Metallized film capacitor based on nano-porous material structure and method of manufacturing the same

Abstract

The application discloses a metalized film capacitor based on a nano-porous material structure and a preparation method thereof. The capacitor comprises a core formed by winding a metalized film, a shell with a containing cavity, a gap-filling layer and an encapsulation layer. The gap-filling layer is formed by an insulating material with a nano-porous structure, continuously fills between adjacent film layers of the core and is in contact with the adjacent film layers; the encapsulation layer is formed by a potting material with a nano-porous structure, continuously fills between the core and the inner wall of the containing cavity, coats the core and is in contact with the outer surface of the core and the inner wall of the containing cavity; and the shell wall of the shell is formed by a material with a nano-porous structure. In the preparation, the gap-filling layer is formed by vacuum impregnation, and the encapsulation layer is formed by injecting a potting material in a negative pressure environment. The gap-filling layer, the encapsulation layer and the shell wall constitute a multi-layer thermal insulation damping system, which can reduce air gap, air convection and vibration resonance, inhibit external heat transfer and core vibration, and improve the heat resistance stability and noise reduction performance of the capacitor.

Description

Technical Field

[0001] This invention relates to the field of capacitor technology, and in particular to a metallized thin-film capacitor based on a nanoporous material structure and its preparation method. Background Technology

[0002] Metallized film capacitors typically consist of a core formed by winding a metallized film and a housing to house the core. Tiny gaps naturally exist between adjacent film layers after winding, and after the core is installed in the housing, an assembly gap also forms between the outer surface of the core and the inner wall of the housing. Existing technologies typically address these gaps using impregnation or potting methods, but ordinary filling materials struggle to form a continuous filling structure within the gaps between film layers that ensures sufficient contact with adjacent layers. Furthermore, air gaps or localized cavities can easily remain between the core and the housing.

[0003] When metallized film capacitors are heated during soldering or operate in high-temperature environments, external heat can easily be transferred to the core through the shell wall and internal gaps, causing the core temperature to rise and thus affecting the dimensional stability and electrical performance of the metallized film. On the other hand, the metallized film will generate micro-vibrations under the action of an alternating electric field. The gaps between the film layers and the cavity between the core and the shell may amplify the vibrations or form acoustic resonance, thereby producing a whistling sound. Summary of the Invention

[0004] The purpose of this invention is to provide a metallized thin-film capacitor based on a nanoporous material structure and its preparation method, which can improve the heat insulation and vibration suppression capabilities of metallized thin-film capacitors.

[0005] To achieve the above objectives, the present invention provides a metallized thin-film capacitor based on a nanoporous material structure, comprising: The core is formed by winding a metallized thin film, with gaps between adjacent film layers. A housing having a receiving cavity, wherein the core is disposed within the receiving cavity; A gap-filling layer, which fills the gaps between adjacent membrane layers of the core, wherein the gap-filling layer is a continuous layer formed of an insulating material with a nanoporous structure and is in contact with the adjacent membrane layers; An encapsulation layer is continuously filled in the gap between the core and the inner wall of the receiving cavity and covers the core, and is in contact with the inner wall of the receiving cavity. The encapsulation layer is a continuous layer formed of a potting material with a nanoporous structure and is in contact with the outer surface of the core and the inner wall of the receiving cavity respectively. The shell wall is a structure formed of a material with a nanoporous structure.

[0006] Preferably, the insulating material forming the gap-filling layer and / or the encapsulation layer is epoxy resin.

[0007] Preferably, the inner wall of the receiving cavity is provided with a positioning bracket, and the core is supported on the positioning bracket and spaced apart from the inner wall of the receiving cavity.

[0008] Preferably, the inner wall of the receiving cavity is formed with a flow channel, which is used to guide the flow of the potting material forming the encapsulation layer when the encapsulation layer is potted.

[0009] Preferably, a buffer space is formed between the core and the bottom wall of the housing, and the encapsulation layer fills the bottom buffer space.

