TECHNICAL FIELD

The present disclosure relates to cooling technology, in particular to a cooling apparatus for cooling electronic components and an electronic apparatus comprising such a cooling apparatus.

BACKGROUND

Electronic components generate heat when an electric current flows through them. The amount of heat depends on the power, device characteristics, and circuit design. The electrical resistance of processors, driver circuits, power circuits, and memory contribute to some heat and power losses. To avoid failures or circuit malfunctions, electronic components must operate and remain within safe temperature limits. While some circuits will work without additional cooling, most circuits require mechanisms for dissipating heat and cooling.

SUMMARY

It is an objective to provide an improved cooling apparatus for cooling electronic components as well as an electronic apparatus comprising such an improved cooling apparatus.

The foregoing and other objectives are achieved by the subject matter of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

According to a first aspect, a cooling apparatus for cooling one or more electronic components, such as electronic chips or microprocessors is provided.

The cooling apparatus comprises a base plate having a front wall, a rear wall and a base plate cavity defined between the front wall and the rear wall. In use, the rear wall of the base plate is configured to be in thermal contact with the one or more electronic components to be cooled. The base plate may be made from metal, in particular aluminum or an aluminum alloy.

Moreover, the cooling apparatus comprises a plurality of cooling fins, wherein each cooling fin defines a cooling fin cavity and is attached to the front wall of the base plate such that the cooling fin cavity is fluidly connected with at least a portion of the base plate cavity. Each cooling fin may be made from metal, in particular aluminum or an aluminum alloy. The cooling fin cavity may comprise a plurality of meandering cooling channels.

The base plate and each of the plurality of cooling fins define a respective loop heat pipe, LHP, configured to circulate a cooling agent, wherein the cooling agent comprises a liquid phase cooling agent and a vapor phase cooling agent. The LHP comprises a LHP evaporation zone (also referred to as LHP evaporator) inside the base plate cavity, wherein the LHP evaporation zone is configured to convert the liquid phase cooling agent into the vapor phase cooling agent, i.e. to evaporate the liquid phase cooling agent. Moreover, the LHP comprises a LHP compensation zone (also referred to as LHP reservoir) inside the respective cooling fin, wherein the LHP compensation zone is configured to accumulate the condensed liquid phase cooling agent and to supply the cooling agent back to the LHP evaporator. The LHP further comprises a wick element(also referred to as wick structure) arranged inside the base plate cavity to extend at least partially between the LHP evaporation zone and the LHP compensation zone and configured for separating the LHP evaporation zone from the LHP compensation zone and to absorb and transport liquid cooling agent. The wick element may comprise a metal powder, for instance, an aluminum alloy powder, a pure aluminum powder, a copper powder and the like. Thus, an improved cooling apparatus is provided enabling an efficient cooling of electronic components by means of a LHP cooling circuit. The improved cooling apparatus has a lower thermal resistance and, hence, a more even temperature distribution along the base plate and the cooling fins, thereby providing an easier path for the heat flux from the electronic components, through the cooling apparatus and, finally, to the cooling air. Thus, for a given size of the cooling apparatus, by reducing the thermal resistance of the cooling apparatus the electronic components may be cooled more efficiently.

In a further possible implementation form, the LHP compensation zone is defined by the cooling fin cavity and arranged, in use of the apparatus, at a smaller height than the LHP evaporation zone, wherein the wick element is configured to transport against gravity by capillary action the liquid cooling agent from the LHP compensation zone to the LHP evaporation zone. In other words, in an implementation form, the wick element is arranged and configured to create a capillary pressure causing a pressure difference between the LHP evaporation zone and the LHP compensation zone forcing the liquid cooling agent to move upwards against the force of gravity from the LHP compensation zone to the LHP evaporation zone.

In a further possible implementation form, each cooling fin or the front wall of the base plate further comprises a partitioning wall arranged between a portion of the cooling fin cavity and a portion of the base plate cavity for dividing a least a portion of the LHP compensation zone from at least a portion of the LHP evaporation zone.

