WO2021002200A1

WO2021002200A1 - Circuit board and circuit board module

Info

Publication number: WO2021002200A1
Application number: PCT/JP2020/023799
Authority: WO
Inventors: セルゲイモイセエフ; 直毅加藤; 伊藤　賢; 佳孝岩田; 田中　克典
Original assignee: 株式会社豊田自動織機
Priority date: 2019-07-01
Filing date: 2020-06-17
Publication date: 2021-01-07
Also published as: JP2021009918A; JP7136023B2

Abstract

This circuit board comprises a first layer having a first circuit and a second layer having a second circuit that is different from the first circuit. The first layer and the second layer are arranged to overlap each other. The second circuit is disposed to have an overlapping part that overlaps wiring of the first circuit when viewed from a lamination direction that is a direction in which the first layer and the second layer overlap each other. The second circuit is disposed such that a current generated in the overlapping part due to a magnetic flux caused by the current flowing in the wiring of the first circuit has an allowable value.

Description

Circuit board and circuit board module

This disclosure relates to circuit boards and circuit board modules.

For example, Patent Document 1 discloses a circuit board in which a plurality of layers having a circuit are stacked. In the circuit board disclosed in Patent Document 1, a first layer having a power circuit and a second layer having a control circuit are overlapped. The power circuit includes a power element. The control circuit includes a control element that controls the power element.

Japanese Unexamined Patent Publication No. 2016-225656

When a current flows through the circuit, magnetic flux is generated. When a plurality of layers having circuits are stacked, the magnetic flux generated by the current flowing through each circuit can induce a current in another circuit. Then, a problem may occur due to the current induced by the magnetic flux. For example, when the first layer having a power circuit and the second layer having a control circuit are overlapped as in Patent Document 1, the control element causes the magnetic flux generated by the current flowing in the power circuit. It may perform unintended operation.

An object of the present disclosure is to provide a circuit board and a circuit board module capable of reducing the influence of magnetic flux.

The circuit board according to one aspect of the present disclosure includes a first layer having a first circuit and a second layer having a second circuit different from the first circuit, and the first layer. The layer and the second layer are arranged so as to overlap each other, and the second circuit is viewed from the stacking direction in which the first layer and the second layer overlap each other. The second circuit is arranged so as to have an overlapping portion that overlaps with the wiring of the circuit, and the current generated in the overlapping portion due to the magnetic flux generated by the current flowing through the wiring of the first circuit is the allowable value. It is arranged so as to be.

The circuit board module according to one aspect of the present disclosure includes a first circuit board having a first circuit and a second circuit board having a second circuit different from the first circuit. The first circuit board and the second circuit board are arranged so as to overlap each other, and the second circuit is from the stacking direction in which the first circuit board and the second circuit board overlap each other. As seen, the second circuit is arranged so as to have an overlapping portion that overlaps with the wiring of the first circuit, and the second circuit has the overlapping portion due to the magnetic flux generated by the current flowing through the wiring of the first circuit. It is arranged so that the current generated in is an allowable value.

Schematic diagram of the motor and the motor drive device. The schematic block diagram of the drive circuit included in the motor drive device of FIG. The perspective view which shows typically the circuit board. The perspective view which shows the positional relationship between the output wiring and a closed circuit. A plan view showing the positional relationship between the output wiring and the closed circuit. The figure for demonstrating the relationship between the closed circuit and the magnetic flux generated by the current flowing through the output wiring. The figure which shows the circuit board of the comparative example. The figure which shows typically the 2nd circuit in the modification.

Hereinafter, one embodiment of the circuit board will be described.

As shown in FIG. 1, the motor drive device 10 is a device for driving the motor 11. The motor 11 of the present embodiment is a three-phase AC motor including three coils U, V, and W. The motor drive device 10 includes a battery BA, a smoothing capacitor C, a control device 12, an inverter circuit 21 which is a first circuit, and a drive circuit D which is a second circuit.

