Flexible circuit board based on pure addition method and manufacturing method thereof

Abstract

The invention discloses a flexible circuit board based on a pure addition method and a manufacturing method thereof. The method comprises the following steps: providing a substrate insulating layer; printing a first conductive layer on one side of the substrate insulating layer according to preset circuit design data to form a semi-finished flexible circuit board; and printing a first protective layer on the first conductive layer of the semi-finished flexible circuit board to obtain a target flexible circuit board. According to the manufacturing method, circuit manufacturing and protective film manufacturing are both achieved through a pure addition method, material reduction of an original base material is avoided, materials such as a dry film or liquid medicine influencing the environment are not applied, damage to the environment can be effectively reduced, and cost can be effectively reduced.

Description

Technical Field

[0001] The invention relates to the field of flexible circuit board manufacturing, and in particular to a pure addition process flexible circuit board and a manufacturing method thereof. Background Art

[0002] In recent years, with the advent of the information explosion era, the lightweight design of consumer electronic products has become the mainstream direction of research and development. Flexible circuit boards are one of the most important components of the electronic information industry and are applied to various new fields, including mobile phones, tablet computers, digital cameras, drones, various smart wearable products, various LCD screens and other terminal electronic products. With the rapid development of Internet of Vehicles and Internet of Things technologies, the application scope of flexible circuit boards will be further expanded to the fields of automobiles and smart homes.

[0003] At present, the process flow of circuit manufacturing in the flexible circuit board industry is: dry film pasting - circuit exposure - development - copper plating / copperization - dry film pasting - etching - film removal. This circuit manufacturing method is called a subtractive process, which means that after a series of treatments on the original substrate, the substrate copper on the original substrate is partially removed to form a circuit (that is, the original substrate is subtracted on the material to form the circuit). This subtractive process, from the perspective of the environment, the recycling of dry film and chemicals in the process will have an impact on the environment; for enterprises, the cost of materials and labor also shows that this process is not the most preferred.

[0004] Therefore, developing a new circuit manufacturing method to reduce damage to the environment and reduce costs has become a major competitive direction among companies. Summary of the invention

[0005] In view of this, an embodiment of the present invention provides a flexible circuit board based on a pure additive process and a method for manufacturing the same, so as to solve the problems of great environmental damage and high cost in the existing flexible circuit board manufacturing technology based on a subtractive process.

[0006] The present invention provides a method for manufacturing a flexible circuit board based on a pure additive process, the method comprising:

[0007] Providing a substrate insulation layer;

[0008] Printing a first conductive layer on one side of the substrate insulating layer according to preset circuit design data to form a semi-finished flexible circuit board;

[0009] A first protective layer is printed on the first conductive layer of the semi-finished flexible circuit board to obtain a target flexible circuit board.

[0010] Optionally, printing the first conductive layer on one side of the substrate insulating layer according to preset circuit design data includes:

[0011] Determining inkjet printing parameters of the inkjet printer according to the preset circuit design data;

[0012] Providing a conductive ink, and printing the conductive ink onto one side of the insulating layer of the substrate using the inkjet printer according to the inkjet printing parameters;

[0013] The substrate insulating layer printed with the conductive ink is sequentially subjected to a drying process and a sintering and curing process, so that the conductive ink forms the first conductive layer.

[0014] Optionally, printing the first conductive layer on one side of the substrate insulating layer according to preset circuit design data includes:

[0015] Determining screen printing parameters of the screen printing machine according to the preset circuit design data;

[0016] Providing conductive powder, and printing the conductive powder onto one side of the substrate insulating layer using the screen printing machine according to the screen printing parameters;

[0017] The base insulating layer printed with the conductive powder is baked so that the conductive powder forms the first conductive layer.

[0018] Optionally, after printing the first conductive layer on one side of the substrate insulating layer, the method further comprises:

[0019] The first conductive layer on the substrate insulating layer is subjected to copper electroplating so that the thickness of the first conductive layer reaches a first preset thickness, thereby obtaining the semi-finished flexible circuit board.

[0020] Optionally, printing a first protective layer on the first conductive layer of the semi-finished flexible circuit board includes:

[0021] providing a first thermosetting polyimide;

[0022] Performing pickling treatment on the semi-finished flexible circuit board;

[0023] Using a screen printing method, printing the provided first thermosetting polyimide on the side of the semi-finished flexible circuit board having the first conductive layer after pickling;

[0024] Allowing the semi-finished flexible circuit board after screen printing to stand for a first preset time;

[0025] According to the first curing parameter, the semi-finished flexible circuit board after the static treatment is pre-cured; according to the second curing parameter, the semi-finished flexible circuit board after the pre-curing treatment is post-cured; and according to the first preset baking parameter, the semi-finished flexible circuit board after the post-curing treatment is baked.

[0026] Optionally, after printing the first protective layer on the first conductive layer of the semi-finished flexible circuit board, the method further includes:

[0027] Inverting the semi-finished flexible circuit board printed with the first protective layer;

[0028] Printing a second conductive layer on a side of the semi-finished flexible circuit board away from the first protective layer in the same manner as printing the first conductive layer, to form a semi-finished double-sided board;

[0029] The second protective layer is printed on the second conductive layer of the semi-finished double-sided board in the same manner as the first protective layer is printed.

[0030] Optionally, after printing the second conductive layer on a side of the semi-finished flexible circuit board away from the first protective layer, the method further comprises:

[0031] The second conductive layer on the semi-finished flexible circuit board is subjected to copper electroplating so that the thickness of the second conductive layer reaches a second preset thickness, thereby obtaining the semi-finished double-sided board.

[0032] Optionally, before printing the first protective layer on the first conductive layer of the semi-finished flexible circuit board, the method further includes:

[0033] Printing a first outer layer circuit on the first conductive layer of the semi-finished flexible circuit board according to the preset circuit design data;

[0034] Correspondingly, printing a first protective layer on the first conductive layer of the semi-finished flexible circuit board includes:

[0035] Printing the first protective layer on the first outer layer circuit of the semi-finished flexible circuit board Before printing the first protective layer on the first conductive layer of the semi-finished flexible circuit board, the method further includes:

[0036] Printing a first outer layer circuit on the first conductive layer of the semi-finished flexible circuit board according to the preset circuit design data;

[0037] Correspondingly, printing a first protective layer on the first conductive layer of the semi-finished flexible circuit board includes:

[0038] The first protective layer is printed on the first outer layer circuit of the semi-finished flexible circuit board.

[0039] Optionally, printing a first outer layer circuit on the first conductive layer of the semi-finished flexible circuit board according to the preset circuit design data includes:

[0040] According to the preset circuit design data, providing a second thermosetting polyimide having an opening;

[0041] Performing pickling treatment on the semi-finished flexible circuit board;

[0042] Printing the second thermosetting polyimide having the opening on the side of the semi-finished flexible circuit board having the first conductive layer after pickling by inkjet printing or screen printing;

[0043] Allowing the semi-finished flexible circuit board after printing to stand for a second preset time;

[0044] According to the third curing parameter, the semi-finished flexible circuit board after the static treatment is pre-cured; according to the fourth curing parameter, the semi-finished flexible circuit board after the pre-curing treatment is post-cured; and according to the second preset baking parameter, the semi-finished flexible circuit board after the post-curing treatment is baked;

[0045] Based on the opening of the second thermosetting polyimide printed on the semi-finished flexible circuit board, the semi-finished flexible circuit board after baking is subjected to copper electroplating, so that the opening forms an interlayer copper-plated hole.

