Power conversion device

Abstract

A power conversion device of the present application includes: a semiconductor package having a semiconductor element and an external terminal electrically connected to the semiconductor element; a wiring substrate having a wiring layer electrically connected to the external terminal via solder; and a pressing member pressing the semiconductor package in a thickness direction of the wiring substrate, the external terminal having an abutting portion protruding toward the wiring substrate from a face of the semiconductor package on the wiring substrate side, the abutting portion abutting against a surface of the wiring substrate.

Description

Technical Field

[0001] This invention relates to power conversion devices. Background Technology

[0002] Double-sided cooling is used in power conversion devices operating at high voltages. In such devices, the semiconductor package mounted on a printed circuit board may develop cracks at its solder joint, the junction between the semiconductor package and the printed circuit board, due to temperature cycling. Therefore, it is necessary to ensure the reliability of the device. As a structure to improve device reliability, for example, Patent Document 1 discloses a structure in which a protrusion is provided at the front end of the external lead of the solder joint for the purpose of providing space for insulation and heat dissipation on a printed circuit board without through holes, and the semiconductor device is mounted on the surface of the printed circuit board.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 3-225944 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] In the technology described in Patent Document 1, since no measures are provided to increase the thickness of the solder joint and maintain a certain structure, the terminals may sink into the solder due to the weight of the semiconductor package, thus thinning the solder joint. Therefore, the increased stress and strain at the solder joint caused by the connection of both sides of the semiconductor package to the heat sink can lead to problems that compromise product reliability.

[0008] Technical solutions to solve technical problems

[0009] The power conversion device includes: a semiconductor package having a semiconductor element and an external terminal electrically connected to the semiconductor element; a wiring substrate having a wiring layer electrically connected to the external terminal via solder; and a pressing member pressing the semiconductor package in the thickness direction of the wiring substrate, the external terminal having an abutting portion protruding from a side of the wiring substrate toward the wiring substrate in the semiconductor package, the abutting portion abutting against the surface of the wiring substrate.

[0010] Invention Effects

[0011] It can provide a power conversion device with improved reliability. Attached Figure Description

[0012] Figure 1This is a cross-sectional view showing the structure of the power conversion device according to Embodiment 1 of the present invention.

[0013] Figure 2 This is a cross-sectional view showing the structure of the power conversion device according to Embodiment 2 of the present invention.

[0014] Figure 3 These are variations 1 and 2.

[0015] Figure 4 This is a cross-sectional view showing the structure of the power conversion device according to Embodiment 3 of the present invention.

[0016] Figure 5 These are variations 3 to 5.

[0017] Figure 6 This is variation example 6.

[0018] Figure 7 This is variation example 7. Detailed Implementation

[0019] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following description and drawings are examples for illustrating the present invention, and appropriate omissions and simplifications have been made to clarify the description. The present invention can also be implemented in various other ways. Unless otherwise specified, each structural element can be single or multiple.

[0020] To facilitate understanding of the present invention, the positions, dimensions, shapes, and extents of the constituent elements shown in the accompanying drawings may not represent their actual positions, dimensions, shapes, or extents. Therefore, the present invention is not necessarily limited to the positions, dimensions, shapes, and extents disclosed in the accompanying drawings.

[0021] (Implementation Method 1 and Overall Structure)

[0022] ( Figure 1 )

[0023] In the power conversion device, the semiconductor package 1 includes a semiconductor element (not shown) and an external terminal 6. Furthermore, the semiconductor package 1 has a conductor plate (not shown) on its upper and lower surfaces in its stacking direction, namely a heat dissipation surface 3a exposed from the sealing resin that has molded and sealed the semiconductor package 1. One heat dissipation surface 3a of the semiconductor package 1 is a connection surface for electrical connection with the wiring layer of the wiring substrate 9. This connection surface is electrically connected to the surface of the wiring substrate 9 via solder. Additionally, the external terminal 6, disposed from the semiconductor package 1 toward the outside, has an abutment portion 5 protruding toward the surface of the wiring substrate 9.

[0024] In semiconductor package 1, external terminal 6 is electrically connected to a semiconductor element. External terminal 6 is electrically connected to the surface (electrode surface) of wiring substrate 9 having a wiring layer via solder. The portion that connects external terminal 6 and wiring substrate 9 to each other via solder is designated as solder connection portion 7. In addition, such connection material is not limited to solder, and sintered materials, metal-resin mixtures, etc., can also be used. Furthermore, wiring substrate 9 can also be a substrate with heat dissipation vias.