The inverter circuit 21 includes a conversion unit 22 and

output wirings

23, 24, and 25, which are wirings for the first circuit. The conversion unit 22 includes six switching elements Q1 to Q6, which are power elements. As the switching elements Q1 to Q6, for example, IGBTs (insulated gate bipolar transistors) or MOSFETs are used. The switching element Q1 forming the U-phase upper arm and the switching element Q2 forming the U-phase lower arm are connected in series with each other. The switching element Q3 constituting the V-phase upper arm and the switching element Q4 constituting the V-phase lower arm are connected in series with each other. The switching element Q5 forming the W phase upper arm and the switching element Q6 forming the W phase lower arm are connected in series with each other.

Output wirings

23, 24, and 25 are connected to the connection points of the upper arm switching elements Q1, Q3, and Q5 and the corresponding lower arm switching elements Q2, Q4, and Q6 for each phase. The

output wirings

23, 24, and 25 are connected to the motor 11. A battery BA is connected to the switching elements Q1 to Q6 via a smoothing capacitor C. The conversion unit 22 converts the DC power of the battery BA into AC power. The

output wirings

23, 24, and 25 output the AC power output from the conversion unit 22 to the motor 11. As a result, the motor 11 is driven. The inverter circuit 21 is a power circuit that performs power conversion.

The control device 12 is mainly composed of, for example, a microcomputer. The process executed by the control device 12 may be performed by the CPU executing the program stored in the storage unit, or may be performed through the hardware process executed by the dedicated electronic circuit. The control device 12 controls the motor 11 via the inverter circuit 21 by performing current feedback control using a vector control method based on, for example, the target torque of the motor 11 requested by another control device or the like. The control device 12 outputs a control signal for controlling the switching elements Q1 to Q6 to the drive circuit D. The drive circuit D controls the switching elements Q1 to Q6 according to the control signal.

The drive circuit D is individually provided for each of the switching elements Q1 to Q6. As shown in FIG. 2, each drive circuit D includes a first drive switching element T1, a second drive switching element T2, two resistance elements R1 and R2, a drive capacitor C1, and a gate resistor. It includes R3, two connection resistors R4 and R5, and two connection capacitors C2 and C3.

As the first drive switching element T1, for example, an NPN type transistor is used. As the second drive switching element T2, for example, a PNP type transistor is used.

The two drive switching elements T1 and T2 and the two resistance elements R1 and R2 are connected in series with each other. The emitter of the first drive switching element T1 and the emitter of the second drive switching element T2 are connected to each other. The first end of the resistance element R1 is connected to the collector of the first drive switching element T1. The first end of the resistance element R2 is connected to the collector of the second drive switching element T2. The collector of the second drive switching element T2 is grounded via the resistance element R2. The drive switching elements T1 and T2 and the resistance elements R1 and R2 form a series connection.

The drive capacitor C1 is connected in parallel to a series connector composed of drive switching elements T1 and T2 and resistance elements R1 and R2. The first end of the drive capacitor C1 is connected to the second end of the resistance element R1. The second end of the drive capacitor C1 is connected to the second end of the resistance element R2. Therefore, the drive switching elements T1 and T2, the resistance elements R1 and R2, and the drive capacitor C1 constituting the series connection form a closed circuit 31. The connection points of the two drive switching elements T1 and T2 are connected to one end of the gate resistor R3. The other end of the gate resistor R3 is connected to any of the gates of the switching elements Q1 to Q6.

The base of the first drive switching element T1 and the base of the second drive switching element T2 are connected to the control device 12 via a resistor.

The connection resistor R4 and the connection capacitor C2 are connected in parallel to each other. The first end of the connection resistor R4 is connected to the base of the drive switching element T1. The second end of the connection resistor R4 is connected to the second end of the resistor element R1 and the first end of the drive capacitor C1.

