JP2010153724A - Coil substrate structure, and switching power supply device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coil substrate structure and a switching power supply device, capable of enhancing heat dissipation properties and sufficiently securing a mounting region. <P>SOLUTION: The coil substrate structure 100 includes a first coil substrate 110 having a primary transformer coil 41, a second coil substrate 120 superposed on the first coil substrate 110 and having a secondary transformer coil 42, and a transformer core 130 for magnetically connecting the transformer coils 41 and 42. Here, the coil substrates 110 and 120 are stacked in a substrate thickness direction shifting from each other so that the transformer coils 41 and 42 overlap each other. Consequently, the coil substrates 110 and 120 can be increased in heat dissipation area. Further, the transformer coils 41 and 42 are less in width in a transmission direction A than in a direction B crossing the transmission direction A. The stack area of the coil substrates 110 and 120 can be therefore reduced in the transmission direction A. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a coil substrate structure and a switching power supply device including the coil substrate structure.

As a conventional coil substrate structure, a first coil substrate having a primary transformer coil portion, a second coil substrate having a secondary transformer coil portion, and the primary and secondary transformer coils are magnetically coupled. The thing provided with the transformer core for connecting is known (for example, refer patent document 1). The first and second coil substrates in such a coil substrate structure are overlapped with each other so that the primary and secondary transformer coils overlap each other in the substrate thickness direction.
JP 2005-38872 A

  By the way, in recent coil substrate structures, it is required to improve heat dissipation, and what can dissipate heat further from the first and second coil substrates is desired. Further, in the coil substrate structure as described above, further downsizing is required, and in accordance with such a request, mounting parts can be mounted on the mounting area (that is, the first and second coil substrates can be mounted). A large area) is also required.

  Therefore, an object of the present invention is to provide a coil substrate structure and a switching power supply device that can improve heat dissipation and can secure a sufficient mounting area.

  In order to solve the above-described problem, a coil substrate structure according to the present invention includes a first coil substrate having a primary transformer coil portion, and a second coil substrate having a secondary transformer coil portion that is superimposed on the first coil substrate. The primary side and secondary side transformer coil portions are configured to include a conductor pattern extending in a spiral shape when viewed from the substrate thickness direction. The coil substrate is overlapped with each other so that the primary side and secondary side transformer coil portions overlap in the substrate thickness direction, and the primary side and secondary side transformer coil portions are arranged from the substrate thickness direction. When viewed, the width in the predetermined direction is narrower than the width in the intersecting direction of the predetermined direction.

  In the coil substrate structure of the present invention, since the first and second coil substrates are stacked so as to be displaced from each other, their outer surfaces are compared with those in which the first and second coil substrates are stacked so as to coincide with each other. That is, the area of the heat dissipation surface can be increased. Here, the region where the first and second coil substrates overlap each other is a region where the primary side and secondary side transformer coil portions overlap in the substrate thickness direction, and the heat dissipation path of the mounted component becomes longer, so that heat is generated in these regions. It is difficult to mount a large amount of mounting parts. In this regard, in the present invention, when viewed from the substrate thickness direction, the width in the predetermined direction in the primary side and secondary side transformer coil portions is narrowed, and therefore, the region where the first and second coil substrates overlap each other. It will be reduced in a predetermined direction. Therefore, for example, even when the coil substrate structure is miniaturized, it is possible to secure a sufficient mounting area. That is, according to the present invention, it is possible to improve heat dissipation and to secure a sufficient mounting area.

  Moreover, it is a coil board | substrate structure which transmits electric power from the 1st coil board | substrate side to the 2nd coil board | substrate side, Comprising: It is preferable that a predetermined direction is a direction along the transmission direction of electric power. In this case, since the power transmission length in the coil substrate structure is also reduced, the power loss in the coil substrate structure can be reduced.

  In the conductor pattern, the conductor width in a predetermined direction may be narrower than the conductor width in the intersecting direction.

  Moreover, it is preferable to provide the heat radiating member contact | abutted by the other main surface on the opposite side of one main surface in which a mounting component is mounted in a 1st and 2nd coil board | substrate. In this case, the heat of the mounted component mounted on one main surface is thermally conducted to the heat dissipation member via the first and second coil substrates, and is radiated by the heat dissipation member. Therefore, the heat of the mounted component can be further dissipated, and the heat dissipation can be further enhanced.