[0025] In the semiconductor package 1, the side opposite to the side connected to the wiring substrate 9 by the external terminal 6 is exposed as a heat dissipation surface 3a. This heat dissipation surface 3a is thermally connected to the heat sink 2 via a heat dissipation member 3. The heat sink 2 is a cooling member for dissipating heat from the semiconductor package 1, but also functions as a pressing member that presses the semiconductor package 1 in the thickness direction of the wiring substrate 9. Figure 1 In the semiconductor package 1, heat sinks 2 are provided on both sides of the semiconductor package 1 in the thickness direction of the wiring substrate 9. The upper and lower heat sinks 2 are fastened to each other by fixing screws 4, so that the semiconductor package 1 is pressed from both sides by the heat sinks 2.

[0026] The heat sink 2 is thermally connected to one side of the semiconductor package 1 via the heat dissipation member 3 (first heat conduction member). In addition, the other side of the semiconductor package 1 is thermally connected to the surface of the wiring substrate 9 via the solder connection portion 7 (second heat conduction member).

[0027] The external terminal 6 has an abutment portion 5 protruding from the wiring substrate 9 side of the semiconductor package 1 toward the wiring substrate 9. The abutment portion 5 abuts against the surface of the wiring substrate 9. Furthermore, since it is necessary to retain the area where the solder, as a bonding material, is bonded, the area occupied by the abutment portion 5 in the bonding area of ​​the solder joint 7 is localized. Therefore, when pressure is applied to the semiconductor package 1 from the heat sink 2, the thinning of the solder thickness in the solder joint 7 can be suppressed, and crack propagation can be suppressed by mitigating the stress and strain of the solder joint 7. In other words, the abutment portion 5 can limit the thickness of the solder in the solder joint 7.

[0028] In the wiring substrate 9, when a heat dissipation via is formed that extends from the upper surface of the substrate to the lower surface and conducts heat in the thickness direction, a plurality of such heat dissipation vias are formed in the wiring substrate 9. The heat dissipation vias are formed at least in the region that overlaps with the heat dissipation surface 3a of the lower surface of the semiconductor package 1 in the thickness direction.

[0029] Furthermore, the side of the wiring substrate 9 opposite to the connection surface of the semiconductor package 1 is thermally connected to the heat sink 2 via a heat dissipation member 3. Such a heat dissipation member 3 uses a thermally conductive component such as silicone resin containing thermally conductive filler or a heat sink.

[0030] The wiring substrate 9 incorporates multiple wiring layers (not shown) for constructing the inverter circuit, including positive wiring, negative wiring, AC wiring, and gate wiring for controlling the semiconductor package drive. In the wiring substrate 9, to carry large currents, the positive wiring, negative wiring, and AC wiring constituting the main circuit can use thick copper wiring with a thickness exceeding 100 μm.

[0031] As a semiconductor element integrated into semiconductor package 1, a field-effect transistor made of SiC, a wide-bandgap semiconductor, is used. Alternatively, other semiconductor elements such as IGBTs made of Si can also be used for such a semiconductor element.

[0032] In this embodiment, although a double-sided cooling structure with heat dissipation surfaces 3a formed on both sides of the semiconductor package 1 is described, the present invention can also be applied to a single-sided cooling semiconductor package 1.

[0033] The abutment portion 5 is a convex shape protruding from the side of the wiring substrate 9 in the outer terminal 6, but this shape can be other shapes as long as it can limit the thickness of the connecting material such as solder. Furthermore, the abutment portion 5 can also be formed, for example, by embossing the outer terminal 6 from the side opposite to the wiring substrate 9 towards the wiring substrate 9. Moreover, the abutment portion 5 is not limited to a columnar protrusion, but can also be conical or hemispherical. Furthermore, multiple abutment portions 5 can be provided in each outer terminal 6.

[0034] (Implementation Method 2)

[0035] ( Figure 2 )

[0036] The wiring substrate 9 has a substrate opening 9a for mounting the semiconductor package 1 on the wiring substrate 9. The semiconductor package 1 is exposed on the side of the wiring substrate 9 opposite to the connection side of the external terminal 6 and the wiring substrate 9 by being mounted on the wiring substrate 9 with the substrate opening 9a.

