Heat dissipation member, vapor chamber, and functional module

Abstract

This heat dissipation member comprises: a substrate having a hollow part and a first surface that is exposed to the hollow part; and a wick positioned in the hollow part, the wick being in contact with the first surface. The wick has a plurality of particles bonded to each other and a plurality of gap sections positioned between the plurality of particles. The region in which the wick is positioned is divided into three regions from the first surface to the end on the side opposite from the first surface. When the regions are referred to as the first region, the second region, and the third region in order from the side closer to the first surface, the average particle diameter of the particles in the first region is less than the average particle diameter of the particles in the third region.

Description

Heat dissipation member, vapor chamber and functional module

[0001] The present disclosure relates to a heat dissipation member, a vapor chamber, and a functional module.

[0002] Conventionally, there is a vapor chamber that accommodates a wick and a refrigerant in the hollow portion of a base (see JP 2021-131214 A).

[0003] A heat dissipation member according to one aspect of the present disclosure comprises: a base having a hollow portion and a first surface exposed in the hollow portion; and a wick located in the hollow portion and in contact with the first surface, wherein the wick has a plurality of particles bonded to each other and a plurality of voids located between the plurality of particles; and when the region in which the wick is located is divided into three from the first surface to the end opposite the first surface, and the three regions are referred to as a first region, a second region, and a third region from the side closest to the first surface, the average particle size of the particles in the first region is smaller than the average particle size of the particles in the third region.

[0004] Another aspect of the present disclosure provides a heat dissipation member comprising: a base having a hollow portion and a first surface exposed in the hollow portion; and a wick located in the hollow portion and in contact with the first surface, wherein the wick includes a plurality of voids; and when the region in which the wick is located is divided into three regions from the first surface to the end opposite the first surface, and the regions are referred to as a first region, a second region, and a third region from the side closest to the first surface, the average size of the voids in the first region is smaller than the average size of the voids in the third region.

[0005] The vapor chamber according to the present disclosure comprises the heat dissipation member described above and a refrigerant located in the hollow portion.

[0006] The functional module according to the present disclosure comprises: a heat-generating functional component; and the vapor chamber in which the functional component is mounted.

[0007] 5A is a perspective view showing a heat dissipation member and a vapor chamber according to a first embodiment of the present disclosure. FIG. 5B is a plan view showing a heat dissipation member and a vapor chamber according to a first embodiment of the present disclosure. FIG. 5C is a view illustrating the overall structure of a wick. FIG. 5D is a view illustrating the structure of a wick. FIG. 5E is a view illustrating the microstructure of a wick according to a second embodiment. FIG. 5F is a view illustrating particles constituting a wick according to a second embodiment. FIG. 5G is a view illustrating a cross section taken along line B-B of FIG. 5A. FIG. 5H is a view illustrating a cross section of a wick according to a second embodiment. FIG. 5I is an enlarged view illustrating a cross section of a wick according to a second embodiment. FIG. 5J is a cross section showing the range from the first surface to the second surface of a hollow portion according to a second embodiment. FIG. 5I is a view illustrating the orientation of particles in a wick according to a second embodiment. FIG. 5I is a view illustrating particles constituting a wick according to a third embodiment. FIG. 5I is a view illustrating a functional module according to a fourth embodiment of the present disclosure. FIG. 5J is a view illustrating a functional module according to a fifth embodiment of the present disclosure. FIG. 5J is a view illustrating a functional module according to a sixth embodiment of the present disclosure. FIG. 5J is a view illustrating a functional module according to a seventh embodiment of the present disclosure. FIG. 5J is a view illustrating a functional module according to an eighth embodiment of the present disclosure.

[0008] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. Below, the up and down directions may be indicated when describing each part. However, these directions may be different from the directions when the heat dissipation member 10 and the vapor chamber 1 are in use.

[0009] (Embodiment 1) Fig. 1A is a perspective view showing a heat dissipation member and a vapor chamber according to embodiment 1 of the present disclosure. Fig. 1B is a plan view showing a heat dissipation member and a vapor chamber according to embodiment 1 of the present disclosure. Fig. 2 is a diagram illustrating the overall structure of the wick 13. Fig. 2 is a cross-sectional view taken along line A-A in Fig. 1B.

[0010] The heat dissipation member 10 according to the first embodiment of the present disclosure includes a base 11 having a hollow portion 111 and a wick 13 located in the hollow portion 111. In Figures 1B and 2, the wick 13 is shown shaded. The wick 13 is omitted in Figure 1A. The vapor chamber 1 according to the first embodiment of the present disclosure includes the heat dissipation member 10 and a refrigerant located in the hollow portion 111. The hollow portion 111 may be sealed and decompressed. The refrigerant is a fluid that undergoes a phase transition between a gas phase and a liquid phase, and examples of the refrigerant that may be used include water, acetone, methanol, ammonia, and the like.

[0011] The base 11 may have a first surface 112 exposed to the hollow portion 111 and a second surface 113 exposed to the hollow portion 111 and facing the first surface 112. The first surface 112 may be an inner top surface, and a heat source may be mounted on the upper portion of the base 11. The second surface 113 may be an inner bottom surface, and a lower portion of the base 11 may be cooled. The base 11 may be flat, and in this case, the heat dissipation member 10 may be called a heat sink.

[0012] The material of the base 11 may be a material with high thermal conductivity, such as a metal such as copper or aluminum, or a ceramic such as aluminum nitride ceramic. The base 11 may be made of a single material, or may be made of a combination of multiple materials, such as a bottom plate made of ceramic and a side wall and top plate made of metal.

[0013] The base 11 may include a plurality of support columns 115 that support the hollow portion 111. The support columns 115 may be positioned across the hollow portion 111 from the first surface 112 to the second surface 113.

