JP7660367B2 - Cooling structure and electronic device - Google Patents

Description

The present invention relates to a cooling structure for cooling heat-generating bodies such as electronic components arranged on a substrate, and to electronic devices using the same.

Many electronic devices have electronic circuits in which electronic components are mounted on a printed wiring board (PWB). Electronic components such as integrated circuits, transistors, diodes, resistors, and capacitors are soldered onto the PWB, which has wiring formed by lithography, to form a printed circuit board (PCB). Some electronic components generate heat during operation and are therefore used in conjunction with a cooling structure to dissipate the heat.

Heat sinks, heat pipes, etc. are often used as cooling structures. Also, because heat dissipation to the board is insufficient for cooling, a method is also used in which the housing that houses the electronic components is used for heat dissipation. In general, heat sinks, housings, and other heat dissipation parts that dissipate heat generated by electronic components to the outside are attached to each heat-generating component, such as an integrated circuit, via a heat dissipation member such as a metal plate or metal block.

In recent years, the amount of information processed by electronic devices has increased, and the amount of heat generated by electronic components has also been on the rise. This has created a demand for cooling structures that can efficiently cool electronic components. Heat dissipation members that thermally connect electronic components to heat dissipation sections can cause problems by interfering with other electronic components, so improvements to the cooling structure are being considered.

Patent Document 1 describes a sealed electronic device that includes a heat-generating component, a housing, and a heat-dissipating member (heat-dissipating section). The heat-dissipating member is formed so that its contact area with the housing is larger than its contact area with the heat-generating component. The sides of the heat-dissipating member are tapered sections that gradually widen from the heat-generating component to the housing and are formed in a tapered shape.

JP 2009-152362 A

Conventionally, heat dissipation units that dissipate heat generated by electronic components to the outside have been attached to heat-generating components via heat dissipation members such as metal plates or metal blocks, but rectangular heat dissipation members have the problem that they tend to interfere with other electronic components arranged around the heat-generating components. When they interfere with other electronic components, the size of the heat dissipation member cannot be increased, and the cross-sectional area of the heat transfer path cannot be increased, making it difficult to dissipate heat sufficiently.

As described in Patent Document 1, by providing a heat dissipation member in a tapered shape, it is possible to avoid interference with other electronic components while ensuring the cross-sectional area of the heat transfer path. However, when providing a heat dissipation member in a tapered shape, the problem is that the processing costs increase. Copper, as described in Patent Document 1, is not easy to cut, making it difficult to realize a low-cost cooling structure.

In addition, printed circuit boards may be mounted with not only integrated circuits that generate heat, but also other tall electronic components. If such electronic components do not generate heat, there is no need for the heat dissipation member to come into contact with them, but there is a risk that interference cannot be avoided if the heat dissipation member is provided in a tapered shape. In such cases, the circuit layout may be restricted or the board may need to be made larger. In particular, for integrated circuits that consume more than 10 W of power, a heat transfer member is required to cover most of the circuit board, and interference between components becomes a major problem.

In addition, multiple heat-generating components to be cooled may be placed close together on a printed circuit board. In general, it is said that a heat transfer path that spreads outward in a vertically upward direction is preferable. However, when using a tapered heat dissipation member, it is difficult to ensure such a heat transfer path for each heat-generating component.

The present invention aims to provide a cooling structure that can efficiently cool heat generating elements arranged on a substrate at low cost while avoiding interference with the surroundings, and can also efficiently cool multiple heat generating elements, as well as an electronic device that uses the same.

In other words, in order to solve the above-mentioned problems, the cooling structure of the present invention comprises a substrate on which a heat-generating element is arranged, a heat dissipation section arranged opposite the substrate and dissipating the heat generated by the heat-generating element to the outside, a plurality of heat transfer blocks for thermally conducting the heat generated by the heat-generating element toward the heat dissipation section, and a heat transfer elastic body having elasticity for thermally conducting the heat generated by the heat-generating element toward the heat dissipation section, wherein the heat transfer blocks are each provided as a columnar body which is a rectangular prism, cube, rhombic cylinder or cylinder, are stacked on top of each other in a direction perpendicular to the substrate, and are arranged between the heat-generating element and the heat dissipation section, and the heat transfer elastic body is arranged between the heat transfer blocks and the heat dissipation section.

