Electric motor and air conditioner

Abstract

This electric motor comprises: a rotor; a stator provided to the outer periphery of the rotor; a built-in substrate (11) that controls driving of the rotor and has mounted thereon a surface-mounted component, which is an electronic component; and a mold resin that covers the entirety of the built-in substrate and is integrally molded with the built-in substrate. A substrate hole (86) that penetrates the built-in substrate is disposed in a region other than the region where the surface-mounted component is disposed, and outside the electrical connection position between the surface-mounted component and the built-in substrate, in the upper-surface region of the built-in substrate. A third mold resin that joins a first mold resin disposed on the upper surface of the built-in substrate and a second mold resin disposed on the bottom surface of the built-in substrate is embedded in the substrate hole.

Description

Electric motors and air conditioners

[0001] The present disclosure relates to an electric motor and an air conditioner having a molded resin integrally molded with a built-in substrate.

[0002] In recent years, there has been a demand for higher output fan motors (electric motors for fans) in air conditioners to save energy and improve their heating capacity. To achieve higher output fan motors, 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 has been known in which the built-in substrate including the power IC is integrally molded with resin.

[0003] The printed circuit board described in Patent Document 1 has a through hole formed through the top surface of the printed circuit board to the bottom surface, and a sealing resin part that is sealed on the top surface of the printed circuit board and a coating resin part that covers the bottom surface of the printed circuit board are molded integrally via the through hole.

[0004] Japanese Patent Application Publication No. 10-56097

[0005] However, with the technology of Patent Document 1, the through holes into which the mold resin is poured can only be formed inside the printed circuit board relative to the positions of the bonding wires, which are the positions for electrical connection between the semiconductor element and the printed circuit board. As a result, the larger the printed circuit board, the more likely the mold resin is to peel off from the printed circuit board, which causes the electrical connection between the printed circuit board and the surface-mounted components mounted on the printed circuit board to be easily severed.

[0006] The present disclosure has been made in consideration of the above, and aims to obtain an electric motor that can prevent the electrical connection between an internal board and surface-mounted components mounted on the internal board from being severed, regardless of the size of the internal board placed in the electric motor.

[0007] In order to solve the above-mentioned problems and achieve the object, the electric motor of the present disclosure includes a rotor, a stator provided on the outer periphery of the rotor, a built-in substrate that controls the drive of the rotor and on which surface-mounted components (electronic components) are mounted, and a molded resin that covers the entire built-in substrate and is integrally molded with the built-in substrate. A board hole that penetrates the built-in substrate is arranged in an area of ​​the top surface of the built-in substrate other than the area where the surface-mounted components are arranged and outside the area where the surface-mounted components are electrically connected to the built-in substrate. A third molded resin that joins a first molded resin arranged on the top surface of the built-in substrate to a second molded resin arranged on the bottom surface of the built-in substrate is filled in the board hole.

[0008] The electric motor according to the present disclosure has the advantage of being able to prevent electrical disconnection between the built-in board and the surface-mounted components mounted on the built-in board, regardless of the size of the built-in board placed in the electric motor.

[0009] FIG. 1 is a diagram showing an example of the configuration of an electric motor according to embodiment 1. FIG. 1 is a diagram showing an example of the circuit configuration of an internal substrate provided in an electric motor according to embodiment 1. FIG. 2 is a diagram showing an example of the configuration of an internal substrate and molded resin provided in an electric motor according to embodiment 1. FIG. 3 is a diagram showing an example of the arrangement of board holes arranged in an internal substrate provided in an electric motor according to embodiment 1. FIG. 4 is a diagram showing an example of the structure of a chip resistor mounted on an internal substrate of an electric motor according to embodiment 1. FIG. 5 is a diagram showing an example of the state of a chip resistor when a gap occurs between the internal substrate and molded resin. FIG. 6 is a diagram showing an example of the configuration of an internal substrate and molded resin provided in an electric motor of a comparative example. FIG. 7 is a diagram showing an example of the arrangement of board holes arranged in an internal substrate provided in an electric motor according to embodiment 2. FIG. 8 is a diagram showing an example of the arrangement of board holes arranged in an internal substrate provided in an electric motor according to embodiment 3.

[0010] Hereinafter, an electric motor and an air conditioner according to an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0011] 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 of embodiment 1 is not limited to a three-phase electric motor.

[0012] The electric motor 1 is a brushless DC (Direct Current) motor. FIG. 1 shows a partial cross-sectional structure for the purpose of explaining the configuration of the electric motor 1. The electric motor 1 includes a rotor 30, a stator 20, an internal substrate 11 serving as a control substrate, and a 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 internal substrate 11 includes a substrate circuit that controls the drive of the rotor 30. Surface-mounted components such as a surface-mounted IC (surface-mounted integrated circuit) 83 are disposed on the upper surface of the internal substrate 11 (the surface on the right side of the internal substrate 11 shown in FIG. 1 ). The surface-mounted IC 83 is an electronic component such as an IC chip disposed on the upper surface of the internal substrate 11.

[0013] The stator 20, built-in substrate 11, and molded resin 12 are fixed together by a molded stator 10. The molded stator 10 is formed by integrally molding the stator 20 and the built-in substrate 11 as a whole. That is, the stator 20 and the built-in substrate 11 are fixed together by the molded stator 10. 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 molded separately as a single unit. In this case, the integrally molded stator 20 and the integrally molded built-in substrate 11 are joined together. This improves the heat dissipation of the power IC 80 (described later) and other components, making it possible to suppress temperature increases.

[0014] The molded stator 10 is provided with substrate pressing holes 51. In the electric motor 1, the built-in substrate 11 is pressed down by mold pins (not shown) that are passed through the substrate pressing holes 51, thereby suppressing distortion of the built-in substrate 11 due to molding pressure during integral molding. The substrate pressing holes 51 are provided in locations on the built-in substrate 11 where there are no patterns. This is to prevent the patterns from being damaged and broken during integral molding, and to improve safety by preventing the live parts (patterns on the built-in substrate 11) from coming into contact with the outside air.

[0015] The built-in substrate 11 is a printed circuit board. The built-in substrate 11 has a base material in which copper foil is arranged on both sides of an insulating base material, and the copper foil other than the desired pattern is removed by etching to form a pattern. Etching methods are broadly divided into printing and photography. The printing method is cheaper than the photography method, but the photography method has better dimensional accuracy than the printing method.

