WO2024201738A1

WO2024201738A1 - Electric motor and air conditioner

Info

Publication number: WO2024201738A1
Application number: PCT/JP2023/012616
Authority: WO
Inventors: 隼一郎尾屋
Original assignee: 三菱電機株式会社
Priority date: 2023-03-28
Filing date: 2023-03-28
Publication date: 2024-10-03

Abstract

This electric motor comprises: a rotor; a stator provided on the outer circumference of the rotor; a control board which controls the driving of the rotor and on which surface mounting elements are mounted; and a mold resin that is integrally molded with the control board. The control board has an adhesion layer (2) disposed between the control board and the mold resin so as to surround the surface mounting elements. The area of the adhesion layer (2) is not less than the total area of an electrode layer that is disposed in an element mounting region, which is a region where the surface mounting elements are mounted, and that is connected to electrodes of the surface mounting elements via solder.

Description

Electric motors and air conditioners

This disclosure relates to an electric motor and an air conditioner that have a molded resin integrally molded with a control board.

In recent years, there has been a demand for higher output fan motors in air conditioners to save energy and improve the heating capacity of the units. To achieve higher output, power integrated circuits (ICs) used in high-power circuits are used, but the heat dissipation of these power ICs has become an issue. To improve heat dissipation, a technology is known in which a substrate containing a power IC is integrally molded from resin.

Patent Document 1 discloses a molded motor that includes a motor frame with a built-in stator, a rotor that is provided inside the motor frame, and a bearing that supports the rotor so that it can rotate freely. The motor frame has a structure in which the stator and a donut-shaped control board that is provided on the opposite output side of the stator and has a Hall IC surface-mounted on the pad, which is an electrode layer, are housed inside a mold and integrally molded with molded resin. In Patent Document 1, silk with a first pattern, a second pattern, and a third pattern is arranged around the arrangement position of the Hall IC. The first pattern is arranged to surround the entire Hall IC so that the rough position of the Hall IC can be determined and when the pin, which is an electrode, is soldered to the pad, the solder flows out to parts other than the first pattern and prevents a short circuit with other components. The second pattern is arranged to position the Hall IC on the control board and is arranged to surround the periphery of the body except for the pin connected to the pad. The third pattern is arranged in the area between the pads.

JP 2006-080243 A

Meanwhile, not only Hall ICs but also other surface mount elements such as power ICs are mounted on the control board of the motor frame. Usually, the surface area of the body of the Hall IC facing the control board is about 1 ^mm2 , whereas the surface area of the body of the power IC facing the control board is 12 ^mm2 or more. In general, the degree of adhesion between the molded resin and the control board is not so high. For this reason, in a surface mount element larger in size than the Hall IC, a gap is generated between the control board around the surface mount element and the molded resin due to repeated thermal expansion and contraction caused by heat shock. When a gap is generated, the surface mount element is no longer fixed between the control board and the molded resin, and the repeated thermal expansion and contraction cause solder cracks in the solder connecting the pads and pins, which reduces the heat shock resistance and may result in the heat shock test not satisfying the standard.

The present disclosure has been made in consideration of the above, and aims to obtain an electric motor that can reduce the occurrence of cracks due to heat shock in the solder that connects the electrode layer of the control board molded with molded resin and the electrodes of the surface-mounted elements, more than ever before.

In order to solve the above-mentioned problems and achieve the object, the electric motor according to the present disclosure comprises a rotor, a stator provided on the outer periphery of the rotor, a control board that controls the drive of the rotor and on which surface-mounted elements are mounted, and a molded resin integrally molded with the control board. The control board has an adhesion layer that is disposed between the control board and the molded resin so as to surround the surface-mounted elements. The area of the adhesion layer is equal to or greater than the total area of the electrode layers that are disposed in the element mounting area, which is the area in which the surface-mounted elements are mounted, and are connected to the electrodes of the surface-mounted elements via solder.

The electric motor disclosed herein has the advantage of being able to suppress the occurrence of cracks due to heat shock in the solder connecting the electrode layer of the control board molded with molded resin and the electrodes of the surface-mounted elements, more than ever before.

FIG. 1 is a diagram showing an example of a configuration of an electric motor according to a first embodiment; FIG. 1 is a diagram showing an example of a circuit configuration of a built-in board included in an electric motor according to a first embodiment; FIG. 1 is a top view showing a schematic example of a configuration of a built-in substrate that constitutes an electric motor according to a first embodiment; FIG. 1 is a diagram showing an example of a mounting state of a surface-mounted IC on a built-in substrate constituting an electric motor according to a first embodiment; FIG. 1 is a cross-sectional view showing a schematic example of a structure of a chip resistor; FIG. 13 is a cross-sectional view showing an example of a state of a chip resistor when a gap occurs between the built-in substrate and the mold resin; FIG. 13 is a top view showing another example of a state in which elements are mounted on a built-in substrate constituting the electric motor according to the first embodiment; FIG. 13 is a top view showing another example of a state in which elements are not mounted on the built-in substrate constituting the electric motor according to the first embodiment; FIG. 11 is a cross-sectional view showing a schematic example of a configuration of an electric motor according to a second embodiment; FIG. 11 is a schematic diagram illustrating an example of the configuration of an air conditioner according to a third embodiment.

Below, the electric motor and air conditioner according to the embodiment of the present disclosure are described in detail with reference to the drawings.

Embodiment 1.
Fig. 1 is a diagram showing an example of the configuration of an electric motor according to embodiment 1. In embodiment 1, a case will be described in which electric motor 1 is a three-phase electric motor, but electric motor 1 in embodiment 1 is not limited to a three-phase electric motor.

The electric motor 1 is a brushless DC (Direct Current) motor. In FIG. 1, a portion of the electric motor 1 is shown in cross section to explain the configuration of the electric motor 1. The electric motor 1 comprises a rotor 30, a stator 20, a built-in board 11 that is a control board, and molded resin 12. A rotating shaft 31 is inserted into the rotor 30. The stator 20 is provided on the outer periphery of the rotor 30. The built-in board 11 has a board circuit that is a circuit that controls the drive of the rotor 30.

