Electronic device and electronic device manufacturing method

Abstract

Provided is an electronic component in which a wider mounting region for the electronic component can be secured while securing the strength of a bus bar with respect to the stress of a screw. This electronic device comprises: a substrate on which the electronic component is mounted; and a bus bar that is disposed on the substrate, has a wider upper surface than a bottom surface that is in contact with the substrate, and is fixed to the substrate with a screw inserted into a stepwise through-hole. The screw head of the screw is fixed by the stepwise unevenness of the through-hole, the height of the electronic component is lower than the upper surface of the bus bar, and the electronic component is mounted so as to at least partially overlap with the upper surface of the bus bar.

Description

Electronic device and method of manufacturing electronic device

[0001] The present invention relates to an electronic device and a method for manufacturing an electronic device.

[0002] An inverter device has been proposed in which a plurality of capacitors are mounted in a row on the upper board of two vertically arranged boards, and a plurality of power elements are mounted in a row on the lower board (see Patent Document 1). In the inverter device described in Patent Document 1, a bus bar is disposed on the lower board, but when a bus bar is used in this manner, the board and the bus bar are fixed with screws to ensure electrical connection between the patterns on the board and the bus bar.

[0003] JP 2014-023181 A

[0004] One way to increase the packaging density of electronic components is to reduce the size of the bus bars that are screwed to the board, but reducing the size of the bus bars may reduce the bus bar's durability against the stress of the screws.

[0005] One aspect of the disclosed technique aims to provide a method for manufacturing an electronic component and an electronic device that can ensure a wider mounting area for electronic components while ensuring the strength of the bus bar against screw stress.

[0006] One aspect of the disclosed technology is exemplified by the following electronic device. The electronic device includes: a substrate on which electronic components are mounted; and a bus bar disposed on the substrate, the bus bar having a top surface wider than a bottom surface that contacts the substrate, and the bus bar fixed to the substrate with a screw inserted into a step-shaped through hole. The screw head is fixed at the step of the step-shaped through hole, the height of the electronic component is lower than the top surface of the bus bar, and at least a portion of the electronic component is mounted so as to overlap the top surface of the bus bar.

[0007] According to the disclosed technique, it is possible to provide an electronic component that can ensure a wider mounting area for the electronic component while ensuring the strength of the bus bar against the stress of the screws.

[0008] FIG. 1 is a perspective view illustrating an example of the appearance of an inverter device according to an embodiment. FIG. 2 is a diagram illustrating an inverter circuit of the inverter device according to an embodiment. FIG. 3 is a top view illustrating a state in which a control board is removed from the inverter circuit. FIG. 4 is a side view illustrating a state in which the control board is removed from the inverter circuit. FIG. 5 is a top view illustrating a state in which a control board and a capacitor board are removed from the inverter circuit. FIG. 6A is a first diagram illustrating an example of an input electrode bus bar. FIG. 6B is a second diagram illustrating an example of an input electrode bus bar. FIG. 7A is a third diagram illustrating an example of an input electrode bus bar. FIG. 7B is a fourth diagram illustrating an example of an input electrode bus bar. FIG. 8A is a first diagram illustrating an example of an arrangement of input electrodes in an inverter circuit. FIG. 8B is a second diagram illustrating an example of an arrangement of input electrodes in an inverter circuit. FIG. 9 is a diagram schematically illustrating the flow of current input from an input electrode. FIG. 10 is a diagram schematically illustrating the arrangement of extensions, output electrode bus bars, and power elements according to an embodiment. 11A and 11B are first and second diagrams illustrating variations in the shape of the extension portion as viewed in the Z direction.

[0009] Embodiments will now be described with reference to the drawings. FIG. 1 is a perspective view showing an example of the exterior of an inverter device 100 according to an embodiment. The inverter device 100 includes a housing 11, a heat sink 12, and a lid 13. The housing 11 is attached to the lid 13 by engaging claws 111, 112, and 113 formed on the housing 11 with claws 136, 137, and 138 formed on the lid 13. The heat sink 12 is disposed in thermal contact with the circuit boards housed within the housing 11 to dissipate heat generated by the circuit boards and various electronic components housed within the housing 11. Connection terminals 15 for connecting an external device such as a computer are provided on the outer surface of the housing 11. Note that in FIG. 1 , the direction from the heat sink 12 toward the lid 13 is the +Y direction, the direction from the input electrode 421 toward the input electrode 411 is the +X direction, and the direction perpendicular to the X and Y directions and from the output electrode 521 toward the breathing valve 14 is the +Z direction. The +Y direction is the upward direction, and the opposite direction is the downward direction.

