CN110006282B - thermal ground plane - Google Patents

Abstract

The application relates to the field of heat exchange and discloses a thermal ground plane. For example, thermal ground planes have vapor cores of variable thickness. The thermal ground plane includes a first enclosure and a second enclosure, wherein the second enclosure and the first enclosure are configured to enclose a working fluid. The thermal ground plane further includes an evaporator region disposed at least partially on at least one of the first enclosure and the second enclosure, a condenser region disposed at least partially on at least one of the first enclosure and the second enclosure, and a wicking structure disposed between the first enclosure and the second enclosure. The vapor core is at least partially defined by a gap between the first shell and the second shell, the gap having a thickness that is variable between the first shell and the second shell.

Description

thermal ground plane

technical field

The present application relates to the field of heat exchange, and in particular, to a thermal ground plane.

Background technique

Thermal ground planes are often used in devices that require tight spaces with very thin thermal ground planes, such as mobile electronics. Also, for many thermal ground planes, thermal conductivity can be related to the thickness of the vapor core. For example, in the case of 45°C steam, when the gap is reduced from 200 μm to 100 μm, the effective thermal conductivity of the thermal ground plane can be reduced from 30,000 W/mK to 7,000 W/mK. When the gap is reduced from 100 μm to 50 μm, the effective thermal conductivity of the thermal ground plane can be further reduced, for example, from 7000 to 2000 W/mK. For example, a gap change of 50 μm or 100 μm can cause significant changes in the thermal properties of vapor transport. The thickness of the hot floor may create other thermal problems. A challenge in the prior art is to produce thermal ground planes that can be used in confined spaces with thin thicknesses and still provide efficient thermal performance.

SUMMARY OF THE INVENTION

Some embodiments of the present application provide a thermal ground plane, so that the steam core in the thermal ground plane has a variable thickness, so that the steam transport of the thermal ground plane can be optimized.

In order to solve the above technical problem, some embodiments of the present application provide a thermal ground plane including a first casing and a second casing, wherein the second casing and the first casing are configured to enclose a working fluid. The thermal ground plane may further include an evaporator zone disposed at least partially on at least one of the first and second casings, at least partially disposed on at least one of the first and second casings the condenser area, and a wicking structure disposed between the first shell and the second shell. A vapor core is at least partially defined by a gap between the first shell and the second shell, the thickness of which can vary between the first shell and the second shell, the vapor core is used in the evaporator region and the condensation Steam transfer between reactor zones.

In some embodiments, the gap may be designed to provide space for the expansion of the core gap.

In some embodiments, the thickness of the gap adjacent to the evaporator zone is less than the average gap thickness.

In some embodiments, the thickness of the gaps not adjacent to the evaporator zone is greater than the average gap thickness.

In some embodiments, either or both of the first shell and the second shell include a material that stretches and/or shrinks to expand the gap.

In some embodiments, the thermal ground plane may include a plurality of spacers disposed within the gap.

In some embodiments, the wicking structure may be in contact with either or both of the first shell layer and/or the second shell.

In some embodiments, the thermal ground plane may include additional wicking structures in contact with the wicking structures and the evaporator zone.

In some embodiments, the plurality of spacers may comprise copper or polymer encapsulated by a hermetic seal.

In some embodiments, the plurality of spacers may comprise springs.

In some embodiments, the plurality of spacers may comprise an elastic material.

In some embodiments, the thickness of the gap may be less than 50 μm.

In some embodiments, the gap may be defined by an internal pressure greater than ambient pressure.

The exemplary embodiments in the present application are not used to define or define the present application, but to provide assistance in understanding the present application. Other embodiments are discussed in the detailed description below. The beneficial effects of one or more embodiments can be further understood by reading the specification or implementing one or more embodiments.

Description of drawings

The features, details and effects of the present application can be better understood with reference to the specific embodiments and the corresponding drawings. One or more embodiments of the present application are exemplified by the pictures in the corresponding drawings, and these exemplary descriptions do not constitute limitations on the embodiments, and elements with the same reference numerals in the drawings are denoted as similar Elements, unless otherwise stated, the figures in the accompanying drawings do not constitute a scale limitation.

