An ultra-thin liquid crystal module based on COF packaging technology and a manufacturing method thereof

Abstract

The application discloses a kind of ultra-thin liquid crystal module based on COF packaging technology and its manufacturing method, the module includes liquid crystal display panel, backlight module, middle frame and COF packaging structure, backlight module is equipped with integrated cavity, it is filled with optical matching filling body with the difference of refractive index and light guide plate in ±0.02 inside, to optimize the optical transmission path of truncated reconstruction.Elastic bending after driving chip is contained in the filling body, and be gapless package, so that the overall thickness of bending area is equal to the gap thickness between liquid crystal display panel and backlight module.The application integrates chip entity space and optical space as one, aims at solving the bulge formed by the thickness of driving chip after reverse folding, resulting in the increase of module overall thickness and the decrease of circuit reliability, realizes module ultra-thin, with the aid of optical matching material and buffer structure, display quality and structural reliability are considered.

Description

Technical Field

[0001] This invention relates to the field of liquid crystal display technology, and more specifically, to an ultra-thin liquid crystal module based on COF packaging technology and its manufacturing method. Background Technology

[0002] With the rapid development of consumer electronics, portable electronic devices such as smartphones, tablets, and laptops are placing increasingly stringent demands on display modules—thinner, lighter, with narrower bezels, and larger display areas. As one of the core components of these devices, the thickness and bezel width of the LCD module directly determine the design space and market competitiveness of the entire product.

[0003] COF (Chip on Film) packaging technology is an advanced packaging method that directly bonds the driver chip onto a flexible thin-film substrate. Compared to the traditional COG (Chip on Glass) technology, COF technology transfers the driver chip from the LCD glass panel to a flexible film, thereby effectively reducing the width of the bottom bezel of the panel and becoming a key technology path for realizing ultra-narrow bezel LCD display modules. Currently, COF packaging technology has been widely used in mid-to-high-end display products, but it still faces several technical bottlenecks in achieving ultra-thinness.

[0004] In existing COF-packaged LCD modules, the driver chip is bonded to a flexible thin-film substrate. One end of the flexible thin-film substrate is connected to the bonding area of ​​the LCD glass, and the other end is connected to the printed circuit board. To achieve an ultra-thin overall LCD module, the flexible thin-film substrate is usually bent so that it folds back to the back of the LCD glass. However, this structural design has a difficult technical problem to overcome: the driver chip itself has a certain physical thickness (usually 0.2mm-0.4mm). When the flexible thin-film substrate is folded back, the driver chip protrudes from the surface of the flexible thin-film substrate, forming a local "bulge" at the chip location. This bulge not only increases the overall thickness of the LCD module, but more importantly, during the folding process, the stress concentration at the connection between the chip and the thin-film substrate can easily lead to circuit breakage or chip peeling, seriously affecting the reliability and yield of the product.

[0005] To address the aforementioned issues, Chinese invention patent application CN105278185A, entitled "A Liquid Crystal Display Screen-Gate COF Structure Assembly and a Liquid Crystal Display Device," proposes a COF bending and storage solution. This solution connects one end of the gate COF structure to the side of the liquid crystal screen and bends it towards the back of the screen, while the other end is connected to the back of the screen. The COF structure is housed within a space formed by the liquid crystal screen, backlight module, and front frame. While this solution protects the COF structure from external damage to some extent, it does not solve the problem of increased thickness caused by the protruding driver chip—the height of the storage space must be greater than the overall thickness of the COF structure (including the height of the driver chip). This means that the thickness of the backlight module or the front frame needs to be increased accordingly, thus limiting the possibility of further development of ultra-thin liquid crystal display devices.

[0006] Another Chinese invention patent application, CN110133929A, entitled "Array Substrate and Manufacturing Method Thereof, Display Panel and Display Module," proposes a solution that increases the overall thickness of the bonding area by setting a gate line bump layer on the same layer as the gate lines and a data line bump layer on the same layer as the data lines, thereby improving the pull-out force of the COF. However, this solution increases the complexity of the array substrate manufacturing process and does not provide an effective solution to the bulging problem after the COF is folded back.

[0007] Furthermore, Chinese invention patent application CN102890348A, entitled "A COF baseband and its manufacturing method, and a liquid crystal display module," discloses a technical solution of setting light-transmitting alignment marks on both sides of the COF baseband connection pins, aiming to improve the alignment accuracy of the bonding between the COF baseband and the liquid crystal glass. Although this solution improves the operability of the bonding process, it also fails to address the core thickness issue in ultra-thin designs.

