electronic machines

Abstract

To provide an electronic device that can measure the temperature of an appropriate location on a circuit board using a temperature sensor. [Solution] On the mounting surface 50a of the capacitor substrate 50, the shortest point 57 is defined as a location located between the first through-hole K1 and the adjacent through-hole K3 aligned in the second direction Y, and where the distance between the first through-hole K1 and the adjacent through-hole K3 aligned in the second direction Y is the shortest. The temperature sensor 74 measures the temperature on the mounting surface 50a at a location downstream of the shortest point 57 in the first current direction X1 on the nearest conductive layer 55.

Description

Technical Field

[0001] The present invention relates to an electronic device.

Background Art

[0002] An inverter, which is an example of an electronic device, has a semiconductor substrate on which semiconductor elements are mounted, a capacitor substrate on which capacitors are mounted, and a control substrate on which a control circuit is mounted. Further, the inverter measures the temperature of each substrate with a temperature sensor. When the temperature measured by the temperature sensor reaches a preset temperature for each substrate, the driving of the motor is restricted for the protection of the electronic components mounted on each substrate. For example, Patent Document 1 discloses a technique in which a temperature sensor is provided near a motor driver on a substrate on which a motor driver for driving a motor is mounted, and the motor connected to the motor driver is controlled according to the output of this temperature sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As in Patent Document 1, it is known to measure the temperature of a substrate with a temperature sensor for the protection of electronic components mounted on the substrate. However, in the substrate, depending on the measurement location by the temperature sensor, the measured temperature may be far from the temperature required for the protection of the electronic components. Therefore, it is desirable to arrange the temperature sensor at an appropriate location on the substrate.

Means for Solving the Problems

[0005] The electronic device for solving the above problems is a substrate in which a positive conductive layer and a negative conductive layer are laminated in an insulating state, and the current in the positive conductive layer and the current in the negative conductive layer flow in opposite directions in a first direction perpendicular to the lamination direction of the positive conductive layer and the negative conductive layer, the substrate having a plurality of through holes formed therein in the lamination direction, a plurality of electronic components mounted on the mounting surface of the substrate, insert components inserted into each of the plurality of through holes, and a temperature sensor for measuring the temperature of the substrate, wherein the direction perpendicular to the lamination direction and the first direction is defined as the second direction, and the shortest point is defined as a location on the substrate that is located between the through holes aligned in the second direction and where the distance between the through holes aligned in the second direction is shortest, and the closest conductive layer among the positive conductive layer or the negative conductive layer is defined as the closest conductive layer, then the temperature sensor measures the temperature of the substrate at a position downstream of the shortest point in the direction of current flow in the closest conductive layer.

[0006] According to this, the shortest current flow point is where the current density is higher than at other points, and therefore the temperature at the shortest current flow point is higher than at other points. The temperature sensor measures the temperature of the substrate at a position downstream of the shortest current flow point in the direction of current flow in the nearest conductive layer. For example, compared to measuring the temperature at a point with a lower current density than the position downstream of the shortest current flow point in the direction of current flow in the nearest conductive layer, the temperature measured by the temperature sensor can be higher. Therefore, when limiting the operation of electronic components mounted on the substrate based on the temperature measured by the temperature sensor, the set temperature for that limit can be brought closer to the upper limit of the specified temperature of the electronic component. As a result, the degradation of the performance of the electronic device can be suppressed. In summary, electronic devices can measure the temperature at appropriate locations on the substrate using a temperature sensor.

[0007] With respect to the electronic device, the temperature sensor penetrates the mounting surface in the stacking direction and is inserted into the nearest conductive layer. If the shortest distance in the second direction is defined as the shortest distance, the temperature sensor may be positioned such that the distance between the temperature sensor and each of the two through holes that sandwich the shortest distance in the second direction is greater than half of the shortest distance.

[0008] According to this, the current that passes through the shortest point branches due to the presence of the temperature sensor and flows through the nearest conductive layer. Furthermore, if the temperature sensor is positioned so that the distance from each of the two through holes flanking the shortest point in the second direction is longer than half the shortest distance, then even if the branched current flows, the current density at the point where the branched current flows will not become greater than the current density at the shortest point. Therefore, the presence of the temperature sensor can suppress excessive temperature rise due to a large increase in current density, even if the current branches and flows.

[0009] With respect to the electronic device, if the through-hole located downstream in the direction of current flow in the nearest conductive layer from the two through-holes that sandwich the shortest point in the second direction is defined as the downstream through-hole, and if tangents are set between the downstream through-hole and each of the two through-holes that sandwich the shortest point in the second direction, and the point where the two tangents intersect is defined as the intersection, then the temperature sensor may be located downstream of the intersection in the direction of current flow in the nearest conductive layer, and in a region enclosed by the two tangents and the downstream through-hole.

[0010] According to this, in the nearest conductive layer, the current that passes through the shortest path flows outside the tangent of the downstream through-hole. Since the temperature sensor is positioned in the region, the temperature sensor does not obstruct the flow of current that flows outside the tangent.

