Formed foil and preparation method thereof

Abstract

The invention relates to the technical field of electrode foils, and provides a formed foil and a preparation method thereof. The preparation method of the formed foil comprises the following steps: sequentially performing formation treatment, first infrared heating treatment and post-treatment on a corrosion aluminum foil to prepare the formed foil. Infrared heating is adopted in the process of preparing the formed foil, uniform heating of the surface of the aluminum foil can be achieved, the crystal structure and the chemical stability of an oxidation film can be optimized, the compact and uniform oxidation film can be formed easily, defects of the oxidation film are reduced, the bending index of the formed foil is improved, and the transverse withstand voltage difference value and the specific capacitance dispersion difference are reduced. Besides, the infrared heating technology has the advantages of high heating efficiency, high heating speed, uniform temperature, good controllability, low energy consumption and the like, the heat treatment time of the formed foil can be remarkably shortened, the production efficiency is improved, and the cost is reduced.

Description

Technical Field

[0001] This application relates to the field of electrode foil technology, and in particular to a chemically formed foil and its preparation method. Background Technology

[0002] Formed foil is a crucial component of aluminum electrolytic capacitors, and its quality directly impacts the capacitor's performance and lifespan. The production process involves forming and heating the aluminum foil to create an oxide film with specific electrical properties on its surface. However, currently produced formed foils often exhibit poor oxide film uniformity, leading to significant deviations in lateral withstand voltage (inconsistent withstand voltage at different locations) and causing leakage current to exceed standard limits. Therefore, providing a formed foil with a uniform oxide film is a pressing technical challenge that needs to be addressed. Summary of the Invention

[0003] Therefore, it is necessary to provide an oxide foil and its preparation method to solve the problem of poor oxide film uniformity in aluminum foil.

[0004] In a first aspect, this application provides a method for preparing a chemically formed foil, the method comprising: sequentially performing a chemical formation treatment, a first infrared heating treatment, and a post-treatment on an etched aluminum foil to prepare the chemically formed foil.

[0005] In some embodiments, the temperature of the first infrared heating treatment is 400°C to 450°C, the time is 30s to 70s, and the wavelength of the infrared radiation is 3.0μm to 6.5μm.

[0006] In some embodiments, the formation process includes a first-stage formation operation, a second infrared heating treatment, and a second-stage formation operation performed sequentially.

[0007] In some embodiments, the temperature of the second infrared heating treatment is 300°C to 350°C, the time is 50s to 70s, and the wavelength of the infrared radiation is 3.5μm to 7.0μm.

[0008] In some implementations, the first-level transformation operation includes a first-level sub-transformation operation, a second-level sub-transformation operation, a third-level sub-transformation operation, and a fourth-level sub-transformation operation performed sequentially.

[0009] And / or, the second-level transformation operation includes the fifth-level sub-transformation operation and the sixth-level sub-transformation operation performed sequentially.

[0010] In some embodiments, the formation process also satisfies at least one of the following conditions:

[0011] (1) The formation solution for the primary electron formation operation includes 1.2 g / L to 2.5 g / L ammonium dihydrogen phosphate, 0.5 g / L to 1.1 g / L citric acid, and 0.5 g / L to 1.1 g / L triammonium citrate; the current density for the primary electron formation operation is 60 mA / cm². 2 ~80mA / cm 2 The voltage is 140V~200V, the time is 8min~10min, and the temperature is 85℃~90℃;

[0012] (2) The formation solution for the secondary electron formation operation includes 0.3 g / L~0.7 g / L ammonium dihydrogen phosphate, 0.5 g / L~1.1 g / L citric acid, and 0.5 g / L~1.1 g / L triammonium citrate; the current density for the secondary electron formation operation is 60 mA / cm². 2~ 80mA / cm 2 The voltage is 310V~340V, the time is 7min~11min, and the processing temperature is 85℃~90℃;

[0013] (3) The tertiary formation solution includes 0.5 g / L~1.0 g / L citric acid and 0.3 g / L~0.8 g / L triammonium citrate; the current density of the tertiary formation operation is 60 mA / cm². 2 ~80mA / cm 2 The voltage is 470V~500V, the time is 8min~10min, and the temperature is 85℃~90℃;

[0014] (4) The quaternary formation solution includes 0.50 g / L to 0.70 g / L ammonium azelate and 0.80 g / L to 1.0 g / L azelic acid; the current density of the quaternary formation operation is 60 mA / cm². 2 ~80mA / cm 2 The voltage is 580V~600V, the time is 8min~10min, and the temperature is 85℃~90℃;

[0015] (5) The quintet formation solution includes 0.2 g / L to 0.30 g / L ammonium azelate and 0.7 g / L to 1.0 g / L azelic acid; the current density of the quintet formation operation is 60 mA / cm². 2 ~80mA / cm 2 The voltage is 630V~650V, the time is 8min~10min, and the temperature is 85℃~90℃;

[0016] (6) The formation solution for the hexa-ion formation operation includes 0.40 g / L to 0.55 g / L ammonium pentaborate and 45 g / L to 55 g / L boric acid; the current density for the hexa-ion formation operation is 60 mA / cm². 2 ~80mA / cm 2The voltage is 650V~670V, the time is 4min~6min, and the temperature is 85℃~90℃.

[0017] In some embodiments, the post-processing includes: a first chemical treatment, a first remediation formation, a third infrared heating treatment, a second chemical treatment, a second remediation formation, and a third chemical treatment performed sequentially.