[0010] The lid 13 has through holes 131, 132, 133, 134, and 135 formed therein, penetrating the thickness direction thereof. An input electrode 411 is provided in the through hole 131 so as to protrude from the lid 13. An input electrode 421 is provided in the through hole 132 so as to protrude from the lid 13. An input terminal 412 is provided in the input electrode 411, and an input terminal 422 is provided in the input electrode 421. The input terminals 412 and 422 are, for example, screw holes. For example, screw-shaped terminals of a power supply are fixed to the input terminals 412 and 422. An output electrode 511 is provided in the through hole 133 so as to protrude from the lid 13. An output electrode 521 is provided in the through hole 134 so as to protrude from the lid 13. An output electrode 531 is provided in the through hole 135 so as to protrude from the lid 13. The input terminals 412 and 422 are examples of "third screw holes."

[0011] The inverter device 100 converts DC power input via input electrodes 411 and 421 into three-phase AC power using an inverter circuit inside the inverter device 100 and outputs the converted three-phase AC power via output electrodes 511, 521, and 531. In the inverter device 100, for example, positive DC power is input to the input electrode 411, and negative DC power is input to the input electrode 421. That is, the positive terminal of a power supply is connected to the input electrode 411, and the negative terminal of the power supply is connected to the input electrode 421. In addition, in the inverter device 100, for example, U-phase AC power is output from the output electrode 511, V-phase AC power is output from the output electrode 521, and W-phase AC power is output from the output electrode 531. For example, when the inverter device 100 is connected to a motor, the output electrode 511 is connected to a U-phase terminal of the motor, the output electrode 521 is connected to a V-phase terminal of the motor, and the output electrode 531 is connected to a W-phase terminal of the motor. The direction of the current flowing through the input electrodes 411, 421 and the output electrodes 511, 521, 531 changes depending on the switching state of the power element 40 (see FIG. 5).

[0012] 2 is a diagram illustrating an inverter circuit 200 of the inverter device 100 according to the embodiment. In the inverter device 100, the inverter circuit 200 is housed in a main body formed by a housing 11, a heat sink 12, and a lid 13. The inverter circuit 200 includes a control board 2, a capacitor board 3, and a power board 4. The control board 2, the capacitor board 3, and the power board 4 are arranged in a line in the Y direction.

[0013] The control board 2 is a board on which a circuit is mounted that controls the conversion of DC power to AC power by the inverter device 100. The control board 2 is mounted with, for example, a circuit that turns on / off the power supply to the inverter device 100 and a circuit that controls the start and end of conversion of DC power input from the input electrodes 411 and 421 into AC power.

[0014] The capacitor substrate 3 is a substrate on which multiple capacitors 30 are arranged. FIG. 3 is a top view illustrating the inverter circuit 200 with the control substrate 2 removed. FIG. 4 is a side view illustrating the inverter circuit 200 with the control substrate 2 removed. The capacitor substrate 3 is formed, for example, in a substantially rectangular plate shape when viewed in the Y direction. Recesses 31, 32, 33, 34, 35, and 36 are formed at positions corresponding to the input electrodes 411 and 421 and the output electrodes 511, 521, and 531 of the capacitor substrate 3, respectively. The input electrodes 411 and 421 and the output electrodes 511, 521, and 531 protrude upward beyond the capacitor substrate 3 via the recesses 31, 32, 33, 34, 35, and 36. The capacitor substrate 3 is fixed to the input electrode bus bars 41 and 42 and the output electrode bus bars 51, 52, and 53 by, for example, screws 91. The capacitor substrate 3 is an example of an "upper substrate."

