A power module with at least three power units

Abstract

Power module (2) comprising at least two power units (4). The present invention relates to a power module (2) comprising at least two power units (4), each of which comprises at least one power semiconductor (6) and a substrate (8). In order to reduce the construction space required for the power module and to improve heat dissipation, it is proposed that each of the at least one power semiconductor (6) is connected, in particular by material bonding, to a respective substrate (8), and that the substrates (8) of the at least two power units (4) are each directly, by material bonding, connected to a surface (24) of a common cooling body (26).

Description

[Technical field]

[0001] A power module with at least three power units. The present invention comprises at least 3 The present invention relates to a power module having two power units.

[0002] Furthermore, the invention relates to a power converter comprising at least one such power semiconductor module. [Background technology]

[0003] In such power converters, in particular switchgear modules enclosed by a housing, which are nowadays also produced in a discrete design, are generally screwed onto a heat sink, for example via a solid metal base plate. A power converter is to be understood as, for example, a rectifier, inverter, converter or DC voltage converter.

[0004] Patent document 1 describes a power semiconductor module in which the base plate is formed as a multilayer substrate and is provided with a hardened thermally conductive paste, the power semiconductor module being brought into thermal contact with a cooling body.

[0005] Patent document 2 describes a power module for mounting on a printed circuit board, the power module having a first side for mounting on a surface of a heat sink, the first side being arranged approximately parallel to the heat sink at the mounting position of the electric power module on the heat sink, and a second side having an electric connection element, the electric connection element being adjusted to electrically connect the electric power module to the printed circuit board. The electric power module can be connected to the printed circuit board and the heat sink in a simpler manner if it comprises at least one dowel-shaped fastening element or is adjusted to receive at least one dowel-shaped fastening element. The fastening element is insertable into at least one hole of the heat sink and is adjusted to accommodate a fastening clamping element, i.e. the fastening clamping element is adjusted to fasten and clamp by introduction of at least one dowel-shaped fastening element in at least one hole of the heat sink.

[0006] Patent document 3 describes a method for manufacturing a power module unit, in which a base plate is provided with a recess. This base plate is connected to a substrate carrying the power semiconductors. After the substrate has been fixed to the base plate, cooling ribs are guided into the recesses of the base plate and fixed form-lockingly and / or frictionally.

[0007] Patent document 4 describes an electrical press-in contact, in particular a press-in pin contact, for transmitting electric current and / or electric signals, which has a press-in portion and / or a mounting portion, which are mechanically connected to one another via a relief portion, which has a balance region and a stop region, which balance region allows a coupled relative movement of the press-in portion and the mounting portion and which prevents the press-in portion and the mounting portion from moving towards one another, and which stop region of the relief portion is arranged symmetrically with respect to a force center line of the electrical press-in contact, along which a press-in force can be introduced into the electrical press-in contact, which press-in force results from the electrical press-in contact being pressed into a carrier.

[0008] Patent document 5 describes a low inductance power module for wide bandgap ultrafast semiconductor power switchgear. Conductive tracks define a power bus for a switching topology with, for example, GaN E-HEMTs, where power terminals extend from the power bus through the package and provide spacing between the heat sink and the busbar that meets creepage and airflow requirements.

[0009] Patent document 6 describes an electronic device that includes an electrical component that generates heat, in particular a power semiconductor, and a cooling device for dissipating this heat, the cooling device being formed from an air cooler that is equipped with a liquid cooler, and the air cooler is disposed between the liquid cooler and the electrical component that generates heat. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] German Patent Application Publication No. 102009001722 [Patent Document 2] German Patent Application Publication No. 102010022562 [Patent Document 3] European Patent Application Publication No. 3624184 [Patent Document 4] German Patent Application Publication No. 102008007310 [Patent Document 5] US Patent Publication US2020 / 0185302 [Patent Document 6] International Publication No. 2007 / 065666 Summary of the Invention [Problem to be solved by the invention]

[0011] Against this background, the object of the present invention is to reduce the construction space required for a power module and to improve heat dissipation. [Means for solving the problem]

[0012] This problem is solved according to the invention by at least 3 The problem is solved by a power module comprising three power units, each of which includes at least one power semiconductor and a substrate, each of which is connected, in particular by material bonding, to a respective substrate, the substrates of the at least three power units being directly, material bonding, connected to a surface of a common cooling body, the cooling body being configured such that a gaseous coolant flows in a coolant flow direction, the coolant flow direction extending approximately parallel to a surface of the cooling body, the power units being arranged offset laterally with respect to the coolant flow direction, the cooling body having cooling ribs arranged extending in the coolant flow direction, and power boards arranged approximately parallel to the surface of the cooling body being connected to the power units via freely positionable contacts.

