JP2011077328A - Transformer and switching power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the characteristics of heat dissipation of heat generated by a primary-side coil. <P>SOLUTION: A coil component 10 constituting a transformer 140 of a DC-DC converter 100 includes a heat conduction region 29 provided to a primary-side coil substrate 20. The heat conduction region 29 and a projection part 113 of a base plate 102 as a heat dissipation member are thermally connected to each other, to excellently perform heat transmission of heat generated by a primary-side coil conductor of the primary-side coil substrate 20, specifically, heat generated by a second coil part 214 and a third coil part 216 forming the primary-side coil conductor of the transformer 140 to the base plate 102. Namely, the heat generated by the coil on the side of the primary-side coil substrate 20 can be dissipated to the base plate 102 not through secondary-side coils 30 and 40, and thereby heat dissipation effects of the primary-side coil substrate 20 can be enhanced. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a transformer and a switching power supply device.

  Conventionally, various in-vehicle switching power supply devices used for hybrid cars, electric vehicles, and the like have been proposed and put into practical use. As a transformer used in these switching power supply devices, for example, the one described in Patent Document 1 is known. The thin high-current transformer described in Patent Document 1 is a high-powered sheet-shaped conductor in which a coil pattern is formed between two coils on the low voltage side (secondary side) obtained by punching a conductor plate. The voltage side (primary side) coil is sandwiched.

JP 2004-303857 A

  However, in the transformer described in Patent Document 1, the heat generated in the high-voltage side coil due to the flow of a large current or the like is dissipated through the secondary side coil sandwiching the primary side coil. The heat generated by the secondary coil may not be sufficiently dissipated.

  The present invention has been made in view of the above, and an object of the present invention is to provide a transformer with improved heat dissipation of heat generated by a primary coil, and a switching power supply device including the transformer. To do.

  In order to achieve the above object, a transformer according to the present invention is a transformer connected to a primary side circuit board to which a switching element is connected, and is connected to the primary side circuit board and has an insulating property. A board formed by a member, a primary coil conductor, a primary coil board having conductor wiring embedded in the board and electrically connected to the primary coil conductor, and a conductor plate. Two secondary coils sandwiching the primary coil substrate from both sides along the thickness direction, and the primary coil substrate overlaps with the two secondary coils when viewed from the thickness direction. It is characterized in that it is thermally connected to the heat radiating member in the heat transfer region that does not become.

  In the above transformer, the primary coil substrate has a heat transfer region that does not overlap with the two secondary coils when viewed from the thickness direction, and is thermally connected to the heat dissipation member in this heat transfer region. Yes. For this reason, the heat generated in the primary coil conductor of the primary coil substrate is transferred to the heat radiating member through the heat transfer region without passing through the secondary coil, and is generated in the primary coil conductor. Heat can be effectively dissipated.

  Moreover, it is preferable that the conductor wiring is embedded at a position corresponding to the heat transfer region of the primary coil substrate when viewed from the thickness direction.

  By having the above configuration, the distance between the conductor wiring and the heat transfer area is reduced, so the heat generated in the primary coil conductor and transmitted to the conducting wire is efficiently radiated to the heat dissipation member via the heat transfer area. Is done.

  A switching power supply according to the present invention includes the above-described transformer. In this case, heat generated in the primary coil conductor is transferred to the heat radiating member via the heat transfer region. Therefore, a switching power supply device that can effectively dissipate heat generated in the primary coil conductor of the transformer is obtained.

  Here, specifically as a structure which exhibits said effect | action more effectively, the switching power supply device has the aspect further equipped with the base plate which mounts a trans | transformer while a thermal radiation member comprises the part.

  Moreover, said switching power supply device can be set as the aspect further equipped with the resonance coil connected in series with a primary side coil conductor inside the primary side coil board | substrate.

  In the case of the above configuration, since the primary coil substrate includes the resonance coil connected in series with the primary coil conductor, the heat generated in the resonance coil is generated from the heat transfer region of the primary coil substrate. Heat is transferred to the heat radiating member. Therefore, according to the primary coil substrate, the heat generated in the resonance coil can be effectively radiated.

  Here, the switching power supply device described above forms a magnetic path by being inserted into the central portion of the resonance coil and the first magnetic core that magnetically connects the primary coil conductor and the secondary coil of the transformer. A second magnetic core, and the first magnetic core and the second magnetic core extend in a direction intersecting each other when viewed from the thickness direction, and the heat transfer region is the first magnetic core. It can be set as the aspect provided between the 1 magnetic body core and the 2nd magnetic body core.

  With the above configuration, the heat transfer region can be provided at a position close to both the transformer and the resonance coil, and both the heat generated in the primary coil conductor of the transformer and the heat generated in the resonance coil are effective. Heat can be radiated and the heat radiation effect can be further enhanced.

  ADVANTAGE OF THE INVENTION According to this invention, the transformer with which the heat dissipation of the heat which generate | occur | produced with the coil of the primary side was improved, and the switching power supply device comprised including this transformer are provided.

It is a perspective view explaining the structure of the DC-DC converter which concerns on this embodiment. It is a circuit diagram of the DC-DC converter of FIG. It is a perspective view which shows the structure of the coil components which comprise the DC-DC converter of FIG. FIG. 4 is an exploded perspective view of the coil component of FIG. 3. It is a disassembled perspective view of the structure except the 1st magnetic body core and the 2nd magnetic body core among the coil components of FIG. It is a figure which shows typically arrangement | positioning of the conductor in a primary side coil board | substrate. It is a perspective view which shows the shape of the part which accommodates coil components among housings. It is a VIII-VIII arrow line view of the state where the coil components and the primary side circuit board were stored with respect to the case of FIG. It is IX-IX arrow line view of the state in which the coil components and the primary side circuit board were accommodated with respect to the housing | casing of FIG. It is a disassembled perspective view explaining the structure of a coil component and a primary side circuit board. It is the perspective view which looked at the coil component and primary side circuit board of FIG. 10 from the back surface side.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a perspective view illustrating a configuration of a DC-DC converter 100 that is a switching power supply device according to the present embodiment, and FIG. 2 is a circuit diagram of the DC-DC converter 100 of FIG. The DC-DC converter 100 shown in FIGS. 1 and 2 converts, for example, a high-voltage DC input voltage Vin supplied from a high-voltage battery or the like that stores a voltage of about 100 V to 500 V into a low-voltage DC output voltage Vout, and has a voltage of 12 to 16 V. It has a function of supplying a low voltage battery or the like that stores a certain voltage.

