JP5419000B2 - Cryogenic microslash ultra high heat flow cooling system - Google Patents

Description

  The present invention relates to a cryogenic microslash ultra-high heat flow rate electronic cooling system and an electronic device cooling method.

The local heat flow rate (heat flux) generated in next-generation semiconductor components and computer chips exceeds 10 ⁶ W / m ² , the total power reaches 300 W, and it is about to exceed the heat generation density of the reactor core. There are currently no cooling devices that can effectively manage the heat generated at this level. In the future, the semiconductor design rules will become finer, so it is expected that the CPU will consume less power. On the other hand, the heat generation density will be higher than before, so in the near future it will reach a heat generation density similar to that of a nuclear fusion reactor. Even predicted. In particular, next-generation semiconductor components such as next-generation high-performance CPUs and computer chips consume more power than conventional semiconductor components such as CPUs and semiconductor devices such as LSIs, and the heat flow rate is 10 ⁶ W / m ² . If it does not have the heat dissipation performance, it is predicted that the predetermined performance cannot be exhibited, and even if the current liquid cooling method and forced convection boiling heat transfer are used, the level can no longer be followed. For these reasons, it is desired to develop a new processor cooling method that is most important for realizing high speed, high density, and high reliability of the system.

In addition, the next-generation processor not only generates a large amount of heat, but it is also expected that the heat density will be non-uniform due to the nano-order wiring and multiple “hot spots” will appear on the processor [Singhal, V and Garimella, SV, "A Novel Valveless Micropump With Electrohydrodynamic Enhancement for High Heat Flux Cooling", IEEE Trans. on Advanced Packaging, Vol.28, No.2 (2005), pp. 216-230 ]. This hot spot is particularly computationally intensive and needs to be kept below a certain temperature in the cooling system, but it is a "passive" such as a conventional heat sink, fan cooler, heat pipe, etc.
In addition, the method of absorbing and dissipating heat requires a large metal material and has the disadvantage that the hot spot cannot be cooled effectively.

As a typical research on the liquid cooling of the processor, there is a technique “Micro-Fluidic Cooling” for cooling an LSI die or package with a liquid (Non-patent Document 1). This liquid cooling system is characterized in that it has an “electrokinetic pump” that circulates the coolant. However, the idea of imparting functionality to the refrigerant itself has not yet been reached, and it cannot be said that it is for PC level cooling and has high heat flow rate cooling performance.

Slush hydrogen is an equilibrium mixture that contains liquid hydrogen and solid hydrogen, and exists on the solid-liquid boundary of hydrogen. When hydrogen is used as a fuel in space, it is simply in a liquid state. Compared with hydrogen, various advantages have been recognized and attention has been paid, and development of its production technology and storage technology has been conducted. However, it is a technology that requires a lower temperature than liquid hydrogen, and it is still a developing technology because it deals with two-phase substances with different properties such as a solid-liquid state. Similarly, slush nitrogen is a cryogenic liquid consisting of a solid-liquid two phase containing solid nitrogen particles in liquid nitrogen. Its application is expected as a next-generation refrigerant for distance superconducting cables. As a technology for producing a slush two-phase liquid such as slush nitrogen, WO 2004/080892 (International publication date: September 23, 2004, Patent Document 1), Japanese Patent Application No. 2006-170710
(Patent document 2) etc. are mentioned.

WO 2004/080892 (International publication date: September 23, 2004) Japanese Patent Application 2006-170710 (Application date: July 4, 2006) Singhal, V. and Garimella, S. V., "A Novel Valveless Micropump With Electrohydrodynamic Enhancement for High Heat Flux Cooling", IEEE Trans. On Advanced Packaging, Vol.28, No.2 (2005), pp. 216-230

In semiconductor components such as next-generation semiconductor elements and computer chips, it is a big problem to solve the problem of heat generation due to the operation. For next-generation CPUs, it is a challenge to achieve ultra-high heat flow cooling. In addition, the next-generation processor not only generates a large amount of heat, but it is also expected that, due to the nano-order wiring, the heat generation density will be uneven and multiple hot spots will appear on the processor. Development of cooling technology is required.

An object of the present invention is to provide a new electronic cooling system having a cooling performance of an ultra-high heat flow rate of 10 ⁶ W / m ² which is considered to occur in next-generation semiconductor components and computer chips.
As a result of earnestly researching the development of an ultra-high heat flow rate electronic cooling system applied to next-generation semiconductor components such as next-generation high-performance CPUs and computer chips, the inventor has developed a cryogenic microslash two-phase flow as a functional refrigerant. As a cooling method by forced convection heat transfer of micro slush spray flow, a synergistic effect by melting latent heat of slush particles is also added, and cooling method by forced convection boiling heat transfer (10 ⁵ W / m ² order) of water is used We found that it is possible to create ultra-high heat flow mixed-phase cooling that achieves heat transfer characteristics and cooling characteristics several tens of times (10 ⁶ orders) than the case, and next-generation cryogenic microslash two-phase refrigerant type ultra-high heat flow electrons It came to provide a cooling system.

