US20190249927A1

US20190249927A1 - Heat transfer device

Info

Publication number: US20190249927A1
Application number: US16/264,836
Authority: US
Inventors: Sun-Ki Kim
Original assignee: Joinset Co Ltd
Current assignee: Joinset Co Ltd
Priority date: 2018-02-12
Filing date: 2019-02-01
Publication date: 2019-08-15
Also published as: KR20190097475A; CN110167317A

Abstract

A heat transfer device configured to be independently fixed and densely mounted. The heat transfer device includes: a main body formed of a metallic material and forming a tube sealed to maintain a vacuum therein; and a thermally conductive layer having elasticity and adhered around the main body.

Description

REFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit of Korean Patent Application No. 10-2018-0016952 filed on Feb. 12, 2018, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a heat transfer device, and more particularly, to a heat transfer device configured to be independently fixed and easily mounted in high density.

BACKGROUND OF THE INVENTION

In recent years, electronic components or modules have been highly integrated and designed to have high performance, and thus more heat is generated from such electronic components or modules. In addition, as the size of products decreases, heat is more densely generated. Therefore, measures for dissipating heat become more important.
This situation is more noticeable in mobile terminals such as smartphones and tablets, and direct cooling or heat transfer is necessary to handle generated heat.
Heat transfer devices such as thermal sheets or graphite sheets have high heat transfer performance in a horizontal direction. However, heat pipes, heat spreaders, or vapor chambers (hereinafter, these devices will be collectively referred to as heat pipes) are used for the case in which heat transfer is insufficient. In general, the apparent thermal conductivity of heat pipes is several times to several tens of times the apparent thermal conductivity of a simple metal such as copper or aluminum.
As is well known, such a heat pipe has a tubular structure forming a vacuum therein. For example, if heat is generated from a heat-generating electronic component such as a processor placed in contact with an end of a heat pipe, a small amount of a refrigerant such as water or ethylene glycol is vaporized by the heat, and the vaporized refrigerant is pushed toward the opposite end of the heat pipe by the pressure difference between gas and liquid. Then, the vaporized refrigerant is cooled and condensed into liquid. As this process repeats, heat generated from the processor is transferred to another place, and thus the processor is cooled and prevented from being overheated.
Heat pipes have already been widely used in general personal computers, and in recent years, heat pipes have been used to transfer heat generated from processors of smartphones.
For example, a heat pipe may be used in a smartphone by forming an accommodation groove in a metal case of the smartphone, attaching a piece of thermally conductive double-sided adhesive tape to the bottom of the accommodation groove, and attaching a surface of the heat pipe to the piece of thermally conductive double-sided adhesive tape to fix the heat pipe to the metal case.
Therefore, if a heat pipe has a complex shape such as a bent shape and a large length, it is difficult to manufacture double-sided adhesive tape according to the shape of the heat pipe, and it is more difficult to manufacture double-side adhesive tape having a small thickness or a long length according to the shape of an accommodation groove to install the heat pipe in the accommodation groove.
In addition, since double-sided adhesive tape is additionally used to fix such a heat pipe, it is inconvenient to densely mount the heat pipe, and additional costs are incurred.
In addition, since heat pipes are formed of a metallic material, the heat pipes may not be elastically brought into thermal contact with heat sources or metal cases for cooling, and thus it is difficult to transfer heat rapidly and reliably.
Therefore, in general, a thermally conductive member having elasticity such as a thermal pad, thermal grease, or a thermal gap filler has to be additionally placed between a heat pipe and a heat source or a cooling case.
In particular, when a heat pipe formed of a metallic material is bought into contact with and coupled to a plurality of cooling metal fins, the effect of heat transfer is not satisfactory because of direct metal-to-metal contact.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a simple heat transfer device configured to be independently fixed without additionally using a thermally conductive adhesive material.
Another object of the present invention is to provide a heat transfer device configured to effectively transfer heat even when the heat transfer device is in contact with an object having high hardness.
Another object of the present invention is to provide a heat transfer device configured to be densely mounted.
Another object of the present invention is to provide an economical heat transfer device having fewer components and configured to be easily installed.
According to an aspect of the present invention, there is provided a heat pipe having improved heat transfer performance, the heat pipe including: a main body formed of a metallic material and forming a tube sealed to maintain a vacuum therein; and a thermally conductive layer having elasticity and flexibility and adhered around the main body.
According to another aspect of the present invention, there is provided a heat pipe having improved heat transfer performance, the heat pipe including: a main body formed of a metallic material and forming a tube sealed to maintain a vacuum therein; a first thermally conductive layer having elasticity and a self-adhesive outer surface and adhered to a surface of the main body; and a second thermally conductive layer having elasticity and a self-adhesive outer surface and adhered to an opposite surface of the main body.
According to another aspect of the present invention, there is provided a heat transfer device comprising: a main body formed of a metallic material and forming a tube sealed to maintain a vacuum therein; a thermally conductive layer having elasticity and flexibility and adhered around the main body; and a thermally conductive particle layer formed of thermally conductive particles attached to an outer surface of the thermally conductive layer.
Therefore, since thermally conductive double-sided adhesive tape or a thermally conductive adhesive is not additionally used to fix the heat transfer device to an accommodation groove of a metal case, the heat transfer device may be easily fixed and densely installed even in a small space. Thus, the heat transfer device is economical.
In addition, since the contact area between the heat transfer device and the accommodation groove of the metal case is increased, heat may be transferred rapidly and reliably.
In addition, since the heat transfer device is configured to be elastically brought into contact with a metal case or a heat source, heat may be effectively transferred.
In addition, a thermal sheet having self-adhesion may be used to easily arrange the heat transfer device on release paper or film.