  As shown in FIG. 1, the DC-DC converter 10 has a switching circuit 120, an input smoothing circuit (input filter) 130, a transformer 140, a rectifier circuit 150, and a base plate 102 that forms the bottom surface of the casing 101. The smoothing circuit 160 including the choke coil 161 and the output smoothing circuit (output filter) 162 is fixed.

  As shown in FIG. 2, the circuit configuration of the DC-DC converter 100 includes a switching circuit 120 and an input smoothing circuit 130 provided between a primary high voltage line 121 and a primary low voltage line 122, A transformer 140 having secondary and secondary coils 141 and 142 (142A and 142B), a rectifier circuit 150 connected to the secondary coil 142, and a smoothing circuit 160 connected to the rectifier circuit 150 are provided. Yes.

  The switching circuit 120 is configured by a full-bridge circuit composed of switching elements S1 to S4 (the four switching elements S1 to S4 are referred to as switching elements 124), and is supplied from, for example, a drive circuit (not shown). In accordance with the drive signal, the DC input voltage Vin applied between the input terminals T1 and T2 is converted into an input AC voltage. As the switching elements S1 to S4, for example, a field effect transistor (FET), an IGBT (Insulated Gate Bipolar Transistor), or the like is used. Further, the circuit of the DC-DC converter 100 is further provided with a resonance coil 125 connected in series with the switching element 124 of the switching circuit 120. This resonant coil 125 is also connected in series with the primary side coil conductor 141 of the transformer 140, and the capacitance (Fig. 1) is connected in parallel to the inductance of the own coil and each of the switching elements 124 (S1 to S4) constituting the switching circuit 120. (Not shown) function to reduce the switching loss of the switching element.

  The input smoothing capacitor 130 smoothes the DC input voltage Vin input from the input terminals T1 and T2. The transformer 140 transforms the input AC voltage generated by the switching circuit 120 and outputs an output AC voltage. Note that the turn ratio of the primary and secondary coils 141 and 142 is appropriately set depending on the transformation ratio. In the DC-DC converter 100 according to the present embodiment, the number of turns of the primary coil conductor 141 is larger than the number of turns of the secondary coil 142. The secondary coil 142 of the DC-DC converter 100 according to the present embodiment is of a center tap type, and includes a secondary coil 142A on the rectifier diode 151A side, a secondary coil 142B on the rectifier diode 151B side, Is connected to the output terminal T3 via the output line LO.

  The rectifier circuit 150 is a single-phase full-wave rectifier type composed of rectifier diodes 151A and 151B. The cathodes of the rectifier diodes 151A and 151B are connected to the secondary coils 142A and 142B, respectively, while the anode is connected to the ground line LG and led to the output terminal T4. Thus, the rectifier circuit 150 individually rectifies the output AC from the transformer 140 to generate a DC voltage.

  The smoothing circuit 160 includes a choke coil 161 and an output smoothing capacitor 162. The choke coil 161 is inserted into the output line LO. The output smoothing capacitor 162 is connected between the choke coil 161 and the ground line LG in the output line LO. As a result, the smoothing circuit 160 smoothes the DC voltage rectified by the rectifying circuit 150 to generate the DC output voltage Vout, and supplies the DC output voltage Vout from the output terminals T3 and T4 to a low-voltage battery or the like.

  In the DC-DC converter 100 configured as described above, the DC input voltage Vin supplied from the primary side input terminals T1 and T2 is switched to generate the input AC voltage, and the primary side coil conductor of the transformer 140 is switched. 141. Then, the generated input AC voltage is transformed and output from the secondary coil 142 as an output AC voltage. Then, the output AC voltage is rectified by the rectifier circuit 150 and smoothed by the smoothing circuit 160, and is output as the DC output voltage Vout from the secondary side output terminals T3 and T4.

  The base plate 102 of the housing 101 to which the DC-DC converter 100 is fixed has a function as a heat radiating member that cools each element on the base plate 102 and a conductive wire, a circuit board, and the like connecting them. Specifically, the housing 101 including the base plate 102 is made of a metal such as aluminum, and on the back side of the base plate 102 (the lower side in FIG. 1: the side opposite to the surface on which each element or substrate is fixed). A fin for heat dissipation is attached. The heat-dissipating fins are air-cooled and the back surface side of the base plate 102 is cooled, so that a high current flows through each element of the DC-DC converter 100 fixed to the front surface side of the base plate 102, whereby each element. Is absorbed by the base plate 102 and radiated from the back side of the base plate 102 to the outside. Thus, the base plate 102 functions as a heat sink. In addition, the base plate 102 and the fin for heat dissipation may be comprised from the mutually different member as mentioned above, and may be comprised from the same member. Further, instead of a configuration in which fins for heat dissipation by air cooling are attached, a coolant flow path for water cooling is provided on the back surface side of the base plate 102, and the back surface side of the base plate 102 is water-cooled, so It is good also as a structure which thermally radiates heat.

  In addition, the DC-DC converter 100 according to the present embodiment includes an exterior cover that covers the casing 101, an input-side and output-side terminal block for electrical connection with external devices, and the above-described elements. And a drive circuit for controlling the drive of each element by transmitting a drive signal. In the DC-DC converter 100, the above-described circuits function, whereby the high-voltage DC input voltage Vin input from the input-side terminal is converted into the low-voltage DC output voltage Vout and output from the output-side terminal. It has a function.

  Next, the coil component 10 constituting the DC-DC converter 100 shown in FIGS.

  3 is a perspective view showing the structure of the coil component 10 constituting the DC-DC converter 100 of FIG. 1, FIG. 4 is an exploded perspective view of the coil component 10 of FIG. 3, and FIG. 2 is an exploded perspective view of a configuration excluding the first magnetic core 70 and the second magnetic core 80 in the coil component 10 of FIG. As shown in FIGS. 3 to 5, the coil component 10 includes a primary coil substrate 20, secondary coils 30 and 40, a first magnetic core 70, a second magnetic core 80, These function as the resonance coil 125 and the transformer 140 of the DC-DC converter 100 shown in FIGS. 1 and 2 (details of the functions will be described later).

  The primary coil substrate 20 is a flat substrate in which a conductor made of a metal such as copper is embedded in a substrate made of an insulating member such as an electrically insulating resin. The primary side coil substrate 20 is formed by alternately laminating insulating members and coils and conductors serving as conductor wirings, and these conductors are provided on the upper surface side of the primary side coil substrate 20. The first terminal portion 21 and the second terminal portion 22 can be electrically connected to an external device or the like.

