power module

Abstract

A power module capable of further reducing inductance is provided. The power module includes a lower arm portion (10) having a first negative electrode side semiconductor element (11) and a second negative electrode side semiconductor element (12), a first upper arm portion (20) having a first positive electrode side semiconductor element (21) and being arranged side by side with the lower arm portion (10) on one side of the lower arm portion (10), and a second upper arm portion (30) having a second positive electrode side semiconductor element (31) and being arranged side by side with the lower arm portion (10) on the other side of the lower arm portion (10), one side surface of the lower arm portion (10) opposing a side surface of the first upper arm portion (20), and the other side surface of the lower arm portion (10) opposing a side surface of the second upper arm portion (30).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a power module. BACKGROUND

[0002] An electric vehicle such as a hybrid vehicle, or an electric vehicle is equipped with a power conversion device such as a DC / AC inverter, a DC / DC converter. A power module is used as one of components of the power conversion device.

[0003] In Patent Literature 1, a power module is described. The power module includes a multilayer substrate, a first semiconductor element electrically connected to a conductor layer of the multilayer substrate, and a second semiconductor element electrically connected to another conductor layer of the multilayer substrate. Further, the power module has a first input terminal electrically connected to an electrode of the first semiconductor element, and a second input terminal electrically connected to an electrode of the second semiconductor element. The first input terminal and the second input terminal constitute a parallel flat plate. Thereby, it is possible to reduce the inductance of the power module.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent No. 6203232 SUMMARY

[0007] PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] However, in the power module of Patent Literature 1, the inductance reduction effect is obtained only between the first input terminal and the second input terminal. Therefore, in the structure of Patent Literature 1, there is a problem that the inductance of the power module cannot be sufficiently reduced.

[0009] The present disclosure is to solve the above problem, and aims to provide a power module capable of further reducing the inductance.

[0010] MEANS OF SOLVING THE PROBLEMS

[0011] The power module according to the present disclosure includes a lower arm portion having a first negative electrode side semiconductor element and a second negative electrode side semiconductor element, a first upper arm portion having a first positive electrode side semiconductor element and being arranged side by side with the lower arm portion on one side of the lower arm portion, and a second upper arm portion having a second positive electrode side semiconductor element and being arranged side by side with the lower arm portion on the other side of the lower arm portion, a negative electrode side input terminal being formed at one end of the lower arm portion, a first positive electrode side input terminal being formed at one end of the first upper arm portion and being arranged side by side with the negative electrode side input terminal, a second positive electrode side input terminal being formed at one end of the second upper arm portion and being arranged side by side with the negative electrode side input terminal, the other end of the lower arm portion, the other end of the first upper arm portion, and the other end of the second upper arm portion being electrically connected to an output terminal, one side surface of the lower arm portion being opposite to a side surface of the first upper arm portion, and the other side surface of the lower arm portion being opposite to a side surface of the second upper arm portion.

[0012] Inventive Effects

[0013] According to the present disclosure, the inductance of the power module can be further reduced. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a plan view showing the physical structure of the power module of Embodiment 1.

[0015] Figure 2 is an equivalent circuit diagram showing the circuit structure of the power module of Embodiment 1.

[0016] Figure 3 is a schematic cross-sectional view showing the positional relationship between the conductor constituting the upper arm and the conductor constituting the lower arm in the power module of the comparative example of Embodiment 1.

[0017] Figure 4 is a schematic cross-sectional view showing the positional relationship between the conductor constituting the upper arm and the conductor constituting the lower arm in the power module of the comparative example of Embodiment 1.

[0018] Figure 5 is a schematic cross-sectional view showing the positional relationship between the conductor constituting the upper arm and the conductor constituting the lower arm in the power module of Embodiment 1.

[0019] Figure 6 is a schematic cross-sectional view showing the positional relationship between the conductor constituting the upper arm and the conductor constituting the lower arm in the power module of Embodiment 1.

[0020] Figure 7 is a diagram showing the flow of current immediately after the positive electrode side semiconductor element is turned off in a general power module.

[0021] Figure 8is a view showing the flow of current immediately after the positive electrode side semiconductor element is turned off in the power module of Embodiment 1.

[0022] Figure 9 is a view showing the flow of current immediately after the positive electrode side semiconductor element is turned on in the power module of Embodiment 1.

[0023] Figure 10 is a view showing the flow of current immediately after the positive electrode side semiconductor element is turned on in the power module of Embodiment 1.

[0024] Figure 11 is a plan view showing the physical structure of the power module of Embodiment 2.

[0025] Figure 12 is a perspective view showing a part of the structure of the power module of Embodiment 3. DETAILED DESCRIPTION

[0026] Embodiment 1.

[0027] A power module related to Embodiment 1 will be described. Figure 1 is a plan view showing the physical structure of the power module of the present embodiment. The power module of the present embodiment constitutes a single-phase inverter circuit. The power module of the present embodiment is used, for example, as one of the components of a power conversion device for a vehicle.

[0028] As shown in Figure 1 , the power module has a lower arm portion 10, a first upper arm portion 20, a second upper arm portion 30, and an alternating-current side arm portion 50. In Figure 1 , the power module is configured to be linearly symmetrical with the center line 10a as the axis of symmetry. The center line 10a passes through the center of the lower arm portion 10 in the width direction of the lower arm portion 10. The first upper arm portion 20 and the second upper arm portion 30 are provided on both sides sandwiching the lower arm portion 10.

[0029] The lower arm portion 10 constitutes two lower arms in the single-phase inverter circuit. The lower arm portion 10 extends along the center line 10a. The lower arm portion 10 has a first conductor pattern 13 and a second conductor pattern 14 separated from the first conductor pattern 13. Both the first conductor pattern 13 and the second conductor pattern 14 are formed on the substrate surface of an insulating substrate 60.

[0030] A negative electrode side input terminal 15 is formed at one end of the lower arm portion 10. The negative electrode side input terminal 15 is formed in the second conductor pattern 14. That is, the second conductor pattern 14 is provided at the one end side of the lower arm portion 10.

[0031] The first conductor pattern 13 is provided at the other end side of the lower arm portion 10.

[0032] The lower arm portion 10 has the first negative electrode side semiconductor element 11 and the second negative electrode side semiconductor element 12 arranged side by side with each other. The lower arm portion 10 can have two or more first negative electrode side semiconductor elements 11. The lower arm portion 10 can have two or more second negative electrode side semiconductor elements 12.

