224G and 448G cable with high-attachment low-warp composite copper foil and manufacturing method

Abstract

The application discloses a kind of 224G and 448G cable with high adhesion low warping composite copper foil and preparation method.The material includes first copper layer, PET base film layer and second copper layer stacked in turn, PET base film layer thickness is 8 μm-10 μm, both sides copper layer thickness is 1.8 μm-2.2 μm, and the thickness difference is not more than 0.3 μm.PET base film layer and both sides copper layer are provided with interface bonding area formed by surface activation, and copper layer includes copper seed layer and electroplated copper thickening layer.Through interface enhancement, double-sided synchronous electroplating, low tension heat stabilization and surface flattening treatment, the adhesion of the obtained material is not less than 100 gf / cm, the warping height of 100 mm sample is not more than 3 mm, Ra is 0.03 μm-0.3 μm, no crack, blister or peeling after 1 mm mandrel 180 ° bending, suitable for 224G, 448G high-speed communication cable and data center high-speed interconnection cable.

Description

Technical Field

[0001] This invention relates to the field of high-speed communication cable materials technology, specifically to a high-adhesion, low-warpage composite copper foil for 224G and 448G cables and its manufacturing method, and particularly to a composite copper foil coating material suitable for 224G high-speed communication cables, 448G high-speed communication cables, AI server high-speed interconnect cables, GPU high-speed interconnect cables, switch high-speed interconnect cables and data center high-speed interconnect cables. Background Technology

[0002] With the development of artificial intelligence servers, high-speed GPU interconnects, data center switching equipment, and high-speed communication systems, the data transmission rate of high-speed communication cables is constantly increasing. For high-speed communication cables such as 224G and 448G, the cable sheathing material not only needs to meet the requirements of shielding and conductivity, but also needs to maintain low conductor loss, low impedance fluctuation, good dimensional stability, and high bending reliability under high-frequency signal transmission conditions.

[0003] Previous publication CN108376580A disclosed a low-loss high-speed cable and a flat cable. The high-speed cable includes a core assembly, a first shielding layer, a second shielding layer, and an outer sheath. The first shielding layer can be a copper foil layer, and the second shielding layer can be an aluminum foil layer. This solution mainly improves the shielding effect from the overall structure of the high-speed cable and the configuration of the shielding layers, but it does not specifically design for the copper layer / PET interface adhesion, stress balance of the double-sided copper layers, low roughness, and low warpage performance of the copper foil sheathing material itself.

[0004] The previously published document WO2021134865A1 discloses a high-speed cable and its unit structure, which uses a combination of longitudinal shielding and wrapping shielding to improve shielding effect and structural compactness. Although this solution recognizes that the wrinkles in the shielding layer will affect transmission efficiency, its focus is still on the cable unit structure, and it does not solve the problem of balancing interface bonding, low surface roughness, low warpage, and bending reliability under thin-film conditions from the source of the shielding covering material.

[0005] Prior published documents CN114597418A and WO2024011536A1 relate to composite current collectors for batteries, which disclose the technical approach of forming a conductive transition layer or metal layer on the surface of a polymer base film. However, the above solutions are mainly aimed at lithium-ion battery current collectors, focusing on metal content, energy density, composite current collector thickness, or battery application performance, and do not address requirements for 224G and 448G high-speed communication cables regarding sheath warpage, wrapping / longitudinal wrapping reliability, high-frequency insertion loss, and impedance fluctuation control.

[0006] Therefore, there are still differences in application scenarios, evaluation indicators, and process constraints between existing high-speed cable shielding structures and composite copper foils used in batteries. For 224G and 448G high-speed communication cables, the shielding coating material needs to simultaneously meet the requirements of low warpage during the coating process, high adhesion of the copper layer / PET, low surface roughness, no peeling after bending, and low impedance fluctuation and low insertion loss in high-frequency signal transmission while maintaining an extremely thin thickness. However, existing technologies have not yet provided a solution for the coordinated control of material structure and process to address the aforementioned technical contradictions. Summary of the Invention

[0007] The purpose of this invention is to provide a high-adhesion, low-warpage composite copper foil for 224G and 448G cables and its manufacturing method. By limiting the PET base film thickness, double-sided copper layer thickness, interface bonding area, copper layer layer structure, double-sided copper layer thickness difference, low-tension thermal stability treatment conditions, and surface smoothing treatment results, the composite copper foil coating material can simultaneously meet the requirements of 224G and 448G high-speed communication cables for low loss, low warpage, high adhesion, bending reliability, and stable coating with measurable indicators.