  Further, the primary coil substrate 20 includes a circular opening 23 penetrating in the thickness direction (Z-axis direction shown in FIG. 4) for forming the resonance coil 125. An arc portion 23A formed of an arcuate insulator is provided around the opening 23 along the thickness direction. Of the outer peripheral portion of the arc portion 23A, an area extending in the negative direction of the Y axis from the center of the opening 23 is provided with an opening 24 along the outer peripheral portion of the arc portion 23A, and the outer peripheral portion of the arc portion 23A. Of these, a region extending in the positive direction of the Y axis from the center of the opening 23 is an exposed portion 25 exposed to the outside, and this exposed portion 25 forms a part of the side wall of the primary side coil substrate 20. Further, as shown in FIG. 5, the primary side coil substrate 20 includes circular openings 26 and 27 penetrating in the thickness direction for forming the transformer 140. The openings 26 and 27 are arranged in parallel along the X-axis direction shown in FIG.

  Here, the arrangement of the conductors inside the primary coil substrate 20 will be described with reference to FIG. FIG. 6 is a diagram schematically showing the arrangement of conductors in the primary coil substrate 20. The primary coil substrate 20 is a four-layer substrate in which three insulating layers made of a resin such as an epoxy resin and four conductor layers sandwiching them are stacked in the thickness direction (Z-axis direction). In the primary coil substrate 20, two conductor layers inside the multilayer substrate excluding the conductor layers on the front surface side and the back surface side (the second layer and the third layer are defined as the first conductor layer on the front surface side). Layer) is used as a conductor wiring layer for forming a coil, and a conductor in the primary coil substrate 20 is formed. In the above four-layer substrate, the thickness of the insulating layer on the front surface side of the three insulating layers is equal to the thickness of the insulating layer on the back surface side, and the thickness of the first layer and the fourth layer of the four conductor layers are the same. The thickness is equal, and the thickness of the second layer is equal to the thickness of the third layer. Further, conductors other than the periphery of the first terminal portion 21 and the second terminal portion 22 are removed from the conductor layers on the front surface side and the back surface side. Therefore, on the front surface side and the back surface side of the primary side coil substrate 20 according to the present embodiment, the region excluding the periphery of the first terminal portion 21 and the second terminal portion 22 is covered with the insulating layer.

  As shown in FIG. 6, the first coil portion 212 that winds around the opening 23 and the second coil that winds around the opening 26 are formed on the two conductor wiring layers inside the primary side coil substrate 20. A coil part 214 and a third coil part 216 wound around the opening 27 are formed by a conductor pattern or the like. Further, inside the primary side coil substrate 20, between the first terminal portion 21 and one end of the first coil portion 212, between the other end of the first coil portion 212 and one end of the second coil portion 214, Connection portions 211, 213, 215, and 217 connecting the other end of the second coil portion 214 and one end of the third coil portion 216, and connecting the other end of the third coil portion 216 and the second terminal portion 22, respectively. Is formed by a conductor pattern or the like. FIG. 6 is a diagram schematically showing the arrangement of conductors and their connection relationship, and the conductors constituting the first coil part 212, the second coil part 214, and the third coil part 216 are indicated by broken lines in FIG. As described above, the first coil part region 212A, the second coil part region 214A, and the third coil part region 216A provided around the openings 23, 26, and 27 are provided. In FIG. 6, the first coil portion 212, the second coil portion 214, and the third coil portion 216 are each formed by winding the conductor around the opening in each layer of the two conductor wiring layers. Although the configuration in which the periphery of the opening is wound by two turns has been described, a configuration in which the opening is wound a plurality of times in each layer of the two conductor wiring layers may be employed.

  In the primary side coil substrate 20 having the above-described configuration, the current input from the first terminal portion 21 of the primary side coil substrate 20 to the primary side coil substrate 20 reaches the inside of the arc portion 23A via the connection portion 211. When the primary coil substrate 20 is viewed from the upper part in the thickness direction, it flows through the first coil part 212 wound around the opening 23 clockwise from the upper side to the lower side, and is connected from the first coil part 212. It reaches the second coil part 214 via the part 213. The current that has reached one end of the second coil portion 214 is wound around the opening 26 clockwise from the bottom to the top when the primary coil substrate 20 is viewed from the upper part in the thickness direction. It flows through the second coil part 214 and reaches the third coil part 216 from the second coil part 214 via the connection part 215. Then, the current that has reached one end of the third coil portion 216 is wound around the periphery of the opening 26 clockwise from the direction when the primary coil substrate 20 is viewed from the upper part in the thickness direction. It flows through the coil part 214 and reaches the third coil part 216 through the connection part 215 from the second coil part 214.

  3 and 4, the secondary side coils 30 and 40 are formed by punching a conductive plate such as copper, respectively, and the primary side coil is formed from both sides along the thickness direction of the primary side coil substrate 20. It arrange | positions so that a part of board | substrate 20 may be pinched | interposed. Specifically, the secondary coil 30 is provided above the primary coil substrate 20 (the positive direction of the Z axis), and the secondary coil 40 is below the primary coil substrate 20 (Z (In the negative direction of the shaft).

  The secondary coil 30 has a so-called S-shape when viewed from above in FIG. 5 and has two openings 36 and 37 arranged in parallel along the X-axis direction. These openings 36 and 37 have a larger inner diameter than the openings 26 and 27 provided in the primary coil substrate 20, and the primary coil substrate 20 and the secondary coil 30 are overlapped with each other when the primary coil substrate 20 and the secondary coil 30 are overlapped. Provided to communicate with the openings 26 and 27 of the side coil substrate 20. The secondary coil 30 is shaped to circulate the openings 36 and 37 in different directions in a C shape. A slit 38 extending in the negative direction of the Y axis from the opening 36 to the outer periphery of the secondary coil 30 and a slit 39 extending in the positive direction of the X axis from the opening 37 to the outer periphery of the secondary coil 30 are provided.

  In addition, a first terminal portion 31 protruding outward with respect to the central axis B of the opening 37 is provided at one end portion of the S-shaped secondary coil 30, and the other end portion of the secondary coil 30. Is provided with a second terminal portion 32 projecting outward with respect to the central axis A of the opening 36. In such a secondary side coil 30, when the first terminal portion 31 is the starting end of the secondary side coil 30 and the second terminal portion 32 is the end of the secondary side coil 30, it is input to the first terminal portion 31. The current flows so as to be counterclockwise when the periphery of the opening 37 is viewed from above in FIG. 5, and then flows so as to be clockwise when the periphery of the opening 36 is viewed from above in FIG. Output from the second terminal portion 32.