[0033] The first negative electrode side semiconductor element 11 is a switching element that operates based on a voltage signal input via a signal terminal 11a. A source terminal is formed on a surface side of the first negative electrode side semiconductor element 11. A drain terminal is formed on a back surface side of the first negative electrode side semiconductor element 11.

[0034] The second negative electrode side semiconductor element 12 is a switching element that operates based on a voltage signal input via a signal terminal 12a. A source terminal is formed on a surface side of the second negative electrode side semiconductor element 12. A drain terminal is formed on a back surface side of the second negative electrode side semiconductor element 12.

[0035] The first negative electrode side semiconductor element 11 and the second negative electrode side semiconductor element 12 are both provided in the first conductor pattern 13. The first negative electrode side semiconductor element 11 and the second negative electrode side semiconductor element 12 are respectively mounted on a surface of the first conductor pattern 13 by direct bonding. Thereby, the respective drain terminals of the first negative electrode side semiconductor element 11 and the second negative electrode side semiconductor element 12 are electrically connected to the first conductor pattern 13.

[0036] The first lead frame 16 is provided between the surface of the first negative electrode side semiconductor element 11 and the second conductor pattern 14. The source terminal of the first negative electrode side semiconductor element 11 is electrically connected to the second conductor pattern 14 via the first lead frame 16.

[0037] The first lead frame 16 is formed in a plate shape. The first lead frame 16 has a planar shape of a long rectangular shape that is long in one direction. One end portion 16a of the first lead frame 16 in the long direction is engaged with the surface of the first negative electrode side semiconductor element 11 by direct bonding. The other end portion 16b of the first lead frame 16 in the long direction is engaged with the second conductor pattern 14. The long direction of the first lead frame 16 is parallel to the extension direction of the lower arm portion 10, that is, parallel to the up-down direction in the lower arm portion 10. Figure 1

[0038] The second lead frame 17 is provided between the surface of the second negative electrode side semiconductor element 12 and the second conductor pattern 14. The source terminal of the second negative electrode side semiconductor element 12 is electrically connected to the second conductor pattern 14 via the second lead frame 17.

[0039] ​The second lead frame 17 is formed in a plate shape. The second lead frame 17 has a planar shape of a long rectangular shape that is long in one direction. One end portion 17a of the second lead frame 17 in the long direction is joined with the surface of the second negative-side semiconductor element 12 by direct bonding. The other end portion 17b of the second lead frame 17 in the long direction is joined with the second conductor pattern 14. The long direction of the second lead frame 17 is parallel to the extension direction of the lower arm portion 10, that is, parallel to the up-down direction in Figure 1

[0040] The first upper arm portion 20 constitutes one of two upper arms in the single-phase inverter circuit. The first upper arm portion 20 extends side by side with the lower arm portion 10. The first upper arm portion 20 is provided on one side of the lower arm portion 10. In Figure 1

[0041] The first upper arm portion 20 has a third conductor pattern 23. The third conductor pattern 23 is formed on the substrate face of the insulating substrate 60, that is, on the same plane as the first conductor pattern 13 and the second conductor pattern 14 of the lower arm portion 10. The third conductor pattern 23 is separate from any of the first conductor pattern 13 and the second conductor pattern 14.

[0042] The side face 23a of the third conductor pattern 23 of the first upper arm portion 20 opposes one side face 14a of the second conductor pattern 14 of the lower arm portion 10 with the gap 27 interposed therebetween. The side face 23a and the side face 14a are formed parallel to each other. Thus, the third conductor pattern 23 of the first upper arm portion 20 and the second conductor pattern 14 of the lower arm portion 10 constitute parallel planes that oppose each other in the direction along the substrate face of the insulating substrate 60.

[0043] Current flows along the side face 23a through the third conductor pattern 23. Current flows along the side face 14a through the second conductor pattern 14. When current flows through the third conductor pattern 23 at the time of ordinary operation of the power module, current in a direction parallel to the direction of the current flowing through the third conductor pattern 23 flows through the second conductor pattern 14. In order to obtain the effect of the parallel planes described later, the distance between the side face 23a and the side face 14a is preferably 5 mm or less.

[0044] The first positive-side input terminal 25 is formed at one end of the first upper arm portion 20. The first positive-side input terminal 25 is arranged side by side with the negative-side input terminal 15. The first positive-side input terminal 25 is formed in the third conductor pattern 23.

[0045] ​​The first upper arm section 20 has a first positive-side semiconductor element 21. The first upper arm section 20 can have two or more first positive-side semiconductor elements 21. The first positive-side semiconductor element 21 is a switching element that operates based on a voltage signal input via a signal terminal 21a. A source terminal is formed on a surface side of the first positive-side semiconductor element 21. A drain terminal is formed on a back surface side of the first positive-side semiconductor element 21.

[0046] The first positive-side semiconductor element 21 is provided in the third conductor pattern 23. The first positive-side semiconductor element 21 is mounted on a surface of the third conductor pattern 23 by direct bonding. Thereby, the drain terminal of the first positive-side semiconductor element 21 is electrically connected to the third conductor pattern 23.

[0047] The third lead frame 26 is provided between the surface of the first positive-side semiconductor element 21 and the first conductor pattern 13 of the lower arm section 10. The source terminal of the first positive-side semiconductor element 21 is electrically connected to the first conductor pattern 13 via the third lead frame 26.

[0048] The third lead frame 26 is formed in a plate shape. The third lead frame 26 has a planar shape of a long rectangular shape that is long in one direction. One end portion 26a of the third lead frame 26 in the long direction is joined to the surface of the first positive-side semiconductor element 21 by direct bonding. The other end portion 26b of the third lead frame 26 in the long direction is joined to the first conductor pattern 13. The end portion 26b of the third lead frame 26 is the other end of the first upper arm section 20. The long direction of the third lead frame 26 is parallel to each of the long directions of the first lead frame 16 and the second lead frame 17.

[0049] At least a part of a side surface 26c of the third lead frame 26 opposes a side surface 16c of the first lead frame 16. The side surface 26c and the side surface 16c are formed parallel to each other. Thereby, the third lead frame 26 of the first upper arm section 20 and the first lead frame 16 of the lower arm section 10 constitute parallel flat plates that oppose each other in a direction along the surface of the insulating substrate 60.