[0016] The built-in substrate 11 is formed by stacking multiple layers. The built-in substrate 11 has through-holes for electrically connecting the patterns on each layer. The through-holes are created by drilling holes in the built-in substrate 11 and then copper plating the wall surfaces of the holes. While the photography method allows for the selection of whether or not to copper-plat each hole, the printing method results in copper-plated through-holes in all holes. When forming holes without copper plating (hereinafter referred to as non-through holes) using the printing method, the built-in substrate 11 must be punched out in the die punching process at the final stage of the manufacturing process. In this case, if a pattern exists near the non-through hole, cracks may occur in the pattern, causing disconnections or other problems. Therefore, a distance of at least a specific distance must be maintained between the non-through hole and the pattern. The specific distance is, for example, the same distance as the thickness of the built-in substrate 11. For example, if the thickness of the built-in substrate 11 is 1.6 mm, a distance of at least 1.6 mm must be maintained between the non-through hole and the pattern.

[0017] After the through holes are formed in the built-in substrate 11, solder resist is applied to the built-in substrate 11 in areas other than those where solder has been applied. Then, silk, which depicts specifications, the board model number, a diagram showing the component positions, and the like, is applied to the built-in substrate 11. The silk is, for example, an ink that has high adhesion to organic substances such as solder resist ink.

[0018] The stator 20 has a plurality of stator cores 21, insulators 23 integrally molded 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.

[0019] In the electric motor 1, the stator 20 is formed by winding the windings of the winding group 22 into 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.

[0020] 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.

[0021] The bracket 60 is fitted into the inner periphery of the molded stator 10 so as to close 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.

[0022] The built-in substrate 11 is provided with a circuit including a power IC 80 , a control unit (a control unit 70 described later), and a magnetic sensor 50 such as a Hall IC that detects the position of the rotor 30 .

[0023] 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 80 on the built-in board 11 is connected to the windings of the winding group 22 via winding terminals. The built-in board 11 has a lead outlet 14 from which lead wires 13 are drawn 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. For example, the lead wires 13 are connected to a board on the unit side of an air conditioner, such as an indoor unit board (indoor unit board 211, described later). Components such as an operational amplifier, a comparator, a regulator, a diode, a resistor, a capacitor, an inductor, and a fuse are also disposed on the built-in board 11.

[0024] The built-in substrate 11 has, for example, a circular plate shape with a through-hole formed in the center. However, the built-in substrate 11 may have a shape other than a circular plate shape, such as a semicircular shape or a rectangular shape. A 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.

[0025] The rotor 30 has a rotor insulating 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 made of a cylindrical permanent magnet. The magnet 40 is fixed to the rotating shaft 31.

[0026] Magnet 40 is produced by injection molding, in a non-vacuum state, a bonded magnet made by mixing a ferrite magnet or a rare earth magnet with a thermoplastic resin material. Examples of rare earth magnets are samarium-iron-nitrogen magnets and neodymium magnets. A magnet is incorporated into a mold for injection molding magnet 40, and magnet 40 is molded while applying orientation. Magnet 40 may also be a sintered magnet.

[0027] The magnet 40 has, in the axial direction of the rotating shaft 31, a sensor magnet portion that is the portion close to the magnetic sensor 50, and a main magnet portion that is the portion other than the sensor magnet portion. The sensor magnet portion causes the magnetic sensor 50 to detect the position of the rotor 30. The main magnet portion generates a rotational force in the rotor 30 in accordance with the magnetic flux generated by the winding group 22.

[0028] The outer diameter of the magnet 40 on the magnetic sensor 50 side of the built-in substrate 11 is smaller than the outer diameter of other portions. That is, the outer diameter of the sensor magnet portion of the magnet 40 is smaller than the outer diameter of the main magnet portion. This shape of the magnet 40 makes it easier for magnetic flux to flow into the magnetic sensor 50 mounted on the built-in substrate 11. The magnetic sensor 50 is positioned far from the winding group 22, that is, near the rotating shaft 31, to minimize the influence of the magnetic flux generated from the winding group 22 of the stator 20.

[0029] Although FIG. 1 shows a case where the main magnet section and the sensor magnet section are configured by a single magnet 40, the main magnet section and the sensor magnet section may be configured by separate magnets.

[0030] The magnetic sensor 50 may be configured using a Hall IC that outputs a digital signal, or may be configured using a Hall element that outputs an analog signal. That is, the magnetic sensor 50 may be configured to detect the position of the rotor 30 using a Hall IC, or may be configured to detect the position of the rotor 30 using a Hall element.

[0031] Furthermore, the Hall IC may be a first-type Hall IC that detects the position of the rotor 30 using a first method described later, or a second-type Hall IC that detects the position of the rotor 30 using a second method described later.

[0032] In a first-type Hall IC, the sensor section and the amplifier section are configured on separate semiconductor chips. In this first-type Hall IC, the sensor section is configured on a semiconductor other than silicon, and the amplifier section is configured on silicon. Hereinafter, the first-type Hall IC will be referred to as a non-silicon Hall IC. In a second-type Hall IC, the sensor section and the amplifier section are configured on a single silicon semiconductor chip.

[0033] A non-silicon Hall IC incorporates two semiconductor chips (a non-silicon semiconductor chip for the sensor section and a silicon semiconductor chip for the amplifier section), and the sensor section 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 section of a non-silicon Hall IC. Compared to silicon semiconductors, this non-silicon semiconductor has advantages such as better sensitivity and smaller offset due to stress distortion.

[0034] The electric motor 1 may be provided with a heat sink that dissipates heat to improve heat dissipation. The heat sink is made of a metal such as aluminum. The heat sink is disposed on the opposite side of the stator 20 from the built-in substrate 11 via the molded resin 12. The heat sink may be integrally molded with the built-in substrate 11 using the molded resin 12, or the heat sink may be attached after the built-in substrate 11 and the molded resin 12 are integrally molded. If the heat sink is attached after integral molding, it is desirable to place a thermally conductive sheet or thermally conductive grease between the heat sink and the molded resin 12 to reduce the contact thermal resistance with the molded resin 12.

[0035] Next, the circuit configuration of the built-in substrate 11 shown in Fig. 1 will be described. Fig. 2 is a diagram showing an example of the circuit configuration of the built-in substrate provided in the electric motor according to the first embodiment. Fig. 2 shows the built-in substrate 11, the winding group 22, and the magnetic sensor 50. The built-in substrate 11 includes an overcurrent detection resistor 75, a control unit 70, and a power IC 80.

[0036] The control unit 70 is connected to a higher-level system, a gate drive circuit 82, a ground 79A, and the magnetic sensor 50. The control unit 70 is also connected to a low-voltage power supply 78.

[0037] 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.

[0038] The gate drive circuit 82 includes a protection circuit 85. The protection circuit 85 is connected to the connection point 41. The protection circuit 85 is connected to the ground 79C via the connection point 41 and the overcurrent detection resistor 75.

[0039] 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 the ground 79C via the connection point 41 and the overcurrent detection resistor 75. The grounds 79A to 79C are common grounds of the same potential.

[0040] The power transistor 81 includes six power transistors 81A to 81F. In the power transistor 81, the six power transistors 81A to 81F are configured separately. That is, the six power transistors 81A to 81F are configured as chips, which are separate components.