  The secondary coil 40 has a shape symmetrical with respect to the so-called S-shape (reverse S-shape) when viewed from above in FIG. 5, and two coils arranged in parallel along the X-axis direction. Openings 46 and 47 are provided. The openings 46 and 47 have a larger inner diameter than the openings 26 and 27 of the primary side coil substrate 20 and the primary side coil substrate when the primary side coil substrate 20 and the secondary side coil 40 are overlapped. 20 openings 26 and 27 are provided to communicate with each other. The secondary coil 40 is shaped to circulate around the openings 46 and 47 in different directions in a C shape. A slit 48 extending in the negative direction of the X axis from the opening 46 to the outer periphery of the secondary coil 40 and a slit 49 extending in the negative direction of the Y axis from the opening 47 to the outer periphery of the secondary coil 40 are provided.

  In addition, a first terminal portion 41 that protrudes outward with respect to the central axis A of the opening 46 is provided at one end of the inverted S-shaped secondary coil 40, and the other end of the secondary coil 40 is provided. The part is provided with a second terminal portion 42 that protrudes outward with respect to the central axis B of the opening 47. In such a secondary coil winding 40, when the first terminal portion 41 is the start end of the secondary coil 40 and the second terminal portion 42 is the end of the secondary coil 40, The input current flows so as to be clockwise when the periphery of the opening 46 is viewed from above in FIG. 5, and then counterclockwise when the periphery of the opening 47 is viewed from above in FIG. 5. And output from the second terminal portion 42.

  Further, the secondary coil 41 includes a connection terminal 43 for electrically connecting to the choke coil 161 on the first terminal side 41 side. Moreover, it fixes with the screw | thread 60 so that the 2nd terminal part 32 of the secondary side coil 30 and the 1st terminal part 41 of the secondary side coil 40 may electrically connect. That is, the first terminal portion 32 of the secondary coil 30 and the first terminal portion 41 of the secondary coil 40 fixed by the screw 60 are connected to the secondary coil 142A and the secondary coil 142B shown in FIG. It corresponds to the connection part C. Secondary coils 30 and 40 correspond to secondary coils 142A and 142B shown in FIG. 2, respectively.

  As shown in FIG. 5, the secondary side coils 30 and 40 are fixed to the primary side substrate 20 so as to sandwich the primary side coil substrate 20. At this time, the opening 36 of the secondary side coil 30, the opening 26 of the primary side coil substrate 20, and the opening 46 of the secondary side coil 40 communicate coaxially (that is, the respective openings 26, 36, 46 is on the central axis A extending in the Z-axis direction), and the opening 37 of the secondary coil 30, the opening 27 of the primary coil substrate 20, and the opening 47 of the secondary coil 40, Are connected on the same axis (that is, the centers of the openings 27, 37, 47 are on the central axis B extending in the Z-axis direction), the primary substrate 20 and the secondary coils 30, 40 are Be placed.

  The secondary coils 30 and 40 and the primary coil substrate 20 are fixed by rivets. Specifically, as viewed from above in FIG. 5, after the secondary coil 30, the primary coil substrate 20, and the secondary coil 40 are stacked in this order, the positioning holes 301 of the secondary coil 30, These are fixed by a rivet 501 penetrating the positioning hole 201 of the primary side coil substrate 20 and the positioning hole 401 of the secondary side coil 40. The secondary coil 30 and the primary coil substrate 20 are fixed by a rivet 502 that passes through the positioning hole 302 of the secondary coil 30 and the positioning hole 202 of the primary coil substrate 20. Further, the primary side coil substrate 20 and the secondary side coil 40 are fixed by a rivet 503 that passes through the positioning hole 203 of the primary side coil substrate 20 and the positioning hole 403 of the secondary side coil 40. Thereby, the secondary side coils 30 and 40 and the primary side coil board | substrate 20 are closely_contact | adhered and fixed. At this time, the electrical insulation between the conductor embedded in the primary coil substrate 20 and the secondary coils 30 and 40 is maintained by the insulating members exposed on the front and back surfaces of the primary coil substrate 20. I'm leaning.

  In this way, the primary side coil substrate 20 and the secondary side coils 30 and 40 are integrated by the rivets 501 to 503, so that the screw can be removed by vibration as compared with the case where the primary side coil substrate 20 and the secondary side coil 30 and 40 are integrated by the screw. Can be prevented and durability is increased. Moreover, since the precision at the time of integrating is raised, the variation at the time of manufacture can be made small. Furthermore, when integrating with screws, additional members such as nuts and washers are required, but when using rivets, additional members are not required, so fixing with rivets is more difficult than fixing with screws. It is also superior in terms of workability and cost. Even when the secondary coils 30, 40 and the primary coil substrate 20 are fixed using screws instead of rivets, the secondary side is the same as when these are fixed using rivets. Since the coils 30 and 40 and the primary coil substrate 20 are thermally connected to each other, heat transfer in the Z-axis direction is effectively performed.

  Returning to FIGS. 3 and 4, the first magnetic core 70 and the second magnetic core 80 are attached to the integrated primary coil substrate 20 and secondary coils 30 and 40.

  The first magnetic core 70 is for magnetically connecting the second coil portion 214 and the third coil portion 216 in the primary coil substrate 20 to the secondary coils 30 and 40. That is, the transformer 140 includes a primary side coil conductor including the second coil part 214 and the third coil part 216 in the primary side coil substrate 20 and the secondary side coils 30 and 40. The magnetic core 70 is a magnetic core used in the transformer 140. The first magnetic core 70 is made of a magnetic material such as ferrite. The first magnetic core 70 includes an upper core 71 that is a so-called U-shaped core including two columnar legs 71A and 71B, and a lower core 73 that is a so-called I-shaped core, These are fixed by being connected to each other by a fixing member. That is, the first magnetic core 70 is a so-called UI type magnetic core.

  The leg portion 71A of the upper core 71 of the first magnetic core 70 is formed in the openings 26, 36, 46 of the primary side coil substrate 20 and the secondary side coils 30, 40 along the central axis A shown in FIG. Inserted. Further, the leg portion 71B of the upper core 71 is inserted into the openings 27, 37, 47 of the primary side coil substrate 20 and the secondary side coils 30, 40 along the central axis B shown in FIG. The upper core 71 and the lower core 73 cover a part of the primary coil substrate 20 and the secondary coils 30 and 40, and the first magnetic core 70 extends in the X-axis direction. It is attached to the primary side coil substrate 20 and the secondary side coils 30 and 40.

