JP3106429B2 - Plate type heat pipe and cooling structure using it - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plate-type heat pipe and a cooling structure for a cooled element such as a semiconductor element 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 and electronic devices such as power equipment are inevitable to generate a certain amount of heat by use thereof. It is becoming a technical issue. As a method of cooling an electric / electronic element requiring cooling (hereinafter referred to as a cooled element), for example, a fan is attached to a device,
Representatively known are a method of lowering the temperature of the air in the equipment housing, a method of particularly cooling the element to be cooled by attaching a cooling body to the element to be cooled, and the like.

As a cooling body attached to the element to be cooled, a plate made of a material having excellent heat conductivity such as a copper material or an aluminum material is used. It is more effective to attach a heat dissipating fin to such a plate or to use a plate and a fin integrally formed (by casting or forging). This type of cooling body is sometimes called a heat sink or the like.

In recent years, as a cooling body to be attached to an element to be cooled, a heat pipe is attached to a cooling body having a heat pipe structure or a plate having excellent heat conductivity, such as a copper material or an aluminum material, instead of a mere heat conductive metal material. Is proposed and put to practical use.

The heat pipe has a sealed cavity, and heat is transferred by phase transformation and movement of the working fluid contained in the cavity. Of course, some heat is transferred by conducting heat through a container (container) constituting the heat pipe. However, the heat pipe is a heat transfer device mainly intended to perform a heat transfer operation by a working fluid.

[0006] The operation of the heat pipe is briefly described as follows. That is, on the heat absorbing side of the heat pipe, the working fluid evaporates due to heat transmitted through the material of the container (container) constituting the heat pipe, and the vapor moves to the heat radiation side of the heat pipe. On the heat radiation side, the vapor of the working fluid is cooled and returns to the 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.

In the case of a gravity type heat pipe, the working fluid which has been brought into a liquid phase state by phase transformation moves (refluxes) to the heat absorbing side by gravity or capillary action. In this case, the heat absorption side may be disposed below the heat radiation side.

[0008] The working fluid in the heat pipe is usually
Water, an aqueous solution, alcohol, and other organic solvents are used. As a special application, mercury may be used as a working fluid. As described above, since the heat pipe utilizes the action such as phase transformation of the working fluid inside, the heat pipe is manufactured so as to minimize mixing of gases and the like other than the working fluid into the sealed interior. . Such contaminants are usually air (air) mixed during the production or carbon dioxide dissolved in the working fluid.

In addition to a typical round pipe shape, a heat pipe shape of a flat type has recently attracted attention. The flat type heat pipe has advantages such as easy contact with a cooled element such as a semiconductor element over a large area due to its shape.

As such a flat heat pipe, 2
There have been proposed ones in which two flat plates are joined by welding or the like so that a cavity is formed between them, or one in which two flat plates partially coated with a release agent are joined and then expanded to form a cavity. ing.

[0011]

As a method of cooling a semiconductor element or the like (cooled element) mounted on a printed circuit board by using a heat pipe, for example, a heat pipe is arranged above the mounting surface side of the printed circuit board. Then, there is a method of contacting with a semiconductor element to be cooled. In this case, the heat pipe and the semiconductor element may be brought into contact with each other via heat transfer grease or the like.

However, the number of semiconductor elements mounted on a printed circuit board is not limited to one. There may be a plurality of elements that require cooling, but these semiconductor elements are not necessarily all of the same shape, and the amount of heat generated is usually not constant. Therefore, in the case of a mere flat plate heat pipe, it is necessary to cool them, and it is difficult to bring all of the semiconductor elements into contact with one flat plate heat pipe.

Therefore, a method of preparing a plurality of heat pipes and bringing the heat pipes into contact with each element can be considered. However, in such a method (form), there is a problem in space around the printed circuit board, There are many problems in terms of cost using a heat pipe.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances. The plate-type heat pipe of the present invention is a plate-type heat pipe provided to face a substrate on which a plurality of elements to be cooled are mounted, and a container wall of the plate-type heat pipe on a side facing the element to be cooled. Are formed in a convex shape according to the distance from the element to be cooled, and corrugated fins are provided inside the convex portion. Further, a plate-type heat pipe provided to face a substrate on which a plurality of elements to be cooled are mounted,
The container wall of the plate-type heat pipe on the side opposite to the element to be cooled is formed into a convex shape in accordance with the distance to the element to be cooled, and a block is provided inside the convex portion, and the block is provided. Provided is a plate-type heat pipe in which a clearance that exhibits a capillary effect is formed by the inner wall of the projection on the cooling element side and the block.