[0046] Optionally, after printing the first protective layer on the first outer layer circuit of the semi-finished flexible circuit board, the method further includes:

[0047] Inverting the semi-finished flexible circuit board printed with the first protective layer;

[0048] Printing a second conductive layer on a side of the semi-finished flexible circuit board away from the first protective layer in the same manner as printing the first conductive layer, to form a semi-finished double-sided board;

[0049] Printing a second outer layer circuit on the second conductive layer of the semi-finished double-sided board in the same manner as printing the first outer layer circuit;

[0050] The second protective layer is printed on the second outer layer circuit of the semi-finished double-sided board in the same manner as the first protective layer is printed.

[0051] Optionally, after printing the second conductive layer on a side of the semi-finished flexible circuit board away from the first protective layer, the method further comprises:

[0052] The second conductive layer on the semi-finished flexible circuit board is subjected to copper electroplating so that the thickness of the second conductive layer reaches a second preset thickness, thereby obtaining the semi-finished double-sided board.

[0053] In addition, the present invention also provides a flexible circuit board based on a pure additive process, which is manufactured using the aforementioned manufacturing method.

[0054] The beneficial effects of the present invention are as follows: first, a substrate insulating layer is provided, and a first conductive layer is directly printed on the substrate insulating layer according to preset circuit design data, which is equivalent to using an additive method to form a first conductive layer with a circuit function on the substrate insulating layer, so as to obtain a circuit that meets the design requirements. In this process, the original substrate (the original substrate is the substrate insulating layer at this time) is not subjected to material processing, and the original substrate will not be subjected to material reduction, and materials such as dry films or potions that have an impact on the environment will not be applied, and both material costs and labor costs are effectively reduced; after the circuit is completed to obtain a semi-finished flexible circuit board, a first protective layer is directly printed on the semi-finished flexible circuit board, which is also equivalent to using an additive method to form a first protective layer with a protective function on the semi-finished flexible circuit board. In this process, the original substrate (the original substrate is the semi-finished flexible circuit board at this time) is not subjected to material processing, and the original substrate will not be subjected to material reduction, and materials such as dry films or potions that have an impact on the environment are not applied, which further reduces costs; the entire manufacturing method is based on a pure additive method to form a circuit, which can effectively reduce damage to the environment and reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The features and advantages of the present invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the present invention in any way. In the accompanying drawings:

[0056] Figure 1 A flow chart of a method for manufacturing a flexible circuit board based on a pure additive process in Embodiment 1 of the present invention is shown;

[0057] Figure 2 The cross-sectional structure diagram of the substrate insulating layer in the first embodiment of the present invention is shown;

[0058] Figure 3 The cross-sectional structure diagram of the substrate insulating layer printed with the first conductive layer when the single-sided board is manufactured in the first embodiment of the present invention is shown;

[0059] Figure 4The cross-sectional structure diagram of a semi-finished flexible circuit board obtained after copper electroplating is completed during single-sided board manufacturing in the first embodiment of the present invention is shown;

[0060] Figure 5 The cross-sectional structure diagram of the target flexible circuit board obtained after the first protective layer is printed when the single-sided board is manufactured in the first embodiment of the present invention;

[0061] Figure 6 The cross-sectional structure diagram of the substrate insulating layer printed with the first conductive layer when manufacturing a double-sided board or a multi-layer board in the first embodiment of the present invention is shown;

[0062] Figure 7 The cross-sectional structure diagram of a semi-finished flexible circuit board obtained by copper electroplating the first conductive layer during the production of a double-sided board or a multi-layer board in the first embodiment of the present invention is shown;

[0063] Figure 8 The cross-sectional structure diagram of a semi-finished flexible circuit board printed with a first protective layer during double-sided board production in the first embodiment of the present invention is shown;

[0064] Fig. 9 The cross-sectional structure diagram of a semi-finished flexible circuit board printed with a second conductive layer during double-sided board production in the first embodiment of the present invention is shown;

[0065] Fig.10 The cross-sectional structure diagram of a semi-finished double-sided board obtained by copper electroplating the second conductive layer during the production of the double-sided board in the first embodiment of the present invention is shown;

[0066] Fig.11 The cross-sectional structure diagram of a target flexible circuit board printed with a second protective layer during double-sided board manufacturing in the first embodiment of the present invention is shown;

[0067] Fig.12 The cross-sectional structure diagram of a semi-finished flexible circuit board obtained after printing a second thermosetting polyimide with openings during the manufacture of a multilayer board in the first embodiment of the present invention is shown;

[0068] Fig.13 The cross-sectional structure diagram of a semi-finished flexible circuit board obtained after the second thermosetting polyimide is subjected to copper electroplating to form interlayer copper-plated holes during the manufacture of a multilayer board in the first embodiment of the present invention is shown;

[0069] Fig.14 The cross-sectional structure diagram of a semi-finished flexible circuit board obtained after printing the first protective layer during the manufacture of the multilayer board in the first embodiment of the present invention is shown;

[0070] Fig.15The cross-sectional structure diagram of a semi-finished flexible circuit board with a second conductive layer formed when the multilayer board is manufactured in the first embodiment of the present invention is shown;

[0071] Fig.16 The cross-sectional structure diagram of a semi-finished double-sided board obtained after the second conductive layer is subjected to copper electroplating during the manufacture of the multi-layer board in the first embodiment of the present invention is shown;

[0072] Fig.17 The cross-sectional structure diagram of a semi-finished double-sided board printed with a second outer layer circuit formed when a multi-layer board is manufactured in the first embodiment of the present invention is shown;

[0073] Fig.18 The cross-sectional structure diagram of the target flexible circuit board formed when the multilayer board is manufactured in the first embodiment of the present invention is shown.

[0074] The description of each reference numeral is as follows:

[0075] 1. substrate insulating layer, 2. first conductive layer, 3. first electroplated copper layer, 4. first protective layer, 5. second conductive layer, 6. second electroplated copper layer, 7. second protective layer, 8. second thermosetting polyimide, 9. interlayer copper-plated hole, 81. opening. DETAILED DESCRIPTION

[0076] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0077] Embodiment 1

[0078] This embodiment provides a method for manufacturing a flexible circuit board based on a pure additive process, such as Figure 1 As shown, including:

[0079] S1: Provide a substrate insulation layer;

[0080] S2: Printing a first conductive layer on one side of the substrate insulating layer according to preset circuit design data to form a semi-finished flexible circuit board;

[0081] S3: Printing a first protective layer on the first conductive layer of the semi-finished flexible circuit board to obtain a target flexible circuit board.

