Method for back folding FOB of medium-and-large-size liquid crystal display module

Abstract

The invention provides a back folding FOB method for a medium-and-large-size liquid crystal display module. The back folding FOB method for the medium and large size liquid crystal display module comprises the steps that S1, an ADC12 aluminum alloy material is selected for preparing a BL die casting, deburring, I type anodic oxidation and surface flatness correction treatment are conducted on the BL die casting after preparation is completed, and a middle supporting column and a corner supporting column are arranged on the back face of the BL die casting; s2, sequentially stacking an LCD panel, a polaroid, a laminating film, an FPC (Flexible Printed Circuit) board and a PCB (Printed Circuit Board) to form an LCD module; and S3, coating the front and back surfaces of the PCB with self-repairing conductive adhesive layers. According to the method for back folding the FOB of the large-size liquid crystal display module, the thickness controllability and the structure protection performance of the module are improved, and the long-term stability and reliability of the module are enhanced.

Description

Technical Field

[0001] The present invention relates to the field of liquid crystal display technology, and in particular to a method for back-folding a FOB of a medium- or large-sized liquid crystal display module. Background Art

[0002] In existing designs for medium- and large-sized LCD modules, driver ICs or printed circuit boards (PCBs) are typically connected to panel flexible connectors using front-mounted or side-folding methods. These processes achieve signal and power transmission by laminating or folding the FPC at the edge of the display panel, while balancing ease of assembly and adaptability for mass production. To meet the demand for large-scale, high-resolution displays in industrial and commercial display screens and automotive central control systems, the size and routing density of panels and flexible connectors are continuously increasing, and the connection structure is gradually evolving towards higher integration and thinner thicknesses.

[0003] However, as panel size continues to increase, the existing side-folding structure has also exposed obvious shortcomings in thickness control, reliability and cost: the superposition of multiple layers of rigid support or metal structures makes it difficult to further compress the overall thickness of the module, and the local thickness is uneven, which is not conducive to lightweight design; the driving PCB and components are directly exposed to the back of the panel, lacking effective protection, and are easily damaged by collision during transportation or assembly. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a method for back-folding FOB of medium and large-sized liquid crystal display modules, which solves the problems of insufficient thickness controllability and insufficient protection of back components.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for back-folding FOB of medium and large-sized liquid crystal display modules, comprising:

[0006] S1. BL die-castings are prepared using ADC12 aluminum alloy. After preparation, the BL die-castings are deburred, anodized and surface flatness corrected using type Ⅰ treatment. The back of the BL die-casting is provided with intermediate support columns and corner support columns.

[0007] S2. The LCD panel, polarizer, laminating film, FPC board and PCB board are stacked in sequence to form an LCD module, and the end of the FPC board is connected to the PCB board pad by ultrasonic welding;

[0008] S3. A self-healing conductive adhesive layer is coated on both sides of the PCB board, wherein the self-healing conductive adhesive layer comprises smart microcapsules loaded with silver nanoparticles;

[0009] S4. The LCD module is attached to the back of the BL die-casting by a heating current. The bonding process is detected and adjusted by a micro piezoelectric sensor to ensure uniform and stable bonding between the module and the die-casting.

[0010] S5. Conduct environmental reliability test and electrical performance test.

[0011] Preferably, the number of the intermediate support columns is six, and the number of the corner support columns is four.

[0012] Preferably, the column depth of the middle support column is 3.0 mm, and the column depth of the corner support column is 7.45 mm. A predetermined space gap is formed between the middle support column, the corner support column and the liquid crystal display module to provide spatial protection for the liquid crystal display module to prevent external impact and extrusion.

[0013] Preferably, the thickness of the Type I anodized oxide film is not less than 10 μm, and the surface flatness correction processing error is less than 0.05 mm.

[0014] Preferably, the microcapsules rupture and release the silver nano-paste to perform self-repair, and the thickness of the microcapsule gel layer is 20 μm±5 μm.

[0015] Preferably, the silver nano-slurry has an average particle size of 48 nm to 52 nm, a resistivity of ≤1×10-5 Ω·cm, and a self-repair response time of ≤5 min.

