Cooler arrangement and method for producing same

Abstract

The present invention relates to a cooler arrangement of electronic power elements (4), comprising a cooler housing (10), in which at least one continuous recess (13) is located, the cooler housing defining a cooling channel (16), and the cooler housing (10) being made of stainless steel, and at least one copper heat sink (2) which is located in the recess (13) of the cooler housing (10), a fluid-tight connection being formed between the heat sink (2) and the cooler housing (10).

Description

[0001] Description

[0002] title

[0003] Cooler arrangement and method for its manufacture

[0004] State of the art

[0005] The present invention relates to a cooler arrangement for power electronics and a method for manufacturing the cooler arrangement.

[0006] Power semiconductors in power electronics carry high electrical currents. Together with switching losses, the resulting conduction losses are responsible for high heat dissipation, which must be dissipated from a very small area. The maximum permissible semiconductor temperature is critical for failure, which is why minimizing the thermal resistance between the semiconductor and the coolant is of central importance. For efficient cooling, the power substrates are applied to fluid-flowable heat sinks. To achieve low thermal resistance between a power substrate, especially an AMB / DBC power substrate (AMB: active metal braze; DBC: direct copper bonding), and the heat sink, the power substrate is bonded to the heat sink using a soft soldering process, or optionally a sintering process.In automotive engineering, aluminum coolers, also known as AlSiC or copper coolers, are commonly used. These coolers consist of several components joined primarily by brazing. The same material is typically used for the entire cooler assembly. Inside the cooler, pins or fins are arranged to increase the heat-transferring surface area and enhance heat transfer. Such a cooler assembly with a periodically repeating wave profile is known from DE10 2021 211544 A1.

[0007] Disclosure of the Invention: The cooling arrangement for power electronics according to the invention, comprising the features of claim 1, has the advantage that the cooling arrangement can be optimally designed for the heat dissipation of the power electronics, since two different materials are used for the cooling arrangement. Despite this, the cooling arrangement has a simple and cost-effective design. The cooling arrangement comprises a copper heat sink, which ensures optimal heat transfer and can dissipate heat to a fluid-flowing cooling channel. This is achieved according to the invention by the cooling arrangement having a stainless steel cooling housing and a copper heat sink. The cooling housing has a continuous recess in which the copper heat sink is arranged.The cooler housing defines a cooling channel, wherein the heat sink is fixed to the cooler housing by means of a fluid-tight, in particular a metallurgical, connection, especially a brazed or welded joint. The heat sink thus covers the recess and forms a section of the cooling channel, whereby the heat sink can come into contact with the fluid flowing through the cooling channel.

[0008] Stainless steel is a particularly corrosion-resistant steel, especially with chromium additives. Stainless steel and copper can be thermally joined to form a strong, fluid-tight bond.

[0009] The dependent claims describe preferred embodiments of the invention.

[0010] The stainless steel cooler housing preferably comprises a base and a lid. The base and lid are connected to each other by means of a fluid-tight, in particular a metallurgical, connection, especially a brazed or welded joint. The copper heat sink is formed in one piece. Alternatively, a dedicated heat sink is used for each power electronic component.

[0011] The cooler housing preferably comprises an inlet and an outlet, both also made of stainless steel. The inlet and outlet are fluid-tightly connected to the cooler housing. This fluid-tight connection is preferably a weld or, more preferably, a brazed connection, in particular a hard solder joint. Hard solder is a solder with a brazing temperature above 450 degrees Celsius.

[0012] The copper heat sink preferably features turbulator structures, in particular fins or the like, which project into the cooling channel when assembled. For particularly cost-effective manufacturing, the heat sink is designed in two parts: a stamped base plate and turbulator structures as stamped and bent parts, in particular periodic, wave-like fins in the flow direction, a strip-fin component, or straight fin structures in the flow direction. The two-part heat sink is preferably joined by welding or brazing. Alternatively, the copper heat sink is manufactured as a single piece, either as an extrusion or forging part, in particular as a pin-fin component.

[0013] For particularly cost-effective manufacturing, the base body and / or the lid of the cooler housing are deep-drawn or stamped components. The base body is preferably a trough-shaped deep-drawn component and the lid a stamped component.

