JP6514572B2 - Thin plate heat pipe type heat diffusion plate - Google Patents

Description

  The present invention relates to a thin plate heat pipe type heat diffusion plate suitable for use to diffuse the heat of an electronic element which is a heating element in a portable information terminal such as a multi-functional mobile phone (smart phone) or a tablet type personal computer. It is a thing.

  In portable information terminals and electronic devices, the calorific value increases with an increase in the amount of information processing, and the temperature of electronic elements such as a CPU is prevented to prevent malfunction due to heat and a decrease in information processing speed. The need to curb the rise has increased. On the other hand, in order to improve portability, reduction in thickness, size and weight is required.

  Conventionally, various means for heat dissipation and cooling in this kind of information terminal and electronic equipment have been proposed. For example, in Patent Document 1, a graphite sheet is used as a means for diffusing the heat of the integrated circuit, and the heat is A portable terminal device using a battery as a heat receiving means is described. The graphite sheet is affixed to the back of the touch panel display and the integrated circuit and battery are placed in contact with the underside of the graphite sheet. The heat generated in the integrated circuit is transferred to the graphite sheet and diffused throughout the graphite sheet. Due to the large thermal capacity of the battery, the heat diffused by the graphite sheet is transferred to the battery, thereby suppressing the temperature rise of the integrated circuit and alleviating the heat spot.

JP 2014-22798 A

  In the configuration described in Patent Document 1, since the heat of the integrated circuit is diffused by the graphite sheet, it is possible to suppress that the heat is accumulated in the vicinity of the integrated circuit and the temperature of the heat spot is accordingly increased. it can. However, since the diffusion of heat by the graphite sheet is performed by the heat conduction of the graphite sheet itself, the amount of heat that can be diffused is not necessarily large enough. Therefore, in the current situation where the calorific value is increasing along with the high integration and capacity of integrated circuits and electronic devices etc., the thermal diffusion by the graphite sheet is not enough, and a new technology for thermal diffusion is available. There is probably room for development.

  The present invention has been made focusing on the above technical problems, is excellent in thermal conductivity, and is less restricted in the direction of heat diffusion and less bias, thus suppressing heat spots in portable terminals, portable electronic devices, etc. It is an object of the present invention to provide a thin plate heat pipe type heat diffusion plate suitable for the above.

The present invention provides a thin plate heat pipe type heat diffusion plate in which a working fluid that is heated, evaporated, dissipates heat and condenses is enclosed inside a thin plate-shaped container in order to achieve the above object. A plurality of upper and lower plates joined to each other, wherein at least one of the upper and lower plates is in communication with each other in a direction opposite to the other plate. A groove is formed, and a wick that generates a capillary force by allowing the working fluid in a liquid phase to penetrate into at least one groove of the plurality of grooves is disposed, and the wick and the other A gas-permeable intervening layer through which the working fluid in the vapor phase can pass is interposed between the plate and the at least one groove in which the wick is disposed, and a recess is formed, and the wick is fitted in the recess It has been And it is characterized in and.

  In the present invention, the wick and the breathable intervening layer are disposed along the longitudinal direction of the groove at the central portion in the width direction of the groove and in the vapor phase on both sides of the wick and the breathable intervening layer. A steam flow path may be formed through which the working fluid flows.

  In the present invention, the wick is formed of a porous sintered body having a large number of pores therein, and the air permeable intervening layer has a size of the opening of the sieve larger than the pores of the porous sintered body. It may be formed of a mesh material of

  In the present invention, any one of the plurality of grooves is formed in an annular shape, and the air permeable intermediate layer disposed inside the annular groove is a side wall surface or the inner side of the outer circumferential side of the annular groove. It may be positioned in contact with the circumferential wall.

  In the present invention, any one of the plurality of grooves is formed in an angular shape in which a corner portion is curved, and the air-permeable intervening layer disposed inside the angular groove is formed in the corner portion. It may be positioned in contact with the outer sidewall surface or the inner sidewall surface of the groove.

  In the present invention, the breathable intervening layer may be provided with a positioning projection which abuts against the inner wall surface of the groove in which the breathable intervening layer is disposed to determine the position of the breathable intervening layer.

