JP2010278107A - Semiconductor device and connection member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device that is made compact and has large amount of electric power supply and suppresses damage to a semiconductor element. <P>SOLUTION: The semiconductor device includes at least one semiconductor element 11, 13, a conductor plates 25 serving as an electric power supply path for a current flowing through the semiconductor element 11, 13, and a connection member 31 for electrically connecting the semiconductor element 11, 13 to the conductor plate 25. The connection member 31 includes a plate-like conductor connection portion 33 coming in contact with the conductor plate substantially in parallel, and a plate-like element connection portion 35 coming in contact with a surface of the semiconductor element 11, 13 on the side of the conductor connection portion 33 substantially in parallel, and has an overlap region D where the conductor connection portion 33 and element connection portion 35 overlap with each other in plane view from a direction orthogonal to the conductor plate 25, the conductor plate 25 and conductor connection portion 33 being joined together by laser welding within the overlap region D. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a semiconductor device comprising: at least one semiconductor element; a conductor plate serving as an energization path for a current flowing through the semiconductor element; and a connection member that electrically connects the semiconductor element and the conductor plate. . The present invention also relates to a connection member that electrically connects at least one semiconductor element and a conductor plate serving as an energization path for current flowing through the semiconductor element.

  In recent years, hybrid vehicles and electric vehicles equipped with rotating electric machines (motors and generators) as driving force sources have attracted attention from the viewpoint of energy saving and environmental load reduction. In such hybrid vehicles and electric vehicles, the current flowing through the rotating electrical machine is controlled by an inverter device (a type of semiconductor device). Here, the inverter device is provided with a switching element (a kind of semiconductor element) such as IGBT and MOSFET, and the switching element converts the DC power from the battery into AC power and supplies it to the rotating electrical machine, or the rotating electrical machine. AC power from is converted to DC power and supplied to the battery. In an in-vehicle inverter device, in order to improve output by a rotating electrical machine, a demand for increasing power is increasing. In addition, when a large current flows through the switching element, the amount of heat generation increases accordingly, so that the demand for heat radiation performance is increasing in order to appropriately protect the switching element.

  As a measure to increase the heat dissipation effect while allowing a large amount of current to flow through the inverter device, it is proposed to use a bus bar (conductor plate) for the current flow path through the switching element. Has been. A semiconductor device configured using such a bus bar is described, for example, in Patent Document 1 below. In the semiconductor device described in Patent Document 1, as shown in FIG. 11, at least one semiconductor element 101 is mounted, and a metal plate 102 bonded to the upper surface of the semiconductor element 101 and bonded to the metal plate 102. And a conductor plate 103 which becomes an energization path of the semiconductor device. The conductor plate 103 and the metal plate 102 are joined by laser welding at a portion other than directly above the semiconductor element 101.

  Thereby, compared with the case where a part of the energization path of the current flowing through the semiconductor element 101 is configured by bonding with, for example, a metallic wire, it is possible to increase the power and increase the heat dissipation effect. In addition, by joining the conductor plate 103 and the metal plate 102 at a portion other than directly above the semiconductor element 103, it is assumed that a through-hole has been generated in the laser joint portion of the metal plate 102 when performing laser welding. In addition, the semiconductor element 101 is suppressed from being directly irradiated with laser light, and the semiconductor element 101 is prevented from being thermally damaged.

JP 2008-098586 A

  However, simply configuring a part of the energization path using a bus bar (conductor plate) does not necessarily increase the capacity of the current flowing through the semiconductor element. That is, since the current capacity flowing between the bus bar (conductor plate) and the metal plate is determined according to the number of spot points (spot area) of laser welding, if the current capacity is to be secured large, the number of spot points (spot area) It can be said that it is necessary to increase. In this respect, in the semiconductor device described in Patent Document 1, since the bus bar (conductor plate) and the metal plate are joined by laser welding while avoiding the portion directly above the semiconductor element, the number of spot points (spot area) will be increased. If so, the area of the laser junction that occupies a portion that does not overlap with the area occupied by the semiconductor element in a plan view as viewed from the upper surface side of the semiconductor element increases. As a result, there is a problem that the entire semiconductor device is increased in size.

  In addition, in order to suppress an increase in the size of the entire semiconductor device, when the joining by laser welding is simply allowed at a portion directly above the semiconductor element, the effect of suppressing thermal damage to the semiconductor element as described above cannot be obtained. .

  The present invention has been made in view of the above-described problems, and provides a semiconductor device capable of reducing the size and increasing the energization amount and suppressing the damage to the semiconductor element. Objective. It is another object of the present invention to provide an electrical connection member that can easily embody such a semiconductor device.

  To achieve this object, at least one semiconductor element according to the present invention, a conductor plate serving as an energization path for a current flowing through the semiconductor element, and a connection member for electrically connecting the semiconductor element and the conductor plate The connecting member includes a plate-like conductor connecting portion that is substantially parallel to the conductor plate, and a surface that is substantially parallel to the surface of the semiconductor element on the conductor connecting portion side. A plate-like element connecting portion that is in contact with each other, and has an overlapping region in which the conductor connecting portion and the element connecting portion overlap each other in a plan view as viewed from a direction orthogonal to the conductor plate, Thus, the conductor plate and the conductor connecting portion are joined by laser welding.

  According to the above characteristic configuration, the conductor connecting portion and the element connecting portion constituting the connecting member have overlapping regions that overlap each other in a plan view as viewed from the direction orthogonal to the conductor plate. When the plate and the conductor connecting portion are joined by laser welding, the element connecting portion functions to shield between the laser joining portion and the semiconductor element. Therefore, even if a through hole is generated in the conductor connection portion during laser welding, the laser light penetrating the conductor connection portion is prevented from being shielded by the element connection portion and directly irradiated onto the semiconductor element. Further, conduction of radiant heat during laser welding to the semiconductor element can be suppressed. Thereby, it can suppress that a semiconductor element receives a thermal damage.