The plate type heat pipe of the present invention may be provided with a wick therein. When a block is provided inside the projection, the inner wall of the projection on the element to be cooled side and the block may be joined at the clearance.

It is preferable that an embossed portion is provided on the container wall facing the element to be cooled or on the side facing the element to be cooled, and the embossed portion is joined to the facing container wall.

According to the present invention, there is provided a cooling structure using a plate-type heat pipe in which any one of the above-described plate-type heat pipes is used, and the convex portion and the element to be cooled are thermally connected.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a view for explaining a plate type heat pipe of the present invention and a cooling structure using the same.
FIG. 1A is a partial sectional view thereof. On the lower side of the plate-shaped heat pipe 10 in the drawing, elements 20, 21, and 22 to be cooled, such as semiconductor elements, are mounted on a printed circuit board 30 (FIG. 1A). In this example, the number of elements to be cooled is three, but this number is arbitrary.
Reference numeral 23 in the drawing denotes a lead of the element to be cooled 20, 21, 22.

The heights of the cooled elements 20, 21, and 22 from the printed circuit board 30 are different from each other. The plate-type heat pipe 10 is provided to face the substrate 30 on which the elements to be cooled 20, 21, and 22 are mounted. The plate-shaped heat pipe 10 has opposed elements 20 and 21 to be cooled.
A predetermined convex portion 13 is provided in accordance with the distance to 22 (only one of three convex portions is denoted by reference numeral 13 for simplicity). Therefore, the cooled elements 20, 2
Even when the heights of the elements 1 and 22 are different from each other, the elements to be cooled 20, 21 and 22 can be brought into thermal contact with one plate-type heat pipe 10.

The elements 20, 21, and 22 to be cooled and the plate-type heat pipe 10 may be in direct contact with each other.
The contact may be made by interposing a heat transfer sheet or heat transfer grease. Alternatively, they may be joined by solder or the like. The heat transmitted from the elements to be cooled 20, 21, 22 to the plate-type heat pipe 10 is generally radiated through the fins 31. In FIG. 1, heat transfer sheets, heat transfer grease, and the like existing between the cooled elements 20, 21, and 22 and the plate-type heat pipe 10 are not shown.

Cavity 1 Constituting Plate Heat Pipe 10
2 is formed by joining the upper plate 110 and the lower plate 111. The material of the upper plate 110 and the lower plate 111 constituting the container 11 is not particularly limited, but it is desirable to use a copper material or an aluminum material having excellent heat conductivity. Fig. 1 (A)
Although not shown, a working fluid is appropriately accommodated in the hollow portion 12. The working fluid may be selected in consideration of compatibility with the material of the content 11 and the like. For example, water,
Alternative Freon, Fluorinert, etc. can be applied. Further, the inside of the cavity 12 is cleaned, vacuum degassed, and the like so that the phase change of evaporation and condensation of the working fluid is easily performed.

In this example, the plate type heat pipe 10 includes:
A mesh 112 is provided in the cavity 12 as a wick. The mesh usually refers to a mesh sheet. By providing the mesh 112, the effect of recirculating the working fluid by the capillary action can be expected, and the heat transfer performance is further improved. Here, the mesh 112 is provided along the lower plate 111. However, it is preferable that the mesh sheet constituting the mesh 112 is appropriately subjected to drawing or cutting in accordance with the form of the projections 13.

The container 11 constituting the plate-type heat pipe 10 in this embodiment is composed of an upper plate 110 and a lower plate 11 provided with convex portions 13 (three convex portions are present in the example of this figure).
1 and joined together. The plate type heat pipe 10 in this example has at least one convex portion with a corrugated fin 40.
Has been arranged. FIG. 1A is an explanatory view showing the assembly of the plate-type heat pipe 10, and FIG. 1C is a perspective view for explaining the schematic shape of the corrugated fin 40.

When the working fluid (not shown) evaporates due to the heat of the component 21 to be cooled, the corrugated fin 40 has an effect of increasing the area of the evaporating portion. That is, the area of the evaporator for transmitting the heat of the cooled component 21 to the working fluid increases. In the present invention, since the shape of the corrugated fin 40 is corrugated, the contact area with the working fluid increases, and a large increase in the area of the evaporator can be expected. The material of the corrugated fin 40 is not particularly limited, but it is desirable to use a copper or aluminum material having excellent thermal conductivity so that more heat of the component to be cooled 21 is transmitted. The shape of the corrugated fin 40 is not particularly limited, but it is practical if a fin obtained by corrugating a metal sheet (sometimes called a corrugated fin) is applied.

