substrate structure

Abstract

Multiple switching devices are electrically connected in parallel using wire bonding or similar methods, resulting in a complex connection structure. [Solution] In a parallel switching unit 10A in which multiple switching devices 10 of a substrate structure 1 are electrically connected in parallel, the package portions 11 of each switching device 10 are arranged side by side on the substrate 20, and the first terminal 15A and second terminal 15C of each switching device 10 extend from the end face 11a of the package portion 11 in the same extending direction D. Each first terminal 15A is electrically connected to a first pattern 42A perpendicular to the extending direction D, and each second terminal 15C extends from the end face 11a of the package portion 11 across the first pattern 42A and is connected to a second pattern 47A which is further away than the first pattern 42A.

Description

Technical Field

[0001] The present invention relates to a board structure including a board having a switching device mounted on a mounting surface thereof.

Background Art

[0002] As a technique of this type, for example, Patent Document 1 discloses a board structure including a board on which a switching device is mounted on a mounting surface. This board structure includes a parallel switching unit in which a plurality of switching devices are electrically connected in parallel. Each switching device has a plurality of lead terminals connected to a plurality of conductor patterns of the board, and the respective conductor patterns to which the lead terminals of each switching device are connected are connected by wires.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] However, in the board structure disclosed in Patent Document 1, when the switching devices are mounted on the board, the lead terminals of the switching devices are soldered to the board, and then when the plurality of switching devices are electrically connected in parallel, the connection is made by wires through wire bonding or the like, which results in a complicated structure.

[0005] The present invention has been made in view of the above points, and an object of the present invention is to provide a board structure capable of electrically connecting a plurality of switching devices in parallel with a simple structure.

Means for Solving the Problem

[0006] In view of the above problems, the substrate structure according to the present invention is a substrate structure including a substrate on which a plurality of switching devices are mounted on a mounting surface. Each switching device comprises a chip-shaped package portion in which a switching element is sealed with resin, and a plurality of lead terminals extending from the end face of the package portion and soldered to a conductive pattern on the substrate. The plurality of lead terminals include a first terminal and a second terminal. The substrate structure comprises a parallel switching unit in which the plurality of switching devices are electrically connected in parallel. In the parallel switching unit, with the package portions of each switching device arranged side by side on the substrate, the first terminal and the second terminal of each switching device extend from the end face of the package portion in the same extending direction. The first terminal of each switching device is electrically connected to a first pattern of the conductive pattern that extends along a direction perpendicular to the extending direction. The second terminal of each switching device extends from the end face of the package portion across the first pattern and is connected to a second pattern of the conductive pattern that is further away from the first pattern.

[0007] According to the present invention, the first terminal of each switching device constituting the parallel switching unit is electrically connected to a first pattern of the conductive pattern that extends in a direction perpendicular to the extension direction. The second terminal of each switching device constituting the parallel switching unit extends from the end face of each package portion, across the first pattern, and is connected to the second pattern. This allows the first pattern connected to the first terminal and the second terminal to intersect three-dimensionally. As a result, multiple switching devices can be electrically connected in parallel with a simple structure without using wires or the like, and the substrate structure can be made more compact.

[0008] In a more preferred embodiment, each switching device has the third terminal formed along the surface of the package portion facing the substrate, and the third terminal formed on each switching device is electrically connected to the third pattern of the conductive pattern.

[0009] According to this embodiment, by electrically connecting the third terminal formed on the surface of the package portion facing the substrate to the third pattern, the pattern shape of the conductor pattern can be made simpler compared to the case where the third terminal is a lead terminal, and the substrate structure can be made more compact.

[0010] In a more preferred embodiment, the substrate structure has a plurality of parallel switching units mounted in the same orientation, and adjacent parallel switching units are electrically connected in series by forming a first pattern connected to one of the parallel switching units and a third pattern connected to the other parallel switching unit in succession.

[0011] According to this embodiment, the first terminal of one parallel switching unit connected to the first pattern and the third terminal of the other parallel switching unit connected to the third pattern formed continuously with the first pattern can be electrically connected. This allows one parallel switching unit and the other to be electrically connected in series via the first and third patterns, for example, using switching devices of the same shape, with a simpler connection structure, compared to when parallel switching units are connected in series using only lead terminals and conductive patterns.