[0014] The wick 13 may have a plurality of minute voids G (see FIG. 3 ) and may be configured to transport the liquid phase refrigerant by capillary force generated in the minute voids G. The wick 13 may be positioned so as to be in contact with the first surface 112. The wick 13 may be positioned so as to be spaced apart from the second surface 113.

[0015] Furthermore, the hollow portion 111 may include, in a planar perspective view, a region 111A where the wick 13 is located and a region 111B where the wick 13 is not located. In Fig. 1B, the regions 111A and 111B are indicated by dashed dotted lines. "Where the wick 13 is not located in a planar perspective view" means that the wick 13 is not located between the first surface 112 and the second surface 113. The region 111B may function as a passage through which the gas-phase refrigerant flows.

[0016] In the vapor chamber 1 configured as described above, for example, a heat source is located on a portion of the upper surface of the base 11, and a cooling unit is located on the bottom surface of the base 11. The liquid-phase refrigerant transported to the vicinity of the first surface 112 by the capillary force of the wick 13 undergoes a phase transition to a gas-phase refrigerant by receiving heat transfer from the heat source via the first surface 112. This phase transition absorbs a large amount of heat from the heat source. The gas-phase refrigerant then flows through the void G in the wick 13 and the region 111B where the wick 13 is not located, releasing heat via the second surface 113, thereby transitioning to a liquid-phase refrigerant. This phase transition releases a large amount of heat to the cooling unit. This cycle is repeated, allowing the vapor chamber 1 to transport a large amount of heat from the heat source to the cooling unit.

[0017] <Wick Structure> Fig. 3 is a diagram illustrating the structure of the wick 13. The wick 13 may be configured by bonding a plurality of particles 40 together. The wick 13 may have a structure in which the entire plurality of particles 40 is fixed by bonding portions of adjacent particles 40 together. Bonding between adjacent particles 40 may be achieved by a sintering process to an extent that the densification of the plurality of particles 40 does not proceed.

[0018] The component of each particle 40 may be a metal such as copper. The particles 40 may be spherical as shown in Figure 3. Particles 40 with this structure can be manufactured by atomization or electric field method.

[0019] The wick 13 may be fixed in the hollow portion 111 so as to contact the first surface 112 (see FIG. 2 ). The wick 13 may be fixed in the hollow portion 111 so as to contact the inner surface of the base 11 and the side surface of the support 115. This fixing may be achieved by bonding the first surface 112 and the side surface to some of the particles 40 that contact these surfaces. This bonding may be achieved by a sintering process to an extent that the densification of the multiple particles 40 does not progress.

[0020] The bonding between the particles 40 in the wick 13 and the bonding between the particles 40 and the first surface 112 may be achieved by the same sintering process. That is, by placing a plurality of particles 40 in the hollow portion 111 with the first surface 112 facing downward and performing a sintering process to an extent that does not cause the plurality of particles 40 to become densified, the bonding between the plurality of particles 40 and the bonding between the wick 13 and the first surface 112 can be achieved.

[0021] <Size of Voids G> Voids G may be located between multiple particles 40. The voids G may be spaces through which a gas or liquid refrigerant can move. In a cross-sectional photograph, the voids G are easily identifiable because their contrast is significantly different from that of the particles 40. Therefore, the size and cross-sectional shape of the voids G can be observed from the cross-sectional photograph. Almost all of the voids G are connected in three-dimensional space. However, by dividing the voids G into blocks in the cross-sectional photograph, the connected voids G can be considered as a collection of multiple voids G. Each void G in the cross section is defined as follows. That is, first, in a linearly continuous void region, the maximum width in a direction perpendicular to the linear direction is determined. Next, the portion that is connected to the void region and has a width of 1 / 5 or less of the maximum width is defined as the periphery of one void G. With this definition, an area that includes the void region having the above-mentioned maximum width and is surrounded by the particle 40 and the above-mentioned periphery can be identified as one void G. The size of each void G can then be determined. The size of one void G is defined as the square root of the area of ​​that void G. The average size of the many voids G contained in a certain area can be calculated based on the total area of ​​the voids G in that area and the number of voids G counted in that area.

[0022] <Particle Diameter of Particles 40> Because the particles 40 are cut at various locations in a cross-sectional photograph, it is difficult to determine the particle diameter of each particle 40. However, the particle diameter of each particle 40 can be easily determined by observing the surface of the wick 13 with a scanning electron microscope (SEM). The particle diameter is the average of the major and minor axes. The average particle diameter of multiple particles 40 in a certain region is defined as the average of particle diameters excluding the smallest 3% and largest 3% of the particle size distribution in that region as outliers. When measuring the particle diameter of particles 40 in a certain region located inside the wick 13, the region is broken or cut to expose the region. If there are particles 40 that do not maintain their original shape due to breaking or cutting, the particles 40 can be peeled off and the region observed with an SEM to determine the particle diameter of the region.

[0023] <Particle Size Distribution of Particles 40 and Size Distribution of Voids G> Next, the particle size distribution of the particles 40 in the wick 13 and the size distribution of the voids G will be described. In this description, the region in which the wick 13 is located is divided into three regions from the first surface 112 to the end opposite the first surface 112, and these regions are referred to as a first region R1, a second region R2, and a third region R3 from the side closest to the first surface 112 (see FIGS. 2 and 3). The height width of the first region R1 and the third region R3 is set to a length that can accommodate two to three particles 40 on average.

[0024] In the wick 13, the average particle size φ1 of the particles 40 in the first region R1 may be smaller than the average particle size φ3 of the particles in the third region, as shown in the following formula (1): φ1 < φ3 (1) The ratio of the average particle sizes φ1 and φ3 may be 1.2 times or more, 2.0 times or more, or 5.0 times or more.

[0025] In the wick 13, the average size w1 of the voids G in the first region R1 may be smaller than the average size w3 of the voids G in the third region, as shown in the following formula (2): w1 < w3 (2) The size ratio of the average sizes w1 and w3 of the voids G may be 1.2 times or more, 2.0 times or more, or 5.0 times or more.

