JP3438944B2 - Heat pipe type heat radiating unit and manufacturing method thereof - Google Patents

Abstract

PURPOSE:To reduce the thickness of a heat transferring plate so as to reduce the weight and thickness of a heat pipe type heat radiating unit as a whole by press-fixing both surfaces along the longitudinal axes of some or all heat pipes inserted into pipe inserting holes of the heat transferring plate to internal surfaces of the holes along the longitudinal axes of the holes. CONSTITUTION:In a heat transferring plate 2, pipe inserting holes 20 having flat (or elliptic) cross sections are formed at nearly equal intervals. The evaporating sections 10 of heat pipes 1 inserted into and fixed to the holes 20 have flat (or elliptic) cross sections and their both surfaces along their longitudinal axes r1 are press-fixed to the upper and lower internal surfaces of the holes 20 along the longitudinal axes R1 of the holes 20. The condensing sections 11 of the pipes 1 are fitted with heat radiating plates 3. The heat generated by heat generating parts is transferred to the evaporating sections 10 of the pipes 1 through the plate 2, evaporates a working fluid in the sections 10, is carried to the low-temperature and low-pressure condensing sections 11 by the vapor of the working fluid, and is discharged to the outside air through heat radiating fins 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat pipe type heat radiating unit for cooling a heat generating component such as an LSI mounted in an electronic device, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, in many cases, a forced air cooling system using an air cooling fan has been adopted as a means for preventing overheating in electronic equipment. However, in recent electronic devices,
Since heat-generating components such as LSIs (Large Scale Integrated Circuits) are mounted at high density and the amount of heat generated in the device tends to increase significantly, the cooling capacity of the air-cooled fan method is limited. Moreover, since the mounting space of the heat dissipation unit in the device is becoming narrower with the downsizing of the electronic device, it is becoming extremely difficult to dissipate the heat in the electronic device.

In view of the above situation, the inventors have already proposed a small heat dissipation unit using a small-diameter heat pipe and having a high cooling capacity (Japanese Patent Application No. 4-105382).
issue). 10 and 11 are a perspective view and a side view of the heat pipe type heat dissipation unit proposed by the inventors.

This heat dissipating unit includes two heat pipes 1 each having a flat cross section with an outer diameter of about 1.5 mm in the minor axis direction.
The heat pipes 8 and 9 are attached to the evaporating portion 10 and the condensing portion 11 of each heat pipe 1, and the radiation fins 30 are attached to both surfaces of the heat transmitting plate 9. The heat transfer plate 8 on the evaporator side is composed of a flat plate-shaped main body 80 and a lid 81,
As shown in FIG. 12, the evaporation portion 10 of the heat pipe 1 is inserted into the groove 82 formed on the surface of the main body 80, and the solder 83 is inserted into the gap between the inner wall of the groove 82 and the evaporation portion 10 of the heat pipe 1.
Is melted, a lid 81 is covered on it, and it is fixed with solder 83.

The heat transfer plate 9 on the side of the condenser is a flat plate having a thickness of about 3.5 mm obtained by bonding two aluminum plates together by soldering, and heat is placed in the groove formed in one or both of the plates. The condenser portion 11 of the pipe 1 is inserted and fixed by soldering. The radiating fins 30 and 30 fixed to both surfaces of the heat transfer plate 9 by soldering are formed by alternately laminating a plate-shaped fin member and two fin members of the same shape pressed into a rectangular wave shape and brazing. It is fixed in.

As shown in FIG. 11, the heat pipe type heat radiating unit configured as described above has a heat generating component such as an LSI on a printed circuit board 7 via a high heat conductive rubber 6 having good heat conductivity to the back surface of the main body 80. 5 and the heat transfer plate 8 in this state
Is attached to the printed circuit board 7 for use. In the mounted state as shown in FIGS. 10 and 11, the main body 80 of the heat transfer plate 8 and the high thermal conductive rubber 6 form a heat absorbing part, and the heat transfer plate 9 and the heat radiating fins 30 form a heat radiating part.

In the mounted state of FIGS. 10 and 11, the heat generated in the heat-generating component 5 such as an LSI is transferred to the heat transfer plate 8 via the high heat conductive rubber 6, and the evaporation section 1 of the heat pipe 1 is transferred.
0 is heated to evaporate the working fluid sealed inside. Due to the evaporation of the working liquid, the vapor pressure in the vaporization section 10 of the heat pipe 1 increases, and a vapor flow is generated in the condensation section 11 having a low pressure. The heat of the vapor that has moved to the condensing unit 11 is transmitted to the radiating fins 30 via the heat transfer plate 9, and is dissipated into the atmosphere from the entire surface of the radiating fins 30 in contact with air.

