Aluminum-based composite copper foil heating sheet and method for manufacturing the same

Abstract

The present application relates to the technical field of electronic heat-generating materials and surface treatment, and specifically discloses an aluminum-based composite copper foil heating sheet and a preparation method thereof. The aluminum-based composite copper foil heating sheet comprises a pure aluminum foil substrate, a pretreatment transition layer and a patterned electroplated copper heating layer. The preparation method is compatible with a magnetron sputtering or one-step wet method (degreasing-alkali etching-desmearing-zinc deposition-copper coating) double pretreatment scheme, and a high-precision photoetching is carried out in the subsequent process by using a copper chloride / hydrochloric acid etching liquid system containing a thiourea corrosion inhibitor. The present application effectively solves the problems of weak plating layer adhesion of the existing aluminum copper plating heating sheet and uneven heating caused by easy over-etching. The adhesion of the copper plating layer of the prepared heating sheet to the aluminum substrate reaches 5B level, the line width precision of the conductive heating pattern reaches ±0.01 mm, the heating uniformity deviation is less than or equal to 5%, and the heating sheet has excellent lightweight advantage and long-term stable heating performance, and can be widely applied in the fields of household appliances and industrial heating.

Description

Technical Field

[0001] This invention relates to the field of electronic heating materials and surface treatment technology, specifically to an aluminum-based composite copper foil heating element and its preparation method. Background Technology

[0002] Aluminum-based heating elements are widely used in various heating scenarios, including new energy, smart home appliances, electronic devices, and industrial temperature control, due to their significant advantages such as light weight, good thermal conductivity, and moderate cost. However, pure aluminum has poor electrical conductivity compared to copper. If it is directly used as the conductive heating layer of a heating element, it suffers from inherent defects such as low heating efficiency, localized overheating, and high overall energy consumption. Furthermore, aluminum is highly susceptible to oxidation in air, and the dense oxide film that naturally forms on its surface makes it difficult for subsequent plating layers to bond firmly, severely affecting the lifespan and reliability of the heating element. To address these issues, existing technologies often employ a "copper-plated aluminum" process to modify the aluminum substrate, attempting to significantly improve conductivity through a copper plating layer while maintaining the lightweight advantage of the substrate.

[0003] However, the existing manufacturing process for copper-plated aluminum heating elements still has many technical bottlenecks and shortcomings, specifically in the following aspects: First, the substrate pretreatment solutions are limited and lack adaptability. Existing processes mostly employ only conventional wet pretreatment or magnetron sputtering, which is insufficient to meet the needs of different production scales. For example, the single sputtering process is costly and unsuitable for small- to medium-scale pilot production; while conventional wet treatment is difficult to meet the requirements of high-precision mass production, resulting in a lack of flexibility and compatibility in the production line.

[0004] Secondly, the pretreatment process is not optimized enough, resulting in weak coating adhesion. Existing conventional pretreatment methods are insufficient to completely remove the oxide film on the aluminum foil surface and fail to build an effective transition lattice between aluminum and copper. This leads to extremely weak adhesion between the electroplated copper coating and the aluminum substrate, making it prone to blistering, peeling, and even large-area detachment during subsequent use (especially in alternating hot and cold environments), directly causing the heating element to fail due to open circuit.

[0005] Third, the photolithography etching process suffers from low precision and poor heat uniformity. The performance of the heating element hinges on the precision of its heating pattern. Current processes, when etching the copper layer, are prone to over-etching or lateral etching due to improper control of the chemical system and parameters. This results in significant deviations in the linewidth and spacing of the conductive heating pattern on the heating element. This dimensional inconsistency directly leads to uneven surface resistance distribution, easily generating localized high-temperature points (hot spots) during operation. This not only affects the heating effect but also poses safety hazards.

[0006] Fourth, the process steps are poorly connected and lack environmental friendliness. In the existing process, the parameters of some steps such as film lamination, lamination, micro-etching, and pickling are poorly matched, lacking effective protection for the copper layer surface. This leads to easy oxidation and discoloration of the copper layer, resulting in low product qualification rate and making it difficult to achieve stable industrial mass production. In addition, some existing processes still use etching solutions or electroplating solutions containing cyanide, which are extremely environmentally unfriendly and do not meet the requirements of modern green industrial production.

[0007] Based on the above statements, there is an urgent need to develop an aluminum-based composite copper foil heating element that is compatible with dual pretreatment schemes, has strong coating adhesion, provides uniform and stable heating, has controllable processes, and is environmentally friendly, as well as its preparation method. Summary of the Invention

[0008] To address the technical problems in existing technologies, such as limited pretreatment solutions, insufficient optimization of pretreatment processes, weak coating adhesion, low precision of photolithography and etching processes, poor heat generation uniformity, unreasonable process step connections, and poor environmental friendliness, this invention proposes an aluminum-based composite copper foil heating element and its preparation method.

[0009] In a first aspect, the present invention provides an aluminum-based composite copper foil heating element, which adopts the following technical solution: An aluminum-based composite copper foil heating element includes a pure aluminum foil substrate, a pre-treatment transition layer bonded to the surface of the substrate, and an electroplated copper heating layer deposited on the surface of the pre-treatment transition layer by an electroplating solution; the surface of the electroplated copper heating layer is formed with a heating pattern obtained by etching with an etching solution. The electroplating solution contains the following components at the following concentrations: copper sulfate 180-200 g / L, sulfuric acid 100-120 g / L, chloride ions 40-50 ppm, and copper plating brightener 0.6-0.8 g / L; The etching solution contains the following components at the following concentrations: copper chloride 90-100 g / L, hydrochloric acid 45-50 g / L, and thiourea corrosion inhibitor 0.8-1 g / L.

[0010] Preferably, the thiourea corrosion inhibitor is aminothiourea.

[0011] Preferably, the copper plating brightener is ethylene thiourea.

[0012] Preferably, the pure aluminum foil substrate has a thickness of 0.05mm-0.5mm, a purity of ≥99.9%, and a surface roughness Ra≤0.2μm.

[0013] Preferably, the thickness of the pure aluminum foil substrate is 0.1mm-0.3mm.

[0014] Preferably, the pretreatment transition layer is a copper seed layer with a thickness of 0.1-0.5 μm formed by magnetron sputtering, or a zinc transition layer and a thin copper composite layer formed by one-step wet pretreatment.

[0015] Preferably, the thickness of the electroplated copper heating layer is 1-8 μm.

