JP2007129183A - Cooling member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new cooling mechanism which is closely attached without forming a gap acting as a heat resistance on a body to be cooled, can immediately radiate the heat transmitted from the body to be cooled to a cooling medium, and has a high exhaust heat efficiency. <P>SOLUTION: The cooling member 1 for cooling the body to be cooled 2 in contact therewith is composed of a porous body 3 whose at least side of surface contacting with the body to be cooled 2 has open holes, and the porous body 3 is elastically deformed to contact with the body to be cooled 2 without forming a gap, and a gas, such as an air, is passed into the open holes of the porous body 3 as a cooling medium to radiate it. Preferably, the porous body 3 of the cooling member 1 has a micro structure that many columns of diameter not more than 100 μm and of aspect ratio not less than 5 are located on a base material at a slant. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cooling member for cooling a heat generating portion of an electronic device such as a television, a projector, or a personal computer.

  Conventionally, an electron gun method using a cathode ray tube has been generally used as a method for projecting an image on a screen of a television (TV). However, this type of television uses a single electron gun to scan on a cathode ray tube, so when the screen is enlarged, the angle with respect to the outer periphery becomes tight and the screen is distorted, so there is a limit to the enlargement. In order to prevent this distortion of the screen, there is a method to keep the distance from the electron gun to the cathode ray tube constant by curving the screen, but the flat screen is easier to see especially on large TVs, and recently even small TVs are flat. Due to the popularity of screens, curved screens are not used in large screen televisions. In addition, a cathode ray tube television is very suitable for a large-screen television set in a living room of a general household because the thickness of the cathode-ray tube television increases greatly as the screen becomes larger.

  For this reason, rear projection (rear pro) televisions, liquid crystal televisions, plasma televisions (PDPs), etc. have been spotlighted as methods that can achieve a larger screen and thinner televisions, and are being replaced by conventional CRT televisions. In addition, a method for projecting an image using a projector on a large screen is becoming popular for home theater. Moreover, while screens and screens are getting larger in order to gain power, devices other than screens and screens are required to be thinner and lighter so as not to occupy indoor space. In addition, since it is difficult to appreciate when the light spreads and the screen becomes dark because of the large screen, there is a high demand for higher brightness.

  The above-mentioned rear pro TV is a method of projecting from the back to the screen using a projector, but by using one or more reflectors, the distance between the projector and the screen can be increased in a thin housing, so that the thickness is reduced. Is possible. The rear pro has also been projected on the screen from the back by the CRT method in the past, but recently it has been switched to the MD (Micro Display) method in order to reduce the thickness, weight and image quality. The MD system includes a transmission type liquid crystal system (HTPS) as an optical device, a reflection type DLP (Digital Light Processing) system, and an LCOS (Liquid Crystal on Silicon) system. .

  In the liquid crystal method and the PDP method, liquid crystal elements as small shutters corresponding to the number of pixels and small plasma electrodes are formed side by side on the screen, so they do not require a projection distance and remain thin. Easy to enlarge. Therefore, the above-mentioned liquid crystal televisions and plasma televisions, including rear professional televisions, are rapidly spreading as the favorite of large-screen televisions. On the other hand, along with the increase in the size of the screen, the amount of heat generated from the elements and the screen and the heat generation density are increased. In addition, when a large screen is projected with the same output, the amount of light per unit area is insufficient, so that generally the power consumption increases as the screen increases, and the amount of generated heat increases accordingly. As a result, if the heat is not efficiently discharged outside the system, the element and its peripheral devices are thermally deteriorated, and thus the necessity for efficiently exhausting heat is increasing.

  Also, with respect to personal computers, in order to process large volumes of information such as images at high speed, the MPU that is the center of the PCs is required to perform higher speed processing, and the number of clocks is increasing year by year. However, the heat generation amount of the MPU has become very large along with this, and the exhaust heat technology has not caught up with the excessive heat generation amount. Therefore, since the MPU element malfunctions due to its own heat generation, there is a situation in which development for increasing the number of clocks has to be temporarily stopped, and the need for a more efficient exhaust heat technology is increasing.

  As a recent cooling technique, Japanese Patent Application Laid-Open No. 2004-319942 discloses a heat sink using a metal foam for a heat radiating portion. However, since metal foam has countless pores inside, if it is used incorrectly, heat dissipation characteristics can be obtained, as well as foaming polystyrene with high thermal insulation performance due to internal pores. There is. Japanese Patent Laying-Open No. 2005-032881 discloses a porous heat radiator having a low porosity portion and a high porosity portion. However, since this porous body does not deform as exemplified by porous sintered bodies and ceramic fibers, it is difficult to directly contact the heat radiating portion without any gap.

JP 2004-319942 A JP 2005-032881 A

  As a recent TV exhaust heat technology, for example, in an LCD TV or plasma TV, an Al sheet is pasted on the back of the screen, heat is released to the back of the Al sheet, and then air is sent to the back of the Al sheet with a fan to dissipate it into the atmosphere. The system that releases heat to the outside through the gap of the housing is adopted. In the reflection system of rear professional televisions and projectors, an Al heat sink with an Al fin is pressed against the back surface of the optical chip, air is sent by a fan to cool the air, and heat is similarly released from the gaps of the housing to the outside.

  In rear-pro televisions and projectors, as the screen becomes larger, the total amount of heat increases, and light is concentrated on a small element (Micro Display) of about 10 to 20 mm square to form an image, which is then projected onto a large screen. The heat density concentrated on is very large. Therefore, it is particularly necessary to efficiently discharge the heat. However, in the transmissive HTPS system, the liquid crystal chip transmits light, and thus cannot be cooled by pressing the cooling module surface as described above. Therefore, the outer peripheral frame of the liquid crystal chip is composed of a high heat conductive metal such as Al or Mg, and heat is transmitted, this is air-cooled with a fan, and furthermore, a fin is attached to the outer peripheral frame to increase the air cooling effect. It is taken.

  In the DLP method, the back surface of the DLP chip is also water-cooled in a projector for a large screen for theater that is particularly heated. However, since turning water into the electric device operates in a state in which dangers such as a short circuit due to water leakage and deterioration of electric parts are always present, an air cooling method is desirable as much as possible. Moreover, even if the element is water-cooled, the liquid is rarely made disposable, and since it is used after being circulated, heat must be released to the atmosphere through a heat exchanger at a different location. A typical air cooling structure is indispensable.

  However, the method of removing heat from the elements and the like with the heat sink and fins and cooling with air using a fan has a limit in sufficiently cooling the heat generated as the screen size increases. That is, since the heat transmitted from the element or the like to the heat sink spreads to the peripheral members before being transmitted to the back surface of the heat sink, the temperature is lowered. Therefore, even if the back surface of the heat sink is cooled by a fan, only low cooling efficiency can be obtained. In addition, the air cooling by the fan scatters heat in the housing, and thus has a problem of easily affecting other components. Furthermore, the hot air coming out of the gap between the casings blows hot air on the person near the device and raises the temperature in the room, and thus has many unpleasant aspects. In addition, the wind noise of the fans was the biggest cause of discomfort when enjoying images in a quiet living room.

  In addition, since the ceramic substrate or package on which the element is mounted always has a warp during sintering and warps, for example, by about 0.1 to 0.15 mm, a gap is created by pressing a heat sink or the like. The remaining air has a very large thermal resistance. Therefore, a method has been adopted in which a flexible heat conductive sheet or compound resin having a thickness of 1 to 2 mm is sandwiched between a substrate, a package, or the like and a heat sink, and attached without a gap. Thermally conductive sheets and compounds are selected that have as high a thermal conductivity as possible, but they are still in the range of several W / m · K to 10 W / m · K, with a high thermal conductivity of 237 W / m · K. Even when 403 w / m · K of copper was used as the heat sink, the low thermal conductivity of the interface layer was rate-determining, and it was not possible to efficiently discharge heat.