[0082] In this embodiment, a substrate insulating layer is first provided, and a first conductive layer is directly printed on the substrate insulating layer according to preset circuit design data, which is equivalent to using an additive method to form a first conductive layer with a circuit function on the substrate insulating layer to obtain a circuit that meets the design requirements. In this process, the original substrate (the original substrate is the substrate insulating layer at this time) is not processed on the material, and the original substrate will not be reduced in material. At the same time, materials such as dry films or potions that have an impact on the environment will not be applied, and both material costs and labor costs are effectively reduced; after the circuit is completed to obtain a semi-finished flexible circuit board, a first protective layer is directly printed on the semi-finished flexible circuit board, which is also equivalent to using an additive method to form a first protective layer with a protective function on the semi-finished flexible circuit board. In this process, the original substrate (the original substrate is the semi-finished flexible circuit board at this time) is not processed on the material, and the original substrate will not be reduced in material. No materials such as dry films or potions that have an impact on the environment are applied, which further reduces costs; the entire manufacturing method is based on a pure additive method to form a circuit, which can effectively reduce damage to the environment and reduce costs.

[0083] The following describes in detail each step of the manufacturing method of this embodiment.

[0084] In the present embodiment S1, the substrate insulating layer can be made of materials such as PI (i.e. polyimide), PET (i.e. polyethylene terephthalate), PEN (i.e. polyethylene naphthalate), etc. In the present embodiment, PI is specifically selected, and its cross-sectional structure is as follows: Figure 2 As shown, in Figure 2 In the figure, 1 is a substrate insulating layer.

[0085] In an optional embodiment, S2 includes:

[0086] S2A1: Determine inkjet printing parameters of the inkjet printer according to the preset circuit design data;

[0087] S2A2: providing a conductive ink, and printing the conductive ink onto one side of the insulating layer of the substrate using the inkjet printer according to the inkjet printing parameters;

[0088] S2A3: sequentially performing a drying treatment and a sintering and curing treatment on the substrate insulating layer printed with the conductive ink, so that the conductive ink forms the first conductive layer.

[0089] The above optional embodiment is based on the material properties of the conductive ink, and forms the first conductive layer by inkjet printing. This method can avoid the use of dry film, etching solution and other materials. On the one hand, it can avoid the damage of these materials to the original substrate and form a circuit that meets the design requirements by a pure additive method; on the other hand, it can also avoid the impact of these materials on the environment.

[0090] Specifically, in S2A1, the preset line design data is imported to determine the inkjet printing parameters, wherein the inkjet printing parameters include printing thickness, printing line width, nozzle pressure, nozzle speed, etc.

[0091] Specifically, in S2A2, the conductive ink is copper ink.

[0092] Specifically, in S2A3, the sintering and curing process is photon sintering and curing, and the process needs to be carried out according to the set curing temperature.

[0093] In another optional embodiment, S2 includes:

[0094] S2B1: Determine the screen printing parameters of the screen printing machine according to the preset circuit design data;

[0095] S2B2: providing conductive powder, and printing the conductive powder onto one side of the substrate insulating layer using the screen printing machine according to the screen printing parameters;

[0096] S2B3: baking the substrate insulating layer printed with the conductive powder so that the conductive powder forms the first conductive layer.

[0097] The above optional embodiment is based on the material properties of the conductive powder, and forms the first conductive layer by screen printing. This method can also avoid the use of dry film, etching solution and other materials, thereby avoiding these materials from damaging the original substrate and affecting the environment, thereby realizing the production of flexible circuit boards by pure additive method and effectively reducing costs.

[0098] Specifically, in S2B1, by importing the preset line design data, the screen printing parameters can be determined, wherein the screen printing parameters include printing line thickness, printing line width, screen frame pressure, scraper pressure and printing speed, etc.

[0099] Specifically, in S2B2, the conductive powder is specifically antioxidant nano copper powder.

[0100] Specifically, in S2B3, the baking process needs to be carried out according to the set baking temperature and baking time.

[0101] In this embodiment, the first conductive layer is printed according to the above steps S2A1 to S2A3 or steps S2B1 to S2B3 to obtain a cross-sectional structure of the substrate insulating layer printed with the first conductive layer. Figure 3 As shown, in Figure 3 In the figure, 2 is the first conductive layer.

[0102] In this embodiment S2, after printing the first conductive layer on one side of the substrate insulating layer, the method further includes:

[0103] The first conductive layer on the substrate insulating layer is subjected to copper electroplating so that the thickness of the first conductive layer reaches a first preset thickness, thereby obtaining the semi-finished flexible circuit board.

[0104] After the first conductive layer is printed on the substrate insulating layer according to steps S2A1 to S2A3 or steps S2B1 to S2B3, the thickness of the printed first conductive layer may not meet the design requirements. At this time, the first conductive layer can be electroplated with copper, and further thickened by electroplating with copper by a pure additive method, so that the thickness of the first conductive layer reaches a first preset thickness (i.e., the thickness required by the design requirements), thereby ultimately achieving a target flexible circuit board that meets the design requirements.

[0105] In the above copper electroplating process, electroplating parameters are determined according to the first preset thickness, including electroplating thickness, current density, electroplating current, electroplating voltage, electroplating time, etc.

[0106] Furthermore, after the first conductive layer on the base insulating layer is subjected to copper electroplating, the base insulating layer after the copper electroplating is also subjected to water washing and drying.

[0107] for Figure 3 The cross-sectional structure of the semi-finished flexible circuit board obtained after the substrate insulating layer with the first conductive layer is printed is as follows: Figure 4 As shown, in Figure 4 3 is the first electroplated copper layer formed after the electroplating copper treatment.

[0108] This embodiment S3 includes:

[0109] S31: providing a first thermosetting polyimide;

[0110] S32: performing pickling treatment on the semi-finished flexible circuit board;

[0111] S33: Printing the first thermosetting polyimide provided on the side of the semi-finished flexible circuit board having the first conductive layer after pickling by screen printing;

[0112] S34: allowing the semi-finished flexible circuit board after screen printing to stand for a first preset time;

[0113] S35: pre-curing the semi-finished flexible circuit board after the static treatment according to the first curing parameter; post-curing the semi-finished flexible circuit board after the pre-curing treatment according to the second curing parameter; and baking the semi-finished flexible circuit board after the post-curing treatment according to the first preset baking parameter.

[0114] Thermosetting polyimide (thermosetting PI for short) has good processability and plasticity. Therefore, in this embodiment, the first thermosetting polyimide provided can be formed on the first conductive layer by screen printing, which will not affect the original substrate and the environment; at the same time, the thermosetting PI also has excellent properties such as high temperature resistance, strong mechanical properties and corrosion resistance, and can be fully used as a protective film for semi-finished flexible circuit boards. The first thermosetting polyimide provided is printed onto the first conductive layer by the above method, which is equivalent to making the first protective layer on the first conductive layer by a pure additive method. It not only avoids the problems caused by the traditional subtractive method, but also realizes the function of the protective film, and obtains a flexible board product that meets actual needs.

[0115] Among them, before printing the first thermosetting polyimide, pickling the semi-finished flexible circuit board can make it easier to print the first thermosetting polyimide on its surface, which helps to improve the manufacturing accuracy of the first protective layer. After printing the first thermosetting polyimide, static treatment can help the molding of the first thermosetting polyimide, and then pre-curing, post-curing and baking treatments can fully ensure the molding effect of the first protective layer and ensure that the position and thickness of the first protective layer meet the design requirements, thereby improving its manufacturing accuracy.

