Cooling unit, semiconductor device, and method of manufacturing the cooling unit

Abstract

The cooler unit (1) for liquid cooling of a power module (30) includes an upper portion (15) and a lower portion (16) and comprises at least one insert (10) configured to be coupled to the power module (30) at the upper portion (15). The cooler unit (1) further comprises a housing (20) comprising at least one recess (21) defining an internal flow path (27) for a coolant, penetrating a wall (25) of the housing (20) to the flow path (27) and configured in geometric cooperation with the at least one insert (10), the at least one insert (10) comprising copper and disposed inside the recess (21) and laser welded to the housing (20) such that during operation the coolant flows through the flow path (27) and around the lower portion (16) of the at least one insert (10).

Description

[Technical field]

[0001] statement The present disclosure relates to a cooling unit for a power module and a method for manufacturing the cooling unit for a power module. The present disclosure further relates to a corresponding semiconductor device. [Background technology]

[0002] Power modules, used for example in automotive inverters, require coolers to dissipate heat during operation. Such coolers may require additional components to be fixed to the power module and set up a stable connection and a tight, reliable seal. Summary of the Invention [Problem to be solved by the invention]

[0003] There is a need to provide a cooler that allows for stable coupling with a power module and contributes to reliable and effective heat dissipation during operation of the power module. [Means for solving the problem]

[0004] The present disclosure relates to a cooler unit for liquid cooling of a power module, which allows a secure connection and contributes to reliable heat dissipation. The present disclosure also relates to a corresponding manufacturing method and a corresponding semiconductor device for such a cooler unit.

[0005] According to one embodiment, a cooler unit for liquid cooling of a power module comprises at least one insert and a housing. The at least one insert comprises an upper part and a lower part and is configured to be coupled to the power module at its upper part. The housing comprises at least one recess providing an internal flow path for the coolant and penetrating the wall of the housing to the flow path. The at least one recess is configured in geometric cooperation with the at least one insert such that the shapes and / or extensions such as respective heights, respective widths and / or respective lengths of the insert and recess at least partially match each other. The at least one insert comprises copper and is placed inside the recess and laser welded to the housing such that during operation the coolant flows through the flow path and around the lower part of the at least one insert. The at least one insert and the housing each comprise a respective welded area. The welded area of ​​the insert is formed on an edge or peripheral area, e.g. on a top surface, a bottom surface and / or a side wall of an edge of the insert. The welded area of ​​the housing is formed on an edge or peripheral area of ​​the housing limiting the at least one recess which may further form a support surface of the insert. The edge relates to the respective peripheral area of ​​the corresponding insert or housing. Thus, the weld joint is at least partially formed by laser welding in the weld area of ​​the side wall of the insert. The weld joint formed by laser welding can further be at least partially formed in the circumferential or peripheral direction on the top and / or bottom surface and / or side wall.

[0006] By using the described configuration, a cooler unit is realizable which allows a secure coupling to the power module and further contributes to reliable heat dissipation during operation of the power module. In particular, the cooler unit is suitable for power modules for use in high voltage applications, for example with voltages of at least 0.5 kV.

[0007] The cooler unit is specially configured to be connectable to the intended power module, with its top or the top surface of its top facing the power module. The inclusion of copper in the cooler unit allows for sufficient heat dissipation. The copper of the insert may therefore be available in sections of the cooler unit. In this respect, the insert may be made of copper entirely or in sections, the insert may include copper in the form of bare copper and / or copper alloy. With the laser welded copper insert a stable and reliable connection to the housing is set, and due to its thermal conductivity the copper insert allows for beneficial heat dissipation.

[0008] The upper and lower parts denote sections or parts of the insert, which may also be called first and second sections or parts. The upper and lower parts may realise two separate elements joined together or two parts of a common single element, such as a copper plate. The upper and lower parts may therefore denote parts of the insert formed in one piece. The upper and lower parts may comprise the same shape and the same geometrical extension or may differ from each other. In the latter case, for example, the upper part may form a plate-like part and the lower part may form a thicker cuboid or block-like part. Furthermore, the upper and / or lower parts may be partially or completely equipped with flat and / or structured surfaces.

