Layered structure arrangement for thermal conduction for electronic components

Abstract

According to embodiments herein it is herein provided a layered structure arrangement (1) for thermal conduction for electronic components. The layered structure arrangement (1) comprises a first layer (2a) comprising a plurality of first modules (3a) arranged with a respective first space (4a) in between adjacent first modules (3a). The layered arrangement further comprises a second layer (2b) comprising a plurality of second modules (3b) arranged with a respective second space (4b) in between adjacent second modules (3b). The first layer (2a) and the second layer (2b) are arranged, upon applied pressure on said layered structure arrangement (1), to engage with one another such that a respective first module (3a) of the first layer (2a) slides into a corresponding second space (4b) in the second layer (2b), and a respective second module (3b) of the second layer (2b) slides into a corresponding first space (4a) in the first layer (2a), providing one or more thermal conducting transfer paths.

Description

[0001] LAYERED STRUCTURE ARRANGEMENT FOR THERMAL CONDUCTION FOR ELECTRONIC COMPONENTS

[0002] TECHNICAL FIELD

[0003] Embodiments herein relate in general to arrangements for thermal conduction when transferring heat from electronic components. Specifically, a layered structure arrangement for thermal conduction for electronic components is provided.

[0004] BACKGROUND

[0005] When it comes to thermal conduction for electronic components, different solutions are provided. Often thermal gap pads for transferring heat from a heatsupplying component such as an electronic device are used. Thermal gap pads are used in various devices to provide heat transfer between a heat-supplying component and a cooling structure such as a heat sink. These gap pads provide for improved physical contact between a heat-supplying component and a heat sink in order to conduct heat away from the component, by minimizing or removing any air gaps due to for example roughness of the contact surfaces. Gap pads are useful in devices where heat-supplying components may have various sizes and manufacturing tolerances that result in small gaps between the components and the heat sink. A gap pad can be inserted into the gap to accommodate such manufacturing tolerances and improve thermal conduction to the heat sink.

[0006] Both electrically isolating gap pads and non-isolating gap pads are provided today. One problem is that they are either too hard or have to high thermal resistance. Gap pads that are non-isolating are usually very hard. One important factor for a good thermal contact is contacting pressure and it has been shown that increasing the contact pressure decreases the thermal resistance. However, if a hard gap pad is employed there is a risk that components break during assembly if the contact pressure is too high, resulting in a lot of problems. To avoid breaking, softer gap pads may be used. Providing gap pads being soft without losing proper thermal abilities is difficult. Electrically isolating gap pads are often softer, but on the other side have high thermal resistance.

[0007] For a cooling solution, where heat is transported from hot region to cold through various materials, the contact resistance in each material-to-material interface limits the amount of heat being transported. In each interface the contact resistance is a function of the surface area and material properties. In an ideal situation the whole of a shared contacting area is transporting heat from one body to the other. The only limitation in such a case is the material properties of the bodies, respectively.

[0008] In reality, surface roughness and body imperfections hinder complete surface to surface contact, and a thermal resistance occurs. To reduce the thermal resistance thermal interface materials (TIM) are used. These are often soft whereby voids between bodies may be filled improving contact to ensure good thermal contact. A drawback of these TIMs is that they have low bulk thermal conductivity, thus introducing a resistance themselves.

[0009] SUMMARY

[0010] From what prior art disclose, there is a need for a solution providing low thermal resistance to achieve effective heat transferring and at the same time ensuring that sensitive components will not break during assembly, or use.

[0011] An object of embodiments herein is to increase a thermal conductivity of an interface material that is flexible.

[0012] According to an aspect of embodiments herein, the object is achieved by providing a layered structure arrangement for thermal conduction of electronic components. The layered structure arrangement comprises a first layer comprising a plurality of first modules arranged with a respective first space in between adjacent first modules. The layered structure arrangement further comprises a second layer comprising a plurality of second modules that are arranged with a respective second space in between adjacent second modules. The first layer and the second layer are arranged, upon applied pressure on the layered structure arrangement, to engage with one another such that a respective first module of the first layer slides into a corresponding second space in the second layer, and a respective second module of the second layer slides into a corresponding first space in the first layer providing one or more thermal conducting transfer paths.

[0013] In one or more of the respective first spaces a flexible first element may be arranged. Additionally, or alternatively, in one or more of the respective second spaces a respective flexible second element may be arranged. Such flexible elements may comprise a spring arrangement or similar. According to embodiments herein, upon the applied pressure on the layered structure arrangement, the respective first module of the first layer may flex a respective flexible second element in the corresponding second space in the second layer. The respective second module of the second layer may flex a respective flexible first element in the corresponding first space in the first layer providing an additional thermal conducting transfer path and / or a flexible performance of the layered structure arrangement.