  At this time, the diameter of the opening 26 of the primary coil substrate 20 is smaller than the diameter of the openings 36 and 46 of the secondary coils 30 and 40, and the outer diameter of the leg portion 71 A of the upper core 71 is the opening 26. It is equivalent to the diameter. Similarly, the diameter of the opening 27 of the primary coil substrate 20 is made smaller than the diameters of the openings 37 and 47 of the secondary coils 30 and 40, and the outer diameter of the leg portion 71 B of the upper core 71 is the opening 27. It is equivalent to the diameter. Therefore, the leg portion 71A and the leg portion 71B can be positioned with high accuracy using the opening 26 and the opening 27, and the movement in the left-right direction when attached is suppressed. In addition, since the opening diameter of the secondary coils 30 and 40 made of the conductor plate is smaller than the opening diameter of the primary coil substrate 20, the leg portions 71A and 71B are inserted when the leg portions 71A and 71B are inserted. 71A, 71B and secondary side coils 30, 40 are held in a separated state. Therefore, there is no need to newly use parts such as a bobbin for maintaining electrical insulation between the coil made of a conductor plate and the legs 71A and 71B of the first magnetic core 70 as in a conventional transformer, The electrical insulation between the primary side coil conductors (second coil part 124 and third coil part 126) and the secondary side coils 30, 40 and the first magnetic core 70 can be achieved.

  As described above, the first magnetic core 70 is fixed to the integrated primary coil substrate 20 and the secondary coils 30 and 40, and is provided inside the primary coil substrate 20. When a current flows through the wiring made of a conductor, a magnetic flux passing through the openings of the second coil portion 214 and the third coil portion 216 is generated, and the direction flowing through the central axis A and the direction flowing through the central axis B are opposite to each other. Thus, a magnetic circuit through which the magnetic flux passes through the first magnetic core 70 is formed. Thereby, the primary side coil conductor 141 and the secondary side coils 142A and 142B are magnetically connected. That is, in this transformer 140, the second coil portion 214 and the third coil portion 216 of the primary side coil substrate 20 function as the primary side coil conductor 141 having four turns. On the other hand, the secondary coils 30 and 40 function as secondary coils 142A and 142B each having one turn.

  The second magnetic core 80 is attached to the first coil portion 212 in the primary coil substrate 20. The first coil portion 212 to which the second magnetic core 80 is attached corresponds to the resonance coil 125, and the second magnetic core 80 is a magnetic core used for the resonance coil 125. The second magnetic core 80 is made of a magnetic material such as ferrite. The second magnetic core 80 includes an upper core 81 that is a so-called E-type core having three legs 81A to 81C, and a lower core 83 that is a so-called I-type core, which are fixed. It is fixed by being connected to each other by members. That is, the second magnetic core 80 is a so-called EI type magnetic core.

  The leg portion 81 </ b> A of the upper core 81 of the second magnetic core 80 is inserted into the opening 23 of the primary side coil substrate 20. Further, the leg portion 81B of the upper core 81 is inserted into the opening 24 provided along the outer peripheral portion of the arc portion 23A of the primary side coil substrate 20. Further, the leg portion 81B of the upper core 81 is arranged along the exposed portion 25 constituting the side surface of the primary coil substrate 20 in the outer peripheral portion of the arc portion 23A. The upper core 81 and the lower core 83 cover a part of the primary coil substrate 20 and the second magnetic core 80 extends in the Y-axis direction. It is attached to. As described above, the second magnetic core 80 is fixed, and a current flows through a conducting wire provided inside the primary side coil substrate 20, whereby the opening of the first coil portion 212 corresponding to the resonance coil 125. Is generated, and a magnetic path through which the magnetic flux passes through the inside of the second magnetic core 80 is formed.

  Next, the shape of the casing 101 that houses the coil component 10 including the above-described primary coil substrate 20, secondary coils 30 and 40, the first magnetic core 70, and the second magnetic core 80 will be described with reference to FIG. Description will be made with reference to FIG. FIG. 7 is a perspective view showing the shape of a portion of the housing 101 that accommodates the coil component 10, and FIG. 8 is a diagram in which the coil component 10 and the primary circuit board 90 are accommodated in the housing 101 of FIG. 9 is a view taken in the direction of arrows VIII-VIII, and FIG. 9 is a view taken in the direction of arrows IX-IX in a state where the coil component 10 is accommodated in the casing 101 of FIG.

  As shown in FIG. 7, the base plate 102 constituting the bottom surface of the casing 101 is provided with irregularities corresponding to the shape of the coil component 10. Specifically, a recess 111 corresponding to the shape of the lower core 73 of the first magnetic core 70 is provided at a position where the lower core 73 of the first magnetic core 70 is disposed, and the coil component 10 is The bottom and side surfaces of the lower core 73 are attached to the base plate 102 so that the recess 111 and the side wall 111A of the recess 111 are in contact with each other. Thus, by providing the side wall 111A of the base plate 102 at a position corresponding to the side surface of the lower core 73, the lower core 73 is fixed to the base plate 102, and the area where the lower core 73 and the base plate 102 are in contact with each other is increased. Since it becomes large and heat can be suitably radiated from the lower core 73 to the base plate 102, the cooling effect by the base plate 102 is enhanced. Similarly, a concave portion 112 corresponding to the shape of the lower core 83 is also provided at a position where the lower core 83 of the second magnetic core 80 is disposed, and the coil component 10 is arranged below the second magnetic core 80. The core 83 is attached to the base plate 102 so that the bottom surface and the side surface of the core 83 are in contact with the recess 112 and the side wall 112A of the recess 112, respectively. As a result, the lower core 83 is fixed to the base plate 102, the area where the lower core 83 and the base plate 102 are in contact with each other is increased, and heat can be suitably radiated from the lower core 83 to the base plate 102. The cooling effect by 102 is enhanced.

  Moreover, the primary side coil board | substrate 20 and the secondary side coils 30 and 40 which comprise said coil component 10 are fixed with respect to the base plate 102 by screwing. Specifically, screw holes 311 and 312 are provided in the secondary coil 30 and screw holes 411 and 412 are provided in the secondary coil 40 in order to fix to the base plate 102. The screws (screws 511A to 511D shown in FIG. 1) inserted into these screw holes are fastened to the screw holes 115A to 115D provided in the base plate 102, whereby the primary coil substrates 20 and 2 are connected. The secondary coils 30 and 40 are fixed to the base plate 102. As a result, the secondary coils 30 and 40 are thermally connected to the base plate 102, respectively.

  In this case, the primary side coil substrate 20 and the secondary side coil substrate 20 and the secondary side coil substrate 20 and the secondary side coils 30 and 40 and the base side plate 102 are maintained so that electrical insulation is maintained. An insulating sheet made of silicone or the like is disposed between the side coils 30 and 40 and the screws as necessary. Further, an insulating sheet may be sandwiched between the first magnetic core 70 and the second magnetic core 80 and the base plate 102 as necessary.

