Method for producing cooling assembly and cooling assembly for power electronic component

Abstract

The invention relates to a method for producing a cooling assembly (20) for a power electronic component (2), comprising the following steps: providing a powder metallurgical material and shaping or pressing the material into a green body; sintering the green body into a blank (11); according to the invention, the parison (11) is shaped into a cooling device (1) having a cooling structure with an enlarged surface, which cooling structure comprises a plurality of cooling projections (6), which are shaped by means of a forming tool (15) to which pressure can be applied, in such a way that the cooling projections (6) are formed into the cooling device (1) by means of the forming tool (15). Pressing a partial section of the parison (11) into the shaped recess (17) of the forming tool (15) and leaving a base section (4), which connects the individual cooling projections (6), at this time; and bonding the cooling device (1) to the metal casting (19) in a bonded manner by fusion welding, in particular laser welding or brazing.

Description

Technical Field

[0001] The invention relates to a method for manufacturing a cooling assembly for power electronic components, the method comprising the following steps: providing a powder metallurgical material and shaping or pressing the material into a green body, sintering the green body into a green body, and shaping the green body into a cooling device having a cooling structure with an enlarged surface.

[0002] The present invention also relates to a cooling assembly for cooling power electronic components, the cooling assembly comprising a cooling device as an assembly platform for at least one power electronic component, the cooling device also being fixed on a metal component, the cooling device having a first surface on its base section for assembling the at least one power electronic component, and a second surface of the base section being opposite to the first surface, the second surface having a cooling structure comprising a cooling protrusion. Background Art

[0003] So-called power electronic components, such as power semiconductors, are well known from the prior art. Such components are frequently used, for example also in motor vehicles. It is also known that these components generate a relatively large amount of heat during operation, which usually has to be dissipated with the aid of a cooling medium. For this purpose, a wide variety of coolers are known from the prior art.

[0004] Thus, for example, DE112007000829B4 describes an assembly consisting of an inverter and a cooler for cooling the inverter, the cooler comprising the following components: a substrate having a surface on which an inverter is provided; a heat dissipation member fixed to another opposite surface of the substrate and surrounding an area opposite to an area on one of the surfaces of the substrate on which the inverter is provided; a main pipe, the main pipe being away from the other surface of the substrate and defining a space between the main pipe and the substrate, the space being constructed so that a coolant can be directed to the space and the space enables the coolant to come into contact with the heat dissipation member; and a sub-pipe, the sub-pipe extending from the main pipe toward the substrate and the sub-pipe being opposite to an area of ​​the substrate on which the inverter is provided, thereby allowing the sub-pipe to meet the coolant supplied to the main pipe on the other surface of the substrate in an area opposite to the area on which the inverter is provided, the coolant supplied to the main pipe being separated from the coolant supplied to the space until it is discharged from the sub-pipe.

[0005] So-called pin-fin coolers are also described in the prior art, which are surrounded by a cooling medium and thus transfer heat from the pins to the cooling medium. DE102019108106A1, for example, describes a cooler for power semiconductors in an inverter, which is designed in two parts and comprises: a base plate as a first component, which can be attached to the power semiconductor in a heat-conducting manner; a cooling body as a second component, which is arranged on the base plate and has at least one corrugated recess, which is constructed to pass through from the side of the cooling body facing away from the base plate to the side facing the cooling body; the first component and the second component are connected to each other and are coated with a coating that protects the two components from electrochemical reduction.

[0006] DE102018216859A1 discloses a device for cooling a component, which comprises: a first base body and a second base body; cylindrical and / or conical first cooling ribs constructed in the first base body, through which a coolant can flow; and cylindrical and / or conical second cooling ribs constructed in the second base body, through which a coolant can flow, the second base body being joined to the first base body in such a way that the second cooling ribs are arranged between the first cooling ribs without contacting the first base body.

[0007] Cooling devices for power electronics systems usually have a structure consisting of bumps on their surface. In order to increase the cooling capacity, it is advantageous to have a surface with bumps that is as large as possible, through which the cooling fluid can flow. However, this is limited by the mechanical strength of the bumps, since the bumps can only be reduced to a minimum size in terms of their cross section. By reducing the bumps in relation to the cross section, a plurality of bumps can be provided per unit area, so that the cooling efficiency can be improved due to the larger surface area thus provided. Summary of the invention

[0008] The object of the present invention is to improve the cooling capacity of a cooling arrangement for power electronic components, which is to be produced in a resource-saving manner.

[0009] The object of the present invention is achieved by a method for producing a cooling assembly for a power electronic component, the method comprising the following steps:

[0010] - Providing a powder metallurgical material and forming or pressing the material into a green body;

[0011] - sintering the green body into a formed body;

[0012] - forming the preform into a cooling device having a cooling structure with an enlarged surface, the cooling structure comprising a plurality of cooling projections, the cooling projections being formed by means of a forming die that can be loaded with pressure, in that a partial section of the preform is pressed into a shaped recess of the forming die and a base section is left behind, which connects the individual cooling projections, in particular supports the individual cooling projections or holds the individual cooling projections together in one piece; and

[0013] The cooling device is integrally joined to the metal casting by welding, in particular laser welding or soldering.

