Electrode of thin-film capacitor, preparation method of electrode and thin-film capacitor
By introducing an aluminum powder layer and a dielectric film layer into the electrodes of the film capacitor, the problem of large unit capacity and volume of the existing film capacitor is solved, and an electrode structure with high specific capacitance and stability is achieved.
Patent Information
- Application Number
- CN202411931378.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-26
- Publication Date
- 2025-04-11
AI Technical Summary
The existing film capacitors have large unit capacity and are difficult to meet the high capacity requirements.
The electrode structure of an aluminum foil matrix, an aluminum powder layer and a dielectric film layer is adopted. The aluminum powder layer is formed by sintering aluminum powder or aluminum alloy powder, and the dielectric film layer is formed by softening the resin film.
The specific capacitance of the electrode is added, and the stability of the specific capacitance of the electrode is ensured through the fixing of the dielectric film layer.
Abstract
Description
Technical Field
[0001] The present invention relates to a film capacitor, and in particular to an electrode of a film capacitor with high capacity and a preparation method thereof. Background Art
[0002] Film capacitors have the following characteristics: no polarity, high insulation impedance, excellent frequency characteristics (wide frequency response), and low dielectric loss. Based on the above advantages, film capacitors are widely used in analog circuits. Especially in the signal interconnection part, capacitors with good frequency characteristics and extremely low dielectric loss must be used to ensure that the signal will not be too distorted during transmission.
[0003] The usual method of making film capacitors is to use aluminum or other metal foil as electrodes and overlap and wind them together with plastic film. Since the surface area of aluminum or other metal foil is small, the volume per unit capacity is generally large. Summary of the invention
[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide an electrode for a thin film capacitor with high electrode specific capacity and a preparation method thereof and a thin film capacitor.
[0005] In order to solve the above technical problems, the technical solution proposed in the present invention is: an electrode of a film capacitor, comprising an aluminum foil substrate, an aluminum powder layer and a dielectric film layer; the aluminum powder layer is formed by sintering aluminum powder or aluminum alloy powder on the aluminum foil substrate, the thickness of the aluminum powder layer is 10 μm or less, and the thickness of the aluminum powder layer does not exceed D of the aluminum powder or aluminum alloy powder. 50 The dielectric film layer is arranged on the aluminum powder layer.
[0006] In the above-mentioned electrode, preferably, the dielectric film layer is formed by softening a resin film on an aluminum powder layer.
[0007] In the above-mentioned electrode, preferably, the aluminum powder or aluminum alloy powder has a D 50 The particle size is 1-5μm.
[0008] A method for preparing an electrode of a film capacitor comprises the following steps: 1) Put aluminum powder or aluminum alloy powder slurry into the solvent and disperse it evenly; 2) Add a binder to the solvent and disperse it evenly to form a slurry; 3) coating the slurry in step 2) on an aluminum foil substrate and heating and curing; 4) Sintering aluminum powder or aluminum alloy powder on an aluminum foil substrate; 5) Covering the sintered electrode foil formed in step 4) on the aluminum powder layer with a resin film; 6) Keep the electrode covered with the resin film at 100°C-200°C for 1-5 minutes to soften the PVA film on the surface of the sintered electrode foil.
[0009] In the above-mentioned method for preparing the electrode of the thin film capacitor, preferably, the sintering in step 4) includes the following stages: in the first stage, the temperature is raised to 80-150°C and kept warm for 20 minutes; in the second stage, the temperature is slowly raised to 400-500°C, the heating rate must be within 1°C / min, and the temperature is kept at 400-500°C for 1-2 hours, and a reducing gas is introduced during the insulation stage of the second stage; in the third stage, the temperature is raised to 630-659°C, sintered for 1-5 hours to form a sintered foil, and a reducing gas is introduced in the third stage; the first stage, the second stage and the third stage are all carried out under the protection of an inert gas.
[0010] In the above-mentioned method for preparing the electrode of the thin film capacitor, preferably, the solid content of the slurry in step 2) is 50%-70%.
[0011] In the above-mentioned method for preparing the electrode of the thin film capacitor, preferably, after the slurry is coated on the aluminum foil substrate in the step 3), the thickness of the slurry is 10 μm or less; the thickness of the slurry does not exceed twice the D50 particle size of the aluminum powder or aluminum alloy powder; the D50 particle size of the aluminum powder or aluminum alloy powder is 1-5 μm.