Thus, the present invention provides the following.
[1] A cooling method for electronic equipment using a cryogenic microslash solid-liquid two-phase fluid, in which a spray flow of a cryogenic microslash solid-liquid two-phase fluid formed and ejected by a microslash- generating atomizing nozzle An electronic device cooling method characterized in that heat transfer is performed by colliding with an electronic device heating element at high speed.
[2] The method for cooling an electronic device according to the above [1], wherein the spray flow is microslush nitrogen.
[ 3 ] The above [1] or [ 3 ], wherein the electronic device is selected from the group consisting of semiconductor components, semiconductor elements such as IC and LSI, computer chips, and microprocessors including CPUs and GPUs [2] The method for cooling an electronic device according to [2].
[4] Any one of [1] to [3] above, wherein the latent heat of fusion of the cryogenic microslash particles in the spray flow is used for heat transfer from an electronic device heating element. Cooling method for electronic equipment.

The present invention provides a cooling method for electronic equipment such as a CPU by forced convection heat transfer of a microslush nitrogen two-phase spray flow, and in this cooling method, a synergistic effect by slush melting latent heat is also added, and the best cooling at present. It is possible to construct a system that can obtain heat transfer characteristics and cooling characteristics several tens of times higher than the cooling method using forced convection boiling heat transfer. In the present invention, it is possible to construct an ultra-compact spray cooling unit for a large supercomputer.
Other objects, features, excellence and aspects of the present invention will be apparent to those skilled in the art from the following description. However, it is understood that the description of the present specification, including the following description and the description of specific examples and the like, show preferred embodiments of the present invention and are presented only for explanation. I want. Various changes and / or modifications (or modifications) within the spirit and scope of the present invention disclosed herein will occur to those skilled in the art based on the following description and knowledge from other parts of the present specification. Will be readily apparent. All patent documents and references cited herein are cited for illustrative purposes and are not to be construed as a part of this specification. is there.

The present invention provides an ultra-high heat flow rate electronic cooling system utilizing a microslash two-phase flow. In the present invention, a new ultra-high heat flow rate cooling system has been developed that can realize a cooling heat flow rate exceeding 10 ⁵ (W / m ² ), which could not be achieved in the past, with regard to cooling of the heating base.
In the present invention, high-speed spray flow of micro / nano slash composed of micro solid particles newly generated from liquefied gas as a refrigerant enabling ultra high heat flow rate cooling, and liquefaction that is a solid-liquid two-phase fluid having high functionality A cryogenic microslash two-phase flow of gas is used. In a particularly preferred embodiment, in the present invention, a micro-nano slash high-speed spray flow composed of micro solid nitrogen particles newly as a refrigerant enabling ultra high heat flow rate cooling, and a micro-nano slash-liquid nitrogen solid-liquid two-phase Use flow. This super-high heat flow rate electronic cooling system may refer to the one that utilizes the high cold holding amount (enthalpy) of the slash and the ultra-high-speed spray flow. The ultra-high heat flow rate electronic cooling system includes a heat transfer characteristic improved to an order of several tens of times the critical heat flow rate in forced convection boiling heat transfer of water, which is the cooling method having the highest performance at present. Good. The ultra-high heat flow rate electronic cooling system includes a system in which contact thermal resistance at the package joint is greatly reduced. The cooling method of the present invention does not focus on improving only the peripheral equipment for PC cooling, but uses a cooling method by active cooling of a spray type and a two-phase liquid cooling system that gives the refrigerant itself high functionality. Therefore, we offer a high-performance next-generation processor cooling system that can be cooled at ultra-high heat flow rates and can be applied to large-scale computing systems such as supercomputers.

  As used herein, “slash” or “slash particle” refers to solid particles such as solid nitrogen, solid oxygen, and solid hydrogen obtained by freezing liquefied gas such as liquid nitrogen, liquid oxygen, and liquid hydrogen. It refers to a system that is suspended or dispersed in a liquefied gas such as liquid nitrogen, liquid oxygen, or liquid hydrogen, or such a system. In the present invention, nitrogen slush (or nitrogen slash particles) is preferable, and nitrogen microslash is particularly preferable. And when it is called “microslash” or “microslash particle”, the particle size, that is, the size of the diameter of the solid particle, refers to a relatively small one, as described for microslash nitrogen below. In this case, it may mean that the average particle size of the particles is 1.0 mm or less, and further 0.5 or less or 0.2 mm or less. In the present invention, preferred is a microslash particle of nitrogen. Particularly preferred are those in which the size of solid particles shows a uniform distribution.

In the present specification, “microslash nitrogen” is an equilibrium mixture that contains liquid nitrogen and solid nitrogen, and exists on the solid-liquid boundary line of nitrogen. Mean particles and those containing relatively uniform particles. Here, “fine” and / or “uniform” particles refer to electronic devices such as next-generation semiconductor components, ICs, and LSIs.
Such as semiconductor devices such as semiconductor chips, microprocessors such as CPUs, GPUs, etc. that show high heat generation density and / or hot spot generation, refers to those that can be effectively cooled effectively The term “substantially practicable” may mean that it can be used over a long period of time, or to the extent that a person skilled in the art deems practically satisfactory.

