A new method for making soft state electron aluminum foil

Abstract

This invention discloses a novel method for manufacturing soft electronic aluminum foil, belonging to the field of aluminum electrolytic capacitor material manufacturing technology. The process flow of the method includes, in sequence: alloy batching, smelting, melt treatment, casting, milling, homogenization, hot rolling, cold rolling, foil rolling, intermediate annealing, foil rolling, cleaning, inert gas protected annealing, slitting, and packaging; the intermediate annealing process is omitted when manufacturing low-voltage soft electronic aluminum foil. The method eliminates the alkaline washing process after the cold rolling process, and eliminates the leveling and rewinding processes before and after the inert gas protected annealing process. Furthermore, the inert gas protected annealing process maintains a slightly positive pressure inert gas atmosphere throughout the furnace and does not involve any vacuuming operations, reducing the traditional 17-19 processes to 13-15 processes. This invention effectively shortens the manufacturing cycle of electronic aluminum foil, reduces manufacturing costs, and produces electronic aluminum foil of the same quality as traditional methods.

Description

Technical Field

[0001] This invention relates to the field of aluminum electrolytic capacitor material manufacturing technology, and specifically to a new method for manufacturing soft electronic aluminum foil. Background Technology

[0002] Electronic aluminum foil is a core material in the manufacture of aluminum electrolytic capacitors. After etching and formation processes, the electronic aluminum foil becomes electrode foil, which is used as the positive and negative electrodes of the aluminum electrolytic capacitor. The performance of the electrode foil determines the electrical performance of the aluminum electrolytic capacitor, and the performance of the electronic aluminum foil, in turn, determines the electrical performance of the electrode foil. Therefore, the quality and manufacturing level of the electronic aluminum foil directly affect the final performance of the aluminum electrolytic capacitor.

[0003] Electronic aluminum foil can be classified into soft electronic aluminum foil and hard electronic aluminum foil according to its state. Soft electronic aluminum foil is the positive electrode material for manufacturing aluminum electrolytic capacitors. Its cubic texture content is a key indicator for evaluating the quality of soft electronic aluminum foil. The higher the cubic texture content, the larger the corrosion specific surface area and the higher the specific capacitance of the electrode foil. The raw material used to manufacture soft electronic aluminum foil is usually high-purity aluminum, which is well known in the field. Its typical composition system is as follows: using high-purity aluminum with an aluminum content of ≥99.99% as raw material, the alloy composition after melting is controlled by weight percentage as follows: Fe 0.0005%~0.004%, Si 0.001%~0.004%, Cu 0.0015%~0.008%, Zn 0.0005%~0.002%, B 0.0001%~0.001%, Ga 0.0005%~0.002%, and Al content ≥99.98%.

[0004] In the existing technology, the typical manufacturing process of soft electronic aluminum foil usually includes 17-19 steps, specifically: alloy batching, melting, melt treatment, casting, milling, homogenization, hot rolling, cold rolling, alkaline washing, cold rolling, foil rolling, intermediate annealing, foil rolling, cleaning, tension leveling, slitting, vacuum annealing, rewinding, and packaging. For low-voltage soft electronic aluminum foil, the typical process does not include the intermediate annealing step, but still includes the other steps mentioned above.

[0005] Regarding the annealing process, the following technical solutions exist in the existing technology: Chinese patent CN1390961A discloses a method for annealing high-purity aluminum foil with a strong cubic texture for electrolytic capacitors. This method employs a multi-stage annealing process, creating negative atmospheric pressure by evacuating the furnace cavity in the low-temperature stage and filling the furnace cavity with inert gas in the high-temperature stage. Although this method introduces inert gas protection in the high-temperature stage, it still requires evacuation of the annealing furnace in the low-temperature stage, necessitating a vacuum evacuation system and placing high demands on the vacuum sealing of the annealing furnace. Furthermore, the annealing process requires switching between evacuation and filling states, making process control complex. In addition, this method does not propose a technical solution for overall process simplification and still requires traditional auxiliary processes such as alkaline washing, straightening, and rewinding.