[0013] Furthermore, the above object is achieved according to the invention by a power converter comprising at least one such power module.

[0014] The advantages and preferred embodiments given below in relation to the power module can be directly applied to the power converter.

[0015] The invention is based on the consideration that by reducing the number of thermal interfaces, the space required for a power module is reduced and thus the cooling is improved. Such a power module has at least three power units, each of which comprises at least one power semiconductor and a substrate. The substrate is a dielectric material layer metallized on both sides, the dielectric material layer having a thickness d, for example, of 25 μm to 400 μm, in particular 50 μm to 250 μm. Furthermore, the dielectric material layer comprises a ceramic material, for example aluminum nitride or aluminum oxide, or an organic material, for example polyamide. In particular, the metallization comprises copper, molybdenum, gold and / or silver. Furthermore, at least one side of the metallization of the substrate may be structured. The power semiconductors are designed in particular as transistors and / or diodes, the transistors being designed for example as insulated gate bipolar transistors (IGBT), as metal oxide semiconductor field effect transistors (MOSFET) or as field effect transistors. Each at least one power semiconductor is connected to the respective substrate in particular material-bonded manner, for example via a sintered or soldered connection.

[0016] The substrates of the power units are each directly and materially connected to the surface of the common cooling body, in particular at the side facing away from the at least one power semiconductor. Directly and materially connected means a direct contact, including connection means for forming a materially connected connection, such as adhesives, solder tin, sintering paste, etc., but excluding additional connection elements, such as bonding wires, spacers, base plates, heat-conducting pastes, etc. By omitting such additional connection elements, an improved thermal coupling of the power semiconductors is achieved, and thus a better cooling. Furthermore, the direct materially connected connection saves construction space. The materially connected connection of at least three power units on a common cooling body provides a high degree of flexibility with regard to the positioning of the power units on the surface of the cooling body, which contributes to achieving an optimized heat dissipation through heat diffusion and to a maximum utilization of the surface of the cooling body.

[0017] The heat sink is designed so that a gaseous coolant flows in a coolant flow direction, which runs approximately parallel to the surface of the heat sink. The gaseous coolant is, for example, air. In particular, the power module is cooled on one side by a fan which is in fluid-technical connection with the cooling ribs of the heat sink, so that the air from the fan flows over the cooling ribs of the heat sink approximately parallel to the surface of the heat sink. Such an arrangement is inexpensive and reliable.

[0018] The at least three power units are arranged transversely offset with respect to the coolant flow direction, the offset arrangement achieving a heat spreading that leads to optimal heat dissipation.

[0019] A power board is to be understood as meaning a conductor plate, for example implemented as a printed circuit board (PCB), in particular designed in a multi-layer manner. The conductor plate contains, for example, an interface to the power unit, a driver circuit, a control circuit and / or a capacitor. A freely positionable contact is to be understood as, for example, a pin, which can be freely positioned on the board due to its structural characteristics. Such structural characteristics are, for example, legs, which allow the pin to be placed freely and stably on the board, for example by a material-bonded connection with the board, without a housing or other stabilization means, and / or a wobble circle, which facilitates the finding of the bore in the power board and leads to better stability and robustness, for example during thermal expansion during operation.

[0020] Such contacts are made, for example, from copper or copper alloys to achieve low resistance and high current carrying capacity. The freely positionable contacts achieve short conductive paths and the associated low inductance, which allows for a power unit with low impedance and low losses. Furthermore, the individual cells of the power unit can be designed cheaply and easily.