The microslash nitrogen is a cryogenic liquid composed of a solid-liquid two-phase containing solid nitrogen particles in liquid nitrogen, and what is present as solid nitrogen is at least an average particle diameter of 2 to Those having a size smaller than 5 mm, for example, solid nitrogen particles or crystalline nitrogen particles having an average particle size of 1.5 mm or less, or 1.3 mm or less, preferably 1.0 mm or less, more preferably Is 0.8 mm or less or 0.6 mm or less, further 0.5 mm or less or 0.3 mm or less, and typically 0.2 mm or less, further 0.1 mm or less, or a micron order size. In a more preferred embodiment, what is present as solid nitrogen may be at least an average particle size smaller than 1 to 100 μm. For example, the average particle size of solid nitrogen particles or crystalline nitrogen particles is One that is 50 μm or less, or 10 μm or less, preferably 1.0 μm or less, more preferably 800 nm or less or 500 nm or less, further 100 nm or less or 50 nm or less,
Further, those having a size of 10 nm or less and a nanometer order are mentioned.
In one embodiment of the present invention, the liquid mixture containing the particulate solid nitrogen (or crystalline nitrogen) has a particle volume fraction of 0.05 to 0.3. In some cases, the particle volume fraction is 0.08.
In the preferred case, the particle volume fraction is 0.1 to 0.26, more preferably 0.125 to 0.25, and in certain cases the particle volume fraction is 0.15 to 0.25. It is what is.

As a method for producing the microslash nitrogen used in the technology of the present invention, a liquid nitrogen flow or a supercooled liquid nitrogen flow (supercooled liquid nitrogen flow) is atomized by the action of a cryogenic helium gas flow. This can be done by subjecting it to atomization-cooling. The microslash fluid generation method is capable of generating a slush solid-liquid two-phase fluid (particularly, a microslash solid-liquid two-phase fluid) of a liquefied gas, In the vicinity, a gas or liquid flow at a temperature similar to or lower than the temperature of the cryogenic liquid is introduced in the same or almost the same direction as the flow of the cryogenic liquid, and the gas collides with the liquid. It is carried out by forming fine particles, or by causing liquids having different properties to collide with each other to form fine particles. The gas or liquid stream introduced is introduced at high pressure and / or high speed, and is generally introduced under high pressure and high speed conditions. The flow to be introduced is an ejected flow or a jet flow at the outlet, and has the effect of atomizing the liquid (may be an atomized jet flow or an atomized jet flow). As long as the desired atomization purpose can be achieved, any pressure can be adopted as the high pressure, and it is determined appropriately depending on the diameter of the outlet (jet outlet) to be injected. In some cases, it can be 10 to 1,000 atmospheres, and in other cases, it can be 10 to 100 atmospheres or 10 to 50 atmospheres. In addition, the high pressure may be a pressure that can achieve a required ejection flow rate from the ejection port. The high speed may refer to an ejection flow velocity from the ejection port, for example, 5 to 850 m / s, in some cases 8 to 540 m / s, and in other cases 10 to 250 m / s. Or 12-100 m / s, 13-50 m / s or 14
˜25 m / s.

The liquefied gas may typically refer to a substance having a melting point of −190 ° C. or lower at normal pressure, and examples thereof include liquid nitrogen, liquid oxygen, liquid hydrogen, and liquid argon. Often, liquid nitrogen is preferred. The case where the liquefied gas is nitrogen will be described below. For example, when the microslush nitrogen is ejected from a nozzle or a stream of liquid nitrogen or a supercooled liquid nitrogen stream, the microcooled nitrogen and the supercooled liquid nitrogen stream are located approximately at or near the center of the supercooled liquid nitrogen stream. This can be realized by introducing a gas or liquid flow (a cryogenic introduction flow or a cryogenic injection auxiliary flow) having a temperature equal to or lower than the temperature of the supercooled liquid nitrogen in the same direction or substantially the same direction. In one embodiment of the present invention, the cryogenic introduction stream may have a melting point or boiling point lower than the melting point of nitrogen -209.86 ° C, for example, hydrogen has a melting point of -259.14 ° C, a boiling point of -252.87 ° C, Helium (He) has a melting point of −272.2 ° C. and a boiling point of −268.9 ° C. and can be used. In particular, helium is preferable because it can flow a cryogenic helium gas and is inert.

Using a slush nitrogen two-phase flow (especially including a micro-slash nitrogen two-phase flow and even a nano-slash nitrogen two-phase flow), a high-speed spray flow of micro slush composed of fine solid nitrogen particles is formed to generate heat. For example, in order to increase the transmission efficiency (cooling capacity) and significantly reduce the contact thermal resistance at the semiconductor element package junction, for example, a slash particle generation atomization nozzle, that is, a particle diameter that is as small and uniform as possible. A slush atomizing nozzle that can generate slush particles in a short time and efficiently is advantageous, such as a nozzle using a high-speed or jet flow of cryogenic helium gas, that is, a two-fluid ejector nozzle. It is valid. The two-fluid ejector nozzle injects cryogenic helium gas cooled by a helium refrigerator into the ejector at high pressure and high speed, whereby supercooled liquid nitrogen in the stirring vessel is sucked into the ejector, and high-speed flow of helium gas. That have a mechanism that forms fine slush nitrogen particles by collision and mixing and ejects them outside the ejector nozzle (or a mechanism that jets them). Those that use such mechanisms are used in the present invention. It may be possible. A typical example is a concentric mixed high-speed two-fluid nozzle capable of flowing liquid nitrogen and cryogenic helium gas. The nozzle is described in, for example, WO 2004/080892 (International Publication Date: September 23, 2004, Patent Document 1), Japanese Patent Application No. 2006-170710 (Patent Document 2), and the like. In the concentric mixing type high-speed two-fluid nozzle, liquid nitrogen is sucked into the ejector surrounded by the wall through the line by the flow of helium gas ejected from the jet outlet at high speed and high pressure, and the high-speed helium gas flow It collides and is atomized, and slush nitrogen particles are formed from the ejector outlet of the ejector, which is supplied into liquid nitrogen (or liquid nitrogen stream) and mixed.

