Power module

Abstract

To solve the problem that it is difficult to remove a component mounting board from an element mounting board and easily replace the component mounting board.SOLUTION: A power module 1 comprises an element mounting board 10, a component mounting board 20, a connector board 30 and a casing 70 for accommodating them, and starting from the bottom of casing 50, the element mounting board 10, the component mounting board 20, and the connector board 30 are connected in a removable manner with spacing provided by a plurality of pillars 50.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a high-voltage power module. [Background technology]

[0002] As one such technique, a power module has been proposed that includes an inverter board (element mounting board) on which at least power semiconductor elements are mounted, and first and second boards on which electrical or electronic components are mounted (see, for example, Patent Document 1). The inverter board, the first board, and the second board are connected at intervals by a source connection terminal and a gate connection terminal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-107876 Summary of the Invention [Problem to be solved by the invention]

[0004] In the power module of Patent Document 1, if, for example, during inspection, it is found that the electronic or electrical components mounted on the first substrate located between the first substrate and the second substrate do not have the desired characteristics, the component mounting substrate corresponding to this first substrate will be replaced. However, because the connection terminals that connect the component mounting substrate to the component mounting substrate are generally connected to the component mounting substrate by soldering or the like, it is not easy to detach the component mounting substrate from the component mounting substrate and replace it.

[0005] The present invention has been made in view of the above points, and has an object to provide a power module in which a component mounting board can be detached from an element mounting board and the component mounting board can be easily replaced. [Means for solving the problem]

[0006] In view of the above problems, a power module according to the present invention is a high-voltage power module, the power module having: an element mounting board on which at least a semiconductor element is mounted on an insulating substrate made of ceramic; a component mounting board on which mounted components of electrical or electronic components electrically connected to the semiconductor element are mounted; and a connector board electrically connected to the mounted components and having a connection portion electrically connected to at least an external device; and a casing that houses the element mounting board, the component mounting board, and the connector board, and the element mounting board, the component mounting board, and the connector board are detachably connected, in this order from the bottom of the casing, by a plurality of supports at intervals.

[0007] According to the present invention, the element mounting board, the component mounting board, and the connector board are detachably connected at intervals by multiple supports, in that order from the bottom of the casing, so that the element mounting board, the component mounting board, and the connector board can be easily separated. In particular, if the characteristics of the electronic or electrical components mounted on the component mounting board do not meet the desired characteristics during inspection, the component mounting board will be replaced. In this embodiment, even if the component mounting board is positioned between the element mounting board and the connector board, the component mounting board can be easily removed from the connector board and the element mounting board, and the component mounting board can be easily replaced.

[0008] In a more preferred embodiment, each of the support pillars is composed of a first support pillar that stands upright from the element mounting board and supports the component mounting board, and a second support pillar that stands upright from the component mounting board and supports the connector board, one of the first support pillar and the second support pillar has a male threaded portion formed at an end, and the other has a female threaded portion formed at an end that screws into the male threaded portion, and the component mounting board is clamped between the first support pillar and the second support pillar by screwing the male threaded portion and the female threaded portion into each other through a through hole formed in the component mounting board.

[0009] According to this aspect, while the component mounting board is sandwiched between the first support pillar and the second support pillar, the male threaded portion and the female threaded portion can be screwed together through the through-holes formed in the component mounting board. This allows the component mounting board to be easily removed from between the device mounting board and the connector board by unscrewing the first support pillar and the second support pillar. Furthermore, by screwing the male threaded portion and the female threaded portion together through the through-holes formed in the component mounting board and tightening the first support pillar and the second support pillar, the component mounting board can be stably fixed to the device mounting board and the connector board.

[0010] In a further preferred embodiment, the end face of the support is exposed from the connector board at a through hole formed in the connector board when viewed in a plane of the connector board, and the support is a connection terminal that is electrically connected to the mounted component or the semiconductor element.

[0011] According to this aspect, the structure of the power module can be simplified by using the support posts as connection terminals electrically connected to the mounted components or semiconductor elements. Since the end faces of the support posts are exposed in the through holes of the connector substrate as end faces of the connection terminals, the end faces can be used as connection parts for connection to external devices, etc.

[0012] In a more preferred embodiment, the component mounting board is rectangular, and an inlet is formed in the center of the component mounting board for introducing a sealing material that seals the component mounting board into the casing.

[0013] According to this aspect, an inlet for introducing the sealant that seals the component mounting board into the casing is formed in the center of the component mounting board, so that the sealant can be stably flowed toward the component mounting board from the inlet of the component mounting board, thereby making it possible to uniformly seal the entire surface of the component mounting board with the sealant while suppressing the formation of air bubbles in the sealant.

[0014] In a further preferred embodiment, the component mounting board is equipped with an optical receiver as one of the mounted components, which is connected to an optical fiber and receives an optical signal from the optical fiber, and the connector board has an opening formed in a position opposite the optical receiver.

[0015] According to this aspect, before guiding the optical fiber to the optical receiver, a jig for discharging the sealant can be inserted using the opening of the connector substrate, and the sealant discharged from the jig can be introduced from the introduction port of the component mounting substrate toward the element mounting substrate. After sealing with the sealant is completed, the optical fiber can be guided from the opening of the connector substrate to the optical receiver, and the optical fiber can be easily connected to the optical receiver.

[0016] In a more preferred embodiment, the semiconductor element is a field effect transistor, and the component mounting board is provided with a gate drive circuit that is composed of some of the multiple mounted components and drives the field effect transistor, and the gate drive circuit controls the waveform of a gate voltage using an optical signal received by the optical receiver as a control signal, and the optical receiver and the gate drive circuit are arranged side by side on one of the two sides of the light introduction port on the component mounting board.

