JP2014175631A - Magnetic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic device allowing a circuit board provided with a coil pattern to easily dissipate heat without an increase in size.SOLUTION: A magnetic device 1 includes a core 2a composed of a magnetic material, a circuit board 3 composed of an insulator and through which protrusions 2m, 2L and 2r of the core 2a penetrate, and a conductor provided in the circuit board 3. The conductor includes coil patterns 4a, 4b, 4c, 4d and 4e wound around the protrusions 2m, 2L and 2r, heat dissipation patterns 5a, 5b, 5c, 5d and 5e, and others. A heat sink is provided on a rear side of the circuit board 3. The conductor provided in a rear surface layer L3 of the circuit board 3 is greater in area than the conductor provided in a top surface layer L1 of the circuit board 3.

Description

  The present invention relates to a magnetic device such as a choke coil or a transformer, which includes a core made of a magnetic material and a substrate on which a coil pattern is formed.

  For example, there is a switching power supply device such as a DC-DC converter (DC-DC converter) that converts a high-voltage direct current into a alternating current after switching to a low-voltage direct current. The switching power supply device uses a magnetic device such as a choke coil or a transformer.

  For example, Patent Documents 1 to 6 disclose a magnetic device including a coil pattern in which a coil winding is formed on a substrate.

  In patent documents 1-5, the core which consists of a magnetic body has penetrated the board | substrate. The substrate is made of an insulator and has a plurality of layers. A coil pattern is formed on each layer so as to be wound around the core. Coil patterns of different layers are connected by through holes or the like. The coil pattern and the through hole are made of a conductor such as copper.

  In Patent Document 6, the substrate is composed of a pair of insulating layers and a magnetic layer sandwiched between the insulating layers. A coil pattern made of a conductor is formed on the magnetic layer. The coil pattern is wound a plurality of times in the plate surface direction and the thickness direction of the substrate.

  When a current flows through the coil pattern, heat is generated from the coil pattern, and the temperature of the substrate rises. As a heat dissipation measure for the substrate, in Patent Document 1, the coil pattern is spread over almost the entire area of each layer of the substrate. Moreover, in patent document 3, the width | variety of a part of coil pattern of each layer of a board | substrate is expanded, and the thermal radiation pattern part is provided. In Patent Document 6, a heat-dissipating conductor layer is provided on the inner side of the coil pattern, the heat-transmitting penetrating conductor passing through the magnetic layer and the lower insulating layer, and connected to the heat-transmitting penetrating conductor on the lower surface of the substrate. Is provided.

JP 2008-205350 A Japanese Unexamined Patent Publication No. 7-38262 Japanese Patent Laid-Open No. 7-86755 Reissue WO2010 / 026690 JP-A-8-69935 JP 2008-177516 A

  For example, in a magnetic device used in a DC-DC converter through which a large current flows, a large current flows through the coil pattern and the amount of heat generated increases. If the temperature of the substrate increases due to this heat generation, the characteristics of the magnetic device may vary or the performance may deteriorate. In addition, when an electronic component such as another IC chip is mounted on the same substrate, there is a risk of malfunction or destruction of the electronic component.

  If the width is increased over the entire length of the coil pattern to reduce the DC resistance, the amount of heat generated from the coil pattern can be reduced. However, this increases the size of the magnetic device, which is against the demand for miniaturization.

  The subject of this invention is providing the magnetic device which can make it easy to thermally radiate the board | substrate with which the coil pattern was provided, without enlarging.

  A magnetic device according to the present invention includes a core made of a magnetic material, a substrate made of an insulator, through which the core penetrates, and a conductor provided on the substrate including a coil pattern wound around the core. . A radiator is provided on the back side of the substrate, and the area of the conductor provided on the back layer of the substrate is larger than the area of the conductor provided on the surface layer of the substrate.

  Thereby, since the heat of the board | substrate with which the coil pattern was provided becomes easy to be transmitted to a heat radiator from the conductor with a large area provided in the back surface layer, it can make it easy to radiate a board | substrate. As a result, the width of the coil pattern does not have to be increased over the entire length of the coil pattern so that the amount of generated heat is reduced, and the magnetic device can be prevented from being enlarged.

  According to the present invention, in the above magnetic device, the conductor provided on the front surface layer and the back surface layer of the substrate may include a coil pattern and a heat radiation pattern formed integrally or separately from the coil pattern. Good.

  Moreover, in this invention, you may fix a board | substrate and a heat sink with a screw in the area | region where the conductor in the surface layer of a board | substrate does not exist in the said magnetic device.

  Furthermore, in the present invention, in the magnetic device, an insulating sheet having heat conductivity may be sandwiched between the substrate and the radiator.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the magnetic device which can make it easy to thermally radiate the board | substrate with which the coil pattern was provided, without enlarging.

It is a block diagram of a switching power supply device. 1 is an exploded perspective view of a magnetic device according to a first embodiment of the present invention. It is a top view of each layer of the board | substrate of FIG. It is sectional drawing of the magnetic device of FIG. It is a top view of each layer of a substrate of a magnetic device by a 2nd embodiment of the present invention. It is sectional drawing of the magnetic device of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

  FIG. 1 is a configuration diagram of the switching power supply apparatus 100. The switching power supply device 100 is a DC-DC converter for an electric vehicle (or a hybrid car), which switches a high-voltage direct current to an alternating current and then converts it to a low-voltage direct current. This will be described in detail below.

