Manufacturing method of composite film, composite film and pseudo soldering detection and repair method

Abstract

The invention discloses a manufacturing method of a composite film, the composite film and a pseudo soldering detection and repair method, and belongs to the field of MLED display. The technical problems of low pseudo soldering detection and repair efficiency and high cost of the MLED device are solved. According to the technical scheme, the manufacturing method of the composite film comprises the following steps that a high-temperature-resistant film is manufactured, the high-temperature-resistant film is coated with a welding spot detection film, the welding spot detection film is coated with an SMP solution embedded with a self-repairing agent, an SMP film is formed on the welding spot detection film after drying and curing treatment, and the composite film is obtained after drying and curing treatment. The composite membrane is prepared by the preparation method of the composite membrane. The method comprises the steps that a target substrate covered with a composite film is fed into a die bonding device, an MLED chip is welded to a bonding pad of the target substrate, in the process, the color, located in a pseudo soldering point area, on an SMP film changes, so that the position of a pseudo soldering point is recognized, and then the pseudo soldering point is repaired in a laser heating mode; the invention is applied to MLED display.

Description

Technical Field

[0001] The invention provides a method for manufacturing a composite film, a composite film and a method for detecting and repairing a cold solder joint, and belongs to the technical field of MLED display. Background Art

[0002] In the manufacturing process of MLED (Micro / Mini LED), the die bonding process is to accurately place the tiny LED chip on the PCB board and fix it through welding technology. However, due to the extremely small size of MLED chips (usually 10~100μm), the problem of cold solder joints is more prominent during the welding process, which may cause the MLED module to fail or have poor quality. Traditional methods of detecting cold solder joints rely on manual visual inspection, X-ray imaging, ultrasonic monitoring, etc., but these methods of detecting cold solder joints have problems such as low detection efficiency, high cost, and difficulty in real-time detection. At the same time, the repair of cold solder joints usually requires manual rework, which increases production time and cost.

[0003] In recent years, with the development of smart materials, shape memory polymers (SMP) have gradually been applied to the field of cold solder joint detection and repair due to their unique temperature response characteristics. However, existing solutions can only achieve a single function, that is, either detecting cold solder joints or repairing them, and lack integrated solutions. Therefore, it is of great practical significance to develop a composite material screening membrane that can simultaneously achieve cold solder joint detection and repair, especially in MLED manufacturing, which can significantly improve production efficiency and product quality. Summary of the invention

[0004] In order to solve the technical problems of low efficiency and high cost in the prior art of detecting and repairing cold solder joints of MLED devices, the present invention proposes a method for preparing a composite film, a composite film, and a method for detecting and repairing cold solder joints. The purpose is to provide a composite film that can detect cold solder joints and self-repair cold solder joints at the same time.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a composite film, comprising the following steps: Step S11, preparing a high temperature resistant film; Step S12, coating a solder joint detection solution on the high temperature resistant film, and forming a solder joint detection film on the high temperature resistant film through drying and curing; Step S13, coating the SMP solution embedded with the self-repairing agent on the solder joint detection film, forming an SMP film on the solder joint detection film through drying and curing treatment, and finally obtaining a composite film consisting of a high temperature resistant film, a solder joint detection film and an SMP film.

[0006] Furthermore, the high temperature resistant film is made of any one of polyimide, alumina ceramic or polytetrafluoroethylene; the solder joint detection film is made of copper phthalocyanine or iron phthalocyanine thermosensitive material; the SMP film is made of any one of polyethylene-co-acrylate, polyvinyl alcohol or polyisoprene shape memory polymer materials.

[0007] Furthermore, the self-repairing agent comprises solder particles, conductive nanoparticles and chemical reaction substances, and the self-repairing agent is placed in a microcapsule.

[0008] Furthermore, the high temperature film is prepared by a sol-gel method, comprising the following steps: A1, preparing a monomer of polyimide by condensation reaction of pyromellitic acid diamine and pyromellitic acid dianhydride, and then generating polyamic acid by melt polycondensation reaction at a preset temperature and in the absence of water; A2, dissolving the synthesized polyamic acid in N-methylpyrrolidone liquid to prepare a polyamic acid solution; A3, coating the polyamic acid solution on the flat surface of the glass substrate to form a polyamic acid film on the glass substrate; A4, heat treating the coated polyamic acid film to dehydrate and cyclize the polyamic acid to obtain a polyimide film; A5. Peeling the polyimide film off the glass substrate, and obtaining a high temperature resistant film through post-processing.

