Power conversion device

Abstract

To provide a power conversion device that suppresses warping of a wiring board and increases a distance between conductors.SOLUTION: A power conversion device includes: a semiconductor package 10 in which a semiconductor element 1 forming upper and lower arm circuits are built; and a wiring board 50, in which the semiconductor package is provided, having a plurality of wiring layers, in which the semiconductor element has a first main electrode and a second main electrode on the opposite surface of the first main electrode, and the semiconductor package has a first conductor 11 connected to the first main electrode of the semiconductor element, and a high potential of the upper and lower arm circuit, a second conductor 12 connected to the second main electrode of the semiconductor element, and a low potential of the upper and lower arm circuit, and a sealing member 14 that seals the first conductor, the second conductor, and the semiconductor element. The first conductor is connected to a first surface 51 of the wiring board by a first terminal 16 protruding from the sealing member, and the second conductor has an exposed surface 12E exposed from the sealing member on the surface opposite to the side to which the semiconductor element is bonded, and a connecting conductor 18 that connects a second surface 52 of the wiring board and the exposed surface of the second conductor.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a power conversion device.

Background Art

[0002] Power conversion devices are used in various industrial fields, and there is a demand for higher efficiency and smaller size. Patent Document 1 discloses a semiconductor device including one or a plurality of power elements having main terminals on upper and lower surfaces, first and second conductors that are respectively connected to the main terminals on the upper and lower surfaces of the power element, conduct a main current, and face each other with a predetermined gap therebetween, a drive IC that controls the power element, an interposer that connects the drive IC and the power element, and a signal terminal connected to the drive IC. The interposer has a gate wiring pattern connected to the gate terminal of the power element and is configured to be inserted and disposed in the gap between the first conductor and the second conductor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the invention described in Patent Document 1, there is room for consideration in countermeasures against warping of the wiring board.

Means for Solving the Problems

[0005] The power conversion device according to the first aspect of the present invention includes a semiconductor package in which a semiconductor element constituting an upper arm or a lower arm of an upper and lower arm circuit is incorporated, and a wiring board on which the semiconductor package is mounted and which has a plurality of wiring layers electrically connected to the semiconductor package. The semiconductor element has a first main electrode and a second main electrode on a surface opposite to the first main electrode. The semiconductor package includes a first conductor connected to the first main electrode of the semiconductor element and a high potential side of the upper and lower arm circuits, a second conductor connected to the second main electrode of the semiconductor element and a low potential side of the upper and lower arm circuits, and a sealing member that seals the first conductor, the second conductor, and the semiconductor element. The first conductor is connected to the first surface of the wiring board via a first terminal protruding from the sealing member. The second conductor has an exposed surface exposed from the sealing member on a surface opposite to the side where the semiconductor element is joined, and the wiring board further includes a connection conductor that electrically connects the second surface, which is the surface opposite to the first surface of the wiring board, and the exposed surface of the second conductor.

Advantages of the Invention

[0006] According to the present invention, warping of the wiring board can be suppressed and the distance between conductors can be increased.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0008] - Embodiment - Hereinafter, an embodiment of a power conversion device will be described with reference to FIGS. 1 to 4.

[0009] FIG. 1 is an electrical circuit diagram of a power conversion device 100. The power conversion device 100 includes a U-phase circuit 100U that processes the U-phase, a V-phase circuit 100V that processes the V-phase, and a W-phase circuit 100W that processes the W-phase. Since the configurations of the circuits for each phase are the same, only the U-phase circuit 100U will be described here. The U-phase circuit 100U includes four sets of upper and lower arms, and each arm has a semiconductor element 1. The U-phase circuit 100U includes a positive electrode wiring 71 at the upper part shown in the figure, an AC wiring 72 at the center shown in the figure, a negative electrode wiring 73 at the lower part shown in the figure, and a ceramic capacitor 75 on the left side shown in the figure. The two enclosures shown inside the V-phase circuit 100V are the upper arm element circuit 1U and the lower arm element circuit 1D. Hereinafter, the structures of the upper arm element circuit 1U and the lower arm element circuit 1D will be described.