[0018] In some embodiments, the temperature of the third infrared heating treatment is 450℃~550℃, the time is 30s~70s, and the wavelength of the infrared radiation is 2.5μm~6.5μm.

[0019] In some implementations, the post-processing also satisfies at least one of the following conditions:

[0020] (1) The treatment solution for the first chemical treatment includes 60 g / L to 70 g / L phosphoric acid; the time for the first chemical treatment is 4 min to 5 min, and the temperature is 65℃ to 75℃;

[0021] (2) The remediation solution used in the first remediation formation includes 0.40 g / L to 0.60 g / L ammonium pentaborate and 45 g / L to 55 g / L boric acid; the current density of the first remediation formation is 30 mA / cm². 2 ~40mA / cm 2 The voltage is 650V~670V, the time is 2.5min~3.5min, and the temperature is 85℃~90℃;

[0022] (3) The treatment solution for the second chemical treatment includes 6.0 g / L to 10 g / L phosphoric acid; the second chemical treatment time is 4 min to 7 min, and the temperature is 55℃ to 75℃;

[0023] (4) The remediation solution used in the second remediation formation includes 0.40 g / L to 0.60 g / L ammonium pentaborate and 45 g / L to 55 g / L boric acid; the current density of the second remediation formation is 30 mA / cm². 2 ~40mA / cm 2 The voltage is 640V~660V, the time is 2.5min~3.5min, and the temperature is 85℃~90℃;

[0024] (5) The treatment solution for the third chemical treatment includes 3.0 g / L to 8.0 g / L ammonium dihydrogen phosphate; the time for the third chemical treatment is 3 min to 6 min, and the temperature is 20℃ to 75℃.

[0025] Secondly, this application provides a chemically formed foil, which is prepared using the chemically formed foil preparation method described in the first aspect.

[0026] Compared with traditional technologies, this application has at least the following beneficial effects:

[0027] This application employs infrared heating during the preparation of the formed foil, which enables uniform heating of the foil surface. This optimizes the crystalline structure and chemical stability of the oxide film, facilitating the formation of a dense and uniform oxide film, reducing oxide film defects, improving the bending performance of the formed foil, and decreasing the transverse withstand voltage difference and specific capacitance dispersion. Furthermore, infrared heating technology offers advantages such as high heating efficiency, rapid heating speed, uniform temperature, good controllability, and low energy consumption, significantly shortening the heat treatment time of the formed foil, improving production efficiency, and reducing costs. Attached Figure Description

[0028] Figure 1 This is a SEM image of the chemically formed foil prepared in Example 1 of this application at a magnification of 10,000.

[0029] Figure 2 This is a SEM image of the electroformed foil prepared in Example 1 of this application at a magnification of 1000x.

[0030] Figure 3 The image shown is a SEM image of the electroformed foil prepared in Comparative Example 1 of this application at a magnification of 10,000.

[0031] Figure 4 This is a SEM image of the chemically formed foil prepared in Comparative Example 1 of this application at a magnification of 1000x. Detailed Implementation

[0032] The present application will be further described in detail below with reference to the embodiments and examples. These embodiments and examples are only for illustrating the present application and are not intended to limit the scope of the present application. The purpose of providing these embodiments and examples is to make the disclosure of the present application more thorough and comprehensive. It should also be understood that the present application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various modifications or alterations without departing from the spirit of the present application, and the equivalent forms obtained also fall within the protection scope of the present application. In addition, numerous specific details are set forth in the following description to provide a fuller understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0034] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0035] In this application, the terms "first aspect," "second aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first aspect," "second aspect," etc., serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0036] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0037] In this application, when numerical intervals (i.e., numerical ranges) are mentioned, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0038] Traditional techniques employ resistance wire heating or hot air circulation heating for aluminum foil heat treatment. However, these methods have significant drawbacks. Firstly, the heating speed is slow, leading to longer production cycles and reduced efficiency. Secondly, the uneven temperature distribution within the oven causes uneven heating of the aluminum foil surface. Some areas may overheat, damaging the microstructure and affecting the quality of the oxide film formation; while other areas may underheat, resulting in insufficient heat treatment. This leads to significant deviations in the transverse withstand voltage of the formed foil and can cause leakage current to exceed standard limits. Furthermore, precise temperature and time control within the oven is difficult to achieve.

[0039] The first aspect of this application provides a method for preparing a chemically formed foil, the method comprising: sequentially performing a chemically formed treatment, a first infrared heating treatment, and a post-treatment on an etched aluminum foil to prepare the chemically formed foil.

[0040] This application employs infrared heating during the preparation of the formed foil, which enables uniform heating of the foil surface. This optimizes the crystalline structure and chemical stability of the oxide film, facilitating the formation of a dense and uniform oxide film, reducing oxide film defects, improving the bending performance of the formed foil, and decreasing the transverse withstand voltage difference and specific capacitance dispersion. Furthermore, infrared heating technology offers advantages such as high heating efficiency, rapid heating speed, uniform temperature, good controllability, and low energy consumption, significantly shortening the heat treatment time of the formed foil, improving production efficiency, and reducing costs.

[0041] This application employs a first infrared heating treatment, where infrared rays directly act on the surface of the aluminum foil, causing the surface to heat up rapidly. Utilizing the high efficiency and uniformity of infrared heating, the oxide film formed on the aluminum foil surface is heat-treated. Furthermore, infrared heating induces physical and chemical changes in the oxide film on the aluminum foil surface, promoting its densification and crystallization, improving its pressure resistance, insulation performance, and stability, while simultaneously enhancing the adhesion between the oxide film and the aluminum foil substrate, and reducing defects and cracks in the oxide film.

