JP2009076622A - Heat sink and electronic apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat sink that can convey much heat by continuously using evaporation heat, is applicable to cool a big calorific value with a simple structure, and reduces production costs, as well as an electronic apparatus using the same. <P>SOLUTION: A heat sink 4 installs upright two or more cooling fins for releasing heat from a heating element, wherein at a fin installation part 4B of the heat sink, there is provided a heat transfer substrate portion composed of a high heat-conductive metallic material, which consists of a heat transfer substrate 1 for installing a heating element 5 and a middle plate 2 for forming an activating liquid tank 3. On a concave surface portion 10 provided at the back of the heating element installation surface of the heat transfer substrate 1, there is provided a planar wick 6 formed so that capillary tube force may occur mainly in a vertical direction. Further, an evaporator 7 for the activation liquid is formed by covering the middle plate 2 opposed to the concave surface portion 10 of the heat transfer substrate 1. Moreover, the middle plate 2 has a concave surface portion 11 on a surface opposite to the surface side in contact with the heat transfer substrate 1, and by covering this concave surface portion 11 with the fin installation part 4B, the activation liquid tank 3 is formed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electronic device having a heating element such as a power device, and more particularly to a heat sink formed inside a heat pipe excellent in cooling capability and an electronic device using the heat sink.

Conventionally, heat sinks incorporating heat pipes for cooling heat generated in, for example, power devices (heating elements such as IGBTs and diode modules) used in electronic devices are as shown in FIGS. 8 is an overall perspective view of a heat sink provided with a heat pipe used in a conventional electronic device, FIG. 9 is a side sectional view of FIG. 8, and these cooling devices have already been filed by the present applicant ( For example, see Patent Document 1).
8 and 9, 1 is a heat transfer substrate, 30 is a pipe mounting groove, 31 is a circular pipe, 3 is a hydraulic fluid tank, 4 is a heat sink, 4A is a cooling fin, 4B is a fin mounting portion, and 5 is a heating element. .
As shown in FIGS. 8 and 9, in the heat sink 4 in which a plurality of cooling fins 4 </ b> A for radiating the heat from the heating element 5 are erected, the fin mounting portion 4 </ b> B of the heat sink 4 has a metal with high thermal conductivity. A heat transfer substrate 1 made of a material and enclosing a working fluid is provided. The heat transfer substrate 1 is embedded in the heating element mounting surface side of the substrate 1 and has a circular pipe 31 having a wick that constitutes a working fluid evaporation portion, and a tip portion of the pipe on the back side of the circular pipe 31. And a hydraulic fluid tank 3 that constitutes a hydraulic fluid condensing part that is formed in a concave groove shape so as to be exposed to the fin mounting part 4B. 1 is covered with the fin mounting portion 4B and integrated by brazing so as to maintain airtightness.
Regarding the assembly of the cooling device, first, a circular pipe 31 is embedded in a pipe mounting groove 30 formed on the surface on which the heating element 5 is mounted on the heat transfer substrate 1, and the opposite side of the heat transfer substrate 1 to the heating element mounting surface. A hole to be the hydraulic fluid tank 3 is processed into a groove shape on the surface. As shown in FIG. 9, the circular pipe 31 has a wick inside, and the tip portions at both ends are curved, and the straight line 0 portion excluding the curved portion of the circular pipe 31 is flush with the surface of the heat transfer substrate 1. Installed. Subsequently, the exposed portion of the concave groove shape of the hydraulic fluid tank 3 is covered with the heat sink fin mounting portion 4B, and the mating surfaces of the heat transfer substrate 1 and the heat sink fin mounting portion 4B are brazed to be integrated. ing.
Next, the operation will be described.
In the state where the cooling device having the above structure is installed as shown in FIG. 8, the heat from the heating element 5 is transmitted to the heat transfer substrate 1, and the heat transferred to the heat transfer substrate 1 heats the circular pipe 31. The hydraulic fluid held in the wick of the circular pipe 31 evaporates, and the steam moves to the hydraulic fluid tank 3 side due to the pressure difference. This vapor releases heat to the heat sink 4 covering the hydraulic fluid tank 3 and returns to the liquid. The heat of the heat sink 4 is transmitted to the cooling fin 4A and released to the atmosphere. The hydraulic fluid recirculates again into the circular pipe 31 by the wick capillary force and becomes steam.
Thus, since this cooling device made the circular pipe 31 and the hydraulic fluid tank 3 communicate, and constituted the heat pipe as the heat transfer substrate 1 as a whole, the hydraulic fluid was moved from the circular pipe 31 on the surface of the heat transfer substrate 1 to the hydraulic fluid tank on the back. By flowing and circulating to 3, heat of evaporation can be continuously utilized due to the temperature difference between the heat transfer substrate in contact with the heating element and the heat sink in contact with the outside air, so that a large amount of heat can be carried.
Japanese Patent Application No. 2006-144957 (Specifications, pages 2 to 3, FIG. 1)

