HYBRID CIRCUIT BOARD AND BATTERY PACK HAVING SAME

Embodiments of the present disclosure relate to a hybrid circuit board and a battery pack having the same. The battery pack includes: a plurality of battery cells arranged in one direction, each of the battery cells including a positive electrode terminal and a negative electrode terminal; a plurality of busbars electrically connected to the positive electrode terminal or the negative electrode terminal of each of the battery cells; and a hybrid circuit board including a rigid substrate and a flexible substrate that is coupled to the rigid substrate and is electrically connected to the busbars. The rigid substrate is arranged between the busbars and the flexible substrate.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2021-0035284, filed on Mar. 18, 2021, in the Korean Intellectual Property Office, the content of which is herein incorporated by reference in its entity.

BACKGROUND

Aspects of embodiments of the present disclosure relate to a hybrid circuit board and a battery pack having the same.

2. Description of the Related Art

Generally, a battery pack includes a plurality of battery cells, a busbar electrically connecting the battery cells to the outside (e.g., to an outside load), and a rigid circuit board that is electrically connected to the busbar and on which various circuits and components are mounted.

The busbar is mounted on the rigid circuit board by using bolts and insert nuts, which may cause the height of the battery pack to be increased. In addition, to absorb swelling of a battery cell, a separate terminal having a swelling-absorption structure should be bolted between the rigid circuit board and the battery cell. Further, a tox clinching process should be used for connecting the busbar, and thus, there are problems in that the structure of the battery pack and battery module becomes complicated, the costs increase, and it may be difficult to reduce the height of the module.

SUMMARY

The present disclosure provides a hybrid circuit board having a rigidity-reinforcement and swelling-absorption structure and a battery pack having the same.

The present disclosure also provides a hybrid circuit board having a simple busbar connection structure that avoids increasing the height of a module, and a battery pack having the same.

A hybrid circuit board according to an embodiment of the present disclosure includes: a flexible substrate including (or made of) a flexible material that is configured to be electrically connected to a plurality of busbars, which electrically connect a plurality of battery cells; and a rigid substrate including (or made of) a rigid material that is coupled to the flexible substrate to support the flexible substrate.

The flexible substrate may include a plurality of tab connection portions along an edge thereof, and a substrate tab may be electrically connected to each of the tab connection portions and the busbars.

The flexible substrate may have a first shape portion at both sides of the tab connection portion, and the first shape may be concavely cut inwardly from a corresponding edge of the flexible substrate.

The flexible substrate may have a second shape portion extending from a corresponding edge of the flexible substrate in an ‘S’ shape and integrally formed with the tab connection portion.

One end of the substrate tab may be soldered to the tab connection portion, and the other end thereof may be laser-welded to the busbar.

The flexible circuit board may further include a sensor connection portion extending in an ‘S’ shape from one of the edges of the flexible substrate. The sensor connection portion may include a temperature sensor configured to measure the temperature of at least one of the battery cells, a foam pad accommodating the temperature sensor, and a metal tab coupled to the foam pad and connected to the temperature sensor and the at least one battery cell.

A battery pack, according to an embodiment of the present disclosure, includes: a plurality of battery cells arranged in one direction, each of the battery cells including a positive electrode terminal and a negative electrode terminal; a plurality of busbars electrically connected to the positive electrode terminal or the negative electrode terminal of each of the battery cells; and a hybrid circuit board including a rigid substrate and a flexible substrate that is coupled to the rigid substrate and is electrically connected to the busbars. The rigid substrate is arranged between the busbars and the flexible substrate.

The flexible substrate may include a plurality of tab connection portions along edges thereof, and a substrate tab may be electrically connected to each of the tab connection portions and the busbar.

The flexible substrate may have a first shape portion formed at both sides of the tab connection portion, and the first shape may be concavely cut inwardly from a corresponding edge of the flexible substrate.

The flexible substrate may have a second shape portion extending from one of the edges of the flexible substrate in an ‘S’ shape and integrally formed with the tab connection portion.