[0042] In some embodiments, before performing the formation treatment on the etched aluminum foil, the preparation method further includes: placing the etched aluminum foil in water for heating treatment. Optionally, the heating temperature of the water is 90℃~100℃, the time is 5min~15min, and the resistivity of the water is not less than 0.5MΩ·cm. Heating the etched aluminum foil in water can remove residual corrosion products, impurities, and some organic pollutants from the aluminum foil surface, while activating the aluminum foil surface, increasing its surface activity, which is beneficial to the subsequent formation reaction and ensures the quality of the oxide film formation.

[0043] In some embodiments, the temperature of the first infrared heating treatment is 400°C to 450°C, for example, 400°C, 410°C, 420°C, 430°C, 440°C, or 450°C. The time is 30s to 70s, for example, 30s, 35s, 40s, 45s, 50s, 60s, 65s, or 70s. The wavelength of the infrared radiation is 3.0μm to 6.5μm, for example, 3.0μm, 3.5μm, 4.0μm, 4.5μm, 5.0μm, 5.5μm, 6.0μm, or 6.5μm. The first infrared heating treatment performed as described above in this application can further improve the density and uniformity of the oxide film.

[0044] It should be noted that the heating temperature can be controlled by adjusting the power of the infrared heating treatment and the distance between the infrared heat source and the aluminum foil being etched. For example, the power of the infrared heating can be 5kW to 12kW, and the distance can be 80mm to 120mm.

[0045] It is understood that the formation process in this application can be adjusted according to actual formation needs, for example, a multi-step formation process can be adopted.

[0046] In some embodiments, the formation process includes a first-stage formation operation and a second-stage formation operation performed sequentially. Optionally, the formation process further includes subjecting the etched aluminum foil after the first-stage formation operation to a second infrared heating treatment, and then subjecting the etched aluminum foil after the second infrared heating treatment to a second-stage formation operation. This application adds a second infrared heating treatment to the formation process, where infrared rays directly act on the aluminum foil surface, causing the surface temperature to rise rapidly. Utilizing the high efficiency and uniformity of infrared heating, the oxide film on the aluminum foil surface is heat-treated. This process helps eliminate internal stress in the oxide film, improves the crystal structure of the oxide film, enhances the density and stability of the oxide film, and creates favorable conditions for subsequent formation.

[0047] The second infrared heating treatment is performed at a temperature of 300℃ to 350℃, for example, 300℃, 310℃, 320℃, 330℃, 340℃, or 350℃. The duration is 50s to 70s, for example, 50s, 55s, 60s, 65s, or 70s. The wavelength of the infrared radiation is 3.5μm to 7.0μm, for example, 3.5μm, 4.0μm, 4.5μm, 5.0μm, 5.5μm, 6.0μm, 6.5μm, or 7.0μm. This second infrared heating treatment, performed as described above, can further improve the density and uniformity of the oxide film.

[0048] In some embodiments, the first-level formation operation includes sequentially performed first-level sub-formation operations, second-level sub-formation operations, third-level sub-formation operations, and fourth-level sub-formation operations. The second-level formation operation includes sequentially performed fifth-level sub-formation operations and sixth-level sub-formation operations. For example, the formation process includes: sequentially performing first-level sub-formation operations, second-level sub-formation operations, third-level sub-formation operations, fourth-level sub-formation operations, second infrared heating treatment, fifth-level sub-formation operations, and sixth-level sub-formation operations.

[0049] Understandably, the forming solution and forming parameters in the forming process can be adjusted according to actual forming needs. For example, under the action of direct current, when aluminum foil is placed in a forming solution, an electrochemical reaction occurs on the surface of the aluminum foil. Aluminum atoms lose electrons to form aluminum ions, which combine with oxygen ions in the solution to initially form an aluminum oxide film on the surface of the aluminum foil. The forming solution may include boric acid and its salts, phosphoric acid and its salts, citric acid and its salts, etc.

[0050] In some embodiments, the forming solution for the primary electron formation operation includes 1.2 g / L to 2.5 g / L ammonium dihydrogen phosphate, 0.5 g / L to 1.1 g / L citric acid, and 0.5 g / L to 1.1 g / L triammonium citrate; the current density for the primary electron formation operation is 60 mA / cm². 2 ~80mA / cm 2 The voltage is 140V~200V, the time is 8min~10min, and the temperature is 85℃~90℃.

[0051] The formation solution for the secondary electron formation operation includes 0.3 g / L~0.7 g / L ammonium dihydrogen phosphate, 0.5 g / L~1.1 g / L citric acid, and 0.5 g / L~1.1 g / L triammonium citrate; the current density for the secondary electron formation operation is 60 mA / cm². 2~ 80mA / cm 2 The voltage is 310V~340V, the time is 7min~11min, and the processing temperature is 85℃~90℃.

[0052] The tertiary formation solution consists of 0.5 g / L to 1.0 g / L citric acid and 0.3 g / L to 0.8 g / L triammonium citrate; the current density for the tertiary formation operation is 60 mA / cm². 2 ~80mA / cm 2 The voltage is 470V~500V, the time is 8min~10min, and the temperature is 85℃~90℃.

[0053] The quaternary formation solution consists of 0.50 g / L to 0.70 g / L ammonium azelate and 0.80 g / L to 1.0 g / L azelic acid; the current density for the quaternary formation operation is 60 mA / cm². 2 ~80mA / cm 2 The voltage is 580V~600V, the time is 8min~10min, and the temperature is 85℃~90℃.

