Power module and electric power conversion device

Abstract

A main frame part (6Aa) has a first end section (ED1) having a first dimension along a second direction intersecting a first direction. A main terminal part (6Ab) of a lead frame (6A) is directly adjacent to the main frame part (6Aa) in a third direction intersecting the first and second directions. The main terminal part (6Ab) has a second end section (ED2) connected to the first end section (ED1) of the main frame part (6Aa). An outer edge of a resin mold part (4) has an extension section (4e) extending in the second direction. The main frame part (6Aa) has, between a first power semiconductor chip (2a) and the main terminal part (6Ab) in the third direction, a first slit (5) or a first groove that extends over a third dimension in the second direction and has a fourth dimension that is less than the third dimension in the third direction.

Description

Power module and power conversion device

[0001] The present disclosure relates to a power module and a power conversion device, and more particularly to a power module including a lead frame and a power conversion device having the same.

[0002] Japanese Patent Laid-Open Publication No. 2009-111154 (Patent Document 1) discloses a transfer mold type power module. This power module includes a power semiconductor chip, an integrated circuit for controlling the power semiconductor chip, a plate-shaped lead frame having one main surface and another main surface, a heat sink, an insulating sheet, and a molded resin. The lead frame includes a first frame portion having a power semiconductor chip mounted on one main surface, a second frame portion having a control integrated circuit mounted on one main surface, a first lead terminal connected to the first frame portion, and a second lead terminal connected to the second frame portion. The heat sink is disposed such that one main surface faces the other main surface of the first frame portion. An insulating sheet is interposed between the first frame portion and the heat sink, electrically insulating them and thermally coupling them. The molded resin has a first side surface from which the first lead terminal protrudes and a second side surface from which the second lead terminal protrudes, and encapsulates the lead frame portion including the power semiconductor chip and the control integrated circuit.

[0003] Japanese Patent Laid-Open Publication No. 2002-314030 (Patent Document 2) discloses a semiconductor device having a lead frame and a resin. The lead frame has a die pad portion on which a semiconductor element is mounted and a substrate mounting portion on which a circuit board is mounted. The resin encapsulates the semiconductor element, the circuit board, the die pad portion, and the substrate mounting portion. The lead frame has an anchoring region between at least the die pad portion and the substrate mounting portion, which has a higher anchoring effect for the resin than the die pad portion and the substrate mounting portion. According to the publication's allegation, this configuration improves the adhesion of the resin to the lead frame, preventing cracks in the semiconductor element mounted on the lead frame and breakage of bonding wires.

[0004] JP 2009-111154 A JP 2002-314030 A

[0005] A transfer mold type power module has a power semiconductor chip, a lead frame, a resin molded portion, and a support portion. The lead frame has a first surface on which the power semiconductor chip is mounted and a second surface supported by the support portion. The lead frame also has main terminal portions that are terminal portions for the main current handled by the power module. The main terminal portions have a covered portion supported by the support portion and covered by the resin molded portion, and a protruding portion that protrudes from the resin molded portion.

[0006] A bus bar is connected to the protruding portion of the main terminal portion of a high-capacity power module. When the bus bar is connected, stress is applied from the bus bar to the main terminal portion. Even after this connection, stress may be applied from the bus bar to the main terminal portion due to external vibrations, etc. Here, the main terminal portion of a high-capacity power module has a large cross-sectional area to allow a large current flow. That is, the width and thickness dimensions perpendicular to the extension direction are large. Therefore, the main terminal portion has high rigidity and a large width. Because the main terminal portion has high rigidity, stress from the bus bar is likely to be applied to the entire main terminal portion. Furthermore, because the main terminal portion has a large width, peeling at the interface between the first surface of the main terminal portion and the resin molded portion or the supporting portion is likely to occur, especially near the center of the width.

[0007] First, the insulation reliability of the power module is reduced when the peeling of the resin molded portion from the main terminal portion of the lead frame progresses toward the power semiconductor chip. For example, insufficient sealing of the power semiconductor chip can cause moisture absorption near the power semiconductor chip, which can reduce the insulation reliability. Furthermore, bonding wires may be connected to the power semiconductor chip, and if the peeling progresses to the bonding wires, the wires may break, reducing the insulation reliability or causing an unintended short circuit.

[0008] Second, the heat dissipation characteristics of the power module deteriorate as the peeling of the support from the main terminal progresses toward the power semiconductor chip. For example, in a case where the support has a thin insulating sheet in contact with the lead frame and a metal module base, the peeling inhibits heat conduction from the power semiconductor chip to the module base via the insulating sheet.

[0009] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a power module and a power conversion device that can suppress deterioration in insulation reliability and heat dissipation characteristics.

[0010] A power module according to one aspect of the present disclosure is a power module including a lead frame. The power module includes at least one power semiconductor chip including a first power semiconductor chip, and a main frame portion that is a part of the lead frame and has a first surface on which the at least one power semiconductor chip is mounted and a second surface opposite the first surface in a first direction. The main frame portion has a first end portion having a first dimension along a second direction intersecting the first direction. The power module further includes a main terminal portion that is a part of the lead frame and directly adjacent to the main frame portion in a third direction intersecting the first and second directions. The main terminal portion has a second end portion connected to the first end portion of the main frame portion. Of the at least one power semiconductor chip, the first power semiconductor chip is closest to the main terminal portion. The power module further includes a support portion on which the main frame portion is mounted so as to face the second surface of the main frame portion, and a resin mold portion that encapsulates the main frame portion and the at least one power semiconductor chip and partially encapsulates the main terminal portion, and that has an outer edge in a plan view including the second direction and the third direction. The outer edge has an extending portion that extends along the second direction. The main terminal portion protrudes outside the resin mold portion from the extending portion of the outer edge of the resin mold portion. The main frame portion has a first slit or first groove between the first power semiconductor chip and the main terminal portion in the third direction, the first slit or first groove extending a third dimension along the second direction and having a fourth dimension in the third direction that is smaller than the third dimension.

[0011] A power module according to another aspect of the present disclosure is a power module including a lead frame, the power module including at least one power semiconductor chip including a first power semiconductor chip, and a main frame portion that is a part of the lead frame and has a first surface on which the at least one power semiconductor chip is mounted and a second surface opposite to the first surface in a first direction, the main frame portion having a first end portion with a first dimension along a second direction intersecting the first direction, the power module further including a main terminal portion that is a part of the lead frame and directly adjacent to the main frame portion in a third direction intersecting the first and second directions, the main terminal portion having a second end portion connected to the first end portion of the main frame portion, the second end portion having a second dimension along the second direction that is smaller than the first dimension, and the first power semiconductor chip of the at least one power semiconductor chip. and a resin molded portion that encapsulates the main frame portion and the at least one power semiconductor chip and partially encapsulates the main terminal portion and has an outer edge in a plan view including the second direction and the third direction, the outer edge having an extending portion that extends along the second direction, and the main terminal portion protrudes to the outside of the resin molded portion from the extending portion of the outer edge of the resin molded portion. The main frame portion has, between the first power semiconductor chip and the main terminal portion in the third direction, a through hole that extends a third dimension along the second direction and has a fourth dimension in the third direction that is smaller than the third dimension, or a plurality of through holes that are arranged along the second direction.

[0012] According to one aspect of the present disclosure, stress transmitted from the outside of the power module to the main frame portion via the main terminal portion is alleviated by the first slit or the first groove. This also alleviates stress applied to the main terminal portion. Therefore, first, peeling of the resin mold portion from the main terminal portion is suppressed, thereby suppressing a deterioration in the insulation reliability of the power module due to the peeling. Second, peeling of the support portion from the main terminal portion is suppressed, thereby suppressing a deterioration in the heat dissipation characteristics of the power module due to the peeling. From the above, it is possible to suppress a deterioration in the insulation reliability and heat dissipation characteristics of the power module.

[0013] According to another aspect of the present disclosure, stress transmitted from the outside of the power module to the main frame portion via the main terminal portion is alleviated by a through hole extending along the second direction or a plurality of through holes arranged along the second direction. This also alleviates stress applied to the main terminal portion. Therefore, first, peeling of the resin mold portion from the main terminal portion is suppressed, thereby suppressing a deterioration in the insulation reliability of the power module due to the peeling. Second, peeling of the support portion from the main terminal portion is suppressed, thereby suppressing a deterioration in the heat dissipation characteristics of the power module due to the peeling. From the above, it is possible to suppress a deterioration in the insulation reliability and heat dissipation characteristics of the power module.