[0010] Preferably, a gap forming portion is provided on the side of the housing near the pin, and a gap is formed between the housing and the PCB board to be mounted based on the gap forming portion.

[0011] The present invention also provides a method for preparing a metallized thin-film capacitor, comprising: A metallized thin film is wound to form a core, such that the core has adjacent film layers and a film layer gap between the adjacent film layers; The core is placed in a vacuum environment to allow the insulating impregnating material to enter the gap between the film layers and to cure the insulating impregnating material to form a continuous gap-filling layer with a nanoporous structure that is in contact with the adjacent film layers within the gap between the film layers. A housing with a receiving cavity is provided, the shell wall of which is formed of a material with a nanoporous structure, and a core having the interstitial layer formed thereon is disposed within the receiving cavity; The shell and the core are preheated, and potting material is injected between the core and the inner wall of the receiving cavity under negative pressure. The potting material continuously fills the gap between the core and the inner wall of the receiving cavity, covers the core, and contacts the outer surface of the core and the inner wall of the receiving cavity respectively. The environment in which the potting compound is located is restored from a negative pressure state to an atmospheric pressure state, and the potting compound is cured to form a continuous encapsulation layer with a nanoporous structure.

[0012] Preferably, the method for forming the gap-filling layer includes: evacuating the space where the core is located to remove air from the gaps between the membrane layers; introducing the insulating impregnating material while maintaining the vacuum state, so that the insulating impregnating material enters the gaps between the membrane layers; and curing the insulating impregnating material after it has impregnated the core.

[0013] Preferably, the inner wall of the receiving cavity is provided with a flow guide groove; when the potting material is injected, the potting material enters the gap between the core and the inner wall of the receiving cavity along the flow guide groove and fills the flow guide groove.

[0014] Preferably, after the core is placed in the receiving cavity, a bottom buffer space is formed between the core and the bottom wall of the housing; when the potting material is injected, the potting material fills the bottom buffer space.

[0015] Compared with existing technologies, the metallized film capacitor provided by the above technical solution can reduce air gaps between film layers and limit film layer vibration because the interstitial layer fills the gaps between the film layers of the core and contacts adjacent film layers; the encapsulation layer continuously fills the space between the core and the shell and contacts the outer surface of the core and the inner wall of the shell respectively, which can reduce air convection and vibration resonance caused by internal cavities; combined with the nanoporous structure of the interstitial layer, encapsulation layer and shell wall, a multi-layer thermal insulation and damping system from the inside to the outside can be formed, reducing the transfer of external heat to the core and suppressing core vibration, thereby improving the thermal stability and noise reduction performance of the metallized film capacitor. Attached Figure Description

[0016] Figure 1 This is a planar cross-sectional view of a capacitor in one embodiment of the present invention, wherein it is in an unencapsulated state.

[0017] Figure 2 for Figure 1 A planar cross-sectional view of the capacitor in its potting state.

[0018] Figure 3 This is a planar cross-sectional view of a capacitor according to another embodiment of the present invention.

[0019] Figure 4 This is a planar cross-sectional view of a capacitor according to another embodiment of the present invention.

[0020] Figure 5 This is a diagram showing the pin arrangement of a capacitor in one embodiment of the present invention.

[0021] Figure 6 A pin arrangement diagram of a capacitor in another embodiment of the present invention.

[0022] Figure 7 This is a flowchart illustrating the manufacturing process of the capacitor in an embodiment of the present invention. Detailed Implementation

[0023] To illustrate the technical content, structural features, objectives, and effects of the present invention in detail, the following description is provided in conjunction with the embodiments and accompanying drawings.

[0024] This embodiment discloses a metallized thin-film capacitor based on a nanoporous material structure, suitable for reflow soldering environments and high-frequency operating scenarios.

[0025] First, it should be noted that, unless otherwise stated, the term "bottom" in this embodiment and the following embodiments refers to the side of the metallized film capacitor facing the PCB board after installation. The term "continuous layer" refers to a layer in which the corresponding material is continuously distributed within the filled area and remains in contact with its boundary surface, without large air channels penetrating the area. Micropores that are naturally formed and isolated from each other during the material curing process do not affect the formation of the continuous layer.