  Also in desktop personal computers and notebook personal computers, the MPU cooling technology employs almost the same air cooling technology as the element cooling technology of rear professional televisions and projectors. That is, heat is transmitted to the Al heat sink via a heat conductive sheet or a heat conductive resin provided on the back of the MPU, and air is radiated by sending air from the back with a fan. However, the problem of low cooling efficiency and the problem that the sound of the fan and the exhaust heat from the housing become uncomfortable factors are the same, and the heat radiation cannot catch up with the increase in the heat generation amount of the MPU.

  In view of such a conventional situation, the present invention can attach closely to a cooled body such as ceramics without generating a gap that becomes a thermal resistance, and immediately transfers the heat transmitted from the cooled body to the refrigerant. An object of the present invention is to provide a new cooling mechanism that can dissipate heat and therefore has higher heat discharge efficiency than conventional cooling means such as a heat sink and a fan and that does not scatter hot air around.

  The object to be cooled has warps, undulations, surface roughness, etc. that cannot be completely suppressed.Therefore, a gap is generated on the contact surface with the cooling member, and the thermal conductivity of the gap becomes almost zero. This is a factor that greatly hinders conduction. For example, when parts having high rigidity are brought into surface contact with each other, even if the flatness is increased and the surface roughness is reduced, a completely flat surface cannot be obtained microscopically. As a result, the most protruding three points contacted and the other part floated, so the gap formed between the parts did not contribute to heat conduction and the cooling capacity had to be lowered.

  Therefore, conventionally, inevitably, gaps between parts have been filled with a polymer or organic sheet or grease that has a high effect of filling the space. However, these polymers and organic sheets and greases have a very low thermal conductivity, and even at a high thermal conductivity type, they are only about 5 W / m · K. Therefore, the gap is filled and there is no portion with zero thermal conductivity, but a layer with low thermal conductivity made of these polymer, organic sheet or grease is interposed between the parts, so the layer is A large thermal resistance hinders the improvement of the cooling capacity.

  In order to solve the above problems, the present invention is a cooling member that contacts and cools a cooled body, and at least a contact surface side with the cooled body includes a porous body having open pores. An object of the present invention is to provide a cooling member characterized by being elastically deformed and / or plastically deformed to come into contact with an object to be cooled and to allow a coolant to flow into open pores of a porous body.

  In the cooling member according to the present invention, the contact area occupied by the porous body except the open pore portion is in contact with the opposed area in the contact state of the cooled body and the porous body. The area is preferably 0.01% or more. In the cooling member according to the present invention, the porosity of the porous body is preferably 50% or more, and the thickness of the porous body is preferably 200 μm or more. It is preferable to form a plurality of concave and convex shapes in the porous body to disturb the flow of the refrigerant and promote heat dissipation. Furthermore, it is preferable that the porous body has an uneven shape with a depth of 10 times or less with respect to the thickness, since the effect of promoting heat dissipation is increased. Or it is preferable to form the plate-shaped body within the thickness of a porous body in the clearance gap inside the said porous body.

  Since the porous body is in contact with the body to be cooled without a gap, it has elastic deformation ability and / or plastic deformation ability, and the elastic deformation amount and / or plastic deformation amount is preferably 100 μm or more. However, particularly when the amount of warpage of the cooled object is small, the elastic deformability and / or the plastic deformability may be small correspondingly, as long as it is larger than the warped amount of the cooled object. The porous body is preferably made of a material having a thermal conductivity of 100 W / m · K or more. Further, the porous body is preferably made of a material having a Young's modulus of 150 GPa or less.

  In the cooling member according to the present invention, for example, when the warped body has a large warp, the gap between the contact surfaces of the porous body and the body to be cooled is filled with 50 μm or less due to the surface roughness. A thin intervening layer can be provided.

  In the cooling member according to the present invention, the porous body has a micro structure in which a large number of columnar bodies are arranged on a base material of the cooling member. In this case, the columnar body preferably has a diameter of 500 μm or less and an aspect ratio of 5 or more. It is preferable to form a plurality of branch bodies on the side surfaces of the columnar body because the surface area of heat radiation increases, the flow of refrigerant such as the atmosphere is disturbed, heat exchange efficiency is improved, and the amount of heat radiation is increased.

  Further, since the whole or a part of the columnar body includes a curve, the side surface of the columnar body comes into contact with the heating element to improve the contact area, and the entire columnar body receives a stress to provide cushioning properties. Since it can exhibit, it can avoid that stress concentrates on one part and it breaks, and it is preferable. A structure including a curve only on one side of the porous body may be used, but a structure including a curve on both sides is preferable because cushioning properties are improved and contact thermal resistance is reduced. Further, it is preferable that the whole or a part of the columnar body has a shape including a plurality of curves, a spiral shape, or an S-shaped structure, so that cushioning properties can be enhanced.

  In the cooling member according to the present invention, the porous body has a metal porous structure or a metal honeycomb structure. The porous body may have a structure in which metal wires or carbon fibers are entangled. In this case, it is difficult to control uniform cooling characteristics, but it is preferable because a porous body structure can be obtained at low cost. The porous body is preferably a resin whose surface is metallized, so that the porous body structure of the resin can be mass-produced at low cost by, for example, injection molding, and heat conduction can be carried by the metallized film. The resin is preferably a resin in which a metal or the like is dispersed so as to have a high thermal conductivity because the thermal conductivity effect is enhanced.

  In the cooling member according to the present invention, the refrigerant contact area in which the surface of the open pores of the porous body is in contact with the refrigerant is at least five times the opposed area in the contact state between the cooled object and the porous body. It is preferable. Further, it is desirable that the refrigerant is circulated in the open pores of the porous body by feeding or sucking out the refrigerant. It is preferable to cool by flowing a refrigerant on the back side of the porous body that is the opposite side of the contact surface with the body to be cooled, and the back side of the porous body that is the opposite side of the contact surface with the body to be cooled Further, it is more preferable that both the heat radiating surfaces can be utilized by cooling by flowing a refrigerant through both the porous body and the porous body. It is preferable to circulate the refrigerant into the open pores of the porous body by feeding or sucking out the refrigerant from one or a plurality of through holes provided on the back surface of the cooling member opposite to the contact surface with the body to be cooled. If the refrigerant is air, the air around the device can be used, which is preferable in terms of cost.

  Further, it is preferable that the surface of the porous body has an emissivity of 0.5 or more because cooling by radiation can be used together. Higher emissivity on the surface of the porous body is preferable, but metals such as copper and aluminum with high thermal conductivity generally have low emissivity, so heat dissipation occurs exclusively by heat conduction and convection, but the surface emissivity is high The heat radiation efficiency is improved by the synergistic effect of radiation and radiation. Since radiation is defined only by the material of the surface, the inside may be made of a metal with high thermal conductivity and the surface may be covered with a high radiation material. The material to be coated is preferably a material such as carbon or ceramic having a radiation rate of 0.5 or more from the viewpoint of the radiation rate. As a method for coating, general coating methods for the above materials, such as vapor deposition, sputtering, thermal spraying, slurry application and thermal reaction deposition, can be used.

  The porous body of the present invention can be composed of a material having a high thermal conductivity such as Cu of 403 W / m · K or Al of 236 W / m · K, and has a thermal conductivity of only about 5 W / m · K at the conventional level. Since the thermal resistance can be reduced as compared with the sheet, it is possible to have a high cooling effect by using a porous body instead of the conventional heat conductive sheet and cooling by sending a gas. Moreover, it is also possible to make the radiating fin on the back surface of the cooling member have a porous structure, so that the cooling device is thin as a whole.