  In addition, even in a region that overlaps the semiconductor element in a plan view as viewed from the direction perpendicular to the conductor plate, the conductor plate and the conductor connection portion are laser-exposed in the overlap region with little concern about thermal damage to the semiconductor element. Since it is possible to join by welding, it is not necessary to secure a separate space for laser welding, for example, compared with the case where the conductor plate and the conductor connecting portion are joined at a portion other than directly above the semiconductor element, the device The overall size can be reduced. Furthermore, since the number of spot points (spot area) for laser welding can be increased relatively freely in the overlapping region, a large amount of current can be secured between the conductor plate and the semiconductor element via the connection member. .

  Therefore, according to the above-described characteristic configuration, it is possible to provide a semiconductor device that can be reduced in size and increased in energization amount, and can suppress damage to the semiconductor element.

  The connecting member further includes a connecting portion that connects the conductor connecting portion and the element connecting portion, the conductor connecting portion and the element connecting portion are arranged substantially parallel to each other, and the connecting portion includes It is preferable that the structure is configured to be elastically deformable in a direction orthogonal to the conductor connection portion and the element connection portion.

According to this configuration, since the connecting portion that connects the conductor connecting portion and the element connecting portion can be elastically deformed, the positional relationship between the conductor connecting portion and the element connecting portion that are arranged substantially in parallel with each other is determined. , And can be relatively displaced in a direction perpendicular to them. Therefore, when the semiconductor device is assembled, even if the distance between the semiconductor element and the conductor plate has some variation, the positional relationship between the conductor connection part and the element connection part is displaced. The variation can be absorbed.
Further, even when the semiconductor device is used in a place where there is a lot of vibration, for example, the vibration is absorbed by displacing the positional relationship between the conductor connection portion and the element connection portion, and the conductor connection portion and the conductor It is possible to reduce the stress applied to the junction between the plate and the connection between the element connection portion and the semiconductor element. Therefore, since the electrical connection between the conductor plate and the semiconductor element via the connection member can be properly maintained, the reliability of the semiconductor device is improved even when used in a place with such a lot of vibration. Can be made.

  Here, the connection member has a shape obtained by bending a plate-like member into a substantially U-shaped cross section, one of two surfaces substantially parallel to each other being the conductor connection portion, and the other being the element connection It is preferable that the configuration is a part.

  The “substantially U-shape” is formed by connecting one end portion of two sides substantially parallel to each other by another side constituted by a curve or a straight line, and forming an approximately U shape as a whole. Means that At that time, as long as it is generally U-shaped as a whole, it may be rounded, angular, or have other shapes.

  According to this configuration, the overlapping region can be easily generated by bending the connection member into a substantially U-shaped cross section. At that time, by adjusting the length of the bent and folded portion, the area of the overlapping region can be appropriately ensured as necessary. Therefore, these merits can be enjoyed while balancing the downsizing of the entire semiconductor device and the increase in the amount of energization.

  The connection member has a shape formed by bending a plate-like member into a substantially Z-shaped cross section, and one of two surfaces substantially parallel to each other is the conductor connection portion, and the other is the element connection portion. It is preferable to adopt the configuration described above.

  In addition, "substantially Z-shaped" means that one end of two sides that are substantially parallel to each other and the other end of the other are connected by another side constituted by a curve or a straight line. It means that it is formed in a Z shape. At that time, as long as it is approximately Z-shaped as a whole, it may be rounded, angular, or have other shapes.

According to this configuration, the overlapping region can be easily generated by bending the connection member into a substantially Z-shaped cross section. Further, at that time, by adjusting the length of each of the portions that are bent twice after being bent, the area of the overlapping region can be appropriately ensured as required. Therefore, these merits can be enjoyed while balancing the downsizing of the entire semiconductor device and the increase in energization capacity.
Furthermore, in this structure, the site | part which connects a conductor connection part and an element connection part among connection members will extend over the whole overlap area | region. Therefore, when the conductor plate and the conductor connection portion are joined by laser welding in the overlapping region, the connection portion in addition to the element connection portion also functions to shield between the laser joint portion and the semiconductor element. become. Moreover, since the length of a connection member becomes long by setting it as a cross-sectional substantially Z shape, the surface area of a connection member can be enlarged and the heat dissipation effect can be raised. Furthermore, in this case, when the plate thickness is made equal, the heat capacity of the connecting member increases, so that heat conduction to the semiconductor element via the connecting member can be suppressed. Therefore, it is possible to more effectively suppress the semiconductor element from being damaged by heat. Alternatively, the thickness can be reduced by reducing the plate thickness while securing the shielding property.

  Further, the semiconductor device includes a plurality of the semiconductor elements, and the connecting member is configured to connect the two semiconductor elements in common to the conductor plate, and the two connecting elements are in contact with the two semiconductor elements, respectively. It is preferable that a connection portion is provided, the conductor connection portion is interposed between the two element connection portions, and the two element connection portions are integrally connected.

According to this configuration, the conductor connection portion and the two element connection portions overlap each other in a two-dimensional view when viewed from a direction orthogonal to the conductor plate, and there is almost no concern about thermal damage to the semiconductor element. The conductor plate and the conductor connection portion can be joined by laser welding. Therefore, the distance between the two semiconductor elements can be shortened, and the entire semiconductor device can be further reduced in size.
In addition, since the conductor plate and the two semiconductor elements can be simultaneously connected using one connecting member, the structure is simplified and the manufacturability is also improved.

  A characteristic configuration of a connecting member for electrically connecting at least one semiconductor element according to the present invention and a conductor plate serving as a current-carrying path for a current flowing through the semiconductor element is in contact with the conductor plate in a substantially parallel manner. A plate-like conductor connecting portion joined by welding and a plate-like element connecting portion in contact with the surface of the semiconductor element on the side of the conductor connecting portion, and viewed from a direction orthogonal to the conductor connecting portion. In the plan view, the conductor connecting portion and the element connecting portion have an overlapping region where they overlap each other.