BRIEF DESCRIPTION OF THE DRAWINGS

The above objects and other advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:

FIG. 1 is a view illustrating a state in which a heat pipe is applied to a smartphone according to an embodiment of the present invention;

FIG. 2 is a partial perspective view illustrating a cross-section of the heat pipe;

FIGS. 3A and 3B are views illustrating how the heat pipe is placed in a accommodation groove; and

FIG. 4 is a cross-sectional view illustrating a heat pipe according to another embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Technical terms used herein are only for explaining specific embodiments while not limiting the present invention. In addition, unless otherwise defined, technical terms used herein have the same meaning as commonly understood by those of ordinary skill in the art and will not be interpreted in an overly broad or narrow sense. In addition, if technical terms used herein are incorrect to exactly express the idea of the present invention, the technical terms should be interpreted as terms by which those of ordinary skill in the art can correctly understand the idea of the present invention. In addition, general terms used herein may be interpreted as defined in dictionaries or according to the contextual meanings, and should not be interpreted in an overly narrow sense.
FIG. 1 illustrates a state in which a heat pipe 100 is applied to a smartphone according to an embodiment of the present invention.
A battery 14 may be provided on a back cover 10 of the smartphone, and a circuit board 16 on which a plurality of electronic components are mounted may be provided in a region surrounding the battery 14.
In FIG. 1, the back cover 10 formed of a metallic material is shown as an example of a heat releasing object. However, the present invention is not limited thereto. For example, another metal case of a heat generating unit may be considered.
A heat source generating a large amount of heat such as an application processor (AP) among the electronic components mounted on the circuit board 16 is brought into contact with the heat pipe 100 such that heat generated from the heat source may be rapidly dissipated through the back cover 10.
To this end, the heat pipe 100 is fixedly inserted into an accommodation groove 12 formed in the back cover 10, and as described later, the heat pipe 100 may be fixed to the back cover 10 owing to self-adhesion of a thermally conductive layer 120.
FIG. 2 is a partial perspective view illustrating a cross-section of the heat pipe 100.
The heat pipe 100 includes: a metallic main body 110 forming a tube sealed to maintain a vacuum therein; and the thermally conductive layer 120 having elasticity and adhered around the main body 110.
The main body 110 is formed of a metallic material such as copper or aluminum.
The thermally conductive layer 120 may be a thermal sheet formed of a thermally conductive silicone rubber or a thermally conductive acrylic resin. In this case, the thermal sheet may surround the main body 110, and both widthwise ends of the thermal sheet may be in contact with each other or may be separate from each other on a lower surface of the main body 110.
Alternatively, the thermally conductive layer 120 may be adhered or bonded to the main body 110 by dipping the main body 110 in a thermally conductive liquid-phase rubber or resin in which thermally conductive particles are mixed and dispersed and then curing the thermally conductive liquid-phase rubber or resin, or by spraying the thermally conductive liquid-phase rubber or resin onto an outer surface of the main body 110 and then curing the thermally conductive liquid-phase rubber or resin with heat or ultraviolet (UV) rays.
The thermally conductive layer 120 may form a closed loop in a width direction of the main body 110 and may extend in a length direction of the main body 110.
The thermally conductive layer 120 may include thermally-conductive, electrically-insulative particles such as ceramic powder, and thus the thermally conductive layer 120 may be electrically insulative. When only the thermal conductivity of the thermally conductive layer 120 is considered, the thermally conductive layer 120 may include metal powder, carbon powder, graphite powder, or graphite fiber. In this case, the thermally conductive layer 120 may have high thermal conductivity even though having electrical conductivity.
The thermally conductive layer 120 has elasticity and flexibility because the thermally conductive layer 120 has a structure based on a silicone rubber or acrylic resin. Therefore, the heat pipe 100 may be forcibly inserted into the accommodation groove 12 to bring the thermally conductive layer 120 into elastic contact with inner walls of the accommodation groove 12. In this case, since gaps between the heat pipe 100 and the accommodation groove 12 are filled with the thermally conductive layer 120, reliable thermal contact may be made over a relatively large area, thereby improving heat transfer efficiency.
The thickness of the thermally conductive layer 120 may be less than the thickness of the main body 110. In a non-limiting example, the thickness of the thermally conductive layer 120 may range from about 0.02 mm to about 0.3 mm.