  Moreover, it is preferable that the stress which presses a porous body with respect to a to-be-cooled body applies 1 g or more per porous body. If it is less than 1 g, the porous body is not sufficiently pressed against the object to be cooled, and the contact due to cushioning and surface deformation becomes insufficient. This is because the maximum value of the pressing amount needs to be within 80% of the total stress at which the object to be cooled breaks, and if it exceeds that, the probability that the object to be cooled will break increases. Furthermore, if the metal porous body has low oxidation resistance and corrosion resistance, a film with high oxidation resistance and corrosion resistance is formed on the surface to improve durability and increase product reliability. Is possible.

  According to the present invention, the porous body having the elastic deformability and / or plastic deformability of the cooling member adheres without gaps even when the cooling element such as the heating element or the substrate on which the heating element is warped. As a result, there is no bubble that becomes thermal resistance at the contact interface, and no material with low thermal conductivity is sandwiched between the contact interfaces, so that the heat of the object to be cooled can be efficiently transferred to the porous body. it can. And since a heat | fever transmitted to the porous body can be directly radiated to a refrigerant | coolant by the surface of an open pore by flowing a refrigerant | coolant in the open pore of this porous body, very high heat exhaustion efficiency can be obtained.

  Therefore, by using the cooling member of the present invention for electronic devices such as televisions, projectors, and personal computers that are the objects to be cooled, the heat of the objects to be cooled is extremely efficiently compared to conventional cooling means such as heat sinks and fans. It can dissipate and cool, can cope with the recent increase in the amount of heat generation, and can be used comfortably because hot air is not scattered around.

  For example, as shown in FIG. 1, the cooling member 1 according to the present invention includes a porous body 3 provided on the contact surface side with the body to be cooled 2, and a side opposite to the contact surface with the body to be cooled 2 (back side). It is comprised with the base material 4 located in this. In this case, it is preferable that the entire contact surface with the object to be cooled 2 is the porous body 3, and further, the entire cooling member 1 may be the porous body. In addition, since the porous body has elastic deformability and / or plastic deformability and can contact with the object to be cooled without any gaps due to its spring performance, there is no bubble remaining as a thermal resistance at the contact interface, and the object to be cooled is cooled. The heat of the body can be efficiently transmitted to the cooling member. In addition, since the porous body has open pores, the heat transferred from the object to be cooled to the porous body can be immediately radiated to the refrigerant on the surface of the open pores by flowing the coolant through the open pores.

  In order to efficiently transfer more heat from the body to be cooled to the cooling member, it is porous relative to the area of the part where the body to be cooled and the porous body face each other in a contact state (referred to as opposed area). It is desirable that the area (referred to as a contact area) occupied by a portion where the body is in contact with the object to be cooled except for the open pores is 0.01% or more. It should be noted that the open pores for allowing the coolant to flow are only required to be open at least on the outer peripheral surface of the porous body, and are not necessarily open on the contact surface between the porous body and the cooled object. The contact area may be the same (100%) as the facing area.

  The porous body preferably has a porosity of 50% or more and a thickness of 200 μm or more in order to ensure a sufficient refrigerant flow rate. However, when the porosity of the porous body exceeds 99%, the strength decreases, and when the thickness exceeds 10 mm, the pressure for circulating the refrigerant increases, which is not preferable. Further, it is preferable to form an uneven shape with a depth of 10 times or less with respect to the thickness of the porous body, because the flow of refrigerant such as the air is disturbed and heat dissipation is promoted. Furthermore, it is also preferable to form a plate-like body having a thickness within the thickness of the porous body in the gap between the porous bodies because the heat flow is promoted by disturbing the flow of the refrigerant such as the atmosphere.

  The plate-like body formed in the gap between the porous bodies has a surface roughness Ra of 0.01 μm or more, so that the refrigerant is disturbed by the solid / gas friction with the refrigerant, and heat dissipation is promoted. It is preferable because it becomes easy, and Ra is more preferably 0.1 μm or more because the effect becomes very large. Further, by setting the surface roughness Rmax of the plate-like body to 0.1 μm or more, it is preferable because the refrigerant is disturbed by the solid / gas friction with the refrigerant and heat dissipation is easily promoted. The effect becomes very large when it is 0.5 μm or more. In addition, since the porous diameter is thin, measurement of surface roughness is difficult with a stylus type roughness meter, but if a three-dimensional SEM (3D-SEM) capable of measuring surface roughness and waviness is used, it is non-contact. Thus, the surface roughness can be measured with high magnification and high accuracy.

  The amount of elastic deformation and / or plastic deformation of the porous body is preferably 100 μm or more because it can correspond to the normal warp amount of 100 μm of a general alumina package, and 150 μm or more is preferably 150 μm, which is the maximum warp amount. Is more preferable because it can also be used. The amount of pressing the porous body against the object to be cooled may be larger than the amount of warpage of the object to be cooled, and it is sufficient to press the porous body more than the maximum warpage amount by 50 μm or more. For example, the object to be cooled having a warp or swell of 100 μm at the maximum can be brought into contact with the porous body over the entire surface by being pressed by 150 μm or more. In addition, it is preferable to press the porous body against the object to be cooled as strongly as possible because the tip of the porous body is elastically deformed or plastically deformed to increase the substantial contact area and reduce the contact thermal resistance. If the pressing pressure becomes too large, the object to be cooled and the porous body will be damaged. Therefore, it is preferable to press within a range of 90% or less where the damage occurs.

  In addition, since the porous body is made of a material having a Young's modulus of 150 GPa or less, the spring performance by the elastic deformability and / or plastic deformability is improved, and the porous body can be brought into contact with the object to be cooled without any gap. This is preferable. Furthermore, the porous body is preferable because it is made of a material having a thermal conductivity of 100 W / m · K or more, so that the cooling can be efficiently performed. As a material for the porous body having such a high thermal conductivity, a material mainly composed of copper having a thermal conductivity of 403 W / m · K and aluminum having a thermal conductivity of 236 W / m · K is preferable. In addition, gold (Au) and silver (Ag) are preferable in terms of material characteristics because they have high thermal conductivity and deformability, but are not preferable from an industrial standpoint because they are considerably expensive in cost. The purity of the constituent material of the porous body is preferably 90% or more. If it contains impurities of 10% or more, the thermal conductivity inherent to the material is drastically reduced, and the extensibility for expanding the substantial contact area when pressed against the heating element is also reduced, so that the contact thermal resistance is reduced. This is because it increases.

  By setting the surface roughness Ra of the porous body to 0.01 μm or more, it is preferable because the refrigerant is disturbed by the solid / gas friction with the refrigerant and heat dissipation is facilitated, and more preferably 0.1 μm or more. If it is, the effect will become very large. Further, the surface roughness Rmax of the porous body is also preferably 0.1 μm or more, because the refrigerant is disturbed by the solid / gas friction with the refrigerant and heat dissipation is easily promoted. When the thickness is 0.5 μm or more, the effect becomes very large. However, if the strength of the porous body is higher than 350 MPa, the cushioning property and the extensibility for expanding the substantial contact area when pressed against the heating element are lowered, and the contact thermal resistance is increased. Further, when the surface roughness Ra of the contact portion of the porous body is 10 μm or more, the contact area between the object to be cooled and the porous body becomes small and the thermal resistance becomes large, which is not preferable. If possible, Ra should be 1 μm or less. It is preferable to keep it at a minimum.

  In the cooling member according to the present invention, the area (referred to as the refrigerant contact area) where the open pore surface of the porous body is in contact with the refrigerant is more than 5 times the opposed area in the contact state between the object to be cooled and the porous body. It is preferable that In a conventional cooling structure, for example, an air cooling system in which air is sent to an Al fin attached to a cooled object by a fan, the fin area can be increased even if the area of the fin is increased five times or more than the opposed area of the cooled object and the fin. Since it was not possible to spread the wind to every corner of the surface with a fan, the actual cooling efficiency did not improve. However, by using a structure in which the coolant flows in the space formed by the open pores of the porous body like the cooling member of the present invention, the surface area in contact with the coolant can be increased, and the cooling efficiency is improved. Can do.