[0026] The above particle size distribution and size distribution of the voids G can be achieved by the following manufacturing method. That is, the pre-sintered powder that will become the wick 13 is spread in the hollow portion 111 so that the smaller particles 40 are more prevalent in the first region R1 and the larger particles 40 are more prevalent in the third region R3. Depending on how the powder is spread in this way, the average size of the voids G in the first region R1 and the third region R3 also differ. Then, in this state, a sintering process is performed so that the multiple particles 40 are bonded together.

[0027] The above average particle diameters φ1 and φ3, as well as the average sizes w1 and w3, enhance the capillary force of the wick 13 in the first region R1 close to the heat source, while also enhancing the ease of refrigerant movement in the third region R3 away from the heat source. This reduces localized drying of the wick 13 in the first region R1 close to the heat source, and facilitates the smooth delivery of gaseous refrigerant from the third region R3 and the smooth intake of liquid refrigerant. This contributes to the excellent heat dissipation characteristics of the vapor chamber 1.

[0028] (Embodiment 2) FIG. 4 is a diagram illustrating a wick 13 employing particles 50 according to embodiment 2. FIGS. 5A and 5B are diagrams illustrating the particles 50. Embodiment 2 may be similar to embodiment 1, except for the particles 50 constituting the wick 13. The average particle diameters φ1 and φ3 in the first region R1 and the third region R3 may differ, as may the average sizes w1 and w3 of the voids G in the first region R1 and the third region R3. This configuration enhances the capillary force of the wick 13 in the first region R1, which is closer to the heat source, while improving the ease of refrigerant movement in the third region R3, which is farther from the heat source. This reduces localized drying of the wick 13 in the first region R1, which is closer to the heat source, and facilitates the delivery of gaseous refrigerant from the third region R3 and the intake of liquid refrigerant. This contributes to the excellent heat dissipation characteristics of the vapor chamber 1.

[0029] In the second embodiment, the wick 13 may also have a structure in which a plurality of particles 50 are fixed together as a whole by bonding portions of adjacent particles 50 together. The component of each particle 50 may be a metal such as copper. Bonding between adjacent particles 50 may be achieved by a sintering process to an extent that does not promote densification of the plurality of particles 50. The particle diameter of the particles 50 may be 1 μm to 1000 μm, 10 μm to 700 μm, or 20 μm to 500 μm. The particle diameter D50 of the particles 50 may be 20 μm, 100 μm, or 200 μm. The particle diameter refers to the average of the major axis and the minor axis. The particle diameter D50 refers to the median particle diameter of the particle size distribution.

[0030] As shown in Fig. 5A, each of the plurality of particles 50 may have a structure in which a plurality of protrusions 51 protrude obliquely radially from an imaginary central axis 53 and are arranged in multiple stages along the imaginary central axis 53. This structure can be formed by growing the particles 50 according to the crystal orientation in electrolytic plating. The plurality of protrusions 51 may include a protrusion 51 having a maximum thickness point T midway from the base to the tip of the protrusion 51.

[0031] The above-described structure of the particles 50 makes it easy to realize a wick 13 that includes many large voids G (see FIG. 4 ) between the particles 50. That is, when a powder of the particles 50 is laid in the hollow portion 111 during the manufacturing process of the wick 13, the above-described structure causes many catches between adjacent particles 50. These catches then create many large voids G between the particles 50. Then, by sintering the particles 50, the particles 50 are bonded together, making it easy to realize a wick 13 that includes many large voids G.

[0032] Furthermore, there are small gaps g between the multiple small protrusions 51 on the surface of each particle 50. Therefore, the wick 13 contains large gaps G, small gaps G, and even smaller gaps g dispersed throughout. The large gaps G facilitate the movement of the refrigerant, while the small gaps g create a strong capillary force. This structure therefore facilitates the retention and transport of liquid refrigerant and the discharge of gaseous refrigerant, achieving excellent heat dissipation characteristics for the vapor chamber 1. This also achieves heat dissipation characteristics that are particularly suited to situations where a large amount of heat needs to be released with low thermal resistance.

[0033] Furthermore, the plurality of particles 50 may include particles 50 having a structure in which the imaginary central axes 53, 53 are branched into multiple parts along the way. The branches are in an oblique direction, and the oblique direction may be one direction included in the oblique radial direction in which the protrusions 51 protrude.

[0034] Furthermore, by including particles 50 with this structure, when a powder of multiple particles 50 is laid in the hollow portion 111 during the manufacturing stage of the wick 13, more catches can be generated between adjacent multiple particles 50. This catch can then generate larger voids G between the multiple particles 50. Then, by the subsequent sintering process, the multiple particles 50 are bonded together, thereby realizing a wick 13 that includes larger voids G, and achieving good heat dissipation characteristics for the vapor chamber 1.

[0035] Furthermore, each of the plurality of particles 50 may have a cone-shaped portion 55 in which the diameter of the particle 50 gradually increases from one end of the imaginary central axis 53 to the middle. The cone shape may also be called a circular cone shape.

[0036] Furthermore, the cone-shaped portion 55 allows for more catches to be generated between adjacent particles 50 when powder, which is a plurality of particles 50, is laid in the hollow portion 111 during the manufacturing stage of the wick 13. This catch allows for more large voids G to be generated between the particles 50. Then, by the subsequent sintering process, the particles 50 are bonded together, thereby realizing a wick 13 that includes more large voids G, and achieving good heat dissipation characteristics for the vapor chamber 1.