The heat transfer plate 9 is a condenser portion 11 of the heat pipe 1.
Since the heat from the heat pipe 1 can be diffused and transmitted to the part far from the heat pipe 1, the temperature of the whole becomes almost uniform. Radiating fins 30 attached to the heat transfer plate 9
, The surface area per unit volume is very large and Den
From the surface of the heat plate 9 to the upper radiation fin 3 in FIG.
The distances to the upper surface of 0 and the lower surface of the lower radiation fin 30 are small. Therefore, the radiation fin 30
A large temperature drop does not occur even in the part farthest from the heat transfer plate 9 and the entire heat dissipation fin 30 has a substantially uniform temperature, so that the heat dissipation effect is improved by the increase in the surface area. For these reasons, the heat pipe type heat radiating unit of FIGS. 10 and 11 proposed by the inventors has an effect that the heat radiating performance can be remarkably improved even if it is relatively small.

[0009]

By the way, the main body 80 of the heat transfer plate 8, the lid 81 and the evaporation portion of the heat pipe 1 in the heat pipe type heat dissipation unit are fixed by the solder 83 as described above. . However, in the method of fixing the heat transfer plate to the heat pipe by soldering, since the solder is heavy, if the solder layer is thick, the weight of the heat dissipating unit may increase, or the space between the main body 80 and the lid 81 may be increased. There is a problem that the appearance of the solder 83 is impaired by the protrusion of the solder 83. On the other hand, if the solder layer is thinned in order to reduce the weight of the heat dissipation unit, voids 84 are likely to occur in each part of the layer of the solder 83 when manufacturing the heat dissipation unit. These void 8
4, the thermal resistance of the contact portion between the heat transfer plate and the heat pipe 1 is increased, and the thermal resistance varies, so that the heat radiation performance is deteriorated.

Further, as described above, as the weight and size of electronic equipment have been reduced, it has been required to reduce the weight and size of this type of heat dissipation unit. However, in order to reduce the weight and size of the heat dissipation unit, as shown in FIG. 12, a flat plate-shaped main body 80 and a lid 81 are made of, for example, aluminum or an aluminum alloy, and the main body 80 and the lid 81 form a heat pipe. In the case of fixing with sandwiching 1, the heat transfer plate 8 could not be made smaller (thinner) to a certain extent or less for the following reason.

The first reason is that if the main body 80 and the lid 81 are too thin, the heat transfer plate 8 is deformed with time, or the joint between the heat pipe 1 and the heat transfer plate 8 is separated with time. It is easy to do. The second reason is that the main body 80, the lid 81, and the heat pipe 1 are connected to each other in order to improve the adhesion between the heat transfer plate 8 and the heat-generating component 5 and prevent the heat transfer between them from decreasing. After soldering, it is necessary to machine the surface of the main body 80 in contact with the heat-generating component 8 by cutting, but if the main body 80 and the lid 81 are too thin, the above-mentioned cutting process becomes impossible or difficult. Is. That is, when the heat transfer plate 8 is fixed with a cutting tool (not shown) and is cut as described above, the lid 81 is deformed or the main body 80 is
The lid 81 may peel off.

On the other hand, if the heat transfer plate is not formed by the laminated structure as shown in FIGS. 10 to 12 and is integrally formed of aluminum or aluminum alloy, or if it is integrated in advance before being attached to the heat pipe 1, the heat transfer is performed. Since the strength of the plate is improved, it can be made thinner, but in this case, another problem occurs. That is, in order to fix the heat pipe to the integrated heat transfer plate, in the conventional technique, a pipe insertion hole is formed in the thickness portion of the heat transfer plate, and the heat pipe is inserted into this pipe insertion hole to heat the heat transfer plate. Depending on the method of pouring the solder into the gap between the pipe surface and the inner wall of the pipe insertion hole, when the material is aluminum, for example, the oxide layer formed on the surface hinders the adhesion of the solder, so the heat pipe surface Many voids are generated between the inner wall of the pipe and the inner wall of the pipe insertion hole. The voids increase the thermal resistance as described above and reduce the heat dissipation performance of the unit. Also,
In order to fix the heat pipe in the pipe insertion hole so that voids do not occur, it is necessary to enlarge the pipe insertion hole to increase the amount of solder to be poured, but the increased amount of solder increases the weight of the heat dissipation unit. In addition, since it is necessary to increase the thickness of the heat transfer plate due to the necessity of enlarging the pipe insertion hole, it is impossible to reduce the thickness of the heat transfer plate.

For example, in a heat dissipation unit for cooling an LSI mounted in a notebook personal computer, a heat transfer plate needs to be thin (for example, 3 mm or less) for downsizing. Insert a small-diameter heat pipe into the pipe insertion hole formed in the thickness part of the heat transfer plate, and solder the heat pipe to fix it so that the above-mentioned voids are few and the heat resistance does not become high. For example, it is necessary to process the heat pipe into a flat shape so that its short axis becomes smaller. However, if a small-diameter heat pipe is flattened so that its short axis becomes too small, there arises a problem that the heat transport amount in the flattened portion is significantly reduced. Various problems relating to the fixing of the heat transfer plate 8 and the heat pipe 1 as described above are caused by other heat transfer plates 9
The same applies to the fixing of the heat pipe 1 with the heat pipe 1.