[0014] FIG. 1 is a plan view schematically showing the configuration of a power module according to a first embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. FIG. 2 is a cross-sectional view schematically showing the configuration of the power module shown in FIG. 1, together with bus bars, taken along line II-II in FIG. 1. FIG. 3 is a top view schematically showing the configuration of the power module shown in FIG. 1. FIG. 4 is a symbolic diagram schematically showing the configuration of an insulated gate bipolar transistor as an example of the semiconductor chip shown in FIG. 1. FIG. 5 is a plan view schematically showing the configuration of a power module according to a modification of the first embodiment, viewed from the same perspective as FIG. 1. FIG. 6 is a plan view schematically showing the configuration of a power module according to a modification of the first embodiment, viewed from the same perspective as FIG. 1. FIG. 7 is a plan view schematically showing the configuration of a power module according to a modification of the first embodiment, viewed from the same perspective as FIG. 1. FIG. 8 is a plan view schematically showing the configuration of a power module according to a modification of the first embodiment, viewed from the same perspective as FIG. 3. FIG. 9 is a plan view schematically showing the configuration of a power module according to a modification of the first embodiment, viewed from the same perspective as FIG. 3. FIG. 10 is a plan view schematically showing the configuration of a power module according to a modification of the first embodiment, with the same field of view as FIG. 3 . FIG. 11 is a plan view schematically showing the configuration of a power module according to a modification of the first embodiment, with the same field of view as FIG. 3 . FIG. 12 is a front view schematically showing the internal configuration of a power module according to a second embodiment, together with bus bars. FIG. 13 is a front view schematically showing the configuration of a power module according to a modification of the second embodiment, together with bus bars, with the same field of view as FIG. 12 . FIG. 14 is a side view schematically showing the configuration of the power module shown in FIG. 13 . FIG. 15 is a cross-sectional view schematically showing the configuration of a power module according to a third embodiment, together with bus bars, bolts, and nuts. FIG. 16 is a partial plan view schematically explaining attachment of bus bars to the power module shown in FIG. 15 . FIG. 17 is a plan view schematically showing the configuration of a power module according to a fourth embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. FIG. 18 is a plan view schematically showing the configuration of a power module according to a modification of the fourth embodiment, with the same field of view as FIG. 17 .FIG. 19 is a plan view schematically showing the configuration of a power module according to a fifth embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. FIG. 20 is a plan view schematically showing the configuration of a power module according to a modification of the fifth embodiment, with the same field of view as FIG. 19 . FIG. 21 is a plan view schematically showing the configuration of a power module according to a sixth embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. FIG. 22 is a plan view schematically showing the configuration of a power module according to a seventh embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. FIG. 23 is a partial cross-sectional view schematically showing an example of the configuration of a main frame portion and a resin mold portion in the vicinity of a groove in the main frame portion in the power module shown in FIG. 22 . FIG. 24 is a partial cross-sectional view schematically showing another example of the configuration of a main frame portion and a resin mold portion in the vicinity of a groove in the main frame portion in the power module shown in FIG. 22 . FIG. 25 is a plan view schematically showing the configuration of a power module according to an eighth embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. FIG. 26 is a plan view schematically showing the configuration of a power module according to a ninth embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. FIG. 27 is a plan view schematically showing the configuration of a power module according to a modified example of the ninth embodiment, with the same field of view as FIG. 26. FIG. 28 is a plan view schematically showing the configuration of a power module according to a modified example of the ninth embodiment, with the same field of view as FIG. 26. FIG. 29 is a plan view schematically showing the configuration of a power module according to a modified example of the ninth embodiment, with the same field of view as FIG. 26. FIG. 30 is a plan view schematically showing the configuration of a power module according to a tenth embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. FIG. 31 is a plan view schematically showing the configuration of a power module according to an eleventh embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. FIG. 32 is a plan view schematically showing the configuration of a power module according to a twelfth embodiment, with some of the configuration omitted so that the interior of the configuration can be seen.FIG. 33 is a plan view schematically showing the configuration of a power module according to a thirteenth embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. FIG. 34 is a cross-sectional view schematically showing the configuration of the power module shown in FIG. 33, together with bus bars, taken along line XXXIV-XXXIV in FIG. 33. FIG. 35 is a plan view schematically showing the configuration of a power module according to a fourteenth embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. FIG. 36 is a plan view schematically showing the configuration of a power module according to a fifteenth embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. FIG. 37 is a plan view schematically showing the configuration of a power module according to a modification of the fifteenth embodiment, taken from the same perspective as FIG. 36. FIG. 38 is a plan view schematically showing the configuration of a power module according to a modification of the fifteenth embodiment, taken from the same perspective as FIG. 36. FIG. 39 is a plan view schematically showing the configuration of a power module according to a sixteenth embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. FIG. 40 is a cross-sectional view schematically showing the configuration of the power module shown in FIG. 39 together with bus bars, taken along line XL-XL in FIG. 39 . FIG. 41 is a partially enlarged view of FIG. 40 . FIG. 42 is a plan view schematically showing the configuration of a power module according to a modification of embodiment 16, from the same field of view as FIG. 41 . FIG. 43 is a plan view schematically showing the configuration of a power module according to a modification of embodiment 16, from the same field of view as FIGS. 41 and 42 . FIG. 44 is a plan view schematically showing the configuration of a power module according to a modification of embodiment 16, from the same field of view as FIG. 39 . FIG. 45 is a plan view schematically showing the configuration of a power module according to a modification of embodiment 16, from the same field of view as FIG. 39 . FIG. 46 is a plan view schematically showing the configuration of a power module according to a modification of embodiment 16, from the same field of view as FIG. 39 . FIG. 47 is a block diagram schematically showing the configuration of a power conversion system to which the power conversion device according to embodiment 17 is applied.

[0015] Hereinafter, embodiments will be described with reference to the drawings. In the following drawings, identical or corresponding parts are designated by the same reference numerals, and descriptions thereof will not be repeated. In this specification, alloys having metallic properties are considered to be metals. In addition, an XYZ Cartesian coordinate system is shown in some of the drawings to facilitate understanding of the directional relationships between the drawings.

[0016] <First Embodiment> Fig. 1 is a plan view that schematically shows the configuration of a power module 100 according to a first embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. Fig. 2 is a cross-sectional view that schematically shows the configuration of the power module 100 together with a bus bar 10, taken along line II-II in Fig. 1. Fig. 3 is a top view that schematically shows the configuration of the power module 100.

[0017] The power module 100 is a transfer mold type power module and includes a resin mold part 4 and at least one power semiconductor chip 2 sealed thereby. The at least one power semiconductor chip 2 includes a first power semiconductor chip 2a. In the example shown in Fig. 1, the at least one power semiconductor chip 2 also includes a second power semiconductor chip 2b, etc. In the following, a case where the at least one power semiconductor chip 2 is a plurality of power semiconductor chips 2 including a first power semiconductor chip 2a and a second power semiconductor chip 2b will be described in detail.

[0018] The power module 100 includes a lead frame group 6. The lead frame group 6 includes at least one lead frame 6A on which a power semiconductor chip 2 is mounted, and in the example shown in FIG. 1 , includes two lead frames 6A. Each lead frame 6A includes a main frame portion 6Aa and a main terminal portion 6Ab, as will be described in detail later. The lead frame 6A may be for the main current of the power module 100. For example, the lead frame 6A may be used as part of a power supply path from the power module 100 serving as an inverter device (power conversion device) to a load such as a motor. A bus bar 10 is connected to the lead frame 6A as another part of the power supply path. The bus bar 10 ( FIG. 3 ) is connected to the main terminal portion 6Ab ( FIG. 1 ) of the lead frame 6A on the upper surface of the lead frame 6A in FIG. 2 . As a variant, the connection may be made on the lower surface of the lead frame 6A.

[0019] The lead frame group 6 may also include a lead frame 6G on which no power semiconductor chip 2 is mounted. The lead frame group 6 may also include a lead frame 6S (FIG. 3 (not shown in FIGS. 1 and 2)) for transmitting a control signal for the power semiconductor chip 2.

[0020] The lead frame group 6 is made of a metal material, preferably copper, a copper alloy, aluminum, or an aluminum alloy, because of their high conductivity and workability. The same is true for the material of the bus bar 10.

[0021] The power module 100 includes a support portion SP. The support portion SP may have a module base 9 made of metal and an insulating sheet 8 that is disposed on the module base 9 and is thinner than the module base 9. The module base 9 is preferably made of a material having high thermal conductivity, and more specifically, is preferably made of metal. The metal is, for example, aluminum, an aluminum alloy, copper, or a copper alloy. The inclusion of copper makes it easier to ensure high thermal conductivity. The module base 9 may be formed using machining, die-casting, forging, extrusion, or the like.

[0022] The main frame portion 6Aa has a first surface F1 on which at least one power semiconductor chip 2 is mounted and a second surface F2 opposite the first surface F1 in the Z direction (first direction). The main frame portion 6Aa has a first end portion ED1 having a first dimension along a second direction intersecting the first direction (Z direction). The second direction is orthogonal to the Z direction (first direction) if manufacturing errors are ignored. Therefore, the following description will be given assuming that the second direction is the Y direction. In this case, the main frame portion 6Aa has a first end portion ED1 having a first dimension along the Y direction.

