Power circuit

Abstract

To provide a power supply circuit with which it is possible to suppress corona discharges.SOLUTION: A power supply circuit according to the present invention comprises: a plurality of switching elements that includes a body part, a first terminal to which the voltage of first potential is applied, a second terminal that is electrically connected to the first terminal when turned on, and a third terminal to which is inputted a voltage signal for controlling the on / off state; a first circuit board on which the switching elements are mounted so as to be connected in series; a drive circuit that drives the switching elements; a first connection part that electrically connects the second terminals of the switching elements and the first potential part of the drive circuit; a conductive member of a reference potential; and a first insulating member that is located between the conductive member of the reference potential and the first circuit board.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a power supply circuit.

Background Art

[0002] In a plasma processing apparatus used in a process for manufacturing a semiconductor wafer or a liquid crystal substrate, for example, a power supply device for generating a high voltage is provided, such as a pulse power supply device for generating a pulsed voltage (pulse voltage) (see, for example, Patent Document 1).

[0003] The pulse power supply device is configured to, for example, convert DC power into AC power by an inverter circuit, then convert the AC power into AC power with different voltage values by a transformer, rectify and smooth it, and further generate a pulse voltage by a switching circuit or the like. In the pulse power supply device as described above, a high voltage with an absolute value of about 10 kV is applied to a switching element such as a MOSFET used in a high voltage application circuit. Components such as switching elements are mounted on a circuit board.

[0004] In addition, in a power supply device for generating a high voltage, by connecting switching elements in multiple stages in series, the input high voltage is shared by these switching elements for switching. When connecting switching elements in multiple stages in series, an insulation power supply and a gate drive circuit are required according to each switching element, resulting in an increase in size, so it is necessary to effectively utilize the space inside the housing. Therefore, considering the switching element and its cooling, it is desirable that the substrate to which the switching element is connected is horizontally arranged with the cooler of the switching element, and the circuit board provided with the gate drive circuit and the insulation power supply is vertically arranged.

[0005] Furthermore, considering the complexity of the process and ease of manufacturing, it is better to initially manufacture the boards with the switching elements attached and the circuit board containing the gate drive circuit and isolated power supply separately, and then connect the two boards afterward. For this reason, these two boards are often ultimately connected by pins or screws, and from a durability standpoint, through-hole components that are firmly soldered to the board are preferred over surface-mount components. Incidentally, in switching that generates high voltage, corona discharge can occur from the metal terminals of the switching elements.

[0006] One example of a document disclosing a technology for suppressing corona discharge is Patent Document 2. This Patent Document 2 discloses a technology for preventing the occurrence of corona discharge caused by the concentration of an electric field in the air gap (part of the screw hole) around a screw (ground potential) in a high-voltage application circuit that includes components such as switching elements. Specifically, corona discharge is suppressed by inserting a ground potential conductor between the air gap around the screw and the high-potential area, thereby eliminating the concentration of the electric field in the air gap. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2013-125729 [Patent Document 2] Japanese Patent Publication No. 2018-067644 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, the aforementioned Patent Document 2 only addresses the air gap around the screw. Furthermore, the applied voltage is approximately 3.3kV, which is relatively low compared to approximately 10kV. When a high voltage of 10kV or more is applied, corona discharge becomes even more likely. For this reason, it is necessary to take measures to prevent corona discharge between a high-potential area of ​​a component to which a high voltage of 10kV or more is applied, or a high-potential area of ​​a circuit board (such as a circuit board pattern) that is at the same potential as such a high-potential area, and a component at ground potential.

