Uncovering and stripping method for flexible base material

Abstract

The invention belongs to the technical field of multi-layer flexible circuit boards, and discloses an uncovering and stripping method of a flexible base material, which comprises the following steps of: determining the geometric configuration of a copper layer in an uncovering area and optimizing parameters of the copper layer through circuit manufacturing graphic design, and reserving the copper layer as a reinforcing structure in the uncovering area; determining pattern transfer parameters, setting a negative pattern in an uncovering area, and protecting a copper layer in the area during exposure; carrying out secondary etching verification through AOI detection on the dimensional tolerance of a copper layer area; according to the method, punching-1 process parameters are determined, PI is torn, stripped and uncovered in an uncovering process by utilizing the mechanical difference between a copper layer and PI, and tearing force is fed back through a force sensor and real-time monitoring is carried out. The strength and integrity of the uncovering area are enhanced by designing and reserving the copper surface, the uncovering area is directly torn, stripped and uncovered by utilizing the tearable characteristic of polyimide, and the copper surface area is reserved to ensure that the waste obtained by tearing is complete and does not remain, so that the uncovering of the soft board is effectively realized, the product quality risk is reduced, and the laser cutting cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of multi-layer flexible circuit boards, and in particular relates to a method for uncovering and peeling a flexible substrate. Background Art

[0002] In multi-layer flexible circuit boards, different areas require different board thicknesses. This necessitates a layered design for the outer flexible board in the thin-board area, and a process for removing the cover during the outer layer manufacturing process. The existing process flow design utilizes laser cutting for the removal of the cover. This laser-controlled depth-cutting removal technology follows the laser cutting process used for rigid-flex boards. For the removal of the cover of multi-layer flexible circuit board products, the material to be cut is polyimide (PI). When the polyimide being cut is ultra-thin (0.012-0.05mm), laser cutting easily cuts through the removal layer and damages the board surface in the effective area of ​​the flexible board.

[0003] The disadvantages of this laser cutting polyimide PI production process are:

[0004] 1. PI depth control cutting is difficult: The thickness of the polyimide PI layer of the flexible circuit board is generally designed to be 0.012mm, 0.025mm, and 0.050mm. The thickness is very small, and laser depth control cutting is very difficult. It is easy to cut through the polyimide layer and cause damage to the inner layer of the flexible board;

[0005] 2. Laser cutting is expensive: Laser cutting requires low energy and multiple cuts, resulting in low production efficiency and high costs. Therefore, a new method for peeling off flexible substrates is urgently needed.

[0006] Through the above analysis, the problems and defects of the existing technology are: in the current laser cutting polyimide PI production process, PI controlled depth cutting is difficult and the laser cutting cost is high. Summary of the Invention

[0007] To overcome the problems existing in the related art, the present invention discloses an embodiment that provides a method for peeling off a flexible substrate. The technical solution is as follows:

[0008] The present invention is achieved in that a method for peeling a flexible substrate comprises the following steps:

[0009] S1, copper layer pattern design in the uncovering area: through circuit production pattern design, determine the geometric configuration of the copper layer in the uncovering area and optimize the copper layer parameters, retaining the copper layer in the uncovering area as a reinforcement structure;

[0010] S2, circuit fabrication process control: determine pattern transfer parameters, set a negative pattern in the uncovered area, and protect the copper layer in this area during exposure; use AOI to detect the dimensional tolerance of the copper layer area and perform secondary etching verification;

[0011] S3, lid-off process control: Determine the punching-1 process parameters, use the mechanical difference between the copper layer and the PI to tear and peel off the PI during the lid-off process, and use the force sensor to feedback the tearing force and perform real-time monitoring.

[0012] In step S1, the copper layer in the uncovering area is designed to be a grid type or a finger array type, with a grid opening rate of 30-70%, a copper grid spacing of 0.2-0.5mm, and a line width of 50-100μm; the finger copper strips are 80-150μm wide, with a spacing of 0.3-0.8mm, and the ends are designed to be arc-shaped with an arc radius R ≥ 30μm; a copper frame is added to the boundary of the uncovering area, with a copper frame width ≥ 200μm, and the internal copper pattern maintains a gap of 100-150μm from the boundary.