[0023] The main terminal portion 6Ab is directly adjacent to the main frame portion 6Aa in a third direction intersecting the first direction (Z direction) and the second direction (Y direction). The third direction is perpendicular to the Z direction (first direction) and the Y direction (second direction) if manufacturing errors are ignored. Therefore, the following description will be given assuming that the third direction is the X direction. In this case, the main terminal portion 6Ab is directly adjacent to the main frame portion 6Aa in the X direction. The main terminal portion 6Ab has a second end portion ED2 connected to a first end portion ED1 of the main frame portion 6Aa. The second end portion ED2 has a second dimension along the Y direction that is smaller than the first dimension of the first end portion ED1. Among the multiple power semiconductor chips 2, the first power semiconductor chip 2a is closest to the main terminal portion 6Ab. In the first embodiment, the main terminal portions 6Ab are arranged at the right and left ends of each main frame portion 6Aa in Fig. 1, and therefore two of the power semiconductor chips 2 correspond to the first power semiconductor chip 2a. In a modified example in which only a single power semiconductor chip 2 is mounted, this power semiconductor chip is regarded as the first power semiconductor chip 2a.

[0024] The main frame portion 6Aa is mounted on the support portion SP, so that the support portion SP faces the second surface F2 of the main frame portion 6Aa.

[0025] The resin molded portion 4 seals the main frame portion 6Aa and the power semiconductor chip 2. The resin molded portion 4 also partially seals the main terminal portion 6Ab of the lead frame 6A. Similarly, the resin molded portion 4 partially seals each of the lead frames 6G and 6S. This allows the resin molded portion 4 to fix the lead frame group 6 to each other. Meanwhile, the lower surface of the support portion SP opposite to the support surface (upper surface in FIG. 2 ) may be exposed from the resin molded portion 4 as shown in FIG. 2 . This lower surface is the surface of the module base 9 opposite to the surface facing the insulating sheet 8.

[0026] The resin molded portion 4 has an outer edge (indicated by the two-dot chain line in FIG. 1 ) in a plan view including the Y direction (second direction) and the X direction (third direction), in other words, in a plan view corresponding to the XY plane. The outer edge may be the outer edge of the resin molded portion 4 on an imaginary plane including the first surface F1 of the lead frame 6A. The outer edge has an extending portion 4e extending along the Y direction. The main terminal portion 6Ab protrudes from the extending portion 4e of the outer edge of the resin molded portion 4 to the outside of the resin molded portion 4.

[0027] The resin molded portion 4 is made of a material containing resin and is formed by molding. The molding is performed so that each of the lead frame group 6 is partially exposed from the resin molded portion 4. After molding, if necessary, processing may be performed on the portion of the lead frame group 6 outside the resin molded portion 4 to impart a desired shape. The zigzag shape of the main terminal portion 6Ab ( FIG. 12 ) in a plan view including the Z direction (see FIG. 12 ) in the second embodiment described below may be formed by this processing. In contrast, in the first embodiment, the main terminal portion 6Ab extends only in the horizontal direction including the Y direction and the X direction. In other words, the main terminal portion 6Ab has a flat plate shape parallel to the horizontal direction.

[0028] The main frame portion 6Aa has a first slit 5 between the first power semiconductor chip 2a and the main terminal portion 6Ab in the X direction. In other words, the first slit 5 has an X coordinate between the X coordinate of the first power semiconductor chip 2a and the X coordinate of the main terminal portion 6Ab. The range in the Y direction in which the first power semiconductor chip 2a is disposed and the range in the Y direction in which the main terminal portion 6Ab is disposed may at least partially overlap, and this overlapping range is referred to as an overlapping range. This overlapping range and the range in the Y direction in which the first slit 5 is disposed may at least partially overlap. In other words, if a Y coordinate range commonly included in the Y coordinate range in which the first power semiconductor chip 2a is disposed and the Y coordinate range in which the main terminal portion 6Ab is disposed is referred to as a common Y coordinate range, this common Y coordinate range and the Y coordinate range in which the first slit 5 is disposed may at least partially overlap.

[0029] The first slit 5 extends a third dimension (length dimension) along the Y direction and has a fourth dimension (width dimension) in the X direction that is smaller than the third dimension (length dimension). In other words, the first slit 5 has a length (dimension in the Y direction) that is greater than its width (dimension in the X direction). The first slit 5 has, in the Y direction, one end that reaches the outer edge of the lead frame 6A and the other end that is distant from the outer edge of the lead frame 6A. Therefore, the first slit 5 does not completely divide the lead frame 6A.

[0030] The first slits 5 of the main frame portion 6Aa may be disposed on the support portions SP. Specifically, the first slits 5 of the main frame portion 6Aa may be disposed on the insulating sheet 8.

[0031] The power module 100 may have wires 3 as additional electrical wiring other than the lead frame group 6 within the resin molded portion 4. The wires 3 are made of, for example, aluminum or copper. As this additional electrical wiring, a metal plate joined with a joining material such as solder may be used instead of or together with the wires 3. In the example shown in FIG. 1, wires 3 are provided to connect the power semiconductor chip 2 mounted on the lead frame 6A in the lower row in the figure to the main frame portion 6Aa of the lead frame 6A in the middle row in the figure. Also, wires 3 are provided to connect the power semiconductor chip 2 mounted on the lead frame 6A in the middle row in the figure to the lead frame 6G. The same applies to additional electrical wiring for connecting the lead frame 6S (FIG. 3 (not shown in FIGS. 1 and 2)).

[0032] FIG. 4 is a symbolic diagram schematically illustrating the configuration of an insulated gate bipolar transistor (IGBT) as an example of a semiconductor chip, i.e., the power semiconductor chip 2 shown in FIG. 1 . The IGBT has a collector electrode 2C, an emitter electrode 2E, and a gate electrode 2G. In the configuration shown in FIG. 1 , the collector electrode 2C is bonded to the main frame portion 6Aa of the lead frame 6A by a conductive member 7 ( FIG. 2 ). The conductive member 7 may be, for example, a solder layer or a conductive adhesive layer. Instead of bonding using these layers, metal particle sintering bonding, liquid phase diffusion bonding, or solid-state bonding may be used. The emitter electrode 2E is electrically connected by a wire 3 to a lead frame different from the lead frame 6A on which the power semiconductor chip 2 having the emitter electrode 2E is mounted. The gate electrode 2G is bonded to the lead frame 6S ( FIG. 3 ) within the resin mold portion 4. The power semiconductor chip 2 may be a transistor other than an IGBT, such as a metal-insulator-semiconductor field-effect transistor (MISFET). The power semiconductor chip 2 may also be a diode. The power semiconductor chips 2 may also include transistors and freewheeling diodes connected in parallel to one another. The semiconductor material of the power semiconductor chips may be silicon or a wide bandgap semiconductor. Wide bandgap semiconductors are typically silicon carbide or gallium nitride.

[0033] According to the first embodiment, when stress is transmitted from outside the power module 100 to the main frame portion 6Aa via the main terminal portion 6Ab due to a load applied when the bus bar 10 is connected or external vibrations, the stress is alleviated by the first slits 5. This also alleviates the stress applied to the main terminal portion 6Ab. Therefore, first, peeling of the resin mold portion 4 from the main terminal portion 6Ab is suppressed. Specifically, the occurrence of such peeling is suppressed, and even if such peeling occurs, it is suppressed from spreading along the X direction (third direction) toward the first power semiconductor chip 2a. Therefore, a deterioration in the insulation reliability of the power module 100 due to such peeling is suppressed. Second, peeling of the support portion SP from the main terminal portion 6Ab is suppressed. Specifically, the occurrence of such peeling is suppressed, and even if such peeling occurs, it is suppressed from spreading. Therefore, a deterioration in the heat dissipation characteristics of the power module 100 due to such peeling is suppressed. As a result, the deterioration of the insulation reliability and heat dissipation characteristics of the power module 100 can be suppressed.

