Electric power shovel, and method of assembling drive unit for driving motor of electric power shovel

Abstract

The present application provides an electric working machine, and a method of assembling a drive unit for driving a motor of the electric working machine, one aspect of which relates to an electric working machine provided with a motor, a circuit substrate, a first semiconductor switch, a second semiconductor switch, a first conductive line, a second conductive line, and a solid metal member. The circuit substrate has a first circuit surface, a second circuit surface, and a through hole. The first semiconductor switch is mounted on the first circuit surface and has a first terminal. The second semiconductor switch is mounted on the second circuit surface and has a second terminal. The first conductive line is disposed on the first circuit surface and electrically connected to the first terminal. The second conductive line is disposed on the second circuit surface and electrically connected to the second terminal. The solid metal member is inserted into the through hole and electrically connected to the first conductive line and the second conductive line.

Description

Technical Field

[0001] This invention relates to an electric work machine equipped with a semiconductor switch. Background Technology

[0002] Japanese Patent No. 5512110 describes an electric power tool that includes: a drill bit, a motor that generates driving force to drive the drill bit, and a drive circuit that drives the motor. The drive circuit includes six switching elements. Three of the six switching elements are mounted on the front surface of the power tool's circuit board. The remaining three switching elements are mounted on the rear surface of the circuit board. Summary of the Invention

[0003] In the aforementioned power tool, to allow current to flow from the switching element on the front surface to the switching element on the rear surface, a via penetrating the power circuit board and printed wiring connecting the via and the switching element are provided. The width of this printed wiring corresponds to the diameter of the via and is relatively narrow. Consequently, the inductance of the printed wiring is relatively large. Therefore, a relatively large surge voltage is generated in the current path with the switching action of the switching element. Accordingly, it is necessary to increase the rated voltage of the switching element. Generally, when the rated voltage of the switching element increases, the on-resistance of the switching element also increases. When the on-resistance increases, the heat generated during the conduction of the switching element also increases.

[0004] One aspect of the present invention aims to reduce the inductance of the current path on the circuit board of an electric work machine.

[0005] In this invention, the terms "first," "second," etc., are merely intended to distinguish elements from each other, and are not intended to limit the order or number of elements. Therefore, the first element can be called the second element, and similarly, the second element can be called the first element. In addition, the first element can be present without the second element, and similarly, the second element can be present without the first element.

[0006] One aspect of the present invention provides an electric work machine comprising: a motor, a circuit board, a first semiconductor switch, a second semiconductor switch, a first conductive line, a second conductive line, and a solid metal component. The motor is configured to receive power from a power source for driving. The circuit board has: a first circuit surface, a second circuit surface opposite to the first circuit surface, and a through-hole. The first semiconductor switch is electrically connected to the power source and the motor, and is located on the first circuit surface, having a first terminal. The second semiconductor switch is electrically connected to the power source and the motor, and is located on the second circuit surface, and unlike the first semiconductor switch, has a second terminal. The first conductive line is disposed on the first circuit surface and is electrically connected to the first terminal. The second conductive line is disposed on the second circuit surface and is electrically connected to the second terminal. The solid metal component is inserted into the through-hole and is electrically connected to the first and second conductive lines.

[0007] In this electric work machine, the first terminal is electrically connected to the second terminal via a solid metal component inserted into a through-hole. Since the width of the metal component can be greater than the diameter of the through-hole, the width of the first and second conductive lines can be increased. Furthermore, the inductance of the first and second conductive lines can be reduced. Additionally, since the metal component is solid, its inductance is less than that of the through-hole. Therefore, the inductance of the current path on the circuit board can be reduced, thereby suppressing surge voltages generated by the switching operation of the first and second semiconductor switches. Furthermore, the rated voltage of the first and second semiconductor switches can be suppressed, thereby suppressing the heat generated by the first and second semiconductor switches. Moreover, by suppressing the heat generated by the first and second semiconductor switches, the components on the circuit board and the heat dissipation components of the electric work machine can be miniaturized. This further enables the miniaturization of the electric work machine.

[0008] Another aspect of the present invention provides a method for assembling a drive unit for driving a motor of an electric work machine. The method includes the following steps: mounting a first semiconductor switch of the drive unit on a first circuit surface of a circuit board of the drive unit, the first circuit surface having a first conductive line; mounting a second semiconductor switch of the drive unit, different from the first semiconductor switch, on a second circuit surface of the circuit board opposite to the first circuit surface, the second circuit surface having a second conductive line; inserting a solid metal component into a through-hole in the circuit board; electrically connecting a first terminal of the first semiconductor switch to the first conductive line; connecting a second terminal of the second semiconductor switch to the second conductive line; electrically connecting the first conductive line; and electrically connecting the second conductive line to the solid metal component.

[0009] According to this method, the inductance of the current path on the circuit board of the electric machine can be reduced, thereby suppressing the surge voltage generated by the switching action of the first and second semiconductor switches. Attached Figure Description

[0010] Figure 1 This is a diagram showing the appearance of the electric work machine according to this embodiment.

[0011] Figure 2 This is a diagram showing the electrical configuration of the electric work machine according to this embodiment.

[0012] Figure 3 This is a top view showing the first circuit surface of the circuit board equipped with the drive circuit according to this embodiment.

[0013] Figure 4 This is a diagram showing the second circuit surface of the circuit board involved in this embodiment.

[0014] Figure 5 This is a diagram showing the appearance of the metal component inserted into the circuit board according to this embodiment.

[0015] Figure 6 This diagram shows the electrical connection between the source terminal of the first semiconductor switch and the drain terminal of the fourth semiconductor switch according to this embodiment.

[0016] Figure 7 This is a cross-sectional view of the circuit board involved in this embodiment.

[0017] Figure 8 This is a diagram showing a modified example of the cross-section of the circuit board involved in this embodiment.

[0018] Figure 9 This is a partial cross-sectional view showing the drive unit involved in other embodiments. Detailed Implementation

[0019] [Summary of Implementation Methods]

[0020] One embodiment may provide an electric work machine having at least one of the following features:

[0021] • Feature 1: It is configured as a motor that receives power from a power source for driving;

[0022] • Feature 2: A circuit board having a first circuit surface, a second circuit surface on the opposite side of the first circuit surface, and a through hole;

[0023] Feature 3: A first semiconductor switch electrically connected to the power supply and the motor and mounted on the first circuit surface;

[0024] Feature 4: The first semiconductor switch has a first terminal;

[0025] Feature 5: A second semiconductor switch that is electrically connected to the power supply and the motor and is mounted on the second circuit surface and is different from the first semiconductor switch;

[0026] Feature 6: The second semiconductor switch has a second terminal;

[0027] Feature 7: A first conductive line disposed on the first circuit surface and electrically connected to the first terminal;

[0028] Feature 8: A second conductive line disposed on the second circuit surface and electrically connected to the second terminal;

[0029] Feature 9: A solid metal component inserted into the through hole;

[0030] Feature 10: Solid metal components are electrically connected to the first conductive line and the second conductive line.

[0031] In the electric work machine having at least features 1 to 10, the first terminal is electrically connected to the second terminal via a solid metal component inserted into a through-hole. Since the width of the metal component can be greater than the diameter of the through-hole, the width of the first and second conductive lines can be increased. Furthermore, the inductance of the first and second conductive lines can be reduced. Additionally, since the metal component is solid, its inductance is less than that of the through-hole. Therefore, the inductance of the current path on the circuit board can be reduced, thereby suppressing surge voltages generated during the switching operation of the first and second semiconductor switches. Furthermore, the rated voltage of the first and second semiconductor switches can be suppressed, thereby suppressing the heat generated by the first and second semiconductor switches. Moreover, by suppressing the heat generated by the first and second semiconductor switches, the components on the circuit board and the heat dissipation components of the electric work machine can be miniaturized. Furthermore, the electric work machine can be miniaturized.

[0032] Examples of solid metal components include: pre-manufactured solid metal components, and conductive pastes or solders that are filled in through-holes and cured or sintered. Examples of conductive pastes include metal pastes, and more specifically, gold pastes, silver pastes, copper pastes, and aluminum pastes.

[0033] In addition to having at least one of the features 1 to 10 described above, or alternatively, a certain embodiment may also have the following features.

[0034] Feature 11: The first semiconductor switch corresponds to the high-side switch of the drive circuit that drives the motor;

[0035] Feature 12: The second semiconductor switch corresponds to the low-side switch of the drive circuit;

[0036] • Feature 13: Terminal 1 is positioned opposite Terminal 2 across the circuit board.

