JP2018076978A - Loop heat pipe and electronic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the heat transport performance of a loop heat pipe. SOLUTION: A laminated body 44 in which a first metal sheet 41, a second metal sheet 42, and a third metal sheet 43 are laminated in order, and a first metal sheet 41 and a second metal sheet 42 are provided. A first loop-shaped first flow path 25 provided between them and filled with the first working fluid C1 and a first flow path 25 provided in the middle of the first flow path 25 to evaporate the first working fluid C1. A loop-shaped second flow path 26 provided between the evaporator 31 and the second metal sheet 42 and the third metal sheet 43 and in which the second working fluid C2 is sealed, and the second flow. A second evaporator 35 provided in the middle of the path 26 to evaporate the second working fluid C2 and a part of the laminated body 44 are provided to condense the first working fluid C1 and the second working fluid C2. By a loop heat pipe having a condenser 27 to be made to. [Selection diagram] FIG. 7

Description

  The present invention relates to a loop heat pipe and an electronic device.

  With the spread of small and thin electronic devices such as smartphones and tablet terminals, various methods for cooling heat-generating components such as a CPU (Central Processing Unit) incorporated in these electronic devices have been proposed.

  As a method for cooling the heat generating component, for example, there is a method of transporting the heat of the heat generating component to the outside with a metal plate or a heat diffusion sheet having good thermal conductivity. However, in this method, the heat that can be transported is limited by the thermal conductivity of the metal plate or the thermal diffusion sheet. For example, the thermal conductivity of a graphite sheet used as a thermal diffusion sheet is about 500 W / mK to 1500 W / mK. With this thermal conductivity, the heat generating component is cooled when the heat generation amount of the heat generating component increases. It becomes difficult.

  Therefore, a heat pipe has been studied as a device that actively moves the heat of the heat generating component and cools the heat generating component.

  The heat pipe is a device that transports heat by utilizing the phase change of the working fluid, and can perform heat transport more efficiently than the above heat diffusion sheet. For example, a heat pipe having a diameter of 3 mm exhibits a large thermal conductivity corresponding to about 1500 W / mK to 2500 W / mK.

  There are several types of heat pipes. The loop heat pipe includes an evaporator that vaporizes the working fluid by the heat of the heat-generating component, and a condenser that cools and vaporizes the vaporized working fluid. The evaporator and the condenser are connected in a loop by a pipe such as a steam pipe or a liquid pipe, and a working fluid is sealed inside the evaporator and the condenser.

  The loop heat pipe has a single direction of flow of the working fluid, so the working fluid in the liquid phase and its vapor receive less resistance than the heat pipe that reciprocates in the pipe, and efficiently transports heat. be able to.

International Publication No. 2015/087451

  However, when a loop heat pipe is mounted on a thin electronic device, the above-described evaporator, condenser, liquid pipe, and evaporator must be flattened in accordance with the thickness of the electronic device. As a result, depending on the layout of the liquid pipe and the steam pipe, it becomes difficult for the working fluid to flow through these pipes, and the heat transport performance of the loop heat pipe may be deteriorated.

  The disclosed technology has been made in view of the above, and aims to improve the heat transport performance of a loop heat pipe.

  According to one aspect, a laminate in which a first metal sheet, a second metal sheet, and a third metal sheet are sequentially laminated, and between the first metal sheet and the second metal sheet. A loop-shaped first flow path in which a first working fluid is enclosed, and a first evaporator provided in the middle of the first flow path for evaporating the first working fluid; A loop-like second flow path provided between the second metal sheet and the third metal sheet and enclosing a second working fluid, and provided in the middle of the second flow path. A second evaporator for evaporating the second working fluid; provided in a part of the stacked body; and overlapping each of the first flow path and the second flow path in plan view; A loop heat pipe is provided having a condenser for condensing the first working fluid and the second working fluid.

  According to one aspect, in the present invention, a first flow path is provided between the first metal sheet and the second metal sheet, and between the second metal sheet and the third metal sheet. Is provided with a second flow path. As described above, since the first flow path and the second flow path are provided between different layers of each metal sheet, a step does not occur at the intersection even when these flow paths intersect in plan view. As a result, the flow of the first working fluid and the second working fluid can be prevented from stagnation due to the step, and as a result, the heat transport performance of the loop heat pipe can be improved.