[0034] In addition to the stresses described above, the first slits 5 can also relieve thermal stresses that occur during processes such as die bonding and transfer molding. This reduces warping of the lead frame 6A due to thermal stress. If warping were excessive, molding resin could seep under the lead frame 6A during the transfer molding process, potentially deteriorating the insulation or heat dissipation characteristics of the power module. Furthermore, when a workpiece is transported between the die bonding and transfer molding processes, contact between the lead frame 6A and the wires 3 is likely to occur due to vibrations or impacts during transport, which could adversely affect the insulation characteristics of the power module 100. Furthermore, there is a risk of transport abnormalities during transport, such as failure to properly store the workpiece in the magazine, or a reduction in the number of workpieces that can be stored in the magazine. These issues could lead to a decrease in the productivity of the power module 100. In particular, power modules for large capacity bands often have many power semiconductor chips 2 mounted thereon, and each power semiconductor chip 2 tends to be large in size, in which case warpage due to thermal stress is likely to become a problem. By reducing the warpage of the lead frame 6A according to the first embodiment, it is possible to suppress the deterioration of the insulation reliability and heat dissipation characteristics of the power module 100 caused by the warpage. It is also possible to suppress the decrease in productivity.

[0035] When a rectangular first slit 5 is formed in the rectangular main frame portion 6Aa indicated by the dotted line in FIG. 1 , an example of numerical analysis was conducted under the conditions that the width of the main frame portion 6Aa (i.e., the dimension of the main frame portion 6Aa in the Y direction) is 100%, and the length of the first slit 5 extending along the Y direction is 30%, 50%, and 70%, respectively. Therefore, it is believed that a more reliable effect can be achieved when the length of the first slit 5 is 30% or more of the width of the main frame portion 6Aa. On the other hand, if the length of the first slit 5 is excessively long, current concentration becomes significant due to the current flowing through the main frame portion 6Aa having to bypass the first slit 5. As a result, there is a concern of localized temperature increases in the main frame portion 6Aa. To avoid this, it is preferable that the length of the first slit 5 be 70% or less of the width of the main frame portion 6Aa. On the other hand, from the viewpoint of productivity, it is preferable that the width (dimension in the X direction) of the first slit 5 is equal to or greater than the thickness (dimension in the Z direction) of the main frame portion 6Aa.

[0036] Furthermore, in the first embodiment, the main terminals 6Ab extend only in the horizontal direction. This eliminates the need for a process to process the main terminals 6Ab so that they extend in directions other than the horizontal direction. This improves the productivity of the power module 100.

[0037] <Modifications of First Embodiment> In the power module 100 described above, a single first slit 5 is formed in each of the left and right ends of each main frame portion 6Aa in FIG. 1 , and each first slit 5 extends from a common side of the main frame portion 6Aa. Specifically, in the lower main frame portion 6Aa in FIG. 1 , each first slit 5 extends from the lower side of the main frame portion 6Aa, and in the upper main frame portion 6Aa in FIG. 1 , each first slit 5 extends from the upper side of the main frame portion 6Aa. However, the arrangement of the first slits 5 is not limited to this arrangement. Some modifications from this perspective are described below.

[0038] Fig. 5 is a plan view schematically showing the configuration of a power module 101 according to a modification of the first embodiment, in the same field of view as Fig. 1. In the power module 101, for each main frame portion 6Aa, the first slits 5 extend from different sides of the main frame portion 6Aa in Fig. 5. Specifically, in Fig. 5, the first slit 5 on the left side extends from the lower side, and the first slit 5 on the right side extends from the upper side.

[0039] FIG. 6 is a plan view schematically illustrating the configuration of a power module 102 according to a modification of the first embodiment, in the same field of view as FIG. 1 . In the power module 102, a pair of first slits 5, ie, slits 5a and 5b, are formed at the left and right ends of each main frame portion 6Aa in FIG. 6 , and these slits extend from different sides of the main frame portion 6Aa. The positions of the slits 5a and 5b in the X direction are roughly the same. In other words, the slits 5a and 5b are located at roughly the same X coordinate. In other words, the slits 5a and 5b extend along a common imaginary straight line along the Y direction (second direction).

[0040] 7 is a plan view schematically showing the configuration of a power module 103 according to a modification of the first embodiment, in the same field of view as in FIG. 1. In the power module 103 (FIG. 7), the positions of the slits 5a and 5b in the X direction are different from those in the power module 102 (FIG. 6). In the Y direction, the range of the slits 5a and the range of the slits 5b may partially overlap.

[0041] Referring again to FIG. 3 , the shape of the resin molded portion 4 is approximately rectangular in a plan view corresponding to the XY plane. In the power module 100 of the first embodiment described above, the exposed lead frames 6A and 6G are arranged on two sides of the rectangle, and the exposed lead frame 6S is arranged on the other two sides of the rectangle. However, the arrangement of the lead frame group 6 is not limited to this arrangement. Some modifications from this perspective are described below.

[0042] Fig. 8 is a plan view schematically showing the configuration of a power module 104 according to a modification of the first embodiment, in the same field of view as Fig. 3. In the power module 104, exposed lead frames 6A and 6G are arranged on one side of the rectangle, and exposed lead frames 6S are arranged on the other two sides of the rectangle, the two sides being opposite to each other.

[0043] Fig. 9 is a plan view schematically showing the configuration of a power module 105 according to a modification of the first embodiment, in the same field of view as Fig. 3. In the power module 105, exposed lead frames 6A, 6G, and 6S are arranged on each of two opposite sides.

[0044] 3 again, in the power module 100 of the first embodiment described above, in a plan view corresponding to the XY plane, the structure of the portion of the lead frame 6A that protrudes from the resin molded portion 4, in other words, the protruding structure, simply extends along the X direction. However, a more complicated protruding structure may also be used, and several modified examples from this perspective will be described below.

[0045] 10 and 11 are plan views each schematically illustrating the configuration of a power module 106 and a power module 107 according to a modification of the first embodiment, in the same field of view as FIG. 3 . The protruding structure of the power module 106 ( FIG. 10 ) is L-shaped. The protruding structure of the power module 107 ( FIG. 11 ) is U-shaped. By providing the main terminal portion 6Ab (see FIG. 5 ) with a curved protruding structure (rather than simply extending along the X direction), stress applied to the interface between the main terminal portion 6Ab and the resin molded portion 4 when the bus bar 10 (see FIG. 3 ) is joined to the main terminal portion 6Ab can be reduced. Furthermore, stress applied to the interface due to vibrations caused by some reason during use of the power module can also be reduced. This improves the vibration resistance of the power module.

[0046] Second Embodiment FIG. 12 is a front view schematically illustrating the internal configuration of a power module 110 according to a second embodiment, together with a bus bar 10. The lead frame 6S ( FIG. 3 ) is not shown. Unlike the main terminals 6Ab of the lead frame 6A of the power module 100 (see FIGS. 1 and 2 ), the main terminals 6Ab of the power module 110 have portions extending in directions different from the horizontal direction, including the Y and X directions. This provides a bend in the main terminals 6Ab. Specifically, the main terminals 6Ab of the power module 110 have a first portion 6Ab1, a second portion 6Ab2, and a third portion 6Ab3. The first portion 6Ab1 extends from a second end ED2 ( FIG. 1 ) of the main terminal 6Ab in the horizontal direction, including the Y and X directions. The second portion 6Ab2 extends from the first portion 6Ab1 in a direction intersecting the horizontal direction, specifically the Z direction. The third portion 6Ab3 extends horizontally from the second portion 6Ab2. Although the bus bar 10 is joined to the upper surface of the third portion 6Ab3 in FIG. 12, it may be joined to the lower surface of the third portion 6Ab3 as a modified example.

[0047] Note that, other than the above, the configuration is substantially the same as that of the above-described first embodiment or its modified example, and therefore the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0048] The main terminal portion 6Ab has the above-described bent structure, which reduces stress applied to the interface between the main terminal portion 6Ab and the resin molded portion 4 when the bus bar 10 (see FIG. 3) is joined to the main terminal portion 6Ab. It also reduces stress applied to the interface due to vibrations caused by some reason during use of the power module. This improves the vibration resistance of the power module. Furthermore, the height position (position in the Z direction) of the third portion 6Ab3 to which the bus bar 10 is connected can be adjusted depending on the extension length of the second portion 6Ab2. This increases the degree of freedom in the design of a unit including a power module.

[0049] Fig. 13 is a front view schematically showing the configuration of a power module 111 according to a modification of the second embodiment, together with the bus bar 10, in the same field of view as Fig. 12. Note that the lead frame 6S is not shown. Fig. 14 is a side view schematically showing the configuration of the power module 111. In a plan view corresponding to the XY plane, the main terminal portion 6Ab of the power module 111 has an L-shape similar to that of the power module 106 (Fig. 10) described above.

[0050] Third Preferred Embodiment In a third preferred embodiment, a method for connecting the bus bar 10 (see FIGS. 2 and 3) to the main terminal portion 6Ab (see FIG. 1) of the lead frame 6A will be described in detail.

