JP2001165585A - Flat surface type heat pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat surface type heat pipe, high in a heat generating density and capable of being used for the cooling of heat generating electronic components, such as CPU, MCM, IPM or the like, and reliable in the operation of the same even when the heat pipe is installed on a transportation machine or the like under slanted condition. SOLUTION: The flat surface type heat pipe is constituted of a heat generating unit, a first condensing unit, a second condensing unit, a first intermediate unit, situated between the heat generating unit and the first condensing unit while being equipped with a first short path unit for short-cutting between the heat generating unit and the first condensing unit, and a second short path unit, situated between the heat generating unit and the second condensing unit for short-cutting between the heat generating unit and the second condensing unit, while operating fluid is sealed and closed in the heat pipe air-tightly and integrally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IPM (Intellige
nt power module), IGBT (Insulated Gate Bipolar
The present invention relates to a flat heat pipe suitable for heat radiation (cooling) of a heat-generating electronic component such as a transistor.

[0002]

2. Description of the Related Art In recent years, electronic equipment incorporates a high-output, highly integrated component such as a microprocessor. Microprocessors are extremely integrated,
Since a large amount of information is processed and controlled at high speed, a large amount of heat is released. Various cooling systems have been proposed to cool chips and the like, which are high-output and highly integrated components. One of the typical cooling systems is a heat pipe.

[0003] The heat pipes include a round pipe heat pipe and a planar heat pipe. For cooling a component to be cooled of an electronic device such as a CPU, a flat heat pipe is preferably used because it can be easily attached to the component to be cooled and a wide contact surface can be obtained.

Further, the heat pipe is divided into a top heat mode in which the component to be cooled is located at an upper position and a bottom heat mode in which the component to be cooled is located at a lower portion at a position where the component to be cooled is mounted. In the top heat mode, a normal wick is used, and in the bottom heat mode, the wick is removed. A space serving as a flow path of the working fluid is provided inside the heat pipe, and heat is transferred by the working fluid contained in the space undergoing a phase change such as evaporation and condensation or movement.

The details of a heat pipe which has a sealed cavity and transfers heat by phase transformation and movement of a working fluid contained in the cavity are as follows. On the heat-absorbing side of the heat pipe, the working fluid evaporates due to the heat generated by the component to be cooled which has been transmitted through the material of the container constituting the heat pipe, and the vapor moves to the heat radiating 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.

[0006] The working fluid that has returned to the liquid phase in this way moves (recirculates) to the heat absorbing side again. Heat transfer is performed by such phase transformation and movement of the working fluid. In a gravity-type heat pipe, the working fluid in a liquid phase state due to the phase transformation moves (refluxes) to the heat-absorbing side by gravity or capillary action.

Japanese Patent Application Laid-Open No. 9-119788 discloses a flat heat pipe having a heat generating portion and a condensing portion (hereinafter referred to as "prior art"). FIG. 7 shows an outline of the flat heat pipe. As shown in FIG. 7, the prior art flat heat pipe has a panel body having an evaporator 20, a condenser 21, and a heat pipe circuit 23 connecting the evaporator 20 and the condenser 21 and circulating a working fluid. The evaporator 20 has a plate 22 on which a heating element such as an electronic component is placed, and the condenser 21 has fins. A working fluid is sealed in the heat pipe circuit 23 described above.

Further, as shown in FIG. 7, the prior art flat heat pipe is an L-shaped or inverted L-shaped flat heat pipe, and the evaporating section 20 and the condensing section 21 are connected at a right angle. Heat released from a heating element such as an electronic component which is conducted through a plate 22 which is in close contact with the evaporator 20 is passed through a heat pipe circuit 23 by a working fluid to a condenser 21.
And dissipates heat into the air through fins that are in close contact with the condenser.

[0009]

However, the prior art flat heat pipe has the following problems. That is, as described above, the prior art flat heat pipe is an L-shaped or inverted L-shaped flat heat pipe, and the evaporating unit 20 and the condensing unit 21 are connected at a right angle. That is, the heat pipe circuit 23 has a right-angled corner. Therefore, both the steam flow of the working fluid that has become steam in the evaporating section and the working fluid stream that is condensed and circulated in the condensing section are forced to switch from the horizontal direction to the vertical direction or from the vertical direction to the horizontal direction. There is a problem that it is difficult to ensure a smooth flow of the fluid and / or the working fluid.

