A method for processing a flexible circuit board and a flexible circuit board

Abstract

The present invention provides a method for processing a flexible circuit board and a flexible circuit board. The method includes: obtaining a flexible circuit board substrate and an original film; determining layout data; obtaining a finished film according to the layout data and the original film; preprocessing the flexible circuit board substrate to obtain a preprocessed flexible circuit board substrate; obtaining a first flexible circuit board according to the preprocessed flexible circuit board substrate and the finished film; obtaining a second flexible circuit board according to the first flexible circuit board and the finished film; and performing an etching process on the second flexible circuit board to obtain a target flexible circuit board. The present invention is beneficial to improving the accuracy of the circuit pattern on the flexible circuit board.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible printed circuit boards, and also relates to a processing method and a flexible printed circuit board for a flexible printed circuit board. Background Art

[0002] A flexible printed circuit board, also known as a "flexible board", is a printed circuit made of a flexible insulating substrate. The flexible circuit provides excellent electrical performance, can meet the design requirements of smaller and higher density installations, and also helps to reduce the assembly process and enhance reliability. In the process flow of manufacturing a flexible printed circuit board, it is necessary to remove part of the copper foil covering the surface of the flexible printed circuit board through etching to form the required circuit pattern. Etching is one of the key processes in the manufacture of flexible printed circuit boards, and it has an important impact on the quality and performance of flexible printed circuit boards. However, the existing etching process has problems such as too deep line depth and too large line width etched, and cannot meet the requirements of users for the accuracy of circuit patterns. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a processing method and a flexible printed circuit board for a flexible printed circuit board to improve the accuracy of the circuit pattern on the flexible printed circuit board.

[0004] To solve the above technical problems, the technical solution of the present invention is as follows:

[0005] In a first aspect of the present invention, there is provided a processing method for a flexible printed circuit board, including:

[0006] Obtaining a flexible printed circuit board substrate and an original film;

[0007] Determining layout data;

[0008] Obtaining a finished film according to the layout data and the original film;

[0009] Preprocessing the flexible printed circuit board substrate to obtain a preprocessed flexible printed circuit board substrate;

[0010] Obtaining a first flexible printed circuit board according to the preprocessed flexible printed circuit board substrate and the finished film;

[0011] Obtaining a second flexible printed circuit board according to the first flexible printed circuit board and the finished film;

[0012] Performing an etching process on the second flexible printed circuit board to obtain a target flexible printed circuit board.

[0013] Optionally, determining the layout data includes:

[0014] Obtaining accuracy information of the circuit pattern;

[0015] When the accuracy information of the circuit pattern meets the preset accuracy information, layout data is determined according to the preset layout conditions, the flexible circuit board substrate, and the original film.

[0016] Optionally, determining layout data according to the preset layout conditions, the flexible circuit board substrate, and the original film includes:

[0017] Obtaining original layout data according to the preset layout conditions, the flexible circuit board substrate, and the original film;

[0018] Converting the format of the original layout data according to a preset format to obtain layout data.

[0019] Optionally, obtaining a finished film according to the layout data and the original film includes:

[0020] Performing image exposure on the original film to obtain a first film;

[0021] Performing punching processing on the first film according to the layout data to obtain a second film;

[0022] Inspecting the second film, and if the inspection result meets the preset inspection conditions, the second film is the finished film.

[0023] Optionally, preprocessing the flexible circuit board substrate to obtain a preprocessed flexible circuit board substrate includes:

[0024] Performing a cleaning process on the flexible circuit board substrate to obtain a cleaned flexible circuit board substrate;

[0025] Performing a surface micro-etching process on the cleaned flexible circuit board substrate to obtain a micro-etched flexible circuit board substrate;

[0026] Performing an anti-oxidation process on the micro-etched flexible circuit board substrate to obtain a preprocessed flexible circuit board substrate.

[0027] Optionally, obtaining a first flexible circuit board according to the preprocessed flexible circuit board substrate and the finished film includes:

[0028] Putting the preprocessed flexible circuit board substrate into a coating device according to preset coating parameters for photoresist coating to obtain a flexible circuit board substrate with photoresist;

[0029] Putting the flexible circuit board substrate with photoresist into a baking device according to preset baking parameters for baking to obtain a baked flexible circuit board substrate;

[0030] Put the baked flexible circuit board substrate and the finished film into an exposure device for a first exposure treatment according to the first preset exposure parameters to obtain a flexible circuit board substrate after the first exposure;

[0031] Perform a first development treatment on the flexible circuit board substrate after the first exposure to obtain a first flexible circuit board.

[0032] Optionally, obtaining a second flexible circuit board according to the first flexible circuit board and the finished film includes:

[0033] Adjust the first preset exposure parameters according to the first flexible circuit board to obtain second preset exposure parameters;

[0034] Align the first flexible circuit board and the finished film to obtain an aligned first flexible circuit board and finished film;

[0035] Perform a second exposure treatment on the aligned first flexible circuit board and finished film to obtain a first flexible circuit board after the second exposure;

[0036] Perform a second development treatment on the first flexible circuit board after the second exposure to obtain a first flexible circuit board after the second development;

[0037] Perform a cleaning and drying treatment on the first flexible circuit board after the second development to obtain a second flexible circuit board.

