Electronic devices

Abstract

To provide an electronic device that can reduce the difference in inductance. [Solution] The electronic device 20 comprises a substrate 30 and a coupled inductor 40. The coupled inductor 40 has a core 41 and a plurality of coils 42 arranged on the core 41, aligned in the X direction and magnetically coupled to each other. The coils 42 have a main body portion 421 wound around the core 41 and terminal portions 422, 423 connected to the main body portion 421. The conductor 33 of the substrate 30 is exposed on one surface 30a and includes lands 334, 335 joined to the terminal portions 422, 423, and unjointed conductors 338 provided in a position overlapping with the main body portion 421 in a plan view and not joined to the coils 42. The area of ​​the unjointed conductor 338 located directly below one coil 42 is smaller directly below the coils 42A, 42D, which are end coils, than directly below the coils 42B, 42C, which are intermediate coils.

Description

Technical Field

[0001] The disclosure in this specification relates to an electronic device.

Background Art

[0002] Patent Document 1 discloses a configuration in which the inductance of a coil can be adjusted. The description of the prior art document is incorporated herein by reference as an explanation of the technical elements in this specification.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a coupled inductor including a plurality of coils arranged in a predetermined direction and magnetically coupled to each other, the magnetic path lengths of the end coils and the intermediate coils are different, and a difference in inductance occurs between the end coils and the intermediate coils. In Patent Document 1, in order to adjust the inductance, an adjustment coil is arranged next to the coil. When an adjustment coil is arranged for the coupled inductor, since it magnetically couples with all the coils, the difference in inductance between the end coils and the intermediate coils cannot be reduced. From the above viewpoints, or from other viewpoints not mentioned, further improvements are required for an electronic device including a coupled inductor.

[0005] One object of the present disclosure is to provide an electronic device capable of reducing the difference in inductance.

Means for Solving the Problems

[0006] An electronic device according to one aspect of the disclosure is A substrate (30) having an insulating substrate (31) and a conductor (33) arranged on the insulating substrate, A coupled inductor (40) having a core (41) and a plurality of coils (42) arranged in the core, aligned in a predetermined direction perpendicular to the thickness direction of the substrate, and magnetically coupled to one another, Equipped with, The multiple coils include end coils (42A, 42D) located at the ends in a predetermined direction, and intermediate coils (42B, 42C) located between the end coils. The coil has a main body (421) wound around a core and terminal parts (422, 423) connected to the main body. The conductor includes lands (334, 335) exposed on one surface of the substrate and joined to the terminal portion, and an unjointed conductor (338) provided in a position overlapping with the main body portion in a plan view in the thickness direction of the board and not joined to the coil. The area of ​​a non-jointed conductor located directly beneath a single coil is smaller directly beneath the end coil than directly beneath the intermediate coil.

[0007] In the disclosed electronic device, the magnetic path of the end coil is longer than that of the intermediate coil. The longer the magnetic path, the smaller the inductance of the coil. On the other hand, a non-joint conductor located directly beneath the main body of the coil absorbs a portion of the magnetic flux passing outside the core. The larger the area of ​​the non-joint conductor located directly beneath the coil, the greater the reduction in magnetic flux and the smaller the inductance of the coil. According to the disclosed electronic device, since the non-joint conductor is positioned opposite to the length of the magnetic path, the difference in inductance between the end coil and the intermediate coil can be reduced.

[0008] The various embodiments disclosed in this specification employ different technical means to achieve their respective objectives. The reference numerals in parentheses in the claims are illustrative in their correspondence with the embodiments described later and are not intended to limit the technical scope. The objectives, features, and effects disclosed in this specification will become clearer by referring to the subsequent detailed description and the accompanying drawings. [Brief explanation of the drawing]

[0009] [Figure 1] It is a circuit diagram showing a power supply circuit and an ECU to which the electronic device according to the first embodiment is applied. [Figure 2] It is a plan view showing an electronic device. [Figure 3] In FIG. 2, it is a diagram showing the coupling inductor in a transmissive manner. [Figure 4] It is a perspective view showing a coupling inductor. [Figure 5] It is a plan view of the coupling inductor as seen from the upper surface side. [Figure 6] It is a plan view of the coupling inductor as seen from the lower surface side. [Figure 7] It is a perspective view showing a core. [Figure 8] It is a perspective view showing a coil. [Figure 9] It is a cross-sectional view taken along the line IX-IX of FIG. 2. [Figure 10] It is a diagram showing the flow of magnetic flux when a current is passed through the intermediate coil. [Figure 11] It is a diagram showing the flow of magnetic flux when a current is passed through the end coil. [Figure 12] It is a plan view showing a modification example. [Figure 13] In the electronic device according to the second embodiment, it is a plan view showing a coupling inductor. [Figure 14] It is a diagram showing the positional relationship between the coupling inductor and the non-junction conductor. [Figure 15] In the electronic device according to the third embodiment, it is a diagram showing the positional relationship between the coupling inductor and the non-junction conductor. [Figure 16] It is a cross-sectional view taken along the line XVI-XVI of FIG. 15. [Figure 17] It is a plan view showing the electronic device according to the fourth embodiment. [Figure 18] It is a plan view showing the electronic device according to the fifth embodiment.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, a plurality of embodiments will be described based on the drawings. In each embodiment, corresponding components may be denoted by the same reference numerals, and redundant descriptions may be omitted. When only a part of the configuration is described in each embodiment, the configuration of other embodiments described previously can be applied to other parts of the said configuration. Also, not only the combinations of configurations explicitly shown in the description of each embodiment, but also the configurations of a plurality of embodiments can be partially combined with each other as long as there is no problem with the combination, even if not explicitly shown.

[0011] (First Embodiment) The electronic device according to this embodiment includes a coupling inductor as will be described later. An electronic device including a coupling inductor can be applied to various electronic circuits such as a power supply circuit and a high-frequency circuit. The electronic device can be applied to an ECU including a power supply circuit or the like. ECU is an abbreviation for Electronic Control Unit.

[0012] <Power Supply Circuit and ECU> FIG. 1 is a circuit diagram showing an example of a power supply circuit and an ECU to which the electronic device according to this embodiment is applied. For convenience, in FIG. 1, some drivers constituting the secondary power supply circuit are shown in a simplified manner.

[0013] The exemplary ECU 10 includes a primary power supply circuit 11, a secondary power supply circuit 12, and a processor 13. The electronic device described later may provide a part of the secondary power supply circuit 12, or may provide the entire secondary power supply circuit 12. The electronic device may provide the secondary power supply circuit 12 and the processor 13. The electronic device may provide the entire ECU 10. The ECU 10 may be mounted on, for example, a moving body. The moving body is, for example, a vehicle, an aircraft, a ship, a construction machine, an agricultural machine, or the like. The moving body may be a manned moving body or an unmanned moving body.

[0014] The example ECU10 is installed in a vehicle. ECU10 may be, for example, an autonomous driving ECU, or an ADAS ECU that performs controls to assist the driver's driving operations. ADAS is an abbreviation for Advanced Driving Assistant System. For example, levels 3 to 5 as defined by the Society of Automotive Engineers (SAE International) correspond to autonomous driving levels, and levels 1 to 2 correspond to driver assistance levels. ECU10 may also be an infotainment system ECU or a cockpit ECU. A cockpit ECU is an ECU that controls the meter system, navigation system, air conditioning system, etc. ECU10 may also be, for example, an integrated ECU that integrates multiple control functions.

[0015] The primary power supply circuit 11 is configured to step down the input voltage to a predetermined voltage and output it. The primary power supply circuit 11 is a step-down DC-DC converter. The illustrated primary power supply circuit 11 generates a constant voltage (e.g., 5V) lower than the power supply voltage (+B) based on power supplied from a battery mounted in the vehicle.

[0016] The secondary power supply circuit 12 uses the voltage generated by the primary power supply circuit 11 as its input voltage Vin. The secondary power supply circuit 12 steps down the input voltage Vin to a predetermined voltage (for example, around 1V) and outputs it to the load as the output voltage Vout. The secondary power supply circuit 12 is a step-down DC-DC converter. The secondary power supply circuit 12 includes multiple drivers 121, coupling inductors 122, and capacitors 123. The secondary power supply circuit 12 is a multi-phase power supply having multiple phases. Phases are sometimes referred to as stages or channels.

[0017] The driver 121 has switching elements 121H and 121L. The switching elements 121H and 121L are connected in series between the power supply line to which the input voltage Vin is input and the ground (GND) line, with switching element 121H on the high side and switching element 121L on the low side. The switching elements 121H and 121L may be MOSFETs or IGBTs. The switching elements 121H and 121L may also be bipolar transistors. MOSFET is an abbreviation for Metal Oxide Semiconductor Field Effect Transistor. IGBT is an abbreviation for Insulated Gate Bipolar Transistor.

