WO2023035172A1

WO2023035172A1 - A heatsink fin, a heatsink provided therewith, a heat exchange arrangement provided with the heat sink and method of manufacturing a heatsink fin

Info

Publication number: WO2023035172A1
Application number: PCT/CN2021/117380
Authority: WO
Inventors: Haijiang Wang; Shuaijun Li; Stevin Van WYK; Tomas Muld; Lena ELMFELDT; Elisabet Alduren; Amy HAO
Original assignee: Telefonaktiebolaget Lm Ericsson (Publ)
Priority date: 2021-09-09
Filing date: 2021-09-09
Publication date: 2023-03-16

Abstract

The disclosure relates to a heatsink fin (201, 301) to be attached to a side (252a) to a heatsink (200) base portion (250). The heatsink fin (201, 301) comprises an envelope defining a cavity (204), a first wall portion (206a) attached to said side (252a) of the base portion (250), and a plurality of dividing walls (208) that sealingly divide the cavity (204) into a plurality of sub-cavities (210). The first wall portion (206a) extends along a longitudinal direction (220) of the heatsink fin (201). Each dividing wall (208) attaches to said first wall portion (206a) at a first respective level (L1) along the longitudinal direction (220), extends towards an opposite second wall portion (206b) and attaches to the second wall portion (206b) at a respective second level (L2) along the longitudinal direction (220). The disclosure further relates to a heatsink (200) and a manufacturing method (400) of a heatsink fin (201).

Description

A heatsink fin, a heatsink provided therewith, a heat exchange arrangement provided with the heat sink and method of manufacturing a heatsink fin

TECHNICAL FIELD

The present disclosure relates to a phase change heatsink fin arranged to be attached to a heatsink, a heatsink provided with a heatsink fin, a heat exchange arrangement and a method of manufacturing a heatsink fin. More specifically, the disclosure relates to a heatsink fin arranged to be attached to a heatsink, a heatsink provided with a heatsink fin, a heat exchange arrangement and a manufacturing method of a heatsink as defined in the introductory parts of claim 1, claim 6, and claim 13.

BACKGROUND

Heatsinks for the cooling of electric components are well known. Such heatsinks may comprise a base portion aimed to be in contact with the electric component on one side and cooling the heatsink fins mounted an opposite side of the base portion. The heatsink fins may be hollow and be partly filled with a cooling liquid. During operation, parts of the cooling liquid will be evaporated, whereby the vapor, when getting in contact with an inner wall or upper part of the heatsink fin, will condense back to its liquid state. In some applications the side on which the base portion is in contact with the electric component extend in a vertical direction. The heatsink fins may extend correspondingly in the vertical direction.

As a result, a lower part of the base portion, which is in contact with a lower part of the electric component, will be primarily cooled by the cooling liquid in its liquid state, while an upper part of the base portion, which is in contact with an upper part of the electric component, is cooled by the cooling liquid in its gaseous state. The cooling performance of the heat sink will thus be different for the lower part in comparison to the upper part of the heat sink, and the cooling of the upper part of the electric component will be different, and normally inferior, to the cooling of the lower part.

Hence, there is a need for improving the cooling performance of heat sink arrangements.

SUMMARY

It is an object of the present disclosure to mitigate, alleviate or eliminate one or more of the above-identified deficiencies and disadvantages in the prior art and solve at least the above mentioned problem.

According to a first aspect there is provided a heatsink fin arranged to be attached to a first side of a heatsink base. The heatsink fin comprises an envelope defining a cavity, afirst wall portion attached to the side of the heatsink base, and a plurality of dividing walls that sealingly divide the cavity into a plurality of sub-cavities. The first wall portion extends substantially along a longitudinal direction of the heatsink fin, and each dividing wall is attached to the first wall portion at a first respective level along the longitudinal direction, and extends to an opposite second wall portion and is attached to the second wall portion at a second respective level along the longitudinal direction. The second respective level is different than the first respective level. When such a heatsink fin is applied to a heatsink, which in its turn is arranged so as to cool a non-horizontal, or generally vertical surface of heat-generating element, and the first level of each respective dividing wall is lower than the second level thereof, the cooling liquid may be provided in each respective sub-cavity, resulting in more even distribution of cooling liquid in the vertical direction, from bottom to top of each heatsink fin. The result is a more even cooling in the vertical direction.