[0015] The power board 4 is a board on which a plurality of power elements 40 are arranged. FIG. 5 is a top view illustrating the inverter circuit 200 with the control board 2 and the capacitor board 3 removed. The power board 4 is formed, for example, in the shape of a substantially rectangular plate when viewed in the Y direction. The power board 4 is provided with input electrode bus bars 41, 42, output electrode bus bars 51, 52, 53, and a plurality of power elements 40. The power elements 40 include, for example, switching elements with diodes connected in parallel. The power elements 40 are an example of an "electronic component."

[0016] The input electrode bus bars 41, 42 are plate-shaped members that receive DC power input from the input electrodes 411, 421. The input electrode bus bars 41, 42 are formed of a conductor such as metal. The input electrode bus bars 41, 42 are fixed to the power board 4 with screws 92. FIGS. 6A and 6B are diagrams showing an example of the input electrode bus bar 41. FIG. 6A is a top view of the input electrode bus bar 41, and FIG. 6B is a side view of the input electrode bus bar 41. The input electrode bus bar 41 has extensions 413, 414 that are parallel to each other, and a connection portion 415 that connects the extensions 413 and 414. The extensions 413, 414 are members that extend in the Z direction. The connection portion 415 is a member that extends in the X direction. The connection portion 415 connects the +Z-direction end of the extension portion 413 and the +Z-direction end of the extension portion 414, and the input electrode bus bar 41 is formed in a U-shape in top view. The extension portions 413 and 414 are each formed with two screw holes 418, for example, aligned in the Z direction, into which screws 92 for fixing the input electrode bus bar 41 to the power board 4 are inserted. The extension portions 413 and 414 are also each formed with two screw holes 419, for example, aligned in the Z direction, into which screws 91 for fixing the capacitor board 3 to the power board 4 are inserted. The end of the input electrode 411 on the extension portion 413 side is formed with a reinforcing portion 417 for reinforcing the connection between the input electrode 411 and the extension portion 413. Because the input electrode bus bar 41 is formed of a conductor, power input via the input electrode 411 is supplied to the extension portions 413 and 414 and the connection portion 415. The screw 94 is an example of a "screw." The screw hole 418 is an example of a "screw hole." The screw hole 419 is an example of a "second screw hole."

[0017] The input electrode 411 is provided at the end of the extension portion 413 in the +Z direction so as to protrude upward. The connection portion 415 includes a thin portion 416A and a base portion 416B. The base portion 416B is disposed on the extension portion 413 side of the connection portion 415. The thin portion 416A is disposed on the extension portion 414 side of the connection portion 415. The thin portion 416A is formed to be thinner in the Y direction than the base portion 416B. As can be seen from FIG. 6B , the extension portions 413 and 414 are trapezoidal when viewed in the Z direction, with the width W1 of the upper base being larger than the width W2 of the lower base. The width W1 of the upper base is determined so that the distance between the screw hole 418 and the ends 413A and 414A of the extension portions 413 and 414 is a predetermined distance that ensures the rigidity of the input electrode bus bar 41. That is, the opening of the screw hole 418 on the surface (top surface) of the input electrode bus bar 41 opposite to the surface (bottom surface) facing the power board 4 is formed smaller than the width W1 of the upper base. Also, the opening of the screw hole 418 on the surface of the input electrode bus bar 41 facing the power board 4 is formed smaller than the width W2 of the lower base. As can be understood with reference to FIG. 5 , the connection portion 415 is arranged in an area of ​​the power board 4 where the power elements 40 are not arranged (an area different from the power elements 40). In other words, the connection portion 415 is arranged in an area of ​​the power board 4 where it does not overlap with the power elements 40 in the Y direction. The width W2 is an example of a "first width." The width W1 is an example of a "second width."