[0014] According to embodiments herein, upon the applied pressure on the layered structure arrangement, the flexible elements of the first layer and the second layer may be spring loaded and thereby providing an improved (additional) contact pressure between the layered structure arrangement and one or more electronic components.

[0015] According to embodiments herein, the contact between side surfaces of the modules in the first layer and the second layer, respectively, when the two layers are engaged may provide for thermal conducting transfer paths.

[0016] According to embodiments herein, the side surfaces of the modules may have a tapered profile such that the two layers lock each other sideways when the pressure is applied on the layered structure arrangement.

[0017] According to embodiments herein, the tapered side surfaces may be arranged such that the contact pressure between the side surfaces are increased when the pressure applied on the layered structure arrangement is increased.

[0018] According to embodiments herein, the spaces in between the modules in respective layer may provide for the layered structure arrangement to deform when pressure is applied, thereby enabling the top surface and the bottom surface respectively, of the layered structure arrangement to conform to respective contact surface.

[0019] According to embodiments herein, the modules and spaces may be arranged in a respective engaging array in each layer.

[0020] According to embodiments herein, the layered structure arrangement may further comprise more than two layers wherein respective adjacent layers are arranged to engage with each other.

[0021] According to embodiments herein, the layered structure arrangement may be provided in metal. According to embodiments herein, the layered structure arrangement may be manufactured in a single piece.

[0022] Thus, embodiments herein provide a solution providing low thermal resistance to achieve effective heat transferring and at the same time ensuring that sensitive components will not break during assembly, or use.

[0023] BRIEF DESCRIPTION OF DRAWINGS

[0024] Fig. 1 shows an example of a layered structure arrangement. Fig. 2 also shows an exemplary embodiment of a layered structure arrangement.

[0025] In Fig. 3, details of an exemplary embodiment of a layered structure arrangement are shown.

[0026] In Fig. 4, a layered structure arrangement is shown when employed for thermal conduction of an electronic component.

[0027] In Fig. 5, a layered structure arrangement is shown in an exploded view when employed for thermal conduction of an electronic component.

[0028] Fig. 6 is a perspective view of a layered structure arrangement when employed for thermal conduction of an electronic component.

[0029] DETAILED DESCRIPTION

[0030] In Figs. 1-2, exemplary embodiments of a layered structure arrangement 1 for thermal conduction of electronic components are shown. The layered structure arrangement comprises a first layer 2a comprising a plurality of first modules 3a arranged with a respective first space 4a in between adjacent first modules 3a. In the respective first space 4a a flexible first element 6a may be arranged. A flexible element may be any suitable structure providing a flexing function, thus, although shown as a spring in exemplified embodiments herein, any other suitable shape of the element providing a flexible function may be used. Further it should be noted that a layer may be provided with or without flexible elements, and, if flexible elements are present in a layer, a single flexible element may be present as well as flexible elements being present in all spaces, or in some spaces. Further, note that in a layer, different types of flexible elements 6 may be present in different spaces 4a of the same layer. Thus, it should be noted that in one or more of the respective first spaces a flexible first element may be arranged. Additionally, or alternatively, in one or more of the respective second spaces a respective flexible second element may be arranged.

[0031] The layered structure arrangement further comprises a second layer 2b comprising a plurality of second modules 3b is arranged with a respective second space 4b in between adjacent second modules 3b. In the respective second space 4b a flexible second element 6b may be arranged. The first layer 2a and the second layer 2b are arranged, upon an applied pressure on the layered structure arrangement 1 , to engage with one another such that a respective first module 3a of the first layer 2a slides into a corresponding second space 4b in the second layer 2b, and a respective second module 3b of the second layer 2b slides into a corresponding first space 4a in the first layer 2a providing one or more thermal conducting transfer paths. Upon the applied pressure on the layered structure arrangement, the respective first module 3a of the first layer 2a may flex a respective flexible second element 6b in the corresponding second space 4b in the second layer 2b, and the respective second module 3b of the second layer 2b may flex a respective flexible first element 6a in the corresponding first space 4a in the first layer 2a, providing an additional thermal conducting transfer path and / or a flexible performance of the layered structure arrangement. Upon the applied pressure on the layered structure arrangement, the flexible elements 6a, 6b of the first layer and the second layer may be spring loaded and thereby provide an improved, or additional, contact pressure between the layered structure arrangement 1 and one or more electronic components.