[0021] In a further embodiment, each of the power unit boards has a power output of at least 25 W. m -1 ·K-1 , especially at least 100W m -1 ·K -1 It is envisaged to have a dielectric material layer with a thermal conductivity of 0.01 to 0.05 μm and a thickness of 25 μm to 400 μm, in particular 50 μm to 250 μm. For example, the dielectric material layer is made of aluminium nitride or aluminium oxide. In particular, a plurality of substrates bonded to the cooling body surface allows the use of such thin ceramic layers, which leads to an improved thermal coupling of the power semiconductors.

[0022] A further embodiment is a power unit comprising at least one 3 It is envisaged that the two components have a common housing, which is made, for example, from plastic. The common housing saves construction space.

[0023] A further embodiment is a power unit comprising at least one 3 It is envisaged that the power modules are electrically conductively connected to one another, in particular via a bonding connection. This type of bonding connection is made, for example, via a bonding wire or a ribbon bond. For example, several identical power units can be interconnected in parallel via bonding connections, which contributes to driving higher load currents. Due to such a modular structure, the power module can be manufactured in a cheap and scalable manner.

[0024] A further embodiment contemplates that the cooling body made of a first metallic material has at least one recess on its surface, which recess is filled with a second metallic material, which has a higher thermal conductivity than the first metallic material, and at least one substrate of the power unit is directly material-bonded to the second metallic material. For example, the first metallic material is aluminum and the second metallic material is copper. Due to the recess filled with the second metallic material, an improved thermal connection of the power unit with the cooling body is achieved.

[0025] Further embodiments contemplate that the second metallic material terminates approximately flush with the surface of the cooling body. An end configured flush with the surface of the cooling body is to be understood as an end of the filling of the recess that is flat and approximately continuous with the surface of the cooling body. In particular, the second metallic material forms a flat surface that transitions to the cooling body surface almost seamlessly. By such a planar design, an optimal thermal coupling to the cooling body is achieved and mechanical and / or thermal stresses in the substrate connected to the second metallic material are avoided.

[0026] A further embodiment comprises at least 3 It is envisaged that each of the four power units is assigned a recess filled with the second metallic material, the recesses filled with the second metallic material having an area larger than the respective substrate and designed as islands protruding above the substrate at each of the substrate edges, whereby an improved thermal coupling of the power units with the cooling body is achieved.

[0027] A further embodiment contemplates that the second metallic material is introduced into the at least one recess by additive methods. For example, the second metallic material is introduced into the at least one recess by low-temperature gas spraying. The additive method allows a very low thickness of the first metallic material under the recess, in particular in comparison with casting methods, so that the cooling ribs are very close to the second metallic material, which has a higher thermal conductivity than the first metallic material, so that an improved thermal coupling to the cooling fluid is achieved.

[0028] A further embodiment provides that the power units are arranged on the surface of the cooling body such that optimal cooling of the power semiconductors is provided by heat diffusion. The power units are oriented and spaced on the cooling body, in particular in relation to the coolant flow direction, such that the waste heat generated in the power semiconductors of the power units, in particular approximately point-wise, is distributed as evenly as possible on the surface of the cooling body, thus providing heat diffusion. Such an arrangement provides a higher robustness of the power module during operation.

[0029] Further embodiments contemplate that the spacing between the power units varies in the coolant flow direction and / or transversely to the coolant flow direction, for example, one power unit each being assigned to one phase of a three-phase system, and by varying the spacing in the coolant flow direction and / or transversely to the coolant flow direction, optimal heat dissipation is achieved.

[0030] Further embodiments contemplate that the spacing between the power units is increased in the coolant flow direction. Because the coolant is heated below the power units in the coolant flow direction, the increased spacing achieves better mixing of the strongly and weakly heated coolant. Furthermore, at least greater cooling is achieved as the spacing increases, so that the increased spacing in the coolant flow direction leads to a more uniform temperature distribution on the cooling body.

[0031] Further embodiments include , own The freely positionable contacts are materially connected to the respective substrates of the power unit. .example For example, freely positionable contacts are soldered onto the respective substrate and connected to the power board using press-fit connections. 。

[0032] A further embodiment provides for the freely positionable contacts to be designed asymmetrically with respect to a force centerline along which a press-in force can be introduced into the freely positionable contacts. The asymmetric design of the freely positionable contacts allows for a higher conductor cross-section to be realized at lower tool costs compared to the prior art, which increases the current carrying capacity of the contacts.

