A process for improving the interfacial bonding strength of polymer / metal films and its application.

Abstract

This invention relates to the field of materials manufacturing technology, specifically to a process method for improving the interfacial bonding strength of polymer / metal films and its application. The process method includes the following steps: 1) surface cleaning of a composite material of polyimide, polyetheretherketone, or cyanate; 2) Cu ion implantation into the composite material obtained in step 1) using plasma technology; 3) Cu metal layer deposition on the composite material obtained in step 2) using magnetically filtered arc ion plating or magnetron sputtering technology; 4) thermal diffusion treatment of the composite material obtained in step 3). This technical solution, through a continuously and gradually changing gradient transition layer, effectively mitigates the risk of interfacial failure caused by the mismatch in thermal expansion coefficients between heterogeneous materials, significantly improves the environmental stability and long-term reliability of the interface under complex service conditions such as thermal cycling and humid environments, and greatly expands the application scope of cyanate composite substrate metallized structures in high-frequency electronics, aerospace, and other fields.

Description

Technical Field

[0001] This invention relates to the field of materials manufacturing technology, specifically to a process method for improving the interfacial bonding strength of polymer / metal films and its application. Background Technology

[0002] The rapid development of high-frequency communication technology and high-performance airborne equipment in the aerospace field has placed increasingly stringent demands on composite materials that combine excellent structural load-bearing capacity, stable dielectric properties, and multifunctional integration characteristics. Cyanate ester resin-based composite materials, with their excellent high heat resistance, low water absorption, high specific strength, and stable high dielectric properties over a wide frequency range, combined with outstanding structural load-bearing capacity and high-frequency transmission characteristics, are ideal substrates for fabricating high-transmittance, high-weather-resistant, structurally integrated composite parts. They have been widely used in key core components such as airborne radomes and fuselage structural parts in the aerospace field. To meet the specific functional application requirements of fuselage lightning protection, overall electromagnetic shielding, and signal transmission grounding in the complex service environment of aerospace, surface metallization modification of cyanate ester composite materials is necessary. This modification method can impart good electrical conductivity, thermal conductivity, and electromagnetic control characteristics to the substrate surface while fully preserving the high chemical stability, excellent mechanical properties, and dielectric properties of the substrate itself, effectively expanding the application scenarios and functional boundaries of cyanate ester composite materials. Copper metal, with its excellent electrical and thermal conductivity, ease of processing, and significant low cost, has become the preferred core material for surface metallization modification of polymer substrates, and has received widespread attention and application in the surface metallization process of cyanate ester composite materials.

[0003] However, like high-performance polymer substrates such as polyimide and polyetheretherketone, cyanate ester composites exhibit strong chemical inertness and hydrophobicity on their surface. Their molecular chain structure lacks active polar groups that can form stable chemical bonds with metal atoms. At the same time, there are significant differences in the physicochemical properties of the substrate and metallic copper, such as the coefficient of thermal expansion and elastic modulus. This results in generally weak interfacial bonding when the two are directly bonded. Under harsh long-term service environments such as high and low temperature cycling and humid heat alternation in aerospace, they are prone to failure problems such as interfacial delamination and metal film peeling. This seriously restricts the service performance and service life of metallized cyanate ester composite devices, becoming a core technical bottleneck that limits their large-scale application in high-end aerospace functional devices.

[0004] To address the industry challenge of insufficient interfacial bonding strength between cyanate ester composite materials and copper films, existing technologies mainly focus on two directions: substrate surface activation modification and interfacial structure engineering. Mainstream techniques include plasma activation treatment, chemical roughening modification, and preparation of metal transition layers.