[0037] In the electric work machine having at least features 1 to 13, the first terminal of the high-side switch is positioned opposite the second terminal of the low-side switch across the circuit board. This reduces the length of the first and second conductive lines in the current path from the first terminal to the second terminal. Furthermore, it further reduces the inductive component of the circuit board, thereby further suppressing surge voltages generated during the switching operations of the first and second semiconductor switches.

[0038] In addition to having at least one of the features 1 to 13 described above, or alternatively, a certain embodiment may also have the following features.

[0039] Feature 14: The first semiconductor switch and the second semiconductor switch are field-effect transistors;

[0040] Feature 15: The first terminal is the source terminal of the first semiconductor switch;

[0041] Feature 16: The second terminal is the drain terminal of the second semiconductor switch.

[0042] In an electric work machine having at least features 1 to 10 and 14 to 16, the source terminal of the high-side switch can be connected to the drain terminal of the low-side switch via first and second conductive lines whose lengths have been suppressed.

[0043] In addition to having at least one of the features 1 to 16 described above, or alternatively, a certain embodiment may also have the following features.

[0044] Feature 17: The solid metal component includes: a first portion protruding from the through hole and a second portion received within the through hole;

[0045] Feature 18: The through hole has a first length in a specified direction along the first circuit plane;

[0046] Feature 19: The first part has a second length that is greater than the first length in the specified direction;

[0047] Feature 20: The second part has a third length that is smaller than the first length in the specified direction.

[0048] In an electric workpiece having at least features 1 to 10 and 17 to 20, the second length is greater than the first length, and the third length is less than the first length. Accordingly, the second part is housed in a through hole, and a portion of the lower surface of the first part abuts against the first circuit surface. Therefore, it is possible to prevent solid metal parts from falling off the circuit board.

[0049] In addition to having at least one of the features 1 to 20 described above, or alternatively, a certain embodiment may also have the following features.

[0050] Feature 21: The through hole extends along the end of the first semiconductor switch.

[0051] In the electric working machine having at least features 1 to 10, 21, the through-hole extends along the end of the first semiconductor switch. This allows the through-hole to be positioned close to the first and second semiconductor switches. Furthermore, it further shortens the first and second conductive lines in the current path from the first terminal to the second terminal, and further suppresses surge voltages generated during the switching operation of the first and second semiconductor switches.

[0052] In addition to having at least one of the features 1 to 21 described above, or alternatively, a certain embodiment may also have the following features.

[0053] Feature 22: The through hole has a cuboid shape.

[0054] According to the electric working machine having at least features 1 to 10 and 21 to 22, it is possible to suppress the enlargement of the circuit board and increase the volume of the metal parts, thereby reducing the inductance of the metal parts.

[0055] In addition to having at least one of the features 1 to 22 described above, or alternatively, a certain embodiment may also have the following features.

[0056] Feature 23: The first semiconductor switch and the second semiconductor switch have a cuboid shape;

[0057] Feature 24: The short side direction of the first semiconductor switch is consistent with the short side direction of the second semiconductor switch;

[0058] Feature 25: The long side of the through hole is aligned with the short side of the first semiconductor switch and the second semiconductor switch.

[0059] According to the electric working machine having at least features 1 to 10 and 21 to 25, it is possible to suppress the enlargement of the circuit board and reduce the inductance of the first and second conductive lines and metal components.

[0060] In addition to having at least one of the features 1 to 25 described above, or alternatively, a certain embodiment may also have the following features.

[0061] Feature 26: Solder resist is applied between the end and the through hole on the first conductive line;

[0062] In an electric work machine having at least features 1 to 10, 21, and 26, solder resist is applied between the end of the first semiconductor switch and the through hole. This prevents contact between the solder that bonds the solid metal component to the first conductive line and the solder that bonds the first terminal to the first conductive line.

[0063] At least one of the first semiconductor switch and the second semiconductor switch may include a surface mount package, examples of which include, but are not limited to, top surface cooled packages and double-sided cooled packages.

[0064] Examples of top-side cooling packages include, but are not limited to, TO-Leaded Top-side cooling (TOLT) packages. Examples of double-side cooling packages include, but are not limited to, Double-side-cooling Small Outline Package (DSOP). Examples of the first and second semiconductor switches include, but are not limited to, metal-oxide-semiconductor field-effect transistors (MOSFETs), junction field-effect transistors (JFETs), insulated-gate bipolar transistors (IGBTs), bipolar transistors, solid-state relays (SSRs), and thyristors.

[0065] Examples of electric work machines include: various electrical equipment used in amateur woodworking, manufacturing, gardening, construction, and other work sites. Specifically, this includes: power tools for stonemasonry, metalworking, and woodworking; gardening work machines; and tools for preparing the work site environment. More specifically, this includes: electric blowers, electric hammers, electric hammer drills, electric drills, electric screwdrivers, electric wrenches, electric grinders, electric polishers, electric circular saws, electric reciprocating saws, electric wire saws, electric cutting tools, electric chainsaws, electric planers, electric nail machines (including riveting machines), electric lawn mowers, electric lawn trimmers, electric hedge trimmers, electric lawn mowers, electric cleaners, electric sprayers, electric spreaders, electric dust collectors, electric bicycles (or e-bikes), and battery-powered handcarts, but is not limited to these.

[0066] One embodiment may provide a method for assembling a drive unit for driving a motor of an electric work machine, having at least any one of the following features:

[0067] Feature 27: The first semiconductor switch of the driving unit is mounted on the first circuit surface of the circuit board of the driving unit;

[0068] Feature 28: The first circuit surface has a first conductive line;

[0069] Feature 29: A second semiconductor switch, which is different from the first semiconductor switch, is mounted on a second circuit surface on the opposite side of the first circuit surface of the circuit board.

[0070] Feature 30: The second circuit surface has a second conductive line;

[0071] Feature 31: A solid metal component is inserted into a through hole in the circuit board;

[0072] Feature 32: The first terminal of the first semiconductor switch is electrically connected to the first conductive line;

[0073] Feature 33: The second terminal of the second semiconductor switch is electrically connected to the second conductive line;

[0074] Feature 34: Electrically connecting the first conductive line and the second conductive line to a solid metal component.

[0075] According to the method having at least features 27 to 34, the inductance of the circuit board of the electric work machine can be reduced, thereby suppressing the surge voltage generated by the switching action of the first and second semiconductor switches.

[0076] In one embodiment, features 1 to 34 described above can also be combined in any combination.

[0077] In one embodiment, any one of the features 1 to 34 described above may be removed.

[0078] [Specific exemplary implementation methods]

[0079] The following describes a specific exemplary embodiment. This specific exemplary embodiment provides an electric work machine 1 in the form of an electric chainsaw. An electric chainsaw is a type of gardening tool. However, such an electric work machine 1 is merely an example, and the present invention can be applied to all types of electric work machines.

[0080] (1. First embodiment)

[0081] <1-1. Composition of Electric Working Machines>

[0082] like Figure 1As shown, the electric work machine 1 includes a housing 2. The housing 2 is formed of synthetic resin. The housing 2 houses the motor 20 inside. The housing 2 also houses the drive unit 25 inside. The drive unit 25 includes: a circuit board 11 described later, and a drive circuit 21 mounted on the circuit board 11.

[0083] The terms "up," "down," "front," "back," "left," and "right" used in the following description are merely for the purpose of facilitating understanding of the structure of the electric work machine 1 and its components, and are not intended to limit the orientation of the electric work machine 1 and its components. The electric work machine 1 and its components can be configured in all directions.

[0084] The electric work machine 1 includes a guide rod 9. The guide rod 9 is a plate-shaped component. The guide rod 9 protrudes from the outer casing 2 toward the front of the electric work machine 1.

[0085] The electric work machine 1 includes a chainsaw 9a as a tool. The chainsaw 9a includes multiple interconnected blades. The chainsaw 9a is detachably mounted on the periphery of the guide rod 9. The chainsaw 9a is connected to the rotor shaft (not shown) of the motor 20 via a power transmission mechanism (not shown). The power transmission mechanism includes a sprocket (not shown) configured for mounting the chainsaw 9a.

[0086] Therefore, by driving the motor 20, the chainsaw 9a moves around the periphery of the guide rod 9. The electric workpiece 1 can cut the workpiece by means of the moving chainsaw 9a.

[0087] The electric work machine 1 includes a battery assembly 5. In this embodiment, the battery assembly 5 protrudes upward from the rear of the outer casing 2. A battery pack 12 is detachably mounted to the battery assembly 5. The battery pack 12 can be mounted on the rear end face of the battery assembly 5. The battery pack 12 includes a secondary battery. In this embodiment, although the secondary battery is a lithium-ion battery, it is not limited to lithium-ion batteries. By being mounted to the battery assembly 5, the battery pack 12 can supply DC power to the electric work machine 1.

