Solid aluminum electrolytic capacitor guide pin surface coating process and capacitor

Abstract

The invention discloses a solid aluminum electrolytic capacitor guide pin surface coating process which comprises the following steps: S1, pretreating a guide pin of a solid aluminum electrolytic capacitor to clean the surface of the guide pin; s2, preparing a film coating liquid for forming an insulating isolating film, and coating the surface of the pretreated guide pin with the film coating liquid so as to form a layer of insulating isolating film on the surface of the guide pin; and S3, carrying out drying and curing treatment on the coated guide pin, so that the insulating isolating membrane is cured and formed. The method is simple in process steps, mainly comprises pretreatment, coating and curing, is easy to integrate into an existing production line, and does not need complex and expensive equipment. The raw materials of the film coating liquid are easy to obtain, and the cost is low. By designing special coating liquid components and optimizing a curing process, the formed insulating isolation film is strong in adhesive force and uniform and moderate in thickness, so that an excellent insulating isolation effect is ensured, and adverse effects on the conductivity of the guide pin and subsequent assembling and welding procedures are avoided.

Description

Technical Field

[0001] This invention relates to the field of electronic components technology, specifically to a coating process for the surface of the leads of a solid aluminum electrolytic capacitor and the capacitor itself. Background Technology

[0002] Solid aluminum electrolytic capacitors are widely used in modern electronic circuits due to their advantages such as low equivalent series resistance, excellent high-frequency performance, long lifespan, and good stability. Their basic structure typically includes an anode foil, a cathode foil, a core package formed by winding electrolytic paper, and lead pins connected to the anode and cathode foils respectively.

[0003] In the manufacturing process of solid aluminum electrolytic capacitors, impregnation is a critical step. This involves immersing the wound core package in a dispersion containing conductive polymer monomers, oxidants, and other components, allowing them to polymerize inside the core package to form a solid electrolyte. However, a significant problem exists in existing technologies: during impregnation, specific areas of the conductor pins (often referred to in the industry as part B) inevitably come into contact with the polymer dispersion and oxidants. Since the conductor pins are typically made of metal, direct contact with these chemicals can lead to unwanted chemical reactions, such as oxidation or corrosion, altering the surface condition of the pins. This change significantly increases the leakage current (LC value), severely degrading the capacitor's electrical performance, resulting in decreased yield and reduced product reliability.

[0004] Therefore, there is an urgent need to develop a simple, low-cost, and reliable surface treatment technology for conductors that can effectively isolate the impregnation liquid from direct contact with the conductors, thereby steadily reducing product leakage current and improving the overall performance and production yield of solid aluminum electrolytic capacitors. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a coating process for the surface of the conductor pins of solid aluminum electrolytic capacitors. This process forms a dense and robust insulating film on the surface of the conductor pins, physically preventing the polymer dispersion and oxidant in the impregnation process from contacting the metal surface of the conductor pins, thereby avoiding the chemical reactions that may result and effectively reducing the leakage current of the product.

[0006] Another object of the present invention is to provide a capacitor manufactured using the above-described process for the conductor pins. Because the conductor pins are effectively protected, the capacitor exhibits more stable electrical performance, significantly reduced leakage current, and improved product yield and reliability.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A coating process for the surface of the leads of a solid aluminum electrolytic capacitor includes the following steps: S1. Pre-treat the leads of the solid aluminum electrolytic capacitor to clean their surfaces. S2. Prepare a special coating solution and apply the coating solution to the pretreated guide needle surface to form an insulating film on the guide needle surface. S3. The coated guide needles are dried and cured to solidify the insulating film.

[0008] Furthermore, in step S1, the pretreatment step includes removing oil and impurities from the surface of the guide needle.

[0009] Furthermore, in step S2, the coating liquid contains a water-soluble solvent, a natural resin, and a film-forming aid.

[0010] Furthermore, in step S2, the coating method is any one of immersion coating, spray coating, or spin coating.

[0011] Furthermore, in step S2, the amount of coating liquid and coating parameters are controlled so that the thickness of the final insulating barrier film is controlled between 1 and 5 micrometers.

[0012] Furthermore, in step S3, the drying and curing process includes placing the coated guide needle in an oven for baking.

[0013] Furthermore, the baking process specifically involves: first, placing the guide pin in an oven at 60℃-70℃ and baking for 3 to 6 minutes, then raising the oven temperature to 160℃ and placing the guide pin in to continue baking for 3 to 6 minutes.

[0014] Furthermore, after the insulating separator is formed, the following steps are also included: S4, assembling the guide pins with the insulating separator solidified on the surface with the capacitor core, and completing the impregnation process according to the production process of solid aluminum electrolytic capacitors.

