Vapor chamber for dissipation heat generated by electronic component

A vapor chamber includes a base (100) for contacting a heat-generating component (500), a cover (200), a first porous capillary sheet (300) located in the base and a second porous capillary sheet (400) located in the cover and facing the first porous capillary sheet. The base comprises a block (130) extending from the base to thermally connect with the cover. The cover is mounted on the base and forms a hermetically sealed container together with the base. The first and second porous capillary sheets together form an enclosure and are contained in the container, and the block extends through the first and second porous capillary sheets and engage therewith.

FIELD OF THE INVENTION

The present invention relates to a vapor chamber, and more particularly to a plate type vapor chamber for cooling an electronic part such as a semiconductor or the like mounted on a circuit board, wherein heat can be rapidly transmitted from a portion of a base of the vapor chamber in contact with the electronic part to other portions of the vapor chamber.

DESCRIPTION OF RELATED ART

As computer technology continues to advance, electronic components such as central processing units (CPUs) of computers are made to provide faster operational speeds and greater functional capabilities. When a CPU operates at a high speed in a computer enclosure, its temperature usually increases enormously. It is desirable to dissipate the generated heat of the CPU quickly.

Conventionally, a plate type vapor chamber is used to dissipate heat generated by a CPU. Referring toFIG. 10, a conventional plate type vapor chamber comprises a hermetically sealed container10having a quantity of water enclosed therein. The container10comprises a base12for contacting a heat-generating component such as a CPU, and a cover14facing the base12. A plurality of fins20is attached to the cover14of the flat type vapor chamber. In use, heat produced by the CPU is conducted to the base12and evaporates the water into a vapor. The vapor flows towards the cover14and dissipates the heat thereto, then condenses into water and returns back to the base12for another circulation. The heat transferred to the cover14is radiated by the fins20to surrounding air.

The conventional plate type vapor chamber dissipates the heat produced by the CPU as latent heat. This avails the vapor chamber to dissipate a large quantity of heat with a small size. In use, only a central portion of the base12contacts the CPU; the central portion has a higher temperature than that of the other portions. If the water can not be timely supplied to the central portion of the base12, an overheat (or called dry-out) of the vapor chamber may occur. When the dry-out happens, the heat of the base12can be transferred to the cover14only through side walls of the container10of the vapor chamber. The heat transfer capability of the side walls of the container10by conduction is relatively low, in comparison with the phase change of the water in the vapor chamber. The dry-out problem degrades the heat transferring efficiency, and limits the use of the conventional plate type vapor chamber, even damages the conventional plate type vapor chamber.

What is needed, therefore, is a vapor chamber, which has a better heat dissipation efficiency.

SUMMARY OF INVENTION

A vapor chamber comprises a base for contacting a heat-generating component, a cover, a first porous capillary sheet located in the base and a second porous capillary sheet located in the cover and facing the first porous capillary sheet. The base comprises a block extending therefrom towards a direction away from the heat-generating component. The cover is mounted on the base and forms a hermetically sealed container together with the base. The block thermally contacts with both the base and cover. Furthermore, the block is located just above a portion of the base for contacting with the heat-generating component. The first and second porous capillary sheets together form an enclosure contained in the container, and the block extends through the first and second porous capillary sheets and contacts therewith.

DETAILED DESCRIPTION

Referring toFIGS. 1-4, a vapor chamber in accordance with a first preferred embodiment of the invention comprises a base100, a cover200sealed to the base100around their peripheral flanges120,220, and a first and a second porous capillary sheets300,400tightly attached to the facing surfaces of the base100and the cover200, respectively. An appropriate quantity of liquid such as water (not shown) is also placed within the vapor chamber to act as a heat transfer liquid. The quantity of the liquid to be used can be easily determined by those skilled in the art of vapor chamber. The first and second porous capillary sheets300,400have a plurality of pores, which have a capillary function, and move the water by surface tension. The water is guided by the first and second porous capillary sheets300,400to be uniformly and quickly spread at the base100. The first and second porous capillary sheets300,400, according to the preferred embodiment, are made of metal powders such as copper powders via sintering. It can be understood that the sheets300,400can be made by other methods, such as weaving of metal wires. For the sintering, the metal powders can be directly sintered on the facing surfaces of the base100and the cover200to form the first and second porous capillary sheets300,400, respectively.

