Thin film capacitor and preparation process thereof

Abstract

The invention relates to a thin film capacitor and a preparation process thereof, the thin film capacitor comprises an insulation assembly, and the insulation assembly comprises a first plastic part, a second plastic part and interelectrode insulation paper; the first plastic part is matched with the side wall of the metal shell, and the direct current terminals of the first busbar and the second busbar are fixed on the first plastic part, so that the first plastic part forms insulation barrier between the direct current terminals and the metal shell; the second plastic part is matched with the side wall of the metal shell, and the alternating current terminals of the first busbar and the second busbar are fixed on the second plastic part, so that the second plastic part forms insulation barrier between the alternating current terminals and the metal shell. Effective insulation barrier is established among the direct-current terminal, the alternating-current terminal and the metal shell, and it is ensured that a safe electrical gap and a creepage distance required by the design are always kept between a live part and the metal shell.

Description

Technical Field

[0001] This invention relates to the field of capacitor technology, and more specifically to a thin-film capacitor and its manufacturing process. Background Technology

[0002] With the rapid development of power electronics technology, metallized film capacitors are being used more and more widely in the new energy field. Film capacitors account for a relatively high proportion of the overall cost, and various new energy industries have an urgent need to reduce the cost of capacitors. At the same time, various industries have increasingly higher requirements for the overcurrent capacity and terminal strength of capacitors. Traditional film capacitors typically consist of a capacitor core assembly (including plates, dielectric, and a metal layer sprayed onto both ends), lead electrodes (usually leads, solder pads, or busbars), a plastic encapsulation shell, and a filling resin (such as epoxy resin or polyurethane). Since the metal layer of the capacitor core assembly is sprayed onto both ends, the typical structure of the lead electrodes also involves them extending from the two ends of the core assembly.

[0003] As motor controllers face increasingly stringent size and weight requirements, more and more capacitors are using the controller's metal casing as the capacitor housing to save space. However, using a metal casing results in the AC and DC terminals being too close to the metal, leading to insufficient creepage distance and clearance, which can easily cause short circuits between the electrodes and the metal casing, resulting in failure. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention aims to provide a thin-film capacitor and its manufacturing process, so as to ensure that the electrode and the metal casing always maintain the safety distance required by the design.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A thin-film capacitor includes a metal casing, a core assembly disposed within the metal casing, a first busbar, a second busbar, and a potting compound, and further includes: An insulating assembly, the insulating assembly comprising a first plastic component, a second plastic component, and inter-electrode insulating paper; The first bus and the second bus are respectively connected to opposite ends of the core assembly, and each has a DC terminal and an AC terminal exposed to the potting compound; The first plastic part mates with the side wall of the metal housing, and the DC terminals of the first bus and the second bus are fixed to the first plastic part so that the first plastic part forms an insulating barrier between the DC terminals and the metal housing. The second plastic component mates with the side wall of the metal housing, and the AC terminals of the first busbar and the second busbar are fixed to the second plastic component so that the second plastic component forms an insulating barrier between the AC terminals and the metal housing; The inter-electrode insulating paper is disposed between the first busbar and the second busbar.

[0006] The DC terminals of the first busbar and the second busbar are fixed to the first plastic part by snap-fit ​​or plug-in method; and / or, the AC terminals of the first busbar and the second busbar are fixed to the second plastic part by snap-fit ​​or plug-in method.

[0007] The DC terminals of the first busbar and the second busbar are engaged and fixed with the positioning protrusions on the first plastic part through slots or positioning holes thereon; The AC terminals of the first busbar and the second busbar are fixed to the second plastic component in one of the following two ways: It engages with the positioning protrusions on the second plastic part through the slots or positioning holes thereon; or it passes directly through the multiple openings on the second plastic part.

[0008] The side wall of the metal casing is provided with a recessed snap-fit ​​section; the first plastic part and the second plastic part are fixed to the side wall of the metal casing by snapping with the snap-fit ​​section.