[0033] A further embodiment provides that the heat sink is made by extrusion from an aluminum alloy with a silicon content of up to 1.0%, in particular up to 0.6%. Better thermal conductivity is achieved with extruded heat sinks, in particular in comparison with cast heat sinks, because a lower percentage of silicon can be used in the extrusion process. Extruded heat sinks made from such aluminum alloys provide better heat diffusion.

[0034] A further embodiment provides for the cooling ribs to be arranged such that the ratio of the length of the cooling ribs to the distance between them is at least 10. Such a ratio can be achieved, for example, by extrusion, with optimal heat dissipation being achieved, in particular with an extruded cooling body. Furthermore, such a ratio allows short cooling ribs, for example having a length of 20 mm to 30 mm, so that the power module with the cooling body can be processed, in particular automatically, in a soldering oven, which makes the production of the power module easier and cheaper.

[0035] A further embodiment contemplates that the heat sink has a base plate with a substantially constant first thickness of 3.5 mm to 5 mm, in particular 3.5 mm to 4 mm, whereby the cooling ribs of the base plate and the heat sink are made integrally. Such a thin base plate, which can be produced, for example, by extrusion, results in improved heat dissipation. Furthermore, such a thin base plate reduces the overall height of the power module, so that the power module together with the heat sink can be processed, in particular automatically, in a soldering oven, which makes the power module easier and cheaper to manufacture. [Brief description of the drawings]

[0036] In the following, the invention will be described and explained in more detail using examples shown in the drawings.

[0037] [Figure 1] 1 shows a schematic diagram of a first embodiment of a power module in cross section. [Diagram 2] FIG. 2 shows a schematic diagram of a second embodiment of a power module in a top view. [Diagram 3] FIG. 2 shows a schematic diagram of a third embodiment of a power module in a top view. [Figure 4] FIG. 13 shows a schematic diagram of a fourth embodiment of a power module in a top view. [Diagram 5] FIG. 13 shows a schematic diagram of a fifth embodiment of a power module in a top view. [Figure 6] FIG. 13 shows a schematic three-dimensional view of a sixth embodiment of a power module. [Figure 7] 1 shows a three-dimensional view of a freely positionable contact. [Figure 8] 1 shows a schematic diagram of a power converter including a power module. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] The examples described below are preferred embodiments of the present invention. In the examples, the described components of the embodiments each represent individual features of the present invention that should be considered independently of each other, and also develop the present invention independently of each other, and therefore are considered as part of the present invention individually or in combinations other than those shown. Furthermore, the described embodiments can also be supplemented by further features of the present invention already described.

[0039] The same symbols have the same meaning in the different figures.

[0040] 1 shows a schematic diagram of a first embodiment of a power module 2 in a cross-section. The power module 2 has, for example, two power units 4, each of which comprises a power semiconductor 6 and a substrate 8. The power semiconductors 6 are designed as transistors 10 or as diodes 12, the transistors 10 being designed, for example, as insulated gate bipolar transistors (IGBT), as metal oxide semiconductor field effect transistors (MOSFET) or as field effect transistors. For example, each of the transistors 10 is assigned a diode 12, in particular anti-parallel.

[0041] The substrates 8 of both power units 4 have a dielectric material layer 14, which comprises a ceramic material, for example aluminum nitride or aluminum oxide, or an organic material, for example polyamide. The dielectric material layer 14 has a thickness d of 25 μm to 400 μm, in particular 50 μm to 250 μm. Furthermore, the substrates 8 each have a particularly structured upper metallization 18 on the side 16 facing the power semiconductors 6 and a lower metallization 22 on the side 20 facing away from the power semiconductors 6, which are each directly material-bonded to a surface 24 of a common cooling body 26. The upper metallization 18 and the lower metallization 22 are made, for example, from copper. The material-bonded connection 28 to the cooling body 26 is made by soldering or sintering. Direct material-bonding contact includes connecting means for forming a material bond, such as adhesives, solders, sintering pastes, etc., but excludes additional connecting means, such as additional conductors, bonding wires, spacers, base plates, heat-conducting pastes, etc. The sides 30 of the power semiconductors 6 facing the substrate 8 are connected to the upper metallization 18 of the substrate 8 via material-bonding connections 28, which are also produced by soldering or sintering. The sides 32 of the power semiconductors 6 facing away from the substrate 8 are connected to the upper metallization 18 of the substrate 8 via bonding connections 34, which may for example include at least one bonding wire, at least one ribbon bond, and / or other means for producing a bonding connection.