[0008] In summary, existing LCD modules based on COF packaging technology generally face the technical challenge of increased thickness and decreased circuit reliability due to the bulge caused by the driver chip after folding, when achieving ultra-thin designs. How to effectively eliminate or accommodate the bulge height of the driver chip after folding, while maintaining the narrow bezel advantage of COF packaging, to achieve a truly ultra-thin LCD module, while ensuring product reliability and manufacturing yield, is a technical problem that needs to be solved by those skilled in the art. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the present invention aims to provide an ultra-thin liquid crystal module based on COF packaging technology and its manufacturing method. The invention aims to solve a core technical challenge faced by existing COF-based liquid crystal modules in achieving ultra-thin designs: after the driver chip is folded back on the flexible thin-film substrate, its physical thickness causes a local "bulge" in the bending area. This bulge not only directly increases the overall thickness of the module, limiting the potential for thinner and lighter products, but also causes severe stress concentration in the bending area, easily leading to circuit breakage on the flexible substrate or driver chip peeling, seriously damaging the product's structural reliability and production yield. Existing solutions either increase the accommodating space to accommodate the bulge, failing to eliminate the thickness increase at its root; or focus on improving the bonding process, avoiding the structural and optical conflicts in the folded area. Therefore, the key technical challenge of this invention is to fundamentally "digest" the driver chip's bulge height from a structural design perspective while maintaining the narrow bezel advantage of COF, and simultaneously resolve the optical defects introduced by the slotting, thereby achieving a balance between ultra-thinness and high reliability without increasing module thickness or sacrificing display quality.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] An ultra-thin liquid crystal module based on COF packaging technology includes a liquid crystal display panel, a backlight module, a mid-frame, and a COF packaging structure. The backlight module is disposed on the back side of the liquid crystal display panel and includes a reflective sheet, a light guide plate, and an optical film group stacked sequentially. The mid-frame is used to support the backlight module and fix the liquid crystal display panel. The COF packaging structure includes a flexible thin film substrate and a driving chip bonded to the flexible thin film substrate. A first end of the flexible thin film substrate is electrically connected to the bonding area of ​​the liquid crystal display panel, and a second end of the flexible thin film substrate is bent toward the back side of the liquid crystal display panel and extends to the back side of the backlight module.

[0012] The backlight module is provided with at least one integrated cavity, which is a groove formed from the surface of the reflective sheet away from the light guide plate, through the reflective sheet and extending into the interior of the light guide plate.

[0013] In designing the integrated cavity, this invention intentionally avoids the light-guiding dot area on the bottom surface of the light guide plate. In one embodiment, the bottom projection area of ​​the integrated cavity corresponds to the bottom surface of the light guide plate without any light-guiding dots, while the surrounding area has normally distributed light-guiding dots. In another embodiment, the integrated cavity is entirely disposed in the dot-free area of ​​the light guide plate. In this way, the processing and filling of the integrated cavity will not damage the dot structure that was not originally present underneath, thus fundamentally avoiding local optical anomalies caused by missing or residual dots.

[0014] The integrated cavity is filled with an optical matching filler, the difference between the refractive index of the optical matching filler and the refractive index of the light guide plate is within ±0.02, which is used to reconstruct the truncated optical transmission path. The refractive index is the refractive index measured at 25°C using a light source with a wavelength of 589nm.

[0015] The integrated cavity is filled with an optically matched filler, which forms optical coupling with at least the sidewalls and bottom surface of the integrated cavity. Compared to an unfilled cavity, the optically matched filler significantly reduces the abrupt changes in the optical interface introduced by the presence of the integrated cavity. By providing an optical medium similar to the material of the light guide plate body, it greatly reduces the unintended reflection and scattering of light at the cavity interface, thereby optimizing and reconstructing the optical transmission path of the light guide plate in the integrated cavity region.

[0016] The driving chip is housed in the optical matching filler in the integrated cavity after the flexible thin film substrate is bent; the driving chip is completely embedded in the integrated cavity, such that the maximum thickness of the bending area of ​​the COF package structure in the direction perpendicular to the liquid crystal display panel is equal to the assembly gap thickness between the liquid crystal display panel and the backlight module.

[0017] Through the above structural design, the present invention achieves the following synergistic technical effects: the driving chip is completely housed inside the backlight module body, integrating the originally separate and conflicting "chip physical space" and "optical transmission space" into a single integrated functional cavity; with the help of an optical adhesive filler with precisely matched refractive index, the optical transmission path of the light guide plate, which was interrupted by the slotting, is optically reconstructed without gaps, eliminating optical defects such as light scattering, light leakage, and shadows that are usually caused by foreign matter or gaps, ensuring the optical continuity of the light guide plate in this area; at the same time, after the optical matching filler is cured, it forms a structural bridging layer connecting the driving chip and the side wall of the light guide plate cavity, making the integrated cavity a localized optical-mechanical buffer node that integrates optical repair, structural accommodation, and stress buffering; thus, the present invention solves the thickness bottleneck and stress damage risk caused by the reverse folding protrusion of the driving chip without sacrificing the optical performance of the backlight module or increasing the overall interlayer gap thickness of the module.

[0018] Furthermore, the depth of the integrated cavity is not less than the thickness of the driver chip to ensure that the driver chip is fully accommodated.

[0019] Furthermore, the optical matching filler is made of a transparent photocurable viscoelastic material, which forms a gapless optical coupling with the sidewalls of the integrated cavity and the surface of the driving chip, and provides stress buffering and encapsulation protection for the driving chip. The difference between the refractive index of the optical matching filler and the refractive index of the light guide plate body material is controlled within ±0.02, preferably with a refractive index of 1.485-1.495 after curing. Through the control of the above material parameters, the optical matching filler can not only form a continuous body with the light guide plate without an optical interface, but also provide continuous stress buffering and vibration damping for the driving chip through its viscoelasticity.