[0008] The design mechanism of this invention is as follows: The PET base film layer serves as an intermediate flexible support layer, providing dimensional stability for the composite copper foil during slitting, winding, longitudinal wrapping, wrapping, and overlapping processes. Furthermore, it reduces the amount of copper used, making the material lighter, thinner, and more flexible compared to a full-layer copper foil. If the PET base film layer is too thin, it is prone to deformation or breakage during roll-to-roll processing and wrapping; if it is too thick, it affects cable miniaturization and flexible wrapping. Therefore, its thickness is limited to 8μm-10μm.

[0009] The first and second copper layers provide a continuous conductive path and electromagnetic shielding. Controlling the thickness of the copper layers on both sides between 1.8 μm and 2.2 μm achieves a balance between conductive shielding capability, coating flexibility, and interface reliability. If the copper layers are too thin, conductive continuity and shielding capability are insufficient; if the copper layers are too thick, material rigidity and interface stress increase, easily causing warping and peeling.

[0010] The interface bonding region is formed by plasma treatment, corona treatment, ion cleaning, ultraviolet ozone treatment, or chemical micro-roughening treatment. This can create polar group-rich areas, micro-roughened areas, or surface energy-enhancing areas on the PET surface, thereby strengthening the mechanical interlocking and interfacial bonding between the copper seed layer and the PET base film. Further addition of transition bonding layers such as Ti, Cr, Ni, NiCr alloy layers, CuOx, SiOx, AlOx, or organosilicon coupling layers can reduce the interfacial mismatch between the organic polymer layer and the metallic copper layer. Specifically, Ti, Cr, Ni, or NiCr alloy layers are suitable for formation via magnetron sputtering, vacuum evaporation, or ion plating to improve the bonding strength between the metallic copper layer and the activated areas on the PET surface; CuOx, SiOx, or AlOx layers are suitable for improving interfacial polarity and barrier stability; and organosilicon coupling layers are suitable for forming an organic-inorganic transition interface between the PET base film and the metal layer.

[0011] Double-sided synchronous electroplating is used to make the thickness and internal stress of the copper layers on both sides symmetrical, controlling the thickness difference between the first and second copper layers to no more than 0.3 μm. Low-tension thermal stabilization treatment is used to release residual processing stress under relatively low conveyor tension, reducing warping tendency during subsequent hot pressing, wrapping, longitudinal wrapping, and bending. Surface leveling treatment is used to control the outer surface roughness Ra of the copper layer to 0.03 μm-0.3 μm, thereby reducing conductor loss and impedance fluctuation in high-frequency signal transmission. The above-mentioned interface bonding, stress balance, thermal stabilization, and leveling treatments work together to ensure that the material does not rely on a single layered structure to achieve its effect, but rather achieves comprehensive performance through the coordinated control of material structural parameters and roll-to-roll process parameters.

[0012] The technical solution of this invention is as follows: a high-adhesion, low-warpage composite copper foil covering material for high-speed communication cables. The composite copper foil covering material is a strip-shaped composite material used for shielding and covering high-speed communication cables, comprising a first copper layer, a PET base film layer, and a second copper layer stacked sequentially. The PET base film layer has a thickness of 8 μm-10 μm. The first and second copper layers are respectively disposed on two opposite surfaces of the PET base film layer, with thicknesses of 1.8 μm-2.2 μm respectively. A first interface bonding region is provided between the PET base film layer and the first copper layer, and a second interface bonding region is provided between the PET base film layer and the second copper layer. The interface bonding area is a surface-activated region formed on the surface of the PET base film layer after activation treatment; both the first copper layer and the second copper layer include a copper seed layer and an electroplated copper thickening layer; the thickness difference between the first copper layer and the second copper layer is not greater than 0.3 μm; the average adhesion between the first copper layer and the PET base film layer and between the second copper layer and the PET base film layer is not less than 100 gf / cm, the warpage height of a 100 mm long sample is not greater than 3 mm, the surface roughness Ra of the copper layer is 0.03 μm-0.3 μm, and the sheet resistance of the first copper layer and the second copper layer is not greater than 0.05 Ω / □.

