A processing technology of FPC circuit board applied to a rocker game handle

Abstract

The application provides an FPC circuit board processing technology applied to a joystick of a gamepad, and comprises the following steps: adopting a copper foil material of calendered copper to perform cutting to obtain a substrate of the FPC circuit board; performing RTR dry film lamination or RTR wet dry film lamination on the substrate; performing RTR circuit exposure on the substrate after the RTR dry film lamination, and then completing the production of the circuit through RTR etching technology; adopting a carbon paste process to perform product design; adopting a silk screen mesh selection technology to perform printing on a printed board circuit pattern; adopting a thermosetting ink matching technology and a thermosetting ink printing technology to complete the printing requirement of FPC board ink, and finally obtaining the FPC circuit board which meets the requirements of the resistance value of 5±1KΩ and the printing thickness of 20±2um of the ink; and the PSPI ink coating is used to replace the cover film to improve the step difference and voltage offset, so that the requirements of the resistance value and hardness of the FPC flat type direction potentiometer of the current gamepad joystick are met.

Description

Technical Field

[0001] The present invention relates to a processing technology for a flexible printed circuit board (FPC), and in particular to a processing technology for an FPC circuit board used in a joystick game console controller. Background Art

[0002] Flexible printed circuits (FPCs) offer advantages such as high wiring density, ultra-thinness, ultra-lightness, foldability, and high assembly flexibility. They can be freely moved and extended within the main body space, facilitating the integration of component assembly and wire connection. Currently, FPCs are used in nearly all electronic information products, including consumer electronics, communications equipment, and automotive products. Multilayer FPCs, in particular, offer the advantages of conventional single- or double-sided FPCs, such as foldability and high assembly flexibility, while also possessing the load-bearing capacity of rigid printed circuit boards (PCBs). This allows them to replace some traditional rigid PCBs and expand their application areas.

[0003] With the continuous progress and development of society, computers have become widely popularized and applied. The corresponding game controller can conveniently and quickly realize the operation of computer games, and has become one of the increasingly popular components in computer equipment. By operating its buttons, etc., the simulated character on the computer can be controlled. This involves an FPC flat direction potentiometer in the game joystick technology.

[0004] The FPC flat directional potentiometer for game controller joysticks requires a resistance within the range of (5±1) kΩ and a friction resistance of 1 million times. Therefore, this product has very high requirements for both resistance and hardness. However, current FPC circuit board processing technology struggles to meet these requirements. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to provide an FPC circuit board processing technology applied to joystick game console handles to meet the current game controller joysticks' requirements on resistance and hardness (friction resistance) for such FPC flat directional potentiometers.

[0006] To achieve the aforementioned purpose of the invention, the technical solution adopted by the embodiment of the present invention is: a FPC circuit board processing process applied to a joystick game controller, comprising the following steps:

[0007] S1. Cut the copper foil of rolled copper to obtain the substrate of FPC circuit board;

[0008] S2. Perform RTR dry film lamination or RTR wet press dry film lamination on the substrate;

[0009] S3, perform RTR circuit exposure on the substrate after RTR dry film bonding, and then complete the circuit production through RTR etching technology;

[0010] S4. Use carbon slurry technology for product design;

[0011] S5. Use silk screen frame selection technology to print printed circuit graphics;

[0012] S6. Use thermosetting ink blending technology and thermosetting ink printing technology to complete the printing requirements of the FPC board ink, and finally produce an FPC circuit board that meets the requirements of ink resistance of 5±1KΩ and printing thickness of 20±2um;

[0013] S7. PSPI ink coating is used to replace the cover film to improve the step difference and voltage deviation.

[0014] Furthermore, in step S2, the RTR dry film lamination is to first use a PET with a length greater than 1 meter to stick double-sided tape on the copper area of ​​the product and quickly press it flat;

[0015] The RTR wet-press-dry film lamination refers to loading the material with the copper side facing upwards, then laminating and pressing the film using a wet method, and then rewinding the material with the copper side facing inwards.

