High voltage application circuit

Abstract

To provide a high voltage application circuit capable of suppressing corona discharge.SOLUTION: The high voltage application circuit comprises: a heat sink 10 having a plane connected to a ground potential; a flat-plate shaped ceramic plate 20 provided on the plate of a first metal member; a metal substrate 30; and an insulating resin 40 covering the metal substrate 30 except a first terminal 36 and a second terminal 37. The metal substrate 30 has a metal material 31, an insulating layer 32, a first conductive region 33 to which a first high voltage is applied, and a second conductive region 34 to which a second high voltage is applied, and an electric component 35 is mounted between the first conductive region 33 and the second conductive region 34, and the first terminal 36 and the second terminal 37 are formed. The metal substrate 30 is thermally connected to the heat sink 10 via the insulating resin 40 and the first terminal 36 and the second terminal 37 of the metal substrate 30 are provided on a side opposite to the ceramic plate 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a high voltage application circuit to which a high voltage is applied. [Background technology]

[0002] Plasma processing apparatuses used in the process of manufacturing semiconductor wafers or liquid crystal substrates are provided with a power supply device that generates a high voltage, such as a pulse power supply device that generates a pulsed voltage (pulse voltage) (see, for example, Patent Document 1). A pulse power supply device is configured, for example, to convert DC power into AC power using an inverter circuit, then convert it into AC power of a different voltage value using a transformer, rectify and smooth it using a rectifying and smoothing circuit, and further generate a pulse voltage using a switching circuit or the like. The pulse power supply device described above outputs a pulse voltage having a high voltage potential with an absolute value of approximately 10 kV. For this reason, there are parts in the rectifying and smoothing circuit and the switching circuit to which a high voltage with an absolute value of approximately 10 kV is applied (hereinafter referred to as high potential parts). As is well known, the higher the applied voltage, the more likely corona discharge occurs, so corona discharge must be suppressed in high voltage application circuits used in such high potential parts.

[0003] For example, Patent Document 2 discloses a technique for suppressing corona discharge. Patent Document 2 discloses a technique for suppressing corona discharge caused by electric field concentration in a gap (part of a screw hole) around a screw (ground potential) in a high-voltage application circuit that includes components such as a switching element. Specifically, a conductor at ground potential is inserted between the gap around the screw and the high-potential part, thereby eliminating electric field concentration in the gap and suppressing corona discharge. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-125729 [Patent Document 2] Japanese Patent Application Publication No. 2018-067644 Summary of the Invention [Problem to be solved by the invention]

[0005] However, Patent Document 2 only addresses the gap around the screw. In addition, the applied voltage is about 3.3 kV, which is a relatively low voltage. On the other hand, when a high voltage of, for example, 10 kV or more in absolute value is applied, corona discharges are more likely to occur, so measures must be taken to prevent corona discharges from occurring between high-potential areas (such as conductive areas of a metal substrate) where high voltage is applied and components at ground potential. Corona discharges are particularly likely to occur from terminals and angular areas of components, so measures to suppress corona discharges in these areas are necessary.

[0006] The present invention has been made in view of the above-mentioned problems, and aims to provide a high-voltage application circuit that can suppress corona discharge between a high-potential portion to which a high voltage is applied and a member at ground potential. [Means for solving the problem]