[0018] 7A and 7B are diagrams illustrating an example of the input electrode bus bar 42. FIG. 7A is a top view of the input electrode bus bar 42, and FIG. 7B is a side view of the input electrode bus bar 42. The input electrode bus bar 42 has extensions 423 and 424 that are parallel to each other, and a connection portion 425 that connects the extensions 423 and 424. The extensions 423 and 424 are members that extend in the Z direction. The connection portion 425 is a member that extends in the X direction. The connection portion 425 connects one end of the extension 423 to one end of the extension 424, and the input electrode bus bar 42 is formed in a U-shape in top view. The extensions 423 and 424 have screw holes 428, for example, two each aligned in the Z direction, into which screws 92 that fix the input electrode bus bar 42 to the power board 4 are inserted. Furthermore, the extensions 423 and 424 have screw holes 428 formed side by side in the Z direction, for example, into which screws 91 are inserted to fix the capacitor substrate 3 to the power substrate 4. A reinforcing portion 427 is formed at the end of the input electrode 421 on the extension 423 side, reinforcing the connection between the input electrode 421 and the extension 423. Because the input electrode bus bar 42 is formed of a conductor, power input via the input electrode 421 is supplied to the extensions 423 and 424 and the connection portion 425. A height H3 of the extensions 413, 414, 423, and 424 is greater than a height H2 of the output electrode bus bars 51, 52, and 53, and the capacitor substrate 3 is supported by the extensions 413, 414, 423, and 424, thereby forming gaps C1 (see FIG. 4 ) that ensure an insulation distance between the capacitor substrate 3 and the output electrode bus bars 51, 52, and 53.

[0019] The input electrode 421 is provided at the end of the extension portion 423 in the +Z direction so as to protrude upward. The connection portion 425 includes a thin portion 426A and a base portion 426B. The base portion 426B is disposed on the extension portion 423 side of the connection portion 425. The thin portion 426A is disposed on the extension portion 424 side of the connection portion 425. The thin portion 426A is formed to be thinner in the Y direction than the base portion 426B. As can be seen from FIG. 7B , the extension portions 423 and 424 are trapezoidal when viewed in the Z direction, with the width W1 of the upper base being larger than the width W2 of the lower base. The width W1 of the upper base is determined so that the distance between the screw hole 428 and the ends 423A and 424A of the extension portions 423 and 424 is a predetermined distance that ensures the rigidity of the input electrode bus bar 42. That is, the opening of the screw hole 428 on the surface (top surface) of the input electrode bus bar 42 opposite to the surface (bottom surface) facing the power board 4 is formed smaller than the width W1 of the upper base. Also, the opening of the screw hole 428 on the surface of the input electrode bus bar 42 facing the power board 4 is formed smaller than the width W2 of the lower base. As can be understood with reference to FIG. 5 , the connection portion 425 is arranged in an area of ​​the power board 4 where the power elements 40 are not arranged (an area different from the power elements 40). In other words, the connection portion 425 is arranged in an area of ​​the power board 4 where it does not overlap with the power elements 40 in the Y direction. The input electrode bus bars 41, 42 are an example of a "bus bar".

[0020] 8A and 8B are diagrams illustrating the arrangement of input electrodes 411 and 421 in inverter circuit 200. Input electrodes 411 and 421 are arranged so that extensions 413, 414, 423, and 434 are parallel to one another. Here, input electrodes 411 and 421 are arranged so that thin-walled portions 416A and 426A are vertically overlapping. A gap C2 is formed between thin-walled portions 416A and 426A, ensuring an insulating distance. Therefore, input electrodes 411 and 421 are insulated from one another even when thin-walled portions 416A and 426A are vertically overlapping. As a result of this arrangement, extension 424 is arranged between extensions 413 and 414, and extension 414 is arranged between extensions 423 and 424. That is, the extensions 413 and 414 of the input electrode bus bar 41 and the extensions 423 and 424 of the input electrode bus bar 42 are arranged alternately.

[0021] Returning to FIG. 5 , the output electrode bus bars 51, 52, and 53 are plate-shaped members extending in the Z direction parallel to the extension portion 413. The output electrode bus bars 51, 52, and 53 are formed of a conductor such as metal. The output electrode bus bar 51 is disposed between the extension portions 413 and 424. An output electrode 511 is provided at the −Z direction end of the output electrode bus bar 51 so as to protrude upward. The output electrode bus bar 52 is disposed between the extension portions 424 and 414. An output electrode 521 is provided at the −Z direction end of the output electrode bus bar 52 so as to protrude upward. The output electrode bus bar 53 is disposed between the extension portions 414 and 423. An output electrode 531 is provided at the −Z direction end of the output electrode bus bar 53 so as to protrude upward.