[0037] FIG. 5B shows a cross-sectional view of the particle 50 of FIG. 5A taken along line B-B. When three adjacent protrusions 51 among the multiple protrusions 51 included in one particle 50 are referred to as a first protrusion 51A, a second protrusion 51B, and a third protrusion 51C, the first protrusion 51A may have a maximum thickness point T (see FIG. 5A ) midway from the base to the tip. In this case, as shown in FIG. 5B , the gap g1 between the first protrusion 51A and the second protrusion 51B and the gap g2 between the first protrusion 51A and the third protrusion 51C may be connected closer to the base than the maximum thickness point T. Note that although two maximum thickness points T are shown in FIG. 5A , many protrusions 51 having maximum thickness points are included.

[0038] The structure of the gaps g1 and g2 creates fine, long gaps g1 and g2, which generate a strong capillary force. Therefore, each particle 50 provides a high retention force for the liquid refrigerant, reducing the occurrence of localized drying of the wick 13. This allows the refrigerant to smoothly transition between the liquid and gas phases throughout the wick 13, contributing to the excellent heat dissipation characteristics of the vapor chamber 1.

[0039] <Details of Void G> Fig. 6 is a diagram showing a cross section of the wick 13. Hatching of the cross section of the particle 50 is omitted in Fig. 6. The multiple voids G included in the wick 13 may include a first void G1 in the cross section having a width wG larger than the particle diameter w50 of the adjacent particle 50. The above cross section may be a cross section in any direction.

[0040] According to this configuration, the first void G1 having a width wG larger than the particle diameter w50 of the particles 50 is included, which improves the ease of movement of the liquid or gas phase refrigerant through the first void G1, thereby contributing to good heat dissipation characteristics of the vapor chamber 1.

[0041] In the cross section of the wick 13, there may be five or more connection points cn between the first gap G1 and another gap G. When the boundaries of each gap G and the first gap G1 are defined as above, the first gap G1 in FIG. 6 is connected to another adjacent gap G via six connection points cn.

[0042] According to this configuration, the large first gap G1 is connected to another gap G at five or more connection points cn in the cross section, which further improves the ease of movement of the liquid or gas phase refrigerant through the first gap G1, thereby contributing to the good heat dissipation characteristics of the vapor chamber 1.

[0043] <Details of the Gaps g Between the Particles 50> Figure 7 is an enlarged view showing the cross section of the wick 13. Hatching of the cross section of the particles 50 is omitted in Figure 7. In the cross section of the wick 13, the width wg of the gaps g between the particles 50 may be smaller than the width wG of the voids G connected to the gaps g. With this configuration, the wick 13 includes voids G of various sizes and gaps g with widths wg even smaller than the width of the voids G. Thus, the voids G improve the ease of refrigerant movement, while the gaps g improve the refrigerant retention force. This reduces the occurrence of localized drying of the wick 13 and facilitates phase transition of the refrigerant and exchange between the liquid and gas phases. This contributes to the excellent heat dissipation characteristics of the vapor chamber 1.

[0044] The multiple particles 50 include adjacent first particles 50A and second particles 50B (see FIG. 8 ), and the gaps gA between the first particles 50A and the gaps gB between the second particles 50B may be in contact. That is, the protrusions 51 a, 51 a of the first particles 50A, which sandwich the gap gA, and the protrusions 51 b, 51 b of the second particles 50B, which sandwich the gap gB, are bonded by a sintering process, resulting in a structure in which the gaps gA and gB are in contact with each other. This configuration allows the fine gaps gA and gB to continue for a long period of time, allowing more refrigerant to be held in the gaps g. This further reduces localized drying of the wick 13, contributing to the excellent heat dissipation characteristics of the vapor chamber 1.

[0045] Furthermore, the direction in which the gap gA between the first particles 50A expands may intersect with the direction in which the gap gB between the second particles 50B expands. That is, the gaps gA and gB may be in contact with each other so that an imaginary plane extending along the gap gA between the first particles 50A intersects with an imaginary plane extending along the gap gB between the second particles 50B. With this configuration, the narrow gap G between the first particles 50A and the second particles 50B communicates with the gaps gA and gB, and a strong capillary force can be generated in this portion.

[0046] <Overall Structure of Wick> Fig. 8 is a cross-sectional view showing the range from the first surface 112 to the second surface 113 of the hollow portion 111. In Fig. 8, the cross section of the particle 50 is shown in white, and the void portion G is shown in hatching.

[0047] The cross section of the wick 13 may have a communication passage H that communicates from the first surface 112 to the end on the opposite side of the first surface 112 via a gap G. This configuration allows the gas phase refrigerant to be smoothly transported from the first surface 112 side of the wick 13 to the opposite side via the communication passage H. Furthermore, the capillary force of the small gaps G located around the communication passage H or the gaps g between the particles 50 allows the liquid phase refrigerant to be smoothly transported from the opposite side of the first surface 112 of the wick 13 to the first surface 112 side. Therefore, heat is smoothly transported due to the phase transition of the refrigerant, contributing to the good heat dissipation characteristics of the vapor chamber 1.

[0048] In the cross section of the wick 13, the plurality of voids G may include second voids G2 that are in contact with the first surface 112 and have a width wG2 in the normal direction to the first surface 112 that is greater than the average particle size φ1 of the particles 50 in the first region R1. This configuration increases the amount of liquid-phase refrigerant that is returned to the first surface 112. This increases the amount of phase transition of the refrigerant at the first surface, thereby increasing the amount of heat absorbed via the first surface 112.

[0049] The gaps g between the particles 50 may be adjacent to the region 111B where the wick 13 is not located. In other words, if the region 111B is considered a flow path for the gaseous refrigerant, the gaps g between the particles 50 may be adjacent to the flow path. When the liquid-phase transfer path is adjacent to the flow path for the gaseous refrigerant, localized drying of the liquid-phase transfer path is likely to occur at that location. On the other hand, providing more walls than necessary to separate the two narrows the internal space. However, in embodiment 2, the flow path for the gaseous refrigerant is adjacent to minute gaps g that generate strong capillary forces, thereby reducing the occurrence of the localized drying. Therefore, the flow of the gaseous refrigerant and the reflux of the liquid-phase refrigerant counter to the flow are smooth, contributing to the excellent heat dissipation characteristics of the vapor chamber 1.