[0009] The present invention has been made in view of these problems, and aims to provide a power supply circuit that can suppress corona discharge between a high-potential portion of a component to which a high voltage (for example, a voltage with an absolute value of 10kV or more) is applied, or a high-potential portion of a circuit board that is at the same potential as the high-potential portion, and a component at ground potential. [Means for solving the problem]

[0010] The power supply circuit according to the present invention comprises a main body, a plurality of switching elements having a first terminal to which a voltage of a first potential is applied, a second terminal electrically connected to the first terminal when turned ON, and a third terminal for inputting a voltage signal to control the ON / OFF state, a first circuit board on which the switching elements are mounted in series, a drive circuit for driving the switching elements, a first connection part that electrically connects the second terminal of the switching element and the first potential part of the drive circuit, a conductive member of a reference potential, and a first insulating member disposed between the conductive member of the reference potential and the first circuit board, wherein the main body of the switching element has a metal surface of the same potential as the first potential part and is positioned on the first insulating member away from the first circuit board with the metal surface facing the first circuit board, and the first connection part has a first projection that protrudes toward the metal surface relative to the first circuit board and is provided at a position where the first projection faces the metal surface. [Effects of the Invention]

[0011] According to the present invention, in a power supply circuit, corona discharge can be suppressed between a first high-potential portion of a component to which a high voltage (for example, a voltage with an absolute value of 10kV or more) is applied, or a first high-potential portion of a circuit board that is at the same potential as the first high-potential portion of the component, and a member at ground potential. The effects described herein are not necessarily limited, and any of the effects described herein may also be present. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 shows an example of the configuration of a power supply circuit according to the embodiment. [Figure 2] Figure 2 shows an example of the configuration of the first switching unit of the embodiment. [Figure 3] Figure 3 shows an example of the configuration of the second circuit board of the embodiment. [Figure 4] Figure 4 is a schematic diagram showing an example of the configuration of the switching element in the embodiment. [Figure 5] Figure 5 shows an example of the arrangement of the power supply circuit in the embodiment. [Figure 6] Figure 6 shows an example of the configuration of the switching element and the first circuit board of the embodiment. [Figure 7] Figure 7 shows the simulation results of the power supply circuit of the embodiment. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments of the power supply circuit according to the present invention will be described with reference to the drawings. However, the present invention is not limited by these embodiments. In the following embodiments, parts with the same reference numerals are considered equivalent, and redundant explanations will be omitted as appropriate.

[0014] Figure 1 shows an example of the configuration of a power supply circuit 100. The power supply circuit 100 has a first switching unit 10, a second switching unit 20, an output terminal 30, and an output node 40. In Figure 1(a), when the first switching unit 10 is ON, the second switching unit 20 is OFF. Also, when the second switching unit 20 is ON, the first switching unit 10 is OFF.

[0015] In the example of Fig. 1(a), the potential difference between the potential of the high-potential terminal and the potential of the low-potential terminal of the DC power supply that supplies a DC voltage to the power supply circuit 100 is 12 kV. Since the low-potential terminal of the DC power supply is connected to the ground potential (0 V), the potential of the high-potential terminal becomes 12 kV. That is, the output voltage of the DC power supply is +12 kV. Therefore, 12 kV and 0 V are alternately output from the output terminal 30 of the power supply circuit 100. Also, there is a dead time when switching between ON and OFF in the first switching unit 10 and the second switching unit 20. Note that the 12 kV of the output voltage of the DC power supply is an example, and other voltages (for example, 10 kV or more) may be used.

[0016] Also, as shown in Fig. 1(b), the high-potential terminal of the DC power supply may be connected to the ground potential (0 V), the potential of the low-potential terminal may be set to -12 kV, and the output voltage of the DC power supply may be set to -12 kV. In this case, -12 kV and 0 V are alternately output from the output terminal 30 of the power supply circuit 100. In the present embodiment, it is assumed that the potential difference between the potential of the high-potential terminal and the potential of the low-potential terminal of the DC power supply that supplies a DC voltage to the power supply circuit 100 is 10 kV or more, but it can also be applied even if it is less than 10 kV.

