WO2013054327A2

WO2013054327A2 - Cooling system and method

Info

Publication number: WO2013054327A2
Application number: PCT/IL2012/050388
Authority: WO
Inventors: David MOYAL; Haviv ELBAZ
Original assignee: Elta Systems Ltd.
Priority date: 2011-10-11
Filing date: 2012-09-24
Publication date: 2013-04-18
Also published as: IL215700A; WO2013054327A3; IL215700A0

Abstract

A heat sink device configured for conduction cooling of at least one heat generating component that is mounted to a first face of a substrate is disclosed. The heat sink device includes a heat transfer body configured for being mounted with respect to the substrate and at least one heat transfer unit that includes a heat transfer element configured for providing a heat transfer path between the heat generating component and the heat transfer body. The heat transfer unit includes a first thermal contact surface configured for providing thermal contact between the heat transfer unit and the heat generating component in operation of the heat sink device. The heat transfer element includes a second thermal contact surface different the first thermal contact surface and in thermal communication with the first thermal contact surface. The heat transfer element is movably mounted with respect to the heat transfer body for selective displacement in at least a first direction with respect to the heat transfer body while concurrently providing thermal contact between the second thermal contact surface and the heat transfer body. Also disclosed are a corresponding conduction cooled module and a corresponding method for assembling a conduction cooled module.

Description

COOLING SYSTEM AND METHOD

TECHNOLOGICAL FIELD

The presently disclosed subject matter relates to systems and methods for cooling heat-generating components, in particular electronic heat-generating components that are mounted on substrates including for example PCBs, in particular to the conduction cooling thereof.

BACKGROUND

There are many conventional electronic devices such as, for example, computer systems, in which electronic components are mounted on printed circuit boards (also referred to as PCBs or as circuit cards), which are assembled into PCB modules. The PCB modules are commonly inserted into a chassis of the electronic device. The PCB modules may also include additional circuit cards, such as mezzanine cards, which are electrically connected to a main PCB via a connector.

Proper cooling of electronic components in general, and those mounted on PCBs as above in particular, is essential, otherwise excessive heat generated by the electronic components can cause malfunctions and failure thereof.

Conventionally, PCBs and, consequently, PCB modules, are generally convection cooled or conduction cooled.

Convection cooled card modules (commonly known as AFT modules) are conventionally mounted within the chassis of an electronic device in such a way as to allow the free flow of cooling air (or other fluid medium) over electronic components to dissipate excess heat generated via convection. The flow of air is usually provided by a fan.

Conduction cooled PCB modules are conventionally used where there exist severe requirements for protection of their PCBs from harsh environment, such as for example sand, dust, humidity etc., and/or in closed electronic enclosures where air ventilation is impossible. In such conduction cooled PCB modules, heat generated by electronic components of the PCB is absorbed by an internal heat transmitting layer thereof, often made of copper, and thereby forwarded to a heat dissipation device (heat sink), often provided by the chassis itself in which the module is mounted. Since a conduction-cooled PCB does not require a heat exchange air flow to be provided over 5 its electronic components, it can be hermetically sealed within its module, and is thus particularly suitable for use in a sealed electronic device.

In conventional conduction cooled modules, the amount of heat that may be removed from electronic components via conduction is rather low (typically about 15- 20 Watt), and various attempts have been made to improve conduction cooling in 10 conduction cooled PCBs.

One conventional approach is to provide thermal contact between a heat sink and the electronic components via suitable Thermal Interface Material (TIM) in the form of soft and thermally conductive viscoelastic pads, which physically deform in situ to compensate for dimensional errors or deviations during manufacturing and/or 15 assembly that may result in a wide range of variations of the respective spacing between the electronic component and the heat sink. Other conventional approaches include the use of other TIM's in the form of thermal grease or thermal paste to provide thermal contact between a heat sink and the electronic components.

By way of general background, US 6,392,891, US 7,031,167 and US 20 2005/0152118 disclose examples of conduction cooled PCB modules.

GENERAL DESCRIPTION

According to a first aspect of the presently disclosed subject matter there is provided a heat sink device (also referred to interchangeably herein as a cooling system)

25 configured for conduction cooling of at least one heat generating component (such as for example an electronic component) that is mounted to a first face (or a first surface) of a substrate, such as for example a printed circuit board (PCB), the heat sink device comprising a heat transfer body configured for being mounted to the substrate (or PCB) and at least one heat transfer unit comprising a heat transfer member configured for

30 providing a heat transfer path between the heat generating component and said heat transfer body, said at least one heat transfer unit comprising a first thermal contact surface configured for providing thermal contact between said heat transfer unit and the at least one heat generating component in operation of said heat sink device, said at least one heat transfer member comprising a second thermal contact surface different from said first thermal contact surface and in thermal communication with said first thermal contact surface, said heat transfer member being movably mounted with respect to said heat transfer body for selective displacement in at least a first direction with respect to said heat transfer body while concurrently providing thermal contact between said second thermal contact surface and said heat transfer body.

In at least some examples, said heat transfer element is displaceable along at least said first direction responsive to said heat transfer body being mounted to the substrate (or PCB) and said first thermal contact surface being at least one of in abutting contact and in thermal contact with the at least one heat generating component, wherein to provide said displacement.

Additionally or alternatively said heat transfer member is movably mounted with respect to said heat transfer body for selective reversible displacement in at least said first direction with respect to said heat transfer body while concurrently providing said thermal contact between said second thermal contact surface and said heat transfer body.

Additionally or alternatively the heat sink device comprises a biasing arrangement to maintain said heat transfer unit in abutting thermal contact with said heat transfer body at least when partially displaced along said displacement.

Additionally or alternatively said heat transfer member is made from a first thermally conductive material.

Additionally or alternatively said heat transfer unit is rigid and is displaced along said displacement as a rigid body.

Additionally or alternatively heat transfer body comprises a body thermal contact surface, and wherein said second thermal contact surface is in thermal contact with said heat transfer body via said body thermal contact surface.

Additionally or alternatively said second thermal contact surface is inclined at a wedge angle with respect to said first thermal contact surface. For example, said wedge angle is greater than a limiting value aiim given by: μ = tan a_Um

where μ is the coefficient of friction between said second thermal contact surface and said thermal transfer body. Additionally or alternatively said wedge angle (in the absence of lubricating material) is less than 70°, or less than 60°, or less than 55°, or less than 50°, or less than 45°, or less than 40°, or less than 35°, or less than 30°, or less than 25°, or less than 20°, or less than 15°. Additionally or alternatively said wedge angle (in the absence of lubricating material) is more than 60°, or more than 55°, or more than 50°, or more than 45°, or more than 40°, or more than 35°, or more than 30°, or more than 25°, or more than 20°, or more than 15°, or more than 10°. Additionally or alternatively said wedge angle (in the absence of lubricating material) is in the range between about 15° and about 75°, or between about 15° and about 55°, or between about 15° and about 45°, or between about 25° and about 55°, or between about 35° and about 60°. For example said wedge angle (in the absence of lubricating material) is any one of 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, or 70°.