FIG. 1 is a schematic diagram of a loop heat pipe used for the study. FIG. 2 is an exploded perspective view of the loop heat pipe used for the study. FIG. 3 is a cross-sectional view taken along the line II of FIG. FIG. 4 is a plan view of an electronic apparatus including two heat generating components. FIG. 5 is a perspective view of a loop heat pipe provided in an overlapping manner. FIG. 6 is a cross-sectional view for explaining another problem that occurs at an intersection. FIG. 7 is a plan view of the electronic apparatus according to the first embodiment. FIG. 8 is a perspective view of the loop heat pipe according to the first embodiment. FIG. 9 is an exploded perspective view of the loop heat pipe according to the first embodiment at the intersection. FIG. 10A is a cross-sectional view taken along the line II-II in FIG. 7, and FIG. 10B is a cross-sectional view for explaining another structure of the second metal sheet according to the first embodiment. . FIG. 11 is a plan view (part 1) in the middle of processing the first metal sheet according to the first embodiment. FIG. 12 is a plan view (No. 2) in the middle of processing the first metal sheet according to the first embodiment. FIG. 13: is sectional drawing (the 1) in the middle of the process of the 1st metal sheet which concerns on 1st Embodiment. FIG. 14 is a cross-sectional view (part 2) in the middle of processing the first metal sheet according to the first embodiment. FIG. 15 is a plan view of a third metal sheet according to the first embodiment. FIG. 16 is a cross-sectional view of a third metal sheet according to the first embodiment. FIG. 17: is a top view (the 1) in the middle of the process of the 2nd metal sheet which concerns on 1st Embodiment. FIG. 18 is a plan view (part 2) in the middle of processing the second metal sheet according to the first embodiment. FIG. 19 is a plan view (part 3) in the middle of processing the second metal sheet according to the first embodiment. FIG. 20 is a cross-sectional view (part 1) in the middle of processing the second metal sheet according to the first embodiment. FIG. 21 is a cross-sectional view (part 2) in the middle of processing the second metal sheet according to the first embodiment. FIG. 22 is a cross-sectional view (No. 3) in the middle of processing the second metal sheet according to the first embodiment. FIG. 23 is a plan view of the loop heat pipe according to the first embodiment during production (part 1). FIG. 24 is a plan view (part 1) of the loop heat pipe according to the first embodiment during manufacture. FIG. 25 is a cross-sectional view of a laminate in which the first to third metal sheets according to the first embodiment are laminated. FIG. 26 is a plan view of a loop heat pipe according to the second embodiment. FIG. 27: is a top view (the 1) in the middle of manufacture of the loop heat pipe which concerns on 2nd Embodiment. FIG. 28 is a plan view (part 2) of the loop heat pipe according to the second embodiment during manufacture. FIG. 29 is a plan view (part 3) of the loop heat pipe according to the second embodiment during manufacture. FIG. 30 is a cross-sectional view of a laminate in which the first to fourth metal sheets according to the second embodiment are laminated.

  Prior to the description of the present embodiment, considerations made by the present inventor will be described.

  FIG. 1 is a schematic diagram of a loop heat pipe used for the study.

  The loop heat pipe 1 is accommodated in a thin electronic device 2 such as a smartphone, and includes an evaporator 3 and a condenser 4.

  A vapor pipe 5 and a liquid pipe 6 are connected to the evaporator 3 and the condenser 4, and a loop-like flow path through which the working fluid C flows is formed by these pipes 5 and 6. In addition, a heat generating component 7 such as a CPU is fixed to the evaporator 3, and a vapor Cv of the working fluid C is generated by the heat of the heat generating component 7.

  The steam Cv is guided to the condenser 4 through the steam pipe 5. The condenser 4 has a function of cooling and liquefying the steam Cv by heat exchange with the outside air, and has a plate shape in order to increase the contact area with the outside air. Then, the working fluid C liquefied by the condenser 4 is supplied again to the evaporator 3 through the liquid pipe 6.

  Thus, when the working fluid C flows through the loop-shaped flow path, the heat generated in the heat generating component 7 moves to the condenser 4 and the heat generating component 7 is cooled.

  FIG. 2 is an exploded perspective view of the loop heat pipe 1.

  As shown in FIG. 2, the loop heat pipe 1 includes a first copper sheet 11 and a second copper sheet 12, and is manufactured by joining them.

  FIG. 3 is a cross-sectional view taken along the line II of FIG.

  As shown in FIG. 3, the 1st copper sheet 11 and the 2nd 2nd copper sheet 12 are provided with the 1st groove | channel 11a and the 2nd groove | channel 12a, respectively. And by joining these copper sheets 11 and 12, the vapor | steam pipe | tube 5 and the liquid pipe 6 of flat cross-sectional shape are demarcated by each groove | channel 11a, 12a.

  According to such a loop heat pipe 1, since it is produced by joining the first copper sheet 11 and the second copper sheet 12, a thin heat pipe 1 suitable for a thin electronic device 2 such as a smartphone. Can be obtained.

  However, since the evaporator 3 provided in the loop heat pipe 1 is only one, in the electronic device 2 provided with the plurality of heat generating components 7, a plurality of loop heat pipes 1 are provided for each of the plurality of heat generating components 7. Must be prepared.

  FIG. 4 is a plan view of the electronic apparatus 2 including the two heat generating components 7.

  In FIG. 4, the same elements as those described in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and the description thereof is omitted below.

  In the example of FIG. 4, two loop heat pipes 1 are provided in the electronic device 2 corresponding to the two heat generating components 7, and each of the two heat generating components 7 is fixed to each evaporator 3 of the loop heat pipe 1. Yes.

  In this case, in order to reduce the size of the electronic device 2, the loop heat pipes 1 are provided in an overlapping manner in the electronic device 2.

  FIG. 5 is a perspective view of the loop heat pipe 1 provided in this manner.

  As shown in FIG. 5, in a layout in which two loop heat pipes 1 are overlapped, an intersection A where these loop heat pipes 1 intersect with each other occurs. At the intersection A, the two evaporators 3 are arranged in the same plane by providing a step in the steam pipe 5 and the liquid pipe 6 of one loop heat pipe 1, thereby reducing the thickness of the electronic device 2.

  However, if a step is provided in this way, the flow of the working fluid C is stagnated at the intersection A, and the heat transport capability of the loop heat pipe 1 provided with the step is reduced.

  In addition, in this example, since the condensers 4 of the two loop heat pipes 1 overlap each other, the heat of one condenser 4 heats the other condenser 4, and the heat dissipation efficiency of each condenser 4 is poor. turn into.

