Cooling system and cooling method for electronic apparatus

Abstract

[Problem] To provide a simple and efficient cooling system and cooling method with improved cooling performance for an electronic apparatus. [Solution] This cooling system includes a cooling mediator complex 100. The cooling mediator complex 100 includes a non-conductive bag 11 for wrapping an electronic apparatus including a substrate and a heating element 33 mounted on the substrate, and a heat sink device 21. The heat sink device 21 includes: a thermally conductive base block 21B placed inside the bag 11; and a thermally conductive outer block 21A placed outside the bag 11 and fixed to the base block 21B. When a first opening is formed in the bag 11 and the outer block 21A is fixed to the base block 21B, both are thermally connected through the first opening of the bag 11. The rear surface of the outer block 21A and the surface of the base block 21B hold both surfaces of the peripheral region of the opening of the bag 11 in a watertight manner, and the rear surface of the base block 21B provides a connection surface thermally connected to one surface of the heating element 33.

Description

Cooling system and cooling method for electronic device

[0001] The present invention relates to a cooling system and a cooling method for electronic devices, and in particular to a cooling system and a cooling method for electronic devices that require high performance, stable operation, or low power consumption operation and generate a large amount of heat themselves, such as supercomputers, data centers, artificial intelligence processing systems, quantum computing systems, cryptographic processing systems, and blockchain processing systems.

[0002] In recent years, one of the biggest challenges determining the performance limits of computer-related equipment is power consumption. The importance of research into power efficiency, particularly in supercomputers, has already been widely recognized. Specifically, speed performance per watt (Flops / W) has become one of the metrics for evaluating supercomputers. Furthermore, it is estimated that more than 30% of the total power consumed by data centers is spent on cooling, creating a growing demand for reducing power consumption through improved cooling efficiency. Furthermore, recent global warming and extreme heat caused by extreme weather have rendered conventional cooling methods insufficient to cool data centers during the summer, creating an urgent need to improve the cooling capacity of existing systems. Furthermore, the rapid growth of artificial intelligence processing, the increasing need for encryption processing, the rapid increase in cryptocurrency mining processing—a key example of blockchain processing—and the development of the metaverse, which is expected to see rapid growth, all of these factors require an exponential increase in the processing power of data centers and computer systems, creating a significant demand for increased cooling capacity.

[0003] Air and liquid cooling systems have traditionally been used to cool supercomputers and data centers. Liquid cooling systems use liquids, which have significantly better heat transfer properties than air, and are generally considered to have good cooling efficiency. For example, the "TSUBAME-KFC" system developed by the Tokyo Institute of Technology achieved 4.50 GFlops / W using a liquid immersion cooling system using synthetic oil, earning it first place in the "Supercomputer Green500 List" announced in November 2013 and June 2014. However, because the cooling liquid uses synthetic oil, which has high viscosity and forms an oil film, it is difficult to completely remove the oil adhering to electronic devices when they are removed from the oil-immersion rack, making electronic device maintenance (specifically, adjustment, inspection, repair, replacement, and expansion; the same applies below) extremely difficult. Furthermore, there have been reports of problems with the synthetic oils used, such as corroding electronic boards and gaskets that make up the cooling system in a short period of time, causing them to break down, and leaking refrigerant, hindering operation.

[0004] On the other hand, immersion cooling systems using fluorocarbon-based coolants instead of synthetic or mineral oils, which cause the above-mentioned problems, have been proposed. Specifically, examples of immersion cooling systems using fluorocarbon-based coolants (hydrofluoroether (HFE) compounds known under the trade names "Novec 7100" (a trademark of 3M; the same applies hereinafter)," "Novec 7200," and "Novec 7300") are disclosed in, for example, Patent Documents 1 and 2.

[0005] In addition, since 2014, one of the inventors has been developing a new liquid immersion cooling system and a series of related technologies that directly cools electronic devices by circulating a cooling liquid that is difficult to evaporate and contains a fully fluorinated substance as its main component within the open space of a cooling tank (for example, Patent Document 3).

[0006] However, PFAS (Perfluoroalkyl Substances and Polyfluoroalkyl Substances), which include all of these fluorocarbon-based coolants, have long been known to have adverse effects on the human body, agricultural crops, and the natural environment, and in December 2022, the world's largest manufacturer announced that it would completely cease production by the end of 2025, and in Europe, both production and use are expected to be banned by law within a few years. Therefore, there is a need for a new immersion cooling method that does not use any harmful compounds such as PFAS as a refrigerant, has superior cooling capacity compared to immersion cooling methods that use PFAS or other refrigerants, and is more affordable and can be used widely worldwide.

[0007] A typical example of a cooling method that does not use any harmful compounds such as PFAS as a refrigerant is one that can use ordinary water (tap water or industrial water) that is not pure water. Specifically, instead of a heat sink that is attached in direct contact with the upper surface of the semiconductor of the CPU (central processing unit), which is the main heat source in computer equipment, this method attaches a "water-cooled block" that contains a flow path for water to pass through inside a copper or aluminum block (see, for example, Patent Document 4).

[0008] Furthermore, another cooling method that can utilize water has been proposed, in which a semiconductor chip mounted on a circuit board is stored in a flexible bag, and the bag is immersed in a container filled with water as a cooling liquid. When the bag is filled with water or when the pressure inside the bag is reduced, the bag shrinks and deforms due to the pressure difference between the inside and outside of the bag, and the bag is tightly attached to the semiconductor device (for example, Patent Document 5).

[0009] Another cooling method that can utilize water has been proposed: natural water-cooled computers, which use river, lake, ocean, or tap water as a cooling source to directly cool the computer. Specifically, this cooling method involves immersing a computer whose board surface is coated with parylene resin in water (see, for example, Non-Patent Document 1).

[0010] Furthermore, a cooling method has been proposed in which the entire substrate is completely covered with an ultra-nano hydrophobic coating thin film made of silicon compound nanoparticles to create an electronic device with excellent waterproof and moisture-resistant properties, and the device is then immersed in water (e.g., Patent Document 6).

[0011] Japanese Patent No. 10,717,881 specification Kazuki Fujiwara et al., Information Processing Society of Japan Research Report High Performance Computing (HPC) "The First Step Towards a Direct Natural Water-Cooled Computer" 2017-HPC-158(5), pp.1-5 (March 1, 2017) URL: http: / / research.nii.ac.jp / ~koibuchi / pdf / ikki-sighpc158.pdf

[0012] The cooling system disclosed in Patent Document 4 uses water as a refrigerant, rather than the harmful substances such as PFAS used in Patent Documents 1 to 3. A water-cooled block mounted on the surface of a semiconductor element mounted in an electronic device is provided with a flowing water path to first cool the water-cooled block, and then only cool the semiconductor element that is in direct contact with the water-cooled block. Therefore, other electronic components and electronic boards that are not in direct contact with the water-cooled block and that generate a significant amount of heat but still require cooling cannot benefit from the cooling, and must be cooled separately using a method such as air cooling. Furthermore, in electronic devices used in recent supercomputers and data centers, in addition to the CPU (Central Processing Unit), there are many other components that need to be cooled, including the GPU (Graphics Processing Unit), high-speed memory, chipsets, power-related components such as FETs (Field Effect Transistors), electrolytic capacitors, network units, bus switch units, and SSDs (Solid State Drives). It is difficult to adequately cool all of these components, which have significantly different heat dissipation amounts, using air-cooling, which has inferior cooling capacity compared to liquid-cooling. Furthermore, a large amount of cooling water is typically required to supply water to the water-cooled block, and the water-cooled block itself is large and does not have a fin-like shape like a heat sink, which can obstruct the airflow path for air cooling. Furthermore, at least two piping paths are necessary to supply water to and recover it from the water-cooled block, and the piping paths installed for cooling the water-cooled block also obstruct the air flow paths for air cooling to a certain extent, resulting in extremely low cooling efficiency for objects that are not directly cooled by the water-cooled block.Even for objects that are directly cooled by the water-cooled block, the flow paths in the water-cooled block are often limited to a tube structure with a cross-sectional diameter of about 3 mm or 5 mm, which places a significant restriction on the flow rate through the flow paths compared to the flow rate when a heat sink with a general multiple fin structure directly contacts the water refrigerant.For this reason, it is easy to predict that its cooling performance will be significantly insufficient for the latest CPUs, which consume significantly more than 100W of power, or high-performance GPUs for generative AI, which consume more than 500W.

[0013] Furthermore, the cooling system disclosed in Non-Patent Document 1 completely covers the entire electronic components and electronic board with a thin film of parylene, which does not conduct electricity and is impermeable to water, and then the entire electronic components and electronic board coated with the parylene thin film are immersed in water or seawater, and the low temperature of the water or seawater that comes into contact with the entire parylene thin film is used to cool the equipment.

[0014] Similarly, the cooling system disclosed in Patent Document 6 also completely covers the entire electronic components and electronic board with an ultra-nano hydrophobic coating film made of silicon compound nanoparticles that are non-conductive and impermeable to water, and then the entire electronic components and electronic board coated with the hydrophobic coating film are immersed in water, and the low temperature of the water that comes into contact with the entire hydrophobic coating film is used to cool the equipment.

[0015] In both the cooling systems of Non-Patent Document 1 and Patent Document 6, all of the electronic components and electronic boards to be cooled are in contact with the refrigerant, water or seawater, via a parylene thin film or a hydrophobic coating thin film. For this reason, when highly efficiently cooling a CPU or other major heat source, the cooling capacity and efficiency are inevitably inferior compared to cooling systems in which a heat sink is in direct contact with the surface of a semiconductor, such as a water-cooled block, and the heat sink is directly cooled by a refrigerant such as water.

[0016] Furthermore, with the above-mentioned thin-film coating method, even a slight leakage of the coating can lead to water infiltration into the underlying electronic components and electronic boards, causing irreversible damage due to an electrical short circuit when electricity is applied, making this coating essential. However, since the occurrence of an electrical short circuit cannot be determined without visual inspection or actually applying electricity to the electronic device, there is always a risk of losing the object being cooled. This not only poses a problem when the electronic device is first used, but also leaves the thin coating vulnerable to subsequent breakdown due to deterioration or aging, or even slight contact with other electronic devices, inspection equipment, or tools during maintenance and inspection. Therefore, a dilemma exists when using parylene thin films and hydrophobic coating thin films: while the thin film thickness is desired to increase thermal conductivity from the refrigerant for cooling, a certain thickness is required to prevent leakage and breakdown of the coating to avoid damage to the electronic device.

[0017] Recent electronic substrates and their shapes have become increasingly complex in three-dimensional structures and continue to shrink in size, and it is expected that establishing a technology to coat them with a flawless thin film will pose considerable technical difficulties. As a result, cooling systems that use these thin film coatings have not yet been widely adopted.

[0018] In addition, these thin film coatings need to be firmly coated by vapor deposition, etc., and electronic components and electronic substrates that have undergone such surface modification are no longer covered by the quality guarantee, so their use must be at one's own risk. Furthermore, even if one wishes to repurpose or resell the components after use, it is extremely difficult to find demand for coated electronic components, so in principle, reuse or resale cannot be expected.

