FPC insulation structure with sheet-shaped jumper and preparation method thereof

Abstract

The application relates to an FPC insulation structure with sheet-shaped jumpers and a preparation method thereof, and relates to the technical field of printed circuit boards. The FPC insulation structure comprises an FPC body, a flexible base material and a plurality of sheet-shaped jumpers. The flexible base material is integrated with a conductive circuit. The conductive circuit is provided with a plurality of jumper starting points and a plurality of jumper ending points. The sheet-shaped jumpers are arranged on one side of the flexible base material. One end of the sheet-shaped jumper is connected with the corresponding jumper starting point, and the other end is connected with the corresponding jumper ending point. A plurality of local insulation coatings are formed on the flexible base material through vapor deposition. The local insulation coatings cover the corresponding jumper starting points, the sheet-shaped jumpers and the jumper ending points. An overall insulation coating is fixedly arranged on the flexible base material. The plurality of local insulation coatings are located between the overall insulation coating and the flexible base material, and the local insulation coatings are fixedly connected with the overall insulation coating. The application can improve the insulation integrity and use reliability of the FPC insulation structure under the conditions of high temperature, high humidity, repeated bending and live operation.

Description

Technical Field

[0001] This application relates to the technical field of printed circuit boards, and in particular to an FPC insulation structure with sheet-like jumpers and a method for preparing the same. Background Technology

[0002] Flexible printed circuit boards (FPCs) are widely used in many fields due to their bendability, thinness, and flexible wiring, such as automotive lighting equipment, aviation or ferry display equipment, and consumer electronics.

[0003] Because FPCs have many applications, in some aviation, ferry or other usage scenarios, FPCs not only need to withstand repeated bending, but also sometimes in harsh working conditions such as low temperature, high temperature, high humidity, and may even operate for a long time under power-on conditions. This puts forward high requirements for the insulation performance and environmental adaptability of FPCs.

[0004] Currently, the insulation design of existing FPCs typically involves spraying an insulating layer or covering the entire FPC surface with an insulating film to insulate and isolate the circuitry on the FPC from the external environment.

[0005] To achieve electrical connections within a limited space, existing FPCs often incorporate cross-connection structures, with sheet jumpers being a common example. For instance, a sheet jumper is added between mutually insulated lines, connecting them to achieve electrical continuity. For FPCs equipped with sheet jumpers, the insulation design also employs the aforementioned method of spraying an insulating layer or covering with an insulating film.

[0006] Regarding the aforementioned technologies, when a patch cord is installed on an FPC, a step appears at the connection between the patch cord and the FPC substrate. This makes it difficult for the insulating layer or film to form a sufficient, dense, and continuous bond at the step location after the insulating layer or film is applied. Consequently, weak insulation areas easily form at the edges of the patch cord and at the connection between the patch cord and the FPC substrate. Under conditions of high temperature, high humidity, repeated bending, or live operation, the insulating layer or film in these weak insulation areas is prone to damage, becoming the starting point of insulation failure and thus affecting the insulation reliability of the corresponding patch cord area. Summary of the Invention

[0007] This application provides an FPC insulation structure with sheet-like jumpers and its preparation method, the purpose of which is to improve the insulation integrity, environmental barrier capability, and reliability of the sheet-like jumper area on the FPC under high temperature, high humidity, repeated bending and live operation conditions.

[0008] Firstly, the FPC insulation structure with sheet-like jumpers provided in this application adopts the following technical solution: An FPC insulation structure with sheet-like jumpers, comprising: The FPC body includes a flexible substrate and several sheet jumpers. The flexible substrate has integrated conductive lines, and the conductive lines are provided with several bridging start points and several bridging end points. The sheet jumpers are disposed on one side of the flexible substrate. The bridging start points, the sheet jumpers and the bridging end points are arranged in a one-to-one correspondence. One end of the sheet jumper is connected to the corresponding bridging start point and the other end is connected to the corresponding bridging end point. Several partial insulating films are formed on the flexible substrate by vapor deposition. The partial insulating films are arranged in a one-to-one correspondence with the sheet jumpers. The partial insulating films cover the corresponding jumper start point, the sheet jumper and the jumper end point. An overall insulating coating is fixed and covers the flexible substrate, and a plurality of partial insulating films are located between the overall insulating coating and the flexible substrate, and the partial insulating films are fixedly connected to the overall insulating coating.

[0009] By adopting the above technical solution, the sheet jumper can achieve cross-line conduction between the bridging start point and the bridging end point, so that the FPC body can still complete the bridging connection within the limited wiring space; after the sheet jumper is placed on the surface of the flexible substrate, its edge and the transition area between it and the flexible substrate usually form a stepped transition area, which is more likely to become a weak point in insulation coverage than the planar area.

[0010] Based on this, a local insulation film is first set in the area corresponding to the patch cord, so that the local insulation film can cover the starting point of the bridging, the patch cord and the ending point of the bridging, and can form local insulation protection for the key area where the patch cord is located.

[0011] Then, the flexible substrate is completely covered by an overall insulating coating, so that the local insulating film is located between the overall insulating coating and the flexible substrate, thereby forming a continuous outer insulating encapsulation in addition to local key protection.

[0012] Therefore, the combination of local insulation film and overall insulation coating can form an insulation structure that combines local reinforcement and overall encapsulation in the patch cord area. This not only helps to improve the continuity of insulation coverage at the step transition position, but also helps to reduce the possibility of external moisture, dust or corrosive media intruding from weak insulation positions, thereby improving the insulation reliability and long-term stability of the patch cord area.

[0013] Optionally, a dense insulating film is fixed to the outer surface of the sheet-like jumper, and the dense insulating film wraps around the sheet-like jumper.

[0014] By adopting the above technical solution, a dense insulating film is pre-set on the outer surface of the sheet jumper, which directly wraps the sheet jumper, thereby reducing the area of ​​the sheet jumper directly exposed to the external environment during assembly, storage or use.

[0015] Meanwhile, the dense insulating film, the corresponding local insulating film, and the overall insulating coating can form a multi-layered insulating protection relationship, which is conducive to further improving the insulation barrier capability of the sheet jumper.

[0016] Optionally, the dense insulating film has exposed windows at both ends corresponding to the sheet jumper, and the exposed windows are located on the side of the sheet jumper facing the flexible substrate.

[0017] By adopting the above technical solution and setting exposed windows at both ends of the sheet-like jumper, the connection areas of the sheet-like jumper and the starting and ending points of the bridging can be kept electrically exposed, thus ensuring that the sheet-like jumper can still perform its electrical connection function. Based on this structure, the insulation risk caused by direct exposure of the main body area of ​​the sheet-like jumper can be reduced, and the dense insulating film can be avoided from obstructing the connection at the end of the sheet-like jumper, thereby balancing insulation and conductivity.

[0018] Optionally, an adhesive layer is fixed to the outside of the dense insulating film, and the partial insulating film is fixedly connected to the corresponding adhesive layer.

[0019] By adopting the above technical solution, the binder layer is placed between the dense insulating film and the partial insulating coating, which can build an interface connection transition layer between the dense insulating film and the partial insulating coating.

[0020] Since the dense insulating film and the partial insulating coating usually use different material systems, there is a possibility of insufficient interface adhesion or easy peeling under stress when they are in direct contact. The addition of the binder layer can improve the adhesion and bonding of the outer partial insulating coating to the inner dense insulating film, making it easier for the partial insulating coating to form a stable cover on the surface of the sheet jumper.

[0021] With this design, the interlayer connection between the local insulating film and the sheet jumper is more stable under bending, hot and cold cycling or humid conditions, and it is less likely to form delamination, curling or cracks at the interface.

[0022] Optionally, an intermediate layer is provided between the partial insulating film and the overall insulating coating, the partial insulating film, the intermediate layer and the overall insulating coating are connected in sequence, and the elastic modulus of the partial insulating film, the intermediate layer and the overall insulating coating decreases in sequence.

