Abstract:
A battery pack including a cap plate; a bare cell, the bare cell being sealed by the cap plate; and a circuit board facing the cap plate, wherein the circuit board includes opening units adjacent to edges thereof, the opening units providing an opening for coupling the circuit board to the cap plate.

Description:
BACKGROUND 
       [0001]    1. Field 
         [0002]    Embodiments relate to a battery pack. 
         [0003]    2. Description of the Related Art 
         [0004]    Due to technical development and production growth for mobile devices, e.g., mobile phones and laptop computers, demand for secondary batteries as energy sources has rapidly increased. Currently, as fossil fuel is being replaced, studies on use of secondary batteries in, e.g., electric vehicles and hybrid vehicles, are actively being carried out. 
         [0005]    In general, secondary batteries may be used in the form of a battery pack including a circuit structure for controlling charging and discharging operations. 
       SUMMARY 
       [0006]    Embodiments are directed to a battery pack. 
         [0007]    At least one of the above and other features and advantages may be realized by providing a battery pack including a cap plate; a bare cell, the bare cell being sealed by the cap plate; and a circuit board facing the cap plate, wherein the circuit board includes opening units adjacent to edges thereof, the opening units providing an opening for coupling the circuit board to the cap plate. 
         [0008]    The opening units may have a closed hole structure surrounded by sidewalls of the circuit board. 
         [0009]    The opening units may have an open groove structure in which sides of the circuit board around the opening units are open toward an outside of the circuit board. 
         [0010]    The battery pack may further include combining members between the opening units and the cap plate. 
         [0011]    The combining members may include metal plates fixed to the circuit board. 
         [0012]    The combining members and the cap plate may be welded at welding regions corresponding to the opening units. 
         [0013]    The circuit board may include a pair of opening units, the pair of opening units being at opposite edges of the circuit board. 
         [0014]    The circuit board may include a terminal hole at a center thereof, the terminal hole exposing an electrode terminal of the cap plate. 
         [0015]    The battery pack may further include a PTC device, the PTC device having one end connected to the circuit board and another end connected to the electrode terminal exposed through the terminal hole. 
         [0016]    The battery pack may further include an external connection terminal on the circuit board, the external connection terminal including at least two separate terminals spaced apart from each other by gap spaces. 
         [0017]    The external connection terminal may have a first height from the circuit board, a PTC device on the circuit board may have a second height from the circuit board, and the first height may be greater than the second height. 
         [0018]    The circuit board may include a first surface facing the cap plate and a second surface opposite to the first surface, combining members on the first surface of the circuit board and corresponding to the opening units, the combining members coupling the circuit board to the cap plate, and a PTC device and an external connection terminal on the second surface of the circuit board. 
         [0019]    At least one of the above and other features and advantages may also be realized by providing a battery pack including a cap plate; a bare cell, the bare cell being sealed by the cap plate; a circuit board on the cap plate; and an external connection terminal on the circuit board, wherein the external connection terminal includes at least two separate terminals spaced apart from each other by gap spaces. 
         [0020]    The external connection terminal may include first and second power source terminals, the first and second power source terminals each having a first width; and a signal transmission terminal between the first and second power source terminals, the signal transmission terminal having a second width, wherein the second width is narrower than the first widths. 
         [0021]    The external connection terminal may include metal blocks on the circuit board. 
         [0022]    The external connection terminal may include patterned terminal patterns on the circuit board. 
         [0023]    The terminal patterns may be formed from a raw material paste. 
         [0024]    The circuit board may include opening units on edges thereof, the opening units providing an opening for coupling the circuit board to the cap plate. 
         [0025]    The battery pack may further include combining members on the circuit board between the opening units and the cap plate. 