[0006] Chinese patent CN03108574.1 discloses a method for annealing medium- and high-voltage electronic aluminum foil products in a vacuum furnace. This method involves annealing in a vacuum furnace, requiring a complete vacuum pumping system to maintain a high vacuum state inside the furnace during the annealing process. This method suffers from problems such as complex annealing equipment structure, high equipment investment, high maintenance costs, and long preparation time for each annealing cycle.

[0007] In summary, the existing typical processes have the following shortcomings: First, an alkaline washing process is required during cold rolling to remove residual rolling oil and oxide layer from the aluminum foil surface. After alkaline washing, multiple auxiliary processes such as neutralization, rinsing, and drying are required, making the process cumbersome. Furthermore, a large amount of alkaline waste liquid is generated, increasing the environmental protection burden and manufacturing costs.

[0008] Secondly, both the traditional vacuum annealing process and the mixed annealing process of low-temperature evacuation and high-temperature inert gas filling described in CN1390961A require vacuuming of the vacuum annealing furnace, which takes a long time for a single annealing process; and it places high demands on vacuum equipment and vacuum sealing performance, resulting in large equipment investment, high maintenance costs, and high energy consumption.

[0009] Third, a straightening process is required before traditional vacuum annealing to ensure the flatness of the aluminum foil before it enters the annealing process; after vacuum annealing, the aluminum foil is loosely wound, so a rewinding process is required to rewind and reshape the aluminum foil, which adds two auxiliary processes and equipment investment.

[0010] Fourth, existing typical processes are long, involve many steps, have long manufacturing cycles, and are costly, which is not conducive to the short-cycle, low-cost production of electronic aluminum foil.

[0011] Therefore, developing a new method for manufacturing flexible electronic aluminum foil with fewer processes, shorter cycle time, lower cost, and guaranteed product quality has significant industrial application value. Summary of the Invention

[0012] The purpose of this invention is to overcome the shortcomings of existing technologies in the manufacturing of soft electronic aluminum foil, such as long process flow, numerous steps, long manufacturing cycle, high manufacturing cost, and the need for vacuum operation in the annealing process, and to provide a new method for manufacturing soft electronic aluminum foil. The core innovation of this invention lies in: through the synergistic optimization of cold rolling oil formula, annealing atmosphere, and annealing process, the three auxiliary processes of alkaline washing, tension leveling, and rewinding in the traditional process can be eliminated simultaneously without any vacuum operation, reducing the process flow from 17-19 steps to 13-15 steps, and achieving systematic simplification of the process flow while ensuring product quality.

[0013] The objective of this invention is achieved through the following technical solution: A novel method for manufacturing soft electronic aluminum foil, comprising the following 15 steps in sequence: alloy batching, smelting, melt treatment, casting, milling, homogenization, hot rolling, cold rolling, foil rolling, intermediate annealing, foil rolling, cleaning, inert gas protected annealing, slitting, and packaging. The method omits an alkaline washing step after the cold rolling step, a leveling step before the inert gas protected annealing step, and a rewinding step after the inert gas protected annealing step. The inert gas protected annealing meets the following conditions: after the annealing furnace is loaded and inert gas is introduced to replace the air, the furnace is maintained at a slightly positive pressure inert gas atmosphere throughout the entire annealing process, from the heating stage to the cooling and removal from the furnace, without any vacuuming operation.

[0014] Furthermore, when manufacturing low-voltage soft electronic aluminum foil, the process flow of the method does not include an intermediate annealing process. The process flow consists of the following 13 steps in sequence: alloy batching, smelting, melt treatment, casting, milling, homogenization, hot rolling, cold rolling, foil rolling, cleaning, inert gas protected finished product annealing, slitting, and packaging.

[0015] Furthermore, the inert gas used in the inert gas protection annealing of the finished product is nitrogen, argon, or a mixture of both; the relative pressure of the slightly positive pressure atmosphere of the inert gas is maintained at 50Pa-500Pa; the inert gas is continuously introduced into the furnace and discharged outside the furnace during the annealing process, and the gas replacement frequency in the furnace is 2 times and 0 times per furnace.

[0016] Furthermore, the purity of the inert gas is not less than 99.99%; the oxygen content in the annealing furnace is maintained below 50 ppm throughout the annealing process.

