Patent Publication Number: US-11043326-B2

Title: Power transformer and circuit board module

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefit of China application Ser. No. 201810586240.2, filed on Jun. 8, 2018. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a power transformer and a circuit board module, and particularly relates to a power transformer and a circuit board module capable of offering an efficient heat dissipation effect. 
     Description of Related Art 
     Currently, a rectifier transistor in a power supply dissipates heat by fixing an additional heatsink, for example, the additional heatsink is fixed by locking or attaching to the rectifier transistor and thereby increasing the heat dissipation area to cool off by making use of the heatsink. Specifically, for a vertical (e.g., in the To-220 package) rectifier transistor, such rectifier transistor is normally fixed to a heatsink and soldered to the circuit board together with the heatsink. As for a surface-mounted (e.g., in the SO8 package, which is soldered to a small-sized circuit board) rectifier transistor, such rectifier transistor is also connected to an additional heatsink for heat dissipation. In other words, all of the conventional rectifier transistors dissipate heat by resorting to additional heatsinks. However, such configuration makes it necessary to preserve an additional space for the heatsink to be fixed in the power supply, and the overall size of the power supply is difficult to be reduced. 
     SUMMARY OF THE INVENTION 
     One or some exemplary embodiments of the invention provide a power transformer capable of offering an efficient heat dissipation effect. 
     One or some exemplary embodiments provide a circuit board module. A power transformer of the circuit board module is capable of offering an efficient heat dissipation effect to a rectifier transistor. 
     A power transformer according to an embodiment of the invention includes at least one primary side conductive piece, at least one secondary side conductive piece, a first conductive strip pin, a second conductive strip pin, and an iron core set. The at least one secondary side conductive piece is stacked to the at least one primary side conductive piece along an axis. The first conductive strip pin extends from the at least one secondary side conductive piece, and the first conductive strip pin is bent and extends along the axis. The second conductive strip pin extends from the at least one secondary side conductive piece, and second conductive strip pin is bent and extends along the axis. The iron core set is coupled to the at least one primary side conductive piece and the at least one secondary side conductive piece. 
     According to an embodiment of the invention, the power transformer further includes a board, a first heat dissipation member, and a second heat dissipation member. The iron core set, the at least one primary side conductive piece, and the at least one secondary side conductive piece are located on the board, the board includes a first hole, a second hole, a third hole, and a fourth hole, wherein the first conductive strip pin passes through the first hole, and the second conductive strip pin passes through the second hole. The first heat dissipation member has a first end and a second end opposite to each other. The first end is connected to the first conductive strip pin and the second end passes through the third hole. The second heat dissipation member has a third end and a fourth end opposite to each other. The third end is connected to the second conductive strip pin and the fourth end passes through the fourth hole. 
     According to an embodiment of the invention, the power transformer further includes a plurality of center tap conductive strip pins. The at least one secondary side conductive piece includes a plurality of secondary side conductive pieces, the first conductive strip pin extends from one of the secondary side conductive pieces, the second conductive strip pin extends from another one of the secondary side conductive pieces, and the center tap conductive strip pins respectively extend from the secondary side conductive pieces, and the center tap conductive strip pins are bent and extend along the axis. 
     According to an embodiment of the invention, the at least one primary side conductive piece includes a plurality of primary side conductive pieces, the at least one secondary side conductive piece includes a plurality of secondary side conductive pieces, and the primary side conductive pieces and the secondary side conductive pieces are alternately stacked respectively. 
     According to an embodiment of the invention, each of the at least one primary side conductive piece is in a flat annular shape, each of the at least one secondary side conductive piece is a flat annular shape, the iron core set penetrates through the at least one primary side conductive piece and the at least one secondary side conductive piece. 