  In the present invention, the container is formed in a thin rectangular parallelepiped shape, and the plurality of grooves include longitudinal grooves along the longitudinal direction of the container and lateral grooves intersecting the longitudinal grooves, and the wick and the air-permeable interposition The layer may be disposed only in the inside of the longitudinal groove and in the inside of the lateral groove located on both end sides in the longitudinal direction of the container.

In the present invention, the container is formed in a thin rectangular parallelepiped shape, and the plurality of grooves are formed on longitudinal grooves along the longitudinal direction of the container, lateral grooves intersecting the longitudinal grooves, and both end sides in the longitudinal direction of the container be located and a further transverse groove communicating with the longitudinal groove, wherein the wick and the air-permeable intermediate layer, and the inside of the longitudinal groove, prior SL other positioned at both ends in the longitudinal direction of the container only the inside of the transverse grooves may be arranged.

  According to the present invention, when heat is transferred to any portion of the upper plate or the lower plate and the temperature of the portion becomes high, the working fluid enclosed inside the groove evaporates. The vapor flows through the interior of the groove towards low temperature and pressure points. Since the plurality of grooves communicate with each other, the working fluid vapor flows in a wide range other than the place where the heat is input. Also, even if the upper plate and the lower plate are thinned so as to approach each other, the upper plate is not in direct contact with the wick, and the air-permeable interposing layer is sandwiched between the upper plate and the wick. That is, since the air passage is formed between the wick and the upper plate, not only the groove in which the wick is disposed, but the entire plurality of grooves communicate without being divided. As a result, the restriction of the flow direction and the flow position of the working fluid in the gas phase is reduced, so that the heat diffusibility becomes good and the heat can be well diffused over a wide range. The working fluid vapor that has flowed to a point where temperature and pressure are low dissipates heat to the outside and condenses, and the resulting liquid working fluid penetrates the wick. In the wick, where the evaporation of the working fluid occurs, a capillary force is generated due to the drop of the meniscus, and the capillary force causes the working fluid in the liquid phase to evaporate the working fluid due to the heat input from the outside. To reflux.

It is a figure showing an example of the present invention, and is a top view in the state where a part of upper board was removed. It is the arrow expanded sectional view which follows the II-II line of FIG. It is a figure which shows the other example of this invention, Comprising: It is an expanded sectional view similar to FIG. FIG. 10 is a plan view of the upper plate removed, showing another example of a structure for positioning a breathable intervening layer. It is the top view of the state which removed the upper board which shows the other example of the structure for positioning a breathable intervening layer. It is the top view of the state which removed the upper board which shows the example which has arrange | positioned the wick and the air-permeable intervening layer also to the horizontal groove. It is the top view in the state which removed the upper board which shows the wick and the other example which also arrange | positioned the wick and the air-permeable intervening layer also to the horizontal groove. It is the top view of the state which removed the upper board which shows the other example which also arrange | positioned the wick and the air-permeable intervening layer also to the horizontal groove.

  FIG. 1 shows an embodiment of the present invention, and the heat diffusion plate 1 shown here is formed in a thin rectangular parallelepiped shape (thin plate shape) having a rectangular shape in a plan view. The heat diffusion plate 1 has a heat pipe structure inside, and is formed into a hollow structure by the lower plate 2 and the upper plate 3. That is, the lower plate 2 and the upper plate 3 constitute a container of the heat pipe structure. As shown in FIG. 2 as a sectional view, a groove 4 is formed in the lower plate 2. The groove 4 may be formed by subjecting the lower plate 2 to processing such as etching, or an intermediate plate having a portion corresponding to the groove may be formed on a flat plate by bonding.

  A plurality of grooves 4 are formed, and in the example shown in FIG. 1, a plurality of substantially rectangular annular outer peripheral grooves 4a and a plurality of inner peripheral grooves 4a crossing and communicating with outer peripheral grooves 4a The vertical grooves 4b and the horizontal grooves 4c. The vertical grooves 4b are linear grooves formed along the longitudinal direction (vertical direction in FIG. 1) of the heat diffusion plate 1, and the horizontal grooves 4c are grooves formed so as to be substantially orthogonal to the vertical grooves 4b. It is. Therefore, the part located in the both ends of the longitudinal direction of a container among the outer peripheral grooves 4a can also be called horizontal groove, and the part located in the both ends in the width direction can also be called vertical groove. The grooves 4a, 4b and 4c have a substantially rectangular sectional shape and the same depth. The width of each groove 4a, 4b, 4c may be equal or different. In the example shown in FIG. 1, the widths of the outer peripheral groove 4a and the longitudinal groove 4b are the same, while the width of the lateral groove 4c is narrower than the widths of the outer peripheral groove 4a and the longitudinal groove 4b.