[0017] Furthermore, the process parameters for the inert gas protected annealing of the finished product are: annealing temperature 450℃~580℃, holding time 4h~20h, heating rate 20℃ / h~80℃ / h, and cooling in the furnace to below 130℃ before air cooling.

[0018] Furthermore, the alloy composition uses high-purity aluminum with an aluminum content of ≥99.99% as raw material; after smelting and melt treatment, the resulting aluminum alloy contains, by weight percentage: Fe 0.0005%~0.004%, Si 0.001%~0.004%, Cu 0.0015%~0.008%, Zn 0.0005%~0.002%, B 0.0001%~0.001%, Ga 0.0005%~0.002%, with the remainder being Al and unavoidable impurities, and the Al content being ≥99.98%.

[0019] Furthermore, the cold rolling process and the foil rolling process use low-viscosity rolling oil with a kinematic viscosity of 2.2 mm² / s-3.2 mm² / s (40℃), and the flash point of the cold rolling and foil rolling oil is not lower than 90℃; the residual oil content on the surface of the aluminum foil after cold rolling and foil rolling is controlled to be below 30 mg / m².

[0020] Furthermore, the intermediate annealing temperature is 200℃~260℃, and the holding time is 3h~10h.

[0021] Furthermore, the thickness of the aluminum foil after rolling is 0.08-0.16 mm.

[0022] Furthermore, the cleaning process involves high-pressure spraying and roller brushing of cleaning oil on the surface of the aluminum foil to remove residual rolling oil and aluminum powder from the foil rolling process, followed by hot air drying until there is no residual oil on the surface of the aluminum foil.

[0023] The advantages of this invention over the prior art are as follows: First, by optimizing the cold rolling and foil rolling oil formulations, applying an inert gas protective annealing atmosphere, and coordinating the design of the annealing process, this invention achieves the simultaneous elimination of three auxiliary processes in the traditional process—alkali washing, straightening, and rewinding—without performing any vacuuming operations. This reduces the process flow from 17-19 processes to 13-15 processes, a reduction of approximately 22% to 26%, and shortens the manufacturing cycle by approximately 20% to 25%.

[0024] Secondly, compared with the mixed annealing method of low-temperature evacuation and high-temperature inert gas filling disclosed in CN1390961A, the inert gas protected finished product annealing of the present invention does not require vacuuming during the entire annealing process. It only requires an inert gas supply and exhaust system, without the need for a vacuum evacuation system, which greatly simplifies the structure of the annealing equipment and reduces the requirements for the vacuum sealing of the furnace body. At the same time, the process control of the annealing process is simpler, and there is no need to switch between the two states of evacuation and filling.

[0025] Third, compared with the traditional vacuum annealing method, the inert gas protected finished product annealing of the present invention can reduce the investment in annealing equipment by about 60% to 70%, reduce energy consumption by about 15% to 25%, and shorten the total time of a single annealing by about 2 hours to 6 hours.

[0026] Fourth, this invention eliminates the alkaline washing process, avoids the generation of alkaline waste liquid, reduces environmental treatment costs, and conforms to the development direction of green manufacturing.

[0027] Fifth, the present invention eliminates the straightening and rewinding processes, further reducing equipment investment and process flow time.

[0028] Sixth, the four process improvements described in this invention—eliminating alkaline washing, employing inert gas protection annealing without vacuum throughout, eliminating tension leveling, and eliminating rewinding—are not simply isolated steps superimposed, but rather an interconnected, mutually supportive, and synergistic organic whole. The optimization of the rolling oil formula makes eliminating alkaline washing possible; the inert gas protection annealing throughout (distinct from traditional vacuum annealing and existing mixed annealing involving low-temperature extraction and high-temperature inflation) not only replaces vacuum annealing itself but also ensures that the elimination of alkaline washing, tension leveling, and rewinding processes does not compromise product quality; furthermore, eliminating alkaline washing, tension leveling, and rewinding further amplifies the advantages of cycle time reduction and cost reduction brought about by the inert gas protection annealing process. These four process improvements constitute an inseparable, holistic technical solution with significant overall synergistic effects.

