Manufacturing method of high-temperature-resistant long-service-life laminated sheet type solid aluminum electrolytic capacitor

Abstract

The invention discloses a manufacturing method of a high-temperature-resistant long-service-life laminated sheet type solid aluminum electrolytic capacitor. The method comprises the steps of cutting an aluminum foil, arranging barrier glue, impregnating a monomer and an oxidizing agent to form a conductive polymer solid electrolyte layer, electrifying and cleaning after polymerization, forming a conductive graphite layer and a conductive silver paste layer, and then sequentially carrying out lamination, injection molding packaging, aging and the like. According to the step of electrifying cleaning after polymerization, forward voltage and reverse voltage are applied to a cleaning tank, and foreign ions wrapped in the deep position of the aluminum foil and the interior of the conductive polymer are thoroughly removed. Through the technical scheme, the leakage current of the laminated solid aluminum electrolytic capacitor can be obviously reduced, the qualification rate of the leakage current is improved, and the thermal stability of the capacitor can be improved, so that the laminated sheet type solid aluminum electrolytic capacitor with high temperature resistance and long service life can be obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of solid aluminum electrolytic capacitors, and in particular relates to a method for manufacturing a high-temperature resistant and long-life laminated chip solid aluminum electrolytic capacitor. Background Art

[0002] In recent years, as the market has put forward higher requirements for the miniaturization, portability, and high availability of smart products, the components in them also need to be continuously improved to meet their lightweight requirements. The same is true for capacitors, which are now increasingly in need of miniaturization. The emergence and development of multilayer solid aluminum electrolytic capacitors are in line with such market demand. Multilayer solid aluminum electrolytic capacitors are a new type of electronic component that uses high molecular conductive polymers as capacitor cathodes. They have a series of characteristics: high frequency and low impedance, excellent temperature and frequency characteristics, and the ability to withstand high ripple currents; because the electrolyte is solid, there will be no leakage or combustion during storage or use, which meets environmental and safety requirements.

[0003] The manufacturing process of laminated solid aluminum electrolytic capacitors in the industry is complex. Especially when the monomer and oxidant are polymerized in the cathode area, many unwanted products will be produced. Even after being washed with pure water, there are still impurities remaining deep in the aluminum foil and inside the conductive polymer. The presence of these impurities will ultimately directly affect the leakage current qualification rate and thermal stability of the laminated capacitor. Therefore, it is an urgent problem for practitioners to develop a manufacturing method that completely removes impurities deep in the aluminum foil and inside the conductive polymer. Summary of the invention

[0004] (1) Technical issues to be resolved

[0005] The purpose of the present invention is to provide a method for manufacturing a high-temperature resistant and long-life laminated chip solid aluminum electrolytic capacitor. Through this technical solution, not only the leakage current of the laminated solid aluminum electrolytic capacitor can be significantly reduced and the leakage current qualification rate can be improved, but also the thermal stability of the capacitor can be improved.

[0006] (2) Technical solution

[0007] In order to solve the above technical problems, the present invention provides a method for manufacturing a high temperature resistant and long life laminated chip solid aluminum electrolytic capacitor, which comprises the following steps:

[0008] (1) Cutting the aluminum foil;

[0009] (2) Coating the cut aluminum foil with barrier glue to divide the cathode area and the anode area;

[0010] (3) forming a conductive polymer cathode layer on the cathode region by a chemical polymerization process;

[0011] (4) Applying voltage to clean the polymerized aluminum foil;

[0012] (5) forming a conductive graphite layer on the outer surface of the conductive polymer cathode layer;

[0013] (6) forming a silver conductive layer on the outer surface of the conductive graphite layer to produce a monolithic capacitor element;

[0014] (7) welding the anode region of the monolithic capacitor element to the anode of the lead frame; bonding the cathode region of the capacitor element to the cathode of the lead frame with a conductive silver paste, and forming a capacitor core after curing;

[0015] (8) Encapsulating the completed laminated capacitor core to form a solid capacitor;

[0016] (9) The capacitor is post-processed such as moisture absorption and aging.

[0017] Preferably, in step (4), the applied voltage is 4 to 20V.

[0018] Preferably, in step (4), the voltage is applied once in the forward direction and once in the reverse direction.

[0019] Preferably, in step (4), the voltage is applied for a period of 20 minutes to 2 hours.