[0011] In the case of electronic equipment, the substrate may be provided with a separating member that separates the temperature sensor from the mounting surface. According to this design, the temperature sensor is not inserted into the nearest conductive layer. Therefore, the obstruction of current flow that occurs when inserting the temperature sensor into the nearest conductive layer is eliminated. As a result, current concentration due to current obstruction is prevented, and the temperature rise of the substrate can be suppressed.

[0012] With respect to the electronic device, the temperature sensor may be bonded to the mounting surface of the substrate with an adhesive. According to this design, the temperature sensor is not inserted into the nearest conductive layer. This eliminates the obstruction of current flow that occurs when the temperature sensor is inserted into the nearest conductive layer. As a result, current concentration due to current obstruction is prevented, and the temperature rise of the substrate can be suppressed. [Effects of the Invention]

[0013] This invention allows for the measurement of the temperature at a suitable location on a substrate using a temperature sensor. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is an exploded perspective view showing the inverter. [Figure 2] Figure 2 is a plan view showing the inverter. [Figure 3] Figure 3 is a plan view showing the capacitor board. [Figure 4] Figure 4 is a cross-sectional view taken along line 4-4 in Figure 3. [Figure 5] Figure 5 is a partial plan view showing the temperature sensor on the capacitor board. [Figure 6] Figure 6 is a partial plan view illustrating the flow of current in adjacent conductive layers. [Figure 7] Figure 7 is a partial cross-sectional view showing another example of the arrangement of temperature sensors. [Figure 8] Figure 8 is a partial cross-sectional view showing another example of the arrangement of temperature sensors. [Modes for carrying out the invention]

[0015] Hereinafter, an embodiment in which the electronic device is embodied as an inverter will be described according to FIGS. 1 to 6. Note that the inverter of this embodiment is mounted on a forklift as a battery-powered industrial vehicle.

[0016] <Basic Configuration of Inverter> As shown in FIGS. 1 and 2, an inverter 10 as an electronic device includes a heat sink 11, a semiconductor substrate 20, a capacitor substrate 50, and a control substrate 60. A plurality of semiconductor elements 24 are mounted on the semiconductor substrate 20, and two input terminals 25, three output terminals 35, and two internal terminals 40 are also mounted. A plurality of capacitors 54 are mounted on the capacitor substrate 50. A control circuit (not shown) is mounted on the control substrate 60.

[0017] <Heat Sink> The heat sink 11 is made of a metal such as an aluminum-based metal or copper. The heat sink 11 has a rectangular plate-shaped fixing portion 12 and a number of fins 13 protruding from the fixing portion 12. The fins 13 protrude from one surface of the fixing portion 12 in the plate thickness direction, and the semiconductor substrate 20 is fixed to the other surface of the fixing portion 12 in the plate thickness direction. The semiconductor element 24 dissipates heat to the heat sink 11.

[0018] <Semiconductor Substrate and Semiconductor Element> The semiconductor substrate 20 is rectangular plate-shaped. The semiconductor substrate 20 is fixed to the fixing portion 12 by aligning the longitudinal direction of the semiconductor substrate 20 with the longitudinal direction of the fixing portion 12 and aligning the short-side direction of the semiconductor substrate 20 with the short-side direction of the fixing portion 12.

[0019] The semiconductor element 24 is a MOSFET. Note that the semiconductor element 24 may be a semiconductor element other than a MOSFET. For example, an insulated gate bipolar transistor may be adopted for the semiconductor element 24. The plurality of semiconductor elements 24 are mounted in a row in the short-side direction of the semiconductor substrate 20, and a plurality of rows of the semiconductor substrate 20 are provided at intervals in the longitudinal direction of the semiconductor substrate 20.

[0020] Multiple fixing holes (not shown) are formed in the semiconductor substrate 20. Each fixing hole penetrates the semiconductor substrate 20 in the thickness direction. The number of fixing holes formed in the semiconductor substrate 20 is the same as the screw through holes H1 formed in the capacitor substrate 50, which will be described later.

[0021] <Input terminals, output terminals, and internal terminals> Each of the input terminals 25, output terminals 35, and internal terminals 40 is made of a metal such as aluminum or copper. The two input terminals 25, the three output terminals 35, and the two internal terminals 40 are spaced apart from each other in the longitudinal direction of the semiconductor substrate 20.

[0022] The input terminal 25 has a base portion 26, a columnar portion 27 protruding from the base portion 26, and a base portion 28 protruding from the circumferential surface of the columnar portion 27. The base portion 26 of the input terminal 25 is fixed to the semiconductor substrate 20. The output terminal 35 has a base portion 36 and a columnar portion 37 protruding from the base portion 36. The base portion 36 of the output terminal 35 is fixed to the semiconductor substrate 20. The internal terminal 40 has a base portion 45 extending in the short direction of the semiconductor substrate 20 and a contact portion 43 protruding from the base portion 45. The base portion 45 of the internal terminal 40 is fixed to the semiconductor substrate 20.