[0088] In other embodiments, the electric work machine 1 may replace the battery assembly 5 with a power cord. The electric work machine 1 may also receive AC power from a commercial power source or other AC power source via the power cord. The AC power received from the AC power source may also be converted into DC power or AC power with different characteristics within the electric work machine 1.

[0089] The electric work machine 1 is equipped with a hand guard 4. The hand guard 4 protrudes upward from the front of the outer casing 2.

[0090] The electric work machine 1 has a side handle 3A and a top handle 3B behind the hand guard 4. Either the side handle 3A or the top handle 3B may be omitted. The side handle 3A and the top handle 3B are made of synthetic resin.

[0091] The side handle 3A is a tubular component. The side handle 3A protrudes from the left side of the housing 2 toward the left. Therefore, the user of the electric work machine 1 can hold the side handle 3A with their left hand from the rear of the electric work machine 1.

[0092] The top handle 3B protrudes upward from the upper part of the housing 2. The rear end of the top handle 3B is connected to the battery assembly 5, thereby forming a space between the top handle 3B and the housing 2. Thus, the user can insert their fingers into this space to hold the top handle 3B.

[0093] The electric work machine 1 has a trigger switch 7 located below the top handle 3B. The trigger switch 7 is operated by the user (e.g., pulled) to drive the motor 20. When the trigger switch 7 is pulled upwards by the user, the motor 20 is driven. Conversely, when the operation of the trigger switch 7 is released, the drive of the motor 20 is stopped.

[0094] The electric work machine 1 has a trigger locking stop 8 above the top handle 3B. When the user presses the trigger locking stop 8 downwards, the lock of the trigger switch 7 is released.

[0095] <1-2. Control Unit>

[0096] like Figure 2 As shown, the electric work machine 1 has a control unit 10.

[0097] The control unit 10 receives DC power from the battery 12a in the battery pack 12 to control the motor 20 by driving or stopping the chainsaw 9a. In this embodiment, the motor 20 is a 3-phase brushless DC motor. In other embodiments, the motor 20 may also be a single-phase brushless DC motor, a 2-phase brushless DC motor, a 4-phase or higher brushless DC motor, a brushed motor, an AC motor, or a stepper motor.

[0098] The control unit 10 includes: a drive unit 25 with a drive circuit 21, a gate circuit 22, a control circuit 23, and a regulator 24.

[0099] The drive circuit 21 is configured to: (i) receive DC motor current from the battery 12a; (ii) convert the received DC motor current into three-phase AC motor current (i.e., U-phase, V-phase, and W-phase motor current); and (iii) supply the three-phase AC motor current to the three-phase windings (not shown) of the motor 20. Specifically, the drive circuit 21 is a three-phase full-bridge inverter circuit equipped with semiconductor switches Q1 to Q6 (first to sixth phases). In other embodiments, the drive circuit 21 may be a single-phase, two-phase, or four-phase or more full-bridge inverter circuit, or a half-bridge inverter circuit.

[0100] Specifically, the first to sixth semiconductor switches Q1 to Q6 are FETs. More specifically, the first to sixth semiconductor switches Q1 to Q6 are N-channel MOSFETs. In other embodiments, at least one of the first to sixth semiconductor switches Q1 to Q6 may also be: a P-channel MOSFET, a JFET, an IGBT, a bipolar transistor, an SSR, or a thyristor.

[0101] In drive circuit 21, semiconductor switches Q1 to Q3 (first to third) are high-side switches. These switches are connected to terminals U, V, and W of motor 20 and power line Lp. Power line Lp is connected to the positive terminal of battery 12a. In drive circuit 21, semiconductor switches Q4 to Q6 (fourth to sixth) are low-side switches. These switches are connected to terminals U, V, and W of motor 20 and ground line Ln. Ground line Ln is connected to the negative terminal of battery 12a.

[0102] Semiconductor switches Q1 to Q6, numbered 1 to 6, each have gate terminals 41, 51, 61, 71, 81, and 91; drain terminals 42, 52, 62, 72, 82, and 92; and source terminals 43, 53, 63, 73, 83, and 93. The gate terminals 41, 51, 61, 71, 81, and 91 of semiconductor switches Q1 to Q6 are connected to gate circuit 22. The drain terminals 42, 52, and 62 of semiconductor switches Q1 to Q3, numbered 1 to 3, are connected to power line Lp. The source terminals 73, 83, and 93 of semiconductor switches Q4 to Q6, numbered 4 to 6, are connected to ground line Ln. The source terminal 43 of semiconductor switch Q1 is connected to the drain terminal 72 of semiconductor switch Q4 and the U phase of motor 20. The source terminal 53 of the second semiconductor switch Q2 is connected to the drain terminal 82 of the fifth semiconductor switch Q5 and the V phase of the motor 20. The source terminal 63 of the third semiconductor switch Q3 is connected to the drain terminal 92 of the sixth semiconductor switch Q6 and the W phase of the motor 20.

[0103] Gate circuit 22 turns semiconductor switches Q1 to Q6 (number 1 to 6) on or off according to the control signal output from control circuit 23, supplying three-phase AC motor current to the three-phase windings of motor 20. As a result, motor 20 rotates.

[0104] The control circuit 23 includes a microcomputer (or microcontroller, or microprocessor) not shown. In other embodiments, the control circuit 23 may include an additional microcomputer. Furthermore, in other embodiments, instead of a microcomputer, or in addition to the above, the control circuit 23 may also include: a graphics processing unit (GPU), wiring logic, an application-specific integrated circuit (ASIC), an application-specific general-purpose component (ASSP), a programmable logic device (PLD) (e.g., a field-programmable gate array (FPGA), etc.), discrete electronic components, and / or combinations thereof.

[0105] The regulator 24 is configured to: (i) receive DC power from the battery 12a, and (ii) generate a power supply voltage Vcc. The power supply voltage Vcc is supplied to the internal circuitry of the control unit 10, which includes the control circuit 23.

[0106] The control unit 10 also includes a load switch Q7 and a bootstrap circuit 26. The load switch Q7 is configured between the battery 12a and the drive circuit 21 on the power line Lp to protect the drive circuit 21 and / or the motor 20. The load switch Q7 is a semiconductor switch. Specifically, the load switch Q7 is an N-channel MOSFET. In other embodiments, the load switch Q7 may also be a P-channel MOSFET, JFET, IGBT, bipolar transistor, or SSR. Furthermore, in other embodiments, the load switch Q7 may also be a mechanical relay. Moreover, the gate terminal of the load switch Q7 is connected to the control circuit 23 via the bootstrap circuit 26. When the motor 20 is allowed to drive, the load switch Q7 remains in the ON state. The motor current flowing to the load switch Q7 may be greater than the motor current flowing to the first to sixth semiconductor switches Q1 to Q6, respectively. The voltage applied to the load switch Q7 may be greater than the voltage applied to the first to sixth semiconductor switches Q1 to Q6. Therefore, the rated voltage and rated current of the load switch Q7 are higher than the rated voltage and rated current of the first to sixth semiconductor switches Q1 to Q6, respectively.

[0107] The drive circuit 21 includes a first thermistor 27 and a second thermistor 29. The first thermistor 27 is positioned near the first to third semiconductor switches Q1 to Q3 and measures the temperature of the switches. The first thermistor 27 sends a temperature detection signal indicating the measured temperature to the control circuit 23. The second thermistor 29 is positioned near the fourth to sixth semiconductor switches Q4 to Q6 and measures the temperature of the switches. The second thermistor 29 sends a temperature detection signal indicating the measured temperature to the control circuit 23.

[0108] <1-3. Drive Unit>

[0109] <1-3-1. Example>

[0110] Reference Figures 3-7 The driving unit 25 is described below. The driving unit 25 includes: a circuit board 11, a driving circuit 21 mounted on the circuit board 11, four elastic members 35, two metal plates 100, heat dissipation members 200 and 500, four externally threaded members 400, three metal members 600, first to third printed wirings 511 to 513, and fourth to sixth printed wirings 521 to 523. Furthermore, Figure 3 as well as Figure 4 The two metal plates 100, heat dissipation components 200 and 500, and four external threaded components 400 are transparently displayed. In fact, the upper surface of the driving circuit 21 on the circuit board 11 is covered by the two metal plates 100 and heat dissipation components 200 and 500.

[0111] The circuit board 11 is a printed circuit board (PCB). The circuit board 11 has a rectangular planar shape. In other embodiments, the circuit board 11 may also have a planar shape other than a rectangle. The circuit board 11 includes a first circuit surface 11A and a second circuit surface 11B. The second circuit surface 11B is located on the opposite side of the first circuit surface 11A.