[0009] Furthermore, it is also possible to couple an insert, which does not necessarily contain copper, to the housing, which may realize an inlay with a material and / or a shape that provides a higher thermal conductivity than the housing of the cooler unit in order to reliably dissipate heat from the power module.

[0010] According to a further embodiment, the housing comprises aluminum. In this regard, the housing may be made entirely or in sections from aluminum, and the housing may comprise aluminum in the form of bare aluminum and / or an aluminum alloy. Alternatively or additionally, the housing may also comprise copper.

[0011] Depending on the specifications regarding weight, cost and material properties, the housing can alternatively be made entirely of copper or a copper alloy. With such an arrangement, no welded joints are required and the housing and the at least one insert can be made in one piece, the at least one insert providing at least one connection area corresponding to the upper surface of the housing for coupling to the power module.

[0012] According to the above-mentioned embodiment, the copper insert is laser welded to the aluminum housing and reliably connected to the inside of the recess provided therein. At least one recess of the housing forms a cavity or an opening which is covered by at least one insert. The insert is, for example, inserted into the cavity or placed from above into the opening and laser welded at its contact edges to form a closed cooler except for the coolant inlet and outlet. Thus, in a section, the insert forms a copper cover on the upper surface of the housing. From the point of view of the assembled or mounted state, the power module is connected to the upper surface of the insert, for example by gluing, soldering, sintering and / or diffusion bonding.

[0013] Relevant to this disclosure is the recognition that conventional coolers are mechanically secured to the power module using clamping mechanisms. Such conventional configurations are relatively complex, including screw-on clamps, and require additional seals such as O-rings. In particular, the use of rubber seals, threaded connections, can result in loss of torque and, therefore, loss of reliability due to thermal cycling, and thus risk of loss of coolant due to leakage in long-term operation.

[0014] Due to the described structure of the copper insert being laser welded to the housing, no additional sealing elements are required. Furthermore, the laser welding allows the insert to be reliably connected to the housing, without the need for adhesives or weld coatings. This allows the above arrangement to be reliably and reliably assembled to form a cooler unit.

[0015] A further realization relevant to the present disclosure is that conventional welding processes have strong thermal effects on the joining partners. Here, the thermal effects on assembled power modules with plastic parts such as molded package bodies can be considered very significant. With precisely localized laser welding, the thermal effects of the welding process are clearly limited and the welding process can be carried out reliably without or with reduced endangerment of adjacent components. Depending on the configuration of the power module, the power module can be attached to the insert after the laser welding of the insert, which can realize a standalone element forming part of the cooler unit and / or forming part of the power module, for example the base plate of the bottom side of the power module.

[0016] According to a further embodiment, at least one insert comprises at least one coating partially or completely covering at least one of the upper and lower parts of the insert. For example, the at least one coating comprises nickel and covers the lower part of the insert. The nickel coating can be configured to protect the insert from corrosion due to its contact with the coolant during operation. However, the nickel coating can also be used for other purposes. Alternatively or additionally, the at least one coating comprises silver and / or gold and covers the upper part of the insert configured to provide predetermined bonding properties for bonding the cooler unit to the power module. Alternatively or additionally, a coating can be formed on one or both of the housing and the weld area of ​​the insert to improve the formation of the weld joint and the bonding of the insert to the housing. Thus, the insert may not be completely coated or may be completely or partially coated. The coating on the upper surface and / or the coating on the lower surface can be prepared from nickel, silver, gold and / or other materials suitable for providing protective and / or connecting properties and can be formed by electroless or electrolytic plating process or other applicable process.

[0017] According to a further embodiment, the lower part of the insert comprises an underside with a given surface structure facing the flow passage. The lower part can thus form a given cooling structure to provide an extensive heat exchange surface between the insert and the coolant. The lower part of the insert is at least partially in contact with the coolant as it flows through the flow passage. The shape and / or orientation of the given surface structure can be configured to at least partially provide a laminar or preferably turbulent flow of the coolant. The surface structure of the lower surface of the lower part can thus be designed to favorably influence the flow behavior of the flowing coolant. In this respect, the pressure drop and the flow rate of the coolant may also be taken into account in terms of forming the given surface structure. The surface structure can be realized, for example, by a pin-fin area using pins with a cylindrical or conical shape in order to increase the overall thermal efficiency with an increased surface area for effectively transferring heat to the coolant. Additionally or alternatively, the surface structure can comprise ribs and / or skive structures and / or serpentine channels. Alternatively, the lower part of the insert can be formed without a particular structure on its underside and thus comprise a flat surface. According to one embodiment, the insert can be a simple copper plate with a flat surface on its top and / or bottom. Cooling structures such as pins or skived fins can be incorporated into a heat sink to which the flat bottom of the insert can be attached.

