Manufacturing method of novel laminated aluminum capacitor

Abstract

The invention discloses a method for manufacturing a novel laminated aluminum capacitor, which comprises the following steps of: coating a graphite layer on a single chip core, stacking, connecting a cathode by bonding silver paste, and integrally coating a silver layer. The method solves the problems of large thickness, high cost and low stacking qualification rate of the silver paste layer in the prior art, can increase the number of stacking layers, improves the capacity, reduces the consumption of the silver paste, shortens the production cycle, and improves the consistency and reliability of products.

Description

Technical Field

[0001] The invention belongs to the technical field of capacitors, and in particular relates to a manufacturing method of a novel laminated aluminum capacitor. Background Art

[0002] In the existing production of solid electrolyte chip-type laminated aluminum electrolytic capacitors, the process includes cutting the formed aluminum foil and welding it to the steel bar, coating it with isolation glue, and then forming it. Then, a conductive polymer is prepared in the negative electrode area as the cathode electrolyte. Subsequently, a graphite layer and a silver paste layer are coated on its surface to lead out the cathode. Then, the cores are stacked and electrically connected by welding and bonding silver paste. Finally, the finished product is obtained by plastic sealing, aging and screening.

[0003] However, the existing technology for stacking capacitor cores coated with graphite and silver paste has obvious shortcomings: first, the thickness of the silver paste layer accounts for 20%-40% of the thickness of the single-piece aluminum core, reducing the space utilization of the stacked aluminum capacitor and limiting its performance; second, the physical properties of the silver paste can easily lead to a 5-30μm difference in the thickness of the single-piece core, which reduces the qualified rate of the stacking process; third, the cathode of the single-piece capacitor core is coated with graphite silver paste to lead out the cathode, which consumes a large amount of conductive silver paste, resulting in high production costs.

[0004] Chinese utility model patent publication number CN113990664B discloses a method for manufacturing multilayer solid-state aluminum electrolytic capacitors. This method uses a process that involves impregnation with silver paste, followed by decompression and drying to form a conductive silver layer. This reduces the thickness of the single aluminum foil and the thickness of the laminated core. This method not only reduces silver costs and core thickness, but also enables the multilayer aluminum electrolytic capacitor to exhibit excellent ESR performance. Summary of the Invention

[0005] In order to solve the above problems, the present invention aims to provide a novel method for manufacturing a laminated aluminum capacitor.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: a method for manufacturing a novel laminated aluminum capacitor, comprising the following steps:

[0007] Step 1: preparing a monolithic capacitor core, the capacitor core being coated with graphite;

[0008] Step 2: stacking the monolithic capacitor cores, and coating the entire stacked cores with silver paste. The methods of coating the silver paste include but are not limited to dipping, roller coating, spin coating, printing or sputtering;

[0009] Step 3: Plastic seal the stacked cores.

[0010] Furthermore, the step 1 is as follows:

[0011] Step 11: Cut the aluminum foil into specified sizes and weld it to the steel bar;

[0012] Step 12: Apply isolation glue to the fixed position of the cut aluminum foil;

[0013] Step 13: Immerse the product coated with the isolation glue into the chemical solution for chemical formation;

[0014] Step 14: Continue to apply isolation glue to the corresponding positions of the aluminum foil to separate the positive and negative areas of the product;

[0015] Step 15: forming a conductive polymer cathode layer on the cathode region by chemical polymerization;

[0016] Step 16: Cover the outer surface of the conductive polymer cathode layer with a graphite layer to lead out the capacitor cathode.

[0017] Furthermore, the product of the polymer cathode layer is a cathode electrolyte, and the cathode electrolyte preparation method includes but is not limited to chemical polymerization, electrochemical polymerization or the use of one or more combinations of pre-polymerized conductive polymer slurry.

[0018] Furthermore, the aluminum foil is an anodized aluminum foil with a forming voltage of 3V-200V and a specific capacitance of 2μF / cm^2-600μF / cm^2.