[0010] FIG. 2 is a cross-sectional view of the upper arm element circuit 1U and the lower arm element circuit 1D. From FIG. 2 onwards, in order to clarify the correlation between the drawings, XYZ axes orthogonal to each other are shown. In FIG. 2, the plus side of the X-axis is the right side shown in the figure, the plus side of the Y-axis is the back side shown in the figure, and the plus side of the Z-axis is the upper side shown in the figure. Hereinafter, the Z-axis direction may be referred to as the "first direction" in some cases, and the X-axis direction may be referred to as the "second direction" in some cases.

[0011] The power conversion device 100 has heat dissipation members 500 sandwiching the upper and lower sides of a flat wiring board 50. The heat dissipation member 500 may be a heat dissipation fin or may have a cooling medium flowing inside. The heat dissipation member 500 includes an upper heat dissipation member 500U and a lower heat dissipation member 500D. The wiring board 50 is a multilayer board having a plurality of wiring layers. The first main circuit wiring 61 is formed on the first layer of the wiring board 50. The second main circuit wiring 62 is formed on the fourth layer of the wiring board 50, that is, the lowermost layer. When FIG. 2 shows the upper arm element circuit 1U, the first main circuit wiring 61 corresponds to the positive electrode wiring 71 and the second main circuit wiring 62 corresponds to the AC wiring 72. When FIG. 2 shows the lower arm element circuit 1D, the first main circuit wiring 61 corresponds to the AC wiring 72 and the second main circuit wiring 62 corresponds to the negative electrode wiring 73.

[0012] The surface of the wiring board 50 on the positive side of the Z-axis is referred to as the first surface 51, and the surface of the wiring board 50 on the negative side of the Z-axis is referred to as the second surface 52. The wiring board 50 has a through hole 50T penetrating in the Z-axis direction, and the semiconductor package 10 is arranged in the through hole 50T. The semiconductor package 10 includes a semiconductor element 1, a first conductor 11, a second conductor 12, a semiconductor element bonding member 13, a sealing member 14, a signal terminal 17, and a first terminal 16.

[0013] The semiconductor element 1 is flat, has a first main electrode 1M on the positive side of the Z-axis, and has a second main electrode 1S on the negative side of the Z-axis. The first main electrode 1M is connected to the first conductor 11 via the semiconductor element bonding member 13. The second main electrode 1S is connected to the second conductor 12 via the semiconductor element bonding member 13. That is, the semiconductor element 1 has its upper part in contact with the first conductor 11, its lower part in contact with the second conductor 12, and its side surface surrounded by the sealing member 14.

[0014] The first conductor 11 is electrically connected to the first terminal 16. The surface of the first conductor 11 on the positive side of the Z-axis is exposed from the sealing member 14, and this exposed surface is in contact with the upper heat dissipation member 500U via the semiconductor package bonding member 23. Therefore, when the heat generated by the semiconductor element 1 is chased to the positive side of the Z-axis, the heat from the semiconductor element 1 reaches the upper heat dissipation member 500U via the semiconductor element bonding member 13, the first conductor 11, and the semiconductor package bonding member 23 in the direction from the semiconductor element 1 to the positive side of the Z-axis.

[0015] The second conductor 12 has a second conductor exposed surface 12E, which is the surface on the minus side of the Z-axis, exposed from the sealing member 14 and contacts the connection conductor 18 via the semiconductor package joining member 23. The connection conductor 18 connects the left and right wiring boards 50 sandwiching the through-hole 50T via the terminal connection portion 40. The connection conductor 18 contacts the lower heat dissipation member 500D via the semiconductor package joining member 23. Therefore, when the heat generated by the semiconductor element 1 moves toward the minus side of the Z-axis, starting from the semiconductor element 1 toward the minus side of the Z-axis, it reaches the lower heat dissipation member 500D via the semiconductor element joining member 13, the second conductor 12, the semiconductor package joining member 23, the connection conductor 18, and the semiconductor package joining member 23.

[0016] One end of the first terminal 16 is connected to the first conductor 11, and the other end is connected to the first main circuit wiring 61 via the terminal connection portion 40. Since the first conductor 11 is surrounded by the sealing member 14, a part of the first terminal 16 connected to the first conductor 11 is also covered by the sealing member 14, and the other end protruding from the sealing member 14 is connected to the first main circuit wiring 61. One end of the signal terminal 17 is connected to the signal electrode of the semiconductor element 1 by wire bonding, and the other end is connected to the first main circuit wiring 61 of the wiring board 50.

