Cooling assembly with heat spreaders

Abstract

The disclosure relates to a cooling assembly (100), comprising: an electronic package (110) with a first heat dissipation area (110a) and a second heat dissipation area (110b), wherein a heat dissipation measure of the first heat dissipation area is lower than a heat dissipation measure of the second heat dissipation area; a first heat spreader (120a) placed above the first heat dissipation area; a second heat spreader (120b) placed above the second heat dissipation area; and a heat sink (130a, 130b) placed on the first heat spreader and the second heat spreader, the heat sink being configured to dissipate heat received via the first and second heat spreaders from the first and second heat dissipation areas of the electronic package; wherein the first heat spreader and the second heat spreader are separated by a gap (123), the gap being configured to reduce heat transfer between the first heat spreader and the second heat spreader.

Description

[0001] COOLING ASSEMBLY WITH HEAT SPREADERS

[0002] TECHNICAL FIELD

[0003] The disclosure relates to the field of thermal dissipation and heat diffusion. In particular, the disclosure relates to a cooling assembly with heat spreaders for cooling an electronic package. More particularly, the disclosure relates to double vapor chamber cooling assembly for multi-specification chips.

[0004] BACKGROUND

[0005] One of the common designs of electronic package is the chip with high power component and low power component placed closely to each other. Such two kinds of components have significantly different operation features, especially low-power component (1stheater) dissipates low amount of heat, but requires relatively low operation temperature, and high-power component (2ndheater) generates much larger amount of heat but can operate at higher temperatures compared to 1stheater. Traditional cooling scheme is coupling of chips with heat spreader (such as vapor chamber) having heat sink. But in such a case, the temperature of vapor chamber will be high due to receiving and transferring large amount of heat from 2ndheater to heat sink. So, the temperature of spreader appropriate for cooling of 2ndheater will not be suitable for cooling of 1stheater, even if power of 1stheater is low.

[0006] SUMMARY

[0007] This disclosure provides a solution for an efficient cooling of a multi-specification electronic package as described above, i.e., an electronic package having low-power component (1stheater) and high-power component (2ndheater).

[0008] In particular, the disclosure provides a solution for cooling of coupled chip (or package) having zones with different temperature specification and placed closely to each other.

[0009] The disclosure provides a solution for a cooling scheme which allows to organize heat dissipation from powerful composite chips (or package) having zones with significantly different thermal requirements.

[0010] The foregoing and other objects are achieved by the features of the independent claims. Further implementation forms are apparent from the dependent claims, the description and the figures.

[0011] Aspects of the present disclosure provide a cooling assembly with two or more heat spreaders for efficient cooling of a multispecification electronic chip or electronic package. The cooling assembly is based on a separate cooling concept, where specific heat spreaders with specific heat sinks or common heat sink are used for cooling of 1stheater and cooling of 2ndheater. Cold coolant is supplied firstly to the 1stpart of cooling assembly and then flows with larger temperature to 2ndpart of cooling assembly. Alternatively, coolant can be supplied to the 1stand 2ndpart of cooling assembly, and coolant supplied to the 1stpart of cooling assembly has smaller temperature than coolant supplied to the 2ndpart of cooling assembly. In ideal case, no heat exchange happens between the two parts of cooling assembly. The disclosure presents solutions for improving mechanical structure of such a cooling assembly without significantly affecting thermal performance of separate cooling.

[0012] In order to describe the disclosure in detail, the following terms and notations will be used. HS Heat sink

[0013] VC Vapor chamber

[0014] HTC Heat transfer coefficient

[0015] PCB Printed Circuit Board

[0016] According to a first aspect, the disclosure relates to a cooling assembly, comprising: an electronic package with a first heat dissipation area and a second heat dissipation area, wherein a heat dissipation measure of the first heat dissipation area is lower than a heat dissipation measure of the second heat dissipation area; a first heat spreader placed above the first heat dissipation area; a second heat spreader placed above the second heat dissipation area; and a heat sink placed on the first heat spreader and the second heat spreader, the heat sink being configured to dissipate heat received via the first and second heat spreaders from the first and second heat dissipation areas of the electronic package; wherein the first heat spreader and the second heat spreader are separated by a gap, the gap being configured to reduce heat transfer between the first heat spreader and the second heat spreader.

[0017] Such a cooling assembly provides efficient cooling of multi-specification electronic packages or chips, i.e., of electronic packages or chips having low-power component (1stheater) and high-power component (2ndheater). The cooling assembly particular provides an efficient cooling of coupled chips or packages which have zones with different temperature specification and placed closely to each other.

[0018] The term “heat dissipation measure” may describe a temperature (T). In this case first heat dissipation has lower T means lower heat dissipation measure. The term “heat dissipation measure” may also describe a power of generated heat. In this case, first heat dissipation has a lower power means that first dissipation will have less dissipated power.

[0019] In an exemplary implementation of the cooling assembly, the first heat spreader is configured for a lower temperature than the second heat spreader.

[0020] Such a cooling assembly allows to organize heat dissipation from powerful composite chips or packages having zones with significantly different thermal requirements.

[0021] In an exemplary implementation of the cooling assembly, the first heat spreader comprises a first main surface facing the first heat dissipation area; wherein a first contact area is formed on a section of the first main surface, the first contact area contacting the first heat dissipation area; and the second heat spreader comprises a first main surface facing the second heat dissipation area; wherein a first contact area is formed on a section of the first main surface, the first contact area contacting the second heat dissipation area.

[0022] When the first / second contact area is formed on a section of the first main surface of the first / second heat spreader, the heat spreader can extend to a larger size than the size of the contact area thereby improving heat dissipation.

[0023] In an exemplary implementation of the cooling assembly, the first contact area of the first heat spreader is arranged at a side of the first heat spreader facing the second heat spreader; and the first contact area of the second heat spreader is arranged at a side of the second heat spreader facing the first heat spreader. By arranging the first contact area of the first / second heat spreader at a side of the first / second heat spreader facing the second / first heat spreader, a compact design of the package or chip can be implemented with improved heat dissipation characteristics.

[0024] In an exemplary implementation of the cooling assembly, the first contact area of the first heat spreader is arranged at a middle section or at a comer section of the side of the first heat spreader facing the second heat spreader; and the first contact area of the second heat spreader is arranged at a middle section or at a comer section of the side of the second heat spreader facing the first heat spreader.

[0025] This provides design flexibility. Depending on the chip or package design, appropriate heat spreaders can be attached to the chip / package.

[0026] The first contact area of the first heat spreader may, for example, have a larger or equal size as the first contact area of the second heat spreader. In some examples, it may also have a smaller size.

[0027] In an exemplary implementation of the cooling assembly, for each of the heat spreaders a number of contact areas is greater than one; and / or the contact areas for each of the heat spreaders are arranged at a side or at a comer section of the respective heat spreader.

[0028] When having a high number of contact areas, the heat spreaders can efficiently cool the chip or package.

[0029] In an exemplary implementation of the cooling assembly, the heat sink comprises a first section and a second section which are separated from each other by the same gap or another gap.

[0030] When the heat sink has two sections, cooling of the different cooling zones can be efficiently achieved and no heat exchange happens between the two part of the cooling assembly.

[0031] In an exemplary implementation of the cooling assembly, the cooling assembly is configured to use a coolant for cooling the cooling assembly; wherein the coolant enters firstly the first section of the heat sink and then enters the second section of the heat sink; and / or wherein the coolant entering the first section of the heat sink has a temperature smaller than a temperature of the coolant entering the second section of the heat sink.

[0032] Alternatively, coolant can be supplied to the 1stand 2ndpart of cooling assembly, and coolant supplied to the 1stpart of cooling assembly has smaller temperature than coolant supplied to the 2ndpart of cooling assembly.

[0033] Such a cooling assembly can implement an efficient cooling of the multi-specification chip or package by a single coolant.

[0034] In an exemplary implementation of the cooling assembly, the cooling assembly comprises: a supporting plate supporting the first heat spreader and the second heat spreader, wherein the supporting plate comprises a hole; wherein the first heat dissipation area and the second heat dissipation area are arranged inside the hole.

[0035] Such supporting plate provides mechanical stability of the cooling assembly and improved thermal performance of separated cooling of the multi-specification chip or package. In an exemplary implementation of the cooling assembly, the hole of the supporting plate is open to one side or two sides of the first heat spreader and the second heat spreader.

[0036] The hole can be adequately designed depending on the design of the package or chip.

[0037] In an exemplary implementation of the cooling assembly, the supporting plate comprises a plurality of holes, wherein each hole is configured to accommodate one or more heat dissipation areas of neighboring heat spreaders which are separated by respective gaps.

[0038] Such a design improves cooling performance.

[0039] In an exemplary implementation of the cooling assembly, a circumference of each hole is configured to surround contact areas contacting the respective one or more heat dissipation areas of the neighboring heat spreaders.