[0017] The power supply circuit that generates a pulsed voltage (pulse voltage) shown in Fig. 1(a) and Fig. 1(b) can be applied to, for example, a pulse power supply device used when performing plasma processing in a semiconductor manufacturing process (see Patent Document 1). Note that the frequency of the pulsed voltage waveform is about several hundred kHz, but various frequencies are used depending on the application. For example, it may be about several tens of kHz or about 1 MHz.

[0018] FIG. 2 is a diagram showing an example of the configuration of the first switching unit 10. FIG. 2 illustrates the first switching unit 10 shown in FIG. 1(a), and as an example, six switching elements 111 (FETs) are connected in series. Note that the number of switching elements 111 (FETs) is an example, and other numbers are also possible. In FIG. 2, six switching elements 110 (FETs) are mounted on the first circuit board 110 (hereinafter also referred to as the FET board), but it is not limited thereto. For example, when the number of switching elements 111 (FETs) is large, it may be divided into a plurality of first circuit boards 110 (FET boards). In the present embodiment, a field effect transistor (FET: Field effect transistor) is exemplified as the switching element 111, but it is not limited to the field effect transistor.

[0019] Also, the second switching unit 20 has the same configuration as the first switching unit 10. However, the applied potential is different. These switching elements 110 (FETs) are controlled by a gate drive circuit 121 (an example of a drive circuit) so as to be turned on or off simultaneously. In FIG. 2, six gate drive circuits 121 and an isolated DC-DC converter 122 are mounted on the second circuit board 120 (hereinafter also referred to as the driver board). The voltage (potential difference ǀ24Vǀ) supplied between the gate and source of each switching element 111 (FET) via the gate drive circuit 121 is supplied from the isolated DC-DC converter 122. Also, the control signal to the gate drive circuit 121 is sent from another device (circuit) not shown. The gate drive circuit 121 controls the gate voltage according to the sent control signal. Note that illustration of a control unit or the like for control is omitted.

[0020] The isolated DC-DC converter 122 incorporates a transformer (not shown) inside, and the transformer can insulate the primary side (input side) and the secondary side (output side). For example, when the power consumed by the gate drive circuit 121 is large, a capacitor 123 may be inserted between the gate drive circuit 121 and the isolated DC-DC converter 122.

[0021] Next, the operation of the first switching unit 10 will be described. In Figure 1(a), when each switching element 111 (FET) of the first switching unit 10 is turned ON, the drain and source are electrically connected, and a high voltage of 12kV is applied to the output terminal of the isolated DC-DC converter 122. Also, when each switching element 111 (FET) of the first switching unit 10 is turned OFF, each switching element (FET) of the second switching unit 20 is turned ON, and the output node 40 becomes 0V (ground potential), so a potential difference of 12kV is generated in the first switching unit 10. This potential difference is shared by the switching elements constituting the first switching unit 10, so a potential difference is generated between the drain and source.

[0022] In the case of Figure 2, the source potentials of each switching element 111 are 10kV, 8kV, 6kV, 4kV, 2kV, and 0kV from top to bottom. The first circuit board 110 should determine the number of switching elements 111 (FETs) by considering this potential difference and the breakdown voltage of the switching elements 111 (FETs). Also, as in Figure 1(b), when a negative potential is applied and each switching element 111 (FET) of the first switching unit 10 is off, the source potentials are -2kV, -4kV, -6kV, -8kV, -8kV, and -12kV from top to bottom.

[0023] Next, the operation of the second switching unit 20 will be explained. In Figure 1(a), when each switching element 111 (FET) of the first switching unit 10 is ON, each switching element 111 (FET) of the second switching unit 20 is OFF. In this case, the output node becomes 12kV, so a potential difference of 12kV is generated in the second switching unit 20. This potential difference is shared by the switching elements 111 that make up the second switching unit 20, so a potential difference is generated between the drain and the source. If the second switching unit 20 is composed of six switching elements 111 (FETs), then, similar to the first switching unit 10, the potentials of the sources of each switching element 111 will be 10kV, 8kV, 6kV, 4kV, 2kV, and 0kV from top to bottom.