[0042] The transistors 10 in Fig. 1 are designed, for example, as IGBTs, whose collector contacts C are connected on the side 30 of the power semiconductor 6 facing the substrate 8 to the upper metallization 18 of the substrate 8 via respective material-bonding connections 28. The emitter contacts E of the transistors 10 implemented as IGBTs are electrically insulated therefrom and connected to the upper metallization 18 of the substrate 8 via a bonding connection 34. The gate contacts of the transistors 10 and the bonding connections of the diodes 12 are not shown in Fig. 1 for reasons of clarity.

[0043] The power boards 36, which are arranged so as to extend substantially parallel to the surface 24 of the cooling body 26, are connected to the power units 4 via freely positionable contacts 38 which are materially connected to the upper metallization 18 of the respective substrate 8 of the power units 4. The freely positionable contacts 38 have elastically flexible portions and are connected to the power boards 36, for example by means of a press-fit connection.

[0044] The cooling body 26 is made from a first metallic material 39. Its surface 24 is provided with recesses 40 filled with a second metallic material 42, which has a higher thermal conductivity than the first metallic material 39. For example, the first metallic material 39 is aluminum and the second metallic material 42 is copper. 3 Each of the two power units 4 is assigned a recess 40 filled with a second metallic material 42, which ends approximately flush with the surface 24 of the cooling body 26, and the metallization 22 on the underside of each substrate 8 is materially connected to the second metallic material 42. In particular, the second metallic material 42 is introduced into the recess by means of a layer-by-layer process, for example by means of low-temperature gas spraying. Each power unit 4 may be assigned a dedicated sensor, in particular a temperature sensor, for monitoring the temperature of the power semiconductors 6.

[0045] 2 shows a schematic diagram of a second embodiment of a power module 2 in a top view. The cooling body 26 is configured, for example by cooling fins, such that a gaseous coolant flows in a coolant flow direction 44, which runs approximately parallel to the surface 24 of the cooling body 26. The gaseous coolant is, for example, air, which flows in the coolant flow direction 44 across the cooling fins of the cooling body 26 via a fan. The power module 2 comprises, for example, two power units 4, which are spaced apart on the surface 24 of the cooling body 26 in such a way that optimal cooling of the power semiconductors 6 occurs by thermal diffusion. Furthermore, the power units 4 have a rectangular base surface with identical dimensions x, y. In order to achieve optimal cooling of the power semiconductors 6, the power units 4 are arranged with a first lateral displacement x1, viewed laterally, relative to the coolant flow direction 44. In addition, the power units 4 are spaced apart by a longitudinal displacement y1, viewed laterally, relative to the coolant flow direction 44. Due to the size of the surface 24 of the cooling body 26, the lateral displacement x1 and the longitudinal displacement y1 are smaller than the respective dimensions x, y of the power unit 4. Due to the material-bonded connection of the power units 4 with the cooling body 26, fewer attachment points 46 are required. For example, each power unit 4 is assigned two attachment points 46, and the cooling body 26 is at least 3 2 corresponds to the design of FIG. 1.

[0046] 3 shows a schematic diagram of a third embodiment of a power module 2 in a top view, where two power units 4 have a common housing 48. Both power units 4 of the power module 2 are conductively connected to each other via bonding connections 34, which have a number of bond wires, ribbon bonds, and / or other means for forming the bonding connections 34. For example, the housing 48 may include a half-bridge circuit for high current applications, where two half-bridges, each assigned to one power unit 4, are connected in parallel to drive a higher load current. The further design of the power module 2 of FIG. 3 corresponds to the design of FIG. 2.

