JP4676090B2 - Plate heat pipe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plate heat pipe used for cooling an electronic device.
[0002]
[Prior art]
One means for efficiently dissipating heat from the semiconductor chips of electronic equipment, which are increasing year by year, is a heat pipe. In particular, among heat pipes, plate heat pipes have attracted attention in terms of securing a heat receiving surface with respect to the chip surface and heat diffusion.
[0003]
The heat pipe is composed of a hollow container (container), the inside of the container is depressurized and in a vacuum state, and an appropriate amount of liquid is sealed as a working fluid therein. When heat is received from a certain location outside the container, the liquid present in the portion where the heat is received evaporates and absorbs latent heat of vaporization there. The vapor fills the container due to the pressure difference, condenses on the inner surface of the container other than the heat receiving portion, and releases latent heat of vaporization there. The condensed liquid returns to the evaporation unit by a liquid reflux mechanism called a wick made of a mesh, a wire, and the like previously provided on the inner tube wall, and again evaporates at the heat receiving unit. The circulation described above is repeated, and as a result, there is an effect that heat is diffused throughout the container.
[0004]
In the case of a plate-type heat pipe, in particular, when the chip area as a heat generating element thermally connected to the heat pipe is small, the area of the evaporation portion corresponding to the chip area in the heat pipe becomes small, and the heat flow Since the bundle becomes large, there is a high possibility that a so-called dry out in which no working fluid is present occurs. Further, the chip itself does not generate heat uniformly over the entire surface, and the possibility of local dryout increases. In order to solve such problems, it has been proposed to arrange a metal block at a position on the inner surface corresponding to a position in contact with the tip of the plate heat pipe.
[0005]
FIG. 5 is a view showing a cross section of a plate-type heat pipe provided with a metal block. As shown in FIG. 5, the plate heat pipe 20 includes a sealed container formed by an upper plate member 21 and a lower plate member 22, and includes a metal block 23 at a position corresponding to the position of the heating element in the container. ing. The metal block has a quadrangular prism shape, and is joined to the upper plate material and the lower plate material of the container on the upper surface and the lower surface, respectively. The metal block has a cross section of the same size.
[0006]
In the plate heat pipe 20 provided with the metal block 23, first, heat transmitted through the material of the lower plate material 22 of the container to which the chip is connected is received by the metal block 23 joined to the inner surface of the container. Then, after being soaked to some extent, it is formed by a block side surface 24 around the metal block and neighboring surfaces 25 and 26 in contact with the metal block on the inner wall of the container, which are indicated by diagonal lines in FIG. It is considered that the portion that functions as a whole functions as an evaporation section, and as a result, no dryout occurs.
[0007]
However, if the integration density of the chip is dramatically increased, the amount of heat generation is further increased, and the thickness of the plate heat pipe cannot be sufficiently taken into account due to the surrounding equipment, the heat is further increased. Pipes are subjected to severe operating conditions. For example, in the case where the thickness of the inside of the plate heat pipe is 2 mm or less, even if the metal block as described above is provided in the heat pipe, the height of the block is limited and the size of the side surface of the block is also reduced. Due to the limitation, it becomes impossible to secure an evaporation portion having a sufficient area as in the conventional case.
[0008]
[Problems to be solved by the invention]
As described above, when the degree of chip integration is dramatically increased and the amount of heat generated from the chip is increased accordingly, in the conventional plate heat pipe, in the portion in the container corresponding to the position where the chip is connected, A so-called dryout in which no working fluid is present occurs, and the chip cannot be sufficiently cooled. In order to solve the problem, a plate type heat pipe having a sealed container formed of an upper plate material and a lower plate material and having a metal block at a position corresponding to the position of the heating element in the container is proposed. However, when the integration density of the chip is dramatically increased, the amount of heat generated from the chip is increased, and when the thickness of the plate heat pipe is limited, a metal block is provided in the heat pipe. However, the height of the block and the size of the side surface are limited accordingly, and there is a possibility that an evaporation part having a sufficient area cannot be secured.
[0009]
Accordingly, an object of the present invention is to provide a plate heat pipe that can efficiently cool a semiconductor chip or the like of an electronic device whose heat generation density increases dramatically even if the thickness thereof is limited. .