The first end of the connection capacitor C2 is connected to the base of the drive switching element T1. The second end of the connection capacitor C2 is connected to the second end of the resistance element R1 and the first end of the drive capacitor C1. That is, the closed circuit 33 is formed by the resistance element R1, the connection capacitor C2, and the first drive switching element T1, and the closed circuit 34 is formed by the resistance element R1, the connection resistor R4, and the first drive switching element T1. Will be done.

The connection resistor R5 and the connection capacitor C3 are connected in parallel to each other. The first end of the connection resistor R5 is connected to the base of the drive switching element T2. The second end of the connection resistor R5 is connected to the second end of the resistor element R2 and the second end of the drive capacitor C1.

The first end of the connection capacitor C3 is connected to the base of the drive switching element T2. The second end of the connection capacitor C3 is connected to the second end of the resistance element R2 and the second end of the drive capacitor C1. That is, the closed circuit 35 is formed by the resistance element R2, the connection capacitor C3, and the second drive switching element T2, and the closed circuit 36 is formed by the resistance element R2, the connection resistor R5, and the second drive switching element T2. Will be done.

The drive circuit D configured as described above switches the switching elements Q1 to Q6 on and off by the operation of the two drive switching elements T1 and T2. The two drive switching elements T1 and T2 are control elements that control the switching elements Q1 to Q6. The drive circuit D is a control circuit. The drive circuit D is driven by a power supply from a power supply circuit that generates electric power to drive the drive circuit D. The drive circuit D amplifies the control signal from the control device 12, and outputs the control signal as a drive signal to the gates of the corresponding switching elements Q1 to Q6. As a result, in each phase of the inverter circuit 21, the upper arm switching elements Q1, Q3 and Q5 and the lower arm switching elements Q2, Q4 and Q6 are alternately turned on.

Next, the circuit board 20 on which the inverter circuit 21 and the drive circuit D are mounted will be described.

As shown in FIG. 3, the circuit board 20 includes a first layer 26 having an inverter circuit 21 and a second layer 32 having a drive circuit D. The first layer 26 and the second layer 32 are arranged so as to overlap each other. The "state in which the first layer 26 and the second layer 32 are arranged in an overlapping manner" is a state in which the first layer 26 and the second layer 32 are arranged in contact with each other. Alternatively, the first layer 26 and the second layer 32 may be arranged so as to be separated from each other and face each other. That is, "a state in which the first layer 26 and the second layer 32 are arranged so as to overlap each other" means that the first layer 26 and the second layer 32 are arranged so as to be in contact with or separated from each other. It is in a state of being done. In the present embodiment, the first layer 26 and the second layer 32 are overlapped so that the thickness direction of the first layer 26 and the thickness direction of the second layer 32 coincide with each other. The "state in which the thickness direction of the first layer 26 and the thickness direction of the second layer 32 coincide with each other" allows a slight deviation due to a tolerance or the like. The circuit board 20 is a multilayer board in which a plurality of insulating layers are laminated, and the first layer 26 and the second layer 32 are insulating layers.

The output wirings 23, 24, and 25 are bus bars connected to the conversion unit 22. That is, the

output wirings

23, 24, and 25 are wide wirings in which the width direction is longer than the thickness direction. Assuming that the overlapping direction of the first layer 26 and the second layer 32 is the stacking direction, the thickness direction of the

output wirings

23, 24, 25 and the stacking direction are the same direction.

At least a part of each drive circuit D is arranged so as to be overlapped with any of the

output wirings

23, 24, and 25 when viewed from the stacking direction. That is, each drive circuit D is arranged so as to have an overlapping portion that overlaps any of the

output wirings

23, 24, and 25 when viewed from the stacking direction. Hereinafter, for convenience of explanation, the drive circuit D arranged so as to overlap the output wiring 25 among the six drive circuits D corresponding to the six switching elements Q1 to Q6 will be described, but each of the drive circuits D will be described. It overlaps with any of the three

output wirings

23, 24, and 25 when viewed from the stacking direction. For example, two drive circuits D for driving U-phase switching elements Q1 and Q2 are arranged so as to overlap the U-phase output wiring 23, and the drive circuits D of each phase are arranged on the same-

phase output wirings

23, 24, 25. It may be arranged in layers. Further, all the drive circuits D may be arranged so as to overlap one of the three

output wirings

23, 24, 25.