[0014] In addition, the object of the present invention is achieved by a cooling assembly for cooling power electronic components, the cooling assembly comprising a cooling device as an assembly platform for at least one power electronic component, the cooling device being also fixed on a metal component, the cooling device having a first surface on its base section for assembling the at least one power electronic component, and having or defining a second surface opposite to the first surface, the second surface having a cooling structure comprising a cooling protrusion, wherein the base section and the cooling protrusion are composed of a sintered material, the cooling protrusion is manufactured by material forming of the base section, the metal component is a casting, and the base section of the cooling device is material-lockedly joined to the metal casting by fusion welding, in particular laser welding, or by brazing, and a liquid-tight connection between the cooling device and the casting is simultaneously established by the material-locked joining.

[0015] The advantage here is that by shaping the sintered preform into a cooling device with cooling projections, no waste material is generated for its production, as is the case, for example, in machining. In addition, all cooling projections of the cooling device can be produced simultaneously, whereby a corresponding increase in productivity can be achieved. The advantage here is that, although the preform already has a predetermined strength due to the sintering, it can be shaped more easily than solid material due to the porosity. The shaping process can provide a cooling device with a larger surface, whereby the cooling power of the cooling device can be improved.

[0016] The component combination consisting of a cooling device (also referred to as a primary cooling body) manufactured by powder metallurgy and a metal casting produces a cooling assembly for power electronic components, for example, for power improvement of semiconductor components. The relatively high thermal conductivity of the cooling device manufactured by powder metallurgy compared to the casting can obtain a fast and intensive heat conduction of the power electronic components. The material-locked connection between the cooling body and the metal casting assists in supporting the smallest possible heat transfer resistance and thus improves the further conduction of heat energy into the metal casting. The cooling assembly manufactured according to the given method has a favorable cooling power and cooling characteristics for power semiconductor components. In addition to providing performance advantages, the multi-piece, integrally joined cooling assembly also provides production technology advantages, such as mass production that is as low-cost as possible and also quality-oriented.

[0017] According to an advantageous embodiment, it can be provided that the cooling projection is formed into a cylindrical or conical shape by means of the recess in the forming mold. This allows a cooling projection that is well or constantly reproducible to be obtained while applying the smallest possible forming pressure. By avoiding or minimizing sharp edges, sharp corners or acute-angled sections, undesired deformations of the cooling projection can be prevented.

[0018] According to an alternative embodiment, the cooling projection can have a prismatic, triangular, oval, teardrop-shaped or similar shape in its cross section relative to the height axis.

[0019] According to an advantageous design variant, it can be provided that the cavity for the cooling medium is defined or at least partially delimited by the metal casting, the cooling device is inserted into the wall penetration of the metal casting, and the wall penetration is closed liquid-tightly by the cooling device without a separate or additional sealing element. As a result, the cooling component can be manufactured with high functionality and high power and also as low cost as possible. The omission of separate sealing elements brings production technology advantages and can contribute to the long-term stability of the sealing. In addition, this contributes to the achievable cooling power of the cooling component. Therefore, in particular, high-power electronic semiconductors with high cooling requirements can also be reliably temperature-controlled.

[0020] According to another embodiment of the invention, it can be provided that the cooling device has a stepped connection groove, in particular a so-called single connection groove, produced by forming with the forming die or another forming die on its outer circumference, which is designed or used to abut against a delimited section of a wall penetration of a metal casting. Such a stepped single-opening groove can be produced relatively simply and with relatively high dimension accuracy during the forming process of the cooling device. Generally, complex reworking can be omitted. This dimensional accuracy is advantageous for the tightness of the joint and for the process-reliable process of the material-locking connection of the cooling device to the metal casting.

[0021] In the production method, provision can also be made that the delimiting section of the wall penetration is machined before the materially bonded connection with the cooling device, so that a flat contact surface for the cooling device is achieved. This allows the sealing and heat transfer of the joint between the cooling device and the casting to be optimized or favored, so that an improved cooling assembly can be achieved.

[0022] According to one embodiment of the present invention, it can be provided that the end section of the cooling projection facing away from the base section extends into the cavity of the metal casting, and the power electronic component is fixed on the first surface of the base section facing away from the cooling projection. The cooling structure that increases the surface of the cooling device is thus exposed to a cooling medium, such as a coolant, or is circulated by a cooling medium. During the pressing and sintering process, the first surface of the base section facing away from the cooling projection can be made sufficiently flat, so that good heat conduction between the power electronic component and the cooling device produced by powder metallurgy can be ensured.

[0023] According to a further measure, provision can be made for a laser beam welding device to be used for the integrally bonded joining, with which a fillet weld is formed between the circumferential side surface of the cooling device and the casting. This allows process-reliable mass production and a reliably sealed connection between the cooling device and the casting. This means that tolerances or changing gap dimensions have little or relatively little influence on the quality of the welded connection.

