Flexible circuit board for addition process light-emitting device and manufacturing method of flexible circuit board
By using an additive process to set an interface bonding layer and conductive circuit patterns on flexible circuit boards, the problems of low material utilization and long production cycle are solved, and efficient and low-cost flexible circuit board manufacturing is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-23
- Publication Date
- 2026-04-10
Smart Images
Figure CN121842945A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of circuit board manufacturing, in particular to a flexible circuit board for light-emitting device using additive process and a manufacturing method thereof. BACKGROUND
[0002] In the field of flexible circuit board manufacturing, subtractive process centered on etching of copper-clad board has long dominated. This method first requires laminating whole copper foil on insulating substrate, and then removing the excess part through complex pattern transfer and chemical etching process to form circuit. This process route inevitably leads to the following problems: first, low material utilization, most of the copper foil is etched and removed as waste, not only directly increasing the cost of raw materials, but also generating a large amount of copper-containing waste liquid, increasing the burden and comprehensive cost of environmental protection treatment; second, the manufacturing process is long, involving dry film lamination, exposure, development, etching and film removal, etc. Multiple precise chemical processing steps, large equipment investment, complex process control and long production cycle. These factors jointly restrict the competitiveness of traditional subtractive method FPC in application scenarios pursuing lower cost, faster response and better material efficiency. SUMMARY
[0003] The technical problem to be solved by the present application is to provide a flexible circuit board for light-emitting device using additive process and a manufacturing method thereof. The technical scheme for solving the above technical problem is as follows: On the one hand, the present application provides a flexible circuit board for light-emitting device using additive process, comprising a flexible insulating substrate, an interfacial bonding layer arranged on the surface of the flexible insulating substrate, a conductive circuit pattern formed on the interfacial bonding layer, and a protective layer covering the non-connection area of the conductive circuit pattern. The material of the interfacial bonding layer is at least one of acrylic resin, epoxy resin, polyimide precursor or polyurethane.
[0004] The beneficial effects of the present application are: by setting a specific interfacial bonding layer, the core technical problem of poor adhesion when directly forming a conductive circuit on a smooth flexible insulating substrate is fundamentally solved, providing a reliable foundation for subsequent additive process, ensuring the mechanical stability and long-term reliability of the circuit.
[0005] On the basis of the above technical scheme, the present application can also be improved as follows.
[0006] Further, the conductive circuit pattern is formed by printing and sintering of conductive paste, the conductive paste includes conductive filler and resin binder, and the material of the conductive filler is at least one of silver powder, silver flake, copper powder and silver-copper alloy powder.
[0007] The beneficial effect of the above further scheme is that the conductive paste is drawn according to the conductive circuit pattern by using a printing device, and the use efficiency of the conductive paste is higher than that of etching a copper-clad plate to form a conductive circuit. Meanwhile, the conductive circuit is arranged on the interface bonding layer, so that the structural stability between the conductive circuit and the flexible insulating substrate can be effectively improved.
[0008] Further, the protective layer is an insulating ink layer or a cover film.
[0009] Further, the flexible insulating substrate is a polyimide film or a polyester film.
[0010] Further, at least one second interface bonding layer is arranged on the conductive circuit pattern, and a second conductive circuit pattern is formed on the second interface bonding layer, and the second conductive circuit pattern is electrically connected with the lower conductive circuit pattern through a conductive via.
[0011] The beneficial effect of the above further scheme is that the interface bonding layer and the conductive circuit pattern are arranged in a stacked manner, and the conductive circuits of different layers are electrically connected through the conductive via, so that the density of the circuit wiring can be improved without significantly increasing the overall thickness and hardness.
[0012] In another aspect, the present application further provides a manufacturing method of a flexible circuit board for a light-emitting device, comprising the following steps: S1: providing a flexible insulating substrate; S2: forming an interface bonding layer on at least one surface of the flexible insulating substrate; S3: printing a conductive paste on the interface bonding layer to form a conductive circuit pattern; S4: curing and sintering the printed conductive paste to form a dense conductive circuit; S5: forming a protective layer on the non-connected area of the conductive circuit pattern.
[0013] The beneficial effect of the present application is that, compared with the flexible circuit board manufacturing method based on etching a copper-clad plate, the manufacturing method reduces the multiple complex processes such as copper cladding, film pasting, exposure, development, etching, and film removing. Therefore, the process flow of the flexible circuit board is simplified, and the production cycle is shortened, so that the problem of waste of a large amount of copper material due to etching and the problem of chemical waste liquid treatment can be fundamentally avoided.
