Heat sink with heat pipe for electronic components and corresponding assembly

Abstract

The invention relates to a heat sink (1) for an electronic component (100), characterized in that the heat sink (1) comprises an air heat exchanger (2) provided with a number of fins (3, 4) delimiting an air duct (5) passing through the air heat exchanger (2), the fins (3, 4) being at least partially in the form of heat pipes (6). Furthermore, a corresponding assembly is described.

Description

[Technical field]

[0001] The invention is based on a heat sink for electronic components, which has an air heat exchanger with a number of fins that delimit an air duct through the air heat exchanger. Such a heat sink is described in German Patent Publication 10 2004 023 037 B4. [Background technology]

[0002] With the increase in power density of electronic components such as IT components and inverters and the increasing computing power of microchips (CPU, GPU), the heat generation also increases. The air heat exchangers used so far are often in the form of aluminum blocks and therefore have limited dissipation capacity. Further developments in the field of microchip technology allow chip powers of up to 400 watts per chip, for example. Due to the increase in power density, known air heat exchangers are no longer suitable to dissipate the resulting power losses to a sufficient extent. New cooling techniques such as "direct chip cooling" allow components to be cooled effectively, but these techniques are significantly more complex and relatively less resistant to failures than, for example, air heat exchangers integrated into CPUs or GPUs. Heat pipes known from the prior art based on copper tubes and aluminum fins also have limited cooling capacity. Summary of the Invention [Problem to be solved by the invention]

[0003] It is therefore an object of the present invention to further develop a heat sink with an air heat exchanger such that it has the highest possible cooling power density. [Means for solving the problem]

[0004] This object is achieved by a heat sink with the features of claim 1. Independent claim 12 relates to a corresponding assembly. Advantageous embodiments are the subject matter of the respective dependent claims.

[0005] The heat sink is therefore provided with fins of the air heat exchanger in the form of at least partly heat pipes, the use of which allows the power losses to be efficiently distributed over the entire volume of the air heat exchanger, resulting in improved heat exchange with the air flowing through the air heat exchanger and thus an increased efficiency of the heat sink.

[0006] The fins in the form of heat pipes can each have at least one vertical hollow conductor or microchannel through which the working medium of the heat pipe is guided. The fins can therefore be in the form of hollow fins for medium guidance. The hollow fins can be formed between the evaporation zone in the lower region of the air heat exchanger and the cavity in the upper region of the air heat exchanger and open into the latter. Preferably, the heat pipes or fins can run parallel to each other. The fins in the form of hollow fins can therefore fluidly connect the medium volume of the evaporation zone to the cavity and all the heat pipes can be fluidly connected to each other via the evaporation zone and the cavity.

[0007] The air heat exchanger may be a microchannel heat exchanger, preferably without forward and reverse flows, with a volume of the working medium enclosed. The air heat exchanger may be provided, for example, in the case of a commercial microchannel heat exchanger, by filling the microchannel heat exchanger with a working medium, for example a two-phase refrigerant, and then closing any forward and reverse flows that may be present, so that the working medium is enclosed within the closed microchannel heat exchanger.

[0008] A microchannel heat exchanger may comprise several microchannels, each forming one of the heat pipes. The microchannels may be connected to each other by an evaporation zone and possibly an upper cavity. This improves the distribution of power losses across all the microchannels, and therefore the heat dissipation capacity. This also helps to avoid hot spots in the electronic components. Moreover, the loss area can be significantly increased beyond the contact area between the electronic component and the heat sink.

[0009] Preferably, each microchannel of the plurality of microchannels of the microchannel heat exchanger forms in each case one of the heat pipes.

[0010] The microchannel heat exchanger may have an evaporation zone into which the first ends of the microchannels open and through which the microchannels are fluidly connected to one another. The evaporation zone may be a reservoir for the working medium of the heat pipe formed by the microchannels.

[0011] The evaporation zone can be in direct or indirect thermal contact with a mounting surface of a heat sink for mounting the heat sink to the electronic component to be cooled. Preferably, the mounting surface of the heat sink and other components of the heat sink, in particular the heat pipes of the heat sink, e.g. the microchannel heat exchanger providing the heat pipes, are integrally formed and preferably made of the same material. Such heat sinks can be manufactured using additive manufacturing methods, e.g. build-up welding. The integral nature optimizes heat transfer between the mounting surface and the heat pipes or between the mounting surface and the evaporation zone of the heat pipes. A suitable material is aluminum or an aluminum-containing alloy.

