Single-sided flexible circuit board and manufacturing method thereof

Abstract

The invention discloses a single-sided flexible circuit board and a manufacturing method thereof. The method comprises the following steps: providing a roll material double-sided board; performing exposure and development on the two side surfaces, so that a circuit exposure pattern is formed on the first side surface and the second side surface is not exposed, and obtaining a to-be-etched double-sided board; etching the two side surfaces to obtain a semi-finished coil circuit board; according to preset protective film pasting parameters, a protective film is pasted on the first side face of the semi-finished product coil material circuit board, single-piece cutting is carried out, and a plurality of single-piece double-sided boards are obtained; exposing and developing the two side surfaces of each single double-sided board, so that the protective film on the first side surface is not exposed and the second side surface is exposed, and obtaining a semi-finished single-sided board corresponding to each single double-sided board; and etching the two side surfaces of each semi-finished single-sided board to obtain a plurality of single-sided flexible circuit boards. Based on the support of the roll material double-sided board before etching and the protective film after etching, the problems of wrinkles, abnormal expansion and shrinkage and the like can be effectively avoided.

Description

Technical Field

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

[0002] As electronic devices develop towards lightweight, portability and multifunctionality, flexible printed circuits (FPC) have gradually become key components in the fields of smart phones, tablet computers, wearable devices, automotive electronics, medical equipment, etc. due to their advantages of being light, flexible, bendable and able to achieve high-density integrated circuit wiring in a limited space. They have broad application prospects.

[0003] Compared with double-layer and multi-layer flexible circuit boards, single-sided flexible circuit boards (single-sided panels or single-sided FPCs for short) have simple structures, low manufacturing costs, and better bending resistance. Single-sided FPCs are mainly composed of flexible substrates, conductive circuits, and protective films. They are usually used in scenarios where circuit connections are not complicated, such as keyboards, cables, and simple sensor modules. Single-sided FPCs can effectively save space and weight, which is especially important in portable electronic devices. In addition, single-sided FPCs have higher flexibility and are less prone to breakage because their conductive layer is only on one side, which can meet scenarios that require higher flexibility and bending resistance.

[0004] However, single-sided FPC still faces many challenges in the actual production process. Especially in the roll-to-roll process, due to the thinness of the product, it is very susceptible to uneven tension and pressure during the transmission process, humidity changes, and temperature control changes of the production equipment, resulting in product wrinkles, abnormal expansion and contraction, etc. These problems not only affect the appearance quality of the product, but may also lead to unstable circuit performance and even directly lead to product scrapping.

[0005] Therefore, developing a new production process that can effectively avoid wrinkles and abnormal expansion and shrinkage is of great significance to improving the production quality and efficiency of single-panel panels. Summary of the invention

[0006] In view of this, an embodiment of the present invention provides a single-sided flexible circuit board and a method for manufacturing the same, so as to solve the problems of product wrinkles, abnormal expansion and contraction, etc. that are easily occurred in the existing single-sided flexible circuit board manufacturing technology.

[0007] The present invention provides a method for manufacturing a single-sided flexible circuit board, the method comprising:

[0008] Provide double-sided board in roll form;

[0009] Expose and develop both sides of the double-sided board in a coil, so that a circuit exposure pattern is formed on the first side of the double-sided board in a coil, and the second side of the double-sided board in a coil is not exposed, thereby obtaining a double-sided board to be etched;

[0010] Etching both sides of the double-sided board to be etched to obtain a semi-finished coiled circuit board;

[0011] According to preset protective film sticking parameters, sticking a protective film on the first side of the semi-finished coiled circuit board, and cutting the semi-finished coiled circuit board after sticking the protective film into single sheets to obtain a plurality of single double-sided boards;

[0012] Expose and develop both sides of each single double-sided board so that the protective film on the first side of each single circuit board is not exposed and the second side of each single circuit board is exposed, thereby obtaining a semi-finished single-sided board corresponding to each single double-sided board;

[0013] Both side surfaces of each of the semi-finished single-sided boards are etched to obtain a plurality of single-sided flexible circuit boards.