In a further possible implementation form, the LHP further comprises a cooling agent line fluidly connecting the LHP evaporation zone with the LHP compensation zone. In other words, in an implementation form, the LHP comprises a cooling agent line for providing a fluidic connection between the LHP evaporation zone and the LHP compensation zone for the vapor cooling agent generated in the LHP evaporation zone.

In a further possible implementation form, the LHP compensation zone is located in a portion of the cooling agent line and arranged, in use of the apparatus, at a greater height than the LHP evaporation zone, wherein the wick element is configured to absorb liquid cooling agent from the LHP compensation zone and to prohibit a transport of vapor cooling agent from the LHP evaporation zone to the LHP compensation zone via the wick element.

In a further possible implementation form, the cooling agent line is defined by one or more internal channels of each of the plurality of cooling fins.

In a further possible implementation form, a portion of the cooling agent line is arranged, in use of the apparatus, at a smaller height than the cooling fin cavity, in particular than a bottom portion of the cooling fin cavity.

In a further possible implementation form, the LHP further comprises at least one further wick element, wherein the at least one further wick element is arranged on at least a portion of an inside surface of the cooling agent line and fluidically connected to the wick element arranged inside the base plate cavity so that liquid cooling agent is exchanged between the further wick element and the wick element arranged inside the base plate cavity.

In a further possible implementation form, each cooling fin cavity comprises a plurality of meandering cooling channels configured to guide the flow of vapor and liquid cooling agent in the cooling fin cavity. Portions of the plurality of meandering cooling channels are separated by material portions of each cooling fin, which mechanically strengthen each cooling fin to withstand a wide range of operation pressures, i.e. below and above ambient pressure levels.

In a further possible implementation form, the plurality of meandering cooling channels of each cooling fin cavity defines a LHP condensation zone configured to convert the vapor phase cooling agent into the liquid phase cooling agent. In a further possible implementation form, the plurality of cooling fins comprises a plurality of roll bonding cooling fins. In other words, in an implementation form, the cooling fins are manufactured using a roll bonding process.

In a further possible implementation form, the wick element comprises a porous metallic structure. In an implementation form, the porous metallic wick element may be made from a metallic powder, metallic fiber, metallic mesh or combinations thereof.

In a further possible implementation form, the wick element is arranged within the base plate cavity in contact with the rear wall of the base plate, wherein the rear wall of the base plate is configured to be in contact with the one or more electronic components. A portion of the wick element in the evaporation zone may be in contact with both the front wall and the rear wall of the base plate.

According to a second aspect an electronic apparatus is provided, comprising one or more electronic components and a cooling apparatus according to the first aspect for cooling the one or more electronic components. The electronic apparatus may comprise, for instance, an electronic telecommunications apparatus, such as an antenna, a receiver, a radio remote unit, RRU, a massive MIMO unit, and the like.

Details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, embodiments of the present disclosure are described in more detail with reference to the attached figures and drawings, in which:

Fig. 1 is a perspective, partially exploded view of a cooling apparatus according to an embodiment for cooling electronic components;

Fig. 2 is a perspective view of the cooling apparatus of figure 1 with air flowing through the space between a plurality of cooling fins and a base plate of the cooling apparatus;

Fig. 3a is a cross-sectional view of a cooling fin and the base plate of the cooling apparatus of figures 1 and 2 according to an embodiment;

Fig. 3b schematically illustrates the flow of liquid cooling agent and vapor cooling agent within the cooling fin and the portion of the base plate shown in figure 3a; Fig. 4a is a cross-sectional view of a cooling fin and the base plate of the cooling apparatus of figures 1 and 2 according to a further embodiment;

Fig. 4b schematically illustrates the flow of liquid cooling agent and vapor cooling agent within the cooling fin and the portion of the base plate shown in figure 4a;

Fig. 5a is a cross-sectional view of a cooling fin and the base plate of the cooling apparatus of figures 1 and 2 according to a further embodiment; and

Fig. 5b schematically illustrates the flow of liquid cooling agent and vapor cooling agent within the cooling fin and the portion of the base plate shown in figure 5a.