[0050] As shown in FIGS. 2 and 8 , the hollow portion 111 may have a space 111c between the wick 13 and the second surface 113. Furthermore, the space 111c may have irregularities 111c1 and 111c2 in the direction in which the first surface 112 and the second surface 113 face each other. One of the irregularities 111c1 may be due to the irregular shape of the end surface of the wick 13, and the other irregularity 111c2 may be due to the irregular shape of the second surface 113. The space 111c may have only one of the irregularities 111c1 and 111c2. With this configuration, the irregularities 111c1 and 111c2 create narrow and wide portions in the space 111c. Gas-phase refrigerant flows more easily through the wide portions, and liquid-phase refrigerant flows more easily through the narrow portions. Therefore, in the space 111c, there are areas where the gas phase refrigerant can easily flow and areas where the liquid phase refrigerant can easily flow, and the refrigerant can be smoothly circulated. This contributes to the excellent heat dissipation characteristics of the vapor chamber 1.

[0051] <Particle Orientation> Fig. 9 is a diagram illustrating the orientation of the particles 50 in the wick 13. When viewed from any direction, the vertices 55a of the particles 50 may be oriented in multiple dispersed directions. In Fig. 9, the orientation of the vertices 55a is indicated by dashed arrows.

[0052] The apex 55a refers to the apex of the cone-shaped portion 55, and the direction in which the apex 55a faces refers to the direction along the center line of the cone-shaped portion 55, toward the apex 55a. "Facing in multiple dispersed directions when viewed from one direction" is defined as follows: When an arbitrary rectangular region containing 10 vertical and 10 horizontal particles is selected and four angular ranges are set within the rectangular region, dividing at least 360 degrees into four, the particles 50 located on the surface of the rectangular region include four particles 50 facing in each of the four angular ranges. The "arbitrary rectangular region" can be selected not only on the outer surface of the wick 13 but also inside the wick 13. To select an arbitrary rectangular region within the wick 13, the wick 13 is cut or broken at a target location, and if there are particles 50 in the target location that do not maintain their original shape, the particles 50 are peeled off. By performing this processing, a rectangular region can be set at a target location within the wick 13, and the rectangular region can be observed using an SEM.

[0053] According to the above configuration, the vertices 55a of the particles 50 are oriented in a plurality of dispersed directions, resulting in a plurality of voids G of appropriately dispersed sizes being positioned between the particles 50. This allows for smooth circulation of the refrigerant through the wick 13, contributing to the excellent heat dissipation characteristics of the vapor chamber 1.

[0054] 9, the plurality of particles 50 may include a third particle 50C in which the apex 55a of the particle 50 faces the adjacent gap G. The particle 50 has many gaps g formed between the plurality of protrusions 51 on the side opposite to the apex 55a of the cone-shaped portion 55. Therefore, in a single particle 50, the liquid-phase refrigerant tends to easily move from the apex 55a to the opposite side.

[0055] According to the above configuration, the apex 55a faces the gap G, which facilitates the transfer of liquid-phase refrigerant away from the gap G. When a large amount of gas-phase refrigerant flows into the gap G near the heat source, localized drying is likely to occur near the gap G. However, in particles 50 oriented as described above, the cone-shaped portions 55 function as partition walls, improving the ability to retain liquid-phase refrigerant in the gaps g between particles 50 adjacent to the gap G. Therefore, the flow of gas-phase refrigerant through the gap G and the return flow of liquid-phase refrigerant counter to this flow are smooth, contributing to the excellent heat dissipation characteristics of the vapor chamber 1.

[0056] The plurality of particles 50 may include a fourth particle 50D in which the side opposite to the vertex 55a of the particle 50 faces the adjacent gap G, as shown in FIG.

[0057] With this configuration, when a large amount of gas-phase refrigerant flows into the gap G near the heat source, the wide portion opposite the apex 55a faces the gap G, thereby reducing the amount of gas-phase refrigerant entering the gap G. This reduces interference between the gap G through which the gas-phase refrigerant flows and the area through which the liquid-phase refrigerant returns. This allows for smooth flow of the gas-phase refrigerant and the return of the liquid-phase refrigerant that flows against the flow, contributing to the excellent heat dissipation characteristics of the vapor chamber 1.

[0058] <Embodiment 3> Figure 10 is a diagram showing particles 60 constituting the wick 13 of embodiment 3. Embodiment 3 may be similar to embodiment 1, except for the particles 60 constituting the wick 13. The average particle diameters φ1 and φ3 in the first region R1 and the third region R3 may differ, as may the average sizes w1 and w3 of the voids G in the first region R1 and the third region R3. This configuration enhances the capillary force of the wick 13 in the first region R1 close to the heat source, while improving the ease of refrigerant movement in the third region R3 away from the heat source. This reduces localized drying of the wick 13 in the first region R1 close to the heat source, and facilitates the smooth delivery of gas-phase refrigerant and the smooth uptake of liquid-phase refrigerant from the third region R3. This contributes to the excellent heat dissipation characteristics of the vapor chamber 1.

[0059] The configurations of the arrangement of the plurality of particles 50 and the voids G, the overall structure of the wick 13, and the gaps g between the protrusions 51 of each particle 50 described in embodiment 2 may also be applied to the wick 13 and particles 60 of embodiment 3. However, the particles 60 of embodiment 3 do not have a structure in which the protrusions 51 have directional properties, as in embodiment 2. Furthermore, the particles 60 of embodiment 3 do not have the cone-shaped portions 55 of embodiment 2. Therefore, the configurations of the directionality of the protrusions 51 and the configurations of the cone-shaped portions 55 shown in embodiment 2 do not apply to the wick 13 of embodiment 3.

