High temperature multilayer film capacitor and preparation method thereof

Abstract

The present invention discloses a high-temperature laminated film capacitor and its preparation method. The capacitor comprises: a substrate, an inner core, terminal electrodes, and an encapsulation layer. The inner core comprises at least three dielectric layers and at least two inner electrode layers, with the dielectric layers and the inner electrode layers alternately stacked. The dielectric layer at the bottom of the inner core is disposed on the substrate, while the dielectric layer at the top of the inner core comprises a soluble high-temperature polymer. The terminal electrodes comprise a first terminal electrode and a second terminal electrode, with the first terminal electrode disposed on one side of the substrate and connected to at least one inner electrode layer, and the second terminal electrode disposed on the other side of the substrate and connected to the remaining inner electrode layers. The encapsulation layer encapsulates the substrate, inner core, and terminal electrodes, with the ends of the first and second terminal electrodes remaining unencapsulated. The high-temperature laminated film capacitor exhibits good reliability at temperatures not less than 150°C.

Description

Technical Field

[0001] The present invention belongs to the technical field of capacitors, and in particular relates to a high-temperature laminated film capacitor and a preparation method thereof. Background Art

[0002] Dielectric film capacitors have an intrinsically fast charge and discharge rate and ultra-high power density. They are an extremely important type of power-type energy storage device and play a key role in high-power energy storage and pulse power systems such as grid frequency modulation, new energy grid connection, and electric vehicles. Organic film capacitors are widely used in industries such as electric vehicles, wind power, photovoltaics, lighting, and railway locomotives due to their many advantages such as light weight, low cost, easy large-area preparation, high dielectric strength, unique self-healing properties, no liquid medium, and easy integration of polymer dielectrics. In recent years, oil and gas exploration, electric vehicles and other fields have a significant and urgent need for high-temperature (≥150°C) high-energy storage density electrostatic capacitors. Driven by these demands, electrostatic capacitors are showing a development trend of high temperature, thin layer, and high voltage resistance.

[0003] Film capacitors have two component structures: wound and stacked. Compared with traditional wound film capacitors, multilayer polymer film capacitors (MLPCs) meet the requirements of the development of the information industry and have many advantages, such as small size, good dimensional consistency, low inductance and equivalent series resistance, good interlayer consistency (no internal stress), excellent long-term use, strong anti-interference ability and pulse current resistance, and suitability for large-scale production. The current stacking process mainly includes: (1) winding (winding the metallized film on a long core strip); (2) gold spraying; (3) heat setting; (4) slicing (cutting the stacked components from the core strip); (5) welding the terminal electrodes and adding leads; (6) packaging; (7) testing and inspection. At present, high-temperature (~125℃) polyester-based multilayer capacitors all use the above-mentioned preparation process. Recently, SABIC reported a new product based on polyetherimide (ULTEM TM However, there are few reports on the use of MLPC at high temperatures (≥150°C), and a new preparation process is urgently needed to be developed. Summary of the Invention

[0004] The present invention aims to at least partially address one of the technical problems in the related art. To this end, one object of the present invention is to provide a high-temperature multilayer film capacitor and a method for manufacturing the same. The high-temperature multilayer film capacitor exhibits good reliability at temperatures not less than 150°C.

[0005] In one aspect of the present invention, a high-temperature multilayer film capacitor is provided. According to an embodiment of the present invention, the high-temperature multilayer film capacitor comprises:

[0006] substrate;

[0007] an inner core, the inner core comprising at least three dielectric layers and at least two inner electrode layers, the dielectric layers and the inner electrode layers being alternately stacked, the dielectric layer at the bottom being disposed on the substrate, the dielectric layer at the top being a soluble high-temperature polymer;

[0008] terminal electrodes, the terminal electrodes comprising a first terminal electrode and a second terminal electrode, the first terminal electrode being provided on one side of the substrate and connected to the at least one internal electrode layer, the second terminal electrode being provided on the other side of the substrate and connected to the remaining internal electrode layers;

[0009] The encapsulation layer encapsulates the substrate, the inner core and the terminal electrodes, and ends of the first terminal electrode and the second terminal electrode are not encapsulated.