In addition, the electronic device of the present invention comprises a substrate on which electronic components are arranged, a heat dissipation section arranged opposite the substrate and dissipating heat generated by the electronic components to the outside, a plurality of heat transfer blocks for thermally conducting the heat generated by the electronic components toward the heat dissipation section, and a heat transfer elastic body having elasticity for thermally conducting the heat generated by the electronic components toward the heat dissipation section, wherein the heat transfer blocks are each provided as a columnar body that is a rectangular prism, cube, rhombic prism or cylinder, are stacked on top of each other in a direction perpendicular to the substrate, and are arranged between the electronic components and the heat dissipation section, and the heat transfer elastic body has a cooling structure arranged between the heat transfer blocks and the heat dissipation section.

The present invention provides a cooling structure that can efficiently cool heat generating elements arranged on a substrate at low cost while avoiding interference with the surroundings, and can also efficiently cool multiple heat generating elements, as well as electronic devices that use the same.

1 is a cross-sectional view of a printed circuit board illustrating an example of a cooling structure according to an embodiment of the present invention. 1 is a cross-sectional view of a printed circuit board showing a cooling structure according to a comparative example. 1 is a cross-sectional view of a printed circuit board illustrating an example of a cooling structure according to an embodiment of the present invention. 1 is a cross-sectional view of a printed circuit board illustrating an example of a cooling structure according to an embodiment of the present invention. 1 is a diagram showing a cooling structure according to a first embodiment of the present invention; FIG. 4 is a diagram showing a cooling structure according to a first comparative example. FIG. 11 is a diagram showing a cooling structure according to a second comparative example.

The following describes a cooling structure according to one embodiment of the present invention, and an electronic device using the same, with reference to the drawings. Note that in the following drawings, common configurations are given the same reference numerals and duplicated descriptions are omitted.

FIG. 1 is a cross-sectional view of a printed circuit board showing an example of a cooling structure according to an embodiment of the present invention.
As shown in FIG. 1, the cooling structure according to this embodiment includes a substrate 1, a housing 2 that houses the substrate 1, electronic components 3 and 4 arranged on the substrate 1, and heat dissipation members 5 and 6 that conduct heat generated by the electronic components toward the housing 2.

In the cooling structure shown in FIG. 1, the electronic components 3 and 4 arranged on the board 1 include heat-generating components 3 that generate heat during operation and are subject to cooling, and non-cooling components 4 that do not substantially generate heat requiring cooling and are not subject to cooling.

In addition, in the cooling structure shown in FIG. 1, the heat dissipation members 5, 6 are a heat transfer block 5 of a simple shape made of a material with high thermal conductivity, and a thin-layer heat transfer material 6 made of a material with high thermal conductivity, which are arranged between the heat-generating component 3 and the housing 2.

The housing 2 has a hollow structure, and the ceiling surface is disposed opposite the substrate 1. In the cooling structure shown in FIG. 1, the housing 2 functions as a heat dissipation section that dissipates heat generated by the heat-generating component 3 to the outside.

Figure 1 shows a printed circuit board on which a heat-generating component 3 is arranged, as an example of a cooling structure for cooling a heat-generating element arranged on a board. The cooling structure shown in Figure 1 is structured so that heat generated by the heat-generating component (heat-generating element) 3, which is an electronic component, is transferred to the housing 2 via heat dissipation members 5 and 6, and dissipated from the housing 2 to the outside.

In the cooling structure shown in FIG. 1, the heat transfer path to the housing 2, which functions as a heat dissipation section, is formed by a heat transfer block 5 and a heat transfer material 6. The main feature of the cooling structure shown in FIG. 1 is that the heat transfer blocks 5, which are provided in a simple shape, are stacked on top of each other in a direction perpendicular to the heat-generating component 3, i.e., in a direction perpendicular to the substrate 1.

Substrate 1 is a printed wiring board with wiring formed thereon, and electronic components 3 and 4 are soldered to its surface. A printed wiring board is obtained, for example, by impregnating an insulating material such as paper or glass with a resin such as epoxy resin or bakelite, and then patterning the desired wiring by lithography.

In addition to the substrate 1, the housing 2 also houses electronic components 3 and 4 and heat dissipation members 5 and 6. In the cooling structure shown in FIG. 1, the housing 2 functions as a heat dissipation section that dissipates heat generated by the heat-generating component 3 to the outside, but from the perspective of more efficient heat dissipation, other heat dissipation mechanisms can also be thermally connected to the housing 2. Examples of other heat dissipation mechanisms include a ventilation fan and a heat sink structure.