  At this time, it is preferable that the 1st and 2nd coil board | substrates are piled up so that one with the emitted-heat amount of these may be located in the heat radiating member side. In this case, for example, as shown in FIG. 6A, in one coil substrate 120 located on the heat radiating plate 140 side, the contact area with the heat radiating plate 140 can be made larger than that of the other coil substrate 110. Therefore, the coil substrate 120 having a high calorific value is positioned on the heat radiating plate 140 side and stacked, so that the heat of the coil substrate structure 100 can be effectively radiated.

  Further, as a configuration that preferably exhibits the above-described effects, the first and second coil substrates have a long plate shape and are shifted from each other in the longitudinal direction and overlapped, and the primary side and the secondary side In the transformer coil section, there is a configuration in which the width in the longitudinal direction as the predetermined direction is narrower than the width in the short direction as the intersecting direction when viewed from the substrate thickness direction.

  Further, a transformer core for magnetically connecting the primary side and secondary side transformer coil sections is further provided, and each of the primary side and secondary side transformer coil sections has a through-hole through which the transformer core is inserted. The conductor pattern may be formed in a spiral shape with the through hole as a center.

  Moreover, the switching power supply device according to the present invention comprises the above coil substrate structure. This switching power supply also has the above effect of improving heat dissipation and sufficiently securing a mounting area. Note that examples of the switching power supply device include a DC-DC converter and an AC-DC converter.

  According to the present invention, it is possible to improve heat dissipation and to secure a sufficient mounting area.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted.

  FIG. 1 is a circuit diagram of a switching power supply device according to an embodiment of the present invention. As shown in FIG. 1, the switching power supply device 1 of this embodiment functions as a DC-DC converter, and converts a high-voltage DC input voltage Vin supplied from a high-voltage battery or the like into a low-voltage DC output voltage Vout. Supply to a low-voltage battery or the like.

  The switching power supply device 1 includes a switching circuit 2 and an input smoothing capacitor 3 provided between a primary high voltage line 21 and a primary low voltage line 22, and primary and secondary transformer coils 41 and 42. , A rectifier circuit 5 connected to the secondary transformer coil section 42, and a smoothing circuit 6 connected to the rectifier circuit 5.

  The switching circuit 2 has a full-bridge circuit configuration including switching elements S1 to S4. The switching circuit 2 converts a DC input voltage Vin applied between the input terminals T1 and T2 into an input AC voltage, for example, according to a drive signal supplied from a drive circuit (not shown).

  The input smoothing capacitor 3 smoothes the DC input voltage Vin input from the input terminals T1 and T2. The transformer 4 transforms the input AC voltage generated by the switching circuit 2 and outputs an output AC voltage. The turns ratio of the primary and secondary transformer coils 41 and 42 is appropriately set depending on the transformation ratio. Here, the turns ratio is 3: 1. Therefore, for example, [3V, 1A] power is converted into [1V, 3A] power. The secondary transformer coil part 42 is of a center tap type, and is led to the output terminal T3 via the connection part C and the output line LO.

  The rectifier circuit 5 is a single-layer full-wave rectifier type composed of rectifier diodes 5A and 5B. The cathodes of the rectifier diodes 5A and 5B are connected to the secondary transformer coil section 42, while the anode is connected to the ground line LG and led to the output terminal T4. Thus, the rectifier circuit 5 individually rectifies each half-short wave period of the output AC voltage from the transformer 4 to generate a DC voltage.

  The smoothing circuit 6 includes a choke coil 61 and an output smoothing capacitor 62. The choke coil 61 is inserted into the output line LO. The output smoothing capacitor 62 is connected between the choke coil 61 and the ground line LG in the output line LO. Accordingly, the smoothing circuit 6 smoothes the DC voltage rectified by the rectifying circuit 5 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.

  Next, the structure of the coil substrate constituting the circuit will be described in detail.

  2 is a perspective view showing a main part of the coil substrate structure in the switching power supply device of FIG. 1, and FIG. 3 is an exploded perspective view of the coil substrate structure of FIG. As shown in FIGS. 2 and 3, the coil substrate structure 100 of the present embodiment includes first and second coil substrates 110 and 120 that are stacked so as to be shifted from each other, a transformer core 130, and a heat sink ( Radiating member) 140.