The thermally conductive layer 120 may be discretely formed in the length direction of the thermally conductive layer 120. In this case, the total length of the thermally conductive layer 120 may be adjusted to be equal to or greater than half (½) the total length of the main body 110 for sufficient heat transfer.
The outer surface of the thermally conductive layer 120 may have self-adhesion. In this case, a portion of the thermally conductive layer 120 formed on a lower surface of the main body 110 may be adhered to the bottom of the accommodation groove 12 of the back cover 10. Therefore, the heat pipe 100 may be fixed to the accommodation groove 12 without additionally using a piece of thermally conductive double-sided adhesive tape or a thermally conductive adhesive.
In addition, the heat pipe 100 may be arranged on a sheet of release paper or release film by using the self-adhesion of the outer surface of the thermally conductive layer 120.
FIGS. 3A and 3B illustrate how the heat pipe 100 is placed in the accommodation groove 12.
The heat pipe 100 may be forcibly inserted into the accommodation groove 12 of the back cover 10 and elastically brought into contact with the bottom and both sidewalls of the accommodation groove 12 owing to the elasticity of the thermally conductive layer 120 so that thermal contact between the heat pipe 100 and the back cover 10 may be reliably improved.
In particular, if the outer surface of the thermally conductive layer 120 has self-adhesion, the thermally conductive layer 120 may be adhered to the bottom and/or both sidewalls of the accommodation groove 12 by the self-adhesion of the thermally conductive layer 120.
Therefore, unlike the related art, it is not necessary to use a piece of thermally conductive double-sided adhesive tape or a thermally conductive adhesive, or shape a piece of thermally conductive double-sided adhesive tape according to the shape of the heat pipe 100 so as to fix the heat pipe 100 to the accommodation groove 12. Therefore, simple manufacturing processes and low manufacturing costs may be guaranteed while enabling high-density mounting of the heat pipe 100.
In addition, since only the thermally conductive layer 120 having elasticity and surrounding the main body 110 of the heat pipe 100 is placed between the main body 110 and the accommodation groove 12 when fixedly inserting the heat pipe 100 into the accommodation groove 12, the heat pipe 100 may be easily mounted in the accommodation groove 12 and may have high thermal conductivity for improved heat transfer efficiency.
Likewise, on the heat pipe 100 fixedly inserted in the accommodation groove 12, the circuit board 16 or another heat source may be mounted directly or using a simple thermal sheet therebetween, thereby improving heat transfer efficiency and the yield of production.
In the above-described embodiment, the thermally conductive layer 120 entirely surrounds the main body 110. However, this is a non-limiting example. In another example, thermally conductive layers 120 may be adhered to only upper and lower surfaces of the main body 110.
In this case, the upper and lower thermally conductive layers 120 may have different thermal conductivity and self-adhesion characteristics.
For example, the upper thermally conductive layer 120 may have thermal conductivity less than the lower thermally conductive layer 120. In this case, the upper thermally conductive layer 120 may be brought into contact with a cooling case, and the lower thermally conductive layer 120 may be brought into contact with a heat source.
In addition, the upper thermally conductive layer 120 may have self-adhesion greater than the lower thermally conductive layer 120. In this case, the upper thermally conductive layer 120 may be brought into contact with a cooling case, and the lower thermally conductive layer 120 may be brought into contact with a heat source, such that when the cooling case is lifted, the heat pipe 100 may be on the cooling case owing to the upper thermally conductive layer 120.
FIG. 4 is a cross-sectional view illustrating a heat pipe 200 according to another embodiment.
In the current embodiment, thermally conductive particles are attached to an outer surface of a thermally conductive layer 220 to form a thermally conductive particle layer 230 by a high-temperature and high-pressure, vacuum, or plasma coating method as shown in an enlarged circle of FIG. 4, so as to substantially increase the surface area of the heat pipe 200.
The thermally conductive particles may be metal powder, carbon powder, graphite powder, ceramic powder, or carbon fiber having high thermal conductivity.
As a result, since the surface area of the thermally conductive layer 220 is increased, heat may rapidly transfer to the thermally conductive layer 220 and then to another object such as the back cover 10.
While the present invention has been described according to the embodiments, those of ordinary skill could understand that various modifications can be made from the embodiments. Therefore, the spirit and scope of the present invention are not limited to the embodiments, but should be construed by the appended claims.