[0009] Furthermore, the high temperature resistant film is prepared by chemical vapor deposition, comprising the following steps: B1. Fully mix the alumina ceramic powder, water and dispersant, and use an ultrasonic disperser to prepare an alumina ceramic suspension; B2, coating the alumina ceramic suspension on the glass substrate by spraying technology; B3, placing the glass substrate coated with the alumina ceramic suspension into an oven for drying to obtain an alumina ceramic; B4. Sinter alumina ceramics to obtain a high temperature resistant film.

[0010] Furthermore, the method for making the solder joint detection film comprises the following steps: C1. Add copper phthalocyanine powder to benzophenone and stir with a magnetic stirrer until the copper phthalocyanine is completely dissolved to obtain a copper phthalocyanine solution 1; or add the copper phthalocyanine powder to N,N-dimethylformamide to obtain a copper phthalocyanine solution 2; C2, evenly coating the copper phthalocyanine solution 1 or the copper phthalocyanine solution 2 on the high temperature resistant film; C3. Place in an oven for drying and curing to form a solder joint detection film on the high temperature resistant film.

[0011] Further, the method for preparing the SMP membrane comprises the following steps: E1. Microcapsule preparation: The self-healing agent was encapsulated in gelatin microcapsules by emulsification-coacervation method; E2. Solvent preparation: dissolving polyvinyl alcohol in ethanol to obtain a polyvinyl alcohol solution; or dissolving polyethylene-co-acrylate in acetone to obtain a polyethylene-co-acrylate solution; E3. Preparation of SMP solution: dispersing gelatin microcapsules encapsulating the self-healing agent in a polyvinyl alcohol solution or a polyethylene-co-acrylate solution, and stirring evenly with a magnetic stirrer to obtain an SMP solution; E4, coating: coating the SMP solution on the solder joint inspection film; E5, curing: put it into an oven for drying and curing to form an SMP film on the solder joint inspection film; E6. Shape memory training: The cured SMP film is made into a preset shape within a set temperature, and then cooled to room temperature to fix the shape.

[0012] Furthermore, the conductive nanoparticles are silver nanoparticles and / or gold nanoparticles; and the chemical reaction substances include bismuth sulfide and a silane coupling agent.

[0013] A composite membrane is manufactured by the above-mentioned composite membrane manufacturing method.

[0014] A method for detecting and repairing cold solder joints comprises the following steps: Step S21, preparing the composite membrane as described above; Step S22, covering the composite film on the target substrate so that the SMP film is in contact with the target substrate; Step S23, sending the target substrate covered with the composite film into a die bonding device to implement die bonding. When the MLED chip is soldered to the pad of the target substrate, the color of the cold solder joint area on the solder joint detection film will change, and the area where the color changes is the cold solder joint position; Step S24, using laser heating to heat the position of the cold solder joint marked on the composite film. During the heating process, the SMP film returns to a preset shape to repair the deformation or cracks of the solder joint, and releases the self-healing agent in the microcapsule. The self-healing agent interacts with the solder at the cold solder joint on the pad to complete the repair of the cold solder joint.