[0015] A solid aluminum electrolytic capacitor is prepared using a conductive pin surface coating process.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The process steps of this invention are simple, mainly including pretreatment, coating, and curing, and it is easy to integrate into existing production lines without the need for complex and expensive equipment. The raw materials used for the coating liquid are readily available and have low cost. By designing a dedicated coating liquid composition and optimizing the curing process, the resulting insulating film has strong adhesion and a uniform and moderate thickness, ensuring excellent insulation performance without adversely affecting the conductivity of the guide pin or subsequent assembly and welding processes.

[0017] 2. By utilizing the physical barrier effect of the insulating film, the direct reaction path between the impregnating liquid and the conductor pins is fundamentally cut off, thereby significantly reducing the leakage current of the solid aluminum electrolytic capacitor and improving the product's electrical performance parameters. Due to the effective control of leakage current, the product's yield rate is greatly improved. Simultaneously, the stable surface condition of the conductor pins also enhances the reliability of the capacitor during long-term use. Attached Figure Description

[0018] Figure 1 This is a flowchart of the coating process for the capacitor pin surface of the present invention; Figure 2 This image shows the finished product of the solid aluminum electrolytic capacitor leads prepared by the surface coating process of this invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] See Figure 1-2 As shown, the present invention provides a technical solution: a coating process for the surface of the conductive pins of a solid aluminum electrolytic capacitor, comprising the following steps: S1, Preprocessing The leads of solid aluminum electrolytic capacitors undergo pretreatment to clean their surfaces. This step aims to remove impurities such as oil, dust, and oxides that may have accumulated on the leads during initial processing and transportation. A clean surface is essential for ensuring the uniform coating and firm adhesion of the subsequent insulating film.

[0021] This step can begin with ultrasonic cleaning using an organic solvent, followed by activation of the guide pin surface using plasma treatment. The plasma cleaning process involves a power of 200-500W and a treatment time of 30-120 seconds. The organic solvent can be at least one of acetone, ethanol, or isopropanol. Plasma treatment not only thoroughly cleans the surface but also creates microscopic roughness on the guide pin surface, significantly improving the adhesion of the insulating film and preventing film detachment during subsequent impregnation or assembly.

[0022] S2. Preparation and application of coating solution A specialized coating solution is prepared, comprising a water-soluble solvent, a natural resin, and film-forming aids. The water-soluble solvent is environmentally friendly and low-cost; the natural resin possesses good film-forming and insulating properties; and the film-forming aids are used to improve leveling properties and enhance adhesion. The water-soluble solvent includes at least one of deionized water, ethanol, or isopropanol, and its mass percentage in the coating solution is 50%-80%. The natural resin includes at least one of rosin, shellac, or amber, and its mass percentage in the coating solution is 10%-30%. The film-forming aid includes at least one of a plasticizer, leveling agent, or defoamer, and its mass percentage in the coating solution is 5%-15%.

[0023] The prepared special coating solution is applied to the pretreated guide pin surface using a suitable coating method. Coating methods include immersion, spraying, or spin coating. Immersion is simple to operate and produces a uniform coating; spraying is highly efficient and suitable for automated production; spin coating yields an extremely uniform film. In practice, precise control of the coating solution dosage and coating parameters is required to ensure the final insulating film thickness is between 1 and 5 micrometers. This thickness should ensure effective electrical and physical insulation without excessively increasing the guide pin size or affecting its conductivity and subsequent product assembly.

[0024] In some embodiments, an appropriate amount of inorganic nano-insulating filler may be added to the coating solution. The inorganic nano-insulating filler accounts for 1%-3% of the mass percentage in the coating solution and includes at least one of nano-alumina or nano-silica, with a particle size ranging from 20 to 100 nanometers. When preparing the dedicated coating solution, the mixture containing the inorganic nano-insulating filler is ultrasonically dispersed to ensure uniform dispersion of the filler. After coating, the thickness of the insulating membrane is controlled between 2 and 5 micrometers. Utilizing the small size effect of nanomaterials, the microscopic defects of the polymer film layer are filled, forming a denser composite shielding layer. This composite membrane not only provides physical barrier but also effectively inhibits the migration and diffusion of oxidants and ions, thereby synergistically achieving the inventive objective of reducing the LC value.

[0025] S3, Drying and Curing After coating, the guide pins with the wet film are dried and cured to transform the liquid coating liquid into a solid insulating barrier film. The curing process is preferably carried out in an oven. The baking process includes: first, placing the coated guide pins in an oven at 60°C to 70°C, preferably 60°C, for pre-baking for 3 to 6 minutes, preferably 3 minutes; the main purpose of this stage is to allow the solvent to evaporate slowly, preventing bubbles or cracks in the film layer; subsequently, the guide pins are transferred to a high-temperature oven at 160°C and baked for another 3 minutes. This stage aims to fully cross-link and cure the film-forming substances such as natural resins, forming a tough and stable insulating film layer. To further optimize the curing conditions, the baking process is carried out in an inert gas atmosphere, with the inert gas being nitrogen or argon. Baking in an inert gas atmosphere prevents film oxidation and improves film quality.