[0017] According to this aspect, by arranging the gate drive circuit and the optical receiver side by side on one of the two sides of the inlet, the optical receiver can be located near the gate drive circuit, and the optical signal received by the optical receiver can be input to the gate drive circuit with high precision, thereby enabling the gate drive circuit to generate with high precision the waveform of the gate voltage that drives the field-effect transistor. [Effects of the Invention]

[0018] According to the present invention, the component mounting board can be easily removed from the element mounting board and the component mounting board can be easily replaced. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic perspective view of a power module according to an embodiment of the present invention; [Figure 2] 2A is a top view of the power module shown in FIG. 1, and FIG. 2B is a bottom view of the power module shown in FIG. [Figure 3] FIG. 2 is a side view of the power module shown in FIG. [Figure 4] FIG. 2 is a perspective view of the substrate structure shown in FIG. [Figure 5] FIG. 2 is an exploded perspective view of the substrate structure shown in FIG. [Figure 6] (A) is an oblique view of a reference voltage connection terminal, (B) is an exploded oblique view of (A), (C) is a cross-sectional view of a component mounting board with a reference voltage connection terminal attached, and (D) is a cross-sectional view of a connector board with a reference voltage connection terminal attached. [Figure 7] FIG. 2A is a schematic perspective view of an insulating substrate on which a conductor pattern is formed and an insulating film, and FIG. 2B is an exploded perspective view of a device mounting substrate. [Figure 8] 1A is a schematic cross-sectional view illustrating a state in which an insulating substrate on which a conductor pattern is formed is covered with an insulating film, and FIG. 1B is a modified example of FIG. [Figure 9] 6 is an exploded perspective view of the substrate structure shown in FIG. 5 as viewed from the other side. DETAILED DESCRIPTION OF THE INVENTION

[0020] 1. Overall structure of power module 1 A power module 1 according to an embodiment of the present invention will be described below with reference to FIGS. 1 to 9. The power module 1 according to this embodiment is a power module for high voltages (for example, an absolute value of several kV to several tens of kV). The power module 1 is a module including semiconductor switching elements such as high-voltage field-effect transistors (FETs), and has a structure that provides good heat dissipation for heat generated by switching and suppresses discharge that tends to occur when a high voltage is applied to the semiconductor switching elements. Note that in this embodiment, the FET module described above is used as an example of the power module 1, but the power module 1 may also be a diode module including high-voltage diodes (semiconductor elements). Even in the case of a diode module, by adopting a structure corresponding to a diode module from among the structures described below, it is possible to improve heat dissipation for heat generated in the diode and suppress discharge that tends to occur when a high voltage is applied to the diode.

[0021] As shown in FIG. 1, the power module 1 includes a plurality of (for example, two) substrate structures 1A and a casing 70 that houses them. As shown in FIGS. 3 and 4, the substrate structure 1A includes a device mounting substrate 10, a component mounting substrate 20, and a connector substrate 30. The device mounting substrate 10 is a substrate in which at least a semiconductor device 16 is mounted on an insulating substrate 11 made of ceramic such as aluminum nitride or aluminum oxide. In this embodiment, the semiconductor device 16 is a semiconductor switching element such as a field-effect transistor (FET) or a metal-oxide semiconductor field-effect transistor (MOSFET). In this specification, FETs and MOSFETs are collectively referred to as "field-effect transistors." The power module 1 is an intelligent power module (IPM) that incorporates a gate drive circuit 23, which will be described later.

[0022] The component mounting board 20 is a board on which mounted components are mounted. The mounted components are composed of electric and electronic components. Examples of electric components include passive elements such as capacitor 27 electrically connected to semiconductor element 16. Examples of electronic components include active elements such as transistors that constitute gate drive circuit 23. The component mounting board 20 includes a printed circuit board 21, and the mounted components are attached to the printed circuit board 21. In this embodiment, electric and electronic components are mounted on the component mounting board 20. However, if the power module 1 is a diode module, only electric components may be mounted. Furthermore, in this embodiment, a capacitor 27 is mounted as an electric component, but a resistor may also be mounted as a passive element. Either an electric component or an electronic component may be mounted. Furthermore, although one component mounting board 20 is disposed between the component mounting board 10 and the connector board 30, multiple component mounting boards 20 may be disposed facing each other between the component mounting board 10 and the connector board 30.

[0023] The connector board 30 is a board that is electrically connected to the mounted components of the component mounting board 20. The connector board 30 includes a printed circuit board 31 as a board body. The connector board 30 has a connector plug 38 to which a predetermined voltage is applied as a connection part that is electrically connected to an external device. The connector board 30 also has connection parts 53a, 54a that are connected to adjacent board structures 1A, etc. A lead resistor 33 and a capacitor 37 are mounted on the connector board 30.

[0024] The element mounting board 10, the component mounting board 20, and the connector board 30 are housed in a casing 70. The element mounting board 10, the component mounting board 20, and the connector board 30 are connected by a plurality of metal supports 50 so as to face each other and maintain a distance between them. More specifically, starting from the bottom of the casing 70, the element mounting board 10, the component mounting board 20, and the connector board 30 are detachably connected by the plurality of supports 50 at intervals. In other words, each support 50 functions as a spacer between the boards. The casing 70 also houses a sealant 60 that seals at least the element mounting board 10 and the component mounting board 20 (see FIG. 3). The sealant 60 may fill the entire interior of the casing 70, but in this embodiment, the sealant 60 fills the casing 70 to a predetermined height from the bottom surface (see the dashed line in FIG. 3). Specifically, the sealing material 60 is filled in the casing 70 up to a height (predetermined height) at which the light receiving surface 26a of the optical receiver 26, which will be described later and which receives an optical fiber (not shown), is not covered by the sealing material 60. In this way, since the sealing material 60 is filled up to a predetermined height from the bottom surface of the casing 70, the space inside the casing 70 that exceeds the predetermined height becomes an unfilled space S that is not filled with the sealing material.