[0012] In a more preferred embodiment, the switching element is a transistor, the second terminal is a control terminal that controls the ON / OFF state of the transistor, and when the transistor is OFF, the potential of the first terminal is lower than the potential of the third terminal.

[0013] In this embodiment, the first terminals (for example, the source terminals in the case of FETs) are connected to the first pattern by a parallel switching unit, and the third terminals (for example, the drain terminals in the case of FETs) are connected to the third pattern by a parallel switching unit, so that multiple transistors can be connected in parallel with a simple structure.

[0014] In a more preferred embodiment, the substrate comprises a substrate body made of a metal material, an insulating layer covering the substrate body, and a conductive layer formed on the insulating layer as the conductive pattern, wherein the conductive layer and the substrate body are electrically insulated by the insulating layer.

[0015] In this embodiment, the conductive layer and the substrate body are electrically insulated by the insulating layer, so the electric field from the conductive layer toward the substrate body depends on the insulating layer. That is, with the insulating layer in between, the conductive layer and the substrate body function as a parallel plate electrode structure, which can mitigate the electric field from the conductive layer and the lead terminals connected thereto toward the surrounding area. As a result, the electric field from the lead terminals toward the surrounding area (for example, air) is mitigated, thus reducing the non-uniformity of the electric field strength. Furthermore, heat generated by the switching device, etc., can be transferred to the substrate body for heat dissipation.

[0016] In a more preferred embodiment, the substrate is placed on a metal heat sink via an insulating plate, the heat sink is connected to ground, and the substrate body of the substrate and the heat sink are electrically insulated via the insulating plate.

[0017] In this embodiment, the conductive layer and the substrate body are electrically insulated by an insulating layer between them, so the conductive layer and the substrate body function as a first capacitor with parallel plate electrodes. On the other hand, the substrate body and the heat sink are electrically insulated by an insulating plate between them, so the substrate body and the heat sink function as a second capacitor with parallel plate electrodes. In this case, the potential of the substrate body becomes a floating potential.

[0018] Here, since the thickness of the insulating layer is sufficiently thinner than the thickness of the insulating board, when the capacitance of the first capacitor is C1 and the capacitance of the second capacitor is C2, C1 >> C2. Therefore, the voltage applied to the first capacitor is significantly smaller than the voltage applied to the second capacitor. Consequently, the potential difference between the potential of the conductive layer and the lead terminals connected thereto and the potential of the substrate body is relatively small. As a result, the structure suppresses discharge from the lead terminals toward the substrate body.

[0019] In a more preferred embodiment, the substrate structure further includes connection terminals connected to the third pattern of one parallel switching unit and connection terminals connected to the first pattern of the other parallel switching unit. According to this embodiment, by selecting the number of parallel and series substrate structures and connecting the connection terminals between the substrate structures in accordance with this selection, an electrical circuit can be easily configured according to the usage conditions.

[0020] In a more preferred embodiment, at least the plurality of lead terminals are sealed with an insulating molding material. In this embodiment, when the conductive layer (conductive pattern) and the lead terminals are soldered together, a gap (air layer) is formed between the conductive layer and the lead terminals. However, by sealing at least the lead terminals with an insulating molding material, the molding material is filled into the gap between the conductive layer and the lead terminals, thereby suppressing the occurrence of corona discharge in the gap between the conductive layer and the lead terminals. [Effects of the Invention]

[0021] According to the present invention, multiple switching devices can be electrically connected in parallel with a simple structure. [Brief explanation of the drawing]

[0022] [Figure 1] This is a schematic perspective view of a substrate structure according to an embodiment of the present invention. [Figure 2]This is a schematic perspective view of the substrate structure shown in Figure 1 viewed from another direction. [Figure 3] (a) is a plan view of the substrate structure shown in Figure 1, and (b) is a plan view showing the conductive pattern of the substrate. [Figure 4] This is an electrical circuit diagram of the substrate structure shown in Figure 1. [Figure 5] (a) is a schematic perspective view of the switching device mounted on the substrate shown in Figure 1 as viewed from the front side, and (b) is a schematic perspective view of the switching device shown in (a) as viewed from the back side. [Figure 6] This is a cross-sectional view of the substrate structure along the line A-A shown in Figure 3(a) in the arrow viewing direction. [Mode for Carrying Out the Invention]

[0023] Hereinafter, the substrate structure according to the present invention will be described with reference to Figures 1 to 6. The substrate structure 1 according to the present embodiment is a high-voltage substrate structure including a substrate 20 on which a switching device 10 is mounted on a mounting surface 20a. For convenience of description, the insulating plate 61 and the heat dissipation plate 62 shown in Figure 6 are omitted in Figures 1 and 2.

