JP7309515B2 - circuit board - Google Patents

Description

The present invention relates to circuit boards.

In recent years, computerization is progressing rapidly in the industrial world. In particular, in the field of automobiles, where hybrid cars and electric cars are becoming widespread, electrical components are used not only in control systems but also in drive systems such as motors.

In the circuit board on which these parts are mounted, it is necessary to provide a wiring pattern through which a large current of the driving system flows, in addition to the normal wiring pattern through which the signal of the control element system with a relatively small current flows.

As a countermeasure, a method of connecting multiple circuit boards with wiring patterns for the control system and the drive system respectively, or a multilayer structure of the conductor layer, and a wiring pattern through which a large current flows and a normal wiring pattern are laminated. method has been used.

However, the former method has problems such as an increase in the number of circuit boards and an increase in the size of the unit. On the other hand, in the latter method, although an increase in the size of the unit can be reduced, there is a problem that the circuit board becomes large because the degree of freedom in wiring design is reduced.

In order to solve such problems, a circuit board (see, for example, Patent Document 1) in which a thick conductor wiring pattern through which a large current flows and a thin conductor wiring pattern through which a control signal flows are formed in the same layer, or the thickness of the conductor wiring pattern is proposed. A circuit board has been proposed in which the impedance is lowered by providing a large number of through holes in a wiring pattern through which a large current flows without changing the impedance.

JP 2015-119073 A

However, in the technique described in Patent Document 1, since the thick conductor wiring pattern and the thin conductor wiring pattern are formed in the same layer, the size including the thickness of the circuit board becomes large, and the circuit board becomes large. cannot solve the problem completely.

Moreover, the method of providing a large number of through holes in a wiring pattern through which a large current flows also reduces the degree of freedom in designing the wiring, and thus does not solve the problem of increasing the size of the circuit board.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above problems, and provides a circuit board that can secure a sufficient current capacity for a large current while preventing the circuit board from increasing in size.

Mode 1: In one or more embodiments of the present invention, a drive circuit for driving a load, a through hole provided in each of a power supply pattern and a ground pattern of the drive circuit, and a through hole passing through the through hole and a lead of a capacitor arranged between the power pattern and the ground pattern , the lead of the capacitor being soldered from the surface layer to the back surface of the circuit board , and the drive circuit a first switching element having a power terminal connected to the power pattern; a second switching element having a ground terminal connected to the ground pattern and connected in series with the first switching element; wherein the capacitor is mounted on the rear side of the mounting surface of the first switching element and the second switching element, and the lead of the capacitor is in close proximity between the power supply terminal and the ground terminal. A circuit board is proposed which is characterized in that

Mode 2: One or more embodiments of the present invention proposes a circuit board characterized in that the leads of the capacitor have a lower impedance than the through-holes.

Mode 3 : In one or more embodiments of the present invention, the drive circuit includes a plurality of the first switching elements and the second switching elements, and the capacitor includes a plurality of the first switching elements. A circuit board is proposed, characterized in that the power supply terminals of the elements and the ground terminals of the plurality of second switching elements are arranged in close proximity to each other.

According to one or more embodiments of the present invention, there is an advantage that sufficient current capacity for large currents can be ensured while preventing an increase in the size of the circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view which shows the rotating electric machine which concerns on embodiment of this invention in the state which partially disassembled. It is the longitudinal section seen from the 2nd direction one side which shows the rotary electric machine concerning the embodiment of the present invention. 3 is a side view seen from one side in the first direction, showing a connection state between the bus bar and the connector shown in FIG. 2; FIG. (A) is a bottom view showing the ECU unit shown in FIG. 1 as seen from below, and (B) is a side view showing the ECU unit of (A). 5 is an exploded perspective view of the ECU unit shown in FIG. 4, viewed from below; FIG. 5 is an exploded perspective view of the ECU unit shown in FIG. 4, viewed from above; FIG. FIG. 6 is a bottom view of the heat sink shown in FIG. 5 as viewed from below; FIG. 7 is a top plan view of the circuit board shown in FIG. 6; FIG. 3 is a diagram illustrating an electrical connection form between a drive circuit and motor windings as a load; FIG. 4 is a diagram illustrating a step sequence of a drive circuit; It is the figure which showed the arrangement|positioning state in the circuit board of the rod-shaped conductor member. FIG. 4 is a view showing an arrangement state when lead terminals of a capacitor are used as bar-shaped conductor members; FIG. 3 is a diagram showing an arrangement example of switching circuits that constitute a drive circuit; FIG. 3 is a diagram showing an example of wiring in a package in an FET that constitutes a switching circuit; FIG. 4 is a diagram showing an example in which two switching circuits are arranged close to each other;

<Embodiment>
An embodiment of the present invention will be described below with reference to FIGS. 1 to 12. FIG.
Hereinafter, the circuit board 70 according to the present embodiment will be described as a circuit board that constitutes the ECU unit 14 for driving and controlling the rotating electric machine 10 .
The rotating electrical machine 10 is configured as, for example, a rotating electrical machine applied to a steering device of a vehicle (automobile). As shown in FIGS. 1 and 2, the rotating electric machine 10 is formed in a substantially columnar shape as a whole. The rotating electric machine 10 also includes a motor section 12 and an ECU unit 14 for controlling the rotation of the motor section 12 .

