Patent Publication Number: US-2021184379-A1

Title: FPCB Assembly for Battery Module, Its Manufacturing Method, and Battery Module Including the Same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/KR2019/013752 filed Oct. 18, 2019, published in Korean, which claims priority from Korean Patent Application No. 10-2018-0159520 filed Dec. 11, 2018, all of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates to a flexible printed circuit board (FPCB) used for sensing a voltage of a battery module, and more particularly, to a FPCB assembly for a battery module, which is configured by connecting several FPCBs provided in a simple form, and its manufacturing method and a battery module including the FPCB assembly. 
     BACKGROUND ART 
     Generally, a printed circuit board (PCB) is widely used for various electronic products such as TVs, computers, mobile phones, displays, communication networks, and secondary battery modules. As a kind of the PCB, in particular, a flexible printed circuit board (FPCB) having insulation and flexibility is widely used recently. 
     Specifically, the FPCB is prepared by laminating a dry film on a copper foil laminate in which a copper foil is formed on a polyimide film to form a conductor pattern through exposure, development and etching processes, and then bonding a coverlay film to an outermost copper foil. The FPCB is installed in a bent state inside a complex product case or used for a repeatedly moving part by utilizing the flexibility of its raw material. Due to the nature of the FPCB, the FPCB is used in various ways for miniaturization (digital cameras, camcorders, or the like), flexibility (print heads, hard disks, or the like), high density wiring (precision devices such as medical instruments), and rationalization of assembly (measuring instruments, vehicle electronics, battery modules, or the like). 
     A conventional battery module uses a lot of harness wire as a means for sensing a voltage of the battery cell and transmitting a signal. However, it has been repeatedly found that the harness wire causes a problem in the space inside the battery module and the contact with a connector, so the FPCB is being frequently used as an alternative thereto. 
     Meanwhile, the FPCB for sensing a voltage of a battery module is mainly used in a battery module configured using a pouch-type secondary battery in which a positive electrode lead and a negative electrode lead are located at opposite sides, so its shape is designed in approximately an I-type, or in an E-type or an F-type in consideration of the addition of a temperature sensor or the like. 
     However, if the FPCB is prepared in the I-type, the E-type or the F-type shape as above, too much scraps may remain. For example, the FPCB may be prepared by cutting or stamping a predesigned FPCB shape from a FPCB sheet having a polyamide film and a copper foil. However, as shown in  FIG. 1 , in an E-type FPCB  1 , an unused space  3  remains too much in a FPCB sheet  2  due to its geometric shape. The unused space  3 , namely the scrap, is mostly not reused and discarded. This is a major reason for the increase in the material cost of FPCB. Thus, there is a need for a method or a FPCB design to minimize an unused space in the FPCB sheet  2 . 
     SUMMARY 
     Technical Problem 
     The present disclosure is designed to solve the problems of the related art, and therefore the present disclosure is directed to saving a material cost compared to the conventional technique by designing a FPCB to utilize the space of a FPCB sheet to the maximum. 
     However, the technical problem to be solved by the present disclosure is not limited to the above, and another objects not mentioned above will be clearly understood by those skilled in the art from the following description of the invention described. 
     Technical Solution 
     In one aspect of the present disclosure, there is provided a flexible printed circuit board (FPCB) assembly for a battery module, which includes an insulated flexible film, and conductor patterns arranged inside the film in a predetermined form and configured to transmit an electric signal, a main FPCB portion configured to extend longitudinally in a first direction; and a sub FPCB portion assembled to at least one side of the main FPCB portion and configured to extend longitudinally in a second direction different from the first direction. 
     The main FPCB portion may include first connector terminals positioned at at least one side thereof, and the sub FPCB portion may include second connector terminals positioned at a region of the sub FPCB portion that is configured to be assembled to the main FPCB, wherein the second connector terminals are configured to be fitted into the first connector terminals. 
     Each of the first connector terminals may be shaped as a socket-type female connector pin, and each of the second connector terminals may be shaped as a male connector pin that is inserted into the female connector pin. 
     The first connector terminals and the second connector terminals may be configured to be compressed when connected to each other. 
     A first film portion in a region of the main FPCB portion including the first connector terminals may be concave, and a second film portion in a region of the sub FPCB portion including the second connector terminals may be convex. 
     The main FPCB portion may include a single part , the sub FPCB portion may include multiple parts, and each part of the sub FPCB portion may be configured to be assembled with the main FPCB portion. 
     The sub FPCB portion may include a first sub FPCB part and a second sub FPCB part, and the first sub FPCB part and the second sub FPCB part may be respectively assembled to opposing longitudinal ends of the main FPCB portion and disposed to extend longitudinally in the second direction, wherein the second direction is not parallel to the first direction. 