[0112] The drive circuit 21 includes: first to sixth semiconductor switches Q1 to Q6, first and second thermistors 27 and 29, U-phase terminal 45, V-phase terminal 55, W-phase terminal 65, three metal parts 600, first to third printed wiring 511 to 513, and fourth to sixth printed wiring 521 to 523.

[0113] Semiconductor switches Q1 to Q6 are surface-mount type. That is, semiconductor switches Q1 to Q6 have surface-mount packages. More specifically, semiconductor switches Q1 to Q6 have top surface cooled packages, and more specifically, they have TOLT packages. Semiconductor switches Q1 to Q6 are of the same type, but are not limited to the same type.

[0114] Semiconductor switches Q1 to Q6 are each packaged in a plate shape, comprising: (i) one corresponding end among first ends 46A, 56A, 66A, 76A, 86A, and 96A; and (ii) one corresponding end among second ends 46B, 56B, 66B, 76B, 86B, and 96B, respectively, opposite to the first ends 46A, 56A, 66A, 76A, 86A, and 96A. Drain terminals 42, 52, 62, 72, 82, and 92 of semiconductor switches Q1 to Q6 protrude from the first ends 46A, 56A, 66A, 76A, 86A, and 96A, respectively. The gate terminals 41, 51, 61, 71, 81, and 91 of the first to sixth semiconductor switches Q1 to Q6 protrude from the second end 46B, 56B, 66B, 76B, 86B, and 96B, respectively. The source terminals 43, 53, 63, 73, 83, and 93 of the first to sixth semiconductor switches Q1 to Q6 protrude from the second end 46B, 56B, 66B, 76B, 86B, and 96B, respectively.

[0115] The first semiconductor switch Q1 includes: (i) a first metal surface 46, and (ii) a first mounting surface 48 located on the opposite side of the first metal surface 46. The second semiconductor switch Q2 includes: (i) a second metal surface 56, and (ii) a second mounting surface 58 located on the opposite side of the second metal surface 56. The third semiconductor switch Q3 includes: (i) a third metal surface 66, and (ii) a third mounting surface 68 located on the opposite side of the third metal surface 66. The fourth semiconductor switch Q4 includes: (i) a fourth metal surface 76, and (ii) a fourth mounting surface 78 located on the opposite side of the fourth metal surface 76. Figure 3 , 4 (Not shown in the figure). The fifth semiconductor switch Q5 includes: (i) a fifth metal surface 86, and (ii) a fifth mounting surface 88 located on the opposite side of the fifth metal surface 86. Figure 3 , 4 (Not shown in the figure). The sixth semiconductor switch Q6 includes: (i) a sixth metal surface 96, and (ii) a sixth mounting surface 98 located on the opposite side of the sixth metal surface 96. Figure 3 , 4 (Not shown in the image).

[0116] The first to sixth metal surfaces 46, 56, 66, 76, 86, and 96 each include a metal plate (metal pad) that is surface-bonded to the package of one of the first to sixth semiconductor switches Q1 to Q6. The metal plate may be made of aluminum, copper, silver, or gold, or be made of aluminum, copper, silver, or gold. The first to sixth semiconductor switches Q1 to Q6 are mounted on the first circuit surface 11A with the first to sixth mounting surfaces 48, 58, 68, 78, 88, and 98 facing the first circuit surface 11A. The first to sixth mounting surfaces 48, 58, 68, 78, 88, and 98 are soldered to the first circuit surface 11A.

[0117] like Figure 3 As shown, the first to third semiconductor switches Q1 to Q3 are arranged in a row along the left and right direction on the first circuit surface 11A. The first to third semiconductor switches Q1 to Q3 are configured such that the first ends 46A, 56A, and 66A are the front side and the second ends 46B, 56B, and 66B are the rear side.

[0118] like Figure 4 As shown, semiconductor switches Q4 to Q6, numbered 4 to 6, are arranged in a row along the left-right direction on the second circuit surface 11B. Semiconductor switches Q4 to Q6 are respectively positioned opposite semiconductor switches Q1 to Q3, numbered 1 to 3, separated by the circuit board 11. Semiconductor switches Q4 to Q6 are configured such that the second ends 76B, 86B, and 96B are the front side, and the first ends 76A, 86A, and 96A are the rear side.

[0119] Therefore, the source terminal 43 of the first semiconductor switch Q1 is disposed opposite to the drain terminal 72 of the fourth semiconductor switch Q4, separated by the circuit board 11. The source terminal 53 of the second semiconductor switch Q2 is disposed opposite to the drain terminal 82 of the fifth semiconductor switch Q5, separated by the circuit board 11. The source terminal 63 of the third semiconductor switch Q3 is disposed opposite to the drain terminal 92 of the sixth semiconductor switch Q6, separated by the circuit board 11.

[0120] The circuit board 11 includes first to third through holes 501 to 503 penetrating the circuit board 11. The first to third through holes 501 to 503 are slits extending in a left-right direction. The first to third through holes 501 to 503 are disposed near the source terminals 43, 53, 63 and the gate terminals 41, 51, 61 (for example, within 10 mm of these terminals) along the second ends 46B, 56B, 66B of the first to third semiconductor switches Q1 to Q3. Therefore, the first to third through holes 501 to 503 are disposed near the drain terminals 72, 82, 92 along the first ends 76A, 86A, 96A of the fourth to sixth semiconductor switches Q4 to Q6.

[0121] The length of each of the first to third substrate through-holes 501 to 503 in the left-right direction is approximately equal to the width (e.g., 10 mm or more) of at least one corresponding semiconductor switch among the first to sixth semiconductor switches Q1 to Q6. In other embodiments, the planar shape of each of the first to third substrate through-holes 501 to 503 can be an ellipse, a circle, or a polygon.

[0122] Metal components 600 are respectively inserted into one corresponding through-hole of the first to third substrate through-holes 501 to 503. Figure 3 as well as Figure 4 For convenience, the metal component 600 is inserted into the first and second substrate through holes 501 and 502. The metal component 600 is then removed from the third substrate through hole 503. In fact, the first to third substrate through holes 501 to 503 are all filled with the metal component 600.

[0123] Metal component 600 comprises or is made of a metal with high conductivity. Examples of metals include copper, silver, gold, and aluminum. Metal component 600 is a pre-manufactured solid component. In other embodiments, at least one of the three metal components 600 may be a conductive paste that is filled in the through-holes 501-503 of the first to third substrates and cured or sintered. The conductive paste is a metal paste, and more specifically, may be gold paste, silver paste, copper paste, or aluminum paste. Furthermore, in other embodiments, at least one of the three metal components 600 may be solder that is filled in the through-holes 501-503 of the first to third substrates and cured.

[0124] like Figure 5As shown, the metal component 600 includes a first portion 610 and a second portion 620. The first portion 610 is cuboid in shape. On any horizontal plane, the length of the long side of the first portion 610 is greater than the length in the left-right direction of each of the through holes 501-503 of the first to third substrates. On any horizontal plane, the length of the short side of the first portion 610 is slightly less than the length in the front-back direction of each of the through holes 501-503 of the first to third substrates, but it can be the same or larger. The second portion 620 is cuboid in shape. The second portion 620 is connected to the lower part of the first portion 610 such that the long side of the second portion 620 aligns with the long side of the first portion 610. The length of the long side of the second portion 620 is slightly less than the length in the left-right direction of each of the through holes 501-503 of the first to third substrates. That is, the width of the second portion 620 (e.g., 10 mm) is sufficiently greater than the diameter of the through hole (e.g., 0.5 mm). Here, on any horizontal plane, the width is equivalent to the length in the direction orthogonal to the direction of current flow, and the orthogonal direction is equivalent to the long side direction. The length of the short side of the second part 620 is slightly less than the length of the through holes 501-503 of the first to third substrates in the front-back direction. The height of the second part 620 is approximately equal to the thickness of the circuit board 11. The metal components 600 each have a T-shaped vertical cross-section, but may also have other shapes of vertical cross-sections.

[0125] Metal components 600 are inserted from the first circuit surface 11A toward the second circuit surface 11B into corresponding through holes 501 to 503 of the first to third substrates. A first portion 610 hooks onto the first circuit surface 11A, preventing the corresponding metal component 600 from falling off the circuit board 11. A second portion 620 is housed within the first to third through holes 501 to 503.

