A polytetrafluoroethylene composite rolled copper foil and a method for manufacturing the same

Abstract

The application discloses a kind of polytetrafluoroethylene composite calendered copper foil and its manufacturing method.The method is under the condition that total cold rolling reduction rate is greater than or equal to 99%, in the interval of cumulative reduction rate greater than or equal to 40% after cold rolling, continuous differential rolling is carried out, so that the linear velocity ratio Vs of upper and lower work rolls is 1.20-1.30; and under the condition of inhibiting complete recrystallization, the copper foil is subjected to sectional annealing treatment, so that the recrystallization volume fraction of the calendered copper foil substrate is less than or equal to 15%, and a fibrous elongated grain structure continuously distributed along the rolling direction is formed, and the aspect ratio AR of the grain is greater than or equal to 24. On this basis, a polytetrafluoroethylene (PTFE) layer is combined with one side of the calendered copper foil substrate to obtain a polytetrafluoroethylene composite calendered copper foil. The composite calendered copper foil has good interface bonding stability and folding resistance reliability under repeated bending, vibration and thermal cycling conditions, and is suitable for high-speed cable electromagnetic shielding and other applications.

Description

Technical Field

[0001] This invention relates to a method for manufacturing polytetrafluoroethylene (PTFE) composite rolled copper foil, which is formed by the coordinated control of high total reduction rate cold rolling, continuous differential speed rolling in the later stage, and segmented annealing to suppress complete recrystallization. This method achieves the goal of suppressing crack initiation in the folded and overlapping areas of the metal foil during high-speed wrapping without reducing the wrapping line speed or increasing the metal foil thickness. It is mainly used for the production of rolled copper foil for 224G and 448G high-speed cables and belongs to the field of high-speed data transmission composite metal foil material technology. Background Technology

[0002] Existing composite copper foils typically use ordinary rolled copper foil or electrolytic copper foil as the substrate, which is then laminated with PTFE film through bonding, lamination, or other methods. However, the grain structure of existing copper foil substrates is mostly equiaxed or discontinuous elongated grain structure, and their microstructure does not have long-range continuity in the rolling direction, with a large number of transverse grain boundaries.

[0003] Under these structural conditions, when the composite copper foil is subjected to repeated bending, vibration, or thermal cycling loads during service, stress tends to concentrate at the transverse grain boundaries and composite interface, leading to crack initiation and propagation along short paths, which in turn causes copper foil fatigue failure or PTFE layer interface delamination. These problems are particularly pronounced under ultra-thin conditions with a thickness of less than 20 μm.

[0004] Existing technologies primarily improve interfacial adhesion by increasing the strength of the adhesive layer or modifying surface treatment methods, but they do not pay sufficient attention to the relationship between the grain structure of the copper foil substrate and the service orientation of the composite structure. Therefore, it is still necessary to provide a polytetrafluoroethylene composite rolled copper foil that is more coordinated with the actual service stress direction at the microstructure level and can improve the stability of the PTFE composite interface. Summary of the Invention

[0005] Design Objective: To address the problem of insufficient interfacial stability and decreased structural reliability in existing technologies where ordinary rolled copper foil or electrolytic copper foil is laminated with PTFE under repeated bending, vibration, and thermal cycling conditions, this invention provides a polytetrafluoroethylene (PTFE) composite rolled copper foil and its manufacturing method. This technical solution constructs a continuously distributed fibrous elongated grain structure along the rolling direction in the rolled copper foil substrate, and then laminates it with PTFE, resulting in a composite rolled copper foil with better flexural strength, interfacial bonding stability, and structural integrity.

[0006] Design scheme: To achieve the above objectives, the present invention adopts the following technical approach: First, a fibrous elongated grain structure continuously distributed along the rolling direction is constructed inside the copper foil through a specific plastic processing path, and then a PTFE layer is laminated onto the surface of the rolled copper foil substrate to obtain a composite structure with good interfacial bonding stability.

[0007] I. Manufacturing of rolled copper foil with continuous fibrous grain structure: To form a fibrous elongated grain structure that is continuously distributed along the rolling direction, this invention adopts a synergistic process path of "high total reduction cold rolling + continuous differential rolling in the later stage of cold rolling + segmented annealing to suppress complete recrystallization".