[0018] According to a further embodiment, the upper part of the insert comprises a top surface with a given surface structure facing away from the flow path, which is configured to provide predetermined bonding properties for bonding the cooler unit to the power module. The given surface structure of the top surface can comprise roughness, recesses and / or ridges. Thus, the top surface can be formed as a flat surface or can comprise a predetermined roughness. Alternatively or additionally, the top surface can comprise one or more recesses or ridges for improving the bonding process and the reliability of the bonding connection to the power module. The given surface can completely cover the top surface or can be limited to the area of ​​the bonding connection with the power module.

[0019] According to a further embodiment, the housing comprises an inlet and an outlet that define the flow direction of the coolant during operation. The housing further comprises two or more recesses configured to accommodate two or more respective inserts, with at least one insert comprising copper being arranged in one of the recesses closer to the outlet than to the inlet of the housing. For cost reduction, the cooler unit may comprise one or more inserts made of aluminum. Thus, an aluminum insert may be used in the less thermally critical power modules, e.g. near the coolant inlet, while one or more copper inserts are required in the more thermally critical power modules, e.g. near the coolant outlet, due to the higher thermal conductivity of copper compared to aluminum. Alternatively or additionally, different cooling characteristics may also be achieved by different cooling structures in the lower parts of each of the inserts.

[0020] There may also be situations of power modules with different characteristics, where the most important power module is mounted on the copper insert, but not necessarily near the outlet. In addition, there may be cases where the inlet temperature is reduced or lower, leading to poorer thermal properties of the coolant. In this case, the temperature of the chips of the first power module may be higher than that of the last power module, relative to the coolant flow direction. In these cases, it is probably also preferable to have the copper insert closer to the inlet than to the outlet of the housing. The location of the copper insert or inserts should therefore be considered with respect to the specific situation in terms of improving heat dissipation.

[0021] According to a further embodiment, the cooler unit comprises three inserts each comprising copper, and the housing comprises three recesses each penetrating the wall of the housing to the flow passage, each recess being configured in geometric cooperation with an associated insert, the inserts being disposed inside their respective associated recesses and each being laser welded to the housing.

[0022] According to one embodiment, a semiconductor device comprises an embodiment of the described cooler unit and a power module with electronics coupled to the top of an insert of the cooler unit. The electronics may include chips, integrated circuits, and / or other discrete devices, in particular power semiconductor devices. The chips or other devices are typically mounted on, for example, an insulating substrate, an (insulating metal) base plate, a PCB, or a lead frame. The devices may be encapsulated in a module housing or capsule. The back side of the substrate, base plate, etc., is typically exposed for mounting to the insert. The insert may thus form a component of the described cooler unit. Alternatively, the insert may form a component of the power module, which functions as a base plate. The power module may thus comprise its own base plate and / or the insert functions as an (additional) base plate. However, when the power module is fixed to the housing, the insert is also coupled to the housing, thus forming the cooler unit described above.

[0023] According to a further embodiment, the top surface of the upper portion of the insert and the power module are bonded to each other by at least one of gluing, sintering, soldering, and bonding, or other applicable bonding methods.

[0024] According to one embodiment, a method of manufacturing one embodiment of the described cooler unit includes providing at least one copper insert and providing at least one recess in a housing. The method further includes disposing the at least one insert inside the recess such that the at least one insert contacts the housing, e.g., a periphery. The at least one insert is disposed inside the recess such that a lower portion faces a flow path in the housing. The method further includes laser welding the at least one insert and the housing together such that during operation, coolant flows through the flow path and around a lower portion of the at least one insert.

[0025] As a result of the described semiconductor device and the described manufacturing method relating to comprising or manufacturing an embodiment of a cooler unit, the described features and properties of the cooler unit are also disclosed with respect to the semiconductor device and manufacturing method, and vice versa.