  Further, when the two loop heat pipes 1 are crossed in this way, the following problem also occurs.

  6 is a cross-sectional view for explaining another problem occurring at the intersection A, and corresponds to a cross-sectional view taken along the line II-II in FIG.

  As shown in FIG. 6, at the intersection A, the liquid tubes 6 of the two loop heat pipes 1 intersect with each other. In order to reduce the thickness of the electronic device 2, it is preferable that these liquid pipes 6 are brought into close contact with each other. However, a gap S is generated between the liquid pipes 6 due to a manufacturing error or the like. The thermal resistance during the rise.

  As a result, a temperature difference appears in the liquid-phase working fluid C flowing through each liquid pipe 6, and it becomes difficult to uniformly cool the two heat generating components 7 with the working fluid C.

  Hereinafter, this embodiment will be described.

(First embodiment)
FIG. 7 is a plan view of the electronic apparatus according to the present embodiment.

  The electronic device 20 is a small electronic device such as a smartphone, a digital camera, and a tablet terminal, and includes a housing 21 and first and second heat generating components 22 and 23 housed therein.

  Each of the heat generating components 22 and 23 is an active element such as a CPU that generates heat during operation, and is cooled by a loop heat pipe 24.

  The loop heat pipe 24 is produced by laminating a plurality of metal sheets as will be described later, and each has a loop-shaped first flow path 25 and a second flow path 26 in plan view.

  The first flow path 25 and the second flow path 26 are independent flow paths, and the first working fluid C1 and the second working fluid C2 are enclosed in each of them.

  A first evaporator 31 fixed to the first heat generating component 22 is provided in the middle of the first flow path 25. The fixing method is not particularly limited, but in this example, the first heat generating component 22 is connected to the first evaporator 31 via a TIM (Thermal Interface Material) (not shown).

  The first evaporator 31 generates the first vapor Cv1 of the first working fluid C1 by evaporating the first working fluid C1 with the heat of the first heat generating component 22. The first vapor Cv 1 reaches the condenser 27 through the first vapor pipe 33 provided in the first flow path 25.

  The condenser 27 has a planar shape that overlaps each of the first flow path 25 and the second flow path 26, and the first working fluid C1 and the second working fluid C2 are exchanged by heat exchange with the outside air. Cool to liquefy them. In order to promote heat exchange with the outside air, it is preferable to increase the surface area of the condenser 27 by making the condenser 27 rectangular in plan view.

  Then, the first working fluid C1 liquefied in the condenser 27 returns to the first evaporator 31 again through the first liquid pipe 34 provided in the first flow path 25.

  On the other hand, in the middle of the second flow path 26, a second evaporator 35 fixed to the second heat generating component 23 is provided. The manner of fixing is not particularly limited, and the second heat generating component 23 can be connected to the second evaporator 35 via a TIM (not shown) as with the first heat generating component 22.

  The second evaporator 35 evaporates the second working fluid C2 with the heat of the second heat generating component 23, thereby generating the second vapor Cv2 of the second working fluid C2. The second vapor Cv2 reaches the condenser 27 through the second vapor pipe 36 provided in the second flow path 26, and is then cooled and liquefied by the condenser 27.

  Then, the second working fluid C2 liquefied in the condenser 27 returns to the second evaporator 35 again through the second liquid pipe 37 provided in the second flow path 26.

  FIG. 8 is a perspective view of the loop heat pipe 24.

  As shown in FIG. 8, the flow paths 25 and 26 intersect at intersections B and C in a plan view.

  FIG. 9 is an exploded perspective view of the loop heat pipe 24 at the intersection B. FIG.

  As shown in FIG. 9, the loop heat pipe 24 is formed from a laminated body 44 in which first to third metal sheets 41 to 43 are laminated in this order. Although the material of each metal sheet 41-43 is not specifically limited, In this example, a copper sheet is used as each metal sheet 41-43.

  Instead of the copper sheet, a copper alloy sheet made of a stainless steel sheet or a copper alloy may be used as each of the metal sheets 41 to 43.

  Among these metal sheets 41 to 43, the second metal sheet 42 includes a first surface 42 a that faces the first metal sheet 41 and a second surface 42 b that faces the third metal sheet 43. Have.

  A first groove 42x that defines the upper inner surface of the first flow path 25 is formed in the first surface 42a. A second groove 42y that defines the lower inner surface of the second flow path 26 is formed in the second surface 42b.

  The first metal sheet 41 is formed with a third groove 41x that defines the lower inner surface of the first channel 25, and the upper inner surface of the second channel 26 is defined in the third metal sheet 43. A fourth groove 43x is formed.

  As a result, in the loop heat pipe 24, the first flow path 25 is formed between the first metal sheet 41 and the second metal sheet 42, and the second metal sheet 42 and the third metal are formed. The second flow path 26 is formed between the layers with the sheet 43.

  In order to prevent the channels 25 and 26 from being crushed, a rib structure or a porous structure may be provided inside these channels.

  Since these flow paths 25 and 26 are formed between the layers of the metal sheets 41 to 43, they have a flat cross-sectional shape suitable for reducing the thickness of the electronic device 20.

  In addition, by providing the portions where the flow paths 25 and 26 are provided as different layers of the metal sheets 41 to 43 as in this example, the flow paths 25 and 26 can be changed at the intersections B and C without providing a step. Roads 25 and 26 can be crossed. As a result, unlike the example of FIG. 4, it is possible to prevent the flow of the first working fluid C1 and the second working fluid C2 from stagnating at the steps of the flow paths 25 and 26.