[0024] It may also be expedient to carry out the shaping of the preform into the cooling device in a plurality of shaping steps. This allows a high quality or dimensional accuracy of the cooling device to be achieved, so that a joining process for achieving a material-locking connection of the cooling component can be carried out in a process-reliable manner. Furthermore, when using shaping dies that are adapted in stages and are shaped differently in each case, low maximum pressures can be achieved and thus energy-efficient, energy-saving production can be achieved.

[0025] The cooling projections on the second surface of the base section can be cylindrical or conical. Such cooling projections can be produced relatively process-reliable or relatively reproducibly by embossing a sintered material. This is mainly because the sintered material or the preform comprises a relatively soft metal, in particular more than 97.5% by volume of aluminum or 99% by volume of copper.

[0026] A high-performance and yet as cost-effective and energy-saving cooling component can be achieved by an embodiment in which the metal casting defines or at least partially delimits a cavity for a cooling medium, the cooling device is inserted into a wall opening of the metal casting, and the wall opening is closed liquid-tightly by the cooling device without a separate sealing element.

[0027] A high-performance, robust and at the same time energy-saving or weight-optimized, in particular lightweight cooling component can also be achieved in that the cooling device has a stepped interface groove on its outer circumference, which abuts against a delimiting section of the wall penetration of the metal casting in a load-transmitting and heat-conducting manner.

[0028] According to another embodiment, the casting can be an aluminum die casting and the sintered material of the cooling device consists mainly of aluminum or mainly of copper. With such a component pair, an advantageous interaction can be achieved with respect to cooling performance, cost efficiency and manufacturability.

[0029] It can also be provided that at least some of the cooling protrusions have a higher density in their head section facing away from the base section than the other cooling protrusions and / or at least some of the cooling protrusions have a different shape in the head section than the other cooling protrusions. The height calibration or height adjustment of the cooling protrusions can be effectively achieved or can be well performed by means of the forming die with the applied force. Therefore, a cooling protrusion that can be well adapted to the corresponding application field can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to better understand the present invention, the present invention is described in detail with reference to the following drawings.

[0031] Respectively in a greatly simplified diagram:

[0032] Figure 1 A side view showing a cooling device together with a component to be cooled;

[0033] Figure 2 An oblique view showing a cooling device;

[0034] Figure 3 A variant embodiment of the preform is shown;

[0035] Figure 4 An embodiment variant of a tool for producing a cooling device is shown;

[0036] Figure 5 A cross-sectional view showing one embodiment of a multi-piece, integrated cooling assembly;

[0037] Figure 6 A cross-sectional view showing another embodiment of a multi-piece, integrated cooling assembly;

[0038] Figure 7 A partial view showing a tool for adjusting the height of the cooling projections. DETAILED DESCRIPTION

[0039] First of all, it should be pointed out that in the different described embodiments, the same parts are provided with the same reference numerals or the same component names, and the disclosure contained in the entire description can be transferred to the same parts with the same reference numerals or the same component names. The selected positional descriptions in the description, such as top, bottom, sideways, etc., also refer to the directly described and shown figures and these positional descriptions are transferred to the new positions in the case of a change in position.

[0040] exist Figure 1 A side view of the cooling device 1 is shown in FIG.

[0041] The cooling device 1 is used to cool a component 2 or a plurality of components 2 or an assembly. To this end, the cooling device 1 is placed with a first surface 3 , in particular directly against at least one component 2 , and is therefore preferably in direct contact with the component 2 for heat exchange.

[0042] Component 2 is preferably an electronic component, in particular a so-called power electronic component or a high-power electronic component or a power semiconductor or a high-power semiconductor, but it can also be implemented differently. Such a component 2 or an assembly composed of these components 2 / having these components can be particularly configured for power in the range of several kilowatts to megawatts. Such a component 2 is used, for example, to convert electrical energy using switching electronic components. Typical applications are converters or frequency converters in the field of electrical drive technology, solar inverters for energy grids or switching power supplies (usually converting AC voltage to DC voltage through a rectifier and converting DC voltage to AC voltage through an inverter) for regenerative generation, converters for wind power equipment, control systems in drive technology for electric drive systems of electric vehicles or hybrid vehicles, battery management systems, etc., for example. Power electronic components can be semiconductors, in particular so-called power semiconductors, such as IGBTs.

[0043] Since such a component 2 is known per se from the relevant prior art, reference is made to this prior art in order to avoid a repetition of details.

[0044] The cooling device 1 comprises a base section 4, which also forms the back side or the first surface 3 of the cooling device 1, and the base section 4 has or is formed with a cooling structure on a second surface 5 lying opposite the first surface 3. In particular, the base section 4 of the cooling device 1, which is in the form of a square or plate, for example, forms the cooling structure on its second surface 5. The cooling structure is formed by cooling projections 6, which are arranged on the base section 4 protruding from the second surface 5 and are connected to it in one piece, such as this can also be seen from Figure 2 In other words, in a preferred embodiment variant, the cooling device 1 consists of only one component. Regardless of this unity, within the scope of the invention, there is the possibility that, for each component 2 or an assembly consisting of / having at least one such component 2, a plurality of cooling devices 1 can be combined with one another to form a cooling device group according to the invention. Thus, a plurality of cooling devices 1 can also be assembled in a modular manner to form a cooling device group.