[0010] According to the above embodiment of the present invention, a high-temperature stacked film capacitor is provided on a substrate, wherein an inner core including at least three dielectric layers and at least two inner electrode layers is provided, and the dielectric layers and the inner electrode layers are alternately stacked. The dielectric layer at the bottom of the inner core is provided on the substrate, and the uppermost end of the inner core is a dielectric layer. At the same time, a first terminal electrode and a second terminal electrode are provided on both sides of the substrate, respectively. The first terminal electrode is connected to at least one inner electrode layer, and the second terminal electrode is connected to the remaining inner electrode layers. Finally, an encapsulation layer is formed on the substrate, the inner core and the terminal electrodes, and the ends of the first terminal electrode and the second terminal electrode are not encapsulated. The dielectric layer includes a soluble high-temperature polymer having a high glass transition temperature and a wide band gap, so that the capacitor of the present application has great application potential in the field of high-temperature energy storage and can significantly improve the breakdown field strength of the dielectric system. As a result, the capacitor of the present application has good reliability at high temperatures of not less than 150°C.

[0011] In addition, the high-temperature multilayer film capacitor according to the above embodiment of the present invention may also have the following additional technical features:

[0012] In some embodiments of the present invention, the thickness of the substrate is not less than 5 μm.

[0013] In some embodiments of the present invention, the inner electrode layer is a metal foil layer or a metallized electrode.

[0014] In some embodiments of the present invention, the thickness of a single dielectric layer is 1-10 μm.

[0015] In some embodiments of the present invention, the glass transition temperature of the soluble high temperature polymer is not less than 150°C.

[0016] In some embodiments of the present invention, the inner core includes at least three inner electrode layers, the first end electrode is connected to the spaced inner electrode layers, one inner electrode layer is located between the spaced inner electrode layers, and the second end electrode is connected to the remaining inner electrode layers. This can increase the capacitance of the capacitor.

[0017] In some embodiments of the present invention, one of the two adjacent inner electrode layers extends out of the edge of the dielectric layer in a first direction, and the other extends out of the edge of the dielectric layer in an opposite direction, thereby facilitating connection between the inner electrode layers and the terminal electrodes.

[0018] In another aspect, the present invention provides a method for preparing the above-mentioned high-temperature multilayer film capacitor. According to an embodiment of the present invention, the method includes:

[0019] (1) mixing a soluble high-temperature polymer with a solvent to obtain a spraying liquid, ultrasonically atomizing the mixture and spraying the mixture onto a substrate, followed by heat treatment to form a dielectric layer on the substrate;

[0020] (2) forming an internal electrode layer on the dielectric layer;

[0021] (3) ultrasonically atomizing the spraying liquid and spraying it on the inner electrode layer, followed by heat treatment;

[0022] (4) repeating steps (2) and (3) to alternately stack at least three dielectric layers and at least two inner electrode layers on the substrate, with the uppermost end of the inner core being the dielectric layer, and then performing hot pressing and shaping;

[0023] (5) disposing a first terminal electrode on one side of the substrate and connected to the at least one internal electrode layer, and disposing a second terminal electrode on the other side of the substrate and connected to the remaining internal electrode layers;

[0024] (6) Encapsulating the device obtained in step (5) to obtain a high-temperature multilayer film capacitor.

[0025] According to the method of the above embodiment of the present invention, an ultrasonic spraying process is used to spray a spraying liquid obtained by mixing a soluble high-temperature polymer with a solvent on a substrate, and then heat-treated to form a dielectric layer. The ultrasonic spraying process not only makes the spraying liquid spread well on the substrate, and the thickness of the obtained dielectric layer is evenly distributed, but also can prepare an ultra-thin dielectric layer. At the same time, the ultrasonic spraying process only requires simple adjustment of the template according to the corresponding size to obtain a dielectric layer of corresponding size. Compared with the casting, melt extrusion and other processes, the obtained film layer needs to be post-processed after film formation. This application does not require post-processing operations. Then, an internal electrode layer is formed on the above-mentioned dielectric layer, and then the ultrasonic atomization spraying of the spraying liquid is continued on the above-mentioned internal electrode layer and heat-treated to form a dielectric layer. By repeating the above steps, an inner core including at least three dielectric layers and at least two inner electrode layers can be prepared on the substrate, and the dielectric layers and the inner electrode layers in the inner core are alternately stacked, and then hot pressing is performed. The first end electrode is then arranged on one side of the substrate and connected to at least one inner electrode layer, and the second end electrode is arranged on the other side of the substrate and connected to the remaining inner electrode layers. Finally, the device is packaged to obtain the above-mentioned capacitor with good reliability at a high temperature of not less than 150°C.

[0026] In addition, the method for preparing a high-temperature multilayer film capacitor according to the above embodiment of the present invention may also have the following additional technical features:

[0027] In some embodiments of the present invention, the band gap energy of the soluble high-temperature polymer is not less than 3 eV, thereby improving the reliability of the capacitor.