[0023] By adopting the above technical solution, the local insulating film and the overall insulating coating respectively undertake the functions of local key insulation and overall insulating encapsulation. However, the local insulating film and the overall insulating coating may have differences in rigidity and flexibility in their material properties. Therefore, when the local insulating film and the overall insulating coating are directly connected and fixed, when the FPC needs to be bent or there is a significant temperature change in the environment, the interface between the local insulating film and the overall insulating coating is prone to large concentrated stress due to inconsistent deformation, which may lead to separation of the local insulating film and the overall insulating coating, or even direct damage to the local insulating film and the overall insulating coating.

[0024] Based on this, by setting an intermediate layer between the local insulating film and the overall insulating coating, and by making the elastic modulus of the local insulating film, the intermediate layer and the overall insulating coating decrease sequentially, a transition structure with gradually changing modulus is formed, so that the interfacial stress no longer abruptly concentrates at a single connection interface, but can be gradually transmitted and buffered within the transition layer.

[0025] This helps reduce the risk of interlayer delamination, local cracking, and insulation failure, and improves the interlayer stability of multilayer insulation structures under bending and environmental change conditions.

[0026] Optionally, the intermediate layer includes a plurality of transition film layers, which are stacked and fixedly connected sequentially along the spacing direction between the local insulating film and the overall insulating coating. The local insulating film and the overall insulating coating are respectively fixedly connected to the corresponding adjacent transition film layers. Along the spacing direction between the local insulating film and the overall insulating coating, the elastic modulus of the local insulating film, the plurality of transition film layers and the overall insulating coating decreases sequentially.

[0027] By adopting the above technical solution, under the structural design of the intermediate layer, when there is a large performance difference between the local insulating film and the overall insulating coating, each transition film layer can respectively undertake part of the stress transmission and deformation coordination function, so that the mechanical response from the inside to the outside is more gradual, which can further improve the bending durability and interlayer bonding stability of the FPC insulation structure.

[0028] Optionally, a black cover film is provided on the side of the integral insulating coating that faces away from the flexible substrate, and the black cover film is fixedly connected to the integral insulating coating.

[0029] By adopting the above technical solution, since the overall insulating coating itself mainly serves as an insulating encapsulation layer, and external abrasion, pollution, moisture, and corrosive media usually act on the outermost surface first, the black cover film can act as an outer barrier to withstand the impact of the external environment, thereby reducing the degree of direct exposure of the overall insulating coating. This is beneficial to improving the surface integrity, abrasion resistance, and environmental barrier capabilities of the entire FPC insulation structure.

[0030] Optionally, the overall insulating coating includes a main flexible film and a plurality of reinforcing cover films. The main flexible film and the plurality of reinforcing cover films are both fixed on the flexible substrate. The plurality of reinforcing cover films are all fixedly connected to the main flexible film, and the thickness of the reinforcing cover film is greater than the thickness of the main flexible film. The reinforcing cover film is provided in a one-to-one correspondence with the local insulating film, and the reinforcing cover film covers the corresponding local insulating film. The reinforcing cover film is fixedly connected to the corresponding local insulating film.

[0031] By adopting the above technical solution, the overall insulating coating is divided into two parts: a main flexible film and a reinforcing cover film. The main flexible film covers most of the area, ensuring that the FPC as a whole still has good flexibility; the reinforcing cover film covers the corresponding areas of the insulating film, and its thickness is greater than that of the main flexible film, thus forming local thickening protection in the corresponding areas.

[0032] Optionally, some of the reinforcing cover films are integrally formed with the main flexible film.

[0033] By adopting the above technical solution, the reinforcing cover film and the main flexible film are integrally formed, which can reduce the possibility of obvious interface weaknesses at the connection boundary between the reinforcing cover film and the main flexible film, and reduce the risk of peeling and cracking along the connection boundary during bending, hot and cold cycles or long-term use.

[0034] Secondly, the method for preparing an FPC insulation structure with sheet-like jumpers provided in this application adopts the following technical solution: A method for preparing an FPC insulation structure with sheet-like jumpers, comprising the following steps: Obtain the FPC body and preprocess the FPC body; A local insulating film is formed in the corresponding area of ​​each sheet jumper on the FPC body, and the local insulating film covers the corresponding bridging start point, the sheet jumper and the bridging end point; An integral insulating coating is formed on the FPC body, such that the integral insulating coating covers the surface of the FPC body, and the partial insulating film is located between the integral insulating coating and the flexible substrate; The local insulating film and the overall insulating coating are cured.

[0035] By adopting the above technical solution, the FPC body is first obtained and pretreated, which helps to improve the cleanliness, dryness and interfacial activity of the FPC body surface, thus providing a better adhesion basis for the subsequent formation of the insulation layer. Then, a local insulating film is first formed in the corresponding area of ​​the patch cord, which can first focus on covering the patch cord and its connection area. Then, an overall insulating coating is formed on the entire surface of the FPC body, so that the local insulating film is located between the overall insulating coating and the flexible substrate, thereby obtaining a multi-layer insulation structure that combines local key protection and overall encapsulation. Finally, curing is used to make the local insulating film and the overall insulating coating form a stable bond with the FPC body.

[0036] Therefore, this preparation method can effectively achieve the layered construction of the aforementioned FPC insulation structure, enabling the local insulation enhancement of the patch jumper area and the overall board insulation encapsulation to be realized sequentially. This ensures the integrity of the insulation structure and the stability of the interlayer bonding from a process perspective, thereby improving the insulation reliability and long-term performance of the obtained FPC insulation structure under complex working conditions.

[0037] In summary, this application includes at least one of the following beneficial technical effects: 1. This application achieves an FPC insulation structure that combines localized key insulation with overall continuous encapsulation insulation by providing a localized insulating film on the area corresponding to the patch jumper on the flexible substrate, and forming an overall insulating coating covering the entire flexible substrate. The localized insulating film provides more targeted insulation protection for the edges of the patch jumper and the stepped transition area where it connects to the flexible substrate. Therefore, this FPC insulation structure design improves upon the problems of discontinuous insulation coverage and weak points in existing patch jumper areas, thereby enhancing the insulation integrity and reliability of the FPC insulation structure under high temperature, high humidity, repeated bending, and live operation conditions.

[0038] 2. By setting a dense insulating film, an exposed window, and an adhesive layer, this application enables the sheet jumper to have its own insulation protection while retaining the stable conductive connection capability at both ends of the sheet jumper, and enhances the interfacial adhesion stability between the local insulating film and the sheet jumper, thereby improving the interlayer bonding capability and long-term environmental adaptability of the multilayer insulation structure in the corresponding sheet jumper area.

[0039] 3. Through the structural design of the intermediate layer, the overall insulating coating and the black cover film, this application further enhances the multi-layer insulation structure of each sheet jumper area on the FPC insulation structure. The multi-layer insulation structure achieves synergistic enhancement in multiple aspects such as modulus transition, local thickening and outer protection, thereby further improving the overall insulation performance and long-term stability of the entire FPC insulation structure. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the overall structure of the FPC insulation structure of Embodiment 1 of this application.

[0041] Figure 2 This is a schematic diagram of the overall structure of the FPC body in Embodiment 1 of this application.

[0042] Figure 3 This is a schematic diagram illustrating the principle structure of the partial insulating film covering the corresponding sheet jumper in Embodiment 1 of this application.

[0043] Figure 4 This is a partial cross-sectional view of the FPC insulation structure of Embodiment 1 of this application at a single sheet jumper.

[0044] Figure 5 This is a schematic diagram of the bottom structure of the sheet jumper in Embodiment 2 of this application.

[0045] Figure 6 This is a cross-sectional view of the sheet jumper wire in Embodiment 2 of this application.