[0026] like Figure 1 and Figure 2 The metallized film capacitor includes a core 10, a housing 2, a gap-filling layer 11, and an encapsulation layer 3.

[0027] The core 10 is disposed in the cavity 20 of the housing 2, the gap filling layer 11 is located in the gap between the membrane layers of the core 10, the encapsulation layer 3 is located between the core 10 and the inner wall of the cavity 20, and the shell wall of the housing 2 has a nanoporous structure, thereby forming a multilayer heat insulation and damping system distributed sequentially from the inside of the core 10 to the outside of the housing 2.

[0028] The core 10 is formed by winding a metallized thin film. The metallized thin film includes a polymer film as a medium and a metal coating disposed on the surface of the polymer film. After winding, each turn of the metallized thin film forms an adjacent film layer, and there are gaps between adjacent film layers caused by the film surface morphology, winding state, and interlayer contact state. The gaps between film layers are tiny spaces between adjacent film layers, not through-holes specifically reserved during the winding process. Keeping adjacent film layers pressed tightly together during winding can reduce the size of the gaps between film layers and their degree of interconnection.

[0029] The interstitial layer 11 fills the gaps between adjacent membrane layers and contacts the adjacent membrane layers defining these gaps. The interstitial layer 11 is formed of an insulating material with a nanoporous structure and is continuously distributed along the winding interlayer of the core 10. The interstitial layer 11 can fill all membrane gaps, or it can fill membrane gaps in the core 10 that have a significant impact on heat transfer and vibration without forming through-hole air channels. After curing, the interstitial layer 11 maintains electrical insulation and transforms the membrane gaps that could originally accommodate air into areas occupied by solid insulating material.

[0030] When the core 10 is placed in an alternating electric field, the metallized thin film undergoes minute periodic deformations. After the interstitial layer 11 comes into contact with adjacent film layers, it constrains the relative motion between the layers and dissipates some vibrational energy through internal material damping. Simultaneously, since there are no longer large air channels between the film layers capable of forming significant acoustic resonance, the possibility of film layer vibrations being amplified by air cavities is reduced. The interstitial layer 11 also forms an inner thermal resistance layer before heat reaches the polymer film, thereby reducing the rate of heat transfer between adjacent film layers.

[0031] The shape and size of the receiving cavity 20 are adapted to the outer contour of the core 10 so that a gap for the encapsulation layer 3 can be maintained between the outer surface of the core 10 and the inner wall of the receiving cavity 20 after the core 10 is installed. The shell wall of the housing 2 is formed of a material with a nanoporous structure. The shell wall does not rely on through-hole ventilation for heat dissipation, but instead uses its internal nanopores to extend the solid heat transfer path and limit the convective heat transfer of the gas within the pores, thereby slowing down the transfer of external heat to the interior of the receiving cavity 20.

[0032] The encapsulation layer 3 continuously fills the gap between the outer surface of the core 10 and the inner wall of the receiving cavity 20, covering the core 10 and contacting both the outer surface of the core 10 and the inner wall of the receiving cavity 20. The encapsulation layer 3 is formed by curing a potting material with a nanoporous structure. The encapsulation layer 3 can cover the sides and bottom of the core 10, and according to the pins 5 (e.g., ...). Figure 5 and Figure 6 The lead-out position covers other non-electrical connection areas of the core 10. After the encapsulation layer 3 is cured, it fixes the core 10 in the receiving cavity 20, and at the same time seals the large-sized cavity between the outer surface of the core 10 and the inner wall of the receiving cavity 20.