         [0026]    The combining members and the cap plate may be coupled by welding through the opening units of the circuit board. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    The above and other features and advantages will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments with reference to the attached drawings, in which: 
           [0028]      FIG. 1  illustrates an exploded perspective view of a battery pack according to an embodiment; 
           [0029]      FIG. 2  illustrates an exploded perspective view of a part of the battery pack of  FIG. 1 ; 
           [0030]      FIG. 3  illustrates a cross-sectional view of the part of  FIG. 2  taken along a line III-III; 
           [0031]      FIG. 4  illustrates a cross-sectional view of a protective circuit module in an assembling state; 
           [0032]      FIG. 5  illustrates a plan view of the protective circuit module of  FIG. 4 ; 
           [0033]      FIGS. 6 and 7  illustrate perspective views of external connection terminals according to embodiments; 
           [0034]      FIG. 8  illustrates an exploded perspective view of an external connection terminal according to a comparative example; 
           [0035]      FIG. 9  illustrates an exploded perspective view of a battery pack according to another embodiment; 
           [0036]      FIG. 10  illustrates an exploded perspective view of a battery pack according to yet another embodiment; and 
           [0037]      FIG. 11  illustrates a plan view of a protective circuit module of  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION 
       [0038]    Korean Patent Application No. 10-2010-0072972, filed on Jul. 28, 2010, in the Korean Intellectual Property Office, and entitled: “Battery Pack,” is incorporated by reference herein in its entirety. 
         [0039]    Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. 
         [0040]    In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being “on” another element, it can be directly on the other element, or intervening elements may also be present. In addition, it will also be understood that when an element is referred to as being “between” two elements, it can be the only element between the two elements, or one or more intervening elements may also be present. Like reference numerals refer to like elements throughout. 
         [0041]    Hereinafter, embodiments will be described in more detail with reference to the accompanying drawings.  FIG. 1  illustrates an exploded perspective view of a battery pack according to an embodiment.  FIG. 2  illustrates an exploded perspective view of a part of the battery pack of  FIG. 1 .  FIG. 3  illustrates a cross-sectional view of the part of  FIG. 2  taken along a line  FIG. 4  illustrates a cross-sectional view of a protective circuit module in an assembling state.  FIG. 5  illustrates a plan view of the protective circuit module of  FIG. 4 . 
         [0042]    The battery pack may include a bare cell  100  having an electricity generation element and a protective circuit module (PCM)  145  on the bare cell  100 . The PCM  145  may control charging and discharging operations of the bare cell  100 . 
         [0043]    The bare cell  100  may include a rechargeable secondary battery, e.g., a lithium-ion cell. As illustrated in  FIG. 2 , the bare cell  100  may be formed by sealing an electrode assembly  10  including a positive electrode plate  11 , a negative electrode plate  13 , and a separator  15  in a can  20  with an electrolyte (not illustrated). For example, the bare cell  100  may include the electrode assembly  10  as a jelly roll structure formed by rolling a stack body including the positive electrode plate  11 , the negative electrode plate  13 , and the separator  15 , the can  20  having an open upper side for accommodating the electrode assembly  10  and the electrolyte, and a cap plate  30  for sealing the upper side of the can  20 . An airtight bond may be formed between the cap plate  30  and the can  20  using, e.g., laser welding. 
         [0044]    A positive electrode tab  17  and a negative electrode tab  19  may be respectively connected to the positive electrode plate  11  and the negative electrode plate  13 . For example, the positive electrode tab  17  may be directly connected to the cap plate  30 ; and the negative electrode tab  19  may be connected to an electrode terminal  31  protruding from the cap plate  30 . An insulation bond may be formed between the electrode terminal  31  and the cap plate  30 ; and the electrode terminal  31  may protrude from the cap plate  30 . 
         [0045]    The PCM  145  may control charging and discharging operations of the bare cell  100 . When an excessive current, e.g., above a predetermined threshold value, flows through the PCM  145 , when a temperature of the bare cell  100  increases above a set temperature, and/or when the bare cell  100  is excessively charged or discharged, the PCM  145  may block a current flow therethrough and may perform a protective operation for protecting the bare cell  100 . For example, the PCM  145  may include a circuit board  140 , a positive temperature coefficient PTC device  120 , and an external connection terminal  150 . The circuit board  140  may include a sensing circuit (not illustrated) for detecting state information, e.g., in regards to current, voltage, and the like, and/or a charging and discharging protective circuit (not illustrated). The PTC device  120  may be installed on the circuit board  140  and may control a charging or discharging current according to an increase of temperature. The external connection terminal  150  may be installed on the circuit board  140  and may relay an electric connection with an external device (not illustrated). In this regard, the PCM  145  may include passive devices, e.g., a charging and discharging switching device (field effect transistor (FET), a capacitor, and a resistor. 