  According to the above characteristic configuration, the conductor connection portion and the element connection portion have overlapping regions that overlap each other in a plan view as viewed from a direction orthogonal to the conductor connection portion. When joining by means of laser welding in the overlapping region, the element connecting portion can be given a function of shielding between the laser joining portion and the semiconductor element. Therefore, even if a through hole is generated in the conductor connection portion during laser welding, the laser light penetrating the conductor connection portion is prevented from being shielded by the element connection portion and directly irradiated onto the semiconductor element. Further, conduction of radiant heat during laser welding to the semiconductor element can be suppressed. Thereby, it can suppress that a semiconductor element receives a thermal damage.

  Moreover, a conductor plate and a semiconductor element can be electrically connected compactly by connecting a conductor plate and a conductor connection part, and a semiconductor element and an element connection part in an overlapping region. Furthermore, since the number of spot points (spot area) for laser welding can be increased relatively freely in the overlapping region, it is possible to ensure a large energization amount between the conductor plate and the semiconductor element.

  Therefore, according to the above-described characteristic configuration, a connection member that can easily realize a semiconductor device that can be reduced in size and increased in energization amount and can suppress damage to a semiconductor element. Can be provided.

It is a block diagram which shows typically the circuit structure of the inverter apparatus which concerns on 1st embodiment. It is sectional drawing of the switching module which concerns on 1st embodiment. It is a top view of the switching module concerning a first embodiment. It is a perspective view of a switching module concerning a first embodiment. It is sectional drawing of the switching module which concerns on 2nd embodiment. It is sectional drawing of the switching module which concerns on 3rd embodiment. It is sectional drawing of the switching module which concerns on other embodiment. It is sectional drawing of the switching module which concerns on other embodiment. It is sectional drawing of the switching module which concerns on other embodiment. It is sectional drawing of the switching module which concerns on other embodiment. It is a figure which shows a prior art.

[First embodiment]
A first embodiment of the present invention will be described with reference to the drawings. In the present embodiment, a case where the semiconductor device according to the present invention is applied to a switching module 8 constituting an inverter device 7 for controlling the rotating electrical machine 3 will be described as an example. In the present embodiment, the inverter device 7 is used for controlling the rotating electrical machine 3 provided in the electric vehicle or the hybrid vehicle. The rotating electrical machine 3 can function both as a motor (electric motor) that generates power upon receiving power supply and as a generator (generator) that generates power upon receiving power supply. It is possible.

1. First, a schematic configuration of the inverter device 7 will be described. FIG. 1 is a block diagram schematically showing a circuit configuration of the inverter device 7 according to the present embodiment. As shown in FIG. 1, this inverter circuit is a circuit for driving the rotating electrical machine 3. In the present embodiment, the rotating electrical machine 3 is configured to be driven by a three-phase alternating current, and this inverter circuit is configured by a bridge circuit. That is, the two switching elements 11 are connected in series between the positive electrode P side serving as the power supply voltage and the negative electrode N side serving as the ground, and this series circuit is connected in parallel in three lines. A series circuit of a pair of switching elements 11 corresponds to each of the stator coil U phase, V phase, and W phase of the rotating electrical machine 3.

In FIG.
Reference numeral 11a is a U-phase upper switching element.
Reference numeral 11b is a V-phase upper switching element.
Reference numeral 11c is a W-phase upper switching element,
Reference numeral 11d is a U-phase lower switching element,
Reference numeral 11e is a V-phase lower switching element,
Reference numeral 11f is a W-stage lower switching element.
As these switching elements 11a to 11f, it is preferable to apply an insulated gate bipolar transistor (IGBT), a metal oxide semiconductor field effect transistor (MOSFET) or the like. In this example, an example in which an IGBT is used is shown.

  As shown in FIG. 1, the collectors of the upper switching elements 11a, 11b, and 11c of each phase are connected to the positive electrode P side, and the emitters are connected to the collectors of the lower switching elements 11d, 11e, and 11f of each phase. . The emitters of the lower switching elements 11d, 11e, and 11f of each phase are connected to the negative electrode N side. The gates of the switching elements 11a to 11f are connected to a control unit (not shown) and are individually controlled to be switched. That is, the control unit supplies the three-phase AC power to the rotating electrical machine 3 by performing PWM control on the switching elements 11 a to 11 f based on the required rotational speed and the required torque required for the rotating electrical machine 3. As a result, the rotating electrical machine 3 is caused to power according to the required rotational speed and the required torque. On the other hand, when the rotating electrical machine 3 functions as a generator and receives supply of electric power from the rotating electrical machine side, the control unit controls the switching elements 11a to 11f so as to convert the generated alternating current into direct current.

  A diode element 13 is connected in parallel between the emitter and collector of each of the switching elements 11a to 11f. Here, the diode element 13 has an anode connected to the emitters of the switching elements 11a to 11f and a cathode connected to the collectors of the switching elements 11a to 11f. The diode element 13 is used as an FWD (Free Wheel Diode). In the present embodiment, the switching element 11 and the diode element 13 correspond to the “semiconductor element” in the present invention. And each switching element 11a-11f and each diode element 13 are electrically connected by the connection member 31 mentioned later (refer FIG. 2). In addition, the switching module 8 is comprised by the switching element 11 and the diode element 13 which become a pair, respectively. In the present embodiment, the switching module 8 corresponds to the “semiconductor device” in the present invention.

  The intermediate points (connection points of the switching elements) 12u, 12v, 12w of the series circuit by the switching elements (11a, 11d), (11b, 11e), (11c, 11f) of the respective phases are respectively The coils are connected to phase coils 15u, 15v, and 15w, respectively. Here, the connection member 31 that connects each of the switching elements 11a to 11f and each of the diode elements 13 and the coils 15u, 15v, and 15w of each phase are electrically connected by a bus bar 25 described later. In the present embodiment, the bus bar 25 corresponds to the “conductor plate” in the present invention.