[0050] The second upper arm section 30 constitutes the other of the two upper arms in the single-phase inverter circuit. The second upper arm section 30 extends side by side with the lower arm section 10. The second upper arm section 30 is provided on the other side of the lower arm section 10. In Figure 1 In the embodiment, the second upper arm section 30 is disposed on the right side of the lower arm section 10. The second upper arm section 30 is configured to be line-symmetrical to the first upper arm section 20 with the center line 10a as the axis of symmetry.

[0051] The second upper arm section 30 has a fourth conductor pattern 33. The fourth conductor pattern 33 is formed on the substrate face of the insulating substrate 60, that is, on the same plane as the first conductor pattern 13 and the second conductor pattern 14 of the lower arm section 10. The fourth conductor pattern 33 is separated from any one of the first conductor pattern 13 and the second conductor pattern 14.

[0052] The side face 33a of the fourth conductor pattern 33 of the second upper arm section 30 opposes the other side face 14b of the second conductor pattern 14 of the lower arm section 10 with the gap 37 interposed therebetween. The side face 33a and the side face 14b are formed in parallel to each other. Thus, the fourth conductor pattern 33 of the second upper arm section 30 and the second conductor pattern 14 of the lower arm section 10 constitute parallel plates opposing each other in the direction along the substrate face of the insulating substrate 60.

[0053] Current flows along the side face 33a through the fourth conductor pattern 33. Current flows along the side face 14b through the second conductor pattern 14. At the time of normal operation of the power module, when current flows through the fourth conductor pattern 33, current in a direction parallel to the direction of the current flowing through the fourth conductor pattern 33 flows through the second conductor pattern 14. In order to obtain the effect of the parallel plates described later, the distance between the side face 33a and the side face 14b is preferably 5 mm or less.

[0054] The second positive-side input terminal 35 is formed at one end of the second upper arm section 30. The second positive-side input terminal 35 is arranged side by side with the negative-side input terminal 15. The second positive-side input terminal 35 is formed in the fourth conductor pattern 33.

[0055] The second upper arm section 30 has the second positive-side semiconductor element 31. The second upper arm section 30 can have two or more second positive-side semiconductor elements 31. The second positive-side semiconductor element 31 is a switching element that operates based on a voltage signal input via the signal terminal 31a. The source terminal is formed on the surface side of the second positive-side semiconductor element 31. The drain terminal is formed on the back face side of the second positive-side semiconductor element 31.

[0056] The second positive-side semiconductor element 31 is provided in the fourth conductor pattern 33. The second positive-side semiconductor element 31 is mounted on the surface of the fourth conductor pattern 33 by direct bonding. Thus, the drain terminal of the second positive-side semiconductor element 31 is electrically connected to the fourth conductor pattern 33.

[0057] The fourth lead frame 36 is provided between the surface of the second positive-side semiconductor element 31 and the first conductor pattern 13 of the lower arm section 10. The source terminal of the second positive-side semiconductor element 31 is electrically connected to the first conductor pattern 13 via the fourth lead frame 36.

[0058] The fourth lead frame 36 is formed in a plate shape. The fourth lead frame 36 has a planar shape of a long rectangular shape that is long in one direction. One end portion 36a of the fourth lead frame 36 in the long direction is joined to the surface of the second positive-side semiconductor element 31 by direct bonding. The other end portion 36b of the fourth lead frame 36 in the long direction is joined to the first conductor pattern 13. The end portion 36b of the fourth lead frame 36 is the other end of the second upper arm portion 30. The long direction of the fourth lead frame 36 is parallel to the respective long directions of the first lead frame 16, the second lead frame 17, and the third lead frame 26.

[0059] At least a portion of the side surface 36c of the fourth lead frame 36 opposes the side surface 17c of the second lead frame 17. The side surface 36c and the side surface 17c are formed parallel to each other. Thus, the fourth lead frame 36 of the second upper arm portion 30 and the second lead frame 17 of the lower arm portion 10 constitute parallel plates that oppose each other in the direction of the substrate face of the insulating substrate 60.

[0060] The AC-side arm portion 50 constitutes an AC-side arm in the single-phase inverter circuit. The AC-side arm portion 50 has an AC-side output terminal 51. The output terminal 51 is disposed on the center line 10a. The output terminal 51 is formed on the substrate face of the insulating substrate 60.

[0061] The output terminal 51 is electrically connected to the first conductor pattern 13 that is the other end of the lower arm portion 10, the end portion 26b of the third lead frame 26 that is the other end of the first upper arm portion 20, and the end portion 36b of the fourth lead frame 36 that is the other end of the second upper arm portion 30, respectively. In the present embodiment, the output terminal 51 is formed integrally with the first conductor pattern 13.

[0062] Figure 2 is an equivalent circuit diagram that represents the circuit structure of the power module of the present embodiment. In Figure 2 the equivalent circuit diagram, the positional relationship of the respective semiconductor elements and the respective current paths corresponds to the physical positional relationship of the respective semiconductor elements and the respective current paths shown in Figure 1 .

[0063] As shown in Figure 2 , the drain terminal D of the first positive-side semiconductor element 21 is connected to a first positive-side input terminal 25. The first positive-side input terminal 25 is connected to the positive electrode of a direct-current power supply that is not shown. The current path between the first positive-side semiconductor element 21 and the first positive-side input terminal 25 corresponds to the third conductor pattern 23 shown in Figure 1 .

[0064] The source terminal S of the first positive-side semiconductor element 21 is connected to the output terminal 51 and to the drain terminal D of the first negative-side semiconductor element 11. The current path between the first positive-side semiconductor element 21 and the output terminal 51 corresponds to Figure 1 the third lead frame 26 and the first conductor pattern 13 illustrated. The current path between the first positive-side semiconductor element 21 and the first negative-side semiconductor element 11 also corresponds to the third lead frame 26 and the first conductor pattern 13.

[0065] The source terminal S of the first negative-side semiconductor element 11 is connected to the negative-side input terminal 15. The negative-side input terminal 15 is connected to the negative electrode of a direct-current power supply, which is not illustrated. The current path between the first negative-side semiconductor element 11 and the negative-side input terminal 15 corresponds to Figure 1 the first lead frame 16 and the second conductor pattern 14 illustrated.

[0066] The drain terminal D of the second positive-side semiconductor element 31 is connected to the second positive-side input terminal 35. The second positive-side input terminal 35 is connected to the positive electrode of a direct-current power supply, which is not illustrated. The current path between the second positive-side semiconductor element 31 and the second positive-side input terminal 35 corresponds to Figure 1 the fourth conductor pattern 33 illustrated.