[0019] Furthermore, the step 2 is specifically as follows:

[0020] Step 22: Stacking the graphite-coated capacitor cores;

[0021] Step 23: The positive electrode of the capacitor core is electrically connected to the lead wire by resistance welding or laser welding;

[0022] Step 24: The cathode portion is bonded with conductive silver paste and a certain temperature and pressure are applied to form an electrical connection.

[0023] Furthermore, in step 24, the temperature is 60°C-220°C, and the pressure is 0.1kgf / cm^2-30kgf / cm^2

[0024] Furthermore, the step 3 specifically includes encapsulating the stacked cores with epoxy resin to protect the capacitor, and then obtaining the finished conductive polymer solid chip aluminum electrolytic capacitor by aging and screening the semi-finished product.

[0025] Furthermore, the capacitor cathode is a solid polymer, and may also be any solid cathode material, including but not limited to manganese dioxide.

[0026] Furthermore, the capacitor is any capacitor that requires the use of conductive ink to lead out the cathode and stacking and bonding processes, including but not limited to laminated aluminum capacitors, polymer tantalum capacitors and polymer niobium capacitors.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. Increased Capacity and Enhanced Reliability: Eliminating the need for silver coating on monolithic capacitor cores reduces the thickness of each core by 20%-40%. Within a fixed size, the number of stackable capacitor core layers increases by 20%-40%, correspondingly increasing capacity. Furthermore, using the same number of stacked layers and aluminum foil specifications, this method produces a thicker cathode layer, enhancing the cathode polymer's ability to wrap around the aluminum foil and improving the core's stress resistance, thereby increasing product yield and reliability.

[0029] 2. Cost reduction: The present invention coats the entire core with silver paste after stacking, significantly reducing the amount of silver paste used and lowering costs. Furthermore, the number of silver paste coatings is reduced, shortening the production cycle and reducing time costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 It is the basic structure of the existing multilayer aluminum capacitor;

[0032] Figure 2 Schematic diagram of coating graphite and silver layers on a monolithic core in the prior art;

[0033] Figure 3 This is a schematic diagram of a monolithic core coated only with graphite in the present invention;

[0034] Figure 4 A schematic diagram of a capacitor prepared by the novel multilayer aluminum capacitor manufacturing method of the present invention;

[0035] 1-positive electrode lead; 2-negative electrode lead; 3-epoxy resin; 4-formed aluminum foil; 5-polymer; 6-carbon layer; 7-silver layer; 8-cathode layer; DETAILED DESCRIPTION

[0036] The present invention is further described below with reference to the accompanying drawings and specific embodiments. However, it should not be understood that the scope of the subject matter described in the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various modifications, substitutions and changes made according to common technical knowledge and customary means in the field are included in the scope of the present invention.

[0037] Reference Figure 1 , which is the basic structure of the laminated aluminum capacitor made by the existing technology, Figure 1 The left picture shows the complete structure of a laminated aluminum capacitor, and the right picture shows the schematic diagram of a single-piece aluminum capacitor core. It includes a positive lead 1, a negative lead 2, epoxy resin 3, chemically formed aluminum foil 4, polymer 5, the first carbon layer 6, and the second silver layer 7. Figure 2 , a graphite layer is made on the monolithic core and then a silver layer is made.

[0038] The general production process of solid electrolyte chip-type laminated aluminum electrolytic capacitors is as follows:

[0039] 1) Cut the aluminum foil into the specified size and weld it to the steel bar;

[0040] 2) Apply isolation glue to the fixed position of the cut aluminum foil;

[0041] 3) Immerse the product coated with the isolation adhesive into the chemical forming solution for further chemical forming;

[0042] 4) Apply isolation glue at certain positions on the aluminum foil to separate the positive and negative areas of the product;

[0043] 5) Preparing a conductive polymer in the negative electrode area of the product as the cathode electrolyte of the product;

[0044] 6) A graphite layer is applied to the surface of the conductive polymer cathode polymer layer to introduce the polymer cathode and reduce the product's equivalent series resistance. A highly conductive silver paste layer is then applied to the graphite layer to reduce the product's equivalent series resistance and stress tolerance. By coating the conductive polymer with graphite and silver paste to introduce the capacitor cathode, a monolithic capacitor core is now complete.

