A manufacturing method of a wireless charging FPC

Abstract

The application discloses a kind of wireless charging FPC manufacturing method, including blanking→drilling→black hole→copper plating→paste dry film→exposure→etching→plating lead wire→secondary copper plating→copper→paste blue film→protective film pressing→appearance inspection→electrical performance test, the manufacturing method of wireless charging FPC of the application is improved by protective film pressing process, before pressing, protective film is vacuum false pressure, when pressing, four opening laminates is used, and segmented control is used in laminating process, can provide uniform and stable high temperature and high pressure environment in short time, make protective film and FPC glue solidify rapidly;During laminating process, pressure is evenly distributed on the surface of FPC, it is helpful to make protective film and FPC closely adhere, avoid the defects such as bubble, wrinkle, ensure the flatness of FPC surface, so as to improve the quality and reliability of product, segmented pressure control can effectively avoid the generation of bubble and wrinkle.

Description

Technical Field

[0001] This invention relates to the technical field of flexible circuit boards, and in particular to a method for manufacturing a wireless charging FPC. Background Technology

[0002] With the increasing popularity of wireless charging for electronic devices, the quality and performance of wireless charging FPCs have received widespread attention. During the manufacturing process of wireless charging FPCs, processes such as etching, electroplating, lamination, and protective film bonding can all affect the electrical performance of the FPC, thus reducing the quality of the product. The bonding of the protective film is particularly problematic. When using thin protective films, their poor filling properties can easily lead to air bubbles between the protective film and the FPC during bonding. These air bubbles can affect the electrical performance and stability of the FPC, and may even cause problems such as partial short circuits. Furthermore, when the protective film is combined with a thicker copper layer, the thickness of the copper layer and the thinner cover film mean that the adhesive thickness cannot be adequately filled. This results in poor filling properties of the thin protective film, making it prone to bonding air bubbles; thin protective films with thin PI layers and thick copper layers can easily cause the protective film to crack; and there are also issues with wrinkled protective film bonding.

[0003] In view of this, the present invention addresses the problems affecting the electrical performance of wireless charging FPCs in the existing manufacturing process and proposes a manufacturing method for wireless charging FPCs, aiming to improve the service life and stability of wireless charging FPCs. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for manufacturing wireless charging FPC that can significantly improve the quality of wireless charging FPC products, increase the service life and stability of wireless charging FPC, and meet the demand of the wireless charging market for high-quality FPC.

[0005] To achieve the above objectives, the solution of the present invention is:

[0006] A method for manufacturing a wireless charging FPC includes the following steps:

[0007] Step S1: Material preparation, selecting PI as the substrate for FPC;

[0008] Step S2: Drilling, drilling holes in the PI substrate;

[0009] Step S3, Black Hole: Perform black hole treatment on the drilled FPC to form a conductive layer on the hole wall of the FPC.

[0010] Step S4: Copper plating, a uniform copper foil is applied to both sides of the FPC.

[0011] Step S5: Apply dry film. Apply a layer of dry film to the copper surfaces on both sides of the FPC.

[0012] Step S6: Exposure, transferring the image from the film to the dry film through exposure plate making;

[0013] Step S7: Etching. Coils are etched on both sides of the FPC using an etching process, and the coils on both sides are made conductive through the vias. In addition to etching the coils, the pre-designed circuitry of the FPC also needs to be etched.

[0014] Step S8: Electroplating leads. Reserve or create electroplating leads on the edge of the pre-made circuit pattern, and design test PADs on the electroplating leads.

[0015] Step S9: Secondary copper plating. Secondary copper plating is performed on the coils and circuits on both sides to achieve the specified copper thickness.

[0016] Step S10: Pour copper in areas where there is no copper.

[0017] Step S11: Apply blue film. Apply blue film to the areas with wiring and solder joints.

[0018] Step S12: Pressing the protective film. Before pressing, the protective film is vacuum-pressed. During pressing, a four-opening lamination is used, and segmented control is adopted. Low-pressure pressing is used in the initial pressing stage, and after a period of time, a slow pressure increase stage is entered. In the final stage of pressing, a stable pressure is maintained for a period of time.

