Production process for forming cathode foil from bright foil

Abstract

The invention relates to a production process for forming a cathode foil from a polished foil, which comprises the following steps of: providing a roll of polished foil, and marking two side surfaces of the polished foil as a first surface and a second surface respectively; a plurality of adhesive tapes are wound on the light foil at intervals, the adhesive tapes wrap the first surface, the second surface and the side face of the light foil in the winding direction, and interval areas between the adjacent adhesive tapes are unwrapped areas; putting the bright foil into a washing tank for electrochemical corrosion, wherein the uncoated area is subjected to electrochemical corrosion to form a corrosion section; after the adhesive tapes wound on the light foil are torn down, the light foil is cleaned and dried in sequence to form a cathode foil, and a connecting section is formed in a covered area before the adhesive tapes are torn down on the cathode foil; wherein the connecting section is used for riveting a tab on the cathode foil.

Description

Technical Field

[0001] This invention relates to the field of capacitor manufacturing technology, and more particularly to a production process for forming cathode foil from optical foil. Background Technology

[0002] The performance of an electrolytic capacitor is determined by the anode foil, electrolyte, and cathode foil. The cathode foil primarily acts as the current collection layer, its core function being to provide a large surface area for sufficient contact with the electrolyte, forming a low-impedance conductive circuit. Therefore, the performance of the cathode foil, especially its equivalent series resistance and high-frequency characteristics, directly determines the capacitor's performance in high-speed charging and discharging circuits.

[0003] To reduce the equivalent series resistance, the cathode foil needs to undergo electrochemical etching to increase its specific surface area. Traditional cathode foil tab connections commonly employ a process similar to that of anode foil, involving pre-reserving a blank foil area at one end of the foil and subsequently mechanically riveting the aluminum tabs to that location. However, when this process is applied to cathode foil, the contact resistance introduced by the mechanical riveting points constitutes a major component of the capacitor's overall equivalent series resistance. In high-frequency, high-ripple current applications such as switching power supplies and processor decoupling, this resistance leads to severe capacitor overheating, significantly limiting overall efficiency and power density, becoming a performance ceiling that traditional processes cannot overcome. Furthermore, the cathode foil exhibits relatively low structural strength after etching, making it susceptible to collapse or microcracks from subsequent riveting impacts, affecting the capacitor's long-term reliability. Simultaneously, the loose oxide film formed by the low-voltage formation process on the cathode foil further degrades the connection quality of the riveting points, resulting in unstable contact resistance. Finally, the pre-reserved blank foil area on the cathode foil requires precise masking, reducing the effective utilization length of the foil and hindering cost optimization.

[0004] Therefore, it is necessary to provide a manufacturing process for forming cathode foil from light foil that can effectively reduce contact resistance and improve cathode foil discharge efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a manufacturing process for forming cathode foil from light-sensitive foil, which can effectively reduce contact resistance and improve cathode foil discharge efficiency.

[0006] According to one aspect of this application, a manufacturing process for forming a cathode foil from optical foil is provided, the manufacturing process comprising the steps of:

[0007] S10 provides a roll of optical foil, the two sides of which are respectively referred to as the first surface and the second surface;

[0008] S20. Several tapes are wound at intervals on the optical foil. The tapes cover the first surface, the second surface and the side of the optical foil along the winding direction. The interval area between adjacent tapes is the uncovered area.

[0009] S30 The optical foil is placed in a washing tank for electrochemical corrosion, and the uncoated area is electrochemically corroded by the electrolyte to form a corrosion segment;

[0010] After S40 tears off several pieces of adhesive tape wrapped around the optical foil, the optical foil is cleaned and dried in sequence to form a cathode foil. A connecting section is formed in the area covered by the adhesive tape before the cathode foil is torn off.

[0011] The connecting section is used to rivet tabs onto the cathode foil.

[0012] More preferably, in step S20, the material forming the tape is any one or a combination of epoxy resin, polyimide, or rubber.

[0013] More preferably, in step S20, when viewed along a direction perpendicular to the side of the foil, the spacing between adjacent adhesive tapes is equal, and the width of each uncoated area is also equal.

[0014] More preferably, in step S20, when viewed along a direction perpendicular to the side of the foil, the widths of the tapes are equal.

[0015] More preferably, in step S30, when viewed along a direction perpendicular to the side of the foil, the width of each etched segment is equal.

[0016] More preferably, in step S40, when viewed along a direction perpendicular to the side of the foil, the width of each connecting segment is equal.

