Customized film capacitor without injection molding plastic shell
By employing vacuum forming technology and limiting rib design, the problems of long production cycles and high costs associated with injection-molded plastic-shell film capacitors have been solved, enabling low-cost and rapid production of customized film capacitors adaptable to various complex shapes.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- NISTRONICS JIANGXI
- Filing Date
- 2025-05-09
- Publication Date
- 2026-04-28
AI Technical Summary
Existing manufacturing technologies for injection-free plastic-cased film capacitors suffer from long processing cycles, high costs, and high maintenance expenses. In particular, when customers require unique appearance designs, the complexity of the molds increases significantly, leading to further cost increases.
A blister box with the same shape as the custom film capacitor is made using a blister forming process, and limiting ribs are set on its inner side wall. The core of the film capacitor is placed into the blister box and cured with potting material to form a thin-walled, lightweight, and low-cost custom film capacitor without injection molding.
It significantly shortens the production cycle, reduces production costs, and adapts to various complex shapes, providing efficient and low-cost customized protection.
Smart Images
Figure CN224177223U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of film capacitor technology, and in particular to a custom film capacitor with a non-injection-molded plastic shell for use in new energy vehicles. Background Technology
[0002] With the rapid development of power electronics technology, metallized film capacitors have been widely used in new energy, automotive electronics, rail transportation, industrial control, frequency conversion and other fields due to their advantages such as high safety, long life, high temperature and current resistance, and stable performance. In particular, the demand for film capacitors in the field of new energy vehicles is increasing. However, the internal space of new energy vehicles is getting smaller and smaller, and the space left is gradually no longer square, but may be various shapes such as circles, triangles, ellipses, and even rings, square rings, polygons, etc. At the same time, the shell will also be varied in shape to adapt to the space assembly.
[0003] Metallized film capacitors mainly consist of multiple cores, busbars, plastic shells, and epoxy potting compound. The main process involves welding the cores in parallel to the busbars, directly inserting them into the plastic shell, applying epoxy potting compound, and then curing at high temperature for encapsulation. External mounting terminals on the busbars are left exposed for performance testing and customer installation. Existing plastic shells are generally square with mounting holes, produced by injection molding of plastic particles. Due to the large size of the products, the injection molds are typically large, resulting in high costs, often exceeding 200,000 yuan. They also have a limited lifespan; after a certain number of injection cycles, the mold needs to be remade. Mold maintenance is also an issue during use, adding to the cost. Consequently, injection-molded shells account for 25% to 30% of the cost of customized film capacitors for new energy vehicles.
[0004] Custom capacitors are used in new energy vehicles, and currently they are mainly fixed with screws. Car manufacturers hope to obtain a capacitor whose shape can match the space of the installation location and be sealed with potting material. This would not only free up space in the car, but also reduce the need for screw fixing.
[0005] The future development trend of this type of metallized film capacitor is to invent a low-cost, injection-free, custom-designed film capacitor for new energy vehicles to reduce costs.
[0006] Currently, existing injection-free plastic shell technology mainly uses metal sheets to make corresponding molds, puts the capacitor core into them, then uses potting compound to encapsulate and cure it, and finally removes the mold. The main problems with this technology are high cost, mass production generally requires a large number of molds, and the mold processing cycle is long and costly, and the subsequent maintenance costs are high, which is not conducive to mass production. If the appearance shape required by the customer is more unique, the complexity of the mold will increase significantly, and the cost will also increase accordingly. Utility Model Content
[0007] To address the problems of existing injection-free plastic-shell film capacitor manufacturing technologies, which primarily rely on metal sheet molds, resulting in long processing cycles, high costs, and high maintenance expenses, as well as the increasing complexity and cost of molds due to diverse and sometimes unusual customer-required designs, this invention provides an injection-free plastic-shell custom film capacitor. By employing existing vacuum forming technology, a vacuum-formed box with the same shape as the custom film capacitor, thin walls, light weight, low material consumption, and low cost can be quickly produced. Multiple evenly distributed ribs are created on the inner wall of the vacuum-formed box. The film capacitor core is placed inside the box and then encapsulated and cured with potting material, resulting in a uniformly thick-walled injection-free plastic-shell custom film capacitor. This significantly shortens the production cycle and saves production costs.