[0024] In the present embodiment, the switching device 10 is a semiconductor device including a high-voltage semiconductor switching element (switching element 12, see, for example, Figure 6) such as an FET (Field Effect Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor).

[0025] In the present embodiment, as shown in Figure 1, in the substrate structure 1, a plurality of (for example, four) switching devices 10 are mounted on the mounting surface 20a of the substrate 20. Specifically, as shown in the electrical circuit diagram of Figure 4, the substrate structure 1 includes a plurality of (for example, two) parallel switching units 10A and 10B in which a plurality of (for example, two) switching devices 10 are electrically connected in parallel. The plurality of parallel switching units 10A and 10B are electrically connected in series to each other.

[0026] Each switching device 10 includes a chip-shaped package portion 11 in which a switching element 12 is sealed with resin 13, as shown in Figure 6, which will be described later. In this embodiment, the switching device 10 is positioned such that one of the two surfaces 11b, 11c of the package portion 11 (see, for example, Figures 5(b) and 6) faces the mounting surface 20a of the substrate 20. In other words, the switching device 10 is positioned on the mounting surface 20a of the substrate 20 with the package portion 11 tilted (lying down) toward the mounting surface 20a.

[0027] A mounting hole 16 with a circular opening is formed in the center of the package portion 11 of the switching device 10. Normally, the package portion 11 of the switching device 10 may be attached to the substrate 20 by inserting a fastener or the like into the mounting hole 16. However, in this embodiment, in order to avoid discharge from the fastener inserted into the mounting hole 16, the drain electrode 15D of the package portion 11, which will be described later, is electrically connected to the conductive pattern 40 (specifically, the third pattern 41) via solder, thereby fixing the package portion 11 to the substrate 20 without using the mounting hole 16.

[0028] Each switching device 10 further includes a plurality (for example, three) of lead terminals 15 (15A to 15C) that extend in the same direction (extension direction D) from the end face of the package portion 11 and are soldered to the conductive pattern 40 of the substrate 20 (see Figure 3). As shown in Figure 6, which will be described later, within the package portion 11, each lead terminal 15 is connected to the switching element 12 via a wire 15F by wire bonding or the like. In this connected state, the switching element 12 is sealed (packaged) with resin 13. The lead terminals 15 (15A to 15C) are pin-shaped terminals with a rectangular cross-section and extend from the end face 11a of the package portion 11.

[0029] In this embodiment, the lead terminal 15 of the switching device 10 includes three terminals: a main current source terminal 15A, a gate source terminal 15B, and a gate terminal 15C. The main current source terminal 15A is shorter in length than the gate source terminal 15B and the gate terminal 15C. Furthermore, of the two surfaces 11b and 11c of the package portion 11 of the switching device 10, a drain electrode 15D is formed along the surface 11c (see, for example, Figures 5(b) and 6).

[0030] In this invention, the "first terminal" corresponds to the main current source terminal 15A. In this invention, the "second terminal" corresponds to the gate terminal 15C and is a control terminal that controls the ON / OFF state of the switching element 12 (transistor). In this invention, the "third terminal" corresponds to the drain electrode 15D. As shown in Figure 4, when the switching element 12 is OFF, the potential of the main current source terminal (first terminal) 15A is connected to be lower than the potential of the drain electrode (third terminal) 15D.

[0031] As shown in Figures 1 and 2, each parallel switching unit 10A (10B) has its package portion 11 of each switching device 10 arranged side by side on the mounting surface 20a of the substrate 20, with the lead terminals 15 (15A to 15C) of each switching device 10 extending from the end face 11a of the package portion 11 in the same extension direction D. Multiple such parallel switching units 10A and 10B are mounted on the mounting surface 20a of the substrate 20 in the same orientation.