  The wick 5 is disposed inside the outer circumferential groove 4a and the longitudinal groove 4b (that is, inside the longitudinal groove 4b and the lateral grooves located at both ends in the longitudinal direction of the container). The wick 5 is a porous body for generating capillary force, and a porous sintered body obtained by sintering fine powder such as metal or ceramic can be used. The wick 5 has a width narrower than the width of the outer peripheral groove 4 a and the vertical groove 4 b and smaller (thin) than the depth of the outer peripheral groove 4 a and the vertical groove 4 b. In the outer peripheral groove 4a, the wick 5 is in contact with the side wall surface 6 outside the outer peripheral groove 4a, while in the vertical groove 4b, as shown in FIG. 2 in an enlarged manner, the width direction of the vertical groove 4b The wick 5 is arranged in the central part of the Since the width of the wick 5 is narrower than the widths of the outer peripheral groove 4a and the longitudinal groove 4b, a void along the wick 5 is formed inside the grooves 4a and 4b in any of the grooves 4a and 4b. A flow path (hereinafter referred to as a steam flow path) 7 of working fluid vapor whose void will be described later is formed. In the outer circumferential groove 4a, the steam flow channel 7 is formed on one side of the wick 5, and in the vertical groove 4b, the steam flow channel 7 is formed on both sides of the wick 5.

  A breathable intervening layer 8 is provided in a space between the wick 5 and the upper plate 3 which is generated due to the height (thickness) of the wick 5 being smaller than the depths of the outer peripheral groove 4 a and the longitudinal groove 4 b. The breathable intervening layer 8 is provided to prevent the wick 5 from dividing the groove 4 or the steam flow path 7 and is configured to allow the working fluid vapor to flow. For example, the air-permeable intermediate layer 8 can be constituted by a mesh material in which the size of the opening of the sieve is larger than the pores formed inside the wick 5. In addition, the air-permeable intervening layer 8 may be configured by a projection that functions as a post provided on the surface of the wick 5. The “sieve opening size” is the inner diameter or the inner diameter of the “sieve” portion of the mesh material through which the particles pass, and in the case of sorting the particles by the mesh material, the “sieve mesh” is passed Mean the size corresponding to the largest diameter of the particles.

  The air permeable intervening layer 8 made of a mesh material is disposed so as to cover the surface on the upper plate 3 side of the wick 5. Therefore, like the shape of the wick 5, the air-permeable intervening layer 8 has a lattice shape of the outer peripheral groove 4a and the longitudinal groove 4b. Also, the air-permeable interposing layer 8 is sandwiched and fixed between the wick 5 and the upper plate 3 and no joining means such as sintering is applied. The positioning of the breathable intervening layer 8 is carried out by fitting in the outer peripheral groove 4a. That is, the contour on the outer peripheral side of the breathable intermediate layer 8 is equal to the contour formed by the side wall surface 6 on the outer peripheral side of the outer peripheral groove 4a, and the outer peripheral surface of the breathable intermediate layer 8 corresponds to the side wall surface 6 of the outer peripheral groove 4a The position is determined by contact. Since the whole of the air-permeable interposing layer 8 is integrally formed, the air-permeable interposing layer 8 is also positioned inside the longitudinal groove 4b so as to be positioned substantially at the center of the longitudinal groove 4b in the width direction.