[0013] In step S1, optimizing the copper layer parameters includes:

[0014] The thickness of the copper layer is 5-18μm; the ratio of copper foil thickness to PI thickness is controlled at 1:3-1:5;

[0015] The uncovered area and the non-uncovered area adopt a gradient copper thickness change, and the transition length is ≥1mm.

[0016] In step S2, the graphic transfer parameters include:

[0017] Dry film attachment: Use 20-25μm thick anti-etching dry film, attaching pressure 0.3-0.5MPa, temperature 50±5℃;

[0018] Exposure control: LDI exposure machine, wavelength 405nm, energy setting 80-120mJ / cm 2 , resolution ≤ 10 μm;

[0019] Etching parameters: The acidic etching solution is CuCl2 / HCl, the etching rate is controlled at 1.5-2.0μm / min, and the side etching amount is ≤5μm.

[0020] In step S3, the punching-1 process parameter control includes:

[0021] Use a stepped punch with a cutting depth of 70-80% of the total thickness; offset the punching by 50 μm along the outer contour of the uncovering area, and retain 2-3 0.5 mm wide connecting bridges.

[0022] Furthermore, the punching depth control process includes:

[0023] The dynamic compensation algorithm for punching depth is:

[0024] D actual =D nom +α(T-25)+β(H-50)

[0025] Where D actual is the actual punching depth; D nom is the nominal punching depth; T is the ambient temperature, set to 20-30°C; H is the ambient relative humidity, set to 40-60%RH; α is the temperature compensation coefficient, set to 0.018-0.022μm / °C; β is the humidity compensation coefficient, set to 0.12-0.18μm / %RH.

[0026] When |T-25|>3℃ or |H-50|>10%RH is detected, α / β will be automatically switched to the backup parameters and the warning signal will be triggered to achieve dynamic adjustment. The backup parameters α'=0.025, β'=0.12;

[0027] D after receiving compensation actual Value, adjust the servo motor stroke through the PID controller;

[0028]

[0029] Where u(k) is the output of the kth control cycle, which is used to represent the total control quantity calculated by PID and sent to the servo motor; e(k) is the current error, which is used to represent the difference between the set value and the actual measured value. e(k) = D actual -D measured ;T s is the control period, which is used to indicate the interval between two PID calculations; K p is the proportional gain, which is used to express the linear proportional relationship between the control output and the current error; K i is the integral gain, which is used to express the relationship between the control output and the error accumulation; K d is the differential gain, which is used to express the relationship between the control output and the error change rate; ∑e(j) is the historical error, which is used to express the cumulative sum of all errors from the beginning to the current moment; is the error change rate, which is used to express the difference between the current error and the previous error.

[0030] EtherCAT bus communication is used with a cycle of 1ms; the servo stamping system response time is ≤5ms, the servo drive speed loop bandwidth is ≥500Hz, and the position repeatability is ±2μm.

[0031] In step S3, the tearing and peeling dynamics control process includes:

[0032] The waste area is clamped by a robot, and the cover is peeled off at a constant speed of 0-50mm / s and an angle of 20-35°;

[0033] A V-shaped notch with a depth of 30-50 μm is preset at the edge of the uncovering area to guide the tearing direction;

[0034] A dynamic model of tearing force is constructed, and the tearing force is fed back through a force sensor, triggering shutdown when the limit is exceeded.

[0035] Furthermore, in the process of regulating the copper-PI bonding strength, the following steps are also included:

[0036] Use plasma for pre-treatment cleaning, with an Ar / O2 mixing ratio of 4:1-3:1, a power of 300-350W, a processing time of 90-120s, and a bonding force window of 4-6N / cm;

[0037] Select a modified acrylic film with a melt index of 8-12g / 10min and a bonding temperature of 200℃; use a stepwise curing method at 80℃, 120℃, and 160℃ for 30min each, with a thickness tolerance of ±3μm after curing;

[0038] A high-precision CCD vision system is used for multi-layer alignment with an accuracy of ≤25μm, and the mechanical positioning of tool hole pins is combined to achieve laminate structure optimization.

[0039] Furthermore, the tearing force dynamic model is:

[0040]

[0041] Where, F tear (t) is the real-time tearing force, δ(t) is the deformation of the PI layer, which is calculated by the encoder displacement difference; η is the damping coefficient of the PI material; E is the PI elastic modulus; and k is the geometric factor.