[0026] S4, Subsequent Assembly After the insulating film has fully cured and solidified, the capacitor assembly stage can begin. The conductors with the insulating film cured on their surface are assembled with the wound capacitor core, and then the impregnation process is carried out according to the conventional solid aluminum electrolytic capacitor production process. At this point, because the critical parts of the conductors are protected by the insulating film, even if they come into contact with polymer dispersions and oxidants, no adverse reactions will occur, thus ensuring low leakage current in the product.

[0027] The process of this invention is simple, mainly including pretreatment, coating, and curing, and is easily integrated into existing production lines without the need for complex and expensive equipment. The raw materials used for the coating liquid are readily available and have low cost. By designing a dedicated coating liquid composition and optimizing the curing process, the resulting insulating film has strong adhesion and a uniform and moderate thickness, ensuring excellent insulation performance without adversely affecting the conductivity of the guide pin or subsequent assembly and welding processes.

[0028] This invention also provides a solid aluminum electrolytic capacitor, which is manufactured using a conductive pin surface coating process. Through the physical barrier effect of the insulating film, the direct reaction path between the impregnating liquid and the conductive pin is fundamentally cut off, thereby significantly reducing the leakage current of the solid aluminum electrolytic capacitor and improving the product's electrical performance parameters. Due to the effective control of leakage current, the product's yield rate is greatly improved. Simultaneously, the stable conductive pin surface condition also enhances the capacitor's reliability during long-term use.

[0029] Tests have shown that capacitors manufactured using the process of this invention to treat the conductors have an average leakage current that is about 80% lower than those of the same specifications produced with untreated conductors. Furthermore, the loss tangent, equivalent series resistance, and other parameters of the products remain excellent, fully verifying the effectiveness and superiority of this invention.

[0030] A parameterized comparison of the above embodiments with existing technologies shows that the solid aluminum electrolytic capacitor pin surface coating process provided by this invention is not a simple improvement, but a solution that can systematically enhance product quality. It brings significant and quantifiable beneficial effects in key electrical performance (leakage current), physical performance (adhesion), production yield, environmental friendliness, and cost control, making it particularly suitable for manufacturing high-performance, high-reliability solid aluminum electrolytic capacitors.

Claims

1. A process for coating the surface of a solid aluminum electrolytic capacitor lead pin, characterized by, The method comprises the following steps: S1. Pre-treating the lead pin of the solid aluminum electrolytic capacitor to clean the surface thereof; S2. Preparing a special coating solution, and coating the coating solution on the surface of the pre-treated lead pin to form an insulating isolation film on the surface of the lead pin; S3. Drying and curing the coated lead pin to solidify the insulating isolation film.

2. The solid-state aluminum electrolytic capacitor lead pin surface coating film process according to claim 1, characterized by, In step S1, the pre-treatment step comprises removing oil stains and impurities on the surface of the lead pin.

3. The solid-state aluminum electrolytic capacitor pin surface coating process according to claim 1, wherein In step S2, the coating solution comprises a water-soluble solvent, a natural resin, and a film-forming aid.

4. The solid-state aluminum electrolytic capacitor pin surface coating process according to claim 1, wherein In step S2, the coating method is any one of immersion, spraying, or spin coating.

5. The solid-state aluminum electrolytic capacitor pin surface coating process of claim 1, wherein, In step S2, the amount of the coating solution and the coating parameters are controlled so that the thickness of the finally formed insulating isolation film is controlled to be between 1-5 microns.

6. The solid-state aluminum electrolytic capacitor pin surface coating process of claim 1, wherein, In step S3, the drying and curing treatment comprises baking the coated lead pin in an oven.

7. The solid-state aluminum electrolytic capacitor lead pin surface coating film process according to claim 6, characterized by, The baking process specifically comprises: first baking the lead pin in an oven at 60-70°C for 3-6 minutes, and then increasing the temperature of the oven to 160°C and baking the lead pin for another 3-6 minutes.

8. The solid-state aluminum electrolytic capacitor pin surface coating process of claim 1, wherein, After the formation of the insulating isolation film, the following step S4 is further included: assembling the lead pin with the surface solidified with the insulating isolation film with a capacitor core package, and completing the impregnation process according to the production process of the solid aluminum electrolytic capacitor.

9. A solid electrolytic aluminum electrolytic capacitor characterized by The solid aluminum electrolytic capacitor is prepared by using the lead pin treated by the process of any one of claims 1-8.

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