The stator 20, the built-in substrate 11, and the molded resin 12 are fixed by the molded stator 10. The molded stator 10 is formed by integrally molding the stator 20 and the built-in substrate 11. That is, the stator 20 and the built-in substrate 11 are fixed by the molded stator 10 so as to be integrated. The molded stator 10 also has a recess formed therein that is capable of accommodating the rotor 30. The stator 20 and the built-in substrate 11 may be integrally molded separately. In this case, the integrally molded stator 20 and the integrally molded built-in substrate 11 are joined. This improves the heat dissipation of the power IC and the like, and makes it possible to suppress temperature rise.

The stator 20 has multiple stator cores 21, insulators 23 molded integrally with the stator cores 21, and a winding group 22. The stator cores 21 are formed by laminating electromagnetic steel sheets. The insulators 23 insulate the stator cores 21 from the winding group 22.

In the electric motor 1, the stator 20 is formed by winding the windings of the winding group 22 around each slot of the stator core 21, which is integrally molded with the insulator 23. Each winding of the winding group 22 is made of copper, aluminum, or the like.

The electric motor 1 has an output side bearing 33 at one end of the rotating shaft 31 that rotatably supports the rotating shaft 31, a non-output side bearing 34 at the other end of the rotating shaft 31 that rotatably supports the rotating shaft 31, and a conductive bracket 60 that covers the non-output side bearing 34.

The bracket 60 is fitted into the inner circumference of the molded stator 10 with the press-in portion 61 of the bracket 60 so as to cover the opening of the recess provided in the molded stator 10. In addition, the outer ring of the non-output side bearing 34 is fitted inside the bracket 60.

The built-in board 11 has a circuit including a power IC 80, a control unit, and a magnetic sensor 50 such as a Hall IC that detects the position of the rotor 30.

The built-in board 11 is disposed perpendicular to the axial direction of the rotating shaft 31 between the output bearing 33 and the stator 20, and is fixed to the insulator 23. The power IC of the built-in board 11 and the windings of the winding group 22 are connected via winding terminals. The built-in board 11 has a lead outlet 14 from which lead wires 13 are drawn out to connect to a higher-level system such as a board on the unit side of an air conditioner. The higher-level system is a system in which the electric motor 1 is mounted. In one example, the lead wires 13 are connected to a board on the unit side of an air conditioner such as the indoor unit board 211. The built-in board 11 also has components such as operational amplifiers, comparators, regulators, diodes, resistors, capacitors, inductors, and fuses.

In one example, the shape of the built-in substrate 11 is a disk with a through hole formed in the center. The shape of the built-in substrate 11 may be a shape other than a disk, such as a semicircular shape. The rotating shaft 31 passes through the through hole provided in the built-in substrate 11. The built-in substrate 11 is disposed inside the electric motor 1 so that the top and bottom surfaces are perpendicular to the axial direction of the rotating shaft 31.

The rotor 30 has a rotor insulation part 32, which is an annular member, arranged on the outer periphery of the rotating shaft 31. The rotor 30 has a magnet 40 arranged inside the molded stator 10. The magnet 40 is arranged on the outer periphery of the rotating shaft 31, facing the stator core 21. The magnet 40 is composed of a cylindrical permanent magnet. The magnet 40 is fixed to the rotating shaft 31.

Magnet 40 is produced by injection molding a bonded magnet consisting of a ferrite magnet or a rare earth magnet mixed with a thermoplastic resin material. Examples of rare earth magnets are samarium iron nitrogen magnets and neodymium magnets. A magnet is incorporated into the mold used for injection molding magnet 40, and magnet 40 is molded while applying orientation. Magnet 40 may also be a sintered magnet.

The magnet 40 has, in the axial direction of the rotating shaft 31, a sensor magnet portion which is the portion close to the magnetic sensor 50, and a main magnet portion which is the portion other than the sensor magnet portion. The sensor magnet portion allows the magnetic sensor 50 to detect the position of the rotor 30. The main magnet portion generates a rotational force in the rotor 30 according to the magnetic flux generated by the winding group 22.

The outer diameter of the magnet 40 on the magnetic sensor 50 side of the built-in board 11 is smaller than the outer diameter of the other parts. That is, the outer diameter of the sensor magnet part of the magnet 40 is smaller than the outer shape of the main magnet part. This shape of the magnet 40 makes it easier for magnetic flux to flow into the magnetic sensor 50 mounted on the built-in board 11. The magnetic sensor 50 is positioned far from the winding group 22, that is, close to the rotating shaft 31, to minimize the influence of the magnetic flux generated from the winding group 22 of the stator 20.

Note that while FIG. 1 shows a case in which the main magnet section and the sensor magnet section are configured from a single magnet 40, the main magnet section and the sensor magnet section may be configured from separate magnets.

The magnetic sensor 50 may be configured using a Hall IC whose output signal is a digital signal, or may be configured using a Hall element whose output signal is an analog signal. In other words, the magnetic sensor 50 may be a type that detects the position of the rotor 30 using a Hall IC, or a type that detects the position of the rotor 30 using a Hall element.

The Hall IC may be a first-type Hall IC that detects the position of the rotor 30 using a first method described below, or a second-type Hall IC that detects the position of the rotor 30 using a second method described below.

In the first type Hall IC, the sensor section and amplifier section are composed of separate semiconductor chips. In this first type Hall IC, the sensor section is composed of a semiconductor other than silicon, and the amplifier section is composed of silicon. Hereinafter, the first type Hall IC will be referred to as a non-silicon type Hall IC. In the second type Hall IC, the sensor section and amplifier section are composed of a single silicon semiconductor chip.

In a non-silicon Hall IC, two chips are built in, so the sensor part is positioned so that its center position is different from the center of the IC body. A non-silicon semiconductor such as indium antimonide (InSb) is used for the sensor part of a non-silicon Hall IC. Compared to silicon semiconductors, this non-silicon semiconductor has the advantages of better sensitivity and smaller offset due to stress distortion.