[0046] Figure 7 This is a cross-sectional structural diagram of the intermediate layer in Embodiment 3 of this application.

[0047] Figure 8 This is a partial cross-sectional view of the overall insulating coating of Embodiment 4 of this application.

[0048] Figure 9 This is a partial cross-sectional view of the FPC insulation structure of Embodiment 5 of this application at a single sheet jumper.

[0049] In the diagram, 1. FPC body; 11. Flexible substrate; 12. Conductive circuit; 121. Bridging start point; 122. Bridging end point; 13. Sheet jumper; 2. Partial insulating film; 3. Overall insulating coating; 31. Window; 32. Main flexible film; 33. Reinforcing cover film; 4. Dense insulating film; 41. Exposed window; 5. Adhesive layer; 6. Intermediate layer; 61. Transition film layer; 7. Black cover film. Detailed Implementation

[0050] The following is in conjunction with the instruction manual. Figure 1-9 This application will be described in further detail below.

[0051] Example 1: An FPC insulation structure with sheet-like jumpers, referring to... Figure 1 and Figure 2 The FPC body 1 includes a flexible substrate 11, on which conductive lines 12 are integrated, and a number of sheet-like jumpers 13 are provided on one side of the flexible substrate 11.

[0052] Reference Figure 2 and Figure 3 The conductive line 12 is provided with a plurality of bridging start points 121 and a plurality of bridging end points 122. The bridging start points 121, the sheet jumpers 13 and the bridging end points 122 are provided in a one-to-one correspondence, and one end of the sheet jumper 13 is connected to the corresponding bridging start point 121 and the other end is connected to the corresponding bridging end point 122.

[0053] In the design of the FPC body 1, the flexible substrate 11 is made of polyimide substrate, the conductive line 12 is made of copper foil line, and the sheet jumper 13 is a conductive silver sheet formed by silver paste printing and curing. Based on the arrangement of the sheet jumper 13 bridging between the bridging start point 121 and the bridging end point 122, a conductive connection can be formed across the original insulation area on the surface of the flexible substrate 11, thereby meeting the requirements of compact wiring and cross wiring in FPC.

[0054] Reference Figure 3 and Figure 4 The FPC insulation structure also includes several local insulating films 2, which are deposited on the flexible substrate 11. The local insulating films 2 are arranged in a one-to-one correspondence with the sheet jumpers 13, and the local insulating films 2 cover the corresponding bridging start point 121, sheet jumpers 13 and bridging end point 122.

[0055] Furthermore, the partial insulating film 2 is circular or square, and the edge of the partial insulating film 2 is fixedly connected to the flexible substrate 11. The middle part of the partial insulating film 2 is deposited and fixed on the surface of the corresponding bridging start point 121, the sheet jumper 13 and the bridging end point 122, and the remaining part is deposited and fixed on the surface of the flexible substrate 11.

[0056] Under the coverage of the local insulating film 2, the connection position between the sheet jumper 13, the bridging start point 121 and the bridging end point 122 can be insulated, thereby improving the local insulation reliability of the surface of the sheet jumper 13 and its connection with the flexible substrate 11.

[0057] In this embodiment, refer to Figure 3 The local insulating film 2 completely covers the corresponding sheet jumper 13, and the edge of the sheet jumper 13 is 2 mm away from the edge of the corresponding local insulating film 2.

[0058] In this embodiment, refer to Figure 3 The local insulating coating 2 is an inorganic insulating film formed by atomic layer deposition (ALD) or chemical vapor deposition (CVD). The inorganic insulating film is preferably made of one or more of the following materials: alumina, silicon dioxide, and silicon nitride, and its thickness is 20 nm to 200 nm.

[0059] Since atomic layer deposition or chemical vapor deposition are both vapor deposition film formation methods, unlike spraying, dispensing and other methods that mainly rely on the flow and spreading of liquid materials, vapor precursors can reach the side area, edge corner area and step transition area of ​​the sheet jumper 13 and its connection with the flexible substrate 11, and undergo deposition reaction on the corresponding surface to form an insulating film.

[0060] When forming the local insulating coating 2 using atomic layer deposition or chemical vapor deposition, the local insulating coating 2 can be directly deposited on the exposed surfaces of the patch jumper 13, the bridging start point 121, the bridging end point 122, and the flexible substrate 11. For metallic conductive surfaces, the local insulating coating 2 can achieve adhesion through interfacial chemical bonding formed by the deposition reaction, surface polarity effects, or micro-roughness intercalation; for the surface of the flexible substrate 11, the local insulating coating 2 can be fixed through interfacial bonding between the active groups generated after surface activation and the deposited film layer. Thus, a stable adhesion relationship can be formed between the local insulating coating 2 and the patch jumper 13, the bridging start point 121, the bridging end point 122, and the flexible substrate 11.

[0061] Based on this film formation method, the partial insulating coating 2 can form a relatively continuous covering on the upper surface, side edges and step transition area of ​​the sheet jumper 13 and its connection with the flexible substrate 11, thereby reducing dead corners and improving the integrity of the coverage of the sheet jumper 13.

[0062] Reference Figure 1 and Figure 4 The FPC insulation structure also includes an integral insulation coating 3, which is sprayed onto the flexible substrate 11 and covers the flexible substrate 11. A partial insulation film 2 is located between the integral insulation coating 3 and the flexible substrate 11 and is fixedly connected to the integral insulation coating 3.

[0063] Furthermore, the shape of the overall insulating coating 3 is adapted to the shape of the flexible substrate 11 so that the overall insulating coating 3 can completely cover the entire flexible substrate 11. On the overall insulating coating 3, in the area corresponding to the sheet jumper 13, the overall insulating coating 3 is fixedly connected to the corresponding local insulating film 2; in other areas, the overall insulating coating 3 is fixedly attached to the flexible substrate 11.

[0064] With the overall insulating coating 3 design, a continuous insulating protective layer can be formed on the surface of the flexible substrate 11, thereby encapsulating and protecting the local insulating film 2 and other areas on the flexible substrate 11, thus reducing the risk of external moisture, dust and ions penetrating the local insulating film 2 from the exposed areas on the flexible substrate 11.

[0065] In this embodiment, refer to Figure 1The overall insulating coating 3 completely covers the entire flexible substrate 11, but several through windows 31 are opened on the overall insulating coating 3. The contacts on the FPC body 1 used to connect to external circuits or other devices that do not need to be covered by insulation are located in the corresponding through windows 31.

[0066] In this embodiment, refer to Figure 1 The overall insulating coating 3 is an organic insulating resin layer formed by spraying or dipping. The organic insulating resin layer is made of one or more materials selected from polyimide resin, modified epoxy resin, polyurethane insulating resin, and acrylic insulating resin, and its thickness is 5μm to 50μm.

[0067] The integral insulating coating 3 formed by organic insulating resin can form a continuous mechanical protective layer and an environmental barrier layer on the outside of the partial insulating film 2, thereby improving the damp heat resistance, voltage resistance and bending resistance of the FPC insulation structure.

[0068] The implementation principle of this application embodiment is as follows: On the FPC body 1, the sheet jumper 13 is usually higher than the surface of the surrounding flexible substrate 11. This makes it easy to form a stepped transition area at the side edge of the sheet jumper 13 and the connection point with the bridging start point 121 and the bridging end point 122. Under conventional insulation covering process, the stepped transition area is prone to incomplete edge coverage and becomes the preferred location for leakage, short circuit or insulation failure in humid and hot environment, live environment or repeated bending environment.

