Electric circuit body, electric power conversion device, and electric circuit body manufacturing method

Abstract

This electric circuit body comprises: a first assembly formed by sandwiching an upper arm semiconductor element between a first conductor plate and a second conductor plate in the thickness direction; a second assembly formed by sandwiching a lower arm semiconductor element between a third conductor plate and a fourth conductor plate in the thickness direction; and a sealing material for sealing the first assembly and the second assembly. The first conductor plate and the fourth conductor plate are mechanically and electrically connected at a joined section formed on the sides of the plates that face each other. The first conductor plate and the fourth conductor plate are disposed on a first substantially same plane. The second conductor plate and the third conductor plate are disposed on a second substantially same plane, which differs from the first substantially same plane. The front-rear orientation of the upper arm semiconductor element is the inverse of the front-rear orientation of the lower arm semiconductor element.

Description

Electric circuit body, power conversion device, and method for manufacturing electric circuit body

[0001] The present invention relates to an electric circuit body, a power conversion device, and a method for manufacturing an electric circuit body.

[0002] In recent years, there has been a demand for higher output and higher density in automotive power conversion devices. To achieve both high output and high density, it is necessary to reduce losses and suppress heat generation. One known method for reducing switching losses is to increase the switching speed. However, increasing the switching speed can cause problems such as increased surge voltage. Patent Document 1 discloses a power semiconductor module including a power semiconductor element, a conductor plate electrically connected to the power semiconductor element, a metal case accommodating the power semiconductor element and the conductor plate, a front cover joined to one outer surface of the metal case, a back cover joined to the other outer surface of the metal case, an inlet portion arranged on one side of the metal case, and an outlet portion arranged on the one side of the metal case, wherein the metal case has a first heat dissipation portion and a second heat dissipation portion facing the first heat dissipation portion across the conductor plate, the front cover is arranged at a position facing the first heat dissipation portion so as to form a space for a front side flow path between itself and the first heat dissipation portion, the back cover is arranged at a position facing the second heat dissipation portion so as to form a space for a back side flow path between itself and the second heat dissipation portion, the inlet portion is connected to the front side flow path and the back side flow path, and the outlet portion is connected to the front side flow path and the back side flow path.

[0003] Japanese Patent Application Publication No. 2014-23327

[0004] The invention described in Patent Document 1 leaves room for improvement in productivity and reduction of inductance.

[0005] According to a first aspect of the present invention, an electric circuit body includes a first assembly formed by sandwiching an upper arm semiconductor element between a first conductor plate and a second conductor plate in a thickness direction, a second assembly formed by sandwiching a lower arm semiconductor element between a third conductor plate and a fourth conductor plate in the thickness direction, and a sealing material that seals the first assembly and the second assemblies, wherein the first conductor plate and the fourth conductor plate are mechanically and electrically connected at joints formed on opposing sides, the first conductor plate and the fourth conductor plate are arranged on a first approximately coplanar surface, the second conductor plate and the third conductor plate are arranged on a second approximately coplanar surface different from the first approximately coplanar surface, and the upper arm semiconductor element and the lower arm semiconductor element are in an inverted relationship. According to a second aspect of the present invention, a power conversion device includes one or more of the above-described electric circuits and converts DC power to AC power. A method for manufacturing an electric circuit body according to a third aspect of the present invention includes a first forming step of forming a first assembly by sandwiching an upper arm semiconductor element between a first conductor plate and a second conductor plate in the thickness direction; a second forming step of forming a second assembly by sandwiching a lower arm semiconductor element between a third conductor plate and a fourth conductor plate in the thickness direction; an assembly arranging step of, after the first forming step and the second forming step, arranging the first assembly and the second assemblies so that the first conductor plate and the fourth conductor plate are on a first approximately coplanar surface and the second conductor plate and the third conductor plate are on a second approximately coplanar surface different from the first approximately coplanar surface and so that the upper arm semiconductor element and the lower arm semiconductor element are inverted; and a joining step of mechanically and electrically joining the first conductor plate and the fourth conductor plate.

[0006] According to the present invention, it is possible to suppress an increase in inductance while improving productivity.

[0007] 1. Plan view of an electric circuit body 2. II-II sectional view of an electric circuit body 3. III-III sectional perspective view of an electric circuit body 4. Semi-transparent plan view of a set of upper and lower arms in a semiconductor device 5. Circuit diagram of a set of upper and lower arms in a semiconductor device 6. Semi-transparent plan view of a semiconductor device for comparison 7. Diagrams showing manufacturing processes of a semiconductor device 8. Diagrams showing manufacturing processes of an electric circuit body 9. Diagrams showing manufacturing processes of an electric circuit body 10. Cross-sectional view of a semiconductor device 11. Plan view of an electric circuit body in modified example 12. XII-XII sectional view of an electric circuit body in modified example 13. XIII-XIII sectional perspective view of an electric circuit body in modified example 14. Semi-transparent plan view of a semiconductor device in modified example 15. Diagrams showing manufacturing processes of a semiconductor device in modified example 16. Circuit diagram of a power converter in modified example 27. Perspective view of an external appearance of a power converter 18. XVIII-XVIII sectional view of a power converter 19. Diagram showing the shape of a joint in modified example 4

[0008] First Embodiment An embodiment of an electric circuit body and a method for manufacturing the same will be described below with reference to Figures 1 to 10. The following description and drawings are examples for explaining the present invention, and some omissions and simplifications have been made as appropriate for clarity of explanation. The present invention can also be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0009] The position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. in order to facilitate understanding of the invention. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings. When there are multiple components having the same or similar functions, they may be described using the same reference numeral with different subscripts. However, when it is not necessary to distinguish between these multiple components, the subscripts may be omitted in the description.

[0010] FIG. 1 is a plan view of an electric circuit body 400. In this embodiment, mutually orthogonal X, Y, and Z axes are depicted to clearly show the correlation between the drawings. In FIG. 1, the right side of the figure is the positive side of the X axis, the upper side of the figure is the positive side of the Y axis, and the rear side of the figure is the positive side of the Z axis. The electric circuit body 400 includes a semiconductor device 300 and a cooling member 340. The electric circuit body 400 includes three semiconductor devices 300 having the exact same configuration. Therefore, in the following description, only one of the three semiconductor devices 300 may be designated by a reference numeral. The cooling member 340 includes an upper cooling member 340U on the positive side of the Z axis and a lower cooling member 340L on the negative side of the Z axis.