The heat-generating component 3 is an electronic component that generates heat that requires cooling during operation, and is the target of cooling using the heat dissipation members 5, 6. The heat-generating component 3 is in contact with the heat dissipation members 5, 6, and is thermally connected to the housing 2 via the heat dissipation members 5, 6. The type, number, size, and height of the heat-generating component 3 are not particularly limited, so long as it generates heat that requires cooling. Specific examples of the heat-generating component 3 include integrated circuits such as LSIs (Large Scale Integrated circuits).

The non-cooled components 4 are electronic components that do not substantially generate heat that requires cooling. The non-cooled components 4 are non-heat generating bodies that are not subject to cooling using the heat dissipation members 5 and 6, and therefore do not need to be thermally connected to the housing 2. The non-cooled components 4 are not particularly limited in terms of type, number, size, or height.

In FIG. 1, on the substrate 1, tall components (tall bodies) that are taller than the heat-generating component 3 are arranged as non-cooled components 4 around the heat-generating component 3. The heat dissipation members 5 and 6 are thermally connected to the heat-generating component 3 and the housing 2, but must be arranged so as not to interfere with such tall components. A specific example of a tall component is a capacitor.

The heat transfer block 5 is a member for conducting heat generated by the heat generating component 3, which is a heat generating body, toward the heat dissipation section, and is formed in a block shape from a material with high thermal conductivity. Multiple heat transfer blocks 5 are arranged between the heat generating component 3 and the housing 2. Multiple heat transfer blocks 5 are stacked on top of each other in a direction perpendicular to the main surface of the heat generating component 3, i.e., along the normal direction perpendicular to the substrate 1.

The heat transfer material 6 is a member for conducting heat generated by the heat generating component 3, which is a heat generating body, toward the heat dissipation section, and is formed in a thin layer using a material with high thermal conductivity. The heat transfer material 6 is disposed between the substrate 1 and the housing 2, between the heat transfer blocks 5, between the heat transfer block 5 and the substrate 1, and between the heat transfer block 5 and the housing 2.

The heat transfer material 6 may be a heat transfer sheet in which a material with high thermal conductivity is formed into a sheet, a heat transfer grease in which a material with high thermal conductivity is mixed with a lubricant such as silicone, or a heat transfer paste in which a material with high thermal conductivity is mixed with a binder or the like. One type of heat transfer material 6 may be used between each member, or multiple types may be used in combination.

FIG. 2 is a cross-sectional view of a printed circuit board showing a cooling structure according to a comparative example.
As shown in Fig. 2, the conventional general cooling structure (comparative example) includes a substrate 1, a housing 2, and electronic components 3 and 4, similar to the cooling structure shown in Fig. 1. However, the conventional general cooling structure differs from the cooling structure shown in Fig. 1 in the configuration of heat dissipation members 51 and 61.

In the cooling structure shown in FIG. 2, the electronic components 3 and 4 are a heat-generating component 3 and a non-cooled component 4, which are arranged on the substrate 1. The heat dissipation members 51 and 61 are a heat transfer block 51 made of a material with high thermal conductivity and a thin-layer heat transfer material 61 made of a material with high thermal conductivity, which are arranged between the heat-generating component 3 and the housing 2.

In the cooling structure shown in FIG. 2, a single heat transfer block 51 in a rectangular parallelepiped shape is used as a heat dissipation member that thermally connects the heat-generating component 3 and the housing 2. Conventional cooling structures do not have multiple heat transfer blocks 51 stacked on top of each other. In this type of cooling structure, heat diffusion by thermal conduction proceeds only in approximately one direction perpendicular to the substrate 1, as shown by the arrow in FIG. 2.

In the cooling structure shown in FIG. 2, the cross-sectional area of the heat transfer path is determined by the cross-sectional area of one heat transfer block 51, so it is difficult to achieve a large amount of heat dissipation under a certain heat flux. If one heat transfer block 51 is tapered as in Patent Document 1, the cross-sectional area of the heat transfer path increases toward the housing 2, but this increases processing costs and there is a risk of interference with tall parts when they are placed around the heat-generating part 3.