[0016] Preferably, the heating element further includes an antioxidant protective film formed on the surface of the electroplated copper heating layer; The antioxidant protective film is made of an antioxidant liquid containing: 1.5-2 g / L benzotriazole and 0-0.3 g / L silane coupling agent.

[0017] Preferably, the heating pattern is a conductive heating pattern, and the line width accuracy of the conductive heating pattern is ±0.01mm, and the line spacing accuracy is ±0.02mm.

[0018] Secondly, the present invention provides a method for preparing an aluminum-based composite copper foil heating element, employing the following technical solution: A method for preparing an aluminum-based composite copper foil heating element includes the following steps: S1. Substrate pretreatment: The pure aluminum foil substrate is pretreated to form a pretreatment transition layer on the substrate surface; the pretreatment is performed by magnetron sputtering pretreatment or one-step wet pretreatment. S2. Electroplated copper after treatment: The pretreated substrate is placed in the electroplating solution for electroplating to form an electroplated copper heating layer. Then it is washed with water and subjected to anti-oxidation treatment and dried to obtain electroplated copper after treatment. S3. Photolithography and etching: The treated electroplated copper is subjected to the first film lamination, micro-etching, photolithography dry film lamination, exposure, and development in sequence, and the etching solution is used to etch to form a heating pattern; then the second film lamination and acid washing are performed, and finally the aluminum-based composite copper foil heating sheet is die-cut to obtain the finished product.

[0019] Preferably, the conditions for the magnetron sputtering pretreatment in step S1 are: copper as the target material, and an ultimate vacuum of 3.8 × 10⁻⁶ in the sputtering chamber. -4 Pa -4.2×10 -4 Pa, target-substrate spacing 50-70mm, sputtering temperature 140-160℃, sputtering power 150-250W, sputtering time 2-4min.

[0020] Preferably, the conditions for the magnetron sputtering pretreatment in step S1 are: copper as the target material, and an ultimate vacuum of 4×10⁻⁻⁻⁶ in the sputtering chamber. 4 Pa, target-substrate spacing 60mm, sputtering temperature 150℃, sputtering power 200W, sputtering time 3min.

[0021] Preferably, the wet pretreatment step S1 includes the following steps in sequence: Degreasing: Treat with 50-70 g / L sodium hydroxide and 6-10 g / L surfactant at 50-70℃ for 3-8 min; Alkaline etching: Treat with 20-40 g / L sodium hydroxide at 40-60℃ for 1-3 min; Descaling: Treat with 110-130 g / L nitric acid at 20-30℃ for 30-90 seconds; Zinc precipitation: Treat with 90-110 g / L zinc sulfate and 20-30 g / L ammonium chloride at 20-30℃ for 30-60 seconds; Copper plating: Use 6-10 g / L copper sulfate and 12-18 g / L EDTA at 30-40℃ for 1-2 min, and control the pH value to 9.5-10.5; supplement each process with three-stage water washing.

[0022] Preferably, the wet pretreatment step S1 includes the following steps in sequence: Degreasing: Treat with 60 g / L sodium hydroxide and 8 g / L surfactant at 60°C for 5 min; Alkaline etching: Treat with 30 g / L sodium hydroxide at 50 °C for 2 min; Descaling: Treat with 120 g / L nitric acid at 25°C for 1 min; Zinc precipitation: Treat with 100 g / L zinc sulfate and 25 g / L ammonium chloride at 25°C for 45 seconds; Copper plating: Use 8g / L copper sulfate and 15g / L EDTA to treat at 35℃ for 1.5min, and control the pH value to 10; supplement each process with three-stage water washing.

[0023] Preferably, the electroplating conditions in step S2 are: temperature 20-22℃, current density 4-5A / dm³. 2 Electroplating time: 10-12 minutes.

[0024] Preferably, the water washing in step S2 refers to: three-stage water washing with deionized water, with each stage of water washing lasting 1-2 minutes.

[0025] Preferably, the antioxidant treatment temperature in step S2 is 20-30℃, and the time is 1-3 minutes.

[0026] Preferably, the drying temperature in step S2 is 100-120℃ and the drying time is 3-8 minutes.

[0027] Preferably, in step S3, the first and second film lamination and pressing refer to laminating a PET insulating film or PI insulating film with a thickness of 25-35μm and pressing it at 120-150℃ and 0.3-0.8MPa for 1-3 minutes.

[0028] Preferably, in step S3, the micro-etching is performed using a mixed solution of 50-60 g / L sulfuric acid and 12-15 g / L hydrogen peroxide, treated at 22-25°C for 1-1.5 min.

[0029] Preferably, in step S3, the exposure refers to: exposing to 360-380nm ultraviolet light for 18-22s.

[0030] Preferably, the development in step S3 refers to developing in a NaOH aqueous solution with a mass concentration of 0.8-1.5% for 100-150 seconds.

[0031] Preferably, the drying temperature in step S3 is 100-120℃ and the drying time is 3-8 minutes.

[0032] Preferably, in step S3, pickling refers to immersing the sample in a sulfuric acid solution with a mass concentration of 5-10% for 30-60 seconds.

[0033] Preferably, the die-cutting pressure in step S3 is 5-10 MPa.

[0034] Preferably, the etching conditions in step S3 are a temperature of 38-40°C and a time of 5-6 minutes.

[0035] In summary, the present invention has the following beneficial effects: (1) High compatibility of pretreatment schemes: The present invention designs two pretreatment schemes: magnetron sputtering and one-step wet process. The two schemes can be flexibly selected according to the production scale (large-scale mass production / small-scale trial production) and the existing production line conditions. The schemes are highly adaptable and solve the problem of the single process scheme in the existing process.

[0036] (2) Strong coating adhesion: By optimizing the pretreatment process and electroplating parameters, the adhesion between the copper coating and the aluminum substrate is ≥5B grade (100-grid test). There is no coating peeling or falling off during use, and the service life is extended by more than 30% compared with existing products.

[0037] (3) Uniform and stable heating: Through high-precision photolithography etching process, the line width and line spacing of the conductive heating pattern of the heating sheet are highly accurate, the heating uniformity deviation is ≤5%, and there is no local overheating phenomenon; the copper plating has excellent conductivity, surface resistance is ≤0.05Ω / in, and the heating efficiency is improved by more than 20%.

[0038] (4) Stable and environmentally friendly process: The parameters of each process are precisely matched and the steps are reasonably connected. The product qualification rate can reach more than 98%, which is convenient for large-scale industrial production. The use of cyanide-free environmentally friendly electroplating solution, etching solution and antioxidants meets the requirements of modern industrial green production.