[0005] Plasma activation and chemical roughening enhance mechanical interlocking and chemical adsorption by introducing micro-roughness and polar groups onto the surface. However, the modified layer is usually limited to the shallowest nanoscale, resulting in short-lived modification effects. Furthermore, chemical roughening involves toxic and hazardous reagents, failing to meet environmental protection requirements. Transition layer deposition involves preparing metals such as Cr and Ti as adhesion layers between the polymer and Cu to improve interfacial stability, but this increases process steps and reduces the conductivity of the metal layer. In summary, existing modification technologies cannot simultaneously meet the stringent application requirements of advanced aerospace devices for high bonding strength, high conductivity, high environmental reliability, and low pollution at the metallized interface. Therefore, there is an urgent need to develop a novel modification technology that can fundamentally improve the interfacial bonding performance between cyanate ester composite materials and copper films.

[0006] Addressing the numerous shortcomings of existing technologies, this invention focuses on the problems of strong chemical inertness of cyanate ester composite materials, the difficulty of effectively improving the bonding strength between the composite material and the metal layer using traditional surface modification methods, and the inability to fundamentally improve the long-term service reliability of the interface. By implanting high-energy metal ions into the surface of the cyanate ester composite material, nanoscale anchor points and internal diffusion sources are formed, providing stable bonding sites for subsequent copper film deposition. After coating, low-temperature heat treatment promotes the controlled penetration of implanted metal ions and copper film atoms at the interface along polymer molecular chains or defect channels, forming a gradient transition layer with continuously changing composition and chemical state. Ultimately, this fundamentally improves the bonding strength and service reliability of the cyanate ester composite material and copper film interface, providing solid technical support for the large-scale application of metallized cyanate ester composite materials in high-end aerospace functional devices.

[0007] Furthermore, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the inventors studied a large number of documents and patents when making this invention, but due to space limitations, not all details and contents were listed in detail. However, this does not mean that the present invention does not possess the features of these prior art. On the contrary, the present invention already possesses all the features of the prior art, and the applicant reserves the right to add relevant prior art to the background art. Summary of the Invention

[0008] This invention relates to the field of materials manufacturing technology, specifically to a process method for improving the interfacial bonding strength of polymer / metal films and its application.

[0009] One objective of this invention is to provide a process method for improving the interfacial bonding strength of polymer / metal films, comprising the following steps: 1) Clean the surface of composites made of polyimide, polyetheretherketone, or cyanate ester; 2) Cu ion implantation is performed on the composite material obtained in step 1) using plasma technology, wherein the implantation energy is 10-25 keV, the implantation time is 5-20 min, and the implantation dose is controlled at 1×10⁻⁶. 17-5×10 17 ions / cm 2 Magnitude; 3) A Cu metal layer is deposited on the composite material obtained in step 2) using magnetic filtering arc ion plating or magnetron sputtering. The target material is a Cu metal target with a purity of 99.99%. Ar is introduced as the working gas, the deposition gas pressure is between 0.1 and 0.5 Pa, the arc current is between 50 and 70 A, a bias voltage of -50 to -100 V is applied during the deposition process, the deposition time is 2 to 3 h, and the film thickness is between 0.8 and 3.0 μm. 4) Perform thermal diffusion treatment on the composite material from step 3), with a baking temperature of 70-100 ℃ and a baking time of 4-10 h.

[0010] According to a preferred embodiment, surface cleaning includes wiping with anhydrous ethanol. The step of wiping with anhydrous ethanol includes: thoroughly rinsing the cyanate composite material with a lint-free cloth soaked in anhydrous ethanol to remove surface dust, and then drying it with clean air for later use.

[0011] According to a preferred embodiment, surface cleaning includes vacuum cleaning. The vacuum cleaning step includes: placing the composite material, or the composite material wiped with anhydrous ethanol, in a vacuum chamber and heating and baking it at 60 °C for 1-3 h to remove impurity gases adsorbed in the vacuum chamber and on the surface of the composite material, and then evacuating the vacuum to 1.0 × 10⁻⁶. -3 Below Pa.

[0012] According to a preferred embodiment, surface cleaning includes activation cleaning. The activation cleaning step includes: treating the composite material or the composite material wiped with anhydrous ethanol using plasma technology for 20 minutes to remove surface impurities and etch the surface. The cleaning source is selected from one of a Hall source ion source, an anodic layer ion source, or a Kaufman ion source.