[0016] Furthermore, in step S3, the RTR line exposure is performed using RTR fully automatic exposure equipment;

[0017] The production of the circuit refers to the use of advanced precision vacuum etching technology. The etching section uses the AQUA control system and related equipment to accurately control the fluctuation range of the concentration of chemical solutions used in the etching process within the required range. Other solution sections use a precise automatic solution addition system. The equipment automatically accumulates and calculates the product production volume and automatically adds solutions according to the set addition value.

[0018] Furthermore, step S4 specifically includes: appropriately increasing the carbon ink area according to the actual printing results to prevent the carbon ink effective width W from being reduced or the effective length L from being deviated due to the screen printing offset, resulting in the carbon resistor opening. The area S of the screen-printed carbon ink block is designed to completely cover the entire carbon bridge contact point and the connecting copper foil; and the design of the effective width W and the effective length L satisfy Ohm's law:

[0019] R=Rp×WL / S, Rp=5±1KΩ.

[0020] Furthermore, in the screen printing frame selection technology of step S5, the screen mesh size is selected based on the calculation result of the following relationship plus a margin of 30-50%, and the relationship is:

[0021] D ≥ 2s + K, M = 1 / (Ds);

[0022] Where: D is the thinnest line width or the smallest dot diameter that can be printed; s is the line diameter; K is the aperture; M is the mesh count of the screen.

[0023] Furthermore, the thermosetting ink preparation technology in step S6 uses conductive carbon paste to add to thermosetting ink to prepare a composite carbon paste ink; the composite carbon paste ink must be sealed and stored in a low-temperature, dry environment when not in use. It must be taken out of the low-temperature environment at least 4 hours before each use and allowed to return to room temperature before use. The carbon conductive ink must be fully stirred before use, and no diluent should be added.

[0024] Furthermore, the solid ink printing technology in step S6 should control the following parameters in actual operation: the screen height is selected to be 2 mm; and the scraping angle is selected to be between 30 and 70 degrees.

[0025] The advantage of this invention lies in: based on the specific characteristics of the FPC circuit board manufacturing process for joystick game controllers, the project optimizes and innovates the existing company's processing process to comply with the IPC-6013 "Quality Requirements and Performance Specification for Flexible Printed Circuits" established by the International Electronics Industry Association (IPC). This meets the current requirements for resistance and hardness (friction resistance) of FPC flat directional potentiometers used in joystick game controllers. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] Figure 1 This is a schematic diagram of the current common FPC circuit board processing process;

[0028] Figure 2 This is a process flow chart for processing the FPC circuit board of the joystick game controller of the present invention;

[0029] Figure 3 This is a schematic diagram of the circuit film design of an embodiment of the product design of the present invention. DETAILED DESCRIPTION

[0030] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0031] The technical solution adopted in the embodiment of the present invention is: a FPC circuit board processing process applied to a joystick game controller, comprising the following steps:

[0032] S1. Cut the copper foil of rolled copper to obtain the substrate of FPC circuit board;

[0033] S2. Perform RTR dry film lamination or RTR wet press dry film lamination on the substrate;

[0034] S3, perform RTR circuit exposure on the substrate after RTR dry film bonding, and then complete the circuit production through RTR etching technology;

[0035] S4. Use carbon slurry technology for product design;

[0036] S5. Use silk screen frame selection technology to print printed circuit graphics;

[0037] S6. Use thermosetting ink blending technology and thermosetting ink printing technology to complete the printing requirements of the FPC board ink, and finally produce an FPC circuit board that meets the requirements of ink resistance of 5±1KΩ and printing thickness of 20±2um;

[0038] S7. PSPI ink coating is used to replace the cover film to improve the step difference and voltage deviation.

[0039] For more detailed and complete process, please see Figure 2 shown.

[0040] Furthermore, as a better or more specific implementation of the present invention, the FPC circuit board processing technology used in joystick game console controllers is mainly studied, as follows:

[0041] (1) In step S2, the RTR dry film lamination refers to first using a PET with a length greater than 1 meter to stick double-sided tape on the copper area of ​​the product and then pressing it flat;

[0042] The RTR wet-press-dry film lamination refers to loading the material with the copper side facing upwards, then laminating and pressing the film using a wet method, and then rewinding the material with the copper side facing inwards.