[0016] Preferably, the micro piezoelectric sensor is arranged inside the supporting column, and the micro piezoelectric sensor monitors the fitting force between the LCD module and the BL die-casting in real time.

[0017] Preferably, the micro piezoelectric sensor adjusts the heating current through PID closed-loop control to ensure that the bonding force is 0.8N±0.05N. The PID closed-loop control model formula is as follows:

[0018]

[0019] e(t)=F ref -F(t),

[0020] Among them F ref =0.8N, F(t) is the bonding force measured by the sensor in real time, I(t) is the heating current, K p is the proportional gain coefficient, K i Integral gain coefficient, K d The micro piezoelectric sensor accurately monitors the fit between the module and the die casting, provides real-time feedback, and adjusts the heating current.

[0021] Real-time control ensures uniform distribution of the bonding force between the LCD module and the BL die-casting, preventing uneven pressure from causing localized areas of excessive thickness, such as thinness or thickness. This uniform bonding force ensures a stable overall module thickness, reducing errors during the production process. By effectively controlling and ensuring the stability of the bonding force, mechanical deformation and poor contact caused by uneven pressure can be reduced. This not only improves the controllability of the module's thickness but also enhances its long-term stability and reliability, avoiding functional issues caused by uneven thickness or module unevenness.

[0022] Preferably, the environmental reliability test includes a temperature cycle test, a damp heat test and a vibration test, and the electrical performance test includes a ground resistance test and a signal integrity test, to ensure that the module can operate reliably in extreme environments.

[0023] The present invention provides a method for back-folding FOB of medium- and large-sized liquid crystal display modules. It has the following beneficial effects:

[0024] This back-folding FOB method for large-scale LCD modules utilizes high-performance ADC12 aluminum alloy and precision-machined BL die-castings, significantly improving the module's thickness controllability and back-component protection. The design of the center and corner support columns not only ensures the stability of the LCD module but also effectively provides physical protection against damage caused by external impact or extrusion. Through the rational layout of the support columns, the module's thickness can be precisely controlled, resolving the uncontrollable thickness issue in existing technologies while also enhancing back-component protection.

[0025] The present invention further improves the long-term reliability of the module through the use of an innovative self-healing conductive adhesive layer and a micro piezoelectric sensor. The self-healing conductive adhesive layer can quickly repair electrical contact points when the microcapsule ruptures, avoiding common poor contact problems and improving the stability of electrical performance. The micro piezoelectric sensor monitors the bonding force in real time and adjusts the heating current through PID closed-loop control to ensure uniform and stable bonding between the LCD module and the die-casting. This innovative design ensures the module's reliability in harsh environments while maintaining its electrical performance and mechanical strength, greatly improving the module's adaptability in high-demand industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of a process for realizing the invention;

[0027] Figure 2 It is a structural diagram for realizing the invention.

[0028] Among them, 1. Middle support column; 2. Corner support column. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] Example 1

[0031] like Figure 1 As shown, an embodiment of the present invention provides a method for back-folding FOB of medium and large-sized liquid crystal display modules, including: S1. Selecting ADC12 aluminum alloy material to prepare BL die-castings, after the preparation, the BL die-castings are deburred, I-type anodized and surface flatness corrected, and an intermediate support column 1 and a corner support column 2 are provided on the back of the BL die-casting.

[0032] There are six center support columns (1) and four corner support columns (2). The center support columns (1) have a depth of 3.0mm, while the corner support columns (2) have a depth of 7.45mm. A predetermined gap is created between the center and corner support columns (1 and 2) and the LCD module to provide spatial protection from external impact and compression. The Type I anodized film must be no less than 10μm thick, and the surface flatness correction error must be less than 0.05mm.

[0033] S2. Stack the LCD panel, polarizer, laminating film, FPC board, and PCB board in sequence to form an LCD module. Connect the end of the FPC board to the PCB board pad through ultrasonic welding.

[0034] The specific implementation is as follows:

[0035] 1. LCD panel preparation

[0036] Select a 15" high-resolution LCD panel. Clean its surface to remove any dust and impurities that may affect the bonding performance.