One end of the substrate tab may be soldered to the tab connection portion, and the other end thereof may be laser-welded to the busbar.

The flexible substrate may include a sensor connection portion extending in an ‘S’ shape from one of the edges of the flexible substrate. The sensor connection portion may include a temperature sensor configured to measure the temperature of at least one of the battery cells, a foam pad accommodating the temperature sensor, and a metal tab coupled to the foam pad and connected to the temperature sensor and the battery cell.

DETAILED DESCRIPTION

Embodiments of the present disclosure are provided to more completely explain the present disclosure, and the following embodiments may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete and will convey the aspects and features of the present disclosure to a person skilled in the art.

In addition, in the accompanying drawings, sizes or thicknesses of various components may be exaggerated for brevity and clarity. Like numbers refer to like elements throughout. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. In addition, it will be understood that when an element A is referred to as being “connected to” an element B, the element A can be directly connected to the element B or an intervening element C may be present therebetween such that the element A and the element B are indirectly connected to each other.

The terminology used herein is for the purpose of describing particular embodiments and is not intended to be limiting of the disclosure. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms that the terms “have,” “comprise,” or “include” and variations thereof, such as “having,” “comprising,” or “including,” when used in this specification, specify the presence of stated features, numbers, steps, operations, elements, and/or components but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, components, and/or groups thereof.

Spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the element or feature in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “on” or “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below, etc. Further, the use of “may” when describing embodiments of the present disclosure relates to “one or more embodiments of the present disclosure.” Expressions, such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. As used herein, the terms “use,” “using,” and “used” may be considered synonymous with the terms “utilize,” “utilizing,” and “utilized,” respectively. As used herein, the terms “substantially,” “about,” and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent variations in measured or calculated values that would be recognized by those of ordinary skill in the art.

Hereinafter, a hybrid circuit board and a battery pack having the same according to embodiments of the present disclosure will be described, in detail, with reference to the accompanying drawings.

FIG. 1is a partially exploded perspective view of a battery pack according to an embodiment of the present disclosure,FIG. 2is an exploded perspective view of the hybrid circuit board shown inFIG. 1,FIG. 3is a plan view of the hybrid circuit board shown inFIG. 2,FIG. 4is an enlarged plan view of the portion “A” ofFIG. 3, andFIG. 5is an enlarged plan view of the portion “B” ofFIG. 3.

As shown inFIG. 1, a battery pack1according to an embodiment of the present disclosure includes a plurality of battery cells10, a cell frame20which aligns and supports the battery cells10, a plurality of busbars40, which are electrically connected to the battery cells10, and a busbar holder30, which supports the busbars40. The battery pack1may further include a hybrid circuit board50on which various circuits and components are mounted. The busbars40may be electrically connected to the hybrid circuit board50, and the hybrid circuit board50may be electrically connected to the outside of the battery pack1through a separate connector. The battery pack1may be referred to as a battery module.

The battery cells10may have a rectangular parallelepiped shape, and a plurality of battery cells10may be arranged in a line along a direction (e.g., a predetermined direction). Here, each of the battery cells10may be arranged so that their relatively wide plate surfaces face each other. The cell frame20is provided to align the battery cells10. Each of the battery cells10may include a rectangular parallelepiped-shaped case, an electrode assembly accommodated together with an electrolyte in the case, and a cell cap12for sealing the case.

The electrode assembly may be formed by sequentially winding or stacking a negative electrode plate, a separator, and a positive electrode plate. A negative electrode active material, such as graphite or carbon, may be applied or coated on the negative electrode plate. The negative electrode plate may be formed of a metal foil, such as copper, copper alloy, nickel, or nickel alloy. An active material, such as a transition metal oxide, may be applied or coated on the positive electrode plate. The positive electrode plate may be formed of a metal foil, such as aluminum or an aluminum alloy. An uncoated region, that is, an area to which an active material is not applied, may be formed on the negative electrode plate and the positive electrode plate, respectively. A negative electrode tab may be connected to the negative electrode uncoated region, and a positive electrode tab may be connected to the positive electrode uncoated region. The negative electrode tab and the positive electrode tab, connected in this way, may be respectively electrically connected to the negative electrode terminal and the positive electrode terminal formed in the cell cap12. The negative and positive electrode terminals on the cell cap12are electrically connected to the busbars40.

