Preparation method for busbar assembly, busbar assembly, and battery module

Abstract

The present application relates to the technical field of batteries. Provided are a preparation method for a busbar assembly, a welding method, and a battery module. The preparation method comprises sequentially stacking a first insulating layer, a busbar, a flexible circuit board and a second insulating layer, and then laminating and pre-fixing same to form an assembly to be fixed; and placing said assembly into an SMT process line, and performing component attachment, hot pressing and welding fixation on said assembly to prepare a busbar assembly. In the present application, by performing, in an SMT process line, component attachment on a flexible circuit board, hot pressing on a multilayer structure, and welding fixation, production steps are reduced and the production efficiency is improved.

Description

Busbar assembly fabrication method, busbar assembly and battery module

[0001] This application claims priority to Chinese patent applications filed on November 26, 2024, with application numbers 202411712754.X and 202422901353.0, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, and in particular to a method for preparing a busbar assembly, the busbar assembly, and a battery module. Background Technology

[0003] The battery module comprises multiple individual battery modules, which are electrically connected via a busbar. These individual battery modules utilize a flexible circuit board to collect voltage and temperature signals within the module. In related technologies, the busbar assembly includes a busbar, a flexible circuit board, and upper and lower insulating plates, with the busbar and flexible circuit board positioned between the upper and lower insulating plates. Before being placed between the upper and lower insulating plates, the flexible circuit board undergoes surface mount technology (SMT) to solder components onto it. Subsequently, the busbar and flexible circuit board are soldered together, followed by processes such as adhesive application and lamination of the insulating plates. Finally, the busbar, flexible circuit board, and upper and lower insulating plates are stacked to form the busbar assembly. Invention Overview

[0004] The busbar assembly manufacturing method used in related technologies requires multiple welding, pressing, and gluing processes, resulting in high manufacturing costs and reduced production efficiency.

[0005] In a first aspect, this application provides a method for manufacturing a busbar assembly, the method comprising:

[0006] The first insulating layer, busbar, flexible circuit board and second insulating layer are stacked sequentially.

[0007] The first insulating layer, the busbar, the flexible circuit board, and the second insulating layer, which are stacked together, are laminated and pre-fixed to form the component to be fixed.

[0008] The component to be fixed is placed in the SMT process line, and the component to be fixed is subjected to component mounting, hot pressing and soldering to obtain the bus assembly.

[0009] Secondly, this application provides a bus assembly, which is manufactured by the method for preparing a bus assembly as described in the first aspect, and the bus assembly includes:

[0010] The first and second insulating layers are arranged opposite to each other;

[0011] A busbar is disposed between the first insulating layer and the second insulating layer;

[0012] A flexible circuit board is disposed between the busbar and the first insulating layer;

[0013] The flexible circuit board has a closed outer edge and covers the busbar. The flexible circuit board has multiple cutouts that expose the positive and negative portions of the busbar.

[0014] Thirdly, this application provides a battery module including a plurality of individual cells and a bus assembly as described in the second aspect. The plurality of individual cells are arranged along the length direction and the width direction, and adjacent individual cells are staggered along the width direction. All of the plurality of individual cells are connected to the bus. Beneficial effects

[0015] In this application, by stacking a first insulating layer, a busbar, a flexible circuit board, and a second insulating layer together and placing them on an SMT process line, the component mounting, multi-layer hot pressing, and soldering of the flexible circuit board are achieved within a single SMT process line. This saves production steps, improves production efficiency, and can also reduce the investment in soldering and hot pressing equipment on the production line to a certain extent, thus helping to reduce costs. Specifically, firstly, the first insulating layer, busbar, flexible circuit board, and second insulating layer are sequentially stacked to form a pre-assembled stack, which serves as the precursor to the busbar assembly. Then, this stack is laminated and fixed to form the assembly to be fixed, ensuring the stability of the stack in subsequent processes. Finally, the assembly to be fixed is placed on the SMT process line for component mounting, hot pressing, and soldering to obtain the busbar assembly. The entire surface mount, hot pressing, and soldering process is completed in one SMT process line. Compared with related technologies, which require a separate SMT process for the flexible circuit board for surface mount, followed by soldering the flexible circuit board and bus, and then stacking the insulating board, bus, and flexible circuit board for hot pressing, the preparation process of this application is simpler. Moreover, the process line used is only an SMT process line for component mounting on the flexible circuit board, without the need for additional processes or equipment, which helps to save costs. Attached Figure Description

[0016] Figure 1 is a flowchart illustrating a method for fabricating a busbar assembly provided in this application;

[0017] Figure 2 is an exploded view of a battery module provided in this application;

[0018] Figure 3 is a structural schematic diagram of a bus assembly provided in this application;

[0019] Figure 4 is a schematic diagram of the explosion in Figure 3;

[0020] Figure 5 is a schematic diagram of the structure of a flexible circuit board in a bus assembly provided in this application;

[0021] Figure 6 is a schematic diagram of the bus structure in a bus assembly provided in this application;

[0022] Figure 7 is a schematic diagram of the structure of a busbar assembly provided in this application.

[0023] Explanation of reference numerals in the attached figures:

[0024] 1-Single cell; 2-Bus assembly; 21-First insulating layer; 22-Second insulating layer; 23-Busbar; 231-Bustable piece; 2311-First sub-piece; 23111-Positive electrode connection; 23112-Negative electrode connection; 23113-Welding bump; 23114-Positive electrode positioning notch; 23115-Negative electrode positioning notch; 2312-Second sub-piece; 2313-Inclined section; 232-Positive electrode busbar; 233-Negative electrode busbar; 234-Positive electrode plate; 235-Negative electrode plate; 236-Intermediate busbar; 24-Flexible circuit board; 241-Circuit board body; 2411-Koilout assembly; 24111-First through hole; 24112-Second through hole; 242-Support plate; 243-Solder point; 244-Connector. Embodiments of the present invention

[0025] Please refer to Figure 1. An embodiment of this application provides a method for fabricating a busbar assembly, including:

[0026] S1. The first insulating layer, busbar, flexible circuit board and second insulating layer are stacked sequentially.

