Patent Description:
In many areas, for example within the field of telecommunications, components may require thermal cooling. This may for example be the case for components in a network access node for a wireless communication system, such as for example a base station. Thermal cooling involves a transfer of heat from the module or component which is to be cooled, e.g. to the ambient or to another module or component, such as an electrical active cooling device or a passive heat sink. A passive heat sink does not require electric power to transfer heat. In general, a heat sink may be seen as a passive heat exchanger configured to transfer heat from a heat-producing component to another medium, such as air or any other fluid medium, for example a liquid A heat sink can, for example, release the received heat partly or entirely to the ambient via cooling fins of a fin structure. Between the module or component to be cooled and an active cooling device or a heat sink, there may be structures and thermally insulating air gaps which impair the heat transfer to the active cooling device or heat sink.

Further, <CIT> refers to a receptacle assembly including a cage having an interior cavity that includes a port.

Further, <CIT>refers to a cage for thermal management and for housing an electronic module.

Further, <CIT> refers to a cage assembly provided for receiving a pluggable module.

The document <CIT>shows a heat transfer between two devices using a heat pipe.

The document <CIT>shows a heat transfer between two devices using a heat pipe, wherein the heat transfer apparatus is pressed to the two devices by springs.

This problem is solved by the subject matter of the independent claims. Further implementation forms are provided in the dependent claims.

The above and further objectives are solved by the subject matter of the independent claims. Further advantageous embodiments of the invention can be found in the dependent claims.

According to a first aspect of the invention, the above mentioned and other objectives are achieved with a device for transferring heat between a first module and a second module, the device comprising:.

The heat-transferring apparatus forms a helical shape. An advantage with this implementation form is that the heat-transferring apparatus is able to distribute deflection and bending stress/moment such that the stress in the heat-transferring apparatus can be minimized. The heat-transferring apparatus can thereby handle larger deflections and meet higher mechanical tolerance requirements.

Moreover, the heat-transferring apparatus is part of the biasing apparatus, and the helical heat-transferring apparatus is configured to urge the second unit away from the first unit, thereby urging the second unit against the second module placed in the holder. The biasing apparatus ensures a suitable contact pressure for good thermal transfer between the second module and the second unit. The biasing apparatus may comprise an elastic element or a resilient element (e.g. a spring) and may therefore be referred to herein also as a spring element or resilient element. An advantage with this implementation form is that the helical heat-transferring apparatus can provide or contribute to the force required to urge the second unit against the second module placed in the holder. Thereby, the design of the biasing apparatus can be simplified.

An advantage of the device according to the first aspect is that the heat-transferring apparatus can improve the thermal coupling between the first unit and the second unit such that an efficient heat transfer between the first module and
the second module can be provided. When the second module is a heat-generating module, the improved thermal coupling between the first unit and second unit provides an efficient heat transfer from the second module to the first module and hence an efficient cooling of the second module. The biasing apparatus ensures a suitable contact pressure for good thermal transfer between the second module and the second unit. Consequently, the heat transfer between the second module and the first module is improved and an improved heat dissipation is provided.

In an implementation form of a device according to the first aspect, the heat-transferring apparatus is a liquid-vapor phase-change heat-transferring apparatus. An advantage with this implementation form is that well-known principles of transferring heat based on evaporation and condensation can be used. Thereby, a reliable heat-transferring apparatus can be provided, and the manufacturing costs can be reduced.

In an implementation form of a device according to the first aspect, the heat-transferring apparatus is an elongated tubular heat-transferring apparatus. An advantage with this implementation form is an efficient design of the heat-transferring apparatus which improves the heat transfer and reduces the manufacturing costs.

In an implementation form of a device according to the first aspect, the heat-transferring apparatus forms a closed tube.