1 is a schematic diagram of a thermal ground plane according to some embodiments provided by way of example herein;

2 is a graph of the effective thermal conductivity of steam delivery for a thin 0.25 mm thermal ground plane according to some embodiments provided by way of example herein;

3 is a side view thermal ground plane of a thermal ground plane including a vapor core of variable thickness in accordance with some embodiments provided by way of example herein;

4A, 4B, 5A, and 5B are schematic diagrams of steps for fabricating a thermal ground plane with a variable thickness steam core according to some embodiments provided by way of example herein;

6A and 6B are schematic diagrams of a thermal ground plane with an extended thickness and/or a lower height of a first portion of a plurality of spacers in some embodiments provided by way of example in accordance with the present application;

7A and 7B are schematic diagrams of thermal ground planes of a first portion of a plurality of spacers having an expanded thickness and/or lower height and a corrugated or extruded profile in some embodiments provided by way of example in accordance with the present application;

8 is a schematic diagram of a thermal ground plane according to some embodiments provided by way of example herein;

Figures 9A, 9B, 10A and 10B are schematic diagrams of steps for fabricating a thermal ground plane with a variable thickness steam core according to some embodiments provided by way of example herein;

11 is a schematic diagram of a thermal ground plane that may include additional wicking structures disposed within a vapor core in some embodiments provided by way of example herein, wherein the thermal ground plane may be placed on circuit elements (eg, comparable to other circuit elements) wicking structures in regions near circuit components that produce more heat;

12 is a schematic diagram of a thermal ground plane in some embodiments provided by way of example in accordance with the present application with a first housing having a variable height that can accommodate the contours of the device housing. In some embodiments, voids associated with the device housing may be utilized to enhance vapor delivery;

13 is a schematic diagram of a thermal ground plane having a variable height first housing and a variable height second housing in accordance with some embodiments provided by way of example herein; and

14 is a schematic diagram of a thermal ground plane with a first housing of variable height and a second housing of variable height in accordance with some embodiments provided by way of example herein.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, each embodiment of the present invention will be described in detail below with reference to the accompanying drawings. However, those of ordinary skill in the art can appreciate that, in the various embodiments of the present invention, many technical details are set forth in order for the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can be realized.

The present application discloses a thermal ground plane including a variable thickness steam core. In some embodiments, the vapor core thickness may correspond to the three-dimensional shape of the circuit element and/or the device housing in which the thermal ground plane may be placed. The present application also discloses a method for fabricating a thermal ground plane with a variable thickness steam core.

FIG. 1 is a schematic diagram of an exemplary thermal ground plane 100 in accordance with some embodiments. The thermal ground plane 100 includes a first shell 105 and a second shell 110 that are sealed together to enclose the vapor core 115 and/or the wicking structure 120 . The first housing 105 and the second housing 110 may also enclose the working fluid in a vapor core and/or a wicking structure. Thermal ground plane 100 may be disposed near heat source 130 and/or heat sink 140 . The area of the thermal ground plane 100 near the heat source 130 may be the evaporator area 135 and/or the area of the thermal ground plane 100 near the heat sink 140 may be the condenser area 145 . For example, the working fluid may evaporate from the heat generated by the heat source 130 at or near the evaporator region 135 and/or the vapor may condense near the radiator 140 or condenser region 145 where the heat is lacking. Steam may flow from evaporator region 135 to condenser region 145 via steam core 115 . The working fluid may flow from the condenser region 145 to the evaporator region 135 through the wicking structure 120 .

In some embodiments, the wicking structure 120 may be deposited on either or both of the first shell 105 and the second shell 110 . In some embodiments, the thermal ground plane (eg, of which wicking structure 120 is a part) may include multiple microstructures. Microstructures may include, for example, a plurality of nanowires deposited on a plurality of micropillars, an array of nanowires, or a plurality of capped micropillars, and the like. In some embodiments, the wicking structure 120 may be understood as a wicking layer or a wicking structure layer.

