Continuous production method and apparatus for flexible die-cut wiring boards

Abstract

The present application relates to the technical field of circuit board die cutting, and discloses a continuous production method and equipment for flexible die cutting circuit boards, which comprises the following steps: die cutting a coiled copper foil to form a circuit pattern, and automatically removing waste from the die cut coiled copper foil; passing the waste-removed coiled copper foil between a pair of steel rollers arranged oppositely, and rolling the coiled copper foil by the weight of the steel rollers to eliminate the curling and internal stress of the coiled copper foil; heating and pressing the rolled coiled copper foil and a first insulating film; heating and pressing the coiled copper foil with the first insulating film and a second insulating film to form a three-layer composite material tape; and performing outer forming die cutting on the three-layer composite material tape to obtain a flexible die cutting circuit board semi-finished product. The present application significantly improves the flatness of the flexible die cutting circuit board product, reduces the poor bonding rate caused by copper foil warping, and improves the reliability of multi-layer compounding.

Description

Technical Field

[0001] This invention relates to the field of circuit board die-cutting technology, and in particular to a continuous production method and equipment for flexible die-cut circuit boards. Background Technology

[0002] The existing flexible circuit body mainly consists of PI or PET pre-coated with thermosetting adhesive and copper foil (aluminum foil) integrally formed on a rotary die-cutting machine. The process employs a multi-axis, multi-asynchronous die-cutting principle, die-cutting the copper foil (aluminum foil) and PI (PET) from their outlines, then pressing them together with rollers at specific positions to achieve integral forming. A heating roller pressing process is added to the rotary die shaft, which improves the sealing accuracy of the copper foil and PI composite materials. However, the lack of a process to effectively control the curling and internal stress generated after die-cutting the metal electrodes results in poor product flatness, numerous bonding bubbles, impaired circuit precision, and limits further increases in production line speed. Summary of the Invention

[0003] In order to overcome the problems of edge curling or internal stress in the existing flexible film die-cutting composite process, the present invention provides a continuous production method and equipment for flexible die-cut circuit boards.

[0004] In a first aspect, the present invention provides a continuous production method for flexible die-cut circuit boards, comprising the following steps: The copper foil rolls are die-cut to form circuit patterns, and the die-cut copper foil rolls are automatically discharged. After the waste is discharged, the copper foil roll is passed between a pair of steel rollers arranged opposite each other. The weight of the steel rollers themselves is used to roll and press the copper foil roll to eliminate the curling and internal stress of the copper foil roll. The rolled copper foil is heated and pressed together with the first insulating film; The roll of copper foil with the first insulating film pressed on it is heated and pressed together with the second insulating film to form a three-layer composite strip; The three-layer composite strip is shaped and die-cut to obtain a flexible die-cut circuit board semi-finished product.

[0005] According to one specific embodiment, in the above production method, when die-cutting the coiled copper foil, the tension of the feeding shaft is set to 15~35N, and the speed ratio of the feed roller is set to 0.9990~0.9999.

[0006] According to one specific embodiment, the above-described production method further includes: Before die-cutting the coiled copper foil, the coiled copper foil is laminated with a carrier film, and then the laminated material is die-cut. The tension of the feeding shaft of the carrier film is set to 15~35N, and the speed ratio of the machine base and the main material machine base is kept consistent.

[0007] According to one specific embodiment, in the above production method, the temperature for performing the heating and pressing is set to 150~180°C.

[0008] According to a specific embodiment, in the above production method, the steps of heating and pressing the rolled copper foil with the first insulating film and heating and pressing the rolled copper foil with the first insulating film with the second insulating film are both performed at a temperature of 150~180°C.

[0009] According to a specific embodiment, in the above production method, after heating and pressing the rolled copper foil with the first insulating film and the second insulating film, the method further includes: heating and pressing the formed three-layer composite strip at a temperature of 150~180°C for the third time.

[0010] According to one specific embodiment, in the above production method, when the coiled copper foil is rolled by the weight of the steel roller itself, no external pressure other than its own weight is applied to the steel roller.

[0011] According to one specific embodiment, the above production method, after the three-layer composite strip is shaped and die-cut, further includes: For the flexible die-cut circuit board semi-finished product, CCD size detection is performed simultaneously on the production line; For the semi-finished flexible die-cut circuit boards that have completed dimensional inspection, marking and printing are performed simultaneously on the production line.