[0018] The coupled inductor 122 has multiple inductors 122L that are magnetically coupled to each other. One end of the inductor 122L is connected to the connection point (midpoint) of the switching elements 121H and 121L. The other end of the inductor 122L is connected to the output line. The inductors 122L are provided individually for each driver 121. The driver 121 and inductor 122L for each phase are connected in parallel to each other. Parallelization can increase the output current from the multiphase power supply, i.e., the load current. The number of phases of the multiphase power supply is not particularly limited. The example multiphase power supply (secondary power supply circuit 12) has four phases.

[0019] Capacitor 123 is connected to the output line. The positive terminal of capacitor 123 is connected to the output line. The negative terminal of capacitor 123 is connected to ground. Capacitor 123 may be provided individually for each phase, or it may be provided in common for multiple phases. In the example, capacitor 123 is provided for each phase. Providing it for each phase allows capacitor 123 to be placed closer to inductor 122L, shortening the return path from capacitor 123. This can improve emissions.

[0020] The ECU 10 may include a control unit (not shown) of the secondary power supply circuit 12. The control unit performs voltage mode control, for example, by feedback of the output voltage Vout, and controls the operation of the driver 121, i.e., the operation of the switching elements 121H and 121L. The control unit determines the pulse width (duty cycle) of the PWM signal based on the output voltage Vout and controls the output voltage Vout of the multiphase power supply. The control unit may perform current mode control instead of voltage mode control. PWM is an abbreviation for Pulse Width Modulation.

[0021] The control unit synchronously controls the multiple drivers 121 so that they switch in different phases from each other. By using multiple phases in this way, the switching frequency can be artificially increased even if the switching frequencies of the multiple drivers 121 are the same. This makes it possible to reduce the ripple component of the output voltage Vout and improve responsiveness. The control unit switches the number of drivers 121 to be switched, i.e., the number of drive phases, according to the load current. The control unit compares the load current with the threshold current and increases and / or decreases the number of drive phases according to the comparison result.

[0022] The processor 13 is an example of a load that operates by receiving power from the secondary power supply circuit 12. The processor 13 is, for example, a CPU or a GPU. CPU is an abbreviation for Central Processing Unit. GPU is an abbreviation for Graphics Processing Unit. The ECU 10 may have only one processor 13 or may have multiple processors 13. The ECU 10 may have multiple types of processors 13. The processor 13 may also be included in an SoC or SiP. An SoC is a single semiconductor chip on which multiple components necessary to realize the functions of a system or device are implemented. SoC is an abbreviation for System On Chip. SiP is an abbreviation for System in Package.

[0023] The processor 13 executes predetermined control processes by running a control program stored in memory (not shown). Memory is a non-transitory tangible storage medium that non-temporarily stores programs and data that can be read by the computer.

[0024] The core voltage of processor 13 is around 1V (for example, less than 1V), and the load current is several tens of amperes or more (for example, 100A or more). To handle such low voltage and high current, ECU 10 employs a multi-phase power supply as its power supply circuit. The multi-phase power supply steps down the input voltage to a voltage corresponding to the core voltage of processor 13 and outputs it. By using a multi-phase power supply, it is possible to accommodate the increased performance of processor 13 due to improvements in autonomous driving levels and advancements in infotainment functions, and in particular, to support autonomous driving level 3 and above.

[0025] In a high-performance processor 13, the current consumption fluctuates rapidly depending on the calculation process, requiring many capacitors 123 to supply a stable voltage even during sudden load changes. By using coupled inductors 122, the magnetic fields cancel each other out between phases, reducing the effective inductance value and improving responsiveness during sudden load changes. This allows for a significant reduction in the number of capacitors 123 compared to a configuration using a normal single inductor. For example, the size of the secondary power supply circuit 12, and consequently the size of the ECU 10, can be reduced.

[0026] <Outline configuration of electronic device> Figure 2 is a plan view showing an example of an electronic device. Figure 2 is a magnified view of the area around a coupled inductor within the electronic device. In Figure 2, wiring covered with resist is shown with dashed lines. Figure 3 is a view of Figure 2 with the coupled inductor transparent. For convenience, the resist is omitted in Figure 2. In Figure 2, the outer edge of the core is shown with a dashed line, and the coil is shown with a dashed line.

[0027] As shown in Figures 2 and 3, the electronic device 20 comprises a substrate 30 and several components mounted on the substrate 30. These components include a coupling inductor 40, a switching device 50, and a capacitor 60. The electronic device 20 provides the multi-phase power supply (secondary power supply circuit 12) described above. The electronic device 20 may also provide an ECU 10. In this case, elements of the processor 13 and the primary power supply circuit 11 are also mounted on the substrate 30. The electronic device 20 may also include a housing that accommodates other elements constituting the electronic device 20.

[0028] In the following, the thickness direction of the substrate is referred to as the Z direction. The direction perpendicular to the Z direction and in which multiple coils are arranged is referred to as the X direction. The direction perpendicular to both the Z and X directions is referred to as the Y direction. Unless otherwise specified, the shape viewed from the Z direction, in other words, the shape along the XY plane defined by the X and Y directions, is referred to as the planar shape. The view from the Z direction is sometimes simply referred to as the planar view. The positional relationship where B, located below A, overlaps with A in a planar view is sometimes referred to as B located directly below A.

[0029] The substrate 30 is sometimes referred to as a printed circuit board, printed wiring board, or wiring board. The substrate 30 has an insulating substrate 31, a resist 32, and a conductor 33. The insulating substrate 31 is formed using an electrical insulating material such as resin. The resist 32 is a so-called solder resist. In the Z direction, the resist 32 covers the side of the insulating substrate 31 to which components are soldered. In the example electronic device 20, the coupling inductor 40, the switching device 50, and the capacitor 60 are arranged on one side 30a of the substrate 30. The resist 32 is arranged on the insulating substrate 31 on at least one side 30a.

[0030] The conductor 33 is arranged on the insulating substrate 31. At least a portion of the conductor 33 forms a circuit together with components mounted on the substrate 30. The conductor 33 has wiring. The wiring is formed, for example, by patterning metal foil. The wiring is arranged on the surface layer on at least one side 30a. In addition to the surface layer on the one side 30a, the wiring may also be arranged on the surface layer on the back side, or it may be arranged inside the insulating substrate 31. The substrate 30 may be a single-sided substrate, a double-sided substrate, or a multilayer substrate including three or more layers of wiring. The conductor 33 may have, for example, via conductors. Via conductors are formed by placing a conductor, such as plating, in through holes (vias) formed in the insulating layer constituting the insulating substrate 31. Via conductors electrically connect wiring between different layers.

[0031] The illustrated substrate 30 is a multilayer substrate. The wiring includes wirings 331, 332, and 333 arranged on the surface layer on one side 30a. Wiring 331 electrically connects the coil 42 and the switching device 50. Wiring 331 is provided individually for the coil 42. The illustrated wiring 331 extends in the Y direction. Multiple wirings 331 are aligned in the X direction.

[0032] Wiring 332 is an output wire. Wiring 332 branches into multiple sections at one end, allowing for individual connection to the coil 42, and these sections are interconnected at the other end to form a common wire. The branched sections of wiring 332 electrically connect the coil 42 and the capacitor 60. The common wire electrically connects the coil 42 and the capacitor 60 to the output terminals of the multiphase power supply. The illustrated wiring 332 extends in the Y direction. Wiring 332 has four branched sections. The multiple branched sections are aligned in the X direction. Wiring 332 is located at a distance from wiring 331 in the Y direction. The coupled inductor 40 is located between wiring 332 and wiring 331 in the Y direction.

[0033] Wiring 333 is a ground wire. The ground wire provides a ground potential, which is the reference potential on the substrate 30. Wiring 333 is electrically connected to the inner layer ground wire, for example, via a via conductor (not shown). The branching portions of wiring 333 and wiring 332 are alternately aligned in the X direction. The example wiring includes five wirings 333.

[0034] The conductor 33 has lands 334, 335, 336, and 337. A land is a portion of the wiring that is exposed from the resist 32 so that it can be soldered to a component. The land may have an over-resist structure in which the outer edge is covered by the resist 32, or it may have a normal resist structure in which the outer edge is not covered by the resist 32. The lands 334, 335, 336, and 337 are arranged on the surface layer of one side 30a of the insulating substrate 31 and provide wiring functionality.

[0035] Lands 334 and 335 are provided corresponding to the coil 42 of the coupled inductor 40. Land 334 is provided at the end of wiring 331 on the coupled inductor 40 side. Land 335 is provided at the end of wiring 332 on the coupled inductor 40 side. Land 334 is provided at a distance from land 335 in the Y direction. The terminal portion 422 of the coil 42 is joined to land 334 via solder 70, and the terminal portion 423 is joined to land 335 via solder 70.