[0009] The first and second plastic parts are snapped together with the snap-fit ​​segment using one of the following structures: The plastic part has a snap-fit ​​groove, and the two ends of the snap-fit ​​segment have limit steps. When the snap-fit ​​groove is snapped into the snap-fit ​​segment, its two ends abut against the limit steps. The plastic part has a snap-fit ​​groove, and the snap-fit ​​section is provided with a positioning pin. The plastic part is provided with a positioning hole that mates with the positioning pin. The plastic part and the snap-fit ​​section are snap-fitted together and fixed by the cooperation of the ribs and the positioning groove; The method by which the first plastic part is fixed to the snap-fit ​​segment may be the same as or different from the method by which the second plastic part is fixed to the snap-fit ​​segment.

[0010] The insulation assembly further includes an isolator disposed between the core assembly and the bottom of the metal housing.

[0011] The potting compound fills the cavity of the metal casing and encapsulates the core assembly, most of the first and second busbars, and a portion of the first and second plastic parts, leaving only the DC and AC terminals exposed.

[0012] The first bus includes a first electrode plate and a DC terminal and an AC terminal connected to the first electrode plate; the second bus includes a second electrode plate and a DC terminal and an AC terminal connected to the second electrode plate. The thickness of the first electrode sheet is less than the thickness of its DC terminal and AC terminal, and the thickness of the second electrode sheet is less than the thickness of its DC terminal and AC terminal.

[0013] The first electrode sheet, the second electrode sheet, and their DC and AC terminals are welded together, and the surface around the weld is roughened to a roughness Ra ≥ 0.04μm.

[0014] A process for manufacturing a thin-film capacitor includes the following steps: Step 1: Component preparation and preprocessing; Prepare the first busbar and the second busbar, as well as the metal casing, core assembly, first plastic component, second plastic component, separator, and inter-electrode insulating paper; In the fabrication of the first bus and the second bus, the welding portion of the electrode plates of the first bus and the second bus is roughened to make its surface roughness Ra ≥ 0.04μm, and then the DC terminal and the AC terminal are welded to the electrode plates of the first bus and the second bus. Step 2: Welding and integration of core electrical modules; Align the electrode plates of the first busbar with one end face of the core assembly, and align the electrode plates of the second busbar with the other end face of the core assembly; then weld them together sequentially using laser welding technology. After welding is completed, the inter-electrode insulating paper is directly inserted or placed in the predetermined position between the first busbar and the second busbar; Step 3: Construction of the insulation frame; Place the spacer at the bottom of the cavity; The first and second plastic parts are snapped into the side wall of the metal casing; An insulating frame consisting of a first plastic component, a second plastic component, and an insulating component was constructed inside the metal casing. Step 4: Assembly; The core electrical module prepared in the second step is then installed into the insulating frame constructed in the third step. During the installation process, the DC terminals of the first bus and the second bus are snapped or plugged into the fixed first plastic part; the AC terminals of the first and second buses are snapped or plugged into the fixed second plastic part. Step 5: Potting and curing; The prepared liquid potting compound is injected into the cavity of the metal casing. The potting compound covers the core assembly, the electrode plates of the bus, the inter-electrode insulating paper, and part of the first and second plastic parts, leaving only the DC and AC terminals exposed.

[0015] Under the set curing conditions, the potting compound is fully cured to form the finished product; Step 6: Inspection and Packaging; The finished products undergo electrical performance testing and visual inspection. Once they pass the inspection, they are packaged and shipped out of the factory.

[0016] By adopting the above solution, the present invention establishes an effective insulation barrier between the DC terminals, AC terminals, and the metal casing through the systematic arrangement of the first and second plastic parts. This ensures that the live parts and the metal casing always maintain the safety electrical clearance and creepage distance required by the design, fundamentally eliminating the risk of short circuit failure of the casing.

[0017] This invention achieves rapid and precise positioning between terminals and plastic parts through a self-positioning structure that allows for insertion and snap-fit ​​between DC and AC terminals and the first and second plastic parts. This not only significantly improves assembly efficiency but also effectively prevents terminal displacement due to vibration during subsequent potting processes and use, ensuring long-term stability and consistency of the insulation distance.