  The upper plate 3 is joined to the lower plate 2 and the groove 4 is sealed. In that state, the breathable intermediate layer 8 is sandwiched and fixed between the upper plate 3 and the wick 5. A working fluid (not shown) is enclosed in the inside of the groove 4 sealed by the upper plate 3 in a state where a non-condensable gas such as air is exhausted. The working fluid is a heat transport medium that transports heat in the form of latent heat by evaporation, and a fluid that evaporates and condenses in the operating temperature range of the heat diffusion plate 1 is employed. Specifically, water is common, and it is also possible to use alcohol etc. besides it. When water is used as the working fluid, the lower plate 2 and the upper plate 3 are preferably formed of a copper plate in consideration of the wettability, corrosion resistance, airtightness and the like of the working fluid, and further considering strength and rigidity, It is preferable to form by the clad material which laminated | stacked the copper plate and the stainless steel plate. The lower plate 2 and the upper plate 3 can be joined by diffusion bonding using silver or the like. Furthermore, in order to enclose the working fluid, a nozzle communicating with the groove 4 described above is provided, and the working fluid in a liquid phase is injected from the nozzle into the inside of the groove 4, and the working fluid is heated and evaporated in that state. As a result, the noncondensable gas such as air may be discharged together with the steam, and then the nozzle may be crushed and welded and sealed.

  The groove 4 closed by the upper plate 3 is a heat pipe structure because the working fluid is sealed in a state where the non-condensable gas is degassed as described above. Therefore, when a part of the thermal diffusion plate 1 is brought into contact with a heating element such as a computing element, the working fluid is heated and evaporated. The working fluid vapor flows through the above-described steam flow path 7 to a point where the temperature and pressure are low. Even if the steam flow path 7 is formed along the wick 5, the vapor flow path 7 is communicated with the air permeable intervening layer 8 without being divided by the wick 5. For example, although each horizontal groove 4c mentioned above crosses the vertical groove 4b, the wick 5 is arranged in the direction perpendicular to the vertical groove 4b at the intersection, but between the wick 5 and the upper plate 3 Since the breathable intervening layer 8 through which the working fluid vapor can flow is provided, the left and right horizontal grooves 4 c sandwiching the vertical groove 4 b are in a state of being communicated by the breathable intervening layer 8. Therefore, since the working fluid vapor can flow across the wick 5, it flows rapidly toward the low temperature and pressure points without being particularly restricted by the flow direction and path. Then, the working fluid vapor dissipates heat and condenses at a low temperature location. Thus, the heat of the heating element is carried and diffused by the working fluid throughout the heat diffusion plate 1. Such heat diffusion is carried out by the working fluid transporting heat as its latent heat, so it can diffuse more heat than mere heat conduction, so even if the heating value of the heating element is high, The temperature of the heat spot can be lowered. In particular, in the heat diffusion plate 1 described above, the restriction of the flow of the working fluid vapor is reduced by providing the air-permeable interposing layer 8, and the heat diffusion can be promoted, so the temperature of the heat spot is reduced more effectively. It can be done.

  The condensed working fluid penetrates the wick 5. At the point where the working fluid evaporates, the decrease of the meniscus generated in the void portion of the wick 5 increases the capillary force, resulting in the action of suctioning the working fluid in the liquid phase. The condensed working fluid is refluxed by this capillary force to the place where evaporation occurs. The working fluid in the liquid phase thus flows back through the interior of the wick 5, and a space through which working fluid vapor can flow is secured between the wick 5 and the upper plate 3 by the breathable intervening layer 8. Thus, the working fluid vapor is not impeded from flowing and diffusing to the above-described place where condensation occurs. The working fluid in the liquid phase, which is refluxed via the wick 5, receives the heat from the above-mentioned heating element, evaporates again, transports the heat in the form of its evaporation latent heat, and diffuses the heat to the whole of the thermal diffusion plate 1. As described above, in the heat diffusion plate 1 according to the present invention, the flow of the working fluid vapor is inhibited or suppressed by the wick 5 in addition to transporting the heat in the form of latent heat of the working fluid and diffusing it over a wide range. Because there is not, a large amount of heat can be spread quickly and widely. When used for information equipment such as a portable terminal having a high degree of integration of electronic parts and the like and a large amount of information processing, heat spots due to heat generation of the electronic parts and the like can be suppressed and the temperature can be lowered.

  The present invention is not limited to the above-described embodiment. For example, the shape of the groove 4 may be the shape shown in FIG. FIG. 3 shows an example of the vertical groove 4b in which the wick 5 is disposed, in which a recess 9 is formed at the center in the width direction, and the wick 5 is fitted in the recess 9. The air-permeable interposing layer 8 is disposed on the upper side of the recess 9, and the space portions on both sides of the air-permeable interposing layer 8 form the steam flow path 7. In the present invention, the configuration “a vapor flow channel through which the working fluid in the gas phase flows on both sides of the wick and the air-permeable intervening layer is formed” includes the configuration shown in FIG.