[0042] The logic formula for over-limit judgment is:

[0043]

[0044] Where, F filtered is the tearing force after filtering, F limit is the dynamic force threshold, dF / dt is the force change rate threshold, F filtered >F limit Indicates that the safety threshold is continuously exceeded. The power of expression increases sharply.

[0045] Furthermore, the calculation formula of the critical tearing force is:

[0046] F c =k·(σ PI ·t PI +σ Cu ·t Cu ·A R )

[0047] Where k is the geometric factor, which is set to 0.8-1.2; σ PI is the PI strength; σ Cuis the strength of the copper layer; t PI is the thickness of PI; t Cu is the thickness of the copper layer; A R is the copper surface retention rate.

[0048] The optimal parameter interval is set to: when 0.3≤A R When ≤0.6, the tearing force is controlled at 5-15N / mm.

[0049] In combination with all the above technical solutions, the beneficial effects of the present invention are as follows:

[0050] First, the present invention's flexible substrate peeling method enhances the strength and integrity of the peeling area by retaining the copper surface. It also leverages the tearability of polyimide to allow for direct peeling and peeling. By leveraging the easy-to-tear nature of polyimide and preserving the copper surface area, the peeled material remains intact, eliminating any residual waste. This method effectively removes the surface of the flexible substrate, reduces product quality risks, and reduces laser cutting costs.

[0051] By precisely matching the stress concentration design of the copper retention pattern with tearing dynamics, as well as accurately calibrating the temperature / humidity coefficients and matching them with the servo system's rapid response, this solution controls the punching depth fluctuation to within ±1.5μm (compared to ±5μm in the original process), significantly improving the yield rate of the uncapping process. Field measurements have shown that this solution can achieve an edge uniformity of ≤50μm and a yield rate of ≥98.5%, while saving approximately 65% ​​energy compared to the laser uncapping process.

[0052] Second, this invention preserves the copper surface in the uncovering area through circuit pattern design, allowing efficient uncovering by directly tearing the PI during the uncovering process. Through coordinated optimization of materials, structure, and process, this invention transforms traditional passive removal into a controllable tearing mechanism. Compared to traditional laser ablation uncovering technology, this technology can reduce costs by approximately 40% and increase production efficiency by over 30%, making it particularly suitable for applications in high-frequency flexible electronic packaging.

[0053] Third, compared to traditional laser ablation decapping processes, this invention saves equipment investment (no laser system required) and energy consumption (reduced by approximately 65%), reducing single-piece processing costs by over 40%. It also reduces material loss (increasing copper / PI utilization by 30%) and is suitable for mass production of high-frequency flexible circuit boards. The annual output value is expected to reach 500-800 million yuan (based on an annual production capacity of 100,000 square meters).

[0054] This invention meets the precise cover requirements of 5G / 6G high-frequency flexible circuit boards (FPCs), seizing the high-end electronic packaging market (such as foldable screen mobile phones and satellite communication equipment). It can also be expanded to fields such as medical flexible sensors and aerospace flexible antennas, with a potential market size exceeding 2 billion yuan per year.

[0055] Fourth, the present invention proposes for the first time a composite uncovering method of "copper layer retention + controlled tearing", which breaks through the limitations of traditional purely mechanical or purely laser processes and solves the contradiction between the strength and precision of the uncovering area when multiple layers of flexible boards are stacked.

[0056] No similar solutions were found in international patent searches. The specific innovation comparison is shown in Table 1.

[0057] Table 1 Comparison of the innovation of the present invention and the existing solutions

[0058]

[0059] Fifth, the present invention solves the following technical problems:

[0060] Problem 1: Flexible materials are prone to delamination when peeling (the industry typically reduces efficiency to ensure quality). The copper layer retention design of the present invention provides mechanical support and a controlled tear angle (20-35°) allows for clean peeling.

[0061] Problem 2: Ultra-thin multilayer boards (<100μm) are prone to breakage when the cover is removed. This invention utilizes dynamic punching depth compensation (±1.5μm) in conjunction with PID servo control to adapt to thickness fluctuations.

[0062] The parameter robustness of the present invention (CPK≥1.67) was confirmed by 3σ process window analysis.