  The coil substrate structure 100 transmits (converts) power along a transmission direction A from the first coil substrate 110 side to the second coil substrate 120 side. That is, the transmission direction (conversion direction) A is a vector direction in which power is transmitted in the coil substrate structure 100.

  The first and second coil substrates 110 and 120 are flat printed boards having the transmission direction A as a longitudinal direction. Each of the first and second coil substrates 110 and 120 includes a resin layer (base material) 7 and a plurality of metal layers 8 (here, two layers of an upper layer and an inner layer) such as a copper layer. (See FIG. 6). The metal layer 8 is a conductor forming layer, and constitutes conductor patterns 44 and 46 described later, and also constitutes a wiring conductor that connects these components to each mounting component 9. An interlayer connection (not shown) is provided between the metal layers 8. Further, necessary portions of the upper surfaces (one main surface) 110a, 120a of the first and second coil substrates 110, 120 are covered with a resist (not shown).

  FIG. 4 is a top view showing the first coil substrate of FIG. As shown in FIG. 4, the first coil substrate 110 has a region extending from the approximate center in the transmission direction A to the downstream side when viewed from the substrate thickness direction (stacking direction) (when viewed from the upper surface 110a side). The primary transformer coil section 41 is provided. A rectangular through hole 43 is formed at a substantially central position of the primary transformer coil portion 41 so that the transformer core 130 is inserted therethrough. The primary transformer coil portion 41 is provided with a conductor pattern 44 extending in a rectangular spiral shape with the through hole 43 as the center.

The conductor pattern 44 is a coil pattern formed of copper or the like on the upper surface 110a side of the first coil substrate 110, for example. The conductor pattern 44, the conductive pattern 44 ₁ extending along the transmission direction A, the conductive pattern 44 ₂ extending along the cross direction B is configured to be continuous.

  In this conductor pattern 44, the conductor width h1a in the transmission direction A is narrower than the conductor width h1b in the direction B (hereinafter, referred to as “intersection direction B”) that intersects (herein, orthogonal) the transmission direction A. As a result, in the primary transformer coil section 41, the width H1A in the transmission direction (predetermined direction) A is narrower than the width H1B in the cross direction B when viewed from the substrate thickness direction. In other words, in the primary-side transformer coil portion 41, the longitudinal width H1A of the first coil substrate 110 is narrower than the lateral width H1B.

In addition, the start end S and the end E of the conductor pattern 44 are appropriately configured from the viewpoint of manufacturing, for example. In the example shown, the top surface 110a as viewed from the substrate thickness direction, end portions of the conductive pattern 44 ₁ located upper side in the figure is a starting end S, the conductive pattern 44 ₁ positioned shown below the through-holes 43 The end portion is the end E. Therefore, the number of conductive patterns 44 ₂ ″ extending in the downstream region in the transmission direction A is larger than the number of conductive patterns 44 ₂ ′ extending in the upstream region in the transmission direction A. conductive 'conductor width of h1a' pattern 44 _{2 ''} is narrower than 'conductor width h1a of' the conductor pattern 44 _2.

  The starting end S is connected to the switching elements S 1 and S 2 of the switching circuit 2 by a conductor formed of the inner metal layer 8 in the first coil substrate 110. Further, the terminal E is connected to the switching elements S3 and S4 of the switching circuit 2 by a conductor formed of the inner metal layer 8 in the first coil substrate 110.

  FIG. 5 is a top view showing the second coil substrate of FIG. As shown in FIG. 5, the second coil substrate 120 is provided with the secondary transformer coil portion 42 in a region extending from the upstream side to the center in the transmission direction A when viewed from the substrate thickness direction. ing. A rectangular through hole 45 is formed at a substantially central position of the secondary transformer coil portion 42 so that the transformer core 130 is inserted therethrough. The secondary transformer coil section 42 is provided with a conductor pattern 46 extending in a rectangular spiral shape with the through hole 45 as the center.

The conductor pattern 46 is a coil pattern formed of copper or the like on the upper surface 120a side of the second coil substrate 120. The conductor pattern 46, the conductive pattern 46 ₁ extending along the transmission direction A, the conductive pattern 46 ₂ extending along the cross direction B is configured to be continuous.