[0013] The preparation method of this invention includes: cleaning treatment of PET base film, double-sided surface activation, formation of copper seed layer, double-sided synchronous electroplating of copper for thickness enhancement, low-tension thermal stabilization treatment, surface smoothing treatment, and winding. The low-tension thermal stabilization treatment is carried out at 60℃-130℃, 10min-180min, and 5N / m-80N / m. The surface smoothing treatment achieves an outer surface roughness Ra of 0.03μm-0.3μm for both the first and second copper layers. Double-sided synchronous electroplating makes the thickness and internal stress of the copper layers on both sides tend to be symmetrical. The low-tension thermal stabilization treatment releases the residual stress accumulated in the PET base film and copper layers during pretreatment, electroplating, and drying. The surface smoothing treatment reduces the outer surface roughness of the copper layers.

[0014] Compared with existing technologies, this invention does not merely provide a general Cu / PET / Cu layered structure. Instead, in the application scenario of high-speed communication cable sheathing materials, it defines an overall technical solution that includes an 8μm-10μm PET base film, a 1.8μm-2.2μm double-sided copper layer, a copper layer thickness difference of no more than 0.3μm on both sides, high adhesion of the copper layer / PET, low warpage of 100mm samples, and a low-roughness outer surface. Through the combination of "interface bonding enhancement, layered construction of copper seed layer and electroplated copper thickening layer, stress balance of double-sided synchronous electroplating, low-tension thermal stability, and surface smoothing", the composite copper foil sheathing material simultaneously possesses high adhesion, low warpage, low roughness, good bending reliability, and relatively stable high-speed signal transmission performance.

[0015] Testing methods and evaluation standards

[0016] 1. Average adhesion: The composite copper foil coating material was cut into samples with a width of 10 mm. The first copper layer and the second copper layer were peeled off from the PET base film layer respectively. The peeling force between the first copper layer and the PET base film layer and between the second copper layer and the PET base film layer were measured using a 180° peeling method. The peeling speed was 50 mm / min. At least 5 points were tested on each surface, and the average value was taken as the average adhesion force between the corresponding copper layer and the PET base film layer.

[0017] 2. Warpage height: Cut the composite copper foil covering material into samples with a length of 100mm and a width of 10mm. After placing the samples in an environment of 23℃ and 50% relative humidity for 24 hours, place the samples freely on a horizontal glass plate and measure the vertical distance between the highest point of the sample and the surface of the glass plate as the warpage height.

[0018] 3. Surface roughness Ra: The arithmetic mean roughness Ra of the outer surfaces of the first and second copper layers is measured using a contact surface roughness meter, white light interferometer or laser confocal microscope, respectively. At least 5 measurement points are used for each surface, and the average value is taken.

[0019] 4. Sheet resistance of surfaces: The sheet resistance of the outer surfaces of the first and second copper layers is measured using the four-probe method. At least 5 measurement points are used on each surface, and the average value is taken.

[0020] 5. 180° bending test: The composite copper foil covering material is bent 180° around a cylindrical mandrel with a radius of 1mm. After bending, the first copper layer and the second copper layer are observed at a magnification of not less than 20 times to see if cracks, bubbles or peeling occur.

[0021] 6. Adhesion retention rate after heat treatment: After heat treatment of the composite copper foil coating material at 120℃ for 30 minutes, the average adhesion of the first copper layer and the second copper layer after heat treatment is measured according to the average adhesion test method described above. The adhesion retention rate of the corresponding copper layer is calculated according to "average adhesion after heat treatment / average adhesion before heat treatment × 100%".

[0022] 7. Thermal shrinkage rate: The composite copper foil covering material was cut into 100mm samples along the longitudinal and transverse directions, treated at 120℃ for 30min, cooled to room temperature and the dimensional change was measured, and the thermal shrinkage rate was calculated according to the length change rate before and after treatment.