In contrast, the cooling structure shown in FIG. 1 has multiple heat transfer blocks 5 stacked on top of each other, so when a small heat transfer block 5 is used at the height of a tall component and a large heat transfer block 5 is used above it, a heat transfer path with a sufficiently expanded cross-sectional area is formed without interfering with the tall component. As a result, unlike the conventional case where a single heat dissipation member is used, part of the stacked heat transfer blocks 5 with a simple shape is positioned above the tall component. With this structure, as shown by the arrows in FIG. 1, heat is diffused by thermal conduction not only in the direction perpendicular to the substrate 1, but also in the direction parallel to the substrate 1. Therefore, the cross-sectional area of the heat transfer path can be expanded while avoiding interference with the tall component, allowing for efficient heat dissipation.

The heat transfer blocks 5 may be stacked in other directions as long as they are stacked at least in a direction perpendicular to the substrate 1 for each heat-generating component 3 to be cooled. For example, another heat transfer block 5 may be stacked in a direction parallel to the substrate 1, such as front to back or left to right (front, back, left, right, etc. in FIG. 1), in addition to the heat transfer blocks 5 stacked one above the other.

As shown in FIG. 1, the multiple heat transfer blocks 5 are preferably stacked so that the cross-sectional area of the heat transfer blocks 5 increases from the heat generating component 3 toward the housing 2. In addition, it is preferable to arrange the heat transfer blocks 5 so that the contact areas between the components have a similar relationship. That is, the heat transfer blocks 5 may have a cross-sectional area equal to that of the heat generating component 3, or a cross-sectional area larger than that of the heat generating component 3. In this case, it is preferable to stack the heat transfer blocks 5 so that the cross-sectional area of the heat transfer blocks 5 and the contact areas between the components increase the closer they are to the housing 2.

With a structure in which the cross-sectional area of the heat transfer block 5 and the contact area between components increase the closer to the housing 2, even if the heat transfer block 5 on the heat-generating component 3 side is made smaller, the cross-sectional area of the heat transfer path always increases the closer to the housing 2 side. This allows efficient heat dissipation while avoiding interference with tall components. Because the area on the housing 2 side is occupied by the heat transfer block 5 rather than space, the amount of heat dissipation can be ensured by solid thermal conduction.

The heat transfer block 5 is preferably provided as a columnar body. Note that a columnar body refers to a solid body whose upper and lower surfaces are parallel to each other and have similar shapes. Specific examples of columnar bodies include rectangular parallelepipeds, cubes, rhomboidal columns, and cylinders. The heat transfer block 5 is preferably composed only of columnar bodies, and is particularly preferably composed only of rectangular parallelepipeds or cubes.

Making the heat transfer block 5 a columnar body makes it easier to process and manufacture, and therefore the cost of the heat transfer block 5 can be reduced. Because the columnar body has a simple shape, it can be used as the heat transfer block 5 after cutting out extruded material, forged material, ingots, etc., without significant secondary processing. In order to avoid interference with tall parts, secondary processing into a complex shape by cutting or the like is not required, so an efficient cooling structure can be realized at low cost.

In addition, if the heat transfer block 5 is a columnar body, the components are more likely to come into contact with each other when stacked on the heat-generating component 3. This makes it easier to form a heat transfer path with high heat dissipation efficiency. In addition, if the heat transfer block 5 is a columnar body, simply increasing the size of the heat transfer block 5 increases the cross-sectional area of the heat transfer path, resulting in a cooling structure with high heat dissipation efficiency.

The heat transfer block 5 is preferably made of a metal with high thermal conductivity such as aluminum, copper, or silver, and is particularly preferably made of an aluminum alloy. Aluminum alloys provide high thermal conductivity as well as high mechanical strength and workability. This results in a stable structure, and makes it possible to realize an efficient cooling structure at low cost.

When the heat transfer block 5 is made of an aluminum alloy, it is preferable to subject it to anodizing treatment. In general, copper is an example of a material that has excellent thermal conductivity, strength, corrosion resistance, etc. However, copper may corrode in the presence of sulfur components such as hydrogen sulfide or in an oxidizing environment. In contrast, anodizing treatment produces an aluminum block with excellent corrosion resistance and an anodized film on the surface, resulting in a cooling structure that is more resistant to corrosion than copper.

As the heat transfer material 6, it is preferable to use at least a heat transfer elastomer having elasticity. The heat transfer elastomer may be disposed in one or more of the following locations: between the heat transfer blocks 5, between the heat transfer block 5 and the substrate 1, and between the heat transfer block 5 and the housing 2. As the heat transfer elastomer, a heat transfer sheet, a heat transfer paste, or the like having elasticity to the extent that it deforms under the weight of the heat transfer block 5 at room temperature can be used.