Alternatively, a suitable lubricating material is provided between said second thermal contact surface and said heat transfer body. For example, said lubricating material reduces the effective coefficient of friction between said second thermal contact surface and said thermal transfer body; for example said wedge angle is less than said limiting value aii_m. For example, said lubricating material is a thermal grease or a thermal paste. Additionally or alternatively said wedge angle (using a suitable lubricating material) is less than 50°, or less than 45°, or less than 40°, or less than 35°, or less than 30°, or less than 25°, or less than 20°, or less than 15° or less than 10°, or less than 5°. Additionally or alternatively said wedge angle (using a suitable lubricating material) is more than 45°, or more than 40°, or more than 35°, or more than 30°, or more than 25°, or more than 20°, or more than 15°, or more than 10°, or more than 5°, or more than 0°. Additionally or alternatively said wedge angle (using a suitable lubricating material) is in the range between about 0° and about 50°, or between about 1° and about 50°, or between about 0.5° and about 45°, or between about 0.1° and about 15°, or between about 1° and about 15°. For example said wedge angle (using a suitable lubricating material) is any one of 0.1°, 1°, 2°, 3°, 4°, 5°, 6°, 7°, 8°, 9°, 10°, 11°, 12°, 13°, 14°, 15°, 16°, 17°, 18°, 19°, or 20°. Additionally or alternatively said heat transfer body comprises at least a portion thereof made from a second thermally conductive material, said portion being in said thermal contact with said second thermal contact surface and defining a conduction thermal path away from said at least one heat transfer unit. For example, said heat transfer body is formed as a contiguous article made from said second thermally conductive material. Alternatively, said heat transfer body is formed as a composite body comprising a frame made of a first material and enclosing said portion made from said second thermally conductive material, said first material being the same as or different from said second thermally conductive material.

Additionally or alternatively when said heat transfer body is mounted to the substrate (or PCB) said heat sink is spaced from said at least one heat generating component along a depth direction. For example, said first direction is generally parallel to said depth direction. Additionally or alternatively said heat transfer element is movably mounted with respect to said heat transfer body for selective displacement further in at least a second direction with respect to said heat transfer body, different from said first direction, while concurrently providing said thermal contact between said second thermal contact surface and said heat transfer body. For example, said first direction is generally parallel to said depth direction and said second direction is generally orthogonal to said depth direction. Additionally or alternatively said thermal contact is defined along a plane inclined to said first direction and to said second direction. Additionally or alternatively said heat transfer element is in the form of a wedge movably accommodated in a recess formed in said heat transfer body for displacement with respect thereto along said first direction and said second direction, and wherein said first thermal contact surface is generally parallel to a heat transfer surface of the said at least one heat generating component, and wherein said second thermal transfer surface is inclined with respect to said first thermal contact surface.

In at least some examples, said first direction is generally orthogonal to said depth direction. For example, said heat transfer unit further comprises an auxiliary heat transfer element movably engaged with respect to said heat transfer body for selective displacement in at least a second direction with respect to said heat transfer body, different from said first direction, while concurrently providing said thermal contact between said second thermal contact surface and said heat transfer body, and wherein said auxiliary heat transfer unit comprises said first transfer surface. For example, said second direction is generally parallel to said depth direction. Additionally or alternatively said thermal contact between said second thermal contact surface and said heat transfer body is defined along a first plane generally orthogonal to said depth direction. Additionally or alternatively said heat transfer body comprises a third heat transfer surface and wherein said auxiliary heat transfer body comprises a fourth heat transfer surface, and wherein said auxiliary heat transfer element is movably mounted with respect to said heat transfer unit to concurrently provide thermal contact between said third thermal contact surface and said fourth thermal transfer surface. For example, said thermal contact between said third thermal contact surface and said fourth thermal transfer surface is defined along a second plane inclined to said first direction and to said second direction. Additionally or alternatively said heat transfer element is in the form of at least one first wedge member movably accommodated in a recess formed in said heat transfer body to move with respect thereto along said first direction and wherein said auxiliary heat transfer element is in the form of a second wedge member movably engaged to said at least one first wedge member to concurrently move with respect thereto along said second direction, and wherein said first thermal contact surface is generally parallel to a heat transfer surface of the said at least one heat generating component, and wherein said second thermal transfer surface is inclined with respect to said first thermal contact surface. For example said second thermal transfer surface is orthogonally inclined with respect to said first thermal contact surface. Additionally or alternatively said auxiliary heat transfer element is affixed to the at least one heat generating component, and wherein said auxiliary heat transfer element is reversibly movably engaged with respect to said first wedge member. Additionally or alternatively said heat transfer unit comprises a plurality of first wedge members, each said first wedge member being movably accommodated in a respective recess formed in said heat transfer body to move with respect thereto along a respective said first direction and wherein said auxiliary heat transfer element is in the form of a second wedge member movably engaged to each said first wedge member to concurrently move with respect thereto along said second direction, and wherein said first thermal contact surface is generally parallel to a heat transfer surface of the said at least one heat generating component, and wherein each respective said second thermal transfer surface of each said first wedge member is inclined with respect to said first thermal contact surface. For example, each said second thermal transfer surface is orthogonally inclined with respect to said first thermal contact surface. Additionally or alternatively said auxiliary heat transfer unit is affixed to the at least one heat generating component, and wherein said auxiliary heat transfer unit is reversibly movably engaged with respect to each respective said second wedge members. For example:

- said at least one heat generating component is chosen form a group including: any electronic component including a CPU; any other electronic device that during operation thereof generates undesired thermal energy; and/or

- wherein said substrate is a PCB.

According to a second aspect of the presently disclosed subject matter there is provided a conduction cooled module, for example a conduction cooled PCB module, comprising:

a first said heat sink device, as defined above for the first aspect of the presently disclosed subject matter;

a substrate (for example a PCB) comprising at least one said heat generating component;

said heat transfer body being mounted to said substrate (or PCB), said first thermal contact surface being in thermal contact with said at least one heat generating component, and said second thermal contact surface being in thermal contact with said heat transfer body.

For example, the first said heat sink device is hermetically mounted to said circuit board to define a first internal space comprising said at least one said heat generating component mounted to said first face.

Additionally or alternatively said first thermal contact surface is in contact with said at least one heat generating component at a first spacing from said first face, and wherein said selective displacement of said heat transfer element allows said first spacing to be within a predetermined first spacing range while concurrently providing said thermal contact between said second thermal contact surface and said heat transfer body. For example, said predetermined first spacing range includes a variation in said first spacings provided by a plurality of alternative said heat generating component each of which can be alternately mounted to said first face and in thermal contact with said heat sink device via said heat transfer unit. For example, said variation in said first spacings at least partially originates from undefined or variable manufacturing tolerances of the respective said heat generating components. Additionally or alternatively said variation in said first spacings at least partially originates from dimensional deviations from nominal of the respective mounting position of the respective said heat generating components on the said first face during mounting operation thereon. Additionally or alternatively said variation in said first spacings include a range of between about 0 mm and about 1mm; for example said variation in said first spacings can be 0.1mm, or 0.2mm, or 0.3mm or 0.4mm,or 0.5mm, or 0.6mm, or 0.7mm, or 0.8mm, or 0.9mm, or 1.0mm.

Additionally or alternatively the conduction cooled module further comprises a heat extraction arrangement in thermal contact with said conduction cooled module and configured for transferring heat away from said conduction cooled module via said first said heat sink device.

Additionally or alternatively said substrate (or PCB) comprises at least one heat generating component that is mounted to a second face of the substrate (or PCB), said second face and said first face facing each facing mutually opposite directions, and further comprising a second said heat sink device hermetically mounted to said circuit board to define a second internal space comprising said at least one said heat generating component mounted to said second first face.

Additionally or alternatively said at least one heat generating component is chosen form a group including: any electronic component including a CPU; any other electronic device that during operation thereof generates undesired thermal energy.