In the following, identical reference signs refer to identical or at least functionally equivalent features.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following description, reference is made to the accompanying figures, which form part of the disclosure, and which show, by way of illustration, specific aspects of embodiments of the present disclosure or specific aspects in which embodiments of the present disclosure may be used. It is understood that embodiments of the present disclosure may be used in other aspects and comprise structural or logical changes not depicted in the figures. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present disclosure is defined by the appended claims.

Figure 1 is a perspective view of a cooling apparatus 100 according to an embodiment for cooling electronic components or electronic equipment 200, 210 of an electronic apparatus. In the embodiment shown in figure 1 the electronic components comprise a printed circuit board 200 with a plurality of electronic chips 210, wherein the printed circuit board 200 and the electronic chips 210 are attached to the cooling apparatus 100. The plurality of electronic chips 210 may comprise a CPU, an electronic memory, a communication interface and the like. The electronic apparatus comprising the one or more electronic components 200, 210 and the cooling apparatus 100 may be, for instance, an electronic telecommunications apparatus, such as an antenna, a receiver, a radio remote unit, RRU, a massive MIMO unit, and the like.

The cooling apparatus 100 comprises a base plate 110 and a plurality of cooling fins 120a-n. As will be described in more detail below in the context of figures 3a-5a and 3b-5b, the base plate 110 comprises a front wall or front portion 110a, a rear wall or rear portion 110b and a base plate cavity 110c defined between the front wall 110a and the rear wall 110b of the base plate 110. As can be taken from figure 2, the plurality of cooling fins 120a-n, which in the embodiments shown in the figures 3a-5a and 3b-5b are implemented as plates having a kind of preferred P-shaped profile, are attached to the front wall 110a of the base plate 110, which may have a substantially rectangular shape.

In an embodiment, the front wall 110a of the base plate may comprise a plurality of slits or opening for receiving the plurality of cooling fins 120a-n. The plurality of electronic components 200, 210 are attached to the rear wall 110b of the base plate 110. Thus, in use, the rear wall 110b of the base plate 110 is configured to be in thermal contact with the one or more electronic components 200, 210 to be cooled. In an embodiment, the front wall 110a and/or the rear wall 110b of the base plate 110 may be made from metal, in particular aluminum or aluminum alloy. Likewise, the plurality of cooling fins 120a-n may be made from metal, in particular aluminum or an aluminum alloy. In an embodiment, the plurality of cooling fins 120a-n comprise a plurality of roll bonding cooling fins 120a-n, i.e. a plurality of cooling fins 120a-n manufactured using a roll bonding process.

Figure 3a is a cross-sectional view of a cooling fin 120a and of the base plate 110 of the cooling apparatus 100 of figures 1 and 2 according to an embodiment. Figure 3b schematically illustrates the flow of liquid cooling agent (indicated with solid arrows) and vapor cooling agent (indicated with dashed arrows) within the cooling fin 120a and the portion of the base plate 110a for the embodiment shown in figure 3a. As can be taken from figure 3a, which illustrates a cross-section of the cooling fin 120a as an example for the plurality of cooling fins 120a-n attached to the base plate 110, the exemplary cooling fin 120a defines a cooling fin cavity 124 with a plurality of meandering cooling channels and is attached to the front wall 110a of the base plate 110 such that the cooling fin cavity 124 with the plurality of meandering cooling channels is fluidly connected with at least a portion of the base plate cavity 110c.

As will be described in more detail below, in particular in the context of figure 3b, the base plate 110 and the exemplary cooling fin 120a define a loop heat pipe, LHP, i.e. a cooling circuit configured to circulate a cooling agent, wherein the cooling agent comprises a liquid phase cooling agent and a vapor phase cooling agent. In an embodiment, the cooling agent may be a refrigerant liquid.