[0029] Seventh, testing shows that the soft electronic aluminum foil prepared by the method described in this invention has essentially the same key indicators as the electronic aluminum foil prepared by existing typical methods in terms of cubic texture content, tensile strength, elongation and surface quality, and fully meets the requirements for use as positive electrode material of aluminum electrolytic capacitors. Detailed Implementation

[0030] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments.

[0031] Example 1 (Manufacturing of medium- and high-voltage soft electronic aluminum foil) This embodiment provides a method for manufacturing medium- and high-voltage soft electronic aluminum foil, the specific steps of which are as follows: Step 1, Alloy Batching: High-purity aluminum with an aluminum content of ≥99.99% is used as raw material. The raw materials are batched according to weight percentage and the alloy composition after smelting is controlled as follows: Fe 0.0025%, Si 0.0020%, Cu 0.0050%, Zn 0.0010%, B 0.0005%, Ga 0.0010%, with the remainder being Al and unavoidable impurities, and the Al content is ≥99.98%.

[0032] Step 2, Smelting: The ingredients obtained in Step 1 are put into a smelting furnace and smelted at 730℃~760℃, and kept at the temperature until the raw materials are completely melted and homogenized.

[0033] Step 3, Melt treatment: The melt obtained in step 2 is refined, degassed, and slag removed. High-purity argon gas is used to blow the melt for refining, and the hydrogen content of the melt is controlled to be less than or equal to 0.12 mL / 100 g Al.

[0034] Step 4, Casting: The melt processed in Step 3 is cast into aluminum alloy ingots using a semi-continuous casting method.

[0035] Step 5, Milling: The surface of the ingot obtained in Step 4 is machined and milled to remove the oxide scale and segregation layer on the casting surface. The single-sided milling amount is 8mm-15mm.

[0036] Step 6, homogenization: The milled ingot obtained in step 5 is subjected to homogenization heat treatment at a temperature of 580℃-610℃ for a holding time of 10h-24h.

[0037] Step 7, hot rolling: The ingot after homogenization in step 6 is hot rolled into a hot-rolled coil with a thickness of 6mm-8mm.

[0038] Step 8, cold rolling: The hot-rolled coil obtained in step 7 is cold-rolled to a thickness of 0.2mm-0.6mm; this step uses low-viscosity cold rolling oil with a kinematic viscosity of 2.8mm² / s (40℃) and a flash point of 100℃, and the residual oil content on the aluminum foil surface after cold rolling is controlled to be below 20mg / m²; no alkaline washing is performed after this step.

[0039] Step 9, Foil Rolling (Rough Foil Rolling): The cold-rolled coil obtained in Step 8 is further rolled into a rough foil with a thickness of 0.10 mm to 0.20 mm.

[0040] Step 10, intermediate annealing: carried out under inert gas protection, annealing temperature 230℃, holding time 5h, to adjust the microstructure of aluminum foil.

[0041] Step 11, Foil Rolling (Refine Foil Rolling): The aluminum foil after intermediate annealing in Step 10 is further rolled to a finished thickness of 0.08-0.16 mm.

[0042] Step 12, Cleaning: The aluminum foil surface obtained in Step 11 is cleaned by high-pressure spraying and roller brushing with cleaning oil to remove the rolling oil and aluminum powder remaining during the foil rolling process, and then dried with hot air until there is no residual oil on the aluminum foil surface.

[0043] Step 13, Inert Gas Protected Annealing: The aluminum foil rolls cleaned in Step 12 are placed into the annealing furnace. After closing the furnace door, high-purity nitrogen (99.99% purity) is introduced into the furnace to replace the air inside for at least 30 minutes. After replacement, the temperature is raised. Nitrogen is introduced into the furnace before the material temperature reaches 310°C. When the material temperature reaches 310°C, the gas in the furnace is replaced with argon and maintained until the end of the holding period and the early stage of cooling. The process continues until the material temperature drops to... When the temperature is below 310℃, replace the gas in the furnace with nitrogen; maintain a slight positive pressure of 200Pa for the relative pressure of the gas in the furnace, and control the oxygen content in the furnace to below 30ppm. During the entire annealing process from heating to cooling and removal from the furnace, continuously introduce inert gas and allow it to be naturally discharged outside the furnace without performing any vacuuming operations. Heat the furnace to the annealing temperature of 540℃ at a rate of 20℃ / h and hold for 12 hours. After holding, cool the furnace to below 130℃ and then remove the furnace for air cooling.

