Electronic device

Abstract

To provide an electronic device capable of improving a solder life.SOLUTION: An electronic device 20 includes a substrate 30, a coupling inductor 40 having a core and a plurality of coils arranged on the core, and solder for joining the coils and lands. The plurality of coils are arranged in the X direction. The land bonded to the coil includes a plurality of mounting lands 331 provided corresponding to the coil and constituting a circuit together with the coil, and at least one stress relaxation land 332 provided at a position away from the mounting lands 331.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] TECHNICAL FIELD The disclosure herein relates to electronic devices. [Background technology]

[0002] Patent Document 1 discloses a coupled inductor. The contents of the prior art document are incorporated by reference as an explanation of the technical elements in this specification. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5698236 Summary of the Invention [Problem to be solved by the invention]

[0004] A coupled inductor includes a core and multiple coils arranged around the core and magnetically coupled to each other. In applications where a relatively large current flows, the coils are configured using metal plates rather than wires. For this reason, as shown in Patent Document 1, multiple coils are arranged side by side in a predetermined direction, and the size of the coupled inductor increases in the direction of the coil arrangement. When a coupled inductor is mounted on a substrate, the influence of substrate distortion acting on the solder joining the lands and coils on the substrate increases, which may shorten the solder life. Not limited to coupled inductors, but also in inductor components having multiple coils arranged side by side in a predetermined direction, the influence of substrate distortion acting on the solder joining the lands and coils may increase, which may shorten the solder life. Further improvements are desired in electronic devices in the above and other aspects not mentioned.

[0005] One of the objects of the present disclosure is to provide an electronic device that can improve solder life. [Means for solving the problem]

[0006] An electronic device according to one aspect of the disclosure includes: a substrate (30) having a plurality of lands (33); an inductor component (40) having a core (41) and a plurality of coils (42) arranged in the core; Solder (70) for joining the coil and the land; Equipped with The plurality of coils are arranged in a predetermined direction perpendicular to the thickness direction of the substrate, The lands joined to the coil include a plurality of mounting lands (331) that correspond to the coil and form a circuit together with the coil, and at least one stress relief land (332) that is located away from the mounting lands.

[0007] According to the disclosed electronic device, in addition to the mounting lands, stress relief lands are intentionally provided. The provision of stress relief lands increases the bonding points and bonding area of ​​the inductor component to the substrate. By adding stress relief lands, it is possible to use an inductor component with a configuration in which the coils are aligned in a predetermined direction, while also alleviating the stress acting on the solder due to substrate distortion, thereby improving the solder life.

[0008] The various aspects disclosed in this specification employ different technical means to achieve their respective objectives. The reference numerals in parentheses in the claims are intended to exemplarily indicate the corresponding parts of the embodiments described below, and are not intended to limit the technical scope. The objectives, features, and advantages disclosed in this specification will become more apparent by reference to the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a circuit diagram showing a multiphase power supply to which an electronic device according to a first embodiment is applied. [Figure 2] FIG. 1 illustrates an example of an ECU equipped with a multi-phase power supply. [Figure 3]FIG. 1 is a plan view illustrating an example of an electronic device. [Figure 4] FIG. 1 is a perspective view showing a coupled inductor. [Figure 5] FIG. 2 is a plan view of a coupled inductor as viewed from the top side. [Figure 6] FIG. 2 is a plan view of the coupled inductor as viewed from the bottom side. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. 6 is a cross-sectional view taken along line IX-IX in FIG. 5. [Figure 10] 10A and 10B are diagrams showing the positional relationship between terminal portions and lands; [Figure 11] FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. [Figure 12] FIG. 12 is a cross-sectional view taken along line XII-XII in FIG. [Figure 13] FIG. 10 is a diagram showing the influence of substrate distortion in a reference example. [Figure 14] FIG. 10 is a diagram showing the positional relationship between terminal portions and lands in a reference example. [Figure 15] 10A and 10B are diagrams illustrating the influence of parasitic inductance due to an extension portion in a reference example. [Figure 16] FIG. 10 is a diagram illustrating the influence of parasitic inductance due to a stress relaxation land. [Figure 17] FIG. [Figure 18] FIG. 10 is a cross-sectional view showing the periphery of a coupled inductor in an electronic device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments will be described with reference to the drawings. Note that in each embodiment, corresponding components are designated by the same reference numerals, and redundant description may be omitted. When only a portion of the configuration is described in each embodiment, the configuration of another embodiment previously described may be applied to the remaining portion of the configuration. Furthermore, in addition to the combinations of configurations explicitly stated in the description of each embodiment, configurations of several embodiments may be partially combined together even if not explicitly stated, provided that there is no particular problem with the combination.

[0011] (First embodiment) The electronic device according to this embodiment includes an inductor component, such as a coupled inductor, including multiple coils (inductors), as described below. Such an electronic device can be applied to various electronic circuits, such as power supply circuits and high-frequency circuits. For example, the electronic device can be used to reduce the size and cost of a configuration using multiple inductors. An example of application to a multiphase power supply will be described below.

[0012] <Multiphase power supply> 1 is a circuit diagram showing a multiphase power supply to which an electronic device according to this embodiment is applied. For convenience, part of the power supply circuit is shown in a simplified form in FIG.

[0013] The multiphase power supply 10 shown in Fig. 1 is a step-down DC-DC converter. The multiphase power supply 10 steps down an input voltage Vin to a predetermined voltage and outputs it as an output voltage Vout. The multiphase power supply 10 includes a plurality of power supply circuits 11 and a capacitor 12.

[0014] The power supply circuit 11 is a switching power supply circuit. The power supply circuit 11 may be referred to as a phase, stage, channel (Ch), etc. The number of power supply circuits 11 may be referred to as the number of phases, the number of stages, the number of channels, etc. The power supply circuit 11 includes switching elements 13H and 13L and an inductor 14. The switching elements 13H and 13L may be, for example, MOSFETs or IGBTs. The switching elements 13H and 13L may be bipolar transistors. MOSFET is an abbreviation for Metal Oxide Semiconductor Field Effect Transistor. IGBT is an abbreviation for Insulated Gate Bipolar Transistor.