[0045] 7) According to the capacity design requirements of the product, the capacitor cores coated with graphite and silver paste are stacked;

[0046] 8) The stacked cores are plastic-sealed to protect the capacitors, and the semi-finished products are then smelted and screened to obtain finished conductive polymer solid chip aluminum electrolytic capacitors.

[0047] The above existing solutions coat the polymer cathode with graphite silver paste to enhance cathode conductivity, reduce the equivalent series resistance of the capacitor, and lead out the cathode layer of the capacitor core. The graphite layer thickness is typically 10-50μm, and the silver paste layer thickness is typically 20-100μm. The thickness of the monolithic aluminum core is typically 180μm-250μm. The silver paste layer thickness generally accounts for 20%-40% of the thickness of the monolithic aluminum core. The silver paste layer reduces the space utilization of the laminated aluminum capacitor and is a key factor limiting the performance of the laminated aluminum capacitor. At the same time, when coating the silver paste, due to the viscosity, sagging, and thixotropic properties of the silver paste material, the silver paste easily accumulates at the bottom of the core, resulting in a thickness difference of 5-30μm in the monolithic core. Excessive thickness differences in the monolithic core will lead to a decrease in the qualified rate of the stacking process. In addition, coating the cathode of the monolithic capacitor core with graphite silver paste to lead out the cathode consumes a large amount of conductive silver paste, resulting in high production costs.

[0048] The present invention provides a new method for manufacturing a laminated aluminum capacitor, which can manufacture capacitors with larger capacity while reducing material costs and production cycles and improving product consistency.

[0049] The solution of the present invention is not to coat the monolithic capacitor core with silver paste, but only to coat it with graphite, then stack the monolithic capacitor cores coated with graphite by welding the positive electrodes and bonding the negative electrodes with conductive silver paste, and then immerse the entire stacked core in silver paste. Figure 3 and Figure 4 After stacking, the cathode area is bonded together piece by piece using conductive silver paste and then bonded to the lead wire to lead out the cathode. After stacking, the whole is coated with silver paste. The core is then packaged to form a capacitor. The packaging can be metal shell packaging, epoxy resin packaging, soft packaging and other capacitor packaging forms.

[0050] In the prior art, each aluminum capacitor core is coated with graphite silver paste. In the present invention, only each aluminum capacitor core is coated with graphite. The graphite-coated capacitor cores are then stacked according to the product's capacity design requirements. During the stacking process, the positive electrode of the capacitor core is electrically connected to the lead frame through resistance welding or laser welding, and the cathode is bonded with highly conductive silver paste and a certain temperature and pressure are applied to form an electrical connection.

[0051] The stacked core cathode is coated with a layer of silver by dipping, rolling, spin coating, printing or sputtering to improve the cathode conductivity of the core and reduce the equivalent series resistance of the product.

[0052] In summary, the present invention does not coat a silver layer on a single-piece capacitor core, and the thickness of each capacitor core is reduced by 20%-40%. Under a fixed specification and size, the number of capacitor core layers that can be stacked increases by 20%-40%, and the capacity is therefore increased by 20-40%. At the same time, while ensuring the same capacity, a higher number of stacked layers means that aluminum foil with a higher withstand voltage but a lower specific capacitance can be selected. A higher withstand voltage will improve the reliability of the stacked aluminum capacitor and give it a longer life. At the same time, if the same number of stacked layers and the same specification of aluminum foil are used, the present invention can produce a thicker cathode layer. A thicker cathode layer can increase the reliability of the stacked aluminum capacitor and the product qualification rate.

[0053] A novel method for manufacturing a laminated aluminum capacitor comprises the following steps:

[0054] Step 11: Cut the aluminum foil into specified sizes and weld it to the steel bar;

[0055] Step 12: Apply isolation glue to the fixed position of the cut aluminum foil;

[0056] Step 13: Immerse the product coated with the isolation glue into the chemical solution for chemical formation;

[0057] Step 14: Continue to apply isolation glue to the corresponding positions of the aluminum foil to separate the positive and negative areas of the product;

[0058] Step 15: forming a conductive polymer cathode layer on the cathode region by chemical polymerization;

[0059] Step 16: Cover the outer surface of the conductive polymer cathode layer with a graphite layer to lead out the capacitor cathode.

