Heat sinks for cooling electronic components

Abstract

Heat sinks for cooling electronic components (22) with - a base body (12) with an outer surface (18) for thermal connection to at least one electronic component (22) to be cooled; - a cooling channel (14) for a cooling fluid, which is arranged in the base body (12) and is bounded by an inner surface (20) of the base body (12); and - at least one cooling fin (16) which is arranged in the cooling channel (14) and extends from a first section (24) of the inner surface (20) to a second section (26) of the inner surface (20), wherein the at least one cooling fin (16) is formed in one piece with the base body (12) over the first section (24) of the inner surface (20) and over the second section (26) of the inner surface (20) and has an at least partially rounded cross-section (28) transverse to the flow direction (30) of the cooling fluid.

Description

State of the art

[0001] The invention relates to a heat sink for cooling electronic components and a method for manufacturing a heat sink for cooling electronic components.

[0002] The power electronics of electric vehicles are now water-cooled. A copper plate with pin fins (pin-shaped cooling fins) on its underside is screwed into an aluminum housing with a gasket. Cooling water flows through this housing. The pin fins must not touch the housing during tightening, otherwise the gasket will no longer seal properly. The power electronics circuitry is connected to the top of the copper plate. The heat generated by the semiconductors is dissipated through the copper plate and via the pin fins into the cooling water.

[0003] The geometry and arrangement of the pinfins on the underside of the copper plate are of particular importance, as they are intended to increase the surface area to improve heat transfer, but on the other hand must not lead to a large pressure loss in the water.

[0004] The present invention aims to improve the heat transfer from the heat sources to the cooling water in the smallest possible installation space, without causing a significant pressure loss.

[0005] DE 101 14 998 A1 discloses the use of phase-change materials in coolers for electrical and electronic components. DE 101 34 187 A1 discloses a cooling device for cooling semiconductor components and semiconductor modules. DE 10 2011 101 302 A1 discloses a housing with a cooling line which is built up layer by layer using an additive manufacturing process. Disclosure of the invention

[0006] Against this background, the approach presented here introduces a heat sink for cooling electronic components and a method for manufacturing a heat sink according to the main claims.

[0007] The approach presented here creates a heat sink for cooling electronic components with - a base body with an outer surface for thermal connection to at least one electronic component to be cooled; - a cooling channel for a cooling fluid, which is arranged in the base body and is bordered by an inner surface of the base body; and - at least one cooling fin which is arranged in the cooling channel and extends from a first section of the inner surface to a second section of the inner surface, wherein the at least one cooling fin is formed integrally with the base body over the first section of the inner surface and over the second section of the inner surface and has a cross-section that is at least partially rounded transverse to a flow direction of the cooling fluid.

[0008] The approach presented here also provides a method for manufacturing a heat sink for cooling electronic components, comprising the following steps: - Creating a basic body with an outer surface for thermal connection to at least one electronic component to be cooled; - Creating a cooling channel for a cooling fluid in the base body such that the cooling channel is enclosed by an inner surface of the base body; and - Generating at least one cooling fin in the cooling channel such that the at least one cooling fin extends from a first section of the inner surface to a second section of the inner surface and is formed integrally with the base body over the first section of the inner surface and over the second section of the inner surface, and that the at least one cooling fin has at least partially a rounded cross-section transverse to a flow direction of the cooling fluid, wherein the generation steps are carried out by means of an additive manufacturing process, in particular by means of binder jetting or SLM.

[0009] Within the scope of the present invention, an electronic component can be understood to be any active and passive component or high-performance component. The electronic component can be, for example, a semiconductor device, a sensor element, an inductor, a capacitor, a battery cell, a battery module, or a circuit arrangement.

[0010] The base body is preferably formed in one piece. The base body may be made of copper (Cu) or consist entirely of copper. The base body may have a closed outer surface to increase the thermal contact area for the electronic components to be cooled without significantly increasing the overall size of the heat sink.