[0026] The described cooler unit for liquid cooling is suitable for power semiconductor modules without pin-fin baseplates, without degrading or with little or even improved thermal performance compared to conventional modules. This also allows for thinner baseplates of the power modules to be assembled. The power module may have a baseplate with a flat backside, or the power module may not have a baseplate, such as a molded power package with an exposed backside of the die pad of a substrate, heat sink, or lead frame, or a printed circuit board.

[0027] The use of copper inserts welded to the housing allows a reduction in thermal resistance of about 10% or more compared to aluminum inserts. Better thermal performance of the setup can be achieved if the insert of the cooler unit acts as a copper pin-fin base plate due to the obviously higher thermal conductivity of copper and its higher mechanical strength which allows a thinner base plate and potentially reduces the thermal resistance depending on the respective setup. The insert or base plate is joined to the housing realizing the cooler frame, for example made of aluminum. The joining is performed by laser welding between the aluminum housing and the copper insert. A further realization related to the present disclosure is that the weld joint of bare copper or copper alloy inserts is less critical in terms of thermal effects and therefore laser welding processes can be optimally applied.

[0028] The insert defines the location where the power module is connected to the chiller unit. The described embodiments of the chiller unit enable one or more of the following advantages when using an aluminum housing with a copper insert or base plate joined to the housing by laser welding:

[0029] ●The thermal performance of the setup using at least one copper insert that can serve as a power module base plate is improved compared to the use of aluminum inserts due to the higher thermal conductivity of copper.

[0030] • Thinner base plates or inserts can be prepared compared to aluminum inserts, but also compared to pin fin base plates of power modules.

[0031] o Copper offers better mechanical stability compared to aluminium. The warping of the power module base plate in the assembly process of the power module requires sufficient thickness of the base plate and is less relevant or should not be considered.

[0032] • A complete cooler unit made from copper would be expensive and heavy to realise, but it is possible. To keep costs down, only the relevant parts of the cooler unit can be made from copper or copper alloy.

[0033] Assembly of power modules with or without a flat base plate is cost effective and less complicated.

[0034] ● Direct bonding (sintering, soldering, adhesive bonding, diffusion bonding) of (molded) power modules is possible without a base plate, but the exposed backside of the substrate, heat sink, or die pad, and without additional coating of the top surface of the copper insert (as is required, for example, for aluminum inserts).

[0035] Exemplary embodiments are described below with the aid of schematic diagrams and reference numbers. The drawings are shown below. [Brief description of the drawings]

[0036] [Figure 1] 1A-1D show an embodiment of a cooler unit for a power module in different views. [Diagram 2] 1A-1D show an embodiment of a cooler unit for a power module in different views. [Diagram 3] 1A-1D show an embodiment of a cooler unit for a power module in different views. [Figure 4] 1A-1D show an embodiment of a cooler unit for a power module in different views. [Diagram 5] 1A-1D show an embodiment of a cooler unit for a power module in different views. [Figure 6] FIG. 6 is a perspective view of an embodiment of an insert for the cooler unit according to FIGS. 1 to 5; [Figure 7] FIG. 6 is a side view of the molded power package and cooler unit according to FIGS. 1 to 5. [Figure 8] 1 is a flow chart of a method for manufacturing one embodiment of a chiller unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] The accompanying drawings are included to provide further understanding. It should be understood that the embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale. The same reference numbers indicate elements or components having the same functions. Insofar as the elements or components correspond to each other with respect to their functions in the figures, the description thereof will not be repeated for each of the following figures. For clarity, elements may not be labeled with corresponding reference numbers in all figures in some cases.

[0038] Figure 1 shows a perspective view of one embodiment of a chiller unit 1 for liquid cooling of molded power packages or power modules 30 (see also Figures 2-7). The chiller unit 1 comprises three inserts 10, each with an upper portion 15 and a lower portion 16. The inserts 10 are configured to be coupled at their respective upper portions 15 to a power module 30 or to a number of power modules 30.