[0039] (5) Wide product adaptability: The prepared aluminum-copper-plated heating element is lightweight, has good thermal conductivity and strong corrosion resistance, and can be widely used in many fields such as home appliances, electronic equipment, and industrial heating, with broad market application prospects. Detailed Implementation

[0040] The present invention will be further described in detail below with reference to the embodiments.

[0041] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0042] Examples 1-6 provide an aluminum-based composite copper foil heating element and its preparation method.

[0043] Example 1 A method for preparing an aluminum-based composite copper foil heating element includes the following steps: S1. Substrate Selection and Pretreatment: Pure aluminum foil with a thickness of 0.1 mm and a purity of 99.95% was selected as the substrate (Ra = 0.1 μm). It was placed in a magnetron sputtering apparatus with copper as the target material and an ultimate vacuum of 3.8 × 10⁻⁶. -4 Pa, target-substrate spacing 50 mm, sputtering temperature 140 °C, sputtering power 150 W, sputtering time 4 min, deposit a copper seed layer with a thickness of 0.1 μm on the substrate surface.

[0044] S2. Copper plating and anti-oxidation: The pretreated substrate is placed into the copper plating bath. The plating solution consists of: copper sulfate 180g / L, sulfuric acid 100g / L, chloride ions 40ppm, and ethylene thiourea 0.6g / L. The temperature is 20℃, and the current density is 4A / dm³. 2 Electroplating was performed for 12 minutes to form a 1 μm thick copper heating layer. The copper was then rinsed three times with deionized water, each rinse lasting 1 minute. Afterward, the copper was immersed in an antioxidant solution (containing 1.5 g / L benzotriazole) at 20°C for 3 minutes. Finally, it was dried at 100°C for 8 minutes, with the winding tension controlled at 5 N, and wound smoothly to obtain the treated electroplated copper.

[0045] S3. Photolithography, Etching, and Shaping: The treated electroplated copper undergoes a first film lamination process, laminating a 25μm thick PET insulating film at 120℃ and 0.3MPa for 3 minutes. Subsequently, a micro-etching process is performed at 22℃ for 1.5 minutes using a mixed solution of 50g / L sulfuric acid and 12g / L hydrogen peroxide. Following this, a photolithographic dry film is uniformly laminated at 85℃ and exposed to 360nm UV light for 22 seconds. Development is then performed in a 0.8% NaOH aqueous solution for 150 seconds. The developed material is then immersed in an etching solution (containing 90g / L copper chloride, 45g / L hydrochloric acid, and 0.8g / L aminothiourea) and etched at 38℃ for 6 minutes to form a conductive heating pattern. The conductive heating pattern is laminated a second time with a 25μm thick PET insulating film. The lamination is carried out at 120℃ and 0.3MPa for 3 minutes, dried at 100℃ for 8 minutes, and finally immersed in a 5% sulfuric acid solution for 60 seconds. After the acid washing is completed, it is die-cut into shape under a pressure of 5MPa to obtain an aluminum-based composite copper foil heating sheet.

[0046] Example 2 A method for preparing an aluminum-based composite copper foil heating element includes the following steps: S1. Substrate Selection and Pretreatment: Pure aluminum foil with a thickness of 0.2 mm and a purity of 99.95% was selected as the substrate (Ra = 0.15 μm). It was placed in a magnetron sputtering apparatus with copper as the target material and an ultimate vacuum of 4 × 10⁻⁶. -4 Pa, target-substrate spacing 60 mm, sputtering temperature 150 °C, sputtering power 200 W, sputtering time 3 min, deposit a copper seed layer with a thickness of 0.3 μm on the substrate surface.

[0047] S2. Copper plating and anti-oxidation: The pretreated substrate is placed into a copper plating bath. The plating solution consists of: copper sulfate 190 g / L, sulfuric acid 110 g / L, chloride ions 45 ppm, and ethylene thiourea 0.7 g / L. The plating temperature is 21℃, and the current density is 4.5 A / dm³. 2 Electroplating was performed for 11 minutes to form a 4 μm thick copper heating layer. After a three-stage rinsing with deionized water (1.5 minutes per stage), the copper was immersed in an antioxidant solution (containing 1.8 g / L benzotriazole and 0.2 g / L silane coupling agent) at 25°C for 2 minutes. Subsequently, the copper was dried at 110°C for 5 minutes, with a winding tension of 10 N, and smoothly wound up to obtain the treated electroplated copper.

[0048] S3. Photolithography, Etching, and Shaping: The treated electroplated copper undergoes a first film lamination process, laminating a 30μm thick PET insulating film at 135℃ and 0.5MPa for 2 minutes. Subsequently, a micro-etching process is performed at 23.5℃ for 1.2 minutes using a mixed solution of 55g / L sulfuric acid and 13.5g / L hydrogen peroxide. Following this, a photolithographic dry film is uniformly laminated at 90℃ and exposed to 370nm UV light for 20 seconds. Development is then performed in a 1.2% NaOH aqueous solution for 125 seconds. The developed material is then immersed in an etching solution (containing 95g / L copper chloride, 48g / L hydrochloric acid, and 0.9g / L aminothiourea) and etched at 39℃ for 5.5 minutes to form a conductive heating pattern. The conductive heating pattern is laminated a second time with a 30μm thick PET insulating film. The lamination is carried out at 135℃ and 0.5MPa for 2 minutes, dried at 110℃ for 5 minutes, and finally immersed in an 8% sulfuric acid solution for 45 seconds. After the acid washing is completed, it is die-cut into shape under a pressure of 7MPa to obtain an aluminum-based composite copper foil heating element.

[0049] Example 3 A method for preparing an aluminum-based composite copper foil heating element includes the following steps: S1. Substrate Selection and Pretreatment: Pure aluminum foil with a thickness of 0.3 mm and a purity of 99.95% was selected as the substrate (Ra = 0.2 μm). It was placed in a magnetron sputtering apparatus with copper as the target material and an ultimate vacuum of 4.2 × 10⁻⁶. -4 Pa, target-substrate spacing 70 mm, sputtering temperature 160 °C, sputtering power 250 W, sputtering time 2 min, deposit a copper seed layer with a thickness of 0.5 μm on the substrate surface.