[0032] As shown in Figure 3(b), a conductive pattern 40 is formed on the mounting surface 20a of the substrate 20. The conductive pattern 40 has a first pattern 42 (42A, 42B). The first pattern 42 (42A, 42B) is a pattern that extends in a direction perpendicular to the extending direction D of the lead terminals 15 (15A~15C) when the switching device 10 is mounted (orthogonal direction T). The first patterns 42A and 42B are provided for each parallel switching unit 10A, 10B. The main current source terminal (first terminal) 15A of each parallel switching unit 10A (10B) is electrically connected by solder or the like.

[0033] The conductive pattern 40 has multiple (specifically four) second patterns 47 (47A, 47B). The number of second patterns 47 corresponds to the number of switching devices 10, and one pattern is provided for each switching device 10. The second patterns 47 (47A, 47B) are formed at a position further away from the switching devices 10 than the first patterns 42 (42A, 42B). The second patterns 47 (47A, 47B) are linear wiring patterns.

[0034] The conductive pattern 40 has a separate wiring pattern 46 (46A, 46B) connected to the gate source terminal 15B, spaced apart from each of the second patterns 47 (47A, 47B). The first pattern 42 (42A, 42B), the second pattern 47 (47A, 47B), and the wiring pattern 46 (46A, 46B) are each electrically independent patterns. The gate terminal (second terminal) 15C of each switching device 10 extends from the end face 11a of the package portion 11, across the first pattern 42 (42A, 42B), and is connected to the second pattern 47 (47A, 47B). Similarly, the gate source terminal 15B of each switching device 10 extends from the end face 11a of the package portion 11, across the first pattern 42 (42A, 42B), and is connected to the wiring pattern 46 (46A, 46B).

[0035] In this way, the main current source terminal (first terminal) 15A of each switching device 10 constituting the parallel switching unit 10A (10B) is electrically connected to the first pattern 42A (42B) which extends in a direction perpendicular to the extending direction D. The gate source terminal 15B and gate terminal (second terminal) 15C of each switching device 10 constituting the parallel switching unit 10A (10B) extend from the end face 11a of each package portion 11, across the first pattern 42, and are connected to the second pattern 47A (47B) and wiring pattern 46A (46B), respectively. This allows the first pattern 42A (42B) connected to the main current source terminal (first terminal) 15A and the gate source terminal 15B and gate terminal (second terminal) 15C to intersect three-dimensionally. As a result, multiple switching devices 10, 10 can be electrically connected in parallel with a simple structure without using wires, and the substrate structure 1 can be made more compact.

[0036] In this embodiment, the substrate 20 is equipped with double-stacked terminals 32A and 32B. In this embodiment, other electrical or electronic components may be mounted on the substrate 20. One end of the second pattern 47A (47B) is electrically connected to the gate terminal (second terminal) 15C of the switching device 10 constituting the parallel switching unit 10A (10B), and the other end of the second pattern 47 (47B) is electrically connected to the double-stacked terminal 32A (32B). Similarly, one end of the wiring pattern 46A (46B) is electrically connected to the gate source terminal 15B of the switching device 10 constituting the parallel switching unit 10A (10B), and the other end of the wiring pattern 46A (46B) is electrically connected to the double-stacked terminal 32A (32B).

[0037] The conductive pattern 40 has multiple (specifically two) third patterns 41 (41A, 41B). The number of third patterns 41 corresponds to the number of parallel switching units 10A and 10B, and is provided for each parallel switching unit 10A and 10B. Each third pattern 41A (41B) is electrically connected to the drain electrode (third terminal) 15D formed on each of the switching devices 10.

[0038] In this way, by connecting the main current source terminals (first terminals) 15A of each switching device 10 in each parallel switching unit 10A (10B) to the first pattern 42A (42B), and connecting the drain electrode (third terminal) 15D to the third pattern 41A (41B), the switching elements 12 can be connected in parallel with a simple structure. As a result, the two switching devices 10, 10 of each parallel switching unit 10A (10B) can be electrically connected in parallel with a simpler pattern shape for the conductive pattern 40 compared to the case where the third terminal is a lead terminal. As a result, the substrate structure 1 can be made more compact.