[0017] The wiring board 50 is provided with an interlayer connection portion (not shown) for electrically connecting different layers. The interlayer connection portion is a through-hole via or the like that penetrates a plurality of layers in the thickness direction of the wiring board 50. By providing a large number of interlayer connection portions, the cross-sectional area of the current flowing in the cross-sectional direction of the wiring board 50 can be increased. As a result, the electrical resistance is reduced and heat generation in the wiring is decreased. Further, since the interlayer connection portion improves the heat transfer property of the wiring board 50 in the Z-axis direction, the rise in the wiring temperature can be suppressed. The semiconductor element joining member 13, the semiconductor package joining member 23, and the terminal connection portion 40 are solder or the like. In this embodiment, there are a plurality of each of the semiconductor element joining member 13, the semiconductor package joining member 23, and the terminal connection portion 40. These are only using the same reference numerals to indicate that the materials are the same, and do not indicate that the same reference numerals are physically integrated.

[0018] The first terminal 16, the signal terminal 17, and the connection conductor 18 are shown in FIG. 2 as being connected to the wiring board 50 at a single point. However, in reality, as will be described later, they also exist in the Y-axis direction and are connected to the wiring board 50 at a plurality of positions. Further, the positions where the first terminal 16 and the connection conductor 18 contact the wiring board 50 are the same coordinates not only in the X-axis coordinate but also in the depth-direction Y-axis coordinate, and only the Z-axis coordinate is different. Similarly, the positions where the signal terminal 17 and the connection conductor 18 contact the wiring board 50 are the same coordinates not only in the X-axis coordinate but also in the depth-direction Y-axis coordinate, and only the Z-axis coordinate is different.

[0019] FIG. 3 is a plan view of the upper arm element circuit 1U and the lower arm element circuit 1D. However, in FIG. 3, the heat dissipation member 500 and the semiconductor package joining member 23 are removed from the configuration shown in FIG. 2. There are four first terminals 16 and four signal terminals 17, respectively, which extend in the X-axis direction and are connected to the wiring board 50. Each of the first terminals 16 and the signal terminals 17 has a plurality of parallel linear shapes and can thus be called "comb-shaped". Since the first terminals 16 and the signal terminals 17 are each connected to the wiring board 50 at a plurality of positions, specifically, at four points each, the stress generated in each of the first terminals 16 and the signal terminals 17 can be reduced. Further, since the first terminal 16 connects the first conductor 11 and the wiring board 50 in a straight line, the inductance can be reduced.

[0020] FIG. 4 is a bottom view of the upper arm element circuit 1U and the lower arm element circuit 1D. However, in FIG. 3, the heat dissipation member 500 and the semiconductor package joining member 23 are removed from the configuration shown in FIG. 2. FIG. 4 shows a perspective opposite to that of FIG. 3. The connection conductor 18 branches into four on each of the +X-axis side and the -X-axis side with respect to the semiconductor element 1, and each is connected to the second main circuit wiring 62 of the wiring board 50. On the +X-axis side with respect to the semiconductor element 1, when the connection conductor 18 moves in the +Z-axis direction from the position where it contacts the wiring board 50, the first terminal 16 reaches the position where it contacts the wiring board 50. By providing connection portions above and below the wiring board 50, the current path can be shortened. Also, as the number of terminals increases, the tolerance number of the magnetic force increases, so the inductance can be significantly reduced. Further, since the first terminal 16 and the connection conductor 18 sandwich the wiring board 50 at the same X and Y coordinates, deformation of the wiring board 50, specifically warping of the wiring board 50, can be prevented.

[0021] On the -X-axis side with respect to the semiconductor element 1, when the connection conductor 18 moves in the +Z-axis direction from the position where it contacts the wiring board 50, the signal terminal 17 reaches the position where it contacts the wiring board 50. Since the signal terminal 17 and the connection conductor 18 sandwich the wiring board 50 at the same X and Y coordinates, deformation of the wiring board 50, specifically warping of the wiring board 50, can be prevented.