In one preferred embodiment, a microslash nitrogen two-phase fluid is generated using a spiral nozzle. This spiral type nozzle is described in Japanese Patent Application No. 2006-170710 (Patent Document 2). The spiral nozzle can efficiently produce microslash nitrogen particles having a uniform particle diameter. The two-fluid spiral ejector nozzle uses a high-speed flow of a cryogenic helium gas. For example, a cryogenic helium gas cooled by a helium refrigerator is injected into the ejector at a high pressure and at a high speed. Supercooled liquid nitrogen is sucked into the ejector and forms microslash nitrogen particles by collision and mixing with a high-speed flow of helium gas, and when passing through the spiral nozzle part, atomization to the micro-order particle size is promoted and the nozzle It has a mechanism to be ejected to the outside. Those utilizing such a mechanism may be included in the present invention. As a method for producing microslashes, it is possible to continuously produce microslashes by using a spiral type nozzle having no mechanical rotating part, which functions as a high performance atomizing nozzle and is excellent.

In a typical case, the diameter of the jet outlet of the high-speed flow of the cryogenic helium gas and the diameter of the outlet (injection outlet) of the atomized slash particles may be the same or approximately the same, and Depending on the pressure to be applied and the flow rate of the target helium gas, it can be appropriately determined, for example, 0.05 to 5.0 mm, in some cases 0.1 to 3.0 mm, in other cases 0.2 to 3.0 mm or 0.3 to It can be set to 2.0 mm, 0.4 to 1.5 mm, or 0.5 to 1.2 mm.
In the present invention, the spiral type nozzle is further improved, and an ultrasonic transducer mounting type part spiral type nozzle that can make particles generated by the nozzle more uniform and finer is preferably used. it can. An example of a typical ultrasonic transducer mounting type part spiral type nozzle is shown in FIG. In the ultrasonic vibrator mounting type part spiral type nozzle, the ultrasonic vibrator is installed at the jet nozzle part of the ejector nozzle, and the fine and fine slush nitrogen particles are produced by the synergistic effect of ultrasonic atomization promoting action and ultrasonic cavitation. The microslash having excellent properties can be obtained by the mechanism that the atomization to the micro order particle diameter is promoted when passing through the spiral nozzle portion and the particles are ejected to the outside of the nozzle.
Thus, the present invention provides a micro slash generation nozzle utilizing ultrasonic cavitation. This nozzle eliminates a mechanical rotating part as much as possible, and can continuously generate particles at extremely low temperatures.

The micro slash generation device (including the micro slash nitrogen generation device) has a structure in which a liquid and a gas collide to generate fine particles (micro particles), and is supplied by, for example, a liquid nitrogen supply line A nozzle (a cryogenic helium gas injection port) that injects (or jets) a cryogenic helium gas is disposed at a substantially central position in the flow of liquid nitrogen, and is injected from the cryogenic helium gas injection port. The liquid nitrogen is sucked from the liquid nitrogen supply line by the helium gas flow, and the liquid nitrogen flow that flows along the periphery of the cryogenic helium gas flow has, for example, a funnel having a cross-sectional shape. Flow toward the narrow part (cylinder opening) of the mold (roof type), collide with the cryogenic helium gas flow, and form fine particles in the form of mist Ri, and thus to generate a micro-slush fine particles such as micro slush nitrogen is emitted from the snout of the cross-sectional shape funnel portion. An ultrasonic vibrator is provided at or near the tube opening, and finer and more uniform fine particles are formed by cavitation using ultrasonic waves.
When ultrasonic waves are applied to a liquid or solution, bubbles are generated due to local pressure fluctuations. Bubbles generated by ultrasonic waves concentrate in a short time during the adiabatic compression process.
It is thought to form a local field. That is, cavitation occurs when a liquid or solution is irradiated with ultrasonic waves. Cavitation is a physical phenomenon in which bubbles are generated and disappeared in a short time due to a pressure difference in a liquid flow. When bubbles collapse due to cavitation, it is known that a short-lived high-temperature, high-pressure local field (hot spot) is formed. By using this, the generated particles can be micronized. is there.