[0037] Heat sinks 2 are respectively disposed on both sides of the semiconductor package 1 via heat dissipation members 3, which serve as heat conduction members. The heat dissipation members 3 may be, for example, silicone resin containing thermally conductive fillers. Alternatively, sheet-shaped heat conduction members may be used instead.

[0038] The heat sink 2 is, for example, a refrigerant flow path through which refrigerant flows, and is a pressing member that presses the semiconductor package 1 against both sides of the wiring substrate 9 in the thickness direction. The heat sink 2 is fastened to each other by fixing screws 4, thereby being pressed and fixed against the heat dissipation surfaces 3a provided on both sides of the semiconductor package 1. As a result, since the heat dissipation surfaces 3a on both sides of the semiconductor package 1 are thermally connected to the heat sink 2, the heat generated from the semiconductor package 1 is dissipated to the heat sink 2 via the heat dissipation surfaces of the semiconductor package 1 and the heat dissipation member 3.

[0039] Furthermore, in such a structure, there is a problem that the thickness of the solder connection portion 7 becomes thinner due to the weight of the semiconductor package 1 body. However, since the external terminal 6 is provided with an abutment portion 5 that protrudes relative to the surface of the wiring substrate 9, it is possible to ensure that the solder thickness of the solder connection portion 7 is above a certain value, thereby improving the reliability of the power conversion device.

[0040] (Modified Example 1, Modified Example 2)

[0041] ( Figure 3 )

[0042] Figure 2 (a) is a modified example 1 of the power conversion device of the present invention. Figure 2 (b) is variation 2. Additionally, in Figure 3 The variation shown in the figure applies the method used in... Figure 2 The wiring substrate 9 described herein has a substrate opening 9a, but it can also be applied to... Figure 1 The wiring substrate 9 does not have a substrate opening 9a.

[0043] At the junction 5 Figure 1 and Figure 2 In the structure shown, since the solder is formed inside the solder joint 7, the solder will be located between the front end of the contact portion 5 and the surface of the wiring substrate 9. The thickness of the solder in this area will be locally thinner, potentially compromising reliability. However, in Figure 3 (a) and Figure 3 In the modified example shown in (b), the contact portion 5 is not formed inside the solder in the planar direction, but is formed on the outside. As a result, the solder thickness of the solder connection portion 7 does not become thinner locally, and the thickness of the solder connection portion 7 can be made thicker and kept constant, thus improving reliability.

[0044] exist Figure 3 In Modification 1 shown in (a), the abutment portion 5 is formed outside the solder and is positioned closer to the semiconductor package 1 than the solder connection portion 7. As a result, since the solder connection portion 7 is exposed on the terminal front end side, visual inspection of the solder connection portion 7 becomes easier.

[0045] In addition, Figure 3 In Modification 2 shown in (b), the abutment portion 5 is formed outside the solder and is positioned further away from the solder connection portion 7 in the planar direction, with reference to the semiconductor package 1. By positioning the abutment portion 5 further away from the semiconductor package 1 than the solder placement location, the abutment portion 5 can be independent of the surface of the wiring substrate 9 regardless of the solder position or thickness, thus suppressing deviations of the semiconductor package 1 in the thickness direction.

[0046] (Implementation Method 3)

[0047] ( Figure 4 )

[0048] The wiring substrate 9 has a through hole 13 that is electrically connected to the wiring layer. The abutment portion 5 provided on the external terminal 6 abuts against the opening edge 13a of the through hole 13 provided on the wiring substrate 9. In addition, the external terminal 6 has a protrusion 5a that protrudes into the through hole 13 from the opening edge of the through hole 13 and the abutment portion 5.

[0049] The protrusion 5a is joined to the inner periphery of the through hole 13 by solder. The connection between the protrusion 5a and the inner periphery of the through hole 13 is provided as a solder connection portion 7. Thus, in addition to the solder connection portion 7 on the surface of the wiring substrate 9, a solder connection portion 7 is also provided inside the through hole 13, thereby increasing the bonding area of ​​the solder connection portion 7 and further improving the reliability of the device.