In an implementation form of a device according to the first aspect, the heat-transferring apparatus has an outer shell, wherein the heat-transferring apparatus at a hot interface is configured to turn a liquid inside the shell into a vapor inside the shell by allowing the liquid to absorb heat from the outer shell, whereupon the vapor travels along the heat-transferring apparatus to a cold interface, wherein the heat-transferring apparatus at the cold interface is configured to condense the vapor back into a liquid, and wherein the heat-transferring apparatus is configured to return the liquid to the hot interface by way of any one of capillary action and gravity. An advantage with this implementation form is that well-known principles of transferring heat based on evaporation and condensation can be used. Thereby, a reliable heat-transferring apparatus can be provided, and the manufacturing costs can be reduced.

In an implementation form of a device according to the first aspect, the heat-transferring apparatus comprises a heat pipe. An advantage with this implementation form is that a well-known product can be used. Thereby, a reliable heat-transferring apparatus can be provided, and the manufacturing costs can be reduced.

In an implementation form of a device according to the first aspect, the biasing apparatus comprises one or more compression springs. An advantage with this implementation form is that the biasing apparatus can be implemented using standard components which are reliable and inexpensive.

In an implementation form of a device according to the first aspect, the compression spring is located inside the helical shape of the heat-transferring apparatus. An advantage with this implementation form is that a compact and robust design of the biasing apparatus can be provided.

In an implementation form of a device according to the first aspect, the first unit is configured to be fixed in relation to the first module. "The first unit is configured to be fixed in relation to the first module" in the context of this embodiment means that the first unit is stationary in relation to the first module, i.e. the first unit does not move relative to the first module. An advantage with this implementation form is that a good thermal coupling between the first unit and the first module can be provide.

In an implementation form of a device according to the first aspect, wherein the holder comprises a compartment configured to receive and hold the second module. The compartment may further be configured to receive and hold the second module detachably.

In an implementation form of a device according to the first aspect, the device comprises a housing, which houses the compartment, and a printed circuit board, to which the housing is attached, wherein the compartment has a first opening for receiving the second module connectable to the printed circuit board, wherein the compartment has a second opening, and wherein the second unit comprises a protrusion, the protrusion being configured to engage the second opening and abut against the second module placed in the compartment. The embodiments of the device according to the invention are especially advantageous for such an implementation. Conventionally, an interface comprising a metal housing is often used for connecting a signal cable to a printed circuit board via a second module, for example a transceiver module, held by a compartment in the housing. By the second opening and embodiments of the device according to the present invention, an improved heat transfer is provided between the second module and the second unit for reasons mentioned above.

In an implementation form of a device according to the first aspect, the holder is configured to receive and hold a second module which is any module from the group comprising: a small form-factor pluggable, SFP, module and a quad small form-factor pluggable, QSFP, module.

An advantage with this implementation form is that a flexible mechanical connection for the second module is provided involving the known concepts SFP and QSFP.

In order to cool a module, for example an electrical component, an electrical active cooling device or a passive heat sink may be used. The use of an electrical active cooling device to cool the module has the disadvantage that the electrical active cooling device consumes power to lower the temperature. This leads to high costs and to the generation of heat load in other parts or components close to the module.

Another disadvantage with conventional cooling is that air gaps may be present between the module to be cooled and the electrical active cooling device or the passive heat sink. Air gaps introduces high thermal resistance and makes it more difficult to cool the module. In order to avoid air gaps a thermally conductive filling material, which provide and facilitate the heat transfer, may be placed between the module to be cooled and the active cooling device or the passive heat sink. Conventional thermal interface materials are resilient to a certain extent to be able to expand and fill the air gaps but may lose their resilient character completely or to some degree after some time in a compressed state. Thus, the thermal interface material may for example not properly expand and fill the air gaps when the module is removed and replaced or reintroduced after inspection. This leads to thermally insulating air gaps which reduces the heat transfer between the module and the electrical active cooling device or the passive heat sink. There may hence be a temperature increase in the module, which results in an increased risk of overheating and a shortened lifetime of the module.

According to embodiments of the invention, a device for transferring or conducting heat between a first module and a second module is disclosed. The device improves the heat transfer between the first module and the second module and can address manufacturing variances with regard to the first module and the second module. The device further maintains its flexibility over time.