In the following description, one axial direction side of the rotating electric machine 10 (arrow A direction side in FIGS. 1 and 2) is defined as the lower side of the rotating electric machine 10, and the other axial direction side of the rotating electric machine 10 (FIGS. 1 and 2) ) is the upper side of the rotary electric machine 10 . In the following description, when the up-down direction is used, the up-down direction of the rotating electric machine 10 is indicated unless otherwise specified.
Further, in the following description, a direction orthogonal to the vertical direction in plan view from above is defined as a first direction (see arrows C and D in FIGS. 1 and 2), and The orthogonal direction is the second direction (see arrows E and F in FIG. 1).
Further, in a plan view, an overhead line passing through the axis AL of the rotating electrical machine 10 and extending in the first direction is defined as a first reference line L1 (see FIGS. 4 and 7), and passes through the axis AL of the rotating electrical machine 10. The overhead line extending in the second direction is the second reference line L2 (see FIGS. 4 and 7).

As shown in FIGS. 1 and 2, the motor unit 12 is configured as a three-phase AC brushless motor. The motor section 12 includes a housing 20 and a plate holder 24, a rotating shaft 28, a stator 34, a rotor 40, and a busbar unit 46 housed in the housing 20. As shown in FIG.

The housing 20 is formed in a substantially bottomed cylindrical shape that is open upward, and constitutes an outer shell of the rotating electric machine 10 . A pair of mounting pieces 20A are integrally formed on the outer peripheral portion of the lower end portion of the housing 20 . The pair of mounting pieces 20A are arranged with the axial direction of the housing 20 as the plate thickness direction, and are arranged from the housing 20 on one side in the first direction (arrow C direction side in FIGS. 1 and 2) and the other side in the first direction (in FIG. 1 and arrow D direction side in FIG. 2). A mounting hole 20A1 is formed through the mounting piece 20A. A fastening member such as a bolt (not shown) is inserted into the mounting hole 20A1, and the housing 20 (that is, the rotating electric machine 10) is fixed to the steering device by the fastening member.

A plurality of (in the present embodiment, three) fixed portions 20B projecting radially outward are formed on the outer peripheral portion of the open end portion of the housing 20 . One fixing portion 20B protrudes from the housing 20 to one side in the first direction, and the three fixing portions 20B are arranged at regular intervals in the circumferential direction of the housing 20 . A screw portion 20B1 for fixing a heat sink 60, which will be described later, is formed through the fixing portion 20B, and a female screw is formed on the inner peripheral surface of the screw portion 20B1.

In addition, a bottomed cylindrical fixed cylinder portion 20C that protrudes downward is integrally formed in the central portion of the bottom wall of the housing 20. A rotating shaft 28, which will be described later, is installed in the fixed cylinder portion 20C. A first bearing 22 is fitted for support. An insertion hole 20C1 for inserting a rotating shaft 28, which will be described later, is formed through the bottom wall of the fixed cylindrical portion 20C. there is

The plate holder 24 is formed in a substantially circular plate shape with the plate thickness extending in the vertical direction, and is fitted in the middle portion of the housing 20 in the vertical direction. A central portion of the plate holder 24 is formed with an insertion hole 24A for inserting a rotation shaft 28, which will be described later. Further, a second bearing 26 is fixed to the central portion of the plate holder 24 for supporting a rotation shaft 28, which will be described later, and the second bearing 26 and the first bearing 22 are arranged coaxially.

The rotating shaft 28 is formed in the shape of a round bar extending in the vertical direction, and is arranged coaxially with the housing 20 inside the housing 20 . A lower end portion of the rotating shaft 28 is rotatably supported by a first bearing 22 , and an upper end portion of the rotating shaft 28 is rotatably supported by a second bearing 26 . An upper end portion of the rotating shaft 28 protrudes upward with respect to the plate holder 24, and a magnet 30 is fixed to the upper end portion. On the other hand, the lower end of the rotary shaft 28 protrudes downward from the bottom wall of the housing 20, and a gear 32 connected to the steering device is fixed to the lower end.