[0022] According to the above-described embodiment, the following operational effects can be obtained. (1) The power conversion device 100 includes a semiconductor package 10 incorporating a semiconductor element 1 that constitutes an upper arm element circuit 1U or a lower arm element circuit 1D, and a wiring board 50 on which the semiconductor package 10 is mounted and which has a plurality of wiring layers electrically connected to the semiconductor package 10. The semiconductor package 10 includes a first conductor 11 connected to the first main electrode 1M of the semiconductor element 1 and the high potential side of the upper and lower arm circuits, a second conductor 12 connected to the second main electrode 1S of the semiconductor element 1 and the low potential side of the upper and lower arm circuits, and a sealing member 14 that seals the first conductor 11, the second conductor 12, and the semiconductor element 1. The first conductor 11 is connected to the first main circuit wiring 61 on the first surface 51 of the wiring board 50 via a first terminal 16 protruding from the sealing member 14. The second conductor 12 has a second conductor exposed surface 12E that is an exposed surface exposed from the sealing member 14 on the surface opposite to the Z-axis plus side, that is, the Z-axis minus side, which is the side where the semiconductor element 1 is joined. The power conversion device 100 includes a connection conductor 18 that electrically connects the second surface 52, which is the surface opposite to the first surface 51 of the wiring board 50, and the second conductor exposed surface 12E. Therefore, by forming terminals separately above and below the board, the deformation during temperature change above and below the board is balanced, and warping of the wiring board 50 can be suppressed. Since the warping of the wiring board 50 is suppressed, the reliability of the terminal connection portion 40 that connects the first terminal 16 and the first main circuit wiring 61, and the terminal connection portion 40 that connects the connection conductor 18 and the second main circuit wiring 62 is improved. However, the improvement in reliability mentioned here means that it is difficult for a strong load to occur and it is difficult to be destroyed. Also, by forming terminals separately above and below the board, the distance between the first conductor 11 and the second conductor 12 can be increased.

[0023] (2) The semiconductor package 10 is disposed in a through hole 50T that penetrates the wiring board 50 in the Z-axis direction. The connection conductor 18 has connection portions with the second surface 52 of the wiring board 50 on both sides of the semiconductor package 10 in the X-axis direction. Therefore, by providing connection portions on both sides of the semiconductor package 10 in the X-axis direction and on both sides in the Z-axis direction, the deformation during temperature change above and below the wiring board 50 is balanced, and warping of the wiring board 50 can be suppressed.

[0024] (3) The semiconductor package 10 has a signal terminal 17 that is connected to the first surface 51 of the wiring board 50 on the side opposite to the first terminal 16 in the X-axis direction. Therefore, the distance between the first terminal 16 and the signal terminal 17 can be increased.

[0025] (4) Each of the first terminal 16, the connection conductor 18, and the signal terminal 17 is connected to the wiring board 50 by a plurality of paths. Therefore, the current paths can be dispersed into a plurality to reduce the amount of heat generation. Also, since the connections to the wiring board 50 are dispersed into a plurality, the stress per terminal can be reduced. Further, since the number of magnetic flux linkages increases with an increase in the number of terminals, the inductance can be significantly decreased.

[0026] (5) Each of the first terminal 16, the connection conductor 18, and the signal terminal 17 forms a terminal in a comb shape and is connected to the wiring board 50. Therefore, the current path can be shortened and the inductance can be decreased.

[0027] (6) The first terminal 16 and the signal terminal 17 are connected to the wiring board 50 at positions overlapping the terminals of the connection conductor 18 in the Z-axis direction. Therefore, since the wiring board 50 is sandwiched in the Z-axis direction, the deformation during temperature change is balanced and the warping of the wiring board 50 can be suppressed.

[0028] (7) The wiring board 50 includes a first main circuit wiring 61 connected to the first terminal 16, a signal wiring 63 connected to the signal terminal 17, and a second main circuit wiring 62 connected to the connection conductor 18. Therefore, the components of the power conversion device 100 can be integrated.

[0029] (Modification Example 1) FIG. 5 is a cross-sectional view of the upper arm element circuit 1U and the lower arm element circuit 1D in the modified example. In FIG. 5, the description of the reference numerals common to FIG. 2 is omitted. The difference from the cross-sectional view in the embodiment shown in FIG. 2 is that each of the first terminal 16, the signal terminal 17, and the connection conductor 18 has a terminal bending portion 90 where it is bent. The terminal bending portion 90 changes the position of each terminal in the Z-axis direction. The first terminal 16 has a first terminal bending portion 90-16 at a height H1 in the Z-axis direction. The signal terminal 17 has a signal terminal bending portion 90-17 at a height H2 in the Z-axis direction. The connection conductor 18 has a first connection conductor bending portion 90-1 at a height H3 in the Z-axis direction and a second connection conductor bending portion 90-2 at a height H4 in the Z-axis direction.

