JPH11223479A - Planar heat pipe and cooling structure employing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure efficient cooling by providing a planar heat pipe with solid parts penetrating up to the opposite major surfaces thereof at a part corresponding to a component being cooled and bringing it into contact with the component with low thermal resistance. SOLUTION: A planar heat pipe 1 is provided with solid parts 120-122 penetrating up to the opposite major surfaces (upper and lower surfaces) thereof. The solid parts 120-122 are made of blocks of a pure material and a component to be cooled is brought into contact with the lower surface of the solid parts 120-122. The solid parts 120-122 are then jointed to upper and lower plates 10, 11 to form a hermetically sealed cavity 13. A metallic material or graphite excellent in thermal conductivity or a ceramic material, e.g. aluminum nitride, is employed as a material of the solid parts 120-122. Since the solid parts are provided at a part corresponding to a component being cooled while penetrating up to the opposite major surfaces, high dimensional accuracy can be ensured for the distance to an object to be cooled, i.e., a heating component thus realizing an excellent cooling performance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate-shaped heat pipe and a cooling structure for cooling a component to be cooled such as a semiconductor device using the same.

[0002]

2. Description of the Related Art Electronic components such as semiconductor elements mounted on various devices such as personal computers and electric / electronic devices such as power equipment generate heat to some extent by use thereof. Overheating of this type of component can reduce its performance and life, and its cooling is an important technical issue. As a method of cooling a heat-generating component (cooled component) requiring cooling, for example, a method of ventilating air in a device with a fan, a method of attaching a soaking body (cooling body) to the cooled component, and cooling the component are known. ing.

[0003] As a heat equalizing member to be attached to the heat-generating component, a metal material such as a carbon material or an aluminum material having a high thermal conductivity, and a ceramic material such as a carbon material or aluminum nitride having a high thermal conductivity is used. good. Alternatively, a plate-shaped heat pipe may be used instead of such a block.

FIG. 7 schematically shows an example of such a cooling structure. The plate-type heat pipe 5 is arranged to face the heat-generating component 52 mounted on the printed board 54. The heat-generating component 52 is in contact with the plate-type heat pipe 5. The plate heat pipe 5 receives the heat from the heat generating component 52 to cool the heat generating component 52.
In the example of this figure, a radiation fin 51 is further attached to the plate-type heat pipe 5 to further promote the release of heat from the plate-type heat pipe 5 to the outside. Reference numeral 53 in the drawing denotes a lead of the heat-generating component 52 (assuming a semiconductor chip or the like). Reference numerals 50 and 501 respectively denote a container and a cavity constituting the plate-type heat pipe 5. Illustration of the working fluid and the like in the driving unit 501 is omitted.

Here, the heat pipe will be briefly described. Generally, a heat pipe includes a container having a sealed cavity and a working fluid, and heat is transferred by a phase change and movement of the working fluid contained in the cavity. The inside of the cavity is evacuated so that a phase change of the working fluid easily occurs.

When heat is applied to a part of the container constituting the heat pipe, heat is transmitted to the working fluid in the cavity at that part (often called a heat absorbing side or a heat absorbing portion), and the working fluid is Evaporate. The vapor moves in the cavity, and if, for example, a fin is attached to a heat pipe, the vapor is cooled at that portion (often called a heat radiation side, a heat radiation portion) and returns to a liquid state again. Then, the working fluid that has returned to the liquid phase moves (recirculates) to the heat absorbing side again.
Heat is transferred by such phase transformation and movement of the working fluid.

[0007] In order to continuously maintain the recirculation of the working fluid, the heat absorbing side is usually arranged below the heat radiating side. This is because the working fluid that has returned to the liquid phase is thus returned by gravity. However, in the case of an electric or electronic device such as a notebook personal computer, the device may be greatly inclined or inverted depending on the use condition.
This may make it difficult to expect the working fluid to recirculate due to gravity.

Therefore, there is a case where a wick having a capillary action is installed inside the heat pipe (hollow portion). The wick may be a metal mesh, a metal wire, or a fine groove formed on the inner wall of the cavity.

As a material of the heat pipe container, an aluminum material, a copper material, and other stainless materials are often used. It is not necessary that the entire container be made of the same material. As the working fluid, other than water, alternative chlorofluorocarbon or alcohol is used.