[0043] This invention utilizes multi-RTR dry film lamination technology. During the circuit board manufacturing process, pre-treatment is required to clean and roughen the copper surface to avoid affecting subsequent manufacturing processes. Conventional products do not require special surface pre-treatment. This single-sided board is an ultra-thin product, and pre-treatment with the equipment may result in poor imprinting and carding. The product also has a relatively large exposed copper area, requiring certain copper surface thickness, which is affected by micro-etching. To address this, the copper area of ​​the product must first be taped with double-sided tape using PET (PET length > 1 meter) and then pressed flat.

[0044] This invention utilizes RTR (Wet-Tap Dry Film Lamination) technology. Because copper foil surfaces can be subject to surface defects such as unevenness, pinholes, dents, and scratches, which can create interfacial voids and lead to defects such as notches and open circuits during etching, wet lamination creates a water film on the copper foil surface. This increases the dry film's fluidity under pressure and reduces its viscosity, thereby enhancing its filling efficiency. The material is loaded copper-side up during wet lamination. After lamination, the material must be rewound copper-side inward. Verification and testing have shown that this parameter results in a smooth, wrinkle-free film surface, significantly improving adhesion between the dry film and the substrate, and enhancing circuit processing quality.

[0045] (2) In step S3, the RTR circuit exposure is performed using an RTR fully automatic exposure device. The present invention uses an RTR fully automatic exposure device to reduce the wrinkling of thin single-sided boards. Accurate alignment and exposure energy are factors that require special attention in the exposure process. When the exposure is insufficient, due to incomplete polymerization of the monomer, the film swells and softens during the development process, the lines are unclear, the color is dull, and even debonding occurs. When the exposure is excessive, it will cause problems such as difficulty in development, brittleness of the film, and residual adhesive. More seriously, incorrect exposure energy will cause deviations in the image line width. Excessive exposure will make the etched lines thicker, and insufficient exposure will make the etched lines thinner. The use of RTR fully automatic exposure equipment can effectively meet the requirements of single-sided copper thinning and circuit precise exposure.

[0046] The production of the circuit refers to the use of advanced precision vacuum etching technology. The etching section uses the AQUA control system and related equipment to accurately control the fluctuation range of the concentration of chemical solutions used in the etching process within the required range. Other solution sections use a precise automatic solution addition system. The equipment automatically accumulates and calculates the product production volume and automatically adds solutions according to the set addition value.

[0047] The application adopts advanced precise vacuum etching technology, and the concentration content fluctuation range of chemical products (HCl, NaClO3 and CuCl2) used in etching process is accurately controlled within the required range by AQUA control system related equipment in the etching section, and other chemical products such as developing and demolding are added by precise automatic adding chemical product system, the device automatically accumulates and automatically calculates the product production, and automatically adds the chemical product according to the set adding value without manual intervention, the fluctuation range of the chemical product is effectively controlled, the chemical product is stably controlled within the controllable range of process parameters, and the prerequisite requirements of precise circuit etching processing are basically met. The etching technology is challenging, especially when producing precise wire products, the line width tolerance requirement is very strict, therefore, the line effect after etching needs to be consistent as much as possible. In the conventional DES horizontal conveying line production, the pool effect will cause the etching factor of the central part of the plate to be poorer than that of the edge part of the plate, which leads to the line width deviation seriously exceeding the product tolerance requirement. In addition, in the production, the horizontal conveying wheel hinders the discharge of the etching liquid, and the etching liquid is stored between the wheels, so the pool effect cannot be avoided. The project adopts advanced vacuum etching process technology, the used etching liquid can be sucked by installing a water pump in the etching section, the flowability of the etching liquid on the upward plate surface can be effectively improved, and the generation of the pool effect is prevented. This method is called vacuum etching. After adopting the vacuum etching technology, under the condition of adjusting and controlling the etching process, the vacuum etching process can achieve excellent effect. After vacuum etching, the etching effect on the entire surface of the double sides of the substrate is very uniform. The line width tolerance requirement of the project is ±5μm, therefore, the DES line needs to meet the requirement that the etching uniformity is >=95%, and on the basis of the equipment with vacuum etching technology, the parameters such as spraying pressure, chemical product concentration, chemical product temperature and etching speed need to be optimized and tested.

