JP7651699B2 - Heat sink for cooling thermal devices - Google Patents

Description

The present invention relates to a heat sink for cooling thermal devices.

Semiconductor devices, particularly power semiconductors, generate a large amount of heat during operation, and in order to ensure stable operation, the temperature rise is suppressed by dissipating the heat via a heat sink, for example. This heat sink is composed of a base member made of a metal member and plate-shaped fins arranged side by side at regular intervals on the surface of the base member. Since gaps (flow paths) are formed between adjacent fins, a fluid such as air can pass through the grooves, thereby efficiently cooling the semiconductor devices and other devices placed on the base member.

Patent Document 1 describes a heat pipe and cooler that can increase the efficiency of heat transport by providing multiple holes arranged parallel to the longitudinal direction inside the heat pipe, solving the problem of installation space limitations, and efficiently transporting heat in a minimum of space to cool a heat-generating body.

Furthermore, Patent Document 2 describes a heat pipe having a container with multiple cross-sectional shapes along the longitudinal direction, a working fluid sealed inside the container, and a wick structure formed on the inner wall surface of the container that is installed inside the container and transports the working fluid by capillary force.

Furthermore, Patent Document 3 describes a heat transport device that includes a heat pipe filled with a working fluid, a heat receiving plate at one end of the heat pipe, and a heat dissipation fin at the other end, in which the heat pipe has a first wick and a second wick that transport the working fluid on its inner wall surface, a bent portion between the one end and the other end, and the boundary between the first wick and the second wick is located at the bent portion of the heat pipe or at the lower portion of the heat transport device in the direction of gravity, thereby improving the heat transport characteristics.

Patent Document 4 also describes a heat pipe equipped with a wick structure in a flat container having flat inner surfaces that face each other in the vertical direction in a cross section perpendicular to the longitudinal direction, the wick structure being composed of a first wick structure and a second wick structure arranged in the vertical direction, the first wick structure being in contact with one of the flat inner surfaces and the second wick structure, respectively, and both side surfaces of the first wick structure being not in contact with any of the inner surfaces of the flat container, the second wick structure being in contact with the other of the flat inner surfaces, and both side surfaces of the second wick structure being not in contact with any of the inner surfaces of the flat container, and further, the wick structures being arranged side by side in the longitudinal direction of the flat container.

Furthermore, Patent Document 5 describes a thin heat pipe structure that improves thermal conduction efficiency, comprising a main body having a flat cross-sectional structure and a chamber having a first surface in contact with a heat source and a second surface that serves as a heat dissipation surface.

JP 2010-133686 A JP 2013-195001 A JP 2015-161448 A International Publication No. 2017/115771 Utility Model Registration No. 3175221

In recent years, there has been an increasing demand for higher performance and smaller size of semiconductor devices, including power semiconductors. To achieve this, the performance of semiconductor elements needs to be improved, but as performance improves, the amount of heat generated increases. In addition, it is necessary to increase the density of semiconductor elements arranged in semiconductor devices, and the denser the semiconductor elements are arranged, the greater the amount of heat generated. In order to deal with the dramatically increasing amount of heat generated, there is a strong demand for improved cooling performance of heat sinks. Furthermore, there is also a demand for the miniaturization of the heat sink itself.
An object of the present invention is to provide a heat sink that is easy to miniaturize and has high cooling performance, and is used for cooling thermal devices such as semiconductors, and is particularly suitable for cooling thermal devices such as semiconductors used in small modules, etc.

After extensive research, the inventors discovered that the above problems could be solved by a heat sink for cooling thermal devices, which is a cylindrical metal heat sink having heat dissipation fins on at least a portion of its outer periphery and has a connecting portion with other metal heat sinks, and thus completed the present invention.