[0020] The optical matching filler, composed of a transparent photocurable viscoelastic material with a refractive index matching that of the light guide plate, fills the integrated cavity to form optical coupling with at least the sidewalls of the integrated cavity and the surface of the driving chip. Compared to an unfilled cavity, the optical matching filler significantly reduces the abrupt optical interface changes introduced by the presence of the integrated cavity. By providing an optical medium similar to the material of the light guide plate body, it greatly reduces unintended reflections and scattering of light at the cavity interface, thereby optimizing and reconstructing the optical transmission path of the light guide plate in the integrated cavity region.

[0021] To achieve optical matching, the optical matching filler must be made of a transparent, UV-curable viscoelastic material, and its refractive index after curing is precisely designed to match the optical parameters of the selected light guide plate material. For example, when the light guide plate is made of polymethyl methacrylate (PMMA) with a refractive index of approximately 1.49, the optical matching filler uses a special acrylate-based UV-curable adhesive with a cured refractive index of 1.485-1.495. Within this range, Fresnel reflection at the filler-light guide plate interface is almost eliminated, achieving optimal optical path reconstruction. Furthermore, the cured material must also possess viscoelasticity (Young's modulus in the range of 10-100 MPa) and a certain thermal conductivity (thermal conductivity ≥0.2 W / m·K) to simultaneously meet the engineering requirements of stress buffering and auxiliary heat dissipation.

[0022] Furthermore, the bottom surface of the integrated cavity is provided with an optically transparent buffer layer, which is disposed between the bottom surface of the integrated cavity and the optical matching filler. The driving chip is accommodated in the optical matching filler and contacts the upper surface of the buffer layer.

[0023] Furthermore, the buffer layer forms a gapless optical coupling with the bottom surface of the integrated cavity and the optical matching filler, and the difference between the refractive index of the buffer layer and the refractive index of the light guide plate is within ±0.02.

[0024] Furthermore, the bending area of ​​the flexible thin film substrate in the COF packaging structure is covered with a protective adhesive layer. The protective adhesive layer wraps around the edge of the driver chip and the junction between the driver chip and the flexible thin film substrate to disperse bending stress, provide sealing protection, and prevent the hard edges from scratching adjacent components.

[0025] Furthermore, the projection of the integrated cavity onto the horizontal plane overlaps the projection of the driving chip onto the horizontal plane, and the opening area of ​​the integrated cavity is larger than the bottom area of ​​the driving chip, in order to compensate for alignment deviations during assembly and improve production yield. Additionally, a preset gap is left between the bottom surface (dot surface) of the light guide plate and the reflector outside the opening area of ​​the integrated cavity to maintain the optical function of the light guide plate dots in that area, which are not damaged by the integrated cavity.

[0026] A method for manufacturing the above-mentioned ultra-thin liquid crystal module includes the following steps:

[0027] Step S1: Provide a liquid crystal display panel, a backlight module, and a mid-frame; wherein, on the side surface of the backlight module facing the liquid crystal display panel, at least one integrated cavity is pre-processed to form an integral cavity by means of laser engraving, CNC milling, or injection molding; the integrated cavity penetrates the reflective sheet and extends into the interior of the light guide plate; and when the integrated cavity is processed by laser engraving or CNC milling, its processing range is precisely controlled outside the dot area of ​​the light guide plate, or, in the local area where the integrated cavity is provided, the bottom surface of the light guide plate is not provided with light guide dots at the corresponding position;

[0028] Step S2: The bonding area of ​​the liquid crystal display panel is bonded to the first end of the flexible thin film substrate in the COF packaging structure by pressing with anisotropic conductive adhesive.

[0029] Step S3: Apply or inject liquid photocurable viscoelastic material with a refractive index difference of ±0.02 from that of the light guide plate into the integrated cavity; then bend the second end of the flexible thin film substrate in the COF packaging structure toward the back of the liquid crystal display panel, so that the driving chip is aligned and gradually approaches the integrated cavity; then completely place the driving chip into the photocurable viscoelastic material in the integrated cavity, so that the driving chip is wetted by the photocurable viscoelastic material. The placement process of the driving chip is carried out at a slow speed of 0.1-1 mm / s until the bottom surface of the driving chip contacts the bottom surface of the integrated cavity or the buffer layer, and after contact, apply a pressure of 0.05-0.2 MPa, which does not exceed the driving chip's tolerance limit, and maintain this pressure until the photocurable viscoelastic material cures; finally, after the photocurable viscoelastic material has cured, the driving chip is embedded and fixed in the formed optical matching filler to form a gapless optical coupling.

[0030] Step S4: Connect the second end of the COF package structure to the external circuit board;

[0031] Step S5: Assemble and fix the liquid crystal display panel, the backlight module, and the mid-frame to securely house the driver chip within the integrated cavity.

[0032] Optionally, before chip placement in step S1 or step S3, a buffer layer may be provided at the bottom of the integrated cavity.