[0041] The gate drive circuit 82 may be configured as a single IC, or may be configured as three separate three-phase ICs. The gate drive circuit 82 and the control unit 70 may also be configured as a single IC. The control unit 70 may also be configured as a single IC. For example, the control unit 70 may be configured as a control IC, which is a dedicated IC that does not require software, or as a microcomputer. Hereinafter, a microcomputer will be 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 a single IC, or the gate drive circuit 82, the protection circuit 85, and the control unit 70 may be configured as a single IC.

[0042] The power transistors 81A to 81F are configured with superjunction MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), planar MOSFETs, IGBTs (Insulated Gate Bipolar Transistors), etc. Because a large current flows through the power transistors 81A to 81F, they generate a lot of heat, which can cause heat dissipation problems.

[0043] 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. Note that 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 in the winding group 22. In other words, the electric motor 1 is not limited to a case in which the magnetic pole position (rotor magnetic flux position) of the rotor 30 is detected by the magnetic sensor 50, and the electric motor 1 may be controlled sensorlessly by estimating the magnetic pole position from the current and voltage in the winding group 22.

[0044] Furthermore, the built-in board 11 may use a shunt resistor and a current sensor to detect the current, and may amplify the current signal obtained by the use of an operational amplifier, etc. Furthermore, the built-in board 11 may use a comparator to generate a signal from the current signal to the control unit 70 for overcurrent protection.

[0045] In the built-in substrate 11, the voltage (e.g., 15 V) that drives the gates of the power transistors 81A to 81F may differ from the microcomputer power supply voltage (e.g., 5 V) that drives the control unit 70 such as a microcomputer. In this case, the electric motor 1 uses a regulator to generate one power supply from another power supply supplied from an external source. In one example, a 15 V power supply is supplied to the built-in substrate 11 from an external source, and the regulator generates a 5 V power supply and supplies it to the built-in substrate 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.

[0046] 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 the AC voltage to winding group 22 of 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.

[0047] That is, the power transistor 81A is the power transistor of the upper arm of the U phase, the power transistor 81B is the power transistor of the upper arm of the V phase, and the power transistor 81C is the power transistor of the upper arm of the W phase. Also, the power transistor 81D is the power transistor of the lower arm of the U phase, the power transistor 81E is the power transistor of the lower arm of the V phase, and the power transistor 81F is the power transistor of the lower arm of the W phase.

[0048] As described above, the power transistor 81 has a plurality of power transistors 81A to 81C in the upper arm and a plurality of power transistors 81D to 81F in the lower arm. In the first embodiment, the power transistors in the upper arm or the 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 or the lower arm that switches less frequently is arranged on the top surface of the built-in substrate 11.

[0049] 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.

[0050] The gate drive circuit 82 controls the on and off of the power transistors 81A to 81F in accordance with a switching signal received from the control unit 70.

[0051] Three magnetic sensors 50 are arranged around the winding group 22. Each of the three magnetic sensors 50 outputs a magnetic pole position signal, which is a signal corresponding to the position of the rotor 30, to the control unit 70.

[0052] Furthermore, 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 the power transistors 81A to 81F of the power transistor 81 to prevent element destruction due to high temperatures.

[0053] The overcurrent detection resistor 75 is connected to a lower arm switch (not shown) of the power transistors 81D to 81F and is part of the protection circuit 85. The protection circuit 85 is a circuit that performs overcurrent protection, overheat protection, and overvoltage and undervoltage protection for the power supply. The protection circuit 85 monitors the voltage of the overcurrent detection resistor 75 and, when the voltage of the overcurrent detection resistor 75 exceeds a specific value, forcibly turns off the power transistors 81A to 81F, thereby suppressing overcurrent flow through the winding group 22 and realizing overcurrent protection. The overcurrent detection resistor 75, which is an overcurrent detection unit, may be built into the control unit 70 or the gate drive circuit 82.

[0054] The built-in substrate 11 may be provided 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 to 81F to achieve overheat protection.

[0055] The control unit 70 performs pulse width modulation (PWM) control on the power transistors 81A to 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.

[0056] Electric motor 1, which is a brushless DC motor, obtains rotational power by switching six power transistors 81A to 81F (in the case of a three-phase motor) at appropriate timing according to the magnetic pole position of magnet 40 of rotor 30. The switching signals used for this switching are generated by control unit 70. The operating principle of this electric motor 1 will now be described.

[0057] In electric motor 1, control unit 70 estimates the magnetic pole position of rotor 30 based on the magnetic pole position signal from magnetic sensor 50 or the current value of the current flowing through winding group 22. Control unit 70 generates switching signals for switching power transistors 81A-81F in accordance with the magnetic pole position of rotor 30 and a speed command signal output from a higher-level system. Gate drive circuit 82 switches power transistors 81A-81F on and off in accordance with the switching signals generated by control unit 70.

[0058] The energization methods used by the electric motor 1 include 120° energization control, 150° energization control, and sine wave energization control.

[0059] Taking 120° conduction control as an example, the timing of switching on and off the six power transistors 81A to 81F is the same as the rising and falling edges of the detection signals from the three Hall ICs. Therefore, in 120° conduction control, the control unit 70 can be configured as a combinational circuit that does not require a clock.

[0060] On the other hand, in the case of control that requires estimation of the magnetic pole position, such as 150° energization control, sinusoidal wave energization control, phase control, and sensorless control, the control unit 70 is configured with a complex digital circuit including a clock. In one example of estimation of the magnetic pole position, the timing between each rise and fall of the detection signals from three Hall ICs is precisely estimated.

[0061] Sensorless control is control that does not use the magnetic sensor 50. In sensorless control, the magnetic pole position is estimated from a current value detected by a current detection resistor, a current detection transformer, etc. In sensorless control, signals detected by the current detection resistor, the current detection transformer, etc. may be amplified using an operational amplifier, etc., as necessary.

[0062] As described above, the control unit 70 adjusts the voltage applied to the winding group 22 by PWM control of the power transistors 81A to 81F. In the motor 1, there are cases where only one of the upper and lower arms is switched to reduce loss due to switching of the power transistor 81.

[0063] Next, we will explain the details of the configuration of the built-in board 11 in the electric motor 1. The above-mentioned elements, such as the control IC (controller 70), power IC 80, Hall IC, Hall element, operational amplifier, comparator, regulator, and diode, are configured using surface-mounted ICs 83 to reduce the cost of individual components by miniaturizing them and to reduce the cost of mounting them on the board. The surface-mounted ICs 83 are an example of surface-mounted elements.

[0064] As described above, in one example, molded stator 10 is formed by insert-molding stator 20 and built-in substrate 11 into one body using mold resin 12. Built-in substrate 11, on which elements including surface-mounted ICs 83 are mounted, is in close contact with mold resin 12.

