WO2017041708A1

WO2017041708A1 - Vapor chamber for mobile communication devices

Info

Publication number: WO2017041708A1
Application number: PCT/CN2016/098296
Authority: WO
Inventors: Ka Kit TSUI
Original assignee: Fantome Limited
Priority date: 2015-09-07
Filing date: 2016-09-07
Publication date: 2017-03-16

Abstract

The vapor chamber (100) comprises a heating plate 110 for attaching to the heat source (180) and absorbing the heat therefrom, and a cooling plate (120) for dissipating the heat received from the heating plate (110) to an ambient space 185 outside the host device (181). The vapor chamber (100) further comprises a support frame (130) between the heating plate (110) and the cooling plate (120). The support frame (130) is mainly used as a mechanical frame for supporting the vapor chamber (100), and usually includes provisions, such as thread pins and screwing hooks, for mounting to the host device (181) or directly to the heat source (180). In particular, the heating plate (110), the support frame (130) and the cooling plate (120) are stacked and integrated together to form a rigid container (205) having a sealed space (210) therein. The rigid container (205) is used to provide mechanical support to the host device (181) when the host device (181) is integrated with the vapor chamber (100). Note that the rigid container (205) forms a bulk of the vapor chamber (100).

Description

VAPOR CHAMBER FOR MOBILE COMMUNICATION DEVICES

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to, and the benefit of, U.S. Provisional Patent Application No. 62/215,056, filed on September 7, 2015, which is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates generally to thermal cooling methods, systems, and devices. More specifically, the present invention relates to the cooling of mobile communication devices using vapor chambers.

BACKGROUND

Electronic components such as microprocessors and wireless communication modules generate a lot of heat and the dissipation of heat is necessary for optimal operations. As the size of electronic devices is reduced relentlessly and at the same time their functionalities ever increase, it presents a great challenge to the design of cooling systems for these electronic devices.

One effective cooling system is based on a vapor chamber that is placed immediately adjacent to the heat generating components, channeling and dissipating heat by convection and radiation. Typically, a vapor chamber is a vessel structure filled with a working liquid and its vapor. When the working liquid comes in contact with the internal wall of the hot side of the vapor chamber, it vaporizes. The vapor then travels to the cool side of the vapor chamber and condenses back into liquid form, releasing latent heat of vaporization.

Structures of vapor chambers have been suggested in a number of disclosures, e.g., US20140352926. However, the difficulty of deploying traditional vapor chambers in mobile communication devices such as mobile phones is the bulkiness of the vapor chambers. Mobile phones of today place very demanding requirements on size and rigidity. Furthermore, a user usually holds his or her mobile phone not in a horizontal manner. The working liquid in the vapor chamber is easily diverted to one end of the vapor chamber by gravitational pull, seriously affecting the thermal transfer efficiency of the vapor chamber.

There is a need in the art for a vapor chamber that is compact and mechanically strong for use in a mobile communication device and that resists the gravitational pull of the working liquid therein when the vapor chamber is not oriented horizontally.

SUMMARY OF THE INVENTION

The present invention provides a vapor chamber for dissipating heat from a heat source and providing mechanical support to a host device having the heat source.

The vapor chamber comprises a heating plate for attaching to the heat source and absorbing the heat therefrom, and a cooling plate for dissipating the heat received from the heating plate to an ambient space outside the host device. Moreover, a support frame between the heating plate and the cooling plate is further included in the vapor chamber. The heating plate, the support frame and the cooling plate are stacked and integrated together to form a rigid container having a sealed space therein. The rigid container provides mechanical support to the host device when the host device is integrated with the vapor chamber. In the sealed space, there is a working fluid for transferring the heat from the heating plate to the cooling plate. The working fluid is selected such that: when the working fluid in a liquid form contacts the heating plate, the working fluid is vaporized into a vapor form to absorb the heat from the heating plate； and when the vaporized working fluid arrives at the cooling plate, the working fluid is condensed back to the liquid form to release the heat therein to the cooling plate. A plurality of porous columns is also placed in the sealed space. Each of the porous columns extends from the cooling plate to the heating plate. In addition, the porous columns are made of wick for absorbing the condensed working fluid from the cooling plate and drawing the condensed working fluid back to the heating plate by capillary action. Hence, the condensed working fluid returns to the heating plate without substantially diverting away from the heating plate by gravitational pull when the heating plate and the cooling plate are vertically oriented.