[0033] By adopting the above technical solution, the beneficial effect of the present invention is to achieve a truly ultra-thin structure:

[0034] 1. By creating an integrated cavity within the thickness direction of the backlight module, the driver chip is completely "submerged" into the backlight module body, allowing its protrusion height to be absorbed by the solid thickness of the light guide plate and reflector. Ultimately, in the corresponding area of ​​the integrated cavity, the overall thickness of the COF bending area is equal to the inherent assembly gap thickness between the LCD panel and the backlight module. This overcomes the physical limit imposed by the driver chip thickness on the overall module thickness, eliminating the need to increase module thickness to gain space for the driver chip, as is required in existing solutions.

[0035] 2. Traditionally, slotting in a light guide plate inevitably disrupts the continuity of the optical path, leading to point-like light leakage or shadows. This invention seamlessly reconstructs the interrupted optical transmission path by filling it with an optically matched filler whose refractive index precisely matches the light guide plate, making the slotted area optically "invisible." When light passes through the filled area, the refraction and reflection states remain almost unchanged, effectively avoiding various optical anomalies caused by the presence of the cavity, ensuring the uniformity of light output and high-quality display effect of the backlight module.

[0036] 3. Significantly Improved Reliability and Production Yield in Bending Areas: The driver chip is embedded and fixed within a flexible protection system composed of a viscoelastic optical matching filler and a buffer layer, with its connection to the substrate reinforced by a protective adhesive layer. This multi-layered flexible protection structure disperses bending stress from localized concentration points to the entire bonding interface, greatly reducing the risk of circuit breakage and chip peeling, thus improving the reliability of the bending area. Simultaneously, the opening area of ​​the integrated cavity is larger than the chip's bottom area, providing ample tolerance space for assembly alignment, thereby improving production efficiency and assembly yield.

[0037] 4. The manufacturing method of this invention uses mature processes such as laser engraving, CNC milling or mold-integrated molding to process the integrated cavity. The chip can be embedded by dispensing and bending. It is highly compatible with the existing COF production process, with low modification cost, high operability, and easy to achieve large-scale and automated production. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of the structure of the liquid crystal module in Embodiment 1 of the present invention.

[0039] Figure 2 This is a schematic diagram of the structure of the reflector and light guide plate combined with the integrated cavity.

[0040] Figure 3 A schematic diagram of the structure for protecting the adhesive layer in conjunction with the driver chip.

[0041] In the figure: 1-LCD panel, 2-backlight module, 21-reflective sheet, 22-light guide plate, 23-optical film group; 3-middle frame; 4-COF packaging structure, 41-flexible thin film substrate, 42-driver chip; 5-integrated cavity; 6-buffer layer; 7-protective adhesive layer; 8-optical matching filler. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the following description will be provided in conjunction with the appendix. Figure 1 To be continued Figure 3 The technical solution of the present invention will be clearly and completely described in conjunction with specific embodiments.

[0043] In the description of this invention, it should be understood that the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0044] Example 1

[0045] This embodiment provides an ultra-thin liquid crystal module based on COF packaging technology. This module can be widely used in portable electronic devices such as smartphones, tablets, and laptops to achieve ultra-thin and narrow bezel designs for display modules.

[0046] The ultra-thin liquid crystal module based on COF packaging technology in this embodiment mainly includes: a liquid crystal display panel 1, a backlight module 2, a middle frame 3, a COF packaging structure 4, and key integrated cavity 5 and optical matching filler 8.

[0047] The liquid crystal display panel 1 serves as the core component for image display, with a backlight module 2 sequentially arranged on its back side. The backlight module 2 provides a uniform surface light source for the liquid crystal display panel 1 and typically includes a reflective sheet 21, a light guide plate 22, and an optical film assembly 23 stacked sequentially. The reflective sheet 21, located at the bottom layer, reflects light emitted from the bottom surface of the light guide plate 22 back to the light guide plate 22, improving light utilization. The light guide plate 22 converts the side-lit light source into a uniform surface light source. The optical film assembly 23 typically consists of multiple layers of optical films, such as diffusion films and brightness enhancement films, to further improve the uniformity and brightness of the emitted light. The mid-frame 3 serves as a structural support, supporting the backlight module 2 and securing the liquid crystal display panel 1 to the front of the backlight module 2 using light-shielding tape. The mid-frame 3 is typically made of metal or high-strength plastic, and its shape and structure can be customized according to the overall product design requirements.

[0048] The COF packaging structure 4 is a key component for achieving narrow bezels and ultra-thin designs. This COF packaging structure 4 includes a flexible thin-film substrate 41 and a driver chip 42 bonded to the flexible thin-film substrate 41. The flexible thin-film substrate 41 is made of a polymer thin-film material with good flexibility and heat resistance, such as polyimide, and its surface is covered with fine metal wires. The driver chip 42 is electrically connected to the leads on the flexible thin-film substrate 41 via thermoforming or other methods to provide driving signals to the liquid crystal display panel 1. The first end of the flexible thin-film substrate 41 is electrically connected to the bonding area of ​​the liquid crystal display panel 1. Preferably, the bonding area of ​​the liquid crystal display panel 1 and the first end of the flexible thin-film substrate 41 are bonded together using anisotropic conductive adhesive to achieve reliable electrical conduction and physical fixation of the micro-electrode pins between them.