[0011] The semiconductor device 300 incorporates a first element 155 and a second element 157, which will be described later, and these elements are sealed with a sealing material 360. Terminals connected to the first element 155 and the second element 157 are led out to the positive and negative sides of the Y axis from the sealing material 360 on the side surfaces of the semiconductor device 300. These terminals are power terminals through which a large current flows, such as a positive terminal 315B and a negative terminal 319B connected to a capacitor module 500 (see FIG. 16) of the DC circuit, and an AC terminal 320B connected to a first motor-generator 192 and a second motor-generator 194 (see FIG. 16) of the AC circuit.

[0012] Furthermore, the following signal terminals protrude from the sealing material 360 on the side surface on the positive side of the Y axis of the semiconductor device 300. That is, signal terminals used to control the semiconductor module, such as the lower arm gate terminal 325L, the first mirror emitter signal terminal 325M-1, the second mirror emitter signal terminal 325M-2, the first Kelvin emitter signal terminal 325K-1, the second Kelvin emitter signal terminal 325K-2, and the upper arm gate terminal 325U, protrude from the sealing material 360.

[0013] The electric circuit body 400 functions as a power conversion device that converts DC current and AC current by the switching operation of the first element 155 and the second element 157. The number of semiconductor devices 300 included in the electric circuit body 400 is not limited to three, and can be set arbitrarily to suit various forms of the electric circuit body 400.

[0014] The cooling member 340 is disposed opposite the heat dissipation surface 301 (see FIG. 2 ) of the semiconductor device 300 and cools the heat generated by the switching operation of the first element 155 and the second element 157. Specifically, the cooling member 340 has a flow path formed therein through which a refrigerant flows, and the refrigerant flowing through the flow path cools the heat generated by the semiconductor device 300. The refrigerant may be water or an antifreeze solution made by mixing ethylene glycol with water. The cooling member 340 may be made of a copper-based material, which has high thermal conductivity, or preferably an aluminum-based material, which has even higher thermal conductivity and is lighter than copper. The cooling member 340 may be manufactured by extrusion molding, forging, brazing, or the like.

[0015] Fig. 2 is a cross-sectional view taken along line II-II of the electric circuit body 400 shown in Fig. 1, and Fig. 3 is a cross-sectional perspective view taken along line III-III of the electric circuit body 400 shown in Fig. 1. However, an enlarged view of a bonding portion 330, which will be described later, is shown at the bottom of Fig. 3. The electric circuit body 400 is equipped with a pressure mechanism that clamps and presses the cooling members 340 provided on both sides of the semiconductor device 300 from both sides. Although not shown, the pressure mechanism is, for example, a mechanism that connects the cooling members 340 on both sides with screws or the like and presses them toward the semiconductor device 300.

[0016] As shown in FIG. 2 , the power conversion device 200 includes a first element 155 and a first diode 156 that form an upper arm circuit (see FIGS. 4 and 5 described below). However, the body diode of the first element 155 may be used as the first diode 156. The collector side of the first element 155 is bonded to a second conductor plate 431. This bonding may be performed using solder or sintered metal. The first conductor plate 430 is bonded to the emitter side of the first element 155.

[0017] As shown in Figure 3, the second element 157 is arranged on the positive side of the X-axis of the first element 155. The second element 157 forms a lower arm circuit of the power conversion device 200. The first element 155 is a semiconductor element that forms the upper arm circuit, so it can also be called the "upper arm semiconductor element." The second element 157 is a semiconductor element that forms the lower arm circuit, so it can also be called the "lower arm semiconductor element." Although not shown in Figures 2 and 3, a second diode 158 that forms a lower arm circuit together with the second element 157 is arranged on the positive side of the Y-axis of the second element 157.

[0018] The first element 155 and the second element 157 may be made of Si, SiC, GaN, GaO, C, or the like. The first element 155 and the second element 157 are, for example, power semiconductor elements such as an IGBT (insulated gate bipolar transistor) or a MOSFET (metal oxide semiconductor field effect transistor). When a MOSFET is used as the first element 155 and the second element 157, the first diode 156 and the second diode 158 are not necessary.

[0019] Hereinafter, the first conductor plate 430, the second conductor plate 431, the third conductor plate 432, and the fourth conductor plate 433 will be collectively referred to as conductor plate 435. There are no particular limitations on the material of conductor plate 435 as long as it has high electrical conductivity and thermal conductivity, but it is desirable to use a metallic material such as a copper-based or aluminum-based material, or a composite material of a metallic material and a high thermal conductivity material such as diamond, carbon, or ceramic. These metals may be used alone for conductor plate 435, but plating with Ni, Ag, or the like may be applied to improve bonding with solder or sintered metal.

[0020] As shown in Figures 2 and 3, the conductor plate 435 not only serves to conduct current but also serves as a heat transfer member that transfers heat generated by the first element 155, the second element 157, the first diode 156, and the second diode 158 to the cooling member 340. Because the conductor plate 435 and the cooling member 340 have different potentials, it is desirable to place an upper insulating sheet 440 and a lower insulating sheet 441 between them. The first element 155, the second element 157, the first diode 156, and the second diode 158, the conductor plate 435, the upper insulating sheet 440, and the lower insulating sheet 441 are sealed with a sealing material 360 by transfer molding to form the semiconductor device 300. In order to reduce the contact thermal resistance between the semiconductor device 300 and the cooling member 340, a thermally conductive member 453 is disposed between the semiconductor device 300 and the cooling member 340.

[0021] The upper insulating sheet 440 may include an upper resin insulating layer 442 and an upper metal foil 444. The lower insulating sheet 441 may include a lower resin insulating layer 443 and a lower metal foil 445. The upper resin insulating layer 442 and the lower resin insulating layer 443 are not particularly limited as long as they are adhesive to the heat sink, but an epoxy resin-based resin insulating layer with a powdered inorganic filler dispersed therein is preferred because it provides a good balance between adhesiveness and heat dissipation. The upper insulating sheet 440 and the lower insulating sheet 441 may be resin insulating layers alone, but it is preferred that an upper metal foil 444 and a lower metal foil 445 be provided on the side that contacts the thermal conductive member 453.