  A high voltage battery 50 is connected to the input terminals T <b> 1 and T <b> 2 of the switching power supply device 100. The voltage of the high voltage battery 50 is, for example, DC 220V to DC 400V. The DC voltage Vi of the high-voltage battery 50 input to the input terminals T1 and T2 is applied to the switching circuit 52 after noise is removed by the filter circuit 51.

  The switching circuit 52 is formed of a known circuit having, for example, an FET (Field Effect Transistor). In the switching circuit 52, the FET is turned on / off based on a PWM (Pulse Width Modulation) signal from the PWM drive unit 58, and a switching operation is performed on the DC voltage. As a result, the DC voltage is converted into a high-frequency pulse voltage.

  The pulse voltage is given to the rectifier circuit 54 via the transformer 53. The rectifier circuit 54 rectifies the pulse voltage by a pair of diodes D1 and D2. The voltage rectified by the rectifier circuit 54 is input to the smoothing circuit 55. The smoothing circuit 55 smoothes the rectified voltage by the filtering action of the choke coil L and the capacitor C, and outputs the smoothed voltage to the output terminals T3 and T4 as a low DC voltage. With this DC voltage, the low voltage battery 60 connected to the output terminals T3 and T4 is charged to, for example, DC12V. The DC voltage of the low-voltage battery 60 is supplied to various on-vehicle electrical components (not shown).

  The output voltage Vo of the smoothing circuit 55 is detected by the output voltage detection circuit 59 and then output to the PWM drive unit 58. The PWM drive unit 58 calculates the duty ratio of the PWM signal based on the output voltage Vo, generates a PWM signal corresponding to the duty ratio, and outputs the PWM signal to the gate of the FET of the switching circuit 52. As a result, feedback control is performed to keep the output voltage constant.

  The control unit 57 controls the operation of the PWM drive unit 58. A power source 56 is connected to the output side of the filter circuit 51. The power supply 56 steps down the voltage of the high voltage battery 50 and supplies a power supply voltage (for example, DC 12 V) to the control unit 57.

  In the switching power supply device 100 described above, magnetic devices 1 and 1 ′ described later are used as the choke coil L of the smoothing circuit 55. A large current of, for example, DC 150A flows through the choke coil L. At both ends of the choke coil L, terminals 6i and 6o for power input / output are provided.

  Next, the structure of the magnetic device 1 according to the first embodiment will be described with reference to FIGS.

  FIG. 2 is an exploded perspective view of the magnetic device 1. FIG. 3 is a plan view of each layer of the substrate 3 of the magnetic device 1. 4A and 4B are cross-sectional views of the magnetic device 1, wherein FIG. 4A shows a cross section taken along line XX in FIG. 3, and FIG. 4B shows a cross section taken along line YY in FIG.

  As shown in FIG. 2, the cores 2 a and 2 b are configured by a pair of an E-shaped upper core 2 a and an I-shaped lower core 2 b. The cores 2a and 2b are made of a magnetic material such as ferrite or amorphous metal.

  The upper core 2a has three convex portions 2m, 2L, and 2r so as to protrude downward. The left and right protrusions 2L and 2r have a larger amount of protrusion than the center protrusion 2m.

  As shown in FIG. 4A, the lower ends of the left and right convex portions 2L, 2r of the upper core 2a are brought into close contact with the upper surface of the lower core 2b, and the cores 2a, 2b are combined. In this state, a gap of a predetermined size is provided on the upper surface of the convex portion 2m of the upper core 2a and the upper surface of the lower core 2b in order to improve the DC superimposition characteristics. Thereby, even when a large current is passed through the magnetic device 1, a predetermined inductance can be realized (the same applies to a magnetic device 1 'described later). The cores 2a and 2b are fixed by fixing means such as screws and metal fittings (not shown).

  The lower core 2 b is fitted into a recess 10 k (FIG. 2) provided on the upper side of the heat sink 10. A fin 10 f is provided on the lower side of the heat sink 10. The heat sink 10 is made of metal and is an example of the “heat radiator” of the present invention.

  The board | substrate 3 is comprised from the thick copper foil board | substrate with which the pattern was formed in each layer of the thin-plate-shaped base material which consists of an insulator with thick copper foil (conductor). In the present embodiment, other electronic components and circuits are not provided on the substrate 3, but when the magnetic device 1 is actually used in the switching power supply device 100 of FIG. 1, the magnetic device 1 and the switching power supply device are provided on the same substrate. 100 other electronic components and circuits are provided (the same applies to a magnetic device 1 ′ described later).

  A surface layer L1 as shown in FIG. 3A is provided on the surface of the substrate 3 (upper surface in FIGS. 2 and 4). A back surface layer L3 as shown in FIG. 3C is provided on the back surface of the substrate 3 (the bottom surface in FIGS. 2 and 4). As shown in FIG. 4, an intermediate layer L2 as shown in FIG. 3B is provided between the front surface layer L1 and the back surface layer L3. That is, the substrate 3 has three layers L1, L2, and L3 that can form a circuit.

  The substrate 3 is provided with a plurality of through holes 3m, 3L, 3r, and 3a. Among them, as shown in FIGS. 2 to 4, the convex portions 2m, 2L, and 2r of the core 2a are inserted into the large-diameter through holes 3m, 3L, and 3r, respectively. That is, the convex portions 2m, 2L, and 2r of the core 2a penetrate the substrate 3.