[0069] To address this, this embodiment first uses a local insulating film 2 to specifically cover the area of ​​the patch jumper 13, and then uses an overall insulating coating 3 to cover the entire flexible substrate 11. This forms a continuous insulating protective layer on the surface of the FPC body 1, further reinforcing the protection of the local insulating film 2. Thus, the combination of the local insulating film 2 and the overall insulating coating 3 improves the insulation integrity and environmental protection capability of the FPC body 1 in the area of ​​the patch jumper 13, thereby enhancing the insulation reliability of the FPC insulation structure under conditions of high temperature, high humidity, repeated bending, and live operation.

[0070] This embodiment also provides a method for preparing an FPC insulation structure with sheet-like jumpers, including the following steps: S1. Obtain FPC body 1 and preprocess FPC body 1.

[0071] Specifically, step S1 includes the following steps: S11. Obtain the complete FPC ontology 1 described above.

[0072] S12. Perform dust removal, decontamination and residual volatile treatment on the surface of FPC body 1.

[0073] Specifically, one or more of the following methods can be used to clean the surface of the FPC body 1: dust-free airflow blowing, ultrasonic-assisted cleaning, isopropyl alcohol wiping, or vacuum adsorption dust removal, in order to remove dust, oil, and particulate impurities from the surface of the flexible substrate 11, the surface of the sheet jumper 13, and the areas near the bridging start point 121 and the bridging end point 122, thereby improving the cleanliness of the FPC body 1 surface.

[0074] S13. Dry and dehumidify the surface of the FPC body 1.

[0075] Specifically, the drying and dehumidification method is as follows: place the FPC body 1 in a drying oven and dry the FPC body 1 at a temperature of 60℃ to 120℃ for 50 to 60 minutes.

[0076] After this step is completed, the adsorbed moisture and residual volatile organic compounds on the surface of the flexible substrate 11 and the sheet jumper 13 can be removed.

[0077] S14. Perform surface activation treatment on the surface of FPC body 1.

[0078] Specifically, the surface activation treatment employs one or more of the following methods: plasma cleaning, ultraviolet ozone treatment, or corona treatment. After surface activation treatment, the surface energy of the sheet jumper 13 and the flexible substrate 11 can be increased, thereby further enhancing the adhesion of the local insulating film 2 and the overall insulating coating 3 to the surface of the FPC body 1.

[0079] S2. A local insulating film 2 is formed in the corresponding area of ​​each sheet jumper 13 on the FPC body 1, and the local insulating film 2 covers the corresponding bridging start point 121, sheet jumper 13 and bridging end point 122.

[0080] Specifically, step S2 includes the following steps: S21. Set up a deposition area on the FPC body 1.

[0081] Specifically, the locations of all sheet jumpers 13 on the FPC body 1 are set as deposition areas, and the corresponding bridging start point 121, sheet jumper 13 and bridging end point 122 are completely within the corresponding deposition areas.

[0082] S22. Deposit a local insulating coating 2 in all deposition areas on the FPC body 1.

[0083] Specifically, the local insulating coating 2 is deposited using either atomic layer deposition (ALD) or chemical vapor deposition (CVD). When using ALD, trimethylaluminum, water vapor, ozone, silicon source precursors, ammonia, etc., can be selected as reaction precursors; when using CVD, silane, ammonia, oxygen, etc., can be selected as gaseous precursors.

[0084] Since atomic layer deposition or chemical vapor deposition are both vapor deposition methods, the vapor precursor can reach the exposed surface of the sheet jumper 13 and the step transition area where it connects with the flexible substrate 11, and undergo a deposition reaction on the corresponding surface to form an insulating film. This allows the local insulating coating 2 to wrap the corresponding sheet jumper 13 to the maximum extent, thereby improving the insulation protection performance of the local insulating coating 2 for the sheet jumper 13.

[0085] S23, Local insulation coating 2 Film formation quality inspection.

[0086] Specifically, quality inspection can be carried out using one or more of the following methods: microscopic observation, film thickness testing, surface resistivity testing, and insulation withstand voltage sampling. The purpose is to identify whether there are any issues such as missing layers, pinholes, or insufficient local deposition in the local insulation coating 2.

[0087] S3. An integral insulating coating 3 is formed on the FPC body 1, so that the integral insulating coating 3 covers the surface of the FPC body 1, and the partial insulating film 2 is located between the integral insulating coating 3 and the flexible substrate 11.

[0088] Specifically, step S3 includes the following steps: S31, Overall Insulation Coating 3 Material Configuration.

[0089] Specifically, based on insulation requirements, flexibility requirements, and resistance to damp heat requirements, one or more of polyimide resin, modified epoxy resin, polyurethane insulating resin, or acrylic insulating resin are selected for preparation; then, appropriate amounts of corresponding types of diluents, leveling agents, adhesion promoters, and defoamers are added according to the coating method of the overall insulating coating 3. This forms the overall insulating coating 3 material that meets all performance requirements.

[0090] S32. Apply an integral insulating coating 3 to the FPC body 1.

[0091] Specifically, the overall insulating coating 3 is applied by spraying or dipping. When spraying, a spray gun or automatic spraying equipment can be used to uniformly spray the entire surface of the FPC body 1; when dipping, the entire FPC body 1 can be immersed in organic insulating resin material, then pulled up and the liquid controlled to form a continuous coating on its surface.

[0092] S33. A window 31 is formed on the overall insulating coating 3.

[0093] Specifically, the window 31 can be formed by pre-reserving a mask, selectively spraying to avoid it, laser opening, mechanical punching, or subsequent removal of local coatings.

[0094] S4. Cure the partial insulating film 2 and the overall insulating coating 3.

[0095] Specifically, step S4 includes the following steps: S41. Pre-bake the FPC body 1.

[0096] Specifically, the pre-baking process involves placing the FPC body 1 in a drying oven and drying it at 50°C to 100°C for 20 to 30 minutes to remove the solvent from the overall insulating coating 3 and stabilize its surface condition. This avoids problems such as bubbles, pinholes, or uneven thickness in the overall insulating coating 3 due to excessively rapid solvent evaporation during the subsequent formal curing process.

[0097] S42. Curing process is performed on the FPC body 1.

[0098] Specifically, the curing method is selected based on the material of the overall insulating coating 3. When the overall insulating coating 3 uses a thermosetting resin, it can be dried and cured at 80°C to 180°C. When the overall insulating coating 3 uses a photocurable resin, it can be cured by UV irradiation. Furthermore, photocuring and drying curing can be performed simultaneously or sequentially to ensure that the overall insulating coating 3 can be cured.

[0099] Following step S4, an optional final product inspection step may be performed. This inspection may include at least visual inspection, adhesion inspection, and insulation inspection. This step is designed to ensure that the final FPC insulation structure simultaneously meets the requirements for structural integrity, electrical insulation performance, and reliability.

[0100] The implementation principle of this application embodiment is as follows: First, the FPC body 1 is subjected to dust removal, decontamination, drying and dehumidification, and surface activation treatment to improve the bonding foundation between the subsequent local insulating film 2 and the overall insulating coating 3 and the FPC body 1; then, a local insulating film 2 is formed in the corresponding area of ​​the sheet jumper 13 by atomic layer deposition or chemical vapor deposition, and the local insulating film 2 wraps and covers the sheet jumper 13, thereby improving the local insulation protection capability of the sheet jumper 13; then, an overall insulating coating 3 is formed on the surface of the FPC body 1 by spraying or dip coating, so that the overall insulating coating 3 covers the entire surface of the FPC body 1, and at the same time covers the local insulating film 2, thereby forming a continuous insulating encapsulation; finally, the local insulating film 2, the overall insulating coating 3, and the relevant interface connection layer are cured to form a stable bond with the FPC body 1, thereby forming the final product.

[0101] Based on the above process, the local insulating film 2 can assume the local insulation function of the corresponding sheet jumper 13 area, and the overall insulating coating 3 can assume the overall insulation protection function. The combination of the two can improve the insulation weakness of the edge of the sheet jumper 13 and the connection position with the flexible substrate 11, thereby improving the insulation reliability of the FPC insulation structure under high temperature, high humidity, repeated bending and live operation conditions.