[0022] In the transfer molding process, when upper insulating sheet 440 and lower insulating sheet 441 are placed in a mold, release sheets are provided on the surfaces of upper insulating sheet 440 and lower insulating sheet 441 that come into contact with the mold in order to prevent them from adhering to the mold. However, upper metal foil 444 and lower metal foil 445 may be used instead of the release sheets.

[0023] Because the release sheet has low thermal conductivity, a peeling process is required after transfer molding. However, when using the upper metal foil 444 and the lower metal foil 445, by selecting a copper-based or aluminum-based metal with high thermal conductivity, they can be used without peeling after transfer molding. By transfer molding the upper insulating sheet 440 and the lower insulating sheet 441 together, the edges of the upper insulating sheet 440 and the lower insulating sheet 441 are covered with the sealing material 360, which has the effect of improving reliability.

[0024] The thermal conductive member 453 can be made of a material that is fluid at room temperature or high temperatures, such as grease, gel grease, or phase change sheet. However, to ensure workability and long-term reliability, it is desirable to use a curable thermal conductive material for the thermal conductive member 453, which is fluid when uncured and loses its fluidity after curing. Curable thermal conductive materials have the advantage of low viscosity when applied, making them easy to work with, and improving their mechanical properties when cured. Curing can be achieved by heat curing, moisture curing, or ultraviolet curing, but heat curing is desirable for deep curing.

[0025] While the thermal conductive member 453 is not particularly limited as long as it is made of a material with high thermal conductivity, it is preferable to use a highly thermally conductive material such as a metal, ceramic, or carbon-based material in combination with a resin material. This is because the resin material fills the gaps between the highly thermally conductive materials, between the highly thermally conductive material and the cooling member 340, and between the highly thermally conductive material and the upper insulating sheet 440 and the lower insulating sheet 441, thereby reducing contact thermal resistance. The resin material is not particularly limited. Silicone resin, which has a small change in elastic modulus from approximately -40°C to approximately 200°C, is the most desirable resin. Furthermore, an insulating material is preferred for the thermal conductive member 453. This is to prevent a decrease in insulation due to the adhesion of a conductive material near the terminals. The thermal conductivity of the thermal conductive member 453 is approximately 5 to 10 W / (m·K). The thermal conductivity can be measured by measuring the density, specific gravity, and thermal diffusivity of the thermal conductive member 453 and calculating the formula: density x specific gravity x thermal diffusivity.

[0026] Electric circuit body 400 is subjected to a so-called thermal cycle in which heat is repeatedly generated and cooled in response to the switching operations of first element 155 and second element 157. Due to this thermal cycle, thermal conduction member 453 tends to be compressed and flow out of semiconductor device 300 because the thermal expansion coefficients of semiconductor device 300 and cooling member 340 are different.

[0027] As shown in FIG. 3 , the semiconductor device 300 includes a first conductor plate 430 and a fourth conductor plate 433, which are mechanically and electrically connected by a bonding member 331 at a bonding portion 330 formed on the opposing sides of the first conductor plate 430 and the fourth conductor plate 433. The first conductor plate 430 and the fourth conductor plate 433 can also be considered to be connected as a single plate. This allows the first conductor plate 430 and the fourth conductor plate 433 to be arranged on the same plane, while the second conductor plate 431 and the third conductor plate 432 are arranged on another plane, with the semiconductor elements connected in an inverted state. As shown in the lower part of FIG. 3 , the first conductor plate 430 includes a protrusion 330A that protrudes from the negative side of the Z axis toward the positive side of the X axis. The bonding portion 330 is formed by bonding the protrusion 330A of the first conductor plate 430 to the negative surface of the Z axis of the fourth conductor plate 433 with the bonding member 331.

[0028] Solder, sintered metal, or conductive adhesive may be used for the bonding member 331. More preferably, any of solder, sintered metal, and conductive adhesive, which are bonding members with a melting point lower than that of the solder or sintered metal used for bonding members of semiconductor elements, is used for the bonding member 331.

[0029] Fig. 4 is a semi-transparent plan view of a pair of upper and lower arms in semiconductor device 300. Fig. 5 is a circuit diagram of a pair of upper and lower arms in semiconductor device 300. Hereinafter, the circuit constituting the upper arm will be referred to as upper arm circuit body 381 or a "first assembly," and the circuit constituting the lower arm will be referred to as lower arm circuit body 382 or a "second assembly." In Fig. 4, the upper arm circuit body 381 is on the left side of the figure, and the lower arm circuit body 382 is on the right side of the figure.

[0030] As shown in Figures 4 and 5, the positive terminal 315B is output from the collector side of the upper arm circuit and is connected to the positive side of a battery or a capacitor. The upper arm gate terminal 325U is output from the gate of the first element 155 of the upper arm circuit. The negative terminal 319B is output from the emitter side of the lower arm circuit and is connected to the negative side of a battery or a capacitor, or GND. The lower arm gate terminal 325L is output from the gate of the second element 157 of the lower arm circuit. The AC terminal 320B is output from the collector side of the lower arm circuit and is connected to the motor. When the neutral point is grounded, the lower arm circuit is connected to the negative side of the capacitor rather than GND.

[0031] A first conductor plate 430 is disposed on the emitter side of the upper arm circuit, a second conductor plate 431 is disposed on the collector side of the upper arm circuit, a third conductor plate 432 is disposed on the emitter side of the lower arm circuit, and a fourth conductor plate 433 is disposed on the collector side of the lower arm circuit. The first conductor plate 430 and the second conductor plate 431 sandwich the first element 155 and the first diode 156 in the Z-axis direction. The third conductor plate 432 and the fourth conductor plate 433 sandwich the second element 157 and the second diode 158 in the Z-axis direction.

[0032] The first conductor plate 430 and the fourth conductor plate 433 are mechanically and electrically connected via the joint 330. The end face on the positive side of the Z axis of the first conductor plate 430 and the end face on the positive side of the Z axis of the fourth conductor plate 433 have the same Z coordinate. The end face on the negative side of the Z axis of the second conductor plate 431 and the end face on the negative side of the Z axis of the third conductor plate 432 have the same Z coordinate. The first element 155 and the second element 157 are in a reversed relationship rotated around the Y axis. The first element 155 and the second element 157 are semiconductor elements of the same type, but are arranged upside down, so the arrangement of the terminals is reversed and the current flow is also reversed.