According to a second aspect of the presently disclosed subject matter there is provided a method for assembling a conduction cooled module, for example a conduction cooled PCB module, comprising:

(a) providing a first heat sink device, said heat sink device being as defined above for the first aspect of the presently disclosed subject matter;

(b) providing a substrate (for example a PCB) comprising at least one said heat generating component; (c) mounting said heat transfer body to said substrate (or PCB) ensuring said first thermal contact surface is in thermal contact with said at least one heat generating component, and said second thermal contact surface is in thermal contact with said heat transfer body.

For example:

- wherein said substrate is a PCB.

A feature of at least some examples of the presently disclosed subject matter is that much higher levels of heat can be removed from electronic components via conduction as compared with conventional MIT's (for example using only thermal grease, or using only thermal paste, or using viscoelastic pads with or without thermal grease/thermal paste), for example higher than about 20 Watt.

Herein, "substrate" is taken to include any material, object, structure, base element, and so on, on which it is desired to mount a heat generating component (e.g. a heat generating electronic component), the respective heat sink device being mounted to the substrate and configured for dissipating thermal energy (away from the heat generating component) via thermal contact with the heat generating component (in particular thermal conductive contact) and conduction through the heat sink device. The substrate can have any suitable shape, for example including a sheet-like shape or non- sheet like shape, and having a face or surface on which the heat generating component can be mounted, and this face or surface can be generally flat or can be generally contoured, for example including generally concave-shaped parts, and/or generally convex-shaped parts, or can have any other suitable shape, whether contiguous or noncontiguous. BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the presently disclosed subject matter and to see how it may be carried out in practice, examples will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

Fig. 1 is an isometric exploded view of a conduction cooled module according to a first example of the present presently disclosed subject matter;

Fig. 2 is another isometric exploded view of the example of Fig. 1 ;

Fig. 3 is an exploded isometric view of a heat transfer unit of the example of

Fig. 1 ;

Fig. 4 is an isometric view of the heat transfer unit of the example of Fig. 3;

Fig. 5 is a side view of the heat transfer unit of the example of Fig. 3 accommodated in the conduction cooled module of the example of Fig. 1 at one spacing between the substrate and the heat sink;

Fig. 6 is an isometric and partial view of the example of Fig. 5;

Fig. 7 is a side view of the heat transfer unit of the example of Fig. 3 accommodated in the conduction cooled module of the example of Fig. 1 at a different spacing between the substrate and the heat sink;

Fig. 8 is an isometric and partial view of the example of Fig. 7;

Fig. 9 is a side partial view of a conduction cooled module according to a second example of the present presently disclosed subject matter; Fig. 9(a) is a partial cross sectional view of the example of Fig. 9 taken along section A-A; Fig. 9(b) is a partial cross sectional view of the example of Fig. 9 taken along section B-B;

Fig. 10 is a side partial view of a conduction cooled module according to a variation of the example of Fig 9. DETAILED DESCRIPTION

Referring to Figs. 1 and 2, a conduction cooled module according to a first example of the presently disclosed subject matter, generally designated with the reference numeral 100, generally comprises a substrate in the form of a printed circuit board or PCB (also referred to interchangeably herein as a printed circuit card, substrate, or PCB) 50, and a heat sink device 60.

PCB 50 comprises a front face or surface 52 and a rear face or surface 54, and further comprises a plurality of heat generating components in the form of electronic components 80, each mounted in the conventional manner or any other suitable manner onto front face 52. While the figures show four such electronic components 80 mounted to PCB 50 it is readily evident that PCB 50 can comprise more than four, or less than four, i.e., at least one such electronic component 80 or other heat generating component mounted onto front surface 52.

The heat sink device 60 (also referred to interchangeably herein as a cooling system) comprises a heat transfer body 61, in the form of a thermally conductive frame member, and at least one heat transfer unit 15.

In this example at least one of the PCB 50 and the heat sink device 60 is configured for being mounted to the other one of the heat sink device 60 and the PCB 50. In particular, the heat sink device 60 (in particular the heat transfer body 61) is configured for being sealably mounted hermetically to the PCB 50 (or alternatively vice versa) via mating surfaces around the respective peripheries thereof, with a rear face 62 of heat transfer body 61 generally facing electronic components 80 and front face 52.

For example, such electronic components 80 or other heat generating components can comprise CPU's and/or any other electronic devices that during operation thereof generate thermal energy and wherein it is desired, according to an aspect of the present presently disclosed subject matter, to dissipate such energy via conduction through the heat sink device 60. Typically, each such electronic component 80 or other heat generating component comprises an outer-facing, substantially planar thermal contact surface 82 (also referred to herein as a heat exchange surface) configured for enabling heat generated by the electronic component 80 to be extracted therefrom at least via conduction. For example, the thermal contact surface 82 can be formed as an expanded die or can be the thermal contact surface of a heat spreader suitably mounted to or formed on the electronic component 80.

The heat transfer body 61 comprises a pair of extractors 64, pivotally mounted on an upper edge 68 of heat transfer body 61, for facilitating insertion/extraction of the 5 conduction cooled module 100 into the chassis (not shown).

For convenience orthogonal Cartesian axis system C is defined having axes Z, X generally co-planar with surfaces 52, 54, and a third axis Y in the depth direction substantially orthogonal to said surfaces 52, 54.

In this example heat sink device 60 comprises a plurality of heat transfer units 10 15 mounted thereto, each in a respective position in general registry with a respective electronic component 80 of the conduction cooled module 100.

In alternative variations of the first example in which the PCB 50 can further comprise at least one electronic component 80 or another heat generating component mounted onto rear face 54, and another heat sink device including a corresponding heat 15 transfer body and heat transfer units can be provided for the conduction cooling thereof, similar to heat sink device 60 including heat transfer body 61 and heat transfer unit 15, mutatis mutandis.

Referring also to Figs. 3 to 8, each heat transfer unit 15 of the conduction cooled module 100 is configured for providing a heat transfer path (in particular a thermally

20 conductive heat transfer path) between the respective electronic component 80 and the heat transfer body 61. In this example, each heat transfer unit 15 comprises a wedge- shaped, prismatic, heat transfer element 10 (also interchangeably referred to herein as a heat-conductive transfer element or as a transfer element), having a boss 12 projecting from rear face 13, a substantially planar thermal contact surface 17 inclined at a wedge

25 angle a to rear face 13, a top face 16, and generally wedge-shaped side faces 21.

Boss 12 comprises a substantially planar thermal contact surface 14 (also interchangeably referred to herein as a heat exchange surface), spaced by dimension H2 from rear face 13 (see Fig. 5). Thermal contact surface 14 is configured for forming thermal contact with thermal contact surface 82 of the respective electronic component 30 80 (directly, or indirectly via a suitable thermally conductive material) in operation of the conduction cooled module 100. The thermal contact surface 17 is also inclined at wedge angle a to thermal contact surface 14.

In the first example, and referring in particular to Fig. 4, thermal contact surface 14 is flat and rectangular, having a length dimension L2 along the Z direction and a 5 width X2 along the X direction, and thermal contact surface 82 is also flat and rectangular. However, it is to be noted that in alternative variations of the example the thermal contact surface 14 and thermal contact surface 82 can have any shape.

The heat transfer unit 15 further comprises a plate-like mounting base 40, having a window 49 therein through which boss 12 projects. Referring in particular to Fig.4,

10 window 49 has a dimension L4 along the Z direction substantially larger than length dimension L2 of boss 12 to allow relative movement between heat transfer element 10 and the mounting base 40 along direction Z while boss 12 projects through window 49. Window 49 has a dimension X4 along the X direction slightly larger than width X2 of boss 12 to provide a clearance therebetween, and thus allow such relative movement

15 between heat transfer element 10 and the mounting base 40 along direction Z without causing fouling between the window 49 and the projecting boss 12.