The LHP comprises a LHP evaporation zone (also referred to as LHP evaporator and indicated by the letter “A” in figures 3a-5a, 3b-5b) inside the base plate cavity 110c. The LHP evaporation zone A is configured to convert the liquid phase cooling agent into the vapor phase cooling agent, i.e. to evaporate the liquid phase cooling agent. Moreover, the LHP comprises a LHP compensation zone (also referred to as LHP reservoir and indicated by the letter “B” in figures 3a-5a, 3b-5b), which in the embodiments shown in figures 3a, b is located inside the cooling fin cavity 124 with the plurality of meandering cooling channels, in particular at a bottom portion of the cooling fin cavity 124. The LHP compensation zone B is configured to accumulate the condensed liquid phase cooling agent and to supply the liquid phase cooling agent back to the LHP evaporation zone A. The LHP further comprises a wick element (also referred to as wick structure) 122a, 122b arranged inside the base plate cavity 110c to extend at least partially between the LHP evaporation zone A and the LHP compensation zone B for dividing the LHP evaporation zone A from the LHP compensation zone B. In the embodiment shown in figures 3a and 3b, in particular the wick element portion 122b extends between the LHP evaporation zone A and the LHP compensation zone B for dividing the LHP evaporation zone A from the LHP compensation zone B. In an embodiment, the wick element 122a, b comprises a porous metallic structure. In an embodiment, the porous metallic wick element 122a, b may be made from a metallic powder, metallic felt, metallic mesh and/or combinations thereof.

In the embodiment shown in figures 3a, b, the LHP evaporation zone A is arranged, in use of the apparatus 100, at a greater height than the LHP compensation zone B. In this embodiment, as can be taken from figure 3b, which indicates the flow of the liquid cooling agent by solid arrows and the flow of the vapor cooling agent by dashed arrows, the wick element 122a, b is configured to transport by capillary action the liquid cooling agent accumulated in the LHP compensation zone B, i.e. at the bottom of the cooling fin cavity 124, against gravity upwards to the LHP evaporation zone A. In other words, in the embodiment shown in figures 3a, b, the wick element 122a,b is arranged and configured to create a capillary pressure causing a pressure difference between the LHP evaporation zone A and the LHP compensation zone B forcing the liquid cooling agent to move upwards against the force of gravity from the LHP compensation zone B to the LHP evaporation zone A along the wick element portion 122a.

As illustrated in figures 3a, b, the wick element portions 122a,b may be arranged within the base plate cavity 110c in contact with the rear wall 110b of the base plate 110 and partly in contact with the front wall 110a, wherein, as already described above, the electronic components 200, 210 are attached to and, thus, are in thermal contact with the rear wall 110b of the base plate 110. Due to this arrangement of the wick element 122a, b within the base plate cavity 110c the liquid cooling agent rising due to the capillary pressure in the wick element 122a,b efficiently absorbs heat generated by the electronic components 200, 210. This heat absorption, in turn, results in the evaporation of the heated liquid cooling agent in the wick element 122a into the evaporation zone, as schematically indicated in figure 3b.

As illustrated in figures 3a, b, the LHP defined by the exemplary cooling fin 120a and the base plate 110 further comprises a cooling agent line 123a-d fluidly connecting the LHP evaporation zone A with the LHP compensation zone B. As will be appreciated and as illustrated in figure 3b, the cooling agent line 123a-d provides a fluidic connection between the LHP evaporation zone A and the LHP compensation zone B for the vapor cooling agent generated within the LHP evaporation zone A. In the embodiment shown in figures 3a, b the cooling agent line 123a- d between the LHP evaporation zone A and the LHP compensation zone B is defined by one or more internal channels 123a-d of the exemplary cooling fin 120a.