[0116] Specifically, before S33 of this embodiment, the provided first thermosetting polyimide is stirred evenly, and then allowed to stand for a period of time before printing.

[0117] In this embodiment S35, the first curing parameter includes curing time and curing temperature, the second curing parameter also includes curing time and curing temperature, and the first preset baking parameter includes baking temperature and baking time. These parameters can be preset and adjusted according to actual conditions.

[0118] for Figure 4 After the first protective layer of the semi-finished flexible circuit board is printed, the cross-sectional structure of the target flexible circuit board is as follows: Figure 5 As shown, in Figure 5 In the figure, 4 is the first protective layer.

[0119] It should be understood that the target flexible circuit board formed by the above methods S1 to S3 in this embodiment is a single-sided board prepared by a pure additive process. For this single-sided board, the following two specific embodiments are listed.

[0120] Specific Example 1 (preparing a single-sided board with a line width of 50 μm, a line spacing of 50 μm, and a line thickness of 12 μm by a pure additive process):

[0121] (1) Forming the first conductive layer by inkjet printing: importing preset circuit design data, setting the printing thickness to 1 μm, adjusting the required printing line width to 28 μm according to the line thickness, adjusting parameters such as nozzle pressure and nozzle speed, and the inkjet printer automatically grasps the target point and starts printing the copper ink; after printing is completed, entering the drying process and checking the circuit; after the inspection, photon sintering is performed at a curing temperature of 500° C. to cure the first conductive layer;

[0122] Alternatively, the first conductive layer is formed by screen printing: the preset circuit design data is imported, the printing line thickness is set to 12 μm, and the required printing line width is adjusted to 50 μm according to the printing line thickness; antioxidant nano copper powder is selected as the conductive powder, a 325 mesh, 0.45 mm thick screen is selected, and parameters such as screen frame pressure, scraper pressure and printing speed are adjusted. The screen printer automatically grabs the target point and starts printing. After printing, it is placed in a nitrogen oven and baked at 80°C for 30 minutes, and then baked at 150°C for 1 hour; since the thickness of the first conductive layer printed by this method has reached 12 μm, when this method is used, there is no need to electroplating thicken the first conductive layer.

[0123] (2) When the first conductive layer is formed by inkjet printing, the first conductive layer is electroplated to increase thickness: the current density, electroplating current, electroplating voltage, and electroplating time are calculated according to the electroplating thickness (specifically 12 μm) and electroplating is started until the line width is 50 μm and the thickness is 12 μm. After electroplating, the layer is washed with water and dried.

[0124] (3) Screen printing the first protective layer: First, pickle the circuit board, then stir and mix the first thermosetting PI for 10 minutes and let it stand for 15 minutes. Then use 150# screen printing with a printing speed of 100 mm / sec. Let it stand for 5 minutes after printing, put it in a nitrogen oven for pre-curing at 80°C for 20 minutes, then post-curing at 150°C for 30 minutes. After cooling, put it in an oven and heat it to 150°C and keep it warm for 30 minutes. A single-sided board with a line width of 50μm, a line spacing of 50μm, and a line thickness of 12μm can be obtained.

[0125] Specific Example 2 (preparing a single-sided board with a line width of 100 μm, a line spacing of 100 μm, and a line thickness of 36 μm by a pure additive process):

[0126] (1) Forming the first conductive layer by inkjet printing: importing preset circuit design data, setting the printing thickness to 1 μm, adjusting the required printing line width to 30 μm according to the line thickness, adjusting parameters such as nozzle pressure and nozzle speed, and the inkjet printer automatically grasps the target point and starts printing the copper ink; after printing is completed, entering the drying process and checking the circuit; after the inspection, photon sintering is performed at a curing temperature of 500° C. to cure the first conductive layer;

[0127] Alternatively, the first conductive layer can be formed by screen printing: import the preset circuit design data, set the printing line thickness to 12μm, and adjust the required printing line width to 52μm according to the printing line thickness; select antioxidant nano copper powder as the conductive powder, select a 325 mesh, 0.45mm thick screen, adjust the screen frame pressure, scraper pressure and printing speed and other parameters, the screen printer automatically grabs the target point and starts printing. After printing, put it in a nitrogen oven and bake it at 80℃ for 30min, and then bake it at 150℃ for 1h.

[0128] (2) Since the thickness of the first conductive layer does not reach 36 μm when the first conductive layer is formed by inkjet printing or screen printing, the first conductive layer needs to be thickened by electroplating: the current density, electroplating current, electroplating voltage and electroplating time are calculated according to the electroplating thickness (specifically 36 μm) and electroplating is started until the line width is 100 μm and the thickness is 36 μm. After electroplating, the layer is washed with water and dried.

[0129] (3) Screen printing the first protective layer: First, pickle the circuit board, then stir and mix the first thermosetting PI for 10 minutes and let it stand for 15 minutes. Then use 150# screen printing with a printing speed of 100 mm / sec. Let it stand for 5 minutes after printing, put it in a nitrogen oven for pre-curing at 80°C for 20 minutes, then post-curing at 150°C for 30 minutes. After cooling, put it in an oven and heat it to 150°C and keep it warm for 30 minutes. A single-sided board with a line width of 100 μm, a line spacing of 100 μm, and a line thickness of 36 μm can be obtained.

[0130] When a double-sided board needs to be prepared, after S1 of this embodiment, the method further includes:

[0131] The provided base insulating layer is subjected to drilling processing to form a via hole on the base insulating layer.

[0132] The conductive holes are formed through the above steps, so that the layers of the double-sided board formed subsequently can be normally conductive, thereby ensuring the functionality of the double-sided board.

[0133] For the substrate insulating layer having the via hole formed therein, the first conductive layer is formed according to the method described in the aforementioned steps S2A1 to S2A3 or steps S2B1 to S2B3, and the cross-sectional structure of the obtained substrate insulating layer having the first conductive layer printed thereon is as follows: Figure 6 The cross-sectional structure of the semi-finished flexible circuit board obtained after the first conductive layer is electroplated with copper is shown in FIG. Figure 7 As shown; the first protective layer is formed according to the method described in the aforementioned steps S31 to S35, and the cross-sectional structure of the semi-finished flexible circuit board printed with the first protective layer is as shown Figure 8 shown.

[0134] When a double-sided board needs to be prepared, in this embodiment S3, after printing the first protective layer on the first conductive layer of the semi-finished flexible circuit board, the method further includes:

[0135] S36: inverting the semi-finished flexible circuit board printed with the first protective layer;

[0136] S37: Printing a second conductive layer on a side of the semi-finished flexible circuit board away from the first protective layer in the same manner as printing the first conductive layer, to form a semi-finished double-sided board;

[0137] S38: Printing a second protective layer on the second conductive layer of the semi-finished double-sided board in the same manner as printing the first protective layer.