  The micro slash generator includes an ejector nozzle that enables generation of micro slash such as micro slash nitrogen, and the ejector nozzle has a liquid nitrogen supply line for the flow of liquid nitrogen flowing through the ejector. An outlet that has a cryogenic helium gas injection port disposed substantially at or near the center, and in which a mixture of liquid and gas is injected in the direction of flow of the gas flow injected from the helium gas injection port (Preferably, the cross-sectional shape has a funnel-shaped narrow opening). The microslash generator may operate intermittently to generate solid nitrogen particles, or may generate solid nitrogen particles continuously for a certain period of time. In a preferred case, the ejector nozzle is equipped with a heating device, and should be able to remove any clogging due to solid nitrogen particles or adhesion to the nozzle. In a more preferred example, the ejector nozzle may be a state in which the discharge port is a spiral nozzle and protrudes from the circulating liquid. The ejector nozzle having the spiral-shaped discharge port causes moderate turbulence by passing a high-speed jet flow through the spiral portion, contributing to more fine pulverization, and prevents the generated microslash from adhering to the nozzle. Preventing the formation of continuous microslashes.

For the microslash atomization process and particle size distribution, a two-color laser PIA optical measurement system is used to analyze the particle image, for example, particle size distribution and number density distribution measurement by direct imaging method (Direct-Imaging Techniques). Can be analyzed by the two-dimensional visualization image measurement. In the two-color laser PIA optical measurement system, a two-color laser, for example, a dual-pulse YAG laser, a dye laser for depth of field check, a high-resolution color camera for PIA, and PIA image analysis software can be used. In addition, it is preferable to use a high-load distributed computing (Grid Computing) technique based on massively parallel computation using a cluster type high-speed workstation for analysis such as numerical analysis, and the atomization characteristics of the nozzle, for example, the particle size distribution The number density distribution, flow velocity / temperature distribution, etc. can be appropriately and quantitatively evaluated. It is possible to analyze by combining the atomized two-phase heat transfer numerical calculation and PIA measurement using LES-VOF method.

In the present invention, a processor ultra-high heat flow rate spray cooling method using solid nitrogen (or solid hydrogen) microslash two-phase flow having a micro particle size is provided. In the present invention, there is provided a microchannel super high heat flow liquid cooling method using a microslash two-phase flow in which microslush nitrogen and / or solid hydrogen particles are suspended as a refrigerant. In this cooling method, the micro slash actively detects a hot spot and enables uniform cooling. The ultra-high heat flow rate electronic cooling system of the present invention is a system that exhibits optimum mixed-phase cooling performance.
Slush nitrogen (temperature 63K), which is lower in temperature than liquid nitrogen (temperature 77K), is used as a refrigerant to show improved cooling capacity. Furthermore, for slush nitrogen with a solid mass fraction of 50%, the density increases by 16% and the cold retention (enthalpy) increases by 22%, so forced slush nitrogen two-phase spray flow and / or slush nitrogen solid-liquid two-phase flow It is a cooling method using convective heat transfer, and is a technology with a synergistic effect due to latent heat of slush melting.

Microslash direct spray cooling uses high-velocity impact of microslash particles, including the intrusion of slush into the micron-order package joint gap, and synergistic use of forced convection and latent heat of fusion. This is a technology for heat transfer. This is a technique for greatly reducing the contact thermal resistance at the joint. The micro-slash active two-phase liquid cooling system uses the latent heat of fusion of slush nitrogen, and is a technique that achieves a liquid cooling effect with higher efficiency than when using a supercooled liquid nitrogen single-phase flow. In this system, the micro slash actively detects a hot spot, and achieves relatively uniform cooling over a heating element (heating source) in which nonuniformity exists. In the present invention, the contact heat resistance of the cooling part can be greatly reduced by using the microchannel, and this is also a technique that utilizes the synergistic effect of the two-phase cooling and the microcooling. For the microchannel, those known in the art can be used. For example, Singhal, V. and Garimella, SV, "A Novel Valveless Micropump With Electrohydrodynamic Enhancement for High Heat Flux
Cooling ", IEEE Trans. On Advanced Packaging, Vol. 28, No. 2 (2005), pp. 216-230 (Non-Patent Document 1), and the like, or modified structures thereof.

  The present invention provides a cooling device for an electronic device heating element. The present invention also provides a cryogenic microslash ultra high heat flow rate electronic cooling system. In a typical case, the cooling device for an electronic device heating element includes a cooling module for bringing a liquid refrigerant that cools each heating element into contact with the heating element to transfer heat, and a liquid refrigerant that supplies the liquid refrigerant to the heating element. A supply circuit and a liquid refrigerant driving means that operates to circulate the liquid refrigerant through the liquid refrigerant supply circuit are provided. In the cooling device, the liquid refrigerant is a microslash solid-liquid two-phase fluid of liquefied gas, and the cooling device is provided with a microslash generation system including a cryogenic microslash atomization nozzle. The cryogenic micro slash atomization nozzle preferably includes a spiral nozzle. In a more preferred embodiment, the cryogenic microslash atomization nozzle has an ultrasonic vibrator installed at the nozzle outlet. The cooling module may have a package joint gap of the electronic device heating element, or may have a microchannel adjacent to the heating unit of the electronic device heating element. In general, heat transfer is performed by flowing a cryogenic microslash solid-liquid two-phase fluid through the microchannel adjacent to the package joint gap of the electronic device heating element or the heating portion of the electronic device heating element. This cryogenic microslash ultra-high heat flow electronic cooling system uses the principle of cooling an electronic device heating element using a cryogenic microslash solid-liquid two-phase fluid of liquefied gas as a refrigerant. May all be included. Typically, the liquefied gas cryogenic microslash solid-liquid two-phase fluid of the system includes microslush nitrogen.

