A method for manufacturing a large-capacity thin film capacitor using a core in parallel

Abstract

The application relates to the technical field of thin-film capacitors, in particular to a large-capacity thin-film capacitor preparation method adopting core parallel connection. The capacitor is composed of a plurality of cores, the upper electrodes of the cores are connected in parallel through positive copper bars, and the lower electrodes are connected in parallel through negative copper bars; the core is a core rod formed by wrapping a metalized polypropylene film, the positive copper bar and the negative copper bar are provided with a bonding area corresponding to the end face of the core rod, and the positive copper bar and the negative copper bar are connected with the end face of the core rod through a gold spraying layer covering the bonding area. Compared with the prior art, the application adopts the mode of assembling first and then spraying gold, the metal layer is covered on the capacitor core and the copper bar to lead out the core electrode, the metal layer can effectively diffuse and fill the gap caused by the individual difference of the copper bar and the core, the contact area of the core and the copper bar is increased, the reliability of the connection between the copper bar and the core is ensured, and thus the occurrence of conditions such as incomplete welding, virtual welding and welding separation can be effectively prevented.

Description

Technical Field

[0001] This invention relates to the field of thin-film capacitor technology, and more specifically, to a method for manufacturing a large-capacity thin-film capacitor using parallel connection of cores. Background Technology

[0002] Due to their inherent advantages, film capacitors have been widely used in many fields such as new energy vehicles, photovoltaic power generation, and wind power generation. Currently, due to the large demand for film capacitor capacity, multiple film capacitors are connected in parallel or series to combine multiple film capacitors into a supercapacitor in the production and manufacturing of film capacitors.

[0003] Currently, the purpose of the "gold spraying process" in the manufacturing of thin-film capacitors is to spray highly conductive, low-melting-temperature tin-zinc metal particles onto both ends of the wound and shaped core (generally using electro-spraying, i.e., using a high-current fuse, compressed air is used to break up the molten metal and blow it out at high speed to cover the end faces of the capacitor core in a particle state), facilitating the connection of electrodes via current welding or soldering. However, the lead-out of the capacitor core assembly of a supercapacitor requires multiple current welding or soldering operations to complete.

[0004] Taking the common MKP86 capacitor core lead-out as an example, see... Figures 12 to 15 As shown, two welding heads are pressed against the solder joint, causing the capacitor core and copper busbar to adhere to each other at the solder joint, forming a contact resistance. Current then flows between the welding heads, generating heat. This heat melts the metal layer covering the capacitor core, connecting the core to the copper busbar. To ensure welding reliability, each core needs to be welded twice. Since this type of capacitor consists of six cores, 12 welding steps are required to complete the welding of the capacitor core assembly to the copper busbar on one side. The welding of the other side also needs to repeat this process. A total of 24 welding steps are required to combine the copper busbar and the capacitor core assembly on both sides. This results in low welding efficiency and an excessively long manufacturing cycle.

[0005] Furthermore, capacitor cores within a capacitor bank may exhibit inconsistent heights, creating gaps when bonded to the copper busbar. If these gaps are excessive and the deformation of the copper busbar cannot compensate for them, the relatively uniform welding pressure can prevent the copper busbar and core from fully adhering, leading to abnormal solder joints such as cold solder joints, detachment, or excessively deep welds. Regardless of whether machine spot welding or manual welding is used, the inconsistent bonding resistance between the copper busbar and each capacitor core results in unstable current flow during welding, excessively high welding temperatures, and issues such as burns to the core end faces and significant wear on individual cores. These problems are difficult to detect and eliminate, potentially leading to the failure of the entire capacitor bank due to thermal breakdown of individual capacitors. Summary of the Invention

[0006] The purpose of this invention is to provide a method for manufacturing a large-capacity thin-film capacitor using parallel cores. By assembling first and then spraying gold, a metal layer is used to cover the capacitor core and copper busbar, making them a whole, thereby eliminating the original multiple welding processes and overcoming the defects pointed out in the background art.

[0007] The embodiments of the present invention are achieved through the following technical solution: a large-capacity thin-film capacitor using parallel cores, the capacitor being composed of several cores, the upper electrodes of the several cores being connected in parallel through a positive copper busbar, and the lower electrodes being connected in parallel through a negative copper busbar; The core is a core rod formed by wrapping a metallized polypropylene film. The positive and negative copper busbars have bonding areas on the end faces of the core rod, and the positive and negative copper busbars are connected to the end faces of the core rod through a gold sputtering layer covering the bonding areas.

