High-performance aluminum electrolytic capacitor and manufacturing method thereof

Abstract

The invention discloses a high-performance aluminum electrolytic capacitor and a manufacturing method thereof, and relates to the technical field of capacitors. The manufacturing method comprises the following steps: selecting corresponding anode foil, cathode foil, electrolytic paper and foil guide strips according to product specifications; cutting the anode foil, the cathode foil and the electrolytic paper into appropriate sizes; the anode foil, the cathode foil, the electrolytic paper and the foil guide strip are sequentially placed on a riveting and rolling machine table device, and winding and fixing are carried out according to the anode foil-electrolytic paper-cathode foil structure to obtain a capacitor core; the capacitor core is dried; the dried capacitor core is placed in an impregnation cylinder containing an electrolyte, so that the capacitor core adsorbs a preset amount of electrolyte; and sealing the capacitor core containing the electrolyte by using an aluminum shell and a cover plate to obtain a finished product. According to the high-performance aluminum electrolytic capacitor provided by the invention, the number of the foil guide strips is increased, the contact area between the foil guide strips and the aluminum foil is increased, the product loss is reduced, the ripple resistance of the product is improved, and the performance of the capacitor is more stable.

Description

Technical Field

[0001] The present invention relates to the technical field of capacitors, and in particular to a high-performance aluminum electrolytic capacitor and a manufacturing method thereof. Background Art

[0002] Capacitors are an important electronic component whose basic function is to store and release electrical energy. The working principle of capacitors is to store electrical energy by storing charges on two electrodes. When there is a dielectric between conductors, the charges are forced to move in the electric field, which hinders the movement of charges and causes the charges to accumulate on the conductors, resulting in the accumulation of charges. Capacitors are similar to batteries and have two electrodes, which are connected to two metal plates separated by a dielectric.

[0003] Capacitors are widely used in circuits for DC isolation, AC passing, coupling, bypassing, filtering, tuning circuits, energy conversion, control, etc. The main application areas include household appliances, photovoltaic wind power, new energy storage, new energy vehicles, high-voltage SVG, industrial control, rail transit, power quality management, etc.

[0004] Some performance decays that may occur during the use of capacitors, such as temperature, humidity, air pressure and other environmental factors have a significant impact on the life of the capacitor. High temperature will accelerate the internal chemical reaction of the capacitor, leading to dielectric aging; excessive humidity may cause the capacitor to absorb moisture, affecting the insulation performance. Usually, what we call the end of the life of the capacitor refers to the capacitance dropping to about 80% of the rated initial value, and it is unable to bear the role of the capacitor in the circuit. In addition, the temperature rise causes the negative electrode liquid to gradually disappear. When it decreases to a certain extent, the capacitance falls below the threshold and the life ends. Another direct reason for the decrease in capacitor capacitance is that the actual area of ​​the aluminum electrolytic capacitor electrode is reduced due to high temperature, while the anode is basically unchanged during use, and the area is reduced by the cathode. The actual area of ​​the cathode is guaranteed by the electrolyte. If the electrolyte decreases due to volatilization, the actual cathode area will be reduced, and the capacitor life will also be reduced.

[0005] Common failure modes of capacitors include: breakdown, open circuit, changes in electrical parameters (including capacitance tolerance, insulation degradation or leakage current increase), leakage, lead corrosion or breakage, no capacity, insulator rupture, etc. There are many reasons for capacitor failure. Especially for capacitors with special requirements such as high ripple resistance, low ESR, long life, and reduced size, the material selection and manufacturing process requirements for capacitors will be more stringent.

[0006] How to increase the service life of capacitors, improve the capacitor's tolerance to temperature, humidity, and high operating voltage environments, and maintain good performance for a long time is of great significance to the application field of capacitors. It is urgent to obtain capacitors with high reliability and long service life to meet the performance requirements of capacitors. Summary of the invention

[0007] The technical problem to be solved by the present invention is how to increase the service life of the capacitor, improve the capacitor's tolerance to temperature, humidity, and high operating voltage environments, and maintain good performance for a long time.