[0012] Secondly, the present invention provides a continuous production equipment for flexible die-cut circuit boards, comprising: The die-cutting and waste removal unit is used to die-cut coil copper foil to form circuit patterns and automatically remove waste from the die-cut coil copper foil. The precision pressing and leveling unit is located after the die-cutting waste removal unit and includes a pair of steel rollers arranged opposite each other. The precision pressing and leveling unit is configured to pass the waste-removed coiled copper foil between the pair of steel rollers arranged opposite each other, and to roll the coiled copper foil by relying on the weight of the steel rollers themselves to eliminate the curling and internal stress of the coiled copper foil. The heating and pressing unit is located after the precision pressing and leveling unit. It is used to heat and press the rolled copper foil with the first insulating film and the second insulating film in sequence to form a three-layer composite strip. The forming and die-cutting unit is located after the heating and pressing unit and is used to perform shape forming and die-cutting on the three-layer composite strip to obtain a flexible die-cut circuit board semi-finished product.

[0013] According to one specific embodiment, in the above-mentioned production equipment, the steel roller of the precision pressing and leveling unit is not connected to any driving device or pressurizing device for applying pressure other than its own weight. The heating and pressing unit includes two sets of heating rollers, which are used for the first heating and pressing of the rolled copper foil with the first insulating film and the second heating and pressing with the second insulating film, respectively. The temperature of the heating rollers is set to 150~180℃.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention introduces a precision pressing and leveling process using the weight of a steel roller after die-cutting and before heating and pressing of the copper foil roll. This solves the problem in existing flexible die-cut circuit board production processes where copper foil curling and residual internal stress caused by die-cutting are not effectively eliminated, leading to poor product flatness and subsequent air bubbles or delamination during lamination. This process utilizes the uniform, stable, and pressure-free roller pressure generated by the weight of the steel roller to physically smooth the die-cut copper foil lines, actively eliminating initial defects. Based on this, the leveled copper foil, with its internal stress released, is then heated and pressed with an insulating film, avoiding the quality risks associated with directly laminating uneven copper foil. Through the synergistic effect of these techniques, this invention significantly improves the flatness of flexible die-cut circuit board products, reduces the bonding failure rate caused by copper foil warping, enhances the reliability of multilayer lamination, and creates the preconditions for further increasing production line operating speed. Attached Figure Description

[0015] Figure 1 This is a schematic flowchart of a continuous production method for flexible die-cut circuit boards provided in an embodiment of the present invention.

[0016] Figure 2 This is a schematic diagram of the structure of a continuous production equipment for flexible die-cut circuit boards provided in an embodiment of the present invention. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0018] Unless otherwise specified, in the description of specific embodiments of the present invention, the terms "horizontal," "vertical," "suspended," "parallel," and "coaxial" do not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, parallel, or coaxial. Slight tilt or deviation is permissible, as long as it does not affect the normal function of the relevant component. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," not that the structure must be completely horizontal, but can be slightly tilted. "Coaxial" means that two components are arranged as coaxially as possible, so that they can move in a coaxial or approximately coaxial manner when their relative positions change. Alternatively, it can be simplified to mean that the corresponding device / component / element, when arranged in a "horizontal," "vertical," "suspended," "parallel," or "coaxial" direction, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. For example, the deviation in the "coaxial" direction should be controlled within 0.2-1mm, preferably within 0.2-0.5mm. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the present invention.

[0019] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0020] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as two, three, four, five, six, seven, eight, or nine, and can even exceed nine.

[0021] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to connection methods commonly used in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0022] Before providing a detailed description of the technical solution of this invention, the key technical terms and applicable scenarios involved will be explained first.

[0023] In the description of this invention, coiled copper foil refers to a strip of metallic copper foil wound into a roll, serving as a conductive material for forming circuit patterns. In this invention, the thickness of the coiled copper foil can be selected according to product requirements; for example, the thickness ranges from 25 μm to 120 μm. Waste removal refers to the process of peeling and removing excess waste generated after die-cutting from the product strip during the die-cutting process. In this invention, waste removal specifically refers to removing excess copper foil outside the circuit patterns.

[0024] This invention is applicable to continuous and high-efficiency production scenarios for flexible die-cut circuit boards. Specifically, the continuous production method and equipment provided by this invention can be applied to production lines that use multi-station rotary die-cutting machines to integrally form flexible circuit boards. This production line achieves fully automated production from raw materials to semi-finished or finished products by simultaneously feeding, asynchronously die-cutting, layering and laminating, precision pressing and leveling, shaping, and online inspection and printing of various roll materials such as copper foil, insulating film, and carrier film.

[0025] The technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0026] In one exemplary embodiment of the present invention, a continuous production method for flexible die-cut circuit boards is provided. This method can be executed on a multi-station rotary die-cutting machine, which exemplaryly has twenty-six stations, each of which can be configured with functional units such as a feeding shaft, a die-cutting blade holder, a pressing roller, a heating roller, and a waste discharge roller. However, those skilled in the art should understand that this number of stations is merely an example and can be adjusted according to the production line configuration in actual implementation.