[0044] Step 14, Slitting: The annealed aluminum foil roll obtained in Step 13 is directly slit. No straightening is performed before this step, and no rewinding is performed after this step.

[0045] Step 15, Packaging: Vacuum or moisture-proof packaging of the finished aluminum foil cut in Step 14 according to specifications.

[0046] Example 2 (Manufacturing of low-voltage soft electronic aluminum foil) This embodiment provides a method for manufacturing low-pressure soft electronic aluminum foil. The process flow of the method includes the following 13 steps in sequence: alloy batching, smelting, melt treatment, casting, milling, homogenization, hot rolling, cold rolling, foil rolling, cleaning, inert gas protected annealing, slitting, and packaging.

[0047] The process parameters for each step in this embodiment are basically the same as those in Embodiment 1. The difference is that: no intermediate annealing process is set in this embodiment; the thickness of the aluminum foil after foil rolling is controlled at 80μm; the annealing temperature of the finished product under inert gas protection is 300℃ and the holding time is 10h. Other annealing parameters are the same as those in Embodiment 1.

[0048] Comparative example (manufacturing flexible electronic aluminum foil using existing typical processes) This comparative example adopts a typical 19-step process flow: alloy batching, smelting, melt treatment, casting, milling, homogenization, hot rolling, cold rolling, alkaline washing, cold rolling, foil rolling, intermediate annealing, foil rolling, cleaning, tension leveling, slitting, vacuum annealing, rewinding, and packaging. The alloy composition, smelting temperature, rolling thicknesses, intermediate annealing temperature, and other parameters of this comparative example are the same as those in Example 1; the vacuum annealing process is as follows: vacuum is drawn to below 5×10⁻³ Pa, the temperature is increased to 540℃ at a rate of 10-40℃ / h, held at that temperature for 12h, and then cooled in the furnace.

[0049] Synergistic effect comparison test To verify the synergistic effect among the four process improvements described in this invention, the following comparative test groups (test group 1-A to test group 1-D) were designed. The finished aluminum foils of each test group were tested using the same detection method to determine key indicators such as cubic texture content, tensile strength, elongation, surface residual oil content, and electrode foil specific capacity.

[0050] Experimental Group 1-A (This invention, corresponding to Example 1): Low viscosity rolling oil was used, alkaline washing was eliminated, inert gas protection annealing was carried out without vacuum throughout the process, and tension leveling and rewinding were eliminated.

[0051] Experimental Group 1-B (Control 1, only alkaline washing is omitted, vacuum annealing is still used): low viscosity rolling oil is used, alkaline washing is omitted, vacuum annealing (5×10⁻³Pa) is still used, and tension leveling and rewinding processes are retained.

[0052] Experimental Group 1-C (Control 2, retaining alkaline washing, using inert gas protection annealing): ordinary high viscosity rolling oil was used, alkaline washing was retained, and inert gas protection annealing was used throughout the process without vacuuming, and tension leveling and rewinding were eliminated.

[0053] Experimental group 1-D (control 3, inert gas annealing but retaining tension leveling and rewinding): low viscosity rolling oil was used, alkaline washing was eliminated, inert gas protection annealing was carried out without vacuum throughout the process, and tension leveling and rewinding were retained.

[0054] The test results for each experimental group are shown in Table 1 below.

[0055] Table 1 Results of the comparative experiment on synergistic effects

[0056] The following important conclusions can be drawn from the data in Table 1: Conclusion 1: In experimental group 1-B (alkaline washing only omitted, vacuum annealing still used), the cubic texture content significantly decreased to 92.1%, the surface residual oil content was as high as 32 mg / m² and contained carbides, and the electrode foil specific capacitance also decreased significantly to 0.75 μF / cm². This is because during traditional vacuum annealing, the residual oil on the aluminum foil surface undergoes thermal decomposition to form carbides during the heating and vacuuming process. Without deep degreasing by alkaline washing, vacuum annealing cannot handle the small amount of residual oil left by low-viscosity water-washed cold rolling oil. Therefore, it is not feasible to simply eliminate alkaline washing without changing the annealing method; eliminating alkaline washing must be implemented in conjunction with inert gas protected annealing to ensure product quality.