[0008] The total cold rolling reduction rate is ≥99%; differential rolling is arranged within the range of cumulative reduction rate ≥40% in the later stage of cold rolling, and preferably continuously covers the main passes of the range, with the upper and lower work roll linear speed ratio Vs being 1.20-1.30; segmented annealing is used to restore some plasticity while suppressing complete recrystallization, so that the recrystallization volume fraction of the rolled copper foil substrate is ≤15%. Under the above process conditions, the obtained rolled copper foil substrate can form a fibrous elongated grain structure continuously distributed along the rolling direction, and the grain aspect ratio AR ≥24.

[0009] 1. Under high total reduction ratio conditions, by arranging differential rolling in the later stage of cold rolling, the material can obtain a strain state different from that of conventional symmetrical rolling during subsequent rolling processes, which is beneficial for further elongation and orientation of grains along the rolling direction. Simultaneously, by controlling the degree of recrystallization through segmented annealing, the material can maintain certain work hardening characteristics while avoiding significant complete recrystallization, thus helping to preserve the formed fibrous elongated grain structure. Through the synergy of these processes, the resulting rolled copper foil substrate can achieve an AR ≥ 24.

[0010] 2. Since the grain structure of rolled copper foil exhibits a continuous fibrous distribution along the rolling direction, the "fibrous elongated grain structure continuously distributed along the rolling direction" referred to in this invention means that the grains are directionally elongated along the rolling direction, forming a continuous band-like region extending along the rolling direction. Compared to conventional equiaxed or discontinuous elongated grain structures, the number of transverse grain boundaries in this structure is reduced, and the continuity of the microstructure is improved. This structure is beneficial for improving the structural stability of the rolled copper foil substrate under repeated bending, vibration, and thermal cycling conditions, and is also beneficial for maintaining the interfacial bonding state after composite bonding.

[0011] 1) It helps to improve the structural stability of rolled copper foil substrate under repeated bending conditions.

[0012] 2) It helps to maintain the structural integrity of copper foil under relatively thin conditions.

[0013] 3) It helps improve the service stability when used as an electromagnetic shielding layer.

[0014] 4) It can work together with higher dislocation density and rolling texture to balance structural stability and processing adaptability while suppressing complete recrystallization.

[0015] 3. Explanation of the formation of continuous fibrous grain structure: Under the process conditions of this invention, the combined effects of high total reduction cold rolling, continuous differential rolling in the later stage, and segmented annealing allow the microstructure of the rolled copper foil substrate to be further elongated along the rolling direction while maintaining high continuity. Compared with conventional symmetrical cold rolling, continuous differential rolling in the later stage is more conducive to the development of grain orientation and morphology along the rolling direction; segmented annealing is used to control the degree of recrystallization, ensuring that the elongated structure is not destroyed by obvious complete recrystallization.

[0016] It should be noted that the above description of the microstructure evolution is used to help understand the technical solution of the present invention and does not constitute a limitation on the crystallographic mechanism. The key to the present invention is that, under the defined process window, the obtained rolled copper foil substrate has a recrystallization volume fraction ≤15%, a grain aspect ratio AR ≥24, and forms a fibrous elongated grain structure continuously distributed along the rolling direction.

[0017] Existing technologies mainly improve the reduction rate through symmetrical cold rolling. The deformation mode is still dominated by plane strain. Even under higher reduction rate conditions, the grains may split or undergo sufficient recrystallization during annealing, making it difficult to stably form a continuous fibrous grain structure along the rolling direction in the finished copper foil.

[0018] 4. Explanation related to application scenarios: In high-speed cable applications, materials are typically subjected to micro-bending, vibration, and thermal cycling loads along the cable's length. Because the grains in the rolled copper foil substrate of this invention are continuously elongated along the rolling direction, which corresponds to the cable's length in application, this microstructure is beneficial for improving the material's structural stability under relevant service conditions. Further composite structures with good interfacial bonding stability can be obtained by combining this rolled copper foil substrate with a PTFE layer.

[0019] Specifically, a polytetrafluoroethylene (PTFE) composite rolled copper foil includes a rolled copper foil substrate and a PTFE layer laminated on one side of the rolled copper foil substrate. The rolled copper foil substrate is obtained through the following process: continuous differential rolling is performed within a range of at least 40% cumulative reduction in the later stages of cold rolling, under a total cold rolling reduction rate of not less than 99%, combined with segmented annealing to suppress complete recrystallization, to obtain a fibrous elongated grain structure continuously distributed along the rolling direction; preferably, the rolled copper foil substrate satisfies a recrystallization volume fraction ≤15% and an AR ≥24. Based on the above structural characteristics, the PTFE layer, after being laminated with the rolled copper foil substrate, helps the resulting composite rolled copper foil maintain good interfacial bonding stability under repeated bending and thermal cycling conditions.

