the annular members 2 is 0.1-1 mm.

[0051] The height of the annular member 2 refers to its vertical dimension extending upward from the surface of the printed circuit board. To ensure that the annular member 2 can effectively enclose the optical colloid 6 and guide its formation, while avoiding unnecessary obstruction of light propagation, its height is limited to the range of 5-10 μm, such as 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, or any value between the two.

[0052] The width of the annular member 2 refers to its lateral dimension on the surface of the printed circuit board, perpendicular to its circumferential direction. To provide sufficient surface area to enhance the adhesion strength between the optical colloid and the substrate, and to precisely control the lateral spread of the colloid, its width is limited to the range of 10-50 μm, such as 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, 50μm, or any value between the two.

[0053] The spacing of the annular components 2 refers to the radial distance from the edge of the light-emitting surface of the chip 1 to the innermost annular component 2, and the radial spacing between any two adjacent annular components 2. In order to more effectively widen the light emission angle and significantly improve the light extraction efficiency in the region 4 enclosed by the annular component 2 adjacent to the chip 1 and the region 5 enclosed by the adjacent annular component 2, the spacing is limited to the range of 0.1-1mm, such as 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm or any value between the two.

[0054] In a second aspect of this application, a method for fabricating a printed circuit board assembly is provided, comprising the following steps: Provide printed circuit boards; At least one light-emitting diode chip 1 is disposed on the surface of a printed circuit board, and at least one annular member 2 is disposed around the central axis of each light-emitting diode chip 1, with each annular member 2 being coaxial with the central axis around which it is disposed.

[0055] In the fabrication steps of the printed circuit board (PCB), the PCB serves as the physical carrier and electrical connection platform for the light-emitting diode chip 1 and the ring-shaped component 2. The PCB can be a bare board obtained through standard PCB manufacturing processes, with pre-formed circuit traces, pads, and other structures for subsequent component mounting and electrical connection; alternatively, the PCB can be a partially assembled substrate, such as one with other passive components mounted on it. Furthermore, the material and type of the PCB can be selected according to actual application requirements; for example, it can be a rigid PCB, a flexible PCB (FPC), or a metal-based PCB (MCPCB) to meet the requirements of different application scenarios for heat dissipation performance or flexibility.

[0056] In the step of setting at least one light-emitting diode (LED) chip 1 on the surface of a printed circuit board, the aim is to fix the LED chip 1 on the printed circuit board and achieve its electrical connection with the circuit of the printed circuit board so that it can emit light normally. This setting process can be achieved in a variety of ways. For example, a die bonding process can be used to directly mount the LED chip 1 onto the pads of the printed circuit board, and the electrical connection between the chip and the circuit can be achieved through wire bonding or flip-chip technology.

[0057] In the step of setting at least one annular member 2 around the central axis of each LED chip 1, with each annular member 2 coaxial with the central axis it surrounds, its core function is to provide precise physical boundaries and guidance for the subsequent forming of the optical colloid 6, ensuring that the colloid can spread uniformly and symmetrically around the chip 1 and enhancing the adhesion between the colloid and the substrate. The setting of this annular member 2 can be achieved using various high-precision microfabrication techniques. For example, it can be achieved through photolithography, where a layer of photosensitive material (such as photoresist) is pre-coated on the surface of the printed circuit board, and then the annular member coaxial with the central axis of the LED chip is precisely formed through mask exposure, development, and curing. This method enables high-precision microstructure manufacturing, ensuring the accuracy of the size and position of the annular member. Alternatively, screen printing can be used. Furthermore, multiple designed annular members 2 can be pre-formed around the pads of each chip 1, and then the chip 1 is set up through a curing process. The annular members 2 can be made using high-resolution, high-viscosity special solder resist ink (or photosensitive resin).

[0058] In a further preparation method of this application, at least one optical microstructure 3 is provided in at least one region within the area enclosed by the annular member 2 surrounding the central axis of each light-emitting diode chip 1.

[0059] The region enclosed by the annular member 2 surrounding the central axis of each LED chip 1 is the space between the LED chip 1 and the annular member 2, or the space enclosed by the interior of the annular member 2. This ensures that the optical microstructure 3 can fit tightly with the annular member 2 and the subsequently filled optical colloid 6, thereby achieving effective control of light. For example, this region can refer to the entire planar area inside the annular member 2, i.e., multiple regions 5; or it can be the annular gap between the innermost inner wall of the annular member 2 and the outer wall of the LED chip 1, i.e., region 4.