The stator 34 is arranged below the plate holder 24 inside the housing 20 and radially outside the rotating shaft 28 . The stator 34 has a stator core 36 made of a magnetic material, and the stator core 36 is formed in a cylindrical shape and fitted inside the housing 20 . Windings 38 corresponding to the U-phase, V-phase, and W-phase are wound around the stator core 36 .

The rotor 40 has a rotor core 42 , and the rotor core 42 is formed in a cylindrical shape whose axial direction is the vertical direction, and is arranged radially inside the stator 34 . The rotary shaft 28 is fitted into the axial center portion of the rotor core 42 so that the rotor core 42 (rotor 40) and the rotary shaft 28 can rotate integrally. A plurality of magnets 44 (permanent magnets) are fixed in the rotor core 42 . As a result, the rotor 40 and the rotary shaft 28 are integrally rotated around the axis AL by applying currents to the U-phase, V-phase, and W-phase windings 38 of the stator 34 .

The busbar unit 46 is arranged above the stator 34 and held by the plate holder 24 . The busbar unit 46 includes three busbars 48 corresponding to the U-phase, V-phase, and W-phase windings 38 of the stator 34 and a busbar holder 50 for holding the busbars 48 . One end of the bus bar 48 is connected to each of the U-phase, V-phase, and W-phase windings 38 of the stator 34 . As also shown in FIG. 3, the other end of the busbar 48 is configured as a busbar terminal portion 48A. The busbar terminal portion 48A protrudes upward from the plate holder 24 and is arranged side by side in the second direction. It is The busbar terminal portion 48A is formed in a substantially elongated plate shape extending vertically with the first direction being the plate thickness direction. The busbar terminal portion 48A is connected to a connection terminal 86 of the connector 80, which will be described later.

As shown in FIGS. 1 to 3, the ECU unit 14 is assembled to the open end of the housing 20 and constitutes the upper end of the rotating electric machine 10. As shown in FIG. The ECU unit 14 includes a heat sink 60 , a circuit board 70 as a “board” for controlling the motor section 12 , and a connector assembly 90 connected to the circuit board 70 .

As shown in FIGS. 1 to 7, the heat sink 60 is made of an aluminum alloy or the like with high thermal conductivity. The heat sink 60 is formed in a substantially disk-like shape with the plate thickness direction extending in the vertical direction. A flange portion 60A projecting radially outward is formed integrally with the outer peripheral portion of the upper end portion of the heat sink 60, and the flange portion 60A is formed over the entire circumference of the heat sink 60 in the circumferential direction. The heat sink 60 is fitted into the opening of the housing 20 from above, and the flange portion 60A is arranged adjacent to the upper side of the opening end surface of the housing 20 . Thereby, the opening of the housing 20 is closed by the heat sink 60 . That is, the heat sink 60 constitutes a lid portion of the housing 20 and also constitutes a part of the outer shell of the rotating electric machine 10 .

Also, the flange portion 60A is integrally formed with three first fixing portions 60B projecting radially outward at positions corresponding to the screw portions 20B1 of the housing 20. As shown in FIG. A fixing hole 60B1 is formed through the first fixing portion 60B. The heat sink 60 is fixed to the housing 20 by inserting the fixing screw SC1 into the fixing hole 60B1 from above and screwing it into the screw portion 20B1 of the housing 20 .

A pair of second fixing portions 60C projecting radially outward are formed integrally with the portion of the flange portion 60A on the other side in the first direction. arranged in the same direction. A first fixing screw portion 60C1 for fixing a connector assembly 90, which will be described later, is formed through the second fixing portion 60C, and a female screw is formed on the inner peripheral surface of the first fixing screw portion 60C1. ing.

A seal groove 60</b>D is formed in the vertical intermediate portion of the outer peripheral portion of the heat sink 60 . The seal groove 60</b>D is open radially outward of the heat sink 60 and extends along the entire circumference of the heat sink 60 . A ring-shaped O-ring OL is accommodated in the seal groove 60D, and the O-ring OL is made of an elastic member such as rubber. When the heat sink 60 is fixed to the housing 20 , the O-ring OL is elastically deformed and adheres to the inner peripheral surface of the seal groove 60</b>D and the inner peripheral surface of the housing 20 . As a result, the space between the heat sink 60 and the open end of the housing 20 is sealed by the O-ring OL to ensure airtightness within the housing 20 .