[0014] On the basis of the above technical scheme, the present application can be further improved as follows.
[0015] Further, in step S2, the interface bonding layer with a thickness of 2-50 μm is formed by gravure coating or slit coating process.
[0016] The beneficial effect of the above further solution is that by controlling the thickness of the interface bonding layer, the over-thickness of the substrate affecting the flexibility or increasing the material cost can be effectively avoided.
[0017] Further, in step S3, the conductive circuit pattern is formed by using a screen printing or inkjet printing process.
[0018] The beneficial effect of the above further solution is that by using the screen printing or inkjet printing process, high-precision and accurate printing of the conductive circuit pattern on the surface of the interface bonding layer can be realized to form the conductive circuit. Compared with the copper-clad plate etching-based flexible circuit board manufacturing method, the manufacturing method consumes less conductive paste, thereby improving the utilization rate of the material.
[0019] Further, the protective layer is formed by screen printing insulating ink and curing or by hot pressing a cover film.
[0020] Further, after step S5, there is further a step S6 of performing shape cutting on the flexible circuit board formed with the protective layer, the interface bonding layer and the flexible insulating substrate by using a die-cutting process.
[0021] The beneficial effect of the above further solution is that by using the die-cutting process to trim the excess part of the shape of the protective layer, the interface bonding layer and the flexible insulating substrate, the manufacturing of the flexible circuit board for the light-emitting device is completed. BRIEF DESCRIPTION OF DRAWINGS
[0022] The present application is further illustrated below in conjunction with the accompanying drawings and examples.
[0023] Figure 1 FIG. 1 is a structural schematic diagram of the flexible circuit board for the light-emitting device in the additive process of the present application; Figure 2 FIG. 2 is a flow chart of the manufacturing method of the flexible circuit board in the present application; Figure 3 FIG. 3 is a multi-layer structural schematic diagram of the flexible circuit board for the light-emitting device in the additive process of the present application.
[0024] In the drawings, the components represented by the respective reference numerals are listed as follows: 10, flexible insulating substrate; 20, interface bonding layer; 30, conductive circuit pattern; 40, protective layer. DETAILED DESCRIPTION
[0025] The concept, specific structure and generated technical effects of the present application will be described clearly and completely in combination with the embodiments and drawings, so as to fully understand the purpose, features and effects of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments, and other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative labor are within the protection scope of the present application. In addition, all the coupling / connection relationships involved in the patent do not mean that the components are directly connected, but that a better coupling structure can be composed by adding or reducing coupling accessories according to the specific implementation. The technical features in the present application can be combined interactively without conflict.
[0026] Embodiment one With reference to Figure 1 The present application provides a flexible circuit board for light emitting device in additive process, which comprises a flexible insulating substrate 10, an interface bonding layer 20 arranged on the surface of the flexible insulating substrate 10, a conductive circuit pattern 30 formed on the interface bonding layer 20, and a protective layer 40 covering the non-connecting area of the conductive circuit pattern 30; the material of the interface bonding layer 20 is at least one of acrylic resin, epoxy resin, polyimide precursor or polyurethane.
[0027] In the present embodiment, the flexible circuit board comprises a flexible insulating substrate 10, and an interface bonding layer 20, a conductive circuit pattern 30 and a protective layer 40 are sequentially formed from bottom to top on the upper end surface of the flexible insulating substrate 10. The thickness of the protective layer 40 is 5-50 μm, which is used to protect the conductive circuit formed by the conductive circuit pattern 30. The thickness of the interface bonding layer 20 is 5-50 μm, which is used to increase the adhesive bonding force between the conductive circuit pattern 30 and the flexible insulating substrate 10. In addition, the material of the interface bonding layer 20 can be any one of acrylic resin, epoxy resin, polyimide precursor or polyurethane, or a mixture of multiple materials.
[0028] By arranging a specific interface bonding layer 20 between the conductive circuit pattern 30 and the flexible insulating substrate 10, the core technical problem of poor adhesion when directly forming a conductive circuit on a smooth flexible insulating substrate 10 can be effectively solved, and the mechanical stability and long-term reliability of the circuit are ensured.
[0029] Preferably, with reference to Figure 1 The conductive circuit pattern 30 is formed by printing and sintering of conductive paste, the conductive paste comprises conductive filler and resin binder, and the material of the conductive filler is at least one of silver powder, silver flake, copper powder and silver-copper alloy powder.