The heat transfer element 10 is held loosely with respect to mounting base 40 via alignment arrangement 25, which in this example comprises three pins 11 projecting from top face 16 and passing through respective elongated holes 19 provided in bracket

20 42, which is provided on base 40 in general parallel relationship with rear face 13.

Elongated holes 19 allow the respective pins 11 to move therethrough along axis Z for the range of relative movement along this axis between the heat transfer element 10 and mounting base 40 (i.e., as permitted by the difference between dimensions L4 and L2, while restricting movement along the X axis. The holes 19 are elongated along the Y

25 direction to allow relative movement between the pins 11 and holes 19 also in the Y direction also during the aforesaid range of relative movement along this axis between the heat transfer element 10 and mounting base 40.

Referring in particular to Figs. 3 and 5, biasing arrangement 71 is provided, in the form of compression springs 70 generally concentric with pins 11, each spring 70 30 having one end in abutment with top face 16, and the other end in abutment with bushing 30, located between the top face 16 and bracket 42. Bushing 30 comprises holes 35 through which the pins 11 project. Referring in particular to Figs. 1, 4 and 5, a chamber 20 is provided in the heat transfer body 61 for accommodating each respective heat transfer unit 15, and the mounting base 40 is received in a peripheral recess 65 (Fig. 1) to achieve a generally flush or coplanar relationship between the rear surface 47 of mounting base 40 (Fig. 4) and the rear surface 62 of the heat transfer body 61. The heat transfer unit 15 is affixed to the heat transfer body 61 via bolts 76, though any other suitable fixing arrangement can be used instead.

Referring in particular to Figs. 5 and 7, each chamber 20 comprises a top part 22 configured for accommodating therein the alignment arrangement 25 of the respective heat transfer unit 15, and a heat transfer part 24, contiguous with top part 22 and configured for maintaining continuous thermal contact between heat transfer body 61 and heat transfer element 10 in operation of the module 100. Heat transfer part 24 comprises a sloping surface 28 that is configured to provide sliding, abutting and thermal contact with thermal contact surface 17 along a respective thermal contact plane P.

Biasing arrangement 71, which is a compression-based mechanism in this example, is configured for biasing the heat transfer element 10 in direction 91 to maintain thermal contact surface 17 in abutment with sloping surface 28 at a position PI along the Z direction (Fig. 5) corresponding to the maximum displacement of the heat transfer element 10 with respect to mounting base 40 along this direction. In position PI the thermal contact surface 14 projects maximally from window 49 by dimension Tl. Furthermore, the springs 70 are also configured for being less than fully compressed at a position P2 (Fig. 7) along the Z direction corresponding to the minimum displacement of the heat transfer element 10 with respect to mounting base 40 in this direction, and thus is still capable of still biasing the heat transfer element 10 in direction 91 to maintain thermal contact surface 17 in abutment with sloping surface 28. In position P2, the thermal contact surface 14 projects minimally from window 49 by dimension T2.

Referring to Figs. 5 and 6, and starting with heat transfer element 10 in position PI, in response to a displacement of thermal contact surface 14 in direction 95 (generally parallel to the Y axis) towards position P2, the heat transfer element 10 moves within chamber 20 as thermal contact surface 17 slides over sloping surface 28 in direction 96 along plane P, which concurrently provides a movement of the heat transfer element 10 in direction 93 parallel to the Z axis, thereby compressing springs 70. The pins 11 are concurrently displaced in direction 93 (nominally orthogonal to direction 95) within elongated holes 19, and the stored energy in the spring 70 continuously biases the thermal contact surface 17 to abut sloping surface 28.

Thus, as thermal contact surface 14 is displaced and translated in direction 95 from the maximum projection Tl to the minimum projection T2 with respect to window 49, the heat transfer element 10 concurrently moves in direction 93 (parallel to the Z axis) from position PI to position P2 (an aggregate displacement of ΔΡ = PI - P2), and in direction 95 parallel to the Y axis (by an aggregate displacement of ΔΤ =T1 - T2). The relationship between ΔΡ and ΔΤ is determined by the magnitude of wedge angle a.

The compression-based biasing arrangement 71 is configured for providing reversible operation, and thus as thermal contact surface 14 is translated in a direction opposed to direction 95 from the minimum projection T2 to the maximum projection Tl, the stored energy in springs 70 still provides a corresponding biasing force abutting thermal contact surface 17 against sloping surface 28.

Heat transfer element 10 is made from a suitable thermally conductive material, for example copper or any other suitable metal, which can be the same as or different from the suitable thermally conductive material from which the heat transfer body 61 is made.

In assembling the module 100, heat sink device 60 is mounted hermetically to the PCB 50, and each electronic component 80 on the top face 52 thereof is in general registry with a respective heat transfer unit 15 that is mounted to the heat transfer body 61, wherein each respective thermal contact surface 82 is in general and at least partial overlapping relationship with the respective thermal contact surface 14.

Thus, the heat transfer element 10 is movably mounted to the heat sink device 60 via the respective heat transfer unit 15 and configured for selective displacement in at least a first direction with respect to said heat transfer body 61 while concurrently providing thermal contact between thermal contact surface 17 and said heat transfer body 61. Each heat transfer unit 15 is configured for use with an electronic component 80 which, when mounted to the PCB 50 in module 100, has the respective spacing S between the respective thermal contact surface 82 and the heat transfer body 61, for example the rear face 62 thereof, within a predetermined range SI (maximum) to S2 (minimum) (Figs. 5 and 7).

Spacing S thus corresponds to

S = D - Q

wherein D is the spacing between front surface 52 and rear surface 62, and Q is the spacing between the respective thermal contact surface 82 and the front surface 52, and thus maximum spacing SI corresponds to a minimum spacing Ql of Q, and minimum spacing S2 corresponds to a maximum spacing Q2 of Q.

Thus, such a heat transfer unit 15 can be used with a range of different types of electronic component 80, so long as they meet the aforesaid criteria where S1>S>S2 (i.e., the S-range), corresponding to a Q-range of Q1<Q<Q2). Additionally or alternatively, the heat transfer unit 15 can be used with a particular type of electronic component 80, wherein the actual spacing S corresponding thereto can in practice vary between SI and S2 due to, for example, undefined or variable manufacturing tolerances of component 80 and/or of the PCB 50 and/or dimensional deviations from nominal or design values during mounting operation on the PCB 50.