[0013] According to a preferred embodiment, after the metal film deposition is completed in step 3), the vacuum chamber is vented and the furnace is opened to remove the processed composite material.

[0014] According to a preferred embodiment, the metal film is a Cu metal film.

[0015] According to a preferred embodiment, the heat diffusion treatment uses an oven with exhaust function to exhaust the impurity gases generated during baking while heating and baking.

[0016] One of the objectives of this invention is to provide a substrate obtained based on the above-described process for improving the bonding strength of the polymer / metal film interface.

[0017] According to a preferred embodiment, the bonding force between the composite material and the metal film in the substrate is not less than 4.50 MPa.

[0018] According to a preferred embodiment, the thickness of the metal film in the substrate is 0.8-3.0 μm. Preferably, the thickness of the metal film in the substrate is 0.8 μm, 1.2 μm, or 3.0 μm.

[0019] One of the objectives of this invention is to provide the use of substrates prepared by the above-described process for improving the bonding strength of polymer / metal film interfaces in the aerospace field.

[0020] One of the objectives of this invention is to provide the application of the above-described process for improving the interfacial bonding strength of polymer / metal films in the aerospace field.

[0021] Specifically, the substrate is used in the fabrication of lightning protection structural components for aircraft fuselages, electromagnetic shielding functional components for the entire aircraft, airborne high-frequency transparent antenna radomes, avionics equipment bearing housings, airborne high-speed signal transmission substrates, and integrated composite workpieces for aerospace structures and functions.

[0022] The beneficial effects of this technical solution are: The technical solution of this invention constructs a gradient transition layer with continuously changing composition and chemical state between the cyanate ester composite material and the Cu metal film through the synergistic control of three processes: metal ion implantation, plasma coating and low-temperature heat treatment. Unlike the traditional interface modification method that only relies on surface roughening or superimposed intermediate layers, this invention forms a strong bonding interface in situ from the inside of the substrate, fundamentally eliminating the defects of weak physical bonding, interface stress concentration and easy delamination failure in traditional heterogeneous interfaces, and significantly improving the interfacial bonding strength between the cyanate ester composite material and the Cu metal film.

[0023] It is important to emphasize that the interface strengthening process of this invention can only achieve a breakthrough in bonding strength improvement for the interface system between specific special polymer substrates and copper metal films. Compared to conventional polymers and metal materials, high-performance special polymer materials such as cyanate esters and liquid crystal polymers (LCPs) have more complex molecular chain cross-linking structures and surface chemical properties. There are fundamental differences in the types and quantities of surface functional groups, microscopic aggregation morphology, molecular chain gaps, and temperature resistance between different substrates, directly determining significant differences in their chemical bonding ability with copper metal films, metal atom diffusion behavior, and the final interface bonding effect. The process of this invention, through the synergistic regulation of ion implantation, plasma coating, and low-temperature thermal diffusion, can form a stable, continuously gradient transition layer of composition and chemical state at the interface between cyanate ester composites and copper metal films, achieving high interface peel strength. Under the same process parameters, this process cannot form the same stable gradient diffusion structure on other conventional polymer substrates, nor can it achieve the same level of interface bonding strength, fully demonstrating that the interface strengthening effect of this invention is highly dependent on the compatibility of the interface system between the specific cyanate ester substrate and the copper metal film.

[0024] The details are as follows: (1) By implanting high-energy copper ions onto the surface of cyanate ester to form nanoscale anchors and internal diffusion sources, and then driving the implanted copper ions and thin film copper atoms to diffuse into the composite material through low-temperature heat treatment, a gradient transition layer with continuously changing composition and chemical state is formed. Finally, the bonding strength between Cu film and cyanate ester substrate is improved from both physical interlocking and chemical bonding levels, and the bonding strength is significantly higher than that of traditional methods.