[0008] In order to solve the above problems, the present invention proposes the following technical solutions:

[0009] In a first aspect, the present invention provides a method for manufacturing a high-performance aluminum electrolytic capacitor, comprising the following steps:

[0010] Material selection: select corresponding anode foil, cathode foil, electrolytic paper and foil guide strip according to product specifications;

[0011] Cutting: Cutting the anode foil, cathode foil and electrolytic paper into suitable sizes;

[0012] Winding: Place the anode foil, cathode foil, electrolytic paper and foil guide strip on the riveting and coiling machine in sequence, and wind and fix them in the structure of anode foil-electrolytic paper-cathode foil to obtain the capacitor core;

[0013] Drying: drying the capacitor core;

[0014] Impregnating the electrolyte: placing the dried capacitor core in an impregnation tank containing the electrolyte, so that the capacitor core absorbs a preset amount of electrolyte;

[0015] Assembly and sealing: The capacitor core containing the electrolyte is sealed with an aluminum shell and a cover plate to obtain a finished product;

[0016] The number of the foil guide strips of the capacitor core is 3-8 pairs.

[0017] A further technical solution is that the angle between the foil guide strip and the anode foil or cathode foil is 85°≦α≦95°.

[0018] A further technical solution is that the number of rivet points of the single foil guide strip is greater than 6.

[0019] A further technical solution is that the distance between the rivet point of the foil guide strip and the edge of the foil guide strip is greater than 1 mm.

[0020] A further technical solution is that in the slitting step, a tungsten steel knife is used to slit the anode foil and the cathode foil.

[0021] A further technical solution is that in the drying step, the drying conditions are 95±5°C for 1 to 3 hours.

[0022] A further technical solution is that in the electrolyte impregnation step, the impregnation parameters include making the vacuum degree of the impregnation cylinder less than -0.09MPa within 300s and maintaining the vacuum degree for impregnation, the pressure in the impregnation cylinder is 0.2-0.6MPa, and the impregnation temperature is 55-65°C.

[0023] A further technical solution is that the immersion time is 4 to 6 hours.

[0024] In a second aspect, the present invention provides a high-performance aluminum electrolytic capacitor, which is manufactured by the manufacturing method of the high-performance aluminum electrolytic capacitor described in the first aspect.

[0025] A further technical solution is that the storage environment temperature of the high-performance aluminum electrolytic capacitor is 5-30° C. and the humidity is below 75%.

[0026] Compared with the prior art, the technical effects achieved by the present invention include:

[0027] The high-performance aluminum electrolytic capacitor provided by the present invention increases the number of foil guides, can effectively increase the contact area between the foil guides and the cathode foil and the anode foil, reduces product loss and improves the ripple resistance of the product, and ensures more stable capacitor performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0029] Figure 1 It is a schematic diagram of the structure of the capacitor core of the electrolytic capacitor. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Similar component numbers in the drawings represent similar components. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0032] It should also be understood that the terms used in this description of the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present invention. As used in the description of the embodiments of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms of "a", "an" and "the" are intended to include plural forms.

[0033] Common failure modes of aluminum electrolytic capacitors include: breakdown, open circuit, changes in electrical parameters (including capacitance tolerance, insulation degradation or leakage current increase), leakage, lead corrosion or breakage, no capacity, insulator rupture, etc. There are many reasons for capacitor failure. Especially for capacitors with special requirements such as high ripple resistance, low ESR, long life, and reduced size, the requirements for capacitor material selection and manufacturing process are more stringent.

[0034] See also Figure 1 , which is a schematic diagram of the structure of the capacitor core of the electrolytic capacitor. The capacitor core mainly includes an anode foil, a cathode foil, electrolytic paper, an electrolyte and a foil conductor.

[0035] Anode Foil: Anode foil is the part of the capacitor that stores charge, usually made of aluminum or special alloys. In electrolytic capacitors, an oxide film is formed on the surface of the anode foil, which has a high dielectric constant and can store a large amount of charge.