[0014] To enable secure and easy attachment of power electronics to the cooling assembly, the heat sink preferably has a mounting surface for the power electronics. This mounting surface is preferably the side of the heat sink facing away from the cooling channel. A substrate for the power electronics is preferably bonded to the mounting surface using a soft solder or sintered layer.

[0015] According to a preferred embodiment of the invention, the copper heat sink has a passivating layer, in particular a nickel-containing layer, on all areas facing the cooling channel. Thus, the cooling fluid flowing through the cooling channel of the cooler assembly comes into contact only with the passivating layer or stainless steel components. Alternatively, the stainless steel components in the cooling channel are also coated. The passivating layer is preferably a coating that is applied galvanically or chemically, or mechanically, for example by roll cladding. This ensures that the cooling fluid does not come into contact with copper, thereby preventing corrosive mechanisms in the cooling system.

[0016] To simplify the coating process, the heat sink is preferably completely covered with a nickel-containing layer. A brazed connection to the heat sink housing is also preferably provided.

[0017] The solder joint is preferably produced using a copper-bronze solder, a silver-based solder, or a nickel-based solder. Alternatively, the passivating layer also serves as the solder for the hard solder joint, thus eliminating the need for additional solder application.

[0018] Preferably, the heat sink has a circumferential rim with which it rests on the cooler housing at its outer surface. A first metallurgical connection, in particular a brazed joint or a welded joint, is formed between the rim and the cooler housing. The heat sink further preferably has cooling elements projecting into the cooling channel, and preferably a second metallurgical connection, in particular a brazed joint or a welded joint, is formed between the cooling elements and a side of the base body facing the cooling channel.

[0019] Preferably, all metallurgical connections of the cooler assembly are created using a common brazing alloy. Alternatively, the metallurgical connections are created wholly or partially by means of a welding process.

[0020] The heat sink is preferably designed in two parts, comprising a base plate and a separate stamped and bent part as a cooling element, in particular a periodic wave-shaped fin or a strip-fin component. Alternatively, the heat sink is designed as a single piece, with the cooling structures being formed, for example, by extrusion or forging.

[0021] Furthermore, the present invention relates to a method for manufacturing a heat sink for power electronics, wherein the method comprises the following steps: - providing a heat sink housing made of stainless steel, wherein at least one recess is formed in the heat sink housing and wherein the heat sink housing defines a cooling channel,

[0022] - Arranging a copper heat sink in the recess of the cooler housing such that the heat sink closes the recess, wherein the heat sink preferably has a rim which preferably rests on an outer surface of the cooler housing and cooling elements protrude through the recess into the cooling channel, and

[0023] - Material-bonded joining, in particular brazing or welding of the heat sink to the cooler housing, to seal the cooling channel fluid-tight.

[0024] The cooler housing is preferably designed in two parts, consisting of a base body and a cover. The base body is connected to the cover by a material-bonded connection, in particular a soldered or welded joint, which is preferably made simultaneously with the fixing of the heat sink to the cooler housing. The soldered joint is preferably a hard solder joint.

[0025] In the inventive method, it is further preferred that all parts of the copper heat sink which lie freely in the cooling channel when assembled are covered with a nickel-containing layer. This prevents corrosion and allows for a wide selection of coolants.

[0026] Drawings

[0027] Preferred embodiments of the invention are described in detail below with reference to the accompanying drawings. The drawing shows:

[0028] Figure 1 is a schematic, perspective view of a

[0029] Cooling arrangement with power electronic elements according to a first preferred embodiment of the invention, Figure 2 a schematic, perspective view of a

[0030] Cooler arrangement according to a first preferred embodiment of the invention,

[0031] Figure 3 shows a schematic sectional view of the cooler arrangement of

[0032] Figure 1 ,

[0033] Figure 4 is a schematic partial sectional view of the cooler arrangement of

[0034] Figure 1 ,

[0035] Figure 5 shows a schematic partial sectional view for a second

[0036] Exemplary embodiment of the invention,

[0037] Figure 6 shows a schematic representation of heat sinks for the second

[0038] Exemplary embodiment of the invention,

[0039] Figure 7 shows a schematic representation of a cooler housing.