     A circuit board module according to an embodiment of the invention includes a circuit board, a plurality of rectifier transistors, and a power transformer. The circuit board includes a first surface and a second surface opposite to each other. The rectifier transistors are disposed on the first surface of the circuit board, and each of the rectifier transistors includes a drain. The power transformer is disposed on the second surface of the circuit board. The power transformer includes at least one primary side conductive piece, at least one secondary side conductive piece, a first conductive strip pin, a second conductive strip pin, and an iron core set. The at least one secondary side conductive piece is stacked to the at least one primary side conductive piece along an axis. The first conductive strip pin extends from the at least one secondary side conductive piece, and the first conductive strip pin is bent and extends along the axis. The first conductive strip pin is conductive to a portion of the drains of the rectifier transistors. The second conductive strip pin extends from the at least one secondary side conductive piece, and the second conductive strip pin is bent and extends along the axis. The second conductive strip pin is conductive to another portion of the drains of the rectifier transistors. The iron core set is coupled to the at least one primary side conductive piece and the at least one secondary side conductive piece. 
     According to an embodiment of the invention, an orthogonal projection of the power transformer on the circuit board is overlapped with an orthogonal projection of the rectifier transistors on the circuit board. 
     According to an embodiment of the invention, the power transformer further includes a board, a first heat dissipation member, and a second heat dissipation member. The iron core set, the at least one primary side conductive piece, and the at least one secondary side conductive piece are located on the board, the board includes a first hole, a second hole, a third hole, and a fourth hole, the first conductive strip pin passes through the first hole, and the second conductive strip pin passes through the second hole. The first heat dissipation member has a first end and a second end opposite to each other. The first end is connected to the first conductive strip pin and the second end passes through the third hole. The second heat dissipation member has a third end and a fourth end opposite to each other. The third end is connected to the second conductive strip pin and the fourth end passes through the fourth hole. 
     According to an embodiment of the invention, the circuit board includes a plurality of first pads and a plurality of second pads located on the first surface, the first pads are located at a side of the rectifier transistors, the second pads are located at another side of the rectifier transistors, the first pads and the second pads are respectively conductive to the drains of the rectifier transistors, the first conductive strip pin and the second conductive strip pin are respectively inserted to the circuit board and connected to the first pads, and the first heat dissipation member and the second heat dissipation member are respectively inserted to the circuit board and connected to the second pads. 
     According to an embodiment of the invention, the circuit board module further includes a fan, disposed on the second surface of the circuit board, and the first conductive strip pin and the second conductive strip pin of the power transformer face toward the fan. 
     According to an embodiment of the invention, the axis is parallel to a normal direction of the circuit board. 
     According to an embodiment of the invention, the at least one primary side conductive piece includes a plurality of primary side conductive pieces, the at least one secondary side conductive piece includes a plurality of secondary side conductive pieces, and the primary side conductive pieces and the secondary side conductive pieces are alternately stacked respectively. 
     According to an embodiment of the invention, the power transformer further includes a plurality of center tap conductive strip pins. The at least one secondary side conductive piece includes a plurality of secondary side conductive pieces. The first conductive strip pin extends from one of the secondary side conductive pieces, and the second conductive strip pin extends from another one of the secondary side conductive pieces. The center tap conductive strip pins respectively extend from the secondary side conductive pieces, and are the center tap conductive strip bent and extend along the axis, and are inserted to the circuit board. 
     Each of the at least one primary side conductive piece is in a flat annular shape, each of the at least one secondary side conductive piece is a flat annular shape, the iron core set penetrates through the at least one primary side conductive piece and the at least one secondary side conductive piece. 
     Based on the above, the primary side conductive pieces and the secondary side conductive pieces of the power transformer according to the embodiments of the invention are stacked along the axis. In addition, the first conductive strip pin and the second conductive strip pin extend from the secondary side conductive pieces, and are bent and extend along the axis. In the circuit board module, according to the embodiments of the invention, the first conductive strip pin and the second conductive strip pin of the power transformer are conductive to the drains of the rectifier transistors by making use of the property that the drains of the rectifier transistors and the first conductive strip pin and the second conductive strip pin of the power transformer are at the same potential. In this way, when the rectifier transistors are in operation, the heat generated from the rectifier transistors is taken to the first conductive strip pin and the second conductive strip pin of the power transformer. In other words, in addition to transmitting electrical signals, the first conductive strip pin and the second conductive strip pin of the power transformer are further able to dissipate heat from the rectifier transistors. In this way, the rectifier transistors do not require an additional heatsink, and the overall size and weight of the device (e.g., a power supply) having the circuit board module can be reduced. 