[0050] S2. Copper plating and anti-oxidation: The pretreated substrate is placed into a copper plating bath. The plating solution consists of: copper sulfate 200g / L, sulfuric acid 120g / L, chloride ion 50ppm, and ethylene thiourea 0.8g / L. The plating temperature is 22℃, and the current density is 5A / dm³. 2 Electroplating was performed for 10 minutes to form an 8 μm thick copper heating layer. The copper was then rinsed three times with deionized water, each rinse lasting 2 minutes. Afterward, the copper was immersed in an antioxidant solution (containing 2 g / L benzotriazole and 0.3 g / L silane coupling agent) at 30°C for 1 minute. Finally, it was dried at 120°C for 3 minutes, with the winding tension controlled at 15 N, and wound smoothly to obtain the treated electroplated copper.

[0051] S3. Photolithography, Etching, and Shaping: The treated electroplated copper undergoes a first film lamination process, laminating a 35μm thick PET insulating film at 150℃ and 0.8MPa for 1 min. Subsequently, a micro-etching process is performed at 25℃ for 1 min using a mixed solution of 60g / L sulfuric acid and 15g / L hydrogen peroxide. Following this, a photolithographic dry film is uniformly laminated at 95℃ and exposed to 380nm UV light for 18 s. Development is then performed in a 1.5% NaOH aqueous solution for 100 s. The developed material is then immersed in an etching solution (containing 100g / L copper chloride, 50g / L hydrochloric acid, and 1g / L aminothiourea) and etched at 40℃ for 5 min to form a conductive heating pattern. The conductive heating pattern is laminated a second time with a 35μm thick PET insulating film. The lamination is carried out at 150℃ and 0.8MPa for 1 min, dried at 120℃ for 3 min, and finally immersed in a 10% sulfuric acid solution for 30 s for pickling. After pickling, it is die-cut into shape under 10MPa pressure to obtain an aluminum-based composite copper foil heating element.

[0052] Example 4 A method for preparing an aluminum-based composite copper foil heating element includes the following steps: S1. Substrate selection and pretreatment: Select pure aluminum foil with a thickness of 0.1 mm and a purity of 99.95% as the substrate (Ra=0.1μm). The following wet pretreatment steps were performed sequentially: ① Degreasing: Treatment with 50 g / L sodium hydroxide and 6 g / L surfactant at 50℃ for 8 min; ② Three-stage water washing with deionized water, each stage lasting 1 min; ③ Alkali etching: Treatment with 20 g / L sodium hydroxide at 40℃ for 3 min; ④ Three-stage water washing with deionized water, each stage lasting 1 min; ⑤ Descaling: Treatment with 110 g / L nitric acid at 20℃ for 90 s; ⑥ Three-stage water washing with deionized water, each stage lasting 1 min; ⑦ Zinc precipitation: Treatment with 90 g / L zinc sulfate and 20 g / L ammonium chloride at 20℃ for 60 s; ⑧ Three-stage water washing with deionized water, each stage lasting 1 min; ⑨ Copper plating: Treatment with 6 g / L copper sulfate and 12 g / L EDTA at 30℃ for 2 min, controlling the pH value to 9.5; A zinc transition layer and a thin copper composite layer with a thickness of 0.1 μm were deposited on the substrate surface.

[0053] S2. Copper plating and anti-oxidation: The pretreated substrate is placed into the copper plating bath. The plating solution consists of: copper sulfate 180g / L, sulfuric acid 100g / L, chloride ions 40ppm, and ethylene thiourea 0.6g / L. The temperature is 20℃, and the current density is 4A / dm³. 2Electroplating was performed for 12 minutes to form a 1 μm thick copper heating layer. The copper was then rinsed three times with deionized water, each rinse lasting 1 minute. Afterward, the copper was immersed in an antioxidant solution (containing 1.5 g / L benzotriazole) at 20°C for 3 minutes. Finally, it was dried at 100°C for 8 minutes, with the winding tension controlled at 5 N, and wound smoothly to obtain the treated electroplated copper.

[0054] S3. Photolithography, Etching, and Shaping: The treated electroplated copper undergoes a first film lamination process, laminating a 25μm thick PET insulating film at 120℃ and 0.3MPa for 3 minutes. Subsequently, a micro-etching process is performed at 22℃ for 1.5 minutes using a mixed solution of 50g / L sulfuric acid and 12g / L hydrogen peroxide. Following this, a photolithographic dry film is uniformly laminated at 85℃ and exposed to 360nm UV light for 22 seconds. Development is then performed in a 0.8% NaOH aqueous solution for 150 seconds. The developed material is then immersed in an etching solution (containing 90g / L copper chloride, 45g / L hydrochloric acid, and 0.8g / L aminothiourea) and etched at 38℃ for 6 minutes to form a conductive heating pattern. The conductive heating pattern is laminated a second time with a 25μm thick PET insulating film. The lamination is carried out at 120℃ and 0.3MPa for 3 minutes, dried at 100℃ for 8 minutes, and finally immersed in a 5% sulfuric acid solution for 60 seconds. After the acid washing is completed, it is die-cut into shape under a pressure of 5MPa to obtain an aluminum-based composite copper foil heating sheet.

[0055] Example 5 A method for preparing an aluminum-based composite copper foil heating element includes the following steps: S1. Substrate selection and pretreatment: Select pure aluminum foil with a thickness of 0.2 mm and a purity of 99.95% as the substrate (Ra=0.15μm). The following wet pretreatment steps were performed sequentially: ① Degreasing: Treatment with 60 g / L sodium hydroxide and 8 g / L surfactant at 60℃ for 5 min; ② Three-stage water washing with deionized water, each stage lasting 1 min; ③ Alkali etching: Treatment with 30 g / L sodium hydroxide at 50℃ for 2 min; ④ Three-stage water washing with deionized water, each stage lasting 1 min; ⑤ Descaling: Treatment with 120 g / L nitric acid at 25℃ for 60 s; ⑥ Three-stage water washing with deionized water, each stage lasting 1 min; ⑦ Zinc precipitation: Treatment with 100 g / L zinc sulfate and 25 g / L ammonium chloride at 25℃ for 45 s; ⑧ Three-stage water washing with deionized water, each stage lasting 1 min; ⑨ Copper plating: Treatment with 8 g / L copper sulfate and 15 g / L EDTA at 35℃ for 1.5 min, controlling the pH value to 10; A zinc transition layer and a thin copper composite layer with a thickness of 0.3 μm were deposited on the substrate surface.

[0056] S2. Copper plating and anti-oxidation: The pretreated substrate is placed into a copper plating bath. The plating solution consists of: copper sulfate 190 g / L, sulfuric acid 110 g / L, chloride ions 45 ppm, and ethylene thiourea 0.7 g / L. The plating temperature is 21℃, and the current density is 4.5 A / dm³. 2 Electroplating was performed for 11 minutes to form a 4 μm thick copper heating layer. After a three-stage rinsing with deionized water (1.5 minutes per stage), the copper was immersed in an antioxidant solution (containing 1.8 g / L benzotriazole and 0.2 g / L silane coupling agent) at 25°C for 2 minutes. Subsequently, the copper was dried at 110°C for 5 minutes, with a winding tension of 10 N, and smoothly wound up to obtain the treated electroplated copper.

