A COB display module repairing method based on thermal lamination packaging technology

Abstract

The application discloses a COB display module repairing method based on a thermal lamination packaging technology, and relates to the technical field of semiconductor display packaging, and comprises the following steps: preparing a repairing film, wherein the repairing film is a thermosetting adhesive film; performing cleaning treatment on a defect area of a COB display module, so as to remove surface contaminants; peeling off a protective film on the repairing film at room temperature, and attaching a bare repairing film to a surface of the defect area; placing the COB display module with the repairing film in a vacuum heat pressing device, and performing thermal lamination repairing under the conditions of heating, pressurizing and vacuumizing, so that the repairing film material fills the defect area; and performing peeling and solidifying treatment after cooling, so that the repairing film and an original packaging layer form an integrated structure, and the problem that packaging defects are difficult to repair in the prior art can be solved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor display packaging technology, and in particular to a method for repairing COB display modules based on thermal lamination packaging technology. Background Technology

[0002] COB (Chip on Board) display modules are a display technology that involves directly bonding multiple LED chips onto a PCB substrate and then encapsulating the entire module with encapsulating adhesive. Compared to traditional SMD (Surface Mount Device) solutions, COB display modules offer higher reliability, smaller pixel pitch, and better display uniformity, and are currently widely used in indoor high-definition displays, commercial displays, and high-end conference all-in-one machines.

[0003] In the manufacturing process of COB display modules, thermal lamination encapsulation technology is widely used in the encapsulation of Mini LED and MicroLED / COB display modules. This technology involves using heat, pressure, and vacuum to melt and flow thermosetting adhesive film materials, filling the gap between the chip and the substrate, and forming an integrated, dense protective layer after cooling. The key to this technology is "one-step molding," meaning there are no physical interface gaps between the encapsulation layer, the substrate, and the chip. To achieve high black uniformity and light extraction efficiency in display modules, multi-layer composite structures are often used, such as a sandwich structure of "transparent layer—black layer—transparent layer," where the black layer is precisely sandwiched between two transparent layers, ensuring both appearance and avoiding interference with light extraction. Thermal lamination encapsulation offers advantages such as high hermeticity, high surface flatness, and suitability for thin-film and fine-pitch encapsulation.

[0004] However, thermal lamination is an irreversible process. Once formed, traditional local repair methods (such as dispensing fillers or cutting and resealing) can easily damage the original structure, leading to appearance defects, poor interface bonding, or reduced airtightness. Since COB display modules involve multiple processes during production, including die bonding, semi-permeable lamination, thermal lamination curing, appearance inspection, and lighting tests, any abnormality in any stage can damage the module's appearance. Common appearance defects include: scratches and abrasions on the encapsulation surface, filler areas exceeding customer-acceptable standards, pits, bumps, bubbles, and impacts. These defects not only affect the product's appearance quality but may also compromise the integrity of the encapsulation structure, reduce airtightness, and consequently affect display performance and long-term reliability.

[0005] Therefore, there is a need to provide a repair method that enables reversible repair and effectively improves the airtightness after repair without damaging the original packaging structure or causing any appearance defects. Summary of the Invention

[0006] This invention provides a method for repairing COB display modules based on thermal lamination packaging technology, which can solve the problem of difficult repair of packaging defects in the prior art.

[0007] To address the above problems, this invention provides a COB display module repair method based on thermal lamination encapsulation technology, comprising the following steps: Prepare a repair film, wherein the repair film is a thermosetting adhesive film; The defective areas of the COB display module are cleaned to remove surface contaminants. Peel off the second protective film on the repair film and temporarily attach the exposed adhesive surface of the repair film to the surface of the defect area; The COB display module with the repair film is placed in a vacuum hot press equipment and hot lamination repair is performed under heating, pressurization and vacuum conditions. After cooling, a peeling process is performed and a curing process is carried out to form an integrated structure between the repair film and the original encapsulation layer.

[0008] The present invention provides a COB display module repair method based on thermal lamination encapsulation technology, which has the following beneficial effects compared with the prior art: By preparing a thermosetting adhesive film as a repair film, the defective area is directly applied to the surface after cleaning. Vacuum hot pressing is used to melt and flow the repair film material, fully filling the defective area. After cooling, peeling, and curing, an integrated structure is formed, thus achieving reversible repair without damaging the original encapsulation layer. After repair, there are no interface marks, no color difference, no bubbles, and good appearance consistency. At the same time, because the repair film and the original encapsulation layer are fused at the molecular level, the airtightness is restored to the original standard or even better. This effectively avoids the secondary damage and scrap risk caused by traditional cutting or glue application repair, significantly reducing production costs and improving product yield.