[0024] When each switching element 111 (FET) of the first switching unit 10 is OFF, each switching element 111 (FET) of the second switching unit 20 is ON. In this case, each switching element 111 (FET) is connected to ground potential, so the drain and source become 0kV. When a negative potential is applied as shown in Figure 1(b), and each switching element 111 (FET) of the first switching unit 10 is ON, the source potentials are -2kV, -4kV, -6kV, -8kV, -8kV, and -12kV from top to bottom.

[0025] Figure 3 shows an example of the configuration of the second circuit board 120. While Figure 2 shows the entire first switching unit 10, Figure 3 describes the gate drive circuit 121 and isolated DC-DC converter 122 corresponding to one switching element 111. Note that in Figure 3, the capacitor 123 between the gate drive circuit 121 and the isolated DC-DC converter 122, which is shown by a dotted line in Figure 2, is omitted.

[0026] The isolated DC-DC converter 122 is connected in series in multiple units (for example, three) to distribute the high voltage of 12kV due to voltage withstand capability issues. The output of the isolated DC-DC converter 122 has a potential difference 124 of 24V. The gate drive circuit 121 (excluding the control unit and the external control signal input unit) controls the voltage applied to the gate of the switching element 111 (a voltage with a potential difference of 24V), as shown in Figure 3. Figure 3 shows the case when the switching element 111 is turned ON. Note that when the switching element 111 is ON in the first switching unit 10 in Figure 1(a), approximately 12,000V is applied to the source, so approximately 12,024V is applied to the gate.

[0027] Figure 4 is a schematic diagram showing an example of the configuration of a switching element 111. The switching element 111 has a main body 115 and a terminal section 116. One side of the main body 115 has a metal surface 117, and the potential of this metal surface 117 is the same as the potential of the drain. The terminal section 116 has a first terminal 112 (drain terminal), a second terminal 113 (source terminal), and a third terminal 114 (gate terminal). A voltage of first potential is applied to the first terminal 112. The second terminal 113 is electrically connected to the first terminal 112 when it is turned ON. The third terminal 114 receives a voltage signal to control the ON / OFF state.

[0028] Figure 5 shows an example of the arrangement of a power supply circuit. For the sake of simplicity in the following explanation, two mutually orthogonal directions in the horizontal plane will be referred to as the X-axis and Y-axis, and the vertical direction as the Z-axis. Figure 5(a) is a front view of the power supply circuit 100 in the power supply unit as seen from the X-axis direction. Figure 5(b) is a side view of the power supply circuit 100 in the power supply unit as seen from the Y-axis direction. In Figures 5(a) and 5(b), each terminal and wiring 127 is shown transparently. Details of the isolated DC-DC converter 122 are omitted. The input section for the input voltage (24V) is also omitted. Details of the gate drive circuit 121 are omitted. The control unit and the like are also omitted. Wiring 127 schematically shows pattern wiring, etc.

[0029] The power supply circuit 100 also includes a first circuit board 110, a second circuit board 120 positioned vertically relative to the first circuit board 110, a switching element 111 provided below the first circuit board 110, a second insulating member 130 covering the main body 115 of the switching element 111, a first insulating member 140 provided below the switching element 111 and positioned between the first circuit board 110 and the conductive member 150, and a conductive member 150 provided below the second insulating member 130. The second insulating member 130 is made of an insulating material (resin member) such as silicone or epoxy resin.

[0030] The first insulating member 140 is, for example, a ceramic, and is a flat plate-shaped member provided on the plane of the conductive member 150. Preferably, alumina or aluminum nitride is used, and in this embodiment, the thickness is 10 mm.

[0031] The conductive member 150 is, for example, a water-cooled copper plate and has a plane connected to a reference potential (0V). More specifically, the conductive member 150 is configured so that cooling water can circulate inside the flat copper plate. This enhances the cooling effect. The flat conductive member 150 is also connected to the ground potential.