[0008] To achieve the above objectives, this utility model provides a custom film capacitor without injection molding and encapsulation, including two types: one is a custom film capacitor with encapsulation material without an injection mold, and the other is a custom film capacitor with a blister-formed shell. The custom film capacitor with encapsulation material without an injection mold includes a custom film capacitor core and an encapsulation layer. The custom film capacitor with blister-formed shell includes a custom film capacitor core, an encapsulation layer, and a blister box. The blister box is prepared using existing blister forming technology, and the encapsulation layer is formed by encapsulating the core using the blister box, wrapping around the outer wall of the core. The shape of both the encapsulation layer and the blister box is consistent with the shape of the core, and the wall thickness is uniform.
[0009] Preferably, the potting compound layer is made of thermosetting epoxy resin with a thickness of 2-5 mm;
[0010] Preferably, the blister shell is made of one of the transparent engineering plastics, PET, PP, or PVC, with a thickness of 1 to 2 mm.
[0011] Preferably, the customized film capacitor can be any shape required by the customer, such as circular, triangular, elliptical, annular, square, or polygonal.
[0012] This utility model also provides a method for manufacturing the above-mentioned custom thin-film capacitor without injection molding, including the following steps:
[0013] S1. Making the blister box: A blister mold is made according to the shape and size of the film capacitor required by the customer. The blister mold can be made of wood film, resin film, ceramic film, or plaster mold. Multiple evenly distributed elongated grooves are set on the outer periphery of the blister mold, and these elongated grooves are perpendicular to the bottom surface. Multiple evenly distributed elongated grooves or annular grooves are set on the bottom surface of the blister mold. The elongated grooves are located in the middle of the corresponding sidewalls, with a 4-5mm gap between each end and the edge of the sidewall. The raw material for the blister box is engineering plastic, specifically a transparent plastic of PET, PP, or PVC. The blister mold is placed in a blister forming machine, which vacuum-forms the blister. After cooling and demolding, the blister box is obtained. The thickness of the blister box is set to 1-2mm.
[0014] Multiple elongated limiting ribs are formed on the inner sidewall of the outer periphery of the blister box, and multiple elongated or annular limiting ribs are formed on the inner bottom wall of the blister box. The thickness of the elongated or annular limiting ribs is consistent with the thickness of the potting material of the film capacitor.
[0015] S2. Potting: Place the film capacitor core package into the blister pack, ensuring that the limiting ribs inside the blister pack are all abutting against the corresponding side walls of the core package. Inject potting material into the space between the blister pack and the core package. Use thermosetting epoxy resin potting material, which is liquid at room temperature. After injection, it will fill all gaps between the core package and the blister pack, with the upper end covering the upper surface of the core package (leaving out the capacitor leads). The thickness of the covering is set to 2-5 μm.
[0016] The setting of the limiting ribs ensures that the wall thickness of the potting compound wrapped around the outside of the core package is uniform.
[0017] S3. Heat curing: Place the potted product from step S2 into a curing machine for heat curing. The heat curing temperature is 80-90℃ and the heat curing time is 2.5-3.5h. The potting material will wrap and seal the core package and fix the core package to the blister box into an integrated structure, thus obtaining the finished blister shell customized film capacitor.
[0018] Preferably, in step S2, before placing the film capacitor core package into the blister box, a silicone oil-based insulating agent is coated on the inner wall and the limiting ribs of the blister box.
[0019] After heating and curing in step S3, the potting compound will not stick to the blister pack. After cooling, the core package encapsulated by the potting compound is removed from the blister pack. At this time, grooves are left on the outer peripheral sidewall and bottom wall of the potting compound layer at the positions corresponding to the limiting ribs. The potting compound is used to fill each groove and then heated and cured to obtain a finished product of a custom film capacitor encapsulated by potting compound without a plastic shell.
[0020] Preferably, in step S1, the cross-section of the elongated limiting rib and the annular limiting rib is semi-circular or trapezoidal, with a width of 2-10 mm and a height consistent with the thickness of the potting compound, set to 2-5 mm. The elongated limiting rib is located in the middle of the inner side surface, does not penetrate the entire surface, and its two ends are 4-5 mm away from the corresponding edge of the inner side surface.
[0021] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. This utility model innovates by customizing the encapsulation method of the capacitor, eliminating the existing injection-molded plastic shell. According to the customer's required appearance shape, a blister box with the same shape as the film capacitor is made and epoxy resin potting encapsulation process is carried out. The sample production cycle is short. While ensuring product performance, the cost is greatly reduced. It has the advantages of easy operation, high efficiency and high reliability.
[0022] 2. This utility model ensures uniform encapsulation thickness of capacitor potting material by setting multiple evenly distributed limiting ribs on the inner side wall of the blister box.