[0019] The water-cooling method disclosed in Patent Document 5 involves storing a semiconductor device in a flexible bag and immersing it in a coolant such as water to achieve cooling. However, like a thin film coating, the bag prevents the surface of the semiconductor device from directly contacting the coolant, which reduces the cooling performance.

[0020] As described above, in the conventional liquid cooling method, immersion cooling using PFAS will no longer be possible in the near future, and in addition, the cooling capacity is insufficient when synthetic oil or silicone, which are non-conductive liquids that do not use PFAS, are used. Furthermore, in the immersion method using water, which has high cooling capacity, non-conductivity must be ensured by coating the entire surface with a thin film without any leakage, but forming a perfect coating is becoming increasingly difficult with the advancement of three-dimensional substrate structures and miniaturization of electronic components, and this is hindering its widespread use.

[0021] Furthermore, while conventional liquid cooling methods using water-cooled blocks can provide a certain level of cooling performance for the CPU, which is the main heat source, the large water-cooled block and the piping required for water cooling make it difficult to adequately cool the majority of other electronic components and electronic boards that are cooled by air-cooling. Furthermore, problems have arisen in that the cooling performance of water-cooled blocks is insufficient for recent CPUs and GPUs that generate a large amount of heat. Furthermore, conventional liquid cooling methods, in which semiconductor devices are housed in flexible bags and immersed in water for cooling, have the problem of reduced cooling performance because the bags prevent the semiconductor device surface from coming into direct contact with the refrigerant.

[0022] Therefore, an object of the present invention is to provide a cooling system and a cooling method that solve the above-mentioned problems of the conventional technology, improve the cooling performance of electronic devices, and are simple, efficient, inexpensive, and easy to maintain.

[0023] To solve the above problems, one aspect of the present invention provides a cooling system in which an electronic device is immersed in ordinary water (tap water, industrial water, seawater, etc.), a typical example of a coolant with high thermal conductivity, and a heat sink device, which is often made of copper or aluminum and thermally connected to an electronic component such as a CPU, which is a major heat source, is directly cooled by the water. In a preferred embodiment of the cooling system according to the present invention, the cooling system includes a cooling medium composite. The cooling medium composite includes a non-conductive bag for enclosing an electronic device including a substrate and at least one heat-generating element mounted on the substrate, and a heat sink device. The heat sink device includes a thermally conductive base block placed inside the non-conductive bag and a thermally conductive outer block placed outside the non-conductive bag and fixed to the base block. A first opening is formed in the non-conductive bag. When the outer block is fixed to the base block, the outer block and the base block are thermally connected through the first opening of the non-conductive bag, the back surface of the outer block and the front surface of the base block keep both sides of the surrounding area of ​​the first opening of the non-conductive bag watertight, and the back surface of the base block provides a connection surface that is thermally connected to one side of at least one heating element.

[0024] In a preferred embodiment of the above cooling system, a raised portion may be formed on the rear surface of the outer block or the surface of the base block, and the raised portion may contact the surface of the base block or the rear surface of the outer block through the first opening of the non-conductive bag.

[0025] In a preferred embodiment of the cooling system, the first opening formed in the non-conductive bag may have an opening area larger than an area of ​​the protrusion.

[0026] Furthermore, in a preferred embodiment of the above cooling system, a thermally conductive sheet or thermally conductive grease may be arranged to fill the first opening of the non-conductive bag, and the back surface of the outer block may be in contact with the surface of the base block via the thermally conductive sheet or thermally conductive grease.

[0027] In addition, in a preferred embodiment of the above cooling system, the outer block may include a thermally conductive lower outer block and a thermally conductive upper outer block thermally connected to and fixed to the surface of the lower outer block, and when the lower outer block is fixed to the base block, the back surface of the lower outer block and the surface of the base block may keep both sides of the surrounding area of ​​the first opening of the non-conductive bag watertight.

[0028] Furthermore, in a preferred embodiment of the above cooling system, the base block may include a thermally conductive lower base block and a thermally conductive upper base block thermally connected to and fixed to the surface of the lower base block, and when the outer block is fixed to the upper base block, the back surface of the outer block and the surface of the upper base block may keep both sides of the surrounding area of ​​the first opening of the non-conductive bag watertight.

[0029] In addition, in a preferred embodiment of the above cooling system, the outer block may include a thermally conductive lower outer block and a thermally conductive upper outer block thermally connected to and fixed to the surface of the lower outer block, while the base block may include a thermally conductive lower base block and a thermally conductive upper base block thermally connected to and fixed to the surface of the lower base block, and when the lower outer block is fixed to the upper base block, the back surface of the lower outer block and the surface of the upper base block may keep both sides of the surrounding area of ​​the first opening of the non-conductive bag watertight.

[0030] Furthermore, in a preferred embodiment of the above cooling system, a plurality of convex surfaces of different heights may be formed on the rear surface of the base block or the rear surface of the lower base block, and the plurality of convex surfaces may be thermally connected to a plurality of surfaces of a plurality of heating elements of different heights.

[0031] In a preferred embodiment of the cooling system, the base block or the lower base block may have a substrate fixing mechanism, and the substrate of the electronic device may be fixed to the substrate fixing mechanism of the base block or the lower base block.

[0032] Furthermore, in a preferred embodiment of the cooling system, the substrate fixing mechanism of the base block or the lower base block may be two or more screw holes formed at a distance from each other on the rear surface of the base block or the lower base block.

[0033] In a preferred embodiment of the cooling system, the cooling medium composite may further include a bonding layer that provides a watertight connection between the back surface of the outer block and the outer surface of the non-conductive bag, or between the front surface of the base block and the inner surface of the non-conductive bag. The bonding layer may be formed from a dissimilar material bonding film, double-sided adhesive tape, or watertight punking, and the dissimilar material bonding film or the like may have a second opening formed therein that corresponds to the first opening of the non-conductive bag. The outer block and the base block may be thermally connected through the first opening of the non-conductive bag and the second opening of the bonding layer.

[0034] Furthermore, in a preferred embodiment of the above cooling system, a raised portion may be formed on the rear surface of the outer block or the surface of the base block, and the raised portion may be in contact with the surface of the base block or the rear surface of the outer block through the first opening of the non-conductive bag and the second opening of the bonding layer.

[0035] In a preferred embodiment of the cooling system, the first opening of the non-conductive bag and the second opening of the bonding layer may have an opening area larger than an area of ​​the protrusion.

[0036] Furthermore, in a preferred embodiment of the above cooling system, a thermally conductive sheet or thermally conductive grease may be arranged to fill the first opening of the non-conductive bag and the second opening of the bonding layer, and the back surface of the outer block may be in contact with the surface of the base block via the thermally conductive sheet or thermally conductive grease.

[0037] In addition, in a preferred embodiment of the above cooling system, the outer block includes a thermally conductive lower outer block and a thermally conductive upper outer block that is thermally connected to and fixed to the surface of the lower outer block, and when the lower outer block is fixed to the base block, the back surface of the lower outer block and the surface of the base block keep the surrounding area of ​​the first opening of the non-conductive bag and the surrounding area of ​​the second opening of the bonding layer watertight.

[0038] Furthermore, in a preferred embodiment of the above cooling system, the base block includes a thermally conductive lower base block and a thermally conductive upper base block thermally connected to and fixed to the surface of the lower base block, and when the outer block is fixed to the upper base block, the back surface of the outer block and the surface of the upper base block keep the surrounding area of ​​the first opening of the non-conductive bag and the surrounding area of ​​the second opening of the bonding layer watertight.

[0039] In a preferred embodiment of the cooling system, the outer block may include a thermally conductive lower outer block and a thermally conductive upper outer block thermally connected to and fixed to a surface of the lower outer block, while the base block may include a thermally conductive lower base block and a thermally conductive upper base block thermally connected to and fixed to a surface of the lower base block. When the lower outer block is fixed to the upper base block, the back surface of the lower outer block and the front surface of the upper base block preferably watertightly secure the area surrounding the first opening of the non-conductive bag and the area surrounding the second opening of the bonding layer. The material used for the outer block, upper outer block, or lower outer block may be different from the material used for the base block, upper base block, or lower base block.

[0040] Furthermore, in a preferred embodiment of the cooling system, the heat sink device may include a plurality of heat dissipating fins located on the exterior of the non-conductive bag.

[0041] Furthermore, in a preferred embodiment of the above-described cooling system, the cooling medium composite may be configured so that, when a vacuum is drawn inside the non-conductive bag, the inner surface of the non-conductive bag comes into close contact with both surfaces of the substrate and the surfaces of various electronic components mounted on the substrate.

[0042] In a preferred embodiment of the cooling system, the non-conductive bag may be configured to have a check valve that provides a path for vacuuming and maintains a tight seal. Alternatively, the non-conductive bag may be configured so that when immersed in the cooling liquid, the inner surface of the non-conductive bag passively comes into close contact with the surface of the substrate or the like by the hydraulic pressure of the surrounding cooling liquid, rather than by vacuuming. In this case, the non-conductive bag may have an opening or valve for discharging air that has been present between the non-conductive bag and the substrate, or may have a structure in which the non-conductive bag is partially open above the liquid surface.

[0043] Furthermore, in a preferred embodiment of the cooling system, the non-conductive bag may have a zipper mechanism that allows the electronic device to be placed inside the non-conductive bag when the zipper is open, and that maintains the airtightness of the non-conductive bag when the zipper is closed.

[0044] In addition, in a preferred embodiment of the above cooling system, the non-conductive bag has a heat sealing mechanism, and the heat sealing mechanism may be configured to allow an electronic device to be placed inside the non-conductive bag in an unheat-sealed state, and to allow vacuuming after heat sealing, and to maintain the airtightness of the non-conductive bag in a heat-sealed state.

[0045] Furthermore, in a preferred embodiment of the above cooling system, a penetration portion may be formed in the non-conductive bag for passing a power cable, a network communication cable, or a control cable connected to the electronic device, and a sealant provided in the penetration portion may be configured to maintain the airtightness of the non-conductive bag.

[0046] In addition, in a preferred embodiment of the above-mentioned cooling system, the cooling medium composite may further include, within the non-conductive bag, a wireless power supply unit for supplying power to the electronic device and a wireless communication unit for enabling wireless communication between the electronic device and the outside.

[0047] Furthermore, in a preferred embodiment of the above cooling system, the cooling system may further include a monitor unit within the non-conductive bag for monitoring the degree of vacuum within the non-conductive bag or for monitoring the electrical conductivity.

[0048] In addition, in a preferred embodiment of the above cooling system, the cooling system may further include a controller that controls the external vacuum pump to start and draw a vacuum inside the non-conductive bag when the output of the monitor unit indicates a vacuum level below a predetermined threshold.

[0049] Furthermore, in a preferred embodiment of the cooling system, the cooling system may further include a shutdown unit that stops operation of the electronic device and cuts off power when the output of the monitor unit indicates a vacuum level below a predetermined threshold or a conductivity above a predetermined threshold.