[0033] The encapsulation layer 3 adheres to the inner wall of the cavity 20, ensuring that heat transferred through the shell wall must pass through the encapsulation layer 3, which has a nanoporous structure, before reaching the core 10. The interstitial layer 11 further enhances thermal resistance within the core 10. The shell wall, encapsulation layer 3, and interstitial layer 11 work sequentially from the outside in, extending the heat transfer path to the metallized thin film and reducing the temperature rise of the core 10 caused by short-term external thermal shocks. After the encapsulation layer 3 completely covers the core 10, it also restricts the vibration of the core 10 relative to the shell 2 and reduces the degree of noise radiated from the shell 2 after the vibration of the core 10 is transmitted to the shell 2.

[0034] After the encapsulation layer 3 is cured, a small number of tiny pores naturally formed during the potting process are allowed. However, these tiny pores are isolated from each other and do not form air channels that penetrate the receiving cavity 20, nor do they form an independently set vacuum insulation layer. As a result, no large permanent cavities that can generate significant air convection or acoustic resonance are retained in the receiving cavity 20, so that the heat insulation, vibration damping and sealing effects can remain stable during the long-term operation of the capacitor.

[0035] In this embodiment, the term "nanoporous structure" refers to a structure in which nanoscale pores are formed within the material matrix. The nanopores within the material itself differ from the unfilled cavity between the core 10 and the shell 2, and also differ from a vacuum interlayer formed by simply evacuating and sealing the material. The nanoporous structure achieves thermal insulation and damping effects by reducing the effective heat transfer path within the material and increasing the dissipation of vibrational energy within the material.

[0036] On the other hand, in this embodiment, a modified epoxy resin suitable for vacuum impregnation is used to form the gap-filling layer 11, and a modified epoxy resin suitable for potting the housing 2 is used to form the encapsulation layer 3. The two epoxy resins can be formulated differently to meet the wetting requirements of the film gaps and the overall potting requirements of the receiving cavity 20, respectively.

[0037] The modified epoxy resin forming the interstitial layer 11 has fluidity before curing, enabling it to penetrate the interlayer gaps. After curing, it forms a continuous insulating layer with a nanoporous structure. The lower potting viscosity facilitates the penetration of the insulating impregnating material into the wound core 10, reducing the situation where the surface of the core 10 is wetted while air remains inside. The cured interstitial layer 11 is in contact with adjacent film layers, providing electrical insulation, thermal insulation, and damping functions.

[0038] The modified epoxy resin forming the encapsulation layer 3 has a nanoporous structure after curing and exhibits low shrinkage, halogen-free flame retardancy, and resistance to thermal shock. The low shrinkage characteristic reduces the likelihood of the encapsulation layer 3 separating from the outer surface of the core 10 or the inner wall of the cavity 20 during curing, ensuring continuous adhesion. The resistance to thermal shock reduces the possibility of cracking during temperature cycling. No thermally conductive paths formed by continuous overlapping of hard particles such as alumina and mica are present in the encapsulation layer 3 to reduce the rapid transfer of heat to the core 10 through the hard filler.

[0039] It should be noted that both the interstitial layer 11 and the encapsulation layer 3 are formed of nanoporous modified epoxy resin. The difference between the two is that the modified epoxy resin forming the interstitial layer 11 focuses on the fluidity and electrical insulation of entering the interlayer gaps, while the modified epoxy resin forming the encapsulation layer 3 focuses on the low shrinkage, flame retardancy and thermal shock resistance after curing.

[0040] The shell 2 can be made of modified engineering plastics based on polyphenylene sulfide or polybutylene terephthalate, or it can be made of a blended resin that can form a nanoporous shell wall and meet the structural strength requirements. Coupling agents, antioxidants, and glass fibers can be added to the shell 2 material to improve the structural strength and aging resistance of the shell 2. The thermal insulation of the shell 2 is mainly provided by the nanoporous structure of the shell wall itself, and there is no need to set a separate loose powder thermal insulation layer in the receiving cavity 20.