[0060] In the third embodiment, the wick 13 may also have a structure in which the plurality of particles 60 are fixed as a whole by bonding portions of the particles 60 together. The component of each particle 60 may be a metal such as copper. Bonding between adjacent particles 60 may be achieved by a sintering process to an extent that the plurality of particles 60 do not become densified. The particle diameter of the particles 60 may be 1 μm to 1000 μm, 5 μm to 700 μm, or 10 μm to 500 μm. The particle diameter D50 of the particles 60 may be 5 μm, 50 μm, or 100 μm. The particle diameter refers to the average of the major axis and the minor axis. The particle diameter D50 refers to the median particle diameter of the particle size distribution.

[0061] Each of the plurality of particles 60 may have a structure in which a plurality of protrusions 61, each having a maximum thickness partway from the base to the tip, protrude in at least four mutually different directions, as shown in Fig. 9. The four directions may include components of three-dimensional directions. In other words, when the four directions are referred to as first to fourth directions, the four directions may be directions in which the third or fourth direction intersects with a plane along the first and second directions.

[0062] The above structure of the particle 60 can be produced, for example, by first forming a plurality of fine powder particles by atomization, and then sintering the gathered fine powder particles to a degree that does not cause the fine powder particles to become denser. Fine powder particles that are nearly spherical are formed by atomization, and the surrounding fine powder particles are sintered together, forming protrusions 61 that have a maximum thickness point T midway from the base to the tip.

[0063] The bonding between the fine powder particles by the sintering process is stronger than the bonding between the particles 60 in the wick 13. Therefore, by measuring the width of the bonding area through SEM observation, it is possible to distinguish between the former type of bonding and the latter type of bonding. By using the latter type of bonding as the boundary between one particle 60 and another particle 60, it is possible to identify the individual particles 60 and measure the particle size of each particle 60.

[0064] Although the particle 60 in FIG. 9 has a plurality of protrusions 61 spaced apart, some or all of the protrusions 61 may be close to each other, with minute gaps between the protrusions 61 .

[0065] According to the wick 13 of the third embodiment, the plurality of protrusions 61 of the particles 60 can easily realize a wick 13 that includes many large voids G between the plurality of particles 60. That is, in the manufacturing stage of the wick 13, when a powder of the plurality of particles 60 is laid in the hollow portion 111, many of the protrusions 61 cause a large number of catches between adjacent particles 60. These catches then create many large voids G between the plurality of particles 60. Then, by bonding the plurality of particles 60 through a sintering process, a wick 13 that includes many large voids G can easily be realized.

[0066] Furthermore, the surface of each particle 60 may contain small gaps g between the multiple protrusions 61. Therefore, the wick 13 contains large gaps G, small gaps G, and even smaller gaps g dispersed therein. This structure allows for smooth retention and transport of liquid-phase refrigerant and discharge of gas-phase refrigerant, achieving good heat dissipation characteristics for the vapor chamber 1. In particular, heat dissipation characteristics suitable for dissipating a large amount of heat with low thermal resistance are achieved.

[0067] (Functional Module) FIGS. 11A to 12C are diagrams illustrating functional modules according to embodiments 4 to 8 of the present disclosure, respectively. Functional modules 400A to 400E according to embodiments 4 to 8 each include a heat-generating functional component 410A to 410E and a vapor chamber 1 of an embodiment in which the functional component 410A to 410E is mounted. Specific examples of functional modules 400A to 400E are described below, but the following structure is merely an example, and various modifications are possible to the detailed structure, etc. Detailed illustrations of the internal structure of the vapor chamber 1 are omitted in FIGS. 11A to 12C. The vapor chamber 1 may be replaced with any of the vapor chambers 1 of the other embodiments described above.

[0068] (Functional Module of Fourth Embodiment) The functional module 400A of the fourth embodiment may be a light source module, and the functional component 410A may be a light emitting element such as an LED (Light Emitting Diode) or an LD (Laser Diode). The LD may be configured to output laser light for processing or laser light for illumination.

[0069] The functional component 410A may be mounted on the vapor chamber 1 via a submount 420. The submount 420 is a substrate smaller than the vapor chamber 1 and may be made of ceramics such as silicon nitride, silicon carbide, aluminum nitride, or aluminum oxide. Multiple functional components 410A may be mounted on the mounting portion 401. The mounting portion 401 corresponds to the mounting portion for the heat source in the vapor chamber 1.

[0070] The vapor chamber 1 has a sidewall 430 that surrounds the periphery of the mounting portion 401 of the base 11, and the mounting portion 401 may be located on the inner bottom surface of a recess 431 surrounded by the sidewall 430. The opening of the recess 431 may be covered by a light-transmitting member 432 such as a lens. The light-transmitting member 432 may be bonded to the sidewall 430 to seal the recess 431. The sidewall 430 has a horizontal through-hole 433, and a conductive member 434 that transmits operating power to the functional component 410A may be bonded to the through-hole 433. A cooling mechanism (not shown) may be located below the base 11.

[0071] According to the functional module 400A of the fourth embodiment, a large amount of heat can be dissipated from the functional component 410A, which is a light-emitting element, through the vapor chamber 1. Therefore, the functional component 410A, which is a light-emitting element, can stably emit light with high brightness. Furthermore, when the functional module 400A has a plurality of functional components 410A, which are light-emitting elements, the high heat dissipation capability of the vapor chamber 1 can achieve uniform heat distribution among the plurality of functional components 410A, thereby achieving uniform brightness among the plurality of functional components 410A.

[0072] (Functional Module of Embodiment 5) The functional module 400B of Embodiment 5 may be a wireless module that transmits wireless signals via a wireless base station or the like. The functional component 410B may be a signal processing circuit such as a beam forming integrated circuit (BFIC) that transmits wireless signals with directionality via an array antenna. Multiple functional components 410B may be mounted on the mounting section 401. The functional component 410B, which is a signal processing circuit, may be connected to an antenna substrate 441, such as a phased array antenna module (PAAM) substrate, on which an array antenna is mounted. That is, multiple functional components 410B may be mounted on the mounting section 401, an antenna substrate 441 may be located above the multiple functional components 410B, and multiple antennas 441a (e.g., patch antennas) may be located above the antenna substrate 441.