     In order to make the aforementioned and other features and advantages of the invention comprehensible, several exemplary embodiments accompanied with figures are described in detail below. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
         FIG. 1  is a schematic view illustrating a power transformer according to an embodiment of the invention. 
         FIG. 2  is a schematic view of the power transformer of  FIG. 1  from another perspective. 
         FIG. 3  is a schematic exploded view of the power transformer of  FIG. 1 . 
         FIG. 4  is a schematic top view illustrating a board, a first heat dissipation member, and a second heat dissipation member of  FIG. 1 . 
         FIG. 5  is a partial schematic view illustrating a circuit board module according to an embodiment of the invention. 
         FIG. 6  is a schematic view illustrating another surface of the circuit board module of  FIG. 5 . 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
       FIG. 1  is a schematic view illustrating a power transformer according to an embodiment of the invention.  FIG. 2  is a schematic view of the power transformer of  FIG. 1  from another perspective.  FIG. 3  is a schematic exploded view of the power transformer of  FIG. 1 .  FIG. 4  is a schematic top view illustrating a board, a first heat dissipation member, and a second heat dissipation member of  FIG. 1 . 
     Referring to  FIGS. 1 to 4 , a power transformer  100  of the embodiment includes at least one primary side conductive piece  110 , at least one secondary side conductive piece  120 , a first conductive strip pin  130 , a second conductive strip pin  140 , and an iron core set  160 . The primary side conductive piece  110  and the secondary side conductive piece  120  are stacked along an axis A. In the embodiment, the at least one primary side conductive piece  110  includes multiple primary side conductive pieces  110 , and the at least one secondary side conductive piece  120  includes multiple secondary side conductive pieces  120 . In addition, the primary side conductive pieces  110  and the secondary side conductive pieces  120  are alternately stacked respectively. Further, in other embodiments, the numbers of the primary side conductive pieces  110  and the secondary side conductive pieces  120  and the way that the primary side conductive pieces  110  and the secondary side conductive pieces  120  are stacked are not limited to the above. 
     As shown in  FIG. 3 , in the embodiment, the first conductive strip pin  130  extends from one of the secondary side conductive pieces  120 , and the first conductive strip pin  130  is bent and extends along the axis A. The second conductive strip pin  140  extends from another one of the secondary side conductive pieces  120 , and the second conductive strip pin  140  is bent and extends along the axis A. Further, in other embodiments, the first conductive strip pin  130  and the second conductive strip pin  140  may also extend from the same secondary side conductive piece  120 . Moreover, in the embodiment, the power transformer  100  may optionally include a plurality of center tap conductive strip pins  150 . The center tap conductive strip pins  150  respectively extend from the secondary side conductive pieces  120 , and the center tap conductive strip pins  150  are bent and extend along the axis A. 
     Specifically, as shown in  FIG. 3 , in the embodiment, the power transformer  100  includes two secondary side conductive pieces  120 . The first conductive strip pin  130  and one of the center tap conductive strip pins  150  extend from the secondary side conductive piece  120  at the lower side and passes beside the primary side conductive piece at the lower side  110  after being bent. The second conductive strip pin  140  and the other center tap conductive strip pin  150  extend from the secondary side conductive piece  120  at the upper side, and pass beside the primary side conductive piece  110  and the secondary side conductive piece  120  at the lower side. 