2. Specific Configuration of Inverter Device Next, a specific configuration of each switching module 8 configuring the inverter device 7 will be described. FIG. 2 is a cross-sectional view of the switching module 8 according to the present embodiment, and FIG. 3 is a plan view of the switching module 8 according to the present embodiment. FIG. 4 is a perspective view of the switching module 8 according to the present embodiment. As shown in these drawings, the switching module 8 includes a base plate 21, an insulating substrate 23, a switching element 11 and a diode element 13 as semiconductor elements, a connection member 31, and a bus bar 25. The base plate 21, the insulating substrate 23, the switching element 11, and the diode element 13 are stacked in this order. A connection member 31 is disposed so as to electrically connect the switching element 11 and the diode element 13, and a bus bar 25 is further connected to the connection member 31. In such a switching module 8, the present invention is based on the structure of the connection member 31 for electrically connecting the switching element 11 and the diode element 13 and the bus bar 25 and the connection structure of the connection member 31 and the bus bar 25. Has characteristics. Hereinafter, the detail of each part of the switching module 8 which concerns on this embodiment is demonstrated.

  The base plate 21 is a plate-like member serving as a base for stacking the insulating substrate 23, the switching element 11, and the diode element 13. In the present embodiment, the base plate 21 is shared among the switching modules 8. The base plate 21 is made of a metal material such as copper or aluminum. A plate-like insulating substrate 23 is placed on the upper surface of the base plate 21. Copper foils (not shown) formed by a DBC (Direct Bonding Copper) method or the like are provided on both upper and lower surfaces of the insulating substrate 23. The copper foil on the lower surface side of the insulating substrate 23 is fixed to the base plate 21 with solder, whereby the insulating substrate 23 is fixed on the base plate 21.

  The switching element 11 and the diode element 13 are placed on the upper surface of the insulating substrate 23. The switching element 11 and the diode element 13 are arranged in parallel adjacent to each other on one insulating substrate 23. Here, the switching element 11 and the diode element 13 are fixed to the copper foil on the upper surface side of the insulating substrate 23 with solder. The base plate 21, the insulating substrate 23, the switching element 11 and the diode element 13 are stacked in a substantially parallel state. In the following, these stacking directions are referred to as the Z-axis direction. A direction from the switching element 11 toward the diode element 13 disposed adjacent thereto is defined as an X-axis direction, and a direction orthogonal to the X-axis direction and the Z-axis direction is defined as a Y-axis direction.

  The bus bar 25 is a conductive plate-like member, and is made of a metal material such as copper or aluminum, for example. The bus bar 25 constitutes a part of a current supply path in the switching module 8 and serves as a current supply path for a current flowing through the switching element 11 and the diode element 13. In this example, the bus bar 25 serves as an energization path between the switching element 11 and the diode element 13 and any one of the coils 15u, 15v, and 15w of each phase of the rotating electrical machine 3 as described above. In addition, you may apply to the energization path | route etc. between the switching element 11 and the diode element 13, and the positive electrode P side of the power supply voltage, or the negative electrode N side. In the present embodiment, the bus bar 25 is arranged in a state substantially parallel to the base plate 21, the insulating substrate 23, the switching element 11, and the diode element 13.

  A connecting member 31 is provided so as to electrically connect the switching element 11 and the diode element 13 to the bus bar 25. The connection member 31 is a plate-like member having conductivity, and is made of a metal material such as copper or aluminum, for example. The connection member 31 connects the conductor connection part 33 connected to the bus bar 25, the element connection part 35 connected to the switching element 11 and the diode element 13, and the conductor connection part 33 and the element connection part 35. And a connecting portion 37 to be configured. In the present embodiment, one connection member 31 is configured to connect one switching element 11 and one diode element 13 to one bus bar 25 in common.

  In order to realize such a configuration, in the present embodiment, the connection member 31 includes a first element connection portion 35 a connected to the switching element 11 and a second element connection portion 35 b connected to the diode element 13. And a conductor connecting portion 33 that is interposed between the first element connecting portion 35a and the second element connecting portion 35b and integrally connects the two element connecting portions 35a and 35b. Further, the conductor connecting portion 33 and the first element connecting portion 35a are connected by the first connecting portion 37a, and the conductor connecting portion 33 and the second element connecting portion 35b are connected by the second connecting portion 37b. In this example, the connection member 31 is formed by bending one substantially plate-like plate member having a substantially constant width. And the connection member 31 is comprised by the conductor connection part 33, the 1st element connection part 35a, the 2nd element connection part 35b, the 1st connection part 37a, and the 2nd connection part 37b.

  The conductor connecting portion 33 is arranged so that the upper surface thereof is in contact with the lower surface of the bus bar 25 substantially in parallel and is connected to the bus bar 25. Further, the first element connection portion 35 a is arranged so that the lower surface thereof is in contact with the upper surface of the switching element 11 and is connected to the switching element 11. Similarly, the second element connection portion 35 b is arranged so that the lower surface thereof is in contact with the upper surface of the diode element 13 and is connected to the diode element 13. The conductor connecting portion 33 and the bus bar 25 are joined by laser welding. Details will be described later. The first element connection portion 35a and the switching element 11, and the second element connection portion 35b and the diode element 13 are fixed by solder.

  Here, in the present embodiment, the connection member 31 is configured to have a shape in which a cross-sectional shape in a plane orthogonal to the Y axis is bent into a substantially U shape in a portion corresponding to each of the elements 11 and 13. Has been. In this example, the connecting portions 37a and 37b have a linear cross-sectional shape, and the cross-sectional shape of the connecting member 31 is an angular U-shape (substantially U-shape). Corresponding to the bus bar 25, the switching element 11, and the diode element 13 being arranged substantially in parallel to each other, the conductor connecting portion 33 and the element connecting portion 35 are also arranged to be substantially parallel to each other. In this example, both the part which connects the bus-bar 25 and the switching element 11 and the part which connects the bus-bar 25 and the diode element 13 among the connection members 31 have a substantially U-shaped cross-sectional shape. . The connecting member 31 is configured to have a certain width in the Y-axis direction. In this example, the connecting member 31 and the bus bar 25 have the same width in the Y-axis direction.