Next, the circuit configuration of the built-in board 11 shown in FIG. 1 will be described. FIG. 2 is a diagram showing an example of the circuit configuration of the built-in board provided in the electric motor according to the first embodiment. FIG. 2 shows the built-in board 11, the winding group 22, and the magnetic sensor 50.

The built-in board 11 includes an overcurrent detection resistor 75, a control unit 70, and a power IC 80.

The control unit 70 is connected to the host system, the gate drive circuit 82, the ground 79A, and the magnetic sensor 50. The control unit 70 is also connected to a low-voltage power supply 78.

The power IC 80 includes a gate drive circuit 82 and a power transistor 81. The power IC 80 is also called an Intelligent Power Module (IPM). The gate drive circuit 82 is connected to a low-voltage power supply 78 and a high-voltage power supply 77. The low-voltage power supply 78 outputs a lower voltage than the high-voltage power supply 77. The high-voltage power supply 77 is a bus power supply. The gate drive circuit 82 is also connected to the power transistor 81 and ground 79B.

The gate drive circuit 82 has a protection circuit 85. The protection circuit 85 is connected to the connection point 41. That is, the protection circuit 85 is connected to ground 79C via the connection point 41 and the overcurrent detection resistor 75.

The power transistor 81 is connected to the winding group 22 of the stator 20 and supplies current to the winding group 22 of the stator 20. The power transistor 81 is also connected to ground 79C via the connection point 41 and the overcurrent detection resistor 75. Grounds 79A-79C are a common ground of the same potential.

The power transistor 81 includes six power transistors 81A-81F. In the power transistor 81, the six power transistors 81A-81F are configured separately. In other words, the six power transistors 81A-81F are each configured as a chip, which is a separate component.

The gate drive circuit 82 may be configured as one IC, or may be configured as three separate ICs for three phases. The gate drive circuit 82 and the control unit 70 may be configured as one IC. The control unit 70 may be configured as one IC. In one example, the control unit 70 may be configured as a control IC, which is a dedicated IC that does not require software, or may be configured as a microcomputer or the like. In the following, the microcomputer is referred to as a microcomputer. Furthermore, the six power transistors 81A-81F, the gate drive circuit 82, the protection circuit 85, and the control unit 70 may be configured as one IC, or the gate drive circuit 82, the protection circuit 85, and the control unit 70 may be configured as one IC.

The power transistors 81A-81F are composed of superjunction MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), planar MOSFETs, IGBTs (Insulated Gate Bipolar Transistors), etc. Since a large current flows through the power transistors 81A-81F, they generate a lot of heat, which can cause problems with heat dissipation.

In the first embodiment, a case will be described in which the magnetic sensor 50 detects the magnetic pole position of the rotor 30 corresponding to the magnetic flux position, and the built-in board 11 controls the electric motor 1 based on the magnetic pole position. The built-in board 11 may perform sensorless control of the electric motor 1 while estimating the magnetic pole position from the current flowing through the winding group 22 and the voltage applied to and generated by the winding group 22. The built-in board 11 may also amplify a current signal obtained by using a shunt resistor and a current sensor for current detection using an operational amplifier or the like. Furthermore, the built-in board 11 may use a comparator to generate a signal to the control unit 70 for overcurrent protection from this current signal.

In the built-in board 11, the voltage that drives the gates of the power transistors 81A-81F, for example 15V, may differ from the microcomputer power supply voltage that drives the control unit 70 such as a microcomputer, for example 5V. In this case, the motor 1 uses a regulator to generate one power supply from another power supply supplied from the outside. In one example, a 15V power supply is supplied to the built-in board 11 from the outside, and the regulator generates a 5V power supply and supplies it to the built-in board 11. This regulator may be built into the gate drive circuit 82, the control unit 70 which is a control IC, or the power IC 80.

The power transistor 81 converts the input DC voltage into a three-phase AC voltage consisting of U-phase, V-phase, and W-phase, and supplies it to the winding group 22 of the stator 20. Power transistor 81A is a U-phase upper arm power transistor, power transistor 81B is a V-phase upper arm power transistor, and power transistor 81C is a W-phase upper arm power transistor. Power transistor 81D is a U-phase lower arm power transistor, power transistor 81E is a V-phase lower arm power transistor, and power transistor 81F is a W-phase lower arm power transistor.

In other words, power transistor 81A is the power transistor of the upper arm of U phase, power transistor 81B is the power transistor of the upper arm of V phase, and power transistor 81C is the power transistor of the upper arm of W phase. Also, power transistor 81D is the power transistor of the lower arm of U phase, power transistor 81E is the power transistor of the lower arm of V phase, and power transistor 81F is the power transistor of the lower arm of W phase.

In this way, the power transistor 81 has multiple power transistors 81A-81C in the upper arm and multiple power transistors 81D-81F in the lower arm. In the first embodiment, the power transistors in the upper arm and lower arm that switch more frequently are distributed and arranged on the top surface of the built-in substrate 11 and the bottom surface opposite the top surface. Also, in the first embodiment, the power transistor in the upper arm and lower arm that switches less frequently is arranged on the top surface of the built-in substrate 11.

The motor 1 has a U-phase winding 22U, a V-phase winding 22V, and a W-phase winding 22W as windings included in the winding group 22. The U-phase winding 22U is connected to

power transistors

81A and 81D. The V-phase winding 22V is connected to

power transistors

81B and 81E. The W-phase winding 22W is connected to

power transistors

81C and 81F.

The gate drive circuit 82 controls the on and off of the power transistors 81A-81F according to the switching signal received from the control unit 70.

Three magnetic sensors 50 are arranged around the winding group 22. Each of the three magnetic sensors 50 outputs a magnetic pole position signal corresponding to the position of the rotor 30 to the control unit 70.

In addition, when at least one of the power transistor 81 and the gate drive circuit 82 becomes too hot, the protection circuit 85 turns off all of the power transistors 81A-81F of the power transistor 81 to prevent element destruction due to high temperatures.