[0019] Step S13: Visual inspection. After pressing the protective film, perform a visual inspection to ensure that the protective film is well adhered and free of bubbles, wrinkles or damage.

[0020] Step S14: Electrical performance test. Test the electrical performance of the FPC to ensure that the wireless charging function is normal. This mainly includes checking the continuity and insulation of the circuit, as well as whether there are any short circuits or other problems.

[0021] Further, in step S2, before drilling, the PI substrate is cleaned and then fixed to ensure that the substrate does not shift during the drilling process.

[0022] Furthermore, after the second copper plating in step S9, line width compensation is performed. The line width compensation is consistent with the copper thickness and the minimum line spacing is ≥0.055mm.

[0023] Further, in step S11, the blue film completely covers the circuit portion of the flexible circuit board and areas that have a significant impact on the performance of the circuit board, including the area around the mounting positions of sensitive components such as chips and sensors.

[0024] Further, in step S12, before laminating the protective film, the protective film is first subjected to micro-etching to increase the surface roughness of the protective film, and the FPC to be laminated is cleaned.

[0025] Furthermore, the micro-etching treatment of the protective film employs plasma treatment. The protective film is placed in a plasma treatment device, and the surface of the treated protective film exhibits a nanoscale roughness. Active functional groups are simultaneously introduced in the plasma treatment device to enhance the adhesion between the protective film and the FPC surface. A layer of composite nanomaterial is coated on the surface of the FPC to be pressed. The main components of the composite nanomaterial include nano-silica, organosilicon resin, and coupling agent. The composite nanomaterial coating fills the tiny pores on the FPC surface and undergoes chemical bonding with the active functional groups on the surface of the protective film during the pressing process.

[0026] Furthermore, the pressure head of the four-opening laminator adopts an elastic buffer pressure head, which automatically adjusts the pressure distribution according to the actual conditions of the protective film and the surface to be pressed.

[0027] Furthermore, in step S12, the specific steps of the four-opening lamination are as follows: In the initial pressing stage, the pressure is set to 20 kg / cm². 2 The pressing time is set to 5 minutes, followed by a slow pressurization phase where the pressure is increased to 60 kg / cm². 2 The entire pressurization phase lasted 5 minutes; in the final stage of pressing, the pressure was set to 100 kg / cm². 2 Maintain this pressure for 70 minutes.

[0028] Furthermore, after step S12, when the protective film is pressed, the FPC is immediately cooled. The cold pressing pressure is set to 100 kg, the vacuum release time is set to 2 min, the cold pressing time is set to 45 min, the pre-vacuum is evacuated for 3 min, and the initial pressure is 20 kg. This further stabilizes the bond between the protective film and the FPC surface and reduces wrinkling problems caused by temperature changes.

[0029] By adopting the above solution, the manufacturing method of the wireless charging FPC of the present invention has the following advantages compared with the prior art: The present invention improves the protective film lamination process by applying vacuum sham pressure to the protective film before lamination, allowing the protective film to better adhere to the surface of the FPC, eliminating air, and avoiding defects such as bubbles and delamination during subsequent processing. During lamination, a four-opening lamination process is used, and the lamination process is controlled in stages, providing a uniform and stable high-temperature and high-pressure environment in a short time, allowing the adhesive between the protective film and the FPC to cure rapidly. During lamination, the pressure is evenly distributed on the FPC surface, helping to ensure a tight fit between the protective film and the FPC, avoiding defects such as bubbles and wrinkles, ensuring the flatness of the FPC surface, thereby improving product quality and reliability. The staged pressure control effectively avoids the generation of bubbles and wrinkles. If high pressure is used from the beginning, air can easily be trapped between the protective film and the FPC, forming bubbles, or causing wrinkles in the protective film. By gradually increasing the pressure, sufficient time is allowed for air to escape, while simultaneously ensuring that the protective film adheres evenly to the FPC. Attached Figure Description

[0030] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0031] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0032] like Figure 1 As shown, this invention discloses a method for manufacturing a wireless charging FPC, which includes the following steps:

[0033] Step S1: Material preparation. Select a PI substrate that is heat-resistant, has good insulation, is antistatic, and is flat.