According to some embodiments, aline of sight extending from the first level to the second level of each respective dividing wall may have an angle of about 20-70° in relation said longitudinal direction In some case, according to some embodiments, each dividing wall may have an angle with the range of about 20-45° in relation to the longitudinal direction of the heatsink fin. Furthermore, in some embodiments, each dividing wall may have an angle with the range of about 45-70° in relation to the longitudinal direction of the heatsink fin.

Having the dividing walls slanted at a certain angle is advantageous since the slanted dividing wall improve the cooling efficiency. For example, if the angle is relatively steep, e.g. about 20-45° in relation to the longitudinal direction of the heatsink fin, and the longitudinal direction of the heatsink fin is substantially vertical, the refrigerant is gathered closer to the first side of the heatsink fin which is in contact with the heat source. When a larger portion of the first wall portion will be covered with refrigerant, the cooling efficiency is improved,

In another example, if the angle is relatively flat, having a gentle slope, e.g. about 45-70°, in relation to the longitudinal direction of the heatsink fin, and the longitudinal direction of the heatsink fin is substantially vertical, the refrigerant will be more evenly distributed along the first side of the heatsink fin in contact with the heat source.

Each dividing wall serves to position the liquid refrigerant toward the side of the heatsink fin facing the heat source, improving the cooling efficiency of the heatsink fin. In other words, in order to optimize the cooling efficiency using a certain amount of refrigerant, the geometry of each sub-cavity may be based on the on, the distance between said dividing walls, the distance between the first wall portion and the second wall portion and/or the angle of each dividing wall in relation to the longitudinal direction of the heatsink fin and/or the angle of each dividing wall in relation to the vertical direction of the heatsink fin.

According to some embodiments each dividing wall may comprises at least a first part and second part. The first part is attached to the first wall portion at the first respective level, and has an angle within the range of about 20-90° in relation to the longitudinal direction of the heatsink fin, and the second part is attached to the second wall portion at the second respective level, and has an angle within the range of about 20-70° in relation to the longitudinal direction of the heatsink fin. The angle between the first part and the longitudinal direction is different than the angle between the second part and the longitudinal direction.

According to some embodiments each dividing wall may further comprises a third dividing wall part, attached between the first part and the second part, and having an angle within the range of about 0-70° in relation to the longitudinal direction of the heatsink fin. The angle between second part and the longitudinal direction is different than the angle between the third part and the longitudinal direction. It is advantageous to have a dividing wall comprising at least two parts, since it combine the effects of having both a relatively steep dividing wall which gather the liquid refrigerant closer to the first side of the heatsink fin, which is in contact with the heat source, and a relatively flat dividing wall which obtain a more evenly distribution of the refrigerant along the first side of the heatsink fin in contact with the heat source. Another advantage is that the two volumes within each sub-cavity, the boiling volume, i.e. the volume comprising refrigerant, and the condensation volume, i.e. the volume not comprising refrigerant, can be designed with respect to a certain environment. For example, the longitudinal direction of the heatsink fin may be angled in relation to a vertical direction, and each sub-cavity and the comprising boiling volume and condensation volume may be designed accordingly due to gravity affecting the refrigerant and the phase change heat transfer process.

According to some embodiments the envelope may be defined a cuboid comprising three pairs of opposite walls. In other words, the heatsink fin may have the shape of a three-dimensional rectangle.

According to a second aspect there is provided a heatsink comprising a heatsink base, comprising a first side and an opposite second side. The first side of the heatsink base is configured to be in contact with at least one heat source. The at least one heatsink fin is a heatsink fin according to the first aspect, and the heatsink fin is mounted on the second side of the heatsink base.

According to some embodiments, for each individual dividing wall, said first respective level may be arranged to be located at a lower level compared to the second respective level, such that the refrigerant is gathered in a lower part of each sub-cavity.