[0065] In this way, the surface-mounted IC 83 has a lower heat shock resistance and is more likely to fail to meet the heat shock test standards than an insertion-mounted IC such as an SIP (Single In-line Package) or DIP (Dual In-line Package) in which lead wires inserted into through holes are soldered in the built-in substrate 11 integrally molded with the molded resin 12. In particular, if a gap occurs between the built-in substrate 11 and the molded resin 12 around the surface-mounted IC 83 due to thermal expansion and contraction caused by the heat shock, the heat shock resistance will be reduced.

[0066] A gap occurs between the built-in substrate 11 and the molded resin 12 because the adhesive strength between the built-in substrate 11 and the molded resin 12 is weak. In the first embodiment, in order to improve the adhesive strength between the built-in substrate 11 and the molded resin 12 around the surface-mounted IC 83, a substrate hole (substrate hole 86, described later) is provided in the built-in substrate 11 around the surface-mounted IC 83, and the molded resin 12 is filled into this substrate hole 86. This mechanically connects the molded resin 12 on both sides (top and bottom) of the built-in substrate 11, thereby suppressing the force that causes the molded resin 12 to peel off from the built-in substrate 11. If the size of the substrate hole 86 is small, the adhesive strength between the molded resin 12 on both sides of the built-in substrate 11 is weakened, so it is better for the size of the substrate hole 86 to be as large as possible. The size of the substrate hole 86 is, for example, 0.5 mm 2 in cross section. 2The cross-sectional area here is the cross-sectional area when the board hole 86 is cut along a plane parallel to the top surface of the surface-mounted IC 83, and corresponds to the area of ​​the top surface of the board hole 86. The board hole 86 has a cross-sectional area of ​​0.5 mm 2 Since the size is large, the mold resin 12 on both sides of the built-in substrate 11 can be firmly connected.

[0067] In this way, in embodiment 1, since the molded resin 12 is filled into the substrate hole 86, it is possible to prevent a decrease in the heat shock resistance strength even in the surface-mounted IC 83, and it is possible to satisfy the heat shock test standards.

[0068] It should be noted that chip resistors (chip resistors 84 described later) may be arranged on the built-in substrate 11 together with the surface-mounted ICs 83 or instead of the surface-mounted ICs 83. That is, surface-mounted electronic components such as the surface-mounted ICs 83 and the chip resistors 84 are mounted on the built-in substrate 11.

[0069] The surface-mounted components mounted on the built-in substrate 11 may be components other than the surface-mounted IC 83 and the chip resistor 84. For example, surface-mounted components such as chip capacitors may be mounted on the built-in substrate 11.

[0070] Next, the configurations of the built-in substrate 11 and molded resin 12 shown in FIG. 1 will be described. FIG. 3 is a diagram showing an example of the configuration of the built-in substrate and molded resin provided in the electric motor according to the first embodiment. FIG. 3 shows a cross-sectional view of the built-in substrate 11 and molded resin 12. At least one of a surface-mounted IC 83 and a chip resistor 84 is arranged on the top surface of the built-in substrate 11 as surface-mounted components. In FIG. 3, the surface on which at least one of the surface-mounted IC 83 and the chip resistor 84 is arranged is the top surface of the built-in substrate 11. Note that at least one of the surface-mounted IC 83 and the chip resistor 84 may also be arranged on the bottom surface of the built-in substrate 11.

[0071] The built-in substrate 11 has a substrate hole 86 penetrating the built-in substrate 11 in a portion of the upper surface area of ​​the built-in substrate 11 other than the area where the surface-mounted ICs 83 or the chip resistors 84 are arranged. Molding resin 12 is poured into the built-in substrate 11 on which at least one of the surface-mounted ICs 83 and the chip resistors 84 is arranged. As a result, the molding resin 12 is embedded in the substrate hole 86, and the molding resin 12 fills the substrate hole 86. Furthermore, the entire surface of the built-in substrate 11 on which at least one of the surface-mounted ICs 83 and the chip resistors 84 is arranged is covered with the molding resin 12, and the entire built-in substrate 11 is integrally molded with the molding resin 12.

[0072] In this way, by filling the substrate holes 86 with the molded resin 12, the molded resin 12 on both sides of the built-in substrate 11 is mechanically connected by the molded resin 12 in the substrate holes 86. Then, by joining the molded resin 12 on the top surface of the built-in substrate 11 and the molded resin 12 on the bottom surface by the molded resin 12 embedded in the substrate holes 86, the force that tries to peel the molded resin 12 from the built-in substrate 11 can be suppressed, and gaps are less likely to form between the built-in substrate 11 and the molded resin 12. This improves the heat shock resistance of the surface-mounted IC 83 and makes it less likely that the electrodes of the chip resistor 84 will peel off.

[0073] Of the molded resins 12, the molded resin 12 arranged on the top surface of the built-in substrate 11 is a first molded resin, and the molded resin 12 arranged on the bottom surface of the built-in substrate 11 is a second molded resin. Furthermore, the molded resin 12 that joins the first molded resins together is a third molded resin.

[0074] Fig. 4 is a diagram showing an example of the arrangement of board holes arranged in a built-in board included in the electric motor according to embodiment 1. Fig. 4 shows a top view of the built-in board 11 before the molding resin 12 is arranged. Here, a case where a surface-mounted IC 83 is arranged on the built-in board 11 will be described, but a chip resistor 84 may also be arranged on the built-in board 11. The surface-mounted IC 83 shown in Fig. 4 and Figs. 5 to 7 described below is an IC to which a QFP (Quad Flat Package) is applied.

[0075] A surface-mounted IC 83 is disposed on the upper surface of the built-in substrate 11. A plurality of pins 3 are disposed on the side surface of the surface-mounted IC 83. FIG. 4 shows a case in which a plurality of pins 3 are disposed on a side surface portion of the surface-mounted IC 83 that extends in a vertical direction (first direction). The first direction is a direction parallel to the side surface of the surface-mounted IC 83, and the surface-mounted IC 83 has a plurality of pins 3 arranged in the first direction. Note that a side surface portion of the surface-mounted IC 83 that extends in a horizontal direction may be defined as a second direction, and a plurality of pins 3 may be disposed on the side surface portions that extend in the first direction and the second direction.

[0076] In the upper surface area of ​​the built-in substrate 11, board holes 86 are arranged in an area other than the area where the surface-mounted ICs 83 are arranged (hereinafter, sometimes referred to as the IC arrangement area). The IC arrangement area includes an area where the surface-mounted ICs 83 themselves are arranged, an area where the pins 3 included in the surface-mounted ICs 83 are arranged, and an area (footprint 4) for attaching the pins 3 to the built-in substrate 11 by soldering. In the built-in substrate 11, the pins 3 on the bottom side of the surface-mounted ICs 83 are electrically connected to the footprint 4 on the upper surface side of the built-in substrate 11 by soldering. Therefore, in the IC arrangement area, the area where the pins 3 are arranged and the footprint 4 are the electrical connection positions (connection areas) between the surface-mounted components and the built-in substrate 11. In the built-in substrate 11, for example, a plurality of board holes 86 are arranged around the IC arrangement area.