[0014] Optionally, the exposing and developing both sides of the roll double-sided board so that a line exposure pattern is formed on the first side of the roll double-sided board and the second side of the roll double-sided board is not exposed to obtain the double-sided board to be etched, comprising:

[0015] Using a hot roller lamination method, both sides of the roll double-sided board are covered with a first negative photosensitive dry film;

[0016] Providing a first transparent negative film without a circuit pattern and an exposure negative film with a circuit pattern respectively;

[0017] Using the exposure film to perform line exposure and development on the first side of the roll-type double-sided board, so that the first negative photosensitive dry film on the first side of the roll-type double-sided board is partially dissolved to form the line exposure pattern;

[0018] The first transparent film is used to perform air exposure and development on the second side of the roll double-sided board, so that the first negative photosensitive dry film on the second side of the roll double-sided board is completely insoluble, so that the second side of the roll double-sided board is not exposed, and the double-sided board to be etched is obtained.

[0019] Optionally, both sides of the coiled double-sided board are conductive layers;

[0020] The method of etching both sides of the double-sided board to be etched to obtain a semi-finished coiled circuit board comprises:

[0021] Based on the circuit exposure pattern, etching the first side of the double-sided board to be etched, so that the conductive layer on the first side of the circuit board to be etched forms a circuit layer;

[0022] Etching the second side of the double-sided board to be etched so that the conductive layer on the second side of the circuit board to be etched is completely retained;

[0023] The first negative photosensitive dry film on both sides of the double-sided board to be etched is removed after etching to obtain the semi-finished coiled circuit board with single-sided circuits.

[0024] Optionally, both sides of the coiled double-sided board are conductive layers;

[0025] The step of exposing and developing both sides of each of the single double-sided boards so that the protective film on the first side of each of the single circuit boards is not exposed and the second side of each of the single circuit boards is exposed comprises:

[0026] Using a vacuum lamination method, according to preset dry film pressing parameters, the second negative photosensitive dry film is pressed on both sides of each single double-sided board;

[0027] A second transparent negative film without line pattern and a pure black negative film are provided respectively;

[0028] Using the second transparent film to perform air exposure and development on the first side of each single double-sided board, so that the second negative photosensitive dry film on the first side of each single double-sided board is completely insoluble, so that the protective film on the first side of each single double-sided board is not exposed;

[0029] The second side of each of the single double-sided boards is exposed and developed using the pure black film, so that the second negative photosensitive dry film on the second side of each of the single double-sided boards is completely dissolved, so that the conductive layer on the second side of each of the single double-sided boards is completely exposed, thereby obtaining the semi-finished single-sided board corresponding to each of the single double-sided boards.

[0030] Optionally, etching is performed on both sides of each of the semi-finished single-sided boards to obtain a plurality of single-sided flexible circuit boards, including:

[0031] Etching the first side surface of each of the semi-finished single-sided boards, so that the protective film on the first side surface of each of the semi-finished single-sided boards is retained;

[0032] Etching the second side surface of each of the semi-finished single-sided boards, so that the conductive layer on the second side surface of each of the semi-finished single-sided boards is etched away;

[0033] The second negative photosensitive dry film on the first side surface of each semi-finished single-sided board after etching is removed to obtain a plurality of the single-sided flexible circuit boards.

[0034] Optionally, the preset dry film pressing parameters include the second negative photosensitive dry film thickness, vacuuming time, first vacuum degree, pressing time and second vacuum degree; wherein the first vacuum degree refers to the vacuum degree during the vacuuming process during vacuum pressing, and the second vacuum degree refers to the vacuum degree during the pressing process during vacuum pressing.

[0035] Optionally, the thickness of the second negative photosensitive dry film ranges from 25 to 55 μm; and / or the vacuuming time ranges from 5 to 20 s; and / or the first vacuum degree is less than or equal to 20 Hpa; and / or the pressing time ranges from 5 to 15 s; and / or the second vacuum degree is less than or equal to 1 Hpa.

[0036] Optionally, the preset protective film pasting parameters include protective film thickness, pasting temperature, pasting time and pasting pressure.