[0011] The outer surface of the base body can have at least one flat section to facilitate thermal connection to flat contact surfaces of electronic components. Alternatively or additionally, the outer surface of the base body can have at least one curved section to improve thermal connection to curved contact surfaces of electronic components, e.g., in an electric machine. The outer surface of the base body can be cylindrical, particularly prismatic. The base body can, for example, be prismatic with three or four flat outer surfaces, or in any other shape with flat outer surfaces of varying sizes.

[0012] The inner surface of the base body can have at least one flat section. Alternatively or additionally, the inner surface of the base body can have at least one curved section. The inner and outer surfaces of the base body can be at least partially parallel.

[0013] The cooling fluid can be, for example, water or a water-glycol mixture.

[0014] Within the scope of the present invention, any description relating to a single cooling fin shall be understood to apply to a group of cooling fins or to all cooling fins of the heat sink, without explicitly referring to the plural "cooling fins." The cooling fin has a rounded cross-section perpendicular to the flow direction of the cooling fluid. Accordingly, the cooling fin is arranged in the cooling channel, perpendicular to the flow direction of the cooling fluid, allowing the cooling fluid to flow around it. The cooling fin has a cross-section or a section with a cross-sectional area that is at least partially rounded or curved. The rounded section is preferably located at the stagnation point that occurs when the cooling fluid flows around the cooling fin. The cooling fin can be made of solid material, i.e., it can be free of cavities. However, the cooling fin can also have cavities.The cooling fin may contain copper or be made of copper.

[0015] In the context of the present invention, an additive manufacturing process is understood to be binder jetting or SLM (selective laser melting). The steps of producing the base body, the cooling channel, and the at least one cooling fin are preferably carried out in a single step, e.g., a single step of 3D printing.

[0016] The heat sink and method according to the invention enable the simple realization of a type of 3D heat sink with a multitude of design possibilities, which features a compact design with optimized heat transfer to the cooling fluid. This is achieved in particular by the fact that the heat sink, i.e., the base body with the cooling fins, is formed in one piece and the design of the cooling fins and the base body can be adapted almost arbitrarily to the desired thermal requirements in order to optimize heat transfer and flow pressure loss.

[0017] It is advantageous if at least one further cooling fin is provided, which is arranged in the cooling channel and extends from the first section of the inner surface to the second section of the inner surface, wherein the at least one cooling fin has an at least partially rounded cross-section and is formed integrally with the base body over the first section of the inner surface and over the second section of the inner surface. It is particularly advantageous if the cooling fins are arranged offset in the flow direction of the cooling fluid.It is further advantageous to provide a plurality of cooling fins arranged in the cooling channel, each extending from the first section of the inner surface to the second section. These cooling fins have an at least partially rounded cross-section and are integrally formed with the base body over both the first and second sections of the inner surface. It is particularly advantageous if the cooling fins are arranged offset both in and across the flow direction of the cooling fluid. Depending on the requirements and the arrangement of the electronic components, the cooling fins can be arranged regularly or irregularly. This allows for various cooling fin arrangements, enabling better adaptation to the thermal gradient in the flow direction of the cooling fluid.

[0018] It is also advantageous if at least one cooling fin extends to at least one further section of the inner surface of the base body and is integrally formed with the base body over this further section of the inner surface. This design allows the surface area of ​​the cooling fin to be further increased, thereby improving heat transfer.

[0019] Furthermore, it is advantageous if the cooling channel has at least two sub-channels, which are divided by at least one cooling fin and run at an angle and / or intertwined relative to each other. In other words, the sub-channels do not run parallel but are angled and / or intertwined or twisted relative to each other. This measure allows, for example, in the case of multiple heat sources or electronic components located in the direction of flow of the cooling fluid, a separate sub-channel with unheated cooling fluid to be provided for each heat source or electronic component. This improves heat transfer and cooling efficiency, particularly at hotspots.