[0038] Optionally, performing an etching treatment on the second flexible circuit board to obtain a target flexible circuit board includes:

[0039] Provide an etching solution;

[0040] Determine etching parameters according to the etching solution;

[0041] Put the second flexible circuit board into an etching device for etching treatment according to the etching parameters to obtain an etched second flexible circuit board;

[0042] Perform a degumming treatment on the second flexible circuit board to obtain a target flexible circuit board.

[0043] Optionally, the method further includes:

[0044] Perform an appearance inspection on the target flexible circuit board to obtain an appearance inspection result;

[0045] Perform a circuit pattern inspection on the target flexible circuit board to obtain a circuit pattern inspection result;

[0046] Screen the target flexible circuit board according to the appearance inspection result, the circuit pattern inspection result and preset qualified conditions to obtain a qualified target flexible circuit board.

[0047] In a second aspect of the present invention, a flexible circuit board is provided, which is manufactured by using the processing method of the flexible circuit board according to any one of the first aspects.

[0048] The above solution of the present invention has at least the following beneficial effects:

[0049] According to the determined layout data and the original film, a finished film is obtained. According to the pretreated flexible circuit board substrate and the finished film, a first flexible circuit board is obtained. Then, according to the first flexible circuit board and the finished film, a second flexible circuit board is obtained. Finally, the second flexible circuit board is etched to obtain a target flexible circuit board, which improves the accuracy of the circuit pattern on the target flexible circuit board, meets the customer's requirements for high-precision circuit patterns, and is beneficial to meeting customer requirements and improving the accuracy of the circuit pattern on the flexible circuit board. Description of the Drawings

[0050] Figure 1 is a schematic flow chart of the processing method of the flexible circuit board in the embodiment of the present invention;

[0051] Figure 2 is a schematic diagram of a partial circuit pattern after the first exposure in the embodiment of the present invention;

[0052] Figure 3 is a schematic diagram of the complete circuit pattern after the second exposure in the embodiment of the present invention.

[0053] Description of the reference numerals: 11 - partial circuit pattern, 12 - remaining circuit pattern. Detailed Embodiments

[0054] Hereinafter, exemplary embodiments of the present invention will be described in more detail with reference to the drawings. Although the exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present invention can be more thoroughly understood and the scope of the present invention can be fully conveyed to those skilled in the art.

[0055] As Figure 1 shown, an embodiment of the present invention provides a processing method for a flexible circuit board, including the following steps:

[0056] Step 101, obtain a flexible circuit board substrate and an original film;

[0057] Step 102, determine layout data;

[0058] Step 103: Obtain a finished film based on the typesetting data and the original film.

[0059] Step 104: Pretreat the flexible circuit board substrate to obtain a pretreated flexible circuit board substrate.

[0060] Step 105: Obtain a first flexible circuit board based on the pretreated flexible circuit board substrate and the finished film.

[0061] Step 106: Obtain a second flexible circuit board based on the first flexible circuit board and the finished film.

[0062] Step 107: Perform an etching process on the second flexible circuit board to obtain a target flexible circuit board.

[0063] In the embodiment of the present invention, for the method of processing a flexible circuit board, a finished film is obtained according to the determined typesetting data and the original film. A first flexible circuit board is obtained according to the pretreated flexible circuit board substrate and the finished film. Then, a second flexible circuit board is obtained according to the first flexible circuit board and the finished film. Finally, an etching process is performed on the second flexible circuit board to obtain a target flexible circuit board, improving the accuracy of the circuit pattern on the target flexible circuit board, meeting the customer's requirements for high-precision circuit patterns, and facilitating meeting customer requirements and improving the accuracy of the circuit pattern on the flexible circuit board.

[0064] In an optional embodiment of the present invention, step 101 includes:

[0065] Step 1011: Obtain a flexible circuit board substrate.

[0066] Specifically, a flexible circuit board substrate made of a corresponding material, such as a flexible circuit board substrate made of polyimide or polyester film, can be provided according to user requirements and the design requirements of the flexible circuit board. Quality inspection can also be performed on the provided flexible circuit board substrate to ensure that its surface is flat, without scratches or stains, to ensure the printing quality and accuracy of the circuit pattern etched on the flexible circuit board substrate subsequently. In addition, for the geometric data of the flexible circuit board substrate, such as length, width, and shape, etc., it is required to meet the preset design requirements to improve production efficiency.

[0067] Step 1012: Obtain an original film.

[0068] Specifically, the original film can be made of materials such as polycarbonate, polypropylene, polyethylene terephthalate, or polyvinyl chloride. According to the characteristics of various materials and the actual situation, specific materials can be selected.