[0025] In this embodiment, the component mounting board 10, the component mounting board 20, and the connector board 30 are housed in a casing 70. In this housed state, the component mounting board 10 and the component mounting board 20 face each other, and the component mounting board 20 and the connector board 30 face each other. The casing 70 includes a pair of opposing first side walls 71, 71 and panel-like second side walls 72, 72 connected to the first side walls 71, 71 on both sides. The first side walls 71 and the second side walls 72 are made of a resin material. A heat sink 76, such as a copper plate, is provided on the casing 70 as a bottom wall of the casing 70. The heat sink 76 is in contact with the insulating substrate 11 of the component mounting board 10. The heat sink 76 is fixed to the first side wall 71 and the second side wall 72 with fixtures (not shown) or the like, thereby forming the casing 70 into a housing with an open top.

[0026] As shown in FIG. 2(A), the first side wall 71 has a plurality of grooves 73 formed at intervals on its outer side along its width direction. Each groove 73 extends along the depth direction of the casing 70. As a result, a protrusion is formed on the outer surface of the first side walls 71, 71 along the depth direction of the casing 70, and this protrusion functions as a heat dissipation fin. Furthermore, the heat dissipation plate 76 has mounting holes 74 formed at positions facing the ends (lower ends) of each groove 73 for mounting the casing 70 (heat dissipation plate 76). As a result, a tool such as a screwdriver (not shown) can be inserted along the grooves 73, a fastener (not shown) inserted into the mounting hole 74 can be engaged with the tool, and the casing 70 can be easily mounted to an external support (not shown) or the like using the fastener.

[0027] Furthermore, as shown in FIG. 2(B), a heat sink 77 is provided in the center of the rear surface of the heat sink 76. The heat sink 77 has a plurality of metal heat dissipation fins 77a protruding from the rear surface of the heat sink 76. An O-ring 78 is arranged around the heat sink 77 so as to surround the plurality of heat dissipation fins 77a of the heat sink 77. By bringing cooling water into contact with the heat sink 77, heat from the heat sink 76 can be absorbed. The O-ring 78 can prevent leakage of cooling water.

[0028] 2. Assembly structure of substrate structure 1A As described above, in this embodiment, as shown in FIGS. 1 and 4, starting from the bottom of the casing 70, the element mounting board 10, the component mounting board 20, and the connector board 30 are detachably connected at intervals by a plurality of supports 50. The supports 50 function as connection terminals 51 to 54. The connection terminals 51 to 54 are electrically connected to mounted components such as the connector plug 38, the capacitor 27, and components of the gate drive circuit 23, or to the semiconductor element 16, etc. In this embodiment, the connection terminals 51 to 54 are composed of a reference voltage connection terminal 51, a drain connection terminal 52, a source connection terminal 53, and a drive voltage connection terminal 54.

[0029] Here, the element mounting board 10, the component mounting board 20, and the connector board 30 are rectangular in plan view. Two reference voltage connection terminals 51, a drain connection terminal 52, and a source connection terminal 53 are provided upright from the four corners of the element mounting board 10. Each of the connection terminals 51 to 53 is inserted into a through-hole 29 formed at the four corners of the component mounting board 20. Connection portions 51a to 53a, which are the ends (upper ends) of each of the connection terminals 51 to 53, are arranged to fit within the respective through-holes 39 formed at the four corners of the connector board 30 in plan view. Therefore, the ends of each of the connection terminals 51 to 53 are exposed from the connector board 30 at the through-holes 39 in plan view of the connector board 30. In this way, as will be described later, female threaded portions 56c formed at the ends of each of the connection terminals 51 to 53 can be threaded with fasteners (not shown) such as screws to function as connectors for mechanical connection (see, for example, FIG. 6(D)). As a result, the connector substrate 30 is sandwiched between the fasteners and the connection terminals 51 to 53, and the connector substrate 30 can be fixed by the fasteners to each of the connection terminals 51 to 53. In addition, among the ends of each of the connection terminals 51 to 53, the ends of the drain connection terminal 52 and the source connection terminal 53 can function as connection parts that are electrically connected to the adjacent substrate structure 1A or an external device, etc., via the wiring 93.

[0030] As long as each of the connection terminals 51 to 53 can support the connector substrate 30 and these connection portions 51 a to 53 a are contained within the through-holes 39 formed at the four corners of the connector substrate 30 in a plan view, the positions of the ends (connection portions 51 a to 53 a) of each of the connection terminals 51 to 53 are not particularly limited. For example, in this embodiment, the ends of each of the connection terminals 51 to 53 are in contact with the lower periphery of the through-hole 39 of the connector substrate 30. Therefore, the connection portions 51 a to 53 a of each of the connection terminals 51 to 53 are disposed facing the through-hole 39. Alternatively, the ends of each of the connection terminals 51 to 53 may be located inside the through-hole 39 of the connector substrate 30. Furthermore, each of the connection terminals 51 to 53 may be inserted through the through-hole 39, with the ends of each of the connection terminals 51 to 53 protruding from the through-hole 39 of the connector substrate 30.