[0009] Preferably, the method for preparing the repair membrane includes: An anti-glare material layer is prepared by coating the first protective film with an anti-glare material using a precision coating device, followed by baking and cooling to form the anti-glare material layer. A thermosetting layer is prepared by applying a thermosetting material onto the anti-glare material layer using a precision coating device, followed by baking and cooling to form the thermosetting layer. The anti-glare material layer and the thermosetting layer are combined by heating and pressing with a composite roller to form a multi-layer composite repair film, and then a second protective film is covered on the surface of the thermosetting layer.

[0010] Preferably, the thermosetting layer is a silicone-modified epoxy resin layer with a thickness of 10-17 μm.

[0011] Preferably, the anti-glare material layer is an AG layer with a thickness of 10-20 μm.

[0012] Preferably, in the hot lamination repair step, the heating temperature is 80-120℃, the pressure is 0.1-1.0MPa, the vacuum degree is less than 100Pa, and the holding time is 5-20 minutes.

[0013] Preferably, the defective area of ​​the COB display module is a localized damaged area on the packaging surface, including one or more of the following: mechanical scratches, abrasions, pits, bubbles, bumps, or the area of ​​adhesive repair exceeding the standard range.

[0014] Preferably, the cleaning process involves wiping with a lint-free cloth and anhydrous ethanol or plasma cleaning.

[0015] Preferably, the total thickness of the repair membrane is 20-37 μm.

[0016] Preferably, the curing temperature in the curing process is 130-160℃, and the curing time is 30-90 minutes.

[0017] Preferably, the peeling operation is to peel off the first protective film on the surface of the repair film after cooling. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the overall process of the COB display module repair method based on thermal lamination packaging technology according to an embodiment of the present invention; Figure 2 This is a schematic flowchart of the method for preparing the repair membrane according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the repair membrane structure according to an embodiment of the present invention. Figure 1 ; Figure 4 This is a schematic diagram of the repair membrane structure according to an embodiment of the present invention. Figure 2 .

[0020] Explanation of reference numerals in the attached figures: 100. First protective film; 200. Second protective film; 300. Anti-glare material layer; 400. Thermosetting layer. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this application clearer, specific embodiments of this application are described clearly and completely below with reference to the accompanying drawings. It should be understood that the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments described in this application without creative effort will fall within the scope of protection of this application.

[0022] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in the specification of this application is for the purpose of describing specific embodiments only and is not intended to limit this application; the terms "comprising," "including," "having," "containing," "comprise," etc., in the specification, claims, and accompanying drawings of this application are open-ended terms, indicating that a method comprises one or more steps, or an apparatus comprises one or more elements, but not excluding the inclusion of other steps or elements. The terms "first," "second," etc., in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy. Furthermore, the terms "first" and "second" 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. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0023] In the description of this application, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application 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 application.

[0024] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "attachment" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0025] It should be emphasized that when the term "comprising / including" is used in this specification, it is used to explicitly indicate the presence of the stated feature, integer, step, or component, but does not exclude the presence or addition of one or more other features, integers, steps, parts, or groups of features, integers, steps, or parts.

[0026] like Figures 1 to 4 As shown in the figure, an embodiment of the present invention provides a COB display module repair method based on thermal lamination packaging technology, which includes the following steps: Prepare a repair film, wherein the repair film is a thermosetting adhesive film; The defective areas of the COB display module are cleaned to remove surface contaminants. Peel off the second protective film 200 on the repair film and temporarily attach the exposed repair film bonding surface to the surface of the defect area; The COB display module with the repair film is placed in a vacuum hot press equipment and hot lamination repair is performed under heating, pressurization and vacuum conditions. After cooling, a peeling process is performed and a curing process is carried out to form an integrated structure between the repair film and the original encapsulation layer.

[0027] By using thermosetting adhesive film as the repair film, it is integrated with the original encapsulation layer of the defective area under vacuum hot pressing conditions. The entire repair process does not require cutting or grinding the original encapsulation layer, achieving reversible repair and avoiding module scrapping. At the same time, there are no interface marks, color differences or bubbles after repair, maintaining the ink color consistency and appearance smoothness of the module surface. In addition, the repair film and the original encapsulation layer undergo molecular-level fusion and curing to form a dense protective layer, which significantly improves the airtightness of the repaired area and ensures the long-term reliability of the module.

[0028] In this embodiment, the preparation method of the repair film includes: preparing an anti-glare material layer 300, coating the anti-glare material onto the first protective film 100 using a precision coating device, and baking and cooling to form the anti-glare material layer 300; preparing a thermosetting layer 400, coating the anti-glare material layer 300 onto the anti-glare material layer 300 using a precision coating device, and baking and cooling to form the thermosetting layer 400; bonding the anti-glare material layer 300 and the thermosetting layer 400 together using a heated composite roller to form a multi-layer composite repair film, and then covering the surface of the thermosetting layer 400 with a second protective film 200.