[0037] Optionally, the thickness of the protective film is in the range of 30 to 60 μm; and / or the laminating temperature is in the range of 150 to 200° C.; and / or the laminating time is in the range of 90 to 120 s; and / or the laminating pressure is in the range of 90 to 120 kg / cm 2 .

[0038] In addition, the present invention also provides a single-sided flexible circuit board, which is manufactured using the aforementioned manufacturing method.

[0039] The beneficial effects of the present invention are as follows: the provided double-sided coil board is used as a coil substrate to produce a single-sided coil board, which can avoid the defect of the thin single-sided substrate of the traditional coil to a certain extent, and reduce wrinkles and abnormal expansion and contraction by utilizing the thickness of the double-sided coil board; for the provided double-sided coil board, both sides thereof are first exposed and developed, so that a circuit exposure pattern is formed on the first side, and the second side is not exposed, which can facilitate the subsequent production of a circuit layer on the first side during etching, so as to form a semi-finished coil circuit board with a single-sided circuit, and facilitate the subsequent formation of a single-sided coil board; during the exposure and development of the double-sided coil board and the etching of the double-sided coil board to be etched, due to the support of three layers of materials (the three layers of materials include two conductive layers and an insulating layer between the two conductive layers), the risk of damage caused by The wrinkles and abnormal expansion and contraction caused by the thin thickness; when the double-sided board to be etched is etched, a protective film is attached to its first side (i.e., the side with the circuit), and the subsequent single-sheet cutting and etching process are carried out after the protective film is attached. Due to the support of the protective film, the single-sided circuit can be supported and protected, further preventing the product from wrinkling and abnormal expansion and contraction; after cutting into single double-sided boards, the two sides of each single double-sided board are exposed and developed, so that the protective film on the first side of the single double-sided board is not exposed, while the second side is exposed, which can ensure that during the subsequent etching, the protective film on the first side and the inner layer of the circuit are not etched away, while the conductive layer exposed on the second side is etched away, and single-sided flexible circuit boards that meet the requirements are formed in batches;

[0040] The single-sided flexible circuit board and its manufacturing method of the present invention can effectively avoid the problems of wrinkles and abnormal expansion and contraction generated in the traditional coiled single-sided board process based on the thickness support of the coiled double-sided board before etching and the support of the protective film on the single-sided circuit after etching, and can effectively improve the yield and quality of single-sided board products. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] 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:

[0042] Figure 1 A flow chart showing a method for manufacturing a single-sided flexible circuit board in Embodiment 1 of the present invention is shown;

[0043] Figure 2 The cross-sectional structure diagram of the coiled double-sided board in the first embodiment of the present invention is shown;

[0044] Figure 3 The cross-sectional structure diagram of the roll-to-roll double-sided board covered with the first negative photosensitive dry film in the first embodiment of the present invention is shown;

[0045] Figure 4 A cross-sectional structural diagram of a semi-finished coiled circuit board in the first embodiment of the present invention is shown;

[0046] Figure 5 The cross-sectional structure diagram of the semi-finished coiled circuit board after the protective film is attached in the first embodiment of the present invention is shown;

[0047] Figure 6 It shows a cross-sectional structural diagram of a single double-sided board after the second negative photosensitive dry film is pressed onto both sides of the single double-sided board in the first embodiment of the present invention;

[0048] Figure 7 The cross-sectional structure diagram of a semi-finished single-sided board formed after exposure and development in the first embodiment of the present invention is shown;

[0049] Figure 8 The cross-sectional structure diagram of the single-sided flexible circuit board formed in the first embodiment of the present invention is shown.

[0050] The description of each reference numeral is as follows:

[0051] 1. Conductive layer, 2. Insulating layer, 3. First negative photosensitive dry film, 4. Circuit layer, 5. Protective film, 6. Protective film window, 7. Second negative photosensitive dry film. DETAILED DESCRIPTION

[0052] 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.