[0007] The high voltage application circuit according to the present disclosure comprises: a first metal member having a plane connected to a ground potential; A flat plate-shaped plate provided on the plane of the first metal material Ceramic plate and, A second metal material, an insulating layer, Absolute value is 10kV or more a first conductive region to which a first high voltage is applied and a second conductive region to which a second high voltage is applied; Absolute value is 10kV or more a metal substrate having a second conductive region to which a second high voltage is applied, an electrical component mounted between the first conductive region and the second conductive region, and on which a first terminal electrically connected to the first conductive region and a second terminal electrically connected to the second conductive region are formed; covering the metal substrate except for the first terminal and the second terminal Hardening insulating resin and, The metal substrate is Ceramic platethe first metal material is provided on the opposite side of the first metal material, the metal substrate Among the members constituting the above, the second metal material is disposed at a position closest to the ceramic plate, The second metal material is connected to the ceramic plate via a part of the hardenable insulating resin. is thermally connected to the insulating layer is disposed on an upper surface of the second metal material; the first conductive region and the second conductive region are disposed on an upper surface of the insulating layer; The aforementioned First terminal and The aforementioned The second terminal is Ceramic plate It is located on the opposite side. Reason 1 (clarity) ·Claims 1-4 Claim 1 states, "...comprises a flat-plate-shaped first insulating material provided on a plane of the first metal material;...a metal substrate; and a second insulating material covering the metal substrate except for the first terminal and the second terminal, the metal substrate being provided on the opposite side of the first insulating material from the first metal material, the surface of the metal substrate close to the first insulating material being thermally connected to the first insulating material via the second insulating material, and the first terminal and the second terminal of the metal substrate being provided on the opposite side of the first insulating material." From this description, it is not possible to understand how the "first insulating material" and the "second insulating material" are distinguished. In particular, claim 1 merely specifies the positional relationship between the first insulating material and the second insulating material. However, if an insulating material made of a single material is arranged around a metal substrate and the insulating material is arranged on the first metal substrate, and the part of the insulating material near the first metal substrate is called the "first insulating material" and the part around the metal substrate is called the "second insulating material," then even a single insulating material that is indistinguishable from the outside can be said to contain both the "first insulating material" and the "second insulating material" (see also the reason given in "Reason 2 (Inventive Step)" below). However, it is unclear whether a high-voltage application circuit with such a configuration is included in the invention of claim 1. Therefore, the inventions according to claims 1-4 are unclear. Reason 2 (inventive step) ·Claim 1 ·Citations 1-2 ·remarks Cited Document 1 describes an electronic component module 10 comprising a heat sink 6 (corresponding to the "first metal material" of the present invention), connection terminals 3 (corresponding to the "first metal material, I think it's a mistake and should be called the first terminal" of the present invention) that penetrate a lid 4 from an inner space S to the outside, a wiring board 5 that is housed in the inner space S at a distance from the heat sink 6 and has an electronic component 1 (corresponding to the "electrical component" of the present invention) mounted thereon and connected to the connection terminals 3 (corresponding to the "first terminal" and "second terminal" of the present invention), and a resin 7 that is uniformly filled in the inner space S; A wiring board 5 is formed by printing a conductive paste on an insulating substrate (corresponding to the "insulating layer" of the present invention), or by attaching a metal foil, or by depositing and patterning a metal layer, to form a wiring conductor (corresponding to the "second metal material" of the present invention) and a connection pad 1a (corresponding to the "first conductive region" and the "second conductive region" of the present invention), The electronic components are active elements such as power transistors and power supply ICs. It is described that the electronic component 1 passes a large current at a high voltage (particularly, paragraphs

[0027] -

[0032] ,

[0051] and [Fig. 1]). Furthermore, the flat portion of resin 7 in cited document 1 that contacts heat sink 6 corresponds to the "first insulating material," and the portion that covers wiring board 5 corresponds to the "second insulating material" of the present invention (see also "Regarding Reason 1 (Clarity)"). The invention described in Reference 1 differs in that it is unclear whether the first metal material is connected to ground potential, and it is unclear whether the voltage applied to the first conductive region is different from the voltage applied to the second conductive region. The point of grounding the heat dissipation member in the power module was merely a well-known technique prior to the filing of this application, as described, for example, in Reference 2 (see, in particular, paragraphs

[0010] -

[0011] ). Furthermore, as mentioned above, the electronic component in the invention described in Reference 1 is, for example, a power transistor. Considering that the potentials at each terminal of the transistor are different, making the voltage applied to the first conductive region different from the voltage applied to the second conductive region is merely a design matter that a person skilled in the art could have appropriately made. ■■■■■■ As stated in paragraph