[0018] Furthermore, the bus of this invention employs a "thick-thin combination" partitioned design, using thicker materials in terminal areas where current is concentrated and heat generation is severe to reduce resistance and enhance mechanical strength, while using thinner materials in the core connection surfaces where current density is lower to save materials and reduce weight. This design achieves effective cost control while ensuring excellent electrical performance and overcurrent capability.

[0019] This invention performs roughening treatment on all laser-welded parts, overcoming the technological challenges of laser welding high-reflectivity materials. This results in sufficient weld penetration and a strong bond, significantly improving the mechanical strength and electrical reliability of the bus internal connections and the electrical connection points between the bus and the core assembly, ensuring stable operation of the product under long-term harsh conditions. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the thin-film capacitor of the present invention; Figure 2 This is an exploded view of the structure of the thin-film capacitor of the present invention; Figure 3 for Figure 1 Cross-section Figure 1 ; Figure 4 for Figure 1 Cross-section Figure 2 ; Figure 5 This is a schematic diagram of the metal casing. Figure 6 for Figure 5 Enlarged view of part A; Figure 7 for Figure 5 Enlarged view of part B; Figure 8 This is a schematic diagram of a thin-film capacitor (metal casing omitted). Figure 9 This is a schematic diagram of a film capacitor (the metal casing and potting compound are omitted). Figure 10 for Figure 9 Exploded structural diagram; Figure 11 This is a schematic diagram of the structure of the first plastic part; Figure 12 An assembly diagram illustrating another embodiment of the first plastic component; Figure 13 for Figure 12 A schematic diagram of local decomposition; Figure 14 This is a structural schematic diagram of the second plastic component; Figure 15 Schematic diagram of the first busbar structure Figure 1 ; Figure 16 Schematic diagram of the first busbar structure Figure 2 ; Figure 17 Schematic diagram of the second busbar structure Figure 1 ; Figure 18 Schematic diagram of the second busbar structure Figure 2 .

[0021] Label Explanation: Metal outer shell 10; cavity 11; side wall 12; first locking section 13; limiting step 131; positioning pin 132; second locking section 14; positioning groove 141; Core assembly 20; First busbar 30; first electrode plate 31; first welding part 311; first DC terminal 32; first AC terminal 33; Second busbar 40; second electrode plate 41; second welding part 411; second DC terminal 42; second AC terminal 43; Potting material 50; First plastic part 60; snap-fit ​​groove 61; positioning protrusion 62; slot 63; positioning hole 64; pin positioning hole 65; Second plastic part 70; positioning rib 71; opening 72; 80 isolation components; 90mm inter-electrode insulating paper. Detailed Implementation

[0022] The specific embodiments of the thin-film capacitor of the present invention will now be described in detail with reference to the accompanying drawings. Those skilled in the art will understand that these descriptions are exemplary and not intended to limit the scope of protection of the present invention.

[0023] This invention discloses a thin-film capacitor, which is particularly suitable for new energy motor controllers with a metal casing 10 as the mounting body.

[0024] See Figures 1 to 4 The film capacitor mainly includes a metal shell 10, a core assembly 20, a first busbar 30, a second busbar 40, a potting compound 50, and an insulating component, which includes a first plastic part 60, a second plastic part 70, an insulating part 80, and inter-electrode insulating paper 90.