[0033] The semiconductor device 300 has a 2-in-1 structure in which two arm circuits, an upper arm circuit and a lower arm circuit, are integrated into a single module. A single semiconductor device 300 may include multiple upper arm circuits and multiple lower arm circuits. In this case, the number of output terminals from the semiconductor device 300 can be reduced, thereby enabling miniaturization.

[0034] 6 is a semi-transparent plan view of a comparative example semiconductor device 300Z. As shown in FIG. 6, an upper arm circuit on the left side of the figure and a lower arm circuit on the right side of the figure are connected between a comparative example first conductor plate 430Z and a comparative example fourth conductor plate 433Z via a comparative example joint 332Z. The comparative example joint 332Z also serves to absorb differences in the Z-direction positions of the comparative example first conductor plate 430Z and the comparative example fourth conductor plate 433Z.

[0035] The comparative example fourth conductor plate 433Z and the comparative example third conductor plate 432Z are connected via a semiconductor element, and the third conductor plate 432 and the negative electrode side terminal 319B are connected via the comparative example connection portion 333Z. In this way, the upper arm circuit constituted by the comparative example first conductor plate 430Z and the comparative example second conductor plate 431Z and the lower arm circuit constituted by the comparative example third conductor plate 432Z and the comparative example fourth conductor plate 433Z are connected with their respective semiconductor elements facing the same front and back.

[0036] Compared to this comparative example semiconductor device 300Z, the above-described semiconductor device 300 has the following advantages. First, in the semiconductor device 300, the negative terminal 319B and the third conductor plate 432 are integrated, eliminating the need for the comparative example connection portion 333Z as in the comparative example. As a result, the current path in the semiconductor device 300 is shorter than that in the comparative example semiconductor device 300Z, which is expected to have the effect of reducing inductance. Second, in the semiconductor device 300, the currents flowing through the semiconductor elements of the upper arm circuit and the lower arm circuit are in opposite directions, which is expected to have the effect of reducing inductance.

[0037] 7 to 9 are diagrams illustrating a method for manufacturing the electric circuit body 400. The method for manufacturing the electric circuit body 400 includes a first forming step, a second forming step, an assembly arrangement step, a sheet arrangement step, a transfer molding step, and a bonding step. FIG. 7 is a diagram illustrating a method for manufacturing the semiconductor device 300. Specifically, FIG. 7 is a plan view illustrating the solder connection step and wire bonding step of the upper arm circuit body 381 and the lower arm circuit body 382 of the semiconductor device 300.

[0038] 7A shows a first forming step for manufacturing the upper arm circuit body 381. First, the collector side of the first element 155 and the cathode side of the first diode 156 are connected to the second conductor plate 431. Next, the upper arm gate terminal 325U, the mirror emitter signal terminal 325M, and the Kelvin emitter signal terminal 325K are each connected to the first element 155 by wire bonding. Furthermore, the emitter side of the first element 155 and the anode side of the first diode 156 are connected to the first conductor plate 430 to complete the upper arm circuit body.

[0039] 7B shows a second forming step for manufacturing the lower arm circuit body 382. As in the manufacturing step for the upper arm circuit body 381, first, the collector side of the second element 157 and the cathode side of the second diode 158 are connected to the fourth conductor plate 433. Next, the lower arm gate terminal 325L, the mirror emitter signal terminal 325M, and the Kelvin emitter signal terminal 325K are each connected to the second element 157 by wire bonding. Furthermore, the emitter side of the second element 157 and the anode side of the second diode 158 are connected to the third conductor plate 432 to manufacture the lower arm circuit body 382. Note that the order of the steps shown in FIGS. 7A and 7B may be reversed.

[0040] After the step shown in FIG. 7( b), the lower arm circuit body 382 shown in FIG. 7( b) is flipped over as shown in FIG. 7( c). FIG. 7( d) shows the assembly placement step. As shown in FIG. 7( d), the upper arm circuit body 381 shown in FIG. 7( a) and the lower arm circuit body 382 shown in FIG. 7( c) are placed. At this time, the first element 155 and the second element 157 are in an inverted relationship. Furthermore, as will be shown later in FIG. 10, the first conductor plate 430 and the fourth conductor plate 433 are on a first substantially coplanar plane extending in the XY plane, and the second conductor plate 431 and the third conductor plate 432 are on a second substantially coplanar plane extending in the XY plane. A joining member 331 is arranged at the joint 330, but at this stage, the first conductor plate 430 and the fourth conductor plate 433 may be joined using the joining member 331, such as solder, sintered metal, or conductive adhesive, or the first conductor plate 430 and the fourth conductor plate 433 may not yet be actively joined, as they will be joined in the transfer molding process shown in Figures 8(c) and 8(d).

[0041] 8 and 9 are cross-sectional views illustrating the manufacturing process of the electric circuit body 400. The same viewpoint as that of FIG. 2 is used in FIGS. 8 and 9. The electric circuit body 400 is manufactured by going through the steps from FIG. 8(a) to FIG. 9(c) in order. The first FIG. 8(a) shows the semiconductor device 300 shown in FIG. 7(d). In other words, FIG. 8(a) is a view obtained by changing the viewpoint of FIG. 7(d).

[0042] FIG. 8(b) shows the placement process, and FIGS. 8(c) and 8(d) show the transfer molding process. In FIG. 8(b), the semiconductor device 300 shown in FIG. 8(a) is placed in a transfer molding device 601, and an upper insulating sheet 440 and a lower insulating sheet 441 are further placed so as to sandwich the semiconductor device 300 from both sides of the Z axis. The transfer molding device 601 includes a spring 602, an upper mold 603U, and a lower mold 603L. The transfer molding device 601 also includes a mechanism for vacuum-adsorbing the upper insulating sheet 440 and the lower insulating sheet 441, and a vacuum degassing mechanism.

[0043] 8(b), the semiconductor device 300 is temporarily placed between an upper mold 603U and a lower mold 603L that have been preheated to a constant temperature of 175°C, and the upper insulating sheet 440 and the lower insulating sheet 441 are held by vacuum suction. The semiconductor device 300 has been preheated to 175°C, and is disposed between the upper mold 603U and the lower mold 603L at a position away from the upper insulating sheet 440 and the lower insulating sheet 441.