[0020] Furthermore, it is advantageous if at least one cooling fin has at least a partially circular, elliptical, teardrop-shaped, or streamlined cross-section. In other words, the cooling fin has a flow-optimized cross-section, which allows for better adaptation to the temperature gradient in the flow direction of the cooling fluid and results in lower pressure loss.

[0021] Furthermore, it is advantageous if the base body has at least two sections with different thermal conductivity from the outer surface to the inner surface of the base body, or with different heat capacities between the outer and inner surfaces of the base body. Advantageously, the base body can also have at least two sections with different wall thicknesses. Consequently, the wall thickness of the heat sink can be locally thinner or thicker. This design allows the heat sink to be adapted to specific sections depending on whether high thermal conductivity or high heat capacity is required.

[0022] It is also advantageous if the base body has a first material on its inner surface and a second material on its outer surface. It is particularly advantageous if the first material is Cu, i.e., copper, and the second material is a graded material, especially a Cu-W alloy, i.e., a tungsten-copper alloy, and / or Cu with embedded Al₂O₃ particles, i.e., aluminum oxide particles. Here, the term "in the inner surface" refers specifically to the area extending from the inner surface towards the outer surface of the base body. Furthermore, the term "in the outer surface" refers specifically to the area extending from the outer surface towards the inner surface of the base body. Thus, for example, for good thermal conductivity, the material can be changed from Cu inside the heat sink to a Cu-W alloy on the outside of the heat sink.Since Cu-W has a lower coefficient of thermal expansion than Cu, lower thermal stresses occur on the outer surface of the heat sink at the interface with, for example, a ceramic insulator, leading to increased reliability. Alternatively or additionally, a grade can be applied from Cu to Cu with embedded Al₂O₃ particles to locally increase strength, for example, to enable thread cutting.

[0023] It is further advantageous if the base body has at least one cavity in which a phase change material is arranged, and in particular, a lattice structure is also arranged in the cavity, which is integrally formed with the base body. This configuration can be achieved, for example, by providing at least one cavity with a lattice structure in the base body during the manufacturing step, and by placing a phase change material into the cavity during the assembly step. The cavities are then sealed. The arrangement of a phase change material in the base body creates a latent heat storage medium, which increases the heat capacity. By advantageously providing the cavities with metallic lattice structures, the heat transfer to the phase change material can be improved.

[0024] It is also advantageous if at least one tab and / or eyelet and / or sealing joint and / or a cooling fluid connection is provided, which is formed integrally with the base body. The eyelet and / or tab allows the heat sink to be attached to, for example, a housing or similar structure. The eyelet and / or tab can be made of solid ODS copper (oxide dispersion-hardened copper alloy) or consist entirely of solid ODS copper. The sealing joint provides external protection against splashing water or similar elements. The cooling fluid connection allows the heat sink to be connected to a cooling fluid line, eliminating the need for screwing it into a water-carrying housing. This design allows for the simple integration of additional functional sections into the heat sink, as these can be incorporated or 3D printed during the manufacturing process of the base body or the heat sink itself.

[0025] Furthermore, it is advantageous if at least one thread is created during the manufacturing process of the base body or the heat sink. This means that a thread is simultaneously provided or printed during the manufacturing step of the base body. Consequently, the closed heat sink can be screwed directly onto a housing, with the screw connection requiring no thermal connection as it serves only for fastening. Drawings

[0026] The invention is explained in more detail below with reference to the accompanying drawings. These show: Fig. 1 a schematic representation of a first embodiment of a rectangular heat sink according to the invention; Fig. 2 a schematic representation of a second embodiment of a triangular heat sink according to the invention; Fig. 3 a schematic representation of a cross-sectional view of a cooling fin arrangement; Fig. 4 a schematic representation of an arrangement of intertwined partial fluid channels; Fig. 5 a schematic representation of a cross-sectional view of a heat sink with cavities containing phase change material; Fig. 6 a flowchart of a process for manufacturing a cooling element according to the invention.