[0025] (2) Deposition at low temperature (≤150 ℃) and low pressure (0.1-0.5 Pa) allows copper atoms to diffuse fully during the growth process, resulting in a Cu film with high purity, high density, low grain boundary defects, and electrical properties close to those of bulk materials. At the same time, low-temperature deposition avoids damage to the cyanate ester substrate caused by high temperature.

[0026] (3) The highest temperature of the entire metallization process chain does not exceed 150 ℃, which is lower than the heat resistance temperature of most high-performance polymers. It can be used to prepare high conductivity and high bonding strength metal functional films on the surface of various polymer materials such as polyimide and polyether ether ketone.

[0027] This technical solution achieves a smooth transition in composition, structure, and performance between cyanate ester composites and Cu metal films through a continuously varying gradient transition layer. This effectively mitigates the risk of interface failure caused by the mismatch in thermal expansion coefficients between heterogeneous materials, significantly improves the environmental stability and long-term reliability of the interface under complex service conditions such as thermal cycling and humid environments, and greatly expands the application scope of cyanate ester composite substrate metallization structures in high-frequency electronics, aerospace, and other fields. Attached Figure Description

[0028] Figure 1 This is a schematic diagram illustrating the coating principle of the present invention. Detailed Implementation

[0029] In the description of this invention, terminology is used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0030] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the materials, reagents or instruments used, unless otherwise specified by the manufacturer, are all commercially available reagents and materials; the conditions not specified in the examples are all carried out according to conventional conditions or conditions recommended by the manufacturer. At the same time, the present invention does not limit the source of the raw materials used. Unless otherwise specified, the raw materials used in the present invention are all commercially available products in this technical field.

[0031] like Figure 1As shown, the technical solution of this invention first injects high-energy metal particles into the shallow surface layer of a cyanate ester composite material using ion implantation technology, forming a stable internal diffusion source and anchoring point. This provides a stable channel and binding site for the subsequent diffusion and migration of copper film atoms, and also breaks through the technical bottleneck of traditional surface modification, which only acts on the outer surface of the material and has limited effect on improving the bonding force. This lays the foundation for the construction of a strong interfacial bonding structure. By controlling the deposition gas pressure and deposition temperature of plasma coating, a high-purity, high-density Cu metal film with low grain boundary defects can be prepared on the surface of the implanted and modified composite material, which fully ensures the excellent conductivity of the metal film. At the same time, the parameter window of the coating process is compatible with the subsequent heat treatment process. With the low-temperature heat treatment process of 70-100 °C, the controlled migration of implanted metal particles and deposited copper film atoms into the interior of the composite material can be achieved under conditions far below the deformation and decomposition temperature of the cyanate ester composite material. This accurately completes the construction of a continuous gradient transition layer, avoiding irreversible damage to the cyanate ester composite material matrix caused by high-temperature processes throughout the process, and fully preserving the mechanical and dielectric properties of the substrate itself.

[0032] Specifically, plasma activation treatment of the substrate is performed under argon atmosphere using glow discharge or Hall ion source. This cleans the surface and generates active functional groups such as C=O and -NO2, creating an optimized surface chemical environment for subsequent ion implantation and Cu film deposition.

[0033] Simultaneously, high-energy Cu ions were implanted into the shallow surface layer of the cyanate ester composite using ion implantation technology. The implantation energy was selected in the range of 10-25 keV to ensure that copper ions could be doped into the subsurface layer of the composite. The high-energy particle bombardment resulted in numerous fracture sections and nanoscale rough textures on the substrate surface, with a roughness Sa≥30 nm, further increasing the number of mechanical anchor points and contact surface area on the composite surface, providing more bonding sites for subsequent metal atom deposition. The implantation dose was controlled at 1×10⁻⁶. 17 -5×10 17 ions / cm 2 The injection energy and dosage should be adjusted to provide a sufficient diffusion source while avoiding excessive damage to the composite material due to excessive injection energy and dosage.