  Further, the means for positioning the breathable intervening layer 8 in the present invention may be a projection formed on a part of the outer peripheral portion of the breathable intervening layer 8. Examples are shown in FIG. 4 and FIG. The example shown in FIG. 4 is an example in which protrusions 8 a protruding outward are provided at four corner portions of the air-permeable intervening layer 8. The outer peripheral groove 4a, which is one of a plurality of grooves, has an angular shape in which a corner portion is curved, and the projecting portion 8a abuts against the inner surface of the corner portion of the outer peripheral groove 4a. 8 are diagonally constrained, positioned and fixed. The example shown in FIG. 5 is an example in which protruding portions 8 a protruding outward are provided at central portions of four sides of the air-permeable interposing layer 8. When the projection 8a abuts on the inner surface of the central part of four sides in the outer peripheral groove 4a, the breathable intervening layer 8 is restrained and positioned in a direction parallel to the longitudinal groove 4b and a direction parallel to the lateral groove 4c. ing.

  Of the structures shown in FIGS. 1, 4 and 5 for positioning and fixing the breathable intervening layer 8, in the structure shown in FIG. 1, the area in which the breathable intervening layer 8 contacts the side wall surface of the groove 4a is the largest. Therefore, the fixing strength of the breathable intervening layer 8 is high, and when the external force acts on the heat diffusion plate 1, the positional deviation of the breathable intervening layer 8 can be reliably prevented. Further, in the structures shown in FIGS. 4 and 5, the steam flow path 7 is made wider because the contact area between the breathable intervening layer 8 and the side wall surface of the groove 4a is smaller than that in the structure shown in FIG. Can. In the structure shown in FIG. 4 and the structure shown in FIG. 5, the flow of the working fluid vapor is different because the position at which the air-permeable intervening layer 8 is in contact with the side wall surface of the outer peripheral groove 4a is different. . Further, depending on the contact position of the heat generating body with respect to the heat diffusion plate 1 (the position of the heating portion of the heat diffusion plate 1), the flow method of the working fluid vapor is different. Therefore, the structure shown in FIG. 4 and the structure shown in FIG. 5 may be selected based on the smoothness of the flow of the working fluid vapor according to the position of the heating unit.

  In addition, since the breathable intervening layer 8 has an integral structure in which the whole is connected, when positioning and fixing the inside of the grooves 4a, 4b, 4c, as described above, the outer circumferential side of the breathable intervening layer 8 Instead of bringing the portion of the outer circumferential groove 4a into contact with the side wall surface 6 of the outer circumferential groove 4a, the inner circumferential portion of the breathable intermediate layer 8 is brought into contact with the inner circumferential side wall surface of any of the grooves 4a, 4b, 4c The sexing intervening layer 8 may be positioned and fixed.

  Furthermore, in the present invention, the wicks 5 may be disposed inside of all the grooves 4 and all the wicks 5 may be communicated or integrally formed. In that case, the breathable intervening layer 8 is disposed on the whole between all the wicks 5 and the upper plate 3. 6 to 8 show an example thereof, and the example shown in FIG. 6 is an example in which the wick 5 and the breathable intervening layer 8 are disposed in the lateral groove 4c in the configuration shown in FIG. 1 described above. The example shown in FIG. 7 is an example in which the wick 5 and the breathable intervening layer 8 are disposed in the lateral groove 4 c in the configuration shown in FIG. 4 described above. The example shown in FIG. 8 is an example in which the wick 5 and the breathable intervening layer 8 are disposed in the lateral groove 4 c in the configuration shown in FIG. 5 described above.

  In the configurations shown in FIG. 1, FIG. 4 and FIG. 5 described above, the wick 5 is disposed in the outer peripheral groove 4a and the longitudinal groove 4b, and the transport of heat in the longitudinal direction of the thermal diffusion plate 1 is promoted. Therefore, when the heating part is positioned in the longitudinal direction of the thermal diffusion plate 1, that is, when the heat is diffused in the longitudinal direction of the thermal diffusion plate 1, the thermal diffusion plate 1 having the structure shown in FIG. 1, FIG. 4 and FIG. Preferred. On the other hand, in the structure shown in FIG. 6 to FIG. 8, the heat diffusion can be promoted also in the width direction of the thermal diffusion plate 1 by the wick 5 disposed in the lateral groove 4c. Therefore, the thermal diffusion plate 1 having the structure shown in FIGS. 6 to 8 is suitable when the heating portion is provided at the central portion of the thermal diffusion plate 1 and heat is diffused in four directions.