[0031] Furthermore, a support pillar 50 supporting the connector substrate 30 is provided on the component mounting substrate 20 between the reference voltage connection terminal 51 and the drain connection terminal 52 along the longitudinal direction of the component mounting substrate 20. This support pillar 50 is a drive voltage connection terminal 54 to which a gate drive voltage for driving the gate drive circuit 23 is input. Therefore, the drive voltage connection terminal 54 is provided in a position adjacent to the gate drive circuit 23 so as to support the connector substrate 30. An end of the drive voltage connection terminal 54 is disposed within the through-hole 39 in a plan view of the connector substrate 30. The end of the drive voltage connection terminal 54 is a connection portion 54a that is mechanically connected to a fastener (not shown) such as a screw. The position of this connection portion 54 is the same as the end of the connection terminals 51 to 53, and therefore a detailed description thereof will be omitted. By using the support pillar 50 as the connection terminals 51 to 54 that are electrically connected to the mounted components or semiconductor elements 16, the structure of the power module can be simplified.

[0032] The connection terminals 51 to 53, which are each support pillar 50, are cylindrical metal terminals. Each connection terminal 51 to 53 is made up of first support pillars 51A to 53A and second support pillars 51B to 53B. The first support pillars 51A to 53A stand upright from the element mounting board 10 and support the component mounting board 20. The second support pillars 51B to 53B stand upright from the component mounting board 20 and support the connector board 30.

[0033] As shown in FIG. 5, the first support columns 51A to 53A have female threads 56c formed at their ends (upper ends). The second support columns 51B to 53B have male threads 56b formed at their ends (lower ends) to be threaded into the female threads 56c. As shown in FIG. 6(B), the male threads 56b are portions that protrude from the cylindrical support column main body 56a. In this embodiment, as shown in FIG. 6(C), the male threads 56b and the female threads 56c are threadedly engaged with each other via through holes 29 formed in the component mounting board 20. In this threaded state, the component mounting board 20 is clamped at its four corners by the first support columns 51A to 53A and the second support columns 51B to 53B. Similarly, the drive voltage connection terminal 54 has a first support pillar 54A having a female thread portion 56c formed thereon and a second support pillar 54B having a male thread portion 56b formed thereon, the male thread portion 56b being threadedly engaged with the female thread portion 56c. In this embodiment, the first support pillars 51A to 54A have the female thread portion 56c formed thereon, and the second support pillars 51B to 54B have the male thread portion 56b formed thereon, and these are threadedly engaged with each other. However, as long as these can be threadedly engaged with each other, the first support pillars 51A to 54A may have the male thread portion 56b formed thereon, and the second support pillars 51B to 54B may have the female thread portion 56c formed thereon.

[0034] In this embodiment, as described above, the sealant 60 is filled up to a predetermined height from the bottom surface of the casing 70. The space inside the casing 70 that exceeds this predetermined height becomes the unfilled space S of the sealant 60 (see FIG. 3). In this embodiment, at least the cylindrical portions of the connection terminals 51 to 54 that exist in the unfilled space S are inserted into a cylindrical insulating cylinder 58 made of ceramic. Specifically, as shown in FIGS. 4, 5, and 6(A) and (B), in this embodiment, the entire cylindrical support column bodies 56a of the second support columns 51B to 53B and the entire cylindrical portion of the drive voltage connection terminal 54 are covered by the insulating cylinder 58. Note that only the portions that exist in the unfilled space S may be covered by the insulating cylinder.

[0035] The peripheral surfaces of the connection terminals present in the unfilled space S are more susceptible to discharge than the peripheral surfaces covered with the sealing material 60. In this embodiment, the cylindrical portions (support post bodies 56a) of the connection terminals 51 to 54 present in the unfilled space S are inserted into an insulating cylinder 58 made of ceramic, so that the cylindrical portions can be covered by the insulating cylinder 58. This makes it possible to suppress discharge from the cylindrical portions. Furthermore, in this embodiment, as shown in FIG. 6(C), an O-ring 59 is disposed on the end face of the insulating cylinder 58. By tightening the male thread portion 56b into the female thread portion 56c, the O-ring 59 is deformed, which makes it possible to prevent the inflow of uncured sealing material 60A, which will be described later, into the interior 58a of the insulating cylinder 58.

[0036] As shown in FIGS. 2A and 5, the connection portions 51a to 54a, which are the ends (upper ends) of the connection terminals 51 to 54, are arranged to fit within the respective through-holes 39 in a plan view of the connector substrate 30. Therefore, the connection portions 51a to 54a of the connection terminals 51 to 54 are exposed from the connector substrate 30 at the through-holes 39 in a plan view of the connector substrate 30. A female screw portion 56c is formed in each of the connection portions 51a to 54a. In the case of the drain connection terminal 52 or the source connection terminal 53 among the connection terminals 51 to 53, as shown in FIG. 6D, a fastener 92 such as a screw inserted through the through-hole 39 is threaded into the female screw portion 56c, and a wiring 93 is fixed via a washer 91. In this way, a wiring 93 from a power source or an adjacent substrate structure 1A can be connected to the connection portion 52a, 53a of the drain connection terminal 52 or the source connection terminal 53 shown in FIG. 2A. In addition, by screwing and tightening fasteners 92 into the female threads 56c formed on the connection portions 51a to 54a of the connection terminals 51 to 53, the connector board 30 can be stably fixed while being supported by the connection terminals 51 to 54. Note that a tightening groove 56f that engages with the tip of a flat-head screwdriver (not shown) is formed on the upper end surfaces (connection portions 51a to 54a) of the second support columns 51B to 54B so as to intersect with the female threads 56c (see, for example, FIG. 6(A)). This allows the second support columns 51B to 54B to be easily attached to the first support columns 51A to 54A with a flat-head screwdriver.

[0037] According to this embodiment, starting from the bottom of casing 70, element mounting board 10, component mounting board 20, and connector board 30 are detachably connected at intervals by a plurality of supports 50. This allows element mounting board 10, component mounting board 20, and connector board 30 to be easily separated. In particular, if, during inspection, electrical components such as lead resistors 33 and capacitors 27, 37 mounted on component mounting board 20 or connector board 30 do not have the desired characteristics, component mounting board 20 or connector board 30 can be easily replaced.