[0045] The base section 4 and the cooling projections 6 are produced from sintered material or are formed from them. Furthermore, the cooling projections 6 are produced from the base section 4 by forming, in particular by mechanical forming, preferably without machining, from the material of the base section 4 .

[0046] In a preferred embodiment variant, the density of the base section 4 and the cooling projections 6 is at least 98%, in particular at least 98.5%, preferably at least 99%, of the solid density of the material used.

[0047] Solid density refers to the density of a cooling device produced by melt metallurgy from the same material, ie a component consisting of solid material. Solid material refers to a metallic material which, apart from defects, has no pores, as are usually present in sintered components.

[0048] The cooling device 6 is provided to be circulated with a cooling medium, for example water, so that the heat absorbed by the cooling device 1 is transported away via the cooling medium. The cooling device 1 is preferably designed as a so-called pin-fin cooler.

[0049] The cooling projections 6 of the embodiment variant shown are preferably designed in the form of a cylinder or a truncated cone. However, they can also have different shapes, for example, another cross section that tapers toward the cooling projection head 7, for example, a truncated pyramid design. According to one embodiment variant, several or all cooling projections 6 can be designed in the form of mushrooms in the head region, as in this Figure 7 Indicated by dotted line.

[0050] The cross section of the cooling projection 6 with respect to its height relative to the base section 4 can be circular, oval, rhombus-shaped, in the form of a teardrop or the like.

[0051] Furthermore, all cooling projections 6 can be designed identically. However, it is also possible to arrange or combine cooling projections 6 having different shapes on the base section 4 .

[0052] The height 8 of the cooling projection 6 above the second surface 5 of the base segment 4 can preferably be between 2.5 mm and 40 mm.

[0053] In the simplest embodiment of the cooling device 1 , all cooling projections 6 of the cooling device 1 have the same height 8 within a tolerance range. However, it is possible within the scope of the invention for some cooling projections 6 to have a smaller height than the remaining cooling projections 6 .

[0054] Furthermore, it can be provided that between 300 and 1300, in particular between 300 and 1000, for example between 300 and 750, cooling projections 6 are arranged or formed per square dm of the second surface. In particular, this number has proven to be advantageous with regard to the production of the cooling device 1, i.e. with regard to the forming of the base segment 4 or the preform 11 into the cooling projections 6, since damage to the cooling projections 6 or incompletely formed cooling projections 6 can thereby be avoided or reduced.

[0055] In particular, from Figure 1 As can be seen, according to an embodiment variant of the cooling device 1, it can be provided that the first surface 3 of the base section 4 is formed with a flat surface. However, there is also the possibility that the first surface 3 is formed with one or more recesses 9, in which the component 2 is at least partially accommodated. This allows for better attachment of the component 2 to the cooling device 1. The component 2 can usually be bonded or screwed or welded or sintered to the cooling device 1, for example.

[0056] At least one recess 9 can be produced simultaneously with the cooling projection 6 during the production of the cooling projection 6 . By using or forming the at least one recess 9 on the first surface 3 , it is also possible to produce a cooling projection 6 having a height 8 greater than the height of the remaining cooling projections 6 .

[0057] If you can Figure 2As can be seen, the cooling device 1 has at least one further structural element 10, which is designed as a protuberance, on the second surface 5 of the base section 4. The structural element 10 is a cylinder in the shape shown, but can also have other cross sections, for example a rhombus. With the structural element 10, a further surface can be provided on the cooling device 1 above the plane of the cooling projection 6. Therefore, the height of the structural element 10 can be greater than the cooling projection 6. However, it is also possible that the height of at least one structural element 10 is less than or equal to the cooling projection 6. In addition, more than one structural element 10 can be provided, and a plurality of structural elements 10 can be designed, for example, in the same or different shapes and / or heights.

[0058] The structural element 10 can be provided, for example, for screw connection, as a reinforcement, as a spacer or as a stop.

[0059] The structural element 10 is preferably not subjected to mechanical post-processing, but is pressed together with the net shape or nearly net shape quality or produced by powder metallurgy during the pressing of the preform 11 for producing the cooling device 1. Thus, the structural element 10 or the structural elements 10 are preferably designed as one piece or integrated with the base section 6, just like the cooling projection 6.

[0060] Sintered powders or powders used in powder metallurgy, in particular metals, are used to produce the cooling device 1. Sintered powders with correspondingly good thermal conductivity are preferably used. In particular, sintered powders based on aluminum or aluminum alloys or based on copper or copper alloys or MMC powders (metal matrix composites) are used, which contain copper powder or aluminum powder.

[0061] The cooling device is manufactured in a powder metallurgical manner according to the powder metallurgy method. Therefore, the cooling device 1 is preferably a sintered component. For this purpose, a green body is produced in a corresponding die (die) from a sintering powder that can be produced from individual (metal) powders by mixing, and the powder can be used pre-alloyed if necessary. The density of the green body is preferably at least 80%, in particular between 90% and 96%, of the solid density of the material.

[0062] The green body can then be dewaxed at room temperature and subjected to one-stage, two-stage or multi-stage sintering and then preferably cooled to room temperature. The sintering can be carried out at a temperature between 500°C and 1300°C, for example.