[0063] Sixth, while conventional wisdom holds that a retained copper layer hinders removal, this invention demonstrates that a specific copper pattern (grid / finger) can guide the tear path. Conventional wisdom holds that PI tearing inevitably leads to burrs, this invention achieves a clean fracture (roughness <1μm) through a V-notch stress concentration design. Furthermore, this invention transforms a material defect (PI's low tear strength) into a process advantage, pioneering a new process path through reverse thinking. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure;

[0065] Figure 1 This is a flow chart of a method for peeling a flexible substrate provided by an embodiment of the present invention;

[0066] Figure 2 1 is a front-sectional schematic diagram of a multi-layer flexible board provided by an embodiment of the present invention after the cover is removed;

[0067] Figure 3 This is a cross-sectional schematic diagram of a multi-layer flexible board after the cover is removed provided by an embodiment of the present invention;

[0068] Figure 4 is a top view of the adhesive film layer provided by an embodiment of the present invention;

[0069] Figure 5 is a top view of the first circuit layer provided by an embodiment of the present invention;

[0070] Figure 6 This is a top view of the outer layer "punching-1" of the L0104 layer provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0071] To make the above-mentioned objects, features, and advantages of the present invention more readily apparent, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description sets forth numerous specific details to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art may make similar modifications without departing from the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0072] Example 1, as Figure 1 As shown, the method for peeling off the flexible substrate provided by the embodiment of the present invention specifically includes the following steps:

[0073] S1, copper layer pattern design in the uncovering area: through circuit production pattern design, determine the geometric configuration of the copper layer in the uncovering area and optimize the copper layer parameters, retaining the copper layer in the uncovering area as a reinforcement structure;

[0074] S2, circuit fabrication process control: determine pattern transfer parameters, set a negative pattern in the uncovered area, and protect the copper layer in this area during exposure; use AOI to detect the dimensional tolerance of the copper layer area and perform secondary etching verification;

[0075] S3, lid-off process control: Determine the punching-1 process parameters, use the mechanical difference between the copper layer and the PI to tear and peel off the PI during the lid-off process, and use the force sensor to feedback the tearing force and perform real-time monitoring.

[0076] The copper layer design of the uncovering area provided in the embodiment of the present invention is a grid type or a finger array type, the grid opening rate is 30-70%, the copper grid spacing is 0.2-0.5mm, and the line width is 50-100μm; the finger copper strips are 80-150μm wide, the spacing is 0.3-0.8mm, the ends are designed to be arc-shaped, and the arc radius R ≥ 30μm; a copper frame is added to the boundary of the uncovering area, the copper frame width is ≥ 200μm, and the internal copper pattern maintains a gap of 100-150μm from the boundary.

[0077] The embodiment of the present invention optimizes the copper layer parameters including: the copper layer thickness is 5-18 μm; the ratio of copper foil thickness to PI thickness is controlled at 1:3-1:5; the uncovered area and the uncovered area adopt a gradient copper thickness change, and the transition length is ≥1 mm.

[0078] The graphics transfer parameters provided by the embodiment of the present invention include:

[0079] Dry film attachment: Use 20-25μm thick anti-etching dry film, attaching pressure 0.3-0.5MPa, temperature 50±5℃;

[0080] Exposure control: LDI exposure machine, wavelength 405nm, energy setting 80-120mJ / cm 2 , resolution ≤ 10 μm;

[0081] Etching parameters: The acidic etching solution is CuCl2 / HCl, the etching rate is controlled at 1.5-2.0μm / min, and the side etching amount is ≤5μm.

[0082] The punching-1 process parameter control provided by the embodiment of the present invention includes:

[0083] Use a stepped punch with a cutting depth of 70-80% of the total thickness; offset the punching by 50 μm along the outer contour of the uncovering area, and retain 2-3 0.5 mm wide connecting bridges.

[0084] The punching depth control process provided by the embodiment of the present invention includes:

[0085] The dynamic compensation algorithm for punching depth is:

[0086] D actual =D nom +α(T-25)+β(H-50)

[0087] Where D actual is the actual punching depth; D nom is the nominal punching depth; T is the ambient temperature, set to 20-30°C; H is the ambient relative humidity, set to 40-60%RH; α is the temperature compensation coefficient, set to 0.018-0.022μm / °C; β is the humidity compensation coefficient, set to 0.12-0.18μm / %RH.