  In the conductor pattern 46, the conductor width h <b> 2 a in the transmission direction A is narrower than the conductor width h <b> 2 b in the intersecting direction B, like the primary transformer coil portion 41. Thereby, also in the secondary side transformer coil part 42, the width H2A of the transmission direction A is narrower than the width H2B of the crossing direction B when seen from the substrate thickness direction. In other words, also in the secondary transformer coil section 42, the width H2A in the longitudinal direction of the second coil substrate 130 is narrower than the width H2B in the short direction.

  2 and 3, the first and second coil substrates 110 and 120 described above are arranged so that only the primary and secondary transformer coil portions 41 and 42 overlap in the substrate thickness direction (that is, the primary coil substrate 110 and 120). The side and secondary transformer coils 41 and 42 are stacked as a stacking region), and the through holes 43 and 45 are shifted from each other in the transmission direction A so as to communicate with each other. Here, the 2nd coil board | substrate 120 is laminated | stacked so that it may be located in the heat sink 140 side (lower side).

  In each of the first and second coil substrates 110 and 120, a mounting component 9 such as a semiconductor component is mounted on each of the upper surfaces 110a and 120a with a region other than the stacked region as a mounting region R. Specifically, as shown in FIG. 2, the switching elements S1 to S4 are mounted and mounted on the mounting region R of the first coil substrate 110, and the rectification is performed on the mounting region R of the second coil substrate 120. Diodes 5A and 5B are mounted and mounted.

  Examples of the switching element include a field effect transistor (MOS-FET) and an IGBT (Insulated Gate Bipolar Transistor).

  Further, the second coil substrate 120 has at least a core 122 made of a magnetic material such as ferrite, for example, corresponding to the choke coil 61. The core 122 is inserted into a rectangular through hole 123 (see FIG. 5) formed at the downstream end portion in the transmission direction A in the second coil substrate 120.

  The transformer core 130 is for magnetically connecting the primary and secondary transformer coils 41 and 42 to each other, and constitutes the transformer 4. The transformer core 130 is made of a magnetic material such as ferrite, for example. Further, as shown in FIG. 3, the transformer core 130 includes an upper core 131 that is a so-called U-type core and a lower core 132 that is a so-called I-type core, which are connected to each other by a fixing member (not shown). It is fixed.

  The transformer core 130 has an upper core 131 inserted in the through holes 43 and 45. The transformer core 130 is attached to the first and second coil substrates 110 and 120 so that the cores 131 and 132 cover a part of the primary and secondary transformer coil portions 41 and 42. .

  The heat radiating plate 140 radiates the heat of the first and second coil substrates 110 and 120 and radiates the heat of the mounted component 9 through the first and second coil substrates 110 and 120. is there. The heat radiating plate 140 is made of aluminum, for example, and has a thermal conductivity higher than that of the first and second coil substrates 110 and 120.

  Further, the heat radiating plate 140 includes a heat radiating surface 141 that contacts the lower surface (other main surface) 110b of the first coil substrate 110, and a heat radiating surface 142 that contacts the lower surface (other main surface) 120b of the second coil substrate 120. ,have. These heat radiating surfaces 141 and 142 are configured to be continuous with a stepped portion 143 having a height equal to the thickness of the second coil substrate 120. In addition, the heat radiating surface 142 is formed with a concave portion 144 that is recessed along the shape of the lower core 132 to lock the lower core 132.

  And in the heat sink 140, the 1st and 2nd coil boards 110 and 120 are each mounted in each heat sinking surface 141,142 so that the lower core 132 may be arrange | positioned in the recessed part 144. As shown in FIG. Thereby, as shown in FIG. 6A, the lower surfaces 110 b and 120 b of the first and second coil substrates 110 and 120 are brought into contact with the heat radiating plate 140.