[0050] Additionally, according to another aspect of the present invention, there is provided a method for cooling an electronic device, the method including the steps of: providing a heat sink device including a thermally conductive base block and a thermally conductive outer block; providing a non-conductive bag for enclosing an electronic device including a substrate and at least one heat generating element mounted on the substrate, the non-conductive bag having a first opening for the heat sink device; and constructing a cooling medium composite, the step of fixing the outer block, which is placed outside the non-conductive bag, to a thermally conductive base block, which is placed inside the non-conductive bag, wherein when the outer block is fixed to the base block, the outer block The method includes the steps of: constructing a cooling medium composite, wherein the cooling medium composite is thermally connected to the base block through an opening formed in the non-conductive bag, and the back surface of the outer block and the front surface of the base block maintain both surfaces of the surrounding area of ​​the first opening of the non-conductive bag watertight; placing an electronic device in the cooling medium composite and fixing the base block to a substrate so that one surface of at least one heat generating element is in surface contact with and thermally connected to the back surface of the base block; at least partially making the non-conductive bag watertight; and immersing the watertight portion of the at least partially watertight cooling medium composite in a coolant.

[0051] According to another aspect of the present invention, there is provided a method for cooling an electronic device, the method including the steps of: preparing a heat sink device including a thermally conductive base block and a thermally conductive outer block; preparing a non-conductive bag for enclosing an electronic device including a substrate and at least one heat generating element mounted on the substrate, the non-conductive bag having an opening formed therein for mounting the heat sink device; thermally connecting one surface of the at least one heat generating element included in the electronic device to a back surface of the base block of the heat sink device by surface contact; placing the electronic device in the non-conductive bag and constructing a cooling medium composite by fixing the outer block placed outside the non-conductive bag to the base block, wherein when the outer block is fixed to the base block, the back surface of the outer block contacts a front surface of the base block through the opening formed in the non-conductive bag, and the back surface of the outer block and the front surface of the base block maintain a watertight seal on both sides of the area surrounding the opening of the non-conductive bag; at least partially making the non-conductive bag watertight; and immersing the watertight portion of the at least partially watertight cooling medium composite in a coolant.

[0052] In addition, in a preferred embodiment of the above cooling method, the step of fixing the outer block to the base block may include a step of bonding between the back surface of the outer block and the outer surface of the non-conductive bag, or between the surface of the base block and the inner surface of the non-conductive bag, using a dissimilar material bonding film.

[0053] Furthermore, in a preferred embodiment of the cooling method, the step of sealing the non-conductive bag may include the step of drawing a vacuum inside the non-conductive bag.

[0054] The cooling system according to the present invention uses a cooling intermediate composite body including a non-conductive bag for encasing an electronic device including a substrate and at least one heat-generating element mounted on the substrate, and a heat sink device. The heat sink device includes a thermally conductive base block, the main part of which is placed inside the non-conductive bag, and a thermally conductive outer block, the main part of which is placed outside the non-conductive bag and fixed to the base block. A first opening is formed in the non-conductive bag, and when the outer block is fixed to the base block, the outer block and the base block are thermally connected through the first opening of the non-conductive bag. The back surface of the outer block and the front surface of the base block maintain a watertight seal around the first opening of the non-conductive bag, and the back surface of the base block provides a connection surface thermally connected to one side of the at least one heat-generating element. When the cooling intermediate composite body is immersed in a coolant, the coolant directly removes heat from the surface of the outer block, locally and powerfully removing heat from the heat-generating element thermally connected to the back surface of the base block. When the outer block of the heat sink device is fixed to the base block, the outer block and the base block are thermally connected through the first opening of the non-conductive bag, so heat transfer from the base block to the outer block is not hindered or obstructed by the non-conductive bag. Furthermore, when the outer block of the heat sink device is fixed to the base block, the back surface of the outer block and the front surface of the base block maintain watertightness on both sides of the area surrounding the first opening of the non-conductive bag. Therefore, even if an opening (window) is formed in the non-conductive bag, the watertightness of the cooling medium composite as a whole can be ensured. Conventional cooling methods that immerse electronic devices in a conductive coolant, such as water or seawater, have the problem that the coating or bag used to keep the electronic device watertight from the surrounding coolant can obstruct heat transfer between the heat-generating element and the coolant and the flow of the coolant.In contrast, the cooling system of the present invention uses the cooling medium composite constructed as described above, which completely solves the problems of heat transfer between the heat generating element and the coolant in the prior art, thereby improving the cooling performance of electronic devices. In addition, even if an opening (window) is formed in the non-conductive bag, the cooling medium composite as a whole can provide a strong, stable, watertight structure.

[0055] Since the heat sink device is divided into an outer block and a base block, when the back surface of the base block is thermally connected to one or more heat generating elements mounted on a substrate, the base block can be first fixed to the substrate, and then the outer block can be fixed to the base block fixed to the substrate, which allows the base block to mechanically protect the heat generating elements from external forces applied when the outer block is fixed to the base block.

[0056] This is particularly advantageous when fixing a heat sink device to each individual heat sink element in an electronic device that has a large number of heat sink elements (e.g., 8, 16, or more) mounted relatively densely on a single board. A standard procedure involves first fixing base blocks to the board for all of the heat sink elements. After the base block fixing process is complete, the outer block is fixed to the base block. This two-step fixing method offers significant advantages in terms of work efficiency, yield, and mass productivity compared to a method that repeatedly fixes one heat sink device to one heat sink element. That is, once the base block fixing process is complete, the surfaces of all of the heat sink elements in the electronic device are mechanically protected by the base block. This avoids the risk of external force damaging other heat sink elements that have not yet been fixed to the base block during the outer block fixing process, and improves work accuracy, thereby significantly improving work efficiency, yield, and mass productivity.

[0057] When the outer block is configured to include a thermally conductive lower outer block and a thermally conductive upper outer block thermally connected to and fixed to the surface of the lower outer block, the upper outer block has an external heat dissipation function, the lower outer block and the base block have a watertightness function for the area surrounding the first opening of the non-conductive bag and a heat transfer function through the opening, and the base block has a heat removal function from the heat-generating element and a protection function for the heat-generating element. Similarly, when the base block is configured to include a thermally conductive lower base block and a thermally conductive upper base block thermally connected to and fixed to the surface of the lower base block, the outer block has an external heat dissipation function and a watertightness and heat transfer function, the outer block and the upper base block have a watertightness and heat transfer function, and the lower base block has a heat removal and protection function. Furthermore, if the outer block includes a lower outer block and an upper outer block, and the base block includes a lower base block and an upper base block, the upper outer block can have an external heat dissipation function, the lower outer block and the upper base block can have a watertight and heat transfer function, and the lower base block can have a heat absorption and protection function. This allows the heat dissipation function, watertight and heat transfer function, and heat absorption and protection functions to be appropriately assigned to the three or four blocks constituting the heat sink device, thereby adjusting the heat absorption characteristics. In other words, the configuration of the three or four blocks (which may further include one or more intermediate blocks placed between the upper and lower blocks), i.e., the combination of shapes and materials, can be appropriately selected and adjusted, greatly increasing the flexibility in the functional design of the heat sink device. Therefore, various heat sink devices can be easily and optimally constructed to suit the heat transfer characteristics of various refrigerants and electronic devices with heat sinks having various heat generation characteristics.Furthermore, if the materials used for the outer block, upper outer block or lower outer block are different from the materials used for the base block, upper base block or lower base block, a heat sink device with enhanced heat dissipation performance can be constructed, for example, by using aluminum for the base block (upper base block and lower base block) and copper, which has a higher thermal conductivity than aluminum, for the outer block (upper outer block and lower outer block).

[0058] Furthermore, if multiple convex surfaces of different heights are formed on the back surface of the base block or the back surface of the lower base block as necessary, and the multiple convex surfaces are thermally connected to multiple surfaces of multiple heat generating elements of different heights, this is suitable for efficiently removing heat from a large heat generating element including multiple semiconductor chips. A heterogeneous integration structure, also known as a multi-die package, in which multiple semiconductor chips are mounted two-dimensionally on a single package substrate (sometimes via an interposer), has already been put to practical use. In such a heterogeneous integration structure, the surface heights of the multiple semiconductor chips may differ. Thermal connection with multiple heat generating elements can be ensured by appropriately processing the back surface of the base block without making any changes to the outer block, or by appropriately processing the back surface of the lower base block without making any changes to the upper base block, and then assembling the entire system. Therefore, only one component (usually a plate-shaped member) of the heat sink device needs to be processed, improving work efficiency. By preparing outer blocks, upper base blocks, upper outer blocks, and lower outer blocks that can be used with other base blocks or lower base blocks and combining them, a heat sink device suitable for mass production can be provided. Furthermore, the back surface of the base block or lower base block may need to be machined into a complex shape, but work efficiency can be improved by selecting a relatively soft metal that is easy to machine as the base block material. Furthermore, when the coolant is water, the material of the outer blocks (upper outer block and lower outer block) that require direct contact with water must have rust-resistant properties. In contrast, the material of the base blocks (upper base block and lower base block) that are guaranteed to be watertight does not require rust-resistant properties. This flexibility in material selection for each of the multiple blocks offers a significant advantage: it allows for the provision of heat sink devices suitable for mass production.

[0059] Furthermore, if a bonding layer is included that provides a watertight connection between the back surface of the outer block and the outer surface of the non-conductive bag, or between the surface of the base block and the inner surface of the non-conductive bag, and the bonding layer is formed from a dissimilar material bonding film, double-sided adhesive tape, or watertight packing, and this dissimilar material bonding film, etc., has a second opening that corresponds to the first opening of the non-conductive bag, then an even stronger and more stable watertight connection can be achieved between the back surface of the outer block and the outer surface of the non-conductive bag, or between the surface of the base block and the surface of the bag, and the watertightness function of the outer block and the base block and the durability of that function can be further improved.

[0060] The non-conductive bag can be made of a synthetic resin (e.g., polyethylene, polypropylene, polyester, etc.) that is water-resistant and resistant to relatively low temperatures (e.g., 100°C or higher) and can maintain airtightness (airtightness / watertightness) when sealed as needed, allowing the cooling medium composite to be prepared simply, efficiently, and inexpensively. Furthermore, when performing maintenance on an electronic device, all that is required is to tear the non-conductive bag of the cooling medium composite and remove the electronic device from the bag, which not only provides excellent maintainability but also almost completely prevents the surface of the electronic device from being soiled by foreign matter, making it advantageous from the perspective of recycling used electronic devices.

[0061] When cooling an electronic device, the non-conductive bag of the cooling medium composite may be entirely watertight or at least partially watertight. When the entirely watertight non-conductive bag is entirely watertight, the entire cooling medium composite can be immersed in a cooling liquid to cool the electronic device. On the other hand, when the non-conductive bag is at least partially watertight, the watertight portion of the cooling medium composite can be immersed in the cooling liquid to cool the electronic device. For example, the non-conductive bag may be a flexible synthetic resin bag. When the cooling medium composite is gradually immersed in the cooling liquid while leaving a portion of the bag (e.g., the upper portion) open, the bag is pressed by the hydraulic pressure of the surrounding cooling liquid, which expels air from the bag to the outside and simultaneously brings the inner surface of the bag into relatively close contact with both sides of the board and the surfaces of various electronic components mounted on the board.