[0028] In some embodiments of the present invention, the spraying liquid is prepared by mixing a soluble high-temperature polymer, an organic semiconductor, and a solvent.

[0029] In some embodiments of the present invention, the trap energy of the charge trap constructed by the soluble high-temperature polymer and the organic semiconductor is not less than 1.5 eV.

[0030] In some embodiments of the present invention, the organic semiconductor comprises At least one of .

[0031] In some embodiments of the present invention, in step (2), the inner electrode layer is a metal foil layer, and the metal foil layer is placed on the dielectric layer for cold pressing, wherein the cold pressing temperature is 30-60°C, the pressure is 10-20t, and the cold pressing is carried out in a vacuum press, and the vacuum negative pressure is not higher than 80Pa; or the inner electrode layer is a metallized electrode, and the metallized electrode is obtained by high vacuum thermal resistance evaporation.

[0032] In some embodiments of the present invention, in step (4), the temperature of the hot pressing is not less than 150°C, the time is not less than 1 hour, the pressure is 1 to 15 tons, and the hot pressing is performed in a vacuum press with a vacuum pressure not higher than 80 Pa. This can make the capacitor core structure more stable and compact.

[0033] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0035] Figure 1 is a structural diagram of a high-temperature multilayer film capacitor according to an embodiment of the present invention;

[0036] Figure 2 1 is a schematic flow chart of a method for preparing a high-temperature laminated film capacitor according to an embodiment of the present invention;

[0037] Figure 3 1 is a schematic diagram of a process flow for preparing a high-temperature laminated film capacitor according to an embodiment of the present invention;

[0038] Figure 4 Figure a is a diagram of Example 1 using fluorinated polyimide A photo of a foil-type multilayer capacitor (f-MLPC) with an active surface area of ​​approximately 5 cm x 5 cm, constructed with thin film as the dielectric layer and aluminum foil as the inner electrode layer. Figure 4 Middle B picture and Figure 4 Figure c in the middle shows f-MLPC soft-encapsulated with cross-linked polydimethylsiloxane and hard-encapsulated with cross-linked epoxy resin; Figure 4 Figure d is a SEM image of the internal cross-sectional structure of the f-MLPC obtained in Example 1; Figure 4 Figure e is an EDS diagram of F in the f-MLPC obtained in Example 1 to represent the distribution of the dielectric layer; Figure 4 Figure f in the middle is an EDS diagram of Al in the f-MLPC obtained in Example 1 to represent the distribution of the aluminum foil in the inner electrode layer;

[0039] Figure 5 1 is a graph showing the frequency variation of capacitance and loss factor of the capacitor of Example 1 at 25° C., 50° C., 100° C., and 150° C.;

[0040] Figure 6 1 is a graph showing the capacitance and loss factor measurements of the capacitor of Example 1 at room temperature under different bending degrees;

[0041] Figure 7Figure a is a schematic diagram of a metallized laminated film capacitor having three dielectric active layers according to Example 2;

[0042] Figure 7 Figure b is a schematic diagram of the internal cross-section of the capacitor obtained in Example 2; Figure 7 Figure c in the middle is fluorinated polyimide A photo of a metallized multilayer film capacitor (m-MLPC) with an active surface area of ​​approximately 2cm x 2cm, constructed with thin film as the dielectric layer and metallized aluminum as the inner electrode layer. Figure 7 d is a cross-sectional view of the m-MLPC prepared in Example 2;

[0043] Figure 8 This is a graph showing the capacitance and dissipation factor measurement results of the capacitor of Example 2 at 150°C. DETAILED DESCRIPTION

[0044] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0045] In one aspect of the present invention, the present invention provides a high temperature laminated film capacitor. Figure 1 The high temperature multilayer film capacitor includes: a substrate 100 , an inner core 200 , a terminal electrode 300 and an encapsulation layer 400 .

[0046] It should be noted that substrate 100 is a conventional material in the art and can be selected by those skilled in the art based on practical needs. For example, substrate 100 includes, but is not limited to, aluminum foil, copper foil, glass plate, or a polymer film with a glass transition temperature of not less than 150°C. Furthermore, substrate 100 has a thickness of not less than 5 μm, for example, 10 to 20 μm.