[0027] Please refer to Figure 1 It illustrates a flowchart of a continuous production method for flexible die-cut circuit boards provided by an embodiment of the present invention, comprising the following steps: Step 1: Die-cut the copper foil roll to form circuit patterns, and automatically remove waste from the die-cut copper foil roll.

[0028] Specifically, the coiled copper foil is loaded onto the feeding shaft at the front end of the rotary die-cutting machine. The feeding shaft, controlled by a program, applies a preset tension to the strip, ensuring the coiled copper foil remains flat and wrinkle-free during its feeding process. Subsequently, the coiled copper foil is fed into the die-cutting station. At the die-cutting station, the coiled copper foil is asynchronously linearly die-cut using a rotary die with a pre-designed graphic outline. After die-cutting, immediately using a waste removal blade or waste removal roller, excess copper waste outside the circuit pattern is peeled off from the strip and wound up, thus forming the desired circuit pattern on the remaining copper foil strip.

[0029] This step, through precise tension control and die-cutting, yields circuit patterns with neat lines and high dimensional accuracy. However, copper foil circuits that have only undergone die-cutting and waste removal often have varying degrees of micro-curling at the edges, and residual internal stress has accumulated within the material due to shearing. If these curls and internal stresses are not addressed in subsequent processes, they will directly affect the final flatness and composite reliability of the product.

[0030] Step 2: Pass the copper foil roll after waste removal between a pair of steel rollers arranged opposite each other. The weight of the steel rollers themselves is used to roll and press the copper foil roll to eliminate the curling edges and internal stress of the copper foil roll.

[0031] This step is one of the core processes of this invention, namely, introducing a precision pressing and leveling process after the waste removal process. Exemplarily, this process is completed at two consecutive stations on a rotary die-cutting machine. Upper and lower steel rollers are respectively installed at these two stations, with the upper and lower rollers arranged opposite each other to form a gap through which the material strip can pass.

[0032] The copper foil roll, after being degassed and bearing the circuit pattern, travels between the pair of steel rollers during the feeding process. In this invention, the steel rollers are conventional solid steel rollers, and during the leveling process, they do not exert any additional pressure on the pair of steel rollers other than their own weight through cylinders, lead screws, springs, or any other driving or pressurizing devices. That is, the roller pressure borne by the strip comes entirely from the weight of the upper steel roller itself.

[0033] The uniform and continuous pressure generated by the weight of the steel rollers effectively smooths the copper foil circuitry. This process significantly eliminates localized edge curling and warping caused by die-cutting in step 1, and releases and homogenizes residual non-uniform internal stress within the copper foil. After this step, the surface of the copper foil circuitry becomes more regular and smooth, laying the foundation for subsequent high-quality lamination and fundamentally reducing problems such as product warping and delamination caused by the material's own stress. Simultaneously, because no additional pressure is required, the delicate copper foil circuitry is protected, preventing deformation or damage due to excessive pressure.

[0034] It is understood that, in the description of the embodiments of the present invention, a steel roller refers to a cylindrical roller shaft made of steel that can rotate freely about its axis.

[0035] Step 3: Heat and press the rolled copper foil with the first insulating film.

[0036] After precision pressing and leveling, the material strip continues to feed into the heating and pressing station. For example, the first insulating film is released from the middle feeding shaft. This first insulating film can be pre-cut in part by an asynchronous die according to product design requirements.

[0037] Subsequently, the processed first insulating film and the rolled copper foil, which has been finely pressed and leveled in step 2, are simultaneously fed into a set of heated rollers for pressure bonding. A thermosetting adhesive layer is coated on the side of the first insulating film facing the copper foil. The heat transferred by the heated rollers causes the thermosetting adhesive layer to reach its activation temperature, generating adhesion. Under the pressure of the heated rollers, the copper foil circuitry is firmly transferred and bonded to the first insulating film.

[0038] Step 4: Heat and press the rolled copper foil with the first insulating film onto the second insulating film to form a three-layer composite strip.

[0039] After lamination with the first insulating film is completed, the resulting double-layer composite strip continues to feed. Exemplarily, the second insulating film is released from another middle feed shaft, and its shape can also be pre-cut in part.