[0027] In Fig. 1 is a heat sink according to the invention for cooling electronic components in its entirety, provided with the reference numeral 10.

[0028] The heat sink 10 has a base body 12, a cooling channel 14 and a plurality of cooling fins 16.

[0029] The base body 12 has an outer surface 18 and an inner surface 20. The outer surface 18 of the base body 12 serves for the thermal connection of electronic components 22. In the illustrated embodiment, the base body 12 has a closed prismatic shape with a rectangular cross-section at the outer surface 18. The outer surface 18 thus has four flat sections. The inner surface 20 of the base body 12 defines or delimits the cooling channel 14.

[0030] The cooling channel 14 is therefore arranged in or runs within the base body 12. The cooling channel 14 serves to guide or direct a cooling fluid. Cooling fluid connection nozzles, which direct the cooling fluid into the cooling channel 14, are not shown.

[0031] The cooling fins 16 are arranged in the cooling channel 14. They are positioned in such a way that the cooling fluid flows around them, thereby increasing the surface area for heat conduction from the electronic components 22 into the cooling fluid. The cooling fins 16 extend from a first section 24 of the inner surface 20 to a second section 26 of the inner surface 20. Thus, the cooling fins 16 contact the base body 12 at two points: at the first section 24 and at the second section 26. The cooling fins 16 are integrally formed with the base body 12 at both the first section 24 and the second section 26. Consequently, the base body 12, the cooling channel 14, and the cooling fins 16 are formed as a single unit and are interconnected. Accordingly, the entire heat sink 10 is formed in one piece.The cooling fins 16 have a rounded cross-section 28 (shown with dotted lines) perpendicular to the flow direction 30 of the cooling fluid. The cross-sectional shapes will be described in the section on... Fig. 3 discussed in more detail.

[0032] In Fig. Figure 2 shows a further embodiment of a heat sink 10' according to the invention. The heat sink 10' also has a base body 12 with a prismatic shape. Contrary to the one shown in Fig. In the embodiment shown in Figure 1, however, the base body 12 of the heat sink 10' has a triangular cross-section on its outer surface 18. The outer surface 18 thus has three flat sections for the thermal connection of the electronic components 22.

[0033] Another difference from the heat sink 10 is that some of the numerous cooling fins 16 of the heat sink 10' are branched. Accordingly, the cooling fins 16 extend partially to further sections 32 of the inner surface 20 of the base body 12, forming a net-like structure.

[0034] The cooling fins 16 are also partially elongated and extend in the flow direction 30 of the cooling fluid. This forms partial cooling channels 34, which are separated by the cooling fins 16. The course of the partial cooling channels will be described in more detail in the following section. Fig. 4 discussed in more detail.

[0035] Fig. Figure 3 shows a cross-sectional view of an arrangement of cooling fins 16. It can be seen that the cooling fins 16 have a rounded cross-section 28, around which the cooling fluid flows. The cooling fins 16 have a circle or an ellipse as their cross-section 28. However, any flow-optimized shape known to those skilled in the art, such as a teardrop shape or a streamlined shape, is conceivable without departing from the scope of the invention. As further shown in Fig. As can be seen in Figure 3, the cooling fins 16 are arranged and aligned differently relative to each other, since any design or arrangement can be realized using the method according to the invention.

[0036] Fig. Figure 4 shows an arrangement of intertwined partial fluid channels 34. It can be seen that the fluid channel 14 is partially divided into three partial fluid channels 34 by the cooling channels 16. The partial fluid channels 34 are intertwined with each other. The partial fluid channels 34 are designed such that a separate partial fluid channel 34 is provided for each of the electronic components 22 arranged one behind the other in the flow direction. Thus, a separate partial flow with unheated cooling fluid is advantageously provided for each heat source or electronic component 22. This further improves heat transfer and cooling efficiency.