Overcurrent detection resistor 75 is connected to the lower arm switches of power transistors 81D-81F, and is part of protection circuit 85. Protection circuit 85 is a circuit that performs overcurrent protection, overheat protection, and power supply overvoltage and constant voltage protection. Protection circuit 85 monitors the voltage of overcurrent detection resistor 75, and when the voltage of overcurrent detection resistor 75 reaches or exceeds a specific value, it forcibly turns off power transistors 81A-81F to prevent overcurrent from flowing through winding group 22, thereby realizing overcurrent protection. Overcurrent detection resistor 75, which is an overcurrent detection unit, may be built into control unit 70 or gate drive circuit 82.

The built-in board 11 may also be equipped with a temperature sensor (not shown). In this case, when the control unit 70 receives a signal from the temperature sensor indicating an abnormal temperature, it forcibly turns off the power transistors 81A-81F to achieve overheat protection.

The control unit 70 performs pulse width modulation (PWM) control on the power transistors 81A-81F by outputting a switching signal to the gate drive circuit 82. The control unit 70 estimates the magnetic pole position of the rotor 30 based on the magnetic pole position signal input from the magnetic sensor 50, and calculates the rotation speed of the rotor 30 from the estimated magnetic pole position. The control unit 70 outputs a rotation speed signal indicating the calculated rotation speed to a higher-level system.

The electric motor 1, which is a brushless DC motor, obtains rotational power by switching six power transistors 81A-81F (in the case of a three-phase motor) at appropriate timing according to the magnetic pole position of the magnet 40 of the rotor 30. The switching signal used for this switching is generated by the control unit 70. The operating principle of this electric motor 1 will be explained below.

In the electric motor 1, the control unit 70 estimates the magnetic pole position of the rotor 30 based on the magnetic pole position signal from the magnetic sensor 50 or the current value of the current flowing through the winding group 22. The control unit 70 generates switching signals for switching the power transistors 81A-81F according to the magnetic pole position of the rotor 30 and the speed command signal output from the higher-level system. The gate drive circuit 82 switches the power transistors 81A-81F on and off according to the switching signals generated by the control unit 70.

The energization methods used by the motor 1 include 120° energization control, 150° energization control, and sine wave energization control.

Taking 120° energization control as an example, the timing at which the six power transistors 81A-81F are switched on and off is the same as the rising and falling edges of the detection signals from the three Hall ICs. For this reason, in 120° energization control, the control unit 70 can be configured as a combinational circuit that does not require a clock.

On the other hand, in the case of control that requires estimation of the magnetic pole position, such as 150° energization control, sinusoidal energization control, phase control, and sensorless control, the control unit 70 is composed of complex digital circuits including a clock. In one example of estimating the magnetic pole position, the timing between each rising and falling edge of the detection signals from three Hall ICs is precisely estimated.

Sensorless control is control that does not use a magnetic sensor 50. In sensorless control, the magnetic pole position is estimated from the current value detected by a current detection resistor, a current detection transformer, etc., and control is performed. In sensorless control, the signal detected by the current detection resistor, current detection transformer, etc. may be amplified using an operational amplifier, etc., as necessary.

As described above, the control unit 70 adjusts the voltage applied to the winding group 22 by PWM control of the power transistors 81A-81F. In order to reduce losses due to switching of the power transistors 81, the motor 1 may switch only one of the upper and lower arms.

Next, the configuration of the built-in board 11 in the electric motor 1 will be described in detail. The above-mentioned power IC 80, Hall IC, Hall element, operational amplifier, comparator, regulator, diode, and other elements are configured as surface-mounted ICs to reduce the cost of individual components by miniaturizing the components and to reduce the cost of mounting on the board. Surface-mounted ICs are an example of surface-mounted elements.

As described above, in one example, the molded stator 10 is formed by insert molding the stator 20 and the built-in substrate 11 into one body using molded resin 12. The built-in substrate 11, on which elements including surface-mounted ICs are mounted, is in close contact with the molded resin 12.

In this way, in the built-in substrate 11 integrally molded with the molded resin 12, compared to an insert-mount type IC such as an SIP (Single Inline Package) or DIP (Dual Inline Package) in which lead wires inserted into through holes are soldered, the heat shock resistance of the surface-mounted IC is lowered and may not satisfy the standards of the heat shock test. In particular, when a gap occurs between the built-in substrate 11 and the molded resin 12 around the surface-mounted IC due to thermal expansion and thermal contraction caused by the heat shock, the heat shock resistance is lowered. The gap occurs between the built-in substrate 11 and the molded resin 12 because the adhesion between the built-in substrate 11 and the molded resin 12 is weak. Also, the gap occurs between the built-in substrate 11 and the molded resin 12 around a large-sized element or around a chip resistor in many cases. Here, a large-sized element refers to an element whose surface area facing the built-in substrate 11 of the body of the surface-mounted IC is 12 mm ² or more. Moreover, an element whose surface area of the surface of the body of the surface-mounted IC facing the built-in substrate 11 is less than 12 mm ² is called a small-sized element.

In small-sized elements, even if thermal expansion and contraction occur, the absolute values of thermal expansion and contraction are small, so large stress is not applied to the solder portion where the element is fixed onto the built-in substrate 11. For this reason, reduced heat shock resistance is rarely an issue in small-sized elements. Also, even if there is a gap between the built-in substrate 11 and the molded resin 12 in the area surrounding the small-sized element, it is thought that this will not have a significant effect on the heat shock resistance.

On the other hand, for larger elements, the absolute values of thermal expansion and thermal contraction are large, so that large stress is applied to the solder portion where the element is fixed onto the built-in substrate 11. Furthermore, the presence of gaps between the built-in substrate 11 and the molded resin 12 around the large element reduces heat shock resistance. The large element is fixed onto the built-in substrate 11 with solder, but the position of the large element is also fixed by the close contact between the built-in substrate 11 and the molded resin 12 around the large element. Therefore, if there are gaps between the built-in substrate 11 and the molded resin 12 around the large element, the force fixing the large element is weakened, and the large element can be displaced by thermal expansion and thermal contraction due to heat shock. As a result, large stress is applied to the solder portion due to thermal expansion and thermal contraction, causing cracks.