<FIG> schematically illustrates two devices <NUM> according to embodiments of the invention, a first device 102a and a second device 102b. Each of the first device 102a and the second device 102b is configured to transfer or conduct heat between a first module <NUM> and a respective second module <NUM>. Only one second module <NUM> is shown in <FIG>. The configuration and functionality of the two devices 102a, 102b will now be described with reference to the first device 102a.

In the embodiment shown in <FIG>, the second module <NUM> is a heat-generating module and the first device 102a hence transfers heat from the second module <NUM> to the first module <NUM>. The first device 102a comprises a holder <NUM> for holding the second module <NUM>. The first device 102a further comprises a first unit <NUM> configured to be thermally coupled to the first module <NUM>. By thermal coupling is meant that there is a heat transfer between the first unit <NUM> and the first module <NUM>, or in other words, that there is a heat-conducting communication between the first unit <NUM> and the first module <NUM>. The first unit <NUM> may be thermally coupled to the first module <NUM>, for example through direct physical abutment or via additional thermally conductive material.

In embodiments of the first device 102a, the first unit <NUM> is configured to be fixed, or in other words stationary, in relation to the first module <NUM> such that the first unit <NUM> does not move relative to the first module <NUM>. The first unit <NUM> may further be configured to be connected to the first module <NUM>. The first unit <NUM> may be connected/attached to the first module <NUM> by using for example a mechanical fastening means or an adhesive. Alternatively, the first unit <NUM> may be integral with the first module <NUM>, i.e. formed as a unit with the first module <NUM>. When the first unit <NUM> is attached to the first module <NUM>, a thermal interface material, TIM, may be arranged between the first unit <NUM> and the first module <NUM> to further reduce thermal resistance between them.

The first device 102a further comprises a second unit <NUM> movable in relation to the first unit <NUM> and the holder <NUM>. The first device 102a also includes a biasing apparatus <NUM>, <NUM> for urging (or forcing or biasing) the second unit <NUM> away from the first unit <NUM>, thereby urging the second unit <NUM> against the second module <NUM> placed in the holder <NUM>, as illustrated in <FIG>. Thus, the biasing apparatus <NUM>, <NUM> urges the second unit <NUM> into contact with the second module <NUM> such that a thermal coupling is provided between the second unit <NUM> and the second module <NUM>. The second unit <NUM> may be thermally coupled to the second module <NUM> through direct physical abutment or via additional thermally conductive material.

Furthermore, the first device 102a comprises a liquid- and vapor-based heat-transferring apparatus <NUM> attached to the first unit <NUM> and the second unit <NUM>. The heat-transferring apparatus <NUM> may also be denoted a heat transfer apparatus <NUM>. The heat-transferring apparatus <NUM>, or heat transfer apparatus <NUM>, thermally couples the second unit <NUM> to the first unit <NUM>. Thus, the heat-transferring apparatus <NUM> provides a heat transfer between the second unit <NUM> and the first unit <NUM>.

With reference to <FIG>, the heat-transferring apparatus <NUM> may have a first end <NUM> which is configured to be attached to the first unit <NUM>. Further, the heat-transferring apparatus <NUM> may have a second end <NUM> which is configured to be attached to the second unit <NUM>. The heat-transferring apparatus <NUM> may be attached to the first unit <NUM> and the second unit <NUM>, respectively, using for example soldering, brazing, pressing, a mechanical fastening means, or an adhesive.

As illustrated in <FIG>, the second device 102b comprises parts corresponding to the above described parts of the first device 102a. The first and second devices 102a, 102b may be independent of each other or may be partly connected or integrated with each other. In other words, the first and second devices 102a, 102b may operate independently from each other or may co-operate.

<FIG> schematically illustrates parts of the first and second devices 102a, 102b according to an embodiment of the invention where the first and second devices 102a, 102b are partly connected. With reference to <FIG>, the first unit 110a of the first device 102a and the first unit 110b of the second device 102b are connected or attached to each other. The first units 110a, 110b may be fixed in relation to each other such that they do not move relative to each other. Thus, the first units 110a, 110b may be kept at the same level in relation to one another and for example be connected or attached to the same first module <NUM>. However, the second unit 112a of the first device 102a and the second unit 112b of the second device 102b are not directly connected or attached to one another. Instead they 112a, 112b are arranged separate from each other. In this way, the second units 112a, 112b may move independently between their respective first unit 110a; 110b and the holder <NUM>. The fact that the second units 112a, 112b can move independently from each other ensures that a good contact pressure and hence a good thermal transfer can be achieved between the second unit 112a; 112b and its respective second module <NUM> held in the holder <NUM>.