[0053] Embodiment 1

[0054] This embodiment provides a method for manufacturing a single-sided flexible circuit board, such as Figure 1 As shown, including:

[0055] S1: Provide double-sided board in rolls;

[0056] S2: exposing and developing both sides of the roll double-sided board, so that a circuit exposure pattern is formed on the first side of the roll double-sided board, and the second side of the roll double-sided board is not exposed, so as to obtain a double-sided board to be etched;

[0057] S3: etching both sides of the double-sided board to be etched to obtain a semi-finished coiled circuit board;

[0058] S4: sticking a protective film on the first side of the semi-finished coiled circuit board according to preset protective film sticking parameters, and cutting the semi-finished coiled circuit board after sticking the protective film into single sheets to obtain multiple single double-sided boards;

[0059] S5: exposing and developing both sides of each single double-sided board, so that the protective film on the first side of each single circuit board is not exposed, and the second side of each single circuit board is exposed, to obtain a semi-finished single-sided board corresponding to each single double-sided board;

[0060] S6: Etching both side surfaces of each of the semi-finished single-sided boards to obtain a plurality of single-sided flexible circuit boards.

[0061] In this embodiment, the provided double-sided coil board is used as the coil base material to produce the single-sided coil board, which can avoid the defect of the thin single-sided base material of the traditional coil to a certain extent, and reduce wrinkles and abnormal expansion and contraction by using the thickness of the double-sided coil board; for the provided double-sided coil board, both sides thereof are first exposed and developed, so that the first side forms a circuit exposure pattern, and the second side is not exposed, which can facilitate the subsequent production of a circuit layer on the first side during etching, so as to form a semi-finished coil circuit board with a single-sided circuit, and facilitate the subsequent formation of a single-sided coil board; during the exposure and development of the double-sided coil board and the etching of the double-sided coil board to be etched, due to the support of three layers of materials (the three-layer materials include two conductive layers and an insulating layer between the two conductive layers), the thickness of the double-sided coil board is effectively reduced. The problem of wrinkles and abnormal expansion and contraction caused by thinness is solved; when the double-sided board to be etched is completed, a protective film is attached to its first side (i.e., the side with the circuit), and the subsequent single-sheet cutting and etching process are carried out after the protective film is attached. Due to the support of the protective film, support and protection can be provided for the single-sided circuit, further preventing the product from wrinkling and abnormal expansion and contraction; after cutting into single double-sided boards, the two sides of each single double-sided board are exposed and developed, so that the protective film on the first side of the single double-sided board is not exposed, while the second side is exposed, which can ensure that during the subsequent etching, the protective film on the first side and the inner layer of the circuit are not etched away, while the conductive layer exposed on the second side is etched away, so as to form single-sided flexible circuit boards that meet the requirements in batches.

[0062] The manufacturing method of the single-sided flexible circuit board of this embodiment is based on the thickness support of the double-sided board before etching and the support of the protective film on the single-sided circuit after etching. It can effectively avoid the problems of wrinkles and abnormal expansion and contraction caused by the traditional roll-type single-sided board process, and can effectively improve the yield and quality of single-sided board products.

[0063] The following describes in detail each step of the manufacturing method of this embodiment.

[0064] In this embodiment S1, the double-sided board is cut into pieces, and its cross-sectional structure is as follows: Figure 2 As shown, in Figure 2 In the figure, 1 is the conductive layer on both sides of the double-sided board, and 2 is the insulating layer between the two conductive layers 1.

[0065] After S1, the method further includes:

[0066] Chemical cleaning of double-sided coils.

[0067] Through chemical cleaning, organic matter and other foreign matter on the conductive layer can be cleaned off, the roughness of the conductive layer can be increased, and the bonding strength between the subsequent negative photosensitive dry film and the conductive layer can be improved.

[0068] Preferably, this embodiment S2 includes:

[0069] S21: using a hot roller lamination method to cover both sides of the roll double-sided board with a first negative photosensitive dry film;

[0070] S22: providing a first transparent film without a line pattern and an exposure film with a line pattern respectively;

[0071] S23: using the exposure film to perform line exposure and development on the first side of the roll-type double-sided board, so that the first negative photosensitive dry film on the first side of the roll-type double-sided board is partially dissolved to form the line exposure pattern;

[0072] S24: using the first transparent film to perform air exposure and development on the second side of the roll double-sided board, so that the first negative photosensitive dry film on the second side of the roll double-sided board is completely insoluble, so that the second side of the roll double-sided board is not exposed, and the double-sided board to be etched is obtained.