[0067] The source terminal S of the second positive-side semiconductor element 31 is connected to the output terminal 51 and to the drain terminal D of the second negative-side semiconductor element 12. The current path between the second positive-side semiconductor element 31 and the output terminal 51 corresponds to Figure 1 the fourth lead frame 36 and the first conductor pattern 13 illustrated. The current path between the second positive-side semiconductor element 31 and the second negative-side semiconductor element 12 also corresponds to the fourth lead frame 36 and the first conductor pattern 13.

[0068] The source terminal S of the second negative-side semiconductor element 12 is connected to the negative-side input terminal 15. The current path between the second negative-side semiconductor element 12 and the negative-side input terminal 15 corresponds to Figure 1 the second lead frame 17 and the second conductor pattern 14 illustrated.

[0069] Next, the principle of the inductance reduction effect obtained by the structure of the power module of the present embodiment will be described. First, the positional relationship of the conductors in the power module of the comparative example of the present embodiment will be described.

[0070] Figure 3 and Figure 4 are schematic sectional views showing the positional relationship of the conductors constituting the upper arm and the conductors constituting the lower arm in the power module of the comparative example of the present embodiment. As Figure 3As shown, the conductor 101 and the conductor 102 each have a rectangular cross-sectional shape. The conductor 101 is a conductor that constitutes an upper arm. The conductor 102 is a conductor that constitutes a lower arm.

[0071] The conductor 101 and the conductor 102 are arranged on the same plane. The conductor 101 and the conductor 102 are arranged side by side with the gap 103 interposed therebetween. In the conductor 101 and the conductor 102, currents flow in mutually parallel directions in opposite directions.

[0072] In Figure 4 , for the sake of simplifying the calculation, the conductor 101 and the conductor 102 are replaced by a cylindrical wire 104 and a cylindrical wire 105, respectively. The cylindrical wire 104 is a wire equivalent to the conductor 101. The impedance of the cylindrical wire 104 is equal to the impedance of the conductor 101. The center of the cylindrical wire 104 is at the center of gravity of the current density distribution at the cross section of the conductor 101 as shown. Figure 3 The radius of the cylindrical wire 104 is R1.

[0073] The cylindrical wire 105 is a wire equivalent to the conductor 102. The impedance of the cylindrical wire 105 is equal to the impedance of the conductor 102. The center of the cylindrical wire 105 is at the center of gravity of the current density distribution at the cross section of the conductor 102 as shown. Figure 3 The radius of the cylindrical wire 105 is R2. The distance between the cylindrical wire 104 and the cylindrical wire 105 is d.

[0074] The current path of the upper arm, i.e., the current path from the positive-side input terminal to the output terminal, is set to S1. The current path of the lower arm, i.e., the current path from the output terminal to the negative-side input terminal, is set to S2. When a current flows from the positive-side input terminal to the negative-side input terminal via the output terminal, the self-inductance L of the power module is expressed in accordance with the Neumann formula as shown in the following equation (1).

[0075] [Mathematical expression 1]

[0076]

[0077] Here, μ is the magnetic permeability of the wire. r(l1, l2) is the distance between a position at a distance l1 from the start point in the path S1 and a position at a distance l2 from the start point in the path S2. If the center distance between the path S1 and the path S2 is set to a fixed value r and the distance l1 and the distance l2 are each set to l, the self-inductance L(r) when only a direct current passes through the path S1 and the path S2 is shown in the following equation (2).

[0078] [Mathematical expression 2]

[0079]

[0080] Further, when an alternating current having a very high frequency flows through the path S1 and the path S2, the current flows only on the surface of each conductor, and the self-inductance L'(r) is given by the following equation (3).

[0081] [Math. 3]

[0082]

[0083] Here, let R1 = 10 [mm], R2 = 20 [mm], and l = 25 [mm]. In this case, the value ΔL' obtained by subtracting the resultant inductance of the path S1 and the path S2 at a distance d of 1 mm from the resultant inductance of the path S1 and the path S2 at a distance d of 5 mm is given by the following equation (4), and is about 4.4 nH.

[0084] [Math. 4]

[0085]

[0086] Generally, the wiring inductance in a power module is mostly 20 nH or less. In a power module, if the distance between two plate-shaped conductors arranged on the same plane exceeds 5 mm, the inductance reduction effect cannot be effectively obtained between the conductors. That is, between two plate-shaped conductors arranged on the same plane, in order to effectively obtain the inductance reduction effect, the distance between the two plate-shaped conductors is preferably 5 mm or less. On this basis, if the distance between two plate-shaped conductors arranged on the same plane exceeds 5 mm, the power module is upsized on the plane, and thus the output density of the inverter, that is, the output per unit volume of the inverter decreases. That is, in order to suppress the decrease in the output density of the inverter, the distance between the two plate-shaped conductors is also preferably 5 mm or less. On the other hand, if the distance between two plate-shaped conductors arranged on the same plane is shortened, the insulation between the two plate-shaped conductors decreases. In order to ensure the insulation between the two plate-shaped conductors, the distance between the two plate-shaped conductors is preferably greater than 0 mm. If the distance between the two plate-shaped conductors is greater than 0 mm and 5 mm or less, in an actual product, a balance can be achieved between the reduction in inductance and the suppression of the decrease in the output density and the insulation.

[0087] Next, the positional relationship of the conductors in the power module of the present embodiment will be described. Figure 5 and Figure 6 is a schematic cross-sectional view showing the positional relationship of the conductors constituting the upper arm and the conductors constituting the lower arm in the power module of the present embodiment.

[0088] The power module of this embodiment has a circuit in which current flows from the first positive-side input terminal 25 to the negative-side input terminal 15 via the output terminal 51, and a circuit in which current flows from the second positive-side input terminal 35 to the negative-side input terminal 15 via the output terminal 51. The power module of this embodiment can be considered to have a parallel circuit obtained by connecting these two circuits in parallel.

[0089] Here, the current path from the first positive-side input terminal 25 to the output terminal 51 is set as path S1, the current path from the second positive-side input terminal 35 to the output terminal 51 is set as path S1', and the current path from the output terminal 51 to the negative-side input terminal 15 is set as path S2. Since the power module of this embodiment is configured to be line-symmetrical with the center line 10a as the axis of symmetry, it can be considered that path S1 = path S1'.