[0038] Furthermore, while the component mounting board 20 is sandwiched between the first support columns 51A-53A and the second support columns 51B-53B, the male threaded portion 56b and the female threaded portion 56c are screwed into through holes 29 formed in the component mounting board 20. By releasing the screw connection between the first support columns 51A-53A and the second support columns 51B-53B, the component mounting board 20 can be easily removed from between the element mounting board 10 and the connector board 30. Furthermore, by screwing the male threaded portion 56b and the female threaded portion 56c into through holes 29 formed in the component mounting board 20 and tightening the second support columns 51B-53B into the first support columns 51A-53A, the component mounting board 20 can be stably fixed to the element mounting board 10 and the connector board 30.

[0039] Furthermore, according to this embodiment, heat generated from semiconductor elements 16 mounted on element mounting board 10 is easily dissipated from heat sink 76 in contact with insulating substrate 11. On the other hand, heat generated from components mounted on component mounting board 20 (for example, electronic components of gate drive circuit 23, capacitor 27), lead resistors 33 of connector board 30, and capacitors 37 is easily conducted through metal support posts 50 via each board and dissipated to the outside.

[0040] Furthermore, because the element mounting board 10, the component mounting board 20, and the connector board 30 are arranged facing each other but spaced apart, heat generated by mounted components such as the semiconductor element 16 and the gate resistor 15R (described later) is also dissipated between them. This dissipated heat is also dissipated to the outside from the metal support posts 50 via the sealing material 60. Therefore, even if the sealing material 60 is housed inside the casing 70, heat input to the sealing material 60 is unlikely to be stored in the sealing material 60 as sensible heat, and can be dissipated to the outside from the metal support posts 50. In this way, heat generated by the element mounting board 10, the component mounting board 20, and the connector board 30 can be dissipated efficiently.

[0041] Here, the support posts 50 are connection terminals 51 to 54 electrically connected to the semiconductor element 16 and the above-mentioned mounted components. Therefore, heat generated from the semiconductor element 16 and the mounted components is easily transferred to the connection terminals 51 to 54 via these conductive paths (not shown). As a result, the heat generated from the semiconductor element 16 and the mounted components is easily dissipated to the outside (above the casing 70) via the connection terminals 51 to 54, from the element mounting board 10 side toward the connector board 30 side.

[0042] In particular, the connection terminals 51 to 53 erected from the four corners of the element mounting board 10 are inserted into the through-holes 29 at the four corners of the component mounting board 20, and are further exposed at the four corners of the connector board 30 at the through-holes 39 in a plan view of the connector board 30. Therefore, heat generated from the semiconductor element 16 and the above-mentioned mounted components is dispersed and transferred in a balanced manner to the connection terminals 51 to 53 located at the four corners, and can be efficiently dissipated to the outside through the through-holes 39 of the connector board 30. In particular, although the number of reference voltage connection terminals 51 may be one in terms of function, providing multiple reference voltage connection terminals 51 (two in this embodiment) allows heat generated in integrated circuits such as the gate drive circuit 23 of the component mounting board 20 to be efficiently dissipated from the multiple (two) reference voltage connection terminals 51.

[0043] 3. Structure of the element mounting substrate 10 and circuit configuration of the power module 1 The structure of the device mounting substrate 10 and the circuit configuration of the power module 1 will be described below with further reference to FIGS. 7 to 9. As shown in FIG. 7(A), a conductor pattern 12P including at least a conductive layer 12 on which a semiconductor device 16 is mounted is formed on the surface of an insulating substrate 11. Each conductive layer 12 has rounded convex or concave corners in a planar view to suppress discharge. In this embodiment, the conductor pattern 12P is formed of a metal foil such as copper foil. The conductor pattern 12P has planar first to third conductive layers 12A to 12C as the conductive layers 12. The surface of the insulating substrate 11, together with the periphery of the second conductive layer 12B, is covered with an insulating film 14 so that a mounting area 13C on the surface of the second conductive layer 12B where the semiconductor device 16 is mounted is exposed. Specifically, an element opening 14c (opening 14H) having a shape corresponding to the shape of the mounting surface of the semiconductor element 16 is formed in the insulating film 14, and thus the mounting area 13C (13) has a shape corresponding to the shape of the mounting surface of the semiconductor element 16. With the semiconductor element 16 mounted in the mounting area 13C, the semiconductor element 16 is solder-bonded to the second conductive layer 12B in the mounting area 13C by reflow or the like.

[0044] The semiconductor element 16 is a field-effect transistor, and as described above, the component mounting substrate 20 is provided with a gate drive circuit 23. The gate drive circuit 23 is an electronic circuit composed of mounted components such as electronic components and drives the semiconductor element 16, which is a field-effect transistor. The gate drive circuit 23 receives a voltage from a drive voltage connection terminal 54. The gate drive circuit 23 controls the waveform of the gate drive voltage using an optical signal (pulse signal) received by the optical receiver 26 as a control signal, and generates a pulse signal consisting of a PWM signal. In this embodiment, the component mounting substrate 20 has the optical receiver 26 and the gate drive circuit 23 arranged side by side on one side of the optical input port 25. By arranging the gate drive circuit 23 and the optical receiver 26 side by side on one side of the optical input port 25, the optical receiver 26 can be positioned near the gate drive circuit 23. This allows the optical signal received by the optical receiver 26 to be input to the gate drive circuit 23 with high accuracy. This allows the gate drive circuit 23 to generate a pulse waveform of the gate drive voltage that drives (switches) the semiconductor element (field effect transistor) 16 with high precision.