[0020] II. Composite of PTFE layer with rolled copper foil substrate: In existing technologies, the lamination of PTFE and copper foil typically focuses on improving interfacial adhesion through surface treatment, roughening treatment, or the application of an adhesive layer. This invention, in addition to addressing interfacial lamination conditions, also focuses on the influence of the microstructure characteristics of the rolled copper foil substrate on the stability of the composite structure.

[0021] Specifically, this invention first constructs a continuously distributed fibrous elongated grain structure along the rolling direction within the copper foil through high total reduction cold rolling, subsequent continuous differential speed rolling, and segmented annealing to suppress complete recrystallization; then, a PTFE layer is laminated onto the surface of the rolled copper foil substrate. This technical solution is beneficial for improving the interfacial bonding stability of the composite structure under bending, vibration, and thermal cycling conditions.

[0022] Compared with the prior art, the present invention forms a fibrous elongated grain structure that is continuously distributed along the rolling direction in the rolled copper foil substrate, and composites a PTFE layer on the surface of the rolled copper foil substrate. This is beneficial to improving the structural stability and interfacial bonding stability of the composite structure under repeated bending, vibration and thermal cycling conditions, and is especially suitable for composite copper foil applications in the thinner range. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating the manufacturing process and grain structure evolution of the polytetrafluoroethylene (PTFE) composite rolled copper foil of the present invention. As shown in the figure, the copper billet is sequentially subjected to multiple cold rolling passes, continuous differential rolling in the later stage of cold rolling, and segmented annealing treatment to suppress complete recrystallization. This forms a continuously fibrous grain structure along the rolling direction in the rolled copper foil. Based on this, it is then single-sidedly composited with polytetrafluoroethylene (PTFE) to obtain the polytetrafluoroethylene composite rolled copper foil.

[0024] Figure 2 This is a schematic diagram (planar view) of the equiaxed grain structure of a cast copper plate. As shown in the figure, the grains in the cast copper plate are distributed in an equiaxed manner, with random orientation of each grain and no obvious directionality at the grain boundaries.

[0025] Figure 3 This is a schematic diagram (planar, comparative example) of the elongated grain structure formed under conventional cold rolling conditions. As shown in the figure, under conventional cold rolling conditions dominated by plane strain, although the grains are elongated along the rolling direction, they are not discontinuous and interconnected, and there are a large number of transverse grain boundaries.

[0026] Figure 4 This is a schematic diagram (planar view) of the continuous fibrous grain structure formed under the conditions of this invention. As shown in the figure, under the conditions of continuous differential rolling in the later stage of cold rolling and segmented annealing to suppress complete recrystallization, the grains extend and distribute continuously along the rolling direction, the transverse grain boundaries decrease, and a continuous fibrous elongated grain structure is formed.

[0027] Figure 5 This is a schematic diagram (planar view) of the grain structure inhibiting complete recrystallization after segmented annealing. As shown in the figure, the segmented annealing causes the material to recover or partially recrystallize, while the grains still maintain a continuously elongated fibrous morphology along the rolling direction, which is beneficial for preserving the continuous fibrous grain structure.

[0028] Figure 6 This is a schematic cross-sectional view of the layered structure of the polytetrafluoroethylene (PTFE) composite rolled copper foil of the present invention. As shown in the figure, the PTFE composite rolled copper foil includes a rolled copper foil substrate with a continuous fibrous grain structure, and a polytetrafluoroethylene (PTFE) layer laminated on one side of the rolled copper foil substrate.

[0029] Figure 7 This is a schematic diagram comparing the crack propagation paths of the present invention and existing technologies under bending conditions. Wherein, Figure 7 This illustrates a situation in the prior art where cracks propagate rapidly along transverse grain boundaries under grain structure conditions, easily leading to interface delamination.

[0030] Figure 8 This invention illustrates a situation where cracks propagate along the grain interior or around grain boundaries in the continuous fibrous grain structure, significantly extending the propagation path and thereby improving the stability of the composite interface. Detailed Implementation

[0031] Determinable clauses: (1) Orientation and cross-section definition: The rolling direction is RD, the normal direction is ND, and the transverse direction is TD.

[0032] (2) Determination of grain aspect ratio AR: Prepare EBSD samples or metallographic samples in the RD–ND section; select no less than 5 fields of view, and count no less than 200 grains in each field of view; calculate the ratio of the length of the major axis in the RD direction to the length of the minor axis in the ND direction for each grain to obtain the grain aspect ratio; take the arithmetic mean of the aspect ratios of all grains as AR.