[0040] The second insulating film is placed over the exposed copper foil side of the double-layer composite strip and fed together with it into a subsequent heating roller group for a second heating and pressing. Under the combined action of heating and pressure, the thermosetting adhesive layer on the second insulating film is activated and bonded, thereby completely encapsulating the copper foil circuitry between the first and second insulating films, forming a three-layer composite strip consisting of the first insulating film, the copper foil circuitry, and the second insulating film.

[0041] In the description of this invention, the insulating film refers to a polyimide or polyester film coated with thermosetting adhesive, used to cover and protect circuit patterns, providing electrical insulation and physical support. In this invention, the first insulating film and the second insulating film can respectively correspond to the A-side cover film and the B-side cover film of the flexible circuit board. For example, the first insulating film may be an A-side PI cover film, and the second insulating film may be a B-side PI cover film.

[0042] Step 5: Perform shape forming and die cutting on the three-layer composite strip to obtain a flexible die-cut circuit board semi-finished product.

[0043] After completing all the composite processes, the three-layer composite strip is conveyed to the shape forming and die-cutting station. At this station, the multi-layer composite strip is cut or partially cut into shape according to the outer contour of the final product using a pre-designed die-cutting mold, thereby obtaining an independent flexible die-cut circuit board semi-finished product with the target shape from the continuous strip.

[0044] Thus, through the continuous operation of steps 1 to 5, the semi-finished flexible die-cut circuit board of the present invention can be obtained. This method, by combining self-weight leveling with heating composite processes, solves the pain points of poor product flatness and high internal stress leading to low yield in existing processes.

[0045] In one possible implementation, to improve the smoothness of material feeding and protect the main material, the process includes laminating the coiled copper foil with a carrier film before die-cutting. For example, at the front station of a rotary die-cutting machine, the coiled copper foil and a roll of carrier film are simultaneously fed into a composite die holder, causing the carrier film to adhere to the back of the copper foil. Subsequently, the copper foil supported by the carrier film is subjected to further die-cutting operations. The introduction of the carrier film effectively enhances the tensile strength and feeding stability of the thin copper foil strip, preventing breakage or deformation during high-speed feeding and multi-blade die-cutting.

[0046] In the description of this invention embodiment, the carrier film refers to a thin film material used to assist in supporting the feeding of the coiled copper foil during the die-cutting process. After fulfilling its auxiliary function, the carrier film is peeled off in subsequent processes or before the final product is formed, and does not constitute part of the final product.

[0047] In one possible implementation, to achieve optimal die-cutting quality and material feeding stability, specific tension parameter ranges are set for each feed shaft involved in the above steps. Specifically, when die-cutting coiled copper foil, the tension of its feed shaft is set within the range of 15 to 35 Newtons (N). This range ensures that the copper foil is taut and flat for accurate die-cutting, without causing the copper foil to stretch, deform, or break due to excessive tension.

[0048] Meanwhile, to ensure precise matching of the conveyor speed and avoid material accumulation or stretching due to speed differences, the speed ratio of each feed roller in this embodiment of the invention is also precisely set. For example, in each relevant station of copper foil die-cutting, the speed ratio of the feed roller is set within the range of 0.9990 to 0.9999. This setting provides extremely slight tension compensation for the conveyor belt, further ensuring smooth material feeding. Similarly, when using a carrier film, the tension of the carrier film's feed shaft is also set to 15 to 35 Newtons (N), and the speed ratio of each machine base it passes through is strictly consistent with the speed ratio of the feed roller of the main copper foil to maintain uniform overall tension of the composite material.

[0049] In one possible implementation, the embodiments of the present invention systematically optimize the temperature for heat pressing. Unlike the high-temperature pressing methods commonly used in the prior art, the present invention sets the temperature for heat pressing within the range of 150 to 180 degrees Celsius (°C). Specifically, the operating temperatures of both the heating roller used for laminating the first insulating film and the heating roller used for laminating the second insulating film are precisely controlled within this temperature range.

[0050] Repeated experiments revealed that when using PI (polyimide) or PET (polyester) insulating films pre-coated with a specific thermosetting adhesive, a relatively low temperature range of 150 to 180°C is sufficient to fully activate the thermosetting adhesive layer and achieve a stable bond with the copper foil. More importantly, this low-temperature process offers dual technical advantages: firstly, it significantly reduces the thermal stress generated at high temperatures due to the difference in thermal expansion coefficients between the copper foil and the insulating film, and combined with the mechanical pre-leveling in step 2, it yields products with extremely high flatness; secondly, the reduced heating temperature shortens the time required for heating and subsequent cooling, directly creating the prerequisite for increasing the overall production line's operating speed.