By arranging the heat transfer elastic body in at least one location, even if there is a possibility of gaps occurring between the heat transfer blocks 5, between the heat transfer block 5 and the substrate 1, or between the heat transfer block 5 and the housing 2 due to dimensional errors, assembly, shock/vibration, etc., it is possible to eliminate the gaps through elastic deformation. Therefore, even in a structure in which multiple heat transfer blocks 5 are stacked, which is disadvantageous in terms of ensuring a heat transfer path, it is possible to efficiently dissipate heat.

Any suitable method can be used to fix the stacked heat transfer blocks 5. The heat transfer blocks 5 can be joined to each other using, for example, screws, bolts and nuts, brackets, corner braces, adhesives, etc. between the heat transfer blocks 5 themselves, between the heat transfer blocks 5 and the substrate 1, and between the heat transfer blocks 5 and the housing 2. With these joining methods, it is not necessary to perform major secondary processing on the heat transfer blocks 5 themselves, so that a cooling structure can be realized at low cost.

In FIG. 1, the housing 2 is shown as a sealed type, but it may be a non-sealed type. The housing 2 may be provided in any shape or structure as long as the portion facing the substrate 1 serves as a heat transfer path. Heat dissipation through the housing 2 may involve heat radiation, natural convection heat transfer, forced convection heat transfer, etc., in addition to heat conduction through the heat dissipation members 5 and 6.

In addition, in FIG. 1, the wiring and electronic components 3 and 4 are provided on the upper surface of the substrate 1, and the heat dissipation members 5 and 6 are arranged toward the ceiling of the housing 2, but the direction of the heat transfer path is not particularly limited. The wiring and electronic components 3 and 4 may be provided on the lower surface of the substrate 1, and the heat dissipation members 5 and 6 may be arranged toward the bottom of the housing 2.

In addition, in FIG. 1, the wiring and electronic components 3 and 4 are provided on one side of the substrate 1, but they may be provided on both sides of the substrate 1. When the wiring and electronic components 3 and 4 are provided on both sides of the substrate 1, the heat dissipation members 5 and 6 may be disposed on both sides of the substrate 1, or may be disposed on one side of the substrate 1 where a heat transfer path to both sides is secured.

FIG. 3 is a cross-sectional view of a printed circuit board showing an example of a cooling structure according to an embodiment of the present invention.
3, a cooling structure in which a plurality of heat transfer blocks 5 are stacked can also be formed for a plurality of heat generating components 3. The cooling structure according to this embodiment includes a substrate 1, a housing 2, electronic components 3 and 4, and heat dissipation members 5 and 6, similar to the cooling structure shown in FIG.

In the cooling structure shown in FIG. 3, the electronic components 3, 4 are a plurality of heat generating components 3 of different heights and a non-cooling component 4 arranged on the substrate 1. The heat dissipation members 5, 6 are a plurality of heat transfer blocks 5 made of a material with high thermal conductivity and a thin-layer heat transfer material 6 made of a material with high thermal conductivity, which are arranged between the heat generating components 3 and the housing 2.

As shown in FIG. 3, among the multiple heat transfer blocks 5 stacked on top of each other, some of the heat transfer blocks 5 can be thermally connected to each of the multiple heat generating components 3. The number of heat generating components 3 thermally connected to one heat transfer block 5 may be two or more. In addition, the type, size, and height of the heat generating components 3 thermally connected to one heat transfer block 5 are not particularly limited.

As shown in FIG. 3, the multiple heat transfer blocks 5 are preferably stacked so that the total cross-sectional area of the heat transfer blocks 5 at the same height increases from the heat generating component 3 toward the housing 2. It is also preferable that the components are arranged so that the contact areas between them have a similar relationship. That is, the heat transfer blocks 5 may have a cross-sectional area equal to that of the heat generating component 3, and a cross-sectional area larger than the total area of the heat generating components 3. In this case, it is preferable to stack the heat transfer blocks 5 so that the cross-sectional area of the heat transfer blocks 5 and the contact areas between the components increase the closer they are to the housing 2.

According to the cooling structure shown in FIG. 3, one heat transfer block 5 forms a heat transfer path for multiple heat-generating components 3, so the space on the housing 2 side where the heat transfer block 5 is not present can be reduced and the cross-sectional area of the heat transfer path by solid thermal conduction can be increased. In FIG. 3, tall components are placed between the heat-generating components 3, and the heights of the heat-generating components 3 are different from each other. However, even in such a case, since the structure is one in which multiple heat transfer blocks 5 are stacked, a heat transfer path for each heat-generating component 3 can be secured without using blocks with complex shapes.