  It is preferable to circulate in the open pores of the porous body by sending or sucking out the refrigerant. In this case, cooling is performed by flowing a refrigerant from the back side of the porous body that is the opposite side of the contact surface with the cooled body, or the back side of the porous body that is the opposite side of the contact surface with the cooled body and It is possible to cool by flowing a refrigerant through both of the porous bodies. In this way, if the coolant is allowed to flow through both the back side of the porous body and the inside of the porous body for cooling, the heat radiation area can be increased, so that the cooling efficiency is improved. For example, it is preferable to flow air from the back surface of the porous body because the cooling efficiency is improved without providing a particularly large additional facility. In order to increase the cooling efficiency, air may be sent to the porous body in contact with the object to be cooled by a pump or a compressor, and air may be sent to the back side of the porous body by a fan.

When a gas such as air is used as the refrigerant, for example, by depressurizing the gas to 1 kgf / cm ² or less with a pump, the non-moving body film on the surface of the porous body or the cooling member is broken to prevent heat conduction during air cooling. Therefore, efficient cooling is possible. Moreover, since the inside of a porous body can be pressure-reduced, the close_contact | adherence degree of a to-be-cooled body and a cooling member can be raised, a thermal contact improves and heat transfer is accelerated | stimulated. In addition, when the gas is pressurized with a compressor, the number of gas molecules that receive heat per unit volume increases, so that the cooling efficiency is improved. In any case, it is preferable that the flow rate of the gas flowing in the open pores of the porous body is 0.05 m / second or more because the heat dissipation efficiency to the gas as the refrigerant is increased.

  In particular, when air is used as the refrigerant gas, it is preferable to reduce the pressure from a through hole provided on the back surface of the cooling member opposite to the contact surface with the object to be cooled. Even if air is allowed to flow from one end of the outer peripheral surface of the porous body to one end between the body to be cooled and the cooling member base material, the cooling effect can be obtained, but it is necessary to hermetically seal the open outer peripheral surface of the porous body It is difficult to match the elastic deformation of the porous body. For this reason, preferably, a through hole is provided at one or more central points on the back surface of the cooling member, and air is sucked from the outer peripheral surface of the open porous body by pulling the pressure from the through hole to the back surface side. The inside of the open pores of the material can be uniformly flowed and discharged from the through holes.

  The refrigerant flowing through the porous body may be gas or liquid. Liquid has the advantage of a high cooling effect, but electrical components are greatly damaged when a liquid leak occurs. In addition, if the liquid of the refrigerant is made disposable, the liquid cost and the liquid supply and drainage equipment costs increase, so normally the liquid is circulated and used. Must be released into the atmosphere. Therefore, also in the present invention, it is preferable to use a gas as the refrigerant. Specifically, nitrogen gas or argon gas can be used, but it is particularly preferable to use air because there is no risk of suffocation by the operator when it leaks to the outside.

  However, if the pressure loss in the porous body increases, and there are places where the pressure of the refrigerant such as air drops during evacuation or pressurization, the density of the number of molecules that receive heat will decrease, resulting in a decrease in cooling efficiency. Resulting in. Therefore, the cooling efficiency can be increased by creating a refrigerant flow in which the pressure loss inside the porous body does not increase. For example, when pumping from the back at one central point, the pressure near the central outlet is the lowest and the cooling efficiency in the central portion is reduced, but by making auxiliary holes to disperse the pressure around the pressure, Loss is reduced and cooling efficiency is improved. Furthermore, it is preferable to take measures such as alternately forming the air introduction part and the pumping part in the porous body because the pressure loss is further reduced and the cooling efficiency is improved.

  Also, the surface of the object to be cooled has minute irregularities, for example, irregularities of about 0.2 to 0.8 μm, depending on the surface roughness. When the porous body of the cooling member is pressed against the surface of the body to be cooled in this state, micropores remain at the contact interface between the two, resulting in thermal resistance. Therefore, an intervening layer is formed with thermally conductive grease or resin at the contact interface between the porous body and the object to be cooled so as to fill the uneven gap caused by the surface roughness of the object to be cooled. It has been found that by setting the thickness to 50 μm or less, the low thermal conductivity of the intervening layer does not become a thermal resistance, but rather can greatly improve the thermal conduction. If the thickness of the intervening layer exceeds 50 μm, it is not preferable because it acts as a thermal resistance due to the low thermal conductivity of the intervening layer.

  There is no particular limitation on the structure of the porous body in the cooling member of the present invention. For example, a metal porous body structure or a metal honeycomb structure such as a spring function for contacting the object to be cooled without gaps and a coolant flow for cooling. Any material having open pores may be used. As a particularly preferable porous body, for example, as shown in FIG. 2, there is one having a microstructure in which a large number of columnar bodies 3a are arranged on a base member 4 of a cooling member. Moreover, the porous body shown in FIG. 3 is provided with a collar portion 3b at the tip of the columnar body 3a in FIG. 2 to increase the contact area with the object to be cooled. In this microporous body, the spaces between the columnar bodies 3a are open pores.

  As shown in FIGS. 2 to 3, these columnar bodies are preferably arranged regularly in the XY direction on the surface of the substrate in an obliquely inclined state. The diameter of each columnar body is preferably 500 μm or less, and the aspect ratio of each columnar body is preferably 5 or more. By setting the diameter of the columnar body to 500 μm or less, the heat transmitted from the object to be cooled easily reaches the surface of the columnar body, and the heat dissipation effect for the refrigerant is enhanced. Further, by setting the aspect ratio of the columnar body to 5 or more, the elastic deformation of the porous body occurs smoothly, the degree of adhesion with the body to be cooled is improved, and the cooling efficiency is increased.

  The above-mentioned porous body having a microstructure composed of a large number of columnar bodies can be formed by a LIGA (Lithograph Galvanforming Abformug) method, MEMS, or nanoimprint. For example, according to the LIGA method, after applying and drying a resist on a metal plate serving as a base material, a mask having a pattern corresponding to the cross section of the columnar body is placed, and, for example, X-rays are irradiated from an oblique 45 ° direction. The resist is washed with a developer to remove the resist exposed to X-rays, the metal is filled in a columnar shape by electroplating in the space where the resist has been removed, and then the remaining resist is removed with oxygen plasma. A porous body having a microstructure (FIG. 2) composed of a large number of columnar bodies inclined in the direction is obtained. In addition, a metal foil is placed on the tips of these columnar bodies with silver brazing sandwiched between them, heat treated and joined, and then the metal foil is cut into a grid shape with a laser to provide a collar at the ends of the columnar bodies. A porous body having a microstructure (FIG. 3) can be obtained.

  Further, the porous body of the present invention may have a metal porous body structure or a metal honeycomb structure in addition to the above-described porous body made of a metal such as copper or aluminum. Alternatively, a resin whose surface is metallized, such as a porous fluororesin, can be used. The porous fluororesin has elastic deformability and / or plastic deformability, and can contact the object to be cooled without a gap by a spring function. In addition, although the porous fluororesin has a low thermal conductivity, it is possible to improve thermal conductivity characteristics by metallizing the surface with copper plating or the like. In addition, as a fluororesin, tetrafluoroethylene resin (PTFE), hexafluoroethylene copolymer (FEP), perfluoroalkoxyethylene copolymer (PFA), etc. are preferable from a viewpoint of cost and characteristic stability.

  By using the above-described cooling member according to the present invention, it is possible to efficiently exhaust heat from an object to be cooled such as an element, a substrate, and a package, and it is possible to prevent malfunction and deterioration of the element due to temperature rise. Therefore, it is suitable for use in many electronic devices, such as TVs and projectors that have increased in heat generation due to the recent increase in screen size, and personal computers that cannot keep up with the increase in heat generation due to the increased speed of MPU. be able to.