[0069] In an alternative embodiment of the present invention, step 102 includes:

[0070] Step 1021, obtaining accuracy information of the circuit pattern;

[0071] Specifically, before manufacturing the circuit on the flexible circuit board, the user may provide a drawing of the circuit pattern, which may include accuracy requirements for the circuit pattern, such as the circuit pattern being flush with the outer edge of the flexible circuit board, or the accuracy of the circuit pattern being greater than 95%. Therefore, the accuracy information of the circuit pattern can be extracted from the user requirement information (such as the provided drawing of the circuit pattern) to understand the user's accuracy requirements for the circuit pattern.

[0072] Step 1022, when the accuracy information of the circuit pattern meets the preset accuracy information, determining layout data according to the preset layout conditions, the flexible circuit board substrate, and the original film.

[0073] Specifically, the preset accuracy information may be that the circuit pattern is flush with the outer edge of the flexible circuit board, or the accuracy is greater than 90%, etc. If the obtained accuracy information of the circuit pattern meets at least one of the preset accuracy information, the method of double exposure can be selected to manufacture the circuit on the flexible circuit board, so as to improve the accuracy of the circuit pattern and meet the user's requirements.

[0074] In an alternative embodiment of the present invention, step 1022 includes:

[0075] Step 10221, obtaining original layout data according to the preset layout conditions, the flexible circuit board substrate, and the original film;

[0076] Specifically, the preset layout conditions may include: reserving space at the edge of the layout, adding 5 crosses with a line width of 0.08 and 5 positioning holes with a diameter of 2.0, ensuring that these marks are clearly shown on the front, back, and etching line layers of the flexible circuit board substrate, and marking the punching positions on the character layer of the film. According to these preset layout conditions, as well as the data such as the length, width, and shape of the flexible circuit board substrate, and the data such as the material, length, width, and shape of the original film, layout design is carried out in graphic design software, such as CAD, to obtain a layout pattern, that is, the original layout data.

[0077] Step 10222, performing format conversion on the original layout data according to a preset format to obtain layout data.

[0078] Specifically, the format recognized by the device for manufacturing an image on the film later can be used as the preset format, and the original layout data is converted according to the preset format to obtain layout data with the preset format, which is convenient for inputting the layout data with the preset format into the image manufacturing device to manufacture an image on the film later, and is beneficial to improving production efficiency.

[0079] In an alternative embodiment of the present invention, step 103 includes:

[0080] Step 1031, perform image exposure on the original film to obtain a first film;

[0081] Specifically, first, check and adjust the layout data, such as checking whether the size content is correct, color adjustment, etc., to ensure that the layout data meets the production requirements. Then, according to the actual situation of printing on the machine (such as the printing quantity, material, etc.), perform layout on the layout data to ensure that it can be reasonably arranged and the layout is fully utilized on the original film. After that, output the layout data with a preset format to a laser imagesetter. The laser imagesetter is a key device for making films. It uses a laser beam to expose the original film to form a circuit image, and then uses an infrared laser to scan the film with the circuit image. After a series of chemical reactions, a stable image is formed, thereby obtaining the first film.

[0082] Step 1032, perform punching on the first film according to the layout data to obtain a second film;

[0083] Specifically, tools such as a punch, scissors, and cleaning cloth for punching the first film can be prepared in advance. The punch is a small tool specifically used for punching holes in the film. Use the punch to accurately punch the required small holes at the top of the first film. The distance and quantity should be determined according to actual needs (such as 5 crosses and 5 positioning holes). Use scissors to trim the black edges around the punched film (if any) to avoid affecting the use effect. Then, use the cleaning cloth to wipe the surface of the trimmed film to remove dust and stains, obtaining the second film.

[0084] Step 1033, inspect the second film. If the inspection result meets the preset inspection conditions, the second film is the finished film.

[0085] Specifically, the circuit image and the position and quantity of the holes in the layout data can be used as the preset inspection conditions to check whether the holes and circuit image on the second film are accurate and complete, etc. If the position and quantity of the holes on the second film match the position and quantity of the holes in the layout data, and the circuit image on the second film is consistent with the circuit image in the layout data, then the corresponding second film is the finished film. Otherwise, it needs to be repaired until it is qualified.

[0086] In an alternative embodiment of the present invention, step 104 includes:

[0087] Step 1041, perform cleaning treatment on the flexible circuit board substrate to obtain a cleaned flexible circuit board substrate;

[0088] Specifically, a water-based cleaning agent suitable for the flexible circuit board substrate can be selected. Such cleaning agents usually have the characteristics of low surface tension and low ion residue, and can effectively remove stains and impurities on the substrate surface. The cleaning method is as follows: Immerse the flexible circuit board substrate in the water-based cleaning agent to ensure that the cleaning agent can fully contact the substrate surface, and use an appropriate cleaning tool (such as a soft brush) to gently brush the substrate surface to remove stains and impurities. After that, deionized water can be used to further clean the flexible circuit board substrate. Deionized water can remove impurity ions in the water, thus avoiding secondary pollution to the surface of the flexible circuit board substrate. The flexible circuit board substrate can be placed in a clean drying device for drying to avoid the influence of moisture residue on the performance of the circuit board.