[0027] S2. The first insulating layer, busbar, flexible circuit board and second insulating layer are laminated and pre-fixed to form the assembly to be fixed;

[0028] S3. Place the component to be fixed into the SMT process line, perform component mounting, hot pressing and soldering to fix the component to be fixed, and obtain the bus assembly.

[0029] The technical solution provided in this application stacks a first insulating layer, a busbar, a flexible circuit board, and a second insulating layer together and places them on an SMT process line. This allows for component mounting, multi-layer hot pressing, and soldering of the flexible circuit board within a single SMT process line, saving production steps, improving production efficiency, and reducing investment in soldering and hot pressing equipment, thus lowering costs. Specifically, the process involves firstly stacking the first insulating layer, busbar, flexible circuit board, and second insulating layer sequentially to form a pre-assembled stack, which serves as the precursor to the busbar assembly. This stack is then laminated and fixed to form the assembly to be fixed, ensuring the stability of the stack in subsequent processes. Finally, the assembly to be fixed is placed on the SMT process line for component mounting, hot pressing, and soldering to obtain the busbar assembly. The entire surface mount, hot pressing, and soldering process is completed in one SMT process line. Compared with related technologies, which require a separate SMT process for the flexible circuit board for surface mount, followed by soldering the flexible circuit board and bus, and then stacking the insulating board, bus, and flexible circuit board for hot pressing, the preparation process of this application is simpler. Moreover, the process line used is only an SMT process line for component mounting on the flexible circuit board, without the need for additional processes or equipment, which helps to save costs.

[0030] For step S1: the first insulating layer, busbar, flexible circuit board, and second insulating layer are stacked sequentially. This is mainly to allow the first insulating layer, busbar, flexible circuit board, and second insulating layer to be combined into a whole, facilitating subsequent overall welding and hot pressing processes. In addition, it should be noted that during the stacking of the first insulating layer, busbar, flexible circuit board, and second insulating layer, positioning is performed first. This positioning is generally completed during the fabrication of the first insulating layer, second insulating layer, busbar, and flexible circuit board.

[0031] In detail, the first insulating layer, the second insulating layer, the busbar, and the flexible circuit board are all integrally formed by stamping using their respective unique molds. This improves the strength of each layer and prepares for subsequent unified welding and hot pressing processes. The first and second insulating layers are stamped using molds with the same outline dimensions, ensuring that the edge outlines of the first and second insulating layers can overlap and align. The first and second insulating layers are stamped into a plate shape, with multiple holes formed in their plate structure to expose a portion of the busbar located between the first and second insulating layers, facilitating contact between the individual cells and the busbar. In addition, multiple positioning grooves are formed on the first insulating layer. The positive, negative, intermediate, positive, and negative electrode plates of the busbar are respectively positioned in their corresponding positioning grooves. Multiple busbar segments are aligned with the holes, with one busbar aligned with two holes. The busbar segments are stepped, allowing the edges of the holes to form positioning and limiting functions for the busbar segments. Correspondingly, through holes are formed on the flexible circuit board, and holes are formed on the second insulating layer. By using through holes and holes for stacking positioning, the correct position of the first insulating layer, the second insulating layer, the busbar, and the flexible circuit board can be ensured as much as possible.

[0032] In some embodiments, prior to step S1, i.e., before the step of sequentially stacking the first insulating layer, busbar, flexible circuit board, and second insulating layer, the method further includes:

[0033] Apply solder paste to the side of the bus facing the flexible circuit board and / or the side of the flexible circuit board facing the bus.

[0034] Solder paste is applied to the side of the busbar facing the flexible circuit board. The solder paste can be applied to the entire surface or at fixed points. In this embodiment, fixed-point application is used to avoid the solder paste on the busbar affecting the normal operation of the flexible circuit board and the conductive contact between the busbar and the individual cells. Specific fixed points can be pre-positioned on the busbar or on the flexible circuit board, such as marking the flexible current board. These marks indicate the positions where the solder paste is applied, and after subsequent soldering, the marked locations become the solder joints. Of course, in other embodiments, solder paste can also be applied to the side of the flexible circuit board facing the busbar, specifically at the pre-positioned locations, or the solder paste can be applied to both the busbar and the flexible circuit board; there is no limitation on this method.

[0035] It should be noted that the solder paste is mainly applied using screen printing. The specific printing process is a standard procedure in this field and will not be described in detail here.

[0036] In this embodiment, the coating material is solder paste, primarily because it has a low melting point, making it suitable for reflow soldering. In the reflow soldering process, the solder paste is uniformly soldered in a reflow oven, forming a high-strength connection. Furthermore, the good conductivity and oxidation resistance of the solder paste ensure the conductivity of the connection and prevent oxidation, thus extending the solder joint's lifespan.

[0037] Correspondingly, the bus is made of nickel because nickel has good electrical conductivity and is very suitable for soldering with solder paste.

[0038] In some embodiments, prior to step S1, i.e., before the step of sequentially stacking the first insulating layer, busbar, flexible circuit board, and second insulating layer, the method further includes:

[0039] Apply adhesive to the side of the first insulation layer facing the busbar;

[0040] Adhesive is applied to the side of the second insulating layer facing the flexible circuit board.