[0047] 4 shows a schematic diagram of a fourth embodiment of a power module 2 in top view, which comprises three power units 4. The spacings x1, x2, y1, y2 between the power units 4 vary in the coolant flow direction 44 and transversely to the coolant flow direction 44. To ensure approximately uniform cooling of the power units 4, they are arranged such that the spacings y1, y2 between the power units 4 increase in the coolant flow direction 44. The further design of the power module 2 of FIG. 3 corresponds to the design of FIG. 2.

[0048] Fig. 5 shows a schematic diagram of a fifth embodiment of the power module 2 in a top view, in which, in addition to varying the spacings x1, x2, y1, y2 between the power units 4, additional heat spreading is achieved by a different arrangement of the components on the substrate 8. In particular, the power semiconductors 6 are arranged on the respective substrates with freely positionable contacts 38 in such a way that optimal cooling of the power semiconductors 4 occurs. The area of ​​the respective substrates 8 can be changed for greater heat spreading. The further design of the power module 2 of Fig. 5 corresponds to the design of Fig. 4.

[0049] 6 shows a schematic three-dimensional view of a sixth embodiment of a power module 2, which comprises three power units 4. Each of the power units 4 has a housing 48 with a housing cover 50, which is shown in a see-through state in the front power unit 4. The heat sink has a base plate 51 with cooling ribs 52 arranged extending in the coolant flow direction 44, which are connected to the base plate 51, the base plate 51 and the cooling ribs 52 of the heat sink 26 being designed integrally. The base plate 51 has a substantially constant first thickness d1 of 3.5 mm to 5 mm, in particular 3.5 mm to 4 mm, whereas the ribs have a second thickness d2 smaller than the first thickness d1 of the base plate 51. For example, the cooling ribs 52 are arranged transversely to the coolant flow direction 44 at equal intervals.

[0050] The cooling body 26 is manufactured by extrusion from an aluminum alloy, which has a silicon content of, for example, 0.1% to 1.0%, in particular 0.1% to 0.6%. Furthermore, the cooling ribs 52 are arranged such that the ratio of the length l of the cooling ribs 52 to the spacing a between the cooling ribs 52 is at least 10, i.e. l / a≧10. The further design of the power module 2 of FIG. 6 corresponds to the design of FIG. 4.

[0051] FIG. 7 shows a three-dimensional view of the freely positionable contact 38. The freely positionable contact 38 has a press-in area 53, which can be connected to the power board 36, and is designed asymmetrically with respect to a force center line 54 along which a press-in force can be introduced into the freely positionable contact 38. A positioning aid 56 is attached to the central part 55 for aligning the freely positionable contact 38, for example in a soldering jig. The lower part 58 of the freely positionable contact 38 is designed as an asymmetric relief, which has an elastically bendable part 60 and a stopper 62 arranged parallel thereto, which is separated from the foot 64 by a gap width s. The foot 64 is designed for a material-bonding connection, for example by soldering or sintering. In particular, the freely positionable contact 38 is material-bondingly connected via the foot 64 to the upper metallization 18 of the substrate 8. The elastically bendable part 60 has an S-shaped elastic form with a defined elastic path. As a result, in the relief, forces occurring during the pressing process or during operation, for example caused by shaking, can be absorbed. Furthermore, the elasticity allows tolerances to be compensated for. In particular, the spring constant of the elastically bendable part 60 is generated by a cross-sectional reduction by stamping. The further design of the freely positionable contact 38 of FIG. 7 corresponds to the design of FIG. 1.

[0052] 8 shows a schematic diagram of a power conversion device 66 including a power module 2. The power conversion device 66 may include a plurality of power modules 2.

[0053] In summary, the present invention comprises at least 3 The present invention relates to a power module 2 with four power units 4, each of which comprises at least one power semiconductor 6 and a substrate 8. In order to reduce the construction space required for the power module and to improve heat dissipation, each of the at least one power semiconductor 6 is connected, in particular by material bonding, to a respective substrate 8, and at least 3It is proposed that the substrates 8 of the two power units 4 are each directly material-bondedly connected to a surface 24 of a common cooling body 26 . [Explanation of symbols]

[0054] 2 Power Module 4 Power Unit 6. Power Semiconductors 8 Substrate 10. Transistor 12 Diodes 14 Insulating material layer 18 Metallization section 22 Metallization section 24 Surface of cooling body 26 Cooling body 44 Coolant flow direction 52 Cooling rib