[0010]
[Means for Solving the Problems]
In order to solve the above-mentioned conventional problems, the inventors have conducted extensive research. As a result, even if the thickness of the heat pipe is limited, for example, by changing the cross-sectional area at the bottom and top surface of the metal block installed inside the plate heat pipe and expanding the evaporation part, It has been found that semiconductor chips and the like can be efficiently cooled without causing dryout.
[0011]
The present invention has been made on the basis of the above-described knowledge and the like, and the invention of claim 1 is directed to heat conduction in which a heat generating element is thermally connected to an upper plate made of a thin plate of a heat conductive member and a part thereof. A container formed of a lower plate made of a thin plate of a conductive member and having a cavity portion that is hermetically depressurized, a thermally conductive block disposed at a position in the container corresponding to the position of the heating element, and the container In the plate-type heat pipe having a contained working fluid, the thermally conductive block defines an arc with a predetermined curvature from one plate member to which the heat generating element is thermally connected toward the other plate member. And has a partial spherical shape that is elongated, and the peripheral surface of the partial spherical shape is an evaporation surface.
[0012]
The invention of claim 2 is formed by an upper plate made of a thin plate of a heat conductive member and a lower plate made of a thin plate of a heat conductive member provided with a block portion to which a heat generating element is thermally connected. In a plate heat pipe comprising a container having a hollow portion formed therein and a working fluid accommodated in the container, the block portion has an arc with a predetermined curvature from the lower plate material toward the upper plate material. It consists of a partially spherical shape drawn and stretched, and the peripheral surface of the partially spherical surface is an evaporation surface.
[0016]
The invention of claim 3 is the invention of claim 1 or 2, before Kinetsu conductive block or the block unit is characterized in that it consists of sintered metal.
[0017]
The invention of claim 4 is the invention according to any one of claims 1 to 3, further comprising a wick accommodated in the container .
[0018]
Another aspect of the plate heat pipe of the present invention is a plate heat pipe characterized in that the container and the metal block or the block are made of copper, and the working fluid is water.
[0019]
Another aspect of the plate-type heat pipe of the present invention is a plate-type heat pipe, wherein the metal block is joined to the upper plate material and the lower plate material by brazing.
Another aspect of the plate-type heat pipe of the present invention is a plate-type heat pipe, wherein the metal block is mechanically joined to the upper plate material and the lower plate material.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described with reference to the drawings.
One aspect of the plate-type heat pipe of the present invention is as follows: (1) an upper plate made of a thin plate of a heat conductive member (for example, a metal having a hollow portion formed in the central portion), and a heating element in a part thereof A container having a hollow portion formed of a thin plate of a thermally conductive member (for example, a flat metal) to be thermally connected, and (2) corresponding to the position of the heating element. A plate-type heat pipe provided with a thermally conductive (for example, metal) block having an enlarged evaporation surface and disposed at a position in the container, and (3) a working fluid contained in the container It is.
[0021]
The enlarged evaporation surface described above is formed by the difference in the area of the cross section on the heat receiving part side of the metal block and the area of the cross section on the opposite side to the heat receiving part side. Further, the enlarged evaporation surface described above may be formed by the metal block having a truncated pyramid shape or a truncated cone shape. Furthermore, the enlarged evaporation surface described above may be formed by the metal block being partially spherical. Further, the enlarged evaporation surface described above may be formed by the metal block made of sintered metal. In addition, a wick may be accommodated in the container mentioned above. It is preferable that the container mentioned above and a metal block or the block mentioned later are copper, and a working fluid is water.
[0022]
These aspects will be described in more detail with reference to the drawings. FIG. 1 is a view showing a cross section of one embodiment of a plate heat pipe of the present invention. As shown in FIG. 1, a plate-type heat pipe 10 is formed by an upper plate 1 made of a metal thin plate having a hollow portion formed in the center and a lower plate 2 made of a flat metal thin plate, and is sealed and depressurized. A container having a hollow portion 9 is provided, and between the upper plate member 1 and the lower plate member 2, a truncated pyramid-shaped metal block is joined to the inner wall of the upper plate member and the inner wall of the lower plate member, respectively. As the upper plate material, for example, a rectangular copper plate is pressed to form a shape in which the central portion is recessed with respect to the rectangular outer peripheral portion.