[0041] Applying adhesive to the first and second insulating layers is mainly to prepare for subsequent hot pressing. Applying adhesive in advance not only facilitates the overall hot pressing of the subsequent SMT process, but also plays a preliminary role in fixing the lamination of the first insulating layer, busbar, flexible circuit board, and second insulating layer before entering the SMT process line.

[0042] It should be noted that the steps of applying adhesive to the side of the first insulating layer facing the bus and applying adhesive to the side of the second insulating layer facing the flexible circuit board are not sequential with the steps of applying solder paste to the side of the bus facing the flexible circuit board and / or the side of the flexible circuit board facing the bus. Either step can be performed first, or they can be performed simultaneously, as each step is independent.

[0043] In some embodiments, step S3, namely the step of placing the component to be fixed into the SMT process line, performing component mounting, hot pressing, and soldering to fix the component to be fixed to obtain the bus assembly, specifically includes:

[0044] S31. Place the component to be fixed into the SMT process line and mount the components on the flexible circuit board in the component to be fixed.

[0045] Specifically, a pick-and-place machine mounts components one by one onto a flexible circuit board according to a preset programming program. During high-speed operation, the pick-and-place machine automatically calibrates based on component size and placement position, ensuring precise placement of components on the flexible circuit board. Simultaneously, buses enter the mounting process along with the flexible circuit board. The pick-and-place machine places the buses in their predetermined soldering positions on the flexible circuit board according to programming instructions, physically fixing the bus and flexible circuit board together, laying the foundation for subsequent soldering and thermoforming.

[0046] The flexible circuit board comprises a circuit board body and a connector. The circuit board body is equipped with temperature and voltage sensors and is electrically connected to the connector to enable real-time acquisition and transmission of key parameters of the battery module, such as voltage and temperature. The circuit board body covers the positive and negative terminals of the busbar and exposes the positive and negative terminals through multiple cutouts, facilitating subsequent electrical connections. The circuit board body is made of a flexible and conductive material, such as polyimide or other suitable flexible substrates, ensuring its flexible placement within the complex space of the battery module.

[0047] To monitor the operating status of the battery module, a temperature sensor (not shown in the figure) and a voltage sensor (not shown in the figure) are integrated on the circuit board. These sensors are located at different positions on the circuit board to collect temperature and voltage signals from the battery module. In practical applications, the temperature sensor can be placed near the current channel of the battery module to accurately monitor the heat generated by the busbar and individual cells during operation. The voltage sensor is placed at key nodes of the battery module to detect the voltage changes of each individual cell in real time.

[0048] The connector is located at one end of the circuit board and is electrically connected to the temperature and voltage sensors on the board. Through this connector, the acquired voltage and temperature signals can be transmitted to an external control system or battery management system (BMS). The connector can employ a standard multi-pin design to ensure a stable electrical connection and support high-speed data transmission. The choice of material for connector 244 is also crucial; its housing should possess high durability and anti-interference performance to ensure that sensor data transmission is unaffected by electromagnetic interference or environmental factors.

[0049] S32. Reflow soldering is performed on the components to be fixed with mounted components.

[0050] The entire assembly to be fixed is placed in a reflow oven, where the solder paste gradually melts at an appropriate temperature, completing the soldering of the components to the flexible circuit board. Simultaneously, at the high temperature of the reflow oven, the solder paste melts and forms solder joints with the bus and the flexible circuit board, achieving electrical connection. The nickel material of the bus bonds well with the solder paste, resulting in good solder strength and ensuring sufficient current carrying capacity.

[0051] In some embodiments, the step of reflow soldering the assembly to be fixed with mounted components specifically includes:

[0052] Place the component to be fixed with the mounted components into the reflow oven;

[0053] The temperature in the reflow oven is controlled to melt the solder paste used for soldering, thereby completing the soldering of components to the flexible circuit board and the soldering of the flexible circuit board to the bus.

[0054] Furthermore, the reflow oven is equipped with a temperature profile, which includes a preheating section, a reflow section, and a cooling section. The temperature range of the preheating section is 100℃-180℃, the temperature range of the reflow section is 230℃-250℃, and the temperature range of the cooling section is 0℃-100℃.

[0055] In detail, after the components to be fixed enter the reflow oven, the flexible circuit board and components are slowly heated to a certain temperature. In this embodiment, the temperature range is 150°C to 180°C to ensure uniform temperature of the components to be fixed. The heating rate of the preheating section is controlled at 1-3°C / second to prevent uneven heating of the flexible circuit board and components, which could cause thermal stress and damage to components or solder paste splatter. The heating time of the preheating section can be set to 60-120 seconds to ensure that the busbar, flexible circuit board, and components reach a suitable temperature, providing sufficient time for the activation of the flux added to the solder paste.

[0056] After the preheating stage, the reflow stage begins. Specifically, compared to the preheating stage, the temperature in the reflow stage rises rapidly to the melting point of solder (the melting point of solder ranges from 230-250℃, the exact temperature depending on whether it's lead-free or lead-containing solder paste). The solder paste completely melts, making contact with the soldering surfaces of the components and forming a strong bond. The reflow stage time is controlled between 30-60 seconds to avoid overheating, which could damage components or make the solder joints brittle. It should be noted that the reflow temperature for lead-free solder paste is controlled between 240℃ and 245℃, while the reflow temperature for lead-containing solder paste is controlled between 220℃ and 230℃.