[0036] Cathode Foil: Cathode foil is the other pole of the capacitor, which is usually made of aluminum and opposite to the anode foil. In electrolytic capacitors, the cathode foil is not in direct contact with the electrolyte, but is isolated from the anode foil by electrolytic paper.

[0037] Electrolytic paper (SeparatorPaper): Electrolytic paper is a highly insulating and absorbent material, usually made of cellulose. Its function is to isolate the anode foil and the cathode foil to prevent them from directly contacting and causing a short circuit, and it can absorb and retain the electrolyte.

[0038] Electrolyte: Electrolyte is the medium that provides ions in the capacitor. It can be in liquid or colloidal state. The ions in the electrolyte move under the action of the electric field, thus forming a current between the two plates of the capacitor.

[0039] Lead Foil: Lead foil is a conductive component that connects the capacitor core to the external circuit. They are usually made of metal, such as aluminum or copper, and are used to transfer the charge of the capacitor to the external circuit.

[0040] Anode foil, cathode foil, electrolytic paper, electrolyte and foil strips work together to enable capacitors to store and release electrical energy in a circuit. The performance of capacitors, such as capacitance, withstand voltage, leakage current, etc., are closely related to the material selection and manufacturing process of these components.

[0041] In this regard, an embodiment of the present invention provides a method for manufacturing a high-performance aluminum electrolytic capacitor, comprising the following steps:

[0042] Material selection: select corresponding anode foil, cathode foil, electrolytic paper and foil guide strip according to product specifications;

[0043] Cutting: Cutting the anode foil, cathode foil and electrolytic paper into suitable sizes;

[0044] Winding: Place the anode foil, cathode foil, electrolytic paper and foil guide strip on the riveting and coiling machine in sequence, and wind and fix them in the structure of anode foil-electrolytic paper-cathode foil to obtain the capacitor core;

[0045] Drying: drying the capacitor core;

[0046] Impregnating the electrolyte: placing the dried capacitor core in an impregnation tank containing the electrolyte, so that the capacitor core absorbs a preset amount of electrolyte;

[0047] Assembly and sealing: The capacitor core containing the electrolyte is sealed with an aluminum shell and a cover plate to obtain a finished product.

[0048] In the high-performance aluminum electrolytic capacitor prepared in this embodiment, the number of the conductive foil strips of the capacitor core is 3-8 pairs.

[0049] Regarding the above material selection steps, it should be noted that aluminum electrolytic capacitors are composed of two conductors (anode foil and cathode foil) close to each other with a layer of non-conductive insulating medium (electrolytic paper) in the middle. The capacitance of the capacitor is proportional to the effective surface area of ​​the anode foil and cathode foil, and inversely proportional to the thickness of the aluminum oxide film on the surface of the anode foil and cathode foil. In order to increase the capacitance of the capacitor, it is necessary to use a porous anode foil with a thin oxide film and good density. This type of anode foil has a high porosity, so its effective surface area is large, so the capacitor made with it has a high electrostatic capacitance.

[0050] The preparation of anode foil generally goes through two major processes: corrosion (displacing aluminum in aluminum foil through acid or current to form holes) and formation (forming a uniform, dense, insulating oxide film on the holes). The corrosion process determines the effective surface area of ​​the aluminum foil and affects the specific volume of the anode foil. The formation process determines the quality of the oxide film, affects important performance parameters such as the actual capacitance, loss, and leakage current of the capacitor, and is also the main factor that determines whether the capacitor is prone to open circuit or short circuit failure. Anode foils with different formation processes are suitable for different capacitors and need to be selected reasonably.

[0051] For example, for general horn products, the anode foil is usually prepared using a mixed acid process of inorganic acid and organic acid.

[0052] For example, for fast-moving consumer goods that require a higher capacity extraction rate, organic acid process is often used in the preparation of anode foil.