[0102] Example 2: An FPC insulation structure with sheet-like jumpers, referring to... Figure 5 and Figure 6 The difference between this embodiment and embodiment 1 is that a dense insulating film 4 is fixed on the surface of the sheet jumper 13, and the dense insulating film 4 wraps the corresponding sheet jumper 13.

[0103] Reference Figure 5 and Figure 6 The dense insulating film 4 has exposed windows 41 at both ends of the corresponding sheet jumper 13.

[0104] Reference Figure 4 and Figure 5 The exposed window 41 is located on the side of the corresponding sheet jumper 13 facing the flexible substrate 11, and the bridging start point 121 and the bridging end point 122 are respectively welded to the sheet jumper 13 through the corresponding exposed window 41.

[0105] Reference Figure 5 and Figure 6 A binder layer 5 is fixed on the surface of the dense insulating film 4.

[0106] Reference Figure 4 and Figure 6 When the local insulating film 2 is attached to the corresponding sheet jumper 13, the local insulating film 2 is fixedly connected to the corresponding adhesive layer 5.

[0107] Reference Figure 5 and Figure 6 In the surface structure design of the sheet jumper 13, the dense insulating film 4 serves as a layer structure fixed on the surface of the sheet jumper 13. On the one hand, it can provide pre-insulation protection for the sheet jumper 13 before use; on the other hand, after the sheet jumper 13 is assembled with the FPC body 1 and put into use, the dense insulating film 4 can continuously ensure the insulation performance of the surface of the sheet jumper 13, thereby improving the overall insulation reliability of the area of ​​the sheet jumper 13 in conjunction with the corresponding local insulating coating 2.

[0108] Meanwhile, by retaining exposed windows 41 at both ends of the sheet jumper 13, the welding connection between the sheet jumper 13 and the bridging start point 121 and the bridging end point 122 can be guaranteed to be unaffected, thus taking into account both the insulation protection requirements and the conductive connection requirements of the sheet jumper 13.

[0109] Furthermore, the binder layer 5 can form an interface bonding layer between the dense insulating film 4 and the partial insulating coating 2, thereby improving the adhesion, spreadability and bonding tightness of the partial insulating coating 2 on the corresponding sheet jumper 13, and thus reducing the risk of local curling, peeling or insufficient adhesion of the partial insulating coating 2 in subsequent bending, hot and cold cycling or humid and hot environments.

[0110] In this embodiment, refer to Figure 5 and Figure 6 A dense insulating film 4 covers all the outer surfaces of the sheet jumper 13, with exposed windows 41 only at both ends of the sheet jumper 13 to facilitate electrical connection. This gives the sheet jumper 13 good surface insulation protection before soldering and reduces the risk of the sheet jumper 13 surface being affected by external moisture, dust and corrosive media during storage, transportation, assembly and use.

[0111] In this embodiment, refer to Figure 6 The dense insulating film 4 is formed from an inorganic insulating film, a composite insulating film, or a highly dense insulating coating. Specifically, it can be made from one or more materials selected from alumina, silicon dioxide, silicon nitride, and ceramic filler-modified insulating resin, with a thickness of 20 nm to 5 μm, preferably 50 nm to 2 μm.

[0112] Based on the material selection of the dense insulating film 4, the dense insulating film 4 has good insulation performance, dense barrier performance and adhesion stability to the surface of the sheet jumper 13, thereby improving the surface of the sheet jumper 13's resistance to damp heat, anti-oxidation performance and insulation protection capability.

[0113] In this embodiment, refer to Figure 6 The binder layer 5 is formed by one or more of the following: an adhesion promoter layer, a coupling agent layer, a primer resin layer, or an adhesive modification layer. Specifically, it can be formed by one or more of the following materials: a silane coupling agent, a titanate coupling agent, a modified epoxy primer layer, or a polyurethane primer layer, with a thickness of 5 nm to 5 μm, preferably 20 nm to 1 μm.

[0114] Based on the material selection of the binder layer 5, the interfacial activity of the outer surface of the dense insulating film 4 can be improved, thereby improving the adhesion uniformity and bonding continuity of the local insulating coating 2 on the corresponding sheet jumper 13, and thus improving the connection stability between the local insulating coating 2 and the corresponding sheet jumper 13.

[0115] The implementation principle of this application embodiment is as follows: a dense insulating film 4 is formed on the outer surface of the sheet jumper 13, so that the sheet jumper 13 has basic insulation protection and barrier capabilities before assembly, which can reduce the risk of the sheet jumper 13 getting damp, oxidized or contaminated during storage, transportation and assembly.

[0116] Meanwhile, exposed windows 41 are retained at both ends of the sheet jumper 13, so that while the sheet jumper 13 is wrapped with the main body insulation, it can still achieve a stable conductive connection with the bridging start point 121 and the bridging end point 122 through the exposed windows 41.

[0117] The bonding agent layer 5 is provided on the outer surface of the dense insulating film 4, which can improve the adhesion and bonding tightness of the local insulating film 2 to the area of ​​the sheet jumper 13, thereby reducing the risk of local edge curling, peeling or insufficient adhesion of the local insulating film 2 in bending, hot and cold cycles and humid environments.

[0118] Therefore, by combining the dense insulating film 4 with the binder layer 5, the insulation reliability of the sheet jumper 13 can be improved, thereby further improving the long-term stability of the FPC with sheet jumper 13 under high temperature, high humidity, live operation and repeated bending conditions.

[0119] This embodiment also discloses a method for preparing an FPC insulation structure with sheet-like jumpers. The difference between this embodiment and Embodiment 1 is that: In step S1, step S11 specifically includes the following steps: S111, A dense insulating film 4 is formed on the surface of the sheet jumper 13.

[0120] Specifically, step S111 includes the following steps: S1111, Obtain the sheet jumper 13.

[0121] Specifically, the substrate of the sheet jumper 13 can be formed by printing and curing a conductive silver sheet with silver paste, or by forming a copper sheet, a silver-plated copper sheet, or a conductive metal sheet.

[0122] S1112. Clean and activate the surface of the sheet jumper 13.

[0123] Specifically, the cleaning and activation treatment can be carried out by one or more of the following methods: dust-free airflow purging, isopropanol cleaning, plasma cleaning, and ultraviolet ozone treatment. This can remove dust, oil, and residual organic matter from the surface of the sheet jumper 13, thereby improving the adhesion stability and film uniformity of the subsequent dense insulating film 4 on the surface of the sheet jumper 13.

[0124] S1113, A dense insulating film 4 is covered on the surface of the sheet jumper 13.

[0125] Specifically, the dense insulating film 4 can be formed by atomic layer deposition or chemical vapor deposition, and its film thickness is 20 nm to 5 μm. After this step is completed, an insulating protective layer can be pre-formed on the surface of the sheet jumper 13, so that the sheet jumper 13 has basic insulation and barrier capabilities before being assembled with the FPC body 1.

[0126] S1114. At both ends of the sheet jumper 13, the corresponding dense insulating film 4 is removed to form an exposed window 41.

[0127] Specifically, the exposed window 41 can be formed using one or more of the following methods: mask pre-reservation, selective film removal, laser removal, plasma etching, or mechanical removal. This ensures that the main body of the sheet jumper 13 is wrapped with a dense insulating film 4 while retaining conductive exposed areas at both ends of the sheet jumper 13 for welding connections.

[0128] S112. An adhesive layer 5 is formed on the outer surface of the dense insulating film 4.

[0129] Specifically, step S112 includes the following steps: S1121. Perform interface treatment on the surface of the dense insulating film 4.