[0088] When |T-25|>3℃ or |H-50|>10%RH is detected, α / β will be automatically switched to the backup parameters and the warning signal will be triggered to achieve dynamic adjustment. The backup parameters α'=0.025, β'=0.12;

[0089] D after receiving compensation actual Value, adjust the servo motor stroke through the PID controller;

[0090]

[0091] Where u(k) is the output of the kth control cycle, which is used to represent the total control quantity calculated by PID and sent to the servo motor; e(k) is the current error, which is used to represent the difference between the set value and the actual measured value. e(k) = D actual -D measured ;T s is the control period, which is used to indicate the interval between two PID calculations; K p is the proportional gain, which is used to express the linear proportional relationship between the control output and the current error; K i is the integral gain, which is used to express the relationship between the control output and the error accumulation; K d is the differential gain, which is used to express the relationship between the control output and the error change rate; ∑e(j) is the historical error, which is used to express the cumulative sum of all errors from the beginning to the current moment; is the error change rate, which is used to express the difference between the current error and the previous error.

[0092] EtherCAT bus communication is used with a cycle of 1ms; the servo stamping system response time is ≤5ms, the servo drive speed loop bandwidth is ≥500Hz, and the position repeatability is ±2μm.

[0093] The tearing and peeling dynamics control process provided by the embodiment of the present invention includes:

[0094] The waste area is clamped by a robot, and the cover is peeled off at a constant speed of 0-50mm / s and an angle of 20-35°;

[0095] A V-shaped notch with a depth of 30-50 μm is preset at the edge of the uncovering area to guide the tearing direction;

[0096] A dynamic model of tearing force is constructed, and the tearing force is fed back through a force sensor, triggering shutdown when the limit is exceeded.

[0097] The embodiment of the present invention further includes, during the copper-PI bonding strength regulation process:

[0098] Use plasma for pre-treatment cleaning, with an Ar / O2 mixing ratio of 4:1-3:1, a power of 300-350W, a processing time of 90-120s, and a bonding force window of 4-6N / cm;

[0099] Select a modified acrylic film with a melt index of 8-12g / 10min and a bonding temperature of 200℃; use a stepwise curing method at 80℃, 120℃, and 160℃ for 30min each, with a thickness tolerance of ±3μm after curing;

[0100] A high-precision CCD vision system is used for multi-layer alignment with an accuracy of ≤25μm, and the mechanical positioning of tool hole pins is combined to achieve laminate structure optimization.

[0101] The tearing force dynamic model provided by the embodiment of the present invention is:

[0102]

[0103] Where, F tear (t) is the real-time tearing force, δ(t) is the deformation of the PI layer, which is calculated by the encoder displacement difference; η is the damping coefficient of the PI material; E is the PI elastic modulus; and k is the geometric factor.

[0104] The logic formula for over-limit judgment is:

[0105]

[0106] Where, F filtered is the tearing force after filtering, F limit is the dynamic force threshold, dF / dt is the force change rate threshold, F filtered >F limit Indicates that the safety threshold is continuously exceeded. The power of expression increases sharply.

[0107] The calculation formula of the critical tearing force provided by the embodiment of the present invention is:

[0108] F c =k·(σ PI ·t PI +σ Cu ·t Cu ·A R )

[0109] Where k is the geometric factor, which is set to 0.8-1.2; σ PI is the PI strength; σ Cu is the strength of the copper layer; t PI is the thickness of PI; t Cu is the thickness of the copper layer; A R is the copper surface retention rate.

[0110] The optimal parameter interval is set to: when 0.3≤A R When ≤0.6, the tearing force is controlled at 5-15N / mm.

[0111] Example 2, taking a simple 4-layer flexible board structure product as an example (such as Figure 2 、 3 product structure), the scope of the present invention includes but is not limited to the simplified graphics shown.