That is, the present invention relates to the following (1) to (6).
(1) A metal heat sink for cooling thermal devices, characterized in that it has two or more cylindrical sections in which thermal devices or the like are placed, and that the cylindrical sections are provided with heat dissipation fins on the outer periphery.
With this configuration, a plurality of thermal devices can be cooled by a single heat sink, so that the thermal devices can be cooled efficiently and the space required can be reduced.
(2) The heat sink according to (1), characterized in that at least one pair of cylindrical portions are joined by heat dissipation fins.
With this configuration, by joining the cylindrical portion with the heat dissipation fins, the surface area of the heat dissipation fins can be increased, improving the performance of the heat sink.
(3) A metal heat sink for cooling a thermal device according to (1), characterized in that at least one pair of cylindrical parts are directly joined to each other.
With this configuration, the cylindrical portions are joined together, so that they can be joined firmly, and the joining strength is improved.
(4) A metal heat sink for cooling a thermal device according to any one of (1) to (3), characterized in that the cylindrical portion and the heat dissipation fin portion are made of aluminum (including alloys) and are integrally formed by an extrusion process.
By processing aluminum using the extrusion method, it is possible to easily manufacture complex cross-sectional shapes. Therefore, the cylindrical portion and the fins can be easily molded as a single unit. By molding them as a single unit, the number of joints can be reduced, improving the cooling performance of the heat sink.
(5) The metallic heat sink for cooling a thermal device according to (4), which is formed by joining a plurality of aluminum extrusions.
By processing aluminum using the extrusion method, it is possible to easily manufacture complex cross-sectional shapes. Therefore, the cylindrical portion and the fins can be easily molded as a single unit, which reduces the number of joints between the components of the heat sink and reduces the thermal contact resistance between the components, improving the performance of the heat sink.
(6) The metallic heat sink for cooling a thermal device according to any one of (1) to (5), characterized in that the cylindrical portion is provided with a heat source, a heat spreader, or a heat pipe inside.

According to the present invention, it is possible to provide a heat sink that is used for cooling thermal devices such as power semiconductors, and is particularly suitable for cooling thermal devices such as semiconductors used in high-performance small modules.

1 is a diagram showing an example of a heat sink for cooling a thermal device according to the present invention, which is a type in which cylindrical portions are directly joined to each other. 1 is a diagram showing an example of a heat sink for cooling a thermal device according to the present invention, which is a type in which a cylindrical member is joined via cooling fins. FIG. 2 is a diagram showing an example of an extrusion material forming an aluminum heat sink of the present invention. FIG. 2 is a diagram showing an example of an extrusion material forming an aluminum heat sink of the present invention.

One embodiment of the present invention is described in detail below. The present invention is not limited to the following embodiment, and can be implemented with appropriate modifications within the scope that does not impair the effects of the present invention.

[Heat sink for cooling thermal devices]
As shown in FIG. 1a and FIG. 1b, the heat sink for cooling a thermal device according to the present embodiment has two or more cylindrical parts in which a thermal device or the like is arranged, and a heat dissipation fin is provided on the outer periphery of the cylindrical part. The fins are arranged in parallel at approximately equal intervals. In addition, a gap is formed between adjacent fins. The gap is a part that becomes a flow path through which a fluid for cooling the fins of the heat sink for cooling a thermal device flows. The cross-sectional shape of the cylindrical part is preferably close to the shape and size of the thermal device or the like arranged so that the thermal device is in close contact with the inside of the cylindrical part. Depending on the shape of the thermal device, it is not limited to a square, and may be a circle (when the thermal device is a heat pipe, etc.). In addition, the shape and size of the cylindrical parts do not need to be the same. If the cylindrical parts are directly joined together as shown in FIG. 1a, the joining area can be increased, and the strength of the heat sink is improved. If the cylindrical parts are joined by cooling fins as shown in FIG. 1b, the surface area of the cooling fins can be increased, and the cooling performance is improved. In addition, in one heat sink, there may be portions where the cylindrical members are directly joined to each other, and portions where the cylindrical members are joined to each other by fins.