[0057] Conclusion 2: The indicators of experimental group 1-C (with alkaline washing retained and inert gas annealing adopted) are basically the same as those of experimental group 1-A. However, retaining the alkaline washing process means retaining the environmental burden of alkaline waste liquid and the corresponding investment in auxiliary processes, which fails to reflect the core advantage of the simplified process of the present invention.

[0058] Conclusion 3: The indicators of test group 1-D (inert gas annealing but with tension straightening and rewinding) are basically the same as those of test group 1-A. This indicates that, under the premise of using the non-vacuum inert gas protection annealing method of the present invention, the shape and winding neatness of the aluminum foil roll can be formed naturally during the annealing process without the need for additional tension straightening and rewinding processes.

[0059] The results of the three comparative tests above show that the four improvements of this invention—eliminating alkaline washing, inert gas protective annealing (without vacuum throughout the process), eliminating tension straightening, and eliminating rewinding—have a significant synergistic effect. Among them, inert gas protective annealing is the core prerequisite for the other three process reductions to be effective. Implementing any one improvement alone cannot achieve the overall technical effect of this invention. All four improvements must be implemented simultaneously to achieve a systematic simplification of the process flow while ensuring that the product quality remains substantially the same.

[0060] Comparison of the present invention with existing technologies The performance of Example 1 was compared with that of the comparative example (existing typical process), and the results are shown in Table 2.

[0061] Table 2 Performance Comparison Results of Example 1 and Comparative Example

[0062] As can be seen from the data in Table 2, the key indicators of the soft electronic aluminum foil prepared by the method of the present invention, such as cubic texture content, tensile strength, elongation and surface quality, are substantially the same as those of the electronic aluminum foil prepared by the existing typical methods. Under the premise of substantially the same product quality, the process flow of the method of the present invention is shortened by about 21%, the manufacturing cycle is shortened by about 20%, and no alkaline waste liquid is generated, and the overall manufacturing cost is reduced by about 15%-20%.

[0063] Substantial differences between this invention and prior art document CN1390961A The prior art document CN1390961A employs a multi-stage mixed annealing process involving low-temperature evacuation and high-temperature inert gas filling. This process requires evacuating the furnace to negative atmospheric pressure during the low-temperature stage. In contrast, the inert gas-protected annealing method described in this invention maintains a slightly positive inert gas atmosphere throughout the entire annealing process, from the initial charging and air replacement with inert gas, until cooling and unloading. No vacuuming is performed during the entire process. The essential differences between the two are as follows: Difference 1: Equipment requirements differ. CN1390961A still requires a vacuum extraction system (for low-temperature extraction) and an inert gas supply system (for high-temperature filling), placing high demands on the vacuum sealing of the furnace body. This invention only requires an inert gas supply and exhaust system, eliminating the need for a vacuum extraction system. This reduces the requirements for furnace sealing, resulting in significantly lower equipment investment and maintenance costs compared to CN1390961A.

[0064] Difference 2: Different process control. The annealing process of CN1390961A requires switching between two states of gas extraction and gas filling, which makes the process control complex; the present invention maintains a single inert gas micro-positive pressure state throughout the entire process from air replacement to air cooling after exiting the furnace, which makes the process control simple and reliable.

[0065] Difference 3: The overall process is different. CN1390961A only proposes a technical solution for the finished product annealing process, without addressing the overall simplification of the process flow. It still requires the implementation of traditional auxiliary processes such as alkaline washing, tension straightening, and rewinding. This invention, on the other hand, proposes an overall technical solution that includes four process improvements: eliminating alkaline washing, using inert gas protection annealing without vacuum throughout the process, eliminating tension straightening, and eliminating rewinding. This achieves a systematic simplification of the process flow from 17-19 steps to 13-15 steps.