[0049] To achieve ultra-thinness in the module, the COF packaging structure 4 is bent in this invention. Specifically, the second end of the flexible thin-film substrate 41 is bent from the front side of the liquid crystal display panel 1 to its back side, and further extends to the back side of the backlight module 2, ultimately connecting to an external circuit board (typically a main printed circuit board, PCB) located behind or to one side of the backlight module 2. The external circuit board provides control signals and power to the driver chip 42 and the liquid crystal display panel 1 through the flexible thin-film substrate 41.

[0050] To address the issue described in the background art where the driver chip 42 forms a "bulge" after bending, leading to an increase in overall thickness, this invention provides at least one integrated cavity 5 on the backlight module 2. This integrated cavity 5 is a groove formed by starting from the surface of the reflective sheet 21 away from the light guide plate 22, penetrating the reflective sheet 21, and extending into the interior of the light guide plate 22. The size and position of this integrated cavity 5 are designed such that when the flexible thin-film substrate 41 is bent, the driver chip 42 is precisely accommodated within the integrated cavity 5. Through this structural design, the driver chip 42 is completely embedded within the integrated cavity 5, ensuring that the maximum thickness of the bending area of ​​the COF package structure 4 in the direction perpendicular to the liquid crystal display panel 1 is equal to the assembly gap thickness between the liquid crystal display panel 1 and the backlight module 2. In other words, the physical thickness of the driver chip 42 is completely accommodated by the integrated cavity 5 on the backlight module 2, and no longer occupies the design gap between the liquid crystal display panel 1 and the backlight module 2. Thus, without increasing or even further reducing the gap, a truly ultra-thin module structure is achieved.

[0051] More specifically, the integrated cavity 5 is disposed on the surface of the backlight module 2 facing the liquid crystal display panel 1. To ensure that the driver chip 42 can be completely recessed into the integrated cavity 5 without pushing up the liquid crystal display panel 1, the depth of the integrated cavity 5 is not less than the thickness of the driver chip 42. Typically, the thickness of the driver chip 42 is between 0.2mm and 0.4mm, and the depth of the integrated cavity 5 should be set accordingly, with a certain safety margin. The projection of the integrated cavity 5 on the horizontal plane covers the projection of the driver chip 42 on the horizontal plane, and the opening area of ​​the integrated cavity 5 is larger than the bottom area of ​​the driver chip 42, so that the driver chip 42 can be smoothly placed into the slot during assembly, reducing the alignment accuracy requirements and improving the assembly yield.

[0052] Furthermore, the integrated cavity 5 is filled with an optical matching filler 8, which is made of a transparent and thermally conductive viscoelastic material. The optical matching filler forms a gapless optical coupling with the sidewall of the integrated cavity 5 and the surface of the driving chip 42, so that the integrated cavity, the optical matching filler and the driving chip together constitute a localized optical-mechanical integrated buffer node.

[0053] In this embodiment, the optical matching filler 8 is a UV-curable transparent optical adhesive whose refractive index precisely matches that of the main material of the light guide plate 22 (such as PMMA, with a refractive index of approximately 1.49). After curing, the optical adhesive forms a viscoelastic body with a refractive index of 1.485-1.495 and a light transmittance greater than 95%. This optical adhesive is viscoelastic and has a low modulus after curing, providing stress buffering and mechanical protection for the driver chip 42. When the flexible thin-film substrate 41 is bent, the driver chip 42 is positioned directly opposite the integrated cavity 5, completely immersed in the liquid optical adhesive, and after curing, is seamlessly embedded and fixed inside the optical matching filler 8. This optical adhesive simultaneously forms complete optical coupling with the sidewalls and bottom surface of the integrated cavity 5, seamlessly reconstructing the light guide path interrupted by the integrated cavity 5, ensuring that the light emission uniformity in this area remains unaffected.

[0054] In this embodiment, the integrated cavity 5 is specifically disposed within the internal structure of the backlight module 2. Combined with the stacked structure of the backlight module 2, the integrated cavity 5 penetrates the reflective sheet 21 and extends into the interior of the light guide plate 22. That is, the bottom of the integrated cavity 5 is located within the body material of the light guide plate 22, rather than being a through-hole penetrating the light guide plate 22. This design maximizes the preservation of the structural integrity and original optical transmission characteristics of the light guide plate 22, avoiding the formation of through-holes due to excessively deep slots, which could lead to point-like light leakage or uneven brightness optical defects. The refractive index of the optical matching filler 8 matches the refractive index of the light guide plate 22, used to reconstruct the interrupted optical transmission path. The integrated cavity 5 can be formed by processing the reflective sheet 21 and the light guide plate 22 separately before assembling the backlight module 2, and then stacking and assembling them. The depth of the integrated cavity 5 is sufficient to accommodate the driver chip 42 and part of the optical matching filler 8. The driver chip 42 is completely embedded in the optical matching filler 8, and an optical adhesive can be covered on top until the integrated cavity 5 is filled. Since the refractive index of the optical adhesive 8 matches that of the light guide plate 22, the light guide path that was originally cut off by the cavity is seamlessly reconstructed, and the light can pass through the area with minimal loss, avoiding point-like light leakage and shadows.