[0089] Step 1042: Perform surface micro-etching treatment on the cleaned flexible circuit board substrate to obtain the micro-etched flexible circuit board substrate;

[0090] Specifically, the cleaned flexible circuit board substrate can be put into a micro-etching solution of sulfuric acid, hydrochloric acid, nitric acid, or a system of hydrogen peroxide and sulfuric acid. The chemical substances in the micro-etching solution will selectively react with the surface of the flexible circuit board substrate, thereby removing the oxide layer on the surface of the flexible circuit board substrate and improving the adhesion of the flexible circuit board substrate to other substances. In addition, the micro-etched flexible circuit board substrate can be activated to improve the activity of the surface of the flexible circuit board substrate, making it easier to combine with materials (such as photoresist) in subsequent processes. Here, the activation treatment method can be to bombard and etch the flexible circuit board substrate with argon plasma or oxygen plasma, etc., so as to increase the roughness and activity of the surface of the flexible circuit board substrate.

[0091] Step 1043: Perform anti-oxidation treatment on the micro-etched flexible circuit board substrate to obtain the pre-treated flexible circuit board substrate.

[0092] Specifically, polytetrafluoroethylene, epoxy resin, or other anti-oxidation coatings can be coated on the micro-etched flexible circuit board substrate by spraying, dipping, brushing, etc. For example, epoxy resin has good adhesion and anti-oxidation properties, and its coating thickness can be between 5 microns and 25 microns; polytetrafluoroethylene has excellent chemical corrosion resistance and high-temperature stability, and its coating thickness can be between 1 micron and 10 microns. Then, the pre-treated flexible circuit board substrate is inspected to ensure that its anti-oxidation coating is uniform, bubble-free, and non-missing coating, so as to improve the anti-oxidation effect.

[0093] In an alternative embodiment of the present invention, step 105 includes:

[0094] Step 1051: Place the pretreated flexible circuit board substrate into a coating device according to preset coating parameters for photoresist coating, obtaining a flexible circuit board substrate with photoresist.

[0095] Specifically, the preset coating parameters may include: the coating speed range is 1 to 10 meters per minute, the coating thickness range is 0.5 to 5 microns, the spin coating speed is 200 to 3000 revolutions per minute, the coating temperature is 20 to 25 °C, and the humidity is 40% to 60% RH. Specific preset coating parameters can be selected according to different coating devices or coating processes. Use the coating device to evenly coat a layer of photoresist on the surface of the pretreated flexible circuit board substrate. Here, select a suitable photoresist model according to the requirements of the coating process. Different models of photoresists have different photosensitive characteristics, adhesion, and stability.

[0096] Step 1052: Place the flexible circuit board substrate with photoresist into a baking device according to preset baking parameters for baking, obtaining a baked flexible circuit board substrate.

[0097] Specifically, the preset baking parameters include: the pre-baking temperature is 80 °C to 120 °C, and the pre-baking time is 5 to 3 hours. Place the flexible circuit board substrate coated with photoresist into the baking device for pre-baking according to this preset baking parameter to remove the solvent in the photoresist and improve the adhesion between the photoresist and the flexible circuit board substrate.

[0098] Step 1053: Place the baked flexible circuit board substrate and the finished film into an exposure device according to the first preset exposure parameters for a primary exposure treatment, obtaining a flex circuit board substrate after the primary exposure.

[0099] Specifically, the character layer of the finished film contains punching marks, which are used to accurately align specific positions on the flexible circuit board substrate during the exposure process. Place the finished film on the alignment table of the exposure device (such as a lithography machine), and use the alignment system of the lithography machine (such as a microscope, a CCD camera (a digital camera with a charge-coupled device image sensor), etc.) to accurately align the punching marks on the character layer of the finished film with the corresponding marks on the flexible circuit board substrate. The alignment accuracy directly affects the graphic quality of the subsequent exposure.

[0100] Here, the first preset exposure parameters include an exposure time of 5 to 15 seconds and an exposure energy of 20 to 300 mJ / cm². Parameters such as the exposure time and exposure energy of the lithography machine can be set according to the photosensitive characteristics of the photoresist and the requirements of the exposure process. Among them, the exposure time needs to be adjusted according to the photosensitive characteristics of the photoresist and the intensity of the ultraviolet light source to ensure that the photoresist can be fully exposed and a clear circuit pattern can be formed. The exposure energy also needs to be controlled according to the photosensitive characteristics of the photoresist and the process requirements to ensure the uniformity of exposure and the accuracy of the circuit pattern. After that, the aligned flexible circuit board substrate is placed on the workbench of the lithography machine, and the lithography machine is started for exposure. During the exposure process, ultraviolet light passes through the transparent part of the finished film and irradiates the photoresist, triggering a chemical reaction of the photoresist, thereby obtaining the flexible circuit board substrate after the first exposure.

[0101] Step 1054: Perform a first development process on the flexible circuit board substrate after the first exposure to obtain a first flexible circuit board.