[0008] According to a preferred embodiment, the thickness of the positive electrode copper busbar and the negative electrode copper busbar is 0.5-0.7 mm.

[0009] According to a preferred embodiment, the thickness of the gold-plated layer is 0.5-0.7 mm.

[0010] According to a preferred embodiment, the area of ​​the bonding region is smaller than the end face area of ​​the mandrel.

[0011] The present invention also provides a method for preparing a large-capacity thin-film capacitor as described above, comprising the following steps: a. A capacitor core assembly is formed by combining and positioning several prepared cores that have not been gold-plated on their end faces using an insulating medium; b. Make the upper end face of the capacitor core group contact the bonding area on the positive copper busbar, and the lower end face contact the bonding area on the negative copper busbar. Wrap the capacitor core group and copper busbar with an insulating medium to position them and expose the bonding area. c. Cover the exposed bonding area with a gold spray layer, and use the gold spray layer to lead out the upper electrode of the core in the capacitor core assembly as the positive electrode, and lead out the lower electrode of the core in the capacitor core assembly as the negative electrode. d. Stripping the insulating medium, the capacitor core assembly is connected in parallel with the positive electrode at the top via a positive copper busbar, and in parallel with the negative electrode at the bottom via a negative copper busbar, to form the large-capacity film capacitor.

[0012] According to a preferred embodiment, in step c, a gold spraying layer is applied to the exposed bonding area using a gold spraying machine, and then cooled using compressed air.

[0013] According to a preferred embodiment, a gold spray layer is applied to the exposed bonding area by brushing and then cured at a temperature of less than 100°C.

[0014] The technical solution of this invention has at least the following advantages and beneficial effects: Compared with the prior art, this invention adopts a method of first assembling and then spraying gold, using a metal layer to cover the capacitor core and copper busbar to lead out the core electrodes. The metal layer can effectively diffuse and fill the gaps caused by individual differences between the copper busbar and the core, increasing the contact area between the core and the copper busbar, ensuring the reliability of the connection between the copper busbar and the core, thereby effectively preventing the occurrence of incomplete soldering, cold soldering, and desoldering. This invention has the following characteristics: simple manufacturing process, easy for large-scale mass production; improved production efficiency, shortened manufacturing cycle, and greatly reduced production costs; effectively prevented the occurrence of incomplete soldering, cold soldering, and desoldering, resulting in high capacitor safety and reliability. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the capacitor core assembly and positioning process provided in Embodiment 3 of the present invention; Figure 2 This is a schematic diagram of the capacitor core assembly and copper busbar assembly process provided in Embodiment 3 of the present invention; Figure 3 This is a schematic diagram of the capacitor core assembly and copper busbar winding and positioning process provided in Embodiment 3 of the present invention; Figure 4 This is a schematic diagram of the simultaneous processing of multiple capacitor core groups provided in Embodiment 3 of the present invention; Figure 5 and Figure 6 This is a schematic diagram of the gold spraying process provided in Embodiment 3 of the present invention; Figure 7 and Figure 8 This is a schematic diagram of the gold plating effect on the capacitor core assembly provided in Embodiment 3 of the present invention; Figure 9 This is a schematic diagram of the capacitor core assembly after the stripping of the insulating dielectric provided in Embodiments 1 and 3 of the present invention; Figure 10 This is a schematic diagram of the filling of the bonding region by the metal layer provided in Embodiments 2 and 3 of the present invention; Figure 11 This is a schematic diagram of the copper busbar structure provided in Embodiment 2 of the present invention; Figure 12 A schematic diagram of the capacitor core assembly of the MKP86 capacitor provided for the background art; Figure 13 An exploded view of the capacitor core assembly of the MKP86 capacitor provided for the background technology. Figure 14 A schematic diagram of the welding of the capacitor core assembly of an MKP86 capacitor provided for the background art. Figure 15 A schematic diagram of the solder joints of the MKP86 capacitor core assembly provided for the background technology. Figure 16 This is a flowchart of capacitor manufacturing process provided in Embodiment 3 of the present invention; Icons: 1-Core, 2-Positive copper busbar, 3-Negative copper busbar, 4-Connection area, 5-Gold plating layer, 6-Insulating medium, 7-Nozzle. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0017] Example 1 like Figure 9 As shown, this embodiment provides a large-capacity film capacitor with parallel cores. The capacitor is composed of several cores 1, and the specific number of cores 1 is determined by the capacitor capacity requirement and is not limited thereto. Specifically, in this embodiment, in order to make the comparison between the capacitor provided in this embodiment and the capacitor core group of the MKP86 capacitor mentioned in the background art more intuitive, the number of cores 1 in this embodiment is set to 6.