However, in the prior art, cooling is performed by a linear heat pipe. However, if the number of heat pipes is small with respect to the heat generation amount, sufficient cooling cannot be expected. On the other hand, if a large number of heat pipes are installed, sufficient cooling can be expected, but this increases the cost.
In particular, when the electronic device is large and generates a large amount of heat, the size of the heat pipe increases, and the number of pipes used increases, resulting in structural complexity and a problem in manufacturing costs.
The present invention was made to solve the above problems, and by configuring a loop type heat pipe using a wick installed in a planar shape inside a heat transfer substrate of a heat sink in contact with a heating element, A heat sink that can continuously transport a large amount of heat using the heat of evaporation, can be applied to cooling a large amount of heat with a simple structure, and can reduce manufacturing costs, and an electronic device using the heat sink The purpose is to provide.

In order to solve the above problems, the heat sink of the present invention is configured as follows.
The invention of claim 1 is a heat sink in which a plurality of cooling fins for radiating heat from a heating element are erected, and the fin mounting portion of the heat sink is made of a metal material having high thermal conductivity, A heat transfer substrate portion in which a working fluid is enclosed is provided, and the heat transfer substrate portion constitutes a loop heat pipe having a planar wick and a hydraulic fluid tank, and the heat transfer substrate portion Is covered with the fin mounting portion, and is hermetically sealed by being integrated by brazing.

  According to a second aspect of the present invention, in the heat sink according to the first aspect, the heat transfer substrate portion includes a heat transfer substrate to which the heat generating body is attached and a concave surface portion formed on the back side of the heat generating body mounting surface of the heat transfer substrate. A flat wick provided on the intermediate plate, an intermediate plate provided to cover and cover the concave surface portion of the heat transfer substrate, and a surface opposite to the contact surface side of the intermediate plate with the heat transfer substrate. A hydraulic fluid tank formed by covering the concave surface portion with the fin mounting portion, and the wick portion and the hydraulic fluid tank communicate with each other through a hole provided at the top and bottom of the intermediate plate. It is characterized by becoming.

  According to a third aspect of the present invention, in the heat sink according to the first aspect, the heat transfer substrate portion is installed in a heat transfer substrate to which the heat generating body is attached, and a concave surface portion on the back side of the heat generating body mounting surface of the heat transfer substrate. And a hydraulic fluid tank positioned between the wall surface of the wick set installed in the concave surface portion larger than the thickness of the wick set and the fin mounting portion is provided above and below the wick set. It is characterized in that a loop-type heat pipe is formed by communicating with the wick portion through a hole provided in the.

  According to a fourth aspect of the present invention, in the heat sink according to the third aspect, the wick set is provided with a plurality of grooves in the vertical direction on a wick base made of a flat plate-like metal material having high thermal conductivity, and an elongated wick is disposed in the groove. In addition, holes are formed above and below the gap between the wicks of the wick base so as to be a passage for the working fluid and steam to be a component of the loop heat pipe.