[0034] Step S2: Drilling. Drill holes in the PI substrate. Before drilling, clean the PI substrate and fix it in place to ensure that the substrate does not shift during the drilling process.

[0035] Step S3, Black Hole: Perform black hole treatment on the FPC after drilling to form a conductive layer on the hole wall of the FPC, so that a conductive layer can be formed after drilling, which facilitates the conduction of the upper and lower copper layers.

[0036] Step S4: Copper plating. Apply a uniform layer of copper foil to both sides of the FPC. Multiple electroplating operations can be performed depending on the actual situation.

[0037] Step S5: Apply dry film. Apply a layer of dry film to the copper surfaces on both sides of the FPC to facilitate subsequent exposure and circuit formation.

[0038] Step S6: Exposure, transferring the image from the film onto the dry film using exposure plate-making technology.

[0039] Step S7: Etching. Coils are etched on both sides of the FPC using an etching process, and the coils on both sides are made conductive through through holes. The shape and parameters of the coils can be adjusted according to actual needs. In addition to etching the coils, the pre-designed circuits of the FPC also need to be etched, including power lines, communication lines and grounding lines.

[0040] Step S8: After etching the coil and circuit, electroplating leads are used to achieve subsequent processes such as thickening the copper plating. By leaving or creating electroplating leads at the edges of the pre-made circuit pattern, the current can be evenly distributed on the surface of the copper layer to be electroplated, ensuring the uniformity of the electroplating effect. Test PADs are designed on the electroplating leads. In addition to facilitating circuit performance testing, the test PADs can also serve as contact points for monitoring the electroplating effect. When the wireless charging FPC malfunctions, the test PADs provide convenient test points for fault diagnosis. Repair personnel can quickly locate the fault location by applying test signals or measuring relevant parameters on the test PADs, determining whether the problem lies with the electroplating leads themselves or with other connected components or circuits, facilitating repair. The design of the test PADs can also help evaluate the impact of the electroplating leads on signal transmission.

[0041] Step S9: Secondary copper plating. Secondary copper plating is performed on both sides of the coil and circuit. This can be done in multiple steps depending on the actual situation, so that the copper thickness reaches the specified thickness.

[0042] After the second copper plating, line width compensation is performed. The line width compensation is consistent with the copper thickness and the minimum line spacing is ≥0.055mm.

[0043] Step S10: Copper Laying. Large areas without copper can cause unevenness in the product. Therefore, this invention lays copper appropriately in the copper-free areas. This not only makes the FPC surface smoother, but also connects the copper-free areas to the ground plane to form a complete shielding layer. This reduces electromagnetic radiation and improves anti-interference capabilities, allowing the wireless charging device to better resist external interference when working, while also avoiding interference with other electronic devices.

[0044] Step S11: Apply blue film. Apply blue film to the areas with circuits and solder joints. The blue film should completely cover the circuit part of the flexible circuit board to ensure that the circuit is protected and prevented from being scratched or short-circuited during subsequent processing or use. In addition to copper circuits and solder joints, it is also necessary to cover areas that have an important impact on the performance of the circuit board, including the area around the installation position of sensitive components such as chips and sensors. Although these areas do not have copper, they may be affected by static electricity, moisture or physical impact. The blue film can provide additional protection.

[0045] Step S12: Pressing the protective film. In order to overcome the problems of protective film pressing, the protective film is first subjected to micro-etching treatment to increase the surface roughness of the protective film, improve the filling capacity of the protective film, and reduce the possibility of air bubbles being generated during pressing. The micro-etching treatment can be carried out by plasma treatment. The protective film is placed in the plasma treatment equipment. The surface of the treated protective film exhibits nanoscale roughness and micro-rough structure. The active functional groups introduced in the plasma treatment equipment at the same time enhance the adhesion between the protective film and the FPC surface.