[0073] Hot roller lamination is usually achieved by using a hot roller laminating machine, which usually uses a cylinder to control the lifting and lowering of the roller to ensure that the pressure of the rubber roller is uniform, so that the dry film can be evenly attached to the board, improving the lamination quality; and the hot roller laminating machine uses an inside-out heating method to help ensure that the dry film is evenly heated during the lamination process, improving the lamination effect. The provided exposure film is used for circuit exposure of the circuit surface (i.e., the first side) of the coiled double-sided board, which has a circuit pattern. The circuit pattern is usually made by photolithography or printing according to the circuit design drawings. Therefore, the first side of the coiled double-sided board is exposed and developed by using the provided exposure film, so that the first negative photosensitive dry film can be partially dissolved according to the pattern on the exposure film, thereby forming a circuit exposure pattern that meets the design requirements, which is convenient for exposing the conductive layer that needs to be exposed on the first side (i.e., the conductive layer area that needs to be etched away later) and forming the required circuit layer by etching. The first transparent film provided has no circuit pattern, and the first negative photosensitive dry film provided in this embodiment becomes difficult to be removed by the developer after exposure. Therefore, the second side surface (i.e., the non-circuit surface) of the roll double-sided board is exposed and developed using the first transparent film, which allows the light during exposure to pass through the first transparent film unimpeded, thereby preventing the first negative photosensitive dry film from being dissolved, and thus completely covering the inner conductive layer without exposing it, so that the conductive layer can be completely retained after subsequent etching.

[0074] In this embodiment S21, the cross-sectional structure of the roll double-sided board covered with the first negative photosensitive dry film is as follows: Figure 3 As shown, in Figure 3 In the figure, 3 is the first negative photosensitive dry film.

[0075] Preferably, this embodiment S3 includes:

[0076] S31: etching the first side of the double-sided board to be etched based on the circuit exposure pattern, so that the conductive layer on the first side of the circuit board to be etched forms a circuit layer;

[0077] S32: Etching the second side of the double-sided board to be etched, so that the conductive layer on the second side of the circuit board to be etched is completely retained;

[0078] S33: removing the first negative photosensitive dry film on both sides of the double-sided board to be etched after etching, to obtain the semi-finished coiled circuit board with single-sided circuits.

[0079] After the two sides of the coiled double-sided board are exposed and developed to form the double-sided board to be etched, the first side (i.e., the circuit side) is etched based on the formed circuit exposure pattern to form the required circuit layer, and the second side (non-circuit side) is completely retained based on the covering of the first negative photosensitive dry film. Finally, the remaining first negative photosensitive dry film on both sides (including the remaining first negative photosensitive dry film on the first side and the first negative photosensitive dry film retained on the second side) is removed to form a semi-finished coiled double-sided board with single-sided circuits that meets the circuit design requirements. In the above exposure, development and etching process, on the one hand, since the entire coiled flexible substrate is a double-sided board, it is not easy to wrinkle or expand and shrink abnormally based on the thickness characteristics of the double-sided board; on the other hand, the circuit can be formed on the single side of the double-sided board as needed, which is convenient for subsequent production into a single-sided flexible circuit board.

[0080] In this embodiment, after the two sides of the coiled double-sided board are exposed, developed and etched, the cross-sectional structure of the semi-finished coiled circuit board is as follows: Figure 4 As shown, in Figure 4 In the figure, 4 is a circuit layer formed on the conductive layer 1 on the first side (specifically, the upper side).

[0081] In this embodiment S4, the preset protective film pasting parameters include protective film thickness, pasting temperature, pasting time and pasting pressure.

[0082] Specifically, the thickness of the protective film is in the range of 30 to 60 μm; and / or the laminating temperature is in the range of 150 to 200° C.; and / or the laminating time is in the range of 90 to 120 s; and / or the laminating pressure is in the range of 90 to 120 kg / cm 2 .