For this purpose, the respective boss 12 is sized having dimension H2 along the

Y-direction (see Fig. 5) such that at position PI the thermal contact surface 14 is spaced from the heat transfer body 61, in particular the rear face 62 thereof, by a spacing Tl not less than spacing SI, so that an electronic component 80 having its respective spacing S at the upper end SI of the S-range (and thus minimum spacing Ql) will have its respective thermal contact surface 82 in contact with thermal contact surface 14. Furthermore, dimension H2 is also chosen such that at position P2 the thermal contact surface 14 still remains spaced from the heat transfer body 61, in particular the rear face 62 thereof, by a spacing T2 not less than S2, so that another electronic component 80 having its respective spacing S at the lower end of the range S2 will have its respective thermal contact surface 82 in contact with thermal contact surface 14. Thus, the S-range SI to S2 does not exceed the T-range Tl to T2 at either end thereof. According to this aspect of the presently disclosed subject matter, as the heat sink device 60 is mounted to the PCB 50, for each opposed pair of electronic component 80 and heat transfer unit 15, thermal contact surface 82 comes into thermal contact with thermal contact surface 14 and furthermore the thermal contact surface 82 pushes against the heat transfer element 10 displacing the same in direction 95 by an actual displacement corresponding to spacing S for that particular electronic component 80. Concurrently, the heat transfer element 10 moves in direction 93 by a corresponding displacement via sliding motion between thermal contact surface 17 and sloping surface 28 along plane P in direction 96, and thus sliding thermal contact between thermal contact surface 17 and sloping surface 28 is maintained via biasing springs 70 during displacement of the heat transfer unit 15. A thermal conduction path is thus automatically provided between thermal contact surface 82 and the heat transfer body 61 (primarily via conductive thermal contact between thermal contact surface 82 and thermal contact surface 14), the thermally conductive material in heat transfer element 10, and via thermally conductive contact between thermal contact surface 17 and sloping surface 28, regardless of the actual magnitude of dimension S (so long as it is between the range limits SI and S2), thereby enabling heat generated by the respective electronic component 80 to be dissipated by conduction to the heat transfer body 61 and thereafter by other suitable means, which are per se known, for example.

In this example, heat transfer element 10 is made from a substantially rigid material, which does not substantially deform when subject to a closing force that tends to displace it between the limits Tl and T2, and thus a very high level of thermal contact is maintained between thermal contact surface 17 and sloping surface 28. The heat transfer element 10 is a rigid body, and is made from any suitable heat conductive material, for example, from any suitable metal, for example copper, and the aforesaid closing force is within a reasonable range expected when assembling the module 100, far below the level required for deforming such a material. In other words, by rigid material is meant a material in which any deformation thereof in response to the application of the closing force is not significant with respect to the range of displacement between Tl and T2 and thus does not contribute significantly to the displacement of the heat transfer element 10 with respect to the heat sink device 60 or the heat sink body 61 in particular. Thus, the heat transfer unit 15, in particular the heat transfer element 10 is displaced as a rigid body during assembly operation of module 100.

It is to be noted that corresponding to the range SI to S2, there is always an overlapping contact area between thermal contact surface 82 and thermal contact surface 14, along the X and Z directions, and such overlapping contact area can be maximized for this range SI to S2. In at least one alternative variation of this example all of the surface 82 is in overlapping thermal contact with surface 14, and for example a heat spreader can be mounted to the component 80 so that the upper surface of the heat spreader constitutes the surface 82, thereby ensuring that there is always 100% overlapping contact between the surface 82 (of the heat spreader) and surface 14 for range SI to S2.

In an alternative variation of the first example, a suitable lubricating material, such as for example thermal grease KERATHERM KP-68 (provided by KERAFOL GmbH, Germany) can be provided between one or more of the following pairs of surfaces, said lubricating material being further configured to maintain thermal contact between the respective pair of surfaces:

between thermal contact surface 82 and thermal contact surface 14; between thermal contact surface 17 and sloping surface 28.

In particular, such lubricating material can be provided between thermal contact surface 17 and sloping surface 28 in applications where it is desired or necessary to have a relatively shallow wedge angle a, in particular where the wedge angle a is less than a limiting value <¾„ given by:

μ = tan a_Um (1)

where μ is the coefficient of friction between thermal contact surface 17 and sloping surface 28. In such circumstances, the aforesaid lubricating material effectively reduces the coefficient of friction and thus enables relative movement between thermal contact surface 17 and sloping surface 28 wherein in the absence of the lubricating material no relative sliding movement would be possible between thermal contact surface 17 and sloping surface 28 in response to any force in direction 95 attempting to displace the heat transfer element 10 in this direction at the aforesaid wedge angle a being less than a limiting value aum - In the absence of said lubricating material, the wedge angle a is at least not less than, e.g. is greater than the aforesaid limiting value It is to be noted that equation (1) does not take into account other forces that can be present and acting on the heat transfer element 10.

By way of non-limiting example, in the absence of a lubricating material said wedge angle a can be less than 60°, or less than about 50°, or less than about 40°, or less than about 30°, or less than 20°, or less than 15°. For example, in the absence of the lubricating material said wedge angle a can be, in the range of between about 15° to about 55°.

By way of non-limiting example, using a suitable lubricating material (such as for example thermal grease KERATHERM KP-68 (provided by KERAFOL GmbH, Germany)) between thermal contact surface 17 and sloping surface 28, said wedge angle a can be less than 45°, or less than about 40°, or less than about 35°, or less than about 20°, or less than 15°, or less than 10°, or less than about 5°. For example, using the lubricating material said wedge angle a can be, in the range of between about just above 0° to about 5°, or in the range of just above 0° to about 10° or in the range of just above 0° to about 15°.

In at least some examples, reducing the wedge angle a can be desired for minimizing the width E (see Fig. 5) of the heat transfer body 61 or heat sink device 60.

In any of the above variations or yet other alternative variations of the first example, the alignment arrangement and/or biasing arrangement can be different from alignment arrangement 25 and/or springs 70, respectively, mutatis mutandis. For example the biasing arrangement can be, instead, uncoupled from the alignment arrangement and each one located at a different position with respect to the conduction cooled module. Additionally or alternatively the biasing arrangement can comprise springs having their longitudinal axis not parallel to axis Z, but rather inclined thereto at any suitable angle. Additionally or alternatively, a different biasing arrangement can be provided for biasing thermal contact surface 17 into abutting contact with sloping surface 28 for example via a tension-based mechanism or a sealed heat resistant and/or thermally conductive bellows enclosing a compressible gas under a suitable pressure can be provided, rather than a compression-based mechanism. Alternatively, the biasing arrangement can be configured for providing non-reversible biasing contact between thermal contact surface 17 and sloping surface 28, and thus only provides a biasing force as thermal contact surface 14 is translated in a direction 95, but having done so does not provide the biasing force if the thermal contact surface 14 is now translated in a direction opposed to direction 95. For example, such a biasing arrangement can comprise an energy absorbing mechanism comprising a material capable of nonreversible progressive deformation, and thus deforms by an amount corresponding to the displacement of the heat transfer element 10 within chamber 20 along direction 95. For example, the energy absorbing mechanism can be in the form of at least one solid energy absorbing element capable of progressive deformation, for example and is at least partially made of metal foam such as for example aluminum foam. Additionally or alternatively the alignment mechanism can comprise a kinematic pair arrangement in which the heat transfer element 10 and the heat transfer body 61 form a kinematic pair, wherein relative movement therebetween is constrained to a direction 96 parallel to plane P, and can comprise for example a key and groove (aligned in direction 96), one comprised in the heat transfer element 10 and the other in heat transfer body 61.

Alternatively, in any of the above or yet other alternative variations of the first example, the biasing arrangement and/or alignment arrangement can be omitted, and the heat transfer element 10 can be fixed in place in chamber 20 in any suitable manner, in a position providing thermal contact between thermal contact surface 17 and sloping surface 28 on the one hand, and thermal contact between thermal contact surface 82 and thermal contact surface 14 on the other hand, corresponding to the particular dimension S of the electronic component 80, when this dimension S is known.

In the first example or any of the above or yet other alternative variations thereof, the heat transfer element 10 can thus move in two degrees of freedom in translation, i.e., along the Z and Y axes.