[0023] The two input terminals 25 are located at both ends of the semiconductor substrate 20 in the longitudinal direction. The three output terminals 35 are positioned between the two input terminals 25 in the longitudinal direction of the semiconductor substrate 20, and are also spaced apart from each other in the longitudinal direction of the semiconductor substrate 20. The two internal terminals 40 are positioned between adjacent output terminals 35 in the longitudinal direction of the semiconductor substrate 20. Rows of semiconductor elements 24 are positioned between adjacent input terminals 25 and output terminals 35, and between output terminals 35 and internal terminals 40, respectively, in the longitudinal direction of the semiconductor substrate 20.

[0024] <Capacitor board and capacitors> The capacitor substrate 50, as a substrate, is positioned at a distance from the semiconductor substrate 20 in the thickness direction of the semiconductor substrate 20. The capacitor substrate 50 is rectangular in shape. The capacitor substrate 50 is fixed to the fixing part 12 with its longitudinal direction aligned with the longitudinal direction of the fixing part 12 and the semiconductor substrate 20, and its short direction aligned with the short direction of the fixing part 12 and the semiconductor substrate 20. In the following description, the longitudinal direction of the capacitor substrate 50 will be referred to as the first direction X, and the short direction of the capacitor substrate 50 will be referred to as the second direction Y. The first direction X is the direction in which current flows along the capacitor substrate 50. Therefore, the first direction X is set appropriately according to the direction in which current flows in the capacitor substrate 50. Thus, depending on the direction in which current flows in the capacitor substrate 50, the first direction X may also be set to the short direction of the capacitor substrate 50. The orientation of the second direction Y is also set appropriately according to the first direction X.

[0025] The capacitor substrate 50 has a mounting surface 50a and a support surface 50b that are opposite to each other in the thickness direction. The capacitors 54 as electronic components are mounted on the mounting surface 50a. Therefore, the inverter 10 has a plurality of capacitors 54 mounted on the mounting surface 50a of the capacitor substrate 50. The capacitors 54 are, for example, cylindrical. The capacitors 54 are mounted on the mounting surface 50a such that the axial direction of the capacitors 54 coincides with the thickness direction of the capacitor substrate 50.

[0026] Multiple capacitors 54 form a row extending in the first direction X of the capacitor substrate 50. Two rows of capacitors 54 are formed spaced apart in the second direction Y of the capacitor substrate 50. In each row of capacitors 54, multiple capacitors 54 are in close contact with the second direction Y of the capacitor substrate 50.

[0027] As shown in Figure 3, the capacitor substrate 50 has two recesses 52, three output terminal through holes 53, and fourteen screw through holes H1. Each of the recesses 52, output terminal through holes 53, and screw through holes H1 penetrates the capacitor substrate 50 in the thickness direction of the substrate. The two recesses 52 are formed at both ends of the capacitor substrate 50 in the first direction X.

[0028] The three output terminal through-holes 53 are formed between one recess 52 and the other recess 52 in the first direction X of the capacitor substrate 50. The fourteen screw through-holes H1 are formed in the second direction Y, sandwiched between rows of two capacitors 54. In each row of screw through-holes H1, there is a mixture of screw through-holes H1 that sandwich each output terminal through-hole 53 in the second direction Y and screw through-holes H1 that are located closer to the center in the second direction Y than the screw through-hole H1.

[0029] As shown in Figure 4, the capacitor substrate 50 has three positive conductive layers 501, three negative conductive layers 502, and a plurality of insulating layers 503 that insulate the positive conductive layers 501 and the negative conductive layers 502. The capacitor substrate 50 is formed by stacking the positive conductive layers 501, the negative conductive layers 502, and the insulating layers 503 in the stacking direction Z. The positive conductive layers 501 and the negative conductive layers 502 are adjacent to each other with the insulating layers 503 in between. Therefore, in the capacitor substrate 50, the positive conductive layers 501 and the negative conductive layers 502 are stacked in an insulating state.

[0030] Each of the positive conductive layer 501 and the negative conductive layer 502 is formed from a metal foil, such as copper foil. A positive current flows through the positive conductive layer 501 in the first direction X of the capacitor substrate 50, and a negative current flows through the negative conductive layer 502 in the same direction. Therefore, the direction of the positive current flowing through the positive conductive layer 501 is one of the two directions of the first direction X and is perpendicular to the stacking direction Z. The direction of the negative current flowing through the negative conductive layer 502 is the other of the two directions of the first direction X and is perpendicular to the stacking direction Z.

[0031] The direction of the current flowing through the positive conductive layer 501 and the direction of the current flowing through the negative conductive layer 502 are opposite, but both flow in the first direction X. The direction of current flow in the positive conductive layer 501 is defined as the first current direction X1, and the direction of current flow in the negative conductive layer 502 is defined as the second current direction X2. Therefore, in the capacitor substrate 50, the current in the positive conductive layer 501 and the current in the negative conductive layer 502 flow in opposite directions in the first direction X, which is perpendicular to the stacking direction Z of the positive conductive layer 501 and the negative conductive layer 502. In the capacitor substrate 50, the direction perpendicular to the stacking direction Z and the first direction X is the second direction Y.