The corrugated fins 40 are desirably joined to the container 11. In particular, the upper plate 110 and the lower plate 111
(The bottom of the inner surface of the convex portion) contributes to the improvement of the pressure resistance of the plate-type heat pipe 10. The lower plate 11
If you join with excellent thermal connectivity such as brazing with 1,
Desirably, the heat of the component to be cooled 21 is easily conducted by the corrugated fins 40. Such corrugated fins 40 may be provided on all of the projections 13 corresponding to the elements to be cooled 20, 21, and 22.
It is particularly desirable to provide the element having the largest heat flow rate among the elements 1 and 22 (in this example, the element to be cooled 21 is the element having the largest heat flow rate). This is because the provision of the corrugated fins 40 substantially increases the surface area of the evaporator for evaporating the working fluid by the heat of the element to be cooled 21.

FIG. 2 is an explanatory view showing another example of the plate-type heat pipe of the present invention. In this example, the plate type heat pipe 1
00, a mesh 103 is provided in a cavity 104, and a lower plate 1 constituting a container 101 in addition to the corrugated fins 102.
An embossed portion 70 is formed by embossing a part of the portion 011. In this example, the mesh 103 is provided along the upper plate 1010.

Usually, as shown in FIGS. 1 and 2,
During operation, the plate-shaped heat pipe tends to swell in the thickness direction of the plate due to an increase in internal pressure due to evaporation of the internal working fluid. Therefore, as shown in the example shown in FIG. 2, in order to suppress the swelling deformation of the plate-type heat pipe 100 due to an increase in internal pressure, an embossed portion is provided on the lower plate 1011 and / or the upper plate 1010, or both, by embossing. It is good to work as a support. In this example, the embossed portion 70 and the embossed portion 71 are provided on the lower plate 1011, and the embossed portion 70 is joined to the upper plate 1010 to have a function as a support. The embossed portion 71 is slightly lower in height than the embossed portion 70, and the mesh 103 is formed on the upper plate 1011.
At the same time, the function to make it adhere to is also functioning.

FIG. 3A is an explanatory view showing another example of the plate-type heat pipe of the present invention. In this example, a mesh 54 is provided in the hollow portion 52 of the plate-type heat pipe 50,
A block 53 is provided in one of the convex portions 55 (one of the convex portions is denoted by reference numeral 55 for simplicity in the drawing). The mesh 54 is arranged so as to cover the inner periphery of the cavity 52. The block 53 may be joined to the mesh 54 or the inner wall of the container 51.

FIG. 3A is a diagram for explaining a fixed state of the block 53. In this example, the upper surface side of the block 53 is joined to the upper plate 510 by brazing with a part of the mesh 54 interposed therebetween. Reference numeral 530 in the drawing indicates a brazing portion.
The lower surface of the block 53 is not joined to the inner wall of the lower plate 511, and a slight clearance is formed between them. This makes it easier for the working fluid to collect at the clearance between the lower surface of the block 53 and the inner wall of the lower plate 511 due to the capillary action, so that the heat from the element to be cooled 21 is more efficiently radiated.

FIG. 4 is an explanatory diagram showing another form of the block. The block 531 is provided with a slight protrusion on the lower surface side, and the protrusion is joined to the inner wall of the lower plate 513. The upper surface of the block 531 has an upper plate 512 sandwiching a part of the mesh 54 in the same manner as in the case shown in FIG.
Has been brazed to. Reference numerals 532 and 541 in the drawing indicate brazing portions.

Also in this example, as in the example shown in FIG. 3A, the clearance between the lower surface of the block 531 and the inner wall of the lower plate 513 exerts a capillary action, thereby exhibiting the effect of drawing in the working fluid. ing. In addition, since the block 531 is joined to both the upper plate 512 and the lower plate 513, the block 531 also exhibits the function of the above-described support.

Returning to FIG. In this example, block 5
3 is provided in the portion of one convex portion 55, but such a block includes all the convex portions 55 (three convex portions 5 in this figure).
5). FIG. 5 shows the case where blocks 630, 631, and 632 are provided on all three convex portions.
The number of blocks provided among the plurality of convex portions is arbitrary.

It is desirable to use a block provided with projections and depressions on the surface as the block provided on the projection from the viewpoint of increasing the surface area and reducing the weight. FIGS. 6A and 6B show examples of blocks having irregularities formed on the surface. In this drawing, a block whose entire shape is substantially H-shaped by forming irregularities is illustrated. Incidentally, reference numerals 74 and 7 in FIG.
Reference numeral 5 denotes a convex portion to be provided for each of the blocks 70 and 71.