[0040] Cooling arrangement without heat sink for the second embodiment of the invention,

[0041] Figure 8 shows a schematic partial sectional view of a heat sink in a

[0042] Cooler arrangement according to a third embodiment of the invention,

[0043] Figure 9 shows a schematic partial sectional view of a heat sink in a

[0044] Cooler arrangement according to a fourth embodiment of the invention,

[0045] Figure 10 shows a schematic partial sectional view of a heat sink in a cooler arrangement according to a fifth embodiment of the invention.

[0046] Figure 11 is a schematic partial sectional view of a heat sink of a

[0047] Cooler arrangement according to a sixth embodiment of the invention, and

[0048] Preferred embodiments of the invention A cooler arrangement 1 according to a first preferred embodiment of the invention is described in detail below with reference to Figures 1 to 4.

[0049] As can be seen in detail from Figures 1 to 4, the cooler arrangement 1 comprises a cooler housing 10 made of stainless steel and a heat sink 2 made of copper for power electronic elements 4.

[0050] The cooler housing 10 is made of stainless steel. As can be seen particularly from Figures 2, 3 and 4, the cooler housing 10 is made of two parts, consisting of a base body 11 and a cover 12.

[0051] The lid 12 is a stamped component and the base body 11 is a deep-drawn stamped component.

[0052] As can be seen from Figure 3, a recess 13 is provided in the lid 12, which is formed as a through opening in the lid 12.

[0053] The cooler housing 10 further includes an inlet port 14 and an outlet port 15. The inlet port 14 and the outlet port 15 are also made of stainless steel.

[0054] The cover 12 and the base body 11 are connected to each other by means of a material-bonded connection 3, in particular a welded or brazed joint. The inlet nozzle 14 and the outlet nozzle 15 are also connected to the base body 11 by means of a material-bonded connection 3 (compare Figures 2, 3 and 4).

[0055] As can be seen particularly from Figures 1, 3 and 4, a heat sink 2 is provided, which is made entirely of copper. The heat sink 2 is arranged in the continuous recess 13 in the cover 12 of the cooler housing 10.

[0056] As can be seen from Figures 3 and 4, the heat sink 2 has a base plate 20 and projecting turbulator structures 21. Turbulator structures are cooling elements that can be designed as wave-shaped rib structures, strip fins, straight rib structures, or as pin fins by means of extrusion or forging. The cooler housing 10 forms a cooling channel 16, with the projecting turbulator structures 21 extending into the cooling channel 16 (compare Figures 3 and 4).

[0057] The heat sink 2 further has a circumferential rim 22, with which the heat sink 2 rests on an outer surface of the cover 12. A material-bonded connection 3, in particular a brazed connection or a welded connection, is formed between the circumferential rim 22 and the cover 12 (see Figure 3).

[0058] A further material-bonded connection 3 is provided between the protruding cooling elements 21 and an inner surface 12a on the cooling channel of the base body 11. This ensures secure fixation of the cooling element 2 on the one hand to the base body 11 at the circumferential edge 22 and on the other hand to the protruding turbulator structures 21 on the cover 12.

[0059] As can be seen from Figure 4, there is a material-bonded connection 3 between the stainless steel components cover 12 and base body 11, inlet nozzle 14 and base body 11. Also shown is a liquid-bonded connection 3 between the copper heat sink 2 and the stainless steel components base body 11 and cover 12.

[0060] A connection surface 24 is formed on the outer side of the base plate 20, which serves as a mounting surface for the power electronic elements 4. As shown schematically in Figure 3, the power electronic elements 4 are attached by means of a metallurgical bond 17, in particular a soft solder layer or sintered layer. In this embodiment, several power electronic elements 4 are mounted on a heat sink 2.

[0061] Figure 3 schematically shows the flow through the cooler assembly 1. Arrow 6 indicates the inflow of a cooling fluid into the cooler assembly. The cooling fluid is deflected by 90 degrees and flows through the cooling channel 16 (arrow 5) and is deflected again by 90 degrees at the outlet nozzle 15 before flowing out of the outlet nozzle 15 (arrow 7). During its flow through the cooling channel 16, the cooling fluid comes into contact with the protruding turbulator structures 21 and carries away heat. This ensures that the power electronic components 4 are reliably cooled.

[0062] As can be clearly seen in Figures 2 and 3, fluid-tight, metallurgical connections 3 are formed on all components. These can be produced in a single brazing process, enabling a particularly cost-effective and reliable connection of the components. Naturally, this ensures the fluid tightness of the cooling channel 16. However, it is also possible to produce the metallurgical connections by welding or a combination of brazing and welding.