[0053] For example, for large ripple products, since the ripple current has a greater impact on the anode aluminum foil and generates more serious heat, the phosphoric acid process is generally used in the preparation of the anode foil. This is because the oxide film obtained by phosphoric acid contains aluminum phosphate, and the crystal form of aluminum phosphate is more stable and is not easy to change at high temperature.

[0054] By selecting corresponding anode foil, cathode foil, electrolytic paper and other materials according to product specifications, and using slitting equipment to slit them into the required material width.

[0055] It should be noted that during slitting, attention should be paid to the selection and inspection of the tool and the adjustment of the machine tension, because the slitting process will affect whether the cut will have burrs on the foil, wavy edges on the foil, or poor uniformity of the foil tray or paper tray. These problems will affect the performance of the final capacitor product.

[0056] For the preparation of high-performance aluminum electrolytic capacitors, the present invention uses a tungsten steel knife with high hardness, wear resistance, heat resistance, corrosion resistance, shock resistance, and a cutting speed 50%-100% higher than that of a white steel knife, and a durability 2-10 times higher to cut the aluminum foil (anode foil, cathode foil). Before cutting the material, a high-power magnifying glass is used to check the knife to ensure that the knife edge is flat and has no gaps, which can greatly reduce the occurrence of defective cutting products.

[0057] The foil ash on the surface of the slit anode foil and cathode foil should be processed as soon as possible. After checking that the anode foil and cathode foil meet the slitting standards, the foil trays should be separated with clean foam cotton in time, and the materials should be hung in a clean room with constant temperature and humidity for storage.

[0058] The high-performance aluminum electrolytic capacitor of the embodiment of the present invention optimizes the material selection of electrolytic paper, and the fiber distribution of the electrolytic paper is uniform. It is preferred to use a composite electrolytic paper obtained by compounding with a new slurry. In this embodiment, the thickness of the electrolytic paper is 30-50 μm, and the density is 0.40-0.80 g / cm 3 .

[0059] The manufacturing process of capacitor paper is complex and delicate, and it needs to meet requirements such as high purity, uniformity, mechanical and electrical strength, absorption, and voltage resistance. The key steps include:

[0060] Raw material selection: Select high-quality cellulose raw materials, such as wood pulp, agave fiber, grass fiber, and even special fibers such as Manila hemp fiber. Manila hemp fiber is used in the production of electrolytic capacitor paper because of its high strength, acid resistance, alkali resistance, heat resistance, and water resistance.

[0061] Pulping: The selected raw materials are made into pulp through processes such as cooking and bleaching.

[0062] Beating: The pulp is processed through a beater to adjust the fiber morphology and pulp concentration to achieve the desired physical properties.

[0063] Papermaking: The treated pulp is formed through a fourdrinier paper machine to control the concentration of the paper and the uniformity of the pulp.

[0064] Pressing and drying: The pressing and drying processes remove moisture from the paper to form a preliminary paper sheet structure.

[0065] Surface treatment: may include coating, calendering, etc. to improve the smoothness and uniformity of the paper.

[0066] Slitting and curling: Slitting the paper into appropriate width and curling it as needed.

[0067] Quality Control: Throughout the production process, the quality and performance of the paper needs to be strictly tested and controlled to ensure that the high standards required for electrolytic capacitor paper are met.

[0068] Special processing: For ultra-thin electrolytic capacitor paper, special production processes may be required, such as using cellulose microfibrils mixed with pulp, and special beating and drying processes to ensure the strength and pressure resistance of the paper.

[0069] Insulation Treatment: In some cases, electrolytic capacitor paper may require insulation treatment to improve its electrical performance.

[0070] The precise control and optimization of these steps are essential for producing high-quality electrolytic capacitor paper. Through these process steps, electrolytic capacitor paper with different properties can be manufactured to meet the needs of different applications. The present invention does not specifically limit the manufacturing process of electrolytic capacitor paper.