         [0046]    The PTC device  120  may form a current path between the electrode terminal  31  of the cap plate  30  and the circuit board  140 . When a temperature of the bare cell  100  exceeds a set threshold value, an electric resistance of the PTC device  120  may increase. Accordingly, the PTC device  120  may reduce a charging or discharging current. For example, the PTC device  120  may include a variable resistor  125  and first and second lead members  121  and  122  such that an electric resistance of the variable resistor  125  may be changed according to temperature. The first and second lead members  121  and  122  may be formed on an upper side and a lower side of the variable resistor  125 , respectively, and may extend in different directions. For example, the first lead member  121  may be connected to the electrode terminal  31 , which may penetrate the circuit board  140  and may protrude from the circuit board  140 . The second lead member  122  may be connected to the circuit board  140 . 
         [0047]    A terminal hole  140 ′ exposing the electrode terminal  31  may be formed on, e.g., a center, of the circuit board  140 . For example, the electrode terminal  31  exposed through the terminal hole  140 ′ may be connected to the PTC device  120 . For example, the electrode terminal  31  may be connected to the first lead member  121  of the PTC device  120 . The electrode terminal  31  and the PTC device  120  may be bonded to each other by, e.g., welding. For example, a welding hole  121 ′ may be formed on the first lead member  121  of the PTC device  120 . In an implementation, the first lead member  121  and the electrode terminal  31  may be bonded to each other by welding the first lead member  121  and the electrode terminal  31  at the welding hole  121 ′. 
         [0048]    Opening units  130  of the circuit board  140  may be used when coupling, e.g., welding, the cap plate  30  to the circuit board  140 . The opening units  130  may be formed at, e.g., edges of the circuit board  140 , and may be formed as a pair symmetric with each other. In an implementation, the opening units  130  may be formed as holes surrounded by side walls of the circuit board  140 , e.g., closed holes penetrating and completely enclosed by the circuit board  140 . In another implementation, the opening units  130  may be formed as, e.g., open, holes in which sides of the circuit board  140  around the opening units  130  are open toward the outside of the circuit board  140 , e.g., may be formed as open grooves (see  FIG. 10 ). 
         [0049]    Combining members  135  may be interposed between the circuit board  140  and the cap plate  30 . For example, the combining members  135  may correspond to the opening units  130  of the circuit board  140 , may be fixed on lower sides of the circuit board  140 , and may contact the cap plate  30 . The combining members  135  may each include a metal plate and may each be formed of the same metal as the cap plate  30  in consideration of welding strength with the cap plate  30 . 
         [0050]    The combining members  135  may be coupled, e.g., welded, to the cap plate  30  through the opening units  130  of the circuit board  140 . As illustrated in  FIG. 3 , the opening units  130  of the circuit board  140  may provide paths for a welding tool R, e.g., a pole electrode for welding. The combining members  135  and portions of the cap plate  30  in contact therewith may be coupled to each other by, e.g., welding, through the opening unit  130 . In an implementation, the combining members  135  may be directly welded to the cap plate  30 . In another implementation, the combining members  135  may be welded to separate additional members  35  (see  FIG. 9 ) attached on the cap plate  30  for protecting the cap plate  30 . The combining members  135  may be directly welded to the cap plate  30  according to types of welding or types of welding heating source. Also, the combining members  135  may be welded to the cap plate  30  by using the separate additional members  35  for protecting the cap plate  30 . 