In some embodiments, the working fluid may include water or any other coolant, which may transfer heat from the evaporator region 135 to the condenser region 145, eg, by one or more of the following mechanisms: a) Evaporation of the working fluid by absorption from heat dissipated by heat source 130 to form vapor; b) evaporative transport of the working fluid from evaporator region 135 to condenser region 145; c) cooling provided by radiator 145, condensing the vapor into a liquid; and/or d) passing through the wick The capillary pumping pressure created by the suction structure 120 returns the liquid from the condenser region 145 to the evaporator region 135 .

In some embodiments, the thermal performance of the thermal ground plane may depend on the configuration, but may be about 3-50 times that of copper.

In some embodiments, the first shell 105 and/or the second shell 110 and/or the wicking structure 120 may comprise copper, stainless steel, silicon, polymers, copper clad polyimide (Kapton) and/or or flexible materials, etc.

In some embodiments, the operation of the thermal ground plane is associated with a number of thermal resistances. For example, thermal resistances may include: a) thermal resistance in the evaporator region through a thermal ground plane shell (Re, shell); b) thermal resistance through an aqueous wicking structure (eg, copper wire mesh) in the evaporator region (Re, wire mesh); c) the thermal resistance (Ra, steam) for transporting steam from the evaporator to the condenser through the steam wick; d) the thermal resistance (Rc, wire mesh) through the water wicking structure in the condenser; e) the thermal resistance of the shell through the thermal ground plane within the condenser zone (Rc, shell); f) the thermal resistance of heat conduction from the condenser to the evaporator along the aqueous wicking structure (Ra, wire mesh); and/or g) Heat conduction thermal resistance from condenser to evaporator along the casing (Ra, casing).

For thick thermal ground planes (eg, thicknesses greater than or equal to about 1 mm), the gap (or height) of the core is large/high. Thus, steam can be transported through the steam core with little flow resistance and/or gas phase conduction thermal resistance (Ra, steam) is negligible. However, for thin thermal ground planes (eg, less than about 1 mm thick or between 0.25 mm and 0.35 mm thick), the gap (or height) of the core is significantly reduced. In some cases, vapor phase conduction thermal resistance (Ra, steam) may play a major role. The overall thermal performance of such a thin thermal ground plane may depend on the vapor phase conduction performance.

For example, the thermal performance of gas phase conduction can be represented by the effective thermal conductivity of gas phase conduction. As shown in FIG. 2, the effective thermal conductivity K _vapor of this gas phase conduction may be affected by the gap δv of the vapor core and/or the vapor temperature T. For example, when the gap δv is reduced from 200um to 100um, the effective thermal conductivity K _vapor of steam with a temperature T of 45°C can be reduced from 30000W/mK to 7000W/mK. For example, when the gap δv is reduced from 100um to 50um, the effective thermal conductivity can be further reduced from 7000W/mK to 2000W/mK. For example, changing the gap between 50um and 100um can result in significant changes in the thermal properties of gas phase conduction.

The thickness of mobile systems such as smartphones, tablets, watches, wearables, laptops and/or wearable electronics is very important. During the design phase, careful consideration must be given to reserving 50um or 100um of space for each device. Some embodiments of the present invention may incorporate a thermal ground plane with variable core thickness. In some embodiments, the variable thickness of the thermal ground plane can be matched to the clearance of the mobile system.

Air gaps are present on almost any smartphone, tablet, laptop or wearable electronic device. In some embodiments, such voids can be used to provide a thicker vapor core for the thermal ground plane, which can be used to improve gas phase conduction.

Components of different heights form multiple voids on circuit boards of mobile devices. Such voids can be used to improve vapor conduction in the thermal ground plane, dissipating the heat from the chip to the phone case. Similar gaps exist in other areas within the mobile system.

Additionally, the mobile device has variable spacing on the housing. In some embodiments, voids on the housing may also be used to optimize vapor phase conduction to the thermal ground plane.

A typical thermal ground plane is shown in Figure 1, which is flat. In this flat-plate configuration, the core can be designed for optimum performance. In some embodiments, the vapor core and other material layers of the thermal ground plane may vary, and available voids may be used. In most cases, with thin thermal ground planes, the temperature difference from one side of the thickness to the other is small. Therefore, directly attaching the wicking structure to the heat-generating chip may have little effect on the wicking structure. Not attaching the wicking structure to the chip allows for easier manufacture of the different vapor cores and their associated housings.