[0112] 1. L02 / 03 layer process: cutting, drilling, black hole, electroplating, pre-treatment, circuit production, chemical cleaning, laminating cover film, pressing, curing, plasma cleaning, and preparing multi-layer combination after completing the above processes;

[0113] 2. Adhesive film production process: cutting, laser cutting, and preparing multi-layer assembly after completion;

[0114] 3. L01 layer and L04 layer process: cutting and drilling, and then preparing for multi-layer combination;

[0115] 4. Multi-layer assembly process: L0203 layer alignment pre-lamination adhesive film layer, such as Figure 4 As shown, pre-pressing; L01 layer + L02 / 03 layer + L04 layer alignment, pre-soldering, pressing, after completing the above process, the L0104 4-layer flexible board combination is produced; Among them, the film is pre-laminated, and multiple combinations are used to align and laminate using drilled tool holes; pressing uses pressure transmission to ensure product flatness;

[0116] 5. L0104 layer process: punching, board edge punching, surface cleaning and debonding, drilling, plasma debonding, black hole, electroplating, circuit production, chemical cleaning, cover film application, fast pressing, curing, pre-treatment, solder mask production, curing, pre-treatment, surface treatment, slicing and punching, punching-1, peeling and uncovering, punching-2, electrical testing, cleaning, appearance inspection, packaging, and warehousing;

[0117] 6. Circuit production process, such as Figure 5 As shown, the surface copper is retained in the uncovered area;

[0118] 7. Punching-1 process, such as Figure 6 As shown, the connection between the cover-opening area and the frame is cut off in the waste area, so that the cover can be peeled off in layers in the waste area and the waste can be torn off.

[0119] Example 3, 4-layer flexible board cover (total thickness 120μm) application scenario

[0120] Nominal value setting: Dnom = 0.7 × 120 = 84 μm (cut into 70% thickness);

[0121] Real-time environmental monitoring: T = 28 ° C, H = 45;

[0122] Compensation calculation: D actual =84+0.02×(28-25)+0.15×(45-50)

[0123] =84+0.06-0.75

[0124] =83.31μm;

[0125] Implementation effect: The actual cutting depth is 83.3μm (after compensation), ensuring the remaining PI layer thickness is 36.7μm (original design 36μm), with an error of <2%.

[0126] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0127] The above description is only a preferred specific implementation method of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with this technical field within the technical scope disclosed by the present invention and within the spirit and principles of the present invention should be covered by the scope of protection of the present invention.

Claims

1. A method for peeling a flexible substrate, characterized in that: The method comprises the following steps: S1, copper layer pattern design in the uncovering area: through circuit production pattern design, determine the geometric configuration of the copper layer in the uncovering area and optimize the copper layer parameters, retaining the copper layer in the uncovering area as a reinforcement structure; S2, circuit fabrication process control: determine pattern transfer parameters, set a negative pattern in the uncovered area, and protect the copper layer in this area during exposure; use AOI to detect the dimensional tolerance of the copper layer area and perform secondary etching verification; S3, lid-off process control: Determine the punching-1 process parameters, use the mechanical difference between the copper layer and the PI to tear and peel off the PI during the lid-off process, and use the force sensor to feedback the tearing force and perform real-time monitoring.

2. The method for peeling a flexible substrate according to claim 1, wherein: In step S1, the copper layer in the uncovering area is designed to be a grid type or a finger array type, with a grid opening rate of 30-70%, a copper grid spacing of 0.2-0.5mm, and a line width of 50-100μm; the finger copper strips are 80-150μm wide, with a spacing of 0.3-0.8mm, and the ends are designed to be arc-shaped with an arc radius R ≥ 30μm; a copper frame is added to the boundary of the uncovering area, with a copper frame width ≥ 200μm, and the internal copper pattern maintains a gap of 100-150μm from the boundary.

3. The method for peeling off a flexible substrate according to claim 1, wherein: In step S1 , the copper layer parameters are optimized, including: the copper layer thickness is 5-18 μm; the ratio of copper foil thickness to PI thickness is controlled at 1:3-1:5; the uncovered area and the uncovered area adopt a gradient copper thickness change, and the transition length is ≥1 mm.

4. The method for peeling off a flexible substrate according to claim 1, wherein: In step S2, the graphic transfer parameters include: Dry film attachment: Use 20-25μm thick anti-etching dry film, attaching pressure 0.3-0.5MPa, temperature 50±5℃; Exposure control: LDI exposure machine, wavelength 405nm, energy setting 80-120mJ / cm 2 , resolution ≤ 10 μm; Etching parameters: The acidic etching solution is CuCl2 / HCl, the etching rate is controlled at 1.5-2.0μm / min, and the side etching amount is ≤5μm.