[0032] , the wiring board 5 in Cited Document 1 is "formed by printing a conductive paste on this insulating substrate, or by attaching a metal foil, or by depositing and patterning a metal layer, to form wiring conductors and connection pads 1a, thereby forming the wiring board 5." In other words, both the wiring conductor and the connection pad 1a are formed on the insulating substrate (on the side opposite the heat sink 6). This is clear from Figure 1 etc. In contrast to this, the metal substrate (30) of the present invention is provided on the opposite side of the ceramic plate (20) from the first metal material (10). Furthermore, among the components constituting the metal substrate (30), the second metal material (31) is positioned closest to the ceramic plate (20), and the second metal material (31) is thermally connected to the ceramic plate (20) via a portion of the curable insulating resin (40), the insulating layer (32) is positioned on the upper surface of the second metal material (31), and the first conductive region (33) and the second conductive region (34) are positioned on the upper surface of the insulating layer (32). The first terminal (36) and the second terminal (37) are located on the opposite side of the ceramic plate (20). Furthermore, the components constituting the metal substrate (30), except for the first terminal (36) and the second terminal (37), are covered with a curable insulating resin (40). The examiner found that the wiring conductor in the cited document 1 corresponds to the "second metal material" in the present invention, but the "second metal material" in the present invention is located closest to the ceramic plate (20), so the structure of the present invention and the cited document are different. In fact, there is nothing in the cited document 1 that corresponds to the "second metal material" in the present invention. In addition, the first high voltage and the second high voltage in the present invention are Absolute value is 10kV or more Therefore, the above structure is valid. [Effects of the Invention]

[0008] According to the present invention, in a high voltage application circuit, corona discharge can be suppressed between a high potential portion to which a high voltage is applied and a member at ground potential. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view of a high voltage application circuit 1 of this embodiment. [Figure 2] FIG. 2 is a plan view of the high voltage application circuit 1 of this embodiment as seen from above. [Figure 3] FIG. 3 is an explanatory diagram for explaining the potential of the metal substrate 30. As shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view of a high voltage application circuit 2 of a comparative example corresponding to FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] The high-voltage application circuit 1 of this embodiment is used, for example, in a pulse power supply device that supplies a pulsed voltage (pulse voltage) to a plasma processing apparatus. The pulse power supply device converts DC power into AC power using an inverter circuit, then converts it into AC power of a different voltage value using a transformer, rectifies and smooths it using a rectifying and smoothing circuit, and further outputs a high-voltage pulse voltage with an absolute value of about 10 kV using a switching circuit or the like. Furthermore, since the high voltage application circuit 1 is used in areas where a high voltage with an absolute value of about 10 kV is applied (hereinafter referred to as high potential areas), such as rectifying and smoothing circuits and switching circuits, it is necessary to have a structure that can suppress the occurrence of corona discharge.

[0011] Hereinafter, an embodiment of a high voltage application circuit 1 according to the present disclosure will be described in detail with reference to the accompanying FIGS. FIG. 1 is a cross-sectional view of a high voltage application circuit 1 of this embodiment. FIG. 2 is a plan view of the high voltage application circuit 1 of this embodiment as seen from above. As shown in Figures 1 and 2, the high-voltage application circuit 1 includes a heat sink 10, a ceramic plate 20 provided on the upper side of the heat sink 10, a metal substrate 30 provided on the upper side of the ceramic plate 20, and an insulating resin 40 covering the metal substrate 30.

[0012] 2, the insulating resin 40 is shown in a see-through manner to show the insulating layer 32, the first conductive region 33, the second conductive region 34, the electrical component 35, the first terminal 36, and the second terminal 37 inside the metal substrate 30, which would otherwise be invisible. The metal material 31 is not shown because it is hidden by the insulating layer 32, the first conductive region 33, and the second conductive region 34. Also, due to the size of the drawing, only a portion of the insulating layer 32 is shown.