[0050] Furthermore, the external terminal 6 has a bent portion 12 between the solder joint 7 and the semiconductor package 1. This reduces the stress applied to the solder joint 7 and improves reliability. Additionally, in Figure 4 The structure shown in the diagram uses Figure 2 The wiring substrate 9 with opening 9a described herein can also be applied to... Figure 1 The wiring substrate 9 does not have a substrate opening 9a.

[0051] (Variations 3 to 5)

[0052] ( Figure 5 )

[0053] Figure 5 (a) is variation 3. Figure 5 (b) is variation 4. Figure 5 (c) is a variation of example 5. For example... Figure 5 As shown in (a), the abutting portion 5 of the external terminal 6 may also abut only a portion of the opening edge 13a of the through hole 13. In this case, the portion of the solder connection portion 7 disposed between the external terminal 6 and the surface of the wiring substrate 9 and the portion disposed inside the through hole 13 may be integral. Furthermore, as Figure 5 As shown in (b), the structure of the external terminal 6 may also be one where the bent portion 12 is not provided. Furthermore, as... Figure 4 As shown in (c), the protrusion 5a may not be a structure that protrudes from the abutment portion 5, but rather a structure that protrudes from the external terminal 6 into the through hole 13. In this case, the portion of the solder connection portion 7 provided between the external terminal 6 and the surface of the wiring substrate 9 and the portion provided inside the through hole 13 may be integral.

[0054] (Variation Example 6)

[0055] ( Figure 6 )

[0056] The wiring substrate 9 may also have multiple substrate openings 9a. Furthermore, semiconductor packages 1 are respectively mounted / embedded in these multiple substrate openings 9a. This structure is suitable for cases where multiple semiconductor packages 1 are mounted corresponding to the switching elements of each arm constituting a three-phase inverter circuit.

[0057] Furthermore, since multiple switching elements constituting each arm can be used in parallel, they can carry large currents. Additionally, integrating multiple semiconductor packages 1 onto a single wiring substrate 9 also contributes to the miniaturization of the overall device. Moreover, the power conversion device of this invention is not limited to having only one wiring substrate 9; multiple wiring substrates 9 can also be used.

[0058] Even with this structure, the thickness deviation of the solder joint 7 of each semiconductor package 1 can be suppressed by providing the abutment portion 5 on the external terminal 6. Furthermore, by suppressing the configuration deviation of the semiconductor package 1, the deviation in the spacing between the semiconductor package 1 and the heat sink 2 can also be suppressed, as well as the deviation in heat dissipation performance. Moreover, by mounting multiple semiconductor packages 1 in the in-plane direction of the wiring substrate 9, the load applied to each semiconductor package 1 can be reduced, thereby improving the reliability of the power conversion device.

[0059] (Variation Example 7)

[0060] ( Figure 7 )

[0061] The wiring substrate 9 has a second abutting portion 11 that protrudes from the surface of the wiring substrate 9 toward the external terminal 6. In this way, the abutting portion 5 protruding from the external terminal 6 toward the wiring substrate 9 and the abutting portion 5 protruding from the wiring substrate 9 toward the external terminal 6 can further suppress the thickness deviation of the solder joint portion 7 and improve the reliability of the power conversion device.

[0062] According to the embodiments of the present invention described above, the following effects are achieved.

[0063] (1) The power conversion device includes: a semiconductor package 1 having a semiconductor element and an external terminal 6 electrically connected to the semiconductor element; a wiring substrate 9 having a wiring layer electrically connected to the external terminal 6 via solder; and a pressing member 2 pressing the semiconductor package 1 in the thickness direction of the wiring substrate 9, wherein the external terminal 6 has an abutting portion 5 protruding from the side of the wiring substrate 9 toward the wiring substrate 9 in the semiconductor package 1, and the abutting portion 5 abuts against the surface of the wiring substrate 9. Thus, a power conversion device with improved reliability can be provided.

[0064] (2) The contact portion 5 is provided on the outside of the solder in the planar direction. As a result, the thickness of the solder connection portion 7 can be increased and kept constant, thus improving reliability.

[0065] (3) The contact portion 5 is positioned closer to the semiconductor package 1 than the solder in the planar direction. As a result, visual inspection of the solder connection portion 7 becomes easier.

[0066] (4) The contact portion 5 is located in the planar direction at a position farther than the solder relative to the semiconductor package 1. As a result, deviations of the semiconductor package 1 in the thickness direction can be suppressed.