Preferably, the cooling plate comprises protrusions or recessions located on a side of the cooling plate facing the ambient space for assisting heat dissipation. The support frame may include one or more thread pins for assembling with the host device. The heating plate and/or the cooling plate may be made of aluminum, steel, or titanium. The support frame may be made of metal.

The vapor chamber is advantageously used for the host device that is a mobile communication device. The vapor chamber may be attached to the heat source by a thermal pad or a thermal paste for efficiently transmitting heat from the heat source to the heating plate. In one option, the rigid container has a thickness from 0.2mm to 0.4mm for minimizing an increase of thickness to the mobile communication device.

Additionally, an assembly for dissipating heat from a heat source of the mobile communication device and providing mechanical support to the mobile communication device is obtainable by having a plurality of vapor chamber units stacked and integrated together to provide reinforced mechanical strength to the assembly. Each of the vapor chamber unit is realized as any of the embodiments of the vapor chamber as disclosed herein. In one option, the number of the vapor chamber units is two.

Other aspects of the present invention are disclosed as illustrated by the embodiments hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an exploded view of a vapor chamber in accordance with an exemplary embodiment of the present invention.

FIG. 2 depicts an integrated form of the vapor chamber of FIG. 1.

FIG. 3 illustrates the advantage of the vapor chamber by depicting the cases that (a) a cooling plate and a heating plate of the vapor chamber are horizontally oriented, and (b) the two plates are vertically oriented.

FIG. 4 depicts a cross-sectional view of the vapor chamber for illustrating some optional features.

DETAILED DESCRIPTION

The present invention addresses the unmet needs of the use of vapor chambers in mobile communication devices (e.g., smartphones and tablets) by providing a novel mechanical design of a vapor chamber. Although the present invention is particularly useful for mobile communication devices, the present invention is not limited only to these devices. The present invention is also useful to any device that generates heat, such as a notebook computer, which has processors that generate quite a lot of heat during operation. For simplicity, the present invention is described hereinafter with reference to a mobile communication device for illustration. Based on the teachings disclosed herein, those skilled in the art are easy to apply the present invention to any device other than the mobile communication device.

The vapor chamber as disclosed herein is used for dissipating heat from a heat source and providing mechanical support to a host device having the heat source. For example, the heat source is an integrated circuit mounted on a printed circuit board (PCB) and the host device is the PCB. The PCB may be used in a mobile communication device or any other electronic device. In particular, the vapor chamber is configured to substantially maintain efficiency of heat dissipation regardless of the orientation of the vapor chamber. The heat dissipation efficiency is essentially maintained even in the presence of gravitational pull when the vapor chamber is oriented vertically.

To make the vapor chamber thin, the vapor chamber is formed by stacking a plurality of layers together. FIG. 1 depicts an exemplary design of the vapor chamber in an exploded view. The integrated form of this design is depicted in FIG. 2. The vapor chamber (labeled as 100) comprises a heating plate 110 for attaching to the heat source (labeled as 180) and absorbing the heat therefrom, and a cooling plate 120 for dissipating the heat received from the heating plate 110 to an ambient space 185 outside the host device (labeled as 181) . The vapor chamber 100 further comprises a support frame 130 between the heating plate 110 and the cooling plate 120. The support frame 130 is mainly used as a mechanical frame for supporting the vapor chamber 100, and usually includes provisions, such as thread pins and screwing hooks, for mounting to the host device 181 or directly to the heat source 180. In particular, the heating plate 110, the support frame 130 and the cooling plate 120 are stacked and integrated together to form a rigid container 205 having a sealed space 210 therein. The rigid container 205 is used to provide mechanical support to the host device 181 when the host device 181 is integrated with the vapor chamber 100. Note that the rigid container 205 forms a bulk of the vapor chamber 100.