[0040] In such a design, the heat dissipation areas of the package of chip can be optimally placed in the holes of the supporting plate in order to achieve optimal heat transfer.

[0041] An outline of the supporting plate may be, for example, larger or smaller than a common outline of the first heat spreader and the second heat spreader.

[0042] In an exemplary implementation of the cooling assembly, the cooling assembly comprises: one or more bridges within the gap, the one or more bridges being configured to mechanically connect the first heat spreader with the second heat spreader.

[0043] These bridges can improve mechanical stability of the cooling assembly.

[0044] In an exemplary implementation of the cooling assembly, the one or more bridges between the first heat spreader and the second heat spreader are arranged within the gap outside a common outline of the first heat dissipation area and the second dissipation area.

[0045] By such design, the mechanical stability by the bridges is not affecting separate cooling of the two heat dissipation areas.

[0046] In an exemplary implementation of the cooling assembly, the supporting plate comprises a bridge section that is arranged along the gap between the first and second heat spreaders outside the contact areas of the heat spreaders.

[0047] This bridge section is different from the above bridges. In the bridge section or bridge area, heat transfer between the heat dissipation areas and the heat spreaders will occur.

[0048] In an exemplary implementation of the cooling assembly, the bridge section of the supporting plate comprises a fin or pin structure attached to one or both sides of the supporting plate.

[0049] This fin or pin structure improves heat transfer rate between the bridge section of the supporting plate and ambient, so the heat from spreaders transfers to the ambient through the bridge section of supporting plate instead of leaking from one heat spreader to another heat spreader, and therefore cooling performance of cooling assembly is improved. In an exemplary implementation of the cooling assembly, the cooling assembly comprises; a gap between the bridge section of the supporting plate and the first and second heat spreaders, the gap being configured to reduce heat transfer between the bridge section and the heat spreaders.

[0050] The gap between bridge section of supporting plate and heat spreaders is the gap (e.g., air gap or gas gap) with low thermal conductivity, so the heat transfer is reduced.

[0051] In an exemplary implementation of the cooling assembly, the bridge section of the supporting plate comprises a layered material stack with an internal material layer being absent or being empty space or being filled by a low thermal conductivity material or being filled by a porous material.

[0052] Such a layered material stack is easy to produce and can provide an efficient reduction of heat transfer between spreaders.

[0053] In an exemplary implementation of the cooling assembly, the bridge section of the supporting plate is extended to the first heat spreader or to the second head spreader or to both, the first and the second head spreaders.

[0054] This provides design flexibility.

[0055] In an exemplary implementation of the cooling assembly, the first heat spreader comprises a first vapor chamber for spreading heat from the first heat dissipation area and the second heat spreader comprises a second vapor chamber for spreading heat from the second heat dissipation area; wherein the first vapor chamber comprises a first evaporator placed above the first heat dissipation area and the second vapor chamber comprises a second evaporator placed above the second heat dissipation area; wherein the first evaporator and the second evaporator are separated by the gap, the gap being configured to suppress heat transfer between the first evaporator and the second evaporator.

[0056] Such a vapor chamber design can be easily produced and provides efficient heat spreading and cooling performance.

[0057] In an exemplary implementation of the cooling assembly, each of the first evaporator and the second evaporator comprises a top wall, a bottom wall and a side wall, the side wall connecting the top wall with the bottom wall; wherein the side wall of the first evaporator is separated from the side wall of the second evaporator by the gap; wherein at least one of the top wall, the bottom wall and the side wall are covered by a porous structure; wherein the porous structure on the bottom wall of the first and second evaporators comprises a porous fin structure with longitudinal fins extending from the side walls of the first and second evaporators to the contact areas of the heat spreaders.

[0058] Such a design provides efficient separation of the two heaters improving cooling efficiency.

[0059] In an exemplary implementation of the cooling assembly, the porous structure is absent near the one or more bridges.

[0060] This results in improved separation for cooling the first heater and for cooling the second heater.

[0061] In an exemplary implementation of the cooling assembly, the porous structure near the one or more bridges of the first vapor chamber has a larger pore size than the porous structure near the one or more bridges of the second vapor chamber. By such feature, reduction of heat transfer between spreaders is achieved.

[0062] In an exemplary implementation of the cooling assembly, the porous structure near the one or more bridges of the first vapor chamber has a larger pore size than the porous structure in areas of the first vapor chamber adjacent thereto; and the porous structure near the one or more bridges of the second vapor chamber has a smaller pore size than the porous structure in areas of the second vapor chamber adjacent thereto.

[0063] By such feature, reduction of heat transfer between spreaders is achieved.

[0064] According to a second aspect, the disclosure relates to a method for producing a cooling assembly, the method comprising: providing an electronic package with a first heat dissipation area and a second heat dissipation area, wherein a heat dissipation measure of the first heat dissipation area is lower than a heat dissipation measure of the second heat dissipation area; placing a first heat spreader above the first heat dissipation area; placing a second heat spreader above the second heat dissipation area; and placing a heat sink on the first heat spreader and the second heat spreader, the heat sink dissipating heat received via the first and second heat spreaders from the first and second heat dissipation areas of the electronic package; wherein the first heat spreader and the second heat spreader are separated by a gap to reduce heat transfer between the first heat spreader and the second heat spreader.

[0065] Such method allows efficient production of a cooling assembly as described above with respect to the first aspect with a gap for precisely separating the first heat spreader from the second heat spreader and therefore providing efficient cooling of the electronic package.

[0066] The method allows manufacturing a cooling assembly with superior cooling of multi-specification electronic packages or chips, i.e., of electronic packages or chips having low-power component (1stheater) and high-power component (2ndheater). The method allows producing a cooling assembly with efficient cooling of coupled chips or packages which have zones with different temperature specification and placed closely to each other.

[0067] BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Further embodiments of the disclosure will be described with respect to the following figures, in which:

[0069] Figure 1 shows a schematic diagram illustrating a side view of an exemplary cooling assembly 100 according to the disclosure with first option (Optl) and second option (Opt2) of coolant supplying scheme;

[0070] Figure 2 shows a schematic diagram illustrating top views on the cooling assembly 100 of Figure 1 with different examples for location and shape of contact areas;

[0071] Figure 3 shows a schematic diagram illustrating top views on the cooling assembly 100 of Figure 1 with different examples for location and shape of contact areas; Figure 4 shows a schematic diagram illustrating two cross sections 410, 420 of the cooling assembly 100 of Figure 1 with supporting plate 401, the top picture shows cross section 410 of the chip area while the bottom picture shows cross section 420 outside chip area;

[0072] Figure 5 shows a top view 510 on an exemplary supporting plate 401, a top view 520 on an exemplary configuration of two heat spreaders and a top view 530 on a cooling assembly 100 with such supporting plate 401 and heat spreaders configuration;

[0073] Figure 6 shows a top view 610 on an exemplary cooling assembly 100 with an exemplary shape of supporting plate 401 and configuration of heat spreaders;

[0074] Figure 7 shows a top view 710 on an exemplary supporting plate 401, a top view 720 on an exemplary configuration of two heat spreaders and a top view 730 on a cooling assembly 100 with such supporting plate 401 and heat spreaders configuration;

[0075] Figure 8 shows a top view 810 on an exemplary cooling assembly 100 with an exemplary shape of supporting plate 401 and configuration of heat spreaders;

[0076] Figure 9 shows a top view 910 on an exemplary cooling assembly 100 with an exemplary shape of supporting plate 401 and configuration of heat spreaders;

[0077] Figure 10 shows a top view 1010 on an exemplary cooling assembly 100 with an exemplary shape of supporting plate 401 and configuration of heat spreaders as well as exemplary fin 1001 and pin 1002 structures on the bridge area 403 of supporting plate;

[0078] Figure 11 shows top views 1110, 1120, 1130 on an exemplary cooling assembly 100 with exemplary configurations for bridge area;

[0079] Figure 12 shows a schematic diagram illustrating two cross sections of an exemplary cooling assembly 1200 comprising vapor chambers and exemplary supporting plate 401 having different structures 403, 404, the top picture shows cross section of the chip area while the bottom picture shows cross section outside chip area;

[0080] Figure 13 shows a top view of an exemplary evaporator 1300 of a vapor chamber of a cooling assembly 1200 according to the disclosure and two different cross sections of the evaporator in the bottom pictures;

[0081] Figure 14 shows a top view of an exemplary cooling assembly 1400 where two vapor chambers are connected directly by small bridges and three different cross sections of the cooling assembly 1200 in the bottom pictures;

[0082] Figure 15 shows a side view of an exemplary cooling assembly 1500 where the package or chip has a power map with nonregular heat dissipation and temperature requirements;

[0083] Figure 16 shows a 3D view, a cross section and a longitudinal section of an exemplary cooling assembly 1600 with two heat spreaders and supporting plate; Figure 17 shows a 3D view, a cross section and a longitudinal section of the supporting plate of the cooling assembly 1600 shown in Figure 16; and

[0084] Figure 18 shows a 3D view, a cross section and a plane section of an exemplary evaporator 1300 of a vapor chamber of a cooling assembly according to the disclosure.