[0032] Thus, in some embodiments, the layered structure arrangement 1 , in a plurality of said respective first spaces 4a, flexible first elements 6a may be arranged. Additionally, or alternatively, the layered structure arrangement 1 may be arranged, in a plurality of said respective second spaces 4b, flexible second elements 6b. The layered structure arrangement 1 may provide for contact between side surfaces 5a, 5b of the modules 3a, 3b in the first layer 2a and the second layer 2b, respectively, when the two layers 2a, 2b are engaged, and thereby providing effective thermal conducting transfer paths and effective cooling. Small sliding modules, or blocks, with sufficient contact in between themselves keep the thermal cross-section high when the gap pad is compressed during mounting in a system with electronic components.

[0033] As shown in Fig. 3, the side surfaces 5a, 5b have in the exemplified embodiment a tapered profile such that the two layers lock each other sideways when pressure is applied on the layered structure arrangement 1. The layered structure arrangement 1 may be arranged with the tapered side surfaces 5a, 5b such that the contact pressure between the side surfaces 5 are increased when the pressure applied on the layered structure arrangement 1 is increased, and thereby, improved or additional contact is provided between the surfaces and the heat transfer will be more efficient.

[0034] The spaces 4a, 4b in between the modules 3a, 3b in respective layer 2a, 2b may provide for the layered structure arrangement 1 to deform when pressure is applied. A top surface 7 and a bottom surface 8, respectively, of the layered structure arrangement 1 are thus enabled to conform to respective contact surface. As shown in the Figs. 1 and 2, the modules 3a, 3b and the corresponding spaces 4a, 4b, may be arranged in a respective engaging array in each layer 2a, 2b.

[0035] Transfer of heat is material dependent, and copper is one of the most favorable. Embodiments herein enable the use of metal as TIM. The layered structure arrangement 1 provides a structure adapting to connecting surfaces for cooling by providing a structure being flexible and acting as a spring. The heat transferring cross-section will be as large as possible during use. The layered structure arrangement disclosed herein may take up large tolerances in distance between surfaces to be connected for cooling. The layered structure arrangement 1 may be manufactured in various thickness, using a material that can allow for deformation, and yielding surface adaption as well as full recyclability.

[0036] The layered structure arrangement 1 may be manufactured in a single piece, or may be provided as separate layers assembled together. Although the exemplified embodiment shows two layers, the layered structure arrangement 1 may comprise more than two layers, where respective adjacent layers may be arranged to engage with each other.

[0037] The layered structure arrangement 1 can be provided in metal such as copper, in whole, or in part. The modules 3a, 3b may be provided as very many and small individual modules, such as blocks, of metal, each providing a transporting cross-section, and the possibility to adapt and conform to the surfaces which they will contact. Thanks to the layered structure arrangement, a flexible metal interface is provided. The interface is able to adapt to surfaces, and thereby significantly increase the amount of heat that can be transported away in order to cool components or the like.

[0038] The modules may be different shapes such as blocks, pillars, cones, spherical. The modules of the different layers may have same geometry properties, but may also have different shapes or forms. The modules may be solid shape with a dense or less dense structure, and / or the modules may have a more hollow structure. The modules of respective layer may be compressed such that during compression the areas under contact may undergo contacting deformation and enabling increasing contact pressure in between the modules. When the first layer 2a shown on top in the Fig. 3 is moved down by applied pressure / force, the modules 4a, 4b in the first and second layers start to meet and make contact.

[0039] The layered structure arrangement 1 may be made completely in metal, for example copper. The provided arrangement will improve the thermal performance and may be used in many applications. Thanks to the layered structure with the modules, it will adapt to different surfaces, such as different surface roughness, flatness, and other irregularities, and still maintaining its flexibility. The provided arrangement will be totally recyclable and thereby be very sustainable. Moreover, it will remove the need of many materials that are non-recyclable. The function of the layered structure arrangement 1 is to obtain a high thermal conducting cross-section area when a system in which it is employed is compressed. The thermal conductive path, from top to bottom, is intended to have the same, or larger cross-section in all points when the layered structure arrangement 1 is compressed and the layers 2a, 2b are engaged with each other. The respective layers 2a, 2b may comprise modules such as heat conducting structure modules and flexible elements such as spring structures. The layers 2a, 2b may be held together with the spring structures and I or deformation structures. The total amount of thermal cross-section may be decreased by >2 to % in order to allow for adaptability and spring-back in order to keep pressure on contacting areas.