     At least one voltage sensing terminal may be attached to each of the first sub FPCB part and the second sub FPCB part, and at least one temperature sensor may be attached to the main FPCB portion. 
     In another aspect of the present disclosure, there is also provided a method of manufacturing the FPCB assembly for a battery module including an insulated flexible film and conductor patterns arranged inside the film in a predetermined form and configured to transmit an electric signal. The method may include: separating a main FPCB portion of the FPCB assembly on a first FPCB sheet including a plurality of main FPCB portions from a sub FPCB portion of the FPCB assembly on a second FPCB sheet including a plurality of the sub FPCB portions; and assembling the main FPCB portion to the sub FPCB portion by connecting first connector terminals positioned at at least one side of the main FPCB portion to second connector terminals positioned at at least one side of the sub FPCB portion. 
     Each of the first connector terminals may be shaped as a socket-type female connector pin, and shaped as a male connector pin, and assembling the main FPCB portion to the sub FPCB portion may include inserting the second connector terminals into the first connector terminals. 
     Assembling the main FPCB portion to the sub FPCB portion may include compressing the first connector terminals and the second connector terminals by a clinching process after being connected to each other. 
     In still another aspect of the present disclosure, there is also provided a battery module, comprising the FPCB assembly for a battery module as described in any of the embodiments herein. 
     Advantageous Effects 
     According to an embodiment of the present disclosure, a FPCB assembly for a battery module having a complicated shape may be configured by connecting a plurality of FPCBs having a simple shape to each other. The FPCBs having a simple shape may be arranged in the FPCB sheet so that an unused space remains less than the conventional technique. Thus, it is possible to minimize the amount of scrap discarded after manufacturing the FPCB, thereby reducing the material cost. 
     According to another embodiment of the present disclosure, a FPCB assembly for a battery module having an I shape, a T shape, an E shape, an F shape, or the like may be implemented in a simpler and more economical way than the conventional technique by adopting connector pins to be fitted into unit FPCBs having approximately a straight shape. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram for illustrating space utilization of a FPCB sheet when a conventional FPCB for a battery module is manufactured, as a reference. 
         FIGS. 2 and 3  are an exploded perspective view and an assembled perspective view showing a FPCB assembly according to an embodiment of the present disclosure. 
         FIG. 4  a diagram for illustrating an example where the FPCB assembly for a battery module as shown in  FIG. 3  is installed. 
         FIG. 5  is a diagram showing a modified example of the FPCB assembly according to an embodiment of the present disclosure. 
         FIGS. 6 and 7  are diagrams for illustrating a connection structure of a main FPCB and a sub FPCB according to an embodiment of the present disclosure. 
         FIG. 8  is a diagram for illustrating a compressing method of connector pins of  FIG. 7 , as a reference. 
         FIGS. 9 and 10  are diagrams for illustrating space utilization of a FPCB sheet when the FPCB for a battery module according to an embodiment of the present disclosure is manufactured, as a reference. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Prior to the description, it should be understood that the terms used in the specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation. 
     Therefore, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the disclosure, so it should be understood that other equivalents and modifications could be made thereto without departing from the scope of the disclosure. 
     A FPCB assembly described below may be included in a battery module and used as a wiring component that senses a voltage and a temperature of secondary battery cells and transmits the same to a battery management system (BMS). Here, the use of the FPCB assembly according to the present disclosure is not limited as a voltage sensing component of the battery module. For example, the FPCB assembly may also be used to transmit a signal or power provided by one device or circuit board to another device or circuit board. 
       FIGS. 2 and 3  are an exploded perspective view and an assembled perspective view showing a FPCB assembly according to an embodiment of the present disclosure. 
     Referring to these figures, a FPCB assembly  10  for a battery module according to an embodiment of the present disclosure includes a main FPCB  20  and two sub FPCBs  30   a  and  30   b  provided to be assembled to the main FPCB  20 . 
     The main FPCB  20  and the two sub FPCBs  30   a ,  30   b  include conductor patterns  11  for transmitting electric signals and a film for protecting the conductor patterns  11  and giving insulation and flexibility thereto, and are assembled as shown in the figures to form a single FPCB assembly  10 . 
     The main FPCB  20  extends in one direction, and the two sub FPCBs  30   a ,  30   b  take extend in a direction different from the main FPCB  20 . Referring to  FIGS. 2 and 3 , the main FPCB  20  is arranged to extend along a Y-axis direction and the two sub FPCBs  30   a ,  30   b  are connected to both ends of the main FPCB  20  and extend along an X-axis direction, respectively. 