[0090] As shown in FIG. 6, the conductor 106, the conductor 107, the conductor 108, and the conductor 109 each have an oblong cross-sectional shape. The conductor 106 is a conductor that constitutes one upper arm. The conductor 106 corresponds to, for example, the third conductor pattern 23 of the first upper arm portion 20 shown in FIG. 2. Figure 5 The conductor 107 and the conductor 108 are conductors that constitute two lower arms. The conductor 107 and the conductor 108 correspond to, for example, the second conductor pattern 14 of the lower arm portion 10 shown in FIG. 1. The conductor 109 is a conductor that constitutes another upper arm. The conductor 109 corresponds to, for example, the fourth conductor pattern 33 of the second upper arm portion 30 shown in FIG. 4. Figure 1 The conductor 107 and the conductor 108 are conductors that constitute two lower arms. The conductor 107 and the conductor 108 correspond to, for example, the second conductor pattern 14 of the lower arm portion 10 shown in FIG. 1. The conductor 109 is a conductor that constitutes another upper arm. The conductor 109 corresponds to, for example, the fourth conductor pattern 33 of the second upper arm portion 30 shown in FIG. 4. Figure 1 The conductor 107 and the conductor 108 are conductors that constitute two lower arms. The conductor 107 and the conductor 108 correspond to, for example, the second conductor pattern 14 of the lower arm portion 10 shown in FIG. 1. The conductor 109 is a conductor that constitutes another upper arm. The conductor 109 corresponds to, for example, the fourth conductor pattern 33 of the second upper arm portion 30 shown in FIG. 4. Figure 1 The conductor 107 and the conductor 108 are conductors that constitute two lower arms. The conductor 107 and the conductor 108 correspond to, for example, the second conductor pattern 14 of the lower arm portion 10 shown in FIG. 1. The conductor 109 is a conductor that constitutes another upper arm. The conductor 109 corresponds to, for example, the fourth conductor pattern 33 of the second upper arm portion 30 shown in FIG. 4.

[0091] The conductor 106, the conductor 107, the conductor 108, and the conductor 109 are arranged on the same plane. The conductor 106 and the conductor 107 are arranged side by side with the gap 110 interposed therebetween. In the conductor 106 and the conductor 107, currents flow in opposite directions in parallel with each other. The conductor 107 and the conductor 108 are in contact with each other. In the conductor 107 and the conductor 108, currents flow in the same direction. The conductor 108 and the conductor 109 are arranged side by side with the gap 111 interposed therebetween. In the conductor 108 and the conductor 109, currents flow in opposite directions in parallel with each other.

[0092] In FIG. 6, for the sake of simplifying the calculation, the conductor 106, the conductor 107, the conductor 108, and the conductor 109 are replaced by a cylindrical wire 112, a cylindrical wire 113, a cylindrical wire 114, and a cylindrical wire 115, respectively. Figure 6 The cylindrical wire 112 is a wire equivalent to the conductor 106. The impedance of the cylindrical wire 112 is equal to the impedance of the conductor 106. The center of the cylindrical wire 112 is on the center line 10a.

[0093] The cylindrical wire 113 is a wire equivalent to the conductor 107. The impedance of the cylindrical wire 113 is equal to the impedance of the conductor 107. The center of the cylindrical wire 113 is on the center line 10a. Figure 5The centroid of the current density distribution at the cross-section of conductor 106 is shown. The radius of the cylindrical wire 112 is R1.

[0094] Cylindrical conductor 113 is an equivalent conductor to conductor 107. The impedance of cylindrical conductor 113 is equal to the impedance of conductor 107. The center of cylindrical conductor 113 is located at... Figure 5 The centroid of the current density distribution at the cross-section of conductor 107 is shown. The radius of the cylindrical conductor 113 is R2.

[0095] Cylindrical conductor 114 is an equivalent conductor to conductor 108. The impedance of cylindrical conductor 114 is equal to the impedance of conductor 108. The center of cylindrical conductor 114 is located at... Figure 5 The centroid of the current density distribution at the cross-section of conductor 108 is shown. The radius of the cylindrical wire 114 is R2.

[0096] Cylindrical conductor 115 is equivalent to conductor 109. The impedance of cylindrical conductor 115 is equal to the impedance of conductor 109. The center of cylindrical conductor 115 is located at... Figure 5 The centroid of the current density distribution at the cross-section of conductor 109 is shown. The radius of the cylindrical wire 115 is R1.

[0097] In this embodiment, since the two circuits are connected in parallel, the inner conductors 106 and 107 are replaced with two cylindrical wires 113 and 114. Therefore, the center of cylindrical wire 113 is close to the outer cylindrical wire 112, and the center of cylindrical wire 114 is close to the outer cylindrical wire 115. Thus, if compared with… Figure 4 Compared to the structure shown, the distances between the centers of cylindrical conductor 113 and 112, and between the centers of cylindrical conductor 114 and 115, can be shortened. Since the strength of the magnetic field influence is inversely proportional to the distance, this embodiment enhances the interaction of the magnetic fields between cylindrical conductors 113 and 112, and between cylindrical conductors 114 and 115. Furthermore, if the frequency of the alternating current increases, the skin effect becomes stronger, resulting in a higher current density on the conductor surface and a lower current density inside the conductor. Therefore, if the frequency of the alternating current increases, the actual distances between cylindrical conductors 113 and 112, and between cylindrical conductors 114 and 115, are shorter than the distances between their centers, thus further strengthening the interaction of the magnetic fields.

[0098] Figure 7 This is a diagram showing the current flow in a typical power module immediately after the positive-side semiconductor element is turned off. Figure 7In the present embodiment, only a set of the upper arm having the positive electrode side semiconductor element 120 and the lower arm having the negative electrode side semiconductor element 121 is shown.

[0099] As Figure 7 shown, when the positive electrode side semiconductor element 120 changes from on to off, the on current 122 flowing through the positive electrode side semiconductor element 120 decreases. In the entire circuit, the inductance works in the direction in which the current is to be maintained, and thus a backflow current 123 toward the AC side is generated. The backflow current 123 is a current generated by the inductance of the AC side bus bar provided outside the power module. Therefore, the electromotive force generated by the inductance of the positive electrode side and negative electrode side bus bars provided outside the power module and the inductance of the conductor inside the power module are directly applied to the positive electrode side semiconductor element 120, respectively. Thereby, a potential difference is generated between the source terminal and the drain terminal of the positive electrode side semiconductor element 120, and a surge voltage is generated. Therefore, the switching loss in the power module increases.