[0036] The example substrate 30 has four lands 334 and four lands 335. The four lands 334 are aligned in the X direction. The four lands 335 are aligned in the X direction. The lands 334 and 335 that are soldered to the same coil 42 are offset in the X direction. The lands 334 and 335 are arranged alternately in the X direction. Lands 334 and 335 that are adjacent in the X direction may have a small gap between them, or their ends may be approximately coincident in the X direction so that there is no gap between them.

[0037] Lands 336 and 337 are provided corresponding to capacitor 60. Land 336 is provided at the X-direction end of the branch portion of wiring 332. Lands 336 are provided at both ends in the X-direction at each branch portion. Land 337 is provided at the X-direction end of wiring 333. In the three wirings 333 located between the branch portions, land 337 is provided at both ends in the X-direction. In the wirings 333 located at both ends in the X-direction, land 337 is provided on one end facing the branch portion. Lands 336 and 337 are provided so as to face each other in the X-direction. The positive terminal of capacitor 60 is soldered to land 336, and the negative terminal is soldered to land 337.

[0038] The conductor 33 has a non-jointed conductor 338 located at a position that overlaps with the coupled inductor 40 in a plan view. The non-jointed conductor 338 will be described later.

[0039] The coupled inductor 40 is located on one surface 30a of the substrate 30. The coupled inductor 40 provides the coupled inductor 122 described above. The coupled inductor 40 comprises a core 41 and a plurality of coils 42. The coils 42 provide the inductor 122L described above. The exemplary coupled inductor 40 comprises four coils 42. The plurality of coils 42 are aligned in the X direction. One end of each coil 42 is soldered to a land 334, and the other end of each coil 42 is soldered to a land 335. Details of the structure of the coupled inductor 40 will be described later.

[0040] The switching device 50 provides the driver 121 described above, i.e., the switching elements 121H and 121L. The switching device 50 is provided in correspondence with the coil 42. The example switching device 50 constitutes the switching elements 121H and 121L for one phase. One switching device 50 constitutes the driver 121 for one phase. The switching device 50 may also be a semiconductor package containing multiple semiconductor elements. Alternatively, a switching device 50 may be provided for each switching element 121H and 121L. Multiple switching devices 50 are arranged in the X direction. The switching devices 50 and the coupled inductor 40 are arranged in the Y direction. The switching device 50 is soldered to a land (not shown) provided at the end of the wiring 331 on the switching device 50 side.

[0041] Capacitor 60 provides the capacitor 123 described above. Capacitor 60 is, for example, a chip capacitor. In the Y direction, a coupling inductor 40 is arranged between capacitor 60 and the switching device 50. The positive terminal of capacitor 60 is soldered to land 336, and the negative terminal is soldered to land 337. Multiple example capacitors 60 are provided for each coil 42. Multiple capacitors 60 are arranged to bridge adjacent wirings 332, 333. Capacitors 60 corresponding to one coil 42 are arranged in the Y direction to form a capacitor row. Multiple capacitors 60 corresponding to one coil 42 form multiple capacitor rows. Multiple capacitor rows are arranged in the X direction.

[0042] <Coupled Inductor> Figure 4 is a perspective view of the coupled inductor. Figure 5 is a plan view of the coupled inductor seen from above. Figure 6 is a plan view of the coupled inductor seen from below. In Figure 6, the boundary between the main body and the terminal section is indicated by a dashed line. Figure 7 is a perspective view of the core. Figure 8 is a perspective view of the coil.

[0043] As shown in Figures 2 to 8, the coupled inductor 40 comprises a core 41 and a plurality of coils 42. The coils 42 provide the inductor 122L described above. The plurality of coils 42 are arranged on a single core 41, that is, a common core 41, and are magnetically coupled to one another. By using the coupled inductor 40, the magnetic flux between phases is canceled out, and the effective inductance can be reduced.

[0044] The core 41 is formed using a magnetic material such as ferrite. The core 41 functions as a magnetic circuit. The core 41 has a plurality of core portions 411 and ends 412, 413. The coil 42 is inserted through the core 41. The core portions 411 are individually provided relative to the coil 42. The coil 42 is wound around the core portions 411. The core portions 411 extend in the Y direction. The plurality of core portions 411 are arranged in the X direction with predetermined intervals. The example core 41 has four core portions 411. Each core portion 411 is substantially rectangular parallelepiped in shape. The four core portions 411 have the same shape as each other.

[0045] The core portion 411 has an upper surface 411a, a lower surface 411b, and side surfaces 411c and 411d. The lower surface 411b is the surface facing the substrate 30 in the Z direction. The upper surface 411a is the surface opposite to the lower surface 411b in the Z direction. The side surface 411c is the surface opposite to the side surface 411d in the X direction.

[0046] Ends 412 and 413 are positioned opposite each other in the Y direction. Ends 412 and 413 have a core portion 411 in between them. Ends 412 and 413 extend in the X direction, which is the direction in which the multiple core portions 411 are aligned. One end of the multiple core portions 411 is connected to end 412, and the other end of the multiple core portions 411 is connected to end 413. Ends 412 and 413 magnetically connect the multiple core portions 411. The example ends 412 and 413 have the same shape as each other. Ends 412 and 413 are approximately rectangular parallelepipeds with the X direction as their longitudinal direction.

[0047] End portion 412 has an upper surface 412a, a lower surface 412b, and side surfaces 412c, 412d, 412e, and 412f. End portion 413 has an upper surface 413a, a lower surface 413b, and side surfaces 413c, 413d, 413e, and 413f. The lower surfaces 412b and 413b are the surfaces facing the substrate 30 in the Z direction. The upper surfaces 412a and 413a are the surfaces opposite to the lower surfaces 412b and 413b in the Z direction. The side surfaces 412c and 413c are the surfaces opposite to the side surfaces 412d and 413d in the X direction. Side surfaces 412e and 413e are surfaces facing each other in the Y direction. Side surfaces 412f and 413f are the surfaces opposite to the side surfaces 412e and 413e in the Y direction.

[0048] In the example core 41, the lower surfaces 411b, 412b, and 413b are approximately flush. The upper surfaces 412a and 413a are further away from the substrate 30 than the upper surface 411a. The upper surface 411a is closer to the substrate 30 than the upper surfaces 412a and 413a.

[0049] The coil 42 is formed using a metal material with good conductivity, such as copper. The coil 42 is formed by processing a metal sheet, not a metal wire. The metal sheet is sometimes referred to as a metal frame. Multiple coils 42 are formed from the same material and have the same shape. Multiple coils 42 have approximately equal inductance. Multiple coils 42 are arranged in the X direction with a predetermined spacing. Multiple coils 42 are arranged in the same orientation. The coils 42 are fixed to the core 41, for example, by adhesive.

[0050] The example coil 42 includes four coils 42A, 42B, 42C, and 42D. Coils 42A and 42D are end coils located at the ends in the X direction. Coil 42A is located at the end on the sides 412c and 413c. Coil 42D is located at the end on the sides 412d and 413d. Coils 42B and 42C are intermediate coils located between coils 42A and 42D. Coil 42B is located next to coil 42A. Coil 42C is located next to coil 42D. The multiple coils 42 are arranged in the order of coil 42A, coil 42B, coil 42C, and coil 42D in the X direction.

[0051] The coil 42 is formed by bending a metal plate material having a predetermined thickness. The coil 42 has a main body portion 421 and terminal portions 422 and 423. The terminal portions 422 and 423 are external connection terminals in the coil 42 and are soldered to the corresponding lands 334 and 335. Terminal portion 422 is soldered to land 334, and terminal portion 423 is soldered to land 335. The thickness direction of the terminal portions 422 and 423 is substantially parallel to the Z direction, and in the terminal portions 422 and 423, the lower surface, which is one of the plate surfaces, faces one surface 30a of the substrate 30. The upper surface, which is the other plate surface of terminal portion 422, faces the lower surface 412b of end portion 412. The upper surface of terminal portion 423 faces the lower surface 413b of end portion 413.

[0052] The example terminals 422 and 423 have a roughly rectangular shape in plan. Terminal 422 is connected to the lower wall 421a of the main body 421 and extends in the Y direction toward the side 412f, i.e., toward the switching device 50. Terminal 423 is connected to the lower wall 421b of the main body 421 and extends in the Y direction, in the opposite direction to terminal 422. Terminal 423 extends toward the side 413f, i.e., toward the capacitor 60. Terminals 422 and 423 connected to the same main body 421 are offset in the Y direction. Terminals 422 and 423 connected to the same main body 421 are offset in the X direction. Terminal 422 has approximately the same length as end 412 in the Y direction. Terminal 423 has approximately the same length as end 413 in the Y direction. The terminal portions 422 and 423 may extend outward beyond the corresponding ends 412 and 413 in a plan view.