  Although the site | part which provides the intersections B and C is not specifically limited, In this embodiment, the 1st liquid pipe 34 and the 2nd liquid pipe 37 are made to cross | intersect by planar view in the intersection B.

  As a result, heat exchange between the liquid-phase first working fluid C1 and the second working fluid C2 is promoted at the intersection B, so that the temperature difference between the liquid-phase working fluids C1 and C2 is reduced. The heat generating components 22 and 23 can be evenly cooled by C1 and C2.

  Further, it is preferable that an intersection C is provided in the condenser 27 and the first steam pipe 33 and the second steam pipe 36 are crossed at the intersection C in plan view.

  As a result, heat exchange between the first steam Cv1 and the second steam Cv2 is promoted through the second metal layer 42, so that the steam Cv1 and Cv2 can be cooled to the same degree in the condenser 27. It is possible to enhance the heat dissipation effect of the condenser 27.

  FIG. 10A is a cross-sectional view taken along the line II-II in FIG.

  As shown in FIG. 10A, a second metal sheet 42 is interposed between the first flow path 25 and the second flow path 26, and each flow is caused by the second metal sheet 42. The surfaces of the paths 25, 26 are defined.

  Therefore, there is no room for air to intervene between the flow paths 25 and 26 as in the example of FIG. 6, and the thermal resistance between the first flow path 25 and the second flow path 26 can be reduced. it can.

  In particular, by providing the second groove 42y in the second metal sheet 42, the bottom surface 42z of the second groove 42y is close to the first flow path 25, and the first flow path 25 and the second flow path are formed. The thermal resistance between the two is reduced.

  Therefore, the temperature difference between the first working fluid C1 and the second working fluid C2 in the liquid phase at the intersection B is further reduced, and the first heat generating component 22 and the second heat generating component 23 are evenly cooled. Can do.

  In the example of FIG. 10A, the height of the bottom surface 42z of the second groove 42y is set lower than the height of the second surface 42b, but the structure of the second metal sheet 42 is not limited to this.

  FIG. 10B is a cross-sectional view for explaining another structure of the second metal sheet 42, and corresponds to a cross-sectional view taken along the line II-II in FIG.

  As shown in FIG. 10B, in this example, the bottom surface 42z of the second groove 42y is provided in the same plane as the second surface 42b. Even if such a structure is adopted, since air is excluded from between the first flow path 25 and the second flow path 26, the thermal resistance between the flow paths 25 and 26 should be reduced. Can do.

  In FIGS. 10A and 10B, copper is used as the material for the first to third metal sheets 41 to 43. However, the present embodiment is not limited to this and is joined to each other. Each metal sheet 41-43 may be formed of a material that can be used.

  For example, copper may be used as the material of the first metal sheet 41 and the third metal sheet 43, and nickel copper alloy may be used as the material of the second metal sheet 42. Thus, by forming the second metal sheet 42 from a material different from that of the first metal sheet 41 and the third metal sheet 43, the thermal resistance between the flow paths 25 and 26 can be adjusted. It becomes.

  According to the loop heat pipe 24 according to the present embodiment described above, since the two evaporators 31 and 35 corresponding to the two heat generating components 22 and 23 are provided, each of the heat generated by one loop heat pipe 24 is generated. The parts 22 and 23 can be cooled simultaneously.

  And since the 1st flow path 25 and the 2nd flow path 26 are provided between the different layers of each metal sheet 41-43 as mentioned above, a level | step difference does not generate | occur | produce at the intersection of these flow paths 25 and 26. FIG. As a result, the flow of the first working fluid C1 and the second working fluid C2 can be prevented from stagnation due to the step, and as a result, the heat transport performance of the loop heat pipe 24 can be improved.

  Furthermore, since the condenser 27 is provided so as to overlap each of the two flow paths 25 and 26 in plan view, each of the first steam Cv1 and the second steam Cv2 flowing through the flow paths 25 and 26 is condensed into one. It can be cooled by the vessel 27. Therefore, it is not necessary to overlap two condensers as in the example of FIG. 5, and the condenser 27 can radiate heat from both surfaces, and the heat radiation efficiency of the condenser 27 can be increased.

  Next, a method for manufacturing the loop heat pipe 24 according to the present embodiment will be described.

  First, the processing method of the 1st metal sheet 41 is demonstrated.

  11 and 12 are plan views in the middle of processing the first metal sheet 41, and FIGS. 13 and 14 are sectional views thereof.

  Each of the cross-sectional views in FIGS. 13 and 14 corresponds to a cross-sectional view along each of the IV-IV line, the V-V line, and the VI-VI line in FIGS.

  First, as shown in FIGS. 11 and 13, a copper sheet having a thickness of 0.1 mm to 2.0 mm, for example, about 0.25 mm is prepared as the first metal sheet 41.

  And the 1st resist layer 51 is apply | coated to the surface of the 1st metal sheet 41, it exposes and develops, The opening 51a of the same planar shape as the 1st flow path 25 is made into the 1st resist layer. 51.

  Thereafter, the first metal sheet 41 is wet-etched to a depth of about 0.15 mm through the opening 51a, so that the third groove 41x having the same planar shape as the first channel 25 is formed in the first metal sheet 41. Form.

  Instead of wet etching, the third groove 41x may be formed by cutting the first metal sheet 41.