[0022] On the power board 4, electrode groups D1, D2, D3, D4, D5, and D6, in which the power elements 40 are aligned in a row in the Z direction, are arranged parallel to each other. The electrode groups D1, D2, D3, D4, D5, and D6 are used as upper and lower arm switching elements for each phase of the three-phase AC output by the inverter device 100. The electrode group D1 is arranged between the extension 413 and the output electrode bus bar 51. The power elements 40 belonging to the electrode group D1 are electrically connected to the extension 413 and the output electrode bus bar 51. The extension 413 can be said to be arranged adjacent to the electrode group D1. The electrode group D2 is arranged between the output electrode bus bar 51 and the extension 424. The power elements 40 belonging to the electrode group D2 are electrically connected to the output electrode bus bar 51 and the extension 424. The electrode group D3 is arranged between the extension 424 and the output electrode bus bar 52. The extension 424 can be said to be arranged adjacent to the electrode group D2. The power elements 40 belonging to the electrode group D3 are electrically connected to the extension 424 and the output electrode bus bar 52. The extension 424 can be said to be arranged adjacent to the electrode group D3. The electrode group D4 is arranged between the output electrode bus bar 52 and the extension 414. The power elements 40 belonging to the electrode group D4 are electrically connected to the output electrode bus bar 52 and the extension 414. The extension 414 can be said to be arranged adjacent to the electrode group D4. The electrode group D5 is arranged between the extension 414 and the output electrode bus bar 53. The power elements 40 belonging to the electrode group D5 are electrically connected to the extension 414 and the output electrode bus bar 53. The extension 414 can be said to be arranged adjacent to the electrode group D5. The electrode group D6 is arranged between the output electrode bus bar 53 and the extension 423. The power elements 40 belonging to the electrode group D6 are electrically connected to the output electrode bus bar 53 and the extension portion 423. It can be said that the extension portion 423 is disposed adjacent to the electrode group D6.

[0023] In other words, the output electrode bus bar 51 including the output electrode 531 that outputs the U phase is sandwiched between the electrode group D1 that forms the upper arm of the U phase and the electrode group D2 that forms the lower arm of the U phase. The output electrode bus bar 52 including the output electrode 521 that outputs the V phase is sandwiched between the electrode group D4 that forms the upper arm of the V phase and the electrode group D3 that forms the lower arm of the V phase. The output electrode bus bar 53 including the output electrode 531 that outputs the W layer is sandwiched between the electrode group D5 that forms the upper arm of the W layer and the electrode group D6 that forms the lower arm of the W layer.

[0024] FIG. 9 is a diagram schematically illustrating the flow of current input from the input electrode 411. In FIG. 9, the flow of current input from the input electrode 411 to the output electrode 531 is schematically indicated by arrows A1, A2, and A3. The current input from the input electrode 411 passes through the connection portion 415 and the extension portion 414 and is input to each of the power elements 40, 40, and 40. The current input to each of the power elements 40, 40, and 40 flows into the output electrode bus bar 51. The current flowing into the output electrode bus bar 51 is output from the output electrode 531. In this embodiment, by arranging the input electrode 411 and the output electrode 531 opposite each other on the power board 4, the distance of the current path between the input electrode 411 and the output electrode 531 passing through the power elements 40, 40, and 40 is averaged. Therefore, the current flowing through the power elements 40, 40, and 40 is also averaged, thereby improving the reliability of the power elements 40, 40, and 40. Although the current path input from the input electrode 411 and flowing to the output electrode 531 has been described in FIG. 9, the same applies to the current paths of other combinations of input electrodes and output electrodes.