         [0051]    The external connection terminal  150  may relay an electrical connection with an external device. For example, the external connection terminal  150  may relay a current flow and a signal transmission/reception by forming an interface with an external load (e.g., a mobile device) or an external power supply device. For example, the external connection terminal  150  may include first and second power source terminals  151  and  152  each having a pattern with a relatively broad width and a signal transmission terminal  153  having a pattern with relatively narrow width. In an implementation, the widths of the first and second power source terminals  151  and  152  may each be wider than the width of the signal transmission terminal  153 . The first and second power source terminals  151  and  152  may include a positive electrode terminal and a negative electrode terminal, respectively, and may form an electric interface with an external device for inputting and outputting charging and discharging currents. 
         [0052]    In an implementation, the first and second power source terminals  151  and  152  may form a charging and discharging integrated terminal. However, the embodiments are not limited thereto, and a charging terminal and a discharging terminal may be separately formed or a charging and discharging terminal may be integrated or separated according to polarity. In this regard, the number and form of the external connection terminal  150  are not limited to the above. 
         [0053]    The signal transmission terminal  153  may be, e.g., interposed between the first power source terminal  151  and the second power source terminal  152 , and may form an electric interface for communicating data with an external device. The signal transmission terminal  153  may receive a control signal related to a charging or discharging operation from an external device or may transmit state information about, e.g., voltage, current, and/or temperature, measured in the battery pack to an external device. The signal transmission terminal  153  may form a data transmission path to an external device; and one or more signal transmission terminals  153  may be included, if desired. 
         [0054]    Referring to  FIG. 4 , the first and second power source terminals  151  and  152  may form a power transmission line and may have widths W 1  and W 2 , respectively, which may help prevent power loss according to resistances thereof. The signal transmission terminal  153  may form a signal transmission line and may have a width W 3 , which may help save or preserve mounting space on the circuit board  140 . 
         [0055]    The external connection terminal  150  may protrude from the circuit board  140  by a first height h 1 . For example, a top cover  160  may be coupled to the PCM  145 ; and the top cover  160  may receive the PCM  145  and couple to the bare cell  100 , thereby protecting the PCM  145 . In an implementation, the external connection terminal  150  protruding from the circuit board  140  by the first height h 1  may be exposed to the outside through an opening pattern  160 ′ of the top cover  160  and thus may maintain a stable connection with an external device. 
         [0056]    In an implementation, the first height h 1  of the external connection terminal  150  may be higher than a second height h 2  of the PTC device  120 . Accordingly, the external connection terminal  150  may be exposed to the outside from the top cover  160  and may be stably connected to an external device, whereas the PTC device  120  may be covered by the top cover  160  and protected by the top cover  160 . In an implementation, the second height h 2  may be, e.g., a height of the first lead member  121  of the PTC device  120  coupled to the electrode terminal  31 . For example, the height h 2  may be a height from a top surface of the circuit board  140  to a top surface of the first lead member  121 . 
         [0057]    The external connection terminal  150  may be formed by mounting a plurality of metal blocks in a terminal area of the circuit board  140 . In an implementation, the metal blocks may separately correspond to the first and second power source terminals  151  and  152  and the signal transmission terminal  153  for forming the external connection terminal  150 . Thus, the first and second power source terminals  151  and  152  and the signal transmission terminal  153  may be electrically insulated from each other. 
         [0058]    Referring to  FIG. 4 , the, e.g., thin, combining members  135  may be interposed between the circuit board  140  and the cap plate  30  and any spare space for containing elements other than the combining members  135  may not be required. Accordingly, a space for installing the PCM  145  may be small; and an upper space of the cap plate  30  over the PCM  145  may also be small so that the battery pack may be compact. For example, the combining members  135  may be formed on a first surface  140   a  of the circuit board  140  that faces the cap plate  30 ; and the PTC device  120  and the external connection terminal  150  may be formed on a second surface  140   b  that is opposite to the first surface  140   a.  Accordingly, the battery pack may be slim and compact. 