[0039] The cooler unit 1 further comprises a housing 20 providing an internal flow path 27 for the coolant. The housing further comprises an inlet 22 and an outlet 23 for the coolant so that the coolant can flow through the housing 20 during operation. The housing 20 further comprises three recesses penetrating the wall of the housing 20 to the flow path 27. The walls belong to an upper part 25 of the housing 20 connected to a lower part 26 of the housing 20. The housing 20 can thus be assembled, for example, from two parts. Alternatively, the housing 20 can be made in one piece. According to the illustrated embodiment, the inlet 22 and the outlet 23 belong to the lower part 26 of the housing 20. The recesses 21 are configured in geometric cooperation with the inserts 10, the inserts 10 comprising copper or a copper alloy. Alternatively, at least one of the inserts 10 comprises copper or a copper alloy.

[0040] The upper parts 15, 25 and the lower parts 16, 26 of the insert 10 and the housing 20 respectively represent sections or parts as viewed in the stacking direction A (see Figures 3 to 7). These parts may also be called first and second sections or parts. The upper parts 15, 25 and the lower parts 16, 26 may realise two separate elements joined together or two parts of a common single element formed integrally.

[0041] The insert 10 is arranged to be positioned inside an associated recess 21 and laser welded to the housing 20 so that during operation coolant flows into the housing 20 through the inlet 22, through flow passages 27, around the lower portion 16 of the insert 10 and out of the housing 20 through the outlet 23. Figures 2 to 5 show further views of the cooler unit 1 or sections thereof.

[0042] The housing 20 comprises aluminum which is laser welded with the copper insert 10. The insert 10 and the housing 20 thus comprise respective weld areas 14, 24 where a laser weld joint is formed. The weld area 14 of the insert 10 is formed at the edge 13 of the insert 10 and may be formed in the circumferential direction (see also FIG. 5). The edge 13 can be formed as a stepped edge realizing the circumferential or peripheral side wall 17 of the top part 15 of the associated insert 10. The stepped edge 13 comprises a thinned outermost part which contributes to a reliable laser welding since the amount of laser energy required in the thinned section is reduced. The top surface 11 of the respective insert 10 may thus be formed with a protrusion or protruding area relative to the outermost edge and realizing a part of the top part 15 which is configured to be connected to the associated power module 30. If the laser irradiation is performed from the top surface, the weld area 14 of the edge 13 may also be formed with a structure for improving the laser welding process. Such surface structures may also comprise rough surfaces, recessed portions and / or protrusions for improving the attachment of the power module 30.

[0043] The respective welded areas 24 of the housing 20 are formed at the edge 28 of the housing 20 which limits the respective recess 21. The edge 28 can also be formed in the circumferential direction and can additionally realize a support surface for the respective edge 13 (see FIG. 5) of the associated insert 10. Thus, in order to firmly connect the copper insert 10 to the aluminum housing 20, a welded joint is formed in the welded areas 14, 24 in the circumferential direction or at least partially by laser welding. In FIG. 5, a cross-sectional view is shown in which the arrows indicate possible positions for the formation of the laser welded joint. Thus, by laser welding, a corresponding welded joint can be formed on the side wall 17 of the insert 10 and / or on the bottom surface of the edge 13.

[0044] The housing 20 may be locally thinned and formed and / or may include structures useful for welding, such as grooves, recesses or indentations in the weld area 24 that contribute to the beneficial formation of a laser weld joint. Such structures can be formed on the top, sides and / or bottom of the upper portion 25 of the housing 20 to direct the laser energy to predetermined locations within the weld area 14, 24. Thus, laser welding can be performed from the top side and / or bottom side relative to the stacking direction A (see Figures 3 and 7). Thus, the terms "top", "bottom", "top", "bottom" and "side" are used to refer to positions and / or orientations relative to those shown in the figures and depicted in the stacking direction A.

[0045] The insert 10 and / or the housing 20 can be provided with the welded structure described above. The insert 10 can be welded to the housing 20 from the top, the side, and / or the bottom. In the latter case, the insert 10 is laser welded to the top 25 of the housing 20 before the housing 20 is assembled, i.e., before the bottom 26 of the housing 20 is connected to the top 25.

[0046] The insert 10 may have the shape of a base plate and may project above the upper surface of the upper part of the housing 20 with respect to a stacking direction A perpendicular to the transverse direction B (see Figures 3 to 5 and 7). Part of the insert 10 may be made of aluminum, especially close to the coolant inlet 22. The insert 10 may be provided with a coating partially or completely covering the respective upper part 15 and / or the respective lower part 16. Such a coating may comprise nickel and may be formed to cover the respective lower part 16, which is in contact with the coolant during operation, in order to protect the insert 10 from corrosion.