[0012] The microchannel heat exchanger may have a cavity into which the microchannels may open a second end arranged opposite the first end. The cavity may be a component of the condensation zone of the heat pipe. However, in function, the heat sink does not require a separate condensation zone, as known in the heat pipe arrangements known in the prior art, since condensation occurs along the fins in the form of a heat pipe by the passage of air through the air heat exchanger. The cavity may therefore have the function of connecting the second ends of several heat pipes to each other, in particular to perform a fluid exchange between the heat pipes and thus optimize the efficiency of the heat sink by better distributing the cooling load over the volume of the heat sink.

[0013] In a preferred embodiment, the microchannel heat exchanger has, in addition to the fins in the form of heat pipes, further fins which extend substantially parallel to each other, are spaced apart from each other and extend substantially perpendicular to the fins in the form of heat pipes. In the installed situation, the fins in the form of heat pipes are oriented vertically, or substantially vertically, or at least partially vertically, in order to ensure optimal functioning of the heat pipes. The additional fins additionally present in the preferred embodiment may therefore be oriented substantially horizontally in the installed situation. The additional fins can have substantially two functions. Firstly, the fins serve for the heat transfer between the heat pipes, so that the required cooling load is better distributed over the entire volume of the heat sink or the local power losses of the electronic components to be cooled are dissipated in an optimal manner, thereby increasing the efficiency of the heat sink. Secondly, the additional fins form an additional surface for the heat transfer between the heat sink and the air flowing through it, in particular between the heat pipes and the air flowing through it.

[0014] Thus, the further fins may be in the form of solid fins made of a thermally conductive material, with adjacent fins in the form of heat pipes being thermally coupled to each other via a number of further fins.

[0015] The fins in the form of heat pipes can run parallel to one another and are spaced apart from one another by less than 10 mm, preferably less than 8 mm, particularly preferably less than 6 mm.

[0016] The fins in the form of heat pipes may each have a number of vertical and parallel microchannels arranged one behind the other in the longitudinal direction of the fins in the form of heat pipes. When vertically oriented fins for forming heat pipes are mentioned here, the situation of the installation of a heat sink on an electronic component is described here, but in order to maximize the efficiency of the heat pipes as much as possible, it is preferable that the heat sink is oriented so that the heat pipes are vertically oriented. For this purpose, it may be necessary, for example, for the heat pipes to extend perpendicular to the mounting surface on which the heat sink is mounted on the electronic component to be cooled. For this purpose, it may have, for example, a substantially horizontal fixing surface, through which the heat sink may be mounted, as is all customary in the case of CPUs, and the electronic component dissipates its power losses to the surroundings.

[0017] Each heat pipe fin may have a plurality of vertical, parallel microchannels arranged one behind the other along the length of the heat pipe fin.

[0018] According to another aspect, an assembly is described that includes at least one heat sink of the above type and an electronic component, the heat sink being placed in thermal contact with the electronic component. In this case, the heat pipe is in the form of or has a vertical hollow conductor or microchannel. The vertical hollow conductor or microchannel may extend at least partially vertically to ensure optimal functioning of the heat pipe. The heat pipe may be placed at an angle to the vertical, in which case the function of the heat pipe decreases as the height difference between the evaporation zone and the upper end, e.g. the condensation zone, decreases. Similarly, the heat pipe should extend substantially perpendicular to the electronic component to be cooled in order to optimize the dissipation of heat from the electronic component.

[0019] The heat sink may be in thermal contact with the electronic component via a mounting surface of the heat sink, which may be the thermally coupled side of the evaporation zone of the heat pipe.

[0020] The heat sink may have cavities on its exterior opposite the evaporation zone into which the vertical hollow conductors or microchannels of the heat pipes open, so that fluid transition between the heat pipes may be provided via the cavities.