In some embodiments, the heat-transferring apparatus <NUM> may be a liquid-vapor phase-change heat-transferring apparatus <NUM>, such as for example a two-phase cooling system based on evaporation and condensation. The heat-transferring apparatus <NUM> may for example comprises a heat pipe. A heat pipe per se is known and provides cooling based on liquid-vapor phase-change.

<FIG> schematically illustrates the heat-transferring apparatus <NUM> according to an embodiment of the invention, where the heat-transferring apparatus <NUM> is based on liquid-vapor phase-change. With reference to <FIG>, the heat-transferring apparatus <NUM> has an outer shell <NUM>, a hot interface <NUM> and a cold interface <NUM>. The heat-transferring apparatus <NUM> is configured to, at the hot interface <NUM>, turn a liquid inside the shell <NUM> into a vapor inside the shell <NUM> by allowing the liquid to absorb heat from the outer shell <NUM>, whereupon the vapor travels along the heat-transferring apparatus <NUM> to the cold interface <NUM>. At the cold interface <NUM>, the heat-transferring apparatus <NUM> is configured to condense the vapor back into a liquid, and to return the liquid to the hot interface <NUM> by way of any one of capillary action and gravity. Heat is hence removed from the hot interface <NUM> and transferred to the cold interface <NUM> of the heat-transferring apparatus <NUM>. In this way, the heat-transferring apparatus <NUM> transfers heat from one end of the heat-transferring apparatus <NUM> to an opposite end of the heat-transferring apparatus <NUM>. With reference to <FIG>, the heat-transferring apparatus <NUM> may hence transfer heat from the second end <NUM> attached to the second unit <NUM> to the first end <NUM> attached to the first unit <NUM>. The hot interface <NUM> may be a surface for vaporising the liquid into a vapour. The cold interface <NUM> may be a surface for condensing the vapour into a liquid.

The heat-transferring apparatus <NUM> may be an elongated tubular heat-transferring apparatus <NUM>. The tubular shape of the heat-transferring apparatus <NUM> may be closed, as illustrated for example in <FIG>. Hence, the heat-transferring apparatus <NUM> may in some embodiments form a closed tube <NUM>. In a non-limiting example, the tubular shape or the closed tube may have an essentially circular cross-section with a diameter of about <NUM>. However, the tubular shape or the closed tube may in some embodiments instead have an oval or flat shape with other dimensions.

According to embodiments, the heat-transferring apparatus <NUM> forms at least a part of a helical shape or forms a helical shape. The helical shape may correspond to a curve in three-dimensional space and may also be referred to as a coil shape. The fact that the heat-transferring apparatus <NUM> forms at least a part of a helical shape may mean that the heat-transferring apparatus <NUM> forms less than one complete helix turn, e.g. only half a helix turn. The helical shape of the heat-transferring apparatus <NUM> may have different dimensions such that the heat-transferring apparatus <NUM> may be adapted to be used in different applications. For example, the pitch, i.e. the height of one complete helix turn, of the helical shape may be adapted based on the distance between the first module <NUM> and the holder <NUM> and/or the mechanical properties of the heat-transferring apparatus <NUM>.

In the embodiment shown in <FIG>, the heat-transferring apparatus <NUM> is a helical coil spring forming one complete helix turn. The pitch of the helical coil spring is selected such that the distance between the first module <NUM> and the holder <NUM> can be bridged. One end <NUM> of the helical coil spring is attached to the first unit <NUM> and the second end <NUM> is attached to the second unit <NUM>.