[0051] FIG. 15 is a cross-sectional view schematically illustrating the configuration of a power module 120 according to the third embodiment, together with a bus bar 10, a bolt 12, and a nut 13. The lead frame 6S is not shown. FIG. 16 is a partial plan view schematically illustrating the attachment of a bus bar 10 to the power module 120 shown in FIG. 15. The portion of the main terminal 6Ab of the power module 120 that protrudes from the resin molded portion 4 has a hole 14a. The bus bar 10 to be connected to the power module 120 has a hole 14b. To connect the bus bar 10, a bolt 12 and a nut 13 are used as fastening members. Specifically, the bolt 12 is inserted so as to pass through the hole 14a and the hole 14b, and is fixed by the nut 13. Although the bus bar 10 is connected to the upper surface of the lead frame 6A in FIG. 15, the bus bar 10 may also be connected to the lower surface of the lead frame 6A.

[0052] 15, the head of the bolt 12 is arranged on the upper side and the nut 13 is arranged on the lower side, which makes it easier to fasten the bolt 12 and the nut 13. However, as a modified example, the relative positions of the bolt 12 and the nut 13 may be reversed.

[0053] The method for connecting the bus bars 10 is not limited to the above-described method. Other connection methods may be used instead of or in combination with the above-described connection methods. For example, connection using a joining material such as solder, connection by welding, or connection by crimping are possible.

[0054] The configuration other than the above is substantially the same as that of the first embodiment or its modification, and therefore the same or corresponding elements are denoted by the same reference numerals, and description thereof will not be repeated. The features of the third embodiment may also be applied to the second embodiment or its modification, in which case the hole 14a may be provided in the third portion 6Ab3 of the main terminal portion 6Ab (see FIGS. 12 to 14).

[0055] 17 is a plan view schematically illustrating the configuration of a power module 130 according to the present embodiment 4, with some of the configuration omitted so that the interior of the configuration can be seen. The main frame portion 6Aa of the power module 130 has through holes 15 instead of the first slits 5 (FIG. 1: embodiment 1).

[0056] The arrangement and shape of the through holes 15 are almost the same as the arrangement and shape of the first slits 5. However, unlike the edges of the first slits 5, the edges of the through holes 15 are spaced apart from the outer edges of the lead frame 6A.

[0057] The width dimension of the through hole 15 may be larger than the thickness of the lead frame 6A. In other words, the dimension of the through hole 15 in the X direction (fourth dimension) may be larger than the dimension of the lead frame 6A in the Z direction.

[0058] Note that the configuration other than that described above is substantially the same as that of the above-described first to third embodiments or their modifications, and therefore the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0059] Fig. 18 is a plan view schematically showing the configuration of a power module 131 according to a modification of the fourth embodiment, in the same field of view as Fig. 17. The main frame portion 6Aa of the power module 131 has a plurality of through holes 15 arranged along the Y direction (second direction).

[0060] Fifth Embodiment Fig. 19 is a plan view schematically illustrating the configuration of a power module 140 according to a fifth embodiment, with some components omitted so that the interior of the configuration can be seen. The main frame portion 6Aa of the power module 140 has a plurality of through holes 16 between the first power semiconductor chip 2a and the main terminal portion 6Ab in the X direction (third direction), instead of the through hole 15 (Fig. 17: fourth embodiment). The plurality of through holes 16 are arranged along the Y direction (second direction). The shape of each through hole 16 in a plan view corresponding to the XY plane may be a shape that encompasses a circle having a diameter greater than the thickness (dimension in the Z direction) of the lead frame 6A.

[0061] Although each of the through holes 15 in the modified example of the fourth embodiment ( FIG. 18 ) described above has a length (dimension in the Y direction) that is greater than its width (dimension in the X direction), each of the through holes 16 in the fifth embodiment does not necessarily have to have such a dimensional relationship. For example, in the example shown in FIG. 19 , the shape of the through hole 16 is a square having a pair of sides along the X direction and a pair of sides along the Y direction. Alternatively, a rectangle in which the side along the X direction is longer than the side along the Y direction may be used. Furthermore, the shape of the through hole 16 in the modified power module 141 ( FIG. 20 ) is circular. Thus, the shape of the through hole 16 is not particularly limited.

[0062] Note that, other than the above, the configuration is substantially the same as that of the above-described fourth embodiment or its modified example, and therefore the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0063] Sixth Embodiment FIG. 21 is a plan view schematically illustrating a configuration of a power module 150 according to a sixth embodiment, with some components omitted so that the interior of the configuration can be seen. The power module 150 has both the first slits 5 (see the first embodiment) and the through holes 15 (see the fourth embodiment). The through holes 15 and the first slits 5 may extend along a common imaginary straight line along the Y direction (second direction). As a modified example, a plurality of through holes 16 (see the fifth embodiment) may be used instead of the through holes 15. Furthermore, in the sixth embodiment, a single through hole 16 may be used instead of the plurality of through holes 16. As described above, the first slits 5 extend along an imaginary straight line along the Y direction (second direction), and at least one through hole 16 may be disposed on this imaginary line. Note that the configuration other than the above is substantially the same as the configurations of the first to third embodiments or their modified examples. Therefore, the same or corresponding elements are designated by the same reference numerals, and description thereof will not be repeated.

[0064] Seventh Embodiment Fig. 22 is a plan view schematically illustrating the configuration of a power module 160 according to a seventh embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. Figs. 23 and 24 are partial cross-sectional views schematically illustrating two examples of the configuration of the main frame portion 6Aa and the resin molded portion 4 in the vicinity of the first groove 17 shown in Fig. 22. The cross-sectional shape of the first groove 17 is not particularly limited; for example, it is V-shaped in Fig. 23, and is rectangular with a flat bottom in Fig. 24.

[0065] The main frame portion 6Aa of the power module 160 has first grooves 17 instead of the first slits 5 (FIG. 1: embodiment 1). The arrangement and shape of the first grooves 17 are substantially the same as the arrangement and shape of the first slits 5. However, both ends of the first grooves 17 (upper and lower ends in FIG. 22) may reach the outer edges of the lead frame 6A as shown in FIG. 22. As a first modification, one end of the first groove 17 may reach the outer edge of the lead frame 6A, and the other end may be spaced apart from the outer edge of the lead frame 6A. As a second modification, both ends of the first grooves 17 may be spaced apart from the outer edges of the lead frame 6A.

[0066] Note that the configuration other than the above is substantially the same as that of the first to third embodiments or their variations. Therefore, the same or corresponding elements are denoted by the same reference numerals, and their description will not be repeated. According to the seventh embodiment, stress transmitted from the outside of the power module 160 to the main frame portion 6Aa via the main terminal portion 6Ab is alleviated by the first groove 17. This achieves substantially the same effect as the first to third embodiments. Furthermore, the formation of the first groove 17 does not create a defect in the shape of the lead frame 6A in a planar view corresponding to the XY plane. Therefore, current concentration caused by the current flowing through the main frame portion 6Aa having to bypass the defect in the planar view can be avoided.

[0067] Eighth Embodiment Fig. 25 is a plan view schematically illustrating the configuration of a power module 170 according to the eighth embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. The main frame portion 6Aa of the power module 170 has both a first groove 17 (Fig. 22: Seventh Embodiment) and at least one through hole 16 (see, for example, Fig. 20). The at least one through hole 16 may be disposed on the first groove 17. As shown in Fig. 25, when the at least one through hole 16 is a plurality of through holes 16, the plurality of through holes 16 may be arranged as described in the fifth embodiment.

[0068] Note that, other than the above, the configuration is almost the same as that of the seventh embodiment described above, and therefore the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0069] Ninth Embodiment Figure 26 is a plan view schematically illustrating the configuration of a power module 200 according to the ninth embodiment, with some components omitted so that the interior of the configuration can be seen. The main frame portion 6Aa of the lead frame 6A of the power module 200 has a second slit 5M between the first power semiconductor chip 2a and the second power semiconductor chip 2b in the X direction (third direction). The second slit 5M extends a fifth dimension (length dimension) along the Y direction (second direction) and has a sixth dimension (width dimension) in the X direction (third direction) that is smaller than the fifth dimension (length dimension). Like the first slit 5, the second slit 5M has one end reaching the outer edge of the lead frame 6A in the Y direction (second direction) and the other end away from the outer edge of the lead frame 6A. Therefore, like the first slit 5, the second slit 5M does not completely divide the lead frame 6A. Note that, other than the above, the configuration is substantially the same as that of the above-mentioned first to eighth embodiments or their modifications, and therefore the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0070] According to the ninth embodiment, the second slits 5M can relieve stress applied to the main frame portion 6Aa in the region between the first power semiconductor chip 2a and the second power semiconductor chip 2b. This prevents the lead frame 6A from peeling in this region. Furthermore, warping of the main frame portion 6Aa due to thermal stress can also be prevented.