[0057] After the reflow section, the circuit board enters the cooling section. After passing through the peak temperature zone, the flexible circuit board rapidly enters the cooling section for cooling, gradually reducing the temperature to room temperature at a rate of 4°C / second. This slow cooling allows the solder joints to gradually solidify, forming a stable metal bond and avoiding stress and solder joint cracks caused by excessively rapid cooling. Ensuring a stable temperature change in the cooling section prevents thermal stress on the solder joints, which could lead to welding defects such as cracks and incomplete solder joints.

[0058] The temperature profile for reflow soldering is divided into three stages: preheating, reflow, and cooling. In the preheating stage, the heating rate is controlled to ensure the circuit board and components heat up gradually, avoiding temperature stress caused by excessively rapid heating. In the reflow stage, an appropriate peak temperature and holding time are set to ensure the solder paste melts completely and makes full contact with the preset solder joint positions, ensuring solder strength. In the cooling stage, the cooling rate is appropriately controlled to prevent stress cracking of the solder joints due to excessively rapid cooling.

[0059] Furthermore, in some embodiments, the temperature profile includes a holding period in addition to the three time segments mentioned above. This holding period is located between the preheating and reflow stages. During this temperature segment, the preset solder joint locations and the solder paste temperature are maintained within a high range. In this embodiment, the temperature range is 180°C to 200°C. The flux is fully activated during this stage, removing oxides from the solder joint surface and enhancing the soldering effect. The holding period allows the temperature of the flexible circuit board and components to gradually become uniform, and the activation effect of the flux effectively removes oxides, thus ensuring the subsequent soldering quality. The holding period lasts for 90-120 seconds to ensure that the active ingredients of the solder paste fully exert their function and achieve a good wetting effect.

[0060] S33. The components to be fixed after reflow soldering are hot-pressed together to obtain the busbar assembly.

[0061] Specifically, before hot pressing, the first insulating layer, busbar, flexible circuit board, and second insulating layer are sequentially stacked and accurately aligned. This part of the process is completed in steps S1 and S2, ensuring the precise positioning of the solder joints, contact points, and insulating layers. After stacking and alignment, the components to be fixed are cleaned and inspected to ensure that the surfaces of each layer are free of dust or impurities, especially the solder joint area between the busbar and the flexible circuit board, to avoid affecting the bonding effect or causing electrical faults.

[0062] The hot pressing temperature range of the hot press equipment is preset to 150℃ to 180℃ to ensure that the adhesive melts completely at this temperature without excessive carbonization. The hot pressing pressure range of the hot press equipment is preset to 0.3MPa to 1.5MPa to ensure uniform bonding of each layer without damaging the flexible circuit board or other components. The hot pressing time of the hot press equipment is preset to 10 to 30 seconds to ensure that the adhesive melts fully and bonds with the material surface, while avoiding potential damage to the components due to excessive heat.

[0063] Once the equipment reaches the preset temperature, the component to be fixed is placed between the upper and lower heating plates of the hot press. At this point, the hot press begins to heat up, and the pre-applied adhesive on the first and second insulating layers gradually softens and melts. Simultaneously, the hot press gradually applies pressure. Uniform pressure ensures a tight bond between the busbar, flexible circuit board, and insulating layer, preventing the formation of air bubbles or voids. Maintaining the set temperature and pressure for a period allows the adhesive to fully impregnate the material surface, forming a strong bond. After the hot pressing process, the temperature is slowly reduced, allowing the adhesive to gradually cool and solidify under pressure, helping to avoid internal stress or material deformation caused by sudden cooling. Once the temperature has dropped to a certain level, the pressure is released, and the bonded component is removed. At this point, the busbar, flexible circuit board, first insulating layer, and second insulating layer in the component are firmly bonded together, forming an integrated structure with good electrical insulation and mechanical stability.

[0064] In some embodiments, after step S3, i.e., after placing the component to be fixed into the SMT process line, performing component mounting, hot pressing, and soldering to fix the component to be fixed to obtain the bus assembly, the method further includes:

[0065] Clean the busbar assembly;

[0066] The busbar components are subjected to quality inspection after cleaning.

[0067] Specifically, after hot pressing is completed, the appearance of the bus assembly is inspected to ensure that there are no bubbles, delamination or misalignment; then a peel test is performed to verify the bonding strength and check whether the bonding force between the bus, flexible circuit board and insulating layer meets the requirements; then a continuity test is performed to ensure that the electrical connection of the solder joints between the bus and the flexible circuit board is normal, and an insulation test is performed to confirm the isolation performance of the insulating film.

[0068] Referring to Figures 2 to 7, embodiments of this application also provide a battery module, including multiple individual battery cells 1 and a busbar assembly 2. The multiple individual battery cells 1 are arranged along the length and width directions of the busbar assembly 2. Specifically, the multiple individual battery cells 1 are arranged sequentially along the length direction of the busbar assembly 2 to form a column of individual battery cells 1, and multiple columns of individual battery cells 1 are arranged sequentially along the width direction of the busbar assembly 2. Furthermore, because the individual battery cells 1 are cylindrical, adjacent individual battery cells 1 are staggered along the width direction to compensate for the gaps caused by the cylindrical shape of the battery, thereby making the arrangement of the multiple individual battery cells 1 more compact, saving internal space of the battery module, and improving battery integration.

[0069] Multiple individual battery cells 1 are connected to busbar assembly 2. Busbar assembly 2 is used to electrically connect multiple individual battery cells 1 and to monitor the operating condition of individual battery cells 1 in real time. Compared with each individual battery cell 1 being electrically connected by a connector, the circuit is simpler.

[0070] It should be noted that the busbar assembly 2 is prepared by the busbar assembly preparation method described in any of the foregoing embodiments.