[0085] DETAILED DESCRIPTION OF EMBODIMENTS

[0086] In the following detailed description, reference is made to the accompanying drawings, which form a part thereof, and in which is shown by way of illustration specific aspects in which the disclosure may be practiced. It is understood that other aspects may be utilized and structural or logical changes may be made without departing from the scope of the disclosure. The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the disclosure is defined by the appended claims.

[0087] It is understood that comments made in connection with a described method may also hold true for a corresponding device or system configured to perform the method and vice versa. For example, if a specific method step is described, a corresponding device may include a unit to perform the described method step, even if such unit is not explicitly described or illustrated in the figures. Further, it is understood that the features of the various exemplary aspects described herein may be combined with each other, unless specifically noted otherwise.

[0088] In the following, vapor chambers and heat pipes according to the disclosure are described.

[0089] Heat pipes and Vapor Chambers are two-phase devices used as thermal management solutions. A heat pipe is a device with high thermal conductance that can transport large amounts of heat with a slight temperature difference between its hot and cold ends. On the other hand, a Vapor Chamber is composed of flat heat pipes with very high thermal conductance, having flat surfaces on the top and bottom sides. Compared to traditional solutions like copper heat spreaders, heat pipes and Vapor Chambers have many advantages. In particular, they have a higher thermal conductivity, and the density of the heat pipe and Vapor Chamber is much lower than that of copper. Because of its hollow structure, the heat spreaders made by Vapor Chambers are much lighter than those made of copper. These properties make them stand out as ideal thermal management solutions.

[0090] A heat pipe, consisting of a working fluid, a wick structure, and an envelope, absorbs heat from its one end installed to the heat source when the working fluid evaporates as latent heat. The working fluid that has moved to the low-temperature section condenses and returns to liquid while releasing heat. The working fluid that is now liquid then returns toward the heat source due to capillary action. A heat pipe is made of metal with high thermal conductance containing a small amount of working fluid, like pure water, sealed. The pipe is altered to have a wick and uses a combination of evaporation and condensation of this working fluid to transfer heat efficiently. It transfers heat quickly and continuously without applying of additional external power.

[0091] A Vapor Chamber operates by the same principles as heat pipes. It has a metal enclosure that is vacuum sealed, an internal wick structure installed inside, and a working fluid that moves within the system thanks to capillary action. The heat source makes direct contact with a portion of the Vapor Chamber and a finned heat sink attached to the top. Some of the working fluid vaporizes and flows to cooler areas. Heat absorption causes the vapor to condense and return to liquid which is reabsorbed by the wick structure and distributed to the heat source.

[0092] As for the most common configuration, a Vapor Chamber houses vapor within a chamber instead of a pipe. The Vapor Chamber is a planar heat pipe, which can spread heat in two dimensions, using its entire body to cool the heat source. Its flat structure allows heat to be transferred evenly through a very small space. A Vapor Chamber can be imagined as a flat heat pipe in such a sense. Vapor Chambers are usually composed of thin plates having precisely formed grooves and a wick structure sealed together. They are also filled with a small amount of fluid, such as de-ionized water, just like heat pipes, which allow heat to be dispersed away from the source. The cooling efficiency of heat pipes is reduced when the pipes are bent or thinned because of its structure. But Vapor Chambers can be thinned to about 0.25 - 0.2 mm thickness.

[0093] Figure 1 shows a schematic diagram illustrating a side view of an exemplary cooling assembly 100 according to the disclosure with first option (Optl) and second option (Opt2) of coolant supplying scheme.

[0094] Thermo-coupling according to a first option (Optl , dotted line arrow) can be used for air cooling of the electronic package 110 (or chip). In such a coolant supplying scheme, an air flow 141, 142 is led by the heat sink 130a, 130b for cooling the heat sink 130a, 130b and thus the cooling assembly 100. A fan (not shown) can be used, for example, for generating the air flow 141, 142 from an ambient. It understands that any other suitable gas instead of air can be applied for this coolant supplying scheme, for example when operating the cooling assembly 100 under a closed atmosphere.

[0095] Thermo-coupling according to a second option (Opt2, solid line arrow) can be used for liquid cooling of the electronic package 110 (or chip). In such a coolant supplying scheme, a liquid flow 141, 142, e.g., in a cooling channel, is led by the heat sink 130a, 130b for liquid cooling the heat sink 130a, 130b and thus the cooling assembly 100. The liquid flow 141, 142 can, for example, be cooled in a heat exchanger (not shown) that can be connected to an air circulation comprising a fan (not shown) for generating an air flow from an ambient for cooling the liquid flow in the heat exchanger. The heat sink 130a, 130b may have different parts which may be cooled by separate liquid cooling circuits.

[0096] The cooling assembly 100 comprises an electronic package 110 with a first heat dissipation area 110a and a second heat dissipation area 110b, wherein a heat dissipation measure of the first heat dissipation area 110a is lower than a heat dissipation measure of the second heat dissipation area 110b.

[0097] The cooling assembly 100 comprises a first heat spreader 120a placed above the first heat dissipation area 110a; and a second heat spreader 120b placed above the second heat dissipation area 110b.

[0098] The cooling assembly 100 comprises a heat sink 130a, 130b placed on the first heat spreader 120a and the second heat spreader 120b. The heat sink 130a, 130b is configured to dissipate heat received via the first and second heat spreaders 120a, 120b from the first and second heat dissipation areas 110a, 110b of the electronic package 110.

[0099] The first heat spreader 120a and the second heat spreader 120b are separated by a gap 123 as can be seen from Figure 1. The gap 123 is configured to reduce heat transfer between the first heat spreader 120a and the second heat spreader 120b. The term “heat dissipation measure” may describe a temperature (T). In this case first heat dissipation has lower T means lower heat dissipation measure. The term “heat dissipation measure” may also describe a power of generated heat. In this case, first heat dissipation has a lower power means that first dissipation will have less dissipated power.

[0100] The first heat spreader 120a may be configured for a lower temperature than the second heat spreader 120b.

[0101] The first heat spreader 120a may comprise a first main surface 121a facing the first heat dissipation area 110a as shown in Figure 2, for example. A first contact area 122a as shown in Figures 2 and 3, for example may be formed on a section of the first main surface 121a. The first contact area 122a is contacting the first heat dissipation area 110a.

[0102] Analogously, the second heat spreader 120b may comprise a first main surface 121b facing the second heat dissipation area 110b as shown in Figure 2, for example. A first contact area 122b as shown in Figures 2 and 3, for example may be formed on a section of the first main surface 121b of the second heat spreader 120b. The first contact area 122b is contacting the second heat dissipation area 110b.

[0103] The first contact area 122a of the first heat spreader 120a may be arranged at a side 123a of the first heat spreader 120a facing the second heat spreader 120b as shown in Figure 2, for example.

[0104] The first contact area 122b of the second heat spreader 120b may be arranged at a side 123b of the second heat spreader 120b facing the first heat spreader 120a as shown in Figure 2, for example.

[0105] The first contact area 122a of the first heat spreader 120a may be arranged at a middle section 124a or at a comer section 125a of the side 123a of the first heat spreader 120a facing the second heat spreader 120b as shown in Figure 2, for example.

[0106] The first contact area 122b of the second heat spreader 120b may be arranged at a middle section 124b or at a comer section 125b of the side 123b of the second heat spreader 120b facing the first heat spreader 120a as shown in Figure 2, for example.

[0107] The first contact area 122a of the first heat spreader 120a may, for example, have a larger or equal size as the first contact area 122b of the second heat spreader 120b. In some example, it may also have a smaller size.

[0108] For each of the heat spreaders 120a, 120b a number of contact areas 122a, 126a, 122b, 126b as shown in Figures 2 and 3, for example can be greater than one.

[0109] The contact areas 122a, 126a, 122b, 126b for each of the heat spreaders 120a, 120b can be arranged at a side 123a, 123b or at a comer section 125a, 125b of the respective heat spreader 120a, 120b as shown in Figures 2 and 3, for example.

[0110] The heat sink 130a, 130b may comprise a first section 130a and a second section 130b which are separated from each other by the same gap 123 or another gap as shown in Figures 2 and 3, for example.

[0111] The cooling assembly 100 may be configured to use a coolant for cooling the cooling assembly 100.

[0112] The coolant 141, 142 may firstly enter the first section 130a of the heat sink and may then enter the second section 130b of the heat sink. io The coolant 141 entering the first section 130a of the heat sink may have a temperature smaller than a temperature of the coolant 142 entering the second section 130b of the heat sink.