[0037] 2. Polarizer lamination

[0038] Attach the polarizer to the surface of the LCD panel. Use a 1000g / cm 2 Highly transparent polarizer material with strong adhesion. The polarizer lamination process is carried out by a precision automatic laminating machine to ensure its precise and uniform position without bubbles or creases.

[0039] 3. Lamination film coating

[0040] Apply laminating film to the surface of the polarizer. This is done using a precision coating machine to ensure a uniform, bubble-free film layer. The laminating film further strengthens the LCD panel and protects it from external physical impact.

[0041] 4. FPC board stacking

[0042] Overlay the flexible printed circuit board (FPC) with the laminating film. Connect the ends of the FPC to the PCB pads using ultrasonic welding. The FPC's length is adjusted to meet specific requirements, and its width is 10 mm. The pads on the FPC mate with corresponding pads on the PCB.

[0043] 5. Ultrasonic welding

[0044] Ultrasonic welding equipment was used for welding, and the following parameters were used:

[0045] Welding frequency: 40kHz.

[0046] Welding power: 100W.

[0047] Welding time: 0.5 seconds.

[0048] Welding pressure: 50N.

[0049] Through ultrasonic welding, the FPC board and the pads of the PCB board form a firm electrical connection, ensuring stable signal transmission.

[0050] 6. Visual and electrical inspection

[0051] After ultrasonic welding, a visual inspection is performed to ensure that the solder joints are flawless. An automated optical inspection system is used to check the connection quality of the soldered areas to ensure there are no cold joints, false solder joints, or other electrical contact issues. Electrical functional testing is also performed to confirm that signal transmission between the FPC and PCB is correct.

[0052] 7. Assembly completed

[0053] Finally, all components are fixed to the support structure of the BL die casting to complete the assembly of the LCD module.

[0054] This specific embodiment describes in detail the parameters and operations of each step to ensure efficient assembly of the LCD module and guarantee its electrical performance and mechanical strength.

[0055] S3. Apply a self-healing conductive adhesive layer on both sides of the PCB. The self-healing conductive adhesive layer contains smart microcapsules loaded with silver nanoparticles. The microcapsules rupture and release the silver nanoparticles for self-healing. The thickness of the microcapsule adhesive layer is 20μm±5μm. The average particle size of the silver nanoparticles is 48nm-52nm and the resistivity is ≤1×10 -5Ω·cm, self-repair response time ≤5min.

[0056] The specific implementation is as follows:

[0057] Environmental conditions: Standard environmental conditions.

[0058] 1. PCB board surface preparation

[0059] PCBs undergo a multi-step cleaning process. The surface is thoroughly rinsed with deionized water to remove all dust and impurities. Isopropyl alcohol is then used to clean the surface to remove oil, fingerprints, and other residue. The cleaned PCBs are then dried in a 40°C oven for 30 minutes to ensure a completely clean surface free of residual moisture.

[0060] 2. Apply self-repairing conductive adhesive layer

[0061] A precision coating machine is used to evenly coat the self-healing conductive adhesive layer on both sides of the PCB. The conductive adhesive formula includes:

[0062] Smart microcapsule: The diameter of the microcapsule is 10μm±2μm, and it is filled with silver nano-paste. The microcapsule is designed to be temperature-sensitive and can break when subjected to external force, releasing nano-silver paste for self-repair.

[0063] Silver nano-paste: The average particle size of silver nano-paste is 50nm, and the resistivity is ≤1×10 -5 Ω·cm, the high conductivity of the slurry makes the electrical contact after self-healing more stable and has low resistance.

[0064] Adhesive layer thickness: The thickness of the conductive adhesive layer is 20μm±5μm, and automated coating equipment is used to ensure the uniformity and consistency of the coating.

[0065] 3. Self-repair performance test

[0066] Self-healing performance testing was conducted under standard conditions, at 25°C and 60% humidity. A precision instrument was used to gently indent the conductive adhesive layer, locally destroying the microcapsules and releasing the silver nanoparticles to repair them. After five minutes, a multimeter was used to measure resistance recovery. The results showed that the resistance had recovered to 98% of its original value. This result demonstrates the excellent self-healing capabilities of the self-healing conductive adhesive layer under standard conditions, effectively repairing the electrical connection after microcapsule rupture and ensuring long-term stability.