[0053] The main body portion 421 is the part wrapped around the core portion 411 of the core 41. In a plan view, the main body portion 421 is the part that overlaps with the core portion 411. The main body portion 421 has lower walls 421a, 421b, side walls 421c, 421d, and an upper wall 421e.

[0054] The thickness direction of the lower walls 421a and 421b is approximately parallel to the Z direction. The lower surface, one of the surfaces of the lower walls 421a and 421b, faces one surface 30a of the substrate 30, and the upper surface, the other surface, faces the lower surface 411b of the core portion 411. The example lower walls 421a and 421b have a roughly rectangular shape in plan. A terminal portion 422 is attached to the end of the lower wall 421a on the side surface 412f. The lower wall 421a and the terminal portion 422 extend along the Y direction. A terminal portion 423 is attached to the end of the lower wall 421b on the side surface 413f. The lower wall 421b and the terminal portion 423 extend along the Y direction. The lower walls 421a and 421b have approximately the same length as the core portion 411 in the Y direction. The lower walls 421a and 421b of one main body section 421 are aligned in the X direction.

[0055] The side wall 421c is connected to the bottom wall 421a. The side wall 421c extends from the bottom wall 421a in the Z direction. The side wall 421c is opposite the side surface 411c of the core portion 411. The illustrated side wall 421c is substantially rectangular in a plan view in the X direction. The side wall 421c has approximately the same length as the bottom wall 421a in the Y direction. The side wall 421c is bent at an angle of approximately 90 degrees with respect to the bottom wall 421a. The thickness direction of the side wall 421c is substantially parallel to the X direction. The lower end of the side wall 421c is connected to the end of the bottom wall 421a opposite to the end facing the bottom wall 421b.

[0056] The side wall 421d is connected to the bottom wall 421b. The side wall 421d extends from the bottom wall 421b in the Z direction. The side wall 421d is opposite the side surface 411d of the core portion 411. The illustrated side wall 421d is substantially rectangular in a plan view in the X direction. The side wall 421d has approximately the same length as the bottom wall 421b in the Y direction. The side wall 421d is bent at an angle of approximately 90 degrees with respect to the bottom wall 421b. The thickness direction of the side wall 421d is substantially parallel to the X direction. The lower end of the side wall 421d is connected to the end of the bottom wall 421b opposite to the end facing the bottom wall 421a.

[0057] The upper wall 421e bridges the side walls 421c and 421d. The upper wall 421e extends in the X direction. One end of the upper wall 421e connects to the upper end of the side wall 421c, and the other end connects to the upper end of the side wall 421d. The upper wall 421e has the same length as the side walls 421c and 421d in the Y direction. In plan view, the upper wall 421e encompasses the entire areas of the side walls 421c and 421d, and the lower walls 421a and 421b.

[0058] The lower walls 421a, 421b, the side walls 421c, 421d, and the upper wall 421e surround the core portion 411 of the core 41. The lower walls 421a, 421b, the side walls 421c, 421d, and the upper wall 421e are attached to and wound around the core portion 411. The ends 412, 413 of the core 41 are positioned on the terminal portions 422, 423. The terminal portions 422, 423 include portions that are positioned closer to the substrate 30 than the lower surfaces 411b, 412b, 413b of the core 41. The lower surfaces of the terminal portions 422, 423 are located closer to one surface 30a than the lower surfaces 411b, 412b, 413b of the core 41.

[0059] In adjacent coils 42, one side wall 421c of coil 42 faces the other side wall 421d of coil 42. In the illustrated coupled inductor 40, the outer surface of the side wall 421c located at one end of the coupled inductor 40 is recessed relative to the sides 412c and 413c. Similarly, the outer surface of the side wall 421d located at the other end of the coupled inductor 40 is recessed relative to the sides 412d and 413d. The upper surface of the upper wall 421e of coil 42 is recessed relative to the upper surfaces 412a and 413a.

[0060] For example, the outer surface of the side wall 421c at one end may be made substantially flush with the sides 412c and 413c. The outer surface of the side wall 421d at the other end may be made substantially flush with the sides 412d and 413d. The upper surface of the upper wall 421e may be made substantially flush with the upper surfaces 412a and 413a.

[0061] The coupled inductor 40 may include a cover in addition to the core 41 and the plurality of coils 42. The illustrated coupled inductor 40 includes a cover 43. The cover 43 is positioned on the top surface of the core 41 and covers the core 41 and the plurality of coils 42. The cover 43 is used, for example, to suppress the adhesion of foreign matter to the coupled inductor 40. The cover 43 is used, for example, to suppress short circuits between the coils 42 due to conductive foreign matter. The cover 43 is used, for example, to improve the suction during transport when mounting the coupled inductor 40 to the substrate 30.

[0062] The constituent material of the cover 43 is not particularly limited as long as the above objective can be achieved. For example, it may be a resin or a magnetic material. The cover 43 may be made of the same material as the core 41. The cover 43 may function as part of the core 41. The illustrated cover 43 is a resin film or resin sheet. The cover 43 has a substantially rectangular shape in plan with the X direction as its longitudinal direction. The cover 43 is provided so as to enclose the core 41 and a plurality of coils 42 in plan view. The cover 43 is adhesively fixed to the upper surfaces 412a, 413a of the ends 412, 413.

[0063] <Non-jointed conductor> Figure 9 is a cross-sectional view along the line IX-IX in Figure 2. As shown in Figures 3 and 9, the substrate 30 has a non-jointed conductor 338. The non-jointed conductor 338 is not joined to the coil 42. The non-jointed conductor 338 is positioned to overlap with the main body 421 of the coil 42 in a plan view. The non-jointed conductor 338 is located directly below the main body 421. The non-jointed conductor 338 may be located only directly below the main body 421, or it may be located both directly below the main body 421 and directly below the unmounted portions of the terminal portions 422 and 423. The unmounted portions of the terminal portions 422 and 423 are the portions excluding the mounted portions that are soldered to the lands 334 and 335. The non-jointed conductor 338 is arranged such that the area of ​​the non-jointed conductor 338 located directly below one coil 42 is smaller directly below the end coil than directly below the intermediate coil.

[0064] The illustrated non-joint conductor 338, like the wiring 331, 332 and lands 334, 335, is located on the surface layer of one side 30a of the substrate 30. The non-joint conductor 338 is covered by the resist 32. The non-joint conductor 338 is located away from the lands 334, 335. The non-joint conductor 338 is electrically isolated from the wiring that constitutes the circuit. The non-joint conductor 338 is located only directly beneath the main body 421. The non-joint conductor 338 has a substantially rectangular shape in plan with the X direction as its longitudinal direction. The non-joint conductor 338 extends in the X direction so as to overlap with the four coils 42A, 42B, 42C, 42D. The substrate 30 has one non-joint conductor 338 located directly beneath the main body 421 across the four coils 42A, 42B, 42C, 42D.

[0065] In a plan view, the unjointed conductor 338 overlaps with almost the entire body portion 421 of coil 42B, which is an intermediate coil. In a plan view, the unjointed conductor 338 overlaps with almost the entire body portion 421 of coil 42C, which is an intermediate coil. In a plan view, the unjointed conductor 338 overlaps with a portion of the body portion 421 of coil 42A, which is an end coil. In a plan view, the unjointed conductor 338 overlaps with a portion of the lower wall 421b, the side wall 421d, and the upper wall 421e of the body portion 421 of coil 42A. In a plan view, the unjointed conductor 338 overlaps with a portion of the body portion 421 of coil 42D, which is an end coil. In a plan view, the unjointed conductor 338 overlaps with a portion of the lower wall 421a, the side wall 421c, and the upper wall 421e of the body portion 421 of coil 42D. In the X direction, the unjointed conductor 338 overlaps with the entire length of coils 42B and 42C. The non-jointed conductor 338 overlaps with a portion of coils 42A and 42D in the X direction.

[0066] <Summary of the First Embodiment> Figures 10 and 11 illustrate the flow of magnetic flux. Figure 10 shows the flow of magnetic flux when current is passed through coil 42C, which is the intermediate coil. Figure 11 shows the flow of magnetic flux when current is passed through coil 42D, which is the end coil. In Figures 10 and 11, the flow of magnetic flux is indicated by solid arrows. The magnitude of the magnetic flux is indicated by the thickness of the solid arrows. In both Figures 10 and 11, no non-jointed conductors are provided.