[0071] In practical applications, the thickness and tightness of electrolytic capacitor paper have many specific effects on the performance of the capacitor:

[0072] Capacitance: The thickness of electrolytic capacitor paper directly affects the size of the capacitor. Under the same withstand voltage conditions, generally speaking, the thicker the paper, the larger the core size, and the shorter the length of the anode foil that can be wound, resulting in a relatively smaller product capacitance.

[0073] Equivalent Series Resistance (ESR): The material, thickness, and tightness of electrolytic paper will affect its resistance characteristics, which in turn affects the ESR of the capacitor. Thicker paper may result in higher resistance, which will affect the performance of the capacitor at high frequencies. Lower ESR helps improve the power transfer capability and high-frequency response of the capacitor. Electrolytic paper with low tightness usually has lower losses because its structure is looser, which helps the flow of electrolyte and the migration of ions, thereby reducing the equivalent series resistance (ESR) of the capacitor.

[0074] Absorption: The thickness and tightness of electrolytic paper are closely related to its ability to absorb electrolyte. Paper with moderate thickness can better retain electrolyte, thereby improving the performance and stability of the capacitor. At the same time, the lower the tightness of the electrolytic paper, the better its liquid absorption performance and can absorb more electrolyte. This helps the electrolyte fully infiltrate the electrodes, thereby improving the capacitance and conductivity of the capacitor.

[0075] Mechanical strength: Thickness also affects the mechanical strength of electrolytic paper. Thicker papers generally have better tensile strength and pressure resistance, which are critical for the reliability of capacitors under working conditions. In addition, while low-density papers may provide better liquid absorption and lower losses, they may be inferior in mechanical strength. High-density papers can provide better mechanical strength, which is important for the physical stability and durability of capacitors. Further, high-density papers may provide better voltage resistance performance because their structure is more compact and less susceptible to voltage breakdown.

[0076] Thermal stability: The thickness of electrolytic paper has an impact on its thermal stability. In high temperature or high voltage environments, thicker paper may be more resistant to electrochemical reactions and chemical degradation, thereby increasing the service life of the capacitor.

[0077] Leakage current: The thickness and uniformity of electrolytic paper directly affect the leakage current of the capacitor. Paper with uneven thickness or defects may cause increased leakage current, thus affecting the performance and safety of the capacitor. Electrolytic paper with uniform tightness can provide better electrical performance and reduce the risk of short circuits inside the capacitor.

[0078] Therefore, the material, thickness, and tightness of the electrolytic capacitor paper are important factors affecting the performance of the capacitor. Reasonable thickness and tightness design can significantly improve the electrical performance and mechanical stability of the capacitor. The embodiment of the present invention preferably uses a composite electrolytic paper made of wood pulp mixed with Manila hemp fiber. In the embodiment of the present invention, the electrolytic paper is preferably a composite electrolytic paper made of wood pulp mixed with Manila hemp fiber, with a thickness of 30 to 50 μm and a tightness of 0.40 to 0.80 g / cm 3 The electrolytic paper under this condition can reduce the loss angle, self-heating and ESR of the electrolytic capacitor.

[0079] In the winding step of this embodiment, the anode foil, cathode foil, electrolytic paper, and foil guide strip are placed on the riveting and rolling machine in sequence, and the anode aluminum foil and cathode aluminum foil are wound with the electrolytic paper sandwiched between them, and then they are glued with tape or paste to form the capacitor core. It should be noted that the misalignment between the anode foil and the cathode foil, the overlap of the anode foil and the cathode foil relative to the electrolytic paper, the length of the anode foil, the riveting condition of the foil guide strip and the aluminum foil, etc., will greatly affect the final parameter performance and assembly of the capacitor.

[0080] In traditional electrolytic capacitors, the number of foil strips is generally 1 pair, corresponding to the anode and cathode respectively. In the electrolytic capacitor of the present embodiment, the number of pairs of foil strips is 3-8 pairs. This improvement can increase the contact area between the foil strip (the capacity of the aluminum foil) and the aluminum foil (anode foil, cathode foil), reduce product losses and improve the ripple resistance of the product. The optimized design of the foil strip in the embodiment of the present invention helps to disperse the ripple current, reduce the ion blockage and thermal breakdown of the capacitor under the action of the ripple current, and can greatly reduce the breakdown risk at the riveted joints of the foil strip under the ripple current.