[0015] The switching elements 13H and 13L are connected in series between a power supply line to which an input voltage Vin is input and a ground (GND) line, with the switching element 13H on the high side. One end of the inductor 14 is connected to the connection point (midpoint) of the switching elements 13H and 13L. The other end of the inductor 14 is connected to the output line.

[0016] The multiple power supply circuits 11 are connected in parallel to one another. The multiple power supply circuits 11 are arranged in parallel to one another with respect to a load (not shown) that supplies an output voltage Vout. In the multiple power supply circuits 11, the power supply lines are connected to one another. In the multiple power supply circuits 11, the output lines are connected to one another. By paralleling the multiple power supply circuits 11, it is possible to increase the output current from the multiphase power supply 10, i.e., the load current. The number of the multiple power supply circuits 11 is not particularly limited. The illustrated multiphase power supply 10 includes four power supply circuits 11 (for four phases).

[0017] The capacitor 12 is connected to the output line. The positive terminal of the capacitor 12 is connected to the output line. The negative terminal of the capacitor 12 is connected to ground. The capacitor 12 may be provided individually for each power supply circuit 11, or may be provided in common for multiple power supply circuits 11. In the illustrated multi-phase power supply 10, the capacitor 12 is provided individually for each power supply circuit 11.

[0018] The multi-phase power supply 10 includes a coupled inductor 14C. In the coupled inductor 14C, the coils constituting each inductor 14 are arranged on a common core. One coupled inductor 14C provides multiple inductors 14 constituting multiple power supply circuits 11. The multiple coils are wound around a common core. This allows magnetic fields between the phases to cancel each other out, reducing the effective inductance value.

[0019] The multiphase power supply 10 may include a power supply control circuit (not shown). The power supply control circuit performs voltage mode control, for example, by feedback of the output voltage Vout, to control the operation of the switching elements 13H and 13L. In voltage mode control, the pulse width (duty ratio) of a PWM signal is determined based on the output voltage Vout, and the output voltage Vout of the multiphase power supply 10 is controlled. Note that current mode control may be performed instead of voltage mode control.

[0020] The power supply control circuit synchronously controls the multiple power supply circuits 11 so that they perform switching operations at different phases. By using multiple phases in this way, it is possible to increase the switching frequency artificially even if the switching frequency is the same for the multiple power supply circuits 11. This makes it possible to reduce output voltage ripple and improve responsiveness. The power supply control circuit switches the power supply circuits 11 to perform switching operations, i.e., the number of drive phases, depending on the load current. The power supply control circuit compares the load current with a threshold current and increases and / or decreases the number of drive phases depending on the comparison result.

[0021] FIG. 2 shows an application example of a multiphase power supply. The above-described multiphase power supply 10 is applied to, for example, an ECU 15. ECU is an abbreviation for Electronic Control Unit. The ECU 15 includes the multiphase power supply 10 and a control unit 16. The ECU 15 may be mounted on, for example, a mobile object. The mobile object may be, for example, a vehicle, an aircraft, a ship, construction machinery, agricultural machinery, or the like. The mobile object may be a manned mobile object or an unmanned mobile object.

[0022] The illustrated ECU 15 is mounted on a vehicle. The ECU 15 may be, for example, an autonomous driving ECU or an ADAS ECU that executes control to assist the driver in driving operations. ADAS is an abbreviation for Advanced Driving Assistant System. For example, levels 3 to 5 defined by the Society of Automotive Engineers International (SAE International) correspond to autonomous driving levels, and levels 1 and 2 correspond to driving assistance levels. The ECU 15 may be an infotainment ECU or a cockpit ECU. The cockpit ECU is an ECU that controls a meter device, a navigation device, an air conditioning device, etc.

[0023] The multi-phase power supply 10 supplies power to the control unit 16. The control unit 16 operates upon receiving the power supply. The illustrated control unit 16 includes a processor 17 and a memory (not shown). The processor is, for example, a CPU or a GPU. The CPU is an abbreviation for Central Processing Unit. The GPU is an abbreviation for Graphics Processing Unit. The control unit 16 may be realized by combining multiple types of arithmetic processing devices, such as a CPU and a GPU. The processor 17 executes a control program stored in the memory to perform predetermined processing for control.

[0024] The core voltage of the processor 17 is around 1 V (e.g., less than 1 V), and the load current is several tens of amperes or more (e.g., 100 A or more). To accommodate such low voltages and large currents, the ECU 15 employs a multi-phase power supply 10 as a power supply circuit. The multi-phase power supply 10 steps down the input voltage Vin to a voltage corresponding to the core voltage of the processor 17 and outputs the voltage as an output voltage Vout. The use of the multi-phase power supply 10 allows for increased performance of the processor 17 in line with improvements in autonomous driving levels and advances in infotainment functions, particularly for autonomous driving levels 3 and above.

[0025] In a high-performance processor 17, the current consumption fluctuates rapidly in response to the calculation processing, so a large number of capacitors 12 are required to supply a stable voltage even when the load suddenly changes. By using the coupled inductor 14C, the magnetic fields between the phases are canceled out as described above, and the effective inductance value can be reduced, improving responsiveness when the load suddenly changes. Therefore, compared to a configuration using a normal single inductor, the number of capacitors 12 can be significantly reduced. For example, the physical size of the ECU 15 can be reduced.

[0026] <General configuration of electronic device> Fig. 3 is a plan view showing an example of an electronic device. Fig. 3 is an enlarged view of the periphery of a coupled inductor in the electronic device. For convenience, the solder resist is omitted in Fig. 3. Furthermore, lands other than those corresponding to the coupled inductor are omitted.

[0027] The electronic device 20 includes a substrate 30 and a plurality of components mounted on the substrate 30. The plurality of components include a coupled inductor 40, a switching device 50, and a capacitor 60. The electronic device 20 provides the multi-phase power supply 10 described above. The electronic device 20 may also provide an ECU 15. In this case, a processor 17 is also mounted on the substrate 30.