[0057] S3. Photolithography, Etching, and Shaping: The treated electroplated copper undergoes a first film lamination process, laminating a 30μm thick PET insulating film at 135℃ and 0.5MPa for 2 minutes. Subsequently, a micro-etching process is performed at 23.5℃ for 1.2 minutes using a mixed solution of 55g / L sulfuric acid and 13.5g / L hydrogen peroxide. Following this, a photolithographic dry film is uniformly laminated at 90℃ and exposed to 370nm UV light for 20 seconds. Development is then performed in a 1.2% NaOH aqueous solution for 125 seconds. The developed material is then immersed in an etching solution (containing 95g / L copper chloride, 48g / L hydrochloric acid, and 0.9g / L aminothiourea) and etched at 39℃ for 5.5 minutes to form a conductive heating pattern. The conductive heating pattern is laminated a second time with a 30μm thick PET insulating film. The lamination is carried out at 135℃ and 0.5MPa for 2 minutes, dried at 110℃ for 5 minutes, and finally immersed in an 8% sulfuric acid solution for 45 seconds. After the acid washing is completed, it is die-cut into shape under a pressure of 7MPa to obtain an aluminum-based composite copper foil heating element.

[0058] Example 6 A method for preparing an aluminum-based composite copper foil heating element includes the following steps: S1. Substrate selection and pretreatment: Select pure aluminum foil with a thickness of 0.3 mm and a purity of 99.95% as the substrate (Ra=0.2μm). The following wet pretreatment steps were performed sequentially: ① Degreasing: Treat with 70 g / L sodium hydroxide and 10 g / L surfactant at 70℃ for 3 min; ② Three-stage water washing with deionized water, each stage lasting 1 min; ③ Alkali etching: Treat with 40 g / L sodium hydroxide at 60℃ for 1 min; ④ Three-stage water washing with deionized water, each stage lasting 1 min; ⑤ Descaling: Treat with 130 g / L nitric acid at 30℃ for 30 s; ⑥ Three-stage water washing with deionized water, each stage lasting 1 min; ⑦ Zinc precipitation: Treat with 110 g / L zinc sulfate and 30 g / L ammonium chloride at 30℃ for 30 s; ⑧ Three-stage water washing with deionized water, each stage lasting 1 min; ⑨ Copper plating: Treat with 10 g / L copper sulfate and 18 g / L EDTA at 40℃ for 1 min, controlling the pH value to 10.5; A zinc transition layer and a thin copper composite layer with a thickness of 0.5 μm were deposited on the substrate surface.

[0059] S2. Copper plating and anti-oxidation: The pretreated substrate is placed into a copper plating bath. The plating solution consists of: copper sulfate 200g / L, sulfuric acid 120g / L, chloride ion 50ppm, and ethylene thiourea 0.8g / L. The plating temperature is 22℃, and the current density is 5A / dm³. 2 Electroplating was performed for 10 minutes to form an 8 μm thick copper heating layer. The copper was then rinsed three times with deionized water, each rinse lasting 2 minutes. Afterward, the copper was immersed in an antioxidant solution (containing 2 g / L benzotriazole and 0.3 g / L silane coupling agent) at 30°C for 1 minute. Finally, it was dried at 120°C for 3 minutes, with the winding tension controlled at 15 N, and wound smoothly to obtain the treated electroplated copper.

[0060] S3. Photolithography, Etching, and Shaping: The treated electroplated copper undergoes a first film lamination process, laminating a 35μm thick PET insulating film at 150℃ and 0.8MPa for 1 min. Subsequently, a micro-etching process is performed at 25℃ for 1 min using a mixed solution of 60g / L sulfuric acid and 15g / L hydrogen peroxide. Following this, a photolithographic dry film is uniformly laminated at 95℃ and exposed to 380nm UV light for 18 s. Development is then performed in a 1.5% NaOH aqueous solution for 100 s. The developed material is then immersed in an etching solution (containing 100g / L copper chloride, 50g / L hydrochloric acid, and 1g / L aminothiourea) and etched at 40℃ for 5 min to form a conductive heating pattern. The conductive heating pattern is laminated a second time with a 35μm thick PET insulating film. The lamination is carried out at 150℃ and 0.8MPa for 1 min, dried at 120℃ for 3 min, and finally immersed in a 10% sulfuric acid solution for 30 s for pickling. After pickling, it is die-cut into shape under 10MPa pressure to obtain an aluminum-based composite copper foil heating element.

[0061] To verify the comprehensive performance of the aluminum-based composite copper foil heating element provided by this invention, comparative examples 1-4 were set up, wherein: Comparative Example 1 Comparative Example 1 is the same as Example 6, except that the "zinc immersion" and "copper plating" processes are omitted in step S1. Instead, the aluminum foil is directly subjected to "degreasing-alkaline etching-descaling" and water washing before proceeding directly to step S2, copper electroplating. Details are as follows: A method for preparing an aluminum-based composite copper foil heating element includes the following steps: S1. Substrate Selection and Pretreatment: Pure aluminum foil with a thickness of 0.3 mm and a purity of 99.95% was selected as the substrate (Ra=0.2μm). A one-step wet pretreatment process was performed sequentially: ① Degreasing: Treatment with 70 g / L sodium hydroxide and 10 g / L surfactant at 70℃ for 3 min; ② Three-stage water washing with deionized water, each stage lasting 1 min; ③ Alkali etching: Treatment with 40 g / L sodium hydroxide at 60℃ for 1 min; ④ Three-stage water washing with deionized water, each stage lasting 1 min; ⑤ Descaling: Treatment with 130 g / L nitric acid at 30℃ for 30 s; ⑥ Three-stage water washing with deionized water, each stage lasting 1 min, to obtain the pretreated substrate.

[0062] S2. Copper plating and anti-oxidation: The pretreated substrate is placed into a copper plating bath. The plating solution consists of: copper sulfate 200g / L, sulfuric acid 120g / L, chloride ion 50ppm, and ethylene thiourea 0.8g / L. The plating temperature is 22℃, and the current density is 5A / dm³. 2 Electroplating was performed for 10 minutes to form an 8 μm thick copper heating layer. The copper was then rinsed three times with deionized water, each rinse lasting 2 minutes. Afterward, the copper was immersed in an antioxidant solution (containing 2 g / L benzotriazole and 0.3 g / L silane coupling agent) at 30°C for 1 minute. Finally, it was dried at 120°C for 3 minutes, with the winding tension controlled at 15 N, and wound smoothly to obtain the treated electroplated copper.