[0015] The beneficial effects of the present invention compared with the prior art are as follows: 1. The composite film of the present invention is composed of a layered structure of a high-temperature resistant film, an SMP film and a solder joint detection film. The composite film is placed on a target substrate so that the SMP film contacts the MLED chip on the target substrate. Then, the target substrate with the composite film is sent to a reflow soldering furnace for solid crystal. During this process, due to the poor heat conduction of the cold solder joint, its temperature is abnormal, and the color of the solder joint detection film can change within the abnormal temperature range, thereby achieving the purpose of detecting the position of the cold solder joint. Then, a laser heating device is used to heat the position of the cold solder joint. At a set temperature, the SMP film is restored to a preset shape, the deformation or crack of the solder joint is repaired, and the self-repairing agent therein is released. At the same time, the high-temperature resistant layer at the cold solder joint is destroyed or the high-temperature resistant layer at the cold solder joint can penetrate the self-repairing agent at the set temperature. The self-repairing agent flows to the cold solder joint for repair, thereby realizing the function of detecting the cold solder joint and repairing the cold solder joint at the same time, thereby ensuring the welding quality of the MLED chip. The composite film of the present invention is low in cost, thereby greatly reducing the cost of detecting and repairing the cold solder joint. 2. The present invention sends the target substrate covered with the composite film into a reflow oven for die bonding, can mark the location of the cold solder joints while bonding the crystals, and uses laser heating to achieve self-repair of the cold solder joints. The operation process is simple, and the production efficiency of the MLED device is effectively improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below in conjunction with the accompanying drawings: Figure 1 It is a schematic diagram of the composite membrane structure of the present invention; Figure 2 is a schematic cross-sectional view of the composite membrane of the present invention; Figure 3 It is a schematic diagram of the structure of the composite film of the present invention cooperating with the target substrate; Figure 4 It is a schematic diagram of the process of detecting cold solder joints by the solder joint detection film when the composite film of the present invention passes through a reflow soldering furnace; Figure 5 Schematic diagram of the process of repairing a cold solder joint using the SMP membrane of the present invention; Figure 6 A schematic diagram of a target substrate after the composite film is peeled off after the repair of the virtual solder joint is completed in the present invention; In the figure: 1 is a high temperature resistant film, 2 is a solder joint detection film, 3 is an SMP film, 5 is a solder pad, 6 is a target substrate, 7 is an MLED chip, 8 is a composite film, 9 is a cold solder joint location, and 10 is a laser heating device. DETAILED DESCRIPTION

[0017] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate relative positions or positional relationships, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0018] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0019] like Figures 1 to 6 As shown, the present invention provides a method for preparing a composite film, comprising the following steps: Step S11, making a high-temperature resistant film 1 by a sol-gel method or a chemical vapor deposition method; the high-temperature resistant film 1 is made of a high-temperature resistant material such as polyimide or polytetrafluoroethylene or alumina ceramics, and is used to protect the composite film 8 of the present invention from being damaged when passing through a crystal bonding device; the crystal bonding device in this embodiment is a reflow oven.

[0020] Step S12, coating the solder joint detection solution on the high temperature resistant film 1, and forming the solder joint detection film 2 on the high temperature resistant film 1 after drying and curing, and the solder joint detection film 2 is made of a thermosensitive material such as copper phthalocyanine or iron phthalocyanine. Due to the poor thermal conductivity of the cold solder joint, which is specifically manifested as abnormal temperature, the color of the thermosensitive material will change at the abnormal temperature, and the location of the cold solder joint can be detected by distinguishing the colors of different areas on the solder joint detection film 2.

[0021] Step S13, coating a shape memory polymer (hereinafter referred to as SMP) solution embedded with a self-healing agent on the solder joint detection film 2, and forming an SMP film 3 on the solder joint detection film 2 after drying and curing, and obtaining a composite film 8 after drying and curing again. The high temperature resistant film 1, the solder joint detection film 2 and the SMP film 3 constitute a layered structure, the outermost layer is the SMP film 3, the middle layer is the solder joint detection film 2, and the inner layer is the high temperature resistant film 1, wherein the SMP film 3 is in contact with the target substrate 6. The SMP film 3 is made of shape memory polymer materials such as polyethylene-co-acrylate or polyvinyl alcohol or polyisoprene. The self-healing agent includes solder particles, conductive nanoparticles, and chemical reaction substances, and the self-healing agent is placed in a gelatin microcapsule, wherein the conductive nanoparticles are silver nanoparticles and / or gold nanoparticles, and the chemical reaction substances include bismuth sulfide and a silane coupling agent. This type of shape memory polymer material can control the cross-linking structure of the SMP film 3 when subjected to external stimuli, such as heat, light, electricity, mechanical force, etc., so that the SMP film 3 can be restored to a preset shape, thereby achieving a shape memory effect and repairing solder joint deformation or cracks. The self-healing agent in the gelatin microcapsule reacts with the solder to form a new solder joint, and chemically repairs the cold solder joint, thereby achieving self-healing capability.

[0022] The coating method mentioned above is any one of coating, spin coating, knife coating, roller coating or spray coating.