[0055] To further improve product reliability and protect the driver chip 42 from stress damage during bending and subsequent use, this embodiment also adds multiple protective structures.

[0056] First, at the bottom of the integrated cavity 5, i.e., on the milled surface of the light guide plate 22, an optically transparent buffer layer 6 is also provided. The buffer layer 6 is positioned between the bottom surface of the integrated cavity 5 and the optical matching filler 8. The driving chip 42 is housed within the optical matching filler 8 and contacts the upper surface of the buffer layer 6 to provide appropriate pre-pressure, preventing the driving chip 42 from shifting or resonating when the module is subjected to vibration or impact, while also avoiding stress concentration caused by hard contact. The buffer layer 6 uses a transparent, highly flexible UV-curable optical adhesive, whose cured Young's modulus is much lower than that of the optical matching filler 8, and its refractive index is also matched with that of the light guide plate 22. Through this design, the buffer layer 6, while providing stress buffering, also serves as part of the optical path, together with the optical matching filler 8 and the light guide plate 22 body, constructing a complete and continuous optical transmission path, achieving a true unity of optical repair and mechanical buffering. After curing, the optical matching filler 8 seamlessly bonds the driver chip 42, the cavity sidewall of the light guide plate 22, and the opening edge of the reflector 21 together. This structure optimizes the optical path and provides comprehensive stress buffering and encapsulation protection for the driver chip 42. Thus, the integrated cavity 5, the optical matching filler 8, and the buffer layer 6 work together to form a functionally separate but synergistic optical-mechanical buffer node.

[0057] Secondly, a protective adhesive layer 7 is applied to the bending area of ​​the flexible thin-film substrate 41. This protective adhesive layer 7 covers the edge of the driver chip 42 and the junction between the driver chip 42 and the flexible thin-film substrate 41. This structure serves several purposes: First, it strengthens the bonding strength between the driver chip 42 and the flexible thin-film substrate 41, disperses the stress in the bending area, and effectively prevents the flexible thin-film substrate 41 from experiencing circuit breakage or chip peeling due to internal stress or external vibration after bending. Second, the protective adhesive layer 7 seals the exposed metal parts such as chip pins, providing insulation protection against moisture, dust, and corrosion. Third, the smooth adhesive surface prevents the hard edges of the driver chip 42 from directly rubbing or scratching the back of the opposite liquid crystal display panel 1 or other components during assembly or use, thus avoiding secondary damage.

[0058] With the above structure, the driving chip 42 is completely embedded in the integrated cavity 5 of the backlight module 2, and its protrusion height does not overlap into the gap between the liquid crystal display panel 1 and the backlight module 2, thus compressing the interlayer gap to an extremely small size. At the same time, the optical matching filler 8 makes the slotted area appear as part of the light guide plate body, and the uniformity of the image is not affected. This structure achieves a balance between ultra-thinness and high reliability.

[0059] In another preferred embodiment, a buffer layer 6, such as a thermally conductive silicone pad, is first disposed at the bottom of the integrated cavity 5. Then, an optical matching filler 8 is filled into the remaining space of the cavity above the buffer layer 6. The driver chip 42 is embedded within the filler 8 and forms a flexible optical coupling with the light guide plate 22 through the filler 8 and the buffer layer 6. This design further enhances impact resistance.

[0060] In an optimal implementation of this embodiment, the depth of the integrated cavity 5, the thickness of the driving chip 42, and the thicknesses of each layer of the flexible thin film substrate 41 and the optical film group 23 are precisely designed to match each other, so that in the final assembled state, the maximum thickness of the bending area of ​​the COF packaging structure 4 in the direction perpendicular to the liquid crystal display panel 1 is exactly equal to the assembly gap thickness between the liquid crystal display panel 1 and the backlight module 2, thereby maximizing the utilization of the gap space while ensuring no interference.

[0061] Example 2

[0062] This embodiment provides a method for manufacturing an ultra-thin liquid crystal module based on COF packaging technology, used to manufacture the ultra-thin liquid crystal module as described in Embodiment 1. The method specifically includes the following steps:

[0063] Step S1: Material preparation and integrated cavity processing. A liquid crystal display panel 1, a backlight module 2, and a mid-frame 3 are provided. During the manufacturing process of the backlight module 2, before its reflector 21 and light guide plate 22 are laminated, a CNC precision milling process is used to mill a groove of a certain depth and opening area at a predetermined surface position on the light guide plate 22, and the corresponding position of the reflector 21 is opened to form an integrated cavity 5 that penetrates the reflector 21 and extends into the interior of the light guide plate 22. After processing, the cavity is cleaned, and a layer of liquid high thermal conductivity gel (thermal conductivity ≥1.5 W / m·K) of a predetermined thickness is coated on its bottom. After curing, a buffer layer 6 with a buffering function is formed. Alternatively, the buffer layer 6 can also be a precision-die-cut thermally conductive silicone pad with high thermal conductivity, which is attached to the bottom of the cavity using thermally conductive double-sided adhesive.