[0028] In the following, the thickness direction of the substrate is referred to as the Z direction. The direction perpendicular to the Z direction, in which multiple coils are arranged, is referred to as the X direction. The direction perpendicular to both the Z direction and the X direction 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 planar view from the Z direction is sometimes simply referred to as the planar view.

[0029] The substrate 30 may be referred to as a printed circuit board, a printed wiring board, a wiring board, or the like. The substrate 30 has an insulating substrate 31 and a conductor 32. The insulating substrate 31 is formed using an electrically insulating material such as resin. The conductor 32 is disposed on the insulating substrate 31. At least a portion of the conductor 32, together with components mounted on the substrate 30, forms a circuit.

[0030] The conductor 32 has a land 33 and a wiring 34. The land 33, which corresponds to the coupled inductor 40, includes a mounting land 331 disposed on the surface layer of the insulating base material 31 and providing a wiring function. The mounting land 331 is disposed on the surface layer on one surface 30a of the substrate 30. The mounting land 331 includes mounting lands 3311 and 3312. The mounting land 3311 is provided at a position separated from the mounting land 3312 in the Y direction. The exemplary mounting land 331 is provided at the end of the wiring 34. The conductor 32 may have a via conductor. The via conductor is formed by disposing a conductor such as plating in a through hole (via) formed in an insulating layer that constitutes the insulating base material 31. The via conductor electrically connects the wiring 34 on different layers.

[0031] The wiring 34 is formed, for example, by patterning a metal foil. The wiring 34 is arranged on the surface layer of at least the first surface 30a. The wiring 34 may be arranged on the surface layer of the back surface in addition to the surface layer of the first surface 30a, or may be arranged inside the insulating base material 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 wiring 34 includes wirings 341, 342, 343, and 344.

[0032] The wiring 341 electrically connects the inductor 401 (coil 42) and the switching device 50. The wiring 341 is provided for each inductor 401. The mounting land 331 is provided at one end of the wiring 341. The wiring 341 extends in the Y direction. The multiple wirings 341 are lined up in the X direction.

[0033] The wiring 342 electrically connects the inductor 401 (coil 42) and the capacitor 60. The wiring 342 is provided for each inductor 401. The wiring 342 extends in the Y direction. The multiple wirings 342 are lined up in the X direction. The wiring 342 is provided at a position separated from the wiring 341 in the Y direction. The coupled inductor 40 is located between the wiring 342 and the wiring 341 in the Y direction.

[0034] The wiring 343 electrically connects the inductor 401 and the capacitor 60 to the output terminal of the multi-phase power supply. The wiring 343 is connected to the multiple wirings 342. The wiring 343 is a common wiring for the multiple wirings 342. The multiple wirings 342 are connected to the wiring 343. The wiring 344 is a ground wiring. The wiring 344 is electrically connected to a ground wiring in an inner layer, for example, via a via conductor (not shown). The wiring 344 is arranged between adjacent wirings 342. The wirings 344 and the wirings 343 are arranged alternately in the X direction. The wiring 34 includes three wirings 344. Details of the land structure corresponding to the coupled inductor 40 will be described later.

[0035] The coupled inductor 40 is disposed on one surface 30a of the substrate 30. The coupled inductor 40 provides the above-mentioned coupled inductor 14C. The coupled inductor 40 is an inductor component including a core 41 and a plurality of coils 42. The illustrated coupled inductor 40 includes four coils 42. The plurality of coils 42 are aligned in the X direction. The coupled inductor 40 includes a plurality of inductors 401. One end of the coil 42 is solder-bonded to a mounting land 3311, and the other end of the coil 42 is solder-bonded to a mounting land 3312. The structure of the coupled inductor 40 will be described in detail later.

[0036] The switching device 50 provides the above-mentioned switching elements 13H, 13L. The switching device 50 is provided corresponding to the coil 42, i.e., the inductor 401. The illustrated switching device 50 constitutes the switching elements 13H, 13L for one phase. One switching device 50 constitutes a driver for one phase. Alternatively, a switching device 50 may be provided for each of the switching elements 13H, 13L. The multiple switching devices 50 are aligned in the X direction. The switching devices 50 and the coupled inductor 40 are aligned in the Y direction. The switching device 50 is solder-joined to the end of the wiring 341 on the switching device 50 side.

[0037] The capacitor 60 provides the above-mentioned capacitor 12. A plurality of exemplary capacitors 60 are provided for each inductor 401. The capacitors 60 are, for example, chip capacitors. The capacitors 60 corresponding to each inductor 401 are lined up in the X direction. In the Y direction, the coupled inductor 40 is disposed between the switching device 50 and the capacitor 60. One terminal of the capacitor 60 is solder-bonded to the wiring 342, and the other terminal is solder-bonded to the wiring 344.

[0038] <Coupled inductor> Fig. 4 is a perspective view showing a coupled inductor. Fig. 5 is a plan view of the coupled inductor seen from above. Fig. 6 is a plan view of the coupled inductor seen from below. Fig. 7 is a perspective view showing a core. Fig. 8 is a perspective view showing a coil. Fig. 9 is a cross-sectional view taken along line IX-IX in Fig. 5.

[0039] As described above, one coupled inductor 40 provides multiple inductors 401. The coupled inductor 40 includes a core 41 and multiple coils 42. The coils 42 are arranged on one core 41, i.e., a common core 41, and are magnetically coupled to each other. By using the coupled inductor 40, magnetic fluxes between phases can be canceled out, thereby reducing the effective inductance.

[0040] 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 cores 411 and end cores 412 and 413. The coil 42 is inserted through the core 41. The core cores 411 are provided individually for the coils 42. The coils 42 are wound around the core cores 411. The core cores 411 extend in the Y direction. The plurality of core cores 411 are lined up in the X direction at predetermined intervals. The illustrated core 41 has four core cores 411. Each core core 411 is substantially rectangular parallelepiped-shaped. The four core cores 411 have the same shape.