[0018] Furthermore, in this embodiment, the upper electrodes of the plurality of cores 1 are connected in parallel via positive copper busbars 2, and the lower electrodes are connected in parallel via negative copper busbars 3. Specifically, the core 1 is a core rod formed by wrapping a metallized polypropylene film. The positive copper busbars 2 and negative copper busbars 3 have bonding regions 4 on the end faces of the core rod corresponding to the end faces of the core rod. The positive copper busbars 2 and negative copper busbars 3 are connected to the end faces of the core rod through a gold sputtering layer 5 covering the bonding regions 4. It should be noted that in this embodiment, the gold sputtering layer 5 covering the bonding regions 4 is made of micron-sized tin-zinc metal particles with high conductivity and low melting temperature. By covering the bonding regions 4 with metal particles, they are made into a whole, thereby achieving the purpose of leading out the electrodes of the core 1.

[0019] Furthermore, in this embodiment, the thickness of the positive electrode copper busbar 2 and the negative electrode copper busbar 3 is 0.5-0.7 mm. Furthermore, in one embodiment of this invention, the thickness of the gold plating layer 5 is the same as the thickness of the copper busbar, both being 0.5-0.7 mm.

[0020] This invention employs a pre-assembly followed by gold spraying method, utilizing a metal layer to cover the capacitor core 1 and the copper busbar to lead out the electrodes of the core 1. The metal layer can effectively diffuse and fill the gaps caused by individual differences between the copper busbar and the core 1, increasing the contact area between the core 1 and the copper busbar, ensuring the reliability of the connection between the copper busbar and the core 1, thereby effectively preventing the occurrence of incomplete soldering, cold soldering, and desoldering.

[0021] Example 2 Unlike the previous embodiment, this embodiment improves the structure of the copper busbar based on Embodiment 1 to ensure the gold plating effect, as detailed below: See Figure 11 The bonding area 4 consists of a square hole and multiple layers of L-shaped holes located on the outer sides of the four corners of the square hole. Specifically, in this embodiment, there are two layers of L-shaped holes, and the L-shaped holes at different corners are not connected to each other. See also Figure 10 As shown, the above structure increases the bonding area between the copper busbar and the end face of core 1. After the copper busbar and core 1 are bonded together, sufficient space for metal particles to accumulate is provided. The larger the accumulation space, the stronger the bond stability. It should be noted that this embodiment does not impose specific restrictions on the cutting method of the bonding area 4. The cutting size is different for different specifications of capacitors and is determined by the end face area of ​​a single core 1. As long as the area of ​​the bonding surface is smaller than the end face area of ​​the core rod, it is acceptable. This will not be elaborated further here.

[0022] Example 3 See Figure 16 As shown, this embodiment provides a method for preparing a large-capacity thin-film capacitor as described above, including the following steps: a. See also Figure 1 As shown, several prepared cores 1 that have not been gold-plated on their end faces are combined and positioned by winding through the insulating medium 6 to form a capacitor core assembly, which is convenient for subsequent assembly with copper busbars; it should be noted that the insulating medium 6 used in this embodiment is insulating tape.

[0023] b. See also Figure 2 As shown, the upper end face of core 1 in the capacitor core assembly is in contact with the bonding area 4 on the positive copper busbar 2, and the lower end face is in contact with the bonding area 4 on the negative copper busbar 3; further, see... Figure 3 As shown, the capacitor core assembly and copper busbar are wrapped and positioned by insulating tape to form a single component, exposing the bonding area 4 on the single component.

[0024] c. See also Figure 4 As shown, place the multiple individually wound components into the tray of the gold spraying machine, keeping them perpendicular to the nozzle 7; further, see... Figure 5 and Figure 6 As shown, the gold spraying machine is started, and the nozzle 7 scans and moves along the X and Y axes to spray a layer of gold 5 onto the exposed bonding area 4. Compressed air is used to cool it, and the spraying thickness is consistent with the copper busbar thickness. (See also...) Figure 7 and Figure 8 As shown, after one side is coated, the component is flipped over to be coated on the other side. After coating, each component is covered with a 0.5-0.7mm metal layer.