Claims

What is claimed is:

1. A heat transfer device comprising:

a main body formed of a metallic material and forming a tube sealed to maintain a vacuum therein; and

a thermally conductive layer having elasticity and flexibility and adhered around the main body.

2. The heat transfer device of claim 1, wherein the thermally conductive layer is a thermal sheet extending in a length direction of the main body with both widthwise ends of the thermal sheet being in contact with each other or separate from each other.

3. The heat transfer device of claim 1, wherein the thermally conductive layer is adhered or bonded to the main body by dipping an outer surface of the main body in a thermally conductive liquid-phase rubber or resin in which thermally conductive particles are mixed and dispersed and then curing the thermally conductive liquid-phase rubber or resin, or by spraying the thermally conductive liquid-phase rubber or resin onto the outer surface of the main body and then curing the thermally conductive liquid-phase rubber or resin.

4. The heat transfer device of claim 1, wherein the heat transfer device is a heat pipe, a heat spreader, or a vapor chamber.

5. The heat transfer device of claim 1, wherein the thermally conductive layer is electrically insulative.

6. The heat transfer device of claim 1, wherein the main body is inserted in an accommodation groove of a metal case such that a portion of the thermally conductive layer corresponding to a lower surface of the main body is brought into contact with a bottom of the accommodation groove and an upper surface of the main body is exposed for direct or indirect thermal contact with a heat source,

wherein an outer surface of the thermally conductive layer has self-adhesion such that the thermally conductive layer is adhered to the bottom of the accommodation groove.

7. The heat transfer device of claim 6, wherein portions of the thermally conductive layer corresponding to lateral sides of the main body are elastically brought into contact with both sidewalls of the accommodation groove.

8. The heat transfer device of claim 1, wherein the thermally conductive layer is a thermally conductive silicone rubber or a thermally conductive acrylic resin.

9. A heat transfer device comprising:

a main body formed of a metallic material and forming a tube sealed to maintain a vacuum therein;

a first thermally conductive layer having elasticity and a self-adhesive outer surface and adhered to a surface of the main body; and

a second thermally conductive layer having elasticity and a self-adhesive outer surface and adhered to an opposite surface of the main body.

10. The heat transfer device of claim 9, wherein the first thermally conductive layer has greater self-adhesion and less thermal conductivity than the second thermally conductive layer, and

the first thermally conductive layer is brought into contact with a cooling case, and the second thermally conductive layer is brought into contact with a heat source.

11. A heat transfer device comprising:

a thermally conductive layer having elasticity and flexibility and adhered around the main body; and

a thermally conductive particle layer formed of thermally conductive particles attached to an outer surface of the thermally conductive layer.

12. The heat transfer device of claim 11, wherein the thermally conductive particles are metal powder, carbon powder, ceramic powder, graphite power, or carbon fiber having high thermal conductivity.