  Further, the base plate 102 is formed with a convex portion 113 that is thermally connected to the heat transfer region 29 on the back surface side of the primary side coil substrate 20 when the coil component 10 is disposed on the base plate 102. As shown in FIG. 3, the heat transfer region 29 of the primary side coil substrate 20 in contact with the convex portion 113 of the base plate 102 has the secondary side coils 30 and 40 and the first magnetic core 70 as viewed from the top of the figure. And a region that does not overlap any of the second magnetic core 80. Here, in order to improve the electrical insulation between the base plate 102 and the primary side coil substrate 20, as shown in FIGS. 7 to 9, the base plate 102 and the primary side coil substrate 20 are made of silicone or the like. An insulating sheet 114 is provided. Further, as shown in FIGS. 8 and 9, the secondary coil 40 on the base plate 102 side and the base plate 102 are also provided with an insulating sheet 116 made of silicone or the like in order to enhance electrical insulation. From the viewpoint of thermal connectivity between the primary side circuit board 90 and the primary side coil board 20, the thickness of the insulating sheet 114 is preferably larger than that of the insulating sheet 116, and is a material having adhesiveness. Is preferred. When the insulating sheet 114 has adhesiveness, the base plate 102 and the primary coil substrate 20 are in close contact with the insulating sheet 114, and the insulating sheet 116 has adhesiveness. In addition, since the base plate 102 and the secondary coil 40 are in close contact with the insulating sheet 116, it further has an effect of absorbing an impact caused by vibration or the like. Further, since the secondary coil 40 on the base plate 102 side is thermally connected to the base plate 102 via the insulating sheet 116, the heat generated in the secondary coil 40 is a heat transfer region of the primary coil substrate 20. The heat is radiated directly to the base plate 102 without going through 29. The heat generated in the secondary coil 30 can be radiated to the base plate 102 via the screws 511A and 511B inserted in the screw holes 311 and 312 of the secondary coil 30. Heat can be transferred from the secondary coil 30 to the primary coil substrate 20 and radiated to the base plate 102 via the heat transfer region 29 of the primary coil substrate 20.

  In addition, in the upper part of the heat transfer area 29, as shown in FIG. 6, a part of the connection portions 211, 213, and 217 of the conductor wiring in the primary coil substrate 20 corresponds to the position corresponding to the heat transfer area 29 (ie, , When viewed from above, it is provided at a position overlapping the heat transfer area 29), and the conductor wiring and the heat transfer area 29 are arranged closer to each other. Further, the heat transfer region 29 is provided between the second coil portion 214 and the third coil portion 216 constituting a part of the transformer 140 and the first coil portion 212 corresponding to the resonance coil 125. That is, the heat transfer region 29 is provided in a region that is closely surrounded by the first coil unit 212, the second coil unit 214, and the third coil unit 216. Specifically, the first coil portion 212 and the opening 23, and the third coil portion 216 and the opening 27 are arranged adjacent to each other in two directions of the heat transfer region 29 (the −X direction and the −Y direction in FIG. 6). The second coil portion 214 and the opening 26 are adjacently arranged in the direction sandwiched between the two directions of the heat transfer region 29. Further, the heat transfer region 29 is formed when the first magnetic core 70 and the second magnetic core 80 are attached to the coil component 10, and the first magnetic core 70 and the second magnetic core. 80 is provided in an adjacent area. In addition, although the ratio of the conductor wiring provided in the position corresponding to the heat transfer area | region 29 among the conductor wiring contained in the primary side coil board | substrate 20 can be made high, the heat dissipation effect by the heat transfer area | region 29 can be heightened. In this embodiment, even if a part of the connection portions 211, 213, and 217 is provided on the upper portion of the heat transfer region 29, the heat dissipation effect through the heat transfer region 29 is enhanced. Further, the heat transfer region 29 may not be a region surrounded by the first coil unit 212, the second coil unit 214, and the third coil unit 216 as in the present embodiment. The part provided in the position corresponding to the heat-transfer area | region 29 may be sufficient.

  Next, the primary circuit board 90 electrically connected to the primary coil board 20 of the coil component 10 and connected to the switching circuit 120 will be described with reference to FIGS. 10 and 11. FIG. 10 is an exploded perspective view illustrating the configuration of the coil component 10 and the primary side circuit board 90, and FIG. 11 is a perspective view of the coil component 10 and the primary side circuit board of FIG. is there. 10 and 11, the first magnetic core 70 and the second magnetic core 80 included in the coil component 10 are not shown.

  The primary circuit board 90 is a four-layer board in which three insulating layers made of a resin such as epoxy resin and four conductor layers sandwiching them are laminated in the thickness direction (Z-axis direction). On the surface, an input smoothing circuit 130 that forms a primary circuit of the switching power supply device and a switching element 124 that constitutes the switching circuit 120 are provided, and the output of the switching circuit 120, the resonance coil 125, and the transformer 140 The first terminal portion 91 and the second terminal portion 92 are electrically connected to each other, and lands for attaching terminals such as the switching elements 124 provided on the front surface by soldering are formed on the back surface thereof. Yes. In the primary circuit board 90, two conductor layers inside the multilayer board excluding the conductor layers on the front surface side and the back surface side are used as wiring layers. In the primary side circuit board 90, the switching element 124 constituting the switching circuit 120 has a switching element terminal portion connected to the primary side circuit board 90 and a switching element body portion thermally connected to the base plate 102. However, the switching element main body may be mounted on the primary circuit board 90 so that the primary circuit board 90 and the main body of the switching element 124 are thermally connected.

  The primary circuit board 90 and the coil component 10 functioning as the transformer 140 and the resonance coil 125 are connected by a connection bus bar 95 and rivets 223A and 223B. Specifically, the connection bus bar 95 includes a bus bar 95A that connects the first terminal portion 21 of the primary side coil substrate 10 and the first terminal portion 91 of the primary side circuit substrate 90, and the primary side coil substrate 10. Bus bar 95 </ b> B for connecting the second terminal portion 22 and the second terminal portion 92 of the primary circuit board 90. Each of the bus bar 95A and the bus bar 95B has a U-shape, and lead terminal portions at both ends are connected to each other by inter-substrate connecting portions. The lead terminal portions at both ends of the bus bar 95A and the bus bar 95B penetrate the primary coil substrate 20 and the primary circuit substrate 90, respectively. In addition, the inter-board connecting portion that connects the lead terminal portions at both ends of the bus bar 95A and the bus bar 95B is provided separately from the primary side coil substrate 20 and the primary side circuit substrate 90. Further, the rivet 223A is fixed through the positioning hole 204 of the primary side coil board 20 and the positioning hole 904 of the primary side circuit board 90, and the rivet 223B is fixed to the positioning hole 205 of the primary side coil board 20 and the primary. The positioning hole 905 of the side circuit board 90 is penetrated and fixed. Thus, the robustness is enhanced by fixing the primary circuit board 90 and the coil component 10 with the rivets 223A and 223B. Further, since the primary circuit board 90 and the coil component 10 are fixed to the housing 101 in an integrated state, the influence of vibration of the DC-DC converter 100 main body can be reduced. Reliability is improved.