[0017] More preferably, after step S30, the method further includes the step of:

[0018] The foil is subjected to low-pressure oxidation, and a thin oxide film is formed on the surface of the etched section.

[0019] More preferably, the connecting section is a smooth metal area that has not been corroded, and the connecting section and the corroded section are an integral structure.

[0020] The present invention has the following beneficial effects:

[0021] By pre-wrapping acid- and alkali-resistant tape around the cathode foil in a three-dimensional manner, the area of ​​the foil tightly covered by the tape is completely isolated from electrolyte erosion during the subsequent electrochemical etching process. This ensures that the foil maintains its original pure metallic state, directly forming a clean, low-resistance, and structurally complete integrated connection segment. The process of first covering the entire foil with a mask, then etching, and finally removing the tape allows the cathode foil connection segment and the high-surface-area etched segment to be formed simultaneously in a single continuous process. This reduces the risk of collapse and micro-cracks caused by subsequent riveting impacts on the fragile etched structure. Furthermore, the clean, pure metal connection segment reduces the additional contact resistance at the riveting points, lowering the overall equivalent series resistance of the capacitor and improving the discharge performance of the finished capacitor. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a flowchart of the manufacturing process for forming cathode foil from optical foil according to one embodiment of this application;

[0024] Figure 2 This is a schematic diagram of the planar structure of the cathode foil described in one embodiment of this application;

[0025] Figure 3 for Figure 2 Enlarged view of point A in the middle;

[0026] Explanation of reference numerals: 100, cathode foil; 10, light foil; 11, etching section; 12, connecting section; 20, tape; S1, first surface; S2, second surface. Detailed Implementation

[0027] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0028] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0029] 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 in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0030] Please refer to Figure 1 - Figure 3 This application provides a manufacturing process for forming a cathode foil 100 from a light foil 10, the manufacturing process including the following steps:

[0031] S10 provides a roll of optical foil 10, the two sides of which are respectively referred to as the first surface S1 and the second surface S2.

[0032] S20 wraps a plurality of adhesive tapes 20 at intervals around the optical foil 10. The adhesive tapes 20 cover the first surface S1, the second surface S2 and the side surface of the optical foil 10 along the wrapping direction. The interval area between adjacent adhesive tapes 20 is the uncovered area.

[0033] S30 The foil 10 is placed in a washing tank for electrochemical corrosion, and the uncoated area is electrochemically corroded by the electrolyte to form a corrosion segment 11.

[0034] After S40 tears off the several tapes 20 wrapped around the optical foil 10, the optical foil 10 is cleaned and dried in sequence to form a cathode foil 100. A connecting section 12 is formed on the area covered by the tapes 20 before they were torn off the cathode foil 100.

[0035] The connecting section 12 is used to rivet tabs onto the cathode foil 100.

[0036] In step S10, a roll of high-purity aluminum foil 10 is provided, whose two flat surfaces provide a uniform substrate for subsequent tape wrapping and regional etching. The selection of high-purity aluminum is crucial because it not only ensures the final product has extremely low resistivity, providing an efficient current path, but its uniform material composition also guarantees that all unprotected areas undergo uniform electrochemical reactions in the subsequent etching process, forming etch pits with consistent microstructure and uniform distribution. This is a prerequisite for obtaining stable and high specific surface area etched sections 11. In step S20, selective etching precisely pre-fabricates a mask pattern on the surface of the foil 10. By wrapping the foil 10 with electrolyte-resistant tape 20 (such as epoxy resin, polyimide, or rubber) at specific intervals and widths, the tape 20 tightly covers the upper and lower surfaces and two sides of the foil 10 360 degrees. The areas covered by the tape 20 are protected in subsequent processes, while the uncovered areas between the tapes 20 are pre-defined as areas to be etched. The principle is to utilize the excellent chemical stability, adhesion, and flexibility of the adhesive tape 20 to form a physical barrier that is tightly bonded to the foil and completely sealed, thereby precisely separating the protected area and the exposed area in a corrosive environment. In step S30, the pre-applied adhesive tape 20 is used to immerse the foil 10 in a specific electrolyte and electrochemically etched by applying an electric current. The principle is that the foil 10 acts as the anode. Under the action of an electric field, the exposed uncoated aluminum atoms undergo an oxidation reaction and dissolve, thus forming etched sections 11 filled with micro-tunnels and pores in these areas. The areas tightly covered by the adhesive tape 20 are isolated from the electrolyte, and their aluminum does not react, thus remaining intact and directly determining the capacitance of the capacitor. In step S40, the cathode foil 100 structure is finally formed, and its surface cleanliness is ensured. After etching is completed, the adhesive tape 20, which serves as a temporary mask, is removed, revealing the un-etched original foil 10 area underneath, forming a smooth, high-mechanical-strength, and highly conductive connecting section 12. The subsequent cleaning and drying are to thoroughly remove residual electrolyte and impurities, preventing further oxidation or contamination. The resulting cathode foil 100 is an integrated structure composed of etched sections 11 and connecting sections 12 spaced apart. The etched sections 11, with their high specific surface area, are primarily responsible for providing a large capacitance, while the robust and smooth connecting sections 12 form the mechanical skeleton of the cathode foil 100 and provide an ideal connection platform for its low-resistance, high-reliability riveting to the tabs.