[0051] In one possible implementation, to further enhance interlayer bonding and improve the product's anti-delamination ability, this embodiment of the invention adds an overall heat treatment step after the above-mentioned heating and pressing of the second insulating film and the first insulating film / copper foil composite. That is, the already formed three-layer composite strip is subjected to a third heating and pressing process using another set of heating rollers. The temperature of this third heating and pressing is also set within the range of 150 to 180°C. This pressurized heating treatment allows for secondary activation and penetration of the thermosetting adhesive between the first insulating film, the second insulating film, and the intermediate copper foil layer, eliminating any possible micro-interfacial voids and achieving a better adhesion state for the three layers, thereby ensuring reliable composite strength even under high-efficiency production cycles.

[0052] In one possible implementation, in order to achieve real-time, 100% full inspection of product size and quality and improve the level of intelligent management of the production process, after the three-layer composite strip is shaped and die-cut, the embodiment of the present invention further includes seamlessly integrating online inspection and marking processes into the continuous production line.

[0053] Specifically, as the semi-finished flexible die-cut circuit boards continue to move along the conveyor belt after forming and die-cutting, they first pass through one or more CCD vision inspection stations. These stations are equipped with high-resolution industrial cameras and light sources, which can perform high-speed photography and real-time calculation and analysis on preset inspection items such as key dimensions, hole position accuracy, and line spacing of each product. If defective products such as those with out-of-tolerance dimensions are found, the system will record and issue an alarm.

[0054] Following the CCD inspection station, an online coding station is set up. The coding device synchronously prints corresponding identification information, such as a unique product identifier, production batch number, or a pass / fail status code, onto the surface of each passing product based on signals transmitted from the upstream CCD inspection system or according to preset coding rules. This integrated "die-cutting-inspection-printing" production method eliminates the cumbersome offline inspection and subsequent manual sorting and labeling processes of traditional methods, greatly improving production efficiency and quality management.

[0055] In one possible implementation, to further clarify the technical solution of the present invention, in step 2, when rolling the coiled copper foil using the weight of the steel roller itself, no external pressure other than its own gravity is applied to the steel roller. Exemplarily, this means that no cylinder piston rod, no pressure screw, and no counterweight or spring, or any other mechanism capable of transmitting additional downward pressure to the steel roller, are connected to the bearing housing of the steel roller. The rolling effect is purely produced by the inherent weight of the upper steel roller. This design completely eliminates the risk of process instability and product damage caused by manually adjusting the pressure, ensuring the uniformity and reproducibility of the leveling effect.

[0056] Based on the above-described method implementation schemes, one embodiment of the present invention also provides a continuous production equipment for flexible die-cut circuit boards, which is used to perform the continuous production method described in any of the above embodiments.

[0057] The continuous production equipment mainly includes the following components arranged sequentially along the material conveyor belt: a die-cutting and waste removal unit, a precision pressing and leveling unit, a heating and pressing unit, and a forming and die-cutting unit.

[0058] The die-cutting and waste removal unit is used to die-cut the coiled copper foil loaded at the front end of the equipment to form circuit patterns on the copper foil strip, and immediately removes the excess non-circuit copper waste from the strip through the waste removal mechanism.

[0059] The precision pressing and leveling unit is located downstream of the die-cutting waste removal unit. The core component of this unit is a pair of steel rollers mounted opposite each other. This precision pressing and leveling unit is configured to receive the already waste-removed coiled copper foil strip from upstream and guide it through the gap between the upper and lower steel rollers. During this passage, the weight of the upper steel roller alone provides gentle yet effective rolling pressure to eliminate curling and internal stress.

[0060] The heating and pressing unit is located after the precision pressing and leveling unit. This unit includes multiple sets of heating rollers for receiving the precision-pressed and leveled coiled copper foil. The unit is configured to guide the coiled copper foil to undergo a first heating and pressing with a first insulating film introduced from the middle of the equipment's unloading shaft, followed by a second heating and pressing with a second insulating film, thereby encapsulating the copper foil circuitry between the two insulating films to form a three-layer composite strip.

[0061] The forming and die-cutting unit, located after the heating and pressing unit, is used to perform final shape forming and die-cutting on the cooled or semi-cured three-layer composite strip to separate independent flexible die-cut circuit board semi-finished products with preset outlines from the continuous strip.

[0062] In one possible implementation, to ensure the purity of the leveling process, the steel rollers in the precision leveling unit are not structurally connected to any drive or pressurizing device for applying pressure other than their own weight, such as cylinders, hydraulic cylinders, springs, or cam pressurizing mechanisms.