[0063] Compared to the prior art, which uses, for example, cooler assemblies made entirely of copper, the cooler assembly 1 according to the invention offers a significant cost advantage, since a large part of the cooler assembly 1 can be manufactured from relatively inexpensive stainless steel. The heat dissipation performance of the cooler assembly 1 according to the invention is no worse than that of a cooler assembly made entirely of copper according to the prior art, since the heat sinks 2 are made entirely of copper. Thus, according to the invention, copper can be replaced by more cost-effective stainless steel without any loss of cooling performance. Since copper and certain grades of stainless steel have essentially the same coefficients of thermal expansion, no additional thermomechanical stresses are present.

[0064] Furthermore, the cooler arrangement 1 according to the invention can exhibit high mechanical strength due to the use of stainless steel as the main component of the cooler housing 10. This eliminates the need for additional mechanical reinforcements, particularly in the cooling channel 16, which would have adverse effects on the flow through the cooling channel 16. The inlet nozzle 14 and the outlet nozzle 15 are preferably turned parts made of stainless steel, which are significantly easier to machine compared to copper. The large number of available stainless steel alloys allows for flexible selection of the stainless steel to meet the system requirements of the cooler arrangement 1.

[0065] The copper heat sink 2 can be an extruded structure, for example a pin-fin heat sink, or a heat sink made from stamped and bent parts, which can also be assembled into a complete heat sink during the brazing process.

[0066] In the following embodiments, identical or functionally identical parts are designated by the same reference numerals as in the first embodiment.

[0067] Figures 5 to 7 schematically show a second embodiment of the cooler arrangement 1. In this embodiment, several dedicated heat sinks 2 are inserted into the cooler housing 10. In contrast to the first embodiment, a heat sink 2 can thus be used for each power electronic element 4. This allows the turbulator structures 21, in particular pin-fin, strip-fin, or wave-shaped rib structures, to be selectively optimized to the system boundary conditions of the cooler arrangement 1. Standardization of the metallurgical bond of the power electronic elements on the joining surface 24 is also possible. Adaptation of the cooler housing 10 is possible largely without affecting the base plate 20 or the metallurgical bond.

[0068] Figure 8 is a schematic sectional view of a cooler arrangement 1 according to a third embodiment of the invention. In contrast to the first embodiment, in this embodiment the copper heat sink 2 is formed in two parts. The heat sink 2 comprises a separate base plate 20 and a separate stamped and bent part as a turbulator structure 21. The stamped and bent part can, for example, have a profile with a wave-like shape in the flow direction, be a straight cooling fin, or be a strip-fin cooling fin. The turbulator structure 21 is connected to the base body 11 on one side and to the base plate 20 on the opposite side by means of a brazed connection 3. All copper components, and in particular the heat sink 2, are passivated by a layer 9 to prevent corrosion in the coolant system.Layer 9 can be applied to the base plate 20 chemically or electrochemically, or mechanically, for example by roller plating.

[0069] Figure 9 shows a cooler arrangement 1 according to a fourth embodiment of the invention. The fourth embodiment corresponds essentially to the third embodiment, wherein layer 9 additionally assumes the function of the brazing alloy. For example, a coating is used that forms a stable brazing compound between copper and copper as well as between copper and stainless steel. This allows for particularly easy placement of the individual parts before brazing, since the brazing alloy elements are no longer needed.

[0070] Figure 10 shows a cooler arrangement according to a fifth embodiment of the invention. The fifth embodiment corresponds essentially to the first embodiment, wherein the copper heat sink 2 is completely provided with a layer 9, in particular a coating. All copper components, and especially the heat sink 2, are passivated by a coating to prevent corrosion in the coolant system. The heat sink 2 is again connected to the inside of the base body 11 in the cooling channel 16 by a hard solder joint 3, both to the base body 11 and at the cooling elements 21. In this embodiment, the heat sink is manufactured as a single piece, either as an extruded or forged component, for example as a pin-fin.

[0071] Figure 11 shows a sixth embodiment of the invention, wherein, in contrast to the embodiment of Figure 10, layer 9 additionally assumes the function of the hard solder. For example, a coating is used that forms a stable solder joint between copper and copper as well as between copper and stainless steel.