[0025] like Figures 5 to 7 As shown, the metal casing 10 is typically made of aluminum or steel, and its interior has a cavity 11 for accommodating components such as the core assembly 20, the first busbar 30, the second busbar 40, and the potting compound 50. The sidewall 12 of the cavity 11 of the metal casing 10 is provided with positioning structures that mate with the first plastic part 60 and the second plastic part 70, such as recessed snap-fit ​​sections. The snap-fit ​​section mates with the first plastic part 60 will be referred to as the first snap-fit ​​section 13, and the snap-fit ​​section mates with the second plastic part 70 will be referred to as the second snap-fit ​​section 14. These positioning structures are used to precisely fix the first plastic part 60 and the second plastic part 70, thereby establishing the assembly reference for the entire internal structure. The film capacitor shown in this embodiment is suitable for use in motor controllers; therefore, in addition to providing the cavity 11 for accommodating components such as the core assembly 20, the first busbar 30, the second busbar 40, and the potting compound 50, the metal casing 10 also has other cavities. In other application scenarios, the metal casing 10 may only provide one cavity 11.

[0026] like Figure 8 and Figure 9 As shown, the core assembly 20 consists of multiple metallized film capacitor cores, arranged in a straight line or matrix within the cavity 11 of the metal casing 10. The first bus 30 and the second bus 40 are connected to the upper and lower end faces of the core assembly 20 (depending on the arrangement of the core assembly 20, they can also be the left and right end faces), respectively, to collect current and lead it outwards. Inter-electrode insulating paper 90 is disposed between the welding areas of the first bus 30 and the second bus 40. Its core function is to achieve internal insulation (inter-electrode insulation) between the positive electrode (first bus 30) and the negative electrode (second bus 40), preventing internal short circuits caused by component contact or excessive distance, and serving as an important barrier for internal electrical safety.

[0027] Encapsulating material 50 (such as epoxy resin) fills the cavity 11 of the metal casing 10, encapsulating most of the core assembly 20, the first bus 30, and the second bus 40, as well as part of the first plastic component 60 and the second plastic component 70, leaving only the DC and AC terminals of the first bus 30 and the second bus 40 exposed. The film capacitor is a passive electronic component in the motor drive system, directly connected between the battery's DC power supply and the inverter's power semiconductor. Its core function is to ensure the stability of the DC bus voltage and improve the overall reliability of the system. The inverter converts DC power into AC power to drive the motor through the power semiconductor, a process that generates pulsations and ripples on the bus voltage. The film capacitor, through its energy storage characteristics, charges and discharges rapidly, effectively suppressing voltage fluctuations and ensuring stable operating voltage for the power devices. In application, the DC terminal of the film capacitor is connected to the battery voltage filtered by a DC filter, and the AC terminal is connected to the power semiconductor. The DC terminals and AC terminals of the first busbar 30 are referred to as the first DC terminal 32 and the first AC terminal 33, and the DC terminals and AC terminals of the second busbar 40 are referred to as the second DC terminal 42 and the second AC terminal 43.

[0028] The first plastic component 60 and the second plastic component 70 are fitted onto the side wall 12 of the metal housing 10 to form a barrier between the first DC terminal 32 and the second DC terminal 42, the first AC terminal 33 and the second AC terminal 43 and the metal housing 10.

[0029] Reference Figure 11 and combined Figure 1 As shown, in this embodiment, the first plastic part 60 is provided with a snap-fit ​​groove 61, which directly snaps onto the first snap-fit ​​segment 13. To ensure the stability of the connection between the first plastic part 60 and the first snap-fit ​​segment 13, limiting steps 131 are provided at both ends of the first snap-fit ​​segment 13. When the first plastic part 60 is snapped onto the first snap-fit ​​segment 13 through the snap-fit ​​groove 61, both ends of the snap-fit ​​groove 61 abut against the limiting steps 131, thereby effectively preventing the movement of the first plastic part 60 and ensuring that the first plastic part 60 can effectively block the first DC terminal 32, the second DC terminal 42, and the metal casing 10. Alternatively, as... Figure 12-13 As shown, to ensure the stability of the connection between the first plastic part 60 and the first snap-fit ​​section 13, a positioning pin 132 can be provided on the first snap-fit ​​section 13, and a pin positioning hole 65 can be provided on the first plastic part 60. When the first plastic part 60 is snapped into the first snap-fit ​​section 13 through the snap-fit ​​groove 61, the positioning pin 132 is inserted into the pin positioning hole 65, thereby effectively preventing the first plastic part 60 from moving.