[0062] The above and other objects and advantages of the present invention will be more clearly understood through the following description of the embodiments, although the embodiments described below are merely examples and the present invention is not limited thereto.

[0063] 1 is a front view showing the configuration of a main part of a cooling system according to an embodiment of the present invention. FIG. 2 is a side view showing the configuration of a main part of a cooling system according to an embodiment of the present invention. FIG. 3 is a view showing an outer block of a heat sink device applied to an example of a cooling medium composite. FIG. 4 is a view showing an outer block of a heat sink device applied to an example of a cooling medium composite. FIG. 5 is a view showing a base block of a heat sink device applied to an example of a cooling medium composite. FIG. 6 is a perspective view showing a heat sink device applied to an example of a cooling medium composite. FIG. 7 is an exploded view showing an example of a cooling medium composite. FIG. 8 is a plan view showing an example of a cooling medium composite. FIG. 9 is a rear view showing an example of an cooling medium composite. FIG. 10 is a cross-sectional view showing an example of a cooling medium composite. FIG. 11 is an explanatory view showing an example of installing an electronic device in the cooling medium composite. FIG. 12 is a cross-sectional view showing an example of installing an electronic device in the cooling medium composite. FIG. 13 is a cross-sectional view showing an example of installing an electronic device in the cooling medium composite. FIG. 14 is a cross-sectional view showing another example of installing an electronic device in the cooling medium composite. FIG. 15 is an explanatory view showing an example of configuring a cooling medium composite by installing an electronic device with a base block. FIG. 16 is a perspective view showing a state in which multiple heat sink devices are mounted on a substrate of an electronic device on which multiple semiconductor devices are densely mounted. FIG. 17 is a view showing an example of operation of a cooling system. FIG. 18 is a plan view showing an example of a dissimilar material bonding film. FIG. 19 is a plan view showing an example of a thermally conductive sheet. 1 is a schematic cross-sectional view showing another example of installing an electronic device in a cooling medium composite. FIG. 1 is a schematic cross-sectional view showing yet another example of installing an electronic device in a cooling medium composite. FIG. 2 is a schematic cross-sectional view showing yet another example of installing an electronic device in a cooling medium composite. FIG. 3 is a schematic cross-sectional view showing three other examples of installing an electronic device in a cooling medium composite. FIG. 4 is a schematic cross-sectional view showing three other examples of installing an electronic device in a cooling medium composite. FIG. 5 is a schematic cross-sectional view showing three other examples of installing an electronic device in a cooling medium composite. FIG. 6 is a schematic cross-sectional view showing three other examples of installing an electronic device in a cooling medium composite. FIG. 7 is a schematic cross-sectional view showing two other examples of installing an electronic device in a cooling medium composite. FIG. 8 is a schematic cross-sectional view showing yet another example of installing an electronic device in a cooling medium composite.10 is a schematic cross-sectional view showing yet another example of installing an electronic device in a cooling medium composite;FIG. 11 is a schematic cross-sectional view showing yet another example of installing an electronic device in a cooling medium composite;FIG.

[0064] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the cooling system according to the present invention will now be described in detail with reference to the drawings.

[0065] 1A and 1B , the cooling system 1 includes a cooling medium composite 100. The cooling medium composite 100 includes a non-conductive bag 11 for encasing an electronic device 10 and a heat sink device 21. As described below, the heat sink device includes a thermally conductive base block placed inside the non-conductive bag and a thermally conductive outer block placed outside the non-conductive bag and fixed to the base block. When the base block and outer block are combined, the heat sink device functions as a heat sink that can be thermally connected to a heat-generating element of the electronic device. The heat sink device is generally made of copper or aluminum. Alternatively, blocks of different metals may be combined, such as a copper / aluminum outer block and an aluminum / aluminum base block. The base block of the heat sink device may be, for example, a plate-like member with a uniform thickness. The outer block of the heat sink device may be, for example, a plate-like member with numerous plate- or rod-like fins on its surface to increase its surface area, or simply a plate-like member. Hereinafter, in this specification, the terms "outer block," "upper outer block," "lower outer block," "base block," "upper base block," and "lower base block" are used, but it should be noted that the word "block" included in these terms includes "plate" and "sheet," and does not in any way limit the ratio of the length, width, or diameter to the height (or thickness) of the member, nor does it limit the shape of the member.

[0066] The non-conductive bag 11 is made of a synthetic resin (e.g., polyethylene, polypropylene, polyester, etc.) film that is water-resistant and relatively heat-resistant (e.g., 100°C or higher) and can maintain airtightness (airtightness / watertightness) when sealed as needed. A zipper mechanism 20 is provided on one side of the non-conductive bag 11. The zipper mechanism 20 is configured to allow the electronic device 10 to be placed inside the non-conductive bag 11 when the zipper is open, and to maintain the airtightness of the non-conductive bag 11 when the zipper is closed. In addition, a check valve 19 is provided on one side of the non-conductive bag 11. The check valve 19 provides a path for evacuating the inside of the non-conductive bag 11 as needed, and maintains the airtightness during and after the evacuation.

[0067] The electronic device 10 includes a substrate 31, at least one heating element 33 (e.g., a CPU, as shown in FIG. 6 and elsewhere) mounted on the substrate 31, and various electronic components 35, such as an electrolytic capacitor. One end of each of a network communication cable 36 and a power cable 37 is connected via a connector to the electronic device 10 installed in the non-conductive bag 11. The network communication cable 36 and the power cable 37 each pass through a penetration formed in one surface of the non-conductive bag 11. Because a sealant 17 is provided in the penetration, the other end of each of the network communication cable 36 and the power cable 37 can be connected to network equipment and power distribution equipment outside the non-conductive bag 11 while maintaining the airtightness of the non-conductive bag 11.

[0068] 2A and 2B show an outer block 21A of a heat sink device 21 applied to the cooling medium composite 100, with Fig. 2A(A) being a plan view, Fig. 2A(B) being a front view, Fig. 2B(A) being a bottom view, and Fig. 2B(B) being a perspective view. Also, Fig. 2C and Fig. 2D show a base block 21B of the heat sink device 21, with Fig. 2C(A) being a plan view, Fig. 2C(B) being a front view, Fig. 2C(C) being a cross-sectional view taken along line A-A in Fig. 2C(A), and Fig. 2D being a perspective view showing the heat sink device 21 including the outer block 21A and the base block 21B.

[0069] 2A and 2B , a fin region 212 on the front surface of the outer block 21A is provided with a number of plate-shaped fins rising up from a base portion 211. A pair of regions diagonally positioned on the front surface of the base portion 211 are flat surfaces without fins, and screw holes 215, which are through-holes that connect the front surface to the back surface of the base portion 211, are formed within these regions. In addition, a raised portion 213 is formed on the back surface side of the base portion 211 of the outer block 21A. In this specification, the flat surface 212B on which the raised portion 213 is not formed may be referred to as the first back surface of the outer block, and the flat surface 213B located at the top of the raised portion 213 may be referred to as the second back surface of the outer block, and one or both of the flat surfaces may be referred to as the back surface of the outer block.

[0070] 2C , a pair of screw holes 225 are formed diagonally on one flat surface 221A of base block 21B, which is made of square plate-like member 221, and a pair of screw holes 227 are formed diagonally on the other flat surface 221B of base block 21B. In this specification, flat surface 221A in which screw holes 225 are formed may be referred to as the front surface of the base block, and flat surface 221B in which screw holes 227 are formed may be referred to as the back surface of the base block.

[0071] Figure 2D shows the outer block 21A placed on the base block 21B so that the back surface 212B (second back surface) of the outer block 21A is in contact with the front surface 221A of the base block 21B, and this state also shows the appearance of the heat sink device 21 when the heat sink device 21 is attached to an opening formed in the non-conductive bag 11, as described below.

[0072] FIG. 3 shows the non-conductive bag 11, the outer block 21A of the heat sink device 21, and the base block 21B, which are components of the cooling medium composite 100, in an exploded state. FIG. 4A shows the cooling medium composite 100 from the outer surface 11A of the non-conductive bag 11, FIG. 4B shows the cooling medium composite 100 from the inner surface 11B of the non-conductive bag 11, FIG. 5A shows a cross section B-B in FIG. 4A, and FIG. 5B shows a cross section C-C in FIG. 4A. A first opening 15 is formed in the non-conductive bag 11. The size (area) of the first opening 15 is preferably the same as or slightly larger than the size (area) of the raised portion 213 of the outer block 21A.

[0073] The outer block 21A can be fixed to the base block 21B, for example, with screws 25. At this time, the flat surface 213B of the raised portion 213 of the outer block 21A (i.e., the second back surface of the outer block) contacts the surface 221A of the base block 21B through the first opening 15 of the non-conductive bag 11, thermally connecting the outer block 21A and the base block 21B. Additionally, the flat surface 212B of the outer block 21A (i.e., the first back surface of the outer block) and the surface 221A of the base block 21B apply an appropriate surface pressure to the area surrounding the first opening 15 of the non-conductive bag 11, and this appropriate surface pressure keeps both sides of the surrounding area watertight. The appropriate surface pressure can be obtained by appropriately adjusting the height of the raised portion 213 depending on the material, thickness, etc. of the non-conductive bag 11. On the other hand, the back surface 221B of the base block 21B inside the non-conductive bag 11 provides a connection surface that is thermally connected to one surface of the heating element.

[0074] FIG. 6 shows an example of installing an electronic device 10 in the cooling medium composite 100, FIG. 7 shows a cross section taken along the line CC in FIG. 6 , and FIG. 8 shows a cross section taken along the line DD in FIG. 6 . As shown in FIG. 6 , the electronic device 10 is installed in the cooling medium composite 100. At this time, as shown in FIG. 7 , the circuit board 31 of the electronic device 10 is fixed to the base block with screws 27, and one surface of the heating element 33 is in surface contact with the back surface of the base block 21B of the heat sink device 21 for thermal connection. To ensure this surface contact and thermal connection, it is preferable to fill the minute gap between the one surface of the heating element 33 and the back surface of the base block 21B with thermally conductive grease 34. After installing the electronic device 10 in the cooling medium composite 100, if necessary, the zipper mechanism of the non-conductive bag 11 is closed, and then the non-conductive bag 11 is evacuated via the check valve 19. By drawing a vacuum, the inner surface of the non-conductive bag can be brought into intimate contact with both sides of the substrate and the surfaces of the various electronic components mounted on the substrate. However, as described below, in one example of operation of the cooling system, the zipper mechanism can be left partially open. In this case, even without drawing a vacuum inside the bag, the bag can be pressed by the hydraulic pressure of the surrounding coolant during operation of the cooling system, thereby bringing the inner surface of the non-conductive bag into somewhat intimate contact with both sides of the substrate and the surfaces of the various electronic components mounted on the substrate.