[0077] In the first embodiment, the board holes 86 may be arranged in any region other than the IC arrangement region. That is, the board holes 86 penetrating the built-in substrate 11 are provided in a region of the top surface region of the built-in substrate 11 other than the region where surface-mounted components are arranged and outside the electrical connection positions between the surface-mounted components and the built-in substrate 11. Therefore, even if the built-in substrate 11 is large, the heat shock resistance can be improved by arranging a large number of board holes 86. Furthermore, even if the built-in substrate 11 is large, the heat shock resistance can be improved by arranging the board holes 86 in the outer periphery of the built-in substrate 11.

[0078] As described above, chip resistors 84 may be mounted on the built-in substrate 11. Because the area where electrodes are arranged is small in the chip resistor 84, the electrodes are more likely to peel off than in electronic components such as chip capacitors. If a gap is created between the molded resin 12 and the part of the built-in substrate 11 around the chip resistor 84 due to thermal expansion and contraction caused by a heat shock, the molded resin 12 may get caught on the electrodes of the chip resistor 84, causing the electrodes to peel off and leaving the chip resistor 84 electrically open.

[0079] In embodiment 1, as in the case of the surface-mounted IC 83, by arranging a substrate hole 86 near the chip resistor 84, the molded resin 12 on both sides of the built-in substrate 11 is mechanically connected, thereby suppressing the force that causes the molded resin 12 to peel off from the built-in substrate 11.

[0080] In this way, by arranging the substrate hole 86 near the chip resistor 84, as in the case of the surface-mounted IC 83, the molded resin 12 on both sides of the built-in substrate 11 is mechanically connected, thereby suppressing the force that causes the molded resin 12 to peel off from the built-in substrate 11.

[0081] That is, the molded resin 12 on the top surface of the built-in substrate 11 and the molded resin 12 on the bottom surface are joined by the molded resin 12 embedded in the substrate hole 86, which can suppress the force that causes the molded resin 12 to peel off from the built-in substrate 11. As a result, in the electric motor 1, the heat shock resistance of the surface-mounted IC 83 is improved, and electrical open circuits due to electrode peeling of the chip resistor 84 can be suppressed.

[0082] An air conditioner equipped with the electric motor 1 uses, for example, a flammable refrigerant to reduce greenhouse gas emissions. In the electric motor 1, the entire built-in substrate 11 is molded, so sparks and the like are not generated. Therefore, even if the flammable refrigerant leaks, the flammable refrigerant will not ignite. Even if a spark does occur, the board pressing hole 51 is located in a location on the built-in substrate 11 where there are no patterns, so the pattern on the built-in substrate 11, which is the live part of the built-in substrate 11, does not come into contact with the flammable refrigerant, and therefore ignition will not occur.

[0083] An air conditioner equipped with motor 1 uses a flammable refrigerant, such as R290 (propane refrigerant). This allows the air conditioner to use a higher condensation temperature than conventional refrigerants such as R32 (hydrofluorocarbon: HFC), thereby enabling more efficient operation. As the condensation temperature rises, the temperature of the heat exchanger rises. The air passing through the heat exchanger strikes the blower motor, raising the temperature of motor 1. This increases the temperature change of motor 1, requiring even higher heat shock resistance. In the first embodiment, molded resin 12 embedded in substrate hole 86 enhances heat shock resistance, thereby suppressing the force that would cause molded resin 12 to peel off from built-in substrate 11, even when R290 refrigerant is used.

[0084] The total area of ​​the board holes 86 provided in the built-in substrate 11 may be determined based on the area of ​​the IC placement area, or may be determined based on the area of ​​the area other than the IC placement area. Furthermore, the number of board holes 86 provided in the built-in substrate 11 or the area of ​​each board hole 86 may be determined based on the area of ​​the IC placement area, or may be determined based on the area of ​​the area of ​​the top surface of the built-in substrate 11 other than the IC placement area.

[0085] Here, the configuration of the chip resistor 84 will be described. Fig. 5 is a diagram schematically showing an example of the structure of a chip resistor mounted on the built-in substrate of the electric motor according to embodiment 1. Fig. 5 shows a cross-sectional view of the chip resistor 84.

[0086] 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 chip resistor electrodes 843 provided at both ends of the longitudinal direction, which is the extension direction of the ceramic substrate 841.

[0087] The chip resistor electrode 843 contacts an end of the resistor 842 provided on the upper surface of the ceramic substrate 841 at an end in the longitudinal direction of the ceramic substrate 841, and is disposed in close contact with the surface of the ceramic substrate 841 up to a predetermined position on the bottom surface of the ceramic substrate 841. That is, the chip resistor electrode 843 is provided so as to cover the side surface of the end in the longitudinal direction of the ceramic substrate 841, part of the upper surface, and part of the bottom surface in a C-shape and an inverted C-shape when viewed from the cross-sectional direction shown in FIG.

[0088] In the built-in substrate 11, a chip resistor electrode 843 on the bottom side of the chip resistor 84 is electrically connected to the top surface of the built-in substrate 11. Therefore, when the surface-mounted component is a chip resistor 84, the region of the IC placement region where the chip resistor electrode 843 is arranged on the bottom side of the chip resistor 84 is the electrical connection position (connection region) between the surface-mounted component and the built-in substrate 11.

[0089] The chip resistor 84 has chip resistor electrodes 843 on the side surfaces at both longitudinal ends, and no electrodes are provided on the side surfaces along the longitudinal direction. That is, the electrodes of the chip resistor 84 are not provided on the side surfaces in the longitudinal direction, which is the extension direction of the chip resistor 84, but on the side surfaces in the lateral direction. Therefore, compared to passive elements such as chip capacitors, which have electrodes provided on the side surfaces along the longitudinal direction, the chip resistor electrodes 843 of the chip resistor 84 are more likely to peel off.

[0090] 6 is a diagram showing an example of the state of the chip resistor when a gap occurs between the built-in substrate and the mold resin, and shows an enlarged view of the area A in FIG. 5 when no substrate hole 86 is provided.

[0091] As shown in FIG. 6 , a gap 845 may be formed between the resistor 842 and the chip resistor electrode 843 on the top surface of the chip resistor 84. When an embedded substrate 11 on which such a chip resistor 84 is mounted is insert-molded, the molded resin 12 may enter the gap 845. In such a case, the molded resin 12 that has entered the gap 845 between the resistor 842 and the chip resistor electrode 843 of the chip resistor 84 is lifted up due to thermal expansion and contraction caused by a heat shock. That is, the molded resin 12 is peeled off from the embedded substrate 11 and lifted up. As a result, the molded resin 12 that has entered the gap 845 becomes caught on the chip resistor electrode 843, and the chip resistor electrode 843 is lifted up together with the molded resin 12. This may cause the chip resistor electrode 843 to peel off from the resistor 842, resulting in an electrical open circuit of the resistor.