[0126] like Figure 3 as well as Figure 6 As shown, the first to third printed wirings 511 to 513 are respectively disposed between one corresponding source terminal of the first to third semiconductor switches Q1 to Q3 (43, 53, 63) and one corresponding substrate through-hole of the first to third substrate through-holes 501 to 503. Furthermore, the first to third printed wirings 511 to 513 are also disposed on the rear side of one corresponding substrate through-hole of the first to third substrate through-holes 501 to 503.

[0127] Printed wiring (or lines or conductive tracks) is formed from a metal foil with high conductivity. More specifically, the metal foil includes copper, silver, or gold. Through-holes are filled with metal or plated with metal. This metal includes copper, silver, or gold.

[0128] Printed wirings 511-513 (first to third) are electrically connected to source terminals 43, 53, and 63, respectively. Specifically, printed wirings 511-513 are soldered to source terminals 43, 53, and 63, respectively. In addition, printed wirings 511-513 are electrically connected to a corresponding metal component 600. Specifically, printed wirings 511-513 are soldered to the first portion 610 of a corresponding metal component 600. The metal component 600 is electrically connected to a corresponding terminal among the U-phase terminal 45, V-phase terminal 55, and W-phase terminal 65 via a corresponding printed wiring from printed wirings 511-513.

[0129] Solder resist 15 is applied between the source terminals 43, 53, and 63 and the three metal components 600, and on the first to third printed wirings 511 to 513. Additionally, solder resist 15 is applied to the rear side of the three metal components 600, and on the first to third printed wirings 511 to 513. No solder resist 15 is applied to the underside of the first to third mounting surfaces 48, 58, and 68. The lower ends of the gate terminals 41, 51, and 61, the drain terminals 42, 52, and 62, and the source terminals 43, 53, and 63 are located slightly higher than the corresponding mounting surface among the first to third mounting surfaces 48, 58, and 68. When solder resist 15 is applied to the underside of the first to third mounting surfaces 48, 58, and 68, the brazing of the gate terminals 41, 51, and 61, the drain terminals 42, 52, and 62, and the source terminals 43, 53, and 63 becomes difficult.

[0130] like Figure 4 as well as Figure 6 As shown, the 4th to 6th printed wirings 521 to 523 are respectively disposed between one corresponding drain terminal of the 4th to 6th semiconductor switches Q4 to Q6 (72, 82, 92) and one corresponding substrate through-hole of the 1st to 3rd substrate through-holes 501 to 503. Furthermore, the 4th to 6th printed wirings 521 to 523 are also disposed on the rear side of one corresponding substrate through-hole of the 1st to 3rd substrate through-holes 501 to 503.

[0131] Printed wirings 521-523, numbered 4 to 6, are electrically connected to drain terminals 72, 82, and 92, respectively. Specifically, printed wirings 521-523 are soldered to drain terminals 72, 82, and 92, respectively. Additionally, printed wirings 521-523 are electrically connected to a corresponding metal component of the metal components 600. Specifically, printed wirings 521-523 are soldered to the second portion 620 of a corresponding metal component of the metal components 600. The metal components 600 are electrically connected to a corresponding terminal of the U-phase terminal 45, V-phase terminal 55, and W-phase terminal 65 via a corresponding printed wiring from printed wirings 521-523.

[0132] Solder resist 15 is applied between the drain terminals 72, 82, and 92 and the three metal components 600, and on the 4th to 6th printed wirings 521 to 523. Additionally, solder resist 15 is applied to the rear side of the three metal components 600, and on the 4th to 6th printed wirings 521 to 523. No solder resist 15 is applied to the underside of the 4th to 6th mounting surfaces 78, 88, and 98.

[0133] The source terminals 43, 53, and 63 of the first to third semiconductor switches Q1 to Q3 are each electrically connected to a corresponding drain terminal 72, 82, and 92 of the fourth to sixth semiconductor switches Q4 to Q6 via a corresponding metal component 600. This minimizes the length of the printed wiring from the source terminals 43, 53, and 63 to their respective drain terminals 72, 82, and 92. Consequently, the inductive component of the drive circuit 21 is reduced. This suppresses surge voltages accompanying the switching operation of the first to sixth semiconductor switches Q1 to Q6, thereby reducing the rated voltage of the first to sixth semiconductor switches Q1 to Q6. Furthermore, heat generated by the first to sixth semiconductor switches Q1 to Q6 can be suppressed. This allows for the removal or reduction of at least one of the metal plate 100 and heat dissipation components 200 and 500. Additionally, it enables the miniaturization of electronic components on the circuit board 11. Therefore, the drive unit 25 can be miniaturized, thereby reducing costs.

[0134] Without using the metal component 600, source terminals 43, 53, and 63 can be electrically connected to drain terminals 72, 82, and 92, respectively, using printed wiring and vias. However, when connecting these terminals using printed wiring and vias, the printed wiring becomes longer, and the inductive component of the printed wiring increases. As a result, the surge voltage accompanying the switching operation of semiconductor switches Q1 to Q6 increases.

[0135] A first thermistor 27 is disposed on a first circuit surface 11A between a first semiconductor switch Q1 and a second semiconductor switch Q2. A second thermistor 29 is disposed on a second circuit surface 11B between a fourth semiconductor switch Q4 and a fifth semiconductor switch Q5. In this embodiment, the first to sixth semiconductor switches Q1 to Q6 each have a first height H1. The first and second thermistors 27 and 29 each have a second height H2. The first height H1 and the second height H2 correspond to the lengths in the vertical direction, and the second height H2 is greater than the first height H1.

[0136] The U-phase terminal 45 is disposed on the rear side of the through-hole 501 in the first substrate on the first circuit surface 11A. The source terminal 43 of the first semiconductor switch Q1, the drain terminal 72 of the fourth semiconductor switch Q4, the metal component 600 in the through-hole 501 of the first substrate, and the U-phase terminal 45 are electrically connected to each other. The drain terminal 42 of the first semiconductor switch Q1 is electrically connected to the power line Lp via printed wiring (not shown) and / or vias (not shown) on the first circuit surface 11A. The source terminal 73 of the fourth semiconductor switch Q4 is electrically connected to the ground line Ln via printed wiring (not shown) and / or vias (not shown) on the second circuit surface 11B.

[0137] The V-phase terminal 55 is disposed on the first circuit surface 11A behind the through-hole 502 of the second substrate. The source terminal 53 of the second semiconductor switch Q2, the drain terminal 82 of the fifth semiconductor switch Q5, the metal component 600 within the through-hole 502 of the second substrate, and the V-phase terminal 55 are electrically connected to each other. The drain terminal 52 of the second semiconductor switch Q2 is electrically connected to the power line Lp via printed wiring (not shown) and vias (not shown) on the first circuit surface 11A. The source terminal 83 of the fifth semiconductor switch Q5 is electrically connected to the ground line Ln via printed wiring (not shown) and / or vias (not shown) on the second circuit surface 11B.

[0138] The W-phase terminal 65 is disposed on the first circuit surface 11A behind the through-hole 503 of the third substrate. The source terminal 63 of the third semiconductor switch Q3, the drain terminal 92 of the sixth semiconductor switch Q6, the metal component 600 within the through-hole 503 of the third substrate, and the W-phase terminal 65 are electrically connected to each other. The drain terminal 62 of the third semiconductor switch Q3 is electrically connected to the power line Lp via printed wiring (not shown) and through-holes on the first circuit surface 11A. The source terminal 93 of the sixth semiconductor switch Q6 is electrically connected to the ground line Ln via printed wiring (not shown) and / or through-holes (not shown) on the second circuit surface 11B.

[0139] The elastic member 35 is conductive. Specifically, the elastic member 35 is a leaf spring made of metal such as copper or aluminum. More specifically, the elastic member 35 has a cross-section that is Z-shaped but not limited to a Z-shape. In other embodiments, the elastic member 35 may also be a metal helical spring. Alternatively, the elastic member 35 may also be a sponge with its surface covered by a conductive material.

[0140] Two elastic members 35 are disposed on the first circuit surface 11A to the right of the first semiconductor switch Q1 and to the left of the third semiconductor switch Q3. The remaining two elastic members 35 are disposed on the second circuit surface 11B to the right of the fourth semiconductor switch Q4 and to the left of the sixth semiconductor switch Q6. Each elastic member 35 has a first member surface 35A and a second member surface 35B located opposite to the first member surface 35A. The first member surface 35A is bonded to either the first circuit surface 11A or the second circuit surface 11B using solder or the like.