[0041] The core core 411 may be a single component, or may be made up of multiple components. The illustrated core core 411 is divided at the center in the Y direction. The core core 411 includes a core core 4111 and a core core 4112. The core core 4111 is connected to the end core 412. The core core 4111 extends from a side surface 412e of the end core 412 toward the end core 413. The core core 4112 is connected to the end core 413. The core core 4112 extends from a side surface 413e of the end core 413 toward the end core 412. The core cores 4111 and 4112 are fixed, for example by adhesive, with their tips facing each other. The core cores 4111 and 4112 form a single core core 411.

[0042] The dividing position is not limited to the center. A single core 411 may be connected to one of the end cores 412, 413 and bonded to the other. Both ends of the single core 411 may be bonded to the end cores 412, 413, respectively.

[0043] The end core 412 and the end core 413 are arranged opposite to each other in the Y direction. The end cores 412, 413 sandwich the core core 411 between them. The end cores 412, 413 extend in the X direction, which is the arrangement direction of the multiple core cores 411. One ends of the multiple core cores 411 are connected to the end core 412, and the other ends of the multiple core cores 411 are connected to the end core 413. The end cores 412, 413 magnetically connect the multiple core cores 411. The illustrated end cores 412, 413 have the same shape. The end cores 412, 413 are substantially rectangular parallelepipeds with the X direction as their longitudinal direction.

[0044] The end core 412 has an upper surface 412a, a lower surface 412b, and side surfaces 412c, 412d, 412e, and 412f. The end core 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 surfaces facing the substrate 30 in the Z direction. The upper surfaces 412a and 413a are surfaces opposite the lower surfaces 412b and 413b in the Z direction. The side surfaces 412c and 413c are surfaces opposite the side surfaces 412d and 413d in the X direction. The side surfaces 412e and 413e face each other in the Y direction. The side surfaces 412f and 413f are surfaces opposite the side surfaces 412e and 413e in the Y direction.

[0045] The coil 42 is formed using a metal material with good conductivity, such as copper. The coil 42 is formed by processing a metal plate material, rather than a metal wire material. The metal plate material is sometimes called a metal frame. The multiple coils 42 are formed using the same material and have the same shape. The multiple coils 42 have approximately the same inductance. The multiple coils 42 are lined up in the X direction at a predetermined interval. The multiple coils 42 are lined up in the same direction. The coils 42 are fixed to the core 41, for example, by adhesive.

[0046] The coil 42 is formed by bending a metal plate having a predetermined thickness. The coil 42 has terminal portions 421, 422, side wall portions 423, 424, and an upper wall portion 425. The terminal portions 421, 422 are external connection terminals of the coil 42 and are soldered to the corresponding lands 33. The thickness direction of the terminal portions 421, 422 is approximately parallel to the Z direction, and the plate surfaces (lower surfaces) of the terminal portions 421, 422 face one surface 30a of the substrate 30. The terminal portions 421, 422 extend in the Y direction. The illustrated terminal portions 421, 422 have a substantially rectangular planar shape with the Y direction as the longitudinal direction. The terminal portions 421, 422 are aligned in the X direction at a predetermined interval. A portion of the side surface of the terminal portion 421 faces a portion of the side surface of the terminal portion 422 in the X direction. Terminal portion 421 extends in the Y direction from a portion facing terminal portion 422 to side surface 412f, i.e., toward switching device 50. Terminal portion 422 extends in the Y direction from a portion facing terminal portion 421 to side surface 413f, i.e., toward capacitor 60.

[0047] The side wall portion 423 is continuous with a portion of the terminal portion 421 that faces the terminal portion 422. The side wall portion 423 is bent so as to form an angle of approximately 90 degrees with respect to the terminal portion 421. The thickness direction of the side wall portion 423 is approximately parallel to the X direction. The side wall portion 423 has a width equal to the length of the portions of the terminal portions 421 and 422 that face each other, and extends in the Z direction. Similarly, the side wall portion 424 is continuous with a portion of the terminal portion 422 that faces the terminal portion 421. The side wall portion 424 is bent so as to form an angle of approximately 90 degrees with respect to the terminal portion 422. The thickness direction of the side wall portion 424 is approximately parallel to the X direction. The side wall portion 424 has a width equal to the length of the portions of the terminal portions 421 and 422 that face each other, and extends in the Z direction, the same direction as the side wall portion 423. The lower ends of the side walls 423 and 424 are connected to the terminals 421 and 422 .

[0048] The upper wall portion 425 bridges the side wall portions 423, 424. The upper wall portion 425 extends in the X direction. One end of the upper wall portion 425 is continuous with the upper end of the side wall portion 423, and the other end is continuous with the upper end of the side wall portion 424. The upper wall portion 425 has the same width as the side wall portions 423, 424. In a plan view, the upper wall portion 425 encompasses the entire area of ​​the opposing portions of the side wall portions 423, 424 and the terminal portions 421, 422.

[0049] The facing portions of the terminal portions 421, 422, the side walls 423, 424, and the upper wall 425 surround the core 411. The facing portions of the terminal portions 421, 422, the side walls 423, 424, and the upper wall 425 are attached to and wound around the core core 411. End cores 412, 413 are disposed in the portions excluding the facing portions of the terminal portions 421, 422, i.e., the extended portions. The lower surfaces 412b, 413b of the end cores 412, 413 may be positioned higher than the plate surfaces (upper surfaces) of the terminal portions 421, 422. The lower surfaces 412b, 413b may be provided with recesses in the lower surfaces 412b, 413b to accommodate the extended portions of the terminal portions 421, 422, so that the positions of the lower surfaces 412b, 413b are approximately flush with the lower surfaces of the terminal portions 421, 422.