[0092] In this way, if board holes 86 were not provided, the electrical connection between built-in substrate 11 and chip resistors 84 would be easily severed. On the other hand, in embodiment 1, board holes 86 are provided in built-in substrate 11, so molded resin 12 is less likely to peel off from built-in substrate 11. As a result, surface-mounted ICs 83 and chip resistors 84 are less likely to be pulled by molded resin 12, and the electrical connection between built-in substrate 11 and surface-mounted components (surface-mounted ICs 83 and chip resistors 84) is less likely to be severed.

[0093] Furthermore, as the size of the chip resistor 84 becomes smaller, the chip resistor electrodes 843 tend to peel off, particularly in chip resistors 84 that are equal to or 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, when a chip resistor 84 of 1005 size or smaller is mounted on the built-in substrate 11, it is desirable to arrange substrate holes 86 around the chip resistor 84. Of course, substrate holes 86 may also be arranged around chip resistors 84 that are larger than the 1005 size.

[0094] Fig. 7 is a diagram showing an example of the configuration of an internal substrate and molded resin included in an electric motor of a comparative example. Fig. 7 shows a cross-sectional view of an internal substrate 11X and molded resin 12X included in the electric motor of the comparative example. Of the components in Fig. 7, components that achieve the same function as those in the internal substrate 11 of the first embodiment shown in Fig. 3 are given the same reference numerals, and duplicated explanations will be omitted. At least one of a surface-mounted IC 83 and a chip resistor 84 is disposed on the internal substrate 11X.

[0095] The built-in substrate 11 has a substrate hole 86, but the built-in substrate 11X does not have a substrate hole 86. Therefore, a gap 850 is formed between the molded resin 12X and the built-in substrate 11X due to thermal expansion and thermal contraction caused by a heat shock, making the molded resin 12X more likely to peel off from the built-in substrate 11X. As a result, the surface-mounted IC 83 and the chip resistor 84 are pulled by the molded resin 12X and more likely to peel off from the built-in substrate 11X.

[0096] If the surface-mounted component mounted on the built-in substrate 11X is a surface-mounted IC 83, a solder crack will occur in the solder connecting the surface-mounted IC 83 to the built-in substrate 11X, and the electrical connection between the built-in substrate 11X and the surface-mounted IC 83 will be severed.

[0097] Furthermore, if the surface-mounted component mounted on the built-in substrate 11X is a chip resistor 84, the chip resistor electrode 843 peels off from the resistor 842, and the electrical connection between the built-in substrate 11X and the chip resistor 84 is cut off.

[0098] As described above, in the electric motor 1 of the first embodiment, a board hole 86 penetrating the built-in board 11 is arranged in a region of the top surface of the built-in board 11 other than the region where the surface-mounted components are arranged and outside the positions of electrical connection between the surface-mounted components and the built-in board 11. The board hole 86 is filled with a molded resin 12 (third molded resin) that bonds the molded resin 12 (first molded resin) arranged on the top surface of the built-in board 11 to the molded resin 12 (second molded resin) arranged on the bottom surface of the built-in board 11. This bonds the molded resins 12 arranged on the top and bottom surfaces of the built-in board 11 in a region outside the positions of electrical connection between the surface-mounted components and the built-in board 11, making the molded resin 12 less likely to peel off the built-in board 11 and suppressing the force that would cause the molded resin 12 to peel off the surface-mounted components (such as the surface-mounted IC 83 and the chip resistor 84) mounted on the built-in board 11. Therefore, regardless of the size of the built-in substrate 11 disposed in the electric motor 1, it is possible to prevent the electrical connection between the built-in substrate 11 and the surface-mounted components mounted on the built-in substrate 11 from being cut off.

[0099] Furthermore, in the case of a surface-mounted IC 83, the motor 1 may not meet the standards for the heat shock test, but in embodiment 1, the board hole 86 is provided, which improves the heat shock resistance and allows the motor 1 to meet the standards for the heat shock test.

[0100] Second Embodiment Next, a second embodiment will be described with reference to Fig. 8. In the second embodiment, board holes (board holes 86A, which will be described later) are arranged between the pins 3 in the upper surface area of ​​the built-in board 11.

[0101] Fig. 8 is a diagram showing an example of the arrangement of board holes arranged in a built-in board provided in an electric motor according to embodiment 2. Of the components in Fig. 8, those that achieve the same functions as those in the built-in board 11 of embodiment 1 shown in Fig. 4 are assigned the same reference numerals, and duplicated explanations will be omitted.

[0102] Fig. 8 shows a top view of the built-in substrate 11 before the molding resin 12 is arranged. Here, a case where a surface-mounted IC 83 is arranged on the built-in substrate 11 will be described. Note that although Fig. 8 and Figs. 9 to 11, which will be described later, show portions hatched, Figs. 8 to 11 are top views of the built-in substrate 11.

[0103] Among the high-voltage compatible surface-mount ICs 83, there are ICs in which the distance between the pins 3 of the surface-mount IC 83 is wider than a specific value (for example, 1 mm). The wider the distance between the pins, the smaller the ratio of the area fixed to the built-in substrate 11 by solder relative to the body size of the surface-mount IC 83, and therefore the lower the heat shock resistance.

[0104] For this reason, pins 3 with a pin spacing greater than a specific value are prone to solder cracks, particularly after heat shock testing, and often become electrically open. Therefore, in the second embodiment, board holes 86A are placed in the locations between pins with a pin spacing greater than a specific value, and molded resin 12 is filled into these board holes 86A. In this way, in the second embodiment, board holes 86A can be placed in close proximity to pins 3 with weak heat shock resistance, thereby significantly improving heat shock resistance. Board holes 86A are first board holes. In other words, in the second embodiment, the board holes include board hole 86 and board hole 86A, which is the first board hole.

[0105] In the upper surface region of the built-in substrate 11, the substrate holes 86 are arranged in a region other than the IC arrangement region where the surface-mounted ICs 83 are arranged. In the second embodiment, in the upper surface region of the built-in substrate 11, the substrate holes 86A are arranged between adjacent pins 3 (between the pins).

[0106] The board holes 86A may have a different shape or size than the board holes 86 described in the first embodiment, or may have the same shape or size. Furthermore, the board holes 86A disposed in the built-in board 11 may have a size and shape that correspond to the spacing between the pins. That is, the size and shape of the board holes 86A may be determined for each spacing and shape of the pins. When the board holes 86A are disposed between the pins, it is not necessary to dispose the board holes 86A near the board holes 86A.