[0067] (5) The wiring substrate 9 has a through hole 13 electrically connected to the wiring layer, the abutting portion 5 abuts against the opening edge 13a of the through hole 13, and the external terminal 6 has a protrusion 5a electrically connected to the inner periphery of the through hole 13. As a result, the bonding area of ​​the solder joint 7 is increased, which can improve reliability.

[0068] (6) The wiring substrate 9 has a substrate opening 9a for mounting the semiconductor package 1. The semiconductor package 1 is exposed in the wiring substrate 9 on the side opposite to the connection side with the external terminal 6. The pressing member 2 is thermally connected to both sides of the semiconductor package 1 in the thickness direction via the heat conduction member 3. As a result, since the thickness of the solder connection portion 7 can be ensured to be above a certain value by the contact portion 5, the reliability is improved.

[0069] (7) The pressing member 2 is thermally connected to one side of the semiconductor package 1 via the first heat conduction member 3, and the other side of the semiconductor package 1 is thermally connected to the surface of the wiring substrate 9 via the second heat conduction member. As a result, the thermal stress applied to the solder joint 7 is reduced, and the reliability is improved.

[0070] (8) The semiconductor package 1 is provided for each of the plurality of substrate openings 9a. As a result, the load applied to each semiconductor package 1 is reduced and the reliability is improved.

[0071] (9) The wiring substrate 9 has a second abutment portion 11 that protrudes from the surface of the wiring substrate 9 toward the external terminal 6. As a result, it is possible to ensure that the thickness of the solder joint portion 7 is above a certain value, thereby improving reliability.

[0072] Furthermore, the present invention is not limited to the embodiments described above, and various modifications or combinations of other structures can be made without departing from its spirit. Additionally, the present invention is not limited to having all the structures described in the above embodiments, but also includes structures obtained by deleting a portion of the structure.

[0073] Label Explanation

[0074] 1. Semiconductor Packaging

[0075] 2 Radiators

[0076] 3. Heat dissipation components

[0077] 3a Heat dissipation surface

[0078] 4. Fixing screws

[0079] 5 abutment part

[0080] 5a Protrusion

[0081] 6 external terminals

[0082] 7 Solder joint

[0083] 9 Wiring substrate

[0084] 9a. Substrate opening

[0085] 11 Second landing section

[0086] 12. Bend

[0087] 13 Through holes

[0088] 13a Opening edge.

Claims

1. A power conversion device, characterized in that, include: A semiconductor package having a semiconductor element and external terminals electrically connected to the semiconductor element; A wiring substrate having a wiring layer electrically connected to the external terminals via solder; as well as A pressing member presses the semiconductor package in the thickness direction of the wiring substrate. The external terminal has an abutting portion that protrudes from the wiring substrate side towards the wiring substrate in the semiconductor package. The abutting portion abuts against the surface of the wiring substrate.

2. The power conversion device as described in claim 1, characterized in that, The abutting portion is disposed on the outside of the solder in the planar direction.

3. The power conversion device as described in claim 2, characterized in that, The abutting portion is positioned closer to the semiconductor package side than the solder in the planar direction.

4. The power conversion device as described in claim 2, characterized in that, The abutting portion is positioned in the planar direction at a location farther than the solder relative to the semiconductor package.

5. The power conversion device as described in claim 1, characterized in that, The wiring substrate has through holes that are electrically connected to the wiring layer. The abutting part abuts against the opening edge of the through hole. The external terminal has a protrusion that is electrically connected to the inner periphery of the through hole.

6. The power conversion device as described in claim 1, characterized in that, The wiring substrate has a substrate opening for mounting the semiconductor package. The semiconductor package is exposed in the wiring substrate on the side opposite to the connection side of the external terminal. The pressing member is thermally connected to both sides of the semiconductor package in the thickness direction via a heat-conducting member.

7. The power conversion device as claimed in claim 1, characterized in that, The pressing member is thermally connected to one side of the semiconductor package via a first thermally conductive member. The other side of the semiconductor package is thermally connected to the surface of the wiring substrate via a second thermally conductive member.

8. The power conversion device as described in claim 6, characterized in that, The semiconductor package is configured for each of the plurality of substrate openings.

9. The power conversion device as claimed in claim 1, characterized in that, The wiring substrate has a second abutment portion protruding from the surface of the wiring substrate toward the external terminal.

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