[0071] In the power module 200 ( FIG. 26 ) described above, for each main frame portion 6Aa, multiple slits, including the first slit 5 and the second slit 5M, extend from a common side of the main frame portion 6Aa. Specifically, in the lower main frame portion 6Aa in FIG. 26 , each slit extends from the lower side of the main frame portion 6Aa, and in the upper main frame portion 6Aa in FIG. 26 , each slit extends from the upper side of the main frame portion 6Aa. However, the arrangement of the slits is not limited to this. For example, in a modified power module 201 ( FIG. 27 ), for each main frame portion 6Aa, adjacent slits in the X direction extend from different sides of the main frame portion 6Aa.

[0072] In the power module 200 (FIG. 26), the second slits 5M are provided in each of the multiple regions between the multiple power semiconductor chips 2 in the X direction, but it is not necessary to provide the second slits 5M in each of the multiple regions. For example, in the modified power module 202 (FIG. 28) and power module 203 (FIG. 29), two second power semiconductor chips 2b are arranged next to the first power semiconductor chip 2a on the left side in the figure, but no second slits 5M are provided in the region between the first power semiconductor chip 2a on the left side and the second power semiconductor chip 2b, of the two second power semiconductor chips 2b, that is closer to the first power semiconductor chip 2a on the left side.

[0073] 30 is a plan view schematically illustrating the configuration of a power module 210 according to a tenth embodiment, with some components omitted so that the interior of the configuration can be seen. The main frame portion 6Aa of the power module 210 has, in addition to the second slits 5M (see the ninth embodiment), through holes 15M between the first power semiconductor chip 2a and the second power semiconductor chip 2b in the X direction (third direction). The through holes 15M are arranged away from the second slits 5M.

[0074] Like the through hole 15, the through hole 15M may extend with a third dimension (length dimension) along the Y direction. In this case, the through hole 15M may have a fourth dimension (width dimension) in the X direction that is smaller than the third dimension (length dimension). In other words, the through hole 15M may have a length (dimension in the Y direction) that is larger than its width (dimension in the X direction). The through hole 15M and the second slit 5M may extend along a common imaginary straight line along the Y direction (second direction). The shape of the through hole 15M in a plan view corresponding to the XY plane may be a shape that encompasses a circle with a diameter larger than the thickness (dimension in the Z direction) of the lead frame 6A.

[0075] As a modified example, instead of each through hole 15M in Fig. 30, a plurality of through holes 15M may be provided. The plurality of through holes 15M may be arranged along the Y direction (second direction). The plurality of through holes 15M and the second slits 5M may extend along a common imaginary straight line along the Y direction (second direction).

[0076] Note that the configuration other than that described above is substantially the same as that of the above-mentioned embodiment 9 or its modified example, and therefore the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0077] Eleventh Embodiment FIG. 31 is a plan view schematically illustrating the configuration of a power module 220 according to the eleventh embodiment, with some components omitted so that the interior of the configuration can be seen. The main frame portion 6Aa of the power module 220 has a first groove 17 (FIG. 22: Embodiment 7) and a second groove 17M instead of the first slit 5 and the second slit 5M (FIG. 26: Embodiment 9). The arrangement and shape of the second groove 17M are substantially the same as those of the second slit 5M. However, both ends of the second groove 17M (upper and lower ends in FIG. 31) may reach the outer edge of the lead frame 6A as shown in FIG. 31. As a first modification, one end of the second groove 17M may reach the outer edge of the lead frame 6A, and the other end may be spaced apart from the outer edge of the lead frame 6A. As a second modification, both ends of the second groove 17M may be spaced apart from the outer edge of the lead frame 6A.

[0078] Note that, other than the above, the configuration is substantially the same as that of the above-mentioned first to eighth embodiments or their modifications, and therefore the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0079] According to the eleventh embodiment, the second groove 17M can relieve stress applied to the main frame portion 6Aa in the region between the first power semiconductor chip 2a and the second power semiconductor chip 2b. This prevents the lead frame 6A from peeling in this region. Furthermore, warping of the main frame portion 6Aa due to thermal stress can also be prevented.

[0080] Twelfth Embodiment FIG. 32 is a plan view schematically illustrating the configuration of a power module 230 according to a twelfth embodiment, with some components omitted so that the interior of the configuration can be seen. The main frame portion 6Aa of the power module 230 has, in addition to the second groove 17M (see the ninth embodiment) described above, at least one through hole 16M between the first power semiconductor chip 2a and the second power semiconductor chip 2b in the X direction (third direction). The at least one through hole 16M may be disposed on the second groove 17M. The at least one through hole 16M may be a plurality of through holes 16M. The plurality of through holes 16M may be arranged along the Y direction (second direction). The plurality of through holes 16M and the second groove 17M may extend along a common imaginary straight line along the Y direction (second direction). The at least one through hole 16M may extend a third dimension (length dimension) along the Y direction, similar to the through hole 15. In this case, the through hole 16M may have a fourth dimension (width dimension) in the X direction that is smaller than the third dimension (length dimension). In other words, the through hole 16M may have a length (dimension in the Y direction) that is larger than its width (dimension in the X direction). The shape of the through hole 16M in a plan view corresponding to the XY plane may be a shape that encompasses a circle with a diameter larger than the thickness of the lead frame 6A (dimension in the Z direction). Note that the configuration other than the above is substantially the same as the configuration of the eleventh embodiment described above, and therefore the same or corresponding elements are designated by the same reference numerals, and description thereof will not be repeated.

[0081] <Thirteenth Embodiment> Fig. 33 is a plan view schematically showing the configuration of a power module 300 according to a thirteenth embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. Fig. 34 is a cross-sectional view schematically showing the configuration of the power module 300 shown in Fig. 33 together with the bus bar 10, taken along line XXXIV-XXXIV in Fig. 33.

[0082] The power module 300 includes the configuration of the power module 100 (FIG. 1: embodiment 1) and also includes wires 30 (wiring members). The material of the wires 30 may be any of the materials exemplified as the material of the wires 3 in the above-described embodiment 1.

[0083] The wire 30 is joined to a first position (the left end position of the wire 30 in FIGS. 33 and 34 ) and a second position (the right end position of the wire 30 in FIGS. 33 and 34 ) on the first surface F1 of the main frame portion 6Aa so as to extend above the first slit 5 of the main frame portion 6Aa (see FIG. 34 ). The first and second positions are separated from each other by the first slit 5 in the X direction (third direction). The wire 30 does not extend along a single straight line between the first and second positions in the XYZ space. Specifically, although the wire 30 appears to extend along a single straight line in the XY plane ( FIG. 33 ), it extends along a curved line in the ZX plane.

[0084] According to the thirteenth embodiment, the wire 30 provides a current path between the first position and the second position not only by bypassing the first slit 5 but also by passing through the wire 30. This makes it possible to prevent a temperature rise due to local current concentration.

[0085] As a modified example, the wire 30 may be provided so as to exceed the through hole 15, the through hole 16, the first groove 17, the second slit 5M, the through hole 15M, the through hole 16M, or the second groove 17M. A plurality of features among the features of these modified examples may be applied.

[0086] In addition, other than the above, the configuration of this embodiment 13 or its variant is almost the same as the configuration of the above-mentioned embodiments 1 to 12 or their variants, so the same symbols are used for the same or corresponding elements and their descriptions will not be repeated.

[0087] 35 is a plan view schematically showing the configuration of a power module 400 according to this embodiment 14, with some of the configuration omitted so that the interior of the configuration can be seen. While the lead frame 6A of the power module 100 (FIG. 1: embodiment 1) has a main terminal portion 6Ab at each of both ends in the X direction, the lead frame 6A of the power module 400 according to this embodiment 14 has a main terminal portion 6Ab at only one of both ends in the X direction.

[0088] Note that the configuration other than that described above is substantially the same as that of the above-mentioned embodiments 1 to 13 or their modifications, and therefore the same or corresponding elements are given the same reference numerals and their description will not be repeated.

[0089] 36 is a plan view schematically illustrating a configuration of a power module 500 according to a fifteenth embodiment, with some components omitted so that the interior of the configuration can be seen. While the second end ED2 of the main terminal portion 6Ab of the power module 100 ( FIG. 1 : first embodiment) described above has a second dimension along the Y direction that is smaller than the first dimension of the first end ED1 of the main frame portion 6Aa, the second end ED2 of the main terminal portion 6Ab of a power module 500 ( FIG. 36 ) according to the fifteenth embodiment has a second dimension along the Y direction that is the same as the first dimension of the first end ED1 of the main frame portion 6Aa. The remaining configuration of the fifteenth embodiment is substantially the same as the configuration of the first embodiment. Therefore, the same or corresponding elements are designated by the same reference numerals, and description thereof will not be repeated.

[0090] Fig. 37 is a plan view schematically showing the configuration of a power module 501 according to a modification of the fifteenth embodiment, in the same field of view as Fig. 36. The second end ED2 of the main terminal portion 6Ab of the power module 501 (Fig. 37) in this modification has a second dimension along the Y direction that is larger than the first dimension of the first end ED1 of the main frame portion 6Aa.