  The "lower plate" and the "upper plate" in the embodiment described above are names given in the upper and lower relationship shown in the figure, and the heat diffusion plate 1 is incorporated in a portable terminal or the like and used in various postures Therefore, the "lower plate 2" described above may be located on the upper side in the direction of gravity. That is, in the present invention, the names "lower plate" and "upper plate" do not limit the configuration of the present invention. Therefore, the groove or the wick may be provided in any one of the "lower plate" and the "upper plate".

  DESCRIPTION OF SYMBOLS 1 ... Thermal diffusion plate, 2 ... Lower plate, 3 ... Upper plate, 4 ... Groove, 4a ... Peripheral groove, 4b ... Vertical groove, 4c ... Horizontal groove, 5 ... Wick, 6. Inner wall surface, 7 ... Steam flow path, 8 ... breathable intervening layer, 8a ... projection.

Claims (8)

In a thin plate heat pipe type heat diffusion plate in which a working fluid that is heated, evaporated, dissipates heat and condenses is enclosed inside a thin plate type container,
The container has an upper plate and a lower plate joined together.
A plurality of grooves are formed in the surface where at least one of the upper plate and the lower plate is opposed to the other plate, the grooves being in communication with each other.
A wick that generates a capillary force is disposed by causing the working fluid in a liquid phase to permeate into at least one of the plurality of grooves.
Between the wick and the other plate is interposed an air-permeable intervening layer through which the working fluid in the gas phase can pass ,
A recess is formed in the at least one groove in which the wick is disposed,
The thin heat pipe type heat diffusion plate, wherein the wick is fitted into the recess .
  The wick and the breathable intervening layer are disposed along the longitudinal direction of the groove at the central portion in the width direction of the groove, and the working fluid in the gas phase flows on both sides across the wick and the breathable intervening layer. The thin-plate heat pipe type heat diffusion plate according to claim 1, wherein a steam flow path is formed. The wick is formed of a porous sintered body having a large number of pores therein;
The thin-plate heat pipe type according to claim 1 or 2, wherein the air-permeable intervening layer is formed of a mesh material having an opening size larger than the pores of the porous sintered body. Thermal diffusion plate. One of the plurality of grooves is annularly formed,
The air-permeable intermediate layer disposed inside the annular groove is positioned in contact with the outer peripheral side wall surface or the inner peripheral wall surface of the annular groove. The thin plate heat pipe type heat diffusion plate according to any one of 3. Any one of the plurality of grooves is formed in an angular shape in which a corner portion is curved,
The air-permeable interposing layer disposed inside the rectangular groove is positioned in contact with an outer side wall surface or an inner side wall surface of the groove at the corner portion. 4. A thin plate heat pipe type heat diffusion plate according to any one of 3 to 3.   The air-permeable intermediate layer is provided with a positioning projection which abuts against the inner wall surface of the groove in which the air-permeable intermediate layer is disposed to determine the position of the air-permeable intermediate layer. The thin plate heat pipe type heat diffusion plate according to any one of 1 to 3. The container is formed in a thin rectangular shape,
The plurality of grooves include a longitudinal groove along the longitudinal direction of the container, a lateral groove intersecting the longitudinal groove, and other lateral grooves located at both ends in the longitudinal direction of the container and communicating with the longitudinal groove Including
Wherein the breathable intermediate layer wick, according to characteristics and the inside of the longitudinal grooves, that are disposed only on the inside of the front SL other lateral grooves positioned on both ends in the longitudinal direction of the container Item 4. A thin plate heat pipe type heat diffusion plate according to any one of Items 1 to 3.
The container is formed in a thin rectangular shape,
The plurality of grooves include longitudinal grooves along the longitudinal direction of the container, and lateral grooves intersecting the longitudinal grooves.
The thin heat pipe type heat diffusion plate according to any one of claims 1 to 3, wherein the wick and the air permeable intervening layer are disposed inside the longitudinal groove and the lateral groove.

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