According to embodiments of the invention, the heat-transferring apparatus <NUM> may form other shapes than a helical shape. The heat-transferring apparatus <NUM> may for example be at least partly straight, form a U-shape or form other geometrical shapes. <FIG> schematically illustrates a device <NUM> comprising a heat-transferring apparatus <NUM> with an essentially straight shape. The position of the first unit <NUM> relative to the second unit <NUM> may be adapted to the shape of the heat-transferring apparatus <NUM> such that the heat-transferring apparatus <NUM> can be attached to both the first unit <NUM> and the second unit <NUM>. As illustrated in <FIG>, when the heat-transferring apparatus <NUM> has an essentially straight shape, the first unit <NUM> may be arranged at an distance from the second unit <NUM>, where the distance is selected such that the heat-transferring apparatus <NUM> is able to handle bending moments at its two attached ends, where the bending moments arise from mechanical movements of for example the second unit <NUM>.

As previously described, the biasing apparatus <NUM>, <NUM> is configured to urge the second unit <NUM> away from the first unit <NUM>, thereby urging the second unit <NUM> against the second module <NUM> placed in the holder <NUM>. With reference to <FIG>, the biasing apparatus <NUM>, <NUM> hence urges the second unit <NUM> towards contact with the second module <NUM> such that a good thermal coupling is achieved between the second unit <NUM> and the second module <NUM>. Furthermore, the biasing apparatus <NUM>, <NUM> may be arranged such that the entire area of a first surface of the second unit <NUM> is urged against the second module <NUM>. In this way an even pressure over the entire contact surface between the second unit <NUM> and the second module <NUM> can be achieved.

The biasing apparatus <NUM>, <NUM> may comprise one or more compression springs <NUM>. The one or more compression springs <NUM> may comprises any compression spring from the group comprising: a helical spring, a volute spring, a conical spring, a hollow tubing spring and a spring washer. The location of the one or more compression springs <NUM> may be selected such that a stable movement of the second unit <NUM> between the first unit <NUM> and the holder <NUM> can be achieved and further such that an even pressure over the entire contact surface between the second unit <NUM> and the second module <NUM> can be achieved.

With reference to <FIG>, the biasing apparatus <NUM> may comprise two compression springs <NUM>. In <FIG>, four compression springs <NUM> are shown since two devices 102a, 102b are shown. The compression springs <NUM> may be located inside the helical shape of the heat-transferring apparatus <NUM>. In this way the compression springs may be at least partly covered by the heat-transferring apparatus <NUM>. However, the compression springs <NUM> may in embodiments instead be located outside the helical shape of the heat transferring apparatus <NUM>.

When the heat-transferring apparatus <NUM> is resilient for example by having a helical shape and/or comprising at least partly a resilient material, the heat-transferring apparatus <NUM>, <NUM> may be part of the biasing apparatus <NUM>, <NUM>. In such embodiments, the helical heat-transferring apparatus <NUM>, <NUM> is hence configured to urge the second unit <NUM> away from the first unit <NUM>, thereby urging the second unit <NUM> against the second module <NUM> placed in the holder <NUM>. The resilience of the heat-transferring apparatus <NUM> may be such that the heat-transferring apparatus <NUM> can urge the second unit <NUM> against the second module <NUM> without the need of any compression spring <NUM>. Thus, the biasing apparatus <NUM> may in some embodiments only comprise the heat-transferring apparatus <NUM>.

According to embodiments of the invention, the holder <NUM> may comprise a compartment <NUM> configured to receive and hold the second module <NUM>. In the embodiment shown in <FIG>, the holder <NUM> comprises two compartments <NUM>, where each compartment <NUM> can receive and hold one second module <NUM>. However, the holder <NUM> may have fewer or more compartments <NUM>. In <FIG>, the compartment <NUM> to the right is illustrated without a second module <NUM> while the compartment <NUM> to the left is illustrated with a second module <NUM> received and held therein. The compartment <NUM> may be configured to detachably secure the second module <NUM> such that the second module <NUM> can be replaced or removed and re-inserted into the compartment <NUM>.