[0047] Additionally or alternatively, a coating may comprise silver and may be formed covering the top 15 or top surface 11 of the insert 10 to provide improved bonding properties for bonding the cooler unit 1 to the associated power module 30. The power module 30 or power package is attached to the top surface of the insert 10 by gluing, sintering, soldering, diffusion bonding, or any other applicable bonding method. The back surface of the power module 30 to be bonded is provided, for example, by a base plate, or by the exposed back surface of a substrate, die pad, heat sink, or by a printed circuit board. In FIG. 7, an embodiment of a power module 30 fixed to the bottom side of the cooler unit 1 is shown in schematic cross-sectional side view.

[0048] The lower part 16 of the insert 10 can be provided with a lower surface 12 with a given surface structure facing the flow passage 27 in order to form a cooling structure and preferably provide a turbulent flow of the coolant. The lower part 16 of the insert 10 is at least partially in contact with the coolant during operation of the connected power module 30, when the coolant flows through the flow passage 27 to dissipate heat from the insert 10. The surface structure of the lower surface 12 of the lower part 16 can therefore be designed to favorably influence the flow behavior of the flowing coolant. The surface structure can be realized, for example, by a pin-fin area with pins having a cylindrical or conical shape. Additionally or alternatively, the surface structure can comprise a rib and / or skive structure. Such a skive structure on the lower surface 12 of the insert 10 is shown in FIG. 6.

[0049] The corresponding manufacturing method steps for forming the cooler unit 1 may follow the flow chart shown in Figure 8. In step S1, a copper insert 10 is provided, possibly provided with a given surface structure on its upper surface 11 and / or its lower surface 12.

[0050] In step S2, an aluminum housing 20 is provided, possibly with a predetermined structure in the weld area 24 of the edge 28.

[0051] In step S3, the inserts 10 are positioned inside the associated recesses 21 such that the inserts 10 contact the housing 20 at the periphery 13 and 28. The inserts 10 are positioned within the recesses 21 such that the respective lower portions 16 face the flow passages 27 within the housing 20.

[0052] In a further step S4, a welding process is performed by laser welding in the weld areas 14, 24 in order to firmly connect the insert 10 to the housing 20. Thus, during operation, the coolant can flow through the flow passages 27 around the lower part 16 of the insert 10 and dissipate heat from the power module 30. Thus, a closed cooler with a laser welded copper base plate is feasible.

[0053] The embodiments shown in or described by Figures 1-8 above represent exemplary embodiments of the improved chiller unit 1 and the method of manufacturing the chiller unit 1. As such, they do not constitute an exhaustive list of all embodiments. Actual arrangements and methods may differ from the embodiments shown, for example, for the chiller unit.

[0054] Reference sign [Explanation of symbols]

[0055] 1 Cooling unit 10 Cooler unit insert 11 Top of insert 12 Underside of insert 13 Insert Edge 14 Insert Welding Area 15 Top of insert 16 Bottom of insert 17 Edge sidewall 20 Cooler unit housing 21 Housing recess 22 Housing Entrance 23 Housing outlet 24 Housing Welding Area 25 Top of housing 26 Lower part of housing 27 Flow Path 28 Housing edge 30 Power Module A Stacking direction B Insert / Housing Lateral S(i) Steps of the manufacturing method for the chiller unit

Claims

1. A cooler unit (1) for liquid cooling of a power module (30), comprising: at least one insert (10) comprising an upper part (15) and a lower part (16) and adapted to be coupled together with said upper part (15) to said power module (30); a housing (20) with at least one recess (21) providing an internal flow path (27) for a coolant, penetrating a wall (25) of the housing (20) to said flow path (27) and configured in geometric cooperation with said at least one insert (10), said at least one insert (10) comprising copper and being placed inside said recess (21) and laser welded to said housing (20) such that during operation, said coolant flows through said flow path (27) and around said lower part (16) of said at least one insert (10); Equipped with - said at least one insert (10) and said housing (20) each comprise a respective welded area (14, 24), said welded area (14) of said at least one insert (10) being formed on an edge (13) of said insert (10) and said welded area (24) of said housing (20) being formed on an edge (28) of said housing (20) limiting said at least one recess (21), whereby a welded joint is formed at least partially by laser welding on said welded area (14, 24) of the side wall (17) of said insert (10); the upper portion (15) of the insert (10) comprises a top surface (11) having a given surface structure including at least one of roughness, recesses and ridges facing away from the flow passage (27) configured to provide predetermined coupling characteristics for coupling the cooler unit (1) to the power module (30); Cooler unit (1).