[0067] 4. Further verification

[0068] To further verify the durability of the conductive adhesive layer, PCBs coated with the self-healing conductive adhesive were subjected to 1000 open-close cycles, with each cycle applying slight stress to the adhesive layer. The results showed that after prolonged physical stress, the conductive adhesive layer's resistance changed by less than 5% and quickly recovered to its original resistance, demonstrating that the adhesive layer remains stable under mechanical stress.

[0069] S4. The LCD module is bonded to the back of the BL die-casting using a heating current. During the bonding process, a micro-piezoelectric sensor detects and adjusts the heating current to ensure uniform and stable bonding between the module and the die-casting. The micro-piezoelectric sensor, located inside the support column, monitors the bonding force between the LCD module and the BL die-casting in real time.

[0070] The micro piezoelectric sensor adjusts the heating current through PID closed-loop control to ensure the bonding force is 0.8N±0.05N. The PID closed-loop control model formula is as follows:

[0071]

[0072] e(t)=F ref -F(t),

[0073] Among them F ref =0.8N, F(t) is the bonding force measured by the sensor in real time, I(t) is the heating current, K p is the proportional gain coefficient, K i Integral gain coefficient, K d is the differential gain coefficient.

[0074] Real-time control ensures uniform distribution of the bonding force between the LCD module and the BL die-casting, preventing uneven pressure from causing localized areas of excessive thickness (thin or thick). This uniform bonding force ensures a stable overall module thickness, reducing errors during the production process. By effectively controlling and ensuring the bonding force's stability, mechanical deformation and poor contact caused by uneven pressure can be reduced. This not only improves the module's thickness controllability and structural protection, but also enhances its long-term stability and reliability, avoiding functional issues caused by uneven thickness or module flatness.

[0075] The specific implementation is as follows:

[0076] Environmental conditions: Standard environmental conditions.

[0077] 1. Initial Setup

[0078] At a normal ambient temperature of 25°C and 60% humidity, the contact surfaces between the LCD module and the BL die-casting are first pre-treated. Automated equipment ensures precise stacking of the LCD panel, polarizer, and FPC board, ensuring there are no bubbles between the layers and precise positioning. Subsequently, a hot press heats the back of the BL die-casting, while simultaneously energizing the heating current to initiate the bonding process.

[0079] 2.PID control settings

[0080] Miniature piezoelectric sensors are placed inside the support columns of the BL die-casting to monitor the bonding force between the LCD module and the BL die-casting in real time. Initial testing showed a bonding force of 0.65N. A lower bonding force indicates that the heating current needs to be adjusted to ensure it reaches the target value. The PID control system is activated and automatically makes feedback adjustments.

[0081] 3. Heating current adjustment

[0082] Based on real-time feedback, the PID control system adjusts the heating current to 0.8A, ensuring the bonding force remains within the range of 0.8N±0.05N. The control system adjusts the heating current based on the bonding force data fed back by the sensor to ensure that the bonding force remains evenly distributed throughout the bonding process. This helps prevent unstable thickness due to excessive pressure in localized areas or poor contact due to insufficient pressure.

[0083] 4. Implementation Effect

[0084] After approximately three minutes of lamination, the PID control system ensures a stable lamination force within the range of 0.8N ± 0.05N. At this point, the bonding force between the LCD module and the BL die-casting is uniform and stable, and the overall thickness of the module is precisely controlled, ensuring high product quality and consistency. Thanks to precise control of the heating current, the final module thickness error is less than 0.05mm, meeting design requirements.

[0085] S5. Conduct environmental reliability testing and electrical performance testing. Environmental reliability testing includes temperature cycling testing, humidity testing, and vibration testing. Electrical performance testing includes ground resistance testing and signal integrity testing to ensure the module operates reliably in extreme environments.

[0086] Example 2

[0087] The difference between this embodiment and the first embodiment is that the environmental condition of this embodiment is a high temperature environment.