[0030] It is desirable that the height H1 and the height H2 be equal, and it is desirable that the height H3 and the height H4 be equal. However, H1 and H3 do not have to be equal. Also, all of the heights of H1 to H4 may be different. In this modified example, since the rigidity of each terminal is reduced by the terminal bending portion 90, the stress at the terminal connection portion 40 can be reduced.

[0031] According to this modified example 1, the following operational effects can be obtained. (8) The first terminal 16, the signal terminal 17, and the connection conductor 18 have a terminal bending portion 90 that bends the terminal vertically. Therefore, since the rigidity of each terminal is reduced by the terminal bending portion 90, the stress at the terminal connection portion 40 can be reduced.

[0032] (Modified Example 2) FIG. 6 is a plan view of the upper arm element circuit 1U and the lower arm element circuit 1D in the modified example 2. FIG. 6 corresponds to FIG. 3 in the embodiment. In the above-described embodiment, each of the first terminal 16, the signal terminal 17, and the connection conductor 18 was comb-shaped, but it is sufficient that there are a plurality of paths. For example, the semiconductor package 10 and the wiring board 50 may be connected obliquely instead of being connected at the shortest distance, or the terminal may be bent.

[0033] Each of the above-described embodiments and modifications may be combined. Although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other aspects conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

Explanation of Reference Numerals

[0034] 1: Semiconductor element 1D: Lower arm element circuit 1M: First main electrode 1S: Second main electrode 1U: Upper arm element circuit 10: Semiconductor package 11: First conductor 12: Second conductor 14: Sealing member 16: First terminal 17: Signal terminal 18: Connection conductor 50: Wiring board 50T: Through hole 90: Terminal bending portion 100: Power conversion device

Claims

1. A semiconductor package incorporating a semiconductor element that constitutes an upper arm or a lower arm of an upper and lower arm circuit, and a wiring board on which the semiconductor package is mounted and that has a plurality of wiring layers electrically connected to the semiconductor package, wherein the semiconductor element has a first main electrode and a second main electrode on a surface opposite to the first main electrode, the semiconductor package includes a first conductor connected to the first main electrode of the semiconductor element and the high potential side of the upper and lower arm circuit, a second conductor connected to the second main electrode of the semiconductor element and the low potential side of the upper and lower arm circuit, a sealing member that seals the first conductor, the second conductor, and the semiconductor element, the first conductor is connected to the first surface of the wiring board via a first terminal protruding from the sealing member, the second conductor has an exposed surface exposed from the sealing member on a surface opposite to the side where the semiconductor element is joined, A power conversion device further comprising a connection conductor that electrically connects the second surface, which is the surface opposite to the first surface of the wiring board, and the exposed surface of the second conductor.

2. The power conversion device according to claim 1, wherein the semiconductor package is disposed in a through hole that penetrates the wiring board in a first direction, the connection conductor has connection portions with the second surface of the wiring board on both sides in a second direction orthogonal to the first direction in the semiconductor package.

3. The power conversion device according to claim 1, wherein the semiconductor package is disposed in a through hole that penetrates the wiring board in a first direction, the semiconductor package further includes a signal terminal that connects to the first surface of the wiring board on the side opposite to the first terminal in a second direction orthogonal to the first direction.

4. The power conversion device according to claim 3, each of the first terminal, the connection conductor, and the signal terminal is connected to the wiring board by a plurality of paths.

5. The power conversion device according to claim 4, each of the first terminal, the connection conductor, and the signal terminal forms terminals in a comb shape and connects to the wiring board.

6. The power conversion device according to claim 4, each of the first terminal and the signal terminal is connected to the wiring board at a position overlapping the terminal of the connection conductor in the first direction.

7. A power conversion device according to claim 3, wherein the first terminal, the signal terminal, and the connection conductor each have a terminal bending portion that changes the position of each terminal in the first direction.

8. A power conversion device according to claim 7, wherein the distance in the first direction formed by the terminal bending portion at the first terminal is equal to the distance in the first direction formed by the terminal bending portion at the signal terminal, the connection conductor has a first connection conductor bending portion that is the first terminal bending portion and a second connection conductor bending portion that is the second terminal bending portion on both sides in a second direction orthogonal to the first direction of the semiconductor package, and a distance in the first direction formed by the first connection conductor bending portion is equal to a distance in the first direction formed by the second connection conductor bending portion.

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