[0025] FIG. 10 is a diagram schematically illustrating the arrangement of the extension 413, the output electrode bus bar 51, and the power element 40 in this embodiment. FIG. 10 illustrates the arrangement of the extension 413, the output electrode bus bar 51, and the power element 40 as viewed from the side. FIG. 10 also illustrates, with dotted lines, a screw hole 418 formed in the extension 413 of the input electrode bus bar 41, a screw 92 inserted into the screw hole, and an insulating washer 93. The screw hole 418 is formed with a wider diameter at the top to receive the head of the screw 92. The screw hole 418 is also formed with a narrower diameter at the bottom, into which the threaded portion of the screw 92 is inserted. That is, the screw hole 418 is formed in a stepped shape when viewed in the Z direction. The insulating washer 93 is a washer made of an insulating material. The screw 92 is inserted into the screw hole 418 while being inserted into the insulating washer 93. That is, an insulating washer 93 is disposed between the screw 92 and the screw hole 418, and the screw 92 and the screw hole 418 do not come into contact with each other. Therefore, the screw 92 and the screw hole 418 are insulated from each other. The screw 92 penetrates the power board 4 in the thickness direction and reaches the heat sink 12, thereby fixing the power board 4 and the heat sink 12 together. The insulating washer 93 is an example of a "washer."

[0026] 10 , the output electrode bus bar 51 is also formed in a trapezoidal shape when viewed in the Z direction, similar to the extension portion 413, with the width W3 of the upper base being larger than the width W4 of the lower base. In addition, the height H2 of the output electrode bus bar 51 is larger than the height H1 of the power element 40.

[0027] By forming the extension 413 and the output electrode bus bar 51 in this manner, the power element 40 can be arranged so as to slip under the −X-direction end 413A of the extension 413, and can also be arranged so as to slip under the +X-direction end 51A of the output electrode bus bar 51. In other words, the power element 40 is arranged so that a partial area of ​​the power element 40 overlaps with the extension 413 and the output electrode bus bar 51 when viewed in the Y direction. As a result, the packaging density of the extension 413, the power element 40, and the output electrode bus bar 51 can be increased.

[0028] When manufacturing the inverter device 100, the input electrode bus bars 41, 42 and the power board 4 are fixed together with the screws 92 inserted into the screw holes 418, 428, and then the positive terminal of the power supply is connected to the input terminal 412 and the negative terminal of the power supply is connected to the input terminal 422.

[0029] <Effects of the Embodiment> In the present embodiment, the input electrode bus bars 41, 42 arranged on the power board 4 have extensions 413, 414 and extensions 423, 424 that are parallel to each other. The extension 424 is arranged between the extensions 413 and 414, and the extension 414 is arranged between the extensions 423 and 424. The input electrode bus bars 41, 42 are arranged so that the thin portions 416A, 426A of the connection portions 415, 425 overlap each other. By arranging the input electrode bus bars 41, 42 in this manner, power can be supplied from the input electrodes 411, 421 via the connection portions 415, 425 and the extensions 414, 424, even to a power element 40 arranged near the center of the power board 4, for example, without passing through another board such as the capacitor board 3. According to this embodiment, the power supply path to the power element 40 can be formed on the power board 4 without passing through the capacitor board 3, so the thermal effects on the capacitor board 3 and the capacitor 30 can be suppressed compared to when power is supplied to the power element 40 via the capacitor board 3.

[0030] In this embodiment, the thin portions 416A, 426A that are arranged to overlap in the Y direction are formed thinner than the base portions 416B, 426B. Therefore, according to this embodiment, it is possible to suppress an increase in the height direction (Y direction) of the inverter device 100. Furthermore, in this embodiment, a gap C2 is formed between the thin portions 416A, 426A, so that the input electrode bus bars 41, 42 can be insulated from each other without using an insulating spacer or the like.

[0031] In this embodiment, a plurality of power elements 40 are arranged parallel to the extensions 413, 423, 414, and 424 between the extensions 413, 423, 414, and 424, and the output electrode bus bars 51, 52, and 53 are arranged parallel to the extensions 413, 423, 414, and 424. The input electrodes 411, 421 and the output electrodes 511, 521, and 531 are arranged to sandwich the power elements 40 in the direction in which the power elements 40 are arranged. By arranging the input electrodes 411, 421 and the output electrodes 511, 521, and 531 in this manner, the distance of the current path between the input electrodes 411, 421 and the output electrodes 511, 521, and 531 via each power element 40 is averaged. As a result, the current flowing through each power element 40 is also averaged, thereby improving the reliability of the power elements 40.

[0032] In this embodiment, the connection portions 415, 425 of the input electrode bus bars 41, 42 are arranged in an area of ​​the power board 4 that is different from the area in which the power elements 40 are arranged. By arranging the connection portions 415, 425 in this manner, an increase in the height direction (Y direction) of the inverter device 100 can be suppressed.

