JP2010251677A - Heat sink - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technique for sequentially dissolving a plurality of latent heat storage agents, having different melting points to be melted at low temperatures with the heat of an heat-generating object, transmitting the heat to the other higher melting point latent heat storage agents while being circulated by convection due to its liquidation, and storing more heat in the solvents based on the melt, by filling the plurality of latent heat storage agents and a liquid having heat transmitting fine powder fillers dispersed therein, in a space of the body of a heat sink having a high thermal conductivity. <P>SOLUTION: A plurality of latent heat storage agents having different melting points between 0 and 130°C and a liquid having heat transmitting fine powder fillers dispersed therein are mixed and filled in a space of the body of a heat sink having a high thermal conductivity, and then the body is sealed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention mixes and fills a heat sink body space having high thermal conductivity with a plurality of different latent heat storage agents and a liquid in which a thermally conductive fine powder filler is dispersed, so that the heat generating body can be reduced in size and configuration as a whole. The present invention relates to a heat sink that can quickly store heat to cool a heating element, can be controlled at a relatively low temperature, and does not require forced cooling or the like.

  In recent years, performance improvement of electronic devices, particularly computers and LED lighting fixtures, has been remarkable, and accordingly, countermeasures against heat generation in the vicinity of CPUs and LED chips have become important. For example, in a personal computer, heat dissipation from a heating element is conventionally performed by transferring the heat to a heat sink and providing an air cooling fan to dissipate heat by forced air convection. A heat sink is a metal block with a large number of heat sink fins that has a large surface area.It is used by contacting and fixing to the heat generating part of the heat generating element, and dissipates the heat generated from the heat generating element into the air via the heat dissipating fins. The heating element is cooled. In recent years, a high-performance water-cooled heat sink directly attached to the CPU has also been proposed. Attempts have also been made to reduce the size of the heat exchange unit by transferring heat using a latent heat storage agent that melts at a relatively low temperature as a heat medium.

  However, in the case of the heat sink, since heat is transferred by natural convection of air, when a large amount of heat transfer is necessary, the number of radiating fins is increased and the size is increased. Although there is a means for forcibly cooling the heat of the radiating fin with an air cooling fan, there are problems such as an increase in installation space, noise, and power consumption. For those using latent heat storage agents, the latent heat storage agent has a large heat of fusion, but at room temperature it is solid and its thermal conductivity is low, so the movement of heat from the time of melting to the start of convection is slow. , It has a drawback that the heat of the heating element is not transmitted quickly.

  Conventionally, for example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2008-246719) discloses that “a thermal printer including a thermal head including a heating element and a head support member that supports the thermal head, the head support. A thermal printer in which a sheet-like heat storage member is attached to the other end of the part opposite to the one end where the thermal head is supported, and the thermal head is directly fixed to the head support part. Is provided.

  And in this patent document 1, “the heat storage member is composed of a latent heat type heat storage sheet in which a plurality of heat storage materials are added to a base material, and each of the heat storage materials melts when the absorbed heat reaches a predetermined temperature. The heat storage sheet is explained to store heat while being maintained at a constant temperature while each heat storage material is melted, and “the heat of the thermal head is used to store the air inside the thermal printer. Since it is stored in the sheet-like heat storage member via the heat conduction plate without heating, it is described that the thermal printer can be efficiently cooled without providing a cooling fan. "

  However, in this patent document 1, since the heat storage agent is fixed in the form of a sheet, since the amount of the heat storage agent is small, a large volume is required and temperature absorption from the heating element to the sheet is reduced. I can't do it quickly. In addition, as shown in Examples 1 and 2 in Table 1, the heat storage material of the heat storage sheet is melted so as to maintain the melting temperature (20 to 70 degrees) for a predetermined time from the melting temperature to the standby temperature as a thermal printer. The temperature is set, and the melting temperature of the heat storage material is not set in a wide temperature range (0 to 130 ° C.). In addition, since the material containing the heat storage material is in the form of a heat storage sheet, there is no space where liquid convection occurs, liquid convection is performed from low temperature, and the latent heat storage agent dissolved at low temperature liquefies and convects, resulting in local The heat of a large heating element cannot be diffused throughout the heat sink. Further, the heat does not quickly dissipate to the outside despite the low temperature, using the heat conductive fine powder filler that flows together with the liquid and quickly transferring heat to the container having high heat conductivity.