         [0059]    In a comparative example, a lead member bent in the form of steps may be interposed between the circuit board and the cap plate. One end and another end of the lead member may contact a lower surface of the circuit board and an upper surface of the cap plate, respectively. In this regard, a volume of the battery pack may increase due to space taken by the lead member. Also, a PTC device or an external connection terminal may be disposed in the space secured by the lead member, e.g., between the cap plate and circuit board. Thus, assembling strength may decrease according to a height of the lead member and an arrangement of other elements. For example, elements may not be tightly assembled and there may be spaces between the elements. However, according to an embodiment, a combined structure of the circuit board  140  and the cap plate  30  may be improved and overall volume of the battery pack may be reduced and elements of the battery pack may be tightly assembled through compact packing. Accordingly, assembling strength may be improved. 
         [0060]    An insulating label sheet (not illustrated) may be attached along an outer circumference of the bare cell  100 ; and an adhesive member  171  of  FIG. 1 , e.g., a double-sided tape, may be attached on a bottom of the bare cell  100  so that a lower cover  170  may be coupled to the bare cell  100 . 
         [0061]    As illustrated in  FIG. 5 , WR 1  represents a first welding area between the combining member  135  and the cap plate  30 ; and WR 2  represents a second welding area between the first lead member  121  of the PTC device  120  and the electrode terminal  31 . In an implementation, portions of the combining member  135  exposed through the opening units  130  may be heated by the welding tool R and may be welded to the cap plate  30 . 
         [0062]      FIGS. 6 and 7  illustrate perspective views of the external connection terminals  150  according to the embodiments. As illustrated in  FIG. 6 , a metal material having excellent electric conductivity may be processed in a block unit so as to form blocks  151 ′ and  152 ′ for the first and second power source terminals  151  and  152  and a block  153 ′ for the signal transmission terminal  153 . The metal blocks  151 ′, 152 ′, and  153 ′ may be respectively formed on contact pads  141 , 142 , and  143  spaced apart from each other on the circuit board  140  to insulate the first and second power source terminals  151  and  152  and the signal transmission terminal  153  from each other. For example, the metal blocks  151 ′, 152 ′, and  153 ′ may be coupled to the contact pads  141 , 142 , and  143  of the circuit board  140  by soldering, welding, or other conductive methods, e.g., using a conductive adhesive (not illustrated). The metal blocks  151 ′,  152 ′, and  153 ′ may have a rectangular or cuboid shape or may have other three dimensional shapes. 
         [0063]    As illustrated in  FIG. 7 , the external connection terminal  150  may include terminal patterns  151 ″,  152 ″ and  153 ″ on the circuit board  140 . For example, the terminal patterns  151 ″,  152 ″, and  153 ″ may be formed by coating a powder or paste raw material on a terminal area of the circuit board  140  through a pattern mask M. If desired, a hardening process may be performed after coating the raw material. 
         [0064]    Alternatively, a hardening process for the raw material entirely or continuously coated on the terminal area of the circuit board  140  may be selectively performed by using the pattern mask M so that a hardened part and a non-hardened part may be formed according to patterns defined by the pattern mask M. Then, the non-hardened part may be removed by, e.g., etching, thereby forming the terminal patterns  151 ″,  152 ″, and  153 ″. For example, the hardening process may include UV light hardening. 
         [0065]    The external connection terminal  150  formed as described above may include the first and second power source terminals  151  and  152  and the signal transmission terminal  153  spaced apart from each other by gap spaces g, as illustrated in  FIG. 4 . The first and second power source terminals  151  and  152  and the signal transmission terminal  153  may be insulated from each other by the gap spaces g therebetween. 
         [0066]      FIG. 8  illustrates an exploded perspective view of an external connection terminal  250  according to a comparative example. Referring to  FIG. 8 , the external connection terminal  250  may include a terminal housing  251  and terminal units  255  inserted in and fixed to the terminal housing  251 . The terminal housing  251  may form an external shape of the external connection terminal  250  and may include, e.g., an injection molding material formed of an insulating resin. The terminal housing  251  may include a plurality of assembling units  251   a  that define assembling positions of the terminal units  255 . The terminal units  255  may each be inserted in to the assembling units  251   a  to cover the assembling units  251   a  and may be insulated from each other by boundary walls  251   b.    