In any of the above or yet other alternative variations of the first example the heat transfer unit 15 can also be configured for allowing and compensating for deviations from a particular norm relating to the orientation of the thermal contact surface 82 with respect to the front face 52 of the PCB 50. According to such a norm, the thermal contact surface 82 is nominally parallel to the front face 52, and thus such deviations refer to inclinations of the thermal contact surface 82 with respect to the front face 52. In one such variation of the first example, the boss 12 can be formed in two parts joined together at a curved or hemispheric interface (and in mutual thermal contact via the interface, optionally via a suitable thermal conductive lubricant), wherein to allow relative rotational movement between the two parts in one, two or three rotational degrees of freedom. Such an arrangement allows for the thermal contact surface 14, in such circumstances, to come into full thermal contact with thermal contact surface 82, via the aforesaid rotational movement of the two parts of boss 12, while at the same time maintaining full abutting and thermal contact (directly or indirectly via a suitable lubricating material as disclosed herein) between thermal contact surface 17 and sloping surface 28.

In this example, the heat transfer body 61 is made from a suitable thermally conductive material, for example a metal such as copper. The heat transfer body 61 can be formed as a contiguous article made from the thermally conductive material.

In alternative variations of this example, the heat transfer body 61 comprises at least a portion thereof made from a thermally conductive material, and this portion is in thermal contact with thermal contact surface 17 and defines a conduction thermal path away from the heat transfer unit 15. The heat transfer body 61 can be formed as a composite body comprising a frame member made from any suitable (thermally conductive or non- thermally conductive) mechanically supportive material, the frame member being configured for enclosing this portion, which is made from a thermally conductive material. The frame material can be the same as the thermally conductive material, or can comprise a different thermally conductive material, or can comprise a material that is not thermally conductive, for example a heat insulator.

In alternative variations of this example, the module 100 can further comprise one or more mezzanine cards situated between the PCB 50 and the heat sink device 60, and any heat generating components that can be mounted to the mezzanine cards can be cooled in any suitable manner, for example via thermally conductive viscoelastic pads, thermal grease or thermal paste placed between each such heat generating component and the heat sink device 60.

It is to be noted that in the first example and in at least some alternative variations thereof, the PCB 50 can be replaced with any other suitable substrate (for example a ceramic substrate) on which it is desired to mount the heat generating component (e.g. electronic component 80), the heat sink device 60 being mounted to the substrate and configured for dissipating thermal energy (generated by the heat generating component) via conduction through the heat sink device 60.

Referring to Figs. 9, 9(a) and 9(b), a second example of the conduction cooled module, generally designated with the reference numeral 200, generally comprises a PCB 50, including at least one electronic component 80, as disclosed herein for the first example and/or any other said variation of the first example, mutatis mutandis. The conduction cooled module 200 further comprises a heat sink device 260, comprising the elements and features of heat sink device 60 of the first example and/or any other said variation of the first example, with some differences mutatis mutandis, as will become clearer herein. In the second example, heat sink device 260 comprises a heat transfer body 261 and a plurality of heat transfer units 215 mounted thereto (though of course can comprise at least one heat transfer unit 215 mounted thereto), each in a respective position in general registry with a respective electronic component 80 of the conduction cooled module 200.

Each heat transfer unit 215 of the conduction cooled module 200 comprises a first wedge-shaped, prismatic, heat transfer element 210 (also referred to herein as a heat-conductive transfer element, or as a transfer element), similar in some ways to heat transfer element 10, mutatis mutandis, but having a top face 213, a thermal contact front face 216, a substantially planar thermal contact surface 217 inclined at a wedge angle a to front face 216, and generally wedge-shaped side faces. Heat transfer unit 215 is slidingly accommodated in chamber 220 provided in heat transfer body 261, and constrains movement of heat transfer unit 215 in chamber 220 along the Z axis only. To provide such constraint, any suitable alignment arrangement can be used, for example a key and groove arrangement illustrated in Fig. 9(a) forming a kinematic pair. Thermal contact front face 216 is in thermal contact with thermal contact surface 228 of chamber 220.

Planar thermal contact surface 217 defines a thermal transfer plane B.

Heat transfer unit 215 further comprises an auxiliary heat transfer unit in the form of a second wedge-shaped, prismatic, heat transfer element 290 (also referred to herein as a heat-conductive transfer element, or as a transfer element, also similar in some ways to heat transfer element 10, mutatis mutandis, but having a bottom face 298, having a boss 292 projecting from rear face 299, a substantially planar thermal contact surface 297 inclined at a wedge angle a to rear face 299, and generally wedge-shaped side faces.

Boss 292 comprises a substantially planar thermal contact surface 294 (also referred to herein as a heat exchange surface), spaced by dimension H5 from rear face 299, and is configured for forming thermal contact with thermal contact surface 82 of the respective electronic component 80 in operation of the conduction cooled module 200. The dimension H5 is such as to enable the planar thermal contact surface 294 to project from the rear surface 262 of heat transfer body 261 by a dimension T, wherein T1>T>T2, in a similar manner to that of the planar thermal contact surface 14 with respect to rear surface 62 of the first example, mutatis mutandis.

At least in operation of the conduction cooled module 200, the planar thermal contact surface 297 is in thermal contact with planar thermal contact surface 217 along thermal transfer plane B, and moreover, the planar thermal contact surface 297 is configured for sliding movement with respect to planar thermal contact surface 217 along thermal transfer plane B while maintaining thermal contact therebetween. In the second example, second heat transfer element 290 is slidingly mounted to first heat transfer element 210, in a manner to constrain relative movement along plane B, in particular in direction 296 aligned with the Y-Z plane. To provide such constraint, any suitable alignment arrangement can be used, for example a key and groove arrangement illustrated in Fig. 9(b) forming a kinematic pair.

A suitable biasing arrangement 225 is provided to bias the heat transfer unit 215 in direction 291 along the Z axis.

When the heat sink device 260 is hermetically sealed onto PCB 50 comprising an electronic device 80 mounted to PCB 50 and having its thermal contact surface 82 at an unknown in-situ spacing S (spacing S being, however, within the limits SI and S2 as described for the first example, mutatis mutandis), thermal contact surface 82 abuts against thermal contact surface 294 and pushes the transfer element 290 in direction 295 parallel to the Y axis until the thermal contact surface 294 projects from rear surface 262 by a spacing T that is equal to spacing S. Concurrently with this movement, there is relative movement between the second heat transfer element 290 and the first heat transfer element 210, in particular sliding movement between thermal contact surface 297 and thermal contact surface 217 along plane B, which in turn concurrently causes heat transfer element 210 to be displaced along the Z axis in direction 293, and the biasing arrangement 225 helps to maintain the following abutting pairs of thermal contact surfaces in mutual thermal contact:

thermal contact surface 297 in thermal contact with thermal contact surface 217;

thermal contact surface 294 in thermal contact with thermal contact surface 82;

thermal contact surface 228 in thermal contact with thermal contact surface 216.

Thus, a thermal conduction path is thus automatically provided between thermal contact surface 82 and the heat sink device 260 (primarily via thermal contact between thermal contact surface 82 and thermal contact surface 294), the thermally conductive material in second heat transfer element 290, via thermal contact between thermal contact surface 297 and thermal contact surface 217, the thermally conductive material in first transfer element 210, and via thermal contact between thermal contact surface 216 and thermal contact surface 228. Such a conduction path is maintained regardless of the actual magnitude of spacing S (so long as it is between the limits SI and S2), thereby enabling heat generated by the respective electronic component 80 to be dissipated by conduction to the heat sink device 260 and thereafter by other suitable means, which are per se known, for example, in a similar manner to the first example, mutatis mutandis.