[0012] In the above-mentioned method for preparing the electrode of the thin film capacitor, preferably, the solvent includes one or more of alcohol, ethylene glycol, glycerol, NMP, xylene, and methanol.
[0013] In the above-mentioned method for preparing the electrode of the thin film capacitor, preferably, the binder includes one or more of polyvinyl alcohol resin, polyester resin, epoxy resin, phenolic resin, and PVDF.
[0014] A film capacitor comprises the above-mentioned electrode.
[0015] Compared with the prior art, the advantages of the present invention are: in the present invention, the aluminum powder layer is formed by sintering aluminum powder or aluminum alloy powder on an aluminum foil substrate, and a dielectric film layer is formed on the aluminum powder layer by softening a resin film; the provision of the aluminum powder layer can increase the specific capacitance of the electrode, and at the same time, the resin film is softened on the aluminum powder layer to form a dielectric film layer, which can further fix the aluminum powder or aluminum alloy powder, thereby ensuring the stability of the electrode specific capacitance. DETAILED DESCRIPTION
[0016] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and carefully in combination with preferred embodiments below, but the protection scope of the present invention is not limited to the following specific embodiments.
[0017] It should be noted that when an element is described as being "fixed, fixed, connected or connected to" another element, it can be directly fixed, fixed, connected or connected to the other element, or it can be indirectly fixed, fixed, connected or connected to the other element through other intermediate connectors.
[0018] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Example
[0019] An electrode of a film capacitor, comprising an aluminum foil substrate, an aluminum powder layer and a dielectric film layer; the aluminum powder layer is formed by sintering aluminum powder or aluminum alloy powder on the aluminum foil substrate, and the dielectric film layer is arranged on the aluminum powder layer; the thickness of the aluminum powder layer is 10 μm or less, and generally, the thickness of the aluminum powder layer does not exceed D of the aluminum powder or aluminum alloy powder. 50 Twice the particle size.
[0020] In this embodiment, the dielectric film layer is formed by softening a resin film on the aluminum powder layer; the resin film can be a plastic film such as polyethylene, polypropylene, polystyrene or polycarbonate. In this embodiment, the aluminum powder layer is formed by sintering aluminum powder or aluminum alloy powder on an aluminum foil substrate, and the dielectric film layer is formed by softening the resin film on the aluminum powder layer; the provision of the aluminum powder layer can increase the specific capacitance of the electrode, and the resin film softening on the aluminum powder layer to form a dielectric film layer can further fix the aluminum powder or aluminum alloy powder, thereby ensuring the stability of the specific capacitance of the electrode.
[0021] This embodiment also provides a method for preparing an electrode of a thin film capacitor, comprising the following steps: 1) Put aluminum powder or aluminum alloy powder slurry into a solvent and disperse it evenly; the solvent includes one or more of alcohol, ethylene glycol, glycerol, NMP, xylene, and methanol.
[0022] 2) Add a binder to the solvent and disperse it evenly to form a slurry with a solid content of 50%-70%. The binder includes one or more of polyvinyl alcohol resin, polyester resin, epoxy resin, phenolic resin, and PVDF.
[0023] 3) Apply the slurry from step 2) on the aluminum foil substrate and heat to cure. After applying the slurry on the aluminum foil substrate, the thickness of the slurry is 20 μm or less; the thickness of the slurry is not more than 2 times the D50 particle size of the aluminum powder or aluminum alloy powder; the D50 particle size of the aluminum powder or aluminum alloy powder is 5-10 μm.
[0024] 4) Sintering aluminum powder or aluminum alloy powder on aluminum foil substrate. Sintering includes the following stages: In the first stage, the temperature is raised to 80-150℃ and kept warm for 20 minutes; In the second stage, the temperature is slowly raised to 400-500℃, and the heating rate must be within 1℃ / min, and kept warm at 400-500℃ for 1-2 hours, and reducing gas is introduced during the insulation stage of the second stage; In the third stage, the temperature is raised to 630-659℃, sintered for 1-5 hours to form sintered foil, and reducing gas is introduced in the third stage; The first, second and third stages are all carried out under the protection of inert gas.