  The primary side circuit board 90 has an exposed portion 25 where the arc portion 23A of the primary side coil substrate 20 is exposed on the side surface facing the primary side coil substrate 20 when connected to the coil component 10. A notch portion 93 is provided at the opposing position. This is for inserting the leg portion 81 </ b> C of the upper core 81 of the second magnetic core 80. Specifically, with respect to the space formed by the exposed portion 25 and the notch portion 93 when the primary side circuit board 90 and the primary side coil board 20 are connected by the connecting bus bar 95 and the rivets 223A, B. By inserting the leg portion 81C, the second magnetic core 80 for passing the magnetic flux generated by the first coil portion 212 corresponding to the resonance coil 125 is formed. In this way, by using the space formed by the primary circuit board 90 and the primary coil board 20 as a region for inserting the leg portion 81C of the upper core 81, the primary circuit board 90 and the primary side are used. The coil substrate 20 is downsized.

  The above-described DC-DC converter 100 according to the present embodiment is manufactured by, for example, the following steps. That is, first, the secondary side coils 30 and 40 are fixed to the primary side coil substrate 20 by fixing with rivets. Next, the input smoothing circuit 130, the switching element 124, and the like are attached to the primary side circuit board 90 by soldering, and at that time, the connection bus bar 95 is soldered, thereby the secondary side coils 30, 40 and The integrated primary coil substrate 20 and the primary circuit substrate 90 are connected. Then, the first magnetic core 70 and the second magnetic core 80 are attached to the primary coil substrate 20 integrated with the secondary coils 30 and 40, and these are placed at predetermined positions on the casing 101. The coil component 10 and the primary circuit board 90 are attached to the base plate 102 by mounting and fixing. At this time, the insulating sheets 114 and 116 are sandwiched between the primary side coil substrate 20 of the coil component 10 and the convex portion 113 provided on the base plate 102 and between the secondary side coil 40 and the base plate 102, respectively. The coil component 10 and the primary circuit board 90 are attached to the base plate 102. In addition, since lead-type connection terminals of components (smoothing circuit 130, switching element 124, etc.) attached to the front side penetrate through the back side of the primary side circuit board 90, the back side of the primary side circuit board 90 and The base plate 102 is attached with a predetermined distance away from the surface of the base plate 102. Furthermore, the DC-DC converter 100 is manufactured by fixing components (choke coil 161 and the like) related to the secondary circuit to the casing 101 and electrically connecting to other components previously attached. can do. As described above, the transformer 140 and the primary circuit board can be connected at a time by soldering the connection bus bar 95 to the primary coil board and the primary circuit board 90. The workability is improved as compared with the conventional case where each circuit board is individually attached to the base plate 102.

  As described above, in the coil component 10 constituting the transformer 140 of the DC-DC converter 100 according to the present embodiment, the heat transfer region 29 is provided in the primary side coil substrate 20, and the heat transfer region 29 and the heat dissipation The heat generated in the primary side coil substrate 20 by the thermal connection with the convex portion 113 of the base plate 102 as a member, specifically, the second coil portion 214 and the third coil that form the transformer 140. The heat generated in the portion 216 can be suitably transferred to the base plate 102. That is, since the heat generated in the coil on the primary coil substrate 20 side can be radiated to the base plate 102 without passing through the secondary coils 30 and 40, the heat radiation effect of the primary coil substrate 20 is enhanced. be able to.

  In the DC-DC converter 100 of the present embodiment, the secondary coils 30 and 40 of the coil component 10 are screwed to the base plate 102, respectively. That is, since the secondary side coils 30 and 40 are thermally connected to the base plate 102, the heat generated in the secondary side coils 30 and 40 is suitably radiated from the connecting portion (screwed portion) to the base plate 102. Is done. Further, in the DC-DC converter 100 of the present embodiment, the secondary side coil 40 is thermally connected to the base plate 102 via the insulating sheet 116, and heat generated by the secondary side coil 40 is transmitted to the base plate 102. On the other hand, the heat generated in the secondary coil 30 is transferred from the secondary coil 30 to the primary coil substrate 20 through the heat transfer region 29 of the primary coil substrate 20. Heat can also be radiated to the base plate 102.

  In the coil component 10, the heat transfer region 29 that is thermally connected to the convex portion 113 of the base plate 102 is provided below the conductor wiring (connection portions 211, 213, and 217) in the primary side coil substrate 20. It is done. Therefore, the distance between the conductor wiring in the primary side coil substrate 20 and the heat transfer region 29 can be made closer, and the heat dissipation effect via the heat transfer region 29 is further enhanced. Further, heat conduction to the primary circuit board 90 through the conductor wiring in the primary coil board 20 can be suppressed.

  Further, in the DC-DC converter 100 described above, the primary side circuit board 90 to which the primary side circuit including the switching element 124 is connected is different from the primary side coil board 20 constituting the transformer 140. The thickness of the coil conductor and the conductor wiring in the primary side coil substrate 20 is made thicker than the thickness of the conductor wiring in the primary side circuit board 90 so that the conductor wiring of the primary side circuit board 90 Although the cross-sectional areas of the coil conductor and conductor wiring of the primary side coil substrate 20 are larger than the cross-sectional area, the thickness of the conductor wiring in the primary side coil substrate 20 is set to the thickness of the conductor wiring of the primary side circuit board 90 The thickness, etc. of the conductor can be easily changed according to the properties of the elements connected to the substrate, such as making it thinner.

  In the DC-DC converter 100 described above, the primary side coil conductors (second coil part 214 and third coil part 216) constituting the transformer 140 are provided in the primary side coil substrate 20 of the coil component 10. A first coil portion 212 that constitutes the resonance coil 125 connected in series is provided. As a result, heat generated in the resonance coil 125 can also be effectively radiated to the base plate 102 via the heat transfer region 29.