[0054] The pentode formation solution consists of 0.2 g / L to 0.30 g / L ammonium azelate and 0.7 g / L to 1.0 g / L azelic acid; the current density for the pentode formation operation is 60 mA / cm². 2 ~80mA / cm 2 The voltage is 630V~650V, the time is 8min~10min, and the temperature is 85℃~90℃.

[0055] The formation solution for the hexa-ion formation operation includes 0.40 g / L to 0.55 g / L ammonium pentaborate and 45 g / L to 55 g / L boric acid; the current density for the hexa-ion formation operation is 60 mA / cm². 2 ~80mA / cm2 The voltage is 650V~670V, the time is 4min~6min, and the temperature is 85℃~90℃.

[0056] This application performs a multi-stage alumina formation process on aluminum foil, which continuously thickens and densifies the alumina film on the surface of the aluminum foil, further improving the performance of the oxide film, such as its pressure resistance and dielectric constant.

[0057] It should be noted that after each formation process, the aluminum foil needs to be rinsed with pure water to ensure the cleanliness of the foil surface. Optionally, the rinsing method includes immersing the formed aluminum foil in pure water and thoroughly rinsing the surface with running pure water. The rinsing time can be 5 to 8 minutes, and the resistivity of the pure water should not be less than 2.0 MΩ·cm. After rinsing, the aluminum foil removes the forming solution adhering to its surface, preventing residual forming solution from adversely affecting subsequent formation steps and ensuring the independence of each formation step and the stability of product quality.

[0058] Understandably, appropriate post-processing operations can be selected based on the processing requirements of the aluminum foil. For example, chemical treatment, repair formation, and heat treatment can be performed. For instance, chemical treatment of the aluminum foil using a chemical solution (such as one containing phosphates and silicates) can react chemically with the oxide film on the aluminum foil surface, thereby further modifying and altering the oxide film, optimizing its surface properties, such as reducing surface roughness and improving its adhesion to subsequent repair formation layers. Repair formation of the aluminum foil using a formation solution can repair damage to the oxide film caused by heat treatment or chemical treatment, further thicken the oxide film, and adjust its composition and structure to improve its pressure resistance and electrical properties.

[0059] It should be noted that after chemical treatment, the aluminum foil is cleaned with pure water to remove any residual chemical solution from the surface and prevent it from interfering with subsequent steps. After the repair formation process, the aluminum foil is cleaned with pure water to avoid residual formation solution affecting the foil's performance. Optionally, the resistivity of the pure water should be no less than 2.0 MΩ·cm.

[0060] In some embodiments, the post-processing includes: a first chemical treatment, a first remediation formation, a third infrared heating treatment, a second chemical treatment, a second remediation formation, and a third chemical treatment performed sequentially.

[0061] This application utilizes a third infrared heating treatment to further optimize the performance of the oxide film, resulting in a more complete crystal structure, improved stability and reliability, and ensuring superior quality of the electroformed foil product. Furthermore, the high efficiency and uniformity of infrared heating are used to heat-treat the oxide film on the aluminum foil surface. Infrared heating also induces physical and chemical changes in the oxide film, promoting densification and crystallization, improving its compressive strength, insulation properties, and stability, while simultaneously enhancing the adhesion between the oxide film and the aluminum foil substrate and reducing defects and cracks in the oxide film.

[0062] The third infrared heating treatment is performed at a temperature of 450℃ to 550℃, for example, 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, 510℃, 520℃, 530℃, 540℃, or 550℃. The duration is 30s to 70s, for example, 30s, 35s, 40s, 45s, 50s, 55s, 60s, 65s, or 70s. The wavelength of the infrared radiation is 2.5μm to 6.5μm, for example, 2.5μm, 3.0μm, 3.5μm, 4.0μm, 4.5μm, 5.0μm, 5.5μm, 6.0μm, or 6.5μm. This third infrared heating treatment, performed as described above, can further improve the density and uniformity of the oxide film.

[0063] The first chemical treatment solution consisted of 60 g / L to 70 g / L phosphoric acid; the first chemical treatment lasted 4 to 5 minutes at a temperature of 65°C to 75°C. The first remediation formation used a remediation solution consisting of 0.40 g / L to 0.60 g / L ammonium pentaborate and 45 g / L to 55 g / L boric acid; the current density for the first remediation formation was 30 mA / cm². 2 ~40mA / cm 2 The voltage for the first chemical treatment was 650V~670V, the time was 2.5min~3.5min, and the temperature was 85℃~90℃. The second chemical treatment solution consisted of 6.0g / L~10g / L phosphoric acid; the second chemical treatment time was 4min~7min, and the temperature was 55℃~75℃. The second remediation solution consisted of 0.40g / L~0.60g / L ammonium pentaborate and 45g / L~55g / L boric acid; the current density for the second remediation was 30mA / cm². 2 ~40mA / cm 2 The voltage is 640V~660V, the time is 2.5min~3.5min, and the temperature is 85℃~90℃. The treatment solution for the third chemical treatment includes 3.0g / L~8.0g / L ammonium dihydrogen phosphate; the time for the third chemical treatment is 3min~6min, and the temperature is 20℃~75℃.

[0064] In some embodiments, the post-processing further includes drying the aluminum foil after the third chemical treatment. Optionally, the drying temperature is 110°C to 150°C, and the time is 1 min to 3 min. Drying removes residual moisture from the aluminum foil surface, preventing moisture from adversely affecting the foil's performance and subsequent use, and ensuring the quality and stability of the formed foil product.