[0073] The vapor chamber 1 may be located between an antenna substrate 441 and another substrate 443 located below the antenna substrate 441 via a spacer 442. Furthermore, a shield case 444 may be located below the substrate 443. The substrate 443 may have an opening 443a, and a heat dissipation component 445 such as a heat pipe embedded in the shield case 444 may extend inside and outside the shield case 444. The heat dissipation component 445 may contact the vapor chamber 1 from below via the opening 443a, and may conduct heat from the vapor chamber 1 to the outside of the shield case 444.

[0074] According to the functional module 400B of the fifth embodiment, a large amount of heat can be dissipated from the functional component 410B, which is a signal processing circuit, via the vapor chamber 1. This allows for stable transmission of wireless signals. This contributes to increasing the power of the wireless signals, i.e., increasing the output of wireless radio waves, and reducing the module volume.

[0075] (Functional Module of Embodiment 6) The functional module 400C of Embodiment 6 may be a computer module in which a computing LSI (Large Scale Integration) is used as a functional component 410C. The functional component 410C may be an LSI for AI (Artificial Intelligence) processing, an LSI for cloud processing, an LSI for display calculation, an LSI for calculation mounted on a workstation, or any of a variety of other LSIs. In addition to the above LSI, the functional component 410C may also include a memory IC (Integrated Circuit) used by the LSI.

[0076] One or more functional components 410C may be mounted on a module substrate 451 such as a PCB (Printed Circuit Board), while the vapor chamber 1 may be incorporated so that it contacts the functional components 410C from the side opposite the module substrate 451. Here, contact is not limited to direct contact but also includes connection via a material with high thermal conductivity (e.g., a heat transfer sheet, heat transfer grease, etc.) 452. A heat dissipation component 453, such as a heat pipe 453a and a cooling fin 453b connected to the heat pipe 453a, may be connected below the base 11 of the vapor chamber 1. Furthermore, the functional module 400C may have a cooling device 454, such as a fan, that cools the heat dissipation component 453.

[0077] According to the functional module 400C of embodiment 6, a large amount of heat can be dissipated from the functional components 410C, such as the LSI and memory IC, via the vapor chamber 1. This allows stable computational processing by the functional components 410C. This allows the functional module 400C to accommodate the high computing power of the LSI, achieving a functional module 400C with high computing power. Furthermore, the vapor chamber 1 can dissipate heat from the functional components 410C, such as the LSI and memory IC, in response to increased heat generation due to miniaturization of wiring within the LSI, high-speed operation, and the like, as well as increased heat generation due to the three-dimensional mounting of the LSI and memory IC.

[0078] (Functional Module of Embodiment 7) The functional module 400D of Embodiment 7 may be a sensor module in which an image sensor is used as a functional component 410D. The vapor chamber 1 may have a convex portion 461 formed by a portion of the base 11 protruding, and the mounting portion 401 may be located on top of the convex portion 461.

[0079] The functional module 400D, which is a sensor module, may have a package 462 that seals the functional component 410D and a light-transmitting member 463 such as a lens. The package 462 may have an opening 464 in a portion thereof, and the vapor chamber 1 and the package 462 may be joined so that the convex portion 461 fits into the opening 464. The package 462 may have built-in wiring for transmitting electrical signals and power, and electrical signals and power may be transmitted between the functional component 410D and the outside of the package 462 via the wiring. A cooling mechanism (not shown) may be located below the vapor chamber 1.

[0080] According to the functional module 400D of the seventh embodiment, a large amount of heat can be dissipated from the functional component 410D, which is an image sensor, via the vapor chamber 1. Therefore, a high-performance image sensor that generates a large amount of heat and performs high-speed information processing can be applied as the functional component 410D, which can contribute to improving the functionality of the functional module 400D.

[0081] (Functional Module of Embodiment 8) The functional module 400E of Embodiment 8 may be a power module in which a power semiconductor for power control is used as the functional component 410E. The power semiconductor may be a switching element or a diode. The functional module 400E includes multiple vapor chambers 1 and multiple functional components 410E, and the multiple vapor chambers 1 may be mounted on a single insulating plate 471. The insulating plate 471 may be made of ceramics such as silicon nitride, silicon carbide, aluminum nitride, or aluminum oxide. A heat dissipation fin 475 may be attached to the underside of the insulating plate 471 via a metal heat dissipation plate 474. The vapor chambers 1 and the heat dissipation plate 474 may be bonded to the insulating plate 471 via a bonding material 472. The upper wall of the vapor chamber 1 may be a conductive member, and a wiring member 476 may be electrically connected to the upper wall, and the functional component 410E may be electrically connected so that current flows through the wiring member 476 and the upper wall. The periphery of the vapor chamber 1 , the functional component 410E, the insulating plate 471 and the heat sink 474 may be sealed with a molding material 473 .

[0082] According to the functional module 400E of the eighth embodiment, a large amount of heat can be dissipated from the functional component 410E, which is a power semiconductor, through the vapor chamber 1. Therefore, a high-output power semiconductor that generates a large amount of heat can be used as the functional component 410E, and further, the functional module 400E can be highly integrated and miniaturized.

[0083] The embodiments of the present disclosure have been described above. However, the present invention is not limited to the above embodiments. For example, in the above embodiments, the base 11 is shown to be flat, but the base 11 may have a shape including a pipe. Other details shown in the embodiments can be modified as appropriate without departing from the spirit of the invention.