The cell frame20includes a pair of end plates22that are in contact with the battery cells10at both ends along the arrangement direction of the battery cells10, a pair of side plates24coupled orthogonally to the end plates22, and a top plate26coupled to an upper portion of the hybrid circuit board50. On the basis ofFIG. 1, a bottom plate of the cell frame20is provided on the lower portion of the battery cells10to support the battery cells10from the lower portion. On the basis ofFIG. 1, the end plates22support the battery cells10in the front-rear direction, the side plates24support the battery cells10in the left-right direction, and the top plate26support the battery cells10in the upper direction, respectively. The end plate22, the side plates24, the top plate26, and the bottom plate (not shown) are coupled to one another to form a substantially rectangular parallelepiped frame, and the battery cells10, the busbar holder30and the busbars40, and the hybrid circuit board50, are accommodated therein.

The busbar holder30may be seated on top of the cell cap12on the basis ofFIG. 1. The busbar holder30is a substantially rectangular plate, and a plurality of openings (e.g., through holes), through which the positive and negative electrode terminals of the cell cap12are exposed, may be formed therein. The busbar holder30may be made of an insulating material. When the positive electrode terminal and the negative electrode terminal are exposed through the openings formed in the busbar holder30, the busbar40are electrically connected to the exposed positive electrode terminal and the negative electrode terminal.

The busbar40may electrically connect the positive electrode terminal and the negative electrode terminal (e.g., the positive electrode terminal of one of the battery cells10to the negative electrode terminal of another one of the battery cells10). The busbar40may connect the plurality of battery cells10in series and/or in parallel. To this end, a plurality of busbars40may be provided. In one example, the busbars40may electrically connect non-adjacent battery cells10from among the battery cells10arranged in a row. In other embodiments, the busbars40may electrically connect the positive electrode terminal of one battery cell10and a positive electrode terminal or a negative electrode terminal of another battery cell10. In addition, the busbar40may electrically connect the negative electrode terminal of one battery cell10and a positive electrode terminal or a negative electrode terminal of another battery cell10. The busbar40may be connected to the positive electrode terminal and the negative electrode terminal by welding or the like. Areas other than the busbar40and the positive and negative electrode terminals may be insulated by the busbar holder30. The hybrid circuit board50is disposed between the busbar(s)40and the top plate26.

As shown inFIG. 2, the hybrid circuit board50may include a rigid substrate50aand a flexible substrate50b.

The rigid substrate50ais coupled to the flexible substrate50bto support the flexible substrate50band to reinforce (or improve) rigidity. The rigid substrate50amay be simply formed of a reinforcing material for reinforcement without circuit mounting. In other embodiments, the rigid substrate50amay be a printed circuit board (PCB) on which a circuit is mounted. Because the rigid substrate50asupports the flexible substrate50b,it may have a shape similar to that of the flexible substrate50b.The rigid substrate50amay have the same size as the flexible substrate50bor a slightly smaller size. The rigid substrate50amay have a substantially rectangular shape and may be disposed so that a long side direction coincides with an arrangement direction of the battery cells10. On the basis ofFIG. 1, the flexible substrate50bis coupled to the upper portion of the rigid substrate50a.

The flexible substrate50bis a substrate made of a flexible material having lower strength than the rigid substrate50a.The flexible substrate50bmay be (or may be referred to as) a flexible printed circuit assembly (FPCA) or a flexible printed circuit board (FPCB). In the flexible substrate50b,various parts (or components or circuits) for measuring state information of the battery cells10, such as voltages and/or temperatures of the battery cells10, and various parts (or components or circuits) for controlling and/or managing the battery cells10, may be mounted.