[0065] For the drying process, a hot air circulating drying oven can be used to ensure that the aluminum foil is heated evenly during the drying process, resulting in good drying effect. The drying oven should be equipped with a temperature, humidity, and airflow control system to optimize the drying process parameters.

[0066] Exemplarily, a method for preparing the above-described electrolytic foil is provided, comprising the following steps:

[0067] High-temperature water washing: Place the etched aluminum foil in pure water and heat at 90℃~100℃ for 5min~15min.

[0068] First-stage formation process: The etched aluminum foil is placed in a formation solution containing 1.2 g / L~2.5 g / L ammonium dihydrogen phosphate, 0.5 g / L~1.1 g / L citric acid, and 0.5 g / L~1.1 g / L triammonium citrate, under a current density of 60 mA / cm². 2 ~80mA / cm 2 The first-order electron formation operation was performed at a voltage of 140V~200V and a temperature of 85℃~90℃ for 8min~10min, followed by cleaning with pure water.

[0069] Secondary electron formation operation: The etched aluminum foil after the primary electron formation operation is placed in a formation solution containing 0.3 g / L~0.7 g / L ammonium dihydrogen phosphate, 0.5 g / L~1.1 g / L citric acid, and 0.5 g / L~1.1 g / L triammonium citrate, and the current density is 60 mA / cm². 2~ 80mA / cm 2 The secondary cationic formation operation was performed at a voltage of 310V~340V and a processing temperature of 85℃~90℃ for 7min~11min, followed by rinsing with pure water.

[0070] Tertiary electron formation process: The etched aluminum foil after the secondary electron formation process is placed in a formation solution containing 0.5 g / L~1.0 g / L citric acid and 0.3 g / L~0.8 g / L triammonium citrate, and the current density is 60 mA / cm². 2 ~80mA / cm 2 The tertiary formation process is performed at a voltage of 470V~500V and a temperature of 85℃~90℃ for 8min~10min, followed by cleaning with pure water.

[0071] Quaternary electron formation process: The etched aluminum foil after tertiary electron formation is placed in a formation solution containing 0.50 g / L~0.70 g / L ammonium azelaate and 0.80 g / L~1.0 g / L azelaic acid, and the current density is 60 mA / cm². 2 ~80mA / cm 2 The quaternary catenary formation process is performed at a voltage of 580V~600V and a temperature of 85℃~90℃ for 8min~10min, followed by cleaning with pure water.

[0072] Second infrared heating treatment: The etched aluminum foil after the quaternary electron formation operation is subjected to infrared heating at a temperature of 300℃~350℃ for 50s~70s, and the wavelength of the infrared radiation is 3.5μm~7.0μm.

[0073] Fifth-order formation operation: The etched aluminum foil, after being heated by the second infrared radiation, is placed in a formation solution containing 0.2 g / L~0.30 g / L ammonium azelaate and 0.7 g / L~1.0 g / L azelaic acid, under a current density of 60 mA / cm². 2 ~80mA / cm 2 The five-stage electron formation process is performed at a voltage of 630V~650V and a temperature of 85℃~90℃ for 8min~10min, followed by cleaning with pure water.

[0074] Sixth-stage electron formation operation: The etched aluminum foil after the fifth-stage electron formation operation is placed in a formation solution containing 0.40 g / L~0.55 g / L ammonium pentaborate and 45 g / L~55 g / L boric acid, and the current density is 60 mA / cm². 2 ~80mA / cm 2 The six-stage catenary formation process is performed at a voltage of 650V~670V and a temperature of 85℃~90℃ for 4min~6min, followed by rinsing with pure water.

[0075] First infrared heating treatment: The etched aluminum foil after the sixth-order electron formation operation is heated with infrared light at a temperature of 400℃~450℃ for 30s~70s, and the wavelength of the infrared light is 3.0μm~6.5μm.

[0076] First chemical treatment: The etched aluminum foil after the first infrared heat treatment is placed in a treatment solution of 60g / L~70g / L phosphoric acid and subjected to the first chemical treatment at 65℃~75℃ for 4min~5min, and then rinsed with pure water.

[0077] First repair process: The etched aluminum foil after the first chemical treatment is placed in a repair solution containing 0.40 g / L~0.60 g / L ammonium pentaborate and 45 g / L~55 g / L boric acid, under a current density of 30 mA / cm². 2 ~40mA / cm2 The first repair process is carried out at a voltage of 650V~670V and a temperature of 85℃~90℃ for 2.5min~3.5min, followed by rinsing with pure water.

[0078] The third infrared heating treatment: The corroded aluminum foil after the first repair formation is heated with infrared light at a temperature of 450℃~550℃ for 30s~70s, and the wavelength of the infrared light is 2.5μm~6.5μm.

[0079] Second chemical treatment: The etched aluminum foil after the third infrared heating treatment is placed in a treatment solution of 6.0 g / L to 10 g / L phosphoric acid and subjected to a second chemical treatment at 55℃ to 75℃ for 4 min to 7 min, and then rinsed with pure water.

[0080] Second repair process: The etched aluminum foil after the second chemical treatment is placed in a repair solution containing 0.40 g / L~0.60 g / L ammonium pentaborate and 45 g / L~55 g / L boric acid, at 30 mA / cm 2 ~40mA / cm 2 The second repair process is carried out at a voltage of 640V~660V and a temperature of 85℃~90℃ for 2.5min~3.5min, followed by rinsing with pure water.