[0063] Meanwhile, to achieve the low-temperature process described above, the heating and pressing unit includes two sets of heating rollers: a first heating roller set and a second heating roller set. The first heating roller set is specifically used for the first heating and pressing of the rolled copper foil with the first insulating film. The second heating roller set is specifically used for the second heating and pressing with the second insulating film. The operating temperature of both sets of heating rollers is precisely set and maintained within the range of 150 to 180°C.

[0064] Through the aforementioned continuous production method and equipment, this invention achieves high flatness, high yield, and high efficiency in the continuous production of flexible die-cut circuit boards. For example, compared to the original process that uses high temperature and lacks a self-weight leveling step, the machine operating speed of this invention can be increased by 15% to 25%, product dimensional accuracy and surface flatness are significantly improved, and the overall die-cutting yield can be stably maintained above 99%, demonstrating significant technological advancement and industrial application value.

[0065] Specifically, this invention introduces a precision flattening process using the weight of a steel roller after die-cutting and before heating and pressing the copper foil roll. This process solves the problem in existing flexible die-cut circuit board manufacturing processes where copper foil curling and residual internal stress caused by die-cutting are not effectively eliminated, leading to poor product flatness and subsequent air bubbles or delamination during lamination. This process utilizes the uniform, stable, and pressure-free pressure generated by the steel roller's own weight to physically smooth the die-cut copper foil lines, actively eliminating initial defects. Based on this, the flattened copper foil, with its internal stress released, is then heated and pressed with an insulating film, avoiding the quality risks associated with directly laminating uneven copper foil. Through the synergistic effect of these techniques, this invention significantly improves the flatness of flexible die-cut circuit board products, reduces the bonding failure rate caused by copper foil warping, enhances the reliability of multilayer lamination, and creates the preconditions for further increasing production line operating speed.

[0066] The technical solutions provided by the embodiments of the present invention will be described and explained in detail below with reference to detailed implementation methods.

[0067] Please refer to Figure 2 This diagram illustrates a structural schematic of a continuous production equipment for flexible die-cutting circuit boards according to an embodiment of the present invention. It includes a 26-station circular die-cutting machine equipped with multiple feeding shafts, receiving shafts, cutter holders (G1-G26), heating rollers, and leveling rollers.

[0068] First, the coiled copper foil is mounted on the feeding shaft at the front end of the rotary cutter, while the carrier film is released simultaneously. The tension of the feeding shaft is set to 15~35N to ensure the copper foil strip is fed smoothly. The copper foil and carrier film are laminated at the G1 cutter holder. The speed ratio of the G1 holder is set to 0.9990~0.9999 to create slight tensile tension and ensure the stability of the lamination process.

[0069] The composite strip passes sequentially through cutter holders G2 and G3. Asynchronous linear cutters are installed on cutter holders G2 and G3, and their speed ratio is set to be synchronized with the main traction speed to precisely die-cut the copper foil circuit pattern. After die-cutting, the strip enters cutter holders G4 and G5, where an automatic waste removal mechanism removes excess copper foil waste outside the circuit pattern.

[0070] To eliminate internal material stress and copper foil edge curling issues generated during die-cutting and lamination, the strip material, after waste removal, enters stations G6 and G7. In this embodiment, stations G6 and G7 use conventional steel rollers from a rotary die-cutting machine, utilizing the weight of the rollers themselves to roll and flatten the strip material. This precision rolling and flattening process significantly improves the regularity of the copper foil lines and the flatness of the surface.

[0071] Further, the A-PI / PET composite film, with one side coated with thermosetting adhesive, is mounted on the feeding shaft at the front end of the rotary die cutter, with the tension of the feeding shaft set to 12~28N. The composite film is then asynchronously die-cut at the G8 cutter holder to form the desired local shape, with the speed ratio of the G8 holder set to 0.9990~0.9999. After die-cutting, the speed ratio of the A-PI / PET composite film is adjusted at the G9 cutter holder to synchronize with the main material strip.

[0072] Subsequently, the processed copper foil circuit layer and the A-PI / PET composite film, guided by the G9 cutter head, converge at station G10. Station G10 is a heated roller laminating station, with its machine base speed ratio set to be synchronized with the main traction speed, and the heating temperature precisely controlled between 150 and 180°C. At this temperature, the thermosetting adhesive layer on the A-PI / PET composite film is fully activated, allowing it to stably bond with the copper foil circuit layer, and simultaneously transferring the copper foil circuit from the carrier film to the A-PI / PET composite film, forming a preliminary composite layer structure.

[0073] Further, a B-PI / PET composite film with a single-sided thermosetting adhesive coating is mounted on the feed shaft at the rear end of the rotary die cutter, with the feed shaft tension set to 12~28N. This composite film undergoes asynchronous die cutting at the G13 cutter holder to form the desired local shape, with the G13 cutter speed ratio set to 0.9990~0.9999. After die cutting, the B-PI / PET composite film's speed ratio is adjusted at the G12 cutter holder to synchronize with the main feed strip.