[0039] Furthermore, in this embodiment, the substrate 20 is equipped with three block terminals 31 (31A to 31C). Each block terminal 31 (31A to 31C) is columnar, and the boundaries between the sides of the block terminals 31 are also rounded. The conductive pattern 40 has rectangular connection patterns 43 (43A to 43C) that electrically connect each block terminal 31. In this embodiment, adjacent parallel switching units 10A and 10B are electrically connected in series by forming a first pattern 42A connected to one parallel switching unit 10A and a third pattern 41B connected to the other parallel switching unit 10B, continuously via a connection pattern 43B. The connection pattern 43A is formed continuously with the first pattern 42A connected to one parallel switching unit 10A. The connection pattern 43C is formed continuously with the first pattern 42B connected to the other parallel switching unit 10B. In this way, the substrate structure 1 can obtain the electrical circuit shown in Figure 4 without using wires or the like.

[0040] In this way, the main current source terminal (first terminal) 15A of one parallel switching unit 10A, which is connected to the first pattern 42A, and the drain electrode (third terminal) 15D of the other parallel switching unit 10B, which is connected to the third pattern 41B formed continuously with the first pattern 42A, can be electrically connected. This allows one parallel switching unit 10A and the other parallel switching unit 10B to be electrically connected in series with a simple connection structure, for example, using a switching device 10 of the same shape, via the first pattern 42A and the third pattern 41B. In addition, a voltage from a power supply (not shown) can be applied between the block terminal 31A erected on the connection pattern 43A and the block terminal 31C erected on the connection pattern 43C. In this way, an electrical circuit can be configured with two switching devices 10 in parallel and two in series. The block terminal 31B is connected to connection pattern 43B, which is the connection point between one parallel switching unit 10A and the other parallel switching unit 10B.

[0041] As described above, the substrate structure 1 of this embodiment can constitute the electrical circuit shown in Figure 4. Therefore, the voltage applied between block terminal 31A (the terminal connected to the drain electrode 15D) and block terminal 31C (the terminal connected to the main current source terminal 15A) can be shared and borne by each component. In the substrate structure 1 of this embodiment, an electrical circuit can be configured with two switching devices 10 in parallel and two in series, so each switching device 10 will bear half of the voltage applied between block terminal 31A and block terminal 31C.

[0042] Furthermore, since the switching devices 10 are connected in parallel, the current flowing through each switching device 10 can be halved, making it suitable for high-current applications. Block terminals 31A and 31C are examples of the "connection terminals" of the present invention.

[0043] Furthermore, multiple board structures 1 of this embodiment can be easily connected and used. For example, by connecting the block terminal 31C of the first board structure 1 to the block terminal 31A of the second board structure 1, an electrical circuit can be configured with 2 switching devices 10 in parallel and 4 in series. Also, by connecting the block terminal 31C of the second board structure 1 (the terminal connected to the main current source terminal 15A) to the block terminal 31A of the third board structure 1 (the terminal connected to the drain electrode 15D), an electrical circuit can be configured with 2 switching devices 10 in parallel and 6 in series. Similarly, by using four board structures 1, an electrical circuit can be configured with 2 switching devices 10 in parallel and 8 in series. As can be seen from the above, the number of series connections can be increased by 2 each time the number of board structures 1 is increased.

[0044] Furthermore, by connecting the block terminals 31A of the two board structures 1 and the block terminals 31C of the two board structures 1, an electrical circuit can be configured with 4 switching devices 10 in parallel and 2 in series. Using the same approach as above, by increasing the number of series connections of the 4 parallel and 2 series switching devices 10, electrical circuits such as 4 parallel and 4 series, 4 parallel and 6 series, 4 parallel and 8 series, etc., can be configured.

[0045] Using a similar approach, by connecting the block terminals 31A of the three board structures 1 and the block terminals 31C of the three board structures 1, an electrical circuit can be constructed with 6 switching devices 10 in parallel and 2 in series. Furthermore, the number of series connections can be increased. In other words, by selecting the number of parallel and series connections of the substrate structure 1, an electrical circuit can be easily configured according to the usage conditions.