[0023] 8. High-speed communication cable performance: A 1m high-speed communication cable prototype was fabricated using composite copper foil as the shielding layer. Insertion loss was tested at a 40GHz test frequency using a vector network analyzer, and impedance fluctuation was measured using impedance testing equipment. Impedance fluctuation is defined as the maximum positive and maximum negative deviation relative to the nominal impedance of the prototype, used to evaluate the material's impact on the stability of high-speed signal transmission. The 40GHz test frequency is used to evaluate the relative insertion loss and impedance stability of the material under high-frequency transmission conditions and does not constitute a limitation on the actual transmission rate or sole operating frequency of the high-speed communication cable. Depending on the cable standard and application scenario, further extended evaluations can be conducted at frequencies such as 56GHz, 67GHz, or 80GHz. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the layered structure of the high-adhesion, low-warpage composite copper foil covering material for high-speed communication cables of the present invention.

[0025] Figure 2 This is a schematic diagram of the layered structure of the composite copper foil coating material containing a transition bonding layer according to the present invention.

[0026] Figure 3 This is a schematic flowchart of the method for preparing the composite copper foil coating material of the present invention.

[0027] Figure 4 This is a schematic diagram of the structure of the composite copper foil covering material of the present invention covering the outside of a high-speed communication cable.

[0028] Explanation of reference numerals in the attached drawings: 1. First copper layer; 11. First copper seed layer; 12. First electroplated copper thickening layer; 2. PET base film layer; 21. First interface bonding area; 22. Second interface bonding area; 23. First transition bonding layer; 24. Second transition bonding layer; 3. Second copper layer; 31. Second copper seed layer; 32. Second electroplated copper thickening layer; 4. Composite copper foil covering material; 5. Conductor core wire; 6. Insulation layer; 7. Shielding covering layer; 8. Sheath layer.

[0029] Example 1: Refer to Figure 1 This embodiment provides a Cu2 / PET8 / Cu2 composite copper foil coating material 4. The material comprises a first copper layer 1, a PET base film layer 2, and a second copper layer 3, stacked sequentially. The PET base film layer 2 has a thickness of 8 μm, and the first copper layer 1 and the second copper layer 3 each have a thickness of 2 μm. A first interface bonding region 21 is provided between the PET base film layer 2 and the first copper layer 1, and a second interface bonding region 22 is provided between the PET base film layer 2 and the second copper layer 3. Both interface bonding regions are surface-activated regions formed after plasma treatment of the PET base film layer. The first copper layer 1 includes a first copper seed layer 11 and a first electroplated copper thickening layer 12, and the second copper layer 3 includes a second copper seed layer 31 and a second electroplated copper thickening layer 32. The thickness of the copper seed layer is 100 nm-300 nm. The thickness difference between the first copper layer 1 and the second copper layer 3 is no greater than 0.3 μm; the average adhesion between the first copper layer 1 and the PET base film layer 2, and between the second copper layer 3 and the PET base film layer 2, is no less than 100 gf / cm.

[0030] Example 2: This example is basically the same as Example 1, except that the thickness of the PET base film layer 2 is 10 μm, and the thicknesses of the first copper layer 1 and the second copper layer 3 are 2 μm, forming a Cu2 / PET10 / Cu2 layered structure. The 10 μm PET base film layer provides higher mechanical support, enabling the composite copper foil coating material to have better dimensional stability during slitting, winding, longitudinal wrapping, wrapping, and overlapping.

[0031] Example 3: Reference Figure 2This embodiment is basically the same as Embodiment 1, except that: a first transition bonding layer 23 is provided between the first interface bonding region 21 and the first copper seed layer 11, and a second transition bonding layer 24 is provided between the second interface bonding region 22 and the second copper seed layer 31. The first transition bonding layer 23 and the second transition bonding layer 24 are one or more of Ti layer, Cr layer, Ni layer, NiCr alloy layer, CuOx layer, SiOx layer, AlOx layer or organosilicon coupling layer, with a thickness of 2nm-100nm. Among them, Ti layer, Cr layer, Ni layer or NiCr alloy layer can be formed by magnetron sputtering, vacuum evaporation or ion plating; CuOx layer, SiOx layer or AlOx layer can be formed by reactive sputtering, oxidation treatment or sol-gel method; organosilicon coupling layer can be formed by coating, impregnation or roll coating.