     That is, the two sub FPCBs  30   a ,  30   b  include a first sub FPCB  30   a  and a second sub FPCB  30   b , and the first sub FPCB  30   a  and the second sub FPCB  30   b  are respectively assembled to one longitudinal end and the other longitudinal end of the main FPCB  20  to extend in a direction that intersects the main FPCB  20 . 
     The first sub FPCB  30   a  and the second sub FPCB  30   b  include a voltage sensing terminal  35 , which is a part for sensing the voltage of the battery cells and extend in a direction different from the main FPCB  20  serving as a main wiring, and this is to improve accessibility to electrode leads of the battery cells. 
     As shown in  FIG. 4 , the FPCB assembly  10  for a battery module may be mounted to a cell stack  100 . Here, the cell stack  100  may be referred to as an aggregate of pouch-type battery cells in which the pouch-type battery cells are provided to stand erectly and stacked in one direction. 
     The main FPCB  20  is disposed at an upper surface of the cell stack  100  along a longitudinal direction thereof, and the first sub FPCB  30   a  and the second sub FPCB  30   b  are respectively disposed at a front surface and a rear surface of the cell stack  100  at which the electrode leads  101  are located. The electrode leads  101  of the battery cells may be welded to bus bars on integrated circuit boards (ICBs)  110 ,  120 , and the voltage sensing terminals  35  of the first sub FPCB  30   a  and the second sub FPCB  30   b  are attached to the bus bars to sense the voltage of the battery cells. 
     A temperature sensor  25  is attached to the main FPCB  20  so that the temperature sensor  25  senses the temperature of the battery cells. Battery cells in operation may have a temperature difference depending on their areas, so the number and location of the temperature sensor  25  attached thereto may be differently selected as necessary. 
     This embodiment discloses an I-shaped or H-shaped FPCB assembly  10  in which two sub FPCBs  30   a ,  30   b  are assembled to a single main FPCB  20 . However, unlike this embodiment, one sub FPCB or three or more sub FPCBs  30   a ,  30   b  may also be assembled to the main FPCB  20  to form the FPCB assembly  10  in more various shapes. 
     That is, the FPCB assembly  10  may be assembled such that at least one sub FPCB  30   a ,  30   b  is stretched in various directions from the single main FPCB  20 . 
     For example,  FIG. 5  shows a modified example of this embodiment. In the FPCB assembly  10  shown in  FIG. 5 , two sub FPCBs  30   c ,  30   d  are further assembled to a center region of the main FPCB  20 . That is, the FPCB assembly  10  according to this modified example is configured by assembling one main FPCB  20  and four sub FPCBs  30   a ,  30   b ,  30   c ,  30   d . The FPCB assembly  10  allows the temperature sensors  25  to be easily disposed at both edge regions of the cell stack  100  along the width direction. 
     Subsequently, the connection structure of the main FPCB  20  and the sub FPCBs  30   a ,  30   b  will be described with reference to  FIGS. 6 to 8 . 
     In this embodiment, the connection structure of the main FPCB  20  and the sub FPCB  30   a ,  30   b  may be implemented using a connector connection method. For this purpose, as shown in  FIG. 6 , the main FPCB  20  has first connector terminals  21  provided to at least one side thereof, and the sub FPCBs  30   a ,  30   b  have second connector terminals  31  provided to a region assembled to the main FPCB  20 .  31  and fitted into the first connector terminal  21 . 
     Each of the first connector terminals  21  may be provided to have a shape of a socket-type female connector pin, and each of the second connector terminals  31  may be provided to have a shape of a male connector pin that may be inserted into the female connector pin. 
     The female connector pins and the male connector pins are connected to the conductor patterns  11  of the FPCB assembly  10  in one-to-one relationship, respectively. For example, the female connector pins and the male connector pins may be made of a conductive metal such as copper or nickel and attached to the corresponding conductor patterns  11  by shouldering or the like, respectively. In this embodiment, eight conductor patterns  11  are provided, but the number of the conductor patterns  11  may increase or decrease depending on the number of signals to be transmitted by the conductor patterns  11 . 
     As shown in  FIG. 7 , the sub FPCBs  30   a ,  30   b  are connected to main FPCB  20  as the second connector terminals  31  are inserted into the first connector terminals  21  of the main FPCB  20 . Of course, at this time, the conductor patterns  11  of the main FPCB  20  and the sub FPCBs  30   a ,  30   b  are also electrically connected. 
     In this embodiment, the first connector terminal  21  and the second connector terminal  31  may be further compressed in a clinching process to further secure the contact reliability of the first connector terminals  21  and the second connector terminals  31 . 