[0030] In the embodiment, the conductive paste is liquid, which is mixed by conductive filler and resin adhesive. The material of the conductive filler can be silver powder, silver sheet, copper powder, silver-copper alloy powder or other conductive substances, and the conductive filler can be one of them or a mixture of multiple kinds. The conductive paste is printed on the interface bonding layer 20 according to the designed conductive circuit pattern 30 by a printing device, and then is dried by a sintering device, so as to complete the conductive circuit.
[0031] By using the printing device to draw the conductive paste according to the conductive circuit pattern 30, the use amount of the conductive paste is more efficient than that of etching the conductive circuit on the copper-clad plate. At the same time, by arranging the conductive circuit on the interface bonding layer 20, the structural stability between the conductive circuit and the flexible insulating substrate 10 can be effectively improved.
[0032] Preferably, referring to Figure 1 , the protective layer 40 is an insulating ink layer or a cover film.
[0033] In the embodiment, the protective layer 40 is arranged above the conductive circuit pattern 30, and is used for protecting the conductive circuit. Specifically, the protective layer 40 can be an insulating ink layer or a cover film, and the insulating ink can be white ink, black ink or green ink, and the cover film can be white adhesive film or black adhesive film.
[0034] In some embodiments, the protective layer 40 can be a specific white solder resist ink layer or cover film. By arranging the white protective layer 40, the light reflectivity of the light-emitting device can be effectively improved, so as to improve the light efficiency and uniformity.
[0035] Preferably, referring to Figure 1 , the flexible insulating substrate 10 is a polyimide film or a polyester film.
[0036] In the embodiment, the flexible insulating substrate is a support base of the flexible circuit board, and the thickness thereof can be 25-100 μm.
[0037] Preferably, referring to Figure 3 , at least one second interface bonding layer 20 is arranged on the conductive circuit pattern 30, and a second conductive circuit pattern 30 is formed on the second interface bonding layer 20, and the second conductive circuit pattern 30 is electrically connected with the lower conductive circuit pattern 30 through a conductive via.
[0038] In the embodiment, the upper end surface of the flexible insulating substrate 10 is sequentially formed from bottom to top with an interface bonding layer 20, a conductive circuit pattern 30, a second interface bonding layer 20, a second conductive circuit pattern 30, and a protective layer 40. The second conductive circuit pattern 30 forms a second conductive circuit electrically connected to the lower layer conductive circuit through a conductive via. Specifically, the conductive via is arranged vertically to the interface bonding layer 20.
[0039] The interface bonding layer 20 and the conductive circuit pattern 30 are arranged in a superposition manner, and the conductive circuits of different layers are electrically connected through the conductive via, so that the density of the circuit wiring is improved without significantly increasing the overall thickness and hardness.
[0040] Embodiment Two Reference Figure 2 On the basis of the embodiment one, the application further provides a manufacturing method of the flexible circuit board for the light-emitting device by additive process, comprising the following steps: S1: providing a flexible insulating substrate 10; In the embodiment, the flexible insulating substrate 10 can be a polyester film or a polyimide film, and the thickness thereof can be 25-100 μm of polyester film or polyimide film.
[0041] S2: forming an interface bonding layer 20 on at least one surface of the flexible insulating substrate 10; coating and drying In the embodiment, the interface bonding layer 20 is formed by coating any one or more of acrylic resin, epoxy resin, polyimide precursor, or polyurethane on the flexible insulating substrate 10 and curing at high temperature, and the lower surface thereof is fixedly bonded to the flexible insulating substrate 10, and the upper surface thereof forms a micro-rough surface for increasing the stability of the conductive circuit pattern 30.
[0042] S3: printing a conductive paste on the interface bonding layer 20 to form a conductive circuit pattern 30; printing and drying S4: curing and sintering the printed conductive paste to form a dense conductive circuit; In the embodiment, the conductive paste comprises a liquid paste mixed by conductive fillers and a resin adhesive, wherein the conductive fillers can be silver powder, silver sheet, copper powder, silver-copper alloy powder, or other conductive substances. The conductive paste is printed on the surface of the interface bonding layer 20 with a micro-rough surface according to the designed conductive circuit pattern 30, and the conductive circuit is formed by curing the conductive paste.