  A fifth aspect of the present invention is an electronic device including the heat sink according to any one of the first to fourth aspects.

As described above, the embodiment of the present invention has the following effects.
According to the invention of claim 1, in the heat sink comprising a plurality of cooling fins for radiating heat from the heating element, the fin mounting portion of the heat sink is made of a metal material having high thermal conductivity, A heat transfer substrate portion in which a working fluid is enclosed is provided, and has a planar wick and a hydraulic fluid tank to constitute a loop heat pipe as a whole, and the heat transfer substrate portion is attached to the fin Since the airtightness is maintained by being integrated by brazing, the hydraulic fluid in the heat transfer board part evaporates with the heat of the heating element, and the vapor covers the heat transfer board part. After cooling and condensing, it evaporates again with the heat of the heating element. Thus, since the wick is provided in a planar shape in the heat transfer substrate portion, the entire surface of the heat transfer substrate can be cooled uniformly.

  According to a second aspect of the present invention, in the heat sink according to the first aspect, the heat transfer substrate portion comprises a heat transfer substrate to which a heat generating body is attached and an intermediate plate forming a hydraulic fluid tank, and the heat generating body of the heat transfer substrate. The back side of the mounting surface is concave and a flat wick is provided, and the intermediate plate is processed into a working fluid tank by forming a concave surface on the opposite side of the contact surface with the heat transfer substrate and covering it with a fin mounting part. The wick part and the hydraulic fluid layer communicate with each other through the holes provided above and below to form a loop heat pipe in which the evaporation part and the condensation part are separated, and carry a large amount of heat continuously using the evaporation heat Can do.

  According to invention of Claim 3, the said heat-transfer board | substrate part consists of the wick set installed in the concave part of the heat transfer board which attaches a heat generating body, and the heat generating body attachment surface of the said heat-transfer board, The hydraulic fluid tank consisting of the wall surface of the wick group and the fin mounting part installed in the concave part deeper than the thickness of the wick group communicates with the wick part through the holes provided at the top and bottom of the wick group, and the evaporation part and the condensation part are separated. It constitutes a loop heat pipe and can carry a large amount of heat continuously using the heat of evaporation.

  According to a fourth aspect of the present invention, the wick set is provided with a plurality of grooves in the vertical direction on a wick base made of a metal material having a plate-like high thermal conductivity, and an elongated wick is disposed in the groove. Since a hole is made above and below the gap between the working fluid and steam to become a component of the loop heat pipe, the transport amount of the working fluid can be changed depending on the thickness of the wick, so the optimum cooling capacity A cooler can be obtained.

  According to the fifth aspect of the invention, the electronic device having the heating element includes the heat sink with the heat pipe having the best cooling capacity as in the first to fourth aspects. A large amount of heat can be carried and dissipated in accordance with an increase in the amount of heat generated by a heating element of a power device (IGBT, diode module, etc.), and can always be operated accurately.

  Embodiments of the present invention will be specifically described below with reference to the drawings.