It is to be noted that, also in a similar manner to the first example, mutatis mutandis, the second example also provides thermal contact between the heat sink device 260 and the electronic device 80 having a spacing S within the range SI to S2, and furthermore, corresponding to the range SI to S2 there is always an overlapping contact area between thermal contact surface 82 and thermal contact surface 294, and in the second example the overlapping area is constant and fixed, since the heat transfer element 290 can be constrained to only move in the Y axis.

In a similar manner to that disclosed for the first example, mutatis mutandis, any suitable biasing arrangement and/or alignment arrangement can be used, or omitted, in at least some alternative variations of the second example. In a similar manner to that disclosed for the first example, mutatis mutandis, a suitable lubricating material, such as for example thermal grease, for example KERATHERM KP-68 (provided by KERAFOL GmbH, Germany) can be provided between one or more of the following pairs of surfaces, said lubricating material being further configured to maintain thermal contact between one or more of the following respective pairs of surfaces:

between thermal contact surface 297 and thermal contact surface 217;

between thermal contact surface 294 and thermal contact surface 82; between thermal contact surface 228 and thermal contact surface 216.

In an alternative variation of the second example, transfer body 290 can be attached to the electronic device 80 via surface 82, and can thus be considered part of the electronic device 80 and not of the heat transfer unit 215. In such an example the heat transfer element 290 is not necessarily slidingly mounted to heat transfer element 210, but rather abuts thereto in a manner to constrain relative movement along plane B, in particular in direction 296 aligned with the Y-Z plane. To provide such constraint, any suitable alignment arrangement can optionally be used that also allows for the heat transfer element 290 to detach from heat transfer element 210 in a direction normal to plane B, for example a key and groove arrangement illustrated in Fig. 9(a) forming a kinematic pair.

Referring to Fig. 10, in another variation of the second example, conduction cooled module 200 further comprises a heat sink device 260', similar to heat sink device 60, comprising the elements and features of heat sink device 60 of the first example and/or any other said variation of the first example, with some differences mutatis mutandis, as will become clearer herein. The respective heat transfer unit 215' of heat sink device 260' comprises a pair of heat transfer elements 210 (also designated as heat transfer element 210A and heat transfer element 210B), mounted in opposed relationship in respective chambers 220 (also designated as respective chamber 220A and respective chamber 220B) formed in heat transfer body 261', and comprising biasing arrangements 225A, 225B, and another heat transfer element 290' is provided on the electronic device 80 in thermal contact therewith. Heat transfer element 290' has a pair of sloping thermal contact surfaces 297', each in contact with a different one of the two heat transfer elements 210A, 210B via a respective thermal contact surface 217A, 217B. In this example, when the heat sink device 260' is hermetically sealed onto PCB 50, the electronic device 80 having its thermal contact surface 82 at an unknown in-situ spacing S (S being within the limits SI and S2 as described for the first and second examples, mutatis mutandis), thermal contact surfaces 297' each abuts against the respective thermal contact surface 217A, 217B, and as the heat transfer element 290' moves in direction 295 parallel to the Y axis together with the PCB 50 and electronic device 80, each of heat transfer elements 210A, 210B concurrently moves, providing sliding movement between the respective thermal contact surface 297' and thermal contact surface 217 along the respective plane B, which in turn concurrently causes each heat transfer element 210A, 210B to be displaced along the Z axis in a direction away from heat transfer element 290', and each biasing arrangement 225 A, 225B helps to maintain the abutting pairs of thermal contact surfaces in thermal contact, in a similar manner to the second example, mutatis mutandis. Optionally a suitable lubricating material, for example thermal grease, for example KERATHERM KP-68 (provided by KERAFOL GmbH, Germany), can be provided between one or more of the thermal surfaces that are in thermal contact, and the lubricating material is further configured to maintain such thermal contact between the respective pairs of surfaces.

In alternative variations of the second example in which the PCB 50 can further comprise at least one electronic component 80 mounted onto rear face 54 another heat sink device including a heat transfer body and heat transfer units can be provided for the conduction cooling thereof, similar to heat sink device 260, heat transfer body 261 and heat transfer unit 215, or similar to heat sink device 260' and heat transfer unit 215', or to heat sink device 60 and heat transfer unit 15, mutatis mutandis.

In the method claims that follow, alphanumeric characters and Roman numerals used to designate claim steps are provided for convenience only and do not imply any particular order of performing the steps.

Finally, it should be noted that the word "comprising" as used throughout the appended claims is to be interpreted to mean "including but not limited to".

Claims

1. A heat sink device configured for conduction cooling of at least one heat generating component that is mounted to a first face of a substrate, the heat sink device comprising:

a heat transfer body configured for being mounted with respect to the substrate and at least one heat transfer unit comprising a heat transfer element configured for providing a heat transfer path between the heat generating component and said heat transfer body,

said at least one heat transfer unit comprising a first thermal contact surface configured for providing thermal contact between said heat transfer unit and the at least one heat generating component in operation of said heat sink device,

said heat transfer element comprising a second thermal contact surface different from said first thermal contact surface and in thermal communication with said first thermal contact surface,

said heat transfer element being movably mounted with respect to said heat transfer body for selective displacement in at least a first direction with respect to said heat transfer body while concurrently providing thermal contact between said second thermal contact surface and said heat transfer body.

2. The heat sink device according to claim 1, wherein said heat transfer element is displaceable along at least said first direction responsive to said heat transfer body being mounted to the substrate and said first thermal contact surface being in abutting contact with the at least one heat generating component, wherein to provide said displacement.

3. The heat sink device according to claim 1 or claim 2, wherein said heat transfer element is movably mounted with respect to said heat transfer body for selective reversible displacement in at least said first direction with respect to said heat transfer body while concurrently providing said thermal contact between said second thermal contact surface and said heat transfer body.

4. The heat sink device according to any one of claims 1 to 3, comprising a biasing arrangement to maintain said heat transfer unit in abutting thermal contact with said heat transfer body at least when partially displaced along said displacement.

5. The heat sink device according to any one of claims 1 to 4, wherein said heat transfer element is made from a first thermally conductive material.

6. The heat sink device according to any one of claims 1 to 5, wherein said heat transfer element is rigid and is displaced along said displacement as a rigid body.

7. The heat sink device according to any one of claims 1 to 6, wherein heat transfer body comprises a body thermal contact surface, and wherein said second thermal contact surface is in thermal contact with said heat transfer body via said body thermal contact surface.

8. The heat sink device according to any one of claims 1 to 7, wherein said second thermal contact surface is inclined at a wedge angle with respect to said first thermal contact surface.

9. The heat sink device according to claim 8, wherein said wedge angle is greater than a limiting value <¾„ given by:

μ = tan a_Um

where μ is the coefficient of friction between said second thermal contact surface and said thermal transfer body.

10. The heat sink device according to claim 8 or claim 9, wherein said wedge angle is in the range between about 15 degrees and about 55 degrees.

11. The heat sink device according to claim 8 or claim 9, wherein said wedge angle is in the range between about 0 degrees and about 15 degrees

12. The heat sink device according to any one of claims 8 to 11 , wherein a suitable lubricating material is provided between said second thermal contact surface and said heat transfer body.

13. The heat sink device according to claim 12, wherein said lubricating material reduces the effective coefficient of friction between said second thermal contact surface and said thermal transfer body.

14. The heat sink device according to claim 13, wherein said wedge angle is less than said limiting value

15. The heat sink device according to any one of claims 12 to 14, wherein said lubricating material is a thermal grease or a thermal paste.

16. The heat sink device according to any one of claims 1 to 15, wherein said heat transfer body comprises at least a portion thereof made from a second thermally conductive material, said portion being in said thermal contact with said second thermal contact surface and defining a conduction thermal path away from said at least one heat

5 transfer unit.