[0046] Therefore, the substrate structure 1 of this embodiment can be suitably used in, for example, high-voltage inverter devices with an operating voltage of several kV to tens of kV (for example, 10 kV or more). For example, even if the electrical circuit of the substrate structure 1 is the electrical circuit shown in Figure 4, and the voltage withstand capability of the switching device 10 is around 1,500V, if four substrate structures 1 are connected in series, the voltage withstand capability of one switching device 10 will be 1 / 8 of the total, so even if the voltage (absolute value) applied to the inverter device is 10kV, there will be no voltage withstand capability problem.

[0047] Even if the operating voltage is shared among the switching devices 10, there will still be some switching devices 10 with large potential differences between them and ground, so it is conceivable that some of the switching devices 10 may discharge from their leads. For this reason, the following configuration is adopted in this embodiment.

[0048] In this embodiment, as shown in Figures 1, 5(a), (b), and 6, each lead terminal 15 (15A to 15C) of the switching device 10 includes a base portion 15a extending from the package portion 11 along the mounting surface 20a, and a first bent portion 15b that is continuous with the base portion 15a and bent at an obtuse angle toward the mounting surface 20a.

[0049] Furthermore, each lead terminal 15 (15A to 15C) extends from the first bent portion 15b toward the mounting surface 20a and includes an inclined portion 15c that is inclined with respect to the mounting surface 20a, and a second bent portion 15d that is continuous with the inclined portion 15c and is bent at an obtuse angle toward the mounting surface 20a.

[0050] Furthermore, each lead terminal 15 (15A to 15B) extends from the second bent portion 15d of the switching device 10 toward the mounting surface 20a and includes a tip portion 15e connected to the first pattern 42 (42A, 42B), the second pattern 47 (47A, 47B), etc.

[0051] More specifically, as shown in Figure 6, the base portion 15a extends along the first imaginary line L1, the inclined portion 15c extends along the second imaginary line L2, and the tip portion 15e extends along the third imaginary line L3. A first bent portion 15b exists so as to include the point where the first imaginary line L1 and the second imaginary line L2 intersect. A second bent portion 15d exists so as to include the point where the second imaginary line L2 and the third imaginary line L3 intersect.

[0052] Here, the bending angle of the first bent portion 15b is an obtuse angle formed by the first imaginary line L1 and the second imaginary line L2, and for example, this angle is preferably in the range of 120° to 150°. On the other hand, the bending angle of the second bent portion 15d is an angle formed by the second imaginary line L2 and the third imaginary line L3, and this angle is also an obtuse angle, and this angle is also preferably in the range of 120° to 150°.

[0053] The bending angle of the first bent portion 15b and the bending angle of the second bent portion 15d may be the same, but in this embodiment, the bending angle (size of the obtuse angle) of the first bent portion 15b is smaller than the bending angle (size of the obtuse angle) of the second bent portion 15d. In this embodiment, the bending angle of the first bent portion 15b is, for example, about 135°, and the bending angle of the second bent portion 15d is about 140°.

[0054] By satisfying this angular relationship, the tip portion 15e of each lead terminal 15 (15A to 15C) can be extended toward the first pattern 42 (42A, 42B), the second pattern 47 (47A, 47B), and the wiring pattern 46 (46A, 46B). As a result, the lead terminals 15 can be stably joined to each of the first pattern 42 (42A, 42B), the second pattern 47 (47A, 47B), and the wiring pattern 46 (46A, 46B) of the substrate 20 by soldering.

[0055] In this embodiment, the difference in length between lead terminal 15A and lead terminals 15B and 15C depends on the difference in the length of the base portion 15a. That is, in this embodiment, lead terminals 15A to 15C have the same shape from the first bent portion 15b to the tip portion 15e, and lead terminal 15A differs from lead terminals 15B and 15C only in the length of the base portion 15a.

[0056] In this way, by adjusting only the length of the base portion 15a, each tip portion 15e of the lead terminal 15 (15A to 15C) can be soldered to the first pattern 42 (42A, 42B), the second pattern 47 (47A, 47B), and the wiring pattern 46 (46A, 46B) in a fixed orientation. This improves the reliability of the solder joint and allows the lead terminal 15 (15A to 15C) to be stably sealed with the molding material 50 described later.