[0030] The first DC terminal 32 and the second DC terminal 42 are connected to the first plastic part 60 via a snap-fit ​​method (or a plug-in method in practical applications). Specifically, both the first DC terminal 32 and the second DC terminal 42 have slots 63, and the first plastic part 60 has two positioning protrusions 62 that mate with the slots 63. The first DC terminal 32 and the second DC terminal 42 are fixed to the first plastic part 60 by engaging with the positioning protrusions 62 through their slots. The core function of this "protrusion-slot" self-positioning structure is to ensure that the first DC terminal 32 and the second DC terminal 42 are automatically and accurately positioned during assembly, effectively preventing them from shifting during subsequent processes and use, thereby constantly maintaining the required safe electrical clearance and creepage distance between the first DC terminal 32, the second DC terminal 42 and the metal casing 10, achieving reliable electrode insulation. Or, as... Figure 12-13 As shown, both the first DC terminal 32 and the second DC terminal 42 are provided with positioning holes 64, which engage with positioning protrusions 62 (in this case, columnar structures) on the first plastic part 60. When the first DC terminal 32 and the second DC terminal 42 are connected to the first plastic part 60, the positioning protrusions 62 are inserted into the positioning holes 64, thereby achieving self-positioning of the first DC terminal 32 and the second DC terminal 42 with the first plastic part 60.

[0031] Reference Figure 14 and combined Figure 1 As shown, the second snap-fit ​​section 14 is provided with a positioning groove 141, and correspondingly, the side of the second plastic part 70 is provided with a positioning rib 71 that cooperates with the positioning groove 141. The positioning rib 71 is snapped into the positioning groove 141 to fix the second plastic part 70 on the second snap-fit ​​section 14.

[0032] The first AC terminal 33 and the second AC terminal 43 are connected to the second plastic part 70 via a plug-in method (or a snap-fit ​​method). Specifically, the second plastic part 70 has multiple spaced openings 72. The first AC terminal 33 and the second AC terminal 43 are directly inserted into the openings 72 to connect to the second plastic part 70. In this embodiment, the first DC terminal 32, the second DC terminal 42, the first AC terminal 33, and the second AC terminal 43 are all on the same side (i.e., the first snap-fit ​​section 13 and the second snap-fit ​​section 14 are located on the same sidewall 12). When the second plastic part 70 is plugged into the first AC terminal 33 and the second AC terminal 43, no positioning structure is required. However, if the first DC terminal 32, the second DC terminal 42, the first AC terminal 33, and the second AC terminal 43 are not on the same side, a positioning structure is required when the first plastic part 60 and the second plastic part 70 are connected to the first DC terminal 32, the second DC terminal 42, the first AC terminal 33, and the second AC terminal 43 to ensure stability. In addition, the connection method between the second plastic part 70 and the first AC terminal 33 and the second AC terminal 43 can also refer to the connection method between the first DC terminal 32 and the second DC terminal 42 and the first plastic part 60.

[0033] In this embodiment, the connection method between the first plastic part 60 and the first snap-fit ​​segment 13 is different from the connection method between the second plastic part 70 and the second snap-fit ​​segment 14. However, in practical applications, both can choose the same connection method (i.e., both use snap-fit ​​groove 61 to cooperate with snap-fit ​​segment or both use positioning rib 71 to cooperate with positioning groove 141).

[0034] The isolator 80 is disposed between the core assembly 20 and the bottom of the cavity 11 of the metal casing 10. Its function is to achieve electrode shell insulation in the bottom area of ​​the capacitor, and together with the first plastic component 60 and the second plastic component 70, it forms a complete insulation system that completely isolates the charged body from the metal casing 10. The isolator can be made of plastic sheet or insulating paper.

