JP2004028508A - Cooling device, electronic appliance device, and manufacturing method for cooling device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling device, an electronic appliance device, and a manufacturing method for the cooling device, reducing a hindrance for supplying a refrigerant by a bubble to stabilize heat transport operation. <P>SOLUTION: A vaporization part 30 of the cooling device 100 comprises a plurality of protrusions 12 disposed in rows, and a liquid suction part sucking an operating fluid liquefied by using capillarity. Because the liquid suction part comprises the plurality of protrusions disposed in rows, the liquefied operating fluid can move in a row direction and in a direction between the protrusions disposed in the back-and-forth direction of the rows. Thereby, even when the bubble is generated in the liquid suction part, the liquid-phase operating fluid can bypass the bubble to flow, and a flow of the operating fluid and the heat transport operation can be stabilized. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cooling device for cooling a cooling target such as a CPU, a manufacturing method thereof, and an electronic device such as a personal computer or a digital camera equipped with the cooling device.
[0002]
[Prior art]
In order to cool a cooling target such as a CPU, a cooling device is built in the electronic device. Here, with the recent high integration and large scale of semiconductor elements, the heat value of the electronic device has been gradually increasing. Also, with the miniaturization of personal computers and the spread of personal digital assistants, miniaturization of electronic devices is required. For this reason, a cooling device built in an electronic device is required to have both improved heat transport efficiency and reduced size.
Here, a cooling device (CPL type cooling device) having a CPL (Capillary Pumped Loop) structure proposed by the National Aeronautics and Space Administration (NASA) achieves high heat transport efficiency and small size and thinness. It is expected to be possible, and development is proceeding.
The basic principle of cooling by the CPL type cooling device is almost the same as that of a normal heat pipe. That is, the enclosed refrigerant vaporizes in the evaporator, absorbs heat, and liquefies in the condenser, radiates heat. As a result, heat energy is transferred from the evaporating section to the condensing section, and the evaporating section and, consequently, the object to be cooled are cooled.
In the cooling device of the CPL system, the evaporating section has a wick configured with a micro channel array structure or the like. The wick functions as a kind of pump that sucks the refrigerant liquefied by the capillary phenomenon (suctions the refrigerant by capillary force) and supplies it to the evaporator. By supplying the refrigerant to the evaporator by the wick, the refrigerant is continuously vaporized, and the continuous operation of the cooling device is ensured.
[0003]
[Problems to be solved by the invention]
Here, bubbles may be generated in the evaporating section, making it difficult to supply the refrigerant by the wick. For example, the refrigerant vaporized in the evaporator may grow as bubbles in the liquefied refrigerant due to steady or sudden heat transfer or the like. If the generated air bubbles stay in the wick or apply pressure to the refrigerant in a direction opposite to the circulation direction, the supply of the refrigerant by the wick is obstructed, and the cooling capacity of the cooling device is reduced.
In particular, when the air bubbles generated in the evaporating section grow large and reach the entire wick, the liquid is not sucked by the capillary force, and the circulation of the refrigerant is stopped. Such a suspension of the circulation of the refrigerant causes all the refrigerant retained in the wick to evaporate, thereby causing the wick to dry out. If the wick dries out in this way, it becomes difficult to circulate the refrigerant again in the cooling device.
[0004]
In order to solve such a problem, for example, Japanese Patent Application Laid-Open No. 2001-196778 discloses an evaporating unit having a liquid holding structure in which a plurality of minute walls (microwalls) having different heights are provided and used as fins.
However, even with the above-described configuration, there is a problem that stagnation and backflow of bubbles cannot be completely eliminated, and stable operation of the cooling device cannot always be ensured.
The present invention has been made in view of the above circumstances, and provides a cooling device, an electronic device, and a method of manufacturing a cooling device that reduce the inhibition of supply of a refrigerant due to bubbles and stabilize a heat transport operation. It is aimed at.
[0005]
[Means for Solving the Problems]
A. A cooling device according to a first aspect of the present invention includes a gas flow path through which a vaporized working fluid as a vaporized working fluid passes, and a liquid phase working fluid that liquefies the gas phase working fluid that has passed through the gas flow path. And a liquid flow path through which the liquid-phase working fluid formed by the liquefaction section passes, and are arranged in a row on the plane in a direction from the liquid flow path to the gas flow path. A liquid suction / holding portion formed by a plurality of protrusions and sucking and holding the liquid-phase working fluid from the liquid flow channel by capillary action, and evaporating the liquid-phase working fluid held by the liquid suction / holding portion to vaporize And a vaporizing section for forming a phase working fluid.
The shape of the liquid suction holding unit is not a fin shape (channel array), but a plurality of protrusions arranged in rows. For this reason, the liquid-phase working fluid can move both in the direction along the row and in a different direction (the direction passing between the front and rear protrusions on the row) (flexibility of movement of the liquid-phase working fluid). Sex). As a result, even when bubbles are generated in the liquid suction holding portion, the liquid-phase working fluid can flow around the bubbles, and the flow of the liquid-phase working fluid and, consequently, the heat transport can be stabilized.
[0006]
(1) The plurality of protrusions may be arranged at intervals of 2 μm or more and 50 μm or less as viewed from a direction along the row.