[0020] Preferably, in step (4), the number of cleaning times is 4 to 10 times. Beneficial Effects

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The manufacturing method of the solid aluminum electrolytic capacitor of the present invention adopts post-polymerization electric cleaning, that is, after the monomer and the oxidant generate the conductive polymer, a forward voltage and a reverse voltage are applied to both ends of the cleaning tank, so that under the action of the electric field, the impurity ions deep in the aluminum foil and inside the conductive polymer (mainly sulfate ions generated by the oxidant and the polymerization reaction, and a small amount of Fe3+ ions, etc.) will move to the positive and negative electrodes, and at the same time, they are slowly removed by multiple flowing pure water cleaning methods. This technical solution can not only significantly reduce the leakage current of the laminated solid aluminum electrolytic capacitor, improve the leakage current qualification rate, but also improve the thermal stability of the capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for describing the specific implementation methods or the prior art will be briefly introduced below. Obviously, the drawings described below are only simple schematic diagrams of the cleaning device of the present invention and manufacturing process flow charts. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 The present invention is a simple schematic diagram of a cleaning device for a high-temperature-resistant and long-life laminated chip solid aluminum electrolytic capacitor according to an embodiment of the present invention.

[0025] Figure 2 The present invention is a manufacturing process flow chart of a high temperature resistant and long life laminated chip solid aluminum electrolytic capacitor.

[0026] The markings in the attached figure are: 1-aluminum foil element after monomer polymerization, 2A / 2B-conductive electrode plate, 3-water inlet, 4-water outlet. DETAILED DESCRIPTION

[0027] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the technical scheme in the specific implementation mode of the present invention is clearly and completely described below to further illustrate the present invention. Obviously, the specific implementation mode described is only a part of the implementation mode of the present invention, rather than all styles.

[0028] Example 1.

[0029] Here are the steps:

[0030] (1) Select 12VF aluminum foil for cutting, the width is 3.5mm and the length is 13mm;

[0031] (2) coating a barrier adhesive on the surface of the selected chemically formed aluminum foil, wherein the barrier adhesive divides the chemically formed aluminum foil into a cathode region and an anode region, wherein the cathode region has a height of 4.7 mm and the adhesive line has a width of 0.7 mm;

[0032] (3) The cathode area of ​​the pretreated aluminum foil is immersed in a monomer reduction solution (EDOT), taken out and dried, then immersed in an oxidation solution (ammonium persulfate), and then taken out and dried. The above operation is repeated 18 times to form a conductive polymer layer on the surface of the formed foil;

[0033] (4) Apply a forward voltage of 6.3 V to both ends of the cleaning tank for 30 minutes, then apply a reverse voltage of 6.3 V for 30 minutes, the water tank temperature is 60°C, clean with flowing pure water, and then cycle 6 times;

[0034] (5) Immerse the chemically polymerized aluminum foil in graphite slurry for 60 seconds, slowly pull it out, and then dry it;

[0035] (6) Immerse the graphite-cured aluminum foil in the silver paste for 120 seconds, slowly pull it out, and then dry it;

[0036] (7) The anode area of ​​the capacitor element obtained by curing the silver layer is welded to the anode of the lead frame, and the cathode area of ​​the capacitor element is adhered to the cathode of the lead frame with a conductive silver paste. After the silver paste is cured, the capacitor elements are stacked together to form a capacitor core, with a total of 6 layers;

[0037] (8) Place the completed laminated core in the mold cavity, inject epoxy resin by heating and pressurizing, and maintain for 120 seconds to complete the encapsulation. Thus, a capacitor is formed;

[0038] (9) The packaged capacitors are placed in an environment with a temperature of 60°C and a humidity of 95% to absorb moisture for 12 hours; then aged at a voltage of 7.6V for 2 hours, and qualified products are screened out.

[0039] Example 2

[0040] The difference from Example 1 is that in step (4), a forward voltage of 8 V is applied for 50 min, and then a reverse voltage of 8 V is applied for 50 min, and then the cycle is repeated 7 times.

[0041] Example 3

[0042] The difference from Example 1 is that in step (3), a forward voltage of 10 V is applied for 60 min, and then a reverse voltage of 10 V is applied for 60 min, and then the cycle is repeated 8 times.

[0043] Example 4

[0044] The difference from Example 1 is that in step (3), a forward voltage of 12 V is applied for 80 min, and then a reverse voltage of 12 V is applied for 80 min, and then the cycle is repeated 10 times.

[0045] Comparative Example 1

[0046] The difference from Example 1 is that step (4) is eliminated.

[0047] Comparative Example 2

[0048] The difference from Example 1 is that the voltage applied in step (4) is 2V.

[0049] Comparative Example 3

[0050] The difference from Example 1 is that in step (4), only a forward voltage of 6.3 V is applied and the cleaning time is 60 min.

[0051] Comparative Example 4

[0052] The difference from Example 1 is that in step (4), only a reverse voltage of 6.3 V is applied and the cleaning time is 60 min.