According to some embodiments, the heatsink fin may be arranged so that said longitudinal direction of the heatsink fin is parallel with a vertical plane, such that the refrigerant is gathered in a lower part of each sub-cavity.

According to some embodiments, said first side of the heatsink, which is in contact with the heat source, may extend in the vertical plane. It is advantageous to have a long heatsink fin extending in the vertical plan. It enables the heatsink fin to cover a long heat source, or a long part of an object having heat sources distributed along a vertical direction. In other words, the length of the heatsink fin can be constructed in accordance with the length of the heat source to be cooled. This is advantageously, since the heatsink may maximize its surface area in contact with the heat source and/or enable more heatsink fins to be mounted on the heatsink base, both leading to an improved heat transferring process of the heat exchange arrangement.

According to some embodiments, the heatsink further may comprise at least two heatsink fins, which are mounted parallel to each other and evenly distributed around the second side of the base portion. This is advantageously, since more heatsink fins further improve the cooling efficiency of the heatsink and thereby improve the cooling efficiency of the whole exchange arrangement system

According to some embodiments, each sub-cavity may be configured to be filled with refrigerant up to a minimum level so that said refrigerant covers the first wall portion which is in contact with the heat source. Having the amount of refrigerant such that said refrigerant covers the first wall portion which is in contact with the heat source is advantages since is improve the cooling efficiency of the whole exchange arrangement system. For example, when the exchange arrangement system is active, i.e. cooling a heat source by transferring heat from a heat source, some of the filled refrigerant will start boiling and evaporate in to a condensation volume. This mean that the amount of liquid refrigerant will decrease. By ensuring that the level of the refrigerant will not decrease to a level, not covering the whole first wall portion which is in contact with the heat source, the refrigerant may be filled up to a minimum level, taking the evaporation of refrigerant into consideration. If the minimum level of refrigerant is not fulfilled, it will cause that the components’ temperature at the upper side of a sub-cavity to be too high. For example, the minimum level may be based on the heat and/or heat flow from said heat source, and/or the overall heat exchange process. In other words, the minimum level of refrigerant is set so that, when some amount of the refrigerant is in gas state, the remaining refrigerant, i.e. the part of the refrigerant still in liquid state, still need to cover the first wall portion which is in contact with the heat source.

According to some embodiments, the heat source may be a radio transceiver.

According to a third aspect there is provided a manufacturing method of a heatsink according to the second aspect, each heatsink fin further comprises a filling port and interconnection channels between the sub-cavities, and wherein the assembly process of each heatsink fin comprises the following steps. Filling the sub-cavities with refrigerant via the filling port. The refrigerant is evenly distributed throughout the sub-cavities via the interconnection channels. Closing the filling port. Turning the heatsink fin 180° along the horizontal central axis, such that the refrigerant will flow to the opposite side of each sub-cavities such that the refrigerant is evenly distributed throughout the sub-cavities via the interconnection channels. Finally, closing each interconnection channel between the sub-cavies. This is advantageously since the multistage phase change heatsink fin according to the second aspect can be filled with refrigerant with only one refrigerant filling operation utilizing only one filling port design on the whole heatsink fin. This manufacturing process make manufacturing simple and therefore cost efficient.

Effects and features of the second through third aspects are to a large extent analogous to those described above in connection with the first aspect. Embodiments mentioned in relation to the first aspect are largely compatible with the second through third aspects.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects, as well as additional objects, features and advantages of the present disclosure, will be more fully appreciated by reference to the following illustrative and non-limiting detailed description of example embodiments of the present disclosure, when taken in conjunction with the accompanying drawings.

Figure 1a shows a perspective view of a heatsink according to the prior art of the present disclosure.

Figure 1b shows a cross-sectional view of a heatsink fin according to the prior art of the present disclosure.

Figure 1c shows a cross-sectional view of a heat exchange arrangement according to the prior art of the present disclosure.

Figure 2a shows a cross-sectional view of the heatsink fin according to an aspect of the present disclosure.

Figure 2b shows a cross-sectional view of the heatsink according to an aspect of the present disclosure.