[0035] This embodiment, through the systematic arrangement of the first plastic component 60 and the second plastic component 70, establishes effective insulation barriers between the first DC terminal 32, the second DC terminal 42, the first AC terminal 33, the second AC terminal 43 and the metal casing 10, and between the bottom of the core assembly 20 and the casing. This ensures that the live parts and the metal casing 10 always maintain the safety electrical clearance and creepage distance required by the design, fundamentally eliminating the risk of short circuit failure.

[0036] The self-positioning structure, which connects the first DC terminal 32, the second DC terminal 42, the first AC terminal 33, the second AC terminal 43, and the first plastic component 60 and the second plastic component 70, enables rapid and precise positioning between the terminals and the plastic components. This not only significantly improves assembly efficiency but also effectively prevents the terminals from shifting due to vibration during subsequent potting processes and use, ensuring the long-term stability and consistency of the insulation distance.

[0037] like Figures 15 to 18 As shown, in this embodiment, the first bus 30 includes a thinner first electrode sheet 31 and thicker first DC terminal 32 and first AC terminal 33. Similarly, the second bus 40 also includes a thinner second electrode sheet 41 and thicker second DC terminal 42 and second AC terminal 43. In this embodiment, the first DC terminal 32 and first AC terminal 33 are separate designs, while the second DC terminal 42 and second AC terminal 43 are integrated designs. In actual use, the integrated design or separate design can be determined according to the usage environment. This "thick and thin combination" partitioned design aims to use thicker materials for external connection terminals where current is concentrated and heat generation is severe, thereby reducing resistance and enhancing mechanical strength; and to use thinner materials for core connection surfaces with lower current density, thus achieving material savings, cost reduction, and weight reduction while ensuring electrical performance.

[0038] The components of the first busbar 30 and the second busbar 40, as well as their end faces with the core assembly 20, are all laser-welded. To ensure the welding quality of the high-reflectivity metal material, a roughening treatment (Ra ≥ 0.04 μm) is performed around all laser welds. This treatment significantly improves the material's absorption rate of laser energy, thereby obtaining high-quality welds with sufficient penetration and high strength, fundamentally improving the reliability and consistency of electrical connection points.

[0039] Based on the above thin-film capacitor structure, this invention also discloses a fabrication process for a thin-film capacitor, specifically including the following steps: Step 1: Component preparation and preprocessing; Prepare a first busbar 30 and a second busbar 40, and prepare a metal casing 10, a core assembly 20, a first plastic component 60, a second plastic component 70, a separator 80, and inter-electrode insulating paper 90.

[0040] Pre-treatment is performed on the first busbar 30 and the second busbar 40: All areas planned for welding (including the connection between the first electrode plate 31 and the first DC terminal 32 and the first AC terminal 33, the connection between the second electrode plate 41 and the second DC terminal 42 and the second AC terminal 43, and the connection between the first electrode plate 31, the second electrode plate 41 and the core assembly 20) are roughened to ensure a surface roughness Ra ≥ 0.04 μm. Figure 16 and Figure 18 As shown, after roughening treatment, a first weld portion 311 will be formed on the first electrode sheet 31, and a second weld portion 411 will be formed on the second electrode sheet 41. Roughening treatment can be achieved through processes such as sandblasting, chemical etching, or laser texturing, with the aim of significantly improving the energy absorption rate during subsequent laser welding.

[0041] Step 2: Welding and integration of core electrical modules; Align the electrode plates of the first busbar 30 with one end face of the core assembly 20, and align the electrode plates of the second busbar 40 with the other end face of the core assembly 20. Then, using a welding process, reliably weld them together sequentially. Because the welding area has undergone roughening pretreatment, a high-quality weld with sufficient penetration and high strength is formed, ensuring the ultimate reliability of the electrical connection.

[0042] After welding, the inter-electrode insulating paper 90 is directly inserted or placed in the predetermined position between the first busbar 30 and the second busbar 40. Its core function is to directly establish a reliable insulating barrier inside the product to prevent short circuits between the positive and negative electrodes (i.e., to achieve inter-electrode insulation).

[0043] At this stage, a fully functional core electrical module integrating the core assembly 20, busbar, and inter-electrode insulation paper 90 is assembled.

