Highly weather-resistant capacitors and potting processes

Abstract

The present invention discloses a highly weather-resistant capacitor and its potting process. The capacitor comprises a core and a shell, the shell being filled with a filler that surrounds the core. The filler comprises epoxy resin layers located at the bottom and opening of the shell, respectively. A polyurethane layer is located between the two epoxy resin layers, and the polyurethane layer is evenly distributed within the polyurethane layer. This method utilizes a comprehensive encapsulation process, including pre-coating an epoxy resin interface layer, polyurethane filling, mixing with the flaky inorganic filler, and oxygen plasma etching, to improve the capacitor's overall permeability and reduce water absorption, thereby enhancing its weather resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of capacitors, and in particular relates to high-weather-resistance capacitors and a potting process. Background Art

[0002] Capacitors are a commonly used electronic or electrical device. Common capacitors are composed of a core, a shell, and a potting compound. Their main purpose is to form environmental isolation for the core through the potting compound and the shell to ensure a long-term stable working environment for the core.

[0003] Common potting materials are mainly resins and oils. The potting of capacitors has a great impact on the weather resistance of capacitors. Researchers in the capacitor field have also been committed to improving the weather resistance of capacitors. Summary of the Invention

[0004] The present invention addresses the problems existing in the above-mentioned prior art and provides a highly weather-resistant capacitor and a potting process.

[0005] A highly weather-resistant capacitor comprises a core and a shell from the inside out. The shell is filled with a filler that wraps the core. The filler comprises epoxy resin layers located at the bottom and opening of the shell, respectively. A polyurethane layer is located between the two epoxy resin layers, and flaky inorganic fillers are evenly distributed in the polyurethane layer.

[0006] Furthermore, a coupling agent is added to the filler.

[0007] Furthermore, the surface of the shell has a rough super-hydrophobic surface.

[0008] Furthermore, an epoxy resin interface layer is formed on the inner surface of the shell.

[0009] The present invention also provides a potting process for a high-weather-resistant capacitor, wherein a core is placed in a shell, and epoxy resin, polyurethane and epoxy resin are sequentially filled into the shell, wherein the polyurethane is mixed with flaky inorganic fillers.

[0010] Furthermore, the surface of the shell is etched using oxygen plasma before filling.

[0011] Furthermore, a layer of epoxy resin is formed on the inner surface of the shell.

[0012] Furthermore, the flaky inorganic filler is made by pressing silicon dioxide or aluminum hydroxide after being hydrophobically modified.

[0013] Furthermore, coupling agents are added to both the epoxy resin and the polyurethane.

[0014] The beneficial effects of the present invention are as follows: the present invention improves the overall anti-permeability of the capacitor and reduces the water absorption rate through a comprehensive packaging method of pre-coating an epoxy resin interface layer, polyurethane filling, mixing of flaky inorganic fillers and oxygen plasma etching, thereby improving the weather resistance of the capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the potting structure of high weather resistance capacitors. DETAILED DESCRIPTION

[0016] Example

[0017] like Figure 1 Figure 2 shows a schematic diagram of the potting structure of a highly weather-resistant capacitor. The potting structure comprises an internal core 300 and an external housing 100. Epoxy resin, polyurethane, and epoxy resin are sequentially poured into the housing 100, forming an epoxy resin layer 201 at the bottom and opening of the housing 100, and a polyurethane layer 202 between the two epoxy resin layers 201.

[0018] No filler is added to the epoxy resin layer 201, and the potting thickness is 1 to 3 mm. The resin curing system composed of the epoxy resin layer 201 and the polyurethane layer 202 has a small free volume and a low polar group concentration after curing, which helps reduce water absorption and extend the service life of the capacitor.