[0064] In the manufacturing process of the light guide plate 22, a chip accommodating area is first designed and defined according to the bonding position of the driver chip 42. The bottom surface of the light guide plate 22 within this chip accommodating area is free of light-guiding dots. When using laser engraving, the laser processing boundary is strictly located within this dot-free area, resulting in a smooth plane at the bottom of the engraved integrated cavity 5, free from any cut or damaged light-guiding dots. Once the refractive index-matching optical filler 8 fills this integrated cavity 5, the propagation path of light within this area is essentially restored. Furthermore, because there are no additional dot disturbances at the bottom, no unexpected light emission phenomena occur, ensuring backlight uniformity.

[0065] Step S2: Panel bonding with COF. Unwind the roll-to-roll COF packaging structure 4 and precisely bond the first end of the flexible thin film substrate 41 to the electrode bonding area of ​​the liquid crystal display panel 1 using an ACF hot-pressing process.

[0066] Step S3: Dispensing and Chip Placement & Curing. A calculated volume of liquid UV-curable optical adhesive is injected into the integrated cavity 5 using a precision dispensing machine, with the dispensing amount precisely controlled to 105%-110% of the target filling volume. Subsequently, a high-precision six-axis robotic arm grasps and controls the flexible thin-film substrate 41 to bend towards its back side. The robotic arm is equipped with a vision alignment system to ensure precise alignment of the driver chip 42 with the center position of the integrated cavity 5. During placement, its speed is adjustable within the range of 0.1-1 mm / s, preferably 0.5 mm / s. When the bottom surface of the driver chip 42 makes slight contact with the bottom surface of the integrated cavity 5, the robotic arm switches to pressure control mode, applying a constant micro-pressure of 0.1 MPa and maintaining this state until the photocurable viscoelastic material cures to form the optically matched filler 8, thus sealing the driver chip 42 seamlessly within the integrated cavity 5.

[0067] Step S4: Lead out the second end of the flexible thin film substrate 41, which has been encapsulated with the chip, and connect it to the main printed circuit board through ACF pressing or connector insertion to establish an electrical connection.

[0068] Step S5: Finally, assemble the LCD panel 1, backlight module 2, and mid-frame 3, and use light-shielding adhesive to fix the panel, completing the fabrication of the entire ultra-thin LCD module. At this point, the driver chip 42 is completely housed within the integrated cavity, and the module as a whole has an ultra-thin and flat appearance.

[0069] Alternative implementation methods

[0070] In the above embodiments, the integrated cavity 5 is disposed on the light guide plate 22 of the backlight module 2, but the scope of protection of the present invention is not limited thereto. It is understood that those skilled in the art can modify and replace the above embodiments according to the stacking architecture and process conditions of specific products.

[0071] For example, in another alternative embodiment, the integrated cavity 5 can penetrate the reflective sheet 21 and the light guide plate 22 to form a through hole, and be closed below the through hole by the metal back plate of the backlight module 2, with the driving chip 42 housed within the through hole cavity. This solution can accommodate a thicker driving chip, but requires additional consideration in optical processing. Alternatively, if the middle frame 3 is made of a high-strength material and has sufficient thickness at the corresponding location, the integrated cavity 5 can also be disposed on the side surface of the middle frame 3 facing the liquid crystal display panel 1. Any equivalent transformations or modifications made based on the core inventive concept of this invention—namely, "to accommodate the bent driving chip by providing a recessed structure on the existing stacked components between the liquid crystal display panel and the backlight module, so as to avoid increasing the overall gap thickness of the module"—should fall within the protection scope of the claims of this invention.

[0072] In the above embodiments, the optical matching filler 8 is described as a single material. However, those skilled in the art will understand that, as an alternative, the optical matching filler 8 may also consist of two or more sub-layers with different functions: for example, an optical coupling layer with extremely high refractive index matching can be used to cover the cavity sidewalls and bottom surface, and then another filling layer, primarily for thermal conductivity or stress buffering, can be filled inside it. This layered filling structure can also achieve the technical effect of reconstructing the optical transmission path and embedding the driver chip.

[0073] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0074] In this invention, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," "link," and "fix" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any ordinary changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. An ultra-thin liquid crystal module based on COF packaging technology, characterized in that, include: LCD display panel (1); A backlight module (2) is disposed on the back side of the liquid crystal display panel (1); The middle frame (3) is used to support the backlight module (2) and fix the liquid crystal display panel (1). COF packaging structure (4) includes a flexible thin film substrate (41) and a driving chip (42) bonded to the flexible thin film substrate (41). The first end of the flexible thin film substrate (41) is electrically connected to the bonding area of ​​the liquid crystal display panel (1), and the second end of the flexible thin film substrate (41) is bent toward the back side of the liquid crystal display panel (1) and extends to the back side of the backlight module (2). The backlight module (2) is provided with at least one integrated cavity (5). The backlight module (2) includes a reflective sheet (21), a light guide plate (22), and an optical film group (23) stacked in sequence. The integrated cavity (5) is a groove formed from the surface of the reflective sheet (21) away from the light guide plate (22), through the reflective sheet (21), and extending into the interior of the light guide plate (22). The integrated cavity (5) is filled with an optical matching filler (8), the difference between the refractive index of the optical matching filler (8) and the refractive index of the light guide plate (22) is within ±0.02, and is used to reconstruct the truncated optical transmission path. The refractive index is the refractive index measured at 25°C using a light source with a wavelength of 589nm. The driving chip (42) is accommodated in the optical matching filler (8) in the integrated cavity (5) after the flexible thin film substrate (41) is bent. The driving chip (42) is completely embedded in the integrated cavity (5), so that the maximum thickness of the bending area of ​​the COF package structure (4) in the direction perpendicular to the liquid crystal display panel (1) is equal to the assembly gap thickness between the liquid crystal display panel (1) and the backlight module (2).