[0033] (3) Determination of rolling texture fraction F_tex: The orientation area fraction (or volume fraction) related to β-fiber is calculated using EBSD orientation data, and the fraction is used as F_tex.

[0034] (4) Estimation of dislocation density ρ: The dislocation density is estimated by using the EBSD-KAM method or the XRD linewidth method. When using the EBSD-KAM method, ρ is obtained based on the KAM statistical results according to the existing KAM-GND conversion relationship and expressed as m^-2.

[0035] (5) Determination of recrystallization volume fraction: The recrystallization volume fraction is determined by EBSD or metallographic statistical methods. When EBSD is used, grains are divided by high-angle grain boundaries, and recrystallized grains and deformed grains are distinguished based on the criterion of orientation difference / internal orientation gradient. The recrystallized grain area fraction (or volume fraction) is then used as the recrystallization volume fraction.

[0036] (6) Determination of 180° peel strength: The composite copper foil is made into samples of the same width, preferably 10 mm. The same 180° peel method and constant peel speed are used for testing. The average peel force during the peeling process is recorded and converted into peel strength per unit width. At least 5 samples are tested and the average value is taken. The embodiments and comparative examples in this paper are compared horizontally using the same sample preparation method and test conditions.

[0037] (7) Determination of flexural life: Cyclic bending is performed using the same bending radius, cycle frequency and failure criteria. The number of cycles when the interface lifts, peels off or the conductive layer fails is recorded as the flexural life. The bending radius is preferably 1 mm. The embodiments and comparative examples in this paper are compared horizontally using the same test conditions.

[0038] Example 1: Raw materials: oxygen-free copper ≥99.90 wt%; initial thickness: 3.2 mm; final thickness: 10 μm; total reduction rate: 99.69%.

[0039] Differential rolling: Located in the last 45% cumulative reduction range; Vs=1.24; percentage of differential rolling passes in the later stage: 75%.

[0040] Segmented annealing: Annealing 1: 380°C × 60 s (cumulative reduction of approximately 50%); Annealing 2: 370°C × 45 s (cumulative reduction of approximately 75%); Atmosphere: N2 / reducing; Recrystallization volume fraction: 8%; ΔHV: 25 HV.

[0041] Organization: AR=24.8; Ftex=74%; ρ=6×10^14 m^-2.

[0042] PTFE composite: Cu (10 μm) / PTFE (12 μm) single-sided composite; lamination: 340°C, 0.8 MPa, 90 s.

[0043] Performance examples: 180° peel strength not less than 1.2 N / mm; flexural life not less than 50,000 cycles; no obvious lifting or through-peeling is observed at the interface after bending.

[0044] Example 2 (Ultra-thin Reinforcement): Final thickness: 6 μm; Vs = 1.26; differential speed pass ratio ≥ 80%; recrystallization volume fraction ≤ 6%; AR = 27.5; Ftex = 78%; ρ = 8 × 10^14 m^-2. PTFE composite conditions can be set according to Example 1. The resulting composite rolled copper foil exhibits high 180° peel strength and a folding life of not less than 70,000 cycles.

[0045] Example 3 (thick foil version, satisfying AR≥24): Final thickness: 12 μm; total reduction rate approximately 99.63%; Vs=1.22; final 30%-50% coverage in the later stage; differential speed pass ratio in the later stage ≥70%; segmented annealing: 370-390°C × 40-70 s twice; recrystallization volume fraction ≤10%; AR≥24.0; Ftex≥68%; ρ=3×10^14-6×10^14 m^-2. PTFE composite conditions can be set according to Example 1. The resulting composite rolled copper foil exhibited good interfacial bonding stability under uniform testing conditions.

[0046] Comparative Example 1 (without differential shear dominance): Total reduction: 99.69%; Vs=1.00 (full-process symmetrical rolling); Annealing same as Example 1; Recrystallization volume fraction ≤15%; The resulting microstructure AR was lower than that of Example 1, the flexural life after composite was lower than that of Example 1, and it was more prone to interfacial strip-like peeling after bending.

[0047] Comparative Example 2 (differential speed exists but is discontinuous and does not constitute a dominant coverage in the later stage): Total reduction rate: 99.69%; Although there is a differential speed pass with Vs=1.25, the differential speed coverage in the later stage is insufficient and does not constitute a continuous dominant coverage; Annealing is the same as in Example 1; Recrystallization volume fraction ≤15%. The resulting microstructure lacks continuity, and compared with Example 1, the improvement in interfacial bonding stability after composite is not significant.