[0063] S3. Photolithography, Etching, and Shaping: The treated electroplated copper undergoes a first film lamination process, laminating a 35μm thick PET insulating film at 150℃ and 0.8MPa for 1 min. Subsequently, a micro-etching process is performed at 25℃ for 1 min using a mixed solution of 60g / L sulfuric acid and 15g / L hydrogen peroxide. Following this, a photolithographic dry film is uniformly laminated at 95℃ and exposed to 380nm UV light for 18 s. Development is then performed in a 1.5% NaOH aqueous solution for 100 s. The developed material is then immersed in an etching solution (containing 100g / L copper chloride, 50g / L hydrochloric acid, and 1g / L aminothiourea) and etched at 40℃ for 5 min to form a conductive heating pattern. The conductive heating pattern is laminated a second time with a 35μm thick PET insulating film. The lamination is carried out at 150℃ and 0.8MPa for 1 min, dried at 120℃ for 3 min, and finally immersed in a 10% sulfuric acid solution for 30 s for pickling. After pickling, it is die-cut into shape under 10MPa pressure to obtain an aluminum-based composite copper foil heating element.

[0064] Comparative Example 2 Comparative Example 2 is the same as Example 6, except that the antioxidant treatment containing benzotriazole and silane coupling agent is omitted in step S2, and the product is directly dried at 120°C after washing. Details are as follows: A method for preparing an aluminum-based composite copper foil heating element includes the following steps: S1. Substrate selection and pretreatment: Select pure aluminum foil with a thickness of 0.3 mm and a purity of 99.95% as the substrate (Ra=0.2μm). The following wet pretreatment steps were performed sequentially: ① Degreasing: Treat with 70 g / L sodium hydroxide and 10 g / L surfactant at 70℃ for 3 min; ② Three-stage water washing with deionized water, each stage lasting 1 min; ③ Alkali etching: Treat with 40 g / L sodium hydroxide at 60℃ for 1 min; ④ Three-stage water washing with deionized water, each stage lasting 1 min; ⑤ Descaling: Treat with 130 g / L nitric acid at 30℃ for 30 s; ⑥ Three-stage water washing with deionized water, each stage lasting 1 min; ⑦ Zinc precipitation: Treat with 110 g / L zinc sulfate and 30 g / L ammonium chloride at 30℃ for 30 s; ⑧ Three-stage water washing with deionized water, each stage lasting 1 min; ⑨ Copper plating: Treat with 10 g / L copper sulfate and 18 g / L EDTA at 40℃ for 1 min, controlling the pH value to 10.5; A zinc transition layer and a thin copper composite layer with a thickness of 0.5 μm were deposited on the substrate surface.

[0065] S2. Copper plating and anti-oxidation: The pretreated substrate is placed into a copper plating bath. The plating solution consists of: copper sulfate 200g / L, sulfuric acid 120g / L, chloride ion 50ppm, and ethylene thiourea 0.8g / L. The plating temperature is 22℃, and the current density is 5A / dm³. 2Electroplating was performed for 10 minutes to form an 8μm thick copper heating layer. The copper was then rinsed three times with deionized water, each rinse lasting 2 minutes. Afterward, it was dried at 120℃ for 3 minutes, with the winding tension controlled at 15N, and wound smoothly to obtain the treated electroplated copper.

[0066] S3. Photolithography, Etching, and Shaping: The treated electroplated copper undergoes a first film lamination process, laminating a 35μm thick PET insulating film at 150℃ and 0.8MPa for 1 min. Subsequently, a micro-etching process is performed at 25℃ for 1 min using a mixed solution of 60g / L sulfuric acid and 15g / L hydrogen peroxide. Following this, a photolithographic dry film is uniformly laminated at 95℃ and exposed to 380nm UV light for 18 s. Development is then performed in a 1.5% NaOH aqueous solution for 100 s. The developed material is then immersed in an etching solution (containing 100g / L copper chloride, 50g / L hydrochloric acid, and 1g / L aminothiourea) and etched at 40℃ for 5 min to form a conductive heating pattern. The conductive heating pattern is laminated a second time with a 35μm thick PET insulating film. The lamination is carried out at 150℃ and 0.8MPa for 1 min, dried at 120℃ for 3 min, and finally immersed in a 10% sulfuric acid solution for 30 s for pickling. After pickling, it is die-cut into shape under 10MPa pressure to obtain an aluminum-based composite copper foil heating element.

[0067] Comparative Example 3 Comparative Example 3 is the same as Example 6, except that the micro-etching process is omitted in step S3, and the photolithographic dry film is directly applied after the first protective film is laminated. Details are as follows: A method for preparing an aluminum-based composite copper foil heating element includes the following steps: S1. Substrate selection and pretreatment: Select pure aluminum foil with a thickness of 0.3 mm and a purity of 99.95% as the substrate (Ra=0.2μm). The following wet pretreatment steps were performed sequentially: ① Degreasing: Treat with 70 g / L sodium hydroxide and 10 g / L surfactant at 70℃ for 3 min; ② Three-stage water washing with deionized water, each stage lasting 1 min; ③ Alkali etching: Treat with 40 g / L sodium hydroxide at 60℃ for 1 min; ④ Three-stage water washing with deionized water, each stage lasting 1 min; ⑤ Descaling: Treat with 130 g / L nitric acid at 30℃ for 30 s; ⑥ Three-stage water washing with deionized water, each stage lasting 1 min; ⑦ Zinc precipitation: Treat with 110 g / L zinc sulfate and 30 g / L ammonium chloride at 30℃ for 30 s; ⑧ Three-stage water washing with deionized water, each stage lasting 1 min; ⑨ Copper plating: Treat with 10 g / L copper sulfate and 18 g / L EDTA at 40℃ for 1 min, controlling the pH value to 10.5; A zinc transition layer and a thin copper composite layer with a thickness of 0.5 μm were deposited on the substrate surface.