[Example 1]
As shown in FIG. 4, an AlN heater 5 having a length of 15 × width of 15 × thickness of 1 mm was used as a substitute for the DLP element, and this AlN heater 5 was made of Al with a purity of 92% length of 40 × width of 40 × thickness of 2.5 mm. _{The 2} O ₃ substrate 6 was bonded using Ag grease (thermal conductivity: 9 W / m · K). The cooling area at the center of the back surface of the Al ₂ O ₃ substrate 6 was 20 × 20 mm wide and warped 0.1 mm in a concave shape. The cooling member 1 in which the porous body 3 of Cu is formed on the Cu base 4 is disposed in the cooling region at the center of the back surface of the Al ₂ O ₃ substrate 6, and the back surface is centered on the back 20 × vertical 20 × width 20 ×. It was sandwiched between Cu substrates 7 having a protrusion with a thickness of 1 mm, and the whole was tightened with SUS screws.

The porous body 3 of the cooling member 1 was formed by the LIGA method. That is, a resist is applied and dried on the surface of a Cu plate having a length of 20 × 20 × 2 mm in thickness, and a mask is placed on the surface, irradiated with X-rays from an oblique direction of 30 °, washed with a developer, and exposed to X-rays. The resist was removed to a depth of 0.25 mm, Cu was filled in a columnar shape by electroplating in the space from which the resist was removed, and the remaining resist was removed by oxygen plasma. As shown in FIG. 2, the porous body of Sample 1 produced in this way has a number of columnar bodies 3a having a cross section of 25.times.25 .mu.m obliquely inclined at 30.degree. The contact area (corresponding to the total area of the tip portions of the columnar bodies arranged in a sword mountain shape) is 25 with respect to the area facing the Al ₂ O ₃ substrate 6 that is the object to be cooled. %Met.

In a state where the cooling system of Sample 1 is placed in a 300 × 300 × 600 mm case and is not affected by wind, the room temperature is controlled to 25 ° C. by air conditioning, and the power supplied to the AlN heater is set to 7 W. A cooling experiment was conducted. At that time, as shown in FIG. 4, a through hole 8 having a diameter of 2 mm is provided in the center of the Cu base 4 and the Cu substrate 7, and the pump 9 is pulled out of the casing through the stainless steel pipe from the back side of the porous body 3. Used to draw a vacuum at 1 kgf / cm ² . Air is sucked from the outer peripheral surface of the porous body 3 and flows into the central portion, and is discharged out of the casing through the through hole 8. At that time, air flowed at a flow rate of 3 liters / minute.

  Further, in place of the porous body of the sample 1, as shown in FIG. 3, a Cu foil having a thickness of 0.1 mm is placed on the tip of a columnar body 3a with a silver solder sandwiched between them, heat-treated, and then bonded. Then, by cutting the Cu foil into a grid, porous samples 2 to 4 having a micro structure in which the collar portion 3b was provided at the tip of the columnar body 3a were produced. However, the ratio of the contact area to the opposed area of the porous body to the object to be cooled is 25% for the sample 1, whereas the sample 2 is 12%, the sample 3 is 9%, the sample 4 is 2%, Sample 5 was 0.1%, sample 6 was 0.01%, and sample 7 was 0.005%.

  When the same cooling experiment as above was performed on the above samples 1 to 4, the temperatures measured by embedding the RTD element in the AlN heater were 35 ° C. for sample 1, 38 ° C. for sample 2, and 41 ° C. for sample 3. Sample 4 was 43 ° C., Sample 5 was 44 ° C., Sample 6 was 45 ° C., and Sample 7 was 47 ° C.

[Comparative Example 1]
As shown in FIG. 5, the same adhesive body of the AlN heater 5 and the Al ₂ O ₃ substrate 6 as in the first embodiment is used, and the cooling region at the center of the back surface of the Al ₂ O ₃ substrate 6 is 20 × 20 × width. A 1.5 mm heat conduction sheet (thermal conductivity: 30 W / m · K) 10 is disposed, and the back side of the Al fin 11 has a projecting portion 12 having a length 20 × width 20 × thickness 1 mm in the center on the back surface. The whole was clamped with SUS screws. The Al fin 11 was air-cooled by a fan 13 directly attached to the Al fin 11.

  The cooling system of this comparative example is placed in the housing in the same manner as in the first embodiment, and the room temperature is controlled to 25 ° C. by air conditioning in a state where it is not affected by the wind. Cooling experiment was conducted by setting the power supplied to the AlN heater to 7 W while exhausting heat. As a result, the temperature measured by embedding the RTD element in the AlN heater was 50 ° C.

[Example 2]
Although the porosity of the porous body in sample 1 of Example 1 is 75%, the porous bodies of samples 8 to 10 having different porosity are produced by changing the pitch of the columnar bodies constituting the porous body. did. The porosity of each sample was 52% for sample 8, 45% for sample 9, and 20% for sample 10.

  As a result of performing a cooling experiment on each of these samples by the same method as in Example 1, the temperature measured by embedding an RTD element in an AlN heater was 35 ° C. for sample 1 whereas 37 for sample 8 was 37 ° C. C., Sample 9 was 42.degree. C., and Sample 10 was 44.degree.

[Example 3]
Although the thickness of the porous body in Sample 1 of Example 1 was 250 μm, Samples 11 to 13 were produced in which the thickness of the porous body was changed. The thickness of the porous body of each sample was 400 μm for sample 11, 150 μm for sample 12, and 80 μm for sample 13.

  As a result of performing a cooling experiment on these samples 11 to 13 in the same manner as in Example 1, the temperature measured by embedding an RTD element in an AlN heater was 35 ° C. for sample 1 whereas sample 11 was measured. Was 32 ° C, Sample 12 was 44 ° C, and Sample 13 was 46 ° C.

[Example 4]
The elastic deformation amount of the porous body in the sample 1 of Example 1 is 120 μm, but the sample 14 having a different elastic deformation amount of the porous body is formed by forming a columnar body using Cu plates having different oxygen contents. ~ 16 were made. The amount of elastic deformation of the porous body of each sample was 200 μm for sample 14, 80 μm for sample 15, and 20 μm for sample 16.

  As a result of performing a cooling experiment on these samples 14 to 16 in the same manner as in Example 1, the temperature measured by embedding an RTD element in an AlN heater was 35 ° C. for sample 1 whereas sample 14 was measured. Was 33 ° C, Sample 15 was 42 ° C, and Sample 16 was 46 ° C.

[Example 5]
In the sample 1 of Example 1, the columnar body constituting the porous body had an aspect ratio of 10, but samples 17 to 19 having different aspect ratios were produced by changing the diameter of the columnar body. The aspect ratio of each sample was 20 for sample 17, 6 for sample 18, and 4 for sample 19. However, the thickness of the porous body was unified to 150 μm in all samples by changing the tilt angle of the columnar body.

  As a result of performing a cooling experiment on these samples 17 to 19 in the same manner as in Example 1, the temperature measured by embedding an RTD element in an AlN heater was 35 ° C. for sample 1 whereas sample 17 was measured. Was 31 ° C., Sample 18 was 39 ° C., and Sample 19 was 44 ° C.

[Example 6]
In Sample 1 of Example 1, the diameter of the columnar body constituting the porous body was 25 μm, but Samples 20 to 22 having different columnar body diameters were prepared. The diameter of the columnar body of each sample was 90 μm for sample 20, 120 μm for sample 21, and 150 μm for sample 22. However, the thickness of the porous body was unified to 150 μm in all samples by changing the tilt angle of the columnar body.

  As a result of performing a cooling experiment on these samples 20 to 22 in the same manner as in Example 1, the temperature measured by embedding an RTD element in an AlN heater was 35 ° C. for sample 1 whereas sample 20 was measured. Was 38 ° C., Sample 21 was 41 ° C., and Sample 22 was 43 ° C.