Figure 3 shows a cross-sectional view of the heatsink fin according to another embodiment of the present disclosure.

Figure 4a shows a flow chart of the manufacturing process of a heatsink fin according to an embodiment of the present disclosure.

Figure 4b-4e shows a cross-sectional view of the heatsink fin during a manufacturing process according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Aspects of the present disclosure will be described more fully hereinafter with reference to the accompanying drawings. The apparatus and method disclosed herein can, however, be realized in many different forms and should not be construed as being limited to the aspects set forth herein. Like numbers in the drawings refer to like elements throughout.

The terminology used herein is for the purpose of describing particular aspects of the disclosure only, and is not intended to limit the invention. As used herein, the singular forms "a" , "an" , "the" and "said" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

In the drawings and specification, there have been disclosed exemplary embodiments. However, many variations and modifications can be made to these embodiments. Accordingly, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the embodiments being defined by the following claims.

Terminology

The terms boiling volume, evaporation volume and refrigerant reservoir, are to be interpreted as the bottom part of a heatsink fin, when the longitudinal direction of the heatsink fin arrange in a vertical direction, in which the refrigerant obtain heat and evaporate.

The terms condensation volume is to be interpreted as the upper part of a heatsink fin, when the longitudinal direction of the heatsink fin arrange in a vertical direction.

The term refrigerant, cooling liquid is/are to be interpreted as a working fluid used in the refrigeration cycle. The refrigerant may be in liquid state, as well as gas state. When the refrigerant is in liquid state it is arrange to be gathered with in a boiling volume, and when the refrigerant is in gas state it is arrange to be gathered with in a condensation volume.

The term dividing wall, is used to explain that there is a hermetic physical barrier which prevent refrigerant in one sub-cavity to be transferred to another sub-cavity. The dividing walls is therefore not limited to an extra dedicated piece of material. The dividing wall may be constituted by rolling, stamping and/or pressing two sheets of metal, forming dividing walls defining cavities. In other words, two sheets of metal can be partly pressed together, forming dividing walls which defining cavities and channels in which refrigerant can be filled.

The term sub-cavity, is used to explain a volume defined by at least two dividing walls. In others words, dividing walls can be used to create a system of channels or canals within a sub-cavity.

The present disclosure will now be described with reference to the accompanying drawings, in which preferred example embodiments of the disclosure are shown. The disclosure may, however, be embodied in other forms and should not be construed as limited to the herein disclosed embodiments. The disclosed embodiments are provided to fully convey the scope of the disclosure to the skilled person.

Fig. 1a illustrates a simplified architecture of the prior art heatsink 100. The heatsink 100 comprises a heatsink base portion 150 having a first side 152a and a second side 152b. The heatsink also comprises a plurality of a heatsink fins 101 attached to the second side 152b. The first side 152a of the heatsink 100 is arrange in contact with a heat source 130 (not shown in fig 1a) such that the heat from the heat source 130 is transferred from said heat source to said plurality of heatsink fins 101, via the first side 152a and the second side 152b.

Fig. 1b illustrates a simplified cross-section view of the prior art heatsink fin 101 of the heatsink 100 in Fig. 1a. The heatsink fin 101 is considered to have only one large connected cavity 110 through the whole heatsink fin 101, and said cavity 110 is partly filled with refrigerant 140. The refrigerant 140 will sink to a lower side of the heatsink fin 101 due to the gravity.

Fig. 1c illustrates a simplified heat exchange arrangement heat transferring process. The size of the arrow indicate the heat being transferred, i.e. the heat sources 130 covered by the refrigerant is transferring more heat.

Fig. 2a illustrates a simplified architecture of a first aspect of the disclosure. Fig. 2a illustrate a multistage phase change heatsink fin 201 (from now on referred to as heatsink fin 201) made of aluminum. The heatsink fin 201 is arranged to be attached to a first side 252a of a heatsink base portion 250 (illustrated in the figure with dashed lines) . The heatsink fin 201 comprises an envelope defining a cavity 204, afirst wall portion 206a which extends substantially along a longitudinal direction 220 of the heatsink fin 201, and is attached to the first side 252b of the base portion 250. The heatsink fin 201 also comprises plurality of dividing walls 208 that sealingly divide the cavity 204 into a plurality of sub-cavities 210. Each dividing wall 208 is attached to the first wall portion 206a at a first respective level L1 along the longitudinal direction 220 and extends to an opposite second wall portion 206b and is attached to the second wall portion 206b at a respective second level L2 along the longitudinal direction 220. The second level L2 is different than the first level L1.