[0074] The composite layer obtained at station G10 is joined with the B-PI / PET composite film at station G11. Station G11 is a composite station consisting of two sets of heating rollers, with a machine speed ratio set to 0.9990~0.9999 and a heating temperature precisely controlled at 150~180℃. The thermosetting adhesive layer on the B-PI / PET composite film is fully activated at this temperature, allowing it to stably adhere to the other side of the composite layer obtained in step 2 (i.e., the combination of A-PI / PET film and copper foil), forming a three-layer composite strip of A-PI / PET-copper foil-B-PI / PET.

[0075] Furthermore, the three-layer composite strip enters the G14 cutter holder, and a heating roller is simultaneously installed at the G15 cutter holder. The speed ratio of the heating roller at station G15 is set to be synchronized with the main traction, and the heating temperature is still controlled at 150~180℃. This step, by applying additional heat and pressure, performs a second high-temperature strengthening bonding of the three-layer material that has completed the initial lamination, significantly enhancing the adhesion strength between the upper and lower PI / PET composite films and the middle copper foil layer. This effectively solves the delamination problem that may be caused by insufficient pressing time or temperature, and provides a process basis for further accelerating production.

[0076] After undergoing three high-temperature strengthening bonding processes, the material strip sequentially enters the G16, G17, G18, G19, and G20 die holders. These stations are equipped with die-cutting blades to define the product outline, and the speed ratios of all machine holders are set to synchronize with the main traction. Through continuous die-cutting using multiple die holders and multiple processes, the final outline of the flexible die-cut circuit board is formed. Thanks to the quantitative control of parameters such as tension, speed ratio, and temperature in the aforementioned processes, as well as the stress leveling and strengthening bonding processes, the operating speed of the rotary die-cutting machine in this step can be increased by 15% to 25% compared to traditional processes, and the die-cutting yield can be stably maintained above 99%, achieving high-precision and high-efficiency continuous production.

[0077] The semi-finished material strip, after completing its shape formation, undergoes real-time synchronous detection of key dimensions (such as line width, line spacing, and contour accuracy) in the G21 and G22 die-cutting areas via integrated CCD (charge-coupled device) inspection equipment. After inspection, the strip enters the G23 and G24 die-cutting areas, where an integrated inkjet printer prints pass / fail markings, serial numbers, or other traceability information onto each product based on the CCD detection results. This step achieves integrated online completion of die-cutting, inspection, and printing, significantly improving production efficiency and reducing subsequent processes.

[0078] In all the above processes, to maintain the smooth operation of the conveyor belt and the consistency of material stress and tension, the corresponding feeding shafts for copper foil, A-PI / PET, B-PI / PET, and the carrier film used in each process are arranged on the corresponding feeding shafts at the front, middle, or rear of the rotary cutter machine. The tension of all carrier film feeding shafts is uniformly set to 15~35N, and the speed ratio of the cutter holders (such as G25, G26, etc.) through which the carrier film passes is consistent with the speed ratio of the corresponding main material cutter holder.

[0079] Finally, the finished product is wound up by a take-up shaft, completing the entire manufacturing process of the flexible die-cut circuit board.

[0080] In this embodiment, the preferred ranges for each key control parameter are summarized as follows: Material tension: 15~28N for copper foil, 12~28N for A-PI / PET, 12~28N for B-PI / PET, and 15~35N for carrier film.

[0081] Machine base speed ratio: Depending on the workstation function, it can be selectively set to 0.9990~0.9999 or synchronized with the main traction speed.

[0082] Heating temperature: The temperature of each heating roller composite station (G10, G11, G15) is independently controlled, and the range is 150~180℃.

[0083] It should be noted that this embodiment uses PI (polyimide) and copper foil as the main materials. However, depending on product design requirements, the PI (polyimide) in the PI / PET composite film can be replaced with flexible film materials such as PET (polyethylene terephthalate) and PC (polycarbonate); the copper foil can also be replaced with other conductive metal foils such as aluminum foil. When materials are replaced, the corresponding process parameters (such as tension and temperature) should be adaptively adjusted according to the specifications provided by the material supplier and the actual width of the material. This should be considered a simple variation of the technical solution of this invention and still falls within the protection scope of this invention.

[0084] To verify the actual effect of the above-mentioned process of the present invention, a batch production verification was carried out using the method of this embodiment (batch range 1~20), and compared with the process without steel roller fine pressing and leveling and three high temperature composite processes. The results are shown in Table 1.