[0023]
In the truncated pyramid-shaped metal block, the area of the cross section of the lower end portion in contact with the inner wall of the lower plate member is larger than the area of the cross section of the upper end portion in contact with the inner wall of the upper plate member. That is, since each side surface 5 of the metal block is inclined at a predetermined angle, the area of the side surface 5 is larger than the area of the side surface of the conventional prismatic metal block. Therefore, the evaporation portion formed by the side surface 5 of the metal block, the vicinity portion 7 in contact with the metal block on the inner wall of the upper plate member, and the vicinity portion 6 in contact with the metal block on the inner wall of the lower plate member is enlarged. ing. As a result, even if the thickness of the plate heat pipe is limited and thinned, the side of the metal block is inclined at a predetermined angle. The heating fluid is soaked by the manufacturing block and the working fluid located in the evaporation section is evaporated, thereby effectively cooling the heating element.
[0024]
Even when the metal block has a truncated cone shape, the metal block has a cross-sectional area of the lower end portion in contact with the inner wall of the lower plate member that is larger than an area of a cross section of the upper end portion in contact with the inner wall of the upper plate member. That is, since the side surface 5 of the metal block extends in an arc with a predetermined curvature from the lower plate material toward the upper plate material, the area of the side surface 5 is the same as that of the side surface of the conventional prismatic metal block. It is larger than the area. Therefore, the evaporation portion formed by the side surface 5 of the metal block, the vicinity portion 7 in contact with the metal block on the inner wall of the upper plate member, and the vicinity portion 6 in contact with the metal block on the inner wall of the lower plate member is enlarged. ing. As a result, even if the thickness of the plate heat pipe is limited and thinned, the side surface of the metal block is inclined with a predetermined curvature. The heating fluid is soaked by the manufacturing block and the working fluid located in the evaporation section is evaporated, thereby effectively cooling the heating element.
[0025]
FIG. 2 is a view showing a cross section of another embodiment of the plate heat pipe of the present invention. In the embodiment shown in FIG. 2, the metal block has a partial spherical shape. As shown in FIG. 2, even when the metal block is partially spherical, the metal block has a lower cross-sectional area in contact with the inner wall of the lower plate material than an upper cross-sectional area in contact with the inner wall of the upper plate material. Is also big. The upper part of the partial spherical shape does not necessarily need to contact the inner wall of the upper plate material. Since the side surface 8 of the metal block extends in an arc with a predetermined curvature from the lower plate material toward the upper plate material, the surface area of the side surface 8 is larger than the area of the side surface of the conventional prismatic metal block. It has become.
[0026]
Therefore, the evaporation portion formed by the side surface 8 of the metal block, the vicinity 11 of the metal block on the inner wall of the upper plate member, and the vicinity 12 in contact with the metal block of the inner wall of the lower plate member is enlarged. As a result, even if the thickness of the plate heat pipe is limited and thinned, the side surface of the metal block is inclined with a predetermined curvature. The heating fluid is soaked by the manufacturing block and the working fluid located in the evaporation section is evaporated, thereby effectively cooling the heating element.
[0027]
FIG. 3 is a view showing a cross section of another embodiment of the plate heat pipe of the present invention. In the embodiment shown in FIG. 3, the metal block is made of sintered metal. As shown in FIG. 3, the metal block is made of sintered metal, so that the surface area of the metal block is relatively enlarged. Furthermore, when a metal block made of a pyramidal frustum-shaped, frustum-shaped, or partially spherical sintered metal is used, as the surface area is increased by the material, the truncated pyramid-shaped, frustum-shaped, or partially spherical shape is further described. In addition, in the metal block, the area of the cross section of the lower end portion in contact with the inner wall of the lower plate member is larger than the area of the cross section of the upper end portion in contact with the inner wall of the upper plate member. Since the side surface 8 of the metal block is inclined at a predetermined angle from the lower plate material toward the upper plate material or extends in an arc with a predetermined curvature, the surface area of the side surface 8 is a conventional prismatic shape. The area of the side of the metal block is larger.