[0048] Comparative Example 3 (excessive annealing leading to significant recrystallization): Total reduction: 99.69%; Vs = 1.24; excessive annealing window (e.g., 420°C × 180 s or equivalent conditions); recrystallization volume fraction significantly increased (e.g., 45%). The resulting fibrous elongated grain structure was significantly weakened, AR was lower than in Example 1, and the flexural strength and interfacial bonding stability decreased after composite formation.

[0049] Comparison of process parameters (corrected for comparative example direction): Compared with comparative example 1 (Vs=1.00, symmetrical rolling), the present invention, by implementing continuous differential speed rolling in the later stage of cold rolling, is beneficial to forming a continuously distributed fibrous elongated grain structure along the RD direction, and is beneficial to improving the interfacial bonding stability and bending life after composite.

[0050] Compared to Comparative Example 2 (where differential rolling is discontinuous and not dominant in the later stage), the present invention uses a differential rolling path with continuous dominant coverage in the later stage, which is more conducive to forming a fibrous elongated grain structure with higher microstructure continuity.

[0051] Compared with Comparative Example 3 (where excessive annealing led to significant recrystallization), the present invention employs segmented annealing to suppress complete recrystallization, which is beneficial for preserving the formed fibrous elongated grain structure and for maintaining good interfacial bonding stability after composite formation.

[0052] The above parameters illustrate that: elongated grains continuously distributed along the rolling direction are beneficial to improving the load-bearing and constraint capacity of rolled copper foil substrate in composite structures; the microstructure characteristics, combined with the composite layer structure, are beneficial to reducing local stress concentration at the interface; under bending and thermal cycling conditions, they are beneficial to suppressing interface peeling and microcrack formation; therefore, they are suitable for applications such as high-speed cables that have high requirements for bending resistance and interface stability.

[0053] It should be noted that the above embodiments are used to illustrate the technical concept of the present invention, and are not intended to limit the scope of protection of the present invention; any equivalent substitutions or conventional adjustments made by those skilled in the art without departing from the core concept of the present invention should fall within the scope of protection of the present invention.

Claims

1. A polytetrafluoroethylene composite rolled copper foil, characterized in that: The invention includes a rolled copper foil substrate and a polytetrafluoroethylene (PTFE) layer laminated on at least one side of the rolled copper foil substrate. The rolled copper foil substrate is obtained by multiple cold rolling passes from a copper billet, with a total cold rolling reduction rate ≥99%. Continuous differential rolling is performed in the range where the cumulative reduction rate in the later stage of cold rolling is ≥40%, so that the ratio of the upper and lower work roll linear speeds Vs is 1.20-1.

30. Segmented annealing is performed under conditions that suppress complete recrystallization, so that the resulting rolled copper foil substrate has a fibrous elongated grain structure continuously distributed along the rolling direction, and the recrystallization volume fraction is ≤15% and the grain aspect ratio AR is ≥24.

2. The polytetrafluoroethylene composite rolled copper foil according to claim 1, characterized in that: The continuous fibrous grain structure is characterized by grains being oriented and elongated along the rolling direction, forming a grain band region that extends continuously along the rolling direction, and the number of transverse grain boundaries is reduced.

3. The polytetrafluoroethylene composite rolled copper foil according to claim 1 or 2, characterized in that: The aspect ratio AR of the rolled copper foil substrate is ≥24, preferably ≥27.

4. The polytetrafluoroethylene composite rolled copper foil according to any one of claims 1-3, characterized in that: The rolling texture fraction Ftex of the rolled copper foil substrate is ≥60%, preferably ≥65%.

5. The polytetrafluoroethylene composite rolled copper foil according to claim 4, characterized in that: The rolled texture includes one or more orientation components in β-fiber.

6. The polytetrafluoroethylene composite rolled copper foil according to any one of claims 1-5, characterized in that: The dislocation density ρ of the rolled copper foil substrate is 3×10^14-1×10^15 m^-2.

7. The polytetrafluoroethylene composite rolled copper foil according to any one of claims 1-6, characterized in that: The PTFE layer is bonded to the rolled copper foil substrate through an intermediate adhesive layer disposed between the PTFE layer and the rolled copper foil substrate.