[0057] In this embodiment, the substrate 20 is a metal substrate comprising a substrate body 21 made of a metal material, an insulating layer 23 covering one side of the substrate body 21, and a conductive layer 24 formed on the insulating layer 23 as a conductive pattern 40 and soldered to the lead terminals 15. The metal material constituting the substrate body 21 is made of copper or aluminum, etc. The insulating layer 23 is made of an insulating material such as epoxy resin or glass epoxy resin formed by solder resist, etc. The conductive layer 24 is a layer made of copper and is composed of a conductive pattern 40. In this embodiment, the conductive layer 24 and the substrate body 21 are electrically insulated by the insulating layer 23.

[0058] Here, the substrate 20 (substrate body 21) may be fixed to another component via the fixing holes 25 in a floating state (specifically, in a state where the potential of the surface of the substrate body 21 is floating). However, in this embodiment, the substrate 20 is fixed in contact with the insulating plate 61 (see Figure 6), which will be described later, via the fixing holes 25.

[0059] In this embodiment, as shown in Figure 6, the substrate 20 is placed on a metal heat sink 62 via an insulating plate 61. The substrate body 21 of the substrate 20 and the heat sink 62 are electrically insulated from each other via the insulating plate 61. The insulating plate 61 is not particularly limited as long as it has insulating properties, but in this embodiment, the insulating plate 61 is a ceramic plate, and examples of its material include alumina and aluminum nitride. By using a ceramic plate for the insulating plate 61, the heat generated by the switching device 10, etc., can be transferred from the substrate body 21 of the substrate 20 to the insulating plate 61, which is a ceramic plate, and the heat can be efficiently dissipated from the heat sink 62.

[0060] The heat sink 62 is, for example, a heat sink or a part thereof, and the heat sink is water-cooled or air-cooled, and the heat that enters the heat sink 62 is dissipated. Here, the main body 21 of the substrate 20 may or may not be connected to ground, but in this embodiment, the main body 21 is not connected to ground, and the heat sink 62 is connected to ground.

[0061] Furthermore, as shown in Figure 6, the lead terminals 15 are sealed with insulating molding material 50. In this embodiment, the parts other than the connection portions of the block terminals 31A to 31C and the double-stacked terminals 32A and 32B are sealed with molding material 50.

[0062] For example, silicone resin can be used as the material for the molding material 50. When the conductive layer 24 and the lead terminals 15 (15A~15C) are soldered together, a gap (air layer) is created between them. In this embodiment, by sealing the lead terminals 15 (15A~15C) with the molding material 50, the molding material 50 is also filled into these gaps, thereby suppressing the occurrence of corona discharge in these gaps. The dielectric breakdown field strength of air is 3 kV / mm, while the dielectric breakdown field strength of silicone resin is approximately 20 kV / mm. Therefore, by using silicone resin for the molding material 50, more than six times the corona resistance can be expected compared to when the molding material 50 is not used.

[0063] According to this embodiment, the obtuse-angled first bent portion 15b and second bent portion 15d suppress the concentration of the electric field in the first bent portion 15b and second bent portion 15d compared to lead terminals having bent portions bent at approximately right angles as in the past. As a result, corona discharge from the first bent portion 15b and second bent portion 15d is suppressed, and the generation of ozone caused by corona discharge can be prevented.

[0064] Furthermore, in this embodiment, the conductive layer 24 and the substrate body 21 are electrically insulated by the insulating layer 23 between them, so that the conductive layer 24 and the substrate body 21 function as a first capacitor with parallel plate electrodes.

[0065] Furthermore, in this embodiment, the substrate body 21 and the heat sink 62 of the substrate 20 are electrically insulated by the insulating plate 61 between them, so the substrate body 21 and the heat sink 62 function as a second capacitor with parallel plate electrodes. In this case, the potential of the substrate body 21 becomes a floating potential.

[0066] Here, since the thickness of the insulating layer 23 is sufficiently thinner than the thickness of the insulating plate 61, when the capacitance of the first capacitor is C1 and the capacitance of the second capacitor is C2, C1 >> C2. Therefore, the voltage applied to the first capacitor is significantly smaller than the voltage applied to the second capacitor.