[0047] According to the capacitor of the above embodiment of the present invention, the inner core 200 includes at least three dielectric layers 201 and at least two inner electrode layers 202. The dielectric layers 201 and the inner electrode layers 202 are alternately stacked, and the dielectric layer 201 located at the bottom of the inner core 200 is provided on the substrate 100. The uppermost end of the inner core 200 is the dielectric layer 201. The dielectric layer 201 located at the uppermost end of the inner core 200 can protect the inner electrode layer 202 adjacent thereto. The dielectric layer 201 includes a soluble high-temperature polymer. Since the soluble high-temperature polymer has a high glass transition temperature and a wide band gap, the capacitor of the present application has great application potential in the field of high-temperature energy storage and can greatly improve the breakdown field strength of the dielectric system. As a result, the capacitor of the present application can maintain good reliability at high temperatures of not less than 150°C. It should be noted that those skilled in the art can select the specific type of soluble high-temperature polymer according to actual needs, for example, a soluble polymer with a glass transition temperature of not less than 150° C. and a band gap of not less than 3 eV.

[0048] According to an embodiment of the present invention, the thickness of the single-layer dielectric layer 201 is 1 to 10 μm. It will be understood by those skilled in the art that the thickness of the dielectric layer 201 can be controlled and adjusted according to the changes in the spraying process and the spraying solution. Those skilled in the art can select the thickness of the dielectric layer 201 according to actual conditions, such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm. Furthermore, the type of the inner electrode layer 202 can be determined according to the type of capacitor. For example, for a foil capacitor, the inner electrode layer 202 uses a metal foil layer, and the metal foil is cold-pressed on the dielectric layer 201, wherein the cold pressing temperature is 30-60°C and the pressure is 10-20t, and the cold pressing is carried out in a vacuum press with a vacuum negative pressure of no more than 80 Pa. For a metallized film capacitor, the inner electrode layer 202 uses a metallized electrode, which is obtained by high vacuum thermal resistance evaporation.

[0049] According to an embodiment of the present invention, the end electrode 300 includes a first end electrode 301 and a second end electrode 302, the first end electrode 301 is arranged on one side of the substrate 100 and is connected to at least one internal electrode layer 202, and the second end electrode 302 is arranged on the other side of the substrate 100 and is connected to the remaining internal electrode layers 202.

[0050] According to some specific embodiments of the present invention, the inner core 200 includes at least three layers of inner electrode layers 202, the first end electrode 301 is connected to the inner electrode layers 202 arranged at intervals, and there is an inner electrode layer 202 between the inner electrode layers 202 arranged at intervals, and the second end electrode 302 is connected to the remaining inner electrode layers 202. It should be noted that the "interval-arranged inner electrode layers 202" can be understood as the interval arrangement between the inner electrode layers 202, for example, including the first inner electrode layer, the second inner electrode layer and the third inner electrode layer in sequence, wherein the positional relationship between the first inner electrode layer and the third inner electrode layer is an interval arrangement. In this way, the parallel connection of the capacitors formed between the inner electrode layers can be achieved, thereby increasing the capacity of the capacitor of the present application.

[0051] According to some specific embodiments of the present invention, one of two adjacent internal electrode layers 202 extends out of the edge of the dielectric layer 201 in a first direction, while the other extends out of the edge of the dielectric layer 201 in an opposite direction. This prevents adhesion between the two adjacent internal electrode layers 202, and both of the two spaced-apart internal electrode layers 202 extend along the same side of the dielectric layer 201, facilitating connection between the terminal electrode 300 and the spaced-apart internal electrode layers 202. Specifically, if the substrate 100 is made of a conductive material such as aluminum foil or copper foil, when the internal electrode layers 202 extending in the same direction are hot-pressed together during the hot-pressing process, it is important to avoid simultaneous contact between the internal electrode layers 202 extending in the same direction and the internal electrode layers 202 extending in opposite directions and the substrate 100. This prevents internal conduction within the device. This can be achieved by widening the size of the dielectric layer 201 located at the bottom end of the inner core 200.

[0052] It should be noted that the end electrodes 300 may be metal filaments, such as copper wires, which are adhered to both ends of the inner core 200 by a high-temperature resistant conductive adhesive such as conductive silver paste.

[0053] According to an embodiment of the present invention, the encapsulation layer 400 encapsulates the substrate 100, the inner core 200, and the end electrode 300, and the ends of the first end electrode 301 and the second end electrode 302 are not encapsulated. According to a specific embodiment of the present invention, the encapsulation layer 400 may include a flexible cross-linked material or a thermosetting material. For example, the flexible cross-linked material uses cross-linked polydimethylsiloxane to achieve soft encapsulation, and the thermosetting material uses cross-linked epoxy resin to achieve hard encapsulation.