  The width of the third groove 41x is not particularly limited. In this example, the width W1 (see FIG. 13) of the third groove 41x in the portion that defines the first liquid pipe 34 is 6 mm. Further, the width W2 (see FIG. 13) of the third groove 41x at the portion defining the first steam pipe 33 and the portion passing through the condenser 27 is 7 mm.

  Furthermore, a plurality of vapor grooves 41d extending in the flow path direction are formed at intervals in the first metal sheet 41 corresponding to the first evaporator 31 by the etching described above. The steam groove 41d functions as a flow path through which the first steam Cv1 passes in the first evaporator 31, and has a depth of 0.15 mm and a width W3 (see FIG. 13) of about 1 mm.

  Further, as shown in FIG. 13, a plurality of fine channels 41e for holding the first vapor C1 in the liquid phase by a capillary force is formed between the adjacent vapor grooves 41d. The depth of the channel 41e is about 0.15 mm like the steam groove 41d. Further, the width W4 of the channel 41e and the interval p between adjacent channels 41e are both about 0.1 mm.

  After this etching is finished, the first resist layer 51 is removed.

  Next, as shown in FIGS. 12 and 14, the unnecessary processing on the first metal sheet 41 is completed by punching out unnecessary portions of the first metal sheet 41.

  The processing of the third metal sheet 43 is also performed by wet etching or cutting similar to the first metal sheet 41 described above, and the details thereof are omitted.

  FIG. 15 is a plan view of the third metal sheet 43 after the processing is completed, and FIG. 16 is a cross-sectional view thereof.

  Each cross-sectional view of FIG. 16 corresponds to a cross-sectional view taken along lines IV-IV, VV, and VI-VI in FIG.

  As shown in FIGS. 15 and 16, the third metal sheet 43 is a copper sheet having a thickness of 0.1 mm to 2.0 mm, for example, 0.25 mm. A fourth groove 43x having the same planar shape is formed.

  The width of the fourth groove 43x is not particularly limited, but the width W1 (see FIG. 16) of the fourth groove 43x in the portion that defines the second liquid pipe 37 is 6 mm. And the width W2 (refer FIG. 16) of the 4th groove | channel 43x of the part which demarcates the 2nd steam pipe 36, or the part which passes the condenser 27 is 7 mm.

  A plurality of vapor grooves 43 d extending in the flow path direction are formed in the third metal sheet 43 corresponding to the second evaporator 35 at intervals. The steam groove 43d functions as a flow path through which the second steam Cv2 passes in the second evaporator 35, and has a depth of 0.15 mm and a width W3 (see FIG. 16) of about 1 mm.

  As shown in FIG. 16, a plurality of fine channels 43e for holding the liquid-phase second working fluid C2 with a capillary force between adjacent vapor grooves 43d have a depth of about 0.15 mm. It is formed. The width W4 of the channel 43e and the interval p between adjacent channels 43e are both about 0.1 mm.

  Next, the processing method of the 2nd metal sheet 42 is demonstrated.

  17-19 is a top view in the middle of the process of the 2nd metal sheet 42, and FIGS. 20-22 is the sectional drawing.

  20 to 22 correspond to cross-sectional views taken along lines IV-IV, VV, and VI-VI in FIGS. 17 to 19, respectively.

  First, as shown in FIGS. 17 and 20, a copper sheet having a thickness of 0.1 mm to 2.0 mm, for example, about 0.4 mm is prepared as the second metal sheet 42.

  Then, the second resist layer 52 is applied to the first surface 42a of the second metal sheet 42, and is exposed and developed, so that the opening 52a having the same planar shape as the first flow path 25 is formed in the first surface. The second resist layer 52 is formed.

  Thereafter, the second metal sheet 42 is wet-etched to a depth of about 0.15 mm through the opening 52a, thereby forming the first groove 42x in the second metal sheet 42.

  Instead of wet etching, the first groove 42x may be formed by cutting the second metal sheet 42.

  As described above, the first groove 42x defines the first flow path 25 in cooperation with the third groove 41x (see FIG. 11), and the width of each part of the first groove 42x is as follows. The same as those of the third groove 41x. For example, the width W1 (see FIG. 20) of the first groove 42x in the portion that defines the first liquid pipe 34 is 6 mm. And the width W2 (refer FIG. 20) of the 1st groove | channel 42x of the part which demarcates the 1st steam pipe 33 and the part which passes the condenser 27 is 7 mm.

  After this etching, the second resist layer 52 is removed.

  Next, as shown in FIGS. 18 and 21, a third resist layer 53 is applied to the second surface 42 b of the second metal sheet 42. Then, the third resist layer 53 is exposed and developed to form an opening 53 a having the same planar shape as the second flow path 26 in the third resist layer 53.

  Then, the second groove 42y is formed in the second metal sheet 42 by wet etching the second metal sheet 42 to a depth of about 0.15 mm through the opening 53a.

  Note that the second groove 42y may be formed by cutting the second metal sheet 42.

  As described above, the second groove 42y cooperates with the fourth groove 43x (see FIG. 15) to define the second flow path 26, and the width of each part of the second groove 42y is as follows. The same as those of the fourth groove 43x.

  For example, the width W1 (see FIG. 21) of the second groove 42y in the portion that defines the first liquid pipe 34 is 6 mm. And the width W2 (refer FIG. 21) of the 2nd groove | channel 42y of the part which demarcates the 1st steam pipe 33 and the part which passes the condenser 27 is 7 mm.