[0066] In summary, this invention, through systematic optimization of the typical process of existing flexible electronic aluminum foil, reduces the process flow from 17-19 steps to 13-15 steps while ensuring product quality. This simplifies the process, shortens the manufacturing cycle, and reduces manufacturing costs, demonstrating significant industrial application value.

[0067] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A new method of soft state electron aluminum foil manufacturing characterized by: The process flow of the method includes the following 15 steps in sequence: alloy batching, smelting, melt treatment, casting, milling, homogenization, hot rolling, cold rolling, foil rolling, intermediate annealing, foil rolling, cleaning, inert gas protected finished product annealing, slitting, and packaging. The method does not include an alkaline washing step after the cold rolling step, a tension leveling step before the inert gas protected finished product annealing step, or a rewinding step after the inert gas protected finished product annealing step. The inert gas protected finished product annealing meets the following conditions: after the annealing furnace is loaded and inert gas is introduced to replace the air, the furnace is kept in a slightly positive pressure atmosphere of inert gas from the heating stage to the cooling and unloading process, and no vacuuming operation is performed throughout the process.

2. The new method of making soft-state electronic aluminum foil according to claim 1, characterized by: When manufacturing low-voltage soft electronic aluminum foil, the process flow of the method does not include an intermediate annealing process. The process flow of the method consists of the following 13 steps in sequence: alloy batching, smelting, melt treatment, casting, milling, homogenization, hot rolling, cold rolling, foil rolling, cleaning, inert gas protected finished product annealing, slitting, and packaging.

3. The new method of making soft-state electronic aluminum foil according to claim 1 or 2, characterized in that: The inert gas used in the inert gas protection annealing of the finished product is nitrogen, argon, or a mixture of both; the relative pressure of the slightly positive pressure atmosphere of the inert gas is maintained at 50Pa~500Pa; the inert gas is continuously introduced into the furnace and discharged outside the furnace during the annealing process, and the number of gas replacements in the furnace is 2 times and 0 times.

4. The new method of making soft-state electronic aluminum foil according to claim 3, characterized in that: The purity of the inert gas is not less than 99.99%; the oxygen content in the annealing furnace is maintained below 50 ppm throughout the annealing process.

5. The new method of making soft-state electronic aluminum foil according to claim 1 or 2, characterized by: The process parameters for the inert gas protected annealing of the finished product are as follows: annealing temperature 450℃~580℃, holding time 4h~20h, heating rate 10℃ / h~40℃ / h, and cooling in the furnace to below 130℃ before air cooling.

6. The new method of making soft-state electronic aluminum foil according to claim 1 or 2, characterized by: The alloy composition uses high-purity aluminum with an aluminum content of ≥99.99% as raw material; after smelting and melt treatment, the resulting aluminum alloy contains, by weight percentage: Fe 0.0005%~0.004%, Si 0.001%~0.004%, Cu 0.0015%~0.008%, Zn 0.0005%~0.002%, B 0.0001%~0.001%, Ga 0.0005%~0.002%, with the remainder being Al and unavoidable impurities, and the Al content being ≥99.98%.

7. The new method of making soft-state electronic aluminum foil according to claim 1 or 2, characterized by: The cold rolling and foil rolling processes use low-viscosity rolling oil with a kinematic viscosity of 2.2 mm² / s-3.2 mm² / s (40℃), and the flash point of the rolling oil is not lower than 90℃; the residual oil content on the aluminum foil surface after cold rolling and foil rolling is controlled to be below 30 mg / m².

8. The new method of making soft-state electronic aluminum foil according to claim 1, characterized by: The intermediate annealing temperature is 200℃~260℃, and the holding time is 3h~10h.

9. The new method of making soft-state electronic aluminum foil according to claim 1 or 2, characterized by: The thickness of the aluminum foil after rolling is 60μm~160μm.

10. The new method of making soft-state electronic aluminum foil according to claim 1 or 2, characterized by: The cleaning process involves high-pressure spraying and roller brushing of cleaning oil on the surface of the aluminum foil to remove residual rolling oil and aluminum powder from the foil rolling process, followed by hot air drying until there is no residual oil on the surface of the aluminum foil.

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