[0028]
Therefore, in addition to the increase in the surface area due to the sintered metal, the side surface 8 of the metal block, the vicinity 11 of the metal block on the inner wall of the upper plate, and the vicinity 12 in contact with the metal block on the inner wall of the lower plate The evaporation part to be formed is enlarged. As a result, even if the thickness of the plate heat pipe is limited and thinned, the side surface of the metal block is inclined at a predetermined angle or curvature, so that it is transmitted from the heating element by the enlarged evaporation section. The generated heat is soaked by the metal block, and the working fluid located in the evaporating portion is evaporated, thereby effectively cooling the heating element. By using a metal block made of sintered metal, the evaporation section can be always kept wet without using another wick depending on the operation mode.
[0029]
Further, another aspect of the plate heat pipe of the present invention is (1) the opposite of the upper plate member made of a thin metal plate having a recess in the center and the surface to which the heating element is thermally connected. A container having a cavity portion formed by a lower plate member made of a metal thin plate having a block portion having an enlarged evaporation surface, which is integrally formed on the side surface, and having a hermetically evacuated cavity portion; (2) It is the plate-type heat pipe provided with the working fluid accommodated in a container.
[0030]
The expanded evaporation surface mentioned above may be formed by the area of the cross section by the side of the heat receiving part of a block part differing from the area of the cross section by the side opposite to the heat receiving part side. Further, the enlarged evaporation surface described above may be formed by the block portion having a truncated pyramid shape or a truncated cone shape. Furthermore, the enlarged evaporation surface mentioned above may be formed by the block part being a partial spherical shape. Furthermore, the enlarged evaporation surface described above may be formed by the block portion being made of sintered metal.
[0031]
These aspects will be described in more detail with reference to the drawings.
FIG. 4 is a view showing a cross section of another embodiment of the plate heat pipe of the present invention. As shown in FIG. 4, the plate heat pipe 10 includes an upper plate 1 made of a metal thin plate having a recessed portion formed in the center, and a surface opposite to the surface to which the heating elements are thermally connected. The container is provided with a container having a hollow part that is formed by a metal thin plate having a block part 3 having an enlarged evaporation surface and is formed of a metal plate, and is hermetically decompressed. Between the lower plate member and the lower plate member, a partially spherical block formed integrally with the lower plate member is joined to the inner wall of the upper plate member.
[0032]
As the upper plate material, for example, a rectangular copper plate is pressed to form a shape in which the central portion is recessed with respect to the rectangular outer peripheral portion. That is, in this aspect, the lower plate member 2 is provided with a block portion that is integrally formed on the surface opposite to the surface to which the heat generating elements are thermally connected. The block portion is formed by, for example, raising the meat by forging the lower plate material. Since the lower plate material and the block portion are integrally formed, the thermal resistance is small and the thermal conductivity is excellent. The block part mentioned above may be joined to the upper plate material by brazing, or may be mechanically joined.
[0033]
In the embodiment shown in FIG. 4, the block portion formed integrally with the lower plate material has a partial spherical shape. As shown in FIG. 4, since the block portion is partially spherical, the block portion has an upper end where the area of the cross section of the portion corresponding to the inner wall of the lower plate material is in contact with the inner wall of the upper plate material, as in the other embodiments described above. It is larger than the area of the cross section of the part. The upper part of the partial spherical shape does not necessarily need to contact the inner wall of the upper plate material. Since the side surface 8 of the block part extends from the lower plate material toward the upper plate while forming an arc with a predetermined curvature, the surface area of the side surface 8 is larger than the area of the side surface of the conventional prismatic metal block. ing.
[0034]
Accordingly, the evaporation portion formed by the side surface 8 of the block portion, the vicinity portion 11 of the metal block on the inner wall of the upper plate member, and the vicinity portion 12 adjacent to the block portion of the inner wall of the lower plate member is enlarged. As a result, even if the thickness of the plate heat pipe is limited and thinned, the side surface of the block portion is inclined with a predetermined curvature, so that the heat transmitted from the heating element by the enlarged evaporation portion is the lower plate material So as to cool the heat generating element effectively by evaporating the working fluid located in the evaporation portion.
