Vapor Chamber and Capillary Film Thereof

Abstract

A vapor chamber includes a casing, a working liquid, and a capillary film. The casing includes a heat-absorbing sheet and a heat-releasing sheet opposite to the heat-absorbing sheet. The casing includes a sealed space therein. The working liquid is filled in the sealed space. The capillary film is received in the sealed space and contacts the working liquid. The capillary film is produced from sintering a mixture including thermally conductive particles of at least two different lengths.

Claims

1. A capillary film produced from sintering a mixture including thermally conductive particles of at least two different lengths.

2. The capillary film as claimed in claim 1, wherein the thermally conductive particles include longest thermally conductive particles and shortest thermally conductive particles, and wherein the longest thermally conductive particles have a length 5-25 times of a length of the shortest thermally conductive particles.

3. The capillary film as claimed in claim 1, wherein the thermally conductive particles include longest thermally conductive particles and shortest thermally conductive particles, and wherein the longest thermally conductive particles have a length 10-20 times of a length of the shortest thermally conductive particles.

4. The capillary film as claimed in claim 1, wherein the mixture includes the thermally conductive particles having at least one material selected from copper, copper alloy, aluminum, and aluminum alloy.

5. The capillary film as claimed in claim 1, wherein the mixture includes the thermally conductive particles having metal particles and graphite particles.

6. The capillary film as claimed in claim 1, wherein the thermally conductive particles include different materials.

7. The capillary film as claimed in claim 1, wherein the capillary film has a thickness of 0.05-0.5 mm.

8. The capillary film as claimed in claim 7, wherein the capillary film has a thickness of 0.2-0.4 mm.

9. The capillary film as claimed in claim 1, wherein the capillary film includes a first layer and a second layer disposed on a top of the first layer, wherein each of the first layer and the second layer is comprised of the thermally conductive particles of at least two different lengths, and wherein a density of the first layer is larger than a density of the second layer.

10. A vapor chamber comprising: a casing including a heat-absorbing sheet and a heat-releasing sheet opposite to the heat-absorbing sheet, wherein the casing includes a sealed space therein; a working liquid filled in the sealed space; and a capillary film set forth in claim 1, wherein the capillary film is received in the sealed space and contacts the working liquid.

11. The vapor chamber as claimed in claim 10, wherein the casing includes at least one supporting post located in the sealed space, wherein the capillary film has at least one through-hole, wherein the at least one supporting post extends through the at least one through-hole, and wherein the at least one supporting post has two ends connected to the heat-absorbing sheet and the heat-releasing sheet, respectively.

12. The vapor chamber as claimed in claim 11, wherein the at least one supporting post is integrally formed with or coupled to the heat-releasing sheet, wherein at least one positioning stub is integrally formed with or coupled to the heat-absorbing sheet and has a recess, wherein the at least one positioning stub is received in the at least one through-hole of the capillary film, and wherein the at least one supporting post extends into the recess of the at least one positioning stub.

13. The vapor chamber as claimed in claim 12, wherein the at least one positioning stub has a non-circular outer periphery.

14. The vapor chamber as claimed in claim 10, wherein each of the heat-absorbing sheet and the heat-releasing sheet includes a sink formed by etching, wherein each sink has an annular wall disposed therearound, wherein the annular wall of the heat-absorbing sheet and the annular wall of the heat-releasing sheet contact each other, and the two annular walls are coupled by laser welding around contacted portions thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 is an exploded, perspective view of a vapor chamber of an embodiment according to the present invention.

[0028] FIG. 2 is a partial, cross sectional view of the vapor chamber of the embodiment according to the present invention.

[0029] FIG. 3 is a perspective view of a capillary film of the vapor chamber of the embodiment according to the present invention.

[0030] FIG. 4 is a cross sectional view of a capillary film of another embodiment according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0031] With reference to FIGS. 1 and 2, a vapor chamber of an embodiment according to the present invention includes a casing 1 and a capillary film 2 The capillary film 2 is received in the casing 1.

[0032] The casing 1 includes a heat-absorbing sheet 1a and a heat-releasing sheet 1b opposite to the heat-absorbing sheet 1a. The casing 1 includes a sealed space S therein. The sealed space S is filled with a working liquid (not shown) and receives the capillary film 2 The sealed space S is preferably in a vacuum state. The working liquid can be pure water, ethanol, etc. The working liquid will not fill the whole sealed space S when in a liquid state.