The cooling module may be configured so that the microslash spray flow can directly collide with the heat generating portion of the electronic device heating element at high speed, and / or, for example, one or the base of the silicon wafer on which the LSI is built or A configuration in which a plurality (usually a plurality) of microchannels (microchannels) is provided is also included. The cooling module is preferably designed so that the contact thermal resistance generated between the package solid surfaces of a processor such as a CPU is reduced as much as possible. The design includes those made by applying analysis methods known in the art.

  The liquid refrigerant supply circuit usually includes a conduit and the like, and preferably, a heat insulating conduit, a flexible conduit, a corrugated tube or the like that is durable at a cryogenic temperature can be used. The circuit is connected at least to the refrigerant inlet of the cooling module and also connected to the refrigerant outlet of the cooling module so that in a typical case a closed circuit can be formed. In the liquid refrigerant supply circuit, microslash particles generated by the microslash generation system, for example, solid nitrogen fine particles are supplied to the liquid refrigerant. The micro slash generation system may be provided in the liquid refrigerant supply circuit, or may be provided in a side conduit portion through a conduit or the like. The microslash generation system can also be arranged so that the microslash spray stream can be directly impinged on the cooling module at high speed. One or more microslash generation systems can be arranged in the system.

The liquid refrigerant driving means functions to circulate the liquid refrigerant through the liquid refrigerant supply circuit, and examples thereof include a pump and an actuator. In a typical case, the pump is preferably one with as little pulsation as possible, for example, what is known as a micropump may be used. For example, Singhal, V. and Garimella, SV, "A Novel"
Valveless Micropump With Electrohydrodynamic Enhancement for High Heat Flux Cooling ", IEEE Trans. On Advanced Packaging, Vol.28, No.2 (2005), pp. 216-230 (Non-patent Document 1) As the liquid refrigerant driving means, the micro slush generation system can generate a high-speed micro slash spray flow, and therefore, the liquid slash driving system may utilize the micro slash generation system.

In addition to the configuration described above, the electronic device heating device cooling device and the cryogenic microslash super high heat flow electronic cooling system of the present invention include a cooling device and a pressurizing device for generating a microslash in the microslash generation system. In addition, a tank for storing a refrigerant, a facility such as a piping system, a device, a machine, and the like may be appropriately and arbitrarily provided. Also, sensors, control devices, control pumps, flow meters, etc. can be installed to monitor and control the operating status of the device, and data and signals collected with the computer can be exchanged It may be. The cooling system is preferably capable of computer control. FIG. 13 schematically shows an apparatus for an ultra-high heat flow rate electronic cooling system using the microslush spray flow and the two-phase liquid cooling method of the present invention.
In the present invention, by adopting a cooling method by forced convection heat transfer of a microslash nitrogen two-phase spray flow, a synergistic effect due to latent heat of fusion of slush particles is also added, and forced convection boiling heat transfer of water having the highest cooling capacity at present. It is considered that heat transfer characteristics and cooling characteristics several tens of times (10 ⁶ W / m ² order) can be obtained compared to the case of using the cooling method (10 ⁵ W / m ² order).
Microslash direct spray cooling uses high-velocity impact of microslash particles, allowing slashes to enter micron-order package joint gaps and realizing heat transfer by the synergistic effect of forced convection and latent heat of fusion. It has novelty and superiority in that it can greatly reduce the contact thermal resistance.
The present invention will be described in detail with reference to the following examples, which are provided merely for the purpose of illustrating the present invention and for reference to specific embodiments thereof. These exemplifications are for explaining specific specific embodiments of the present invention, but are not intended to limit or limit the scope of the invention disclosed in the present application. In the present invention, it should be understood that various embodiments based on the idea of the present specification are possible.
All examples were performed or can be performed using standard techniques, except as otherwise described in detail, and are well known and routine to those skilled in the art. .

[Generation of microslush nitrogen solid-liquid two-phase spray flow by atomization nozzle]
FIG. 1 shows a spiral type nozzle. The spiral type nozzle uses a high-speed flow of cryogenic helium gas. By injecting cryogenic helium gas cooled by a helium refrigerator into the ejector at high pressure and high speed, the supercooled liquid nitrogen in the stirring vessel is Slush nitrogen particles are formed by being sucked into the ejector and colliding with a high-speed flow of helium gas. When passing through the spiral nozzle, atomization to the micro-order particle size is promoted and ejected outside the nozzle. . It is possible to generate slush nitrogen particles having a uniform particle size. A photograph of an adiabatic two-fluid spiral type nozzle for generating a microslash spray flow used in the experiment is shown in FIG.