[0067] When current flows through one of the coils 42, a loop-shaped magnetic path is formed through the core portion 411 around which the other coils 42 are wound. Here, the inductance L of the coil is given by Equation 1. The magnetic resistance Rm is given by Equation 2. N is the number of turns of the coil. l is the length of the magnetic path. μ0 is the permeability of vacuum. μ is the impermeability. S is the cross-sectional area of ​​the magnetic path. From Equations 1 and 2, it is clear that the longer the length l of the magnetic path, the greater the magnetic resistance Rm, and as the magnetic resistance Rm increases, the magnetic flux generated by the same current decreases, and the inductance L decreases. (Formula 1)L=N 2 / Rm (Formula 2) Rm=l / μ0μS

[0068] From Figures 10 and 11, the magnetic path of coil 42D (end coil) is longer than that of coil 42C (middle coil). Therefore, the inductance of coil 42D is lower than that of coil 42C. When the inductances were measured, the inductance of the end coil was found to be about 8% lower than that of the middle coil.

[0069] In a multiphase power supply using a coupled inductor 40, if the inductance values ​​of the coils 42 differ, the current variation between phases will increase. Furthermore, differences will also occur in mutual inductance. This leads to variations in the current generated by magnetic coupling, worsening EMI. EMI stands for Electromagnetic Interference.

[0070] The electronic device 20 of this embodiment includes a substrate 30 and a coupled inductor 40. The coupled inductor 40 has a core 41 and a plurality of coils 42 arranged on the core 41, aligned in a predetermined direction perpendicular to the thickness direction of the substrate 30, and magnetically coupled to one another. The plurality of coils 42 include end coils located at the ends in the predetermined direction and intermediate coils located between the end coils. Each coil 42 has a main body portion 421 wound around the core 41 and terminal portions 422, 423 connected to the main body portion 421. The conductor 33 of the substrate 30 includes lands 334, 335 exposed on one surface 30a of the substrate 30 and joined to the terminal portions 422, 423, and unjointed conductors 338 provided in a position overlapping with the main body portion 421 in a plan view in the thickness direction and not joined to the coils 42. The area of ​​the unjointed conductor 338 located directly below one coil 42 is smaller directly below the end coils than directly below the intermediate coils. In the example electronic device 20, coils 42A and 42D correspond to end coils, and coils 42B and 42C correspond to intermediate coils. The Z direction corresponds to the plate thickness direction, and the X direction corresponds to a predetermined direction.

[0071] In the electronic device 20, the magnetic path of the end coil is longer than the magnetic path of the intermediate coil. The longer the magnetic path, the smaller the inductance of the coil 42. On the other hand, the non-joint conductor 338 located directly below the main body 421 of the coil 42 absorbs a portion of the magnetic flux passing outside the core 41. The larger the area of ​​the non-joint conductor 338 located directly below the coil 42, the greater the decrease in magnetic flux and the smaller the inductance of the coil 42. By making the area of ​​the non-joint conductor 338 directly below the end coil smaller than the area of ​​the non-joint conductor 338 directly below the intermediate coil, the absorption of magnetic flux by the non-joint conductor 338 in the end coil is weaker than in the intermediate coil, and the decrease in inductance due to magnetic flux absorption can be suppressed in the end coil more than in the intermediate coil. In this embodiment, since the non-joint conductor 338 is arranged opposite to the length of the magnetic path, the difference in inductance between the end coil and the intermediate coil can be reduced.

[0072] As illustrated, the non-jointed conductor 338 may be placed not only directly below the intermediate coil, but also directly below the end coils. This allows for adjustment of the area of ​​the non-jointed conductor 338 directly below the end coils relative to the area of ​​the non-jointed conductor 338 directly below the intermediate coil. Therefore, the degree of freedom in adjusting the inductance can be increased.

[0073] <Variation> The relationship between the area of ​​the non-jointed conductor 338 per intermediate coil and the area of ​​the non-jointed conductor 338 per end coil is not limited to the example described above.

[0074] While an example is shown where the areas of the non-jointed conductors 338 are approximately equal in multiple intermediate coils and approximately equal in multiple end coils, the invention is not limited to this example. To eliminate inductance differences caused by manufacturing variations of the coupled inductor 40, the areas of the non-jointed conductors 338 may be made different in multiple intermediate coils. Similarly, the areas of the non-jointed conductors 338 may be made different in multiple end coils.

[0075] An example has been shown in which a portion of one non-jointed conductor 338 is placed directly beneath the intermediate coil and another portion is placed directly beneath the end coil, but the substrate 30 is not limited to this. The substrate 30 may have multiple non-jointed conductors 338. For example, as shown in Figure 12, the non-jointed conductors 338 may be placed individually relative to the coils 42. In Figure 12, the substrate 30 has four non-jointed conductors 338. Although not shown, at least a portion of the non-jointed conductors 338 corresponding to multiple intermediate coils may be integrated. For example, in Figure 12, the non-jointed conductors 338 corresponding to two intermediate coils may be integrated, resulting in a configuration in which the substrate 30 has three non-jointed conductors 338.

[0076] An example of placing the non-jointed conductor 338 on the surface layer has been shown, but the method is not limited to this. The non-jointed conductor 338 may not be placed on the surface layer, but rather, for example, on the second layer or later. The closer the non-jointed conductor 338 is to the coil 42, the stronger the magnetic coupling becomes. Placing the non-jointed conductor 338 on the surface layer makes it possible to increase the effect of area differences on the inductance.

[0077] (Second Embodiment) This embodiment is a modification based on a prior embodiment, and the description of the prior embodiment can be referenced. In the prior embodiment, the core was not divided. Alternatively, the core may be divided into multiple parts. In the prior embodiment, the unjointed conductor overlapped with a portion of each end coil in the X direction. Alternatively, the unjointed conductor may overlap with the end coil over its entire length.

[0078] Figure 13 is a plan view showing a coupled inductor in the electronic device according to this embodiment. Figure 13 corresponds to Figure 6. As shown in Figure 13, the coupled inductor 40 of this embodiment has a core 411 of the core 411 that is divided into multiple parts. The core 411 is divided into multiple parts in the Y direction, which is the opposite direction of the ends 412 and 413. The example core 411 is divided at the center position in the Y direction. The core 411 includes two core parts 4111 and 4112. In the Y direction, the lengths of the core parts 4111 and 4112 are approximately equal.

[0079] The core portion 4111 is connected to the end portion 412. The core portion 4111 extends from the side surface 412e of the end portion 412 toward the end portion 413. The core portion 4112 is connected to the end portion 413. The core portion 4112 extends from the side surface 413e of the end portion 413 toward the end portion 412. The end portion 412 corresponds to the first end portion, and the end portion 413 corresponds to the second end portion. The core 41 has a gap 411g between the opposing surfaces of the core portion 4111 and the core portion 4112, where no magnetic member is placed. For example, adhesive is placed in the gap 411g to fix the core portion 4111 and the core portion 4112.

[0080] The division point is not limited to the center. A single core 411 may be connected to one of the ends 412, 413 and bonded to the other. The ends of a single core 411 may be bonded to the respective ends 412, 413. The core 411 may be divided into three or more parts.

[0081] If the core portion 411 has a gap 411g, magnetic flux will leak from the gap 411g. The coil 42 is wound around the core portion 411. However, there is no coil 42 (conductor) in the region between the lower wall 421a and the lower wall 421b. Therefore, magnetic flux is particularly prone to leaking from the area where the gap 411g and the region between the lower walls 421a and 421b overlap. Leakage flux worsens emissions.

[0082] Figure 14 shows the positional relationship between the coupled inductor and the uncoupled conductor in the electronic device according to this embodiment. In Figure 14, the coupled inductor is shown transparently. The resist is omitted in Figure 14. For convenience, the cover is omitted in Figure 14. The outer edge of the core is shown by a dashed line, and the coil is shown by a dashed line. In Figure 14, the land on which the coupled inductor is mounted is also shown. In Figure 14, the magnetic flux is shown by a solid arrow.

[0083] Similar to the prior embodiment, the electronic device 20 includes a non-jointed conductor 338 arranged to overlap with the main body portion 421 of the coil. Similar to the prior embodiment, the non-jointed conductor 338 is arranged to overlap with almost the entire area of ​​the intermediate coils 42B and 42C, and to overlap with a portion of the end coils 42A and 42D. In the X direction, the non-jointed conductor 338 is arranged to overlap with the main body portion 421 of coil 42A along the entire length of coil 42A. The non-jointed conductor 338 is arranged to overlap with the main body portion 421 of coil 42D along the entire length of coil 42D.