In particular, when the heating element is mounted at a high position in the vertical direction of the evaporating section, it is necessary to raise the level of the working fluid for cooling the heating element. However, when the level of the hydraulic fluid is increased, the steam flow path and the return flow path of the hydraulic fluid become narrower, the flow path resistance increases, and smooth heat transport becomes difficult.
The thermal resistance increases and the thermal performance of the heat pipe decreases.

Further, when the heat pipe is installed on a transport machine or the like, there is a state where the heat pipe is inclined and the heat generating portion of the heat pipe is higher than the condensing portion. In addition, it becomes difficult to secure a return flow path for the working fluid, and efficient heat transport cannot be performed. As a result, the thermal resistance increases and the thermal performance of the heat pipe decreases.

Therefore, an object of the present invention is to provide a heat pipe having a high heat density, which can be used to cool heat-generating electronic components such as CPU, MCM, and IPM. Another object of the present invention is to provide a flat heat pipe whose operation is reliable.

[0013]

Means for Solving the Problems The present inventor has made intensive studies to solve the above-mentioned conventional problems. as a result,
At the corner between the heat generating part and the condensing part of the L-shaped or inverted L-shaped flat heat pipe, by providing a short path part for short-circuiting between the heat generating part and the condensing part, it becomes vapor in the evaporating part. A passage for a steam flow through which the working fluid passes,
A passage for the working fluid flow which is condensed and recirculated in the condenser section can be secured respectively, so that a smooth flow of the steam flow and the working fluid flow can be secured, and a plane having high thermal performance and reliable in its operation. It has been found that a mold heat pipe can be provided.

Furthermore, if condensing parts are provided on both sides of the heat generating part as a center, even if the heat generating part of the heat pipe is installed higher than one condensing part in a transport machine or the like, the other condensing part is provided. Since a state higher than the heat generating portion can be secured, a passage for the steam flow through which the working fluid that has been vaporized in the evaporating portion passes, and a passage for the working fluid flow which is condensed and circulated in the condensing portion are secured. , Which can ensure smooth flow of steam flow and working fluid flow, and have high thermal performance,
It has been found that a flat heat pipe whose operation is reliable can be provided.

[0015] The present invention has been made based on the above findings, and a first aspect of the flat heat pipe of the present invention is a heat pipe, a first condenser, and a second condenser. ,
A first intermediate portion between the heat generating portion and the first condensing portion, the first intermediate portion including a first short path portion for shortcut between the heat generating portion and the first condensing portion; and A second intermediate portion between the heat generating portion and the second condensing portion, the second intermediate portion including a second short path portion for short-circuiting between the heat generating portion and the second condensing portion. This is a flat heat pipe in which a working fluid is sealed, hermetically sealed, and integrally formed.

In another aspect of the flat heat pipe of the present invention, the heat generating portion extends in one direction, the first and second condensing portions extend in a direction perpendicular to the one direction and in the same direction, and The first short path section linearly short-circuits between the heat generating section and the first condenser section, and the second short path section includes the heat generating section and the second condensing section.
And a straight line shortcut between the condensing part.

According to another aspect of the flat heat pipe of the present invention, the heat generating portion extends in one direction, the first and second condensing portions extend in a direction perpendicular to the one direction and in the same direction, and The first short path section curvilinearly short-circuits between the heating section and the first condensing section, and the second short path section includes the heating section and the second condensation section.
And a short-circuit between the condensing part and the condensing part.

In another aspect of the planar heat pipe of the present invention, the first short path portion and the second short path portion each have a working fluid passage having substantially the same width. It is a feature.

According to another aspect of the flat heat pipe of the present invention, the first short path portion and the second short path portion are respectively formed from the heat generating portion to the first intermediate portion or the first short path portion. The passage for the working fluid expands to the middle part of the second and said first middle part, or
From the second intermediate section to the first condensing section or the second
The passage for the working fluid is reduced toward the condensing section.