As shown in FIGS. 5 and 7, a first ground portion 61 as a "ground portion" for grounding a circuit board 70, which will be described later, is formed on the outer peripheral portion of the lower surface 60E of the heat sink 60. As shown in FIGS. The first ground portion 61 is formed in the shape of a rib protruding downward from the lower surface 60</b>E of the heat sink 60 and extending along the circumferential direction of the heat sink 60 . In addition, most of the first grounding portion 61 is formed on the outer peripheral portion of the heat sink 60 on one side in the first direction. It is formed in an open, substantially C-shape (arc shape). That is, a stepped portion 62 that is one step lower than the first grounding portion 61 is formed on the outer peripheral portion of the lower surface 60E of the heat sink 60 on the other side in the first direction. Both ends of the first grounding portion 61 in the longitudinal direction are arranged on the other side in the first direction with respect to the second reference line L2 in bottom view (see FIG. 7). In other words, the longitudinal length of the first grounding portion 61 is set to 1/2 or more of the total length of the heat sink 60 in the circumferential direction (in the present embodiment, the length of the first grounding portion 61 in the longitudinal direction is 1/2 or more). is set to approximately 2/3 of the total circumferential length of the heat sink 60). Then, the stepped portion 62 is formed in an arc shape that is open to one side in the first direction when viewed from below.

In addition, the first ground portion 61 includes a first substrate fixing portion 61A, a second substrate fixing portion 61B, and a third substrate fixing portion as three “substrate fixing portions” projecting radially inward of the heat sink 60. 61C, and the top end surfaces (lower surfaces) of the first to third board fixing portions 61A to 61C are flush with the top end surface (lower surface) of the first grounding portion 61. As shown in FIG. The first board fixing part 61A, the second board fixing part 61B, and the third board fixing part 61C are provided with a concave first board fixing screw part 61A1, a second board fixing screw part 61B1, and a concave screw part 61B1, which are open downward. Three board fixing screw portions 61C1 are formed respectively. Female threads are formed on the inner peripheral surfaces of the first board fixing screw portion 61A1, the second board fixing screw portion 61B1, and the third board fixing screw portion 61C1.
Further, the first board fixing portion 61A is formed at one end portion of the first grounding portion 61 in the longitudinal direction, and is located on the one side in the second direction (direction of arrow E in FIG. 7) with respect to the first reference line L1. and arranged on the other side in the first direction with respect to the second reference line L2. The second board fixing portion 61B is formed on one side of the first grounding portion 61 in the longitudinal direction. Specifically, the second board fixing portion 61B is arranged on one side in the second direction with respect to the first reference line L1 and on one side in the first direction with respect to the second reference line L2 in a bottom view. The third board fixing portion 61C is formed on the other side of the first grounding portion 61 in the longitudinal direction. Specifically, when viewed from below, the third board fixing portion 61C is located on the other side of the first reference line L1 in the second direction (direction of arrow F in FIG. 7) and in the first direction with respect to the second reference line L2. It is arranged slightly shifted to one side.

Further, the lower surface 60E of the heat sink 60 is formed with a second ground portion 63 as a "ground portion" for grounding and fixing the circuit board 70, which will be described later. The second ground contact portion 63 is formed in a substantially cylindrical shape with a relatively low height that protrudes downward. bottom surface) are flush with each other. A fourth board fixing screw portion 63A is formed inside the second grounding portion 63, and a female screw is formed on the inner surface of the fourth board fixing screw portion 63A. Further, the second grounding portion 63 is arranged at a position on the other side in the second direction with respect to the first reference line L1 and on one side in the first direction with respect to the second reference line L2 in a bottom view.

A portion of the heat sink 60 on one side in the first direction (specifically, a portion on the one side in the first direction from a position slightly shifted to the other side in the first direction with respect to the second reference line L2) is a circuit board 70 described later. is configured as a heat dissipation portion 65 for dissipating heat generated by the FET 74 of . The heat radiating portion 65 is formed with a first heat radiating portion 65A, a second heat radiating portion 65B, and a third heat radiating portion 65C projecting downward from the lower surface 60E of the heat sink 60 . The first heat radiation portion 65A to the third heat radiation portion 65C are each formed in a substantially rectangular shape with the first direction as the longitudinal direction when viewed from the bottom. The amount of protrusion of the first heat radiation portion 65A to the third heat radiation portion 65C from the bottom surface 60E is set smaller than the amount of protrusion of the first grounding portion 61 from the bottom surface 60E. That is, the bottom surfaces of the first heat radiation portion 65A to the third heat radiation portion 65C are arranged above the bottom surface of the first grounding portion 61. As shown in FIG.