The particle size distribution of the particles formed by the microslash nitrogen generation nozzle was analyzed by particle imaging velocimetry (PIV). The particle size distribution (statistics) was calculated by image processing. The slash particle size distribution is fed back to CFD (Computational Fluid Dynamics) calculation conditions as a statistic rather than an absolute value.
When microslash nitrogen was formed under the following conditions using the spiral type nozzle of FIG. 2, it was confirmed that the following particles were obtained. The state of the micro slash spray from the nozzle is shown in FIG.

Conditions for microslash generation system:
[Helium] Gauge pressure (MPa)
Pressure of liquid helium tank: Pressure (GHe) 0.157
Nozzle pressure (GHe) 0.107
[Liquid nitrogen] Gauge pressure (MPa)
Pressure amount of supercooled liquid nitrogen tank: Pressure (N ₂ ) 0.18
[Slash particles] m / s
Average spray velocity 14
As an example of the obtained results, the particle size distribution (statistics) of the generated microslash nitrogen particles was as shown in FIG. Most of the produced slush nitrogen particles had a particle size of 0.2 mm or less.

[Microslash-based ultra-high heat flow rate solid-liquid two-phase cooling test]
FIG. 5 shows a schematic diagram of a microslash ultra high heat flow rate spray cooling experiment. A micro slash ultra high heat flow rate experimental device was created and the heat flow rate was measured. FIG. 6 shows a piping system of the micro slash ultra high heat flow rate experimental apparatus in this cooling experiment. In FIG. 6, the cooled and cool liquid nitrogen is supplied from the liquid nitrogen tank (11) through the liquid nitrogen conduit (13) to the microslash nitrogen generation nozzle (1). On the other hand, the supercooled cryogenic helium gas is supplied from the liquid helium tank (12) to the microslash nitrogen generation nozzle (1) through the liquid helium conduit (14). The amount of helium gas injected into the nozzle can be adjusted by an inlet valve (15).
A non-uniform superheat base that can generate hot spots to simulate next-generation processors was designed and manufactured. In FIG. 6, the heat flow rate sensor unit (5) is arranged at a position where a high-speed spray flow coming out of the microslash nitrogen generation nozzle (1) is hit, and the heat flow rate sensor unit (5) is moved by a stepping motor (10). It is possible to change the distance of the nozzle (1) from the nozzle through the square screw (8). The heat flow rate sensor unit (5) is arranged inside a vertical visualization container (6) to which a four-sided acrylic plate (7) is attached, and is visually observable. A nitrogen gas outlet (9) is provided at the place, and the entire container (6) is loaded on a gantry (16) with casters so that it can move freely. FIG. 6A shows a state in which the thermal flow rate sensor unit (5) is viewed from the microslash nitrogen generation nozzle (1) side, and includes a heat insulating plate (21) and a heater (2). It is shown. FIG. 7 shows a portion of the vertical visualization container (6) and the gantry (16) on which it is loaded in FIG. FIG. 8 shows a photograph of the appearance of the experimental device (vertical visualization container (6) and the stage (16) on which it is loaded) in this cooling experiment.
FIG. 9 shows a side view of the heat flow rate sensor unit (5), and FIG. 10 shows the heat flow rate sensor unit (5) viewed from the microslash nitrogen generation nozzle (1) side. . In FIG. 9, a ceramic heater (2) is placed on a heat insulating plate (21), and a heater lead wire (4) is connected to the heater (2). ) Is a heat generating part. Further, the heater section (2) is fixed by the press plate (3) so as not to move even when it hits the high-speed spray flow. FIG. 11 shows a photograph of the appearance of the heat flow sensor for measuring the microslash ultra-high heat flow rate and the experimental apparatus mounting portion of the processor simulation base, that is, a photograph of the heat flow sensor unit (5).
An experiment was conducted in which a high-speed spray flow of a microslash solid-liquid two-phase fluid generated by a spiral type ultra-high heat flow rate nozzle was collided with the base, and the ultra-high heat flow rate heat transfer characteristics and cooling characteristics of the microslash spray flow were measured. The measurement was performed with a liquid nitrogen spray flow and a microslash nitrogen (solid-liquid two-phase fluid) spray flow. The heat transfer characteristics due to microslash forced convection and latent heat of fusion at the package joint were measured in detail. Since the package joint is a minute space, a high-precision micro thermocouple was built in the joint and the base, and a high-precision measurement of the heat flow rate in the minute space joint was performed. Regarding the measurement of the temperature field, thermography was used in combination.

FIG. 12 shows the results of measuring the cooling heat flow rate on the heating plate using an ultra-high heat flow rate electronic cooling system. In FIG. 12, the vertical axis represents the heat flow rate, the horizontal axis represents the spraying time, the solid line represents the measurement result regarding the heat flow rate q when the microslash spray flow is used, and the broken line represents the liquid flow rate when only the liquid nitrogen spray flow is used. . When using a microslash spray, a super high heat flow rate of 10 ⁵ W / m ² is achieved with a spray time as short as 4 seconds from the start of spraying, which has a cooling heat flow rate more than twice that of liquid nitrogen spray. Therefore, it can be seen that the cooling performance is very high. In contrast, the spray flow with only liquid nitrogen has a limit of 10 ⁴ W / m ² , and it can be seen that breakthrough with ultra-high heat flow cannot be expected with liquid nitrogen alone.
Regarding microslash spray flow, we investigated the amount of wall heat transfer by direct contact, forced convection heat transfer by high-speed collision, and heat transfer amount based on latent heat of fusion, and investigation on ultra-high heat flow rate heat transfer characteristics based on the latent heat of fusion of microslash. And numerical predictions on the effect of particle size and particle phase volume fraction on microslash spray cooling and analysis to establish an optimal particle size distribution control method that enables ultra-high heat flow rate heat transfer It is.