Also, even for large-sized elements, when the pin spacing between adjacent pins is 1 mm or more, the heat shock resistance tends to be lower than when the pin spacing is less than 1 mm. This is because the wider the pin spacing, the greater the displacement due to thermal expansion and contraction.

3 is a top view showing a schematic example of the configuration of the built-in board constituting the electric motor according to the first embodiment. In the example of FIG. 3, the built-in board 11 is a disk-shaped board having a rotating shaft through hole 35 penetrating in the thickness direction through which the rotating shaft 31 of the electric motor 1 passes at the center. The built-in board 11 is a board called a printed circuit board, and is a plate-shaped member made of an insulating material, with wiring arranged on the surface of the plate-shaped member or inside in addition to the surface. Solder resist 111, which is an insulating material, is applied to the surface of the plate-shaped member on which the wiring is arranged, and a footprint 112 of a conductive material is arranged at the mounting position of the surface-mounted element. The footprint 112 is an electrode layer that connects the wiring of the built-in board 11 and the pin of the surface-mounted element via solder. The built-in board 11 may have a through hole penetrating in the thickness direction. The area of the built-in board 11 where the surface-mounted element is mounted is called the element mounting area. The element mounting area is an area that includes the entire surface mount element and the footprint 112 that is provided to correspond to the surface mount element, and is a rectangular area in the example of FIG. 3. A specified surface mount element is mounted in the element mounting area. Examples of surface mount elements are surface mount ICs 83 such as power ICs 80, which are active elements, and chip resistors 84, which are passive elements.

The built-in substrate 11 has an adhesion layer 2 disposed between the built-in substrate 11 and the molded resin 12 so as to surround the surface-mounted element. The adhesion layer 2 is a layer that enhances the adhesion between the built-in substrate 11 and the molded resin 12 when the built-in substrate 11 is integrally molded with the molded resin 12. The adhesion layer 2 is made of a non-insulating material that has a higher adhesion to the molded resin 12 than the adhesion between the solder resist 111 that constitutes the surface of the built-in substrate 11 and the molded resin 12. In other words, the adhesion layer 2 is made of a material that has a high adhesion to the built-in substrate 11, particularly the solder resist 111, and also has a high adhesion to the molded resin 12. An example of such an adhesion layer 2 is silk. Silk is a material that prints signs, including characters and marks of specifications of the surface-mounted element, on the built-in substrate 11. Silk is designed to have a high adhesion to the solder resist 111, and therefore has a similar high adhesion to the molded resin 12, making it suitable as the adhesion layer 2. The thickness of the adhesion layer 2 is not particularly limited, but it is desirable for it to be between several μm and 20 μm.

The adhesion layer 2 is arranged so as to surround the surface mount element, but is not arranged in an area where it is not possible to arrange it due to manufacturing constraints of the built-in board 11. In other words, in this specification, "arranged so as to surround the surface mount element" means that it is arranged in an area surrounding the surface mount element, excluding areas where it is not possible to arrange it due to manufacturing constraints of the built-in board 11. In one example, if there is a copper foil exposed part such as a through hole or a test pad in a part around the surface mount element, the adhesion layer 2 is not arranged in the copper foil exposed part, and it is interrupted. In another example, if a sign including a mark and letters is formed by silk around the surface mount element, the adhesion layer 2 is not arranged on the sign. In addition, the adhesion layer 2 is not arranged within a range of a determined distance from the outer shape of the surface mount element, the copper foil exposed part around the surface mount element, etc. An example of the determined distance is 1 mm. The copper foil exposed part corresponds to the conductive layer exposed part.

It is desirable that the area of the adhesion layer 2 arranged to surround the surface-mounted element is equal to or greater than the sum of the areas of the footprints 112 arranged in the element mounting area. This is because if the area of the adhesion layer 2 is less than the sum of the areas of the footprints 112, the adhesion between the built-in substrate 11 and the molded resin 12 around the surface-mounted elements such as the surface-mounted IC 83 and the chip resistor 84 cannot be increased. In other words, it is impossible to realize an adhesion that can withstand heat shock. By making the area of the adhesion layer 2 equal to or greater than the sum of the areas of the footprints 112, the adhesion between the built-in substrate 11 and the molded resin 12 around the surface-mounted element is increased, and the occurrence of gaps between the built-in substrate 11 and the molded resin 12 is suppressed. In other words, the surface-mounted element is firmly fixed between the built-in substrate 11 and the molded resin 12. As a result, even if thermal expansion and thermal contraction are repeated, the built-in substrate 11 and the molded resin 12 are firmly fixed by the adhesion layer 2. This fixes the surface-mounted IC 83 between the built-in substrate 11 and the molded resin 12, preventing damage to the pins 832, which are the electrodes of the surface-mounted IC 83. In other words, the heat shock resistance can be improved.

The adhesion layer 2 is intended to increase the adhesion between the built-in substrate 11 and the molded resin 12, and is therefore preferably arranged in a strip rather than a line. In other words, if the adhesion layer 2 is arranged in a line, the contact area of the adhesion layer 2 with the built-in substrate 11 and the molded resin 12 is small, and the adhesion between the built-in substrate 11 and the molded resin 12 cannot be made as desired. Taking a surface-mounted IC 83 as an example of a surface-mounted element, if the length of the adhesion layer 2 in the direction perpendicular to the outer side of the body 831 of the surface-mounted IC 83 and the length of the footprint 112 are referred to as the width, it is desirable that the width of the adhesion layer 2 be 1.5 times or more the width of the footprint 112. The same applies when the surface-mounted element is a chip resistor 84.

Furthermore, in the region along the side of the rectangular body 831 of the surface mount IC 83 where the pins 832 are not provided, the adhesion layer 2 is provided in a region longer than the length of the side of the body 831 where the pins 832 are not provided, with a width at least 1.5 times the width of the footprint 112. In this way, in the first embodiment, the adhesion layer 2 is disposed without any gaps in the region around the surface mount IC 83 excluding the body 831 and footprint 112 of the surface mount IC 83.