[0021] Furthermore, the assembly may comprise an airflow generator, for example a fan, which transports air through the air conducting channels and around the fins in the form of heat pipes. The fan may for example be a radial fan. [Brief description of the drawings]

[0022] Further details of the invention are explained with reference to the following figures. [Figure 1] FIG. 1 is a partial cross-sectional perspective view of an exemplary embodiment of a heat sink. [Diagram 2] FIG. 2 is a horizontal cross-sectional view showing the embodiment of FIG. [Diagram 3] 1 illustrates an embodiment of an assembly according to the present invention including a heat sink and an IT component. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Figures 1 and 2 show a first embodiment of a heat sink 1 according to the invention. The heat sink 1 can be provided in one piece and can be constructed from a thermally conductive material, preferably aluminium or an aluminium alloy, for example with additive manufacturing methods such as build-up welding. Additive manufacturing methods known from the prior art are particularly suitable for forming microstructures such as microchannel heat exchangers, which are substantial components of the embodiment of the heat sink 1 according to Figure 1.

[0024] The heat sink 1 thus comprises an air heat exchanger 2 with a number of fins 3, 4 which delimit an air duct 5 through the air heat exchanger 2, as is known in principle for heat sinks for IT components known in the prior art. The heat sink according to the invention is characterized in that the fins 3, 4 are at least partially in the form of heat pipes 6. In this case, the fins 3, which are vertical in the figure, are in the form of hollow conductors or microchannels 7, through which the working medium 8 of the heat pipes 6 is guided. In the base region, the heat sink 1 comprises a mounting surface 9, via which the heat sink 1 can be mounted to the IT component to be cooled (not shown, see IT component 100 in FIG. 3). The power losses dissipated by the IT component to be cooled can be directly coupled to the evaporation zone 10 of the heat pipes 6 via the mounting surface 9. All heat pipes 6 are fluidly connected to one another via the evaporation zone, so that even if a thermal coupling to the mounting surface occurs locally, e.g. depending on the shape and design of the IT component to be cooled, an optimal distribution of the power losses over the mounting surface 9 or evaporation zone 10 is provided, so that the heat pipes 6 can act evenly or approximately equally and consequently contribute to the dissipation of the power losses.

[0025] The fins 3 in the form of hollow conductors or microchannels 7 are substantially vertically oriented and spaced parallel to one another, the spacing of the vertical fins 3 being less than 10 mm. Due to the high packing density of the vertical fins 3 and the heat pipes, a high cooling capacity is obtained even if the structural volume of the heat sink 1 is relatively small. Adjacent vertical fins 3 are connected to one another via further horizontally oriented solid fins 4, and due to the good thermal conductivity of both the vertical fins 3 and the further horizontal fins 4, in the case of an air flow passing through the heat sink 1, an optimal heat exchange can take place between the heat pipes and the air flow. The horizontal fins 4 thus not only increase the effective surface area between the air and the heat sink 1 enabling the heat transfer, but also help in the heat transfer and load equalization between the heat pipes.

[0026] In the upper horizontal outer part of the heat sink 1, a cavity 11 is formed, arranged opposite the mounting surface 9 of the heat sink 1, through which the ends of the heat pipes 6 opposite the evaporation zone 10 are fluidly connected to each other, so that a fluid transition between the heat pipes 6 in the region of the condensation zones of the heat pipes 6 is also provided. In principle, this cavity 11, and in particular the condensation zones connecting the heat pipes 6 to each other, is not necessarily required. This is connected with the fact that the heat pipes 6 are formed as microchannels in the vertical fins 3, so that the heat pipes 6 are acted upon over their entire length by the air flow passing through the heat sink 1 and therefore have a condensation zone distributed practically over their entire vertical length.

[0027] FIG. 2 shows that the heat sink 1, and in particular its air heat exchanger 2, is made according to the principle of a microchannel heat exchanger, in which the vertical fins 3 extending in the direction of air flow through the heat exchanger over the entire depth of the heat sink 1 have a plurality of directly adjacent but fluidically mutually separated microchannels 7 each forming a heat pipe, so that each fin 3 in fact has a plurality of heat pipes.