[0013] The heat sink 10 is an example of a "first metal material" and is a metal material for cooling connected to ground potential, and has a flat plate shape. The material of the heat sink 10 is, for example, copper or aluminum, and a material with high thermal conductivity is suitable. The heat sink 10 may be configured so that cooling water can circulate inside.

[0014] The ceramic plate 20 is an example of the "first insulating material" and is a flat plate-shaped member provided on the flat surface of the heat sink 10 (first metal material). Preferably, alumina, silicon nitride, aluminum nitride, etc. are used. The thickness of the ceramic plate 20 in this embodiment is 10 mm. Generally, the thicker the ceramic plate 20, the longer the distance between the heat sink 10 and the metal material 31 of the metal substrate 30 (described later), which works to make it more difficult for corona discharge to occur. However, the thicker the ceramic plate 20, the lower the heat dissipation effect of the heat sink 10, so it is not preferable to make it too thick. As in this embodiment, by using an alumina ceramic plate as the ceramic plate 20 and configuring it to have a thickness of 10 mm, it is possible to obtain a sufficient heat dissipation effect while suppressing corona discharge when a high voltage with an absolute value of 10 kV or more is applied to a component.

[0015] The metal substrate 30 is, for example, a circuit board using a metal base substrate or a metal core substrate, and the use of a metal material in the base or inside of the substrate can improve heat dissipation. Note that, although Fig. 1 shows an example in which a metal base substrate is used as the metal substrate 30, a metal core substrate can also be used.

[0016] As shown in FIG. 1, the metal substrate 30 includes, for example, a metal material 31, an insulating layer 32, a first conductive region 33, a second conductive region 34, an electrical component 35, a first terminal 36, and a second terminal 37.

[0017] The metal material 31 is an example of a "second metal material" and is a metal material for improving heat dissipation. The metal material is, for example, aluminum, copper, or stainless steel. In FIG. 1, the metal material 31 is positioned below the metal substrate 30 as a metal base, but it may be sandwiched between insulating layers like a metal core substrate. The metal material 31 is not electrically connected to other conductors, but is thermally connected to the heat sink 10 via the insulating resin 40 and the ceramic plate 20, so that the heat generated by the electrical component 35 can be effectively dissipated. The thickness of the metal material 31 is about 0.8 to 5.0 mm. In this embodiment, the metal material 31 used is 2 mm thick (made of aluminum or copper). The thermal conductivity and thickness of the metal material 31 are determined taking into consideration the cost, the size of the metal substrate 30, the weight of the mounted object (to prevent warping), and the like. As mentioned above, corona discharge is likely to occur at angular locations, so as shown in FIG. 2, the corners of the metal material 31 and the first conductive region 33 are rounded rather than right angles.

[0018] The insulating layer 32 is an insulating layer formed on the upper part of the metal material 31, and insulates the metal material 31 from the first conductive region 33 and the second conductive region . The insulating layer 32 is thin, having a thickness of about 0.1 mm, but is shown in FIG. 1 as being thicker than it actually is to make it easier to understand.

[0019] The first conductive region 33 is a conductive region to which a first high voltage having an absolute value of 10 kV or more is applied, and is formed by processing the copper foil layer on the surface of the metal substrate 30. A voltage of -10 kV, for example, is applied to this first conductive region 33.

[0020] The second conductive region 34 is a conductive region to which a second high voltage having an absolute value of 10 kV or more is applied, and is formed by processing the copper foil layer on the surface of the metal substrate 30. A voltage of −11.5 kV, for example, is applied to this second conductive region 34.

[0021] The electrical component 35 is an electrical component mounted between the first conductive region 33 and the second conductive region 34. The electrical component 35 is, for example, a diode, a capacitor, an inductor, a switching element, a resistor, a connector with two or more terminals, a jumper, etc. In the above example, a potential of −10 kV is applied to one terminal of the electrical component 35, and a voltage of −11.5 kV is applied to the other terminal. That is, in the above example, a voltage with a potential difference of 1.5 kV is applied across both ends of the electrical component 35.