[0048] (3) The step S4 is specifically: appropriately increasing the carbon oil area according to the actual printing result, preventing the carbon resistance from being opened due to the decrease of the effective width W of the carbon oil or the deviation of the effective length L of the carbon oil, and the design of the square area S of the silk-screened carbon oil is based on covering the entire carbon bridge contact point and the connected copper sheet; and the design of the decrease of the effective width W and the effective length L meets the Ohm's law: R=Rp x WL / S, Rp=5±1KΩ.

[0049] The application needs to meet the resistance value requirement, and adopts the carbon paste process, and the design needs to meet the correction.

[0050] Since a large part of the carbon oil is resin, and the resin itself is brittle, when designing the carbon oil for such products, it is necessary to increase the contact area of the carbon oil area and the metal surface, but the performance requirements of the products also need to be considered, for which Figure 3The figure below shows the circuit film design. Based on the actual printing results, the carbon ink area is appropriately increased to prevent screen printing deviations from reducing the effective width of W or L from causing an open circuit. The screen-printed carbon ink square is designed to fully cover the entire "upper" carbon bridge contact point and the connecting copper foil. The design of "L" and "W" is primarily based on the theoretical design values ​​calculated based on the resistance value of (5±1) kΩ and Ohm's law (R=Rp×WL / S).

[0051] (4) In the screen printing frame selection technology of step S5, the screen mesh size is selected based on the calculation result of the following relationship plus a margin of 30-50%, and the relationship is:

[0052] D ≥ 2s + K, M = 1 / (Ds);

[0053] Where: D is the thinnest line width or the smallest dot diameter that can be printed; s is the line diameter; K is the aperture; M is the mesh count of the screen.

[0054] Screen printing is a method of transferring an image by transferring ink onto a substrate through a screen. The selection of a screen frame is crucial for screen printing. The screen frame is a support that holds and supports the screen, and together with the screen, it forms the screen. Screen specifications primarily include mesh count, aperture, wire diameter, screen thickness, and mesh area ratio. Mesh count refers to the number of mesh openings per unit area and generally indicates the density of the meshes. A higher mesh count indicates a denser screen and smaller mesh openings. Conversely, a lower mesh count indicates a more coarse screen and larger mesh openings. Smaller mesh openings reduce ink permeability, while larger mesh openings improve ink permeability. Screen selection can be tailored to the desired printing precision. The following formula can be used to select a screen with the appropriate mesh size. For printed circuit board (PCB) graphics requiring high precision, a 30-50% margin should be added to the mesh size calculated using the following formula.

[0055] Screen thickness refers to the distance between the top and bottom surfaces of the screen, typically measured in millimeters (mm) or micrometers (μm). The thickness should be measured when the screen is at rest, tension-free. The thickness is determined by the diameter of the screen.

[0056] This product has a wear-resistance requirement, requiring an ink thickness of 20 ± 2 μm. Thicker ink thickness improves hardness. The screen, in turn, influences the selection of screen type, mesh size, and slurry thickness; this essentially determines the volume of carbon ink required for printing. The finer the mesh size and the thicker the slurry thickness, the greater the volume of carbon ink required for screen printing. This translates directly to lower carbon ink resistance and reduced drying during baking. Therefore, choosing the right screen is a crucial factor influencing carbon ink thickness. A steel screen with a mesh size of 250 and an emulsion thickness of 25 μm was selected. DOE validation of the processing parameters confirmed that they met the process requirements for this product.

[0057] (5) The thermosetting ink preparation technology of step S6 adopts the method of adding conductive carbon paste into thermosetting ink to prepare composite carbon paste ink; the composite carbon paste ink must be sealed and stored in a low-temperature dry environment when not in use. It must be taken out from the low-temperature environment at least 4 hours in advance before each use and allowed to return to room temperature before use. The carbon conductive ink must be fully stirred before use, and no diluent should be added.