[0045] An interposer (intermediate board) 15 that connects the gate drive circuit 23 and the semiconductor element 16 (field-effect transistor) and an intermediate component 17 are mounted on the element mounting board 10, and these are electrically connected with wires (not shown) by wire bonding or the like. The interposer 15 includes a wiring board 15a, and the wiring board 15a is provided with a gate resistor 15R configured as a chip resistor 15b. The wiring board 15a also includes a gate-source resistor. The gate drive circuit 23 is electrically connected to a terminal of a connector 15c mounted on the wiring board 15a.

[0046] In this embodiment, a conductive layer 15d made of copper is formed on the back surface of the interposer 15, and the surface of the conductive layer 15d is further coated with solder. The surface of the insulating substrate 11, along with the periphery of the first conductive layer 12A, is covered with an insulating film 14 so that a mounting area 13A on which the interposer 15 is to be mounted is exposed. Specifically, an interposer opening 14a (opening 14H) shaped to correspond to the shape of the mounting surface of the interposer 15 is formed in the insulating film 14, so that the mounting area 13A (13) has a shape that corresponds to the shape of the mounting surface of the interposer 15. With the interposer 15 mounted in the mounting area 13A, the interposer 15 is solder-bonded to the first conductive layer 12A in the mounting area 13A by reflow or the like.

[0047] A mounting area 13D on which relay component 17 is mounted is formed on the surface of second conductive layer 12B. Similarly, component opening 14d (opening 14H) is formed in relay component 17, so that mounting area 13D (13) has a shape corresponding to the shape of the mounting surface of relay component 17. With relay component 17 mounted in mounting area 13D, relay component 17 is solder-joined to third conductive layer 12C in mounting area 13D by reflow or the like.

[0048] Furthermore, the above-mentioned connection terminals 51-53 are provided upright on the conductor pattern 12P so as to be electrically connected directly or indirectly to the semiconductor element 16 or the like via the first to third conductive layers 12A-12C (conductive layers 12). Terminal openings 14b, 14e, and 14f corresponding to the shapes of the end faces of the connection terminals are formed in the insulating film 14 at the positions where the connection terminals 51-53 are provided. As a result, contact regions 13B, 13E, and 13F that are exposed from the insulating film 14 and come into contact with the end faces of the connection terminals 51-53 are formed on the surfaces of the first to third conductive layers 12A-12C (conductive layers 12) of the conductor pattern 12P, respectively. Each of the connection terminals 51-53 is joined to the corresponding first to third conductive layers 12A-12C by soldering at the contact regions 13B, 13E, and 13F. The connection terminals 51 to 53 are cylindrical metal terminals, and therefore have rounded side surfaces, which can suppress discharge from the connection terminals 51 to 53. In this embodiment, the connection terminals 51 to 53 are cylindrical terminals, but the connection terminals 51 to 53 may also be polygonal pillar terminals with rounded corners (ridges).

[0049] In the connector substrate 30, a voltage supplied from an external device to the connector plug 38 is converted into a reference voltage and a gate drive voltage. The converted reference voltage is supplied to the reference voltage connection terminal 51 and input to the first conductive layer 12A via the reference voltage connection terminal 51. Therefore, the first conductive layer 12A functions as a reference voltage conductive layer. Meanwhile, the gate drive voltage is supplied to the drive voltage connection terminal 54 and input to the gate drive circuit 23. The gate drive voltage having a pulsed waveform is generated in the gate drive circuit 23 from the gate drive voltage and the optical signal (PWM signal). The potential of the gate drive voltage generated in the gate drive circuit 23 is adjusted to an appropriate potential by the reference voltage input to the first conductive layer 12A. This gate drive voltage is applied as a gate drive signal between the gate and source of the semiconductor element 16.

[0050] Furthermore, of the connection terminals 51 to 53, the drain connection terminal 52 is a terminal connected to a drain terminal (not shown) of the semiconductor element (field effect transistor) 16. The second conductive layer 12B is a drain conductive layer that is electrically connected to the drain terminal of the semiconductor element (field effect transistor) 16. Furthermore, of the connection terminals 51 to 53, the source connection terminal 53 is a terminal that is connected to a source terminal (not shown) of the semiconductor element (field effect transistor) 16. The third conductive layer 12C is a source conductive layer that is electrically connected to the source terminal of the semiconductor element (field effect transistor) 16. The drain connection terminal 52 is provided upright on the second conductive layer (drain conductive layer) 12B. The source connection terminal 53 is provided upright on the third conductive layer (source conductive layer) 12C.

[0051] In this way, heat generated by the semiconductor element (field-effect transistor) 16 is transferred from the second conductive layer (conductive layer for drain) 12B and the third conductive layer (conductive layer for source) 12C, which are electrically connected to the source terminal and the drain terminal, through the insulating substrate 11 to the heat sink 76, where it is dissipated from the heat sink 76. Furthermore, the heat generated by the semiconductor element (field-effect transistor) 16 can also be dissipated from the source connection terminal 53 and the drain connection terminal 52, which are provided on the second conductive layer (conductive layer for drain) 12B and the third conductive layer (conductive layer for source) 12C, respectively. Meanwhile, the gate resistor 15R mounted on the interposer 15 also generates heat together with the semiconductor element 16. The heat generated by this gate resistor 15R is transferred from the first conductive layer (conductive layer for gate resistor) 12A, which is indirectly connected to the gate terminal, to the heat sink 76, where it can be dissipated from the heat sink 76.

[0052] As shown in FIG. 8A , the surface of insulating substrate 11, along with the periphery of conductive layer 12, is covered with insulating film 14 so that mounting area 13, where semiconductor element 16 is mounted, is exposed. Here, the periphery of conductive layer 12 refers to the periphery including the surface and side surfaces of conductive layer 12. This prevents electric field concentration at the peripheral convex and concave portions of conductive layer 12, thereby preventing discharge from these convex and concave portions. Based on the results of analysis conducted by the inventors, it is preferable that mounting area 13 be formed 5 mm or more inward from the periphery of conductive layer 12. This prevents discharge near mounting area 13.