  As shown in FIG. 2, each screw 11 is inserted into the plurality of small diameter through holes 3a. The back surface (back surface layer L3) of the substrate 3 is opposed to the upper surface of the heat sink 10 (the surface opposite to the fin 10f). Then, the screws 11 are passed through the through holes 3 a from the surface (surface layer L 1) side of the substrate 3 and screwed into the screw holes 10 a of the heat sink 10. Thereby, as shown in FIG. 4, the heat sink 10 is fixed to the back surface side of the board | substrate 3 in the proximity | contact state.

  An insulating sheet 12 having heat conductivity is sandwiched between the substrate 3 and the heat sink 10. Since the insulating sheet 12 has flexibility, it is in close contact with the substrate 3 and the heat sink 10 without a gap.

  As shown in FIG. 3, the substrate 3 is provided with conductors such as through holes 8a, 8d, 9a to 9d, pads 8b and 8c, terminals 6i and 6o, patterns 4a to 4f, 5a to 5e, and pins 7a to 7f. It has been.

  Through holes 8a, 8d, and 9a to 9d connect patterns 4a to 4f and 5c to 5e in different layers L1, L2, and L3. Specifically, the plurality of through holes 8a connect the patterns 4a and 4b of the upper layer L1 to the other layers L2 and L3. Each through hole 8d connects the upper layer L1 and the other layers L2, L3, connects the patterns 4a, 4b of the upper layer L1 and the pattern 5e of the lower layer L3, and connects the patterns 4c, 4d of the intermediate layer L2 and the lower layer L3. The patterns 5c and 5d are connected. The through holes 9a and 9d connect the patterns 4a and 4b of the upper layer L1 and the patterns 4c and 4d of the intermediate layer L2. The through holes 9b and 9c connect the patterns 4c and 4d of the intermediate layer L2 and the pattern 4e of the lower layer L3.

  Of the pair of large-diameter through holes 8a, one through hole 8a has a power input terminal 6i embedded therein. A power output terminal 6o is embedded in the other through hole 8a. Terminals 6i and 6o are made of copper pins. A pad 8b made of copper foil is provided around the terminals 6i and 6o of the front surface layer L1 and the back surface layer L3. Copper plating is applied to the surfaces of the terminals 6i and 6o and the pad 8b. The lower ends of the terminals 6i and 6o are in contact with the insulating sheet 12 (not shown).

  Heat radiation pins 7a to 7f are embedded in the plurality of large-diameter through holes 8d, respectively. The heat radiation pins 7a to 7f are made of copper pins. A pad 8c made of copper foil is provided around the heat radiation pins 7a to 7f of the front surface layer L1 and the back surface layer L3. Copper plating is applied to the surfaces of the heat radiation pins 7a to 7f and the pad 8c. The lower ends of the heat radiation pins 7a to 7f are in contact with the insulating sheet 12 (see FIG. 4A).

  Coil patterns 4a to 4e and heat radiation patterns 5a to 5e are provided on the layers L1, L2, and L3 of the substrate 3, respectively. Each pattern 4a-4e, 5a-5e consists of copper foil. The surface of each pattern 4a-4e, 5a-5e of the surface layer L1 is subjected to insulation processing. The width, thickness, and cross-sectional area of the coil patterns 4a to 4e can suppress the amount of heat generated from the coil patterns 4a to 4e to some extent even when a predetermined large current (for example, DC150A) flows, and the coil patterns 4a to 4e. It is set to be able to dissipate heat from the surface.

  As shown in FIG. 3A, in the surface layer L1, the coil pattern 4a is wound once in the four directions around the convex portion 2L. The coil pattern 4b is wound once in four directions around the convex portion 2r.

  As shown in FIG. 3B, in the intermediate layer L2, the coil pattern 4c is wound once in the four directions around the convex portion 2L. The coil pattern 4d is wound once in the four directions around the convex portion 2r.

  As shown in FIG. 3C, in the back layer L3, the coil pattern 4e is wound once in the four directions around the convex portion 2L, and then wound once in the three directions around the convex portion 2m. Further, it is wound once in four directions around the convex portion 2r.

  One end of the coil pattern 4a and one end of the coil pattern 4c are connected by a through hole 9a. The other end of the coil pattern 4c and one end of the coil pattern 4e are connected by a through hole 9c. The other end of the coil pattern 4e and one end of the coil pattern 4d are connected by a through hole 9b. The other end of the coil pattern 4d and one end of the coil pattern 4b are connected by a through hole 9d.

  Small patterns 4f are provided around the through holes 9b and 9c in the surface layer L1 and around the through holes 9a and 9d in the back layer L3 in order to facilitate the formation of the through holes 9a to 9d. Each through-hole 9a-9d and the small pattern 4f are connected. The small pattern 4f is made of copper foil. The surface of the small pattern 4f of the surface layer L1 is subjected to insulation processing. Copper plating is given to the surface of each through hole 9a-9d. The insides of the through holes 9a to 9d may be filled with copper or the like.

  The other end of the coil pattern 4a is connected to the terminal 6i through the pad 8b. The other end of the coil pattern 4b is connected to the terminal 6o through a pad 8b.

  As described above, the coil patterns 4a to 4e of the substrate 3 are the surface layer L1, and after the first time is wound around the convex portion 2L from the terminal 6i that is the starting point, the intermediate layer L2 is passed through the through hole 9a. Connected to. Next, in the intermediate layer L2, the second time is wound around the convex portion 2L, and then connected to the back surface layer L3 via the through hole 9c.