An object of the present invention is to provide a heat pipe type heat dissipation unit in which the thickness of the heat transfer plate can be made thinner to reduce the overall weight and thickness. Another object of the present invention is to provide a heat pipe type heat dissipation unit having a small thermal resistance between a heat transfer plate having a small thickness and a heat pipe. Still another object of the present invention is to fix a heat transfer plate and a heat pipe so that thermal resistance does not become large when using a thinner heat transfer plate that is integrally molded or previously integrated, Moreover, it is to provide a manufacturing method of a heat pipe type heat dissipation unit suitable for mass production.

[0015]

In order to achieve the above-mentioned object, a heat pipe type heat dissipation unit according to the present invention has one or several heat pipes attached to a heat transfer plate, and an electronic device via the heat transfer plate. In a heat pipe type heat dissipation unit for exchanging heat with heat generating parts of the equipment and the heat pipe,
A pipe insertion hole having a substantially flat or oval cross section is formed in a thickness portion of the heat transfer plate so that a long axis extends along one surface of the heat transfer plate, and at least a part of the heat pipe is formed in the pipe insertion hole. Is inserted, and the inserted portion of the heat pipe inserted into the pipe insertion hole is formed such that its cross section has a substantially flat or oval shape, and both surfaces along the long axis thereof have a long length of the pipe insertion hole. Almost uniform on the inner wall surface along the axis
It is characterized in that it is crimped in a close contact state .

The inserted portion of the heat pipe inserted into the pipe insertion hole has a minor axis / long axis = 0.6 or less,
Moreover, it is desirable that the minor axis is 1.5 mm or more. The heat transfer plate can be manufactured by extrusion molding or other plastic working, casting, machining, or the like, but is preferably made of an extruded shape and has a thickness of 2.5 mm.
The above is desirable. The inserted portion of the heat pipe inserted into the pipe insertion hole has one surface or both surfaces along the long axis of the heat pipe to the inner wall surface of the pipe insertion hole via a thin solder (for example, Sn-Zn system) layer. It does not matter if they are closely attached. In the heat dissipation unit, when a part of the heat pipe is inserted into the pipe insertion hole of the heat transfer plate, the heat dissipation fin is attached to all or a part of the other part of the heat pipe in a used state. In the heat dissipation unit, when all of the heat pipes are inserted into the pipe insertion holes of the heat transfer plate, it is preferable to attach a heat dissipation fin to a part of the heat transfer plate.

In order to achieve the above-mentioned object, the method of manufacturing a heat pipe type heat dissipation unit according to the present invention has one or a plurality of heat pipes attached to a heat transfer plate, and heat generated from an electronic device through the heat transfer plate. In a method of manufacturing a heat pipe type heat dissipation unit for exchanging heat between a component and the heat pipe, a flat or long member having a major axis formed in a thickness portion of the heat transfer plate substantially parallel to one surface of the heat transfer plate. In the pipe insertion hole having a circular cross section, the inserted portion having a flat or oval cross section including a part or all of the heat pipe, and the long axis of the insertion portion being substantially along the long axis of the pipe insertion hole. And a step of inserting the inserted portion into the short axis direction by heating the heat pipe, thereby forming both surfaces along the long axis of the inserted portion on the inner wall surface along the long axis of the pipe insertion hole. Work to crimp to It is characterized in that it comprises and.

In the above-mentioned manufacturing method, the inserted portion including a part or the whole of the heat pipe has a cross section of a pipe having a heat transfer plate after the working fluid is sealed therein or before the working fluid is sealed therein. The flattened or oval shape is processed in advance so that the size is slightly smaller than the hole.

As the heat transfer plate, one integrally molded or previously integrally processed is used. Although the pipe insertion hole may be formed in this heat transfer plate by mechanical means,
It is preferable to extrude a long plate in a state where the pipe insertion hole is formed in the length direction and cut the long plate to an appropriate size to use as a heat transfer plate. When the heat transfer plate and heat pipe are small in size, insert the heat pipe into the pipe insertion hole of the heat transfer plate when heating the heat pipe, and restrain the heat transfer plate with an appropriate holder in this state. It is preferable to heat in this state. For heating the heat pipe, only the heat pipe may be heated, or the heat pipe may be heated together with the heat transfer plate.

When the heat radiation fins are attached to the condensing portion of the heat pipe, the heat radiation fins may be directly attached to the heat pipe, or the condensing portion of the heat pipe is processed in advance so as to have a flat or oval cross section. A heat transfer plate may be fixed to the condensing portion by a method similar to the method of the present invention described above, and a radiation fin may be attached to the heat transfer plate.

[0021]

According to the heat pipe type heat dissipation unit of the present invention, as described above, a part or all of the heat pipe inserted into the pipe insertion hole of the heat transfer plate has both surfaces along the major axis thereof. It is crimped to the inner wall surface along the long axis of the pipe insertion hole of the heat transfer plate. Therefore, the heat transferred from the heat generating component to the heat transfer plate is transferred to the heat pipe mainly through the close contact surface between the inner wall surface of the heat transfer plate along the long axis of the pipe insertion hole and the heat pipe. .