[0033] In this embodiment, the capacitor substrate 3 is supported by the extensions 413, 414, 423, and 424 of the input electrodes 411 and 421 so that a gap C1 is formed between the output electrode bus bars 51, 52, and 53 and the capacitor substrate 3. By forming the gap C1, the capacitor substrate 3 and the output electrode bus bars 51, 52, and 53 can be insulated from each other without using an insulating spacer or the like.

[0034] In this embodiment, the width W1 of the upper base is larger than the width W2 of the lower base of the input electrode bus bars 41, 42. In other words, the width W2 of the lower base of the input electrode bus bars 41, 42 is smaller than the width W1 of the upper base. This makes it possible to maximize the area in which the power elements 40 are mounted between the extensions 413, 423, 414, and 424, and ultimately to maximize the mounting density of the power elements 40.

[0035] In this embodiment, when viewed in the Y direction, the power elements 40 are arranged so that a portion of the power elements 40 overlaps with the extension portion 413. As a result, according to this embodiment, the packaging density of the power elements 40 can be increased.

[0036] In this embodiment, the width W1 of the upper base is determined so that the distance between the screw hole 418 and the ends 413A, 414A of the extensions 413, 414 is a predetermined distance that ensures the rigidity of the input electrode bus bar 41. Therefore, even if torque is generated by turning the screw 92 inserted into the screw hole 418, the rigidity against the torque can be ensured.

[0037] In this embodiment, the screw 92 is inserted into the screw hole 418 while being inserted into the insulating washer 93. In other words, the insulating washer 93 is disposed between the screw 92 and the screw hole 418, and the screw 92 does not come into contact with the screw hole 418. Therefore, according to this embodiment, the screw 92 and the screw hole 418 can be insulated from each other.

[0038] In this embodiment, screw holes 419, 429 for fixing the capacitor board 3 to the input electrode bus bars 41, 42 are formed in the extensions 413, 423. Therefore, according to this embodiment, the capacitor board 3 can be easily fixed to the power board 4.

[0039] <Modifications> In the embodiment, the extensions 413, 414, 423, and 424 of the input electrode bus bars 41 and 42 are formed in a trapezoidal shape when viewed in the Z direction. However, the extensions 413, 414, 423, and 424 may be formed in a shape other than a trapezoid. FIG. 11 illustrates variations in the shape of the extension 413 when viewed in the Z direction. In FIG. 11A , a stepped portion 4132 is provided above a trapezoidal base 4131. The stepped portion 4132 is formed so that the diameter of the extension 413 gradually increases in the +Y direction. In FIG. 11B , an inclined surface 4133 is formed on the surface of the extension 413 facing the power element 40. The inclined surface 4133 is formed so that the diameter of the extension 413 gradually increases in the +Y direction. The extensions 413 illustrated in FIGS. 11A and 11B can also increase the mounting density of the power elements 40 while ensuring the strength around the screw holes 428. The same applies to the extensions 414, 423, and 424.

[0040] In the embodiment described above, electronic components such as the capacitor 30 and the power element 40 are mounted on each of the control board 2, the capacitor board 3, and the power board 4. However, the inverter device 100 is not limited to this configuration. For example, the inverter device 100 may consolidate the boards included in the inverter device 100 into a single board by mounting the electronic components mounted on the control board 2 and the capacitor board 3 on the power board 4.

[0041] Furthermore, in the above-described embodiment and modified examples, the extensions 413, 414, 423, and 424 are formed so that the width W1 of the upper base is larger than the width W2 of the lower base, but the entire input electrode bus bars 41 and 42 may be formed so that the width W1 of the upper base is larger than the width W2 of the lower base in a cross-sectional view.