[0028] The embodiment of Fig. 3 shows an assembly including a further embodiment of a heat sink 1 mounted via its mounting surface 9 to an IT component 100 to be cooled, e.g. a CPU chipset. A radial fan 12 is configured to generate a flow of a volume of air through the heat sink 1 in the direction of the arrows. The radial fan 12 may be attached to an air heat exchanger 2 via a mounting flange 13.

[0029] The features of the invention disclosed in the above description, in the drawings and in the claims may be essential for implementing the invention both individually and in any combination. [Explanation of symbols]

[0030] 1 Heatsink 2. Air heat exchanger 3. Fin 4 More Fins 5 Air Induction Channel 6 Heat Pipes 7. Microchannel 8 Working medium 9 Mounting surface 10 Evaporation Zone 11 Cavity 12 Airflow Generator 100 Electronic Components

Claims

1. A heat sink (1) for an electronic component (100), the heat sink (1) having an air heat exchanger (2) provided with a number of fins (3, 4) which delimit an air duct (5) passing through the air heat exchanger (2), the fins (3, 4) being at least partially in the form of a heat pipe (6).

2. 2. The heat sink (1) according to claim 1, wherein the fins (3, 4) in the form of heat pipes (6) each have at least one vertical hollow conductor or microchannel (7) through which the working medium (8) of the heat pipe (6) is guided.

3. 3. The heat sink (1) according to claim 1 or 2, wherein the air heat exchanger (2) is a microchannel heat exchanger, preferably without forward and reverse flow, having a closed volume of working medium (8).

4. 4. The heat sink (1) according to claim 3, wherein each microchannel (7) of the microchannel heat exchanger is one of the heat pipes (6).

5. 5. The heat sink (1) according to claim 3 or 4, wherein the microchannel heat exchanger has an evaporation zone (10) into which first ends of the microchannels (7) open and through which the microchannels (7) are fluidly connected to one another.

6. 6. The heat sink (1) of claim 5, wherein the evaporation zone (10) is in thermal contact with a mounting surface (9) of the heat sink (1) for mounting the heat sink (1) to an electronic component (100) to be cooled.

7. The heat sink (1) according to any one of claims 3 to 6, wherein the microchannel heat exchanger has a cavity (11) into which the microchannels (7) open at a second end arranged opposite the first end.

8. The heat sink (1) according to any one of claims 3 to 7, wherein the microchannel heat exchanger has, in addition to the fins (3) formed as heat pipes (6), further fins (4) which extend substantially parallel to each other, are spaced apart from each other and extend substantially perpendicular to the fins (3) formed as heat pipes (6).

9. 9. The heat sink (1) according to claim 8, wherein the further fins (4) are in the form of solid fins made of a thermally conductive material, and adjacent fins (3) in the form of heat pipes (6) are thermally coupled to each other via a plurality of further fins (4).

10. The heat sink according to any one of the preceding claims, wherein the fins (3) in the form of heat pipes (6) run parallel to one another and are spaced apart from one another by less than 10 mm, preferably less than 8 mm, particularly preferably less than 6 mm.

11. The heat sink (1) according to any one of claims 1 to 10, wherein the fins (3) in the form of heat pipes (6) each have a plurality of vertical and parallel microchannels (7) arranged one behind the other in the longitudinal direction of the fins (3) in the form of heat pipes (6).

12. 12. An assembly comprising at least one heat sink (1) according to any one of claims 1 to 11 and an electronic component (100), wherein the heat sink (1) is arranged in thermal contact with the electronic component (100) and the heat pipe (6) has vertical hollow conductors or microchannels (7) which extend at least partially perpendicular and orthogonal to the electronic component (100).

13. 13. The assembly according to claim 12, wherein the heat sink (1) is in thermal contact with the electronic component (100) via a mounting surface of the heat sink (1), which is the thermally coupled side of the evaporation zone (10) of the heat pipe (6).

14. Assembly according to claim 13, wherein the heat sink (1) has, on its outer side opposite the evaporation zone (10), a cavity (11) into which the vertical hollow conductors or microchannels (7) of the heat pipes (6) open.

15. Assembly according to any of claims 12 to 14, comprising an airflow generator (12), preferably a fan, by means of which air is transported through the air conducting channels (5) and around the fins (3, 4) in the form of heat pipes (6).

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