[0060] The optical microstructure 3 does not necessarily have to be distributed throughout the entire space enclosed by the annular member 2. Instead, it can be selectively arranged in one or more specific sub-regions according to actual optical design requirements. This selectivity provides design flexibility, allowing for targeted optimization of light extraction efficiency or light emission angle. For example, the optical microstructure 3 can be placed only in the region 4 immediately adjacent to the light-emitting diode chip 1 to maximize near-field optical coupling, or the optical microstructure 3 can be placed in the edge region inside the annular member 2 to further widen the far-field light emission angle.

[0061] Setting at least one optical microstructure 3 refers to introducing an optical microstructure 3 with specific geometry and optical properties within the aforementioned defined region (region 4 and / or multiple regions 5) to alter the propagation path and emission angle of light. This can be a single or multiple combinations of optical microstructures 3, or one or more optical microstructures 3 in number. These microstructures can redistribute the light emitted from the light-emitting diode chip 1 through optical principles such as refraction, reflection, and diffraction. For example, the optical microstructure 3 can take the form of a microlens array, using its curved surface to focus or diffuse light; or it can use a micro-pyramidal array, using its inclined surface to guide light outward in a specific direction. Furthermore, it can also be a structure with periodic or non-periodic arrangement such as micropillars, micropores, or microgrooves, typically with dimensions at the micrometer or sub-micrometer level, to achieve precise control of light.

[0062] In a further preparation method of this application, the optical microstructure 3 is formed by photolithography using a photosensitive material, and the optical microstructure includes one or more of microlenses, micropyramids, and gradient refractive index microstructures.

[0063] Using photosensitive materials combined with photolithography to form optical microstructures 3 significantly improves the forming accuracy and consistency of the optical microstructures 3. Photolithography, with its high resolution and repeatability, ensures that each optical microstructure 3 can be precisely formed according to the preset geometry and size. This high precision and consistency guarantees the stability of the light control effect of the optical microstructure 3, making the widening of the light emission angle more controllable and uniform. Furthermore, by selecting one or more combinations of microlenses, micropyramids, or gradient refractive index microstructures, different optical control functions can be flexibly designed and implemented according to specific light emission angle requirements. Microlenses achieve light diffusion through refraction, micropyramids achieve light scattering through multi-faceted refraction and reflection, while gradient refractive index microstructures guide the light path through continuous refractive index changes. These structures, in conjunction with the area enclosed by the ring-shaped component, effectively and uniformly diffuse the light emitted from the chip to a wider viewing angle range, thereby significantly widening the light emission angle of the printed circuit board assembly and improving the uniformity and viewing experience of the display device.

[0064] In a third aspect of this application, a backlight module is proposed, comprising a frame, a backplate, a light guide plate, a reflector, an optical film assembly, and the aforementioned printed circuit board assembly. The frame, backplate, light guide plate, reflector, and optical film assembly together constitute the basic structure of the backlight module, working collaboratively to provide mechanical support, heat dissipation, and specific optical functions. For example, the frame is typically used to fix and support other optical components, the backplate provides mechanical support and heat dissipation, the light guide plate is used to uniformly diffuse light emitted from a point source into a surface light source, the reflector is used to improve light utilization, and the optical film assembly further optimizes light uniformity and brightness. The aforementioned printed circuit board assembly, as the light source portion of the backlight module, integrates a light-emitting diode chip 1 and a ring-shaped component 2, responsible for providing the required light source. In this backlight module, the chip 1 of the printed circuit board assembly is covered by an optical colloid 6, such as an optical colloid formed from a high-refractive-index material like silicone or epoxy resin. The main function of the optical colloid 6 is to protect the light-emitting diode chip 1 from mechanical damage, moisture and dust corrosion, and to regulate the light emission characteristics of the chip 1 to achieve a specific emission angle or light pattern. The optical colloid 6 can cover the chip 1 through various methods such as dispensing, spraying or molding.

[0065] Furthermore, the optical colloid 6 is confined within the area enclosed by the annular member 2. Here, "confinement" refers to guiding the optical colloid 6 within a specific area through physical boundaries or surface tension, preventing it from overflowing or spreading irregularly. The "area enclosed by the annular member 2" refers to the closed or semi-closed space formed by the annular member 2 on the surface of the printed circuit board. The annular member 2 can act as a physical baffle, directly blocking the flow of the colloid; alternatively, the annular member 2 can interact with the surface tension of the colloid by altering its surface wettability, such as by being hydrophilic or hydrophobic, thereby precisely controlling the shape and extent of the colloid.