[0081] For example, for a large-volume bolt-type capacitor, the number of the foil strips is 3 pairs, 5 pairs, 6 pairs, or 8 pairs.

[0082] In the embodiment of the present invention, the number of rivet points of the single foil guide strip is greater than 6. The number of rivet points of the foil guide strip is increased as much as possible without causing the foil to be easily cracked, thereby increasing the reliability of the connection.

[0083] In other embodiments, the present invention adds a negative foil padding process to the cathode foil to increase the contact area between the conductive foil strip and the cathode foil and improve the ripple current resistance of the product.

[0084] In other embodiments, the present invention adds a paper padding process between the positive foil strip and the negative foil strip to improve the pressure resistance of the riveted joints of the foil strips and reduce the risk of breakdown in later use.

[0085] In other embodiments, the angle between the foil guide strip and the anode foil or cathode foil is 85°≦α≦95°.

[0086] In other embodiments, the distance between the rivet point of the foil guide strip and the edge of the foil guide strip is greater than 1 mm.

[0087] In order to ensure the best performance of the product in the later stage, the anode foil is usually wrapped with electrolytic paper with low density and thick thickness during riveting and coiling, so as to maximize the absorption of electrolyte and better repair oxidation.

[0088] In order to obtain high-performance aluminum electrolytic capacitors, the electrolyte of the embodiment of the present invention needs to be selected from materials with strong ion conductivity, high oxidation efficiency, high flash voltage, and relatively stable and free of impurity ion pollution. For example, the water content of the electrolyte is selected to be ≤2% and the conductivity is ≥1.8ms / cm, and it also has good low-temperature resistance to ensure the performance and reliability of the aluminum electrolytic capacitor, and to ensure the quality and life. Suitable electrolytes include GBL system electrolytes or ethylene glycol system electrolytes. The electrolyte described in this embodiment is preferably a GBL (γ-butyrolactone) system electrolyte. Compared with traditional cyclic carbonate system electrolytes, GBL system electrolytes have better thermal stability and electrochemical properties.

[0089] Generally, the electrolyte of the GBL system includes the following components:

[0090] Solvent: GBL is used as the main solvent and is usually mixed with other solvents (such as carbonates) to improve the performance of the electrolyte. Common solvent combinations include GBL with ethylene carbonate (EC), dimethyl carbonate (DMC), etc. The high dielectric constant and good solubility of GBL make it an ideal solvent for lithium salts.

[0091] Lithium salts: Commonly used lithium salts include lithium hexafluorophosphate (LiPF 6 ) and lithium fluorophosphate (LiFSI). The choice of lithium salt directly affects the conductivity of the electrolyte and the overall performance of the battery. The high donor number of GBL enables it to effectively dissolve LiNO 3 And other additives to enhance the cycle stability of the battery.

[0092] Additives: In order to improve the performance of the electrolyte, some functional additives are usually added, such as film-forming additives and high-temperature stability additives. For example, LiNO 3 It can inhibit the growth of lithium dendrites and enhance the safety and cycle life of the battery. In addition, the selection and dosage of additives need to be optimized according to the specific needs of the battery.

[0093] Ratio: The specific ratio of GBL-based electrolyte varies according to the battery type and application scenario. Generally speaking, the volume ratio of GBL can account for more than 50% of the electrolyte, and the concentration of lithium salt is usually around 1M.

[0094] For the present invention, the electrolyte can be selected from the commercially available GBL system high-voltage series electrolyte, which can satisfy the requirements of the water content of the electrolyte ≤ 2% and the conductivity ≥ 1.8 ms / cm, and has good low-temperature performance.