[0088] 1. Self-repairing conductive adhesive layer

[0089] 1.1PCB board surface preparation

[0090] PCBs undergo a multi-step cleaning process. The surface is thoroughly rinsed with deionized water to remove all dust and impurities. Isopropyl alcohol is then used to clean the surface to remove oil, fingerprints, and other residue. The cleaned PCBs are then dried in a 40°C oven for 30 minutes to ensure a completely clean surface free of residual moisture.

[0091] 1.2 Coating self-repairing conductive adhesive layer

[0092] The self-healing conductive adhesive layer was applied using the same formula as in Example 1. After coating, the PCB was placed in an oven at 100°C for heat curing. The curing time was 10 minutes, ensuring that the conductive adhesive layer was fully cured and maintained stable performance even in high-temperature environments.

[0093] 1.3 Self-repair performance test

[0094] A PCB coated with a self-healing conductive adhesive layer was placed in a high-temperature environment and tested in an oven at 100°C. A force of 1N was applied to partially destroy the microcapsules. After 5 minutes, a multimeter was used to measure the resistance recovery. The results showed that after 5 minutes, the resistance had recovered to 96% of its original value. This result demonstrates that the conductive adhesive layer can effectively self-heal and restore electrical performance even in high-temperature environments.

[0095] 1.4 High temperature cycle verification

[0096] To verify long-term stability in high-temperature environments, PCBs coated with the conductive adhesive were subjected to continuous operation at 100°C for 500 hours, simulating long-term high-temperature use. Test results show that even under long-term high-temperature exposure, the conductive adhesive layer maintains its electrical properties, with a resistance change of only 3%, demonstrating excellent high-temperature resistance and stability.

[0097] 2. Micro piezoelectric sensor

[0098] 2.1 Initial Setup

[0099] The LCD module and BL die-casting are preheated by a heating current at a high temperature of 80°C. Since high temperature causes material expansion, a higher heating current is usually required to ensure close contact between the LCD module and the BL die-casting.

[0100] 2.2PID control settings

[0101] The micro piezoelectric sensor continued to monitor the bonding force between the LCD module and the BL die-casting. During the test, the real-time measured bonding force was 0.75N, below the target value (0.8N). The PID control system compensated by adjusting the heating current based on the sensor feedback data.

[0102] 2.3 Heating current adjustment

[0103] The PID control system uses real-time feedback to adjust the heating current to 1.0A. As the heating current increases, the bonding force between the LCD module and the BL die-casting gradually increases, ultimately stabilizing within a range of 0.8N±0.05N. Because high temperatures can cause material expansion, precise monitoring by micro-piezoelectric sensors ensures uniform bonding force, avoiding localized deformation caused by excessive pressure.

[0104] 2.4 Implementation Effect

[0105] Under high-temperature conditions, the PID control system is able to maintain uniform bonding force, ensuring uniform contact between the LCD module and the BL die-casting. The module thickness is stable within the range of 0.8N±0.05N, and the thickness error of the final product is 0.04mm, meeting the design specifications and ensuring the long-term stability and reliability of the module.

[0106] Example 3

[0107] The difference between this embodiment and the first embodiment is that the environmental condition of this embodiment is a low temperature environment.

[0108] 1. Self-repairing conductive adhesive layer

[0109] 1.1PCB board surface preparation

[0110] PCBs undergo a multi-step cleaning process. The surface is thoroughly rinsed with deionized water to remove all dust and impurities. Isopropyl alcohol is then used to clean the surface to remove oil, fingerprints, and other residue. The cleaned PCBs are then dried in a 40°C oven for 30 minutes to ensure a completely clean surface free of residual moisture.

[0111] 1.2 Coating self-repairing conductive adhesive layer

[0112] The same formulation as in Example 1 was used for coating, and the coated PCB board was placed in a low-temperature environment of -20°C for curing. The curing time was set to 15 minutes to ensure that the conductive adhesive layer could be fully cured even at low temperatures.