  Next, the coil pattern is the back surface layer L3, the third time is wound around the convex portion 2L, the fourth time is wound around the convex portion 2r via the periphery of the convex portion 2m, and then the through hole is formed. It is connected to the intermediate layer L2 via 9b. Next, the coil pattern is the intermediate layer L2, and after the fifth round is wound around the convex portion 2r, it is connected to the surface layer L1 via the through hole 9d. The coil pattern is the surface layer L1, and after the sixth time is wound around the convex portion 2r, the coil pattern is connected to the terminal 6o that is the end point.

  As described above, the current flowing through the magnetic device 1 is also the terminal 6i, the coil pattern 4a, the through hole 9a, the coil pattern 4c, the through hole 9c, the coil pattern 4e, the through hole 9b, the coil pattern 4d, the through hole 9d, and the coil pattern. 4b and terminal 6o in this order.

  The heat radiation patterns 5a to 5e are formed separately from the patterns 4a to 4e and 4f in empty areas around the coil patterns 4a to 4e and the small patterns 4f of the layers L1 to L3.

  The pads 8b, the terminals 6i and 6o, the through holes 3a, and the screws 11 are insulated from the heat radiation patterns 5a to 5e. As shown in FIG. 3, the shortest insulation distance S1 between the through-hole 3a in the surface layer L1 and the heat radiation pattern 5a is larger than the shortest insulation distance S2 between the through-hole 3a in the intermediate layer L2 and the back surface layer L3 and the heat radiation patterns 5b to 5e. It is getting bigger.

  This is because the head portion 11a having a larger diameter than the shaft portion 11b of the screw 11 is disposed on the surface side of the substrate 3, so that the head portion 11a and the heat radiation pattern 5a are insulated. That is, the board 3 and the heat sink 10 are fixed by the screw 11 in the regions R1 and R2 where no conductor exists in each of the layers L1 to L3 of the board 3.

  As shown to Fig.3 (a), in the surface layer L1, the thermal radiation pin 7a and this surrounding pad 8c are connected with respect to the coil pattern 4a. Further, the heat radiation pin 7b and the surrounding pad 8c are connected to the coil pattern 4b. The heat radiation pins 7c to 7f and the surrounding pad 8c are insulated from the heat radiation pattern 5a. Further, the coil patterns 4a, 4b and the small pattern 4f are insulated from the heat radiation pattern 5a.

  As shown in FIG. 3B, in the intermediate layer L2, heat radiation pins 7c and 7e are connected to the coil pattern 4c. In addition, heat radiation pins 7d and 7f are connected to the coil pattern 4d. The heat radiation pin 7a is insulated from the heat radiation pattern 5b. The coil patterns 4c and 4d are insulated from the heat radiation pattern 5b.

  As shown in FIG.3 (c), in the back surface layer L3, the thermal radiation pins 7a-7f and the surrounding pad 8c are connected with respect to the thermal radiation patterns 5c-5e. Further, the coil pattern 4e and the small pattern 4f are insulated from the heat radiation patterns 5c to 5e.

  That is, the coil patterns 4a and 4b on the front surface layer L1 and the left and right heat radiation patterns 5e on the back surface layer L3 are connected by the heat radiation pins 7a and 7b, respectively. Further, the coil patterns 4c and 4d of the intermediate layer L2 and the left and right heat dissipation patterns 5c and 5d of the back surface layer L3 are connected by the heat dissipation pins 7c to 7f, respectively.

  As shown in FIG. 3, in the surface layer L1 and the back surface layer L3, the surface areas of the through holes 8a, 8d, 9a to 9d, which are conductors, the pads 8b and 8c, the terminals 6i and 6o, the small pattern 4f, and the pins 7a to 7f. Are the same. Further, the total surface area of the coil patterns 4a and 4b of the surface layer L1 is larger than the surface area of the coil pattern 4e of the back surface layer L3.

  On the other hand, the total surface area of the heat radiation patterns 5c to 5e of the back surface layer L3 is wider than the surface area of the heat radiation pattern 5a of the front surface layer L1. This is apparent when attention is paid to the regions R1 and R2 around the screw 11. The difference in surface area between the heat radiation patterns 5a, 5c to 5e of the surface layer L1 and the back surface layer L3 is larger than the difference in surface area between the coil patterns 4a, 4b, 4e.

  Therefore, the area of the conductor provided in the surface layer L1 (the total of the through holes 8a, 8d, 9a to 9d, the pads 8b and 8c, the terminals 6i and 6o, the patterns 4a, 4b, 4f, and 5a, and the pins 7a to 7f) Area of the conductors (through holes 8a, 8d, 9a-9d, pads 8b, 8c, terminals 6i, 6o, patterns 4e, 4f, 5c-5e, and pins 7a-7f provided on the back surface layer L3. The total surface area) is wider.

  In the surface layer L1 and the intermediate layer L2, the surface areas of the through-holes 8a, 8d, 9a-9d, terminals 6i, 6o, and pins 7a-7f, which are conductors, are the same. Further, there is almost no difference in the surface areas of the patterns 4a, 4b, 4c, 4d, and 4f of the surface layer L1 and the intermediate layer L2. Further, the pads 8b and 8c in the surface layer L1 are not in the intermediate layer L2.

  On the other hand, the surface area of the heat dissipation pattern 5b of the intermediate layer L2 is larger than the surface area of the heat dissipation pattern 5a of the surface layer L1. This is apparent when attention is paid to the regions R1 and R2 around the screw 11. The difference in surface area between the heat radiation patterns 5a and 5b of the surface layer L1 and the intermediate layer L2 is larger than the surface area of the pads 8b and 8c.