[0032] The main body 115 of the switching element 111 has a metal surface 117 at the same potential as the first potential portion of the gate drive circuit 121 (the potential portion with the lower absolute value of the potential difference of 24V), and is positioned on the first insulating member, away from the first circuit board 110, with the metal surface 117 facing the first circuit board 110.

[0033] The terminal portion 116 of the switching element 111 is deformed (bent) by the second insulating member 130 that covers the main body portion 115 of the switching element 111 so that it faces the first circuit board 110. When a part of the terminal portion 116 is bent, it is preferable to avoid making it as sharp as possible. This is because sharp corners and other angular areas are more prone to charge concentration than rounded areas, and therefore corona discharge is more likely to occur. To prevent charge concentration at the bent portion, it is preferable to avoid making it as sharp as possible. In addition, since the bent portion is covered by the second insulating member 130, corona discharge can be made less likely to occur.

[0034] The first connection part 125 electrically connects the second terminal 113 of the switching element 111 to the first potential portion (the potential portion with the lower absolute value of the potential difference of 24V) of the gate drive circuit 121. The first connection part 125 also has a first protrusion 118 that projects toward the metal surface side of the first circuit board 110, and the first protrusion 118 is positioned facing the metal surface 117. The second connection part 126 electrically connects the third terminal 114 of the switching element 111 to the second potential portion (the potential portion with the higher absolute value of the potential difference of 24V) of the gate drive circuit 121. The second connection part 126 also has a second protrusion 119 that projects toward the metal surface side of the first circuit board 110, and the second protrusion 119 is positioned facing the metal surface 117.

[0035] For example, through-hole pins can be used for the first connection portion 125 and the second connection portion 126. The portions protruding downward from the first circuit board 110 (FET board) are the first protrusion portion 118 and the second protrusion portion 119, and for example, the tip portion of a through-hole pin protrudes to become the first protrusion portion 118 and the second protrusion portion 119.

[0036] By the way, in order to suppress corona discharge from the terminal portion 116 of the switching element 111, it is necessary to reduce the electric field strength. Here, we will explain the arrangement for reducing the electric field strength. Figure 6 is a diagram showing an example of the configuration of the switching element 111 and the first circuit board 110, and shows the switching element 111 and the first circuit board 110 as viewed from the Z direction (from the top surface), respectively.

[0037] Corona discharge can be suppressed by arranging the first protrusion 118 and the second protrusion 119 in the Z direction (facing each other) with respect to the arrangement area of ​​the metal surface 117 of the switching element 111 shown in Figure 6(a). This is because the potential of the metal surface 117 of the switching element 111 is the same as the potential of the first terminal 112 (drain terminal) of the switching element 111, so the charges repel each other and charge is less likely to concentrate on the first protrusion 118 and the second protrusion 119 of the first circuit board 110 (FET board). It is preferable to arrange the first protrusion 118 and the second protrusion 119 facing the recommended arrangement area 160 shown in Figure 6(a). The first circuit board 110 shown in Figure 6(b) shows the area of ​​the conductive part 170.

[0038] Figure 7 shows the simulation results of the power supply circuit. Figure 7(a) shows the simulation results of the power supply circuit 100 of this embodiment, and Figure 7(b) shows the simulation results of the power supply circuit of the comparative example. The power supply circuit of the comparative example is a power supply circuit in which the first protrusion 118 and the second protrusion 119 that protrude downward from the first circuit board 110 (FET board) are not placed in the arrangement area of ​​the metal surface 117 of the switching element 111, compared to the power supply circuit 100 of this embodiment.