[0022] The voltage applied across the electrical component 35 (the voltage between the first conductive region 33 and the second conductive region 34) may be a DC voltage, but is usually a voltage whose value changes, such as an AC voltage or a pulse voltage. In this case, the voltage applied across the electrical component 35 changes over time.

[0023] 1 shows only one electrical component 35 for the sake of simplicity, but multiple electrical components 35 may be mounted. Additionally, multiple electrical components 35 connected in series may be mounted between the first conductive region 33 and the second conductive region 34. Furthermore, if the electrical component 35 is, for example, a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), it essentially has three terminals (gate, drain, and source). Therefore, conductive regions other than the first conductive region 33 and the second conductive region 34 are required, but for the sake of simplicity, some of the terminals and conductive regions of the electrical component 35 are omitted in FIG. 1.

[0024] The first terminal 36 is a terminal electrically connected to the first conductive region 33, and can be electrically connected to the outside via this terminal. The second terminal 37 is a terminal electrically connected to the second conductive region 34, and can be electrically connected to the outside via this terminal. Therefore, the first terminal 36 and the second terminal 37 formed on the metal substrate 30 protrude from the insulating resin 40.

[0025] In the following description, the first conductive region 33 to which the first high voltage is applied and a region having the same potential as the first conductive region 33 will be referred to as a first high potential region, and the second conductive region 34 to which the second high voltage is applied and a region having the same potential as the second conductive region 34 will be referred to as a second high potential region.

[0026] The insulating resin 40 is an example of a "second insulating material" that covers the metal substrate 30 except for the first terminal 36 and the second terminal 37, and is made of an insulating material such as silicone. The insulating resin 40 is used to suppress corona discharge from the metal substrate 30 and to enhance heat dissipation, so it is desirable that the insulating resin 40 has high dielectric strength and good thermal conductivity.

[0027] It is known that the dielectric strength of insulating materials such as silicone is greater than the dielectric strength of air, which is 3.0 kV / mm. For example, silicone rubber with a dielectric strength of about 20 to 30 kV / mm is commercially available. Furthermore, the thermal conductivity of the silicone rubber is greater than that of air, 0.0241 W / m K, and is, for example, approximately 0.1 to 5.1 W / m K. Therefore, if the insulating resin 40 is made of an insulating material such as silicone, corona discharge can be suppressed without significantly reducing heat dissipation. As such, various insulating materials such as silicone are commercially available to suit various applications, so it is sufficient to select an appropriate material taking into consideration dielectric strength and thermal conductivity.

[0028] As will be described later, the thickness of insulating resin 40 applied to the bottom surface of the metal plate is thin, about 0.1 mm. Furthermore, it is preferable that the thickness of insulating resin 40 on the side surface of the metal plate be 1 to 2 mm or more. However, in Fig. 1, the thickness is shown differently from the actual thickness for ease of understanding.

[0029] As described above, the voltage applied across both ends of the electrical component 35 (the voltage between the first conductive region 33 and the second conductive region 34) is usually a voltage whose value changes, such as an AC voltage or a pulse voltage. Therefore, in order to suppress corona discharge, not only the dielectric strength but also the relative dielectric constant is important. This will be explained below.

[0030] <Regarding the relative dielectric constant of insulating resin 40> Corona discharge occurs on the path from the metal substrate 30 to the heat sink 10. This path can be considered as a capacitor with the metal material 31 of the metal substrate 30 as one electrode and the heat sink 10 as the other electrode. Furthermore, if the high voltage applied to the electrical component 35 varies in value, such as an AC voltage or pulse voltage, it is desirable for the insulating resin 40 to have a large relative dielectric constant. This is because the larger the relative dielectric constant, the greater the capacitance between the electrodes, and therefore the smaller the impedance to AC. As a result, the electric field strength is weakened (reduced), which works to make it more difficult for corona discharge to occur. Therefore, the relative dielectric constant of the insulating resin 40 must be greater than 1, which is the relative dielectric constant of the atmosphere, and is preferably at least 3 or greater. This reliably weakens the electric field strength and suppresses corona discharge.