[0029] Furthermore, the anti-glare material layer 300 uses a transparent modified resin, such as AG material, with a refractive index matching that of the thermosetting layer 400. At the same time, nano-silica particles are added to adjust the surface haze, so that it is consistent with the optical effect of the original encapsulation layer surface, avoiding the difference in reflection in the repaired area from affecting the display appearance.

[0030] In the actual repair process, the dummy application only requires gently applying the repair film to the defect area; it does not need to be pressed firmly to avoid introducing air bubbles prematurely. During vacuum hot pressing, the vacuum environment will pre-extract the air between the repair film and the defect area. Combined with heating and pressurization, this allows the molten repair film material to completely fill the uneven defect area, preventing air bubble residue. After cooling, the repair film has initially set. At this point, peeling off the first protective film 100 will not cause the repair film to shift. Then, placing it in an oven for overall curing will result in a stable, integrated repair structure.

[0031] In this embodiment, the thermosetting layer 400 is an organosilicon-modified epoxy resin layer with a thickness of 10-17 μm.

[0032] Silicone-modified epoxy resin combines the high bonding strength of epoxy resin with the flexibility and weather resistance of silicone, enabling it to form a molecular-level fusion with the original encapsulation layer of COB display modules, significantly improving the bonding strength and airtightness of the repair interface.

[0033] In this embodiment, the anti-glare material layer 300 is an AG layer with a thickness of 10-20 μm.

[0034] The AG layer can effectively reduce ambient light reflection on the surface of the display module. After repair, the layer is exposed on the module surface, ensuring the consistency of ink color and visual uniformity between the repaired area and the surrounding area, and avoiding the color difference problem common in traditional repair methods.

[0035] In this embodiment of the application, the heating temperature in the hot lamination repair step is 80-120℃, the pressure is 0.1-1.0MPa, the vacuum degree is less than 100Pa, and the holding time is 5-20 minutes.

[0036] In the above process, the COB display module with the dummy repair film attached is placed in a hot press with a vacuum chamber. The vacuum system is activated to achieve a vacuum level of 80 Pa within the chamber. Simultaneously, heating is applied to uniformly raise the temperature of the module and the repair film to 120°C. After the temperature stabilizes, a pressure of 0.5 MPa is applied to the upper pressure head and maintained for 10 minutes. Under these conditions, the repair film material completely melts, its viscosity decreases, and it flows fully under pressure, filling the tiny voids in the defect area. Due to the vacuum environment, air bubbles are effectively eliminated. After the holding period, heating is stopped, and the module is allowed to cool naturally to room temperature under pressure.

[0037] The determination of this parameter range is based on the melting characteristics of thermosetting modified silicone resins: below 80℃, the material's fluidity is insufficient, and above 120℃, the resin may cure prematurely, affecting the filling effect; therefore, the hot lamination temperature is controlled between 80-120℃ to ensure sufficient melting and flow of the material without cross-linking. The curing stage temperature needs to be higher than the hot lamination temperature, controlled between 130-160℃ to ensure sufficient cross-linking. If the temperature is too low or the time is too short, the cross-linking will be incomplete, and the repair layer may be too soft and have poor weather resistance; if the temperature is too high or the time is too long, it may cause the material to yellow or shrink.

[0038] In this embodiment of the application, the defective area is a localized damaged area on the packaging surface, including one or more of the following: mechanical scratches, abrasions, pits, bubbles, bumps, or the area of ​​adhesive repair exceeding the standard range.

[0039] If these defective areas are not addressed promptly, they will not only affect the appearance consistency and aesthetics of the COB display module, but may also become channels for external contaminants such as moisture and dust to penetrate, causing corrosion or damage to critical components such as internal LED chips and gold wires. This can lead to problems such as abnormal lighting, brightness decay, or even short-circuit failure, severely impacting the lifespan and reliability of the display module. Therefore, precise and effective repair of these defective areas is a crucial step in ensuring the production yield and product quality of COB display modules.

[0040] In this embodiment of the application, the cleaning process uses a lint-free cloth with anhydrous ethanol for wiping or plasma cleaning.

[0041] For cases with severe organic contamination, plasma cleaning can be used. This involves bombarding the surface with plasma to decompose organic molecules, increasing surface energy, which is beneficial for repairing false adhesion of the film and subsequent fusion. After cleaning, ensure that there are no residual contaminants on the surface, but avoid causing any mechanical damage to the original encapsulation layer.