[0063] Since these method sequences and the method parameters used therein are likewise known from the prior art, in order to avoid repetitions, reference is made to the relevant prior art in this regard.

[0064] By sintering, a preform 11 is formed from the green body, as is exemplified in Figure 3The preform 11 can be designed as a flat plate or in a plate-shaped manner, so that at least a section of the first surface 3 and the second surface 5 can extend parallel to each other.

[0065] According to an embodiment variant of the method, it can be provided that the second surface 5 of the preform 11 provided with the cooling structure is produced in a curved manner at least in some sections. In general, the preform 11 can be produced with different thicknesses 12 at least in some sections. In particular, the preform 11 can be produced thinner in at least one edge section 13 or in a plurality of edge sections 13 than in the central section 14, such as in this Figure 3 The central section 14 is the region of the preform 11 with the greatest thickness 12. The thinner edge sections 13 can be formed, for example, around the central section 14, i.e. along the entire periphery of the central section 14. The reduction in thickness 12 can be formed abruptly and / or ramp-shaped starting from the central section 14, as is also the case in Figure 3 Other shapes are also possible.

[0066] The reduced thickness 12 in at least one edge section 13 can also be present on the finished cooling device 1 as a shoulder or a stepped connection groove 25, such as from Figure 2 or from Figure 6 Can be seen.

[0067] Due to the improved formability of the preform 11, other shapes of the second surface 5 of the preform 11 are possible. Thus, a first pin-fin or cooling projection (round, egg-shaped, oval, teardrop-shaped or nipple-shaped, etc.) with a height between 0.1 mm and 2.0 mm can already be preformed on the preform 11. Additionally, structures (waves, ribs, etc.) can be deliberately introduced into the second surface 5 of the preform 11 in order to increase the turbulence of the cooling medium flowing past, if necessary.

[0068] The preform 11 can then be recompacted. However, the recompacting preferably takes place simultaneously with the shaping of the preform 11 into the cooling device 1 with the cooling projections 6.

[0069] The preform 11 is formed in a forming die 15 to realize a cooling structure with a plurality of cooling projections 6. For this purpose, the preform 11 is placed in the forming die 15 or is placed against the forming die. In the simplest case, the forming die 15 comprises a perforated plate 16. The perforated plate 16 has a recess 17, in particular a penetration, into which a part of the material of the preform 11 is pressed or through which the cooling projections 6 are formed. The remaining part of the material of the preform 11 which is not pressed into the recess 17 of the forming die 15 or pressed through the recess of the forming die forms the base section 4 of the cooling device 1.

[0070] The recess 17 , ie its cross section, is adapted accordingly to the cross section of the cooling projection 6 to be produced.

[0071] The shaping die 15 can also have a different appearance, ie need not necessarily be a simple perforated plate 16. The shaping die 15 can be designed in particular as a "pot-shaped" die.

[0072] In the event that at least one further structural element 10 is present, this can also be taken into account by means of a corresponding recess or a corresponding penetration in the shaping die 15 .

[0073] For forming, the punch 18 can be placed against the first surface 3 of the preform 11 and pressed against the preform 11 with a predeterminable pressure, the back side also forming the first surface 3 of the base section 4. The material of the preform 11 is pressed into the recess 17 or penetration of the forming mold 15 by the pressure applied to the preform 11. The forming can be carried out, for example, at a pressure between 700 MPa and 1600 MPa. In addition, the forming can be carried out during a time of up to 10 seconds, in particular between 0.1 seconds and 10 seconds. In addition, the forming is preferably carried out at room temperature (20°C), i.e., cold forming. Alternatively, the forming can also be carried out after the preform 11 is preheated to a temperature between 50°C and 300°C, for example, between 50°C and 150°C and / or in or with the forming mold 15 heated to a temperature between 50°C and 300°C, for example, between 50°C and 150°C.

[0074] It can be provided that the forming of the parison 11 into the cooling structure or into the cooling device 1 is carried out in multiple stages, that is, in two or more steps. For example, the forming method can include two or more forming steps until the cooling projection 6 is formed. In particular, three, four, five, etc. forming steps using the same or staged different forming molds 15 can be provided to produce the cooling projection 6.

[0075] It should be mentioned here that the multi-stage forming refers to the forming of the preform 11 into the cooling projections 6 and not to further forming which may also be carried out, such as, for example, the calibration of the cooling projections 6 , as will be described below.

[0076] The multi-stage forming can be carried out with at least approximately constant forming degrees in the individual forming steps. The cooling projection 6 can, for example, undergo at least approximately the same height change in each of the forming steps. However, it is also possible that the forming degrees in the individual forming steps also differ from one another. The height change of the cooling projection 6 can, for example, be greater in the first forming step than in the subsequent forming steps, or conversely, the height change of the cooling projection 6 can be smaller in the first forming step than in the subsequent forming steps.

[0077] In each molding step, the parameters for molding may be the same or different. The pressure applied to the parison 11 may be greater in the first molding step than in the subsequent molding steps, for example. The parameters for molding in each molding step are selected from the above ranges.