[0050] In adjacent coils 42, one side wall portion 423 of the coil 42 faces the other side wall portion 424 of the coil 42. In the illustrated coupled inductor 40, the outer surface of the side wall portion 423 of the coil 42 located at one end is substantially flush with the side surfaces 412c and 413c. The outer surface of the side wall portion 424 of the coil 42 located at the other end is substantially flush with the side surfaces 412d and 413d. However, the position of the outer surface of the side wall portion 423 may be shifted with respect to the side surfaces 412c and 413c. Similarly, the position of the outer surface of the side wall portion 424 may be shifted with respect to the side surfaces 412d and 413d. In the illustrated coupled inductor 40, the upper surface of the upper wall portion 425 of the coil 42 is substantially flush with the upper surfaces 412a and 413a. However, the position of the upper surface of the upper wall portion 425 may be shifted with respect to the upper surfaces 412a and 413a.

[0051] <Connection structure between coupled inductor and substrate> FIG. 10 is a diagram showing the positional relationship between the terminal portion of the coil and the lands of the substrate. FIG. 10 corresponds to FIG. 3. However, the outline of the coupled inductor is shown by a dashed dotted line. Only the terminal portion of the coil is shown. The lands that overlap with the coupled inductor in a plan view are also shown by solid lines. FIG. 11 is a cross-sectional view taken along line XI-XI of FIG. 10. FIG. 12 is a cross-sectional view taken along line XII-XII of FIG. 10. For convenience, only the mounting lands of the conductors of the substrate are shown in FIGS. 11 and 12. The solder resist is omitted from FIGS. 10 to 12.

[0052] As described above, the land 33 has a plurality of mounting lands 331 as lands 33 corresponding to the coupled inductor 40. The mounting lands 331 form a circuit together with the coil 42. The mounting lands 331 include mounting lands 3311 corresponding to the terminal portions 421 and mounting lands 3312 corresponding to the terminal portions 422. The mounting lands 331 include the same number of mounting lands 3311 as the terminal portions 421, and the same number of mounting lands 3312 as the terminal portions 422. The illustrated mounting lands 331 include four mounting lands 3311 and four mounting lands 3312. The numbers of mounting lands 3311 and 3312 are equal to each other.

[0053] The four mounting lands 3311 are lined up in the X direction at a predetermined interval. The four mounting lands 3312 are lined up in the X direction at a predetermined interval. The mounting lands 3312 are provided so as to be shifted in the X direction relative to the mounting lands 3311. The mounting lands 3311 and 3312 are arranged in a staggered pattern. Of the eight mounting lands 3311 and 3312 lined up in the X direction, one terminal portion 421 is arranged at one end and one terminal portion 422 is arranged at the other end.

[0054] The mounting land 3311 is provided so as to overlap a portion of the terminal portion 421 in a plan view. At least a portion of the mounting land 3311 is located directly below the terminal portion 421. The mounting land 3312 is provided so as to overlap a portion of the terminal portion 422 in a plan view. At least a portion of the mounting land 3312 is located directly below the terminal portion 422. The illustrated mounting land 3311 is provided so as to overlap a portion within a predetermined range from the end of the terminal portion 421 on the side surface 412f side. The mounting land 3312 is provided so as to overlap a portion within a predetermined range from the end of the terminal portion 422 on the side surface 412f side.

[0055] The substrate 30 has at least one stress relief land 332 as the land 33 corresponding to the coupled inductor 40. The stress relief land 332 relieves stress acting on the solder joint of the mounting land 331. The stress relief land 332 may provide a wiring function. The stress relief land 332 may be electrically connected to the inner layer wiring 34, for example, through a via conductor. The stress relief land 332 may not provide a wiring function. In other words, the stress relief land 332 may be configured not to be connected to other conductors 32. The illustrated stress relief land 332 does not provide a wiring function.

[0056] The stress relaxation land 332 is disposed on the surface layer on the one surface 30a side of the substrate 30. The stress relaxation land 332 is provided at a position separated from the mounting land 331 in a plan view. The illustrated stress relaxation land 332 is provided between the mounting land 3311 and the mounting land 3312 in the Y direction, for example, near the midpoint between the mounting land 3311 and the mounting land 3312.

[0057] One stress relaxation land 332 may be bonded to one of the terminal portions 421, 422, or may be bonded to the terminal portions 421, 422 that form the common coil 42. The stress relaxation land 332 is provided so as to overlap a portion of the corresponding terminal portion 421, 422 in a plan view. At least a portion of the stress relaxation land 332 is located directly below the corresponding terminal portion 421, 422. The illustrated substrate 30 has two stress relaxation lands 332. The stress relaxation lands 332 are provided directly below the terminal portions 421, 422 at both ends in the X direction. One of the stress relaxation lands 332 is located directly below the terminal portion 421 located at the end on the side surfaces 412c and 413c sides. The other stress relaxation land 332 is located directly below the terminal portion 422 located at the end on the side surfaces 412d and 413d sides.

[0058] The planar shape and size of the stress relaxation lands 332 are not particularly limited. The size is the area in a plan view. In the illustrated substrate 30, the mounting lands 311 and the stress relaxation lands 332 have a generally rectangular planar shape with the X direction as the longitudinal direction. The size of one stress relaxation land 332 is smaller than the size of one mounting land 331. In the Y direction, the length L2 of one stress relaxation land 332 is longer than the length L1 of one mounting land 331.

[0059] The terminal portion 421 is joined to the corresponding mounting land 3311 via solder 70. The terminal portion 422 is joined to the corresponding mounting land 3312 via solder 70. The terminal portion 421 located at the end on the side surfaces 412c and 413c side in the X direction is joined to the stress relief land 332 via solder 70. The terminal portion 421 located at the end on the side surfaces 412c and 413c side is joined to the mounting land 3311 and the stress relief land 332. The terminal portion 422 located at the end on the side surfaces 412d and 413d side in the X direction is joined to the stress relief land 332 via solder 70. The terminal portion 422 located at the end on the side surfaces 412d and 413d side is joined to the mounting land 3312 and the stress relief land 332.

[0060] In the connection structure between the substrate 30 and the coupled inductor 40 described above, current flows through the wiring 341, the mounting land 3311, the terminal portion 421, the side wall portion 423, the upper wall portion 425, the side wall portion 424, the terminal portion 422, the mounting land 3312, and the wiring 342 in this order.