The arrangement pitch of the protrusions is preferably about 2 μm or more and about 50 μm or less.
If the interval is 2 to 3 μm or less, it becomes difficult for the liquid-phase working fluid to flow efficiently, and if it is 50 μm or more, a sufficient capillary force cannot be obtained (the force for sucking the liquid-phase working fluid from the liquid flow path is weak. Become).
[0007]
(2) The conductance of the liquid-phase working fluid in the liquid suction holding section is larger in the direction from the gas flow path to the liquid flow path than in the direction from the liquid flow path to the gas flow path. As described above, the plurality of protrusions may be arranged.
By making the conductance different in the forward and reverse directions of the flow of the working fluid, the backflow of the liquid-phase working fluid from the gas flow path to the liquid flow path due to bubbles and the like generated in the liquid suction holding part is prevented, and the liquid suction holding The part can be kept from drying up.
To make the conductance different in the forward and reverse directions of the flow, for example, it is possible to make the downstream end of the projection larger than the upstream end (by increasing the width). In other words, the protrusions can be arranged so as to be asymmetrical in the forward and reverse directions, and the conductance can be made different in the forward and reverse directions.
[0008]
{Circle around (1)} Here, the shape of the plurality of projections can be columnar, or even prismatic. As this prism, an odd-numbered polygon such as a triangle and a pentagon, and an even-numbered polygon having even-numbered corners can be used.
That is, both the odd-numbered square and the even-numbered square can be used to prevent backflow. For example, even in the case of a hexagon, backflow can be prevented by making the width on the downstream side larger than the width on the upstream side.
[0009]
{Circle around (2)} The plurality of protrusions may be alternately arranged along the row and shifted in a direction different from the direction of the row. As a specific example, a case where a row of projections is zigzag or meandering can be given. Further, as an example of a case where there are a plurality of rows, a case where the protrusions are arranged in a staggered manner can be cited.
Even if the rows are misaligned, the liquid phase working fluid can be moved with flexibility, and the liquid phase working fluid can flow around the air bubbles.
In addition, backflow can be more effectively prevented. In other words, by displacing the projections in the row, the next projection is not disposed behind the projection, and the projection is exposed to the flow of the liquid-phase working fluid. For this reason, the effect of the protrusion to prevent backflow is improved.
[0010]
Here, the plurality of protrusions are arranged along a plurality of substantially parallel rows, and a distance between the plurality of protrusions and a width of the plurality of protrusions are substantially equal when viewed from a direction orthogonal to a direction along the rows. Can be equal.
As a specific example, a case can be cited in which the protrusions are arranged in a staggered manner, and the ratio of the interval between the bottom and the protrusion on the downstream side of the protrusions is about 1: 1. Backflow of the working fluid can be effectively prevented.
[0011]
(3) The vaporizing section may be composed of a first substrate on which a liquid suction holding section composed of the plurality of projections is formed, and a second substrate joined to the first substrate.
Using the substrate, the vaporizing section can be made compact.
[0012]
(4) The gas flow path and the liquid flow path can be deformable.
By making the liquid flow path deformable, flexibility in installing the cooling device is improved.
[0013]
B. An electronic apparatus according to a second aspect of the present invention includes a central processing unit, and a cooling device indicated by A disposed close to or in contact with the central processing unit.
The cooling device can effectively cool the inside of the electronic device.
[0014]
C. A method of manufacturing a cooling device according to a third aspect of the present invention includes a groove forming step of forming a groove that forms a flow path through which a working fluid passes on the first substrate, and a plurality of rows arranged in a row. A liquid suction holding portion forming step of forming a liquid suction holding portion on the second substrate, the liquid suction holding portion being formed of projections and sucking a liquid-phase working fluid using a capillary phenomenon; and a first groove formed in the groove forming step. And a joining step of joining the second substrate with the liquid suction holding section formed in the liquid suction holding section forming step.
The cooling device can be efficiently manufactured using the substrate.
Here, the liquid suction holding section forming step includes a step of forming the liquid suction holding section on a third substrate, and a step of incorporating the third substrate on which the liquid suction holding section is formed into the second substrate. May be provided.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(1st Embodiment)
FIG. 1 is an exploded perspective view showing a state where the cooling device 100 according to the first embodiment of the present invention is disassembled, and FIG. 2 is a sectional view showing a state where the cooling device 100 is cut along AB in FIG. is there.
As shown in FIGS. 1 and 2, the cooling device 100 is configured by joining two substrates 10 and 20, and has a vaporizing section 30, a gas flow path 40, a liquefying section 50, and a liquid flow path 60 therein. , A working fluid F is enclosed. The vaporization section 30, the gas flow path 40, the liquefaction section 50, and the liquid flow path 60 constitute a circulation path 70 through which the working fluid F circulates.
The working fluid F is a so-called refrigerant, and various materials such as water, ammonia, hydrocarbon, and carbon dioxide can be used.
[0016]
The vaporizing section (evaporating section) 30 is formed between the grooves 11 and 21 formed on the substrates 10 and 20, respectively, and the working fluid F changes from a liquid (liquid-phase working fluid FL) to a gas (gas-phase working fluid FG). It has a liquid suction holding portion (wick) 31, a gas inflow portion 32, and a gas-liquid separation wall 33.