[0091] Fig. 38 is a plan view schematically showing the configuration of a power module 502 according to a modification of the fifteenth embodiment, in the same field of view as Fig. 36. The second end ED2 of the main terminal portion 6Ab of the power module 502 (Fig. 38) in this modification has a second dimension along the Y direction that is larger than the first dimension of the first end ED1 of the main frame portion 6Aa. In this modification, the main terminal portion 6Ab also has multiple portions that protrude from the extending portion 4e of the outer edge of the resin molded portion 4 to the outside of the resin molded portion 4. These portions are separated from each other outside the resin molded portion 4.

[0092] The features regarding the dimensions of the main frame portion 6Aa and the main terminal portion 6Ab described in the fifteenth embodiment or its modifications may be applied to the other embodiments or their modifications.

[0093] <Sixteenth Embodiment> Fig. 39 is a plan view schematically showing the configuration of a power module 600 according to a sixteenth embodiment, with some of the configuration omitted so that the interior of the configuration can be seen. Fig. 40 is a cross-sectional view schematically showing the configuration of the power module 600 shown in Fig. 39 together with the bus bar 10, taken along line XL-XL in Fig. 39. Fig. 41 is a partial enlarged view of Fig. 40.

[0094] In the power module 600, the lead frame 6A has a step portion 18. The step portion 18 has a bottom step 18a on the bottom surface of the lead frame 6A (the surface facing the support portion SP). The bottom step 18a corresponds to the boundary between a region of the bottom surface of the lead frame 6A that faces the support portion SP (specifically, the insulating sheet 8) via the resin mold portion 4 in the Z direction and a region that faces the support portion SP (specifically, the insulating sheet 8) in the Z direction without the resin mold portion 4. The provision of the former region makes it easier to ensure a sufficient shortest distance between the main terminal portion 6Ab of the lead frame 6A and the portion of the module base 9 that is not covered by the insulating sheet 8, compared to a case where the step portion 18 is not provided (see FIG. 2 ). This improves the dielectric strength voltage between the lead frame 6A and the module base 9. The latter region may be in direct contact with the insulating sheet 8 of the support portion SP.

[0095] In the power module 600, the boundary between the main frame portion 6Aa and the main terminal portion 6Ab is defined by the lower surface step 18a. The step portion 18 may further have an upper surface step 18b on the upper surface of the lead frame 6A (the surface opposite to the surface facing the support portion SP). The height of the upper surface step 18b may be substantially the same as the height of the lower surface step 18a. In the power module 600, the upper surface step 18b is positioned so as to overlap the lower surface step 18a in a plan view. The step portion 18 is formed, for example, by half-blanking. In this case, the lead frame portion 6Aa and the main terminal portion 6Ab, which have the lower surface step 18a as their boundary, are typically included in a single member made of substantially the same material.

[0096] Note that, other than as described above, the configuration of this embodiment 16 is almost the same as the configuration of the above-mentioned embodiment 15 (Figure 36), so the same or corresponding elements are given the same symbols and their descriptions will not be repeated.

[0097] FIG. 42 is a plan view schematically illustrating the configuration of a power module 600A according to a modification of the sixteenth embodiment, in the same field of view as FIG. 41 . In the power module 600A, the upper surface step 18b is positioned offset from the lower surface step 18a toward the main frame portion 6Aa in plan view. As a result, the main frame portion 6Aa has a main portion 6Aa1 having the first slit 5 ( FIG. 39 ) and a transition portion 6Aa2, and the transition portion 6Aa2 is positioned between the main portion 6Aa1 and the main terminal portion 6Ab. The thickness of the transition portion 6Aa2 may be locally thicker between the main portion 6Aa1 of the main frame portion 6Aa and the main terminal portion 6Ab.

[0098] Fig. 43 is a plan view schematically showing the configuration of a power module 600B according to a modification of the sixteenth embodiment, in the same field of view as Figs. 41 and 42. In the power module 600B, the upper surface step 18b is positioned offset from the lower surface step 18a toward the main terminal portion 6Ab in plan view. As a result, the main terminal portion 6Ab has a main portion 6Ab1 and a transition portion 6Ab2, and the transition portion 6Ab2 is positioned between the main portion 6Ab1 and the main frame portion 6Aa. The thickness of the transition portion 6Ab2 may be locally thinner between the main frame portion 6Aa and the main portion 6Ab1 of the main terminal portion 6Ab.

[0099] In the above-described embodiment 16 of the present invention or its modified examples, the height of the upper surface step 18b may be substantially the same as the height of the lower surface step 18a, as described above. In this case, a pair of portions of the lead frame 6Aa that are not located at the step portion 18 but are adjacent to the step portion 18 on either side of the step portion 18 have a substantially common thickness. This thickness is defined as the thickness of the lead frame 6Aa. The height of the lower surface step 18a is, for example, 0.1 mm or more and less than half the thickness of the lead frame 6A. By making the height of the lower surface step 18a 0.1 mm or more, it is possible to suppress the generation of voids in the resin molded portion 4 filled between the main terminal portion 6Ab and the support portion SP (specifically, the insulating sheet 8). By making the height of the lower surface step 18a less than half the thickness of the lead frame 6A, it is possible to prevent the strength of the lead frame 6A from being excessively reduced due to the lower surface step 18a.

[0100] 44 to 46 are plan views each showing a schematic configuration of power modules 601 to 603 according to modifications of the sixteenth embodiment, in the same field of view as Fig. 39. As shown in these figures, the main terminal portion 6Ab separated from the main frame portion 6Aa by the groove portion 18 may have various shapes.

[0101] The features of the groove 18 described in the sixteenth embodiment or its modifications may be applied to other embodiments or their modifications.

[0102] Seventeenth Embodiment Fig. 47 is a block diagram showing a schematic configuration of a power conversion system to which a power conversion device 1200 according to a seventeenth embodiment is applied. This power conversion system is composed of a power supply 1100, a power conversion device 1200, and a load 1300. The power conversion device 1200 has a main conversion circuit 1201 and a control circuit 1203. The main conversion circuit 1201 has a power module according to any of the first to fourteenth embodiments or their modifications (hereinafter also referred to as power module 1202), and converts and outputs input power. The control circuit 1203 outputs a control signal for controlling the main conversion circuit to the main conversion circuit.

[0103] The power conversion device to which the power modules of the above-mentioned embodiments 1 to 14 are applied is not limited to a specific power conversion device, but below, as embodiment 15, a case where the power modules are applied to a three-phase inverter will be described in detail.

[0104] The power supply 1100 is a DC power supply and supplies DC power to the power conversion device 1200. The power supply 1100 can be configured from a variety of elements, such as a DC system, a solar cell, or a storage battery, or it may be configured from a rectifier circuit connected to an AC system or an AC / DC converter. The power supply 1100 may also be configured from a DC / DC converter that converts DC power output from a DC system into a predetermined power.

[0105] The power conversion device 1200 is a three-phase inverter connected between the power supply 1100 and the load 1300, and converts DC power supplied from the power supply 1100 into AC power and supplies the AC power to the load 1300. As shown in Fig. 47 , the power conversion device 1200 includes a main conversion circuit 1201 that converts DC power into AC power and outputs it, and a control circuit 1203 that outputs a control signal to the main conversion circuit 1201 to control the main conversion circuit 1201.

[0106] The load 1300 is a three-phase electric motor driven by AC power supplied from the power conversion device 1200. The load 1300 is not limited to a specific application, but is an electric motor mounted on various electrical devices, and is used as an electric motor for, for example, a hybrid vehicle, an electric vehicle, a railroad car, an elevator, or an air conditioning device.

[0107] The power conversion device 1200 will be described in detail below. The main conversion circuit 1201 includes switching elements and freewheel diodes (not shown). The switching elements convert DC power supplied from the power supply 1100 into AC power, which is supplied to the load 1300. The main conversion circuit 1201 can have a variety of specific circuit configurations. However, the main conversion circuit 1201 according to the fifteenth embodiment is a two-level, three-phase full-bridge circuit that can be configured with six switching elements and six freewheel diodes connected in anti-parallel to each switching element. Each switching element and freewheel diode of the main conversion circuit 1201 is configured by a power module 1202. Two of the six switching elements are connected in series to form upper and lower arms, which constitute each phase (U phase, V phase, and W phase) of the full-bridge circuit. The output terminals of each upper and lower arm, i.e., the three output terminals of the main conversion circuit 1201, are connected to the load 1300.