8. The polytetrafluoroethylene composite rolled copper foil according to claim 7, characterized in that: The intermediate adhesive layer is a fluorinated thermoplastic polymer layer, preferably FEP, PFA or a combination thereof.

9. The polytetrafluoroethylene composite rolled copper foil according to claim 7 or 8, characterized in that: The thickness of the intermediate adhesive layer is 1-20 μm, preferably 3-12 μm.

10. The polytetrafluoroethylene composite rolled copper foil according to any one of claims 1-9, characterized in that: The rolled copper foil substrate has a controlled micro-roughened surface on the side that is laminated with the PTFE layer, so as to facilitate the lamination of the PTFE layer or intermediate adhesive layer with the rolled copper foil substrate.

11. The polytetrafluoroethylene composite rolled copper foil according to any one of claims 1-10, characterized in that: The total thickness of the polytetrafluoroethylene composite rolled copper foil is 8-60 μm, wherein the thickness of the rolled copper foil substrate is 6-35 μm.

12. The polytetrafluoroethylene composite rolled copper foil according to any one of claims 1-11, characterized in that: The PTFE layer is located on the side of the polytetrafluoroethylene composite rolled copper foil closest to the insulating medium.

13. The polytetrafluoroethylene composite rolled copper foil according to any one of claims 1-12, characterized in that: The polytetrafluoroethylene composite rolled copper foil is used as the electromagnetic shielding layer for high-speed cables.

14. A method for manufacturing polytetrafluoroethylene composite rolled copper foil, characterized in that... The process includes the following steps: a) providing a copper billet and performing surface cleaning treatment; b) performing multiple cold rolling passes on the copper billet until the target thickness is reached, wherein the total cold rolling reduction rate is ≥99%; c) performing continuous differential rolling in the range where the cumulative reduction rate in the latter part of the cold rolling is ≥40%, so that the ratio of the upper and lower work roll linear speeds Vs is 1.20-1.30; d) performing segmented annealing treatment to suppress complete recrystallization during the cold rolling process, so that the recrystallization volume fraction of the resulting rolled copper foil substrate is ≤15%, and a continuously distributed fibrous elongated grain structure is formed in the rolling direction with a grain aspect ratio AR ≥24; e) laminating a polytetrafluoroethylene (PTFE) layer onto one side of the rolled copper foil substrate to obtain a polytetrafluoroethylene composite rolled copper foil.

15. The method for manufacturing polytetrafluoroethylene composite rolled copper foil according to claim 14, characterized in that: The continuous differential rolling process covers ≥60% of the differential passes in the latter section, preferably ≥70%.

16. The method for manufacturing polytetrafluoroethylene composite rolled copper foil according to claim 14 or 15, characterized in that: The latter section refers to the last 30%-50% of the total cold rolling reduction.

17. The method for manufacturing polytetrafluoroethylene composite rolled copper foil according to any one of claims 14-16, characterized in that: The segmented annealing includes at least two short-duration annealing processes, one before entering the subsequent continuous differential rolling and the other during the subsequent continuous differential rolling process.

18. A method for manufacturing polytetrafluoroethylene composite rolled copper foil according to any one of claims 14-17, characterized in that: After the segmented annealing treatment, the Vickers hardness of the rolled copper foil substrate decreases by ΔHV by 10-35 HV.

19. The method for manufacturing polytetrafluoroethylene composite rolled copper foil according to any one of claims 14-18, characterized in that: The segmented annealing is performed under a protective atmosphere and / or a reducing atmosphere.

20. The method for manufacturing polytetrafluoroethylene composite rolled copper foil according to any one of claims 14-19, characterized in that: Before the composite PTFE layer, the rolled copper foil substrate is subjected to surface roughening and / or surface activation treatment.

21. The method for manufacturing polytetrafluoroethylene composite rolled copper foil according to any one of claims 14-20, characterized in that: The PTFE layer is laminated with the rolled copper foil substrate through an intermediate adhesive layer.

22. The method for manufacturing polytetrafluoroethylene composite rolled copper foil according to claim 21, characterized in that: The intermediate adhesive layer is a fluorinated thermoplastic polymer layer, preferably FEP, PFA or a combination thereof, and melts or softens during the composite process to form a laminated composite interface between the PTFE layer and the rolled copper foil substrate.

23. The method for manufacturing polytetrafluoroethylene composite rolled copper foil according to any one of claims 14-22, characterized in that: The lamination process is carried out under heating and pressurization conditions, which melts or softens the intermediate adhesive layer and forms a lamination interface between the PTFE layer and the rolled copper foil substrate.

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