[0083] Through the above-mentioned parameters such as bonding temperature, bonding time and bonding pressure, it is possible to ensure that a protective film with a thickness ranging from 30 to 60 μm is formed; and through the above-mentioned protective film of specific thickness, it is possible to ensure that the attached protective film can, on the one hand, prevent the product from being oxidized and scratched, and on the other hand, can provide good support for the subsequent exposure, development and etching of a single double-sided board. On the basis of forming the required single-sided flexible circuit board, the whole process can be protected from wrinkles and abnormal expansion and contraction, thereby improving the yield and quality of the formed single-sided flexible circuit board.

[0084] In this embodiment S4, the protective film has been pre-opened to facilitate the subsequent solder mask. The cross-sectional structure of the semi-finished coiled circuit board after the protective film is attached is as follows: Figure 5 As shown, in Figure 5 In the figure, 5 is a protective film, and 6 is a window of the protective film.

[0085] In S4, the semi-finished coiled circuit boards with protective film are cut into single sheets, which is convenient for subsequent processes with single flexible boards. In the single-sheet process, the flexible boards do not need to bear the tension of rewinding and unwinding, which can further reduce the risks of product expansion, shrinkage and wrinkling.

[0086] Preferably, this embodiment S5 includes:

[0087] S51: Using a vacuum lamination method, according to preset dry film pressing parameters, the second negative photosensitive dry film is pressed on both sides of each of the single double-sided boards;

[0088] S52: providing a second transparent film without line patterns and a pure black film respectively;

[0089] S53: using the second transparent film to perform air exposure and development on the first side of each single double-sided board, so that the second negative photosensitive dry film on the first side of each single double-sided board is completely insoluble, so that the protective film on the first side of each single double-sided board is not exposed;

[0090] S54: The second side of each of the single double-sided boards is exposed and developed using the pure black film, so that the second negative photosensitive dry film on the second side of each of the single double-sided boards is completely dissolved, so that the conductive layer on the second side of each of the single double-sided boards is completely exposed, thereby obtaining the semi-finished single-sided board corresponding to each of the single double-sided boards.

[0091] Due to the presence of the protective film window on the single double-sided board, the surface step difference is large. The vacuum lamination method can avoid the problem of uneven dry film lamination caused by the large step difference, so that the second negative photosensitive dry film can be pressed more evenly, which is convenient for the subsequent exposure, development and etching of each single double-sided board. Similar to the aforementioned first transparent film, the first side surface (i.e., the circuit surface, the side with the protective film) of each single double-sided board is exposed and developed by using the provided second transparent film without circuit patterns, which will allow the light during exposure to pass through the second transparent film without hindrance, so that the second negative photosensitive dry film is not dissolved at all, and the inner protective film is completely covered and not exposed, so that the protective film is completely retained after etching. The pure black film is completely different from the second transparent film. It has a strong light absorption property, so that the light will not penetrate it during the exposure process (that is, the entire area covered by the pure black film is the non-exposure area). The pure black film is used to expose and develop the second side of a single double-sided board (that is, the non-circuit side, the material is a conductive layer), so that the second negative photosensitive dry film on the entire second side can be a non-exposure area. Based on the characteristics of the second negative photosensitive dry film, its non-exposure area will react with the developer and be dissolved, so that the conductive layer on the second side of each single double-sided board can be completely exposed, which is convenient for subsequent etching to be completely removed, thereby forming the required single-sided flexible circuit board with only single-sided circuits.

[0092] In this embodiment S51, the preset dry film pressing parameters include the second negative photosensitive dry film thickness, vacuuming time, first vacuum degree, pressing time and second vacuum degree; wherein, the first vacuum degree refers to the vacuum degree during the vacuuming process during vacuum pressing, and the second vacuum degree refers to the vacuum degree during the pressing process during vacuum pressing.

[0093] Specifically, the thickness of the second negative photosensitive dry film ranges from 25 to 55 μm; and / or the vacuuming time ranges from 5 to 20 s; and / or the first vacuum degree is less than or equal to 20 Hpa; and / or the pressing time ranges from 5 to 15 s; and / or the second vacuum degree is less than or equal to 1 Hpa.