In the embodiment shown in figures 3a, b, the cooling agent line 123a-d defined by the cooling channel 123a-d of the exemplary cooling fin 120a comprises a first channel portion 123a extending at a first height horizontally away from the LHP evaporation zone A, a second channel portion 123b extending vertically downwards to a second height, a third channel portion 123c extending at the second height over a short horizontal direction for providing a reversal of the flow direction, and a fourth channel portion 123d extending from the second height vertically upwards for guiding the vapor cooling agent generated by the LHP evaporation zone A to the cooling fin cavity 124 of the exemplary cooling fin 120a. Thus, in an embodiment, at least one portion, in particular the third channel portion 123c of the cooling agent line 123a- d is arranged, in use of the cooling apparatus 100, at a smaller height than the cooling fin cavity 124 with the plurality of meandering cooling channels. As will be appreciated, the cooling agent line fluidly connecting the LHP evaporation zone A with the LHP compensation zone B may have a different shape and/or a different number of portions than the cooling agent line 123a- d shown in the figures. In an embodiment, each cooling fin 120a-n may also comprise more than one cooling agent line fluidly connecting the LHP evaporation zone A with the LHP compensation zone B. As will be further appreciated, the generally P-shaped profile of the exemplary cooling fin 120a allows for a more efficient usage of the bottom portion of the cooling fin 120a, which is located at a smaller height than the cooling fin cavity 124 with the plurality of meandering cooling channels.

As can be taken from figures 3a, b, the cooling fin cavity 124 of exemplary cooling fin 120a comprises a plurality or network of mutually connected meandering cooling channels. This network of mutually connected meandering cooling channels of the cooling fin cavity 124 may be defined by a plurality of material portions 126 of the roll-bonded material of the exemplary cooling fin 120a, which help to prevent an expansion or a shrinkage of the cooling fin cavity 124, when in use of the cooling apparatus 100 the operation pressure inside the cooling fin cavity 124 can be in a range, above and below the ambient pressure level. The network of mutually connected meandering cooling channels of the cooling fin cavity 124 defined by the material portions 126 of the exemplary cooling fin 120a is configured to guide the flow of vapor cooling agent in the cooling fin cavity 124 in a meandering manner. In the embodiments shown in the figures, the plurality of material portions 126 have, by way of example, a substantially hexagonal outline or cross section (may be circular to) for defining a honey-comb like pattern of material portions 126, which, in turn, defines the network of mutually connected meandering cooling channels of the cooling fin cavity 124. As will be appreciated in use, the plurality of material portions 126 together with the plurality of meandering cooling channels formed between the material portions 126 absorb a portion of the heat of the vapor cooling agent flowing upwards into the cooling fin cavity 124 via the cooling agent line 123a-d. This heat is thermally conducted via the material portions 126 and the meandering cooling channels walls to the outer surfaces of the exemplary cooling fin 120a, which are cooled by air moving along the outer surfaces of the exemplary cooling fin 120a, as schematically illustrated in figure 2. As will be appreciated and described in more detail below, some heat dissipation will also occur in the cooling agent line defined by the channels 123a-d.

Due to the heat dissipation via the inner surfaces of the cooling fin 120a the vapor cooling agent flowing upwards within the plurality of meandering cooling channels of the cooling fin cavity 124 releases heat energy outwards to the ambient air and, thus, condenses into the liquid cooling agent. Thus, the plurality of meandering cooling channels of the cooling fin cavity 124 of the exemplary cooling fin 120a can be considered to define a LHP condensation zone C configured to convert the vapor phase cooling agent into the liquid phase cooling agent. As illustrated in figure 3b, the liquid phase cooling agent generated in the LHP condensation zone C accumulates at the bottom of the cooling fin cavity 124, i.e. within the LHP compensation zone B.

As indicated in figure 3b, some vapor cooling agent may condensate already flowing through the vertically upwards extending fourth channel portion 123d of the cooling agent line 123a-d and accumulate at the bottom of the vertically upwards extending fourth channel portion 123d, i.e. within the third channel portion 123c. Thus, as indicated in figure 3b, also the vertically upwards extending fourth channel portion 123d guiding the vapor cooling agent generated by the LHP evaporation zone A to the cooling fin cavity 124 with the plurality of meandering cooling channels may be considered to define a further portion of the LHP condensation zone C.