[0046] After cleaning the FPC to be laminated, remove surface oil, dust, and other impurities. Then, coat the FPC surface with a layer of composite nanomaterial, whose main components include nano-silica, organosilicon resin, and a small amount of coupling agent. The composite nanomaterial coating can fill the tiny pores on the FPC surface and chemically bond with the active functional groups on the protective film surface during the lamination process, further improving the bonding force between the two and reducing the generation of bubbles.

[0047] Before lamination, the protective film is subjected to vacuum dummy pressing to ensure better adhesion to the FPC surface, eliminate air, and prevent defects such as bubbles and delamination during subsequent processing.

[0048] During lamination, a four-opening lamination process is used, which can provide a uniform and stable high-temperature and high-pressure environment in a short time, allowing the adhesive between the protective film and the FPC to cure quickly. During the lamination process, the pressure is evenly distributed on the FPC surface, which helps to ensure that the protective film and the FPC are tightly bonded, avoiding defects such as bubbles and wrinkles, ensuring the flatness of the FPC surface, thereby improving the quality and reliability of the product.

[0049] For four-opening lamination, a segmented control method is used. In the initial lamination stage, low-pressure lamination is used, with the pressure set at 20 kg / cm². 2 The pressing time is set to 5 minutes. This pressure is sufficient to lay the protective film flat on the FPC, but it will not cause deformation of the protective film or the FPC due to excessive pressure. After 5 minutes, a slow pressure increase stage begins. Appropriately increasing the pressure can make the protective film adhere more tightly to the FPC. The pressure in this stage is increased to 60 kg / cm². 2 The entire pressurization phase lasts 5 minutes. This pressure range helps to expel tiny air bubbles between the protective film and the FPC, ensuring there are no gaps between them and thus improving bonding accuracy. In the final stage of pressing, the pressure value is set to 100 kg / cm². 2 Maintaining this pressure for 70 minutes allows the adhesive between the protective film and the FPC to fully cure and bond smoothly.

[0050] The pressure head of the four-opening laminator adopts an elastic buffer pressure head to avoid cracking the protective film. The elastic buffer pressure head can automatically adjust the pressure distribution according to the actual situation of the protective film and the surface to be pressed, further reducing the generation of air bubbles and the risk of cracking the protective film.

[0051] The present invention employs segmented pressure control, which can effectively avoid the formation of bubbles and wrinkles. If high pressure is used from the beginning, it is easy to trap air between the protective film and the FPC, forming bubbles, or causing wrinkles in the protective film. By gradually increasing the pressure, the air can have enough time to escape, while the protective film is evenly adhered to the FPC.

[0052] After pressing, the FPC is immediately cooled. The cold pressing pressure is set to 100 kg, the vacuum release time is set to 2 min, the cold pressing time is set to 45 min, the pre-vacuum is set to 3 min, and the initial pressure is 20 kg. Cold pressing further stabilizes the bond between the protective film and the FPC surface, reducing wrinkling problems caused by temperature changes.

[0053] Step S13: Visual inspection. After pressing the protective film, a visual inspection should be performed first to ensure that the protective film is well adhered and free from problems such as bubbles, wrinkles or damage.

[0054] Step S14: Electrical performance test. Test the electrical performance of the circuit board to ensure that the wireless charging function is normal. This mainly includes checking the continuity and insulation of the circuits, as well as whether there are any short circuits or other problems.