[0053] Furthermore, the opening 14H formed in the insulating film 14 allows the mounting area 13 to be shaped according to the shape of the mounting surface of the semiconductor element 16 or the like, thereby reducing the area of ​​the conductive layer 12 exposed from the insulating film 14. This reduces discharge from the conductive layer 12. Furthermore, the terminal openings 14b, 14e, and 14f formed in the insulating film 14 form contact areas 13B, 13E, and 13F on the surface of the conductive layer 12 of the conductor pattern 12P that are exposed from the insulating film 14 and come into contact with the end faces of the connection terminals 51 to 53. This allows the insulating film 14 to cover the peripheries of the contact areas 13B, 13E, and 13F of the conductive layer on which the connection terminals 51 to 53 are provided, thereby reducing discharge from the periphery of the conductive layer 12. Based on the results of analysis conducted by the inventors, it is preferable that the contact areas 13B, 13E, and 13F be formed 5 mm or more inward from the periphery of the conductive layer 12. This makes it possible to suppress discharge in the vicinity of the contact areas 13B, 13E, and 13F.

[0054] Here, the dielectric breakdown strength of the insulating film 14 is preferably higher than that of the sealing material 60, for example, preferably 200 kV / mm or more. The insulating film 14 can be made of a resin material such as a polyimide resin. The sealing material 60 has a dielectric breakdown strength of about 20 kV / mm, and the sealing material 60 can be made of a gel insulating material such as silicon gel.

[0055] Furthermore, as shown in FIG. 8(A), a recess 11b is formed by the mounting area 13 and the opening 14H, and a plating layer 18 may be further formed in the mounting area 13 so as to fill at least a portion of the recess 11b. The plating layer 18 is, for example, a layer made of boron nickel formed by electroless nickel plating. In this case, the surface 18a of the plating layer 18 corresponds to the mounting area where the semiconductor element 16 is mounted. In this embodiment, the thickness of the plating layer 18 is equal to or less than the depth of the recess 11b. Furthermore, a conductive layer 19A and a plating layer 19B made of copper are formed on the back surface of the insulating substrate 11, and these layers serve as earth. Alternatively, as shown in FIG. 8(B), an adhesive layer 14B thicker than the conductive layer 12 may be provided, and an insulating film 14A may be disposed on top of this. This allows the insulating film 14A to be provided along the edges of the insulating substrate 11 and the conductive layer 12 while the insulating film 14A is flat. The insulating films 14 and 14A are attached to the edges of the insulating substrate 11 and the conductive layer 12 by vacuum lamination.

[0056] According to this embodiment, the thickness of the plating layer 18 formed on the surface of the conductive layer 12 is set to be equal to or less than the depth of the recess 11b formed by the mounting area 13 and the opening 14H. This prevents the periphery of the plating layer 18 from protruding from the insulating film 14. As a result, it is possible to suppress the concentration of an electric field at the periphery of the plating layer 18 and to suppress discharge from this periphery.

[0057] Power module 1 is provided with a plurality of resistors, of which chip resistor 15b is provided on component mounting substrate 10, and lead resistor 33 is provided on connector substrate 30. Lead resistor 33 is connected between drain connection terminal 52 and source connection terminal 53 to stabilize the voltage between them, and capacitors 27, 37 are provided on component mounting substrate 20 and connector substrate 30, respectively, for the same purpose. Lead resistor 33 may also be provided on component mounting substrate 20.

[0058] By arranging the resistors in this manner, the lead resistors 33 are mounted on at least one of the component mounting board 20 and the connector board 30, which are spaced apart from the element mounting board 10. Therefore, heat generated from the lead resistors 33 can be dissipated to the outside from the connector board 30 side. On the other hand, the chip resistors 15b, which generate less heat than the lead resistors 33, are provided on the element mounting board 10, and therefore can dissipate heat to the outside via the heat sink 76. In this way, the lead resistors 33, which generate more heat than the chip resistors 15b, dissipate heat to the outside from the connector board 30 side, and therefore the heat generated by the semiconductor elements 16 can be dissipated more efficiently from the heat sink 76.

[0059] Furthermore, heat generated by the gate drive circuit 23 can be dissipated from the metal support posts 50 (reference voltage connection terminals 51). Meanwhile, an interposer 15 that relays the gate drive circuit 23 and the semiconductor element (field-effect transistor) 16 is mounted on the element mounting substrate 10, and the interposer 15 is provided with a gate resistor 15R configured with a chip resistor 15b. This allows the heat generated from the gate resistor 15R to be dissipated from the heat sink 76. In this way, the heat generated from the gate drive circuit 23 and the gate resistor 15R can be dispersed.

[0060] 4. Regarding the inclusion of sealing material 60 (60A) 9, component mounting board 20 is rectangular, and has an inlet 25 formed in the center of component mounting board 20 for introducing sealing material 60A that seals component mounting board 10 within casing 70. Furthermore, as described above, component mounting board 20 is mounted with optical receiver 26, as one of the mounted components, which is connected to an optical fiber and receives an optical signal from the optical fiber (not shown). Connector board 30 has an opening 35 formed in a position opposite optical receiver 26.

[0061] According to this embodiment, an inlet 25 is formed in the center of component mounting board 20, through which sealing material 60A that seals component mounting board 10 is introduced into casing 70. This allows uncured liquid sealing material 60A to flow stably from inlet 25 of component mounting board 20 toward component mounting board 10. As a result, the entire surface of component mounting board 10 can be uniformly sealed with sealing material 60A while preventing air bubbles from forming in sealing material 60A.