[0102] Specifically, for some photoresists and exposure process requirements, a post-baking process may be required after exposure. The flexible circuit board substrate after the first exposure can be placed in a baking device for post-baking according to the post-baking parameters of a post-baking temperature of 80°C to 120°C and a post-baking time of 5 to 3 hours to further enhance the adhesion between the photoresist and the flexible circuit board substrate and the stability of the circuit pattern.

[0103] After that, the flexible circuit board substrate after the post-baking process is placed in a developer (including an aqueous solution of tetramethylammonium hydroxide (TMAH), etc.), and a first development process is performed on the flexible circuit board substrate according to the preset development parameters. Here, the development parameters during the development process can include: the temperature of the developer is set between 43°C and 55°C. Within this temperature range, the developer can better dissolve the unexposed or incompletely exposed part of the photoresist while avoiding excessive corrosion of the flexible circuit board substrate; the concentration of the developer can be 1:8 or 1:6 (developer powder: deionized water); the development time is set between 2 and 5 minutes. Within this time range, the developer can fully dissolve the unexposed or incompletely exposed part of the photoresist while avoiding excessive erosion of the exposed part. The developer will dissolve the unexposed or incompletely exposed part of the photoresist to obtain a first flexible circuit board. After the development is completed, the first flexible circuit board needs to be rinsed with deionized water or pure water to remove the residual developer and impurities. After rinsing, the first flexible circuit board is dried to ensure the smooth progress of subsequent processes.

[0104] In an alternative embodiment of the present invention, step 106 includes:

[0105] Step 1061: Adjust the first preset exposure parameters according to the first flexible circuit board to obtain second preset exposure parameters;

[0106] Specifically, inspect the first flexible circuit board to check whether the exposure result is uniform and whether there are unexposed or overexposed areas. Adjust the first preset exposure parameters according to the effect of the first exposure. For example, if the first exposure is insufficient, appropriately increase the exposure energy in the first preset exposure parameters; if the first exposure is excessive, reduce the exposure energy in the first preset exposure parameters. If the first exposure time is short and the effect is good, then the exposure time in the first preset exposure parameters can be shortened; conversely, if the first exposure time is long and the effect is not ideal, then the exposure time in the first preset exposure parameters needs to be extended. Take the increased / decreased exposure energy and the shortened / extended exposure time as the second preset exposure parameters.

[0107] Step 1062: Align the first flexible circuit board and the finished film to obtain the aligned first flexible circuit board and finished film;

[0108] Specifically, place the first flexible circuit board on the alignment platform and fix it with a fixing fixture. Place the finished film above the first flexible circuit board and initially adjust its position to align it with the reference points or marks on the first flexible circuit board. Observe the alignment between the finished film and the first flexible circuit board through a microscope and make necessary fine adjustments. On the basis of the initial alignment, use a high-precision alignment device (such as a laser aligner) for precise alignment. By adjusting the relative positions between the finished film and the first flexible circuit board, ensure that the patterns between them are completely matched. During the alignment process, it is necessary to observe and adjust repeatedly to ensure the accuracy of the alignment. It should be noted that the circuit pattern on the finished film used here can be the same as the finished film used in the first exposure. The first exposure is used to define the main circuit pattern, while the second exposure may be used to enhance the edges of the pattern, repair defects, or form finer pattern features. The circuit pattern on the finished film used here can also be different from the finished film used in the first exposure. This is to further define or modify the circuit pattern on the basis of the first exposure. For example, the first exposure forms the main part of the circuit, while the second exposure is to add detail elements, holes, or connection lines, etc. The finished film can be selected according to the actual situation.

[0109] Step 1063: Perform a second exposure on the aligned first flexible circuit board and finished film to obtain the first flexible circuit board after the second exposure;

[0110] Specifically, after the first flexible circuit board and the finished film are aligned, the lithography machine is started to perform secondary exposure according to the adjusted exposure parameters. During the exposure process, ultraviolet light passes through the transparent part of the finished film and irradiates the photoresist on the first flexible circuit board, triggering further chemical reactions of the photoresist to obtain the first flexible circuit board after secondary exposure.

[0111] Step 1064: Perform secondary development on the first flexible circuit board after secondary exposure to obtain the first flexible circuit board after secondary development;

[0112] Specifically, the development process in this step can be the same as that of the primary development.

[0113] Step 1065: Perform cleaning and drying on the first flexible circuit board after secondary development to obtain the second flexible circuit board.

[0114] Specifically, a cleaning agent such as deionized water can be used to clean the first flexible circuit board after secondary development to remove the residual developer and photoresist residues. Then, the cleaned first flexible circuit board is dried with nitrogen or placed in a drying oven for drying to avoid the influence of moisture on the circuit pattern.

[0115] In an alternative embodiment of the present invention, step 107 includes:

[0116] Step 1071: Provide an etching solution;

[0117] Specifically, the etching solution can be a copper chloride solution or a sulfamic acid solution, etc. Or other types of etching solutions can be selected according to the material and etching requirements of the second flexible circuit board.