In order to efficiently transport the liquid cooling agent accumulating within the third channel portion 123c and at the bottom of the cooling fin cavity 124 to the wick element 122a,b arranged within the base plate cavity 110c, the exemplary cooling fin 120a and, thus, the LHP may further comprise at least one further wick element 122c, d. In the embodiment shown in figures 3a, b, the at least one further wick element 122c,d is arranged on an inside surface of the vertically upwards extending fourth channel portion 123d and a bottom surface of the cooling fin cavity 124. As schematically indicated in figures 3a, b the at least one further wick element 122c, d is fluidically connected to the wick element 122a, b arranged inside the base plate cavity for transporting the liquid cooling agent from the LHP condensation zone C and the LHP compensation zone B into the wick element 122a,b arranged within the base plate cavity 110c.

As illustrated in figures 3a, b, in an embodiment the exemplary cooling fin 120a may further comprise a partitioning wall 125 arranged and extending between a portion of the cooling fin cavity with the plurality of meandering cooling channels 124 and a portion of the base plate cavity 110c. In a further embodiment, the partitioning wall 125 may be a portion of the front wall 110a of the base plate 110.

Further embodiments of the exemplary cooling fin 120a and the base plate 110 are shown in figures 4a, b and figures 5a, b. In the following primarily the differences between the embodiments of the exemplary cooling fin 120a and the base plate 110 shown in figures 4a, b and figures 5a, b and the embodiment shown in figures 3a, b will be described in more detail. As can be taken from figures 4b and 5b, a first main difference is that in the embodiments of the exemplary cooling fin 120a and the base plate 110 shown in figures 4a, b and figures 5a, b the flow directions of the vapor cooling agent and the liquid cooling agent are generally reversed in comparison with the embodiment shown in figures 3a, 3b.

Moreover, it will be appreciated, that in the embodiments of the exemplary cooling fin 120a and the base plate 110 shown in figures 4a, b and figures 5a, b the LHP compensation zone B is arranged, in use of the cooling apparatus 100, at a greater height than the LHP evaporation zone A. More specifically, as indicated, in the embodiments of the exemplary cooling fin 120a and the base plate 110 shown in figures 4a, b and figures 5a, b the LHP compensation zone B is primarily defined within the first horizontally extending channel portion of the cooling agent line 123a-d defined in the upper portion of the exemplary cooling fin 120a. Thus, as can be taken from figures 4b and 5b, in these embodiments the wick element 122a,b is configured to absorb liquid cooling agent from the LHP compensation zone B located within the first horizontally extending channel portion of the cooling agent line 123a-d and thereby prohibits a transport of vapor cooling agent from the LHP evaporation zone A to the LHP compensation zone B via the wick element. Due to this blocking effect of the wick element 122a,b the vapor cooling agent generated in the LHP evaporation zone A flows through the cooling fin cavity 124 with the plurality of meandering cooling channels and the cooling agent line 123a-d back to the LHP compensation zone B. The cooling fin cavity 124 with the plurality of meandering cooling channels and the channels 123a-d are arranged so that at least some of the vapor cooling agent is condensed in the cooling agent line portion 123a.

In the embodiment shown in figures 4a, b there is no further wick element 122c, d as in the embodiment shown in figures 3a, b. In the embodiment shown in figures 5a, b the further wick element 122c,d is provided on the inner surfaces of the horizontally extending first channel portion 123a and second vertically downwards extending channel portion 123b of the cooling agent line 123a-d. As already described above in the context of figures 1 and 2, the plurality of cooling fins 120a- n are inserted in the front wall 110a of the base plate 110, for instance, in suitably dimensioned slits thereof. In an embodiment, the wick element portions 122a, b shown in figures 3a, b, 4a, b and 5a, b may extend through the whole base plate cavity 110c and, thereby, provide the wick element for all cooling fins 120a-n. In a further embodiment, the base plate cavity 110c may be partitioned by internal walls into a plurality of compartments, wherein the wick element of each compartment provides the wick element 122a, b for one or more cooling fins 120a-n. In an embodiment, these compartments may have different sizes and, thus, provide the wick element for a different number of cooling fins.