[0058] The present invention adopts thermosetting ink mixing technology, and the thermosetting ink selected this time is conductive carbon paste.

[0059] Due to its high mechanical strength, wear resistance, and excellent conductivity, carbon conductive ink can replace the nickel-gold plating on plugs or keyboards and is suitable for use in electromechanical keyboards, computer keyboard switch plugs, and single- and double-sided printed circuit board keyboards. Composite carbon paste ink is a thermosetting conductive ink. After curing, the ink protects the copper foil and conducts current, exhibiting excellent conductivity. The ink film is not easily oxidized and has stable performance. After curing, it is resistant to corrosion by acids, alkalis, and chemical solvents. The ink has strong adhesion and peel resistance, and bonds well with copper foil or glass cloth. However, due to the significant difference in the chemical activity of carbon and conductor materials (such as copper), if the two are exposed to a humid atmosphere, electrochemical corrosion at the connection will affect the service life of the equipment, limiting the use of such products. Therefore, for products with strict requirements, the conductive carbon ink is printed after the solder mask layer is printed to protect the conductive carbon ink layer.

[0060] Furthermore, conductive inks must be sealed and stored in a cool, dry environment when not in use. They must be removed from the cold environment at least 4 hours before each use and allowed to return to room temperature. Carbon conductive inks must be thoroughly stirred before use. Because carbon powder has a higher specific gravity, some precipitation will occur during storage. Furthermore, compared to conventional circuit printing materials, carbon conductive inks are more thixotropic, so stirring reduces their tactility, increasing their viscosity. Avoid adding diluents during use.

[0061] When it comes to selecting the appropriate resistance value, not every type of carbon ink is available. Essentially, only a few standard square resistors are available. Single-component carbon inks can be used directly within the resistance range of (5±1) kΩ. However, actual customer requirements may fall between the two standard resistors, necessitating the mixing of high- and low-resistance carbon inks in varying ratios. By testing various high- and low-resistance ink ratios, we verify that the ink resistance meets the requirements. Currently, the required resistance value of (5±1) kΩ is achieved while also meeting the required thickness. The main challenge lies in the ink mixing ratio, which must meet both the resistance value requirements and the required thickness and viscosity.

[0062] (6) The solid ink printing technology of step S6 should control the following parameters in actual operation: the screen height is selected to be 2 mm; the scraping angle is selected to be between 30 and 70 degrees.

[0063] Thermosetting ink printing technology is used, and the thermosetting ink printing technology is screen printing. Screen printing is an image transfer method that uses a silk screen to leak ink onto the substrate.

[0064] To achieve good printing results, the following parameters should be controlled in actual operation, provided that the screen is intact, the ink is appropriate, and the positioning is correct:

[0065] Stencil height refers to the distance between the printing screen and the substrate being printed on the workbench. This distance ensures that the substrate and screen are not in contact when not printing, preventing ink from adhering to the substrate. During printing, the squeegee presses down on the screen, creating a moving line of contact between the screen and the substrate. After the squeegee is applied, the screen should immediately bounce off the substrate, otherwise ink bleeds and blurs the image. Therefore, a suitable stencil height is crucial. Factors determining stencil height include screen size and screen tension, and a typical setting is around 2mm.

[0066] The scraper angle, also known as the scraping angle, refers to the angle between the scraper and the printed substrate during printing. The scraping angle significantly affects ink transfer and printed image accuracy. Relatively speaking, a larger scraping angle reduces ink leakage, while a smaller scraping angle increases ink leakage. The scraping angle is determined by scraper hardness and pressure, and is typically between 30° and 70°.

[0067] Squeegee pressure refers to the pressure the squeegee maintains on the printed surface during printing. The screen only contacts the substrate at this pressure, maintaining linear contact. When the pressure is too low, the screen loses contact with the substrate, preventing the image from being printed. When the pressure is too high, the screen contacts the substrate in a surface-to-surface manner, leading to excessive ink leakage, blurred images, and wear on the screen.