[0037] More preferably, in step S20, the material forming the tape 20 is any one or a combination of epoxy resin, polyimide, or rubber.

[0038] Among them, epoxy resin, polyimide and rubber have excellent chemical corrosion resistance, stable mechanical properties and reliable adhesion strength. They can form a durable and effective protective layer during the electrochemical corrosion process, ensuring that the area covered by tape 20 is completely isolated from the electrolyte. This allows for precise control of the boundary shape and size of the corrosion area. At the same time, these materials can be completely peeled off without residue after corrosion, ensuring the cleanliness and flatness of the surface of the connecting section 12, providing an ideal substrate surface for subsequent electrode lug riveting.

[0039] More preferably, in step S20, when viewed along a direction perpendicular to the side of the foil 10, the spacing between adjacent adhesive tapes 20 is equal, and the width of each uncovered area is also equal.

[0040] By maintaining the uniformity of the spacing of the tape 20 and the width of the uncoated area, it is ensured that the etched segments 11 formed after the subsequent electrochemical etching process have a consistent size and distribution density. This arrangement is intended to form a regularly alternating mask pattern on the surface of the foil 10, thereby ensuring that the specific surface area and capacitance of each segment of the cathode foil 100 remain uniform. At the same time, it allows the uncorroded connecting segments 12 to be distributed at equal intervals, providing uniform mechanical support strength and a stable current transmission path for the cathode foil 100.

[0041] More preferably, in step S20, when viewed along a direction perpendicular to the side of the optical foil 10, the widths of the plurality of adhesive tapes 20 are equal.

[0042] By maintaining the uniformity of the width of all tapes 20, the connecting segments 12 formed after the subsequent etching process can have the same size and mechanical strength, thereby ensuring that the overall structure of the cathode foil 100 is subjected to uniform stress, avoiding material breakage during processing due to local support strength differences, ensuring that the tapes 20 form a uniform mask protection area on the surface of the foil 10, and ensuring that the impedance characteristics of the current flowing through each connecting segment 12 are consistent, ultimately improving the reliability and performance consistency of the capacitor product.

[0043] More preferably, in step S30, when viewed along a direction perpendicular to the side of the foil 10, the width of each etched segment 11 is equal.

[0044] By maintaining the uniformity of the width of all etched sections 11, the capacitance distribution of each section of the cathode foil 100 is made highly consistent, thereby avoiding the problem of uneven electric field distribution caused by local capacitance differences. At the same time, it ensures that the impedance characteristics of the current flowing through the etched section 11 remain uniform, ultimately significantly improving the electrical performance of the capacitor product.

[0045] More preferably, in step S40, when viewed along a direction perpendicular to the side of the foil 10, the widths of each connecting segment 12 are equal.

[0046] By utilizing this uniform width distribution, the connecting segments 12 formed after removing the tape 20 can maintain completely consistent width dimensions. This allows the connecting segments 12 to form an equally spaced mechanical support network on the cathode foil 100. This provides uniform tensile strength and toughness to the overall structure, avoiding stress concentration-induced breakage during subsequent processing. It also ensures that the current has consistent resistance characteristics when flowing through each connecting segment 12, thereby guaranteeing the electrical connection reliability of the tab riveting points. Ultimately, this achieves a high degree of unity and optimization of the mechanical and electrical properties of the capacitor product.

[0047] More preferably, after step S30, the method further includes the step of:

[0048] The foil 10 is subjected to low-pressure oxidation, and a thin oxide film is formed on the surface of the etched section 11.