The adhesion layer 2 is provided around the surface mount elements, but may be provided around all surface mount ICs 83, or may be provided around surface mount ICs 83 that have a body 831 of a specified size or larger. As described above, heat shock is not a major problem for small surface mount ICs 83, so the adhesion layer 2 may not be provided around small surface mount ICs 83, and may be provided around large surface mount ICs 83.

Alternatively, larger surface mount ICs 83 with four or more pins 832 tend to have weaker heat shock resistance than smaller surface mount ICs 83 with three or fewer pins 832, such as Hall ICs. For this reason, the adhesion layer 2 may be arranged in a band around a surface mount IC 83 with four or more pins 832. Also, the adhesion layer 2 may not be arranged around a surface mount IC 83 with three or fewer pins 832.

When the surface mount element is a high-voltage compatible surface mount IC 83, the spacing between adjacent pins may be as wide as 1 mm or more in one example. In this case, it is more effective to apply adhesion layer 2 to the area between adjacent pins 832 as in the surface mount IC 83 in Figure 3. When the pin spacing is wide, the number of pins 832 is small relative to the body 831, so the absolute value of thermal expansion and thermal contraction of each pin 832 becomes large, and the stress on the solder connecting the pin 832 and the footprint 112 becomes large. As a result, surface mount ICs 83 with a wide spacing between adjacent pins of 1 mm or more tend to have reduced heat shock resistance.

FIG. 4 is a diagram showing an example of a state in which a surface-mounted IC is mounted on a built-in substrate constituting an electric motor according to the first embodiment. FIG. 4 shows an example in which a surface-mounted IC 83A is mounted on a built-in substrate 11, in which the adjacent pin interval of the pins 832a arranged on one side of the body 831a is less than 1 mm, and the adjacent pin interval of the pins 832b arranged on the other side is 1 mm or more. As shown in FIG. 4, when the adjacent pin interval is less than 1 mm, due to manufacturing constraints such as the minimum width at which the adhesion layer 2 can be formed, it is not possible to form an adhesion layer 2 between adjacent pins 832a. On the other hand, when the adjacent pin interval is 1 mm or more, due to manufacturing constraints, it is possible to form an adhesion layer 2, so an adhesion layer 2A is also formed between adjacent pins 832b.

In the example shown in FIG. 4, the stress applied to the solder (not shown) connecting each pin 832a with an adjacent pin interval of less than 1 mm to the footprint 112 is smaller than the stress applied to the solder connecting each pin 832b with an adjacent pin interval of 1 mm or more to the footprint 112. Therefore, even if the adhesion layer 2 is not formed between the adjacent pins 832a, the built-in substrate 11 and the molded resin 12 are firmly fixed by the adhesion layer 2 arranged around the surface-mounted IC 83A near the pin 832b. Therefore, the heat shock resistance can be made to a desired value or more. As described above, the solder connecting the pin 832b with an adjacent pin interval of 1 mm or more to the footprint 112 is subjected to a larger stress than the solder connecting each pin 832a with an adjacent pin interval of less than 1 mm to the footprint 112, but the adhesion layer 2A arranged between the pins 832b increases the adhesion between the built-in substrate 11 and the molded resin 12, and the heat shock resistance can be made to a desired value or more.

If there is a distance between the bottom surface of the body 831a of the surface-mounted IC 83A and the footprint 112, the adhesion layer 2 may also be disposed between the footprint 112 and the portion facing the body 831a of the surface-mounted IC 83A.

As shown in FIG. 3, the surface mount element may be not only a surface mount IC 83 but also a chip resistor 84. FIG. 5 is a cross-sectional view showing an example of the structure of a chip resistor. The chip resistor 84 has a plate-shaped ceramic substrate 841 extending in one direction, a resistor 842 provided on the upper surface of the ceramic substrate 841, and a pair of electrodes 843 provided at both ends in the longitudinal direction, which is the extension direction of the ceramic substrate 841. The electrode 843 contacts the end of the resistor 842 on the upper surface of the ceramic substrate 841 at the end in the longitudinal direction of the ceramic substrate 841, and is arranged in close contact with the surface of the ceramic substrate 841 up to a predetermined position on the lower surface of the ceramic substrate 841. In other words, the electrode 843 is provided so as to cover the side of the end in the longitudinal direction of the ceramic substrate 841 and a part of the upper surface and lower surface in a C-shape.

As shown in FIG. 5, the chip resistor 84 has electrodes 843 on the side surfaces at both ends in the longitudinal direction, and no electrodes are provided on the side surfaces along the longitudinal direction. Therefore, compared to passive elements such as chip capacitors that have electrodes on the side surfaces along the longitudinal direction, the electrodes 843 of the chip resistor 84 are more likely to peel off.

6 is a cross-sectional view showing an example of the state of a chip resistor when a gap occurs between the built-in substrate and the molded resin. FIG. 6 is a cross-sectional view showing an enlarged view of region A in FIG. 5. As shown in FIG. 6, a gap 845 may be formed between the resistor 842 and the electrode 843 on the upper surface of the chip resistor 84. When the built-in substrate 11 on which such a chip resistor 84 is mounted is insert-molded, the molded resin 12 enters the gap 845. In such a case, the molded resin 12 that has entered the gap 845 between the resistor 842 and the electrode 843 of the chip resistor 84 is lifted up by thermal expansion and contraction of the heat shock. As a result, the molded resin 12 that has entered the gap 845 becomes caught by the electrode 843, and the electrode 843 is also lifted up, causing it to peel off from the resistor 842, and the resistor may become electrically open.

By applying the adhesion layer 2 in a strip shape so as to surround the chip resistor 84, as in the case of the surface mount IC 83, the degree of adhesion between the built-in substrate 11 and the molded resin 12 around the chip resistor 84 is increased, and gaps 845 are less likely to occur between the built-in substrate 11 and the molded resin 12. As a result, even if the molded resin 12 gets into the gaps 845 between the resistor 842 and the electrodes 843 of the chip resistor 84, the molded resin 12 is in close contact with the built-in substrate 11 around the chip resistor 84, so the molded resin 12 does not move in a direction away from the built-in substrate 11. As a result, it is possible to suppress the occurrence of electrical open circuits caused by peeling of the electrodes 843 of the chip resistor 84.