[0039] The potentials applied to the conductive portion 170 of the first circuit board 110 (FET board) are of three types: the potential applied to the first terminal 112 (drain terminal), the potential applied to the second terminal 113 (source terminal), and the potential applied to the third terminal 114 (gate terminal). When each switching element 111 (FET) of the first circuit board 110 (FET board) is ON, the above three types of potentials are approximately the same, although there are slight differences. Also, the potential of the first protrusion 118 and the potential of the second protrusion 119 are approximately the same. Note that the above description assumes the first switching unit 10 in Figure 1(a) and the second switching unit 20 in Figure 1(b).

[0040] Therefore, considering the conductive portion 170 of the first circuit board 110 (FET board) as a single conductive portion, the electric field strength at the first protrusion 118 and the second protrusion 119 was simulated, and the results shown in Figure 7 were obtained. From the simulation results shown in Figure 7, it was confirmed that the electric field strength at the first protrusion 118 and the second protrusion 119 in the power supply circuit 100 of this embodiment (see Figure 7(a)) was significantly reduced. On the other hand, in the power supply circuit of the comparative example, the electric field strength at the first protrusion 118 and the second protrusion 119 (see Figure 7(b)) was high around the first protrusion 118 and the second protrusion 119.

[0041] As described above, in the power supply circuit 100 of this embodiment, the main body 115 of the switching element 111 has a metal surface 117 with the same potential as the first potential applied to the first terminal 112 (drain terminal), and is positioned on the first insulating member away from the first circuit board 110 (FET board) with the metal surface 117 facing the first circuit board 110 (FET board). The first connection part 125 has a first protrusion 118 that protrudes toward the metal surface side relative to the first circuit board 110 (FET board), and the first protrusion 118 is provided in a position facing the metal surface 117.

[0042] Therefore, in the power supply circuit 100 configured as in the above embodiment, the metal surface 117 of the switching element 111, which is at approximately the same potential as the first connection portion 125, exists between the first protrusion 118 and the conductive member 150 at the reference potential. As a result, corona discharge between the first protrusion 118 and the conductive member 150 is suppressed. This allows the power supply circuit 100 to suppress corona discharge.

[0043] While it is preferable that all first connection portions 125 having the first protrusion 118 have this positional relationship, the present invention is not invalidated even if there are first protrusions 118 that cannot be realized due to the circuit layout. In other words, it is possible to implement it for only some of the first protrusions 118.

[0044] Furthermore, as described above, the circuit also includes a second connection portion 126 that electrically connects the third terminal 114 (gate terminal) of the switching element 111 to the second potential portion of the gate drive circuit 121. The second connection portion 126 has a second protrusion 119 that protrudes toward the metal surface side of the first circuit board 110 (FET board), and the second protrusion 119 is positioned opposite the metal surface 117.

[0045] Therefore, the potential of the second connection portion 126 (and similarly the third terminal 114 (gate terminal)) has a predetermined potential difference (e.g., 24V) with respect to the first connection portion 125 (and similarly the second terminal 113 (source terminal)), so the second connection portion 126 also becomes high potential. As a result, corona discharge between the second protrusion 119 and the conductive member 150 at the reference potential can be suppressed. It is also possible to implement this only on some of the second protrusions 119.

[0046] Furthermore, as described above, the main body 115 of the switching element 111 is covered with the second insulating member 130. Therefore, when the voltage of the first potential is a high potential (for example, an absolute value of 10kV or more), using the second insulating member 130, which is effective as a measure against discharge, reduces the thickness of the air layer, making corona discharge more likely. However, in the present invention, even in such cases, the effect is maintained and corona discharge can be suppressed.

[0047] Furthermore, as described above, the device also includes a second circuit board 120 (driver board) on which the gate drive circuit 121 is mounted, and the second circuit board 120 is positioned vertically relative to the first circuit board 110. Therefore, the first connection portion 125 extends in a direction perpendicular to the in-plane direction of the first circuit board 110. In this positional relationship, even if a protrusion is created when the first circuit board 110 and the second circuit board 120 are connected, corona discharge can be suppressed.