[0085] Table 1. Verification data of process effect

[0086] As shown in Table 1, after using G6 and G7 steel rollers for precision pressing and leveling, the product flatness improvement rate reached 51.4%, significantly improving the product's flatness. After adopting a three-stage high-temperature composite process, the interlayer peel strength increased from 0.9 N / cm to 2.8 N / cm, and the delamination defect rate dropped to 0%, completely solving the delamination problem and verifying the necessity and superiority of the three-stage high-temperature enhanced bonding process. This invention's process generates no wastewater or waste liquid during production, and waste copper and waste film can be 100% recycled, demonstrating excellent environmental benefits.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A continuous production method for flexible die-cut circuit boards, characterized in that, Includes the following steps: The copper foil rolls are die-cut to form circuit patterns, and the die-cut copper foil rolls are automatically discharged. After the waste is discharged, the copper foil roll is passed between a pair of steel rollers arranged opposite each other. The weight of the steel rollers themselves is used to roll and press the copper foil roll to eliminate the curling and internal stress of the copper foil roll. The rolled copper foil is heated and pressed together with the first insulating film; The roll of copper foil with the first insulating film pressed on it is heated and pressed together with the second insulating film to form a three-layer composite strip; The three-layer composite strip is shaped and die-cut to obtain a flexible die-cut circuit board semi-finished product.

2. The continuous production method of flexible die-cut circuit boards according to claim 1, characterized in that, When die-cutting coiled copper foil, the tension of the feeding shaft is set to 15~35N, and the speed ratio of the feed roller is set to 0.9990~0.9999.

3. The continuous production method of flexible die-cut circuit boards according to claim 2, characterized in that, The method further includes: Before die-cutting the coiled copper foil, the coiled copper foil is laminated with a carrier film, and then the laminated material is die-cut. The tension of the feeding shaft of the carrier film is set to 15~35N, and the speed ratio of the machine base and the main material machine base is kept consistent.

4. The continuous production method of flexible die-cut circuit boards according to claim 1, characterized in that, The temperature for performing the heating and pressing is set to 150~180℃.

5. The continuous production method of flexible die-cut circuit boards according to claim 4, characterized in that, The process of heating and pressing the rolled copper foil with the first insulating film, and heating and pressing the rolled copper foil with the first insulating film with the second insulating film, are both performed at a temperature of 150~180°C.

6. The continuous production method of flexible die-cut circuit boards according to claim 5, characterized in that, After heating and pressing the rolled copper foil with the first insulating film onto the second insulating film, the process further includes: heating and pressing the formed three-layer composite strip a third time at a temperature of 150~180°C.

7. The continuous production method of flexible die-cut circuit boards according to claim 1, characterized in that, When rolling the coiled copper foil using the weight of the steel roller itself, no external pressure other than its own weight is applied to the steel roller.

8. A continuous production method for flexible die-cut circuit boards according to any one of claims 1 to 7, characterized in that, After the three-layer composite strip is shaped and die-cut, the process also includes: For the flexible die-cut circuit board semi-finished product, CCD size detection is performed simultaneously on the production line; For the semi-finished flexible die-cut circuit boards that have completed dimensional inspection, marking and printing are performed simultaneously on the production line.

9. A continuous production equipment for flexible die-cut circuit boards, characterized in that, include: The die-cutting and waste removal unit is used to die-cut coil copper foil to form circuit patterns and automatically remove waste from the die-cut coil copper foil. The precision pressing and leveling unit is located after the die-cutting waste removal unit and includes a pair of steel rollers arranged opposite each other. The precision pressing and leveling unit is configured to pass the waste-removed coiled copper foil between the pair of steel rollers arranged opposite each other, and to roll the coiled copper foil by relying on the weight of the steel rollers themselves to eliminate the curling and internal stress of the coiled copper foil. The heating and pressing unit is located after the precision pressing and leveling unit. It is used to heat and press the rolled copper foil with the first insulating film and the second insulating film in sequence to form a three-layer composite strip. The forming and die-cutting unit is located after the heating and pressing unit and is used to perform shape forming and die-cutting on the three-layer composite strip to obtain a flexible die-cut circuit board semi-finished product.

10. The continuous production equipment according to claim 9, characterized in that, The steel rollers of the precision leveling unit are not connected to any drive or pressurizing device for applying pressure other than their own weight. The heating and pressing unit includes two sets of heating rollers, which are used for the first heating and pressing of the rolled copper foil with the first insulating film and the second heating and pressing with the second insulating film, respectively. The temperature of the heating rollers is set to 150~180℃.

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