[0044] In this invention, the welding process can specifically employ methods such as tin soldering, resistance welding, and laser welding.

[0045] Step 3: Construction of the insulation frame; Place the spacer 80 at the bottom of the cavity 11.

[0046] The first plastic part 60 and the second plastic part 70 are fastened to the corresponding snap-fit ​​section on the side wall 12 of the metal shell 10 through the snap-fit ​​structure (such as snap-fit ​​groove 61 or positioning groove 141) on their sides, so that they are precisely and firmly fixed in the predetermined position.

[0047] Thus, a stable insulating frame consisting of the first plastic component 60, the second plastic component 70, and the insulating component 80 is constructed within the metal casing 10, preparing it for connection to the core electrical module.

[0048] Step 4: Assembly; The core electrical module prepared in the second step is then installed into the insulating frame constructed in the third step. During the installation process, the mechanical connection and positioning of the bus terminals and corresponding plastic parts are completed simultaneously: the first DC terminals 32 and 42 of the first bus 30 and the second bus 40 are snapped or plugged into the fixed first plastic part 60; the first AC terminals 33 and 43 of the first bus 30 and the second bus 40 are snapped or plugged into the fixed second plastic part 70.

[0049] This step allows the core electrical module to be precisely positioned and suspended in the insulating frame via its terminals, achieving complete electrical isolation from the metal housing 10.

[0050] Step 5: Potting and curing; The prepared liquid potting compound 50 (such as epoxy resin mixture) is injected into the cavity 11 of the metal shell 10 under vacuum, so that it completely fills all the remaining space.

[0051] The potting compound 50 encapsulates the core assembly 20, the bus electrode plates, the inter-electrode insulating paper 90, and part of the first plastic part 60 and the second plastic part 70, leaving only the first DC terminal 32, the second DC terminal 42, the first AC terminal 33, and the second AC terminal 43 exposed.

[0052] Under the set curing conditions, the potting compound 50 is fully cured to form a solid insulating and thermally conductive body that binds all internal components together, achieving final mechanical fixation, environmental sealing, and insulation enhancement.

[0053] Step 6: Inspection and Packaging. Conduct electrical performance tests (capacity, loss, withstand voltage) and visual inspections on the finished products. Once qualified, package and ship the product.

[0054] This invention ensures the precision and stability of the insulation distance between the live part and the metal casing 10 through a pre-constructed insulating frame and self-positioning connection between the terminals and the plastic parts, fundamentally guaranteeing the insulation safety of the product's electrode casing. From the inside out, from electrical connection to mechanical insulation, and then to overall packaging, each step provides a systematic and progressive guarantee for the product's final performance and long-term reliability.

[0055] The above description is merely an embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A thin-film capacitor, comprising a metal casing, a core assembly disposed within the metal casing, a first busbar, a second busbar, and a potting compound, characterized in that, Also includes: An insulating assembly, the insulating assembly comprising a first plastic component, a second plastic component, and inter-electrode insulating paper; The first bus and the second bus are respectively connected to opposite ends of the core assembly, and each has a DC terminal and an AC terminal exposed to the potting compound; The first plastic part mates with the side wall of the metal housing, and the DC terminals of the first bus and the second bus are fixed to the first plastic part so that the first plastic part forms an insulating barrier between the DC terminals and the metal housing. The second plastic component mates with the side wall of the metal housing, and the AC terminals of the first busbar and the second busbar are fixed to the second plastic component so that the second plastic component forms an insulating barrier between the AC terminals and the metal housing; The inter-electrode insulating paper is disposed between the first busbar and the second busbar; The DC terminals of the first busbar and the second busbar are engaged and fixed with the positioning protrusions on the first plastic part through slots or positioning holes thereon; The AC terminals of the first busbar and the second busbar are fixed to the second plastic component in one of the following two ways: It engages with the positioning protrusions on the second plastic part through the slots or positioning holes thereon; or it passes directly through the multiple openings on the second plastic part.