[0075] In the cooling medium composite 100, an example of a substrate fixing mechanism for fixing the substrate 31 of the electronic device 10 to the base block 21B is shown in Figures 2(C), 4B, 5B, and 8. This mechanism involves inserting screws 27 from the substrate 31 side into two or more screw holes 227 formed at intervals on the back surface of the base block 21B. However, other substrate fixing mechanisms are also possible. That is, as in the cooling medium composite 101 shown in Figure 9, support screws 28 can be fixed into two or more screw support holes (through holes) formed at intervals on the back surface of the base block 21B, and these support screws can be inserted into through holes in the substrate 31 and fixed with nuts or the like. Yet another substrate fixing mechanism is shown in the cooling medium composite 102 shown in Figure 10, in which the heads of push pins are fixed into two or more push pin support holes formed at intervals on the back surface of the base block 21B, and the tips of the push pins are inserted into through holes in the substrate 31 for fixing. Here, a push pin is a fastener that combines a half-shaped shaft with a barb at the tip and a spring, and is known as a fastener for fastening components such as circuit boards of electronic devices to other components such as housings, so a detailed explanation will be omitted here.

[0076] 11 shows another example of mounting an electronic device 10 on a cooling medium composite 100. This mounting method takes advantage of the fact that the heat sink device 21 is divided into two components, an outer block 21A and a base block 21B. The difference from the mounting method shown in FIG. 6 is that the base block 21B is fixed to the substrate 31 of the electronic device 10 before the process of fixing the outer block 21A to the base block 21B. Of course, once this process of fixing to the substrate is completed, the back surface 221B of the base block 21B is thermally connected to one surface of the heat generating element.

[0077] 12 is a perspective view showing a state in which a plurality of heat sink devices 21 are attached to a substrate 31 of an electronic device on which a plurality of semiconductor devices are densely mounted (non-conductive bags are not shown). In this example, 12 processors are mounted on the substrate 31, and one heat sink device 21 is fixed to each processor. However, this is just one example, and other examples suitable for cooling electronic devices on which a plurality of semiconductor devices are densely mounted or electronic devices on which large semiconductor devices are mounted will be described later.

[0078] FIG. 13 shows an example of operation of the cooling system 1. The cooling tank 3 contains a sufficient amount of coolant 4 to immerse the cooling medium composite 100. The coolant 4 may be ordinary water (tap water, industrial water, seawater, etc.). A pipe 5 connected to the cooling tank 3 provides a path for discharging the coolant heated in the cooling tank 3 and returning the coolant cooled by a heat exchanger (not shown) to the cooling tank 3. In the cooling medium composite 100 immersed in the coolant 4, the coolant 4 directly absorbs heat from the surface of the outer block 21A of the heat sink device 21 (in other words, heat is dissipated from the outer block 21A), and the base block 21B of the heat sink device 21 locally and powerfully absorbs heat from the heat-generating element 33 thermally connected to the back surface of the base block 21B. In conventional cooling methods, there is a problem that the coating or bag covering the electronic device or semiconductor device inhibits heat transfer between the heat generating element and the coolant and inhibits the flow of the coolant, but this method solves this problem and improves the cooling performance of the electronic device. Furthermore, if necessary, the inside of the non-conductive bag 11 can be sealed and then evacuated to bring the inner surface of the non-conductive bag 11 into close contact with both sides of the substrate 31 and the surfaces of the various electronic components 35 mounted on the substrate 31, thereby increasing the efficiency of heat removal from the various electronic components 35 and further improving the cooling performance of the electronic device 100.

[0079] In one example of operation of the cooling system 1, the watertight portion of the cooling medium composite 100 may be immersed in the coolant 4 while the non-conductive bag 11 is at least partially watertight. For example, the zipper mechanism 20 of the non-conductive bag 11 may be left partially open instead of being completely closed. The cooling medium composite 100 is then immersed in the coolant 4 so that the zipper mechanism 20 is positioned above the surface of the coolant 4. In this way, the bag is pressed by the hydraulic pressure of the surrounding coolant, which expels air from the bag to the outside and simultaneously brings the inner surface of the non-conductive bag into relatively close contact with both sides of the board and the surfaces of various electronic components mounted on the board.

[0080] Next, other examples of installing electronic devices in the cooling medium composite will be described with reference to Figures 14 to 26. Various modifications are possible to install electronic devices by modifying parts of the cooling medium composite. Note that the same reference numerals are used for parts that are the same as those in Figures 1A to 11.

[0081] FIG. 14 is a plan view showing an example of a bonding layer that can be used in another example of installing an electronic device in a cooling medium composite. As described below, the bonding layer is formed using a dissimilar material bonding film, double-sided adhesive tape, or watertight packing to connect the surface of the base block to the inner surface of the non-conductive bag, or to connect the back surface of the outer block to the outer surface of the non-conductive bag. The dissimilar material bonding film, double-sided adhesive tape, or watertight packing that forms the bonding layer 41 has a second opening 43 formed therein. In the illustrated example, the size of the bonding layer 41 is preferably the same as or slightly larger than the size of the back surface of the outer block or the size of the surface of the base block, and the size of the second opening 43 is preferably the same as or slightly larger than the size of the protrusion of the base block. Specific examples of the dissimilar material bonding film, double-sided adhesive tape, or watertight packing that form the bonding layer 41 and a method for forming the bonding layer will be described below.

[0082] 15 is a plan view showing an example of a thermally conductive sheet that can be used in another example of similarly installing an electronic device in a cooling medium composite. The thermally conductive sheet 51 may be a resin, ceramic, or metal sheet with excellent thermal conductivity, or a resin or ceramic sheet containing a metal filler. The size of the thermally conductive sheet 41 is preferably the same as or slightly smaller than the size of the second opening 43 formed in the dissimilar material bonding film 41. Methods for using the thermally conductive sheet and other configurations that can be used in place of the thermally conductive sheet will be described later.

[0083] 16 to 27 are schematic cross-sectional views showing other examples of installing an electronic device in a cooling medium composite. For ease of illustration, the schematic cross-sectional views from Fig. 16 onwards are a composite of a cross-section of the center of the heat sink device and a cross-section of the four corners of the heat sink device taken along lines passing through the centers of the multiple screws that will be attached there. Furthermore, diagonal lines are intentionally omitted from the cross sections of the heat sink device, screws, and their accessories.

[0084] Other examples will be explained below in order. The cooling medium composite 300 shown in Figure 16(C) differs from the cooling medium composite 100 shown in Figures 2 to 8 and 11 in that the outer block 21A and base block 21B of the heat sink device 21 (as well as the size of the raised portion 213) are wider and larger to accommodate the larger-sized heat generating element 33 mounted on the substrate 31, that the base block 21B is fixed to the substrate 31 by screws 25 with spacers 32 interposed therebetween, and that a bonding layer 41 is included that connects the surface of the base block 21B to the inner surface of the non-conductive bag 11.

[0085] 16, the procedure for constructing the cooling medium composite 300 will be described. First, the base block 21B is fixed to the substrate 31 with screws 25 and spacers 32 (FIG. 16(A)). The height of the spacers 32 may be the same as the height of the heating element 33, and with the screws fixed, the back surface of the base block 21B is thermally connected to the front surface of the heating element. However, the spacers 32 prevent the base block 21B from moving downward due to overtightening of the screws or external forces applied to the base block 21B in processes after the screws are fixed, thereby helping to prevent damage to the heating element.

[0086] Next, a dissimilar material bonding film 41 is placed on the surface of the base block 21B, and a non-conductive bag 11 is placed on top of that, and aligned so that the first opening of the bag 11 and the second opening of the dissimilar material bonding film 41 overlap. A process such as heat pressing is performed to turn the dissimilar material bonding film into a bonding layer 41, and the surface of the base block 21B is bonded to the surrounding area of ​​the first opening of the bag 11 (Figure 16 (B)).

[0087] An example of a dissimilar material bonding film for forming the bonding layer 41 is the "Metaseal" (a product name of Fujimori Kogyou Co., Ltd.) series. Because this dissimilar material bonding film is formed into a film of uniform thickness, it can be sandwiched between the surface of the base block 21B and the inner surface of the non-conductive bag 11 and heat-pressed to form a bonding layer bonding the base block 21B and the non-conductive bag 11. A heat press or an iron-type heater can be used for heat-pressing, and the bonding process between the base block 21B and the non-conductive bag 11 can be completed easily and in a short time (several seconds or less). The method for forming the bonding layer 41 is not limited to heat-pressing, and various methods, such as pressure, ultrasonic waves, electromagnetic waves, and light irradiation, can also be used.

[0088] By forming the bonding layer 41 from a dissimilar material bonding film, it is possible to achieve a surface bond between the surface of the base block 21B and the inner surface of the non-conductive bag 11 with a uniform thickness and without variations in adhesive strength, which makes it suitable for use in firmly bonding a heat sink and a bag.

[0089] Another example of a dissimilar material bonded film that forms the bonding layer 41 is "WelQuick" (a Resonac product name) manufactured by Resonac Corporation. This dissimilar material bonded film utilizes the solid-liquid phase change of the film material, allowing the bonding process to be completed in a short time (a few seconds). It also allows for reheating after bonding to allow for peeling and re-adhesion. This allows for easy recovery of the cooling medium composite 300 of a cooling system after a certain period of use, and for easy peeling of the base block 21B from the non-conductive bag 11, resulting in high resource reusability.

[0090] Here, the dissimilar material bonding film can be preferably a pre-formed sheet or film that can be cut and used. However, this is not limited thereto. For example, if a certain environment is established in which various conditions, including the film thickness and shape, can be appropriately controlled, a bonding layer 23 formed from the dissimilar material bonding film can be obtained starting with a liquid or gel adhesive material. Specifically, as an example, a mold is first placed on the surface of the base block 21B and filled with the liquid or gel adhesive material, thereby forming a coating of the adhesive material of the desired shape (i.e., a shape with a first opening in the center) and volume on the surface of the base block 21B. Next, with the coating of the adhesive material in contact with the surface of the heat sink and the inner surface of the non-conductive bag, the coating of the adhesive material can be solidified by methods such as thermocompression, pressure, ultrasonic waves, electromagnetic waves, or light irradiation. In this way, a bonding layer formed from the dissimilar material bonding film can be obtained starting from the liquid or gel adhesive material.

[0091] After joining the surface of base block 21B and the area surrounding the first opening of bag 11 via bonding layer 41, outer block 21A is then placed on base block 21B from the outside of bag 11 and secured with screws 25 (FIG. 16(C)). In this secured state, the flat surface of protruding portion 213 of outer block 21A contacts the surface of base block 21B and is thermally connected. Meanwhile, the flat surface around protruding portion 213 of outer block 21A applies an appropriate surface pressure to the area surrounding the first opening of bag 11, and this appropriate surface pressure (and furthermore, on the inner side of the bag, due to the presence of bonding layer 41) keeps both sides of the surrounding area watertight.