In some embodiments, the compartment <NUM> is housed in a housing <NUM> as schematically illustrated in <FIG>. Thus, the device <NUM> may in some embodiments comprise a housing <NUM>. The housing <NUM> houses the compartment <NUM> and is attachable to a printed circuit board (not shown in the figures). The housing <NUM> may also be referred to as a case or casing and may for example be a metal casing. The housing <NUM> illustrated in <FIG> comprises two compartments <NUM>, each compartment <NUM> having a first opening <NUM> for receiving the second module <NUM> connectable to the printed circuit board. Each compartment <NUM> further has a second opening <NUM> which exposes at least a part of the second module <NUM> when held in the compartment <NUM>.

With reference to <FIG>, the second opening <NUM> of the compartment <NUM> may face the second unit <NUM> and the second unit <NUM> may comprise a protrusion/projection/boss <NUM> configured to engage the second opening <NUM> and abut against the second module <NUM> placed in the compartment <NUM>. The second unit <NUM> is thus brought into physical and thermal contact with the second module <NUM> held in the compartment <NUM>. The physical and thermal contact between the second unit <NUM> and the second module <NUM> may in some embodiments be provided via additional thermally conductive material. The protrusion <NUM> of the second unit <NUM> together with the biasing apparatus <NUM>, <NUM> urging the second unit <NUM> away from the first unit <NUM> ensures a good thermal connection between the second unit <NUM> and the second module <NUM> held in the compartment <NUM> of the housing <NUM>. To allow the second module <NUM> to easily be inserted and removed from the compartment <NUM>, the protrusion <NUM> of the second unit <NUM> may have tampered edges, as indicated in <FIG>. This provides sliding surfaces between the protrusion <NUM> and the second module <NUM> and hence prevents the second module <NUM> to be caught by an edge of the protrusion <NUM> during insertion and removal of the second module <NUM>.

The second unit <NUM> may cover the second opening <NUM>. When the second unit <NUM> covers the second opening <NUM>, shielding against electromagnetic interference can be provided. This reduces the risk of electromagnetic interference, EMI, leakage to and/or from the second module <NUM> through the second opening <NUM>. Thereby, the risk that the second module <NUM> causes interference to an antenna or other electrical components nearby is reduced, as well as the risk of interference in the second module <NUM> caused by signals from an antenna or from other electrical components nearby. Thus, an improved heat transfer can be provided between the second module <NUM> and the first module <NUM> without an increased risk of electromagnetic interference leakage.

According to embodiments of the invention the holder <NUM> may be configured to hold a second module <NUM> which is a transceiver module to which a signal cable is connectable. The second module <NUM> may for example be an optical transceiver module to which an optical signal cable, for example an optical fibre cable, is connected. However, the transceiver module may also be configured to be connectable to an electrical signal cable. The device <NUM> according to the embodiments of the present invention may be especially advantageous for applications where the second module <NUM> is an optical transceiver module, since when converting optical signals from the optical signal cable to electrical signals for transmission to the printed circuit board, the optical transceiver module generates a substantial amount of heat, which should be dissipated or transferred away from the optical transceiver module, to protect the optical transceiver module from heat, since the optical transceiver module is sensitive to high temperatures. The reliability and lifetime of a transceiver module is related to the module temperature. Typical allowed maximum temperatures for the optical transceiver module is <NUM> or <NUM>. The temperature of the optical transceiver module can be reduced by <NUM>-<NUM>, but also by more, for example by <NUM>-<NUM>, if a thermally insulating air gap or air pocket is avoided by the use of the device <NUM>.

The holder <NUM> may further be configured to receive and hold a second module <NUM> which is any module from the group comprising: a small form-factor pluggable (SFP) module and a quad small form-factor pluggable (QSFP) module. The holder <NUM> may hence be an SFP or QSFP housing configured to receive the SFP module or the QSFP module, respectively. The signal cable, which may be an optical fibre cable, may be connectable to the SFP or QSFP module. SFP and QSFP per se are known to the person skilled in the art and are thus not further described in this disclosure.

