Method for producing a cooling arrangement

Abstract

Method for producing a cooling arrangement (KA) for cooling a power electronics device (LV), comprising the following steps: - Providing a carrier (TR) for supporting and cooling the power electronics device (LV); - forming, punching or cutting a sheet metal part (BL) into a cooling structure (KS) with a connecting section (VA) and a plurality of cooling structure elements (KE), wherein the cooling structure elements (KE) are formed, punched or cut in one piece transversely to the connecting section (VA) and with the connecting section (VA) when viewed in a longitudinal direction (LR) of the connecting section (VA); - First bending of the cooling structure elements (KE) so that the cooling structure elements (KE) extend away from the connecting section (VA) and obliquely or perpendicularly to the connecting section (VA); - welding the connecting section (VA) to the support (TR) in such a way that the cooling structure (KS) is physically and thermally connected to the support (TR); - Second bending of the cooling structure elements (KE) so that at least two cooling structure elements (KE) adjacent to each other in the longitudinal direction (LR) extend in different directions.

Description

Technical Field:The present invention relates to a method for manufacturing a cooling arrangement.STATE OF THE ART AND OBJECT OF THE INVENTIONCooling arrangements for cooling power electronics devices are known. In this case, the cooling arrangements often also serve, in addition to the cooling, as circuit carriers for carrying the power electronics devices or their power electronics arrangements.EP 1 328 020 A1 describes a cooling fin structure with cooling fins for a heat sink, which is produced by punching and bending. In this case, the cooling fin structure together with the cooling fins is bonded to a heat absorption plate with the aid of a thermally conductive adhesive or riveted by means of rivets.The publication US 2004 / 0 244 959 A1 describes cooling ribs which are welded onto a substrate.U.S. Pat. No. 5,518,071 A describes a cooling device having a cooling structure which has fin-like alternately angled cooling ribs. The cooling structure is mounted on a base plate.The publication DE 20 2004 009 244 U1 describes a cooling body having a foundation made of copper and having a covering layer made of aluminum, which is in contact with the upper side of the foundation, wherein the covering layer has a multiplicity of lamellae which are worked out from the surface of the covering layer by means of a skinning method.The publication DE 10 2004 058 806 A1 describes a method for producing circuit structures on a heat sink, wherein at least one specifically structured, electrically insulating layer and at least one specifically structured, electrically conductive layer are formed additively directly on the heat sink.The publication DE 102 17 214 A1 describes a circuit arrangement comprising a circuit carrier with a heat-generating electronic component and cooling means, to which the circuit carrier is connected in a heat-conducting manner. The circuit arrangement further comprises a thermally conductive layer covering a surface of the circuit carrier such that a thermally conductive connection is thereby established between the circuit carrier and the cooling means.The document DE 10 2015 224 961 A1 describes a circuit component with a circuit carrier, an electronic component, a cladding and a metallic layer on the cladding, which is provided with a corrosion protection layer.There is the general requirement here to produce the power electronics devices and thus also the cooling arrangements at low cost.The object of the invention is thus to produce a cooling arrangement at low cost.DESCRIPTION OF THE INVENTIONThis object is achieved by a method for manufacturing a cooling arrangement according to claim 1. Advantageous embodiments are the subject matter of the dependent claims.According to the invention, a method of manufacturing a cooling arrangement for cooling a power electronic device is provided.According to the method, a carrier for supporting and cooling the power electronic device is provided.Furthermore, a sheet metal part is formed, stamped or cut into a cooling structure having a connecting section and a plurality of cooling structure elements. In this case, the cooling structure elements are formed, stamped or cut in one piece with the connecting section, as viewed in a longitudinal direction of the connecting section transversely with respect to the connecting section and with the connecting section.After this, the cooling structural elements are bent in a first bending process such that the cooling structural elements extend away from the connecting section and obliquely or perpendicularly to the connecting section.Subsequently, the connecting portion is welded, in particular roll seam welded or laser beam welded, to the carrier in such a way that the cooling structure is physically and thermally connected to the carrier.Furthermore, in a second bending process, the cooling structure elements are bent further in such a way that at least two cooling structure elements adjacent to one another in the longitudinal direction extend in different directions.The cooling structure elements are formed by cuts (for example by separating, such as cutting or punching) that are applied transversely to the connecting section as viewed in the longitudinal direction and extend away from the connecting section and obliquely or perpendicularly to the connecting section.Because the cooling structure is welded (directly) onto the carrier, connecting means which are otherwise required and which require additional production costs and additional production outlay are dispensed with. In addition, the welding per se is substantially simpler and more cost-effective compared to other production methods, such as metal powder injection molding.Moreover, the cooling arrangement has a good thermal conductivity