[0100] Figure 8 is a view showing the flow of the current immediately after the positive electrode side semiconductor element is turned off in the power module of the present embodiment. The backflow current 81 is a current generated by the inductance of the current to be maintained in the AC side bus bar. Therefore, as the on current 80 decreases, the backflow current 81 increases. Thereby, a magnetic field that hinders the increase of the backflow current 81 and is caused by the backflow current 81 itself is generated in the lower arm portion 10 through which the backflow current 81 flows. That is, the eddy current generated by the inductance of the lower arm portion 10 hinders the increase of the backflow current 81. As a result, a corresponding potential difference is applied to the positive electrode side semiconductor element that is turned off, and a surge voltage is generated.

[0101] However, in the present embodiment, the first upper arm portion 20 and the second upper arm portion 30 each constitute a parallel plate with the lower arm portion 10. Therefore, when the on current 80 flowing through one of the first upper arm portion 20 and the second upper arm portion 30 decreases, a magnetic field that causes the backflow current 81 flowing in the same direction as the on current 80 flowing through the other of the first upper arm portion 20 and the second upper arm portion 30 to increase is generated in the other upper arm portion. The closer the distance to the upper arm portion that is the source of the magnetic field, the greater the influence of the magnetic field.

[0102] The above-described magnetic field generated in the upper arm portion when the positive electrode side semiconductor element is turned off cancels out the magnetic field generated in the lower arm portion 10 when the backflow current 81 increases. Thereby, the surge voltage applied to the positive electrode side semiconductor element decreases, and the apparent inductance decreases.

[0103] Figure 9 is a view showing the flow of the current immediately after the positive electrode side semiconductor element is turned on in a general power module. As Figure 9As shown, when the positive-side semiconductor element 120 changes from off to on, an on current 124 flowing through the positive-side semiconductor element 120 is generated, and the on current 124 increases with time. In the entire circuit, since the inductance works in the direction in which the current is to be maintained, a recovery current 125 is generated by the electric charge stored in the negative-side semiconductor element 121.

[0104] As with the return current 123, the recovery current 125 is a current generated by the inductance of the AC-side bus bar provided outside the power module. Therefore, the electromotive force generated by the inductance possessed by the positive-side and negative-side bus bars provided outside the power module and the inductance possessed by the conductors inside the power module are directly applied to the positive-side semiconductor element 120, respectively. Thereby, a potential difference is generated between the source terminal and the drain terminal of the positive-side semiconductor element 120, and a surge voltage is generated. Therefore, the switching loss in the power module increases.

[0105] Figure 10 is a view showing the flow of the current immediately after the positive-side semiconductor element turns on in the power module of the present embodiment. The recovery current 83 is a current generated by the inductance to maintain the current of the AC-side bus bar. Therefore, as the on current 82 increases, the recovery current 83 also increases. Thereby, in the lower arm portion 10 through which the recovery current 83 flows, a magnetic field that prevents the increase of the recovery current 83 and is caused by the recovery current 83 itself is generated. That is, the eddy current generated by the inductance of the lower arm portion 10 hinders the increase of the recovery current 83. As a result, a corresponding potential difference is applied to the positive-side semiconductor element that has turned on, and a surge voltage is generated.

[0106] However, in the present embodiment, the first upper arm portion 20 and the second upper arm portion 30 each constitute a parallel plate with the lower arm portion 10. Therefore, when the on current 82 flowing through one of the first upper arm portion 20 and the second upper arm portion 30 increases, a magnetic field is generated in the other of the first upper arm portion 20 and the second upper arm portion 30, which increases the recovery current 83 flowing in the direction opposite to the direction of the on current 82 flowing through the other upper arm portion. The closer the distance to the upper arm portion that is the source of the magnetic field, the greater the influence of the magnetic field.

[0107] The above-described magnetic field generated in the upper arm portion when the positive-side semiconductor element turns on cancels out the magnetic field generated in the lower arm portion 10 when the recovery current 83 increases. Thereby, the surge voltage applied to the positive-side semiconductor element decreases, and the apparent inductance decreases.

[0108] If the distance between the upper arm portion and the lower arm portion is far, the magnetic field interaction between the upper arm portion and the lower arm portion is weakened. In the present embodiment, since the lower arm portion 10 is sandwiched by the first upper arm portion 20 and the second upper arm portion 30, the distance between each of the first upper arm portion 20 and the second upper arm portion 30 and the lower arm portion 10 can be made close. Therefore, according to the present embodiment, the magnetic field interaction between each of the first upper arm portion 20 and the second upper arm portion 30 and the lower arm portion 10 can be further enhanced, and thus the inductance of the power module can be further reduced.

[0109] As described above, the power module of the present embodiment includes the lower arm portion 10, the first upper arm portion 20, and the second upper arm portion 30. The lower arm portion 10 has the first negative-side semiconductor element 11 and the second negative-side semiconductor element 12. The first upper arm portion 20 has the first positive-side semiconductor element 21. The first upper arm portion 20 is arranged side by side with the lower arm portion 10 on one side of the lower arm portion 10. The second upper arm portion 30 has the second positive-side semiconductor element 31. The second upper arm portion 30 is arranged side by side with the lower arm portion 10 on the other side of the lower arm portion 10.

[0110] The negative-side input terminal 15 is formed at one end of the lower arm portion 10. The first positive-side input terminal 25 is formed at one end of the first upper arm portion 20. The first positive-side input terminal 25 is arranged side by side with the negative-side input terminal 15. The second positive-side input terminal 35 is formed at one end of the second upper arm portion 30. The second positive-side input terminal 35 is arranged side by side with the negative-side input terminal 15. The other end of the lower arm portion 10, the other end of the first upper arm portion 20, and the other end of the second upper arm portion 30 are electrically connected to the output terminal 51. One side surface 14a of the second conductor pattern 14 opposes the side surface 23a of the third conductor pattern 23. The other side surface 14b of the second conductor pattern 14 opposes the side surface 33a of the fourth conductor pattern 33. The one side surface 14a of the second conductor pattern 14 is an example of one side surface of the lower arm portion 10. The other side surface 14b of the second conductor pattern 14 is an example of the other side surface of the lower arm portion 10. The side surface 23a of the third conductor pattern 23 is an example of a side surface of the first upper arm portion 20. The side surface 33a of the fourth conductor pattern 33 is an example of a side surface of the second upper arm portion 30.

[0111] According to this structure, the lower arm portion 10 and the first upper arm portion 20 constitute parallel flat plates, and the lower arm portion 10 and the second upper arm portion 30 constitute parallel flat plates. Therefore, the inductance of the power module can be further reduced. Therefore, since the loss of the circuit can be reduced, a smaller semiconductor element can be used to establish the circuit. Therefore, the power module and the entire power conversion device including the power module can be miniaturized and cost reduction can be achieved.