[0023] 3. This utility model eliminates the existing injection molding steel mold and injection molding plastic shell, and replaces it with a lower cost and higher efficiency blister shell mold and blister shell, reducing costs by 20-30%; the blister shell design is highly flexible, adaptable to various complex shapes, can accurately fit the product contour, and provide customized protection. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the process flow state structure of Embodiment 1 of this utility model;
[0025] Figure 2 This is a schematic diagram of the blister box structure of Embodiment 1 of this utility model;
[0026] Figure 3 This is a schematic diagram of the process flow state structure of Embodiment 2 of this utility model;
[0027] Figure 4 This is a schematic diagram of the process flow state structure of Embodiment 3 of this utility model;
[0028] Figure 5 This is a schematic diagram of the blister box structure in Embodiment 3 of this utility model;
[0029] Figure 6 This is a schematic diagram of the process flow state structure of Embodiment 4 of this utility model.
[0030] In the diagram: 1. Film capacitor core package, 2. Blister box, 201. Long strip limiting rib, 202. Circular limiting rib, 3. Encapsulating material, 301. Groove. Detailed Implementation
[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0032] like Figure 1 As shown, Example 1 is a method for preparing a custom-made square blister-shell film capacitor, which includes the following steps:
[0033] S1. Making the blister box: A square blister mold is made according to the required dimensions of the film capacitor. The blister mold is made of wood film, and two evenly distributed elongated grooves are set on the outer sides and bottom of the blister mold. The elongated grooves on the outer sides are perpendicular to the bottom surface, and the elongated grooves are located in the middle of the corresponding side. The two ends are left with a 4mm gap from the corresponding edge of the outer side. The raw material of the blister box is PET transparent engineering plastic. The blister mold is placed in the blister forming machine, and the blister forming machine vacuum forms the blister. After cooling and demolding, the blister box 2 is obtained.
[0034] like Figure 2 As shown, the blister box 2 is a square box with an opening at the top and a thickness of 2mm. Two evenly distributed elongated limiting ribs 201 are formed on the inner side walls and bottom wall of the blister box 2. The cross-section of the elongated limiting rib 201 is semi-circular, the width is 4mm, and the height is the same as the thickness of the potting material 3, which is 2mm. The elongated limiting rib 201 is located in the middle of each inner side and does not penetrate the entire surface. The two ends are 4mm away from the corresponding edge of the inner side.
[0035] S2. Encapsulation: Place the film capacitor core package 1 into the blister box 2, so that the long strip limiting ribs 201 inside the blister box 2 are all abutting against the corresponding side walls of the core package 1. Inject the encapsulating material 3 into the space between the blister box 2 and the core package 1. The thermosetting epoxy resin encapsulating material is used. The encapsulating material 3 is liquid at room temperature. After injection, it will fill all the gaps between the core package 1 and the blister box 2, and the upper end will cover the upper surface of the core package 1 (leaving the capacitor leads 2-5mm).
[0036] The setting of the long strip limiting rib 201 ensures that the wall thickness of the potting material 3 wrapped around the outside of the core package 1 is uniform.
[0037] S3. Heating and curing: The potted product from step S2 is placed in a curing machine for heating and curing. The heating and curing temperature is 80-90℃ and the heating and curing time is 2.5-3.5h. The potting material 3 will wrap and seal the core package 1 and fix the core package 1 and the blister box 2 into an integral structure to obtain the finished square blister plastic shell customized film capacitor.
[0038] like Figure 3 As shown, Example 2 is a method for preparing a custom thin-film capacitor encapsulated with a square, shell-less potting compound, including the following steps:
[0039] S1. Making the blister box: A square blister mold is made according to the required dimensions of the film capacitor. The blister mold is made of wood film, and two evenly distributed elongated grooves are set on the four sides and the bottom surface of the blister mold. The elongated grooves on the four sides are perpendicular to the bottom surface and are located in the middle of the corresponding side. The two ends are left with a 4mm gap from the corresponding edge of the side. The raw material of the blister box is PP transparent engineering plastic. The blister mold is placed in the blister machine, and the blister machine vacuum forms the blister. After cooling and demolding, the blister box 2 is obtained.
[0040] like Figure 2 As shown, the blister box 2 is a square box with an opening at the top and a thickness of 2mm. Two evenly distributed elongated limiting ribs 201 are formed on the inner side wall and bottom wall of the blister box 2. The cross-section of the elongated limiting rib 201 is semi-circular, the width is 4mm, and the height is the same as the thickness of the potting material 3, which is 2mm. The elongated limiting rib 201 is located in the middle of each inner side and does not penetrate the entire surface. The two ends are 4mm away from the corresponding edge of the inner side.