[0130] Specifically, the interface treatment can be carried out by plasma activation, ultraviolet ozone treatment or surface cleaning treatment to improve the surface energy of the outer surface of the dense insulating film 4, thereby improving the adhesion of the subsequent binder layer 5 to the dense insulating film 4.

[0131] S1122. An adhesive layer 5 is formed on the outer surface of the dense insulating film 4.

[0132] Specifically, the binder layer 5 can be formed by one or more of the following methods: spraying, dipping, scraping, vapor deposition, chemical grafting, or printing. The binder layer 5 continuously covers the outer surface of the dense insulating film 4 and can extend to cover the edge area of ​​the exposed window 41, but does not obscure the exposed window 41.

[0133] S113. Fix the sheet jumper 13 to the FPC body 1 to obtain the complete FPC body 1.

[0134] Specifically, the method for fixing the sheet jumper 13 is as follows: the sheet jumper 13 is placed between the bridging start point 121 and the bridging end point 122 on the surface of the flexible substrate 11, so that the exposed windows 41 at both ends of the sheet jumper 13 are aligned with the corresponding bridging start point 121 and bridging end point 122 respectively; then, one of the following methods is used: welding, hot pressing, conductive adhesive connection, or reflow curing connection, so that the sheet jumper 13 is electrically connected to the bridging start point 121 and the bridging end point 122 through the corresponding exposed windows 41, thereby obtaining the complete FPC body 1.

[0135] The implementation principle of this application embodiment is as follows: Before fixing the sheet jumper 13 to the FPC body 1, the sheet jumper 13 is pre-treated, and a dense insulating film 4 is formed on the surface of the sheet jumper 13. Then, exposed windows 41 are formed at both ends of the sheet jumper 13, so that the sheet jumper 13 itself has basic insulation and surface barrier capabilities. Afterwards, an adhesive layer 5 is formed on the outer surface of the dense insulating film 4, thereby improving the adhesion and bonding continuity of the sheet jumper 13 to the local insulating coating 2, which facilitates the subsequent deposition of the local insulating coating 2.

[0136] Based on the above process, the sheet jumper 13 itself has insulation capabilities, and it is also easier to deposit and attach the local insulation coating 2. Thus, after the final preparation of the FPC insulation structure is completed, the insulation integrity, interlayer connection stability and long-term environmental adaptability of the sheet jumper 13 region can be improved.

[0137] Example 3: An FPC insulation structure with sheet-like jumpers, referring to... Figure 7 The difference between this embodiment and embodiment 1 is that an intermediate layer 6 is provided between the partial insulating film 2 and the overall insulating coating 3. The elastic modulus of the intermediate layer 6 is located between the elastic modulus of the partial insulating film 2 and the elastic modulus of the overall insulating coating 3, and the elastic modulus of the partial insulating film 2, the intermediate layer 6 and the overall insulating coating 3 decrease sequentially.

[0138] Reference Figure 7 Specifically, the intermediate layer 6 includes several transition film layers 61, which are stacked sequentially and fixedly connected. The stacking direction of the several transition film layers 61 is along the interval direction of the local insulating film 2 and the overall insulating coating 3, and the local insulating film 2 and the overall insulating coating 3 are respectively fixedly connected to the corresponding adjacent transition film layers 61.

[0139] Along the stacking direction of the several transition film layers 61, the elastic modulus of the local insulating film 2, the several transition film layers 61 and the overall insulating coating 3 decreases sequentially.

[0140] Because the elastic modulus of the partial insulating film 2 is greater than that of the overall insulating coating 3, if the partial insulating film 2 and the overall insulating coating 3 are directly connected, stress concentration is likely to occur at the interface between the partial insulating film 2 and the overall insulating coating 3 during bending, thermal cycling, or long-term use of the FPC body 1 due to the significant difference in rigidity and flexibility. In this case, the design of the intermediate layer 6 creates an intermediate transition region with a gradually changing elastic modulus between the partial insulating film 2 and the overall insulating coating 3. This allows for the gradual release of deformation stress caused by the difference in material rigidity and flexibility when the FPC body 1 is bent, thereby reducing the risk of interface peeling, local cracking, or insulation failure between the partial insulating film 2 and the overall insulating coating 3.

[0141] In this embodiment, refer to Figure 7 The number of transition membrane layers 61 is 2 to 5.

[0142] In this embodiment, refer to Figure 7 The transition film layer 61 is formed by one or more of the following materials: organic-inorganic hybrid insulating material, nanofiller modified insulating resin, silicone modified polyurethane resin, acrylic modified insulating resin, and modified epoxy resin.

[0143] Since the elastic modulus of the transition film layer 61 is related to the content of inorganic phase inside the film layer, the flexibility of organic resin and the density of cross-linking network, different elastic moduli can be formed in each transition film layer 61 by changing the ratio of inorganic filler to resin component in different transition film layers 61, or by changing the curing degree and cross-linking density of different transition film layers 61.

[0144] Therefore, when several transition film layers 61 are stacked and fixed in sequence, an intermediate layer 6 with a gradually changing elastic modulus can be constructed, which can reduce the sudden change in modulus when the local insulating film 2 and the overall insulating coating 3 are in direct contact.

[0145] The implementation principle of this application embodiment is as follows: an intermediate layer 6 composed of several transition film layers 61 is provided between the local insulating film 2 and the overall insulating coating 3, so that the local insulating film 2 and the overall insulating coating 3 are no longer in direct contact with large differences in rigidity, but form a transitional connection relationship with gradually changing elastic modulus.

[0146] Therefore, when the FPC body 1 deforms during bending, thermal cycling, or long-term use, the interfacial stress between the local insulating film 2 and the overall insulating coating 3 due to the difference in material rigidity and flexibility can be released and buffered layer by layer in the intermediate layer 6, thereby reducing the sudden change in interlayer modulus and reducing the risk of interface peeling, local cracking, or insulation failure.

[0147] This embodiment also discloses a method for preparing an FPC insulation structure with sheet-like jumpers. The difference between this embodiment and Embodiment 1 is that: The following steps are also included between step S3 and step S4: S100, An intermediate layer 6 is formed on the local insulating film 2, and the intermediate layer 6 covers the corresponding local insulating film 2.

[0148] Specifically, step S100 includes the following steps: S1001, Configure several transition film layers 61 material.

[0149] Specifically, based on the difference in elastic modulus between the partial insulating film 2 and the overall insulating coating 3, transition film layer 61 materials with different elastic moduli are respectively configured; The transition film layer 61 material can be formed by one or more of the following: organic-inorganic hybrid insulating materials, nanofiller modified insulating resins, silicone modified polyurethane resins, acrylic modified insulating resins, and modified epoxy resins.

[0150] By changing the ratio of inorganic fillers to resin components in different transition membrane layers 61, or by changing the degree of curing and crosslinking density of different transition membrane layers 61, different elastic moduli can be formed in each transition membrane layer 61.

[0151] S1002, Several transition film layers 61 are sequentially covered on the outside of the local insulating film 2.

[0152] Specifically, the transition film 61 can be formed by one or more of the following methods: spraying, scraping, printing, slot coating, or spin coating.

[0153] S1003. Several transition film layers 61 are pre-cured in sequence to form an intermediate layer 6.

[0154] Specifically, after each transition film layer 61 is formed, the corresponding transition film layer 61 can be pre-cured by one of the following methods: low-temperature pre-baking, short-time heat treatment, or UV pre-curing.

[0155] The implementation principle of this application embodiment is as follows: After the local insulating film 2 is formed and before the overall insulating coating 3 is formed, a number of transition film layers 61 are sequentially deposited on the outside of the local insulating film 2 to form an intermediate layer 6. Since the elastic modulus of each transition film layer 61 is between that of the local insulating film 2 and the overall insulating coating 3, an intermediate transition region with a gradually changing elastic modulus can be constructed between the local insulating film 2 and the overall insulating coating 3 after the subsequent formation of the overall insulating coating 3.