  Specifically, in the connection member 31, the conductor connection portion 33 and the first element connection portion 35 a that are arranged substantially parallel to each other are connected to one side in the X-axis direction at the portion connecting the bus bar 25 and the switching element 11. (The left side in FIG. 2), the respective end portions are arranged at the same position in the X-axis direction, and the end portions on one side in the X-axis direction are connected in the Z-axis direction by the first connecting portion 37a. Thus, a substantially U-shaped cross-sectional shape is formed. Further, in the connection member 31, at the portion connecting the bus bar 25 and the diode element 13, the conductor connection portion 33 and the second element connection portion 35 b arranged substantially parallel to each other are provided on the other side in the X-axis direction (FIG. 2). The right ends of the X-axis direction are arranged with their ends aligned, and the other ends of the X-axis directions are connected to each other in the Z-axis direction by the second connecting portions 37b. A U-shaped cross-sectional shape is formed. As described above, the conductor connecting portion 33 integrally connects the two element connecting portions 35a and 35b, and the cross-sectional shape of the connecting member 31 as a whole is substantially the same from both ends of the conductor connecting portion 33 in the X-axis direction. The shape is folded in a U shape.

  In the connection member 31 configured to have such a shape, as shown in FIGS. 2 to 4, the conductor in a plan view viewed from a direction (Z-axis direction) orthogonal to the bus bar 25 and the conductor connection portion 33. The connection part 33 and the element connection part 35 have an overlapping region D where they overlap each other. In this example, the conductor connecting portion 33 and the first element connecting portion 35a, and the conductor connecting portion 33 and the second element connecting portion 35b have overlapping regions D that overlap each other.

And in the said overlap area | region D, the bus-bar 25 and the conductor connection part 33 are joined by laser welding. Laser welding is performed by irradiating a laser beam L in the Z-axis direction from the upper surface side of the bus bar 25 to the overlapping region D of the conductor connecting portion 33 and the element connecting portions 35a and 35b. As a laser used for such laser welding, for example, a welding laser such as a YAG laser, a CO ₂ laser, or a semiconductor laser can be used. In this example, a YAG laser is used. In laser welding, a very small spot is intensively heated in a short time by using a heat source having a high energy density, so that the heat-affected area can be narrowed and welding with less distortion can be performed. The bus bar 25 and the conductor connection portion 33 are joined via the plurality of melting spots 41 by laser welding. Note that the maximum capacity of the current flowing between the bus bar 25 and the connecting member 31 is determined according to the number of the melting spots 41 and the total area of the melting spots 41 associated therewith.

  By the way, when it is mounted and used in a vehicle like the inverter device 7 including the switching module 8 according to the present embodiment, it is firmly joined to ensure high strength against vibration, and can be reduced in size and size. It is desirable to reduce the weight. Therefore, the connection member 31 is formed of a plate-like member as in the present embodiment, and the melting spot 41 formed across the bus bar 25 and the conductor connection portion 33 of the connection member 31 digs deeply into the conductor connection portion 33. In some cases, the intensity of the laser beam L and the irradiation time are set. In such a case, the laser beam L completely penetrates the conductor connection portion 33 and irradiates the switching element 11 and the diode element 13 due to manufacturing variations of the bus bar 25 and the connection member 31. It may be done. If the switching element 11 or the diode element 13 is directly irradiated with the laser light L, the switching element 11 or the diode element 13 may be thermally damaged.

  In this regard, in the switching module 8 according to the present embodiment, the cross-sectional shape of the connection member 31 is generally folded back from both ends in the X-axis direction of the conductor connection portion 33 into a substantially U shape. And the first element connecting portion 35a, and the conductor connecting portion 33 and the second element connecting portion 35b have overlapping regions D that overlap each other. And in the said duplication area | region D, the bus-bar 25 and the conductor connection part 33 are joined by laser welding. Therefore, even if the laser beam L completely penetrates the conductor connecting portion 33 when performing laser welding by irradiating the laser beam L in the Z-axis direction from the upper surface side of the bus bar 25, the first element connection The part 35a or the second element connection part 35b shields the direct irradiation of the laser light L to the switching element 11 and the diode element 13. Therefore, it can suppress that the switching element 11 and the diode element 13 receive a thermal damage.

  Further, the first element connecting portion 35a and the second element connecting portion 35b are configured such that radiant heat when the bus bar 25 and the conductor connecting portion 33 are joined by laser welding is conducted to the switching element 11 and the diode element 13 side. It also functions as a shield. Therefore, it can suppress that the switching element 11 and the diode element 13 receive a thermal damage also from this point. That is, the element connection portions 35a and 35b overlapping with the conductor connection portion 33 in a plan view as viewed from the Z-axis direction function as shielding means against the laser light L and the radiant heat, thereby directly to the switching element 11 and the diode element 13. Both manual and indirect thermal damage are suppressed.

  Further, if it is within the overlapping region D, direct irradiation of the laser light L to the switching element 11 and the diode element 13 is shielded by the first element connecting portion 35a and the second element connecting portion 35b, so that from the Z-axis direction. Even in a region overlapping the switching element 11 and the diode element 13 in a plan view as seen, the bus bar 25 and the conductor connection portion 33 can be joined by laser welding. Therefore, it is not necessary to secure a separate space for laser welding. For example, as shown in FIG. 11 showing the prior art, the conductor plate 103 and the portion other than the portion directly above the semiconductor element 101 such as a switching element or a diode element are used. Compared with the case where the metal plate 102 is connected, the distance between the switching element 11 and the diode element 13 in the X-axis direction can be shortened. Therefore, the switching module 8 can be reduced in size, and as a result, the entire inverter device 7 can also be reduced in size.