In some embodiments, aline of direction extending from the first respective level L1 to the second respective level L2 of each respective dividing wall 208 has an angleαof about 20-70° in relation said longitudinal direction 220.

In some embodiments, each dividing wall 208 is angled between about 20-45° in relation to the longitudinal direction 220 of the heatsink fin 201.

In some embodiments, each dividing wall 208 is angled between about 45-70° in relation to the longitudinal direction 220 of the heatsink fin 201.

The angleαin the illustrated embodiment in Fig. 2b is about 45° in relation to the longitudinal direction 220 of the heatsink fin 201.

In some embodiments, the envelope defines a cuboid comprising three pairs of opposite walls. This three-dimensional shape of the heatsink fink is not shown in Fig. 2a.

Fig. 2b illustrates a simplified architecture of a heat exchange arrangement comprising a heat source 230, and the heatsink 200 according to a second aspect of the disclosure. The illustration is a two-dimensional cross-section view. Therefore, only one heatsink fin 201 can be seen in the figure. It is appreciated by the skilled person that said heat exchange arrangement comprises a plurality of heatsink fins 201.

Fig. 2b shows a heatsink 200 comprising a base portion 250, comprising a first side 252a and an opposite second side 252b. The second side 252b of the base portion 250 is configured to be in contact with a heat source 230 (illustrated in the figure with dashed lines) . Said heat source 230 may be any heat source for example a heat source of computers e.g. CPUs, GPUs, chipset and RAM modules, or a heat source at a radio communication product, e.g. aradio base station. In Fig. 2b, the heat source 230 is illustrated as a plurality of smaller heats sources, this is merely for illustration purpose, since the shape and size of real world heat sources may vary. The heatsink 200 also comprising a plurality of heatsink fins 201 according to the first aspect (for ease of illustration, only one heatsink fin 201 is shown in the two-dimensional drawing of Fig. 2b) . The heatsink fins 201 is mounted on the first side 252a of the heatsink base portion 250.

The heatsink 200 is configured such that the heat from said heat source 230 is transferred from the heat source 230 via the heatsink base portion 250 and the first wall portion 206a into a boiling volume, i.e. the volume of each sub-cavities 210 which is partly filled with refrigerant 240 indicated by solid parallel lines (for ease of illustration of the angleα, the solid parallel lines has been removed in the upper most sub-cavity) . The refrigerant 240 will further transfer the heat along the longitudinal direction 220 of the heatsink fin 201 up in to a condensation volume, i.e. the volume of the sub-cavity not comprising refrigerant 240. The direction of described heat flow is indicated in the figure with dashed arrows (for simplicity, only indicated in one of said sub-cavities) .

In some embodiments, for each individual dividing wall 208, said first respective level L1 is arranged to be located at a lower level compared to the second respective level L2, such that the refrigerant 240 is gathered in a lower part of each sub-cavity 210.

In some embodiment, the heatsink fin 201 is arranged so that said longitudinal direction 220 of the heatsink fin 201 is parallel with a vertical direction 220, such that the refrigerant 240 is gathered in a lower part of each sub-cavity 210. In the figure, the heatsink fin 201 is parallel with a vertical direction, which can be seen while looking at the refrigerant 240 laying in a horizontal plan and gathered in the lower part, i.e. the boiling volume, of each sub-cavity 210, due to gravity.

In some embodiments, the first side 252a of the heatsink 200, which is in contact with the heat source 230, extends in the vertical plane 222. The heatsink fins 201 (in which only one is shown) in Fig. 2b extends in the vertical plan 222 such that the length of heatsink fin 201 corresponds to the distribution of the heat source 230.