[0113] As described above, thermo-coupling according to the first option (Optl, dotted line arrow) can be applied where the coolant 141, 142 is an air flow which is led by the heat sink 130a, 130b for cooling the two sections 130a, 130b of the heat sink and thus the cooling assembly 100. Alternatively (or additionally), thermo-coupling according to the second option (Opt2, solid line arrow) can be applied where the coolant 141, 142 is a liquid flow which is led, e.g., in a cooling channel, for liquid cooling the two sections 130a, 130b of the heat sink and thus the cooling assembly 100.

[0114] The cooling assembly 100 may comprise a supporting plate 401 supporting the first heat spreader 120a and the second heat spreader 120b as shown in Figure 4, for example. The supporting plate 401 may comprise a hole 402; wherein the first heat dissipation area 110a and the second heat dissipation area 110b may be arranged inside the hole 402 as shown in Figure 4, for example.

[0115] The hole 402 of the supporting plate 401 can be open to one side or two sides of the first heat spreader 120a and the second heat spreader 120b as shown in Figures 5 to 10, for example.

[0116] The supporting plate 401 may comprise a plurality of holes 402, wherein each hole 402 can be configured to accommodate one or more heat dissipation areas 110a, 110b of neighboring heat spreaders 120a, 120b which are separated by respective gaps 123.

[0117] A circumference of each hole 402 may be configured to surround contact areas 122a, 126a, 122b, 126b contacting the respective one or more heat dissipation areas 110a, 110b of the neighboring heat spreaders 120a, 120b.

[0118] An outline of the supporting plate 401 may be, for example, larger or smaller than a common outline of the first heat spreader 120a and the second heat spreader 120b.

[0119] The cooling assembly 100 may comprise one or more bridges 127a, 127b within the gap 123, the one or more bridges 127a, 127b being configured to mechanically connect the first heat spreader 120a with the second heat spreader 120b as shown in Figure 14, for example.

[0120] The one or more bridges 127a, 127b between the first heat spreader 120a and the second heat spreader 120b may be arranged within the gap 123 outside a common outline of the first heat dissipation area 110a and the second dissipation area 100b.

[0121] The supporting plate 401 may comprise a bridge section 403 that is arranged along the gap 123 between the first and second heat spreaders 120a, 120b outside the contact areas 122a, 122b, 126a, 126b of the heat spreaders 120a, 120b as shown in Figures 10 to 12 and 16 to 17, for example.

[0122] The bridge section 403 of the supporting plate 401 may comprise a fin 1001 or pin 1002 structure attached to one or both sides of the supporting plate 401 as shown in Figure 10, for example. The cooling assembly 100 may comprise a gap between the bridge section 403 of the supporting plate 401 and the first and second heat spreaders 120a, 120b. This gap is configured to reduce heat transfer between the bridge section 403 and the heat spreaders 120a, 120b.

[0123] The gap between bridge section 403 of supporting plate 401 and heat spreaders 120a, 120b can be the gap (e.g., air gap or gas gap) with low thermal conductivity, so the heat transfer is reduced.

[0124] The bridge section 403 of the supporting plate 401 may comprise a layered material stack with an internal material layer being absent or being empty space or being filled by a low thermal conductivity material or being filled by a porous material.

[0125] The bridge section 403 of the supporting plate 401 may be extended to the first heat spreader 120a or to the second head spreader 120b or to both, the first and the second head spreaders 120a, 120b.

[0126] The first heat spreader 120a may comprise a first vapor chamber 1520a for spreading heat from the first heat dissipation area 110a and the second heat spreader 120b may comprise a second vapor chamber 1520b for spreading heat from the second heat dissipation area 110b as shown in Figures 14 and 15, for example.

[0127] The first vapor chamber 1520a may comprise a first evaporator 1521a placed above the first heat dissipation area 110a and the second vapor chamber 1520b may comprises a second evaporator 1521b placed above the second heat dissipation area 110b as shown in Figure 15, for example.

[0128] The first evaporator 1521a and the second evaporator 1521b may be separated by the gap 123. The gap 123 may be configured to suppress heat transfer between the first evaporator 1521a and the second evaporator 1521b as shown in Figures 14 and 15, for example.

[0129] Each of the first evaporator 1521a and the second evaporator 1521b may comprise a top wall 1810, a bottom wall 1811 and a side wall 1812, the side wall 1812 connecting the top wall 1810 with the bottom wall 1811 as shown in Figure 13, for example.

[0130] The side wall 1812 of the first evaporator 1521a may be separated from the side wall 1812 of the second evaporator 1521b by the gap 123.

[0131] At least one of the top wall 1810, the bottom wall 1811 and the side wall 1812 may be covered by a porous structure 1820.

[0132] The porous structure 1820 on the bottom wall 1811 of the first and second evaporators 1521a, 1521b may comprise a porous fin structure 1830 with longitudinal fins extending from the side walls 1812 of the first and second evaporators 1521a, 1521b to the contact areas 122a, 122b, 126a, 126b of the heat spreaders 120a, 120b as shown in Figure 18, for example.

[0133] The porous structure 1820 may be absent near the one or more bridges 127a, 127b.

[0134] The porous structure 1820 near the one or more bridges 127a, 127b of the first vapor chamber 1520a may have a larger pore size than the porous structure 1820 near the one or more bridges 127a, 127b of the second vapor chamber 1520b as shown in Figure 14, for example. The porous structure 1820a near the one or more bridges 127a, 127b of the first vapor chamber 1520a may have a larger pore size than the porous structure 1820 in areas of the first vapor chamber 1520a adjacent thereto.

[0135] The porous structure 1820b near the one or more bridges 127a, 127b of the second vapor chamber 1520b may have a smaller pore size than the porous structure 1820 in areas of the second vapor chamber 1520b adjacent thereto as shown in Figure 14, for example.

[0136] Figure 1 also represents an embodiment of a cooling assembly 100 where the heat spreaders 120a, 120b comprise vapor chambers with respective evaporators. Such cooling assembly 100 comprises at least two vapor chambers (VC) 120a, 120b for spreading heat from at least two heat sources 110a, 110b, where: Evaporators (heat receiving zones) are located on the side (or comer) of each VC; and VCs are stacked to each other at least by the sides with corresponding evaporators with the gap 123. In other words, first evaporator is separated from second evaporator by the gap 123.

[0137] Figure 2 shows a schematic diagram illustrating top views on the cooling assembly 100 of Figure 1 with different examples for location and shape of contact areas.

[0138] Top left picture shows a cooling assembly 100 with first and second heat spreaders 120a, 120b which are separated by a gap 123.

[0139] The first heat spreader 120a comprises a first main surface 121a facing the first heat dissipation area 110a. A first contact area 122a is formed on a section of the first main surface 121a. The first contact area 122a is contacting the first heat dissipation area 110a as shown in Figure 1.

[0140] The second heat spreader 120b comprises a first main surface 121b facing the second heat dissipation area 110b. A first contact area 122b is formed on a section of the first main surface 121b. The first contact area 122b is contacting the second heat dissipation area 110b.

[0141] The first contact area 122a of the first heat spreader 120a is arranged at a side 123 a of the first heat spreader 120a facing the second heat spreader 120b. The first contact area 122b of the second heat spreader 120b is arranged at a side 123b of the second heat spreader 120b facing the first heat spreader 120a.

[0142] The first contact area 122a of the first heat spreader 120a is arranged at a middle section 124a of the side 123a of the first heat spreader 120a facing the second heat spreader 120b. The first contact area 122b of the second heat spreader 120b is arranged at a middle section 124b of the side 123b of the second heat spreader 120b facing the first heat spreader 120a.

[0143] The first contact area 122a of the first heat spreader 120a has an equal size as the first contact area 122b of the second heat spreader 120b.

[0144] In the bottom left picture of Figure 2, the first contact area 122a of the first heat spreader 120a is arranged at a comer section 125a of the side 123a of the first heat spreader 120a facing the second heat spreader 120b. The first contact area 122b of the second heat spreader 120b is arranged at a comer section 125b of the side 123b of the second heat spreader 120b facing the first heat spreader 120a. The first contact area 122a of the first heat spreader 120a has an equal size as the first contact area 122b of the second heat spreader 120b.

[0145] In the top right picture of Figure 2, four heat spreaders 120a, 120b, 120c, 120d are shown, each one having a respective heat dissipation area 110a, 110b, 110c, l lOd.

[0146] The contact areas 122a, 122b for each of the heat spreaders 120a, 120b, 120c, 120d are arranged at a comer section of the respective heat spreader.

[0147] In the bottom right picture of Figure 2, two heat spreaders are shown 120a, 120b. For each heat spreader 120a, 120b a number of contact areas 122a, 126a, 122b, 126b is greater than one, in this case equal to two.

[0148] The contact areas 122a, 126a, 122b, 126b for each of the heat spreaders 120a, 120b are arranged at a side 123a, 123b of the respective heat spreader 120a, 120b.

[0149] Figure 3 shows a schematic diagram illustrating top views on the cooling assembly 100 of Figure 1 with different examples for location and shape of contact areas.