[0017]
The liquid suction holding unit 31 is composed of the protrusions 12 arranged in a row on the groove 11 of the substrate 10, and sucks the liquid-phase working fluid FL from the liquid flow channel 60 using a capillary phenomenon (capillary force). ) And hold it. The liquid-phase working fluid FL held by the liquid suction holding unit 31 evaporates (evaporates), and takes heat of evaporation from the surroundings.
As described above, the liquid suction holding unit 31 performs (1) a suction function of sucking the liquid-phase working fluid FL from the liquid flow path 60 by capillary force, and (2) a holding function of temporarily holding the sucked liquid-phase fluid FL. Has functions. With this suction function, the liquid suction holding unit 31 functions as a pump for continuously circulating the working fluid F in the circulation path 70.
The details of the protrusion 12 will be described later.
[0018]
The gas inflow portion 32 is a space formed between the upper portion of the liquid suction holding portion 31 and the bottom surface of the groove 21 of the substrate 20, and the gas phase working fluid FG vaporized by the liquid suction holding portion 31 flows therein.
[0019]
The gas-liquid separation wall 33 is a projection disposed between the liquid suction holding section 31 and the gas flow path 40. The gas-liquid separation wall 33 is configured to be slightly higher in height than the protrusion 12 of the liquid suction holding section 31 and to have a width that is the full width of the groove 11.
As a result, the liquid-phase working fluid FL held by the liquid suction holding unit 31 is prevented from flowing into the gas flow path 40 while maintaining the liquid phase. On the other hand, the gas-phase working fluid FL moves to the gas flow path 40 from between the upper surface of the gas-liquid separation wall 33 and the bottom surface of the groove 21 on the lower surface of the substrate 20.
[0020]
The gas flow path 40 is configured by the groove 13 formed in the substrate 10 and the lower surface of the substrate 20, and is a path through which the vapor-phase working fluid FG vaporized in the vaporization unit 30 moves to the liquefaction unit 50.
[0021]
The liquefaction unit (condensing unit) 50 is configured between the groove 14 formed on the substrate 10 and the lower surface of the substrate 20, and is a portion where the working fluid F changes phase from gas to liquid, and includes a plurality of condensing fins. 51 are arranged in parallel. The gas-phase working fluid FG that has flowed in from the gas flow path 40 is liquefied by the condensing fins 51 to form a liquid-phase working fluid FL, and releases heat during the liquefaction.
[0022]
The liquid flow path 60 is composed of the groove 15 formed in the substrate 10 and the lower surface of the substrate 20, and is a path through which the working fluid F liquefied by the liquefaction unit 50 moves to the vaporization unit 30.
[0023]
The grooves 16 and 26 formed in the substrates 10 and 20, respectively, constitute a heat insulating space 80 integrally. The heat insulating space 80 restricts the conduction of heat through the substrates 10 and 20 between the vaporizer 30, the gas flow path 40, the liquefier 50, and the liquid flow path 60, thereby improving the cooling efficiency of the cooling device 100. I have.
[0024]
(Details of the liquid suction holding unit 31)
As described above, the liquid suction holding unit 31 includes the protrusions 12 arranged in a row on the groove 11 of the substrate 10. Hereinafter, details of the protrusion 12 will be described.
FIG. 3 is a top view illustrating the arrangement of the protrusions 12 of the liquid suction holding unit 31.
As shown in FIG. 3, the protrusions 12 are arranged in an array in a row in both the positive Y direction (liquid inflow direction) from the liquid flow channel 60 to the gas flow channel 40 and the X direction orthogonal to this. .
[0025]
(1) Capillary force acts in the space between the projections 12 to suck the liquid-phase working fluid FL from the liquid flow channel 60, so that the liquid surface faces the gas inlet 32. In order to cause the liquid-phase working fluid FL to be sucked by the capillary force, the space distance between the projections 12 needs to be reduced to some extent (the projections 12 are distributed densely to some extent). As shown in FIG. 3, the distance between the projections 12 includes a distance dx in the X direction and a distance dy in the Y direction. For example, by setting both of them to within 50 μm, the capillary force of the liquid-phase working fluid FL Suction can be performed.
On the other hand, if the distribution of the projections 12 becomes too dense, the resistance when the liquid-phase working fluid FL moves from the liquid flow path 60 to the gas flow path 40 increases, so that the distance between the projections 12 becomes two. It is preferable that the thickness be about 3 μm or more.
[0026]
(2) Since the projections 12 are arranged in an array, the liquid-phase working fluid FL can move not only in the positive Y direction from the liquid flow path 60 to the gas flow path 40 but also in the X direction perpendicular to the Y direction. It becomes. This has the effect of reducing the inhibition of the movement of the liquid-phase working fluid FL in the liquid suction holding unit 31 by bubbles as described below.
[0027]
In the liquid suction holding unit 31, when the liquid-phase working fluid FL evaporates, the volume may expand rapidly and bubbles may be generated in the liquid-phase working fluid FL (for example, so-called bumping). These bubbles may stay in the liquid suction holding section 31 and hinder the movement of the liquid phase working fluid FL in the liquid suction holding section 31.