[0032] Example 4: Reference Figure 3 This embodiment provides a method for preparing a composite copper foil coating material: S1, providing a PET base film with a thickness of 8μm-10μm, and performing unwinding, dust removal, oil removal, and drying treatments on the PET base film; S2, performing plasma treatment, corona treatment, ion cleaning, ultraviolet ozone treatment, or chemical micro-roughening treatment on the two opposite surfaces of the PET base film to form a first interface bonding region 21 and a second interface bonding region 22; S3, forming copper seed layers on the two interface bonding regions respectively; S4, using the copper seed layers as a conductive base, winding the PET base film on both sides... The copper foil is simultaneously electroplated on both sides to thicken it, so that the thickness of the copper layer on both sides reaches 1.8μm-2.2μm respectively, and the thickness difference is no more than 0.3μm; S5, the electroplated composite copper foil is washed and dried, and then subjected to low-tension heat stabilization treatment at 60℃-130℃, 10min-180min, and 5N / m-80N / m; S6, the composite copper foil after low-tension heat stabilization treatment is surface smoothed so that the surface roughness Ra of the first copper layer and the second copper layer both reach 0.03μm-0.3μm before being wound up.

[0033] Example 5: Refer to Figure 4 This embodiment provides a high-speed communication cable, including at least one conductor core 5, an insulation layer 6, a shielding layer 7, and a sheath layer 8. The insulation layer 6 covers the outside of the conductor core 5, the shielding layer 7 covers the outside of the insulation layer 6, and the sheath layer 8 is located outside the shielding layer 7. The shielding layer 7 includes the composite copper foil covering material 4 described in any one of Embodiments 1 to 3, and can be disposed outside the insulation layer 6 by longitudinal wrapping, wrapping, spiral wrapping, or overlapping wrapping.

[0034] Experimental examples and comparative examples To further illustrate the technical effects of the present invention, samples were prepared according to the following experimental examples and comparative examples, and their adhesion, warpage height, surface roughness, bending reliability, sheet resistance, impedance fluctuation and insertion loss were tested. Table 1. Structure and process conditions of experimental examples and comparative examples

[0035] Table 2 Test Results

[0036] Analysis of Experimental Results

[0037] As shown in Table 2, after using the PET base film thickness, double-sided copper layer thickness, interface bonding area, copper seed layer, electroplated copper thickening layer, double-sided synchronous electroplating, low-tension thermal stabilization treatment and surface smoothing treatment described in this invention, the average adhesion between the copper layers on both sides and the PET base film in Experimental Examples 1 and 2 reached 126 gf / cm and 118 gf / cm respectively, which is significantly higher than that of Comparative Example 1 without interface activation treatment.

[0038] The warpage heights of the 100mm samples in Experiment 1 and Experiment 2 were 2.1mm and 1.8mm, respectively, which were significantly lower than those in Comparative Example 2, which did not undergo double-sided simultaneous electroplating and low-tension thermal stabilization treatment. This indicates that controlling the thickness difference of the copper layers on both sides and low-tension thermal stabilization treatment have a significant effect on reducing the warpage of the composite material.

[0039] The surface roughness Ra of the copper layer in Experimental Examples 1 and 2 were 0.18 μm and 0.20 μm, respectively, lower than those in the comparative examples, indicating that surface smoothing treatment can effectively reduce the surface roughness of the copper layer. After fabricating a 1m long high-speed communication cable prototype from the obtained composite copper foil coating material, the impedance fluctuations in Experimental Examples 1 and 2 were ±1.8Ω and ±1.6Ω, respectively, and the insertion losses @40GHz were 4.8dB / m and 4.6dB / m, respectively, both superior to the comparative examples. This 40GHz test data illustrates the improved high-frequency transmission stability of the material compared to the comparative examples. When practically applied to 224G or 448G high-speed communication cables, further extended testing at higher frequencies can be conducted according to the corresponding cable standards and system requirements.