Also, the first heat radiation portion 65A to the third heat radiation portion 65C are arranged side by side with a predetermined interval in the second direction. Specifically, the first heat radiation portion 65A is arranged between the third substrate fixing portion 61C and the second grounding portion 63 in a bottom view. In other words, the third board fixing portion 61C, the first heat radiation portion 65A, and the second ground portion 63 are arranged side by side in this order on one side in the second direction.
The second heat radiation portion 65B and the third heat radiation portion 65C are arranged side by side in the second direction at a position between the second substrate fixing portion 61B and the second grounding portion 63 in bottom view. In other words, the second grounding portion 63, the second heat radiation portion 65B, the third heat radiation portion 65C, and the second substrate fixing portion 61B are arranged side by side in this order on one side in the second direction.

A pair of positioning portions 66 and 67 are formed on the lower surface 60E of the heat sink 60 for positioning the connector 80 of the circuit board 70, which will be described later. The positioning portions 66 and 67 protrude downward from the lower surface 60E of the heat sink 60, and the amount of protrusion of the positioning portions 66 and 67 from the lower surface 60E is larger than the amount of protrusion of the first ground portion 61 from the lower surface 60E. set small. The positioning portions 66 and 67 are arranged on the outer peripheral side of the lower surface 60</b>E of the heat sink 60 on the one side in the first direction, and are arranged adjacent to the first grounding portion 61 radially inward. Specifically, the pair of positioning portions 66 and 67 are arranged at positions symmetrical in the second direction with respect to the first reference line L1 in bottom view.

A concave first positioning hole 66A that opens downward is formed in the lower surface of the positioning portion 66 on one side in the second direction, and the first positioning hole 66A is formed in a circular shape when viewed from the bottom. . On the other hand, a concave second positioning hole 67A that opens downward is formed in the lower surface of the positioning portion 67 on the other side in the second direction. It is formed in a substantially track shape with a direction. The dimension in the width direction (first direction) of the second positioning hole 67A is set to match the diameter of the first positioning hole 66A.

The lower surface 60E of the heat sink 60 is formed with a concave portion 60F that opens downward in a portion (the other side portion in the first direction) excluding the heat radiating portion 65. The concave portion 60F has a substantially hexagonal shape when viewed from the bottom. is formed in A terminal insertion portion 60G as an "insertion portion" for inserting a terminal 94 of a connector assembly 90, which will be described later, is formed through the recess 60F on the other side in the first direction. The terminal insertion portion 60G is formed in a substantially V shape that is open to one side in the first direction when viewed from below. In addition, the terminal insertion portion 60G is arranged on the other side in the first direction with respect to the first grounding portion 61 and radially inside the stepped portion 62 in a bottom view.

As shown in FIG. 6, on the upper surface of the heat sink 60, at one side in the first direction, a recess 60H that opens upward is formed. It is

Further, on the upper surface of the heat sink 60, a plurality of (three in this embodiment) second fixing screws for fixing a connector assembly 90, which will be described later, are provided between the recess 60H and the terminal insertion portion 60G. A portion 60J is formed. The second fixing screw portion 60J is formed in a concave shape that is open to the upper side of the heat sink 60, and a female screw is formed on the inner peripheral surface of the second fixing screw portion 60J. The three second fixing screw portions 60J are arranged at predetermined intervals in the second direction in plan view.

<Structure of circuit board>
As shown in FIGS. 1 to 8, the circuit board 70 is formed in a disk-like shape with the plate thickness direction extending in the vertical direction, and the diameter of the circuit board 70 is set slightly smaller than the diameter of the heat sink 60. It is The circuit board 70 is arranged coaxially with the heat sink 60 and arranged adjacent to the lower side of the first grounding portion 61 and the second grounding portion 63 of the heat sink 60 . As a result, a gap G1 (see FIG. 4B) is formed in the vertical direction between the outer peripheral portion of the circuit board 70 on the other side in the first direction and the stepped portion 62 of the heat sink 60. .

Four board fixing holes 70A (see FIGS. 6 and 8) are formed through the circuit board 70 at positions corresponding to the first board fixing screw portion 61A1 to the fourth board fixing screw portion 63A of the heat sink 60. It is The circuit board 70 is fixed to the heat sink 60 by inserting the fixing screw SC2 into the board fixing hole 70A from below and screwing it into the first to fourth board fixing screw portions 61A1 to 63A. It is Thus, the motor section 12 is arranged on one side (lower side) of the circuit board 70 in the thickness direction.

Here, the portion of the upper surface of the circuit board 70 (the surface facing the heat sink 60 in the vertical direction) that is grounded to the first grounding portion 61 and the second grounding portion 63 of the heat sink 60 is not coated with resist. It is configured as a portion 71 (see the gray-filled portion in FIG. 8). A ground pattern is formed on the non-applied portion 71 of the circuit board 70 , and the ground pattern is in contact with the first grounding portion 61 and the second grounding portion 63 of the heat sink 60 . That is, the circuit board 70 is grounded to the first grounding portion 61 and the second grounding portion 63 of the heat sink 60 .