According to another aspect of the flat heat pipe of the present invention, the first short path section and the second short path section each have a separate passage for a steam flow from the heat generating section. It is characterized by having.

Another aspect of the flat heat pipe of the present invention is characterized in that the flat heat pipe is embossed.

Another aspect of the flat type heat pipe according to the present invention is that a heat generating portion and a first heat pipe disposed above the heat generating portion.
And a second condensing section disposed below the heat generating section. A working fluid is sealed in the inside of the condensing section, and the flat heat pipe is integrally formed.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the flat heat pipe of the present invention will be described in detail. The flat heat pipe of the present invention comprises a closed container having an upper plate 15 and a lower plate 16. The sealed container thus prepared is crushed from above and below with a mold to form the emboss 9. FIG. 5 shows a cross-sectional view of a flat heat pipe having an emboss formed thereon. A flow path 17 is secured between the upper plate 15 and the lower plate 16, and a working fluid is sealed in the flat heat pipe.

As shown in FIG. 5, the emboss thus formed has a function of preventing the container from being deformed due to an increase in the internal pressure in accordance with the rise in the temperature of the internal fluid. Furthermore, the flat heat pipe of the present invention can also be manufactured by a roll bonding method. Further, the periphery may be formed by welding or the like.

The container is made of a heat conductive material,
Examples of the heat conductive material include copper, aluminum, steel, stainless steel, nickel, tungsten, tantalum, niobium alloy, inconel, titanium, glass, and ceramics. Among them, copper and aluminum are suitable. Working fluids include water, CFC substitute, acetone, methanol,
Helium, nitrogen, ammonia, Dowsome A, naphthalene, cesium, sodium, lithium, silver and the like can be used.

FIG. 1 is a view schematically showing one embodiment of the flat heat pipe of the present invention. The flat heat pipe 1 of the present invention is provided between the heat generating part 2, the first condensing part 3, the second condensing part 4, the heat generating part 2 and the first condensing part 3, and the heat generating part A first intermediate portion 5 having a first short path portion 7 for short-circuiting between the first intermediate portion 5 and the first condensing portion;
And a second intermediate portion 6 provided between the heat generating portion 2 and the second condensing portion 4 and having a second short path portion 8 for short-circuiting between the heat generating portion and the second condensing portion. And a working fluid is sealed therein, hermetically sealed, and integrally formed. First condenser 3
The fin 10 is attached to the second condensing section 4. The heat generating portion 2 is provided with a heat generating member mounting portion (portion indicated by oblique lines) to which a heat generating member is mounted.

In the flat heat pipe 1 of the present invention, the heat generating portion 2 extends in one direction, for example, in the horizontal direction, and the first condensing portion and the second condensing portion are each in a direction perpendicular to the above-described one direction. For example, it extends vertically to form a U-shape. The first short path section and the second short path section linearly short-circuit between the heat generating section and the first condensing section and the second condensing section, respectively, as shown in FIG. 1, for example. .

Further, in the flat heat pipe of the present invention, the above-mentioned short path portion is provided as shown in FIG.
A curvilinear shortcut may be provided between the heat generating section and the first and second condenser sections. In the flat heat pipe of the present invention, as shown in FIGS. 1 and 2, the first short path portion and the second short path portion each have a working fluid passage having substantially the same width. Is also good.

Further, the shapes of the shortcut parts 7 and 8 are as follows.
In addition to the above, it is sufficient that the steam flow path and the return flow path of the working fluid are enlarged in the shortcut portion.
That is, as shown in FIG. 3, the first short path portion and the second short path portion each have a passage for the working fluid, for example, a straight line from the heat generating portion to the first intermediate portion and the second intermediate portion. From the first intermediate portion and the second intermediate portion to the first condensing portion and the second condensing portion, respectively, the passages for the working fluid are, for example, linearly reduced. You may.