In some embodiment, the plurality of heatsink fins 201 (in which only one is shown in Fig. 2b) are mounted parallel to each other and evenly distributed around the second side 252b of the base portion 250.

In some embodiment, each sub-cavity 210 is configured to be filled with refrigerant 240 up to a minimum level so that said refrigerant 240 covers the first wall portion 252a which is in contact with the heat source 230. In Fig. 2b, it can be seen that the refrigerant 240 is covering the whole first wall portion 252a which is in contact with the heat source 230. The minimum level may be based on the heat and/or heat flow from said heat source 230, and/or the overall heat exchange process. For example, the minimum level of refrigerant 240 is set so that, when some amount of the refrigerant is in gas state, the remaining refrigerant, i.e. the part of the refrigerant still in liquid state, still need to cover the first wall portion 252a which is in contact with the heat source 230

In some embodiment, the heat source 230 is a radio transceiver.

Fig. 3 illustrates a simplified architecture of an example embodiment according to the second aspect of this disclosure. Fig. 3 show a heatsink fin 301 similar to the heatsink fin 201 in Fig. 2a-2b,except that each dividing wall 308 further comprises at least a first part 308a and second part 308b. The first part 308a is attached to the first wall portion 206a at the first respective level L1, and has a first angleβwithin the range of about 20-90° in relation to the longitudinal direction 220 of the heatsink fin 301. The second part 308a is attached to the second wall portion 206b at the second respective level L2, and has an second angle γ within the range of about 20-70° in relation to the longitudinal direction 220 of the heatsink fin 301. In the illustrated embodiment, the first angleβis about 90° and the second angle γ is about 20° in relation to the longitudinal direction 220 of the heatsink fin 201.

In some embodiment, each dividing wall 308 may further comprises a third dividing wall part 308c, attached between the first part 308a and the second part 308b, and having an third angleδwithin the range of about 0-70° in relation to the longitudinal direction 220 of the heatsink fin 301. In the illustrated example embodiment, the third angleδis about 20° in relation to the longitudinal direction 220 of the heatsink fin 201. For illustration purposes only, the third angle of some of the third dividing wall parts 308c has been angledδ’ about 90° in relation to the longitudinal direction 220 of the heatsink fin 201.

Fig. 4a illustrates a simplified architecture of an embodiment according to the third aspect of this disclosure. Fig. 4a show a flow chart for the manufacturing method of a

heatsink

201, 301 according to the second aspect. Here, each

heatsink fin

201, 301 further comprises a filling port 402. Also, each

heatsink fin

201, 301 further comprise interconnection channels 404 between the sub-cavities 210, 310. The assembly process of each

heatsink fin

201, 301 comprises the following steps.

In step S002, the sub-cavities 210 310 are filled with refrigerant 240 via the filling port 402.

In step S004, the filling port 402 is closed.

In step S006, the

heatsink fin

201, 301 is turned such that the refrigerant 240 is evenly distributed throughout the sub-cavities 210, 310 via the interconnection channels 404.

In step S008, each interconnection channel 404 between the sub-cavies 210310 are closed.

Fig. 4b-4e illustrate a simplified architecture of an embodiment according to the fourth aspect of this disclosure. Fig. 4b-4e show a cross-sectional view of the heatsink fin during a manufacturing process of a heatsink fin according to the first aspect.

The person skilled in the art realizes that the present disclosure is not limited to the preferred embodiments described above. The person skilled in the art further realizes that modifications and variations are possible within the scope of the appended claims. For example, the number of sub-cavities, size of each sub-cavity, the shape of each sub-cavities, the type of heat source, the type of refrigerant, the orientation of the heat exchange arrangement, the heatsink fins and each sub-cavity. Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed disclosure, from a study of the drawings, the disclosure, and the appended claims.