[0094] The above parameters can effectively overcome the height difference caused by the opening of the protective film window, forming a second negative photosensitive dry film thickness in the range of 25 to 55 μm; the above-mentioned specific thickness of the second negative photosensitive dry film thickness can not only provide better support for the subsequent single-sheet process, but also ensure that both sides of each single double-sided panel achieve the required exposure and development effect.

[0095] In this embodiment, after being cut into single sheets, the cross-sectional structure of the single double-sided board after the second negative photosensitive dry film is pressed on both sides is as follows: Figure 6 As shown, after the two sides of a single double-sided board are exposed and developed, the cross-sectional structure of the semi-finished single-sided board is formed as shown in FIG. Figure 7 As shown, in Figure 6 and Figure 7 7 is the second negative photosensitive dry film.

[0096] Preferably, this embodiment S6 includes:

[0097] S61: etching the first side surface of each of the semi-finished single-sided boards, so that the protective film on the first side surface of each of the semi-finished single-sided boards is retained;

[0098] S62: Etching the second side surface of each of the semi-finished single-sided boards, so that the conductive layer on the second side surface of each of the semi-finished single-sided boards is etched away;

[0099] S63: removing the second negative photosensitive dry film on the first side surface of each semi-finished single-sided board after etching to obtain a plurality of the single-sided flexible circuit boards.

[0100] After the two sides of a single double-sided board are exposed and developed to form a semi-finished single-sided board, the first side (i.e., the circuit side, the side with the protective film) is etched, and it is completely retained due to the covering of the second negative photosensitive dry film on its outer layer; the second side (i.e., the non-circuit side, the material is the conductive layer) is etched, and since the conductive layer on this side is completely exposed, the conductive layer on this side is completely etched away; finally, the second negative photosensitive dry film on the first side is removed, forming a single-sided flexible circuit board with only single-sided circuits. In the above etching process, due to the presence of the protective film and the second negative photosensitive dry film, the problem of product wrinkles and abnormal expansion and contraction caused by the product being too thin can be effectively prevented.

[0101] The cross-sectional structure of the single-sided flexible circuit board formed in this embodiment is as follows: Figure 8 shown.

[0102] Embodiment 2

[0103] This embodiment provides a single-sided flexible circuit board, which is manufactured using the manufacturing method of the single-sided flexible circuit board described in the first embodiment.

[0104] This embodiment is based on the thickness support of the double-sided board before etching and the support of the protective film on the single-sided circuit after etching. It can effectively avoid the problems of wrinkles and abnormal expansion and contraction caused by the traditional single-sided board process, and can effectively improve the yield and quality of single-sided board products.

[0105] The manufacturing method of the single-sided flexible circuit board in this embodiment is the same as the method steps described in the first embodiment. Therefore, for details not provided in this embodiment, please refer to the first embodiment and the second embodiment. Figure 1 to Figure 7 The specific description of this embodiment will not be repeated in detail.

[0106] 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 single-sided flexible circuit board, characterized in that: The method comprises: Provide double-sided board in roll form; Expose and develop both sides of the double-sided board in a coil, so that a circuit exposure pattern is formed on the first side of the double-sided board in a coil, and the second side of the double-sided board in a coil is not exposed, thereby obtaining a double-sided board to be etched; Etching both sides of the double-sided board to be etched to obtain a semi-finished coiled circuit board; According to preset protective film sticking parameters, sticking a protective film on the first side of the semi-finished coiled circuit board, and cutting the semi-finished coiled circuit board after sticking the protective film into single sheets to obtain a plurality of single double-sided boards; Expose and develop both sides of each single double-sided board so that the protective film on the first side of each single circuit board is not exposed and the second side of each single circuit board is exposed, thereby obtaining a semi-finished single-sided board corresponding to each single double-sided board; Both side surfaces of each of the semi-finished single-sided boards are etched to obtain a plurality of single-sided flexible circuit boards.