[0071] In some embodiments, as shown in Figures 3 to 7, the bus assembly 2 includes:

[0072] The first insulating layer 21 and the second insulating layer 22 are arranged opposite to each other;

[0073] Busbar 23 is disposed between the first insulating layer 21 and the second insulating layer 22;

[0074] Flexible circuit board 24 is disposed between bus 23 and first insulating layer 21;

[0075] The flexible circuit board 24 has a closed outer edge and covers the busbar 23. The flexible circuit board 24 has multiple cutouts to expose the positive and negative portions of the busbar 23.

[0076] In detail, the bus assembly 2 includes a first insulating layer 21 and a second insulating layer 22 disposed opposite to each other, and a bus 23 located between the two. The bus 23 is the core component for connecting multiple individual cells 1 in the battery module, through which electrical energy is collected and distributed. The first insulating layer 21 and the second insulating layer 22 are made of materials with high insulation performance to ensure electrical isolation and prevent electrical short circuits in the battery module during operation. The two insulating layers are disposed opposite to each other, covering the upper and lower surfaces of the bus 23 to form an integral bus 23 structure. The bus 23 is located between the two insulating layers and is responsible for connecting the positive and negative terminals of each individual cell 1, constituting the electrical connection of the battery module. The bus 23 can be made of copper, aluminum, or other metals with excellent conductivity, and its surface can be tin-plated or otherwise treated for corrosion protection as needed to improve its durability and conductivity. In this embodiment, the busbar 23 is made of nickel, which facilitates the soldering between the busbar 23 and the flexible circuit board 24. Specifically, nickel can be directly soldered to the flexible circuit board 24 with tin, resulting in a stronger solder bond under the condition of meeting the overcurrent requirement. A flexible circuit board 24 is disposed between the first insulating layer 21 of the busbar 23 and the busbar 23. This flexible circuit board 24 is a plate structure that covers one surface of the busbar 23. Unlike the multiple flexible sub-boards in the prior art, the flexible circuit board 24 in this invention covers the busbar 23 in one go, greatly reducing the complexity of installation and the number of alignment operations. To achieve the electrical connection of the positive and negative terminals of the battery, the flexible circuit board 24 has multiple cutouts. These cutouts are used to expose the positive and negative terminals of the busbar 23, thereby achieving the electrical connection between the battery and the busbar 23, making the electrical connection of the battery module simpler, and avoiding installation errors caused by multiple alignment operations.

[0077] In this embodiment, the number and shape of the cutouts are matched to the structure of the busbar 23 to ensure precise exposure and good contact of the positive and negative electrodes. Specifically, the cutouts can be rectangular, circular, or other suitable shapes, and are evenly arranged along the length of the flexible circuit board 24 to achieve simultaneous multi-point connection.

[0078] The technical solution provided in this application sets the flexible circuit board 24 as a plate and opens multiple hollow parts on the flexible circuit board 24 to expose the positive and negative electrode parts of the busbar 23. This allows the flexible circuit board 24 to be integrally formed into a plate shape without interfering with the exposure of the positive and negative electrodes of the busbar 23. As a result, when the busbar 23, the flexible circuit board 24, the first insulating layer 21 and the second insulating layer 22 are stacked and assembled, the assembly and fixation of the multi-layer components can be achieved by only one alignment and one unified welding. This is beneficial to improving the efficiency of the assembly of the busbar assembly 2, and thus improving the production efficiency of the battery module.

[0079] In some embodiments, as shown in Figure 5, the flexible circuit board 24 includes a circuit board body 241 and a connector 244. The circuit board body 241 is equipped with a temperature sensor and a voltage sensor, and is electrically connected to the connector 244 to achieve real-time acquisition and transmission of key parameter information of the battery module, such as voltage and temperature. The circuit board body 241 covers the area between the positive and negative portions of the busbar 23, and exposes the positive and negative electrodes of the busbar 23 through multiple cutouts, facilitating subsequent electrical connections of the busbar 23. The circuit board body 241 is made of a flexible and conductive material, such as polyimide or other suitable flexible substrates, ensuring its flexible arrangement within the complex space of the battery module.

[0080] To monitor the operating status of the battery module, a temperature sensor (not shown in the figure) and a voltage sensor (not shown in the figure) are integrated on the circuit board 241. These sensors are located at different positions on the circuit board 241 to collect temperature and voltage signals from the battery module. In practical applications, the temperature sensor can be placed near the current channel of the battery module to accurately monitor the heat generated by the busbar 23 and the individual battery cells 1 during operation. The voltage sensor is placed at key nodes of the battery module to detect voltage changes of each individual battery cell 1 in real time.

[0081] Connector 244 is located at one end of circuit board 241 and is electrically connected to the temperature sensor and voltage sensor on circuit board 241. Through connector 244, the acquired voltage and temperature signals can be transmitted to an external control system or battery management system (BMS). Connector 244 can adopt a standard multi-pin design to ensure a stable electrical connection and support high-speed data transmission. The choice of material for connector 244 is also crucial; its housing should possess high durability and anti-interference performance to ensure that the transmission of sensor data is unaffected by electromagnetic interference or environmental factors.

[0082] During installation, the integrated design of the circuit board 241 simplifies the installation steps of the flexible circuit board 24 and avoids electrical connection instability caused by inaccurate alignment of multiple sub-boards. Simultaneously, the integrated temperature and voltage sensor design enables the battery module to monitor key parameters in real time during operation, effectively improving the safety and reliability of the battery system.