[0118] Step 1072: Determine the etching parameters according to the etching solution;

[0119] Specifically, the etching parameters generally include etching temperature (between room temperature and 60°C), etching time, etching rate, solution concentration, and stirring method (mechanical stirring or gas stirring), etc. Among them, the etching temperature is usually set according to the type and concentration of the etching solution, generally between room temperature and 60°C. A higher temperature can accelerate the etching rate, but it may also affect the etching uniformity and accuracy, which needs to be determined according to the actual process flow; the etching time needs to be determined according to the complexity of the circuit pattern, the thickness of the copper layer, and the etching rate of the etching solution, and can be adjusted according to the situation during the etching process, and can be set from 5 seconds to 8 minutes; the etching rate refers to the thickness of the copper layer etched per unit time, usually in micrometers per minute. The etching rate is affected by various factors such as the concentration, temperature, stirring degree of the etching solution, and the surface state of the copper layer, and can be set from 30 to 500 micrometers per minute; the concentration of the etching solution directly affects the etching rate and etching quality. Too high a concentration may cause over-etching and side-etching problems, while too low a concentration may result in incomplete etching. Therefore, it needs to be adjusted according to specific process requirements and can be set from 60 to 300 g / L; during the etching process, it should be ensured that the etching solution flows evenly to promote the etching reaction. The stirring method can be mechanical stirring or gas stirring, etc.

[0120] Here, it is assumed that a copper layer with a thickness of 35 μm (the copper layer on the second flexible circuit board) is etched using a copper chloride solution to form a circuit pattern with a width of 0.1 mm. Then the etching parameters can be set as follows: the concentration of the etching solution is 50 g / L, the temperature of the etching solution is 40°C, the etching rate is 1 μm / min, and the etching time is 35 minutes.

[0121] Step 1073, according to the etching parameters, place the second flexible circuit board into an etching device for etching treatment to obtain the etched second flexible circuit board;

[0122] Specifically, input the etching parameters into the controller of the etching machine, place the second flexible circuit board into the etching machine, and the etching machine performs etching operations on the second flexible circuit board according to the set etching parameters. During the etching process, the etching effect should be closely observed, and the etching parameters should be appropriately adjusted as needed to improve the accuracy of the circuit pattern.

[0123] Step 1074, perform a degumming treatment on the second flexible circuit board to obtain the target flexible circuit board.

[0124] Specifically, the second flexible circuit board can be rinsed with clean water to remove residual etching solution and photoresist, etc. Here, the rinsed second flexible circuit board can also be dried to obtain the target flexible circuit board.

[0125] In an alternative embodiment of the present invention, the method further includes:

[0126] Step 108: Conduct an appearance inspection on the target flexible circuit board to obtain an appearance inspection result;

[0127] Specifically, it is possible to check whether there are scratches, impurities, damages, etc. on the surface of the target flexible circuit board. The appearance inspection result includes the inspection situation of the surface of the target flexible circuit board. Here, a magnifying glass, a strong flashlight, etc. can be used to clearly observe the details of the surface of the target flexible circuit board. The specific methods of appearance inspection can include:

[0128] Place the target flexible circuit board on a flat workbench, and use a magnifying glass to carefully observe the etched cross pattern (if any), and check whether the lines of the cross are clear and continuous, without breakage or blurring. At the same time, confirm whether the position of the cross is accurate and consistent with the requirements in the preset circuit pattern. Use a strong flashlight to irradiate from one side of the target flexible circuit board, and observe the positioning holes on the other side. Check whether the shape and size of the positioning holes meet the requirements of the preset circuit pattern, whether the edges are smooth, without burrs or cracks, and at the same time, confirm whether the position of the positioning holes is accurate and the relative position relationship with the cross pattern and other marks is correct.

[0129] Step 109: Conduct a circuit pattern inspection on the target flexible circuit board to obtain a circuit pattern inspection result;

[0130] Specifically, a microscope can be used to check the integrity of the circuit patterns on the target flexible circuit board and measure parameters such as line width and line pitch. The circuit pattern inspection result can include the inspection situation of the circuit patterns on the target flexible circuit board. Here, the surface of the target flexible circuit board can be scanned comprehensively to check the integrity of all circuit patterns, and confirm whether the circuit patterns are continuous, without open circuits or short circuits. At the same time, check whether the thickness, pitch, etc. of the circuit patterns meet the requirements of the preset circuit pattern, and whether the position of the circuit patterns is accurate.

[0131] Step 1010: Screen the target flexible circuit board according to the appearance inspection result, the circuit pattern inspection result and the preset qualified conditions to obtain a qualified target flexible circuit board.

[0132] Specifically, the preset qualified conditions include: there are no scratches, impurities, damages, etc. on the surface of the flexible circuit board, the integrity of the circuit patterns, the line width meets the preset line width, and the line pitch meets the preset line pitch, etc. If both the appearance inspection result and the circuit pattern inspection result meet the preset qualified conditions, the corresponding target flexible circuit board is a qualified target flexible circuit board, which can be packaged and sent to the customer. This is beneficial to improving customer satisfaction and is also beneficial to repairing the target flexible circuit board according to the inspection situation to improve the product qualification rate.