[0037] Fig. Figure 5 is a cross-sectional view of a base body 12 with cavities 36. The cavities 36 have a lattice structure 38. The lattice structure 38 is formed integrally with the base body 12. A phase-change material 40 is arranged in the cavities 36 to increase the heat capacity of the base body 12 and / or the heat sink 10, 10'.

[0038] Fig.Figure 6 shows a flowchart of a method 100 for manufacturing a heat sink 10, 10' according to the invention for cooling electronic components 22. The method 100 comprises a step 102 of producing a base body 12 with an outer surface 18 for thermal connection to at least one electronic component 22 to be cooled. Furthermore, the method 100 comprises a step 104 of producing a cooling channel 14 for a cooling fluid in the base body 12 such that the cooling channel 14 is bounded by an inner surface 20 of the base body 12.Finally, the method 100 comprises a step 106 of producing at least one cooling fin 16 in the cooling channel 14 such that the at least one cooling fin 16 extends from a first section 24 of the inner surface 20 to a second section 26 of the inner surface 20 and is formed integrally with the base body 12 over the first section 24 of the inner surface 20 and over the second section 26 of the inner surface 20, and that the at least one cooling fin 16 has at least a partially rounded cross-section 30 transverse to a flow direction 28 of the cooling fluid. All steps 102, 104, 106 of producing the base body 12, the cooling channel 14, and the at least one cooling fin 16 are carried out by means of an additive manufacturing process, in particular by means of binder jetting or SLM.All steps 102, 104, 106 of producing the base body 12, the cooling channel 14 and the at least one cooling fin 16 are preferably carried out in only one single manufacturing step.

[0039] Furthermore, it is possible in the step of generating the base body 102 to create a tab and / or eyelet and / or sealing joint and / or a cooling fluid connection nozzle and / or a thread on the base body 12.

[0040] Optionally, in step 102 of generating the base body 12, at least one cavity 36 with a lattice structure 38 can be provided in the base body 12, and in an additional step 108 of arranging, a phase change material 40 can be arranged in the cavity 36, followed by closing the cavity 36.

[0041] If an embodiment includes an “and / or” connection between a first feature and a second feature, this is to be read as meaning that the embodiment according to one embodiment has both the first feature and the second feature, and according to another embodiment either only the first feature or only the second feature.