[0044] Next, as shown in FIG. 8( c), the upper mold 603U and the lower mold 603L are clamped together. The space between the upper mold 603U and the lower mold 603L after clamping is called the "mold cavity" 610. At this time, the springs 602 pressurize the upper insulating sheet 440 and the lower insulating sheet 441 and the first conductive plate 430 and the second conductive plate 431, causing them to adhere tightly to each other. Next, the mold cavity 610 is evacuated to a predetermined pressure or less. Once evacuation is complete, the upper mold 603U and the lower mold 603L are further compressed to completely clamp them. At this time, the upper insulating sheet 440 and the lower insulating sheet 441 come into contact with the semiconductor device 300. The upper insulating sheet 440 and the lower insulating sheet 441 come into contact with the semiconductor device 300 in a vacuum state, and are then adhered to each other by the pressure of the springs 602, allowing for adhesion without the formation of voids.

[0045] Then, as shown in Fig. 8(d), sealing material 360 is injected into the mold cavity. The peripheral edges of upper insulating sheet 440 and lower insulating sheet 441 are buried in sealing material 360. In the transfer molding process shown in Fig. 8(c) and Fig. 8(d), the bonding member 331 is subjected to high temperature and pressure, so the first conductive plate 430 and the fourth conductive plate 433 are bonded by bonding member 331 such as solder, sintered metal, or conductive adhesive.

[0046] Then, as shown in FIG. 9( a), the semiconductor device 300 encapsulated with the encapsulant 360 is removed from the transfer molding device 601 and post-cured at 175°C for at least two hours. Then, as shown in FIG. 9( b), a coating process is performed in which a thermally conductive member 453 is applied to the cooling member 340. Note that the thermally conductive members 453 are shown at the top and bottom of FIG. 9( b), but are given the same reference numeral because they are made of the same material. To emphasize that they are located in different positions, they can also be referred to as the "first thermally conductive member" and the "second thermally conductive member." Finally, the adhesion and curing process is shown in FIG. 9( c). In this adhesion and curing process, the cooling member 340 coated with the thermally conductive member 453 is brought into close contact with the semiconductor device 300. The cooling member 340 is then pressed against the semiconductor device 300 via the thermally conductive member 453, and the thermally conductive member 453 is cured, thereby producing the electric circuit body 400.

[0047] FIG. 10 is a cross-sectional view of the semiconductor device 300. FIG. 10 is viewed from approximately the same perspective as FIG. 3, and for convenience of drawing, the upper insulating sheet 440, the lower insulating sheet 441, and the sealing material 360 are omitted. The central coordinate of the first conductor plate 430 projected onto the Z axis is referred to as the first conductor plate central coordinate Zc1. The central coordinate of the second conductor plate 431 projected onto the Z axis is referred to as the second conductor plate central coordinate Zc2. The central coordinate of the third conductor plate 432 projected onto the Z axis is referred to as the third conductor plate central coordinate Zc3. The central coordinate of the fourth conductor plate 433 projected onto the Z axis is referred to as the fourth conductor plate central coordinate Zc4. The central coordinate of the first element 155 projected onto the Z axis is referred to as the first element central coordinate Zs1. The central coordinate of the second element 157 projected onto the Z axis is referred to as the second element central coordinate Zs2.

[0048] The Z-axis coordinate of the end face on the positive side of the Z axis of the first conductor plate 430 and the Z-axis coordinate of the end face on the positive side of the Z axis of the fourth conductor plate 433 are the same value, which is the upper end face coordinate Z2. The Z-axis coordinate of the end face on the negative side of the Z axis of the second conductor plate 431 and the Z-axis coordinate of the end face on the negative side of the Z axis of the third conductor plate 432 are the same value, which is the lower end face coordinate Z1.

[0049] The first conductor plate 430, the first element 155, and the second conductor plate 431 are aligned in the Z-axis direction, and therefore, from the negative side of the Z-axis to the positive side of the Z-axis, they are aligned in the following order: bottom end coordinate Z1, second conductor plate center coordinate Zc2, first element center coordinate Zs1, first conductor plate center coordinate Zc1, and top end coordinate Z2. Similarly, the fourth conductor plate 433, the second element 157, and the third conductor plate 432 are aligned in the Z-axis direction, and therefore, from the negative side of the Z-axis to the positive side of the Z-axis, they are aligned in the following order: bottom end coordinate Z1, third conductor plate center coordinate Zc3, second element center coordinate Zs2, fourth conductor plate center coordinate Zc4, and top end coordinate Z2.

[0050] The first conductor plate center coordinate Zc1 and the fourth conductor plate center coordinate Zc4 are substantially the same. Therefore, it can be said that the first conductor plate 430 and the fourth conductor plate 433 are arranged on a first substantially coplanar surface. The second conductor plate center coordinate Zc2 and the third conductor plate center coordinate Zc3 are substantially the same. Therefore, it can be said that the second conductor plate 431 and the third conductor plate 432 are arranged on a second substantially coplanar surface.

[0051] The first embodiment described above provides the following advantageous effects. (1) The electric circuit body 400 includes an upper arm circuit body 381 formed by sandwiching the first element 155 between the first conductor plate 430 and the second conductor plate 431 in the Z-axis direction, a lower arm circuit body 382 formed by sandwiching the second element 157 in the Z-axis direction between the third conductor plate 432 and the fourth conductor plate 433, and a sealing material 360 that seals the upper arm circuit body 381 and the lower arm circuit body 382. The first conductor plate 430 and the fourth conductor plate 433 are mechanically and electrically connected at joints 330 formed on opposing sides. The first conductor plate 430 and the fourth conductor plate 433 are arranged on a first substantially coplanar surface. The second conductor plate 431 and the third conductor plate 432 are arranged on a second substantially coplanar surface different from the first substantially coplanar surface. The first element 155 and the second element 157 are in an inverted relationship. As a result, the current path of the semiconductor device 300 is shorter than that of the comparative example semiconductor device 300Z, which is expected to have the effect of reducing inductance. Furthermore, in the semiconductor device 300, the currents flowing through the semiconductor elements of the upper arm circuit and the lower arm circuit are in opposite directions, which is expected to have the effect of reducing inductance. In addition, the small number of joints makes it easy to manufacture.

[0052] (2) The upper arm gate terminal 325U that controls the first element 155 and the lower arm gate terminal 325L that controls the second element 157 are integrally formed with the first conductor plate 430, the second conductor plate 431, the third conductor plate 432, and the fourth conductor plate 433 by the sealing material 360.