     Besides, in the embodiment, the iron core set  160  is coupled to the primary side conductive pieces  110  and the secondary side conductive pieces  120 . In the embodiment, each of the primary side conductive pieces  110  the secondary side conductive pieces  120  is in a flat annular shape. In other words, a hole is at the center of each of the primary side conductive pieces  110 , and a hole is at the center of each of the secondary side conductive pieces  120 . The iron core set  160  is divided into an upper part and a lower part which together penetrate through the primary side conductive pieces  110  and the secondary side conductive pieces  120  and are coupled to the primary side conductive pieces  110  and the secondary side conductive pieces  120 . Further, in other embodiments, the form of the iron core set  160  is not limited thereto. 
     Besides, as shown in  FIGS. 1 to 4 , the power transformer  100  of the embodiment further includes a board  170 , a first heat dissipation member  180 , and a second heat dissipation member  185 . The iron core set  160 , the primary side conductive pieces  110 , and the secondary side conductive pieces  120  are located on the board  170 . As shown in  FIG. 4 , the board  170  includes a first hole  171 , a second hole  172 , a third hole  173 , a fourth hole  174 , and a fifth hole  174 . In the embodiment, the first heat dissipation member  180  includes a first end  182  and a second end  184  opposite to each other. The first end  182  passes through the first hole  171  and the second end  184  passes through the third hole  173 . The second heat dissipation member  185  includes a third end  186  and a fourth end  188  opposite to each other. The third end  186  passes through the second hole  172  and the fourth end  188  passes through the fourth hole  174 . As shown in  FIGS. 1 to 3 , the first conductive strip pin  130  passes through the first hole  171 , and the first end  182  of the first heat dissipation member  180  is connected to the first conductive strip pin  130 . The second conductive strip pin  140  passes through the second hole  172 , and the third end  186  of the second heat dissipation member  185  is connected to the second conductive strip pin  140 . In addition, the center tap conductive strip pins  150  pass through a fifth hole  175 . 
     Further, in the following description, how the power transformer  100  of the embodiment dissipates the heat from the rectifier transistor will be described. 
       FIG. 5  is a partial schematic view illustrating a circuit board module according to an embodiment of the invention.  FIG. 6  is a schematic view illustrating another surface of the circuit board module of  FIG. 5 . Referring to  FIGS. 5 and 6 ,  FIG. 5  illustrates a partial region on a first surface  21  of a circuit board  20 , and  FIG. 6  illustrates a corresponding region on a second surface  22  of the circuit board  20 . 
     In the embodiment, a circuit board module  10  includes the circuit board  20 , a plurality of rectifier transistors  30  (as shown in  FIG. 5 ), and the power transformer  100  (as shown in  FIG. 6 ). The circuit board  20  includes the first surface  21  (as shown in  FIG. 5 ), and the second surface  22  (as shown in  FIG. 6 ). As shown in  FIG. 5 , the rectifier transistors  30  are disposed on the first surface  21  of the circuit board  20 , and each of the rectifier transistors  30  includes at least one drain  32 . In the embodiment, the circuit board module  10  is described with an example with six rectifier transistors  30 , where the rectifier transistors  30  are divided into an upper row and a lower row, and each of the rectifier transistors  30  includes four drains  32 . However, the number and the configuration relationship of the rectifier transistors  30  of the circuit board module  10  and the number of the drains  32  of each of the rectifier transistors  30  are not limited to the example. 
     Besides, in the embodiment, the circuit board  20  includes a plurality of first pads  23  located on the first surface  21 . The first pads  23  are located at a side of the rectifier transistors  30 . The first pads  23  are respectively conductive to the drains  32  of the rectifier transistors  30 . Specifically, in the embodiment, the number of the first pads  23  is two. The drains  32  of the three rectifier transistors  30  located at the upper row are connected to the first pad  23  at the upper side through a circuit  26 , and the drains  32  of the three rectifier transistors  30  located at the lower row are connected to the first pad  23  at the lower side through the circuit  26 . 