[0032] The insulating layer 503 is interposed between the positive conductive layer 501 and the negative conductive layer 502, covers the surface of the negative conductive layer 502 located at the first end in the stacking direction Z, and covers the surface of the positive conductive layer 501 located at the second end in the stacking direction Z.

[0033] In the capacitor substrate 50, the negative conductive layer 502 located at the first end in the stacking direction Z is designated as the nearest conductive layer 55. The mounting surface 50a of the capacitor substrate 50 is formed by the insulating layer 503 covering this nearest conductive layer 55. Therefore, the nearest conductive layer 55 is the negative conductive layer 502 that is closest to the mounting surface 50a in the stacking direction Z, out of the positive conductive layer 501 and the negative conductive layer 502.

[0034] The support surface 50b is formed by an insulating layer 503 that covers the positive conductive layer 501 located at the second end in the stacking direction Z. In addition, in the capacitor substrate 50, the positive conductive layer 501 adjacent to the nearest conductive layer 55 in the stacking direction Z is designated as the adjacent conductive layer 56.

[0035] Each of the recesses 52, output terminal through-holes 53, and screw through-holes H1 penetrates each positive conductive layer 501, each negative conductive layer 502, and each insulating layer 503 in the stacking direction Z. Therefore, the capacitor substrate 50 has multiple through-holes that penetrate in the stacking direction Z of the capacitor substrate 50.

[0036] <Control board> As shown in Figure 1, three holes 61 are formed in the control board 60. The holes 61 penetrate the control board 60 in the thickness direction. Electronic components (not shown) are mounted on the control board 60. These electronic components constitute a control circuit for controlling the semiconductor element 24.

[0037] <Overall view of the inverter> As shown in Figures 1 and 2, one of the two input terminals 25 is designated as the positive input terminal 251, and the other as the negative input terminal 252. The columnar portion 27 of the positive input terminal 251 is inserted into one recess 52 of the capacitor board 50, and the columnar portion 27 of the negative input terminal 252 is inserted into the other recess 52 of the capacitor board 50. A battery (not shown) is connected to the columnar portions 27 of the two input terminals 25. DC power is then input to the inverter 10 from the battery via the input terminals 25.

[0038] The columnar portions 37 of the three output terminals 35 are inserted into the output terminal through holes 53 of the capacitor board 50 and the holes 61 of the control board 60. Therefore, the output terminals 35 are insertable components inserted into the output terminal through holes 53 of the capacitor board 50.

[0039] A motor (not shown) is connected to the columnar portion 37 of the output terminal 35. One of the three output terminals 35 is electrically connected to the U phase of the motor, another is electrically connected to the V phase of the motor, and the remaining output terminal 35 is electrically connected to the W phase of the motor. Drive current is then output to the motor from each output terminal 35.

[0040] Each of the columnar portions 27 of the two input terminals 25 is in contact with the end face of the capacitor substrate 50 that defines the recess 52. The two input terminals 25 electrically connect the capacitor substrate 50 and the semiconductor substrate 20 by making contact with the capacitor substrate 50.

[0041] One of the two internal terminals 40 is designated as the positive internal terminal 401, and the other as the negative internal terminal 402. The positive internal terminal 401 and the negative internal terminal 402 are positioned to sandwich the middle output terminal 35 of the three output terminals 35 from both sides in the first direction X.

[0042] At the positive internal terminal 401 and the negative internal terminal 402, the base portion 45 is electrically connected to the semiconductor substrate 20, and the contact portion 43 is electrically connected to the capacitor substrate 50. The internal terminal 40 electrically connects the capacitor substrate 50 and the semiconductor substrate 20.

[0043] The negative internal terminal 402 is electrically connected to the negative conductive layer 502 of the capacitor substrate 50, and the positive internal terminal 401 is electrically connected to the positive conductive layer 501. Therefore, the current flowing through the negative conductive layer 502 flows in a first current direction X1 between the negative internal terminal 402 and the negative input terminal 252, and the current flowing through the positive conductive layer 501 flows in a second current direction X2 between the positive internal terminal 401 and the positive input terminal 251.

[0044] The inverter 10 comprises a plurality of screws S1 and an insulating collar C. The plurality of screws S1 are inserted together with the collar C through the screw through holes H1 of the capacitor board 50 and the fixing holes of the semiconductor board 20 via the input terminal 25, the output terminal 35, and the internal terminal 40, respectively. Therefore, the screws S1 are insertable components inserted into the screw through holes H1 of the capacitor board 50. In this way, the plurality of screws S1 fasten the capacitor board 50 and the semiconductor board 20 to the fixing portion 12 of the heat sink 11. The control board 60 is fastened to the input terminal 25 by screwing a screw member (not shown) inserted into a screw hole (not shown) of the control board 60 into the base portion 28 of the input terminal 25.