[0053] (3) The end face of the first conductor plate 430 opposite the first element 155 and the end face of the fourth conductor plate 433 opposite the second element 157 are positioned at the upper end face coordinate Z2 in the Z-axis direction. The end face of the second conductor plate 431 opposite the first element 155 and the end face of the third conductor plate 432 opposite the second element 157 are positioned at the lower end face coordinate Z1 in the Z-axis direction. Therefore, the semiconductor device 300 can be easily cooled by being sandwiched from both sides along the Z-axis.

[0054] (4) The joint 330 is a material joint, specifically, a joint using a solder material or a conductive adhesive, so that the joint 330 has excellent conductivity and bonding properties.

[0055] (5) At least one of the first conductive plate 430 and the fourth conductive plate 433 has a protrusion 330A that protrudes toward the other on the side facing the other, and the protrusion 330A forms the joint 330. Therefore, the first conductive plate 430 and the fourth conductive plate 433 can be firmly joined using the protrusion 330A.

[0056] (6) Electric circuit body 400 includes upper cooling member 340U that contacts first conductor plate 430 and fourth conductor plate 433 via at least heat conduction member 453, and lower cooling member 340L that contacts second conductor plate 431 and third conductor plate 432 via at least heat conduction member 453. Therefore, heat generated by first element 155 and second element 157 can be efficiently dissipated using upper cooling member 340U and lower cooling member 340L.

[0057] (7) The thermal conductivity of the heat conducting member 453 is 5 to 10 W / (m·K).

[0058] (8) The electrical circuit body 400 includes an upper cooling member 340U that contacts the first conductor plate 430 and the fourth conductor plate 433 via a heat conduction member 453 and an upper insulating sheet 440, and a lower cooling member 340L that contacts the second conductor plate 431 and the third conductor plate 432 via a heat conduction member 453 and a lower insulating sheet 441.

[0059] (9) The manufacturing method of the electric circuit body 400 includes a first forming step, a second forming step, an assembly arrangement step, and a joining step. In the first forming step, as shown in FIG. 7( a), the upper arm circuit body 381 is formed by sandwiching the first element 155 in the Z-axis direction between a first conductor plate 430 and a second conductor plate 431. In the second forming step, as shown in FIG. 7( b), the lower arm circuit body 382 is formed by sandwiching the second element 157 in the thickness direction between a third conductor plate 432 and a fourth conductor plate 433. 7( d ), after the first and second forming steps, the upper arm circuit body 381 and the lower arm circuit body 382 are arranged so that the first conductor plate 430 and the fourth conductor plate 433 are on a first substantially coplanar plane, the second conductor plate 431 and the third conductor plate 432 are on a second substantially coplanar plane, and the first element 155 and the second element 157 are reversed. In the joining step, the first conductor plate 430 and the fourth conductor plate 433 are mechanically and electrically joined. This facilitates the manufacture of the electric circuit body 400 and reduces inductance.

[0060] (10) The manufacturing method of the electric circuit body 400 includes a sheet arrangement process in which the upper insulating sheet 440 and the lower insulating sheet 441 are arranged so as to sandwich the first substantially coplanar surface and the second substantially coplanar surface, and a sealing material formation process in which the upper mold 603U and the lower mold 603L are arranged so as to cover the upper insulating sheet 440 and the lower insulating sheet 441, and the sealing material 360 is injected into the mold cavity 610 while the upper insulating sheet 440 and the lower insulating sheet 441 are pressurized using the upper mold 603U and the lower mold 603L.

[0061] (11) In the assembly arrangement process, a solder material or a conductive adhesive is placed between the first conductive plate 430 and the fourth conductive plate 433. The sealing material formation process also serves as a bonding process. Therefore, the bonding process can be eliminated.

[0062] (Modification 1) Fig. 11 is a plan view of an electric circuit body 400A in Modification 1. Fig. 11 corresponds to Fig. 1 in the above-described embodiment. The electric circuit body 400A includes three semiconductor devices 300A connected in parallel and cooling members 340 that sandwich the semiconductor devices 300A from both sides of the Z axis.

[0063] Fig. 12 is a cross-sectional view taken along line XII-XII of the electric circuit body 400A shown in Fig. 11, and Fig. 13 is a cross-sectional perspective view taken along line XIII-XIII of the electric circuit body 400A shown in Fig. 12. Fig. 14 is a semi-transparent plan view of the semiconductor device 300A. That is, Figs. 11 to 14 correspond to Figs. 1 to 4 in the embodiment.

[0064] As shown in FIG. 13 , the positive terminal 315B is output from the collector side of the upper arm circuit and is connected to the positive side of a battery or a capacitor. The upper arm gate terminal 325U is output from the gate of the first element 155 of the upper arm circuit. The negative terminal 319B is output from the emitter side of the lower arm circuit and is connected to the negative side of a battery or a capacitor, or GND. The lower arm gate terminal 325L is output from the gate of the second element 157 of the lower arm circuit. The AC terminal 320B is output from the collector side of the lower arm circuit and is connected to the motor. When the neutral point is grounded, the lower arm circuit is connected to the negative side of the capacitor rather than GND.

[0065] Similar to the embodiment, a first conductor plate 430 is disposed on the emitter side of the upper arm circuit, a second conductor plate 431 is disposed on the collector side of the upper arm circuit, a third conductor plate 432 is disposed on the emitter side of the lower arm circuit, and a fourth conductor plate 433 is disposed on the collector side of the lower arm circuit. That is, in this modification, the first conductor plate 430 and the second conductor plate 431 also sandwich the first element 155 and the first diode 156 in the Z-axis direction. Furthermore, the third conductor plate 432 and the fourth conductor plate 433 sandwich the second element 157 and the second diode 158 in the Z-axis direction.

[0066] The first conductor plate 430 and the fourth conductor plate 433 are mechanically and electrically connected via the joint 330. The end face on the positive side of the Z axis of the first conductor plate 430 and the end face on the positive side of the Z axis of the fourth conductor plate 433 have the same Z axis coordinate. The end face on the negative side of the Z axis of the second conductor plate 431 and the end face on the negative side of the Z axis of the third conductor plate 432 have the same Z axis coordinate. The first element 155 and the second element 157 are reversed when rotated around the Y axis.