The base100has a rectangular bottom110for contacting a CPU500mounted on a printed circuit board600(shown inFIG.5), and the four flanges120extend perpendicularly upwardly from four sides of the bottom110, respectively. According to the invention, it is a central portion of a bottom face (not labeled) of the bottom110of the base100that is brought to contact with the CPU500. A block130extends upwardly from a central portion of a top face (not labeled) of the bottom110of the base100. Accordingly, the CPU500is engaged with the base100under the block130. The block130is made of heat conductive material such as cooper or aluminum, and used for conducting heat from the base100to the cover200. The base100and the cover200are also made of heat conductive material such as copper or aluminum. An annular space (not labeled) is formed in the base100around the block130for receiving the first porous capillary sheet300.

The first porous capillary sheet300comprises a bottom wall310with a rectangular configuration, and four outer walls320extending upwardly from four sides of the bottom wall310, respectively. A rectangular hole330is defined through a center portion of the bottom wall310for the block130of the base100to extend therethrough. Four inner walls340extend upwardly from four edges of the rectangular hole330. A plurality of ribs350extends radially and outwardly from an outer periphery of the inner walls340towards the outer walls320. The ribs350divide the annulus space of the base100into several parts.FIG. 3shows that the first porous capillary sheet300is on the base100, in which the bottom wall310and the outer walls320of the first porous capillary sheet300engage with the bottom110and the flanges120of the base100, respectively. The inner walls340of the first porous capillary sheet300tightly surround an outer periphery of the block130simultaneously.

Referring also toFIG. 4, the cover200is used for covering the base100to form a hermetically sealed container. The cover200has a rectangular board210, and four flanges220extending perpendicularly downwards from four sides of the board210. Therefore, a recessed space is formed in the cover200for receiving the second porous capillary sheet400. The second porous capillary sheet400is a plate having an opening410defined therein. The opening410is aligned with the hole330of the first porous capillary sheet300for receiving the block130of the base100. When the second porous capillary sheet400is on the cover200, a depression230is formed in a center portion of the cover200for accommodating a top end of the block130.

FIG. 5shows a cross-sectional view of the vapor chamber in accordance with the first preferred embodiment of the present invention. The cover200together with the second porous capillary sheet400is sealed to the base100around their peripheral flanges120,220to form a hermetically sealed container. Therefore, the first and second porous capillary sheets300,400are enclosed in the container, and the first and second porous capillary sheets300,400form an enclosure contained in the container, simultaneously. The ribs350divide the enclosure into several small enclosed spaces for accommodating vapor of the water. The enclosure is tightly against the container. Thus, when the vapor condenses into water, the water can be quickly and uniformly guided back to the base100and the block130for another circulation. The enclosure together with the ribs350can accelerate the water returning back to wet the base100and the block130to improve the heat dissipation efficiency of the vapor chamber.

The block130of the base100extends through the rectangular hole330of the first porous capillary sheet300and the opening410of the second porous capillary sheet400, and contacts the cover200. Therefore, the block130can directly conduct heat from the base100to the cover200. The inner walls340and the second porous capillary sheet400tightly contact with the outer surface of the block130to keep the outer surface of the block130wet. Thus, the block130can be always supplied with liquid to prevent the dry-out problem confronted in the prior art vapor chamber.

FIGS. 6-9show another vapor chamber in accordance with a second preferred embodiment of the present invention. The main difference between the second and first embodiments is that a rectangular opening220is defined through the cover200′. The opening220of the cover200′ is aligned with the opening330of the first porous capillary sheet300and the rectangular hole410of the second porous capillary sheet400for receiving the block130of the base100. The block130of the base100extends through the rectangular hole330of the first porous capillary sheet300, the opening410of the second porous capillary sheet400and the rectangular opening220of the cover200′ in turn. An upper surface1302of the block130of the base100and an upper surface230of the cover200′ are positioned in a same plane.

In operation of the vapor chamber of the preferred embodiments of the invention, the heat generated by the CPU500is absorbed by the base100. A part of the heat absorbed by the base100is directly transferred to the cover200(200′) via the block130of the base100by means of heat conduction of metal. According to the invention, the block130thermally engages with the cover200(200′). The other part of the heat absorbed by the base100evaporates the water in the vapor chamber into a vapor. The vapor flows towards the cover200(200′), dissipates the heat thereto, and then is condensed into water and returns back to the base100for another circulation. Therefore, the other part of the heat absorbed by the base100is transferred to the cover200(200′) by means of phase change of fluid. At last, the cover200(200′) dissipates the heat to surrounding air.

The block130of the base100can quickly conduct the heat from the base100to the cover200(200′), whereby the heat absorbed by the base100from the CPU can be more evenly and quickly distributed to whole vapor chamber. Therefore, the dry-out problem of the vapor chamber can be mitigated, and the reliability and heat dissipation efficiency of the vapor chamber are improved.

It can be understood that a plurality of fins (not shown) may be attached to the cover200(200′) to further improve the heat dissipation of the vapor chamber.