[0043] It should be explained that the resin adhesive used in the present example should have adhesion, flexibility and heat resistance, and should also be compatible with the conductive filler. Specifically, the resin adhesive can be epoxy resin, polyimide resin or acrylic resin. Thus, the conductive filler is adhered together by the resin adhesive, and the adhesion stability of the conductive paste and the interface bonding layer 20 is improved.
[0044] S5: forming a protective layer 40 on the non-connection area of the conductive circuit pattern 30.
[0045] In the present example, the liquid insulating ink layer or the cover film is precisely printed on the surface of the non-connection area of the conductive circuit pattern 30, and is cured at high temperature to form a protective layer 40 with a thickness of 5-50 μm. Specifically, the insulating ink can be white oil, black oil or green oil, and the cover film can be white oil adhesive film or black oil adhesive film.
[0046] By the manufacturing method, compared with the manufacturing method of flexible circuit board taking etching of copper-clad plate as the core, the complex processes such as copper cladding, film pasting, exposure, development, etching and film removing are reduced. Thus, the process flow of the flexible circuit board is simplified, and the production cycle is shortened, so that the problem of waste of a large amount of copper material due to etching and the problem of treatment of chemical waste liquid are fundamentally avoided.
[0047] Preferably, the interface bonding layer 20 with a thickness of 2-50 μm is formed by gravure coating or slot coating process.
[0048] In the present embodiment, the interface bonding layer 20 is formed on the flexible insulating substrate 10 by adopting a gravure coating or slot coating process. Specifically, in the gravure coating process, a metal roller engraved with fine micro-holes is rotated and immersed in a slurry tank formed by any one of acrylic resin, epoxy resin, polyimide precursor or polyurethane, the slurry is taken up and the excess slurry on the surface of the metal roller is scraped off by a doctor blade, only the slurry in the mesh holes is left. The metal roller is in contact with the flexible insulating substrate 10, and the slurry in the mesh holes is transferred to the surface of the flexible insulating substrate 10 by combining pressure and rotation of the metal roller, forming a continuous coating. The depth and shape of the mesh holes on the metal roller can be used to form the interface bonding layer 20 with a thickness of 2-50 μm. In addition, in the slot coating process, the slurry formed by any one of acrylic resin, epoxy resin, polyimide precursor or polyurethane is placed in the metal coating roller, and a gap is formed on the metal coating roller. A constant pressure is applied to the slurry in the metal coating roller by a pressure pump to maintain a certain flow rate, and the speed of the metal coating roller is further combined to make the slurry flow through the gap and uniformly lay and deposit on the surface of the flexible insulating substrate 10. Thus, by adjusting the slurry flow rate and the moving speed parameters of the metal coating roller, the interface bonding layer 20 with a thickness of 2-50 μm is formed on the surface of the flexible insulating substrate 10. It should be noted that the gravure coating or slot coating process belongs to the prior art and will not be described in detail here.
[0049] By controlling the thickness of the interface bonding layer 20, the influence of the thickness of the substrate on the flexibility or the increase in the material cost can be effectively avoided.
[0050] Preferably, in step S3, the screen printing or inkjet printing process is used to form the conductive circuit pattern 30.
[0051] In the present embodiment, in the screen printing process, the desired conductive circuit is formed by a screen with a hollow pattern, and the slurry is extruded by a doctor blade to pass through the mesh holes and be transferred to the substrate. In the inkjet printing process, the conductive slurry is sprayed in the form of tiny droplets to the specific position of the substrate according to the conductive circuit pattern 30, and the desired conductive circuit is formed by accumulation.
[0052] By adopting the screen printing or inkjet printing process, high-precision and accurate printing according to the conductive circuit pattern 30 on the surface of the interface bonding layer 20 can be realized to form the conductive circuit. Compared with the method of making flexible circuit board by etching copper-clad plate, the present method consumes less conductive slurry, improving the utilization rate of materials.
[0053] Preferably, in step S5, the protective layer 40 is formed by screen printing insulating ink and curing, or by hot pressing a cover film.
[0054] In the present embodiment, the insulating ink can be printed on the area of the conductive circuit to be protected through a silk screen printing process, and after curing, the insulating ink protection layer 40 is formed. The pre-prepared cover film can also be integrally attached to the surface of the conductive circuit to be protected through a hot-pressing process to form the cover film protection layer 40.