[0081] Third chemical treatment: The corroded aluminum foil after the second repair is placed in a treatment solution of 3.0 g / L to 8.0 g / L ammonium dihydrogen phosphate and subjected to a third chemical treatment at a temperature of 20℃ to 75℃ for 3 min to 6 min, and then rinsed with pure water.

[0082] Drying treatment: The etched aluminum foil after the third chemical treatment is dried at 110℃~150℃ for 1min~3min to prepare etched foil.

[0083] The second aspect of this application provides a chemically formed foil, which is prepared using the chemically formed foil preparation method described in the first aspect.

[0084] In one embodiment, the thickness of the formed foil is 80 μm to 150 μm, and the width is 50 cm to 60 cm. The withstand voltage deviation of the formed foil is less than 5V; the capacitance deviation is less than 0.64%; the bending deviation is less than 20%; and the leakage current is less than 40 μA / cm. 2 .

[0085] It is understandable that the foil formed in this application can be applied to electrolytic capacitors.

[0086] Optionally, the electrolytic foil can be applied to leaded, horn-shaped, and bolt-shaped aluminum electrolytic capacitors. Furthermore, the capacitors can be used in circuit environments requiring high ripple current tolerance, such as industrial frequency converters, variable frequency air conditioners, and 5G base stations.

[0087] The embodiments of this application will be described in detail below with reference to examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this application, or follow experimental manuals or conventional conditions in the art, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0088] In the following examples and comparative examples, the thickness of the etched aluminum foil was 125μm~127μm, the bending was >50 times, and C 640V 0.60 μf / cm 2 ~0.62μf / cm 2 C 640V This refers to the capacitance measured after the etched foil has undergone 640V small-scale formation.

[0089] Example 1

[0090] High-temperature water washing: Place the etched aluminum foil in pure water and heat at 100°C for 14 minutes.

[0091] First-stage formation process: The etched aluminum foil is placed in a formation solution comprising 1.6 g / L ammonium dihydrogen phosphate, 0.8 g / L citric acid, and 0.8 g / L triammonium citrate, and the current density is 68 mA / cm². 2 ~70mA / cm 2 The first-order electron formation operation was performed at a voltage of 160V~180V and a temperature of 85℃~90℃ for 9 minutes, followed by rinsing with pure water with a resistivity of not less than 2.0MΩ·cm for 5 minutes.

[0092] Secondary electron formation operation: The etched aluminum foil after the primary electron formation operation is placed in a formation solution containing 0.5 g / L ammonium dihydrogen phosphate, 0.7 g / L citric acid, and 0.7 g / L triammonium citrate, and the current density is 68 mA / cm². 2~ 70mA / cm 2 The secondary electron formation operation was performed at a voltage of 320V~330V and a processing temperature of 85℃~90℃ for 9 minutes, followed by rinsing with pure water with a resistivity of not less than 2.0MΩ·cm for 5 minutes.

[0093] Tertiary electron formation process: The etched aluminum foil after the secondary electron formation process is placed in a formation solution containing 0.65 g / L citric acid and 0.65 g / L triammonium citrate, and the current density is 70 mA / cm². 2 ~75mA / cm 2The tertiary formation operation was performed at a voltage of 500V~510V and a temperature of 85℃~90℃ for 8min~9min, followed by rinsing with pure water with a resistivity of not less than 2.0MΩ·cm for 5min.

[0094] Quaternary electron formation process: The etched aluminum foil after the tertiary electron formation process is placed in a formation solution containing 0.60 g / L ammonium azelaate and 0.9 g / L azelaic acid, and the current density is 65 mA / cm². 2 ~68mA / cm 2 The quaternary electron formation operation was performed at a voltage of 590V~600V and a temperature of 85℃~90℃ for 9 minutes, followed by rinsing with pure water with a resistivity of not less than 2.0MΩ·cm for 5 minutes.

[0095] Second infrared heating treatment: The etched aluminum foil after the quaternary electron formation operation was subjected to infrared heating at a temperature of 340℃~350℃ for 50s. The wavelength of the infrared radiation was 4μm~5μm. The maximum temperature deviation on the surface of the aluminum foil was detected to be 13℃.

[0096] Fifth-stage formation process: The etched aluminum foil, after being heated by the second infrared radiation, is placed in a formation solution containing 0.24 g / L ammonium azelaate and 0.78 g / L azelaic acid, at a current density of 70 mA / cm². 2 ~75mA / cm 2 The five-stage electron formation process was performed at a voltage of 640V~650V and a temperature of 85℃~90℃ for 9 minutes, followed by rinsing with pure water with a resistivity of not less than 2.0MΩ·cm for 5 minutes.

[0097] Sixth-stage electron formation operation: The etched aluminum foil after the fifth-stage electron formation operation is placed in a formation solution containing 0.5 g / L ammonium pentaborate and 50 g / L boric acid, and the current density is 70 mA / cm². 2 The six-stage electron formation operation was performed at a voltage of 660V and a temperature of 85℃~90℃ for 5 minutes, followed by rinsing with pure water with a resistivity of not less than 2.0MΩ·cm for 5 minutes.

[0098] First infrared heating treatment: The etched aluminum foil after the sixth-order electron formation operation was heated with infrared light at a temperature of 430℃~450℃ for 50s. The wavelength of the infrared light was 3.5μm~4.5μm. The maximum temperature deviation on the surface of the aluminum foil was detected to be 15℃.

[0099] First chemical treatment: The etched aluminum foil after the first infrared heating treatment is placed in a treatment solution of 70 g / L phosphoric acid and subjected to the first chemical treatment at 65℃~68℃ for 5 min, and then rinsed with pure water with a resistivity of not less than 2.0 MΩ·cm for 5 min.