  Therefore, the area of the conductor provided in the surface layer L1 (the total of the through holes 8a, 8d, 9a to 9d, the pads 8b and 8c, the terminals 6i and 6o, the patterns 4a, 4b, 4f, and 5a, and the pins 7a to 7f) The surface area of the conductor provided in the intermediate layer L2 (the total surface area of the through holes 8a, 8d, 9a to 9d, the terminals 6i and 6o, the patterns 4c, 4d, and 5b, and the pins 7a to 7f) is larger than the surface area). It has become.

  Since a large current flows through the coil patterns 4a to 4e, the coil patterns 4a to 4e serve as heat generation sources, and the temperature of the substrate 3 rises.

  In the surface layer L1, the heat of the substrate 3 is diffused to a conductor such as the heat radiation pattern 5a and is radiated on the surface of the conductor. The heat of the substrate 3 is radiated by the heat sink 10 through the insulating sheet 12 through conductors that penetrate the substrate 3 such as the heat radiation pins 7a and 7f and the through holes 8d, 8a, and 9a to 9d.

  In particular, the heat generation of the coil patterns 4a and 4b of the surface layer L1 is transmitted through the heat dissipation pins 7a and 7b, the terminals 6i and 6o, the through holes 8d, 8a, 9a and 9d, and the heat dissipation pattern 5e of the back surface layer L3, and the insulating sheet. Heat is radiated by the heat sink 10 through 12. The through holes 9a to 9d also function as thermal vias.

  In the intermediate layer L2, the heat of the substrate 3 is diffused to a conductor such as the heat dissipation pattern 5b. The heat of the substrate 3 is radiated by the heat sink 10 via the insulating sheet 12 through conductors that penetrate the substrate 3 such as the heat radiation pins 7c to 7f and the through holes 8d and 9a to 9d.

  In particular, the heat generation of the coil patterns 4c and 4d of the intermediate layer L2 is transmitted through the heat radiation pins 7c, 7d, 7e and 7f, the through holes 8d and 9a to 9d, and the heat radiation patterns 5c and 5d of the back surface layer L3 to the insulating sheet 12. The heat sink 10 dissipates heat.

  In the back layer L3, the heat of the substrate 3 is diffused to conductors such as the heat radiation patterns 5c to 5e and the heat radiation pins 7a to 7f. The heat diffused in these conductors is radiated by the heat sink 10 through the insulating sheet 12. In particular, the heat generated by the coil pattern 4e is radiated by the heat sink 10 through the insulating sheet 12 from the surface of the coil pattern 4e.

  According to the first embodiment, the heat of the substrate 3 provided with the coil patterns 4a to 4e is easily transferred to the heat sink 10 from the conductor having a large area provided on the back surface layer L3. can do. Thereby, heat_generation | fever of the coil patterns 4a-4e is accept | permitted. As a result, it is not necessary to increase the width over the entire length of the coil patterns 4a to 4e so that the amount of generated heat is reduced, and the magnetic device 1 can be prevented from being enlarged.

  Moreover, since the coil patterns 4a to 4e and the heat radiation patterns 5a to 5e are provided in the layers L1 to L3 of the substrate 3, the heat of the substrate 3 can be radiated from the front surface side and the back surface side of the substrate 3.

  In particular, in the back surface layer L3, heat can be efficiently transmitted from the surface of the coil pattern 4e and the heat radiation patterns 5c to 5e to the heat sink 10 to be radiated. Moreover, in the surface layer L1, heat can be radiated from the surfaces of the coil patterns 4a and 4b and the heat radiation pattern 5a.

  Further, by fixing the substrate 3 and the heat sink 10 with the screws 11 in the regions R1 and R2 where the conductors of the substrate 3 do not exist, the screws 11 and the conductors of the substrate 3 can be securely connected even if the screws 11 are not insulated. Can be insulated.

  Further, by arranging the head 11a of the screw 11 on the surface layer L1 side of the substrate 3 and providing a region R1 in which no conductor exists around the head 11a, the back surface layer L3 from the area of the conductor of the surface layer L1. The area of the conductor can be easily increased.

  Furthermore, by sandwiching the insulating sheet 12 having heat conductivity between the substrate 3 and the heat sink 10, the substrate 3 and the heat sink 10 can be insulated without applying insulation processing to the back surface layer L3 of the substrate 3, The heat of the substrate 3 can be transferred to the heat sink 10.

  In the first embodiment, the example in which the heat radiation patterns 5a to 5e are provided separately from the coil patterns 4a to 4e on the respective layers L1 to L3 of the substrate 3 has been described, but the present invention is not limited to this. As in the second embodiment described below, a heat radiation pattern integrated with the coil pattern may be provided.

  FIG. 5 is a plan view of each layer of the substrate 3 ′ of the magnetic device 1 ′ according to the second embodiment. FIG. 6 is a cross-sectional view of the magnetic device 1 ′ and shows a ZZ cross-section of FIG. 5.

  As shown in FIG. 6, the cores 2 a ′ and 2 b ′ made of a magnetic material are configured by a pair of an upper core 2 a ′ having an E-shaped cross section and a lower core 2 b ′ having an I shape. Of the convex portions 2m ′, 2L ′ and 2r ′ projecting downward from the upper core 2a ′, the lower ends of the left and right convex portions 2L ′ and 2r ′ are brought into close contact with the upper surface of the lower core 2b ′, and the core 2a ′. 2b 'are combined. A gap having a predetermined size is provided on the upper surface of the protrusion 2m 'of the upper core 2a' and the lower core 2b '. The cores 2a 'and 2b' are fixed by fixing means such as screws or metal fittings (not shown). The lower core 2 b ′ is fitted into a recess 10 k provided on the upper side of the heat sink 10.