[0083] Furthermore, the flexible circuit board 24 also includes a support plate 242, which is located at one end of the circuit board body 241, and the connector 244 is located on the support plate 242. The support plate 242 is made of a rigid material, such as fiberglass reinforcement or metal sheet, which differs from the substrate of the circuit board body 241, effectively preventing bending deformation in this area. The support plate 242 is positioned at the connection end of the circuit board body 241, i.e., the location where the flexible circuit board 24 is electrically connected to external devices. Through this design, the support plate 242 can effectively improve the mechanical stability of the connection end of the flexible circuit board 24, avoiding damage to the flexible circuit board 24 due to frequent insertion and removal or other external forces. By arranging the connector 244 on the support plate 242, not only is the stable installation of the connector 244 ensured, but also other parts of the flexible circuit board 24 are prevented from being damaged by frequent connection operations. In addition, the presence of the support plate 242 allows the connector 244 to be firmly fixed to the flexible circuit board 24, ensuring a stable electrical connection during long-term use.

[0084] In some embodiments, multiple cutout portions are arranged along the length of the flexible circuit board 24 to form a cutout portion group 2411, and the multiple cutout portion groups 2411 are spaced apart along the width of the flexible circuit board 24. The busbar 23 includes multiple busbar groups, which are spaced apart along the width direction, and at least a portion of one busbar group is aligned with one cutout portion group 2411. By aligning at least a portion of one busbar group with one cutout portion group 2411, it can be ensured that the positive and negative terminals of each individual battery 1 in the battery module can be accurately connected to the corresponding portion of the busbar 23. Specifically, the cutout portion groups 2411 are arranged at the same intervals as the busbar groups, and are all aligned and installed in groups, which helps to reduce adjustment time during installation and improves the stability of the electrical connection.

[0085] In some embodiments, the cutout assembly 2411 includes a plurality of first through holes 24111 and a plurality of second through holes 24112. The plurality of first through holes 24111 are arranged in a continuous manner along the length direction, and the plurality of second through holes 24112 are arranged at intervals along the length direction. The first through holes 24111 are a group of connecting holes arranged along the length direction of the flexible circuit board 24. The first through holes 24111 are arranged in a continuous and continuous manner, that is, each first through hole 24111 is connected to each other to form a channel along the length direction. Through this continuous arrangement, the first through holes 24111 can expose a portion of the busbar assembly over a longer area, ensuring that the contact area for electrical connections is sufficiently large. Relative to the first through holes 24111, the second through holes 24112 are arranged at intervals along the length direction of the flexible circuit board 24. The positions of the second through holes 24112 are adjacent to the first through holes 24111, but they are not arranged in a continuous manner; instead, they are distributed on the flexible circuit board 24 in an intermittent manner. The second through hole 24112 is usually circular, rectangular or other irregular shape, without limitation, as long as it can expose the corresponding part in the busbar assembly.

[0086] Furthermore, the spaced arrangement of the first through-hole 24111 and the second through-hole 24112 also serves a heat dissipation function. The presence of these through-holes allows a portion of the busbar 23 to be directly exposed, thus helping to dissipate heat generated by the battery module during operation, reducing the operating temperature of the busbar 23, and facilitating the flexible circuit board 24's detection of the temperature within the battery module.

[0087] Furthermore, the multiple first through holes 24111 and the multiple second through holes 24112 are staggered along the width direction to accommodate the staggered arrangement of multiple individual cells 1 in the width direction, ensuring that each individual cell 1 can be connected to the corresponding busbar group through the first through hole 24111 and the second through hole 24112.

[0088] Furthermore, multiple solder joints 243 are formed on the flexible circuit board 24, and each solder joint 243 is located between two adjacent first through holes 24111 along the length direction. Placing the solder joints 243 between two adjacent first through holes 24111 makes full use of the space in the length direction of the flexible circuit board 24, and the formation of the solder joints 243 between two adjacent first through holes 24111 also helps to improve the uniformity and stability of the welding fixation.

[0089] In some embodiments, as shown in FIG. 6, the busbar assembly includes a plurality of busbars 231. The plurality of busbars 231 are arranged at intervals along the length direction, and each busbar 231 is aligned with at least two adjacent first through holes 24111 and two adjacent second through holes 24112, with the two first through holes 24111 and the two second through holes 24112 offset in the width direction. It should be noted that the four offset first through holes 24111 and second through holes 24112 specifically refer to two first through holes 24111 and two second through holes 24112 that are adjacent along the length direction, and these two first through holes 24111 and the corresponding two second through holes 24112 are offset in the width direction. This offset arrangement ensures reliable electrical contact between the busbars 231 and the positive and negative terminals, and improves the connection stability of the entire busbar assembly 2. In more detail, when each busbar 231 is arranged along its length, its connection portion spans two first through holes 24111 and two second through holes 24112 in the length direction, and spans adjacent first through holes 24111 and second through holes 24112 in the width direction. This staggered arrangement in the width direction allows the busbars 231 and through holes to utilize the space of the flexible circuit board 24 more efficiently, avoids interference between through holes, and ensures the independence of electrical connections.