In the flat heat pipe of the present invention,
The first short path section and the second short path section described above may each include a separate passage for the steam flow from the heating section. That is, the steam flow path for the steam flow and the working fluid recirculation flow path for the working fluid may be composed of separate passages. FIG. 4 is a diagram illustrating one embodiment of the planar heat pipe of the present invention with separate passages for the steam flow. In the case where the steam flow path and the working fluid recirculation flow path are separated to provide separate passages, FIG.
As shown in the figure, form a triangular cutout in the middle,
A steam flow path and a working fluid recirculation flow path may be configured.

As shown in FIG. 6, the flat heat pipe according to the present invention has a heating section 2, a first condenser section 3 disposed above the heating section, and a second condenser section 3 disposed below the heating section. And a working fluid may be sealed therein, hermetically sealed, and integrally formed.

Further, in the flat heat pipe according to the present invention, when the heat-generating portion is arranged in the horizontal direction and the condensing portion is arranged in the vertical direction, the angle of the short-cut portion with the horizontal direction of the short-cut portion is 15-. It is preferably 50-.

Further, the flat heat pipe of the present invention is
It is preferable to use it installed at an angle in the range of 30 to 90 from the horizontal plane. Further, the fins may be fixed to the flat heat pipe of the present invention by brazing or screws.

As is apparent from the above description, in the flat heat pipe having the short path section of the present invention, heat is efficiently transferred from the evaporating section to the condensing section. It can be seen that the recirculation of the working fluid to the evaporating section is performed smoothly.

According to the flat heat pipe of the present invention,
Since a short path section that provides a shortcut between the heat generating section and the condensing section is provided in the intermediate section, a sufficiently large steam flow path and a return flow path for the working fluid can be secured, and the flow path resistance is reduced. Increases thermal performance and enables smooth heat transport. Therefore, the flat heat pipe of the present invention has
It is suitable for cooling heat-generating electronic components such as PM and IGBT.

[0036]

EXAMPLE 1 As shown in FIG. 1, an upper plate and a lower plate each made of an aluminum plate having a thickness of 1 mm formed a straight line between the heat generating portion and the first and second condensing portions. A container having a first short path portion and a second short path portion, which were short-cut, was formed, and embossed with a press die. Then, vacuum was drawn to produce a flat heat pipe in which alternative Freon was sealed as a working fluid.

The edges were brazed. The respective sizes at that time were as follows. Vertical height of heat pipe: 300mm, height of short path: 4
0 mm, inclination angle of the short path section: 45 degrees, horizontal length of the heat pipe: 250 mm, width of the heating section: 50 m
m, width of the condensing part: 50 mm. The thickness of the flat heat pipe manufactured as described above was 4 mm.

When the flat heat pipe manufactured as described above was applied to the cooling of the IGBT while being moved clockwise and counterclockwise around the heat generating portion, the IGBT was cooled.
The heat generated from the heat was effectively transferred, and a good cooling effect was obtained. As a result, it can be seen that heat can be efficiently transported even in a state where the heat pipe is inclined when installed on a transport machine or the like.

Embodiment 2 As shown in FIG. 2, an upper plate and a lower plate each made of an aluminum plate having a thickness of 1 mm respectively form a curved portion between the heat generating portion and the first condensing portion and the second condensing portion. To form a container having a first short path portion and a second short path portion, which were short-circuited, and embossed with a press die. Then, vacuum was drawn to produce a flat heat pipe in which alternative Freon was sealed as a working fluid.

The respective sizes at that time were as follows. Vertical height of heat pipe H: 300m
m, height of short path section: 40 mm, radius of curvature of short path section: 50 mm, horizontal length of heat pipe: 250 mm, width of evaporating section: 50 mm, width of condensing section:
It was 50 mm. The thickness of the flat heat pipe manufactured as described above was 4 mm.

When the flat heat pipe manufactured as described above was applied to cooling of the IGBT while being moved clockwise and counterclockwise around the heat generating portion, the IGBT was cooled.
The heat generated from the heat was effectively transferred, and a good cooling effect was obtained. As a result, it can be seen that heat can be efficiently transported even in a state where the heat pipe is inclined when installed on a transport machine or the like.