[0068] Squeegee speed refers to the speed at which the squeegee moves during printing. Squeegee speed significantly affects the amount and uniformity of ink transferred. If the squeegee moves too fast, insufficient ink will leak, resulting in image defects. If the squeegee moves too slowly, excessive ink will leak, causing blurred images. Therefore, maintaining an appropriate speed while maintaining a constant speed is crucial.

[0069] Whether printing by hand or by machine, the above parameters must be considered. Manual printing relies primarily on the operator's skill. Machine printing allows for mechanical adjustments to achieve ideal conditions.

[0070] In the actual production process, in addition to the screen, printing process parameters and equipment are also important factors affecting the printing effect. Changes in any of the printing process parameters, such as the screen printing machine's precision and automation level, squeegee hardness, squeegee angle, squeegee flatness, screen printing pressure, screen printing speed, and screen height, will affect the thickness of the carbon ink. In actual work, the printing process parameters must be determined based on the actual product type and resistance requirements through sample, small batch, and large batch verification. These parameters should be clearly defined and adjusted according to the specifications for each print run to ensure the resistance stability of the carbon ink product.

[0071] Semi-automatic printing machines typically use patch pins for positioning. These thin stainless steel sheets with protruding pins on one side are attached to the printing surface with two or three of these pins fixed to the printing surface. This positioning method offers good accuracy. However, testing has shown significant variations in uniformity when printing with ink on these products. Printed patterns can be thicker on one side and thinner on the other, and can also exhibit misalignment. Fully automatic printing machines use CCD recognition, which uses image recognition to identify mark points for positioning. This method offers high accuracy, and testing has shown excellent ink thickness uniformity in products printed with this equipment. Adjusting the ink thickness can effectively mitigate issues where the same pin has some good and some bad resistance values.

[0072] Based on the above verification, this project uses a fully automatic CCD screen printer and adjusts parameters such as squeegee angle, squeegee hardness, squeegee angle, squeegee flatness, screen printing pressure, screen printing speed, and screen height. The printed ink thickness meets 20±2μm and the resistance meets (5±1)KΩ.

[0073] Finally, there is another part that needs attention. For carbon oil products with strict resistance requirements, friction on the carbon oil surface is not allowed. The carbon oil is not allowed to be exposed to the air and must be covered under the solder mask. In addition, if there is a surface treatment process after printing the carbon oil, it will have a certain impact on the resistance of the carbon oil. This requires adjustment of the carbon oil design or the thickness of the carbon oil based on the actual product process design and the requirements for product resistance. This part involves more aspects and can only be summarized in actual mass production experience.

[0074] (7) Surface step difference control technology. This invention uses surface step difference control technology. The products produced in the early stage all had step difference problems and voltage deviation. Slice analysis showed that the problem was caused by uneven ink thickness. For some products, PSPI ink coating was used to replace the cover film.

[0075] Polyimide (PSPI) is a type of organic material that combines imide rings and photosensitive groups within its polymer chain, exhibiting excellent thermal stability, mechanical properties, chemical properties, and photosensitivity. Based on its structural characteristics, preparation method, and photosensitivity, PSPI can be categorized into various types, including ionic negative PSPI, self-sensitizing negative PSPI, negative ester PSPI, polyisoimide positive PSPI, and o-nitrobenzyl ester positive PSPI. The three types of PSPI currently in industrial production each have their own advantages and disadvantages. Ester PSPI offers excellent solubility and film-forming properties, but suffers from a lower polymer molecular weight. Ionic PSPI offers a convenient and economical manufacturing process, but suffers from a lower film retention rate. Self-sensitizing PSPI has a relatively high film retention rate, but suffers from lower resolution and higher raw material costs. This application utilizes a PSPI ink coating instead of a cover film, reducing the gap between the two ink layers. Furthermore, because the ink layer is thinner than the cover film, the PSPI process can mitigate the step difference issue. Using PSPI instead of cover film can effectively improve the problem of step difference.