         [0067]    The terminal units  255  may include a plurality of conductive metal pieces bent according to external forms of the assembling units  251   a  and may surround outer surfaces of the assembling units  251   a.  The plurality of metal pieces corresponding to power source terminals and a signal transmission terminal may each be inserted into and fixed to the assembling units  251   a.  The terminal units  255  inserted into the terminal housing  251  may be welded to a wiring pattern of a circuit board. 
         [0068]    In the comparative example, heterogeneous materials, e.g., the insulating terminal housing  251  and the conductive terminal units  255 , may be used to form the external connection terminal  250 . The terminal units  255  may each be inserted into and fixed to the terminal housing  251  while being insulated from each other. However, according to the embodiments, the external connection terminal  150  may be formed by using a simple process for mounting the metal blocks in the terminal area of the circuit board  140 ; and the first and second power source terminals  151  and  152  and the signal transmission terminal  153  may be insulated from each other through the gap spaces g between the metal blocks. In this regard, the process of forming the external connection terminal  150  may be simple in the embodiments. 
         [0069]      FIG. 9  illustrates an exploded perspective view of a battery pack according to another embodiment. In the battery pack, the opening units  130  may be formed on edges, e.g., opposite edges, of the circuit board  140 ; and the circuit board  140  may be coupled to the cap plate  30  by, e.g., welding through the opening units  130 . In an implementation, the combining members  135  may be interposed between the circuit board  140  and the cap plate  30 . The combining members  135  may be fixed to the lower surface of the circuit board  140  and may correspond to the opening units  130  so as to face the cap plate  30 . 
         [0070]    For example, the opening units  130  may provide entering paths for a welding tool; and the combining members  135  and portions of the cap plate  30  in contact therewith may be coupled to each other by welding through the opening units  130 . As described above, the combining members  135  may be directly welded to the cap plate  30 . However, as illustrated in  FIG. 9 , the combining members  135  may be welded to separate additional members  35  coupled to the cap plate  30  for protecting the cap plate  30 . Thus, the combining members  135  may be welded to the cap plate  30  by using the separate additional members  35  for protecting the cap plate  30 . 
         [0071]      FIG. 10  illustrates an exploded perspective view of a battery pack according to yet another embodiment.  FIG. 11  illustrates a plan view of a protective circuit module of  FIG. 10 . 
         [0072]    In the battery pack, opening units  330  may be formed on edges of a circuit board  340 . For example, the opening units  330  may be formed on opposite edges of the circuit board  340  and may be formed as holes or grooves in which sides of the circuit board  340  adjacent to the opening units  330  are open toward the outside of the circuit board  340 . For example, the opening units  330  may have the form of holes or grooves in which at least one side thereof is open, instead of holes entirely enclosed by side walls of the circuit board (see  FIG. 1 ). 
         [0073]    Combining members  335  may be fixed to a lower surface of the circuit board  340  corresponding to the opening units  330  and may face the cap plate  30 . For example, the combining members  335  may be aligned with both ends of the circuit board  340 . 
         [0074]    For example, the opening units  330  may provide entering paths for a welding tool R; and the combining members  335  and portions of the cap plate  30  in contact therewith may be coupled to each other by welding through the opening units  330 . As illustrated in  FIG. 11  WR 1  represents a first welding area between the combining members  335  and the cap plate  30 ; and WR 2  represents a second welding area between the first lead member  121  of the PTC device  120  and the electrode terminal  31 . In an implementation, portions of the combining member  335  exposed through the opening units  330  may be heated by the welding tool R and may be welded to the cap plate  30 . 
         [0075]    In consideration of stability of secondary batteries including combustible materials, a circuit structure for efficiently controlling abnormalities, e.g., excessive charge, excessive discharge, excessive current, and the like may be included in the secondary battery. 
         [0076]    As described above, according to the embodiments, a coupling structure between a cap plate that seals a bare cell and a circuit board on the cap plate may be improved so that a battery pack may be compact and may have improved assembling strength. 
         [0077]    In addition, according to the embodiments, a structure of an external connection terminal that relays power supply and data communication with an external device may be improved so that a process of forming a battery pack may be simplified. 
         [0078]    Exemplary embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. Accordingly, it will be understood by those of ordinary skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.