[0150] Top picture shows a cooling assembly 100 with first and second heat spreaders 120a, 120b which are separated by a gap 123.

[0151] For each heat spreader 120a, 120b a number of contact areas 122a, 126a, 122b, 126b is greater than one, in this case equal to two.

[0152] The contact areas 122a, 122b are arranged at a side 123a, 123b of the respective heat spreader 120a, 120b and are different in size.

[0153] The contact areas 126a, 126b have about the same size as can be seen from Figure 3.

[0154] Bottom picture shows a cooling assembly 100 with first, second and third heat spreaders 120a, 120b, 120c which are separated by respective gaps.

[0155] First and third heat spreaders 120a, 120c each have a single contact area 110a, 1 lOd while second heat spreader 120b (in the middle) have two contact areas 110b, 110c which are different in size.

[0156] The contact areas 122a, 122b, 122c, 122d are arranged at a respective side of the heat spreaders 120a, 120b, 120c.

[0157] The contact areas 126a, 126b have about the same size as can be seen from Figure 3.

[0158] Figure 4 shows a schematic diagram illustrating two cross sections 410, 420 of the cooling assembly 100 of Figure 1 with supporting plate 401, the top picture shows cross section 410 of the chip area while the bottom picture shows cross section 420 outside chip area. The supporting plate 401 supports the first heat spreader 120a and the second heat spreader 120b. The supporting plate 401 comprises a hole 402 as shown in Figure 4. The first heat dissipation area 110a and the second heat dissipation area 110b are arranged inside the hole 402.

[0159] The hole 402 of the supporting plate 401 may be open to one side or two sides of the first heat spreader 120a and the second heat spreader 120b.

[0160] While Figure 4 shows a single hole 402 in the supporting plate 401, the supporting plate 401 may comprise a plurality of holes 402. Each hole 402 may be configured to accommodate one or more heat dissipation areas 110a, 110b of neighboring heat spreaders 120a, 120b which are separated by respective gaps 123.

[0161] A circumference of each hole 402 may be configured to surround contact areas contacting the respective one or more heat dissipation areas 110a, 110b of the neighboring heat spreaders 120a, 120b. The following Figures give examples for shape of supporting plate 401 and assembling with heat spreaders.

[0162] Figure 5 shows a top view 510 on an exemplary supporting plate 401, a top view 520 on an exemplary configuration of two heat spreaders and a top view 530 on a cooling assembly 100 with such supporting plate 401 and heat spreaders configuration.

[0163] The top left picture (A) shows supporting plate 401 with hole 402. The bottom picture (B) shows two heat spreaders 120a, 120b with first and second heat dissipation areas 110a, 110b.

[0164] The right-side picture (A+B) shows a combination of the supporting plate 401 (A) with the two heat spreaders (B). In the combination, the first and second heat dissipation areas 110a, 110b are placed inside the hole 402 of the supporting plate 401.

[0165] Figure 6 shows a top view 610 on an exemplary cooling assembly 100 with an exemplary shape of supporting plate 401 and configuration of heat spreaders.

[0166] In this cooling assembly, the hole 402 of the supporting plate 401 is open to one side of the second heat spreader 120b.

[0167] Figure 7 shows a top view 710 on an exemplary supporting plate 401, a top view 720 on an exemplary configuration of two heat spreaders and a top view 730 on a cooling assembly 100 with such supporting plate 401 and heat spreaders configuration.

[0168] The top left picture (A) shows supporting plate 401 with hole 402. The bottom picture (B) shows two heat spreaders 120a, 120b with first and second heat dissipation areas 110a, 110b.

[0169] The right-side picture (A+B) shows a combination of the supporting plate 401 (A) with the two heat spreaders (B). The supporting plate 401 is larger in size than the combined outline of the two heat spreaders 120a, 120b. In the combination, the hole 402 of supporting plate 401 is open at two sides of the first and second heat spreaders 120a, 120b.

[0170] Figure 8 shows a top view 810 on an exemplary cooling assembly 100 with an exemplary shape of supporting plate 401 and configuration of heat spreaders. In this exemplary configuration, the supporting plate 401 is smaller in size than the combined outline of the two heat spreaders 120a, 120b. In the combination (A+B), the hole 402 of supporting plate 401 has a closed contour.

[0171] Figure 9 shows a top view 910 on an exemplary cooling assembly 100 with an exemplary shape of supporting plate 401 and configuration of heat spreaders.

[0172] In this exemplary configuration, the supporting plate 401 is larger in size than the combined outline of the two heat spreaders 120a, 120b. In the combination (A+B), the hole 402 of supporting plate 401 is open at one side of the first and second heat spreaders 120a, 120b.

[0173] Figure 10 shows a top view 1010 on an exemplary cooling assembly 100 with an exemplary shape of supporting plate 401 and configuration of heat spreaders as well as exemplary fin 1001 and pin 1002 structures on the bridge area 403 of supporting plate.

[0174] In this exemplary configuration, the supporting plate 401 is larger in size than the combined outline of the two heat spreaders 120a, 120b. The hole 402 of supporting plate 401 has a closed contour.

[0175] The supporting plate 401 comprises a bridge section 403 that is arranged along the gap 123 between the first and second heat spreaders 120a, 120b outside the contact areas 122a, 122b, 126a, 126b of the heat spreaders 120a, 120b.

[0176] The bridge section 403 of the supporting plate 401 comprises a fin 1001 or pin 1002 structure attached to one or both sides of the supporting plate 401.

[0177] The fin or pin structure can touch the heat spreaders 120a, 120b. If they do not touch the heat spreaders, then heat leak is smallest. But if they touch the heat spreaders 120a, 120b, then mechanical stability can be improved. Even if pin / fin structure 1001, 1002 is touching the heat spreaders 120a, 120b, the contact thermal resistance is small, so both mechanical and thermal performance can be balanced.

[0178] Figure 11 shows top views 1110, 1120, 1130 on an exemplary cooling assembly 100 with exemplary configurations for bridge section.

[0179] In the left view 1110, bridge section 403 is extended to the first heat spreader 120a.

[0180] In the middle view 1120, bridge section 403 is extended to the second heat spreader 120b.

[0181] In the right-side view 1130, bridge section 403 is extended to both heat spreaders 120a, 120b.

[0182] The bridge section 403 can have different designs. For example, it can be made of several layers of material where internal layer on the bridge section 403 is absent or empty space on the bridge section 403 if filled by low thermal conductive material.

[0183] For example, a gap can be placed between the bridge section 403 of the supporting plate 401 and the first and second heat spreaders 120a, 120b. This gap can be configured to reduce heat transfer between the bridge section 403 and the heat spreaders 120a, 120b. The gap between bridge section 403 of supporting plate 401 and heat spreaders 120a, 120b is the gap (e.g., air gap or gas gap) with low thermal conductivity, so the heat transfer is reduced.

[0184] The bridge section 403 of the supporting plate 401 may comprise a layered material stack with an internal material layer being absent or being empty space or being filled by a low thermal conductivity material or being filled by a porous material.

[0185] The material of supporting plate 401 can be steel, aluminum, ceramics etc. Moreover, the supporting plate 401 can have other functions, for example, the supporting plate 401 can be part of the heat sink 130a, 130b, the supporting plate 401 can be a printed circuit board, the supporting plate 401 can be a case of an electronic device, etc.

[0186] In addition, the number of heat spreaders 120a, 120b (or VCs) and the number of heat sources, i.e., heat dissipation areas 110a, 110b to be cooled (and surrounded by hole 402 of supporting plate 401) can be more than two. For example, three or more heat spreaders 120a, 120b (or VCs) can be located on one supporting plate 401, and three or more heat dissipation areas 110a, 110b (or evaporators) can be located in one hole 402 of supporting plate 401 to cool three or more heat sources.

[0187] In one implementation, the design of bridge sections 403 or bridge areas, respectively can be just through holes.

[0188] Figure 12 shows a schematic diagram illustrating two cross sections of an exemplary cooling assembly 1200 comprising vapor chambers and exemplary supporting plate 401 having different structures 403, 404, the top picture shows cross section of the chip area while the bottom picture shows cross section outside chip area.

[0189] In the configuration of the cooling assembly 100, the first heat spreader 120a comprises a first vapor chamber 1520a for spreading heat from the first heat dissipation area 110a (also referred to as first heater) and the second heat spreader 120b comprises a second vapor chamber 1520b for spreading heat from the second heat dissipation area 110b (also referred to as second heater).

[0190] The first vapor chamber 1520a comprises a first evaporator 1521a placed above the first heat dissipation area 110a and the second vapor chamber 1520b comprises a second evaporator 1521b placed above the second heat dissipation area 110b.

[0191] The first evaporator 1521a and the second evaporator 1521b are separated by the gap 123. The gap 123 is configured to suppress heat transfer between the first evaporator 1521a and the second evaporator 1521b.