[0068] S2. Copper plating and anti-oxidation: The pretreated substrate is placed into a copper plating bath. The plating solution consists of: copper sulfate 200g / L, sulfuric acid 120g / L, chloride ion 50ppm, and ethylene thiourea 0.8g / L. The plating temperature is 22℃, and the current density is 5A / dm³. 2 Electroplating was performed for 10 minutes to form an 8 μm thick copper heating layer. The copper was then rinsed three times with deionized water, each rinse lasting 2 minutes. Afterward, the copper was immersed in an antioxidant solution (containing 2 g / L benzotriazole and 0.3 g / L silane coupling agent) at 30°C for 1 minute. Finally, it was dried at 120°C for 3 minutes, with the winding tension controlled at 15 N, and wound smoothly to obtain the treated electroplated copper.

[0069] S3. Photolithography, Etching, and Shaping: The treated electroplated copper undergoes a first film lamination process, laminating a 35μm thick PET insulating film at 150℃ and 0.8MPa for 1 min. Subsequently, a photolithographic dry film is uniformly laminated at 95℃ and exposed to 380nm UV light for 18 s. Development is then performed in a 1.5% NaOH aqueous solution for 100 s. The developed material is then immersed in an etching solution (containing 100g / L copper chloride, 50g / L hydrochloric acid, and 1g / L aminothiourea) and etched at 40℃ for 5 min to form a conductive heating pattern. A second film lamination process is performed on the conductive heating pattern, laminating a 35μm thick PET insulating film at 150℃ and 0.8MPa for 1 min, followed by drying at 120℃ for 3 min. Finally, the material is immersed in a 10% sulfuric acid solution for 30 s for acid washing. After acid washing, it is die-cut at 10MPa pressure to obtain an aluminum-based composite copper foil heating element.

[0070] Comparative Example 4 Comparative Example 4 is the same as Example 6, except that the etching solution in step S3 does not contain aminothiourea, but only 100 g / L copper chloride and 50 g / L hydrochloric acid. Details are as follows: A method for preparing an aluminum-based composite copper foil heating element includes the following steps: S1. Substrate selection and pretreatment: Select pure aluminum foil with a thickness of 0.3 mm and a purity of 99.95% as the substrate (Ra=0.2μm). The following wet pretreatment steps were performed sequentially: ① Degreasing: Treat with 70 g / L sodium hydroxide and 10 g / L surfactant at 70℃ for 3 min; ② Three-stage water washing with deionized water, each stage lasting 1 min; ③ Alkali etching: Treat with 40 g / L sodium hydroxide at 60℃ for 1 min; ④ Three-stage water washing with deionized water, each stage lasting 1 min; ⑤ Descaling: Treat with 130 g / L nitric acid at 30℃ for 30 s; ⑥ Three-stage water washing with deionized water, each stage lasting 1 min; ⑦ Zinc precipitation: Treat with 110 g / L zinc sulfate and 30 g / L ammonium chloride at 30℃ for 30 s; ⑧ Three-stage water washing with deionized water, each stage lasting 1 min; ⑨ Copper plating: Treat with 10 g / L copper sulfate and 18 g / L EDTA at 40℃ for 1 min, controlling the pH value to 10.5; A zinc transition layer and a thin copper composite layer with a thickness of 0.5 μm were deposited on the substrate surface.

[0071] S2. Copper plating and anti-oxidation: The pretreated substrate is placed into a copper plating bath. The plating solution consists of: copper sulfate 200g / L, sulfuric acid 120g / L, chloride ion 50ppm, and ethylene thiourea 0.8g / L. The plating temperature is 22℃, and the current density is 5A / dm³. 2 Electroplating was performed for 10 minutes to form an 8 μm thick copper heating layer. The copper was then rinsed three times with deionized water, each rinse lasting 2 minutes. Afterward, the copper was immersed in an antioxidant solution (containing 2 g / L benzotriazole and 0.3 g / L silane coupling agent) at 30°C for 1 minute. Finally, it was dried at 120°C for 3 minutes, with the winding tension controlled at 15 N, and wound smoothly to obtain the treated electroplated copper.

[0072] S3. Photolithography, Etching, and Shaping: The treated electroplated copper undergoes a first film lamination process, laminating a 35μm thick PET insulating film at 150℃ and 0.8MPa for 1 min. Subsequently, a micro-etching treatment is performed at 25℃ for 1 min using a mixed solution of 60g / L sulfuric acid and 15g / L hydrogen peroxide. Following this, a photolithographic dry film is uniformly laminated at 95℃ and exposed to 380nm UV light for 18 s. Development is then performed in a 1.5% NaOH aqueous solution for 100 s. The developed material is then immersed in an etching solution (containing 100g / L copper chloride and 50g / L hydrochloric acid) and etched at 40℃ for 5 min to form a conductive heating pattern. The conductive heating pattern is laminated a second time with a 35μm thick PET insulating film. The lamination is carried out at 150℃ and 0.8MPa for 1 min, dried at 120℃ for 3 min, and finally immersed in a 10% sulfuric acid solution for 30 s for pickling. After pickling, it is die-cut into shape under 10MPa pressure to obtain an aluminum-based composite copper foil heating element.

[0073] The comprehensive performance of the aluminum-based composite copper foil heating elements prepared in Examples 1-6 and Comparative Examples 1-4 of this invention was tested respectively.

[0074] Coating adhesion: Performed according to ASTM D3359 cross-cut adhesion test (5B means no peeling, 0B means complete peeling).

[0075] Line width accuracy deviation: The deviation between the line width of the etched conductive heating pattern and the design value is measured using a 2D image measuring instrument.

[0076] Line spacing accuracy deviation: The deviation between the line spacing of the etched conductive heating pattern and the design value is measured using a two-dimensional image measuring instrument.

[0077] Heating uniformity deviation: After powering on, use an infrared thermal imager to measure the temperature at multiple points on the surface of the heating element, and calculate the percentage deviation between the highest and lowest temperatures.

[0078] Surface resistance: The sheet resistance of the copper-plated heating layer on the heating element was measured using a four-probe surface resistance meter at 25°C.

[0079] High-temperature aging: The sample was placed in a 100℃ environmental chamber and heated continuously for 1000 hours. The appearance was observed for oxidation discoloration, blistering or peeling of the coating, and the surface resistivity change rate before and after aging was measured.

[0080] The test results are shown in Table 1: Table 1: Comprehensive performance test data of aluminum-based composite copper foil heating elements in Examples 1-6 and Comparative Examples 1-4 As shown in Table 1, the aluminum-based composite copper foil heating elements prepared in Examples 1-6 of this invention all exhibit excellent comprehensive performance. Their coating adhesion reaches level 5B, the line width and line spacing accuracy are controlled within a very small deviation range, the heating uniformity deviation is ≤4.0%, and they have low surface resistance and excellent high-temperature aging resistance. Their comprehensive performance is significantly better than that of Comparative Examples 1-4.