  Specifically, in addition to the regions corresponding to the mounting region R on the lower surfaces 110b and 120b of the first and second coil substrates 110 and 120 being in contact with the heat radiating surfaces 141 and 142, the second coil substrate 120 A region that is not covered with the transformer core 130 in the stacked region of the lower surface 120 b is in contact with the heat radiating surface 142. As a result, part of the secondary transformer coil portion 42 is also brought into thermal contact with the heat radiating plate 140, and the heat radiating surface area (contact area with the heat radiating plate 140) can be further increased. Here, in the second coil substrate 120, the side surface 120 c on the upstream side in the transmission direction A is close to or in contact with the stepped portion 143.

  In the switching power supply device 1 configured as described above, the DC input voltage Vin supplied from the input terminals T <b> 1 and T <b> 2 is switched to generate an input AC voltage, which is supplied to the primary-side transformer coil unit 41 of the transformer 4. Is done. Then, the generated input AC voltage is transformed and output from the secondary transformer coil section 42 as an output AC voltage. The output AC voltage is rectified by the rectifier circuit 5 and smoothed by the smoothing circuit 6, and is output as the DC output voltage Vout from the output terminals T3 and T4.

  As described above, according to the present embodiment, the first and second coil substrates 110 and 120 are stacked while being displaced from each other. Therefore, the first and second coil substrates 110 and 120 are compared with the conventional coil substrate structure (see FIG. 6B: hereinafter referred to as “conventional substrate structure”) 200 in which the first and second coil substrates 110 and 120 are overlapped with each other. The area of the heat dissipation surface (outer surface) of the second coil substrates 110 and 120 can be increased. As a result, the heat dissipation of the coil substrate structure 100 can be improved.

  Further, since the first and second coil substrates 110 and 120 do not overlap in the mounting region R, the following effects can be obtained compared to the conventional substrate structure 200. That is, when heat of the mounting component 9 is propagated through the first and second coil substrates 110 and 120 to the heat radiating plate 140, the heat dissipation path of the mounting component 9 is shortened, so the first and second coil substrates 110, The thermal resistance due to 120 can be reduced, and the heat dissipation can be further enhanced. Further, since the first and second coil substrates 110 and 120 can be formed thin, the cost can be reduced.

  Here, the laminated region is a region where the primary-side and secondary-side transformer coil portions 41 and 42 overlap each other in the substrate thickness direction, and the heat dissipation path of the mounted component 9 becomes longer. It is usually considered difficult to install in In this regard, in the primary and secondary transformer coils 41 and 42 of the present embodiment, as described above, the widths H1A and H2A in the transmission direction A are narrowed when viewed from the substrate thickness direction. Therefore, in the present embodiment, the stacked region is reduced in the transmission direction A. As a result, it is possible to sufficiently secure the mounting region R while reducing the size of the coil substrate structure 100 in the transmission direction A. In other words, the mounting region R can be sufficiently secured without requiring an increase in size of the first and second coil substrates 110 and 120.

  Therefore, since this embodiment can sufficiently secure both the heat radiation area and the mounting area R, it can be said that the present embodiment is small in size and excellent in heat radiation performance and can be reduced in cost. Since the number of the resin layers 7 between the metal layers 8 increases as the number of the metal layers 8 included in the first and second coil substrates 110 and 120 increases, from the mounting component 9 to the heat sink 140. Since the thermal resistance of the first and second coil substrates 110 and 120, which is the thermal resistance, increases, the above effect of reducing the thermal resistance becomes significant in the coil substrate including many metal layers.

  Furthermore, in the coil substrate structure 100 of the present embodiment, as described above, since the size is reduced in the transmission direction A, the power transmission length of the coil substrate structure 100 is also reduced, so that the power loss of the coil substrate structure 100 is reduced. It can also be reduced.

  In the present embodiment, as described above, the heat radiating plate 140 is in direct contact with both the lower surfaces 110b and 120b of the first and second coil substrates 110 and 120. Therefore, the heat of the mounting component 9 can be radiated by conducting heat to the heat radiating plate 140 via the first and second coil substrates 110 and 120, and the heat of the mounting component 9 can be further dissipated. Become.

  By the way, in this embodiment, compared with the electric current value which flows into the primary side transformer coil part 41, since the electric current value which flows into the secondary side transformer coil part 42 is enlarged, the 1st which has the primary side transformer coil part 41 is included. Compared with the coil substrate 110, the amount of heat generated by the second coil substrate 120 having the secondary transformer coil portion 42 is higher.