Claims

1. A power module (2) comprising at least three power units (4), each of the power units (4) including at least one power semiconductor (6) and a substrate (8); At least one of the power semiconductors (6) is connected to a respective one of the substrates (8); the substrates (8) of the at least three power units (4) are respectively connected by direct material bonding to a surface (24) of a common cooling body (26); The cooling body (26) is configured so that a gaseous coolant flows in a coolant flow direction (44), the coolant flow direction (44) extends substantially parallel to the surface (24) of the cooling body (26); the power units (4) are arranged transversely offset with respect to the coolant flow direction (44); The cooling body (26) has cooling ribs (52) arranged to extend in the coolant flow direction (44), a power board (36) arranged to extend substantially parallel to the surface (24) of the cooling body (26) and connected to the power unit (4) via freely positionable contacts (38); Power module (2).

2. The substrates (8) of the power units (4) each have a power rating of at least 25 W·m －１ K －１ 2. The power module (2) of claim 1, further comprising a dielectric material layer (14) having a thermal conductivity of 0.1 μm and a thickness d of 25 μm to 400 μm.

3. The power module (2) according to any one of claims 1 or 2, wherein the substrates (8) each have a layer (14) of dielectric material having a thickness (d) of between 25 μm and 400 μm.

4. The power module (2) according to any one of claims 1 to 3, wherein at least three of the power units (4) have a common housing (48).

5. 5. The power module (2) according to any one of claims 1 to 4, wherein at least three of the power units (4) are conductively connected to each other.

6. The cooling body (26) made of a first metallic material (39) has at least one recess (40) on its surface (24), the recess (40) being filled with a second metallic material (42), the second metallic material (42) having a higher thermal conductivity than the first metallic material (39), 6. The power module (2) according to claim 1, wherein at least one substrate (8) of the power unit (4) is connected to the second metallic material (42) by direct material bonding.

7. The power module (2) of claim 6, wherein the second metallic material (42) terminates substantially flush with the surface (24) of the cooling body (26).

8. 8. The power module (2) according to claim 6 or 7, wherein each of the at least three power units (4) is assigned a recess (40) filled with the second metallic material (42).

9. 9. The power module (2) according to any one of claims 6 to 8, wherein the second metallic material (42) is introduced into the at least one recess (40) by a layer-by-layer process.

10. 10. The power module (2) of claim 1, wherein the spacings (x1, x2, y1, y2) between the power units (4) vary in the coolant flow direction (44) and / or transversely to the coolant flow direction (44).

11. The power module (2) according to any one of the preceding claims, wherein the spacings (y1, y2) between the power units (4) increase in the coolant flow direction (44).

12. 12. The power module (2) according to any one of claims 1 to 11, wherein the freely positionable contacts (38) are materially connected to the substrate (8) of each of the power units (4).

13. 13. The power module (2) according to any one of claims 1 to 12, wherein the freely positionable contacts (38) are designed asymmetrically with respect to a force centre line (54).

14. 14. The power module (2) according to any one of the preceding claims, wherein the freely positionable contacts (38) have resiliently bendable portions (60).

15. The freely positionable contact (38) has a stopper (62) arranged parallel to the resiliently deflectable portion (60), The stopper is spaced from the leg (64) by a gap width (s); The leg (64) is configured for materially bonded connection; the elastically bendable portion (60) has an S-shaped elastic configuration with a defined elastic path; A power module (2) according to claim 14.

16. 16. The power module according to any one of the preceding claims, wherein the cooling body (26) is manufactured by extrusion pressing from an aluminium alloy with a silicon content of up to 1.0%.

17. 17. The power module (2) of claim 1, wherein the cooling ribs (52) are arranged such that a ratio of a length (l) of the cooling ribs (52) to a spacing (a) between the cooling ribs (52) is at least 10.

18. The cooling body (26) has a base plate (51) having a substantially constant first thickness d1 of 3.5 mm to 5 mm; 18. The power module (2) according to any one of the preceding claims, wherein the base plate (51) and the cooling ribs (52) of the cooling body (26) are designed integrally.

19. A power converter (66) comprising at least one power module (2) according to any one of claims 1 to 18.

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