FIG. 4 is a cross-sectional view of a printed circuit board showing an example of a cooling structure according to an embodiment of the present invention.
As shown in Fig. 4, the cooling structure in which a plurality of heat transfer blocks 5 are stacked can also be a stacked structure of three or more stages. The cooling structure according to this embodiment includes a substrate 1, a housing 2, electronic components 3 and 4, and heat dissipation members 5 and 6, similar to the cooling structure shown in Fig. 1.

In the cooling structure shown in FIG. 4, the electronic components 3 and 4 are a heat-generating component 3 and multiple tall components (non-cooled components 4) of different heights, which are arranged on the board 1. The heat dissipation members 5 and 6 are multiple heat transfer blocks 5 made of a material with high thermal conductivity and a thin-layer heat transfer material 6 made of a material with high thermal conductivity, which are arranged between the heat-generating component 3 and the housing 2.

In the cooling structure shown in FIG. 4, multiple tall components that are taller than the heat-generating component 3 are arranged around the heat-generating component 3 on the substrate 1. The tall components are different in height, and the further away from the heat-generating component 3, the taller they are. In such a structure, when a single conventional heat dissipation member is used, it is not possible to individually avoid interference with the multiple tall components, so it is necessary to make the heat dissipation member have a complex shape at the expense of processing costs or to sacrifice the cross-sectional area of the heat transfer path.

However, according to the cooling structure shown in FIG. 4, since multiple heat transfer blocks 5 are stacked, when a stacked structure of three or more layers is used, a heat transfer path with a sufficiently expanded cross-sectional area is formed without interfering with multiple tall components. As a result, unlike the conventional case where a single heat dissipation member is used, a part of the stacked heat transfer blocks 5 of a simple shape is positioned above multiple tall components. With this structure, the number and size of the heat transfer blocks 5 of a simple shape can be adjusted to accommodate the number and height of various tall components, so it is possible to avoid interference with tall components while ensuring the cross-sectional area of the heat transfer path.

As shown in FIG. 4, the heat transfer blocks 5 are preferably stacked so that the contact surface that comes into contact with the member on the housing 2 (heat dissipation section) side extends outward at a predetermined angle (θ shown in FIG. 4) or more than the contact surface that comes into contact with the member on the heat generating component 3 side. In other words, the heat transfer blocks 5 and heat transfer material 6 arranged on the upper side are preferably stacked so that the outer edge (upper edge of the side) of the upper surface of the heat transfer block 5, heat transfer material 6, and heat generating component 3 arranged on the lower side extends outward at a predetermined angle (θ) or more from the normal to the heat generating component 3.

The angle (θ) is preferably 30 degrees or more, more preferably 35 degrees or more, even more preferably 40 degrees or more, even more preferably 45 degrees or more, even more preferably 50 degrees or more, even more preferably 55 degrees or more, even more preferably 60 degrees or more. With such an angle, the heat transfer path by solid thermal conduction is expanded along the direction of thermal diffusion, allowing for efficient heat dissipation.

It is preferable that the spread of such an angle (θ) is filled in at least one direction parallel to the substrate 1, such as front-back or left-right (front, back, left, right, etc. in FIG. 4), and it is more preferable that the spread is filled in all directions parallel to the substrate 1, that is, in the directions all around the normal to the substrate 1. However, when using an aluminum alloy or the like with high thermal conductivity, a cooling effect can be obtained by uniform heating, so the structure is not limited to this.

The cooling structure according to the above embodiment is a structure in which multiple heat transfer blocks are stacked, and since blocks of simple shapes are used as the heat transfer blocks, a heat dissipation member that forms an appropriate heat transfer path can be provided at low cost. The heat transfer blocks are provided in advance in various sizes and heights, and can be rearranged as appropriate depending on the arrangement of the heat generating body and the tall body. They can also be replaced as appropriate depending on the state of the heat generating body and the board. Therefore, the heat generating body arranged on the board can be efficiently cooled at low cost while avoiding interference with the surroundings. Even if multiple heat generating bodies are arranged on the board with a tall body between them, or multiple heat generating bodies are at different heights, it is possible to efficiently cool multiple heat generating bodies.