[0060] Step 22: Stacking the graphite-coated capacitor cores;

[0061] Step 23: The positive electrode of the capacitor core is electrically connected to the lead frame by resistance welding or laser welding;

[0062] Step 24: The cathode portion is electrically connected by applying a highly conductive silver paste and a certain temperature and pressure.

[0063] Step 25: The cathode of the stacked capacitor core is entirely coated with silver paste to reduce the equivalent series resistance of the capacitor and protect the capacitor core, thereby improving the stress resistance of the core.

[0064] Step 3: Plastic-sealing the stacked cores, plastic-sealing the stacked cores with epoxy resin to protect the capacitor, and then aging and screening the semi-finished products to obtain finished conductive polymer solid chip aluminum electrolytic capacitors.

[0065] Implementation 1 and Example 2: As shown in Table 1, under the same shell size, if the prior art solution has a stacking specification of 12 layers and a single core thickness of 250μm, the size after stacking is 2.75mm. If the solution of the present invention is used, the single core thickness is about 180μm, and the thickness is about 2.70mm when stacked in 15 layers. After stacking, the silver paste is coated, and the silver paste thickness is about 40μm. Then, the core thickness after stacking 15 layers using the solution of the present invention is 2.74mm. As shown in Table 1, Example 1, if the solution of the present invention and the prior art use the same specifications of aluminum foil, the capacity of the solution of the present invention can be increased by 80 / 220=36.3%. At the same time, because the height difference between the positive and negative poles of the monolithic capacitor core made by the solution of the present invention is small, the stacking pass rate is higher, and the pass rate of the solution of the present invention is higher. As shown in Example 2 of Table 1, if the present invention and the prior art employ the same capacity design, the present invention allows the use of aluminum foil with a higher forming voltage. The aluminum foil forming voltage is increased by 8 / 28 = 28.5%. While maintaining the same capacitor specifications, increasing the aluminum foil forming voltage can improve the capacitor's production yield and reliability. While maintaining the same capacitor reliability, increasing the aluminum foil forming voltage can increase the capacitor's rated voltage, enabling its use in higher voltage scenarios.

[0066] Table 1 Comparison of technical effects of the present invention and prior art

[0067]

[0068] Example 3. As shown in Table 2, if the present invention and the prior art use the same number of stacked layers and the same aluminum foil specifications, the present invention can make the cathode polymer layer thicker. A thicker cathode layer can improve the coating of the cathode polymer on the aluminum foil, improve the stress resistance of the core, and improve the product qualification rate and reliability.

[0069] Table 2 Comparison of technical effects of the present invention and prior art

[0070]

[0071]

[0072] As shown in Table 3, using the existing technology, coating a single core of a rack of 3,300 capacitors consumes 40 to 80 grams of silver paste. If stacked in 11 layers, this produces approximately 300 capacitors. However, using the present invention, coating 300 stacked cores with silver paste consumes only 15 to 30 grams. This reduces silver paste costs by at least 40%.

[0073] Table 3 Comparison of material costs between the present invention and the prior art

[0074]

[0075] The present invention does not coat silver paste on a single-chip capacitor core, but coats the entire stacked core with silver paste, reducing the number of silver paste coatings. For example, in the prior art, coating silver paste on 10 racks of 3,300 single-chip capacitor cores per rack takes about 2 to 3 hours. However, with the present invention, coating silver paste on a rack of 3,000 stacked cores only takes about 1 to 2 hours, shortening the production cycle and reducing time costs. The specific efficiency savings are shown in Table 4.

[0076] Table 4 Comparison of time costs between the present invention and the prior art

[0077]

[0078] The conductive paste used in the present invention to draw out the cathode layer is conductive graphite and conductive silver paste, but is not limited to conductive graphite and conductive silver paste. Any conductive ink that can achieve the same effect is included, including but not limited to any conductive ink using carbon nanotubes, conductive polymers, and conductive metal particles as fillers. The capacitor used in the present invention is not only a stacked aluminum capacitor, but can also be any capacitor that requires a conductive ink to draw out the cathode and stack and bond processes, such as polymer tantalum capacitors and polymer niobium capacitors. The capacitor cathode used in the present invention is a solid polymer, and can also be any solid cathode material, such as manganese dioxide.