[0138] Since the aforementioned first conductive layer and the first protective layer are both formed by inkjet printing or screen printing, in the specific production process, the side of the substrate insulating layer where the first conductive layer and the first protective layer are to be printed is placed upward to facilitate the printing of the first conductive layer and the first protective layer; when a double-sided board needs to be produced, it is necessary to place the other side of the substrate insulating layer (i.e., the side where the first conductive layer and the first protective layer are not printed) upward on the basis of the production of a single-sided board, that is, to invert the semi-finished flexible circuit board printed with the first protective layer so that the other side of the substrate insulating layer faces upward to facilitate the production of the second conductive layer and the second protective layer on this side; when the semi-finished flexible circuit board printed with the first protective layer is inverted, the second conductive layer is printed on the semi-finished circuit board in the same way as the first conductive layer is printed, and the second protective layer is printed on the semi-finished double-sided board in the same way as the first protective layer is printed, which can further realize the production of double-sided flexible circuit boards by a pure additive method, thereby also avoiding the problems of great environmental damage and high cost caused by the double-sided flexible circuit boards based on the subtractive method in the traditional technology.

[0139] In this embodiment S37, the method of printing the second conductive layer is the same as the method described in the aforementioned steps S2A1 to S2A3 or steps S2B1 to S2B3; in this embodiment S38, the method of printing the second protective layer is the same as the method described in the aforementioned steps S31 to S35, and will not be repeated here.

[0140] In this embodiment S37, when the thickness of the second conductive layer does not meet the design requirement (that is, does not reach the second preset thickness), after S37, the method further includes:

[0141] The second conductive layer on the semi-finished flexible circuit board is subjected to copper electroplating so that the thickness of the second conductive layer reaches a second preset thickness, thereby obtaining the semi-finished double-sided board.

[0142] Similar to the first conductive layer, when the thickness of the second conductive layer does not meet the design requirements, it needs to be thickened by copper electroplating.

[0143] In the process of making double-sided boards, Figure 8 The semi-finished flexible circuit board shown in FIG. 1 is printed with the second conductive layer, and the cross-sectional structure of the semi-finished flexible circuit board printed with the second conductive layer is as follows: Fig. 9 The cross-sectional structure of the semi-finished double-sided board obtained after the second conductive layer is electroplated with copper is shown in FIG. Fig.10 After the second protective layer is printed, the cross-sectional structure of the target flexible circuit board printed with the second protective layer is as shown Fig.11 shown in Figures 9 to 11 In the figure, 5 is the second conductive layer, 6 is the second electroplated copper layer, and 7 is the second protective layer.

[0144] For double-sided boards, the following two specific embodiments are also listed.

[0145] Specific Example 3 (preparing a double-sided board with a line width of 50 μm, a line spacing of 50 μm, and a line thickness of 12 μm by a pure additive process):

[0146] (1) The provided substrate insulating layer (substrate PI) is laser drilled to form a via hole.

[0147] (2) Forming the first conductive layer by inkjet printing: importing preset circuit design data, setting the printing thickness to 1 μm, adjusting the required printing line width to 28 μm according to the line thickness, adjusting parameters such as nozzle pressure and nozzle speed, and the inkjet printer automatically grasps the target point and starts printing the copper ink; after printing is completed, entering the drying process and checking the circuit; after the inspection, photon sintering is performed at a curing temperature of 500° C. to cure the first conductive layer;

[0148] Alternatively, the first conductive layer is formed by screen printing: the preset circuit design data is imported, the printing line thickness is set to 12 μm, and the required printing line width is adjusted to 50 μm according to the printing line thickness; antioxidant nano copper powder is selected as the conductive powder, a 325 mesh, 0.45 mm thick screen is selected, and parameters such as screen frame pressure, scraper pressure and printing speed are adjusted. The screen printer automatically grabs the target point and starts printing. After printing, it is placed in a nitrogen oven and baked at 80°C for 30 minutes, and then baked at 150°C for 1 hour; since the thickness of the first conductive layer printed by this method has reached 12 μm, when this method is used, there is no need to electroplating thicken the first conductive layer.

[0149] (3) When the first conductive layer is formed by inkjet printing, the first conductive layer is electroplated to increase thickness: the current density, electroplating current, electroplating voltage, and electroplating time are calculated according to the electroplating thickness (specifically 12 μm), and electroplating is started until the line width is 50 μm and the thickness is 12 μm. After electroplating, the layer is washed with water and dried.

[0150] (4) Screen printing the first protective layer: First, pickle the circuit board, then stir and mix the first thermosetting PI for 10 minutes and let it stand for 15 minutes. Then use 150# screen printing with a printing speed of 100mm / sec. After printing, let it stand for 5 minutes. Put it in a nitrogen oven for pre-curing at 80℃ for 20 minutes, then post-curing at 150℃ for 30 minutes. After cooling, put it in an oven and heat it to 150℃ and keep it warm for 30 minutes.

[0151] (5) After the single-sided circuit layer is prepared, the circuit board is inverted, and the second conductive layer, the second conductive layer thickening, and the second protective layer are printed in the same manner to obtain a double-sided board with a line width of 50 μm, a line spacing of 50 μm, and a line thickness of 12 μm.

[0152] Specific Example 4 (preparing a double-sided board with a line width of 100 μm, a line spacing of 100 μm, and a line thickness of 36 μm by a pure additive process):

[0153] (1) The provided substrate insulating layer (substrate PI) is laser drilled to form a via hole.

[0154] (2) Forming the first conductive layer by inkjet printing: importing preset circuit design data, setting the printing thickness to 1 μm, adjusting the required printing line width to 30 μm according to the line thickness, adjusting parameters such as nozzle pressure and nozzle speed, and the inkjet printer automatically grasps the target point and starts printing the copper ink; after printing is completed, entering the drying process and checking the circuit; after the inspection, photon sintering is performed at a curing temperature of 500° C. to cure the first conductive layer;

[0155] Alternatively, the first conductive layer can be formed by screen printing: import the preset circuit design data, set the printing line thickness to 12μm, and adjust the required printing line width to 52μm according to the printing line thickness; select antioxidant nano copper powder as the conductive powder, select a 325 mesh, 0.45mm thick screen, adjust the screen frame pressure, scraper pressure and printing speed and other parameters, the screen printer automatically grabs the target point and starts printing. After printing, put it in a nitrogen oven and bake it at 80℃ for 30min, and then bake it at 150℃ for 1h.

[0156] (3) Since the thickness of the first conductive layer does not reach 36 μm when the first conductive layer is formed by inkjet printing or screen printing, the first conductive layer needs to be thickened by electroplating: the current density, electroplating current, electroplating voltage and electroplating time are calculated according to the electroplating thickness (specifically 36 μm) and electroplating is started until the line width is 100 μm and the thickness is 36 μm. After electroplating, the layer is washed with water and dried.

[0157] (4) Screen printing the first protective layer: First, pickle the circuit board, then stir and mix the first thermosetting PI for 10 minutes and let it stand for 15 minutes. Then use 150# screen printing with a printing speed of 100 mm / sec. Let it stand for 5 minutes after printing, put it in a nitrogen oven for pre-curing at 80°C for 20 minutes, then post-curing at 150°C for 30 minutes. After cooling, put it in an oven and heat it to 150°C and keep it warm for 30 minutes.