[0049] In this process, an extremely thin and dense oxide film is generated in situ on the surface of the corrosion section 11 through a low-pressure oxidation process. This dielectric film can effectively repair the surface defects generated during the electrochemical corrosion process and significantly improve its dielectric strength, thereby greatly reducing the leakage current of the cathode foil 100 in subsequent working processes, improving the withstand voltage performance and long-term working stability of the capacitor. At the same time, the oxide film is firmly bonded to the substrate and will not affect the original high specific surface area characteristics of the corrosion section 11. Ultimately, the electrical reliability of the product is significantly enhanced while maintaining high capacitance.

[0050] More preferably, the connecting segment 12 is a smooth metal area that has not been corroded, and the connecting segment 12 and the corroded segment 11 are an integral structure.

[0051] In this design, a functionally integrated composite structure is constructed on the cathode foil 100. The uncorroded smooth connecting section 12 fully retains the excellent structural strength and conductivity of the high-purity aluminum foil, providing an ideal mechanical anchoring point and a low-resistance conductive channel for the tab riveting. The structure integrally formed with the corroded section 11 completely eliminates the contact resistance and connection reliability problems caused by the interface of heterogeneous materials. At the same time, the periodic combination of the high-strength connecting section 12 and the high specific surface area corroded section 11 perfectly balances the dual goals of the capacitor's high capacitance requirement and high mechanical reliability, achieving synergistic optimization of function and structure.

[0052] By pre-wrapping acid- and alkali-resistant tape 20 at intervals on the cathode foil 100 for three-dimensional coating, the area of ​​the foil 10 tightly covered by the tape 20 can be completely isolated from electrolyte erosion during the subsequent electrochemical etching process, ensuring that it maintains the pure metallic state of the original foil 10. This directly forms a clean, low-resistance, and structurally complete integrated connection segment 12. The process of first coating the entire structure with a mask, then etching, and finally removing the tape 20 allows the connection segment 12 of the cathode foil 100 and the high-surface-area etched segment 11 to be formed simultaneously in a single continuous process. This reduces the risk of collapse and micro-cracks caused by subsequent riveting impacts on the fragile etched structure. Furthermore, the clean, pure metal connection segment 12 reduces the additional contact resistance at the riveting points, lowering the overall equivalent series resistance of the capacitor and improving the performance of the finished capacitor.

[0053] The embodiments described above are merely examples of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this 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 protection scope of this application.

Claims

1. A manufacturing process for forming a cathode foil from optical foil, characterized in that, The production process includes the following steps: S10 provides a roll of optical foil, the two sides of which are respectively referred to as the first surface and the second surface; S20 Several tapes are wound at intervals on the optical foil. The tapes cover the first surface, the second surface and the side of the optical foil along the winding direction. The interval area between adjacent tapes is the uncovered area. S30 The optical foil is placed in a washing tank for electrochemical corrosion, and the uncoated area is electrochemically corroded by the electrolyte to form a corrosion segment; After S40 tears off several pieces of adhesive tape wrapped around the optical foil, the optical foil is cleaned and dried in sequence to form a cathode foil. A connecting section is formed in the area covered by the adhesive tape before the cathode foil is torn off. The connecting section is used to rivet tabs onto the cathode foil.

2. The manufacturing process for forming a cathode foil from a light-emitting foil according to claim 1, characterized in that, In step S20, the material forming the tape is any one or a combination of epoxy resin, polyimide, or rubber.

3. The manufacturing process for forming a cathode foil from a light-emitting foil according to claim 2, characterized in that, In step S20, when viewed along a direction perpendicular to the side of the foil, the spacing between adjacent adhesive tapes is equal, and the width of each uncoated area is also equal.

4. The manufacturing process for forming a cathode foil from a light-emitting foil according to claim 3, characterized in that, In step S20, when viewed along a direction perpendicular to the side of the foil, the widths of several of the adhesive tapes are equal.

5. The manufacturing process for forming a cathode foil from a light-emitting foil according to claim 4, characterized in that, In step S30, when viewed along a direction perpendicular to the side of the foil, the width of each etched segment is equal.

6. The manufacturing process for forming a cathode foil from a light-emitting foil according to claim 5, characterized in that, In step S40, when viewed along a direction perpendicular to the side of the foil, the width of each connecting segment is equal.

7. The manufacturing process for forming a cathode foil from a light-emitting foil according to claim 6, characterized in that, Following step S30, the method further includes the following step: The foil is subjected to low-pressure oxidation, and a thin oxide film is formed on the surface of the etched section.

8. The manufacturing process for forming a cathode foil from a light-emitting foil according to claim 7, characterized in that, The connecting section is a smooth metal area that has not been corroded, and the connecting section and the corroded section are an integral structure.

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