[0092] Alternatively, the bonding layer may be formed using double-sided adhesive tape. For example, a high-strength acrylic foam tape (e.g., 3M VHB Tape) can be cut to the desired size and shape to prepare the double-sided adhesive tape for the bonding layer. The bonding layer bonding the base block 21B and the non-conductive bag 11 can be formed by pressing one side of the double-sided adhesive tape to the surface of the base block 21B or the inner surface of the non-conductive bag 11, and then pressing the other side of the double-sided adhesive tape to the inner surface of the non-conductive bag 11 or the surface of the base block 21B. The use of double-sided adhesive tape has the advantage that it does not require a heat treatment, making it easy to form the bonding layer. When using double-sided adhesive tape, it is preferable to arrange the cut tape so that the bonding layer forms a continuous, closed band surrounding the first opening of the bag 11.

[0093] Alternatively, the joining layer may be formed by a watertight packing. For example, various rubber packings (typically O-rings) in a continuous, closed strip or line shape may be used. The watertight packing is placed between the surface of the base block 21B and the inner surface of the non-conductive bag 11 so as to surround the first opening of the bag 11. Next, the outer block 21A is placed on the base block 21B from the outer surface side of the bag 11 and fixed with screws 25. In this fixed state, the watertight packing elastically deforms, applying an appropriate surface pressure in a strip or line shape to the area surrounding the first opening 15 of the bag 11, thereby maintaining a watertight seal on both sides of the surrounding area.

[0094] Obviously, when the size of the heat-generating element 33 is large or when the heat-generating element 33 generates a large amount of heat, a larger heat sink device 21 should be selected. However, if the heat sink device is composed of separate components, the outer block 21A and the base block 21B, it is possible to later replace only the outer block 21A with another outer block with different thermal properties, such as a different fin configuration and / or block material, which is highly convenient. For example, if, after starting operation of electronic equipment in a data center, it is discovered that the heat generation amount of the heat-generating element 33 significantly deviates from the initial design value for some reason, it is possible to later remove only the outer block 21 from the cooling medium composite 300 and replace it with another outer block with different thermal properties (e.g., a different fin height or number, or a different block material, resulting in a different overall fin surface area or heat dissipation performance). At this time, there is no need to remove the bag 11 from the base block 21B or the base block 21 from the substrate 31, so the replacement process is simplified and the risk of losing the watertightness of the cooling medium composite 300 due to the replacement work can be effectively avoided.

[0095] 17 is a schematic cross-sectional view showing yet another example of installing an electronic device in a cooling medium composite. Cooling medium composite 301 differs from cooling medium composite 300 shown in FIG. 16 in that it uses outer block 23A with a flat back surface and base block 23B with raised portion 213 formed on its surface. The procedure for constructing cooling medium composite 301 is the same as the procedure for constructing cooling medium composite 300, except that the second opening of dissimilar material bonding film 41 and the first opening of bag 11 are aligned with raised portion 213 on the surface of base block 21B. Therefore, detailed description thereof will be omitted here.

[0096] Figure 18 is a schematic cross-sectional view showing yet another example of installing an electronic device in a cooling medium composite. The cooling medium composite 302 differs from the cooling medium composite 300 shown in Figure 16 in that it uses an outer block 23A with a flat back surface and a base block 21B with a flat front surface. A thermally conductive sheet 51 is placed to fill the second opening of the dissimilar material bonding film 41 and the first opening of the bag 11, and the back surface of the outer block 23A contacts the front surface of the base block 21B via the thermally conductive sheet 51. Thermally conductive grease may be used instead of the thermally conductive sheet 51. This configuration of the cooling medium composite 302 also ensures a heat transfer path from the base block 21B to the outer block 23A.

[0097] FIG. 19 is a schematic cross-sectional view showing three other examples of installing electronic devices in a cooling medium composite. In the example shown in FIG. 19(A), the cooling medium composite 400 differs from the cooling medium composite 300 shown in FIG. 16. In the example shown in FIG. 19(B), the cooling medium composite 401 differs from the cooling medium composite 301 shown in FIG. 17. In the example shown in FIG. 19(C), the cooling medium composite 402 differs from the cooling medium composite 302 shown in FIG. 18 in that the outer blocks 43A / 43B have flat surfaces and no fins. Thus, if the outer blocks do not require a large surface area for thermal design purposes, a plate-shaped outer block without fins may be used. This also applies to the other examples shown in FIGS. 20 to 26 below.

[0098] 20A and 20B are schematic cross-sectional views showing three other examples of installing electronic devices in a cooling medium composite. In the example shown in Fig. 20A, cooling medium composite 500 differs from cooling medium composite 300. In the example shown in Fig. 20B, cooling medium composite 501 differs from cooling medium composite 301. In the example shown in Fig. 20C, cooling medium composite 402 differs from cooling medium composite 302 in that dissimilar material bonding film 41 is placed between the back surface of outer block 21A / 23A and the outer surface of non-conductive bag 11, and the back surface of outer block 21A / 23A and the outer surface of non-conductive bag 11 are bonded by a bonding layer.

[0099] To outline an example of the procedure for constructing the cooling medium composites 500, 501, and 502, first, the base blocks 21B / 23B are fixed to the substrate 31 with screws 25 interposed with spacers 32. Next, with the back surfaces of the outer blocks 21A / 23A facing upward, a dissimilar material bonding film 41 is placed on top of the dissimilar material bonding film, and a non-conductive bag 11 is placed on top of the dissimilar material bonding film. The back surfaces of the outer blocks 21A / 23A and the outer surface of the non-conductive bag 11 are bonded to each other with a bonding layer formed from the dissimilar material bonding film. Next, the substrate 31 with the base blocks is placed inside the bag, and the outer blocks 21A / 23A with the bags are placed on the base blocks 21B / 23B and fixed with screws 25. Even with this configuration, the appropriate surface pressure applied by the flat back surfaces of the base blocks (and further, the bonding layer 41 on the outer surface of the bag) allows both sides of the surrounding areas of the first and second openings to be kept watertight.

[0100] 21A and 21B are schematic cross-sectional views showing three other examples of installing electronic devices in a cooling medium composite. In the example shown in Fig. 21A, cooling medium composite 600 differs from cooling medium composite 300. In the example shown in Fig. 21B, cooling medium composite 601 differs from cooling medium composite 301. In the example shown in Fig. 21C, cooling medium composite 602 differs from cooling medium composite 302 in that a dissimilar material bonded film is not used. As already explained with respect to cooling medium composite 100, even with this configuration, both surfaces of the area surrounding the first opening of non-conductive bag 11 can be kept watertight.

[0101] 22A to 22C are schematic cross-sectional views showing three other examples of installing electronic devices in the cooling medium composite. 22(A), cooling medium composite 700 differs from cooling medium composite 500 shown in FIG. 20(A). In the example shown in FIG. 22(B), cooling medium composite 701 differs from cooling medium composite 501 shown in FIG. 20(B). In the example shown in FIG. 22(C), cooling medium composite 602 differs from cooling medium composite 502 shown in FIG. 20(C) in that the outer blocks include a thermally conductive lower outer block 43A / 43B and a thermally conductive upper outer block 23A that is thermally connected to and fixed to the surface of the lower outer block 43A / 43B. When the lower outer block 43A / 43B is fixed to the base block 21B / 23B, the back surface of the lower outer block 43A / 43B and the surface of the base block 21B / 23B keep the area around the first opening of the non-conductive bag and the area around the second opening of the bonding layer watertight. By configuring it in this manner, the upper outer block has the function of external heat dissipation, the lower outer block and base block have the function of keeping the area surrounding the first opening of the non-conductive bag watertight and of transferring heat through the opening, and the base block has the function of removing heat from the heating element and protecting the heating element.

[0102] Fig. 23 is a schematic cross-sectional view showing three other examples of installing an electronic device in a cooling medium composite. In the example shown in Fig. 23(A), cooling medium composite 800 differs from cooling medium composite 700. In the example shown in Fig. 23(B), cooling medium composite 801 differs from cooling medium composite 701. In the example shown in Fig. 23(C), cooling medium composite 802 differs from cooling medium composite 702 in that a dissimilar material bonded film is not used. Even with this configuration, both sides of the area surrounding the first opening of non-conductive bag 11 can be kept watertight.

[0103] 24A and 24B are schematic cross-sectional views showing two other examples of installing an electronic device in a cooling medium composite. In the example shown in FIG. 24A, the cooling medium composite 900 differs from the cooling medium composite 802 shown in FIG. 23C. In the example shown in FIG. 24B, the cooling medium composite 901 differs from the cooling medium composite 802 in that the base block includes a thermally conductive lower base block 23B and a lower base block 24B. A raised portion formed on the back surface of the upper base block 23B is in contact with and thermally connected to the front surface of the lower base block 24B, or the back surface of the upper base block 23B is thermally connected to the front surface of the lower base block 24B via a thermally conductive sheet 51. This configuration allows the upper outer block 23A to have an external heat dissipation function, the lower outer block 43B and the upper base block 23B to have watertightness and heat transfer functions, and the lower base block 24B to have heat removal and protection functions.

[0104] Figure 25 is a schematic cross-sectional view showing yet another example of installing an electronic device in a cooling medium composite. In the example shown in Figure 25, the cooling medium composite 1000 differs from the cooling medium composite 901 shown in Figure 24(B) in that the upper outer block 23A, lower outer block 43B, upper base block 23B, and base block 24B are wider and larger to accommodate a large semiconductor device with a heterogeneous integration structure in which multiple heat-generating elements (semiconductor chips) 33 have different surface heights, and the lower base block 24B has multiple convex surfaces of different heights on its back surface. This allows thermal connection with multiple heat-generating elements 33 to be ensured by assembling the entire assembly after appropriately processing the back surface of the lower base block without making any changes to the upper base block.

[0105] Figure 26 is a schematic cross-sectional view showing yet another example of installing an electronic device in a cooling medium composite. In the example shown in Figure 25, the cooling medium composite 2000 differs from the cooling medium composite 1000 shown in Figure 25 in that a metal frame (hereinafter referred to as a "stiffener") 38 is provided to surround multiple heat-generating elements (semiconductor chips) in a large semiconductor device with a heterogeneous integration structure, and the upper outer block 23A, lower outer block 43B, upper base block 23B, and base block 24B are wider and larger to accommodate larger semiconductor devices. In this example, the back surface of the lower base block 24B has multiple convex surfaces of different heights, and a concave surface is formed on the back surface of the lower base block 24B at a position corresponding to the stiffener 38, ensuring compatibility with a board on which a semiconductor device with a stiffener is mounted.

[0106] FIG. 27 is a schematic cross-sectional view showing yet another example of installing an electronic device in a cooling medium composite. In the example shown in FIG. 27(A), the cooling medium composite 3000 is similar to the cooling medium composite 402 shown in FIG. 19(C) in that the outer block 53A is a plate-like structure without fins. However, it differs from the cooling medium composite 402 in that an opening similar to the second opening formed in the bonding layer 41 is formed inside the outer block 53A, the outer block 53A is fixed to the base block 21B with two screws at each of its four corners, and it does not have a thermally conductive sheet. In this example, the back surface of the outer block 53A does not need to be thermally connected to the surface of the base block 21B. The outer block 53A has a watertight function but does not need to have a heat transfer function. On the other hand, a portion of the surface of the base block 21B directly comes into contact with the coolant outside the bag 11 through the second opening in the bonding layer 41, the first opening in the bag 11, and the opening in the outer block 53A. In other words, the base block 21B has the functions of removing heat from the heat generating element, protecting the heat generating element, maintaining watertightness, and dissipating heat to the outside. This example is one of the examples that includes a heat sink device with the simplest structure and made up of a minimum number of blocks.