[0055] Preferably, according to the manufacturing method of any one of claims 6 to 9, after step S5, it further comprises step S6: using a die-cutting process to cut the shape of the protection layer 40, the interface bonding layer 20 and the flexible insulating substrate 10.
[0056] By using a die-cutting process to trim the excess part of the protection layer 40, the interface bonding layer 20 and the flexible insulating substrate 10, the manufacturing of the flexible circuit board for light emitting device is completed.
[0057] Embodiment Three Based on the embodiments one and two, the present embodiment further provides a single-layer flexible circuit board for LED soft light strip and a manufacturing method thereof: S1: using a polyester film with a thickness of 50 μm as the flexible insulating substrate, and performing online plasma cleaning on the surface to remove contaminants and improve the surface energy; S2: using a slot coater to uniformly coat an acrylic resin glue solution on the surface of the cleaned PET film, and passing the coated flexible insulating substrate through an oven at 80°C to 120°C for segmented curing, finally forming a transparent interface bonding layer with a thickness of about 10 μm and a micro-rough surface structure on the surface of the flexible insulating substrate. Through the interface bonding layer with a micro-rough surface structure, the adhesion of the conductive paste to the interface bonding layer can be further improved; S3: using a silk screen printing process, specifically, using a 300-mesh polyester screen, and printing a high-conductivity, low-temperature curing silver paste on the surface of the aforementioned interface bonding layer to form a designed parallel LED light strip conductive circuit pattern (line width 0.5 mm, pitch 1.0 mm). The flexible insulating substrate with the conductive circuit pattern is sent to a pre-drying device for pre-drying at 80°C for 5 minutes to complete the preliminary shaping of the conductive circuit pattern; S4: sending the pre-dried flexible insulating substrate into a tunnel furnace for sintering at 150°C in air for 20 minutes. The organic carrier in the silver paste is fully decomposed and volatilized, and a dense conductive network is formed between the silver particles, obtaining a conductive circuit with a square resistance of less than 20 mΩ / □; S5: Using a screen printing process, a layer of white epoxy resist ink is printed on all conductive circuit areas except the LED pad and terminal connection area. Then it is cured under UV light irradiation to form a white protective layer with a thickness of about 25 μm. The white layer can effectively reflect the light emitted by the LED, improving the front brightness and light color uniformity of the lamp strip; S6: Using a precision die-cutting machine, the whole board is punched into a strip-shaped LED soft lamp strip with a predetermined width.
[0058] The LED soft lamp strip circuit board produced in this embodiment has a material utilization rate of more than 95% (only the printed part consumes silver paste), avoiding the waste of more than 60% of copper etching in traditional processes. The process flow is simplified from 8-10 steps to 5-6 steps, and the production cycle is shortened by about 40%. The white protective layer improves the light-emitting efficiency of the lamp strip by about 15%.
[0059] Example Four Based on Examples One and Two, this embodiment further provides a double-layer flexible circuit board for high-end curved light-emitting devices and a manufacturing method thereof: S1: Using a polyimide film with a thickness of 25 μm as a flexible insulating substrate; S2: Using a gravure coating process, a layer of polyimide precursor solution is coated on the PI film. After high-temperature imidization, a first interfacial bonding layer with a thickness of 5 μm is formed; S3: Using an inkjet printing device, the conductive paste prepared from nano-silver conductive ink is precisely printed on the first interfacial bonding layer to form a first layer of conductive circuit pattern, and then sintered at 180°C to form a first layer of conductive circuit; S4: Using ultraviolet laser, the first layer of conductive circuit and the first layer of interfacial bonding layer are ablated at the predetermined interconnection position to form a micro via hole; S5: A layer of epoxy resin is coated on the first layer of interfacial bonding layer and the first layer of conductive circuit and then cured to form a second interfacial bonding layer with a thickness of 8 μm; Using screen printing, the conductive paste prepared from nano-silver conductive ink is filled into the micro via hole, and a second layer of conductive circuit pattern is printed on the surface of the second interfacial bonding layer, and then heat-cured to form a second conductive circuit, so that the two layers of conductive circuit are vertically interconnected through the micro via hole; S6: Using a vacuum hot pressing process, a white polyimide cover film (thickness 25 μm) pre-coated with a thermosetting adhesive is accurately aligned and pressed onto the surface of the second interfacial bonding layer and the second conductive circuit. The adhesive layer flows and fills the gap between the circuits under high temperature and pressure, protecting the second conductive circuit; S7: The second conductive circuit connection pad window is reserved on the window of the cover film protective layer.