Inside the sealed space 210, there is a working fluid for transferring the heat from the heating plate 110 to the cooling plate 120. The working fluid is selected to achieve the following effect. When the working fluid in a liquid form contacts the heating plate 110, the working fluid is vaporized into a vapor form to absorb the heat from the heating plate 110. When the vaporized working fluid arrives at the cooling plate 120, the working fluid is condensed back to the liquid form to release the heat therein to the cooling plate 120, whereby the heat collected by the cooling plate 120 is dissipated to the ambient space 185.

The vapor chamber 100 further comprises a layer of wick 140 for assisting the condensed working fluid in the liquid form to cycle back to the heating plate 110. The layer of wick 140 is realized as a plurality of porous columns 220a-e in the sealed space 210. Each of the porous columns 220a-e, being porous for providing a passage for the condensed working fluid to travel, extends from the cooling plate 120 to the heating plate 110. Furthermore, each of the porous columns 220a-e is made of wick for absorbing the condensed working fluid from the cooling plate 120 and drawing the condensed working fluid back to the heating plate 110 by capillary action.

The advantage of using the layer of wick 140 in the form of the plurality of porous columns 220a-e extended from the cooling plate 120 to the heating plate 110 is illustrated with the aid of FIG. 3. FIG. 3 (a) depicts a first case that the cooling plate 120 and the heating plate 110 are horizontally oriented. FIG. 3 (b) illustrates a second case that the two

plates

120, 110 are vertically oriented. As used herein, a horizontal orientation and a vertical orientation are defined with reference to a reference vertical direction 301. The reference vertical direction 301 is the direction of gravitational pull. For the first case, it is apparent that the movement of the condensed working fluid, in the liquid form, from the cooling plate 120 to the heating plate 110 is assisted by the gravity. It is entirely different for the second case. When the two

plates

120, 110 are vertically oriented, the gravity pulls the condensed working liquid downwards, hampering the travel of the condensed working fluid back to the heating plate 110 and potentially reducing the heat transfer efficiency achievable by the vapor chamber 100. The presence of the porous columns 220a-e offsets this hampering effect. Consider the subplot (b1) , which depicts a cross-section of the sealed space 210. The heat of the heat source 180 is absorbed by the heating plate 110, which then heats up the working fluid to form vaporized working fluid 360. The vaporized working fluid 360 that arrives at the cooling plate 120 is cooled down to form a liquid film 370 of condensed working fluid. The liquid film 370 falls downward by the gravity to meet a porous column 342. The porous column 342 absorbs the condensed working liquid from the liquid film 370 and draws the condensed working liquid (labeled as 372) to travel along the porous column 342 by capillary action. By the capillary action of the porous column 342, the condensed working liquid 372 returns to the heating plate 110 without substantially diverting away from the heating plate 110 by gravitational pull when the heating plate 110 and the cooling plate 120 are vertically oriented.

FIG. 4 depicts a cross-sectional view of the vapor chamber 100 for illustrating some optional, auxiliary features. Preferably, the cooling plate 120 comprises protrusions or recessions (both collectively indicated as 425) located on a side of the cooling plate 120 facing the ambient space 185 for assisting heat dissipation. The support frame 130 may include one or more thread pins 435 for assembling with the host device 181.

In accordance with one embodiment of the present invention, the vapor chamber 100 or the rigid container 205 is of 0.2 –0.4 mm think for minimizing an increase of thickness to a mobile communication device when the vapor chamber 100 is integrated therein. Furthermore, the vapor chamber 100 can even be used to replace (in place of) a traditional liquid crystal display (LCD) shield and/or a mid-frame of the mobile communication device as a supporting structure of the mobile communication device such that an overall thickness of the mobile communication device can remain the same.

The heating plate 110 and/or the cooling plate 120 of the vapor chamber 100 can be made of copper, which is good in heat conduction. However, as copper is a rather soft metal and easily deformed, to strengthen the vapor chamber 100 as a supporting structure, aluminum may be used to make the heating plate 110 and/or the cooling plate 120. Steel, titanium, or other strong and heat-conductive metal may also be used to in place of aluminum. The support frame 130 is preferably made of metal.

To attach the vapor chamber 100 to the heat source 180, one may use a thermal pad or a thermal paste for an advantage of efficiently transmitting heat from the heat source 180 to the heating plate 110.