  After this etching, the third resist layer 53 is removed.

  And as shown in FIG.19 and FIG.22, the process with respect to the 2nd metal sheet 42 is finished by punching the unnecessary part of the 2nd metal sheet 42. FIG.

  The subsequent steps will be described with reference to FIGS.

  FIG.23 and FIG.24 is a top view in the middle of manufacture of the loop heat pipe which concerns on this embodiment.

  First, as shown in FIG. 23, the first mesh member 55 is accommodated in the first groove 42 x of the second metal sheet 42. The first mesh member 55 is a metal mesh of fine metal wires, and fine holes are formed by the fine metal wires. In this example, the first mesh member 55 is formed by laminating three layers of wire mesh of copper wire having a diameter of 0.05 mm. Each wire mesh is formed with fine holes having an average diameter of 0.1 mm.

  Thereafter, the first metal sheet 41 is bonded to the first surface 42 a of the second metal sheet 42.

  Next, as shown in FIG. 24, the second mesh member 56 formed by laminating three layers of a copper wire wire mesh having a diameter of 0.05 mm is accommodated in the second groove 42y of the second metal sheet 42. . The diameter of the holes formed in the wire mesh is not particularly limited, but in this example, the average diameter is 0.1 mm.

  In this state, the third metal sheet 43 is bonded to the second surface 42 b of the second metal sheet 42.

  FIG. 25 is a cross-sectional view after finishing this process, and corresponds to a cross-sectional view taken along the line VI-VI in FIG.

  As shown in FIG. 25, the laminated body 44 by which the 1st-3rd metal sheets 41-43 were laminated | stacked by the process so far is obtained, and the condenser 27 is formed in a part of the laminated body 44. FIG.

  And these metal sheets 41-43 are joined by diffusion bonding by pressing each metal sheets 41-43, heating these metal sheets 41-43 at about 900 degreeC.

  After that, after reducing the pressure of each of the flow paths 25 and 26 from an injection port (not shown), water is injected into the first flow path 25 as the first working fluid C1, and the second flow path 26 is supplied with the second flow path. Water is injected as the working fluid C2.

  Thus, a thin loop heat pipe 22 having a thickness of about 0.9 mm is completed.

  According to the above-described manufacturing method of the loop heat pipe 22, the loop heat pipe 22 is created by joining the first to third metal sheets 41 to 43, and thus a flat flow suitable for the thin electronic device 20. Paths 25 and 26 can be obtained.

  Further, by accommodating the first mesh member 55 in the first flow path 25, the liquid phase first in the entire first flow path 25 in the initial state where heat is not applied to the first evaporator 31. The working fluid C1 permeates uniformly. Therefore, when the first heat generating component 22 generates heat under actual use, the first working fluid C1 can be evaporated regardless of the posture of the loop heat pipe 22, and cooling by the loop heat pipe 22 can be performed. It is possible to start.

  For the same reason, the cooling by the loop heat pipe 22 is started regardless of the posture of the loop heat pipe 22 by accommodating the second mesh member 56 in the second flow path 26. Can do.

(Second Embodiment)
In the first embodiment, the loop heat pipe provided with the two evaporators 31 and 35 to cool the two heat generating components 22 and 23 has been described, but the number of evaporators is not limited to this.

  In the present embodiment, a loop heat pipe provided with three evaporators corresponding to three heat generating components will be described.

  FIG. 26 is a plan view of the electronic apparatus according to the present embodiment.

  In FIG. 26, the same elements as those described in the first embodiment are denoted by the same reference numerals as those in the first embodiment, and the description thereof is omitted below.

  The electronic device 60 is a small electronic device such as a smartphone or a tablet terminal as in the first embodiment, and the casing 21 includes a first heat generating component 22, a second heat generating component 23, and a third heat generating component. The heat generating component 61 is accommodated.

  The third heat generating component 61 is an active element such as a CPU like the first and second heat generating components 22 and 23 and is cooled by the loop heat pipe 70.

  The loop heat pipe 70 has a third flow path 71 in addition to the first flow path 25 and the second flow path 26 described in the first embodiment. Among these, since the first flow path 25 and the second flow path 26 have been described in the first embodiment, the details thereof are omitted.

  The third flow path 71 is independent of each of the first flow path 25 and the second flow path 26 and has a loop-like planar shape. Further, water is sealed inside the third flow path 71 as the third working fluid C3.

  In the middle of the third flow path 71, a third evaporator 72 connected to the third heat generating component 61 via a TIM (not shown) is provided.

  The third evaporator 72 generates the third vapor Cv3 of the third working fluid C3 by evaporating the third working fluid C3 with the heat of the third heat generating component 61. The third steam Cv3 reaches the condenser 27 through the third steam pipe 73 provided in the third flow path 71.

  The condenser 27 has a rectangular planar shape that overlaps the third flow path 71, and cools and liquefies the third working fluid C3 by heat exchange with the outside air.

  The third working fluid C3 liquefied in the condenser 27 returns to the third evaporator 72 again through the third liquid pipe 74 provided in the third flow path 71.

  The loop heat pipe 70 can be manufactured by laminating the first to fourth metal sheets as follows.

  27 to 29 are plan views in the middle of manufacturing the loop heat pipe 70 according to the present embodiment.

  First, as shown in FIG. 27, a copper sheet is prepared as each of the first metal sheet 41 and the second metal sheet 42.