[0100] First repair formation: The etched aluminum foil after the first chemical treatment is placed in a repair solution containing 0.50 g / L ammonium pentaborate and 50 g / L boric acid, under a current density of 35 mA / cm². 2 ~40mA / cm 2 The first repair process is carried out at a voltage of 650V~660V and a temperature of 85℃~90℃ for 3.5 minutes, followed by rinsing with pure water with a resistivity of not less than 2.0MΩ·cm for 5 minutes.

[0101] The third infrared heating treatment: The corroded aluminum foil after the first repair formation was heated with infrared light at a temperature of 530℃~550℃ for 60s. The wavelength of the infrared light was 3.0μm~4.0μm. The maximum temperature deviation on the surface of the aluminum foil was detected to be 15℃.

[0102] Second chemical treatment: The etched aluminum foil after the third infrared heating treatment is placed in a treatment solution of 8.0 g / L phosphoric acid and subjected to a second chemical treatment at 63℃~65℃ for 6 min. Then it is washed with pure water with a resistivity of not less than 2.0 MΩ·cm for 5 min.

[0103] Second repair process: The etched aluminum foil after the second chemical treatment is placed in a repair solution containing 0.50 g / L ammonium pentaborate and 50 g / L boric acid, at 35 mA / cm². 2 ~40mA / cm 2 The second repair process is carried out at a voltage of 650V~660V and a temperature of 85℃~90℃ for 3.5 minutes, followed by rinsing with pure water with a resistivity of not less than 2.0MΩ·cm for 5 minutes.

[0104] Third chemical treatment: The corroded aluminum foil after the second repair formation is placed in a treatment solution of 5.1 g / L ammonium dihydrogen phosphate and subjected to a third chemical treatment at a temperature of 55℃~65℃ for 6 min. Then, it is rinsed with pure water with a resistivity of not less than 2.0 MΩ·cm for 5 min.

[0105] Drying treatment: The etched aluminum foil after the third chemical treatment is dried at 140℃~180℃ for 3 minutes to obtain the desired product. Figure 1 and Figure 2 It turns into foil.

[0106] Example 2

[0107] The electroformed foil was prepared according to the method of Example 1, except that a second infrared heating treatment was not performed.

[0108] Example 3

[0109] The aluminum foil was prepared according to the method of Example 1, except that the third infrared heating treatment was replaced by resistance furnace heating treatment, the heating temperature was set to 530℃~550℃ and the time was 60s, and the maximum temperature deviation on the surface of the aluminum foil was detected to be 40℃.

[0110] Comparative Example 1

[0111] The aluminum foil was prepared according to the method of Example 2, except that the first infrared heating treatment was replaced with the first resistance heating treatment, the heating temperature was set to 450°C, and the time was 90s~100s, and the maximum temperature deviation on the aluminum foil surface was detected to be 36°C; furthermore, the third infrared heating treatment was replaced with the second resistance heating treatment, the heating temperature was set to 540°C~550°C, and the time was 80s~90s, and the maximum temperature deviation on the aluminum foil surface was detected to be 41°C. The resulting aluminum foil was as shown in Example 2. Figure 3 and Figure 4 It turns into foil.

[0112] The formed foils prepared in the above embodiments and comparative examples were subjected to performance testing. The testing methods included:

[0113] The electroformed foil was tested according to the SJ / T11140-2022 standard, and the test results are shown in Table 1.

[0114] Table 1

[0115]

[0116] As can be seen from the table above:

[0117] (1) Compared with Example 2, Example 1 incorporates infrared heating treatment during the formation process, which helps to eliminate stress inside the oxide film, improve the crystal structure of the oxide film, and enhance the density and stability of the oxide film, thus creating favorable conditions for subsequent formation.

[0118] (2) Compared with Example 3, Example 1 shows that compared with resistance heating, this application uses third infrared treatment to cause physical and chemical changes in the oxide film on the surface of aluminum foil, promote the densification and crystallization of the oxide film, improve the pressure resistance, insulation performance and stability of the oxide film, and at the same time improve the bonding force between the oxide film and the aluminum foil substrate, and reduce the defects and cracks of the oxide film.

[0119] (3) Compared with Comparative Example 1, it can be seen that the formed foil prepared in Example 1 of this application has a 0.32% increase in capacity, a 42.5% decrease in capacity deviation, a 0.45% increase in withstand voltage, a 50% decrease in withstand voltage deviation, an 11.36% increase in the number of bends, and a 70.37% decrease in bend deviation compared with the formed foil prepared in Comparative Example 1. Furthermore, in conjunction with… Figure 1 and Figure 3 It can be seen that the alumina crystals obtained in Example 1 of this application have significantly better size uniformity than those in Comparative Example 1; combined with Figure 2 and Figure 4 It can be seen that the oxide film obtained in Example 1 of this application has a smoother surface and a significantly reduced number of micropores.

[0120] Therefore, this application employs infrared heating during the preparation of the aluminum foil, which enables uniform heating of the aluminum foil surface, optimizes the crystalline structure and chemical stability of the oxide film, facilitates the formation of a dense and uniform oxide film, reduces oxide film defects, improves the bending performance of the aluminum foil, and reduces the transverse withstand voltage difference and specific capacitance dispersion. Furthermore, infrared heating technology offers advantages such as high heating efficiency, fast heating speed, uniform temperature, good controllability, and low energy consumption, significantly shortening the heat treatment time for the aluminum foil, improving production efficiency, and reducing costs.