As shown in FIGS. 4 and 5, when viewed from the stacking direction, the entire closed circuit 31 of the drive circuit D is arranged so as to overlap the output wiring 25. The closed circuit 31 is an overlapping portion. As shown in FIGS. 4 and 5, the closed circuit 31 will be described as a square frame-shaped wiring for convenience of explanation.

When a current flows through the output wiring 25, a magnetic flux is generated in the direction according to the right-handed screw rule. As a result, an induced voltage due to electromagnetic induction is generated in the drive circuit D, and a current flows through the drive circuit D. The drive circuit D is arranged so that the current induced in the drive circuit D due to the current flowing through the output wiring 25 becomes an allowable value. In FIG. 6, the magnetic flux generated by the current flowing through the output wiring 25 is represented by the magnetic flux line L. In FIG. 6, only one magnetic flux line L is shown, but when the magnetic flux actually generated is represented by the magnetic flux line L, the magnetic flux lines L are plural. A current flows through the drive circuit D due to the induced voltage caused by the magnetic flux. In general, when a planar circuit having an area S is placed in a magnetic field, the induced voltage V generated in the planar circuit having an area S can be expressed by the following equation (1).

θ is the angle formed by the plane of the planar circuit and the virtual line extending in the direction orthogonal to the direction of the magnetic flux. The induced voltage V generated in the closed circuit 31 by the current flowing through the output wiring 25 can be expressed by the following equation (2).

One of the positions where the magnetic flux interlinking twice in the closed circuit 31 passes through the closed circuit 31 is set as the first position P1, and the position where the magnetic flux interlinking twice in the closed circuit 31 passes through the closed circuit 31. The position different from the first position P1 is referred to as the second position P2. θ1 is an angle formed by the virtual line L1 orthogonal to the direction of the magnetic flux passing through the first position P1 and the virtual surface VS including the entire closed circuit 31. θ2 is the angle between the virtual line L2 orthogonal to the direction of the magnetic flux passing through the second position P2 and the virtual surface VS including the entire closed circuit 31.

Here, the output wiring 25 and the virtual surface VS including the entire closed circuit 31 are parallel to each other, and the center CP1 of the output wiring 25 in the width direction of the output wiring 25 and the closed circuit 31 in the width direction of the output wiring 25. It is assumed that the virtual line connecting the center CP2 of the above extends in the direction of the current flowing through the output wiring 25 and the direction orthogonal to the width direction of the output wiring 25. In this case, the first position P1 and the second position P2 are located symmetrically with respect to the center CP2 of the closed circuit 31. Therefore, θ1-θ2 = 0 ° is established, and the induced voltage generated in the closed circuit 31 from the equation (2) becomes 0. The virtual surface VS including the entire closed circuit 31 is a surface including all the wirings constituting the outer frame of the closed circuit 31. It can be said that the width direction of the output wiring 25 is orthogonal to the direction of the current flowing through the output wiring 25 and the thickness direction of the output wiring 25.