[0019] The above-mentioned polyurethane layer 202 is also mixed with flaky inorganic fillers. The inorganic filler can be silicon dioxide or aluminum hydroxide, and is pressed into sheets under the working conditions of 2 to 5 MPa of the hydraulic press. The plane size of the flaky inorganic filler is 0.1 to 0.5 mm. After adding the inorganic filler, the thermal expansion coefficient of the resin filling body can be reduced, and the stress generated at the interface due to hot and cold cycles can be reduced. At the same time, the thermal conductivity of the resin filling body can be improved, and the heat dissipation effect when the capacitor is in use can be enhanced. After the inorganic filler is pressed into sheets, it is added to the resin filling body to form a "maze effect". The flaky inorganic fillers randomly dispersed in the resin filling body can effectively enhance the barrier properties, thereby tortuously diffusing the path and inhibiting the penetration of moisture, delaying the penetration of water, and enhancing the barrier properties of the potting material.

[0020] The inorganic filler can be hydrophobically modified before being added to the polyurethane layer 202 to enhance its bonding with the resin. This embodiment does not provide a detailed description of the hydrophobic modification of the inorganic filler. Existing modification methods can be used to hydrophobically modify the inorganic filler, such as grafting aluminum hydroxide with methyltrichlorosilane.

[0021] A coupling agent may also be added to the polyurethane layer 202. This creates a strong bond between the resin filler and the inorganic filler, allowing the resin molecules to firmly adhere to the surface of the housing 100 through the coupling agent, thereby enhancing the impermeability of the bonding interface and reducing the water absorption of the capacitor. Common coupling agents include silane coupling agents and titanate coupling agents.

[0022] In this embodiment, before filling the epoxy resin layer 201 and the polyurethane layer 202, a brushing or dipping method can be used to form an epoxy resin interface layer on the inner surface of the shell 100 to assist in bonding. For surfaces that are difficult to bond, the epoxy resin interface layer can enhance the interface bonding strength.

[0023] In addition, before forming an epoxy resin interface layer on the inner surface of the shell 100, an etching operation can be performed on the surface of the shell 100 by an oxygen plasma etching method, which can clean the inner surface of the shell and increase its surface roughness, which is conducive to forming a larger bonding surface. At the same time, the super hydrophobic surface obtained can further improve the shell's anti-permeability.

[0024] Correspondingly, this embodiment also provides a filling process, including the following steps:

[0025] The first step is to etch the surface of the housing 100 using oxygen plasma;

[0026] Step 2: Form an epoxy resin interface layer on the inner surface of the housing 100 by brushing or dipping;

[0027] Step 3: After placing the core 300 in the housing 100 , epoxy resin, polyurethane and epoxy resin are filled in sequence.

[0028] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same.

Claims

1. High weather resistance capacitor, characterized in that, From the inside to the outside, it includes a core (300) and a shell (100), the shell (100) is filled with a filling body that wraps the core (300), and the filling body includes epoxy resin layers (201) respectively located at the bottom and the opening of the shell (100), and a polyurethane layer (202) is located between the two epoxy resin layers (201). The polyurethane layer (202) is also evenly distributed with flaky inorganic fillers, and the flaky inorganic fillers are made of silicon dioxide or aluminum hydroxide that is hydrophobically modified and then pressed.

2. The high weather resistance capacitor according to claim 1, characterized in that: A coupling agent is also added to the filler.

3. The high weather resistance capacitor according to claim 1, characterized in that: The surface of the shell (100) is a rough super-hydrophobic surface.

4. The high weather resistance capacitor according to any one of claims 1 to 3, characterized in that: An epoxy resin interface layer is formed on the inner surface of the shell (100).

5. A potting process for a high weather resistance capacitor according to claim 1, characterized in that: The core (300) is placed in the shell (100), and epoxy resin, polyurethane and epoxy resin are sequentially filled into the shell (100), wherein the polyurethane is mixed with flaky inorganic fillers.

6. The potting process according to claim 5, characterized in that: The surface of the shell (100) is etched using oxygen plasma before filling.

7. A potting process according to claim 5 or 6, characterized in that: A layer of epoxy resin is formed on the inner surface of the housing (100).

8. The potting process according to claim 5, characterized in that: Coupling agents are added to both the epoxy resin and the polyurethane.

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