[0061] <Summary of the First Embodiment> Fig. 13 is a diagram showing the influence of board distortion in a reference example. Fig. 13 corresponds to Fig. 11. Fig. 13 is a simplified version of Fig. 11. In Fig. 13, the stress acting on the solder is indicated by solid arrows. In the reference example, R is added to the symbol for the electronic device.

[0062] 13, the substrate 30 differs from the electronic device 20 shown in this embodiment in that it only has mounting lands 331 as lands 33 corresponding to the coupled inductor 40. The coupled inductor 40 has the same configuration as the electronic device 20 shown in this embodiment. The coupled inductor 40 has four coils 42 (not shown) aligned in the X direction. As the number of coils 42 increases, the length of the coupled inductor 40 in the X direction increases.

[0063] For example, in the ZX plane, if board distortion (warping) occurs such that the board edge moves away from the center of the board where the coupled inductor 40 is mounted, stress due to the board distortion acts on the solder 70. The stress acting on the solder 70 is greater the closer it is to the edge of the coupled inductor 40. This reduces the connection reliability of the solder 70 near the edge.

[0064] The electronic device 20 of this embodiment includes a substrate 30, a coupled inductor 40, and solder 70. A plurality of coils 42 are arranged in a predetermined direction (X direction) perpendicular to the thickness direction (Z direction) of the substrate 30. The lands 33 solder-joined to the coils 42 are provided corresponding to the coils 42 and include a plurality of mounting lands 331 that form a circuit together with the coils 42, and at least one stress relief land 332 provided at a position separated from the mounting land 331. The coupled inductor 40 corresponds to an inductor component having a core 41 and a plurality of coils 42 arranged on the core 41.

[0065] In this way, stress relief lands 332 are intentionally provided in addition to mounting lands 331. By providing stress relief lands 332, the number of joining locations and joining area of ​​coupled inductor 40 to substrate 30 increases. The amount of solder 70 joining substrate 30 and coupled inductor 40 increases. By adding stress relief lands 332, it is possible to employ coupled inductor 40 (inductor component) configured with coils 42 aligned in a predetermined direction, while also easing stress due to substrate distortion and improving solder life.

[0066] The stress relief land 332 may be provided directly below any one of the multiple coils 42 included in the coupled inductor 40. The stress relief land 332 may be provided, for example, directly below a coil 42 located near the center of the coupled inductor 40 in a predetermined direction. As illustrated, the stress relief land 332 may be provided directly below a coil 42 located closer to the end of the coupled inductor than the center of the coupled inductor in a predetermined direction. Since the solder 70 on the mounting land 331 closer to the end is subjected to greater stress due to board distortion, providing the stress relief land 332 near the end can further improve the solder life.

[0067] As shown in the example, the stress relaxation land 332 may be provided directly below the coil located at the end of the coils in a predetermined direction. The stress relaxation land 332 may also be provided directly below the terminal portions 421, 422 located at both ends in the predetermined direction. Since the mounting land 331, which is subject to the greatest stress due to board distortion, and the stress relaxation land 332 are joined to the same object, the solder life can be further improved.

[0068] As shown in the example, the stress relief land 332 may be provided between the first mounting land and the second mounting land in the direction (Y direction) perpendicular to both the plate thickness direction and the predetermined direction. One of the mounting lands 3311 and 3312 corresponds to the first mounting land, and the other corresponds to the second mounting land. By providing the stress relief land 332 between the mounting lands 3311 and 3312 in the Y direction, stress can be relieved for both the solder 70 on the mounting land 3311 and the solder 70 on the mounting land 3312, thereby improving the solder life.

[0069] FIG. 14 is a diagram showing the positional relationship between terminal portions and lands in another reference example. FIG. 14 corresponds to FIG. 10. In the electronic device 20R2 shown in FIG. 14, mounting lands 3311 and 3312 are extended relative to the electronic device 20R1 to improve connection reliability at the end portions. The mounting lands 3311 and 3312 located at both ends in the X direction have extensions 333. The extensions 333 extend further than the other mounting lands 3311 and 3312, and the boundaries of the extensions 333 are indicated by dashed lines. The extensions 333 are larger than the mounting lands 3311 and 3312 that do not have extensions 333. In this way, by increasing the area of ​​the mounting lands 3311 and 3312 at the end portions where stress is high, it is possible to improve the connection reliability of the solder 70.

[0070] 15 is a diagram showing the influence of parasitic inductance due to the extension in the reference example shown in FIG. 14. Here, when the extension 333 is not provided, the inductance on the mounting land 3311 side up to the position of the extension 333 is defined as Lk1, and the inductance on the mounting land 3312 side is defined as Lk2. The parasitic inductance due to the extension 333 is defined as Lland. The parasitic inductance Lland is connected in parallel to the inductance Lk1. When the extension 333 is not provided, the inductance Lk between the mounting lands 3311 and 3312 via the coil 42 is the sum of the inductances Lk1 and Lk2. The inductance Lk when the extension 333 is provided is expressed by Equation 1. Lk=(Lk1 / / Lland)+Lk2 <Lk1+Lk2···(1)

[0071] The reciprocal of the first term (Lk1 / / Lland) on the right side of Equation 1 is equal to the sum of the reciprocal of Lk1 and the reciprocal of Lland. The first term on the right side is smaller than the inductance Lk1. In other words, providing the extension 333 reduces the inductance Lk, making it impossible to obtain the desired power supply characteristics.

[0072] As shown in the example, the stress relaxation lands 332 may be configured not to provide a wiring function on the substrate 30. Compared to a configuration in which the stress relaxation lands 332 are electrically connected to the mounting lands 331 on the substrate 30, the effect of the parasitic inductance of the stress relaxation lands 332 on the inductance Lk can be reduced.