[0054] In another aspect of the present invention, the present invention provides a method for preparing the above-mentioned high-temperature multilayer film capacitor. Figure 2 and Figure 3 According to an embodiment of the present invention, the method includes:

[0055] S100: Mix the soluble high-temperature polymer with the solvent to obtain a spray liquid, ultrasonically atomize it, spray it on the substrate, and then heat treat it.

[0056] In this step, a soluble high-temperature polymer is added to a solvent and stirred thoroughly to uniformly disperse the soluble high-temperature polymer in the solvent to obtain a spray liquid, and then the spray liquid is ultrasonically atomized in a spraying device and sprayed on a substrate and then heat-treated to form a dielectric layer on the substrate. At the same time, the ultrasonic spraying process only requires simple adjustment of the template according to the corresponding size to obtain a dielectric layer of the corresponding size. Compared with the casting, melt extrusion and other processes, the obtained film layer needs to be post-processed after film formation. This application does not require post-processing operations. The soluble high-temperature polymer used in this application has a high glass transition temperature and a wide band gap. The high glass transition temperature enhances the application potential of the soluble high-temperature polymer in the field of high-temperature energy storage, and the wide band gap can greatly enhance the breakdown field strength of the dielectric system. For example, the band gap energy of the soluble high-temperature polymer used in this application is not less than 3eV, which can greatly enhance the breakdown field strength of the dielectric system. The ultrasonic spraying method used has a simple process and low equipment cost, and can efficiently prepare high-quality ultra-thin polymer-based dielectric layers over a large area, solving the high cost problem of the existing method of preparing high-quality ultra-thin polymer-based dielectric layers by melt extrusion and biaxial stretching.

[0057] According to an embodiment of the present invention, the glass transition temperature of the above-mentioned soluble high-temperature polymer is not less than 150°C. For example, the soluble high-temperature polymer of the present application includes but is not limited to at least one of fluorinated polyimide, polyimide and polyetherimide, wherein the structure of the fluorinated polyimide is That is, R is one of the following structures: That is, the introduction of -CF3 groups into the polyimide structure can increase the distance between molecular chains, thereby weakening the conjugation, increasing the intrinsic band gap width of polyimide, and thus improving the breakdown field strength of F-PI.

[0058] Preferably, the structural formula of the fluorinated polyimide (F-PI) is And its glass transition temperature is 340℃, and the chain spacing At the same time, its band gap energy is 3.53eV.

[0059] According to an embodiment of the present invention, to further enhance the breakdown field strength of a dielectric system, an organic semiconductor can be added during the preparation of the spray liquid. Specifically, a soluble high-temperature polymer, an organic semiconductor, and a solvent are mixed and then ultrasonically dispersed to prepare the spray liquid. By adding the organic semiconductor to the spray liquid, the soluble high-temperature polymer and the organic semiconductor form a trace complex, forming deep traps that significantly suppress carrier motion, thereby significantly enhancing the breakdown field strength of the dielectric system.

[0060] According to an embodiment of the present invention, the trap energy of the charge trap constructed by the soluble high temperature polymer and the organic semiconductor is not less than 1.5 eV. In order to make the trap energy of the charge trap constructed by the soluble high temperature polymer and the organic semiconductor larger, the organic semiconductor selected in this application has a melting point of not less than 150°C. For example, the organic semiconductor includes but is not limited to (PC61BM), (PC71BM), (DPDI), At least one of (ITIC). Specifically, the structural formula is The trap energy of the charge trap constructed by F-PI and organic semiconductor (PC61BM) is ~2eV.

[0061] It should be noted that the above-mentioned solvent includes a main solvent and an auxiliary solvent. The main solvent is a conventional reagent in this field. As long as the main solvent is volatile and does not react with soluble high-temperature polymers and organic semiconductors, the auxiliary solvent is volatile and helps to reduce the surface tension of the main solvent to improve the spreadability of the solution on the substrate. Those skilled in the art can select the specific type of solvent according to actual conditions. For example, the main solvent includes but is not limited to at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, m-cresol and dimethyl sulfoxide, and the auxiliary solvent includes but is not limited to at least one of acetone and ethanol. Preferably, the solvent includes N,N-dimethylformamide and acetone, and when the volume ratio of N,N-dimethylformamide to acetone is 6:1-8:1, the spray liquid can basically spread completely on the substrate. Specifically, when the solvent is a mixed solution of N,N-dimethylformamide and acetone, in the process of preparing the spray liquid, the soluble high-temperature polymer powder is first added to DMF and dissolved to obtain a transparent solution, then the organic semiconductor is added to the solution and ultrasonically dispersed, and then acetone is added to the dispersion and fully stirred to obtain the spray liquid, and the ultrasonic dispersion power is 160-320W and the frequency is 20kHz.