[0113] 1.3 Self-repair performance test

[0114] Self-healing performance was tested in a low-temperature environment. A PCB coated with the self-healing conductive adhesive layer was placed at -20°C, and a micro-needle was used to lightly scratch the surface, destroying the microcapsules. After 5 minutes, a multimeter was used to measure the resistance recovery. The test results showed that the resistance had recovered to 92% of its original value. Although the self-healing efficiency was slightly reduced in the low-temperature environment, the conductive adhesive layer was still able to effectively restore electrical performance and maintain a relatively stable resistance.

[0115] 1.4 Long-term performance under low temperature test

[0116] The PCB board coated with the conductive adhesive layer was then placed in a -20°C environment for 1000 hours to simulate long-term low-temperature use. The results showed that the self-healing conductive adhesive layer maintained a low resistance change at low temperatures, demonstrating its reliability in extreme low-temperature environments.

[0117] 2. Micro piezoelectric sensor

[0118] 2.1 Initial Setup

[0119] In a low temperature environment (-10°C), the initial heating current of the LCD module and BL die casting is set higher to avoid hardening of the material and poor surface contact caused by the low temperature environment. The initial heating current is set to 1.2A.

[0120] 2.2PID control settings

[0121] The micro piezoelectric sensor continues to monitor the bonding force between the LCD module and the BL die-casting, detecting a real-time bonding force of 0.7 N. The PID control system activates, adjusting the heating current in real time based on sensor feedback to ensure the bonding force remains within the target range.

[0122] 2.3 Heating current adjustment

[0123] The PID control system adjusts the heating current from 1.2A to 0.95A based on real-time data feedback. As the heating current gradually decreases, the bonding force ultimately stabilizes within a range of 0.8N ± 0.05N. In low-temperature environments, PID closed-loop control prevents material hardening and poor contact caused by low temperatures, thereby ensuring stable module thickness.

[0124] 2.4 Implementation Effect

[0125] Even in low-temperature environments, the PID control system ensures a stable bonding force between the LCD module and the BL die-casting within a range of 0.8N±0.05N by regulating the heating current. The low temperature environment does not negatively impact the thickness stability of the module, ensuring uniform thickness and ensuring product quality.

[0126] Example 4

[0127] The difference between this embodiment and the first embodiment is that the environmental condition of this embodiment is a high humidity environment.

[0128] 1. Self-repairing conductive adhesive layer

[0129] 1.1PCB board surface preparation

[0130] PCBs undergo a multi-step cleaning process. The surface is thoroughly rinsed with deionized water to remove all dust and impurities. Isopropyl alcohol is then used to clean the surface to remove oil, fingerprints, and other residue. The cleaned PCBs are then dried in a 40°C oven for 30 minutes to ensure a completely clean surface free of residual moisture.

[0131] 1.2 Coating self-repairing conductive adhesive layer

[0132] The self-healing conductive adhesive layer was evenly coated on both sides of the PCB using the same coating process as in Example 1. After coating, the PCB was placed in an environment with a relative humidity of 95% for curing for 10 minutes.

[0133] 1.3 Self-repair performance test

[0134] Self-healing performance was tested in a high-humidity environment. A pressure of 2N was applied to the microcapsules, and after 5 minutes, resistance recovery was measured. The results showed that the resistance had recovered to 99% of its original value. This demonstrates that the conductive adhesive layer not only maintains excellent self-healing capabilities in high-humidity environments, but can also effectively repair resistance changes caused by microcapsule rupture due to external forces.

[0135] S1.4 Long-term stability test in high humidity environment

[0136] To further verify its stability in high-humidity environments, PCBs coated with the self-healing conductive adhesive were subjected to operation at 95% humidity and 40°C for 1000 hours. The test results showed that after prolonged high-humidity exposure, the conductive adhesive layer's resistance changed by less than 5%, demonstrating excellent moisture resistance and long-term stability.

[0137] 2. Micro piezoelectric sensor

[0138] 2.1 Initial Setup

[0139] In a high humidity environment (90% humidity), the heating current of the LCD module and the BL die casting is initially set to 1.05A to compensate for the effect of moisture on the adhesion of the glue layer.