Steam cores with different gaps can be made by stamping or other forming processes. And this different gap can also be created by pressurizing the steam core and deforming the casing against the circuit board. In this embodiment, the housing may be a flexible material and/or plastic. After the molding process, the shell of the thermal ground plane can be strengthened.

As shown in Figure 2, adding 50um or 100um to the vapor core can effectively enhance the gas phase conduction in the thermal ground plane. The figure also shows that gas phase conduction is strongly influenced by steam temperature. Therefore, the enhancement effect has a significant effect on the part far from the heat generating chip. In these parts, the steam temperature is lower, resulting in poor gas phase conduction. These fractions refer to the fractions that can benefit from any enhancement.

FIG. 3 is a side view of a thermal ground plane 500 including a variable thickness steam core 520 in accordance with some embodiments. In some embodiments, the thermal ground plane 500 includes a first housing 510 (eg, a first housing) and a second housing 535 (eg, a second housing). The first housing 510 and the second housing 535 may be sealed together to encapsulate other elements of the thermal ground plane 500 . Thermal ground plane 500 may further include wicking structure 515 and vapor core 520 . The wicking structure 515 may be coupled, attached, contacted and disposed on the first housing 510 . In some embodiments, the wicking structure 515 may be made of copper, stainless steel, titanium, ceramics, or polymers. In some embodiments, if desired, the wicking structure may include or be coated with additional layers to prevent it from reacting with fluids.

In some embodiments, thermal ground plane 500 may be disposed between circuit board 530 with circuit elements 525 and 540 and device housing 505 . In this example, the height of circuit board 530 with circuit elements 525 and 540 is variable. The second housing 535 has a variable shape to accommodate the variable shape circuit board 530 and circuit elements 525 and 540 (eg, processors, memories, integrated circuits, etc.). The variable shape of the second shell 535 may form the vapor core 530 having a variable thickness. As shown, the thickness of the steam core 530 can vary whether the steam core 520 is adjacent to the circuit element 525 or the circuit element 540 .

In some embodiments, a variable width vapor core may enhance vapor conduction within the thermal ground plane 500 .

In some embodiments, an evaporator region may be formed near circuit elements 525 or 540 . In some embodiments, the evaporator region may not be formed near circuit elements 525 or 540 .

As shown in FIG. 3, the vapor core 520 is thicker at the portion of the thermal ground plane corresponding to the circuit board clearance. In some embodiments, the thickness of different portions of the vapor core may be different. In some embodiments, the second housing 535 of the thermal ground plane 500 may have a contoured shape, a three-dimensional shape, a varying shape, a non-planar shape, and the like. In some embodiments, the wicking structure 515 and/or the first housing 510 of the thermal ground plane 500 may be substantially flat. In some embodiments, both the first housing 510 and the second housing 535 of the thermal ground plane 500 may have contoured shapes, three-dimensional shapes, varying shapes, non-planar shapes, and the like.

In some embodiments, the evaporator zone may be disposed at least partially on the first housing 510 and/or the second housing 535 . For example, the evaporator region can be designed within the first housing 510 and/or the second housing 535 so that, in use, it is located near a heat source, such as one or more circuit elements 525 and 540 .

In some embodiments, a condenser zone may be disposed at least partially on first housing 510 and/or second housing 535 . For example, the condenser zone may be designed within the first housing 510 and/or the second housing 535 so that, in use, it is located near a region that is cooler than the heat source.

The steam core 520 includes 2 thinner steam core regions 520A and 520B, and 3 thicker steam core regions 520C, 520D and 520E. In some embodiments, the thickness of the steam core regions 520A and 520B is less than the average thickness of the steam core. In some embodiments, the thickness of the steam core regions 520C, 520D and 520E is greater than the average thickness of the steam core. In some embodiments, the thickness of one or more of the vapor core regions 520A and 520B is less than about 50 μm to 100 μm. In some embodiments, the thickness of one or more of the vapor core regions 520C, 520D, and 520E is greater than about 50 μm to 100 μm.