[0121] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0122] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A method for preparing a metallized foil, characterized in that, The preparation method includes: sequentially performing a formation treatment, a first infrared heating treatment, and a post-treatment on the etched aluminum foil to prepare the formed foil.

2. The method for preparing the electroformed foil as described in claim 1, characterized in that, The temperature of the first infrared heating treatment is 400℃~450℃, the time is 30s~70s, and the wavelength of the infrared radiation is 3.0μm~6.5μm.

3. The method for preparing the electroformed foil as described in claim 1, characterized in that, The formation process includes a first-stage formation operation, a second infrared heating treatment, and a second-stage formation operation performed sequentially.

4. The method for preparing the electroformed foil as described in claim 3, characterized in that, The second infrared heating treatment is performed at a temperature of 300℃~350℃ for 50s~70s, and the infrared wavelength is 3.5μm~7.0μm.

5. The method for preparing the electroformed foil as described in claim 3 or 4, characterized in that, The first-level transformation operation includes a first-level sub-transformation operation, a second-level sub-transformation operation, a third-level sub-transformation operation, and a fourth-level sub-transformation operation performed sequentially. And / or, the secondary formation operation includes a fifth-level sub-formation operation and a sixth-level sub-formation operation performed sequentially.

6. The method for preparing the electroformed foil as described in claim 5, characterized in that, The formation process also satisfies at least one of the following conditions: (1) The formation solution for the primary electron formation operation includes 1.2 g / L to 2.5 g / L ammonium dihydrogen phosphate, 0.5 g / L to 1.1 g / L citric acid, and 0.5 g / L to 1.1 g / L triammonium citrate; the current density for the primary electron formation operation is 60 mA / cm². 2 ~80mA / cm 2 The voltage is 140V~200V, the time is 8min~10min, and the temperature is 85℃~90℃; (2) The formation solution for the secondary sub-sub ... 2~ 80mA / cm 2 The voltage is 310V~340V, the time is 7min~11min, and the processing temperature is 85℃~90℃; (3) The forming solution for the tertiary formation operation includes 0.5 g / L to 1.0 g / L citric acid and 0.3 g / L to 0.8 g / L triammonium citrate; the current density for the tertiary formation operation is 60 mA / cm². 2 ~80mA / cm 2 The voltage is 470V~500V, the time is 8min~10min, and the temperature is 85℃~90℃; (4) The forming solution for the quaternary electron formation operation includes 0.50 g / L to 0.70 g / L ammonium azelate and 0.80 g / L to 1.0 g / L azelic acid; the current density for the quaternary electron formation operation is 60 mA / cm². 2 ~80mA / cm 2 The voltage is 580V~600V, the time is 8min~10min, and the temperature is 85℃~90℃; (5) The forming solution for the quintic formation operation comprises 0.2 g / L to 0.30 g / L ammonium azelate and 0.7 g / L to 1.0 g / L azelic acid; the current density for the quintic formation operation is 60 mA / cm². 2 ~80mA / cm 2 The voltage is 630V~650V, the time is 8min~10min, and the temperature is 85℃~90℃; (6) The formation solution for the sixth-order sub-formation operation comprises 0.40 g / L to 0.55 g / L ammonium pentaborate and 45 g / L to 55 g / L boric acid; the current density for the sixth-order sub-formation operation is 60 mA / cm². 2 ~80mA / cm 2 The voltage is 650V~670V, the time is 4min~6min, and the temperature is 85℃~90℃.

7. The method for preparing the electroformed foil according to any one of claims 1-4, characterized in that, The post-processing includes: a first chemical treatment, a first repair formation, a third infrared heating treatment, a second chemical treatment, a second repair formation, and a third chemical treatment performed sequentially.

8. The method for preparing the electroformed foil as described in claim 7, characterized in that, The third infrared heating treatment is performed at a temperature of 450℃~550℃ for a time of 30s~70s, with an infrared wavelength of 2.5μm~6.5μm.

9. The method for preparing the electroformed foil as described in claim 7, characterized in that, The post-processing also satisfies at least one of the following conditions: (1) The treatment solution for the first chemical treatment includes 60 g / L to 70 g / L phosphoric acid; the time of the first chemical treatment is 4 min to 5 min, and the temperature is 65℃ to 75℃; (2) The repair solution used in the first repair formation includes 0.40 g / L to 0.60 g / L ammonium pentaborate and 45 g / L to 55 g / L boric acid; the current density of the first repair formation is 30 mA / cm². 2 ~40mA / cm 2 The voltage is 650V~670V, the time is 2.5min~3.5min, and the temperature is 85℃~90℃; (3) The treatment solution for the second chemical treatment includes 6.0 g / L to 10 g / L phosphoric acid; the second chemical treatment time is 4 min to 7 min, and the temperature is 55℃ to 75℃; (4) The repair solution used in the second repair formation includes 0.40 g / L to 0.60 g / L ammonium pentaborate and 45 g / L to 55 g / L boric acid; the current density of the second repair formation is 30 mA / cm². 2 ~40mA / cm 2 The voltage is 640V~660V, the time is 2.5min~3.5min, and the temperature is 85℃~90℃; (5) The treatment solution of the third chemical treatment includes 3.0 g / L to 8.0 g / L ammonium dihydrogen phosphate; the time of the third chemical treatment is 3 min to 6 min, and the temperature is 20℃ to 75℃.

10. A type of electrolytic foil, characterized in that, It is prepared by the method for preparing chemically formed foil according to any one of claims 1-9.

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