[0066] This application utilizes the annular component 2 as a physical boundary or surface tension guiding structure, which can precisely confine the optical alternation 6 within a preset area, thereby effectively solving the problems of unstable adhesion and inconsistent forming of optical colloids due to the lack of structural guidance. This confinement ensures a stable and uniform contact area between the optical colloid and the printed circuit board surface, significantly enhancing the adhesion of the colloid and reducing the risk of delamination and cracking under high temperature, high humidity, or thermal cycling stress, thus improving the long-term reliability of the backlight module. Simultaneously, because the optical colloid 6 is precisely confined, the optical colloid lens structure above each chip 1 can form a highly consistent shape, height, and radius of curvature, avoiding the problem of uneven colloid forming caused by differences in leveling properties in traditional dispensing processes. This ensures that the emission angle and brightness of each pixel remain highly consistent, effectively eliminating the display "mura" phenomenon and significantly improving the uniformity and visual effect of the display device.

[0067] In a fourth aspect of this application, a display device is proposed, comprising a liquid crystal panel and a backlight module.

[0068] The liquid crystal panel (LCD) is the core component of the display device. It regulates the light passing through by controlling the arrangement of liquid crystal molecules, thereby forming an image. LCD panels can employ various technologies; for example, they can be thin-film transistor (TFT) based LCD panels, where each pixel is driven by one or more TFTs to achieve fast response and high contrast. As the output interface of the display device, the LCD panel is responsible for converting electrical signals into a visible image, and its display quality directly affects the user experience. The backlight module is a component that provides a uniform surface light source for the LCD panel and is an indispensable part of the LCD display device. The backlight module can adopt a direct-lit backlight design, where the light source (such as an LED array) is directly located below the light guide plate, providing uniform illumination; or it can adopt an edge-lit backlight design, where the light source is located on the side of the light guide plate, which guides the light uniformly to the area below the LCD panel. The main function of the backlight module is to provide sufficient and uniform brightness to ensure that the LCD panel can display images clearly and accurately. By combining the LCD panel with the backlight module described in this application, the display device of this application can effectively solve the problems of uneven display and reliability.

[0069] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A printed circuit board assembly, characterized in that, Includes a printed circuit board and at least one light-emitting diode chip assembly; The light-emitting diode chip assembly includes a chip and at least one annular member; the chip is disposed on the surface of the printed circuit board and is connected to the circuit of the printed circuit board; the annular member is disposed on the surface of the printed circuit board around the central axis of the chip and is coaxial with the central axis.

2. The printed circuit board assembly according to claim 1, characterized in that, At least one optical microstructure is provided in at least one of the regions enclosed by the annular member and the chip, and in at least one region enclosed by the adjacent annular member, the optical microstructure being capable of widening the light emission angle.

3. The printed circuit board assembly according to claim 2, characterized in that, The optical microstructure includes one or more of the following: microlenses, micropyramids, and gradient refractive index microstructures formed from photosensitive materials.

4. The printed circuit board assembly according to claim 1 or 2, characterized in that, The ring-shaped component includes one or more of the following: circles and regular polygons.

5. The printed circuit board assembly according to claim 1 or 2, characterized in that, The height of the annular component is 5-10 μm; and / or The width of the annular component is 10-50 μm; and / or The spacing between the annular components is 0.1-1 mm.

6. A method for manufacturing a printed circuit board assembly as described in claim 1, characterized in that, include: Provide printed circuit boards; At least one light-emitting diode (LED) chip is disposed on the surface of the printed circuit board, and at least one annular member is disposed around the central axis of each LED chip, with each annular member being coaxial with the central axis around which it is disposed.

7. The preparation method according to claim 6, characterized in that, Within the area enclosed by the annular member surrounding the central axis of each of the light-emitting diode chips, at least one optical microstructure is disposed in at least one region.

8. The preparation method according to claim 7, characterized in that, The optical microstructure is formed using photosensitive materials through photolithography. The optical microstructure includes one or more of the following: microlenses, micropyramids, and gradient refractive index microstructures.

9. A backlight module, characterized in that, It includes a frame, a backplate, a light guide plate, a reflector, an optical film assembly, and a printed circuit board assembly as described in any one of claims 1-5; The chips of the printed circuit board assembly are covered with an adhesive, which is confined within the area enclosed by the annular member.

10. A display device, characterized in that, It includes a liquid crystal panel and the backlight module as described in claim 9.

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