[0133] A specific embodiment of the method for processing a flexible circuit board proposed in the embodiment of the present invention is:

[0134] Step 111, obtain a flexible circuit board substrate and an original film.

[0135] Provide a flexible circuit board substrate of corresponding material according to user requirements and the design requirements of the flexible circuit board. Obtain a suitable original film according to the actual situation.

[0136] It should be noted that the flexible circuit board substrate in this embodiment may already have a copper layer (the circuit can be etched), and all the process flows before exposure may have been carried out. This application only specifically describes the process flows involved in the embodiment. Those skilled in the art can combine the process flows in this application with other processes to manufacture flexible circuit boards, which will not be elaborated in this application.

[0137] Step 112, determine the layout data.

[0138] According to the drawing of the circuit pattern provided by the user, obtain the user's accuracy requirements for the circuit pattern. If it meets the preset accuracy information, then select the subsequent secondary exposure process. At this time, it is necessary to determine the layout data in the graphic design software according to the preset layout conditions.

[0139] Step 113, manufacture the finished film.

[0140] After inspecting and adjusting the layout data, use a laser imagesetter to manufacture a film with a circuit image. Then use a punch to punch holes in the film. After passing the inspection, obtain the finished film.

[0141] Step 114, pre-treat the flexible circuit board substrate.

[0142] Pre-treat the flexible circuit board substrate, such as cleaning, micro-etching, and anti-oxidation, to increase the surface roughness and activity of the flexible circuit board substrate, making it easier to combine with materials (such as photoresist) in subsequent processes.

[0143] Step 115, first exposure.

[0144] Coat photoresist on the flexible circuit board substrate, then bake it. After that, according to the first preset exposure parameters, put the baked flexible circuit board substrate and the finished film into the exposure equipment for a first exposure process and a first development process to obtain a first flexible circuit board.

[0145] Step 116, second exposure.

[0146] According to the result of the first exposure, adjust the first preset exposure parameters to obtain the second preset exposure parameters. Perform a second exposure on the first flexible circuit board according to the second preset exposure parameters to form finer pattern features and improve the accuracy of the circuit pattern.

[0147] Step 117, etching process.

[0148] Etch the second flexible circuit board using an etching machine according to the determined etching parameters to obtain a target flexible circuit board. Then, perform appearance and line inspections on the target flexible circuit board to obtain a qualified flexible circuit board.

[0149] The method for processing a flexible circuit board according to an embodiment of the present invention uses double exposure to fabricate a circuit pattern on the flexible circuit board, reducing the steps and time in the production process, improving the accuracy of the circuit pattern, and at the same time, enhancing customer satisfaction.

[0150] An embodiment of the present invention also provides a flexible circuit board fabricated by using the method for processing a flexible circuit board according to any one of the above embodiments.

[0151] During the fabrication process of the flexible circuit board according to an embodiment of the present invention by using the method for processing a flexible circuit board according to any one of the above embodiments, after the first exposure, a pattern corresponding to the finished film will be formed on the photoresist. Subsequently, without moving the flexible circuit board, the same finished film (in other embodiments, different finished films can also be used according to actual requirements) is used for the second exposure. The superposition of the light intensities of these two exposures will produce different exposure effects on the photoresist, thereby forming a more complex pattern. The following is a specific embodiment for illustration:

[0152] There is a simple line pattern on the finished film, with a line width of 100 microns and a line spacing of 100 microns. Using appropriate light intensity (exposure energy) and exposure time (first preset exposure parameters), the flexible circuit board is subjected to the first exposure. After the exposure, a line pattern corresponding to the finished film will be formed on the photoresist of the flexible circuit board, but the width and spacing of the lines may vary due to the exposure conditions. Without moving the flexible circuit board, the same finished film is used for the second exposure. The light intensity (exposure energy) and exposure time (second preset exposure parameters) of the second exposure can be different from those of the first exposure to produce different exposure effects. For example, the second exposure can use a weaker light intensity and a longer exposure time to form a wider exposed area around the lines of the first exposure.

[0153] After two exposures, a more complex pattern will be formed on the photoresist of the flexible circuit board. The line pattern of the first exposure may be surrounded by the wide exposed area of the second exposure, forming a pattern similar to a "frame". Or, if the light intensity and time of the second exposure are properly controlled, additional lines or pattern elements can also be formed between the lines of the first exposure.

[0154] It should be noted that, according to actual requirements, by adjusting the first preset exposure parameter and / or the second preset exposure parameter, as well as the type of photoresist, etc., the circuit pattern after the second exposure can be made deeper or more obvious than the pattern after the first exposure. Or, on the basis of the first exposure, a new pattern or structure can be formed on the existing circuit pattern through the second exposure (that is, only a part or the basic structure of the circuit pattern is formed during the first exposure, such as Figure 2 part of the circuit pattern 11 in Figure 3 ; while the second exposure is responsible for adding or modifying the remaining part, such as

[0155] in

[0156] where the complete circuit pattern is composed of part of the circuit pattern 11 and the remaining circuit pattern 12), so as to improve the accuracy of the final circuit pattern on the flexible circuit board.