[0055] The above embodiments are not intended to limit the product form and style of the present invention. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims

1. A method for manufacturing a wireless charging FPC, characterized in that, Includes the following steps: Step S1: Material preparation, selecting PI as the substrate for FPC; Step S2: Drilling, drilling holes in the PI substrate; Step S3, Black Hole: Perform black hole treatment on the drilled FPC to form a conductive layer on the hole wall of the FPC. Step S4: Copper plating, a uniform copper foil is applied to both sides of the FPC. Step S5: Apply dry film. Apply a layer of dry film to the copper surfaces on both sides of the FPC. Step S6: Exposure, transferring the image from the film to the dry film through exposure plate making; Step S7: Etching. Coils are etched on both sides of the FPC using an etching process, and the coils on both sides are made conductive through the vias. In addition to etching the coils, the pre-designed circuitry of the FPC also needs to be etched. Step S8: Electroplating leads. Reserve or create electroplating leads on the edge of the pre-made circuit pattern, and design test PADs on the electroplating leads. Step S9: Secondary copper plating. Secondary copper plating is performed on the coils and circuits on both sides to achieve the specified copper thickness. Step S10: Pour copper in areas where there is no copper. Step S11: Apply blue film. Apply blue film to the areas with wiring and solder joints. Step S12: Press the protective film; Before laminating the protective film, the protective film is first micro-etched to increase the surface roughness of the protective film, and the FPC to be laminated is then cleaned. The micro-etching treatment of the protective film is carried out by plasma treatment. The protective film is placed in the plasma treatment equipment, and the surface of the treated protective film exhibits a nano-level roughness. Active functional groups are introduced at the same time in the plasma treatment equipment to enhance the adhesion between the protective film and the FPC surface. A composite nanomaterial is coated on the surface of the FPC to be pressed. The main components of the composite nanomaterial include nano-silica, organosilicon resin and coupling agent. The composite nanomaterial coating fills the tiny pores on the surface of the FPC and chemically bonds with the active functional groups on the surface of the protective film during the pressing process. Before lamination, the protective film is vacuum-pressed. During lamination, a four-opening lamination method is used, and segmented control is adopted. Low-pressure lamination is used in the initial lamination stage, and after a period of time, a slow pressure increase stage is entered. In the final stage of lamination, a stable pressure is maintained for a period of time. Step S13: Visual inspection. After pressing the protective film, perform a visual inspection to ensure that the protective film is well adhered and free of bubbles, wrinkles or damage. Step S14: Electrical performance test. Test the electrical performance of the FPC to ensure that the wireless charging function is normal.

2. The method for manufacturing a wireless charging FPC as described in claim 1, characterized in that: Step S2: Before drilling, clean the PI substrate and then fix the substrate to ensure that it will not shift during the drilling process.

3. The method for manufacturing a wireless charging FPC as described in claim 1, characterized in that: After the second copper plating in step S9, line width compensation is performed. The line width compensation is consistent with the copper thickness and the minimum line spacing is ≥0.055mm.

4. The method for manufacturing a wireless charging FPC as described in claim 1, characterized in that: Step S11: The blue film completely covers the circuit portion of the flexible circuit board and the areas that have a significant impact on the performance of the circuit board, including the area around the mounting location of sensitive components.

5. The method for manufacturing a wireless charging FPC as described in claim 1, characterized in that: The pressure head of the four-opening laminator is an elastic buffer pressure head, which automatically adjusts the pressure distribution according to the actual situation of the protective film and the surface to be pressed.

6. The method for manufacturing a wireless charging FPC as described in claim 1, characterized in that: In step S12, the specific steps of four-opening lamination are as follows: In the initial pressing stage, the pressure is set to 20 kg / cm². 2 The pressing time was set to 5 minutes, followed by a slow pressurization phase where the pressure was increased to 60 kg / cm². 2 The entire pressurization phase lasted 5 minutes; in the final stage of compression, the pressure was set to 100 kg / cm². 2 Maintain this pressure for 70 minutes.

7. The method for manufacturing a wireless charging FPC as described in claim 1, characterized in that: After the protective film is pressed, the FPC is immediately cooled. The cold pressing pressure is set to 100 kg, the vacuum release time is set to 2 min, the cold pressing time is set to 45 min, the pre-vacuum is evacuated for 3 min, and the initial pressure is 20 kg.

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