17. The heat sink device according to claim 16, wherein said heat transfer body is formed as a contiguous article made from said second thermally conductive material.

18. The heat sink device according to claim 16, wherein said heat transfer body is formed as a composite body comprising a frame made of a first material and enclosing

10 said portion made from said second thermally conductive material, said first material being the same as or different from said second thermally conductive material.

19. The heat sink device according to any one of claims 1 to 18, wherein when said heat transfer body is mounted to the substrate said heat sink is spaced from said at least one heat generating component along a depth direction.

15 20. The heat sink device according to claim 19, wherein said first direction is generally parallel to said depth direction.

21. The heat sink device according to claim 19 or claim 20, said heat transfer element is movably mounted with respect to said heat transfer body for selective displacement further in at least a second direction with respect to said heat transfer

20 body, different from said first direction, while concurrently providing said thermal contact between said second thermal contact surface and said heat transfer body.

22. The heat sink device according to claim 21, wherein said first direction is generally parallel to said depth direction and said second direction is generally orthogonal to said depth direction.

25 23. The heat sink device according to any one of claims 21 to 22, wherein said thermal contact is defined along a plane inclined to said first direction and to said second direction.

24. The heat sink device according to any one of claims 21 to 23, wherein said heat transfer element is in the form of a wedge movably accommodated in a recess formed in 30 said heat transfer body for displacement with respect thereto along said first direction and said second direction, and wherein said first thermal contact surface is generally parallel to a heat transfer surface of the said at least one heat generating component, and wherein said second thermal transfer surface is inclined with respect to said first thermal contact surface.

25. The heat sink device according to claim 19, wherein said first direction is generally orthogonal to said depth direction.

26. The heat sink device according to claim 25, said heat transfer unit further comprising an auxiliary heat transfer element movably engaged with respect to said heat transfer body for selective displacement in at least a second direction with respect to said heat transfer body, different from said first direction, while concurrently providing said thermal contact between said second thermal contact surface and said heat transfer body, and wherein said auxiliary heat transfer unit comprises said first transfer surface.

27. The heat sink device according to claim 26, wherein said second direction is generally parallel to said depth direction.

28. The heat sink device according to any one of claims 25 to 27, wherein said thermal contact between said second thermal contact surface and said heat transfer body is defined along a first plane generally orthogonal to said depth direction.

29. The heat sink device according to any one of claims 26 to 28, wherein said heat transfer body comprises a third heat transfer surface and wherein said auxiliary heat transfer body comprises a fourth heat transfer surface, and wherein said auxiliary heat transfer element is movably mounted with respect to said heat transfer unit to concurrently provide thermal contact between said third thermal contact surface and said fourth thermal transfer surface.

30. The heat sink device according to claim 29, wherein said thermal contact between said third thermal contact surface and said fourth thermal transfer surface is defined along a second plane inclined to said first direction and to said second direction.

31. The heat sink device according to any one of claims 26 to 30, wherein said heat transfer element is in the form of at least one first wedge member movably accommodated in a recess formed in said heat transfer body to move with respect thereto along said first direction and wherein said auxiliary heat transfer element is in the form of a second wedge member movably engaged to said at least one first wedge member to concurrently move with respect thereto along said second direction, and wherein said first thermal contact surface is generally parallel to a heat transfer surface of the said at least one heat generating component, and wherein said second thermal transfer surface is inclined with respect to said first thermal contact surface.

32. The heat sink device according to claim 31, wherein said second thermal transfer 5 surface is orthogonally inclined with respect to said first thermal contact surface.

33. The heat sink device according to any one of claims 26 to 32, wherein said auxiliary heat transfer element is affixed to the at least one heat generating component, and wherein said auxiliary heat transfer element is reversibly movably engaged with respect to said first wedge member.

10 34. The heat sink device according to any one of claims 26 to 30, wherein said heat transfer unit comprises a plurality of first wedge members, each said first wedge member being movably accommodated in a respective recess formed in said heat transfer body to move with respect thereto along a respective said first direction and wherein said auxiliary heat transfer element is in the form of a second wedge member

15 movably engaged to each said first wedge member to concurrently move with respect thereto along said second direction, and wherein said first thermal contact surface is generally parallel to a heat transfer surface of the said at least one heat generating component, and wherein each respective said second thermal transfer surface of each said first wedge member is inclined with respect to said first thermal contact surface.

20 35. The heat sink device according to claim 34, wherein each said second thermal transfer surface is orthogonally inclined with respect to said first thermal contact surface.

36. The heat sink device according to any one of claims 34 to 35, wherein said auxiliary heat transfer unit is affixed to the at least one heat generating component, and

25 wherein said auxiliary heat transfer unit is reversibly movably engaged with respect to each respective said second wedge members.

37. The heat sink device according to any one of claims 1 to 36, wherein:

- said at least one heat generating component is chosen form a group including: any electronic component including a CPU; any other electronic device that during

30 operation thereof generates undesired thermal energy; and/or

- wherein said substrate is a PCB.

38. A conduction cooled module comprising:

a first said heat sink device as defined in any one of claims 1 to 37;

a substrate comprising at least one said heat generating component;

said heat transfer body being mounted to said substrate, said first thermal contact surface being in thermal contact with said at least one heat generating component, and said second thermal contact surface being in thermal contact with said heat transfer body.

39. The conduction cooled module according to claim 38, wherein the first said heat sink device is hermetically mounted to said circuit board to define a first internal space comprising said at least one said heat generating component mounted to said first face.

40. The conduction cooled module according to any one of claims 38 to 39, wherein said first thermal contact surface is in contact with said at least one heat generating component at a first spacing from said first face, and wherein said selective displacement of said heat transfer element allows said first spacing to be within a predetermined first spacing range while concurrently providing said thermal contact between said second thermal contact surface and said heat transfer body.

41. The conduction cooled module according to claim 40, wherein said predetermined first spacing range includes a variation in said first spacings provided by a plurality of alternative said heat generating component each of which can be alternately mounted to said first face and in thermal contact with said heat sink device via said heat transfer unit.

42. The conduction cooled module according to claim 41, wherein said variation in said first spacings at least partially originates from at least one of:

- undefined or variable manufacturing tolerances of the respective said heat generating components; and

- dimensional deviations from nominal of the respective mounting position of the respective said heat generating components on the said first face during mounting operation thereon.

43. The conduction cooled module according to any one of claims 41 to 42, wherein said variation in said first spacings include a range of between about 0mm and about lmm.

44. The conduction cooled module according to any one of claims 38 to 43, further 5 comprising a heat extraction arrangement in thermal contact with said conduction cooled module and configured for transferring heat away from said conduction cooled module via said first said heat sink device.

45. The conduction cooled module according to any one of claims 39 to 44, wherein said substrate comprises at least one heat generating component that is mounted to a

10 second face of said substrate, said second face and said first face facing each facing mutually opposite directions, and further comprising a second said heat sink device hermetically mounted to said circuit board to define a second internal space comprising said at least one said heat generating component mounted to said second first face.

46. The conduction cooled module according to any one of claims 38 to 45, 15 wherein:

- wherein said substrate is a PCB.

20 47. A method for assembling a conduction cooled module comprising:

(a) providing a first said heat sink device as defined in any one of claims 1 to 37;

(b) providing a substrate comprising at least one said heat generating component;

(c) mounting said heat transfer body to said substrate ensuring said first thermal contact surface is in thermal contact with said at least one heat generating

25 component, and said second thermal contact surface is in thermal contact with said heat transfer body.