[Example 7]
In the sample 1 of Example 1, the ratio of the refrigerant contact area where the porous body contacts the refrigerant air with respect to the opposed area of the porous body and the cooled object is 11, but the porous body is configured. Samples 23 to 25 having different ratios of the refrigerant contact area to the facing area were produced by changing the interval between the columnar bodies. The ratio of the refrigerant contact area to the facing area of each sample was 20 for sample 23, 7 for sample 24, and 4 for sample 25.

  As a result of performing a cooling experiment on these samples 23 to 25 in the same manner as in Example 1, the temperature measured by embedding an RTD element in an AlN heater was 35 ° C. for sample 1 whereas that for sample 23 was Was 32 ° C, Sample 24 was 39 ° C, and Sample 25 was 44 ° C.

[Example 8]
In the sample 1 of the first embodiment, the structure is structured such that air is sucked from the through hole provided at the central point on the back surface of the porous body to flow air into the porous body. Air was sucked from a total of five points of 1 mm diameter through holes provided at four corners of a 7 mm square. Further, in the sample 27, without providing a through hole on the back surface of the porous body, an O-ring is attached to the outer peripheral surface of the porous body to maintain airtightness, and 1 facing from one side of the outer peripheral surface of the porous body 1 The structure sucks air to the side.

  As a result of conducting a cooling experiment on these samples 26 to 27 in the same manner as in Example 1, the temperature measured by embedding an RTD element in an AlN heater was 35 ° C. for sample 1 whereas sample 26 was measured. Was 31 ° C. and Sample 27 was 39 ° C.

[Example 9]
Sample 1 of Example 1 has a structure in which air is sucked at 1 kgf / cm ² from the through hole provided at one central point on the back of the porous body and air is allowed to flow through the porous body. by the compressor through the through hole provided in the center-point of the body rear feeding air at 2 kgf / cm ^2, and by the nitrogen gas cylinder from the through hole provided in the center-point of the rear sample 29 in the porous body 2 kgf / cm ² N _Two gases were sent.

  As a result of performing a cooling experiment on these samples 28 to 29 in the same manner as in Example 1, the temperature measured by embedding an RTD element in an AlN heater was 35 ° C. for sample 1 whereas that for sample 28 was Was 36 ° C. and Sample 29 was 36 ° C.

[Example 10]
In sample 1 of Example 1 above, air flows through the open pores of the porous body at a flow rate of 3 liters / minute (0.31 m / second when converted to the flow velocity at the porous body inlet). However, the flow rate of air is changed by adjusting the flow rate with a valve. Sample 30 has a flow rate of 5 liters / minute (flow rate 0.52 m / second), sample 31 has a flow rate of 1.5 liters / minute (flow rate 0.16 m / second), For Sample 32, the rate was 0.7 liter / min (flow rate: 0.07 m / sec).

  As a result of performing a cooling experiment on these samples 30 to 32 in the same manner as in Example 1, the temperature measured by embedding an RTD element in an AlN heater was 35 ° C. for sample 1 whereas sample 30 was measured. Was 31 ° C., Sample 31 was 39 ° C., and Sample 32 was 46 ° C.

[Example 11]
In the sample 1 of Example 1, a Cu porous body was used, but in the sample 33, Al was used, in the sample 34 Ni was used, and in the sample 35, a SUS porous body was used. However, the porous body of each sample was a porous body having a micro structure in which the same number of columnar bodies as in Sample 1 were arranged in a sword mountain shape.

  As a result of performing a cooling experiment on these samples 33 to 35 by the same method as in Example 1, the temperature measured by embedding an RTD element in an AlN heater was 35 ° C. for sample 1 whereas sample 33 was measured. Was 38 ° C, Sample 34 was 47 ° C, and Sample 35 was 48 ° C.

[Example 12]
The same cooling system as Sample 1 of Example 1 was used, but with an Ag-containing grease (thermal conductivity: 7.5 W / m · K) interposed at the contact interface between the porous body and the Al ₂ O ₃ substrate. The pores resulting from the surface irregularities were filled, and samples 36 to 39 having different intervening layer thicknesses were produced. The thickness of the intervening layer of each sample was 2 μm for sample 36, 10 μm for sample 37, 45 μm for sample 38, and 60 μm for sample 39.

  As a result of performing a cooling experiment on these samples 36 to 39 in the same manner as in Example 1, the temperature measured by embedding an RTD element in an AlN heater was 35 ° C. for sample 1 whereas that for sample 36 was Was 30 ° C., Sample 37 was 32 ° C., Sample 38 was 33 ° C., and Sample 39 was 45 ° C.

[Example 13]
In the sample 1 of Example 1, a porous body in which a large number of columnar bodies made of Cu are arranged in a sword mountain shape is used. The porous bodies arranged in the above were used. Sample 41 has a Cu porous body with a pore size of 100 to 300 μm, sample 42 has a Cu plating with a thickness of 5 μm, and Ni has a pore diameter of 100 to 300 μm. Sample 43 has a Cu plating with a thickness of 1 μm. The porous tetrafluoroethylene (PTFE) and a Cu honeycomb structure having a thickness of 3.0 mm and a honeycomb diameter of 0.5 mm were used as the porous bodies, respectively.

  As a result of conducting a cooling experiment on these samples 40 to 44 by the same method as in Example 1, the temperature measured by embedding an RTD element in an AlN heater was 35 ° C. for sample 1 whereas that for sample 40 was Was 43 ° C, Sample 41 was 32 ° C, Sample 42 was 42 ° C, Sample 43 was 39 ° C, and Sample 44 was 37 ° C.

[Example 14]
The Cu foil having a thickness of 20 mm × 6 mm and a thickness of 0.1 mm was etched to obtain a Cu foil in which columnar bodies having a cross section of 100 × 100 × length of 1000 μm were arranged at 350 μm intervals on one side of the Cu foil. A Cu foil having a large number of columnar bodies on one side and a 20 × 5 mm and 0.1 mm thick Cu foil having no columnar bodies are alternately stacked and screwed, and then penetrated with a diameter of 2 mm in the center by electric discharge machining. A hole was made to prepare a porous body of Sample 45. A cooling experiment was carried out on the porous body in the same manner as in Example 1 above, and air was drawn from the back and air was flowed into the porous body at a flow rate of 5 liters / minute, and an RTD element was embedded in the AlN heater and measured. The resulting temperature was 34 ° C.

  Further, a Cu foil having a size of 20 mm × 21 mm and a thickness of 0.1 mm was etched to obtain a Cu foil in which columnar bodies having a cross section of 100 × 100 × length of 1000 μm were arranged at 350 μm intervals on one side of the Cu foil. A Cu foil having a large number of columnar bodies on one side and a Cu foil having a side of an irregular shape as shown in FIG. After that, a through hole having a diameter of 2 mm was formed in the center by electric discharge machining to produce porous bodies of samples 46 to 48. However, the curvature radius R of the unevenness was 1 mm for the sample 46, 9 mm for the sample 47, and 10 mm for the sample 48.

  For each of these samples, a cooling experiment was performed in the same manner as in Example 1 above. When air was drawn from the back and air was allowed to flow through the porous body at a flow rate of 5 liters / minute, an RTD element was embedded in the AlN heater. The measured temperatures were 29 ° C. for sample 46, 30 ° C. for sample 47, and 35 ° C. for sample 48.

[Example 15]
After forming a through hole with a diameter of 2 mm in the center of a 20 × 20 × 5 mm Cu plate, wire discharge machining was performed on the Cu plate, and the cross section was 100 × 100 μm with a 30 ° inclination angle and arranged at 350 μm intervals. A porous body of sample 49 having a body was formed. In addition, three through-holes with a diameter of 2 mm arranged in a line are opened, and then a wire discharge process is performed on the Cu plate to have a columnar body that has a cross section of 100 × 100 μm, an inclination angle of 30 °, and is arranged at intervals of 350 μm. A porous body of sample 50 was formed.