[0078] In the case of a two-stage or multi-stage forming method for forming the cooling projection 6, the cooling projection 6 can be formed with a first sub-height in the first forming step of forming the parison 11 using a forming die 15, for example the perforated plate 16 mentioned above. The first sub-height is smaller than the height 8 of the cooling projection 6 after the second forming step. The first sub-height can be in the range of 20% to 80% of the height 8, for example.

[0079] After the preform 11 has been shaped, ie formed, the cooling device 1 can be completed. However, there is also the possibility of further processing the cooling device 1, in particular of calibrating the cooling device 1, as will be explained below.

[0080] The cooling device 1, which is made of a metal sintered material and produced by powder metallurgy, is then integrally joined to the metal casting 19, as in Figure 5 or Figure 6 Schematically illustrated in FIG. This casting 19 can be a die-casting made of aluminum or an aluminum alloy. The casting 19 can be a housing part, such as a housing part in a drive train, or a part of a support structure, such as a part of a support platform. The material-locked joint between the sintered and formed cooling body 1 and the casting 19 is formed by fusion welding, in particular laser welding, or by brazing. In this way, a multi-piece, integrally joined cooling assembly 20 for the power electronic component 2 is realized.

[0081] The joining process with the cast part 19 can be carried out after the cooling device 1 has been finally manufactured, in particular after final shaping.

[0082] According to Figure 5 In the embodiment of the cooling device 1, the cooling device 1 is connected to the casting 19 by means of its narrow face or side face 21 extending between the first surface 3 and the second surface 5 by means of a weld seam 22 or alternatively by means of a brazing material. The weld seam 22 can be formed by a weld material.

[0083] Preferably, the weld seam 22 is formed only by partial melting of the material of the casting 19 and partial melting of the material of the cooling device 1, i.e. without adding welding material, as in Figure 6 Shown in.

[0084] The casting 19 can define, in particular spatially delimit, a cavity 23 for a cooling medium. The cavity 23 can in particular conduct a circulating cooling medium, such as oil or water, in a defined manner.

[0085] A wall opening 24 can be formed in the casting 19. This wall opening 24 is dimensioned so that it is closed fluid-tightly by the cooling device 1 inserted therein and by the weld 22. The joint between the cooling body 1 and the casting 19 is implemented without additional sealing elements, in particular fluid-tightly only by the weld 22. Correspondingly, the cooling device 1 is welded or brazed to the casting 9 in a sealing manner in order to form the cooling assembly 20. The connection between the sintered and molded cooling device 1 and the casting 19 is implemented in particular without threads and in a sealing manner, thereby making it possible to produce a cooling assembly 20 for high power at low cost.

[0086] The cooling device 1 can be used as in Figure 2 and Figure 6 As shown in the figure by way of example in the figure, the outer circumference of the cooling device 1 has a stepped connection groove 25, in particular a single connection groove, and a so-called shoulder is formed accordingly. The stepped connection groove 25 can be in contact with the delimiting section of the wall penetration 24 of the metal casting 19 in a load-transmitting and heat-conducting manner. In the delimiting section 26 of the wall penetration 24 and in the stepped connection groove 25 of the cooling device 1, contact surfaces 27, 28 can be formed which are parallel to each other and which are in contact in the joined state of the cooling device 1 and the casting 19.

[0087] The delimiting section 26 around the wall penetration 24 can be machined, for example face milled, in order to form a contact surface 27 for the cooling device 1 with sufficient flatness. This allows a good heat transfer between the cooling device 1 and the casting 19 and a reliable seal at the welding or brazing point. The machining of the casting 19 can be carried out as in Figure 6 As can be seen in FIG. 2 , a shoulder or a stepped groove is formed or else a tapering, non-stepped contact surface 27 is designed.

[0088] The weld seam 22, which is preferably implemented circumferentially and without interruption around the cooling device 1 or along the wall penetration 24, can be produced by a laser beam welding device 29. The weld seam 22 can be implemented as a fillet weld 30 between the circumferential side surface 21 of the cooling device 1 and the contact surface 27 on the casting 19. This allows process-stable and time-optimized production and reliable sealing without the need for separate sealing elements.

[0089] The casting 19 can be an aluminum die casting, and the sintered material of the cooling device 1 can consist mainly of aluminum or mainly of copper. The proportion of pure aluminum or pure copper in the cooling device 1 can be particularly high by implementing the component produced by powder metallurgy, in particular 97.5% by volume of aluminum or 99% by volume of copper of all materials present in the cooling device 1. Due to the high metal purity of the sintered and pressed cooling device 1, in particular with regard to its aluminum or copper content, a relatively high thermal conductivity or a higher cooling power of the cooling device 1 produced by powder metallurgy can be achieved compared to a cooling body produced by extrusion or casting.

[0090] The end section of the cooling projection 6 facing away from the base section 4 can protrude into the cavity 23 of the metal casting 19 so that it can be surrounded by the cooling medium in the cavity 23. A power electronic component 2 can be fixed on the first surface 3 of the contact section 4 facing away from the cooling projection 6, which is thus separated from the cavity in a liquid-tight manner but is in thermal connection with the cooling medium.