[0156] Example 4: An FPC insulation structure with sheet-like jumpers, referring to... Figure 8 The difference between this embodiment and embodiment 1 is that the overall insulating coating 3 includes a main flexible film 32 and several reinforcing cover films 33. The main flexible film 32 and several reinforcing cover films 33 are coated on the flexible substrate 11. The thickness of the reinforcing cover film 33 is greater than the thickness of the main flexible film 32, and the main flexible film 32 and several reinforcing cover films 33 are integrally formed.

[0157] Reference Figure 8 The reinforcing cover film 33 is provided in a one-to-one correspondence with the local insulating cover film 2, and the reinforcing cover film 33 covers the corresponding local insulating cover film 2, and the reinforcing cover film 33 completely covers the corresponding local insulating cover film 2.

[0158] Under the structural design of the overall insulating coating 3, the main flexible film 32 can cover all areas of the flexible substrate 11 except for the area of ​​the sheet jumper 13, thereby ensuring continuous insulating coverage of the entire surface of the FPC body 1. The reinforcing cover film 33 covers the area of ​​the sheet jumper 13 and forms a local thickening protection at the location of the local insulating film 2, thereby improving the insulation thickness, environmental barrier capability, and resistance to mechanical damage of the area of ​​the sheet jumper 13. Thus, the overall insulating coating 3 can take into account both the overall board flexibility requirements and the key reinforcement requirements of the area of ​​the sheet jumper 13.

[0159] In this embodiment, refer to Figure 8 The main flexible film 32 and the reinforcing cover film 33 can be formed using the same material system. The reinforcing cover film 33 increases the film thickness in corresponding areas by local touch-up coating, selective spraying, local printing coating, or local dot coating. The reinforcing cover film 33 is formed before the main flexible film 32 is fully cured, or it is applied again to the corresponding areas after the main flexible film 32 is formed, and after uniform curing, a continuous film transition structure is formed between the main flexible film 32 and the reinforcing cover film 33. Therefore, the main flexible film 32 and the reinforcing cover film 33 can be regarded as an integral structure after molding, but they have different film thicknesses in different areas.

[0160] Specifically, both the main flexible membrane 32 and the reinforcing cover membrane 33 can be made of one or more of the following materials: polyimide resin, modified epoxy resin, polyurethane insulating resin, and acrylic insulating resin.

[0161] The thickness of the reinforcing cover film 33 is 1.2 to 4 times the thickness of the main flexible film 32.

[0162] The implementation principle of this application embodiment is as follows: the overall insulating coating 3 adopts a partitioned thickening structure that combines the main flexible film 32 and the reinforcing cover film 33. The main flexible film 32 mainly covers the conventional area on the flexible substrate 11 to ensure that the FPC body 1 still has good flexibility. The reinforcing cover film 33 mainly covers the area corresponding to the sheet jumper 13 to form local thickening protection at the location of the local insulating film 2.

[0163] Since the area of ​​the patch jumper 13 typically has issues such as edge corners, stepped transitions, and localized stress concentrations, a reinforcing cover film 33 can be applied to this area to improve the insulation thickness, environmental barrier properties, and resistance to mechanical damage. Therefore, the overall insulating coating 3 can meet both the overall board flexibility requirements and the key reinforcement needs of the patch jumper 13 area, thereby further improving the overall reliability of the FPC body 1.

[0164] This embodiment also discloses a method for preparing an FPC insulation structure with sheet-like jumpers. The difference between this embodiment and Embodiment 1 is that: In step S3, step S32 specifically includes the following steps: S321. A main flexible film 32 is formed on the surface of the FPC body 1.

[0165] Specifically, the integral insulating coating 3 material is formed on the surface of the FPC body 1 by one or more methods, such as spraying, dip coating, slot coating, or roll coating, to obtain a base film layer that continuously covers the surface of the FPC body 1. The base film layer constitutes the main flexible film 32. The main flexible film 32 can cover the conventional area of ​​the flexible substrate 11 and cover the area where the partial insulating film 2 is located as a base layer for subsequent local thickening film formation.

[0166] S322, An reinforcing covering film 33 is formed in the corresponding local insulating covering film 2 area.

[0167] Specifically, after the main flexible film 32 is formed, an reinforcing cover film 33 is formed by superimposing one or more of the following methods on the corresponding area of ​​each local insulating film 2: local touch-up coating, selective spraying, local printing coating, local dot coating, or repeated coating. The reinforcing cover film 33 is set in a one-to-one correspondence with the local insulating film 2, and the reinforcing cover film 33 completely covers the corresponding local insulating film 2.

[0168] By using the above-mentioned local superposition coating method, the total thickness of the membrane layer in the area where the cover membrane 33 is located is greater than the thickness of the membrane layer in the area where the main flexible membrane 32 is located.

[0169] To form an integral structure between the main flexible film 32 and the reinforcing cover film 33, the reinforcing cover film 33 can be formed while the main flexible film 32 is not fully cured, allowing material mutual dissolution, chain segment entanglement, cross-linking, or adhesion to occur at the interface; alternatively, after the main flexible film 32 has initially formed, the reinforcing cover film 33 can be superimposed again in the corresponding area, and uniform curing can be used to form a continuous film layer between the main flexible film 32 and the reinforcing cover film 33. Thus, although the main flexible film 32 and the reinforcing cover film 33 have different thicknesses in different areas, they can still form an integral insulating coating 3 with a continuous interface after molding.

[0170] It should be noted that the integral molding of the main flexible membrane 32 and the reinforcing cover membrane 33 in this application means that the two form a continuous membrane structure after final curing, and there are no independently assembled prefabricated membrane sheets at the interface; it does not limit the main flexible membrane 32 and the reinforcing cover membrane 33 to be formed by a single uniform thickness coating. For those skilled in the art, an integrated membrane structure with a continuous interface can also be obtained by first forming a base membrane layer, then performing secondary superposition of membranes in local areas and uniform curing.

[0171] The implementation principle of this application embodiment is as follows: the formation method of the overall insulating coating 3 is improved, that is, a main flexible film 32 is first formed on the surface of the FPC body 1, and then a reinforcing cover film 33 is formed in the corresponding local insulating film 2 area, and the main flexible film 32 and the reinforcing cover film 33 are integrally formed. As a result, the overall insulating coating 3 can maintain good flexible coverage in ordinary areas, and can form local thickening protection in the area of ​​the sheet jumper 13.

[0172] Based on the above process, the insulation thickness, environmental barrier capability, and damage resistance of the sheet jumper 13 area can be improved without significantly affecting the overall board flexibility, thereby enhancing the overall insulation performance of the FPC insulation structure.

[0173] Example 5: An FPC insulation structure with sheet-like jumpers, referring to... Figure 9 The difference between this embodiment and embodiment 1 is that the FPC insulation structure also includes a black cover film 7, which is fixed on the side of the overall insulation coating 3 away from the flexible substrate 11, and the black cover film 7 completely covers the entire overall insulation coating 3.

[0174] Under this structural design, the black cover film 7 can form an outer re-encapsulation of the overall insulating coating 3, thereby further improving the surface integrity, anti-fouling performance, abrasion resistance and environmental barrier capability of the entire FPC insulation structure.

[0175] In this embodiment, refer to Figure 9 The black cover film 7 is formed of one or more materials selected from black polyimide protective film, black PET protective film, flexible insulating protective film containing black pigment, or black resin encapsulation layer, and its thickness is 3μm to 50μm, preferably 5μm to 30μm.

[0176] Based on the material selection of the black cover film 7, the black cover film 7 can combine appearance shielding, surface protection and flexible adaptability, thereby improving the external use stability and product consistency of the entire FPC insulation structure.