[0107] The example shown in Figure 27(B) is a modification of the example shown in Figure 27(A). In the example shown in Figure 25, the cooling medium composite 3001 differs from the cooling medium composite 3000 shown in Figure 25 in that it has a fin region 212 on the surface side of the base block 21B, and the fin region 212 has multiple plate-shaped fins that rise up from the base portion 211. The fins in the fin region 212 are exposed from the bag 11 through the second opening in the bonding layer 41, the first opening in the bag 11, and the opening in the outer block 53A. Having multiple fins in the fin region 212 increases the heat dissipation area and enhances the external heat dissipation function. In this modification, the flat surface (surface) of the base block 21B is located inside the bag 11, and the back surface of the outer block 25, which is placed outside, and the surface of the base block 21B function to maintain a watertight seal on both sides of the area surrounding the first opening. The phrase "placed inside the non-conductive bag" should be understood to include a configuration in which the main portion (base portion) of the base block is located inside the bag and a portion of the base block (in this example, the multiple fins) is located outside the bag, as in this modified example. Conversely, the phrase "placed outside the non-conductive bag" should be understood to include a configuration in which the main portion of the outer block is located outside the bag and a portion of the outer block (e.g., the protruding portion) is located inside the bag.

[0108] Although preferred examples and modifications for mounting electronic devices in the cooling medium composite have been described above with reference to the drawings, further modifications may be made to the details of the components. For example, as already described with reference to the bonding layer, in the examples of the cooling medium composites 101, 102, 103, 600, 601, 602, 800, 801, 802, 900, 901, 902, 1000, and 2000, watertightness may be further enhanced by additionally installing double-sided adhesive tape or watertight packing between the outer surface of the non-conductive bag 11 and the back surface of the outer block 23A, or between the outer surface of the non-conductive bag 11 and the back surface of the lower outer block 43B, so as to surround the periphery of the opening of the bag 11. As another example of enhancing watertightness, minute interlocking concave and convex surfaces may be formed on the back surface of the outer block 23A and the surface of the base block 21B / 23B, so that the interlocking concave and convex surfaces can prevent the intrusion of the coolant.

[0109] Referring again to FIG. 13 , an example of operation of the cooling system 1 will be described in more detail. Two or more cooling medium composites 100 may be immersed in the coolant 4 contained in the cooling tank 3. A top plate 3A may be installed in the cooling tank 3 to reduce evaporation of the coolant 4. Furthermore, the cooling medium composite 100 of the cooling system 1 may include, in the non-conductive bag 11, a wireless power supply unit (not shown) for supplying power to the electronic device 10 instead of a power cable, and may also include, in the non-conductive bag 11, a wireless communication unit (not shown) for enabling wireless communication between the electronic device 100 and the outside instead of a network communication cable. In this case, a through hole for passing a cable and a sealant provided in the through hole are not required, thereby saving the effort required to ensure and maintain the airtightness of the through hole.

[0110] The cooling medium composite 100 of the cooling system 1 may also include a monitor unit 120 in the non-conductive bag 11 for monitoring the degree of vacuum or electrical conductivity within the non-conductive bag 11. Monitoring the conductivity within the bag to check for the presence of water or water vapor within the bag, which could cause an electrical short circuit and damage a circuit board or electronic components, is useful from the perspective of preventing electronic device failure. Furthermore, the cooling system 1 may also include a controller 160 that, when the output of the monitor unit 120 indicates a degree of vacuum below a predetermined threshold, starts an external vacuum pump 7 and controls the evacuation of the non-conductive bag 11 via an air tube 9 connected to a check valve 19. An operator may also be able to visually check the output value of the monitor unit 120 and the operating status of the controller 160 on a computer (PC) 180 communicatively connected to the controller 160. This allows the degree of vacuum to be monitored and evacuation to be performed autonomously as needed, thereby maintaining the near-vacuum sealed structure of the cooling medium composite 100 for a long period of time. Additionally or alternatively, the cooling system 1 may include a shutdown unit 140 that stops operation of the electronic device 10 and cuts off power when the output of the monitor unit 120 indicates a vacuum level below a predetermined threshold or a conductivity above a predetermined threshold. If the vacuum or watertightness of the cooling medium composite 100 is compromised, the surrounding coolant may seep into the cooling medium composite 100, causing an electrical short circuit and potentially irreversible damage to the entire electronic device 100. The shutdown unit 140 can prevent such problems from occurring by instantly stopping the operation and power supply of the electronic device 100.

[0111] Note that various modifications of the components are possible in the above-described embodiment of the cooling system. For example, instead of a zipper mechanism, the non-conductive bag may have a heat-sealing mechanism. The heat-sealing mechanism may be configured to allow an electronic device to be placed inside the non-conductive bag in an unheat-sealed state, allow vacuuming as needed after heat-sealing, and maintain the watertightness of the non-conductive bag in a heat-sealed state. When the cooling system is in operation, a portion of the heat-sealing mechanism may be left open, and the cooling medium composite may be immersed in the cooling liquid so that the heat-sealing mechanism is positioned above the liquid surface of the cooling liquid. In this way, the bag may be pressed by the hydraulic pressure of the surrounding cooling liquid, thereby expelling air from the bag to the outside and bringing the inner surface of the non-conductive bag into relatively close contact with both sides of the board and the surfaces of various electronic components mounted on the board. When two or more heating elements are mounted on the substrate of an electronic device, the size and / or number of the heat sink device, the selection of material for each block, the combination of blocks of different materials, the size and / or number of the dissimilar material bonding film, double-sided adhesive tape, or watertight packing that forms the bonding layer, the size and / or number of second openings (windows) formed in these, and the position, size, and / or number of the first openings (windows) formed in the non-conductive bag may be determined appropriately, taking into consideration the positions at which the two or more heating elements are mounted on the substrate, the sizes of the heating elements, the expected maximum heat generation, etc.

[0112] The present invention can be widely applied to cooling systems and cooling methods that efficiently cool electronic devices by immersing them in a conductive coolant such as ordinary water, tap water, or seawater.

[0113] 1 Cooling system 3 Cooling tank 3A Top plate 4 Coolant (water) 5 Piping 7 Vacuum pump 9 Air tube 10 Electronic device 100, 101, 102, 300, 301, 302, 400, 401, 402, 500, 501, 502, 600, 601, 602, 700, 701, 702, 800, 801, 802, 900, 901, 1000, 2000 Cooling medium composite 120 Vacuum degree / conductivity monitor unit 140 Shutdown unit 160 Control unit 180 Computer (PC) 11 Non-conductive bag 11A Outer surface 11B Inner surface 15 First opening 17 Sealing material 19 Check valve 20 Zipper mechanism 21 Heat sink device 21A, 23A, 43A, 43B, 53A Outer block 21B, 23B, 24B Base block 211 Base portion 212 Fin region 212B Flat portion (first back surface) 213 Elevated portion 213B Flat portion (second back surface) 215 Screw hole (through hole) 21B Base block 221 Plate-shaped member 221A Front surface 221B Back surface 225, 227 Screw hole 25, 27 Screw 28 Support screw 29 Push pin 31 Substrate (PCB) 32 Spacer 33 Heat generating element (CPU) 34 Thermal conductive grease 35 Electronic component 36 Network communication cable 37 Power cable 38 Stiffener 41 Bonding layer 43 Second opening 51 Thermal conductive sheet

Claims

1. A cooling system for cooling an electronic device by immersing it in a cooling liquid, the cooling system including a cooling medium composite, the cooling medium composite including: a non-conductive bag for encasing an electronic device including a substrate and at least one heat generating element mounted on the substrate; a heat sink device including a thermally conductive base block placed inside the non-conductive bag; and a thermally conductive outer block placed outside the non-conductive bag and fixed to the base block, the non-conductive bag having a first opening, the outer block and the base block being thermally connected through the first opening of the non-conductive bag when the outer block is fixed to the base block, the back surface of the outer block and the front surface of the base block maintaining both sides of a peripheral area of ​​the first opening of the non-conductive bag watertight, and the back surface of the base block providing a connection surface thermally connected to one side of the at least one heat generating element.

2. The cooling system of claim 1, wherein a raised portion is formed on the rear surface of the outer block or the front surface of the base block, and the raised portion contacts the front surface of the base block or the rear surface of the outer block through the first opening of the non-conductive bag.

3. The cooling system according to claim 2, wherein the first opening formed in the non-conductive bag has an opening area larger than an area of ​​the raised portion.

4. The cooling system of claim 1, wherein a thermally conductive sheet or thermally conductive grease is arranged to fill the first opening of the non-conductive bag, and the back surface of the outer block is in contact with the surface of the base block via the thermally conductive sheet or the thermally conductive grease.

5. The cooling system of claim 1, wherein the outer block includes a thermally conductive lower outer block and a thermally conductive upper outer block thermally connected to and fixed to a surface of the lower outer block, and when the lower outer block is fixed to the base block, the back surface of the lower outer block and the surface of the base block keep both sides of the surrounding area of ​​the first opening of the non-conductive bag watertight.

6. The cooling system of claim 1, wherein the base block includes a thermally conductive lower base block and a thermally conductive upper base block thermally connected to and fixed to a surface of the lower base block, and when the outer block is fixed to the upper base block, the back surface of the outer block and the surface of the upper base block keep both sides of the surrounding area of ​​the first opening of the non-conductive bag watertight.

7. The cooling system of claim 1, wherein the outer block includes a thermally conductive lower outer block and a thermally conductive upper outer block thermally connected to and fixed to a surface of the lower outer block, the base block includes a thermally conductive lower base block and a thermally conductive upper base block thermally connected to and fixed to a surface of the lower base block, and when the lower outer block is fixed to the upper base block, the back surface of the lower outer block and the surface of the upper base block keep both sides of the surrounding area of ​​the first opening of the non-conductive bag watertight.

8. A cooling system as described in claim 1, 5, 6 or 7, wherein a material used for the outer block, the upper outer block or the lower outer block is different from a material used for the base block, the upper base block or the lower base block.

9. A cooling system as described in claim 1, 5, 6 or 7, wherein a plurality of convex surfaces of different heights are formed on the rear surface of the base block or the rear surface of the lower base block, and the plurality of convex surfaces are thermally connected to a plurality of surfaces of a plurality of heating elements of different heights.

10. A cooling system as described in claim 1, 5, 6 or 7, wherein the base block or the lower base block has a substrate fixing mechanism, and the substrate of the electronic device is fixed to the substrate fixing mechanism of the base block or the lower base block.

11. The cooling system of claim 10, wherein the substrate fixing mechanism of the base block or the lower base block is two or more screw holes formed apart from one another on the rear surface of the base block or the lower base block.