As shown inFIGS. 2 and 3, the flexible substrate50bmay have a substantially rectangular shape, and a first tab connection portion510and a second tab connection portion520may be formed at edges thereof in the long side (or length) direction. A substrate tab530is connected to the first tab connection portion510and the second tab connection portion520, respectively. The flexible substrate50bmay be disposed such that the long side direction coincides with an arrangement direction of the battery cells10. Because the flexible substrate50bis to be connected to the busbars40, the flexible substrate50bshould cover a certain portion (or size) or more of the area of the busbar holder30. The flexible substrate50bmay have a different size than the busbar holder30but may have a size sufficient to be at least adjacent to the installation area for the busbars40for a smooth connection with the busbars40. For example, the flexible substrate50bmay have a short side (or width) length corresponding to an interval between the left busbars40and the right busbars40shown inFIG. 1. In addition, the flexible substrate50bmay have a long side length equal to the sum of the widths of the left or right busbars40in the arrangement direction of the battery cells10.

As shown inFIGS. 2 and 3, a plurality of first and second tab connection portions510and520may be formed on the edges of the flexible substrate50bin the longitudinal (or long side or length) direction. However, the first tab connection portion510and the second tab connection portion520may also be formed on the edges of the flexible substrate50bin the short side (or width) direction.

As shown inFIGS. 2 to 4, the first tab connection portion510is a portion of the flexible substrate50bto which the substrate tab530, which is electrically connected to the busbar40, is connected. The first tab connection portion510may be formed to have a size the same as or slightly larger than the size of a portion to which the substrate tab530is welded (hereinafter, referred to as a first welding portion). A first shape portion512that is cut in an approximately water-droplet shape may be formed in the flexible substrate50bat both sides of the first tab connection portion510.

The first shape portion512is concavely cut inwardly from an edge of the flexible substrate50bin the long side direction and is provided on both sides of the first tab connection portion510. Because the first tab connection portion510is a free end due to the first shape portion512and is a flexible material, the first tab connection portion510can move with a degree of freedom in the vertical, horizontal, and horizontal directions, on the basis ofFIG. 1. The first tab connection portion510is connected to the busbar40by the substrate tab530, and the busbar40is connected to the cell cap12. Therefore, even if vibration is transmitted to the first tab connection portion510when swelling occurs in the battery cell10, the swelling can be absorbed by the first shape portion512. Accordingly, damage to the first tab connection portion510or damage to connection portions of the substrate tab530and the busbar40can be mitigated or prevented. The first shape portion512for absorbing swelling may be implemented in a different shape depending on a distance from the busbar40or interference with the busbar holder30.

As shown inFIGS. 2, 3, and 5, the second tab connection portion520, to which the substrate tab530is connected, may be formed on the flexible substrate50b,and a second shape portion522having an approximately ‘S’ shape may be provided. For example, the second shape portion522includes an extension portion522aextending in a straight line from one end of the edge of the flexible substrate50b,a curved portion522bintegrally formed with the extension portion522aand having an approximately ‘S’ curve shape, and a connection portion522cformed integrally with the curved portion522band formed in a straight line to be connected to the second tab connection portion520. The second tab connection portion520, to which the substrate tab530is connected, is formed at an end of the connection portion522cof the second shape portion522. In addition, the second shape portion522has a width smaller than the size of the second tab connection portion520and is spaced apart from the end of the flexible substrate50b.Therefore, because the second tab connection portion520becomes a free end due to the second shape portion522and is a flexible material, the second tab connection portion520can move with a degree of freedom in the vertical, horizontal, left, and right directions, on the basis ofFIG. 1. Accordingly, swelling of the battery cells10may also be absorbed by the second shape portion522.