[0040] The above results indicate that the present invention does not achieve its technical effects solely through the Cu / PET / Cu layered structure. Rather, it achieves these effects through the synergistic effects of enhanced interfacial bonding, control of the thickness difference between the two copper layers, low-tension thermal stabilization treatment, and surface smoothing treatment. This allows the composite copper foil coating material to simultaneously possess high adhesion, low warpage, low surface roughness, good bending reliability, and stable high-speed signal transmission performance, making it more suitable for the coating, shielding, and conductive connection of 224G high-speed communication cables, 448G high-speed communication cables, and high-speed interconnect cables for data centers.

[0041] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. For those skilled in the art, any equivalent substitutions, combinations, or improvements made to the PET base film thickness, copper layer thickness, surface activation method, transition bonding layer material, copper seed layer formation method, electroplating method, surface leveling method, cable wrapping method, and application scenario without departing from the concept of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A high-adhesion, low-warpage composite copper foil for 224G and 448G cables, characterized in that: The composite copper foil covering material is a strip-shaped composite material used for shielding and covering high-speed communication cables, comprising a first copper layer, a PET base film layer, and a second copper layer stacked sequentially; the thickness of the PET base film layer is 8μm-10μm; the first copper layer and the second copper layer are respectively disposed on two opposite surfaces of the PET base film layer, and the thicknesses of the first copper layer and the second copper layer are 1.8μm-2.2μm, respectively; a first interface bonding region is provided between the PET base film layer and the first copper layer, and a second interface bonding region is provided between the PET base film layer and the second copper layer, wherein the first interface bonding region and the second interface bonding region are PET The surface activation region is formed on the surface of the base film layer after activation treatment; both the first copper layer and the second copper layer include a copper seed layer formed on the corresponding interface bonding area and an electroplated copper thickening layer formed on the outside of the copper seed layer; the thickness difference between the first copper layer and the second copper layer is not greater than 0.3 μm; the average adhesion between the first copper layer and the PET base film layer and between the second copper layer and the PET base film layer is not less than 100 gf / cm, and the warpage height of the composite copper foil covering material on a 100 mm long sample is not greater than 3 mm; the outer surface roughness Ra of the first copper layer and the second copper layer is 0.03 μm-0.3 μm.

2. The high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 1, characterized in that: The PET base film layer has a thickness of 8 μm, and the first copper layer and the second copper layer have thicknesses of 2 μm, forming a Cu2 / PET8 / Cu2 layered structure.

3. The high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 1, characterized in that: The PET base film layer has a thickness of 10 μm, and the first copper layer and the second copper layer have thicknesses of 2 μm, forming a Cu2 / PET10 / Cu2 layered structure.

4. The high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 1, characterized in that: The activation treatment is one or more of plasma treatment, corona treatment, ion cleaning, ultraviolet ozone treatment or chemical micro-roughening treatment, and the surface activation region is a polar group enrichment region, a micro-roughening region or a surface energy enhancement region.

5. The high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 1, characterized in that: A transition bonding layer is provided between the first interface bonding region and the first copper seed layer, and between the second interface bonding region and the second copper seed layer. The transition bonding layer is one or more of the following: Ti layer, Cr layer, Ni layer, NiCr alloy layer, CuOx layer, SiOx layer, AlOx layer, and organosilicon coupling layer.

6. The high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 5, characterized in that: The thickness of the transition bonding layer is 2nm-100nm.

7. The high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 1, characterized in that: The thickness of the copper seed layer is 30nm-300nm, and the thickness of the electroplated copper thickening layer is set to make the total thickness of the corresponding copper layer reach 1.8μm-2.2μm.

8. The high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 1, characterized in that: The sheet resistance of the outer surfaces of both the first and second copper layers is no greater than 0.05 Ω / □.

9. The high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 1, characterized in that: After the composite copper foil coating material was subjected to a 180° bending test on a cylindrical mandrel with a radius of 1 mm, it was observed at a magnification of no less than 20 times that neither the first copper layer nor the second copper layer showed any cracks, blistering, or peeling.

10. The high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 1, characterized in that: After the composite copper foil coating material is treated at 120°C for 30 minutes, the average adhesion retention rate between the first copper layer and the PET base film layer and between the second copper layer and the PET base film layer is not less than 85%.

11. The high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 1, characterized in that: The longitudinal and transverse thermal shrinkage rates of the composite copper foil coating material after treatment at 120°C for 30 minutes are both no greater than 1.0%.