[0045] <Temperature sensor> A temperature sensor 74 is provided on the mounting surface 50a of the capacitor board 50. The temperature sensor 74 measures the temperature of the capacitor board 50. A control unit (not shown) monitors the capacitor board 50 based on the measurement value of the temperature sensor 74 and controls the motor output based on the measurement value of the temperature sensor 74. In detail, when the measurement value of the temperature sensor 74 reaches a specified temperature set lower than the upper limit of the rated temperature of the capacitor 54, the control unit reduces the motor output to protect the capacitor 54.

[0046] The lower the set specified temperature is compared to the upper limit of the rated temperature, the earlier the motor output reduction, aimed at protecting the capacitor 54, begins. An earlier start to motor output reduction is undesirable.

[0047] Furthermore, even under the same conditions, the temperature of the capacitor substrate 50 varies depending on the location on its mounting surface 50a. This is because the current density differs depending on the location on the mounting surface 50a of the capacitor substrate 50. The temperature of the capacitor substrate 50 increases as the density of the current flowing through the capacitor substrate 50 increases.

[0048] Therefore, if the temperature sensor 74 measures a location on the capacitor board 50 where the current density is low, the specified temperature set based on that temperature will also be lower. This will cause the motor output to start decreasing earlier in order to protect the capacitor 54. For this reason, it is preferable that the temperature sensor 74 be positioned on the capacitor board 50 so as to measure the temperature at a location that is hotter, i.e., a location where the current density is high.

[0049] On the other hand, if the placement of the temperature sensor 74 obstructs the flow of current on the capacitor board 50, the temperature of the capacitor board 50 will rise excessively, which is undesirable. Therefore, it is appropriate to place the temperature sensor 74 in a location on the capacitor board 50 that is hotter and does not obstruct the flow of current.

[0050] <Temperature sensor placement> As shown in Figure 4, the temperature sensor 74 penetrates the insulating layer 503 forming the mounting surface 50a and is inserted into the nearest conductive layer 55. Therefore, the temperature sensor 74 penetrates the mounting surface 50a in the stacking direction Z and is inserted into the nearest conductive layer 55. The temperature sensor 74 measures the temperature of the nearest conductive layer 55. Note that the temperature sensor 74 is not inserted into the adjacent conductive layer 56.

[0051] Figure 5 shows the capacitor board 50 from the mounting surface 50a, and schematically illustrates the temperature sensor 74. In the first direction X, the temperature sensor 74 is positioned between the middle output terminal through-hole 53 of the three output terminals 35 and the output terminal through-hole 53 downstream in the first current direction X1.

[0052] The distance in the second direction Y between adjacent output terminal through holes 53 and screw through holes H1 is defined as the first through-hole distance N1. The distance in the second direction Y between adjacent screw through holes H1 is defined as the second through-hole distance N2.

[0053] The capacitor board 50 has two patterns of adjacent through-holes in the second direction Y: output terminal through-holes 53 and screw through-holes H1, and screw through-holes H1 together. Therefore, there are two distances between adjacent through-holes in the second direction Y: the distance between first through-holes N1 and the distance between second through-holes N2. Thus, the distance between first through-holes N1, which is shorter than the distance between second through-holes N2, is the shortest distance on the capacitor board 50. On the capacitor board 50, the location between the output terminal through-holes 53 and screw through-holes H1 aligned in the second direction Y is the shortest location 57, where the distance between the through-holes aligned in the second direction Y is the shortest.

[0054] The output terminal through-hole 53 located upstream of the temperature sensor 74 in the first current direction X1 is designated as the first through-hole K1, and the screw through-hole H1 located downstream of the temperature sensor 74 is designated as the second through-hole K2, which is a downstream through-hole. This second through-hole K2 is a through-hole located downstream of the output terminal through-hole 53 and the screw through-hole H1 in the first current direction X1, with the shortest point 57 sandwiched between them in the second direction Y. The screw through-hole H1 that sandwiches the shortest point 57 together with the first through-hole K1 is designated as the adjacent through-hole K3. The distance N1 between the first through-holes is the distance in the second direction Y between the first through-hole K1 and the adjacent through-hole K3.

[0055] In the nearest conductive layer 55, current flows from the negative internal terminal 402 towards the negative input terminal 252. The current flowing through this nearest conductive layer 55 is affected by the presence of the output terminal through hole 53, the screw through hole H1, and the temperature sensor 74, which are located closer to the negative internal terminal 402 than to the negative input terminal 252.

[0056] Specifically, since current does not flow through the output terminal through holes 53 and screw through holes H1, the current flows between adjacent output terminal through holes 53 and screw through holes H1 in the second direction Y, and between adjacent screw through holes H1 in the second direction Y. Because the current concentrates at the shortest point 57, which is the shortest distance in the second direction Y, the current density at the shortest point 57 is higher than at other points. For this reason, the temperature at the shortest point 57 on the mounting surface 50a is the highest in the capacitor substrate 50.

[0057] As shown by arrow Q1 in Figure 5, the current that has passed through the shortest point 57 branches and flows around the second through-hole K2 downstream due to the presence of the second through-hole K2. Therefore, in the nearest conductive layer 55, the current density decreases along the first current direction X1 as you approach the second through-hole K2 from the shortest point 57. In the first current direction X1, the upstream position immediately next to the second through-hole K2 has a lower current density and a lower temperature compared to the shortest point 57.