[0062] According to an embodiment of the present invention, in the above-mentioned spray liquid, the concentration of the soluble high-temperature polymer is 0.01 to 0.05 g / mL, and the volume concentration of the organic semiconductor is 0.1% to 1%. The inventors found that if the concentration of the soluble high-temperature polymer is too low, a large amount of solvent is consumed and the quality of the film deteriorates; if the concentration of the soluble high-temperature polymer is too high, the spray liquid will clog the nozzle; if the volume concentration of the organic semiconductor is too high, the energy storage performance of the film will be seriously deteriorated; if the volume concentration of the organic semiconductor is too low, the performance of the film will be slightly improved. Therefore, the present application uses a spray liquid including a soluble high-temperature polymer with a concentration of 0.01 to 0.05 g / mL and an organic semiconductor with a volume concentration of 0.1% to 1%, which can improve the reliability of the dielectric layer.

[0063] According to an embodiment of the present invention, the ultrasonic atomization and spraying meet at least one of the following requirements: ultrasonic atomization power of 0.8-1.2 W; spraying height of 30-70 mm; spraying feed speed of 10-50 mm / s; spraying liquid flow rate of 0.5-2 ml / min; and air pressure of 0.003-0.01 MPa. To further improve the uniformity of the thin film produced by atomized spraying on the substrate, it is preferred that all of the above requirements are met.

[0064] According to an embodiment of the present invention, the heat treatment can be performed using the following steps: first, the wet film substrate is heated to 40-90°C for 30-60 minutes to obtain a quasi-dry film; then, the quasi-dry film is placed in a 40-90°C forced air oven, heated to 150-250°C by the forced air oven, and maintained for 2-10 hours; then, the film is placed in a vacuum oven at a temperature greater than 150°C for 5-12 hours. Thus, this heat treatment process can completely remove residual solvent from the film.

[0065] S200: forming an inner electrode layer on the dielectric layer

[0066] In this step, an inner electrode layer 202 is formed on the dielectric layer obtained in S100. The type of the inner electrode layer 202 can be determined according to the type of capacitor. For example, for a foil capacitor, the inner electrode layer 202 uses a metal foil layer, and the metal foil is cold-pressed onto the dielectric layer. The specific cold pressing temperature is 30-60°C, the pressure is 10-20 tons, and the cold pressing is performed in a vacuum press with a vacuum negative pressure of no more than 80 Pa. For a metallized film capacitor, the inner electrode layer 202 uses a metallized electrode, which is obtained by high-vacuum thermal resistance evaporation. The size of the metallized electrode can be adjusted by a specific template, thereby improving the matching of the inner electrode layer 202.

[0067] S300: The spraying liquid is ultrasonically atomized and then sprayed on the inner electrode layer and then heat treated.

[0068] In this step, the spraying liquid in S100 is ultrasonically atomized and then sprayed on the inner electrode layer 202, and then heat-treated to form a dielectric layer 201 on the inner electrode layer, wherein the conditions of the spraying liquid composition, ultrasonic atomization, spraying and heat treatment are the same as those in step S100.

[0069] S400: Repeat steps S200 and S300

[0070] In this step, steps S200 and S300 are repeated to alternately stack at least three dielectric layers 201 and at least two inner electrode layers 202 on the substrate 100, and the uppermost end of the inner core 200 is the dielectric layer 201, and then hot pressing is performed. It can be understood by those skilled in the art that the number of dielectric layers 201 and inner electrode layers 202 can be selected according to actual conditions, as long as the dielectric layers 201 and inner electrode layers 202 are alternately stacked and the dielectric layers 201 are located at the lower and upper ends of the inner core 200. Furthermore, the temperature of the hot pressing is not less than 150°C, the time is not less than 1h, the pressure is 1-15t, and the process is carried out in a vacuum machine with a vacuum negative pressure of not more than 80Pa. Under these hot pressing conditions, the capacitor core structure can be made more stable and compact.

[0071] S500: Add terminal electrode

[0072] In this step, a first end electrode 301 is provided on one side of the substrate 100 and connected to at least one internal electrode layer 202, and a second end electrode 302 is provided on the other side of the substrate 100 and connected to the remaining internal electrode layers 202. For example, the inner core 200 includes at least three internal electrode layers 202, the first end electrode 301 is connected to the spaced internal electrode layers 202, and there is an internal electrode layer 202 between the spaced internal electrode layers 202, and the second end electrode 302 is connected to the remaining internal electrode layers 202. In this way, the internal electrode layers can be connected in parallel to form capacitors, thereby increasing the capacity of the capacitor of the present application.