  When these samples were subjected to a cooling experiment by the same method as in Example 1, the temperatures measured by embedding an RTD element in an AlN heater were 34 ° C. for sample 49 and 33 ° C. for sample 50.

  In addition, four 0.1 × 20 × 0.7 mm plate-like bodies were inserted in the porous body of the sample 50, that is, between the columnar bodies excluding the through holes. The surface roughness Ra of the plate-like body of each sample was changed to 0.08 μm for the sample 51, 0.1 μm for the sample 52, and 0.5 μm for the sample 53.

  For each of these samples, a cooling experiment was performed in the same manner as in Example 1. As a result, the temperatures measured by embedding the RTD element in the AlN heater were 31 ° C. for sample 51, 30 ° C. for sample 52, and 53 ° for sample 53. It was 29 ° C.

[Example 16]
Cu used for the porous body of Example 15 has a purity of 99.96%. In Example 16, the manufacturing method and shape were the same as those of Sample 49 of Example 15, but a porous body was prepared using Cu with a purity of 92.5% for Sample 54 and 88% for Sample 55.

  When each of the above samples was subjected to a cooling experiment by the same method as in Example 1, the temperature measured by embedding an RTD element in an AlN heater was 34 ° C., whereas that of Sample 54 was 34 ° C. Was 37 ° C. and Sample 55 was 40 ° C.

[Example 17]
Cu used for the porous body of Example 15 has a tensile strength of 280 MPa. In this example 17, the manufacturing method and shape are the same as those of the sample 49 of the example 15, but a porous body is prepared using Cu having a tensile strength of 340 MPa for the sample 56, 380 MPa for the sample 57, and 420 MPa for the sample 58. did.

  For each of the above samples, a cooling experiment was performed in the same manner as in Example 1. As a result, the temperature measured by embedding the RTD element in the AlN heater was 34 ° C. for Sample 49, whereas Sample 56 was 36 ° C., Sample 57 was 40 ° C., and Sample 58 was 41 ° C.

[Example 18]
As the porous body of the sample 49 of Example 15, a columnar body having a surface roughness Ra of 0.1 μm was used. In this example 18, the manufacturing method and the shape are the same as those of the sample 49 of the example 15. However, by changing the surface etching conditions, the surface roughness of the sample 59 is 0.08 μm in Ra, and the sample 60 is 0.5 in Ra. The sample 61 was finished to 5 μm and Ra of 1.0 μm.

  For each of the above samples, a cooling experiment was performed in the same manner as in Example 1. As a result, the temperature measured by embedding an RTD element in an AlN heater was 34 ° C. for sample 49, whereas that for sample 59 was 36 ° C., Sample 60 was 40 ° C., and Sample 61 was 41 ° C.

[Example 19]
In the porous body of Sample 45 of Example 14, the surface roughness Ra of the columnar body in the Cu foil on which the columnar body was formed was 0.1 μm. In this example 19, the manufacturing method and the shape are the same as those of the sample 45 of the example 14, but when etching is performed to form the columnar body, a 0.05 × 0.1 mm branch body is formed on the side surface of the columnar body. Are etched into a shape in which four are added to the left and right respectively, and the surface roughness of the columnar body including the branch body is changed by changing the etching conditions to 0.08 μm for Ra in the sample 62 and 0.1 μm for Ra in the sample 63. In the sample 64, Ra was set to 0.5 μm.

  When each of the above samples was subjected to a cooling experiment in the same manner as in Example 1, the temperatures measured by embedding an RTD element in an AlN heater were 40 ° C. for Sample 62, 34 ° C. for Sample 63, and Sample 64. Was 32 ° C.

[Example 20]
In the porous body of the sample 45 of Example 14, a linear columnar body inclined on one side of the stacked Cu foil was formed. In Example 20, the manufacturing method and shape were the same as those of Sample 45 of Example 14, but the porous body was produced by changing the shape of the columnar body during the etching of the Cu foil.

  That is, in the sample 65, as shown in FIG. 7, a columnar body having a width of 100 μm, an outer diameter of 1 mm, one end integrated with the Cu foil of the base, and one end at a position of 0.8 mm from the Cu foil, They were formed at intervals of 35 mm. In Sample 66, as shown in FIG. 8, columnar bodies having an arch shape with a width of 100 μm and an outer diameter of 1 mm and integrated with Cu foil at both ends were formed at intervals of 0.2 mm. In sample 67, as shown in FIG. 9, columnar bodies having a shape including a plurality of curves having a width of 100 μm, a distance between both ends of 1 mm, and an outer diameter of 250 μm were formed at a center-to-center pitch of 700 μm. Further, in the sample 68, as shown in FIG. 10, S-shaped columnar bodies having a width of 100 μm and a distance between both ends of 1 mm were formed with a center-to-center pitch of 700 μm.

  For each of these samples, a cooling experiment was performed in the same manner as in Example 1. As a result, the temperatures measured by embedding the RTD element in the AlN heater were 31 ° C. for sample 65, 31 ° C. for sample 66, and 67 for sample 67. 30 ° C. and Sample 68 was 29 ° C.

[Example 21]
In the porous body of Sample 49 in Example 15, the surface roughness of the tip of the columnar body was 0.1 μm in Ra. In this Example 21, the manufacturing method and shape are the same as those of the sample 49 of Example 15, but the surface roughness of the tip of the columnar body is changed by changing the abrasive grain conditions on the Cu plate surface before wire electric discharge machining. In Sample 69, Ra was 1 μm, in Sample 70, Ra was 5 μm, in Sample 71, Ra was 7 μm, and in Sample 72, Ra was 9 μm.

  For each of these samples, a cooling experiment was performed in the same manner as in Example 1. As a result, the temperature measured by embedding the RTD element in the AlN heater was 34 ° C. for sample 49, while that for sample 69 was 36 ° C, Sample 70 was 37 ° C, Sample 71 was 40 ° C, and Sample 72 was 42 ° C.

[Example 22]
Instead of the columnar porous material in the sample 49 of Example 15, the sample 73 of Example 22 used a wool-like porous material in which 0.1 g of a 0.05 mm diameter Cu wire was entangled. In the sample 74, a sheet-like porous body in which 0.1 g of carbon fiber having a diameter of 0.05 mm is entangled is used. The porous bodies of Sample 73 and Sample 74 are sandwiched between a 20 × 20 × 5 mm Cu substrate and an Al ₂ O ₃ substrate each having a hole with a diameter of 2 mm at the center, and cooling similar to that in Example 1 is performed. A system was made.

  For each of these samples, a cooling experiment was performed in the same manner as in Example 1. As a result, the temperature measured by embedding the RTD element in the AlN heater was 34 ° C. for sample 49, while that for sample 73 was 38 ° C. and Sample 74 was 39 ° C.

[Example 23]
In the sample 49 of Example 15, the tightening force of the porous body having the columnar body was 20 g per columnar body. In Example 23, the tightening force was changed to 0.1 g for sample 75, 1 g for sample 76, 5 g for sample 77, 50 g for sample 78, and 100 g for sample 79.

  For each of these samples, a cooling experiment was performed in the same manner as in Example 1. As a result, the temperature measured by embedding the RTD element in the AlN heater was 34 ° C. for sample 49, while that for sample 75 was 41 ° C, Sample 76 was 39 ° C, Sample 77 was 37 ° C, Sample 78 was 30 ° C, and Sample 79 was 28 ° C.

[Example 24]
The porous body in the sample 49 of Example 15 was used, and in the sample 80, 17 20 × 1 × 50 mm Cu fins were brazed to the Cu plate on the back side thereof. In Sample 81, the same columnar body as the surface was formed on the back surface (20 × 20 mm) of the porous body of Sample 49. In these samples 80 and 81, the air in the porous body was decompressed at a rate of 5 liters / minute from the through hole having a diameter of 2 mm at the center, and a DC12V fan (diameter 50 mm) attached at a position 1 mm away from the back surface was used. Then, it was cooled by sending air to the back.