[0084] The unjointed conductor 338 has a widened portion 3381 and a narrowed portion 3382. The widened portion 3381 is longer than the narrowed portion 3382 in the Y direction. The narrowed portion 3382 is shorter than the widened portion 3381 in the Y direction. The widened portion 3381 is positioned to overlap with coils 42B and 42C in a plan view. The length of the widened portion 3381 in the Y direction is approximately equal to the length of the main body portion 421 in the Y direction. The narrowed portion 3382 is positioned to overlap with coils 42A and 42D in a plan view. The length of the narrowed portion 3382 in the Y direction is shorter than the length of the main body portion 421 in the Y direction. The widened portion 3381 extends in the X direction with a constant width, which is its length in the Y direction. The narrowed portion 3382 extends in the X direction with a constant width. The widened portion 3381 has a roughly rectangular shape in plan. The narrow section 3382 has a roughly rectangular shape in plan. The narrow section 3382 is connected to both ends of the widened section 3381 in the X direction.

[0085] The non-jointed conductor 338 is positioned to overlap with at least one gap 411g of the multiple core portions 411 in a plan view. The non-jointed conductor 338 is positioned to overlap with at least a portion of the gap 411g in one of the core portions 411. In the exemplary electronic device 20, the non-jointed conductor 338 is positioned to overlap with all of the gaps 411g of the corresponding core portions 411. The non-jointed conductor 338 is positioned to overlap with all of the gaps 411g in all of the core portions 411. The widened portion 3381 overlaps with the entire gap 411g of coil 42B and the entire gap 411g of coil 42C in a plan view. The narrowed portion 3382 overlaps with the entire gap 411g of coil 42A and the entire gap 411g of coil 42D in a plan view. Since a non-jointed conductor 338 is located directly below the gap 411g, leakage of magnetic flux from the gap 411g can be suppressed. The other configurations are the same as those described in the prior embodiment.

[0086] <Summary of the second embodiment> As illustrated, the non-jointed conductor 338 may be arranged so as to overlap with the main body 421 of the end coil over its entire length in a predetermined direction. In the illustrated electronic device 20, the X direction corresponds to the predetermined direction. Coils 42A and 42D correspond to the end coils. The non-jointed conductor 338 is arranged evenly, rather than being biased in the X direction relative to the end coil. This equalizes the magnetic coupling between the non-jointed conductor 338 and the end coil, improving the accuracy of inductance adjustment. Therefore, the effect of reducing the difference in inductance can be enhanced.

[0087] As illustrated, the core portion 411 of the core 41 of the coupled inductor 40 may be divided into multiple sections in the orthogonal direction, and may have gaps 411g. The non-jointed conductor 338 corresponding to the end coils may be arranged so as to overlap with the gaps 411g of the end coils in a plan view. In this case, the non-jointed conductor 338 (narrow portion 3382) arranged opposite the gaps 411g can suppress magnetic flux leakage from the gaps 411g. By providing the non-jointed conductor 338, magnetic flux leakage can be suppressed compared to a configuration without the non-jointed conductor 338, i.e., a configuration in which air is present. In particular, the effect can be enhanced by arranging the non-jointed conductor 338 so as to face the gaps 411g. This allows the inductance to be adjusted.

[0088] As illustrated, the non-jointed conductor 338 may be placed in the portion of the gap 411g that overlaps with the area between the lower walls 421a and 421b of the coil 42 in a plan view. The conductor constituting the coil 42 is wound around the core portion 411. However, the lower walls 421a and 421b are arranged with a predetermined distance between them. Therefore, magnetic flux is prone to leaking from the portion of the gap 411g that overlaps with the area between the lower walls 421a and 421b. By placing the non-jointed conductor 338 in the portion of the gap 411g that overlaps with the area between the lower walls 421a and 421b, magnetic flux leakage can be effectively suppressed.

[0089] As illustrated, the non-jointed conductor 338 may be arranged so as to overlap the entire gap 411g in one core portion 411. By arranging the non-jointed conductor 338 to face the entire area of ​​the gap 411g, magnetic flux leakage can be suppressed more reliably.

[0090] As illustrated, the non-jointed conductor 338 may be arranged to overlap with at least a portion of each of the gaps 411g between the multiple core portions 411. By arranging the non-jointed conductor 338 opposite to all of the multiple gaps 411g, leakage flux can be suppressed across the entire coupled inductor 40.

[0091] <Variation> For example, in a configuration in which the core portion 411 is not divided into multiple parts, the non-jointed conductor 338 may be arranged so as to overlap with the main body portion 421 of the end coil over its entire length in a predetermined direction.

[0092] In a configuration in which the non-jointed conductor 338 is divided into multiple parts, the non-jointed conductor 338 corresponding to the end coil may be arranged so as to overlap with the main body 421 over its entire length in a predetermined direction.

[0093] (Third embodiment) This embodiment is a modification based on the prior embodiment, and the description of the prior embodiment can be referenced. In the prior embodiment, a non-jointed conductor was placed directly below the end coil. Alternatively, a configuration in which a non-jointed conductor is not placed directly below the end coil may be used.

[0094] Figure 15 is a plan view showing a coupled inductor in the electronic device according to this embodiment. Figure 15 corresponds to Figure 14. In Figure 15, the coupled inductor is shown transparently. The resist is omitted. For convenience, the cover is omitted in Figure 15. The outer edge of the core is shown by a dashed line, and the coil is shown by a dashed line. Figure 15 also shows the lands on which the coupled inductor is mounted. Figure 16 is a cross-sectional view along the line XVI-XVI in Figure 15.

[0095] As shown in Figures 14 and 15, the non-jointed conductor 338 is located directly beneath the main body 421 of coils 42B and 42C. The non-jointed conductor 338 is not located directly beneath the main body 421 of coils 42A and 42D. In the illustrated electronic device 20, the non-jointed conductor 338 has a substantially rectangular shape in plan. The non-jointed conductor 338 overlaps with the entire area of ​​the main body 421 of coils 42B and 42C. The non-jointed conductor 338 is positioned to overlap with the gap 411g between coils 42B and 42C.

[0096] As shown in Figure 16, the non-jointed conductor 338, like the lands 334 and 335, is located on the surface layer of the substrate 30 on one side 30a. In the surface layer, the non-jointed conductor 338 is located directly beneath the coils 42B and 42C, but not directly beneath the coils 42A and 42D. In the second layer, which is adjacent to the surface layer, the conductor 33 is not located directly beneath the coils 42A and 42D. In other words, the conductor 33 that could function as a non-jointed conductor 338 does not exist directly beneath the coils 42A and 42D in either the surface layer (first layer) or the second layer.

[0097] In Figure 16, the second layer conductor 33 is not located directly beneath the coils 42B and 42C. Alternatively, the second layer conductor 33 may be located directly beneath the coils 42B and 42C. The substrate 30 has a ground wire 339 located in the third layer. The ground wire 339 is located over a wide area. The ground wire 339 is sometimes referred to as an inner layer ground or solid ground. In a plan view, the ground wire 339 is located so as to overlap the main body 421 of all coils 42. Conductors 33 that can function as non-jointed conductors 338 are not located in a layer closer to one surface 30a than the ground wire 339, directly beneath the coils 42A and 42D. The other configurations are the same as those described in the prior embodiment.

[0098] <Summary of the third embodiment> As illustrated, by placing the non-joint conductor 338 directly below the intermediate coil but not directly below the end coil, the area of ​​the non-joint conductor 338 located directly below one coil 42 may be smaller than that of the non-joint conductor directly below the intermediate coil. By eliminating the non-joint conductor 338 directly below the end coil, the absorption of magnetic flux by the non-joint conductor 338 can be further weakened, and the decrease in the inductance of the end coil can be suppressed. In other words, by not providing a non-joint conductor 338 directly below, the inductance of the end coil can be increased compared to a configuration in which a non-joint conductor 338 is provided. This makes it possible to reduce the difference in inductance between the intermediate coil and the end coil.

[0099] Furthermore, when the effect of the presence or absence of the non-joint conductor 338 on the inductance of one coil 42 was measured, the inductance increased by approximately 5.5% when the non-joint conductor 338 was not provided, compared to the configuration in which the non-joint conductor 338 overlapped the entire area of ​​the main body 421. Thus, it was confirmed that the decrease in inductance due to magnetic flux absorption can be suppressed by not providing the non-joint conductor 338.

[0100] As illustrated, in the layer where the lands 334 and 335 of the substrate 30 are located, the non-jointed conductor 338 is located directly beneath the intermediate coil, but not directly beneath the end coil. By placing the non-jointed conductor 338 on the layer where the lands 334 and 335 are located, i.e., the surface layer, the non-jointed conductor 338 is brought closer to the coil 42. Therefore, the absorption of magnetic flux by the non-jointed conductor 338 can be increased. In other words, the difference in inductance with and without the non-jointed conductor 338 can be made larger.