Since the projections 12 are arranged in an array, even when a portion between the projections 12 is closed, the liquid-phase working fluid FL can move around the projections.
FIG. 4 is a top view illustrating a state in which the liquid-phase working fluid FL bypasses the air bubbles 91 in the suction holding section 31. It can be seen that even if there are bubbles 91 between the projections 12 arranged in an array, the liquid-phase working fluid FL can move around this.
As described above, by arranging the protrusions 12 in an array, flexibility of movement of the liquid-phase working fluid FL is secured (movement in at least a plurality of directions is possible), and bubbles and the like in the liquid suction holding unit 31 are reduced. This can prevent the movement of the liquid-phase working fluid FL from being hindered.
[0028]
(3) As shown in FIGS. 2 and 3, the projection 12 is columnar, and its cross section is a triangle (here, an isosceles triangle). The apex p1 of the triangle is arranged so as to be in the inflow direction (Y negative direction) of the liquid phase working fluid FL, and the base b of the isosceles triangle is in the outflow direction (Y positive direction) of the liquid phase working fluid FL. . This contributes to the backflow prevention of the liquid phase working fluid FL.
The arrangement of the protrusions 12 causes asymmetry in the inflow / outflow direction of the liquid-phase working fluid FL, resulting in a difference in conductance between the positive and negative directions of the flow. Further, the protrusion 12 is arranged so that the width of the flow of the liquid-phase working fluid FL in the reverse direction is larger than that in the forward direction. As a result, the liquid-phase working fluid FL flows more easily in the positive direction (Y positive direction) of the flow from the inflow direction to the outflow direction than in the reverse flow direction (Y negative direction).
[0029]
FIGS. 5A and 5B are diagrams schematically showing a state where the liquid-phase working fluid FL flows in the liquid suction holding unit 31. FIG. Here, FIG. 5A shows the liquid-phase working fluid FL in the forward direction (the direction from the liquid flow channel 60 side to the gas flow channel 40 side), and FIG. This indicates a state in which the gas flows in a direction from the gas flow path 40 to the liquid flow path 60).
As shown in FIG. 5A, in the forward flow, the resistance of the projection 12 to the liquid-phase working fluid FL is small, and the liquid-phase working fluid FL flows smoothly. On the other hand, as shown in FIG. 5B, even when the liquid-phase working fluid FL is going to flow backward, the protrusion 12 has a shape with high resistance to the backflow, so that the backflow of the refrigerant can be reduced. .
As described above, due to the arrangement of the protrusions 12, the liquid suction holding unit 31 has a function of ensuring the unidirectionality of the flow direction of the working liquid F (backflow prevention).
[0030]
The bubbles generated in the liquid suction holding section 31 not only hinder the movement of the liquid phase working fluid FL, but also cause the liquid phase working fluid FL to flow backward, which may cause the liquid suction holding section 31 to dry up.
The arrangement of the projections 12 prevents the liquid-phase working fluid FL from flowing backward, thereby preventing the liquid suction holding section 31 from drying up and allowing the liquid-phase working fluid FL to stably circulate.
[0031]
(4) FIG. 6 shows another example of the arrangement of the protrusions 12 on the liquid suction holding unit 31. Here, the projections 12 are arranged in a staggered manner. That is, the projections 12 of the next (n + 1) th row are arranged between the projections 12 of the nth row arranged in the X direction of the projections 12. Thus, when the projections 12 of the next row are arranged between the projections 12 of one row, the projections 12 of different rows are hidden behind the other projections 12 when viewed from the direction of flow of the liquid-phase working fluid FL. Will be arranged without any change.
By arranging the protrusions 12 in a staggered manner in this manner, it is possible to more effectively prevent the backflow of the liquid-phase working fluid FL.
[0032]
FIGS. 7A and 7B are views schematically showing a state where the liquid-phase working fluid FL flows in the liquid suction holding section 31 shown in FIG. Here, FIG. 7A shows the liquid-phase working fluid FL in the forward direction (the direction from the liquid flow channel 60 side to the gas flow channel 40 side), and FIG. 7B shows the liquid-phase working fluid FL in the reverse direction. This indicates a state in which the gas flows in a direction from the gas flow path 40 to the liquid flow path 60).
As can be seen by comparing FIGS. 7A and 7B with FIGS. 5A and 5B, by arranging the protrusions 12 in a staggered manner, the backflow prevention effect can be further improved.
[0033]
(5) It is also possible to use a shape other than the triangular prism shape as the shape of the protrusion 12 of the liquid suction holding unit 31.
8 to 10 are top views illustrating examples of the arrangement of the protrusions 12 in the liquid suction holding unit 31.
FIG. 8 shows an example in which a pentagonal projection 12a is used as the projection. The pentagonal projections 12a are arranged so that the width is larger on the reverse side than on the forward side of the flow, like the triangular projections. As a result, the backflow of the working liquid F is efficiently prevented, and the working liquid F flows stably.
[0034]
FIG. 9 shows a state in which the columnar projections 12c are mixed and arranged in the triangular columnar projections 12b. FIG. 10 shows an example in which a triangular prism-shaped projection 12e is arranged between the channel array-shaped projections 12d.
Thus, it is not necessary that all the projections 12 have the same shape. Also, a part of the protrusion 12 may include a channel array-shaped protrusion.