As described above, when the magnetic flux interlinking twice in the closed circuit 31 passes symmetrically through the closed circuit 31, θ1 and θ2 have the same value, so that the induced voltage generated in the closed circuit 31 becomes 0. , No current is generated due to magnetic flux. On the other hand, when the magnetic flux interlinking twice in the closed circuit 31 passes asymmetrically with respect to the closed circuit 31, such as when the output wiring 25 and the virtual surface VS including the entire closed circuit 31 are not parallel to each other. Since the values of θ1 and θ2 are different, the induced voltage becomes higher than 0, and a current is generated in the closed circuit 31 due to the magnetic flux. Further, when there is a magnetic flux that passes through the closed circuit 31 once, an induced voltage is generated according to the equation (1). As the center CP1 of the output wiring 25 and the center CP2 of the closed circuit 31 are separated from each other in the width direction of the output wiring 25, the magnetic flux passing through the closed circuit 31 once increases, so that the induced voltage generated in the closed circuit 31 becomes high. Become. When the entire closed circuit 31 faces the output wiring 25, the induced voltage is lower than when only a part of the closed circuit 31 faces the output wiring 25.

For convenience of explanation, the shape of the wiring forming the closed circuit 31 has been described as a square frame shape, but even if the shape of the wiring forming the closed circuit 31 is not a square frame shape, the inside of the closed circuit 31 is twice. If the closed circuit 31 and the output wiring 25 are provided so as to overlap each other so that the magnetic flux interlinking exists, the induced voltage generated in the closed circuit 31 becomes low. Therefore, the value of the current generated in the closed circuit 31 is low regardless of the shape of the wiring forming the closed circuit 31.

As described above, the current generated in the drive circuit D due to the magnetic flux changes according to the positional relationship between the

output wirings

23, 24, 25 and the drive circuit D. Therefore, by adjusting the positional relationship between the

output wirings

23, 24, 25 and the drive circuit D, the current generated in the drive circuit D due to the magnetic flux from the

output wirings

23, 24, 25 can be set as an allowable value. The permissible value differs depending on the type of the second circuit. When the second circuit is the drive circuit D as in the present embodiment, the allowable value is set so that the drive switching elements T1 and T2 do not operate unintentionally due to the current generated in the drive circuit D by the magnetic flux. To. The closed circuit 31 and the bases of the driving switching elements T1 and T2 are connected via connection resistors R4 and R5 and connection capacitors C2 and C3. When an induced voltage is generated by magnetic flux in the closed circuit 31, the driving switching elements T1 and T2 may be unintentionally turned on by a current flowing between the base and the emitter of the driving switching elements T1 and T2. If the drive switching elements T1 and T2 perform an unintended operation, the switching elements Q1 to Q6 are erroneously switched on and off. The switching elements Q1 to Q6 are switched on and off by the current flowing through the closed circuit 31 including the driving switching elements T1 and T2. In the present embodiment, the positional relationship between the drive circuit D and the

output wirings

23, 24, 25 may be adjusted in consideration of the current flowing through the closed circuit 31.

The operation of this embodiment will be described.

When a current flows through the

output wirings

23, 24, 25, magnetic flux is generated. Since the shield layer is not provided between the

output wirings

23, 24, 25 and the drive circuit D, a current may be generated in the drive circuit D due to electromagnetic induction.

As shown in FIG. 7, when the closed circuit 31 expands in the thickness direction of the first layer 26 and θ is brought close to 90 °, the induced voltage generated in the closed circuit 31 is generated as can be grasped from the equation (1). It gets higher. Since the current flowing through the closed circuit 31 becomes large due to the magnetic flux, the switching elements Q1 to Q6 may be erroneously switched on and off. On the other hand, in the embodiment, the induced voltage generated in the closed circuit 31 is lowered so that the current generated in the drive circuit D due to the magnetic flux becomes an allowable value.

The effect of this embodiment will be described.

(1) By arranging the drive circuit D in consideration of the magnetic flux generated by the current flowing through the

output wirings

23, 24, 25, the current generated in the drive circuit D due to the magnetic flux becomes an allowable value. Therefore, the influence of the magnetic flux on the drive circuit D can be reduced.

(2) When viewed from the stacking direction, the entire closed circuit 31 overlaps with any of the

output wirings

23, 24, and 25. The induced voltage generated in the drive circuit D is lower than that in the case where only a part of the closed circuit 31 overlaps with any of the

output wirings

23, 24, and 25. As a result, the current generated in the drive circuit D due to the magnetic flux can be reduced.