[0041] When the shell 2 adopts a box-shaped integrated structure, the thickness of a single shell wall can be set to 1mm to 3mm. When the shell wall thickness is close to the lower limit of this range, it is beneficial to reduce the product volume and material usage; when the shell wall thickness is close to the upper limit of this range, it is beneficial to improve the mechanical strength of the shell 2 and extend the heat transfer path. The specific thickness can be selected within the above range according to the core 10 size, installation space, and mechanical strength requirements.

[0042] On the other hand, such as Figure 1 and Figure 2In this embodiment, a positioning bracket 21, a flow channel 22 and a bottom buffer space 23 are provided in the receiving cavity 20, and a gap forming part is provided on the side of the housing 2 near the pin 5 to improve the positioning of the core 10, the integrity of the potting and the bottom heat insulation performance.

[0043] The positioning bracket 21 is disposed on the inner wall of the receiving cavity 20 and can adopt a column-mounted structure integrally formed with the housing 2. After the core 10 is inserted into the receiving cavity 20, it is supported by the positioning bracket 21 and limited by the positioning bracket 21, so that the core 10 and the inner wall of the receiving cavity 20 are kept apart. The positioning bracket 21 can be disposed on the side, end or bottom of the core 10 according to the outer contour of the core 10, as long as it can limit the displacement of the core 10 during the potting process and reserve continuous filling space for the encapsulation layer 3.

[0044] The positioning bracket 21 ensures a more uniform gap distribution between the core 10 and the inner wall of the receiving cavity 20, preventing the core 10 from locally pressing against the shell wall and causing the encapsulation layer 3 to become too thin or interrupted at that point. After the potting material enters the receiving cavity 20, it fills the space around the positioning bracket 21 and, after curing, surrounds the positioning bracket 21 within the encapsulation layer 3. Therefore, in addition to providing support and limiting during assembly, the positioning bracket 21, together with the encapsulation layer 3, maintains the stable position of the core 10 within the shell 2.

[0045] A flow channel 22 is formed on the inner wall of the receiving cavity 20 and communicates with the gap between the core 10 and the inner wall of the receiving cavity 20. During filling, the filling material enters the side of the core 10, around the positioning bracket 21, and the bottom of the receiving cavity 20 along the flow channel 22, so that areas far from the filling position can also receive the filling material. The extension direction and number of the flow channels 22 can be set according to the shape of the receiving cavity 20 and the filling position, as long as they can guide the filling material to the area that needs to be filled.

[0046] The flow channel 22 serves only as a flow channel for the potting compound during the potting process. After potting, the potting compound simultaneously fills and solidifies within the flow channel 22, thus preventing the flow channel 22 from forming a permanent airflow channel or heat dissipation trench. The housing 2 does not have convection heat dissipation holes communicating with the receiving cavity 20, preventing external high-temperature airflow from directly entering the receiving cavity 20 through the flow channel 22.

[0047] The housing 2 has a bottom wall, and a bottom buffer space 23 is formed between the core 10 and the bottom wall at the end near the bottom wall. The height of the bottom buffer space 23 can be set to 2mm to 5mm. The encapsulation layer 3 fills the entire bottom buffer space 23 and forms a continuous bottom heat insulation buffer layer after curing. The bottom heat insulation buffer layer is located between the core 10 and the bottom wall of the housing 2, which can increase the thermal resistance required for heat transfer from the PCB board side to the core 10, and buffer the mechanical impact on the core 10.

[0048] like Figures 3 to 6 A gap forming part is provided on the side of the housing 2 near the pin 5, and the pin 5 extends from this side toward the PCB board.

[0049] In one implementation, such as Figure 4 The gap forming part is a protrusion 24 protruding from the bottom outer surface of the housing 2. The protrusion 24 can be spaced-apart bumps. After the capacitor is mounted on the PCB board, the bumps support the housing 2, so that an air gap is formed between the bottom outer surface of the housing 2 and the PCB board.

[0050] In another implementation, such as Figure 3 The gap forming part is a recess 25 that is recessed into the cavity 20 relative to the bottom outer surface of the housing 2. An air gap is formed between the recess 25 and the PCB board that does not directly contact each other.