[0079] The above describes in detail the manufacturing method of a novel multilayer aluminum capacitor provided by the present invention. Specific examples are used herein to illustrate the structure and operating principles of the present invention. The description of the above embodiments is intended only to facilitate understanding of the method and core concepts of the present invention. It should be noted that those skilled in the art will be able to make various improvements and modifications to the present invention without departing from the principles of the present invention, and such improvements and modifications fall within the scope of protection of the claims.

Claims

1. A novel method for manufacturing a laminated aluminum capacitor, characterized in that: The following steps are included: Step 1: preparing a monolithic capacitor core, the capacitor core being coated with graphite; Step 2: stacking the monolithic capacitor cores, and coating the entire stacked cores with silver paste. The methods of coating the silver paste include but are not limited to dipping, roller coating, spin coating, printing or sputtering; Step 3: Plastic seal the stacked cores.

2. The method for manufacturing the novel multilayer aluminum capacitor according to claim 1, wherein: The specific steps in step 1 are as follows: Step 11: Cut the aluminum foil into specified sizes and weld it to the steel bar; Step 12: Apply isolation glue to the fixed position of the cut aluminum foil; Step 13: Immerse the product coated with the isolation glue into the chemical solution for chemical formation; Step 14: Continue to apply isolation glue to the corresponding positions of the aluminum foil to separate the positive and negative areas of the product; Step 15: forming a conductive polymer cathode layer on the cathode region by chemical polymerization; Step 16: Cover the outer surface of the conductive polymer cathode layer with a graphite layer to lead out the capacitor cathode.

3. The method for manufacturing the novel multilayer aluminum capacitor according to claim 2, wherein: The product of the polymer cathode layer is a cathode electrolyte, and the cathode electrolyte preparation method includes but is not limited to chemical polymerization, electrochemical polymerization or the use of one or more combinations of pre-polymerized conductive polymer slurry.

4. The method for manufacturing a novel multilayer aluminum capacitor according to claim 2, wherein: The aluminum foil is an anodic aluminum foil with a forming voltage of 3V-200V and a specific capacitance of 2μF / cm^2-600μF / cm^2.

5. The method for manufacturing the novel multilayer aluminum capacitor according to claim 1, wherein: The step 2 is specifically as follows: Step 22: Stacking the graphite-coated capacitor cores; Step 23: The positive electrode of the capacitor core is electrically connected to the lead wire by resistance welding or laser welding; Step 24: The cathode portion is bonded with conductive silver paste and a certain temperature and pressure are applied to form an electrical connection. Step 25: The cathode of the stacked capacitor core is entirely coated with silver paste to reduce the equivalent series resistance of the capacitor and protect the capacitor core, thereby improving the core's stress resistance.

6. The method for manufacturing the novel multilayer aluminum capacitor according to claim 3, wherein: In step 24, the temperature is 60° C.-220° C., and the pressure is 0.1 kgf / cm^2-30 kgf / cm^2.

7. The method for manufacturing the novel multilayer aluminum capacitor according to claim 1, wherein: The step 3 specifically includes encapsulating the stacked cores with epoxy resin to protect the capacitor, and then obtaining a finished conductive polymer solid chip aluminum electrolytic capacitor by aging and screening the semi-finished product.

8. The method for manufacturing the novel multilayer aluminum capacitor according to claim 1, wherein: The capacitor cathode is a solid polymer, and can also be any solid cathode material, including but not limited to manganese dioxide.

9. The method for manufacturing a novel multilayer aluminum capacitor according to claim 1, wherein: The capacitor is any capacitor that requires conductive ink to lead out the cathode layer and stacking and bonding process, including but not limited to stacked aluminum capacitors, polymer tantalum capacitors and polymer niobium capacitors.

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