Since a part or all of the heat pipe has its both surfaces along the major axis thereof crimped to the inner wall surface along the major axis of the pipe insertion hole of the heat transfer plate in a substantially intimate contact state, the thermal resistance is small and good. The heat transfer is done to. Since the heat transfer plate is integrally molded or integrally processed in advance, sufficient strength can be maintained even if it is made thinner. Therefore, the entire heat dissipation unit can be made thinner and lighter.

Since the method for manufacturing the heat pipe type heat dissipation unit according to the present invention includes the steps as described above, both surfaces of the heat pipe along the major axis of the inserted portion are arranged from the inside in the minor axis direction of the heat pipe. The force acting along the inner surface of the heat transfer plate is pressed against the inner wall surface of the pipe insertion hole along the long axis in a substantially uniform contact state. Therefore, the thermal resistance of the crimping portion between the both surfaces of the heat pipe along the major axis of the inserted portion and the inner wall surface of the heat transfer plate along the major axis of the pipe insertion hole is small and substantially uniform so that there is no variation. As a result, the heat transfer performance is improved even if the contact area between the heat pipe and the heat transfer plate is small. Therefore, again, by using a thinner heat transfer plate with integral molding,
It is possible to manufacture a small and lightweight heat pipe type heat dissipation unit having higher heat transfer performance. Furthermore, since the cross-sectional area of the inserted portion of the heat pipe expands due to expansion and tube expansion, the heat transport amount increases as compared with that before tube expansion.

A large amount of the above-mentioned heat transfer plate is manufactured in advance,
Insert the flat or oval cross-section inserted part of the heat pipe into the pipe insertion hole of each heat transfer plate as described above,
By holding these for a predetermined time in a heating furnace that is controlled to a temperature sufficient for the heat pipe said inserted portion to expand, for example, a heat pipe type heat dissipation unit having high performance and substantially uniform heat dissipation performance is obtained. It is cheaper and can be manufactured in large quantities.

In order to bring both the flat and oval portions of the heat pipe into close contact with the inner wall of the pipe insertion hole of the heat transfer plate, after inserting the heat pipe into the pipe insertion hole of the heat transfer plate, the heat transfer plate is attached. A means for pressing in the crimping direction can be considered. However, according to such a means, the insertion portion of the heat pipe into the pipe insertion hole is plastically deformed by pressing, and is pressed against the inner wall of the pipe insertion hole by the resistance against this plastic deformation, so that the heat pipe surface The pressure-bonded portion with the inner wall of the pipe insertion hole tends to be insufficient in strength, and it is difficult to make the contact state uniform in each portion. On the other hand, according to the method of the present invention, both sides of the flat portion or the oval portion of the heat pipe are pressed against the inner wall of the pipe insertion hole of the heat transfer plate by the expansion force from the inside of the heat pipe as described above. Therefore, even if the heat pipe has a small diameter and the heat transfer plate is thin, the pressure-bonding portion has a sufficient strength and a substantially uniform contact state. Therefore, when manufacturing the heat dissipation unit according to the present invention,
It is preferably produced by the method of the present invention rather than by means of pressing as described above.

According to the heat pipe type radiator manufacturing method of the present invention, the heat pipe is heated and both surfaces along the major axis thereof are crimped to the inner wall surface along the major axis of the pipe insertion hole of the heat transfer plate. Only by itself, a gap is formed between the surface of the inserted portion of the heat pipe and both ends or one end of the pipe insertion hole in the long axis direction. The gap may be filled by pouring molten solder in a later step, but it can be implemented without degrading the heat radiation performance of the heat radiation unit without filling the solder. However, when the heat pipe has a small diameter (for example, the short diameter of the heat pipe evaporation portion after manufacturing the heat dissipation unit is 1.5 mm to 3 mm) and the gap is not filled with solder, the evaporation portion of the evaporation portion is not filled. It is desirable to manufacture such that the ratio of minor axis / major axis is 0.6 or more.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a heat pipe type heat dissipation unit and a manufacturing method thereof according to the present invention will be described with reference to FIGS. 1 is a partially omitted plan view showing an embodiment of a heat pipe type heat dissipation unit manufactured by the manufacturing method of the present invention, FIG. 2 is a partially enlarged sectional view taken along the arrow AA of FIG. 1, and FIG. 1 is a partially enlarged cross-sectional view showing a state before the evaporation portion of the heat pipe is heated and expanded in the heat radiation unit 1, FIG. 4 is a partially enlarged cross-sectional view showing another embodiment of the heat pipe type heat radiation unit according to the present invention, and FIG. Figure 1
7 is a front view of the heat pipe type heat radiating unit of the embodiment in a tilted state, FIG. 6 is a graph showing the relationship between the heat pipe tilt angle and the heat transfer amount limit of the heat radiating unit in the heat radiating unit of the embodiment of FIG. 8 is a graph showing the relationship between the ratio of the short axis to the long axis of the heat pipe evaporation section and the heat radiation performance in the heat radiation unit of the embodiment of FIG. 1, and FIG. 8 shows another embodiment of the heat pipe heat radiation unit according to the present invention. 10 is a front view, FIG. 9 is an enlarged sectional view taken along the arrow BB in FIG.
Is a perspective view of a conventional heat pipe type heat dissipation unit already proposed by the inventors, FIG. 11 is a front view of the radiator of FIG. 10, and FIG. 12 is a partially enlarged cross-sectional view of the heat dissipation unit of FIG.