[0073] S600: Packaging the device

[0074] In this step, the device is packaged, for example, the substrate 100, the inner core 200, and the terminal electrode 300 are packaged, and the ends of the first terminal electrode 301 and the second terminal electrode 302 are not packaged, thereby obtaining a high-temperature laminated thin film capacitor. The packaging method is conventional in the art, and those skilled in the art can select it according to actual circumstances. For example, the packaging material can include a flexible cross-linked material or a thermosetting material. For example, the flexible cross-linked material uses cross-linked polydimethylsiloxane to achieve soft packaging, while the thermosetting material uses cross-linked epoxy resin to achieve hard packaging.

[0075] Therefore, this method has simple equipment, low capacitor production cost, and can produce large-area capacitors. This method can produce the aforementioned capacitors with good reliability at high temperatures. It should be noted that the characteristics and advantages of the aforementioned high-temperature multilayer film capacitors also apply to this method and will not be further elaborated here.

[0076] The present invention is described below with reference to specific examples. It should be noted that these examples are merely illustrative and do not limit the present invention in any way.

[0077] The method for preparing the capacitors obtained in Example 1 and Example 2 includes:

[0078] (1) First, F-PI powder (structural formula is ) is added to DMF to dissolve it into a transparent solution, and then acetone is added to the transparent solution to obtain a spray liquid. The spray liquid is ultrasonically atomized and sprayed on a substrate (aluminum foil). After spraying, the substrate is heated to 40-70°C and maintained for 0.5-1h to dry. The substrate is then moved to a 40°C blast oven, heated to 250°C and maintained for 2h. The substrate is then placed in a 200°C vacuum oven for 10h to completely remove the solvent in the film, and finally a dielectric layer is formed on the substrate. The concentration of F-PI in the spray liquid is 0.0139g / ml, and the volume ratio of DMF to acetone is 8:1. The ultrasonic atomization spraying conditions are: ultrasonic atomization power of 1W, spray liquid flow rate of 0.5ml / min, spray width of 1.5mm, spray height of 60mm, spray feed speed of 20mm / s, and air guide pressure of 0.005MPa.

[0079] (2) Aluminum foil is placed on the dielectric layer obtained in step (1) and cold pressed, wherein the cold pressing temperature is 50° C. and the pressure is 15 tons.

[0080] (3) The spraying liquid in step (1) is ultrasonically atomized and then sprayed onto the inner electrode layer obtained in step (2), and then heat-treated to remove the solvent. The heat treatment method is the same as that in step (1).

[0081] (4) Repeat steps (2) and (3) to prepare the required number of dielectric layers and inner electrode layers according to the actual situation, one of the two adjacent inner electrode layers extends out of the edge of the substrate in a first direction, and the other extends out of the edge of the substrate in the opposite direction, and then hot pressing is performed to shape it.

[0082] (5) A first terminal electrode is provided on at least one internal electrode layer on one side of the substrate and is connected to the remaining internal electrode layers. A second terminal electrode is provided on the other side of the substrate and is connected to the remaining internal electrode layers. The internal electrode layers connected to the first terminal electrode are spaced apart from each other, and there is an internal electrode layer between the spaced internal electrode layers. The first terminal electrode and the second terminal electrode are both made of thin copper wire and are adhered to both ends of the device by high-temperature conductive silver paste.

[0083] (6) Encapsulating the device obtained in step (5) by using cross-linked polydimethylsiloxane soft encapsulation or cross-linked epoxy resin hard encapsulation.

[0084] Figure 4 Figure a is a diagram of Example 1 using fluorinated polyimide A photo of a foil-type multilayer capacitor (f-MLPC) with an active surface area of ​​approximately 5 cm x 5 cm, constructed with thin film as the dielectric layer and aluminum foil as the inner electrode layer. Figure 4 Middle B picture and Figure 4 Figure c shows f-MLPC soft-encapsulated with cross-linked polydimethylsiloxane and hard-encapsulated with cross-linked epoxy resin. The internal cross-sectional structure of f-MLPC was examined by scanning electron microscopy (SEM, Figure 4 The EDS diagram of F ( Figure 4 Figure e) is used to represent the distribution of the dielectric layer; the EDS map of Al ( Figure 4 Figure (f) in the middle represents the distribution of the aluminum foil in the inner electrode layer. The EDS image clearly shows the alternating arrangement of F-PI dielectric layers and Al foil electrode layers. The dielectric layer has six active layers and a thickness of ~6 microns, while the electrode layer is ~6 microns thick.