[0112] In the power module of this embodiment, the distance between one side 14a of the second conductor pattern 14 and a side 23a of the third conductor pattern 23 is 5 mm or less. The distance between the other side 14b of the second conductor pattern 14 and a side 33a of the fourth conductor pattern 33 is 5 mm or less. According to this structure, the lower arm portion 10 and the first upper arm portion 20 can more reliably function as parallel plates, and the lower arm portion 10 and the second upper arm portion 30 can more reliably function as parallel plates. Thus, the inductance of the power module can be further reduced.

[0113] In the power module of this embodiment, the lower arm portion 10 has the first conductor pattern 13, the second conductor pattern 14, the first lead frame 16, and the second lead frame 17. The first negative-side semiconductor element 11 and the second negative-side semiconductor element 12 are provided in the first conductor pattern 13. The second conductor pattern 14 is separated from the first conductor pattern 13. The first lead frame 16 is electrically connected to the first negative-side semiconductor element 11 and the second conductor pattern 14. The second lead frame 17 connects the second negative-side semiconductor element 12 and the second conductor pattern 14.

[0114] The first upper arm portion 20 has the third conductor pattern 23 and the third lead frame 26. The first positive-side semiconductor element 21 is provided in the third conductor pattern 23. The third lead frame 26 electrically connects the first positive-side semiconductor element 21 and the first conductor pattern 13.

[0115] The second upper arm portion 30 has the fourth conductor pattern 33 and the fourth lead frame 36. The second positive-side semiconductor element 31 is provided in the fourth conductor pattern 33. The fourth lead frame 36 electrically connects the second positive-side semiconductor element 31 and the first conductor pattern 13.

[0116] The long sides of the first lead frame 16, the second lead frame 17, the third lead frame 26, and the fourth lead frame 36 are parallel to each other. According to this structure, the first lead frame 16 of the lower arm portion 10 and the third lead frame 26 of the first upper arm portion 20 constitute a parallel plate. Further, the second lead frame 17 of the lower arm portion 10 and the fourth lead frame 36 of the second upper arm portion 30 constitute a parallel plate. Thus, the inductance of the power module can be further reduced.

[0117] In the power module of this embodiment, when a current flows through the first upper arm portion 20, a current in a direction parallel to the direction of the current flowing through the first upper arm portion 20 flows through the lower arm portion 10. When a current flows through the second upper arm portion 30, a current in a direction parallel to the direction of the current flowing through the second upper arm portion 30 flows through the lower arm portion 10. According to this structure, the inductance of the power module can be further reduced.

[0118] Embodiment 2.

[0119] A power module according to Embodiment 2 will be described. Figure 11 is a plan view showing a physical structure of the power module according to the present embodiment. As shown in Figure 11 , the power module according to the present embodiment differs from the power module according to Embodiment 1 shown in Figure 1 in that a conductor bridge 40 is provided. In addition, for constituent elements having the same function and action as those of Embodiment 1, the same reference numerals are given and the description thereof is omitted.

[0120] The conductor bridge 40 is a lead frame electrically connecting the first upper arm portion 20 and the second upper arm portion 30 across the lower arm portion 10. The conductor bridge 40 is formed in a plate shape. The conductor bridge 40 has a planar shape of a long rectangular shape longer in one direction. The long side direction of the conductor bridge 40 is orthogonal to the respective long side directions of the first lead frame 16, the second lead frame 17, the third lead frame 26, and the fourth lead frame 36. The long side direction of the conductor bridge 40 is substantially orthogonal to the direction of the current flowing through each of the lower arm portion 10, the first upper arm portion 20, and the second upper arm portion 30. The width of the short side direction of the conductor bridge 40 is 3 mm or more.

[0121] One end portion 40a of the conductor bridge 40 in the long side direction is joined to the surface of the third conductor pattern 23 of the first upper arm portion 20. The other end portion 40b of the conductor bridge 40 in the long side direction is joined to the surface of the fourth conductor pattern 33 of the second upper arm portion 30. The conductor bridge 40 and the second conductor pattern 14 of the lower arm portion 10 oppose each other with a gap in a direction perpendicular to the substrate face of the insulating substrate 60. That is, the conductor bridge 40 and the second conductor pattern 14 constitute parallel flat plates.

[0122] Even if the power module has a symmetrical structure, the positive-side bus bar and the negative-side bus bar provided outside the power module are highly likely to be asymmetric in layout. When the positive-side bus bar and the negative-side bus bar are asymmetric, a potential difference is easily generated in the first upper arm portion 20 and the second upper arm portion 30.

[0123] In the power module according to the present embodiment, the first upper arm portion 20 and the second upper arm portion 30 are electrically connected by the conductor bridge 40. The conductor bridge 40 is a current path for mitigating the potential difference between the first upper arm portion 20 and the second upper arm portion 30. Since the conductor bridge 40 is provided inside the power module, it is less likely to be affected by the magnetic field of the bus bar provided outside the power module. Thus, the current division difference between the first upper arm portion 20 and the second upper arm portion 30 can be mitigated.

[0124] For example, when the current flowing through the second upper arm portion 30 is greater than the current flowing through the first upper arm portion 20, a part of the current flows from the second upper arm portion 30 to the first upper arm portion 20 through the conductor bridge 40 due to the potential difference.

[0125] Here, inFigure 11 In the middle, the second positive side input terminal 35 of the second upper arm 30 is located at the upper right of the conductor bridge 40, and the first positive side semiconductor element 21 of the first upper arm 20 is located at the lower left of the conductor bridge 40. Therefore, the current flowing through the conductor bridge 40... Figure 11 The current flows from the upper right to the lower left. Therefore, the current flowing through conductor bridge 40 is... Figure 11 It has a downward vector component.

[0126] on the other hand, Figure 11 An upward current flows through the second conductor pattern 14 of the lower arm 10. That is, the current flowing through the conductor bridge 40 has a vector component that is parallel to but opposite in direction to the current flowing through the second conductor pattern 14. Therefore, by providing the conductor bridge 40, the effect of reducing inductance can also be achieved.

[0127] As described above, the power module of this embodiment also includes a conductor bridge 40. The conductor bridge 40 spans the lower arm 10 to electrically connect the first upper arm 20 and the second upper arm 30. According to this structure, the shunt difference between the first upper arm 20 and the second upper arm 30 can be reduced, and the inductance of the power module can be further reduced.