The heat radiating unit shown in FIG.
And a heat transfer plate 2 fixed to the evaporation part 10 which is a part of the heat pipe 1, and a large number of heat dissipation plates 3 attached to the condensation part 11 which is another part of the heat pipe 1. There is.

The heat transfer plate 2 has a length L2 = 38 mm and a width W = 3.
Aluminum alloy with 7 mm and thickness T = 3.0 mm (A606
3) a plate having a flat (or oval) cross section whose major axis R1 = 4.2 mm and minor axis R2 = 1.9 mm along the length direction such that the major axis is along one surface Pipe insertion hole 20
6 are formed at substantially uniform intervals. The heat transfer plate 2 is formed by extruding a long plate having six pipe insertion holes 20 having the above-described cross-sectional shape, and the long plate has a length of 38 mm.
It was cut into pieces.

The heat pipe 1 in which the evaporation portion 10 is inserted and fixed in each of the pipe insertion holes 20 has an outer diameter = 3 mm, a total length L1 = 128 mm, a wall thickness = 0.3 mm, and a copper-made micro liquid whose working fluid is water. It is a heat pipe and has fine grooves (not shown) formed inside along the length direction. The evaporation section 10 of the heat pipe 1 has a flat (or oval) cross section with a major axis r1 = 3.6 mm and a minor axis r2 = 1.9 mm,
Both surfaces (upper and lower surfaces in FIG. 2) along the long axis r1 are crimped so as to be substantially in close contact with the upper and lower inner wall surfaces along the long axis R1 of the pipe insertion hole 20. The condensing part 11 having a circular cross section, which is the other part of the heat pipe 1, has a size of 40 mm × 8 mm,
Forty heat dissipation plates 3 having a thickness of 0.2 mm are attached at a pitch of 2 mm.

This heat dissipating unit is attached to the lower surface of the heat transfer plate 2 by L
It is used in a state where SI and other heat-generating components not shown are in contact with each other. In the state of use, the heat of the heat-generating component is transferred to the evaporation unit 10 of the heat pipe 1 through the heat transfer plate 2 to evaporate the working liquid in the evaporation unit 10, and the condensation unit having a low internal pressure due to the vapor of the working liquid. It is carried to 11 and discharged into the air through the radiation fins 3.

The heat pipe type heat radiating unit of the embodiment shown in FIGS. 1 and 2 is manufactured by the manufacturing method described below. First, a long plate as described above is extruded and cut to manufacture a heat transfer plate 2, and as shown in FIG. 3, an evaporation unit 10 which is a part of each heat pipe 1 having a circular cross section is formed. , The major axis r3 = 4 mm and the minor axis r4 = 1.2 mm are previously formed into a flat (or oval) cross section by pressing. Next, each pipe insertion hole 2 of the heat transfer plate 2
The evaporating portion 10 of the heat pipe 1 was inserted into the heat pipe 1 such that its major axis was substantially along the major axis of the insertion hole 20. Then, the heat transfer plate 2 is attached to and restrained by a holder (not shown).
After being carried into a heating furnace (not shown) kept at 80 ° C. and held for about 30 minutes, these were carried out from the heating furnace and cooled at room temperature. Then, 40 radiating fins 3 of the above-mentioned size were attached to the condensing part 11 of the heat pipe 1 at a pitch of 2 mm to manufacture a radiating unit.

As the heat pipe 1 is heated in the heating furnace, the internal pressure increases, and the evaporating portion 10 having a flat cross section expands and expands in a direction closer to a circle, that is, in the minor axis direction as shown in FIG. The upper and lower surfaces were crimped to the upper and lower surfaces of the pipe insertion hole 20 in a substantially close contact state. When the heat pipe 1 is heated as described above, the condensing part 11 which is the other part of the heat pipe 1 and whose cross section is circular has a larger strength than the evaporating part 10 having the flat cross section, so that the condensing part 11 may rupture or expand. do not do.