[0058] As shown in Figures 2 and 6, in the adjacent conductive layer 56, current flows from the positive internal terminal 401 to the positive input terminal 251. In other words, in the adjacent conductive layer 56, current flows in the second current direction X2, as shown by arrow Q2 in Figure 6.

[0059] Around the temperature sensor 74, the current flowing through the adjacent conductive layer 56 in the second current direction X2 branches off from the second through-hole K2 and flows toward the first through-hole K1 and the adjacent through-hole K3 without being affected by the through-hole. Therefore, in the adjacent conductive layer 56, there is no change in current density between the first through-hole K1 and the second through-hole K2 in the second current direction X2, and the overall current density remains high.

[0060] As described above, in the capacitor substrate 50, in the first current direction X1, the temperature increases closer to the shortest point 57 due to the influence of the current density of both the nearest conductive layer 55 and the adjacent conductive layer 56, while the temperature decreases as you move downstream from the shortest point 57 due to the temperature decrease of the nearest conductive layer 55.

[0061] In the capacitor substrate 50, when the temperature sensor 74 is inserted into the conductive layer, the flow of current is obstructed by the temperature sensor 74. As a result, the temperature of the conductive phase becomes higher compared to the case where the temperature sensor 74 is not inserted. For this reason, even if the temperature sensor 74 is to be inserted into the conductive phase, it is preferable to insert it in a location with low current density. As described above, in the nearest conductive layer 55, the current density is low at the upstream position immediately adjacent to the second through-hole K2. For this reason, it is preferable to insert the temperature sensor 74 in the nearest conductive layer 55 immediately adjacent to the second through-hole K2 in the first current direction X1.

[0062] Therefore, the temperature sensor 74 is mounted on the mounting surface 50a in a location downstream of the shortest point 57 in the first current direction X1, and upstream of the second through-hole K2, which is a location with a low current density, so as to be inserted into the nearest conductive layer 55. The mounting position of this temperature sensor 74 is referred to as the mounting position 58.

[0063] As shown in Figure 5, the shortest distance between the temperature sensor 74 and the first through-hole K1 is defined as the first distance G1, and the shortest distance between the temperature sensor 74 and the adjacent through-hole K3 is defined as the second distance G2. The shortest distance between the first through-hole K1 and the adjacent through-hole K3 is defined as the distance between the first through-holes N1.

[0064] The first distance G1 and the second distance G2 are longer than half the distance N1 between the first through holes. Therefore, the temperature sensor 74 is positioned such that the following equations (1) and (2) hold true.

[0065] G1>1 / 2·N1…(1) G2 > 1 / 2 · N1 ... (2) Therefore, the mounting position 58 of the temperature sensor 74 is located at a distance greater than half the distance N1 between the first through holes, away from the first through hole K1 and the adjacent through hole K3.

[0066] Furthermore, it is preferable that the mounting position 58 of the temperature sensor 74 is located within the range of a circle CR with a radius of four times the distance N1 between the first through holes, centered on the central position OP in the second direction Y at the shortest point 57. In other words, the temperature sensor 74 can be placed anywhere downstream of the shortest point 57 in the first current direction X1.

[0067] Furthermore, the tangent line between the first through-hole K1 and the second through-hole K2 is defined as the first tangent line F1, and the tangent line between the second through-hole K2 and the adjacent through-hole K3 is defined as the second tangent line F2. In other words, tangent lines are set between the second through-hole K2 and the first through-hole K1 and the adjacent through-hole K3, which sandwich the shortest point 57 in the second direction Y. Note that the first tangent line F1 and the second tangent line F2 are set to intersect each other. The point where the first tangent line F1 and the second tangent line F2 intersect is defined as intersection T. On the mounting surface 50a, if the area downstream from intersection T in the first current direction X1 and enclosed by the first tangent line F1, the second tangent line F2 and the second through-hole K2 is defined as the arrangement area W shown by the dot hatching in Figure 5, then the mounting position 58 of the temperature sensor 74 is located in arrangement area W.

[0068] As described above, the mounting position 58 of the temperature sensor 74 is located within the range of a circle CR with a radius of four times the distance N1 between the first through holes, centered at the central position OP in the second direction Y at the shortest point 57. This position within circle CR is included in the placement area W. Therefore, it is more preferable that the temperature sensor 74 placed at mounting position 58 be located within circle CR within the placement area W.

[0069] [Effect of the Embodiment] Next, the operation of the embodiment will be described. The temperature of the capacitor substrate 50 on the mounting surface 50a is affected by the current density in the nearest conductive layer 55 and the adjacent conductive layer 56. The shortest point 57 has a higher current density than other points, and therefore the temperature at the shortest point 57 is higher than other points. The temperature sensor 74 measures the temperature of the capacitor substrate 50 at the mounting position 58 downstream from the shortest point 57 in the first current direction X1. Therefore, the temperature sensor 74 can measure the temperature of the high-temperature points on the capacitor substrate 50.