[0108] The main conversion circuit 1201 also includes a drive circuit (not shown) that drives each switching element. The drive circuit may be built into the power module 1202, or may be provided separately from the power module 1202. The drive circuit generates drive signals that drive the switching elements of the main conversion circuit 1201 and supplies them to the control electrodes of the switching elements of the main conversion circuit 1201. Specifically, in accordance with control signals from a control circuit 1203 (described later), the drive circuit outputs to the control electrodes of each switching element a drive signal that turns the switching element on and a drive signal that turns the switching element off. To maintain a switching element in the on state, the drive signal is a voltage signal (on signal) that is equal to or greater than the threshold voltage of the switching element. To maintain a switching element in the off state, the drive signal is a voltage signal (off signal) that is equal to or less than the threshold voltage of the switching element.

[0109] The control circuit 1203 controls the switching elements of the main conversion circuit 1201 so that the desired power is supplied to the load 1300. Specifically, the control circuit 1203 calculates the time (ON time) that each switching element of the main conversion circuit 1201 should be in the ON state based on the power to be supplied to the load 1300. For example, the main conversion circuit 1201 can be controlled by pulse width modulation (PWM) control, which modulates the ON time of the switching elements according to the voltage to be output. The control circuit 1203 then outputs a control command (control signal) to a drive circuit included in the main conversion circuit 1201 so that an ON signal is output to a switching element that should be in the ON state at each time point, and an OFF signal is output to a switching element that should be in the OFF state at each time point. In accordance with this control signal, the drive circuit outputs an ON signal or an OFF signal as a drive signal to the control electrode of each switching element.

[0110] In a power conversion device 1200 according to the fifteenth embodiment, the power modules 1202 according to the first to fourteenth embodiments or their modifications are applied as the switching elements and free wheel diodes of a main conversion circuit 1201. This makes it possible to suppress deterioration in the insulation reliability and heat dissipation characteristics of the power conversion device 1200.

[0111] In the fifteenth embodiment, an example has been described in which the power module 1202 according to any one of the first to fourteenth embodiments or their modifications is applied to a two-level three-phase inverter. However, the application of the power module 1202 is not limited to this, and the power module 1202 can be applied to various power conversion devices. Furthermore, although a two-level power conversion device has been exemplified in the fifteenth embodiment, the power conversion device may be a three-level or multilevel power conversion device. Furthermore, when supplying power to a single-phase load, the power module 1202 may be applied to a single-phase inverter. Furthermore, when supplying power to a DC load or the like, the power module 1202 may be applied to a DC / DC converter or an AC / DC converter.

[0112] Furthermore, the load 1300 of the power conversion device 1200 to which the power module 1202 is applied is not limited to the electric motor described above. That is, the power conversion device 1200 can be used not only for electric motors but also as a power supply device for, for example, an electric discharge machine, a laser processing machine, an induction heating cooker, or a contactless power supply system. The power conversion device 1200 can also be used as a power conditioner for a solar power generation system, a power storage system, or the like.

[0113] It should be noted that the embodiments can be freely combined, and the embodiments can be appropriately modified or omitted. Although the present disclosure has been described in detail, the above description is illustrative in all aspects and is not intended to be limiting. It is understood that countless variations not illustrated can be envisioned from the present disclosure.

[0114] 2 Power semiconductor chip, 2a First power semiconductor chip, 2b Second power semiconductor chip, 4 Resin molded portion, 4e Extension portion, 5 First slit, 5M Second slit, 6 Lead frame group, 6A Lead frame, 6Aa Main frame portion, 6Ab Main terminal portion, 6Ab1 First portion, 6Ab2 Second portion, 6Ab3 Third portion, 8 Insulating sheet, 9 Module base, 10 Bus bar, 15 Through hole (first through hole), 15M Through hole (second through hole), 16 Through hole (first through hole), 16M Through hole (second through hole), 17 First groove, 17M Second groove, 18 Step portion, 30 Wire (wiring member), 100, 101 to 107, 110, 111, 120, 130, 131, 140, 141, 150, 160, 170, 200 to 203, 210, 220, 230, 300, 400, 500 to 502, 600, 600A, 600B, 601 to 603 power modules, 1200 power conversion device, 1201 main conversion circuit, 1202 power module, 1203 control circuit, ED1 first end, ED2 second end, F1 first surface, F2 second surface, SP support portion.

Claims

1. A power module including a lead frame, comprising: at least one power semiconductor chip including a first power semiconductor chip; and a main frame portion that is a part of the lead frame and has a first surface on which the at least one power semiconductor chip is mounted and a second surface opposite the first surface in a first direction, the main frame portion having a first end portion with a first dimension along a second direction intersecting the first direction, the power module further comprising: a main terminal portion that is a part of the lead frame and directly adjacent to the main frame portion in a third direction intersecting the first and second directions, the main terminal portion having a second end portion connected to the first end portion of the main frame portion, the first power semiconductor chip of the at least one power semiconductor chip being closest to the main terminal portion, the power module further comprising: a support portion on which the main frame portion is mounted so as to face the second surface of the main frame portion; a resin molded portion that seals the main frame portion and the at least one power semiconductor chip and partially seals the main terminal portion, and has an outer edge in a planar view including the second direction and the third direction, wherein the outer edge has an extending portion that extends along the second direction, and the main terminal portion protrudes from the extending portion of the outer edge of the resin molded portion to the outside of the resin molded portion, and the main frame portion has a first slit or a first groove between the first power semiconductor chip and the main terminal portion in the third direction, the first slit or a first groove extending a third dimension along the second direction and having a fourth dimension in the third direction that is smaller than the third dimension.

2. The power module of claim 1, wherein said second end has a second dimension along said second direction that is smaller than said first dimension.

3. A power module according to claim 1 or 2, wherein the main frame portion has a first through hole between the first power semiconductor chip and the main terminal portion in the third direction.

4. A power module according to any one of claims 1 to 3, wherein the first slit or the first groove of the main frame portion is disposed on the support portion.

5. A power module according to any one of claims 1 to 3, wherein the support section has a module base made of metal and an insulating sheet that is placed on the module base and is thinner than the module base, and the first slit or the first groove of the main frame section is placed on the insulating sheet.

6. A power module according to any one of claims 1 to 5, wherein the main terminal portions extend only in a horizontal direction including the second direction and the third direction.

7. A power module according to any one of claims 1 to 6, wherein the main terminal portion has a first portion extending from the second end of the main terminal portion along a horizontal direction including the second direction and the third direction, a second portion extending from the first portion along a direction intersecting the horizontal direction, and a third portion extending from the second portion along the horizontal direction.

8. A power module according to any one of claims 1 to 7, wherein the at least one power semiconductor chip includes a second power semiconductor chip, the second power semiconductor chip is mounted on the first surface of the main frame portion and sealed in the resin mold portion, and the main frame portion has a second slit or second groove between the first power semiconductor chip and the second power semiconductor chip in the third direction, the second slit or second groove extending a fifth dimension along the second direction and having a sixth dimension in the third direction that is smaller than the fifth dimension.

9. The power module according to claim 8, wherein the main frame portion has a second through hole between the first power semiconductor chip and the second power semiconductor chip in the third direction.

10. A power module described in any one of claims 1 to 9, wherein the first surface of the main frame portion has a first position and a second position separated from each other by the first slit or the first groove in the third direction, and further comprising wiring members joined to the first position and the second position so as to extend above the first slit or the first groove of the main frame portion.

11. A power module including a lead frame, comprising: at least one power semiconductor chip including a first power semiconductor chip; and a main frame portion that is a part of the lead frame and has a first surface on which the at least one power semiconductor chip is mounted and a second surface opposite the first surface in a first direction, the main frame portion having a first end portion with a first dimension along a second direction intersecting the first direction, the power module further comprising: a main terminal portion that is a part of the lead frame and directly adjacent to the main frame portion in a third direction intersecting the first and second directions, the main terminal portion having a second end portion connected to the first end portion of the main frame portion, the second end portion having a second dimension along the second direction that is smaller than the first dimension, the first power semiconductor chip of the at least one power semiconductor chip being closest to the main terminal portion, the power module further comprising: a support portion on which the main frame portion is mounted so as to face the second surface of the main frame portion, a resin molded portion that seals the main frame portion and the at least one power semiconductor chip and partially seals the main terminal portion, and has an outer edge in a planar view including the second direction and the third direction, wherein the outer edge has an extending portion that extends along the second direction, and the main terminal portion protrudes from the extending portion of the outer edge of the resin molded portion to the outside of the resin molded portion, and the main frame portion has, between the first power semiconductor chip and the main terminal portion in the third direction, a through hole that extends a third dimension along the second direction and has a fourth dimension in the third direction that is smaller than the third dimension, or a plurality of through holes that are arranged along the second direction.

12. A power conversion device comprising: a main conversion circuit having a power module according to any one of claims 1 to 11, which converts input power and outputs it; and a control circuit which outputs a control signal to the main conversion circuit to control the main conversion circuit.

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