[0040] When the layered structure arrangement 1 is compressed, and the movement continues, the pressure between the meeting modules 3a, 3b may increase. At the same time the shared thermal transfer area between the module connecting side surfaces may increase, and thereby an increased thermal contact may be created. Thereby, it is enabled to decrease the thermal resistance by smoothening due to pressure between contacting surfaces. The number of connecting surfaces may vary depending on the individual design of the layered structure arrangement.

[0041] Fig. 2 also shows an exemplary embodiment of the layered structure arrangement 1. The flexible elements 6a, 6b may be provided in different shapes and types, in the exemplified embodiment, a round shaped flexible element is shown, providing a flexing performance in multiple directions. It may be noted that flexing element of any other shape may be used, such as a spring or a V-shaped member. Both the flexing elements and the modules may be of metal, for example copper. The spring structure in between the modules or blocks may also act as deformation structures in X-Y direction assuming z-direction in the thickness direction and will assure that the contact between the modules or blocks are maintained.

[0042] In Fig. 3, details of an exemplary embodiment of a layered structure arrangement 1 is shown. The shown example have modules 3a, 3b or blocks with tapered sides or side surfaces 5a, 5b. Furthermore the top surface 7 and the bottom surface 8, respectively, of the layered structure arrangement 1 are shown.

[0043] One design parameters of the modules 3a, 3b in the exemplified design presented is the taper angle of the modules. The angle is responsible for the X-Y forces applied when the layered structure arrangement 1 is set under pressure, and also to some extent to the Z-force. If the angle is too large, the rebound will be good as there will be less friction between modules to push them apart, and the thermal transfer will be good, but the compression distance will be short, and the structure will act stiff. In the opposite, a large angle will cause high friction in the compression phase yielding movement difficulties. The angle will be dependent of material, design, and mating components surface friction of the electronic components such as a heatsink and a component. The balance between the angle and the flexible elements yields both thermal contacting pressure module to module contact , top and bottom pressure, as well as rebound function. With the flexible elements, for example being diamond shaped, the layered structure arrangement 1 will, when employed in a system, exert pressure on a heatsink as well as on a component, assuring thermal bridging across temperatures. The layered structure arrangement 1 may be built up from tapered or constant cross-sectional modules or blocks, interconnected with structures that may act as movement constraining and I or spring like functions. The shape of the modules or blocks may be of any applicable shape, square, rectangle, round, hexagon, octagon etc. The only limitations of different shapes relate to the thermal transfer area, which should be sufficiently large when the structured arrangement 1 is compressed.

[0044] As an alternative embodiment enabling spring-back effect of the flexible elements, increasing the contacting pressure, auxetic structures may be used instead of common spring designs. One advantage will be that such structures may collapse, and contract in certain directions with relatively low force needed. In Fig. 4, a layered structure arrangement 1 is shown when employed for thermal conduction of an electronic component comprised in a system. The system comprises a cover or lid 10, a TIM according to embodiments herein placed either on top of a component 11, below a printed circuit board (PCB) 12, or both, and a heat sink 9. TIM applications may generally be divided into three categories, TIM1 is inside the package, between die and lid, TIM1.5 for bare dies, without any lid, and placed between die and heat sink. TIM2 usually follows after TIM1 applications, inbetween lid and heat sink. The layered structure arrangement 1 may be used as TIM in any position, TIM1 , TIM1.5 or TIM2, thus being suitable for all thermal interfaces in the system. The component 11 may be cooled via the lid 10, or directly onto the PCB 12.

[0045] During mounting of the system, the layered structure arrangement 1 is compressed to ensure as good thermal contact as possible without breaking the component due to bending. Different arrangements may be used, placing the TIM 1 below the PCB 12, and placing the TIM 1 on top of the component 10. The TIM may also be placed on both sides, above the component 11 and below the PCB 12. The TIM 1 may exert some spring-back effect to ensure thermal contact.

[0046] In Fig. 5, the layered structure arrangement 1 is shown in an exploded view when employed for thermal conduction of the electronic component. In principal, the component 10 is present, and the heatsink 9, with either being on top and bottom or vice versa. In the middle there is the layered structure arrangement 1 acting as gap pad.

[0047] Fig. 6 is a perspective view of the layered structure arrangement 1 when employed for thermal conduction of an electronic component. The layered structure arrangement 1 is shown as mounted between the heatsink 9 and the component 10.