[0035]
(6) Summarizing the above, by arranging the protrusions 12 in a row, the flow of the working liquid F is provided with flexibility, and the flow of the working liquid F in the liquid suction holding unit 31 is caused by the generated bubbles. Inhibition can be reduced.
In addition, by arranging the protrusions 12 so as to be asymmetrical in the forward and reverse directions of the flow, the backflow of the working liquid F in the liquid suction holding unit 31 can be prevented. Further, the staggered arrangement of the projections 12 can more effectively prevent backflow.
The supply of the working liquid F to the liquid suction / holding unit 31 is ensured by preventing the flow of the working liquid F due to the bubbles (including the backflow) in the liquid suction / holding unit 31 as described above.
Since the supply of the working liquid F is ensured, even if the liquid-phase working fluid FL held by the liquid suction holding unit 31 is continuously vaporized, its drying (dryout) can be prevented.
[0036]
(Operation of cooling device 100)
The operation of the cooling device 100 will be described.
In the cooling device 100, the working fluid F circulates through the vaporizing section 30, the gas flow path 40, the liquefying section 50, and the liquid flow path 60 as the circulation path 70, so that the heat of the vaporizing section 30 moves to the liquefying section 50. The details will be described below.
[0037]
The liquid-phase working fluid FL flows from the liquid flow path 60 into the vaporizing section 30. This inflow is performed by capillary action in the liquid suction holding section 31 of the vaporizing section 30 (suction by capillary force).
The liquid-phase working fluid FL sucked by the liquid suction holding unit 31 absorbs heat and is vaporized while being held by the liquid suction holding unit 31. The vaporized working fluid F (gas-phase working fluid FG) flows into the gas inflow portion 32, passes over the gas-liquid separation wall 33, and flows into the gas flow path 40.
The gas-phase working fluid FG that has flowed into the gas flow path 40 flows into the liquefaction unit 50, is liquefied by the condensing fins 51, and radiates heat.
As described above, the working fluid F circulates through the circulation path 70, and the heat absorption by the vaporization in the vaporization unit 30 and the heat release by the liquefaction in the liquefaction unit 50 are continuously performed. As a result, the heat of the vaporization unit 30 is transferred to the liquefaction unit 50, and the cooling target that is in contact with or in proximity to the vaporization unit 30 is cooled.
[0038]
During the operation of the cooling device 100, the movement of the gas-phase working fluid FG in the liquid suction holding unit 31 can be prevented from being hindered by bubbles due to the protrusions 12 arranged in a line on the liquid suction holding unit 31. . Further, by ensuring unidirectional flow, the working fluid F is circulated in the circulation path 70 more reliably.
As a result, it is possible to prevent the cooling efficiency of the cooling device 100 from being reduced due to the bubbles, and to prevent the operation of the cooling device 100 from being stopped due to dryout.
[0039]
(2nd Embodiment)
FIG. 11 is an exploded perspective view showing an exploded state of the cooling device 200 according to the second embodiment of the present invention. FIGS. 12A and 12B show the assembled cooling device 200 in FIG. It is sectional drawing showing the cross section cut | disconnected by -D and EF.
As shown in FIGS. 11 and 12, the cooling device 200 includes four substrates 210 to 240. The substrates 230 and 240 are incorporated into the holes 221 and 222 of the substrate 220 without gaps, respectively. Further, the substrates 210 and 220 are bonded and fixed.
13 to 15 are top views illustrating the substrates 210 and 220 constituting the cooling device 200 and a state in which both are combined. Here, the substrate 220 is shown in a state where it is combined with the substrates 230 and 240.
[0040]
As shown in FIGS. 11 to 15, the cooling device 200 is configured by combining four substrates 210 to 240, and has a vaporizer 250, a gas flow channel 260, a liquefier 270, and a liquid flow channel 280 therein. A working fluid (refrigerant) F is sealed. The vaporizing section 250, the gas flow path 260, the liquefying section 270, and the liquid flow path 280 constitute a circulation path 290 through which the working fluid F circulates, as in the first embodiment.
[0041]
The substrates 210 and 220 are preferably made of a material having relatively high thermal insulation, and the substrates 230 and 240 are preferably made of a material having relatively high thermal conductivity.
The liquid suction holding portion 251 formed on the substrate 230 and the condensing fin 271 formed on the substrate 240 have a function of absorbing and radiating heat, and therefore preferably have good thermal conductivity. On the other hand, it is preferable that components other than the liquid suction holding unit 251 and the condensing fin 271 constituting the cooling device 200 have a certain degree of thermal insulation in order to limit unnecessary heat conduction.
Specifically, the substrates 210 and 220 can be made of, for example, plastic, glass, or a combination of both, and the substrates 230, 240 can be made of, for example, a metal such as nickel or copper.
However, if the thickness of the liquid suction holding section 251 and the condensing fin 271 is reduced, heat exchange with the outside will not be hindered even if the thermal conductivity of the constituent material itself is not so good.
[0042]
The vaporizer 250 is formed between the groove 211 on the substrate 210 and the substrate 230, and is a portion where the working fluid F changes its phase from a liquid (liquid-phase working fluid FL) to a gas (gas-phase working fluid FG). , A liquid suction holding section (wick) 251 and a gas inflow section 252.