[0034] Secondly, a dense Cu film is deposited on the surface of the implanted active composite material using physical vapor deposition techniques such as magnetron sputtering and magnetically filtered arc ion plating at low temperature (≤150 ℃) and low pressure (0.1-0.5 Pa). The low temperature aims to prevent thermal deformation of the substrate during deposition, and the low deposition pressure aims to reduce the energy loss of deposited particles caused by particle collisions during deposition, ensuring that the deposited particles maintain high kinetic energy and promoting the migration of Cu atoms on the surface, thereby forming a Cu film with high purity, high density, low grain boundary defects, and electrical properties close to those of the bulk material.

[0035] In addition, the deposited samples were placed in a vacuum oven with a vacuum / venting function for heat treatment, during which impurity gases generated during baking were expelled. The heat treatment temperature was set between 70-100 °C, the heating rate was 5-10 °C / min, and the heat treatment duration was set according to the temperature, ranging from 4-10 h. This temperature is lower than the decomposition temperature of cyanate esters, but it can enhance the chain mobility of cyanate esters. At the same time, it promotes the penetration of injected copper ions and thin film copper atoms at the cyanate ester composite / Cu film interface along the polymer molecular chains or defect channels, and reacts with CC, CO, C=O, and trace adsorbed oxygen in the polymer to generate chemical bonds such as Cu-OC and Cu-NO, as well as a small amount of Cu oxide. Finally, a gradient transition layer with continuously changing composition and chemical state is formed at the interface, realizing a smooth transition from copper-rich to resin-rich, thereby fundamentally improving the bonding strength and interface reliability.

[0036] Example 1 This invention proposes a method for preparing a Cu metal film with high conductivity and high adhesion on the surface of a cyanate ester composite.

[0037] S1. Use a lint-free cloth soaked in anhydrous ethanol to thoroughly rinse the cyanate composite material to remove surface dust, and then dry it with clean air for later use. S2. The sample obtained in S1 is placed in a vacuum chamber and heated at 60 °C for 3 h to remove impurity gases adsorbed in the vacuum chamber and on the surface of the composite material. The vacuum is then evacuated to 1.0 × 10⁻⁶. -3 Pa.

[0038] S3. The composite material obtained in S2 is activated and cleaned using plasma technology for 20 minutes to remove surface impurities and etch the surface. The cleaning source is a Hall ion source.

[0039] S4. Cu ions were implanted into the composite material obtained in S3 using ion implantation technology. The implantation energy was 25 keV, the implantation time was 15 min, and the implantation dose was controlled at 4 × 10⁻⁶. 17 ions / cm 2 Magnitude.

[0040] S5. A Cu metal layer was deposited on the composite material obtained in S4 using magnetic filtering arc ion plating technology. The target material was a Cu metal target with a purity of 99.99%. Ar was introduced as the working gas, the deposition gas pressure was 0.1 Pa, the arc current was 60 A, a bias voltage of -50 V was applied during the deposition process, the deposition time was 3 h, and the film thickness was 1.2 μm. After the Cu metal film deposition was completed, it was cooled for 3 h, the vacuum chamber was vented and the furnace was opened, and the processed composite material was taken out.

[0041] S6. The composite material obtained in S5 is subjected to thermal diffusion treatment using an oven with exhaust function. Impurity gases generated during baking are discharged simultaneously. The baking temperature is 90 ℃ and the baking time is 6 h. After the thermal diffusion treatment is completed, the treated composite material is removed.

[0042] The bonding strength of the cyanate composite / Cu metal film formed through the above process steps is 4.50 MPa.

[0043] Example 2 This invention proposes a method for preparing a Cu metal film with high conductivity and high adhesion on the surface of a cyanate ester composite.