2. The cooler unit (1) of claim 1, wherein the housing (20) comprises aluminum.

3. 3. The cooler unit (1) according to claim 1 or 2, wherein the at least one insert (10) is provided with at least one coating partially or completely covering at least one of the upper (15) and lower (16) sides of the insert (10).

4. The cooler unit (1) of claim 3, wherein the at least one coating comprises nickel and covers the lower portion (16) of the insert (10).

5. The cooler unit (1) according to claim 3, wherein said at least one coating comprises silver and covers said upper portion (15) of said insert (10).

6. 3. The cooler unit (1) according to claim 1 or 2, wherein the lower part (16) of the insert (10) comprises a lower surface (12) having a given surface structure facing the flow passage (27) configured to provide a given flow of the coolant and a given heat exchange surface between the insert and the coolant.

7. The cooler unit (1) of claim 6, wherein the given structure comprises at least one of a pin fin area, a rib and skive structure, and a serpentine channel.

8. 3. The cooler unit (1) of claim 1 or 2, wherein the housing (20) comprises an inlet (22) and an outlet (23) defining a flow direction of the coolant during operation, the housing (20) comprises two or more recesses (21) configured to receive respective inserts, and the at least one insert (10) comprising copper is disposed in one of the recesses (21) closer to the outlet (23) than to the inlet (22) of the housing (20).

9. 3. The cooler unit (1) according to claim 1 or 2, wherein the cooler unit (1) comprises three inserts (10), each of which comprises copper, the housing (20) comprises three recesses (21), each of which penetrates the wall (25) of the housing (20) to the flow passage (27) and each of which is configured in geometric cooperation with an associated insert (10), the inserts (10) being arranged inside the respective associated recesses (21) and each of which is laser welded to the housing (20).

10. A semiconductor device comprising: - a cooler unit (1) according to claim 1 or 2, a power module (30) with electronics, which is coupled to the top part (15) of the insert (10) of the cooler unit (1); A semiconductor device comprising:

11. The semiconductor device of claim 10, wherein the insert (10) and the power module (30) are bonded together by at least one of gluing, sintering, soldering, and bonding.

12. A method for manufacturing a cooler unit (1) for liquid cooling of a power module (30), comprising the steps of: - providing at least one insert (10) comprising an upper part (15) and a lower part (16) and adapted to be coupled together with said upper part (15) to said power module (30), said at least one insert (10) comprising copper; - providing a housing (20) with at least one recess (21) providing an internal flow passage (27) for a coolant, penetrating a wall (25) of the housing (20) to said flow passage (27) and configured in geometrical cooperation with said at least one insert (10), said at least one insert (10) and said housing (20) each comprising a welded area (14, 24), said welded area (14) of said at least one insert (10) being welded to said insert (10) by said welded area (14, 24), the housing (20) is formed on an edge (13) of the housing (20) limiting the at least one recess (21), the welding area (24) of the housing (20) is formed on an edge (28) of the housing (20) limiting the at least one recess (21), and the upper part (15) of the insert (10) comprises a top surface (11) having a given surface structure including at least one of a rough surface, a recess, and a ridge facing away from the flow passage (27) configured to provide predetermined bonding characteristics for bonding the cooler unit (1) to the power module (30); - placing said at least one insert (10) inside said recess (21) so that said at least one insert (10) is in contact with said housing (20); - laser welding together said at least one insert (10) and said housing (20) so that a weld joint is formed at least partially in said welded area (14, 24) of the side wall (17) of said insert (10) and so that during operation said coolant flows through said flow passage (27) and around said lower part (16) of said at least one insert (10); A manufacturing method comprising:

Images