[0085] The capacitance and dissipation factor of the capacitor of Example 1 were measured at 25° C., 50° C., 100° C., and 150° C.

[0086] The capacitance and dissipation factor frequency changes of the capacitor of Example 1 at 25°C, 50°C, 100°C and 150°C are as follows: Figure 5 As shown. Figure 5 It can be seen that within the frequency range of 1kHz-10kHz, the capacitance and dissipation factor do not change much with temperature. The capacitance at all temperatures at 1kHz is ~85nF, and the dissipation factor changes from 0.014 at 25℃ to 0.032 at 150℃.

[0087] The capacitance and dissipation factor of the capacitor of Example 1 were measured at room temperature under different bending degrees.

[0088] The capacitance and loss factor of the capacitor of Example 1 at different bending degrees at room temperature are shown in FIG. Figure 6 .from Figure 6 It can be seen that at room temperature, the capacitance and loss factor of the capacitor under different bending degrees do not change significantly, which indicates that the flexible packaged capacitor exhibits excellent flexible dielectric performance stability.

[0089] Figure 7 Figure a is a schematic diagram of a metallized laminated film capacitor having three dielectric active layers according to Example 2, and its internal cross-sectional diagram is shown in FIG. Figure 7 As shown in Figure b. Figure 7 Figure c in the middle is fluorinated polyimide A physical image of a metallized multilayer film capacitor (m-MLPC) with an active surface area of ​​approximately 2cm×2cm, constructed with a thin film as the dielectric layer and metallized aluminum as the inner electrode layer; the device has a 2mm margin, three dielectric layers, and the external electrodes are thin copper wires adhered to both ends of the device using high-temperature conductive silver paste. Figure 7 d is a cross-sectional view of the m-MLPC prepared in Example 2. It can be seen from the figure that the thickness of the single-layer dielectric layer is 3.4 μm. The capacitance and dissipation factor of the capacitor of Example 2 were measured at 150°C. The measurement results are shown in Figure 8 .from Figure 8 It can be seen that the capacitance at 1kHz at 150°C is 1.87nF and the loss factor is 0.023.

[0090] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0091] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a high-temperature laminated film capacitor, characterized in that: include: (1) mixing a soluble high-temperature polymer, an organic semiconductor, and a solvent, and then ultrasonically dispersing the mixture to prepare a spray liquid, ultrasonically atomizing the spray liquid and spraying it on a substrate, and then heat-treating the mixture to form a dielectric layer on the substrate; (2) forming an internal electrode layer on the dielectric layer; (3) ultrasonically atomizing the spraying liquid and spraying it on the inner electrode layer, followed by heat treatment; (4) repeating steps (2) and (3) to alternately stack at least three dielectric layers and at least two inner electrode layers on the substrate, with the uppermost end of the inner core being the dielectric layer, and then performing hot pressing and shaping; (5) disposing a first terminal electrode on one side of the substrate and connected to the at least one internal electrode layer, and disposing a second terminal electrode on the other side of the substrate and connected to the remaining internal electrode layers; (6) packaging the device obtained in step (5) to obtain a high-temperature laminated film capacitor; The soluble high-temperature polymer is a fluorine-containing polyimide; The glass transition temperature of the soluble high temperature polymer is not less than 150°C; The band gap of the soluble high temperature polymer is not less than 3 eV; The structure of the fluorine-containing polyimide is R is The trap energy of the charge trap constructed by the soluble high-temperature polymer and the organic semiconductor is not less than 1.5 eV; The organic semiconductor is 2. The method according to claim 1, characterized in that In step (2), the inner electrode layer is a metal foil layer, and the metal foil layer is placed on the dielectric layer for cold pressing, wherein the cold pressing temperature is 30-60°C, the pressure is 10-20t, and the cold pressing is performed in a vacuum press with a vacuum negative pressure not higher than 80Pa; or The inner electrode layer is a metallized electrode, and the metallized electrode is obtained by high vacuum thermal resistance evaporation.

3. The method according to claim 1, characterized in that In step (4), the temperature of the hot pressing is not less than 150°C, the time is not less than 1 hour, the pressure is 1 to 15t, and the hot pressing is carried out in a vacuum press with a vacuum negative pressure not higher than 80Pa.

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