The cooling structure according to the above embodiment can be used on a printed circuit board equipped with heat-generating components such as integrated circuits to provide an electronic device equipped with a cooling structure in which multiple heat transfer blocks are stacked. When an aluminum block made of an aluminum alloy is used as the heat transfer block, it is particularly effective for electronic devices that are exposed to an atmosphere containing sulfur components and oxidizing substances.

Specific examples of electronic devices include industrial electronic devices such as control devices, power supplies, communication devices, display devices, monitoring devices, and measuring devices, as well as personal computers, portable personal computers, mobile phones, smartphones, personal digital assistants, televisions, displays, recorders, digital cameras, video cameras, audio equipment, refrigeration and air conditioners, washing machines, and vacuum cleaners.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are included as long as they do not deviate from the technical scope. For example, the above-described embodiments are not necessarily limited to those having all of the configurations described. It is also possible to replace part of the configuration of an embodiment with another configuration, or to add another configuration to the configuration of an embodiment. It is also possible to add other configurations to, delete configurations, or replace configurations with respect to part of the configuration of an embodiment.

The present invention will be described in detail below with reference to examples, but the technical scope of the present invention is not limited to these examples.

The cooling performance of the cooling structure in which multiple heat transfer blocks are stacked (Example 1, Comparative Example 1, Comparative Example 2) was evaluated by thermal fluid analysis.

Fig. 5 is a diagram showing a cooling structure according to Example 1 of the present invention, Fig. 6 is a diagram showing a cooling structure according to Comparative Example 1, and Fig. 7 is a diagram showing a cooling structure according to Comparative Example 2.
Using the structures shown in Figs. 5, 6 and 7 as calculation systems, thermal fluid analysis was performed using the finite volume method, and the temperature of the heat-generating component 3 was evaluated as the cooling performance.

Figure 5 shows a cooling structure according to Example 1 in which multiple heat transfer blocks 5 are stacked on top of each other. Figure 6 shows a cooling structure according to Comparative Example 1 in which a single heat transfer block 5 in a rectangular parallelepiped shape is used, and multiple heat transfer blocks 5 are not stacked on top of each other. Figure 7 shows a cooling structure according to Comparative Example 2 in which a single heat transfer block 5 in the same shape as Example 1 is used, and multiple heat transfer blocks 5 are not stacked on top of each other.

In Example 1 shown in FIG. 5, two rectangular parallelepiped heating elements were set as the heating components 3. On top of each heating element (3), a rectangular parallelepiped block was individually stacked as a heat transfer block 5, and a common rectangular parallelepiped block (5) was stacked on top of that so as to be thermally connected to each of the two heating elements (3), and this was brought into contact with the structure as the housing 2. Between the heating elements (3), a rectangular parallelepiped tall structure was placed as a tall component (non-cooled component 4) that was shorter than the lower block (5) and taller than the heating elements. A sheet simulating a thermally conductive sheet was placed between each component as the heat transfer material 6.

As shown in FIG. 5, the distance between the top surface of the tall structure (4) and the bottom surface of the upper block (5) was 10 mm. The distance between the heating element (3) and the side of the tall structure (4) was 5 mm.

Inside, between the two heating elements (3), the left and right positions of the heating element (3) and the lower block (5) are aligned so that the side of the heating element (3) and the side of the lower block (5) are flush with each other. On the other hand, on the outside, the outer ends (upper edges of the outer side faces) of the upper surfaces of the lower block (5) and the upper block (5) are shaped to extend 45 degrees outward from the normal to the heating element (3) starting from the outer end (upper edge of the outer side face) of the surface of the heating element (3).

In Comparative Example 1 shown in Figure 6, similar to the structure shown in Figure 5, two rectangular parallelepiped heating elements were set as the heat generating component 3. A single rectangular parallelepiped block (5) was individually stacked on top of each heating element (3) as the heat transfer block 5, and these were brought into contact with the structure serving as the housing 2. A tall structure (4) similar to the structure shown in Figure 5 was placed between the heating elements (3). A sheet simulating a thermally conductive sheet was placed between each member as the heat transfer material 6.

In Comparative Example 2 shown in FIG. 7, two rectangular parallelepiped heating elements were set as the heating component 3, similar to the structure shown in FIG. 5. A single block (5) formed by combining the lower block (5) and upper block (5) shown in FIG. 5 was stacked on top of each heating element (3), and these were brought into contact with the structure serving as the housing 2. This block (5) was thicker than the block (5) shown in FIG. 5 by a thickness equivalent to the sheet body (6). A tall structure (4) similar to the structure shown in FIG. 5 was placed between the heating elements (3). A sheet body simulating a thermally conductive sheet was placed between each member as the heat transfer material 6.