[0042] The features of the present invention are described as supplementary notes below. (Supplementary note 1) An electronic device comprising: a substrate on which electronic components are mounted; and a bus bar arranged on the substrate, having a top surface wider than a bottom surface in contact with the substrate, and fixed to the substrate with a screw inserted into a step-shaped through hole, wherein the screw head is fixed at a step in the step-shaped through hole, and the height of the electronic component is lower than the top surface of the bus bar, and at least a portion of the electronic component is mounted so as to overlap the top surface of the bus bar. (Supplementary note 2) The electronic device according to Supplementary note 1, wherein the width of the top surface is wider than an opening of the through hole formed in the top surface. (Supplementary note 3) The electronic device according to Supplementary note 1, wherein a washer made of an insulating material is arranged between the through hole and the screw. (Supplementary note 4) The electronic device according to any one of Supplements 1 to 3, further comprising an upper substrate arranged on the side of the substrate on which the bus bar is arranged, and wherein the bus bar has a second screw hole formed in the bus bar for fixing to the upper substrate. (Supplementary Note 5) The electronic device according to Supplementary Note 1, wherein the screw secures the bus bar, the substrate, and the housing. (Supplementary Note 6) The electronic device according to Supplementary Note 1, wherein the bus bar includes an electrode having a third screw hole, and the electrode is exposed to the outside of the housing through a hole provided in the housing and connected to a power supply terminal. (Supplementary Note 7) The electronic device according to Supplementary Note 1, wherein the electronic device is an inverter. (Supplementary Note 8) A method for manufacturing an electronic device according to Supplementary Note 6, comprising: after securing the through hole of the bus bar to the substrate with a screw, securing the third screw hole of the bus bar to the power supply terminal with a screw.

[0043] DESCRIPTION OF SYMBOLS 2: Control board 3: Capacitor board 4: Power board 11: Housing 12: Heat sink 13: Cover 14: Breathing valve 15: Connection terminal 30: Capacitor 31: Recess 32: Recess 33: Recess 35: Recess 36: Recess 40: Power element 41: Input electrode bus bar 42: Input electrode bus bar 51: Output electrode bus bar 52: Output electrode bus bar 53: Output electrode bus bar 111: Claw portion 112: Claw portion 113: Claw portion 131: Through hole 132: Through hole 133: Through hole 134: Through hole 135: Through hole 136: Claw portion 137: Claw portion 138: Claw portion 100: Inverter device 200: Inverter circuit 411: Input electrode 412: Input terminal 413: Extension portion 414: Extension portion 415: Connection portion 416A: Thin portion 416B: Base portion 417: Reinforcement portion 421: Input electrode 422: Input terminal 423: Extension portion 424: Extension portion 425: Connection portion 426A: Thin portion 426B: Base portion 427: Reinforcement portion 511: Output electrode 512: Output terminal 521: Output electrode 522: Output terminal 531: Output electrode 532: Output terminal 91: Screw 92: Screw 93: Insulating washer D1: Electrode group D2: Electrode group D3: Electrode group D4: Electrode group D5: Electrode group D6: Electrode group

Claims

1. An electronic device comprising: a substrate on which electronic components are mounted; and a busbar arranged on the substrate, the busbar having a top surface wider than a bottom surface in contact with the substrate, and the busbar fixed to the substrate with a screw inserted into a step-shaped through hole, wherein a head of the screw is fixed at a step of the step-shaped through hole, the height of the electronic components is lower than the top surface of the busbar, and at least a portion of the electronic components is mounted so as to overlap the top surface of the busbar.

2. The electronic device according to claim 1, wherein the width of the upper surface is formed wider than the opening of the through hole formed in the upper surface.

3. The electronic device according to claim 1, wherein a washer made of an insulating material is disposed between the through hole and the screw.

4. The electronic device according to any one of claims 1 to 3, further comprising an upper substrate arranged on the side of the substrate on which the bus bar is arranged, and a second screw hole is formed in the bus bar for fastening it to the upper substrate.

5. The electronic device according to claim 1, wherein the screw fastens the bus bar, the substrate, and the housing.

6. The electronic device according to claim 1, wherein the bus bar includes an electrode having a third screw hole, the electrode being exposed to the outside of the housing through a hole provided in the housing and connected to a power supply terminal.

7. The electronic device according to claim 1, wherein the electronic device is an inverter.

8. A method for manufacturing an electronic device as described in claim 6, comprising the steps of: fixing the through hole of the bus bar to the substrate with a screw; and then fixing the third screw hole of the bus bar to the power terminal with a screw.

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