[0051] The bottom buffer space 23 and the gap forming part form a two-stage bottom heat insulation structure. Heat from the PCB board must first cross the air gap between the housing 2 and the PCB board, and then be transferred to the core 10 through the bottom wall of the housing 2 and the encapsulation layer 3 in the bottom buffer space 23. Since the bottom wall of the housing 2, the encapsulation layer 3 and the air gap are arranged in series, the direct transfer of heat generated by the PCB board to the core 10 can be reduced.

[0052] In another preferred embodiment, such as Figure 7 This invention provides a method for preparing a metallized thin-film capacitor, as detailed below: S1, the metallized thin film is wound to form the core 10. During the winding process, continuous pressure is applied to the wound film layers to keep adjacent film layers in contact, without actively reserving air channels that penetrate the interior of the core 10. The winding length and the shape of the core 10 are determined according to the product's capacity and shape requirements, and a closed buffer covering structure is formed at both ends of the core 10 to reduce the axial flow of air inside the core 10.

[0053] S2, the wound core 10 is sequentially subjected to hot pressing and baking for shaping, end-face metal spraying, electrical charging, and lead connection. Hot pressing and baking maintains the predetermined shape of the wound film; end-face metal spraying forms a metal spray layer at both ends of the core 10; electrical charging is used to eliminate local weak points in the dielectric film; lead connection is used to connect the metal spray layer to the external pins 5. During end-face metal spraying, end-face backing paper can be used to shield the sides of the film to prevent the metal coating from extending to the sides of the film and causing a short circuit between the two electrodes. The end-face backing paper only serves a shielding function during the metal spraying process and is not used as a gap-filling layer 11 or a heat insulation layer.

[0054] S3. Vacuum impregnation is performed on the core 10 after the lead wire connection is completed. The core 10 is placed in the vacuum space of the impregnation equipment, the air in the gaps between the film layers is extracted, and then the insulating impregnating material is introduced while maintaining the vacuum state. Under the combined action of pressure difference and its own fluidity, the insulating impregnating material enters the gaps between adjacent film layers and contacts the surfaces of adjacent film layers. During the impregnation process, the vacuum state can be adjusted step by step to gradually expel the air in the gaps between film layers, reducing the disturbance to the winding structure caused by rapid vacuuming or rapid feeding.

[0055] After the insulating impregnating material fully impregnates the core 10, it is cured to form a continuous interstitial layer 11 with a nanoporous structure. The curing conditions are determined according to the curing characteristics of the insulating impregnating material used. Encapsulating the core 10 after the interstitial layer 11 has cured can prevent deformation of the unformed core 10 during the encapsulation process and can also prevent subsequent potting compound from directly entering the core 10 and affecting the continuity of the interstitial layer 11.

[0056] S4, a housing 2 with a receiving cavity 20 is provided. The shell wall of the housing 2 is formed of a material with a nanoporous structure, and a positioning bracket 21 and a flow channel 22 can be pre-set inside the receiving cavity 20. A core 10 with a gap-filling layer 11 is inserted into the receiving cavity 20, so that the core 10 is supported and confined in the positioning bracket 21. A potting gap is maintained between the core 10 and the inner wall of the receiving cavity 20, and a bottom buffer space 23 is maintained between the end of the core 10 near the bottom wall of the housing 2 and the bottom wall.

[0057] S5. Preheat the housing 2 and core 10 before potting. The preheating temperature can be 40°C to 50°C to reduce the viscosity of the subsequently injected potting compound and improve its flowability. The preheating temperature should allow the potting compound to achieve the required flowability to enter narrow gaps without causing thermal damage to the core 10, the lead 5 connection points, or the housing 2.

[0058] The housing 2 containing the core 10 is fed into a vacuum potting apparatus, and the potting environment is evacuated to a negative pressure of -0.09 MPa to -0.1 MPa to expel air from between the core 10 and the inner wall of the receiving cavity 20, around the positioning bracket 21, inside the guide channel 22, and in the bottom buffer space 23. While maintaining the negative pressure, potting material is injected into the receiving cavity 20. The potting material flows along the guide channel 22 into the gap between the core 10 and the inner wall of the receiving cavity 20, and sequentially fills around the positioning bracket 21 and the bottom buffer space 23.