[0140] 2.2PID control settings

[0141] The micro piezoelectric sensor continues to monitor the bonding force between the LCD module and the BL die-casting. Real-time feedback indicates a bonding force of 0.75N. The PID control system adjusts the heating current based on this data to ensure that the bonding force remains within the target range.

[0142] 2.3 Heating current adjustment:

[0143] The PID control system gradually adjusts the heating current to 1.1 A, stabilizing the bonding force at 0.8 N ± 0.05 N. By adjusting the heating current in real time, the system ensures uniform contact force between the adhesive layer and the substrate in high-humidity environments, preventing moisture from affecting bonding quality.

[0144] 2.4 Implementation Effect

[0145] In a high-humidity environment, PID closed-loop control maintains a stable bonding force between the LCD module and the BL die-casting within 0.8N±0.05N. The impact of moisture on the adhesive layer is effectively controlled, resulting in a stable module thickness and guaranteed product quality.

[0146] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for back-folding FOB of medium and large-sized liquid crystal display modules, characterized in that: include: S1. BL die castings are prepared from ADC12 aluminum alloy material. After preparation, the BL die castings are subjected to deburring, type Ⅰ anodizing, and surface flatness correction. The back of the BL die casting is provided with an intermediate support column (1) and a corner support column (2); S2. The LCD panel, polarizer, laminating film, FPC board and PCB board are stacked in sequence to form an LCD module, and the end of the FPC board is connected to the PCB board pad by ultrasonic welding; S3. A self-healing conductive adhesive layer is coated on both sides of the PCB board, wherein the self-healing conductive adhesive layer comprises smart microcapsules loaded with silver nanoparticles; S4. The LCD module is attached to the back of the BL die-casting by a heating current. The attachment process is detected by a micro piezoelectric sensor and the heating current is adjusted; S5. Conduct environmental reliability test and electrical performance test.

2. The method for back-folding a FOB of a medium-to-large-sized liquid crystal display module according to claim 1, characterized in that: The number of the intermediate support columns (1) is six, and the number of the corner support columns (2) is four.

3. The method for back-folding a FOB of a medium-to-large-sized liquid crystal display module according to claim 1, characterized in that: The column depth of the middle support column (1) is 3.0 mm, the column depth of the corner support column (2) is 7.45 mm, and a predetermined space gap is formed between the middle support column (1), the corner support column (2) and the liquid crystal display module.

4. The method for back-folding a FOB of a medium-to-large-sized liquid crystal display module according to claim 3, characterized in that: The thickness of the Type I anodized oxide film is not less than 10 μm, and the surface flatness correction processing error is less than 0.05 mm.

5. The method for back-folding a FOB of a medium-to-large-sized liquid crystal display module according to claim 1, characterized in that: The microcapsule ruptures and releases the silver nano-paste to perform self-repair, and the thickness of the microcapsule glue layer is 20 μm±5 μm.

6. The method for back-folding a FOB of a medium-to-large-sized liquid crystal display module according to claim 1, characterized in that: The silver nano-paste has an average particle size of 48 nm to 52 nm, a resistivity of ≤1×10-5 Ω·cm, and a self-repair response time of ≤5 min.

7. The method for back-folding a FOB of a medium-to-large-sized liquid crystal display module according to claim 1, characterized in that: The micro piezoelectric sensor is arranged inside the supporting column, and the micro piezoelectric sensor monitors the bonding force between the LCD module and the BL die-casting in real time.

8. The method for back-folding a FOB of a medium-to-large-sized liquid crystal display module according to claim 1, characterized in that: The micro piezoelectric sensor adjusts the heating current through PID closed-loop control to ensure that the bonding force is 0.8N±0.05N. The PID closed-loop control model formula is as follows: e(t)=F ref -F(t), Among them F ref =0.8N, F(t) is the bonding force measured by the sensor in real time, I(t) is the heating current, K p is the proportional gain coefficient, K i Integral gain coefficient, K d is the differential gain coefficient.

9. The method for back-folding a FOB of a medium-to-large-sized liquid crystal display module according to claim 1, characterized in that: The environmental reliability test includes a temperature cycle test, a damp heat test, and a vibration test, and the electrical performance test includes a ground resistance test and a signal integrity test.

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