[0090] In some embodiments, the busbar 231 includes a first sub-piece 2311, a second sub-piece 2312, and an inclined segment 2313. The first sub-piece 2311 and the second sub-piece 2312 are connected by the inclined segment 2313, and the first sub-piece 2311 and the second sub-piece 2312 are offset along the width direction. A portion of the first sub-piece 2311 is aligned with a first through-hole 24111, and a portion is aligned with an adjacent first through-hole 24111. Even though the first sub-piece 2311 can be exposed in the length direction through two adjacent first through-holes 24111, the electrical properties of these two portions are opposite. Similarly, a portion of the second sub-piece 2312 is aligned with a second through-hole 24112, and a portion is aligned with an adjacent second through-hole 24112. Even though the second sub-piece 2312 can be exposed in the length direction through two adjacent second through-holes 24112, the electrical properties of these two portions are opposite. The first sub-piece 2311 and the second sub-piece 2312 have the same structure and size, which facilitates the centralized production of the busbar 231. Furthermore, the first sub-piece 2311 and the second sub-piece 2312 are connected by an inclined section 2313, which ensures that the first sub-piece 2311 and the second sub-piece 2312 are staggered in the width direction, and also reduces the number of times the busbar 231 needs to be aligned.

[0091] Furthermore, the first sub-plate 2311 includes a positive electrode connection portion 23111, a negative electrode connection portion 23112, and a welding bump 23113. The positive electrode connection portion 23111 and the negative electrode connection portion 23112 are integrally formed along the length direction. The welding bump 23113 is provided on the positive electrode connection portion 23111 and protrudes towards the second insulating layer 22. The welding bump 23113 protrudes towards the second insulating layer 22 to facilitate welding of the first sub-plate 2311. The positive electrode connection portion 23111 of the first sub-plate 2311 is aligned and connected with a first through hole 24111, so that the first through hole 24111 can expose the positive electrode connection portion 23111. The negative electrode connection portion 23112 is aligned and connected with another first through hole 24111 adjacent in the length direction, so that the other first through hole 24111 can expose the negative electrode connection portion 23112. Similarly, since the second sub-plate 2312 and the first sub-plate 2311 have the same structural dimensions, the second sub-plate 2312 also has a corresponding positive electrode connection part 23111, negative electrode connection part 23112 and welding bump 23113, which will not be described in detail here.

[0092] Furthermore, the positive electrode connection portion 23111 has a positive electrode positioning notch 23114, and the negative electrode connection portion 23112 has a negative electrode positioning notch 23115. The positive electrode positioning notch 23114 and the negative electrode positioning notch 23115 are aligned in the length direction. When the busbar 23 is stacked onto the single cell 1, the positive electrode positioning notch 23114 and the negative electrode positioning notch 23115 of the positive electrode connection portion 23111 and the negative electrode connection portion 23112 respectively cooperate with the preset positioning plate, so that the busbar 23 can be accurately and quickly stacked onto the single cell 1, and then the positioning plate can be removed.

[0093] In some embodiments, the busbar 23 further includes a positive busbar 232, a negative busbar 233, a positive plate 234, a negative plate 235, and a plurality of intermediate busbars 236. The positive plate 234 and the negative plate 235 are arranged obliquely opposite each other. Specifically, the busbar 23 is rectangular, and the positive plate 234 and the negative plate 235 are located near the diagonal. The positive electrode plate 234 is connected to the positive electrode busbar 232, and the negative electrode plate 235 is connected to the negative electrode busbar 233. The end of the positive electrode busbar 232 away from the positive electrode plate 234 is connected to the positive electrode connection portion 23111 of the first sub-plate 2311 and the positive electrode connection portion 23111 of the second sub-plate 2312 of a busbar 231. The end of the negative electrode busbar 233 away from the negative electrode plate 235 is connected to the negative electrode connection portion 23112 of the first sub-plate 2311 and the negative electrode connection portion 23112 of the second sub-plate 2312 of a busbar 231. Multiple individual cells 1 can be integrated and connected through one positive electrode busbar 232, one negative electrode busbar 233, multiple busbar groups, and multiple intermediate busbars 236. The number of individual cells 1 is much greater than the number of intermediate busbars 236 and also greater than the number of busbars 231. In each busbar 231, the first sub-branch 2311 is connected to a single cell 1, and the second sub-branch 2312 is connected to a single cell 1, thus enabling one busbar 231 to be connected to two single cells 1 simultaneously.

[0094] In addition, the intermediate busbars 236 are arranged along the width and length directions, and all intermediate busbars 236 are located on the current path conducted by the positive busbar 232 and the negative busbar 233, forming a serpentine current path. Specifically, at least one intermediate busbar 236 is provided along the width direction. In this embodiment, two intermediate busbars 236 are provided along the width direction, and at least two intermediate busbars 236 are provided along the length direction. The two intermediate busbars 236 are staggered along the length direction to correspond to the oblique arrangement of the positive plate 234 and the negative plate 235. The current path at this time is that the current flows from the positive electrode plate 234 along the length direction through the first intermediate busbar 236, and then flows through the intermediate busbar 236 along the length direction towards the other intermediate busbar 236 opposite it, and then flows towards the other intermediate busbar 236, so that the current flow path is a serpentine shape that meanders back and forth. Correspondingly, the structure composed of the positive electrode busbar 232, multiple intermediate busbars 236 and negative electrode busbar 233 is serpentine, thereby improving the integration of multiple single cells 1.

[0095] It should also be noted that the intermediate busbar 236 has four connection ends, meaning that one intermediate busbar 236 can connect two groups of adjacent busbars in the width direction, which helps to save costs.

[0096] In summary, the technical solution provided in this application mainly involves setting the flexible circuit board 24 as a single plate and creating multiple cutouts on the flexible circuit board 24 to expose the positive and negative portions of the busbar 23. This allows the flexible circuit board 24 to be integrally formed into a single plate shape without interfering with the exposure of the positive and negative electrodes of the busbar 23. Consequently, when the busbar 23, flexible circuit board 24, first insulating layer 21, and second insulating layer 22 are stacked and assembled, only one alignment and one unified welding are required to assemble and fix the multi-layer components. This improves the efficiency of assembling the busbar assembly 2 and, consequently, the production efficiency of the battery module.