thanks to the stable and (direct) connection between the cooling structure and the carrier.The cuts, by which the cooling structure elements are formed, can also be made with simple tools by simple separation, such as cutting or punching.The cooling structure elements, which are formed by the cuts transversely to the connecting portion and extend away from the connecting portion and obliquely or perpendicularly to the connecting portion, can generate vortices in a cooling medium flowing past the cooling structure elements, which in turn increases the cooling efficiency.This provides a possibility of producing a cooling arrangement cost-effectively, which is additionally efficient.The cooling arrangement produced in this way can also be applied to an existing power electronics substrate (i.e. a circuit carrier). In this case, the cooling arrangement can be welded onto the power electronics substrate, in particular if the power electronics substrate has a metal layer (for forming a welded connection) on its corresponding surface.For example, the cooling structure elements are formed by separating, in particular by punching or cutting. In the separating process, the aforementioned cuts are made transversely to the connecting portion.For example, the cooling structure elements are further bent further in the second bending process in such a way that at least two cooling structure elements lying opposite one another when viewed transversely to the longitudinal direction (and thus with respect to the connecting portion) extend in the same direction.For example, a protective layer for protecting the carrier from corrosion is arranged between the carrier and the cooling structure, which protective layer is physically and thermally connected to the carrier and the cooling structure and serves for protecting the carrier from corrosion.For example, the protective layer is spray-coated on the carrier, or galvanically coated or rolled on.For example, the connecting section is welded on a surface of the protective layer facing away from the carrier.For example, the carrier is made of a first metal or a first metal alloy, especially. Copper or a copper alloy is prepared. The protective layer is produced, for example, from a second metal or a second metal alloy, in particular from aluminum or an aluminum alloy.For example, the cooling structure elements are formed integrally with the connecting portion.For example, the connecting portion and the cooling structure elements are formed, stamped or cut from a sheet of a third metal or a third metal alloy, in particular from aluminum or an aluminum alloy.Brief Description of the Drawings:Exemplary embodiments of the invention are explained in more detail below with reference to the attached drawings. The following are shown: FIG. 1 is a schematic illustration of a cross section of a power electronic device with a cooling arrangement, produced according to an exemplary embodiment of the invention; and FIGS. 2A, 2B, 2C, 2D each show, in a schematic oblique view illustration, the power electronics device illustrated in FIG. 1 with the cooling arrangement in its four production stages according to a method according to an exemplary embodiment of the invention.Detailed Description of the Drawings:The power electronics device LV in FIG. 1 comprises a power electronics arrangement LA in the form of an electrical circuit with corresponding circuit components and a cooling arrangement KA for carrying and cooling the power electronics arrangement LA.The cooling arrangement KA comprises a carrier TR for carrying and cooling the power electronics arrangement LA. The power electronics arrangement LA is arranged on a first surface OF 1 of the carrier TR and is physically and thermally connected to the carrier TR, and is electrically insulated from the carrier TR by means of an insulating layer IS between the power electronics arrangement LA and the carrier TR.The carrier TR is made of a copper alloy in this embodiment.The cooling arrangement KA further comprises a protective layer SS which is formed on a second surface OF 1 of the carrier TR facing away from the first surface OF 1 by spray coating or galvanic coating and is physically and thermally connected to the carrier TR. The protective layer SS is made of an aluminum alloy and protects the carrier TR from corrosion by cooling medium.The cooling arrangement KA further comprises a plurality of cooling structures KS which are arranged on a surface OF 3 of the protective layer SS facing away from the carrier TR and are physically and thermally connected to the protective layer SS and thus to the carrier TR. In this case, the cooling structures KS are welded on the protective layer SS. The cooling structures KS each consist of a correspondingly shaped sheet metal part made of a further aluminum alloy and each comprises a connecting section VA and a plurality of cooling structure elements KE formed integrally with the connecting section VA. In this case, the connecting portions VA of the respective cooling structures KS are welded on the protective layer SS and extend in a longitudinal direction LR of the cooling arrangement KA (compare with FIG. 2D ). The cooling structure elements KE are formed by cuts ES which are stamped in transversely with respect to the connecting portion VA of the respective corresponding cooling structures KS, as viewed in the longitudinal direction LR, and are bent with respect to the connecting portion VA, such that they extend away from the connecting portion VA and obliquely with respect to the connecting portion VA. In this case, two cooling structure elements KE of the respective cooling structures KS adjacent to one another in the longitudinal direction LR extend in different directions, in particular perpendicular to one another. Furthermore, two cooling structure elements KE opposite each other with respect to the connecting portion VA of the respective corresponding cooling structures KS extend in the same direction.The cooling structure