4A, 4B, 5A, and 5B illustrate the steps of making a thermal ground plane with a variable thickness steam core in accordance with some embodiments. For example, in FIG. 4A , a plurality of spacers 615 may be provided or fabricated on the second housing 535 . The plurality of spacers 615 may be disposed on the second casing 535 by means of electroplating, metal etching, polymer deposition, photolithography, and vapor deposition. In some embodiments, the plurality of spacers may be hermetically sealed or coated with a corrosion resistant coating.

For example, in FIGS. 4B and 5A , the second housing 535 and the plurality of spacers 615 may be pressed against the molded base plate 605 , eg, using the molded top plate 610 . For example, molding substrate 605 may have a three-dimensional form, shape, or model of circuit board 530 of circuit elements 525 and 540 . In some embodiments, the shape of the molding substrate 605 may be defined by a circuit board void.

FIG. 5B shows a thermal ground plane 600 with a permanently deformed second housing 535 and a plurality of spacers 615 integrated with other layers. In this example, the wicking structure 515 is in contact with, coupled to, disposed on, grown on the first shell 510 . In this example, the first housing 510 may be flat. In this example, the thermal ground plane 600 includes a vapor core having a variable thickness. In some embodiments, the gas within the thermal ground plane 600 may be vented before the water or other cooling liquid fills the thermal ground plane 600 . Various other steps may include: sealing the first housing 510 and the second housing 535 together; filling the thermal ground plane 600; applying one or more coatings to the thermal ground plane 600, and the like. In some embodiments, during normal operation, the water vapor pressure within the thermal ground plane 600 may be below atmospheric pressure. For example, lower pressures may cause one or both of the shell and/or other layers of the thermal ground plane to be pulled in the opposite direction to the spacers used to define the vapor core. In some embodiments, each forming step of the thermal ground plane 600 may be accomplished through the forming step using a set of fixtures. In some embodiments, the various forming steps of the thermal ground plane 600 may be accomplished by a roll-to-roll forming process.

Various other techniques may be used to form the height of the plurality of spacers 615 . For example, some of the plurality of spacers 615 may be etched away using photolithographic techniques. In some embodiments, the height of the spacers may be unevenly distributed so that the spacers do not need to be deformed. In some embodiments, the second shell 535 may be molded according to the desired shape, and then spacers are formed on the second shell 535 . In some embodiments, the separator layer may be a continuous mesh layer or a porous layer. A single layer may consist of two or more sublayers.

In some embodiments, the plurality of spacers 615 may comprise copper or polymer materials. In some embodiments, the plurality of spacers may comprise any type of metal.

6A and 6B illustrate a first portion of the plurality of spacers 815B having an extended thickness and/or lower height thermal ground plane 800 . The thermal ground plane 800 may further have a second portion of the plurality of spacers 815A, wherein the second portion of the plurality of spacers 815A has an extended thickness and/or a higher height. A first portion of the plurality of spacers 815B may be disposed in the vapor core 520 portion with a first thickness, and a second portion of the plurality of spacers 815A may be disposed in the vapor core 520 with a second thickness. The first thickness may be smaller than the second thickness. In some embodiments, the first portion of the plurality of spacers 815B having an expanded thickness and/or lower height may be compressible. FIGS. 7A and 7B illustrate thermal ground plane 800 with a first portion of plurality of spacers 915B having an expanded thickness and/or lower height and possibly a corrugated or extruded profile formed by thermal ground plane 900 compression.

In some embodiments, the grid structure 515 may be disposed on the plurality of spacers 815A, 815B and/or 915B and/or between the plurality of spacers 815A, 815B and/or 915B and the first housing 510 .

FIG. 8 shows a thermal ground plane 1000 in accordance with some embodiments. The grid structure 515 within the thermal ground plane 1000 may be disposed between the plurality of spacers 815A, 815B and/or 915B. In some embodiments, a plurality of spacers 815A, 815B and/or 915B may be provided on the second housing.