[0023] Specifically, when the high temperature resistant film 1 is prepared by a sol-gel method, the following steps are included: A1. Prepare a monomer of polyimide by condensation reaction of pyromellitic acid diamine (PPTA) and pyromellitic acid dianhydride (PMDA), and then generate a prepolymer of polyimide, polyamic acid (PAA), by melt polycondensation reaction under low temperature and anhydrous conditions; in this embodiment, low temperature refers to below 80° C., and those skilled in the art can make adaptive adjustments according to different high temperature resistant materials selected or different applicable environments; A2, dissolving the synthesized polyamic acid in N-methylpyrrolidone (NMP) liquid to prepare a polyamic acid solution; A3, coating the polyamic acid solution on the flat surface of the glass substrate to form a polyamic acid film on the glass substrate; A4, heat-treating the coated polyamic acid film to dehydrate and cyclize the polyamic acid to obtain a polyimide film; in this embodiment, the temperature range of the heat treatment of the coated polyamic acid film is 250° C. to 350° C., and those skilled in the art can make adaptive adjustments according to different high-temperature resistant materials selected or different applicable environments; A5. Peeling the polyimide film off the glass substrate, and obtaining the high temperature resistant film 1 through post-processing, wherein the post-processing includes heat setting, solvent washing, drying and other processes to further improve the performance of the high temperature resistant film 1.

[0024] When the high temperature resistant film 1 is prepared by chemical vapor deposition, the following steps are included: B1. Fully mix the alumina ceramic powder, water and dispersant, and use an ultrasonic disperser to prepare an alumina ceramic suspension; B2. Coating the alumina ceramic suspension on the glass substrate by spraying technology. In this embodiment, the coating thickness ranges from 10 to 50 μm; B3. Put the glass substrate coated with the alumina ceramic suspension into an oven for drying to obtain an alumina ceramic. In this embodiment, the method for drying the alumina ceramic suspension is to first set the temperature in the oven to 80° C., dry for 1 hour, and then increase the temperature in the oven to 150° C. and dry for 2 hours. B4. Sintering alumina ceramics to obtain a high temperature resistant film 1. In this embodiment, the temperature for sintering alumina ceramics is about 900°C.

[0025] The method for making the solder joint detection film 2 comprises the following steps: C1. Add copper phthalocyanine powder to benzophenone (concentration of 1-10 wt%), and stir with a magnetic stirrer until the copper phthalocyanine is completely dissolved to obtain a copper phthalocyanine solution; C2, evenly coating the copper phthalocyanine solution on the high temperature resistant film 1, with a coating thickness ranging from 10 to 30 μm; C 3. Place the solution in an oven for drying and curing to obtain a solder joint detection film 2; the method for drying and curing the copper phthalocyanine solution is to slowly increase the temperature in the oven to 50-100°C and dry for 12 hours to remove the solvent; C4. The obtained solder joint detection film 2 is placed in a vacuum dryer for heat treatment to improve the adhesion and thermal stability of the solder joint detection film 2. The temperature range of the heat treatment is 100-300°C.

[0026] The solder joint detection film 2 can also be made by the following steps: D1. Add copper phthalocyanine powder to N,N-dimethylformamide to obtain a copper phthalocyanine solution, wherein the concentration of the copper phthalocyanine solution is in the range of 1% to 5%; D2, coating the copper phthalocyanine solution on the high temperature resistant film 1 by drop coating or spin coating technology, with the coating thickness ranging from 5 to 10 μm; D3. Place the film in an oven for drying and curing to obtain a solder joint detection film 2; the drying temperature is 60°C, the drying time is 30 minutes, and the film is heat treated at 100°C for 10 minutes to cure the solder joint detection film 2.

[0027] The method for making the SMP film 3 comprises the following steps: E1. Microcapsule preparation: The self-healing agent was encapsulated in gelatin microcapsules by emulsification-coacervation method; E2. Solvent preparation: dissolve polyvinyl alcohol in ethanol to obtain a polyvinyl alcohol solution, the concentration of which is 10%; E3. Preparation of SMP solution: dispersing the gelatin microcapsules encapsulating the self-healing agent in the polyvinyl alcohol solution, so that the ratio of the polyvinyl alcohol solution to the gelatin microcapsules encapsulating the self-healing agent is 100:1, and then stirring evenly with a magnetic stirrer to obtain an SMP solution; E4, coating: the SMP solution is coated on the solder joint detection film 2 by a solution coating method, and the coating thickness ranges from 50 to 100 μm; E5, curing: placing in an oven for drying and curing to form an SMP film 3 on the solder joint detection film 2. In this embodiment, the drying temperature is 120° C., which can also be adjusted according to actual conditions to remove the solvent to form an SMP film 3 of a set thickness; E6. Shape memory training: The cured SMP film 3 is formed into a preset shape in an environment of 300° C., and then cooled to room temperature to fix the shape.