[0158] (5) After the single-sided circuit layer is prepared, the circuit board is inverted, and the second conductive layer, the second conductive layer thickening, and the second protective layer are printed in the same manner to obtain a double-sided board with a line width of 100 μm, a line spacing of 100 μm, and a line thickness of 36 μm.

[0159] When a multilayer board needs to be prepared, after S1 of this embodiment, the method further includes:

[0160] The provided base insulating layer is subjected to drilling processing to form a via hole on the base insulating layer.

[0161] Similar to the double-sided board, the via holes are formed through the above steps to facilitate normal conduction between the layers of the subsequently formed multi-layer board, thereby ensuring the functionality of the multi-layer board.

[0162] It should be understood that in the process of manufacturing a multilayer board, for the substrate insulating layer with a via hole, both sides thereof need to be further manufactured on the basis of the manufacturing of a double-sided board. Therefore, for the substrate insulating layer with a via hole, it is the same as the manufacturing of a double-sided board, and it is necessary to first form a first conductive layer according to the method described in the aforementioned steps S2A1 to S2A3 or steps S2B1 to S2B3, that is, the obtained Figure 6 The substrate insulating layer printed with the first conductive layer as shown; then obtain Figure 7 The semi-finished flexible circuit board shown is obtained by copper electroplating of the first conductive layer.

[0163] For multilayer boards, before S3, the method also includes:

[0164] S4: Printing a first outer layer circuit on the first conductive layer of the semi-finished flexible circuit board according to the preset circuit design data.

[0165] By printing the first outer layer circuit on the first conductive layer, the first conductive layer can be used as the inner layer circuit, and the outer layer circuit (specifically the first outer layer circuit) is combined on the basis of the inner layer circuit to conveniently form a multi-layer board with multi-layer circuits; wherein, in the process of combining the outer layer circuit, the printing method is also used to form it, and the outer layer circuit can be further formed by a pure additive method, further reducing damage to the environment and reducing costs.

[0166] For a multilayer board, printing a first outer layer circuit on the first conductive layer of the semi-finished flexible circuit board according to the preset circuit design data specifically includes:

[0167] S41: providing a second thermosetting polyimide having an opening according to the preset circuit design data;

[0168] S42: performing pickling treatment on the semi-finished flexible circuit board;

[0169] S43: using an inkjet printing method or a screen printing method, printing the provided second thermosetting polyimide having the opening on the side of the semi-finished flexible circuit board having the first conductive layer after the acid washing treatment;

[0170] S44: allowing the semi-finished flexible circuit board after printing to stand for a second preset time;

[0171] S45: pre-curing the semi-finished flexible circuit board after the static treatment according to the third curing parameter; post-curing the semi-finished flexible circuit board after the pre-curing treatment according to the fourth curing parameter; and baking the semi-finished flexible circuit board after the post-curing treatment according to the second preset baking parameter;

[0172] S46: Based on the opening of the second thermosetting polyimide printed on the semi-finished flexible circuit board, the semi-finished flexible circuit board after baking is subjected to electroplating copper treatment, so that the opening forms an interlayer copper-plated hole.

[0173] In the process of printing the first outer layer circuit, a second thermosetting polyimide with an opening is first provided. On the one hand, it is convenient to subsequently form the first outer layer circuit that meets the design requirements based on the opening; on the other hand, it is convenient to form the first outer layer circuit by a pure additive method based on the material properties of the thermosetting polyimide, avoiding the problems caused by the traditional subtractive method.

[0174] In the process of printing the first outer layer circuit, after providing a second thermosetting polyimide with an opening, the processing process of the semi-finished flexible circuit board is similar to the processing process of the finished flexible circuit board in the process of printing the first protective layer, which can fully ensure the molding effect and production accuracy of the second thermosetting polyimide; after the molding of the second thermosetting polyimide is fully completed, copper electroplating is performed based on the opening, so that the opening forms an interlayer copper-plated hole, and the first outer layer circuit can be formed by combining the interlayer copper-plated hole and the second thermosetting polyimide, which is convenient for forming a multilayer board using a pure additive method.

[0175] This embodiment is for Figure 7 The cross-sectional structure of the semi-finished flexible circuit board obtained by copper electroplating the first conductive layer is as shown in FIG. Fig.12 The cross-sectional structure of the semi-finished flexible circuit board obtained after the copper electroplating process is completed to form interlayer copper-plated holes is as shown in Fig.13 As shown. Fig.12 and Fig.13 In the figure, 8 is a second thermosetting polyimide with an opening, 81 is an opening, and 9 is an interlayer copper-plated hole.

[0176] For multilayer boards, S3 is specifically:

[0177] The first protective layer is printed on the first outer layer circuit of the semi-finished flexible circuit board.

[0178] For a multilayer board, it is necessary to first form a first outer layer circuit according to the above steps S41 to S46. After the first outer layer circuit is formed, a first protective layer is printed on the first outer layer circuit according to the same method as the above steps S31 to S35 to protect the first outer layer circuit and the first conductive layer.

[0179] This embodiment is based on Fig.13 The cross-sectional structure of the semi-finished flexible circuit board obtained after printing the first protective layer is as shown in FIG. Fig.14 shown.

[0180] For a multilayer board, after S3, the method further includes:

[0181] S39: inverting the semi-finished flexible circuit board printed with the first protective layer;

[0182] S310: Printing a second conductive layer on a side of the semi-finished flexible circuit board away from the first protective layer in the same manner as printing the first conductive layer, to form a semi-finished double-sided board;

[0183] S311: Printing a second outer layer circuit on the second conductive layer of the semi-finished double-sided board in the same manner as printing the first outer layer circuit;

[0184] S312: Printing a second protective layer on the second outer layer circuit of the semi-finished double-sided board in the same manner as printing the first protective layer.

[0185] In the process of making the circuit on the other side of the multilayer board, similar to the double-sided board, the semi-finished flexible circuit board printed with the first protective layer is first inverted to facilitate the circuit making on the other side by the pure additive method; then the second conductive layer is printed in the same way as the first conductive layer, and after printing the second conductive layer, the second outer layer circuit is printed in the same way as the first outer layer circuit, so that in the process of making the circuit on the other side, the second outer layer circuit can be further formed by the pure additive method, and a multilayer board that meets the requirements can be further formed, and the problems caused by the traditional subtractive method for making multilayer boards can be avoided; after the printing of the second outer layer circuit is completed, the second protective layer is printed on the basis of the first outer layer circuit in the same way as the printing of the first protective layer, so as to obtain a multilayer flexible board product that truly meets the actual needs.

[0186] Similarly, during the process of printing the second conductive layer, if the thickness of the second conductive layer does not reach the second preset thickness, after printing the second conductive layer on the side of the semi-finished flexible circuit board away from the first protective layer, the method further includes:

[0187] The second conductive layer on the semi-finished flexible circuit board is subjected to copper electroplating so that the thickness of the second conductive layer reaches a second preset thickness, thereby obtaining the semi-finished double-sided board.