     For example, as shown in  FIG. 8 , after the second connector terminal  31  is fitted into the first connector terminal  21 , the fitted portion may be placed between compression jigs  40   a ,  40   b  and pressed by the compression jigs  40   a ,  40   b  such that the first connector terminal  21  and the second connector terminal  31  are compressed integrally. The main FPCB  20  and the sub FPCBs  30   a ,  30   b  connected in this way are not easily disconnected even though a tensile strength is applied thereto. 
     In addition, a film in a region of the main FPCB  20  of this embodiment to which the first connector terminals  21  are provided is formed concave, and a film in a region of the sub FPCBs  30   a ,  30   b  to which the second connector terminals  31  are provided is formed convex. If the region to which the first connector terminals  21  of the main FPCB  20  is defined as a concave portion  23  and the region to which the second connector terminals  31  of the sub FPCB  30   a ,  30   b  are provided is defined as a convex portion  33 , the concave portion  23  and the convex portion  33  may be provided to be engaged with each other. 
     In this case, if the convex portions  33  of the sub FPCBs  30   a ,  30   b  are aligned with the concave portions  23  of the main FPCB  20  and then pushed therein, the eight first connector terminals  21  and the second connector terminals  31  may be naturally fitted with each other without being distorted from each other. Thus, the main FPCB  20  and the sub FPCBs  30   a ,  30   b  may be easily assembled without damaging the connector terminals. 
     Next, a method of manufacturing the above FPCB assembly  10  will be briefly described. 
     The method of manufacturing the FPCB assembly  10  includes a FPCB component preparing step and a FPCB assembling step. 
     As shown in  FIGS. 8 and 9 , the main FPCBs  20  are designed in the same pattern in a first FPCB sheet  50 , and the sub-FPCBs  30   a ,  30   b  are designed in the same pattern in a second FPCB sheet  60  similarly. In this case, the main FPCBs  20  and the sub FPCBs  30   a ,  30   b  may be designed approximately in a straight line form so that the areas of the first FPCB sheet  50  and the second FPCB sheet  60  are used to the maximum, thereby minimizing the amount of scrap discarded. 
     The main FPCBs  20  and the sub FPCBs  30   a ,  30   b  are cut off from the first FPCB sheet  50  and the second FPCB sheet  60  according to their shapes, respectively, to prepare FPCB components, and then the FPCB assembling step is performed. 
     The FPCB assembling step is very simple. First, the second connector terminals  31  provided to one side of the sub FPCBs  30   a ,  30   b  are inserted into the first connector terminals  21  provided to both ends of the main FPCB  20  to form the shape of the FPCB assembly  10 . Here, as described above, the first connector terminals  21  may be provided to have a form of a socket-type female connector pin, and the second connector terminals  31  may be provided to have a shape of a rod-type male connector pin that may be inserted into the female connector pin. 
     After that, the first connector terminals  21  and the second connector terminals  31  are integrally compressed using a clinching process. As shown in  FIG. 8 , the clinching process may be performed in a way that the compression jigs press a region where the first connector terminals  21  and the second connector terminals  31  are connected. According to the clinching process, the main FPCB  20  and the sub FPCBs  30   a ,  30   b  are firmly fixed to each other so that the main FPCB  20  and the sub FPCBs  30   a ,  30   b  are not easily disconnected even though a tensile force is applied thereto to some extent. 
     According to the method of manufacturing the FPCB assembly  10  as described above, it is possible to reduce the amount of scrap discarded after manufacturing the FPCB assembly, thereby reducing the material cost. Also, the FPCB assembly for a battery module having an I shape, a T shape, an E shape, an F shape or the like may be simply manufactured by selectively combining several FPCBs having a simple shape. 
     Meanwhile, a battery module according to the present disclosure may be configured to include the FPCB assembly  10  described above. The FPCB assembly  10  may be used to sense the voltage of battery cells included in the battery module. In addition to the FPCB assembly  10 , the battery module may further include a cell stack  100  formed by stacking a plurality of pouch-type battery cells, ICBs  110 ,  120  for electrically connecting the battery cells, a module case (not shown) for accommodating the battery cells, and other control devices such as a fuse, a relay and a BMS for controlling the charge/discharge and current flow of the battery cells based on the voltage and temperature of the battery cells. 
     The present disclosure has been described in detail. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the scope of the disclosure will become apparent to those skilled in the art from this detailed description. 
     Meanwhile, even though the terms expressing directions such as “upper”, “lower”, “left” and “right” are used in the specification, they are just for convenience of description and can be expressed differently depending on the location of a viewer or a subject, as apparent to those skilled in the art.