[0059] S6, after the potting compound fills the area to be potted, the potting environment is gradually restored from a negative pressure state to atmospheric pressure. When atmospheric pressure is restored, the external air pressure acts on the potting compound, causing it to further enter the local narrow space and be compacted, thereby reducing large air bubbles and unfilled cavities. Subsequently, the potting compound is cured to form an encapsulation layer 3 that continuously covers the core 10, contacts the outer surface of the core 10, and adheres to the inner wall of the receiving cavity 20.

[0060] The cured encapsulation layer 3 simultaneously fills the flow channel 22, the area around the positioning bracket 21, and the bottom buffer space 23. A small number of tiny negative pressure pores naturally formed during the curing process can remain inside the encapsulation layer 3, but these tiny pores are isolated from each other and cannot form the large interconnected cavities required for air convection or acoustic resonance. This preparation method does not require a separate vacuum interlayer that is separately evacuated and sealed within the receiving cavity 20.

[0061] By first vacuum impregnating the core 10 and then negative pressure potting the entire encapsulated assembly, the gaps between the film layers and the gaps outside the core 10 can be treated separately. The first filling forms a gap-filling layer 11 inside the core 10, and the second filling forms an encapsulation layer 3 on the outside of the core 10. The two layers work together with the nanoporous shell wall to reduce the air channels inside the core 10 and the receiving cavity 20, and form a continuous thermal insulation and damping system.

[0062] Based on the above structure and preparation method, this embodiment provides an SMT surface mount metallized film capacitor. The dielectric film of the core 10 is made of biaxially oriented polypropylene film or polyethylene terephthalate film, the shell 2 is made of polyphenylene sulfide or polybutylene terephthalate modified engineering plastic with a nanoporous structure, the shell wall thickness is 1 mm to 3 mm, and an encapsulation layer 3 with a thickness of 2 mm to 5 mm is formed in the bottom buffer space 23.

[0063] SMT (Surface Mount Technology) metallized film capacitors use flat copper strips to form short leads 5. These short leads 5 can be L-shaped or gull-shaped, such as... Figure 5 The flat pin 5 forms a surface contact with the PCB board pads to accommodate surface mount and reflow soldering.

[0064] The metallized film capacitor of this embodiment was subjected to a standard reflow soldering test with a peak temperature of 260°C. During the test, the highest temperature inside the core 10 was 112°C. After reflow soldering, no significant drift was observed in the capacitance, dielectric loss, and insulation resistance of the product. Within the test frequency band of 10kHz to 1000kHz, the noise attenuation was 10dB to 100dB, and no significant high-frequency howling was observed. This result indicates that the multilayer structure formed by the interstitial layer 11, the encapsulation layer 3, and the shell wall can reduce the transmission of short-term high temperatures to the core 10 and reduce film vibration and internal cavity resonance.

[0065] In addition, to accommodate through-hole mounting and wave soldering, such as Figure 6 In this embodiment, pin 5 is formed by a long circular metal lead to create a through-hole type metallized thin film capacitor.

[0066] The metallized film capacitor of this embodiment was subjected to a 1000-hour continuous aging test at 150°C. After the test, the capacitance decay was no more than 3%, the increase in dielectric loss was no more than 3%, no breakdown occurred, and there was no obvious noise under AC operating conditions. The constraint of the interstitial layer 11 on the adjacent film layers and the overall encapsulation of the core 10 by the encapsulation layer 3 can reduce the loosening of the film layers and the vibration of the core 10 relative to the housing 2 in long-term high-temperature environments; the encapsulation layer 3 remains in close contact with the inner wall of the receiving cavity 20, which can also reduce the entry of moisture and dust around the core 10.