[0073] As shown in the example, the stress relaxation lands 332 may be smaller than the mounting lands 331 in plan view. Since the area of ​​one stress relaxation land 332 is smaller than the area of ​​one mounting land 331, the parasitic inductance of the stress relaxation lands 332 can be reduced. This makes it possible to suppress fluctuations in inductance Lk due to the parasitic inductance of the stress relaxation lands 332.

[0074] As shown in the example, the length L2 of the stress relaxation land 332 in the Y direction may be shorter than the length L1 of the mounting land 331. This reduces the parasitic inductance of the stress relaxation land 332 in the direction of current flow, thereby effectively suppressing fluctuations in inductance Lk.

[0075] FIG. 16 is a diagram showing the effect of parasitic inductance due to stress relaxation lands in the electronic device 20. In this electronic device 20, as shown in FIG. 10, the length L2 of the stress relaxation lands 332 is made sufficiently shorter than the length L1 of the mounting lands 331. The length L2 is, for example, equal to or less than half the length L1. This makes it possible to almost completely ignore the effect of the parasitic inductance Lland of the stress relaxation lands 332. The inductance Lk when such stress relaxation lands 332 are provided is expressed by Equation 2. As shown in Equation 2, the reduction in inductance Lk due to the addition of the stress relaxation lands 332 can be effectively suppressed. Lk ≒ Lk1 + Lk2 (2)

[0076] As illustrated, the electronic device 20 may be mounted on a substrate 30 and include a plurality of switching devices 50 and capacitors 60 that, together with the coupled inductor 40, constitute the multiphase power supply 10. The coupled inductor 40 may be disposed between the switching devices 50 and the capacitors 60 in the Y direction. In a configuration in which the plurality of coils 42 of the coupled inductor 40 are aligned in the X direction, the switching devices 50, the coupled inductors 40, and the capacitors 60 are aligned in the Y direction, which simplifies wiring and prevents the device from becoming too large.

[0077] <Modification> Although an example has been shown in which the stress relaxation land 332 is provided between the mounting land 3311 and the mounting land 3312 in the Y direction, this is not limiting. For example, as shown in FIG. 17 , a notch 334 may be provided in the mounting land 331, and the stress relaxation land 332 may be provided in the notch 334. In FIG. 17 , the notch 334 is provided at the end of the mounting land 3311 on the wiring 341 side. Similarly, the notch 334 is provided at the end of the mounting land 3312 on the wiring 342 side. FIG. 17 corresponds to FIG. 10 .

[0078] (Second embodiment) This embodiment is a modification based on the previous embodiment, and the description of the previous embodiment can be used. In the previous embodiment, the lower surface of the terminal portion is flat. Instead, a recess may be provided on the lower surface of the terminal portion.

[0079] Fig. 18 is a cross-sectional view showing the periphery of the coupled inductor in the electronic device according to this embodiment. Fig. 18 corresponds to Fig. 12. As shown in Fig. 18, terminal portions 421 and 422 located at both ends in the X direction have recesses 426 on their lower surfaces. In Fig. 18, recesses 426 are provided in terminal portion 421 located at the end on the side of side surfaces 412c and 413c. Although not shown, recesses 426 are also provided in terminal portion 422 located at the end on the side of side surfaces 412d and 413d.

[0080] The recess 426 is provided at a position facing the stress relief land 332. The recess 426 is provided at a position overlapping the stress relief land 332 in a plan view. The solder 70 that joins the coil 42 and the stress relief land 332 is disposed in the recess 426. The solder 70 is filled into the recess 426 and is in contact with the bottom and side surfaces of the recess 426. The other configurations are the same as those described in the preceding embodiment.

[0081] <Summary of the second embodiment> As illustrated, the coil 42 may have a recess 426 at a position facing the stress relief land 332. The terminal portions 421, 422 of the coil 42 may have a recess 426 at a position facing the stress relief land 332. The solder 70 that joins the coil 42 and the stress relief land 332 may be disposed in the recess 426. This increases the contact area (joining area) between the solder 70 and the coil 42. This further improves the solder life.

[0082] (Other embodiments) The disclosure in this specification and drawings, etc. is not limited to the exemplified embodiments. The disclosure encompasses the exemplified embodiments and modifications thereto by those skilled in the art. For example, the disclosure is not limited to the combinations of parts and / or elements shown in the embodiments. The disclosure can be implemented in various combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure encompasses the omission of parts and / or elements from the embodiments. The disclosure encompasses the substitution or combination of parts and / or elements between one embodiment and another embodiment. The disclosed technical scope is not limited to the description of the embodiments. Some disclosed technical scopes are defined by the claims, and should be interpreted as including all modifications within the meaning and scope equivalent to the claims.

[0083] The disclosure in the specification, drawings, etc. is not limited by the claims. The disclosure in the specification, drawings, etc. encompasses the technical ideas described in the claims, and extends to more diverse and broader technical ideas than the technical ideas described in the claims. Therefore, various technical ideas can be extracted from the disclosure in the specification, drawings, etc. without being bound by the claims.

[0084] When an element or layer is referred to as being "on," "coupled," "connected," or "bonded," it may be directly on, coupled, connected, or bonded to another element or layer, and intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly coupled," "directly connected," or "directly bonded" to another element or layer, no intervening elements or layers are present. Other terms used to describe relationships between elements should be construed 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 and all combinations of one or more of the associated listed items. That is, reference to A and / or B means at least one of A and B.

[0085] Spatially relative terms such as "inside," "outside," "back," "below," "low," "top," "top," and the like are used herein to facilitate the description of one element or feature's relationship to other elements or features, as illustrated. Spatially relative terms may be intended to encompass different orientations of the device during use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures were turned over, elements described as "below" or "directly below" other elements or features would then be oriented "above" the other elements or features. Thus, the term "bottom" can encompass both an orientation of top and bottom. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used in this specification would be interpreted accordingly.

[0086] Although the coupled inductor 40 has been shown as an example of an inductor component, the present invention is not limited to this. The inductor component is not limited to a configuration in which multiple coils 42 are arranged on a common core 41 and the multiple coils 42 are magnetically coupled. The core 41 may be provided separately for each coil 42. The inductor component may be packaged in such a manner that the multiple coils 42 are aligned in a predetermined direction, for example.