[0031] Furthermore, it is preferable that the relative dielectric constant of the insulating resin 40 is approximately the same as that of the ceramic plate 20. This is because if the relative dielectric constant of the insulator (dielectric) on the path from the metal substrate 30 to the heat sink 10 is uniform, the electric field strength on the path changes linearly, which acts to make it more difficult for corona discharge to occur. However, while the relative dielectric constant of alumina, silicon nitride, aluminum nitride, etc. used for the ceramic plate 20 is approximately 8 to 10, the relative dielectric constant of silicone, etc. used for the insulating resin 40 is at most approximately 6, making it difficult to make the relative dielectric constants of the two the same. Therefore, the insulating resin 40 must be selected while allowing for a certain degree of difference in relative dielectric constant. In light of this situation, it is preferable that the relative dielectric constant of the insulating resin 40 be 6 or higher. In this case, the difference between the relative dielectric constant of the ceramic plate 20 and the relative dielectric constant of the insulating resin 40 is 2 to 4. This makes it easier to suppress the occurrence of corona discharge.

[0032] <Regarding the potential of the metal substrate 30> As described above, the metal material 31 is at a high potential even though it is not electrically connected to other conductors. The reason for this will be explained with reference to FIG. FIG. 3 is an explanatory diagram for explaining the potential of the metal substrate 30. As shown in FIG. Because the first conductive region 33, the second conductive region 34, and the heat sink 10 are conductors, the capacitor 50 can be considered to have the first conductive region 33 and the second conductive region as one electrode and the heat sink 10 as the other electrode. Strictly speaking, a voltage of -10 kV, for example, is applied to the first conductive region 33, and a voltage of -11.5 kV, for example, is applied to the second conductive region 34, so there are two types of capacitors; however, for the sake of simplicity, it is assumed here that a voltage of -10 kV is applied to one electrode of the capacitor 50, and the other electrode is at ground potential.

[0033] Because of the above relationship, the metal material 31 becomes a floating electrode between the one electrode and the other electrode. Therefore, as shown in Fig. 3, the capacitor 50 can be considered as a first capacitor 51 and a second capacitor 52 connected in series. In this case, the dielectric between the electrodes of the first capacitor 51 is the insulating layer 32. The dielectric between the electrodes of the second capacitor 52 is the insulating resin 40 and the ceramic plate 20. However, the thickness (approximately 0.1 mm) of insulating resin 40 applied to the bottom surface of metal material 31 is much thinner than the thickness (10 mm) of ceramic plate 20. Also, the relative dielectric constant of insulating resin 40 and the relative dielectric constant of ceramic plate 20 are not the same, but are not significantly different. Therefore, for the sake of simplicity, the following description will be given assuming that the dielectric between the electrodes of second capacitor 52 is ceramic plate 20.

[0034] Here, the capacitance of the first capacitor 51 is C51=ε0·ε r51 ·S 51 / d 51 year, The capacitance of the second capacitor 52 is C52 = ε0 ε r52 ·S 52 / d 52 Let's say. where ε0 is the dielectric constant of a vacuum, ε r51 is the relative permittivity of the insulating layer 32, S 51 is the electrode area of ​​the first capacitor 51, d 51 is the distance between the electrodes of the first capacitor 51, ε r52 is the relative permittivity of the ceramic plate 20, S 52 is the electrode area of ​​the second capacitor 52, d 52 is the thickness of the ceramic plate 20 (10 mm).