Figures 9A, 9B, 10A, and 10B illustrate the steps of making a thermal ground plane with a variable thickness steam core in accordance with some embodiments. In some embodiments, the plurality of spacers 715 may include spacers with spring-like mechanical properties. For example, the plurality of spacers 715 may include micro-springs, micro-suspension plates, copper micro-flexures, other metallic materials, or elastic polymers encapsulated by hermetic seals. In some embodiments, the mechanical stiffness of the plurality of spacers 715 may be sufficient to maintain a low vacuum in the steam core. In some embodiments, the stiffness of the plurality of spacers 715 and/or the first housing 510 and/or the second housing 535 is insufficient such that the shape of the vapor core 520 changes with the pressure of the mobile system housing (eg, housing 505 ) The construction of circuit board 530 (and/or circuit elements 525 and/or 540 ) is shaped. In areas with voids, the steam core 520 can naturally expand. In some embodiments, the heights or sizes of the plurality of spacers 715 may not be uniformly distributed, and therefore, the deformation amount of the plurality of spacers 715 may be designed to accommodate different gaps. In some embodiments, the plurality of spacers 715 may be formed on the housing after the first housing 510 and/or the second housing 535 are formed into a desired shape. For example, the plurality of spacers 715 may be continuous mesh layers or porous layers. A single layer may consist of 2 or more sublayers.

In some embodiments, the plurality of spacers may be resilient (eg, similar to spring masses), allowing the thermal ground plane to self-adjust and/or deform into the circuit board gap. In some embodiments, the vapor core 520 may include a plurality of elastic spacers of variable height. In some embodiments, the elastic or spring-like spacer and the first shell 510 and/or the second shell 535 can deform according to the voids used to enhance gas phase conduction. In some embodiments, the coolant may optionally be operated under positive pressure to push the first housing 510 and/or the second housing 535 outwardly so that the coolant itself acts as a spring-like material.

11 shows a thermal ground plane 1300 that may include additional wicking structures 1320 disposed within the vapor core, and the thermal ground plane may be placed on circuit elements (eg, circuit elements that can generate more heat than other circuit elements) ) in the nearby area. For example, additional wicking structures 1320 can be used to reduce the high heat flux generated by some circuit elements. In some embodiments, the additional wicking structures 1320 may be connected, contacted, and/or coupled to one or more of the additional wicking structures 515 and/or the first shell 510 . In some embodiments, the additional wicking structure 1320 may be made of copper, stainless steel, titanium, ceramics, or polymers. In some embodiments, the additional wicking structure 1320 may include or be coated with additional layers to prevent it from reacting with fluids, if desired.

In some embodiments, an additional wicking structure 1320 may be attached to the wicking structure 515, for example, to provide continuous evaporation of liquid water. The vapor temperature in the region near the heat generating chip (eg, circuit element) is high, and the corresponding gas phase conduction is good. This allows the steam core thickness to be reduced in this hot zone without degrading performance.

FIG. 12 shows a thermal ground plane 1400 with a first housing 1410 having a variable height that can accommodate the contours of the device housing 505 . In some embodiments, voids associated with device housing 505 may be utilized to enhance gas phase conduction. The device enclosure 505 of each system is an important element of thermal management. For example, heat can be carried from circuit elements 525 and 540 into the ambient air. In some embodiments, the purpose of thermal management may be to dissipate heat from heat generating circuit elements 525 and 540 to device housing 505 for cooling by the surrounding environment. Many device housings (eg, device housing 505) may not be flat. For example, the device housing can have three-dimensional shapes to suit different design requirements. This results in various voids that may exist in the housing of the device. According to some embodiments, the vapor core 820 of the thermal ground plane 1400 may have a variable thickness formed to accommodate the three-dimensional shape of the device housing 505 . In some embodiments, the wicking structure 815 may be disposed near the circuit board 530 and/or the circuit elements 525 and/or 540 .

13 illustrates a thermal ground plane 1500 having a variable height first housing 1410 and a variable height second housing 1535 in accordance with some embodiments. For example, the first housing 1410 may have a variable height that accommodates the device housing 805 . For example, the second housing 1535 may have a variable height that accommodates the circuit board 530 and/or circuit elements 525 and 540 . In this example, the wicking structure 1515 may contact, attach, couple, grow, and be disposed on the second housing 1535.

14 illustrates a thermal ground plane 1600 having a variable height first housing 1410 and a variable height second housing 1535 in accordance with some embodiments. For example, the first housing 1410 may have a variable height that accommodates the device housing 805 . For example, the second housing 1535 may have a variable height that accommodates the circuit board 530 and/or circuit elements 525 and 540 . In this example, the wicking structure 1615 may contact, attach, couple, grow, and be disposed on the first housing 1410 .