As such, the first tab connection portion510should be able to flow with a degree of freedom (e.g., a predetermined degree of freedom). Accordingly, when the rigid substrate50ais coupled to the flexible substrate50b,the extended length of the portion of the rigid substrate50asupporting the first tab connection portion510(hereinafter, referred to as a support portion50a′) may be smaller than the extended length of the first tab connection portion510. As used herein, the extended length is a distance at which the first tab connection portion510protrudes from the end of the flexible substrate50b.In other embodiments, the support portion50a′ of the rigid substrate50amay not be fixed to the first tab connection portion510. For example, the extended length of the support portion50a′ may be the same as the extended length of the first tab connection portion510.

In addition, similar to the first tab connection portion510, the second tab connection portion520should be able to flow with a degree of freedom (e.g., a predetermined degree of freedom). To this end, the rigid substrate50amay be shaped so as not to support a portion of the flexible substrate50bwhere the second tab connection portion520is formed. For example, the rigid substrate50amay be shaped such that the portion where the second tab connection portion520is formed is empty.FIG. 2shows an embodiment in which the portion of the rigid substrate50acorresponding to the second tab connection portion520of the flexible substrate50bis empty.

As shown inFIGS. 4 and 5, the substrate tab530is a metal tab for connecting the first tab connection portion510and the second tab connection portion520to the busbars40, respectively. For example, the substrate tab530may be made of a nickel material. The substrate tab530may include a plurality of substrate tabs, and they may have a substantially rectangular shape. One end of the substrate tab530is coupled to the first tab connection portion510or the second tab connection portion520, and the other end thereof extends to the outside of the first tab connection portion510or the second tab connection portion520. Part or all of a region of the substrate tab530, except for one end thereof, may be coupled to the busbars40. One end of the substrate tab530that is coupled to the first tab connection portion510or the second tab connection portion520may be defined as a first welding portion532, and the remaining portion may be defined as a second welding portion534. For example, the first welding portion532may be connected to the first tab connection portion510or the second tab connection portion520by soldering, and the second welding portion534may be connected to the busbar40by laser welding. However, both the first welding portion532and the second welding portion534may be welded by ultrasonic welding or laser welding. For example, when the first welding portion532and the second welding portion534are physically coupled (e.g., are integrally formed) and electrically connected to the first tab connection portion510, the second tab connection portion520, or the busbars40, the coupling method is not limited. In addition, the first welding portion532and the second welding portion534may have different shapes than those shown in the drawings, which are provided by way of example. In other words, the shapes if the first welding portion532and the second welding portion534are not limited thereto.

As described above, because the flexible substrate50band the busbar40are electrically connected by the substrate tab530, a bolting process and bolting parts for connecting the substrate and the busbar holder30may be omitted. In addition, tox clinching, which is a type of riveting process for bonding dissimilar metals, for connecting a substrate and the busbars40may be omitted. Therefore, the assembly quality is improved, the quality can be stabilized, and the cost can be reduced by the omission of parts.

FIG. 6Ais a cross-sectional view schematically illustrating a state in which a conventional busbar holder and a rigid circuit board are coupled.FIG. 6Bis a cross-sectional view schematically illustrating a coupling state between a busbar holder and a hybrid circuit board of a battery pack according to an embodiment of the present disclosure.

As shown inFIG. 6A, conventionally, a busbar holder (b) is disposed on a cell cap (a), a rigid circuit board (e) is placed on the busbar holder (b), and the rigid circuit board (e) is then fixed to the busbar holder (b) by using an insert nut (c) and a bolt (d). Thereafter, a top plate (f) is fastened on the rigid circuit board (e). For example, a height ranging from the top plate (f) to the head of the bolt (d) may be about 2.4 mm, and a height ranging from the head of the bolt (d) to the bottom of the busbar holder (b) may be about 13 mm (hereinafter, the sum of the two heights is defined as a module height). That is, in the conventional structure, the module height is about 15.4 mm.