  The substrate 3 'is composed of a thick copper foil substrate having a surface layer L1', an intermediate layer L2 ', and a back surface layer L3'. As shown in FIG. 5, the central protrusion 2m 'of the cores 2a' and 2b 'passes through the through hole 3m' of the substrate 3 '. The left and right notches 3k have left and right protrusions 2L 'and 2r' of the cores 2a 'and 2b'.

  The back surface of the substrate 3 ′ is opposed to the upper surface of the heat sink 10, and as shown in FIG. 6, the screw 11 is passed through the through hole 3 a from the surface side of the substrate 3 ′ and screwed into the screw hole 10 a of the heat sink 10. Thereby, the heat sink 10 is fixed to the back surface side of the substrate 3 ′ in the proximity state. An insulating sheet 12 is sandwiched between the substrate 3 ′ and the heat sink 10.

As shown in FIG. 5, the substrate 3 ′ has through holes 8a, 8d, 9a ′, 9b ′, pads 8b, 8c, terminals 6i, 6o, patterns 4a ′, 4b ′, 4c ′, 4f ′, 5t _0. Conductors such as ˜5t ₆ , 5s _{0 to} 5s ₉ , and pins 7g _{0 to} 7g ₃ are provided. Terminals 6i and 6o are respectively embedded in the through holes 8a. Pads 8b are provided around the terminals 6i and 6o of the surface layer L1 ′ and the back surface layer L3 ′.

The through hole 8d, the heat dissipation pins _7g 0 _{~7g 3} are embedded respectively. The heat dissipation pins 7g _{0 to} 7g ₃ are made of copper pins, and the surfaces thereof are plated with copper. Around the heat radiating fin _7g 0 _{~7g 3} of the surface layer L1 'and the back surface layer L3', pad 8c is provided. The lower ends of the heat radiation pins 7 g _{0 to} 7 g ₃ are in contact with the insulating sheet 12.

In each of the layers L1 ′ to L3 ′, coil patterns 4a ′ to 4c ′ and heat radiation patterns 5t _{0 to} 5t ₆ and 5s _{0 to} 5s ₉ are provided. Each pattern _{4a'~4c ', 5t 0 ~5t 6,} 5s 0 ~5s 9 is made of a copper foil. 'Each pattern 4a'~4c of' surface layer _L1, on the surface of _{5t 0 ~5t 6, 5s 0 ~5s} 9, insulating treatment is applied. The width, thickness, and cross-sectional area of the coil patterns 4a ′ to 4c ′ can suppress the amount of heat generated from the coil patterns 4a ′ to 4c ′ to a certain extent even when a predetermined large current (for example, DC 150A) flows. It is set so that heat can be radiated from the surface of the patterns 4a ′ to 4c ′.

In each layer L1 ′ to L3 ′, the coil pattern 4a ′
˜4c ′ is wound twice around the central protrusion 2m ′. One end of the coil pattern 4a ′ and one end of the coil pattern 4b ′ are connected by a through hole 9a ′. The other end of the coil pattern 4b ′ and one end of the coil pattern 4c ′ are connected by a through hole 9b ′. The other end of the coil pattern 4a ′ is connected to the terminal 6o via the pad 8b on the surface layer L1 ′. The other end of the coil pattern 4c ′ is connected to the terminal 6i through the pad 8b on the back surface layer L3 ′.

  Small patterns 4 f ′ made of copper foil are provided around the through hole 9 b ′ of the surface layer L <b> 1 ′ and around the through hole 9 a ′ of the back surface layer L <b> 3 ′. The respective through holes 9a 'and 9b' are connected to the small pattern 4f '. The surface of the small pattern 4f 'of the surface layer L1' is subjected to insulation processing. Copper plating is applied to the surface of each through hole 9a ', 9b'.

As described above, the coil patterns 4a ′ to 4c ′ of the substrate 3 ′ are the back surface layer L3 ′, and after the first and second times are wound around the convex portion 2m ′ from the starting terminal 6i, the through hole 9b It is connected to the intermediate layer L2 'via'. Next, the coil pattern is the intermediate layer L2 ′, and after the third and fourth turns are wound around the convex portion 2m ′, the surface layer L1 ′ is passed through the through hole 9a ′.
Connected to. The coil pattern is the surface layer L1 ′, and after the fifth and sixth turns are wound around the convex portion 2m ′, the coil pattern is connected to the terminal 6o that is the end point. The current flowing through the magnetic device 1 ′ also flows along the above-described normal path.

The heat radiation patterns 5t _{0 to} 5t ₆ , 5s _{0 to} 5s ₉ are the layers L1 ′ to L3.
The coil patterns 4a 'to 4c' and the small pattern 4f 'are formed in empty areas around the coil patterns 4a' to 4c '. Among them, the heat radiation patterns 5t _{0 to} 5t ₆ are coil patterns 4a ′ to 4c.
By extending ', the coil patterns 4a' to 4c 'are formed integrally. The heat radiation patterns 5s _{0 to} 5s ₉ are coil patterns 4a ′ to 4c.
“, Small pattern 4 f” and heat radiation patterns 5 t _{0 to} 5 t ₆ are formed separately.