[0107] 8 shows a case where board hole 86A is arranged in the area between pins 3 arranged on the right side surface of surface-mounted IC 83. Note that, like board hole 86, board hole 86A is not arranged in the area of ​​footprint 4.

[0108] As described above, in the second embodiment, the built-in substrate 11 is formed with the substrate hole 86 and the substrate hole 86A located in the inter-pin region. Then, the molded resin 12 is poured into the built-in substrate 11 on which the surface-mounted IC 83 is located, thereby filling the substrate holes 86 and 86A with the molded resin 12. By filling the substrate holes 86 and 86A with the molded resin 12 in this manner, the molded resin 12 on both sides of the built-in substrate 11 is mechanically connected by the molded resin 12 in the substrate holes 86 and 86A.

[0109] Pins with wide spacing have weak heat shock resistance, but in embodiment 2, board holes 86A are arranged between the pins, so that board holes 86A can be arranged near surface-mounted IC 83, thereby improving heat shock resistance.

[0110] The total area of ​​the board holes 86, 86A provided in the built-in substrate 11 may be determined based on the area of ​​the IC placement area, or may be determined based on the area of ​​the area other than the IC placement area. Furthermore, the number of board holes 86, 86A provided in the built-in substrate 11 or the area of ​​each board hole 86, 86A may be determined based on the area of ​​the IC placement area, or may be determined based on the area of ​​the area of ​​the top surface of the built-in substrate 11 other than the IC placement area.

[0111] In this way, in embodiment 2, substrate holes 86A are provided between the pins, and molded resin 12 embedded in substrate holes 86A joins molded resin 12 provided on the top surface of built-in substrate 11 to molded resin 12 provided on the bottom surface of built-in substrate 11.

[0112] As a result, even if the pins are spaced apart widely, solder cracks can be prevented by the molding resin 12 in the board holes 86A arranged between the pins, and a decrease in heat shock resistance can be suppressed.

[0113] Third Embodiment Next, a third embodiment will be described with reference to Fig. 9. In the third embodiment, some of the board holes (board holes 86B, described later) arranged in the built-in board 11 are also used as copper-plated through holes.

[0114] Fig. 9 is a diagram showing an example of the arrangement of board holes arranged in a built-in board provided in an electric motor according to embodiment 3. Of the components in Fig. 9, those that achieve the same functions as those in the built-in board 11 of embodiment 1 shown in Fig. 4 are assigned the same reference numerals, and redundant explanations will be omitted.

[0115] 9 shows a top view of the built-in substrate 11 before the molding resin 12 is placed thereon. Here, a case where a surface-mounted IC 83 is placed on the built-in substrate 11 will be described, but a chip resistor 84 may also be placed on the built-in substrate 11.

[0116] Of the upper surface region of the built-in substrate 11, board holes 86 are arranged in a region other than the IC arrangement region where the surface-mounted IC 83 is arranged. Furthermore, in the third embodiment, board holes 86B are used as through holes in the upper surface region of the built-in substrate 11 that are connected to the wiring pattern 5. That is, board holes 86B are used to join the molded resin 12 provided on the upper surface of the built-in substrate 11 with the molded resin 12 provided on the bottom surface of the built-in substrate 11, and are also used as through holes connected to the wiring pattern 5.

[0117] Because wiring patterns 5 are drawn from each pin 3 of surface-mounted IC 83 via footprint 4, if the hole is not a through-hole (a non-through-hole not having copper plating), it may be difficult to arrange board holes 86B near pins 3, and the heat shock resistance may only improve slightly. In embodiment 3, board holes 86B are through-holes, so board holes 86B can be arranged in close proximity to pins 3, greatly improving the heat shock resistance.

[0118] In particular, when the built-in substrate 11 is formed by a printing method, the non-through holes and the wiring pattern 5 must be spaced apart by a specific distance or more, so when the substrate holes 86B are through holes, the substrate holes 86B can be positioned closer to the surface-mounted ICs 83 than when the substrate holes 86B are non-through holes. Furthermore, since the substrate holes 86B also serve as through holes, wiring efficiency is improved.

[0119] In this manner, in the third embodiment, at least some of the board holes are through holes provided in the built-in board 11.

[0120] Note that substrate hole 86B may be a hole of a different shape or size from substrate hole 86 described in embodiment 1, or may be a hole of the same shape or size as substrate hole 86 described in embodiment 1. When substrate hole 86B is provided, substrate hole 86 does not need to be provided near substrate hole 86B.

[0121] The total area of ​​the board holes 86, 86B provided in the built-in substrate 11 may be determined based on the area of ​​the IC placement area, or may be determined based on the area of ​​the area other than the IC placement area. Furthermore, the number of board holes 86, 86B provided in the built-in substrate 11 or the area of ​​each board hole 86, 86B may be determined based on the area of ​​the IC placement area, or may be determined based on the area of ​​the area of ​​the top surface of the built-in substrate 11 other than the IC placement area.

[0122] In this way, in the third embodiment, the board hole 86B arranged in the built-in board 11 doubles as a through hole, so that the board hole 86B can be arranged near the surface-mounted IC 83, improving the heat shock resistance.

[0123] Fourth Embodiment Next, a fourth embodiment will be described with reference to Fig. 10. In the fourth embodiment, some of the board holes (board holes 86C, described later) arranged in the built-in board 11 are arranged near the end pins 3 of the surface-mounted IC 83.

[0124] Of the pins 3 of the surface-mounted IC 83, the pins 3 at the ends are more susceptible to stress due to heat shock than the pins 3 in the center, and are more likely to develop solder cracks. For this reason, in the fourth embodiment, some of the board holes are positioned near the pins 3 at the ends, thereby improving heat shock resistance.

[0125] Fig. 10 is a diagram showing a first example of the arrangement of board holes arranged on a built-in board included in an electric motor according to embodiment 4. Of the components in Fig. 10, those that achieve the same functions as those in the built-in board 11 of embodiment 1 shown in Fig. 4 are given the same reference numerals, and duplicated explanations will be omitted.

[0126] 10 shows a top view of the built-in substrate 11 before the molding resin 12 is placed thereon. Here, a case where a surface-mounted IC 83 is placed on the built-in substrate 11 will be described.

[0127] Of the upper surface area of ​​the built-in substrate 11, board holes 86 are arranged in an area other than the IC placement area where the surface-mounted IC 83 is arranged. In the built-in substrate 11 of Fig. 10, board holes 86C are arranged in the upper surface area of ​​the built-in substrate 11 near pins 3 arranged at the end (QFP end) of the surface-mounted IC 83. Fig. 10 shows a case where board holes 86C are arranged outside the four corners of the rectangular IC placement area.