[0044] S1. Use a lint-free cloth soaked in anhydrous ethanol to thoroughly rinse the cyanate composite material to remove surface dust, and then dry it with clean air for later use. S2. Place the sample obtained in S1 in a vacuum chamber and heat it at 60 °C for 1 h to remove the impurity gases adsorbed in the vacuum chamber and on the surface of the composite material. Then, evacuate the vacuum chamber to 0.9 × 10⁻⁶. -3 Below Pa.

[0045] S3. The composite material obtained in S2 is activated and cleaned using plasma technology for 20 minutes to remove surface impurities and etch the surface. The cleaning source is an anodic ion source.

[0046] S4. Cu ions were implanted into the composite material obtained in S3 using ion implantation technology. The implantation energy was 15 keV, the implantation time was 20 min, and the implantation dose was controlled at 5 × 10⁻⁶. 17 ions / cm 2 Magnitude.

[0047] S5. A Cu metal layer was deposited on the composite material obtained in S4 using magnetic filtering arc ion plating technology. The target material was a Cu metal target with a purity of 99.99%. Ar was introduced as the working gas, the deposition gas pressure was 0.5 Pa, the arc current was 50 A, a bias voltage of -100 V was applied during the deposition process, the deposition time was 2 h, and the film thickness was 0.8 μm. After the Cu metal film deposition was completed, it was cooled for 4 h, the vacuum chamber was vented and the furnace was opened, and the processed composite material was taken out.

[0048] S6. The composite material obtained in S5 is subjected to thermal diffusion treatment using an oven with exhaust function. Impurity gases generated during baking are discharged while the material is being heated. The baking temperature is 70 ℃ and the baking time is 10 h. After the thermal diffusion treatment is completed, the treated composite material is removed.

[0049] Example 3 This invention proposes a method for preparing a Cu metal film with high conductivity and high adhesion on the surface of a polyimide composite.

[0050] S1. Use a lint-free cloth soaked in anhydrous ethanol to thoroughly rinse the polyimide composite material to remove surface dust, and then dry it with clean air for later use. S2. The sample obtained in S1 is placed in a vacuum chamber and heated at 60 °C for 3 h to remove impurity gases adsorbed in the vacuum chamber and on the surface of the composite material. The vacuum is then evacuated to 1.0 × 10⁻⁶. -3 Pa.

[0051] S3. The composite material obtained in S2 is activated and cleaned using plasma technology for 20 minutes to remove surface impurities and etch the surface. The cleaning source is a Hall ion source.

[0052] S4. Cu ions were implanted into the composite material obtained in S3 using ion implantation technology. The implantation energy was 20 keV, the implantation time was 5 min, and the implantation dose was controlled at 1×10⁻⁶. 17 ions / cm 2 Magnitude.

[0053] S5. A Cu metal layer was deposited on the composite material obtained in S4 using magnetron sputtering technology. The target material was a Cu metal target with a purity of 99.99%. Ar was introduced as the working gas, the deposition pressure was 0.3 Pa, the power was 1000 W, a bias voltage of -50 V was applied during the deposition process, the deposition time was 1.5 h, and the film thickness was 3.0 μm. After the Cu metal film deposition was completed, it was cooled for 2 h, the vacuum chamber was vented and the furnace was opened, and the processed composite material was taken out.

[0054] S6. The composite material obtained in S5 is subjected to thermal diffusion treatment using an oven with exhaust function. Impurity gases generated during baking are discharged while the material is being heated. The baking temperature is 80 ℃ and the baking time is 7 h. After the thermal diffusion treatment is completed, the treated composite material is removed.

[0055] The bonding strength of the polyimide composite / Cu metal film formed through the above process steps is 4.23 MPa.

[0056] Example 4 This embodiment is basically the same as Embodiment 1, except that it uses polyetheretherketone composite material instead of cyanate ester composite material.

[0057] Comparative Example 1 This comparative example is basically the same as Example 1, except that the processing steps S4 and S6 are missing.

[0058] The adhesion of the cyanate ester composite / Cu metal film without injection and thermal diffusion treatment is 1.56 MPa.