[0028] The SMP membrane 3 can also be produced by the following steps: F1. Microcapsule preparation: The self-healing agent is encapsulated in gelatin microcapsules by emulsification-coacervation method; F2. Solvent preparation: dissolve polyethylene-co-acrylate in acetone to obtain a polyethylene-co-acrylate solution, wherein the concentration of the polyethylene-co-acrylate solution is 5-10%; F3, SMP solution preparation: dispersing the gelatin microcapsules encapsulating the self-healing agent in the polyethylene-co-acrylate solution, stirring evenly with a magnetic stirrer to obtain an SMP solution; F4, coating: coating the SMP solution on the solder joint detection film 2, with the coating thickness ranging from 50 to 100 μm; F5, curing: placing the solution in an oven for drying and curing to form an SMP film 3 on the solder joint detection film 2; the method for drying the SMP solution in this embodiment is to first set the temperature in the oven to 120°C, and then increase the temperature in the oven to 200°C for curing for 1 hour after drying for 2 hours; F6. Shape memory training: The cured SMP film 3 is formed into a preset shape in an environment of 300° C., and then cooled to room temperature to fix the shape.

[0029] The temperature values, concentration values ​​and thickness values ​​involved in this application are all obtained according to experimental conditions in specific embodiments. If technicians in this field use other high-temperature resistant materials, thermosensitive materials and shape memory polymer materials, they can be adjusted according to the implementation environment and the characteristics of the materials themselves, so as to ensure that the manufactured high-temperature resistant film 1 can ensure that the composite film 8 of the present invention is not damaged when passing through the reflow soldering furnace, the self-healing agent released by the SMP film 3 when heated by the laser can repair the cold solder joints through the high-temperature resistant film 1, and the solder joint detection film 2 can accurately detect the position 9 of the cold solder joints.

[0030] The present invention further provides a composite film, which is made by the manufacturing method of the composite film 8 . The composite film 8 of the present invention can be used for detecting and repairing tiny solder joints, ensuring the soldering quality of each MLED chip 7 .

[0031] The present invention also provides a method for detecting and repairing cold solder joints, which is characterized by comprising the following steps: Step S21, preparing the above-mentioned composite film 8; Step S22, covering the composite film 8 on the target substrate 6, so that the SMP film 3 is in contact with the target substrate 6; the target substrate 6 is the MLED substrate after crystal bonding; Step S23, sending the target substrate 6 covered with the composite film 8 into the reflow oven, and soldering the MLED chip 7 to the solder pad 5 of the target substrate 6. Due to the abnormal temperature of the cold solder joint, if there is a cold solder joint on the target substrate 6 during this process, the color of a part of the area on the solder joint detection film 2 will change, and the area where the color changes is the cold solder joint position 9; Step S24, using the laser heating device 10 to locally heat the virtual solder joint position 9 marked on the composite film 8, during the heating process, the SMP film 3 returns to the preset shape to repair the deformation or crack of the solder joint, and releases the repair agent in the microcapsule, and the self-repairing agent interacts with the solder at the virtual solder joint on the pad 5 to complete the repair of the virtual solder joint. When the SMP film 3 is made of polyvinyl alcohol material, the laser heating temperature is selected to be 350°C, when the SMP film 3 is made of polyethylene-co-acrylate material, the laser heating temperature is selected to be 280°C, when the SMP film 3 is made of other shape memory polymer materials, the temperature range of the laser heating is adjusted according to the characteristics of the shape memory polymer material itself, so that the self-repairing agent released by the SMP film 3 when it is heated by the laser can repair the virtual solder joint through the high temperature resistant film 1.

[0032] Step S25 , after the repair of the cold solder joints is completed, the cold solder joint screening film is peeled off and the subsequent MLED packaging process is performed.

[0033] In the present invention, covering the composite film 8 on the target substrate 6 means placing the composite film 8 on the target substrate 6. If the stability of the composite film 8 during operation is to be improved, the composite film 8 can be adhered to the target substrate 6, but it is necessary to ensure that the composite film 8 can be successfully removed from the target substrate 6 after the repair of the cold solder joint is completed, and the target substrate 6 cannot be contaminated.