[0128] Implementation method 3.

[0129] The power module involved in Implementation Method 3 will be described. Figure 12 This is a perspective view showing a portion of the structure of the power module according to this embodiment. Furthermore, components having the same function and effect as those in Embodiment 1 or 2 are given the same reference numerals and their descriptions are omitted.

[0130] like Figure 12 As shown, in a cross-section cut along the long side of the third lead frame 26, the end 26a of the third lead frame 26 has a T-shaped cross-sectional shape. That is, the third lead frame 26 has a flat portion 26d and a protrusion 26e protruding from the flat portion 26d on the back side of the end 26a in the aforementioned cross-section. The protrusion 26e is bonded to the surface of the first positive electrode side semiconductor element 21. The first lead frame 16, the second lead frame 17, and the fourth lead frame 36 have the same structure as the third lead frame 26.

[0131] An insulating distance must be maintained between each leadframe and the semiconductor chip. According to this embodiment, the distance between the leadframe forming the upper arm and the leadframe forming the lower arm can be brought closer together, unaffected by manufacturing tolerances in the distance between the leadframe joint and the semiconductor element. Therefore, the reduction effect of the combined inductance within the power module can be improved through the interaction of magnetic fields between the leadframes.

[0132] As explained above, in the power module of the present embodiment, each of the first lead frame 16, the second lead frame 17, the third lead frame 26, and the fourth lead frame 36 has a T-shaped cross-sectional shape. According to this structure, it is possible to make the distance between the first lead frame 16 and the third lead frame 26 close, and to make the distance between the second lead frame 17 and the fourth lead frame 36 close. Therefore, it is possible to enhance the interaction of the respective magnetic fields between the first lead frame 16 and the third lead frame 26 and between the second lead frame 17 and the fourth lead frame 36, and thus it is possible to further reduce the inductance of the power module.

[0133] BRIEF DESCRIPTION OF DRAWINGS

[0134] 10 lower arm portion, 10a center line, 11 first negative-side semiconductor element, 11a signal terminal, 12 second negative-side semiconductor element, 12a signal terminal, 13 first conductor pattern, 14 second conductor pattern, 14a, 14b side surface, 15 negative-side input terminal, 16 first lead frame, 16a, 16b end portion, 16c side surface, 17 second lead frame, 17a, 17b end portion, 17c side surface, 20 first upper arm portion, 21 first positive-side semiconductor element, 21a signal terminal, 23 third conductor pattern, 23a side surface, 25 first positive-side input terminal, 26 third lead frame, 26a, 26b end portion, 26c side surface, 26d flat portion, 26e protruding portion, 27 gap, 30 second upper arm portion, 31 second positive-side semiconductor element, 31a signal terminal, 33 fourth conductor pattern, 33a side surface, 35 second positive-side input terminal, 36 fourth lead frame, 36a, 36b end portion, 36c side surface, 37 gap, 40 conductor bridge, 40a, 40b end portion, 50 AC-side arm portion, 51 output terminal, 60 insulating substrate, 80 conduction current, 81 reflux current, 82 conduction current, 83 recovery current, 101, 102 conductor, 103 gap, 104, 105 cylindrical wire, 106, 107, 108, 109 conductor, 110, 111 gap, 112, 113, 114, 115 cylindrical wire, 120 positive-side semiconductor element, 121 negative-side semiconductor element, 122 conduction current, 123 reflux current, 124 conduction current, 125 recovery current.

Claims

1. A power module, characterized by Comprising: a lower arm portion having a first negative-side semiconductor element and a second negative-side semiconductor element; a first upper arm portion having a first positive-side semiconductor element and being arranged side by side with the lower arm portion on one side of the lower arm portion; and a second upper arm portion having a second positive-side semiconductor element and being arranged side by side with the lower arm portion on the other side of the lower arm portion, a negative-side input terminal is formed at one end of the lower arm portion, a first positive-side input terminal arranged side by side with the negative-side input terminal is formed at one end of the first upper arm portion, a second positive-side input terminal arranged side by side with the negative-side input terminal is formed at one end of the second upper arm portion, the other end of the lower arm portion, the other end of the first upper arm portion, and the other end of the second upper arm portion are electrically connected to an output terminal, one side surface of the lower arm portion opposes a side surface of the first upper arm portion, the other side surface of the lower arm portion opposes a side surface of the second upper arm portion, the lower arm portion, the first upper arm portion, and the second upper arm portion are arranged on the same plane, the lower arm portion and the first upper arm portion constitute parallel flat plates, and the lower arm portion and the second upper arm portion constitute parallel flat plates.

2. The power module according to claim 1, wherein a distance between the one side surface of the lower arm portion and the side surface of the first upper arm portion, and a distance between the other side surface of the lower arm portion and the side surface of the second upper arm portion are each 5 mm or less.

3. The power module according to claim 1 or 2, further comprising: a conductor bridge electrically connecting the first upper arm portion and the second upper arm portion across the lower arm portion.

4. The power module according to claim 1 or 2, wherein: the lower arm portion includes a first conductor pattern in which the first negative-side semiconductor element and the second negative-side semiconductor element are arranged, a second conductor pattern separate from the first conductor pattern, a first lead frame electrically connecting the first negative-side semiconductor element and the second conductor pattern, and a second lead frame electrically connecting the second negative-side semiconductor element and the second conductor pattern, the first upper arm portion includes a third conductor pattern in which the first positive-side semiconductor element is arranged, and a third lead frame electrically connecting the first positive-side semiconductor element and the first conductor pattern, the second upper arm portion includes a fourth conductor pattern in which the second positive-side semiconductor element is arranged, and a fourth lead frame electrically connecting the second positive-side semiconductor element and the first conductor pattern.

5. The power module according to claim 4, wherein: a long side direction of each of the first lead frame, the second lead frame, the third lead frame, and the fourth lead frame is parallel to each other.

6. The power module according to claim 4, wherein: each of the first lead frame, the second lead frame, the third lead frame, and the fourth lead frame has a T-shaped cross-sectional shape. ​ 7. The power module according to claim 1 or 2, characterized in that, when a current flows through the first upper arm portion, a current in a direction parallel to a direction of the current flowing through the first upper arm portion flows through the lower arm portion, when a current flows through the second upper arm portion, a current in a direction parallel to a direction of the current flowing through the second upper arm portion flows through the lower arm portion.

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