In addition, the upper surface of the circuit board 70 includes a first area 70AR1 (see the hatched portion in FIG. 8) arranged vertically opposite the heat dissipation portion 65 of the heat sink 60, and a concave portion 60F of the heat sink 60. It is divided into a second area 70AR2 arranged opposite to the vertical direction. First area 70AR1 is mainly provided with power-supply-system electronic components in rotary electric machine 10, and second area 70AR2 is mainly provided with control-system electronic components in rotary electric machine 10. FIG.

Specifically, as shown in FIGS. 6 to 8, a plurality of FETs 74 as “heating elements” are provided (mounted) in the first area 70AR1 of the circuit board . That is, the plurality of FETs 74 are arranged radially inside the first ground portion 61 as viewed from below. The plurality of FETs 74 are arranged at positions corresponding to the first heat radiation portion 65A, the second heat radiation portion 65B, and the third heat radiation portion 65C of the heat sink 60 . Specifically, a pair of FETs 74 are arranged on the circuit board 70 at positions corresponding to the first heat radiation portion 65A, the second heat radiation portion 65B, and the third heat radiation portion 65C of the heat sink 60, respectively. are arranged side by side in the first direction (see FIG. 7). Thereby, a plurality of FETs 74 are arranged in a first group (a group of four FETs 74 corresponding to the second heat radiation portion 65B and the third heat radiation portion 65C) arranged on one side in the second direction with respect to the first reference line L1. and a second group (a group of two FETs 74 corresponding to the first heat radiation portion 65A) arranged on the other side in the second direction with respect to the first reference line L1. A second ground portion 63 of the heat sink 60 is arranged between the first group and the second group of the FETs 74 . More specifically, the first group of FETs 74 is arranged between the second ground portion 63 and the second substrate fixing portion 61B, and the second group of FETs 74 is arranged between the third substrate fixing portion 61C and the second ground portion 63. is placed between.

Further, when the circuit board 70 is fixed to the heat sink 60, a minute gap G2 is formed in the vertical direction between the FET 74 and the first heat radiation portion 65A, the second heat radiation portion 65B, and the third heat radiation portion 65C. The amount of protrusion of the first heat radiation portion 65A, the second heat radiation portion 65B, and the third heat radiation portion 65C from the lower surface 60E of the heat sink 60 is set so that the heat radiation portion 65A, the second heat radiation portion 65B, and the third heat radiation portion 65C protrude from the lower surface 60E (see FIG. 12). Heat dissipation grease (not shown) is interposed in the gap G2. As a result, the heat generated by the FET 74 is transferred to the heat sink 60 via the heat dissipation grease.

On the other hand, a magnetic sensor 72 is provided (mounted) in the central portion of the lower surface (one side surface) of the circuit board 70 . The magnetic sensor 72 is arranged close to the upper side of the magnet 30 on the rotating shaft 28 of the motor section 12, and the magnetic sensor 72 and the magnet 30 are arranged to face each other in the vertical direction (see FIG. 2). Thus, the magnetic sensor 72 detects the rotation amount (rotation angle) of the rotary shaft 28 .

A pair of circular board-side positioning holes 70B (see FIG. 6) are formed through the circuit board 70 at positions corresponding to the first positioning hole 66A and the second positioning hole 67A of the heat sink 60 . The diameter dimension of the board-side positioning hole 70B is set to be substantially the same as the diameter dimension of the first positioning hole 66A.

As described above, the circuit board 70 according to the present embodiment mainly includes the area (70AR1) in which the electronic components of the power supply system in the rotary electric machine 10 through which a large current flows, and the It is divided into an area (70AR 2 ) where control system electronic components are arranged.

In this embodiment, a motor drive circuit as shown in FIG. 9 is exemplified as a circuit through which a large current flows. This motor drive circuit is composed of six Nch MOS FETs 74A, 74B, 74C, 74D, 74E and 74F. More specifically, it is composed of three circuit blocks (switching circuits) consisting of two FETs, and each circuit block (switching circuit) has the drains of FETs 74A, 74B, and 74C connected to VCC (power supply). there is The sources of FETs 74A, 74B and 74C are connected to the drains of FETs 74D, 74E and 74F. Furthermore, the sources of the FETs 74D, 74E, and 74F are connected to GND (ground). A coupling capacitor C1 is provided between VCC and GND.

Also, the source of the FET 74A and the drain of the FET 74D are connected to, for example, the U phase of the motor winding. The source of FET 74B and the drain of FET 74E are connected, for example, to the V phase of the motor winding. The source of FET 74C and the drain of FET 74F are connected to, for example, the W phase of the motor winding.