[0035]
Although not shown in the drawings, the block portion formed integrally with the lower plate material is also used when the block portion is in the shape of a truncated pyramid or a truncated cone and when the block portion is made of sintered metal. In the same manner as described in the other aspects described above, each has an enlarged evaporation part, and in each case, the heat transmitted from the heating element is soaked and enlarged by the block part formed integrally with the lower plate material. The working fluid located in the evaporated portion is evaporated to effectively cool the heating element.
Also in this aspect, the wick may be accommodated in the container. The container and the block described above are preferably made of copper and the working fluid is water.
[0036]
According to the present invention, the non-uniform heat generated in the heating element is soaked to some extent by the metal block or block portion and transmitted to the heat pipe. At that time, if the metal block or block portion has a shape such as a truncated pyramid, a truncated cone, or a hemisphere, the surface functioning as the evaporation portion of the heat pipe increases, and a stable operation is ensured. This is particularly effective when the thickness of the plate heat pipe is limited.
Regarding the heat receiving side, it is important that the metal block is joined and integrated with the heat pipe container by brazing or the like. It is desirable that the metal block or the upper end portion of the block portion is also joined to the container by brazing or the like.
As described above, according to the present invention, it is possible to obtain a plate heat pipe capable of stably diffusing heat even with a higher heat load. The metal thin plate and the metal block described above are not limited to being made of metal, but may be made of a heat conductive member.
Further, the present invention will be described in detail by examples.
[0037]
【Example】
Example 1
According to one of the present invention, as shown in FIG. 1, in a copper plate having a thickness of 1 mm × width of 60 mm × length of 60 mm, a depression having a level difference of about 2 mm is formed by pressing at the central portion leaving the outer periphery of 3 mm. An upper plate 1 was prepared. Furthermore, the lower board | plate material 2 was prepared with the rectangular copper plate of thickness 1mm * width 60mm * length 60mm. The upper plate member 1 and the lower plate member 2 thus prepared are combined so that a space of 2 mm is formed, and a rectangular shape having a bottom surface of 10 mm × 10 mm and a top surface of 2 mm × 2 mm is formed between the two copper plates. The pyramidal pyramid-shaped copper block 3 having a height of 2 mm was sandwiched so as to be located in the center, and the two copper plates and the copper block were joined and integrated with a silver solder.
In addition to the copper block, a plurality of copper pillars 4 were sandwiched between two copper plates to reinforce the container, and these were also joined together by silver brazing and integrated. Using a sealing portion (not shown), vacuum injection was performed to prepare a heat pipe. Water was used as the working fluid. Furthermore, the heat pipe space was filled with a laminated mesh. In this way, a plate-type heat pipe having an outer shape of 4 mm × 60 mm × 60 mm was produced.
[0038]
According to the plate-type heat pipe of the present invention described above, the heat transport limit is increased by 100% compared to a conventional plate-type heat pipe in which a rectangular block of the same external shape and the same cross-sectional area is joined in a container. .
[0039]
Example 2
In accordance with one of the present invention, as shown in FIG. 4, in a copper plate having a thickness of 1 mm × width of 40 mm × length of 40 mm, a depression having a step of about 1.5 mm is formed by pressing at the central portion leaving the outer periphery of 3 mm. The upper board | plate material 1 was prepared by forming. Furthermore, a rectangular spherical copper plate having a thickness of 1 mm, a width of 40 mm, and a length of 40 mm is formed by forming a partial spherical block portion (swelling) 3 having a bottom surface 15φ and a height of 1.5 mm at the center by forging. Prepared. At this time, the copper pillar 4 was also formed at the same time. The upper plate member 1 and the lower plate member 2 thus prepared were combined so that a space of a gap of 1.5 mm was formed, and they were joined together by silver brazing.
Using a sealing portion (not shown), vacuum injection was performed to prepare a heat pipe. Water was used as the working fluid. Furthermore, the heat pipe space was filled with a laminated mesh. In this way, a plate heat pipe having an outer shape of 3.5 mm × 40 mm × 40 mm was produced.