2. The ultra-thin liquid crystal module based on COF packaging technology according to claim 1, characterized in that, The depth of the integrated cavity (5) is not less than the thickness of the driving chip (42).

3. The ultra-thin liquid crystal module based on COF packaging technology according to claim 2, characterized in that, The optical matching filler (8) is made of a transparent, thermally conductive viscoelastic material, which forms a gapless optical coupling with the sidewall of the integrated cavity (5) and the surface of the driving chip (42).

4. The ultra-thin liquid crystal module based on COF packaging technology according to claim 1, characterized in that, The bottom surface of the integrated cavity (5) is also provided with an optically transparent buffer layer (6). The buffer layer (6) is disposed between the bottom surface of the integrated cavity (5) and the optical matching filler (8). The driving chip (42) is accommodated in the optical matching filler (8) and contacts the upper surface of the buffer layer (6).

5. The ultra-thin liquid crystal module based on COF packaging technology according to claim 4, characterized in that, The buffer layer (6) forms a gapless optical coupling with the bottom surface of the integrated cavity (5) and the optical matching filler (8). The difference between the refractive index of the buffer layer (6) and the refractive index of the light guide plate (22) is also within ±0.

02.

6. The ultra-thin liquid crystal module based on COF packaging technology according to claim 1, characterized in that, The flexible thin film substrate (41) in the COF packaging structure (4) is covered with a protective adhesive layer (7) which wraps the edge of the driver chip (42) and the junction of the driver chip (42) and the flexible thin film substrate (41).

7. The ultra-thin liquid crystal module based on COF packaging technology according to claim 1, characterized in that, The bonding area of ​​the liquid crystal display panel (1) is bonded to the first end of the flexible thin film substrate (41) by anisotropic conductive adhesive. The projection of the integrated cavity (5) on the horizontal plane covers the projection of the driving chip (42) on the horizontal plane, and the opening area of ​​the integrated cavity (5) is larger than the bottom area of ​​the driving chip (42).

8. A method for manufacturing an ultra-thin liquid crystal module based on COF packaging technology, used to manufacture the ultra-thin liquid crystal module according to any one of claims 1 to 7, characterized in that, Includes the following steps: Step S1: Provide a liquid crystal display panel (1), a backlight module (2) and a mid-frame (3), wherein at least one integrated cavity (5) is pre-processed on the side surface of the backlight module (2) facing the liquid crystal display panel (1), and the integrated cavity (5) penetrates the reflective sheet (21) and extends into the interior of the light guide plate (22); Step S2: Bond the bonding area of ​​the liquid crystal display panel (1) to the first end of the flexible thin film substrate (41) in the COF packaging structure (4); Step S3: Apply or inject liquid photocurable viscoelastic material with a refractive index difference of ±0.02 between itself and the light guide plate (22) into the integrated cavity (5); then bend the second end of the flexible thin film substrate (41) in the COF packaging structure (4) toward the back side of the liquid crystal display panel (1) so that the driving chip (42) is aligned and gradually approaches the integrated cavity (5); then completely place the driving chip (42) into the photocurable viscoelastic material in the integrated cavity (5) so that the driving chip (42) is wetted by the photocurable viscoelastic material. The insertion process of the driving chip (42) is carried out at a slow speed of 0.1-1 mm / s until the bottom surface of the driving chip (42) contacts the bottom surface of the integrated cavity (5) or the buffer layer (6). After contact, a pressure of 0.05-0.2 MPa, which does not exceed the limit of the driving chip (42), is applied and maintained until the photocurable viscoelastic material is cured. Finally, after the photocurable viscoelastic material is cured, the driving chip (42) is embedded and fixed in the formed optical matching filler (8) to form a gapless optical coupling. Step S4: Connect the second end of the COF package structure (4) to the external circuit board; Step S5: Assemble and fix the liquid crystal display panel (1) with the backlight module (2) and the middle frame (3) so that the driving chip (42) is housed in the integrated cavity (5).

9. A method for manufacturing an ultra-thin liquid crystal module based on COF packaging technology according to claim 8, characterized in that, In step S1, the integrated cavity (5) is processed by laser engraving, CNC milling or mold integral forming. In step S3, before placing the driver chip (42) into the integrated cavity (5), a buffer layer (6) is first coated or attached to the bottom of the integrated cavity (5).

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