[0025] d. See also Figure 9As shown, the components are removed from the tray, and the insulating tape is peeled off. At this point, the sprayed metal layer firmly bonds the core 1 to the copper busbar, thus completing the electrode lead-out of the capacitor core assembly. It should be noted that the upper electrode of the core 1 in the capacitor core assembly is led out as the positive electrode through the gold spray layer 5, and the lower electrode of the core 1 in the capacitor core assembly is led out as the negative electrode, realizing the electrode lead-out of each core 1. The upper positive electrode of the capacitor core assembly is connected in parallel through the positive copper busbar 2, and the lower negative electrode is connected in parallel through the negative copper busbar 3, forming the large-capacity film capacitor.

[0026] See Figure 10 As shown, it should be noted that because the sprayed metal particles are micron-sized, under the cooling effect of compressed air, they can effectively diffuse and fill the gaps caused by individual differences between the copper busbar and core 1. The accumulation and superposition of multiple layers of metal particles increases the contact area between core 1 and the copper busbar, ensuring a reliable connection between the copper busbar and core 1. In addition, since the sprayed metal particles are dispersed by compressed air after the metal has melted and then sprayed onto the copper busbar and core 1, the metal particles covering the copper busbar and core 1 are rapidly cooled under the action of compressed air, thus avoiding the generation of local high temperatures that could burn the end film of core 1. Moreover, since the sprayed metal particles move and cover in a circular pattern, it is equivalent to uniformly covering multiple solder joints, thus avoiding the local temperature rise at solder joints, end film burns, and increased capacitor losses that occur with resistance welding and tin soldering.

[0027] Example 4 Unlike the gold spraying method provided in Example 3, this embodiment of the invention uses a brushing method. A 0.5mm-0.7mm thick layer of micron-level tin-zinc metal particle adhesive paste with high conductivity and low melting temperature is applied to the original spraying bonding area 4 and then cured to achieve the connection between the copper busbar and the core 1.

[0028] Furthermore, since the curing temperature is <100℃, it will not produce the localized temperature rise at the solder joint, burns on the end film, or increased capacitor loss that occur with resistance welding and tin soldering.

[0029] Example 5 Unlike the spraying method provided in Example 3 and the brushing method provided in Example 4, this example uses laser welding and is used in conjunction with a compressed air cooling device. Multiple wound single components are placed on the laser welding platform for multi-point scanning welding. At the same time, the compressed air device is added for cooling to avoid the welding temperature being too high and burning the film at the core 1 end.

[0030] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating a large-capacity thin-film capacitor using parallel connection of cores, characterized in that, The capacitor is composed of several cores (1). The upper electrodes of the several cores (1) are connected in parallel through positive copper busbars (2), and the lower electrodes are connected in parallel through negative copper busbars (3). The core (1) is a core rod formed by wrapping a metallized polypropylene film. The positive copper busbars (2) and negative copper busbars (3) are provided with a bonding area (4) on the end face of the core rod. The positive copper busbars (2) and negative copper busbars (3) are connected to the end face of the core rod through a gold sputtering layer (5) covering the bonding area (4). The thickness of the positive copper busbars (2) and negative copper busbars (3) is 0.5-0.7 mm, the thickness of the gold sputtering layer (5) is 0.5-0.7 mm, and the area of ​​the bonding area (4) is smaller than the end face area of ​​the core rod. The preparation method includes the following steps: a. A number of prepared cores (1) that have not been gold-plated on their end faces are combined and positioned by means of an insulating medium (6) to form a capacitor core group; b. The upper end face of the core (1) in the capacitor core group is in contact with the bonding area (4) on the positive copper busbar (2), and the lower end face is in contact with the bonding area (4) on the negative copper busbar (3). The capacitor core group and the copper busbar are wound and positioned by the insulating medium (6), and the bonding area (4) is exposed. c. Cover the exposed bonding area (4) with a gold sputtering layer (5), and through the gold sputtering layer (5), lead out the upper electrode of the core (1) in the capacitor core assembly as the positive electrode, and lead out the lower electrode of the core (1) in the capacitor core assembly as the negative electrode. d. Strip the insulating medium (6), and the capacitor core group is connected in parallel at the upper positive terminal through the positive copper busbar (2) and at the lower negative terminal through the negative copper busbar (3) to form the large-capacity film capacitor.

2. The method for preparing a large-capacity thin-film capacitor as described in claim 1, characterized in that, In step c, a gold spraying layer (5) is applied to the exposed bonding area (4) using a gold spraying machine, and compressed air is used to cool it.

3. The method for preparing a large-capacity thin-film capacitor as described in claim 2, characterized in that, A gold spray layer (5) is applied to the exposed bonding area (4) by brushing and then cured at a temperature of less than 100°C.

Images