[0192] Both vapor chambers 1520a, 1520b are placed on a supporting plate 401. The structure of supporting plate 401 near the interface between the two vapor chambers 1520a, 1520b, i.e., at the bridge area 403, is different from the areas 404 outside the interface area 403 (modified areas), e.g., as shown in Figures 5 to 11.

[0193] According to a first option, the modified bridge area 403 can have different cross section. According to a second option, the modified bridge area 403 can have smaller thermal conductivity.

[0194] Figure 13 shows a top view of an exemplary evaporator 1300 of a vapor chamber of a cooling assembly 1200 according to the disclosure and two different cross sections of the evaporator in the bottom pictures. The figure illustrates an exemplary design of internal porous structure of VC, e.g. VCs 1520a, 1520b as shown in figure 12, i.e., for the scenario when spreading principle follows approach of vapor chamber. Figure 13 shows the design of evaporator, e.g., evaporators 1521a, 1521b as shown in figure 12, where evaporator has porous fins 130, extending from the side wall 1812 to the whole evaporator area.

[0195] Each of the first evaporator 1521a and the second evaporator 1521b may comprise a top wall 1810, a bottom wall 1811 and a side wall 1812 as shown in Figure 13. The side wall 1812 is connecting the top wall 1810 with the bottom wall 1811.

[0196] The side wall 1812 of the first evaporator 1521a can be separated from the side wall 1 12 of the second evaporator 1521b by the gap 123 (see Figure 14).

[0197] At least one of the top wall 1810, the bottom wall 1811 and the side wall 1812 may be covered by a porous structure 1820. In F igure 13 each one of top wall 1810, bottom wall 1811 and side wall 1812 is covered by a porous structure 1820.

[0198] The porous structure 1820 on the bottom wall 1811 of the first and second evaporators 1521a, 1521b may comprise a porous fin structure 1830 with longitudinal fins as shown in Figure 13. The fins are extending from the side walls 1812 of the first and second evaporators 1521a, 1521b to the contact areas 122a, 122b, 126a, 126b of the heat spreaders 120a, 120b.

[0199] Figure 14 shows a top view of an exemplary cooling assembly 1400 where two vapor chambers are connected directly by small bridges and three different cross sections of the cooling assembly 1200 in the bottom pictures.

[0200] The first and second VCs 1520a, 1520b can be connected directly to each other on several areas, and wick structure at these areas can be different compared to wick structure at the areas without connection as can be seen from Figure 14.

[0201] In the upper picture of Figure 14, two heat spreaders 120a, 120b or vapor chambers 1520a, 1520b are shown which are connected directly by small bridges 127a, 127b. So, two kinds of areas are present: A - area near VC bridge 127a, B - area outside the VC bridge 127b.

[0202] For A-area there are two possible options:

[0203] Option 1 : there is no wick near the bridges 127a, 127b to avoid intensive two-phase heat exchange (evaporation or condensation).

[0204] Option 2: near the bridge 127a, 127b hot VC 1520b has fine powder wick and cold VC 1520a has coarse powder wick. Fine powder wick on the hot VC 1520b side is flooded due to high capillary forces, and condensation HTC becomes small (condensation appears only on the surface of porous structure and no volumetric condensation inside the wick happens). Coarse powder wick on the cold VC 1520a side dries out due to low capillary forces, and evaporation HTC becomes small (no evaporation due to absent of liquid phase inside the wick).

[0205] At a distance from the bridges 127a, 127b (area B), the top and bottom wicks are connected by a layer of wick on the wall to ensure an effective supply of liquid near the evaporator. As can be seen from the bottom left picture of Figure 14, the porous structure 1820 can be absent near the one or more bridges 127a, 127b.

[0206] The porous structure 1820 near the one or more bridges 127a, 127b of the first vapor chamber 1520a can have a larger pore size than the porous structure 1820 near the one or more bridges 127a, 127b of the second vapor chamber 1520b.

[0207] Another feature is the following: The porous structure 1820a near the one or more bridges 127 a, 127b of the first vapor chamber 1520a can have a larger pore size than the porous structure 1820 in areas of the first vapor chamber 1520a adjacent thereto; and the porous structure 1820b near the one or more bridges 127a, 127b of the second vapor chamber 1520b can have a smaller pore size than the porous structure 1820 in areas of the second vapor chamber 1520b adjacent thereto.

[0208] Figure 15 shows a side view of an exemplary cooling assembly 1500 where the package or chip has a power map with nonregular heat dissipation and temperature requirements.

[0209] In this example, the evaporators 1521a, 1521b may cover different areas on one chip (or one electronic package 110). For example, the chip or package 110 may have a power map with non-regular heat dissipation and temperature requirements, and separated VCs 1520a, 1520b are aligned with the chip (or package 110) according to power map following one of possible criteria (or both of them):

[0210] 1) one VC (e.g., 1520b) covers high power region of map, and second VC (e.g., 1520a) covers low power region of map;

[0211] 2) one VC (e.g., 1520a) covers temperature sensitive region of map, and second VC (e.g., 1520b) covers less temperature sensitive region of map.

[0212] Figure 16 shows a 3D view, a cross section and a longitudinal section of an exemplary cooling assembly 1600 with two heat spreaders 120a, 120b and supporting plate 401. Figure 17 shows a 3D view, a cross section and a longitudinal section of the supporting plate 401 of the cooling assembly 1600 shown in Figure 16. The cooling assembly 1600 shown in Figures 16 and 17 is an exemplary implementation of the cooling assembly 100 described above.

[0213] The cooling assembly 1600 comprises a first head spreader 120a and a second head spreader 120b which are connected via bridges 127a, 127b within the gap 123. The first head spreader 120a has a cooling area with low temperature 1601 and the second head spreader 120b has a cooling area with high temperature 1602.

[0214] In the cross section of Figure 16, the second spreader 120b is shown in detail with the bridges 127a, 127b between spreaders and the bridge areas (or bridge sections 403) of supporting plate 401 with fins, 2ndheat source 110b and evaporator area 1302 of 2ndspreader.

[0215] In the longitudinal section of Figure 16, the first and second spreaders 120a, 120b are shown in detail with 1stand 2ndheat sources 110a, 110b and evaporator areas 1301, 1302 of 1stand 2ndspreaders.

[0216] In the cross section of Figure 17, the evaporator 1300 of second spreader 120b is shown and in the longitudinal section of Figure 17, the evaporator 1300 of first spreader 120a is shown. As already described above, the cooling assembly 1600 comprises at least two heat sources to be cooled - 1stheater and 2ndheater (also referred to as first heat dissipation area 110a and second heat dissipation area 110b). The 2ndheater 110b has larger heat dissipation power Q2, but can operate at high temperature T2 too. And the 1stheater 110a has smaller heat dissipation power QI < Q2, but has to operate at smaller temperature T1 < T2.

[0217] Then cooling assembly 1600 comprises at least two heat spreaders 120a, 120b having plate-like shape and they are stacked to each other on the side (with gap 123 to avoid heat transfer between each other). Then 1stheat spreader 120a is coupled thermally (soldered directly or connected through the thermal interface materials such as thermal grease) to the 1stheater 110a, and 2ndheat spreader 120b is coupled thermally to the 2ndheater 110b.

[0218] In one exemplary implementation as described in this disclosure, the heat spreader design can be mainly vapor chamber operated by the principle of flat heat pipe, where heat is spread due to internal capillary driven vapor-liquid circulation coupled by evaporation-condensation process. Therefore, the parts of spreaders connected to the heaters are called evaporators (for more general formulation, it can be called “heat receiving zones”). In most broad description, the spreader can be based on other physical principles. The key point is that spreader has highly efficient thermal conductivity and can transport heat on relatively long distance with low temperature difference.

[0219] Spreaders receive heat from the heaters and distribute (spread, transfer) it to the larger area - remaining part of spreader, which is coupled to heat sink. Heat sink can be air cooled fins or liquid cooled cold plate, where the coolant (air, cooling liquid etc.) receives heat from the heat spreader. The temperature of heat spreader is determined by the amount of transferred heat and temperature of coolant. So, in order to achieve the low temperature level on the 1stheater, the coolant with low temperature is supplied to the heat sink of 1stheat spreader coupled with 1stheater having low power. After coolant passes 1stheat sink, it has larger temperature compared to the inlet due to received heat and can be transferred to the 2ndheat sink - due to the fact that 2ndheat sink and spreader can operate at higher temperature (because 2ndheater can operate at high temperature reliably) coolant can have higher temperature on the inlet and cooling is performed reliably.

[0220] As described above with respect to Figure 1, thermo-coupling according to the first option (Optl, dotted line arrow) shown in Figure 1 can be applied where the coolant 141, 142 is an air flow which is led by the heat sink 130a, 130b for cooling the two sections 130a, 130b of the heat sink and thus the cooling assembly 100. Alternatively (or additionally), thermo-coupling according to the second option (Opt2, solid line arrow) shown in Figure 1 can be applied where the coolant 141, 142 is a liquid flow which is led, e.g., in a cooling channel, for liquid cooling the two sections 130a, 130b of the heat sink and thus the cooling assembly 100.