12. The high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 1, characterized in that: The total thickness of the composite copper foil covering material is 11.6 μm-14.4 μm.

13. The high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 1, characterized in that: The composite copper foil covering material is a strip material with a width of 7.6mm-8.2mm.

14. A method for preparing a high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to any one of claims 1 to 13, characterized in that: The process includes the following steps: S1, providing a PET base film with a thickness of 8μm-10μm, and subjecting the PET base film to unwinding, dust removal, oil removal, and drying; S2, performing surface activation treatment on two opposing surfaces of the PET base film to form a first interface bonding region and a second interface bonding region on the two opposing surfaces of the PET base film, respectively; S3, forming copper seed layers on the first interface bonding region and the second interface bonding region, respectively; S4, using the copper seed layer as a conductive base, performing double-sided synchronous copper electroplating to thicken both sides of the PET base film, so that the PET base film... The thickness of the copper layers on both sides of the film reaches 1.8μm-2.2μm respectively, and the thickness difference between the two sides of the copper layers is no more than 0.3μm; S5, the electroplated composite copper foil is washed and dried, and subjected to low-tension thermal stabilization treatment under the conditions of 60℃-130℃, 10min-180min, and 5N / m-80N / m; S6, the composite copper foil after low-tension thermal stabilization treatment is subjected to surface smoothing treatment, so that the outer surface roughness Ra of the first copper layer and the second copper layer both reach 0.03μm-0.3μm, and then it is wound up to obtain the composite copper foil coating material.

15. The method for preparing high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 14, characterized in that: After step S2 and before step S3, the process further includes forming transition bonding layers on the first interface bonding region and the second interface bonding region, respectively. The transition bonding layer is one or more of the following: Ti layer, Cr layer, Ni layer, NiCr alloy layer, CuOx layer, SiOx layer, AlOx layer, and organosilicon coupling layer.

16. The method for preparing high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 14, characterized in that: In step S3, the copper seed layer is formed by magnetron sputtering, vacuum evaporation, ion plating, or chemical plating.

17. The method for preparing high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 14, characterized in that: In step S4, the double-sided synchronous electroplating adopts constant current electroplating, pulse electroplating or segmented current density electroplating. By controlling the current density on both sides, electroplating time, electrolyte flow rate and belt tension, the thickness difference between the first copper layer and the second copper layer is not greater than 0.3 μm and the internal stress difference between the two copper layers is reduced.

18. The method for preparing high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 14, characterized in that: The low-tension thermal stabilization treatment in step S5 is carried out by a continuous conveyor belt method. The treatment tension is applied uniformly along the width of the material, and the warpage height of the 100mm long sample after treatment is no more than 3mm.

19. The method for preparing high-adhesion, low-warpage composite copper foil for 224G and 448G cables according to claim 14, characterized in that: The surface leveling process in step S6 includes one or more of rolling leveling, low-pressure rolling, and tension leveling. During the surface leveling process, the rolling pressure or belt tension is controlled to reduce the roughness of the outer surface of the copper layer and prevent the copper layer from cracking or peeling.

20. A high-speed communication cable, characterized in that: It includes at least one conductor core wire, an insulating layer covering the outside of the conductor core wire, and a shielding covering layer covering the outside of the insulating layer, wherein the shielding covering layer includes the composite copper foil covering material according to any one of claims 1 to 13.

21. The high-speed communication cable according to claim 20, characterized in that: The composite copper foil covering material is applied to the outside of the insulation layer by means of longitudinal wrapping, wrapping, spiral wrapping, or overlapping wrapping.

22. The high-speed communication cable according to claim 20, characterized in that: The high-speed communication cable is a 224G high-speed communication cable, a 448G high-speed communication cable, an AI server high-speed interconnect cable, a GPU high-speed interconnect cable, a switch high-speed interconnect cable, or a data center high-speed interconnect cable.

23. The high-speed communication cable according to claim 20, characterized in that: When the composite copper foil covering material is used as a shielding covering layer to make a high-speed communication cable prototype with a length of 1m, the insertion loss of the high-speed communication cable prototype at a test frequency of 40GHz is no greater than 5.0dB / m, and the impedance fluctuation measured with the nominal impedance as a reference is no greater than ±2.0Ω.

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