[0043]
The liquid suction holding section 251 is composed of protrusions 232 arranged in rows on grooves 231 formed on the lower surface of the substrate 230. The structure and function of the projection 231 are not basically different from those of the first embodiment, so that the description is omitted.
[0044]
The gas inflow portion 252 is a space formed between the lower portion of the liquid suction holding portion 251 and the bottom surface of the groove 211 of the substrate 210, into which the working fluid F vaporized by the liquid suction holding portion 251 flows.
[0045]
The gas flow path 260 is configured by the groove 212 formed in the substrate 210 and the lower surface of the substrate 220, and is a path for moving the working fluid vaporized in the vaporization unit 250 to the liquefaction unit 270.
[0046]
The liquefaction unit (condensing unit: condenser) 270 is configured between the groove 213 of the substrate 210 and the lower surface of the substrate 240, and is a portion where the working fluid F changes its phase from gas to liquid, and is arranged in parallel. It has a plurality of condensation fins 271. The condensing fins 271 are formed by forming grooves 241 in parallel on the substrate 240. That is, the constituent material of the substrate 240 between the grooves 241 becomes the condensation fin 271.
[0047]
The liquid flow path 280 is configured by the groove 214 formed in the substrate 210 and the lower surface of the substrate 220, and is a path for moving the working fluid liquefied by the liquefaction unit 270 to the vaporization unit 250.
[0048]
The grooves 216 and 226 formed in the substrates 210 and 220 respectively form a heat insulating space 291 integrally. The heat insulating space 291 restricts the conduction of heat through the substrates 210 and 220 between the vaporizing section 250, the gas flow path 260, the liquefying section 270, and the liquid flow path 280, and reduces the cooling efficiency of the cooling device 200. It is preventing.
[0049]
Further, the cooling device 200 has a reservoir 292 and a storage unit 293 for storing the liquid-phase working fluid FL.
The reservoir 292 includes a groove 217 formed in the substrate 210 and a lower surface of the substrate 220. When the amount of the liquid-phase working fluid FL held by the liquid suction holding unit 251 becomes equal to or less than a predetermined amount, the stored liquid-phase working fluid FL flows into the liquid suction holding unit 251. This inflow is performed by suction of the liquid-phase working fluid FL from the grooves 217 a and 217 b connected to the reservoir 292 to the liquid suction holding portion 251 by capillary force.
[0050]
The storage unit 293 includes a groove 218 formed in the substrate 210 and a lower surface of the substrate 220. When the liquid-phase working fluid FL held in the liquefaction unit 270 becomes equal to or less than a predetermined amount, the stored liquid-phase working fluid FL flows into the liquefaction unit 270. This inflow is caused by the fact that the liquid-phase working fluid FL moves from the storage unit 293 to the liquefaction unit 270 through the condensation fin 271 because a part of the condensation fin 271 (groove 241) faces the storage unit 293. Done in
[0051]
As described above, the reservoir 292 and the storage unit 293 store the liquid-phase working fluid FL for preventing the inside of the circulation path 290 from drying (drying out), and store the liquid-phase working fluid FL as necessary. It is allowed to flow into the circulation path 290.
[0052]
The cooling device 200 is different from the first embodiment in that the liquid suction holding unit 251 and the condensing fin 271 are different from the substrate 210 in which the grooves 212 and 214 forming the gas flow path 260 and the liquid flow path 280 are formed. 230 and 240 are formed.
However, the operation is essentially the same as in the first embodiment. The liquid suction holding unit 251 sucks the liquid-phase working fluid FL from the liquid flow path 280 and vaporizes it into the gas inflow unit 252, whereby the cooling operation proceeds.
At this time, similarly to the first embodiment, the protrusion 232 prevents the suction and the backflow of the working fluid F caused by the bubbles.
[0053]
(Method of manufacturing cooling device 200)
FIG. 16 shows an example of a manufacturing process of the cooling device 200.
(1) First, grooves are formed in the substrate (lower substrate) 210 and the substrate (upper substrate) 220 (step 1).
On the upper surface of the substrate 210, channels 260 and 280, storage tanks (reservoirs 292 and storage sections 293) for storing liquid, grooves 211 to 218 functioning as heat insulating spaces 291 and the like are formed. On the other hand, a groove 216 functioning as a heat insulating space 291 is formed on the lower surface of the substrate 220.
In order to form a groove on each of the substrates 210 and 220, for example, when a plastic material is used for the substrates 210 and 220, a mold is prepared for each of the substrates 210 and 220 in advance, and the plastic material is formed using the mold. Can be considered.
The substrates 210 and 220 may be made of glass. In this case, after forming a resist pattern on the substrates 210 and 220, a groove can be formed by etching.
[0054]
(2) Next, the substrates 230 and 240 functioning as the condensation fin (condenser) 271 or the liquid suction holding unit (wick) 251 are formed (Step 2).
The substrates 230 and 240 having the grooves can be manufactured by various methods. In particular, there are many types of wick manufacturing methods based on the present invention, and various types can be used depending on the situation.