1 is a side sectional view of a heat sink provided with a heat pipe used in an electronic apparatus according to a first embodiment of the present invention, FIG. 2 is a sectional view taken along the line AA in FIG. 1, and FIG. 3 is an exploded view of FIG. It is a perspective view. Note that the description of the same constituent elements of the present invention as those of the prior art will be omitted, and only different points will be described.
1-3, 1 is a heat transfer substrate, 2 is an intermediate plate, 3 is a hydraulic fluid tank, 4 is a heat sink, 4A is a cooling fin, 4B is a fin mounting portion, 5 is a heating element, 6 is a planar wick, 7 Is an evaporating portion, 8 is an upper hole provided in the intermediate plate, 9 is a lower hole provided in the intermediate plate, 10 is a concave portion on the back side of the heat transfer substrate 1, and 11 is a concave surface portion on the back side of the intermediate plate 2. .
In the heat sink of FIGS. 1 to 3, the heat transfer substrate portion includes a heat transfer substrate 1 to which the heating element 5 is attached and an intermediate plate 2 that forms the hydraulic fluid tank 3. The back side of the heating element mounting surface of the heat transfer substrate 1 has a concave surface portion 10 processed into a concave surface, and a flat wick 6 is provided on the concave surface portion 10, and the wick 6 twists a metal thin wire. In addition, capillary force is mainly generated in the vertical direction. Further, the working liquid evaporation portion 7 is formed by covering the intermediate plate 2 so as to face the concave surface portion 10 of the heat transfer substrate 1. Further, the intermediate plate 2 has a concave surface portion 11 in which the opposite surface on the contact surface side with the heat transfer substrate 1 is processed into a concave surface, and the hydraulic fluid tank 3 is covered by covering the concave surface portion 11 with the fin mounting portion 4B. It comes to form. The hydraulic fluid is sealed in the hydraulic fluid tank 3 so that the evaporator 7 and the hydraulic fluid tank 3 communicate with each other through holes 8 and 9 provided on the upper and lower sides of the intermediate plate 2 to form a loop heat pipe. It has become.

Next, operation | movement of this cooling device is demonstrated based on FIG.
In the cooling device having the above-described structure and containing an appropriate amount of working fluid, the heat from the heating element 5 is transmitted to the heat transfer substrate 1 of the heat transfer substrate portion, and the heat transferred to the heat transfer substrate 1 passes through the wick 6. When heated, the hydraulic fluid held in the wick 6 evaporates, and the steam moves to the hydraulic fluid tank 3 through the hole 8 formed above the intermediate plate 2.
This vapor releases heat to the heat sink 4 covering the hydraulic fluid tank 3 and returns to the liquid. The heat of the heat sink 4 is transmitted to the cooling fin 4A and released to the atmosphere. The working fluid passes through a hole 9 formed below the intermediate plate 2 and is refluxed by the capillary force of the wick 6, and is stored again in the wick 6 to be vaporized by heat.
In the cooling device according to the first embodiment of the present invention, the evaporation section 7 provided with the planar wick and the hydraulic fluid tank 3 are communicated with the upper and lower holes 8 and 9 provided in the intermediate plate 2 as the entire heat transfer substrate section. Since the loop heat pipe is configured, the hydraulic fluid flows from the back surface of the heat transfer substrate 1 of the heat transfer substrate portion to the hydraulic fluid tank 3, so that the heat transfer substrate portion in contact with the heating element 5 and the heat sink 4 in contact with the outside air A large amount of heat can be transported by continuously utilizing the heat of evaporation due to the temperature difference between the two.
In addition, the wick used in the cooling device is formed in a flat shape so that capillary force is generated mainly in the vertical direction by twisting fine metal wires, and is arranged over the entire width of the heat transfer substrate. The entire surface of the board can be cooled uniformly, and even if the size of the heat transfer board changes depending on the size of the heating element, it is only necessary to change the size of the flat wick. Therefore, it is possible to provide an optimal cooler that has a simple structure and is easy to embed.
In addition, this cooling device does not require a structure in which a plurality of linear heat pipes are embedded in a heat sink as in the conventional case, and a simple configuration in which a flat wick is installed in a heat transfer board is sufficient. Therefore, the manufacturing cost can be reduced.