[0035] For the sake of simplicity, the relative dielectric constant ε of the insulating layer 32 is r51 and the relative dielectric constant ε of the ceramic plate 20 r52 and the electrode area of ​​the first capacitor 51 and the electrode area of ​​the second capacitor 52 are the same. Under these assumptions, C51:C52 = 100:1. That is, the capacitance C51 of the first capacitor 51 is 100 times the capacitance C52 of the second capacitor 52. Therefore, in terms of AC, the impedance of the first capacitor 51 is 1 / 100 of the impedance of the second capacitor 52. Furthermore, the voltage applied to the first capacitor 51 is 1 / 100 of the voltage applied to the second capacitor 52. Therefore, the potential of the metal material 31 serving as the floating electrode is approximately −10 kV, which is almost the same as that of the first conductive region 33 and the second conductive region 34. Therefore, corona discharge is likely to occur on the metal material 31 (especially at the corners).

[0036] <Method of forming insulating resin 40> Next, a method for forming the insulating resin 40 will be described. (Step 1) The insulating resin 40 is applied to the bottom surface of the metal substrate 30 (the surface close to the ceramic plate 20). (Step 2) The metal substrate 30 is fixed to the ceramic plate 20, and a mold is fixed around the metal substrate 30. The mold is slightly larger than the metal substrate 30, so the metal substrate 30 fits into the mold. (Step 3) The mold is filled with insulating resin 40, which is then cured. (Step 4) The mold is removed, leaving the metal substrate 30 covered with the insulating resin 40. (Step 5) The insulating resin 40 is removed from the locations of the first terminal 36 and the second terminal 37, and the first terminal 36 and the second terminal 37 are attached. By carrying out the above steps, the metal substrate 30 can be covered with the insulating resin 40 except for the first terminal 36 and the second terminal 37.

[0037] In order to improve heat dissipation from the bottom surface of the metal substrate 30, the thermal conductivity of the insulating resin 40 is preferably 0.3 W / m·K or more. In addition, the viscosity of the insulating resin 40 is preferably 10 Pa·s or less so that it can be applied thinly.

[0038] Furthermore, since corona discharge is likely to occur on the side surfaces of metal substrate 30 (particularly the corners of metal material 31 and first conductive region 33), it is preferable that insulating resin 40 have a thickness of 1 to 2 mm or more.

[0039] <Effects of Providing Insulating Resin 40> Next, the effect of providing the insulating resin 40 will be further explained by comparing with a comparative example shown in FIG. Fig. 4 is a cross-sectional view of a high-voltage application circuit 2 of a comparative example corresponding to Fig. 1, which does not include insulating resin 40 as compared to the high-voltage application circuit 1 shown in Fig. 1. Note that, since the configuration is the same as in Fig. 1 except for insulating resin 40, the same reference numerals as in Fig. 1 are used.

[0040] 4 does not include insulating resin 40, so corona discharge is likely to occur. Corona discharge is particularly likely to occur in the area surrounded by the dotted line, i.e., the corners of metal material 31. It is believed that corona discharge is also likely to occur at the corners of first conductive region 33. However, in this embodiment, the metal substrate 30 is covered with the insulating resin 40 except for the first terminal 36 and the second terminal 37, making it difficult for corona discharge to occur. This is because the dielectric strength of the insulating resin 40 is greater than that of air. Furthermore, because the relative permittivity of the insulating resin 40 is sufficiently greater than that of air, even when the high voltage applied to the electrical component 35 or the like varies in voltage value, such as an AC voltage or a pulse voltage, the electric field strength at the high potential portions (first high potential portion and second high potential portion) can be weakened (reduced). This makes it difficult for corona discharge to occur. In other words, corona discharge can be suppressed.