[0141] The metal plates 100 are rectangular plate-shaped components. These metal plates 100 are arranged above the first circuit surface 11A with their long sides aligned horizontally. One metal plate 100 is configured to cover the upper surfaces of three high-side switches (i.e., the first to third semiconductor switches Q1 to Q3). The upper surfaces of the three high-side switches include metal surfaces 46, 56, and 66 (first to third sides). The other metal plate 100 is configured to cover the upper surfaces of three low-side switches (i.e., the fourth to sixth semiconductor switches Q4 to Q6). The upper surfaces of the three low-side switches include metal surfaces 76, 86, and 96 (fourth to sixth sides). The four elastic members 35 are not covered by these metal plates 100. These metal plates 100 are components that improve the heat dissipation efficiency of the heat generated by the first to sixth semiconductor switches Q1 to Q6. Furthermore, Figure 7 The cross-section along the high-side switch is shown. The structure around the low-side switch is essentially the same as that around the high-side switch. Therefore, the structure around the high-side switch will be described below, while the description of the structure around the low-side switch will be omitted.

[0142] The metal plate 100 includes: (i) a first plate surface 100A, and (ii) a second plate surface 100B located opposite to the first plate surface 100A. The first plate surface 100A is bonded to the first to third metal surfaces 46, 56, and 66 by means of solder. In other embodiments, the first plate surface 100A may also be bonded to the first to third metal surfaces 46, 56, and 66 by means of an adhesive with relatively high thermal conductivity. Examples of adhesives with relatively high thermal conductivity include: silicone and epoxy resin.

[0143] The metal plate 100 includes: a metal base 140, an insulating layer 130, first to third metal foils 111 to 113, a right insulating portion 121, first and second insulating portions 122 and 123, and a left insulating portion 124. The metal base 140 is an aluminum metal plate. That is, the metal base 140 is a metal plate with high thermal conductivity and excellent heat dissipation. In other embodiments, the metal base 140 can be a metal plate formed of other metals such as copper. The metal base 140 can also be any metal plate with excellent heat dissipation. The upper surface of the metal base 140 corresponds to the second plate surface 100B.

[0144] The insulating layer 130 is bonded to the lower surface of the metal base 140. More specifically, the upper surface of the insulating layer 130 is bonded to the lower surface of the metal base 140 using an adhesive or the like. The insulating layer 130 comprises, or is formed of, a material with excellent insulation and heat dissipation properties. Examples of such materials include, for example, silicon and epoxy resin.

[0145] The first to third metal foils 111 to 113, the right insulating portion 121, the first and second insulating portions 122 and 123, and the left insulating portion 124 are bonded to the lower surface of the insulating layer 130. The first to third metal foils 111 to 113, the right insulating portion 121, the first and second insulating portions 122 and 123, and the left insulating portion 124 form the first plate surface 100A. In other words, the first to third metal foils 111 to 113, the right insulating portion 121, the first and second insulating portions 122 and 123, and the left insulating portion 124 are included in the first plate surface 100A.

[0146] The first to third metal foils 111 to 113 are square metal foils (sheets), specifically copper foils. The first to third metal foils 111 to 113 each have a size equivalent to that of the first to third metal surfaces 46, 56, and 66. In other embodiments, the first to third metal foils 111 to 113 may also be other metal foils such as silver or gold foil.

[0147] The first metal foil 111 is disposed on the first plate surface 100A opposite to the first metal surface 46. The second metal foil 112 is disposed on the first plate surface 100A opposite to the second metal surface 56. The third metal foil 113 is disposed on the first plate surface 100A opposite to the third metal surface 66. That is, the first to third metal foils 111 to 113 are arranged in the left-right direction with the same spacing as the first to third semiconductor switches Q1 to Q3.

[0148] The first metal foil 111 is bonded to the first metal surface 46 using solder 101. The second metal foil 112 is bonded to the second metal surface 56 using solder 102. The third metal foil 113 is bonded to the third metal surface 66 using solder 103. However, current does not flow between the first to third metal foils 111 to 113 and the first to third metal surfaces 46, 56, and 66. The first to third metal foils 111 to 113 are disposed on the first board surface 100A for brazing the metal plate 100 to the first to third semiconductor switches Q1 to Q3. Depending on the type of metal contained in the metal plate 100, it is difficult to braze the first to third metal surfaces 46, 56, and 66 to the metal plate 100. In particular, when the metal contained in the metal plate 100 is aluminum, it is difficult to achieve brazing. The first plate 100A includes the first to third metal foils 111 to 113, and the first to third metal surfaces 46, 56, and 66 can be brazed to the first plate 100A.

[0149] Solders 101 to 103 are alloys containing lead and / or tin, and have higher thermal conductivity than resins. The first to third semiconductor switches Q1 to Q3 are bonded to the metal plate 100 using solders 101 to 103, which have high thermal conductivity. Therefore, compared to bonding the first to third semiconductor switches Q1 to Q3 to the metal plate 100 using resins or the like, the heat dissipation efficiency of the heat dissipation path from the first to third semiconductor switches Q1 to Q3 toward the metal plate 100 is improved.

[0150] In other embodiments, the first to third semiconductor switches Q1 to Q3 may also be bonded to the metal plate 100 by means of a thermally conductive material (TIM), and the first to third metal foils 111 to 113 are removed from the metal plate 100. Examples of TIM include thermal paste, thermal adhesive, thermal sheet, thermally conductive compound, and thermal gel.

[0151] The first and second insulating portions 122 and 123, the right insulating portion 121, and the left insulating portion 124 are solder resist (or solder mask) applied to the insulating layer 130. In other embodiments, the first and second insulating portions 122 and 123, the right insulating portion 121, and the left insulating portion 124 may be formed of an insulating material or may contain an insulating material. Examples of insulating materials include silicon and epoxy resin.

[0152] The first insulating portion 122 is disposed between the first metal foil 111 and the second metal foil 112. The second insulating portion 123 is disposed between the second metal foil 112 and the third metal foil 113. The right insulating portion 121 is disposed to the right of the first metal foil 111. The left insulating portion 124 is disposed to the left of the third metal foil 113.

[0153] A through-hole 160 is formed in the metal plate 100, through which the first insulating portion 122, the insulating layer 130 above it, and the metal base 140 pass. The through-hole 160 is opposite to a first thermistor 27 mounted on the first circuit surface 11A. Since the second height H2 is greater than the first height H1, the first thermistor 27 is not housed between the first circuit surface 11A and the first insulating portion 122. Thus, the through-hole 160 is formed in the metal plate 100. A portion of the first thermistor 27 is housed within the through-hole 160.

[0154] Two internal threads 150 are formed on the metal plate 100. Each internal thread 150 includes a helical thread. One internal thread 150 is formed on the inner surface of a through hole through which the right insulating portion 121, the insulating layer 130 above it, and the metal base 140 pass. The other internal thread 150 is formed on the inner surface of a through hole through which the left insulating portion 124, the insulating layer 130 above it, and the metal base 140 pass. In this embodiment, the internal threads 150 are formed on the inner surface of each through hole in the metal base 140. In other embodiments, either internal thread 150 may also be formed on the inner surface of the corresponding through hole in the metal base 140.

[0155] The second plate surface 100B is bonded to the bonding layer 300. The heat dissipation component 200 is in indirect contact with the second plate surface 100B via the bonding layer 300. The bonding layer 300 is formed by applying a material having (i) adhesion and (ii) a thermal conductivity higher than air onto the second plate surface 100B, or by attaching a sheet of such material to the second plate surface 100B. Specifically, the bonding layer 300 is formed of TIM, and more specifically, of a thermally conductive compound. Generally, the second plate surface 100B has minor irregularities. In addition, the bottom surface of the heat dissipation component 200 also has minor irregularities. The bonding layer 300 improves the heat dissipation efficiency of the heat dissipation path from the metal plate 100 to the heat dissipation component 200 by filling the gap between the second plate surface 100B and the bottom surface of the heat dissipation component 200. In other embodiments, the bonding layer 300 and the heat dissipation component 200 can be removed from the drive unit 25. If sufficient heat dissipation can be achieved with only the metal plate 100, the heat dissipation component 200 may not need to be connected to the metal plate 100.

[0156] In other embodiments, the sealing layer 300 can be removed from the drive unit 25, and the heat dissipation component 200 can be directly bonded to the second plate surface 100B. Alternatively, in other embodiments, the metal plate 100 and the sealing layer 300 can be removed from the drive unit 25. An insulating layer can also be formed on the bottom surface of the heat dissipation component 200, and three metal foils can be disposed on the insulating layer. Furthermore, the three metal foils can be brazed to the first to third metal surfaces 46, 56, and 66 of the first to third semiconductor switches Q1 to Q3.