  Patent Document 2 (Japanese Patent Application Laid-Open No. 2008-193017) states that “a semiconductor element, a heat sink on which the semiconductor element is mounted, and the semiconductor so as to be located on the opposite side of the heat sink with respect to the semiconductor element. Semiconductor device cooling structure including a heat storage member including a latent heat storage agent attached to the device is described.

  And this patent document 2 states, “When the heat generation amount of the semiconductor element increases rapidly in a short time while the semiconductor element is constantly cooled by the heat sink, the heat generation is caused by the phase change of the latent heat storage agent. Therefore, the cooling performance of the semiconductor element can be improved while suppressing the heat sink from becoming too large.

  However, in this patent document 2, since a means for radiating heat above and below the semiconductor element is provided, the circuit design is greatly restricted. As long as a heat sink is used, the heat has the disadvantage of requiring the use of a fan when forced cooling is required. In addition, the heat storage member and the heat sink must be attached to the semiconductor element. Further, the latent heat storage agent is high, for example, Sn / Zn (melting point: 199 ° C.) or dissolved salt NaOH-KOH (melting point: 170 ° C.), and the heat storage member is also convectioned from a low temperature to a liquid, and the latent heat storage agent is dissolved at a low temperature. By liquefying and convection, the heat of the local heating element cannot be diffused throughout the heat sink. Moreover, it does not describe that the melting temperature of the heat storage agent is set in a wide temperature range (0 to 130 ° C.). Further, the heat is quickly transferred to a highly heat-conducting container using a heat conductive fine powder filler that flows together with the liquid, and the heat is not quickly dissipated to the outside at a low temperature.

  Further, Patent Document 3 (Japanese Patent Application No. 2008-265647, claims, specifications, drawings) submitted by one of the applicants of the present application states that “in the heat sink attached to the heat generating portion of the heat generating element, A heat storage resin that includes a latent heat storage material and is thermally conductive is attached to the radiating fin, and the heat storage resin body is integrated into a plate or block by kneading the latent heat storage material into the heat conductive resin. There is provided a heat sink which is molded and has a tip portion side of the radiating fin embedded in the heat storage resin body.

  And this patent document 3 explains that "the latent heat storage material is composed of a material that changes from a solid phase to a liquid phase or from a liquid phase to a gas phase in a range of 30 to 120 ° C". According to the results, the heat sink of the example was below 100 ° C. even after 180 minutes. Also, according to the results of Table 5, the heat sink was below 60 ° C. even after 180 minutes.

  However, in this patent document 3, there exists a problem which requires more than the same volume as the past. Also, since the latent heat storage material has a melting temperature of 30 ° C. and the latent heat agent is kneaded into the resin, the volume filling rate cannot be increased to 70% or more, and as a result, the size of the block containing the latent heat agent is high. Melting from a low temperature (0 ° C) will not cause convection, and the heat of the heating element will be melted sequentially from the latent heat storage agent that melts at a low temperature and liquefied to heat other high latent heat storage agents while convection. It cannot transmit and store more heat due to its melting. In addition, since the heat sink itself is not filled with a latent heat storage agent, the heat is quickly transferred from the thermally conductive fine powder filler that flows with the liquid to the heat sink container with high thermal conductivity, and quickly dissipated to the outside at a low temperature. I can't let you. Therefore, comparing the examples shown in Tables 4 and 5 of Patent Document 3 with the examples of the present invention, the examples of the present invention are 48 ° C. in 6 hours (Table 2) and 35 ° C. in 6 hours. It is understood that (Table 3) and the latent heat storage effect are further improved.

  As described above, in any of the above Patent Documents 1 to 3, the heat of the heating element is melted at a low temperature by filling a plurality of latent heat storage agents having different melting points and a liquid in which a thermally conductive fine powder filler is dispersed. The heat conduction fine powder that melts sequentially from the latent heat storage agent and transfers heat to other high latent heat storage agents while convection by liquefying, storing more heat by melting, and the heat flows with the liquid There is no description of a technique in which heat is quickly transferred from a filler to a heat sink container having high thermal conductivity and rapidly radiated to the outside at a low temperature.

  In addition, it dissolves from the low melting point latent heat storage agent and absorbs heat from the heating element in a wide temperature range. Therefore, there is no description that the latent heat storage agent can be individually handled in a necessary temperature range (0 ° C. to 130 ° C.) depending on the temperature of the heating element and the external environment temperature.

  In addition, the heat conductive fine powder filler that moves with the liquid of the latent heat storage agent that causes convection quickly moves the heat inside the latent heat storage agent and the heat sink container with different high melting points, so that the heat transfer of the heating element becomes faster. In addition, there is no description that it is possible to increase the amount of heat propagation inside and to quickly release the amount of heat propagation transmitted to the container to the outside in a large amount.