FIG. 10 shows the step sequence (ON/OFF states) of the FETs 74A, 74B, 74C, 74D, 74E and 74F and the excitation states of the U, V and W phases at that time. For example, in the case of step 1, the FET 74A and the FET 74F are turned on by supplying a drive signal from a control unit (not shown) to the gate of the FET 74A and the gate of the FET 74F. At this time, the winding current flows from the U phase to the W phase, and the U phase is excited to the N pole and the W phase to the S pole. This causes the rotor to rotate 30 degrees. By repeating such operations 12 times, the rotor rotates. That is, when the motor section 12 is rotationally driven, one of the FETs 74A, 74B, and 74C and one of the FETs 74D, 74E, and 74F are turned ON, and the winding current is reduced to VCC ( power supply), a large current always flows from VCC (power supply) to GND (ground).

Further, the power pattern and the ground pattern of the motor drive circuit (driving circuit) are provided with through holes 75 in which the resist ink is not applied to the lands 75A. The through hole 75 is provided with a rod-shaped conductor member 76 penetrating through the through hole 75 . are soldered as shown. Also, the bar-shaped conductor member 76 is made of a metal having a lower impedance than the through-hole 75, such as copper, aluminum, iron, lead, or the like.

Also, as the bar-shaped conductor member 76, a lead of a coupling capacitor arranged between the power supply terminal and the ground terminal of the motor drive circuit (driving circuit) may be used. In this case, as shown in FIG. 12, the anode terminal 76A of the coupling capacitor C1 is passed through a through hole 75B provided in the power supply pattern, and the cathode terminal 76B of the coupling capacitor C1 is passed through the through hole provided in the ground pattern. Penetrate into 75C. The anode terminal 76A and the cathode terminal 76B of the coupling capacitor C1 are soldered from the surface layer of the circuit board 70 to the back surface of the circuit board 70, as shown in FIG. Further, the coupling capacitor C1 is preferably of a type provided with a stepped rubber explosion-proof valve C1A at its bottom.

The FETs 74A, 74B, 74C, 74D, 74E, and 74F are, for example, sealed in an SOP (Small Outline Package). FIG. 13 shows, for example, the layout and wiring pattern of the FETs 74A and 74D in a circuit block (switching circuit) composed of the FETs 74A and 74D. The pin arrangement of the FET 74A and FET 74D shown in FIG. 13 is, for example, as shown in FIG. A gate is connected to the No. 4 terminal, and a source is connected to the No. 4 terminal. In FIG. 13, the coupling capacitor C1 is connected to the power supply terminals of the circuit block (switching circuit) (the 1st, 2nd, 5th and 6th terminals of the FET 74A from the back side of the mounting surface of the circuit block (switching circuit). ) and the ground terminal (4th terminal of FET 74D). The anode terminal 76A and the cathode terminal 76B of the coupling capacitor C1 may be soldered from the surface layer of the circuit board 70 to the back surface of the circuit board 70 as shown in FIG.

Further, as shown in FIG. 15, at least two circuit blocks (switching circuits) out of the plurality of circuit blocks (switching circuits) have coupling between both power supply terminals and both ground terminals. A capacitor C1 is arranged and the coupling capacitor C1 is shared. FIG. 15 shows two circuit blocks (a plurality of switching circuits), for example, a circuit block (switching circuit) consisting of FET74A and FET74D and a circuit block (switching circuit) consisting of FET74B and FET74E, both of which are connected to power supply terminals. It is an example of an arrangement pattern in which both ground terminals are arranged close to each other. In FIG. 15, the coupling capacitor C1 is indicated by a solid line so as to be arranged on the same surface as the surface of the circuit board 70 on which the FET 74A and the like are mounted. may be arranged on the back side of the surface of Also, the anode terminal 76A and the cathode terminal 76B of the coupling capacitor C1 may be soldered from the surface layer of the circuit board 70 to the back surface of the circuit board 70, as shown in FIG.

As described above, according to the present embodiment, the circuit board 70 is equipped with a drive circuit (motor drive circuit) for driving the load (motor section 12), and the power supply pattern and ground of the drive circuit (motor drive circuit). A through-hole 75 provided in a pattern and a bar-shaped conductor member 76 passing through the through-hole 75 are provided, and the bar-shaped conductor member 76 is soldered from the surface layer to the back surface layer of the circuit board 70. there is That is, the rod-shaped conductor member 76 is soldered from the surface layer to the back surface of the circuit board 70, thereby lowering the impedance. Therefore, since unnecessary heat generation can be prevented, a large current can flow without increasing the board size including the thickness direction of the circuit board 70 .