[0041] S2. Potting: Apply silicone oil-based insulating agent to the inner wall of the blister box 2 and the long strip limiting ribs 201. Then place the film capacitor core package 1 into the blister box 2, so that the long strip limiting ribs 201 in the blister box 2 are all abutting against the corresponding side wall of the core package 1. Inject potting material 3 into the space between the blister box 2 and the core package 1. Thermosetting epoxy resin potting material is used. The potting material 3 is liquid at room temperature. After injection, it will fill all the gaps between the core package 1 and the blister box 2. The upper end covers the upper plane of the core package 1 (leaving the capacitor leads) by 2-5mm.
[0042] The setting of the long strip limiting rib 201 ensures that the wall thickness of the potting material 3 wrapped around the outside of the core package 1 is uniform.
[0043] S3. Heat curing: Place the potted product from step S2 into a curing machine for heat curing. The heat curing temperature is 80-90℃ and the heat curing time is 2.5-3.5h. The potting material 3 will wrap and seal the core package 1. The potting material 3 will not stick to the blister box 2. After cooling, the core package 1 encapsulated by the potting material 3 will be removed from the blister box 2. At this time, grooves 301 are left on the outer peripheral sidewall and bottom wall of the potting material layer at the positions corresponding to the limiting ribs 201. Fill each groove 301 with the potting material 3 and heat curing to obtain a finished product of potting material-encapsulated custom film capacitor without plastic shell.
[0044] like Figure 4 As shown, Example 3 is a method for preparing a custom-made film capacitor with a circular blister packaging shell, which includes the following steps:
[0045] S1. Making the blister box: According to the required dimensions of the film capacitor, a circular blister mold is made. The blister mold is made of resin film, and six elongated grooves are evenly distributed on the outer circumference of the blister mold. The elongated grooves are perpendicular to the bottom surface and are located in the middle of the outer circumference. The two ends are 4mm away from the top and bottom edges of the outer circumference. Two circular grooves are set on the bottom surface of the blister mold. The raw material of the blister box is PET transparent engineering plastic. The blister mold is placed in the blister forming machine, and the blister forming machine vacuum forms the blister. After cooling and demolding, the blister box 2 is obtained.
[0046] like Figure 5 As shown, the blister box 2 is an annular U-shaped box with an open top and a thickness of 2mm. Six elongated limiting ribs 201 are evenly distributed in a circle on the inner side wall of the outer periphery of the blister box 2, and two evenly distributed annular limiting ribs 202 are formed on the bottom wall. The cross-section of the elongated limiting ribs 201 and the annular limiting ribs 202 is semi-circular, with a width of 6mm and a height consistent with the thickness of the potting material 3, which is 3mm. The elongated limiting ribs 201 are all located in the middle of the inner side of the outer periphery and do not penetrate the entire surface. The distance between the two ends and the upper and lower edges is 4mm.
[0047] S2. Encapsulation: Place the film capacitor core package 1 into the blister box 2, so that the long strip limiting ribs 201 inside the blister box 2 are all abutting against the corresponding side walls of the core package 1. Inject the encapsulating material 3 into the space between the blister box 2 and the core package 1. The thermosetting epoxy resin encapsulating material is used. The encapsulating material 3 is liquid at room temperature. After injection, it will fill all the gaps between the core package 1 and the blister box 2, and the upper end will cover the upper surface of the core package 1 (leaving the capacitor leads 2-5mm).
[0048] The long strip-shaped limiting rib 201 and the circular ring-shaped limiting rib 202 ensure that the wall thickness of the potting material 3 wrapped around the outside of the core package 1 is uniform.
[0049] S3. Heat curing: The potted product from step S2 is placed in a curing machine for heat curing. The heat curing temperature is 80-90℃ and the heat curing time is 2.5-3.5h. The potting material 3 will wrap and seal the core package 1 and fix the core package 1 to the blister box 2 into an integrated structure to obtain the finished blister plastic shell customized film capacitor.