As shown in FIG. 5A, in the surface layer L1 ′, the heat radiation patterns 5s _{0 to} 5s ₂ are insulated from each other, and are further insulated from the heat radiation patterns 5t _{0 to} 5t ₂ and the coil pattern 4a ′. Radiation fins _{7 g} 0, 7 g ₁ and the peripheral pad 8c is provided respectively on the heat radiation pattern _5t 0, 5t _1, is connected to the heat radiation pattern _5t 0 _{~5t 2} and the coil patterns 4a '.

Further, 'in, the surrounding terminal 6o pad 8b is provided on the heat radiation pattern 5t _2, the heat radiation pattern _5t 0 ～5T ₂ and coil patterns 4a' surface layer L1 is connected to the heat radiation pattern _5s 0 ~ 5s ₂ and are insulated. The terminal 6i and the surrounding pad 8b are insulated from the coil pattern 4a ′ and the heat radiation patterns 5t _{0 to} 5t ₂ . The heat radiation pins 7g ₂ and 7g ₃ and the surrounding pad 8c are provided in the heat radiation patterns 5s ₁ and 5s ₂ , respectively, and are connected to the heat radiation patterns 5s ₁ and 5s _2, and the heat radiation patterns 5s ₀ , 5t _{0 to} 5t. ₂ and the coil pattern 4a ′.

As shown in FIG. 5B, in the intermediate layer L2 ′, the heat radiation patterns 5s ₃ , 5s ₄ are insulated from each other, and further, the heat radiation patterns 5t ₃ , 5t ₄ and the coil pattern 4b ′ are also insulated.

In the intermediate layer L2 ′, the heat radiation pins 7g ₂ and 7g ₃ and the surrounding through holes 8d are provided in the heat radiation patterns 5t ₃ and 5t ₄ , respectively, and the heat radiation patterns 5t ₃ and 5t ₄ and the coil pattern 4b. 'It is connected to the. Radiation fins _{7 g} 0, 7 g ₁ and through holes 8d in the surroundings is provided respectively on the heat radiation pattern _5s 3, 5s _4, is connected to the heat radiation pattern _5s 3, 5s _4, the heat radiation pattern _5t 3, 5t ₄ Ya It is insulated from the coil pattern 4b ′.

As shown in FIG. 5C, in the back surface layer L3 ′, the heat radiation patterns 5s _{5 to} 5s ₉ are insulated from each other, and are also insulated from the heat radiation patterns 5t ₅ , 5t ₆ and the coil pattern 4c ′. A heat dissipation pins _7g 0 _{~7g 3} pads 8c of the ambient is provided respectively on the heat radiation pattern _5s 5 _~5s within ₈ is connected to the heat radiation pattern _5s 5 _{~5s 8,} the heat radiation pattern _{5s 9,} 5t 5, 5t ₆ and the coil pattern 4c ′.

Further, the back surface layer L3 ', pad 8b of the surrounding terminal 6o is radiating pattern 5s provided within ₉ is connected to the heat radiation pattern 5s _9, the heat radiation pattern _{5s 5 ~5s 8, 5t 5,} 5t 6 And insulated from the coil pattern 4c ′. Pad 8b of the surrounding terminal 6i is provided on the heat radiation pattern 5t _5, the heat radiation pattern _5t 5, 5t _6, and is connected to the coil pattern 4c ', is insulated from the heat radiation pattern _5s 5 _{~5s 9} .

That is, by the heat dissipation pins _{7 g} 0, 7 g ₁ and terminal 6o, 'coil patterns 4a' of the surface layer L1, the heat radiation pattern _5t 0 _{~5t 2,} the intermediate layer L2 'radiating pattern _5s 3 _{~5s 4,} and the back surface layer L3' The heat radiation patterns 5s ₅ , 5t ₆ and 5t ₉ are connected.

Further, the heat radiation pins 7g ₂ and 7g ₃ allow the heat radiation patterns 5s ₁ and 5s ₂ of the surface layer L1 ′ and the coil pattern 4b ′ of the intermediate layer L2 ′.
The heat radiation patterns 5t ₃ and 5t ₄ and the heat radiation patterns 5s ₇ and 5s _{8 of the} back surface layer L3 ′ are connected.

As shown in FIG. 5, the through-hole 3 a and the screw 11 are insulated from the patterns 4 a ′ to 4 c ′, 4 f ′, 5 t _{0 to} 5 t ₆ , and 5 s _{0 to} 5 s ₉ in each layer L 1 ′ to L 3 ′. Yes. Pattern 4b ′ of the intermediate layer L2 ′ and the back surface layer L3 ′,
4c ′, 4f ′, 5t _{3 to} 5t ₆ , 5s _{3 to} 5s ₉ and the pattern 4a ′, 4f ′, 5t _{0 to} 5t ₂ , 5s _{0 to} 5s of the surface layer L1 ′ from the shortest insulation interval S2 of the through hole 3a. ₂ and the shortest insulation interval S1 between the through holes 3a are larger (see also FIG. 6). The substrate 3 ′ and the heat sink 10 are fixed by screws 11 in the regions R1 and R2 where the conductor of the substrate 3 ′ does not exist.

In the surface layer L1 ′ and the back surface layer L3 ′, the through holes 8a, 8d, 9a ′, 9b ′, which are conductors, the pads 8b, 8c, the terminals 6i, 6o, the small pattern 4f ′, and the surface areas of the pins 7g _{0 to} 7g ₃ Are the same. On the other hand, 'pattern 4a' of the surface layer _{L1, 5t 0 ~5t 2, 5s} 0 than the total surface area of ～5S _2, 'pattern 4c' of the back surface layer _L3, 5t _5, 5t _6, the total surface area of 5s 5 ~5s ₉ Is wider. This is apparent when attention is paid to the regions R1 and R2 around the screw 11.