  Furthermore, the low boiling point solvent vaporizes near the melting temperature of the latent heat storage agent, promptly promotes the external transfer of heat as a vapor to the top of the container, cools and liquefies after the heat is taken away, and repeats this cycle Thus, apart from thermal diffusion by convection due to liquefaction of the latent heat storage agent, there is no description that the thermal diffusion is possible by liquefaction associated with evaporation of the low boiling point solvent and cooling at a container temperature close to the external temperature. That is, since the boiling point of the low boiling point solvent is in a temperature range that is not significantly different from the melting point of the latent heat storage agent, the vaporization of the low boiling point solvent becomes significant before and after the latent heat storage agent is liquefied. The heat is transferred to a container with high heat conductivity while absorbing the heat of the heat, which cannot be rapidly dissipated to the outside at a temperature lower than the boiling point of the low boiling solvent.

  JP 2008-246719 A   JP 2008-193017 A   Japanese Patent Application No. 2008-265647

  By sequentially filling the heat sink body space with high thermal conductivity with a plurality of latent heat storage agents with different melting points and a liquid in which heat conductive fine powder filler is dispersed, the latent heat storage agent that melts the heat of the heating element at a low temperature sequentially. It melts and liquefies to transfer heat to other high latent heat storage agents while convection and store more heat by melting. On the other hand, the heat is quickly transferred from the heat conductive fine powder filler flowing together with the liquid to the heat sink container having high heat conductivity so that the heat is quickly radiated to the outside at a low temperature. Furthermore, due to the latent heat storage effect and vaporization at a low temperature by the low boiling point solvent, a large amount of heat is quickly moved to suppress a temperature rise in the vicinity of the heating element and to be controlled within a predetermined temperature range.

  According to the first aspect of the present invention, a heat sink body space having high thermal conductivity is mixed and filled with a plurality of different latent heat storage agents having different melting points in the range of 0 to 130 ° C. and a liquid in which a thermally conductive fine powder filler is dispersed. A heat sink is provided.

  In this invention, the heat of the heating element is sequentially melted from the latent heat storage agent that melts at a low temperature and transferred to other high latent heat storage agents while convection by liquefying, and more latent heat is stored by the melting. Will be. On the other hand, the latent heat is quickly transferred from the heat conductive fine powder filler flowing together with the liquid to the heat sink container having high heat conductivity, and quickly dissipated to the outside at a low temperature. Therefore, when the heating element suddenly releases heat, the melting point of the latent heat storage agent is different, so that liquid convection is possible from low temperature, so that the latent heat storage agent dissolved at low temperature liquefies and convects. The effect of diffusing the heat of the local heating element throughout the heat sink can be obtained. Such heat is quickly released to the outside from the heat sink container having high heat conduction. In dissipating the local heat of the heat absorption part, rapid thermal diffusion was enabled by convection of the latent heat storage agent and the heat conductive fine powder filler.

  The invention according to claim 2 is characterized in that the plurality of latent heat storage agents having different melting points are at least one of inorganic hydrate salts, organic compounds, inorganic solid-liquid vapor phases, and dissolved eutectic salts, or a plurality of two or more. A heat sink according to claim 1 is provided.

  In the present invention, the heat generated by the heating element is dissolved from the low melting point latent heat storage agent and absorbs the heat of the heating element in a wide temperature range. Therefore, the latent heat storage agent can be individually handled in a necessary temperature range (0 ° C. to 130 ° C.) depending on the temperature of the heating element and the external environment temperature.

  Invention of Claim 3 provides the heat sink in any one of Claim 1 and Claim 2 in which the said heat conductive fine powder filler is chosen from at least any one of carbon and a metal fine powder. .

  In the present invention, the heat conductive fine powder filler that moves together with the liquid of the latent heat storage agent that causes convection quickly moves the heat into the latent heat storage agent and the heat sink container having different high melting points. Accordingly, the heat transfer of the heating element becomes quicker and the amount of heat propagation inside is increased, so that the amount of heat propagation transmitted to the container can be rapidly released to the outside in a large amount.

  Invention of Claim 4 WHEREIN: The said liquid contains at least any one or more of the liquid obtained from the low-boiling-point solvent, water, polyethyleneglycol, or the melted thing of inorganic salt hydrate, Any of Claim 1 thru | or 3 The heat sink as described above is provided.