     As shown in  FIG. 6 , the power transformer  100  (labeled in  FIG. 1 ) is disposed on the second surface  22  of the circuit board  20 . In the embodiment, the axis A (labeled in  FIG. 1 ) along which the first conductive strip pin  130  and the second conductive strip pin  140  of the power transformer  100  extend is parallel to a normal direction of the circuit board  20 . In other words, the primary side conductive pieces  110  and the secondary side conductive pieces  120  (labeled in  FIG. 1 ) of the power transformer  100  are stacked along the normal direction of the circuit board  20 . As shown in  FIG. 6 , the orthogonal projection of the power transformer  100  on the circuit board  20  is overlapped with the orthogonal projection of the rectifier transistors  30  on the circuit board  20 . 
     As shown in  FIG. 6 , in the embodiment, the first conductive strip pin  130  extends along the direction pointing into the drawing and is inserted to the circuit board  20 . In addition, the first conductive strip pin  130  is connected to the first pad  23  located at a upper left position on the first surface  21  of the circuit board  20 , and is conductive to the drains  32  of the rectifier transistors  30  of the upper row. The second conductive strip pin  140  extends along the direction pointing into the drawing and is inserted to the circuit board  20 . In addition, the second conductive strip pin  140  is connected to the first pad  23  located at a lower left position on the first surface  21  of the circuit board  20  and is conductive to the drains  32  of the rectifier transistors  30  at the lower row. 
     In the circuit board module  10  of the embodiment, the first conductive strip pin  130  and the second conductive strip pin  140  of the power transformer  100  are conductive to the drains  32  of the rectifier transistors  30  by making use the property that the drains  32  of the rectifier transistors  30  and the first conductive strip pin  130  and the second conductive strip pin  140  of the power transformer  100  are at the same potential. In this way, while the rectifier transistors  30  are in operation, the heat generated from the rectifier transistors  30  are operating is taken to the first conductive strip pin  130  and the second conductive strip pin  140  of the power transformer  100 . In other words, in addition to transmitting electrical signals, the first conductive strip pin  130  and the second conductive strip pin  140  of the power transformer  100  are further able to dissipate heat from the rectifier transistors  30 . 
     It should be noted that, as shown in  FIG. 5 , in order to facilitate the efficiency of heat dissipation, the circuit board  20  of the embodiment may further optionally include a plurality of second pads  24  located on the first surface  21 . The first pads  23  and the second pads  24  are respectively located at two opposite sides of the rectifier transistors  30 . The second pads  24  are respectively conductive to the drains  32  of the rectifier transistors  30 . Specifically, in the embodiment, the number of the second pads  24  is two. The drains  32  of the three rectifier transistors  30  located at the upper row are connected to the second pad  24  at the upper side through the circuit  26 , and the drains  32  of the three rectifier transistors  30  located at the lower row are connected to the second pad  24  at the lower side through the circuit  26 . Besides, in the embodiment, the circuit board  20  may further optionally include a third pad  25  located on the first surface  21 . The center tap conductive strip pins  150  of the power transformer  100  may be inserted to the circuit board  20  and connected to the third pad  25 . 
     In the embodiment, the first pads  23  and the second pads  24  are respectively disposed beside two opposite sides of the rectifier transistors  30 . Since each row has three rectifier transistors  30 , the distance between the rectifier transistor  30  on the right and the first pad  23  is longer than the distance between the rectifier transistor  30  on the right and the second pad  24 . Therefore, when the rectifier transistor  30  on the right is in operation, the current may tend to flow toward the second pad  24 , and the heat generated from the rectifier transistor  30  on the right also tends to be transmitted toward the second pad  24 . By the design of disposing the first pads  23  and the second pads  24  beside two opposite sides of the rectifier transistors  30 , the rectifier transistors  30  are able to transmit currents and heat through the first pads  23  and the second pads  24  on the two opposite sides. 