The plate-type heat pipe of the present invention described above facilitates thermal connection with a plurality of elements to be cooled, each of which has a different mounting height, and realizes an effective cooling structure with space efficiency and the like. is there. The corrugated fins allow for more efficient cooling of the element to be cooled. Further, by providing a block on the convex portion provided on the plate-shaped heat pipe and forming a clearance having a capillary effect by the block, it is possible to cool the element to be cooled more efficiently. These blocks and corrugated fins can also function as pillars for improving the pressure resistance of the plate-type heat pipe.

[0035]

As described above, the plate-type heat pipe of the present invention is suitable for cooling a plurality of elements to be cooled, and when the height of the plurality of elements to be cooled is different from each other. Even when the heat velocities of the respective cooled elements are different, these efficient cooling structures can be realized.

[Brief description of the drawings]

FIG. 1A is an explanatory view showing an example of a plate-type heat pipe according to the present invention and an example of a cooling structure using the same.
(A) is an explanatory view showing the situation during the assembly, (c)
FIG. 4 is a perspective view illustrating a corrugated fin.

FIG. 2 is an explanatory view showing another example of the plate-type heat pipe according to the present invention and another cooling structure using the same.

FIG. 3A is an explanatory view showing another example of the plate-type heat pipe according to the present invention and another cooling structure using the same. (A) is an explanatory view showing a joining state of blocks.

FIG. 4 is an explanatory diagram showing a joining state of blocks.

FIG. 5 is an explanatory view showing another example of the plate-type heat pipe according to the present invention and another cooling structure using the same.

FIGS. 6A and 6B are explanatory diagrams showing examples of block shapes according to the present invention. FIGS.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Plate-type heat pipe 11 Container 110 Upper plate 111 Lower plate 112 Mesh 12 Cavity part 13 Convex part 20, 21, 22 Element to be cooled 23 Lead 30 Printed circuit board 31 Fin 40 Corrugated fin 100 Plate-type heat pipe 101 Container 1010 Upper plate 1011 Lower plate 102 Corrugated fin 103 Mesh 104 Hollow portion 70 Emboss portion 71 Emboss portion 50 Plate heat pipe 51 Container 510 Upper plate 511 Lower plate 52 Hollow portion 53 Block 54 Mesh 55 Convex portion 530 Brazing portion 540 Brazing portion 512 Upper plate 513 Lower plate 532 Brazing portion 541 Brazing portion 60 Plate heat pipe 61 Container 62 Hollow portion 630 block 631 block 632 block 64 Mesh 70 block 71 block 72 Lower plate 73 Lower plate 4 convex portion 75 projecting portion

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-8-86578 (JP, A) JP-A-52-90852 (JP, A) JP-A 5-79259 (JP, U) JP-A 61-86259 161565 (JP, U) Japanese Utility Model Showa 61-161560 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F28D 15/02 H01L 23/427

Claims (7)

(57) [Claims] 1. A plate-type heat pipe provided to face a substrate on which a plurality of elements to be cooled are mounted, wherein a container wall of the plate-type heat pipe on a side facing the element to be cooled faces. A plate-shaped heat pipe formed into a convex shape according to a distance from an element to be cooled, and having a corrugated fin inside the convex portion. 2. A plate-type heat pipe provided to face a substrate on which a plurality of elements to be cooled are mounted, wherein a container wall of the plate-type heat pipe on a side facing the element to be cooled faces. It is formed into a convex shape in accordance with the distance to the element to be cooled, and a block is provided inside the convex, and a clearance that produces a capillary effect is formed by the block and the inner wall of the convex portion on the element to be cooled. A plate-type heat pipe. 3. The plate-type heat pipe according to claim 2, wherein the block has a surface having irregularities. 4. The plate heat pipe according to claim 1, wherein a wick is provided inside the plate heat pipe. 5. The plate heat pipe according to claim 3, wherein a wick is provided inside the plate heat pipe, and the block and the wick are joined at the clearance portion. 6. An embossed portion is provided on a container wall of the plate-type heat pipe on a side facing the element to be cooled or on a side facing the element, and the embossed portion is joined to the facing container wall. Item 6. A plate-type heat pipe according to any one of Items 1 to 5. 7. The plate-shaped heat pipe according to claim 1, wherein the projection and the element to be cooled are thermally connected.
Cooling structure using plate heat pipe.