  In the present invention, the individual liquids of the latent heat storage agent can be melted at each melting point and liquefied to perform convection heat diffusion. The low boiling point solvent evaporates in the vicinity of the melting temperature of the latent heat storage agent, promptly promotes the external transfer of heat as a vapor in the upper part of the container, and cools and liquefies after the heat is taken away. Then, this cycle is repeated. Therefore, apart from convection thermal diffusion due to liquefaction of the latent heat storage agent, thermal diffusion is possible by liquefaction associated with evaporation of the low boiling point solvent and cooling at a container temperature close to the external temperature.

  An embodiment for carrying out the present invention will be described with reference to FIG. Reference numeral 1 denotes an electronic component (heating element), and reference numeral 2 denotes a heat sink. The heat sink 2 is made of a material having excellent thermal conductivity such as aluminum and is attached to the heat generating portion of the electronic component 1. A space 2 a is formed in the heat sink 2, and the space 2 a has a thickness width D sufficient to allow liquid convection from a low temperature of a plurality of latent heat storage agents 3 having different melting points. This thickness width D requires 0.5 mm or more.

  The heat sink body space 2a having high thermal conductivity is sealed by mixing and filling a plurality of latent heat storage agents having different melting points in the range of 0 to 130 ° C. and a liquid in which a heat conductive fine powder filler is dispersed. The melting point is preferably in the range of 0 to 80 ° C, more preferably in the range of 0 to 60 ° C.

  The plurality of latent heat storage agents having different melting points are selected from at least one of an inorganic hydrate salt, an organic compound, an inorganic solid-liquid vapor phase, and a dissolved eutectic salt, or a plurality of two or more. Inorganic hydrate salts include calcium chloride hydrate, sodium sulfate hydrate, sodium thiosulfate hydrate, sodium acetate hydrate and the like. Examples of organic compounds include various paraffin N-decanes. The inorganic solid-liquid vapor phase is water. As the dissolved eutectic salt, sodium hydroxide-sodium nitrate, sodium chloride-potassium chloride-magnesium chloride and the like are used.

  The heat conductive fine powder filler is selected from one or more of carbon and metal fine powder. Aluminum, copper or the like is used as the metal fine powder.

  Further, the liquid is selected from liquids obtained by melting a low boiling point solvent, water, polyethylene glycol, or inorganic salt hydrate.

  The heat sink 2 main body container uses, for example, a metal having excellent thermal conductivity such as aluminum or copper, and is subjected to surface processing such as fins and embossing except for the contact portion with the heating element to increase the surface area. It is also possible to increase the exchangeability. A material that changes from a solid phase to a liquid phase and from a liquid phase to a gas phase is generally selected as the latent heat storage agent in the range of 0 ° C to 130 ° C.

  As an effect | action of the structure in the said embodiment, the mixture of the several latent heat storage agent and heat conductive fine powder filler from which melting | fusing point differs is sealed in a heat sink container with high heat conductivity, and the container inside is hold | maintained in liquid form from near normal temperature. As a result, heat from the heating element is quickly transferred to the latent heat storage agent, and each of the plurality of latent heat storage agents is liquefied by liquefying while the heat generation element absorbs heat sequentially as the temperature rises. Promote

  Also, the low boiling point solvent vaporizes near the melting temperature of the latent heat storage agent, promptly promotes the external transfer of heat as a vapor to the upper part of the container, cools and liquefies after the heat is taken away, and repeats this cycle .

  Therefore, a large amount of heat transfer is possible from near room temperature by using the large melting latent heat of multiple latent heat storage agents dispersed in the liquid, so it has a small volume and heat capacity compared to other heat sinks with fins, etc. It is possible to suppress the temperature in the vicinity of the large heating element to a predetermined temperature range. Further, the heat transfer to the inner wall of the heat sink container due to the vaporization of the low boiling point solvent suppresses the temperature of the heat sink itself below the boiling point.

    A plurality of latent heat storage agents having different melting points are inorganic salt hydrates such as sodium acetate trihydrate (melting point 58 ° C), sodium sulfate decahydrate (melting point 32 ° C), heat conductive fine powder filler (aluminum as carbon and metal powder) , Copper fine powder), liquid (water), and methanol as a low melting point solvent in a proportion shown in Table 1 were placed in a container of heat sink 2 made of aluminum having an internal volume of 250 cc and completely sealed. The surface temperature of the vicinity (4 cm away from the heating element) and the surface of the heat sink were measured while applying 10 W of heat. As a comparative example, an empty aluminum container was measured by the same method.