[0067] Therefore, the potential difference between the conductive layer 24 and the lead terminals 15 (15A~15C) connected thereto and the potential of the substrate body 21 is relatively small. As a result, the structure suppresses discharge from the lead terminals 15 to the substrate body 21. Strictly speaking, the relative permittivity of the insulating layer 23 and insulating plate 61, the area of ​​the conductive layer 24, the substrate body 21 and heat sink 62, etc., should be considered, but the explanation is omitted here.

[0068] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above, and various design modifications can be made without departing from the spirit of the invention as described in the claims.

[0069] The switching element 12 may also be an IGBT (Insulated Gate Bipolar Transistor). In this case, the first terminal 15A described above may be the emitter terminal, the second terminal 15C may be the gate terminal, and the third terminal 15D may be the collector terminal. [Explanation of Symbols]

[0070] 1: Substrate structure, 10: Switching device, 10A, 10B: Parallel switching unit, 11: Package portion, 11a: End face, 11c: Surface, 12: Switching element, 13: Resin, 15: Lead terminal, 15A: Main current source terminal (1st terminal, lead terminal), 15B: Gate source terminal (lead terminal), 15C: Gate terminal (2nd terminal, lead terminal), 15D: Dray Electrode (third terminal), 20: substrate, 21: substrate body, 23: insulating layer, 24: conductive layer, 31A, 31B: block terminals (connection terminals), 40: conductive pattern, 41, 41A, 41B: third pattern, 42, 42A, 42B: first pattern, 47, 47A, 47B: second pattern, 47, 47A, 47B: second pattern, 50: molding material, 61: insulating plate, 62: heat sink, D: extension direction

Claims

1. A substrate structure including a substrate on which multiple switching devices are mounted on the mounting surface, Each of the aforementioned switching devices comprises a chip-shaped package portion in which the switching element is sealed with resin, and a plurality of lead terminals extending from the end face of the package portion and soldered to the conductive pattern of the substrate. The plurality of lead terminals include at least a first terminal and a second terminal, The substrate structure comprises a parallel switching unit in which the plurality of switching devices are electrically connected in parallel. The parallel switching unit is configured such that the package portions of each switching device are arranged side by side on the substrate, and the first and second terminals of each switching device extend from the end face of the package portion in the same direction. Each of the switching devices has a first terminal that is electrically connected to a first pattern of the conductive pattern that extends in a direction perpendicular to the extension direction. The substrate structure is characterized in that the second terminal of each switching device extends from the end face of the package portion across the first pattern and is connected to a second conductive pattern that is further away from the first pattern.

2. Each of the switching devices has a third terminal formed along the surface of the package portion that faces the substrate. The substrate structure according to claim 1, characterized in that the third terminal formed on each of the switching devices is electrically connected to the third pattern among the conductive patterns.

3. The aforementioned substrate structure has multiple parallel switching units mounted in the same orientation. The substrate structure according to claim 2, characterized in that adjacent parallel switching units are electrically connected in series by forming a first pattern connected to one of the parallel switching units and a third pattern connected to the other parallel switching unit in a continuous manner.

4. The switching element is a transistor, The substrate structure according to claim 2, characterized in that the second terminal is a control terminal for controlling the ON / OFF state of the transistor, and when the transistor is OFF, the potential of the first terminal is connected to be lower than the potential of the third terminal.

5. The substrate comprises a substrate body made of a metal material, an insulating layer covering the substrate body, and a conductive layer formed on the insulating layer as the conductive pattern. The substrate structure according to claim 1, characterized in that the conductive layer and the substrate body are electrically insulated by the insulating layer.

6. The substrate is placed on a metal heat sink via an insulating plate, and the heat sink is connected to ground. The substrate structure according to claim 5, characterized in that the substrate body of the substrate and the heat sink are electrically insulated from each other via the insulating plate.

7. The substrate structure according to claim 3, further comprising a connection terminal connected to the third pattern of one of the parallel switching units and a connection terminal connected to the first pattern of the other parallel switching unit.

8. The substrate structure according to any one of claims 1 to 7, characterized in that at least the plurality of lead terminals are sealed with an insulating molding material.

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