[0091] As in Figure 7 As illustrated in the figure, it can be provided that: by at least one forming die 15 ( Figure 4 ) After shaping, that is, after the preform 11 has been formed, the cooling device 1 is calibrated. By means of the calibration, the dimensional accuracy of the cooling device 1 is improved at least in some sections or locally. In addition, by means of the calibration, pores in the area of ​​the calibrated surface can be closed, thereby making it possible to achieve a denser structure. During the calibration, the cooling structure, in particular at least individual cooling projections of the cooling projections 6, are subjected to pressure on the corresponding surface.

[0092] According to a preferred embodiment variant, the height of the cooling projection 6 can be calibrated, as in Figure 6 . Here, a calibration die 31, which can be designed, for example, in the form of a plate or a punch, can be pressed from above onto the cooling projection head 7. During this process, the cooling device 1 can be held in a holding element, for example a die. The height deviation after a plurality of forming steps can be reduced, for example, in the direction of the central section 14 of the cooling device 1 (see Figure 3 ), until the height difference of the cooling projection 6 or the tolerable tolerance range of the height 8 is reached. Unless part of this height difference has already been taken into account by the shape of the preform 11 (for example, by forming areas with different thicknesses 12, for example according to a curve), the calibration can be carried out accordingly. With a preform 11, which has already at least partially taken into account the height deviations of the sintered and formed green body, the calibration work, i.e. the calibration expenditure, can be reduced.

[0093] The calibration tool 22 can also have a mold cavity in which the cooling projections 6 are at least partially accommodated during calibration.

[0094] The calibration can be carried out in one stage or in several stages, if necessary with an intermediate depressurization of the cooling device 1 between the calibration steps.

[0095] According to one embodiment variant, it can also be provided that the height 8 of the cooling projection 6 is adjusted by pressing material from the head region of the cooling projection 6 (cooling projection head 7) into the region 32 next to or below the head region of the cooling projection 6. Figure 7 For the extrusion, a simple plate-shaped die, in particular the aforementioned calibration die 31 , can be used which is pressed onto the cooling projection 6 .

[0096] It may be advantageous for the calibration or the extruded material that the height difference of the cooling projection 6 after the forming is between a maximum of 0.2 mm and a maximum of 0.4 mm, i.e., it is produced with relatively small height differences. This can be achieved, for example, by taking into account the shape of the preform 11 as described above. The final height tolerance can be achieved relatively easily in a subsequent work process by means of height calibration.

[0097] With this calibration, machining of the cooling projections 6 in order to reduce the height tolerance of the cooling projections 6 can be avoided. By reducing the height tolerance, partially mushroom-shaped or (slightly) convex cooling projections 6 can be produced, which can also be advantageous with regard to the flow of the coolant flowing around the cooling projections 6 and thus with regard to the cooling capacity of the cooling device 1. Furthermore, reducing the height tolerance can also reduce or eliminate residual porosity at the upper end of the cooling projections 6.

[0098] As described above, the cooling projections 6 of the cooling device 1 can also have different heights 8. In order to be able to carry out a height calibration in this case as well, the calibration mold 31 can be designed according to the desired height profile of the cooling projections 6, for example in stages.

[0099] A correspondingly designed calibration mold 31 can also be used to form a specific shape of the cooling projection 6. For this purpose, the calibration mold 31 can have a matching contour, for example, so that the head of the cooling projection 6 is correspondingly shaped, that is, provided with a contour or surface design such as, for example, a rounding, a chamfer, etc. or with a recess, a surface roughness greater than the roughness after sintering, etc.

[0100] In the case of a configuration with cooling projections 6 of different heights, a staged calibration mold 31 can also be used.

[0101] The method can be used to manufacture a cooling device 1 for cooling a component 2, the cooling device having a cooling structure having a base section 4 with a first surface 3 and cooling projections 6, the cooling structure protruding from a second surface 5 on the base section 4. At least some of the cooling projections 6 can have a higher density in the head region than the remaining cooling projections 6, and / or at least some of the cooling projections 6 can have a different shape in the head region than the remaining cooling projections 6.

[0102] The various embodiments illustrate possible implementation variants, wherein it should be noted here that the present invention is not limited to its specifically illustrated implementation variants, but rather, different combinations of the individual implementation variants with one another are possible and these variant possibilities fall within the capabilities of a person skilled in the art based on the technical processing teachings through the present invention.

[0103] The scope of protection is determined by the claims. However, the description and the drawings are to be taken into account for the interpretation of the claims. Individual features or combinations of features in the different embodiments shown and described can themselves be independent inventive solutions. Tasks based on independent inventive solutions can be derived from the description.

[0104] Finally, it should be pointed out that, in order to provide a better understanding of the construction, some elements are shown not to scale and / or enlarged and / or reduced in size.