  In this regard, in the present embodiment, the first and second coil substrates 110 and 120 are stacked on each other so that the second coil substrate 120 is located on the heat dissipation plate 140 side, and the stacked region of the lower surface 120b of the second coil substrate 120 is. A part is also in contact with the heat sink 140. Therefore, the contact area between the heat radiating plate 140 and the second coil substrate 120 can be made larger than the contact area between the heat radiating plate 140 and the first coil substrate 110, and the second coil substrate 120 can be further radiated to form a coil substrate structure. 100 heat can be effectively dissipated.

  In the present embodiment, as described above, since the side surface 120c of the second coil substrate 120 is close to or in contact with the stepped portion 143, a heat dissipation path from the side surface 120c can be secured, and heat dissipation can be further improved. Become. Incidentally, in this embodiment, since the transformer 4 is formed by stacking the primary side and secondary side transformer coil portions 41 and 42 in the vertical direction, this embodiment has a small leakage inductance.

  Incidentally, in the present embodiment, the number of turns of the primary transformer coil section 41 is 3 and the number of turns of the secondary transformer coil section 42 is 1, but the number of turns is not limited. Further, the conductor patterns 44 and 46 may be formed in a plurality of layers by providing the conductor patterns 44 and 46 not only on the upper metal layer 8 but also on the inner metal layer 8. For example, the number of turns of the first coil substrate 110 can be reduced to 6 by forming a conductor pattern having 3 turns on the inner metal layer 8 on the first coil substrate 110 side. In the inner metal layer 8 as well, the width of the transmission direction (predetermined direction) A of the transformer coil portions 41 and 42 is made narrower than the width of the intersecting direction B, thereby increasing the area of the transformer coil portions 41 and 42. The number of turns can be increased without any problems.

  Further, in the present embodiment, a high-voltage DC voltage is input from a terminal electrode (not shown) located on the opposite end side of the first coil substrate 110 from the stacked region, and the second coil substrate is opposite to the stacked region. A low-voltage DC voltage is output from a terminal electrode (not shown) located on the end side. Therefore, here, the rectifier diode 5A of the second coil substrate 120 from the region where the switching elements S1 to S4 of the first coil substrate 110 are provided via the primary side and secondary side transformer coil portions 41, 42. The direction to the area where 5B is provided is the transmission direction A.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, in the above-described embodiment, the through holes 43 and 45 are formed at substantially the center positions in the primary side and secondary side transformer coil portions 41 and 42, respectively. The through-holes 43 and 45 may be formed at various positions in the side transformer coil portions 41 and 42, respectively.

For example, as shown in FIG. 7, through holes 43 </ b> A and 45 </ b> A located on the upstream side in the transmission direction A may be formed in the primary and secondary transformer coil portions 41 and 42. In the primary-side and secondary-side transformer coil portions 41 and 42 of the coil substrate structure 100A, the region on the downstream side in the transmission direction A of the through holes 43A and 45A is expanded, so that the number of the conductive patterns 44 ₂ ″ is the number of the conductive patterns 44. Even if the number is larger than ₂ ′, the conductor width h1a ″ and the conductor width h1a ′ can be made comparable. Therefore, it is possible to suppress an increase in the amount of heat generated by the conductive pattern 44 ₂ ″ because the conductor width h1a ″ is narrow.

  In the transformer core 130 of the above embodiment, a U-type core is used as the upper core 131 and an I-type core is used as the lower core 132. However, an E-type core may be used as the upper core, and an I-type may be used as the lower core. A core or an E-type core may be used. Moreover, in the said embodiment, although the widths H1A and H2A of the transmission direction A in the transformer coil parts 41 and 42 were narrowed, the direction of this width is not limited to the transmission direction A, and may be various directions. Good.

  Note that the switching power supply device 1 is not limited to the DC-DC converter, and may be an AC-DC converter or the like. Moreover, in the said embodiment, although the said circuit of the switching power supply device 1 is made into the center tap type anode common, it is good also as a center tap type cathode common, for example. Furthermore, in the above embodiment, the height of the stepped portion 143 is set equal to the thickness of the second coil substrate 120, but may be thicker (higher) than the thickness of the second coil substrate 120.