In some embodiments, thermal ground plane 1500 and/or thermal ground plane 1600 voids in device housing 805 and/or circuit board 530 (and/or circuit elements 525 and/or 540 ) may be used to enhance vapor phase conduction. In some embodiments, one or more wicking structures may be positioned adjacent to the first housing 805 and/or the second housing 835, wherein the first housing 805 and/or the second housing 835 are positioned within the circuit elements nearby.

Some embodiments include circuit boards having one or more voids, wherein the voids are created, fabricated, designed, etc. to optimize vapor phase conduction within an associated thermal ground plane. The design of a typical circuit board can be optimized by a combination of electrical, mechanical, thermal, and/or other performance metrics. The voids can also be optimized. For example, the circuit board may be designed to enhance vapor phase conduction within the vapor core associated with the thermal ground plane. While voids are always present, for example, their arrangement can be optimized to enhance gas phase conduction. Key considerations also relate to size, including the gap of the void and/or the temperature of the steam within the void. When the steam temperature is low, the gas phase conduction may not be effective. In some cases, it may be necessary to increase the size of the vapor core in areas away from heat sources (eg, circuit components). In these areas, the steam temperature is lower, and for efficient conduction, additional gaps are required.

Some embodiments may further include a device housing having voids, wherein the voids are created, arranged, designed, assembled, etc., for optimizing gas phase conduction. A typical device enclosure can be designed with a combination of electrical, mechanical, thermal, and other performance considerations. The voids can also be optimized. In some embodiments, voids may be used to enhance vapor phase conduction and related thermal performance of the thermal ground plane. For example, circuit boards and/or housings (or housings) may represent critical components in mobile systems. Voids are always present, so the void placement can be optimized to enhance the relative thermal performance of gas phase conduction and thermal ground planes. For example, primary considerations may include size, gaps including voids, and steam temperature within the voids.

The term "substantially" means 5% or 10% of the indicated value or within manufacturing tolerance.

Various embodiments are disclosed. Various embodiments may be combined in part or in whole to form other embodiments.

Numerous specific details are set forth herein in order to provide a thorough understanding of the claimed subject matter. However, it will be understood by those skilled in the art that the claimed subject matter may be practiced without these specific details. In other instances, methods, devices, or systems that are well known to those of ordinary skill have not been described in detail so as not to obscure the claimed subject matter.

The method embodiments disclosed herein may be performed while a computing device is running. The order of the unit blocks in the above examples may vary, eg, the unit blocks may be reordered, combined and/or decomposed into sub-blocks. Certain unit blocks or processes can be executed in parallel.

The terms "adapted to" or "configured to" as used herein are intended to be open and inclusive and do not preclude the device being adapted or configured to perform other tasks or steps. In addition, the term "based on" also has an open and inclusive meaning, in fact, a process, step, calculation or other action "based on" one or more of the recited conditions or values may also be based on the recited condition or value. A condition or value other than a condition or value. The headings, lists, and numbers included herein are for convenience of explanation only and are not intended to be limiting.

While specific embodiments of the present subject matter have been described in detail, it will be appreciated that such embodiments may be readily altered, varied, and generated by those skilled in the art after gaining an understanding of the foregoing. equivalent. Therefore, it is to be understood that the present disclosure is described by way of example only, and is not intended to be limiting, and does not preclude modifications, changes and/or additions to the subject matter that would be apparent to those of ordinary skill in the art.

Numerous specific details are set forth herein in order to provide a thorough understanding of the claimed subject matter. However, one skilled in the art will understand that the claimed subject matter may be practiced without these specific details. In other instances, methods, devices, or systems that are well known to those of ordinary skill have not been described in detail so as not to obscure the claimed subject matter.

The method embodiments disclosed herein may be performed while a computing device is running. The order of the unit blocks in the above examples may vary, eg, the unit blocks may be reordered, combined and/or decomposed into sub-blocks. Certain unit blocks or processes can be executed in parallel.

Some embodiments of the present application also provide the following examples.