(3) By making the current generated in the drive circuit D due to the magnetic flux an allowable value, it is possible to prevent the drive switching elements T1 and T2 from performing unintended operations. Therefore, it is possible to prevent the switching elements Q1 to Q6 from being erroneously switched on and off.

The embodiment can be changed and implemented as follows. The embodiments and the following modifications can be implemented in combination with each other to the extent that they are technically consistent.

○ The first circuit and the second circuit may be mounted on a circuit board module having a plurality of circuit boards instead of the circuit board 20. The circuit board module includes a first circuit board having a first circuit and a second circuit board having a second circuit different from the first circuit. As the first circuit, for example, an inverter circuit 21 can be used. As the second circuit, for example, a drive circuit D can be used. The first circuit board is an insulating board on which the first circuit is mounted. The second circuit board is an insulating board on which the second circuit is mounted. The first circuit board and the second circuit board are arranged at intervals from each other. The first circuit board and the second circuit board are arranged so as to be overlapped in the stacking direction (in other words, to face the stacking direction). That is, when the circuit board 20 of the embodiment shown in FIG. 3 is regarded as a circuit board module, the first layer 26 and the second layer 32 can be regarded as insulating boards, respectively, and the two insulating boards are regarded as each other. Arranged at intervals. The second circuit is arranged so as to overlap the wiring of the first circuit at least partially when viewed from the direction in which the first circuit board and the second circuit board overlap. That is, the second circuit is arranged so as to have an overlapping portion that overlaps with the wiring of the first circuit when viewed from the direction in which the first circuit board and the second circuit board overlap. The second circuit is arranged so that the current generated in the overlapping portion due to the magnetic flux generated by the current flowing through the wiring of the first circuit becomes an allowable value.

○ The first circuit may be other than the power circuit. For example, the first circuit may be a circuit on which an element such as a smoothing capacitor C is mounted.

○ The second circuit may be an arithmetic circuit used for the sensor. For example, the arithmetic circuit may be used for a current sensor. The current sensor includes a shunt resistor and an arithmetic circuit. The arithmetic circuit calculates the value of the current flowing through the detection target from the current flowing through the shunt resistor and the voltage across the shunt resistor. When the arithmetic circuit is arranged under the influence of magnetic flux, an error may occur in the detection result of the sensor due to the current generated by the magnetic flux. When the arithmetic circuit used in the sensor is the second circuit of the present disclosure, the permissible value of the current generated by the magnetic flux is set within the range of the error permissible as the detection result of the sensor. The permissible error as a result of sensor detection depends on the mounting target on which the sensor is mounted. Therefore, the arithmetic circuit may be arranged so that the value of the current generated in the arithmetic circuit due to the magnetic flux becomes a value allowed by the sensor and the mounting target.

○ The power circuit may be any one that converts electric power, and may be, for example, a converter circuit used in a DC / DC converter. Examples of the power element included in the power circuit include a diode and a thyristor in addition to the switching element.

○ As shown in FIG. 8, the second circuit 40 includes a first portion 41 which is an overlapping portion overlapping the output wiring 25 and a second portion 42 which does not overlap the output wiring 25 when viewed from the stacking direction. , May be provided. In this case, the current generated by the magnetic flux tends to be larger in the second portion 42 than in the first portion 41. A capacitor 43 is connected to the connection wiring 44 that interconnects the first portion 41 and the second portion 42 in order to suppress the current generated in the second portion 42 from flowing to the first portion 41. .. The capacitor 43 is connected in parallel to the first portion 41 and the second portion 42. The capacitor 43 overlaps the output wiring 25 when viewed from the stacking direction. By suppressing the influence of the second portion 42, which does not overlap with the output wiring 25 and tends to generate a current due to electromagnetic induction, the influence of the magnetic flux on the first portion 41 can be reduced. In this case, the second circuit 40 may be arranged so that the current generated in the first portion 41 by the magnetic flux becomes an allowable value.