2. A thin-film capacitor according to claim 1, characterized in that, The side wall of the metal casing is provided with a recessed snap-fit ​​section; the first plastic part and the second plastic part are fixed to the side wall of the metal casing by snapping with the snap-fit ​​section.

3. A thin-film capacitor according to claim 2, characterized in that, The first and second plastic parts are snapped together with the snap-fit ​​segment using one of the following structures: The plastic part has a snap-fit ​​groove, and the two ends of the snap-fit ​​segment have limit steps. When the snap-fit ​​groove is snapped into the snap-fit ​​segment, its two ends abut against the limit steps. The plastic part has a snap-fit ​​groove, and the snap-fit ​​section is provided with a positioning pin. The plastic part is provided with a positioning hole that mates with the positioning pin. The plastic part and the snap-fit ​​section are snap-fitted together and fixed by the cooperation of the ribs and the positioning groove; The method by which the first plastic part is fixed to the snap-fit ​​segment may be the same as or different from the method by which the second plastic part is fixed to the snap-fit ​​segment.

4. A thin-film capacitor according to claim 1, characterized in that, The insulation assembly further includes an isolator disposed between the core assembly and the bottom of the metal housing.

5. A thin-film capacitor according to claim 1, characterized in that, The potting compound fills the cavity of the metal casing and encapsulates the core assembly, most of the first and second busbars, and a portion of the first and second plastic parts, leaving only the DC and AC terminals exposed.

6. A thin-film capacitor according to claim 1, characterized in that, The first bus includes a first electrode plate and a DC terminal and an AC terminal connected to the first electrode plate; the second bus includes a second electrode plate and a DC terminal and an AC terminal connected to the second electrode plate. The thickness of the first electrode sheet is less than the thickness of its DC terminal and AC terminal, and the thickness of the second electrode sheet is less than the thickness of its DC terminal and AC terminal.

7. A thin-film capacitor according to claim 6, characterized in that, The first electrode sheet, the second electrode sheet, and their DC and AC terminals are welded together, and the surface around the weld is roughened to a roughness Ra≥ 0.04μm.

8. A manufacturing process for a thin-film capacitor, characterized in that, Includes the following steps: Step 1: Component preparation and preprocessing; Prepare the first busbar and the second busbar, as well as the metal casing, core assembly, first plastic component, second plastic component, separator, and inter-electrode insulating paper; In the fabrication of the first bus and the second bus, the welding portion of the electrode plates of the first bus and the second bus is roughened to make its surface roughness Ra ≥ 0.04μm, and then the DC terminal and the AC terminal are welded to the electrode plates of the first bus and the second bus. Step 2: Welding and integration of core electrical modules; Align the electrode plates of the first busbar with one end face of the core assembly, and align the electrode plates of the second busbar with the other end face of the core assembly; then weld them together sequentially using a welding process. After welding is completed, the inter-electrode insulating paper is directly inserted or placed in the predetermined position between the first busbar and the second busbar; Step 3: Construction of the insulation frame; Place the spacer at the bottom of the cavity; The first and second plastic parts are snapped into the side wall of the metal casing; An insulating frame consisting of a first plastic component, a second plastic component, and an insulating component was constructed inside the metal casing. Step 4: Assembly; The core electrical module prepared in the second step is then installed into the insulating frame constructed in the third step. During the installation process, the DC terminals of the first bus and the second bus are snapped or plugged into the fixed first plastic part; the AC terminals of the first and second buses are snapped or plugged into the fixed second plastic part. Step 5: Potting and curing; The prepared liquid potting compound is injected into the cavity of the metal shell. The potting compound wraps the core assembly, the electrode plates of the bus, the inter-electrode insulating paper, and part of the first and second plastic parts, leaving only the DC and AC terminals exposed. Under the set curing conditions, the potting compound is fully cured to form the finished product; Step 6: Inspection and Packaging; The finished products undergo electrical performance testing and visual inspection. Once they pass the inspection, they are packaged and shipped out of the factory.

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