In addition, there may be exposed copper foil areas such as through holes and test pads around the chip resistor 84. In this way, the adhesion layer 2 is not disposed on the exposed copper foil areas around the chip resistor 84. In other words, there is no problem even if the adhesion layer 2 has some discontinuous areas. Also, in the case of the chip resistor 84, it is effective if the area of the adhesion layer 2 around the chip resistor 84 is equal to or greater than the sum of the areas of the footprints 112 in the element mounting area of the chip resistor 84.

In addition, the electrodes 843 tend to peel off easily as the chip resistor 84 becomes smaller, and this tendency is particularly strong in chip resistors 84 that are smaller than the so-called 1005 size, which has a long side of 1.0 mm and a short side of 0.5 mm. For this reason, in the case of chip resistors 84, it is desirable to place an adhesion layer 2 around chip resistors 84 that are 1005 size or smaller. Of course, there is no problem with placing an adhesion layer 2 around chip resistors 84 that are larger than the 1005 size.

As described above, the adhesion layer 2 is arranged in a band around the surface-mounted element, except in areas where it cannot be arranged due to manufacturing constraints on the built-in substrate 11. Furthermore, if the spacing between adjacent pins is 1 mm or more, the adhesion layer 2A is also arranged in the areas between the pins 832b, unless there are constraints.

FIG. 7 is a top view showing another example of a state in which elements are mounted on the built-in substrate constituting the electric motor according to the first embodiment. In FIG. 3, the adhesion layer 2 is arranged around the surface-mounted elements including the surface-mounted IC 83 and the chip resistor 84, but in FIG. 7, the adhesion layer 2 is arranged over the entire surface of the built-in substrate 11, including the element mounting area of the surface-mounted elements. In this case, as described above, the adhesion layer 2 is not arranged on the exposed copper foil areas such as through holes and test pads. In this way, by increasing the area on the built-in substrate 11 where the adhesion layer 2 is arranged, it is possible to further increase the adhesion between the built-in substrate 11 and the molded resin 12, and the surface-mounted elements sandwiched between the built-in substrate 11 and the molded resin 12 can be more firmly fixed.

As an example, the adhesion layer 2 can be made of silk as described above. When the adhesion layer 2 is made of silk, it can have markings on it that indicate the specifications of the surface mounted components, the arrangement direction of the mounted components, and the like. In this case, the markings can be formed as cut-out characters on the silk placed over the entire surface of the built-in substrate 11.

Also, depending on the material of the silk, there are restrictions on the application area due to the UL standard, which is a product safety standard established by Underwriters Laboratories Inc. (UL). Fig. 8 is a top view showing another example of a state in which no elements are mounted on the built-in substrate constituting the electric motor according to the first embodiment. In the example of Fig. 8, silk, which is the adhesion layer 2, is not arranged in the element mounting area of the built-in substrate 11. That is, silk is not arranged on the built-in substrate 11 at the facing portion 3A of the body 831 of the surface-mounted IC 83 and the facing portion 3B of the body of the chip resistor 84. The body of the chip resistor 84 corresponds to the ceramic substrate 841.

Even if silk is placed in areas that do not come into contact with the molded resin 12, such as the area facing the body of the surface-mounted element, there is no effect of improving heat shock resistance. For this reason, if there are restrictions on the area where silk can be applied, as shown in Figure 8, it is possible not to apply silk to the area facing the body of the surface-mounted element. In addition, as shown in Figure 3, restrictions on the application area can be avoided by not applying silk to positions away from the surface-mounted element, which has low heat shock resistance.

The adhesion layer 2 is printed at a predetermined position on the surface of the built-in substrate 11 by a method such as screen printing. The built-in substrate 11 is a typical printed circuit board, and solder resist 111 is applied to the area excluding the exposed copper foil area, footprint 112, etc. Surface mount elements are mounted on the built-in substrate 11 on which the adhesion layer 2 is printed. The built-in substrate 11 on which the surface mount elements are mounted is integrally molded with the stator 20 and other components that constitute the electric motor 1 using molded resin 12.

In Patent Document 1, silk with a first pattern is formed so as to surround a rectangular area including the body and pad of the Hall IC. The width of the silk with the first pattern is about 1/7 or less of the longitudinal length of the pad surrounded by the first pattern. This is to allow it to function as a dike that prevents the solder from flowing out beyond the first pattern. Even if silk with a width sufficiently small compared to the longitudinal length of such a pad is placed around the Hall IC, the effect of increasing the adhesion between the control board and the molded resin is very small. Therefore, in Patent Document 1, if the Hall IC is replaced with a large surface-mounted IC such as a power IC, there is a high possibility that a gap will occur between the control board and the molded resin due to heat shock.

On the other hand, in the first embodiment, the adhesion layer 2 is disposed around the surface-mounted element of the built-in substrate 11 on the side where the molded resin 12 comes into contact, and the built-in substrate 11 is integrally molded with the molded resin 12. The adhesion layer 2 enhances the adhesion between the built-in substrate 11 and the molded resin 12, and therefore the adhesion between the built-in substrate 11 and the molded resin 12 can be enhanced compared to the case where the adhesion layer 2 is not present. As a result, the built-in substrate 11 and the molded resin 12 are firmly fixed around the surface-mounted element, and gaps are unlikely to occur between the two, and the surface-mounted element is fixed between the built-in substrate 11 and the molded resin 12. Even if thermal expansion and thermal contraction are repeated, the surface-mounted element is fixed between the built-in substrate 11 and the molded resin 12, so that the occurrence of cracks in the solder connecting the surface-mounted element and the footprint 112 can be suppressed, and the heat shock resistance can be improved.