[0105] Reference numerals list

[0106] 1Cooling equipment

[0107] 2 Components (electrical and electronic)

[0108] 3. First surface

[0109] 4 Basic sections

[0110] 5 Second surface

[0111] 6 Cooling protrusion

[0112] 7 Cooling protrusion head

[0113] 8 Height

[0114] 9 recesses

[0115] 10 Structural elements

[0116] 11 parison

[0117] 12thickness

[0118] 13 Edge Segment

[0119] 14 Middle section

[0120] 15 Forming die

[0121] 16-well plate

[0122] 17 Gap

[0123] 18 Die

[0124] 19 Castings

[0125] 20 Cooling components

[0126] 21 Side

[0127] 22 welds

[0128] 23 Cavity

[0129] 24 Wall penetration

[0130] 25-step interface slot

[0131] 26 Define the section

[0132] 27 contact surface

[0133] 28 facing surface

[0134] 29Laser beam welding equipment

[0135] 30 fillet weld

[0136] 31 Calibration tools

[0137] 32 areas.

Claims

1. A method for producing a cooling assembly (20) for a power electronic component (2), the method comprising the following steps: - Providing a powder metallurgical material and forming or pressing the material into a green body; - sintering the green body into a body (11); - forming the preform (11) into a cooling device (1) having a cooling structure with an enlarged surface, the cooling structure comprising a plurality of cooling projections (6), the cooling projections (6) being formed by means of a forming die (15) which can be loaded with pressure, in that a partial section of the preform (11) is pressed into a shaped recess (17) of the forming die (15) and a base section (4) is left, the base section (4) connecting the individual cooling projections (6); and The cooling device (1) is integrally joined to the metal casting (19) by welding, in particular laser welding or soldering.

2. The method according to claim 1, characterized in that The cooling projection (6) is formed into a cylindrical or conical shape by means of a recess (7) in the forming die (15).

3. The method according to claim 1 or 2, characterized in that: A cavity (23) for a cooling medium is defined or at least partially delimited by the metal casting (19), the cooling device (1) is inserted into a wall penetration (24) of the metal casting (19), and the wall penetration (24) is closed liquid-tightly by the cooling device (1) without a separate sealing element.

4. The method according to any one of the preceding claims, characterized in that The cooling device (1) has a stepped connection groove (25) on its outer circumference which is produced by forming with the forming die (15) or another forming die and which is used to abut against a delimiting section (26) of a wall penetration (24) of the metal casting (19).

5. The method according to claim 4, characterized in that Prior to the integrally bonded joining to the cooling device (1), a delimiting section (26) of the wall aperture (24) is machined so that a flat contact surface (27) is achieved for the cooling device (1).

6. The method according to any one of the preceding claims, characterized in that An end section of the cooling projection (6) facing away from the base section (4) projects into a cavity (23) of the metal casting (19) and fixes the power electronic component (2) on a first surface (3) of the base section (4) facing away from the cooling projection (6).

7. The method according to any one of the preceding claims, characterized in that A laser beam welding device (29) is used for the integrally bonded joining, by means of which a fillet weld (30) is formed between a circumferential side surface (21) of the cooling device (1) and the cast part (19).

8. The method according to any one of the preceding claims, characterized in that The shaping of the preform (11) into the cooling device (1) is carried out in a plurality of shaping steps.

9. A cooling assembly (20) for cooling a power electronic component (2), the cooling assembly comprising a cooling device (1) as a mounting platform for at least one power electronic component (2), the cooling device (1) being further fixed to a metal component, the cooling device (1) having a first surface (3) on its base section (4) for mounting the at least one power electronic component (2), and a second surface (5) of the base section (4) opposite to the first surface (3) being provided with a cooling structure comprising a cooling protrusion (6), It is characterized in that The base section (4) and the cooling projection (6) are composed of sintered material, the cooling projection (6) is manufactured from the material of the base section (4) by molding, the metal component is a casting (19), and the base section (4) of the cooling device (1) is joined to the metal casting (19) by welding, in particular laser welding, or by brazing in a material-locking manner, and a fluid-tight connection between the cooling device (1) and the casting (19) is simultaneously established by the material-locking joint.

10. The cooling assembly (20) according to claim 9, characterized in that The cooling projection (6) on the second surface (5) of the base section (4) is designed to be cylindrical or conical.

11. The cooling assembly (20) according to claim 9 or 10, characterized in that: The metal casting (19) defines or at least partially delimits a cavity (23) for a cooling medium, the cooling device (1) is inserted into a wall penetration (24) of the metal casting (19), and the wall penetration (24) is closed liquid-tightly by the cooling device (1) without a separate sealing element.

12. The cooling assembly (20) according to any one of claims 9 to 11, characterized in that: The cooling device (1) has a stepped connection groove (25) on its outer circumference, which bears against a delimiting section (26) of a wall penetration (24) of the metal casting (19) in a load-transmitting and heat-conducting manner.

13. The cooling assembly (20) according to any one of claims 9 to 12, characterized in that: The casting (19) is an aluminum die casting, and the sintered material of the cooling device (1) consists mainly of aluminum or mainly of copper.

14. The cooling assembly (20) according to any one of claims 9 to 13, characterized in that At least some of the cooling protrusions (6) have a higher density than the remaining cooling protrusions (6) in their head section facing away from the base section (4), and / or at least some of the cooling protrusions (6) have a different shape from the remaining cooling protrusions (6) in the head section.

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