[0060] The embodiment realizes high-density double-layer interconnection circuit, total thickness is only 70 μm, and has excellent flexibility and bending reliability.
[0061] Embodiment five On the basis of the embodiment one and the embodiment two, the embodiment further provides a double-layer flexible circuit board for a light-emitting device with high light reflection performance and a manufacturing method thereof. S1: a white reflective PET film with a thickness of 100 μm is used as a flexible insulating substrate, and the substrate has high reflectivity; S2: a modified polyurethane adhesive is roll-coated on the circuit forming surface of the white PET film, and a flexible interface bonding layer with a thickness of about 15 μm is formed by 100 ℃ hot air curing. The polyurethane layer has good adhesion with the white PET substrate and the subsequent paste, and has low elastic modulus, and can withstand severe bending.
[0062] S3: copper paste is used as conductive paste, and the copper paste is screen-printed to form a conductive circuit pattern in a printing environment with nitrogen protection atmosphere, and then sintered in a sintering furnace under nitrogen protection at 250 ℃ for 30 minutes to form a conductive circuit.
[0063] S4: a transparent polyurethane protective varnish with a thickness of 5 μm is coated on the interface bonding layer and the conductive circuit surface by using micro-gravure coating technology, and is cured. It is used for enhancing insulation and protection, and does not significantly affect the reflectivity.
[0064] The embodiment combines the substrate with reflection function and low-cost copper paste to realize the circuit function, and obtain high surface reflectivity (>95%), which is beneficial to improve the brightness of the backlight module and reduce the power consumption. The full additive process combined with the use of copper paste reduces the overall material cost by about 50% compared with the traditional copper-clad plate etching process.
[0065] The above is a specific description of the preferred embodiment of the application, but the application is not limited to the described embodiments, and those skilled in the art can make various equivalent modifications or replacements without departing from the spirit of the application. These equivalent modifications or replacements are all included in the scope defined by the claims of the present application.
Claims
1. A flexible circuit board for an additive light-emitting device, characterized in that, It includes a flexible insulating substrate, an interface bonding layer disposed on the surface of the flexible insulating substrate, a conductive circuit pattern formed on the interface bonding layer, and a protective layer covering the non-connected areas of the conductive circuit pattern. The material of the interface bonding layer is at least one of acrylic resin, epoxy resin, polyimide precursor or polyurethane.
2. The flexible circuit board for the additive process light-emitting device according to claim 1, characterized in that, The conductive circuit pattern is formed by printing and sintering conductive paste. The conductive paste includes conductive filler and resin binder. The conductive filler is made of at least one of silver powder, silver flakes, copper powder, and silver-copper alloy powder.
3. The flexible circuit board for the additive process light-emitting device according to claim 2, characterized in that, The protective layer is an insulating ink layer or a cover film.
4. The flexible circuit board for the additive process light-emitting device according to claim 1, characterized in that, The flexible insulating substrate is a polyimide film or a polyester film.
5. The flexible circuit board for the additive process light-emitting device according to claim 1, characterized in that, It also includes at least one second interface bonding layer disposed on the conductive line pattern and a second conductive line pattern formed on the second interface bonding layer, wherein the second conductive line pattern is electrically connected to the lower conductive line pattern through conductive vias.
6. A method for manufacturing a flexible circuit board for an additive light-emitting device, characterized in that, Includes the following steps: S1: Provides a flexible insulating substrate; S2: An interface bonding layer is formed on at least one surface of the flexible insulating substrate; S3: Print conductive paste on the interface bonding layer to form a conductive circuit pattern; S4: The printed conductive paste is cured and sintered to form a dense conductive circuit. S5: A protective layer is formed in the non-connected area of the conductive line pattern.
7. The manufacturing method according to claim 6, characterized in that, In step S2, the interface bonding layer with a thickness of 2-50 μm is formed by gravure coating or slot coating process.
8. The manufacturing method according to claim 6, characterized in that, In step S3, the conductive circuit pattern is formed using screen printing or inkjet printing processes.
9. The manufacturing method according to claim 6, characterized in that, In step S5, the protective layer is formed by screen printing insulating ink and curing it, or by hot-pressing and laminating a cover film.
10. The manufacturing method according to any one of claims 6 to 9, characterized in that, After step S5, step S6 is also included: using a die-cutting process to cut the shape of the protective layer, the interface bonding layer and the flexible insulating substrate.