[0087] (Disclosure of technical ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be written in a multiple dependent form, with the subsequent clause referring to the preceding clause as an alternative. Furthermore, some clauses may be written in a multiple dependent form, referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0088] <Technical philosophy 1> a substrate (30) having a plurality of lands (33); an inductor component (40) having a core (41) and a plurality of coils (42) arranged on the core; a solder (70) for joining the coil and the land; Equipped with the plurality of coils are arranged in a predetermined direction perpendicular to the thickness direction of the substrate, The land joined to the coil includes a plurality of mounting lands (331) provided corresponding to the coil and constituting a circuit together with the coil, and at least one stress relief land (332) provided at a position separated from the mounting lands.

[0089] <Technical philosophy 2> The electronic device described in Technical Idea 1, wherein the stress relief land is provided directly below the coil, which is positioned closer to the end of the inductor component than the center of the inductor component in the specified direction.

[0090] <Technical philosophy 3> The electronic device according to Technical Idea 2, wherein the stress relaxation land is provided directly below the coil located at the end of the plurality of coils in the predetermined direction.

[0091] <Technical philosophy 4> The coil has a first terminal portion (421) and a second terminal portion (422) as terminal portions for external connection, The mounting land includes a first mounting land (3311) joined to the first terminal portion, and a second mounting land (3312) provided at a position different from the first mounting land in a direction perpendicular to both the plate thickness direction and the predetermined direction, and joined to the second terminal portion, The electronic device according to any one of Technical Concepts 1 to 3, wherein the stress relaxation land is located between the first mounting land and the second mounting land in the orthogonal direction.

[0092] <Technical philosophy 5> the mounting lands provide a wiring function on the substrate; The electronic device according to any one of Technical Concepts 1 to 4, wherein the stress relaxation lands do not provide a wiring function on the substrate.

[0093] <Technical philosophy 6> The electronic device according to any one of Technical Concepts 1 to 5, wherein the stress relaxation lands are smaller than the mounting lands in a plan view in the plate thickness direction.

[0094] <Technical philosophy 7> The electronic device according to Technical Idea 6, wherein the length of the stress relaxation land is shorter than the length of the mounting land in a direction perpendicular to both the plate thickness direction and the predetermined direction.

[0095] <Technical philosophy 8> The coil has a recess (426) at a position facing the stress relaxation land, The electronic device according to any one of Technical Concepts 1 to 7, wherein the solder that joins the coil and the stress relaxation land is disposed in the recess.

[0096] <Technical philosophy 9> a plurality of switching devices (50) and capacitors (60) mounted on the substrate and constituting a multiphase power supply together with the inductor components; An electronic device described in any one of Technical Ideas 1 to 8, wherein the inductor component is arranged between the switching device and the capacitor in a direction perpendicular to both the plate thickness direction and the specified direction. [Explanation of symbols]

[0097] 10... multiphase power supply, 11... power supply circuit, 12... capacitor, 13H, 13L... switching element, 14... inductor, 14C... coupled inductor, 15... ECU, 16... control unit, 17... processor, 20... electronic device, 30... substrate, 30a... one surface, 31... insulating substrate, 32... conductor, 33... land, 331, 3311, 3312... mounting land, 332... stress relief land, 333... extension portion, 334... notch, 34, 341, 342, 343, 344... wiring Wire, 40... coupled inductor, 401... inductor, 41... core, 411, 4111, 4112... core core, 412, 413... end core, 412a, 413a... upper surface, 412b, 413b... lower surface, 412c, 412d, 412e, 412f, 413c, 413d, 413e, 413f... side surface, 42... coil, 421, 422... terminal portion, 423, 424... side wall portion, 425... upper wall portion, 426... recess, 50... switching device, 60... capacitor, 70... solder

Claims

1. a substrate (30) having a plurality of lands (33); an inductor component (40) having a core (41) and a plurality of coils (42) arranged on the core; Solder (70) that joins the coil and the land; Equipped with the plurality of coils are arranged in a predetermined direction perpendicular to the thickness direction of the substrate, The land joined to the coil includes a plurality of mounting lands (331) provided corresponding to the coil and constituting a circuit together with the coil, and at least one stress relief land (332) provided at a position separated from the mounting lands.

2. 2. The electronic device according to claim 1, wherein the stress relaxation land is provided immediately below the coil that is positioned closer to an end of the inductor component than to a center of the inductor component in the predetermined direction.

3. 3. The electronic device according to claim 2, wherein the stress relaxation land is provided immediately below the coil located at an end of the plurality of coils in the predetermined direction.

4. The coil has a first terminal portion (421) and a second terminal portion (422) as terminal portions for external connection, The mounting land includes a first mounting land (3311) joined to the first terminal portion, and a second mounting land (3312) provided at a position different from the first mounting land in a direction perpendicular to both the plate thickness direction and the predetermined direction, and joined to the second terminal portion, The electronic device according to claim 3 , wherein the stress relaxation land is located between the first mounting land and the second mounting land in the orthogonal direction.

5. the mounting lands provide a wiring function on the substrate; The electronic device according to claim 4 , wherein the stress relief lands do not provide a wiring function in the substrate.

6. The electronic device according to claim 5 , wherein the stress relaxation lands are smaller than the mounting lands in a plan view in the plate thickness direction.

7. 7. The electronic device according to claim 6, wherein the length of the stress relaxation land is shorter than the length of the mounting land in the orthogonal direction.

8. The coil has a recess (426) at a position facing the stress relaxation land, 8. The electronic device according to claim 1, wherein the solder that joins the coil and the stress relaxation land is disposed in the recess.

9. a plurality of switching devices (50) and capacitors (60) mounted on the substrate and constituting a multiphase power supply together with the inductor components; The electronic device according to any one of claims 1 to 7, wherein the inductor component is disposed between the switching device and the capacitor in a direction perpendicular to both the plate thickness direction and the predetermined direction.

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