[0095] In other embodiments of the present invention, the electrolyte may also be a commercially available ethylene glycol electrolyte, as long as the water content of the electrolyte is ≤5% and the conductivity is ≥1.6 ms / cm.

[0096] The present invention does not limit the specific composition of the electrolyte.

[0097] In the drying step of this embodiment, the riveted and rolled core is dried in an oven at 95±5° C. for 2 hours to remove moisture previously adsorbed in the air by the core.

[0098] In the electrolyte impregnation step of the present embodiment, the dried core to be impregnated is transferred to the impregnation cylinder for impregnation as soon as possible; the impregnation parameters are set, and the vacuum degree of the impregnation cylinder is less than -0.09MPa within 300s and the vacuum degree is maintained for impregnation, the pressure in the impregnation cylinder is 0.4MPa, and the impregnation temperature is 60°C. Depending on the size of the product, the core is impregnated in a continuous cycle for 4-6 hours. During impregnation, it is necessary to ensure that the amount of electrolyte adsorbed by the core is moderate. Too much adsorption can easily cause leakage in the later use of the product, and too little adsorption can cause the electrolyte to dry up prematurely when the capacitor is used, thereby shortening the service life of the capacitor and causing premature failure.

[0099] In the assembly and sealing step of this embodiment, the impregnated core is assembled and sealed with the aluminum shell and the cover plate as soon as possible to prevent the core from absorbing moisture. In addition, in the assembly process, after the traditional riveting between the anode foil strip and the cover plate lead-out terminal, a secondary welding is performed by ultrasonic spot welding to reduce the riveting resistance between the foil strip and the cover plate lead-out terminal, improve the current bearing capacity, and prevent the open circuit phenomenon that may occur in the capacitor during use.

[0100] The assembly and sealing step in this embodiment also includes aging and sorting the sealed capacitors, repairing the dielectric oxide film damaged during the manufacturing process to a certain extent, and removing defective products.

[0101] The sorted products are subjected to parameter measurement, casing marking, appearance inspection, packaging and then stored indoors at an ambient temperature of 5-30°C and a humidity of 75%.

[0102] It should be noted that the use and storage environment of electrolytic capacitors have a great impact on the performance of capacitors. During the use of capacitors, the anode is often severely corroded under high temperature load, and the anode foil strip is broken, resulting in the capacitor having no capacity. This is mainly due to the artificial introduction of chloride ions in the production process of raw materials and capacitors, and the residual halogen and impurity ions in the washing water, flux, sealant and other materials used in the PCB circuit board processing of the capacitors in the later stage penetrate into the capacitors and cause corrosion and damage to the products. In addition, the storage environment of the capacitor will also affect its own performance. Therefore, the capacitor needs to be stored indoors for a long time at an ambient temperature of 5-30℃ and a humidity of less than 75%.

[0103] Understandably, the manufacturing process of electrolytic capacitors mainly includes slitting, riveting, impregnation, assembly, aging, sealing, and casing. During the riveting process, attention should be paid to the overlap between the anode foil and the cathode foil and the riveting effect between the foil strip and the aluminum foil, which is the key to the capacity of the capacitor. The impregnation process mainly determines the impregnation effect of the bare core of the capacitor, which affects the subsequent working time of the electrolytic capacitor. The aging process mainly repairs the damaged dielectric oxide film during the manufacturing process to a certain extent and stabilizes the structure of the dielectric film, which can restore the inherent good electrical properties of the capacitor and increase the service life of the product.

[0104] The following examples take the preparation of 35X60 / CD294W / 450V / 820μF / 4.5A electrolytic capacitors with high voltage resistance and large ripple resistance as an example to explore the influence of the optimized design of the number of foil strips and the number of rivet points on product performance.

[0105] The anode foil, cathode foil, electrolytic paper, and electrolyte used in the electrolytic capacitor 1 and the electrolytic capacitor 2 are the same.