[0067] FIG. 15 is a diagram illustrating a manufacturing method of the semiconductor device 300A, and corresponds to FIG. 7 of the embodiment. FIG. 15(a) shows the soldering process and wire bonding process for the upper arm circuit. The main difference between FIG. 15 and FIG. 7 is the terminal arrangement, but the manufacturing method is the same. To be clear, the upper arm circuit and the lower arm circuit are created as shown in FIG. 15(a) and FIG. 15(b), respectively, and the lower arm circuit is flipped over as shown in FIG. 15(c). Then, as shown in FIG. 15(d), they are joined at a joint 330 using a joining member 331.

[0068] (Variation 2) The electric circuit body 400 and the electric circuit body 400A described above may be incorporated into a power conversion device. For ease of explanation, the following will describe an example in which the electric circuit body 400 is incorporated into a power conversion device, representing the electric circuit body 400 and the electric circuit body 400A.

[0069] FIG. 16 is a circuit diagram of a power conversion device 200 including an electric circuit body 400 according to Modification 2. The power conversion device 200 includes a first inverter circuit unit 140, a second inverter circuit unit 142, an auxiliary inverter circuit unit 43, and a capacitor module 500. The first inverter circuit unit 140 and the second inverter circuit unit 142 each include a plurality of semiconductor devices 300, which are connected to form a three-phase bridge circuit. If a larger current capacity is required, additional semiconductor devices 300 can be connected in parallel, corresponding to each phase of the three-phase inverter circuit. The current capacity can also be increased by connecting in parallel the first and second devices 155 and 157, and the first and second diodes 156 and 158, which are power semiconductor elements built into the semiconductor device 300.

[0070] The first inverter circuit unit 140 and the second inverter circuit unit 142 have the same basic circuit configuration, and also have the same control method and operation. The outline of the circuit operation of the first inverter circuit unit 140 and the like is well known, so a detailed description will be omitted here.

[0071] As described above, the upper arm circuit includes first element 155 and first diode 156 as switching power semiconductor elements, and the lower arm circuit includes second element 157 and second diode 158 as switching power semiconductor elements. First element 155 and second element 157 perform switching operations in response to drive signals output from one or the other of two driver circuits that make up driver circuit 174, and convert DC power supplied from battery 136 into three-phase AC power.

[0072] As described above, the first element 155 and the second element 157 have a collector electrode, an emitter electrode, and a gate electrode. The first diode 156 and the second diode 158 have two electrodes: a cathode electrode and an anode electrode. As shown in FIG. 3 , the cathode electrodes of the first diode 156 and the second diode 158 are connected to the collector electrodes of the first element 155 and the second element 157, and the anode electrodes are electrically connected to the emitter electrodes of the first element 155 and the second element 157, respectively. As a result, the current flows in the forward direction from the emitter electrodes of the first element 155 and the second element 157 to the collector electrodes.

[0073] The positive terminal 315B and the negative terminal 319B of the semiconductor device 300 are each connected to a DC terminal for connecting a capacitor of the capacitor module 500. AC power is generated at the connection point between the upper arm circuit and the lower arm circuit. In each semiconductor device 300, the connection point between the upper arm circuit and the lower arm circuit is connected to an AC terminal 320B. The AC terminal 320B of each semiconductor device 300 of each phase is connected to an AC output terminal of the power conversion device 200, and the generated AC power is supplied to the stator winding of the first motor generator 192 or the second motor generator 194.

[0074] The control circuit 172 generates timing signals for controlling the switching timing of the first element 155 and the second element 157 based on input information from a control device or a sensor, such as a current sensor 180, of the device in which the power conversion device 200 is installed. The driver circuit 174 generates drive signals for performing switching operations on the first element 155 and the second element 157 based on the timing signals output from the control circuit 172. Note that reference numerals 181, 182, and 188 denote connectors.

[0075] The semiconductor device 300 in this modification includes a temperature sensor (not shown), and temperature data of the semiconductor device 300 is input to the microcomputer. Voltage information on the DC positive electrode side of the semiconductor device 300 is also input to the microcomputer. The microcomputer detects overtemperature and overvoltage based on this information, and if an overtemperature or overvoltage is detected, stops the switching operation of all first elements 155 and second elements 157, thereby protecting the semiconductor device 300 from overtemperature or overvoltage.

[0076] Fig. 17 is an external perspective view of the power conversion device 200 shown in Fig. 16, and Fig. 18 is a cross-sectional view taken along line XVIII-XVIII of the power conversion device 200 shown in Fig. 17. The power conversion device 200 includes a housing 12 having a substantially rectangular parallelepiped shape. The housing 12 includes an upper case 10, which can also be called a top cover, and a lower case 11 that forms a substantially rectangular parallelepiped when combined with the upper case 10.

[0077] The housing 12 accommodates an electric circuit body 400, a capacitor module 500, and the like. The electric circuit body 400 has a cooling flow path, and a cooling water inlet pipe 13 and a cooling water outlet pipe 14 that communicate with the cooling flow path protrude from one side of the housing 12. As shown in FIG. 17 , the lower case 11 has an opening at the top side, and the upper case 10 is attached to the lower case 11, closing the opening of the lower case 11. The upper case 10 and the lower case 11 are formed of an aluminum alloy or the like and are fixed in place while being sealed from the outside. However, the upper case 10 and the lower case 11 may also be integrally configured. The housing 12 has a simple rectangular parallelepiped shape, which has the advantages of being easy to install in a vehicle or the like and easy to manufacture.

[0078] A connector 17 is attached to one longitudinal side surface of the housing 12, and an AC terminal 18 is connected to this connector 17. In addition, a connector 21 is provided on the surface from which the cooling water inlet pipe 13 and the cooling water outlet pipe 14 are led out.

[0079] As shown in FIG. 18 , an electric circuit body 400 is housed within the housing 12. A control circuit 172 and a driver circuit 174 are disposed above the electric circuit body 400, and a capacitor module 500 is housed on the DC terminal side of the electric circuit body 400. By disposing the capacitor module 500 at the same height as the semiconductor device 300, the power conversion device 200 can be made thinner, improving installation flexibility in a vehicle. An AC side terminal 320B of the electric circuit body 400 is connected to a bus bar 361, passing through the current sensor 180. In addition, a positive side terminal 315B and a negative side terminal 319B, which are DC terminals of the semiconductor device 300, are connected to a positive terminal 362A and a negative terminal 362B of the capacitor module 500, respectively.