[0101] As illustrated, the non-jointed conductor 338 may be configured to be present in multiple layers directly below the end coil, continuous from the surface layer, for example, not present in the surface layer and the second layer. By not placing the non-jointed conductor 338 in layers deeper than the surface layer, the magnetic coupling between the end coil and the non-jointed conductor 338 can be further weakened. Therefore, the effect of reducing the difference in inductance between the intermediate coil and the end coil can be enhanced.

[0102] <Variation> An example of placing the non-jointed conductor 338 on the surface layer has been shown, but the invention is not limited to this. The non-jointed conductor 338 may not be placed on the surface layer, but for example, on the second layer. In the second layer, the non-jointed conductor 338 may be patterned so that it is located directly below coils 42B and 42C, but not directly below coils 42A and 42D.

[0103] A portion of the ground wiring 339 may be made into a non-jointed conductor 338. For example, the ground wiring 339 may be patterned so that it overlaps with coils 42B and 42C in a plan view, but does not overlap with coils 42A and 42D.

[0104] As shown in the prior embodiment, the non-jointed conductors 338 may be provided individually with respect to the coil 42. In the configuration shown in Figure 15, the non-jointed conductor 338 located directly below coil 42B and the non-jointed conductor 338 located directly below coil 42C may be separated.

[0105] (Fourth Embodiment) This embodiment is a modification based on the prior embodiment, and the description of the prior embodiment can be referenced. In the prior embodiment, non-jointed conductors were separated from the wiring constituting the circuit. Alternatively, a portion of the wiring that provides a predetermined potential may be made into a non-jointed conductor.

[0106] Figure 17 is a plan view showing the electronic device according to this embodiment. Figure 17 corresponds to Figure 3. In Figure 17, the coupled inductor is shown as transparent. The resist is omitted. For convenience, the cover is omitted in Figure 17. The outer casing of the core is shown by a dashed line, and the coil is shown by a dashed line.

[0107] The substrate 30, like the prior embodiment, has wiring 333 arranged on the surface layer on one side 30a. The wiring 333 extends generally in the Y direction. The wiring 333 electrically connects the ground terminal of the capacitor 60 to a ground terminal (not shown) of the switching device 50. The substrate 30 has five wirings 333.

[0108] Of the five wires 333, the wire 333 located between the branching points of wire 332 crosses the coupled inductor 40 in the Y direction. One of the wires 333 is positioned to overlap a portion of the lower wall 421b side of the main body 421 of coil 42A and a portion of the lower wall 421a side of the main body 421 of coil 42B. Another wire 333 is positioned to overlap a portion of the lower wall 421b side of the main body 421 of coil 42B and a portion of the lower wall 421a side of the main body 421 of coil 42C. Another wire 333 is positioned to overlap a portion of the lower wall 421b side of the main body 421 of coil 42C and a portion of the lower wall 421a side of the main body 421 of coil 42D. The three wires 333 crossing the coupled inductor 40 are interconnected at a position where they overlap the main body 421 of coil 42 in a plan view.

[0109] Of the three wires 333, the portion that overlaps with the main body 421 forms the non-jointed conductor 338. The non-jointed conductor 338 is arranged to overlap almost the entire main body 421 of coils 42B and 42C, and partially overlap the main body 421 of coils 42A and 42D, similar to the configuration shown in Figure 3. The other configurations are the same as those described in the prior embodiment.

[0110] <Summary of the fourth embodiment> As illustrated, a portion of the wiring that provides a predetermined potential on the substrate 30 may be a non-jointed conductor 338. In the illustrated electronic device 20, the wiring 333 corresponds to the wiring that provides a predetermined potential. Since the non-jointed conductor 338 is fixed at a predetermined potential, the non-jointed conductor 338 functions as an antenna, and the radiation of magnetic coupling components between the coil 42 and the non-jointed conductor 338 can be suppressed. In other words, radiated noise can be reduced. The same effect can be achieved when a portion of the ground wiring 339 is a non-jointed conductor 338, as shown in the prior embodiment.

[0111] As illustrated, a coupling inductor 40 may be placed between the switching device 50 and the capacitor 60 in an orthogonal direction perpendicular to both the thickness direction and the predetermined direction. In this arrangement, a portion of the ground wiring that electrically connects the capacitor 60 and the switching device 50 may be used as a non-jointed conductor 338. In the illustrated electronic device 20, the Z direction corresponds to the thickness direction, the X direction corresponds to the predetermined direction, the Y direction corresponds to the orthogonal direction, and the wiring 333 corresponds to the ground wiring.

[0112] In this configuration, the ground wiring is placed directly beneath the coupled inductor 40, and a portion of the ground wiring is used as a non-jointed conductor 338. This shortens the return path from the capacitor 60 to the switching device 50, thereby suppressing radiated noise. In particular, in the configuration shown in Figure 17, the capacitor 60 and the switching device 50 are electrically connected only by the wiring 333 located on the surface layer of one side 30a, further shortening the return path and effectively reducing radiated noise.

[0113] <Variation> The configuration in which a portion of the ground wiring electrically connecting the capacitor 60 and the switching device 50 is made of a non-jointed conductor 338 is not limited to the example described above. The inner layer wiring disposed inside the insulating substrate 31 may also be included as part of the ground wiring electrically connecting the capacitor 60 and the switching device 50. The inner layer wiring is connected to the surface layer wiring via via conductors.

[0114] An example of connecting multiple wires 333 has been shown, but the configuration is not limited to this. Alternatively, the three wires 333 crossing the coupled inductor 40 may not be connected. Furthermore, some of the multiple wires 333 crossing the coupled inductor 40 may be connected, while others remain unconnected. Connecting multiple wires 333 allows for the sharing of a return path.

[0115] As an example of wiring that provides a predetermined potential, an example of ground wiring that electrically connects the capacitor 60 and the switching device 50 has been shown, but the invention is not limited to this. Ground wiring provided separately from the ground wiring that electrically connects the capacitor 60 and the switching device 50 may also be used. The same effect can be achieved even when a part of the ground wiring 339 shown in the prior embodiment is made into a non-jointed conductor 338. The predetermined potential is not limited to the ground potential. For example, it may be the power supply potential.

[0116] (Fifth embodiment) This embodiment is a modification based on the prior embodiment, and the description of the prior embodiment can be referenced. In the prior embodiment, a portion of the ground wiring was made a non-jointed conductor. Alternatively, a non-jointed conductor may be provided so as to be connected to the land.

[0117] Figure 18 is a plan view showing the electronic device according to this embodiment. Figure 18 corresponds to Figure 3. In Figure 18, the coupled inductor is shown as transparent. The resist is omitted. For convenience, the cover is omitted in Figure 18. The outer casing of the core is shown by a dashed line, and the coil is shown by a dashed line.

[0118] In the example electronic device 20, the non-bonding conductor 338 is located on the surface layer on one side 30a and is connected to the land 334. The non-bonding conductor 338 is covered with resist 32. The substrate 30 has a non-bonding conductor 338 located directly beneath the coils 42B and 42C, similar to the configuration shown in Figure 15. The non-bonding conductor 338 is not located directly beneath the coils 42A and 42D.

[0119] The non-jointed conductors 338 are provided individually for each coil 42. The substrate 30 has two non-jointed conductors 338. The non-jointed conductor 338 located directly beneath coil 42B is connected to the land 334 to which coil 42B is joined. The non-jointed conductor 338 located directly beneath coil 42C is connected to the land 334 to which coil 42C is joined. The non-jointed conductors 338 cover almost the entire area of ​​the corresponding main body 421. The other configurations are the same as those described in the prior embodiment.

[0120] <Summary of the Fifth Embodiment> As illustrated, the conductor 33 connected to the land 334 may be a non-jointed conductor 338. In this configuration as well, the same effect as a non-jointed conductor 338 electrically isolated from the lands 334 and 335 can be achieved. For example, by making the area of ​​the non-jointed conductor 338 located directly below one coil 42 smaller than the area directly below the intermediate coil at the end coil, the difference in inductance between the end coil and the intermediate coil can be reduced.

[0121] <Variation> A non-jointed conductor 338 connected to land 334 may be provided directly below coils 42A and 42D.

[0122] The unjointed conductor 338 may be connected to either land 334 or 335. For example, conductor 33 connected to land 335 may be the unjointed conductor 338.

[0123] (Other embodiments) The disclosures in this specification and drawings are not limited to the exemplary embodiments. The disclosures include the exemplary embodiments and variations thereof by those skilled in the art. For example, the disclosures are not limited to combinations of parts and / or elements shown in the embodiments. The disclosures are implementable in a variety of combinations. The disclosures may have additional parts that can be added to the embodiments. The disclosures include those in which parts and / or elements of the embodiments have been omitted. The disclosures include substitutions or combinations of parts and / or elements between one embodiment and another. The scope of the disclosed technical areas is not limited to the descriptions of the embodiments. Some of the scope of the disclosed technical areas are indicated by the claims and should be understood to include all modifications within the meaning and scope equivalent to the claims.