In another embodiment, two vapor chambers can also be stacked together for providing the strength as a supporting structure of the mobile communication device while still keeping a small size for fitting to the mobile communication device.

Similarly, an assembly for dissipating heat from a heat source of the mobile communication device and providing mechanical support to the mobile communication device is obtainable by comprising a plurality of vapor chamber units stacked and integrated together to provide reinforced mechanical strength to the assembly. An individual vapor chamber unit is realized as any one of the embodiments of the vapor chamber 100 as disclosed above.

The present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

A vapor chamber for dissipating heat from a heat source and providing mechanical support to a host device having the heat source, comprising:

a heating plate for attaching to the heat source and absorbing the heat therefrom；

a cooling plate for dissipating the heat received from the heating plate to an ambient space outside the host device；

a support frame between the heating plate and the cooling plate, wherein the heating plate, the support frame and the cooling plate are stacked and integrated together to form a rigid container having a sealed space therein, the rigid container providing mechanical support to the host device when the host device is integrated with the vapor chamber；

a working fluid in the sealed space for transferring the heat from the heating plate to the cooling plate, wherein the working fluid is selected such that when the working fluid in a liquid form contacts the heating plate, the working fluid is vaporized into a vapor form to absorb the heat from the heating plate, and when the vaporized working fluid arrives at the cooling plate, the working fluid is condensed back to the liquid form to release the heat therein to the cooling plate； and

a plurality of porous columns in the sealed space, each of the porous columns extending from the cooling plate to the heating plate, wherein the porous columns are made of wick for absorbing the condensed working fluid from the cooling plate and drawing the condensed working fluid back to the heating plate by capillary action, causing the condensed working fluid to return to the heating plate without substantially diverting away from the heating plate by gravitational pull when the heating plate and the cooling plate are vertically oriented.
The vapor chamber of claim 1, wherein the host device is used in a mobile communication device.
The vapor chamber of claim 1, wherein the cooling plate comprises protrusions or recessions located on a side of the cooling plate facing the ambient space for assisting heat dissipation.
The vapor chamber of claim 1, wherein the support frame is made of metal.
The vapor chamber of claim 1, wherein the support frame includes one or more thread pins for assembling with the host device.
The vapor chamber of claim 1, wherein the heating plate is made of aluminum, steel, or titanium.
The vapor chamber of claim 1, wherein the cooling plate is made of aluminum, steel, or titanium.
The vapor chamber of claim 1, wherein the rigid container has a thickness from 0.2mm to 0.4mm.
A mobile communication device comprising a vapor chamber of any of claims 1-8 for dissipating heat from a heat source of the mobile communication device and providing mechanical support to the mobile communication device.
The mobile communication device of claim 9, wherein the vapor chamber is attached to the heat source by a thermal pad or a thermal paste for efficiently transmitting heat from the heat source to the heating plate.
The mobile communication device of claim 9, further configured to be a smartphone or a tablet.
A mobile communication device comprising an assembly for dissipating heat from a heat source of the mobile communication device and providing mechanical support to the mobile communication device, wherein the assembly comprises a plurality of vapor chamber units stacked and integrated together to provide reinforced mechanical strength to the assembly, an individual vapor chamber unit being realized as the vapor chamber of any of claims 1-8.
The mobile communication device of claim 12, wherein the heating plate of the vapor chamber unit at one end of the assembly is attached to the heat source by a thermal pad or a thermal paste for efficiently transmitting heat from the heat source to the aforesaid heating plate.
The mobile communication device of claim 12, wherein the number of the vapor chamber units is two.
The mobile communication device of claim 12, further configured to be a smartphone or a tablet.
A mobile communication device, comprising:

an integrated circuit mounted on a printed circuit board (PCB) ； and

the vapor chamber of any of claims 1-8 for dissipating heat from the integrated circuit and providing mechanical support to the PCB.
The mobile communication device of claim 16, wherein the vapor chamber is attached to the integrated circuit by a thermal pad or a thermal paste for efficiently transmitting heat from the integrated circuit to the heating plate.
The mobile communication device of claim 16, further configured to be a smartphone or a tablet.