As described above, both surfaces of the heat pipe 1 along the long axis of the evaporating section 10 are pipe insertion holes of the heat transfer plate 2 due to the expansion force acting from the inside along the short axis direction of the heat pipe. Since the upper and lower inner wall surfaces of the heat pipe 20 are pressure-bonded to each other in a substantially uniform contact state, the heat resistance of the pressure-bonding portion between the evaporation portion 10 of the heat pipe 1 and the inner wall surface of the insertion hole 20 of the heat transfer plate 2 is small and varies. As a result, the heat transfer performance becomes higher even if the contact area between the heat pipe 1 and the pipe insertion hole 20 of the heat transfer plate 2 is small. Further, by using a thinner heat transfer plate integrally formed, it is possible to manufacture a small and lightweight heat pipe type heat dissipation unit having higher heat transfer performance. Further, the pressure bonding between the evaporating portion of the heat pipe 1 and the inner wall of the pipe insertion hole 20 is achieved by heating the heat pipe 1, and the soldering step of the conventional manufacturing method can be omitted.
The heat pipe type heat dissipation unit is manufactured at lower cost and in large quantities.

In the heat pipe type heat radiating unit manufactured by the above-described manufacturing method, as shown in FIG. 2, both longitudinal ends of the pipe insertion hole 20 of the heat transfer plate 2 and both longitudinal ends of the evaporating portion 10. A space 22 is formed between the heat dissipation unit and the heat dissipation unit, but the space 22 does not deteriorate the heat dissipation performance in the heat dissipation unit of the above-described embodiment. However, the gap 22
For example, the solder 21 may be poured and filled as shown in FIG. The other components and sizes of each part of the heat dissipation unit of FIG. 4 are the same as those of the heat dissipation unit of FIGS. 1 and 2.

The heat dissipation unit sample 1 shown in FIGS. 1 and 2 and the heat dissipation unit sample 2 shown in FIG. 4 are manufactured, and the heat pipe evaporation unit 10 shown in FIG. Samples of four types of heat dissipation units with different ratios were manufactured, and the heat dissipation performance of the samples of each heat dissipation unit was measured. Based on this measurement result,
The ratio of the heat dissipation performance a of the heat dissipation unit of Sample 1 to the heat dissipation performance b of the heat dissipation unit of Sample 2 is represented in the vertical axis direction, and the heat dissipation performance of each of the four types of sample heat dissipation units is represented in the horizontal axis direction, It was as shown in FIG. 7. From the above measurement results, the ratio of the short axis r2 to the long axis r1 of the heat pipe evaporation unit 10 in the heat dissipation unit is 0.6.
If the minor axis r2 is 1.5 mm or more,
Both ends of the long axis of the evaporator 10 and the pipe insertion holes 20 of the heat transfer plate 2
It was found that even if the gap 22 shown in FIG.

Next, in the state shown in FIG. 3, the gap 23 between the evaporation portion 10 of each heat pipe 1 and each pipe insertion hole 20 of the heat transfer plate 2 is filled with melted Sn--Zn system solder (not shown),
A heat radiating fin similar to the heat radiating fin 3 of FIG. 1 was attached to the condensing part of the heat pipe 1 to manufacture a heat radiating unit sample 3. Then, for each of the heat dissipation units of this sample 3 and each of the samples 1 and 2, the heating element 50 is brought into contact with the heat transfer plate 2 to change the inclination angle θ of the heat pipe 1 as shown in FIG. When the heat transfer amount limit of each sample was measured while blowing air to the part, it was as shown in FIG. According to this measurement result, the heat radiation performance of the heat radiating units of Samples 1 and 2 of the present invention is 0 ° with respect to the heat radiating performance of the heat radiating unit of Sample 3 of the comparative example. When the tilt angle θ was 90 °, it was almost 5 times.

Further, when the overall heat resistance of the heat dissipation unit of each sample described above was measured, the heat resistance of the heat dissipation units of Samples 1 and 2 according to the embodiment of the present invention was as follows.
The value was about 5% lower than the thermal resistance of the heat dissipation unit of Sample 3 which is a comparative example. This is because the expanded heat pipe has a higher condensation heat transfer coefficient of 50% or more than the unexpanded heat pipe.

8 and 9 show another embodiment of the heat dissipation unit according to the present invention. The heat dissipation unit of this embodiment has a heat pipe 1 having a flat cross section as a whole, and a heat transfer plate 2 fixed to an evaporation portion 10 of the heat pipe 1.
And a heat transfer plate 4 fixed to the condensing part 11 of the heat pipe 1, and a radiation fin 30 attached to the heat transfer plate 4. The radiating fins 30 are configured almost the same as the radiating fins 30 in the radiating unit of FIG.

This heat dissipation unit is provided on the lower surface of the heat transfer plate 2,
The heat generating component 5 mounted on the substrate 7 is used in a state of being in contact with the high heat conductive rubber 6 therebetween. The heat transfer plate 2 is integrally extruded from an aluminum alloy and has a size of thickness = 3 mm, width = 100 mm, length = 180 mm, and a long axis = 6.0 mm at the center of the thickness part. , Two flat pipe insertion holes 20 having a size of minor axis = 2.0 mm are formed. The pipe insertion hole 20 is formed such that its long axis is parallel to one surface of the heat transfer plate 2. Although not shown, the other heat transfer plate 4 also has a pipe insertion hole of a similar size.