[0067] Therefore, it can be seen that without changing the internal composite packaging structure, the same housing 2 can be adapted to different assembly methods such as surface mount, through-hole wave soldering, and through-hole reflow soldering by changing the pin 5.

[0068] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A metallized thin-film capacitor based on a nanoporous material structure, characterized in that, include: The core is formed by winding a metallized thin film, with gaps between adjacent film layers. A housing having a receiving cavity, wherein the core is disposed within the receiving cavity; A gap-filling layer, which fills the gaps between adjacent membrane layers of the core, wherein the gap-filling layer is a continuous layer formed of an insulating material with a nanoporous structure and is in contact with the adjacent membrane layers; An encapsulation layer is continuously filled in the gap between the core and the inner wall of the receiving cavity and covers the core, and is in contact with the inner wall of the receiving cavity. The encapsulation layer is a continuous layer formed of a potting material with a nanoporous structure and is in contact with the outer surface of the core and the inner wall of the receiving cavity respectively. The shell wall is a structure formed of a material with a nanoporous structure.

2. The metallized thin-film capacitor according to claim 1, characterized in that, The insulating material forming the gap-filling layer and / or the encapsulation layer is epoxy resin.

3. The metallized thin-film capacitor according to claim 1, characterized in that, The inner wall of the receiving cavity is provided with a positioning bracket, and the core is supported by the positioning bracket and spaced apart from the inner wall of the receiving cavity.

4. The metallized thin-film capacitor according to claim 1, characterized in that, The inner wall of the receiving cavity is formed with a flow guide groove, which is used to guide the flow of the potting material forming the encapsulation layer when the encapsulation layer is potted.

5. The metallized thin-film capacitor according to claim 1, characterized in that, A buffer space is formed between the core and the bottom wall of the housing, and the encapsulation layer fills the bottom buffer space.

6. The metallized thin-film capacitor according to claim 1, characterized in that, A gap forming portion is provided on the side of the housing near the pin, and a gap is formed between the housing and the PCB board to be installed based on the gap forming portion.

7. A method for fabricating a metallized thin-film capacitor, characterized in that, include: A metallized thin film is wound to form a core, such that the core has adjacent film layers and a film layer gap between the adjacent film layers; The core is placed in a vacuum environment to allow the insulating impregnating material to enter the gap between the film layers and to cure the insulating impregnating material to form a continuous gap-filling layer with a nanoporous structure that is in contact with the adjacent film layers within the gap between the film layers. A housing with a receiving cavity is provided, the shell wall of which is formed of a material with a nanoporous structure, and a core having the interstitial layer formed thereon is disposed within the receiving cavity; The shell and the core are preheated, and potting material is injected between the core and the inner wall of the receiving cavity under negative pressure. The potting material continuously fills the gap between the core and the inner wall of the receiving cavity, covers the core, and contacts the outer surface of the core and the inner wall of the receiving cavity respectively. The environment in which the potting compound is located is restored from a negative pressure state to an atmospheric pressure state, and the potting compound is cured to form a continuous encapsulation layer with a nanoporous structure.

8. The method for preparing a metallized thin-film capacitor according to claim 7, characterized in that, The method for forming the gap-filling layer includes: evacuating the space where the core is located to remove air from the gaps between the membrane layers; introducing the insulating impregnating material while maintaining the vacuum state, so that the insulating impregnating material enters the gaps between the membrane layers; and curing the insulating impregnating material after it has impregnated the core.

9. The method for preparing a metallized thin-film capacitor according to claim 7, characterized in that, The inner wall of the receiving cavity is provided with a flow guide groove; when the potting material is injected, the potting material enters the gap between the core and the inner wall of the receiving cavity along the flow guide groove and fills the flow guide groove.

10. The method for preparing a metallized thin-film capacitor according to claim 7, characterized in that, After the core is placed in the receiving cavity, a bottom buffer space is formed between the core and the bottom wall of the housing; When the potting compound is injected, it fills the bottom buffer space.

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