Therefore, the area of the conductor provided in the surface layer L1 ′ (through holes 8a, 8d, 9a ′, 9b ′, pads 8b, 8c, terminals 6i, 6o, patterns 4a ′, 4f ′, 5t _{0 to} 5t ₂ , 5s _{0 to} 5 s ₂ and the total surface area of the pins 7 g _{0 to} 7 g ₃ ), the area of the conductor provided in the back surface layer L 3 ′ (through holes 8 a, 8 d, 9 a ′, 9 b ′, pads 8 b, 8 c, terminals 6 i, 6o, pattern _{4c ', 4f', 5t 5} , 5t 6, 5s 5 ~5s 9, and towards the total surface area) of the pin _7g 0 _{~7g 3} is wider.

Thereby, coil pattern 4a '-4c
Since heat generated when a large current flows through 'is easily transmitted to the heat sink 10 from a conductor having a large area provided on the back surface layer L3' of the substrate 3 ', the substrate 3' can be easily dissipated. Moreover, each layer L1'-L3 of board | substrate 3 '
Since coil patterns 4a 'to 4c' and heat radiation patterns 5t _{0 to} 5t ₆ and 5s _{0 to} 5s ₉ are provided in ' Can be made. As a result, the coil patterns 4a ′ to 4c are reduced so that the heat generation amount is reduced.
It is not necessary to increase the width over the entire length of ', and the magnetic device 1' can be prevented from becoming large.

In the present invention, various embodiments other than those described above can be adopted. For example, in the above embodiment, all the layers L1 to L3 and L1 ′ to L3 of the substrates 3 and 3 ′.
Although an example in which the coil patterns 4a to 4e and 4a 'to 4c' are formed in 'is shown, the present invention is not limited to this. A coil pattern may be formed on at least one layer of a substrate having a plurality of layers. Moreover, the coil pattern should just be wound by the at least 1 convex part of the core.

  In the above embodiment, the back surface layers L3 and L3 ′ of the substrates 3 and 3 ′ are not subjected to insulation processing, and the insulating sheet 12 is sandwiched between the substrates 3 and 3 ′ and the heat sink 10. However, the present invention is not limited to this. In addition to this, the insulating layers 12 may be omitted by applying an insulating process to the back surface layers L3 and L3 '. In this case, a heat transfer body is preferably sandwiched between the substrates 3 and 3 ′ and the heat sink 10.

  Moreover, although the example which used the heat sink 10 was shown as a heat radiator in the above embodiment, this invention is not limited only to this, Other air-cooled type or water-cooled type heat radiators, or refrigerant | coolants You may use the radiator etc. which used.

  Moreover, although the example using a thick copper foil board | substrate was shown in the above embodiment, this invention is not limited only to this, A general resin-made printed boards, metal boards, etc. Other substrates may be used. In the case of a metal substrate, an insulator may be provided between the base material and the coil pattern.

  Moreover, although the example which used the thermal radiation pin was shown in order to transmit heat | fever from one layer to another layer in the above embodiment, this invention is not limited only to this. Through holes may be used instead of heat dissipation pins to transfer heat from one layer to another. Conversely, a heat dissipation pin may be used instead of the through hole.

  In the above embodiment, an example in which the I-shaped lower cores 2b and 2b 'are combined with the E-shaped upper cores 2a and 2a' has been described. However, the present invention is applicable to a magnetic device having only an E-shaped core. Can also be applied.

  Furthermore, although the example which applied this invention to the magnetic device 1 used as the choke coil L of the smoothing circuit 55 in the switching power supply device 100 for vehicles in the above embodiment was given, as the transformer 53 (FIG. 1) The present invention can be applied to a magnetic device to be used. Further, the present invention can be applied to a magnetic device other than a vehicle, for example, used in a switching power supply device for electronic equipment.

1,1 'magnetic device 2a, 2a' on the core 2b, 2b 'lower core 3,3' substrate 4a~4e, 4a'~4c 'coil pattern 4f, 4f' small pattern _5a~5e, 5t 0 ~5t _6, 5s _{0 to} 5s ₉ Heat radiation pattern 6i, 6o Terminals 7a to 7f, 7g _{0 to} 7g ₃ Heat radiation pin 8a, 8d Through hole 8b, 8c Pad 9a, 9b, 9c, 9d, 9a ', 9b' Through hole 10 Heat sink 11 Screw 12 Insulating sheet L1, L1 ′ Surface layer L2, L2 ′ Intermediate layer L3, L3 ′ Back surface layer R1, R2 Region where no conductor exists

Claims (4)

A core made of magnetic material,
A substrate made of an insulator through which the core penetrates;
A magnetic device comprising a coil pattern wound around the core and provided on the substrate;
Provide a radiator on the back side of the substrate,
A magnetic device, wherein an area of the conductor provided on a back surface layer of the substrate is larger than an area of the conductor provided on a surface layer of the substrate. The magnetic device according to claim 1.
The conductor provided on the front surface layer and the back surface layer of the substrate,
The coil pattern;
And a heat radiation pattern formed integrally or separately with respect to the coil pattern. The magnetic device according to claim 1 or 2,
The magnetic device, wherein the substrate and the radiator are fixed with screws in a region of the surface layer of the substrate where the conductor does not exist. The magnetic device according to any one of claims 1 to 3,
A magnetic device, wherein an insulating sheet having heat conductivity is sandwiched between the substrate and the radiator.

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