12. The cooling system of claim 1, wherein the cooling medium composite further includes a bonding layer that provides a watertight connection between the back surface of the outer block and the outer surface of the non-conductive bag, or between the front surface of the base block and the inner surface of the non-conductive bag, the bonding layer being formed from a dissimilar material bonding film, a double-sided adhesive tape, or a watertight puncture, the dissimilar material bonding film, the double-sided adhesive tape, or the watertight puncture having a second opening corresponding to the first opening of the non-conductive bag, and the outer block and the base block are thermally connected through the first opening of the non-conductive bag and the second opening of the bonding layer.

13. The cooling system of claim 12, wherein a raised portion is formed on the rear surface of the outer block or the front surface of the base block, and the raised portion contacts the front surface of the base block or the rear surface of the outer block through the first opening of the non-conductive bag and the second opening of the bonding layer.

14. The cooling system of claim 13, wherein the first opening of the non-conductive bag and the second opening of the bonding layer have an open area greater than an area of ​​the raised portion.

15. The cooling system of claim 12, wherein a thermally conductive sheet or thermally conductive grease is arranged to fill the first opening of the non-conductive bag and the second opening of the bonding layer, and the back surface of the outer block is in contact with the surface of the base block via the thermally conductive sheet or the thermally conductive grease.

16. The cooling system of claim 12, wherein the outer block includes a thermally conductive lower outer block and a thermally conductive upper outer block thermally connected to and fixed to a surface of the lower outer block, and when the lower outer block is fixed to the base block, the back surface of the lower outer block and the surface of the base block keep the area surrounding the first opening of the non-conductive bag and the area surrounding the second opening of the bonding layer watertight when the lower outer block is fixed to the base block.

17. The cooling system of claim 12, wherein the base block includes a thermally conductive lower base block and a thermally conductive upper base block thermally connected to and fixed to a surface of the lower base block, and when the outer block is fixed to the upper base block, the back surface of the outer block and the surface of the upper base block keep the area surrounding the first opening of the non-conductive bag and the area surrounding the second opening of the bonding layer watertight.

18. The cooling system of claim 12, wherein the outer block includes a thermally conductive lower outer block and a thermally conductive upper outer block thermally connected to and fixed to a surface of the lower outer block, and the base block includes a thermally conductive lower base block and a thermally conductive upper base block thermally connected to and fixed to a surface of the lower base block, and when the lower outer block is fixed to the upper base block, the back surface of the lower outer block and the surface of the upper base block keep the surrounding area of ​​the first opening of the non-conductive bag and the surrounding area of ​​the second opening of the bonding layer watertight.

19. A cooling system as described in claim 12, 16, 17 or 18, wherein a plurality of convex surfaces of different heights are formed on the rear surface of the base block or the rear surface of the lower base block, and the plurality of convex surfaces are thermally connected to a plurality of surfaces of a plurality of heating elements of different heights.

20. A cooling system as described in claim 12, 16, 17 or 18, wherein the base block or the lower base block has a substrate fixing mechanism, and the substrate of the electronic device is fixed to the substrate fixing mechanism of the base block or the lower base block.

21. The cooling system of claim 20, wherein the substrate fixing mechanism of the base block or the lower base block is two or more screw holes formed apart from one another on the rear surface of the base block or the lower base block.

22. The cooling system of claim 1, wherein said heat sink device comprises a plurality of heat dissipating fins located on the exterior of said non-conductive bag.

23. The cooling system of claim 1, wherein the cooling medium composite is configured such that when the non-conductive bag is immersed in a cooling liquid, the inner surface of the non-conductive bag comes into contact with both sides of the substrate and surfaces of various electronic components mounted on the substrate by liquid pressure.

24. The cooling system of claim 1, wherein the cooling medium composite is configured such that, when a vacuum is drawn inside the non-conductive bag as necessary, the inner surface of the non-conductive bag is in intimate contact with both sides of the substrate and the surfaces of various electronic components mounted on the substrate.

25. The cooling system of claim 24, wherein the non-conductive bag is configured with a check valve that provides a path for drawing a vacuum and allows a seal to be maintained.

26. The cooling system of claim 24, wherein the non-conductive bag has a zipper mechanism configured to allow placement of the electronic device inside the non-conductive bag in a zipper open state and to maintain the non-conductive bag in a sealed state in a zipper closed state.

27. The cooling system of claim 24, wherein the non-conductive bag has a heat sealing mechanism that is configured to place the electronic device inside the non-conductive bag in an unheat-sealed state, and to achieve watertightness in the water-immersed portion after immersion in water after heat sealing, and to maintain watertightness in the heat-sealed state.

28. The cooling system of claim 24, wherein the non-conductive bag has a heat sealing mechanism configured to allow placement of the electronic device inside the non-conductive bag in an unheat-sealed state and to allow for vacuum application as necessary after heat sealing, and to maintain the airtightness of the non-conductive bag in a heat-sealed state.

29. A cooling system as described in claim 22 or 24, wherein the non-conductive bag has a through hole for passing a power cable, a network communication cable, or a control cable connected to an electronic device, and a sealant provided in the through hole is configured to maintain the watertightness or airtightness of the non-conductive bag.

30. The cooling system of claim 23 or 24, wherein the cooling medium composite further includes, within the non-conductive bag, a wireless power supply unit for supplying power to the electronic device, and a wireless communication unit for enabling wireless communication between the electronic device and the outside.

31. The cooling system of claim 23 or 24, wherein the cooling medium composite further includes a monitor unit within the non-conductive bag for monitoring the degree of vacuum or electrical conductivity within the non-conductive bag.

32. The cooling system of claim 31, further comprising an exhaust controller that controls, when the output of the monitor unit indicates a vacuum level below a predetermined threshold, to start a vacuum pump disposed outside the cooling medium composite and draw a vacuum inside the non-conductive bag.

33. The cooling system of claim 31, further comprising a shutdown unit that stops operation of the electronic device and cuts off power when the output of the monitor unit indicates a vacuum level below a predetermined threshold or indicates a conductivity level above a predetermined threshold.

34. A cooling system for cooling an electronic device by immersing it in a cooling liquid, the cooling system including a cooling medium composite, the cooling medium composite including: a non-conductive bag for encasing an electronic device including a substrate and at least one heat generating element mounted on the substrate; a heat sink device including a thermally conductive base block placed inside the non-conductive bag; and a thermally conductive outer block placed outside the non-conductive bag and fixed to the base block, the non-conductive bag having a first opening, when the outer block is fixed to the base block, a back surface of the outer block and a front surface of the base block keep both sides of a surrounding area of ​​the first opening of the non-conductive bag watertight, and the back surface of the base block provides a connection surface that is thermally connected to one side of the at least one heat generating element.

35. A method for cooling an electronic device, comprising the steps of: preparing a heat sink device including a thermally conductive base block and a thermally conductive outer block; preparing a non-conductive bag for encasing an electronic device including a substrate and at least one heat generating element mounted on the substrate, the non-conductive bag having a first opening for the heat sink device; and forming a cooling medium composite, the step of fixing the outer block placed outside the non-conductive bag to a thermally conductive base block placed inside the non-conductive bag, wherein when the outer block is fixed to the base block, the outer block is thermally connected to the base block through the opening formed in the non-conductive bag, and the back surface of the outer block and the front surface of the base block keep both sides of the surrounding area of ​​the first opening of the non-conductive bag watertight; The method includes the steps of placing the electronic device within the cooling medium composite and fixing the base block to the substrate so that one surface of the at least one heat generating element is in surface contact with and thermally connected to a back surface of the base block; at least partially water-tightening the non-conductive bag; and immersing the at least partially water-tight portion of the cooling medium composite in a cooling liquid.

36. A method for cooling an electronic device, comprising the steps of: preparing a heat sink device including a thermally conductive base block and a thermally conductive outer block; preparing a non-conductive bag for enclosing an electronic device including a substrate and at least one heat generating element mounted on the substrate, the non-conductive bag having a first opening for the heat sink device; fixing the base block to the substrate such that one surface of the at least one heat generating element is in surface contact with and thermally connected to a back surface of the base block of the heat sink device; and forming a cooling medium composite, the steps of: placing the electronic device with the base block in the non-conductive bag; and fixing the outer block, which is placed outside the non-conductive bag, to the base block, wherein when the outer block is fixed to the base block, the outer block is thermally connected to the base block through the first opening formed in the non-conductive bag, and the back surface of the outer block and the front surface of the base block keep both sides of the surrounding area of ​​the opening of the non-conductive bag watertight. constructing the cooling media composite; at least partially watertightening the non-conductive bag; and immersing the at least partially watertight portion of the cooling media composite in a cooling liquid.

37. A method for cooling an electronic device, comprising the steps of: preparing a heat sink device including a thermally conductive base block and a thermally conductive outer block; preparing a non-conductive bag for enclosing an electronic device including a substrate and at least one heat generating element mounted on the substrate, the non-conductive bag having a first opening for the heat sink device; constructing a cooling medium composite, the step of fixing the outer block placed outside the non-conductive bag to a thermally conductive base block placed inside the non-conductive bag, characterized in that when the outer block is fixed to the base block, the back surface of the outer block and the front surface of the base block keep both sides of the surrounding area of ​​the first opening of the non-conductive bag watertight; placing the electronic device in the cooling medium composite, and fixing the base block to the substrate such that one surface of the at least one heat generating element is in surface contact with and thermally connected to the back surface of the base block; and making the non-conductive bag at least partially watertight. and c) immersing the at least partially watertight portion of the cooling media composite in a cooling fluid.

38. A method for cooling an electronic device, comprising the steps of: preparing a heat sink device including a thermally conductive base block and a thermally conductive outer block; preparing a non-conductive bag for enclosing an electronic device including a substrate and at least one heat generating element mounted on the substrate, the non-conductive bag having a first opening for the heat sink device; fixing the base block to the substrate such that one surface of the at least one heat generating element is in surface contact with and thermally connected to a back surface of the base block of the heat sink device; and forming a cooling medium composite, the steps being: placing the electronic device with the base block in the non-conductive bag; and fixing the outer block, which is placed outside the non-conductive bag, to the base block, characterized in that when the outer block is fixed to the base block, the back surface of the outer block and the front surface of the base block keep both sides of the surrounding area of ​​the opening of the non-conductive bag watertight. The steps of forming the cooling medium composite; and at least partially making the non-conductive bag watertight. and c) immersing the at least partially watertight portion of the cooling media composite in a cooling fluid.

39. A method according to any one of claims 35 to 38, wherein the step of fixing the outer block to the base block includes a step of bonding between the back surface of the outer block and the outer surface of the non-conductive bag, or between the front surface of the base block and the inner surface of the non-conductive bag, using a dissimilar material bonding film, double-sided adhesive tape, or watertight packing.

40. The method of any one of claims 35 to 38, wherein the step of making the non-conductive bag at least partially watertight comprises drawing a vacuum within the non-conductive bag.

41. A method according to any one of claims 35 to 38, wherein the step of making the non-conductive bag at least partially water-tight includes performing the step of immersing the cooling medium composite in a cooling liquid, in which when at least a portion of the non-conductive bag is immersed in the cooling liquid, the inner surface of the portion of the non-conductive bag is brought into contact with both sides of the substrate and surfaces of various electronic components mounted on the substrate by the hydraulic pressure of the cooling liquid.

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