[0124] The disclosures in the specification and drawings are not limited by the claims. The disclosures in the specification and drawings encompass the technical ideas described in the claims and extend to a wider and more diverse range of technical ideas than those described in the claims. Therefore, a variety of technical ideas can be extracted from the disclosures in the specification and drawings without being bound by the claims.

[0125] When an element or layer is referred to as “on top of,” “connected to,” “linked to,” or “joined,” it may be directly on top of, connected to, or joined to another element or layer, and there may also be an intervening element or layer. In contrast, when an element is referred to as “directly on top of,” “directly connected to,” “directly linked to,” or “directly joined to” another element or layer, there is no intervening element or layer. Other words used to describe relationships between elements should be interpreted in a similar manner (e.g., “between” vs. “directly between,” “adjacent” vs. “directly adjacent,” etc.). As used in this specification, the term “and / or” includes any combination and all combinations relating to one or more of the enumerated items relating to the element. A statement “A and / or B” includes A only, B only, or A and B. That is, a statement “A and / or B” means at least one of A and B.

[0126] Spatially relative terms such as "inside," "outside," "back," "below," "low," "above," and "high" are used here to facilitate descriptions of the relationship between one element or feature and other elements or features, as illustrated. Spatially relative terms may be intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the drawings. For example, if the device in the drawing is turned upside down, an element described as "below" or "directly below" another element or feature will be oriented "above" the other element or feature. Thus, the term "below" can encompass both up and down orientations. The device may also be oriented in other directions (it may be rotated 90 degrees or in other directions), and the spatially relative descriptors used in this specification will be interpreted accordingly.

[0127] (Disclosure of technical ideas) This specification discloses several technical concepts, as listed in the following paragraphs. Some paragraphs are written in a multiple dependent form, where subsequent paragraphs optionally refer to preceding paragraphs. Furthermore, some paragraphs are written in a multiple dependent form, referring to other multiple dependent forms. These paragraphs written in multiple dependent forms define several technical concepts.

[0128] <Technical philosophy 1> A substrate (30) having an insulating substrate (31) and a conductor (33) disposed on the insulating substrate, A coupled inductor (40) having a core (41) and a plurality of coils (42) arranged on the core, aligned in a predetermined direction perpendicular to the thickness direction of the substrate, and magnetically coupled to one another, Equipped with, The plurality of coils include end coils (42A, 42D) located at the ends in the predetermined direction, and intermediate coils (42B, 42C) located between the end coils. The coil has a main body portion (421) wound around the core and terminal portions (422, 423) connected to the main body portion. The conductor includes lands (334, 335) exposed on one surface of the substrate and joined to the terminal portion, and an unjointed conductor (338) provided in a position overlapping with the main body portion in a plan view in the thickness direction of the board and not joined to the coil. An electronic device in which the area of ​​the non-jointed conductor located directly below one of the coils is smaller directly below the end coil than the area directly below the intermediate coil.

[0129] <Technical philosophy 2> The non-jointed conductor is located directly below the end coil in the electronic device according to technical concept 1.

[0130] <Technical philosophy 3> The electronic device according to technical concept 2, wherein the non-jointed conductor is arranged to overlap with the main body portion of the end coil over its entire length in the predetermined direction.

[0131] <Technical philosophy 4> The core has a plurality of core portions (411) individually provided with respect to the coil and around which the corresponding main body portion of the coil is wound, a first end portion (412) to which one end of the plurality of core portions is connected, and a second end portion (413) arranged in an orthogonal direction perpendicular to both the thickness direction and the predetermined direction, sandwiching the plurality of core portions between itself and the first end portion, to which the other ends of the plurality of core portions are connected. The core portion is divided into multiple parts in the orthogonal direction and has gaps (411g) between them. The non-jointed conductor corresponding to the end coil is arranged so as to overlap with the gap in the plan view, as described in Technical Concept 2 or Technical Concept 3, for the electronic device.

[0132] <Technical philosophy 5> The electronic device according to technical concept 1, wherein the non-jointed conductor is located directly below the intermediate coil and not directly below the end coil.

[0133] <Technical philosophy 6> The electronic device according to technical concept 5, wherein in the layer on the substrate where the lands are arranged, the non-bonded conductor is located directly beneath the intermediate coil and not directly beneath the end coil.

[0134] <Technical philosophy 7> The non-jointed conductor is part of the wiring (333) that provides a predetermined potential on the substrate, as described in any one of technical ideas 1 to 6 of the electronic device.

[0135] <Technical philosophy 8> The board is mounted and comprises a switching device (50) and a capacitor (60) that, together with the coupling inductor, constitute a multiphase power supply. In an orthogonal direction perpendicular to both the plate thickness direction and the predetermined direction, the coupling inductor is arranged between the switching device and the capacitor. The aforementioned wiring is a ground wire that electrically connects the capacitor and the switching device, as described in Technical Concept 7 of the electronic device. [Explanation of symbols]

[0136] 10…ECU, 11…Primary power supply circuit, 12…Secondary power supply circuit, 121…Driver, 121H,121L…Switching element, 122…Coupled inductor, 122L…Inductor, 123…Capacitor, 13…Processor, 20…Electronic device, 30…Substrate, 30a…One side, 31…Insulating substrate, 32…Resist, 33…Conductor, 331,332,333…Wiring, 334,335,336,337…Land, 338…Non-bonded conductor, 3381…Wide section, 3382…Narrow section, 339…Ground wiring, 40…Coupled inductor, 41…Core, 411 ,4111,4112…core part, 411g…gap, 412,413…end part, 411a,412a,413a…top surface, 411b,412b,413b…bottom surface, 411c,411d,412c,412d,412e,412f,413c,413d,413e,413f…side, 42,42A,42B,42C,42D…coil, 421…main body part, 421a,421b…bottom wall, 421c,421d…side wall, 421e…top wall, 422,423…terminal part, 43…cover, 50…switching device, 60…capacitor, 70…solder

Claims

1. A substrate (30) having an insulating substrate (31) and a conductor (33) disposed on the insulating substrate, A coupled inductor (40) having a core (41) and a plurality of coils (42) arranged on the core, aligned in a predetermined direction perpendicular to the thickness direction of the substrate, and magnetically coupled to one another, Equipped with, The plurality of coils include end coils (42A, 42D) located at the ends in the predetermined direction, and intermediate coils (42B, 42C) located between the end coils. The coil has a main body portion (421) wound around the core and terminal portions (422, 423) connected to the main body portion. The conductor includes lands (334, 335) exposed on one surface of the substrate and joined to the terminal portion, and an unjointed conductor (338) provided in a position overlapping with the main body portion in a plan view in the thickness direction of the board and not joined to the coil. An electronic device in which the area of ​​the non-jointed conductor located directly below one of the coils is smaller directly below the end coil than the area directly below the intermediate coil.

2. The electronic device according to claim 1, wherein the non-jointed conductor is located directly below the end coil.

3. The electronic device according to claim 2, wherein the non-jointed conductor is arranged to overlap with the main body portion of the end coil over its entire length in the predetermined direction.

4. The core has a plurality of core portions (411) individually provided with respect to the coil and around which the corresponding main body portion of the coil is wound, a first end portion (412) to which one end of the plurality of core portions is connected, and a second end portion (413) arranged between the first end portion and the plurality of core portions in an orthogonal direction perpendicular to both the thickness direction and the predetermined direction, to which the other ends of the plurality of core portions are connected. The core portion is divided into multiple parts in the orthogonal direction and has gaps (411g) between them. The electronic device according to claim 3, wherein the non-jointed conductor corresponding to the end coil is arranged to overlap with the gap in the plan view.

5. The electronic device according to claim 1, wherein the non-jointed conductor is located directly below the intermediate coil and not directly below the end coil.

6. The electronic device according to claim 5, wherein in the layer on the substrate where the lands are arranged, the non-bonded conductor is located directly below the intermediate coil and not directly below the end coil.

7. The electronic device according to any one of claims 1 to 6, wherein the non-jointed conductor is part of the wiring (333) that provides a predetermined potential on the substrate.

8. The substrate is mounted and comprises a switching device (50) and a capacitor (60) that, together with the coupling inductor, constitute a multiphase power supply. In an orthogonal direction perpendicular to both the plate thickness direction and the predetermined direction, the coupling inductor is arranged between the switching device and the capacitor. The electronic device according to claim 7, wherein the wiring is a ground wire that electrically connects the capacitor and the switching device.

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