     Back to  FIGS. 1, 2, and 6 , in the embodiment, the first end  182  of the first heat dissipation member  180  and the first conductive strip pin  130  of the power transformer  100  are inserted to the circuit board  20  together and connected to the first pad  23  located at the upper left position on the first surface  21  of the circuit board  20 . The second end  184  of the first heat dissipation member  180  of the power transformer  100  is inserted to the circuit board  20  and connected to the second pad  24  located at the upper right position on the first surface  21  of the circuit board  20 . The third end  186  of the second heat dissipation member  185  and the second conductive strip pin  140  of the power transformer  100  are inserted to the circuit board  20  together and connected to the first pad  23  located at the lower left position on the first surface  21  of the circuit board  20 . The fourth end  188  of the second heat dissipation member  185  of the power transformer  100  is inserted to the circuit board  20  and connected to the second pad  24  located at the lower right position on the first surface  21  of the circuit board  20 . 
     Therefore, referring to  FIGS. 5 and 6 , a portion of the heat generated by the rectifier transistors  30  located at the upper row on the first surface  21  of the circuit board  20  may be transmitted leftward to the first conductive strip pin  130  sequentially via the circuit  26 , the first pad  23 , and the first end  182  of the first heat dissipation member  180 , and a portion of the heat generated by the rectifier transistors  30  located at the upper row on the first surface  21  of the circuit board  20  may be further transmitted rightward to the first conductive strip pin  130  sequentially via the circuit  26 , the second pad  24 , the second end  184  of the first heat dissipation member  180 , the first heat dissipation member  180 , and the first end  182  of the first heat dissipation member  180 . 
     Similarly, a portion of the heat generated by the rectifier transistors located at the lower row on the first surface  21  of the circuit board  20  may be transmitted leftward to the second conductive strip pin  140  sequentially via the circuit  26 , the first pad  23 , and the third end  186  of the second heat dissipation member  185 , and a portion of the heat generated by the rectifier transistors  30  located at the lower row on the first surface  21  of the circuit board  20  may be further transmitted rightward to the second conductive strip pin  140  sequentially via the circuit  26 , the second pad  24 , the fourth end  188  of the second heat dissipation member  185 , the second heat dissipation member  185 , and the third end  186  of the second heat dissipation member  185 . 
     In the embodiment, the power transformer  100  offers a large heat dissipation area by making use of the first conductive strip pin  130 , the second conductive strip pin  140 , the first heat dissipation member  180 , and the second heat dissipation member  185 , so as to facilitate heat dissipation. Besides, as shown in  FIG. 6 , the circuit board module  10  of the embodiment may further optionally include a fan  40  disposed on the second surface  22  of the circuit board  20 . The air flow (which may be the air blown from or drawn to the fan  40 ) generated by the fan  40  is capable of quickly taking away the heat transmitted to the first conductive strip pin  130  and the second conductive strip pin  140 , thereby cooling off the rectifier transistors  30 . In the embodiment, the first conductive strip pin  130  and the second conductive strip pin  140  of the power transformer  100  face toward the fan  40 . However, in other embodiments, the position relationship among the first conductive strip pin  130 , the second conductive strip pin  140 , and the fan  40  is not limited thereto. In addition, the fan  40  in  FIG. 6  is merely shown for an illustrative purpose. The type of the fan  40  and the distance between the fan  40  and the power transformer  100  are not limited thereto. 
     In view of the foregoing, the primary side conductive pieces and the secondary side conductive pieces of the power transformer according to the embodiments of the invention are stacked along the axis. In addition, the first conductive strip pin and the second conductive strip pin extend from the secondary side conductive pieces, and are bent and extend along the axis. In the circuit board module, according to the embodiments of the invention, the first conductive strip pin and the second conductive strip pin of the power transformer are conductive to the drains of the rectifier transistors by making use of the property that the drains of the rectifier transistors and the first conductive strip pin and the second conductive strip pin of the power transformer are at the same potential. In this way, when the heat generated from the rectifier transistors are in operation, the heat is taken to the first conductive strip pin and the second conductive strip pin of the power transformer. In other words, in addition to transmitting electrical signals, the first conductive strip pin and the second conductive strip pin of the power transformer are further able to dissipate heat from the rectifier transistors. In this way, the rectifier transistors do not require an additional heatsink, and the overall size and weight of the device (e.g., a power supply) having the circuit board module can be reduced. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.