  In the DC-DC converter 100 described above, the first magnetic core 70 extends in the X-axis direction, and the second magnetic core 80 extends in the Y-axis direction. The length of the second magnetic core 80 extending in the Y-axis direction along the X-axis direction (in the short direction) is the X-axis direction of the first magnetic core 70 extending in the X-axis direction. It is shorter than the length (longitudinal direction) along. As described above, the first magnetic core 70 and the second magnetic core 80 extend in a direction intersecting each other, and the heat transfer region 29 is formed between the first magnetic core 70 and the second magnetic core 80. It is the aspect provided between. As a result, heat generated in both the transformer 140 including the first magnetic core 70 and the resonance coil 125 wound around the second magnetic core 80 is transferred from the primary coil substrate 20 to the base plate 102. Efficient heat dissipation.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to said embodiment, A various change can be made.

  For example, in the above embodiment, the DC-DC converter 100 has been described as an example of the switching power supply device. However, the transformer according to the above embodiment is also applicable to a switching power supply device such as an inverter other than the DC-DC converter 100. Can do. Moreover, although the said embodiment demonstrated in detail about the case where the transformer 140 is a center tap type | mold, it does not need to be a center tap type | mold and is applicable also to another form of transformer.

  Moreover, although the said embodiment demonstrated the structure thermally connected by the secondary side coils 30 and 40 being screwed with respect to the base plate 102 which is a heat radiating member, the secondary side coil 30, 40 may not be thermally connected to the base plate 102. Even when the secondary coils 30 and 40 are not thermally connected to the base plate 102, the primary coil substrate 20 is thermally connected to the base plate 102 in the heat transfer region 29. The heat generated in the primary coil conductor is effectively radiated to the base plate 102.

  Moreover, although the said embodiment demonstrated the case where the primary side coil board | substrate 20 was comprised including the resonance coil 125, the resonance coil 125 does not need to be contained in the primary side coil board | substrate 20. FIG. Even when the resonance coil 125 is not included, the heat generated in the primary coil conductor is transferred to the base plate 102 by being thermally connected to the base plate 102 in the heat transfer region 29 of the primary coil substrate 20. Can effectively dissipate heat. Even when the primary side coil substrate 20 includes the resonance coil 125, the primary side coil conductor and the resonance coil (that is, the first magnetic core 70 and the primary side coil substrate 20). The arrangement of the second magnetic core 80) and the heat transfer area 29 are not limited to the arrangement shown in the above embodiment. Furthermore, the arrangement of the conductor wiring inside the heat transfer area 29 and the primary coil substrate 20 is not limited to the above embodiment, and for example, the conductor wiring is located at a position corresponding to the heat transfer area 29 when viewed from the thickness direction. Even when the is not disposed, the heat generated in the primary coil conductor can be effectively dissipated to the base plate 102.

  Moreover, although the said embodiment demonstrated the structure by which a primary side coil conductor and a resonance coil are embedded in the primary side coil board | substrate 20, a primary side coil conductor and a resonance coil are a primary side coil board | substrate. The structure exposed to the front surface or back surface of 20 may be sufficient. Moreover, although the case where the primary side coil board | substrate 20 and the primary side circuit board 90 are 4 layer boards was demonstrated, the primary side coil board | substrate 20 and the primary side circuit board 90 are not restricted to a 4 layer board | substrate. A multilayer substrate having the number of layers can also be used.

  Further, the shape of the first magnetic core 70 constituting the transformer 140 is not limited to a so-called UI type shape in which only the upper core 71 has legs as shown in the embodiment. For example, both the upper core 71 and the lower core 72 may have a so-called UU shape having leg portions. Also, a so-called EI type core such as the second magnetic core 80 can be used. Similarly, the shape of the second magnetic core 80 is not limited to the shape shown in the above embodiment. Further, the size of the first magnetic core 70 constituting the transformer 140 and the size of the second magnetic core 80 inserted into the resonance coil 125 is not limited to the mode shown in the above embodiment.

  Further, the shape of the coil constituting the transformer 140 is not limited to the above embodiment. In the above embodiment, the configuration in which the primary coil conductor and the secondary coil are wound around the two legs 71A and 71B of the first magnetic core 70 has been described. Only the primary side coil conductor and the secondary side coil can be configured to be wound. Further, a coil wound in the same plane so that the conducting wire draws a spiral may be used as the primary coil conductor or the secondary coil of the transformer 140.

  Moreover, the shape of the base plate 102 which is a heat radiating member is not limited to the said embodiment, A various change can be performed. For example, in the above-described embodiment, the case where the base plate 102 in which the fins on the back surface are air-cooled functions as a heat radiating member, but the base plate 102 that forms the bottom of the casing 101 of the DC-DC converter 100 may not be a heat radiating member. For example, the housing 101 including the base plate 102 and the heat dissipation member may be separate. Furthermore, the shape of the heat transfer region 29 is not limited to the shape of the above embodiment, and can be changed as appropriate according to the shape of the heat dissipation member.

DESCRIPTION OF SYMBOLS 10 ... Coil components, 20 ... Primary side coil board | substrate, 29 ... Heat-transfer area | region, 30, 40 ... Secondary side coil, 70 ... 1st magnetic body core, 80 ... 2nd magnetic body core, 90 ... Primary Side circuit board, 100 ... DC-DC converter, 101 ... housing, 102 ... base plate (heat radiating member), 120 ... switching circuit, 125 ... resonance coil, 140 ... transformer, 212 ... first coil part (resonance coil), 214 ... 2nd coil part (primary side coil conductor), 216 ... 3rd coil part (primary side coil conductor).

Claims (6)

A transformer connected to a primary circuit board to which a switching element is connected,
A substrate connected to the primary circuit board, formed of an insulating member having electrical insulation, a primary coil conductor, and embedded in the substrate and electrically connected to the primary coil conductor. A primary coil substrate having conductor wiring;
Two secondary coils formed by a conductor plate and sandwiching the primary coil substrate from both sides along the thickness direction;
With
The primary coil substrate is a transformer that is thermally connected to a heat radiating member in a heat transfer region that does not overlap the two secondary coils when viewed from the thickness direction.   The transformer according to claim 1, wherein the conductor wiring is embedded in a position corresponding to the heat transfer region of the primary side coil substrate when viewed from the thickness direction.   A switching power supply device comprising the transformer according to claim 1.   The switching power supply according to claim 3, further comprising a base plate on which the transformer is mounted while the heat dissipating member constitutes a part thereof.   5. The switching power supply device according to claim 3, wherein the primary side coil substrate further includes a resonance coil connected in series with the primary side coil conductor. A first magnetic core that magnetically connects the primary coil conductor of the transformer and the secondary coil;
A second magnetic core inserted into the center of the resonant coil to form a magnetic path;
Further comprising
When viewed from the thickness direction, the first magnetic core and the second magnetic core extend in a direction crossing each other, and the heat transfer region includes the first magnetic core and the first magnetic core. 6. The switching power supply device according to claim 5, which is provided between the two magnetic cores.

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