[0053] Comparative Example 5

[0054] The difference from Example 1 is that the electric cleaning time in step (4) is 10 minutes for the forward voltage and 10 minutes for the reverse voltage.

[0055] Comparative Example 6

[0056] The difference from Example 1 is that the number of cycles in step (4) is 2 times.

[0057] The above-mentioned embodiments 1-4 are manufactured into 6.3V 150uF capacitors.

[0058] In order to verify the advantages of the capacitors made by the manufacturing method of the present invention, an application was made to test the relevant parameters of the capacitors manufactured by the above embodiments and corresponding comparative examples. The number was 32. The initial characteristic test was 120Hz to test the capacitance and loss, 100KHz to test the ESR, and the capacitors with a leakage current value of 37.8µA (0.04CV) or more after applying the rated voltage for 1 minute were regarded as defective products. The heat resistance test was to apply the rated voltage while testing at 125℃ / 3000h, and then the capacitors with a leakage current value of 37.8µA (0.04CV) or more after applying the rated voltage for 1 minute were regarded as defective products. The specific test results are shown in the table below.

[0059] Table 1 Test results of various embodiments and comparative examples:

[0060]

[0061] Table 2 Test results of various embodiments and comparative examples:

[0062]

[0063] As can be seen from Tables 1 and 2, compared with the capacitors prepared in Comparative Example 1, the capacitors prepared in the embodiments of the manufacturing method of the present invention can improve the leakage current qualification rate of the capacitors by electro-cleaning after polymerization, and can also improve the heat resistance stability of the capacitors.

[0064] It can be seen from Tables 1 and 2 that, compared with the capacitors prepared by Comparative Examples 2, 5, and 6, the capacitors prepared by the various embodiments of the manufacturing method of the present invention have too low applied voltage during cleaning, too short cleaning time, and insufficient number of cycles, and cannot completely remove the impurity ions, so the leakage current defect rate and thermal stability are not good.

[0065] It can be seen from Tables 1 and 2 that, compared with the capacitors prepared by comparative examples 3 and 4, when the voltage is applied in one direction during cleaning, since both sides of the aluminum foil are covered with conductive polymers, it is difficult to completely remove the impurity ions deep in the aluminum foil, and thus the leakage current defect rate and thermal stability are not good.

[0066] In summary, the manufacturing method of the high temperature resistant and long life laminated chip solid aluminum electrolytic capacitor provided by the present invention can significantly reduce the leakage current of the laminated solid aluminum electrolytic capacitor, improve the leakage current pass rate, and improve the thermal stability of the capacitor.

[0067] The above describes the specific embodiments of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary specific embodiments, and the present invention can be implemented in other specific forms without departing from the concept or basic characteristics of the present invention. Therefore, no matter from which point of view, the above specific embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention.

[0068] In addition, it should be understood that although the present specification is described according to various implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation method may also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A method for manufacturing a high temperature resistant and long life laminated solid aluminum electrolytic capacitor, characterized in that The following steps are involved: Step 1: Cut the aluminum foil; Step 2: Coat the cut aluminum foil with barrier glue to divide the cathode area and the anode area; Step 3: forming a conductive polymer cathode layer on the cathode region by a chemical polymerization process; Step 4: Apply voltage to clean the polymerized aluminum foil; Step 5: forming a conductive graphite layer on the outer surface of the conductive polymer cathode layer; Step 6: forming a conductive silver layer on the outer surface of the conductive graphite layer to form a monolithic capacitor element; Step 7: welding the anode region of the monolithic capacitor element to the anode of the lead frame; The cathode area of ​​the capacitor element is bonded to the cathode of the lead frame with a conductive silver paste, and after curing, the capacitor core is formed; Step 8: Encapsulating the completed laminated capacitor core to form a solid capacitor; Step 9: Perform post-processing such as moisture absorption and aging on the capacitor.

2. The method for manufacturing a high temperature resistant and long life laminated solid aluminum electrolytic capacitor according to claim 1, characterized in that: In the step (4), the applied voltage is 4 to 20V.

3. The method for manufacturing a high temperature resistant and long life laminated solid aluminum electrolytic capacitor according to claim 1, characterized in that: In the step (4), the voltage is applied once in the forward direction and once in the reverse direction.

4. The method for manufacturing a high temperature resistant and long life laminated solid aluminum electrolytic capacitor according to claim 1, characterized in that: In the step (4), the voltage is applied for a period of 20 minutes to 2 hours.

5. The method for manufacturing a high temperature resistant and long life laminated solid aluminum electrolytic capacitor according to claim 1, characterized in that: In the step (4), the cleaning frequency is 4 to 10 times.

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