[0042] In this embodiment, the total thickness of the repair membrane is 20-37 μm.

[0043] This thickness range covers the depth of most common defects. For minor scratches or abrasions, a thin repair film of 20-25 μm can be used; for deeper dents or impacts, a thicker repair film of 30-35 μm can be used. In actual production, repair films of different thicknesses can be prepared for use.

[0044] In this embodiment of the application, the curing temperature in the curing process is 130-160℃, and the curing time is 30-90 minutes.

[0045] In a preferred embodiment, the curing temperature is 140°C and the curing time is 60 minutes.

[0046] After curing, covalent bonds are formed between the repair film and the original encapsulation layer, the interface disappears, and the airtightness reaches or exceeds the original standard. If the curing temperature is too low or the time is too short, the cross-linking is incomplete, and the repair layer may be too soft and have poor weather resistance; if the temperature is too high or the time is too long, it may cause the material to yellow or shrink.

[0047] In this embodiment of the application, the peeling operation is to peel off the first protective film 100 on the surface of the repair film after cooling.

[0048] As described above, after the heat lamination repair is completed, the module is removed from the press and allowed to cool naturally to room temperature. At this point, the repair film material is in a semi-cured stage, and the first protective film 100 on the surface, i.e., the release film, can still be easily peeled off. The operator holds a corner of the release film with their hand or tweezers and peels it off from the surface of the repair film at a uniform speed.

[0049] After peeling, the repaired area has a smooth surface with no residual release film fragments, and can then proceed to the post-curing step. The above-disclosed embodiments are merely a few specific examples of the present invention; however, the embodiments of the present invention are not limited thereto, and any variations conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. A method for repairing a COB display module based on thermal lamination encapsulation technology, characterized in that, Includes the following steps: Prepare a repair film, wherein the repair film is a thermosetting adhesive film; The defective areas of the COB display module are cleaned to remove surface contaminants. Peel off the second protective film (200) on the repair film and temporarily attach the exposed repair film bonding surface to the surface of the defect area; The COB display module with the repair film is placed in a vacuum hot press equipment and hot lamination repair is performed under heating, pressurization and vacuum conditions. After cooling, a peeling process is performed and a curing process is carried out to form an integrated structure between the repair film and the original encapsulation layer.

2. The method for repairing a COB display module based on thermal lamination encapsulation technology according to claim 1, characterized in that, The method for preparing the repair membrane includes: An anti-glare material layer (300) is prepared by coating the anti-glare material onto the first protective film (100) using a precision coating equipment, and then baking and cooling to form the anti-glare material layer (300). A thermosetting layer (400) is prepared by applying a thermosetting material onto the anti-glare material layer (300) using a precision coating device, followed by baking and cooling to form the thermosetting layer (400). The anti-glare material layer (300) and the thermosetting layer (400) are combined by heating and pressing with a composite roller to form a multi-layer composite repair film, and then a second protective film (200) is covered on the surface of the thermosetting layer (400).

3. The method for repairing a COB display module based on thermal lamination encapsulation technology according to claim 2, characterized in that, The thermosetting layer (400) is an organosilicon-modified epoxy resin layer with a thickness of 10-17 μm.

4. A method for repairing a COB display module based on thermal lamination encapsulation technology according to claim 2, characterized in that, The anti-glare material layer (300) is an AG layer with a thickness of 10-20μm.

5. A method for repairing a COB display module based on thermal lamination encapsulation technology according to claim 1, characterized in that, In the hot lamination repair step, the heating temperature is 80-120℃, the pressure is 0.1-1.0MPa, the vacuum degree is less than 100Pa, and the holding time is 5-20 minutes.

6. A method for repairing a COB display module based on thermal lamination encapsulation technology according to claim 1, characterized in that, The defective area of ​​the COB display module is a localized damaged area on the packaging surface, including one or more of the following: mechanical scratches, abrasions, pits, bubbles, bumps, or the area of ​​adhesive repair exceeding the standard range.

7. A method for repairing a COB display module based on thermal lamination encapsulation technology according to claim 1, characterized in that, The cleaning process involves wiping with a lint-free cloth and anhydrous ethanol or plasma cleaning.

8. A method for repairing a COB display module based on thermal lamination encapsulation technology according to claim 1, characterized in that, The total thickness of the repair membrane is 20-37 μm.

9. A method for repairing a COB display module based on thermal lamination encapsulation technology according to claim 1, characterized in that, The curing temperature during the curing process is 130-160℃, and the curing time is 30-90 minutes.

10. A method for repairing a COB display module based on thermal lamination encapsulation technology according to claim 2, characterized in that, The peeling operation is to peel off the first protective film (100) on the surface of the repair film after cooling.

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