[0040]
According to the plate-type heat pipe of the present invention described above, the heat transport limit is increased by 100% compared to a conventional plate-type heat pipe in which a rectangular block of the same external shape and the same cross-sectional area is joined in a container. .
[0041]
Example 3
In accordance with one of the present invention, as shown in FIG. 3, in a copper plate having a thickness of 1 mm × width of 40 mm × length of 40 mm, a depression having a step of about 1.5 mm is formed by pressing at the central portion leaving the outer periphery of 3 mm. Thus, an upper plate 1 was prepared. Furthermore, the lower board | plate material 2 was prepared with the rectangular copper plate of thickness 1mm * width 40mm * length 40mm. Further, a partially spherical sintered metal block 3 having a bottom surface 15φ and a height of 1.5 mm was joined to the center of the lower plate 2. The upper plate member 1 and the lower plate member 2 thus prepared were combined so that a space of a gap of 1.5 mm was formed, and they were joined together by silver brazing.
Using a sealing portion (not shown), vacuum injection was performed to prepare a heat pipe. Water was used as the working fluid. The amount of hydraulic fluid was 30-40%. No wick was used in the heat pipe space. In this way, a plate heat pipe having an outer shape of 3.5 mm × 40 mm × 40 mm was produced.
[0042]
According to the plate heat pipe of the present invention described above, the heat transport limit is increased by 70% compared to a conventional plate heat pipe in which a rectangular block of the same external shape and the same cross-sectional area is joined in a container. .
[0043]
【The invention's effect】
According to the present invention, there is provided a plate heat pipe capable of efficiently cooling a semiconductor chip or the like of an electronic device whose heat generation density increases dramatically even if the thickness of the plate heat pipe container is limited. be able to.
[Brief description of the drawings]
FIG. 1 is a view showing a cross section of one embodiment of a plate heat pipe of the present invention.
FIG. 2 is a view showing a cross section of another embodiment of the plate heat pipe of the present invention.
FIG. 3 is a view showing a cross section of another embodiment of the plate heat pipe of the present invention.
FIG. 4 is a view showing a cross section of another embodiment of the plate heat pipe of the present invention.
FIG. 5 is a view showing a cross section of a plate heat pipe provided with a conventional metal block.
[Explanation of symbols]
1 Upper plate material 2 Lower plate material 3 Metal block, Block portion 4 Copper pillar 5 Side surface 6 Near portion 7 Near portion 8 Surface 9 Cavity portion 10 Plate heat pipe 11 Near portion 12 Near portion 20 Plate heat pipe 21 Upper plate material 22 Below Plate material 23 Metal block 24 Side surface portion 25 Near portion 26 Near portion

Claims (4)

A container having a cavity portion formed by an upper plate member made of a thin plate of a heat conductive member and a lower plate member made of a thin plate of a heat conductive member to which a heating element is thermally connected to a part of the upper plate member; In a plate heat pipe comprising a heat conductive block disposed at a position in the container corresponding to a position of the heating element, and a working fluid accommodated in the container,
The thermally conductive block is formed of a partial sphere extending in an arc with a predetermined curvature from one plate member to which the heat generating element is thermally connected to the other plate member, and evaporates the peripheral surface of the partial sphere. A plate-type heat pipe characterized by having a surface. A container having a cavity portion formed by an upper plate member made of a thin plate of a heat conductive member and a lower plate member made of a thin plate of a heat conductive member provided with a block portion to which a heat generating element is thermally connected and hermetically reduced in pressure. And a plate-type heat pipe provided with a working fluid contained in the container,
The block-shaped heat pipe is characterized in that it has a partial spherical shape that extends from the lower plate material toward the upper plate material while drawing an arc with a predetermined curvature, and the peripheral surface of the partial spherical surface is an evaporation surface. . Plate-type heat pipe of claim 1 or 2 before Kinetsu conductive block or the block unit is characterized in that it consists of sintered metal. The plate-type heat pipe according to any one of claims 1 to 3, further comprising a wick accommodated in the container.

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