[0157] The right and left ends of the heat sink 200 contact the second component surface 35B of one of the two elastic components 35. The heat sink 200 is not fixed to these second component surfaces 35B, but is supported by the elastic force of these elastic components 35. Therefore, the assembly tolerances of the first to third semiconductor switches Q1 to Q3, the metal plate 100, the sealing layer 300, and the heat sink 200 are absorbed by these elastic components 35.

[0158] Since the elastic members 35 are conductive, the circuit board 11 is electrically connected to the heat dissipation member 200. This suppresses the occurrence of static electricity on the circuit board 11. Consequently, local voltage rises on the circuit board 11 caused by static electricity are suppressed. Furthermore, damage to electronic components on the circuit board 11 due to electrostatic discharge is suppressed.

[0159] In other embodiments, heat dissipation components 200 and 500 can be supported by either a single elastic member or by three or more elastic members. Alternatively, the drive unit 25 can replace the two heat dissipation components 200 and 500, and instead include a single heat dissipation component covering the upper surfaces of the first to sixth semiconductor switches Q1 to Q6. This single heat dissipation component can be supported by either a single elastic member or by three or more elastic members. The single elastic member or the three or more elastic members can each be configured similarly to the elastic member 35.

[0160] The heat dissipation component 200 is a heat sink made of metals such as aluminum or copper. For example... Figure 7 as well as Figure 8 As shown, the heat dissipation component 200 includes: a base 210, a plurality of heat sinks 220, and a mounting portion 230. The base 210 is plate-shaped and is joined to the bonding layer 300 in a manner that is arranged substantially parallel to the circuit board 11 and the metal plate 100. Two through holes 250 are formed in the base 210. These through holes 250 are formed to be opposite (or arranged) to internal threads 150. The inner surface of each through hole 250 does not have threads, but has a smooth inner surface.

[0161] The plurality of heat sinks 220 are plate-shaped. The plurality of heat sinks 220 are connected to the base 210 with their long sides aligned along the front-back direction. The plurality of heat sinks 220 are arranged in the left-right direction. In other embodiments, the plurality of heat sinks 220 may also be arranged on the base 210 with their long sides facing left-right in the front-back direction. Furthermore, in other embodiments, the plurality of heat sinks 220 may each have other shapes such as a wave-shaped shape or a pointed shape.

[0162] The mounting portion 230 is plate-shaped and has a thickness greater than that of any of the heat sinks 220. The mounting portions 230 are connected to the right end of the base 210 along their long sides in the front-to-back direction. In other embodiments, the mounting portions 230 may also be connected to the left end of the base 210. Alternatively, in other embodiments, the mounting portions 230 may also be connected to the front or rear end of the base 210 along their long sides in the left-to-right direction.

[0163] The heat dissipation component 200 has a first contact surface 200a on the lower side of the base 210. The first contact surface 200a indirectly contacts the first to third semiconductor switches Q1 to Q3 via a metal plate 100 or the like.

[0164] The heat dissipation component 200 has a second contact surface 200b on the right end face of the mounting portion 230, which is different from the first contact surface 200a. The second contact surface 200b extends in a direction intersecting the first contact surface 200a. In this embodiment, the second contact surface 200b extends perpendicularly to the first contact surface 200a.

[0165] Refer again Figure 3 as well as Figure 7 The second contact surface 200b contacts the load switch Q7. The load switch Q7 is a plug-in type switch; that is, the load switch Q7 has a through-hole package. More specifically, the load switch Q7 is a radial lead type switch. Generally, semiconductor switches with through-hole packages have a rated voltage and rated current that are greater than those of semiconductor switches with surface mount packages. In this embodiment, to ensure higher reliability and / or higher durability, the load switch Q7 has a rated voltage and rated current that are greater than those of any one of the first to sixth semiconductor switches Q1 to Q6.

[0166] The load switch Q7 includes a main body 30. The main body 30 is cuboid in shape. The load switch Q7 is screwed to the mounting portion 230 with one outer surface of the main body 30 in contact with the second contact surface 200b of the mounting portion 230. In other embodiments, the load switch Q7 may also be fixed to the mounting portion 230 using a clip or the like with one outer surface of the main body 30 in contact with the second contact surface 200b. Alternatively, in other embodiments, one outer surface of the main body 30 may be bonded to the second contact surface 200b by means of a clamping member 700 such as a thin adhesive sheet.

[0167] The heat generated by the first to third semiconductor switches Q1 to Q3 is transferred to the heat sink 200 via the metal plate 100 and is dissipated through the heat sink 200. The heat generated by the load switch Q7 is directly transferred to the heat sink 200 and is dissipated through the heat sink 200.

[0168] The load switch Q7 includes a first lead 31, a second lead 32, and a third lead 33. The first lead 31 is connected to the gate terminal of the load switch Q7. The second lead 32 is connected to the drain terminal of the load switch Q7. The third lead 33 is connected to the source terminal of the load switch Q7. Through-holes 131, 132, and 133 are formed on the circuit board 11. The through-holes 131, 132, and 133 penetrate the circuit board 11 along its thickness. The first to third leads 31 to 33 protrude downward from the main body 30 and extend downward. The first to third leads 31 to 33 (i) are inserted into the through-holes 131, 132, and 133, and (ii) are electrically connected to printed wiring (not shown) on the first circuit surface 11A via the through-holes 131, 132, and 133.

[0169] Each external threaded component 400 has a threaded portion 410. The threaded portion 410 is a helical thread formed on the side of the cylinder of the corresponding external threaded component 400. The threaded portion 410 is formed at a position corresponding to the internal thread 150 on the external threaded component 400 that is inserted into the through hole 250. The external threaded components 400 are inserted into the corresponding through holes 250, and the corresponding threaded portions 410 engage with the corresponding internal threads 150. Through the engagement of these threaded portions 410 and these internal threads 150, the heat dissipation component 200 is securely fixed to the metal plate 100. Furthermore, the tightness of the contact between the heat dissipation component 200, the sealing layer 300, and the metal plate 100 is improved, thereby increasing the heat dissipation efficiency from the metal plate 100 towards the heat dissipation component 200.

[0170] In other embodiments, instead of the internal thread 150 formed on the metal plate 100, the drive unit 25 may also include two nuts (internal threads) (i.e., the drive unit 25 may also include a total of four nuts). Two external threaded parts 400 may also engage with the two nuts on the underside of the right insulating portion 121 and the left insulating portion 124.

[0171] Metal plate 100 and heat sink 500, which replaces heat sink 200, are attached to the low-side switch. The basic structure of heat sink 500 is the same as that of heat sink 200. Hereinafter, the differences between heat sink 500 and heat sink 200 will be explained.

[0172] The heat dissipation component 500 includes a base 510, a plurality of heat sinks 520, and an outer peripheral wall 540. The base 510 is a plate-shaped component with a length greater than that of the base 210 in the left-right direction. Each of the plurality of heat sinks 520 has the same shape as the plurality of heat sinks 220. The heat dissipation component 500 does not include a mounting portion 230. The plurality of heat sinks 520 are connected to the base 510 with their long sides facing the front-back direction. The plurality of heat sinks 520 are arranged in the left-right direction. In other embodiments, the plurality of heat sinks 520 may also be arranged in the front-back direction on the base 510 with their long sides facing the left-right direction. Furthermore, in other embodiments, the plurality of heat sinks 520 may have other shapes such as a wavy shape or a pointed shape.

[0173] The outer peripheral wall 540 is connected to the upper surface of the base 510. The outer peripheral wall 540 has a height that is the same as the length from the upper surface of the base 510 to the upper end of the heat dissipation component 200. The outer peripheral wall 540 surrounds the left, right, front, and rear sides of the circuit board 11, the two metal plates 100, and the heat dissipation component 200, respectively.

[0174] After assembling the first to sixth semiconductor switches Q1 to Q6, two metal plates 100, heat sink 200, and heat sink 500 onto the circuit board 11, resin is injected into the inner side of the outer peripheral wall 540, and the drive unit 25 is molded from the resin. The resin-molded drive unit 25 is housed in the housing 2.

[0175] In other embodiments, the outer peripheral wall 540 may be removed from the heat dissipation component 500. When the outer peripheral wall 540 is removed, the drive unit 25 is held in a mold and molded with resin. The resin-molded drive unit 25 is housed in the housing 2. Alternatively, when the outer peripheral wall 540 is removed, the drive unit 25 may also be housed in a housing. The drive unit 25 housed in the housing is in turn housed in the housing 2.