[0070] [Effects of the Embodiment] According to the above embodiment, the following effects can be obtained. (1) The temperature sensor 74 measures the temperature of the mounting position 58 on the capacitor board 50, which is downstream of the shortest point 57 in the first current direction X1. The shortest point 57 on the capacitor board 50 is hotter than other points on the capacitor board 50. For example, the temperature measured by the temperature sensor 74 can be higher than when measuring the temperature of a point with a lower current density than a point downstream of the shortest point 57 in the first current direction X1. Therefore, when a limit is imposed according to the temperature measured by the temperature sensor 74 in order to protect the capacitor 54 mounted on the capacitor board 50, the set temperature for imposing that limit can be brought closer to the upper limit of the standard temperature of the capacitor 54. As a result, the performance degradation of the inverter 10 can be suppressed. Thus, the inverter 10 can measure the temperature of an appropriate point on the capacitor board 50 using the temperature sensor 74.

[0071] (2) The current that passes through the shortest point 57 branches off due to the presence of the temperature sensor 74. The temperature sensor 74 is positioned such that the first distance G1 from the first through hole K1 and the second distance G2 from the adjacent through hole K3 are both longer than half the distance N1 between the first through holes. Therefore, even if the current that passes through the shortest point 57 branches off, the current density will not become greater than that of the shortest point 57. This prevents the temperature of the capacitor substrate 50 from rising excessively due to an increase in current density caused by the presence of the temperature sensor 74.

[0072] (3) In the nearest conductive layer 55, the current that passes through the shortest point 57 flows outside the first tangent F1 and the second tangent F2 of the second through hole K2. Since the temperature sensor 74 is placed in the placement region W between the first tangent F1 and the second tangent F2, the temperature sensor 74 does not obstruct the flow of current that flows outside the first tangent F1 and the second tangent F2. As a result, even with the temperature sensor 74 in place, it is possible to suppress an excessive rise in the temperature of the capacitor substrate 50.

[0073] (4) In the adjacent conductive layer 56, the current density is high throughout the second current direction X2 between the first through hole K1 and the second through hole K2. Therefore, if the temperature sensor 74 is inserted and installed in the adjacent conductive layer 56, it will obstruct the flow of current in the adjacent conductive layer 56 and cause a temperature rise. For this reason, the temperature sensor 74 is inserted only in the nearest conductive layer 55. Furthermore, the temperature sensor 74 is inserted in the nearest conductive layer 55 in a location with low current density. Thus, the temperature sensor 74 can measure the temperature of the capacitor substrate 50 near a location with high current density and in a location where it is not easy to obstruct the flow of current.

[0074] (5) The temperature sensor 74 is positioned within the range of a circle CR with a radius four times the distance N1 between the first through holes, centered at the central position OP in the second direction Y at the shortest point 57. Therefore, the temperature sensor 74 can be positioned not too far from the shortest point 57, which is a location on the capacitor substrate 50 where the current density is higher than at other locations. In other words, the temperature sensor 74 can suitably measure the temperature of the capacitor substrate 50 even downstream of the shortest point 57.

[0075] (6) The temperature sensor 74 is located in the placement area W. The placement area W is a location where current is less likely to flow after passing through the shortest point 57. Therefore, the temperature sensor 74 does not obstruct the flow of current in the nearest conductive layer 55.

[0076] [Example of changes] This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0077] ○As shown in Figure 7, the capacitor board 50 may have a separating member 70 that positions the temperature sensor 74 at a distance from the mounting surface 50a. The separating member 70 has a protruding portion 71 that projects in the thickness direction of the mounting surface 50a and a mounting portion 72 that bends relative to the protruding portion 71. The mounting portion 72 has a mounting surface 72a parallel to the mounting surface 50a. The temperature sensor 74 is mounted on the mounting surface 72a.

[0078] In this case, the mounting surface 72a faces a position downstream of the shortest point 57 on the mounting surface 50a in the first current direction X1. The temperature sensor 74 mounted on the mounting surface 72a is spaced apart from the mounting surface 50a in the stacking direction Z, but may be in contact with the mounting surface 50a. With this configuration, the obstruction of current flow caused by inserting the temperature sensor 74 into the nearest conductive layer 55 can be eliminated. As a result, current concentration due to current obstruction can be prevented, and the temperature rise of the capacitor substrate 50 can be suppressed.

[0079] In the configuration shown in Figure 7, the mounting surface 72a of the separating member 70 is preferably positioned facing the mounting position 58, but it may also be positioned upstream or downstream of the mounting position 58 in the first current direction X1. In this configuration, the temperature sensor 74 attached to the mounting surface 72a is positioned facing the mounting position 58, but may also be positioned upstream or downstream of the mounting position 58 in the first current direction X1.