elements KE extending in opposite directions as described above generate vortices in a cooling medium flowing past the cooling structure elements KE and thus increase the cooling effect of the cooling arrangement KA.After the power electronic device LV has been described in detail with reference to FIG. 1, a method for producing the cooling arrangement KA is described in more detail below with the aid of FIGS. 2A, 2B, 2C and 2D :According to the production method, a carrier TR made of a copper alloy is provided, which has a flat surface OF 1, OF 2 on two opposite sides in each case.On a first of the two surfaces OF 1 of the carrier TR, an insulating layer IS is applied by spray coating, which will later serve for electrical insulation between the electrically conductive carrier TR and a power electronics arrangement LA on the carrier TR.On a second surface OF 2 of the carrier TR facing away from the first surface OF 1, a protective layer SS made of an aluminum alloy is applied by spray coating or galvanic coating. The protective layer SS serves to protect the carrier TR from, for example, corrosion by the cooling medium.Furthermore, cooling structures KS are formed from longitudinally shaped sheet metal strips BL (sheet metal part) made of a further aluminum alloy, wherein by applying cuts ES to both side regions of the respective cooling structures KS, a connecting section VA in each case is cut or formed in the middle region of the respective cooling structures KS and a plurality of cooling structure elements KE in each case is cut or formed on both side regions of the corresponding cooling structures KS. Thereby, cooling structures KS are formed each having a connecting portion VA in the central region and a plurality of the cooling structure elements KE on both sides of the connecting portion VA, wherein the cooling structure elements KE are formed transversely to the connecting portion VA as viewed in the longitudinal direction LR of the cooling structures KS and extend away from the connecting portion VA, as illustrated in FIG. 2A.Subsequently, in each sheet metal strip BL, the cooling structure elements KE are pre-bent relative to the connecting portion VA in a first bending process, as a result of which the cooling structure elements KE extend almost perpendicularly to the respective corresponding connecting portion VA, as is illustrated in FIG. 2B.Thereafter, the connecting sections VA of the sheet metal strips BL with the pre-bent cooling structure elements KE are welded in a welding process, for example by roll seam welding or laser beam welding, on a surface OF 3 of the protective layer SS facing away from the carrier TR, whereby the connecting sections VA of the respective sheet metal strips BL are physically and thermally connected to the carrier TR, as is illustrated in FIG. 2C.Subsequently, the cooling structure elements KE of all sheet metal strips BL are finally bent in a second bending process in such a way that in each case two cooling structure elements KE of each sheet metal strip BL adjacent to one another in the longitudinal direction LR extend virtually perpendicularly to one another and therefore in different directions, and in each case two cooling structure elements KE lying opposite one another viewed transversely to the longitudinal direction LR and thus viewed with respect to the respective corresponding connecting portion VA extend virtually parallel to one another and thus in the same direction, as is illustrated in FIG. 2D. As a result, cooling structures KS are formed with the cooling structure elements KE bent in opposite directions.A cooling arrangement KA is thus produced with a carrier TR and cooling structures KS arranged on the carrier TR, wherein the cooling structures KS generate vortices in the cooling medium, such as cooling water, flowing past the cooling structures KS by the cooling structure elements KE shaped as described above. The turbulence positively acts on heat absorption by the cooling medium and thus increases the cooling capacity of the cooling arrangement KA.Such a cooling arrangement KA also has the following advantages:Thanks to the protective layer SS between the carrier TR and the cooling structures KS, which seals the carrier TR with respect to the coolant, the cooling arrangement KA has no or hardly any corrosion despite the difference in the metals used for the carrier TR and the cooling structures KS.Because the protective layer SS is applied by spray coating or electroplating, it can be made very thin. This is advantageous for efficient heat transfer.The carrier TR can be realized with a copper alloy in a high plate thickness. This increases the heat capacity of the structure. The carrier TR can thus counteract temperature fluctuations in the power electronics arrangement LA.The welded connection between the carrier TR and the cooling structures KS is substantially more stable and maintenance-free compared to other types of connection, such as a soft solder connection or a screw connection.The cooling arrangement KA can be produced comparatively inexpensively, since only simple production steps, such as welding, bending, are used and no expensive and complicated steps, such as metal powder injection molding, are required.Such a cooling arrangement KA can be manufactured in various sizes (no size limitation).The production of the cooling arrangement KA can also take place at room temperature, since no distortion between the carrier TR and the cooling structures KS as a result of temperature fluctuations is to be expected.All of the advantages listed are achieved through the use of the welding process. In some cases, the welding process requires linear welding. This is realized by the bending process divided into two bending steps with a later bending step after the welding process.The cooling arrangement KA has good heat conduction and heat spreading, which frequently occur, in particular, for local or punctiform heat sources, such as, for example, in converters.