[0010]

In order to realize efficient cooling, the cooling structure of the form shown in FIG. 7 requires a heat-generating component 52 (semiconductor element or the like) to be cooled and a plate-type heat pipe. It is important to make the contact between the substrate 5 and the substrate 5 less.

When a plurality of heat-generating components to be cooled are mounted, their heights are often different due to different types of heat-generating components. In such a case,
As shown in FIG. 7, the form in which they are brought into contact with one plate-type heat pipe 5 is not easy. Therefore, the present inventors have previously described a heating component 6 to be cooled as shown in FIG.
The inventors have invented a plate-type heat pipe 6 provided with a convex portion corresponding to the height of 2,620 and have applied for a patent. In FIG. 8, the height of the heat generating component 62 and the heat generating component 620 from the printed circuit board 64 are different. However, if such a plate-type heat pipe 6 is used, it is possible to suitably cope with the cooling of the plurality of heat generating components 62, which is very efficient. Further, a space such as a wiring is often required between the adjacent heat generating components 62. However, if a plate-type heat pipe 6 as shown in FIG. 8 is used, it is advantageous in terms of securing the space. 8, reference numerals 60 and 601 denote a container and a cavity, reference numeral 61 denotes a radiating fin, and reference numerals 63 and 64 denote a lead and a printed circuit board, respectively.

In any of the cooling structures of FIGS. 7 and 8 described above, in order to bring the heat-generating component to be cooled into contact with the plate-shaped heat pipe with low thermal resistance, for example, heat transfer grease, etc. However, it is necessary to improve the dimensional accuracy of these elements. Specifically, the heating component 52
Plate-shaped heat pipe 5 with respect to the height of
It is desired to improve the dimensional accuracy of 6, and the flatness of the contact surface. For example, in many cases, a high dimensional accuracy of 0.01 mm or less is required as the height of each convex portion of the plate-type heat pipe 6 in FIG.

By the way, from the viewpoint of thermal characteristics, it is desirable that the thickness of the containers 50 and 60 constituting the plate-shaped heat pipes 5 and 6 be thin. Since the size (width) of the printed circuit boards 54 and 64 is generally about several cm, the plate-shaped heat pipes 5 and 6 are often of substantially the same size. In the case of the heat pipes 5 and 6 having such a size, the thickness of the containers 50 and 60 of 1 mm or less is sufficient in terms of strength (when a copper material container is used). That is, the thicknesses of the containers 50 and 60 constituting the plate-type heat pipes 5 and 6 are usually thin.

However, when such thin containers 50, 60 are employed, it is not easy to realize high dimensional accuracy of the plate-type heat pipes 5, 6 as described above from the viewpoint of cost and the like. The reason for this is that if the material is thin, it is easy to deform in the first place, and it is not easy to avoid deformation due to heat or the like particularly in the work such as welding or brazing when assembling the containers 50 and 60. Also, when a thin-walled container uses a manufactured plate-type heat pipe, it tends to be deformed due to an increase in internal pressure due to evaporation of a working fluid inside the heat pipe.

[0015]

DISCLOSURE OF THE INVENTION The present inventors have developed a plate-shaped heat pipe and a cooling structure using the heat pipe, which are in practical contact with a heat-generating component to be cooled and have a small thermal resistance so that efficient cooling is practically realized. Was invented. That is, a plate-type heat pipe provided to face the substrate on which the component to be cooled is mounted,
A plate heat pipe is proposed in which a portion corresponding to the component to be cooled is provided with a solid portion penetrating to both main surfaces of the plate heat pipe. Therefore, a part of the outer surface of the solid part forms a part of both main surfaces. Further, the solid portion may protrude toward a surface facing the component to be cooled.

[0016] The solid portion may be the same member as one main surface portion of the plate-type heat pipe. Also,
In some cases, the hollow portion of the plate-type heat pipe is provided separately from the solid portion, that is, the solid portion does not form a part of the inner wall of the hollow portion.

As the cooling structure, the plate-shaped heat pipe is disposed as a component to be cooled, facing the printed circuit board on which the semiconductor element is mounted, and the semiconductor element is connected to the plate-shaped heat pipe. A form in which a heat sink is joined is proposed. Further, a fan for sending air to the heat sink may be provided.