[0062] Furthermore, before guiding and connecting the optical fiber to the optical receiver 26 through the opening 35, a jig (not shown) for discharging the sealant 60A is inserted using the opening 35 of the connector substrate 30. The sealant 60A discharged from the inserted jig can be introduced from the inlet 25 of the component mounting substrate 20 toward the device mounting substrate 10. This allows the device mounting substrate 10 and the component mounting substrate 20 located further toward the bottom of the casing to be filled with the sealant 60A, while ensuring that the sealant 60A does not adhere to the light receiving surface 26a of the optical receiver 26. The liquid sealant 60A is then hardened. After sealing with the sealant 60A is complete, the optical fiber can be guided to the optical receiver 26 through the opening 35 of the connector substrate 30, and the optical fiber can be easily connected to the optical receiver 26.

[0063] 5. Layout and connection of board structure 1A In this embodiment, a plurality of (e.g., two) element mounting substrates 10, each of which includes an insulating substrate 11 and a semiconductor element 16 mounted on the insulating substrate 11, are arranged side by side within the casing 70, and the plurality of element mounting substrates 10 are electrically connected in series. Specifically, a plurality of (e.g., two) substrate structures 1A, each of which includes an element mounting substrate 10, a component mounting substrate 20, and a connector substrate 30 connected via supports 50, are arranged side by side, and the source connection terminal 53 of one of adjacent substrate structures 1A is electrically connected to the drain connection terminal 52 of the other substrate structure 1A. The source connection terminal 53 and the drain connection terminal 52 to be connected are the adjacent source connection terminal 53 and the drain connection terminal 52 of the pair of substrate structures 1A. Furthermore, a plurality of (e.g., eight) power modules 1 may be arranged in parallel, and the source connection terminal 53 and the drain connection terminal 52 of these adjacent power modules 1 may be connected.

[0064] Such a series connection makes it easy for the multiple device mounting substrates 10 to discharge high voltages from the periphery of the conductive layer 12, but the above-mentioned insulating film 14 can more effectively suppress the discharge. In particular, when multiple substrate structures 1A are arranged side by side, the source connection terminal 53 of one of adjacent substrate structures 1A is electrically connected to the drain connection terminal 52 of the other substrate structure 1A, so that adjacent substrate structures 1A can be connected in series and each substrate structure 1A can be responsible for converting a high-voltage DC voltage to an AC voltage, and the heat generated during the conversion can be dispersed to each substrate structure 1A.

[0065] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made without departing from the spirit of the present invention as set forth in the claims. [Explanation of symbols]

[0066] 1: power module, 1A: substrate structure, 10: element mounting substrate, 11: insulating substrate, 12: conductive layer, 12P: conductor pattern, 13: mounting area, 14, 14A: insulating film, 14H: opening, 15: interposer, 15b: chip resistor, 15R: gate resistor, 16: semiconductor element (field effect transistor), 20: component mounting substrate, 23: gate drive circuit, 25: introduction port, 26: optical receiver, 29: through hole, 30: Connector board, 33: lead resistor, 35: opening, 39: through hole, 50: support, 51: reference voltage connection terminal (connection terminal), 52: drain connection terminal (connection terminal), 53: source connection terminal (connection terminal), 51A to 53A: first support pillar, 51B to 53B: second support pillar, 54: drive voltage connection terminal (connection terminal), 56b: male thread portion, 56c: female thread portion, 58: insulating cylinder, 60: sealing material, 70: casing, 76: heat sink

Claims

1. A high-voltage power module, The power module comprises: an element mounting substrate in which at least a semiconductor element is mounted on an insulating substrate made of ceramic; a component mounting substrate on which mounted components such as electrical or electronic components electrically connected to the semiconductor element are mounted; a connector substrate electrically connected to the mounted component and having a connection portion electrically connected to at least an external device; It has a casing that accommodates the element mounting board, the component mounting board, and the connector board, A power module characterized in that, in order from the bottom of the casing, the element mounting board, the component mounting board, and the connector board are detachably connected at intervals by a plurality of supports.

2. Each of the support columns comprises a first support column extending from the element mounting board and supporting the component mounting board; a second support pillar that stands upright from the component mounting board and supports the connector board, a male screw portion is formed at an end of one of the first support pillar and the second support pillar, and a female screw portion is formed at an end of the other support pillar to be screwed into the male screw portion; 2. The power module according to claim 1, wherein the component mounting substrate is sandwiched between the first support pillar and the second support pillar by screwing the male threaded portion and the female threaded portion together through a through hole formed in the component mounting substrate.

3. an end surface of the support post is exposed from the connector board through a through hole formed in the connector board in a plan view of the connector board; 3. The power module according to claim 2, wherein the support is a connection terminal electrically connected to the mounted component or the semiconductor element.

4. 2. The power module according to claim 1, wherein the component mounting substrate is rectangular, and an inlet is formed in the center of the component mounting substrate for introducing a sealing material that seals the component mounting substrate into the casing.

5. an optical receiver connected to an optical fiber and configured to receive an optical signal from the optical fiber is mounted on the component mounting board as one of the mounted components; 5. The power module according to claim 4, wherein an opening is formed in the connector substrate at a position facing the optical receiver.

6. the semiconductor element is a field effect transistor, the component mounting board is provided with a gate drive circuit configured from some of the plurality of mounted components and configured to drive the field effect transistor; the gate drive circuit controls the waveform of a gate voltage using an optical signal received by the optical receiver as a control signal; 6. The power module according to claim 5, wherein the optical receiver and the gate drive circuit are arranged side by side on one of both sides of the light introduction port on the component mounting substrate.

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