[0033] Specifically, the heat-absorbing sheet 1a and the heat-releasing sheet 1b can be made of copper, aluminum, or other material having a high coefficient of thermal conduction. At least one of the heat-absorbing sheet 1a and the heat-releasing sheet 1b may have a sink 11, such that the above-mentioned sealed space S is formed between the heat-absorbing sheet 1a and the heat-releasing sheet 1b after coupling. For example, but not limited hereto, an etching process may be adopted in this embodiment to form a sink 11 in each of two mutually facing faces of the heat-absorbing sheet 1a and the heat-releasing sheet 1b. Furthermore, each sink 11 has an annular wall 12 disposed therearound, such that the heat-releasing sheet 1b can be placed into the sink 11 of the heat-absorbing sheet 1a. Furthermore, the two annular walls 12 can be coupled by laser welding around contacted portions thereof to form the sealed space S from the sink 11 of the heat-releasing sheet 1a. The angle θ of proceeding the laser welding is preferably 30°-75° to the horizontal plane, increasing the operational convenience of laser welding. In another embodiment, a reverse arrangement can be made. Namely, the heat-absorbing sheet 1a is placed into the sink 11 of the heat-releasing sheet 1b, and the sealed space S is formed from the sink 11 of the heat-receiving sheet 1a. Alternatively, the annular wall 12 of the heat-absorbing sheet 1a and the annular wall 12 of the heat-releasing sheet 1b are superimposed to form the sealed space S from both sinks 11. Other equivalent structures can also be provided. Thus, the casing 1 is not limited to the structure illustrated in the figures of this embodiment.

[0034] Furthermore, the casing 1 can include at least one supporting post 13 located in the sealed space S. The at least one supporting post 13 has two ends connected to the heat-absorbing sheet 1a and the heat-releasing sheet 1b, respectively. The at least one supporting post 13 can support portions of the heat-absorbing sheet 1a and the heat-releasing sheet 1b within the annular walls 12 to reduce the deformation of the casing 1. In this embodiment, the at least one supporting post 13 can be integrally formed with or coupled to the heat-releasing sheet 1b. The casing 1 can further include at least one positioning stub 14. The at least one positioning stub 14 can be integrally formed with or coupled to the heat-absorbing sheet 1a and has a recess 15 through which the at least one supporting post 13 extends to couple. Preferably, the at least one positioning stub 14 can have a non-circular outer periphery.

[0035] With reference to FIGS. 2 and 3, the capillary film 2 is received in the sealed space S and contacts the working liquid. The capillary film 2 is a porous sheet produced from sintering a mixture. The capillary film 2 is relatively thin and has a thickness of about only 0.05-0.5 mm, preferably 0.2-0.4 mm. For example, powder metallurgy, such as sintering, can be carried out on the mixture, and the sintered powders can undergo pressing, flattening, etc. to obtain the capillary film 2 of the desired thickness, shape, or proper size. Furthermore, during the pressing and flattening procedures, grooves can be formed on the capillary film 2 at the same time to increase the flow guiding capability of the capillary film 2.

[0036] The mixture includes thermally conductive particles of at least two different lengths. In the present invention, “thermally conductive particles of a certain length” means a group of thermally conductive particles and, among which, each thermally conductive particle has a length close to an average length of the group of thermally conductive particles, ignoring manufacturing tolerance. Thus, the porous film formed by sintering has a better structural strength and is less likely to break. For example, a length of the longest thermally conductive particles is about 5-25 (preferably about 10-20) times of a length of the shortest thermally conductive particles. After sintering, relatively longer thermally conductive particles can link with each other like fibers to increase the bonding strength between the thermally conductive particles. Furthermore, the shortest thermally conductive particles can be approximately ball-shaped and can have a diameter of about 1-25 μm. The shapes of the thermally conductive particles of different lengths can be identical or different. The present invention is not limited in this regard. The shape for a thermally conductive particle is defined by the cross-sectional shape perpendicular to a long axis of the thermally conductive particle.