Further, if the area of the second portion 42 is small, the induced voltage generated in the second portion 42 becomes low, as can be grasped from the equation (1). Therefore, if the area of the second circuit 40 is small and the current generated in the second circuit 40 by the magnetic flux is small, it is not necessary to provide the capacitor 43 in the connection wiring 44. In this case, the first portion 41 may be arranged so that the current generated in the first portion 41 due to the magnetic flux becomes an allowable value.

○ A part of the closed circuit 31 does not have to overlap with the output wiring 25 when viewed from the stacking direction.

○ The second circuit does not have to be a closed circuit.

○ The drive circuit D is arranged so that the current flowing in at least one of the

closed circuits

33, 34, 35, 36 due to the magnetic flux generated by the current flowing in the

output wirings

23, 24, 25 becomes an allowable value. May be good. That is, in the case of a closed circuit in which the driving switching elements T1 and T2 may perform unintended operations due to the flow of the current generated by the magnetic flux, the current flowing in at least one of the closed circuits shall be an allowable value. The drive circuit D may be arranged.

○ The wiring of the first circuit does not have to be the

output wirings

23, 24, 25, and the wiring for input for inputting the power from the battery BA to the inverter circuit 21 and the pattern wiring constituting the inverter circuit 21 are instantaneous. Any wiring may be used as long as the wiring allows current to flow in one direction.

○ The virtual surface VS including the entire closed circuit 31 may be arranged so as to be inclined with respect to the surfaces of the output wirings 23 to 25 facing the virtual surface VS including the entire closed circuit 31.

○ A shield layer may be provided between the first layer 26 and the second layer 32. In this case, the shield layer can be made thinner by reducing the current generated in the drive circuit D due to the magnetic flux by setting the arrangement relationship between the drive circuit D and the

output wirings

23, 24, 25.

○ The circuit board 20 may include at least a first layer 26 and a second layer 32, and may include three or more layers.

○ The drive circuit D may include one of the connection resistor R4 and the connection capacitor C2. The drive circuit D may include one of the connection resistor R5 and the connection capacitor C3.

Claims

A first layer with a first circuit and
A second layer having a second circuit different from the first circuit is provided.
The first layer and the second layer are arranged so as to overlap each other.
The second circuit is arranged so as to have an overlapping portion that overlaps with the wiring of the first circuit when viewed from the stacking direction in which the first layer and the second layer overlap.
The second circuit is a circuit board arranged so that the current generated in the overlapping portion due to the magnetic flux generated by the current flowing through the wiring of the first circuit becomes an allowable value.
The second circuit includes a closed circuit.
The circuit board according to claim 1, wherein the entire closed circuit overlaps with the wiring of the first circuit when viewed from the stacking direction.
The first circuit is a power circuit including a power element.
The circuit board according to claim 1 or 2, wherein the second circuit is a control circuit including a control element that controls the power element.
The second circuit is
The first part, which is the overlapping part, and
A second portion that does not overlap the wiring of the first circuit when viewed from the stacking direction, and
The connection wiring that interconnects the first part and the second part,
A capacitor connected to the connection wiring so as to be connected in parallel to the first portion and the second portion, and which overlaps with the wiring of the first circuit when viewed from the stacking direction. The circuit board according to claim 1.
A first circuit board having a first circuit and
A second circuit board having a second circuit different from the first circuit is provided.
The first circuit board and the second circuit board are arranged so as to overlap each other.
The second circuit is arranged so as to have an overlapping portion that overlaps with the wiring of the first circuit when viewed from the stacking direction in which the first circuit board and the second circuit board overlap. Ori,
The second circuit is a circuit board module arranged so that the current generated in the overlapping portion due to the magnetic flux generated by the current flowing in the wiring of the first circuit becomes an allowable value.