[0050] like Figure 6 As shown, Example 4 illustrates a method for preparing a custom thin-film capacitor encapsulated in a toroidal, shell-less potting compound, comprising the following steps:
[0051] S1. Making the blister box: According to the required dimensions of the film capacitor, a circular blister mold is made. The blister mold is made of resin film, and six evenly distributed elongated grooves are set on the outer circumference of the blister mold. The elongated grooves are perpendicular to the bottom surface. Two evenly distributed circular grooves are set on the bottom surface of the blister mold. The elongated grooves are located in the middle of the outer circumference. The two ends are 4mm away from the top and bottom edges of the outer circumference. The raw material of the blister box is PET transparent engineering plastic. The blister mold is placed in the blister forming machine, and the blister forming machine vacuum forms the blister. After cooling and demolding, the blister box 2 is obtained.
[0052] like Figure 5 As shown, the blister box 2 is an annular box with an open top and a thickness of 2mm. Six evenly distributed elongated limiting ribs 201 are formed on the inner side wall of the outer circumference of the blister box 2, and two evenly distributed annular limiting ribs 202 are formed on the inner bottom wall. The cross-section of the elongated limiting ribs 201 and the annular limiting ribs 202 is semi-circular, with a width of 6mm and a thickness consistent with the thickness of the potting material 3, which is 3mm. The elongated limiting ribs 201 are located in the middle of the inner side wall of the outer circumference, do not penetrate the entire surface, and are 4mm away from the upper and lower edges of the inner side wall of the outer circumference.
[0053] S2. Potting: Apply silicone oil-based insulating agent to the inner wall of the blister box 2 and each limiting rib. Then, place the film capacitor core package 1 into the blister box 2, so that the long strip limiting ribs 201 in the blister box 2 are all abutting against the corresponding side wall of the core package 1. Inject potting material 3 into the space between the blister box 2 and the core package 1. Thermosetting epoxy resin potting material is used. The potting material 3 is liquid at room temperature. After injection, it will fill all the gaps between the core package 1 and the blister box 2, and the upper end will cover the upper plane of the core package 1 (leaving the capacitor leads) by 2-5mm.
[0054] The long strip-shaped limiting rib 201 and the circular ring-shaped limiting rib 202 ensure that the wall thickness of the potting material 3 wrapped around the outside of the core package 1 is uniform.
[0055] S3. Heat curing: Place the potted product from step S2 into a curing machine for heat curing. The heat curing temperature is 80-90℃ and the heat curing time is 2.5-3.5h. The potting material 3 will wrap and seal the core package 1. The potting material 3 will not stick to the blister box 2. After cooling, the core package 1 encapsulated by the potting material 3 will be removed from the blister box 2. At this time, grooves 301 are left on the outer circumferential surface and bottom surface of the potting material layer at the corresponding positions of each limiting rib. Fill each groove 301 with the potting material 3 and heat curing to obtain a ring-shaped, shell-free potting material-encapsulated custom film capacitor finished product.
[0056] This utility model embodiment uses a blister box method. The blister mold for preparing the blister box can be made of resin mold, wood mold, or plaster mold. It is efficient, generally completed in 1 day, and low in cost, generally between 200 and 300 yuan. Various shapes can be formed, such as the square shapes in embodiments 1 and 2, and the circular shapes in embodiments 3 and 4. In contrast, injection molds take 30 to 40 days, have a rather complex structure, and cost between 200,000 and 500,000 yuan.
[0057] The above are merely preferred embodiments of this utility model. It should be noted that, for those skilled in the art, several improvements and substitutions can be made without departing from the technical principles of this utility model, and these improvements and substitutions should also be considered within the protection scope of this utility model.
Claims
1. A custom-made film capacitor with a non-injection-molded plastic shell, characterized in that: There are two types: one is a custom film capacitor with encapsulant without a plastic shell, and the other is a custom film capacitor with a blister-formed plastic shell. The custom film capacitor with encapsulant without a plastic shell includes a custom film capacitor core and an encapsulant layer. The custom film capacitor with a blister-formed plastic shell includes a custom film capacitor core, an encapsulant layer, and a blister box. The blister box is prepared using existing blister forming technology. The encapsulant layer is formed by encapsulating the core using the blister box and is wrapped around the outer wall of the core. The shape of the encapsulant layer and the blister box are consistent with the shape of the core and the wall thickness is uniform.
2. The custom-made film capacitor without injection molding and with a plastic shell according to claim 1, characterized in that: The potting compound layer is made of thermosetting epoxy resin with a thickness of 2-5 mm.
3. A custom-made film capacitor without injection molding and with a plastic shell according to claim 1, characterized in that: The blister pack is made of one of the following transparent engineering plastics: PET, PP, or PVC, with a thickness of 1–2 mm.
4. A custom-made film capacitor without injection molding and with a plastic shell according to claim 1, characterized in that: The custom film capacitor can be any shape required by the customer.