[0221] Due to this principle, temperature of 1stheater can be significantly smaller than temperature of 2ndheater due to separated cooling approach. In order to get maximum benefit of this cooling method, additional features are introduced:

[0222] First and second heat spreaders 120a, 120b are connected mechanically to each other by supporting plate 401, so the supporting plate 401 surrounds the stacked evaporators (supporting plate 401 has the hole 402 where evaporators are located), and on the area outside the hole 402, the supporting plate 401 has such modified structure near interface between two vapor chambers that heat transfer from one side of supporting plate 401 (coupled with second spreader) to another side of supporting plate (coupled with first spreader) is minimized.

[0223] When principle of operation of spreader is based on vapor chamber approach, then special wick structure can be used to: To ensure efficient liquid supplying to evaporation area, the evaporator can have porous fins extending from the side wall to the evaporation area (see Figures 13 and 18);

[0224] To avoid heat transfer on the bridged areas, the wick structure near bridge region can be arranged in such way that heat transfer coefficients are minimal. So, it avoids heat leaks between two vapor chambers.

[0225] Figure 18 shows a 3D view, a cross section and a plane section of an exemplary evaporator 1300 of a vapor chamber of a cooling assembly according to the disclosure.

[0226] The figure illustrates an exemplary design of internal porous structure of VC, e.g., vapor chamber design as shown in Figures 16 and 17 or VCs 1520a, 1520b as shown in Figure 12, i.e., for the scenario when spreading principle follows approach of vapor chamber.

[0227] Figure 18 shows the design of evaporator 1300, e.g., evaporator 1300 shown in Figure 13 or evaporators 1521a, 1521b as shown in Figure 12, where evaporator has porous fins 1830, extending from the side wall 1812 to the whole evaporator area.

[0228] The evaporator 1300 may comprise a top wall 1810, a bottom wall 1811 and a side wall 1812 as shown in Figure 18. The side wall 1812 is connecting the top wall 1810 with the bottom wall 1811.

[0229] At least one of the top wall 1810, the bottom wall 1811 and the side wall 1812 may be covered by a porous structure 1820. In Figure 18 each one of top wall 1810, bottom wall 1811 and side wall 1812 is covered by a porous structure 1820.

[0230] The porous structure 1820 may comprise a porous fin structure 1830 with longitudinal fins as shown in Figure 18. The fins are extending from the side wall 1812 of the evaporator 1300 to the contact areas (not shown) of the heat spreader.

[0231] For tests, a sample of cooling assembly with vapor chamber as shown in Figures 16 to 18 was fabricated, which includes features from Figures 1 to 15. In this implementation, cooling assembly has two VCs stacked together, evaporators are located on the stacked area, and evaporators are connected to the heat sources with significantly different heat dissipation. In addition, two VCs were coupled both by steel supporting plate with grooves on the bridge area, and also VCs are connected by small VC bridges directly to each other, and no wicks were arranged on the VC bridge area.

[0232] The following table illustrates the results when testing the above-described samples, where each line corresponds to different heating power: In the above table, temperatures on the area “1stbase” are temperatures of evaporator wall of cold VC used for cooling of low power heat source with low required temperature, and temperatures on the area “2ndbase” are temperatures of evaporator wall of hot VC used for cooling of high-power heat source with high required temperature. It can be seen from the table, that temperatures on 1stbase are at least smaller by ~30 degrees compared to temperatures on 2ndbase, so a significant temperature difference between two heat sources can be achieved.

[0233] Instead of vapor chamber, other kinds of thermal spreaders can be used: For example, just plates of solid materials with high thermal conductivity such as copper, diamond, graphite, graphen, high conductive composite materials etc. Another fluidic spreader can be used such as heat pipes, thermosiphons, loop heat pipes, evaporators of 1 -phase or 2-phase pumped loops, cold plates, evaporators of vapor refrigeration units etc.

[0234] Staking of spreaders can be arranged not in-plane (horizontally), but at different height levels or vertically.

[0235] Heat source to be cooled by this method can be an electronic package, a chip, or any other device such as electric batteries, optical devices and other process equipment where localized heat dissipation appear and highly non-regular cooling is required.

[0236] The features of the cooling assembly shown in Figures 16 to 18 can be described as follows: A cooling assembly 1600, having at least two vapor chambers (two heat spreaders 120a, 120b), for spreading heat from at least two heat sources 110a, 110b, where evaporators 1300 are located on the side (or comer) of each VC, and VC are stacked to each other at least by the sides with corresponding evaporators with the gap, (in other words, first evaporator is separated from second evaporator with the gap).

[0237] Different numbers of evaporators, different number of spreaders, different location of evaporators etc. can be implemented.

[0238] The cooling assembly 1600 can have a supporting plate 401. The supporting plate can have a hole 402, and two (or more) evaporators 1300 can be located inside the hole 402.

[0239] A structure of the supporting plate 401 near an interface between the two vapor chambers (bridge area 403) can be different (modified) compared to a structure in the areas outside the bridge: 1) fins (or pins) 1830 can be extending in the different directions; 2) internal cavities; 3) through holes with size smaller than main hole; 4) structure of bridge area extending at least to the part of area outside bridge.

[0240] A material of the supporting plate 401 can be steel, aluminum, ceramics etc.

[0241] The supporting plate 401 can have other functions: (Option 1) supporting plate 401 can be the part of heat sink; (Option 2) supporting plate 401 can be printed circuit board; (Option 3) supporting plate can be case of electronic device.

[0242] One VC can have several evaporators 1300, and one supporting plate 401 can have several holes 402, so each hole (or at least one) surround two or more evaporators 1300.

[0243] Fins or pins of supporting plate 401 can touch VC.

[0244] On the bridge area 403 there can be a gap between VC and supporting plate 401. At the evaporator 1300 portion of VC, the side wall 1812 can consist of wick, and porous fins extending from the side wall 1812 to the evaporation area along VC plane to improve liquid supply to the evaporation zone.

[0245] Two VCs can be connected by bridges 127a, 127b, and walls near the bridges don’t have wick to avoid two-phase heat transfer, and walls outside bridges have the wick to ensure liquid reflow from top to the bottom; walls near the bridges have fine wick on the side of hot VC and coarse wick on the side of cold VC to suppress condensation and evaporation heat transfer correspondingly with following reduction of heat leakage rate.

[0246] First and second heat sources 110a, 110b can be the part of one chip or one package.

[0247] Evaporators 1300 can cover different areas on one chip (or package), and chip has power map, and: one VC can cover high power region of map, and second VC can cover low power region of map. One VC can cover temperature sensitive region of map, and second VC can cover less temperature sensitive region of map.

[0248] The disclosure also relates to a method for producing a cooling assembly 100, e.g., as described above with respect to Figures 1 to 18, for cooling an electronic package with a first heat dissipation area and a second heat dissipation area.

[0249] Such a method comprises: providing an electronic package with a first heat dissipation area and a second heat dissipation area, wherein a heat dissipation measure of the first heat dissipation area is lower than a heat dissipation measure of the second heat dissipation area; placing a first heat spreader above the first heat dissipation area; placing a second heat spreader above the second heat dissipation area; and placing a heat sink on the first heat spreader and the second heat spreader, the heat sink dissipating heat received via the first and second heat spreaders from the first and second heat dissipation areas of the electronic package; wherein the first heat spreader and the second heat spreader are separated by a gap to reduce heat transfer between the first heat spreader and the second heat spreader.

[0250] While a particular feature or aspect of the disclosure may have been disclosed with respect to only one of several implementations, such feature or aspect may be combined with one or more other features or aspects of the other implementations as may be desired and advantageous for any given or particular application. Furthermore, to the extent that the terms "include", "have", "with", or other variants thereof are used in either the detailed description or the claims, such terms are intended to be inclusive in a manner similar to the term "comprise". Also, the terms "exemplary", "for example" and "e.g." are merely meant as an example, rather than the best or optimal. The terms “coupled” and “connected”, along with derivatives may have been used. It should be understood that these terms may have been used to indicate that two elements cooperate or interact with each other regardless whether they are in direct physical or electrical contact, or they are not in direct contact with each other.

[0251] Although specific aspects have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and / or equivalent implementations may be substituted for the specific aspects shown and described without departing from the scope of the disclosure. This application is intended to cover any adaptations or variations of the specific aspects discussed herein.