In the structures of Example 1, Comparative Example 1, and Comparative Example 2, a heat load of 10 W was applied to the heating element corresponding to the heat generating component 3. The material of the structure (2) and the block (5) was set to A6063, an Al-Mg-Si aluminum alloy. The sheet body (6) was set to have a thickness of 1 mm and a thermal conductivity of 4.3 W/m·K. The initial temperature around the heating element was set to 25°C.

Table 1 shows the temperature of the heating element (3) after a specified heat dissipation process as a result of the thermal fluid analysis for the structures of Example 1, Comparative Example 1, and Comparative Example 2.

As shown in Table 1, the temperature of the heating element (3) in Example 1 was 3.8°C lower than that in Comparative Example 1. It can be seen that the structure in which multiple heat transfer blocks 5 are stacked is effective in avoiding interference with tall components and in expanding the cross-sectional area of the heat transfer path.

In addition, the temperature of the heating element (3) in Example 1 was 0.5°C higher than that in Comparative Example 2. This result shows that the heat loss due to the heat transfer material 6 such as a thermally conductive sheet does not significantly affect the overall cooling performance.

From these results, it can be said that a low-cost and efficient cooling structure can be realized by combining heat transfer blocks 5 of simple shapes, without having to form the heat dissipation components into complex shapes by cutting or other processes. If the thermal conductivity of the heat transfer material 6 is high, heat loss can be further reduced, so it can be said that it is preferable to use a heat transfer material 6 with a thermal conductivity of 4.3 W/m·K or more.

1: Board 2: Housing 3: Heat-generating component (electronic component)
4. Non-heat-generating components (electronic components)
5 Heat transfer block (heat dissipation member)
6 Heat transfer material (heat dissipation material)

Claims (9)

A substrate on which a heat generating element is disposed;
a heat dissipation section disposed opposite the substrate and configured to dissipate heat generated by the heat generating element to the outside;
a plurality of heat transfer blocks for conducting heat generated by the heat generating body toward the heat dissipation portion;
a heat transfer elastic body having elasticity for thermally conducting heat generated by the heat generating body toward the heat dissipation portion;
Equipped with
the heat transfer blocks are each provided as a columnar body that is a rectangular parallelepiped, a cube, a rhombic column, or a cylinder, are stacked on top of each other in a direction perpendicular to the substrate, and are disposed between the heat generating body and the heat dissipation portion;
The heat transfer elastic body is disposed between the heat transfer block and the heat dissipation portion. The cooling structure according to claim 1 ,
The cooling structure, wherein the heat transfer elastic body is disposed at one or more of between the heat transfer blocks and between the heat transfer block and the substrate. The cooling structure according to claim 1 ,
The heat transfer block is disposed so that a cross-sectional area thereof increases toward the heat dissipation portion. The cooling structure according to claim 1 ,
A cooling structure in which the heat transfer blocks are stacked so that the contact surface in contact with the heat dissipation portion extends outward by 45 degrees or more from the contact surface in contact with the heat generating element. The cooling structure according to claim 1 ,
A plurality of heat generating elements that generate heat are disposed on the substrate,
A cooling structure in which a portion of the stacked heat transfer blocks is thermally connected to each of the plurality of heat generating elements. The cooling structure according to claim 1 ,
A tall body having a height greater than that of the heating element is disposed on the substrate,
A cooling structure in which a portion of the stacked heat transfer blocks is located above the tall body. The cooling structure according to claim 1 ,
The heat transfer block is a cooling structure formed of an aluminum alloy. The cooling structure according to claim 7 ,
The heat transfer block is a cooling structure that has been anodized. A substrate on which electronic components are arranged;
a heat dissipation section disposed opposite the board and configured to dissipate heat generated by the electronic components to the outside;
a plurality of heat transfer blocks for thermally conducting heat generated by the electronic components toward the heat dissipation portion;
a heat transfer elastic body having elasticity for thermally conducting heat generated by the electronic component toward the heat dissipation portion,
The heat transfer blocks are each provided as a columnar body that is a rectangular prism, a cube, a rhomboidal prism or a cylinder, stacked on top of each other in a direction perpendicular to the substrate, and positioned between the electronic component and the heat dissipation section, and the heat transfer elastic body is positioned between the heat transfer block and the heat dissipation section. An electronic device equipped with a cooling structure.

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