Claims

Method for producing a cooling arrangement (KA) for cooling a power electronics device (LV), having the following steps: - providing a carrier (TR) for carrying and for cooling the power electronics device (LV); - forming, punching or cutting a sheet metal part (BL) to form a cooling structure (KS) having a connecting section (VA) and a plurality of cooling structure elements (KE), wherein the cooling structure elements (KE) are formed, punched or cut in one piece, as viewed in a longitudinal direction (LR) of the connecting section (VA), transversely with respect to the connecting section (VA) and with the connecting section (VA); first bending of the cooling structure elements (KE) such that the cooling structure elements (KE) extend away from the connecting portion (VA) and obliquely or perpendicularly to the connecting portion (VA); welding of the connecting portion (VA) to the carrier (TR) such that the cooling structure (KS) is physically and thermally connected to the carrier (TR); second bending of the cooling structure elements (KE) such that at least two cooling structure elements (KE) adjacent to one another in the longitudinal direction (LR) extend in different directions.Method according to claim 1, wherein the step of second bending provides that the cooling structure elements (KE) are bent such that at least two cooling structure elements (KE) lying opposite one another when viewed transversely to the longitudinal direction (LR) extend in a same direction.Method according to claim 1 or 2, further comprising the steps of: - arranging a protective layer (SS) for protecting the carrier (TR) from corrosion between the carrier (TR) and the cooling structure (KS); - physically and thermally connecting the protective layer (SS) to the carrier (TR) and the cooling structure (KS).Method according to claim 3, wherein the steps of arranging and connecting the protective layer (SS) further provide that the protective layer (SS) is spray coated, or electroplated, or rolled on the carrier (TR).Method according to Claim 3 or 4, wherein the connecting section (VA) is welded to a surface (OF2) of the protective layer (SS) facing away from the carrier (TR).Method according to one of Claims 3 to 5, wherein - the carrier (TR) is made from a first metal or a first metal alloy, in particular. Copper or a copper alloy; and - the protective layer (SS) is made of a second metal or a second metal alloy, in particular of aluminum or an aluminum alloy.Method according to one of the preceding claims, wherein the cooling structure elements (KE) are formed integrally with the connecting portion (VA).Method according to claim 7, wherein the connecting portion (VA) and the cooling structure elements (KE) are formed, stamped or cut from a sheet of a third metal or a third metal alloy, in particular from aluminium or an aluminium alloy.Method according to one of the preceding claims, wherein the welding step further provides that the connecting portion (VA) is welded to the carrier (TR) by means of roll seam welding or laser beam welding.

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