[0188] In the manufacturing process of the multilayer board, similar to the double-sided board, if the thickness of the second conductive layer does not reach the second preset thickness, the second conductive layer is thickened by copper electroplating to reach the second preset thickness.

[0189] Specifically, the above S310 is implemented according to the method described in steps S2A1 to S2A3 or steps S2B1 to S2B3, and the cross-sectional structure of the semi-finished flexible circuit board with the second conductive layer is as follows: Fig.15 The cross-sectional structure of the semi-finished double-sided board obtained after copper electroplating is as shown in FIG. Fig.16 As shown; in the above S311, according to steps S41 to S46, the cross-sectional structure of the semi-finished double-sided board printed with the second outer layer circuit is as shown Fig.17 As shown; the above S312 is implemented according to steps S31 to S35, and the cross-sectional structure of the target flexible circuit board is formed as shown Fig.18 shown.

[0190] For the multilayer board, the following two specific embodiments are also listed.

[0191] Specific Example 5 (preparation of a multilayer board with a line width of 50 μm, a line spacing of 50 μm, and a line thickness of 12 μm by a pure additive process):

[0192] (1) The provided substrate insulating layer (substrate PI) is laser drilled to form a via hole.

[0193] (2) Forming the first conductive layer by inkjet printing: importing preset circuit design data, setting the printing thickness to 1 μm, adjusting the required printing line width to 28 μm according to the line thickness, adjusting parameters such as nozzle pressure and nozzle speed, and the inkjet printer automatically grasps the target point and starts printing the copper ink; after printing is completed, entering the drying process and checking the circuit; after the inspection, photon sintering is performed at a curing temperature of 500° C. to cure the first conductive layer;

[0194] Alternatively, the first conductive layer is formed by screen printing: the preset circuit design data is imported, the printing line thickness is set to 12 μm, and the required printing line width is adjusted to 50 μm according to the printing line thickness; antioxidant nano copper powder is selected as the conductive powder, a 325 mesh, 0.45 mm thick screen is selected, and parameters such as screen frame pressure, scraper pressure and printing speed are adjusted. The screen printer automatically grabs the target point and starts printing. After printing, it is placed in a nitrogen oven and baked at 80°C for 30 minutes, and then baked at 150°C for 1 hour; since the thickness of the first conductive layer printed by this method has reached 12 μm, when this method is used, there is no need to electroplating thicken the first conductive layer.

[0195] (3) When the first conductive layer is formed by inkjet printing, the first conductive layer is electroplated to increase thickness: the current density, electroplating current, electroplating voltage, and electroplating time are calculated according to the electroplating thickness (specifically 12 μm), and electroplating is started until the line width is 50 μm and the thickness is 12 μm. After electroplating, the layer is washed with water and dried.

[0196] (4) Printing the second thermosetting PI with openings by screen printing: First, pickle the circuit board, stir and mix the second thermosetting PI for 10 minutes and let it stand for 15 minutes, then import the preset circuit design data and select 150# screen printing, the printing speed is 100mm / sec, let it stand for 5 minutes after printing, put it in a nitrogen oven at 80℃ for estimated curing for 20 minutes, then post-curing at 150℃ for 30 minutes, cool it down, put it in an oven to heat up to 150℃, and keep it warm for 30 minutes.

[0197] (5) Electroplating to form interlayer copper-plated holes: Calculate the current density, electroplating current, electroplating voltage, electroplating time and other parameters according to the electroplating thickness and start electroplating. When the electroplating fills the conductive holes, wash with water and dry.

[0198] (6) Screen printing the first protective layer: First, pickle the circuit board, then stir and mix the first thermosetting PI for 10 minutes and let it stand for 15 minutes. Then use 150# screen printing with a printing speed of 100 mm / sec. Let it stand for 5 minutes after printing, put it in a nitrogen oven for pre-curing at 80°C for 20 minutes, then post-curing at 150°C for 30 minutes. After cooling, put it in an oven and heat it to 150°C and keep it warm for 30 minutes.

[0199] (7) After the single-sided circuit layer is prepared, the circuit board is inverted and the second conductive layer, the second conductive layer thickening, the second outer layer circuit and the second protective layer are printed in the same manner to obtain a multilayer board with a line width of 50 μm, a line spacing of 50 μm and a line thickness of 12 μm.

[0200] Specific Example 6 (preparing a multilayer board with a line width of 100 μm, a line spacing of 100 μm, and a line thickness of 36 μm by a pure additive process):

[0201] (1) The provided substrate insulating layer (substrate PI) is laser drilled to form a via hole.

[0202] (2) Forming the first conductive layer by inkjet printing: importing preset circuit design data, setting the printing thickness to 1 μm, adjusting the required printing line width to 30 μm according to the line thickness, adjusting parameters such as nozzle pressure and nozzle speed, and the inkjet printer automatically grasps the target point and starts printing the copper ink; after printing is completed, entering the drying process and checking the circuit; after the inspection, photon sintering is performed at a curing temperature of 500° C. to cure the first conductive layer;

[0203] Alternatively, the first conductive layer can be formed by screen printing: import the preset circuit design data, set the printing line thickness to 12μm, and adjust the required printing line width to 52μm according to the printing line thickness; select antioxidant nano copper powder as the conductive powder, select a 325 mesh, 0.45mm thick screen, adjust the screen frame pressure, scraper pressure and printing speed and other parameters, the screen printer automatically grabs the target point and starts printing. After printing, put it in a nitrogen oven and bake it at 80℃ for 30min, and then bake it at 150℃ for 1h.

[0204] (3) Since the thickness of the first conductive layer does not reach 36 μm when the first conductive layer is formed by inkjet printing or screen printing, the first conductive layer needs to be thickened by electroplating: the current density, electroplating current, electroplating voltage and electroplating time are calculated according to the electroplating thickness (specifically 36 μm) and electroplating is started until the line width is 100 μm and the thickness is 36 μm. After electroplating, the layer is washed with water and dried.

[0205] (4) Printing the second thermosetting PI with openings by screen printing: First, pickle the circuit board, stir and mix the second thermosetting PI for 10 minutes and let it stand for 15 minutes, then import the preset circuit design data and select 150# screen printing, the printing speed is 100mm / sec, let it stand for 5 minutes after printing, put it in a nitrogen oven at 80℃ for estimated curing for 20 minutes, then post-curing at 150℃ for 30 minutes, cool it down, put it in an oven to heat up to 150℃, and keep it warm for 30 minutes.

[0206] (5) Electroplating to form interlayer copper-plated holes: Calculate the current density, electroplating current, electroplating voltage, electroplating time and other parameters according to the electroplating thickness and start electroplating. When the electroplating fills the conductive holes, wash with water and dry.

[0207] (6) Screen printing the first protective layer: First, pickle the circuit board, then stir and mix the first thermosetting PI for 10 minutes and let it stand for 15 minutes. Then use 150# screen printing with a printing speed of 100 mm / sec. Let it stand for 5 minutes after printing, put it in a nitrogen oven for pre-curing at 80°C for 20 minutes, then post-curing at 150°C for 30 minutes. After cooling, put it in an oven and heat it to 150°C and keep it warm for 30 minutes.