[0080] As shown in Figure 8, the temperature sensor 74 may be bonded to the mounting surface 50a by adhesive 59. The temperature sensor 74 is bonded to the mounting surface 50a by adhesive 59 applied at a position downstream of the shortest point 57 on the mounting surface 50a in the first current direction X1. This eliminates the obstruction of current flow that occurs when inserting the temperature sensor 74 into the nearest conductive layer 55. As a result, current concentration due to current obstruction can be prevented, and the temperature rise of the capacitor substrate 50 can be suppressed.

[0081] In the configuration shown in Figure 8, the adhesive 59 is preferably applied to the mounting position 58, but it may also be applied upstream or downstream of the mounting position 58 in the first current direction X1. In this configuration, the temperature sensor 74, which is bonded to the mounting surface 50a by the adhesive 59, is positioned at the mounting position 58 via the adhesive 59, but it may also be positioned upstream or downstream of the mounting position 58 in the first current direction X1.

[0082] ○The temperature sensor 74 may be placed outside the placement area W, as long as it is downstream of the shortest point 57 in the first current direction X1. ○The temperature sensor 74 may be placed in a position that does not satisfy equations (1) and (2).

[0083] ○The temperature sensor 74 may be inserted into both the nearest conductive layer 55 and the adjacent conductive layer 56. ○The substrate on which the temperature sensor 74 is mounted may also be the control board 60. In this case, the hole 61 becomes a through hole, and the control circuit (not shown) becomes an electronic component. If through holes are formed for inserting screws to fix the control board 60 to the heat sink 11, the temperature sensor 74 measures the temperature at a location downstream from the shortest point in the first direction on the nearest conductive layer of the semiconductor substrate 20 where the control circuit is mounted.

[0084] ○The nearest conductive layer 55 may be a positive conductive layer 501, and the adjacent conductive layer 56 may be a negative conductive layer 502. ○The temperature sensor 74 may be positioned immediately downstream of the shortest point 57 in the first current direction X1. In this case, the temperature sensor 74 may be inserted only in the nearest conductive layer 55, or it may be inserted in both the nearest conductive layer 55 and the adjacent conductive layer 56. [Explanation of Symbols]

[0085] F1...First tangent, F2...Second tangent, H1...Screw through-hole as a through-hole, K1...First through-hole, K2...Second through-hole as a downstream through-hole, K3...Adjacent through-hole, N1...Distance between first through-holes as the shortest distance, S1...Screw as an inserted component, T...Intersection, W...Placement area, X...First direction, X1...First current direction, X2...Second current direction, Y...Second direction, Z...Layering direction, 10...Inverter as an electronic device, 35...Output terminal as an inserted component, 50...Capacitor substrate as a substrate, 50a...Mounting surface, 53...Output terminal through-hole as a through-hole, 54...Capacitor as an electronic component, 55...Closest conductive layer, 56...Adjacent conductive layer, 57...Shortest point, 59...Adhesive, 70...Separating member, 74...Temperature sensor, 501...Positive conductive layer, 502...Negative conductive layer.

Claims

1. A substrate in which a positive conductive layer and a negative conductive layer are laminated in an insulating state, and in which the current of the positive conductive layer and the current of the negative conductive layer flow in opposite directions in a first direction perpendicular to the lamination direction of the positive conductive layer and the negative conductive layer, wherein the substrate has a plurality of through holes formed therein that penetrate the substrate in the lamination direction, Multiple electronic components mounted on the mounting surface of the aforementioned substrate, Insertion components inserted into each of the multiple through holes, An electronic device having a temperature sensor for measuring the temperature of the substrate, The direction perpendicular to the stacking direction and the first direction is defined as the second direction. In the substrate, the shortest location is defined as a location located between the through holes arranged in the second direction, and where the distance between the through holes arranged in the second direction is the shortest. If, among the positive conductive layer or the negative conductive layer, the layer closest to the mounting surface in the stacking direction is defined as the closest conductive layer, The electronic device is characterized in that the temperature sensor measures the temperature of the substrate at a position downstream of the shortest point in the direction of current flow in the nearest conductive layer.

2. The temperature sensor penetrates the mounting surface in the stacking direction and is inserted into the nearest conductive layer. The electronic device according to claim 1, wherein, if the distance in the second direction at the shortest point is defined as the shortest distance, the temperature sensor is positioned such that the distance between each of the two through holes that sandwich the shortest point in the second direction and the temperature sensor is longer than half of the shortest distance.

3. If the through-hole located downstream in the direction of current flow in the nearest conductive layer from the two through-holes that sandwich the shortest point in the second direction is defined as the downstream through-hole, When tangents are set between the downstream through-hole and each of the two through-holes that sandwich the shortest point in the second direction, and the point where the two tangents intersect is defined as an intersection, The electronic device according to claim 2, characterized in that the temperature sensor is located downstream of the intersection in the direction of current flow in the nearest conductive layer, and in a region enclosed by the two tangents and the downstream through-hole.

4. The electronic device according to claim 1 or claim 2, wherein the substrate is provided with a separating member that separates the temperature sensor from the mounting surface.

5. The electronic device according to claim 1 or 2, wherein the temperature sensor is bonded to the mounting surface of the substrate with an adhesive.

Images