  Furthermore, since the number of welding spots 41 (total area of the welding spots 41) by laser welding can be set relatively freely within the overlapping region D, the connection member 31 can be secured by ensuring a large amount of these spots. The energization amount between the interposed bus bar 25 and the switching element 11 and the diode element 13 can be increased. Note that the size of the overlapping region D can be adjusted by appropriately changing the length of the conductor connecting portion 33, the first element connecting portion 35a, and the second element connecting portion 35b along the X-axis direction. . Or it can also adjust by changing suitably the width | variety of these Y-axis directions.

[Second Embodiment]
A second embodiment of the present invention will be described with reference to the drawings. Also in this embodiment, the present invention is applied to the switching module 8 constituting the inverter device 7 for controlling the rotating electrical machine 3. FIG. 5 is a cross-sectional view of the switching module 8 according to the present embodiment. The switching module 8 according to the present embodiment is partially different from the first embodiment in the structure of the connection member 31. Other configurations are basically the same as those in the first embodiment. Below, the switching module 8 which concerns on this embodiment is demonstrated centering on difference with said 1st embodiment. Note that points not particularly specified are the same as those in the first embodiment.

  In the present embodiment, the connection member 31 is configured to have a shape in which a cross-sectional shape in a plane perpendicular to the Y axis is bent in a substantially Z shape in a portion corresponding to each of the elements 11 and 13. . Corresponding to the bus bar 25, the switching element 11, and the diode element 13 being arranged substantially in parallel to each other, the conductor connecting portion 33 and the element connecting portion 35 are also arranged to be substantially parallel to each other. In this example, both the part which connects the bus-bar 25 and the switching element 11, and the part which connects the bus-bar 25 and the diode element 13 among the connection members 31 have a substantially Z-shaped cross-sectional shape. .

  Specifically, in the connection member 31, the conductor connection portion 33 and the first element connection portion 35 a that are arranged substantially parallel to each other are connected to one side in the X-axis direction at the portion connecting the bus bar 25 and the switching element 11. (Left side in FIG. 5), the respective end portions are arranged with their positions in the X-axis direction aligned. An end portion on one side in the X-axis direction of the conductor connection portion 33 and an end portion on the other side (right side in FIG. 5) in the X-axis direction of the first element connection portion 35a are inclined by the first connecting portion 37a. They are connected to form a substantially Z-shaped cross-sectional shape. Further, in the connection member 31, the conductor connection portion 33 and the second element connection portion 35 b that are arranged substantially parallel to each other are connected to each other on the other side in the X-axis direction at the portion connecting the bus bar 25 and the diode element 13. The end portions are arranged with their positions in the X-axis direction aligned. Then, the other end portion in the X-axis direction of the conductor connecting portion 33 and the one end portion in the X-axis direction of the second element connecting portion 35b are connected in an oblique direction by the second connecting portion 37b, and approximately Z A letter-shaped cross-sectional shape is formed. The conductor connecting portion 33 integrally connects the two element connecting portions 35a and 35b, and the cross-sectional shape of the connecting member 31 is substantially Z-shaped from both ends of the conductor connecting portion 33 in the X-axis direction as a whole. The shape is folded back.

  Even in the connection member 31 configured to have such a shape, as shown in FIG. 5, the conductor connection portion 33 in a plan view viewed from a direction (Z-axis direction) orthogonal to the bus bar 25 and the conductor connection portion 33. And the element connecting portions 35a and 35b have overlapping regions D that overlap each other. And in the said overlap area | region D, the bus-bar 25 and the conductor connection part 33 are joined by laser welding.

  In the switching module 8 according to the present embodiment, the first connecting portion 37a and the second connecting portion 37b constituting the connecting member 31 extend over the entire overlap region D. Therefore, in the present embodiment, in addition to the element connecting portions 35a and 35b, the connecting portions 37a and 37b also function as shielding means against the laser light L and the radiant heat. Therefore, both direct and indirect thermal damage to the switching element 11 and the diode element 13 are further effectively suppressed as compared with the case of the first embodiment. Note that, under the condition that the conductor connecting portion 33 and the element connecting portions 35a and 35b have the same length in the X-axis direction, the length of the entire connecting member 31 is longer in the present embodiment than in the first embodiment. Become. Therefore, since the heat capacity of the connecting member 31 is increased, the amount of heat conducted to the switching element 11 and the diode element 13 through the connecting member 31 can be reduced. Moreover, since the surface area of the connection member 31 becomes large, heat dissipation is also improved. Therefore, thermal damage to the switching element 11 and the diode element 13 can be suppressed also from this point. In addition, it is also possible to reduce the thickness of the connecting member 31 while ensuring the shielding property, thereby reducing the weight.

  In the structure of the connection member 31 according to the present embodiment, the conductor connection portion 33, the first element connection portion 35a, and the second element connection portion 35b are substantially parallel by changing the bending angle at each bent portion. The relative positional relationship between these can be elastically changed while maintaining the state. Therefore, even if the distance between the switching element 11 or the diode element 13 and the bus bar 25 has some variation (tolerance) due to a manufacturing error, the conductor connection portion 33, the first element connection portion 35 a, The variation (tolerance) can be absorbed by displacing the positional relationship between the two-element connecting portion 35b. In addition, even when the inverter device 7 including the switching module 8 according to the present embodiment is often used in a place where the vibration is likely to occur because it is mounted on a vehicle, the conductor connecting portion absorbs the vibration. The stress applied to the junction between 33 and the bus bar 25, the junction between the first element connecting portion 35a and the switching element 11, and the connection between the second element connecting portion 35b and the diode element 13 are as follows. Can be reduced. Therefore, even when used in a place with such a lot of vibration, the electrical connection between them can be appropriately maintained. In this way, the reliability of the inverter device 7 including the switching module 8 is improved.