[0208] (7) After the single-sided circuit layer is prepared, the circuit board is inverted and the second conductive layer, the second conductive layer thickening, the second outer layer circuit and the second protective layer are printed in the same manner to obtain a multilayer board with a line width of 100 μm, a line spacing of 100 μm and a line thickness of 36 μm.

[0209] In the above embodiments, no matter it is a single-sided board, a double-sided board or a multi-layer board, the entire manufacturing method is based on a pure additive process, which can effectively reduce damage to the environment and reduce costs.

[0210] Embodiment 2

[0211] This embodiment provides a flexible circuit board based on a pure additive process, which is manufactured using the method for manufacturing a flexible circuit board based on a pure additive process described in the first embodiment.

[0212] The flexible circuit board in this embodiment, whether it is a single-sided board, a double-sided board or a multi-layer board, its circuit production and protective film production are all realized based on the pure additive method, which will not cause material reduction on the original substrate, and no materials such as dry film or potion that have an impact on the environment are used. It can effectively avoid the problems of great damage to the environment and high cost in the flexible circuit board production technology based on the subtractive method, effectively reduce damage to the environment and reduce costs.

[0213] The manufacturing method of the flexible circuit board based on the pure additive method in this embodiment is the same as the method steps described in Example 1. Therefore, for details not provided in this embodiment, please refer to Example 1 and Figures 1 to 18 The specific description of this embodiment will not be repeated here.

[0214] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A method for manufacturing a flexible circuit board based on a pure additive process, characterized in that: The method comprises: Providing a substrate insulation layer; Printing a first conductive layer on one side of the substrate insulating layer according to preset circuit design data to form a semi-finished flexible circuit board; A first protective layer is printed on the first conductive layer of the semi-finished flexible circuit board to obtain a target flexible circuit board.

2. The method according to claim 1, characterized in that: The method of printing the first conductive layer on one side of the substrate insulating layer according to the preset circuit design data comprises: Determining inkjet printing parameters of the inkjet printer according to the preset circuit design data; Providing a conductive ink, and printing the conductive ink onto one side of the insulating layer of the substrate using the inkjet printer according to the inkjet printing parameters; The substrate insulating layer printed with the conductive ink is sequentially subjected to a drying process and a sintering and curing process, so that the conductive ink forms the first conductive layer.

3. The method according to claim 1, characterized in that: The method of printing the first conductive layer on one side of the substrate insulating layer according to the preset circuit design data comprises: Determining screen printing parameters of the screen printing machine according to the preset circuit design data; Providing conductive powder, and printing the conductive powder onto one side of the substrate insulating layer using the screen printing machine according to the screen printing parameters; The base insulating layer printed with the conductive powder is baked so that the conductive powder forms the first conductive layer.

4. The method according to claim 2 or 3, characterized in that: After printing the first conductive layer on one side of the substrate insulating layer, the method further comprises: The first conductive layer on the substrate insulating layer is subjected to copper electroplating so that the thickness of the first conductive layer reaches a first preset thickness, thereby obtaining the semi-finished flexible circuit board.

5. The method according to claim 1, characterized in that: The step of printing a first protective layer on the first conductive layer of the semi-finished flexible circuit board comprises: providing a first thermosetting polyimide; Performing pickling treatment on the semi-finished flexible circuit board; Using a screen printing method, printing the provided first thermosetting polyimide on the side of the semi-finished flexible circuit board having the first conductive layer after pickling; Allowing the semi-finished flexible circuit board after screen printing to stand for a first preset time; According to the first curing parameter, the semi-finished flexible circuit board after the static treatment is pre-cured; according to the second curing parameter, the semi-finished flexible circuit board after the pre-curing treatment is post-cured; and according to the first preset baking parameter, the semi-finished flexible circuit board after the post-curing treatment is baked.

6. The method according to claim 1, characterized in that: After printing the first protective layer on the first conductive layer of the semi-finished flexible circuit board, the method further includes: Inverting the semi-finished flexible circuit board printed with the first protective layer; Printing a second conductive layer on a side of the semi-finished flexible circuit board away from the first protective layer in the same manner as printing the first conductive layer, to form a semi-finished double-sided board; The second protective layer is printed on the second conductive layer of the semi-finished double-sided board in the same manner as the first protective layer is printed.

7. The manufacturing method according to claim 6, characterized in that: After printing the second conductive layer on the side of the semi-finished flexible circuit board away from the first protective layer, the method further includes: The second conductive layer on the semi-finished flexible circuit board is subjected to copper electroplating so that the thickness of the second conductive layer reaches a second preset thickness, thereby obtaining the semi-finished double-sided board.

8. The manufacturing method according to claim 1, characterized in that: Before printing the first protective layer on the first conductive layer of the semi-finished flexible circuit board, the method further includes: Printing a first outer layer circuit on the first conductive layer of the semi-finished flexible circuit board according to the preset circuit design data; Correspondingly, printing a first protective layer on the first conductive layer of the semi-finished flexible circuit board includes: The first protective layer is printed on the first outer layer circuit of the semi-finished flexible circuit board.

9. The manufacturing method according to claim 8, characterized in that: The step of printing a first outer layer circuit on the first conductive layer of the semi-finished flexible circuit board according to the preset circuit design data comprises: According to the preset circuit design data, providing a second thermosetting polyimide having an opening; Performing pickling treatment on the semi-finished flexible circuit board; Printing the second thermosetting polyimide having the opening on the side of the semi-finished flexible circuit board having the first conductive layer after pickling by inkjet printing or screen printing; Allowing the semi-finished flexible circuit board after printing to stand for a second preset time; According to the third curing parameter, the semi-finished flexible circuit board after the static treatment is pre-cured; according to the fourth curing parameter, the semi-finished flexible circuit board after the pre-curing treatment is post-cured; and according to the second preset baking parameter, the semi-finished flexible circuit board after the post-curing treatment is baked; Based on the opening of the second thermosetting polyimide printed on the semi-finished flexible circuit board, the semi-finished flexible circuit board after baking is subjected to copper electroplating, so that the opening forms an interlayer copper-plated hole.

10. The manufacturing method according to claim 8, characterized in that: After printing the first protective layer on the first outer layer circuit of the semi-finished flexible circuit board, the method further includes: Inverting the semi-finished flexible circuit board printed with the first protective layer; Printing a second conductive layer on a side of the semi-finished flexible circuit board away from the first protective layer in the same manner as printing the first conductive layer, to form a semi-finished double-sided board; Printing a second outer layer circuit on the second conductive layer of the semi-finished double-sided board in the same manner as printing the first outer layer circuit; The second protective layer is printed on the second outer layer circuit of the semi-finished double-sided board in the same manner as the first protective layer is printed.

11. The manufacturing method according to claim 10, characterized in that: After printing the second conductive layer on the side of the semi-finished flexible circuit board away from the first protective layer, the method further includes: The second conductive layer on the semi-finished flexible circuit board is subjected to copper electroplating so that the thickness of the second conductive layer reaches a second preset thickness, thereby obtaining the semi-finished double-sided board.

12. A flexible circuit board based on a pure additive process, characterized in that: The method is as described in any one of claims 1 to 11.

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