5. The method for peeling off a flexible substrate according to claim 1, wherein: In step S3, the punching-1 process parameter control includes: using a stepped punching tool with a cutting depth of 70-80% of the total thickness; punching along the outer contour of the uncovering area with a 50 μm offset, and retaining 2-3 0.5 mm wide connecting bridges.

6. The method for peeling off a flexible substrate according to claim 5, wherein: The punching depth control process includes: The dynamic compensation algorithm for punching depth is: D actual =D nom +α(T-25)+β(H-50) Where D actual is the actual punching depth; D nom is the nominal punching depth; T is the ambient temperature, set to 20-30°C; H is the ambient relative humidity, set to 40-60%RH; α is the temperature compensation coefficient, set to 0.018-0.022μm / °C; β is the humidity compensation coefficient, set to 0.12-0.18μm / %RH; When |T-25|>3℃ or |H-50|>10%RH is detected, α / β will be automatically switched to the backup parameters and the warning signal will be triggered to achieve dynamic adjustment. The backup parameters α'=0.025, β'=0.12; D after receiving compensation actual Value, adjust the servo motor stroke through the PID controller; Where u(k) is the output of the kth control cycle, which is used to represent the total control quantity calculated by PID and sent to the servo motor; e(k) is the current error, which is used to represent the difference between the set value and the actual measured value. e(k) = D actual -D measured ;T s is the control period, which is used to indicate the interval between two PID calculations; K p is the proportional gain, which is used to express the linear proportional relationship between the control output and the current error; K i is the integral gain, which is used to express the relationship between the control output and the error accumulation; K d is the differential gain, which is used to express the relationship between the control output and the error change rate; ∑e(j) is the historical error, which is used to express the cumulative sum of all errors from the beginning to the current moment; is the error change rate, which is used to express the difference between the current error and the previous error; EtherCAT bus communication is used with a cycle of 1ms; the servo stamping system response time is ≤5ms, the servo drive speed loop bandwidth is ≥500Hz, and the position repeatability is ±2μm.

7. The method for peeling off a flexible substrate according to claim 1, wherein: In step S3, the tearing and peeling dynamics control process includes: The waste area is clamped by a robot, and the cover is peeled off at a constant speed of 0-50mm / s and an angle of 20-35°; A V-shaped notch with a depth of 30-50 μm is preset at the edge of the uncovering area to guide the tearing direction; A dynamic model of tearing force is constructed, and the tearing force is fed back through a force sensor, triggering shutdown when the limit is exceeded.

8. The method for peeling off a flexible substrate according to claim 7, wherein: The process of regulating the copper-PI bonding strength also includes: Use plasma for pre-treatment cleaning, with an Ar / O2 mixing ratio of 4:1-3:1, a power of 300-350W, a processing time of 90-120s, and a bonding force window of 4-6N / cm; Select a modified acrylic film with a melt index of 8-12g / 10min and a bonding temperature of 200℃; use a stepwise curing method at 80℃, 120℃, and 160℃ for 30min each, with a thickness tolerance of ±3μm after curing; A high-precision CCD vision system is used for multi-layer alignment with an accuracy of ≤25μm, and the mechanical positioning of tool hole pins is combined to achieve laminate structure optimization.

9. The method for peeling off a flexible substrate according to claim 7, wherein: The tearing force dynamic model is: Where, F tear (t) is the real-time tearing force, δ(t) is the deformation of the PI layer, which is calculated by the encoder displacement difference; η is the damping coefficient of the PI material; E is the PI elastic modulus; k is the geometric factor; The logic formula for over-limit judgment is: Where, F filtered is the tearing force after filtering, F limit is the dynamic force threshold, dF / dt is the force change rate threshold, F filtered >F limit Indicates that the safety threshold is continuously exceeded. The power of expression increases sharply.

10. The method for peeling off a flexible substrate according to claim 7, wherein: The calculation formula of critical tearing force is: F c =k·(σ PI ·t PI +s Cu ·t Cu ·A R ) Where k is the geometric factor, which is set to 0.8-1.2; σ PI is the PI strength; σ Cu is the strength of the copper layer; t PI is the thickness of PI; t Cu is the thickness of the copper layer; A R is the copper surface retention rate; The optimal parameter interval is set to: when 0.3≤A R When ≤0.6, the tearing force is controlled at 5-15N / mm.

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