[Third embodiment]
A third embodiment of the present invention will be described with reference to the drawings. Also in this embodiment, the present invention is applied to the switching module 8 constituting the inverter device 7 for controlling the rotating electrical machine 3. FIG. 6 is a cross-sectional view of the switching module 8 according to the present embodiment. The switching module 8 according to the present embodiment is partially different from the first and second embodiments in the structure of the connection member 31. Other configurations are basically the same as those in the first and second embodiments. Below, the switching module 8 which concerns on this embodiment is demonstrated centering on difference with said 1st and 2nd embodiment. Note that the points not particularly specified are the same as those in the first and second embodiments.

  In the present embodiment, the conductor connecting portion 33 and the element connecting portions 35a and 35b constituting the connecting member 31 are disposed substantially parallel to each other, and the connecting portions 37a and 37b are connected to the conductor connecting portion 33 and the element connecting portion 35a, It can be elastically deformed in the direction (Z-axis direction) orthogonal to 35b. More specifically, the connecting portions 37a and 37b have a cross-sectional shape that is curved inward (in a direction close to each other) from both end portions in the X-axis direction of the conductor connecting portion 33. At this time, the bending angle between the conductor connecting portion 33 and the connecting portions 37a and 37b and the bending angle between the element connecting portions 35a and 35b and the connecting portions 37a and 37b are preferably 30 to 60 °, for example. It is. In the illustrated example, the angle is about 45 °. The connecting portions 37a and 37b having such a shape can absorb stress applied in the Z-axis direction by elastic deformation.

  That is, in the structure of the connecting member 31 according to the present embodiment, the conductor connecting portion 33, the first element connecting portion 35a, and the second element connecting portion 35b are substantially parallel by elastically deforming the connecting portions 37a and 37b themselves. The relative positional relationship between them can be changed while maintaining the state. Therefore, also in the switching module 8 according to the present embodiment, the positional relationship between the conductor connection portion 33 and the first element connection portion 35a and the second element connection portion 35b is displaced, so that the switching element 11 and the diode element 13 Variations (tolerances) in the distance from the bus bar 25 can be absorbed. Moreover, the vibration transmitted to the switching module 8 is absorbed, the junction location between the conductor connection part 33 and the bus bar 25, the junction location between the first element connection part 35a and the switching element 11, and the second element connection part. The stress applied to the connection point between 35b and the diode element 13 can be reduced. Therefore, even when used in a place with a lot of vibrations, the electrical connection between them can be appropriately maintained, so that the reliability of the inverter device 7 including the switching module 8 can be improved.

[Other Embodiments]
(1) In the first embodiment described above, the connection member 31 is described as an example in which the connection member 31 has a shape in which a cross-sectional shape in a plane perpendicular to the Y axis is bent in a substantially U shape. did. However, the embodiment of the present invention is not limited to this. That is, for example, as shown in FIG. 7, the connection member 31 may have a configuration in which a cross-sectional shape in a plane orthogonal to the X axis is bent in a substantially U shape. one of. In this case, the 1st connection part 37a and the 2nd connection part 37b may be arrange | positioned in the same position in the Y-axis direction, and may be arrange | positioned in a different position. In FIG. 7, the first connecting portion 37 a connects the conductor connecting portion 33 and the switching element 11 at one end in the Y-axis direction (the right side in FIG. 7B), and the second connecting portion 37 b An example is shown in which the conductor connecting portion 33 and the diode element 13 are connected at the other end in the Y-axis direction (left side in FIG. 7B) so that they are arranged at different positions. Yes.

(2) In the second embodiment, the case where the connecting member 31 is configured to have a shape in which a cross-sectional shape in a plane orthogonal to the Y-axis is bent in a substantially Z shape will be described as an example. did. However, the embodiment of the present invention is not limited to this. That is, for example, as shown in FIG. 8, the connection member 31 may have a configuration in which a cross-sectional shape in a plane orthogonal to the X axis is bent in a substantially Z shape. one of. In this case, the first connecting portion 37a and the second connecting portion 37b may be arranged so that the normal vectors face the same direction, or may be arranged so as to face different directions. In FIG. 8, the first connecting portion 37 a has an end portion on the other side in the Y axis direction of the conductor connecting portion 33 (left side in FIG. 8B) and one side in the Y axis direction of the switching element 11 (FIG. 8B). ) And the second connecting portion 37b connects one end portion of the conductor connecting portion 33 in the Y-axis direction and the other end portion of the diode element 13 in the Y-axis direction. Thus, an example in which these normal vectors are arranged so as to face in different directions is shown.

(3) In the first embodiment, the connecting member 31 is configured to have a U-shaped (substantially U-shaped) bent cross-sectional shape in a plane orthogonal to the Y axis. The case has been described as an example. However, the embodiment of the present invention is not limited to this. That is, for example, as shown in FIG. 9, it is also preferable that the connection member 31 has a configuration in which a cross-sectional shape in a plane orthogonal to the Y axis is bent into a rounded U shape. This is one of the embodiments. The same applies to the second embodiment. For example, the connecting member 31 may have a configuration in which a cross-sectional shape in a plane orthogonal to the Y axis is bent into a rounded Z shape. It is one of the preferred embodiments of the invention. In these cases, the same tolerance absorption effect and vibration absorption effect as in the case of the third embodiment can be obtained.

(4) In the third embodiment, the connecting portions 37 a and 37 b of the connecting member 31 are configured to have a cross-sectional shape that curves inward from both ends in the X-axis direction of the conductor connecting portion 33. Thus, the case where these are elastically deformable in the Z-axis direction has been described as an example. However, the embodiment of the present invention is not limited to this. That is, for example, using a coil spring as the connecting portions 37a and 37b so that they can be elastically deformed in the Z-axis direction is also one preferred embodiment of the present invention.