[0081] As can be seen from Example 1 and Comparative Example 1, when using wet pretreatment, omitting the "zinc immersion" and "copper plating" processes will result in incomplete removal of the oxide film on the surface of the aluminum substrate and the inability to form an effective transition lattice layer. This will cause the adhesion between the subsequent electroplated copper layer and the aluminum substrate to drop sharply to level 1B, resulting in localized peeling of the plating layer during high-temperature aging tests, which will seriously affect the structural stability and service life of the heating element.

[0082] As shown in Example 1 and Comparative Example 2, omitting the anti-oxidation treatment process containing benzotriazole and silane coupling agent after copper electroplating makes the exposed copper heating layer highly susceptible to oxidation during subsequent high-temperature processes and aging tests. The formation of surface oxides leads to a significant increase in the surface resistance of the product, and the resistance change rate after aging exceeds 25%, failing to guarantee long-term stable electrothermal conversion performance.

[0083] As can be seen from Example 1 and Comparative Example 3, omitting the micro-etching process before the photolithography step results in insufficient surface roughness of the electroplated copper layer and a decrease in the adhesion between the photolithographic dry film and the copper layer surface. This easily leads to micro-leakage of the dry film during development and etching, resulting in a significant increase in the deviation of the line width and line spacing accuracy after etching, and consequently, a decrease in the uniformity of surface heating.

[0084] As shown in Example 1 and Comparative Example 4, without the addition of aminothiourea to the etching solution, the single copper chloride / hydrochloric acid system resulted in an excessively rapid lateral etching rate of the copper layer, leading to severe "lateral etching" or "over-etching." This directly caused severe loss of control over the linewidth and spacing of the conductive heating pattern, and the uneven distribution of the cross-sectional area resulted in severe local hot spots, causing the heating uniformity deviation to surge to 11.2%, posing a significant safety hazard.

[0085] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. An aluminum-based composite copper foil heating element, characterized in that, It includes a pure aluminum foil substrate, a pre-treatment transition layer bonded to the surface of the substrate, and an electroplated copper heating layer deposited on the surface of the pre-treatment transition layer by an electroplating solution; the surface of the electroplated copper heating layer is formed with a heating pattern obtained by etching with an etching solution. The electroplating solution contains the following components at the following concentrations: copper sulfate 180-200 g / L, sulfuric acid 100-120 g / L, chloride ions 40-50 ppm, and copper plating brightener 0.6-0.8 g / L; The etching solution contains the following components at the following concentrations: copper chloride 90-100 g / L, hydrochloric acid 45-50 g / L, and thiourea corrosion inhibitor 0.8-1 g / L.

2. The aluminum-based composite copper foil heating element according to claim 1, characterized in that, The pure aluminum foil substrate has a thickness of 0.05mm-0.5mm, a purity of ≥99.9%, and a surface roughness Ra≤0.2μm.

3. The aluminum-based composite copper foil heating element according to claim 1, characterized in that, The pretreatment transition layer is a copper seed layer with a thickness of 0.1-0.5 μm formed by magnetron sputtering, or a zinc transition layer and a thin copper composite layer formed by one-step wet pretreatment.

4. The aluminum-based composite copper foil heating element according to claim 1, characterized in that, The thickness of the electroplated copper heating layer is 1-8 μm.

5. The aluminum-based composite copper foil heating element according to claim 1, characterized in that, The heating element also includes an antioxidant protective film formed on the surface of the electroplated copper heating layer; The antioxidant protective film is made of an antioxidant liquid containing: 1.5-2 g / L benzotriazole and 0-0.3 g / L silane coupling agent.

6. The aluminum-based composite copper foil heating element according to claim 1, characterized in that, The heating pattern is a conductive heating pattern, and the line width accuracy of the conductive heating pattern is ±0.01mm, and the line spacing accuracy is ±0.02mm.

7. A method for preparing an aluminum-based composite copper foil heating element according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Substrate pretreatment: The pure aluminum foil substrate is pretreated to form a pretreatment transition layer on the substrate surface; The pretreatment is either magnetron sputtering pretreatment or one-step wet pretreatment. S2. Electroplated copper after treatment: The pretreated substrate is placed in the electroplating solution for electroplating to form an electroplated copper heating layer. Then it is washed with water and subjected to anti-oxidation treatment and dried to obtain electroplated copper after treatment. S3. Photolithography and etching: The electroplated copper after treatment is subjected to the first film lamination, micro-etching, photolithography dry film lamination, exposure, and development in sequence, and the etching solution is used to etch to form a heating pattern; then the second film lamination and acid washing are performed, and finally the aluminum-based composite copper foil heating sheet is die-cut to obtain the heating sheet.

8. The method for preparing the aluminum-based composite copper foil heating element according to claim 7, characterized in that, The conditions for magnetron sputtering pretreatment in step S1 are: copper as the target material, and an ultimate vacuum of 3.8 × 10⁻⁶ in the sputtering chamber. -4 Pa -4.2×10 -4 Pa, target-substrate spacing 50-70mm, sputtering temperature 140-160℃, sputtering power 150-250W, sputtering time 2-4min.

9. The method for preparing the aluminum-based composite copper foil heating element according to claim 7, characterized in that, The wet pretreatment step S1 includes the following steps: Degreasing: Treat with 50-70 g / L sodium hydroxide and 6-10 g / L surfactant at 50-70℃ for 3-8 min; Alkaline etching: Treat with 20-40 g / L sodium hydroxide at 40-60℃ for 1-3 min; Descaling: Treat with 110-130 g / L nitric acid at 20-30℃ for 30-90 seconds; Zinc precipitation: Treat with 90-110 g / L zinc sulfate and 20-30 g / L ammonium chloride at 20-30℃ for 30-60 seconds; Copper plating: Use 6-10 g / L copper sulfate and 12-18 g / L EDTA at 30-40℃ for 1-2 min, and control the pH value to 9.5-10.5; supplement each process with three-stage water washing.

10. The method for preparing the aluminum-based composite copper foil heating element according to claim 7, characterized in that, The electroplating conditions in step S2 are: temperature 20-22℃, current density 4-5A / dm³. 2 Electroplating time: 10-12 minutes; In step S3, the micro-etching is performed using a mixed solution of 50-60 g / L sulfuric acid and 12-15 g / L hydrogen peroxide at 22-25°C for 1-1.5 min; the etching conditions are a temperature of 38-40°C and a time of 5-6 min.

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