The cylindrical portion may be integrally molded by extrusion processing, or cut out from a metal block. Alternatively, separately manufactured components may be joined by known joining methods such as bolts, fitting, brazing, or conductive adhesives. There are no particular limitations on the size of the cylindrical metal heat sink, but an example would be one that is 5-9 cm long, 3-7 cm wide, and 6-10 cm high.

The metal members constituting the cylindrical metal heat sink are not particularly limited, and may be aluminum, aluminum alloy, copper, copper alloy, titanium, titanium alloy, magnesium, magnesium alloy, etc. The cylindrical metal heat sink and the fins may be made of different materials, but aluminum has excellent thermal conductivity and is lightweight, and can easily be formed into complex cross-sectional shapes by extrusion processing, so the metal members are preferably aluminum or aluminum alloys. Among them, if you want to further improve the cooling performance of the heat sink, JIS 1000 series aluminum (e.g. 1070, etc.) is preferable. If you want strength, JIS 6000 series aluminum alloy (e.g. 6063, etc.) is preferable.

In addition, the shapes of the cylindrical parts of the connected heat sinks do not need to be the same, and for example, a heat sink with a rectangular cylindrical part and a heat sink with a triangular cylindrical part may be combined. Depending on the shape of the semiconductor module, heat sinks of several shapes may be connected.
The thermal device and the like disposed inside the cylindrical portion are fixed in close contact with the inner wall surface of the cylindrical portion by means of bolts, conductive adhesive, brazing, or the like.

The heat sink of the present invention is preferably formed from an extruded material of aluminum (including alloys). Aluminum has excellent workability, and it is possible to easily manufacture even complex cross-sectional shapes using an extrusion process.

It is possible to mold the heat sink as a single unit using aluminum extrusion material, but it may also be possible to extrude several parts and then join them using bolts, brazing, conductive adhesives, fitting methods, etc. to form the shape of the heat sink. This allows the number of extrusion dies to be reduced.

The heat dissipation fins are plate-shaped metal members that are rectangular in plan view, and multiple pieces are arranged at approximately equal intervals on the outer periphery of the cylindrical portion. The height, thickness, dimensions, number of fins, etc. are not particularly limited and can be set appropriately depending on the application. In this embodiment, the outer periphery of the cylindrical portion refers to the outer periphery of the cylindrical portion and its vicinity. By providing the heat dissipation fins on the outer periphery of the cylindrical portion, heat is dissipated from the heat dissipation fins, effectively cooling the cylindrical portion.

The heat dissipation fins may be made of aluminum, aluminum alloys, copper, copper alloys, titanium, titanium alloys, magnesium, magnesium alloys, etc., with aluminum and aluminum alloys being particularly preferred. It is also preferable to use the same material as the cylindrical portion.

The heat dissipation fins may be integrally formed with the tubular portion, may be formed by groove cutting, or may be joined to the tubular portion by brazing, but it is preferable that they are integrally formed with the tubular portion.

In one embodiment, the heat dissipation fins are arranged parallel to the axial direction of the tubular portion, making it possible to integrally mold the tubular portion and the heat dissipation fins by extrusion molding.

The heat dissipation fins do not necessarily need to cover the entire outer circumference of the tubular member as long as they provide a certain level of cooling effect, but it is preferable for them to cover at least half of the outer circumference, and it is even more preferable for them to cover at least three-quarters of the outer circumference.

Furthermore, in the heat sink for cooling a thermal device of the present invention, it is preferable that the inside of the cylindrical portion is provided with a heat source, a heat spreader, or a heat pipe. It is preferable that these are closely fixed to the inner wall surface of the cylindrical portion by bolting, using a conductive adhesive, brazing, or the like.