Claims

1. A method for manufacturing a busbar assembly, the method comprising: The first insulating layer, busbar, flexible circuit board and second insulating layer are stacked sequentially. The first insulating layer, the busbar, the flexible circuit board, and the second insulating layer, which are stacked together, are laminated and pre-fixed to form the component to be fixed. The component to be fixed is placed in the SMT process line, and the component to be fixed is subjected to component mounting, hot pressing and soldering to obtain the bus assembly.

2. The method of making a busbar assembly as defined in claim 1, wherein, Before the step of sequentially stacking the first insulating layer, busbar, flexible circuit board, and second insulating layer, the method further includes: On the side of the busbar facing the flexible circuit board.

3. The method of producing a busbar assembly according to claim 1 or 2, wherein, Before the step of sequentially stacking the first insulating layer, busbar, flexible circuit board, and second insulating layer, the method further includes: Solder paste is applied to the side of the flexible circuit board facing the bus.

4. The method of making a busbar assembly of claim 3, wherein, Before the step of sequentially stacking the first insulating layer, busbar, flexible circuit board, and second insulating layer, the method further includes: Adhesive is applied to the side of the first insulating layer facing the busbar.

5. The method of claim 4, wherein the busbar assembly is prepared by the steps of: Before the step of sequentially stacking the first insulating layer, busbar, flexible circuit board, and second insulating layer, the method further includes: Adhesive is applied to the side of the second insulating layer facing the flexible circuit board.

6. The method of making a busbar assembly as claimed in any one of claims 1 to 5, wherein, The first insulating layer, the second insulating layer, the busbar, and the flexible circuit board are all integrally formed by stamping.

7. The method of manufacturing busbar assemblies as claimed in any one of claims 1 to 6, wherein, The step of placing the component to be fixed into an SMT process line, performing component mounting, hot pressing, and soldering to fix the component to obtain a bus assembly includes: The component to be fixed is placed into the SMT process line, and the flexible circuit board in the component to be fixed is mounted with components. Reflow soldering is performed on the assembly to be fixed with the aforementioned components mounted on it. The busbar assembly is obtained by hot-pressing the components to be fixed after reflow soldering.

8. The method of making a busbar assembly of claim 7, wherein, The step of reflow soldering the assembly to be fixed with the mounted components includes: The assembly to be fixed, on which the aforementioned components are mounted, is placed in a reflow oven; The temperature in the reflow oven is adjusted to melt the solder paste used for soldering, thereby completing the soldering of the components to the flexible circuit board and the soldering of the flexible circuit board to the busbar.

9. The method of claim 8, wherein the busbar assembly is prepared by the steps of: The reflow oven is pre-programmed with a temperature profile, which includes a preheating section, a reflow section, and a cooling section.

10. The method of claim 9, wherein the busbar assembly is prepared by the steps of: The temperature range of the preheating section is 100℃-180℃, the temperature range of the reflux section is 230℃-250℃, and the temperature range of the cooling section is 0℃-100℃.

11. A bus assembly, said bus assembly being manufactured by the method of manufacturing a bus assembly as described in any one of claims 1 to 10, said bus assembly comprising: The first and second insulating layers are arranged opposite to each other; A busbar is disposed between the first insulating layer and the second insulating layer; A flexible circuit board is disposed between the busbar and the first insulating layer; The flexible circuit board has a closed outer edge and covers the busbar. The flexible circuit board has multiple cutouts that expose the positive and negative portions of the busbar.

12. The busbar assembly of claim 11, wherein, The flexible circuit board includes a circuit board body and a connector. The circuit board body is electrically connected to the connector. A temperature sensor and a voltage sensor are provided on the circuit board body.

13. The busbar assembly of claim 12, wherein, The flexible circuit board also includes a support plate, which is disposed at one end of the circuit board body, and the connector is located on the support plate.

14. The busbar assembly of any one of claims 11 to 13, wherein, Multiple cutout portions are arranged along the length direction of the flexible circuit board to form a cutout portion group, and multiple cutout portion groups are arranged at intervals along the width direction of the flexible circuit board; The busbar includes multiple busbar groups, which are spaced apart along the width direction, and at least a portion of one busbar group is aligned with one of the cutout groups.

15. The bus assembly of claim 14, wherein, The hollowed-out part group includes a plurality of first through holes and a plurality of second through holes. The plurality of first through holes are arranged along the length direction and are connected along the length direction. The plurality of second through holes are arranged at intervals along the length direction.

16. The bus assembly of claim 15, wherein, The plurality of first through holes and the plurality of second through holes are staggered along the width direction.

17. The busbar assembly of claim 16, wherein, The flexible circuit board has multiple solder joints formed thereon, and along the length direction, each solder joint is located between two adjacent first through holes.

18. The bus assembly of claim 16, wherein, The busbar assembly includes multiple busbars, which are spaced apart along the length direction. Each busbar is aligned with at least two adjacent first through holes and two adjacent second through holes, and the two first through holes and the two second through holes are offset in the width direction.

19. The bus assembly of claim 18, wherein, The busbar includes a first sub-section, a second sub-section, and an inclined section. The first sub-section and the second sub-section are connected through the inclined section, and the first sub-section and the second sub-section are offset along the width direction.

20. A battery module comprising a plurality of individual cells and a bus assembly as described in any one of claims 11 to 19, wherein the plurality of individual cells are arranged along the length direction and the width direction, and adjacent individual cells are staggered along the width direction, and all of the plurality of individual cells are connected to the bus.

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