The heat pipe 1 is a flat copper pipe having a circular cross section, and the size before manufacturing the heat dissipation unit has a minor axis of 1.8 mm, a major axis of 5.8 mm and a length of 5.8 mm. = 300 mm. Each end of the heat pipe 1 is inserted into each pipe insertion hole 20 of each of the heat transfer plates 2 and 4 described above so that the long axis extends along the long axis of the pipe insertion hole 20. Then, the heat transfer plate 2 is attached to and restrained by a holder (not shown), carried into a heating furnace (not shown) kept at 180 ° C. and held for about 30 minutes, and then these are carried out from the heating furnace. And cooled at room temperature.

The heat pipe 1 having a flat cross section is heated in the heating furnace to increase the internal pressure and expands and expands in the direction in which it tends to become round, that is, in the minor axis direction.
, The upper and lower surfaces along the long axis of the pipe insertion hole 20
It is crimped to the upper and lower inner wall surfaces along the long axis of the above in a substantially close contact state. In this way, the heat transfer plate 2 is fixed to the evaporation part 10 of the heat pipe 1, and the heat transfer plate 4 is fixed to the condensation part 11 thereof. The sizes of the evaporating section 10 and the condensing section 11 in the cross section in this fixed state have a minor axis of 2.0.
mm, major axis = 5.68 mm. As described above, after fixing the heat transfer plates 2 and 4 to the evaporation part 10 and the condensation part 11 of the heat pipe 1, the heat dissipation fins 30 were attached to both surfaces of the heat transfer plate 4 to manufacture the heat pipe type heat dissipation unit. 8 and 9
According to the heat dissipation unit of the embodiment shown in FIG. 3, the heat transfer plate 4 is fixed to the condensing part 11 of the heat pipe 1, and the heat dissipation plate 30 is attached with the heat dissipation fins 30 having a larger surface area. Since the basic structure and operation of the parts are almost the same as those of the heat dissipation unit of the embodiment of FIG. 1, their description will be omitted.

In each of the above-mentioned embodiments, after the inner wall surfaces of the pipe insertion holes 20 of the heat transfer plates 2 and 4 are subjected to surface treatment such as solder plating, the heat pipe 1 is partially inserted into the pipe insertion holes 20. Then, the heat pipe 1 may be expanded by heat and pressure-bonded to the pipe insertion hole 20. In addition, after performing a surface treatment such as solder plating on the entire surface or a part of the heat pipe 1, a part of the heat pipe 1 is inserted into the pipe insertion hole 20, and the heat pipe 1 is heated and expanded to expand the pipe insertion hole 20. You may crimp to. In these cases, the solder layer is interposed between the heat pipe 1 and the upper and lower inner wall surfaces of the pipe insertion hole 20. For the above-mentioned solder, for example, Sn-Zn based solder is used.

In each of the above-described embodiments, only the example in which the heat transfer plate 2 or 4 is attached to the evaporation part 10 or the evaporation part 10 and the condensation part 11 which are a part of the heat pipe 1 has been described. Including the case where the heat transfer plate 2 and the other heat transfer plate 4 in FIG. 8 are integrated and the heat pipe 1 and the heat transfer plate 2 are fixed in a state where the entire heat pipe 1 is embedded in the heat transfer plate 2. Be done. In the heat dissipation unit having such a structure, it is preferable to attach a suitable heat dissipation fin 30 to a part of the heat transfer plate 2.

[0045]

In the heat pipe type heat radiating unit according to the present invention, both surfaces along the long axis of the evaporation portion of the heat pipe are crimped in close contact with the inner wall surface along the long axis of the pipe insertion hole of the heat transfer plate. Therefore, the heat resistance is small and the heat transfer is performed well. Further, in the heat pipe type heat dissipation unit according to the present invention, sufficient strength can be maintained even if the heat transfer plate is made thinner with a lighter material. Therefore, the entire heat dissipation unit can be made thinner and lighter.

According to the method of manufacturing the heat pipe type heat dissipation unit of the present invention, both surfaces of the heat pipe evaporation portion along the major axis are transferred from the inside by the expansion force acting along the minor axis direction of the heat pipe. It is crimped to the inner wall surface along the long axis of the pipe insertion hole formed in the hot plate in a substantially uniform close contact state. Therefore, the thermal resistance of the crimping portion between the both surfaces along the major axis of the heat pipe evaporating portion and the inner wall surface of the heat transfer plate along the major axis of the pipe insertion hole is small and almost uniform without variation. As a result, the heat transfer performance becomes higher even if the contact area between the heat pipe and the heat transfer plate is small. Therefore, it is also possible to manufacture a small and lightweight heat pipe type heat dissipation unit having higher heat dissipation performance by using an integrated thinner heat transfer plate.

According to the manufacturing method of the present invention, since the condensing portion of the heat pipe expands and expands its cross-sectional area,
The amount of heat transport increases compared to before pipe expansion. Further, in the manufacturing method according to the present invention, the heat pipe and the heat transfer plate can be fixed by a simple process of inserting a part of the heat pipe into the pipe insertion hole of the heat transfer plate and heating and expanding the heat pipe. The unit can be mass-produced at a lower cost.