Among them, a MEMS (Micro Electro Mechanical System) technology, which has recently attracted attention as a microfabrication technology, can be suitably used. More specifically, the protrusion 232 is formed by a technology of deeply digging a material such as silicon with a high aspect ratio of several tens μm or more based on a UV-LIGA (Lithographie Galvanoform AbFormung) process or a Deep RIE (Reactive Ion Etching) technology. It can be suitably formed.
[0055]
Here, the UV-LIGA process will be specifically described with reference to FIG.
First, as shown in FIG. 17A, a resist layer 382 made of, for example, SU-8 which is an organic material is formed on a plate 381, and a patterned resist film 383 is formed thereon. This is called a pattern substrate 380.
Next, as shown in FIG. 17B, UV is irradiated from above the pattern substrate 380 to etch the resist layer 382.
Next, as shown in FIG. 17C, the resist film 383 is peeled from the pattern substrate 380, and a nickel layer 384 is formed on the surface by electroforming nickel nickel. Then, as shown in FIG. 17D, the nickel layer 384 is separated from the pattern substrate 380. The peeled nickel layer 384 becomes the substrates 230 and 240 having protrusions or grooves.
[0056]
(3) The substrates 230 and 240 formed as described above are incorporated into the holes 221 and 22 formed through the substrate 220 as shown in FIG. 18 (Step 3). At this time, if the constituent material of the substrate 220 is plastic, heat is applied to the substrate 220 to keep it in a semi-solid state, and the substrates 230 and 240 are inserted into the holes 221 and 222. This is to prevent a gap from being formed between the substrate 220 and each of the substrates 230 and 240.
(4) Next, as shown in FIG. 19A, a copper thin film 210a as an adhesive member is formed on the upper surface of the substrate 210 by, for example, sputtering.
After that, as shown in FIG. 19B, the substrates 210 and 220 are bonded by, for example, ultrasonic bonding or heat fusion bonding (step 4).
[0057]
According to the above-described manufacturing method, the cooling device can be efficiently manufactured. The cooling device 100 can be manufactured in a manner similar to the cooling device 200.
In the above-described manufacturing method, the liquid suction holding portion (wick) 251 and the condensing fin 271 are formed using a metal material (nickel), but they can be formed using more various materials.
For example, columnar projections can be formed by anisotropically etching a crystalline material such as silicon by a wet process. Also, by using a dry etching technique such as Deep RIE, silicon or SiO ₂ , SiNx, glass materials and the like can be used.
Since the liquid suction holding portion 251 and the condensing fin 271 have a function of absorbing and radiating heat, it is preferable to use a thermally conductive material. However, if these thicknesses are reduced, the thermal conductivity of the material itself is reduced. Even if it is not so good, it will not hinder heat exchange with the outside.
[0058]
(Third embodiment)
FIG. 20 shows, as a third embodiment of the present invention, a flexible cooling device 400 configured by connecting a liquefaction unit 410 and a vaporization unit 420 with a flexible substrate 430.
The liquefaction unit 410 and the vaporization unit 420 are made of plastic, respectively, and incorporate a liquid suction holding unit composed of metal substrates 411 and 421 and a condensation fin.
The flexible substrate 430 is made of plastic and includes a heat pipe flow path 431 therein. These base materials or substrates are integrated to form a heat pipe.
The flexible substrate 430 can be freely deformed. For example, the vaporizing section 420 can be attached to the heat generating section of the electronic device, and the flexible substrate can be closely attached so as to conform to the shape of the external surface of the electronic device.
[0059]
(Application to electronic equipment)
The cooling devices 100 and 200 can be mounted on electronic devices such as personal computers, digital cameras, and video cameras.
In the cooling devices 100 and 200, the liquid suction holding unit (wick) of the vaporizing unit (evaporating unit) is formed of a row of projections, so that the liquid suction holding unit sucks the gas-phase working fluid, and further, performs the heat transport operation. Is stabilized. For this reason, the cooling devices 100 and 200 are suitable for cooling semiconductor elements, which are becoming more highly integrated and larger in scale, and electronic devices using them. In particular, it is suitable for cooling CPUs of personal computers, personal digital assistants, and the like, which are becoming smaller.
For example, the cooling device can be used for cooling a central processing unit (CPU) of a personal computer. Further, in order to cool a detachable recording medium having a flash memory and a driver, a liquid suction holding unit may be arranged immediately below a driver of a recording medium mounted in a slot for attaching and detaching the recording medium.
[0060]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a cooling device, an electronic device, and a method of manufacturing a cooling device that reduce the inhibition of supply of a refrigerant due to bubbles and stabilize a heat transport operation. it can.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a state where a cooling device according to a first embodiment of the present invention is disassembled.
FIG. 2 is a sectional view illustrating a state in which the cooling device according to the first embodiment of the present invention is cut off.
FIG. 3 is a top view illustrating an example of an arrangement of protrusions on a liquid suction holding unit.
FIG. 4 is a top view illustrating a state in which a liquid-phase working fluid bypasses bubbles in a suction holding unit.
FIG. 5 is a diagram schematically showing a state when a liquid-phase working fluid flows through a liquid suction holding unit.
FIG. 6 is a top view illustrating another example of the arrangement of the protrusions on the liquid suction holding unit.