[0176] <1-3-2. Variation>

[0177] Reference Figure 8 This section describes a modified example of the drive unit 25. The modified example differs from the embodiment described above in that, instead of the second height H2, the first thermistor 27 has a third height H3. Furthermore, the modified example differs from the embodiment described above in that, through-holes 160 are not formed in the metal plate 100. The third height H3 is smaller than the first height H1. Therefore, the first and second thermistors 27 and 29 involved in the modified example are housed between the first and second circuit surfaces 11A and 11B and the first insulating portion 122; thus, through-holes 160 are not formed in the metal plate 100 involved in the modified example.

[0178] <1-3-3. Effect>

[0179] According to the embodiment described in detail above, the following effects can be achieved.

[0180] (1) The source terminal 43 of the first semiconductor switch Q1 is electrically connected to the drain terminal 72 of the fourth semiconductor switch Q4 via a metal component 600 inserted into the through-hole 501 of the first substrate. Since the width of the metal component 600 is greater than the diameter of the through-hole, the width of the first and fourth printed wirings 511 and 521 can be increased. Furthermore, the inductance of the first and fourth printed wirings 511 and 521 can be reduced. In addition, since the metal component 600 is solid, the inductance of the metal component 600 can be made smaller than the inductance of the through-hole. Therefore, the inductance of the current path on the circuit board 11 can be reduced, thereby suppressing the surge voltage generated with the switching operation of the first and fourth semiconductor switches Q1 and Q4.

[0181] (2) The source terminals 43, 53, and 63 of the first to third semiconductor switches Q1 to Q3 are respectively positioned opposite the drain terminals 72, 82, and 92 of the fourth to sixth semiconductor switches Q4 to Q6 across the circuit board 11. This minimizes the printed wiring between the source terminals 43, 53, and 63 and the drain terminals 72, 82, and 92. Furthermore, it further reduces the inductance of the circuit board 11, thereby further suppressing surge voltages generated during the switching operations of the first to sixth semiconductor switches Q1 to Q6.

[0182] (3) The length of the first portion 610 of the metal component 600 in the long side direction is greater than the length in the left-right direction of the through holes 501-503 of the first to third substrates. The length of the second portion 620 in the long side direction is less than the length in the left-right direction of the through holes 501-503 of the first to third substrates. Therefore, the second portion 620 is accommodated in the through holes 501-503 of the first to third substrates, and a portion of the lower surface of the first portion 610 abuts against the first circuit surface 11A. Accordingly, it is possible to prevent the metal component 600 from falling off the circuit board 11.

[0183] (4) The first to third substrate through holes 501 to 503 extend along the second ends 46B to 66B of the first to third semiconductor switches Q1 to Q3, respectively. Therefore, the first to third substrate through holes 501 to 503 can be disposed near the first to third semiconductor switches Q1 to Q3, respectively. Furthermore, the printed wiring between the source terminals 43, 53, and 63 of the first to third semiconductor switches Q1 to Q3 and the drain terminals 72, 82, and 92 of the fourth to sixth semiconductor switches Q4 to Q6 can be further shortened, thereby further suppressing the surge voltage generated during the switching operation of the first to sixth semiconductor switches Q1 to Q6.

[0184] (5) Solder resist 15 is applied between the second ends 46B, 56B, and 66B of the first to third semiconductor switches Q1 to Q3 and the through holes 501 to 503 of the first to third substrates. Accordingly, it is possible to avoid contact between the solder that bonds the metal parts 600 and the printed wirings 511 to 513 and the solder that bonds the source terminals 43, 53, and 63 and the printed wirings 511 to 513.

[0185] <1-3-4. Correspondence of Terms>

[0186] In this embodiment, the metal component 600 corresponds to an example of a solid metal component in the summary of the embodiment, and the first to third substrate through holes 501 to 503 correspond to an example of through holes in the summary of the embodiment.

[0187] (2. Other implementation methods)

[0188] (a) In the above embodiments, although one metal plate 100 is coupled to three high-side switches and one metal plate 100 is coupled to three low-side switches, the present invention is not limited thereto. Figure 3 , 6In addition, as shown by the dotted line in section 7, one metal plate 100 can also be attached to one semiconductor switch. This increases the flexibility in the arrangement of the semiconductor switches by attaching different metal plates 100 to each semiconductor switch. That is, it is not necessary to arrange the three high-side switches or the three low-side switches in a row. Six semiconductor switches can be freely arranged on the first circuit surface 11A and the second circuit surface 11B. Furthermore, one metal plate 100 can also be attached to two semiconductor switches. Moreover, one heat sink 200 or another heat sink can be securely connected to one metal plate 100 using the external threaded component 400. Alternatively, one heat sink 200 or another heat sink can be securely connected to multiple metal plates 100 using the external threaded component 400.

[0189] (b) In the above embodiment, although the first semiconductor switch Q1 to the sixth semiconductor switch Q6 are indirectly in contact with the heat sink 200 or the heat sink 500 by means of the metal plate 100 and the bonding layer 300, in another embodiment, the first semiconductor switch Q1 to the sixth semiconductor switch Q6 may also be in direct contact with the heat sink 200 or the heat sink 500 (see reference). Figure 9 Alternatively, six heat dissipation components can be provided corresponding to the first to sixth semiconductor switches Q1 to Q6 respectively. The first to sixth semiconductor switches Q1 to Q6 can also directly contact the six heat dissipation components respectively, or indirectly contact them through an intermediary component.

[0190] (c) In the above embodiment, the first to sixth semiconductor switches Q1 to Q6 have metal surfaces 46 to 96 on the side opposite to the circuit board 11, but the present invention is not limited to this configuration. In another embodiment, the first to sixth semiconductor switches Q1 to Q6 (i) may have additional metal surfaces corresponding to the circuit board 11 in addition to the metal surfaces 46 to 96, or alternatively, may be configured to dissipate heat from the additional metal surfaces. More specifically, the first to sixth semiconductor switches Q1 to Q6 may also have DSOP or TO-Leadless (TOLL) packages respectively.

Claims

1. An electric work machine, characterized in that, The electric work machine has the following features: A motor is configured to receive power from a power source for driving. A circuit board having a first circuit surface, a second circuit surface on the opposite side of the first circuit surface, and a through hole; A first semiconductor switch, which is electrically connected to the power supply and the motor, and is located on the first circuit surface, has a first terminal; The second semiconductor switch, which is electrically connected to the power supply and the motor and is located on the second circuit surface, is different from the first semiconductor switch and has a second terminal; A first conductive line is disposed on the first circuit surface and electrically connected to the first terminal; A second conductive line is disposed on the second circuit surface and electrically connected to the second terminal; as well as A solid metal component is inserted into the through hole and electrically connected to the first conductive line and the second conductive line.

2. The electric work machine according to claim 1, characterized in that, The first semiconductor switch corresponds to the high-side switch of the drive circuit that drives the motor. The second semiconductor switch corresponds to the low-side switch of the driving circuit. The first terminal is positioned opposite the second terminal across the circuit board.

3. The electric work machine according to claim 1 or 2, characterized in that, The first semiconductor switch and the second semiconductor switch are field-effect transistors. The first terminal is the source terminal of the first semiconductor switch. The second terminal is the drain terminal of the second semiconductor switch.

4. The electric work machine according to any one of claims 1 to 3, characterized in that, The solid metal component includes: a first portion protruding from the through hole, and a second portion received within the through hole. The through hole has a first length in a predetermined direction along the first circuit surface. The first part has a second length that is greater than the first length in the specified direction. The second part has a third length that is smaller than the first length in the specified direction.

5. The electric work machine according to any one of claims 1 to 4, characterized in that, The through hole extends along the end of the first semiconductor switch.

6. The electric work machine according to claim 5, characterized in that, The through hole has a cuboid shape.

7. The electric work machine according to claim 6, characterized in that, The first semiconductor switch and the second semiconductor switch have a cuboid shape. The short side direction of the first semiconductor switch is consistent with the short side direction of the second semiconductor switch. The long side of the through hole is aligned with the short side of the first semiconductor switch and the second semiconductor switch.

8. The electric work machine according to claim 5, characterized in that, The first conductive line includes: a solder resist applied between the end and the through hole.

9. A method for assembling a drive unit for driving a motor of an electric work machine, characterized in that, The method comprises the following steps: The first semiconductor switch of the driving unit is mounted on the first circuit surface of the circuit board of the driving unit, and the first circuit surface has a first conductive line. A second semiconductor switch, different from the first semiconductor switch, is mounted on a second circuit surface on the circuit substrate opposite to the first circuit surface, and the second circuit surface has a second conductive line. A solid metal component is inserted into a through hole in the circuit board. The first terminal of the first semiconductor switch is electrically connected to the first conductive line; The second terminal of the second semiconductor switch is electrically connected to the second conductive line; as well as The first conductive line and the second conductive line are electrically connected to the solid metal component.

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