[0041] The suppression of corona discharge will now be described in more detail. Assuming that the location where corona discharge occurs is the corner of the metal material 31 of the metal substrate 30, the path from the corner of the metal material 31 to the heat sink 10 is compared between the comparative example and this embodiment as follows. (1) Comparative Example: Corner of Metal Material 31 → Air Layer → Ceramic Plate 20 → Heat Sink 10 (2) This embodiment: Corner of metal material 31 → insulating resin 40 → ceramic plate 20 → heat sink 10

[0042] In this way, the area that was an air layer in the comparative example is the insulating resin 40 with a high dielectric strength in this embodiment, so that corona discharge is less likely to occur than in the comparative example. Furthermore, since the first terminal 36 and the second terminal 37 of the metal substrate 30 are provided on the opposite side of the ceramic plate 20, the distance from the first terminal 36 and the second terminal 37 to the heat sink 10 can be made physically long. This makes it difficult for corona discharge to occur from the first terminal 36 and the second terminal 37. Therefore, by configuring the high voltage application circuit 1 as in this embodiment, corona discharge can be suppressed between high potential areas with an absolute value of 10 kV or more (especially corners of the metal material 31 or corners of the first conductive region 33, etc.) and the heat sink 10.

[0043] Furthermore, the metal substrate 30 is provided on the opposite side of the ceramic plate 20 from the heat sink 10, and is thermally connected to the ceramic plate 20 via the insulating resin 40. This allows the heat generated by the metal substrate 30 to be effectively dissipated. That is, in this embodiment, not only is corona discharge suppressed, but measures can also be taken to dissipate heat.

[0044] <Other> (1) An oil compound may be applied between the heat sink 10 and the ceramic plate 20. This increases the adhesion between the heat sink 10 and the ceramic plate 20, thereby improving the heat dissipation effect of the heat generated in the metal substrate. (2) In the embodiment shown in FIGS. 1 and 2, the first high potential region (e.g., −10 kV) is disposed on the outside of the metal substrate 30, and the second high potential region (e.g., −11.5 kV) is disposed at the center of the metal substrate 30. However, this is not limiting, and the first high potential region may be disposed at the center of the metal substrate 30, and the second high potential region may be disposed on the outside of the metal substrate 30. However, as explained in FIG. 4, corona discharge is more likely to occur on the outside of the metal substrate 30, so it is preferable to dispose the first high potential region, which has a lower potential, on the outside. (3) In the above-described embodiment, the first high potential portion and the second high potential portion have a negative (minus) potential, but they may also have a positive (plus) potential.

[0045] Although the embodiments of the present disclosure have been described above, the above-described embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied 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 modifications thereof are included within the scope and spirit of the invention, and are also included in the inventions and their equivalents as defined in the claims.

[0046] Furthermore, the effects of the embodiments described in this specification are merely examples and are not limiting, and other effects may also be obtained. [Explanation of symbols]

[0047] 1 High voltage application circuit 1 10 Heatsink 20 Ceramic plate 30 Metal Substrate 40 Insulating resin 31 Metal materials 32 Insulating layer 33 1st conductive region 34 Second conductive area 35 Electrical Components 36 1st terminal 37 2nd terminal

Claims

1. a first metal member having a plane connected to a ground potential; a flat ceramic plate provided on a plane of the first metal material; a metal substrate having a second metal material, an insulating layer, a first conductive region to which a first high voltage having an absolute value of 10 kV or more is applied, and a second conductive region to which a second high voltage different from the first high voltage and having an absolute value of 10 kV or more is applied, and an electrical component is mounted between the first conductive region and the second conductive region, and a first terminal electrically connected to the first conductive region and a second terminal electrically connected to the second conductive region are formed; a curable insulating resin covering the metal substrate except for the first terminal and the second terminal, the metal substrate is provided on a side of the ceramic plate opposite to the first metal material, Among the members constituting the metal substrate, the second metal material is disposed at a position closest to the ceramic plate, the second metal material is thermally connected to the ceramic plate via a part of the curable insulating resin; the insulating layer is disposed on an upper surface of the second metal material, the first conductive region and the second conductive region are disposed on an upper surface of the insulating layer; the first terminal and the second terminal are provided on the opposite side to the ceramic plate; High voltage application circuit.

2. The curable insulating resin has a relative dielectric constant of 3 or more. The high voltage application circuit according to claim 1 .

3. An oil compound is applied between the first metal material and the ceramic plate.

3. The high voltage application circuit according to claim 1 or 2.

Images