Example 1. A thermal ground plane comprising:

the first shell;

a second housing, the second housing and the first housing are configured to enclose a working fluid;

an evaporator zone disposed at least partially on at least one of the first shell and the second shell;

a condenser zone disposed at least partially on at least one of the first shell and the second shell;

a wicking structure disposed between the first shell and the second shell;

A steam core that is at least partially defined by a gap between the first shell and the second shell, wherein the thickness of the gap varies between the first shell and the second shell.

Example 2. The thermal ground plane of Example 1, wherein the gap is designed to provide room for an enlarged core gap.

Example 3. The thermal ground plane of example 1 or 2, wherein the thickness of the gap adjacent the evaporator region is less than the average gap thickness.

Example 4. The thermal ground plane of Examples 1, 2, or 3, wherein the thickness of the gaps not adjacent to the evaporator region is greater than the average gap thickness.

Example 5. The thermal ground plane of any of Examples 1 to 4, wherein either or both of the first and second housings comprise a material that stretches and/or shrinks to expand the gap.

Example 6. The thermal ground plane of any of Examples 1 to 5, wherein the wicking structure layer is in contact with either or both of the first shell layer and/or the second shell.

Example 7. The thermal ground plane of any of Examples 1 to 6, further comprising additional wicking structures in contact with the wicking structures and the evaporator region.

Example 8. The thermal ground plane of any of Examples 1 to 7, wherein the gap is defined by an internal pressure above ambient pressure.

Example 9. The thermal ground plane of any one of Examples 1 to 8, further comprising a plurality of spacers disposed within the gap.

Example 10. The thermal ground plane of Example 9, wherein the plurality of spacers comprise copper or polymer encapsulated by a hermetic seal.

Example 11. The thermal ground plane of Example 9, wherein the plurality of spacers can include springs.

Example 12. The thermal ground plane of Example 9, wherein the plurality of spacers can comprise a resilient material.

Example 13. The thermal ground plane of Example 9, wherein the thickness of the gap may be less than 50 μm.

While specific embodiments of the present subject matter have been described in detail, it will be appreciated that such embodiments may be readily altered, varied, and generated by those skilled in the art after gaining an understanding of the foregoing. equivalent. Therefore, it is to be understood that the present disclosure is described by way of example only, and is not intended to be limiting, and does not preclude modifications, changes and/or additions to the subject matter that would be apparent to those of ordinary skill in the art.

Those skilled in the art can understand that the above-mentioned embodiments are specific examples for realizing the present invention, and in practical applications, various changes in form and details can be made without departing from the spirit and the spirit of the present invention. scope.

Claims (10)

1. A thermal ground plane, comprising:

a first housing;

a second housing, the second housing and the first housing configured to enclose a working fluid;

an evaporator zone disposed at least partially on at least one of the first housing and the second housing;

a condenser zone at least partially disposed on at least one of the first shell and the second shell;

a wicking structure disposed between the first housing and the second housing;

a vapor core at least partially defined by a gap between the first and second housings, wherein a thickness of the gap varies between the first and second housings, the vapor core for vapor transport between the evaporator region and the condenser region.

2. The thermal ground plane according to claim 1, wherein the gap is designed to provide space for expanding the vapor core gap.

3. The thermal ground plane according to claim 1, wherein a thickness of a gap adjacent to the evaporator region is less than an average gap thickness.

4. The thermal ground plane according to claim 1, wherein a thickness of the gap not adjacent to the evaporator region is greater than an average gap thickness.

5. The thermal ground plane according to claim 1, wherein either or both of the first shell and the second shell comprise a material that stretches and/or contracts to expand a gap.

6. The thermal ground plane of claim 1, wherein the wicking structure layer is in contact with either or both of the first shell layer and/or the second shell.

7. The thermal ground plane according to claim 1, further comprising an additional wicking structure in contact with the wicking structure and the evaporator region.

8. The thermal ground plane according to claim 1, wherein the gap is defined by an internal pressure higher than an ambient pressure.

9. The thermal ground plane according to any one of claims 1 to 8, further comprising a plurality of spacers disposed within the gap.

10. The thermal ground plane according to claim 9, wherein the plurality of spacers comprise copper or a polymer encapsulated by a hermetic seal.

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