[0048] Furthermore, as mentioned above, the reference potential is the ground potential, and the voltage of the first potential is a high voltage with an absolute value of 10kV or more. Therefore, corona discharge can be suppressed even when a high voltage with an absolute value of 10kV or more is applied to the first terminal 112 of the switching element 111. In experiments, it has been confirmed that corona discharge can be suppressed up to an absolute value of approximately 12kV. (Conventionally, corona discharge occurred at an absolute value of approximately 10kV.)

[0049] In this embodiment, the thickness of the first insulating member (ceramics) is 10 mm. Increasing this thickness increases the distance between the first connection portion 125 and the second connection portion 126 and the conductive member 150 at the reference potential. This works to suppress corona discharge. That is, it becomes possible to increase the applied potential (voltage), but since it moves further away from the conductive member 150, the cooling effect decreases. Therefore, the effect of the present invention in suppressing corona discharge without changing the thickness of the first insulating member (ceramics) is useful.

[0050] With respect to the above embodiments, the following additional notes are disclosed as aspects of the invention and selective features.

[0051] (Note 1) The contact surface between the conductive member with the reference potential and the first insulating member is flat. The contact surface between the first insulating member and the main body of the switching element is flat. The power supply circuit according to claim 1.

[0052] As described above, if each contact surface is flat, the contact area can be maximized, thereby improving the heat dissipation effect.

[0053] (Note 2) The first terminal, the second terminal, and the third terminal are deformed within the resin covering the main body of the switching element so that their terminal shapes face the first circuit board. The power supply circuit according to claim 2.

[0054] Corona discharge is more likely to occur at the bent terminals of the switching element, but by covering these areas with resin, it is possible to reduce the likelihood of corona discharge.

[0055] While embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These novel embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. Furthermore, the effects of the embodiments described herein are merely illustrative and not limiting, and other effects may also occur. [Explanation of symbols]

[0056] 100 Power circuit 110 1st circuit board 111 Switching elements 112 1st terminal 113 2nd terminal 114 3rd terminal 115 Main body of switching element 111 116 Terminal portion of switching element 111 117 Metal surface 118 1st protrusion 119 Second protrusion 120 2nd circuit board 121 Gate drive circuit 125 First connection section 126 Second connection section 130 Second insulating member 140 First insulating member 150 Conductive material

Claims

1. A main body, a first terminal to which a voltage of a first potential is applied, a second terminal that is electrically connected to the first terminal when turned ON, and a third terminal that receives a voltage signal to control the ON / OFF state, a plurality of switching elements, A first circuit board on which the switching elements are mounted in series, A drive circuit for driving the switching element, A first connection part electrically connects the second terminal of the switching element and the first potential part of the drive circuit, A conductive member with a reference potential, A first insulating member is disposed between the conductive member of the reference potential and the first circuit board, Equipped with, The main body of the switching element has a metal surface at the same potential as the first potential portion, and is positioned on the first insulating member, away from the first circuit board, with the metal surface facing the first circuit board. The first connecting portion has a first projection that protrudes toward the metal surface side relative to the first circuit board, and the first projection is provided at a position facing the metal surface. power circuit.

2. The circuit further comprises a second connection portion that electrically connects the third terminal of the switching element to the second potential portion of the drive circuit having a predetermined potential difference with respect to the first potential portion, The second connection part is, The voltage signal generated based on the potential of the first potential section and the potential of the second potential section is input to the third terminal. The first circuit board has a second projection that protrudes toward the metal surface, and the second projection is provided at a position facing the metal surface. The power supply circuit according to claim 1.

3. The main body of the switching element is covered with a second insulating member. The power supply circuit according to claim 1.

4. The circuit board further comprises a second circuit board on which the aforementioned drive circuit is mounted. The second circuit board is positioned vertically relative to the first circuit board. The power supply circuit according to claim 1.

5. The aforementioned reference potential is the ground potential. The voltage of the first potential is a high voltage with an absolute value of 10 kV or more. A power supply circuit according to any one of claims 1 to 4.

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