  Table 2 and graph 1 show the temperature (° C.) in the vicinity of the heat sink (heat sink surface) of the heat sink (Example 1) to which the 10 W heat generator was attached and the empty container (Comparative Example 1). Table 3 and graph 2 show the temperature (° C.) of the heat sink (Example 2) with a 10 W heating element and the wall surface (place 4 cm away from the heating element) away from the heating element of the empty container (Comparative Example 2). It was as follows. The liquid in which the latent heat storage agent: heat conduction fine powder filler is dispersed is preferably 100: 5 to 100: 70. More preferably, it is 100: 30-100: 50. The liquid: heat conduction fine powder filler is preferably 100: 5 to 100: 40. More preferably, it is 100: 10-100: 30.

Graph 1

Graph 2

  As apparent from Tables 2 and 3 and graphs 1 and 2, the temperature control in the heat sink 2 of Examples 1 and 2 is very good, and it is estimated that there is a possibility that the electronic device 1 may be adversely affected. It is understood that the temperature is not reached even after being allowed to stand at a temperature of 96 hours. On the other hand, the empty container reaches almost the same temperature as the heating element temperature. Further, the temperature of the heat sink on the wall surface away from the heat generating portion (location 4 cm away from the heat generating element) does not reach 50 degrees, and it can be sufficiently used from the viewpoint of safety without forced cooling.

The invention's effect

  In the present invention, the heat of the heating element is sequentially dissolved from the latent heat storage agent that melts at a low temperature and transferred to other high latent heat storage agents while convection by liquefying, and more latent heat is stored by the melting. Will be. On the other hand, the latent heat is quickly transferred from the heat conductive fine powder filler flowing together with the liquid to the heat sink container having high heat conductivity, and quickly dissipated to the outside at a low temperature. Therefore, when the heating element suddenly releases heat, the melting point of the latent heat storage agent is different, so that liquid convection is possible from low temperature, so that the latent heat storage agent dissolved at low temperature liquefies and convects. The effect of diffusing the heat of the local heating element throughout the heat sink can be obtained. Such heat is quickly released to the outside from the heat sink container having high heat conduction. In dissipating the local heat of the heat absorption part, rapid thermal diffusion can be achieved by convection of the latent heat storage agent and the heat conductive fine powder filler.

  Moreover, in this invention, it melt | dissolves from a low melting | fusing point latent heat storage agent with the heat | fever which the heat generating body emitted, and absorbs the heat | fever of a heat generating body in a wide temperature range. Accordingly, the latent heat storage agent can be individually handled in a necessary temperature range (0 ° C. to 130 ° C.) depending on the temperature of the heating element and the external environment temperature.

  Moreover, in this invention, the heat conductive fine powder filler which moves with the liquid of the latent heat storage agent which causes convection quickly moves heat into the latent heat storage agent and the heat sink container having different high melting points. Accordingly, the heat transfer of the heating element becomes quicker and the amount of heat propagation inside is increased, and the amount of heat propagation transmitted to the container can be quickly released to a large amount outside.

  Moreover, in this invention, the individual liquid of a latent heat storage agent can melt | dissolve in each melting | fusing point, can liquefy, and can perform the thermal diffusion by a convection. The low boiling point solvent evaporates in the vicinity of the melting temperature of the latent heat storage agent, promptly promotes the external transfer of heat as a vapor in the upper part of the container, and cools and liquefies after the heat is taken away. Therefore, apart from convection thermal diffusion due to liquefaction of the latent heat storage agent, thermal diffusion is possible by liquefaction associated with evaporation of the low boiling point solvent and cooling at a container temperature close to the external temperature.

  Schematic sectional view in which an electronic device (heating element) is attached to the heat sink of the present invention

1 Electronic equipment (heating element)
2 Heat sink 2a Sealed container space D of heat sink Thickness width

Claims (4)

  A heat sink in which a heat sink body space having high thermal conductivity is sealed by mixing and filling a plurality of latent heat storage agents having different melting points in the range of 0 to 130 ° C. and a liquid in which a thermally conductive fine powder filler is dispersed.   2. The plurality of latent heat storage agents having different melting points include at least one of an inorganic hydrate salt, an organic compound, an inorganic solid-liquid vapor phase, and a dissolved eutectic salt, or a plurality of two or more. Heat sink.   The heat sink according to any one of claims 1 and 2, wherein the thermally conductive fine powder filler is selected from at least one of carbon and metal fine powder.   The heat sink according to any one of claims 1 to 3, wherein the liquid is selected from at least one of liquids obtained by melting a low boiling point solvent, water, polyethylene glycol, or an inorganic salt hydrate.

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