  On the surface of the first metal sheet 41, the third groove 41x described in the first embodiment is formed. The first groove 42x is formed on the first surface 42a of the second metal sheet 42, and the second groove 42y is formed on the second surface 42b.

  Then, after the first mesh member 55 is accommodated in the first groove 42 x, the first metal sheet 41 is bonded to the first surface 42 a of the second metal sheet 42.

  Next, as shown in FIG. 28, the second mesh member 56 is accommodated in the second groove 42 y of the second metal sheet 42.

  In addition to the second metal sheet 42, a copper sheet is prepared as the third metal sheet 43.

  The third metal sheet 43 has a third surface 43a that faces the second metal sheet 42 and a fourth surface 43b that faces the third surface 43a.

  Among these, the fourth groove 43x described above is formed in the third surface 43a. On the other hand, a fifth groove 43y that defines a third flow path 71 is formed in the fourth surface 43b.

  In the state where the second mesh member 56 is accommodated in the second groove 42y as described above, the third surface of the third metal sheet 43 is formed on the second surface 42b of the second metal sheet 42. 43a is pasted together.

  Subsequently, as shown in FIG. 29, the third mesh member 75 is accommodated in the fifth groove 43 y of the third metal sheet 43. Similar to the first mesh member 55 and the second mesh member 56, the third mesh member 75 is manufactured by laminating three layers of a copper wire wire mesh having a diameter of 0.05 mm. The diameter of the hole formed in the wire net is about 0.1 mm on average.

  The third mesh member 75 functions to hold the third working fluid C3 in the liquid phase in an initial state where heat is not applied to the third evaporator 72. Therefore, when the third heat generating component 61 generates heat under actual use, the third working fluid C3 evaporates regardless of the posture of the loop heat pipe 70, and cooling by the loop heat pipe 70 is started. Can do.

  In addition to the third metal sheet 43, a copper sheet having a thickness of about 0.25 mm is prepared as the fourth metal sheet 77.

  On the surface of the fourth metal sheet 77, a sixth groove 77x that defines the third flow path 71 in cooperation with the fifth groove 43y is formed.

  Then, the fourth metal sheet 77 is bonded to the fourth surface 43 b of the third metal sheet 43 in a state where the third mesh member 75 is accommodated in the fifth groove 43 y as described above.

  FIG. 30 is a cross-sectional view after finishing this step, and corresponds to a cross-sectional view taken along the line VI-VI in FIG.

  As shown in FIG. 30, the laminated body 80 by which the 1st-4th metal sheets 41-43, 77 were laminated | stacked by the process so far is obtained.

  And these metal sheets 41-43, 77 are joined by diffusion bonding by pressing each metal sheets 41-43, 77 while heating these metal sheets 41-43, 77 to about 900 degreeC. .

  After that, after reducing the pressure of each flow path 25, 26, 71 from an unillustrated inlet, water is injected into each of these flow paths 25, 26, 71 as first to third working fluids C1-C3. .

  As described above, the loop heat pipe 70 according to the present embodiment is completed.

  According to the above-described embodiment, the loop heat pipe 70 is provided with the first to third flow paths 25, 26, 71 corresponding to the first to third heat generating components 22, 23, 61. The three heat generating parts 22, 23, 61 can be simultaneously cooled by one loop heat pipe 70.

  As mentioned above, although each embodiment was described in detail, each embodiment is not limited to the above. For example, the widths of the first to third flow paths 25, 26, 71 are not limited to the above, and can be appropriately optimized according to the heat transport performance required for the loop heat pipes 24, 70.

  The following additional notes are disclosed for each embodiment described above.

(Additional remark 1) The laminated body in which the 1st metal sheet, the 2nd metal sheet, and the 3rd metal sheet were laminated in order,
A loop-shaped first flow path provided between the first metal sheet and the second metal sheet and enclosing a first working fluid;
A first evaporator provided in the middle of the first flow path for evaporating the first working fluid;
A loop-shaped second flow path provided between the second metal sheet and the third metal sheet and enclosing a second working fluid;
A second evaporator provided in the middle of the second flow path for evaporating the second working fluid;
A condenser that is provided in a part of the laminate and that condenses the first working fluid and the second working fluid;
Having a loop heat pipe.

  (Supplementary note 2) The loop heat pipe according to supplementary note 1, wherein the first flow path and the second flow path intersect in a plan view.

(Supplementary Note 3) The second metal sheet has a surface facing the third metal sheet,
The height of the bottom face of the second groove is equal to or less than the height of the surface at a portion where the first flow path and the second flow path intersect with each other. Loop heat pipe.

(Supplementary Note 4) The first flow path includes a first steam pipe through which the first working fluid evaporated by the first evaporator flows.
The second flow path has a second steam pipe through which the second working fluid evaporated by the second evaporator flows,
The loop heat pipe according to appendix 2, wherein in the condenser, the first steam pipe and the second steam pipe intersect in a plan view.

(Supplementary Note 5) The first flow path includes a first liquid pipe through which the first working fluid condensed by the condenser flows.
The second flow path has a second liquid pipe through which the second working fluid condensed by the condenser flows,
The loop heat pipe according to appendix 2, wherein the first liquid pipe and the second liquid pipe intersect each other in plan view.

(Supplementary Note 6) The second metal sheet has a first surface facing the first metal sheet and a second surface facing the third metal sheet,
The loop heat pipe according to claim 1, wherein the first surface defines an inner surface of the first flow path, and the second surface defines an inner surface of the second flow path.