Claims

A heatsink fin (201, 301) arranged to be attached to a side (252a) to a base portion (250) of a heatsink (200) , wherein the heatsink fin (201, 301) comprises:

- an envelope defining a cavity (204) ,

- a first wall portion (206a) configured to be attached to said side (252a) of the base portion (250) , and

- a plurality of dividing walls (208) that sealingly divide the cavity (204) into a plurality of sub-cavities (210) , wherein the first wall portion (206a) extends substantially along a longitudinal direction (220) of the heatsink fin (201) , and wherein each dividing wall (208) is attached to said first wall portion (206a) at a first respective level (L1) along the longitudinal direction (220) , extends towards an opposite second wall portion (206b) and is attached to the second wall portion (206b) at a respective second level (L2) along the longitudinal direction (220) , wherein the second respective level (L2) is different than the first respective level (L1) .
The heatsink fin (201) according to claim 1, wherein a line of direction extending from the first respective level (L1) to the second respective level (L2) of each respective dividing wall (208) has an angle (α) of about 20-70° in relation said longitudinal direction (220) .
The heatsink fin (301) according to any of the preceding claims, wherein each dividing wall (208) comprises at least a first part (308a) and second part (308b) , wherein

- the first part is attached to the first wall portion (206a) at the first respective level (L1) , and has an first angle (β) within the range of about 20-90° in relation to the longitudinal direction (220) of the heatsink fin (301) , and

- the second part (308b) is attached to the second wall portion (206b) at the second respective level (L2) , and has an second angle (γ) within the range of about 20-70° in relation to the longitudinal direction (220) of the heatsink fin (301) .
The heatsink fin (301) according to claim 3, wherein each dividing wall (208) further comprises a third dividing wall part (308c) , attached between the first part (308a) and the second part (308b) , and having an angle within the range of 0-70° in relation to the longitudinal direction (220) of the heatsink fin (301) .
The heatsink fin (201, 301) according to any preceding, wherein the envelope defines a cuboid comprising three pairs of opposite walls.
A heatsink (200) comprising a base portion (250) having a first side (252a) and an opposite second side (252b) , wherein the first side (252a) of the base portion (250) is configured to be in contact with a heat source (230) , and the second side (252b) of the base portion (250) is mounted with at least one heatsink fin (201, 301) according to any one of claims 1-5, wherein each sub-cavity (210, 310) is configured to be partly filled with refrigerant (240) .
The heatsink (200) according to claim 6, for each individual dividing wall (208, 308) , said first respective level (L1) is arranged to be located at a lower level compared to the second respective level (L2) , such that the refrigerant (240) is gathered in a lower part of each sub-cavity (210, 310) .
The heatsink (200) according to any of claim 6-7, wherein the heatsink fin (201, 301) is arranged so that said longitudinal direction (220) of the heatsink fin (201, 301) is parallel with a vertical plane, such that the refrigerant 240 is gathered in a lower part of each sub-cavity (210, 310) .
The heatsink (200) according to any of claim 6-8, wherein said first side (252a) of the heatsink (200) , which is in contact with the heat source (230) , extends in the vertical plane.
The heatsink (200) according to any of claim 6-9 wherein the heatsink (200) further comprises at least two heatsink fins, which are mounted parallel to each other and evenly distributed around the second side (252a) of the base portion (250) .
The heatsink (200) according to any of claim 6-10, wherein each sub-cavity (210, 310) is configured to be filled with refrigerant (240) up to a minimum level so that said refrigerant (240) covers the first wall portion (206a) which is in contact with the heat source (230) .
The heatsink (200) according to any of claim 6-11, wherein the heat source (230) is a radio transceiver.
A manufacturing method (400) of a heatsink fin (201, 301) according to claim 1-5, wherein each heatsink fin (201, 301) further comprises:

- a filling port (402) , and

- interconnection channels (404) between the sub-cavities, and

wherein the assembly process of each heatsink fin (201, 301) comprises the following steps:

filling (S002) the sub-cavities (210) with refrigerant (240) via the filling port (402) , the refrigerant (240) is evenly distributed throughout the sub-cavities (210) via the interconnection channels (404)

closing (S004) the filling port (402) ,

turning (S006) the heatsink fin (201, 301) along the horizontal central axis (406) , such that the refrigerant (240) will flow to the opposite side of each sub-cavities (210) ,

closing (S008) each interconnection channel (404) between the sub-cavies (210) .