[0034] The temperature of laser heating is higher than the shape transition temperature of the SMP film 3 .

[0035] The heat-resistant temperature of the high-temperature resistant film 1 is higher than the soldering temperature during the reflow soldering process.

[0036] In some special cases, such as under high temperature conditions or using special solders, alumina ceramic films will have a certain degree of permeation. During the sintering process, as the temperature rises, the gaps between the ceramic powder particles will gradually decrease, and the particles will bond and diffuse, eventually forming a dense ceramic structure. However, during the sintering process, if there is an appropriate amount of additives or the sintering temperature and time are properly controlled, a certain number of micropores can be retained or generated inside the ceramic. The presence of these micropores can give alumina ceramics some special properties, such as lower density, higher thermal insulation and sound absorption properties.

[0037] The temperature range of the reflow soldering process mainly includes the temperature settings of the preheating zone, constant temperature zone, reflow soldering zone and cooling zone. The temperature of the preheating zone of the reflow soldering is set between 130 and 190°C, and the time is generally 80 to 120 seconds. The specific temperature and time of the constant temperature zone need to be adjusted according to the actual product and equipment environment. The temperature range is usually between 150 and 200°C, and the time range is 60 to 120 seconds; the temperature of the reflow soldering zone is controlled between 220 and 260°C, and the duration is 60 to 90 seconds. The cooling rate of the cooling zone is generally around 4°C / S.

[0038] The working principle of the present invention is: The composite film 8 is covered on the target substrate 6 so that the SMP film 3 is in contact with the target substrate 6, and the target substrate 6 covered with the composite film 8 is sent to the reflow furnace to realize solid crystal. When the MLED chip 7 is soldered to the pad 5 of the target substrate 6, if there is a cold solder joint on the target substrate 6, the color of a part of the area on the solder joint detection film 2 will change, and the position where the color change occurs is the position of the cold solder joint, thereby achieving the purpose of detecting the cold solder joint position 9; then the cold solder joint position 9 is heated by a laser heating device 10, and the SMP film 3 can be restored to a preset shape at a set temperature to repair slight solder joint deformation or cracks, and release the self-repairing agent therein for chemical repair. In this process, the high temperature resistant layer at the cold solder joint is destroyed or the high temperature resistant layer at the cold solder joint can penetrate the self-repairing agent at the set temperature, and the self-repairing agent flows to the cold solder joint for repair.

[0039] Regarding the specific structure of the present invention, it should be noted that the connection relationship between the various component modules adopted in the present invention is definite and feasible. Except for special instructions in the embodiments, the specific connection relationship can bring about corresponding technical effects, and solve the technical problems raised by the present invention without relying on the execution of corresponding software programs. The components, modules, models of specific components, the connection methods between each other, and the conventional use methods and expected technical effects brought about by the above-mentioned technical features, except for specific instructions, all belong to the disclosed contents in patents, journal articles, technical manuals, technical dictionaries, and textbooks that can be obtained by technical personnel in this field before the application date, or belong to the existing technologies such as conventional technologies and common knowledge in this field, and there is no need to elaborate, so that the technical solution provided in this case is clear, complete, and feasible, and the corresponding physical products can be reproduced or obtained according to the technical means.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a composite film, characterized in that: The following steps are involved: Step S11, preparing a high temperature resistant film (1); Step S12, coating a solder joint detection solution on the high temperature resistant film (1), and forming a solder joint detection film (2) on the high temperature resistant film (1) through drying and curing. Step S13, coating the SMP solution embedded with the self-repairing agent on the solder joint detection film (2), and forming an SMP film (3) on the solder joint detection film (2) through drying and curing treatment, and finally obtaining a composite film (8).

2. The method for preparing a composite film according to claim 1, characterized in that: The high temperature resistant film (1) is made of any one of polyimide, alumina ceramic or polytetrafluoroethylene; the solder joint detection film (2) is made of copper phthalocyanine or iron phthalocyanine thermosensitive material; and the SMP film (3) is made of any one of polyethylene-co-acrylate, polyvinyl alcohol or polyisoprene shape memory polymer material.

3. The method for preparing a composite film according to claim 1, characterized in that: The self-repairing agent comprises solder particles, conductive nanoparticles and chemical reaction substances, and the self-repairing agent is placed in microcapsules.