[0080] (12) The power conversion device 200 includes a plurality of electric circuit bodies 400 and converts DC power into AC power.

[0081] (Variation 3) Fig. 19 is a diagram showing the shape of a joint 330 in Variation 3. The joint 330 is not limited to the shape shown in the lower part of Fig. 3 in the embodiment. The joint 330 shown in Fig. 19(a) is provided with protrusions 330A on both the first conductor plate 430 and the fourth conductor plate 433, and a joint member 331 is disposed between the two protrusions 330A.

[0082] The joint 330 shown in Fig. 19(b) has protrusions 330A on both the first conductor plate 430 and the fourth conductor plate 433, and further has joint members 331 disposed at two locations between the two protrusions 330A. The joint 330 shown in Fig. 19(c) has a clamping portion made of parallel plates that clamp the fourth conductor plate 433 on the side of the first conductor plate 430. Specifically, the tip portion of the fourth conductor plate 433 is inserted between the parallel plates of the clamping portion provided on the first conductor plate 430. The fourth conductor plate 433 clamped between the parallel plates is electrically connected by the joint members 331.

[0083] (Variation 4) In the above-described embodiment, material bonding such as solder, sintered metal, or conductive adhesive is used for the joint 330. However, mechanical bonding may also be used for the joint 330. For example, fixing with a screw, press fitting, shrink fitting, caulking, etc. may also be used for the joint 330.

[0084] The above-described embodiments and modifications may be combined with each other. Although various embodiments and modifications have been described above, the present invention is not limited to these. Other embodiments conceivable within the scope of the technical concept of the present invention are also included within the scope of the present invention.

[0085] 155: First element 157: Second element 200: Power conversion device 300: Semiconductor device 325L: Lower arm gate terminal 325U: Upper arm gate terminal 330: Joint portion 330A: Protrusion portion 331: Joint member 340: Cooling member 360: Sealing material 381: Upper arm circuit body 382: Lower arm circuit body 400: Electric circuit body 430: First conductor plate 431: Second conductor plate 432: Third conductor plate 433: Fourth conductor plate 440: Upper insulating sheet 441: Lower insulating sheet 453: Heat conduction member

Claims

1. An electric circuit body comprising: a first assembly formed by sandwiching an upper arm semiconductor element in a thickness direction between a first conductor plate and a second conductor plate; a second assembly formed by sandwiching a lower arm semiconductor element in the thickness direction between a third conductor plate and a fourth conductor plate; and a sealing material for sealing the first assembly and the second assembly, wherein the first conductor plate and the fourth conductor plate are mechanically and electrically connected at a joint formed on sides facing each other, the first conductor plate and the fourth conductor plate are arranged on a first substantially identical plane, the second conductor plate and the third conductor plate are arranged on a second substantially identical plane different from the first substantially identical plane, and the upper arm semiconductor element and the lower arm semiconductor element are in a relationship of front-back inversion.

2. The electric circuit body according to claim 1, wherein a first control terminal for controlling the upper arm semiconductor element and a second control terminal for controlling the lower arm semiconductor element are integrally formed with the first conductor plate, the second conductor plate, the third conductor plate, and the fourth conductor plate by the sealing material.

3. The electric circuit body according to claim 1, wherein end faces of the first conductor plate on a side opposite to the upper arm semiconductor element and end faces of the fourth conductor plate on a side opposite to the lower arm semiconductor element coincide in position in the thickness direction, and end faces of the second conductor plate on a side opposite to the upper arm semiconductor element and end faces of the third conductor plate on a side opposite to the lower arm semiconductor element coincide in position in the thickness direction.

4. The electric circuit body according to claim 1, wherein the joint is a mechanical joint or a material joint.

5. The electric circuit body according to claim 1, wherein the joint is a joint using a solder material or a conductive adhesive.

6. The electric circuit body according to claim 1, wherein at least one of the first conductor plate and the fourth conductor plate has a protrusion protruding toward the other on a side facing the other, and the protrusion constitutes the joint.

7. The electric circuit body according to claim 1, further comprising: an upper cooling member in contact with the first conductor plate and the fourth conductor plate via at least a first heat conduction member; and a lower cooling member in contact with the second conductor plate and the third conductor plate via at least a second heat conduction member.

8. The electric circuit body according to claim 7, wherein the thermal conductivities of the first thermal conduction member and the second thermal conduction member are 5 to 10 W / (m·K).

9. The electric circuit body according to claim 1, further comprising an upper cooling member in contact with the first conductor plate and the fourth conductor plate via a first thermal conduction member and a first insulating sheet, and a lower cooling member in contact with the second conductor plate and the third conductor plate via a second thermal conduction member and a second insulating sheet.

10. A power conversion device comprising one or more electric circuit bodies according to claim 1, for converting DC power into AC power.

11. A method for manufacturing an electric circuit body, comprising: a first forming step of forming a first assembly by sandwiching an upper arm semiconductor element in the thickness direction between a first conductor plate and a second conductor plate; a second forming step of forming a second assembly by sandwiching a lower arm semiconductor element in the thickness direction between a third conductor plate and a fourth conductor plate; an assembly arranging step of arranging the first assembly and the second assembly such that after the first forming step and the second forming step, the first conductor plate and the fourth conductor plate are on a first substantially identical plane, the second conductor plate and the third conductor plate are on a second substantially identical plane different from the first substantially identical plane, and the upper arm semiconductor element and the lower arm semiconductor element are in a state of being reversed front and back; and a joining step of mechanically and electrically joining the first conductor plate and the fourth conductor plate.

12. The method for manufacturing an electric circuit body according to claim 11, further comprising: a sheet arranging step of arranging an upper insulating sheet and a lower insulating sheet so as to sandwich the first substantially identical plane and the second substantially identical plane; and a sealing material forming step of arranging a mold so as to cover the upper insulating sheet and the lower insulating sheet, and injecting a sealing material into the inside of the mold while pressing the upper insulating sheet and the lower insulating sheet using the mold.

13. The method for manufacturing an electric circuit body according to claim 12, wherein in the assembly arranging step, a soldering material or a conductive adhesive is disposed between the first conductor plate and the fourth conductor plate, and the sealing material forming step also serves as the joining step.

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