[0252] Although the elements in the following claims are recited in a particular sequence with corresponding labeling, unless the claim recitations otherwise imply a particular sequence for implementing some or all of those elements, those elements are not necessarily intended to be limited to being implemented in that particular sequence. Many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the above teachings. Of course, those skilled in the art readily recognize that there are numerous applications of the disclosure beyond those described herein. While the disclosure has been described with reference to one or more particular embodiments, those skilled in the art recognize that many changes may be made thereto without departing from the scope of the disclosure. It is therefore to be understood that within the scope of the appended claims and their equivalents, the disclosure may be practiced otherwise than as specifically described herein.

Claims

CLAIMS:

1. A cooling assembly (100), comprising: an electronic package (110) with a first heat dissipation area (110a) and a second heat dissipation area (110b), wherein a heat dissipation measure of the first heat dissipation area (110a) is lower than a heat dissipation measure of the second heat dissipation area (110b); a first heat spreader (120a) placed above the first heat dissipation area (110a); a second heat spreader (120b) placed above the second heat dissipation area (110b); and a heat sink (130a, 130b) placed on the first heat spreader (120a) and the second heat spreader (120b), the heat sink (130a, 130b) being configured to dissipate heat received via the first and second heat spreaders (120a, 120b) from the first and second heat dissipation areas (110a, 110b) of the electronic package (110); wherein the first heat spreader (120a) and the second heat spreader (120b) are separated by a gap (123), the gap (123) being configured to reduce heat transfer between the first heat spreader (120a) and the second heat spreader (120b).

2. The cooling assembly (100) of claim 1, wherein the first heat spreader (120a) is configured for a lower temperature than the second heat spreader (120b).

3. The cooling assembly (100) of claim 2, wherein the first heat spreader (120a) comprises a first main surface (121a) facing the first heat dissipation area (110a); wherein a first contact area (122a) is formed on a section of the first main surface (121a), the first contact area (122a) contacting the first heat dissipation area (110a); and wherein the second heat spreader (120b) comprises a first main surface (121b) facing the second heat dissipation area (110b); wherein a first contact area (122b) is formed on a section of the first main surface (121b), the first contact area (122b) contacting the second heat dissipation area (110b).

4. The cooling assembly (100) of claim 3, wherein the first contact area (122a) of the first heat spreader (120a) is arranged at a side (123a) of the first heat spreader (120a) facing the second heat spreader (120b); and wherein the first contact area (122b) of the second heat spreader (120b) is arranged at a side (123b) of the second heat spreader (120b) facing the first heat spreader (120a).

5. The cooling assembly (100) of claim 4, wherein the first contact area (122a) of the first heat spreader (120a) is arranged at a middle section (124a) or at a comer section (125a) of the side (123a) of the first heat spreader (120a) facing the second heat spreader (120b); and wherein the first contact area (122b) of the second heat spreader (120b) is arranged at a middle section (124b) or at a comer section (125b) of the side (123b) of the second heat spreader (120b) facing the first heat spreader (120a).

6. The cooling assembly (100) of any of claims 3 to 5,wherein for each of the heat spreaders (120a, 120b) a number of contact areas (122a, 126a, 122b, 126b) is greater than one; and / or wherein the contact areas (122a, 126a, 122b, 126b) for each of the heat spreaders (120a, 120b) are arranged at a side (123a, 123b) or at a comer section (125a, 125b) of the respective heat spreader (120a, 120b).

7. The cooling assembly (100) of any of claims 3 to 6, wherein the heat sink (130a, 130b) comprises a first section (130a) and a second section (130b) which are separated from each other by the same gap (123) or another gap.

8. The cooling assembly (100) of claim 7, configured to use a coolant for cooling the cooling assembly (100); wherein the coolant enters firstly the first section (130a) of the heat sink and then enters the second section (130b) of the heat sink; and / or wherein the coolant entering the first section (130a) of the heat sink has a temperature smaller than a temperature of the coolant entering the second section (130b) of the heat sink.

9. The cooling assembly (100) of any of claims 3 to 8, comprising: a supporting plate (401) supporting the first heat spreader (120a) and the second heat spreader (120b), wherein the supporting plate (401) comprises a hole (402); wherein the first heat dissipation area (110a) and the second heat dissipation area (110b) are arranged inside the hole (402).

10. The cooling assembly (100) of claim 9, wherein the hole (402) of the supporting plate (401) is open to one side or two sides of the first heat spreader (120a) and the second heat spreader (120b).

11. The cooling assembly ( 100) of claim 9 or 10, wherein the supporting plate (401) comprises a plurality of holes (402), wherein each hole (402) is configured to accommodate one or more heat dissipation areas (110a, 110b) of neighboring heat spreaders (120a, 120b) which are separated by respective gaps (123).

12. The cooling assembly (100) of claim 11, wherein a circumference of each hole (402) is configured to surround contact areas (122a, 126a, 122b, 126b) contacting the respective one or more heat dissipation areas (110a, 110b) of the neighboring heat spreaders (120a, 120b).

13. The cooling assembly (100) of any of claims 9 to 12, comprising: one or more bridges (127a, 127b) within the gap (1 3), the one or more bridges (127a, 127b) being configured to mechanically connect the first heat spreader (120a) with the second heat spreader (120b).

14. The cooling assembly (100) of claim 13, wherein the one or more bridges (127a, 127b) between the first heat spreader (120a) and the second heat spreader (120b) are arranged within the gap (123) outside a common outline of the first heat dissipation area (110a) and the second dissipation area (100b).

15. The cooling assembly (100) of claim 13 or 14, wherein the supporting plate (401) comprises a bridge section (403) that is arranged along the gap (123) between the first and second heat spreaders (120a, 120b) outside the contact areas (122a, 122b, 126a, 126b) of the heat spreaders (120a, 120b).

16. The cooling assembly (100) of claim 15, wherein the bridge section (403) of the supporting plate (401) comprises a fin (1001) or pin (1002) structure attached to one or both sides of the supporting plate (401).

17. The cooling assembly (100) of claim 15 or 16, comprising: a gap between the bridge section (403) of the supporting plate (401) and the first and second heat spreaders (120a, 120b), the gap being configured to reduce heat transfer between the bridge section (403) and the heat spreaders (120a, 120b).

18. The cooling assembly (100) of any of claims 15 to 17, wherein the bridge section (403) of the supporting plate (401) comprises a layered material stack with an internal material layer being absent or being empty space or being filled by a low thermal conductivity material or being filled by a porous material.

19. The cooling assembly (100) of any of claims 15 to 18, wherein the bridge section (403) of the supporting plate (401) is extended to the first heat spreader (120a) or to the second head spreader (120b) or to both, the first and the second head spreaders (120a, 120b).

20. The cooling assembly (100) of any of claims 13 to 19, wherein the first heat spreader (120a) comprises a first vapor chamber (1520a) for spreading heat from the first heat dissipation area (110a) and the second heat spreader ( 120b) comprises a second vapor chamber (1520b) for spreading heat from the second heat dissipation area (110b); wherein the first vapor chamber (1520a) comprises a first evaporator (1521a) placed above the first heat dissipation area (110a) and the second vapor chamber (1520b) comprises a second evaporator (1521b) placed above the second heat dissipation area (110b); wherein the first evaporator (1521a) and the second evaporator (1521b) are separated by the gap (123), the gap (123) being configured to suppress heat transfer between the first evaporator (1521a) and the second evaporator (1521b).

21. The cooling assembly (100) of claim 20, wherein each of the first evaporator (1521a) and the second evaporator (1521b) comprises a top wall (1810), a bottom wall (1811) and a side wall (1812), the side wall (1812) connecting the top wall ( 1810) with the bottom wall ( 1811 );wherein the side wall ( 1812) of the first evaporator ( 1521 a) is separated from the side wall ( 1812) of the second evaporator (1521b) by the gap (123); wherein at least one of the top wall ( 1810), the bottom wall (1811) and the side wall ( 1812) are covered by a porous structure (1820); wherein the porous structure (1820) on the bottom wall (1811) of the first and second evaporators (1521a, 1521b) comprises a porous fin structure (1830) with longitudinal fins extending from the side walls ( 1812) of the first and second evaporators (1521a, 1521b) to the contact areas (122a, 122b, 126a, 126b) of the heat spreaders (120a, 120b).

22. The cooling assembly (100) of claim 21, wherein the porous structure (1820) is absent near the one or more bridges (127a, 127b).

23. The cooling assembly ( 100) of claim 21 , wherein the porous structure (1820) near the one or more bridges (127a, 127b) of the first vapor chamber (1520a) has a larger pore size than the porous structure (1820) near the one or more bridges (127a, 127b) of the second vapor chamber (1520b).

24. The cooling assembly (100) of claim 21, wherein the porous structure (1820a) near the one or more bridges (127a, 127b) of the first vapor chamber (1520a) has a larger pore size than the porous structure (1820) in areas of the first vapor chamber (1520a) adjacent thereto; and wherein the porous structure (1820b) near the one or more bridges (127a, 127b) of the second vapor chamber (1520b) has a smaller pore size than the porous structure (1820) in areas of the second vapor chamber (1520b) adjacent thereto.

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