[0128] Fig. 11 is a diagram showing a second example of the arrangement of board holes arranged in a built-in board provided in an electric motor according to embodiment 4. Of the components in Fig. 11, components that achieve the same functions as those in the built-in board 11 shown in Fig. 10 are given the same reference numerals, and duplicated explanations will be omitted. The surface-mounted IC 83 shown in Fig. 11 is an IC to which an SOP (Small Outline Package) is applied.

[0129] 11 shows a top view of the built-in substrate 11 before the molding resin 12 is placed thereon. Here, a case where a surface-mounted IC 83 is placed on the built-in substrate 11 will be described.

[0130] Of the upper surface area of ​​the built-in substrate 11, board holes 86 are arranged in an area other than the IC placement area where the surface-mounted IC 83 is arranged. In the built-in substrate 11 of Fig. 11, board holes 86C are arranged in the upper surface area of ​​the built-in substrate 11 near pins 3 arranged at the end (SOP end) of the surface-mounted IC 83. Fig. 11 shows a case where board holes 86C are arranged outside the four corners of the rectangular IC placement area.

[0131] In this way, board hole 86C is located closer to pin 3 located at the end in the first direction than to pin 3 located in the center in the first direction. In other words, the distance between pin 3 at the end and board hole 86C is shorter than the distance between pin 3 at the center and board hole 86C. Board hole 86C is a second board hole. That is, in embodiment 4, the board holes include board hole 86 and board hole 86C, which is the second board hole.

[0132] The pins 3 at the ends have weaker heat shock resistance, but in embodiment 4, the board holes 86C are located near the end pins 3, so the heat shock resistance of the end pins 3 can be improved.

[0133] Note that substrate hole 86C may be a hole of a different shape or size from substrate hole 86 described in embodiment 1, or may be a hole of the same shape or size as substrate hole 86 described in embodiment 1. When substrate hole 86C is provided, substrate hole 86 does not need to be provided near substrate hole 86C.

[0134] The total area of ​​the board holes 86, 86C provided in the built-in substrate 11 may be determined based on the area of ​​the IC placement area or the area of ​​the area other than the IC placement area. Furthermore, the number of board holes 86, 86C provided in the built-in substrate 11 or the area of ​​each board hole 86, 86C may be determined based on the area of ​​the IC placement area or the area of ​​the area of ​​the top surface of the built-in substrate 11 other than the IC placement area.

[0135] As described above, according to the fourth embodiment, since the board hole 86C is disposed in the vicinity of the end pin 3 among the pins 3, the heat shock resistance of the end pin 3 can be improved.

[0136] Fifth Embodiment Next, a fifth embodiment will be described with reference to Fig. 12. In the fifth embodiment, the electric motor 1 is applied to an air conditioner.

[0137] 12 is a diagram schematically illustrating an example of the configuration of an air conditioner according to embodiment 5. The air conditioner 200 includes an indoor unit 210 and an outdoor unit 220 connected to the indoor unit 210.

[0138] The indoor unit 210 has any one of the electric motors 1 described in the first to fourth embodiments, an indoor unit circuit board 211, and an indoor unit blower (not shown). The outdoor unit 220 has an outdoor unit blower 223.

[0139] The outdoor unit blower 223 and the indoor unit blower each incorporate, as a drive source, any of the electric motors 1 described in embodiments 1 to 4. In particular, when the air conditioner 200 is for commercial use, high output and high heat dissipation performance are required, and therefore, application of any of the electric motors 1 described in embodiments 1 to 4 will increase the heat dissipation effect.

[0140] In addition to the air conditioner 200, the electric motor 1 can also be mounted and used in ventilation fans, home appliances, machine tools, and the like.

[0141] Thus, according to the fifth embodiment, since any of the electric motors 1 described in the first to fourth embodiments is applied to the air conditioner 200, the temperature rise of the built-in substrate 11 can be significantly suppressed.

[0142] Furthermore, since the air conditioner 200 is equipped with any of the electric motors 1 described in embodiments 1 to 4, it is possible to prevent the electrical connection between the built-in board 11 and the surface-mounted components mounted on the built-in board 11 from being severed, regardless of the size of the built-in board 11 placed on the electric motor 1.

[0143] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0144] 1 electric motor, 3 pin, 4 footprint, 5 wiring pattern, 10 molded stator, 11, 11X built-in board, 12, 12X molded resin, 13 lead wire, 14 lead outlet portion, 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 portion, 33 output side bearing, 34 anti-output side bearing, 40 magnet, 41 connection point, 50 magnetic sensor, 51 board pressing hole, 60 bracket, 61 press-fit portion, 70 control portion, 75 overcurrent detection resistor, 77 high-voltage power supply, 78 low-voltage power supply, 79A to 79C ground, 80 power IC, 81, 81A to 81F power transistor, 82 Gate drive circuit, 83 surface-mounted IC, 84 chip resistor, 85 protection circuit, 86, 86A to 86C board holes, 200 air conditioner, 210 indoor unit, 211 indoor unit board, 220 outdoor unit, 223 outdoor unit blower, 841 ceramic board, 842 resistor, 843 chip resistor electrode, 845, 850 gap, A area.

Claims

1. An electric motor comprising: a rotor; a stator provided on the outer periphery of the rotor; a built-in board that controls the drive of the rotor and on which surface-mounted components which are electronic components are mounted; and a molded resin that covers the entire built-in board and is integrally molded with the built-in board, wherein a board hole that penetrates the built-in board is arranged in an area of ​​the top surface of the built-in board other than the area where the surface-mounted components are arranged and outside the positions of electrical connection between the surface-mounted components and the built-in board, and a third molded resin that joins a first molded resin arranged on the top surface of the built-in board and a second molded resin arranged on a bottom surface of the built-in board is filled in the board hole.

2. The electric motor according to claim 1, wherein the surface mount component is a surface mount integrated circuit having a plurality of pins, and the board holes include a first board hole arranged at a location where the interval between adjacent pins is 1 mm or more.

3. The electric motor according to claim 1, wherein the surface mount component is a chip resistor having electrodes on both longitudinal ends.

4. The electric motor according to claim 1, wherein the surface mount component is a surface mount integrated circuit having a plurality of pins arranged in a first direction parallel to a side surface of the surface mount component, and the board hole includes a second board hole that is arranged closer to a pin that is arranged at an end of the first direction than to a pin that is arranged in the center of the first direction.

5. The cross-sectional area of ​​the board hole when cut by a plane parallel to the top surface of the surface-mounted component is 0.5 mm 2 The electric motor according to any one of claims 1 to 4, wherein:

6. The electric motor according to any one of claims 1 to 5, wherein at least some of the board holes are through holes provided in the built-in board.

7. An air conditioner comprising an electric motor according to any one of claims 1 to 6.

8. The air conditioner according to claim 7, which performs air conditioning using a flammable refrigerant.

9. The air conditioner according to claim 8, wherein the flammable refrigerant is propane refrigerant.

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