A heat spreader is a structure that is inserted between a heat generating element and a radiator to promote the transfer of heat and increase the heat dissipation efficiency. For example, a metal plate with high thermal conductivity such as copper or carbon can be used as a heat spreader. There are no particular limitations on the size or shape, and it can be selected appropriately according to the shape of the thermal device or cylindrical part to be installed. By providing a heat generating element such as a thermal device at one end of the heat spreader and the heat sink of the present invention at the other end, the heat from the heat generating element transferred from the heat spreader to the heat sink is efficiently dissipated.

A heat pipe is a device for cooling by utilizing the latent heat generated when a working fluid evaporates, and includes a container, a working fluid sealed in the container, and a wick. The container may be made of aluminum, aluminum alloy, copper, copper alloy, titanium, titanium alloy, magnesium, magnesium alloy, or the like. The working fluid may be water, alcohol, ammonia, or a fluorocarbon-based refrigerant. The wick may be a porous structure formed by sintering metal powder. One end of the heat pipe functions as an evaporator, and the other end functions as a condenser. In the evaporator, the working fluid evaporates by receiving heat, and the gasified working fluid moves to the condenser. In the condenser, the working fluid releases heat and condenses. The condensed working fluid moves through the wick and flows back to the evaporator.
By providing the heat sink of the present invention on the outside of the condensation section of the heat pipe, the heat emitted from the condensation section can be efficiently dissipated.

The shape of the heat pipe is not particularly limited, and may be a prism, polyhedron, etc., and may be appropriately selected according to the shape of the thermal device and the cylindrical part to be installed. In this embodiment, the heat pipe is designed so that the thermal device can be installed, and may be structured so that the thermal device is in contact with both the cylindrical part and the heat pipe. Heat generated in the thermal device is transferred to both the cylindrical part and the heat pipe, and the thermal device is effectively cooled. In addition, the use of a heat pipe eliminates the need for a fluid passage, making the structure simpler and simplifying the installation work. In some embodiments, it is also possible to install multiple thermal devices in the heat sink.

A heat sink for cooling a thermal device according to an embodiment of the present invention may have three cylindrical portions as shown in FIG. 2a, or may have four or five cylindrical portions.
2b, a part of the cylindrical part may be manufactured as a separate member, in which case the respective members of the cylindrical part may be joined after the thermal device is disposed, making it easier to dispose the thermal device.

Although the present invention has been described above using various embodiments, it goes without saying that the technical scope of the present invention is not limited to the scope described in the above embodiments. It is clear to those skilled in the art that various modifications and improvements can be made to the above embodiments. Furthermore, it is clear from the description of the claims that forms incorporating such modifications or improvements can also be included in the technical scope of the present invention.

The heat sink of this embodiment is easy to miniaturize and has high cooling performance, and therefore has industrial applicability, particularly for cooling thermal devices such as semiconductors used in small modules.

1 Heat sink 2 Cylindrical part 3 Heat dissipation fin 4 Thermal device or heat pipe or heat spreader

Claims (6)

A metal heat sink for cooling thermal devices, characterized in that it has two or more cylindrical sections inside which a thermal device is placed, and that heat dissipation fins are provided on the outer periphery of the cylindrical sections, covering at least half of the outer periphery . The metal heat sink for cooling thermal devices according to claim 1, characterized in that at least one pair of cylindrical parts is joined by heat dissipation fins. The metal heat sink for cooling thermal devices according to claim 1, characterized in that at least one pair of cylindrical parts are directly joined to each other. The metal heat sink for cooling thermal devices according to any one of claims 1 to 3, characterized in that the cylindrical portion and the heat dissipation fin portion are made of aluminum (including alloys) and are integrally molded by an extrusion process. The metal heat sink for cooling thermal devices according to claim 4, characterized in that it is formed by joining multiple aluminum extrusions. The metal heat sink for cooling thermal devices according to any one of claims 1 to 3, characterized in that the inside of the cylindrical portion is provided with a heat source, a heat spreader, or a heat pipe.

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