Claims

[1] Heat sink for cooling electronic components (22) with - a base body (12) with an outer surface (18) for thermal connection to at least one electronic component (22) to be cooled; - a cooling channel (14) for a cooling fluid, which is arranged in the base body (12) and is bounded by an inner surface (20) of the base body (12); and - at least one cooling fin (16) which is arranged in the cooling channel (14) and extends from a first section (24) of the inner surface (20) to a second section (26) of the inner surface (20), wherein the at least one cooling fin (16) is formed in one piece with the base body (12) over the first section (24) of the inner surface (20) and over the second section (26) of the inner surface (20) and has an at least partially rounded cross-section (28) transverse to the flow direction (30) of the cooling fluid. [2] Heat sink (10, 10') according to claim 1, characterized byat least one further cooling fin (16) which is arranged in the cooling channel (14) and extends from the first section (24) of the inner surface (20) to the second section (26) of the inner surface (20), wherein the at least one further cooling fin (16) is formed in one piece with the base body (12) over the first section (24) of the inner surface (20) and over the second section (26) of the inner surface (20) and has an at least partially rounded cross-section (28) transverse to the flow direction (30) of the cooling fluid. [3] Heat sink (10, 10') according to claim 2, characterized by , that the cooling fins (16) are arranged offset in the direction of flow (30) of the cooling fluid. [4] Heat sink (10, 10') according to any of the preceding claims, characterized bya plurality of cooling fins (16) which are arranged in the cooling channel (14) and each extend from the first section (24) of the inner surface (20) to the second section (26) of the inner surface (20), wherein the cooling fins (16) are formed in one piece with the base body (12) over the first section (24) of the inner surface (20) and over the second section (26) of the inner surface (20) and each have an at least partially rounded cross-section (28) transverse to the flow direction (30) of the cooling fluid. [5] Heat sink (10, 10') according to claim 4, characterized by , that the cooling fins (16) are arranged offset in and across the flow direction (30) of the cooling fluid. [6] Heat sink (10, 10') according to any of the preceding claims, characterized by, that at least one cooling fin (16) extends to at least one further section (32) of the inner surface (20) of the base body (12) and is formed integrally with the base body (12) over the further section (32) of the inner surface (20). [7] Heat sink (10, 10') according to any of the preceding claims, characterized by , that the cooling channel (14) has at least two partial cooling channels (34) which are divided by at least one cooling fin (16) and run skew and / or intertwined with each other. [8] Heat sink (10, 10') according to any of the preceding claims, characterized by , that at least one cooling fin (16) has at least partially a circular, elliptical, teardrop or streamlined cross-section (28). [9] Heat sink (10, 10') according to any one of the preceding claims, characterized by , that the basic body (12) is formed in one piece. [10] Heat sink (10, 10') according to any one of the preceding claims, characterized by , that the basic body (12) has a closed outer surface (18). [11] Heat sink (10, 10') according to any of the preceding claims, characterized by , that the base body (12) has at least two sections of different heat conduction from the outer surface (18) to the inner surface (20) of the base body (12) or of different heat capacity between the outer surface (18) and the inner surface (20) of the base body (12). [12] Heat sink (10, 10') according to any one of the preceding claims, characterized by , that the basic body (12) has at least two sections of different wall thickness. [13] Heat sink (10, 10') according to any of the preceding claims, characterized by , that the basic body (12) has a first material in the area of ​​the inner surface (20) and a second material in the area of ​​the outer surface (18). [14] Heat sink (10, 10') according to claim 13, characterized by , that the first material is copper and the second material is a graded material, in particular a tungsten-copper alloy, and / or copper with embedded aluminum oxide particles. [15] Heat sink (10, 10') according to any of the preceding claims, characterized by , that the base body (12) has at least one cavity (36) in which a phase change material (40) is arranged, wherein in particular a lattice structure (38) is further arranged in the cavity (36), which is formed integrally with the base body (12). [16] Heat sink (10, 10') according to any of the preceding claims, characterized by at least one tab and / or eyelet and / or sealing joint and / or a cooling fluid connection nozzle, which is formed in one piece with the base body (12). [17] Cooling sink (10, 10') according to any of the preceding claims, manufactured by an additive manufacturing process. [18] Method for manufacturing a heat sink for cooling electronic components (22) comprising the following steps: - Generating (102) a base body (12) with an outer surface (18) for thermal connection to at least one electronic component (22) to be cooled; - Creating (104) a cooling channel (14) for a cooling fluid in the base body (12) such that the cooling channel (14) is bounded by an inner surface (20) of the base body (12); and - Generating (106) at least one cooling fin (16) in the cooling channel (14) such that the at least one cooling fin (16) extends from a first section (24) of the inner surface (20) to a second section (26) of the inner surface (20) and is formed integrally with the base body (12) over the first section (24) of the inner surface (20) and over the second section (26) of the inner surface (20), and that the at least one cooling fin (16) has at least partially a rounded cross-section (28) transverse to a flow direction (30) of the cooling fluid, wherein the generating steps (102, 104, 106) are carried out by means of an additive manufacturing process, in particular by means of binder jetting or SLM. [19] Method for manufacturing a cooling element according to claim 19, characterized by, that in the step of generating (102) the base body (12) at least one cavity (36) with a lattice structure (38) is provided in the base body (12), and in a step of arranging (108) a phase change material (40) is arranged in the cavity (36). [20] Method for manufacturing a cooling element according to claim 19 or 20, characterized by , that in the step of generating (102) the base body (12) at least one thread is generated.

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