Next, a second embodiment of the present invention will be described.
4 is a side sectional view of a heat sink provided with a heat pipe used in an electronic device showing a second embodiment of the present invention, FIG. 5 is a sectional view taken along line AA in FIG. 4, and FIG. FIG. 7 is an exploded perspective view, and FIG. 7 is a perspective view of a wick set used in this embodiment.
4-7, 1 is a heat transfer board, 3 is a hydraulic fluid tank, 4 is a heat sink, 4A is a cooling fin, 4B is a fin mounting part, 5 is a heating element, 20 is a wick set, 21 is a wick base, 22 is Wick 23 is an upper hole provided in the wick base, and 24 is a lower hole provided in the wick base.
4 to 6, the back side of the heating element mounting surface of the heat transfer substrate 1 is processed into a concave surface, and the wick set 20 is installed by brazing or the like so that the wick surface is in contact with the concave surface of the heat transfer substrate 1. Is done. The concave surface portion of the heat transfer substrate 1 is deeper than the thickness of the wick set 20, and the heat transfer substrate 1 containing the wick set 20 is covered with the heat sink 4, so that a space is formed between the wick set 20 and the fin mounting portion 4B of the heat sink. The space is formed as a hydraulic fluid tank 3 in which the hydraulic fluid is accumulated.
In the hydraulic fluid tank 3, by enclosing the hydraulic fluid, the evaporating section 7 and the hydraulic fluid tank 3 communicate with each other through holes 23 and 24 provided above and below the wick base 21 to form a loop heat pipe.

Next, the wick group 20 will be described.
FIG. 7 is a perspective view of the wick set used in the second embodiment. The wick set 20 is integrated by a method such as brazing by arranging wicks 22 in a plurality of grooves of a wick base 21 made of a metal material having high thermal conductivity. The wick 22 is formed by twisting metal thin wires so that the cross-sectional shape is square or round, and the capillary force is generated mainly in the longitudinal direction.
Between the wick of the wick base 21, holes 23 and 24 are provided on the upper and lower sides. When the wick set 20 is installed in the heat transfer substrate, the evaporation unit 7 and the hydraulic fluid tank 3 are communicated to form a loop heat pipe as the entire heat transfer substrate unit.

Next, the operation of the cooling device will be described with reference to FIGS.
In the cooling device having the above-described structure and containing an appropriate amount of working fluid, the heat from the heating element 5 is transmitted to the heat transfer substrate 1 and the wick 22 of the wick set 20 installed on the concave surface portion of the heat transfer substrate 1. , The hydraulic fluid held in the wick 22 evaporates, and the steam moves to the hydraulic fluid tank 3 side from the hole 23 formed above the wick base 21 through the evaporation portion 7 in the gap between the wicks 22. To do. This vapor releases heat to the heat sink 4 covering the hydraulic fluid tank 3 and returns to the liquid. The heat of the heat sink 4 is transmitted to the cooling fin 4A and released to the atmosphere. The hydraulic fluid flows back through the hole 24 formed in the lower portion of the wick base by the capillary force of the wick, and is stored again in the wick to be vaporized by heat.

In the cooling device according to the second embodiment of the present invention, the wick set 20 including the planar wick base 21 and the wick 22 is provided in the heat transfer substrate portion, and the evaporation section 7 and the hydraulic fluid tank 3 divided by the wick set 20 are provided. Since the loop type heat pipe is configured as the entire heat transfer substrate part by communicating with the upper and lower holes, the hydraulic fluid flows from the back 22 surface of the heat transfer substrate 1 to the hydraulic fluid tank 3, thereby contacting the heat transfer body. Due to the temperature difference between the heat substrate and the heat sink in contact with the outside air, a large amount of heat can be carried using the heat of evaporation continuously.
In addition, this cooling device is easy to use without the hassle of embedding pipes as in the conventional example because the size of the heat transfer substrate changes depending on the size of the heating element, so that the size of the planar wick can be changed. An optimal cooler can be provided.
In addition, this cooling device does not need to adopt a structure in which a plurality of linear heat pipes are embedded in a heat sink as in the prior art, and a wick set consisting of a planar wick base and wick is formed in the heat transfer substrate. Since a simple configuration is required, the production cost can be reduced.
In addition, holes 23 and 24 are provided above and below the wick base for communication between the evaporation section and the hydraulic fluid tank, but in order to further increase the communication area, a heat transfer substrate is formed above and below the wick base as shown in FIG. The gaps 25 and 26 may be provided.