[0037] The mixture can mainly include thermally conductive particles having at least one material selected from copper, copper alloy, aluminum, and aluminum alloy. Thus, the capillary film 2 can have an excellent thermally conductive effect. Namely, the longest thermally conductive particles and the shortest thermally conductive particles can be an identical material or different materials. The present invention is not limited in this regard. For example, in a case that the cooling demand is not too high, thermally conductive particles with lower costs can be mixed to effectively reduce the material cost of the capillary film 2 Furthermore, the mixture does not have to be totally comprised of thermally conductive particles being metal but can also include non-metal thermally conductive particles, such as thermally conductive particles being graphite. Namely, the thermally conductive particles can have both graphite particles and metal particles, which include at least one material selected from copper, copper alloy, aluminum, and aluminum alloy, thereby increasing the thermal conduction effect of the capillary film 2 produced from sintering.

[0038] In the embodiment in which the casing 1 includes at least one supporting post 13 and at least one positioning stub 14, the capillary film 2 can have at least one through-hole 21. The at least one positioning stub 14 is fitted in the at least one through-hole 21 of the capillary film 2 to prevent rotation of the capillary film 2 relative to the heat-absorbing sheet 1a. Then, the heat-absorbing sheet 1a is coupled to the heat-releasing sheet 1b with the at least one supporting post 13 extending into the recess 15 of the at least one positioning stub 14. Thus, the heat-absorbing sheet 1a and the heat-releasing sheet 1b can be accurately aligned. Next, spot welding is carried out to weld the at least one supporting post 13 to the heat-absorbing sheet 1a.

[0039] With reference to FIGS. 1 and 2 again, the vapor chamber according to the present invention can be effectively thinned through the above structure. Furthermore, when using the vapor chamber, the heat-absorbing sheet 1a of the casing 1 can contact the heat source to absorb the heat energy. The heat energy heats the working liquid in the sealed space S, such that the working liquid can absorb the heat energy and vaporize into gaseous state. The vaporized working liquid condenses into the liquid state when contacting with the heat-releasing sheet 1b of a relatively lower temperature. Thus, the working liquid can continuously proceed with the cycle of phase change between the liquid state and the gaseous state by the capillary phenomenon of the capillary film 2 to carry away the heat energy of the heat source, thereby achieving effective cooling effect for the heat source.

[0040] With reference to FIG. 4, it is worth noting that the capillary film 2 can include a first layer 2a and a second layer 2b disposed on top of the first layer 2a, such that the first layer 2a is more adjacent to the heat-absorbing sheet 1a than the second layer 2b. Each of the first layer 2a and the second layer 2b is comprised of the thermally conductive particles of at least two different lengths. The first layer 2a and the second layer 2b can have different densities. Preferably, the density of the first layer 2a is larger than the density of the second layer 2b. In a non-limiting example, the number of the relatively shorter thermally conductive particles in the first layer 2a can be larger than the number of the relatively longer thermally conductive particles in the first layer 2a, and the number of the relatively longer thermally conductive particles in the second layer 2b can be larger than the number of the relatively shorter thermally conductive particles in the second layer 2b, such that the density of the first layer 2a can be larger than the density of the second layer 2b. Thus, the first layer 2a can provide a better capillary function for the working liquid, assisting in upward flow and vaporization of the working liquid. The second layer 2b can have more pores to increase the flowing capability of the vaporized working liquid, which is helpful in smooth condensation into the liquid state, thereby further increasing the cooling efficiency of the vapor chamber in a whole.

[0041] In view of the forgoing, in the vapor chamber and its capillary film according to the present invention, thermally conductive particles of at least two different lengths are sintered to form the capillary film 2, such that the relatively longer thermally conductive particles can link with each other like fibers after sintering to thereby increase the bonding strength between the thermally conductive particles. Thus, even though the thickness of the capillary film 2 is reduced to an extreme size smaller than 0.5 mm, the capillary film 2 can still have an excellent structural strength and is, thus, less likely to break, which is advantageous to development of thinning of the vapor chamber.

[0042] Thus since the invention disclosed herein may be embodied in other specific forms without departing from the spirit or general characteristics thereof, some of which forms have been indicated, the embodiments described herein are to be considered in all respects illustrative and not restrictive. The scope of the invention is to be indicated by the appended claims, rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.