[0084] An embodiment of the present disclosure is described below. In one embodiment, (1) a heat dissipation member includes: a base having a hollow portion and a first surface exposed in the hollow portion; and a wick located in the hollow portion and in contact with the first surface, wherein the wick has a plurality of particles bonded to one another and a plurality of voids located between the plurality of particles, and when a region in which the wick is located is divided into three from the first surface to an end of the wick opposite to the first surface, and the three regions are referred to as a first region, a second region, and a third region from the side closest to the first surface, the average particle size of the particles in the first region is smaller than the average particle size of the particles in the third region.

[0085] (2) In the heat dissipation member of (1) above, in a cross section of the wick, the plurality of voids include a first void having a width larger than the particle diameter of adjacent particles.

[0086] (3) In the heat dissipation member of (1) or (2) above, in a cross section of the wick, the first surface is in communication with the end of the wick on the opposite side to the first surface via the plurality of voids.

[0087] (4) In the heat dissipation member of any one of (1) to (3) above, in the cross section of the wick, the plurality of voids include a second void that is larger in the normal direction than the average particle size of the plurality of particles in the first region and is in contact with the first surface.

[0088] (5) In the heat dissipation member of any one of (1) to (4) above, the particles have a plurality of protrusions and gaps between the plurality of protrusions, and in the cross section of the wick, the width of the void portion connected to the gaps is larger than the width of the gaps.

[0089] (6) The heat dissipation member of (5) above has the hollow portion including an area between two opposing inner surfaces where the wick is not located, and the particles have gaps between multiple protrusions, and the gaps are in contact with the area.

[0090] (7) The heat dissipation member of any one of (1) to (6) above, wherein the base has a second surface exposed to the hollow portion and facing the first surface, the hollow portion has a space between the wick and the second surface, and the space has irregularities in the direction in which the first surface and the second surface face each other.

[0091] (8) A heat dissipation member comprises: a base having a hollow portion and a first surface exposed to the hollow portion; and a wick located in the hollow portion and in contact with the first surface, wherein the wick includes a plurality of voids; and when the region of the hollow portion where the wick is located is divided into three from the first surface to the end on the opposite side of the first surface, and the three regions are called a first region, a second region, and a third region from the side closest to the first surface, the average size of the voids in the first region is smaller than the average size of the voids in the third region.

[0092] In one embodiment, (9) a vapor chamber includes: the heat dissipation member according to any one of (1) to (8) above; and a refrigerant located in the hollow portion.

[0093] In one embodiment, (10) a functional module includes: a heat-generating functional component; and the vapor chamber of (9) above in which the functional component is mounted.

[0094] The present disclosure can be used for heat dissipation members, vapor chambers, and functional modules.

[0095] DESCRIPTION OF SYMBOLS 1 Vapor chamber 10 Heat dissipation member 11 Base 13 Wick 40 Particle 50 Particle 50A First particle 50B Second particle 50C Third particle 50D Fourth particle 51, 51a, 51b Projection 51A First projection 51B Second projection 51C Third projection 53 Virtual central axis 55 Cone-shaped portion 55a Apex portion 60 Particle 61 Projection 111 Hollow portion 111A, 111B Region 111c Space portion 111c1, 111c2 Concave and convex 112 First surface 113 Second surface 115 Support cn Connection portion g, g1, g2, gA, gB Gap G Gap portion G1 First gap portion G2 Second gap portion H Communication path R1 First region R2 Second region R3 Third region T Maximum location wg, wG, wG2 Width w1, w3 Average size φ1, φ3 Average particle size 400A-400E Functional module 410A-410E Functional part

Claims

1. A heat dissipation component comprising: a base having a hollow portion and a first surface exposed in the hollow portion; and a wick located in the hollow portion and in contact with the first surface, wherein the wick has a plurality of particles bonded to one another and a plurality of voids located between the plurality of particles, and when the region in which the wick is located is divided into three from the first surface to the end of the wick opposite to the first surface, and the three regions are referred to as the first region, second region, and third region from the side closest to the first surface, the average particle size of the particles in the first region is smaller than the average particle size of the particles in the third region.

2. The heat dissipation member according to claim 1, wherein in a cross section of the wick, the plurality of voids include first voids having a width greater than the particle diameter of adjacent particles.

3. A heat dissipation member according to claim 1 or claim 2, wherein in a cross section of the wick, the first surface is connected to the end of the wick on the opposite side of the first surface via the plurality of voids.

4. A heat dissipation member as described in any one of claims 1 to 3, wherein in the cross section of the wick, the plurality of voids include second voids that are larger in the normal direction than the average particle size of the plurality of particles in the first region and that are in contact with the first surface.

5. A heat dissipation member according to any one of claims 1 to 4, wherein the particles have a plurality of protrusions and gaps between the plurality of protrusions, and in the cross section of the wick, the width of the void portion connected to the gaps is greater than the width of the gaps.

6. The heat dissipation member according to claim 5, wherein the hollow portion includes an area between two opposing inner surfaces where the wick is not located, and the gap is in contact with the area.

7. A heat dissipation member as described in any one of claims 1 to 6, wherein the base has a second surface exposed to the hollow portion and facing the first surface, the hollow portion has a space between the wick and the second surface, and the space has irregularities in the direction in which the first surface and the second surface face each other.

8. A heat dissipation component comprising: a base having a hollow portion and a first surface exposed in the hollow portion; and a wick located in the hollow portion and in contact with the first surface, wherein the wick includes a plurality of voids; and when the region of the hollow portion where the wick is located is divided into three from the first surface to the end on the opposite side of the first surface, and the three regions are referred to as a first region, a second region, and a third region in order from the side closest to the first surface, the average size of the voids in the first region is smaller than the average size of the voids in the third region.

9. A vapor chamber comprising: a heat dissipation member according to any one of claims 1 to 8; and a refrigerant located in the hollow portion.

10. A functional module comprising: a heat-generating functional component; and the vapor chamber according to claim 9, in which the functional component is mounted.

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