  Moreover, in the said embodiment, although the multilayer substrate was used as the 1st and 2nd coil substrates 110 and 120, you may use a single layer substrate. Furthermore, the widths of the first and second coil substrates 110 and 120 may be different from each other.

  In the above embodiment, the first and second coil substrates 110 and 120 stacked (stacked) on each other include those in contact with each other and those in contact with each other. This includes those arranged to overlap.

  In the above embodiment, the power semiconductor elements such as the switching elements S1 to S4 and the rectifier diodes 5A and 5B are surface-mounted on the upper surfaces 110a and 120a of the first and second coil substrates 110 and 120 as the mounting component 9. Along with this power semiconductor element, a surface-mounted passive element such as a coil or a capacitor may be surface-mounted. In this case, the lower surfaces 120 a and 120 b corresponding to the portions where the power semiconductor elements are mounted in the first and second coil substrates 110 and 120 may be at least in contact with the heat radiating plate 140.

It is a circuit diagram of the switching power supply concerning one embodiment of the present invention. It is a perspective view which shows the principal part of the coil board | substrate structure in the switching power supply device of FIG. FIG. 3 is an exploded perspective view of the coil substrate structure of FIG. 2. It is a top view which shows the 1st coil board | substrate of FIG. It is a top view which shows the 2nd coil board | substrate of FIG. (A) is a schematic diagram of the cross section along the VI-VI line of FIG. 2, (b) is a schematic diagram corresponding to FIG. 6 (a) in the conventional coil substrate structure. It is a disassembled perspective view of the coil board | substrate structure in the switching power supply device which concerns on the modification of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Switching power supply device, 9 ... Mounting component, 41 ... Primary side transformer coil part, 42 ... Secondary side transformer coil part, 44, 46 ... Conductor pattern, 100, 100A ... Coil board structure, 110 ... 1st coil board 110a ... Upper surface (one main surface), 110b ... Lower surface (other main surface), 120 ... Second coil substrate, 120a ... Upper surface (one main surface), 120b ... Lower surface (other main surface), 130 ... Transformer core, 140 ... heat radiating plate (heat radiating member), A ... transmission direction (predetermined direction), B ... crossing direction, H1A, H1B, H2A, H2B ... width, h1a, h1b, h2a, h2b ... conductor width.

Claims (8)

A first coil substrate having a primary transformer coil section;
A coil substrate structure comprising: a second coil substrate having a secondary-side transformer coil portion, overlaid on the first coil substrate,
The primary side and secondary side transformer coil parts are configured to include a conductor pattern extending in a spiral shape when viewed from the substrate thickness direction,
The first and second coil substrates are overlapped with each other so that the primary and secondary transformer coil portions overlap in the substrate thickness direction,
The coil substrate structure characterized in that, in the primary side and secondary side transformer coil portions, the width in the predetermined direction is narrower than the width in the intersecting direction of the predetermined direction when viewed from the substrate thickness direction. A coil substrate structure for transmitting power from the first coil substrate side to the second coil substrate side;
The coil substrate structure according to claim 1, wherein the predetermined direction is a direction along a transmission direction of the electric power.   3. The coil substrate structure according to claim 1, wherein a conductor width in the predetermined direction is narrower than a conductor width in the intersecting direction in the conductor pattern.   4. The heat dissipation member in contact with the other main surface opposite to the one main surface on which the mounting component is mounted on the first and second coil substrates is provided. The coil substrate structure described.   5. The coil substrate structure according to claim 4, wherein the first and second coil substrates are overlapped so that one of them, which generates a large amount of heat, is located on the heat radiating member side. The first and second coil substrates have a long plate shape and are stacked with being shifted from each other in the longitudinal direction.
In the primary-side and secondary-side transformer coil sections, when viewed from the substrate thickness direction, the width in the longitudinal direction as the predetermined direction is narrower than the width in the short direction as the intersecting direction. The coil substrate structure according to any one of claims 1 to 5. A transformer core for magnetically connecting the primary and secondary transformer coils;
Each of the primary side and secondary side transformer coil portions is formed with a through hole through which the transformer core is inserted,
The coil substrate structure according to any one of claims 1 to 6, wherein the conductor pattern extends in a spiral shape with the through hole as a center.   A switching power supply comprising the coil substrate structure according to any one of claims 1 to 7.

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