(Additional remark 7) The 1st groove | channel which demarcates a part of said 1st flow path is formed in the said 1st surface,
The loop heat pipe according to appendix 6, wherein a second groove that defines a part of the second flow path is formed on the second surface.

(Additional remark 8) The 4th metal sheet laminated | stacked on the said 3rd metal sheet,
A third flow path having a loop-like planar shape formed between the third metal sheet and the fourth metal sheet, in which a third working fluid is enclosed;
The loop heat pipe according to appendix 1, further comprising a third evaporator provided in the middle of the third flow path and evaporating the third working fluid.

  (Supplementary note 9) The loop heat pipe according to supplementary note 1, wherein the condenser overlaps each of the first flow path and the second flow path in a plan view.

(Additional remark 10) The laminated body in which the 1st metal sheet, the 2nd metal sheet, and the 3rd metal sheet were laminated in order,
A loop-shaped first flow path provided between the first metal sheet and the second metal sheet and enclosing a first working fluid;
A first evaporator provided in the middle of the first flow path for evaporating the first working fluid;
A loop-shaped second flow path provided between the second metal sheet and the third metal sheet and enclosing a second working fluid;
A second evaporator provided in the middle of the second flow path for evaporating the second working fluid;
A condenser that is provided in a part of the laminate and that condenses the first working fluid and the second working fluid;
A first heat generating component connected to the first evaporator;
A second heat generating component connected to the second evaporator;
Electronic equipment having

DESCRIPTION OF SYMBOLS 1 ... Loop heat pipe, 2 ... Electronic device, 3 ... Evaporator, 4 ... Condenser, 5 ... Steam pipe, 6 ... Liquid pipe, 7 ... Heat-generating component, 11 ... 1st copper sheet, 11a ... 1st groove | channel 12 ... 2nd copper sheet, 12a ... 2nd groove, 20 ... Electronic equipment, 21 ... Housing, 22 ... 1st exothermic component, 23 ... 2nd exothermic component, 24 ... Loop heat pipe, 25 ... 1st flow path, 26 ... 2nd flow path, 27 ... Condenser, 31 ... 1st evaporator, 33 ... 1st steam pipe, 34 ... 1st liquid pipe, 35 ... 2nd evaporator , 36 ... second steam pipe, 37 ... second liquid pipe, 41 ... first metal sheet, 41x ... third groove, 42 ... second metal sheet, 42a ... first surface, 42b ... first 2 surface, 42x ... 1st groove | channel, 42y ... 2nd groove | channel, 43 ... 3rd metal sheet, 43a ... 3rd surface, 43b ... 4th surface, 43x ... 4th groove | channel, 3y ... fifth groove, 44 ... laminate, 51 ... first resist layer, 51a ... opening, 52 ... second resist layer, 52a ... opening, 53 ... third resist layer, 53a ... opening, 55 ... First mesh member, 56 ... second mesh member, 60 ... electronic device, 61 ... third heat generating component, 70 ... loop heat pipe, 71 ... third flow path, 72 ... third evaporator, 73 ... 3rd steam pipe, 74 ... 3rd liquid pipe, 75 ... 3rd mesh member, 77 ... 4th metal sheet, 77x ... 5th groove | channel, 80 ... Laminate.

Claims (6)

A laminate in which a first metal sheet, a second metal sheet, and a third metal sheet are sequentially laminated;
A loop-shaped first flow path provided between the first metal sheet and the second metal sheet and enclosing a first working fluid;
A first evaporator provided in the middle of the first flow path for evaporating the first working fluid;
A loop-shaped second flow path provided between the second metal sheet and the third metal sheet and enclosing a second working fluid;
A second evaporator provided in the middle of the second flow path for evaporating the second working fluid;
A condenser that is provided in a part of the laminate and that condenses the first working fluid and the second working fluid;
Having a loop heat pipe.   The loop heat pipe according to claim 1, wherein the first flow path and the second flow path intersect in a plan view. The second metal sheet has a surface facing the third metal sheet;
3. The height of the bottom surface of the second groove is equal to or less than the height of the surface at a portion where the first flow path and the second flow path intersect. Loop heat pipe. The first flow path has a first steam pipe through which the first working fluid evaporated by the first evaporator flows.
The second flow path has a second steam pipe through which the second working fluid evaporated by the second evaporator flows,
The loop heat pipe according to claim 2, wherein in the condenser, the first steam pipe and the second steam pipe intersect in a plan view. The first flow path has a first liquid pipe through which the first working fluid condensed by the condenser flows.
The second flow path has a second liquid pipe through which the second working fluid condensed by the condenser flows,
The loop heat pipe according to claim 2, wherein the first liquid pipe and the second liquid pipe intersect in a plan view. A laminate in which a first metal sheet, a second metal sheet, and a third metal sheet are sequentially laminated;
A loop-shaped first flow path provided between the first metal sheet and the second metal sheet and enclosing a first working fluid;
A first evaporator provided in the middle of the first flow path for evaporating the first working fluid;
A loop-shaped second flow path provided between the second metal sheet and the third metal sheet and enclosing a second working fluid;
A second evaporator provided in the middle of the second flow path for evaporating the second working fluid;
A condenser that is provided in a part of the laminate and that condenses the first working fluid and the second working fluid;
A first heat generating component connected to the first evaporator;
A second heat generating component connected to the second evaporator;
Electronic equipment having

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