[0076] Through the above solution, the problems of product step difference and voltage deviation are effectively improved, and the product resistance value (5±1) KΩ and the friction resistance requirement of 1 million times are met.

[0077] The advantage of this invention lies in: based on the specific characteristics of the FPC circuit board manufacturing process for joystick game controllers, the project optimizes and innovates the existing company's processing process to comply with the IPC-6013 "Quality Requirements and Performance Specification for Flexible Printed Circuits" established by the International Electronics Industry Association (IPC). This meets the current requirements for resistance and hardness (friction resistance) of FPC flat directional potentiometers used in joystick game controllers.

[0078] While the foregoing description has described specific embodiments of the application, one ordinary skill in the art will appreciate that various modifications and changes can be made thereto without departing from the spirit and scope of the application, as set forth in the appended claims.

Claims

1. A process for processing an FPC circuit board for a joystick game controller, characterized by: The steps include: S1, using rolled copper foil to cut the material to obtain the substrate of the FPC circuit board; S2. Perform RTR dry film lamination on the substrate, or perform RTR wet press dry film lamination; S3, perform RTR circuit exposure on the substrate after RTR dry film bonding, and then complete the circuit production through RTR etching technology; S4. Use carbon slurry technology for product design; S5. Use silk screen frame selection technology to print printed circuit graphics; S6. Use thermosetting ink blending technology. The thermosetting ink blending technology uses conductive carbon paste to add to thermosetting ink to form a composite carbon paste ink. The following parameters should be controlled in actual operation of thermosetting ink printing technology: the screen height should be selected at 2mm; the scraping angle should be selected between 30 and 70 degrees; the composite carbon paste ink must be sealed and stored in a low-temperature, dry environment when not in use. It must be removed from the low-temperature environment at least 4 hours in advance before each use and allowed to return to room temperature before use. The carbon conductive ink must be fully stirred before use, and no diluent should be added. Thermosetting ink printing technology is used to complete the printing requirements of FPC board ink, and finally an FPC circuit board is produced that meets the requirements of ink resistance of 5±1KΩ and printing thickness of 20±2um; S7. PSPI ink coating is used to replace the cover film to improve the step difference and voltage deviation.

2. The FPC circuit board processing technology for a joystick game controller according to claim 1, characterized in that: In step S2, the RTR dry film lamination is to first use a PET sheet longer than 1 meter to tape the copper area of ​​the product with double-sided tape and press it flat; The RTR wet-press dry film lamination refers to loading the material with the copper side facing upwards, then laminating and pressing the film using a wet method, and then rewinding the material with the copper side facing inwards.

3. The FPC circuit board processing technology for a joystick game controller according to claim 1, characterized in that: In step S3, the RTR line exposure is performed using RTR fully automatic exposure equipment; The production of the circuit refers to the use of advanced precision vacuum etching technology. The etching section uses the AQUA control system and related equipment to accurately control the fluctuation range of the concentration of chemical solutions used in the etching process within the required range. Other solution sections use a precise automatic solution addition system. The equipment automatically accumulates and calculates the product production volume and automatically adds solutions according to the set addition value.

4. The FPC circuit board processing technology for a joystick game controller according to claim 1, characterized in that: The step S4 specifically includes: appropriately increasing the carbon ink area according to the actual printing result to prevent the carbon ink effective width W from being reduced or the effective length L from being deviated due to the offset of the screen printing, which leads to the carbon resistor opening. The area S of the screen printing carbon ink block is designed to completely cover the entire carbon bridge contact point and the connecting copper sheet; and the design of the effective width W and the effective length L satisfy Ohm's law: R=Rp×WL / S, Rp=5±1KΩ.

5. The FPC circuit board processing technology for a joystick game controller according to claim 1, characterized in that: In the screen printing frame selection technology of step S5, the screen mesh size is selected based on the calculation result of the following relationship plus a margin of 30-50%, and the relationship is: D≥2s+K, M=1 / (Ds); Where: D is the width of the thinnest line that can be printed or the smallest dot diameter; s is the line diameter; K is the aperture; M is the mesh count of the screen.

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