[0059] Comparative Example 2 This comparative example is basically the same as Example 1, except that the processing step S6 is missing.

[0060] The adhesion of the cyanate ester composite / Cu metal film after injection treatment but without thermal diffusion treatment is 2.24 MPa.

[0061] Comparative Example 3 This comparative example is basically the same as Example 3, except that it lacks processing steps S4 and S6.

[0062] The bonding strength of the polyimide composite / Cu metal film without injection and thermal diffusion treatment is 2.48 MPa.

[0063] Comparative Example 4 This comparative example is basically the same as Example 3, except that the processing step S6 is missing.

[0064] The bonding strength of the polyimide composite / Cu metal film after injection treatment but without thermal diffusion treatment is 3.67 MPa.

[0065] It should be noted that the specific embodiments described above are exemplary, and those skilled in the art can devise various solutions inspired by the disclosure of this invention. These solutions all fall within the scope of this invention and its protection. Those skilled in the art should understand that this specification and its accompanying drawings are illustrative and not intended to limit the scope of the claims. The scope of protection of this invention is defined by the claims and their equivalents.

Claims

1. A process for improving the interfacial bonding strength of polymer / metal films, characterized in that, Includes the following steps: 1) Clean the surface of composites made of polyimide, polyetheretherketone, or cyanate ester; 2) Cu ion implantation is performed on the composite material obtained in step 1) using plasma technology, wherein the implantation energy is between 10-25 keV, the implantation time is 5-20 min, and the implantation dose is controlled at 1×10⁻⁶. 17 -5×10 17 ions / cm 2 Magnitude; 3) A Cu metal layer is deposited on the composite material obtained in step 2) using magnetic filtering arc ion plating or magnetron sputtering. The target material is a Cu metal target with a purity of 99.99%. Ar is introduced as the working gas, the deposition gas pressure is between 0.1 and 0.5 Pa, the arc current is between 50 and 70 A, a bias voltage of -50 to -100 V is applied during the deposition process, the deposition time is 2 to 3 h, and the film thickness is between 0.8 and 3.0 μm. 4) Perform thermal diffusion treatment on the composite material from step 3), with a baking temperature of 70-100 ℃ and a baking time of 4-10 h.

2. The process method for improving the interfacial bonding strength of polymer / metal films according to claim 1, characterized in that, Surface cleaning includes wiping with anhydrous ethanol.

3. The process method for improving the interfacial bonding strength of polymer / metal films according to claim 1, characterized in that, Surface cleaning includes vacuum cleaning, the steps of which include: placing the composite material or the composite material wiped clean with anhydrous ethanol in a vacuum chamber and heating and baking it at 60 °C for 1-3 h, and then evacuating the vacuum to 1.0 × 10⁻⁶. -3 Below Pa.

4. The process method for improving the interfacial bonding strength of polymer / metal films according to claim 1, characterized in that, Surface cleaning includes activation cleaning, the activation cleaning step of which includes: treating the composite material with plasma technology, and the cleaning source is selected from one of Hall source ion source, anodic layer ion source or Kaufman ion source.

5. The process method for improving the interfacial bonding strength of polymer / metal films according to claim 1, characterized in that, Step 3) After the metal film deposition is completed, cool for more than 3 hours, release the vacuum chamber and open the furnace to take out the processed composite material.

6. The process method for improving the interfacial bonding strength of polymer / metal films according to claim 1, characterized in that, The metal film is a Cu metal film.

7. A substrate prepared by a process method for improving the interfacial bonding strength of polymer / metal film according to any one of claims 1-6.

8. The substrate according to claim 7, characterized in that, The bonding force between the composite material and the metal film in the substrate is not less than 4.50 MPa.

9. The substrate according to claim 7, characterized in that, The thickness of the metal film in the substrate is 0.8 μm, 1.2 μm, or 3.0 μm.

10. Use of the process for improving the interfacial bonding strength of polymer / metal films according to any one of claims 1-7 in the aerospace field.

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