[0072] In contrast to the third and fourth embodiments, in the fifth and sixth embodiments the heat sink 2 is manufactured as a single piece. This can be an extruded or forged pin-fin heat sink.

[0073] As shown in the exemplary embodiments, the invention provides a cost-effective cooler assembly 1 in which a heat sink 2 is made of copper and the remaining part of the cooler assembly 1, in particular the cooler housing 10 including the inlet nozzle 14 and the outlet nozzle 15, can be made of a more cost-effective stainless steel. This allows the same cooling performance to be achieved at reduced costs as with a cooler assembly made entirely of copper. To protect the components, especially the copper components of the cooler assembly 1 of the invention, coatings 9 can be applied to all surfaces that come into contact with the cooling fluid. Alternatively, a coating can also be applied to the surfaces of the stainless steel cooler housing 10, particularly to the inner surfaces.

Claims

Claims 1. Cooling arrangement for power electronics, comprising: - a cooler housing (10) in which at least one continuous recess (13) is arranged, wherein the cooler housing defines a cooling channel (16), - wherein the cooler housing (10) is made of stainless steel, and - a copper heat sink (2) which is arranged in the recess (13) of the cooler housing (10), - wherein a fluid-tight connection is formed between the heat sink (2) and the cooler housing (10).

2. Cooler arrangement according to claim 1, wherein the cooler housing (10) has a base body (11) and a cover (12) which are connected to each other by means of a fluid-tight connection or wherein the cooler housing is formed in one piece.

3. Cooler arrangement according to one of the preceding claims, wherein the cooler housing (10) has an inlet port (14) and an outlet port (15) made of stainless steel, wherein in particular the inlet port (14) and the outlet port (15) are connected to the cooler housing by means of a fluid-tight connection.

4. Cooler arrangement according to one of the preceding claims, wherein the fluid-tight connection (3) is a brazed connection or a welded connection or a combination thereof.

5. Cooler arrangement according to one of the preceding claims, wherein the copper-made heat sink (2) is two-part with a base plate (20) as a stamped part and a turbulator structure (21) as a stamped-bent component, in particular a profile with a corrugated shape in the direction of a coolant flow, a straight rib profile or a strip-fin rib profile, or wherein the copper heat sink (2) is an extrusion component, in particular a pin-fin component.

6. Cooler arrangement according to one of claims 2 to 5, wherein the base body (11) and / or the cover (12) is a deep-drawn component and / or a stamped component.

7. Cooler arrangement according to one of the preceding claims, wherein the copper-made heat sink (2) has a passivating layer (9) in all areas which are directed towards the cooling channel (16) and which can come into contact with a cooling fluid.

8. Cooler arrangement according to claim 7, wherein the heat sink (2) is completely covered with a passivating layer (9).

9. Cooler arrangement according to claim 7 or 8, wherein the passivating layer (9) is used as a brazing alloy to produce a fluid-tight connection between the cooling element (2) and the cooler housing (10).

10. Cooler arrangement according to one of the preceding claims, wherein all components of the cooler arrangement to be joined together are formed by means of a material-bonded connection (3) in particular a brazing connection.

11. Method for manufacturing a cooling assembly (1) for power electronics, comprising the steps: Providing a stainless steel cooler housing (10) defining a cooling channel (16) in which at least one recess (13) is formed, Arrangement of a copper heat sink (2) in the recess such that the heat sink (2) seals the recess (13) in a fluid-tight manner, in particular with an edge (20) of the heat sink (2) on an outer surface of the cooler housing (10), wherein turbulator structures (21) of the heat sink (2) project into the cooling channel (16) and Welding or brazing, in particular brazing, of the heat sink (2) to the cooler housing (10) to seal the cooling channel (16) in a fluid-tight manner.

12. Method according to claim 11, wherein the cooler housing (10) is formed in two parts with a base body (11) and a cover (12), and the base body (11) is connected to the cover (12) by means of a material-bonded connection (3), in particular as a welded connection or as a brazed connection, wherein the brazing process is carried out simultaneously with the brazing process for fixing the heat sink (2) to the cooler housing (10).

13. Method according to claim 11 or 12, wherein all surfaces of the cooling element (2) which are arranged in the cooling channel (16) in the assembled state and come into contact with the cooling fluid flowing through the cooling channel (16) have a passivating layer (9).

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