[0018]

FIG. 1 shows a cross section of an example of a plate-type heat pipe according to the present invention. The plate-shaped heat pipe 1 is provided with solid portions 120 to 122 penetrating to both main surfaces (upper and lower surfaces in the figure). Solid part 1
Reference numerals 20 to 122 are composed of chunks of the Muku material. A heating component (not shown) to be cooled is brought into contact with the lower surface of the solid portions 120 to 122 in the drawing. At that time, it is optional to interpose heat transfer grease or the like.

The solid portions 120 to 122 and the upper plate 10,
The lower plate 11 is joined to form a cavity 13 sealed inside. A working fluid (not shown) is accommodated in the hollow portion 13. Although not shown, a wick or the like may be arranged in the cavity 13. The material of the solid portions 120 to 122 is not particularly limited, but a metal material having excellent thermal conductivity, a ceramic material such as graphite or aluminum nitride, or a composite material thereof may be appropriately used.

FIG. 2 shows a cross section of another example of the plate type heat pipe of the present invention. The plate heat pipe 2 is formed by joining a lower plate 21 to an upper plate 22 having solid portions 220 to 222 penetrating to both main surfaces (upper and lower surfaces in the drawing). The solid members 220 to 222 are masses of a material having excellent heat conductivity. By doing so, there is no need to separately prepare a solid member as compared with the example shown in FIG. 1, and an advantage in terms of cost, such as a reduction in the number of parts, can be expected. The solid portions 220 to 222 may form an integral part with the lower plate 21 instead of the upper plate 22. Reference numeral 23 in the figure denotes a hollow portion, in which a working fluid (not shown) is stored. This plate type heat pipe 2
Also, the heat-generating components to be cooled, not shown, are solid portions 220 to
Contact the lower surface of 222.

FIG. 3 is similar to the example shown in FIG. 1, but in the case of the plate type heat pipe 3 shown, solid portions 320 to 322 are shown.
Is not in contact with the cavity 33. That is, the solid members 320 to 322 do not constitute a part of the inner wall forming the cavity 33. Thus, the solid members 320 to 322 and the cavity 33
Of the upper plate 30 and the lower plate 31 and the solid member 320
There is an advantage in assembling such that the airtightness of the cavity 33 can be easily realized in the joining operation with the 〜322. Further, since there is no contact between the solid members 320 to 322 and the working fluid and therefore there is no influence, there is an advantage that the material selection of the solid members 320 to 322 is widened.

In the plate-type heat pipe of the present invention, since the solid member is provided in a portion corresponding to the component to be cooled so as to penetrate to both main surfaces thereof, the distance from the heat-generating component to be cooled, etc. , It is easy to achieve high dimensional accuracy. If this solid member is formed by forging or high-precision casting, the cost can be reduced. If very high dimensional accuracy is to be realized, cutting may be performed.

The cooling structure using the plate-type heat pipe of the present invention as described above, when cooling a semiconductor component mounted on a printed circuit board, the plate-type heat pipe is opposed to the printed circuit board. It is preferable that the semiconductor component is thermally connected to the plate-shaped heat pipe, and a heat sink is further joined to the plate-shaped heat pipe. It is also effective to attach a fan for blowing air to the heat sink, if necessary, to enhance the cooling performance.

[0024]

FIG. 4 is a schematic perspective view for explaining the assembling state of a plate type heat pipe according to an embodiment of the present invention. FIG. 5 (A) is a sectional view taken along lines AA ', BB' and CC of FIG. 'Cross section, Fig. 5
(A) is a sectional view of the plate-type heat pipe 4 after assembling them. Reference numerals 40 and 41 denote an upper plate and a lower plate, respectively, and reference numerals 420 and 421 denote solid portions. In this example, there are four solid portions 420 and one solid portion 421. The number, position, and size of these solid portions are arbitrary, and are determined in consideration of the heat-generating components to be cooled. Upper plate 4
The 0 and the lower plate 41 are provided with through portions into which the solid portions 420 and 421 are inserted.

Upper plate 40, lower plate 41, solid portions 420, 42
Each of the materials 1 is oxygen-free copper. Solid parts 420, 42
1 is formed by cutting, and the upper plate 40 and the lower plate 41 are formed by pressing a plate material. Upper plate 4
The plate-shaped heat pipe 4 was assembled by vacuum brazing the 0, the lower plate 41, and the solid portions 420 and 421 with a silver brazing (Bg-8). Although not shown, a metal mesh was arranged as a wick in the cavity. Further, the inside of the hollow portion of the plate-type heat pipe 4 was evacuated by vacuum, and a working fluid (pure water) of about 30% of its volume was stored and sealed (heat pipe processing).