  The present invention provides a wick and a hydraulic fluid tank provided in a flat shape on the heat transfer substrate part, has a structure in which the hydraulic fluid can be recirculated, constitutes a loop type flat plate heat pipe as a whole, and uses evaporation heat to simplify Although it has a simple structure, it can cool a large amount of heat and is useful for cooling an electronic device suffering from an increased amount of heat.

It is a sectional side view of the heat sink provided with the heat pipe used for the electronic device which shows 1st Example of this invention. It is sectional drawing which follows the AA line of FIG. FIG. 2 is an exploded perspective view of FIG. 1. It is a sectional side view of the heat sink provided with the heat pipe used for the electronic device which shows 2nd Example of this invention. It is sectional drawing which follows the AA line of FIG. FIG. 5 is an exploded perspective view of FIG. 4. It is a perspective view of the wick group used in the 2nd example. It is a whole heat sink perspective view which shows a prior art. It is a sectional side view of the heat sink which shows a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heat-transfer board 2 Intermediate | middle board 3 Hydraulic fluid tank 4 Heat sink 4A Cooling fin 4B Fin attachment part 5 Heat generating body 6 Flat wick 7 Evaporating part 8 Upper hole 9 of an intermediate board Lower hole 10 of an intermediate board The back side of the heat-transfer board 1 Concave part 11 Concave part 20 on the back side of the intermediate plate 2 Wick set 21 Wick base 22 Wick 23 Upper hole in the wick base 24 Lower hole in the wick base 25 Clearance between the wick base and the heat transfer substrate (upper part)
26 Clearance between wick base and heat transfer board (bottom)
30 Pipe installation groove 31 Circular pipe

Claims (5)

In a heat sink in which a plurality of cooling fins for radiating heat from the heating element are erected,
The heat sink fin mounting portion is made of a highly heat conductive metal material, and is provided with a heat transfer substrate portion in which a working fluid is sealed.
The heat transfer substrate portion constitutes a loop heat pipe having a planar wick and a hydraulic fluid tank,
A heat sink characterized in that the heat transfer substrate part is covered with the fin attachment part and integrated by brazing to maintain airtightness. The heat transfer substrate part is
A heat transfer board to which the heating element is attached;
A planar wick provided on a concave surface formed on the back side of the heating element mounting surface of the heat transfer substrate;
An intermediate plate provided to cover and cover the concave portion of the heat transfer substrate;
A hydraulic fluid tank formed by covering the intermediate plate with the fin mounting portion on a concave surface formed on the surface opposite to the contact surface side with the heat transfer substrate;
With
The heat sink according to claim 1, wherein the wick portion and the hydraulic fluid tank communicate with each other through holes provided above and below the intermediate plate to form a loop heat pipe. The heat transfer substrate part is
A heat transfer board to which the heating element is attached;
A wick set installed in a concave portion on the back side of the heating element mounting surface of the heat transfer substrate;
With
The hydraulic fluid tank located between the wall surface of the wick set installed in the concave surface portion larger than the thickness of the wick set and the fin mounting portion is connected to the wick portion by holes provided above and below the wick set. The heat sink according to claim 1, wherein the heat sink is a communication loop heat pipe.   The wick set is provided with a plurality of grooves in the vertical direction on a wick base made of a metal material having a high thermal conductivity in a flat plate shape, and an elongated wick is disposed in the groove, so that the gap between the wicks of the wick base is 4. A heat sink according to claim 3, wherein the heat sink is a component of a loop type heat pipe by forming a hole in the pipe and forming a passage for working fluid and steam.   An electronic device comprising the heat sink according to any one of claims 1 to 4.

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