In contrast, when the hybrid circuit board50according to embodiments of the present disclosure is applied, the coupling structure is, according to an embodiment, as shown inFIG. 6B. As shown inFIG. 6B, a busbar holder30is placed on a cell cap12, and a hybrid circuit board50on which components are mounted is placed on the busbar holder30. Thereafter, a top plate26is disposed on the hybrid circuit board50. For example, a height ranging from the top plate26to the top end of a component mounted on the hybrid circuit board50may be about 2.4 mm, and a height ranging from the top end of the component mounted on the hybrid circuit board50to the bottom of the busbar holder30may be about 8 mm. Therefore, the module height according an embodiment of the present disclosure is about 10.4 mm, and thus, the module height can be greatly reduced compared to the conventional structure shown inFIG. 6A.

Hereinafter, a structure of a hybrid circuit board according to another embodiment of the present disclosure will be described, and a detailed description of the same configuration as that of the previous embodiment will be omitted.

FIG. 7is a plan view of a hybrid circuit board according to another embodiment of the present disclosure,FIG. 8is an enlarged perspective view of the portion “C” ofFIG. 7, andFIG. 9is an enlarged bottom perspective view of portions of the portion “C” shown inFIG. 8.

As shown inFIG. 7, in the hybrid circuit board50′ according to another embodiment of the present disclosure, a plurality of first tab connection portions510and a sensor connection portion540may be formed on a flexible substrate50b′. Here, the first tab connection portion510may have the same shape and structure as that shown inFIG. 4. As shown inFIG. 7, however, the substrate tab530may be formed in a rectangular shape without a separate welding portion. A similar configuration of the substrate tab530may also be applied to the embodiment shown inFIG. 4.

The sensor connection portion540may extend from one edge of the flexible substrate50b′ in an approximately ‘S’ shape. A foam pad542on which a temperature sensor544is mounted may be coupled to the extended (or distal) end of the sensor connection portion540. The foam pad542has a hexahedron shape having a thickness (e.g., a predetermined thickness), and an accommodation space in which the temperature sensor544is mounted may be formed on (or in) the foam pad542. For example, the foam pad542may be formed to surround (e.g., to surround in a plan view or to extend around a periphery of) the temperature sensor544. A metal tab546(see, e.g.,FIG. 9) electrically connected to the temperature sensor544and connected to the battery cell10or the cell cap12may be coupled to the lower portion of the foam pad542in the direction facing the busbar40. For example, the metal tab546may be made of an aluminum material. The temperature of the battery cell10may be measured by attaching the metal tab546to the surface of the battery cell10by using a double-sided tape or the like. Accordingly, the shape and length of the sensor connection portion540may vary depending on a position to which the metal tab546is attached. By including the sensor connection portion540, the processes and parts for connecting a temperature sensor to a board with a separate connector and wire, and welding the temperature sensor to a battery cell and installing the same, may be omitted. Accordingly, the cost can be reduced and the process can be simplified due to omission of parts. The above-described sensor connection portion540may also be applied to the hybrid circuit board50shown inFIG. 3.

In the hybrid circuit board according to embodiments of the present disclosure having the above-described structure, components are not mounted on the edge of a flexible board having a swelling absorption structure formed thereon. The component is mounted on a portion that is less affected by swelling and is supported by a rigid substrate. For example, components may be disposed at a central portion spaced apart from the edge along the longitudinal direction of the flexible substrate.

According to embodiments of the present disclosure, by having both the characteristics of a rigid circuit board and a flexible circuit board, the rigidity of the substrate can be reinforced.

In addition, the hybrid circuit board according to embodiments of the present disclosure has a swelling absorption structure and can be connected to the busbar without a bolting process, and thus, a separate swelling absorption structure may be omitted and the busbar connection structure can be simplified. Accordingly, a cause of increased height of a battery pack is eliminated, thereby enabling a battery pack having a reduced or minimum height.

While the foregoing embodiments are only some embodiments for carrying out the present disclosure, which is not limited to these embodiments, it will be understood by a person skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the following claims and their equivalents.