[0177] The implementation principle of this application embodiment is as follows: the black cover film 7 can not only provide additional wear resistance, anti-fouling and environmental barrier to the overall insulating coating 3, but also improve the appearance concealment and consistency of the product.

[0178] Meanwhile, the black cover film 7, as the outermost protective layer, can also reduce the direct erosion of the overall insulation coating 3 by external moisture, dust and corrosive media, thereby improving the surface integrity and external stability of the entire FPC insulation structure.

[0179] Therefore, by setting the black cover film 7, the long-term reliability of the FPC insulation structure in complex environments can be further improved.

[0180] This embodiment also discloses a method for preparing an FPC insulation structure with sheet-like jumpers. The difference between this embodiment and Embodiment 1 is that: The following steps are included after step S4: S200, A black cover film 7 is laminated onto the overall insulating coating 3.

[0181] Specifically, step S200 includes the following steps: S2001, Obtain the black covering film 7.

[0182] Specifically, the black cover film 7 may be formed from one or more of the following materials: black polyimide protective film, black PET protective film, flexible insulating protective film containing black pigment, or black resin encapsulation layer.

[0183] S2002. Fix the black cover film 7 to the overall insulating coating 3.

[0184] Specifically, when the black covering film 7 is a pre-made film material, it can be fixed to the outside of the overall insulating coating 3 by hot pressing, vacuum bonding, or roll bonding; when the black covering film 7 is a coating material, it can be formed by spraying, printing, scraping, or casting and then curing. Furthermore, the black covering film 7 completely covers the entire overall insulating coating 3.

[0185] The implementation principle of this application embodiment is as follows: after the overall insulating coating 3 is formed and cured, a black covering film 7 is then attached or formed on its outer side, so that the outer side of the entire FPC insulating structure is further encapsulated and protected.

[0186] Based on the above process, the black cover film 7 can build an outer protective interface outside the overall insulating coating 3, thereby further improving the wear resistance, anti-fouling performance and environmental barrier performance of the FPC insulation structure, and enhancing the product's appearance shielding effect and usage stability.

[0187] It should be noted that the dense insulating film 4 and binder layer 5 on the sheet jumper 13 disclosed in Example 2, the intermediate layer 6 disclosed in Example 3, the overall insulating coating 3 structure disclosed in Example 4, and the black covering film 7 disclosed in Example 5 can be set separately or arbitrarily combined according to actual usage requirements.

[0188] In other words, within the same FPC insulation structure, a dense insulating film 4, an adhesive layer 5, a local insulating coating 2, an intermediate layer 6, an overall insulating coating 3, and a black cover film 7 can coexist to form a multi-layered synergistic insulation protection structure. Through the coordination of these layers, the insulation integrity, interlayer connection stability, and environmental adaptability of the patch jumper 13 region can be improved from different aspects, such as insulation of the patch jumper 13, interlayer adhesion enhancement, modulus gradient transition, local thickening protection, and external re-encapsulation. This further enhances the long-term insulation reliability of the FPC insulation structure under conditions of high temperature, high humidity, energized operation, and repeated bending.

[0189] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. An FPC insulation structure with sheet-like jumpers, characterized in that, include: The FPC body (1) includes a flexible substrate (11) and a plurality of sheet jumpers (13). The flexible substrate (11) has integrated conductive lines (12). The conductive lines (12) are provided with a plurality of bridging start points (121) and a plurality of bridging end points (122). The sheet jumpers (13) are disposed on one side of the flexible substrate (11). The bridging start points (121), the sheet jumpers (13) and the bridging end points (122) are provided in a one-to-one correspondence. One end of the sheet jumper (13) is connected to the corresponding bridging start point (121) and the other end is connected to the corresponding bridging end point (122). Several partial insulating films (2) are formed on the flexible substrate (11) by vapor deposition. The partial insulating films (2) are arranged in a one-to-one correspondence with the sheet jumpers (13). The partial insulating films (2) cover the jumper starting point (121), the sheet jumper (13) and the jumper ending point (122). An integral insulating coating (3) is fixed and covers the flexible substrate (11), and a plurality of partial insulating films (2) are located between the integral insulating coating (3) and the flexible substrate (11), and the partial insulating films (2) are fixedly connected to the integral insulating coating (3).

2. The FPC insulation structure with sheet-like jumpers according to claim 1, characterized in that, A dense insulating film (4) is fixed on the outer surface of the sheet jumper (13), and the dense insulating film (4) wraps around the sheet jumper (13).

3. The FPC insulation structure with sheet-like jumpers according to claim 2, characterized in that, The dense insulating film (4) has exposed windows (41) at both ends of the corresponding sheet jumper (13), and the exposed windows (41) are located on the side of the corresponding sheet jumper (13) facing the flexible substrate (11).

4. The FPC insulation structure with sheet-like jumpers according to claim 2, characterized in that, A binder layer (5) is fixed to the outside of the dense insulating film (4), and the local insulating film (2) is fixedly connected to the corresponding binder layer (5).

5. The FPC insulation structure with sheet-like jumpers according to claim 1, characterized in that, An intermediate layer (6) is provided between the partial insulating film (2) and the overall insulating coating (3). The partial insulating film (2), the intermediate layer (6) and the overall insulating coating (3) are connected in sequence, and the elastic modulus of the partial insulating film (2), the intermediate layer (6) and the overall insulating coating (3) decreases in sequence.

6. The FPC insulation structure with sheet-like jumpers according to claim 5, characterized in that, The intermediate layer (6) includes a plurality of transition film layers (61), which are stacked and fixedly connected in sequence along the interval direction of the partial insulating film (2) and the overall insulating coating (3). The partial insulating film (2) and the overall insulating coating (3) are respectively fixedly connected to the corresponding adjacent transition film layers (61). Along the spacing direction between the partial insulating film (2) and the overall insulating coating (3), the elastic modulus of the partial insulating film (2), the plurality of transition film layers (61) and the overall insulating coating (3) decrease sequentially.

7. The FPC insulation structure with sheet-like jumpers according to claim 1, characterized in that, The side of the integral insulating coating (3) facing away from the flexible substrate (11) is covered with a black cover film (7), and the black cover film (7) is fixedly connected to the integral insulating coating (3).

8. The FPC insulation structure with sheet-like jumpers according to claim 1, characterized in that, The overall insulating coating (3) includes a main flexible film (32) and a plurality of reinforcing cover films (33). The main flexible film (32) and the plurality of reinforcing cover films (33) are both fixed on the flexible substrate (11). The plurality of reinforcing cover films (33) are all fixedly connected to the main flexible film (32), and the thickness of the reinforcing cover film (33) is greater than the thickness of the main flexible film (32). The reinforcing cover film (33) is provided in a one-to-one correspondence with the local insulating cover film (2), and the reinforcing cover film (33) covers the corresponding local insulating cover film (2), and the reinforcing cover film (33) is fixedly connected to the corresponding local insulating cover film (2).

9. An FPC insulation structure with sheet-like jumpers according to claim 8, characterized in that, Several of the aforementioned reinforcing cover films (33) are integrally formed with the main flexible film (32).

10. A method for preparing an FPC insulation structure with sheet-like jumpers, used to prepare an FPC insulation structure with sheet-like jumpers as described in any one of claims 1-9, characterized in that, Includes the following steps: Obtain the FPC body (1) and preprocess the FPC body (1); A local insulating film (2) is formed in the corresponding area of ​​each sheet jumper (13) on the FPC body (1), and the local insulating film (2) covers the corresponding bridging start point (121), the sheet jumper (13) and the bridging end point (122). An integral insulating coating (3) is formed on the FPC body (1) such that the integral insulating coating (3) covers the surface of the FPC body (1) and the partial insulating film (2) is located between the integral insulating coating (3) and the flexible substrate (11); The partial insulating film (2) and the overall insulating coating (3) are cured.

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