[0025] 5) Covering the sintered electrode foil formed in step 4) on the aluminum powder layer with a resin film; 6) The electrode covered with the resin film is kept at 100°C-200°C for 1-5 minutes to soften the PVA film on the surface of the sintered electrode foil. In this embodiment, the softening temperatures of different dielectric films are different, such as polyethylene film starts to soften at 125-135°C, polypropylene film starts to soften at about 150°C, polystyrene film starts to soften at 80°C, and polycarbonate film starts to soften at about 147°C. Different softening temperatures are selected according to the softening film of different dielectric films.
[0026] In this embodiment, a film capacitor is provided, which is made by overlapping and winding two electrodes of this embodiment, and the dielectric film of the electrode is a polystyrene film. The overlapping structure of the electrode and the dielectric film is aluminum foil substrate-aluminum powder layer-dielectric film layer-aluminum foil substrate-aluminum powder layer-dielectric film layer.
[0027] Comparative Example 1 In comparative example 1, the electrode is made of aluminum foil and the dielectric film is made of polystyrene film; the size of the electrode and the dielectric film is the same as that of embodiment 1; during production, two aluminum foils and one dielectric film are overlapped and then rolled together. The overlapping structure of the electrode and the dielectric film is first aluminum foil-dielectric film-second aluminum foil-dielectric film.
[0028] 20 film capacitors of Example 1 and Comparative Example 1 were selected respectively, and the average capacitance values of Example 1 and Comparative Example 1 were 63.7 pF and 46.6 pF respectively.
Claims
1. An electrode for a film capacitor, characterized in that: The invention comprises an aluminum foil substrate, an aluminum powder layer and a dielectric film layer; the aluminum powder layer is formed by sintering aluminum powder or aluminum alloy powder on the aluminum foil substrate, and the dielectric film layer is arranged on the aluminum powder layer; the thickness of the aluminum powder layer is 10 μm or less, and the thickness of the aluminum powder layer does not exceed D of the aluminum powder or aluminum alloy powder. 50 Twice the particle size.
2. The electrode according to claim 1, characterized in that: The dielectric film layer is formed by softening a resin film on the aluminum powder layer.
3. The electrode of the film capacitor according to claim 1, characterized in that: The aluminum powder or aluminum alloy powder has a D 50 The particle size is 1-5μm.
4. A method for preparing an electrode for a thin film capacitor, characterized in that: The following steps are involved: 1) Put aluminum powder or aluminum alloy powder slurry into the solvent and disperse it evenly; 2) Add a binder to the solvent and disperse it evenly to form a slurry; 3) coating the slurry in step 2) on an aluminum foil substrate and heating and curing; 4) Sintering aluminum powder or aluminum alloy powder on an aluminum foil substrate to form an electrode foil; 5) Covering the sintered electrode foil formed in step 4) on the aluminum powder layer with a resin film; 6) Keep the electrode covered with the resin film at 100°C-200°C for 1-5 minutes to soften the PVA film on the surface of the sintered electrode foil.
5. The method for preparing an electrode for a thin film capacitor according to claim 4, characterized in that: The sintering in step 4) includes the following stages: In the first stage, the temperature is raised to 80-150° C. and kept at this temperature for 20 minutes; In the second stage, the temperature is slowly raised to 400-500°C, the heating rate must be within 1°C / min, and the temperature is kept at 400-500°C for 1-2 hours, and reducing gas is introduced during the insulation stage of the second stage; in the third stage, the temperature is raised to 630-659°C, sintered for 1-5 hours to form a sintered foil, and reducing gas is introduced in the third stage; the first, second and third stages are all carried out under the protection of inert gas.
6. The method for preparing an electrode for a thin film capacitor according to claim 4, characterized in that: The solid content of the slurry in step 2) is 50%-70%.
7. The method for preparing an electrode for a thin film capacitor according to claim 4, characterized in that: After the slurry is coated on the aluminum foil substrate in step 3), the thickness of the slurry is 10 μm or less; the thickness of the slurry does not exceed twice the D50 particle size of the aluminum powder or aluminum alloy powder; the D50 particle size of the aluminum powder or aluminum alloy powder is 1-5 μm.
8. The method for preparing an electrode for a thin film capacitor according to claim 4, characterized in that: The solvent includes one or more of alcohol, ethylene glycol, glycerol, NMP, xylene, and methanol.
9. The method for preparing an electrode for a thin film capacitor according to claim 4, characterized in that: The binder includes one or more of polyvinyl alcohol resin, polyester resin, epoxy resin, phenolic resin and PVDF.
10. A film capacitor, characterized in that: The invention comprises the electrode according to any one of claims 1 to 3.