The cooling technology for electronic devices such as semiconductor elements such as LSIs using the microslash solid-liquid two-phase fluid of the present invention (including a cryogenic microslash ultra-high heat flow electronic cooling system and a microslash two-phase flow cooling electronic device) It is possible to effectively cool semiconductor elements such as semiconductor components, ICs, LSIs, etc., microprocessors such as computer chips, CPUs, GPUs, etc., which require the next generation of ultra-high heat flow cooling, and even hot spots are efficient Can be cooled. Therefore, it solves the cooling mechanism development problem essential for the next generation computer. With this cooling technology, it is possible to realize higher speed, higher density and higher reliability of the next generation computer system.
It will be apparent that the invention may be practiced otherwise than as particularly described in the foregoing description and examples. Many modifications and variations of the present invention are possible in light of the above teachings, and thus are within the scope of the claims appended hereto.

FIG. 2 is a schematic cross-sectional view of a spiral ejector nozzle suitable for generating a microslash solid-liquid two-phase fluid used in the present invention, equipped with an ultrasonic vibrator, and using an ultrasonic cavitation type microslash super high heat flow atomization nozzle It is. It is a drawing substitute photograph which shows the spiral type | mold microslash nitrogen production | generation atomization nozzle utilized by this invention. This figure also shows the spiral nozzle used in the microslash-utilizing super high heat flow rate solid-liquid two-phase cooling test of Example 1 and the nozzle mounting part of the micro-shrush generator. It is a drawing substitute photograph which shows a mode that a micro slash spray flow is inject | emitted from the spiral type micro slash nitrogen production | generation atomization nozzle utilized by this invention. This micro slash spray flow was used in the micro slush utilization type super high heat flow rate solid-liquid two-phase cooling test of Example 1. The result of analyzing the particle size distribution (statistics) of nitrogen microslash particles obtained by generating microslash nitrogen under the conditions shown in Example 1 using a spiral type microslash nitrogen generation atomizing nozzle is shown. . The particle size distribution was analyzed by the PIV method. A state of a micro slash super high heat flow spray cooling experiment using a heating base simulating a next generation processor is schematically shown. The micro slash super high heat flow rate experimental apparatus used in the micro slash utilization type | mold super high heat flow rate solid-liquid two-phase cooling test of Example 1 is shown. The vertical visualization container in the experimental apparatus of FIG. 6 and the part of the gantry on which it is loaded are shown enlarged. It is a drawing substitute photograph which shows the external appearance of the experimental apparatus [the vertical visualization container and the frame part which has loaded it] in the cooling experiment of Example 1. . The side view of the heat flow rate sensor unit part of the experimental apparatus in the cooling experiment of Example 1 is shown. The heat flow rate sensor unit part seen from the micro slash nitrogen production | generation nozzle (1) side of the experimental apparatus in the cooling experiment of Example 1 is shown. 2 is a drawing-substituting photograph showing a thermal slew rate sensor for measuring a microslash ultra-high thermal velocities used in the cooling test of Example 1. It is a graph which compares and shows the result of the cooling heat flow rate measurement of the micro slash spray flow obtained by the cooling test of Example 1, and a liquid nitrogen spray flow. 1 schematically illustrates an ultra-high heat flow rate electronic cooling system using a microslash spray flow and a two-phase liquid cooling system of the present invention.

Explanation of symbols

1: Microslash nitrogen generation nozzle 2: Ceramic heater 3: Holding plate 4: Heater lead wire 5: Heat flow rate sensor unit 6: Vertical visualization container 7: 4-side acrylic plate 8: Square screw 9: Nitrogen gas outlet
10: Stepping motor
11: Liquid nitrogen tank
12: Liquid helium tank
13: Liquid nitrogen conduit
14: Liquid helium conduit
15: Helium gas inlet valve
16: Mount with casters
21: Thermal insulation plate

Claims (4)

A cooling method for electronic equipment that uses a cryogenic microslash solid-liquid two-phase fluid, and the spray flow of the cryogenic microslash solid-liquid two-phase fluid formed and ejected by a microslash- generating atomizing nozzle A method for cooling electronic equipment, wherein heat is transferred by high-speed collision with a heating element. The method for cooling an electronic device according to claim 1, wherein the spray flow is microslash nitrogen.   3. The electronic device according to claim 1, wherein the electronic device is selected from the group consisting of a semiconductor component, a semiconductor element such as an IC and an LSI, a computer chip, and a microprocessor including a CPU and a GPU. Cooling method for electronic equipment. The method for cooling an electronic device according to any one of claims 1 to 3, wherein the latent heat of fusion of the cryogenic microslash particles in the spray flow is utilized for heat transfer from the electronic device heating element. .