  In addition, a porous body of the sample 82 was prepared by forming a through-hole having a diameter of 3 mm in the center of the porous body in which columnar bodies were formed on the front and back surfaces of the sample 81. The sample 82 was cooled by sending air from the back using a DC12V fan (diameter 50 mm) mounted at a position 1 mm away from the back.

  For each of these samples, a cooling experiment was performed in the same manner as in Example 1. As a result, the temperatures measured by embedding an RTD element in an AlN heater were 27 ° C. for sample 80, 28 ° C. for sample 81, and 82 ° for sample 82. It was 27 ° C.

[Example 25]
Using the porous body in the sample 49 of Example 15 above, as shown in FIG. 11, a circular through hole 8a having a diameter of 3 mm reaching the porous body is opened in the center of the Cu plate on the back side, and the width is 1 mm around the periphery. 4 L-shaped through-holes 8b were opened, and the porous body 1 of the sample 83 was produced.

  The porous body 1 was assembled in the same manner as in Example 1 to constitute a cooling system for cooling experiments. As shown in FIG. 12, the central through hole 8a and the outer peripheral four sides were opened to the atmosphere and air was sucked. On the exhaust side, the pressure was reduced from the four L-shaped through holes 8b on the exhaust side by a pump 9 at 5 liters / minute. When the sample 83 was subjected to a cooling experiment in the same manner as in Example 1, the temperature measured by embedding an RTD element in an AlN heater was 29 ° C.

[Example 26]
The porous body of sample 84 was produced by carbon coating the porous body of sample 49 of Example 15. The emissivity of the porous body of Sample 84 was 0.91. When the sample 84 was subjected to a cooling experiment by the same method as in Example 1, the temperature measured by embedding the RTD element in the AlN heater was 29 ° C.

  A porous body of sample 85 was manufactured by applying Ni plating to the porous body of sample 49 of Example 15 to a thickness of 5 μm. When a cooling experiment was performed on the sample 85 by the same method as in Example 1, the temperature measured by embedding an RTD element in the AlN heater was 34 ° C. for the sample 49, whereas that for the sample 85 was 35 ° C. Met.

  The porous body of the sample 49 and the sample 85 was exposed for 100 hours with a high-temperature humidification tester with a temperature of 80 ° C. and a humidity of 80%, and the same evaluation as described above was performed. Sample 85 had no characteristic change at 36 ° C.

It is a schematic sectional drawing which shows one specific example of the cooling member by this invention. It is a schematic sectional drawing which shows one specific example of the porous body in the cooling member of this invention. It is a schematic sectional drawing which shows the other specific example of the porous body in the cooling member of this invention. It is a schematic sectional drawing which shows the specific example of the cooling experiment apparatus using the cooling member of this invention. It is general | schematic sectional drawing which shows the cooling experimental apparatus by a comparative example. It is general | schematic sectional drawing which shows Cu foil which formed one side used as a part of porous body in the Example in uneven | corrugated shape. It is a schematic sectional drawing which shows the columnar body of the shape containing the curve which comprises the porous body of this invention. 1 is a schematic cross-sectional view showing an arch-shaped columnar body constituting a porous body of the present invention. It is general | schematic sectional drawing which shows the columnar body of the shape containing multiple curves which comprise the porous body of this invention. It is a schematic sectional drawing which shows the S-shaped columnar body which comprises the porous body of this invention. 1 is a schematic plan view showing a porous body provided with through holes for air circulation according to the present invention. It is general | schematic sectional drawing which shows the other specific example of the cooling experiment apparatus using the cooling member of this invention.

Explanation of symbols

1 the cooling member 2 be cooled 3 porous body 3a columnar body 3b flange portion 4 substrate 5 AlN heater 6 Al ₂ O ₃ substrate 7 Cu substrate 8 through hole 8a circular through-hole 8b L-shaped through-hole 9 pump 10 the thermal conductivity Seat 11 Al fin 12 Business trip 13 Fan

Claims (28)

  A cooling member that cools in contact with a body to be cooled, and at least a contact surface side with the body to be cooled is formed of a porous body having open pores, and the porous body is elastically deformed and / or plastically deformed to be cooled. A cooling member, wherein the cooling member is in contact with a body and allows a coolant to flow into open pores of the porous body.   The contact area occupied by the portion where the porous body is in contact with the cooled body excluding the open pores is 0.01% or more with respect to the opposing area in the contact state between the cooled body and the porous body. The cooling member according to claim 1, wherein:   The cooling member according to claim 1 or 2, wherein the porosity of the porous body is 50% or more.   The cooling member according to claim 1, wherein the porous body has a thickness of 200 μm or more.   The cooling member according to claim 1, wherein the porous body has a plurality of uneven shapes.   The cooling member according to any one of claims 1 to 5, wherein a plate-like body within the thickness of the porous body is formed in a gap inside the porous body.   The cooling member according to claim 1, wherein an elastic deformation amount and / or a plastic deformation amount of the porous body is 100 μm or more.   The cooling member according to claim 1, wherein the porous body is made of a material having a Young's modulus of 150 GPa or less.   The cooling member according to claim 1, wherein the porous body is made of a material having a thermal conductivity of 100 W / m · K or more.   The cooling member according to claim 1, wherein the porous body contains at least copper or aluminum.   The refrigerant contact area in which the surface of the open pores of the porous body is in contact with the refrigerant is 5 times or more with respect to the opposing area in the contact state between the body to be cooled and the porous body. The cooling member according to any one of 10.   It has a thin intervening layer of 50 micrometers or less which fills up the unevenness | corrugation gap resulting from each surface roughness between the contact surfaces of the said porous body and a to-be-cooled body. The cooling member as described.   The cooling member according to any one of claims 1 to 12, wherein the porous body has a structure in which a large number of columnar bodies are arranged on a substrate of the cooling member.   The cooling member according to claim 13, wherein the columnar body has a diameter of 500 μm or less and an aspect ratio of 5 or more.   The cooling member according to claim 13 or 14, wherein a plurality of branch bodies are formed on a side surface of the columnar body.   The cooling member according to any one of claims 13 to 15, wherein the whole or a part of the columnar body has a structure including a curve.   The cooling member according to any one of claims 13 to 15, wherein the whole or a part of the columnar body has a shape including a plurality of curves, a spiral shape, or an S-shaped structure.   The cooling member according to claim 1, wherein the porous body has a metal porous body structure or a metal honeycomb structure.   The cooling member according to claim 1, wherein the porous body has a structure in which metal wires or carbon fibers are entangled with each other.   The cooling member according to claim 1, wherein the porous body is a resin whose surface is metallized.   The cooling member according to claim 20, wherein the porous body is a porous fluororesin having a metallized surface.   The cooling member according to any one of claims 1 to 21, wherein the cooling member is circulated into the open pores of the porous body by feeding or sucking out the refrigerant.   23. The cooling member according to claim 22, wherein the cooling member is cooled by flowing a refrigerant on the back side of the porous body that is opposite to the contact surface with the object to be cooled.   The cooling member according to claim 22, wherein the cooling member is cooled by flowing a coolant through both the back surface side of the porous body and the porous body, which are opposite to the contact surface with the object to be cooled.   The refrigerant is circulated into the open pores of the porous body by feeding or sucking out the refrigerant from one or a plurality of through holes provided on the back side opposite to the contact surface with the object to be cooled. Item 23. The cooling member according to Item 22.   126. The cooling member according to claim 125, wherein the refrigerant is air.   127. The cooling member according to any one of claims 126, wherein the emissivity of the surface of the porous body is 0.5 or more. An electronic device such as a television, a projector, or a personal computer, comprising the cooling member according to any one of claims 1 to 27.

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