FIG. 7 is a diagram schematically illustrating a state in which a liquid-phase working fluid flows through a liquid suction holding unit.
FIG. 8 is a top view showing an example of the arrangement of protrusions in the liquid suction holding unit.
FIG. 9 is a top view showing an example of the arrangement of protrusions in the liquid suction holding unit.
FIG. 10 is a top view showing an example of the arrangement of protrusions in the liquid suction holding unit.
FIG. 11 is an exploded perspective view showing a state where a cooling device according to a second embodiment of the present invention is disassembled.
FIG. 12 is a cross-sectional view illustrating a state where a cooling device according to a second embodiment of the present invention is cut off.
FIG. 13 is a top view illustrating a substrate included in a cooling device according to a second embodiment of the present invention.
FIG. 14 is a top view illustrating a substrate included in a cooling device according to a second embodiment of the present invention.
FIG. 15 is a top view illustrating a substrate included in a cooling device according to a second embodiment of the present invention.
FIG. 16 is a flowchart illustrating an example of a manufacturing process for manufacturing the cooling device according to the present invention.
FIG. 17 is a side view illustrating a state during a manufacturing process of manufacturing the cooling device according to the present invention.
FIG. 18 is a side view illustrating a state during a manufacturing process of manufacturing the cooling device according to the present invention.
FIG. 19 is a side view illustrating a state during a manufacturing process of manufacturing the cooling device according to the present invention.
FIG. 20 is a perspective view illustrating a cooling device according to a third embodiment of the present invention.
[Explanation of symbols]
100 cooling device
10,20 substrate
11, 13 to 15, 21, 26 grooves
12 protrusions
30 Vaporization unit
31 Liquid suction holder
32 gas inlet
33 Gas-liquid separation wall
40 gas flow path
50 Liquefaction unit
51 Condensing fin
60 liquid flow path
70 Circulation path
80 Insulated space

Claims (12)

A gas flow path through which a vapor-phase working fluid, which is a vaporized working fluid, passes;
A liquefier that liquefies the gas-phase working fluid that has passed through the gas flow path to form a liquid-phase working fluid,
A liquid flow path through which a liquid-phase working fluid formed in the liquefaction unit passes;
A liquid suction device comprising a plurality of protrusions arranged in a row in a direction from the liquid flow path to the gas flow path on a plane, and sucking and holding a liquid-phase working fluid from the liquid flow path by capillary action. A vaporizer that has a holding unit and vaporizes a liquid-phase working fluid held by the liquid suction holding unit to form a gas-phase working fluid.
A cooling device comprising: The cooling device according to claim 1, wherein the plurality of protrusions are arranged at intervals of 2 μm or more and 50 μm or less as viewed from a direction along the row. The conductance of the liquid-phase working fluid in the liquid suction holding section is larger in the direction from the gas flow path to the liquid flow path than in the direction from the liquid flow path to the gas flow path, The cooling device according to claim 1, wherein the plurality of protrusions are arranged. The cooling device according to claim 3, wherein the plurality of projections have a columnar shape. The cooling device according to claim 4, wherein the plurality of protrusions have a prismatic shape. 4. The cooling device according to claim 3, wherein the plurality of protrusions are alternately arranged along the row and shifted in a direction different from a direction along the row. The plurality of protrusions are arranged along a plurality of substantially parallel rows, and a distance between the plurality of protrusions and a width of the plurality of protrusions are substantially equal when viewed from a direction orthogonal to a direction along the row. The cooling device according to claim 6, characterized in that: The vaporization unit includes a first substrate on which a liquid suction holding unit composed of the plurality of protrusions is formed, and a second substrate bonded to the first substrate. The cooling device according to claim 1. The cooling device according to claim 1, wherein the gas flow path and the liquid flow path are deformable. A central processing unit,
And a cooling device arranged in proximity to or in contact with the central processing unit,
The cooling device,
A gas flow path through which a vapor-phase working fluid, which is a vaporized working fluid, passes;
A liquefier that liquefies the gas-phase working fluid that has passed through the gas flow path to form a liquid-phase working fluid,
A liquid flow path through which a liquid-phase working fluid formed in the liquefaction unit passes;
A liquid suction device comprising a plurality of protrusions arranged in a row in a direction from the liquid flow path to the gas flow path on a plane, and sucking and holding a liquid-phase working fluid from the liquid flow path by capillary action. A vaporizer that has a holding unit and vaporizes a liquid-phase working fluid held by the liquid suction holding unit to form a gas-phase working fluid.
An electronic apparatus comprising: A groove forming step of forming a groove constituting a flow path through which the working fluid passes on the first substrate;
A liquid suction holding portion forming step of forming a liquid suction holding portion on the second substrate, the liquid suction holding portion comprising a plurality of projections arranged in a row, and sucking and holding the liquid-phase working fluid by using a capillary phenomenon;
A bonding step of bonding the first substrate having the groove formed in the groove forming step and the second substrate having the liquid suction holding section formed in the liquid suction holding section forming step;
A method for manufacturing a cooling device, comprising: The liquid suction holding portion forming step,
Forming the liquid suction holding section on a third substrate;
The method of manufacturing a cooling device according to claim 11, further comprising: incorporating a third substrate on which the liquid suction holding section is formed, into the second substrate.

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