In this way, the electric motor 1 according to the first embodiment includes a rotor 30, a stator 20 provided on the outer periphery of the rotor 30, an internal substrate 11 that controls the drive of the rotor 30 and on which surface-mounted elements are mounted, and a molded resin 12 that is integrally molded with the internal substrate 11. The internal substrate 11 has an adhesion layer 2 that is disposed between the internal substrate 11 and the molded resin 12 so as to surround the surface-mounted elements, and the area of the adhesion layer 2 is arranged in the element mounting area, which is the area in which the surface-mounted elements are mounted, and is greater than or equal to the total area of the footprint 112, which is an electrode layer that is connected to the electrodes of the surface-mounted elements via solder. This has the effect of suppressing the occurrence of cracks due to heat shock in the solder that connects the electrode layer of the internal substrate 11 molded with the molded resin 12 to the electrodes of the surface-mounted elements, compared to the conventional case.

Embodiment 2.
Fig. 9 is a cross-sectional view showing a schematic example of the configuration of an electric motor according to embodiment 2. The same components as those in embodiment 1 are given the same reference numerals, and detailed description thereof will be omitted. The electric motor 1A shown in Fig. 9 has the built-in substrate 11, molded resin 12, stator 20 having stator core 21 and winding group 22, rotating shaft 31, magnet 40, power IC 80, and heat sink 6, which are described in embodiment 1.

The heat sink 6 is provided to further improve heat dissipation and dissipates heat. The heat sink 6 is made of a metal such as aluminum. The heat sink 6 is placed on the side of the built-in substrate 11 opposite the stator 20 via the molded resin 12. The heat sink 6 may be integrally molded with the built-in substrate 11 and the molded resin 12, or the heat sink 6 may be attached after the built-in substrate 11 and the molded resin 12 are integrally molded. When attaching the heat sink 6 after integral molding, it is desirable to place a thermally conductive sheet or thermally conductive grease between the heat sink 6 and the molded resin 12 in order to reduce the contact thermal resistance with the molded resin 12.

In the second embodiment, the heat sink 6 is provided on the side of the built-in substrate 11 opposite the stator 20. This improves the heat dissipation performance of the built-in substrate 11 and improves the heat shock resistance between the built-in substrate 11 and the molded resin 12.

Embodiment 3.
10 is a diagram showing a schematic diagram of an example of the configuration of an air conditioner according to embodiment 3. An air conditioner 200 includes an indoor unit 210 and an outdoor unit 220 connected to the indoor unit 210. The indoor unit 210 includes the motor 1 described in embodiment 1 or the motor 1A described in embodiment 2, an indoor unit board 211, and an indoor unit blower (not shown). The outdoor unit 220 includes an outdoor unit blower 223.

The outdoor unit blower 223 and the indoor unit blower each incorporate the electric motor 1 described in embodiment 1 or the electric motor 1A described in embodiment 2 as their drive source. In particular, when the air conditioner 200 is for commercial use, high output and high heat dissipation performance are required, so the application of the electric motors 1 and 1A described in

embodiments

1 and 2 increases the heat dissipation effect.

In addition to the air conditioner 200, the electric motors 1 and 1A can also be mounted and used in ventilation fans, home appliances, machine tools, etc.

In this way, according to the third embodiment, the electric motors 1 and 1A described in the first and second embodiments are applied to the air conditioner 200, so that the temperature rise of the built-in board 11 can be significantly suppressed.

The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or the embodiments may be combined with each other. In addition, parts of the configurations may be omitted or modified without departing from the spirit of the invention.

1, 1A electric motor, 2, 2A adhesive layer, 3A, 3B opposing parts, 6 heat sink, 10 molded stator, 11 built-in board, 12 molded resin, 13 lead wire, 14 lead outlet, 20 stator, 21 stator core, 22 winding group, 22U U-phase winding, 22V V-phase winding, 22W W-phase winding, 23 insulator, 30 rotor, 31 rotating shaft, 32 rotor insulation part, 33 output side bearing, 34 anti-output side bearing, 35 rotating shaft through hole, 40 magnet, 41 connection point, 50 magnetic sensor, 60 bracket, 61 press-fit part, 70 control part, 75 Overcurrent detection resistor, 77 high voltage power supply, 78 low voltage power supply, 79A, 79B, 79C ground, 80 power IC, 81, 81A-81F power transistor, 82 gate drive circuit, 83, 83A surface mount IC, 84 chip resistor, 85 protection circuit, 111 solder resist, 112 footprint, 200 air conditioner, 210 indoor unit, 211 indoor unit board, 220 outdoor unit, 223 outdoor unit blower, 831, 831a body, 832, 832a, 832b pin, 841 ceramic board, 842 resistor, 843 electrode, 845 gap.

Claims

A rotor;
A stator provided on an outer periphery of the rotor;
a control board for controlling the driving of the rotor and on which surface mount devices are mounted;
a mold resin integrally molded with the control board;
Equipped with
the control board has an adhesion layer disposed between the control board and the molding resin so as to surround the surface-mounted device;
An electric motor in which the area of the adhesion layer is greater than or equal to the total area of electrode layers that are disposed in an element mounting area, which is an area where the surface mount element is mounted, and are connected to the electrodes of the surface mount element via solder.
the surface mount device is a surface mount integrated circuit having a plurality of pins;
The electric motor according to claim 1 , wherein the adhesion layer is also disposed between the adjacent pins when the interval between the adjacent pins is 1 mm or more.
The electric motor according to claim 1, wherein the surface-mounted element is a chip resistor having electrodes on both longitudinal ends.
The electric motor according to any one of claims 1 to 3, wherein the adhesion layer is disposed over the entire surface of the control board.
The electric motor according to any one of claims 1 to 3, wherein the adhesion layer is disposed on the entire surface of the control board except for the portion facing the body of the surface-mounted element.
The electric motor according to any one of claims 1 to 5, wherein the adhesive layer is silk.
The electric motor according to any one of claims 1 to 6, wherein the adhesive layer is not disposed on signs including marks and letters formed on the adhesive layer around the surface mount element, on exposed conductive layer portions, or in a position facing the body of the surface mount element and not in contact with the molded resin.
Further comprising a heat sink for dissipating heat;
The electric motor according to claim 1 , wherein the heat sink is disposed on an opposite side of the control board from the stator, with the molding resin interposed therebetween.
An air conditioner equipped with an electric motor according to any one of claims 1 to 8.