Further, according to the present embodiment, the bar-shaped conductor member 76 is made of metal with lower impedance than the through-holes 75 . The through-holes 75 in the circuit board 70 are formed by copper plating with a thickness of several tens of μm, and thus have high impedance. , also has excellent thermal conductivity.
Furthermore, as described above, the rod-shaped conductor member 76 is soldered from the surface layer to the back surface of the circuit board 70 . Therefore, since unnecessary heat generation can be prevented by lowering the impedance, a large current can flow without increasing the board size including the thickness direction of the circuit board 70 .

Further, according to this embodiment, the bar-shaped conductor member 76 is the lead of the coupling capacitor C1 arranged between the power supply terminal and the ground terminal of the drive circuit (motor drive circuit). Here, the leads of the coupling capacitor C1 are formed, for example, by welding a CP wire plated with tin of extremely high purity and an aluminum wire. That is, the leads of the coupling capacitor C1 are made of metal with low impedance. Therefore, since the impedance is low, unnecessary heat generation can be prevented, so that a large current can flow without increasing the board size including the thickness direction of the circuit board 70 . In addition, a large current can flow without using a new member and without increasing the board size including the thickness direction of the circuit board 70 .

Further, according to the present embodiment, a stepped rubber explosion-proof valve is provided at the bottom of the coupling capacitor C1. Therefore, even if the leads of the coupling capacitor C1 are soldered over the surface of the circuit board 70 on which the coupling capacitor C1 is mounted, the explosion-proof valve at the bottom of the coupling capacitor C1 will be damaged. I have nothing to do.

Further, according to the present embodiment, the coupling capacitor C1 is arranged close to the power supply terminal and the ground terminal of the drive circuit (motor drive circuit) from the rear side of the mounting surface of the drive circuit (motor drive circuit). . Therefore, as described above, a large current can flow without using a new member and without increasing the board size including the thickness direction of the circuit board 70 . Furthermore, since the coupling capacitor C1 is arranged close to the power supply terminal and the ground terminal of the drive circuit (motor drive circuit) from the rear side of the mounting surface of the drive circuit (motor drive circuit), the current loop is eliminated. It is possible to reduce noise by making it smaller. Also, the arrangement area of the components on the circuit board 70 can be effectively used.

Further, according to the present embodiment, the drive circuit (motor drive circuit) includes a plurality of switching circuits (circuit blocks) each having a power supply terminal and a ground terminal, and among the plurality of switching circuits (circuit blocks), at least , a coupling capacitor C1 is arranged between both power supply terminals and both ground terminals of two switching circuits (circuit blocks). Therefore, the coupling capacitor C1 can be shared by two switching circuits (circuit blocks), and the number of coupling capacitors C1 can be reduced as a whole. In addition, since the number of relatively large coupling capacitors C1 can be reduced, the area for arranging components on the circuit board 70 can be effectively used.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes design within the scope of the gist of the present invention.

10 rotating electric machine 12 motor section 20 housing 60 heat sink 60F recess 60G terminal insertion section (insertion section)
61 first grounding part (grounding part)
61A first board fixing part (board fixing part)
61B second board fixing part (board fixing part)
61C Third board fixing part (board fixing part)
62 stepped portion 63 second grounding portion (grounding portion)
70 circuit board (substrate)
70AR1 First area 70AR2 Second area 71 Non-applied portion 74A FET
74B FETs
74C FETs
74D FETs
74E FETs
74F FETs
75 Through hole 76 Rod-shaped conductor member C1 Coupling capacitor C1A Explosion-proof valve

Claims (3)

a drive circuit for driving a load;
a through hole provided in each of the power supply pattern and the ground pattern of the drive circuit;
a lead of a capacitor penetrating through the through hole and arranged between the power supply pattern and the ground pattern ;
with
The leads of the capacitor are soldered from the surface layer to the back surface of the circuit board ,
The drive circuit is
a first switching element having a power terminal connected to the power pattern;
a second switching element having a ground terminal connected to the ground pattern and connected in series with the first switching element;
with
The capacitor is mounted on the back side of the mounting surface of the first switching element and the second switching element, and the leads of the capacitor are arranged close to each other between the power supply terminal and the ground terminal. A circuit board, characterized in that: 2. The circuit board of claim 1, wherein the capacitor leads have a lower impedance than the through holes. The drive circuit includes a plurality of the first switching elements and the second switching elements,
2. The capacitor according to claim 1 , wherein the capacitor is arranged between the power terminals of the plurality of first switching elements and the ground terminals of the plurality of second switching elements. circuit board.