2. The method according to claim 1, characterized in that: The method of exposing and developing both sides of the double-sided board in coil material so that a line exposure pattern is formed on the first side of the double-sided board in coil material and the second side of the double-sided board in coil material is not exposed to obtain the double-sided board to be etched includes: Using a hot roller lamination method, both sides of the roll double-sided board are covered with a first negative photosensitive dry film; Providing a first transparent negative film without a circuit pattern and an exposure negative film with a circuit pattern respectively; Using the exposure film to perform line exposure and development on the first side of the roll-type double-sided board, so that the first negative photosensitive dry film on the first side of the roll-type double-sided board is partially dissolved to form the line exposure pattern; The first transparent film is used to perform air exposure and development on the second side of the roll double-sided board, so that the first negative photosensitive dry film on the second side of the roll double-sided board is completely insoluble, so that the second side of the roll double-sided board is not exposed, and the double-sided board to be etched is obtained.

3. The method according to claim 2, characterized in that: Both sides of the coiled double-sided board are conductive layers; The method of etching both sides of the double-sided board to be etched to obtain a semi-finished coiled circuit board comprises: Based on the circuit exposure pattern, etching the first side of the double-sided board to be etched, so that the conductive layer on the first side of the circuit board to be etched forms a circuit layer; Etching the second side of the double-sided board to be etched so that the conductive layer on the second side of the circuit board to be etched is completely retained; The first negative photosensitive dry film on both sides of the double-sided board to be etched is removed after etching to obtain the semi-finished coiled circuit board with single-sided circuits.

4. The method according to claim 1, characterized in that: Both sides of the coiled double-sided board are conductive layers; The step of exposing and developing both sides of each of the single double-sided boards so that the protective film on the first side of each of the single circuit boards is not exposed and the second side of each of the single circuit boards is exposed comprises: Using a vacuum lamination method, according to preset dry film pressing parameters, the second negative photosensitive dry film is pressed on both sides of each single double-sided board; A second transparent negative film without line pattern and a pure black negative film are provided respectively; Using the second transparent film to perform air exposure and development on the first side of each single double-sided board, so that the second negative photosensitive dry film on the first side of each single double-sided board is completely insoluble, so that the protective film on the first side of each single double-sided board is not exposed; The second side of each of the single double-sided boards is exposed and developed using the pure black film, so that the second negative photosensitive dry film on the second side of each of the single double-sided boards is completely dissolved, so that the conductive layer on the second side of each of the single double-sided boards is completely exposed, thereby obtaining the semi-finished single-sided board corresponding to each of the single double-sided boards.

5. The method according to claim 4, characterized in that: The two sides of each of the semi-finished single-sided panels are etched to obtain a plurality of single-sided flexible circuit boards, including: Etching the first side surface of each of the semi-finished single-sided boards, so that the protective film on the first side surface of each of the semi-finished single-sided boards is retained; Etching the second side surface of each of the semi-finished single-sided boards, so that the conductive layer on the second side surface of each of the semi-finished single-sided boards is etched away; The second negative photosensitive dry film on the first side surface of each semi-finished single-sided board after etching is removed to obtain a plurality of the single-sided flexible circuit boards.

6. The method according to claim 4, characterized in that: The preset dry film pressing parameters include the second negative photosensitive dry film thickness, vacuuming time, first vacuum degree, pressing time and second vacuum degree; wherein the first vacuum degree refers to the vacuum degree during the vacuuming process during vacuum pressing, and the second vacuum degree refers to the vacuum degree during the pressing process during vacuum pressing.

7. The manufacturing method according to claim 6, characterized in that: The thickness of the second negative photosensitive dry film ranges from 25 to 55 μm; and / or the vacuuming time ranges from 5 to 20 s; and / or the first vacuum degree is less than or equal to 20 Hpa; and / or the pressing time ranges from 5 to 15 s; and / or the second vacuum degree is less than or equal to 1 Hpa.

8. The manufacturing method according to claim 1, characterized in that: The preset protective film pasting parameters include protective film thickness, pasting temperature, pasting time and pasting pressure.

9. The manufacturing method according to claim 8, characterized in that: The thickness of the protective film is in the range of 30 to 60 μm; and / or the laminating temperature is in the range of 150 to 200° C.; and / or the laminating time is in the range of 90 to 120 s; and / or the laminating pressure is in the range of 90 to 120 kg / cm 2 .

10. A single-sided flexible circuit board, characterized in that: The method is manufactured by the manufacturing method according to any one of claims 1 to 9.

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