[0157] It should be noted that in the devices and methods of the present invention, obviously each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations shall be regarded as equivalent solutions of the present invention. And, the steps of performing the above series of processes can naturally be executed in chronological order according to the described order, but it is not necessary to be executed in chronological order. Certain steps can be executed in parallel, crosswise or independently of each other.

[0158] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A processing method for a flexible circuit board, characterized in that, including: obtaining a flexible circuit board substrate and an original film; determining layout data; obtaining a finished film according to the layout data and the original film; preprocessing the flexible circuit board substrate to obtain a preprocessed flexible circuit board substrate; obtaining a first flexible circuit board according to the preprocessed flexible circuit board substrate and the finished film; obtaining a second flexible circuit board according to the first flexible circuit board and the finished film; etching the second flexible circuit board to obtain a target flexible circuit board; wherein, determining the layout data includes: obtaining accuracy information of a circuit pattern; when the accuracy information of the circuit pattern meets the preset accuracy information, determining layout data according to preset layout conditions, the flexible circuit board substrate and the original film; the preset accuracy information is that the circuit pattern is flush with the outer edge of the flexible circuit board or the accuracy is greater than 90%; wherein, obtaining the first flexible circuit board according to the preprocessed flexible circuit board substrate and the finished film includes: putting the preprocessed flexible circuit board substrate into a coating device according to preset coating parameters for photoresist coating to obtain a flexible circuit board substrate with photoresist; putting the flexible circuit board substrate with photoresist into a baking device according to preset baking parameters for baking to obtain a baked flexible circuit board substrate; performing a first exposure process on the baked flexible circuit board substrate and the finished film in an exposure device according to first preset exposure parameters to obtain a once-exposed flexible circuit board substrate; performing a first development process on the once-exposed flexible circuit board substrate to obtain a first flexible circuit board; wherein, obtaining the second flexible circuit board according to the first flexible circuit board and the finished film includes: adjusting the first preset exposure parameters according to the first flexible circuit board to obtain second preset exposure parameters; wherein, by checking whether the exposure result of the first flexible circuit board is uniform and whether there are unexposed or overexposed areas, adjusting the first preset exposure parameters, and taking the increased / decreased exposure energy and the shortened / extended exposure time as the second preset exposure parameters; aligning the first flexible circuit board and the finished film to obtain an aligned first flexible circuit board and finished film; wherein, the patterns between the finished film and the first flexible circuit board are completely matched; performing a second exposure process on the aligned first flexible circuit board and finished film to obtain a second-exposed first flexible circuit board; performing a second development process on the second-exposed first flexible circuit board to obtain a second-developed first flexible circuit board; performing a cleaning and drying process on the second-developed first flexible circuit board to obtain a second flexible circuit board.

2. The processing method of the flexible circuit board according to claim 1, wherein Determining the layout data according to preset layout conditions, the flexible circuit board substrate and the original film includes: obtaining original layout data according to preset layout conditions, the flexible circuit board substrate and the original film; performing format conversion on the original layout data according to a preset format to obtain layout data.

3. The processing method of the flexible circuit board according to claim 1, wherein Obtain a finished film according to the typesetting data and the original film, including: Perform image exposure on the original film to obtain a first film; Perform punching on the first film according to the typesetting data to obtain a second film; Inspect the second film. If the inspection result meets the preset inspection conditions, the second film is the finished film.

4. The processing method of the flexible circuit board according to claim 1, wherein, Perform pretreatment on the flexible circuit board substrate to obtain a pretreated flexible circuit board substrate, including: Clean the flexible circuit board substrate to obtain a cleaned flexible circuit board substrate; Perform surface micro-etching on the cleaned flexible circuit board substrate to obtain a micro-etched flexible circuit board substrate; Perform anti-oxidation treatment on the micro-etched flexible circuit board substrate to obtain a pretreated flexible circuit board substrate.

5. The processing method of the flexible circuit board according to claim 1, characterized in that, Perform etching on the second flexible circuit board to obtain a target flexible circuit board, including: Provide an etching solution; Determine etching parameters according to the etching solution; Put the second flexible circuit board into an etching device for etching according to the etching parameters to obtain an etched second flexible circuit board; Perform degumming on the second flexible circuit board to obtain a target flexible circuit board.

6. The processing method of the flexible circuit board according to claim 1, characterized in that, It also includes: Perform an appearance inspection on the target flexible circuit board to obtain an appearance inspection result; Perform a circuit pattern inspection on the target flexible circuit board to obtain a circuit pattern inspection result; Screen the target flexible circuit board according to the appearance inspection result, the circuit pattern inspection result and the preset qualified conditions to obtain a qualified target flexible circuit board.

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