4. The method for preparing a composite film according to claim 1, characterized in that: The high temperature film is prepared by a sol-gel method, comprising the following steps: A1, preparing a monomer of polyimide by condensation reaction of pyromellitic acid diamine and pyromellitic acid dianhydride, and then generating polyamic acid by melt polycondensation reaction at a preset temperature and in the absence of water; A2, dissolving the synthesized polyamic acid in N-methylpyrrolidone liquid to prepare a polyamic acid solution; A3, coating the polyamic acid solution on the flat surface of the glass substrate to form a polyamic acid film on the glass substrate; A4, heat treating the coated polyamic acid film to dehydrate and cyclize the polyamic acid to obtain a polyimide film; A5. Peeling the polyimide film off the glass substrate, and obtaining a high temperature resistant film (1) through post-processing.

5. The method for preparing a composite film according to claim 1, characterized in that: The high temperature resistant film (1) is prepared by a chemical vapor deposition method, comprising the following steps: B1. Fully mix the alumina ceramic powder, water and dispersant, and use an ultrasonic disperser to prepare an alumina ceramic suspension; B2, coating the alumina ceramic suspension on the glass substrate by spraying technology; B3, placing the glass substrate coated with the alumina ceramic suspension into an oven for drying to obtain an alumina ceramic; B4. Sintering alumina ceramics to obtain a high temperature resistant film (1).

6. The method for preparing a composite membrane according to claim 1, characterized in that: The method for manufacturing the solder joint detection film (2) comprises the following steps: C1. Add copper phthalocyanine powder to benzophenone and stir with a magnetic stirrer until the copper phthalocyanine is completely dissolved to obtain a copper phthalocyanine solution 1; or add the copper phthalocyanine powder to N,N-dimethylformamide to obtain a copper phthalocyanine solution 2; C2, evenly coating the copper phthalocyanine solution 1 or the copper phthalocyanine solution 2 on the high temperature resistant film (1); C3. Place the film in an oven for drying and curing to form a solder joint detection film (2) on the high temperature resistant film (1).

7. The method for preparing a composite membrane according to claim 1, characterized in that: The method for preparing the SMP film (3) comprises the following steps: E1. Microcapsule preparation: The self-healing agent was encapsulated in gelatin microcapsules by emulsification-coacervation method; E2. Solvent preparation: dissolving polyvinyl alcohol in ethanol to obtain a polyvinyl alcohol solution; or dissolving polyethylene-co-acrylate in acetone to obtain a polyethylene-co-acrylate solution; E3. Preparation of SMP solution: dispersing gelatin microcapsules encapsulating the self-healing agent in a polyvinyl alcohol solution or a polyethylene-co-acrylate solution, and stirring evenly with a magnetic stirrer to obtain an SMP solution; E4, coating: coating the SMP solution on the solder joint detection film (2); E5, curing: placing in an oven for drying and curing to form an SMP film (3) on the solder joint inspection film (2); E6. Shape memory training: The cured SMP film (3) is formed into a preset shape within a set temperature, and then cooled to room temperature to fix the shape.

8. The method for making a composite film according to claim 3, characterized in that: The conductive nanoparticles are silver nanoparticles and / or gold nanoparticles; the chemical reaction substances include bismuth sulfide and a silane coupling agent.

9. A composite film, characterized in that: The composite membrane (8) is made by a composite membrane making method according to any one of claims 1 to 8.

10. A method for detecting and repairing cold solder joints, characterized in that: The following steps are involved: Step S21, preparing the composite film (8) as claimed in claim 9; Step S22, covering the composite film (8) on the target substrate (6) so that the SMP film (3) is in contact with the target substrate (6); Step S23, sending the target substrate (6) covered with the composite film (8) into a die bonding device to achieve die bonding, when the MLED chip (7) is soldered to the solder pad (5) of the target substrate (6), the color of the cold solder joint area on the solder joint detection film (2) will change, and the area where the color changes is the cold solder joint position (9); Step S24, using laser heating to heat the marked cold solder joint position (9) on the composite film (8), during which the SMP film (3) returns to a preset shape to repair the deformation or crack of the solder joint, and releases the self-repairing agent in the microcapsule, and the self-repairing agent interacts with the solder at the cold solder joint on the pad (5), thereby completing the repair of the cold solder joint.

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