As a comparative example, a plate-type heat pipe 45 was assembled as shown in FIG. In the plate-type heat pipe 45, the solid portions 440 and 441 do not penetrate both main surfaces of the plate-type heat pipe 45. Reference numeral 43 in the figure,
44 is an upper board and a lower board, respectively.

In the above-mentioned assembling process, the flatness of the contact surface with the heat-generating component (the surface indicated by a and b in FIGS. 5 and 6) is compared before the brazing operation, after the brazing operation, and after the heat pipe processing. did. The flatness of the contact surface on the surface plate (the surface a and the surface b are five each,
The height at 25 points (a 0 mm square shape) was measured with a height gauge, and the difference between the maximum value and the minimum value (referred to as Δh) was taken as the average value. Table 1 shows the results.

[0028]

[Table 1]

As is clear from the results in Table 1, in the case of the plate type heat pipe 4 of the present invention, not only after the brazing step but also after the heat pipe processing, that is, after the completion of the plate type heat pipe. The high flatness of the contact surface with the heat-generating component to be cooled is easily realized. Therefore, it is understood that the plate-type heat pipe of the present invention can be easily connected to a heat-generating component with low thermal resistance, and excellent cooling performance can be practically realized by using this. Although not described in detail, the thermal performance of the plate-type heat pipe 4 of the example of the present invention and the plate-type heat pipe 45 of the comparative example were the same except for the thermal resistance with the heat-generating component.

[0030]

As described in detail above, the plate-type heat pipe of the present invention can be easily connected to a heat-generating component with a low thermal resistance, and if it is used, excellent cooling performance can be realized practically. It is.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a plate-type heat pipe according to the present invention.

FIG. 2 is a sectional view showing another example of the plate-type heat pipe according to the present invention.

FIG. 3 is a sectional view showing another example of the plate-type heat pipe according to the present invention.

FIG. 4 is an explanatory diagram showing an assembling state of the plate-type heat pipe according to the example of the present invention.

FIG. 5 is an explanatory diagram showing an assembling state of the plate-type heat pipe according to the example of the present invention.

FIG. 6 is an explanatory diagram showing an assembling state of a plate-type heat pipe according to a comparative example.

FIG. 7 is a cross-sectional view showing a conventional plate-type heat pipe and an application example thereof.

FIG. 8 is a sectional view showing a conventional plate-type heat pipe and an application example thereof.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 plate heat pipe 10 upper plate 11 lower plate 120 solid portion 121 solid portion 122 solid portion 13 hollow portion 2 plate type heat pipe 21 lower plate 22 upper plate 220 solid portion 221 solid portion 222 solid portion 23 Cavity part 3 Plate type heat pipe 30 Upper plate 31 Lower plate 320 Solid part 321 Solid part 322 Solid part 33 Cavity part 40 Upper plate 41 Lower plate 420 Solid part 421 Solid part 43 Upper plate 440 Solid part 441 Solid portion 44 Lower plate 45 Plate heat pipe 5 Plate heat pipe 50 Container 501 Hollow portion 51 Heat radiating fin 52 Heat generating component 53 Lead 54 Printed circuit board 6 Plate heat pipe 60 Container 601 Hollow portion 61 Heat radiating fin 62 Heat generating component 620 Heat generation Components 63 Lead 64 Printed circuit board

Claims (6)

[Claims] 1. A plate heat pipe provided to face a substrate on which a component to be cooled is mounted, wherein a portion corresponding to the component to be cooled penetrates to both main surfaces of the plate heat pipe. A plate-type heat pipe provided with a real part. 2. The plate-type heat pipe according to claim 1, wherein the solid portion protrudes toward a surface facing the component to be cooled. 3. The plate heat pipe according to claim 1, wherein the solid portion is formed of the same member as one main surface of the plate heat pipe. 4. The plate-type heat pipe according to claim 1, wherein the solid portion does not form a part of an inner wall of the cavity in which the working fluid is stored. 5. The plate-shaped heat pipe is disposed opposite to a printed circuit board on which a semiconductor component is mounted as a component to be cooled, and the semiconductor component is connected to the plate-shaped heat pipe. A cooling structure using a plate-type heat pipe to which a heat sink is joined. 6. The cooling structure according to claim 5, further comprising a fan for sending air to the heat sink.