[Brief description of drawings]

FIG. 1 is a partially omitted plan view showing an embodiment of a heat pipe type heat dissipation unit manufactured by a manufacturing method of the present invention.

FIG. 2 is a partially enlarged cross-sectional view taken along the arrow AA of FIG.

FIG. 3 is a partial enlarged cross-sectional view showing a state before heat-expanding the evaporation part of the heat pipe in the heat dissipation unit of FIG.

FIG. 4 is a partially enlarged sectional view showing another embodiment of the heat pipe type heat dissipation unit according to the present invention.

5 is a front view of the heat pipe type heat dissipation unit of the embodiment of FIG. 1 in a tilted state. FIG.

6 is a graph showing a relationship between a heat pipe inclination angle and a heat transfer amount limit of the heat dissipation unit in the heat dissipation unit of the embodiment of FIG.

7 is a graph showing the relationship between the ratio of the minor axis to the major axis of the heat pipe evaporation section and the heat radiation performance in the heat radiation unit of the embodiment of FIG.

FIG. 8 is a front view showing another embodiment of the heat pipe type heat dissipation unit according to the present invention.

9 is an enlarged cross-sectional view taken along the arrow BB of FIG.

FIG. 10 is a perspective view of a conventional heat pipe type heat dissipation unit already proposed by the inventors.

11 is a front view of the heat dissipation unit of FIG.

12 is a partially enlarged cross-sectional view of the heat dissipation unit of FIG.

[Explanation of symbols]

1 heat pipe 10 Evaporator 11 Condensing part 2,4 heat transfer plate 20 Pipe insertion hole 21 Solder 22,23 gap 3,30 heat radiation fin 5 heat generating parts 50 heating element 6 High thermal conductivity rubber 7 substrate 8,9 Heat transfer plate 80 body 81 Lid 82 groove 83 Solder 84 void Total length of L1 heat pipe L2 Length of heat transfer plate 2 Width of W heat transfer plate 2 Thickness of heat transfer plate 2 Long axis of R1 pipe insertion hole 20 R2 pipe insertion hole 20 short axis r1 long axis of heat pipe evaporator 10 r2 Short axis of heat pipe evaporator 10 r3 long axis before expansion of heat pipe evaporation unit 10 r4 Heat pipe evaporation unit 10 short axis before expansion θ Heat pipe tilt angle

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenzo Kobayashi 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (56) Reference JP-A-4-282857 (JP, A) JP-A 4-361561 (JP, A) JP-A-5-106977 (JP, A) JP-A-6-310888 (JP, A) JP-A-7-198279 (JP, A) Actual Kaihei 5-4495 (JP, A) U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F28D 15/02 H01L 23/427 H05K 7/20

Claims (6)

(57) [Claims] 1. A heat pipe type heat radiating unit in which one or more heat pipes are attached to a heat transfer plate, and heat is exchanged between a heat generating component of an electronic device and the heat pipe through the heat transfer plate, In the thickness portion of the heat transfer plate, a pipe insertion hole having a substantially flat or oval cross section in which a long axis is parallel to one surface of the heat transfer plate is formed, and the pipe insertion hole has at least a part of the heat pipe. Is inserted, and the inserted portion of the heat pipe inserted into the pipe insertion hole is formed such that its cross section has a substantially flat or oval shape, and both surfaces along the long axis thereof have the length of the pipe insertion hole. It is crimped to the inner wall surface along the axis in a nearly uniform contact state.
Characterized in that that, a heat pipe type heat dissipation unit. 2. The inserted portion of the heat pipe has a short axis /
The heat pipe type heat dissipation unit according to claim 1, wherein the major axis is 0.6 or less and the minor axis is 1.5 mm or more. 3. The heat pipe type heat dissipation unit according to claim 1, wherein the heat transfer plate is made of an extruded material having a thickness of 2.5 mm or more. 4. A radiating fin is provided on at least a part of a portion other than the inserted portion of the heat pipe,
The heat pipe type heat dissipation unit according to claim 1. 5. The heat pipe type heat dissipation unit according to claim 1, wherein a part of the heat transfer plate is provided with a heat dissipation fin. 6. A method of manufacturing a heat pipe type heat dissipation unit, wherein one or more heat pipes are attached to a heat transfer plate, and heat is exchanged between a heat generating component of an electronic device and the heat pipe via the heat transfer plate. In the thickness of the heat transfer plate, the pipe insertion hole having a flat or elliptical cross section in which the long axis is formed in a state where the long axis is substantially parallel to one surface of the heat transfer plate includes part or all of the heat pipe. Inserting the inserted portion having a flat or oval cross section in a state where the major axis of the inserted portion is substantially along the major axis of the pipe insertion hole; and heating the heat pipe to shorten the inserted portion. A method for manufacturing a heat pipe type heat dissipation unit, comprising the step of crimping both surfaces along the major axis of the inserted portion to the inner wall surface along the major axis of the pipe insertion hole by expanding the pipe in the axial direction.