[0048] It will be appreciated that the foregoing description and the accompanying drawings represent non-limiting examples of the methods and apparatus taught herein. As such, the apparatus and techniques taught herein are not limited by the foregoing description and accompanying drawings. Instead, the embodiments herein are limited only by the following claims and their legal equivalents.

Claims

CLAIMS1 . A layered structure arrangement (1 ) for thermal conduction for electronic components, wherein said layered structure arrangement (1 ) comprises: a first layer (2a) comprising a plurality of first modules (3a) arranged with a respective first space (4a) in between adjacent first modules (3a), and a second layer (2b) comprising a plurality of second modules (3b) arranged with a respective second space (4b) in between adjacent second modules (3b); and wherein the first layer (2a) and the second layer (2b) are arranged, upon applied pressure on said layered structure arrangement 1 , to engage with one another such that a respective first module (3a) of the first layer (2a) slides into a corresponding second space (4b) in the second layer (2b), and a respective second module (3b) of the second layer (2b) slides into a corresponding first space (4a) in the first layer (2a), providing one or more thermal conducting transfer paths.

2. The layered structure arrangement (1 ) according to claim 1 , wherein, in at least one of said respective first space (4a), a flexible first element (6a) is arranged.

3. The layered structure arrangement (1 ) according to the preceding claim, wherein, upon applied pressure on said layered structure arrangement, the respective second module (3b) of the second layer (2b) flexes said at least one flexible first element (6a) in the corresponding first space (4a) in the first layer (2a), providing an additional thermal conducting transfer path and / or a flexible performance of the layered structure arrangement.

4. The layered structure arrangement (1 ) according to any of the preceding claims, wherein, in at least one of said respective second space (4b), a flexible second element (6b) is arranged, providing an additional thermal conducting transfer path and / or a flexible performance of the layered structure arrangement.

5. The layered structure arrangement (1 ) according to the preceding claim, wherein, upon applied pressure on said layered structure arrangement, the respective firstmodule (3a) of the first layer (2a) flexes a said at least one flexible second element (6b) in the corresponding second space (4b) in the second layer (2b).

6. The layered structure arrangement (1 ) according to any of claims 2 - 5, wherein, upon applied pressure on said layered structure arrangement, said flexible elements (6a, 6b) of the first layer and the second layer are spring loaded and thereby provides an improved contact pressure between the layered structure arrangement (1 ) and one or more electronic components.

7. The layered structure arrangement (1 ) according to any of the preceding claims, wherein contact between side surfaces (5a, 5b) of the modules (3a, 3b) in the first layer (2a) and the second layer (2b), respectively are provided, when the two layers (2a, 2b) are engaged thereby providing thermal conducting transfer paths.

8. The layered structure arrangement (1 ) according to the preceding claim, wherein said side surfaces (5a, 5b) have a tapered profile such that the two layers lock each other sideways when pressure is applied on the layered structure arrangement (1 ).

9. The layered structure arrangement (1 ) according to the preceding claim, wherein said tapered side surfaces (5a, 5b) are arranged such that the contact pressure between the side surfaces (5a, 5b) are increased when the pressure applied on the layered structure arrangement (1) is increased.

10. The layered structure arrangement (1 ) according to any of the preceding claims, wherein the spaces (4a, 4b) in between the modules (3a, 3b) in respective layer (2a, 2b) provide for the layered structure arrangement (1) to deform when pressure is applied, thereby enabling a top surface (7) and a bottom surface (8), respectively, of the layered structure arrangement (1 ) to conform to respective contact surface.11 . The layered structure arrangement (1 ) according to any of the preceding claims, wherein said modules (3a, 3b) and spaces (4a, 4b) are arranged in a respective engaging array in each layer (2a, 2b).

12. The layered structure arrangement (1 ) according to any of the preceding claims, further comprising more than two layers (2), wherein respective adjacent layers are arranged to engage with each other.

13. The layered structure arrangement (1 ) according to any of the preceding claims, wherein the layered structure arrangement is provided in metal.

14. The layered structure arrangement (1 ) according to any of the preceding claims, wherein the layered structure arrangement (1 ) is manufactured in a single piece.

15. The layered structure arrangement (1 ) according to any of claims 1 -14, wherein each layer of the layered structure arrangement (1 ) is manufactured as a separate piece.

16. The layered structure arrangement (1 ) according to any of the preceding claims, wherein, in a plurality of said respective first spaces (4a), flexible first elements (6a) are arranged.

17. The layered structure arrangement (1 ) according to any of the preceding claims, wherein, in a plurality of said respective second spaces (4b), flexible second elements (6b) are arranged.

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