COMPARATIVE EXAMPLE 1 As shown in FIG. 7, an inverted L-shaped container in which the heat generating portion and the condensing portion are connected at right angles by an upper plate and a lower plate each made of an aluminum plate having a thickness of 1 mm. Formed and embossed with a press mold. Then, vacuum was drawn to produce a flat heat pipe in which water was sealed as a working fluid.

The respective sizes at that time were as follows. Vertical height of heat pipe: 300mm,
The length of the heat pipe in the horizontal direction was 250 mm, the width of the evaporator was 50 mm, and the width of the condenser was 50 mm. The thickness of the flat heat pipe manufactured as described above was 4 mm.

When the flat heat pipe manufactured as described above was applied to cooling of an IGBT, there was a local temperature rise in the heat generating portion. Further, as in the example, when the heat pipe was inclined and applied to the cooling of the IGBT, the temperature of the heat generating portion increased remarkably. The sizes of the heat pipes described in the embodiments, such as the width and the length, are shown as specific examples, and are not limited thereto.

As described above, the conventional L-shape or
According to the inverted L-shaped flat heat pipe, the steam flow and the return liquid flow are not smooth, the heat resistance is large, and the desired cooling effect cannot be obtained. According to the heat pipe, by providing a short path portion for short-circuiting between the heat generating portion and the condensing portion at a corner between the heat generating portion and the condensing portion of the L-shaped or inverted L-shaped planar heat pipe, the evaporation can be achieved. A passage for the steam flow through which the working fluid that has become the vapor passes in the section, and a passage for the working fluid flow that is condensed and circulated in the condensing section are secured, respectively, to ensure a smooth flow of the steam flow and the working fluid flow. As a result, a flat heat pipe having high thermal performance and reliable operation was obtained.

Further, the flat heat pipe is moved clockwise and counterclockwise about the heat generating portion so that even when the heat pipe is inclined, a steam flow through which the working fluid vaporized in the evaporating portion passes. A passage and a passage for the working fluid flow which is condensed and recirculated in the condenser section can be secured respectively, so that a smooth flow of the steam flow and the working fluid flow can be secured, and the operation has high thermal performance. Thus, a flat heat pipe having good quality was obtained.

[0047]

As described above, according to the present invention, even in a state where the heat pipe is inclined, the working fluid which has been vaporized in the evaporating section passes through the passage for the steam flow, and is condensed and circulated in the condensing section. It is possible to provide a flat heat pipe having a high thermal performance and a reliable operation thereof by securing a passage for the working fluid flow and a smooth flow of the steam flow and the working fluid flow, respectively. Yes, IPM,
Can be used to cool heat-generating electronic components such as IGBTs,
High industrial utility value.

[Brief description of the drawings]

FIG. 1 is a view showing one embodiment of a flat heat pipe of the present invention.

FIG. 2 is a view showing another embodiment of the flat heat pipe of the present invention.

FIG. 3 is a view showing another embodiment of the flat heat pipe of the present invention.

FIG. 4 is a view showing another embodiment of the flat heat pipe of the present invention.

FIG. 5 is a view showing a cross section of the flat heat pipe of the present invention.

FIG. 6 is a view showing another embodiment of the flat heat pipe of the present invention.

FIG. 7 is a view schematically showing a conventional inverted L-shaped flat heat pipe.

[Explanation of symbols]

 1. Flat heat pipe 2. Heating part 3. First condenser section 4. Second condensing section5. First intermediate part 6. Second intermediate part 7. First short pass section 8. Second short pass section 9. Emboss 10. Fin 15. Upper plate 16. Lower plate 17. Flow path 20. Evaporation section 21. Condensing section 22. Plate 23. Heat pipe circuit 24. Panel body

Claims (1)

[Claims] 1. A heating section, a first condenser section, a second condenser section, and between the heating section and the first condenser section,
A first intermediate portion having a first short path portion that shortcuts between the heat generating portion and the first condensing portion, and between the heat generating portion and the second condensing portion, A working fluid is sealed, sealed and integrally formed of a second intermediate portion having a second short path portion that shortcuts between the heat generating portion and the second condensing portion. The formed flat heat pipe.