(5) In each of the embodiments described above, the connection member 31 includes the first element connection portion 35a and the second element connection portion 35b, and the conductor connection that integrally connects the two element connection portions 35a and 35b. The case has been described as an example in which the portion 33 is provided and one connection member 31 is configured to connect one switching element 11 and one diode element 13 to one bus bar 25 in common. However, the embodiment of the present invention is not limited to this. That is, for example, as shown in FIG. 10, the switching element 11 and the diode element 13 may be electrically connected to the bus bar 25 by individual connection members 31, respectively. One. FIG. 10 shows an example in which the individual connecting member 31 is configured so that the cross-sectional shape in the plane orthogonal to the Y axis has a square pipe shape. Of course, the individual connection members 31 can be configured to have various shapes as exemplified in the above embodiments.

(6) In each of the above embodiments, the specific shape of the connection member 31 provided in the switching module 8 has been described as an example. However, the embodiment of the present invention is not limited to this. That is, if the conductor connection portion 33 and the element connection portions 35a and 35b have an overlapping region D that overlaps when viewed from the direction (Z-axis direction) orthogonal to the bus bar 25 and the conductor connection portion 33, the conductor connection portion The position and the shape of the connecting portions 37a and 37b for connecting 33 and the element connecting portions 35a and 35b may be arbitrary.

(7) In each of the above embodiments, as an example, the bus bar 25 is arranged in a state substantially parallel to the insulating substrate 23 stacked on the base plate 21, the switching element 11, and the diode element 13. explained. However, the embodiment of the present invention is not limited to this. That is, the bus bar 25 may be disposed in an inclined state with respect to the insulating substrate 23 stacked on the base plate 21, the switching element 11, and the diode element 13. Even in this case, the conductor connection portion 33 is arranged so that the upper surface thereof is in contact with the lower surface of the bus bar 25 substantially in parallel and is connected to the bus bar 25. The first element connection portion 35a is disposed so that its lower surface is in contact with the upper surface of the switching element 11 and is connected to the switching element 11, and the lower surface of the second element connection portion 35b is a diode element. It is disposed so as to be in contact with the upper surface of 13 substantially parallel to the diode element 13.

(8) In each of the above embodiments, the case where the present invention is applied to the switching module 8 constituting the inverter device 7 for controlling the rotating electrical machine 3 provided in the hybrid vehicle has been described as an example. However, the embodiment of the present invention is not limited to this. That is, for example, the present invention can be applied to an inverter device for controlling a rotating electrical machine provided in an electric vehicle. Further, the present invention can be applied not only to a vehicle but also to an inverter device for controlling a rotating electrical machine provided in, for example, a stationary air conditioner facility.

(9) In each of the above embodiments, the case where the present invention is applied to the switching module 8 including the IGBT and FWD as semiconductor elements has been described as an example. However, the embodiment of the present invention is not limited to this. That is, the present invention can be applied to any semiconductor device provided with other elements such as MOSFETs and GTOs (Gate Turn-Off thyristors) as semiconductor elements.

  The present invention electrically connects, for example, at least one semiconductor element such as an inverter device for controlling a rotating electrical machine, a conductor plate serving as an energization path for a current flowing through the semiconductor element, and the semiconductor element and the conductor plate. It can utilize suitably for the semiconductor device provided with the connection member to connect.

8 Switching module (semiconductor device)
11 Switching elements (semiconductor elements)
13 Diode element (semiconductor element)
25 Bus bar (conductor plate)
31 connection member 33 conductor connection part 35 element connection part 35a first element connection part (element connection part)
35b Second element connection part (element connection part)
37 connection part 37a 1st connection part (connection part)
37b 2nd connection part (connection part)
D Overlapping area

Claims (6)

A semiconductor device comprising: at least one semiconductor element; a conductor plate serving as an energization path for current flowing through the semiconductor element; and a connection member that electrically connects the semiconductor element and the conductor plate,
The connection member includes a plate-like conductor connection portion that is in contact with the conductor plate substantially in parallel, and a plate-like element connection portion in contact with the surface on the conductor connection portion side of the semiconductor element,
In a plan view seen from the direction orthogonal to the conductor plate, the conductor connection portion and the element connection portion have an overlapping region overlapping each other,
A semiconductor device in which the conductor plate and the conductor connection portion are joined by laser welding in the overlapping region. The connecting member further includes a connecting portion that connects the conductor connecting portion and the element connecting portion,
2. The conductor connecting portion and the element connecting portion are arranged substantially parallel to each other, and the connecting portion is elastically deformable in a direction perpendicular to the conductor connecting portion and the element connecting portion. Semiconductor device.   The connecting member has a shape obtained by bending a plate-like member into a substantially U-shaped cross section, and one of two surfaces substantially parallel to each other is the conductor connecting portion, and the other is the element connecting portion. The semiconductor device according to claim 1 or 2.   The connecting member has a shape obtained by bending a plate-like member into a substantially Z-shaped cross section, and one of two surfaces substantially parallel to each other is the conductor connecting portion, and the other is the element connecting portion. The semiconductor device according to claim 1 or 2. A plurality of the semiconductor elements are provided, and the connecting member is configured to connect two semiconductor elements in common to the conductor plate,
The connection member includes two element connection portions that respectively contact the two semiconductor elements, and the conductor connection portion is interposed between the two element connection portions, and the two element connection portions are integrated with each other. The semiconductor device as described in any one of Claim 1 to 4 which has connected. A connecting member for electrically connecting at least one semiconductor element and a conductor plate serving as an energization path for a current flowing through the semiconductor element;
A plate-like conductor connecting portion that is substantially parallel to the conductor plate and is joined by laser welding; and a plate-like element connecting portion that is substantially parallel to the surface of the semiconductor element on the side of the conductor connecting portion. Prepared,
A connecting member having an overlapping region where the conductor connecting portion and the element connecting portion overlap each other in a plan view as viewed from a direction orthogonal to the conductor connecting portion.

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