[0106] Specifically, the anode foil uses a high forming voltage 640VF foil;

[0107] The cathode aluminum foil adopts 5VF cathode aluminum foil;

[0108] Electrolytic paper is made of composite electrolytic paper made of wood pulp mixed with Manila hemp fiber, with a thickness of 35μm and a density of 0.65g / cm 3 , adopts a four-layer electrolytic paper structure;

[0109] The electrolyte adopts a GBL system high-voltage series electrolyte with a conductivity of ≥1.8ms / cm, a flash voltage of ≥480V, a pH of 5 to 7, and extremely low water content.

[0110] Among them, the foil strips of the electrolytic capacitor 1 are a pair, connected to the anode aluminum foil and the cathode aluminum foil respectively, the number of riveting points of a single foil strip is 12, and the distance between the edge of the riveting point and the edge of the foil strip is greater than 1mm. The angle α between the foil strip and the aluminum foil is 80°.

[0111] The electrolytic capacitor 2 has three pairs of foil strips, which are connected to the anode aluminum foil and the cathode aluminum foil respectively. The number of riveting points of a single foil strip is 16, and the distance between the edge of the riveting point and the edge of the foil strip is greater than 1mm. The angle α between the foil strip and the aluminum foil is 90°.

[0112] The product performance results of electrolytic capacitor 1 and electrolytic capacitor 2 are shown in Table 1.

[0113] Table 1 Product performance results of electrolytic capacitor 1 and electrolytic capacitor 2

[0114]

[0115] It can be seen from the results in Table 1 that increasing the logarithm of the foil strips and the number of rivet points is beneficial to reducing the initial loss value of the product and reducing the change in product parameters after the test.

[0116] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0117] The above is a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for manufacturing a high-performance aluminum electrolytic capacitor, characterized in that: The following steps are involved: Material selection: select corresponding anode foil, cathode foil, electrolytic paper and foil guide strip according to product specifications; Cutting: Cutting the anode foil, cathode foil and electrolytic paper into suitable sizes; Winding: Place the anode foil, cathode foil, electrolytic paper and foil guide strip on the riveting and coiling machine in sequence, and wind and fix them in the structure of anode foil-electrolytic paper-cathode foil to obtain the capacitor core; Drying: drying the capacitor core; Impregnating the electrolyte: placing the dried capacitor core in an impregnation tank containing the electrolyte, so that the capacitor core absorbs a preset amount of electrolyte; Assembly and sealing: The capacitor core containing the electrolyte is sealed with an aluminum shell and a cover plate to obtain a finished product; The number of the foil guide strips of the capacitor core is 3-8 pairs.

2. The method according to claim 1, characterized in that: The included angle between the foil guide strip and the anode foil or cathode foil is 85°≦α≦95°.

3. The method according to claim 1, characterized in that: The number of rivet points of the single foil guide strip is greater than 6.

4. The method according to claim 3, characterized in that: The distance between the riveting point of the foil guide strip and the edge of the foil guide strip is greater than 1 mm.

5. The method according to claim 1, characterized in that: In the slitting step, a tungsten steel knife is used to slit the anode foil and the cathode foil.

6. The method according to claim 1, characterized in that: In the drying step, the drying condition is 95±5° C. for 1 to 3 hours.

7. The method according to claim 1, characterized in that: In the electrolyte impregnation step, the impregnation parameters include making the vacuum degree of the impregnation cylinder less than -0.09 MPa within 300 seconds and maintaining the vacuum degree for impregnation, the pressure in the impregnation cylinder is 0.2-0.6 MPa, and the impregnation temperature is 55-65°C.

8. The method according to claim 7, characterized in that: The immersion time is 4 to 6 hours.

9. A high performance aluminum electrolytic capacitor, characterized in that: The high-performance aluminum electrolytic capacitor is manufactured by the manufacturing method of any one of claims 1 to 8.

10. The high performance aluminum electrolytic capacitor according to claim 9, characterized in that: The storage environment temperature of the high-performance aluminum electrolytic capacitor is 5-30° C. and the humidity is below 75%.

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