The embodiments of the present invention also include an arrangement <NUM> for cooling a second module <NUM>. <FIG> shows the arrangement <NUM> according to an embodiment of the invention. The arrangement <NUM> comprises a first device 102a according to any one of the embodiments disclosed above, and a first module <NUM> which comprises a heat sink <NUM>. With reference to <FIG>, the first module <NUM> may be in the form of a heat sink <NUM> having cooling fins for heat dissipation. The arrangement <NUM> may further comprise the second module <NUM> held in the first device 102a. The arrangement <NUM> improves the heat transfer from the second module <NUM> to the first module <NUM> by means of embodiments of the first device 102a. Consequently, the arrangement <NUM> can provide an improved heat dissipation.

With reference to <FIG>, the arrangement <NUM> may further comprise a second device 102b according to any one of the embodiments disclosed above. Thus, the arrangement <NUM> may in embodiments comprise two devices 102a, 102b. Each device 102a, 102b may be structured according to any one of the embodiments disclosed above. Furthermore, each device 102a, 102b may provide cooling of a respective second module <NUM>. In <FIG>, only one second module <NUM> is illustrated. The first device 102a provides heat transfer from and hence cooling of this second module <NUM>. The second device 102b is configured to provide cooling of an additional second module <NUM> when placed in the empty compartment <NUM> to the right in the holder <NUM> in <FIG>.

The embodiments of the present invention also include a network access node for a wireless communication system. The network access node comprises any one of the device <NUM> and the arrangement <NUM> according to any one of the embodiments disclosed above. The network access node may comprise a base station, for example a base radio station. The network access node may include one or more antennas. The base station may have a housing which houses the antenna. Alternatively, the antenna is mounted outside the housing of the base station, for example with a distance to the housing of the base station. The antenna may in embodiments be connectable to the printed circuit board comprised in the device <NUM> via a suitable cable. By means of embodiments of the device <NUM> and/or embodiments of the arrangement <NUM> an improved heat dissipation can be provided in the network access node.

The network access node herein may also be denoted as a radio network access node, an access network access node, an access point, or a base station, e.g. a Radio Base Station (RBS), which in some networks may be referred to as transmitter, "gNB", "gNodeB", "eNB", "eNodeB", "NodeB" or "B node", depending on the technology and terminology used. The radio network access nodes may be of different classes such as e.g. macro eNodeB, home eNodeB or pico base station, based on transmission power and thereby also cell size. The radio network access node can be a Station (STA), which is any device that contains an IEEE <NUM>-conformant Media Access Control (MAC) and Physical Layer (PHY) interface to the Wireless Medium (WM). The radio network access node may also be a base station corresponding to the fifth generation (<NUM>) wireless systems.

Claim 1:
A device (<NUM>; 102a, 102b) for transferring heat between a first module (<NUM>) and a second module (<NUM>), the device (<NUM>; 102a, 102b) comprising:
• a holder (<NUM>) for holding the second module (<NUM>),
• a first unit (<NUM>) configured and arranged to be thermally coupled to the first module (<NUM>),
• a second unit (<NUM>) configured and arranged to be movable in relation to the first unit (<NUM>) and the holder (<NUM>),
• a biasing apparatus (<NUM>, <NUM>) configured and arranged for urging the second unit (<NUM>) away from the first unit (<NUM>), thereby urging the second unit (<NUM>) against the second module (<NUM>) placed in the holder (<NUM>), and
• a liquid- and vapor-based heat-transferring apparatus (<NUM>) attached to the first unit (<NUM>) and the second unit (<NUM>), wherein the liquid- and vapor-based heat-transferring apparatus (<NUM>) is configured and arranged to thermally couple the second unit (<NUM>) to the first unit (<NUM>),
wherein the liquid- and vapor-based heat-transferring apparatus (<NUM>) forms a helical shape,
wherein the liquid- and vapor-based heat-transferring apparatus (<NUM>) is part of the biasing apparatus (<NUM>), and wherein the helical heat-transferring apparatus (<NUM>, <NUM>) is configured to urge the second unit (<NUM>) away from the first unit (<NUM>), thereby urging the second unit (<NUM>) against the second module (<NUM>) placed in the holder (<NUM>).